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
1993-10-18
1995-04-25
Michl, Paul R.
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...
524408, 524410, 524412, 524167, 524169, 524171, C08J 510, C08K 310, C08L 2312
Patent
active
054099803
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to synthetic resins which are made flame and smoke retardant by the addition of certain flame and smoke retardant materials, while retaining their mechanical and/or optical properties.
BACKGROUND OF THE INVENTION
Flame and smoke retardant materials generally fall into two categories, halogenated retardants and non-halogenated retardants. Retardants, as used unmodified herein, refers to both flame and smoke retardants. Non-halogenated systems, such as magnesium hydroxide, aluminum trihydrate, ammonium phosphate, etc. generally require loadings of up to 60% of flame retardant in the resinous compound. This is due to the mechanism by which the retardant works. For instance, aluminum trihydrate operates by releasing water upon heating. The dehydration reaction is endothermic and absorbs some of the heat of reaction of the resinous compound.
In resinous fiber production, loadings above 8% retardant are generally not considered acceptable. This is especially true with respect to fine denier (very small diameter) fibers. Lower loadings may be achieved by the use of halogenated systems. See, for example, U.S. Pat. No. 4,006,118 showing a brominated alkoxydiphenyl sulfone derivative useful as an additive in thermoplastic polymer compositions, to act as a flame retardant.
However, even most halogenated retardant compounds cannot achieve acceptable flame and smoke retardancy with such small load levels. Thus, manufacturers have turned to the use of hybrid retardants comprising both non-halogenated and halogenated systems. The two systems seem to have a synergistic effect and can be used together at lower load levels to achieve better flame and smoke retardancy than either compound alone could achieve.
Antimony trioxide (Sb.sub.2 O.sub.3) is one non-halogenated compound which has been used as a flame retardant additive in conjunction with halogenated retardant compounds. Antimony trioxide is a particulate compound and is mixed with the base compound and the halogenated retardant compound to form a flame retardant system.
Heretofore however, the addition of particulate retardants such as antimony trioxide has caused a deterioration in the physical properties of the resin, specifically, a reduction in strength and a deterioration in the optical properties of the material. Thus when halogenated retardant compounds are used alone, they generally do not perform satisfactorily in producing a flame retardant material. When inorganic particulates are added, the physical properties of the material, particularly mechanical strength and optical properties, are greatly diminished.
SUMMARY OF THE INVENTION
The present invention overcomes these deficiencies by providing a flame retardant composition including a finely dispersed inorganic ultra fine particulate flame or smoke retardant material where the particles are no larger than 500 nanometers (0.50 .mu.) in size. Preferably, the composition comprises an antimony oxide with brominated alkoxydiphenyl sulfone, and most preferably antimony pentoxide with brominated alkoxydiphenyl sulfone where the particles of antimony pentoxide are below 50 (0.050 .mu.) nanometers in size, and the synthetic resin is a polyolefin, such as polypropylene, polyethylene, ABS, nylon, flexible PVC, PET, polystyrene or a copolymer blend of polypropylene and polyethylene.
DETAILED DESCRIPTION OF THE INVENTION
It has been found that by using particles below 500 nanometers in size (0.50 microns) a resinous product can be produced having substantially the same retardant properties as compositions formulated with larger particle sizes, but without the decrease in strength and optical properties occasioned by the use of larger particles.
The increase in strength may occur due to the increased ability to achieve an even distribution and dispersion of a finer material in the resinous matrix. Furthermore, particles tend to cause cracks and discontinuities in the resinous matrix, especially where the flame retardant material is not evenly dispersed. Thi
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Michl Paul R.
PQ Corporation
Rajguru U. K.
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