JP2002240213A - Olefin polymer laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an olefin polymer laminated film suitable for overlapping package having excellent interlayer adhesive properties and antistatic properties, low heat sealability, blocking resistance, slipperiness, solvent resistance and transparency. SOLUTION: The olefin polymer laminated film comprises a modified olefin polymer layer (B) and a metallic ion ionomer layer (C) of an ethylene/ unsaturated carboxylate copolymer sequentially laminated on at least one or both side surfaces of an olefin polymer base (A).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an olefin polymer laminated film having excellent low-temperature heat sealing properties, slip properties, blocking resistance, antistatic properties, solvent resistance, transparency and the like when used as a packaging material. More specifically, the present invention relates to an olefin polymer laminated film excellent for use in overlap packaging.

[0002]

2. Description of the Related Art A biaxially oriented polypropylene film (OPP film) obtained by molding and processing polypropylene, which is one of olefin polymers, has a low-temperature heat-sealable low-density polyethylene or ethylene-vinyl acetate film on one or both surfaces. A so-called heat-sealable OPP film obtained by coating or extruding and laminating a polymer having a low melting point, such as a polymer, polyvinylidene chloride, ethylene / (meth) acrylic acid copolymer, has transparency, mechanical properties, moisture resistance, and heat resistance. And is widely used as a film for overlapping packaging of tobacco, chocolate, caramel, bread, snacks, cassette tape, video tape, floppy (registered trademark) disk and the like.

As one of such low melting point polymers, there has been proposed a film obtained by coating a so-called ionomer obtained by neutralizing an ethylene / (meth) acrylic acid copolymer with metal ions on an OPP film (Japanese Patent Application Laid-Open No. Hei 8-509572). Gazette).

However, a laminated film obtained by directly or corona-treating the ionomer of the OPP film and then anchoring it with poly (ethyleneimine) or the like does not have sufficient interlayer adhesion or antistatic properties, and is not suitable for use as a packaging film. It has been found that there is a risk of delamination or dust on the package.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an overwrap package having excellent interlayer adhesion and antistatic properties, and having low-temperature heat sealability, blocking resistance, slipping properties, solvent resistance and transparency. It is an object of the present invention to provide an olefin polymer laminated film which is particularly suitable for the above.

[0006]

[Means for Solving the Problems]

SUMMARY OF THE INVENTION The present invention provides a modified olefin polymer layer (B) and a metal ion ionomer layer of an ethylene / unsaturated carboxylic acid copolymer (C) on at least one surface, preferably both surfaces, of an olefin polymer substrate (A). ) Are sequentially laminated, and have excellent interlayer adhesion and antistatic properties,
Low temperature heat sealability, blocking resistance, slip property,
It is an olefin polymer laminated film having solvent resistance and transparency and particularly suitable for use in overlap packaging.

Another feature of the present invention is the olefin polymer laminated film in which the olefin polymer substrate (A) is stretched, preferably biaxially stretched, in the above-mentioned laminated film.

Another feature of the present invention is the above-mentioned laminated film, wherein the modified olefin polymer layer (B) is graft-modified with an unsaturated carboxylic acid or a derivative thereof.

A further feature of the present invention is an olefin polymer laminated film in which the metal ionomer layer (C) in the above laminated film has a degree of neutralization by potassium ions of 70% by weight or more.

According to the present invention, a modified olefin polymer layer (B) and a potassium ionomer layer of an ethylene / unsaturated carboxylic acid copolymer (D) are sequentially formed on one surface of an olefin polymer substrate (A). A metal ion ionomer layer (E) excluding a potassium ion of an ethylene / unsaturated carboxylic acid copolymer, which is laminated on another surface of the olefin polymer base material (A); It is a united laminated film.

[0011]

DETAILED DESCRIPTION OF THE INVENTION Olefin polymer substrate (A) The olefin polymer constituting the olefin polymer substrate (A) in the present invention is ethylene, propylene, 1-butene, 1-hexene, 1-octene, A homo- or copolymer of an α-olefin having 2 to 10 carbon atoms such as 4-methyl-1-pentene, which is usually a high-pressure low-density polyethylene, a linear low-density polyethylene, a high-density polyethylene, a polypropylene, a poly-1-butene, A generally crystalline thermoplastic resin known as poly-4-methyl-1-pentene and the like. Among them, homopolymers of propylene or copolymers of propylene with other α-olefins such as ethylene and 1-butene in a small amount of 5 mol% or less, which are called polypropylene, have high transparency and rigidity. It is preferable because a substrate having excellent solvent resistance and the like can be obtained.

The molecular weight of the olefin polymer is not particularly limited as long as the olefin polymer has a molecular weight sufficient to form a film, but it is usually ASTM D1238 (230
A melt flow rate (MFR) of 0.01 to 100 g / min, more preferably 0.1 to 10 g / min, measured according to (° C, load 2,160 g) is advantageously used. Also, a stretched film, particularly a biaxially stretched film, is the most preferable since it further becomes a substrate excellent in transparency, rigidity, solvent resistance and the like.

Modified Olefin Polymer Layer (B) In the present invention, the modified olefin polymer constituting the modified olefin polymer layer (B) is, in addition to the above-mentioned crystalline olefin polymer, an ethylene / α-olefin random copolymer, A low-crystalline or amorphous olefin polymer such as a propylene / α-olefin random copolymer is modified by adding a polar group. Among them, those graft-modified with an unsaturated carboxylic acid or a derivative thereof can improve the adhesion between the olefin polymer base material (A) and the metal ionomer layer (C) of the ethylene / unsaturated carboxylic acid copolymer. It is preferable because it is excellent.

Examples of the unsaturated carboxylic acid or a derivative thereof include acrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, and nadic acid (endosis-bicyclo [2.2. 1] Unsaturated carboxylic acids such as hept-5-ene-2,3-dicarboxylic acid); and derivatives thereof, for example, acid halides, amides, imides, anhydrides, esters and the like. Specific examples of such derivatives include maleenyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, glycidyl maleate and the like. Of these, unsaturated dicarboxylic acids or acid anhydrides thereof are preferred, and maleic acid, nadic acid or acid anhydrides thereof are particularly preferably used.

The modified olefin polymer graft-modified with an unsaturated carboxylic acid or a derivative thereof is preferably 0.05 to 15% by weight, more preferably 0.1 to 10% by weight, based on the olefin polymer before modification. Graft-modified with an unsaturated carboxylic acid or a derivative thereof.
The modified olefin polymer preferably has a melt flow rate (MFR, 230 ° C.) of 0.1 to 50 g / 10.
Min, more preferably 0.3 to 30 g / 10 min of MFR. The melt flow rate was measured according to ASTM D1238 (190 ° C. for ethylene polymer, 230 ° C. for propylene polymer, load 2,160 g).

Ethylene / unsaturated carboxylic acid copolymer gold
Group ion ionomer layer (C) The metal ion ionomer of the ethylene / unsaturated carboxylic acid copolymer constituting the metal ion ionomer layer (C) in the present invention is an ethylene / unsaturated carboxylic acid copolymer represented by Ia, An amount of at least one metal ion of group IIa or IIb, preferably lithium, sodium,
Neutralized with potassium, rubidium, cesium, calcium or zinc ions, preferably at least 60%, particularly preferably at least 70%, and the total amount of metal ions is 0.4 to 4 mol / kg, especially 0 to 4 mol / kg of metal ion ionomer. It is preferably in the range of 0.6 to 2 mol. Among them,
Ionomers neutralized with potassium, rubidium, cesium ions, particularly potassium ions, are preferred because a laminated film having excellent antistatic properties can be obtained.

Such a metal ion ionomer can also be produced, for example, by saponifying an ethylene / unsaturated carboxylic acid ester copolymer.
Further, the MFR (190)
° C, 2160 g load) is usually 0.01 to 1000 g /
It is in the range of 10 minutes, preferably 0.1 to 100 g / 10 minutes.

The ethylene / unsaturated carboxylic acid copolymer serving as the base polymer of the metal ion ionomer is obtained by copolymerizing ethylene and an unsaturated carboxylic acid, and optionally other monomer components. Ethylene is 60 ~
90% by weight, preferably 70 to 88% by weight, unsaturated carboxylic acid 10 to 40% by weight, preferably 12 to 30% by weight, and other monomer components 0 to 30% by weight, preferably 0 to 0% by weight.
The copolymer is randomly copolymerized at a ratio of 20% by weight. In addition, a similar random copolymer having an ethylene content higher than that described above and therefore having an unsaturated carboxylic acid content lower than that described above may be used together with such a random copolymer.

Examples of such unsaturated carboxylic acids include acrylic acid, methacrylic acid, fumaric acid, monomethyl maleate, monoethyl maleate, and maleic anhydride, and acrylic acid or methacrylic acid is particularly desirable. Other optional monomer components include unsaturated carboxylic acid esters such as methyl acrylate, ethyl acrylate, isopropyl acrylate, isobutyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate. And methyl methacrylate and isobutyl methacrylate, and vinyl esters such as vinyl acetate and vinyl propionate.

Such a copolymer can be obtained by radical copolymerization of each polymerization component under high temperature and high pressure in the same manner as in the high-pressure polyethylene.

Olefin Polymer Laminated Film The olefin polymer laminated film of the present invention comprises a modified olefin polymer layer (B) and an ethylene / unsaturated carboxylic acid copolymer on at least one side, preferably both sides, of the olefin polymer substrate (A). A polymer metal ionomer layer (C) is sequentially laminated. In the olefin polymer laminated film of the present invention, a modified olefin polymer layer (B) is interposed between an olefin polymer substrate (A) and a metal ion ionomer layer of an ethylene / unsaturated carboxylic acid copolymer (C). Thereby, the interlayer adhesion is improved, and the possibility of delamination occurring even when used as a packaging film is eliminated. When a metal ion ionomer neutralized with potassium ions is used as the metal ion ionomer, a laminated film having excellent antistatic properties can be obtained. When the metal ion ionomer neutralized with potassium ions is used, a laminated film having excellent interlayer adhesion with the olefin polymer substrate (A) cannot be obtained unless the modified olefin polymer layer (B) is used. There is a fear.

The olefin polymer laminated film of the present invention comprises a modified olefin polymer layer (B) and a potassium ion ionomer layer of an ethylene / unsaturated carboxylic acid copolymer on one surface of an olefin polymer substrate (A). (D) are sequentially laminated, and a metal ion ionomer layer (E) excluding potassium ions of the ethylene / unsaturated carboxylic acid copolymer is laminated on another surface of the olefin polymer base material (A).

The olefin polymer substrate (A)
The surface on which the potassium ionomer layer (D) of the unsaturated carboxylic acid copolymer is laminated may be delaminated without the intervention of the modified olefin polymer layer (B), and the ethylene of the olefin polymer substrate (A) The surface of the unsaturated carboxylic acid copolymer on which the metal ion ionomer layer (E) excluding potassium ions is laminated does not necessarily need to be interposed through the modified olefin polymer layer (B).

The thickness of each layer is not particularly limited, and is appropriately selected in consideration of packaging suitability, mechanical strength, flexibility and the like. Usually, the thickness of the olefin polymer substrate (A) is 3 μm to 90 μm.
μm, preferably 5 μm to 45 μm, and the modified olefin polymer layer (B) was 0.1 μm to 10 μm, preferably 0.1 μm to 10 μm.
3 μm to 5 μm, a potassium ionomer layer (D) of an ethylene / unsaturated carboxylic acid copolymer,
Each of the metal ionomer layers (E) excluding potassium ions of the unsaturated carboxylic acid copolymer has a thickness of 0.1 μm to 10 μm.
m, preferably about 0.2 μm to 5 μm, and 3 μm to 100 μm, preferably 5 μm to
It is in the range of 50 μm.

Each laminated surface of the olefin polymer laminated film of the present invention may be subjected to surface treatment or anchor coating. Examples of the surface treatment include corona discharge treatment, plasma treatment, glow discharge treatment, reverse sputtering treatment, flame treatment, chromic acid treatment, solvent treatment, and surface roughening treatment. The anchor coating agent can be composed of various known resins, for example, a thermoplastic resin, a thermosetting resin, a light-curing resin, and a coupling agent. By these surface modifications, the adhesion between the olefin polymer base material (A), the modified olefin polymer layer (B) and the metal ionomer layer of the ethylene / unsaturated carboxylic acid copolymer (C) can be improved. be able to.

On the other hand, in order to improve the antistatic performance of the olefin polymer film, when an antistatic agent is blended and the surface of the film containing the antistatic agent is subjected to corona discharge treatment, the antistatic agent spreads on the film surface. Outer surface specific resistance decreases and antistatic performance further improves,
Deterioration of the film surface due to the corona discharge treatment or oozing out of the antistatic agent has the disadvantage that the heat sealing start temperature increases or the heat sealing strength decreases.

However, a film in which a potassium ion ionomer layer (D) of an ethylene / unsaturated carboxylic acid copolymer is laminated on the surface of an olefin polymer film containing an antistatic agent, has a heat sealing starting temperature of less than a corona discharge treatment. The printability and the antistatic property can be improved with little increase and a decrease in heat seal strength does not occur to the left.

The thermoplastic resin constituting the olefin polymer substrate (A), the modified olefin polymer layer (B) and the metal ion ionomer layer of the ethylene / unsaturated carboxylic acid copolymer (C) in the present invention includes: Heat stabilizers, weather stabilizers, UV absorbers, lubricants, slip agents, nucleating agents, anti-blocking agents, antistatic agents, anti-fog agents, pigments, dyes, inorganic or organic Various additives such as a filler may be added in a range that does not impair the purpose of the present invention.

Method for Producing Olefin Polymer Laminated Film The olefin polymer laminated film of the present invention can be produced by various known methods. For example, an unstretched film previously obtained by a melt molding method such as T-die molding or inflation molding, a casting method using a solution, or an olefin polymer substrate (A) composed of a uniaxially or biaxially stretched film. Extruding and laminating the modified olefin polymer layer (B), performing corona discharge treatment, applying an aqueous dispersion of a metal ion ionomer of an ethylene / unsaturated carboxylic acid copolymer to form a layer (C), The multilayer film obtained by co-extrusion of the polymer and the modified olefin polymer is stretched in the machine direction, and the surface of the modified olefin polymer layer (B) is corona-treated. For example, a method of applying an aqueous dispersion of an ion ionomer and stretching in the horizontal direction while drying or after drying is used. As a method of applying the aqueous dispersion of the metal ion ionomer, conventional methods such as a gravure coating method, a reverse coating method, a roll coating method, a bar coating method, a spray coating method, and an air knife coating method can be adopted, and these are appropriately combined. It is also possible to carry out.

The preferred concentration of the solid content in the aqueous dispersion is usually from 1 to 30% by weight, more preferably from 5 to 25% by weight.
% By weight. If the solid content concentration of the dispersion is 1% or less, thick coating is required to obtain a constant coating film thickness, and there is a possibility that productivity may be deteriorated, and wettability may also be reduced. If it is 30% or more, the viscosity is high, and application unevenness may occur. As the dispersing medium, water is preferably used from the viewpoint of cost and working environment, but solvents other than water, for example, methanol, ethanol, alcohols such as isopropanol, acetone, ketones such as methyl ethyl ketone, and other diethyl ether, tetrahydrofuran and the like If necessary, one kind or a combination of two or more kinds can be added.

[0031]

The olefin polymer laminated film of the present invention is excellent in low-temperature heat sealing properties, slip properties, blocking resistance, antistatic properties, solvent resistance, transparency and the like. It can be used for packaging materials such as food packaging materials, pharmaceutical products, electronic device parts, etc.

[0032]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Evaluation of the characteristics in the examples and comparative examples was performed by the following method. (1) Heat-sealing properties Samples cut into strips of 3 cm wide by 20 cm long are overlaid on the front and back, and a thermal gradient sealer (TOYO SEIKI SEISAKUSHO, TYPE
HG-100), and heat-sealed under the conditions of a sealing pressure of 1 kg / cm ² and a sealing time of 0.5 ^second , and then using a tensile testing machine (Tensilon universal testing machine: RTM-100, manufactured by Orientec) to obtain 90 The peel strength was measured. (2) Slip Property Using a slip tester (Yasuda Seiki Seisakusho No. 162-special type), the static friction coefficient between the front and back of the film sample was measured. (3) Surface specific resistance value The sample was cut into 10 cm x 10 cm, and left in a room at 20 ° C and a relative humidity of 60% for about 1 hour. Then, under the same conditions, a surface resistivity meter (Advantest, R83
Using 40), the surface resistivity of the sample film was measured.

Example 1 An intermediate layer made of polypropylene having a melting point of 162 ° C. and an MFR of 2 g / 10 minutes was used.
After stretching a co-extruded multilayer film laminated with modified polypropylene grafted with maleic anhydride for 0 minutes five times in the machine direction, a methacrylic acid content of 2
0% by weight, 100 parts by weight of a potassium salt of an ethylene / methacrylic acid copolymer having a neutralization degree of potassium hydroxide of 90%, 2 parts by weight of a slip agent (ethylene bisoleic acid amide), and a surfactant (alkanesulfonic acid) Sodium) 2
Weight and anti-blocking agent (average particle size 1.2 μm
Aqueous dispersion (concentration: 20%) containing 0.1 parts by weight of polymethyl methacrylate particles) was coated on the modified polypropylene layer by gravure roll in an amount of 20 cc and dried. Then, the film was stretched 10 times in a transverse direction in a tenter in which hot air of 160 ° C. was circulated, and then fixed with hot air at 150 ° C. for 5 seconds to obtain a biaxially stretched polypropylene laminated film. The thickness of each layer of the obtained laminated film was 23 μm for the intermediate layer of the polypropylene film, 1 μm for the modified polypropylene layer, and the coating amount of the potassium salt of the ethylene / methacrylic acid copolymer was 0.4 g / m ² . Table 1 shows the evaluation results.

Example 2 The modified polypropylene used in Example 1 was replaced with a melting point of 1
A biaxially stretched laminated polypropylene laminated film was obtained in the same manner as in Example 1 except that a modified random polypropylene graft-modified with maleic anhydride having an MFR of 5.7 at 35 ° C. was used. Table 1 shows the evaluation results.

Example 3 Melting point: 163 ° C., MFR: 2 g / 10
And a modified polypropylene graft-modified with maleic anhydride having a melting point of 165 ° C. and MFR of 3 g / 10 minutes is laminated on one side (front side) of the intermediate layer, and a melting point of 162 ° C. and MFR of 2 g / 10 on the other side (back side). Of the co-extruded multilayer film laminated with polypropylene for 5 times in the machine direction and subjected to a corona discharge treatment, and then the surface of the sheet is coated with ethylene having a methacrylic acid content of 20% by weight and a neutralization degree of potassium hydroxide of 90 mol%. A slip agent (ethylene bisoleic acid amide) 2 parts by weight, a surfactant (sodium alkane sulfonate) 2 parts by weight, and an anti-blocking agent (average particle diameter 1 Aqueous dispersion (concentration: 20%) containing 0.1 parts by weight of polymethyl methacrylate particles of 0.2 μm) 20 cc coated with a roll, and 100 parts by weight of a sodium salt of an ethylene / methacrylic acid copolymer having a methacrylic acid content of 15% by weight and a degree of neutralization of sodium hydroxide of 54 mol% on the back side, and a slip agent (ethylenebisolein) Aqueous dispersion (concentration: 20%) containing 5 parts by weight of an acid amide, 4 parts by weight of a surfactant (sodium alkane sulfonate) and 0.1 part by weight of an anti-blocking agent (polymethyl methacrylate particles having an average particle diameter of 1.2 μm) ) Was coated with a gravure roll at 20 cc and dried. Next, the film was stretched 10 times in the transverse direction in a tenter in which hot air of 160 ° C. was circulated, and then fixed with hot air at 150 ° C. for 5 seconds, and the surface was subjected to corona discharge treatment to obtain a biaxially oriented polypropylene laminated film. The thickness of each layer of the obtained laminated film is 23 μm for the intermediate layer of the polypropylene film.
m, the modified polypropylene layer was 1 μm, the polypropylene layer was 1 μm, and the coating amounts of the potassium salt of the ethylene / methacrylic acid copolymer and the sodium salt of the ethylene / methacrylic acid copolymer were 0.4 g / m ² , respectively. Table 1 shows the evaluation results.

Comparative Example 1 The modified polypropylene used in Example 1 was replaced with a melting point of 1
A biaxially stretched laminated polypropylene laminated film was obtained in the same manner as in Example 1 except that polypropylene at 62 ° C. and MFR of 2 g / 10 min was used. Table 1 shows the evaluation results.

Comparative Example 2 An aqueous dispersion of a sodium salt of an ethylene / methacrylic acid copolymer used in Example 3 was used instead of the aqueous dispersion of a potassium salt of the ethylene / methacrylic acid copolymer used in Comparative Example 1. Was performed in the same manner as in Comparative Example 1 except that Table 1 shows the evaluation results.

Table 1

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Claims (8)

[Claims] 1. A modified olefin polymer layer (B) and an ethylene olefin polymer layer (B) on at least one surface of an olefin polymer substrate (A).
An olefin polymer laminated film, wherein an unsaturated carboxylic acid copolymer and a metal ionomer layer (C) are sequentially laminated. 2. A modified olefin polymer layer (B) and a metal ionomer layer of an ethylene / unsaturated carboxylic acid copolymer (C) are sequentially laminated on both surfaces of an olefin polymer substrate (A). An olefin polymer laminated film characterized by the above-mentioned. 3. The olefin polymer laminated film according to claim 1, wherein the olefin polymer substrate (A) is stretched. 4. The olefin polymer laminated film according to claim 1, wherein the modified olefin polymer layer (B) is graft-modified with an unsaturated carboxylic acid or a derivative thereof. 5. The metal ionomer layer (C) has a degree of neutralization by potassium ions of 70% by weight or more.
Or the olefin polymer laminated film according to 2. 6. A modified olefin polymer layer (B) and a potassium ionomer layer of an ethylene / unsaturated carboxylic acid copolymer (D) on one surface of an olefin polymer substrate (A).
Are sequentially laminated, and a metal ion ionomer layer (E) excluding potassium ions of the ethylene / unsaturated carboxylic acid copolymer is laminated on another surface of the olefin polymer base material (A). Olefin polymer laminated film. 7. The olefin polymer laminate film according to claim 4, wherein the olefin polymer base material (A) contains an antistatic agent and the surface of the potassium ionomer layer is subjected to corona discharge treatment. 8. The olefin polymer laminated film according to claim 1, wherein the olefin polymer laminated film is an overlap packaging film.