JPH0488076A - Pressure-sensitive adhesive composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition having excellent applicability with a flow coater, adhesiveness, etc., and useful for the bonding of an interior trim of automobile by compounding a styrene-butadiene copolymer latex, a tackifier resin and an anionic polyacrylamide resin at specific ratios. CONSTITUTION:The objective composition is produced by compounding (A) 100 pts.wt. (in terms of solid) of a styrene-butadiene copolymer latex (preferably a resin having a glass transition temperature of 0 to -40 deg.C and a toluene- insoluble content of <40wt.%) produced by copolymerizing an acrylic acid ester in the presence of a chain transfer agent (preferably carbon tetrachloride, n-dodecyl mercaptan or t-dodecyl mercaptan) with (B) 1-100 pts.wt., preferably 10-50 pts.wt. (in terms of solid) of a tackifier resin and (C) 0.001-0.05 pts.wt., preferably 0.005-0.02 pts.wt. (in terms of solid) of an anionic polyacrylamide resin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure-sensitive adhesive composition used for adhering automotive interior materials.

For more details, please refer to automotive interior materials, hardboard, plywood,
This invention relates to a pressure-sensitive adhesive used for bonding a rear shelf made of resin felt board and non-woven carpet.

[Conventional technology]

Recently, the mainstream of rear shelf members has been molded bodies having some irregularities.

Conventionally, an air spray gun was used to apply adhesive to such molded objects, but air spray application requires the installation of a special booth due to environmental pollution and adverse effects on the human body. Not only that, but the adhesive becomes atomized and scatters, resulting in low yields and an inevitable increase in costs.

In light of these problems, adhesive application methods using flow coaters have begun to be adopted, but pressure-sensitive adhesives that can be applied uniformly using flow coaters while satisfying the adhesion of nonwoven carpets made mainly of polypropylene, nylon, etc. At present, there is no drug available.

[Problems to be Solved by the Invention] A flow coater is a method in which adhesive is dropped in a curtain shape from a narrow slit and applied to a base material.

Since the base material is passed under a continuous falling adhesive curtain, the equipment is extremely simple and has excellent productivity and environmental issues, but it is highly dependent on the properties of the adhesive.

That is, the formation of the adhesive curtain is an important factor, and the key point is how to prevent the curtain from breaking.

Adhesives for the rear shelf already include acrylic emulsions, synthetic rubber latex, and ethylene-vinyl acetate copolymer emulsions for use with roll coaters, and those for spray application. Emulsions have a proven track record, but when applied with a flow coater, they all cause the curtain to break, making them extremely impractical.

[Means to solve the problem]

With the aim of preventing curtain film breakage during application with a flow coater, the inventors of the present invention, as a result of extensive studies, discovered that anionic polyacrylamide resin was added to adhesive styrene-butadiene latex and Kutsky Fire compound. We found that the combination of the two is extremely effective.
The present invention has now been completed.

That is, the present invention provides: a) 100 parts by weight of the solid content of a styrene-butadiene copolymer latex copolymerized with an acrylic acid ester in the presence of a chain transfer agent; 100 parts by weight C)
0 solid content of anionic polyacrylamide resin
．． 001 to 0.05 parts by weight of the pressure sensitive adhesive composition.

The styrene-butadiene copolymer latex (hereinafter abbreviated as SBR latex) obtained by copolymerizing acrylic ester in the presence of a chain transfer agent used in the present invention has styrene and butadiene as main components, and acrylic ester and A general term for those copolymerized with functional monomers in the presence of a chain transfer agent.

The polymer glass transition temperature of latex is 0 to 40°C.
Preferably, the gel content, that is, the proportion of the Latinx polymer that does not dissolve in toluene, is less than 40% by weight.

Examples of the acrylic ester used in the present invention include ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, lauryl methacrylate, etc. .

Examples of functional monomers used in the present invention include:
Acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, acrylamide, methacrylamide,
Examples include n-methylol acrylamide, hydroxyethyl acrylate, hydroxyethyl methacrylate, glycidyl acrylate, and glycidyl methacrylate.

Examples of the chain transfer agent used in the present invention include carbon tetrachloride, n-dodecylmercaptan, t-dodecylmercaptan, and the like.

Among these, preferred copolymers include styrene and butadiene as main components, and butyl acrylate or 2-ethylhexyl acrylate as the acrylic ester, in terms of stability during emulsion polymerization, adhesive properties, and economic efficiency. I.
, functional group monomers include acrylic acid, itaconic acid,
One or a combination of two or more of acrylamide and hydroxyethyl acrylate as a chain transfer agent,
Copolymerization in the presence of n-dodecyl mercaptan or t-dodecyl mercaptan is preferred.

Furthermore, the copolymerization ratio of these monomers is 20/80 to 80/by weight in terms of the ratio of styrene to butadiene.
20, preferably 40/60 to 60/40.

If the weight ratio of butadiene exceeds 80%, stability during emulsion polymerization, adhesive strength, heat resistance, etc. will be impaired, and if it is less than 20%, problems will arise in adhesiveness.

The copolymerization ratio of acrylic acid ester is 100% of the total monomer
in the range of 1 to 50 parts by weight, preferably 5 to 20 parts by weight.
Parts by weight range.

If the copolymerization ratio of acrylic acid ester is more than 50 parts by weight, adhesive strength and heat resistance will be impaired, and if it is less than 1 part by weight, the internal plasticizing effect will be extremely low and the adhesion to the nonwoven carpet will be impaired. The purpose of the present invention is not satisfied.

The copolymerization ratio of the functional group monomer is in the range of 1 to 20 parts by weight, preferably in the range of 2 to 10 parts by weight, based on 100 parts by weight of the total monomers.

When the copolymerization ratio of the functional group monomer is less than 1 part by weight, the stability during emulsion polymerization is impaired, a stable copolymer latex cannot be obtained, and heat resistance is significantly impaired. If the amount exceeds 20 parts by weight, the stability during emulsion polymerization will be impaired, making it impossible to obtain a stable copolymer latex, and the latex polymer will become hard, resulting in a lack of adhesion to the nonwoven carpet. There are also problems from an economic standpoint.

The proportion of chain transfer agent is 0.00 parts per 100 parts of total monomers.
It ranges from 1 to 5.0 parts by weight, preferably from 1 to 3 parts by weight.

When the proportion of chain transfer agent is less than 0.1 part by weight,
The latex has an extremely low internal plasticizing effect and lacks adhesion to the nonwoven fabric carpet, and if it exceeds 5 parts by weight, the molecular weight of the copolymer will drop significantly, causing problems in adhesive strength and heat resistance.

The tackifying resin used in the present invention includes rosin-based tackifying resins typified by natural or polymerized rosin, modified rosin, glycerin ester of hydrogenated rosin, triethylene glycol ester, and pentaerythritol ester;
Examples include α-pinene, β-pinene, dipentene, terpene phenol, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, alkylphenol resin, coumaron indene resin, xylene resin, and the like.

Among these, water-based desversion type tackifying resins are preferred in view of being blended with SBR latex.

As a water-based desversion type tackifying resin, the solid content is 4.
0-60%, viscosity 100-1000cps, pH 5-
Examples include aqueous desversions of terpene phenol resins, phenolic resins, aliphatic petroleum resins, glycerin esters of rosin, triethylene glycol esters, diethylene glycol esters, pentaerythritol ethers, and the like.

The blending ratio of the tackifier resin is in the range of 1 to 100 parts by weight, preferably 10 to 50 parts, based on 100 parts by weight of the solid content of the SBR latex.

If the blending ratio of the tackifying resin is less than 1 part by weight, adhesion to the nonwoven carpet and pressure sensitivity will be lacking, and if it is more than 100 parts by weight, heat resistance will be impaired and practicality will be lacking.

The anionic polyacrylamide resin used in the present invention is a copolymer of acrylamide with acrylic acid, methacrylic acid, iconic acid, fumaric acid, etc., or a polyacrylamide resin is hydrated by adding sodium hydroxide etc. Molecular weight of resin obtained by decomposition: 1 million to 5
0 million powder or granular resins.

Preferably, one having a molecular weight of about 20 million is easy to handle.

The anionic polyacrylamide resin has a molecular weight of 0.1 to 0.
It is preferable to use it as an aqueous solution with a concentration of 5% by weight.

The blending ratio of this anionic polyacrylamide resin is
Per 100 parts by weight of solid content of SBR latex, 0.
001 to 0.05 parts by weight, preferably 0.005
A range of 0.020 parts by weight is suitable.

The blending ratio of anionic polyacrylamide resin is 0
．． If the amount is less than 0.01 part by weight, no improvement in curtain film breakage prevention is observed, and if it is more than 0.05 part by weight, the drawability is similar to that of starch syrup, resulting in a decrease in workability and a significant increase in solid content. and lack practicality.

This pressure-sensitive adhesive composition may contain antifoaming agents, colorants,
Thickeners, anti-aging agents, leveling agents, vulcanizing agents, etc. may be added to the extent that they do not interfere with curtain film tearing.

As described above, the pressure-sensitive adhesive composition of the present invention is a water-based emulsion type adhesive that has extremely low risks of occupational safety and health, environmental pollution, etc. when adhering rear shelf materials among automobile interior materials. , as well as adhesive strength and heat resistance.
It has extremely high practical value because it has excellent adhesive properties such as moisture resistance and cold resistance, and is also suitable for coating with a flow coater with excellent productivity.

〔Example〕

Next, the present invention will be specifically explained with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

In addition, unless otherwise specified below, parts and percentages are based on weight.

Examples 1 to 8 100 parts of distilled water, 1.0 part of sodium dodecylbenzenesulfonate, and 0.5 part of potassium persulfate were placed in an autoclave equipped with a stirrer, and the autoclave was purged with nitrogen.

Next, a mixed monomer of 50 parts of styrene, 1.10 parts of butyl acrylate, 2 parts of acrylic acid, 2 parts of acrylamide, 1 part of hydroxyethyl acrylate and 2.5 parts of tert-dodecylmercaptan, and 35 parts of butadiene,
Press 1/10 of the total amount of each into an autoclave, and
The temperature was raised to °C and the mixture was reacted for 1 hour.

Subsequently, the remaining mixed monomers and butadiene were continuously fed under pressure over a period of 8 hours, and the remaining monomer treatment was carried out at the same temperature for 7 hours.

After the polymerization reaction was completed, it was cooled to 30°C or less, adjusted to PL+8 with a 20% potassium hydroxide aqueous solution, and the residual monomer was reduced to 1100 pp or less by steam stripping.
00 mesh wire mesh, and the solid content used in the present invention is 50
% SBR latex was obtained.

Using this latex as a base, a tackifier resin and an anionic polyacrylamide resin were blended in the order shown in Table 1 with stirring to obtain a pressure-sensitive adhesive composition of the present invention having a viscosity of 500 to 800 cps.

This adhesive was subjected to the tests shown below, and the results are shown in Table 2.

<Test results> a) Suitability for flow coater Using a single head flow coater (model FL-53F) manufactured by Iwata Yaiki Kogyo ■, coating amount 120 g/]
The adhesive flow rate was adjusted to obtain a coating amount of Tr and 180 g/rrr, and the time until uniform curtain formation was measured. (The shorter the time, the better the flow coater properties.) b) Adhesion test: Apply 150 g/m of adhesive uniformly to the plywood surface using a flow coater, dry for 5 minutes in a 100°C heat dryer, and then immediately A polypropylene nonwoven carpet was cold press bonded and used as a sample. (Press conditions: pressure 1kg/c+
fl, press time 15 seconds) This sample is 25 mm wide and 1 long
Cut to 00mm and test at 180° using Tensilon tensile tester.
Measure the peel strength in the direction.

(Tensile speed 200mm/min) 2-1 Normal adhesive strength The measurement was carried out in a constant temperature room at 23°C and 165%RH.

2-2 Heat-resistant adhesive strength Measurement was carried out at 90 parts at 2°C.

Comparative Example 1 An adhesive composition excluding the anionic polyacrylamide resin from Example 1 was prepared as a prototype, and subjected to the same test as in Example.
The results are shown in Table-2.

Comparative Example 2 An adhesive composition from Example 1 except for the tackifying resin was prepared and subjected to the same tests as in Example 1, and the results are shown in Table 2.

Starcon 213OR Manufactured by Yasuhara Chemical fII, 50% aqueous desversion super ester of terpene phenol resin E-720 Manufactured by Arayo Kagaku Kogyo ■, 50% aqueous desversion Quint 7 of modified rosin resin [IE9503 Manufactured by Nippon Zeon ■, aliphatic hydrocarbon resin 50% aqueous dess version 0.1% anionic polyacrylamide resin manufactured by Mitsui Sasu Anamitsu ■, trade name Acopal R300, molecular weight 2
0 million aqueous solution [Effects of the Invention] The pressure-sensitive adhesive composition of the present invention has excellent productivity and economical suitability for flow coater application in adhesion of automotive interior material adhesives and materials. These materials have extremely high practical value due to their excellent normal adhesive strength and particularly heat resistance, which should be used as adhesives for automobile interior materials.Recently, industrial safety and health, environmental pollution, etc. have become serious concerns for automobile interior materials. For parts manufacturers, this is of great significance.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. a) Based on 100 parts by weight of solid content of styrene-butadiene copolymer latex copolymerized with acrylic acid ester in the presence of a chain transfer agent, b) 1 to 100 parts by weight of adhesion-imparting resin as solid content; c) A pressure-sensitive adhesive composition comprising 0.001 to 0.05 parts by weight of anionic polyacrylamide resin as a solid content. 2. The pressure-sensitive adhesive composition according to claim 1, wherein the chain transfer agent is carbon tetrachloride, n-dodecylmercaptan, or t-dodecylmercaptan. 3. The glass transition temperature of the styrene-butadiene copolymer latex is 0 to -40°C, and the proportion that it does not dissolve in toluene is 4.
The pressure sensitive adhesive composition of claim 1, wherein the pressure sensitive adhesive composition is less than 0% by weight.