JP5484031B2 - Surface protection film - Google Patents

Description

  The present invention relates to a film for protecting a surface, and more specifically, for protecting a surface of a building member such as a synthetic resin plate, a decorative plate, a metal plate, and a glass plate, and a surface of a constituent member of a liquid crystal display device such as a polarizing plate or a retardation plate. The present invention relates to a propylene-based surface protective film that is suitably used for protection.

Surface protection films are affixed to building materials such as synthetic resin plates, and liquid crystal display parts such as optical equipment and electronic and electrical equipment, from the viewpoint of preventing scratches and dirt on the surface during assembly processing, transportation, etc. It is common to peel off and use the surface protection film after processing or after transportation and transportation.
Conventionally, as the surface protective film, there is a surface protective film mainly composed of an ethylene-based resin. For example, a surface protective film made of an ethylene-based resin that is polymerized from a metallocene catalyst, has a narrow composition distribution and molecular weight distribution, and does not have fish eye is described (for example, see Patent Document 1). Further, a polyethylene composed of 50 to 90% by weight of a specific low density polyethylene and 10 to 50% by weight of a specific high density polyethylene having a weight average molecular weight / number average molecular weight ratio of 9 to 15, and an ethylene-unsaturated ester A laminated film obtained by coextruding an adhesive layer made of a copolymer is described (for example, see Patent Document 2).

However, in the surface protective film described in the above patent document, since polyethylene is the main component, retention occurs inside the molding machine extruder during film formation, gelation occurs due to deterioration of the ethylene component, Since the fish eye is generated, when the product is attached to the object to be protected and stacked and stored as it is, the object to be protected is dented due to the presence of the fish eye. Therefore, for example, even if an attempt is made to use the laminated film as a polarizing plate or a retardation plate used as a liquid crystal display material, there is a problem that the image is distorted due to the dents and cannot be applied.
In addition, in view of the problems of heat resistance, scratch resistance, and rigidity of polyethylene, it is made of polypropylene having a chlorine content of 5 ppm by weight or less, which has improved the point defects of the metal thin film layer due to the influence of chlorine ions. A surface protective film mainly composed of a characteristic propylene-based resin has also been proposed (see, for example, Patent Document 3). However, even in the propylene-based resin described in the patent document, gelation like polyethylene does not occur, but the molecular weight distribution is wide, that is, low molecular weight having a low molecular weight and high molecular weight having a high molecular weight are mixed. Therefore, when the high molecular weight component is formed into a film, an unmelted fine lump becomes a fish eye and exists in the film, resulting in a dent in the protected object.

  Further, both ethylene-based resins and propylene-based resins have a crystallinity distribution, but there is a problem that if the crystallinity distribution is wide and there are many low crystal components, the object to be protected is contaminated. In addition, in the process of producing the polymer, sticking of the low crystal component causes polymer adhesion in a polymerization tank or the like, resulting in deterioration of the polymer due to stagnation, and as a result, fish eyes derived from polymer degradation products exist in the film. As a result, the object to be protected is dented, and there is a problem that it cannot be applied as a surface protective film. In addition, if the crystallinity distribution is wide, the compatibility between the low crystallinity component and the high crystallinity component becomes non-uniform, and the high crystallinity component tends to exist as fish eyes in the form of a fine unmelted mass. Similarly, there is a problem that it cannot be applied as a surface protective film.

JP-A-9-111208 JP 54-133578 A JP 2006-282761 A

  In view of the problems of the prior art described above, the present invention has very little fish eye, excellent blocking properties without using an anti-blocking agent, excellent transparency, and improved peel force control and feeding performance. Further, it is made of a propylene-based resin suitable as a film for protecting a surface of a building member such as a synthetic resin plate, a decorative plate, a metal plate, or a glass plate, and as a surface protecting film for a liquid crystal display component such as a polarizing plate or a retardation plate. It aims at providing the film for surface protection.

  As a result of repeating various studies in order to solve the above problems, the present inventor used a propylene-ethylene block copolymer having a specific MFR produced by a specific manufacturing method as a base material layer, a specific MFR, density, The ratio of the weight average molecular weight to the number average molecular weight determined by gel permeation chromatography, a soft polypropylene resin having a soluble content of −15 ° C. or less measured by a temperature rising elution fractionation method, is used for the adhesive layer. Made of a propylene resin with excellent transparency, with less fisheye, better flexibility, improved peel force control and feeding performance The inventors found that a self-adhesive film for surface protection was obtained, and completed the present invention.

That is, according to the first aspect of the present invention, in the surface protective film in which the adhesive layer is formed on one surface of the base material layer and the release treatment layer is formed on the other surface, the base material layer is a metallocene catalyst. And the following (a1) to (a3), (a5), (a8) and (a9) are used to form the propylene-ethylene block copolymer (A), and the adhesive layer has the following (b1) A film for surface protection formed of a soft polypropylene resin (B) having the characteristics of (b4), wherein the release treatment layer is formed of a silicone-based or long-chain alkyl release agent (C) Is provided.
(A) Propylene-ethylene block copolymer (a1) 30-95 propylene-ethylene random copolymer component (A1) having an ethylene content of 0.5-6 wt% in the first step using a metallocene catalyst. Propylene-ethylene obtained by sequential polymerization of 70 to 5 wt% of propylene-ethylene random copolymer component (A2) containing 6 to 20 wt% more ethylene than component (A1) in the second step. Block copolymer (a2) Melt flow rate (MFR: 230 ° C. 2.16 kg) is 1 to 30 g / 10 min
(A3) The component amount W having a molecular weight of 5,000 or less obtained by gel permeation chromatography (GPC) is 0.8% by weight or less of the whole.
(A5) TREF elution curve obtained as a plot of elution amount (dWt% / dT) against temperature by the temperature rising elution fractionation method (TREF) in the temperature range of −15 ° C. to + 140 ° C. using an o-dichlorobenzene solvent In
The peak temperature T (A1) observed on the high temperature side is in the range of 55 ° C. to 96 ° C.,
The peak temperature T (A2) observed on the low temperature side is 45 ° C. or lower, or the peak temperature T (A2) is not observed,
The temperature T (A4) at which 99% by weight of the propylene-ethylene block copolymer elutes is 98 ° C. or lower.
(A8) Intrinsic viscosity [η] cxs measured in a 135 ° C. decalin for 23 ° C. xylene solubles is 1 to 2 dl / g
(A9) In the temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA), the tan δ curve has a single peak at 0 ° C. or less. (B) Soft propylene resin (b1) Melt flow rate ( MFR: 230 ° C., 2.16 kg) is 2 to 30 g / 10 minutes (b2) Density is 0.85 to 0.89 g / cm ³
(B3) The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 1.5-3.
(B4) Soluble content (S- ₁₅ ) of -15 [deg.] C. or lower measured by temperature rising elution fractionation (TREF) method is 55% by weight or more

According to a second aspect of the present invention, there is provided a surface protective film characterized in that, in the first aspect, the propylene-ethylene block copolymer (A) satisfies the following property (a4): Is done.
(A4) In the component (A1) obtained in the first step, the proportion of the entire propylene-ethylene block copolymer is in the range of 30 to 85% by weight,
In the component (A2) obtained in the second step, the proportion of the entire propylene-ethylene block copolymer is in the range of 70 to 15% by weight.

According to the third invention of the present invention, in the first or second invention, the propylene-ethylene block copolymer (A) satisfies the following characteristics (a6) to (a7): A surface protecting film is provided.
(A6) The component (A1) obtained in the first step is a propylene-ethylene random copolymer having an ethylene content of 1.5 to 6% by weight, and the proportion of the propylene-ethylene block copolymer is 30 to 70% by weight. % Range,
The component (A2) obtained in the second step has an ethylene content that is 8 to 15% by weight higher than that of the component (A1), and the proportion of the entire propylene-ethylene block copolymer is in the range of 70 to 30% by weight. (A7) TREF elution curve obtained as a plot of elution amount (dWt% / dT) against temperature by the temperature rising elution fractionation method (TREF) in the temperature range of −15 ° C. to + 140 ° C. using an o-dichlorobenzene solvent In
The peak temperature T (A1) observed on the high temperature side is in the range of 60 ° C. to 88 ° C.,
The peak temperature T (A2) observed on the low temperature side is 40 ° C. or lower, or the peak temperature T (A2) is not observed,
The temperature T (A4) at which 99% by weight of the propylene-ethylene block copolymer elutes is 90 ° C. or lower.

According to a fourth aspect of the present invention, there is provided a surface protecting film that is used for protecting the surface of a building member in any one of the first to third aspects.
Furthermore, according to a fifth aspect of the present invention, there is provided a surface protective film characterized in that in any one of the first to third aspects, the surface protective film is used for protecting a surface of a constituent member of a liquid crystal display device. .

The film for surface protection of the present invention uses a specific propylene-ethylene block copolymer polymerized by using a metallocene catalyst for the base material layer, and uses a specific soft polypropylene resin for the adhesive layer. When at least one of the adhesive layer and the adhesive layer are laminated in a molten state, it adheres firmly and has excellent delamination, so that there is very little unmelted fish eye during film formation, and delamination between the adhesive layer and the substrate layer There is no fear of it, it is rich in flexibility, and it exhibits excellent adhesiveness. For this reason, even if a surface protection film is affixed on a to-be-protected object and stored in a stacked manner, the to-be-protected object does not dent.
Moreover, the film for surface protection of this invention is excellent in blocking property without using an antiblocking agent, and is excellent in transparency. Furthermore, since a silicone-based or long-chain alkyl-based release treatment agent is used for the release treatment layer as the release treatment layer, when the roll is unwound from the roll winding state where both the adhesive layer and the release treatment layer are in contact with each other in a solid state, It can be made into a film for surface protection having the property that peeling and improving the drawability during use.

It is a figure which shows the elution amount and elution amount integration | accumulation of the components (A1) and (A2) by TREF.

The present invention relates to a propylene-based surface protective film having an adhesive layer formed on one surface of a base material layer and having a release treatment layer on the opposite surface of the adhesive layer, and the base material layer is polymerized using a metallocene catalyst. And the characteristics (a1) and (a2), and if necessary, the propylene-ethylene block copolymer (A) further having the characteristics (a3) to (a9), and the adhesive layer having the characteristics (b1) to A film for surface protection, characterized in that it is formed of a soft polypropylene resin (B) having (b4), and the release treatment layer is formed of a silicone-based or long-chain alkyl release agent (C).
Hereinafter, the component of each layer of the film for surface protection of this invention and the manufacturing method of the film for surface protection are demonstrated in detail.

1. Base material layer The following propylene-ethylene block copolymer (A) is used for the base material layer and the adhesion layer in the film for surface protection of this invention.

  The propylene-ethylene block copolymer (A) used in the present invention is a propylene homopolymer or a propylene-ethylene random copolymer component (A1) (hereinafter sometimes referred to as component (A1)) and propylene-. It is composed of an ethylene random copolymer component (A2) (hereinafter also referred to as component (A2)), and the following properties (a1) to (a2), and further, if necessary, properties (a3) to (a9) It satisfies.

(A1) 30 to 95% by weight of propylene homopolymer or propylene-ethylene random copolymer component (A1) in the first step and more ethylene than component (A1) in the second step using the metallocene catalyst Propylene-ethylene block copolymer (A) obtained by sequentially polymerizing 70 to 5% by weight of a propylene-ethylene random copolymer component (A2) containing Although it is commonly called a block copolymer, it is in a blended state of the component (A1) and the component (A2), and both are not bonded by polymerization.
(A2) Melt flow rate (MFR: 230 ° C. 2.16 kg) is 1 to 30 g / 10 min

(A3) The component amount W (Mw ≦ 5,000) having a molecular weight of 5,000 or less obtained by gel permeation chromatography (GPC) measurement is 0.8% by weight or less of the total (a4) obtained in the first step. Component (A1) is a propylene-ethylene random copolymer having an ethylene content of 0.5 to 6% by weight, and the proportion of the total propylene-ethylene block copolymer is in the range of 30 to 85% by weight. The component (A2) obtained in (6) has an ethylene content of 6 to 20% by weight more than (A1), and the proportion in the entire propylene-ethylene block copolymer is in the range of 70 to 15% by weight (a5). Elution amount (dWt% / dT) with respect to temperature by temperature rising elution fractionation method (TREF) in a temperature range of −15 ° C. to + 140 ° C. using o-dichlorobenzene solvent In TREF elution curve obtained as a lot,
The peak temperature T (A1) observed on the high temperature side is in the range of 55 ° C. to 96 ° C.,
The peak temperature T (A2) observed on the low temperature side is 45 ° C. or lower, or the peak temperature T (A2) is not observed,
The temperature T (A4) at which 99% by weight of the propylene-ethylene block copolymer elutes is 98 ° C. or lower.

(A6) The component (A1) obtained in the first step is a propylene-ethylene random copolymer having an ethylene content in the range of 1.5 to 6% by weight, and the proportion of the entire block copolymer is 30 to 70. The component (A2) in the range of wt% and obtained in the second step has an ethylene content of 8 to 15 wt% more than (A1), and the proportion in the total propylene-ethylene block copolymer is 70 to In the range of 30% by weight

(A7) TREF elution curve obtained as a plot of elution amount (dWt% / dT) against temperature by the temperature rising elution fractionation method (TREF) in the temperature range of −15 ° C. to 140 ° C. using an o-dichlorobenzene solvent In
The peak temperature T (A1) observed on the high temperature side is in the range of 60 ° C. to 88 ° C.,
The peak temperature T (A2) observed on the low temperature side is 40 ° C. or lower, or the peak temperature T (A2) is not observed,
The temperature T (A4) at which 99% by weight of the propylene-ethylene block copolymer elutes is 90 ° C. or lower. (A9) In the temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA), the tan δ curve has a single peak at 0 ° C. or lower. Characteristic (a1) -(A9) is demonstrated in detail.

(1) Ethylene content in component (A1) ([E] _A1 )
The component (A1) produced in the first step suppresses stickiness of the film and exhibits heat resistance, so that the propylene homopolymer or propylene-ethylene random copolymer having a relatively high melting point and crystallinity. Must be coalesced. Ethylene content of component _{(A1) ([E] A1} ) is preferably at 7 wt% or less, more preferably 6 wt% or less, more preferably from 0.5 to 6 wt. [E] When _A1 exceeds 7% by weight, the melting point becomes too low and the heat resistance of the film may be deteriorated.
In addition, although component (A1) shows the adhesiveness and heat resistance which were improved also with the propylene homopolymer, in order to exhibit sufficient adhesiveness when component (A1) is a propylene homopolymer, the component (described later) There is a need to extremely increase the ratio of A2), which may cause deterioration of heat resistance, stickiness, blocking, and the like.
On the other hand, when component (A1) is a propylene-ethylene random copolymer, although the melting point of component (A1) itself decreases, the heat resistance seems to deteriorate, but it is necessary to exhibit sufficient adhesiveness. Since the amount of the component (A2) can be suppressed, the heat resistance of the block copolymer as a whole is rather improved, and stickiness and blocking are less deteriorated, which is preferable.
Further, by reducing the melting point, it is possible to obtain a film excellent in odor and the like because sufficient extrusion stability and the like can be obtained even if the molding temperature during film molding is lowered.
From these viewpoints, the ethylene content [E] _A1 in the component (A1) is preferably 0.5% by weight or more, more preferably 1.5% by weight or more.

(2) Ethylene content in component (A2) ([E] _A2 )
The propylene-ethylene random copolymer component (A2) produced in the second step is a component necessary for improving the tackiness, impact resistance and flexibility of the propylene-ethylene block copolymer (A). .
Here, the component (A2) needs to have an ethylene content in a specific range in order to sufficiently exhibit the above effects. That is, in the block copolymer of the present invention, the lower the crystallinity of the component (A2) relative to the component (A1), the greater the effect of improving the tackiness, and the crystallinity is the ethylene content in the propylene-ethylene random copolymer. Therefore, the ethylene content [E] _A2 in the component (A2) needs to be larger than the ethylene content [E] _A1 E in the component (A1), and preferably 3% by weight or more. Preferably it is 6 weight% or more, More preferably, it is 8 weight% or more, and contains more ethylene than a component (A1).
Here, when the difference in ethylene content between the component (A1) and the component (A2) is defined as [E] gap ([E] _A2− [E] _A1 ), [E] gap is in the range of 3 to 20% by weight. More preferably, it is 6 to 20 weight%, More preferably, it is 8 to 15 weight%.
[E] If the gap is less than 3% by weight, the rubber elasticity is insufficient, which is not preferable. On the other hand, if it exceeds 20% by weight, a phase separation structure divided into a matrix and a domain of the component (A1) and the component (A2) produced in the first step is taken and compatibility is deteriorated, so that fish eyes may be generated. There is. This is because polypropylene originally has low compatibility with polyethylene, and even in the case of propylene-ethylene random copolymers, although the ethylene content is different, the compatibility with each other decreases as the difference in ethylene content increases. is there.

(3) Ratio of component (A1) and component (A2) Ratio of component (A1) constituting propylene-ethylene block copolymer (W (A1)) and ratio of component (A2) (W (A2)) The content ratio should be such that W (A1) is 30 to 95% by weight and W (A2) is in the range of 70 to 5% by weight, and preferably the ratio of W (A1) is 30 to 85% by weight. %, More preferably in the range of 30 to 70% by weight.
If the ratio of W (A1) is less than 30% by weight, stickiness of the film may occur and heat resistance may be reduced. On the other hand, when the proportion of W (A1) exceeds 95% by weight, the effect of improving the tackiness and impact resistance of the propylene-ethylene block copolymer cannot be sufficiently exhibited.
When the proportion of the component (A2) is too large, the stickiness increases, the blocking is deteriorated, and the heat resistance is significantly reduced. On the other hand, if the proportion of the component (A2) is too small, the effect of improving the adhesiveness and impact resistance cannot be obtained.

(4) Measurement of _{[E] A1} and _{[E] A2} and W (A1) and was measured above W (A2) _{[E] A1} and _{[E] A2} and W (A1) and W (A2) is prepared Although it is possible to specify by the material balance of the time (material balance), in order to specify these more accurately, it is desirable to use the following analysis.
(I) Identification of W (A1) and W (A2) by temperature-temperature elution fractionation (TREF) The technique for evaluating the crystallinity distribution of a propylene-ethylene random copolymer by TREF is well known to those skilled in the art. Yes, for example, detailed measurement methods are shown in the following documents.
G. Glockner, J. et al. Appl. Polym. Sci. : Appl. Polym. Symp. 45, 1-24 (1990)
L. Wild, Adv. Polym. Sci. 98, 1-47 (1990)
J. et al. B. P. Soares, A .; E. Hamielec, Polymer; 36,
8, 1639-1654 (1995)

  The propylene-ethylene block copolymer in the present invention is greatly different in the crystallinity of each of the components (A1) and (A2), and each crystallinity distribution is narrow by being produced using a metallocene catalyst. Therefore, there are very few intermediate components between the two, and both can be discriminated with high accuracy by TREF.

A specific method will be described with reference to the figure showing the elution amount and the elution amount integration by TREF in FIG.
FIG. 1 is a graph of a TREF elution curve of a propylene-ethylene block copolymer (PEB-1) for a base material layer of the present invention produced in Example (Production Example 1). The plot line in the upper diagram of FIG. 1 shows the elution amount at each temperature, and the plot line in the lower diagram shows the integration of the elution amount.
In the TREF elution curve (plot of elution amount versus temperature), components (A1) and (A2) show their elution peaks at T (A1) and T (A2), respectively, due to the difference in crystallinity. Since it is large, separation is possible at an intermediate temperature T (C) (= {T (A1) + T (A2)} / 2).
In addition, the lower limit of the TREF measurement temperature is −15 ° C. in the apparatus used for this measurement, but in the case where the crystallinity of the component (A2) is very low or an amorphous component, There may be no peak in the range. (In this case, the concentration of the component (A2) dissolved in the solvent is detected at the measurement temperature lower limit (ie, −15 ° C.).)
At this time, T (A2) is considered to exist below the lower limit of the measurement temperature, but the value cannot be measured. In such a case, T (A2) is the lower limit of the measurement temperature. Defined as ° C.
Here, if the integrated amount of the component eluting up to T (C) is defined as W (A2) wt%, and the integrated amount of the portion eluting at T (C) or higher is defined as W (A1) wt%, W (A2) Almost corresponds to the amount of the component (A2) having low crystallinity or non-crystallinity, and the integrated amount W (A1) of the component eluted at T (C) or higher is the component (A1) having relatively high crystallinity. Almost corresponds to the amount of. The elution amount curve obtained by TREF and the above-described methods for calculating the various temperatures and amounts obtained therefrom are performed as illustrated in FIG.

(Ii) Method for measuring TREF In the present invention, TREF is specifically measured as follows.
A sample is dissolved in o-dichlorobenzene (containing 0.5 mg / mL BHT) at 140 ° C. to prepare a solution. This is introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, subsequently cooled to −15 ° C. at a rate of 4 ° C./min, and held for 60 minutes. Thereafter, o-dichlorobenzene (containing 0.5 mg / mL BHT) as a solvent is flowed through the column at a flow rate of 1 mL / min, and components dissolved in o-dichlorobenzene at −15 ° C. are eluted in the TREF column for 10 minutes. Next, the column is linearly heated to 140 ° C. at a heating rate of 100 ° C./hour to obtain an elution curve.

(Iii) Specificity of ethylene content [E] _A1 and [E] _A2 in each component (a) Separation of component (A1) and component (A2) Based on T (C) determined by the above TREF measurement, Using a temperature-separating column separation method using a preparative type separation apparatus, the soluble component (A2) in T (C) and the insoluble component (A1) in T (C) are separated, and the ethylene content of each component is determined by NMR. .
The temperature rising column fractionation method refers to a measurement method disclosed in, for example, Macromolecules, 21 314 to 319 (1988). Specifically, the following method is used in the present invention.
(B) Fractionation conditions A cylindrical column having a diameter of 50 mm and a height of 500 mm is filled with a glass bead carrier (80 to 100 mesh) and maintained at 140 ° C. Next, 200 mL of the o-dichlorobenzene solution (10 mg / mL) of the sample dissolved at 140 ° C. is introduced into the column. Thereafter, the temperature of the column is cooled to 0 ° C. at a rate of temperature decrease of 10 ° C./hour. After holding at 0 ° C. for 1 hour, the column temperature is heated to T (C) at a heating rate of 10 ° C./hour and held for 1 hour. Note that the temperature control accuracy of the column through a series of operations is ± 1 ° C.
Next, while maintaining the column temperature at T (C), 800 mL of o (dichlorobenzene) of T (C) is allowed to flow at a flow rate of 20 mL / min, whereby components soluble in T (C) existing in the column are obtained. Elute and collect.
Next, the column temperature is increased to 140 ° C. at a temperature rising rate of 10 ° C./min, and after leaving still at 140 ° C. for 1 hour, by flowing 800 mL of a 140 ° C. solvent (o-dichlorobenzene) at a flow rate of 20 mL / min, Elute insoluble components with T (C) and collect.
The solution containing the polymer obtained by fractionation is concentrated to 20 mL using an evaporator and then precipitated in 5 times the amount of methanol. The precipitated polymer is recovered by filtration and then dried overnight in a vacuum dryer.

^(C) 13 C-NMR according to the measurement the fractionated by components obtained ethylene content ^{(A1) (A2) 13 C} -NMR spectrum ethylene content was determined according to the following conditions by complete proton decoupling method for each It is obtained by analyzing.
Model: GSX-400 manufactured by JEOL Ltd. or equivalent equipment (carbon nuclear resonance frequency of 100 MHz or more)
Solvent: o-dichlorobenzene / heavy benzene = 4/1 (volume ratio)
Concentration: 100 mg / mL
Temperature: 130 ° C
Pulse angle: 90 °
Pulse interval: 15 seconds Integration count: 5,000 times or more The attribution of the spectrum may be performed with reference to, for example, Macromolecules, 17 1950 (1984).
The spectrum assignments measured under the above conditions are as shown in Table 1 below. In Table 1, symbols such as S _αα represent Carman et al. (Macromolecules, 10536 (1977)), P represents methyl carbon, S represents methylene carbon, and T represents methine carbon.

Hereinafter, when “P” is a propylene unit in a copolymer chain and “E” is an ethylene unit, six kinds of triads of PPP, PPE, EPE, PEP, PEE, and EEE may exist in the chain. As described in Macromolecules, 15 1150 (1982), the concentration of these triads and the peak intensity of the spectrum are linked by the following relational expressions (1) to (6).
[PPP] = k × I (T _ββ ) (1)
[PPE] = k × I (T _βδ ) (2)
[EPE] = k × I (T _δδ ) (3)
[PEP] = k × I (S _ββ ) (4)
[PEE] = k × I (S _βδ ) (5)
[EEE] = k × {I (S _δδ ) / 2 + I (S _γδ ) / 4} (6)
Here, [] indicates the fraction of triads, for example, [PPP] is the fraction of PPP triads in all triads. Therefore,
[PPP] + [PPE] + [EPE] + [PEP] + [PEE] + [EEE] = 1 (7)
It is.
Further, k is a constant, I indicates the spectral intensity, and for example, I (T _ββ ) means the intensity of the peak at 28.7 ppm attributed to T _ββ .

By using the relational expressions of the above formulas (1) to (7), the fraction of each triad is obtained, and the ethylene content is obtained by the following formula.
Ethylene content (mol%) = ([PEP] + [PEE] + [EEE]) × 100

  The propylene-ethylene random copolymer of the present invention contains a small amount of a propylene hetero bond (2,1-bond and / or 1,3-bond), thereby producing the following minute peak.

In order to obtain an accurate ethylene content, it is necessary to include these peaks derived from heterogeneous bonds in the calculation. Therefore, the ethylene content of the present invention is obtained by using the relational expressions (1) to (7) in the same manner as the analysis of the copolymer produced with a Ziegler catalyst that does not substantially contain a heterogeneous bond. To do.
Conversion from mol% to wt% of ethylene content is carried out using the following formula: ethylene content (wt%) = (28 × X / 100) / {28 × X / 100 + 42 × (1−X / 100) } × 100
Here, X is the ethylene content in mol%.

The ethylene content [E] _W of the entire propylene-ethylene block copolymer is calculated from the respective ethylene contents [E] _A1 , [E] _A2 and TREF measured from the components (A1) and (A2). From the weight ratios W (A1) and W (A2)% by weight of the respective components, the following formula is used.
[E] _W = {[E] _A1 × W (A1) + [E] _A2 × W (A2) / 100 (% by weight)

(4) Melt flow rate (MFR) of propylene-ethylene block copolymer (A)
The melt flow rate (MFR) of the propylene-ethylene block copolymer used in the present invention is 1 to 30 g / 10 minutes, preferably 4 to 15 g / 10 minutes. When the MFR is less than 1 g / 10 min, surface roughness called shark skin or melt fracture occurs on the surface of the film and the appearance is remarkably impaired. On the other hand, if the MFR is too high, the stability during molding deteriorates, the width and thickness of the film vary, and a product cannot be obtained.
Here, MFR is a value measured at a heating temperature of 230 ° C. and a load of 2.16 kg (21.18 N) in accordance with JIS K7210 A method condition M.

(5) Definition by peak of tan δ curve In the present invention, in order to maintain good compatibility of the film, the component (A1) and the component (A2) constituting the propylene-ethylene block copolymer to be used are phase separated. It is necessary not to do. The phase separation conditions are affected not only by the ethylene content but also by the molecular weight and composition. Therefore, in addition to the above-mentioned regulations regarding the ethylene content, a temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA) Therefore, it is necessary to define the peak of the tan δ curve.
In the propylene-ethylene block copolymer (A) used in the present invention, in the temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA), the tan δ curve has a single peak at 0 ° C. or lower. It is preferable to have.
When the propylene-ethylene block copolymer (A) has a phase separation structure, the glass transition temperature of the amorphous part contained in the component (A1) and the glass transition temperature of the amorphous part contained in the component (A2) are Since each is different, there are a plurality of peaks. In this case, there arises a problem that fish eyes are likely to occur.
Whether or not the phase separation structure is taken can be determined in the tan δ curve in the solid viscoelasticity measurement, and the tan δ curve has a single peak below 0 ° C. Is brought about by

  Specifically, solid viscoelasticity measurement is performed by applying a sinusoidal strain of a specific frequency to a strip-shaped sample piece and detecting the generated stress. Here, the frequency is 1 Hz and the measurement temperature is raised stepwise from −60 ° C. until the sample is melted and cannot be measured. Further, it is recommended that the magnitude of distortion is about 0.1 to 0.5%. From the obtained stress, the storage elastic modulus G ′ and the loss elastic modulus G ″ are obtained by a known method, and the loss tangent (= loss elastic modulus / storage elastic modulus) defined by this ratio is plotted against the temperature. It shows a sharp peak in the temperature range below 0 ° C. Generally, the peak of the tan δ curve below 0 ° C. is for observing the glass transition of the amorphous part, and here the peak temperature is defined as the glass transition temperature Tg (° C.). Define.

(6) Molecular weight The amount of the component having a weight average molecular weight of 5,000 or less as measured by the gel permeation (GPC) method of the propylene-ethylene block copolymer used in the present invention is preferably 0.8% by weight or less. More preferably, it is 0.5 wt% or less. The propylene-ethylene block copolymer (A) in the present invention has an additional feature that the low molecular weight component is small, and the low molecular weight component, particularly the component whose molecular weight is less than the entangled molecular weight, It seems to bleed out on the surface and deteriorate stickiness and transparency.
In addition, the molecular weight between the entanglement points of polypropylene is about 5,000 as described in Journal of Polymer Science: Part B: Polymer Physics; 37 1023-1103 (1999).

Here, the weight average molecular weight (Mw) refers to that measured by gel permeation chromatography (GPC).
Conversion from the retention volume to the molecular weight is performed using a calibration curve prepared in advance with standard polystyrene.
Standard polystyrenes used are the following brands manufactured by Tosoh Corporation. F380, F288, F128, F80, F40, F20, F10, F4, F1, A5000, A2500, A1000
A calibration curve is prepared by injecting 0.2 ml of a solution dissolved in o-dichlorobenzene (containing 0.5 mg / ml BHT) so that each is 0.5 mg / ml.
The calibration curve uses a cubic equation obtained by approximation by the least square method. Viscosity formula used for conversion to molecular weight: [η] = K × M ^α uses the following numerical values.
PS: K = 1.38 × 10 ⁻⁴ α = 0.7
PE: K = 3.92 × 10 ⁻⁴ α = 0.733
PP: K = 1.03 × 10 ⁻⁴ α = 0.78

The measurement conditions for GPC are as follows.
Apparatus: GPC (ALC / GPC 150C) manufactured by WATERS
Detector: MIRAN 1A IR detector manufactured by FOXBORO (measurement wavelength: 3.42 μm)
Column: AD806M / S (3 pieces) manufactured by Showa Denko KK
Mobile phase solvent: o-dichlorobenzene Measurement temperature: 140 ° C.
Flow rate: 1.0 ml / min
Injection volume: 0.2ml
Sample Preparation Prepare a 1 mg / ml solution using o-dichlorobenzene (containing 0.5 mg / ml BHT) and dissolve it at 140 ° C. for about 1 hour.
The amount of the component having a molecular weight of 5,000 or less can also be determined from a plot of the elution ratio with respect to the molecular weight obtained by GPC measurement.

(7) Intrinsic viscosity [η] cxs
In the propylene-ethylene block copolymer (A), stickiness and bleed-out are particularly problematic because it is a component soluble in xylene at normal temperature (CXS component). It is preferable to carry out for the CXS component.
Here, the CXS component was prepared by dissolving the propylene-ethylene block copolymer (A) in p-xylene at 130 ° C. to form a solution, and then leaving the solution at 25 ° C. for 12 hours. The intrinsic viscosity [η] cxs of the CXS component obtained by evaporating p-xylene can be measured using a Ubbelohde viscometer at a temperature of 135 ° C. using decalin as a solvent.
At this time, since the propylene-ethylene block copolymer (A) of the present invention does not increase the generation of a component having a molecular weight of 5,000 or less that tends to bleed out, the conventional Ziegler-Natta catalyst is Even if the intrinsic viscosity [η] cxs of the CXS component is in the region of 2 or less, which has been a practical problem due to deterioration of the above problems or blocking, it can be produced and used without causing any particular deterioration of physical properties. it can.
The propylene-ethylene block copolymer which does not increase the component having a molecular weight of 5,000 or less while lowering the intrinsic viscosity of such a CXS component has characteristics in terms of physical properties such as high tensile elongation at break and high tensile strength at break. In addition, there is an effect that there is little occurrence of an appearance defect called “butsu” or “fish eye”.

(8) Additional requirements for crystallinity distribution by TREF elution curve By using the TREF elution curve used to specify the amount of each component, it was added to the propylene-ethylene block copolymer of the present invention in the crystallinity distribution. Characteristic can be found.
(I) Elution peak temperature T (A1)
The higher the elution peak temperature T (A1) of the component (A1) in the TREF elution curve, the higher the crystallinity of the component (A1). At this time, the higher the crystallinity of the component (A1), the higher the propylene-ethylene block content. The component (A2) necessary for improving the adhesiveness of the polymer (A) must be increased.
On the other hand, if the proportion of the component (A2) is too large, stickiness and heat resistance are deteriorated. Therefore, in order to improve the balance between adhesiveness and flexibility, T (A1) should not be too high. Further, odor properties and the like tend to deteriorate with an increase in molding temperature, but it is also preferable in that stable plasticization can be obtained by reducing T (A1) even if the extrusion temperature is lowered.
In the present invention, the component (A1) is a propylene homopolymer or a propylene / ethylene random copolymer, but T (A1) can be decreased by increasing the ethylene content. At this time, in order to exhibit a sufficient balance of adhesiveness, flexibility and heat resistance, T (A1) is preferably 96 ° C. or lower, and the most preferable range is preferably 88 ° C. or lower.
On the other hand, when the elution peak temperature T (A1) is less than 55 ° C., the temperature at which the component (A1) crystals melt is low, and the propylene-ethylene block copolymer can exhibit sufficient heat resistance. In the present invention, the peak temperature T (A1) is preferably 55 ° C. or higher, and more preferably 60 ° C. or higher.

(Ii) Elution end temperature T (A4)
Even if the peak temperature T (A1) is low, the fisheye is deteriorated if the crystallinity distribution is present on the high crystal side. The cause of this is not clear, but if there is a crystalline distribution on the high crystal side, the density of the crystal structure increases and the density difference from the amorphous part increases, or the nucleation frequency decreases and the spherulite size increases. This is probably because of this.
Therefore, it is preferable that the crystallinity spread to the high temperature side is suppressed in the TREF elution curve. The spread of crystallinity toward the high crystal side can be evaluated by TREF measurement, and the elution end temperature T (A4) of the entire component propylene-ethylene block copolymer (A) with respect to the peak temperature T (A1) (however, Considering errors in TREF measurement, it is difficult to define the temperature at which all elution occurs, so in the present invention, the temperature at which 99% by weight of the total elution is defined as the elution end temperature T (A4)) should not be high. Preferably, if there is an elution component on the high temperature side, the crystallinity of the component increases. Therefore, as a preferable requirement of the present invention, T (A4) is 98 ° C. or less, preferably 90 ° C. or less.
Furthermore, the temperature difference ΔT (T (A4) −T (A1)) from the elution peak to the end of elution is preferably 5 ° C. or less, more preferably 4 ° C. or less, and even more preferably 3 ° C. or less.

(Iii) Elution peak temperature T (A2)
Since the adhesiveness and flexibility of the propylene-ethylene block copolymer (A) cannot be ensured unless the crystallinity of the component (A2) is sufficiently lowered, T (A2) is preferably 45 ° C. or less. More preferably, it is 40 degrees C or less.

(9) Production of propylene-ethylene block copolymer (A) The method for producing the propylene-ethylene block copolymer (A) of the present invention requires the use of a metallocene catalyst. It is well known to those skilled in the art that stickiness and bleedout deteriorate when the molecular weight and crystallinity distribution are wide in the propylene-ethylene block copolymer, but also in the propylene-ethylene block copolymer used in the present invention, In order to suppress stickiness and bleed-out, and to achieve less fisheye in film forming, it is necessary to polymerize using a metallocene catalyst that can narrow the molecular weight and crystallinity distribution. The fact that the propylene-ethylene block copolymer of the present invention cannot be obtained with a Natta-based catalyst is also apparent from the comparison of Examples and Comparative Examples described later.

Here, the type of the metallocene-based catalyst is not particularly limited as long as a copolymer having the performance of the present invention can be produced, but in order to satisfy the requirements of the present invention, for example, as shown below: It is preferable to use a metallocene-based catalyst comprising the component (x), the component (y), and the component (z) used as necessary.
Component (x): At least one metallocene transition metal compound selected from transition metal compounds represented by the following general formula (1) Component (y): At least selected from the following (y-1) to (y-4) One kind of solid component (y-1) An ionic compound capable of reacting with a particulate carrier (y-2) on which an organoaluminoxy compound is supported and converting the component (x) into a cation by reacting with the component (x) Or a particulate carrier carrying a Lewis acid (y-3) a solid acid particulate (y-4) an ion-exchange layered silicate component (z): an organoaluminum compound

Ingredient (x)
As the component (x), at least one metallocene transition metal compound selected from transition metal compounds represented by the following general formula (1) can be used.
^{_{Q (C 5 H 4-a}} -aR 1) (C 5 H 4-b -bR 2) MeXY ... (1)
[Wherein Q represents a divalent linking group that bridges two conjugated five-membered ring ligands, Me represents a metal atom selected from titanium, zirconium, and hafnium, and X and Y represent hydrogen atoms. Atom, halogen atom, hydrocarbon group, alkoxy group, amino group, nitrogen-containing hydrocarbon group, phosphorus-containing hydrocarbon group or silicon-containing hydrocarbon group, X and Y are each independently, ie, the same or different. Also good. R ¹ and R ² represent hydrogen, a hydrocarbon group, a halogenated hydrocarbon group, a silicon-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, an oxygen-containing hydrocarbon group, a boron-containing hydrocarbon group, or a phosphorus-containing hydrocarbon group. . a and b are the number of substituents. ]

Specifically, Q represents a divalent linking group that bridges two conjugated five-membered ring ligands. For example, a divalent hydrocarbon group, a silylene group, an oligosilylene group, or a hydrocarbon group as a substituent. Examples thereof include a silylene group, an oligosilylene group, or a germylene group having a hydrocarbon group as a substituent. Among these, preferred is a silylene group having a divalent hydrocarbon group and a hydrocarbon group as a substituent.
X and Y represent a hydrogen atom, a halogen atom, a hydrocarbon group, an alkoxy group, an amino group, a nitrogen-containing hydrocarbon group, a phosphorus-containing hydrocarbon group, or a silicon-containing hydrocarbon group. Among these, hydrogen is preferable , Chlorine, methyl, isobutyl, phenyl, dimethylamide, diethylamide group and the like. X and Y may be independent, that is, may be the same or different.

R ¹ and R ² represent hydrogen, a hydrocarbon group, a halogenated hydrocarbon group, a silicon-containing hydrocarbon group, a nitrogen-containing hydrocarbon group, an oxygen-containing hydrocarbon group, a boron-containing hydrocarbon group, or a phosphorus-containing hydrocarbon group. .
Specific examples of the hydrocarbon group include a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, an octyl group, a phenyl group, a naphthyl group, a butenyl group, and a butadienyl group. In addition, halogenated hydrocarbon group, silicon-containing hydrocarbon group, nitrogen-containing hydrocarbon group, oxygen-containing hydrocarbon group, boron-containing hydrocarbon group or phosphorus-containing hydrocarbon group include methoxy group, ethoxy group, phenoxy group, trimethylsilyl group. Typical examples include a group, a diethylamino group, a diphenylamino group, a pyrazolyl group, an indolyl group, a dimethylphosphino group, a diphenylphosphino group, a diphenylboron group, and a dimethoxyboron group. Among these, a hydrocarbon group having 1 to 20 carbon atoms is preferable, and a methyl group, an ethyl group, a propyl group, and a butyl group are particularly preferable.
By the way, adjacent R ¹ and R ² may combine to form a ring, on which a hydrocarbon group, halogenated hydrocarbon group, silicon-containing hydrocarbon group, nitrogen-containing hydrocarbon group, oxygen-containing You may have a substituent which consists of a hydrocarbon group, a boron containing hydrocarbon group, or a phosphorus containing hydrocarbon group.
Me is a metal atom selected from titanium, zirconium and hafnium, preferably zirconium and hafnium.

  Among the components (x) described above, preferred for production of the propylene-ethylene block copolymer of the present invention is a substituted cyclopenta crosslinked with a silylene group, a germylene group or an alkylene group having a hydrocarbon substituent. It is a transition metal compound composed of a ligand having a dienyl group, a substituted indenyl group, a substituted fluorenyl group, or a substituted azulenyl group, and particularly preferably a 2, 2 crosslinked by a silylene group having a hydrocarbon substituent or a germylene group. It is a transition metal compound comprising a ligand having a 4-position substituted indenyl group and a 2,4-position substituted azulenyl group.

Non-limiting examples include
Dimethylsilylene bis (2-methyl-4-phenylindenyl) zirconium dichloride,
Diphenylsilylenebis (2-methyl-4-phenylindenyl) zirconium dichloride,
Dimethylsilylenebis (2-methylbenzoindenyl) zirconium dichloride,
Dimethylsilylenebis {2-isopropyl-4- (3,5-diisopropylphenyl) indenyl} zirconium dichloride,
Dimethylsilylene bis (2-propyl-4-phenanthrylindenyl) zirconium dichloride,
Dimethylsilylenebis (2-methyl-4-phenylazurenyl) zirconium dichloride,
Dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) azurenyl} zirconium dichloride,
Dimethylsilylenebis (2-ethyl-4-phenylazurenyl) zirconium dichloride,
Dimethylsilylenebis (2-isopropyl-4-phenylazurenyl) zirconium dichloride,
Dimethylsilylenebis {2-ethyl-4- (2-fluorobiphenyl) azurenyl} zirconium dichloride,
Examples include dimethylsilylene bis {2-ethyl-4- (4-t-butyl-3-chlorophenyl) azurenyl} zirconium dichloride.
A compound in which the silylene group of these specific examples is replaced with a germylene group and zirconium is replaced with hafnium is also exemplified as a suitable compound. In addition, since the catalyst component is not an important element of the present invention, it avoids complicated listing and is limited to a representative example, but it is obvious that the effective range of the present invention is not limited thereby. It is.

Ingredient (y)
As the component (y), at least one solid component selected from the components (y-1) to (y-4) described above is used. Each of these components is a known component, and can be appropriately selected from known technologies and used. Specific examples and manufacturing methods thereof are described in detail in JP-A No. 2002-284808, JP-A No. 2002-53609, JP-A No. 2002-69116, JP-A No. 2003-105015, and the like.
Here, as the particulate carrier used for the component (y-1) and the component (y-2), inorganic oxides such as silica, alumina, magnesia, silica alumina, silica magnesia, magnesium chloride, magnesium oxychloride, chloride Examples thereof include inorganic halides such as aluminum and lanthanum chloride, and porous organic carriers such as polypropylene, polyethylene, polystyrene, styrene divinyl benzene copolymer, and acrylic acid copolymer.

Further, as a non-limiting specific example of the component (y), as the component (y-1), a fine particle carrier on which methylalumoxane, isobutylalumoxane, methylisobutylalumoxane, aluminum butylboronate tetraisobutyl, etc. are supported As component (y-2), triphenylborane, tris (3,5-difluorophenyl) borane, tris (pentafluorophenyl) borane, triphenylcarbonium tetrakis (pentafluorophenyl) borate, N, N-dimethyl Particulate carrier carrying anilinium tetrakis (pentafluorophenyl) borate, etc. as component (y-3), alumina, silica alumina, magnesium chloride, etc. as component (y-4), montmorillonite, zakonite, beidellite , Nontronic , Saponite, hectorite, stevensite, bentonite, smectite group such as taeniolite, vermiculite, and the like mica group. These may form a mixed layer.
Particularly preferred among the above components (y) is the ion-exchange layered silicate of component (y-4), and more preferred are chemical treatments such as acid treatment, alkali treatment, salt treatment, and organic matter treatment. It is an ion exchange layered silicate applied.

Ingredient (z)
Examples of the organoaluminum compound used as the component (z) as necessary include the following general formula AlR _a X _3-a
(Wherein R is a hydrocarbon group having 1 to 20 carbon atoms, X is hydrogen, halogen, alkoxy group, a is a number of 0 <a ≦ 3)
Or a trialkylaluminum such as trimethylaluminum, triethylaluminum, tripropylaluminum or triisobutylaluminum, or a halogen or alkoxy-containing alkylaluminum such as diethylaluminum monochloride or diethylaluminum monomethoxide. In addition, aluminoxanes such as methylaluminoxane can also be used.
Of these, trialkylaluminum is particularly preferred.

The catalyst is formed by bringing the component (x), the component (y) and, if necessary, the component (z) into contact with each other. The contact method is not particularly limited, but the contact can be made in the following order. Moreover, this contact may be performed not only at the time of catalyst preparation but also at the time of prepolymerization with olefin or at the time of polymerization of olefin.
(I) Component (x) is contacted with component (y) (ii) Component (x) is contacted with component (y), and then component (z) is added (iii) Component (x) and component (z) ) Is added and then component (y) is added. (Iv) Component (y) and component (z) are contacted and then component (x) is added. (V) The three components are contacted simultaneously.

The amount of components (x), (y) and (z) used in the present invention is arbitrary. For example, the amount of component (x) used relative to component (y) is preferably in the range of 0.1 to 1,000 μmol, particularly preferably 0.5 to 500 μmol, relative to 1 g of component (y). The amount of component (z) used relative to component (y) is preferably such that the amount of transition metal is 0.001 to 100 μmol, particularly preferably 0.005 to 50 μmol, relative to 1 g of component (z). Therefore, the amount of the component (z) to the component (x) is preferably in the range of 10 ⁻⁵ to 50, particularly preferably 10 ^{−4 to} 5 in terms of the molar ratio of the transition metal.

It is preferable that the catalyst of the present invention is subjected to a prepolymerization treatment comprising a small amount of polymerization by contacting an olefin in advance. The olefin to be used is not particularly limited, but ethylene, propylene, 1-butene, 1-hexene, 1-octene, 4-methyl-1-pentene, 3-methyl-1-butene, vinylcycloalkane, styrene and the like can be used. It is possible to use, and it is particularly preferable to use propylene.
The olefin can be supplied by any method, such as a supply method for maintaining the olefin at a constant speed or in a constant pressure state, a combination thereof, or a stepwise change. The temperature and time of the prepolymerization are not particularly limited, but are preferably in the range of −20 ° C. to 100 ° C. and 5 minutes to 24 hours, respectively. The amount of prepolymerization is preferably 0.01 to 100, more preferably 0.1 to 50 with respect to the component (y). After completion of the prepolymerization, the catalyst can be used as it is, depending on the usage form of the catalyst, but may be dried if necessary.
Furthermore, a polymer such as polyethylene, polypropylene, or polystyrene, or an inorganic oxide solid such as silica or titania can be allowed to coexist during or after the contact of the above components.

In order to produce the propylene-ethylene block copolymer (A) used in the present invention, a crystalline propylene homopolymer or a crystalline propylene-ethylene random copolymer component (A1) and a low crystalline or amorphous material are used. It is necessary to sequentially polymerize the propylene-ethylene random copolymer component (A2).
When the propylene-ethylene block copolymer is a random copolymer obtained by simply copolymerizing ethylene with propylene, if the ethylene content is low, the flexibility and impact resistance are not sufficient, so that these physical properties can be improved. Increasing the ethylene content not only makes the heat resistance extremely poor and difficult to manufacture, but also makes it difficult to meet all required qualities.
Therefore, in the present invention, the propylene-ethylene block copolymer is a block copolymer obtained by sequentially polymerizing components having different ethylene contents in the first step and the second step in order to balance all of flexibility and heat resistance. Is necessary.
Further, since a copolymer having a low molecular weight and easily sticking alone may be used as the component (A2), the component (A2) is polymerized after the component (A1) is polymerized in order to prevent problems such as adhesion to the reactor. It is desirable to use a method of polymerizing).

(I) Sequential polymerization In producing the component propylene-ethylene block copolymer (A) of the present invention, the propylene homopolymer or the crystalline propylene-ethylene random copolymer component (A1) and the low crystalline or amorphous The propylene-ethylene random copolymer component (A2) is sequentially polymerized for the reasons described above.
When performing sequential polymerization, either a batch method or a continuous method can be used, but it is generally desirable to use a continuous method from the viewpoint of productivity.
In the case of a batch method, it is possible to polymerize component (A1) and component (A2) separately using a single reactor by changing the polymerization conditions with time. As long as the effects of the present invention are not impaired, a plurality of reactors may be connected in parallel.
In the case of a continuous process, since it is necessary to polymerize component (A1) and component (A2) separately, it is necessary to use a production facility in which two or more reactors are connected in series, but this does not impair the effects of the present invention. As long as each of the component (A1) and the component (A2) is used, a plurality of reactors may be connected in series and / or in parallel.

(Ii) Polymerization process As the polymerization process (polymerization method), any polymerization method such as a slurry method, a bulk method, and a gas phase method can be used. Although supercritical conditions can be used as intermediate conditions between the bulk method and the gas phase method, they are substantially the same as the gas phase method, and are therefore included in the gas phase method without particular distinction.
Since the low crystalline or amorphous propylene-ethylene random copolymer component (A2) is easily soluble in organic solvents such as hydrocarbons and liquefied propylene, it is desirable to use a gas phase method for the production of the component (A2).
There is no particular problem in using any process for the production of the crystalline propylene-ethylene random copolymer component (A1). In order to avoid this problem, it is desirable to use a gas phase method.
Therefore, using a continuous method, first, a propylene homopolymer or a crystalline propylene-ethylene random copolymer component (A1) is polymerized by a bulk method or a gas phase method, followed by low crystalline or amorphous propylene-ethylene. It is most desirable to polymerize the random copolymer elastomer component (A2) by a gas phase method.

(Iii) Other polymerization conditions The polymerization temperature can be used without any particular problem as long as it is within a commonly used temperature range. Specifically, a range of 0 ° C. to 200 ° C., more preferably 40 ° C. to 100 ° C. can be used. The polymerization pressure varies depending on the process to be selected, but can be used without any problem as long as it is in a pressure range usually used. Specifically, a range of greater than 0 to 200 MPa, more preferably 0.1 MPa to 50 MPa can be used. At this time, an inert gas such as nitrogen can be coexisted.
In the case where the sequential polymerization of the component (A1) in the first step and the component (A2) in the second step is performed, it is desirable to add a polymerization inhibitor into the system in the second step. In the case of producing a propylene-ethylene block copolymer, if a polymerization inhibitor is added to a reactor that performs ethylene-propylene random copolymerization in the second step, the particle properties (fluidity, etc.) of the resulting powder, gel, etc. Product quality can be improved. Various technical studies have been made on this technique, and examples thereof include Japanese Patent Publication Nos. 63-54296, 7-25960, and 2003-2939. It is desirable to apply the method to the present invention.

  In addition, each element of the propylene-ethylene block copolymer (A) used for the polypropylene film of the present invention is controlled as follows, and is required for the propylene-ethylene block copolymer (A) of the present invention. Can be manufactured to meet the structural requirements.

(A) Component (A1) For the crystalline propylene-ethylene random copolymer component (A1), it is necessary to control the ethylene content ([E] _A1 ) and T (A1).
In the present invention, in order to control [E] _A1 within a predetermined range, the amount ratio of propylene and ethylene supplied to the polymerization tank in the first step may be appropriately adjusted. The relationship between the supply ratio and the ethylene content in the resulting propylene-ethylene random copolymer varies depending on the type of metallocene catalyst used, but the component (A1) having an ethylene content [E] _A1 required by adjusting the supply ratio Can be manufactured. For example, when [E] _A1 is controlled to 0 to 7 wt%, the supply weight ratio of ethylene to propylene may be in the range of 0 to 0.3, preferably in the range of 0 to 0.2.
At this time, the component (A1) has a narrow crystallinity distribution, and T (A1) decreases with an increase in [E] _A1 . Therefore, in order for T (A1) to satisfy the scope of the present invention, [E] _A1 and the relationship between these are grasped and adjusted to take the target range.

(B) Component (A2) Regarding the low crystalline or amorphous propylene-ethylene random copolymer component (A2), the ethylene content [E] _A2 , the peak temperature T (A2), the xylene-soluble intrinsic viscosity [ [η] cxs needs to be controlled.
In the present invention, in order to control [E] _A2 within a predetermined range, the ratio of ethylene supply to propylene in the second step may be controlled in the same manner as [E] _A1 . For example, when [E] _A2 is controlled to 5 to 20% by weight, the supply weight ratio of ethylene to propylene may be in the range of 0.01 to 5, preferably in the range of 0.05 to 2. At this time, although the crystallinity distribution of the component (A2) is slightly increased with the increase of the ethylene content, T (A2) is decreased with the increase of [E] _A2 as in the case of the component (A1).
Therefore, in order for T (A2) to satisfy the scope of the present invention, the relationship between [E] _A2 and T (A2) is grasped, and [E] _A2 is controlled to be within a predetermined range. Good.
[Η] cxs will be described later.

(C) About W (A1) and W (A2) The amount W (A1) of component (A1) and the amount W (A2) of component (A2) are the production amounts of the first step for producing component (A1). It can be controlled by changing the ratio of the production amount of the component (A2). For example, in order to increase W (A1) and decrease W (A2), the production amount of the second step may be reduced while maintaining the production amount of the first step, which shortens the residence time of the second step. It can be easily controlled by lowering the polymerization temperature or increasing the amount of the polymerization inhibitor. The reverse is also true.
When actually setting the conditions, it is necessary to consider the activity decay. That is, in the range of the ethylene contents [E] _A1 and [E] _A2 to be carried out in the present invention, generally, when the ratio of ethylene supply to propylene is increased in order to increase the ethylene content, the polymerization activity is increased. The activity decay tends to increase. Therefore, in order to maintain the activity of the second step, it is necessary to suppress the polymerization activity of the first step. Specifically, the production amount W (A1) is lowered in the first step, and the polymerization is performed as necessary. Lower the temperature and / or shorten the polymerization time (residence time), or increase the ethylene content [E] _A2 in the second step, increase the production W (A2), and raise the polymerization temperature as necessary And / or conditions may be set in such a way as to increase the polymerization time (residence time).

(D) Glass transition temperature Tg In the propylene-ethylene block copolymer (A) used in the present invention, the glass transition temperature Tg needs to have a single peak. In order for Tg to have a single peak, the difference [E] gap between the ethylene content [E] _A1 in component (A1) and the ethylene content [E] _A2 in component (A2), ie, [E ] _A2- [E] If _A1 is 20% by weight or less, preferably 18% by weight, more preferably 15% by weight or less, and [E] gap is reduced to a range where Tg becomes a single peak in actual measurement. Good.
Depending on the ethylene content [E] _A1 of the crystalline copolymer component (A1), the ethylene content [E] _A2 of the low crystalline or amorphous copolymer component (A2) should be within the proper range. By setting the supply weight ratio of ethylene to propylene during the polymerization of component (A2), it is possible to obtain a polymer having a predetermined [E] gap.
The Tg of the block copolymer which does not take a phase separation structure as in the present invention is the ethylene content [E] _A1 in the component (A1) and the ethylene content [E] _A2 in the component (A2), and It is affected by the ratio of both components. In the present invention, the amount of the component (A2) is 5 to 70% by weight, but in this range, Tg is more strongly affected by the ethylene content [E] _{A2 in} the component (A2). That is, Tg reflects the glass transition of the amorphous part, whereas in the block copolymer component (A) of the present invention, the component (A1) has crystallinity and relatively few amorphous parts, This is because component (A2) is low crystalline or amorphous and most of it is an amorphous part.
Therefore, the value of Tg is controlled by substantially _{[E] A2,} the control method of _{[E] A2} are as described above.

(E) Melt Flow Rate (MFR) In the propylene-ethylene block copolymer (A) of the present invention, the crystalline copolymer component (A1) and the low crystallinity or Since the amorphous copolymer elastomer component (A2) is compatible, the viscosity [η] A1 of the component (A1), the viscosity [η] A2 of the component (A2), a propylene-ethylene block copolymer ( A) The apparent viscosity mixing rule generally holds between the overall viscosity [η] W. That is,
Log [η] W = {W (A1) × Log [η] A1 + W (A2) × Log [η] A2} / 100
Is generally established. In general, there is a certain correlation between MFR and [η], so from the viewpoint of flexibility and heat resistance, [η] A2, W (A1), and W (A2) are set first. The MFR can be freely controlled by changing [η] A1 according to the above equation.

(F) About the elution temperature T (A4) The temperature T (A) at which 99% by weight is eluted is an index indicating the crystallinity distribution. Since T (A4) is closer to T (A1) (lower) as the crystallinity distribution of component (A1) is narrower, controlling (A4) to be lower is the crystal of component (A1) and component (A2). It is none other than controlling the sex distribution narrowly.
In general, by using a metallocene catalyst, a polymer having a narrower crystallinity distribution can be obtained than when using a Ziegler-Natta catalyst. In order to narrow the property distribution, a metallocene catalyst is used.

  Furthermore, in order to adjust the final propylene-ethylene block copolymer (A) to those having desirable physical properties, the component (A1) and the component (A2) must have different specific polymer compositions. is there. That is, in the first step and the second step, it is necessary to keep the polymerization conditions corresponding to the respective polymer compositions, particularly the monomer gas composition, at different specific values. Therefore, when the crystallinity distribution of the component (A2) is wide in the adopted process, the transfer step is adjusted so that the specific monomer gas mixture corresponding to the first step is not brought into the second step from the first step. It is necessary to devise such as. Specifically, the crystallinity distribution of the component (A2) can be narrowed by increasing the purge amount in the transfer step, or by diluting or substituting with an inert gas such as nitrogen.

(G) Component W having a molecular weight of 5,000 or less (Mw ≦ 5,000) Generally, a polymer having a narrower molecular weight distribution than that of a Ziegler-Natta catalyst can be obtained by using a metallocene catalyst. However, in a system that performs sequential polymerization as in the present invention, it is not always sufficient to use a metallocene catalyst in order to narrow the molecular weight distribution. In particular, in order to prevent the formation of low molecular weight components, the time for transferring from the first step to the second step can be shortened, or the monomer gas mixture corresponding to the first step can be replaced with an inert gas such as nitrogen in the transfer step. By completely substituting, W (Mw ≦ 5,000) can be controlled to be small independently of the polymerization conditions.

(H) Intrinsic Viscosity [η] cxs For [η] cxs, the propylene-ethylene block copolymer (A) of the present invention uses a metallocene catalyst, so that the CXS component is mostly contained in the component (A1). Therefore, it can be controlled by changing the molecular weight of the component (A2). In order to control [η] cxs, the ratio of hydrogen supply to the monomer in the second step may be controlled as usual. In general, a metallocene catalyst tends to have a lower molecular weight of the polymer as the polymerization temperature is higher. Therefore, it is possible to control [η] cxs by changing the polymerization temperature. [Η] cxs can also be controlled by combining both the hydrogen supply ratio and the polymerization temperature.

2. Adhesive layer In the surface protective film of the present invention, an adhesive layer is formed on one surface of the base material layer made of the propylene-ethylene block copolymer (A).
A soft polypropylene resin (B) is used as the adhesive.
The soft polypropylene resin (B) is not particularly limited as long as the effects of the present invention are not impaired, and may be a crystalline soft polypropylene resin or an amorphous soft polypropylene resin.
The soft polypropylene resin (B) used in the present invention has the following characteristics (b1) to (b4).

(B1) Melt flow rate The melt flow rate (MFR) of the soft polypropylene resin used in the present invention is 2 to 30 g / 10 min, preferably 3 to 20 g / 10 min, more preferably 3 to 15 g / 10. Minutes.
When the melt flow rate (MFR) is less than 2 g / 10 minutes, the melt viscosity is too high, making it difficult to form a film. Arise.
In addition, a melt flow rate (MFR: unit g / 10min) is a value measured on the same conditions as the propylene-ethylene block copolymer used for the said base material layer.

(B2) Density The density of the soft polypropylene resin used in the present invention is 0.85 to 0.89 g / cm ³ , preferably 0.86 to 0.88 g / cm ³ .
If the density is less than 0.85 g / cm ³ , the adhesive strength becomes too strong and adhesive residue is generated on the adherend, and if it exceeds 0.89 g / cm ³ , the adhesive strength required for the adhesive layer is not expressed. The density is preferably 0.86 to 0.88 g / cm ³ from the balance of adhesive residue and adhesive strength.
In addition, a density is the value measured based on JIS-K6922-2: 1997 appendix (23 degreeC).

(B3) Ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) Ratio of weight average molecular weight (Mw) and number average molecular weight (Mn) of the soft polypropylene resin used in the present invention (Mw / Mn) Is from 1.5 to 3, preferably from 1.7 to 2.5.
When the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is less than 1.5, a stable thickness cannot be secured when the adhesive layer is laminated. If it exceeds 3, there is a problem that powder blowing due to bleed-out occurs and the adherend is contaminated.
Here, Mw / Mn is defined by the ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography (GPC). The measuring method of Mw / Mn is as follows.
Apparatus: Waters GPC 150C type Detector: MIRAN 1A infrared spectrophotometer (measurement wavelength, 3.42 μm)
Column: AD806M / S manufactured by Showa Denko Co., Ltd. (column calibration is performed by Tosoh monodisperse polystyrene (0.5 mg / ml solution of each of A500, A2500, F1, F2, F4, F10, F20, F40, and F288) Measurement was performed, and the logarithm of the elution volume and the molecular weight was approximated by a quadratic equation. The molecular weight of the sample was converted to polyethylene using the viscosity formula of polystyrene and polyethylene. Here, the coefficients of the viscosity formula of polystyrene are α = 0.723 and log K = −3.767, and polyethylene has α = 0.723 and log K = −3.407.
Measurement temperature: 140 ° C
Injection volume: 0.2ml
Concentration: 20 mg / 10 mL
Solvent: Orthodichlorobenzene Flow rate: 1.0 ml / min

(B4) Soluble content at −15 ° C. or lower by temperature rising elution fractionation (TREF) method (S- ₁₅ )
The soluble content (S- ₁₅ ) of -15 [deg.] C. or lower measured by the temperature rising elution fractionation (TREF) method of the soft polypropylene resin used in the present invention is 55% by weight or more, preferably 60% by weight or more. More preferably 65% by weight or more.
When the soluble content (S- ₁₅ ) of -15 [deg.] C. or less measured by the temperature rising elution fractionation (TREF) method is less than 55% by weight, the adhesive force required for the adhesive layer is not expressed.
In addition, soluble fraction (S- ₁₅ ) below -15 degreeC by temperature rising elution fractionation (TREF) method was measured and obtained on the same conditions as the propylene-ethylene block copolymer used for the said base material layer. It is a value calculated from the elution curve as a percentage of the total amount of components eluted at −15 ° C.

The soft polypropylene resin used in the present invention is not particularly limited as long as the effects of the present invention are not impaired, but a propylene / α-olefin random copolymer is preferable.
Examples of the α-olefin as the copolymer component include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene and the like. Specific examples of the propylene / α-olefin random copolymer include propylene / ethylene random copolymer, propylene / 1-butene random copolymer, propylene / 1-hexene random copolymer, propylene / ethylene / 1-butene. A copolymer etc. are mentioned. Preferably, a propylene / ethylene random copolymer, a propylene / 1-butene random copolymer, a propylene / ethylene / 1-butene copolymer, and the like are used. From the balance of adhesive force and adhesive residue, a propylene / ethylene random copolymer and a propylene / ethylene / 1-butene copolymer are preferable.
As content of the alpha olefin of a copolymerization component, it is 5 to 40 weight%, Preferably it is 6 to 30 weight%.

Such a soft polypropylene resin can be easily obtained by a known method such as a slurry method using an inert solvent, a solution method, a gas phase method substantially using no solvent, or a bulk polymerization method using a polymerization monomer as a solvent. Can be obtained. It can also be obtained as a commercial product.
As commercially available products of soft polypropylene-based resins, the Tough selenium series manufactured by Sumitomo Chemical Co., Ltd., the VISTAMAXX series manufactured by ExxonMobil Chemical Co., and the Notio series manufactured by Mitsui Chemicals, Inc. are preferably used.

3. Release treatment layer In the surface protective film of the present invention, a release treatment layer is formed on the other surface of the pressure-sensitive adhesive layer formed on one of the base material layers made of the propylene-ethylene block copolymer. By using a layer formed of a silicone-based or long-chain alkyl-based release treatment agent (C) as the release treatment layer, the roll is unwound from the roll winding state where both the adhesive layer and the release treatment layer are in contact with each other in a solid state. Sometimes the film can be peeled off smoothly, and when used, it can be made into a film for surface protection having the characteristics that the drawability is improved. Moreover, since it is possible to improve the feedability without roughening the surface of the release treatment layer, it is possible to obtain a surface protective film while maintaining excellent transparency.

As the silicone-based release treatment agent used in the layer formed of the silicone-based or long-chain alkyl release treatment agent, a commonly used silicone-based release treatment agent mainly composed of dimethylpolysiloxane can also be used. It is also possible to use a silicone release treatment agent containing a three-dimensional organopolysiloxane.
Specifically, a silicone-based release treatment agent containing organopolysiloxane as a main component and blended with cellulose derivatives such as methyl cellulose, ethyl cellulose, acetyl cellulose, alkyd resin, or the like is preferably used. By blending a cellulose derivative, an alkyd resin, or the like, the release processability of the silicone release treatment agent can be controlled. The cellulose derivative and alkyd resin are preferably blended in an amount of 5 to 50% by weight in the silicone-based release treatment agent.

Organopolysiloxanes are roughly classified into a condensation reaction type and an addition reaction type depending on the type of curing reaction (crosslinking reaction). In the present invention, any reaction type may be used.
For example, as the condensation reaction type silicone release treatment agent, for example, a silicone release treatment agent in which a cellulose derivative or an alkyd resin is blended with an organopolysiloxane having a silanol group at a molecular end can be mentioned. Here, as the organopolysiloxane having a silanol group at the molecular end, a polysiloxane in which an alkyl group such as a methyl group or an ethyl group or a phenyl group is introduced as a side chain functional group (eg, dimethyl diphenylpolysiloxane) is used. It is preferable that the release treatment agent has a good compatibility with the cellulose derivative and the alkyd resin, and a stable release property. In addition, the organopolysiloxane having a silanol group at the molecular end is appropriately blended with a crosslinking agent such as an alkoxy group-containing organopolysiloxane, or a catalyst such as dibutyltin dilaurate, dibutyltin diacetate, dibutyltin dioctate, or zinc octylate. May be.
Moreover, resin, such as an acrylic resin, can also be suitably mix | blended as a 3rd component as needed.
In the silicone release treatment agent, the cross-linking agent is preferably 4 to 20% by weight, the catalyst is preferably 5 to 10% by weight, and the resin as the third component is preferably 5 to 26% by weight.

As an addition reaction type silicone release treatment agent, for example, a silicone release treatment in which a cellulose derivative or alkyd resin is blended with an organopolysiloxane having at least two alkenyl groups such as vinyl groups bonded to silicon atoms in one molecule. Agents.
Here, as the above-mentioned organopolysiloxane, it is preferable to use an organopolysiloxane having an alkyl group such as a methyl group or an ethyl group or a phenyl group introduced as a functional group of the side chain, whereby cellulose derivatives or alkyds are used. A release treatment agent having good compatibility with the resin and stable release characteristics can be obtained. The organopolysiloxane may be appropriately blended with a crosslinking agent such as an organohydrodiene polysiloxane and a catalyst such as a platinum compound such as chloroplatinic acid.

  The silicone-based release treatment agent can be appropriately selected from commercially available products. For example, as a condensation reaction type silicone release treatment agent, KS available from Shin-Etsu Chemical Co., Ltd. -723A / B (consisting of dimethyl diphenylpolysiloxane, methoxysilicone and ethylcellulose) is X-62-9201A / B available from Shin-Etsu Chemical Co., Ltd. as an addition reaction type silicone release treatment agent. be able to.

In addition, as a long-chain alkyl release agent used in a layer formed of a silicone-based or long-chain alkyl release agent, a polymerization of a long-chain alkyl acrylate preferably having a long-chain alkyl group having 12 or more carbon atoms Release agent obtained from a reaction product obtained by reacting a long chain alkyl component such as a long chain alkyl isocyanate with a polyvinyl alcohol, or a copolymer of a long chain alkyl acrylate and another vinyl monomer Is mentioned. Here, the long-chain alkyl preferably refers to a long-chain alkyl group having 12 or more carbon atoms, and the preferable upper limit of the carbon number is preferably about 22 carbon atoms. Examples of (meth) acrylates having a long-chain alkyl group include lauryl methacrylate), myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like.
As specific examples of the long-chain alkyl release agent, for example, Nitto Denko Corporation trade name BP type, Ashio Sangyo Co., Ltd. trade name Ashioresin, on the other hand, Oji Oil Co., Ltd. trade name Pyroyl can be used.
In addition, the formation of the release treatment layer includes a method of forming a release treatment layer by applying a silicone-based or long-chain alkyl release agent, but considering the adhesion with the base material layer, the above-mentioned propylene- A release treatment agent can be blended with the ethylene block copolymer (A) and used as a release treatment layer. When blending and using the above-mentioned release treatment agent in a propylene-ethylene block copolymer, when the total of the propylene-ethylene block copolymer and the release treatment agent is 100% by weight, the content of the propylene-ethylene block copolymer The amount is 99 to 99.95% by weight, and the content of the release treatment agent is 1 to 0.05% by weight.

4). Resin compounding agent that can be used in each layer The base material layer made of the propylene-ethylene block copolymer, the adhesive layer made of a soft polypropylene-based resin, and the release treatment layer in the present invention have a film-forming stability, a secondary Various additives used as known resin compounding agents, for example, antioxidants, antiblocking agents, slips, as long as the purpose of the present invention is not impaired from handling during processing and maintaining the quality as a surface protective film An agent, a nucleating agent, a neutralizing agent, a light stabilizer, an antistatic agent, a tackifier, and the like may be contained. Various additives are described in detail below.

(1) Antioxidants As antioxidants, specific examples of phenolic antioxidants include tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, 1,1,3- Tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis {3- ( 3,5-di-tert-butyl-4-hydroxyphenyl) propionate}, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene 3,9-bis [2- {3- (3-t-butyl-4-hydroxy-5-methylphenyl) propionyloxy} -1,1-dimethylethyl] -2,4,8,10- Examples thereof include tetraoxaspiro [5,5] undecane, 1,3,5-tris (4-t-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanuric acid and the like.

Specific examples of phosphorus antioxidants include tris (mixed, mono and dinonylphenyl phosphite), tris (2,4-di-t-butylphenyl) phosphite, 4,4′-butylidenebis (3- Methyl-6-tert-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl-4-di-tridecylphosphite-5-tert-butylphenyl) butane, bis (2, 4-di-t-butylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-t -Butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phos You can list s fights.
Specific examples of the sulfur-based antioxidant include di-stearyl-thio-di-propionate, di-myristyl-thio-di-propionate, pentaerythritol-tetrakis- (3-lauryl-thio-propionate), and the like. it can.
These antioxidants can be used singly or in combination of two or more as long as the effects of the present object are not impaired.

  The compounding quantity of antioxidant is 0.01-1.0 weight part with respect to 100 weight part of each resin used for each layer of a base material layer, an adhesion layer, and a peeling process layer, Preferably it is 0.02-0. 5 parts by weight, more preferably 0.05 to 0.1 parts by weight. When the blending amount of the antioxidant is within the above range, the thermal stability is improved and the deterioration of the resin causing fish eyes is suppressed.

(2) Antiblocking agent As the antiblocking agent, an average particle diameter of 1 to 7 μm, preferably 1 to 5 μm, and more preferably 1 to 4 μm can be preferably used. If the average particle diameter is less than 1 μm, the slipperiness and openability of the resulting film are inferior. On the other hand, if it exceeds 7 μm, the transparency and scratching property are remarkably inferior. Here, the average particle diameter is a value obtained by Coulter counter measurement.

Specific examples of the anti-blocking agent include, for example, inorganic or synthetic silica (silicon dioxide), magnesium silicate, aluminosilicate, talc, zeolite, aluminum borate, calcium carbonate, calcium sulfate, barium sulfate, calcium phosphate. Etc. are used.
Moreover, as an organic type, polymethyl methacrylate, polymethylsilyltosesquioxane (silicone), polyamide, polytetrafluoroethylene, epoxy resin, polyester resin, benzoguanamine / formaldehyde (urea resin), phenol resin, etc. may be used. it can.
In particular, synthetic silica and polymethyl methacrylate are preferable from the balance of dispersibility, transparency, blocking resistance, and scratch resistance.
The anti-blocking agent may be surface-treated, and as the surface treating agent, surfactant, metal soap, acrylic acid, oxalic acid, citric acid, tartaric acid and other organic acids, higher alcohols, esters, Condensed phosphates such as silicone, fluororesin, silane coupling agent, sodium hexametaphosphate, sodium pyrophosphate, sodium tripolyphosphate, sodium trimetaphosphate, etc. can be used, especially those treated with citric acid among organic acids Is preferred. The treatment method is not particularly limited, and a known method such as surface spraying or dipping can be employed.
The anti-blocking agent may have any shape, and can be any shape such as a spherical shape, a square shape, a columnar shape, a needle shape, a plate shape, and an indefinite shape.
These anti-blocking agents can be used singly or in combination of two or more in a range that does not impair the effects of this object.

  When the antiblocking agent is blended, the blending amount is 0.01 to 1.0 part by weight with respect to 100 parts by weight of each resin used in each of the base layer, the adhesive layer and the release treatment layer, preferably 0.00. It is 05-0.7 weight part, More preferably, it is 0.1-0.5 weight part. When the blending amount of the anti-blocking agent is within the above range, the blocking property is improved and the feeding property is improved.

(3) Slip agent Examples of the slip agent include monoamides, substituted amides, bisamides, and the like, which can be used alone or in combination of two or more.
Specific examples of monoamides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like as saturated fatty acid monoamides.
Examples of the unsaturated fatty acid monoamide include oleic acid amide, erucic acid amide, ricinoleic acid amide and the like.
Specific examples of substituted amides include N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide Etc.
Specific examples of bisamides include, as saturated fatty acid bisamides, methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bis stearic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, Ethylene bisbehenic acid amide, hexamethylene bis stearic acid amide, hexamethylene bis behenic acid amide, hexamethylene bishydroxy stearic acid amide, N, N'-distearyl adipic acid amide, N, N'-distearyl Sepacic acid amide and the like can be mentioned.
Examples of the unsaturated fatty acid bisamide include ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N, N′-dioleyl adipic acid amide, N, N′-dioleyl sepasin acid amide and the like.
Examples of the aromatic bisamide include m-xylylene bis stearic acid amide and N, N′-distearylisophthalic acid amide.
Among these, oleic acid amide, erucic acid amide, and behenic acid amide are particularly preferably used among the fatty acid amides.

  The amount of the slip agent to be blended is 0.01 to 1.0 part by weight, preferably 0 with respect to 100 parts by weight of each resin used for each of the base layer, the adhesive layer and the release treatment layer. 0.05 to 0.7 parts by weight, more preferably 0.1 to 0.4 parts by weight. When the blending amount of the slip agent is within the above range, the slipping property is improved and the feeding property is improved.

(4) Nucleating agent Specific examples of the nucleating agent include sodium 2,2-methylene-bis (4,6-di-t-butylphenyl) phosphate, talc, 1,3,2,4-di (p-methyl). A sorbitol compound such as benzylidene) sorbitol, hydroxy-di (t-butylaluminum benzoate), 2,2-methylene-bis (4,6-di-t-butylphenyl) phosphoric acid and an aliphatic mono-carbon having 8 to 20 carbon atoms. Examples thereof include a carboxylic acid lithium salt mixture (manufactured by ADEKA, trade name NA21).
The blending amount when blending the nucleating agent is 0.0005 to 0.5 parts by weight, preferably 100 parts by weight of each resin used in each layer of the base material layer, the adhesive layer and the release treatment layer. 0.001 to 0.1 parts by weight, more preferably 0.005 to 0.05 parts by weight. When the blending amount of the nucleating agent is within the above range, the crystallization speed is increased and the transparency is improved.

Moreover, a high density polyethylene resin can be mentioned as a nucleating agent other than the above. The density of the high-density polyethylene resin is 0.94 to 0.98 g / cm ³ , preferably 0.95 to 0.97 g / 10 cm ³ . If the density is out of this range, the effect of improving transparency cannot be obtained. The 190 degreeC melt flow rate (MFR) of a high density polyethylene resin is 5 g / 10min or more, Preferably it is 7-500 g / 10min, More preferably, it is 10-100 g / 10min. When the MFR is less than 5 g / 10 min, the dispersion diameter of the high-density polyethylene resin is not sufficiently small, and it itself becomes a foreign matter and causes fish eyes. In order to finely disperse the high-density polyethylene resin, the MFR of the high-density polyethylene resin is preferably larger than the MFR of the propylene-ethylene block copolymer of the present invention.

  The production of the high-density polyethylene resin used as the nucleating agent is not particularly limited with respect to the polymerization method and catalyst as long as a polymer having the desired physical properties can be produced. For catalysts, Ziegler type catalysts (ie, based on a combination of supported or unsupported halogen-containing titanium compounds and organoaluminum compounds), Kaminsky type catalysts (ie, supported or unsupported metallocene compounds and organoaluminum compounds, especially alumoxanes). Based on the combination). There is no restriction | limiting about the shape of a high density polyethylene-type resin, A pellet form may be sufficient and a powder form may be sufficient.

  When used as a nucleating agent, the blending amount of the high-density polyethylene is 0.01 to 5 parts by weight, preferably 100 parts by weight of each resin used in each layer of the base material layer, the adhesive layer and the release treatment layer. 0.05 to 3 parts by weight, more preferably 0.1 to 1 part by weight. When the blending amount of the high density polyethylene is within the above range, the crystallization speed is increased and the transparency is improved. Further, in the case of coextrusion molding, there is no transfer of the sweeper roll.

(5) Neutralizing agent Specific examples of the neutralizing agent include calcium stearate, zinc stearate, hydrotalcite, Mizukarak (manufactured by Mizusawa Chemical Co., Ltd.), and the like.
The blending amount in the case of blending the neutralizing agent is 0.01 to 1.0 part by weight, preferably 0.00 with respect to 100 parts by weight of each resin used for each of the base layer, the adhesive layer and the release treatment layer. It is 02-0.5 weight part, More preferably, it is 0.05-0.1 weight part. When the blending amount of the neutralizing agent is within the above range, the effect as an internal lubricant is improved, and scraping of deteriorated materials inside the extruder is suppressed.

(6) Light Stabilizer As the light stabilizer, a hindered amine stabilizer is preferably used, and a structure in which all hydrogen bonded to carbons at the 2-position and 6-position of a conventionally known piperidine is substituted with a methyl group. Although the compound which has this is used without being specifically limited, the following compounds are specifically used.
Specific examples include polycondensates of dimethyl oxalate and 1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine, tetrakis (1,2,2,6,6). -Pentamethyl-4-piperidyl) 1,2,3,4-butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, N, N-bis (3-aminopropyl) ) Ethylenediamine · 2,4-bis [N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino] -6-chloro-1,3,5-triazine condensate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, poly [{6- (1,1,3,3-tetramethylbutyl) imino-1,3,5-triazine-2,4- Jil} {(2,2, , 6-tetramethyl-4-piperidyl) imino} hexamethylene {2,2,6,6-tetramethyl-4-piperidyl} imino], poly [(6-morpholino-s-triazine-2,4-diyl) And [(2,2,6,6-tetramethyl-4-piperidyl) imino] hexamethylene {(2,2,6,6-tetramethyl-4-piperidyl) imino}].
These hindered amine stabilizers can be used singly or in combination of two or more in a range not impairing the effect of the present object.

When the hindered amine stabilizer is blended, the blending amount is 0.005 to 2 parts by weight, preferably 0.01 to 100 parts by weight of each resin used in each layer of the base material layer, the adhesive layer and the release treatment layer. -1 part by weight, more preferably 0.05-0.5 part by weight.
When the content of the hindered amine stabilizer is within the above range, stability such as heat resistance and aging resistance is improved.

(7) Antistatic agent The antistatic agent can be used without particular limitation as long as it is a known antistatic agent or antistatic agent conventionally used, and examples thereof include anionic surfactants and cations. Ionic surfactants, nonionic surfactants, amphoteric surfactants and the like.

  Examples of the anionic surfactant include fatty acid or rosin acid soap, N-acyl carboxylate, ether carboxylate, carboxylate such as fatty acid amine salt; sulfosuccinate, ester sulfonate, N-acyl sulfonate Sulfonates such as salts; sulfated oils, sulfate esters, alkyl sulfate salts, sulfate sulfate polyoxyethylene salts, sulfate ether salts, sulfate ester salts such as sulfate amide salts; alkyl phosphate salts, alkyl polyoxyethylene phosphates Examples thereof include phosphoric ester salts such as salts, phosphoric acid ether salts and phosphoric acid amide salts.

  Examples of the cationic surfactant include amine salts such as alkylamine salts; alkyltrimethylammonium chloride, alkylbenzyldimethylammonium chloride, alkyldihydroxyethylmethylammonium chloride, dialkyldimethylammonium chloride, tetraalkylammonium salt, N, N-di Quaternary ammonium salts such as (polyoxyethylene) dialkylammonium salts and N-alkylalkanamide ammonium salts; 1-hydroxyethyl-2-alkyl-2-imidazoline, 1-hydroxyethyl-1-alkyl-2-alkyl Examples include alkyl imidazoline derivatives such as -2-imidazoline; imidazolinium salts, pyridinium salts, isoquinolinium salts, and the like.

  Examples of the nonionic surfactant include ether forms such as alkyl polyoxyethylene ether and p-alkylphenyl polyoxyethylene ether; fatty acid sorbitan polyoxyethylene ether, fatty acid sorbitol polyoxyethylene ether, fatty acid glycerin polyoxyethylene ether, etc. Ether ester form of fatty acid polyoxyethylene ester, monoglyceride, diglyceride, sorbitan ester, sucrose ester, dihydric alcohol ester, boric acid ester, etc .; dialcohol alkylamine, dialcohol alkylamine ester, fatty acid alkanolamide, N, N-di (polyoxyethylene) alkanamide, alkanolamine ester, N, N-di (polyoxyethylene) alkaneamine, amine oxy De, a nitrogen-formed and fabricated and alkyl polyethylene imine.

  Examples of the amphoteric surfactant include amino acid forms such as monoaminocarboxylic acid and polyaminocarboxylic acid; N-alkyl-β-alanine such as N-alkylaminopropionate and N, N-di (carboxyethyl) alkylamine salt. Forms: Betaine forms such as N-alkylbetaines, N-alkylamidobetaines, N-alkylsulfobetaines, N, N-di (polyoxyethylene) alkylbetaines, imidazolinium betaines; 1-carboxymethyl-1-hydroxy- And alkyl imidazoline derivatives such as 1-hydroxyethyl-2-alkyl-2-imidazoline and 1-sulfoethyl-2-alkyl-2-imidazoline.

  Among these, nonionic surfactants and amphoteric surfactants are preferable. Among them, monoglycerides, diglycerides, boric acid esters, dialcohol alkylamines, dialcohol alkylamine esters, amides and the like or nitrogen-containing non-type surfactants are preferred. Ionic surfactants; betaine amphoteric surfactants are preferred.

  In addition, as an antistatic agent, a commercial item can be used, for example, electro stripper TS5 (trade name, glycerin monostearate manufactured by Kao Corporation), electro stripper TS6 (trade name, stearyl manufactured by Kao Corporation). Diethanolamine), electrostripper EA (trade name, lauryl diethanolamine, manufactured by Kao Corporation), electrostripper EA-7 (trade name, polyoxyethylene laurylamine capryl ester, manufactured by Kao Corporation), Denon 331P (maruhishi oil ( Co., Ltd., trademark, stearyl diethanolamine monostearate), Denon 310 (manufactured by Maruhishi Oil Chemical Co., Ltd., trademark, alkyldiethanolamine fatty acid monoester), Register PE-139 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trademark) , Stearic acid mono & diglyceride Ester), Chemistat 4700 (Sanyo Chemical Industries Co., Ltd., trademark, alkyl dimethyl betaine), rheostat S (Lion Co., Ltd., trademark, alkyl diethanolamide), and the like.

  When blending the antistatic agent, the blending amount is 0.01 to 2 parts by weight, preferably 0.05 to 1 with respect to 100 parts by weight of each resin used in the base layer, the adhesive layer and the release treatment layer. Parts by weight, more preferably 0.1 to 0.8 parts by weight, most preferably 0.2 to 0.5 parts by weight. These antistatic agents can be used singly or in combination of two or more in a range that does not impair the effects of this object. When the blending amount of the antistatic agent is within the above range, it is possible to prevent electrification and suppress deposits such as dust.

(8) Tackifier The tackifier includes, for example, aliphatic petroleum resins, alicyclic hydrogenated petroleum resins, aromatic petroleum resins, C5 petroleum resins, terpene resins, coumarone / indene resins, Known tackifiers such as phenol resins, rosin resins, tackifiers, hydrogenated styrene elastomers and the like can be mentioned, and these are used singly or in combination of two or more in a range not significantly impairing the effects of the present invention. be able to. Specific examples of the hydrogenated styrenic elastomer include “Dynalon” series manufactured by JSR Corporation, but are not limited thereto.

  The blending amount in the case of blending the tackifier is not particularly limited as long as the effects of the present invention are not impaired, but 100 weights of each resin used for each of the base layer, the tacky layer and the release treatment layer. 0.0001 to 200 parts by weight with respect to parts. Preferably it is 0.01-150 weight part, More preferably, it is 1-150 weight part, Most preferably, it is 10-100 weight part. When the compounding amount of the tackifier is within the above range, the adhesive strength is improved.

(9) Others Further, an elastomer is blended as a component for appropriately adjusting flexibility and tackiness within a range that does not significantly impair the effects of the present invention, an ultraviolet absorber, a metal deactivator, a peroxide, and a filler. Antibacterial and antifungal agents, fluorescent whitening agents, antifogging agents, flame retardants, colorants, pigments, natural oils, synthetic oils, waxes, and the like can be blended, and the blending ratio is an appropriate amount.

The blending of the above various additives can be directly added to the propylene-ethylene block copolymer of the present invention obtained by polymerization and melt kneaded for use, or may be added during melt kneading. . Furthermore, it can be added directly after melt-kneading, or can be added as a masterbatch within a range that does not significantly impair the effects of the present invention. Moreover, you may add by these composite methods.
In general, additives such as an antioxidant and a neutralizing agent are blended, mixed, melted and kneaded, and then molded into a product for use. It is also possible to add and use other resins or other additional components (including a masterbatch) as long as the effects of the present invention are not significantly impaired during molding.

  For the above mixing, melting, and kneading, any conventionally known method can be used. Usually, a Henschel mixer, a super mixer, a V blender, a tumbler mixer, a ribbon blender, a Banbury mixer, a kneader blender, a uniaxial or biaxial kneading. It can be carried out in an extruder. Among these, it is preferable to perform mixing or melt-kneading with a uniaxial or biaxial kneading extruder.

5. Production of Surface Protection Film The surface protection film of the present invention can be produced by a known method for producing a laminated film.
For example, it manufactures by well-known techniques, such as a T die-cast method, a water cooling inflation method, an air cooling inflation method.
In the T-die casting method, the resin melt-kneaded by an extruder is extruded from the T-die and cooled by being brought into contact with a roll through which a coolant such as water is passed, and generally has good transparency and good thickness accuracy. A film can be produced. Such a method is a preferable manufacturing method for the film.

  Here, the thickness of the surface protective film is not particularly limited, but is preferably 10 to 500 μm, more preferably 20 to 200 μm, still more preferably 30 to 100 μm, and most preferably 40 to 80 μm. If the thickness is outside this range, processing becomes difficult.

As a means of providing the adhesive layer on one side of the base material layer, as a method obtained by application by a solution coating method or the like, an adhesive dissolved in an organic solvent such as a toluene solution is applied to one side of the base material layer by a roll coater or the like Thereafter, a method of forming an adhesive layer by drying can be mentioned. At that time, in order to improve the affinity between the base material layer and the pressure-sensitive adhesive layer, conventionally known corona discharge treatment, plasma discharge treatment, primer treatment, etc. are performed on one surface of the base material layer (adhesion surface with the pressure-sensitive adhesive layer). May be.
In addition, as a method for obtaining the adhesive layer by lamination, the adhesive is heated and melted by an extruder, extruded into a film form from a T die, and laminated on one side of the substrate layer, or the substrate layer is obtained by an extruder. And a method in which the pressure-sensitive adhesive is heated and melted and coextruded into a film shape from a T-die together with the base material layer.
In the present invention, adopting a method in which the adhesive layer is coextruded with the base material layer in the form of a film from a T-die is advantageous in terms of contamination problems and economical points.

  The thickness of the adhesive layer is not particularly limited because the adhesive strength varies depending on the application, but in the case of a method of forming an adhesive layer by applying an adhesive in a later step, the adhesive layer is heated and melted from an extruder. Also in the case of the method of forming a layer, it is 0.1-100 micrometers normally, Preferably it is 1-50 micrometers, More preferably, it is 5-30 micrometers, Most preferably, it is 10-20 micrometers.

Examples of means for forming the release treatment layer provided on the other surface of the pressure-sensitive adhesive layer of the surface protective film of the present invention include known methods such as coating, curing, and lamination.
As a method for obtaining the release treatment layer by coating, a release treatment agent dissolved in an organic solvent such as a toluene solution is applied to one side of the base material layer with a roll coater, and then dried to cure the release treatment agent and release. The method of forming a process layer can be mentioned. At that time, in order to improve the affinity between the base material layer and the release treatment layer, conventionally known corona discharge treatment, plasma discharge treatment, primer treatment, etc. are performed on one side of the base material layer (adhesion surface with the release treatment layer). May be.
In addition, as a method for obtaining a release treatment layer by lamination, a method in which the release treatment layer is heated and melted by an extruder and laminated in a film shape from a T die on one side of a base material layer, or by an extruder, Examples thereof include a method in which the material layer and the release treatment layer are heated and melted and coextruded into a film shape from a T die together with the base material layer.
In the present invention, when a method of coextrusion forming a release treatment layer formed by blending a silicone-based or long-chain alkyl release treatment agent with a propylene-ethylene block copolymer into a film shape from a T-die together with a base material layer, This is advantageous in terms of pollution and economy. Further, when a specific propylene-ethylene block copolymer polymerized from a metallocene catalyst used in the base material layer of the present invention is used as a propylene resin containing a silicone-based or long-chain alkyl-based release treatment agent, It becomes an excellent surface protective film with very few.

The thickness of the release treatment layer is not particularly limited, but in the case of a method of forming a release treatment layer by applying a release treatment agent in a later step, the amount of the release treatment agent applied is usually 0 in the case of a silicone-based material. 0.01 to 10 g / m ² , preferably 0.5 to 0.7 g / m ² , and more preferably 0.1 to 0.4 g / m ² . In the case of long-chain alkyl-based, 0.005~10g / ^{m 2,} preferably 0.02~0.3g / ^{m 2,} particularly preferably preferably 0.01 to 0.1 g / ^{m 2.}
Moreover, in the case of the method of mix | blending a peeling agent with a propylene-type resin and forming the peeling process layer formed by heating and melting from an extruder, it is 0.1-100 micrometers normally, Preferably it is 1-50 micrometers, More preferably, it is 5-30 micrometers. Most preferably, it is 10-20 micrometers.

6). Applications of the surface protective film Applications of the surface protective film of the present invention include all known products that require surface protection. By field, for example, protective films for transporting electronic components and protective films for printed boards Electronics field such as window glass protective film, baking coating film, guard film for protecting automobiles to users, marking film for display, marking film for decoration, sponge film for buffering, protection, heat insulation and soundproofing, etc. Automotive field, medical and hygiene materials field such as adhesive bandages and transdermal patches, and electrical insulation, identification, duct construction, window glass protection, curing, packaging, packaging, office use, home use And housing / construction field such as protective film for fixing, bundling and repair.
Among these, particularly suitable for surface protection of building members such as synthetic resin plates, decorative plates, metal plates, and glass plates, and surface protection of components of liquid crystal display devices such as polarizing plates and retardation plates. Can do.

  Examples of the present invention will be specifically described below, but the present invention is not limited to these examples. The physical property measurement methods, characteristic evaluation methods, and resin materials used in Examples and Comparative Examples are as follows.

1. Physical property measurement method, characteristic evaluation method (1) MFR: Propylene-ethylene block copolymer and soft polypropylene resin were measured at 230 ° C. under a load of 21.18 N in accordance with JIS K-7210-1995.

(2) Density: Measured according to JIS K-6922-2: 1997 appendix (23 ° C.).

(3) Melting peak temperature: Using a differential scanning calorimeter (Seiko DSC), a sample amount of 5.0 mg was taken, held at 200 ° C. for 5 minutes, and then crystallized at a rate of temperature decrease of 10 ° C./min to 40 ° C. And the melting peak temperature (Tmp) when melted at a heating rate of 10 ° C./min was measured.

(4) Weight average molecular weight (Mw), number average molecular weight (Mn): measured by the method described in the explanation of the base material layer and the adhesive layer.

(5) TREF measurement: A sample is dissolved in o-dichlorobenzene (containing 0.5 mg / ml BHT) at 140 ° C. to obtain a solution. This is introduced into a 140 ° C. TREF column, cooled to 100 ° C. at a rate of 8 ° C./min, subsequently cooled to −15 ° C. at a rate of 4 ° C./min, and held for 60 minutes. Thereafter, o-dichlorobenzene (containing 0.5 mg / ml BHT) as a solvent is caused to flow through the column at a flow rate of 1 ml / min, and components dissolved in o-dichlorobenzene at −15 ° C. in the TREF column. Elution is performed for 10 minutes, and then the column is linearly heated to 140 ° C. at a heating rate of 100 ° C./hour to obtain an elution curve.

(A) Apparatus (A-1) TREF part TREF column: 4.3 mmφ × 150 mm stainless steel column Column packing material: 100 μm Surface inactive glass beads )
Temperature distribution: ± 0.5 ° C
Temperature controller: Chino Corporation Digital Program Controller KP1000 (Valve Oven)
Heating method: Air bath oven Measurement temperature: 140 ° C
Temperature distribution: ± 1 ° C
Valve: 6-way valve 4-way valve

(I-2) Sample injection part injection method: loop injection method Injection amount: loop size 0.1 ml
Inlet heating method: Aluminum heat block measurement temperature: 140 ° C
(I-3) Detector detector: fixed wavelength infrared detector MIRAN 1A manufactured by FOXBORO
Detection wavelength: 3.42 μm
High-temperature flow cell: Micro flow cell for LC-IR Optical path length: 1.5 mm Window shape: 2φ x 4 mm long circle Synthetic sapphire window measurement temperature: 140 ° C
(A-4) Pump unit liquid feed pump: SSC-3461 pump (b) manufactured by Senshu Kagaku Co., Ltd. (b) Measurement conditions Solvent: o-dichlorobenzene (including 0.5 mg / ml BHT)
Sample concentration: 5 mg / ml
Sample injection volume: 0.1 ml
Solvent flow rate: 1 ml / min

(6) Measurement of solid viscoelasticity A sample cut into a strip shape of 10 mm width × 18 mm length × 2 mm thickness from a 2 mm thick sheet injection-molded under the following conditions was used. The apparatus used was ARES manufactured by Rheometric Scientific. The frequency is 1 Hz. The measurement temperature was raised stepwise from −60 ° C., and the measurement was performed until the sample melted and became impossible to measure. The strain was performed in the range of 0.1 to 0.5%.
Test piece preparation conditions Standard number: JIS-K7152 (ISO294-1)
Molding machine: TU-15 injection molding machine manufactured by Toyo Machine Metal Co., Ltd. Molding machine set temperature: 80, 80, 160, 200, 200, 200 ° C.
Mold temperature: 40 ℃
Injection speed: 200 mm / sec (speed in the mold cavity)
Injection pressure: 800 kgf / cm ²
Holding pressure: 800 kgf / cm ²
Holding time: 40 seconds Mold shape: Flat plate (thickness 2 mm, width 30 mm, length 90 mm)

(7) Intrinsic viscosity (synonymous with intrinsic viscosity) of normal temperature xylene soluble component (CXS)
A 2 g sample is dissolved in 300 ml of p-xylene (containing 0.5 mg / ml BHT) at 130 ° C. to make a solution, and then left at 23 ° C. for 12 hours. Thereafter, the precipitated polymer is filtered off, p-xylene is evaporated from the filtrate, and further dried under reduced pressure at 100 ° C. for 12 hours, and CXS is collected and weighed. The intrinsic viscosity of the obtained CXS component was measured at 135 ° C. using Decalin as a solvent using an Ubbelohde viscometer.

(8) Calculation of ethylene content It measured by the method described by description of the base material layer.

(9) Haze:
The film was conditioned for 24 hours in an atmosphere of 23 ° C. and 50% RH, and then measured with a haze meter in accordance with JIS-K7136-2000.
The smaller the value obtained, the better the transparency.

(10) Tensile modulus:
The tensile elasticity modulus about the flow direction (MD) of the film was measured according to the following conditions based on ISO527.
The higher the obtained numerical value, the higher the rigidity of the film and the easier it is to handle it as a surface protecting film.
Sample length: 150mm
Sample width: 10mm
Distance between chucks: 100mm
Crosshead speed: 25mm / min

(11) Fisheye:
The film was cut into a size of 20 cm × 15 cm, five films were visually observed, the number of fish eyes was counted, and the number per 1 m ^{2 of} area was calculated. The size of the fish eye is 0.4 mm or more in the major axis (≧ 0.4 mm), 0.2 mm or less smaller than 0.4 mm (<0.4 mm to ≧ 0.2 mm), 0.1 mm or larger smaller than 0.2 mm (< 0.2 mm to ≧ 0.1 mm), and the number of each was divided (unit: pieces / m ² ).
When the number of fish eyes is small, even if the surface protective film is attached to the object to be protected and stacked and stored, the object to be protected does not dent, and is better as the surface protective film.

(12) Tackiness:
Acrylic resin plate (mirror surface acrylic plate (“Acrylite L001” 3 mm plate manufactured by Mitsubishi Rayon Co., Ltd.)) cut into a longitudinal direction of the film, cut to a width of 25 mm and a length of 20 cm, and preheated to 60 ° C. After the pasted film was aged for 12 hours at a temperature of 23 ° C. and a humidity of 50%, the adhesive strength per 25 mm width was measured at a pulling speed of 300 mm / min and a peeling angle of 180 ° C. in accordance with JIS Z0237. Was measured.
The higher the value, the higher the adhesive strength. Although the target strength varies depending on the non-adherent body, the adhesive strength is generally used in the range of 1 to 400 g / 25 mm. If the adhesive strength is too low, bonding to the adherend cannot be performed. If the adhesive strength is too high, it cannot be easily peeled off from the adherend.

(13) Peeling treatment layer-adhesive delamination property:
Usually, the surface protective film is wound around a paper tube in a form in which the release treatment layer and the adhesive layer are in contact with each other, and is used by being fed out and adhered to a product. As an evaluation of unwinding property, the molded film is rolled up in a form in which the release treatment layer and the adhesive layer are in contact with a 3-inch paper tube, and attached to the unwinding machine and smoothed without wrinkles or sagging when unrolled at 20 m / min. It was visually confirmed whether it could be fed out smoothly, and ○ that could be smoothly fed out was marked with ○, and that that could not be smoothly fed out was marked with ×.

(14) Contamination resistance of adherend:
In the adhesive evaluation, when the film was peeled off from the acrylic plate, the case where no peeling marks remained was marked with “◯”, and the case where the peeling marks or the adhesive layer resin remained on the acrylic plate was marked with “x”.

2. Resin Material (1) Base Layer Resin As the propylene-ethylene block copolymer of the base layer resin, the propylene-ethylene block copolymers (PEB-1 to 9) obtained in Production Examples 1 to 9 described later are used. It was.
The polymerization conditions and polymerization results are shown in Table 3, and the physical properties are shown in Table 4.

(Production Example 1)
(I) Preparation of prepolymerization catalyst (a) Chemical treatment of silicate In a 10-liter glass separable flask equipped with a stirring blade, 3.75 liters of distilled water, followed by 2.5 kg of concentrated sulfuric acid (96%) Slowly added. At 50 ° C., 1 kg of montmorillonite (Menzawa Chemical Co., Ltd. Benclay SL; average particle size = 25 μm, particle size distribution = 10-60 μm) was dispersed, heated to 90 ° C., and maintained at that temperature for 6.5 hours. After cooling to 50 ° C., the slurry was filtered under reduced pressure to recover the cake. 7 liters of distilled water was added to this cake to reslurry it, and then filtered. This washing operation was performed until the pH of the washing solution (filtrate) exceeded 3.5. The collected cake was dried at 110 ° C. overnight under a nitrogen atmosphere. The weight after drying was 707 g.
(B) Drying of silicate The silicate previously chemically treated was dried with a kiln dryer. Specifications and drying conditions are as follows.
Rotating cylinder: Cylindrical inner diameter 50 mm Heating zone 550 mm (Electric furnace) Speed with rotating blade: 2 rpm Tilt angle: 20/520 Silicate feed rate: 2.5 g / min Gas flow rate: Nitrogen 96 liters / hour Countercurrent drying Temperature: 200 ° C (powder temperature)

(C) Preparation of catalyst An autoclave having an internal volume of 16 liters having a stirring and temperature control device was sufficiently substituted with nitrogen. To this, 200 g of dry silicate was introduced, 1,160 ml of mixed heptane and 840 ml of a heptane solution of triethylaluminum (0.60 M) were added and stirred at room temperature. After 1 hour, the mixture was washed with mixed heptane to prepare 2,000 ml of silicate slurry. Next, 9.6 ml of a heptane solution of triisobutylaluminum (0.71 ML) was added to the silicate slurry prepared above and reacted at 25 ° C. for 1 hour. In parallel, 187 ml of (r) -dichloro [1,1′-dimethylsilylenebis {2-methyl-4- (4-chlorophenyl) -4H-azurenyl}] zirconium and 2,180 mg (0.3 mM) of mixed heptane Then, 33.1 ml of a heptane solution of triisobutylaluminum (0.71 M) was added and the mixture reacted at room temperature for 1 hour was added to the silicate slurry. After stirring for 1 hour, 5,000 ml was added with mixed heptane. Prepared.

(D) Preliminary polymerization / washing Subsequently, the temperature in the tank was raised by 40 ° C., and when the temperature was stabilized, propylene was supplied at a rate of 100 g / hour to maintain the temperature. After 4 hours, the supply of propylene was stopped and maintained for another 2 hours.
After completion of the prepolymerization, the remaining monomer was purged, the stirring was stopped and the mixture was allowed to stand for about 10 minutes, and then the supernatant was decanted to 2,400 ml. Subsequently, 9.5 ml of a heptane solution of triisobutylaluminum (0.71 ML) and 5600 ml of mixed heptane were further added, stirred at 40 ° C. for 30 minutes, allowed to stand for 10 minutes, and then 5600 ml of the supernatant was removed. This operation was further repeated 3 times. When the component analysis of the final supernatant was performed, the concentration of the organoaluminum component was 1.23 mmol / liter, the Zr concentration was 8.6 × 10 −6 g / L, and the abundance in the supernatant relative to the charged amount was It was 0.016%. Subsequently, 170 ml of a heptane solution of triisobutylaluminum (0.71 ML) was added, followed by drying at 45 ° C. under reduced pressure. A prepolymerized catalyst containing 2.0 g of polypropylene per 1 g of catalyst was obtained.

(Ii) First Step In the first step, propylene-ethylene random copolymerization was carried out using a liquid phase polymerization tank with an agitator having an internal volume of 0.4 m ³ . Liquefied propylene, liquefied ethylene, and triisobutylaluminum were continuously fed at 90 kg / hour, 4.2 kg / hour, and 21.2 g / hour, respectively. The hydrogen supply amount was adjusted so that the MFR in the first step became a target value.
Further, the above prepolymerized catalyst was supplied as a catalyst (excluding the weight of the prepolymerized polymer) so as to be 6.9 g / hour. The polymerization tank was cooled so that the polymerization temperature was 45 ° C.
When the propylene-ethylene random copolymer obtained in the first step was analyzed, BD (bulk density) was 0.46 g / cc, MFR was 7.0 g / 10 min, and ethylene content was 3.7% by weight. It was.

(Iii) Second Step In the second step, propylene-ethylene random copolymerization was carried out using a stirred gas phase polymerization tank having an internal volume of 0.5 m ³ . The slurry containing polymer particles was continuously withdrawn from the liquid phase polymerization tank in the first step, flushed with liquefied propylene, and then pressurized with nitrogen and continuously supplied to the gas phase polymerization tank.
The polymerization tank was controlled so that the temperature was 80 ° C. and the total partial pressure of propylene, ethylene, and hydrogen was 1.5 MPa. At that time, the concentration of propylene, ethylene and hydrogen in the total partial pressure of propylene, ethylene and hydrogen was controlled to be 66.97 vol%, 32.99 vol% and 420 volppm, respectively.
Furthermore, ethanol was supplied to the gas phase polymerization tank as an activity inhibitor. The supply amount of ethanol was set to 0.3 mol / mol with respect to aluminum in TIBA supplied along with the polymer particles supplied to the gas phase polymerization tank.
When the propylene-ethylene block copolymer thus obtained was analyzed, the activity was 8.7 kg / g-catalyst, the BD was 0.41 g / cc, the MFR was 7.0 g / 10 min, and the ethylene content was 8.7. % By weight.

(Iv) Granulation To the propylene-ethylene block copolymer powder obtained above, the following antioxidant was added to a blender, and the mixture was sufficiently stirred and mixed.
Antioxidant: Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane (manufactured by Ciba Specialty Chemicals, Inc., Irganox 1010) 0.05 Parts by weight, tris (2,4-di-t-butylphenyl) phosphite (manufactured by Ciba Specialty Chemicals Co., Ltd., Irgafos 168) 0.10 parts by weight Propylene-ethylene block copolymer with additives After high-speed mixing of the powder at 750 rpm for 1 minute at room temperature using a Henschel mixer, the mixture was melt-kneaded at a screw diameter of 30 mm, a PCM twin screw extruder manufactured by Ikegai Seisakusho at a screw speed of 200 rpm, a discharge rate of 10 kg / hr, and an extruder temperature of 190 ° C. The molten resin extruded from the strand die is drawn while being cooled and solidified in the cooling water tank. The raw material pellet (PEB-1) of a propylene-ethylene block copolymer was obtained by scraping and cutting the strand into a diameter of about 2 mm and a length of about 3 mm using a strand cutter.

(Production Examples 2 to 5)
A propylene-ethylene block copolymer was produced in the same manner as in Production Example 1 except that the polymerization conditions were changed to those shown in Table 3.
From the resulting propylene-ethylene block copolymer powder, raw material pellets (PEB-2 to 5) were obtained under the same additive formulation and granulation conditions as in Production Example 1.

(Production Example 6)
(I) Preparation of solid catalyst component 2,000 ml of dehydrated and deoxygenated n-heptane was introduced into a fully nitrogen-substituted flask, and then 2.6 mol of MgCl ₂ and Ti (On-C ₄ H) were introduced. ₉ ) 5.2 mol of ₄ was introduced and reacted at 95 ° C. for 2 hours. After completion of the reaction, the temperature was lowered to 40 ° C., and then 320 ml of methylhydropolysiloxane (20 centistokes) was introduced and reacted for 3 hours. The resulting solid component was washed with n-heptane.
Next, 4,000 milliliters of n-heptane purified in the same manner as described above was introduced into a sufficiently nitrogen-substituted flask, and 1.46 mol of the solid component synthesized above was introduced in terms of Mg atoms. Next, 25 ml of n-heptane was mixed with 2.62 mol of SiCl ₄ , introduced into the flask at 30 ° C. for 30 minutes, and reacted at 70 ° C. for 3 hours. After completion of the reaction, washing with n-heptane was performed. Next, 0.15 mol of phthalic acid chloride was mixed with 25 ml of n-heptane, introduced into the flask at 70 ° C. for 30 minutes, and reacted at 90 ° C. for 1 hour. After completion of the reaction, washing with n-heptane was performed. Next, 11.4 mol of TiCl ₄ was introduced and reacted at 110 ° C. for 3 hours. After completion of the reaction, the solid component was obtained by washing with n-heptane. The titanium content of this solid component was 2.0% by weight.
Next, an autoclave having an internal volume of 16 liters having a stirring and temperature control device was sufficiently replaced with nitrogen, and 5,000 milliliters of n-heptane purified in the same manner as above was introduced into the autoclave to synthesize the solid component synthesized above. Gram was introduced, and 0.875 mol of SiCl ₄ was introduced and reacted at 90 ° C. for 2 hours. After completion of the reaction, further (CH ₂ ═CH) Si (CH ₃ ) ₃ 0.15 mol, (t-C ₄ H ₉ ) (CH ₃ ) Si (OCH ₃ ) ₂ 0.075 mol and Al (C ₂ H ₅ ) ₃ 0.4 mol was sequentially introduced and contacted at 30 ° C. for 2 hours. After completion of the contact, the catalyst was thoroughly washed with n-heptane to obtain a solid catalyst component mainly composed of magnesium chloride. The titanium content of this product was 1.8% by weight.

(Ii) Prepolymerization An autoclave having an internal volume of 16 liters equipped with a stirring and temperature control device was sufficiently replaced with nitrogen. To this, 100 g of the n-heptane slurry of the solid catalyst component prepared above was introduced as a solid catalyst component, and n-heptane was further introduced to adjust the liquid level to 5,000 ml. Next, the temperature in the tank was adjusted to 15 ° C., and 0.1 mol of triethylaluminum / n-heptane solution (10 wt%) was added as Al (C ₂ H ₅ ) ₃ . Thereafter, prepolymerization was performed by supplying propylene at a rate of 50 g / hour for 2 hours. After completion of the prepolymerization, the residual monomer was purged and the solid catalyst was thoroughly washed with n-heptane. After the washing, drying under reduced pressure was performed to obtain a prepolymerized catalyst. The prepolymerized catalyst contained 2.0 g of polypropylene per 1 g of the catalyst.
(Iii) Polymerization Production Example except that the prepolymerized catalyst thus obtained was used, and triethylaluminum was continuously fed at 10 g / hour instead of triisobutylaluminum, and the polymerization conditions shown in Table 3 were used. In the same manner as in No. 5, a propylene-ethylene block copolymer was produced.
From the obtained polymer powder, raw material pellets (PEB-6) were obtained by the same additive formulation and granulation conditions as in Production Example 1.

(Production Example 7)
In Production Example 1, polymerization was carried out in the same manner as in Polymerization Production Example 1 except that only the first step was carried out without carrying out the second step, and a propylene-ethylene random copolymer was produced.
From the resulting propylene-ethylene random copolymer powder, raw material pellets (PEB-7) were obtained under the same additive formulation and granulation conditions as in Production Example 1.
Table 3 shows the polymerization conditions and polymerization results, and Table 4 shows the characteristics of the pellets PEB-1 to PEB-7.

(2) Adhesive layer resin As the soft propylene-based resin for the adhesive layer, VISTAMAXX 1100 (soft PP-1) manufactured by ExxonMobil Chemical, VISTAMAXX 1120 (soft PP-2) manufactured by ExxonMobil Chemical, manufactured by Dow Chemical VERSIFY PPDE3300 (soft PP-3) was used. These physical properties are shown in Table 5.

(3) Release treatment layer As the release treatment layer, as a silicone release agent, X-62-2378 (manufactured by Shin-Etsu Chemical Co., Ltd.), polydimethylsiloxane SH200 (manufactured by Dow Corning Toray), three-dimensional organopoly X-92-140 (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as siloxane, and Pyroyl 1010 (manufactured by Yushi Co., Ltd.) was used as a long-chain alkyl release agent.

Example 1
PEB-1 as the base material layer, soft PP-1 as the adhesive layer, and toluene solution (solid content 30) of X-6-2378 (manufactured by Shin-Etsu Chemical Co., Ltd.) as an addition type silicone release agent as the release treatment layer. %) In a toluene / xylene solution (solid content 30%) of X-92-140 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a three-dimensional organopolysiloxane so that the three-dimensional organopolysiloxane content is 30%. A mixed solution was used.
Extruder 35 mmφ for substrate layer, 20 mmφ for adhesive layer, multilayer T-die molding machine with air knife and cooling roll, forming temperature 230 ° C, cooling roll temperature 30 ° C, substrate layer thickness 40 µm A co-pressed two-layer film composed of a two-layer T-die film having an adhesive layer thickness of 10 μm was prepared. On the other side of the adhesive layer of the base material layer of the obtained multilayer film, 3 in a toluene solution (solid content 30%) of X-62-2378 (manufactured by Shin-Etsu Chemical Co., Ltd.) as an addition type silicone release agent. A solution obtained by mixing a toluene / xylene solution (solid content 30%) of X-92-140 (manufactured by Shin-Etsu Chemical Co., Ltd.) as a three-dimensional organopolysiloxane so that the three-dimensional organopolysiloxane content is 30%. after applying such a 0.38 g / m ^2, to prepare a surface protective film forming the release treatment layer is heat treated 120 ° C. × 1 min. Table 6 shows the evaluation results of the obtained surface protective film.

(Example 2)
A film was formed and evaluated in the same manner as in Example 1 except that the base layer resin PEB-1 used in Example 1 was replaced with PEB-2. The results are shown in Table 6.

(Example 3)
Evaluation was performed by forming a film by the same method as in Example 1 except that the adhesive layer resin soft PP-1 used in Example 1 was replaced with PP-2. The results are shown in Table 6.

(Example 4)
Except that the release treatment agent used in Example 1 was replaced with a layer formed by applying a 2% toluene solution of Pyroyl 1010 (manufactured by Yushi Co., Ltd.) as a long-chain alkyl release treatment agent and then treating it. The film was formed by the same method as in Example 1 and evaluated. In addition, the processing method apply | coated 2% toluene solution of Pyroyl 1010 (made on the other hand company oil and fat Co., Ltd.) so that it might become 0.02 g / m < ² >, and heat-processed at 80 degreeC x 1 minute, and formed the peeling process layer. The results are shown in Table 6.

(Example 5)
PEB-1 as a base material layer, soft PP-1 as an adhesive layer, 99.75% by weight of a propylene resin WFX4 polymerized using a metallocene catalyst as a release treatment layer, and polydimethylsiloxane as a silicone release agent A 0.25 wt% melt-extruded mixed composition of SH200 (manufactured by Toray Dow Corning Co., Ltd.) was used.
Extrusion treatment layer thickness of 10 μm and substrate layer thickness of 30 μm at a molding temperature of 230 ° C. using a three-layer T-die molding machine having a substrate layer extruder of 35 mmφ, an adhesive layer extruder of 20 mmφ, and a release treatment layer extruder of 20 mmφ A surface protective film made of a co-pressed three-layer T-die film having an adhesive layer thickness of 10 μm was prepared. Table 6 shows the evaluation results of the obtained surface protective film.

(Comparative Example 1)
A film was formed and evaluated in the same manner as in Example 1 except that the base layer resin PEB-1 used in Example 1 was replaced with PEB-3. The results are shown in Table 7.

(Comparative Example 2)
A film was formed and evaluated in the same manner as in Example 1 except that the base layer resin PEB-1 used in Example 1 was replaced with PEB-4. The results are shown in Table 7.

(Comparative Example 3)
A film was formed and evaluated in the same manner as in Example 1 except that the base layer resin PEB-1 used in Example 1 was replaced with PEB-5. The results are shown in Table 7.

(Comparative Example 4)
A film was formed and evaluated in the same manner as in Example 1 except that the base layer resin PEB-1 used in Example 1 was replaced with PEB-6. The results are shown in Table 7.

(Comparative Example 5)
A film was formed and evaluated in the same manner as in Example 1 except that the base layer resin PEB-1 used in Example 1 was replaced with PEB-7. The results are shown in Table 7.

(Comparative Example 6)
A film was formed and evaluated in the same manner as in Example 1 except that the adhesive layer resin soft PP-1 used in Example 1 was replaced with soft PP-3. The results are shown in Table 7.

From the results of Tables 6 and 7, the surface protective film of the present invention has no sticky component bleed, so it does not affect the adherence to the adherend, and does not affect the peelability between the outer layer and the adhesive layer. It turns out that there are few eyes (Examples 1-5).
On the other hand, the propylene-ethylene block copolymer in which Mw / Mn obtained by the Ziegler catalyst is outside the scope of the present invention has too many fish eyes (Comparative Example 4). On the other hand, if the MFR is higher than the range of the propylene-ethylene block copolymer of the present invention, draw resonance occurs during molding, and a film having an unstable thickness and a uniform thickness cannot be obtained (Comparative Example 2). On the other hand, if the MFR is too low, a shark skin (rough skin) is generated on the film surface, and a film having a good appearance cannot be formed (Comparative Example 3). In addition, if the amount of the component (A2) is too large, bleeding due to the sticky component is remarkable, and this affects the contamination of the adherend and the peelability between the outer layer and the adhesive layer. . Moreover, the film using the propylene-ethylene random copolymer which does not contain the component (A2) for the base material layer has higher rigidity and flexibility than the film using the propylene-ethylene block copolymer of the present invention for the base material layer. Is inferior (Comparative Example 5). Moreover, when S- ₁₅ is less than the range of the soft polypropylene resin of the present invention, sufficient adhesion cannot be obtained (Comparative Example 6).

  The surface protective film of the present invention uses a specific propylene-ethylene block copolymer as a base material layer, a specific soft polypropylene resin as an adhesive layer, and a silicone or long-chain alkyl release agent as a release treatment. Because it is used for the layer, there are very few unmelted fish eyes at the time of film forming, and even if the surface protection film is stuck on the object to be stacked and stored, the object to be protected does not dent and is transparent Excellent resistance to contamination on the adherend. Furthermore, since a silicone-based or long-chain alkyl-based release treatment agent is used for the release treatment layer, when the roll is unwound from the roll winding state where both the adhesive layer and the release treatment layer are in contact with each other in a solid state, it is used. Sometimes it can be used as a surface protective film having the property of improving the feeding performance, and for protecting the surface of building members such as synthetic resin plates, decorative plates, metal plates, glass plates, and liquid crystals such as polarizing plates and retardation plates. It can be suitably used as a film for protecting the surface of the constituent member of the display.

Claims (5)

In the surface protective film in which the adhesive layer is formed on one surface of the base material layer and the release treatment layer is formed on the other surface, the base material layer is polymerized using a metallocene catalyst, and the following (a1) to (a3) , (A5), (a8) and a soft polypropylene resin (A) formed of a propylene-ethylene block copolymer (A) having the characteristics (a9) and having an adhesive layer having the following characteristics (b1) to (b4) ( A film for surface protection, which is formed in B), and the release treatment layer is formed of a silicone-based or long-chain alkyl-based release treatment agent (C).
(A) Propylene-ethylene block copolymer (a1) 30-95 propylene-ethylene random copolymer component (A1) having an ethylene content of 0.5-6 wt% in the first step using a metallocene catalyst. Propylene-ethylene obtained by sequential polymerization of 70 to 5 wt% of propylene-ethylene random copolymer component (A2) containing 6 to 20 wt% more ethylene than component (A1) in the second step. Block copolymer (a2) Melt flow rate (MFR: 230 ° C. 2.16 kg) is 1 to 30 g / 10 min
(A3) The component amount W having a molecular weight of 5,000 or less obtained by gel permeation chromatography (GPC) is 0.8% by weight or less of the whole.
(A5) TREF elution curve obtained as a plot of elution amount (dWt% / dT) against temperature by the temperature rising elution fractionation method (TREF) in the temperature range of −15 ° C. to + 140 ° C. using an o-dichlorobenzene solvent In
The peak temperature T (A1) observed on the high temperature side is in the range of 55 ° C. to 96 ° C.,
The peak temperature T (A2) observed on the low temperature side is 45 ° C. or lower, or the peak temperature T (A2) is not observed,
The temperature T (A4) at which 99% by weight of the propylene-ethylene block copolymer elutes is 98 ° C. or lower.
(A8) Intrinsic viscosity [η] cxs measured in a 135 ° C. decalin for 23 ° C. xylene solubles is 1 to 2 dl / g
(A9) In the temperature-loss tangent (tan δ) curve obtained by solid viscoelasticity measurement (DMA), the tan δ curve has a single peak at 0 ° C. or less. (B) Soft propylene resin (b1) Melt flow rate ( MFR: 230 ° C., 2.16 kg) is 2 to 30 g / 10 minutes (b2) Density is 0.85 to 0.89 g / cm ³
(B3) The ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) determined by gel permeation chromatography (GPC) is 1.5-3.
(B4) Soluble content (S- ₁₅ ) of -15 [deg.] C. or lower measured by temperature rising elution fractionation (TREF) method is 55% by weight or more The film for surface protection according to claim 1, wherein the propylene-ethylene block copolymer (A) further satisfies the following property (a4).
(A4) In the component (A1) obtained in the first step, the proportion of the entire propylene-ethylene block copolymer is in the range of 30 to 85% by weight,
In the component (A2) obtained in the second step, the proportion of the entire propylene-ethylene block copolymer is in the range of 70 to 15% by weight. The film for surface protection according to claim 1 or 2 , wherein the propylene-ethylene block copolymer (A) satisfies the following properties (a6) to (a7).
(A6) The component (A1) obtained in the first step is a propylene-ethylene random copolymer having an ethylene content of 1.5 to 6% by weight, and the proportion of the propylene-ethylene block copolymer is 30 to 70% by weight. % Range,
The component (A2) obtained in the second step has an ethylene content that is 8 to 15% by weight higher than that of the component (A1), and the proportion of the entire propylene-ethylene block copolymer is in the range of 70 to 30% by weight. (A7) TREF elution curve obtained as a plot of elution amount (dWt% / dT) against temperature by the temperature rising elution fractionation method (TREF) in the temperature range of −15 ° C. to + 140 ° C. using an o-dichlorobenzene solvent In
The peak temperature T (A1) observed on the high temperature side is in the range of 60 ° C. to 88 ° C.,
The peak temperature T (A2) observed on the low temperature side is 40 ° C. or lower, or the peak temperature T (A2) is not observed,
The temperature T (A4) at which 99% by weight of the propylene-ethylene block copolymer elutes is 90 ° C. or lower. It is used for the surface protection of a building member, The film for surface protection of any one of Claims 1-3 characterized by the above-mentioned. It is used for the surface protection of a liquid crystal display device structural member, The film for surface protection of any one of Claims 1-3 characterized by the above-mentioned.

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