JPS5818954B2 - Adhesive for dry lamination - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to vinyl acetate containing 10 to 30% ethylene and containing 5 to 30% (the same applies below by weight) of an epoxy compound.
The present invention relates to a water-based adhesive for dry lamination consisting of an ethylene copolymer dispersion and an amine-based epoxy curing agent.

In recent years, in the food packaging industry and elsewhere, bag products using multilayer laminate films with two or more layers have shown significant growth in both type and quantity.

This is due to the diversification of dietary habits, the spread of ready-to-eat foods and frozen foods, and the emergence of high-end, TL [foods] that satisfy advanced tastes, such as polyester, biaxially oriented nylon, biaxially oriented polypropylene, Unstretched polypropylene 1
．． This is due to the increase in high-performance plastic films, mainly high-density polyethylene.

Conventionally, extrusion lamination of cellophane and polyethylene has been the mainstream for multilayer films, but various lamination methods have been developed to meet the above-mentioned variety of films and advanced performance requirements. Among them, the dry lamination method allows arbitrary films to be laminated together. It has the great feature of being able to be laminated freely and producing high-performance packaging materials tailored to the purpose.

The adhesive for this dry lamination method is 2-2 dissolved in a solvent such as ethyl acetate, methyl ethyl ketone, or acetone.
Liquid-based urethane-based products are being praised, but the use of solvents poses major problems such as toxicity, flammability, and air pollution, and it is necessary to recover the solvents, which is extremely difficult. It is something.

These drawbacks can be improved by using an aqueous dispersion type adhesive, but there are very few ordinary aqueous dispersion type adhesives suitable for the dry laminating adhesive that is the object of the present invention.

There is no material that has particularly good adhesion to polyolefin films.

The present inventors have attempted to solve the above-mentioned drawbacks (as a result of various studies, we have developed a method in which an amine-based epoxy curing agent is used in combination with an aqueous dispersion containing an epoxy compound in a specific copolymer dispersion of vinyl acetate and ethylene). Not only does it have good adhesion in normal dry lamination, but it also has good adhesion when laminating plastic film on the printed surface, and since it is an aqueous dispersion, it is non-toxic and non-flammable. It has been found that this is an excellent water-based adhesive for dry lamination that is extremely easy to handle and has no concerns about pollution.

In the aqueous dispersion containing an epoxy compound in a copolymer dispersion of vinyl acetate and ethylene in the present invention, the vinyl acetate-ethylene copolymer dispersion is prepared by emulsifying vinyl acetate using an appropriate emulsifier and protective colloid, and polymerizing the dispersion. It is produced by an emulsion polymerization method in which ethylene is forced into a catalyst and copolymerized under pressure.

The copolymer dispersion is not limited to a vinyl acetate-ethylene copolymer dispersion, and a terpolymer dispersion containing 10% or less of the third component may be used.

The ethylene content of the vinyl acetate-ethylene copolymer in the dispersion needs to be 10 to 30%; if the ethylene content is lower than 10%, the water resistance of the adhesive will decrease and the adhesiveness to polyolefins will also be poor.

On the other hand, if the ethylene content exceeds 30%, the cohesive force of the adhesive decreases, resulting in poor adhesion.

The epoxy compound can be added to the vinyl acetate-ethylene copolymer dispersion in any suitable manner. For example, the epoxy compound may be added to the vinyl acetate-ethylene copolymer dispersion as it is or as an emulsion. There are methods such as dissolving a compound in a vinyl acetate monomer and carrying out emulsion polymerization to incorporate the compound.

The amount of the epoxy compound contained in the present invention is required to be 5 to 30% of the solid content of the vinyl acetate-ethylene copolymer resin, and if it is less than 5%, the adhesiveness to polyolefin will be poor, and it will not be suitable for dry lamination, which is the purpose of the present invention. Not suitable as an adhesive.

On the other hand, if the epoxy compound content exceeds 30%, the dispersion of the epoxy compound becomes poor and the dispersion liquid becomes highly viscous, which causes problems in production.

Furthermore, as the amount of epoxy compound increases, the heat resistance creep property deteriorates, and it is also unfavorable in terms of cost.

The epoxy compound used in the present invention is advantageously a low molecular weight compound with a relatively small epoxy equivalent, preferably an epoxy equivalent of 250 or less.

Examples of epoxy compounds include bisphenol A-epichlorohydrin type epoxy compounds, polyalkylene ether type epoxy compounds, side chain type epoxy compounds, alicyclic epoxy compounds, polymerized fatty acid ester type epoxy compounds, glyceryl triepoxide, alkylphenol type epoxy compounds, and novolak. There are type epoxy compounds, etc.

The vinyl acetate-ethylene copolymer dispersion containing the epoxy compound preferably has a resin solid content of 40 to 60%,
If it is less than 40%, the viscosity is low and workability is poor.

Also, since it contains a lot of water, it takes a long time to evaporate, resulting in poor productivity.

Moreover, if it exceeds 60%, the viscosity will increase and productivity will decrease.

The dry laminating adhesive of the present invention requires the use of an appropriate amount of an amine curing agent in the vinyl acetate-ethylene copolymer dispersion containing an epoxy compound to harden the epoxy compound. 100 parts of vinyl acetate-ethylene copolymer dispersion containing the compound (
(parts by weight), preferably 2 to 10 parts.

This amine-based epoxy curing agent includes, for example, aliphatic polyamines and their adducts such as diethylenetriamine, triethylenetetramine, monos thereof, and diepoxide adducts, heterocyclic amines and their adducts, dimer acid aliphatic polyamines and their adducts. , aromatic polyamines such as diphenyldiaminomethane or its monomer, and its adduct with diepoxide, and tertiary amines such as benzyldimethylamine.

For laminating with the aqueous dispersion according to the invention,
After adding an amine-based epoxy curing agent to a vinyl acetate-ethylene copolymer dispersion containing an epoxy compound, it is applied onto paper or plastic film, dried, and then bonded to another substrate material by thermocompression.

The resulting multilayer film includes, for example, a combination of films of low density and high density polyethylene, polyester, polypropylene, etc., and films of polyester, cellophane, nylon, vinylidene chloride resin, etc.

When laminating, if one of the substrate materials is porous, the applied water-based adhesive does not need to be dried (simply pressure bonding is sufficient, and it can also be applied to so-called wet lamination.

The conditions for dryer 5 lamination, such as the amount of water-based adhesive applied, drying temperature and time, pressure bonding force, pressure bonding temperature and time, are appropriately selected depending on the type, thickness, etc. of the substrate material.

In addition, when laminating on a polyolefin film, it is preferable to subject the film surface to corona discharge treatment, primer treatment, or the like.

Next, the present invention will be further explained with reference to Examples.
The content of the present invention is not limited thereby.

Example I A. Preparation of vinyl acetate-ethylene copolymer dispersion containing an epoxy compound 3.5 parts of polyvinyl alcohol with an average degree of polymerization of 500 and a degree of saponification of 92 mol % is added to 100 parts (parts by weight, hereinafter the same) of water. 1.5 parts of polyvinyl alcohol with an average degree of polymerization of 1700 and a degree of saponification of 84%, 0.01 part of sodium acetate dispersed therein, and 20 parts of a bisphenol A-epichlorohydrin type epoxy compound with an epoxy equivalent of 186 were mixed with vinyl acetate monomer. The mixture was dissolved in 80 parts and placed in an autoclave, and the temperature was raised to 60°C while stirring to emulsify.
Ethylene was pressurized until it reached kg/cwt.

Stirring was continued while maintaining the ethylene pressure of 40 kg/crA until the dissolving power of ethylene in vinyl acetate was saturated, and then a 10% Rongalite aqueous solution and a 6% ammonium persulfate aqueous solution containing 0.5% sodium acetate were added. was continuously added to initiate polymerization.

The pH of the system was maintained at 5 to 6 during the polymerization. Polymerization was carried out for 5 hours, and after confirming that the vinyl acetate monomer content was 0.5% or less, the polymerization was completed by cooling.

The resulting aqueous dispersion had a solid content of 55.2% and an average particle size of 0.
．． 8μ, viscosity 1860 cps (BL-60rpm,
(25°C), the content of epoxy compounds is 16.4% based on the resin solid content, and the content of vinyl acetate excluding epoxy compounds is
The ethylene composition was 82%-18%.

B. Preparation and Adhesion of Laminate Film Blend 5 parts of Shuamine 9000 (epoxy curing agent, aromatic polyamine manufactured by Showa Denko) as a curing agent to 100 parts of the aqueous dispersion as a curing agent to the aqueous dispersion prepared in A. Furthermore, 0.0% of Neoperex 0TP (wetting agent manufactured by Kao Soap) was added.
An adhesive was prepared by adding 1 part.

This adhesive was applied to a corona discharge treated low density polyethylene film (thickness 15μ) at a rate of 7j'/m'', dried at 80°C for 1 minute, and coated with nylon film (Kojin Bonyl, A laminate film was prepared by pressing a polyester film (Lumirror manufactured by Toshi Co., Ltd., thickness 12 μm) and curing it at 40° C. for 48 hours.

The adhesion was measured by cutting the laminate film into 2.5 cIrI@ and using an autograph (Shimadzu Type-100).

The results are shown in Table 1.

Example 2 A. Preparation of vinyl acetate-ethylene copolymer dispersion containing epoxy compound 1.5 parts of hydroxyethyl cellulose with 2.5 moles of ethylene oxide added to 100 parts of water, HLB 18.5
2. polyoxyethylene nonylphenol ether.
5 parts, 1.0 part of polyoxyethylene nonylphenol ether with HLB 14.3, 0.01 part of sodium acetate dispersed therein, 15 parts of bisphenol A-epichlorohydrin type epoxy compound with epoxy equivalent of 186, and 85 parts of vinyl acetate monomer. 40 parts out of a total of 100 parts of the solution was charged into an autoclave and heated to 50°C while emulsifying, and ethylene was pressurized until the concentration reached 50'q/crA.

Stirring was continued while maintaining the ethylene pressure of 50 kg/crux until the dissolution of ethylene in the vinyl acetate monomer reached saturation, and then 10% Rongalite aqueous solution and 4% potassium persulfate aqueous solution were continuously added to initiate polymerization. At the same time, the remaining epoxy compound/vinyl acetate monomer (60 parts) was added continuously over a period of 4 hours.

The pH of the system during polymerization was maintained at 5.5 to 6.5.

Polymerization was carried out for 6 hours, and after confirming that the residual vinyl acetate monomer was 0.5% or less, the polymerization was completed by cooling.

The resulting aqueous dispersion had a resin solid content of 53.9%, an average particle size of 0.7μ, and a viscosity of 860 cps (BL-60rp
The content of the epoxy compound was 9% based on the resin solid content, and the composition of vinyl acetate-ethylene excluding the epoxy compound was 80%-20%.

B. Creation and adhesion of laminate film The same procedure as in Example 1 was carried out.

The adhesive strength results are shown in Table 1.

Example 3 A vinyl acetate-ethylene copolymer dispersion containing an epoxy compound was prepared using Sumikaflex 400 (vinyl acetate-ethylene copolymer dispersion manufactured by Sumitomo Chemical, ethylene content 18
%) to bisphenol with an epoxy equivalent of 186 - shrimp chlorohydrin type epoxy compound to Sumikaflex 40
It was added in an amount of 10% based on the resin solid content of 0.

The preparation and adhesive properties of the laminate film were carried out in the same manner as in Example 1, and the results obtained are shown in Table 1.

Example 4 The same procedure as in Example 1 was conducted except that Sumicure MT-1 (an epoxy curing agent manufactured by Sumitomo Chemical, an aromatic polyamine-based modified product) was used instead of Shoamine 9000 used in Example 1.

The results are shown in Table 1.

Reference example 1 Solvent-based adhesive for dry lamination (2-component urethane type;
Adhesive strength was measured using EPS601 (manufactured by Dainippon Ink) on the same adherend and under the same bonding conditions as in Example 1.

The results are shown in Table 1. Reference Example 2 The same procedure as in Example 1 was conducted except that no epoxy compound was used when preparing the aqueous dispersion and no curing agent was used during lamination.

The results are shown in Table 1. Reference Example 3 The same procedure as in Example 1 was carried out except that the epoxy compound used in preparing the aqueous dispersion of Example 1 was changed to 3 parts and the vinyl acetate monomer was changed to 97 parts.

The results are shown in Table 1.

Example 5 5 parts of Shuamine 9000 (epoxy curing agent, aromatic polyamine manufactured by Showa Denko) was blended as a curing agent into the aqueous dispersion prepared in Example 1, and a 100μ thick sample was prepared by corona discharge treatment. Apply 517 crrt (as resin solid content) to high density polyethylene film and
After drying at 130°C, the nylon and polyester films used in Example 1 were heated at 130°C and weighed 4kg1c.
Laminated in seconds.

Adhesive force measurement was performed in the same manner as in Example 1.

The results are shown in Table 2. Example 6 Example 5 except that the aqueous dispersion prepared in Example 2 was used.
I did the same thing.

Claims (1)

[Claims] 1 Dry laminate consisting of an aqueous dispersion of a vinyl acetate-ethylene copolymer dispersion with an ethylene content of 10 to 30% by weight and an epoxy compound containing 5 to 30% by weight based on the copolymer, and an amine-based epoxy curing agent. Water-based adhesive.