JP2008127450A - One-pack type adhesive composition for precoat - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a one-pack type adhesive composition for precoat, useful as an adhesive for precoat of a skin material, for example, in the production of interior equipment of an automobile, and having a shelf life over a long period. <P>SOLUTION: The one-pack type adhesive composition for the precoat is obtained by dispersing a mixture of two or more kinds of thermoplastic polymers containing a carboxylic acid group or an anhydride group thereof, and having softening points ≥30°C different from each other, a thermoplastic elastomer and an adhesiveness-imparting agent in an organic solvent, and is free from a latent curing agent. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an adhesive composition for a one-part precoat, more specifically, an organic solvent obtained by adding a thermoplastic elastomer and a tackifier to a mixture of at least two kinds of specific thermoplastic polymers having different softening points above a specific temperature. It is useful as an adhesive for pre-coating the skin material, for example, in automobile interior parts made by bonding and laminating a suitable base material layer and skin material, especially after being applied to the skin material and dried. The present invention relates to an adhesive composition for the purpose of extending the shelf life until bonding to a base material layer over a long period of, for example, 6 months to 2 years.

For automobile interior parts, for the purpose of upgrading, various base material layers are bonded and laminated with various skin materials. Recently, olefin-based materials are used for both base material layers and skin materials for environmental measures. It's getting on.
By the way, as an adhesive for pre-coating the above-mentioned skin material, thermoplastic polymers containing carboxylic acid groups or anhydride groups thereof [especially olefin polymers such as polypropylene and styrene-ethylene-butene-styrene copolymer (SEBS)] and latent curing. As an agent, there has been proposed a one-pack type precoat adhesive in which a polyamine compound (for example, a hydrazide-based polyamine) is dispersed in an organic solvent (see, for example, Patent Documents 1 and 2).

JP 2000-198940 A (pages 1 to 3) JP 2003-094524 A1 (page 1-2)

  However, these adhesives gradually crosslink even at room temperature due to the latent curing agent of the compounding components. Therefore, the adhesive is applied to the skin material especially for pre-coating and dried, and then applied to the base material layer. The shelf life until the bonding was short, and for example, surface hardening occurred in 3 to 4 months, and it was often impossible to use for bonding.

  The inventors of the present invention have made extensive studies to solve the problem of shelf life. In the proposed adhesive, the latent curing agent is omitted, and instead, the carboxylic acid group or its anhydride group is used. If a thermoplastic polymer containing at least two mixtures having different softening points above a specific temperature and a thermoplastic elastomer and a tackifier are added to the mixture, the inherent strength required of the adhesive and appropriate heat resistance It was found that the intended shelf life can be extended over a long period of 6 months to 2 years, and the present invention has been completed.

  That is, the present invention comprises a mixture of at least two thermoplastic polymers containing a carboxylic acid group or an anhydride group thereof and having a softening point of 30 ° C. or higher; a thermoplastic elastomer and a tackifier are dispersed in an organic solvent. In addition, the present invention provides an adhesive composition for a one-component precoat, which does not contain a latent curing agent.

  According to the one-pack type precoat adhesive composition of the present invention, it is useful for the precoat of a skin material in the production of automobile interior parts, and has a shelf life of 6 months to 2 years, and is appropriately heated. By the treatment, the amount of residual solvent can be further reduced, which is more advantageous in terms of safety and health at the manufacturing site.

As the thermoplastic polymer containing a carboxylic acid group or an anhydride group thereof (hereinafter referred to as a COOH-modified polymer) in the present invention, an olefin polymer, a butadiene polymer or an ester polymer each containing a carboxylic acid group or an anhydride group thereof. Polymers, carbonate polymers, urethane polymers, amide polymers, etc. are exemplified, but as typical examples of particularly preferred olefin polymers, unsaturated dibasic acids (eg, maleic acid, fumaric acid, citraconic acid, mesaconic acid, etc.) Alternatively, polypropylene (COOH-modified PP) modified by introducing an anhydride thereof, propylene-1-butene-ethylene copolymer (COOH-modified PBE), propylene-1-butene copolymer (COOH-modified PB), styrene-ethylene-butene-styrene Copolymer (COOH-modified SEBS), ethylene - vinyl acetate copolymer (COOH-modified EVA), ethylene - acrylate copolymers (COOH-modified EEA) and the like. Among these COOH-modified polymers, at least two kinds of mixtures having different softening points of 30 ° C. or more are appropriately selected and used. When the difference between the softening points is less than 30 ° C., the temperature range at the time of bonding the adherends that can be bonded becomes narrow.
In the COOH-modified polymer mixture, for example, two thermoplastic polymers (especially olefin polymers) having different softening points of 30 ° C. or more are mixed in a weight ratio of 1/9 to 9/1, preferably 7/3 to 3/7. The one mixed with is optimal.

  Examples of the thermoplastic elastomer used in the present invention include styrene butadiene copolymers such as styrene-butadiene copolymer, styrene-acrylonitrile-butadiene copolymer, styrene-butadiene-butylene-styrene copolymer, styrene-ethylene-butylene-styrene copolymer, Styrene-butadiene-styrene copolymer or acid-modified product thereof and / or hydrogenated product thereof; amorphous polyalphaolefin; ethylene vinyl acetate copolymer; other styrene copolymers such as styrene-isoprene copolymer, styrene-isoprene- Styrene copolymer, styrene-ethylene-propylene-styrene copolymer, styrene-ethylene-butene-styrene copolymer, styrene-ethylene-ethylene-propylene-styrene Polymer, and the like. The amount used is usually 5 to 100 parts, preferably 10 to 50 parts per 100 parts of the COOH-modified polymer mixture (parts by weight, hereinafter the same). If it is less than 5 parts, the temperature range at the time of bonding of adherends that can be bonded becomes narrow, and if it exceeds 100 parts, the adhesive force to the base material layer tends to decrease.

  Examples of the tackifier used in the present invention include rosin resin, rosin acid ester, petroleum resin, coumarone indene resin, phenol resin, terpene phenol resin, xylene resin, and their hydrogenation, unbalance, and partial hydrogenation modification. Examples include the body. The amount used is usually 50 to 150 parts, preferably 50 to 100 parts, per 100 parts of the COOH-modified polymer mixture. If it is less than 50 parts, the temperature range at the time of bonding of adherends that can be bonded becomes narrow, and if it exceeds 150 parts, the adhesive force to the base material layer tends to decrease.

  The adhesive composition for a one-pack type precoat according to the present invention comprises a predetermined organic solvent (toluene, xylene, benzene, 1,1,1-trichloro) in a predetermined proportion of the COOH-modified polymer mixture, the thermoplastic elastomer and the tackifier. Ethane, methylene chloride, cyclohexane, alkylcyclohexane, etc.) and, if necessary, ordinary thermoplastic resin (acrylic resin, vinyl resin, polyamide resin, polyester resin, polyolefin, polyurethane, SEBS, etc.) An appropriate amount of an olefin-based adhesion agent, dyeing pigment or the like may be added.

The precoat skin material according to the present invention is applied to various skin materials (for example, polyolefin foams such as polyvinyl chloride foam, polyethylene, polypropylene, etc.) at a thickness of 5 to 500 μm, and 80 to 120 ° C. X It can be produced by drying with heating for 30 to 300 seconds. The obtained precoat skin material has a shelf life of as long as 6 months to 2 years, and maintains good adhesion to an olefin material having low polarity and difficult to bond.
In addition, this precoat skin material is heated at 165 to 200 ° C. for 30 to 300 seconds to further volatilize the solvent contained in the adhesive layer, so that it is more safe in terms of safety and hygiene at the production site of automobile interior parts described below. It will be advantageous.

The method for manufacturing an automobile interior part according to the present invention can be carried out by a vacuum forming method under heating according to the following procedure using the above-mentioned precoat skin material.
First, while maintaining various substrate layers (for example, ABS plate, Noryl plate, ASG plate, polycarbonate plate, PP board, wood-based composite board, steel plate) at a surface temperature of 25 ° C or higher, preferably 45 to 90 ° C, This is overlaid with a pre-coated skin material heated at 165 to 200 ° C. for 30 to 300 seconds, and subjected to thermocompression bonding for 10 seconds or more under a pressure of 0.1 kg / cm ² or more to perform molding and adhesion simultaneously.
Thus, for example, inside trims such as door rims, front pillars, rear pillars, deck side trims, and center pillars; instrument panels; molded ceilings; automobile interior parts (automobile interior panels) such as console boxes are obtained.

Next, an Example and a comparative example are given and this invention is demonstrated more concretely.
Examples 1-8 and Comparative Examples 1-5
(1) Preparation of adhesive The number of parts of COOH-modified polymer, thermoplastic elastomer and tackifier shown in Table 1 below are added to an organic solvent and stirred and dispersed at 60 ° C. for 2 hours to obtain an adhesive.

(2) Manufacture of automobile interior panel and evaluation of adhesion i) The adhesive of (1) above was applied to a 2 mm thick polypropylene foam skin material at a dry film thickness of 40 μm, dried at 60 ° C. for 5 minutes, and precoated Get the skin material.
ii) Next, such a pre-coated skin material is heated at 195 ° C. for 2 minutes and kept at a surface temperature of 140 ° C. or 100 ° C., and is laminated on a PP substrate heated at 110 ° C. for 45 seconds and having a surface temperature of 55 ° C. or 35 ° C. In addition, it is clamped under the condition of 0.075 MPa × 20 seconds to obtain an automobile interior panel.

Note 1) Hydrogenated styrene-butadiene copolymer Note 2) Styrene-isoprene copolymer Note 3) Partially hydrogenated styrene-butadiene-butylene-styrene copolymer Note 4) Aromatic petroleum produced by Shin Nippon Petrochemical Resin, “Nisseki Neopolymer 170S”
Note 5) Aromatic petroleum resin "Nisseki Neopolymer 120" manufactured by the same company.
Note 6) “DDH” manufactured by Otsuka Chemical Co., Ltd.

iii) About this automobile interior panel, peel strength and heat-resistant creep were measured under the following conditions, and the results are shown in Table 2. In addition, in the automotive interior panel, the precoat skin material used for the production thereof was used immediately after production (initial stage) and after being left at 40 ° C. for 60 days after production.
Peel strength : Measured after bonding at 20 ° C. and 65% RH × 24 hours (N / 25 mm); FMB indicates material failure of the skin material, and BAF indicates interface failure from the substrate side.
Heat resistant creep : After 20 ° C. × 24 hours, a load of 100 g / 25 mm in a 90 ° C. atmosphere is applied in the 90 ° angle direction, and the peel length (mm) after 24 hours is measured.

Claims (8)

  A mixture of at least two thermoplastic polymers containing a carboxylic acid group or its anhydride group and having a softening point different by 30 ° C. or more; comprising a thermoplastic elastomer and a tackifier dispersed in an organic solvent, and a latent curing agent A one-component precoat adhesive composition characterized by not containing any of the above.   The adhesive composition for a one-pack type precoat according to claim 1, which is 5 to 100 parts by weight of a thermoplastic elastomer and 50 to 150 parts by weight of a tackifier with respect to 100 parts by weight of the thermoplastic polymer mixture.   The thermoplastic polymer mixture is a mixture of two thermoplastic polymers containing a carboxylic acid group or an anhydride group thereof and having a softening point of 30 ° C or more different in a weight ratio of 1/9 to 9/1. The adhesive composition for a one-pack type precoat as described in 1 or 2.   The one-pack type precoat adhesive composition according to any one of claims 1 to 3, wherein the thermoplastic elastomer is a styrene / butadiene copolymer and / or a hydrogenated product thereof.   The manufacturing method of the precoat skin material characterized by apply | coating and drying the adhesive composition for a one-component type precoat as described in any one of Claims 1 thru | or 4 to the skin material of the polyolefin foam in an automotive interior part .   The precoat skin material obtained by the manufacturing method of Claim 5.   A method for producing an automobile interior part, comprising bonding the precoat skin material according to claim 6 to a polyolefin base layer in an automobile interior part by a vacuum forming method under heating.   An automobile interior part obtained by the manufacturing method according to claim 7.