Document gb67R8zp8yra8LyDO4e2aE7Za

United States Patent [19] Hochberg et al. [li] Patent Number: 4,900,610 [45] Date of Patent: Feb. 13, 1990 [54] POLYESTER MOLDING COMPOSITION [75] Inventors: Arie A. Hochberg, Montclair; Varkki P. Chacko, Summit; Paul DeStio, Bound Brook, all of N.J. [73] Assignee: Hoechst Celanese Corporation, Somerville, N.J. [21] Appl. No.: 157,951 [22] Filed: Feb. 19,1988 [51] IntCl.*............................................ C08L 67/02 [52] U.S. a.......................................... 428/195; 524/449; 524/513; 524/539; 525/64; 525/176; 525/444 [58] Field of Search ........................ 525/444, 176, 64; 428/195; 524/449, 513, 539 [56] References Cited U.S. PATENT DOCUMENTS 3,578,729 4,096,202 4,125,571 4,349,503 5/1971 Brinkmann .......................... 525/176 6/1978 Farnham .............................. 523/201 11/1978 Scott ...................................... 525/444 9/1982 Aharoni ......................... 264/328.16 4,465,728 8/1984 Haigh et al............................ 428/156 4,587,155 5/1986 Durand ................................. 428/195 OTHER PUBLICATIONS "Hot Stamping Shows a World of Versatility", Modem Plastics, Dec. 1985. Primary Examiner--Patricia Short Attorney, Agent, or Firm--Depaoli & O'Brien [57] ABSTRACT A thermoplastic molding composition comprising a polyester blend of polybutylene terephthalate and a copolyester derived from condensing ethylene glycol, cyclohexanedimethanol and terephthalic acid wherein the ethylene glycol units of the copolyester comprises at least 25 mole % based on the total glycol content. The polyester blend can also include an impact modi fier. The blend is useful in the formation of molded keycaps. 19 Claims, No Drawings 4,900,610 12 acid, isophthalic acid and bisphenol A and a polyester POLYESTER MOLDING COMPOSITION derived from terephthalic acid, ethylene glycol and 1,4-cyclohexanedimethanol. This invention is concerned with thermoplastic poly U.S. Pat. No. 4,582,876 discloses a molding composi ester compositions. More particularly, it relates to a 5 tion having high impact which comprises a blend of a molding composition comprising a blend of a poly( 1,4- copolyester formed from terephthalic acid, 1,4- butylene terephthalate) and a copolyester resin of poly cyclohexanedimethanol and ethylene glycol and a rub ethylene cyclohexanedimethylene terephthalate). ber-modified styrene-maleic anhydride copolymer. BACKGROUND OF THE INVENTION 10 SUMMARY OF THE INVENTION Poly(1,4-butylene terephthalate) resins are well know It has been found that the addition of a copolyester and have been widely employed for the production of resin derived from ethylene glycol, cyclohexanedime thermoplastic molded articles. Also, reinforced compo thanol and terephthalic acid to poly( 1,4-butylene tere sitions of poly(1,4-butylene terephthalate) have been phthalate) (PBT) resin reduces the shrinkage of the commercially available for a number of years. Unfilled 15 PBT while increasing the deflection temperature under poly( 1,4-butylene terephthalate) has good processabil load. Additionally, if the copolyester resin derived from ity, strength and toughness. Other key properties in ethylene glycol, cyclohexanedimethanol and tereph clude low water absorption resulting in good dimen thalic acid is added to a reinforced poly(1,4-butylene sional stability, low static and dynamic coefficients of terephthalate) molding composition, the molded arti friction, good chemical and abrasion resistance, and 20 cles are substantially resistant to warpage or distortion good electrical properties. However, the unfilled po after they are removed from the mold. This result is ly(1,4-butylene terephthalate) has a relatively low heat achieved without any appreciable decrease in mechani deflection temperature which limits its use. Also, un cal, physical or molding properties of a typical glass filled poly( 1,4-butylene terephthalate) has a tendency to reinforced poly( 1,4-butylene terephthalate) molding shrink to a great extent after being molded. 25 composition. Reinforced poly( 1,4-butylene terephthalate) and, par Moreover, it has been found that the addition of mul ticularly, glass reinforced poly( 1,4-butylene terephthal tiphase ABS and MBS impact modifiers to the polyester ate) has additionally increased tensile strength over the blend improve impact strength without adversely af unfilled poly( 1,4-butylene terephthalate). However, fecting the improved warpage properties. Polyethy when molded, reinforced, particularly glass reinforced 30 lene ethylacrylate) impact modifier has also been found poly(1,4-butylene terephthalate) has a tendency to be to improve the impact strength of the polyester blend at come distorted or warped. low levels of addition. U.S. Pat. No. 4,125,571 discloses a thermoplastic composition comprising a combination of poly (1,4- DETAILED DESCRIPTION OF THE butylene terephthalate) and a polyester resin derived 35 INVENTION from cyclohexanedimethanol and a hexacarbocyclic According to this invention, there is provided a ther dicarboxylic acid such as terephthalic acid. It was found moplastic composition comprising a blend of poly( 1,4- that the shrinkage of poly (1,4-butylene terephthalate) butylene terephthalate) resin and a copolyester resin resin was reduced while increasing the heat deflection derived from ethylene glycol, cyclohexanedimethanol, temperature. Reinforced polybutylene terephthalate 40 and terephthalic acid. molding compositions had increased resistance to war- A preferred feature of this invention is to provide page or distortion upon removal from the mold upon reinforced thermoplastic compositions comprising po- adding the polyester resin derived from cyclohex ly(l,4-butylene terephthalate) resin, a copolyester resin anedimethanol. The patent broadly states that cy derived from ethylene glycol, cyclohexanedimethanol, clohexanedimethanol and minor amounts of other bi 45 and terephthalic acid, and a reinforcing amount of a functional alcohols can be condensed with the dicar boxylic acid. Examples of such bifunctional glycols reinforcing filler. The high molecular weight, polymeric 1,4-butylene include ethylene glycol, butylene glycol, etc. However, glycol terephthalate has repeating units of the general the patent does not describe any minimum or maximum for the minor amounts of other bifunctional glycols to 50 formula: be included in the polyester resin. The examples in this U.S. patent are directed to a poiy(l,4-cyclohexanedime- thanol terephthalate-co-isodialate) resin which is sold under the trade name of KODAR A150, from Eastman Chemical Products. 55 U.S. Pat. No. 4,225,688 discloses a copolyester com position which exhibits good bonding characteristics to Also contemplated are mixtures of the ester with minor polyvinylchloride plastics, consisting essentially of: amounts, e.g., from 0.5 to 2% by weight, of units de from 80-95% by weight of a rigid polyethylene cy rived from aliphatic or aromatic dicarboxylic acids clohexanedimethylene terephthalate) such as exempli 60 and/or aliphatic polyols, e.g., glycols, i.e., copolyesters. fied by the commercial product KODAR PETG 6763; These can be made by following the teachings outlined and 5-20% by weight of a flexible copolymer contain in Whinfield et al, U.S. Pat. No. 2,465,316 and Pengilly, ing alternating blocks of poly(butylene terephthalate) U.S. Pat. No. 3,047,539, for example. Among the units and poly (1,4 butylene oxide) as exemplified by Hytrel a which can be present in the copolyesters are those de commercial product from the E.I. Dupont de Nemours 65 rived from aliphatic dicarboxylic acids, e.g., of up to and Company. about 50 carbon atoms, including straight and branched U.S. Pat. No. 4,287,325 discloses a polyester blend chain acids, such as adipic acid, dimerized- Ci6-Cis comprising a copolyester formed from terephthalic unsaturated acids (which have 32 to 36 carbon atoms), 4,900,610 34 trimerized such acids, and the like. Among the units in metals, such as carbon filaments, silicates, such as mica, the copolyesters can also be minor amounts derived aluminum silicate (clay), talc, asbestos, titanium dioxide, from aromatic dicarboxylic acids, e.g., of up to about 36 Wollastonite, Novaculite, potassium titanate and tita- carbon atoms, such as isophthalic acids and the like. In nate whiskers, glass flakes, glass beads and fibers and addition to the 1,4-butylene glycol units, there can also 5 polymeric fibers and combinations thereof. be minor amounts of units derived from other aliphatic Although it is only necessary to use a reinforcing glycols and polyols, e.g., of up to about 50 carbon amount of the reinforcing agent, from 1-60 parts by atoms, including ethylene glycol, propylene glycol , weight of the total weight of the composition may com glycerol and the like. Such copolyesters can be made by prise the reinforcing agent. A preferred range is from techniques well known to those skilled in the art. Po- 10 5-50 parts by weight. ly(l,4-butylene terephthalate) homopolymer is the pre The preferred reinforcing agents are of glass, and it is ferred polyester and is commercially available. preferred to use fibrous glass filaments, mixtures of glass These polymeric 1,4-butylene glycol terephthalates and talc, glass and mica, glass and aluminum silicate, have an intrinsic viscosity of at least 0.4 and preferably and glass fibers and glass beads, for example, to improve at least about 0.7 deciliters/gram as measured in o- 15 both shrinkage and warpage of the molded products. chlorophenol, a 60/40 phenol tetrachloroethane mix An impact modifier which can be used effectively in ture or a similar solvent at 25-30" C. The upper limit is the polyester blend of this invention is a multiphase not critical, but it will generally be about 5.0 dl./g. composite interpolymer comprising 25 to 95 weight Especially preferred PBT polyesters will have an intrin percent of a first elastomeric phase and 75 to 5 weight sic viscosity in the range of about 0.7 to 2.0. 20 percent of a final rigid thermoplastic phase. One or The copolyesters for use in the blend with PBT are more intermediate phases are optional, e.g., a middle prepared by condensing ethylene glycol, and either the stage polymerized from 75 to 100 percent by weight of cis- or trans-isomer (or a mixture thereof) of 1,4- styrene may be incorporated. cyclohexanedimethanol with terephthalic acid. The The first stage is polymerized utilizing 75 to 99.8 amount of the ethylene glycol component present in the 25 weight percent Ct to Cs alkyl acrylate, generally result copolyester can vary widely, but it is preferred that the ing in an acrylic rubber core having a Tg below 10' C., ethylene glycol component be present in amounts of at and cross-linked with 0.1 to 5 weight percent cross-link least about 25 mole percent relative to the total glycol ing monomer and further containing 0.1 to 5 weight residues. More preferably, the glycol component of the percent graftlinking monomer. The preferred alkyl ac copolyester will comprise 30-70 mole percent ethylene 30 rylate is butyl acrylate. glycol and 70-30 mole percent cyclohexanedimethanol. The cross-linking monomer is a polyethylenically It is preferred that the copolyester include terephthalic unsaturated monomer having a plurality of additional acid as the sole acid residue of the copolyester. polymerizable reactive groups, all of which polymerize The copolyesters of this invention are available as at substantially the same rate of reaction. Suitable cross- commercial products. Thus, copolyester materials 35 linking monomers include polyacrylic and methacrylic known as poly(ethylene cyclohexanedimethylene tere esters of polyols such as butylene diacrylate and butyl phthalate) are sold by the Eastman Kodak Company, ene dimethacrylate, trimethylolpropane trimethacrylate for example, under the trademarks Kodar PCTG 5445 and the like; di- and trivinyl benzene, vinyl and the like. and Kodar PETG 6763. Kodar PCTG 5445 is believed The preferred cross-linking monomer is butylene diac to be a polyester based on cyclohexanedimethylene 40 rylate. terephthalate modified with approximately 30 mole The graftlinking monomer is a polyethylenically un percent ethylene glycol relative to the total glycol com saturated monomer having a plurality of additional ponent of the copolyester. Kodar PETG 6763 is a co polymerizable reactive groups, at least one of the reac polyester of polyethylene terephthalate, modified with tive groups polymerizing at a substantially different rate cyclohexanedimethanol also sold by the Eastman 45 of polymerization from at least one other of said reac Kodak Company and having approximately 70 mole tive groups. The function of the graftlinking monomer percent of ethylene glycol units relative to the total is to provide a residual level of unsaturation in the elas glycol component. tomeric phase, particularly in the latter stages of poly These copolyesters should have an intrinsic viscosity merization and, consequently, at or near the surface of between 0.40 and 2.0 dl/g measured in a 60/40 phenol- 50 the elastomeric particles. When the rigid thermoplastic tetrachloroethane solution or a similar solvent at phase is subsequently polymerized at the surface of the 25-30 C. Especially preferred polyesters will have an elastomer, the residual unsaturated additional polymer intrinsic viscosity in the range of 0.6 and 1.2 dl/g. izable reactive groups contribute by the graftlinking The poly( 1,4-butylene terephthalate) resin and the monomer participate in the subsequent reaction so that copolyester resin derived from ethylene glycol and 55 at least a portion of the rigid phase is chemically at cyclohexanedimethanol are combinable with each other tached to the surface of the elastomer. Among the effec in all proportions, such as 1 to 99 parts by weight of tive graftlinking monomers are allyl groups containing poly(1,4-butylene terephthalate and 99 to 1 parts by monomers such as allyl esters of ethylenically unsatu weight of the polyester. In general, however, blend rated acids, e.g. allyl acrylate, allyl methacrylate, diallyl compositions containing from about 50 to about 90 parts 60 maleate, diallyl fumarate, diallyl itaconate, allyl acid by weight of poly( 1,4-butylene terephthalate) and from maleate, allyl acid fumarate and allyl acid itaconate. about 10 to 50 parts by weight of the copolyester are Somewhat less preferred are the diallyl esters of poly- preferred. Especially preferred are blends comprising carboxylic acids which do not contain polymerizable 70 to 85% by weight polybutylene terephthalate and 15 unsaturation. The preferred graftlinking monomers are to 30% by weight of the copolyester. 65 allyl methacrylate and diallyl maleate. Reinforcing agents my be included in the polyester The final stage can be polymerized from a monomer blend and can be selected from finely divided alumi system comprising Ci to Ci6 alkyl methacrylate, sty num, iron or nickel and the like, metal oxides, and non rene, acrylonitrile, alkyl acrylates, allyl methacrylate, 4,900,610 56 diallyl methacrylate and the like, as long as the overall ters and numerals onto the surface of the keycaps. Im Tg is at least 20 C. Preferably the final stage monomer portantly, the polyester blend of this invention can also system is at least 50 weight percent of a Ci to C4 alkyl be molded in the same equipment as the ABS molding acrylate. resin and, thus, the use of the polyester blend does not A most preferred interpolymer has only two stages. 5 require retooling. The first stage, about 60 to 95 weight percent of the interpolymer, is polymerized from a monomer system EXAMPLE 1 comprising 95 to 99.8 weight percent butyl acrylate, 0.1 In this example, variable amounts of polybutylene to 2.5 weight percent butylene diacrylate as the cross- terephthalate and a copolyester of poly(ethylene cy- linking agent and 0.1 to 2.5 weight percent allyl methac- 10 clohexanedimethylene terephthalate) are compounded rylate or diallyl maleate as the graftlinking monomer. with and without an impact modifier in order to assess The final stage of the interpolymer is polymerized from the impact strength of the polyester blend. 5 to 40 weight percent methyl methacrylate. The following ingredients are dried: The most preferred multiphase composite interpoly polybutylene terephthalate, intrinsic viscosity, 1.2 mer is commercially available from Rohm and Haas and 15 dl/g, GAFITE 1600A, GAF Co.; is designated as Acryloid KM-330 TM. poly(ethylene, 1,4-cyclohexanedimethylene tere Another useful impact modifier for use in the polyes phthalate), KODAR PCTG 5445, Eastman Chemi ter blend of this invention is polyethylene ethylacry- cal Products; late) (PEEA). The impact modifier is a copolymer com polycarbonate. Calibre 300-3, Dow Chemical; prising 70 to 90 mole percent ethylene units and 10 to 30 20 MBS impact modifier, Paraloid 8407 XP, Rohm and mole percent recurring ethylacrylate units. A preferred Haas Co. impact modifier will have 80 to 90 mole percent ethyl The blends are compounded in an extruder at about ene and 10 to 20 mole percent ethylacrylate. 540 F. The extrudate is pelletized and the pellets are The impact modifier, if used in the polyester blend, injection molded at 500 F, mold temperature 100 F, will generally comprise from about 2 to about 30 weight 25 into ASTM type test bars in a standard machine. The percent based on the total weight of the composition. It test bars are tested for impact strength, ASTM D-256. has been found, however, that when using PEEA, The formulations and room temperature notched Izod amounts of 2-10 wt.% are useful, preferably about 5 strength are set forth in Table 1. TABLE 1 Ingredients wt. % 1. PBT 2. PCTG 5445 3. MBS impact modifier 4. Polycarbonate RT Notched IZOD (ft-lb/in) Unfilled Polyester Blend ABCDE FGH I 85 so 50 80 75 70 75 70 65 50 5 10 15 5 10 15 15 20 15 15 15 20 20 20 J 50 50 16.8 18.7 0.78 18.5 19.2 20.3 20.7 20.1 21.11 1.11 wt.%, while the multiphase "Acryloid" modifiers usu ally require more than 10 wt.% to improve impact of 40 It can be seen that the polyester blends of the present the blend. invention have greatly enhanced impact strength upon The polyester blend composition may be prepared by the addition of the MBS impact modifier to the blend. conventional techniques. One convenient method com Sample C which includes a polyester blend without the prises blending the polyesters in powder or granular additional impact modifier has an impact strength simi form, extruding the blend and comminuting into pellets 45 lar to the unfilled polybutylene terephthalate which has or other suitable shapes. a room temperature notched Izod of about 1.0 ft-lb/in. The reinforcements are added in any usual manner, Sample C also has only a slightly reduced notched Izod i.e, by dry blending or mixing or by mixing in the strength relative to a blend of PBT and polycarbonate melted state in an extruder, or a heated mill or in other (Sample J). mixers. 50 Obviously, other materials can also be employed with EXAMPLE 2 the composition of this invention and include such ma The following ingredients are dried: terials as anti-static agents, pigments, mold release polybutylene terephthalate, intrinsic viscosity 1.0 agents, thermal stabilizers, flame retardants, impact dl/g, Celanex, Hoechst Celanese Co.; modifiers, extenders, UV stabilizers and the like. 55 poly(ethylene 1,4-cyclohexanedimethylene tere The polyester blends of the present invention have phthalate), KODAR PETG-6763, Eastman Chem particular use as molding compositions in the formation ical Products; of keycaps such as used in word processing and com polycarbonate, Merlon M-40, Mobay Chemical puting equipment. It has been found that the polyester Corp.; blend of the present invention has comparable impact 60 ABS impact modifier, Acryloid KM-330, Rohm and strength and shrinkage to ABS resins which are typi Haas Co.; cally used for molding keycaps. Additionally, the poly fibrous glass reinforcement. ester blend of this invention has improved solvent resis The compositions of the above ingredients are ex tance and fatigue characteristics relative to existing truded and molded into standard test bars by the proce ABS materials and as well is able to be printed by subli- 65 dure of Example 1 except that the mold temperature mation printing which allows the keycaps to be molded used is about 160 F. The test bars are tested for the in one step as opposed to the previous step of molding following physical properties: tensile strength, ASTM the keycaps and subsequently molding the printed let- D-1708; flexural strength and flexural modulus, ASTM 4,900,610 78 D-790; impact strength, ASTM D-256 and warpage. polyethylene sodium acrylate) copolymer ionomer, Warpage is measured in mils on a disk four inches in Surlyn 8550, Dupont; diameter by 1/16 inch thick as molded. The formula poly(ethylene zinc acrylate) copolymer ionomer, tions and the physical properties are set forth in Table 2. Surlyn 9020, Dupont. 5 The compositions are extruded and molded into stan- TABLE 2 Glass Reinforced Polyester Blends A BC D E F Formulation PBT Fiberglass Lubricant ABS impact modifier Polycarbonate Kodar PETG-6763 Properties Tensile Strength (psi) Flex. Strength (psi) Flex. Modulus (psi) X 10s Notched Izod (fl-lb/in) Unnotched izod (ft-lb/in) Warpage (mil) 4" X 1/16" disk 71.5 10.0 0.3 10.0 ~ -- 9,100 14,800 5.0 1.4 9.8 190 59.7 10.0 0.3 10.0 20.0 -- 9,400 15,400 5.3 1.4 8.7 90 59.7 10.0 0.3 10.0 -- 20.0 9,400 14,500 5.0 1.5 10.5 110 71.5 18.0 0.5 10.0 -- -- 12,000 18,700 7.4 1.8 n.i 240 59.7 18.0 0.5 10.0 20.0 -- 12,700 19,600 7.3 2.0 12.5 60 59.7 18.0 0.5 10.0 -- 20.0 11,800 18.400 7.2 1.8 12.0 100 In comparing Samples A and D in Table 2, it can be seen that increasing the fiberglass content of the blend, results in substantially increased warpage of the test sample. On the other hand, by comparing Samples C and F which are directed to polyester blends in accor dance with the present invention, the increased amount of glass reinforcement does not have an negative effect dard test bars by the procedure of Example 2. The test bars are tested for the physical properties as in Example 2 with the addition that the warpage of the test disc is measured along the disc axis parallel to the flow of the blend in the mold as well as transverse to the flow direc tion in the mold. The formulations and physical proper ties are set forth in Table 3. TABLE 3 A BCD EF G Formulation PBT Fiberglass Lubricant ABS impact modifier Polycarbonate PETG-6763 Poly(eihylene ethylarylate) Polyethylene acrylic acid) Polyethylene Na acrylate) Polyethylene Zn acrylate) Properties Warpage with flow (mils) Transverse to flow (mils) Tensile strength (psi) Elongation Flexural strength (psi) Flexural Modulus (psi) Notched Izod (ft-lb/in) Unnotched Izod (ft-lb/in) 59.5 18.0 0.5 10.0 12.0 214 109 11,194 2.8 17.212 7.3 2.03 11.5 59.7 10.0 0.3 10.0 20.0 141 63.6 9.796 4.1 15.974 5.3 1.85 IU 59.7 10.0 0.3 10.0 20.0 157 73.2 8,950 3.8 14.118 4.9 1.72 10.9 69.7 10.0 0.3 10.0 10.0 238 113 7,771 4.2 12,069 4.4 1.80 11.0 69.7 10.0 0.3 10.0 10.0 349 154 6,540 3.7 10.034 4.2 1.21 8.0 69.7 10.0 0.3 10.0 10.0 383 146 6.538 5.2 10.754 4.4 1.23 10.3 69.7 10.0 0.3 10.0 10.0 310 124 7.006 4.0 11.065 4.2 l.n 9.1 on warpage. Thus, it can be seen that the polyester From Table 3, it can be seen that the composition blend of the present invention acts in a similar manner blend of the instant invention (Sample C) produces a to a PBT and polycarbonate blend, Samples B and E. molded article of improved warpage relative to the EXAMPLE 3 55 blend of PBT and amorphous poly(ethylene acrylate) copolymers. The invention blend produces molded The following ingredients are dried: articles having similar warpage and physical properties polybutylene terephthalate, intrinsic viscosity, 1.0 as the article from the PBT and polycarbonate blend dl/g, Celanex, Hoechst Celanese; (Sample B). fiberglass; ABS impact modifier as in Example 2; 60 EXAMPLE 4 polycarbonate as in Example 2; Polybutylene terephthalate, fiberglass, lubricant, poly(ethylene 1,4 cyclohexanedimethylene tere ABS impact modifier, polycarbonate, PETG-6763 and phthalate) as in Example 2; polyethylene ethylacrylate) all as in Example 3 are polyethylene ethylacrylate) copolymer,DPDA- 65 dried, compounded and molded into standard test bars 6182, Union Carbide; as in Example 2. The physical properties are measured polyethylene acrylic acid) copolymer, Primacor 3330, Dow Chemical; as in the previous examples with the addition of heat deflection temperature under load, ASTM D-648. The 4,900,610 formulations and physical properties are set forth in Table 4. 10 EXAMPLE 6 TABLE 4 PBT Fiberglass Lubricant ABS impact modifier Polycarbonate PETG-6763 Poly(ethylene ethylacrylate) Properties Warpage with flow (mils) Tensile strength Cpsi) % Elongation Flexural strength Flexural modulus X 10s (psi) Notched Izod (ft-lb/in) Unnotched Izod (ft-lb/in) Physical Density HDT 'C. at 264 psi B CDE FG H 59.5 59.5 54.5 64.5 59.7 59.7 49.7 18.0 18.0 18.0 18.0 10.0 10.0 10.0 0.5 0.5 0.5 0.5 0.3 0.3 0.3 59.7 10.0 0.3 10.0 10.0 10.0 10.0 10.0 10.0 _ 12.0 20.0 12.0 12.0 12.0 20.0 20.0 20.0 5.0 5.0 10.0 10.0 62 40 98 10 40 10 170 10 86 20 112 10 115 30 142 10 12,655 3.2 19,612 11,787 3.0 18,453 10,741 3.4 16,666 12,589 2.95 19,581 9,386 4.1 15,410 9,397 3.7 14,529 7,979 4.0 12,419 9,358 3.5 14,611 7.3 7.2 6.5 7.5 5.3 5.0 4.3 4.8 1.95 1.82 2.07 1.6 1.4 1.5 1.7 1.3 12.5 12.0 11.8 11.6 8.7 10.5 10.3 1.381 1.396 1.366 1.388 1.338 1.336 1.282 160 164 152 170 110 87 83 10.0 1.308 97 As can be seen from Table 4, Sample D which does Polybutylene terephthalate and Kodar PCTG-5445 not include the ABS impact modifier but only includes are blended using the ingredients as set forth in Example the 5 wt.% poly(ethyIene ethylacrylate) still has im 5 and the compositions are molded into standard test proved impact strength relative to a glass filled PBT 30 bars as previously described. Table 6 illustrates the composition. formulations and the physical properties of the blends. EXAMPLE 5 Polybutylene terephthalate having an intrinsic vis cosity of 0.7 dl/g, Celanex, Hoechst Celanese, KODAR 35 copolyesters from Eastman Chemical Products and the poly(ethylene ethylacrylate) used in Example 3 are formulated and molded into standard test bars as in the previous examples and are tested as before. In addition, shrinkage, which is measured on a i inch X 4 inch 40 diameter disk is measured in mils per inch. The formula tion and properties are shown in Table 5. TABLE 6 Formulation A PBT PCTG-5445 Polyethylene ethylacrylate) Lubricant Properties Shrinkage with flow (mil/in) Transverse to flow (mil/in) Tensile strength (psi) % Elongation Notched Izod (ft-lb/in) Flex Strength (psi) 74.7 20.0 5.0 0.3 13.0 4.0 7.370 10 0.88 10,500 B 64.7 30.0 5.0 0.3 10.2 2.0 6,920 15 0.86 9,690 c 99.7 0.3 16.9 9.0 3,090 19 0.60 11,990 TABLE 5 Formulation PBT KODAR PETG-6763 Polyethylene ethylacrylate) Lubricant KODAR PCTG 5445 Properties Shrinkage with flow (mils/in) Transverse to flow (mils/in) Tensile strength yield (psi) Tensile strength break (psi) Elongation Flex Strength (psi) Flex Mod. x 105 (psi) Notched Izod (ft-lb/in) A B C D EF G H I 99.7 89.7 79.7 69.7 59.7 49.7 84.7 74.7 89.7 10.0 20.0 30.0 40.0 50.0 10.0 20.0 5.0 5.0 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 10.0 J 69.7 0.3 30.0 19.7 18.7 15.7 11.5 17.4 15.3 16.5 7.7 14.5 13.1 10.5 5.2 E and F 12.1 5.0 5.4 2.0 8,360 8,450 8,470 8,200 Could not 7,180 7,200 8,090 7,620 be molded 8,750 7.720 7,300 6,100 6.7 17 29 85 6,250 4,630 6,160 6,010 16 18 11 8.4 12,100 12,800 12,400 11,900 10,820 10,100 11.900 11,200 3.5 3.7 3.5 3.3 3.1 3.1 3.4 3.0 0.55 0.58 0.66 0.75 0.76 0.78 0.71 2.80 4,900,610 11 12 TABLE 6-continued TABLE 8-continued Formulation AB C Material AB Flex Mod. X 105 (psi) HDT 'C. at 264 psi Density 2.87 53 1.298 2.65 51 1.298 3-44 50 1.310 As can be seen from Table 6, the polyester blends of Shrinkage (mil/in) Warpage (mils) 66 13.0 10.0 'CP 2530 Beads. 65-70 microns average diameter. Potters Industries 'Si-800. Eagle Quality Products. U^chland. Pa. 'CT 930 A4. Certan-Tecd Corp.. Valley Forge. Pa. the present invention have substantially reduced shrink As can be seen from Table 8, both shrinkage and age relative to a control polybutylene terephthalate jo warpage are good with the test samples and comparable sample. to ABS resin which has a shrinkage of 6 mils per inch EXAMPLE 7 and a warpage of about 3.5 mils. The PBT resin samples can be printed by sublimation printing techniques while Polybutylene terephthalate and Kodar blends are ABS samples cannot be so printed. formulated and molded into standard test bars as in 15 What is claimed is: Examples 5 and 6. Table 7 sets forth both the formula 1. A composition comprising a polyester blend of 50 tions and physical properties including shrinkage rela to 90% by weight of said blend of polybutylene tere tive to a control butylene terephthalate sample. phthalate consisting essentially of recurring 1,4-buty- TABLE 7 Control A BC D EF Formulation PBT KODAR PETG-6763 KODAR PCTG-5445 Polyethylene ethylacrylaie) Fiberglass Lubricant Properties Shrinkage with flow (mil/in) Transverse to flow (mile/in) Tensile strength yield (psi) Tensile Strength break (psi) % Elongation Rex strength (psi) Rex Mod. X IQ5 (psi) Notched Izod (ft-lb/in) HDT `C. at 264 psi Density 99.7 0.3 16.6 7.9 7,621 4,505 11.2 12,790 3.7 0.57 56 1.310 69.7 30.0 0.3 12.7 9.5 7,966 8,011 3.5 12,873 3.5 0.59 57 1.300 64.7 30.0 5.0 0.3 12.2 9.7 6.742 3,935 3.4 11.356 3.2 0.59 55 1.28 74.7 15.0 10.0 0.3 3.3 10.9 10,910 2.3 18,750 5.9 0.65 151 1.368 69.7 15.0 5.0 10.0 0.3 3.1 12.1 11,224 3.0 17,610 5.5 0.73 152 1.348 69.7 74.7 15.0 15.0 5.0 10.0 10.0 0.3 0.3 3.0 3.4 11.3 10.3 10,938 3.3 17.484 5.4 0.80 155 1.342 10.650 2.2 18.030 5.5 0.65 144 1.360 As can be seen from Table 7, Samples C-F have greatly reduced shrinkage relative to the PBT control. lene terephthalate units, and 10 to 50% by weight of said blend of a copolyester consisting essentially of This shrinkage is comparable used to mold keycaps. to ABS resin which is 45 condensed units of ethylene glycol, cyclohexane dime thanol and terephthalic acid, said copolyester contain EXAMPLE 8 ing about 70 mol% of said ethylene glycol units relative In this example, PBT and Kodar blends are formu lated and molded into standard test bars as in Examples 5-7. The compositions are filled with a fiberglass/glass bead and fiberglass/mica combined filler to improve 50 to the total glycol content. 2. The composition of claim 1 wherein said blend comprises about 70 to 85% by weight polybutylene terephthalate and about 15 to 30% by weight of said copolyester. shrinkage and warpage of test samples. The formula tions and properties are set forth in Table 8. 3. The composition of claim 1 further including an impact modifier. TABLE 8 55 4. The composition of claim 3 wherein said impact Material PBT KODAR PETG-6763 Poly(ethylene acrylate) Lubricant Glass Beads1 Mica* Fiberglass-* Properties AB 60.7 60.7 10.0 10.0 5.0 5.0 0.3 0.3 7.5 7.5 7.5 7.5 modifier comprises about 2 to about 30 wt.% based on the total weight of the composition. 5. The composition of claim 3 wherein said impact modifier comprises a multiphase interpolymer compris ing: (i) from 25 to 95 percent, by weight based on the total weight of the interpolymer, of a first elastomeric phase polymerized from a monomer system com Tensile Strength (psi) % Elong Rex Strength (psi) Rex Mod (psi) HDT 'F. Notched Izod (ft-lb/in) 8.660 3 14.900 530.000 25S 0.7 9.160 3 15.500 580.000 232 0.6 prising from 75 to 99.8 percent by weight, based on the first elastomeric phase, of a C\ to C$ alkyl acry late, from 0.1 to 5 percent by weight of a cross-link ing monomer, which is polyethylenically unsatu rated monomer, with a plurality of addition poly- 4,900,610 13 14 merizable reactive groups of from 0.1 to 5 percent 11. A key cap molded from the composition of claim by weight of a graft-linking monomer having a 1. plurality of addition polymerizable reactive 12. The key cap of claim 11 wherein said key cap is groups; and printed with indicia. (ii) from 75 to 5 percent by weight, based on the total 5 13. The key cap of claim 12 wherein said indicia is weight of the interpolymer, of a final rigid thermo provided by sublimation printing. plastic phase polymerized in the presence of the elastomeric phase. 6. The composition of claim 5 wherein said impact 10 14. The key cap. of claim 11 including a reinforcing filler. 15. The key cap of claim 14 wherein said reinforcing filler comprises glass fiber. modifier is present in amounts of from about 10 to 30 16. The key cap of claim 14 wherein said reinforcing wt.% based on the weight of the composition. filler comprises a mixture of glass fibers and glass beads. 7. The composition of claim 1 further including a 17. The key cap of claim 14 wherein said reinforcing reinforcing amount of a reinforcing filler. filler comprises a mixture of glass fibers and mica. 8. The composition of claim 7 wherein said reinforc 15 18. The key cap of claim 11 including an impact mod ing filler comprises glass. ifier. 9. The composition of claim 8 wherein said glass 19. The key cap of claim 18 wherein said impact comprises glass fibers. modifier is present in amounts of from about 10 to 30 10. The composition of claim flame retardant. 1 further including a 20 wt.% based on the w*ei*ght*of*th*e composition. 25 30 35 40 45 50 55 60 65