Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Patent
1995-11-22
1997-11-11
Gulakowski, Randy
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
523407, 525 65, 525310, 525360, 525530, 525902, C08F13606, C08F23810, C08L 5100
Patent
active
056865090
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates to a novel adhesion-reinforcing composition for an epoxy resin adhesive, and an epoxy resin structural adhesive composition containing the novel adhesion-reinforcing composition. More particularly, it relates to an ion-crosslinked acrylic resin adhesion-reinforcing composition for imparting toughness and pseudo-curability to an epoxy resin structural adhesive composition, and also relates to an epoxy resin structural adhesive composition containing the acrylic resin adhesion-reinforcing composition, which exhibits an enhanced storage stability over a long storage period and is capable of being widely used for various adherend materials.
The epoxy resin structural adhesive composition of the present invention is valuable as a structural adhesive used for automobiles.
BACKGROUND ART
Epoxy resins have various excellent properties, and therefore, have heretofore been used widely, for example, as an adhesive, an adhesive film, a matrix resin, a casting resin, a powdery molting resin, a paint, an encapsulating agent for electronic circuits, and a base resin for various composite materials.
Nevertheless epoxy resins have a poor impact resistance, and various attempts have been made to improve the impact resistance. Namely proposals of dispersing a polyamide resin or other impact resistance improvers in an epoxy resin have been made. However, the epoxy resin having been incorporated therein the impact resistance improver has a poor pseudo-curability.
In general, it is known that, if a rubber ingredient having a glass transition temperature not higher than -30.degree. C. as an impact resistance improver is incorporated in a plastic material, external stress is absorbed by the incorporated impact resistance improver and thus the impact resistance is greatly enhanced. However, many rubber ingredients have poor practicality for an adhesive for which a high storage stability is required, because, when the rubber ingredients are incorporated in a liquid epoxy resin matrix, the dispersibility greatly varies depending upon the mixing conditions and the resulting compositions have a poor storage stability.
Pseudo-curability also is important for an epoxy resin adhesive. To impart a good pseudo-curability as well as a good impact resistance, it is known that it is effective to incorporate in an epoxy resin a core-shell type modifier composed of an acrylate or methacrylate polymer (Japanese Unexamined Patent Publication No. H2-80483).
By the term "pseudo-curability" used herein we mean a property such that a liquid adhesive or a paste adhesive is solidified into a non-sticky or sticky state when the adhesive is heated to a temperature lower than the thermal hardening temperature. Pseudo-curability is beneficial for an adhesive. Namely, in an automobile industry, when an epoxy resin-based heat-curable adhesive composition is coated on a metal substrate and then the adhesive-coated substrate is subjected to processing such as folding, cutting, degreasing and acid-treatment, the adhesive tends to be partly scattered or separated from the metal substrate or an excessive adhesive is inevitably forced to flow out from the coated area and is difficult to completely remove therefrom. Therefore, the working environment is worsened and a pre-treating liquid used prior to painting is apt be stained with the adhesive. In contrast, if the epoxy resin-based heat-curable adhesive composition coated on a metal substrate is immediately heated in a short time to be thereby pseudo-cured, an excessive adhesive can easily be removed from the coated area on the substrate, and there is no possibility of staining of a pro-treating liquid with the adhesive.
The above-mentioned core-shell type modifier particles composed of an acrylate or methacrylate polymer resin for imparting pseudo-curability and impact resistance exhibit a high compatibility with an epoxy resin which is a matrix of an adhesive composition. Therefore, the modifier particles are apt to exhibit a remarkable viscosity increase during storag
REFERENCES:
patent: 4668736 (1987-05-01), Robins et al.
patent: 4778851 (1988-10-01), Henton et al.
patent: 5177122 (1993-01-01), Shih
Ashida Tadashi
Nagase Toshio
Nakayama Akira
Ohnishi Masahiko
Gulakowski Randy
Nippon Zeon Co. Ltd.
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