JP2003342394A - Polyester soft film for protective film - Google Patents

Abstract

(57) [Problem] To provide a protective film made of a polyester film exhibiting the same strength and elongation as a vinyl chloride film, which has conventionally been considered difficult, particularly a protective film for a dry film. A dicarboxylic acid component (A) in which at least 50 mol% is terephthalic acid or naphthalenedicarboxylic acid and a diol component (B) in which at least 50 mol% is ethylene glycol, and further a copolymerization component or a blend component Or a single layer of a polyester resin containing a polyalkylene ether glycol component (C) at a ratio of 10% by weight or more and 50% by weight or less based on the total amount of the components (A) to (C). And a Young's modulus (E) in at least one direction of the film is 0.1 to 2.
0 (GPa) and elongation (S) are 150 to 400 (%).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester soft film for a protective film, and more particularly to a polyester soft film mainly used as a protective film for dry film applications.

[0002]

Protective films are used in various industrial applications. For example, a protective film for LCD (liquid crystal) is typical, but a protective film for a dry film is particularly important among them. Since the protective film for dry film does not contain its softness and plasticizer,
Currently, polyolefin films are used. However, in the case of a polyolefin film, it is difficult to remove foreign substances mixed in the film, and therefore, a polyester soft film in which foreign substances are easily removed with a filter or the like has been demanded.

[0003]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a protective film made of a polyester film showing strength and elongation comparable to that of a vinyl chloride film, which has been considered difficult in the past, especially a protective film for use in a dry film. It is in.

[0004]

Means for Solving the Problems As a result of extensive studies, the present inventor has found that a polyester film in which a specific component is combined can easily achieve the above object, Came to completion.

That is, the gist of the present invention is that it is formed from a dicarboxylic acid component (A) in which 50 mol% or more is terephthalic acid or naphthalene dicarboxylic acid and a diol component (B) in which 50 mol% or more is ethylene glycol. Contains a polyalkylene ether glycol component (C) as a copolymer component or a blend component, and its ratio is 10% by weight as a value relative to the total amount of the components (A) to (C).
% Or more and 50% by weight or less of a single layer of a polyester resin or a multi-layered film containing at least one single layer, the Young's modulus (E) (GPa) and elongation (S) in at least one direction of the film. ) (%) Satisfy the following formulas (i) and (ii), respectively, in the polyester soft film for a protective film.

[0006]

[Equation 2] 0.1 <E <2.0 (i) 150 <S <400 (ii)

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
The polyester soft film for a protective film of the present invention comprises a single layer made of a specific polyester resin or a multilayer film containing at least one single layer.

The above polyester resin is formed from a dicarboxylic acid component (A) in which 50 mol% or more is terephthalic acid or naphthalene dicarboxylic acid and a diol component (B) in which 50 mol% or more is ethylene glycol, and further, A polyalkylene ether glycol component (C) is contained as a polymerization component or a blend component.

That is, in the polyester resin used in the present invention, it is important that the polyalkylene ether glycol component (C) is contained in a high concentration described later, and it may be in any form of a copolymerization component or a blending component. It may be contained. In a preferred embodiment of the present invention, a copolyester containing the polyalkylene ether glycol component (C) in the form of a copolymer component is preferred. Therefore, the following description will be based mainly on the copolyester.

Examples of the dicarboxylic acid component (A) include terephthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid,
Azelaic acid, sebacic acid, phthalic acid, isophthalic acid,
One or more kinds of naphthalene dicarboxylic acid, diphenyl ether dicarboxylic acid and the like can be mentioned. In the present invention, 50 mol% or more of the component (A) is terephthalic acid or naphthalene dicarboxylic acid, but terephthalic acid is preferable.

Examples of the diol component (B) include ethylene glycol, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, ethylene glycol, polyalkylene glycol, 1.4-cyclohexanedimethanol and neopentyl glycol. One or more aliphatic diols and / or alicyclic diols may be mentioned. In the present invention, 50 mol% or more of the component (B) is ethylene glycol.

In the present invention, in the polyester resin, as long as it does not impair the effects of the present invention,
For example, 4,4'-dihydroxybiphenol, 2,2
-Bis (4'-hydroxyphenyl) propane, 2,2
-Aromatic diols such as bis (4'-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, glycolic acid, p-hydroxybenzoic acid, Hydroxylcarboxylic acids such as p-β-hydroxyethoxybenzoic acid, alkoxycarboxylic acids, stearic acid, stearyl alcohol, benzyl alcohol, benzoic acid, t-butylbenzoic acid, monofunctional components such as benzoylbenzoic acid, tricarballylic acid, hexane Tricarboxylic acid, trimellitic acid, trimesic acid, pyromellitic acid, benzophenonetetracarboxylic acid, naphthalenetetracarboxylic acid, 1,2,6-hexanetriol, gallic acid,
A trifunctional or higher polyfunctional component such as trimethylolethane, trimethylolpropane, glycerol, pentaerythritol, sorbitol, dipentaerythritol, and polyglycerol may be contained.

The polyalkylene ether glycol component (C) is, for example, polyethylene glycol, polypropylene glycol, polytrimethylene ether glycol, polytetramethylene ether glycol, polyhexamethylene ether glycol, a block or random of ethylene oxide and propylene oxide. Examples thereof include copolymers. These can also be used in combination of two or more kinds. Among these, polyethylene glycol and polytetramethylene ether glycol are preferable, and polytetramethylene ether glycol is particularly preferable.

The number average molecular weight of the polyalkylene ether glycol component (C) is usually 300 to 10,000.
0, preferably 400 to 3000, more preferably 5
It is 00 to 1500. If the number average molecular weight is less than 300, the heat resistance of the film may be poor, or a low molecular weight substance may be deposited. If it exceeds 100,000, the transparency of the film may be poor. When a plurality of polyalkylene ether glycol components (C) having different molecular weights are used in combination, the average value of the number average molecular weight may be within the above range. The number average molecular weight can be measured by a general method such as gel permeation chromatography.

The polyalkylene ether glycol component (C) is contained in the polyester resin in an amount of 10% by weight or more and 50% by weight or more.
Weight% or less (value relative to the total amount of components (A) to (C))
Must be included. When the content of the polyalkylene ether glycol component (C) is less than 10% by weight, the flexibility of the film is poor, and when it exceeds 50% by weight, it is difficult to form a film. The content of the polyalkylene ether glycol component (C) is preferably 15% by weight.
40% by weight or more and more preferably 20% by weight or more 3
It is 5% by weight or less.

In the multilayer film containing at least one single layer made of the polyester resin, the layers other than the single layer are mainly made of polyester made of dicarboxylic acid and diol. Typical polyesters include polyethylene terephthalate (PET) and its copolymer, polyethylene-2,6-naphthalene dicarboxylate (PFH) and its copolymer, polycyclohexane dimethylene terephthalate and its copolymer (PCT).
Etc. are exemplified, but from the viewpoint of cost-performance, polyester containing 95 mol% or more of PET is preferable.

Each of the above-mentioned polyester resins constituting each layer of the present invention is produced batchwise or continuously according to a conventional production method of polyester resin (direct polymerization method, transesterification method, etc.). The polyalkylene ether glycol component (C) and optional components other than terephthalic acid and ethylene glycol can be added at any stage of the polycondensation reaction process.

In addition, the above polyester resin is
It can also be obtained by producing an oligomer having a low degree of polymerization, which comprises a dicarboxylic acid component (A) and a diol component (B), and polycondensing the oligomer with the polyalkylene ether glycol component (C).

The resin obtained by the polycondensation reaction is usually
It is withdrawn in a strand form from an outlet provided at the bottom of the polycondensation reaction tank, and is cut with a cutter into pellets while cooling with water or after water cooling. Furthermore, by subjecting the pellets after this polycondensation to a solid phase polycondensation by heat treatment, it is possible to further increase the degree of polymerization and to reduce acetaldehyde, low molecular weight oligomers and the like as reaction by-products.

In the above-mentioned production method, the esterification reaction may be carried out, if necessary, in the presence of, for example, diantimony trioxide, an ester salt of an organic acid salt of antimony, titanium, magnesium, calcium or the like, or an organic metal compound. You can do it below. The transesterification reaction can be carried out, if necessary, in the presence of an ester exchange catalyst such as an organic acid salt of lithium, sodium, potassium, magnesium, calcium, manganese, titanium, zinc or an organic metal compound. .

The polycondensation reaction is carried out, for example, in the presence of phosphorus compounds such as orthophosphoric acid, phosphorous acid, hypophosphorous acid, polyphosphoric acid, their esters and organic acid salts, and, for example, diantimony trioxide, dioxide. Metal oxides such as germanium and germanium tetroxide, or antimony, germanium,
It can be carried out in the presence of a polycondensation catalyst such as an organic acid salt of zinc, titanium, cobalt or the like or an organic metal compound. Particularly, as the polycondensation catalyst, one or more selected from tetrabutoxy titanate, antimony trioxide, and germanium dioxide are preferably used. Furthermore, in order to promote defoaming in the polycondensation process, it is preferable to add a defoaming agent such as silicone oil.

The copolymerized polyester containing the polyalkylene ether glycol component (C) in the form of a copolymer component has been described above. The polyalkylene ether glycol component (C) is contained in the form of a blend component. Blending of the polyalkylene ether glycol component (C) in the case of polyester can be carried out by a method of melt-kneading using a melt extruder.

The intrinsic viscosity of the above polyester resin (value measured at 30 ° C. in a mixed solvent of phenol / 1,1,2,2-tetrachloroethane (weight ratio = 1/1)) is usually 0.4 or more and 1 or more. 0.5 dl / g or less, preferably 0.5 or more and 1.2 dl / g or less, more preferably 0.6 or more and 1.0 or more
It is dl / g or less. When the intrinsic viscosity is less than 0.4 dl / g, the strength of the film is poor, and when it exceeds 1.5 dl / g, it becomes difficult to form the film.

The polyester resin forming the surface layer preferably contains inorganic or organic particles in order to impart blocking resistance, slipperiness and the like when it is formed into a stretched film. Examples of the inorganic particles include silica, alumina, titania, kaolin, clay, calcium carbonate, calcium phosphate, calcium fluoride, carbon black, as well as alkali metal, alkaline earth metal, and phosphorus compound catalysts during polyester polymerization. And the like. Further, examples of the organic particles include various crosslinked polymers and the like.

The average particle size of the particles is usually 0.001 or more and 10 μm or less, preferably 0.005 or more and 4 μm, and more preferably 0.01 or more and 3 μm or less. The average particle size of particles is measured by an electromagnetic wave scattering method such as a laser diffraction method or a dynamic light scattering method, or a light transmission method such as a centrifugal sedimentation method. The average particle diameter is the 50% volume average particle diameter (d50) measured by the above method.

The particles are usually added during the polycondensation process of the resin, but particles other than the precipitates caused by the catalyst may be added during the resin molding process. The content of particles is usually 0.005 or more and 10% by weight or less, preferably 0.01 or more and 1.0% by weight or less, and more preferably 0.02 or more and 0.5% by weight or less with respect to the film.

The polyester resin of the present invention may contain various additives as long as the effects of the present invention are not impaired.

Examples of the above additives include polyethylene, polypropylene, maleic anhydride modified products thereof, polyolefin resins such as ionomers, polyamide resins,
Other thermoplastic resins such as polycarbonate resins and polystyrene resins and thermoplastic elastomers, as well as polyalkylene ether glycols which are not copolymerized with polyester resins, may be mentioned.

Further, as the above-mentioned additives, antioxidants such as hindered phenols, phosphites and thioethers, benzotriazoles, benzophenones, benzoates, hindered amines, cyanoacrylates, etc. Agents, inorganic and organic crystal nucleating agents, molecular weight modifiers, hydrolysis resistant agents, antistatic agents, lubricants, mold release agents, plasticizers, flame retardants, flame retardant aids, foaming agents, colorants, dispersion aids Examples include additives such as agents, and reinforcing materials such as glass fiber, carbon fiber, mica, and potassium titanate fiber.

The above-mentioned additives may be added during the polycondensation process of the resin, but may be added during the molding process of the resin.

The film of the present invention is characterized in that Young's modulus (E) (GPa) and elongation (S) (%) in at least one direction satisfy the following equations (i) and (ii), respectively. .

[0032]

[Equation 3] 0.1 <E <2.0 (i) 150 <S <400 (ii)

The Young's modulus (E) is preferably 0.
It is 3 Gpa or more and 1.8 Gpa or less. Young's modulus (E)
Of less than 0.1 Gpa makes it difficult to form the film, and more than 2.0 Gpa results in poor flexibility of the film.

The above elongation (S) is preferably 160%.
Or more and 350% or less, more preferably 170% or more and 300
% Or less. Further, the elongation (S) in all directions of the film is preferably within the above range. Elongation (S)
Is less than 150%, the flexibility of the film is inferior and 4
If it exceeds 00%, it is too soft and the function as a film is impaired.

The thickness of the film of the present invention is not particularly limited, but is usually 1.0 μm or more and 500 μm or less. The heat shrinkage rate of the film of the present invention after treatment at 100 ° C. for 30 minutes is preferably 10.0% or less. In addition, in the multilayer film including at least one single layer made of the polyester resin, two layers other than the above single layer are usually provided as layers forming the surface layer. In this case, the ratio of the thickness of each of the both side layers to the thickness of the inner layer (the layer made of the polyester resin) is usually 1: 0.01.
Is 0.5 to 0.5, preferably 0.05 to 0.5.

Next, the method for producing the film of the present invention will be described. In the case of a single-layer film made of polyester resin, first, the raw material chips are dried if necessary, and then
Melt at a temperature of 200-300 ° C. using an extruder,
After extrusion, it is rapidly cooled on a casting drum to obtain an unstretched sheet. A hopper dryer, a paddle dryer, a vacuum dryer or the like can be used to dry the polyester chips, but without performing such drying, TE
It is preferable to use an extruder with a vent such as X. The T-die method is suitable for extrusion. Further, in casting, a so-called electrostatic contact method is used to obtain a sheet having a small thickness unevenness.

Then, the obtained unstretched sheet is heated to (Tgmin-10 ° C) or more (Tcmax) in the subsequent stretching step.
Stretching is performed 2.0 times or more in the longitudinal direction and / or the transverse direction in a temperature range of −5 ° C. or less. Here, "Tgmin"
Is the minimum Tg of the raw material polyester, "Tcmax"
Represents the maximum value of Tc of the raw material polyester. However, T
For polyesters that do not show g, the value obtained by extrapolating the value at the crystalline content is used.

The uniaxially or biaxially stretched film thus obtained is then subjected to a heat setting step of 150 to 240 ° C.
Heat fix at the temperature of. The heat setting is generally performed under a tension setting, but at the time of heat setting and / or cooling after the heat setting, the film is stretched in the longitudinal direction and / or the width direction of the film.
% Or less can be relaxed or the width can be extended.

Further, during or after the stretching process, one or both surfaces of the film may be subjected to various surface treatments such as corona discharge treatment, chemical solution treatment and flame treatment to improve the adhesiveness of the film. Furthermore, it is possible to improve the adhesiveness, antistatic property, slipperiness and the like of the film by applying to one side or both sides of the film during the stretching step or before or after the stretching.

In the case of a multilayer film containing at least one single layer made of a polyester resin, it is produced by the same method as described above except that a coextrusion method (coextrusion method) is adopted for extrusion.

The single-layer or multi-layer polyester soft film obtained as described above is wound up and used as a protective film. Further, since it has less thickness deviation and less adhesion and inclusion of foreign matter and dust, it is suitably used for various protective films, especially for protective films for dry films.

[0042]

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. The evaluation method and the method for producing the raw material polyester are as follows. Moreover, "part" means "part by weight".

(1) Intrinsic viscosity [η]: 1 g of polymer is phenol / tetrachloroethane = 50/50 (weight ratio)
Dissolve in 100 ml of mixed solvent of and measure at 30 ° C.

(2) Young's Modulus (E): Length 30 adjusted to a temperature of 23 ° C. and a humidity of 50% RH using a “tensile tester Intesco model 2001 type” manufactured by Intesco Co., Ltd.
A sample film having a width of 0 mm and a width of 20 mm was stretched at a strain rate of 10% / min and calculated by the following equation (iii) using the first linear portion of the tensile stress-strain curve.

[0045]

[Equation 4] E = (Δσ / Δε) × 9.807 (iii) E: Young's modulus (tensile modulus) (MPa) Δσ: Stress difference due to the original average cross-sectional area between two points on the straight line Δε: Strain difference between the same two points

(3) Elongation (S): "Tensile testing machine Intesco model 2001 type" manufactured by Intesco Co., Ltd. was used.
50mm length adjusted to temperature 23 ℃ and humidity 50% RH
A sample film having a width of 15 mm was pulled at a speed of 200 mm / min, and the value shown in the following equation (iv) was obtained from the tensile stress-strain curve.

[0047]

[Equation 5] S = (L-L.) / L. × 100 ・ ・ ・ (iv) S: Elongation (tensile fracture elongation) (%) L: Gauge distance at break (mm) L. : Original gauge length (mm)

(4) Melting point (Tm), second-order transition temperature (T
g), crystallization temperature (Tc): From 10 mg of the sample piece, "MDSC29" manufactured by TA Instruments Co., Ltd.
20 "was used for the measurement. Melting point is (Tm)
Was heated at a rate of 20 ° C./min in the range of 20 to 300 ° C., and the peak temperature of the melting endothermic peak was taken as the melting point (Tm).
The second-order transition temperature (Tg) is 20 ° C / mi between 20 and 290 ° C.
Glass transition when the temperature was raised at a rate of n, melted and held at 290 ° C. for 3 minutes, then rapidly cooled at a temperature of 20 ° C. or lower, and then again raised at a rate of 20 ° C./min in the range of 20 to 200 ° C. The displacement temperature due to was defined as the second-order transition temperature (Tg). Furthermore,
Crystallization temperature (Tc) 20 to 290 ℃ 20 ℃ / min
The temperature was raised at a rate of, and the mixture was melted and held at 290 ° C. for 3 minutes,
The peak temperature of the crystallization peak when the material was rapidly cooled to 20 ° C or lower and then heated again in the range of 20 to 200 ° C at a rate of 20 ° C / min was defined as the crystallization temperature (Tc).

Example 1 30.3 kg of terephthalic acid, ethylene glycol 12.
2 L, polytetramethylene ether glycol (number average molecular weight 1000) 15.0 kg as a raw material, tetrabutoxy titanate, orthophosphoric acid and cobalt acetate as catalysts and co-catalysts, and amorphous silica with an average particle diameter of 2.4 μm ( Fuji Silysia "Silysia 320") was added to the polyester in an amount of 0.15 wt.
A copolyester resin was obtained by the direct polycondensation method at 70 ° C. and 400 Pa. Then, the copolyester resin was extracted from the polymerization tank in a strand form, cooled, and then cut with a pelletizer to be recovered in a pellet form. The intrinsic viscosity of the obtained copolyester resin chip was 0.79.

The above chips were air-dried, supplied to a vented twin-screw extruder (TEX), extruded at 255 ° C., and rapidly cooled on a casting drum to obtain an unstretched resin sheet.
The unstretched resin sheet thus obtained was subjected to 5 by a roll stretching machine.
After stretching 3.5 times in the longitudinal direction at 0 ° C., it was stretched 3.6 times in the transverse direction at 70 ° C. by a tenter stretching machine, and subsequently heat set at 200 ° C. in a tenter and biaxially stretched to 25 μm. I got a film.

The Young's modulus (E) and the elongation (S) of the obtained film were measured.
The film was highly flexible with 5 Gpa and 300%. When compared with a film of polyethylene terephthalate simple substance obtained by a conventional method (Comparative Example 1), Young's modulus is 1/10 and elongation is about 2.3 times, which is a flexible polyester film that has never been seen. There was found. Then, when an adhesive or the like was applied to this film as a base and actually used as a protective film for a dry film, excellent results were obtained with excellent accuracy in thickness of the film and less contamination and adhesion of foreign matter.

Example 2 34.6 kg of terephthalic acid, ethylene glycol 14.
0 L, polytetramethylene ether glycol (number average molecular weight 1000) 10.0 kg as a raw material, tetrabutoxy titanate, orthophosphoric acid and cobalt acetate as catalysts and co-catalysts, and by direct polycondensation method at 270 ° C. and 400 Pa. Copolyester resin (CO-PE
T) was obtained. Then, CO-PET was extracted in a strand form from the polymerization tank, cooled, and then cut with a pelletizer to collect in a pellet form.

On the other hand, the average particle size of polyester is 2.
A polyethylene terephthalate resin (H) was added in accordance with a conventional method except that 4 μm of amorphous silica (“Sylysia 320” manufactured by Fuji Silysia Chemical Ltd.) was added so as to be 0.15 wt%.
M-PET) was obtained.

The above-mentioned CO-PET and HM-PET pellets were air-dried and dried, respectively, and fed to a vented twin-screw extruder (TEX) through separate conduits.
-PET was extruded at 255 ° C and HM-PET was extruded at 300 ° C to obtain an unstretched laminated film of HM-PET / CO-PET / HM-PET with 2 layers and 3 layers.

The unstretched resin sheet was stretched 3.5 times in the machine direction at 50 ° C. by a roll stretching machine, and then stretched 3.6 times in the transverse direction at 70 ° C. by a tenter stretching machine, and subsequently in a tenter. Heat set at 200 ° C at 25 μm 2
An axially stretched film was obtained (the film thickness constitution was 2 μm /
21 μm / 2 μm).

The Young's modulus (E) and elongation (S) of the obtained laminated film were measured and found to be 1.8 Gpa.
And a film having a high flexibility of 170%. In addition, the foreign matter, which is a problem with polyolefin, was an overwhelmingly small film. When this film was used as a protective film for a dry film by applying an adhesive or the like to the base, the film was excellent in thickness accuracy and foreign matter was not mixed or adhered, and good results were obtained.

[0057]

Industrial Applicability According to the present invention described above, there is provided a protective film made of a polyester film, which has been considered to be difficult in the past, and exhibits strength and elongation comparable to those of vinyl chloride films, especially for dry films.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4F071 AA44 AA51 AF14 AF21 AH12                       BA01 BB06 BB08 BC01                 4F100 AA20 AK41A AL01A AL05A                       AT00B BA02 EH17 EH172                       EJ38 EJ382 EJ50 EJ502                       GB90 JK13A                 4J002 CF051 CF081 CF101 CH022                       GQ00

Claims (4)

[Claims] 1. A dicarboxylic acid component (A) containing 50 mol% or more of terephthalic acid or naphthalenedicarboxylic acid and a diol component (B) containing 50 mol% or more of ethylene glycol. A single layer composed of a polyester resin containing a polyalkylene ether glycol component (C) as a component and having a ratio of 10% by weight or more and 50% by weight or less based on the total amount of the components (A) to (C), or the single layer. A multi-layered film including at least one layer, wherein Young's modulus (E) (GPa) and elongation (S) (%) in at least one direction of the film are the following formulas (i) and (ii), respectively.
A polyester soft film for a protective film, which satisfies the formula. [Equation 1] 0.1 <E <2.0 (i) 150 <S <400 (ii) 2. The polyester-based soft film for a protective film according to claim 1, wherein the polyalkylene ether glycol component (C) is contained as a copolymerization component. 3. The polyester soft film for a protective film according to claim 1, wherein the polyalkylene ether glycol component (C) is polytetramethylene ether glycol having a number average molecular weight of 300 to 100,000. 4. The polyester soft film for a protective film according to claim 1, wherein the protective film is a dry film protective film.