Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1997-07-25
1998-09-22
Morgan, Kriellion S.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
525507, 528 87, 528103, 528104, 528108, 528398, C08G 6508, C08G 6514, C08G 5940
Patent
active
058114866
DESCRIPTION:
BRIEF SUMMARY
The present invention relates generally to flame-retardant materials for covering and enveloping electrical and electronic components. More specifically, the present invention relates to flame-retardant reaction resin molding materials that are useful for serving as casings and coverings for electrical and electronic components.
Flame-retardant reaction resin molding materials that are reliable to process are required for covering and enveloping electrical and electronic components. Particularly given passive components, reaction resins that can be processed by casting are thereby standard. Epoxy resins that can be highly thermally stressed and thereby exhibit good mechanical and electrical properties are employed therefor to a great extent. The low-molecular or, respectively, oligomeric initial constituents can be converted to high-quality duroplastic materials upon employment of a great range of hardening agents such as, for example, carboxylic acid anhydrides, amines, phenols or isocyanate or, respectively, by ionic polymerization. The low-molecular through oligomeric initial condition of the epoxy resins is responsible for the advantageous processing behavior of epoxy resins. They can be highly filled with inorganic, inert fillers and can still be processed as casting resin even then.
The flame-retardant finishing of epoxy resin molding materials is currently generally accomplished with halogen-containing and specific bromine-containing aromatic constituents. These embedded constituents, which frequently contain antimony trioxide as a synergist, however, present additional problems in the case of a fire. Given carbonization or combustion, they release decomposition products that are corrosive and, under unbeneficial conditions, ecologically and toxicologically suspect. A substantial technical outlay, moreover, must also be exerted for risk-free waste disposal by incineration.
Phosphorous-containing additives for epoxy resins that improve the flame-retardancy have been recently disclosed. U.S. Pat. No. 5,262,456 proposes that a phosphinic acid or, respectively, phosphonic acid derivative be bonded with alcoholic hydroxyl groups in an epoxy resin molding material. DE 42 37 132 discloses employing phosphorous constituents on a phosphine oxide or, respectively, phosphonate basis as a reaction resin constituent for increasing flame-retardancy. DE 43 08 185 A1 discloses that polyepoxy compounds be converted into phosphorous-containing epoxy compounds by conversion with a phosphonic acid anhydride and that these epoxy compounds then be crosslinked with known hardener constituents into flame-retardant molding materials.
A shared disadvantage of these phosphorous compounds, however, is their relatively low phosphorous content. As a consequence thereof, substantial quantities of these phosphorous-containing compounds are required in order to obtain a satisfactory flame-retardancy. Clear limitations in the workability of such modified reaction resin systems thereby derive because of the high viscosity of these phosphorous constituents particularly observed given phosphorous-modified epoxy resins. The phosphonic acid derivatives are in fact usually lower in viscosity and can thus be advantageously utilized for casting technology. However, the exhibit a weaker flame-retardant effect and must therefore be utilized in higher concentration, which can in turn negatively influence the molding material properties.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to modify a reaction resin system on an epoxy resin basis such that a molding material manufactured therefrom meets the flame-retardant specifications demanded for electronic components, without negatively affecting the workability of the reaction resin system, the molding material properties or the dependability of a component covered or enveloped with the molding material, and such that the molding material does not produce and eco-toxicologically harmful decomposition products when burned.
The invention is based on the discovery o
REFERENCES:
patent: 3373231 (1968-03-01), Cherbuliez et al.
patent: 5262456 (1993-11-01), Wipfelder et al.
patent: 5587243 (1996-12-01), Von Gentzow et al.
patent: 5624979 (1997-04-01), Kleiner et al.
Plundrich Windfried
Wipfelder Ernst
Morgan Kriellion S.
Siemens Aktiengesellschaft
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