THERMOSTABILITY ENHANCEMENT OF POLYPHOSPHATE FLAME RETARDANTS

Abstract: The thermostability of an aromatic polyphosphate composition can be improved by the addition of an effective amount of a hydroxy-terminated aromatic polyphosphate composition for such.

Description: THERMOSTABILITY ENHANCEMENT OF POLYPHOSPHATE FLAME RETARDANTS BACKGROUND OF THE INVENTION The term "polyphosphate" as used herein is intended to mean a composition of the type to be described in more detail below which contains two or more phosphate moieties in its structure. Aromatic polyphosphate compositions which can be predominantly diphosphate in nature or of higher molecular weight (i.e., oligomeric) and which are not hydroxy-terminated are known to persons of ordinary skill in the art with representative examples being described in European Patent Publication Nos. 509,506 and 521 ,628 and Japanese Patent Publication No. 227,632/1988. A general formula which can be used to represent compositions of this type is the following: O O ArO - (P - O - R - O ) n - P - OAr OAr OAr with Ar being aryl, such as unsubstituted phenyl, R being a hydrocarbyi group such as phenyl, diphenyl, 4,4'-isopropylidenediphenyl, and the like (with a particularly preferred diol being resorcinol) and with n ranging from 1 to about 10. Mixtures where n is a decimal number are also contemplated. An example of a commercially available material of this type containing a bridging group derived from resorcinol is available under the trademark FYROLFLEX ® RDP from Akzo Nobel Chemicals Inc. Hydroxy-terminated aromatic polyphosphate compositions are also known in the art. For example, an oligomeric phosphate is depicted as one of the products formed by the processes described in Japanese Patent Publication No. 223,158/1989. The product that is desired is a mixture of 22%-65%, by weight, of a reactive, hydroxy-terminated monophosphate ester, 15%-30% of a non-reactive, non-hydroxy-terminated phosphate ester, and 5%-63% of a hydroxy-terminated oligomeric phosphate ester. More recent U.S. Patent No. 5,508,462 to D.A. Bright et al. describes and claims a process for making certain hydroxy-terminated aromatic polyphosphate compositions. SUMMARY OF THE INVENTION The present invention relates to a fluid flame retardant composition which comprises an aromatic polyphosphate composition and an effective amount of a hydroxy-terminated aromatic polyphosphate compositions for improvement of the thermostability thereof. DESCRIPTION OF THE PREFERRED EMBODIMENTS It has now been found that a hydroxy-terminated aromatic polyphosphate is an effective thermostability enhancing agent in the aforementioned type of aromatic polyphosphate composition which is not hydroxy-terminated. In general terms, the aromatic polyphosphate composition which is not hydroxy- terminated will be present in major amount in the composition (e.g., from about 99% to about 51%, by weight of the composition, preferably from about 90% to about 70%, by weight of the composition). The desired hydroxy-terminated aromatic polyphosphate product is of the formula: O O HO-R-O - (P - O - R - O ) n - P-O-R-OH OAr OAr with Ar and R being defined as given above, and with n ranging from about 1 to about 20. The hydroxy-terminated aromatic polyphosphate composition can be made as described in US 5,508,462. More, specifically in an initial process step a monophenyl dihalophosphate is reacted with an aromatic diol to form a halo-terminated aromatic oligomeric phosphate. The monophenyl dihalophosphate is of the formula ArOP(O)X 2 , where Ar stands for substituted or unsubstituted phenyl and X stands for halo, such as chloro or bromo. A preferred reagent to use is monophenyl dichlorophosphate. The aromatic diol is of the formula HOROH, with R being a hydrocarbyi group such as phenyl, diphenyl, 4,4'-isopropylidenediphenyl, and the like. A particularly preferred diol is resorcinol. Others which can be used include hydroquinone, bisphenol A, bisphenol S, and 4,4-diphenol. This initial reaction step is preferably conducted at an elevated temperature of about 50°C to about 130°C using an effective abount (about 0.1% to about 0.5%, by weight of the dihalphosphate) of a Lewis acid catalyst, such as magnesium dichloride. The resulting halo-terminated product from this reaction is an aromatic oligomeric phosphate of the following formula: O O X - (P-O-R-O) n P - X OAr OAr With Ar and X being defined as earlier described and n ranging from 1 to about 10. Mixtures where n is a decimal number are also contemplated. This halo-terminated reaction product is then reacted with additional diol in a subsequent reaction step to substitute the halo-termination with the HO-R-O- group from the diol to yield the desired hydroxy-terminated aromatic oligomeric phosphate product: O O HO-R-O-(P-O-R-O) n - P - O - R - OH OAr OAr This second reaction step is also preferably conducted at an elevated temperature of about 110°C to about 180°C. The present invention is illustrated by the Examples which follow. EXAMPLES Varying amounts of an oligomeric resorcinol-based polyphosphate flame retardant (available under the trademark FYROLFLEX ® RDP from Akzo Nobel Chemicals Inc.) and the analogous hydroxy-terminated composition described and claimed in U.S. Patent No. 5,508,462 were mixed together by solution blending in the amounts indicated in the Table set forth below (i.e., 20 wt%, 50 wt%, and 80 wt% of the hydroxy-terminated composition. The thermostability of the blends were tested at the temperatures also given in the table using a PERKIN ELMER TGA-7 thermogravimetric analyzer, in air, at a heating rate of 10°C per minute. The effect of blending the various amounts of the hydroxy- terminated composition were determined as an increase in retained weight for the system at the given temperature. The data given in the Table sets forth three., sequential numerical values when the hydroxy-terminated composition was present in the blends that were tested: the actual determination of the percentage of original bisphosphate material that was retained after the thermogravimetric analysis; the expected retained weight of bisphosphate that was calculated using the rule of mixtures; and the percentage increase for the experimental retained weight value as compared to the calculated value: Retained Weight of Blends * (%) - - Temp.fC, 100/0 * 80/20 50/50 20/80 0/100 400 54 70/59/19 " 77/65/18 75/72/4 77 460 14 44/26/70 63/38/66 70/60/17 72 500 4.3 35/17/106 57/37/54 67/57/18 70 560 3.5 31/15/107 48/33/45 58/50/16 62 600 3.0 29/14/107 44/30/47 53/46/15 57 700 1.4 21/10/110 31/23/35 39/37/5 44 780 0.2 15/7/114 22/17/29 22/17/29 34 * the weight ratio of the FYROLFLEX ® RDP brand polyphosphate flame retardant to the hydroxy-terminated polyphosphate component. ** the first number gives the wt% residue, experimental; the second number gives the wt% residue, calculated; and the third number gives the % increase in residue comparing the experimental value to the calculated value. The data indicate that the addition of the hydroxy-terminated composition to the FYROLFLEX ® RDP brand polyphosphate flame retardant enhanced the thermostability of that product and that the weight loss of the resulting product blend was thereby reduced. All of the blends showed a higher residual weight over calculated values. The most pronounced effect was noted for the blend containing 20 wt% of the hydroxy-terminated composition. At 500°C, the blend produced a 35 wt% residue, giving a 106% increase, as compared to the expected 17 wt% residue expected from the 80% contribution of the neat FYROLFLEX ® RDP brand polyphosphate flame retardant (a baseline 4.3 wt% residue value for the neat material) added to the 20% contribution from the hydroxy-terminated composition (a baseline 70 wt% residue value for the neat material). As a result the volatility of the FYROLFLEX ® RDP brand polyphosphate flame retardant was substantially reduced and its decomposition is at least partially shifted to the condensed phase. The foregoing Examples are provided to illustrate certain embodiments of the present invention and, for that reason, should not be construed in a limiting sense. The scope of protection sought is set forth in the Claims which follow.

Claims: Claims 1. A fluid flame retardant composition comprising 1 - 49 percent by weight, based on the weight of the total composition, of a hydroxy-terminated aromatic polyphosphate composition, the remainder essentially being a non-hydroxy-terminated aromatic polyphosphate composition. 2. A composition according to claim 1 wherein the non-hydroxy-terminated aromatic polyphosphate composition consists predominantly of aromatic polyphosphates of the formula O O ArO - (P - O - R - O ) n - P - OAr OAr OAr with Ar being aryl, R being a hydrocarbyi group, and with n ranging from 1 to about 10. 3. A composition as claimed in Claim 1 wherein the hydroxy-terminated aromatic polyphosphate composition is of the formula: O O HO-R-O-(P-O-R-O) n - P - O - R - OH OAr OAr with Ar being aryl, R being a hydrocarbyi group, and with n ranging from 1 to about 20. 4. A composition as claimed in Claim 1 wherein the flame retardant composition comprises a major amount of an aromatic polyphosphate composition of the formula O O ArO - (P - O - R - O ) n - P - OAr OAr OAr with Ar being aryl, R being a hydrocarbyi group, and with n ranging from 1 to about 10 and wherein the hydroxy-terminated aromatic polyphosphate composition is of the formula: O O HO-R-O-(P-O-R-O) n - P - O - R - OH OAr OAr with Ar being aryl, R being a hydrocarbyi group, and with n ranging from 1 to about 20. 5. A composition according to any one of the preceding claims wherein the amount of hydroxy-terminated aromatic polyphosphate composition is from 10 to 30 percent by weight, based on the weight of the total composition. A. CLASSIFICATION OF SUBJECT MATTER IPC 6 C09K21/12 C07F9/12 According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC 6 C09K C07F Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and, where practical, search terms used) C DOCUMENTS CONSIDERED TO BE RELEVANT Category ° Citation ot document, with indication, where appropriate, of the relevant passages Relevant to claim No US 5 508 462 A (D.A. BRIGHT) 16 April 1996 1 , 3 see col umn 2 , l i ne 4 - l i ne 22 PATENT ABSTRACTS OF JAPAN 1,3 vol . 013 , no . 546 (C-661 ) , 6 December 1989 & JP 01 223158 A (AJIN0M0T0 CO INC), 6 September 1989 cited i n the appl i cati on see abstract EP 0 521 628 A (ETHYL PETROLEUM ADDITIVES 1,2 INC ) 7 January 1993 cited i n the appl icati on see page 2 , l i ne 8 - l ine 25 see page 3 , l ine 3 - l ine 9 -/-- Further documents are listed in the continuation of box C Patent family members are listed in annex ° Special categories of cited documents ■ T" later document published after the international filing date "A" document defining the general state of the art which is not or pnonty date and not in conflict with the application but considered to be of particular relevance cited to understand the principle or theory underlying the invention "E" earlier document but published on or after the international filing date "X" document of particular relevance, the claimed invention cannot be considered novel or cannot be considered to "L" document which may throw doubts on pnonty claιm(s) or involve an inventive step when the document is taken alone which is cited to establish the publication date of another citation or other special reason (as specified) "Y" document of particular relevance, the claimed invention cannot be considered to involve an inventive step when the "O" document referπng to an oral disclosure, use, exhibition or document is combined with one or more other such docuother means ments, such combination being obvious to a person skilled "P" document published prior to the international filing date but in the art later than the pnonty date claimed "&" document member of the same patent family Date of the actual completion of the international search Date of mailing of the international search report 15 January 1999 21/01/1999 Name and mailing address of the ISA Authorized officer European Patent Office, P B 5818 Patentlaan 2 NL - 2280 HV Ri|swi|k Tel (+31-70) 340-2040, Tx 31 651 epo nl, Fax. (+31-70) 340-3016 Boul on , A Form PCT/ISA210 (second sheet) (July 1992) a e 1 of 2 C.(Continuation) DOCUMENTS CONSIDERED TO BE RELEVANT Category * Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. PATENT ABSTRACTS OF JAPAN 1,2 vol. 013, no. 024 (C-561), 19 January 1989 & JP 63227632 A (DAIHACHI KAGAKU K0GY0SH0:KK), 21 September 1988 cited in the application see abstract EP 0646 587 A (CIBA-GEIGY) 5 April 1995 1-3 see claims 1-11; example 1 Form PCT/ISA/210 (continuation of second sheet) (July 1992) a e 2 of 2 Information on patent family members PCT/EP 98/05722 Patent document Publication Patent family Publication cited in search report date member(s) date US 5508462 16-04-1996 CA 2206130 A 13-06-1996 EP 0796265 A 24-09-1997 JP 10510269 T 06-10-1998 WO 9617854 A 13-06-1996 EP 521628 07-01-1993 AU 655284 B 15-12-1994 AU 1814992 A 17-12-1992 CA 2070131 15-12-1992 DE 69209168 25-04-1996 DE 69209168 25-07-1996 JP 5194559 03-08-1993 US 5344468 06-09-1994 CA 2070123 15-12-1992 EP 646587 05-04-1995 CA 2131580 A 10-03-1995 JP 7165773 A 27-06-1995 US 5506313 A 09-04-1996 Form PCT/ISA210 (patent family annex) (July 1992)

Inventors: BRIGHT DANIELLE ANGRAND, DASHEVSKY SOPHIA, BRIGHT, DANIELLE, ANGRAND, DASHEVSKY, SOPHIA
Applicants: AKZO NOBEL NV, AKZO NOBEL N.V.
Application year: 1998
Main classification: C09K21
IPC codes: C07F9, C09K21