GB1562616A - Thermoplastic blends - Google Patents

Description

(54) IMPROVEMENTS IN THERMOPLASTIC BLENDS (71) We, GENERAL ELECTRIC COMPANY, a corporation organized and existing under the laws of the State of New York, United States of America, of 1 River Road, Schenectady 12305, State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to thermoplastic blends of a thermoplastic polymer and a dihydrooxadiazinone. More particularly, the present invention relates to foamable compositions, a method for making a thermoplastic foam and foamed structures made therefrom.

Prior to the present invention, the plastics industry expended considerable effort towards the study and development of high performance thermoplastics foams for the purpose of making lightweight structural substitutes for metal in various applications such as used in the automotive industry. As shown in U.S.

patent 3,888,801, hydrazodicarboxylates have commonly been employed as blowing agents for various thermoplastic organic polymers for the purpose of reducing the overall weight of particular thermoplastic materials when molded to a specific shape. Other blowing agents, which are commonly used with various thermoplastlc organic polymers, are 5-phenyltetrazole, benzamides, etc., as shown by Muller et al, U.S. Patent 3,781,233, and Wirth et al, U.S. Patent 3,779,954.

Although hydrazodicarboxylates, such as diisopropyl hydrazodicarboxylate and 5phenyltetrazole have been found effective for reducing the density of various thermoplastic organic polymers, such as polycarbonates, polyesters and polyacrylates it has been shown that a significant degree of polymer degradation can occur during the foaming process. Polymer degradation is generally evidenced by a reduction in the intrinsic viscosity of the polymer when a comparison of polymer intrinsic viscosity is made before and after foaming. Polymer degradation is also directly related to reduction in foam impact strength.

Although it is not completely understood, one possible explanation as to why blowing agents, such as the above-described hydrazodicarboxylates can cause a significant degree of polymer degradation upon foaming, is that such blowing agents have decomposition by-products such as aliphatic alcohols, ammonia, water, etc.

Blowing agents such as the above-described benzazimides and bisbenzazimides are also polymer degradation prone, since water is a decomposition by-product. Those skilled in the art know that careful drying of high performance thermoplastics, such as polycarbonates, is required prior to molding because of possible risk of polymer degradation. It would be desirable, therefore, to provide blowing agents which can be employed in a variety of high performance thermoplastic organic polymers, such as polyesters, and polycarbonates, which do not degrade the thermoplastic polymer and which resist an adverse reduction in impact strength of the foam product beyond that normally expected from the change in the density of the material as the result of foaming.

The present invention is based on the discovery that dihydrooxadiazonones having maximum decomposition rates at temperatures in the range of between 1700C to 3100 C, such as are shown by M. Rosenblum et al., J. Amer. Chem. Soc., 85, 3874 (1963), can be employed in a variety of organic thermoplastic polymers such as polycarbonates, polyesters, and others more particularly exemplified hereinafter to produce blends which can be injection molded to various foamed shapes without effecting a significant change in organic polymer intrinsic viscosity or stiffer a more than normal reduction in impact strength of the foamed structure.

There is provided by the present invention, an injection moldable foamable compositions comprising a blend of a thermoplastic organic polymeric material and based on the weight of the composition 0.1 to 25 per cent of a dihydrooxadiazinone having a maximum decomposition rate in the range between 170"C and 310"C, said thermoplastic organic polymeric material being capable of being molded at least twice at a temperature of 150"C to 4000 C.

Included by the -6hydrooxadiazinones which can be employed in making the blends of the present invention are compounds having the formula

where "a" is an integer equal to 1 or 2, R is a monovalent radical when "a"-is 1, and a divalent radical when "a" is 2, selected from a Cm,~" alkyl radical or alkylene radical, a C/,,~30) aryl radical or arylene radical and halogenated derivatives thereof.

R1 and R2 are the same or different monovalent atoms or radicals selected from hydrogen, C(19) alkyl, alkylene, C( ,~30} aryl, arylene, alkoxy, aryloxy and where R' and R2 are both alkyl, they can be- part of a cycloaliphatic ring structure.

Radicals included by R Formula 1 are C1,~8 alkyl radicals, such as methyl, ethyl propyl and butyl; aryl radicals such aspenyl, tolyl, xylol, napthyl and anthryl; halo alkyls such as chloroethyl, trifluoropropyl, halo aryls such as chlorophenyl and bromotolyl; nitroaryls and sulfoaryls. Atoms or radicals included by R1 and R2 are hydrogen, and C"~8, alkyl radical such as methyl; ethyl, and propyl; alkoxy radicals such as methoxy, ethoxy, propoxy and butoxy, aryloxy radicals such as phenoxy, cresoxy and napthoxy. In particular instances where R' and R2 are both alkyl they can be part of a cycloaliphatic ring structure such as cyclopehtyl, cyclohexyl, cycloheptyl. In other situations where R1 and R2 are both aryl, they can be phenyl, tolyl, xylyl, napthyl, anthryl, or a mixture of any two of the aforementioned aryl radicals.

Some of the dihydrooxadiazinones which can be used in the practice of the invention are, for example, 5 ,6-dimethyl-3,6-dihydro- 1 ,3,4-oxadiazin-2-one 5,6,6-trimethyl-3,6-dihydro- 1 ,3,4-oxadiazin-2-one 5-ethyl-6-methoxy-3 ,6-dihydro- 1,3 ,4-oxadiazin-2-one 5 ,6-diphenyl-3,6-dihydro- 1,3 ,4-oxadiazin-2-one 5-(p-bromophenyl)-3 ,6-dihydro- 1 ,3,4-oxadiazin-2-one 5-phenyl-6-methyl-3 ,6-dihydro- 1,3 ,4-oxadiazin-2-one 5,6-bis(p-methoxyphenyl)-3,6-dihydro- 1,3,4-oxadiazin-2-one 5-naphthyl-3,6 ,6-dihydro- 1, 3,4-oxadiazin-2-one 5-(o,o,p-tribromophenyl)-6-propyl-3,6-dihydro- 1,3 ,4-oxadiazin-2-one 5-(p-hydroxyphenyl)-3 ,6-dihydro- 1,3,4-oxadiazin-2-one 5-phenyl-6,6-cyclopentylene-3,6-dihydro-1,3,4-oxadiazin-2-one 5-(m-nitrophenyl)-3,6-dihydro-l ,3,4-oxadiazin-2-one 5-(p-benzenesulfonic acid sodium salt)-3,6-dihydro- 1,3 ,4-oxadiazin-2-one 5-(2-fluorenylY6-trifluoroethyl-3 ,6-dihydro- 1,3 ,4-oxadiazin-2-one 5-phenyl-6-(cyanophenylmethyl)-3,6-dihydro- 1 ,3,4-oxadiazin-2-one 5-phenyl-6-cyano-6-methyl-3 ,6-dihydro-l ,3,4-oxadiazin-2-one and such polycyclic formulas resulting from divalent substitution as

R', R2 and R are as defined above.

The term "thermoplastic polymeric material" is defined as any organic polymer which can be injected molded at least twice at a temperature in the range of from 1500C to 400"C such as polycarbonates, polyesters, such as polybutylene terephthalate, polyethylene terephthalate, polybutylene-terephthalate-poly- butyleneoxide copolymers, poly(4,4-cyclohexylidene-diphenylene isophthalate), poly(4,4-isopropylidenediphenylene isophthalate), poly(-p-hydroxybenzoic acid), such as poly(hexafluoropropylene) polyolefins, such as polypropylene, polyacrylates and polymethacrylates, polystyrenes poly(4-tert-butylstyrene), poly (4-bromostyrene), poly(a-methyl-styrene), polyamides such as polycaprolactam and poly-hexamethyleneadipamide, polyvinylchloride, polyphenylene oxide based resins, including blends with polystyrene, polyarylsulfones, ABS polymers, polystyrene acrylonitrile copolymers, polyacetals, urethane elastomers, polyphenylene sulfide, polymides, polysilphenylenes; also various copolymers, block copolymers, polymer blends and alloys of the components mentioned above.

In the practice of the invention, the thermoplastic compositions can be made in the form of for example a dry powder, in an extruded pelletized form or in the form of an extruded thermoplastic sheet, based on the melt characteristics of the thermoplastic polymeric material and the decomposition temperature of the blowing agent. In instances where the decomposition temperature of the blowing agent, which hereinafter will be used interchangeable with the term "dihydrooxadiazinone," is below or about the temperature at which the thermoplastic polymeric material can be melt extruded or slightly above, it is preferred to make the thermoplastic composition in the form of a dry powder. Blowing agents exhibiting maximum decomposition rates at temperatures at least 25"C greater than the melt extrusion temperature of the thermoplastic polymeric material can provide for extrudable foamable compositions or concentrates, having from 1% to 25% by weight or more of blowing agent based on the weight of blowing agent and thermoplastic polymer material, can be further melt extruded with additional thermoplastic polymeric material to make foamable compositions. Melt extruded pellets or sheets having from 0.1 to 1.0% by weight of dihydroxadiazinone, can be converted to foam structures at higher injection molding temperatures. The decomposition temperatures of the blowing agents used in the practice of the present invention to make foamable thermoplastic blends have maximum decomposition rates in the range of between 1700 to 3100C. A particular preferred combination of blowing agent and thermoplastic polymeric material either in the form of a concentrate or foamable blend is a combination of polycarbonate resin, referred to commercially as LEXAN* polycarbonate resin, with 5-phenyl-3,6-dihydro- 1,3,4- oxadiazin-2-one as a blowing agent. A class of preferred thermoplastic organic blends convertible to high performance foams in accordance with the practice of the invention utilized high performance thermoplastic organic polymer in combination with a dihydrooxadiazinone of the formula (* Lexan is a Registered TradeMark of General Electric Company. USA)

where R3 is a monovalent or divalent C(6~30, aryl radical within the scope of dihydrooxadiazinones. Preferred blends can be in the form of a powder, pellet or sheet with an organic polymer selected from a polycarbonate, polyphenylene oxide, polyphenylene oxide-polystyrene blends, polyarylsulfone, polyimide and polycarbonate polymers resulting from the phosgenation or ester interchange of 1,1dichloro-2,2-bis(4-hydroxyphenyl)ethylene, or polyesters derived from such dihydricphenof, as well as polyamides. The latter thermoplastic organic polymers which are based on the use of 1,1 -dichloro-2,2-bis(4-hydroxyphenyl)ethylene can provide for the production of high performance thermoplastic foams. An example of the use of such chloral derived dihydric phenol is shown by Zbigniew Dobkowski et al., Synthesis of Polycarbonates by Interfacial Method, Polymery Tworzywa Wielkocasteczkowe (1970).

Another preferred thermoplastic foamable blend which can be employed in the practice of the invention is based on the use of 3,6-dihydro-5,6-diphenyl-1 3,4-.

oxadiazin-2-one, reported by M. Rosenblum et al., Chemistry and Industry, Page 1480 (December 15, 1956), which is shown as follows:

The diphenyl substituted dihydrooxadiazinone is preferably utilized in combination with any one or more of the aforementioned thermoplastic organic polymers having desirable melt characteristics and particularly polyalkylene terephthalate esters, such as polybutylene terephthalate esters in the form of melt extruded pellets, or melt extruded thermoplastic sheet.

The thermoplastic blends of the present invention also can contain other active or inactive fillers, for example, carbon black, fiber glass, chalk, antioxidants, stabilizers, such as salts of lead, cadmium, calcium, zinc, tin, or barium, waxes, dyes, pigments and zinc oxides.

In addition to the above-described thermoplastic blends in pelletized, powder or sheet form, the present invention is also directed to foamed shaped structures derived from the aforementioned blends by conventional injection molding techniques and the like which foamed thermoplastic structures have improved impact strength.

In order that those skilled in the art will be better able to practice the invention, the following examples are given by way of illustration. All parts and percentages are by weight.

Example 1.

A dihydrooxadiazinone used as a blowing agent in the preparation of thermoplastic blend as described below and more particularly 5-phenyl-3,6dihydro-1,3,4-oxadiazin-2-one was prepared as follows: About 13 parts of bromine was added with stirring to a mixture of 474.6 parts of acetophenone in about 640 parts of methanol, while the mixture was stirred and maintained at a temperature between 5--10"C. Hydrogen bromide gas was then introduced into the mixture until bromine coloration disappeared, at which point an additional amount of bromine was added over a 2 hour period to make a total of 631.3 parts. There was then added 71 parts of water while the mixture was stirred and externally cooled for a period of about 30 minutes. An excess of about 2700 parts of water was then slowly added to effect the precipitation in the form of crystals of a-bromo acetophenone from the mixture. The crystals were decanted by means of a vacuumed siphon, washed, then neutralized with a 20% by weight sodium hydroxide aqueous solution, and decanted to dryness. There was then added about 940 parts water, 1600 parts of methanol, 333 parts of sodium bicarbonate and a sodium formate aqueous solution prepared from 161 parts of a 90 /O by weight formic acid and sufficient sodium hydroxide to neutralize the acid.

The mixture was heated at 600C with vigorous stirring for 7 hours after which time it was cooled to ambient temperatue and filtered. Based on method of preparation and gas chromotographic analysis of the mixture, there was produced a-hydroxyacetophenone in quantitative yields.

Dilute aqueous hydrochloric acid was added to the mixture of the above filtrate with 855.8 parts of methyl carbazate which had been prepared from equivalent amounts of hydrazine and dimethyl carbonate. Sufficient hydrochloric acid was used to provide a pH of 5.5 after which the mixture was stirred at 38"C for 6 hours. A crystalline preclpitate was formed which was filtered from the mixture and washed with water. Based on method of preparation and spectroscopic analysis, the product was the carbomethoxy hydrazone of a-hydroxy acetophenone.

A mixture of 570 parts of the above carbomethoxy hydrazone and about 1,900 parts of toluene was refluxed under reduced pressure to effect the removal of residual water from the crystalline product. There was then added 10 parts of anhydrous potassium carbonate to the mixture and the heating was continued under reduced pressure until all of the methanol-toluene azeotrope was removed. The mixture was then allowed to cool to produce the above-described blowing agent 5-phenyl-3,6di- hydro-l,3,4-oxadiazin-2-one which was finally dried in a vacuum oven at ifl800C The overall yield of final product was 456 parts which represented a 65.5% yield based on acetophenone. The melting point of the product was 163-1650C.

Dry powder blends of a Bisphenol-A polycarbonate resin powder having an intrinsic viscosity on the average of about 0.55dl/g in chloroform at 250C and a density of about l.l7g(cc with the above described blowing agent of the present invention and a commercially available blowing agent isopropyl hydrazo dicarboxylate were prepared consisting respectively of 0.6 parts of blowing agent per 100 parts of the polycarbonate resin. The polycarbonate resin was in the form of a finely divided powder which had been dried at 1250C for 16 hours. The aforementioned blends were melt extruded at temperatures in the range of from about 282"C to 3050C. During melt extrusion thermoplastic foam was formed from the aforementioned finely divided dry blends. In addition to melt extruding the aforementioned foamable blends there was also melt extruded the same polycarbonate resin free of blowing agent. The density (g/cc) of the respective blends and the resin free of blend was measured from samples extruded over the range of between 282"C to 305 C. The intrinsic viscosity of the polycarbonate resin and the intrinsic viscosity in chloroform at 250 C of the polycarbonate resin and the aforementioned blends was also measured from samples extruded over the range of between 282"C to 3220C to determine the reduction in molecular weight if any during the foaming process as a result of polymer degradation. The following table shows the result obtained, where "T" is in "C, "Density" shows the change effected over a temperature as a result of "foaming", "IV" shows the change in intrinsic viscosity if any, of the polycarbonate resin as a result of polymer degradation due to byproducts of the blowing agent, where Blend A contains the dihydrooxadiazinone In accordance with the present invention and Blend B contains the isopropyl hydrazodicarboxylate: TABLE I Density (g/cc) Poly T( C) carbonate Blend A Blend B 282 1.17 1.18 1.15 293 ---- 1.03 0.82 299 0.80 305 1.13 .86 0.70 316 1.14 321 Intrinsic Viscosity (dug) Poly T(OC) carbonate Blend A Blend B 282 0.57 0.57 0.55 293 0.56 0.57 299 0.48 305 0.54 0.53 0.46 316 0.54 321 0.52 - The above results show that the molding temperature of the dihydrooxadiazinone of the present invention Blend A is somewhat higher than the molding temperature of the isopropylhydrazodicarboxylate Blend B. More significant, however, is the showing that the blowing agent of the present invention does not significantly change the intrinsic viscosity of the polycarbonate as the result of the foaming action. The polymer extruded with the isopropylhydrazodicarboxylate blowing agent of the prior art shows a 15% decrease in the intrinsic viscosity of the polymer indicating that significant polymer degradation has occured.

Example 2.

Various dry blended thermoplastic foamable blends were made with polycarbonate pellets containing 5% glass fibers. The polycarbonate resin used to make the glass filled pellets had a density of about 1.2g/cc. The various blends contained about 0.25 part of blowing agent, per 100 parts of the pellets, and included the dihydrooxadiazinone blowing agent of the present invention as shown in Example 1, also the blowing agent of the prior art, as discussed in Example 1, and 5-phenyl-tetrazole, another prior art blowing agent. The various blends were converted to 12" x 12" x 3/8" panels using a Siemag* Structomat foam injection molding machine. The impact strength of the panels were measured by the falling dart method (ASTM D170942T)* all of the resulting panels were found to have a density of 0.85g/cc. The following table shows the impact results obtained from the various panels.

* Registered Trade Mark TABLE II Blowing Agent Impact Values (ft.lb.) 5-phenyl-3,6-dihydro-l ,3,4- > 90 oxadiazin-2-one isopropylhydrazo dicarboxylate 80 5-phenyl-tetrazole 80 Example 3.

The polycarbonate resin blends of Example 2 were converted initially to pellets and thereafter injection molded to test bars to determine Izod Impact Strength (ASTM D256--56). In order to make the test bars from this 5-phenyl tetrazole, it was necessary to injection mold the thermoplastic blend in the form of a pelletpowder mix. The following table shows the results obtained with respect to a comparison of the change in intrinsic viscosity going from the pellets to the bars, as well as the change in unnotched Izod Impact results, IV is as previously defined: TABLE III I.V. (dl/g) Unnotched Blowing Agent Pellets Bars Change Izod (ft-lb) 5-phenyl-3,6-di- 0.46 0.445 3% 16 hydro-l ,3,4-oxa- diazin-2-one isopropylhydrazo 0.46 0.390 15% 9.4 carboxylate 5-phenyl-tetrazole 0.46 0.419 10% 14 The above results show that the foamed panels "bars" suffered significant change in intrinsic viscosity as a result of using different blowing agents. The change in the intrinsic viscosity of the polycarbonate also resulted in a change in unnotched Izod impact when the isopropylhydrazodicarboxylate was used, as compared to the dihydrooxadiazinone of the present invention. Although 5-phenyl tetrazole did not degrade the polycarbonate as severely as the isopropylhydrazodicarboxylate, if was inherently limited to its use in the form of a dry powder blend since its decomposition temperature was not sufficiently high enough to convert it to pelletized form prior to its conversion to the test panel. This clearly shows that the dihydrooxadiazinone blowing agents of the present invention can offer significant advantages with respect to flexibility and fabrication as well as providing thermoplastic foam products having superior impact strength.

Example 4.

Extruded concentrates of 5 parts of the dihydrooxadiazinone blowing agent of Example 1, per 100 parts of polycarbonate resin and 5 parts of isopropylhydrazodicarboxylate per 100 parts of polycarbonate resin, where the concentrates were in pelletized form, were respectively mixed with 19 parts, per part of pelletized concentrate, of a polycarbonate resin containing 5% glass fibres. The foamable blends were then foam molded in a Siemag Structomat foam injection molding machine to obtain panels of the dimensions 12" x 12" x 3/8". The density of the panels were 0.85 grams/cc. Impact strength of the panels were measured by the falling dart method (ASTM D1709/62T). The panel derived from the concentrate containing the dihydrooxadiazinone blowing agent had an impact strength which averaged 90 ft.-lbs. The concentrate derived from the isopropylhydrazodi carboxylate blowing agent provided a panel having an impact strength which averaged only 60 ft.-lb.

Example 5.

A tumble-blended mixture "Blend C" of 0.6 parts of 5,6-diphenyl-3,6-dihydro1,3,4-oxadiazin-2-one and per 100 parts of a polyester resin VALOX* 310, manufactured by General Electric Company, USA, was extruded over a temperature range of between 235"C to 2540C. The intrinsic viscosity "IV" of the foamed polyester resin extrudate was measured in heptafluoroisopropenol at 250C to determine the reduction in molecular weight, if any, during the foaming process compared to the unfoamed extruded polyester as a result of polymer degradation.

The densities of these extruded samples were likewise measured. The following table shows the results obtained: TABLE IV Density (g/cc) I.V. (dl/g) T( C) Polyester Blend C Polyester Blend C 235 ---- 0.725 --- 0.870 238 1.282 0.725 0.925 0.917 243 0.723 0.930 249 1.292 0.765 0.860 0.941 254 0.758 0.945 The above results show that the dihydrooxadiazinone effects very good density reduction; more significant is the blowing agent of the present invention does not significantly lower the intrinsic viscosity of the polyester resin as a result the .foaming action indicating little or no polyester degradation.

Example 6.

A blend was prepared using 15 parts of 5,6-diphenyl-3,6-dihydro-1,3,4 oxadiazin-2-one and 85 parts of Hytrel* 4056 a polyester-polyether-copolymer which was extruded into pellets on a Brabender instrument under the following conditions: die temperature, 200 C; middle zone, 139"C; back zone, 188"C. The extruded material showed no evidence of bubbling.

The above polyester-polyether-copolymer containing 15% of the dihydrooxadiazinone is used as a blowing agent concentrate for the foaming of polyesters such as poly(butyleneterephthalate) by tumble mixing 1 part of the blowing agent concentrate per 39 parts of the polyester resin and foam molding this mixture under the following conditions: rear temperature, 243"C; center, 254"C; front 240"C; mold 93"C. A density reduction in the molded part of 35% is observed.

Example 7.

A tumble-blended mixture of 0.7 part of 5-phenyl-3,6-dihydro-l ,3A-oxadiazin-2- one per hundred parts of P--1700 polyarylsulfone manufactured by the Union Carbide Corporation was foam molded into plaques having the dimensions 3 3/8" by 3 1/88 by 3/8" on a Battenfeld BSKM 70/100B injection molding machine under the following conditions: rear temperature, 299"C; center 3020C; front, 310"C; mold, 82"C. The foamed plaque had a density of 0.51g/cc whereas an identical plaque without the blowing agent had a density of 1.27g/cc.

* Registered Trade Mark Example 8.

A tumble-blended mixture of 0.7 part of 5-phenyl-3,6-dihydro-1,3,4-oxadiazin- 2-one per 100 parts of an acrylonitrile-butadiene-styrene (ABS) copolymer was foam molded into plaques as in Example 7 under the following conditions: rear temperature, 2600 C; center 290"C; front, 2880C; mold, 380C. The foamed plaque had a density of 0.60g/cc whereas an identical plaque without a blowing agent had a density of 0.99g/cc.

Example 9 A tumble-blended mixture of 0.7 part of 5-phenyl-3,6-dihydro- 1,3,4-oxadiazin-2-one per 100 parts of a polymer alloy of polyphenylene oxide and polystyrene was foam molded into plaques as in Example 8 under the following conditions: rear temperature, 2930C; center, 2990 C; front, 3040 C; mold, 49"C. The foamed plaque had a density of 0.56g/cc whereas an identical plaque without a blowing agent had a density of 1 .07cc.

Example 10.

A tumble-blended mixture of 0.5 part of 5,6-diphenyl-3,6-dihydro-1,3,4-ox adiazin-2-one per 100 parts of a hexamethylene diamine-adipic acid polyamide resin was foam molded as in Example 7 under the following conditions; rear temperature, 2380C; center, 249"C; front, 252"C; mold, 52"C. The foamed plaque had a density of 0.53g/cc whereas an identical plaque without a blowing agent had a density of l.0lg/cc.

Example 11.

A tumble-blended mixture of 0.7 part of 5,6-diphenyl-3,6-dihydro-1,3,4-oxadiazin 2-one per 100 parts of polypropylene is foam molded as in Example 7 under the following conditions: rear temperature, 1800C; center, 2200C; front, 2300C; mold, 250C. The foamed plaques have a density in the range of 0.50.7g/cc whereas identical plaques without a blowing agent has a density of 0.95g/cc.

Example 12.

A tumble-blended mixture of 0.7 part of 5,6-diphenyl-3,6-dihydro-1,3,4-oxa- diazin-2-one per 100 parts of high impact polystyrene was foam molded as in Example 7 under the following conditions: rear temperature, 220"C; center, 2490 C front, 260"C; mold, 38"C. The foamed plaque had a density of 0.68g/cc whereas an identical plaque without a blowing agent had a density of 1.04g/cc.

Example 13.

A slurry is prepared by adding 10 parts of powdered 5-phenyl-3,6-dihydro-1,3,4-oxadiazin-2-one to a solution of 10 parts of isotactic polystyrene having a molecular weight of 200,000 and 80 parts of methylene chloride. The slurry is rapidly mixed and fed to the nozzle Polycarbonates with Chloro Bisphenols", Polymery 13, (2) 55, (1968).

A mixture of 26.25 parts of 1,1 -dichloro-2,2-bis(4-hydroxyphenyl)ethylene, .026 part of sodium gluconate, 0.237 part of phenol, 0.142 part of triethylamine, 123 parts of methylene chloride and about 75 parts of water is stirred for about 10 minutes at a temperature of about 28"C. There is then added to the mixture, an aqueous sodium hydroxide solution in an amount to adjust the pH of the aqueous phase of the mixture to approximately 10.

While the mixture is being thoroughly agitated, phosgene is introduced at a rate of about 12.24 parts per hour while a 20% aqueous sodium hydroxide solution is added in an amount sufficient to maintain the pH of the aqueous phase of the mixture at 10. Phosgenation of the mixture is continued for about 3/4 of an hour under these conditions and then the rate of phosgenation is reduced to about 6.8 parts per hour while maintaining the pH of the aqueous phase to a range of about 11 to 11.5. The phosgenation of the mixture is then continued for about 50 minutes.

The above reaction mixture is then diluted with about 100 parts of methylene chloride, and washed alternatively with a dilute hydrochloric acid, dilute sodium hydroxide and water. The mixture is then centrifuged and filtered and thereafter steam precipitated. There is obtained 26 parts of product after the precipitate is recovered and dried at 800C. Based on method of preparation, the product is 1,1dichloro-2,2-bis(4-hydroxyphenyl)ethylene polycarbonate having an intrinsic viscosity of 0.51dl/g in chloroform at 250C.

The above described dichloroethylene polycarbonate is blended with 5 phenyl-3,6-dihydro-1 ,3,4-oxadiazin-2-one and glass fiber to produce a hlend having 0.5% by weight of blowing agent and 5% by weight of glass fiber. The mixture is then melt extruded into pellets at 2600 C.

In accordance with ASTM-E-l627, 6" x 18" x 1/4" test panels are prepared by foam molding the above blend from the above described pellets at 301 C. This material has a Gardner Impact Value of about 2537.5 ft/lb and a density of about 1 .07g/cc Equivalent test panels are also prepared from a blend of the above-described dichloroethylene polycarbonate and 5% by weight of glass fiber free of blowing agent. The test panels are then used in evaluating the flame retardant properties of the glass filled dichloroethylene polycarbonate and the rigid foam derived therefrom in accordance with ASTM-E-1627. It is found that the unfoamed test panel has an I, value of';O which is equivalent to asbestos. The foamed panel is found to have an Is value of 0.8 indicating the foaming of the original dichloroethylene polycarbonate glass fiber blend does not significantly reduce the flame retardant properties of the original blend.

Example 16.

A blend is prepared of about equal parts by weight of the dichlorothylene polycarbonate of Example 15, and a Bisphenol-A polycarbonate having an instrinsic viscosity of about 0.55dVg in chloroform at 250C, along with 5% by weight of the total of glass fiber and 0.5% by weight of the blowing agent of Example 15.

The blend is melt extruded into pellets at 2600 C. Pellets are also prepared from the same blend free of blowing agent.

A 6" x 18" test panel is prepared following the procedure of Example 15 by foam molding the blend at 3 15.50C. The foamed blend has an Is value of 3.9 which is substantially equivalent to the superior flame retardant 3.7 value for the unfoamed blend. The foamed blend also has an intrinsic viscosity of about 0.45dVg in chloroform at 25"C, a Gardner Impact Value greater than 50 ft-lb and a density of about lg/cc.

Example 17.

A blend of 75 parts of the dichloroethylene polycarbonate of Example 15 and 25 parts of an ABS resin is pelletized at 2600C with 0.5% by weight of the blend of the blowing agent of Example 15 and 5% by weight of glass fiber.

Test panels are prepared by foam molding the blend at 301"C. A comparison of I, values between foamed and unfoamed 6" x 18" x 1/4" test panels in accordance with ASTM--EE-1662-67 shows a 12.0 for the unfoamed panel and a 12.5 for the foamed panel.

Example 18.

A copolymer of 11 -dichloro-2,2-bis(4-hydroxyphenyl)ethylene and 2,2-bis(4hydroxyphenyl)propane (Bisphenol-A) is prepared in accordance with the procedure of Example 15 using 13.12 parts of the dichloroethylene bisphenol and 10.65 parts of Bisphenol-A.

The above described copolymer is pelletized with 5-phenyl-3,6-dihydro-l,3,4 oxadiazin-2-one and glass fiber as in Example 15.

It is found that the I, value of the unfoamed panel is 3.8 while the foamed panel has an Is of 4.0.

As shown above in Examples 15-18 foams derived from particular compositions of the present invention, provide high Is values. Such foams are derived from the melt of thermoplastic organic blends having at least 5% by weight of chemically combined haloalkylene polycarbonate units of the formula

Where R4 and R5 are the same or different divalent aromatic radicals having from 6-13 carbon atoms, X is a halogen atom, and X1 is selected from X and hydrogen.

The thermoplastic organic blends can be reinforced with up to 60% by weight of glass fiber; the blends also can consist of haloalkylene po car ona e, blends of such haloalkylene polycarbonate with other thermoplastic polymers previously defined or a copolymer of the above haloalkylene carbonate units with other bisphenol carbonate units.

The present invention also provides a method of making a foamed shape at temperatures between 170"C to 4000C by injection molding foamable compositions as previously described, which compositions may be in the form of pellets or powder mixtures. The term thermoplastic organic polymer as previously includes polycarbonates having units

where Z is selected from the class consisting of R6 and R6QRe, where R6 is a divalent aromatic radical having from 6-13 carbon atoms and Q is selected from the class consisting of,

divalent cycloaliphatic radicals, oxyaryleneoxy radicals, sulfonyl, sufinyl, oxy, thio, fluorenyl, phenolphthalein and R7 is selected from the class consisting of C,,~,,alkyl, Re and halogenated derivatives thereof.

WHAT WE CLAIM IS: 1. An injection-moldable, foamable composition comprising a blend of a thermoplastic organic polymeric material and, based on the weight of the composition, 0.1 to 25% of a dihydrooxadiazinone having a maximum decomposition rate in the range between 170"C and 310"C, said thermoplastic organic polymeric material being capable of being molded at least twice at a temperature of 150 to 400"C.

2. A composition as claimed in Claim I containing 0.1 to 1.0% of a dihydrooxadiazinone.

3. A composition as claimed in Claim I or Claim 2 in the form of a dry powder mixture of finely divided resinous thermoplastic polymeric material and the dihydrooxadiazinone.

4. A composition as claimed in Claim 1 or Claim 2 in the form of pellets.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (20)

**WARNING** start of CLMS field may overlap end of DESC **. procedure of Example 15 using 13.12 parts of the dichloroethylene bisphenol and 10.65 parts of Bisphenol-A. The above described copolymer is pelletized with 5-phenyl-3,6-dihydro-l,3,4 oxadiazin-2-one and glass fiber as in Example 15. It is found that the I, value of the unfoamed panel is 3.8 while the foamed panel has an Is of 4.0. As shown above in Examples 15-18 foams derived from particular compositions of the present invention, provide high Is values. Such foams are derived from the melt of thermoplastic organic blends having at least 5% by weight of chemically combined haloalkylene polycarbonate units of the formula Where R4 and R5 are the same or different divalent aromatic radicals having from 6-13 carbon atoms, X is a halogen atom, and X1 is selected from X and hydrogen. The thermoplastic organic blends can be reinforced with up to 60% by weight of glass fiber; the blends also can consist of haloalkylene po car ona e, blends of such haloalkylene polycarbonate with other thermoplastic polymers previously defined or a copolymer of the above haloalkylene carbonate units with other bisphenol carbonate units. The present invention also provides a method of making a foamed shape at temperatures between 170"C to 4000C by injection molding foamable compositions as previously described, which compositions may be in the form of pellets or powder mixtures. The term thermoplastic organic polymer as previously includes polycarbonates having units where Z is selected from the class consisting of R6 and R6QRe, where R6 is a divalent aromatic radical having from 6-13 carbon atoms and Q is selected from the class consisting of, divalent cycloaliphatic radicals, oxyaryleneoxy radicals, sulfonyl, sufinyl, oxy, thio, fluorenyl, phenolphthalein and R7 is selected from the class consisting of C,,~,,alkyl, Re and halogenated derivatives thereof. WHAT WE CLAIM IS:

1. An injection-moldable, foamable composition comprising a blend of a thermoplastic organic polymeric material and, based on the weight of the composition, 0.1 to 25% of a dihydrooxadiazinone having a maximum decomposition rate in the range between 170"C and 310"C, said thermoplastic organic polymeric material being capable of being molded at least twice at a temperature of 150 to 400"C.

2. A composition as claimed in Claim I containing 0.1 to 1.0% of a dihydrooxadiazinone.

3. A composition as claimed in Claim I or Claim 2 in the form of a dry powder mixture of finely divided resinous thermoplastic polymeric material and the dihydrooxadiazinone.

4. A composition as claimed in Claim 1 or Claim 2 in the form of pellets.

5. A composition as claimed in Claim 4 in the form of pellets of the

thermoplastic polymeric material coated with the dihydrooxadiazinone.

6. A composition as claimed in Claim 1 or Claim 2 in the form of a sheet.

7. A composition in accordance with any one of the preceding claims, wherein the dihydrooxadiazinone is 5-phenyl-3, 6-dihydro-3, 6-dihydro-l, 3,4-oxadiazin-2one.

8. A composition in accordance with any one of Claims 1 to 6 wherein the dihydrooxadiazinone is 3,6-dihydro-5,6-diphenyl- 1, 3,4-oxadiazin-2-one.

9. A composition as claimed in any of of the preceding claims, wherein the thermoplastic polymeric material comprises a polycarbonate of 2,2-bis-(4-hydro phenyl)-propane.

10. A composition as claimed in any one of claims 1 to 8, wherein the thermoplastic polymeric material comprises a polyalkylene terephthalate.

I I. A composition as claimed in any one of claims 1 to 8, wherein the thermoplastic polymeric material comprises a polyphenylene-oxide based resin.

12. A composition as claimed in any one of claims 1 to 8, wherein the thermoplastic polymeric material contains at least 5% by weight of chemically combined haloethylene bisphenol carbonate units of the formula,

where R5 and Rz are the same or different divalent aromatic radicals having from 6--13 carbon atoms, X is a halogen atom and X' is selected from X and hydrogen.

13. A composition as claimed in any one of claims 1 to 8, wherein the thermoplastic polymeric material comprises a polycarbonate consisting essentially of l,l-dichloro-2,2-bis(4-hydroxyphenyl) ethylene carbonate units.

14. A composition as claimed in any one of claims 1 to 8, wherein the thermoplastic polymeric material is a copolymer consisting essentially 1,1 - dichloro-2,2-bis(4-hydroxyphenyl)ethylene carbonate units and 2,2-bis(4-hydroxyphenyl) propane carbonate units.

15. A composition as claimed in any one of the preceding claims containing glass fiber reinforcement.

16. A composition as claimed in any one of claims 1 to 8, wherein polymeric material is a blend of an acrylonitrile-butadiene-styrene terpolymer and a polycarbonate composed of the haloethylene bisphenol carbonate units as defined in claim 12.

17. A composition in accordance with any one of claims 1 to 8, wherein polymeric material is a blend of an isopropylidene-bisphenol polycarbonate and a polycarbonate composed of the haloethylene bisphenol carbonate units as defined in claim 12.

18. A method for making a shaped thermoplastic foam which comprises, (1) providing a substantially uniform mixture of a thermoplastic organic polymeric material and 0.1 to 1.0%, based on the weight of the mixture, of a dihydrooxadiazinone, the dihydrooxadiazinone having a maximum de composition rate in the range between 1700C and 310"C, said thermoplastic organic polymeric material being capable of being molded at least twice at a temperature of lsO0C to 400 C.

(2) injection molding the mixture at temperatures of 1700C to 4000C.

19. All injection mouldable foamable composition as claimed in claim I substantiily as hereinbefore described in any one of the Examples.

20. A method for making a shaDed thermoplastic foam as claimed in claim 18 substantially as hereinbefore described.

Rl. A shaped thermoplastic foam when produced by a method as claimed in claim 18 or claim 20.