Flame-retardant resin composition

Compositions: coating or plastic – Coating or plastic compositions – Contains fireproofing or biocidal agent

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Details

428921, 524140, 524141, 524143, 252601, 252609, C09K 2112, C08K 552

Patent

active

058715703

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a halogen-free and flame retardant resin composition excellent in physical properties such as impact strength, heat resistance and moldability, which is also excellent in chemical resistance and heat-induced discoloration resistance, and improved in silver streaks.


BACKGROUND ART

Of molded articles, electric and electronic parts used in an OA (Office Automation machines)-field for some specific uses are required to be of resin compositions excelled in physical properties such as flame retardancy, impact strength and heat resistance. For example, required are those not less than 40 kg-cm/cm in notched Izod impact strength and heat resistance of not less than 100.degree. C. in HDT (heat distortion temperature). Besides those properties, chemical resistance and moldability are further required. As such resin compositions, polycarbonate-type resins or ABS resins are being used widely.
In recent years, especially with resins used as materials of electric or electronic parts, are required to be safe to fire, hence the material resins are often required to have a high degree of flame retardancy to pass UL-94 (U.S. Underwriters Laboratory Standard) V-0 and, therefore, various flame retardants have been developed and studied.
For the impartation of such a high degree of flame retardancy to a resin composition, generally used is a halogen-type compound as a flame retardant, if necessary, in combination with a flame retardant auxiliary such as antimony trioxide. Halogen-type compounds with their high flame retardant effect, however, have such defects as free halogen gases or halogen compounds resulting from the decomposition of the halogen-type compounds during resin processing is likely to cause corrosion of an extruder cylinder or die surface or corrosion of metal portions of electric or electronic parts, which possibly causes contact failure or poor conduction. The gases resulting from the decomposition of the halogen-type compounds include poisonous ones in extremely minute amounts, Hence, strongly desired is development of a flame retardant resin composition not containing even traces of halogen-type compounds.
As one of such flame retardants, a kind of phosphorus-type compounds is being studied in good earnest with regard to their application possibilities. Generally, however, the flame-retarding effect of the phosphorus-type compounds is lower than that of halogen-type ones, hence addition of a greater amount thereof is required if a high degree of flame retardancy is needed. And this results in lowering of physical properties such as impact strength and heat resistance and it comes to be extremely difficult to keep them sufficiently high together with flame retardancy.
Various studies have been made to date for solving such problems and resin compositions comprising polycarbonate resins, polyalkylene terephthalate resins, graft copolymers, phosphorus-type compounds and fluorocarbon-type resins with or without limitations of their blending ratios are disclosed in, for example, Japanese Laid-open Patent Publication No. 6-192553 and Japanese Patent Publication No. 6-242055.
The resin compositions mixed with such phosphorus-type flame retardants, unlike those mixed with halogen-type flame retardants, have particular phenomena caused by the decomposition of the phosphorus-type flame retardant during resin processing such as yellowing of molded articles and easy formation of silver streaks in the surface thereof. As to yellowing, in particular, there is a further problem, among others, of increased yellowing of the molded articles when they are used under high-temperature conditions.
Of the required physical properties, especially important is the chemical resistance, which is often required to be much higher with spread of uses for such electric parts in recent years.
An extensive series of studies have been made for solving of such problems and with regard to the improvement of resistance to heat-induced discoloration, flame retardant resin compositions admixed

REFERENCES:
patent: 4927870 (1990-05-01), Ogoe et al.

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