JPH07292129A - Readily tearable film and its production - Google Patents

Abstract

PURPOSE:To obtain a film having a slight unevenness in thickness and high tearing properties in spite of a thin wall. CONSTITUTION:This film 3 is obtained by forming thereof from two or more kinds of thermoplastic resins having different recurring units (e.g. a combination of a styrenic polymer with an olefin-based polymer) under conditions of 2-30mm air gap (A) according to a T-die method. The film contains a dispersed phase dispersed in a continuous phase. The average thickness of the film 3 is about 5-50mum and the unevenness of the thickness based on 1m in the take-off direction of the film 3 is + or -100% based on the average thickness of the film 3.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an easily tearable film useful as a packaging material and a method for producing the film.

[0002]

2. Description of the Related Art Packaging materials are required to have some important basic performances. Examples thereof include protection of contents, transportation in the distribution process, ease of handling, and transmission of product information by printing or the like. Further, in recent years, convenience in use by consumers, for example, opening property and easy tearing property have been demanded.

In pouch packaging and container packaging, perforations, V-cuts, U-cuts, I-cuts, micro-cuts, magic cuts, etc. are often formed in the heat-sealed portion in order to impart tearability. However, even if such perforations are formed, the resistance at the time of tearing is large and the unsealing property is inferior, and in many cases linear tearing does not occur. Also,
When the perforation is formed, depending on the type of contents, it may be affected by the external atmosphere or may adversely affect the external atmosphere.

On the other hand, as an easy-open film, there is known a film which is stretched in one direction to impart easy tearability. For example, JP-A-61-212584, JP-A-62-208349 and JP-A-2-24.
2746 and JP-A-2-258342 disclose a packaging material in which a stretched film highly stretched in one direction is laminated on a paper or film as a base material. In addition, Japanese Patent Publication No. 53-17632 and Japanese Patent Publication No. 53-35832 disclose a film having a tear direction including polypropylene and an ethylene-α-olefin copolymer.

However, when the tearing property is imparted by the stretching treatment, a stretching step is required, which not only increases the cost but also makes it difficult to tear without forming a notch even if the stretching treatment is performed. In addition, the film may be branched and torn to generate whiskers, which may not be able to be neatly and linearly torn in one direction. Further, since the film is stretched, the film is heat-sealed by heat sealing and wrinkles occur, which impairs the appearance of the pouch package or the container package.

In order to solve such a problem, the present inventors have formed a resin composition containing as a main component two or more kinds of thermoplastic resins having different repeating units, and a dispersed phase dispersed in a continuous phase. Proposed a film (Japanese Patent Application No. 5-30
0894). This film can be easily torn in at least one direction without being stretched. Furthermore, compared to the film alone, other physical properties, for example,
Improvements in gas barrier properties, strength, heat resistance, etc. can be expected.

Japanese Unexamined Patent Publication (Kokai) No. 1-153733 discloses linear low-density polyethylene (LLDPE) and a thermoplastic resin which is incompatible with the linear low-density polyethylene and has a solubility coefficient of 9 or more. , A method of producing a film that is easy to tear by hot-melt extruding a resin composition containing a specific ratio. In addition, JP-A-4-1
In JP 9137, two or more kinds of resin compositions which are incompatible with each other and have a large melting point difference, for example, a composition containing nylon with a high melting point and polyolefin with a low melting point are extruded and laminated with a substrate. Discloses obtaining a tearable laminated film.

However, a composition containing two or more resins is
The film formation stability is low, and holes are easily formed in the film during film formation, and periodic streak-like thickness unevenness easily occurs. Particularly, a practical thickness of 50 μm or less (for example, 10 to 30 μm).
When a film of about m) is formed, the above phenomenon appears remarkably. In order to suppress the thickness unevenness and obtain a film having high surface smoothness, the ratio of LLDPE to the thermoplastic resin is the former / the latter = 99/1 to 80 as described in JP-A-1-153733. It is conceivable that the amount of the thermoplastic resin used is greatly limited by setting / 20. However, when the surface smoothness is increased with such a composition ratio, not only the tearability of the film is lowered, but also when the film thickness is reduced, the thickness unevenness is still increased and the surface smoothness is lowered.

[0009]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an easily tearable film having a small thickness unevenness even if it is thin and having excellent tearability, and a method for producing the same.

Another object of the present invention is to provide a method capable of producing a film having high tearability and surface smoothness with high productivity.

[0011]

Means for Solving the Problems As a result of intensive studies to achieve the above-mentioned object, the present inventors have identified an air gap when extrusion molding a resin composition containing two or more thermoplastic resins. It was found that a film having a small thickness unevenness and excellent tearability was obtained by setting the range, and the present invention was completed.

That is, the easily tearable film of the present invention is a film formed of a resin composition containing as a main component two or more kinds of thermoplastic resins having different repeating units, and having a dispersed phase dispersed in a continuous phase. , Average thickness 5 to 50
The thickness unevenness per μm and the film withdrawing direction of 5 m is within ± 100% of the average thickness.

The thermoplastic resin constituting the continuous phase includes
For example, a polymer selected from olefin polymers, styrene polymers, polyesters and polyamides is included, and the thermoplastic resin of the dispersed phase can be selected according to the type of thermoplastic resin constituting the continuous phase. For example, when the continuous phase is an olefin polymer, the dispersed phase can be composed of at least one polymer selected from the group consisting of styrene polymers, polyesters, polyamides, polycarbonates and vinyl polymers. The resin composition may include a compatibilizing agent in addition to the thermoplastic resin forming the continuous phase and the thermoplastic resin forming the dispersed phase.

In the production method of the present invention, a resin composition containing two or more kinds of thermoplastic resins having different repeating units as main components is extruded from a T-die under conditions of an air gap of 2 to 30 mm to form a film. , To produce an easily tearable film. In extrusion molding, a film can be formed without stretching.

The present invention will be described in detail below.

The easily tearable film of the present invention has a sea-island structure composed of a continuous phase and a dispersed phase depending on the constituent components of the film. The continuous phase and the dispersed phase can be formed by forming a resin composition containing two or more kinds of thermoplastic resins having different repeating units as a main component into a film.

Examples of the thermoplastic resin include the following polymers (1) to (14).

(1) Olefin Polymer This polymer includes olefin homopolymers or copolymers. Examples of the olefin include ethylene, propylene, 1-butene, 4-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1 -Decene, 1
-Dodecene, 1-tetradecene, 1-hexadecene, 1
Α-Olefins such as octadecene and 1-eicosene: Other olefins such as isobutene.

The olefin polymer may be a copolymer of an olefin and a copolymerizable monomer. Examples of the copolymerizable monomers include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid, angelic acid, and other ethylenically unsaturated carboxylic acids; maleic anhydride. Ethylenically unsaturated polycarboxylic acids such as acids, citraconic anhydride, itaconic anhydride and their acid anhydrides; acrylic acid esters and methacrylic acid esters; vinyl esters of carboxylic acids (eg vinyl acetate, vinyl propionate, etc.) An ethylenically unsaturated carboxylic acid ester of
Examples thereof include cyclic olefins such as norbornene, ethylidene norbornene and cyclopentadiene; and dienes. The copolymerizable monomer may be used alone or in combination of two or more.

As the diene component, a chain conjugated diene such as 1,3-butadiene or isoprene; 1,4-hexadiene, 1,6-octadiene, 2-methyl-1,5-
Hexadiene, 6-methyl-1,5-heptadiene, 7
Chain non-conjugated dienes such as -methyl-1,6-octadiene; cyclohexadiene, dicyclopentadiene, methyltetrahydroindene, 5-vinylnorbornene, 5
-Ethylidene-2-norbornene, 5-methylene-2-
Cyclic non-conjugated dienes such as norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropylenyl-2-norbornene; 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene Ridene-5-norbornene, 2-propenyl-
Examples include cyclic conjugated dienes such as 2,2-norbornadiene.

Preferred polymers include the following olefinic polymers:

(1a) polyethylene, polypropylene,
Ethylene-propylene copolymer, copolymer of ethylene and / or propylene and other monomer (for example, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene- (meth) acrylic acid copolymer) Copolymer, propylene- (meth) acrylic acid copolymer, etc. (1b) Amorphous or low-crystalline soft copolymer composed of at least two kinds of α-olefins (for example, ethylene and α having 3 to 20 carbon atoms). -Copolymer with olefin, copolymer with propylene and α-olefin having 4 to 20 carbon atoms) (1c) α-olefin-diene copolymer as a soft polymer (for example, ethylene-carbon number) 3 to 20 α-olefin-diene copolymer rubber, propylene-C4
.About.20 α-olefin-diene copolymer rubber, etc.) (1d) Rubber soft polymer (for example, polyisobutylene rubber, polyisoprene rubber, polybutadiene rubber, isoprene-isobutylene copolymer rubber, etc.) (1e) Cyclic A soft polymer having an olefin unit (for example, a copolymer of a cyclic olefin or a cyclic diene and an α-olefin).

Further preferred olefin polymers include
Polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; ethylene-vinyl acetate copolymer; ethylene-ethyl acrylate copolymer; ethylene- (meth) acrylic acid copolymer; polypropylene Propylene- (meth) acrylic acid copolymer; epoxy-modified polyolefin (for example,
Ethylene-glycidyl (meth) acrylate copolymer), carboxyl modified polyolefin (eg ethylene-maleic anhydride copolymer), epoxy and carboxy modified polyolefin (eg ethylene- (meth))
Modified polyolefins such as acrylic acid-maleic anhydride copolymers); ethylene-propylene copolymers; olefin elastomers; ethylene propylene rubber and the like.

Particularly preferred olefin polymers include ethylene among the polymers belonging to (1a) above,
A homopolymer or a copolymer containing propylene as a main component is included. As such an olefin polymer, polyethylene, polypropylene, an ethylene-propylene copolymer, a copolymer of ethylene and / or propylene and a linear or branched α-olefin having about 1 to 6 carbon atoms. Is included. The content of ethylene and / or propylene in the olefin-based copolymer is 65% by weight or more. More specifically, polyethylene, polypropylene and ethylene-propylene copolymer are preferred.

The copolymer is usually a lantam copolymer in many cases. The homopolymer and / or copolymer is
It can also be used as a mixture of two or more kinds.

(2) Halogen-Containing Vinyl Polymer Examples of the halogen-containing vinyl polymer include polyvinyl chloride, polyvinylidene chloride and polyvinyl fluoride (for example,
Polytetrafluoroethylene, polyperfluoropropylene, etc.), homopolymers of halogen-containing monomers such as polychloroprene; vinyl chloride-vinyl acetate copolymer,
Halogen-containing monomer and other monomers such as vinylidene chloride-vinyl acetate copolymer, vinylidene chloride-acrylonitrile copolymer, vinylidene chloride- (meth) acrylic acid copolymer, vinylidene chloride- (meth) acrylic acid ester copolymer Copolymer with; chlorinated polypropylene,
Halogenated polymers such as chlorinated rubber are exemplified.

(3) Acrylic Polymer This polymer includes, for example, acrylic acid, methacrylic acid,
Homopolymers or copolymers of acrylic monomers such as acrylic acid esters, methacrylic acid esters, acrylamide, and acrylonitrile; acrylic monomers, other monomers, and copolymers are included.

Examples of the acrylic homopolymer or copolymer include polyacrylate, polymethacrylate, acrylic acid ester-methacrylic acid ester copolymer, polyacrylamide and polyacrylonitrile. As a copolymer with an acrylic monomer, (meth) acrylic acid ester-styrene copolymer, (meth)
Acrylic acid-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, acrylonitrile-styrene copolymer, acrylonitrile-styrene- (meth)
Examples thereof include acrylic acid ester copolymers. These acrylic polymers can be used alone or as a mixture.

Preferred acrylic polymers include polymethylmethacrylate, (meth) acrylic acid-styrene copolymers, (meth) acrylic acid ester-styrene copolymers and the like.

(4) Vinyl-based Polymer The vinyl-based polymer includes homo- or copolymers of vinyl-based monomers and polymers derived from these polymers. Examples of the vinyl-based monomer include vinyl acetate, vinyl propionate, vinyl crotonate, vinyl laurate, vinyl oleate, vinyl stearate,
Vinyl esters such as vinyl maleate and vinyl benzoate; vinyl ketones such as methyl vinyl ketone and methyl isopropenyl ketone; vinyl ethers such as vinyl methyl ether, vinyl ethyl ether and vinyl isobutyl ether; N-vinylcarbazole, N-vinylpyrrolidone Examples thereof include vinylamines. The vinyl-based monomer may be a copolymer with another copolymerizable monomer (for example, ethylene-vinyl acetate copolymer).

Examples of the polymer derived from the vinyl homopolymer include polyvinyl alcohol, polyvinyl acetals such as polyvinyl formal and polyvinyl butyral, and the like. Examples of the polymer derived from the vinyl-based copolymer include ethylene-vinyl alcohol copolymer derived from an ethylene-vinyl acetate copolymer.

Preferred vinyl copolymers include polyvinyl ester (eg, polyvinyl acetate), polyvinyl ketone, polyvinyl ether, polyvinyl alcohol, polyvinyl acetal, ethylene-vinyl acetate copolymer,
An ethylene-vinyl alcohol copolymer and the like are included.

(5) Aromatic vinyl-based polymer The aromatic vinyl-based polymer includes (5a) styrene-based polymer and (5b) styrene-based monomer-conjugated diene-based copolymer.

(5a) Styrene-based polymer The styrene-based polymer includes homopolymers or copolymers of styrene-based monomers such as styrene, α-methylstyrene and chlorostyrene, styrene-based monomers and vinyl monomers (for example, Copolymers with unsaturated nitriles such as acrylonitrile, (meth) acrylic acid, (meth) acrylic acid esters, α, β-monoolefinic unsaturated carboxylic acids such as maleic anhydride or acid anhydrides or their esters) , Impact-resistant polystyrene (high-impact polystyrene HIPS), impact-resistant styrene-based resin, and the like.

Impact-resistant polystyrene can be obtained by mixing polystyrene with a diene rubber elastomer or by graft-polymerizing a styrene monomer on the diene rubber elastomer. Further, the impact-resistant styrene resin is a diene rubber elastomer such as polybutadiene, an acrylic rubber containing an unsaturated group, a chlorinated polyethylene, an ethylene-vinyl acetate copolymer, a polymer such as ethylene-propylene rubber, a vinyl monomer ( For example,
It can also be obtained by graft-copolymerizing a styrene-based monomer with acrylonitrile or methyl methacrylate).

Preferred styrenic polymers include, for example:
Styrene- (meth) acrylic acid ester copolymers such as polystyrene (GPPS), styrene- (meth) acrylic acid copolymer, methyl methacrylate-styrene copolymer (MAS resin), styrene-maleic anhydride copolymer ,
Styrene-acrylonitrile copolymer (AS resin), impact-resistant polystyrene, impact-resistant styrene-based resin (for example, ABS resin obtained by graft-polymerizing styrene and acrylonitrile onto polybutadiene, AAS resin obtained by graft-polymerizing styrene and acrylonitrile onto acrylic rubber,
ACS resin obtained by graft-polymerizing styrene and acrylonitrile on chlorinated polyethylene, polymer obtained by graft-polymerizing styrene and acrylonitrile on ethylene-vinyl acetate copolymer, polymer obtained by graft-polymerizing styrene and acrylonitrile on ethylene-propylene rubber, styrene on polybutadiene And MBS resin obtained by graft-polymerizing methyl methacrylate). These styrene polymers can be used alone or in combination of two or more.

Particularly preferred styrene-based polymers include highly transparent styrene-based polymers (for example, styrene- (meth) styrene such as polystyrene, styrene- (meth) acrylic acid copolymer, and methyl methacrylate-styrene copolymer). ) Acrylic ester copolymers, styrene-acrylonitrile copolymers, etc.), high-impact polystyrene, high-impact styrene resins, styrene-maleic anhydride copolymers, etc.

Unless otherwise specified, the impact-resistant polystyrene and the impact-resistant styrene resin are generically referred to below,
It is simply referred to as "rubber modified impact polystyrene".

When a highly transparent styrenic polymer is used in combination with, for example, polyester, the transparency is high and
A film having excellent tearability can be obtained. When the styrene polymer is combined with polyester, a film having high tearability not only in the film-drawing direction but also in the direction orthogonal to the film-drawing direction can be obtained.

When used in combination with polyester, the rubber-modified impact-resistant polystyrene is an α, β-unsaturated aliphatic carboxylic acid such as (meth) acrylic acid, or an α, β-unsaturated fat such as maleic anhydride. When modified with a group polyvalent carboxylic acid or an acid anhydride thereof or an ester thereof, the affinity with the polyester is increased and the tearability of the film may be lowered. Therefore, the rubber-modified impact-resistant polystyrene combined with polyester is
It is preferably a copolymer with a monomer other than β-unsaturated aliphatic carboxylic acid, α, β-unsaturated aliphatic polycarboxylic acid or its acid anhydride or its ester.

(5b) Styrenic Monomer-Conjugated Diene Copolymer This copolymer includes a random copolymer, a block copolymer or a hydrogenated copolymer of a styrene monomer and a conjugated diene. included. The copolymer usually constitutes a soft polymer.

Examples of such a copolymer include styrene-
Butadiene copolymer, styrene-butadiene-styrene (SBS) block copolymer, styrene-isoprene block copolymer, styrene-isoprene-styrene (S
IS) block copolymer, styrene-ethylene / butylene-styrene block copolymer, styrene-ethylene
Propylene-styrene block copolymer, hydrogenated styrene-butadiene-styrene block copolymer, hydrogenated styrene-isoprene-styrene block copolymer,
Examples thereof include styrene-butadiene random copolymer.

The hydrogenated copolymer is a copolymer obtained by hydrogenating some or all of the double bonds existing in the above copolymer. The benzene ring may also be hydrogenated by hydrogenation to form a cyclohexane ring, but usually, a double bond derived from a conjugated diene is often hydrogenated. The hydrogenation rate is usually 50% or more, preferably 70% or more. Preferred hydrogenated copolymers include hydrogenated styrene-butadiene-styrene block copolymers, hydrogenated styrene-isoprene-styrene block copolymers and the like.

The copolymer may be modified with maleic anhydride, (meth) acrylic acid, (meth) acrylic acid ester, glycidyl (meth) acrylate and the like.

(6) Polycarbonate Polycarbonate includes a polymer obtained by reacting a dihydroxy compound with a carbonic acid ester such as phosgene or diphenyl carbonate. The dihydroxy compound may be an alicyclic compound or the like, but is preferably a bisphenol compound.

As the bisphenol compound, bis (4
-Hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 2 , 2-
Bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) -3-methylbutane, 2,
2-bis (4-hydroxyphenyl) hexane, 2,2
-Bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxy-3-methyl) Phenyl) methane, 1,1-bis (4-hydroxy-3-methylphenyl) ethane, 2,2-bis (4-hydroxy-)
3-methylphenyl) propane, 2,2-bis (4-hydroxy-3-ethylphenyl) propane, 2,2-bis (4-hydroxy-3-isopropylphenyl) propane, 2,2-bis (4- Hydroxy-3-sec-butylphenyl) propane, bis (4-hydroxyphenyl) phenylmethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 1,1-bis (4-hydroxyphenyl) -1 -Phenyl propane, bis (4
-Hydroxyphenyl) diphenylmethane, bis (4-
Hydroxyphenyl) dibenzylmethane, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxydiphenyl sulfide and the like.

Preferred polycarbonates include bisphenol A type polycarbonate.

(7) Polyester The polyester is a polyester derived from dicarboxylic acid or its lower alkyl ester and glycol;
A polyester obtained by using an oxycarboxylic acid, and optionally a dicarboxylic acid or a lower alkyl ester and / or glycol thereof in combination; a polyester derived from a lactone is included.

Examples of the dicarboxylic acid component include aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid and sebacic acid; alicyclic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid. Terephthalic acid, isophthalic acid, phthalic acid, phthalic anhydride, p-β-ethoxybenzoic acid, 2,6-naphthalenedicarboxylic acid, di (p-carboxyphenyl) ketone, di (p-carboxyphenyl) ether, bis ( Four
-Carboxyphenol) ethane, aromatic dicarboxylic acids such as 5-sodium sulfoisophthalic acid, and the like.

As the glycol component, ethylene glycol, diethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol,
Aliphatic diols such as polypropylene glycol, butanediol, polytetramethylene glycol, hexanediol, neopentyl glycol; alicyclic diols such as cyclohexanediol; aromatic diols such as bisphenol A; alkylene oxides of bisphenol A (eg ethylene oxide) Examples include adducts.

Examples of the oxycarboxylic acid component include p-oxybenzoic acid and the like.

Examples of the lactone include propiolactone, butyrolactone, valerolactone, caprolactone, laurolactone, palmitolactone, stearolactone and the like.

Polyester also includes polyester elastomers. This elastomer contains polyester as a main component and may have a segment such as polytetramethylene glycol.

The polyester may contain a small amount of a unit of a copolymerization component containing an amide bond, a urethane bond, an ether bond and a carbonate bond.

Preferred polyesters include polyesters containing terephthalic acid units, for example, polyalkylene terephthalates such as polyethylene terephthalate and polybutylene terephthalate, poly-1,4-dimethylol-.
Cyclohexane terephthalate and the like are included. These polyesters usually have crystallinity. In addition,
The crystalline polyester may be modified with a dicarboxylic acid component and / or a glycol component other than the constituent components.

(8) Polyamides Polyamides include polyamides derived from diamines and dicarboxylic acids; polyamides obtained by using aminocarboxylic acids and, if necessary, diamines and / or dicarboxylic acids in combination; lactam-derived polyamides. Is included. Polyamides also include copolyamides.

As the diamine, general formula H ₂ N-L-N is used.
H ₂ (wherein L is a divalent aliphatic group, a divalent alicyclic group or a divalent aromatic group, and these groups may have a substituent) A compound is used.

Examples of the diamine include trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine and octamethylenediamine. Aliphatic diamines; aromatic diamines such as phenylenediamine and metaxylylenediamine; bis (4-amino-3-
Alicyclic diamines such as methylcyclohexyl) methane are mentioned. These diamines may be used alone or in combination of two or more.

As the dicarboxylic acid, a general formula HOOC-
M-COOH (in the formula, M is a divalent aliphatic group, a divalent alicyclic group or a divalent aromatic group, and these groups may have a substituent) The compound and its acid anhydride are used.

Examples of the dicarboxylic acid include phthalic acid, phthalic anhydride, aromatic dicarboxylic acids such as isophthalic acid and terephthalic acid; alicyclic dicarboxylic acids such as cyclohexane-1,4-dicarboxylic acid and cyclohexane-1,3-dicarboxylic acid. Acids; aliphatic dicarboxylic acids such as glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and octadecanedioic acid; and dimerized fatty acids. The dimerized fatty acid is a polymerized fatty acid obtained by polymerizing a fatty acid, for example, an unsaturated natural or synthetic basic fatty acid having 8 to 24 carbon atoms. Examples of such a dimerized fatty acid include a dimer of linolenic acid.

Examples of the aminocarboxylic acid include aminoheptanoic acid, aminononanoic acid, aminoundecanoic acid and the like. Aminocarboxylic acids can also be used alone or in combination of two or more.

Examples of the lactam include butyrolactam, vivarolactam, caprolactam, capryllactam, enantolactam, undecanolactam, dodecaractam and the like. These lactams can also be used alone or in combination of two or more.

As the polyamide, nylon 46, nylon 6, nylon 66, nylon 610, nylon 61
2, nylon 11, nylon 12, polyamide obtained from terephthalic acid and / or isophthalic acid and hexamethylenediamine, polyamide obtained from adipic acid and metaxylylenediamine, obtained from terephthalic acid, adipic acid and hexamethylenediamine Examples thereof include a polyamide, a copolymerized polyamide containing a dimerized fatty acid as a copolymerization component, and a copolyamide formed by at least two different polyamide forming components among these. These polyamides can be used alone or as a mixture. The polyamide also includes polyamide elastomer.

Preferred polyamides include nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, and the like. When nylon 11 or nylon 12 is used as the polyamide, an easily tearable film having high transparency can be obtained even when combined with an olefin polymer.

(9) Polymer Derived from Epoxide This polymer includes homopolymers or copolymers of alkylene oxides such as ethylene oxide and propylene oxide. Examples of the polymer include polyethylene oxide, polypropylene oxide, and a copolymer of ethylene oxide and propylene oxide.

(10) Polyacetal Polyacetal includes homopolymers of aldehydes such as formaldehyde and trioxane, or copolymers containing the above-mentioned monomer as a main component. As the copolymer, formaldehyde or trioxane and other monomers (for example, other aldehydes such as acetaldehyde, ethylene oxide, cyclic ethers such as 1,3-dioxolane, cyclic carbonates, epoxides, isocyanates,
And a copolymer with a vinyl compound). The end of the polyacetal may be esterified with an organic acid such as acetic acid.

(11) Polyphenylene oxide Polyphenylene oxide includes homopolymers and copolymers. As the homopolymer, poly (2,6-dimethyl-1,4-phenylene) oxide, poly (2-methyl-6-ethyl-1,4-phenylene) oxide, poly (2,6-diethyl-1, 4-phenylene) oxide,
Poly (2-methyl-6-n-propyl-1,4-phenylene) oxide, poly (2,6-di-n-propyl-)
1,4-phenylene) oxide, poly (2-methyl-6)
-N-butyl-1,4-phenylene) oxide, poly (2-ethyl-6-isopropyl-1,4-phenylene) oxide, poly (2-methyl-6-chloro-1,4)
-Phenylene) oxide, poly (2-methyl-6-hydroxyethyl-1,4-phenylene) oxide, poly (2-methyl-6-chloroethyl-1,4-phenylene) oxide and the like.

Examples of the polyphenylene oxide copolymer include benzene formaldehyde resin and alkylbenzene formaldehyde resin, and cresol and p-tert-
An alkylphenol-modified benzene-formaldehyde resin block obtained by reacting an alkylphenol such as butylphenol, and a modified polyphenylene oxide copolymer composed of a polyphenylene oxide block as a main structure, a polyphenylene oxide or a copolymer thereof containing a styrene-based polymer. Examples include modified graft copolymers that are grafted.

(12) Polysulfone Polysulfone includes thermoplastic polysulfone having a structural unit represented by the following general formula.

-(Ar ² --B--Ar ² --SO ₂ )-or-(Ar ² --SO ₂ )-(wherein Ar ² represents an arylene group (eg, phenylene group), B represents an oxygen atom, (Sulfur atom or aromatic diol residue is shown) Examples of polysulfone include poly (ether sulfone) and poly (4,4′-bisphenol ether sulfone).

(13) Polyurethane Polyurethane includes a polymer obtained by reacting a diisocyanate compound such as tolylene diisocyanate with the glycol and / or the diamine.
Also, polyurethane has polyurethane as the main component,
Also included are polyurethane elastomers that may have segments such as polytetramethylene glycol.

(14) Other Thermoplastic Resins Examples of the other thermoplastic resins include (14a) polyarylate, (14b) polyphenylene sulfide,
Examples include (14c) polyether sulfone, (14d) polyether ether ketone, and (14e) polyoxybenzylene.

In the present invention, among these thermoplastic resins, two or more kinds of thermoplastic resins having different repeating units are used in an appropriate combination. Preferably, a plurality of thermoplastic resins in which the continuous phase and the dispersed phase are incompatible with each other, particularly different thermoplastic resins are combined.

As long as a sea-island structure is formed, two or more kinds of thermoplastic resins of the same series may be used. That is,
The two or more thermoplastic resins may have some repeating units that are the same or similar, such as a combination of polybutylene terephthalate and polyethylene terephthalate. Further, two or more kinds of thermoplastic resins may be partially compatible with each other. Preferably, the solubility parameter SP, which is a measure of compatibility, often contains, as a main component, a thermoplastic resin having a difference of about 0.2 to 7, preferably about 0.5 to 5.

The solubility parameter of the thermoplastic resin varies depending on not only the repeating unit but also the presence or absence of modification, and the repeating unit of the commercially available thermoplastic resin is often unclear. Therefore, the solubility parameter of the thermoplastic resin cannot be unconditionally determined, but the solubility parameter of a general thermoplastic resin will be described for reference.

Preferred thermoplastic resin compositions are: (a) olefin polymer (SP = 7.5-8.5), (b) acrylic polymer (SP = 9-10), (c) styrene polymer. Polymer (SP = 8 to 10.5), (d) polycarbonate, (e) polyester (SP = 10 to 12), (f)
Polyamide (SP = 12.5 to 14.5) can be appropriately combined and configured.

The preferred thermoplastic resin constituting the continuous phase is a polymer excellent in film forming ability, for example, an olefin polymer (especially polyethylene, polypropylene, ethylene-propylene copolymer, etc.), a styrene polymer (especially). , Polystyrene, rubber-modified impact-resistant polystyrene, etc.), polycarbonate (especially bisphenol A type polycarbonate etc.), polyester (especially polyethylene terephthalate, polybutylene terephthalate, poly-1,4-dimethylol-cyclohexane terephthalate etc.) and polyamide (especially, Nylon 6, nylon 66, nylon 610, nylon 612, nylon 11, nylon 12, etc.). More preferably, the continuous phase of the film may consist of olefinic polymers, styrenic polymers and polyesters.

More specifically, (a) the dispersed phase dispersed in the continuous phase formed of an olefin polymer is (b) an acrylic polymer, (c) a styrene polymer, (d) a polycarbonate, It can be formed of (e) polyester, (f) polyamide and (g) vinyl-based polymer. A preferred dispersed phase can be composed of at least one thermoplastic resin of (c) styrene polymer, (d) polycarbonate, (e) polyester, (f) polyamide and (g) vinyl polymer.

(C) The dispersed phase dispersed in the continuous phase formed of the styrene polymer is (a) the olefin polymer,
(B) acrylic polymer, (d) polycarbonate,
It can be formed of (e) polyester and (f) polyamide. A preferable dispersed phase is (a) an olefin polymer,
It can be composed of at least one thermoplastic resin selected from (e) polyester and (f) polyamide.

Further, the thermoplastic resin which is preferably combined with the polyester (e) which forms the continuous phase and which forms the dispersed phase is (a) an olefin polymer, (b) an acrylic polymer, (c) styrene. It is at least one kind of thermoplastic resin selected from a polymer, (d) polycarbonate, and (f) polyamide.

Further, the thermoplastic resin which is preferably combined with the (f) polyamide forming the continuous phase and forming the dispersed phase is (a) an olefin polymer, (c) a styrene polymer, or (d) a polycarbonate. And (e) at least one thermoplastic resin selected from polyesters.

The ratio of the thermoplastic resin forming the continuous phase to the thermoplastic resin forming the dispersed phase is usually continuous phase / dispersed phase = 35 to 98/2 to 65 (wt%), preferably 50.
~ 95/5 to 50 (wt%), more preferably 60 to
It is about 90/10 to 40 (% by weight). When it is out of the above range, the tearability of the film is apt to decrease.

To these resin compositions, a component comprising a dispersant such as a compatibilizing agent or a surfactant having an affinity or compatibility with the continuous phase and / or the dispersed phase may be added. Addition of such components has the advantage that the dispersed resin particles can be made finer, the tear strength of the film can be adjusted, and the properties of the film can be improved.

As the compatibilizing agent, a polymer having a structural unit of the thermoplastic resin constituting the continuous phase and a unit having the same or a similar unit as the structural unit of the thermoplastic resin constituting the dispersed phase is usually used. Further, the solubility parameter of the compatibilizing agent is often in the middle or part of the solubility parameter of the thermoplastic resin forming the continuous phase and the solubility parameter of the thermoplastic resin forming the dispersed phase. Therefore, the compatibilizer can be appropriately selected depending on the types of the two or more thermoplastic resins.

The compatibilizer which can be used in combination with the thermoplastic resin constituting the continuous phase and the thermoplastic resin constituting the dispersed phase will be described below.

When the (a) olefin polymer and (b) acrylic polymer and / or (e) polyester are combined, the compatibilizing agent may be a modified polyolefin (eg, maleic anhydride modified polyolefin, (meth ) Acrylic ester-olefin copolymer, glycidyl (meth) acrylate-olefin copolymer) and the like.

When the (a) olefin-based polymer and the (c) styrene-based polymer are combined, the compatibilizing agent is, for example, hydrogenated or modified styrene-based monomer-conjugated diene-based copolymer. Polymer (for example, styrene-butadiene block copolymer, styrene-diene-styrene block copolymer, styrene-olefin- (styrene) block copolymer, maleic anhydride-modified styrene-diene-styrene block copolymer, glycidyl ( (Meth) acrylate-modified styrene-diene-styrene block copolymers), olefin- (meth) acrylic acid ester copolymers, olefin polymers having cyclic olefin units, chlorinated polyolefins, and the like.

When the (a) olefin polymer and (d) polycarbonate are combined, the compatibilizing agent may be a modified polyolefin (eg, maleic anhydride-olefin copolymer, glycidyl (meth) acrylate-olefin copolymer). ), An olefin polymer having a cyclic olefin unit, an olefin elastomer, a hydrogenated or optionally modified styrene monomer-conjugated diene soft copolymer, and the like.

When the (a) olefin polymer and the (f) polyamide are combined, the compatibilizer may be a modified polyolefin (eg, (meth) acrylic acid-olefin copolymer, maleic anhydride-olefin copolymer). Examples thereof include a polymer, a glycidyl (meth) acrylate-olefin copolymer), and an olefin polymer having a cyclic olefin unit.

As the compatibilizer, a copolymer of the above-mentioned olefin and a styrene-based monomer (for example, "Dailark" manufactured by Sekisui Chemical Co., Ltd., "Rurex" manufactured by Dainippon Ink and Chemicals, Inc.) Etc.); A copolymer of an olefin, a styrene-based monomer, an α, β-ethylenically unsaturated carboxylic acid and / or an α, β-ethylenically unsaturated polyvalent carboxylic acid or an acid anhydride thereof (for example, Mitsubishi Kasei ( "Novatech AP" manufactured by Mitsubishi Petrochemical Co., Ltd., etc.) are also included. It should be noted that these compatibilizers are also included in the category of modified polyolefin.

When the acrylic polymer (b) and the styrene polymer (c) are combined, the compatibilizing agent may be a styrene- (meth) acrylic acid ester copolymer or styrene-
Examples thereof include (meth) acrylic acid copolymers, maleic anhydride-styrene copolymers, hydrogenated or optionally modified styrene-based monomer-conjugated diene-based soft copolymers.

When the acrylic polymer (b) and the polycarbonate (d) are combined, the compatibilizing agent is a styrene- (meth) acrylic acid ester copolymer, a hydrogenated or optionally modified styrene-based polymer. Examples thereof include a monomer-conjugated diene-based soft copolymer.

When the acrylic polymer (b) and the polyester (e) are combined, the compatibilizing agent may be a modified poly (meth) acrylic acid ester (eg, oxazoline-modified poly (meth) acrylic acid ester, maleic anhydride). Acid- (meth) acrylic acid ester copolymer, glycidyl (meth)
Acrylate- (meth) acrylic acid ester copolymers, etc., polyester elastomers, etc. are included.

When the acrylic polymer (b) and the polyamide (e) are combined, examples of the compatibilizing agent include a carboxyl-modified acrylic polymer and a maleic anhydride-modified acrylic polymer.

When the (c) styrene-based polymer and the (d) polycarbonate are combined, examples of the compatibilizing agent include vinyl oxazoline-styrene copolymer, epoxy modified polystyrene (eg, glycidyl (meth) acrylate-styrene). Copolymers) and the like.

When the (c) styrene-based polymer and (e) polyester are combined, the compatibilizing agent may be modified polystyrene (eg, oxazoline-modified polystyrene, maleic anhydride-styrene (acrylonitrile) copolymer,
(Meth) acrylic acid-styrene copolymer, glycidyl (meth) acrylate-styrene (acrylonitrile)
Copolymer) and the like.

When the (c) styrene-based polymer and the (f) polyamide are combined, the compatibilizing agent is modified polystyrene, modified acrylonitrile-styrene copolymer, (meth) acrylic acid-styrene copolymer, or anhydrous. Maleic acid-
Styrene copolymer, glycidyl (meth) acrylate-
Examples thereof include styrene copolymers.

When the (d) polycarbonate and the (e) polyester are combined, examples of the compatibilizing agent include carboxyl-modified polyester and epoxy-modified polyester.

When (d) polycarbonate and (f) polyamide are combined, the compatibilizing agent is modified polyamide,
Modified styrene polymers and the like are included.

When the polyester (e) and the polyamide (f) are combined, the compatibilizer includes carboxyl-modified polyester, epoxy-modified polyester and the like.

The compatibilizer may be used alone or in combination according to the kind of the thermoplastic resin forming the continuous phase and the thermoplastic resin forming the dispersed phase.

The amount of the compatibilizer added is 1 in total of the thermoplastic resin constituting the continuous phase and the thermoplastic resin constituting the dispersed phase.
It is 0.1 to 30 parts by weight, preferably 0.5 to 25 parts by weight, more preferably 1 to 20 parts by weight, and often 2 to 10 parts by weight with respect to 00 parts by weight.
If the amount of the compatibilizer added is less than 0.1 parts by weight, the effect of addition is small, and if it exceeds 30 parts by weight, the sea-island structure may disappear.

The dispersed phase, which is finely dispersed in the continuous phase of the film, is oriented in a rod-like or fibrous form with an average aspect ratio of 3 or more along the take-up direction of the film. When dispersed in a rod shape, the aspect ratio of the dispersed phase is 3 or more, preferably about 3 to 50 (for example, 4 to
When it is dispersed in a fibrous form, the aspect ratio of the dispersed phase may be 50 or more. When the aspect ratio of the dispersed phase is less than 3, the tearability of the film is reduced. When the aspect ratio of the dispersed phase is 3 or more, the shape of the dispersed phase is not particularly limited. That is, when the aspect ratio of the disperse phase is 3 or more, the film is excellent in tearability even when the disperse phase is not limited to a layered form but an island form or the like in the cross section in the film taking direction.

A film in which the dispersed phase has a layered structure in the cross section in the film take-off direction is also excellent in tearability. The thickness of one layer of the dispersed phase is 1 μm or less, preferably 0.01 to 1 μm, more preferably 0.1 to 0.
It is about 8 μm. When the dispersed phase is spherical rather than layered, a large force is required for tearing. Further, even if the film is torn, it may be obliquely torn or beard may occur. The thickness of the layered dispersed phase is 5 times the thickness of the film.
% Or less, preferably 0.1 to 3%, and more preferably about 0.25 to 2.5%.

The preferred disperse phase is usually rod-like or fibrous having an aspect ratio of 3 or more (preferably about 3 to 50), and dispersed in a layer-like or island-like form in the cross section in the film take-up direction. In many cases.

The film having such a fine structure is
Even if incompatible resins are combined, the transparency is high, and the initial tear resistance and tear propagation resistance are extremely small,
It can be easily torn straight.

The aspect ratio of the dispersed particles when viewed from the film surface can be calculated based on the photographs taken by using a transmission electron microscope (TEM), a scanning electron microscope (SEM), a confocal laser microscope, and an optical microscope. . Also,
It is also possible to more clearly observe the structure of the dispersed particles by etching the dispersed component using an appropriate organic solvent or the like.

The average aspect ratio is the number average value of the ratio of the length L in the longitudinal direction of the dispersed particles to the minimum width W of the dispersed particles, as shown in the following formula.

[0109] The shape and dispersed state of the dispersed particles in the film, the cross-section of the ultrathin slice sliced parallel to the side end face of the film,
It can be examined by observing with TEM. It can also be examined by etching the disperse component of the cut end face with an appropriate organic solvent and observing with a SEM or a confocal laser microscope. The shape and thickness of the dispersed particles when observed from the side end surface of the film can be determined based on a micrograph.

The unstretched film having such a microstructure has not only sufficient practical strength in the film-taking direction and the direction orthogonal to the drawing direction, but also at least one of the above-mentioned ones. In the direction of, there is a feature that it is easy to tear by a hand in a substantially straight line without a beard.

In another embodiment of the present invention, the film formed of the following composition has a feature that it exhibits high tearability even if the dispersed phase having a sea-island structure does not have the aspect ratio or the thickness described above. . In addition, normally, in this film, the dispersed phase is oriented in the take-up direction of the film. The dispersed phase often has the aspect ratio and / or the thickness or shape. That is, the dispersed phase has (1) an average aspect ratio of 3 or more (for example, about 3 to 50) in a rod shape or a fibrous shape, (2) an island shape, or a thickness of 1 μm or less (for example, about 0.01 to 1 μm). Are dispersed in layers,
Or (3) In many cases, the average aspect ratio is 3 or more, and the particles are dispersed in an island shape or a layer shape having a thickness of 1 μm or less.

A preferred composition containing a plurality of thermoplastic resins having different repeating units includes the following combinations.

(I) A combination of (c) a styrene polymer and (e) a polyester, (II) a combination of (c) a styrene polymer and (a) an olefin polymer, (III) (c) A combination of a styrene polymer and (f) polyamide, (IV)
(A) combination of olefin polymer and (f) polyamide, (V) combination of (a) olefin polymer and (e) polyester, and (VI) (a) olefin polymer and (g) Combination with vinyl polymer.

In the combination (I), it is preferable to use a transparent styrene polymer or a rubber-modified impact-resistant polystyrene as the styrene polymer. When (I) a styrene polymer and a polyester are used in combination, the ratio of the two is, for example, styrene polymer / polyester = 10 to 98/90 to 2 (wt%), preferably 15 to 85/85. 15 (wt%), more preferably about 20-80 / 80-20 (wt%), and
It is often about 75/75 to 25 (% by weight). In such a composition, a film using a transparent styrene-based polymer has high transparency, high tear resistance, and high heat resistance.

In the combination (I), when rubber modified impact resistant polystyrene and polyester are combined, the ratio of the two is, for example, rubber modified impact resistant polystyrene / polyester = 50 to 98/2 to 50 ( % By weight), preferably about 60 to 90/10 to 40 (% by weight).

In the combination of (II) above, as the styrene-based polymer, the above various polymers can be used.
Preferred styrenic polymers include, for example, polystyrene, rubber modified high impact polystyrene and mixtures thereof.

The ratio of the styrene polymer to the olefin polymer is, for example, styrene polymer / olefin polymer = 2 to 90/98 to 10 (wt%), preferably 1
0-90 / 90-10 (wt%), more preferably 2
0 to 80/80 to 20 (% by weight) and 25 to 7
It is often about 5/75 to 25 (% by weight).

By adding, for example, a hydrogenated styrene-based monomer-conjugated diene-based copolymer to the styrene-based polymer and the olefin-based polymer, the easy tearing property of the film is further improved. The hydrogenated copolymer is
It seems to function as a compatibilizer.

The proportion of the hydrogenated copolymer is, for example, 0.5 to 25 parts by weight, preferably 1 to 20 parts by weight, based on 100 parts by weight of the resin composition of the styrene polymer and the olefin polymer. Parts, more preferably about 2 to 10 parts by weight.

In the combination of the above (III), the ratio of the styrenic polymer and the polyamide can be appropriately selected. For example, styrene polymer / polyamide = 55 to 98/4.
5 to 2 (% by weight), preferably 60 to 85/40 to 15
(Wt%), more preferably 60-75 / 40-25
(Wt%), and often 65-75 / 35-25 (wt%).

In the combination of the above (IV), the ratio of the olefin polymer and the polyamide can be appropriately selected, but in order to enhance the transparency of the film, the olefin polymer / polyamide = 55 to 98/45. ~ 2 (wt%), preferably 60-85 / 40-15 (wt%),
More preferably, it is about 60 to 75/40 to 25 (% by weight), and often about 65 to 75/35 to 25 (% by weight).

In addition to the olefin polymer and polyamide,
For example, when a modified polyolefin such as a copolymer of an olefin, a styrene monomer, an α, β-ethylenically unsaturated carboxylic acid and / or an α, β-ethylenically unsaturated polycarboxylic acid or an acid anhydride thereof is added, , The easy tearability of the film is further improved.

The proportion of the modified polyolefin is, for example, 0.5 to 30 parts by weight, preferably 1 to 15 parts by weight, and more preferably 1 to 10 parts by weight based on 100 parts by weight of the resin composition of the olefin polymer and the polyamide. It is about part by weight.

In the above combination (V), the ratio of the olefin polymer and the polyester can be appropriately selected. For example, olefin polymer / polyester = 55.
~ 98 / 45-2 (wt%), preferably 60-85 /
40-15 (wt%), more preferably 60-75 /
40 to 25 (% by weight) and 65 to 75/35
It is often about 25 (% by weight).

Further, in the combination of the above (VI), the ratio of the olefin polymer and the vinyl polymer is, for example, olefin polymer / vinyl polymer = 55 to 98.
/ 45-2 (wt%), preferably 60-85 / 40-
15 (wt%), more preferably 60-75 / 40-
25 (% by weight), 65-75 / 35-25
It is often about (% by weight).

The film formed of the composition of (I) to (VI) has at least one of the film taking direction (MD direction) and the direction (TD direction) orthogonal to the taking direction, In particular, it can be easily torn in the MD direction. JIS K 6732 in one direction of film
The right-angled tear strength specified in -1953 is 150.
kg / cm or less, preferably 5 to 120 kg / cm, more preferably about 30 to 100 kg / cm, JIS
The Z-1702 elemental tear tear strength is 10 kg / cm or less, preferably 0.2 to 7.5 k.
g / cm, and more preferably about 0.5 to 7 kg / cm. When the right-angled tear strength is 30 kg / cm or more, the tearability is usually excellent and practical strength can be secured.

In particular, the films formed from the above compositions (I) and (II) can be easily torn in both the MD and TD directions of the film. This film has a right-angled tear strength of 150 kg / cm or less, preferably about 5 to 120 kg / cm, and an Elemendorf tear strength of 10 kg / cm or less, preferably 1 to 10 kg / in both MD and TD. cm
It is a degree.

Regarding the tear test of plastic films and sheets, as described above, JIS Z 170
2 is Elemendorff tear resistance test method, JIS K
6732 has a right-angled tear resistance test method and JIS
C 2318 specifies the edge tear resistance test method.

If the ratio MI _A / MI _B of the melt index MI _{A of the} resin forming the continuous phase and the melt index MI _{B of the} resin forming the dispersed phase is increased,
The uneven thickness of the film tends to decrease.

The film of the present invention may be unstretched,
It has a feature that it has a practical strength in both the film take-up direction and the direction orthogonal thereto, and is extremely easy to tear in the film take-up direction. Therefore, the film of the present invention can be torn in a straight line very easily without forming perforations or notches or undergoing a high-stretching treatment unlike the conventional film. Also,
There will be no beard on the cut. Further, since it is not necessary to form perforations, the contents can be stably retained in the initial packaging state for a long time by wrapping with a film to block the external atmosphere from the contents. Moreover,
Since it does not need to be stretched, wrinkles do not occur even if it is sealed by heat sealing or the like.

The film of the present invention may be adjusted in properties such as tear strength and breaking strength by uniaxial or biaxial stretching treatment, if necessary. The draw ratio in at least one direction can be appropriately selected within a range of, for example, about 1.1 to 2.5 times.

The easily tearable film may be covered with a coating layer such as a slipping layer or a gas barrier layer or a laminate layer as long as the tearability is not impaired. Further, the film may be subjected to surface treatment such as corona discharge treatment, flame treatment, ultrasonic treatment, and plasma treatment. Furthermore, the film is made of heat-resistant materials such as antioxidants and UV absorbers.
It may contain various additives such as a light resistance stabilizer, a plasticizer, an antistatic agent, a lubricant, a dye / pigment, and a filler.

The feature of the present invention is that even if the thickness of the film is small, the unevenness in thickness is remarkably suppressed and the surface smoothness is high. The thickness of the film is 5 to 50 μm, preferably 5 to 35 μm, more preferably 10 to 30 μm.
It is about 15 to 30 μm in many cases. Further, the thickness unevenness per 5 m in the film take-up direction (MD direction) is ± 100 with respect to the average thickness of the film.
%, Preferably within ± 50%, more preferably ±
Within 25%, especially within ± 20%.

Such an easily tearable film can be produced by an extrusion molding method using a T die. That is, a resin composition containing the thermoplastic resin as a main component is melted by an extrusion molding machine and extruded from a T die to form a film.

In the method of the present invention, the distance from the tip of the die lip to the point where the extruded molten resin comes into contact with the chill roll (cooling roll), that is, the air gap is 2 to 30 mm, preferably 5 to 25 mm, and more preferably. Is set in the range of about 10 to 20 mm. The air gap is often about 5 to 20 mm. If the air gap is less than 2 mm, the extruded molten resin accumulates between the tip of the die lip and the chill roll, and film breakage occurs, and deposits called eye crops generated at the tip of the die lip easily transfer to the film. In order to
It is difficult to obtain a good quality film. Also,
When the air gap exceeds 30 mm, streak-like thickness unevenness occurs in the film and the film take-up direction (M
A curved thickness unevenness may be periodically observed along the (D direction).

By setting the air gap in the above range, it is possible to remarkably reduce unevenness in the thickness of the film and obtain a film having high surface smoothness. Moreover, for example, even in the case of a thin film having a thickness of 50 μm or less, particularly 35 μm or less, the thickness unevenness per 5 m of the film taking direction (MD direction) can be suppressed to, for example, within ± 20%.

As shown in FIG. 1, the air gap A can be easily adjusted by the relative position of the die 1 and the chill roll 2, and the film-shaped or sheet-shaped molten resin composition from the die 1 is It is cooled while being taken up by the chill roll 2. The film 3 from the chill roll 2 is
In many cases, it is taken up by a take-up roll through a succeeding roll. Further, in the T-die forming method, the film cooled by the chill roll may be stretched, but a film having a smooth surface and high tearability can be obtained without stretching treatment even if the film is thin. Therefore, the productivity of the film and the like can be improved without performing the stretching treatment.

The temperature of the chill roll can be selected within a range that does not impair the cooling efficiency of the molten resin, and is, for example, 5 to 95 ° C, preferably 10 to 80 ° C in many cases. Further, the temperature of the chill roll is often controlled by passing water.

When the shear rate at the die lip portion during film extrusion molding is increased, the occurrence of film thickness unevenness tends to be suppressed. The shear rate can be increased by increasing the resin extrusion amount per unit time or by decreasing the lip clearance at the die tip. At this time, the resin discharge amount may be increased and the lip clearance may be reduced. When the resin discharge amount is increased, the film thickness can be adjusted by increasing the film take-up speed.

The film formation temperature is usually 300 ° C. or lower, for example, 1
50-300 degreeC, Preferably it is about 200-280 degreeC. In addition, the draw ratio during film forming (melt stretch ratio: ratio V2 of speed V1 at which molten resin is discharged from the die lip and speed V2 at which the formed film is wound up is V2 /
V1) can be appropriately selected in the range of about 1 to 70 (for example, about 5 to 70), preferably about 10 to 60, depending on the desired film thickness.

Two or more kinds of thermoplastic resins may be mixed and supplied to an extruder and melt-kneaded in the extruder to disperse the thermoplastic resin. The pellets obtained by previously melt-kneading the composition containing the above may be fed to the extruder. A mixture containing two or more thermoplastic resins as a main component is prepared by a conventional method, for example,
It can be prepared using a mixer such as a ribbon blender, a tumble mixer or a Henschel mixer. The pellets can be prepared using an open roll, Banbury mixer, single screw extruder, twin screw extruder, single screw reciprocating screw kneader, or the like.

The easily tearable film of the present invention can be used not only as a monolayer film but also as an easily tearable laminate by laminating it with a base material layer. That is, PTP
(Press Through Pack) By stacking an easily tearable film on an aluminum foil used as a lid material in packaging, etc., the lid material can be easily pressed by pressing the bottom of the container without increasing the burst strength of the lid material. Alternatively, the film can be ruptured and the contents such as tablets can be easily taken out. When an easily tearable film is laminated on paper such as kraft paper to form a sealed package, the tear resistance of the paper can be easily torn along the tearing direction without significantly increasing the tear resistance of the paper. Further, when it is used as a sealing film for a liquid outlet such as brick packaging, it can be easily broken through a straw or the like.

As the base material layer, an easily rupturable base material, for example, uniaxially or biaxially stretched composed of polymers such as olefin polymers such as polyethylene and polypropylene, polyvinyl chloride, polyesters such as polyethylene terephthalate, and styrene polymers. Film; glassine paper,
Paper such as imitation paper and white cardboard; metal foil such as aluminum.

Such a laminate (laminated film) can be obtained by, for example, a method of laminating an easily tearable film on the easily breakable base material layer using an adhesive, or a resin composition in the form of a film melt-extruded from a die. A conventional method such as a method of laminating the base material on the base material layer can be adopted. Also, when the base material layer is a heat-adhesive film such as an olefin-based polymer or styrene-based polymer, a method of heat-pressing an easily tearable film and fusing to such a base material layer is also adopted. it can.

The easily tearable film of the present invention is used for various applications such as pouch packaging and container packaging, for example, packaging bags, substrates for adhesive tapes, substrates for brick packaging, individual packaging for tablets and the like. It can be used for various purposes such as PTP (Press Through Pack) packaging base materials.

[0146]

EFFECT OF THE INVENTION The easily tearable film of the present invention has small thickness unevenness and high tearability even if it is thin. for that reason,
It has high surface smoothness and can be used as a high quality easy tear film.

According to the manufacturing method of the present invention, the thickness unevenness is reduced by the simple operation of adjusting the air gap.
A film with high tearability can be obtained. Further, it is possible to produce a film having a small thickness unevenness, a high surface smoothness and a high tearability, even if it is thin, without stretching, with high productivity.

[0148]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited by these examples.

The polymers used in Examples and Comparative Examples and their abbreviations are as follows.

Linear low density polyerylene (LLDPE):
Mitsui Petrochemical Co., Ltd., Ultzex 2028 Nylon 66 (Ny66): Ube Industries, Ltd., Ube Nylon 2020B Ethylene-vinyl acetate copolymer saponified product (EVOH):
Nippon Synthetic Chemical Co., Ltd., Soarnol DT2903 polypropylene (PP): Ube Industries, Ltd., Ube Polypro Y105J General polystyrene (GPPS): Nippon Steel Chemical Co., Ltd.,
Ethylene G12-55 Styrene-butadiene copolymer hydrogenated product (SEB
S): Asahi Kasei Co., Ltd., Tuftec H1061 Polybutylene terephthalate (PBT): Polyplastics Co., Ltd., Duranex 600FP Nylon 6 (Ny6): Ube Industries, Ltd., Ube Nylon 1030B Acid-modified adhesive polypropylene (M-PP): Mitsubishi Kasei Co., Ltd., Novatec AP 197P Nylon 12 (Ny12): Daicel Huls Co., Ltd.
Manufactured by Daiamide L2106F high impact polystyrene (HIPS): Sumitomo Chemical Co., Ltd.
Sumibrite M584 High Density Polyethylene (HDPE): Mitsubishi Kasei Co., Ltd.
Mitsubishi Polyethylene HD JV070S Examples 1-17, Comparative Examples 1-18 The resins shown in Table 1 were mixed at the compounding ratio shown in Table 1 by the tumbler method. The obtained resin composition was mixed with an extruder (65
mmφ, L / D = 32) and kneaded by heating, and extruded from the T-die method to prepare a film (thickness 20 μm).
The T-die used had a hanger manifold.
The air gap was adjusted by changing the relative position of the chill roll and die.

Die lip width 1500 mm Lip clearance 600 μm Molding temperature 240 to 280 ° C. Discharge rate 900 g / min The thickness of the center of the obtained film in the TD direction (the direction orthogonal to the film take-up direction) was measured in the MD direction (the film In the take-up direction), measurement was performed every 5 cm over 5 m. From the maximum thickness and the minimum thickness, the thickness unevenness (±
%) Was obtained, and the thickness unevenness of the film was evaluated according to the following criteria.

Thickness unevenness (±%) = {maximum thickness (μm) −
Minimum thickness (μm)} ÷ {Average thickness (μm)} ÷ 2 × 10
0 ◯: Thickness unevenness is ± 100% with respect to the average thickness of the film
Within: The thickness unevenness is out of the above range. The obtained film was torn in the MD direction with both hands, and the easy tearability of the film was evaluated according to the following criteria.

◯: Easy to tear ×: Not torn or no torn in the middle The results are shown in Tables 1 to 3. In Comparative Example 3, the film could not be formed because the adhered material at the tip of the die lip adhered to the film, and the film was immediately broken. As is clear from the table, the films of Examples are excellent in tearability, and even if they are thin, the thickness unevenness is extremely small.

[0154]

[Table 1]

[0155]

[Table 2]

[0156]

[Table 3]

[Brief description of drawings]

FIG. 1 is a schematic view showing an air gap in a film manufacturing apparatus.

[Explanation of symbols] A ... Air gap 1 ... Die 2 ... Chill roll

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location // B29K 23:00 25:00 77:00

Claims (13)

[Claims] 1. A film formed of a resin composition containing as a main component two or more kinds of thermoplastic resins having different repeating units, wherein the dispersed phase is dispersed in a continuous phase, the film having an average thickness of 5 to 50 μm. An easily tearable film in which the thickness unevenness per 5 m in the take-up direction is within ± 100% of the average thickness. 2. The compatibilizer of 0.1 to 30 parts by weight per 100 parts by weight of the total amount of the thermoplastic resin forming the continuous phase and the thermoplastic resin forming the dispersed phase is contained. Tearable film. 3. The easily tearable film according to claim 1, wherein the thermoplastic resin constituting the continuous phase is a polymer selected from an olefin polymer, a styrene polymer, a polyester and a polyamide. 4. The continuous phase is composed of an olefin polymer, and the dispersed phase is composed of at least one polymer selected from the group consisting of a styrene polymer, a polyester, a polyamide, a polycarbonate and a vinyl polymer. The easily tearable film according to claim 3. 5. The easily tearable film according to claim 4, which contains a styrene-based monomer-conjugated diene-based copolymer which may be hydrogenated or modified, or a modified polyolefin. 6. The continuous phase comprises a styrenic polymer,
The easily tearable film according to claim 3, wherein the dispersed phase is composed of at least one polymer selected from the group consisting of olefin polymers, polyesters and polyamides. 7. The continuous phase is composed of polyester, and the dispersed phase is composed of at least one polymer selected from the group consisting of an olefin polymer, a polycarbonate, a styrene polymer, an acrylic polymer and a polyamide. The easily tearable film according to claim 3. 8. The easily tearable film according to claim 1, which is formed of one of the following resin compositions. (I) Resin composition of 10 to 98% by weight of styrene polymer and 90 to 2% by weight of polyester, (II) Resin composition of 2 to 90% by weight of styrene polymer and 98 to 10% by weight of olefin polymer (III) Resin composition of 55 to 98% by weight of styrene polymer and 45 to 2% by weight of polyamide, (IV) Resin composition of 55 to 98% by weight of olefin polymer and 45 to 2% by weight of polyamide, V) Resin composition of 55 to 98% by weight of olefin polymer and 45 to 2% by weight of polyester, or (VI) Resin composition of 55 to 98% by weight of olefin polymer and 45 to 2% by weight of vinyl polymer. . 9. (II) Hydrogenated styrene-based monomer-conjugated diene-based copolymerization based on 100 parts by weight of a resin composition containing 2 to 90% by weight of a styrene-based polymer and 10 to 98% by weight of an olefin-based polymer. The easily tearable film according to claim 8, which is formed of a resin composition containing 0.5 to 25 parts by weight of the coalescence. 10. (IV) Olefin-based polymer 55-98
Resin composition 1 with 1% by weight and 45-2% by weight polyamide
The easily tearable film according to claim 8, which is formed of a resin composition containing 0.5 to 30 parts by weight of a modified polyolefin with respect to 00 parts by weight. 11. A film formed from one of the following resin compositions, having an average thickness of 5 to 35 μm and a film take-up direction of 5:
An easily tearable film whose thickness unevenness per m is within ± 25% of the average thickness. (I) 20-80 wt% styrene polymer and 80-20 wt% polyester resin composition, (II) 20-80 wt% styrene polymer and 80-20 wt% olefin polymer resin composition (III) Resin composition of 60 to 85% by weight of styrene polymer and 40 to 15% by weight of polyamide, (IV) Resin composition of 60 to 85% by weight of olefin polymer and 40 to 15% by weight of polyamide, V) Resin composition of 60 to 85% by weight of olefin polymer and 40 to 15% by weight of polyester, or (VI) Resin composition of 60 to 85% by weight of olefin polymer and 40 to 15% by weight of vinyl polymer. . 12. A method for producing an easily tearable film, which comprises extruding a resin composition containing two or more kinds of thermoplastic resins having different repeating units as main components from a T die under conditions of an air gap of 2 to 30 mm to form a film. . 13. A resin composition containing, as a main component, two or more kinds of thermoplastic resins which are incompatible with each other under the condition of a gap of 5 to 25 mm from a die lip to a cooling roll, without extruding from a T-die and stretching. , Average thickness 10-30
A method for producing an easily tearable film, wherein a film having a thickness unevenness of 5 μm per 5 m in the film pulling direction is within ± 20% of the average thickness.