JPH10272747A - Laminated stretch shrink film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently heat seal a various tray shapes by mixing specific wt.% of nonionic surfactant composition in one or more layers, and orienting it. SOLUTION: A laminated film having a surface layer of a mixture obtained by mixing polyethylene resin (A) such as low-density polyethylene and low crystalline ethylene-α-olefin copolymer (B) having a density of 0.860 to 0.900 g/cm<3> and a melt index of 0.1 to 20 g/10 min at a melt peak temperature of 50 to 100 deg.C by amorphous or differential scanning calorimeter by weight indicated by a formula of 0<=(B)/A+B)<=0.7 and a core layer containing as a main component a mixture obtained by mixing polypropylene flexible resin (C) of a mixture of 5 to 50 wt.% of atactic polypropylene and 50 to 95 wt.% of crystalline isoatactic polypropylene and polybutene-1 (D) by weight indicated by a formula of 0.10<=(C)/(D)<=9.0 is obtained. This one or more layers is mixed with 0.1 to 4.0 wt.% of nonionic surfactant composition, and laterally and longitudinally oriented by twice or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated stretch shrink film, and more particularly, to a heat-sealing film for stretch packaging or shrink packaging mainly used for pre-packaging of retail goods, mainly for food products. Excellent suitability for automatic wrapping machines such as stretchability and film trim, etc. (hereinafter referred to as collected products)
The present invention relates to a laminated stretch shrink film having at least three or more layers having good transparency and gloss even when recycled.

[0002]

2. Description of the Related Art In recent years, demand for stretch films for packaging foods such as meat, seafood, vegetables, fruits, and prepared foods has been further increasing with the expansion of supermarkets and convenience stores. Conventionally, the stretch film is most frequently used because a film made of plasticized polyvinyl chloride has excellent performance in transparency and self-adhesion, but using a large amount of a plasticizer. Therefore, the amount of water vapor permeated increases, and the packaged product is likely to be lost or deteriorated, the plasticizer easily migrates to the packaged product and becomes contaminated, or when the film is blown during molding or packaging. In addition, there is a problem of safety and health and pollution such as generation of harmful hydrogen chloride gas at the time of waste incineration. For this reason, films that can replace plasticized polyvinyl chloride are being actively developed using ethylene resins such as polyethylene and ethylene-vinyl acetate copolymer, polybutadiene resins, and polypropylene resins. However, films obtained from the above-mentioned ethylene-based resin or polypropylene resin have no problem of safety and health and pollution, but are not yet satisfactory as stretch films.

[0003] On the other hand, with the diversification of the packaged items, pickles, tsukudani, etc., which contain a large amount of water, are peeled off due to the adhesion of moisture when the seal is made only by self-adhesiveness, and the packaged items are reduced in weight. Further, there is a problem that the commercial value is reduced, and a material which can be sufficiently heat-sealed is desired. Also, depending on the article to be packaged, wrinkles and tarls may remain due to only stretch properties, and a sufficiently tight packaging finish may not be obtained, and a material having heat shrinkability is desired. In addition, from the viewpoint of increasing productivity and packaging speed, the spread of automatic stretch wrapping machines and stretch shrink automatic wrapping machines in place of hand wrap packaging machines is remarkable in conjunction with the expansion of convenience stores and supermarkets. There is also a strong demand for improved aptitude. The present inventors have already settled on transparency,
Excellent gloss and moderate gas permeability, low water vapor permeability, no loss of packaged material, heat-shrinkability and heat resistance using polyethylene resin without chlorine gas during transfer of plasticizer and combustion For the purpose of providing a film that has stretchability, can be sufficiently heat-sealed by a hot plate, and has a good shrink wrapping finish, a multilayer polyethylene stretch shrink film mainly composed of a specific linear low-density polyethylene is used. Proposed (Japanese Unexamined Patent Publication No. Hei 3-215034,
JP-A-8-90737).

[0004]

However, even with the above-mentioned multilayer polyethylene stretch shrink film, the heat sealability (heating on a hot plate to heat-bond the films) of the automatic packaging machine is not always sufficient. There was also. For example, irregular shaped bottoms, such as raised bottom trays with enhanced display effect and trays with ribs at the bottom for increased strength, have greater temperature unevenness in the heat-sealed part than flat trays. However, even if the temperature of the hot plate is raised to achieve sufficient heat sealing, the film exceeds the heat resistance temperature of the film before the sufficient heat sealing is obtained, and the film is melted and a hole is formed. That is, in order to be able to accommodate trays of various shapes, it is desired to have a heat-sealing temperature range as well as heat resistance, stretchability (flexibility), and transparency.

As a stretch shrink film using a polypropylene resin and a polyethylene resin, for example, JP-A-63-173641, JP-A-8-8
No. 0565, JP-A-6-15027, JP-A-5-318682, JP-A-7-314623 and the like, but these have insufficient stretchability in the lateral direction, Four or more layers achieve a balance of properties, are inferior in heat resistance or transparency, have insufficient heat sealability, decrease the transparency when recycled, or have shrinkage tunnels However, it has one or more drawbacks such as generation of an acetic acid odor after passing through, and it is difficult to say that the film has sufficient properties as a stretch shrink film.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to overcome the drawbacks of the above-mentioned stretch shrink film, and as a result, have found that a core layer mainly composed of a mixture of a specific polypropylene-based soft resin and polybutene-1 is used. By using a surface layer made of polyethylene resin, in a three-layer configuration,
Excellent automatic packaging that can heat-seal enough for trays of various shapes, has stretchability in the horizontal direction, has no odor of acetic acid, and has good transparency and gloss even when recycled products are recycled. The inventor has found that a stretch shrink film having flexibility can be obtained, and the present invention has been completed. That is, the present invention provides a surface layer comprising a mixture of a polyethylene resin of the following (A) and an ethylene-α-olefin copolymer of the following (B) in a weight ratio represented by the following formula (4): A laminated film of three or more layers having a polypropylene-based soft resin and a core layer containing, as a main component, a mixture in which the following polybutene-1 (D) is compounded at a polymerization ratio represented by Formula 5, and at least one layer or more. And a laminated stretch shrink film obtained by blending 0.1 to 4.0% by weight of a non-ionic surfactant composition with each other and subjecting it to a stretching process that is twice or more each in length and width. (A) low density polyethylene, linear low density polyethylene,
At least one or more polyethylene resins selected from ultra-low density polyethylene. (B) an amorphous or differential scanning calorimeter having a density of 0.860 to 0.900 g / cm ³ and a melt index of 0.1 to 20 g / 10 min and a melting peak temperature of 50 to 100;
Low temperature crystalline ethylene-α-olefin copolymer (C) 5 to 50% by weight of atactic polypropylene and 50 to 95% by weight of crystalline isotactic polypropylene
Polypropylene soft resin consisting of a mixture of (D) Polybutene-1

[0007]

## EQU4 ## 0 ≦ (B) / (A + B) ≦ 0.7

[0008]

## EQU5 ## 0.10 ≦ (C) / (D) ≦ 9.0

Hereinafter, the present invention will be described in detail. The polyethylene resin (A) of the surface layer of the present invention mainly has an action of imparting heat sealing properties to a hot plate in an automatic packaging machine. Examples of the polyethylene resin used include low-density polyethylene having a long-chain branch, carbon including ethylene and propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, and decene-1. At least one selected from linear low-density polyethylene and ultra-low-density polyethylene, which is a copolymer with one or two or more α-olefins having 3 to 20, preferably 4 to 8 carbon atoms. No. Of these, linear low-density polyethylene and low-density polyethylene having relatively low density are preferably used from the viewpoint of easily imparting heat-sealing properties at low temperatures, and also provide low-temperature heat-sealing properties by suppressing excessive blocking. From the viewpoint of easiness, a linear low-density polyethylene having a relatively narrow molecular weight distribution and the like produced using a so-called metallocene catalyst (single-site catalyst) is also used.

The density of the polyethylene resin (A) is 0.8
Those having a range of 90 to 0.940 g / cm ³ are preferable,
If it is less than 0.890 g / cm ³ , excessive blocking occurs, which is not preferable. If it exceeds 0.940 g / cm ³ , the low-temperature heat-sealing property is unfavorably reduced. The melt index (hereinafter referred to as MI) is 0.1 to 10 g.
When the amount is less than 0.1 g / 10 minutes, the processability is lowered, which is not preferable. When the amount exceeds 10 g / 10 minutes, excessive blocking occurs.

In the present invention, the ethylene-α-olefin copolymer (B) can be used as a mixture with the above-mentioned polyethylene resin when the low-temperature heat sealing property is required for the surface layer due to packaging conditions and the like. . Examples of the ethylene-α-olefin copolymer to be used include amorphous and low-crystalline ethylene and α having a melting peak temperature of 50 to 100 ° C. measured by a differential scanning calorimeter (hereinafter, referred to as DSC). A copolymer of ethylene and propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, decene-1, or a mixture thereof; And a copolymer with butene-1 is preferably used. Also,
Ethylene used by mixing with the polyethylene resin (A)
The ratio of the α-olefin copolymer (B) is within the range of the weight ratio shown by the expression 4, and when it exceeds this, the effect of the low-temperature heat sealing property is increased, but even when a surfactant is added, the blocking effect is not increased. Occurrence is extremely undesirable.

[0012]

## EQU4 ## 0 ≦ (B) / (A + B) ≦ 0.7

[0013] Ethylene-α-olefin copolymer (B)
A density of 0.860 to 0.900 g / cm ³ is used. When the density is less than 0.860 g / cm ³ , the effect of low-temperature heat sealability is increased, but blocking occurs, which is not preferable. If it exceeds cm ³ , the effect of the low-temperature heat sealability is small, which is not preferable. The MI of the ethylene-α-olefin copolymer used is 0.1 to 0.1.
Those having a range of 20 g / 10 minutes are used, and 0.1 g / 1
If the time is less than 0 minute, the processability is undesirably reduced, and the content is 20 g / 1
If the time exceeds 0 minutes, excessive blocking tends to occur, which is not preferable.

In the combination of the raw materials for the surface layer, a polyethylene resin (A) composed of low-density polyethylene and linear low-density polyethylene, ethylene and butene are used in order to achieve a good balance of low-temperature sealability, adhesion and blocking resistance. The combination of the ethylene-α-olefin copolymer (B) which is the copolymer of -1 is preferably used.

The polypropylene-based soft resin (C) used for the core layer in the present invention comprises a high molecular weight, boiling heptane-soluble atactic polypropylene of 5 to 50% by weight and a boiling heptane-insoluble crystalline isotactic polypropylene of 50 to 95%. It consists of a mixture formed in a polymerization stage of weight%, which is an improvement of the mechanical properties of isotactic polypropylene. As a result, it has heat resistance close to that of general crystalline polypropylene and exhibits flexibility close to that of polyethylene. Therefore, the temperature range in which heat sealing can be performed by having heat resistance is extended to a higher temperature side. Combined with the addition of better stretchability,
The effect of preventing a decrease in transparency, which is considered to be caused by interlayer distortion, and maintaining good transparency even when the recovered product is recycled as a raw material of the film.

The atactic and isotactic polypropylene in the polypropylene-based soft resin (C) may be a homopolymer, a copolymer with another α-olefin such as ethylene or butene-1, or a terpolymer. good. The content of atactic polypropylene in the soft polypropylene resin is 5 to 55% by weight, preferably 5 to 25% by weight.
If it is less than 5% by weight, stretchability, transparency and gloss are inferior, and if it is more than 50% by weight, isotactic polypropylene is reduced, crystallinity is lowered and heat resistance is lowered. It is not preferable.
The atactic polypropylene contained in the polypropylene-based soft resin (C) is preferably soluble in boiling heptane and has a number average molecular weight of about 50,000 to 100,000. Usually, the number average molecular weight of atactic polypropylene produced as a by-product during the production of crystalline polypropylene is about 1
It is less than 000, compared to this and has a high molecular weight.

230 of the soft polypropylene resin (C)
C. Melt flow rate (hereinafter abbreviated as MFR) is 1 to
The melting peak temperature of the polypropylene-based soft resin measured by DSC at 10 g / 10 minutes is preferably 150 ° C. or higher, and the heat of fusion is preferably 20 to 80 kJ / kg. If the melting peak temperature is less than 150 ° C. or the heat of fusion is less than 20 kJ / kg, the heat resistance decreases, and if the heat of fusion exceeds 80 kJ / kg, the stretchability decreases, which is not preferable. As a part of the polypropylene-based soft resin (C), propylene homopolymer and propylene-based copolymer, which are general crystalline polypropylenes, can be used in combination. It is necessary to contain 5% by weight or more. In the present invention, D
Measurement of melting peak temperature and heat of fusion by SC is based on JIS
K7121, according to JIS K7122.

Polybutene-1 (D) used for the core layer
Has an effect of imparting transparency, gloss, and stretchability in suitability for an automatic packaging machine in combination with the above-mentioned polypropylene-based soft resin (C). The polybutene-1 (D) used is different from liquid or waxy polybutene, is crystalline or low-crystalline, is a homopolymer of butene-1 or a copolymer with ethylene or propylene, and has a density of 0.885. Those having an MFR of 0.1 to 30 g / 10 minutes at 190 ° C. and 0.920 g / cm ³ are used. From the viewpoint of transparency, gloss, and stretchability in suitability for an automatic packaging machine, a butene-1 propylene copolymer having a propylene content of 15 to 40 mol% is preferably used.

The present invention can be achieved by mixing a polypropylene-based soft resin (C) and polybutene-1 (D). The weight ratio of (C) / (D) in the core layer is determined by heat resistance, stretch The weight ratio represented by Formula 5 is used from the viewpoint that transparency is easily compatible, but the weight ratio is preferably in the range of 0.6 to 4.0. If (C) / (D) is less than 0.1, heat resistance is lowered and the heat sealing temperature range is narrowed, which is not preferable. On the other hand, when (C) / (D) exceeds 9.0, stretchability and transparency become insufficient.

[0020]

## EQU5 ## 0.10 ≦ (C) / (D) ≦ 9.0

In the present invention, in addition to the polypropylene-based soft resin (C) and the polybutene-1 (D), the above-mentioned polyethylene-based resin (A) and ethylene-α-olefin copolymer (B) may be used in the core layer. It can be used by mixing. Examples of use are when the recovered product is recycled and the surface layer component resin is mixed into the core layer, and when packaging contents having protrusions such as shrimp and crab, it is difficult to tear or openability. In some cases, the film strength (tear strength, impact strength) is adjusted according to the use of the above. The amount of these resins to be added to the core layer is not particularly limited as long as the object of the present invention is not hindered, but the weight ratio represented by Formula 6 is preferable.

[0022]

(A + B) / (A + B + C + D) ≦ 0.7

In the present invention, the nonionic surfactant to be added to at least one or more layers is not particularly limited as long as it is generally commercially available. For example, glycerin fatty acid ester, polyglycerin fatty acid ester, sorbitan fatty acid ester, Polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester,
Propylene glycol fatty acid ester, sucrose fatty acid ester, mono (di or tri) stearyl citrate, pentaerythritol fatty acid ester, trimethylolpropane fatty acid ester, polyoxyethylene glycerin fatty acid ester, polypropylene glycol fatty acid ester, polyoxyethylene alkyl phenyl ether , Polyoxyethylene alkyl ether, polyoxypropylene polyoxyethylene block polymer, polyethylene glycol, polypropylene glycol, polyethylene oxide, alkyldiethanolamide,
One or more nonionic surfactants such as polyoxyethylene alkylamine, an ethylene oxide adduct of castor oil, and isopropyl alcohol are used in combination. Above all, it is preferable to contain a polyoxyethylene sorbitan fatty acid ester from the viewpoint of suppressing a decrease in transparency after shrinkage due to excessive bleeding of the surfactant. The amount of the nonionic surfactant added is 0.1 to 4.0% by weight. If the amount is less than 0.1% by weight, the antifogging property cannot be obtained. Is not preferable because no improvement is observed.

The thickness of the film of the present invention is not particularly limited, but is preferably in the range of 5 to 30 μm, preferably 5 to 20 μm depending on the required film strength and gas barrier properties. Further, the haze is preferably 1.6% or less from the viewpoint of easily identifying the packaged object and not reducing the commercial value.

The object of the present invention is achieved by the above-mentioned three layers of the core layer and the surface layer consisting of the inner layer and the outer layer, and the above-mentioned (A), (B), (C), It is of course possible to provide an intermediate layer made of at least one resin selected from (D) and balance various properties.
In addition, as long as the object of the present invention is not hindered,
It is natural that additives such as a lubricant, an anti-blocking agent, and an antistatic agent are appropriately used for the purpose of providing an effective action.

The laminated stretch shrink film of the present invention is manufactured by a known stretching method. Although the molten resin is extruded from an annular die and stretched without being quenched and solidified by a so-called inflation method, weak heat shrinkage can be imparted. A preferred method is to reheat the solidified unstretched raw material and stretch it at a temperature equal to or lower than the melting point of the polypropylene-based soft resin of the core layer. The stretching ratio is 2 times or more, preferably 2.5 times or more, and more preferably 3 times or more, both vertically and horizontally. Further, in order to more effectively exhibit the stretchability in the horizontal direction of the obtained stretched film, it is better to slightly increase the stretch ratio in the vertical direction. The film stretched as described above and taken out of the stretching device can be subjected to heat treatment such as heat setting and aging as necessary. In order to bleed the antifogging agent more quickly, a treatment such as corona discharge can be performed.

[0027]

The present invention will be described more specifically with reference to the following examples.
However, the present invention is not limited to these implementations unless it exceeds the gist.
It is not limited to the example. In Examples and Comparative Examples
The raw resin used is shown below. A1: Low density polyethylene (high pressure method, density = 0.922)
g / cm^Three , MI = 2.0 g / 10 min) A2: Linear low-density polyethylene (multi-site catalyst, dense
Degree = 0.918 g / cm^ThreeA3: Linear low-density polyethylene (multi-site catalyst, dense
Degree = 0.910 g / cm^Three , MI = 3.0 g / 10 min) A4: Linear low density polyethylene (multi-site catalyst, dense
Degree = 0.916 g / cm^Three , MI = 1.2 g / 10 min) A5: Linear low density polyethylene (single site catalyst,
Density = 0.916 g / cm^Three , MI = 1.5 g / 10
A6) Linear low-density polyethylene (multi-site catalyst, dense
Degree = 0.920 g / cm ^Three , MI = 0.5 g / 10 min) B1: Ethylene-butene-1 copolymer (density = 0.88)
g / cm^Three , MI = 3.6 g / 10 min) C1: polypropylene-based soft resin (atactic polyp)
Lopylene content 10% by weight, MFR (230 ° C.) = 2.
5 g / 10 min, peak melting temperature = 162 ° C., heat of fusion = 6
C2: Polypropylene soft resin (Atactic polyp)
Propylene content 30% by weight, MFR (230 ° C.) = 2.
5 g / 10 min, peak melting temperature = 161 ° C., heat of fusion = 5
0 kJ / kg) D1: Polybutene-1 homopolymer (density = 0.915 g)
/ Cm^Three , MFR (190 ° C) = 1.8 g / 10 min, melting
Solution peak temperature = 115 ° C.) D2: butene-1 · propylene copolymer (density = 0.9)
00g / cm^Three , MFR (190 ° C.) = 1.0 g / 10
D3: butene-1 · ethylene copolymer (density = 0.89)
0 g / cm^Three , MFR (190 ° C.) = 0.2 g / 10
E1, propylene homopolymer (MFR (230 ° C.) = Min, melting peak temperature = 86 ° C.)
2.4 g / 10 min, peak melting temperature = 162 ° C., heat of fusion
= 96 kJ / kg) E2: Propylene / ethylene random copolymer (MFR
(230 ° C.) = 2.4 g / 10 min, melting peak temperature = 1
44 ° C, heat of fusion = 70 kJ / kg)

The measurement of each physical property shown in this example was obtained by the following methods. (1) Haze Measured according to JIS-K7105. (2) Gloss It was measured according to JIS-K7105. (3) Suitability for stretch type automatic wrapping machine Two croquettes having a height of 123 mm, a length of 150 mm, and a depth of 18 mm are placed on a polystyrene raised bottom tray, and two croquettes having a height of 25 mm are provided. The packaging test was carried out at a packaging speed of 30 pieces / min at 30 pieces by a pillow type stretch automatic packaging machine, and the suitability for bag making and the heat sealing temperature range were examined. Evaluation of suitability for bag making
The following criteria were used to determine whether the tray was deformed or damaged in the bag making section.・ ・ ・: A beautiful finish can be obtained without troubles such as cracking or deformation of the tray during bag making (when the packaged material is wrapped while stretching the film). ×: The tray is deformed or damaged during bag making. Also,
The heat seal temperature range is the heat plate seal set temperature (heat seal start temperature), where the entire area of the heat seal begins to heat-weld enough to break the film when it is forcibly peeled off. The hot plate seal set temperature (heat-resistant temperature) before the hole was formed in the film was examined, and the temperature was determined from the difference between the heat-resistant temperature and the heat seal start temperature. The hot plate seal set temperature was increased at a pitch of 5 ° C. (4) Antifogging property After putting 30 ml of water at 18 ° C into a 100 ml beaker,
Cover the top of the beaker with film without wrinkles and fix it. Next, the beaker was placed in hot air adjusted to 110 ° C. for 5 minutes.
Heat shrink for 2 seconds. Thereafter, the film was left in an open showcase at 5 ° C. for 1 hour, and the degree of cloudiness of the film was observed.・ ・ ・: No fogging Δ: some water droplets are present, but the inside of the beaker is visible. ×: The entire surface is cloudy and the inside of the beaker cannot be seen.

Example 1 A nonionic surfactant polyoxyethylene (n = 20) sorbitan monopalmitate 0.2% by weight and diglycerin fatty acid ester 1.8 were added to the raw material resins having the compounding ratios shown in Table 1.
The composition for the surface layer and the composition for the core layer to which weight% was added were melt-kneaded at 170 ° C. to 240 ° C. with three extruders, and the thickness after stretching was 13 μm. The inner layer): core layer: surface layer (outer layer) = 1: 5: 1, the extruding amount of each extruder was adjusted, and extruded downward from the slit of a three-layer annular die maintained at 240 ° C. The diameter of the slit of the annular die was 75 mm, and the gap of the slit was 0.8 mm. The extruded three-layered fused tubular film is mounted directly under the die. The outer surface of a cylindrical mandrel having an outer diameter of 76 mm and circulating cooling water at 20 ° C inside is slid while passing the outer surface through a water tank. Water-cooled, cooled to room temperature and taken off, about 75 mm in diameter and 2 in thickness
A 45 μm tubular unstretched film was obtained. This tubular unstretched film was guided to the tubular biaxial stretching apparatus shown in FIG. 1 and expanded and stretched. At this time, the voltage and current of the annular infrared heater of the preheater 4 were adjusted, and the film temperature at the outlet of the preheater was adjusted. The eight annular infrared heaters of the main heater 5 are divided into four sections, the voltage and current are adjusted to heat the film, and the low-speed nip roll 2, while supplying air flowing along the bubble from below the main heater, Pressurized air is fed into the tubular film between the high-speed nip rolls 3, and the air is bubble-stretched to 5.0 times in length and 4.0 times in width (20 times in area stretching ratio) depending on the peripheral speed ratio of the low-speed and high-speed nip rolls, A stretched film of about 13 μm was obtained. The stretchability is good, there is no vertical movement of the stretch point and no swing of the stretch bubble,
Further, a non-uniform stretching state such as necking was not observed. As shown in Table 3, the obtained film had antifogging properties,
Transparency and gloss were good. A packaging test was carried out with a pillow-type stretch automatic packaging machine using a raised bottom tray. As a result, the bag had stretchability, and good bag suitability was obtained without deformation or breakage of the tray in the bag making section. Further, the temperature range of the heat sealing was wide and practical.

Examples 2 to 7 Example 1 was repeated except that the composition of the starting resin was changed as shown in Table 1.
In the same manner as in the above, a laminated stretch shrink film was manufactured. The stretchability was good in each case, there was no vertical movement of the stretch point and no swing of the stretch bubble, and no uneven stretching state such as necking was observed. As shown in Table 3, the obtained film had good antifogging property, transparency and gloss. A packaging test was carried out with a pillow-type stretch automatic packaging machine using a raised bottom tray. As a result, the bag had stretchability, and good bag suitability was obtained without deformation or breakage of the tray in the bag making section. Further, the temperature range of the heat sealing was wide and practical.

Example 8 The film produced in Example 1 was pulverized and made into coarse granules as a recovered product, and laminated in the same manner as in Example 1 except that the composition of the raw material resin was changed as shown in Table 1. A stretch shrink film was manufactured. The stretchability was good in each case, there was no vertical movement of the stretch point and no swing of the stretch bubble, and no uneven stretching state such as necking was observed. As shown in Table 3, the obtained film had good antifogging property, transparency and gloss. A packaging test was carried out with a pillow-type stretch automatic packaging machine using a raised bottom tray. As a result, the bag had stretchability, and good bag suitability was obtained without deformation or breakage of the tray in the bag making section. Further, the temperature range of the heat sealing was wide and practical.

Comparative Example 1 Example 1 was repeated except that the raw material resin composition was changed as shown in Table 2.
In the same manner as in the above, a laminated stretch shrink film was manufactured. The stretchability was good in each case, there was no vertical movement of the stretch point and no swing of the stretch bubble, and no uneven stretching state such as necking was observed. As shown in Table 3, the obtained film had good antifogging property, transparency and gloss. A packaging test was carried out with a pillow-type stretch automatic packaging machine using a raised bottom tray. As a result, the bag had stretchability, and good bag suitability was obtained without deformation or breakage of the tray in the bag making section. However, the heat sealing temperature range was narrow, and the practicality was insufficient.

Comparative Example 2 Example 1 was repeated except that the composition of the starting resin was changed as shown in Table 2.
In the same manner as in the above, a laminated stretch shrink film was manufactured. The stretchability was good in each case, there was no vertical movement of the stretch point and no swing of the stretch bubble, and no uneven stretching state such as necking was observed. As shown in Table 3, the obtained film had good antifogging properties. The transparency and gloss were slightly inferior to the films obtained in the examples. When a packaging test was conducted using a raised bottom tray with a pillow type stretch automatic packaging machine, the stretchability was insufficient and the tray was deformed and damaged in the bag making part, and good bag making suitability was not obtained. . The heat sealing temperature range was wide.

COMPARATIVE EXAMPLE 3 The film produced in Comparative Example 2 was pulverized and made into a coarse granule as a recovered product, and laminated as in Example 1 except that the composition of the raw material resin was changed as shown in Table 2. A stretch shrink film was manufactured. The stretchability was good in each case, there was no vertical movement of the stretch point and no swing of the stretch bubble, and no uneven stretching state such as necking was observed. As shown in Table 3, the obtained film had good anti-fogging properties, but transparency and
The gloss was reduced. When a packaging test was conducted using a raised bottom tray with a pillow type stretch automatic packaging machine, the stretchability was insufficient and the tray was deformed and damaged in the bag making part, and good bag making suitability was not obtained. . The heat sealing temperature range was wide.

Comparative Example 4 Example 1 except that the composition of the raw material resin was changed as shown in Table 2.
In the same manner as in the above, a laminated stretch shrink film was manufactured. The stretchability was good in each case, there was no vertical movement of the stretch point and no swing of the stretch bubble, and no uneven stretching state such as necking was observed. As shown in Table 3, the obtained film had good antifogging properties. The transparency and gloss were slightly inferior to the films obtained in the examples. When a packaging test was conducted using a raised bottom tray with a pillow type stretch automatic packaging machine, the stretchability was insufficient and the tray was deformed and damaged in the bag making part, and good bag making suitability was not obtained. . The heat sealing temperature range was wide.

COMPARATIVE EXAMPLE 5 The film produced in Comparative Example 4 was pulverized to obtain a granular product as a recovered product, and the lamination was performed in the same manner as in Example 1 except that the composition of the raw material resin was changed as shown in Table 2. A stretch shrink film was manufactured. The stretchability was good in each case, there was no vertical movement of the stretch point and no swing of the stretch bubble, and no uneven stretching state such as necking was observed. As shown in Table 3, the obtained film had good anti-fogging properties, but transparency and
The gloss was reduced. When a packaging test was performed using a raised bottom tray with a pillow type stretch automatic packaging machine, the stretchability was insufficient, and the tray was deformed in the bag making portion, and good bag making suitability was not obtained. The heat sealing temperature range was wide.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

FIG.

[0041]

By using a core layer mainly composed of a mixture of a specific polypropylene-based soft resin and polybutene-1 and a surface layer composed of an ethylene-based resin, at least three or more layers can be formed on trays of various shapes. It is a stretch shrink film that can be sufficiently heat-sealed, has a horizontal stretch property, has excellent transparency and gloss even when recycled products are recycled, and has excellent suitability for automatic packaging machines.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a tubular biaxial stretching apparatus used in Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unstretched raw material 2 Low-speed nip roll 3 High-speed nip roll 4 Preheater 5 Main heater 6 Cooling air ring 7 Folding roll

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI // C08L 23/04 C08L 23/04 23/08 23/08 23/10 23/10 23/20 23/20 B29K 23:00 105: 02 B29L 9:00

Claims (7)

[Claims] 1. A surface layer comprising a mixture of a polyethylene resin of the following (A) and an ethylene-α-olefin copolymer of the following (B) in a weight ratio represented by Formula 1; A laminated film of three or more layers having a polypropylene-based soft resin and a core layer mainly composed of a mixture of polybutene-1 of the following (D) at a polymerization ratio represented by Formula 2, and at least one layer To 0.1 to 4.0% by weight of a nonionic surfactant composition,
A laminated stretch shrink film that has been stretched more than twice. (A) low density polyethylene, linear low density polyethylene,
At least one or more polyethylene resins selected from ultra-low density polyethylene. (B) an amorphous or differential scanning calorimeter having a density of 0.860 to 0.900 g / cm ³ and a melt index of 0.1 to 20 g / 10 min and a melting peak temperature of 50 to 100;
Low temperature crystalline ethylene-α-olefin copolymer (C) 5 to 50% by weight of atactic polypropylene and 50 to 95% by weight of crystalline isotactic polypropylene
Polypropylene soft resin consisting of a mixture of (D) polybutene-1 (1) 0 ≦ (B) / (A + B) ≦ 0.7 (2) 0.10 ≦ (C) / (D) ≦ 9.0 2. The mixture of the core layer is a mixture in which (A) a polyethylene-based resin and / or (B) an ethylene-α-olefin copolymer is further blended in a blending ratio represented by Formula 3. The laminated stretch shrink film according to the above. (A + B) / (A + B + C + D) ≦ 0.7 3. The laminated stretch shrink film according to claim 1, wherein the film has a thickness of 5 to 30 μm and a haze of 1.6% or less. 4. The laminated stretch shrink film according to claim 1, wherein the polypropylene-based soft resin (C) is a mixture of 75 to 95% by weight of crystalline isotactic polypropylene with 5 to 25% by weight of atactic polypropylene. . 5. The laminated stretch shrink film according to claim 1, wherein the polypropylene-based soft resin (C) has a melting peak temperature of 150 ° C. or higher by a differential scanning calorimeter and a heat of fusion of 20 to 80 kJ / kg. 6. The laminated stretch shrink film according to claim 1, wherein the polybutene-1 (D) is a butene-1 · propylene copolymer having a propylene content of 15 to 40 mol%. 7. The laminated stretch shrink film according to claim 1, wherein the nonionic surfactant contains a polyoxyethylene sorbitan fatty acid ester.