FIRE RETARDING THERMOFORMABLE BLENDS OF COPOLYMER RESINS

Abstract: Engineering thermoplastics which are thermoformable at relatively low temperatures are prepared from blends of selected proportions of polycarbonate or polyarylate resins and polyetherimide with siloxane-polyetherimide copolymer resins. The thermoplastics of the invention exhibit flame retardancy to a degree acceptable for their use in the fabrication of aircraft components, such as interior compartment panels. Preferred blends include as a major proportion of the polycarbonate resin component, selected polyester-carbonate resins containing chain units which are residues of isophthalic and terephthalic acids.

Description: FIRE RETARDING THERMOFORMABLE BLENDS OF COPOLYMER RESINS BACKGROUND OF THE INVENTION Field of The Invention The invention relates to thermoplastic molding compositions and more particularly to thermoformable compositions which are blends of polycarbonate and polyimide resins. Brief Description of the Related Art Many applications, especially those in the transportation field, require that engineering thermoplastics be flame retardant. Polyetherimides, polycarbonates, siloxane polyetherimide copolymers, organopolysiloxane-polycarbonate copolymers and combinations thereof have been used as base resins for molding aircraft and automobile components as well as for insulation for wiring. In addition to possessing advantageous physical and chemical properties, they exhibit good flame retardant properties. See, for example, U.S. Patents 4,673,708, 4,629,759, 4,548,997, 4,468,506, 4,387,193, 4,390,665, 4,268,429 and 3,334,154. - The engineering thermoplastics that are in current use vary in their flame retardant properties, durability and thermoformability. Many do not meet the current standards for the flame resistance of construction materials used for the interior of transport category aircraft. Such standards are embodied in the 1986 amendments to Part 25 - Airworthiness Standards - Transport Category Airplanes of Title 14, U. S. Code of Federal Regulations. (See, 51 Federal Register 26206, July 21, 1986 and 51 fgcteral Register 28322, August 7, 1986). The flammability standards are based on heat calorimetry tests developed at Ohio State University. Such tests are described in the above-cited amendments to 14 C.F.R. Part 25. Other engineering thermoplastics that do meet the above- identified standards cannot be thermoformed in all circumstances, for example, in the construction of certain laminate panels, when the temperature range required for thermoforming exceeds the range for polymeric resin degradation. In the copending U.S. Patent Application S.N. 716,940, assigned to the assignee of interest in the present application and filed on June 18, 1991, ternary blends of a polyetherimide, a siloxane polyetherimide copolymer and a polycarbonate or co-polyester carbonate are described as thermoplastically moldable to fabricate articles possessing the physical and chemical resistance properties important for applications as aircraft cabin interior components, automobile parts, insulation for wiring and the like. In particular, this ternary blend results in an unexpected improvement in flame resisting performance and ductility. Further, certain ternary blends described meet or exceed the rigorous flammability standards that have been established for aircraft interior components. However, the exemplified blends (which do not include co- polyester-carbonate containing ingredients) are generally not thermoformable for lamination with films of other polymeric resins such as films of polyvinylidene fluoride (PVF) . The latter laminations require theπnoformability of the substrate at temperatures below about 200°C. to avoid damage to the PVF film. In fact, the blends described in the copending application require a minimum of 60 percent by weight of the polyetherimide component, which obviates thermoformability of this blend. Clearly, a need continues to exist for engineering thermoplastics that have improved flame retardant properties, durability and thermoformability. Thermoformable synthetic polymer compositions exhibiting a balance of ductility, solver- resistance and fire retardance are particularly in need for the aircraft industry. In certain applications, the use of PVF coated resin substrates are highly desirable. Such substrates must be capable of extrusion into sheets, coating with the PVF and thermoforming at low temperature to avoid degradation or discoloration of the PVF coating. The resin blends of the present invention have been selected to meet the above-described industry need. Further advantages found in the blends of the invention will be described more fully hereinafter. SUMMARY OF THE INVENTION The invention comprises, a thermoformable molding composition, which comprises; a blend of (a) an aromatic, thermoplastic polycarbonate resin selected from the group consisting of a polycarbonate resin and a polyarylate resin; (b) a polyetherimide resin having repeating chain units of the formula:- (I) wherein f is an integer of from about 10 to about 500; R 2 represents a divalent aliphatic hydrocarbon radical containing from 2 to about 12 carbon atoms, a divalent aromatic hydrocarbon of 6 to 30 carbon atoms, a halogenated hydrocarbon radical containing from 6 to 18 carbon atoms, or a divalent cyclo-aliphatic hydrocarbon radical containing from 3 to about 10 carbon atoms; and R 1 is a divalent aromatic organic radical having from 6 to 30 carbon atoms, inclusive; and (c) a silicone-polyetherimide copolymer containing recurring or repeating chain units of the formula (I) given above, interrupted by polysiloxane units of the formula: (ID wherein each R 5 represents a divalent hydrocarbon radical having 1 to 14 carbon atoms; each R*> is independently selected from monovalent hydrocarbon radicals having 1 to 14 carbon atoms; and d is an integer of from 4 to 40; the relative proportions (by weight) of the ingredients (a) , (b) and (c) being as represented by the shaded area of the diagram set forth in the attached drawing. In the formula (I) given above, radicals included by R 1 are aromatic hydrocarbon radicals and halogenated aromatic hydro'carbon radicals, for example, phenylene, tolylene, chlorophenylene, naphthalene, and radicals included by the formula:- -- R3 --(G)g -- R 3 -- wherein R 3 is a divalent aromatic radical having from 6-13 carbon atoms, inclusive, selected from hydrocarbon radicals and halogenated hydrocarbon radicals, g is an integer of 0 or 1; and G is a divalent radical selected from those of the formulae:- 0 0 R 4 II I! I - C Z H2 Z - , — C -, - S - , - 0 - , and — Si - ; R4 wherein z is an integer having a value of from 1-5, inclusive, and R 4 is selected from methyl and phenyl. The term "blend" as used herein means a physical mixture or alloy of the prescribed polymeric components. The compositions of the invention are useful to thermoplastically mold articles such as structural panels and the like. BRIEF DESCRIPTION OF THE DRAWING Figure 1 of the accompanying drawing illustrates a phase diagram for blends of a polyetherimide, a siloxane polyetherimide copolymer and a polycarbonate or a polyester-carbonate, wherein the relative proportions of the components are expressed as weight percentages. The shaded area of the graph represents the blends of the present invention. Figure 2 provides greater detail with a finer scale for the lower right hand portion of the diagr-am. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION Aromatic polycarbonate resins which are thermoplastically moldable are well known, as are methods of their preparation. A common method of preparation is by the interfacial polymerization technique; see for example the details provided in the U.S. Patents 3,028,365; 3,334,154; 3,275,601; 3,915,926; 3,030,331; 3,169,121; 3,027,814; and 4,188,314, all of which are incorporated herein by reference thereto. In general, the method of interfacial polymerization comprises the reaction of a dihydric phenol with a carbonyl halide (the carbonate precursor) . Although the reaction conditions of the preparative processes may vary, several of the preferred processes typically involve dissolving or dispersing the diphenol reactants in aqueous caustic, adding the resulting mixture to a suitable water immiscible solvent medium and contacting the reactants with the carbonate precursor, such as phosgene, in the presence of a suitable catalyst and under controlled pH conditions. The most commonly used water immiscible solvents include methylene chloride, 1,2- dichloroethane, chlorobenzene, toluene, and the like. The catalyst employed accelerates the rate of polymerization of the dihydric phenol reactant with the carbonate precursor. Representative catalysts include but are not limited to tertiary amines such as triethylamine, quaternary phosphonium compounds, quaternary ammonium compounds, and the li ' ;?. The preferred process for preparing polycarbonate resins used as components of the blends the invention comprises a phosgenation reaction. The temperature at which the phosgenation reaction proceeds may vary from below 0°C, to above 100°C. The phosgenation reaction preferably proceeds at temperatures of from room temperature (25°C) to 50°C. Since the reaction is exothermic, the rate of phosgene addition may be used to control the reaction temperature. The amount of phosgene required will generally depend upon the amount of the dihydric phenol and the amount of any dicarboxylic acid also present. The dihydric phenols employed are known, and the reactive groups are the two phenolic hydroxyl groups. Some of the dihydric phenols are represented by the general formula: wherein A is a divalent hydrocarbon radical containing from 1 to about 15 carbon atoms; a substituted divalent hydrocarbon radical containing from 1 to about 15 carbon atoms and substituent groups such as halogen; 0 0 II II -S- ; -S-S- ; -S- ; -S- ; -0- ; or -C- ; If II o o each X is independently selected from the group consisting of hydrogen, halogen, and a monovalent hydrocarbon radical such as an alkyl group of from 1 to about 8 carbon atoms, an aryl group of fr m 6-18 carbon atoms, an aralkyl group of from 7 to abouc 14 carbon atoms, an alkaryl group of from 7 to about 14 carbon atoms, an alkoxy group of from 1 to about 8 carbon atoms, or an aryloxy group of from 6 to 18 carbon atoms; and wherein m is zero or l and n is an integer of from 0 to 5. Typical of some of the dihydric phenols that can be employed in the practice of the present invention are bis-phenols such as (4-hydroxyphenyl)methane, 2,2- bis(4-hydroxyphenyl)propane (also known as bisphenol- A) , 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane; dihydric phenol ethers such as bis(4-hydroxyphenyl) ether, bis(3,5-dichloro-4-hydroxyphenyl) ether; dihydroxybiphenyls such as p,p' -dihydroxybiphenyl, 3,3' -dichloro- ,4' -dihydroxybiphenyl; dihydroxyaryl sulfones such as bis(4-hydroxyphenyl) sulfone, bis (3,5-dimethyl-4-hydroxyphenyl) sulfone; dihydroxybenzenes such as resorcinol and hydroquinone; halo- and alkyl-substituted dihydroxybenzenes such as l,4-dihydroxy-2,5-dichlorobenzene and l,4-dihydroxy-3- methylbenzene; and dihydroxybiphenyl sulfides and sulfoxides such as bis(4-hydroxyphenyl) sulfide, bis(4- hydroxyphenyl) sulfoxide and bis (3,5-dibromo-4- hydroxyphenyl) sulfoxide. A variety of additional dihydric phenols are available and are disclosed in U.S. Pat. Nos. 2,999,835; 3,028,365 and 3,153,008; all of which are incorporated herein by reference. It is, of course, possible to employ two or more different dihydric phenols or a combination of a dihydric phenol with glycol. The carbonate precursor can be either a carbonyl halide, a diarylcarbonate or a bishaloformate. The carbonyl halides include carbonyl bromide, carbonyl chloride, and mixtures thereof. The bishaloformates include the bishaloformates of dihydric phenols such as bischloroformates of 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis (4-hydroxy-3,5-dichlorophenyl)propane, hydroquinone, and the like, or bishaloformates of glycols such as bishaloformates of ethylene glycol, and the like. While all of the above carbonate precursors are useful, carbonyl chloride, also known as phosgene, is preferred. Also included within the scope of the present invention is the use of the high molecular weight thermoplastic randomly branched polycarbonates. These randomly branched polycarbonates are prepared by coreacting a polyfunctional organic compound with the aforedescribed dihydric phenols and carbonate precursor. The polyfunctional organic compounds useful in making the branched polycarbonates are set forth in U.S. Pat. Nos. 3,635,895 and 4,001,184 which are incorporated herein by reference. These polyfunctional compounds are generally aromatic and contain at least three functional groups which are carboxyl, carboxylic anhydrides, phenols, haloformyls or mixtures thereof. Some nonlimiting examples of these polyfunctional aromatic compounds include 1,1,1-tri (4-hydroxyphenyl) ethane, trimellitic anhydride, trimellitic acid, trimellityl trichloride, 4-chloroformyl phthalic anhydride, pyromellitic acid, pyromellitic dianhydride, mellitic acid, mellitic anhydride, trimesic acid, benzophenonetetracarboxylic acid, benzophenone- tetracarboxylic anhydride, and the like. The preferred polyfunctional aromatic compounds are 1,1,1-tri(4- hydroxyphenyl)ethane, trimellitic anhydride or trimellitic acid or their haloformyl derivatives. Also included herein are blends of a linear polycarbonate and a branched polycarbonate. The term "aromatic polycarbonate" as used herein is inclusive of copolyester-polycarbonates (also commonly referred to at times as polyester-carbonates or "PPC"), i.e., resins which contain, in addition to recurring polycarbonate chain units of the formula: (IV) wherein D is a divalent aromatic radical of the dihydric phenol employed in the polymerization reaction, repeating or recurring carboxylate units, for example of the formula: 0 0 (_ C - R 7 - C - 0 - D - 0 -)- wherein D is as defined above and R 7 is an aromatic radical such as phenylene, naphthylene, bisphenylene, substituted phenylene and the like. The copolyester-polycarbonate resins are also prepared by interfacial polymerization technique, well known to those skilled in the art; see for example the U.S. patents 3,169,121 and 4,487,896 which are incorporated herein by reference thereto. In general the copolyester-polycarbonate resins are prepared as described, above for the preparation of polycarbonate homopolymers, but by the added presence of a dicarboxylic acid (ester precursor) in the water immiscible solvent. Preferred polycarbonates employed in the present invention are polyester-carbonate (PPC) resins containing recurring polycarbonate chain units of the formula (IV) given above and repeating or recurring carboxylic chain units of the formula:-- (V) wherein D has the meaning previously ascribed to it and R 8 is a divalent moiety selected from those of the formulae: or These preferred polyester-carbonate resins are prepared employing as the ester precursor an aromatic dicarboxylic acid, and in particular mixtures of terephthalic acid with isophthalic acid wherein the weight percentage of isophthalic acid to terephthalic acid is in the range of from about 100:0 to about 0:100. Preferably the weight percentage - within the range of from about 25:75 to 75:25. Rather than utilizing the dicarboxylic acid per se, it is possible, and sometimes even preferred, to employ the reactive derivatives of said acid. Illustrative of these reactive derivatives are the acid halides. The preferred acid halides are the acid dichlorides and the acid dibromides. Thus, for example instead of using terephthalic acid or mixtures thereof with isophthalic acid, it is possible to employ terephthaloyl dichloride, and mixtures thereof with isophthaloyl dichloride. In the conventional interfacial polymerization methods of preparing polycarbonates polyester-carbonate and polyarylates, a molecular weight regulator (a chain stopper) is generally added to the reaction mixture prior to or during the contacting with a carbonate and/or ester precursors. Useful molecular weight regulators include, but are not limited to, monohydric phenols such as phenol, chroman-I, paratertiarybutylphenol, p- cumylphenol and the like. Techniques for the control of molecular weight are well known in the art and ' are used for controlling the molecular weight of the resins used in blends of the present invention. The proportions of reactants employed to prepare the most preferred polyester-carbonate resins may vary within a limited range. In general, the weight percentage content of the ester units of the formulae VI and VII together may be from about 40 .- z about 80 percent. The preferred polyester-carbonates for use in the present invention are those derived from bisphenol-A and phosgene and having an intrinsic viscosity of about 0.5 to about 0.65 deciliters per gram measured in methylene chloride at a temperature of 25°C. Polyarylates are well known resins consisting of repeating carboxylic chain units as shown in the formula (V) given above. The polyarylate polymers, in general, are prepared by reacting an aromatic difunctional carboxylic acid or ester forming derivative thereof, and a dihydric phenol. Of course, polyarylates may be polymerized from a carboxylic acid/hydroxy functional monomer in a head-tail arrangement. The aromatic dicarboxylic acids and dihydric phenols described above for preparation of polyester-carbonates may be used in the preparation of polyarylate resins. In a preferred polyarylate the difunctional carboxylic acid residue portion contains residues of mixtures of terephthalic acid and isophthalic acid. More preferably, such polyarylates contain residues of a mixture of from about 30 to about 70 mole percent terephthalic acid and from about 70 to about 30 mole percent of isophthalic acid. A polyarylate containing residues of a mixture of 50 mole percent of terephthalic acid and 50 mole percent isophthalic acid is common. In general, these and other suitable polyarylates have a reduced viscosity of from about 0.4 to about 1.0 g/100 ml as measured in p-chlorophenol at 49°C. The polyarylates employed in the present invention can be prepared by any of the well known prior art polyester forming reactions, such as the reaction of the acid chlorides of the aromatic dicarboxylic acids with the dihydric phenol, the reaction of the diaryl esters of the aromatic dicarboxylic acids with the dihydric phenols, and the reaction of the aromatic diacids with diester derivatives of dihydric phenol. These processes are described in, for example, U.S.- Pat. Nos. 3,317,464; 3,948,856; 3,780,148; 3,824,213; 3,133,898; and 4,477,647; all of which are incorporated herein by reference thereto. The polyimide resins comprising the ingredient (b) in the blends of the invention are also known compounds whose preparation and properties are well known to those skilled in the art. For the purposes of the instant invention the polyetherimides are the preferred polyimides. The preferred polyetherimides are described in U.S. Patent Nos. 3,803,085 and 3,905,942, both of which are incorporated herein by reference. These polyetherimides are represented by the general formula (I) given above. Illustrative of a particularly preferred polyetherimide falling within the scope of Formula (I) is one wherein R 2 is phenylene and R 1 is the divalent moiety of formula:- (VIII) In general,- the polyetherimides of formula (I) given above may be prepared by the reaction of an aromatic bis (ether anhydride) of the formula: - (IX) wherein R 1 is as defined above, with an organic diamine of the formula: H 2 N—R 2 — H 2 (X) where R 2 is as defined hereinbefore. Aromatic bis (ether anhydride) s of the above formula (IX) include, for example, 2,2-bis [4- (2,3- dicarboxyphenoxy)phenyl]propane dianhydride; 4,4'- bis (2, 3-dicarboxyphenoxy) diphenyl ether dian-hydride; 1, 3-bis (2, 3-dicarboxyphenoxy)benzene dianhydride; 4,4'- bis (2 , 3-dicarboxyphenoxy) diphenyl sulfide dianhydride; 1,4-bis (2, 3-dicarboxy-phenoxy)benzene dianhydride; ,4' -bis (2, 3-dicarboxyphenoxy) benzophenone dianhydride; 4,4' -bis (2,3-dicarboxyphenoxy)diphenyl sulfone dianhydride; 2,2-bis [4- (3,4-dicarboxyphenoxy) -phenyl] - propane dianhydride; 4,4 ' -bis (3,4- dicarboxyphenoxy)diphenyl ether dianhydride; 4,4'- bis(3,4-dicarboxyphenoxy) - diphenyl sulfide dianhydride; 1,3-bis (3,4-dicarboxyphenoxy)benzene dianhydride; 1,4-bis (3,4-dicarboxyphenoxy)benzene dianhydride; 4,4 ' -bis (3,4-dicarboxyphenoxy) - benzophenone dianhydride; 4- (2,3-dicarboxyphenoxy) -4 ' - (3,4 dicarboxy- phenoxy) iphenyl-2,2-propane dianhydride; and mixtures of such dianhydrides. Organic diamines of the formula (X) include, for example, m-phenylenediamine, p-phenylene-diamine, 4,4'- diaminodiphenyl propane, 4,4' -diaminodiphenyl methane, benzidine, 4,4 ' -diaminodiphenyl sulfide, 4,4'- diaminodiphenyl sulfone, 4,4 ' -diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3 ' -dimethyl- benzidine, 3,3'- dimethoxybenzidine, 2,4-bis (β-amino-t-butyl) toluene, bis(p-β-amino-t-butyl- phenyl)ether, bis (p-β-methyl-o- aminophenyl)benzene, 1,3-diamino-4-isopropylbenzene, 1,2-bis(3-amino-propoxy)ethane, m-xylylenediamine, p- xylylene-diamine, 2,4-diamino- toluene, 2,6-diamino- toluene, bis(4-aminocyclo- hexyl)methane, 3,methylheptamethylenediamine, 4,4-dimethyl- heptamethylenediamine, 2,11-dodecanediamine, 2,2- dimethylpropylenediamine, octamethylenediamine, 3- methoxyhexamethylene- diamine, 2,5-dimethylhexa- methylenediamine, 2,5-dimethylheptamethylene-diamine, 3-methyl- heptamethylenediamine, 5-me hylnonamethyl- enediamine, 1,4-cyclohexane-diamine, 1,12- octadecanediamine, bis(3-amino-propyl) sulfide, N- methyl-bis(3-aminopropyl)amine, hexamethylene- diamine, heptamethylenediamine, nonamethylene- diamine, decamethylenediamine, bis (3-aminopropyl) tetramethyldisiloxane, bis (4- aminobutyl)tetramethyldisiloxane, and the like. In general, the reactions can be advantage-ously carried out employing well-known solvents, e.g., o- dichlorobenzene, m-cresol/toluene and the like to effect interaction between the dianhydride.-; and the diamines, at temperatures of from about 100° to about 250°C. Alternatively, the polyether- imides can be prepared by melt polymerization of any of the aforementioned dianhydrides with any of the aforementioned diamine compounds while heating the mixture of the ingredients at elevated temper-atures with concurrent intermixing.. Generally, melt polymerization temperatures between about 200° to 400°C. and preferably 230° to 300°C can be employed. Any order of addition of chain stoppers (molecular weight regulators) ordinarily employed in melt polymerization can be used. The conditions of the reaction and the pro¬ portions of ingredients can be varied widely depending on the desired molecular weight, intrinsic viscosity, and solvent resistance. In general, equimolar amounts of diamine and dian-hydride are employed for high molecular weight polyetherimides. However, in certain instances, a slight molar excess (about 1 to 5 mol percent) of diamine can be employed resulting in the production of polyetherimides having terminal amine groups. Generally, useful polyetherimides have an intrinsic viscosity [_] greater than 0.2 deciliters per gram, preferably 0.35 to 0.60, or 0.7 deciliters per gram or even higher when measured in m-cresol at 25°C. Included among the many methods of making the polyetherimides are those disclosed in U.S. Patent Nos. 3,847,867; 3,847,869; 3,850,885; 3,852,242; and 3,855,178. These disclosures are incorporated herein in their entirety by reference for the pur-pose of teaching, by way of illustration, general and specific methods for preparing polyetherimides for αse in the blends of this invention. The silicone-polyetherimide employed in the preferred blends of the invention as the ingredient (c) are exemplified by resins containing recurring or repeating chain units of the formula (I) given above interrupted by polysiloxane units of the formula (II) given above. The silicone-polyetherimide resins described above are generally well-known compounds, which may be prepared by a number of known methods; see for example the procedures described in U.S. Patents 4,690,997 and 4,808,686 incorporated herein by reference thereto. In general, the method of preparation may be by reaction between amino-terminated polydiorgan siloxanes of the formula: NH 2 — R 5 —(- wherein R 5 , R 6 and d have the meanings previously ascribed to them; and an organic diamine of the formula (X) given above; with a substantially equal molar proportion of an aromatic bisanhydride of the formula (IX) given above. The amine-terminated polydiorganosiloxanes (XI) are also well-known compounds which may be prepared by the procedures described in the U.S. Patent 3,185,719 (Prober) which is hereby incorporated herein by reference thereto. The preferred silicone-polyetherimide resins for use in the present invention contain about 20 to 60 weight percent of siloxane units of the formula (II) given above. The relative proportions of the polymer blend ingredients (a) , (b) and (c) described above are within a particular defined range, as illustrated in the accompanying drawing. The blends of the invention are represented substantially by the shaded area of the phase diagram shown in the drawing. This shaded area corresponds approx-imately to blends containing from about 63 to about 89 parts by weight of aromatic polycarbonate or polyarylate (a), about 0.4 to about 4.6 parts of the silicone-polyetherimide copolymer (c) and the balance of polyetherimide resin (b) . The concentration of the polyetherimide resin (b) in the blends of the invention is at least 8.5 percent by weight of the three ingredients, and not more than about 35 percent by weight. The blend compositions of the invention may be modified by the addition of other additives conven¬ tionally used in the art of plastics compounding. Such additives can include fillers (such as clay or talc) , supplementary delustrants, reinforcing agents (such as glass fibers) , impact modifiers, antistats, plasticizers, flow promoters and other processing aids, stabilizers, colorants, mold release agents, ultraviolet screening agents, drip inhibitors such as polytetrafluoroethylene (PTFE) , supplementary or synergistic flame retardants, and the like provided the addition does not adversely affect desired properties in the articles molded from the blend. Additional preferred embodiments of the invention include thermoplastic molding compositions containing mixtures of the above-described polyester-carbonates or polyarylates with minor proportions (less than about 40 percent by weight) of polycarbonate homopolymers. Preferred blend compositions of the invention include a flame retarding proportion of a flame retarding additive compatible with the blend of the invention. Particularly preferred as a flame retarding additive is sodium benzenephosphinate (SBP) or sodium 2,4, 5-trichlorobenzene-sulfonate (STB) . The flame retarding proportion of these two particularly preferred fire retarding agents is generally within the range of from about 50 to about 500 PPM of the polyetherimide resin (b) ingredient. Preferred compositions of the invention may also include a fire retardant enhancing proportion of titanium dioxide (generally within the range of from about 0.1 to 3 parts by weight) . The production of the blend compositions of the invention is done by any of the blending operations known for the blending of thermo-plastics, for example blending in a kneading machine such as a Banbury mixer or an extruder. The sequence of addition (except in respect to inclusion of the flame retardants STB and SBP to be described hereinafter) is not critical but all components should be thoroughly blended together. Blending, including melt blending, can be done continuously or batchwise. The invention will be better understood with reference to the following preparations and examples, which are presented for purposes of illustration rather than for limitation, and which set forth the best mode contemplated for carrying out the invention. The term "iso/tere" is used herein to mean the ratio by weight of isophthalic moieties of the formula (VI) to terephthalic moieties of formula (VII) given above. Where reported, the following test * procedures were followed: Heat and Smoke Release Determined by the Ohio State University (OSU) rate-of-release apparatus and the U.S. National Bureau of Standards (USNBS) Smoke Chamber, which are in accordance with the procedures set forth in Part 25 of Title 14, U.S. Code of Federal Regulations as amended (51 Federal Register 26206 and 28322) . The tests measure rates of heat release at the peak of release and at 2 minutes after ignition. To be acceptable under the test standard, the 2 minutes heat release value must be below 65 kilowatts x minutes M 2 and the peak heat release rate must be below 65 kilowatts M< Solvent Resistance The chemical resistance testing was performed as follows : Strain jigs were obtained with a 7.08 in. radius (0.875% strain) . Izod bars (2.5 in. x 0.5 in. x 125 in.) were clamped in the strain jig. The samples were then soaked as follows with the appropriate solvents at the times indicated below: A two ply paper towel saturated (but not dripping) with the desired solvent was placed on the middle of the bar for 60 seconds. The paper towel was then removed. At the appropriate times the specimens were checked visually for cracks, crazing or dissolution of the resin. The samples were soaked and observed according to the following schedule (hours) : 0 (soak/observe) , 0.5 observe, 1.0 (soak/observe), 1.5 (observe) , 2.0 (soak/observe) , 2.5 (observe), 3.0 (soak/observe) , 4.0 (soak/observe), 24.0 (observe) . The results at the end of 24 hours are listed in Table VIII. Notched Izod (NI) Impact on molded samples was determined according to ASTM test method D-256. Molecular Weight (M.^) The weight average molecular weight (M w ) is determined by gel permeation chromatography (GPC) in methylene chloride relative to polycarbonate standards using a UV detector at 254 nm. WEIGHT PERCENT ESTER CONTENT IN PPC RESINS Weight percent ester content is calculated in the following manner wherein the dihydric phenol reactant is bisphenol A. Wt. % ester = (mole % ester) (358) xlOO (mole ester) (358) + (mole % carbonate) (254) Mole % ester = moles of aromatic diacid x 100 • moles of dihydric phenol 358 = molecular weight of the unit and 254 = molecular weight of the unit All parts are by weight unless otherwise stated. Examples 1-11 In a series of runs, various proportions (parts by weight) of a bisphenol-A derived polyester-carbonate (PPC) resin characterized by having an 80 percent by weight content of ester units of the formulae (VI) and (VII) given above and an iso/tere weight ratio [units of formula (VI) : (VII)] of 93/7, were blended with varying parts by weight of an antioxidant (Irgafos ® 168; Ciba-Geigy Corp.) , a polyetherimide resin containing about 350 ppm of the fire-retardant compound sodium benzenephospinate (Ultem ® 1000 grade, General Electric Company, Pittsfield, Massachusetts) and a siloxane- polyetherimide copolymer prepared by the polymerization of 1 equivalent of 2,2-bis [4- (3,4-dicarboxy-phenoxy) phenyl] propane dianhydride with 0.65 equivalents of meta-phenylenediamine and 0.35 equivalents of bis- gamma-aminopropyl polydimethyl siloxane, a polymer of the formula (II) given above wherein d is an average of 10; Siltem ® , General Electric Co., Pittsfield, MA., U.S.A. Example 1 contains no Siltem ® and is given as a control . The blend was then fed to an extruder at a temperature of about 340°C. to extrude the blend into strands. The strands were chopped into pellets and injection molded into test samples measuring 6.35 cm X 1.27 cm X 0.317 cm. The samples were tested for physical properties. The composition of each blend and the test results are set forth in the Table, I. below. TABLE I cnz CO h l-π m =0 en 00 ~n. As can be observe from the Table I, blends of the invention meet the specification of the OSU flame retarding test and are thermoformable. Example 1, which is not an example of the invention, does not meet the OSU specification for flame retarding. Examples 12-19 The general procedure of Examples l-ll, supra. , was repeated, except that the polyester-carbonate (PPC) as used therein was replaced with a polyester-carbonate having a 60% by weight content of the ester units of formulae (VI) and (VII) in an iso/tere weight ratio of 50/50 and varying proportions of titanium oxide were added to the blend. The composition of each blend and the physical test results are set forth in the Table II below. TABLE II EXAMPLES : 12 13 14 15 16 17 18 19 Blend Formulation (parts by wgt.) PPC 92.10 75.80 73.90 63.20 73.9 66.7 73.9 85.6 O Siltem* 2.80 1.20 2.50 2.00 2.5 1.3 2.5 3.4 CD Ultem* 2.50 20.80 21.50 33.00 21.5 30 21.5 8.6 Tio 2 2.50 2.10 2.00 1.70 2.00 1.90 2.00 2.30 Irgafos* 168 0.10 0.10 0.10 0.10 0.10 0.10 0.10 0.10 00 CΛ Physical Properties: Notched Izod (kg/cm 2 ) 125 mil 0.63 0.39 0.41 0.15 0.28 0.19 0.40 0.61 Fire Retardance IV) OSU 2 MIN. (2kw/m 2 ) 41 12 21 26 13 11 15 13 PEAK (kw/m 2 ) 49 54 56 62 51 52 59 61 NBS Ds Max 26 19 17 22 16 22 Examples 20-22 The general procedure of Examples 1-19, supra. , was repeated, except that the polyester-carbonate (PPC) as used therein was replaced with a polyester-carbonate having varying ester unit contents of 40 to 80 percent by weight of the units of the formulae (VI) and (VII) and varying iso/tere weight ratios. The proportions of blend ingredients are as given below, TABLE III Parts by Wcrt . PPC 74.0 Ultem ® , supra. 21.5 Siltem ® , supra. 2.4 Ti0 2 2.0 Irgafos ® , 168, supra. 0.1 The PPC resin used and the physical properties observed upon testing are set forth in the Table IV below. TABLE IV Table IV shows that the besl OSU (peak heat release rates) results are obtained with PPCs containing 80% ester. Notice, however, the ductility of the blend is strongly influenced by the ratio of iso- to terephthalate groups making up the ester in the PPC. thus, the most preferred PPC containing blend compositions contain 60 to 80% by weight ester and an iso/tere ratio of 25/75 to 75/25. The blends of the invention shown in the Examples given above have softening points within temperature ranges below about 200°C. As such, these blends are extrudable in sheet configurations which can be laminated with layers, for example, of polyvinylidene fluoride (a decorative laminate) . The laminate may then be thermoformed, using conventional techniques, into aircraft interior components such as wall panels, without melting or discoloring the polyvinylidene fluoride layer. Examples 23-28 A series of blends were prepared by mixing 74 parts by weight of a polyester-carbonate resin containing 80 percent by weight of the ester moieties of formula (VI) and (VII) in an iso/tere weight ratio of 93/7, or 60 percent by weight of the .ester moieties of formula (VI) and (VII) in an iso/tere weight ratio of 50/50, with 2.4 parts by weight of the siloxane-polyetherimide copolymer resin Siltem ® , supra., 2.0 parts by weight of titanium dioxide, 0.1 parts by weight of the antioxidant Irgafos ® 168, supra., and 21.5 parts by weight of a polyetherimide (Ultem ® , supra.). Various proportions of sodium benzenephosphinate were also added to the blend through inclusion iri the Ultem ® resin, either during the polymerization process or post polymerization. The blend compositions and OSU test results are given in the Table V below. TABLE V Effect Of the Addition Of SBP to Blend EXAMPLES : 23 24 25 26 27 28 Blend Formulation: (parts by weight) CO cz PPC (a) 74.00 0.00 0.00 0.00 0.00 0.00 σα CO PPC (b) 0.00 74.00 74.00 74.00 74.00 74.00 SBP in Ultem* Resin 0.00 350(d.) 350(d.) 350 (d.) 0.00 500 (C) Ul Fire Retardance O rπ OSU 2 MIN. (2kw/m 2 ) 25.00 12.00 12.00 5.00 6.00 13.00 3D Peak (kw/m 2 ) 57.00 50.00 50.00 44.00 58.00 54.00 m a. PPC = 93/7 iso/tere ratio, 80 wgt. % ester b. PPC = 50/50 iso/tere ratio, 60 wgt. % ester c. Added to ULTEM Resin Via Extrusion (concentration of SBP given in ppm relative to ULTEM*) . d. Added to ULTEM During Polymerization Process (concentration of SBP given in ppm relative to ULTEM*). Examples 29-32 The general procedure of Examples 23-28, supra. , was repeated, except that the polyester-carbonate resin as used therein was replaced with a polyester-carbonate resin containing 60 weight percent of the ester unit moieties of formulae (VI) and (VII) in an iso/tere weight ratio of 50/50 and the fire retardant additive was replaced with sodium 2,4,5- trichlorobenzenesulfonate. The test results are also shown in Table VI, below. TABLE VI Examples 29 30 31 32 Blend Formulation CO PPC (a) 74.00 73.92 73.70 73.41 CD C Siltem*, supra. 2.40 2.40 2.39 2.38 Ti0 2 2.00 2.00 2.00 1.98 Irgafos*, 168 0.10 0.10 0.10 0.10 m Ultem •, supra. 21.50 21.48 21.41 21.33 CO STB (c) 0.00 0.10 0.40 0.80 Fire Retardance 33 OSU 2 Min. (2 Kw/m 2 ) 17.00 15.00 21.00 26.00 r Peak (Kw/m 2 ) 63.00 56.00 61.00 61.00 (a) PPC = 50/50 Iso/Tere Ratio, 60 wt % Ester (c) STB = sodium 2,4,5-trichlorobenzenesulfonate From the Table V it is observed that low levels of sodium benzenephosphinate (SBP) added to the polyetherimide resin, improves the OSU performance of the blend. Example 28 shows that when SBP (500 ppm in Ultem ® ) is compounded into the Ultem ® prior to the addition of the PPC, a significant increase in the OSU performance was noted over Example 27. Note that sodium 2, 4, 5-trichlorobenzenesulfonate (STB) shows similar behavior (Table VI) , Example 30 compared to Example 39. Examples 33-46 A series of blends were prepared following the general procedure of Examples 1-19, supra., but various proportions of the polyester-carbonate used therein were replaced with a polycarbonate homopolymer and/or a polyarylate. The blend compositions and the test results are set forth in the Table VII. below. TABLE VI I CO c CD CO z m —I O (a) PPC = 93:7 Iso/Tere Ratio, 60 wt % Ester (b) A polycarbonate homopolymer prepared by phosgenation of bisphenol-A, M w of 36,300; General Electric Co., Mt. Vernon, Indiana. (c) Polyarylate (100% ester, iso/tere weight ratio = 50/50) . The product of reacting bisphenol-A with terephthalic and isophthalic acids, M w 25,500; Amoco Chemical Corp., Chicago, Illinois. Polycarbonate, polyestercarbonate and polyarylates form miscible blends. Table VII indicates that polycarbonates, polyester-carbonates and/or polyarylates can be blended together for use in these blends. The performance of the blend is related to the average ester content and average iso/tere content in the poly(estercarbonate) phase. Those skilled in the art will appreciate that the blends of the invention preferably include polymer chain moieties of the formulae (VI) and ( T"" I) together comprising from 40 to 80 weight percent (preferably 60 to 80 weight percent) of the polyester-carbonate or 100 percent of the polyarylate, the weight ratio of units of the formula (VI) to units of the formula (VII)- being within the range of 7:93 to 75/25, preferably 25:75 to 75:25. The Example 37 given above illustrates that even without ingredients having the units of formulae VI and VII, the blends are marginally fire retardant and useful for some application. Example 38 A series of blends were prepared by homogeneous mixture of various polyester-carbonate resins (74.0 parts by weight) with 21.5 parts by weight of the polyetherimide resin (Ulten ® , supra.) 2.4 parts by weight of the siloxanepolyetherimide copolymer resin (Siltem ® , supra.) and 2.0 parts by weight of titanium dioxide. The blends were thermally processed as described in Examples 1-19, supra, and the test samples obtained were tested for solvent resistance in a variety of industrial solvents . the polyester- carbonates employed, the solvents tested against and the results are given in the Table VIII, below. TABLE VTTT 80% By Weight Ester Units 40% By Weight Ester Units Iso/Tere Ratio 93/7 50/50 93/7 50/50 o/ioo Solvents Toluene (neat) crazed failed passed passed crazed 50/50 (a) crazed failed failed crazed failed Methylethylketone (MEK) (neat) failed failed 50/50 (b) passed passed passed | passed passed Trichloro- ethylene (TCE) ^ 50/50 (c) passed passed passed passed passed a. Toluene/isopropanol 50/50 (v/v). b. MEK/isopropanol 50/50 (v/v) c. TCE/isopropanol 50/50 (v/v)

Claims: WHAT 15 CLAIMED IS: 1. A thermoformable molding composition, which comprises; a blend of (a) an aromatic, thermoplastic resin selected from the group consisting of a polycarbonate resin and a polyarylate resin; (b) a polyetherimide resin having repeating chain units of the formula:- (I) wherein f is an integer of from about 10 to about 500; R 2 represents a divalent aliphatic hydrocarbon radical containing from 2 to about 12 carbon atoms, a divalent aromatic hydrocarbon of 6 to 30 carbon atoms, a halogenated hydrocarbon radical containing from 6 to 18 carbon atoms, or a divalent cyclo-aliphatic hydrocarbon radical containing from 3 to about 10 carbon atoms; and R 1 is a divalent aromatic organic radical having from 6 to 30 carbon atoms; and (c) a silicone-polyetherimide copolymer containing recurring or repeating chain units of the formula (I) given above, interrupted by polysiloxane units of the formula:- (II) wherein each R^ represents a divalent hydrocarbon radical having 1 to 14 carbon atoms; each R^ is independently selected from monovalent hydrocarbon radicals having 1 to 14 carbon atoms; and d is an integer of from 4 to 40; the relative proportions by weight of the ingredients (a) , (b) and (c) being as represented by the shaded area of the diagram set forth in the attached drawing. 2. The composition of claim 1 wherein R 1 is selected from the group consisting of a ' romatic hydrocarbon radicals; halogenated aromatic hydrocarbon radicals; and radicals included by the formula:- R3 (G)g _ R 3 wherein R 3 is a divalent aromatic radical having from 6-13 carbon atoms selected from hydrocarbon radicals and halogenated hydrocarbon radicals, g is 0 or l and G is a divalent radical selected from those of the formula:- wherein z is an integer having a value of from 1-5, and R 4 is a monovalent alkyl, aryl, alkaryl or aralkyl radical. 3. The composition of claim 2 wherein R 1 is a 4. The composition of claim 3 wherei. ' . the aromatic polyester-carbonate is a copolymer resulting from the condensation of bisphenol A with a mixture of terephthaloyl dichloride with isophthaloyl dichloride; and phosgene. 5. The composition of claim 1 wherein the aromatic resin selected is a polycarbonate. 6. The composition of claim 1 wherein the aromatic resin selected is a polyarylate. 7. The composition of claim 1 which further comprises a flame retarding proportion of a flame retardant additive. 8. The composition of claim 7 wherein the additive is sodium benzenephosphinate. 9. The composition of claim 7 wherein the additive is sodium 2,4,5-trichlorobenzenesulfonate. 10. The composition of claim 7 wherein the additive is pre-mixed with the polyetherimide (b) before blending with the remaining ingredients (a) and (c) . 11. The composition of claim 10 wherein the fire retarding proportion is within the range of from about 50 to 500 PPM of the polyetherimide. 12. The composition of claim 1 which further comprises a proportion of titanium dioxide. 13. The composition of claim 11 wherein the proportion of titanium dioxide is within the range of from about 0.1 to 3 parts by weight. 14. The composition of claim 1 wherein the resin (a) selected is a polyester-carbonate res. i containing recurring polycarbonate chain units of the formula: - wherein D is a divalent aromatic radical of the dihydric phenol employed in the resin preparation; and repeating or recurring carboxylic chain units of the formula: - — 0— R— O— D — wherein D has the meaning previously ascribed to it and R is a divalent moiety selected from those of the formulae: - (VI) or said composition having an average of about 40 to 80 weight percent of ester units of the formulae VI and VII together; and said moieties (VI) and (VII) in the blend being in a weight ratio within the range of from about 100:0 to about 0:100. 15. The composition of claim 14 wherein said ratio is within the range of from about 25:75 to 75:25. 16. The composition of claim 14 wherein the aromatic polyester-carbonate is a copolymer resulting from the condensation of bisphenol A with terephthaloyl dichloride and phosgene. 17. The composition of claim 14 which further comprises an effective amount for fire retardation of a fire retardant. 18. The composition of claim 17 wherein the fire retardant is selected from the group consisting of sodium benzenephosphinate and sodium 2, 4, 5- trichlorobenzene-sulfonate. 19. The composition of claim 14 which further comprises a minor proportion of an aromatic polycarbonate homopolymer. 20. An article thermoplastically molded from the composition of claim 14. 21. The article of claim 20 which is laminated to a film of PVF and thermoformed. 22. The composition of claim 1 wherein the resin (a) selected is a thermoplastic aromatic polyarylate resin having repeating chain units of the formula:- —0 R— O D wherein D is a divalent aromatic radical of the dihydric phenol employed in the resin preparation; and R is a divalent moiety selected from those of the formulae: or said moieties (VI) and (VII) in the blend being in a weight ratio within the range of from about 50:50. 23. The composition of claim 22 wherein there is also present a minor proportion by weight of a polycarbonate homopolymer resin. 24. The composition of claim 22 which further comprises an effective amount for fire retardation of a fire retardant. 25. The composition of claim 24 wherein the fire retardant is selected from the group consisting of sodium benzenephosphinate and sodium 2,4,5- trichlorobenzenesulfonate. 26. The composition of claim 24 which further comprises a fire retardant enhancing proportion of titanium dioxide. 27. The composition of claim 26 wherein the proportion of titanium dioxide is within the range of from about 0.1 to 3 parts by weight. 28. An article thermoplastically molded from the composition of claim 22.

Inventors: GLASER RAYMOND HANS, SYBERT PAUL DEAN, GLASER, RAYMOND, HANS, SYBERT, PAUL, DEAN
Applicants: GEN ELECTRIC, GENERAL ELECTRIC COMPANY
Application year: 1993
Main classification: C08L79
IPC codes: C08J5, C08K3, C08K5, C08L67, C08L69, C08L79