DE2756435A1 - FIRE RESISTANT THERMOPLASTIC POLYESTER COMPOUNDS - Google Patents

Description

PATENT ADVOCATE DR. HANS-GUNTHER EGGERT ₁ DIPLo2iiÄfe4iÄ5BR

5 COLOGNE 51, OBERLANDER UFER 90

S-

Cologne, December 16, 1977 No. 153

General Electric Company, 1 River Road, Schenectady 5, New York (USA)

Fire retardant thermoplastic polyester compounds

The present invention relates to fire retardant thermoplastic polyester compositions with improved melt strength, and in particular thermoplastic compositions with a branched polyalkylene terephthalate having a high molecular weight and a fire retardant.

Linear polyesters and copolyesters of glycols and high molecular weight terephthalic or isoterephthalic acid have been around since known for a long time. They are described, inter alia, in U.S. Patents 2,465,319 and 3,047,539, where the polyesters are described as are described as particularly advantageous for the production of films and as fiber formers. Articles made from polyalkylene terephthalate have many valuable properties including strength, toughness, Resistant to solvents, high gloss and the like. These items can be made using a variety of known processes including injection molding, rotary molding, blowing, extruding and the like in Depending on the shape of the desired product can be made.

Certain of these processes, particularly blow molding and extruding, require that the molten polyalkylene terephthalate have a suitably high melt viscosity, e.g.

wise over 10,0OO poise, showing a coincidence or to avoid bursting in the soft preformed state. It has been found that polyalkylene terephthalates with such high melt viscosity only with great difficulty in conventional bulk melt polymerization processes which are commonly used to make polyesters.

A useful class of such compositions are those obtained by incorporating a fire retardant amount of a fire retardant Are made fire retardant by means and optionally contain a reinforcing agent, such as glass fibers.

However, common fire retardant polyalkylene terephthalate compositions have Insufficient melt strengths to be successfully extruded into continuous and reproducible profiles to be able to, nor can these known fire-retardant polyester compositions without excessive deflection or sufficient Dimensional stability can be thermoformed during molding.

It has now been found that the use of branched polyalkylene terephthalate resins instead of unbranched resins in these fire-retardant compositions results in compositions which have greatly improved melt strength so that satisfactory processing of both thermoformed parts and reproducible extruded profiles can be achieved.

The invention relates to thermoplastic compositions with improved melt strength for molding, for example by injection molding, compression molding, transfer molding and the like which are characterized by

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a) a branched polyalkylene terephthalate resin having a high molecular weight and a melt viscosity of at least 15,000 poise containing a polyalkylene terephthalate having a high molecular weight and about 0.05 to 3 mol%, based on the terephthalate units of a branching component, the at least three ester-forming groups has, and

b) a fire retardant amount of a fire retardant agent.

The term "high molecular weight polyalkylene terephthalate resin" generally includes saturated condensation products of diols and dicarboxylic acids or reactive derivatives of this. Preferably they comprise condensation products of aromatic dicarboxylic acids or esters and aliphatic ones Diols. It is also possible to incorporate cyclic aliphatic linkages, such as those from 1,4-dimethylolcyclohexane to be delivered. In addition to the terephthalic acid hexes, other dicarboxylic acids such as adipic acid, naphthalene dicarboxylic acid, isophthalic and For example, o-phthalic acid can be used in an amount of about 0.5 to 15 mol% of the total acid units. Of the The alkylene component can also be varied and include units derived from ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,1O-decanediol, cycloaliphatic Diols, mixtures thereof, and the like can be obtained. The alkylene units preferably contain 2 to 6 carbon atoms and in particular the alkylene units are 1,4-butylene units, as these supply polyesters which crystallize very quickly from the melt.

Preferred polyesters are those from the class consisting of polymeric glycol terephthalates or isophthalates with high molecular weight and repeating units of the general formula:

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- ir-

in which η is an integer from 2 to 4, as well as mixtures of these esters including copolyesters of terephthalic and isophthalic acids up to about 30 mole percent isophthalic acid units.

Particularly preferred polyesters are ethylene terephthalate and poly-1,4-butylene terephthalate. Especially on the latter it should be noted that it crystallizes at such a favorable rate that it is suitable for injection molding without the need for a nucleating agent or long cycles, as is sometimes the case with polyethylene terephthalate necessary is.

The branching component used in the polyesters contains at least three ester-forming groups. It can be one which has a branch in the part of the acid unit of the polyester or in the part of the glycol unit or provides a hybrid formation. Examples of such branching components are tri- or tetracarboxylic acids such as trimesic acid, pyromellitic acid and lower alkyl esters thereof and the like or preferably polyols and particularly preferably tetrols such as pentaerythritol, triols such as trimethylolpropane or dihydroxycarboxylic acids and hydroxydicarboxylic acids and their derivatives such as dimethylhydroxyterephthalate and the same.

The relative amount of branching component used in the reaction mixture can vary, however

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it is preferably always kept to a smaller proportion, for example up to a maximum of 5 mol% for 100 moles Terephthalate units in the branched polyester. The range is preferably for the branching component in the esterification mixture (and generally that contained in the product) at 0.05 to 3 mol%, based on the terephthalate units. Particularly preferred is the range from about 0.1 to about 1 mol%, based on the Terephthalate component.

Processes for producing such polyesters are known per se; reference is made, for example, to US Pat. No. 2,465,319 and 3,047,539 and 3,692,744. In general, it is sufficient to use small amounts of branching components the terephthalic acid or the ester and an excess of alkylene glycol in the presence of a conventional polyester catalyst add, then heat to form a prepolymer, and finally under high vacuum to heat until the desired degree of polymerization is reached.

The molecular weight of the branched polyester should be high enough to provide a melt viscosity of at least Delivering 15,000 poise, but not so high that the branched polyester is no longer a thermoplastic is. For example, the molecular weight of the branched polyester should be sufficient to achieve a Melt viscosity in the range of about 15,000 to 100,000 poise.

Exemplary flame retardants that can be used in the invention are described in U.S. Patents, 3,830,771 and 3,833,685, 3,341,154, 3,915,926 and 3,671,487 as well as 3,681,281, 3,557,053 in the (S-PS 1 358 080.

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In general, the fire retardant additives include that a class of chemical compounds known per se are expedient according to the invention. Generally speaking The more important of these compounds contain chemical elements due to their ability to be fire resistant can be used, for example, bromine, chlorine, antimony, phosphorus and nitrogen. It is preferred that the fire retardant additives a halogenated organic compound (brominated or chlorinated), a halogen-containing one organic compound mixed with antimony oxide, elemental phosphorus or a phosphorus compound, a halogen-containing one Compound mixed with a phosphorus compound or compounds containing phosphorus-nitrogen bonds or a mixture of two or more of the foregoing compounds.

The amount of fire retardant additive that is used is not critical as long as it is present in smaller proportions relative to the mass - larger proportions will be the reduce physical properties - however, the amount must be sufficient so that the polyester resin is not flammable or is self-extinguishing. The amount varies according to the type of resin and the effectiveness of the additive. Generally, however, the amount of additive will be from 0.5 to 50 parts by weight per 100 parts of resin. A preferred one The range is 3 to 25 parts by weight, and particularly preferred is the addition of 8 to 12 parts by weight of the addition per 100 parts of resin. Smaller amounts of compounds with high concentrations of those elements necessary for the Fire retardancy will be sufficient; for example, elemental red phosphorus will be an area from 0.5 to 2.0 parts by weight per 100 parts resin preferred, while phosphorus in the form of triphenyl phosphate in an amount of about 25 parts by weight of phosphate per 100 parts of resin is used, etc. Halogenated aromatic carbons

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275643b

Hydrogen is used in an amount of 8 to 12 parts and synergistic substances such as antimony oxide in in an amount of about 2 to 5 parts by weight per 100 parts of resin.

Among the appropriate halogen-containing compounds are those with the following formula:

in which R is an alkenylene, alkylidene radical or a cycloaliphatic Chaining, for example a methylene, ethylene, propylene, isopropylene, isopropylidene, butylene, Isobutylene, amylene, cyclohexylene, cyclopentylidene group or the like, a linkage selected from the group consisting of ether, carbonyl, amine, a sulfur-containing one Link, for example sulfide, sulfoxide, sulfon, is a phosphorus-containing linkage or the like. R can also be composed of two or more alkylene or alkylidene radicals consist of radicals such as aromatic, amino, ether, carbonyl, sulfide, sulfoxide, sulfone, a phosphorus-containing residue or the like are connected. Other residues represented by R are dem Known to those skilled in the art.

Ar and Ar ¹ are mono- or polycarbocyclic aromatic radicals such as phenylene, biphenylene, terphenylene, naphthylene radicals or the like. Ar and Ar ¹ can be the same or different.

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Υ is a substituent from the group consisting of organic, inorganic or organometallic residues. The substituents represented by Y include

1. Halogen, for example chlorine, bromine, iodine or fluorine and

2. Ether radicals of the general formula OE, where E is a monovalent hydrocarbon radical similar to X, or

3. Monovalent hydrocarbon radicals of the type represented by R is, or

4. other substituents, for example nitro, cyano, etc., these substituents being essentially inert are provided that at least one and preferably two halogen atoms per aryl, e.g. phenyl, nucleus available.

X is a monovalent hydrocarbon radical, for example of the following type: an alkyl radical such as a methyl, ethyl, propyl, isopropyl, butyl, decyl radical or the like, an aryl radical such as phenyl, naphthyl, biphenyl, XyIyI, Tolyl radical or the like, an aralkyl radical such as a benzyl, Ethylphenyl radical or the like, cycloaliphatic radicals such as cyclopentyl, cyclohexyl radicals and the like. X includes also a monovalent hydrocarbon radical with inert substituents. If more than one remainder X is used these can be the same or different.

The letter d is an integer ranging from 1 to a maximum equivalent to the number of replaceable hydrogen atoms substituted on the aromatic rings containing Ar or Ar '. The letter e is an integer from 0 to a maximum controlled by the number of replaceable hydrogen atoms on R. The letters a, b, and c represent integers including O. If b is not 0, neither a nor c can be 0 . Otherwise, either a or c, but not both, can be 0. When b is 0, the aromatic radicals are represented by a different carbon

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Carbon bond linked together.

The hydroxyl and Y substituents on the aromatic radicals, Ar and Ar 'can be in the ortho, meta or para positions on the aromatic rings can be varied and the groups can relate to any possible geometric relationship have to each other.

The above formula includes biphenyls, of which the following are representative:

2,2-bis (3,5-dichlorophenyl) propane

Bis (2-chloropheny1) methane

Bis (2,6-dibromophenyl) methane

1,1-bis-4 (4-iodophenyl) ethane

1,2-bis (2,4-dichlorophenyl) ethane

1,1-bis- (2-chloro-4-iodophenyl) ethane

1,1-bis- (2-chloro-4-methylphenyl) ethane 1,1-bis (3,5-dichlorophenyl) ethane

2,2-bis-X3-phenyl-4-bromophenyl) ethane 2,6-bis (4,6-dichloronaphthyl) propane 2,2-bis (2,6-dichlorophenyl) pentane

2,2-bis (3,5-dichlorophenyl) hexane

Bis (4-chloropheny1) phenyl methane

Bis (3,5-dichlorophenyl) eyelohexylmethane Bis (3-nitro-4-bromophenyl) methane

Bis (4-hydroxy-2, δ-dichloro-S-raethoxyphenyl) methane 2,2-bis (3,5-dichloro-4-hydroxyphenyl) propane 2,2-bis (3-bromo-4-hydroxyphenyl) propane

The preparation of these or other useful biphenyls is known. Instead of the divalent aliphatic radical in the above examples, sulfide, sulfoxy, or the like may be substituted.

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Al *

The above formula also includes benzenes, for example 1,3-dichlorobenzene, 1,4-dibromobenzene, 1,3-dichloro-4-hydroxybenzene, Hexachlorobenzene, hexabromobenzene and biphenyls such as 2,2'-dichlorobiphenyl, 2,4'-dibromobiphenyl and 2,4'-dichlorobiphenyl.

Preferred fire retardant additives are aromatic Carbonate homopolymers with repeating units of the following formula:

(X ¹ )

0-C-O

1 2
in which R and R are a hydrogen atom, a lower alkyl

1 2
or phenyl radical and X and X are bromine or chlorine, while m and r are integers from 1 to 4. The production of these substances is known per se. Also preferred are aromatic carbonate copolymers in which 25 to 75 percent by weight of the repeating units contain chlorine- or bromine-substituted phenolic, glycol or dicarboxylic acid units, see for example US Pat. No. 3,915,926.

In addition, aromatic halogen compounds such as chlorinated benzene, brominated benzene, chlorinated biphenyl, chlorinated terphenyl, brominated biphenyl, brominated terphenyl or a compound containing two phenyl radicals separated by a divalent alkylene or oxygen group and with at least two chlorine or bromine atoms per phenyl nucleus and mixtures of at least two of the above compounds.

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-A-

As

In general, the preferred phosphorus compounds are selected from elemental phosphorus and organic phosphoric acids, phosphonates, phosphinates, phosphonites, phosphinites, phosphene oxides, phosphenes, phosphites or phosphates. Triphenylphosphine oxide is exemplary. This can be used alone or mixed with hexabromobenzene or a chlorinated biphenyl and optionally antimony oxide be used.

Typical of the phosphorus compounds preferred according to the invention are those with the general formula:

Xn

χι _ ρ »γ»

γι ι ι

in which X = S or 0 and η - 0 or 1, Y ¹ , Y "and Y ¹ · 'are identical or different and are alkyl-, cycloalkyl-, aryl-, alkyl-substituted aryl-, halogen-substituted aryl-, aryl-substituted alkyl -, alkyloxy, cycloalkyloxy, halogen-substituted alkyloxy, aryloxy, halogen-substituted aryloxy radical or a halogen atom. Two of the radicals Y can form a cyclic structure, while one or two of the radicals Y can be difunctional, in which case the compounds of short or long-chain compounds containing a large number of P atoms per molecule. Typical examples of suitable phosphorus compounds include triphenyl phosphate, diphenyl phenyl phosphate, phenyl diphenyl phosphinate, triphenyl phosphine, triphenyl phosphine oxide, tris (p-bromophenyl) phosphate, tris (p-bromophenyl) phosphate, tri-bromophenyl phosphate, Dibenzylphenyl phosphonate, poly (1,4-cyclohexylenedimethylene) phenylphosphonate, pentaerythritol bis (p-bromophenyl) phosphonate and the like e is the preferred fire retardant

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Tris (tribromophenyl) phosphate.

Also as fire retardant additives for the invention Masses are compounds that form phosphorus nitrogen bonds contain, such as phosphonitrile chloride, phosphoric ester amides, Phosphoric acid amides, phosphonic acid amides, phosphinic acid amides, Tris (aziridinyl) phosphine oxide or tetrakishydroxymethylphosphonium chloride. These fire retardant additives are commercially available.

Reinforcing agents which can optionally be used in the compositions according to the invention are known per se, they can be selected from the group consisting of metals such as aluminum, iron or nickel particles or the like or non-metals such as carbon fibers, silicates, acicular calcium silicate, asbestos, titanium dioxide , Potassium titanate and titanate whiskers, wollastonite, glass flakes and fibers. When a filler strength and rigidity of the
Does not improve mass, it is just a filler and not a reinforcing filler.

Although it is only necessary to use at least a reinforcing amount of the reinforcing filler generally the reinforcing compounds are about 10 to 60 percent by weight of the total compound of the reinforcing agent.

In particular, the preferred reinforcing fillers are made of glass, and it is usually preferred to use glass fibers made from lime aluminum borosilicate glass, which is relatively free of soda. This is known as Ε glass. However, other glasses are appropriate when electrical properties are not
important are, for example, the inferior soda glasses known as C glasses. The fibers can be known by

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Process for example by steam or air bubbles, flame bubbles or mechanical drawing. The fiber diameter ranges from about 0.0003 to 0.0019 cm however, not critical for the purposes of the invention. Glass fibers can be surface coatings in known Have ways to improve their reinforcement properties. Generally, best properties are reinforced with Obtained masses containing about 15 to 30 weight percent glass reinforcement.

The length of the glass fibers and whether or not they are bundled into filaments and the filaments are bundled in turn into yarns, ropes or rowings, woven into mats or the like, is essential for carrying out the invention not critical. In the production of the compositions according to the invention, it is expedient to use chopped glass fibers Strands with a length of about 0.32 to 2.54 cm, preferably less than 0.64 cm to be used. In objects which were formed from compositions according to the invention, even shorter lengths are encountered, since during manufacture there is a considerable reduction in the mass. However, this is desirable, as the best properties of thermoplastic injection molded articles are shown in which the fiber lengths are between about 0.000013 and 0.305 cm.

The compositions of the invention can be made by a variety of methods. One way is the fire retardant and reinforcement, e.g. glass fiber, if desired, in an extrusion mixer with the branched polyester resin to create pellets. The fire retardant and, if applicable the reinforcing agents are made up in a matrix

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branched polyester resin dispersed in the process. Another way is to use the fire retardant and the reinforcing agent, if the latter is used, with the branched polyester resin by dry blending mix and then either soften and crush on a grinder, or extrude and chop. The fire retardant and the reinforcing agent used, if any, can be mixed or granulated with the one branched polyester mixed and directly molded, for example by injection molding or transfer molding.

It is also important to use all ingredients, resin, fire retardants and, if necessary, common additives such as reinforcing agents, carefully rid of as much water as possible.

In addition, the preparation of the mass should be carried out in such a way that it is ensured that the residence time in the Machine short is that the temperature is carefully controlled, the frictional heat used and an intimate mixture between the resin, the fire retardant and any additives such as the reinforcing agent.

While not critical, best results are obtained when the ingredients are premixed, pelletized and processed then be molded. The premixing can be carried out in known facilities. For example, after careful Predrying the branched polyester resin, the fire retardant and optionally the reinforcing agent under vacuum at 100 ° C. for 12 h in a single-screw extruder loaded with a dry mix of the ingredients, the screw used having a long transition area has to ensure a suitable melting. On the other hand, a twin screw extruder, for example

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a 28 non Werner Pfleiderer machine with the resin and the Additives at the insertion opening and with the reinforcing agent be charged downstream thereof. In any case, a suitable machine temperature is around 232 to 238 ° C.

The premixed mass can be extruded and divided into moldable masses such as granules, pellets and the like will.

The crowds can be in any facility that is customary used for thermoplastic compositions. For example, with poly-1,4-butylene terephthalate good results with an injection molding machine of the Newbury type with usual cylinder temperatures, for example of 232 ° C and customary mold temperatures of 65.6 ° C, for example. On the other hand, with polyethylene terephthalate due to the lack of uniformity of crystallization from the inside to the outside in thick articles somewhat less conventional but still known techniques can be used. For example, a nucleating agent such as graphite or metal oxide, for example ZnO or MgO, can be incorporated during normal molding temperatures of at least 110 ° C can be used.

example 1

A dry mix of 69 parts by weight of a little containing branched poly-1,4-butylene terephthalate resin 0.21 mol% pentaerythritol as a branching component and with a melt viscosity of 40,000 to 50,000 poise, 26 parts by weight of an aromatic (copoly) carbonate of bisphenol A and tetrabromobisphenol A with a molar ratio of 50:50, 5 parts by weight of antimony oxide and minor Amounts of common stabilizer will be added too

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ÄO

processed a mass and extruded at 232 to 260 ° C from an extruder. After molding in a 85 g Van Dorn Injection molding machine with reciprocating screw achieved the following properties:

properties

Melt viscosity at 250 ° C (poise) 64,068

Heat deflection temperature at 18559 g / cm ² ( ⁰ C) 96 Izod impact strength (30.48 cm 453.59 g / 2.54 cm) 0.88 Gardner impact strength at 345.6 cm kg 10/10 pass tensile strength (g / cm ² ) 611.891

Elongation at break (%) 121

Flammability with respect to UL-94 at a

Thickness of 0.16 cm 94 V-O

When the masses are extruded they provide continuous and reproducible profiles. In thermoforming they deliver objects without excessive deflection and excellent dimensional stability.

If the example is repeated using a linear, i.e. unbranched, poly-1,4-butylene terephthalate, the mass provides shaped objects with lower resistance up to destruction by heat, with lower impact strength and lower elongation at break. At the most essential, however, is the fact that this replacement leads to a complete loss of the ability to become continuous and reproducible profiles to be extruded. In addition, these comparative masses show in thermoforming excessive deflection, the thermoformed articles having a large dimensional variation exhibit.

Instead of pentaerythritol as the branching compound of Example 1, trimethylolethane, trimethylolpropane, for example, can also be used or trimethyl trimesate can be used.

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Claims (17)

Claims 1. Thermoplastic compound with improved melt strength, marked by a) a branched polyalkylene terephthalate resin having a high molecular weight and a melt viscosity of at least about 15,000 poise containing a high molecular weight polyalkylene terephthalate and about 0.05 to about 3 mol%, based on the terephthalate units a branching component which contains at least three ester-forming groups, and b) a fire retardant amount of a fire retardant additive. 2. Composition according to claim 1, characterized in that the branching component from the group consisting of one Tricarboxylic acid, a tetracarboxylic acid and lower Alkyl esters thereof. 3. Mass according to claim 1, characterized in that the Branch component is a polyol. 4. Mass according to claim! 1, characterized in that the Branching component from the group consisting of a hydroxycarboxylic acid and a dihydroxycarboxylic acid and esters thereof. 5. Composition according to one of claims 1 to 4, characterized in that that the fire retardant is selected from the group consisting of an aromatic carbonate homopolymer with the following repeating units: 809825/0957 O-C-O 1 2
where R and R are hydrogen atoms, lower alkyl or Phe 1 2
nylreste, X and X are bromine or chlorine and m and r numbers from 1 to 4, and from an aromatic (copoly) carbonate, in which 25 to 75 percent by weight of the repeating units are chlorine- or bromine-substituted divalent phenol units and the remainder of the repeating units contain divalent phenol, glycol or dicarboxylic acid units, and mixtures thereof. 6. Composition according to one of claims 1 to 5, characterized in that that it contains a reinforcing amount of a reinforcing agent. 7. Composition according to claim 2, characterized in that the branching component Is trimethyl trimesate. 8. Composition according to claim 3, characterized in that the branching component Is pentaerythritol. 9. Composition according to claim 3, characterized in that the branching component is trimethylolpropane. 10. A composition according to claim 5, characterized in that the fire retardant is an aromatic (copoly) carbonate of bisphenol A and tetrabromobisphenol A in a molar ratio of 50:50. 809825/0957 11. Composition according to claim 6, characterized in that the reinforcing agent consists of glass fibers. 12. Composition according to claim 1, characterized in that the polyalkylene terephthalate has a high molecular weight is selected from the group consisting of polymeric glycol terephthalate and isophthalate esters and recurring Units of the formula Il 0 ^C C in which η is an integer from 2 to 4, and mixtures thereof. 13. Composition according to claim 1, characterized in that the high molecular weight polyalkylene terephthalate is poly-1,4-butylene terephthalate is. 14. Composition according to claim 10, characterized in that the fire retardant contains antimony oxide. 15. Thermoplastic mass with improved melt strength, characterized by a) a branched poly-1,4-butylene terephthalate resin with high molecular weight and a melt viscosity of at least about 15,000 poise High molecular weight poly-1,4-butylene terephthalate and about 0.05 to 3 mole percent based on the Terephthalate units of a branching component with at least three ester-forming groups and 809825/0957 - 30 - I » b) a fire retardant amount of a fire retardant containing an aromatic (copoly) carbonate in which 25 to 75 percent by weight of the repeating units are chlorine or bromine substituted divalent phenolic units and the remainder of the repeating units are divalent phenolic, glycolic or dicarboxylic acid units contain, and has antimony oxide. 16. Composition according to claim 15, characterized in that the The branching component is pentaerythritol. 17. Mass according to claim 16, characterized in that the Branching component is present in an amount from 0.1 to about mole percent based on the terephthalate units is. 809825/0957