JP2005146207A - Stretched film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linearly cuttable film that has excellent transparency in addition to excellent gas barrier properties. <P>SOLUTION: The polyamide resin composition (E) that is composed of (C) 10 to 40 mass% of polyamide resin composition including (A) 92 to 99 mass% of polyamide resin prepared by polycondensation reaction between the diamine components including ≥ 70 mole% of m-xylylenediamine and the dicarboxylic acid components including ≥70 mole% of α,ω-straight chain aliphatic dicarboxylic acids, (B) 8 to 1 mass% of smectite that is treated with an organic swelling agent and (D) 90 to 60 mass% of an aliphatic polyamide resin. The resultant polyamide resin composition (E) is biaxially oriented to give a linearily cuttable stretched film. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a stretched film having linear cut properties.

  Conventionally, when tearing by hand to take out the contents in plastic sachet packaging, a biaxially stretched film mixed with different resins has been used to make it easier to take out the contents by cutting the bag straight. Has been used. For long-term storage of the contents, polyamide resins having better oxygen barrier properties than olefin resins such as polyethylene and polypropylene have been used, and olefin resin layers laminated with a polyamide resin layer have been used. I came.

  Among these polyamide resins, polyamide MXD6 (hereinafter sometimes referred to as “nylon MXD6” or “NMXD6”) obtained from metaxylylenediamine and adipic acid has a gas barrier property such as oxygen even under high humidity. Excellent, content is not easily oxidized or denatured, and because heat stability is good, when forming a laminate into a container, there is little generation of harmful decomposition products even when heated for thermal bonding It is known that it has the characteristics. For this reason, a straight-cut film made of a laminate of a biaxially stretched resin composed of nylon MXD6 and an aliphatic polyamide and a polyolefin layer has been proposed (see, for example, Patent Documents 1 to 5).

However, if the content of nylon MXD6 is increased in order to increase the barrier property in this linear cut film, there is a problem that the linear cut performance is lowered. As a method for improving the gas barrier property, a method of mixing an aliphatic polyamide with improved gas barrier property and nylon MXD6 can be considered. When nylon 6 to which a layered silicate is added is used as the aliphatic polyamide having improved gas barrier properties, the gas barrier properties are improved, but there is a problem that transparency is deteriorated.
A straight-cut film having excellent transparency and gas barrier properties has not yet been provided.
Japanese Patent No. 2617657 Japanese Patent No. 2617659 Japanese Patent No. 2665435 Japanese Patent Laid-Open No. 5-220837 JP 9-157410 A

  The present invention is intended to provide a linear cut film having excellent transparency and gas barrier properties.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have obtained a resin obtained by melt-kneading a polyamide resin having a specific property and smectite treated with an organic swelling agent at a specific ratio and an aliphatic polyamide resin. It has been found that a linear cut stretched film that solves the above-mentioned problems can be obtained by biaxially stretching a resin composition comprising the above, and the present invention has been completed.

  That is, the present invention polycondenses a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid component containing 70 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. The polyamide resin composition (C) 10 containing the smectite (smectite (B)) treated with the organic swelling agent in the range of 8 to 1% by mass in the range of 92 to 99% by mass of the obtained polyamide resin (A). It is an invention relating to a stretched film having linear cut properties obtained by biaxially stretching a polyamide resin composition (E) composed of 40% by mass and an aliphatic polyamide resin (D) 90-60% by mass.

  In the stretched film of the present invention, smectite is dispersed in the polyamide resin (A), whereby the barrier property can be improved while maintaining the linear cut property and transparency. That is, the stretched film of the present invention is characterized by excellent barrier properties, linear cut properties and transparency, and has high industrial value.

  The polyamide resin (A) used in the present invention includes a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid containing 70 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms. It is obtained by polycondensation with an acid component. The polyamide obtained by using such raw materials is excellent in properties such as barrier properties against gaseous substances such as oxygen and carbon dioxide when finally used as a barrier layer of a multilayer structure. Of these, polyamide MXD6 (hereinafter sometimes referred to as MX nylon) obtained by polycondensation of metaxylylenediamine and adipic acid is particularly preferable because of its excellent barrier property against gaseous substances such as oxygen and carbon dioxide.

  In the present invention, as other diamines other than metaxylylenediamine, tetramethylenediamine, pentamethylenediamine, 2-methylpentanediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, dodeca Aliphatic diamines such as methylenediamine, 2,2,4-trimethyl-hexamethylenediamine, 2,4,4-trimethylhexamethylenediamine; 1,3-bis (aminomethyl) cyclohexane, 1,4-bis (aminomethyl) ) Cyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, 2,2-bis (4-aminocyclohexyl) propane, bis (aminomethyl) decalin, bi Examples include alicyclic diamines such as (aminomethyl) tricyclodecane; diamines having an aromatic ring such as bis (4-aminophenyl) ether, paraphenylenediamine, paraxylylenediamine, and bis (aminomethyl) naphthalene. be able to.

  In the present invention, examples of the α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms include succinic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, adipic acid, sebacic acid, undecanedioic acid, and dodecanediic acid. Aliphatic dicarboxylic acids such as acids can be exemplified, and among these, adipic acid is preferred.

  As the dicarboxylic acid other than the α, ω-linear aliphatic dicarboxylic acid, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid can be used within a range not exceeding 30 mol%.

  The polyamide resin (A) has a relative viscosity (96 g sulfuric acid solution of 1 g / dl, 25 ° C.) of 2.4 to 3.9, preferably 2.5 to 3.7, more preferably 2.6 to 3. .7 can be used. When the relative viscosity is less than 2.4, the dispersibility of the smectite (B) in the polyamide resin composition (C) is insufficient, so that a sufficient gas barrier property improving effect cannot be obtained. Those having a relative viscosity of more than 3.9 are difficult to produce. In addition, by setting the relative viscosity to 2.4 to 3.9 in particular, the dispersibility of smectite (B) is improved, and the width of the film or sheet obtained because there is little neck-in during T-die extrusion. This makes it easy to adjust the width and size.

  The smectite (B) used in the present invention uses a polymer compound or an organic compound-based swelling agent as an organic swelling agent, and is previously brought into contact with the layered silicate (smectite) to form an interlayer of the layered silicate. Is an extension of The amount of the organic swelling agent used is preferably such that the content of the organic swelling agent in the smectite (B) is 20 to 50% by mass.

  The smectite used in the present invention is a 2-octahedral or 3-octahedral layered silicate having a charge density of 0.25 to 0.6. Examples of the 2-octahedral type include montmorillonite and beidellite. The 3-octahedron type includes hectorite, saponite and the like. Among these, montmorillonite is preferable.

  Although a quaternary ammonium salt can be preferably used as the organic swelling agent, preferably a quaternary ammonium salt having at least one alkyl group having 12 or more carbon atoms is used.

  Specific examples of organic swelling agents include trimethyldodecyl ammonium salt, trimethyl tetradecyl ammonium salt, trimethyl hexadecyl ammonium salt, trimethyl octadecyl ammonium salt, trimethyl eicosanyl ammonium salt, trimethyl octadecenyl ammonium salt, trimethyl octadecadi Trimethylalkylammonium salts such as enylammonium salts; triethylalkylammonium salts such as triethyldodecylammonium salts, triethyltetradecylammonium salts, triethylhexadecylammonium salts, triethyloctadecylammonium salts; tributyldodecylammonium salts, tributyltetradecylammonium salts, tributyl Hexadecyl ammonium salt, tributyl octadecyl ammonium salt, etc. Tributyl alkyl ammonium salt; dimethyl didodecyl ammonium salt, dimethyl ditetradecyl ammonium salt, dimethyl dihexadecyl ammonium salt, dimethyl dioctadecyl ammonium salt, dimethyl dioctadecenyl ammonium salt, dimethyl dioctadecenyl ammonium salt, dimethyl Dimethyldialkylammonium salts such as ditallowammonium salts; diethyldialkylammonium salts such as diethyldidodecylammonium salt, diethylditetradecylammonium salt, diethyldihexadecylammonium salt, diethyldioctadecylammonium salt; dibutyldidodecylammonium salt, dibutyl Ditetradecyl ammonium salt, dibutyl dihexadecyl ammonium salt, dibutyl dioctadecyl ammonium salt Dibutyldialkylammonium salt; methylbenzyldialkylammonium salt such as methylbenzyldihexadecylammonium salt; dibenzylalkylammonium salt such as dibenzyldihexadecylammonium salt; tridodecylmethylammonium salt, tritetradecylmethylammonium salt, etc. Trialkylmethylammonium salt; trialkylethylammonium salt such as tridodecylethylammonium salt; trialkylbutylammonium salt such as tridodecylbutylammonium salt; monomethyl octadecylammonium salt; 4-amino-n-butyric acid, 6-amino- n-caproic acid, 8-aminocaprylic acid, 10-aminodecanoic acid, 12-aminododecanoic acid, 14-aminotetradecanoic acid, 16-aminohexadecanoic acid, 18-a Examples thereof include acids such as minooctadecanoic acid and salts thereof. Among them, trimethyldodecyl ammonium salt, trimethyl tetradecyl ammonium salt, trimethyl hexadecyl ammonium salt, trimethyl octadecyl ammonium salt, dimethyl didodecyl ammonium salt, dimethyl ditetradecyl ammonium salt, dimethyl dihexadecyl ammonium salt, dimethyl dioctadecyl ammonium salt, dimethyl Quaternary ammonium salts such as ditallow ammonium salts are preferred. These quaternary ammonium salts and the like can be used alone or as a mixture of a plurality of types.

  The blending ratio of smectite (B) in the present invention is preferably 1-8% by mass (polyamide resin (A) is 99-92% by mass) in the polyamide resin composition (C). More preferably, the content is 5 to 5% by mass. When the blending ratio of smectite (B) is 1% by mass or more, an effect of improving gas barrier properties appears. Even if it is increased from the above 8% by mass, an improvement in gas barrier properties corresponding to that cannot be expected.

  The smectite (B) contained in the polyamide resin composition (C) needs to be uniformly finely dispersed without locally agglomerating. Here, the uniform dispersion means that the layered silicate is separated into a flat plate shape in the polyamide, and 50% or more of them have an interlayer distance of 5 nm or more. This interlayer distance is the distance between the centers of gravity of the flat objects. The larger the distance, the better the dispersion state, and finally, after mixing the aliphatic polyamide resin (D), the film obtained by biaxial stretching improves the barrier property against gaseous substances such as oxygen and carbon dioxide. be able to.

  Regarding the method of blending the polyamide resin (A) and the smectite (B), a method of adding and stirring the smectite (B) during the melt polymerization of the polyamide resin (A), a single-screw or twin-screw extruder or the like is usually used. Although the method of melt-kneading using various extruders etc. is mentioned, Among these, the method using a twin-screw extruder is preferable from points, such as productivity and versatility.

  The melt kneading temperature when using the twin-screw extruder is adjusted to the melting point (Tm) to (Tm + 70) ° C. of the polyamide resin (A), the residence time is adjusted to 5 minutes or less, and the screw is at least one reverse screw element or It is preferable to carry out while having a kneading disk and retaining a part in this part.

  When the melt-kneading temperature is lower than 240 ° C., poor dispersion of the layered silicate is likely to occur, and when it exceeds 300 ° C. or when the residence time exceeds 5 minutes, the molecular weight is decreased due to the thermal decomposition of the polyamide or gel is likely to occur. Therefore, it is not preferable. Moreover, the dispersibility of layered silicate improves by providing a retention part in a screw. In general, the melt kneading time is particularly preferably adjusted to 1 to 5 minutes from the viewpoint of dispersibility, thermal decomposition, and gel generation suppression.

  In the present invention, nylon 6, nylon 66, nylon 6, 66, and other copolymer nylon resins can be used as the aliphatic polyamide resin (D). If necessary, blend other resins such as polyester, olefin, etc., plate-like inorganic fillers such as talc, kaolin and mica, impact modifiers such as various elastomers, crystal nucleating agents, fatty acid amides, Fatty acid metal salts, lubricants such as fatty acid amide compounds, copper compounds, organic or inorganic halogen compounds, hindered phenols, hindered amines, hydrazines, sulfur compounds, phosphorus compounds, antioxidants, heat stabilizers Additives such as anti-coloring agents, benzotriazole-based UV absorbers, mold release agents, plasticizers, coloring agents, flame retardants, and the like can be used.

  In the polyamide resin composition (E), the addition amount of the aliphatic polyamide resin (D) is preferably in the range of 90 to 60% by mass (the polyamide resin composition (C) is 10 to 40% by mass). When the addition amount of the aliphatic polyamide resin (D) is larger than this, the barrier property is deteriorated. If the added amount of the aliphatic polyamide resin (D) is less than this, the linear cut property is deteriorated.

  In order to obtain the polyamide resin composition (E) from the polyamide resin composition (C) and the aliphatic polyamide resin (D), a product obtained by mechanically mixing both resins can be used. Moreover, what was previously melt-kneaded can also be used.

  In the present invention, a film obtained by biaxially stretching a polyamide resin composition (E) comprising a polyamide resin composition (C) and an aliphatic polyamide resin (D) in advance is used as a polyolefin film using an adhesive. It can be used after being laminated. Alternatively, the polyamide resin composition (E), the adhesive resin, and the polyolefin resin can be melted, extruded in a multi-layered state to obtain an original film, and then stretched to obtain a stretched film.

  Stretching requires biaxial stretching, and uniaxial stretching deteriorates the linear cut property. The biaxially stretched film can be produced by any of the simultaneous biaxial stretching method and the sequential biaxial stretching method. Stretching can be produced by either a T-die method or a circular die method.

  In the stretched film of the present invention, the layer made of the polyamide resin composition (E) preferably has a thickness of 5 to 30 μm, more preferably 10 to 20 μm. When the thickness is thin, the barrier property as a film is lowered, and when the thickness is thick, the linear cut property is deteriorated. The stretched film of the present invention has a haze (cloudiness value) of 10% or less at a thickness of 15 microns and is excellent in transparency.

  The stretched film having the linear cut property of the present invention obtained by the above can be suitably used as a packaging material for individual packaging of sweets such as Japanese confectionery and Western confectionery, boiled retort food, delicacy, processed meat products, etc. Trouble at the time of unpacking can be prevented.

  Hereinafter, the present invention will be specifically described with reference to examples and the like. In Examples and the like, the polyamide resin and the stretched film were evaluated according to the following methods.

-Relative viscosity of polyamide resin 1 g of polyamide was precisely weighed and dissolved in 100 ml of 96% sulfuric acid at 20-30 ° C with stirring. After complete dissolution, 5 ml of the solution was quickly taken into a Cannon Fenceke viscometer, and left for 10 minutes in a thermostatic bath at 25 ° C., and then the drop time (t) was measured. Further, the dropping time (t0) of 96% sulfuric acid itself was measured in the same manner. The relative viscosity was calculated from t and t0 according to the following formula.
Relative viscosity = (t) / (t0)

-Oxygen transmission rate It carried out according to ASTM D3985. A model manufactured by Modern Control Co., Ltd. (Model: OXTRAN 10 / 50A) is used. The measurement conditions are a temperature of 23 ° C., a relative humidity of 100% on the inner surface of the container, and a relative humidity of 50% on the outer side of the container.

・ Straight line cut 50mm wide and 20cm long film with a 20mm length cut at the midpoint of one short side at right angles to the short side. Torn to the short side on the opposite side. Expressed by the length of the gap from the midpoint of the short side of the tearing end point The smaller the deviation, the better the linear cut performance.

・ Transparency (haze)
Using a color difference / turbidity measuring device COH-300A manufactured by Nippon Denshoku Industries Co., Ltd., the haze of the film was measured according to ASTM D1003.

<Example 1>
A jacketed 50 L reaction vessel equipped with a stirrer, a partial condenser, a cooler, a dripping tank, and a nitrogen gas introduction tube was charged with 10 kg of adipic acid, sufficiently purged with nitrogen, and further 160 ° C. under a small amount of nitrogen stream. And dissolved uniformly. To this, 9.2 kg of metaxylylenediamine was added dropwise over 170 minutes with stirring. During this time, the internal temperature was continuously increased to 247 ° C. Water distilled with the addition of metaxylylenediamine was removed out of the system through a condenser and a condenser. After completion of the dropwise addition of metaxylylenediamine, the internal temperature was raised to 260 ° C. and the reaction was continued for 1 hour. The obtained polymer was taken out as a strand from the nozzle at the bottom of the reaction can, cooled with water and then cut into pellets to obtain melt-polymerized polymetaxylylene adipamide. The metaxylylene adipamide pellets were placed in a 250 L solid phase polymerization apparatus and rotated at 18 rpm. Vacuuming was performed to 5 Torr or less, and the operation of bringing the pressure to 99 atmospheric pressure or higher and normal pressure was performed three times. Thereafter, the temperature was raised from room temperature to 140 ° C. Vacuuming was started after the pellet temperature reached 140 ° C., and the temperature was further raised. When 110 minutes had elapsed since the start of evacuation, the pellet temperature reached 200 ° C., and heating was stopped. Nitrogen was introduced to normal pressure to obtain polyamide MXD6 (polyamide (A)). 97 parts by mass of this polyamide (A) and smectite (montmorillonite: montmorillonite was used as an organic swelling agent and treated with dimethyldioctadecyl ammonium salt (content after treatment: 42 mass%) manufactured by Shiraishi Kogyo Co., Ltd. After dry blending 3 parts by mass with the name “NEW-D Orben”), the mixture was fed at a rate of 6 kg / hr to a twin screw extruder having a cylinder diameter of 37 mm and a retentive part by a reverse element using a weighing feeder. Melt kneading was performed under the conditions of a cylinder temperature of 270 ° C., a screw rotation speed of 500 rpm, and a residence time of 110 seconds. The molten strand was cooled and solidified with cooling air, and then pelletized to obtain polyamide (C).
30 parts by weight of polyamide (C) and 70 parts by weight of nylon 6 (hereinafter referred to as polyamide (D) as aliphatic polyamide resin (D). Ube Industries, trade name: Ube nylon 1024B) are mixed, and this is mixed with the cylinder diameter. Was extruded at 260 to 270 ° C. from a 20 mm extruder (Toyo Seiki Seisakusho, Labo Plast Mill), and a 300 μm thick raw film was prepared by the T-die-cooling roll method. The obtained film was biaxially stretched 3 times in the TD and MD directions at a stretching temperature of 110 degrees using a biaxial stretching device (tenter method) manufactured by Toyo Seisakusho Co., Ltd. to obtain a stretched film. It was. Table 1 shows the results of measuring the transparency (haze), linear cutability, and oxygen permeability of the film obtained.

<Example 2>
The stretched film obtained in Example 1 was used as a front substrate film, and an LLDPE film (manufactured by Idemitsu Petrochemical Co., Ltd., trade name: Unilux LS722C, thickness 50 μm) was used as a sealant film, and both were dry laminated. A laminate film was obtained. Table 2 shows the results of measuring the transparency (haze), linear cutability, and oxygen permeability of the film obtained.

<Example 3>
In advance, 30 parts by weight of the polyamide (C) obtained in Example 1 and 70 parts by weight of the polyamide (D) were mixed to prepare a mixed resin. Linear low-density polyethylene (forms c layer. Made by Mitsui Chemicals, Inc., trade name: ULT ZEXX 2022L, hereinafter abbreviated as LLDPE), cylinder diameter is 40 mm from an extruder with a cylinder diameter of 45 mm. Adhesive polyethylene (forms b layer, manufactured by Mitsui Chemicals, Inc., trade name: Admer NF300) and a mixed resin for a barrier layer (forms a layer) from an extruder having a cylinder diameter of 30 mm. Extruded at 200 to 210 ° C., 190 to 200 ° C., and 260 to 270 ° C., respectively, a multilayer molten state is formed through a feed block so that the layer structure is in the order of c layer / b layer / a layer, A multilayer film was produced by a water-cooled inflation method. The obtained multilayer film was simultaneously biaxially stretched at a stretching temperature of 100 ° C. by a tubular method, and further heat-set to obtain a stretched film. Table 2 shows the layer structure, thickness, and transparency (haze) of the multilayer film produced, the linear cut property, and the oxygen permeability measurement results.

<Comparative Example 1>
Using the same apparatus as in Example 1, a stretched film was prepared in the same manner as in Example 1 except that 30 parts by weight of polyamide (A) and 70 parts by weight of polyamide (D) were used instead of polyamide (C). . Table 1 shows the results of measuring the transparency (cloudiness value), linear cutability, and oxygen permeability of the film obtained. The oxygen transmission rate was not satisfactory with 170 ml / m ² · day · MPa.

<Comparative example 2>
Using the same apparatus as in Example 1, 30 parts by weight of polyamide (A) and smectite instead of polyamide (C) were added to nylon 6 (nanocomposite nylon 6. In Table 1, it was indicated as polyamide (D).) A stretched film was produced in the same manner as in Example 1 except that 70 parts by weight was used. Table 1 shows the results of measuring the transparency (haze), linear cutability, and oxygen permeability of the film obtained. The transparency was not satisfactory with a haze value of 12.5%.

  As is clear from the results in Tables 1 and 2, the stretched film of the present invention is excellent in linear cut property, transparency, and barrier property.

  The stretched film of the present invention can be suitably used as a packaging material for individual packaging of sweets, boiled / retort food, delicacy, processed meat products, and the like.

Claims (7)

A polyamide resin obtained by polycondensation of a diamine component containing 70 mol% or more of metaxylylenediamine and a dicarboxylic acid component containing 70 mol% or more of an α, ω-linear aliphatic dicarboxylic acid having 4 to 20 carbon atoms ( A polyamide resin composition (C) containing 10 to 40% by mass of fat and a smectite treated with an organic swelling agent (smectite (B)) in the range of 8 to 1% by mass in the range of 92 to 99% by mass of A) Stretched film having a linear cut property obtained by biaxially stretching a polyamide resin composition (E) composed of 90 to 60% by mass of an aromatic polyamide resin (D). The stretched film according to claim 1, wherein the polyamide resin composition (C) is one in which the smectite (B) is uniformly finely dispersed in the polyamide resin (A). 3. The stretched film according to claim 1, wherein the polyamide resin (A) has a relative viscosity (1 g / dl of 96% sulfuric acid solution, 25 ° C.) of 2.4 to 3.9. The stretched film according to any one of claims 1 to 3, wherein the smectite (B) is montmorillonite treated with an organic swelling agent. Content of the organic swelling agent in a smectite (B) is 20-50 mass%, The stretched film in any one of Claims 1-4 characterized by the above-mentioned. The stretched film according to any one of claims 1 to 5, wherein the aliphatic polyamide resin (D) is at least one selected from nylon 6, nylon 66 and nylon 6,66. The stretched film according to any one of claims 1 to 6, wherein the haze at a thickness of 15 microns is 10% or less.