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Title:
THERMOPLASTIC COMPOSITIONS CONTAINING ANHYDROUS ZINC BORATE AND A FLUOROCARBON POLYMER
Document Type and Number:
WIPO Patent Application WO/1992/000348
Kind Code:
A1
Abstract:
Thermoplastic compositions comprising at least one polyetherimide and, as heat release retardants, anhydrous zinc borate and a non-fibrillating fluorocarbon polymer are disclosed. The compositions exhibit improved heat release characteristics.

Inventors:
Kelly
William
Edward, Patel
Sanjay
Ranchhodbhai
Application Number:
PCT/US1991/004017
Publication Date:
January 09, 1992
Filing Date:
June 07, 1991
Export Citation:
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Assignee:
AMOCO CORPORATION.
International Classes:
C08K5/55; C08K3/38; C08L27/12; C08L65/00; C08L71/00; C08L71/08; C08L71/10; C08L73/00; C08L79/08; C08L87/00; (IPC1-7): C08K3/38
Foreign References:
US4777214A
US4981895A
US4639486A
EP0307670A1
Other References:
See also references of EP 0489152A1
Download PDF:
Claims:
We claim :
1. A flame resistant thermoplastic composition comprising: (a) at least one polyetherimide; (b) an effective amount for heat release improvement of anhydrous zinc borate; and (c) an effective amount for heat release improvement of a nonfibrillating fluorocarbon polymer.
2. A flame resistant thermoplastic composition comprising: (a) at least one polyetherimide; (b) at least one poly(aryl ether ketone); (c) an effective amount for heat release improvement of anhydrous zinc borate; and (d) an effective amount for heat release improvement of a nonfibrillating fluorocarbon polymer.
3. The composition of Claim 1 comprising about 1.0 to about 5.0 parts of the fluorocarbon polymer and about 2.0 to about 8.0 parts of the zinc borate, per 100 parts by weight of the polyetherimide.
4. The composition of Claim 2 wherein the fluorocarbon polymer has a molecular weight of less than about 100,000.
5. The composition of Claim 1 wherein the fluorocarbon polymer is polytetrafluoroethylene.
6. The composition of Claim 2 wherein the poly(aryl ether ketone) comprises a repeating unit of at least one of the following units : wherein Ar is independently a divalent aromatic radical selected from phenylene, biphenylene or naphthylene; X is independently 0, C=0, or a direct bond; n is an integer of 0 to 3; b, c, d, and e are 0 or 1, and preferably d is 0 when b is 1; f is an integer of 1 to 4; and in formulas (IV) and (V) at least one X is C=0. A thermoplastic composition comprising: (a) a polyetherimide having the repeating unit (b) a poly(aryl ether ketone) having the repeating unit (c) about 2.0 to about 8.0 parts by weight per 100 parts by weight of the polyetherimide and poly(aryl ether ketone) of anhydrous zinc borate; and (d) about 1.0 parts to about 5.
7. 0 parts by weight per 100 parts by weight of the polyetherimide and the poly(aryl ether ketone) of a nonfibrillating fluorocarbon polymer.
8. The composition of Claim 7 further comprising about 3.0 parts to about 12.0 parts by weight per 100 parts by weight of the polyetherimide and the poly (aryl ether ketone) of titanium dioxide.
9. The composition of Claim 7 wherein the fluorocarbon polymer comprises a polytetrafluoroethylene.
10. A thermoplastic composition having a two minute total heat release of less than about 65.0 kilowatts minute per square meter of surface area and a maximum heat release rate for the first five minutes of less than about 65.0 kilowatts per square meter of surface area, as measured by the Ohio State University heat calorimetry test described in 14 Code of Federal Regulations, Part 25Airworthiness StandardsTransport Category Airplanes, comprising at least one polyetherimide, at least one poly(aryl ether ketone), anhydrous zinc borate and a nonfibrillating fluorocarbon compound.
11. The composition of Claim 9 wherein the polyetherimide has the general formula: wherein "a" is an integer greater than 10 T is 0 or a group of the formula O—Z—0 wherein the divalent bonds of the 0 of the OZ0 group are in the 3,3; 3,4; 4,3; or the 4,4 positions, Z is a member of the class consisting of (A) and (B) divalent organic radicals of the general formula where X is a member selected from the group consisting of divalent radicals of the formulas 0 O II II — CyR2y — C S II and o where y is an integer from 1 to about 5, and R is a divalent organic radical selected from the group consisting of (a) aromatic hydrocarbon radicals having from 6 to about 20 carbon atoms and halogenated derivatives thereof, (b) alk lene radicals having from 2 to about 20 carbon atoms, cycloalkylene radicals having from 3 to about 20 carbon atoms and (c) divalent radicals of the general formula where Q is a member selected from the group consisting of CxR2x and and x is an integer from 1 to about 5.
Description:
THERMOPLASTIC COMPOS ITIONS CONTAINING ANHYDROUS ZINC BORATE AND A FLUOROCARBON POLYMER

CROSS-REFERENCE TO RFT.ΑTFD APPLICA ION This Application is a continuation-in-part application of U.S. Patent Application Serial No. 542,915, "Thermoplastic Compositions Containing Anhydrous Zinc Borate And A Fluorocarbon Polymer", filed June 22, 1990.

FIELD OF THE TNVENTTON

This invention relates generally to thermoplastic materials useful, for example, to make aircraft interior parts and, more particularly to polyetherimide thermoplastic compositions which comprise anhydrous zinc borate and a fluorocarbon polymer.

BACKGROUND OF THE INVENTION

Engineering thermoplastics are used extensively in many components of aircraft interiors, such as wall panels, overhead storage lockers, serving trays, seat backs, cabin partitions, and ducts. Engineering thermoplastics are economically fabricated into these components by extrusion, thermoforming, injection molding, and blow-molding techniques. United States Government standards for the flame resistance of construction materials used for aircraft interiors are set out in the 1986 amendments to Part 25 - Airworthiness Standards - Transport Category Airplanes of Title 14, Code of Federal Regulations (see 51 Federal Register 26206, July 21, 1986 and 51 Federal Register 28322, August 7, 1986) . The flammability standards are based on heat calorimetry tests developed at Ohio State University ("OSU TESTS") . Such Tests are described in the above-cited amendments to 14 CFR Part 25 and are incorporated herein by reference. These tests measure the two minute total heat release (in kilowatts minute per square meter of surface

area, K .min/m ) as well as the maximum heat release rate

2 (in kilowatts per square meter of surface area, K /m ) over the first five minutes for the material being tested, when burned under a specified set of conditions. The 1986 standards required engineering thermoplastics to have both of these heat release measurements under 100. The new 1990 compliance standards will allow a maximum of 65 for each of the two heat release measurements. Hence, a need exists to develop new thermoplastic compositions that have improved flammability performance, and yet display at the same time such other desirable features as toughness, chemical, solvent and cleaner resistance, and ease of fabrication into finished components.

Flame retarding additives such as triphenyl phosphate or aluminum trihydrate which generally possess low flammability have been mixed with engineering thermoplastics to reduce flammability of the thermoplastics . However, a blend of such a low flammability additive with high performance engineering thermoplastics often does not yield a useable flame-resistant composition. For example, the low flammability additive may not be compatible, i.e. miscible with the engineering thermoplastic, at high enough concentrations to achieve significant flame retardance, or the additive may not be stable at the processing temperatures of the engineering thermoplastic. Furthermore, low flammability additives which are compatible with a particular engineering thermoplastic often cannot effectively lower the flammability or heat release of the thermoplastic. If the effect on flammability is merely a reduction due to dilution, amounts of the low-flammability additive necessary to achieve a desired reduction in flammability can adversely affect the physical properties or processability of the engineering thermoplastic.

Materials consisting of a fluorocarbon polymer with either a poly(aryl ether sulfone) or a poly(aryl ether ketone) are disclosed as useful as coatings; see Vary, U.S.

Patent No. 3,992,347; Attwood, U.S. Patent No. 4,131,711; Vasta, U.S. Patent No. 4,169,117; and Saito et al., U.S. Patent No. 4,578,427. These disclosures are not directed to flame retardant thermoplastics. Mixtures of polyarylene polyethers with 0.1 to 30.0 weight percent vinylidene fluoride-hexafluoropropene copolymer were described by Barth, U.S. Patent No. 3,400,065. Several types of poly(aryl ether sulfone) are disclosed as examples of the polyarylene polyethers used in Barth's mixture. Barth does not disclose flame retardant thermoplastic compositions of zinc borate and a fluorocarbon polymer. Mixtures containing a fluorocarbon polymer, e.g., polytetrafluoroethylene, perfluorinated poly(ethylene-propylene) copolymer, or poly(vinylidene fluoride), with a number of engineering polymers including poly(aryl ether sulfones), are disclosed in European Patent Application No. 106,764. Blends of poly(aryl ether ketones) with non-crystalline copolymers of tetrafluoroethylene are disclosed in Petersen, U.S. Patent No. 4,777,214. Composite materials consisting of a mixture of poly(aryl ether sulfone), a fluorocarbon polymer, and carbon fibers or of a mixture of poly(aryl ether ketone) , a fluorocarbon polymer, and potassium titanate fibers are disclosed as useful for moldings in Japanese Patents 88/065,227B and 89/029,379B) . Rock et al., European Patent Application No. 307,670, describes mixtures of 10 weight percent of a perfluorocarbon polymer with each of a polysulfone or a polyether sulfone or a polyether ketone as having improved heat release characteristics . Rock also describes the use of the perfluorocarbon polymer, finely divided titanium dioxide or mixtures of perfluorocarbons and titanium dioxide to improve the flammability characteristics of blends of a polyetherimide with a polyetherimide-siloxane block copolymer. Rock ascribes the beneficial effect of the titanium dioxide on flame retardancy of these polyetherimide blends to interaction between the Ti0 2 and the siloxane

moiety of the block copolymer portion of the blend. Rock does not disclose flame retardant compositions comprising zinc borate and a fluorocarbon polymer.

Zinc borate or boron compounds have been used in various thermoplastic compositions. Cella, et al., U.S. 4,833,190 discloses use of hydrated zinc borate as a smoke suppressant and flame retardant in silicone containing compositions. Anderson, U.S. 4,049,619 discloses a thermoplastic composition of a polysulfone, a flame retarding bis-phenoxy compound and an enhancing agent, which is disclosed as any of numerous metal oxides and other compounds . Zinc borate is disclosed as one possible enhancing agent. Buchert, et al. , U.S. 4,981,895 discloses use of a boron containing compound as the sole flame retardant in various high temperature thermoplastics, including polyamides, polyetherimides, liquid crystal polymers, polyether sulfones, and polyether ketones. Lohmeijer, et al., EP 0,364,729 discloses use of a boron containing compound and a fluorocarbon compound as flame retardants in numerous thermoplastics. None of these references disclose flame retardant polyetherimide compositions comprising anhydrous zinc borate and a non- fibrillating fluorocarbon polymer.

It is the general object of the invention to provide thermoplastic compositions having improved heat release characteristics . It is a specific object of the invention to provide thermoplastic compositions having improved flammability performance as measured by the U.S. mandated tests for aircraft interiors. It is another specific object to provide such compositions which are readily processable in both injection molding and sheet extrusion. It is another specific object to provide such compositions having chemical and solvent resistance. Other objects will appear below. The general object of the invention can be attained by thermoplastic compositions comprising at least one

polyetherimide, anhydrous zinc borate and a non-fibrillating fluorocarbon polymer. The compositions of the invention display a combination of excellent mechanical properties, chemical resistance, and low flammability. Moreover, they are easy to melt-fabricate and yield molded articles having smooth and aesthetically pleasing surface characteristics. The instant compositions are useful in a number of applications, in particular for the construction of various panels and parts for aircraft interiors. None of the above references disclose or suggest a combination of zinc borate and a non-fibrillating fluorocarbon polymer in polyetherimide compositions.

SUMMARY OF THE INVENTION

The invention is directed to thermoplastic compositions having improved heat release characteristics comprising at least one polyetherimide, anhydrous zinc borate and a non- fibrillating fluorocarbon polymer. The compositions of the invention show an improved effect on the heat release therefrom as measured by OSU Tests. (As used herein, the flammability performance and heat release characteristics of a composition are as measured by OSU Tests.) The amount of zinc borate and fluorocarbon polymer incorporated in the compositions of the invention is an amount sufficient to reduce the heat release from the compositions, compared to the same materials without the additives. This amount is preferably about 3.0 to about 12.0 parts by combined weight of zinc borate and the fluorocarbon polymer per 100 parts by weight polyetherimide.

The compositions of the invention display improved heat release characteristics and have excellent mechanical processability. The zinc borate and the fluorocarbon polymer do not decompose at necessary processing temperatures for the composition. The compositions are also

readily melt fabricated to produce molded articles having aesthetically pleasing surfaces. The preferred compositions of the invention comprise a polyetherimide and a poly(aryl ether ketone) , and exhibit excellent solvent resistance .

DESCRIPTION OF THE REFERRED EMBODIMENTS

The invented compositions comprise at least one polyetherimide mixed with anhydrous zinc borate and a low molecular weight, non-fibrillating fluorocarbon polymer as heat release retardants. The compositions can include, in addition to the polyetherimide, other thermoplastics, such as a poly(aryl ether ketone) or a poly (phenylene ether sulfone) . Applicants have found that the use of the zinc borate and the fluorocarbon polymer in the compositions of the invention results in materials having improved heat release performance. The preferred compositions of the invention comprise:

(a) at least one polyetherimide;

(b) at least one poly(aryl ether ketone); (c) from about 3.0 to about 7.0 parts by weight, per 100 parts by weight polyetherimide, of anhydrous zinc borate;

(d) from about 1.0 to about 5.0 parts by weight, per 100 parts polyetherimide of a non-fibrillating fluorocarbon polymer having a molecular weight less than about 100,000; and

(e) from about 3.0 to about 12.0 parts by weight, per 100 parts by weight polyetherimide, of titanium dioxide.

Although compositions of the invention without Ti0 2 have excellent properties, the preferred compositions include Tiθ2 because of better heat release performance and color matching possibilities.

The Polyetherimide Component

The polyetherimides employed in the blends of this invention are well-known injection moldable engineering thermoplastics. Polyetherimides are characterized by high impact strengths, high temperature resistance and good processability.

The polyetherimides used for preparing the blends of this invention contain repeating groups of the formula

wherein "a" is an integer greater than 1, e.g., from 10 to 10,000 or more. T is -0- or a group of the formula

wherein the divalent bonds of the -0- of the -O-Z-0 group are in the 3,3; 3,4; 4,3; or the 4,4 positions. Z is a member of the class consisting of (A)

and

and (B) divalent organic radicals of the general formula

where X is a member the group consisting of divalent radicals of the formulas

0 II

—CyR 2 y —C —S —0 ,

2 . II ' _ and

where y is an integer from 1 to about 5, and R is a divalent organic radical selected from the group consisting of (a) aromatic hydrocarbon radicals having from 6 to about 20 carbon atoms and halogenated derivatives thereof, (b) alkylene radicals having from 2 to about 20 carbon atoms, cycloalkylene radicals having from 3 to about 20 carbon atoms and (c) divalent radicals of the general formula

where Q is a member selected from the group consisting of

0 0

II II -c- -s- -CxR 2 x- II and o

and x is an integer from 1 to about 5.

In one embodiment, the polyetherimide may be a copolymer which, in addition to the etherimide units described above, further contains polyimide repeating units of the formula

O O

II II c c

/ \ / \ N N N—R

\ / \ / c c II II

0 0

wherein R is as previously defined and M is selected from the group consisting of

where B is -S- or C=0.

These polyetherimide copolymers and their preparation are described by Williams et al. in U.S. Patent No. 3,983,093. The polyetherimides can be prepared by any of the methods known to those skilled in the art, including those methods described in European Patent Application No. EPO 307 670 Al, published March 22, 1989.

A preferred polyetherimide is of the general formula above wherein R is meta-phenylene and T is

and is available as ULTEM® from General Electric Company.

Mixtures of two or more polyetherimides or of a polyetherimide with other thermoplastics may be used in the compositions of the invention. For example, the polyetherimide can be mixed with a poly(aryl ether ketone) or a poly(aryl ether sulfone) . When using a mixture, the amounts of additives used in the compositions are measured on a 100 parts combined weight of the polyetherimide and other thermoplastics.

The Poly(Aryl Ether Ketone) Component

The crystalline poly(aryl ether ketones) which are suitable for the compositions of the invention contain a repeating unit of one or more of the following formulae:

wherein Ar is independently a divalent aromatic radical selected from phenylene, biphenylene or naphthylene; X is independently 0, C=0, or a direct bond; n is an integer of 0 to 3; b, c, d, and e are 0 or 1, and preferably d is 0 when b is 1; f is an integer of 1 to 4; and in formulas (IV) and (V) at least one X is C=0.

Examples of such poly(aryl ether ketones) include those h or more of the formulae:

These poly(aryl ether ketones) are prepared by any suitable method such as those well known in the art. One

such method comprises heating a substantially equimolar mixture of at least one bisphenol and at least one dihalobenzenoid compound or at least one halophenol compound as described in Canadian Patent No. 847,963. Preferred bisphenols used in such a process include: hydroquinone,

4,4 '-dihydroxybenzophenone,

4,4'-dihydroxybipheny1, and

4,4'-dihydroxydiphenyl ether. Preferred halo- and dihalobenzenoid compounds used in such a process include:

4- (4-chlorobenzoyl)phenol,

4, 4 '-difluorobenzophenone,

4,4 '-dichlorobenzophenone, 4-chloro-4 '-fluorobenzophenone,

The poly(aryl ether ketones) may also be produced by the process as described in U.S. Patent No. 4,176,222. This process comprises heating in the temperature range of 100°C to 400°C (1) a substantially equimolar mixture of (a) at least one bisphenol and (b) at least one dihalobenzenoid compound, and/or (2) at least one halophenol, in which in the dihalobenzenoid compound or halophenol the halogen atoms are activated by -CO- groups ortho or para thereto, with a mixture of sodium carbonate or bicarbonate and a second

alkali metal carbonate or bicarbonate, the alkali metal of said second alkali metal carbonate or bicarbonate having a higher atomic number than that of sodium, the amount of said second alkali metal carbonate or bicarbonate being such that there are 0.001 to 0.5 gram atoms of said alkali metal of higher atomic number per gram atom of sodium,the total amount of alkali metal carbonate or bicarbonate being such that there is at least one alkali metal atom for each phenol group present; and thereafter separating the polymer from the alkali metal halide.

Poly(aryl ether ketones) containing repeating units of t

may be produced by Friedel-Crafts reactions utilizing hydrogen fluoride- boron trifluoride catalysts as described, for example, in U.S. Patent No. 3,953,400.

Poly(aryl ether ketones) containing repeating units of the following formula:

may be prepared by Friedel-Crafts reactions using a boron fluoride-hydrogen fluoride catalyst as described in, for example, U.S. Patent Nos. 3,441,538; 3,442,857; and 3,516,966.

The poly(aryl ether ketones) may also be prepared according to the process as described in, for example, U.S. Defensive Publication T103,703 and U.S. Patent No. 4,396,755. In this process, reactants such as (a) an aromatic monocarboxylic acid, or (b) a mixture of at least one aromatic dicarboxylic acid and of an aromatic compound, or (c) combinations of (a) and (b) are reacted in the

presence of a fluoroalkane sulphonic acid, particularly trifluoromethane sulphonic acid.

Poly(aryl ether ketones) containing repeating units of the following formula:

may be prepared according to the process as described in, for example, U.S. Patent No. 4,398,020. In such a process, (a) a mixture of substantially equimolar amounts of

(i) at least one aromatic diacyl halide of the formula

Y0C-Ar 4 -C0Y

where -Ar * - is a divalent aromatic radical, Y is halogen and COY is an aromatically bound acyl halide group, wherein the diacyl halide is polymerizable with at least one aromatic compound described in (a) (ii) below, and

(ii) at least one aromatic compound of the formula

H-Ar -O-Ar » -H

where -Ar'- is a divalent aromatic radical and H is an aromatically bound hydrogen atom, which compound is polymerizable with at least one diacyl halide described in (a) (i) above, or (b) at least one aromatic monoacyl halide of formula

H-Ar"-COY

where -Ar"- is a divalent aromatic radical and H is an aromatically bound hydrogen atom, Y is halogen, and COY is an aromatically bound acyl halide group, which monoacyl halide is self-polymerizable, or (c) a combination of (a) and (b) , is reacted in the presence of a fluoroalkane sulphonic acid.

The term poly(aryl ether ketone) as used herein is meant to include homopolymers , copolymers, terpolymers, block copolymers and graft copolymers. For example, any one or more of the repeating units (I) to (V) may be combined to form copolymers, etc.

The preferred poly(aryl ether ketone) for use in the preferred compositions of the invention has repeating units of the formula:

Such a poly(aryl ether ketone) is available commercially from Imperial Chemical Industries, Ltd. under the trademark VICTREX® PEEK.

The poly(aryl ether ketones) have preferably reduced viscosities in the range of from about 0.8 to about 1.8 dl/g at measured in concentrated sulfuric acid at 25°C and at atmosperhic pressure, to provide compositions having excellent processability. For injection molding applications, Applicants prefer to use a poly(aryl ether ketone) having a melt flow above 40 g./lO minutes at 400°C, such as VICTREX®PEEK, grade 150P . For sheet applications, a poly(aryl ether ketone) having a melt flow of about 1.0 to about 8.0 g./lO minutes at 400°C, such as VICTREX® PEEK, grade 450P, is preferred.

If used, the amount of the poly(aryl ether ketone) present in compositions of the invention can be any amount,

but preferably is about 20.0 parts to about 60.0 parts by weight per 100 parts combined weight of the poly(aryl ether ketone) and polyetherimide. Blend compositions of polyetherimides with less than 20.0 parts of the (poly(aryl ether ketone) display less improved solvent resistance, which is still acceptable for some applications, and those with more than 60.0 parts of the ketone display lesser impact properties. More preferably, the poly(aryl ether ketone) amount is about 20.0 parts to about 50.0 parts, since compositions with these amounts have an excellent

_ combination of properties.

The Zinc Borate Component

The zinc borate used is anhydrous, having water amounts less than 0.2 wt.% of the zinc borate; hydrated zinc borate or zinc borates with greater water content can result in unprocessable compositions. Any suitable anhydrous zinc borate may be used. Anhydrous zinc borate of the formula 2ZnO-3B 2 0 3 having no measurable water content and a particle size of 11.8 microns is available as XPI-187 from U.S. Borax and is produced by thermal dehydration of zinc borate at 500°C. The amount of zinc borate is an effective amount to achieve low heat release, and generally is about 2.0 to about 8.0 parts by weight per 100 parts total weight of the first thermoplastic material. Amounts of zinc borate above about 8.0 parts do not provide further flammability improvement, while amounts below 2.0 parts may provide inadequate heat release retardation. In the preferred compositions of the invention, about 3.0 to about 7.0 parts zinc borate are used. Although any suitable particle size of the zinc borate can be used, zinc borate having particle size of less than about 3.0 microns ± 1.0 micron, and no particle larger than about 6.0 microns is preferred because compositions made with smaller particles have better heat release and impact performance.

The Fluorocarbon Polymer Component

The non-fibrillating fluorocarbon polymers employed in the compositions of this invention are thermoplastic fluorinated polyolefins which have an essentially crystalline structure and have a melting point in excess of about 120°C. They are preferably a polymer of one or more perfluorinated unsaturated ethylenic monomers and, optionally, one or more other unsaturated ethylenic compounds. Suitable monomers include, for example, perfluorinated monoolefins, such as hexafluoropropylene or tetrafluoroethylene, and perfluoroalkyl vinyl ethers in which the alkyl group contains up to six carbon atoms, e.g., perfluoro (methyl vinyl ether) . The monoolefin is preferably a straight or branched chain compound having a terminal double bond and containing less than six carbon atoms, and more preferably two or three carbon atoms. The fluorocarbon polymers also include those in which a portion of the fluorine atoms have been replaced by other halogen atoms, such as chlorine or bromine. Preferred fluorocarbon polymers include polytetrafluoroethylene, polychloro- trifluoroethylene, polybromotrifluoroethylene, and copolymers thereof. Other suitable fluorinated polyolefins include polyperfluorobutadiene, polyhexafluoropropylene, fluorinated ethylene propylene copolymer, and perfluoro- alkoxy resin. A particularly preferred fluorinated polyethylene is polytetrafluoroethylene (referred to hereafter as "PTFE") because it works well in the compositions of the invention and is commercially available.

Such, polytetrafluoroethylenes are fully fluorinated poly- ethylenes of the basic chemical formula (-CF 2 -CF 2 -) s which contain about 78 percent by weight fluorine.

Relatively low molecular weight fluorocarbon polymers (also referred to as non-fibrillating polymers) are used because of their performance; compositions containing higher molecular weight fluorocarbon polymers (also referred to as fibrillating polymers) may result in lesser properties,

particularly impact resistance. In general, the molecular weights of preferred fluorocarbon polymers are less than about 100,000. The optimal molecular weight may vary from one fluorocarbon polymer to another, and can be determined empirically, such as by measurement of melting point. A suitable non-fibrillating fluorocarbon polymer is a polytetrafluoroethylene, POLYMIST® F5A available from Ausimont, Morristown, New Jersey.

The fluorocarbon polymers are employed preferably in the form of finely divided solids having a particle size of less than about 5.0 microns because such solids are more easily dispersed and result in better impact properties. The fluorocarbon polymers should be highly dispersed in the thermoplastic matrix to produce low flammability products . Dispersibility is related to the molecular weight and/or particle size of the fluorocarbon polymer. The uniformity of the dispersion of the fluorocarbon polymer may be determined by observing the physical appearance of the molded product or test specimen and by measuring the degree of elongation at break of the product. Low elongation values may indicate poor dispersion.

The fluorocarbon polymer is preferably employed in amounts of about 1.0 part by weight to about 5.0 parts by weight based on 100 parts by weight first thermoplastic material. Although they can be used, concentrations of the fluorocarbon polymer above 5.0 parts by weight are undesirable since these amounts can adversely affect the moldability and can create a perlescent effect, making color matching a problem. The Optional Titanium Dioxide Component

Use of Ti0 2 provides increased ability for color matching for particular end uses, but Ti0 2 should not be used for black colored applications .

The titanium dioxide used in the instant compositions is commercially available, and any suitable Ti0 2 can be used. The particle size of the Ti0 is preferably below 5.0

microns because higher particle sizes can deleteriously affect the physical properties of the compositions. Any of the available crystalline forms of the titanium dioxide may be used, with the rutile form preferred due to its superior pigment properties.

The total amount of Ti0 2 used is preferably below about

12.0 parts by weight per 100 parts by weight of the first thermoplastic material to avoid compounding and processing difficulties. Preferred compositions employ about 3.0 to about 7.0 parts by weight zinc borate, about 1.0 to about 4.0 parts by weight fluorocarbon polymer and about 3.0 to about 7.0 parts by weight Ti0 2 , per 100 parts by weight of the first thermoplastic material.

Compounding of the Compositions

Any suitable procedure can be used to compound the compositions of the invention, and the solid components can be mixed with each other in any desired order. Applicants prefer to blend desirable amounts of the all solids present and then heat the resulting mixture to above the melting point of the highest melting polymer in the mixture. The molten mixture is then mixed for any suitable period to achieve thorough dispersion of the additive(s) and mixing of the polymers present, and then extruded and cooled into any desirable shape. Such a process can be conveniently carried out with commercial extruders such as those available from Berstorff Tire Corporation. In the compositions of the invention which comprise Ti0 2 , it is not necessary to add the oxide initially. For example, the composition containing zinc borate can be compounded first, and desirable amounts of Ti0 can be mixed in later.

Other additives may be included in the compositions of this invention. These additives include plasticizers; pigments; anti-oxidants; reinforcing agents, such as glass fibers; thermal stabilizers; ultraviolet light stabilizers; impact modifiers; mold release agents and the like.

As indicated earlier, the compositions of the present invention display excellent fabricability characteristics . They may be fabricated into any desired shape, i.e. moldings, films, fibers, and the like. They are particularly suited for the construction of various panels and parts for aircraft interiors .

EXAMPLES

The following examples illustrate the practice of this invention but they are not intended in any way to limit the scope of the invention.

The following designations are used in the examples and they have the following meaning:

PEI - ULTEM® 1000 or ULTEM® 1010, which are polyetherimide of the same general formula, but differing in melt viscosity, available commercially from General Electric Company.

PK - a poly(aryl ether ketone) of the formula

available commercially from Imperial Chemical Industries, Ltd. under the trademark VICTREX® PEEK, grade 150P, having a melt viscosit at 400 °C of 0.11 - 0.19 KNS/m 2 .

F5A - a polytetrafluoroethylene of low molecular weight (non-fibrillating) , available from Ausimont, under the trademark POLYMIST F5A®.

ZnB - anhydrous zinc borate, XPI-187 from U.S. Borax.

Experimental Procedure

All materials were prepared by first dry blending the components using a mechanical blender (turned end over end) . They were then compounded using a Berstorff ZE25, twenty- five mm co-rotating twin-screw extruder. The zone temperatures in the extruder were: Feed zone, 290-300°C; Zones 2 and 3, 340-365°C; Zones 4 and 5, 340-355°C; Zone 6, 330-355°C; and Zone 7 (Die), 335-355°C. The melt temperature ranged from 350°C to 395°C. Screw speeds were 170 to 250 rpm and head pressure ranged from 180-700 psi; varying with the materials compounded.

OSU Test specimens were made for Example 1 by compression molding of the compounded mixture in a South Bend press. Mold pressure was 500 psi for 5 minutes, then raised to 30,000 psi for the next 3 minutes, at 700°F. The mold was cooled for 10 minutes before releasing pressure. The 80 mil thick, 6x6 inch test specimens were cut from the molded material. Test specimens for Examples 2 and 3 were made by extrusion of the resins and additives in a 1" Sterling extruder. A small amount, 3 grams per 12 lbs. resin, of calcium stearate was added as a processing aid. Melt temperature was 660°F. The extruded, 60 mil thick sheet was cut into the test specimens.

O.S.U. Heat Release Tests were performed as set out in 14 CFR, Part 25, Airworthiness Standards - Transport Category Airplanes. The heat release data is an average of three tests of the sample. EXAMPLES 1-6 AND COMPARATIVE EXAMPLES 1-..

Table 1 lists test details, including sample composition and results . Example 1 used ULTEM® 1000 and Example 2 and 3 used ULTEM® 1010. Example 2 used 50 parts by weight PEI and 50 parts by weight PK per 100 parts combined weight PEI and PK, while Example 3 used 40 parts by weight PEI and 60 parts by weight PK per 100 parts combined weight PEI and PK.

Table 1

The amounts of ZnB and F5A are parts by weight per 100 parts by weight PEI or PEI/PK mixture.

In each example, use .of zinc borate and a fluorocarbon polymer showed improved heat release performance compared to the heat release of the neat polymers.

The above is not intended to be limiting. Rather, the scope of the invention is set out in the following claims.