BONDING AGENT AND RESIN COMPOSITION

Abstract: Improved bonding agent comprises a reaction product or mixture of an epoxyalkylalkoxysilane and a polyamine, and a resin composition comprising as the main ingredient conven­ tional synthetic resin or synthetic rubber and the bonding agent as set forth above, which has excellent adhesion, parti­ cularly durability of adhesion, and is useful as an adhesive or a paint.

Description: This invention relates to a bonding agent and a resin composition containing the bonding agent. More particularly, it relates to a bonding agent comprising a reaction product or mixture of an epoxyalkylalkoxysilane and a polyamine, and a resin composition containing the bonding agent for improving adhesion (particularly durability of adhesion) which is useful as an adhesive or a paint. There have been known and practically used various resin compositions comprising as the main ingredient various synthetic resins or synthetic rubbers, for example, adhesives, sealants, paints, pouring agents, and the like. These resin compositions contain usually a bonding agent in order to improve the adhesion to the substrate to be applied in addition to other conventional additives, such as fillers, platicizers, solvents, dyes and pigments, and flow modifiers. The conventional bonding agents are phenolic resins, petroleum resins, epoxy resins, silane coupling agents, titanate coupling agents and the like. However, these conventional bonding agents are not necessarily satisfactory in the durability of adhesion. It is also proposed to apply a primer to the substrate, but this is not preferable in view of the labor saving. DE-A-2 050 235 describes a size composition for coating glass fibers comprising a silane in an aqueous medium, said silane being a reaction product of an epoxy compound with aminoalkyl compound, for example, a reaction product of a primary or secondary aminoalkyltrialkoxysilane with a monoepoxide, and a reaction product of an epoxyalkyltrialkoxysilane and a primary or secondary amino alkyl compound. DE-A-2 107 360 describes an epoxy-modified diamine-curable urethane resin, which is prepared by reacting a monoepoxide compound with an aromatic diprimary amine to form an adduct of said monoepoxide compound and said aromatic diamine and thereafter mixing said adduct with an isocyanate-containing urethane prepolymer. EP-A-0 054 923 describes a curable resin composition which comprises (A) a hydrolyzable silyl group-containing vinyl resin, (B) a tin compound and (C) a silicon-containing amine (= amino group-containing silane coupling agent), which has improved adhesion to organic substances and is used in coating compositions such as paints for preparing coatings. The present inventors have intensively studied as to improved bonding agent and resin composition containing the bonding agent, and have found that a reaction product or mixture of a specific alkoxysilane compound having an epoxy group and a compound containing two or more amino groups in the molecule exhibits excellent bonding force and hence is useful as a bonding agent and that a resin composition containing the bonding agent show excellent adhesion to the substrate and excellent durability of adhesion. The object of the invention is to provide an improved bonding agent and a resin composition having excellent adhesion, particularly excellent durability of adhesion. According to the present invention, this object is achieved by a bonding agent which is characterized by comprising a reaction product of an approximately stoichiometrically equivalent amount of an epoxyalkylalkoxysilane selected from the group γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane and an aliphatic polyether polyamine having polypropylene glycol nucleus and having a molecular weight of 200 to 3,000. The invention also provides a resin composition which is characterized by comprising 100 parts by weight of a main ingredient selected from synthetic resins and synthetic rubbers and 0.1 to 20 parts by weight of a bonding agent as set forth in claim 1. The above epoxyalkylalkoxysilane and polyamine are mixed in an approximately stoichiometrically equivalent amount or they are reacted in such an amount, by which the desired bonding agent is prepared. The reaction is usually carried out in a suitable solvent, such as aromatic solvents (e.g. toluene, xylene, etc.), esters (ethyl acetate, butyl acetate, etc.), at a temperature of from room temperature to an elevated temperature (e.g. 40 to 60°C) for 20 hours or longer. The bonding agent thus prepared is preferably used as an additive to various resin composition in an amount of 0.1 to 20 parts by weight (as solid), preferably 0.5 to 5 parts by weight, to 100 parts by weight of the resin composition in order to give the resin composition having excellent adhesion, particularly excellent durability of adhesion. The resin composition of this invention comprises mainly a conventional syntheric resin and/or synthetic rubber and the bonding agent as set forth above, optionally other additives such as fillers, plasticizers, solvents, catalysts, antioxidants, and pigments. The synthetic resins used as the main ingredient of the resin composition include conventional polyester resins, epoxy resins, alkyd resins, aminoalkyd resins, and the synthetic rubbers include conventional polyurethane rubber, silicone rubber, modified silicone rubber (i.e. a compound having polyether nucleus and terminal alkoxy group, and a compound having polyether nucleus and terminal isocyanate group, etc.), and polysulfide rubber. Among these, polyester resins and polurethane rubbers are preferable. The resin composition of this invention has excellent adhesion to the substrates (e.g. metallic substances, coated metals, plastics, glass, inorganic materials, wooden products, etc.), particularly excellent durability of adhesion under heating or in water, and hence is useful as an adhesive or a paint. This invention is illustrated by the following Examples. Examples 1 and 2 Preparation of bonding agents: An epoxyalkylakoxysilane (Sila-Ace S-510® or -520®) and a polyamine (Epomic -691®) and toluene are charged into a closed reactor in an amount as shown in Table 1, and the mixture is reacted at 50°C for 24 hours. By checking the disappearance of epoxy group and secondary amino group by IR, the finishing of the reaction is confirmed. The reaction product is used as the bonding agent. The silane compounds and polyamines used above are as follows: Epomic Q-691®: aliphatic polyether polyamine Test of bonding force of the bonding agents: A urethane rubber adhesive (Pandex T-5205®) was diluted with a mixture of toluene and methyl ethyl ketone so as to be in a concentration of 15 % by weight (in solid). To the solution (100 parts by weight) was added the bonding agent (1 part by weight) as prepared in the above Examples 1 and 2. The thus prepared bonding composition was applied to lamination of a Zn steel plate and a polyvinyl chloride (PVC) sheet. The adhesion (dry adhesion strength) of the laminates was tested in a known method [peeling strength after keeping at 20°C, 65 % RH (relative humidity) for 24 hours]. As a result, they showed a dry adhesion strength of 4.4 kg/25 mm. As a reference, a laminate was prepared by using the same urethane rubber adhesive containing no bonding agent, and the dry adhesion strength was measured likewise. As a result, the product showed a dry adhesion strength of 0.3 kg/25 mm. Examples 3 and 4 Preparation of resin compositions: A polyurethane rubber (Pandex T-5205®) or a polyester resin (Dynapol 411®) toluene, methyl ethyl ketone (MEK) and the bonding agent (as prepared in Examples 1 and 2) are mixed with stirring in an amount as shown in Table 2 to prepare the main ingredient. The main ingredient is incorporated with triphenylmethane triisocyanate (Desmodule R® as a crosslinking agent) to prepare an adhesive composition. Test of adhesion of the resin compositions: The adhesion prepared in the above Examples 3 and 4 was applied to one surface of a Zn steel plate with an air spraying device (in weight of 150 g/m²), and it was dried at 80°C for 2 minutes, and thereafter, the coated steel plate was piled on a polyvinyl chloride foam (Olsia MP-877®) and the piled product was heated at 140°C for 5 minutes, pressed with a roller (0.8 kg/cm² x 20 seconds) to prepare a test piece. The test piece was subjected to the test of dry adhesion strength (peeling resistance after keeping at 20°C, 65 % RH (relative humidity) for 24 hours), the test of heat aging resistance (peeling resistance after keeping at 100°C for 7 days), and the test of water resistance (peeling resistance after keeping at 20°C for 7 days). The results are shown in Table 2.

Claims: A bonding agent characterized by comprising a reaction product of an approximately stoichiometrically equivalent amount of an epoxyalkylalkoxysilane selected from the group γ-glycidoxypropyldimethylethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glxycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane and an aliphatic polyether polyamine having polypropylene glycol nucleus and having a molecular weight of 200 to 3,000. A resin composition characterized by comprising 100 parts by weight of a main ingredient selected from synthetic resins and synthetic rubbers and 0.1 to 20 parts by weight of a bonding agent as set forth in claim 1.

Inventors: HIROHIDE, TOMOYASU, MASAAKI, SO, MORI, MASAHITO
Applicants: SUNSTAR GIKEN KABUSHIKI KAISHA
Application year: 1986
Main classification: C08K5
IPC codes: C08K5, C09J201, C09D7