Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2001-09-25
2004-08-24
Cheung, William (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C524S406000, C524S407000, C524S440000, C156S272200, C156S275700, C156S345420, C425S175000, C525S100000
Reexamination Certificate
active
06780940
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a resin composition for bonding glass and resin. Specifically, the present invention relates to an adhesive thermoplastic resin composition which can bond glass and reinforced resin in a short period of time without using a heating furnace, and has high adhesive strength at 80° C.
The present invention also relates to a method for rapidly and safely separating adherends bonded together by the above adhesive thermoplastic resin composition without using a heating furnace and without tearing or damaging these adherends so that these adherends can be easily sorted for reuse or recycling.
BACKGROUND OF THE INVENTION
Heretofore, glass and reinforced resins have been bonded together by applying a primer to the glass, drying the glass and then curing and bonding a urethane adhesive. However, this method has the problem of the drying of the solvents and the curing reaction of urethane requiring a long time, as well as the problem associated with using solvents. Hot melt adhesives for bonding glass and resin, which have been developed recently, have low adhesive strength at high temperatures and thus often fail to develop performance as high as required. Japanese Unexamined Patent Publication No. 2000-159938 discloses development of a hot melt adhesive useful for bonding glass and resin. This adhesive necessitates a large heating furnace for heating the large glass plates and formed resin articles used and requires a cycle of heating and cooling operations. This great difficulty prevents practical industrial use of the adhesive.
Japanese Unexamined Patent Publication No. 1998-47580 discloses an IH heater for a hot melt adhesive that includes a material that generates heat when exposed to high frequency induction (heat-generating material) which bonds synthetic resin materials or a synthetic resin material and a metal material using a joint. According to the above invention, the adhesive strength between inorganic reinforced thermoplastic resins and glass is very low. Particularly, the adhesive is not practically usable at 80° C. Therefore, development of an adhesive for glass and inorganic reinforced thermoplastic resins has been desired.
Until now, bonded adherends have been pulverized and dumped. Thus, such parts could not be sorted, reused or recycled. Using a hot melt adhesive to join adherends also has problems because this method requires a large heating furnace since the whole assembly needs to be treated at a high temperature, and adherends thus joined cannot be recycled because they deteriorate when heated. Further, this method requires a cycle of heating and cooling operations, and thus cannot be put into practical use because of this large barrier to industrialization.
In light of the above situation, the recent recycling-oriented society has been strongly demanding a separation method for such adherends which enables reuse of these resources.
An object of the present invention is to provide a thermoplastic resin composition which is a solvent-free heat-resistant hot melt adhesive that bonds in a short period of time without using a heating furnace, and has high adhesive strength between glass and an inorganic reinforced thermoplastic resin at 80° C.
Another object of the present invention is to provide a separation method which does not use a heating furnace and which allows rapid separation and recycling of adherends.
DISCLOSURE OF THE INVENTION
In order to solve the above-mentioned problems, the inventors of the present invention have conducted extensive research and consequently they accomplished the present invention. Specifically, the present invention provides the following adhesive resin compositions and methods for separating the adherends bonded together by these compositions.
1. An adhesive resin composition comprising a heat-generating material (A) which generates heat when subjected to high frequency induction and a thermoplastic resin (B) modified with a monomer having a functional group which reacts with an inorganic substance, the thermoplastic resin (B) having a melting point ranging from 90° C. to 200° C.
2. The adhesive resin composition according to item 1, wherein the thermoplastic resin (B) having a functional group which reacts with an inorganic substance is a polyolefin copolymer modified with a silane compound and/or titanate compound.
3. The adhesive resin composition according to item 1, wherein the heat-generating material (A) is iron and is contained in an amount of at least 10% by weight.
4. A method for separating a bonded article into adherends, the method comprising detaching by induction heating the bonded portions of the adherends bonded together by a thermoplastic resin composition comprising a heat-generating material (A) and a thermoplastic resin (B) modified with a monomer having a functional group which reacts with an inorganic substance and has a melting point ranging from 90° C. to 200° C.
5. The method for separating a bonded article according to item 4, wherein at least one of adherends is glass.
In the present invention, as the heat-generating material (A) which generates heat when subjected to high frequency induction are used carbon steel, alpha iron, gamma iron, delta iron, copper, brass, aluminum, iron-nickel alloy, iron-nickel-chromium alloy, carbon fiber, carbon black and the like. Among these, iron-based substances are favorable in terms of induction heating characteristics, deterioration of resin and relative inexpensiveness. The amount of the heat-generating material used varies depending on its form. The amount is preferably 10 to 90% by weight, more preferably 30 to 80% by weight, particularly preferably 50 to 75% by weight. An amount lower than 10% by weight is not favorable because the heating value is insufficient so that it takes a long time until the adhesive is heated to a temperature which allows adhesion. An amount higher than 90% by weight is unfavorable since adhesive strength is lowered. The heat-generating material may be in any form such as a powder, needles, scales, a mesh, and a nonwoven fabric. The form of the heat-generating material is selected depending on the adhesion process. Heat-generating materials in the form of a powder, needles or plate crystalline or platelike powder are often incorporated into the adhesive resin composition. When the heat-generating material is incorporated, the amount of the heat-generating material is preferably 40 to 80% by weight because of its low heat-generating property. Heat-generating material in the form of a mesh is used in lamination or insert molding. When the heat-generating material is used in lamination, the amount used is preferably 10 to 50% by weight. When the heat-generating material is incorporated, the particle size is preferably 10 to 3000 &mgr;m.
The thermoplastic resins used in the present invention which comprise the component (B) whose melting point ranges from 90 to 200° C. include polyolefin resins, polyamide-based resins, polyester-based resins, among others. The copolymers of these resins are especially preferable in terms of adhesiveness. Considering the need for adhesive strength at a high temperature, the melting point should be at least 90° C., preferably at least 100° C. A melting point higher than 200° C. is unfavorable because the inorganic reinforced thermoplastic resin to be bonded with is partially melted. In view of adhesion processability and adhesive strength at a high temperature, the melting point is particularly preferably 100° C. to 150° C.
In component (B), examples of a functional group which reacts with an inorganic substance introduced into the above resin to increase the adhesiveness to glass include a silane group, silanol group, titanate group, among others. Monomer containing such functional group include a silane compound, titanate compound, among others. Examples include &ggr; aminopropyltriethoxysilane, &bgr; (3,4epoxycyclohexyl) ethyltrimethoxysilane, &ggr; glycidoxypropyltrimethoxysilane, &ggr; methacryloxypropyltrimethoxysilane, N-&bgr; (aminoethyl) &ggr; am
Kosugi Hitoshi
Nakanishi Koji
Ohama Kenji
Sakai Satoshi
Yoshihara Nori
Cheung William
Foley & Lardner
Toyo Boseki Kabushiki Kaisha
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