Abstract: Compositions comprising a high molecular weight polyester resin derived from a cyclohexanedimethanol and a hexacarbocyclic dicarboxylic acid or mixture of such resins and, optionally, a second linear high molecular weight polyester, optionally further combined with an effective, impact strength-improving amount of a thermoplastic elastomer, such as a polyether ester or a polyetherimide ester, with relatively high loadings of fillers selected from zinc oxide, barium sulfate, zirconium oxide, zirconium silicate, strontium sulfate or a mixture of any of such fillers, provide highly dense thermoplastic molded articles with improved impact strength and properties suitable to replace ceramics and filled thermosets in many important applications.

Abstract: A flame retardant linear polyester comprising the product of a polyethylene terephthalate prepolymer, bis-hydroxy alkyl bibenzoate and a flame-retarding amount of a carboxy-phosphinic acid, a process for producing the polyester and products produced from the polyester are disclosed.

Abstract: There is disclosed a polyester resin composition comprising: (a) 50 to 70 parts by weight of a polyester resin composed mainly of a repeating unit of butylene terephthalate; (b) 30 to 50 parts by weight of a polyester resin composed mainly of a repeating unit of ethylene terephthalate; (c) 0.1 to 10 parts by weight of a polyalkylene glycol derivative having at least one end group of carboxylate and alkyl ether, per 100 parts by the total weight of the polyester resins (a) and (b); and if necessary or required, (d) not more than 120 parts by weight of an inorganic reinforcing agent, per 100 parts by the total weight of the polyester resins (a) and (b).

Abstract: A flame retardant linear polyester comprising the product of recycled polyethylene terephthalate, bis-hydroxy alkyl bibenzoate and a flame-retarding amount of a carboxy-phosphinic acid, a process for producing the polyester and products produced from the polyester are disclosed.

Abstract: An improved liquid crystalline polymer blend is produced by mixing a preformed thermotropic liquid crystalline polymer in the melt phase with reactants needed to form a second liquid crystalline polymer under conditions sufficient to form the second liquid crystalline polymer. The resulting blends are anisotropic and have improved morphology and improved melt processability. The method is particularly useful when the second liquid crystalline polymer is biphasic or is difficult to synthesize or process in the melt.

Abstract: This invention provides weatherable thermosetting powder coating compositions based on 1,2-cyclohexanedicarboxylic acid and 2,2,4,4-tetramethyl-1,3-cyclobutanediol. Coatings from this invention exhibit far superior QUV (313 bulb) resistance than compositions based on resins prepared from 1,3-and 1,4-cyclohexanedicarboxylic acid and are 20 times better than standard aromatic resin using the same cross-linking chemistry.

Abstract: Random and block copolyesters which are liquid crystalline can be formed containing: (a) alkoxy-substituted para-phenylene terephthalate groups (i.e., derived from an analogously substituted hydroquinone reagent); and (b) alkylene-terephthalate groups (e.g., where the alkylene moiety contains 2 to 10 carbon atoms).

Abstract: ABA block copolymers having saturated polyester midblocks "B" and unsaturated polyester condensation end blocks A of molecular weight from about 100 to 500 or 600 are described which increase the flexural strain to failure of unsaturated polyester or vinyl ester resins. These ABA block copolymers are generally compatible with unsaturated polyester resins and increase flexural strain by a different mechanism than used by incompatible rubbery polymers. These ABA block copolymers are compatible with the unsaturated polyester compositions and do not phase separate.

Abstract: This invention provides certain blue substituted 1,4-bis(2,6-dialkylanilino) anthraquinones in combination with selected red anthraquinone and anthrapyridone (3H-dibenz[f,ij]isoquinoline-2,7-dione) compounds which provide a toner system useful in imparting a desirable neutral to slightly blue hue to polyesters having a yellow appearance. The thermally stable colored compounds can have polyester reactive groups and are preferably incorporated into the polyester polymer structure during polymerization.

Abstract: The present invention provides a polyester film for processing of a metal sheet, which shows excellent molding-processability when it is laminated onto a metal sheet and the laminated metal sheet is made into a can by deep drawing or the like and which is suitable and useful for production of a metal can having excellent heat resistance, impact resistance and flavor-retaining property.A polyester film used for lamination onto a metal sheet for processing of said metal sheet, characterized in that the film is formed from 99 to 60% by weight of a copolyester, as the component A, having an ethylene terephthalate unit as the main recurring unit and having a melting point of 210 to 245.degree. C. and 1 to 40% by weight of a polybutylene terephthalate or a copolyester, as the component B, having a butylene terephthalate unit as the main recurring unit and having a melting point of 180 to 223.degree. C., and further comprising a lubricant having an average particle diameter of 2.5 .mu.

Abstract: The present invention relates to thermoformed plastic articles such as frozen food trays which exhibit unexpectedly high impact strength at low temperatures. The articles are obtained from polyester blends containing 88 to 99 weight percent of a poly(ethylene terephthalate) resin and 1 to 12 weight percent of a poly(1,4-cyclohexylenedimethylene terephthalate) resin which contains at least 30 mole percent of 1,4-cyclohexanedimethanol.

Abstract: A polyester resin (A) having branched chain, a reduction viscosity (.eta. sp/c) of not less than 0.7, and a Z average molecular weight (Mz) relative to standard polystyrene of not less than 250.times.10.sup.3 and not more than 800.times.10.sup.3, a polyester resin composition comprised of resin (A) and a polyester resin (B) without branched chain and having a reduction viscosity (.eta. sp/c) of not less than 0.7., and a polyester resin composition comprised of resin (A) and a polyester resin (C) having branched chain and a melting point lower than that of the polyester resin (A). The sealant made from the polyester resin (A), or the resin compositions of the present invention is superior in heat-sealing properties, flavor retention, and film moldability (extrusion processing characteristics), and is suitable for a sealant for paper and plastic food containers.

Abstract: The invention relates to polyesters for use in outdoor-durable coating systems such as, for instance, coil coating systems. The polyester according to the invention is based on at least 50 moles % 1,4-cyclohexanedicarboxylic acid and a hexahydrophathalic acid (anhydride) as acid components. Up to a maximum of 50 moles % the polyester may be based also on acid components such as, for instance, isophthalic acid, terephthalic acid, adipic acid, sebacic acid, decanedicarboxylic acid and/or dimerized fatty acids or acid anhydrides such as, for instance, phthalic anhydride and succinic anhydride.

Abstract: The present invention relates to acid-curing aqueous coating compositions, in particular for the coating of finish sheeting and continuous edging, which contain aminoplast resin and hydroxyl-containing polyesters, wherein the polyester is prepared froma) 33 to 55 mol % of a dicarboxylic acid component obtained froma.sub.1) 50 to 100 mol % of olefinically unsaturated aliphatic dicarboxylic acidsa.sub.2) 0 to 50 mol % of saturated aliphatic dicarboxylic acidsa.sub.3) 0 to 50 mol % of saturated aliphatic dicarboxylic acids andb) 67 to 45 mol % of a polyol component obtained fromb.sub.1) 20 to 90 mol % of at least one monomeric and/or oligomeric glycol having 2 to 4 carbon atoms per glycol segment and number average molecular weights smaller than 200b.sub.2) 5 to 30 mol % of at least one polymeric glycol having 2 to 4 carbon atoms per glycol segment and a number average molecular weight between 300 and 1000 andb.sub.

Abstract: New compounds including bis-.beta.-hydroxy ethyl bibenzoate containing less than 2.5%, and preferably less than 1%, diethylene glycol and a process for the production of the bis-.beta.-hydroxy ethyl bibenzoate by the condensation of 4,4'-biphenyl dicarboxylic acid and ethylene glycol at low temperature and pressure in the presence of a catalyst are disclosed. Use of the compounds to produce polyesters is also disclosed.

Abstract: A composition of polyester resins comprising diblock copolymers formed of two different polyester blocks joined by a bifunctional radical deriving from a dianhydride of a tetracarboxylic acid. The compositions are prepared by a reaction in the solid state of two different polyesters in the presence of a dianhydride of a tetracarboxylic acid.

Abstract: Provided are crosslinkable semicrystalline polyester plasticizers useful in thermosetting powder coating compositions. The plasticizers of the present invention are preferably comprised of residues of 1,6-hexanediol and 1,12-dodecanedioic acid, and optionally, residues of trifunctional acids or polyols such as trimethylol-propane, glycerol, trimellitic acid, and the like. The thermosetting powder coating compositions also provided by the present invention exhibit markedly superior properties when compared to compositions lacking said plasticizer. Such coatings exhibit better smoothness, less orange peel, better impact strength and flexibility. In the case of the less-reactive crosslinker such as self-blocked isophorone isocyanate (IPDI), the plasticizers greatly improve the reactivity of the composition and reduce the cure requirement.

Abstract: This invention provides certain blue substituted 1,4-bis(2,6-dialkylanilino) anthraquinones in combination with selected red anthraquinone and anthrapyridone (3H-dibenz[f,ij] isoquinoline-2,7-dione) compounds which provide a toner system useful in imparting a desirable neutral to slightly blue hue to polyesters having a yellow appearance. The thermally stable colored compounds can have polyester reactive groups and are preferably incorporated into the polyester polymer structure during polymerization.

Abstract: The present invention provides a biaxially oriented polyester film made of a polyester containing 0.01 to 5% by weight of crosslinked polymer particles characterized by:(1) having a particle size distribution ratio (.gamma.) of 1.3 to 3.5,(2) having an average particle diameter of 0.1 to 2 .mu.m,(3) having a non-circularity of 3.4 or more, and(4) having a standard deviation of noncircularity, of at least 0.16.The polyester film of the present invention has a flat surface having a small number of large protuberances, excellent running property and excellent winding property, and can be produced economically. The film has excellent properties for use as a base for various magnetic recording media.

Abstract: Modified polyester resins contain polyester blocks which have been obtained from dicarboxylic acids and dialcohols, groupings of the formulae ##STR1## where X=Z=a hydrocarbon radical having 1 to 20 C atoms and Y=a hydrocarbon radical having 2 to 25 C atoms, and if appropriate groupings originating from crosslinking agents. They can be used as base polymers for toners.

Abstract: The present invention relates to polyesters which are particularly suitable in coating compositions which are sprayed with compressed fluids which act as viscosity reducing diluents.

Abstract: A block copolymer of generally an AB, ABA, or A(BA).sub.n structure, or mixtures thereof where the A block is an unsaturated polyester, the B block is a flexible polymer having a Tg of 0.degree. C. or lower, and n is 2 to 5. The various block components are generally first separately prepared as polymers with the flexible polymer generally having 1 or 2 functional end groups such as an amine group, a carboxyl group, or a hydroxyl group with the later being preferred. Alternatively, for low molecular weight unsaturated polyester blocks, the block can be made in situ. The preferred reaction route is to react a mono or dihydroxy terminated flexible polymer with a diisocyanate which subsequently can be readily reacted with the polyester. The block copolymers can be utilized as toughening agents.

Abstract: Stable, non-gelled, one-package coating compositions capable of being cured at ambient conditions to produce durable coatings comprising at least one polymer and/or oligomer having a molecular weight of at least about 100 and bearing at least two specific aziridine moieties, at least two specific carbodiimide moieties or combinations thereof and at least one polymer and/or oligomer having a molecular weight of at least about 100 and bearing at least two covalently blocked carboxylic acid moieties. Process for coating a substrate using such compositions are also claimed.

Abstract: A liquid crystal polyester resin composition improved in fluidity which comprises 100 parts by weight of liquid crystal polyester and 0.5-10 parts by weight of an oligomer comprising a repeating structural unit of the formula ##STR1## as the main component and having a flow temperature determined by a specified method which is in the range of 160.degree.-350.degree. C. and is at least 20.degree. C. lower than the flow temperature of the liquid crystal polyester to be combined therewith.

Abstract: Thermosetting composition is excellent in storage stability, useful as one component thermosetting composition, gives cured products having excellent chemical properties, physical properties and weathering resistance and is favorably utilized in coating compositions, ink, adhesive and molded plastics.The thermosetting composition comprises a compound having in the molecule two or more carboxyl groups blocked by a vinyl ether compound, a vinyl thioether compound or a hetero compound having a vinyl type double bond and oxygen or sulfur as the hetero atom, a compound having two or more reactive functional groups which can form a chemical bond with the blocked carboxyl compound by heating and optionally a thermal latent acid catalyst. The blocked carboxyl group of the first compound and the reactive functional group of the second compound may be comprised in the same molecule.

Abstract: The invention provides a process of manufacturing a shaped polyester article having an oxygen permeability of from about 0.2 to about 4.9 cc-mil/100 in.sup.2 -24 hr-atm at a temperature of 23.degree. C. and at 100% relative humidity inside and 60% relative humidity outside, and an enthalpy of recrystallization of from about 0 to about -2.1 cal/g, as well as a linear dimensional shrinkage between about 0% and 6% when heated from about -60.degree. C. to about 200.degree. C. The crystalline polyester articles are useful as containers for microwavable, ovenable and/or frozen foods, and have good gas barrier properties, and post-mold dimensional stability from about -60.degree. C. to about 200.degree. C.

Abstract: A thermosetting powder paint coating containing a polymeric binder comprising a polyester graft acrylic copolymer and a low molecular weight crystalline polyester. The coatings can be pigmented or non-pigmented. The polyester-graft-acrylic copolymer can be self-crosslinking by the inclusion of beta-hydroxy ester groups or crosslinked by an external crosslinker.

Abstract: This invention relates to a process for preparing copolyester fibers having reduced spinning defects. More particularly, the invention relates to fibers having improved quality prepared from blends of certain poly(ethylene terephthalate) compositions modified with 1,4-cyclohexanedimethanol by melt spinning to produce filaments with decreased spinning defects while maintaining the chemical resistance, abrasion resistance, electrical and mechanical properties normally associated with copolyesters. These polymer blends when heated provide a fiber-forming polymer melt/dope which has excellent flowability and produces high quality fiber when subjected to conventional melt spinning, drawing, texturing, etc. Staple fibers prepared from the polymer blends of the invention when made into high loft battings have excellent fiberfill performance properties, particularly resilience and compression recovery.

Abstract: Blends of a poly(ethylene terephthalate) matrix and a thermotropic liquid crystalline segmented block copolymer comprising rod (e.g., aromatic ester mesogen units containing flexible alkylene spacers) and flexible coil polymer blocks of poly(butylene terephthalate) can be used as molding compositions or in the formation of fibers and films.

Abstract: The invention provides for crystalline polyester articles of manufacture having an oxygen permeability of from about 0.2 to about 4.9 cc-mil/100 in.sup.2 -24 hr-atm at a temperature of 23.degree. C. and at 100% relative humidity inside and 60% relative humidity outside, and an enthalpy of recrystallization of from about 0 to about -2.1 cal/g, as well as a linear dimensional shrinkage between about 0% and 6% when heated from about -60.degree. C. to about 200.degree. C. These articles are useful as containers for microwavable, ovenable and/or frozen foods, and have good gas barrier properties, and post-mold dimensional stability from about -60.degree. C. to about 200.degree. C.

Abstract: This invention relates to an aqueous dispersion of a water-dissipatable polyester and a styrenated acrylic copolymer in combination with either an acrylic polymer or a hydantoin-formaldehyde resin.

Abstract: The invention provides a polyester having an oxygen permeability of from about 0.2 to about 4.9 cc-mil/100 in.sup.2 -24 hr-atm at a temperature of 23.degree. C. and at 00% relative humidity inside and 60% relative humidity outside, and an enthalpy of recrystallization of from about 0 to about -2.1 cal/g, as well as a linear dimensional shrinkage between about 0% and 6% when heated from about -60.degree. C. to about 200.degree. C. The invention also provides a process of manufacturing the above polyester, an article comprising this polyester and a process for making this article. The crystalline polyester article is useful as a container for microwavable, ovenable and/or frozen foods, and has good gas barrier properties, and post-mold dimensional stability from about -60.degree. C. to about 200.degree. C.

Abstract: Polyester compositions with a high crystallization rate obtained by mixing, at a high temperature, a polyester resin with at least one organic compound having the general formula:ROOC--Ar--OOC--Ar'--COO--Ar--COOR (I)where R represents a hydrogen atom or a C.sub.1 -C.sub.4 alkyl radical whereare Ar and Ar', either the same or different, represent a simple or condensed aromatic radical containing from 6 to 12 carbon atoms, and cooling the mixture thus obtained to room temperature.

Abstract: The present invention relates to a polymer blend composition for melt molding which is a composition obtained by adding a thickener to a polymer blend comprising a liquid crystal polymer and a non-liquid crystal polymer, characterized in that the melt viscosity of the composition determined at a molding temperature at a shear rate of 1000 sec.sup.-1 is the same or higher than the melt viscosity of said non-liquid crystal polymer determined under the same conditions.According to the present invention, a polymer blend for melt molding having improved properties, whereby problems observed in prior arts upon molding a polymer blend comprising a liquid crystal polymer and a non-liquid crystal polymer (for example, insufficient alignment of the liquid crystal polymer and difficulties in extrusion, because of excessively low melt viscosity) can be solved, is obtained.

Abstract: Macrocyclic poly(alkylene dicarboxylate) oligomers are prepared by the reaction of a dicarboxylic acid chloride such as terephthaloyl chloride with at least one bis(hydroxyalkyl) ester such as bis(4-hydroxybutyl) terephthalate, in the presence of a Lewis acid as catalyst. Illustrative Lewis acids are ferric chloride, zinc chloride, zinc bromide, stannous bromide and antimony pentachloride.

Abstract: The present invention relates to a process for the preparation of a thermoplastic resin composite comprising conducting polycondensation of a monomer material in a solution of an organic solvent containing an organic solvent soluble polymer to form an aromatic condensation polymer which is insoluble in said organic solvent and a thermoplastic resin composite prepared by the process.

Abstract: Novel blends of (i) PET, PBT, CoPET, CoPBT or mixtures thereof with (ii) nylon, wherein component (i) is from a catalyst system based on antimony and germanium, or has virtually no residual cobalt and manganese are disclosed and claimed. These blends have superior barrier properties and clarity. The clarity thereof is further enhanced by adding cobalt octoate to the blend. Articles from such blends are also disclosed and claimed. Novel blends of nylon and cobalt octoate which exhibit superior barrier properties are also disclosed and claimed, as well as articles therefrom. And, multilayer structures and articles therefrom having a core layer of a blend of (i) PET, PBT, CoPET, CoPBT or mixtures thereof, and, (ii) nylon, and optionally (iii) cobalt octoate, are also disclosed and claimed.

Abstract: A coating composition having a total solids content of at least about 85 wt. %, based on the weight of the composition, a volatile organic chemical content of less than about 15 wt. %, based on the weight of the composition and a Brookfield viscosity of about 500-2,000 centipoises at 25.degree. C. The composition contains a polyester polyol having a weight average molecular weight of about 300-900 and a hydroxy number of about 150-400; at least one thermosettable polyester; an alkoxy aminoplast resin; a reactive diluent present in an amount of 0-30 wt. %, based on the weight of the composition; and an acid catalyst curing agent.

Abstract: Compositions are provided which comprise a polyester resin which comprises the reaction product of at least one straight chain, branched, or cycloaliphatic C.sub.2 -C.sub.10 alkane diol or chemical equivalent thereof; and a cycloaliphatic diacid or chemical equivalent thereof; and a poly(ether ester) elastomer, a poly(etherimide ester) elastomer, a copolymer elastomer comprising (ether ester) monomers and (etherimide ester) monomers, a copolymer comprising ethylene and one or more comonomers copolymerizable therewith to provide a solid copolymer, or a combination of any of the foregoing. These compositions have excellent tensile properties.

Abstract: Disclosed is a resin composition for a resin-banded bearing comprising from 25 to 65% by weight of a thermoplastic polyester elastomer, from 70 to 20% by weight of a thermoplastic polyester resin, and from 5 to 15% by weight of a filler, based on the total amount of the thermoplastic polyester elastomer, the thermoplastic polyester resin and the filler. The resin composition withstands long-term use at high temperatures of 140 or higher to exert creep-proofing performance in a stable manner.

Abstract: The present invention relates to plastics that can be obtained by reacting unsaturated and/or hydroxyl-group-containing fatty acids or their esters or mixtures of various such fatty acids and esters with bifunctional ester-forming and/or amide-forming compounds and, if necessary, subsequently converting ethylenic double bonds, to give difatty acid diamides, difatty acid diesters, difatty acid amide esters, monofatty acid amide amines or monofatty acid amide alcohols as monomer components which contain at least two reactive groups suited for linkage to give polymers, in particular ethylenic double bonds, hydroxyl groups, epoxy groups or amino groups, and by linking the said compounds in the known way via a second group of bifunctional compounds that are capable of reacting with these free reactive groups to give the desired plastics.

Abstract: A modified polyester resin is the reaction product of:(A) an acid component mainly comprised of terephthalic acid, 2,6-naphthalene dicarboxylic acid or a lower alcohol ester thereof,(B) a diol component mainly comprising an alkylene glycol having 2 to 8 carbon atoms, and(C) an aromatic sulfonic acid compound of the following general formula (1):HO(RO).sub.n --Ar--SO.sub.3 M (1)where Ar represents a benzene or naphthale ring, n represents an integer from 1 to 10, R represents a group selected from among alkylenes having 2 or 3 carbon atoms and when n is 2 or more, R may be the same as or different from one another, and M represents an alkali metal selected from lithium, sodium and potassium. The modified polyester resin also satisfies the following formulas (2) and (3):0.25.ltoreq.x.ltoreq.100 (meq/kg) (2)2.ltoreq.(x/CEG).times.100.ltoreq.

Abstract: The crystallinity of polyesters prepared from macrocyclic poly(1,4-butylene terephthalate) oligomers is reduced and cracking of molded parts suppressed by the incorporation therein of at least one other linear or macrocyclic poly(alkylene dicarboxylate) oligomer, such as poly(ethylene terephthalate) or poly(1,4-butylene isophthalate). It is preferably employed in macrocyclic form. The resulting compositions can be combined with inert fillers and polymerized.

Abstract: A laminated draw-formed container obtained by draw-forming a laminated material of a metal plate on which a resin film is laminated into a cup with bottom, wherein the resin film comprises a polyester composition which contains a polyethylene terephthalate component as a chief component and further contains a polyethylene isophthalate component and a polybutylene terephthalate component, the resin film having a density of from 1.32 to 1.39 g/cc at any part of the container and further having, on the upper part of the container, a trans ratio of ethylene glycol residue of from 0.1 to 1.5 as found by the ATR method, as well as a process for producing the container. The draw-formed container exhibits excellent shock resistance irrespective of the passage of time, and particularly dent resistance and barrier property against corrosive components, as well as intimate adhesion to the metal substrate.

Abstract: Disclosed herein is a process for the production of polyester which involves heating a polymerizable monomer or oligomer in an inert liquid which does not dissolve or swell the monomer, oligomer, or polyester product, while boiling the inert liquid and codistilling the low molecular weight byproduct of the polymerization.

Abstract: This invention pertains to novel copolyesters consisting essentially of units (I), (II), (III), and (IV). ##STR1## and blends of these polymers and articles made from both. Units (I), (II), (III), and (IV) are present in specified proportions as defined in the "Description of the Invention."The instant copolyesters display orientation in the molten state, good fiber ratings and high strength; they have melting points in the range of from about 340.degree. to about 400.degree. C. and are melt-processible. Advantageously, these compositions filled with about 30 weight percent of glass fibers display heat distortion temperatures of over 240.degree. C. up to about 280.degree. C. and higher, when measured under a load of 264 psi. When blended, certain properties are improved, particularly they are easier to melt fabricate, have a decreased tendency to blister and increased strength.

Abstract: The present invention relates to a biaxially oriented polyester film comprising a metallic alkylbenzene sulfonate derivative of formula(I), polyethylene glycol and, optionally, bis(4-.beta.-hydroxyalkoxyphenyl) sulfones of formula(II), which has improved antistatic property, clarity, mechanical properties and heat resistance: ##STR1## wherein: R represents an optionally substituted C.sub.8-25 alkyl group;M represents an alkali or alkali earth metal;m is an integer of 100 or fewer; andn is an integer from 1 to 10.

Abstract: The present invention relates to a process for the manufacture of a cast, injection moulded or compression moulded articles by curing a resin composition in a desired shape using catalysts, and allowing the shaped piece to post-cure under such conditions that an HDT of at least 150.degree. C. is obtained. The resin composition comprises a polyisocyanate, an ethylenically unsaturated monomer and a vinyl ester compound, and the vinyl ester compound contains on average about two to about 6 (meth)acrylate groups and on average about two to about 6 hydroxyl groups, and has a molecular weight higher than 300. The invention also relates to a resin composition suitable for use in the process.

Abstract: Disclosed is a polymer blend having excellent clarity and impact strength which is suitable for use in extrusion blow molding processes comprisinga) about 50-95 wt % of a polyester having repeat units from at least 95 mol % terephthalic acid, at least 90 mol % ethylene glycol and up to 10 mol % 1,4-cyclohexanedimethanol, the polyester having a weight average molecular weight of 75,000-85,000,b) about 40-4 wt % of recycled scrap polyester having repeat units from at least 90 mol % terephthalic acid and at least 90 mol % ethylene glycol and having a molecular weight of about 40,000-55,000, andc) about 1-10 wt % of a polymeric material containing at least 90 wt % polycarbonate and up to 10 wt % polyethylene terephthalate.

Abstract: A biaxially oriented polyester film simultaneously satisfying the following formulas (I) to (III):.vertline.S.sub.180 -S.sub.120 .vertline..ltoreq.54 (I)T.sub.S.sup.MD .gtoreq.100 (II)Q.sub.120 .ltoreq.0.7 (III)wherein S.sub.180 is shrinking stress (g/mm.sup.2) of the film in the machine direction at 180.degree. C., S.sub.120 is shrinking stress (g/mm.sup.2) of the film in the machine direction at 120.degree. C., T.sub.S.sup.MD is shrinkage initiation temperature (.degree.C.) of the film in the machine direction, and Q.sub.120 is shrinkage (%) of the film in the machine direction after 5 hours' treatment at 120.degree. C., is described. The film has a good dimensional stability due to its low shrinkage, particularly in the machine direction, and substantially free from defect such as wave and wrinkle.It is prepared by biaxially stretching, heat-setting and relaxing an extruded polyester film under particular conditions so as to obtain a biaxially oriented polyester film having these characteristics.