JP2003138245A - Aqueous adhesive composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous adhesive composition especially suitable for an industrial adhesive, which has an excellent adhesion and resistance to water. SOLUTION: The aqueous adhesive composition comprises an ethylene acid copolymer (preferably containing >=15 wt.% acid copolymer), an ethylene/vinyl acetate copolymer and an isocyanate crosslinking agent. Preferably, the aqueous adhesive composition comprises >=5 pts.wt. ethylene acid copolymer against 100 pts.wt. ethylene/vinyl acetate copolymer and 2-20 pts.wt. isocyanate crosslinking agent against 100 pts.wt. total of the ethylene acid copolymer and the ethylene/vinyl acetate copolymer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a water-based adhesive composition, and more particularly to a water-based adhesive composition that is preferably used for bonding an olefin resin.

[0002]

2. Description of the Related Art In recent years, in the adhesive industry and the industry that uses adhesives, water is used in place of solvent-based adhesives that use organic solvents as a medium, from the viewpoints of safety for human bodies, fire prevention, environmental protection, etc. Water-based adhesives such as aqueous solution type or emulsion type adhesives, which are used as a medium, have attracted attention, and the amount of use thereof is increasing. Among water-based adhesives, emulsion-type adhesives containing acrylic resin or urethane resin as the main component are promising because they have better adhesive strength, heat resistance, water resistance, etc. than other water-based adhesives. ing.

On the other hand, industrial adhesives, which are the main applications of adhesives, are generally continuously used in factory lines, and move immediately after bonding to proceed to the next step, so that excellent initial adhesive strength is required. At the same time, it is finally necessary to exhibit high adhesive strength, heat resistance, water resistance and the like.

However, an ordinary urethane resin-based adhesive generally has an insufficient initial adhesive force, and rarely an adhesive which exhibits a good initial adhesive force has a poor progress in adhesive force over time. There are drawbacks such as insufficient final adhesive strength, heat resistance, water resistance, etc., and the performance as the industrial adhesive is not sufficiently satisfied. Further, an adhesive made of an acrylic resin also has a drawback that the heat-resistant creep performance is inferior.

[0005]

DISCLOSURE OF THE INVENTION The present invention solves the problems of the above-mentioned conventional water-based adhesives, and therefore has both excellent adhesive strength and water resistance, and is particularly suitable as an industrial adhesive. The purpose is to provide things.

[0006]

To achieve the above object, the present invention according to claim 1 comprises an ethylene acid copolymer, an ethylene-vinyl acetate copolymer and an isocyanate crosslinking agent. An aqueous adhesive composition is provided. Further, the present invention according to claim 2 provides the water-based adhesive composition according to claim 1, wherein the acid content of the ethylene-based acid copolymer is 15% by weight or more. Further, the present invention according to claim 3 is the water-based adhesive composition according to claim 1 or 2, wherein the ethylene-based acid copolymer is contained in an amount of 5 parts by weight or more based on 100 parts by weight of the ethylene-vinyl acetate copolymer. Provide things. The present invention according to claim 4 further comprises 2 to 20 parts by weight of an isocyanate crosslinking agent based on 100 parts by weight of the total of the ethylene acid copolymer and the ethylene-vinyl acetate copolymer. Item 3. An aqueous adhesive composition according to any one of items 1 to 3.

The present invention will be described in more detail below. The water-based adhesive composition of the present invention is generally produced by mixing a water-soluble ethylene acid copolymer, an ethylene-vinyl acetate copolymer emulsion, and an isocyanate cross-linking agent. Used.

The ethylene-based acid copolymer in the present invention is a copolymer of ethylene and an acid, and may be a copolymer of other copolymerizable monomer, if necessary. The acid content of the ethylene-based acid copolymer is preferably 15% by weight or more, more preferably 20% by weight or more. When the content of the acid is less than 15% by weight, it may be difficult to disperse the ethylene acid copolymer in water. In addition, the above-mentioned water dispersion means being uniformly dispersed in water, and does not have to be completely dissolved into a transparent solution. The acid is not particularly limited as long as it is a copolymerizable organic acid, and preferably has a carboxyl group, for example, acrylic acid, methacrylic acid,
Examples thereof include itaconic acid.

In addition, the above ethylene-based acid copolymer includes
A compound containing a functional group having an active hydrogen atom capable of reacting with an isocyanate described below may be copolymerized. The type of such a compound is not particularly limited, but examples thereof include a compound having a functional group capable of reacting with an isocyanate group such as a hydroxyl group or a primary or secondary amine.

The ethylene-vinyl acetate copolymer in the present invention is a copolymer of ethylene and vinyl acetate, and is further copolymerized with another copolymerizable monomer, if necessary. May be. The ethylene content in the ethylene-vinyl acetate copolymer is preferably 15 to 35% by weight. If it is less than 15% by weight, the adhesiveness may be lowered, and if it exceeds 35% by weight, it may be difficult to stably obtain it as an industrial product. The ethylene-vinyl acetate-based copolymer is usually used in the form of an ethylene-vinyl acetate-based copolymer emulsion.

In the water-based adhesive composition of the present invention, the blending amount of the ethylene-based acid copolymer and the ethylene-vinyl acetate-based copolymer is 100 parts by weight of ethylene-vinyl acetate-based copolymer. 5 type acid copolymer
It is preferable to add more than 20 parts by weight, more preferably 20 to 60 parts by weight. If the addition amount is less than 5 parts by weight, the adhesiveness may be low.

The water-based adhesive composition of the present invention contains an isocyanate cross-linking agent, and the addition amount is not particularly limited as long as it can improve the adhesiveness, and preferably an ethylene-based acid copolymer and an ethylene-based adhesive are used. The isocyanate crosslinking agent is 2 to 20 parts by weight, and more preferably 5 to 10 parts by weight, based on 100 parts by weight of the total amount of the vinyl acetate copolymer. If the addition amount is less than 2 parts by weight, the water resistance may be poor, and if the addition amount is more than 20 parts by weight, the curing speed may be increased and the usage time of the adhesive may be too short.

The above-mentioned isocyanate-based cross-linking agent is not particularly limited as long as it has two or more isocyanate groups in the molecule, and examples thereof include polyols such as trimethylolpropane and pentaerythritol, and toluene diisocyanate and diphenylmethane diisocyanate. , Polyisocyanates such as hexamethylene diisocyanate, isocyanate prepolymers obtained by reacting under conditions of excess isocyanate groups,
It is preferably used. The above isocyanate crosslinking agents may be used alone or in combination of two or more kinds.

(Function) Since the water-based adhesive composition of the present invention contains an ethylene-based acid copolymer, an ethylene-vinyl acetate-based copolymer, and an isocyanate-based crosslinking agent,
It is possible to impart the adhesiveness between the olefin resin and the polyurethane foam and the water resistance after the adhesion.

[0015]

EXAMPLES The present invention will be described in detail by describing Examples and Comparative Examples below. (Example 1) Ethylene acrylic acid copolymer (hereinafter referred to as E
Say AA. Mitsui DuPont Polychemical Co., Ltd., trade name “Nucrel 5130H”, acrylic acid content 20% by weight) was neutralized with ammonia and then dissolved at 90 ° C. to prepare a 25% by weight EAA aqueous solution. 50 parts by weight of this EAA aqueous solution in terms of resin and ethylene-vinyl acetate copolymer emulsion (hereinafter referred to as EVA emulsion, manufactured by Kuraray Co., Ltd., trade name "OM-4000", ethylene content 18% by weight) EVA. 10 in terms of emulsion resin
0 parts by weight were compounded. Furthermore, the above EAA aqueous solution and E
The isocyanate cross-linking agent "Coronate L-4" was added to 100 parts by weight of the resin solution of the mixed solution of the VA emulsion.
5 "(solid content 45% by weight, manufactured by Nippon Polyurethane Industry Co., Ltd.) was mixed to prepare an aqueous adhesive composition. Below, E
The weight descriptions of the VA emulsion and the EAA aqueous solution are all the values converted into the resin content.

(Example 2) An aqueous adhesive resin composition was obtained in the same manner as in Example 1 except that the mixing ratio was 100 parts by weight of EVA emulsion and 10 parts by weight of EAA aqueous solution.

Comparative Example 1 An aqueous adhesive composition was obtained in the same manner as in Example 1 except that isocyanate was not used.

(Performance Evaluation) The obtained water-based adhesive composition was evaluated for performance by the following method.

1) T-type peeling measurement (adhesive strength measurement) As an adherend, a non-woven fabric laminated with a 0.1 mm thick polyethylene film cut into a width of 50 mm and a length of 100 mm and a polyurethane foam (foaming ratio: 30 times) On the other hand, the water-based adhesive is applied so that the coating amount (wet) of the water-based adhesive composition is 45 g / m ² over 5 cm from the end of the adherend (the polyethylene laminated surface when a nonwoven fabric laminated with a polyethylene film is used) After applying the composition, the other adherend was adhered onto the water-based adhesive composition under the condition of reciprocating twice with a manual roll (press bonding at a pressing pressure of 15.7 kPa) to prepare an adhesion test piece. After curing this adhesion test piece for 72 hours in an atmosphere of 20 ° C. and 65% RH, a tensile tester (trade name “Instron 119
5 ", manufactured by Instron Co., Ltd.)
A tensile test was conducted at m / min to measure the adhesive force (kPa). In addition, the area where the polyurethane foam was cohesively broken and adhered to the polyethylene film side was evaluated as a material break.

2) Aged T-type peeling adhesive strength After the prepared water-based adhesive composition was left at room temperature for 6 hours,
An adhesion test piece was prepared in the same manner as in 1), and T-type peeling measurement was performed.

3) Water-resistant adhesion The adhesion test piece prepared in the same manner as in 1) was immersed in warm water at 70 ° C for 2 hours, dried at 60 ° C for 3 hours, and the peeled state was visually observed. The evaluation results of 1) to 3) above are shown in Table 1. In the T-type peeling measurement of Comparative Example 1, interfacial peeling was remarkable.

[0022]

[Table 1]

[0023]

The water-based adhesive composition of the present invention contains an ethylene-based acid copolymer, an ethylene-vinyl acetate-based copolymer, and an isocyanate-based cross-linking agent. , A water-based adhesive suitable for use as an industrial adhesive capable of discovering high water resistance after aging, and having excellent water resistance and heat resistance even though it is a water-based adhesive composition A composition can be provided. From the above, for example, when the polyethylene film and the polyurethane foam are adhered by the adhesive composition of the present invention, sufficient adherence is exhibited without the adherends being displaced from each other on the adhering surface. It is possible to obtain a large adherend.

Claims (4)

[Claims] 1. A water-based adhesive composition comprising an ethylene-based acid copolymer, an ethylene-vinyl acetate-based copolymer, and an isocyanate-based cross-linking agent. 2. The acid content of the ethylene-based acid copolymer is 1
The water-based adhesive composition according to claim 1, which is 5% by weight or more. 3. An ethylene-vinyl acetate copolymer 100
The water-based adhesive composition according to claim 1 or 2, wherein the ethylene-based acid copolymer is contained in an amount of 5 parts by weight or more based on parts by weight. 4. The total amount of the ethylene-based acid copolymer and the ethylene-vinyl acetate-based copolymer is 100 parts by weight,
The water-based adhesive composition according to any one of claims 1 to 3, wherein the isocyanate-based crosslinking agent is contained in an amount of 2 to 20 parts by weight.