JPS59217780A - Adhesive composition - Google Patents

Abstract

PURPOSE:An adhesive composition having suppressed foaming and rise in viscosity, showing improved workability, having improved bond strength and water resistance obtained by blending an aqueous emulsion containing acetoacetylated polyvinyl alcohol with an isocyanate compound. CONSTITUTION:An aqueous emulsion (e.g., vinyl acetate emulsion, etc.) containing an acetoacetylated polyvinyl alcohol (preferably one containing 1-10mol% a cetoacetyl group, having 0.1-15mol% remaining hydroxyl group, and 500-2,600 degree of polymerization) is blended with preferably 0.1-15wt% isocyanate compound (e.g., tolyene diisocyanate, diphenylmethane diisocyanate, etc.), to give the desired composition.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an adhesive composition comprising an aqueous emulsilone (isocyanate base) compound having excellent adhesive strength and water resistance.

Water-based emulsion-isocyanate compound adhesives have been widely used in recent years, but the crystal binders used are mainly water-based and are almost mutually soluble with water. isocyanate-based compounds (polymerized products) in a solvent that has mutual solubility with isocyanate-based compounds (polymerized products).
The curing agent was prepared by dissolving it. If an isocyanate compound (polymer) is directly mixed into an aqueous emulsion using this solvent, the reaction will be violently reversed, resulting in significant foaming and thickening of the adhesive, resulting in poor workability during use. However, these problems have been solved by suppressing the reaction by diluting with a solvent. Although improvements have been made by using solvents, there have been problems with organic solvents, such as fire hazards, odors, and other problems, as well as performance problems such as a decrease in initial adhesive strength.

The present invention was studied to solve this problem, and it was found that an adhesive composition made of aqueous emulsilon and isocyanate F compound (polymer) using special polyvinyl alcohol does not cause this problem. .

To explain in detail below, we refer to acetoacetate A/PVA obtained by reacting diketene to the special polyvinyl alcohol μ alcohol A/(hereinafter referred to as PvA) and the reaction formula is OHOHO-C=0 C=O CH2C =O CH8' The PVA used has a carboxy μ group, an amide group,
P modified with a small amount of nitro group, force μ acid ester group, etc.
VA is also included. Acetoacetymu-ization pvAQ Average degree of saponification and average degree of polymerization are not particularly limited, but are preferably in the range of 0.1 to 15 mol% of residual hydroxyl groups and average degree of polymerization of 500 to 2,600 ^ The content of acetoacetyl groups is 0 .05～
A range of 15 mol% and preferably 1 to 10 mol% is appropriate; below 0.05 mol L/%, the contribution to the water resistance, stability, and thickening properties of the emulsion is small and undesirable.
If it exceeds 5 mol%, it is difficult to obtain a homogeneous emulsion.

To create an aqueous emulsion using the acetoacetylated PVA, use the acetoacetylated PVA as an emulsifier or protective colloid. - Emulsion polymerization. A synthetic resin liquid is added and emulsified in the presence of the acetoacetylated PVA. A method such as adding the acetoacetylated PVA to an existing synthetic secondary fat emulsion to form an aqueous emulsion is adopted. Specific examples of the aqueous emulsion include:
Vinyl acetate emulsion, vinyl acetate emulsion (
Ethylene-vinyl acetate emulsion, copolymerization emulsion of vinyl acetate with unsaturated acids such as acrylic acid, maleic acid, fuma/l/acid, crotonic acid, and their esters, etc.) acrylic emulsion (acrylic acid ester emulsion, There are acrylic acid ester-styrene co-filled emulsions, etc.) Styrene-butadiene copolymer latex, butadiene-acrylontrile copolymer latex, chloroprelate latex, butyl rubber latex, and polybutadiene latex. The acetoacetylated P
The amount of VA to be used may be adjusted depending on the emulsion solid content, emulsion composition (ratio), viscosity, degree of acetoacetylation, etc., but under general usage conditions it is 0.1 to 10.
Compatible with uP/1rlrE.

TDI when used as a hardening agent for the aqueous emulsion
Examples include () lylene diisocyanate), hydrogenated TDT,) rimethylol provalet TDT adduct, triphenylmethane triisocyanate, di/phenylene diisocyanate (MDI), quinoles diisocyanate, and the like. That praise (, polio)
An isocyanate prepolymer obtained by mixing μ with an excess of polyisocyanate and reacting the mixture may also be used.

The amount of the isocyanate composition added to the aqueous emulsion is 0.1 to 1.5 vrt'10. The amount to be added may be determined by taking into account the working temperature, the time of use of the adhesive, and the degree of thickening of the compound.

The adhesive composition may be used as a mixture of only the base agent and the curing agent, but it may also be used as a mixture of S-Teden powder, CAC (HEC containing carboxymethyl cellulose (and droxyethyl cellulose)), carbonic acid, schrum, talc, mica, etc. Bulking agents may also be used.

Although it is not clear how the use of gpvA can achieve the same effects as conventionally used solvents, the acetoacetyl group is responsible for the steric reaction between the hydroxyl group and the isocyanate group in the PVA. It is presumed that the problem □ of foaming, thickening, etc., which becomes a hindrance and has a reaction suppressing effect, will be resolved.

Hereinafter, this will be specifically explained in Examples.

Example 1 Acetoacetylated poval 5gQ water 60su! J@ was added and dissolved at 80° C. for 2 hours to obtain a protective colloid. Next 8
Hydrogen peroxide 0.2fC in protective colloid heated to 0℃
Using 0.05 g of 1-tartaric acid as an initiator, 35 g of vinyl acetate was added dropwise over 3 hours to form an emulsion by the conventional method 1. Furthermore, 1.5 g of Djibouti μ Phthalate (DBP) was added as a plasticizer to give a solid content of 41% and a viscosity of 5.
A vinyl acetate A/resin emulsion of 0.000'pa/30''C was obtained.

To 232,100 parts of the emulsion was added 10 parts of Millione) MR (MDI isocyanate yarn polymer manufactured by Nippon Polyurethane) to prepare an adhesive.

Comparative Example-2 Completely saponified polyvinyl alcohol/L/15g with 70g of water
To this solution, 50 g of SBR latex and 40 g of Lucium carbonate were added and mixed to give a solid content of 45% and a viscosity of 20.000.
A composition of cp/30°C was obtained.

To 100 parts of the composition, 10 parts of Millione) MR (MDI isocyanate polymer manufactured by Nippon Polyurethane) was added to prepare an adhesive.

Example-2 15 g of acetoacetylated poval was added to 60 g of water and dissolved in 801: for 2 hours to obtain a polymer aqueous solution.
100 g of R latex and 1.5 g of thickener were added to give a solid content of 36% and a viscosity of 20. A composition with OOOcl)/3) was obtained. Millionaire) MR (Nippon Boliu V)
Tanfitl1MDI isocyanate polymer) 10
g was added to prepare an adhesive.

The comparison results of the viscosity increase over time and adhesive performance of the above adhesives are shown in Table-
1. It was as shown in Table-2.

Table - 130°C increase in viscosity over time Note) 0: No foaming Δ: Foaming (slight) x: Severe foaming -: Nigel Table 2 Adhesive performance (Note) Test method Normal adhesion according to JTSK-6804.

Compression of birch wood x birch wood after 7 days breaking strength Hot and cold water adhesive crab JTSK-6801.

Birch wood x birch wood 78 after 60 Compression memory after soaking for f3 hours in 3 Strength Repeated boiling adhesive crab JISK-6802.

Birch wood x birch wood boiled after 7 days 60 after immersion in aqueous humor for 4 hours Dry at 3°C for 20 hours, Soak again in boiling water for 4 hours Post-compression shearing force Patent applicant: Aikanigyo Co., Ltd.

Claims (1)

[Claims] Acetoacetyl (contains 4 hinibo V vinyl μ apcol)