JP2006036878A - Aqueous adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an aqueous adhesive composition having an excellent width of a range applicable to an adherent, slightly containing a VOC (volatile organic compound), slightly emitting smell, and having excellent storage stability, creep resistance at high temperature, waterproof adhesive properties, adhesive properties at low temperatures and cold-proof adhesive properties. <P>SOLUTION: This aqueous adhesive composition comprises (A) a copolymer emulsion composed of a vinyl acetate and other ethylenically unsaturated monomers, and (B) an alkylene glycol benzoate, and has ≤-20°C glass transition temperature. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an adhesive composition having a low VOC excellent in adherence width, adhesion durability, and economy, and in particular, wood boards such as plywood, wood fiber board, and particle board used for various building materials. It is also used to bond inorganic boards such as slate boards and gypsum boards to plastic films made of polyvinyl chloride, polyolefin materials, etc. -It relates to a water-based adhesive composition having excellent properties.

In recent years, low VOC adhesives have been developed for the purpose of improving the working environment and reducing harmful chemical substances released from adhesive products. However, low VOCs for adhesives made of plastic materials are the storage stability of adhesives. Performance, adherence width, adhesion durability, etc. are not satisfied at the same time, and are still insufficient.
For example, as a relatively low VOC plastic film adhesive that does not use toluene / xylene with excellent adhesion durability, a vinyl acetate / ethylene copolymer resin emulsion (hereinafter abbreviated as EVA emulsion), an anionic polyurethane emulsion, and a specific adhesive Adhesives composed of high-boiling solvents (film-forming aids) are known (Patent Documents 1 and 2).
However, all of the high-boiling solvents used in these are easily hydrolyzed, so that the pH is greatly lowered during storage, and problems such as viscosity change and separation / sedimentation are likely to occur. There is also a problem that the odor of the solvent is strong.
By using a high gel content, low Tg EVA emulsion, an anionic polyurethane emulsion, and a water-insoluble hexamethylene diisocyanate polyisocyanate having an isocyanurate skeleton as a crosslinking agent without adding a film-forming aid. Although a method for lowering the VOC has been proposed (Patent Document 3), the suitability width of the adherend is not always sufficient, for example, the soft PVC film cannot be bonded.

JP-A-11-209722 JP 2002-60712 A JP 2003-64333 A

  It is an object of the present invention to overcome the lack of any of the storage stability of the adhesive, the applicable width of the adherend, and the durability of the adhesive due to the low VOC in these conventional technologies. It is an object of the present invention to provide an adhesive composition that satisfies all of the above requirements.

As a result of intensive studies, the inventors of the present invention have (A) a copolymer emulsion of vinyl acetate and other ethylenically unsaturated monomers, and (B) an alkylene glycol benzoate having a glass transition temperature of It has been found that an aqueous adhesive composition characterized by a temperature of −20 ° C. or lower is suitable for the intended purpose.
Further, it comprises (A) a copolymer emulsion of vinyl acetate and other ethylenically unsaturated monomers, (B) an alkylene glycol benzoate ester, and (C) an anionic polyurethane emulsion, and has a glass transition temperature of −20. It has been found that an aqueous adhesive composition characterized by a temperature of 0 ° C. or lower is more preferable and suitable for the intended purpose.
Said (A), (B), (C) is (B) with respect to 100 parts by mass (solid content) of a copolymer emulsion of (A) vinyl acetate and other ethylenically unsaturated monomers. It is preferable to blend 1 to 20 parts by mass of an alkylene glycol benzoate ester and 2 to 50 parts by mass (solid content) of (C) an anionic polyurethane emulsion.
Furthermore, when it is going to obtain high heat-resistant creep performance and water resistance performance, organic polyisocyanate and polyamide are used for the components (A) and (B) or the components (A), (B) and (C). It is preferable to contain or blend one or more selected from polyamine epichlorohydrin resins and oxazoline group-containing polymers.

  The water-based adhesive composition of the present invention is excellent in adherend application width, low VOC and low odor, and excellent in storage stability. Moreover, this water-based adhesive is excellent in heat-resistant creep performance, water-resistant adhesion performance, low-temperature adhesion performance, and cold-resistant adhesion performance.

  The aqueous adhesive composition of the present invention comprises (A) a copolymer emulsion of vinyl acetate and other ethylenically unsaturated monomers, (B) an alkylene glycol benzoate, and (C) anionic An adhesive comprising a polyurethane emulsion, and more preferably composed of one or more selected from organic polyisocyanate, polyamide polyamine epichlorohydrin resin, and oxazoline group-containing polymer. The glass transition temperature of the composition is −20 ° C. or lower.

Other ethylenically unsaturated monomers copolymerized with vinyl acetate in component (A) include ethylene, propylene, styrene, vinyl chloride and vinyl esters other than vinyl acetate, acrylic acid, butyl acrylate, acrylic An acrylic acid ester such as 2-ethylhexyl acid, and a methacrylic acid ester such as methyl methacrylate and 2-hydroxyethyl methacrylate can be used.
The copolymer emulsion of vinyl acetate and other ethylenically unsaturated monomers plays a role in obtaining adhesive strength and heat resistance, and is not particularly limited. For example, as illustrated below You can use anything.
As the vinyl acetate-ethylene copolymer emulsion, Sumikaflex S-305, S-400, S-400HQ, S-401, S-450, S-450HQ, S-455, S-455HQ manufactured by Sumitomo Chemical Co., Ltd. S-456, S-460, S-467, S-7400, S-473, S-480, S-500, S-510, Kuraray Panflex OM-4000, OM-4200, OM- 28, OM-5000, OM-5010, OM-2000, OM-3100, OM-3300, OM-3400, Denka EVA tex 60, Denka EVA tex 56, Denka EVA tex 65, Denka EVA, manufactured by Denki Kagaku Kogyo Co., Ltd. Tex 68 and the like. Examples of the vinyl acetate / acrylic acid ester copolymer emulsion include VW-P-101 and VW-P-131 manufactured by Hornen Corporation. Examples of the vinyl acetate / ethylene / VEOVA copolymer emulsion include Sumikaflex S-951 manufactured by Sumitomo Chemical Co., Ltd.

Alkylene glycol benzoate has a role of lowering the glass transition temperature and elastic modulus of the adhesive film, improving the adhesion with a hardly adhesive film, and improving the low temperature characteristics.
Examples of the alkylene glycol benzoate include ethylene glycol monobenzoate, ethylene glycol dibenzoate, propylene glycol monobenzoate, propylene glycol dibenzoate, diethylene glycol monobenzoate, diethylene glycol dibenzoate, and the like. It is done. These may be used alone or in admixture of two or more, but in particular, a mixture of ethylene glycol monobenzoate and ethylene glycol dibenzoate is optimal.
The blending amount of alkylene glycol benzoate is 1 to 20 parts by mass (solid content), preferably 100 parts by mass (solid content) of a copolymer emulsion of vinyl acetate and other ethylenically unsaturated monomers. Is 5 to 15 parts by mass.

An anionic polyurethane emulsion is a component used in order to express adhesiveness with a plastic film.
The anionic polyurethane emulsion used in the present invention is not particularly limited as long as it is usually used in this kind of field.
However, since anionic polyurethane emulsions often gel in the acidic region, poly (ethylene-vinyl acetate) copolymerization is usually used when using an anionic polyurethane emulsion that gels in such an acidic region. An anionic polyurethane emulsion that is gelled in an acidic region after being neutralized with a neutralizing agent is mixed.
However, when this is done, excess neutralizing agent tends to cause a reduction in heat-resistant creep performance. Further, the poly (ethylene-vinyl acetate) copolymer emulsion neutralized by the neutralizing agent becomes an acidic region again by hydrolysis, and the adhesiveness tends to be lowered. Therefore, from the viewpoint of adhesive performance and storage stability, the anionic polyurethane emulsion is preferably a sulfonic acid-modified one having high stability in the acidic region.

The sulfonic acid-modified anionic polyurethane emulsion refers to an emulsion having a sulfonate group in a urethane polymer molecule and usually emulsifying and stabilizing as a sulfonate salt.
The amount of the anionic polyurethane emulsion is 2 to 50 parts by mass (solid content), preferably 100 parts by mass (solid content) of a copolymer emulsion of vinyl acetate and other ethylenically unsaturated monomers, preferably 5 to 30 parts by mass.

The solid content concentration of the anionic polyurethane emulsion is 20 to 60% by mass, and more preferably 35 to 55% by mass from the viewpoints of workability and mechanical stability.
Preferable specific examples of the anionic polyurethane emulsion include, for example, Uprene UXA3004, UXA-3005, UX-306 manufactured by Sanyo Chemical Co., Ltd., Hydran HW-111, HW-333, HW- manufactured by Dainippon Ink & Chemicals, Inc. 311, HW-350, HW-337, AP-20, AP-60LM, AP-80, Dai-Kogyo Seiyaku Co., Ltd. Superflex 107M, 110, 126, 130, 150, 160, 300, 361, 370, 410, 460, 700, 750, 820, Dispacol U-42, U-53, U-54, KA-8484, KA-8484, etc. manufactured by Sumitomo Bayer Urethane Co., Ltd.

  For example, when used for flooring around water, JAS1 performance is required. When such high heat-resistant creep performance and water-resistant performance are to be obtained, the composition of the present invention is added to an organic polyisocyanate. One or two or more selected from the group consisting of a polyamide polyamine epichlorohydrin resin and an oxazoline group-containing polymer are contained or blended. These are preferably used in the range of 0.5 to 20% by mass in the composition with respect to 100 parts by mass of the solid content of the composition. If it is less than 0.5% by mass, high heat-resistant creep performance and water resistance cannot be obtained, and if it exceeds 20% by mass, the cost becomes high.

Any known organic polyisocyanate can be used here. For example, polymethylene polyphenyl polyisocyanate (polymeric MDI), burette-type trimer of hexamethylene diisocyanate, isocyanurate-type trimer of hexamethylene diisocyanate, trimethylolpropane adduct of hexamethylene diisocyanate, etc. can be used. .
The polyamide polyamine epichlorohydrin resin is a water-soluble resin obtained by reacting an epichlorohydrin with a polyamide polyamine resin. For example, Kaimen S-25 manufactured by Dick Hercules can be used.
The oxazoline group-containing polymer refers to a polymer obtained by copolymerizing an acrylic monomer having an oxazoline group, and for example, Nippon Shokubai Epocross WS-500 and Epocross WS-700 can be used.
It is essential that the glass transition temperature of the blended adhesive composition is −20 ° C. or lower. Glass transition temperature here refers to what is measured as a transition point of specific heat using differential thermal analysis (DSC).

The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples.
(Measurement of glass transition temperature)
The blended adhesive composition is taken in an aluminum cell, dried in a desiccator for 24 hours, then applied to a DSC manufactured by Mac Science, and the temperature is raised from −50 ° C. to 150 ° C. at a rate of 2 ° C./min, and the specific heat changes. The starting point was determined and used as the glass transition point.

(Adhesion performance test)
[Preparation of test piece]
The production atmosphere was N) 23 ° C., 50% RH, or L) 5 ° C. A medium fiberboard (MDF) (manufactured by Hokushin Co., Ltd., E0 type) was used as the substrate, and a 0.06 mm thick polypropylene film (adhesion surface primer treatment) was used as the adherend.
First, the adhesive produced in the following Examples and Comparative Examples is applied to a substrate at about 80 g / m ² with a roll coater. Next, the adherend is deaerated using a laminator on the substrate coated with the above adhesive, and then bonded and cold-pressed at 0.2 MPa for 30 minutes. The obtained adherend-bonded product is cut into a width of 25 mm to obtain a test piece.
[Normal adhesion test]
As a test piece, a test piece produced in the production atmosphere of N) was used, and the peel strength of this test piece was measured. That is, in an atmosphere of 23 ° C. and 50% RH, the 180 ° angular tensile adhesive force of the adherend was measured at a pulling rate of 100 mm / min using a shopper type tester to determine the peel strength.

[Heat resistant creep test]
As a test piece, a test piece produced in the production atmosphere of N) was used. A part of this test piece was peeled off, and a static load of 4.9 N was applied to the peeled surface in the 90-degree angle direction to perform A) and B) tests.
A) Test: The test was allowed to stand for 1 hour in a hot air circulating dryer set at 60 ° C. The length of peeling of the adherend after 1 hour was measured.
B) Test: It was allowed to stand for 24 hours in a hot air circulation dryer set at 70 ° C. The length of peeling of the adherend after 24 hours was measured.

[Low temperature adhesion test]
As a test piece, a test piece prepared in the preparation atmosphere of L) was used. This test piece was peeled off by a method in which the adherend was peeled off by hand in an atmosphere of 5 ° C. At that time, the fracture state of the peeled portion was visually observed and evaluated in the following three stages.
A: The base material was causing material destruction.
B: Cohesive failure was caused.
C: Interfacial destruction occurred.

[Cold resistance test]
As a test piece, a test piece prepared in the preparation atmosphere of L) was used. This test piece was allowed to stand at −20 ° C. for 24 hours, and then the adherend was instantaneously peeled by hand in an atmosphere at −20 ° C. At that time, the fracture state of the peeled portion was visually observed and evaluated in the following three stages.
A: The base material was causing material destruction.
B: Cohesive failure was caused.
C: Interfacial destruction occurred.

[JAS1 immersion peeling test]
As a test piece, a test piece obtained by cutting an adherend-bonded product prepared in the working atmosphere of N) into 75 mm × 75 mm was used. The obtained test piece was immersed in boiling water for 4 hours → dried in 60 ° C hot air circulating dryer for 20 hours → immersed in boiling water for 4 hours → dried in 60 ° C hot air circulating dryer for 3 hours, and then peeled off. Observed and evaluated in the following three stages.
○: No peeling △: Stripping less than 25mm (pass)
X: peeling larger than 25 mm (failed)
[Storage stability test]
The obtained aqueous adhesive composition was put into a 200 g glass bottle, sealed, and then left in a 40 ° C. incubator for 3 months to examine changes in pH and appearance.

(Raw materials used)
Product names and abbreviations used as raw materials for adhesives are shown below.
Component (A): Sumikaflex S-455HQ (abbreviation: EVA1) manufactured by Sumitomo Chemical Co., Ltd. (ethylene / vinyl acetate / polyfunctional monomer = 20/80 / 0.5 (weight ratio), toluene insoluble content: 90 wt. %, Glass transition point 0 ° C)
Sumitomo Chemical Co., Ltd., SUMIKAFLEX S-410 (abbreviation: EVA2) (ethylene / vinyl acetate / polyfunctional monomer = 30/70/1 (weight ratio), toluene insoluble matter 90% by weight, glass transition point- 18 ℃)
(B) Component / abbreviation EGB: Benzoic acid ethylene glycol ester (mixture of mono- and diesters)
Abbreviation BB: n-butyl benzoate Abbreviation DBE: Mixture of dimethyl adipate, dimethyl succinate and dimethyl glutarate Abbreviation BCA: monoacetic acid ester of diethylene glycol Abbreviation TEX: 2,2,4-trimethylpentane-1 , 3-diol monoisobutyrate, abbreviation TEXD: 2,2,4-trimethylpentane-1,3-diol diisobutyrate (C) component, abbreviation PUD: manufactured by Sumitomo Bayer Urethane Co., Ltd., DISPARALL KA-8484 (Anionic polyurethane emulsion with sulfonate group in the molecule)
(D) Component / abbreviation PI: Sumitur N3200, manufactured by Sumitomo Bayer Urethane Co., Ltd.
・ Abbreviation PAAE: Dick Hercules Kaimen S-25
-Abbreviation OX: Nippon Shokubai Epochros WS-500

(Examples 1-3, Comparative Examples 1-7)
Components (A) to (C) described in Table 1 were mixed in the parts by weight (solid content) described in Table 1 to prepare an adhesive. Using the obtained adhesive, a glass transition point, a normal adhesion test, a heat-resistant creep test, a low-temperature adhesion test, and a storage stability test were performed according to the above-described methods. The results are shown in Table 1.

(Examples 4-9, Comparative Examples 8-9)
Components (A) to (C) described in Table 2 were mixed in the parts by weight (solid content) described in Table 2 to prepare an adhesive. Using the obtained adhesive, a glass transition point, a normal adhesive strength test, a heat-resistant creep test, a low-temperature adhesiveness test, a cold-resistant adhesiveness test, a JAS1 immersion peeling test, and a storage stability test were performed according to the above-described methods. . The results are shown in Table 2.

Claims (4)

  (A) A copolymer emulsion of vinyl acetate and another ethylenically unsaturated monomer, and (B) an alkylene glycol benzoate, having a glass transition temperature of −20 ° C. or lower. Water-based adhesive composition.   (A) A copolymer emulsion of vinyl acetate and other ethylenically unsaturated monomers, (B) an alkylene glycol benzoate ester, and (C) an anionic polyurethane emulsion, having a glass transition temperature of -20 ° C or lower An aqueous adhesive composition characterized by the above.   (A) 1 to 20 parts by weight of an alkylene glycol benzoate ester and 100 parts by weight of (C) a copolymer emulsion of vinyl acetate and another ethylenically unsaturated monomer (solid content) The aqueous adhesive composition according to claim 2, comprising 2 to 50 parts by mass (solid content) of an anionic polyurethane emulsion. The aqueous adhesive according to any one of claims 1 to 3, comprising one or more selected from organic polyisocyanates, polyamide polyamine epichlorohydrin resins, and oxazoline group-containing polymers. Composition.