JPH0379342A - Laminate for easy release packing material - Google Patents

Abstract

PURPOSE:To form a laminate for an easy release packing material by successively laminating a metal layer, an adhesive layer containing a vinyl chloride type graft polymer and an easy release resin layer containing a specific resin and an adhesiveness imparting agent. CONSTITUTION:A metal layer, an adhesive layer of an AC agent containing a graft polymer obtained by reacting unsaturated carboxylic acid or an anhydride thereof with a vinyl chloride/vinyl acetate copolymer and an easy release resin layer containing at least one resin among an ethylene/vinyl acetate copolymer resin, an ethylene/acrylic ester copolymer resin and a polyolefinic resin and an adhesiveness imparting agent are successively laminated. That is, an aluminum foil and an easy release resin film are strongly bonded and the AC agent having heat resistance is used. By this method, when a lid body using this laminate as a packing material is sealed to a container main body made of plastic, a part thereof is released and hot water is poured in said main body to be allowed to stand and, thereafter, even when the remainder thereof is released, the release thereof is well performed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an easily peelable laminate for packaging materials, and more specifically to lids for cup noodle type instant ramen packaging, packaging for pudding, jelly, etc. The present invention relates to packaging materials used for lids.

[Conventional technology]

In order to make foods such as instant ramen noodles, pudding, and jelly easy to eat, the packaging body closes the opening of the container body with a lid, and the surrounding area is heat-sealed to the periphery of the opening of the container body. The structure is such that when you want to eat it, you can easily peel off the lid and pour boiling water over it, or insert a spoon to take out the contents.

Conventionally, the above-mentioned lids, especially the packaging materials for the lids of cup ramen, have been designed with the above-mentioned characteristics such as peelability from the container body, water resistance considering the contents, and heat resistance when pouring boiling water. Considering paper - polyethylene - aluminum foil - anchor coating agent (hereinafter referred to as AC agent) - polyethylene -
It is made of easily peelable resin. To produce the material for the lid with this configuration, three extrusion laminations are required: two for polyethylene and one for easily peelable resin.Normally, single (one extruder) or tandem (extrusion lamination) Since the process is carried out using two machines, two or three steps are required.

[Problem to be solved by the invention]

In the structure of the above packaging material, the aluminum foil is coated with an AC agent, polyethylene is laminated, and then the easily peelable resin is laminated.The aluminum foil and easily peelable resin film can be directly bonded using the AC agent. If possible, the above 2
The number of steps or three steps is reduced by one step to one or two steps, making it possible to improve production efficiency, save labor, and reduce costs.

From this point of view, for example, as described in JP-A No. 59-109357, a composition of paper-polyethylene-aluminum foil-AC agent-easily peelable resin is used, and ethylene-butene-1 copolymerization is used as the AC agent. Packaging materials using graft copolymers obtained by reacting unsaturated carboxylic acids or their anhydrides are also known.

However, for example, after filling a container body made of styrofoam with the contents and attaching a lid made of the above-mentioned material to the container body by heat-sealing, a part of it is peeled off, hot water is poured in, and the lid is peeled off. Close the part and temporarily secure it, 5
If you peel off the unpeeled part of the lid after a few minutes, the easily peelable resin layer will not peel off from the opening edge of the container body, and a film will remain on this opening, thus fulfilling the original purpose of the easy peeling lid. I can't.

The purpose of the present invention is to peel off a part of the lid attached to the container body made of Styrofoam by heat-sealing, pour boiling water into it, and then peel off the remaining part of the lid after a certain period of time has passed, the lid still remains attached to the container body. An object of the present invention is to provide an easily peelable laminate for packaging material that can be completely peeled off.

[Means to solve the problem]

As a result of intensive studies, the present inventors have found that A
The inventors have found that the above problems can be solved by using Agent C, and have come up with the present invention.

That is, the present invention provides a metal layer, an adhesive layer containing a graft polymer obtained by reacting a vinyl chloride-vinyl acetate copolymer with an unsaturated carboxylic acid or its anhydride, and an ethylene-vinyl acetate copolymer. An easily peelable packaging material comprising a laminate in which easily peelable resin layers containing at least one of a system resin, an ethylene-acrylic acid ester copolymer resin, and a polyolefin resin and a tackifier are sequentially laminated. The present invention provides a laminate for use in various applications. In this case, the tackifier must be at least one selected from the group of rosin, rosin-modified resin, terpene resin, terpene-modified resin, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, and alicyclic hydrocarbon resin. is preferred.

Next, the present invention will be explained in detail.

Examples of the metal used for the metal layer in the present invention include aluminum, iron, tin, nickel, lead, zinc, etc., and these are used as the metal foil. Note that composites of these metal foils with other base materials such as paper-polyethylene laminates, paper, polyester films, etc. may also be used.

Furthermore, the adhesive layer used in the present invention is a layer coated with an AC agent, which contains a resin in which an unsaturated carboxylic acid or its anhydride is grafted onto a vinyl chloride and vinyl acetate copolymer. Examples of the unsaturated carboxylic acid or anhydride thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, and itaconic anhydride. Among these, it is most preferable to use maleic anhydride.

The amount of unsaturated carboxylic acid or its anhydride grafted onto the copolymer of vinyl chloride and vinyl acetate is from 0.01 to 5% by weight, preferably from 0.05 to 2% by weight.

The adhesive composition (AC agent) for the adhesive layer is:
Examples include formulations containing the above-mentioned graft polymer dissolved in a solvent such as an aromatic compound such as toluene or ethyl acetate, or an aliphatic compound, and these are stable at room temperature. Note that resins such as polyurethane and rubber may also be added to this adhesive composition.

In addition, the easily peelable resin used in the present invention includes:
Ethylene-vinyl acetate copolymer (hereinafter referred to as EVA)
system resin, ethylene-acrylic acid ester copolymer resin (
A tackifier is added to at least one of polyolefin resin (hereinafter referred to as EEA) and polyolefin resin, and these resins include the following.

A: Ethylene-vinyl acetate copolymer resin EVA (contains 15 to 35% by weight of vinyl acetate) Acid-modified EVA (E
(VA graft polymerized with unsaturated carboxylic acid or its anhydride) B Ethylene-acrylic ester copolymer resin EEA (acrylic ester content 5-25% by weight) C Polyolefin resin polyethylene (hereinafter referred to as PE) ) (low density PE, medium density PE, high density PE, linear low density PE), ethylene-
propylene copolymer, ethylene-butene-1 copolymer,
Atactic polypropylene, isotactic polypropylene, acid-modified polypropylene (unsaturated carboxylic acid or its anhydride graft polymerized to polypropylene), etc.D Tackifier rosin, rosin modified product, terpene resin, terpene modified resin, Compounds belonging to the above A, B, C, D such as aliphatic hydrocarbon resin, aromatic hydrocarbon resin, alicyclic hydrocarbon resin, etc. are one or two types in each group.
More than one species may be used in combination.

These compounds always contain component D, but for groups A and B, compounds from group C may or may not be used together, and for group C, either A or B may be used together. One or both may be used in combination, or may not be used together. In either case, component D is contained in an amount of 5 to 30% by weight, and component A is
It is also preferable that one or both of , B be 60 to 80% by weight and the balance be C, and it is also preferable that C be 50 to 60% by weight and the balance be either A or B or both.

An antioxidant, a slip agent, an antiblocking agent, etc. may be appropriately added to the above-mentioned easily peelable resin as an auxiliary agent.

The laminate according to the present invention is produced by applying the adhesive composition as an AC agent to a metal foil such as aluminum foil using a gravure printing machine, a coating device of a dry laminator, an anchor coating device of an extrusion laminator, a general lacquer coater, etc. Gravure gravure coating method, roll coating method, air knife coating method, dipping injection amount 0.001 to 1 by conventionally known methods.
It can be easily obtained by coating to a thickness of 1 μm, preferably 0.05 to 0.2 μm, and then extruding and laminating the easily peelable resin.

The laminate of the present invention can be produced by extruding and laminating the easily peelable resin immediately after applying the adhesive composition to the metal foil (in-line method), or by laminating only the easily peelable resin later ( (offline method) is also possible.

The thus obtained laminate of the present invention has strong adhesion between the metal foil and the easily peelable resin film, which have been difficult to adhere to in the past, and has excellent heat resistance.

The packaging material made of the laminate obtained by the present invention is used as a lid for a container, and the container body can be made of polypropylene (hereinafter referred to as PP), polyvinyl chloride (hereinafter referred to as PvC), polystyrene (hereinafter referred to as PvC), polystyrene (hereinafter referred to as PvC), , PS) or a composite laminate having a surface layer of these plastics is used. In particular, when a lid made of the laminate material of the present invention is used on a foamed polystyrene container body such as Kanpramen, even if the periphery is thermocompression-bonded to the periphery of the opening of the container body, it will fuse with the container body when the lid is opened. The attached releasable resin is easily peeled off.

This lid also peels off easily even after pouring boiling water into the container body and leaving it for a while.

This is because the AC agent has high adhesive strength and heat resistance.

〔Example〕

Next, the present invention will be explained in detail.

Example 1 A reaction product of 1% by weight of maleic anhydride and 99% by weight of polyvinyl chloride and vinyl acetate copolymer was adjusted to a 5% by weight solution with a mixture of toluene and ethyl acetate, and the resulting composition was extruded. To use as an AC agent for lamination, a piece of art paper (79.1g/rd) and aluminum foil (7μ
m) and low density polyethylene (MI-3, thickness Oμ
), and on the aluminum foil surface of the base material, the above AC agent was applied at a coating amount of 0.2 g/rrr using an AC agent coating device of an extrusion laminator (diameter: 40 mφ), and on top of that, the following easily peelable adhesive was applied. A laminate is prepared by extrusion coating the resin composition to a thickness of 30 μm.

Next, the bead expanded polystyrene container (PS container) and the lid made of the above laminate were heated at 180°C with a cup sealer.
Seal for 0.5 seconds at IKg/csi. Then, open the lid by 2 to 3 cm, fill the lid with boiling water from the opening up to the 5th crane, leave it for 5 minutes, peel off the rest of the lid, observe the condition, and report the results. Shown in 1.

(Composition of easily peelable resin composition) PR<Petrocene 203: Tosoh WFIJMI-8g/
10 minutes) 60% by weight EVA (Sumitate 1 (A-20: Vinyl acetate 20% by Sumitomo Chemical Co., Ltd.) 20% by weight Alicyclic hydrocarbon resin (Alcon P-90: Made by Arakawa Chemical Co., Ltd. Softening point (ring ball) Method) 90°C) 20% by weight Example Also, the results are shown in Table 1.

Comparative Example 1 A test was conducted in the same manner as in Example 1, except that an imine-based AC agent (EP Primer 108: Specially manufactured by Dainippon Ink and Chemicals) was used as the AC agent. The results are shown in Table 1.

Comparative Example 2 A test was conducted in the same manner as in Example 2, except that an imine-based AC agent (EP Brimer 108: Specially manufactured by Dainippon Ink and Chemicals) was used as the AC agent. The results are shown in Table 1.

Comparative Example 3 In Example 1, a polyolefin-based AC agent (
The test was conducted in the same manner except that DIC Seal AC-aoo (specially manufactured by Dainippon Ink and Chemicals) was used. 'The results are shown in Table 1.

Comparative Example 4 In Example 2, a polyolefin-based AC agent (
Dic Seal AC-300: Dainippon Ink & Chemicals ■
The test was conducted in the same manner, except that a sample (manufactured by A. The results are shown in Table 1.

Comparative Example 5 In Example 1, an isocyanate-based AC agent (
The test was conducted in the same manner except that LP-50OA/B (specially manufactured by Dainippon Ink and Chemicals) was used. The results are shown in Table 1.

Comparative Example 6 In Example 2, an isocyanate-based AC agent (
The test was conducted in the same manner except that LP-50OA/B (specially manufactured by Dainippon Ink and Chemicals) was used. The results are shown in Table 1.

Table 1 [Effects of the Invention] According to the present invention, an adhesive composition containing a resin obtained by graft polymerizing an unsaturated carboxylic acid or its anhydride to an ethylene-vinyl acetate copolymer resin is used as an AC agent to bond metals. Since we can provide a laminate in which a layer and an easily peelable resin layer are adhered, a lid using this as a packaging material can be sealed to a container body made of plastic or the like, and a part of it can be peeled off. ! Even after pouring hot water and leaving it for a while, the remaining part was separated by a ratio of 1:1, and the peeling was successful.This is because the AC agent has a strong adhesive force between the metal layer and the easily peelable resin layer. , 'I&' shows heat resistance that does not change depending on the temperature.

As a result, compared to current cup ramen lid materials,
Not only was it possible to simply further reduce the number of PE layers, but the number of material manufacturing steps was reduced by one step, making production more efficient.
It is possible to save labor and reduce costs.

August 23, 1999

Claims (2)

[Claims] (1) a metal layer, an adhesive layer containing a graft polymer obtained by reacting a vinyl chloride-vinyl acetate copolymer with an unsaturated carboxylic acid or its anhydride, and an ethylene-vinyl acetate copolymer-based resin; An easily peelable packaging material characterized by having a laminate in which easily peelable resin layers containing a resin made of at least one of an ethylene-acrylic acid ester copolymer resin and a polyolefin resin and a tackifier are sequentially laminated. laminate for use. (2) The tackifier is at least one selected from the group of rosin, rosin-modified resin, terpene resin, terpene-modified resin, aliphatic hydrocarbon resin, aromatic hydrocarbon resin, and alicyclic hydrocarbon resin. The easily peelable laminate for packaging material according to claim 1, characterized by: