GB1591836A - Polyester compositions which crystallise rapidly - Google Patents

Abstract

The thermoplastic composition contains, based on the total amounts of components a + b, a) 70-99.5% by weight of a high-molecular-weight polyalkylene terephthalate having an intrinsic viscosity of at least 0.6 dl/g, measured as a 0.5% strength by weight solution in a phenol/tetrachloroethane mixture in the weight ratio 1:1 at up to 25 DEG C, and b) 0.5-30% by weight of at least one product of the esterification of an aliphatic dicarboxylic acid having 3-10 carbon atoms and aliphatic, cycloaliphatic and/or araliphatic, monohydric or monohydric and dihydric alcohols having 1-12 carbon atoms, having a number average molecular weight of 132-2000. The composition is prepared by mixing the two components and homogenising the mixture in the melt. The composition can be mixed with reinforcing materials, auxiliaries and flameproofing agents and is an excellent starting material for the production of films, fibres and mouldings. During conversion, highly crystalline products are obtained at a high crystallisation rate.

Description

(54) POLYESTER COMPOSITIONS WHICH CRYSTALLISE RAPIDLY (71) We, BAYER AKTIENGESELLSCHAFT, a body corporate organised and existing under the laws of Leverkusen of the Federal Republic of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:- The present invention relates to highly crystallinethermoplastic compositions which consist of a high-molecular weight polyalkylene terephthalate and an esterification product which causes the composition to crystallize rapidly.

Polyalkylene terephthalates have achieved considerable importance as raw materials for the production of fibers, films and moldings. Because of their partially crystalline structure, they possess outstanding properties such as, for example, high resistance to wear, advantageous creep characteristics and high dimensional accuracy, and are, therefore, particularly well suited to the production of moldings which are subjected to high mechanical stress and heat. An additional improvement in the mechanical properties can be achieved by incorporating reinforcing materials, for example, glass fibers (British Patent Specification 1,111,012, U.S. Patent Specification 3,368,995 and DT-AS (German Published Specification) 2,042,447).

Because of its particular physical properties, polyethylene terephthalate (PET) is especially suitable for the production of fiber products and films.

The production of moldings from polyethylene terephthalate by injection molding is, however, more difficult, since high mold temperatures (about 140"C) and relatively long pressing times are necessary. This serious disadvantage hinders the processing of polyethylene terephthalate by injection molding to an exceptional degree, despite its high rigidity and heat distortion resistance.

Because of their higher rate of crystallization, polypropylene terephthalate (PPT) and polybutylene terephthalate (PBT) do indeed require shorter pressing times and lower mold temperatures (about 80"C) but, compared with polyethylene terephthalate, these compounds possess poorer physical properties and, in particular, a lower heat distortion resistance.

There has, now, been no lack of attempts to provide polycondensation products in which the good properties both of polyethylene terephthalate and of polypropylene terephthalate and polybutylene terephthalate are combined. Thus, for example, it is known that the tendency of polyethylene terephthalate to crystallize can be improved by nucleation with finely divided solid inorganic substances (Netherlands Patent Specification 6,511,744).

High crystallinity ensures hardness, dimensional stability and stability of shape even at higher temperatures. This high crystallinity should be achieved as rapidly as possible so that an optimum level of properties is obtained. In addition, the injection cycle, the length of which also determines the economy, depends on the mold dwell time. These cycles are relatively long even when the mold temperatures for the polyethylene terephthalate are high and, therefore, make it difficult for polyethylene terephthalate to advance during the production of injection moldings.

In addition, it has long been an earnest desire of the manufacturers of polyesters also to produce other polyalkylene terephthalates with a higher rate of crystallization and higher crystallinity.

It has now been found, surprisingly, that polyalkylene terephthalate compositions crystallize more rapidly when they contain 0.5-30% by weight, relative to the polyalkylene terephthalate, of certain aliphatic dicarboxylic acid esters.

The present invention makes it possible to more rapidly achieve the degree of crystallinity required for high dimensional stability and thus to process the polyester compositions using greatly shortened injection cycles. A further advantage of the polyester compositions according to the invention lies in the lowering of the mold temperature, without this resulting in impairment of the good crystallization properties. As a result, the injection molding composition cools more rapidly and this further shortens the mold dwell time.

The invention relates to highly crystalline thermo-plastic compositions which do not contain a foaming agent and which crystallize rapidly comprising a. 7099.5, and preferably 85-99.5,% by weight of a high-molecular weight polyalkylene terephthalate which has an intrinsic viscosity of at least 0.6 dl/g and preferably of at least 0.8 dl/g (measured as a 0.5 /O strength by weight solution in a phenol/tetrachloroethane mixture in a weight ratio of 1::1 at 250C) and in which the co-condensed acid radicals consist of at least 90 mol% of radicals of terephthalic acid and 0 to 10 molt/, of radicals of another acid or acids selected from aromatic dicarboxylic acids with 6 to 14 carbon atoms, aliphatic dicarboxylic acids with 4 to 8 carbon atoms and cycloaliphatic dicarboxylic acids with 8 to 12 carbon atoms, and the co-condensed alcohol radicals consist of at least 90 molt/, of radicals of one or more of propane - 1,3 - diol, butane - 1,4 - diol, pentane - 1,5 - diol, hexane 1,6 - diol, cyclohexane - 1,4 - dimethanol or ethylene glycol and 0 to 10 molt/, of another diol or diols selected from aliphatic diols with 3 to 8 carbon atoms, cycloaliphatic diols with 6 to 15 carbon atoms and araliphatic diols with 6 to 21 carbon atoms, and b. 0.5-30, and preferably 0.5-15, /n by weight of an esterification product of an aliphatic dicarboxylic acid with 3-10 C atoms and an epoxide-free alcohol or alcohols selected from aliphatic, cycloaliphatic and araliphatic mono-hydric and dihydric alcohols with 1--12 C atoms, which esterification product should have a molecular weight, determined as the number-average, of 132-2,000. The esterification product is preferably one based at least partially on a monohydric alcohol or alcohols, and when the esterification product is one formed from 3 or less molecules of alcohol and acid and the acid has 10 carbon atoms, the amount of esterification product should be at least 5% by weight.

The percentages by weight indicated for a. and b. relate to the sum of the components a. and b.

The present invention also relates to a process for the preparation of highly crystalline thermoplastic compositions which crystallize rapidly, characterized in that 70-99.5, and preferably 85-99.5, / > by weight of a said high-molecular weight polyalkylene terephthalate with an intrinsic viscosity of at least 0.6 dl/g and preferably of at least 0.8 dl/g and 0.5-30, and preferably 0.5-15, /" by weight of the said esterification product of an aliphatic dicarboxylic acid with 3-10 C atoms and aliphatic, cycloaliphatic or araliphatic monohydric or dihydric alcohols with 1--12 C atoms, which esterification product should have a molecular weight, determined as the number-average, of 132-2,000, are mixed together and homogenized in the melt.

The present invention further relates to a process for manufacturing a moulded article, which process comprises injection moulding the article from a composition according to the invention at a mould temperature below 140"C, preferably from 107"C to 1120C.

The acid radicals co-condensed in the polyalkylene terephthalate a. consist to the extent of at least 90 mol /, of radicals of terephthalic acid and 0 to 10 mol /" of radicals of another acid or acids selected from aromatic dicarboxylic acids with 6' 14 C atoms, aliphatic dicarboxylic acids with 4-8 C atoms and cycloaliphatic dicarboxylic acids with 8-12 C atoms.

Phthalic acid, isophthalib acid, naphthalene - 2,6 - dicarboxylic acid, diphenyl - 4,4' - dicarboxylic acid, adipic acid, sebacic acid and cyclohexanediacetic acid may be mentioned as an example of such dicarboxylic acids.

The alcohol radicals co-condensed in the poly-alkylene terephthalate a.

consist to the extent of at least 90 mol /" of radicals of propane - 1,3 - diol, butane - 1,4 - diol, pentane - 1,5 - diol, hexane - 1,6 - diol, cyclohexane - 1,4 dimethanol and preferably ethylene glycol and to the extent of 0 to 10 mol /^ of radicals of another diol or diols selected from aliphatic diols with 3-8 C atoms, cycloaliphatic diols with 6-15 C atoms and araliphatic diols with 6-21 C atoms.

Examples of such diols which may be listed are 3 - methylpentane - 2,4 - diol, 2 - methylpentane - 1,4 - diol, 2,2,4 - tri - methylpentane - 1,3 - diol, 2 ethylhexane - 1,3 - diol, 2,2 - diethyl - propane - 1,3 - diol, hexane - 1,3 - diol, 1,4 - di - (p - hydroxyethoxy) - benzene, 2,2 - bis - (4 - hydroxycyclohexyl) propane, 2,4 - dihydroxy - 1,1,3,3 - tetramethylcyclobutane, 2,2 - bis - (3 - A - hydroxyethoxy - phenyl) - propane and 2,2 - bis - (4 - hydroxy - propoxy phenyl) - propane.

Of course, the polyalkylene terephthalates can be branched by trihydric or tetrahydric alcohols or tribasic or tetrabasic acids, as is described, for example, in DT-OS (German Published Specification 1,900,270). Suitable branching agents are, for example, trimesic acid, trimellitic acid, trimethylolpropane and trimethylolethane and pentaerythritol. It is advisable to employ not more than 1 mol %, relative to the acid component, of branching agents.

The polyalkylene terephthalates can be prepared in a manner which is in itself known by I. esterifying or trans-esterifying terephthalic acid and/or the corresponding dialkyl terephthalates, preferably the dimethyl ester, with 1.05 to 5.0, and preferably 1.4--3.6 mols of the diols, relative to I mol of the dicarboxylic acid component and, optionally, the branching agent, in the presence of esterification catalysts and/or transesterification catalysts and II. subjecting the reaction products thus obtained to a poly-condensation reaction in the presence of polycondensation catalysts at between 200 and 300"C under reduced pressure ( < 1 mm Hg).

Both step I and step II of the condensation reaction are carried out in the presence of catalysts, such as are described, for example, by R. E. Wilfong in J.

Polym. Sci. 54, 385 (1961). They are employed in amounts of 0.001 to 0.2% by weight, relative to the dicarboxylic acid component.

Subsequently, inhibitors, such as are described, for example, by H. Ludewig, Polyesterfasern (Polyester Fibers), 2nd edition, Akademie-Verlag, Berlin 1974, can be added in order to inhibit the catalysts suitable for catalyzing the first step of the reaction after reaction step I has ended and to increase the stability of the end product. Examples of such inhibitors are phosphoric acid and phosphorous acid and the aliphatic, aromatic or araliphatic esters thereof, for example, alkyl esters with 6-18 C atoms in the alcohol component, phenyl esters, the phenyl radicals of which are optionally substituted by 1--3 substituents with 6-18 C atoms, such as trinonylphenyl phosphate, dodecylphenyl phosphate or triphenyl phosphate.These inhibitors are usually employed in amounts of 0.01--0.60/, by weight, relative to the dicarboxylic acid component.

In order to obtain an even higher molecular weight, the polyalkylene terephthalates can be subjected to a solid phase polycondensation reaction. In this case, usually, the granulated product is subjected to a polycondensation reaction in the solid phase in a stream of nitrogen or in vacuo under a pressure of less than 1 mm Hg and at a temperature which is 606 C below the melting point of the polymer.

The compounds to be employed as esterification product b. preferably correspond to the formula

wherein R' denotes H or a linear or branched aliphatic, cycloaliphatic or araliphatic monovalent radical or a linear or branched aliphatic, cycloaliphatic or araliphatic hydroxyl substituted radical, each with 1--12 C atoms, R2 denotes a linear or branched aliphatic, cycloaliphatic or araliphatic divalent radical with 1--12 C atoms.

n denotes an integer from 1 to 8 and x denotes 0 or an integer from 1 to 15, and when x denotes 0, R is not hydrogen, The esterification product having a number-average molecular weight of 132 to 2,000.

Of course, mixtures of different compounds which fall under the above formula can also be employed.

The esterification products b. can be prepared by esterification or transesterification of the dicarboxylic acids and/or the corresponding dialkyl derivatives with the monofunctional or bifunctional alcohols.

A detailed description of the various methods of preparation is given by H.

Henecka et al in Houben-Weyl, Volume VIII, page 359-680 (1952) and by E.

Miller in Houben-Weyl 14/2 (1963), 1.

Preferred esterification products b. are those which are derived from adipic acid or sebacic acid as the dicarboxylic acid, 2 - ethylhexane - 1,3 - diol, 2,2,4 trimethylpentane - 1,3 - diol, butane - 1,3 - diol, hexane - 1,6 - diol or butane 1,4 - diol as the diol component and 2 - ethylhexanol, 3,5,5 - trimethylhexanol or n-butanol as the monohydric alcohol component.

Examples of suitable aliphatic carboxylic acid esters are: adipic acid di - (2 ethylhexyl) ester, adipic acid di-isononyl ester, adipic acid di-n-butyl ester, poly (butane - 1,3 - diol adipate, poly - (hexane - 1,6 - diol adipate), poly - (butane 1,4 - diol adipate, sebacic acid dibutyl ester, sebacic acid dioctyl ester, sebacic acid dibenzyl ester, sebacic acid 2 - ethylhexyl ester, azelaic acid dioctyl ester, azelaic acid dihexyl ester and azelaic acid diamyl ester.

The preparation of the polyester compositions according to the invention, which crystallize rapidly, from a polyalkylene terephthalate a. and an esterification product b. can be carried out in commercially available mixing equipment.

Examples of suitable equipment are kneaders, single screw extruders and twin screw extruders. For further processing, the resulting mixture can be granulated after the melt has solidified. In this case also, a solid phase post-condensation reaction can follow.

In order to provide protection against the thermo-oxidative degradation, the customary amounts, preferably 0.001 to 0.5O,' hy weight, relative to the unfilled and unreinforced polyalkylene terephthalates, of stabilizers can be added to the thermoplastic compositions according to the invention.Examples of suitable stabilizers are phenols and phenol derivatives, preferably sterically hindered phenols which contain alkali substituents with 1--6 C atoms in the two o-positions relative to the phenolic hydroxyl group, amines, preferably secondary arylamines and their derivatives, phosphates and phosphites, preferably their aryl derivatives, quinones, copper salts of organic acids and addition compounds of copper-(I) halides with phosphites, such as, for example, 4,4' - bis -(2,6 - di - tert. butylphenol), 1,3,5 - trimethyl - 2,4,6 - tris - (3,5 - di - tert. - butyl - 4hydroxy - benzyl) - benzene, 4,4' - butylidene - bis- (6- tert. - butyl - m cresol), 3,5 - di - tert. - butyl - 4 - hydroxy - benzyl - phosphonie acid diethyl ester, N,N' - bis - (A - naphthyl) - p - phenylenediamine, N,N' - bis - (I methylheptyl) - p - phenylenediamine, phenyl - - naphthylamine, 4,4' - bis (a,a dimethylbenzyl) - diphenylamine, 1,3,4 - tris - (3,5 - di - tert. - butyl - 4 hydroxy - hydroeinnamoyl) - hexahydro - s - triazine, hydroquinone, p benzoquinone, toluhydroquinone, p - tert. - butyl - pyrocatechol, chloranil, naphthoquinone, copper naphthenate, copper octoate, Cu(I)Cl/triphenyl phosphate, Cu(l)Cl/trimethyl phosphite, Cu(I)Cl/tris - chloroethyl phosphite, Cu(I)Cl/tripropyl phosphite and p - nitrosodimethylaniline.

The polyester compositions according to the invention can be reinforced with reinforcing materials. Metals, silicates, carbon and glass, mainly in the form of fibers, fabrics or mats, have proved useful as reinforcing materials. Glass fibers are a preferred reinforcing material.

In addition, if desired, inorganic or organic pigments, dyestuffs, lubricants and mold release agents, such as zinc stearate and montan waxes, and UV absorbers can be added in customary amounts.

In order to obtain flame-resistant products, 2-20% by weight, relative to the molding composition, of flameproofing agents which are in themselves known, for example, halogen-containing compounds, elementary phosphorus or phosphorus compounds, phosphorus/nitrogen compounds, antimony trioxide or mixtures of these substances, preferably antimony trioxide, decabromobiphenyl ether and tetrabromobisphenol A polycarbonate, can be added.

The rate of crystallization of the polyester compositions according to the invention can be further increased by adding 0.01-1% by weight, relative to the unfilled and unreinforced polyester of nucleating agents. Suitable nucleating agents are the compounds known to those skilled in the art, such as those described, for example, in Kunststoff-Hanbuch (Plastics Handbook), Volume VIII, "Polyester" ("Polyesters"), Carl Hanser Verlag, Munich, 1973, page 701.

The polyester compositions according to the invention are excellent starting materials for the production of films and fibers and preferably for the production of moldings of all types by injection molding.

Examples In order to determine the processing cycle time which can be achieved, the injection mold for a gearwheel (040 mm, thickness 7 mm) was used in which the injection molding was pressed out of the mold by four ejector pins. The injection cycle with which the ejector pins just no longer penetrated into the finished injection molding and the injection molding fell out of the mold without difficulty was determined.

Table 1 gives the cooling times of the mold (i.e. the time interval between end of injection and removal of the extruder from the mold and the opening of the mold) and the total injection cycle times for several polyester resin compositions according to the invention based on PET and aliphatic carboxylic acid esters (Examples 1--7) compared with non-modified PET. The PET used had an intrinsic viscosity of at least 0.6 dl/g measured as defined above and each ester used had a molecular weight, determined as the number-average, of 132 to 2,000.

TABLE 1 Processing Conditions Total Injection Amount Cylinder Mold Molding (% by Temperature Temperature Cooling Cycle Example Type of Carboxylic Acid Weight) ("C) ("C) Time (Seconds) I Adipic acid di-(2 ethylhexyl)-ester 5 260 108 3 12.5 2 Adipic acid di-n butyl ester 5 260 107 8 17.5 3 Adipic acid diisononyl ester 5 260 112 6 15.5 4 Adipic acid benzyl octylester 5 260 110. 14 23.5 5 Poly-(butane- 1,3 dioladipate) 5 260 110 16 25.5 6 Poly-(butane- 1,4- dioladipate) 5 260 110 8 17.5 7 Poly-(hexane- 1,6 diol adipate) 5 260 110 8 17.5 8 - - 270 140 30 39.5 Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose, and that variations can be made therein by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

WHAT WE CLAIM IS: 1. A highly crystalline thermoplastic composition which does not contain a foaming agent and which crystallizes rapidly, comprising a) 70 to 99.5% by weight of a high molecular weight polyalkylene terephthalate which has an intrinsic viscosity of at least 0.6 dUg (measured as a 0.5 strength by weight solution in a phenol/tetrachloroethane mixture in a weight ratio of 1::1 at 25"C) and in which the co-condensed acid radicals consist of at least 90 mol% of radicals of terephthalic acid and 0 to 10 molt/, of radicals of another acid or acids selected from aromatic dicarboxylic acids with 6 to 14 carbon atoms, aliphatic dicarboxylic acids with 4 to 8 carbon atoms and cycloaliphatic dicarboxylic acids with 8 to 12 carbon atoms, and the co-condensed alcohol radicals consist of at least 90 molt/, of radicals of one or more of propane - 1,3 - diol,butane - 1,4 - diol, pentane - 1,5 - diol, hexane - 1,6 - diol, cyclo - hexane - 1,4 - dimethanol or ethylene glycol and 0 to 10 mol% of another diol or diols selected from aliphatic diols with 3 to 8 carbon atoms, cyclo-aliphatic diols with 6 to 15 carbon atoms and araliphatic diols with 6 to 21 carbon atoms, and

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

Claims (16)

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

   The polyester compositions according to the invention are excellent starting materials for the production of films and fibers and preferably for the production of moldings of all types by injection molding.

   Examples In order to determine the processing cycle time which can be achieved, the injection mold for a gearwheel (040 mm, thickness 7 mm) was used in which the injection molding was pressed out of the mold by four ejector pins. The injection cycle with which the ejector pins just no longer penetrated into the finished injection molding and the injection molding fell out of the mold without difficulty was determined.

   Table 1 gives the cooling times of the mold (i.e. the time interval between end of injection and removal of the extruder from the mold and the opening of the mold) and the total injection cycle times for several polyester resin compositions according to the invention based on PET and aliphatic carboxylic acid esters (Examples 1--7) compared with non-modified PET. The PET used had an intrinsic viscosity of at least 0.6 dl/g measured as defined above and each ester used had a molecular weight, determined as the number-average, of 132 to 2,000.

   TABLE 1 Processing Conditions Total Injection Amount Cylinder Mold Molding (% by Temperature Temperature Cooling Cycle Example Type of Carboxylic Acid Weight) ("C) ("C) Time (Seconds) I Adipic acid di-(2 ethylhexyl)-ester 5 260 108 3 12.5

   2 Adipic acid di-n butyl ester 5 260 107 8 17.5

   3 Adipic acid diisononyl ester 5 260 112 6 15.5

   4 Adipic acid benzyl octylester 5 260 110. 14 23.5

   5 Poly-(butane- 1,3 dioladipate) 5 260 110 16 25.5

   6 Poly-(butane- 1,4- dioladipate) 5 260 110 8 17.5

   7 Poly-(hexane- 1,6 diol adipate) 5 260 110 8 17.5

   8 - - 270 140 30 39.5 Although the invention has been described in detail in the foregoing for the purpose of illustration, it is to be understood that such detail is solely for that purpose, and that variations can be made therein by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

   WHAT WE CLAIM IS: 1. A highly crystalline thermoplastic composition which does not contain a foaming agent and which crystallizes rapidly, comprising a) 70 to 99.5% by weight of a high molecular weight polyalkylene terephthalate which has an intrinsic viscosity of at least 0.6 dUg (measured as a 0.5 strength by weight solution in a phenol/tetrachloroethane mixture in a weight ratio of 1::1 at 25"C) and in which the co-condensed acid radicals consist of at least 90 mol% of radicals of terephthalic acid and 0 to 10 molt/, of radicals of another acid or acids selected from aromatic dicarboxylic acids with 6 to 14 carbon atoms, aliphatic dicarboxylic acids with 4 to 8 carbon atoms and cycloaliphatic dicarboxylic acids with 8 to 12 carbon atoms, and the co-condensed alcohol radicals consist of at least 90 molt/, of radicals of one or more of propane - 1,3 - diol,butane - 1,4 - diol, pentane - 1,5 - diol, hexane - 1,6 - diol, cyclo - hexane - 1,4 - dimethanol or ethylene glycol and 0 to 10 mol% of another diol or diols selected from aliphatic diols with 3 to 8 carbon atoms, cyclo-aliphatic diols with 6 to 15 carbon atoms and araliphatic diols with 6 to 21 carbon atoms, and

   b) 0.5 to 30 /n by weight of an esterification product of an aliphatic dicarboxylic acid with 3 to 10 carbon atoms and an epoxide-free alcohol or alcohols selected from aliphatic, cycloaliphatic and araliphatic monohydric and dihydric alcohols with 1 to 12 carbon atoms, said esterification product having a molecular weight, determined as the number-average, of 132 to 2,000 and when the esterification product is one formed from 3 or less molecules of alcohol and acid and the acid having 10 carbon atoms, the amount of esterification product is from 5 to 30% by weight.
2. 2. A composition according to claim 1, comprising 85 to 99.5% by weight of the polyalkylene terephthalate and 0.5 to 15% by weight of the esterification product.
3. 3. A composition according to claim 1 or claim 2, in which the polyalkylene terephthalate has an intrinsic viscosity of at least 0.8 dl/g.
4. 4. A composition according to any one of the preceding claims, wherein the esterification product is based on sebacic acid, adipic acid or both.
5. 5. A composition according to any one of the preceding claims, wherein the co-condensed alcohol radicals consist of at least 90 mol% of ethylene glycol radicals.
6. 6. A composition according to any one of the preceding claims, wherein the polyalkylene terephthalate consists essentially of ethylene glycol and terephthalic acid residues.
7. 7. A composition according to any one of the preceding claims, wherein the esterification product is of an aliphatic dicarboxylic acid with 3 to 9 carbon atoms.
8. 8. A composition according to any one of the preceding claims, wherein the esterification product is at least partially based on monohydric alcohols.
9. 9. A composition according to claim 8, wherein the esterification product is an esterification product of sebacic or adipic acid or both with a diol selected from 2 ethylhexane - 1,3 - diol; 2,2,4 - trimethylpentane - 1,3 - diol; butane - 1,3 - diol; hexane - 1,6 - diol; and butane - 1,4 - diol; and/or with a monohydric alcohol selected from 2 - ethyl - hexanol, 3,5,5 - trimethyl hexanol and n - butanol.
10. 10. A process for the production of a composition as defined in any one of the preceding claims, in which 70 to 99.5 /n by weight of said high-molecular weight polyalkylene terephthalate and 0.5 to 30'/ by weight of said esterification product are mixed together and homogenized in the melt.
11. 11. A process according to claim 10, in which the polyalkylene terephthalate has been produced by esterifying or transesterifying an acid component which is at least 90 molt/, of terephthalic acid or a dialkylterephthalate with 1.05 to 5.0 mols of a diol component, relative to 1 mol of the dicarboxylic acid component, in the presence of an esterification catalyst and/or transesterification catalyst and subjecting the product thus obtained to a poly-condensatjon reaction in the presence of a polycondensation catalyst at from 200 to 3000C under reduced pressure.
12. 12. A composition according to claim 1, when produced by a process according to claim 10 or claim 11.
13. 13. A composition according to claim 1, substantially as hereinbefore described in any one of Examples 1 to 5.
14. 14. A composition according to claim 1, substantially as hereinbefore described in Example 6 or Example 7.
15. 15. A process for manufacturing a moulded article, which process comprises injection moulding the article from a composition according to any one of claims 1 to 8 at a mould temperature below 140"C.
16. 16. A process according to claim 15 wherein the mould temperature is from 107"C to 1120C.