This invention relates to additive compositions that serve as flame retardants and that have the capability, when blended with suitable thermoplastic polymers, of providing thermally-stable flame-retardant thermoplastic polymer compositions. This invention also relates to the resultant flame retarded polymer compositions.
Over the years much effort has been devoted to the discovery and development of effective flame retardants for use in thermoplastic polymers.
Japan Kokai 08-208939 A2, laid open Aug. 13, 1996, describes flame retarded compositions composed of (A) HIPS containing (B) 4-8 parts of tetrabromobisphenol-A and polyhalogenated aliphatic ether derivatives, (C) polyhalogenated diphenylalkanes in an amount of 20-50% of the amount of (B), (D) Sb2O3, and (E) 0.0005-0.05% (as Si) of organic polysiloxane. According to this prior disclosure, the amount by weight of the polyhalogenated diphenylalkanes to be used is at most one-half of the amount of tetrabromobisphenol-A and polyhalogenated aliphatic ether derivatives used. It has been found that such compositions possess poor thermal stability.
Thus, while in many cases effective flame retardancy can be achieved by various flame retardant additives, one or more other properties of the resultant polymer compositions, such as thermal stability, may be sacrificed. In particular, a need exists for a new, effective flame retardant having high thermal stability for use in thermoplastic polymers and little, if any, tendency to bloom when used in polyolefin polymers.
Thus a welcome contribution to the art of would be the provision of new additive compositions of enhanced thermal stability that have the capability, when blended with suitable thermoplastic polymers, of providing thermoplastic polymer compositions having enhanced thermal stability, especially if this could be accomplished on an economically-attractive basis. It would also be very welcome contribution to provide an effective thermally-stable flame retardant additive composition which has little, if any, blooming tendency when used in blends with polyolefins. This invention is deemed to constitute such a contribution.
Provided by this invention in one of its embodiments is a flame retardant additive composition which comprises a mixture of:
a) (i) at least one polybromodiphenylalkane in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule and in which the alkane portion of the molecule contains 1 to 3 carbon atoms, preferably 2 carbon atoms or (ii) at least one polybromodiphenyl oxide in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule, or (iii) a mixture of (i) and (ii); and
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether);
wherein a) and b) are in proportions such that per each 100 parts by weight of a) and b), 50 to 80 parts by weight are a) and 50 to 20 parts by weight are b). Thus contrary to the teachings of the above Japanese Kokai, in this embodiment of the invention the amount by weight of component a) used is at least the same as, or more than, the amount of component b).
A preferred embodiment is a flame retardant additive composition which comprises a mixture of:
a) (i) at least one polybromodiphenylalkane in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule and in which the alkane portion of the molecule contains 1 to 3 carbon atoms, preferably 2 carbon atoms or (ii) at least one polybromodiphenyl oxide in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule, or (iii) a mixture of (i) and (ii);
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether); and
c) at least one synthetic zeolite or at least one hydrotalcite, or both;
wherein a) and b) are in proportions such that per each 100 parts by weight of a) and b), 20 to 80 parts by weight are a) and 80 to 20 parts by weight are b), and wherein c) is in an amount such that there is one part by weight thereof per each 4 to 6 parts by weight of b) in the composition. As between the zeolite(s) and the hydrotalcite(s), use of the synthetic zeolite as c) is more preferred. As will be seen hereinafter, the presence of component c) greatly enhances the thermal stability of the compositions and thus makes possible, inter alia, use of proportions described in the above Japanese Kokai with satisfactory results.
In another preferred embodiment there is provided a flame retardant additive composition which comprises a mixture of:
a) at least one polybromodiphenylalkane in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule and in which the alkane portion of the molecule contains 1 to 3 carbon atoms, preferably 2 carbon atoms; and
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether);
wherein a) and b) are in proportions such that per each 100 parts by weight of a) and b), 50 to 80 parts by weight are a) and 50 to 20 parts by weight are b).
Still another preferred embodiment is a flame retardant additive composition which comprises a mixture of:
a) at least one polybromodiphenylalkane in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule and in which the alkane portion of the molecule contains 1 to 3 carbon atoms, preferably 2 carbon atoms;
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether);
c) at least one synthetic zeolite or at least one hydrotalcite, or both;
wherein a) and b) are in proportions such that per each 100 parts by weight of a) and b), 20 to 80 parts by weight are a) and 80 to 20 parts by weight are b), and wherein c) is in an amount such that there is one part by weight thereof per each 4 to 6 parts by weight of b) in the composition. As between the zeolite(s) and the hydrotalcite(s), use of the synthetic zeolite as c) is more preferred.
Yet another embodiment of this invention is a flame retardant additive composition which comprises a mixture of:
a) at least one polybromodiphenyl oxide in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule; and
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether);
wherein a) and b) are in proportions such that per each 100 parts by weight of a) and b), 50 to 80 parts by weight are a) and 50 to 20 parts by weight are b).
A further embodiment of this invention is a flame retardant additive composition which comprises a mixture of:
a) at least one polybromodiphenyl oxide in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule;
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether); and
c) at least one synthetic zeolite or at least one hydrotalcite, or both;
wherein a) and b) are in proportions such that per each 100 parts by weight of a) and b), 20 to 80 parts by weight are a) and 80 to 20 parts by weight are b), and wherein c) is in an amount such that there is one part by weight thereof per each 4 to 6 parts by weight of b) in the composition. As between the zeolite(s) and the hydrotalcite(s), use of the synthetic zeolite as c) is more preferred.
Further embodiments of this invention include a flame retardant polymer composition comprised of at least one thermoplastic polymer with which has been blended, separately or in combination, a flame-retardant amount of:
a) (i) at least one polybromodiphenylalkane in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule and in which the alkane portion of the molecule contains 1 to 3 carbon atoms, preferably 2 carbon atoms or (ii) at least one polybromodiphenyl oxide in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule, or (iii) a mixture of (i) and (ii); and
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether);
in proportions such that per each 100 parts by weight of a) and b), 50 to 80 parts by weight are a) and 50 to 20 parts by weight are b). Preferably such polymer composition further contains as component c) at least one synthetic zeolite or at least one hydrotalcite, or both, in an amount such that there is one part by weight thereof per each 4 to 6 parts by weight of b) blended with said thermoplastic polymer. When component c) is used, components a) and b) can be in proportions such that per each 100 parts by weight of a) and b), 20 to 80 parts by weight are a) and 80 to 20 parts by weight are b). As between the zeolite(s) and the hydrotalcite(s), use of the synthetic zeolite as component c) is more preferred. Still further embodiments are each of the flame retardant polymer compositions as described in this paragraph wherein a) is (i) thereof. Additional embodiments are each of the flame retardant polymer compositions as described in this paragraph wherein a) is (ii) thereof.
Still additional embodiments include a method of flame retarding a thermoplastic polymer, which method comprises blending with such polymer, separately or in combination, a flame-retardant amount of:
a) (i) at least one polybromodiphenylalkane in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule and in which the alkane portion of the molecule contains 1 to 3 carbon atoms, preferably 2 carbon atoms or (ii) at least one polybromodiphenyl oxide in which the phenyl groups are substituted by a total of at least 6 bromine atoms per molecule, or (iii) a mixture of (i) and (ii); and
b) at least one tetrabromobisphenol-A-bis(bromoalkyl ether);
in proportions such that per each 100 parts by weight of a) and b), 50 to 80 parts by weight are a) and 50 to 20 parts by weight are b). Preferably in conducting such method, component c) is also blended with such polymer separately or in combination with a) and/or b), component c) being at least one synthetic zeolite or at least one hydrotalcite, or both, in an amount such that there is one part by weight thereof per each 4 to 6 parts by weight of b) blended with said thermoplastic polymer. When component c) is used, components a) and b) can be in proportions such that per each 100 parts by weight of a) and b), 20 to 80 parts by weight are a) and 80 to 20 parts by weight are b). As between the zeolite(s) and the hydrotalcite(s), use in the blending of the synthetic zeolite is more preferred. Still further embodiments are each of the methods as described in this paragraph wherein a) is (i) thereof. Additional embodiments are each of the methods described in this paragraph wherein a) is (ii) thereof.
Flame retardant molded or extruded articles or shapes made from any of the foregoing flame retardant thermoplastic polymers of this invention, and methods of forming such articles or shapes are still further embodiments of this invention.
In the various embodiments of this invention in which component c) is used, preferably the proportions of components a) and b) are such that per each 100 parts by weight of a) and b), 50 to 80 parts by weight are a) and 50 to 20 parts by weight are b).
In all embodiments of this invention, whether or not component c) is used, more preferred proportions of a) and b) are such that per each 100 parts by weight of a) and b), 60 to 75 parts by weight are a) and 40 to 25 parts by weight are b), and still more preferred proportions of a) and b) are such that per each 100 parts by weight of a) and b), about 70 parts by weight are a) and about 30 parts by weight are b).
In the all of the embodiments of this invention, preferably, component a) is decabromodiphenyl oxide, and more preferably is 1,2-bis(pentabromophenyl)ethane (a.k.a. decabromodiphenylethane). Preferably component b) is tetrabromobisphenol-A-bis(2,3-dibromopropyl ether).
Other embodiments and features of this invention will be still further apparent from the ensuing description, accompanying drawings, and appended claims.