Stock material or miscellaneous articles – Composite – Of epoxy ether
Patent
1997-03-10
1998-06-02
Krass, Frederick
Stock material or miscellaneous articles
Composite
Of epoxy ether
428415, 428417, 428901, 523429, 523466, 528 27, 528103, 528108, 528367, 528368, 528398, 528399, 525502, 525504, 525505, 525507, 525525, C08G 5914
Patent
active
057596905
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to epoxy resin mixtures for the production of prepregs and composites, as well as prepregs and composites produced from these epoxy resin mixtures.
Composites based on epoxy resins and inorganic or organic reinforcement materials have achieved great significance in many areas of technology and daily life. The reasons for this are, on the one hand, the relatively simple and safe processing of the epoxy resins, and, on the other hand, the good mechanical and chemical property profile of the hardened epoxy resin molded materials, which allows adaptation to various purposes of use and advantageous utilization of the properties of all the materials which are part of the composite.
It is advantageous for processing of epoxy resins to produce composites to take place via the production of prepregs. For this purpose, inorganic or organic reinforcement materials or Embedding components in the form of fibers, non-woven and woven materials, or of flat shaped articles, are impregnated with the resin. In most cases, this is done with a solution of the resin in a solvent which can evaporate easily or is easily volatile. The prepregs obtained as a result are not allowed to be tacky after this process, but also not hardened yet, rather the resin matrix should only be in its prepolymerized state. In addition, the prepregs must have a sufficiently long shelf life. For example, for the production of circuit boards, a shelf life of at least three months is required. During further processing to form composites, the prepregs must also melt on when the temperature is increased, and form as strong and permanent a bond as possible with the reinforcement materials or embedding components, as well as with the materials provided for the composite, under pressure, i.e. the cross-linked epoxy resin matrix must form a high level of interfacial adhesion to the reinforcement materials or embedding components, as well as to the materials to be bonded, such as metallic, ceramic, mineral, and organic materials.
In the hardened state, the composites are generally required to have high mechanical strength and thermal stability, as well as chemical resistance and heat distortion, or resistance to aging. For electrotechnical and electronic applications, the demand for permanent, high electrical insulation properties is added, and for special purposes of use, a plurality of additional requirements is added. For use as a circuit board material, for example, the requirements are great dimensional stability over a wide temperature range, good adhesion to glass and copper, high surface resistivity, low dielectric loss factor, good processing behavior (ability to be punched, drilled), low water absorption, and high corrosion resistance.
A requirement which has gained increasing importance recently is the demand for flame resistance. In many areas, this requirement has top priority, because of danger to people and property, for example in the case of construction materials for aircraft and automobile construction and for vehicles in public transport. For electrotechnical and especially electronic applications, flame resistance of circuit board materials is absolutely necessary, because of the high value of the electronic components mounted on them.
To assess the flammability, one of the toughest material tests, namely the V-0 classification according to UL 94 V, has to be passed. In this test, a test element has a defined flame applied to its lower edge, while it is vertical. The total of the burning times of ten tests is not allowed to exceed 50 s. This requirement is difficult to fulfill, particularly if the material is thin, as is the case in electronics. The epoxy resin which is in technical use worldwide for FR4 laminates only meets this requirement because it contains approximately 30 to 40% ring-brominated aromatic epoxy components, with reference to the resin, i.e. approximately 17 to 21% bromine. For other purposes of use, comparably high concentrations of halogen compounds are used, and they
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Huber Jurgen
Kapitza Heinrich
Rogler Wolfgang
von Gentzkow Wolfgang
Krass Frederick
Siemens Aktiengesellschaft
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