JPH04368845A - Manufacture of laminate - Google Patents

Abstract

PURPOSE:To produce heat-sealable laminated film, which can be melt-adhered onto base material without utilizing anchor coating material at favorable bond strength by a method wherein the surface of specified ethylene-based copolymer melt film is ozonized. CONSTITUTION:Ethylene-based copolymer, which is obtained by copolymerizing 87.0-98.7mol% of ethylene, 0.3-3mol% of unsaturated polybasic acid and 1-10mol% of unsaturated monomer selected from the group consisting of lower alkylacrylic ester, lower alkylmethacrylic ester and vinyl ester, is melted and kneaded and, after that, extruded in the form of film at 150-330 deg.C. After the resultant film is ozonized, the film is laminated under pressure to base material under the condition that the ozonized surface is employed as the adhesive surface so as to obtain the desired laminate.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a method for manufacturing a laminate by extrusion lamination using a special ethylene resin film that exhibits excellent adhesive strength to a base material without using an anchor coating agent. Regarding.

[0002] This laminate film is used as a packaging material film for industrial parts, foods, etc., which requires chemical resistance, impact resistance, and easy heat sealability.

0003

[Prior art] As a packaging film for snacks, industrial parts, bacon, ham, fruits and vegetables, etc., the surface of the base material is subjected to corona discharge treatment, and after applying an anchor coating agent to this treated surface, an ethylene-based film is used as a heat-sealable resin layer. 31 resin
A laminate film manufactured by extruding an ethylene resin film through a die at 0 to 350°C onto a film, subjecting it to corona discharge treatment within the space (air gap) between the die and a cooling roll, and laminating it onto a base material (unexamined patent application) Showa 54-15847
No. 7) is used.

[0004] In addition, 1 g/m2 is applied to one side of a low-density polyethylene resin film, at least the surface of which is in a molten state, immediately after extrusion molding at an extrusion temperature of 290°C or lower.
A gas containing 3 or more ozone is sprayed at a rate of 50 ml/m2 or more, and then this low-density polyethylene resin film and a separate base sheet having an anchor coat layer made of an anchor coat agent on the surface are coated with a low-density polyethylene resin film. The ozone-treated surface of the density polyethylene resin film and the anchor coat layer surface of the base sheet are laminated in close contact with each other and pressed to produce a laminate (Japanese Patent Laid-Open No. 57-1
No. 02318).

[0005] Furthermore, the ethylene resin is extruded from a die of an extruder at a resin temperature of 150 to 290°C to form a molten thin film,
Next, after the molten thin film is treated with ozone, it is laminated by pressure bonding onto a substrate treated with an anchor coat, using the treated surface as an adhesive surface to produce a laminate (Japanese Patent Laid-Open No. 57-157).
No. 724).

[0006] As a base material, biaxially oriented polypropylene,
Polyethylene terephthalate, non-oriented polypropylene (
CPP), biaxially oriented polypropylene, cellophane, aluminum vapor-deposited products of these, and products bonded with paper and aluminum foil are used. In addition, as the ethylene resin for the heat-sealable resin layer, low-density polyethylene,
Ethylene/vinyl acetate copolymer (vinyl acetate content is 1.
8-10% by weight) [Packaging Special Issue (1973-3) pp. 212-215, 1973
Published by Packaging Co., Ltd. on April 15, 2017].

[0007]

In the conventional method, an anchor coating agent is used for adhesion between the base material and the heat-sealable resin layer.

[0008] As anchor coating agents, isocyanate-based, polyester/isocyanate-based, polyether/isocyanate-based, polyethyleneimine-based, and organic titanate-based agents are used, but these resins are usually coated with toluene, ethyl acetate, or methanol. , diluted with an organic solvent such as hexane. After these anchor coating agents are applied to a substrate, the organic solvent is scattered by drying, which is undesirable in terms of deterioration of working environment hygiene, risk of fire, and increased work frequency.

[0009] The present invention provides a method by which a heat-sealable resin film can be directly fused and laminated without anchor coating treatment on a base material.

0010

[Means for Solving the Problems] The present invention provides (a). 87.0-98.7 mol% ethylene; (b). 0.3 to 3 mol % of an unsaturated polybasic acid; (c). Unsaturated monomer selected from acrylic acid lower alkyl ester, methacrylic acid lower alkyl ester, and vinyl ester (however, the number of carbon atoms in the alkyl group of the alkyl ester is 1 to 8) 1 to
An ethylene copolymer obtained by copolymerizing 10 mol% of the ethylene copolymer is melt-kneaded and extruded into a film at a temperature of 150 to 330°C, and then the film is treated with ozone, and the ozone-treated surface is used as an adhesive surface. The present invention provides a method for producing a laminate, which is characterized by pressure lamination on a base material.

Ethylene copolymer The ethylene copolymer has (a). Ethylene 87.0-9
8.7 mol %, and (b). 0.3 to 3 mol % of an unsaturated polybasic acid; (c). By polymerizing 1 to 10 mol% of an unsaturated monomer selected from lower alkyl acrylate, lower alkyl methacrylate, and vinyl ester (however, the number of carbon atoms in the alkyl group of the alkyl ester is 1 to 8). This is the obtained copolymer.

[0012] Polymerization is usually carried out at a temperature of 180 to 250°C under a pressure of 1000 to 2000 atm.

Examples of the unsaturated polybasic acid as component (b) include maleic anhydride, itaconic anhydride, citraconic anhydride, himic anhydride, methylhimic anhydride, and derivatives thereof. Moreover, one or more types from the above group can be selected and used.

[0014] More preferred from the above group are maleic anhydride and itaconic anhydride.

The unsaturated monomer of component (c) includes acrylics such as methyl acrylate, ethyl acrylate, propyl acrylate, isobutyl acrylate, tert-butyl acrylate, 2-ethylhexyl acrylate, and octyl acrylate. Acid alkyl esters; methacrylic acid alkyl esters such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate; vinyl acetate, propion Vinyl esters such as vinyl acids are used.

The melting point of this ethylene copolymer is 85-1
10℃, density 0.925-0.955g/cm3,
Generally, MFR is 1 to 150 g/10 minutes.

[0017] The amount of unsaturated polybasic acid (b) is 0.3 mol%
If it is less than that, the adhesive strength between the base material and the heat-sealable resin layer is insufficient. If it exceeds 3 mol%, the extrusion properties of the film will deteriorate, making it impossible to extrude a film with uniform thickness.

If the amount of the unsaturated monomer (c) is less than 1 mol %, the adhesive strength between the base material and the heat-sealable resin layer will be low, and if it is more than 10 mol %, the melt extrusion properties will deteriorate and the film will have It is difficult to mold and the film has an odor.

In order to improve the extrusion characteristics of this ethylene copolymer (A), another ethylene resin (B) may be blended. Such ethylene resins include low density polyethylene, high density polyethylene, ethylene and 3 carbon atoms.
Copolymers with ~12 α-olefins (linear low-density polyethylene, etc.), ethylene/vinyl acetate copolymers, ethylene/(meth)acrylic acid ester copolymers, ethylene/vinyl acetate copolymers,
Examples include (meth)acrylic acid copolymers and ionomers made of them, and these may be used mutually or in a mixture of two or more.

In this case, ethylene copolymer (A) 30
-90% by weight, and the other ethylene resin (B) is blended in a proportion of 70-10% by weight.

An antioxidant, an antistatic agent, an antifogging agent, a nucleating agent, a dispersing agent, etc. may be added to the ethylene copolymer (A) or a resin composition containing this copolymer. The thickness of this layer is usually 8 to 40 μm.

[0022] As the base material in the present invention, resin films or sheets of polypropylene, polyamide, polyester, saponified products of ethylene-vinyl acetate copolymers, polyvinylidene chloride, polyvinyl alcohol, stretched products of these, aluminum, A product bonded with metal foil such as iron, cellophane, paper, cloth, nonwoven fabric, etc. is used, and its surface is subjected to corona treatment, frame treatment, etc. as necessary. The thickness of the base material layer is 5 to 220 μm, preferably 10 to 50 μm
It is. The base material may be printed.

The ethylene copolymer (A) of the present invention and the resin composition containing 30 to 90% by weight of the copolymer (A) are extruded through a die of an extruder to form a molten thin film. In this case, it is essential that the resin temperature is 150 to 330°C. If the resin temperature is less than 150°C, the spreadability of the resin will be poor, and not only will it be difficult to smoothly obtain a molten thin film with a uniform thickness, but the adhesive strength with the base material will be insufficient. Furthermore, if the temperature exceeds 330°C, oxidation of the surface of the molten resin will increase, and odor from the ethylene copolymer will also increase, resulting in poor heat sealability and odor when laminated.
This will result in other quality deterioration. Note that the preferred resin extrusion temperature is 200 to 320°C. In addition, when the copolymer (A) uses vinyl ester as the component (C), or when the ethylene resin (B) to be blended is an ethylene/vinyl acetate copolymer, 200
~260°C is the preferred resin extrusion temperature.

[0024] The heat-sealable resin layer may be laminated onto the base material on one or both sides of the base material layer.

[0025] In the present invention, it is essential that the side of the heat-sealable resin molten thin film and the surface to be bonded to the base material be subjected to ozone treatment within the air gap. Ozone treatment is performed by blowing ozone-containing gas (air, etc.) from a nozzle or slit-shaped outlet toward the surface of the molten thin film or toward the crimped portion between the molten thin film and the base material. . In addition, when carrying out extrusion lamination at a high speed of 100 m/min or more, it is preferable to spray toward the crimped part of the molten thin film and the base material. The ozone concentration in the sprayed gas is preferably 1 g/m2 or more, more preferably 3 g/m2 or more.
m2 or more. Further, the spraying amount is preferably 0.03 liter/min/cm or more, more preferably 0.1 liter/min/cm or more based on the width of the molten thin film. In this case, it should be avoided to increase the flow rate excessively, since this will cause the molten thin film to oscillate and become uneven in thickness.

[0026] The laminate can be used as it is as a film-like packaging material, or it can be heat-sealed and used as a bag. The wall thickness of the laminate is usually 10 to 250 microns.
Preferably it is 20 to 100 microns.

[0027]

[Operation] By treating the surface of a specific ethylene copolymer melt film with ozone, it is possible to produce a laminate by melt adhering it onto a substrate without using an anchor coating agent.

[0028]

EXAMPLES The present invention will be further explained below with reference to specific examples.

Example-1 A terpolymer (MFR 6 g/10 min) obtained by copolymerizing 93.9 mol% ethylene, 5.2 mol% methyl acrylate, and 0.9 mol% maleic anhydride was Melt and knead with an extruder with a diameter of 90 mm, and from a T-die, the resin temperature is 280 ° C.
A film with a width of 500 mm is extruded to form a molten thin film, and then an ozone concentration of 20 g /
One side of the molten film was ozonated by blowing m3 of air at a flow rate of 500 liters/hour.

Next, using a known extrusion laminator (the cooling roll has a semi-matte surface finish), the molten thin film is applied to the ozone-treated surface of the biaxially stretched nylon film having a thickness of 5 μm, which has been unwound from the unwinding section. The film was laminated using a pressure roll so that the surface of the biaxially stretched nylon film was the adhesive surface. The laminating speed at this time was 80m.
/min, and the thickness of the laminate layer was 30μ.

Regarding the obtained laminate (laminate),
Evaluation of the adhesive strength between the base material and the laminate layer, the heat sealing strength between the laminate layers (heat sealing conditions - temperature 140°C, pressure 2kg/cm2, time 1 second), and the drop resistance of the bag in which water is packaged with the laminate. did. During extrusion lamination, the peelability of the laminate from the cooling roll (
Stickiness) was visually observed. The results are shown in Table 1.

Example 2 Instead of the biaxially oriented nylon film in Example 1, a 15 μm thick biaxially oriented nylon film that had been subjected to corona discharge treatment (extrusion lamination on the corona discharge treated surface, corona discharge treatment amount was 30 μm) A laminate film was obtained under the same conditions except that the temperature was changed to (Watt·min/m2). The results are shown in Table 1.

Examples 3 and 4 In Example 2, the resin temperature of the ethylene terpolymer was
A laminate film was obtained under the same conditions except that the temperature was 10°C or 250°C. The results are shown in Table 1.

Example-5 Example 2 was used instead of the ethylene terpolymer in Example-2.
50% by weight of the ethylene terpolymer used in
A laminate film was obtained in the same manner except that a mixed resin containing 50% by weight (g/cm3) was used. The results are shown in Table 1.

Example 6 Instead of the terpolymer used in Example 2, 50% by weight of the terpolymer of Example 2 and an ethylene methyl acrylate copolymer (94 mol% of ethylene and methyl acrylate) were used. 6
A laminate film was obtained in the same manner except that the mixed resin was changed to a mixed resin with 50% by mole of copolymer (MFR 15g/10min). The results are shown in Table 1.

Example 7 The extruder and T die of Example 2 were changed to a coextrusion device with a diameter of 90 mm, an extruder with a diameter of 65 mm, and a multi-manifold type T die. Melt-knead the terpolymer used in Example-1,
Low density polyethylene (MFR) is produced from an extruder with a diameter of 65 mm.
15 g/10 minutes, density 0.919 g/cm3) were melt-kneaded, and two layers were coextruded from one multi-manifold type T die so that the terpolymer was placed on the base material side, and a molten thin film was formed. (The resin temperature was measured with a surface infrared thermometer, and the surface temperature directly under the T die was 285 mm on the terpolymer side.
℃, and the low density polyethylene side was 280℃).

The thickness of the coextruded laminate layer was 15 μm for the terpolymer and 15 μm for the low density polyethylene. The rest was the same as in Example 2. Table 1 shows the results of the obtained laminate film.

Comparative Example-1 A laminate film was obtained in the same manner as in Example-1 except that ozone treatment was not performed. The results are shown in Table 1.

Comparative Example 2 A laminate film was obtained in the same manner as in Example 2 except for the ozone treatment. The results are shown in Table 1.

Comparative Example 3 In Example 2, an ethylene/methyl acrylate binary copolymer (a copolymer of 94 mol% ethylene and 6 mol% methyl acrylate, MFR 15 g/1) was used instead of the terpolymer.
A laminate film was obtained in the same manner except that the temperature was changed to 0 minutes). The results are shown in Table 1.

Comparative Example-4 Low-density polyethylene (MFR 15g/10 min, density 0.919g) was used instead of the terpolymer used in Example-2.
A laminate film was obtained in the same manner except that the film was used in a laminate film (/cm3). The results are shown in Table 1.

Comparative Example-5 Instead of the terpolymer used in Example-1, Comparative Example-4 was used.
The laminate surface of the biaxially stretched nylon film was treated with an anchor coating agent (isocyanate-based anchor coating agent) using low-density polyethylene. Furthermore, a laminate film was obtained in the same manner as in Example 1 except that the resin temperature was changed to 320°C and the ozone treatment was omitted. The results are shown in Table 1.

[0043] In the anchor coating agent treatment, Nippon Soda Co., Ltd.'s Titabond T-120 was dissolved in ethyl acetate at a concentration of 4 wt%, applied to the base material by roll squeeze coating, and then the solvent was removed by evaporation with hot air at 100°C. .

Comparative Example-6 The terpolymer used in Example-1 was replaced with the low-density polyethylene used in Comparative Example 4, and the laminate surface of the biaxially stretched film was subjected to the anchor coating treatment of Comparative Example 5. A laminate film was obtained in the same manner as in Example-1 except that (isocyanate-based AC agent) was applied.

Measurement method (1). How to evaluate drop resistance strength: Put the laminate surfaces (heat-sealable resin layers) of the laminate film together and heat seal them to form a bag, then put 200cc of water in the bag, and then heat seal the entrance to prevent water from entering. A sealed bag was prepared (bag size: length 150 mm, width 100 mm, heat sealing conditions: temperature 140°C, pressure 2 kg/cm 2 , time 1 second).

On the other hand, the size is almost the same as the size of the bag,
Prepare an iron plate weighing 200 g, place the bag containing water on a smooth floor, drop this iron plate onto the bag containing water on a flat surface (increase the height every 10 cm and drop it), It is expressed as the maximum height at which the iron plate can fall until the bag on the floor does not break.

(2). During stick lamination of the cooling roll, peeling of the laminate layer from the cooling roll was visually observed.

Evaluation: ◯ - Almost no stick to the cooling roll. Good workability.

[0049] △ - There was a stick to the cooling roll, and during lamination processing, when starting at low speed, it adhered to the cooling roll, resulting in poor workability.

[0050] The abbreviations in Table 1 are as follows.

Resin-A; Ternary copolymer resin-B; Ternary copolymer (50) + low density polyethylene (50) Resin-C; Ternary copolymer (50) + EMA (50) Resin-D ;Low density polyethylene resin-E;EMA AC;Anchor coating agent

[0052]

[Table 1]

[0053]

[Effect] By treating the surface of a specific ethylene copolymer melt film with ozone, it is possible to produce a heat-sealable laminate film with good adhesive strength by melt-bonding it onto a base material without using an anchor coating agent. can.

Claims (2)

[Claims] [Claim 1] (a). Ethylene 87.0-98.7
mol % and (b). 0.3 to 3 mol % of an unsaturated polybasic acid; (c). Copolymerizing 1 to 10 mol% of an unsaturated monomer selected from acrylic acid lower alkyl ester, methacrylic acid lower alkyl ester, and vinyl ester (however, the number of carbon atoms in the alkyl group of the alkyl ester is 1 to 8). The obtained ethylene copolymer was melt-kneaded to give a
A method for producing a laminate, which comprises extruding the film into a film at a temperature of 30° C., then treating the film with ozone, and then laminating the film to a base material using the ozone-treated surface as an adhesive surface. [Claim 2] A) Component: (a). Ethylene 87.0
~98.7 mol %, and (b). Unsaturated polybasic acid 0.3~
3 mol %, and (c). Copolymerizing 1 to 10 mol% of an unsaturated monomer selected from acrylic acid lower alkyl ester, methacrylic acid lower alkyl ester, and vinyl ester (however, the number of carbon atoms in the alkyl group of the alkyl ester is 1 to 8). 30 to 90% by weight of the copolymer obtained by B)
A resin composition containing 70 to 10% by weight of ethylene resin (excluding component A) is melt-kneaded and extruded into a film at a temperature of 150 to 330°C, and then the film is treated with ozone. A method for producing a laminate, characterized by pressure-bonding lamination to a base material using the surface as an adhesive surface.