Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Patent
1997-05-12
1998-10-13
Sellers, Robert E.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
525109, C08L 6302, C08L 6304
Patent
active
058213058
DESCRIPTION:
BRIEF SUMMARY
The invention pertains to a resin composition comprising epoxy resin, a cross-linking agent (curing agent) for the epoxy resin in the form of a carboxylic anhydride, and at least one allyl network forming compound.
BACKGROUND OF THE INVENTION
Such resin compositions are known from EP 413 386. This document relates to IPNs (Interpenetrating Polymeric Networks) having very favorable properties, in particular for use in the electronics industry. This is the case when the cross-linking agent used for the epoxy resin is a polyhydric phenol. In actual practice, the embodiment using anhydride cross-linking agents proves unsatisfactory. Notably, the Tg obtained is too low, and the electrical properties and the prepreg stability also leave room for improvement.
In addition, it is desired that the use of inexpensive difunctional epoxy resins should give thermal properties which are of the same standard as can be obtained using the multifunctional epoxy resins preferably employed in EP 413 386. Resins based on multifunctional epoxy compounds have been described in WO 85/03515 and WO 86/02085.
Other publications describing allyl-epoxy resin compositions employing anhydrides as cross-linking agent for the epoxy resin are U.S. Pat. No. 2,707,177, DE 35 21 506, GB 994 484, and EP 417 837. This last patent specification teaches the use of ethylenically unsaturated anhydrides, such as maleic anhydride, where the anhydride not only cross-links the epoxy resin but also takes part in the forming of the allyl network.
In JP 04-44287 and in JP 04-015211 a resin composition for flexible printed circuits is described. The resin composition comprises a phtalate based compound with at least two allyl groups per molecule, a copolymer made from ethylene and an .alpha.,.beta.-unsaturated dicarboxylic acid and/or its anhydride, and a copolymer made from ethylene and an ethylenic unsaturated monomer containing an epoxy group. The composition described here is a specific grafted IPN. As the composition described comprises thermoplasts rather than conventional epoxy resins, this composition is not suitable for use in prepregs.
The use of adducts of ethylenically unsaturated anhydrides and aromatic acids as cross-linking agent for epoxy resin is described in BE 627 887. This patent publication also discloses a proposal to use copolymers of maleic anhydride and styrene (SMA) as cross-linking agent for epoxy resin. A drawback to such epoxy resin compositions is that they cannot be used to make so-called prepregs.
Prepregs are widely employed in the manufacture of laminates for the electronics industry, in particular for printed-wire boards. Such manufacture involves impregnating a supporting or reinforcing fabric with a resin, followed by partial curing of said resin. Such impregnated fabric is commonly referred to as prepreg. Manufacturing a printed-wire board involves laminating one or more layers of prepreg with, say, one or more layers of copper.
Processing prepregs into boards usually involves their being cut down to size and laminated. Both these process steps make stringent demands on the resin with which the fabric is impregnated. For instance, the partially cured resin has to have sufficient sturdiness and a high viscosity, yet it must be sufficiently sticky and liquid to give good adhesion when laminated, and hence good interlaminar strength. The resin may not be too highly reactive, since this will render the required partial curing impossible.
In this connection resin compositions where the epoxy resin is cross-linked with an anhydride-containing copolymer have the drawback of being too brittle to be processed as prepregs. For instance, it proves impossible to cut up such prepregs without a portion of the resin blowing about in the form of a large quantity of dry dust. This is sometimes called a "mushroom effect", after mushroom spores blowing about.
One the one hand, the invention has for its object to enhance the thermal and electrical properties of resin compositions based on allyl compounds and epoxy-resin cross-linked wit
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"Liquid Crystalline Polymers to Mining Applications: Maleic and Fumaric Polymers", Encyclopedia of Polymer Science and Engineering, 9:225-294 (1987).
Buser Antonius Johannes Wilhelmus
Schutyser Jan Andre Jozef
Akzo Nobel nv
Miraglia Loretta A.
Morris Louis A.
Sellers Robert E.
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