Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Utility Patent
1998-02-20
2001-01-02
Sellers, Robert E. L. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C523S457000, C523S458000, C523S459000, C523S466000, C523S468000, C525S107000, C525S111000, C525S423000, C525S438000, C525S463000, C525S480000, C525S523000, C528S110000
Utility Patent
active
06169159
ABSTRACT:
This invention relates to halogenated epoxy resin flame retardants and flame resistant thermoplastic resin compositions containing such flame retardants. The flame resistant thermoplastic resin composition using said flame retardant not only has a high degree of flame retardation, but it also affords excellent processability in that it has properties such as excellent heat resistance, resistance to hydrolysis, flow, moldability, mechanical characteristics, and so on, and in that it will not gel in an injection molder or extruder, showing excellent processability. In addition, this flame resistant resin composition can be used in OA (office automation) machine parts and home appliances, connectors, housings, automotive parts, transformers, coil bobbins, and like areas requiring flame resistance, durability, and resistance to hydrolysis.
BACKGROUND OF THE TECHNOLOGY
Thermoplastic engineering plastics containing carbonyl groups in the main chain, such as polyester resins including polyethylene terephthalate (abbreviated as PET), polybutylene terephthalate (abbreviated as PBT) polyamide resins such as nylon and the like, polycarbonate resins and the like, exhibit good mechanical properties and excellent electrical insulation and moldability. Polymer alloys of any combination containing at least one component selected from the above thermoplastic resins with other thermoplastic resins such as ABS or like polystyrene resins, polyolefin resins such as polyethylene (abbreviated as PE), polypropylene (abbreviated as PP), and polyether resins such as polyacetal, exhibit features embodying excellent properties in flow, heat resistance, dimensional stability and the like. Resins and polymer alloys having carbonyl groups in these main chains have been much used recently in parts of OA machines and home appliances, housings, connectors, automotive parts, and the like.
However, resins containing carbonyl groups in the main chain and polymer alloys thereof, are flammable and hydrolyzable. This prompted efforts at improving their flame retardation and resistance to hydrolysis . In particular, the fields of electrical and electronic parts such as in OA machines, home appliances and so on and automotive parts require not only flame resistance, but also retention of electrical insulation and mechanical strength under high temperature and high humidity environments, where improved resistance to hydrolysis is also considered to be important.
A variety of halogenated organic compounds have been proposed to impart flame resistance to thermoplastic resins containing carbonyl linkages in the main chain in the past. Typical ones include tetrabromobisphenol A (abbreviated as TBA), decabromodiphenyl ether (abbreviated as DBDPE), brominated polycarbonate, brominated polystyrene, brominated epoxy resin, brominated epoxy resins with their epoxy groups completely blocked with tribromophenol (abbreviated as TBP), and the like. In particular, the first two inexpensive compounds are often used.
However, TBA or DBDPE used as a flame retardant is deficient in that it tends to bleed out, substantially reducing the surface characteristics of the molded articles. That is, the surface of the molded article is fogged, becomes chalky, or loses luster. An epoxy resin which is nearly completely blocked with TBP has essentially no epoxy groups left so that one cannot expect to make any improvement in resistance to hydrolysis. When a brominated epoxy resin is blended with polyesters such as PET, PBT, and the like, polycarbonate, polyamide resin, and so on, it is exposed to high temperatures over a long period of time in an extruder or molding machine during mixing, presenting the risk that the two terminal epoxy groups may react with the terminal carboxyl or hydroxyl groups of the polyester or the terminal phenolic hydroxyl groups of the polycarbonate or the active hydrogen of polyamide and so on, causing discoloration or gellation. Japanese Patent Application laid-open H8-157592 proposes a halogenated resin containing no terminal epoxy groups, but the lack of an epoxy group fails to provide any anticipated effect of inhibiting hydrolysis for polyester, polycarbonate, or polyamide resins all having carbonyl linkages in the main chain.
SUMMARY OF THE INVENTION
The present invention provides an improved flame retardant and a flame resistant thermoplastic resin composition by the combined use of a halogenated bisphenol epoxy resin with part of the epoxy groups being blocked by a C
1-8
alcohol, an auxiliary flame retardant, an inorganic filler, and optionally other additives, thereby imparting a high degree of flame resistance as well as excellent resistance to hydrolysis, heat resistance, and flow, without causing gellation in the cylinder or mold of an injection molder or extruder.
DETAILED DISCLOSURE OF THE PREFERRED EMBODIMENTS
This invention is a halogenated epoxy resin type flame retardant for a thermoplastic resin having carbonyl linkages in the main chain, mainly comprising a halogenated epoxy resin type flame retardant represented by general chemical formula 1,
Formula 1:
where X is Formula I:
or Formula II:
and the ratio, (Formula I)(Formula II), is 2/1-1/2, having an epoxy equivalent in the range of 750-4000 g/eq, and having the degree of polymerization n in the range of 0-10; and a flame resistant thermoplastic resin composition comprising, per 100 parts by weight of a thermoplastic resin containing carbonyl linkages in the main chain, 1-40 parts by weight of said halogenated epoxy resin flame retardant, not more than 10 parts by weight of a auxiliary flame retardant, and not more than 150 parts by weight of an inorganic filler.
The halogen-containing flame retardants of this invention are explained below. The halogenated epoxy resin flame retardants used in this invention are compounds having a structure in which part of the epoxy groups of the halogenated bisphenol epoxy resin are blocked by a C
1-8
alcohol. That is, this is a halogenated epoxy resin flame retardant shown by General Formula 1 in which the epoxy equivalent therein is in the range of 750-4000 g/eq, preferably 800-3500 g/eq, more preferably in the range of 1000-3000 g/eq. An epoxy equivalent of 750 g/eq or less means a high epoxy group concentration, thus a low molecular weight, so that it offers little heat resistance and tends to gel when blended with a thermoplastic resin. Its low molecular weight is disadvantageous in that it has low softening point and is difficult to handle. An epoxy equivalent exceeding 4000 g/eq means a low epoxy content so that it is not expected to give much effect of inhibiting the hydrolysis of a thermoplastic resin containing carbonyl linkages in the main chain.
The degree of polymerization, n, in Formula 1 should be in the range of 0-10, preferably 0.5-9, most preferably 1-8. A degree of polymerization exceeding 10 means a low epoxy concentration and cannot be expected to provide an effect of inhibiting hydrolysis. It will also have a high melt viscosity, making it difficult to achieve a high flow rate.
The ratio of (Formula I)/(Formula II) in the general formula 1 is 2/1-1/2, preferably in the range of 1.8/1-1/1.8 and 1.5/1-1/1.5. A ratio exceeding 2/1 means a higher epoxy group concentration so that its heat resistance will fall when it is blended with a thermoplastic resin, tending to cause gellation. A ratio less than 1/2 means a low epoxy group content, which cannot be expected to enhance resistance to hydrolysis effectively.
The alcohol used for blocking the epoxy groups of the halogenated epoxy resin should preferably have not more than 8 carbon atoms, more preferably not more than 6. The use of a compound having 10 or more carbon atoms would mean a considerable reduction in the halogen content in the flame retardant, giving a low flame retardation effect, thereby reducing the heat resistance, heat distortion temperature, and mechanical properties of the resulting flame resistant resin composition. In order to improve flame retardation effect, one may make a combined use of a short chain alcohol and a halog
Kawamoto Toshihiko
Morikawa Yoshiyuki
Sato Tetsunori
Griffin & Szipl, P.C.
Sellers Robert E. L.
Tohto Kasei Co., Ltd.
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