JPH07299858A - Easy tearing film and production thereof - Google Patents

Abstract

PURPOSE:To obtain an easy tearing film free from thickness irregularity and high in surface smoothness and uniformity by subjecting a non-compatible resin compsn. to extrusion molding. CONSTITUTION:A resin compsn. containing a propylene type polymer (A) such as polypropylene and polyamide (B) derived from 6C lactam, aminocarboxylic acid, diamine or dicarboxylic acid such as nylon 6 in an (A)/(B) wt. ratio of 55/45-98/2 is subjected to extrusion molding. At this time, when the common logarithm value [log (MIA/MIB)] of the ratio of the melt indexes MIA, MIB (g/10min) of the components (A), (B) at 240 deg.C under load of 2.16kg is set to X and the shearing speed at a die lip is set to r(sec<-1>), the resin compsn. is subjected to extrusion molding under conditions such that r is r>=(115-168X) (a) at the time of X>=0 and r is r>=(115--96X) (b) at the time of X<0 without being stretched to obtain a film high in surface smoothness even when thickness is about 5-35mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an easily tearable film containing a propylene-based polymer and a polyamide as main components, which can be used as a packaging material having a high opening property, and a method for producing the film.

[0002]

2. Description of the Related Art As a film packaging material, various polymers such as polypropylene, polyethylene terephthalate, nylon, etc. are used, and the film is provided with a characteristic according to each polymer. However, since there is a limit to the properties that can be imparted by the polymer alone, a stretching treatment, a corona discharge treatment, and a composite by laminating and coating a plurality of polymer layers are being studied. For example, polypropylene or polyethylene is stretched to impart tearability to the film. However, when imparting tearability to the film by stretching, not only the stretching device and the work involved in the stretching operation are required, but also the cost becomes high, and the configuration of the stretching device (for example, stretching roll width) and its operability From the point of
When manufacturing films with different widths, it is necessary to change the configuration of the apparatus, etc., and thus the width of the film is limited. In addition, the stretched film is heat-sealed by heat sealing to generate wrinkles, which impairs the appearance.

On the other hand, if a technique of alloying a plurality of incompatible or low-affinity resins is used, the vapor barrier property, strength and heat resistance of the polymer alloy film are higher than those of a single polymer film. In many cases, properties such as tearability can be improved. Therefore, various studies have been made on the formation of composites using polymer alloys. For example, in Japanese Patent Laid-Open No. 1-153733,
A resin composition containing linear low-density polyethylene (LLDPE) and a thermoplastic resin that is incompatible with the linear low-density polyethylene and has a solubility coefficient of 9.0 or more in a specific ratio, A method of making a film that is easy to tear by hot melt extrusion is disclosed. Further, in JP-A-4-19137, two or more resin compositions which are incompatible with each other and have a large melting point difference, for example, a composition containing a high melting point nylon and a low melting point polyolefin is extruded and molded. It is disclosed to obtain a tearable laminated film by laminating with a base material.

The polymer alloy film as described above is
Although it has high tearability, when it is attempted to form a thin film, 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, resulting in a smooth surface of the film. And the uniformity is reduced. In particular, when a film having a practical thickness of 50 μm or less (for example, about 10 to 30 μm) 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 and thermoplastic resin is set to the former / the latter as described in JP-A-1-153733.
It is considered that the latter is set to 99/1 to 80/20 and the amount of the thermoplastic resin used is greatly limited. 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. Therefore, the application of the film using the polymer alloy is greatly limited.

The periodic thickness unevenness occurs in a long cycle of several seconds, and is not due to external factors such as mechanical vibrations caused by an extruder or a take-up machine, but the flow characteristics of the resin composition. It is presumed to be derived. That is, when a film is formed using a resin simple substance such as polypropylene, nylon, polyethylene, or polystyrene, even a thin film can be formed without any trouble. On the other hand, when trying to form a film by adding a small amount of an incompatible resin to the resin, the draft ratio (the take-up speed of the film and the extrusion of the resin at the die lip part) which was possible to form with the resin alone was formed. Periodic thickness unevenness also occurs in the speed ratio region. This cyclic thickness unevenness occurs when the draft ratio becomes large. For example, when an attempt is made to increase the draft ratio to increase the draft ratio to form a thin film of about 20 μm, the cyclic thickness unevenness occurs. It occurs remarkably. Then, in a film having periodic thickness unevenness, the thin portion has a thickness of about 10 μm and the thick portion has a thickness of 1 μm.
It will be more than 00 μm.

[0006]

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 an easily tearable film which has high surface smoothness and uniformity and in which wrinkles due to heat shrinkage are suppressed, and a method for producing the film.

Still another object of the present invention is to provide a method for producing a film having the above-mentioned excellent properties in a stable, efficient and highly productive manner.

[0009]

Means for Solving the Problems The inventors of the present invention have made extensive studies as a result of achieving the above object. As a result, when a composition containing a polypropylene-based polymer and a polyamide is formed into a film, the melt index of the components is As a result, they have found that the shear rate greatly affects the surface smoothness and film-forming stability of the film, and completed the present invention.

That is, in the method of the present invention, a resin composition containing (A) a propylene polymer and (B) a lactam having 6 carbon atoms, a polyamide derived from an aminocarboxylic acid, a diamine or a dicarboxylic acid as main components. Things,
A method for producing a film by extrusion from a die, comprising: melt index MI _A (g / 10) of a propylene-based polymer (A) at 240 ° C. and a load of 2.16 kg.
Min) and the melt index MI _B (g / 10 min) of polyamide (B) at 240 ° C. and a load of 2.16 kg, where X is the common logarithmic value [log (MI _A / MI _B )]. An easily tearable film is produced by extrusion-molding under the following conditions, where the shear rate at is r (sec ^-1 ).

(A) When X ≧ 0, r ≧ (115-168X) (b) When X <0, r ≧ (115-96X) Under the above temperature and load, a propylene polymer (A such as polypropylene) (A) ) Has a melt index MI _A of 0.5 to 35 (g / 10 minutes), and polyamide (B) such as nylon 6 has a melt index MI _B of 0.5 to 20.
It may be about (g / 10 minutes). The melt index ratio [MI _A / MI _B ] is 0.1 to 30.
It may be a degree. In the above-mentioned method, during extrusion molding, the film-shaped or sheet-shaped molten resin composition can be film-formed while taking in, for example, a draw ratio of about 5 to 70.

The above-mentioned (A) propylene polymer and (B)
The proportion of polyamide can be selected in a wide range, for example,
The former / latter may be about 55/45 to 98/2 (weight ratio). The resin composition may further contain a compatibilizer (C) such as a modified polyolefin.

The easily tearable film of the present invention thus obtained does not have thickness unevenness even if it is thin, and has high surface smoothness. That is, even in the case of a film having an average thickness of about 5 to 35 μm, the thickness unevenness per 5 m in the take-up direction of the film is within ± 100% of the average thickness. The easily tearable film may be laminated on a base material and used as an easily tearable laminated film.

In the present specification, MI _A is 24
0 ° C., a melt index of (A) propylene-based polymer as measured under a load 2.16 kg, MI _B is 2
The melt index of (B) a polyamide having 6 units of carbon is shown when measured at 40 ° C. and a load of 2.16 kg. X is the ratio of MI _A and MI _B (the former / the latter)
Represents the common logarithmic value of. That is, X = log (MI _A /
MI _B ).

Shear rate r (sec ^-1 ) at the die lip
Can be expressed by the following formula, where Q (cm ³ / min) is the flow rate (discharge amount) of the resin composition at the die lip, W (mm) is the die lip width, and H (mm) is the die lip opening.

R = [10 ² × Q] / [WH ² ] The present invention will be described in detail below.

The propylene polymer (A) includes homopolymers of propylene and copolymers of propylene with other olefins. Such olefins include ethylene; 1-butene, 4-methyl-1-butene, 1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1
Other olefins such as -decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene and the like having 4 to 20 carbon atoms: isobutene.

The propylene-based polymer may be a copolymer with another monomer copolymerizable with propylene.
Examples of the copolymerizable monomer include acrylic acid,
Ethylenically unsaturated carboxylic acids such as methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid, angelic acid;
Ethylenically unsaturated polycarboxylic acids such as maleic anhydride, citraconic anhydride, and itaconic anhydride, and acid anhydrides thereof;
Acrylic acid esters and methacrylic acid esters; ethylenically unsaturated carboxylic acid esters such as vinyl esters of carboxylic acids (eg vinyl acetate, vinyl propionate etc.); cyclic olefins such as norbornene, ethylidene norbornene and cyclopentadiene; and dienes etc. It is illustrated. The copolymerizable monomer may be used alone or in combination of two or more.

As the diene component, chain conjugated dienes such as 1,3-butadiene and 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.

The preferred propylene-based polymer is polypropylene; propylene and ethylene or C4-6.
Included are copolymers with some α-olefins. The propylene-based copolymer may be a block copolymer, but a preferable propylene-based copolymer includes a random copolymer. In the propylene-based copolymer,
The propylene content is 65% by weight or more. More preferable propylene-based polymers include polypropylene (for example, crystalline polypropylene such as isotactic polypropylene) and ethylene-based propylene.
A propylene copolymer (for example, a crystalline ethylene-propylene copolymer), particularly a crystalline polypropylene is preferable. When such a propylene-based polymer is combined with polyester, the easy tearability of the film can be enhanced. These propylene-based polymers can be used alone or in combination of two or more.

The molecular weight of the (A) propylene-based polymer is
For example, a weight average molecular weight of 1 × 10 ^{4 to} 100 × 10 ⁴ ,
It is preferably about 5 × 10 ⁴ to 50 × 10 ⁴ .

The C ₆ component constituting the (B) polyamide includes ε-caprolactam, 6-aminohexanoic acid, hexamethylenediamine, adipic acid and the like.
The C ₆ component that constitutes the (B) polyamide may be one type or two or more types. The (B) polyamide may contain a diamine other than the C ₆ component, a dicarboxylic acid, or an aminocarboxylic acid as a constituent unit. The polyamide also includes polyamide elastomer.

As the diamine forming the polyamide,
In the general formula _{H 2 N-L-NH 2} ( wherein, L is a divalent aliphatic group, a divalent alicyclic group or a divalent aromatic group, these groups have a substituent Which may be present) is used. As diamine, aliphatic diamine such as trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, octamethylenediamine; 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.

The dicarboxylic acid forming the polyamide is represented by the general formula HOOC-M-COOH (wherein M is a divalent aliphatic group, a divalent alicyclic group or a divalent aromatic group, The compound represented by these groups may have a substituent) and its acid anhydride are used. As the dicarboxylic acid, aromatic dicarboxylic acids such as phthalic acid, phthalic anhydride, isophthalic acid and terephthalic acid; cyclohexane-
Alicyclic dicarboxylic acids such as 1,4-dicarboxylic acid and cyclohexane-1,3-dicarboxylic acid; glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, octadecanedioic acid, etc. Aliphatic dicarboxylic acids; dimerized fatty acids and the like. 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. These dicarboxylic acids can be used alone or in combination of two or more.

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

As the lactam for forming polyamide,
Examples thereof include butyrolactam, valerolactam, caprolactam, capryllactam, enantolactam, undecanolactam, dodecaractam and the like. These lactams can also be used alone or in combination of two or more.

The preferred (B) polyamide is ε-
Nylon 6 derived from caprolactam or 6-aminohexanoic acid and copolymers with other monomers; Nylon 6
6, nylon 610, nylon 612, polyamide obtained from hexamethylene diamine and terephthalic acid and / or isophthalic acid, derived from hexamethylene diamine and dicarboxylic acid such as polyamide obtained from hexamethylene diamine, terephthalic acid and adipic acid Polyamide derived from adipic acid and diamine, such as nylon 46, polyamide obtained from adipic acid and metaxylylenediamine, and the like. These polyamides can be used alone or as a mixture.

More preferred polyamides include nylon 6, nylon 66, nylon 610, nylon 612 and the like, and copolymers containing these constituents, particularly nylon 6 (Ube nylon 1000 series manufactured by Ube Industries, Ltd.) and Copolymers containing the constituents are included.
The copolymer containing the constituent components of nylon 6 is a copolymer obtained from ε-caprolactam and / or 6-aminohexanoic acid, hexamethylenediamine and adipic acid (Ube nylon 5000 series, etc., manufactured by Ube Industries, Ltd.). ), A copolymer of ε-caprolactam and / or 6-aminohexanoic acid and ω-laurolactam and / or 12-aminododecanoic acid (Ube nylon 7000 series manufactured by Ube Industries, Ltd.) and the like.

The molecular weight of the (B) polyamide is, for example, about 1 × 10 ^{4 to} 100 × 10 ⁴ , preferably about 2 × 10 ⁴ to 50 × 10 ⁴ , the weight average molecular weight.

In the present invention, the melt index MI of (A) propylene-based polymer and (B) polyamide
_A and MI _B, depending on the type and combination can be selected appropriately, not particularly limited as long as it is possible film molding.
(A) Propylene polymer melt index [M
In the case of polypropylene, I _A ] is, for example, 0.5 g /
It is 10 minutes or more, preferably 0.5 to 35 g / 10 minutes, more preferably 1 to 25 g / 10 minutes, and the melt index [MI _B ] of the (B) polyamide is nylon 6
In the case of, for example, 0.5 to 20 g / 10 minutes, preferably 0.7 to 15 g / 10 minutes, and more preferably 1 to 10 g /
It takes about 10 minutes. When a propylene-based polymer such as polypropylene and a polyamide such as nylon 6 are combined and the melt index of the component (A) and / or the component (B) is out of the above range, film moldability, film-forming stability and film are obtained. May decrease in strength.

[0031] (A) a propylene and the melt index MI _A polymer (B) ratio of the melt index MI _B polyamide (the former / the latter) is not particularly limited,
Usually, [MI _A / MI _B ] is 0.1 to 30, preferably 0.3 to 20, and more preferably about 0.5 to 10. If the ratio [MI _A / MI _B ] is less than 0.1, the processability of the film may be reduced, and if it exceeds 30, the melt viscosity of the propylene-based polymer may be small and the tearability of the film may be reduced. The melt index ratio MI
_A / MI _B is 1 or more, preferably 1.1 to 30, more preferably 1.5 to 20, especially it is about 2 to 10,
The film formation stability during film formation can be improved.

The ratio (composition ratio) of the (A) propylene-based polymer and the (B) polyamide in the resin composition is not particularly limited and can be selected within a range in which tearability can be imparted. For example, (former / latter) = 55. / 45 to 98/2, preferably 60/40 to 85/15, more preferably 60/40
~ 75/25, more preferably 65 / 35-75 / 2
It is about 5 (weight ratio). In the film obtained by using such a resin composition, the dispersed phase of the (B) polyamide is often dispersed in the continuous phase of the (A) propylene-based polymer, and thus the stretching treatment is not required. Excellent in tearability. If the proportion of the propylene-based polymer is less than 55% by weight, the tearability tends to be low and it is difficult to tear linearly, and if it exceeds 98% by weight, the tearability tends to be low.

The above-mentioned (A) propylene polymer and (B)
Incompatible with polyamide. Therefore, the strength of the film, peeling at the surface layer of the film, or the appearance may be impaired. In such a case, it is effective to add the compatibilizing agent (C) to the resin composition.

The compatibilizing agent (C) is not particularly limited as long as it is a compound having compatibility or affinity with the incompatible polymer. The compatibilizing agent includes, for example, a modified polyolefin having a functional group introduced therein. Functional groups introduced into the modified polyolefin include, for example, carboxyl groups, alkoxycarbonyl groups, epoxy groups such as glycidyl groups, and the like. A plurality of these functional groups may be combined and introduced into the polyolefin. These modified polyolefins can be used alone or in combination of two or more.

As the olefin component in the modified polyolefin, for example, 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
-Alpha olefins having 2 to 20 carbon atoms such as tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene can be used. Preferred olefins include C2-C4 α-olefins such as ethylene and propylene, and particularly ethylene and propylene.

The carboxyl group is, for example, an ethylenically unsaturated carboxylic acid such as acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, mesaconic acid, angelic acid; anhydrous. It can be introduced by polymerizing an ethylenically unsaturated polyvalent carboxylic acid such as maleic acid, citraconic acid anhydride or itaconic acid anhydride and its acid anhydride into an olefin or a polyolefin. Alkoxycarbonyl groups are vinyl esters such as vinyl acetate and vinyl propionate,
It can be introduced by polymerizing a (meth) acrylic acid ester or the like. The epoxy group can be introduced by polymerizing a polymerizable unsaturated compound having an epoxy group such as glycidyl (meth) acrylate.

Examples of the modified polyolefin include carboxy modified polyolefin, epoxy modified polyolefin, carboxy and epoxy modified polyolefin and the like. Specifically, the carboxy-modified polyolefin includes, for example, an ethylene-maleic anhydride copolymer [eg, Admer NF series (trade name) manufactured by Mitsui Petrochemical Co., Ltd.] and the like. Examples of the epoxy-modified polyolefin include ethylene-glycidyl (meth) acrylate copolymer [for example, manufactured by Sumitomo Chemical Co., Ltd.,
Bondfast E (trade name)], glycidyl-modified polyethylene [for example, Lexpearl J-3700 manufactured by Nippon Petrochemical Co., Ltd.] and the like are included. Further, epoxy- and carboxy-modified polyolefins include, for example, ethylene-
(Meth) acrylic ester-maleic anhydride-modified polyethylene such as ethyl (meth) acrylate-maleic anhydride copolymer [eg, N-Polymer A1600 (trade name) manufactured by Nippon Petrochemical Co., Ltd., Sumitomo Chemical ( Manufactured by K.K., Bondine AX8060 (trade name), etc.] and the like are included.

The modified polyolefin may be a copolymer with another copolymerization component, for example, a vinyl monomer such as a styrene monomer. Such modified polyolefins include, for example, copolymers of olefins, styrene monomers such as styrene, and ethylenically unsaturated carboxylic acids and / or ethylenically unsaturated polycarboxylic acids or acid anhydrides thereof [eg, , Mitsubishi Kasei Co., Novatec AP (trade name), Mitsubishi Yuka Co., Ltd., Modic (trade name), etc.] and the like.

Preferred modified polyolefins include carboxy modified polyolefins, especially carboxy modified polyolefins. Carboxy-modified polyolefins also include epoxy and carboxy-modified polyolefins, copolymers of olefins, styrenic monomers, ethylenically unsaturated carboxylic acids and / or ethylenically unsaturated polycarboxylic acids, or acid anhydrides thereof.

The amount of the compatibilizing agent (C) used is within a range capable of improving characteristics such as the appearance of the film, peeling of the surface layer of the film, and puncture strength of the film, for example, (A) propylene polymer and (B) polyamide. 0.1 to 30 parts by weight, preferably 0.5 to 20 parts by weight, and more preferably 1 to 10 parts by weight, based on 100 parts by weight of
In most cases, about 7.5 parts by weight is used. If the amount of the compatibilizer used is less than 0.1 parts by weight, the moldability may be lowered, and the above properties may not be improved so much, and if it exceeds 30 parts by weight, the amount becomes excessive, which is not economical.

The above-mentioned resin composition for obtaining the easily tearable film may contain other thermoplastic resins and various additives such as heat resistance and light resistance stability such as antioxidants and ultraviolet absorbers, if necessary. It may contain agents, plasticizers, antistatic agents, lubricants, dyes and pigments, fillers and the like.

The easily tearable film of the present invention is characterized by high surface smoothness and uniformity even if the film is thin.
The thickness of the film is not particularly limited and is, for example, 5 to 10
Although it can be selected in the range of 0 μm, preferably about 8 to 50 μm, the present invention is suitably applied to a thin film, for example, a film having an average thickness of 5 to 35 μm, preferably 10 to 30 μm, more preferably 15 to 30 μm. To be done. In addition, the thickness unevenness of the film is within ± 100%, preferably within ± 50%, more preferably within ± 30%, and more preferably within ± 20% with respect to the average thickness per 5 m in the film take-up direction. In many cases.

The easily tearable film of the present invention may be coated 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. In addition, the film, corona discharge treatment, flame treatment, ultrasonic treatment,
Surface treatment such as plasma treatment may be performed. If necessary, the tear strength, breaking strength, and other characteristics of the easily tearable film may be adjusted by uniaxial or biaxial stretching treatment within a range that does not impair the tearability. 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 of the present invention can be used not only as a monolayer film but also as an easily tearable laminate (easily tearable laminated film) by laminating it with a base material layer. That is, when an easily tearable film is laminated on an aluminum foil used as a lid material in PTP (Press Through Pack) packaging, etc., it is easy to press the bottom of the container without increasing the burst strength of the lid material. The contents such as tablets can be easily taken out by bursting the lid material or the film. 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, an olefin polymer such as polyethylene or polypropylene, a polyester such as polyvinyl chloride or polyethylene terephthalate, or a uniaxially or biaxially stretched polymer such as a styrene polymer. Film; glassine paper,
Paper such as imitation paper and white cardboard; metal foil such as aluminum.

Such a laminate is obtained, for example, by laminating the easily breakable base material layer and the easily tearable film by a conventional method such as adhesion, extrusion lamination, thermocompression bonding (thermal adhesion). You can

The film of the present invention is easy to tear in the take-up direction of the film without forming perforations or notches or highly stretched and can be torn linearly very easily. That is, when tearing by hand in one direction, not only the initial tear resistance (tearing resistance) but also the subsequent tear propagation resistance are extremely small, and whiskers do not occur at the cut. Therefore, although it is easy to tear straight and neat in a specific direction, it is hard to tear in other directions. Further, not only the surface smoothness and uniformity are high, but also the heat shrinkage and the generation of wrinkles due to heat sealing and the like can be suppressed, so that it can be suitably used for pouch packaging and container packaging.

The easily tearable film of the present invention can be produced by extruding the resin composition by a conventional method such as a T-die molding method or an inflation molding method.

The feature of the present invention is to obtain a film by extruding a molten resin composition from a die at a specific shear rate in association with the melt index of the above-mentioned (A) propylene polymer and (B) polyamide. is there. That is, the melt index MI _A (g / 10) of the propylene-based polymer (A) at 240 ° C. and a load of 2.16 kg.
Min) and the melt index MI _B (g / 10 min) of polyamide (B) at 240 ° C. and a load of 2.16 kg, where X is the common logarithmic value [log (MI _A / MI _B )]. A film is obtained by extrusion molding under the following conditions, where r (sec ^-1 ) is the shear rate at.

(1) When X ≧ 0, r ≧ (115-168X) (2) When X <0, r ≧ (115-96X) It is preferable to obtain a film having high surface smoothness and high quality. The minimum shear rate (reference value) r is as follows.

(A) When X ≧ 0, r ≧ (120-168X), preferably (120-168X) ≦ r ≦ (365-168X), more preferably (125-168X) ≦ r ≦ (315- 168X), especially (130-168X) ≦ r ≦ (265-168X) in many cases.

(B) When X <0, r ≧ (120-96X), preferably (120-96X) ≦ r ≦ (365-96X), more preferably (125-96X) ≦ r ≦ (315- 96X), especially (130-96X) ≦ r ≦ (265-96X) in many cases.

When extruded at the shear rate in relation to the melt index of the components (A) and (B),
It is possible to stably obtain a film which has little unevenness in thickness regardless of the thickness and has not only tearability but also high surface smoothness and uniformity. Particularly, a practical thickness of 50 μm
Hereinafter, for example, even if the film has a thickness of about 10 to 30 μm, it is possible to form an easily tearable film with high surface smoothness and uniformity without periodic thickness unevenness or perforation.

The film forming temperature can be selected according to the kinds of the components (A) and (B), and is, for example, 300 ° C. or lower, preferably 170 to 270 ° C., more preferably 200 to 26.
It is about 0 ° C.

In forming the film, the molten film or sheet resin composition discharged from the die is
Even if it is cooled and formed into a film without stretching, high tearability is exhibited. Therefore, not only a stretching device is not required, but also the time, work and cost required for the stretching process can be saved and the productivity of the film can be remarkably improved.
Moreover, since the film width is not restricted by the stretching process, a wide film can be easily obtained. Furthermore, since the stretching treatment is unnecessary, the obtained film is not heat-shrinked even if it is subjected to heat sealing. Therefore, even when subjected to heat sealing, the appearance is impaired in pouch packaging for storing contents in bag-shaped packaging materials, container packaging for sealing the opening of the container for storing contents with a lid material, etc. There is no.

In the T-die molding method, a resin composition containing propylene-based polymer (A) and polyamide (B) as main components is melted by an extrusion molding machine and extruded from a T-die and drawn, while being stretched. The film may be formed without doing. In the T-die molding method, the draw ratio (the ratio V1 / V2 of the speed V1 at which the molten resin is discharged from the die lip and the winding speed V2 of the molding film) is, for example, 5 to 70, preferably 10 to 60, More preferably, it is often 20 to 50, and the film is often formed while taking it off.

In the inflation molding method, when the molten resin composition is extruded from a circular die, it may be formed into a film by buffing it while taking it out. In the inflation molding method, the ratio (deformation ratio) of the draw ratio (melt expansion ratio) V to the blow ratio (expansion ratio) D (deformation ratio) V / D = 0.5 to 8, preferably 0.5 to 5, and more preferably 0. The draw ratio and the blow ratio are, for example, 1 to 5
20 and a blow ratio of about 1-10. The "draw ratio" and the "blow ratio" for a resin melt melted at a temperature higher than the melting point are distinguished from "stretching" performed at a temperature equal to or lower than the melting point of the polymer.

The preferred method uses the T-die molding method. In film forming, the distance from die to chill roll (cooling roll) (ie air gap)
By adjusting, it is possible to obtain a film having high surface smoothness.

[0059] In film forming, shown as melt index MI _A propylene-based polymer is higher than the melt index MI _B polyamide (i.e. low melt viscosity), the tendency of the moldability of the film is stabilized. However, even when the MI _B in the polyamide than MI _A propylene-based polymer is large, in the present invention, by increasing the shear rate, it can improve the uniformity and surface smoothness of the film. In order to increase the shear rate, the discharge amount of the resin may be increased, or if the discharge amount is the same, the width of the die lip and / or the die lip opening may be reduced.

The resin composition containing the components (A) and (B) may be prepared by mixing the components and supplying the mixture to an extruder and melt-kneading in the extruder to disperse the thermoplastic resin.
The composition containing the thermoplastic resin as a main component may be melt-kneaded in advance, and the resulting pellets may be supplied to an extruder. The mixture containing the above components can be prepared by a conventional method, for example, 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 and the laminated film using the same are a bag for packaging, a substrate for adhesive tape,
It can be used for various purposes such as a base material for brick packaging and a base material for PTP (Press Through Pack) packaging used for individual packaging of tablets and the like.

[0062]

EFFECTS OF THE INVENTION The easily tearable film of the present invention has small thickness unevenness even if it is thin, and has high surface smoothness and uniformity.

In the method of the present invention, the shear rate is adjusted in relation to the melt index of the (A) propylene-based polymer and (B) the polyamide having 6 carbon units, so that the uneven thickness can be obtained even if the thickness is thin. It is possible to produce an easily tearable film having a small size and excellent tearability. In addition, the obtained film has high surface smoothness and uniformity, and since it does not need to be stretched, it is possible to suppress the generation of wrinkles due to heat shrinkage. Furthermore, since the film can be formed while being taken up without stretching, a film having the above-mentioned excellent properties can be produced stably and efficiently with high productivity.

[0064]

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. The MI is a melt index (unit: 240 ° C., load 2.16 kg).
g / 10 minutes).

[Polypropylene (PP)] Polypropylene (PP-1): Ube Poly Pro B101H [MI: 2] Polypropylene (PP-2): Ube Poly Pro YK121 [MI: 4] ] Polypropylene (PP-3): Ube Industries, Ltd., Ube Polypro Y105J [MI: 6] Polypropylene (PP-4): Ube Industries, Ltd., Ube Polypro FM101A [MI: 13] Polypropylene (PP-5): Ube Polysan S115M [MI: 22] [Nylon 6 (Ny6)] Nylon 6: Ube Industries 1030B [MI:
4] [Olefin-styrene-based monomer-unsaturated carboxylic acid copolymer (C-1)] Mitsubishi Kasei Co., Ltd., Novatec AP 197P Examples 1 to 7, Comparative Examples 1 to 5 The resin composition obtained by mixing with a tumbler mixer at 65 mmφ extruder (L /
D = 32), and a film (average thickness 20 μm) was obtained by the T-die method under the following conditions. A T-die provided with a coat hanger type manifold was used. Further, the shear rate at the die lip was adjusted by changing the screw rotation speed and adjusting the discharge amount of the resin composition.

[Resin Composition (Weight Ratio)] Example 1, Comparative Example 1 [PP-1 / Ny6] = 70/30 Example 2, Comparative Example 2 [PP-2 / Ny6] = 70/30 Example 3 Comparative Example 3 [PP-3 / Ny6] = 70/30 Example 4 [PP-3 / Ny6 / C-1] = 70/30/5 Example 5, Comparative Example 4 [PP-4 / Ny6] = 70/30 Example 6, Comparative Example 5 [PP-4 / Ny6 / C-1] = 70/30/5 Example 7 [PP-5 / Ny6] = 70/30 [Molding conditions] Cylinder and die temperature 240 ° C T die die lip width 1500 mm Die lip opening 600 µm Draw ratio Approximately 30 In the center part of the TD direction (direction orthogonal to the film take-up direction) of the films obtained in Examples 1 to 7 and Comparative Examples 1 to 5 above. Thickness in MD direction (film take-up direction)
In addition, the measurement was performed at a pitch of 5 cm over 5 m, and the difference between the maximum value and the minimum value was evaluated by the following formula.

Δt = [maximum thickness (μm) −minimum thickness (μm)] Further, the thickness unevenness (±%) is calculated from the maximum thickness and the minimum thickness by the following formula, and the surface smoothness of the film is calculated according to the following criteria. The sex was evaluated.

Thickness unevenness (±%) = [Δt / (average thickness (μm))] / 2 × 100 ○: Thickness unevenness is ± 100% with respect to the average thickness of the film.
Within x: Thickness unevenness exceeds the above range. The results are shown in the table, and the relationship between the MD direction distance (cm) and the film thickness (μm) in Example 2 is shown in FIG. 1. In the table, the numbers in the columns of MI _A and MI _B represent the melt indexes (g / 10 minutes) of polypropylene and nylon 6 measured under the conditions of 240 ° C. and a load of 2.16 kg, respectively, and X is log ( MI _A / M
I _B ). When X ≧ 0 (115-168X)
And the minimum shear rate represented by (115-96X) when X <0 is represented by Y _s , and the shear rate at the die lip is represented by r (sec ⁻¹ ).

[0070]

[Table 1] As is clear from the table and FIG. 1, in each of the films of Comparative Examples, periodic thickness unevenness occurs in the range of ± 200% to ± 375%, and the surface smoothness is remarkably inferior. The thickness unevenness of each of the films obtained in (2) is within ± 20%, and the surface smoothness and uniformity are high. Each of the films of the examples could be easily torn linearly in the film-drawing direction.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the distance (cm) in the MD direction and the thickness (μm) of the film obtained in Example 2.

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Claims (10)

[Claims] 1. A propylene-based polymer (A) and (B)
A method for producing a film by extruding a resin composition containing a polyamide derived from a lactam having 6 carbon atoms, an aminocarboxylic acid, a diamine or a dicarboxylic acid as a main component from a die at 240 ° C. and a load. 2.
The ratio of the melt index MI _A (g / 10 min) of the propylene-based polymer (A) at 16 kg and the melt index MI _B (g / 10 min) of the polyamide (B) at 240 ° C. and a load of 2.16 kg. Common logarithm [log
(MI _A / MI _B )] is X and the shear rate at the die lip is r (sec ⁻¹ ), a method for producing an easily tearable film which is extrusion-molded under the following conditions. (A) When X ≧ 0, r ≧ (115-168X) (b) When X <0, r ≧ (115-96X) Wherein the melt index MI _A propylene-based polymer is 0.5 to 35 (g / 10 min), polyamide melt index MI _B is 0.5 to 20 (g
/ 10 minutes) and the ratio of MI _A and MI _B [MI _A / MI
_B ] is 0.1-30, The manufacturing method of the easily tearable film of Claim 1. 3. A resin composition containing (A) a propylene-based polymer and (B) a polyamide in a ratio of former / latter = 55/45 to 98/2 (weight ratio) is molded. A method for producing a tearable film. 4. The method for producing an easily tearable film according to claim 1, wherein the resin composition further contains a compatibilizing agent (C). 5. The method for producing an easily tearable film according to claim 4, wherein the compatibilizing agent (C) is a modified polyolefin. 6. (A) a propylene-based polymer and (B)
Carboxy-modified polyolefin 0.1 to 30 as a compatibilizer (C) with respect to 100 parts by weight of the total amount of polyamide.
The method for producing an easily tearable film according to claim 1, wherein a resin composition containing parts by weight is molded. 7. The method for producing an easily tearable film according to claim 1, wherein extrusion molding is performed at a draw ratio of 5 to 70. 8. A mixture of (A) polypropylene and (B) nylon 6 in a ratio of former / latter = 60/40 to 85/15 (weight ratio) at 240 ° C. and a load of 2.16 kg (A). ) Polypropylene melt index MI
_A is 1 to 25 (g / 10 min), a (B) a melt index MI _B is from 0.7 to 15 Nylon 6 (g / 10 min), and the ratio of the melt index is 0.3 to 20
A method of producing a film by extruding a resin composition which is a die from a die, wherein X is a common logarithmic value [log (MI _A / MI _B )] of the melt index ratio,
A method for producing an easily tearable film, which is extruded under the following conditions without stretching when the shear rate at the die lip is r (sec ^-1 ). (A) When X ≧ 0, (120-168X) ≦ r ≦ (3
65-168X) (b) When X <0, (120-96X) ≦ r ≦ (36
5-96X) 9. The easily tearable film obtained by the production method according to claim 1, wherein the average thickness is 5 to 35 μm, and the thickness unevenness per 5 m in the take-up direction of the film is
An easily tearable film having an average thickness within ± 100%. 10. An easily tearable laminate in which a film is laminated on a base material having an average thickness of 10 to 30 μm and a thickness unevenness per 5 m of the film in the take-up direction is within ± 50% of the average thickness. the film.