Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Patent
1997-03-10
1998-10-06
Krass, Frederick
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
528 93, 528 94, 528103, 528367, 528368, 528398, 528399, 525502, 525504, 525505, 525507, 525525, 428413, 428415, 428417, 428901, C08G 5930, C08G 5940, C08G 5952, C08G 5954
Patent
active
058177361
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/DE95/01136 Aug. 25, 1995.
BACKGROUND OF THE INVENTION
The invention concerns epoxy resin mixtures for producing prepregs and composites and also the prepregs and composites produced from these epoxy resin mixtures.
Composites based on epoxy resins and organic or inorganic reinforcing materials have become extremely important in many areas of industry and daily life. The reasons include first the relatively simple and reliable processing of epoxy resins and, second, the good level of mechanical and chemical properties of cured epoxy resin molded materials adapt them to different applications and to utilize the properties of all the materials involved in the composite to advantage.
Epoxy resins are preferably processed to composites by way of the production of prepregs. For this purpose, organic or inorganic reinforcing materials or embedding components in the form of fibers, nonwovens and wovens or of flat shaped articles are impregnated with the resin. In most cases this is done with a solution of the resin in an easy-to-evaporate or easy-to-volatilize solvent. The resulting prepregs must not be tacky after this process, but they must not be fully cured either, and instead the resin matrix should merely be in a prepolymerized state. Furthermore, the prepregs must have sufficient stability in storage. For example, at least three months' stability in storage is required for the production of circuit boards. In further processing to yield composites, the prepregs must also melt on at elevated temperatures and they must form a strong and durable bond under pressure with the reinforcing materials and embedding components as well as the materials used for the composite, i.e., the cross-linked epoxy resin matrix must have a high interfacial adhesion with the reinforcing materials and embedding components as well as the materials to be bonded such as metals, ceramics, minerals and organic materials.
When cured, composites are generally required to have a high mechanical strength and thermal stability as well as a good chemical resistance and heat distortion and a high resistance to aging. For electronic and electrotechnical applications, constantly high electric insulation properties are also required, and there are various other additional requirements for special applications. For example, use as a circuit board material requires a high dimensional stability over a wide temperature range, good adhesion to glass and copper, a high surface resistivity, a low dielectric loss factor, good machinability (punchability, drillability), low water absorption and a high corrosion resistance.
Flame resistance is a requirement that has become increasingly important in recent times. In many areas, e.g., for construction materials for aircraft and automotive engineering and for vehicles in public transportation, this requirement has top priority because of the risk to humans and property. Flame resistance of circuit board materials is indispensable for electrotechnical and electronic applications in particular because of the high value of the electronic components mounted on them.
Therefore, one of the strictest material tests, namely the V-0 classification according to UL 94 V, must be passed to evaluate flammability. In this test, a test object is exposed to a defined flame positioned vertically at its lower edge. The total burning time in ten tests must not exceed 50 sec. This requirement is difficult to meet, especially when the material is thin, which is the case in electronics. Epoxy resin, which is used industrially throughout the world for FR4 laminates, meets these requirements only because it contains approx. 30% to 40% ring-brominated aromatic epoxy components, based on the resin, i.e., approx. 17% to 21% bromine. Comparably high concentrations of halogen compounds are used for other applications, often combined with antimony trioxide as a synergist. The problem with these compounds is that although they have excellent flame-retardant properties, they also have some highly objecti
REFERENCES:
patent: 3741858 (1973-06-01), Fujiwara et al.
patent: 4111909 (1978-09-01), Simons
patent: 5376453 (1994-12-01), Gentzkow et al.
patent: 5587243 (1996-12-01), Von Gentzkow et al.
Derwent Abstracts 89-184,043, "Reactive Flame Retardant Composition", Nov. 1987.
"Handbook of Epoxy resins", McGraw Hill Book Company, 1967, pp. 10-12.
"Reactive flame retardant composition-containing compounds obtained by reacting acid phosphate ester with di:glycidyl ether compound useful in thermosetting resins", WPI/Derwent Publications, London, GB, AN 89-184 043.
"Der IR-Lotprozebss aus der Sicht des Basismaterialherstellers", Von H. Schumacher, Galvanotechnik, D-88348 Saulgau, 84 (1993) 11, pp. 3865-3870.
Huber Jurgen
von Gentzkow Wolfgang
Krass Frederick
Siemens Aktiengesellschaft
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