Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1984-11-20
1987-06-09
Schofer, Joseph L.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525119, 525121, C08L 6310
Patent
active
046720928
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
Epoxide resins are widely used as structural adhesives. They produce strong bonds with a wide variety of substrates. However, they are hard materials with low elongation and poor resistance to impact and flexural forces. These mechanical properties, and their high flammability, make them unsuitable for use for certain purposes for which they are otherwise well-suited.
BACKGROUND ART
Various attempts have been made to produce epoxide resin compositions with improved mechanical properties. Examples are described in U.S. Pat. Nos. 3,297,622, 3,316,195, 3,806,483 and 4,128,519. A paper by Trostyanskaya, Babayevskii and Kulik in "Polymer Science U.S.S.R." Vol. 21 pp 1456-1462 describes how epoxidised rubber latices can be incorporated into an epoxide resin using the compatibility provided by the epoxide functional groups and then co-reacting with these functional groups to produce a bonded matrix. Other attempts to improve the mechanical properties of epoxide resins have involved the incorporation of liquid nitrile rubber or the use of particular curing agents. However, the resulting compositions usually have inferior ultimate strength and a lower heat distortion temperature than unmodified resins.
The flammability of epoxide resins has been reduced by incorporating a halogen into the backbone of the resin structure, for example by the use of brominated bisphenol-A in the reaction mixture for producing the resins. Alternatively, conventional fire-retardants such as halogenated compounds, aluminum trihydrate, antimony compounds or phosphorus compounds may be incorporated in the resins. These additives, however, may have undesirable effects on other properties, for example lowering the heat distortion temperature.
DISCLOSURE OF THE INVENTION
According to this invention, a curable epoxide resin composition comprises an epoxide resin adducted with an elastomeric polymer including at least one chlorinated monomer and at least one unsaturated carboxylic acid monomer.
The epoxide resin composition may include more than one epoxide resin and/or more than one elastomeric polymer.
Chlorinated monomers suitable for use in performing the invention are chlorinated butadienes, vinyl chloride and vinylidene chloride. Preferred unsaturated carboxylic acids are acrylic acid and methacrylic acid. The carboxylic acid concentration in the polymer should be between 0.5 and 10 percent and typically is between 1 and 5 percent.
Suitable elastomeric polymers may include more than one chlorinated monomer and/or more than one unsaturated carboxylic acid monomer.
Suitable epoxide resins include bisphenol-A and bisphenol-F types, epoxy-novalak resins and brominated and alicyclic epoxides. The compositions may include more than one such resin.
The invention includes a method of manufacture of such an epoxide resin composition comprising the steps of stirring an aqueous latex of the elastomeric polymer or polymers into the epoxide resin or blend of epoxide resins in liquid state and removing the water.
On removal of the water, adducting reaction takes place between the carboxylic acid groups on the polymer or polymers and epoxide linkages on the epoxide resin or resins, producing the curable epoxide resin composition. The resin or resins must be present in sufficient quantity to ensure that the whole of the polymer or polymers is/are adducts, and is/are preferably present in excess. The product of the adducting reaction is soluble in the resin or resins, so in this case a stable homogeneous solution of the composition in the uncombined excess resin is produced.
MODES OF CARRYING OUT THE INVENTION
If the epoxide resin or blend of resins is sufficiently mobile at temperatures below 100.degree. C., the first step, of stirring the polymer latex into the liquid resin or resin blend at room temperature, will produce a substantially uniform dispersion of polymer latex particles in the liquid resin matrix. Then, in the second step, the mixture is heated above 100.degree. C. to drive off the water. This method may be modifie
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Trostyanskaya et al., "The Effect of Rubber Latex Particles on the Mechanical Properties of Highly Crosslinked Epoxy Polymer" in Polymer Science U.S.S.R., vol. 21, pp. 1456-1462.
Lipman Bernard
Schofer Joseph L.
Scott Bader Company Limited
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