Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-12-04
2003-09-09
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S421000, C524S424000, C524S495000
Reexamination Certificate
active
06617379
ABSTRACT:
TECHNICAL FIELD
This invention relates to flame retardant compositions of enhanced effectiveness in which N,N′-piperazinebis(neopentylglycol)phosphoramidate is utilized as a component. More particularly this invention relates to the use of certain additives in combination with N,N′-piperazinebis(neopentylglycol)phosphoramidate and the use of such combinations in polymers, especially thermoplastic polymers, whereby achievement of enhanced flame retardancy is made possible.
BACKGROUND
U.S. Pat. Nos. 5,973,041, 6,221,939 B1 and 6,228,912 B1 show in Example 1 thereof that although N,N′-piperazinebis(neopentylglycol)phosphoramidate (a.k a. N,N′-bis(neopentylenedioxyphosphoryl)piperazine) exhibited satisfactory high temperature properties in polycarbonate as indicated by glass transition temperature (Tg) measurement, this compound was unsatisfactory as a flame retardant as it resulted in an unacceptably high total flame out time (FOT).
It would be of advantage if a way could be found of enhancing the effectiveness of N,N′-piperazinebis(neopentylglycol)phosphoramidate as a flame retardant. This invention is deemed to fulfill this objective in an effective manner.
BRIEF SUMMARY OF THE INVENTION
This invention involves the discovery, inter alia, that despite the poor flame retardancy performance of N,N′-piperazinebis(neopentylglycol)phosphoramidate (a.k.a. N,N′-bis(neopentylenedioxyphosphoryl)piperazine) as reported by the above three U.S. patents, combinations of this compound together with a melamine compound, make it possible to provide polymer blends having substantially improved flame retardant properties.
Moreover, in preferred embodiments this invention makes it possible to provide highly economical thermoplastic compositions that are entirely free of the environmental concerns attributed to halogen-containing additives and also antimony-containing components often used in polymeric materials. In addition, this invention makes it possible to provide flame retarded thermoplastic compositions in which the physical properties needed for end use applications are not materially impaired. In fact, in certain preferred embodiments, compositions having increased melt flow properties are provided.
Accordingly, this invention provides in one of its embodiments a flame retardant additive composition which comprises a blend of the following:
a) N,N′-piperazinebis(neo-pentylglycol)phosphoramidate; and
b) at least one co-additive which is (i) melamine, (ii) one or more melamine compounds, or (iii) both of (i) and (ii).
Another embodiment is a resin composition comprising a thermoplastic polymer with which has been blended, singly and/or in admixture, a flame retardant amount of:
a) N,N′-piperazinebis(neopentylglycol)phosphoramidate; and
b) at least one co-additive which is (i) melarnine, (ii) one or more melamine compounds, or (iii) both of (i) and (ii).
Preferably, but not necessarily, the above additive composition and resin compositions are halogen-free (as defined herein) and also antimony-free.
A further embodiment is a flame retardant resin composition comprising:
A) an acid-sensitive thermoplastic polymer;
B) N,N′-piperazinebis(neopentylglycol)phosphoramidate that is free or essentially free of acid species; and
C) at least one co-additive which is (i) melamine, (ii) one or more melamine compounds, or (iii) both of (i) and (ii);
and/or any resultant reaction product or products thereof that are present in said composition.
The thermoplastic polymer compositions of this invention are characterized in that they are able to provide standard test specimens for the UL 94 test procedure having or giving at least a V-2 rating in said test procedure with standard test specimens of at least one of the following thicknesses: (1) {fraction (1/16)}-inch thickness or (2) ⅛-inch thickness. Preferred compositions are those as just described in which the standard test specimens for the UL 94 test procedure of at least one of the thicknesses of (1) or (2) have or give a V-0 rating in that test procedure. Most preferably specimens of both such thicknesses have or give a V-0 rating. The UL 94 test procedure referred to herein is the procedure as published in Underwriters Laboratories Inc. Standard for Safety UL-94 “Test for Flammability of Plastic Materials for Parts in Devices and Appliances”.
Other embodiments of the invention exist, and will be further apparent from the ensuing description and the appended claims.
FURTHER DETAILED DESCRIPTION
A number of melamine compounds are deemed suitable for use in the practice of this invention. In this connection, by “melamine compound” or “melamine compounds” is meant an additive compound or additive compounds having at least one 6-membered triazine ring or moiety therein in which at least one amino nitrogen atom is directly bonded to at least one such triazine ring on a carbon atom of the ring. When the melamine compound contains more than one such ring or moiety, the rings or moieties can be in the form of fused ring structures (as in melem or melon) or unfused ring structures (as in melam). One type of candidate melamine compounds for use as co-additives of this invention are melamine and N-hydrocarbyl or N-halohydrocarbyl derivatives of melamine of the general formula:
where each R is, independently, a hydrogen atom, a C
1-6
alkyl group, a C
5-6
cycloalkyl group, C
1-6
haloalkyl group, a C
5-6
halocycloalkyl group, a C
6-12
aryl group, or a C
6-12
haloar C
7-12
aralkyl group, or a C
7-12
haloaralkyl group. A few non-limiting examples of this type of melamine compounds include melamine, N-methylmelamine, N-cyclohexylmelamine, N-phenylmelamine, N,N-dimethylmelamine, N,N-diethylmelamine, N,N-dipropylmelamine, N,N′-dimethylmelamine, N,N′,N″-trimethylmelamine, N-trifluoromethylmelamine, N-(2-chloroethyl)melamine, N-(3-bromophenyl)melamine, and the like. Also alcohol derivatives of melamine such as trimethylolmelamine or triethylolmelamine may be used. Melamine sulfate and melamine phosphates such as melamine orthophosphate, melamine polyphosphate, and dimelamine orthophosphate may also be used. Another useful melamine compound is melammonium pentate (i.e., the dimelamine salt of pentaerythritol diphosphate). Still other melamine compounds that may be used are melam, melem, and melon. Preferred melamine compounds are melamine pyrophosphate and melamine cyanurate, each of which is available commercially. Melamine can be used singly or in admixture with one or more other melamine compounds, provided the mixture is effective as a flame retardant. Likewise melamine compounds may be used singly or as mixtures of two or more melamine compounds, provided the mixture is effective as a flame retardant. Methods for the preparation of melamine compounds are known and reported in the literature. See for example U.S. Pat. No. 4,298,518; Kirk-Othmer
Encyclopedia of Chemical Technology
, Fourth Edition, volume 7, pages 748-752; Id., volume 10, page 980; and E. Prill,
J. Am. Chem. Soc
., 1947, 69, 62.
A method for the preparation of N,N′-piperazinebis(neopentylglycol)phosphoramidate (hereinafter sometimes referred to as PBNGP) has been reported in Japan Kokai 54/019919. A more practical process is described hereinafter.
It has been found that when using PBNGP as a flame retardant in an acid-sensitive substrate or host polymer such as polybutylene terephthalate, the presence of excessive acid species in the PBNGP can result in severe degradation of properties of the molded polymer, such as color, tensile strength, or the like. Such acid species can include free acids such as HCl or HBr, amine hydrohalide, and/or any acid or acidic impurities resulting for example from hydrolysis and/or other transformations occurring in the PBNGP product or the starting materials used in its synthesis. There are different ways of combating this adverse situation. One way is to add a sufficient amount of one or more acid scavenger additives to the polymer blend to negate the adverse effects of t
De Schryver Daniel A.
Landry Susan D.
Mack Arthur G.
Worku Anteneh Z.
Albemarle Corporation
Sanders Kriellion A.
Spielman, Jr. Edgar E.
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