CA1166781A - Process for injection molding a rapidly crystallizing polyethylene terephthalate composition at reduced mold temperatures - Google Patents
Process for injection molding a rapidly crystallizing polyethylene terephthalate composition at reduced mold temperaturesInfo
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- CA1166781A CA1166781A CA000363909A CA363909A CA1166781A CA 1166781 A CA1166781 A CA 1166781A CA 000363909 A CA000363909 A CA 000363909A CA 363909 A CA363909 A CA 363909A CA 1166781 A CA1166781 A CA 1166781A
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
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- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Injection Moulding Of Plastics Or The Like (AREA)
Abstract
This disclosure is concerned with a process for molding polyethylene terephthalate at a reduced mold temperature, i,e. less than 120.degree.C, and still obtaining crystalline parts by incorporating a small amount of a two-phase polyacrylate comprised of a cross-linked elastomeric first phase to which a rigid thermoplastic second phase has been grafted. It is also concerned with a glass reinforced polyethylene terephthalate especially suitable for molding into colder molds which contain this two-phase polyacrylate.
Description
-781 M~-2039-Ca PC-52~ Ca PROC~SS FOR INJ~CTION MOJ,DING A RAPID~Y
CRYSTALLIZING POLYETHYLENE TE.,REPHTHALATE
COMPOSITION AT REDUCED MOIJD TEMPERATURES
BACKGROUND OF THE INVENTION
Polyalkylene terephthalates have acquired con-siderable significance as starting materials ~or the pro duction of fibers, films and shaped articles. By virtue of their partially crystalline structure, they show outstanding properties, for example, high wear resistance, favorable creep rupture strength and high dimensional stability~ and are therefore particularly suitable for the production of shaped articles subjected to heavy mechanical and thermal stressing. An additional improvement in their mechanical properties can be obtained by the incorporation of reinforcing materials, for exampIe glass fibers (U.K. patent specification 1,111,012, U. S. Patent 3,368,955, German Auslegeschrift 2,042,447).
By virtue of its special physical properties, poly-ethylene terephthalate (PET) is particularly suitable for the production of fiber products and films, but is scarcely suitable for injection molding because high mold temperatures ~about 140C) and relatively long molding times are required for this purpose. This serious disadvantage almost completely , prevents the use of polyethyIene terephthalate for injection molding despite its high rigidity and thermal stability.
Although polypropylene terephthalate (PPT) and polybutylene terephthalate (PBT) require shorter molding times and lower mold temperatures (about 100C) by virtue of their higher crystallization rate, they show poorer physical Mo-2039-Ca PC-52~ Ca - ' .. .... _ _ _ ` ~ & 7 ~ ~
properties, in particular less thermal stability than poly~
ethylene terephthalate.
It has also besn tried to produce polycondensates which combine the favorable properties bo-th of polyethylene terephthalate and of polypropylene or polybutylene tere-phthalate. For example, it is known that the tendency towards crystallization of polyethylene terephthalate can be improved by nucleation with finely divided, solid inorganic materials (Metherlands patent specification 6,511,744).
High crystallinity guarantees hardness and dimen-sional stability, even at elevated temperatures. This high crystallinity should be reached as quickly as possible in order to ensure that optimum properties are obtained. In addition, the residence time in the mold determines the lnjection cycle, the length of which is one of the deter-mining factors of the economy of the process. Even at high mold temperatures, these cycles are too long and, for this reason, are an obstacle to the acceptance of polyethylene terephthalate for use in the production of shaped articles 2Q by injection moldlng.
SUMMARY OF_THE INVENTION
The present invention relates to a novel process for in]ection molding thermoplastic compositions which are based on polyethylene terephthalates which can be molded a-t temperatures oE less than about 120C and still produce parts of high crystallinity.
The process of the present invention broadly cowprises Mo-2039-Ca PC-52~ Ca -2-, 7 ~ 1 (a) intimately blending (i) from 70 to 98~, preferably from 85 to 95%, by weight, of a polyethylene terephthalate having an intrinsic viscosity of at least about 0.3 dl/g, preferably at least about 0.5 dl/g, measured as a 0.5%,by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25C, and . (ii) fr~om 2 to 30%, and preferably ~rom 5 to 20%, by weight~ o a multiphase composite interpolymer comprising (A) about 25 to 95 weight percent of a first elastomeric phase polymerized from a monomer system comprising : about 75 to 99.8%, by weight, Cl to C6 alkyl acrylate, 0.1 to 5%, by weight, cross-linking monomer, 0.1 ' to 5~, by weight, graftlinking ~ monomer, said cross-linking monomer being a polye*hylenlcally unsaturated monomer having a plurality of addi-tion polymerizable reactive groups, all of which polymerize at sub-stantially the same rate of reaction, and said graftlinking monomer being a polyethylenically unsaturated monomer having a plurality of addi-tion polymerizable reactive groups, . ~ at least one of which polymerizes at a substantially different rate of Mo-2039-Ca PC-52-II-Ca -3-_.. . ~ . , .
~. :
polymerization from at leas-t one other of said reactive groups; and (B) about 75 to 5 weight percent of a final, rigid thermoplastic phase which is polymerized in the presence of said elastomeric phase and which is free of epoxy groups; and (b) injection molding the resultant blend into a mold held at a temperature of no more than 120C, and no less than 80C, preferably at a temperature between 80 and 100C, said molding temperature and the amount of interpolymer being selected to yield articles with crystallinities similar to those obtainable when the same article is molded from thé
same composition without the interpolymer at mold temperatures of 140C.
DETAILED DESCRIPTION OF THE INVENTION
The invention is directed broadly to a process for injection molding an at least two-component composition, i.e., a polyalkylene terephthalate, and an in-terpolymer.
The dicarboxylic acid component of the polyethylene terephthalate (a) consists mainly o~ terephthalic acid and may contain up to l0 mol %, based on the total-mols of acid of other aromatic dlcarboxylic acids having from 6 to 14 ~ carbon atoms, of aliphatic dicarboxylic acids having from 4 to 8 carbon~atoms or of cycloaliphatic dicarboxylic acids having from 8 to 12 carbon atoms. Examples of such di-carboxylic acids which may be include~d with terephthalic Mo-2039-Ca PC-52-II-Ca -4-~,.,7 .
1 1~;6~ ~
aeid are phthalie aeid, isophthalic aeid, naphthalene-2,6-diearboxylie aeid, diphenyl-4,4'-diearboxylie aeid, adipie aeid, sebaeic acid and cyelohexanediaeetic acid.
The diol component of the polyethylene terephtha-late eonsists mainly of ethylene glyeolO It may, however, eontain Mo-2039-Ca PC-52-II-Ca -4a-~.' .
:
~ :1, 6 6 ~ 8 1 up to 10 mol ~ of aliphatic diols having froM 3 to 12 carbon atoms, cycloalipha-tic diols having from 6 to 15 carbon atoms or aromatic diols haviny from 6 to 21 carbon atoms. Examples of such additional diols ("codiols") include propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol or cyclo-hexane-1,4-dimethanol, 3-methyl-pentanediol-(2,4), 2-methyl-pentanediol-(1,4), 2,2,4-trimethylpentanediol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropanediol-~1,3), hexanediol-(1,3), 1,4-di-(~-hydroxyethoxy)-benzene, 2,2-bis (4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetra-methyl-cyclobutane, 2,2-bis~(3-~-hydroxyethoxyphenyl)-propane and 2,2~bis-(4-hydroxypropoxyphenyl)-propane.
The polyethylene terephthalates can be branched by incorporating relatively small amounts of -trihydric or tetrahydric alcohols or tribasic or tetrabasic acids, as described in German Offenlegungsschrift 1,900,270 and in U. S. Patent 3,692,744. Examples of suitablé branching agents include trimesic acid, pyromellitic acid, trimethylol-propane and ethane, and pentaerythritol. It is advisable not to use more than 1 mol % of branching agent, based on the quantity of acid component.
PoIyethylene terephthalates derived mainly from terephthalic acid and ethylene ylycol are preferred and homoethylene terephthalate, i.e. a product produced sub-stantially only from ethylene glycol and terephthalate acidor its esters, or its anhydride is most preferred.
The polyethylene kerephthalate can be prepared in known manner by (a) esterification or transesterification of Mo-2039-Ca PC-52-II-Ca -5-I lB6'781 terephthalic acid and/or of the co.rresponding I dialkyl-terephthalates, preferably the dime-thyl ester, with from 1.05 to 5.0 mol, preferably . from 1.4 to 3.6 mol of the diol, based on 1 ¦ 5 mol of the dicarboxylic acid component, and optionally the branching agent, in the presence of esterification and/or transesterifi-cation catalysts (first stage), and ¦ (b) polycondensation of the resulting reaction products in the presence of polycondensation ~ catalysts at temperatures between 200 and 320C
at reduced pressure (preferably below 1 Torr) (second stage).
Both the first step (a) and the second step (b) of condensation are usually cdrried out in the presence of catalysts, e.g. those descri.bed by R. E. Wilfong in J. Polym.
Sci. _, 385 (1961). Some of these catalys~s (A) are more powerful accelerators of the esterification reaction (a), others (B) for the polycondensation reaction (b), and still others (C) are fairly active for both (a) and (b).
The following are examples of catalysts (A) which are suitable for acceleratiny reaction (a):
1. Lithium, sodium, potassium, calclum, strontium and boron in the~ form of the metals or their oxides, hydrides, formates, acetates, alcoholates or ylycolates;
CRYSTALLIZING POLYETHYLENE TE.,REPHTHALATE
COMPOSITION AT REDUCED MOIJD TEMPERATURES
BACKGROUND OF THE INVENTION
Polyalkylene terephthalates have acquired con-siderable significance as starting materials ~or the pro duction of fibers, films and shaped articles. By virtue of their partially crystalline structure, they show outstanding properties, for example, high wear resistance, favorable creep rupture strength and high dimensional stability~ and are therefore particularly suitable for the production of shaped articles subjected to heavy mechanical and thermal stressing. An additional improvement in their mechanical properties can be obtained by the incorporation of reinforcing materials, for exampIe glass fibers (U.K. patent specification 1,111,012, U. S. Patent 3,368,955, German Auslegeschrift 2,042,447).
By virtue of its special physical properties, poly-ethylene terephthalate (PET) is particularly suitable for the production of fiber products and films, but is scarcely suitable for injection molding because high mold temperatures ~about 140C) and relatively long molding times are required for this purpose. This serious disadvantage almost completely , prevents the use of polyethyIene terephthalate for injection molding despite its high rigidity and thermal stability.
Although polypropylene terephthalate (PPT) and polybutylene terephthalate (PBT) require shorter molding times and lower mold temperatures (about 100C) by virtue of their higher crystallization rate, they show poorer physical Mo-2039-Ca PC-52~ Ca - ' .. .... _ _ _ ` ~ & 7 ~ ~
properties, in particular less thermal stability than poly~
ethylene terephthalate.
It has also besn tried to produce polycondensates which combine the favorable properties bo-th of polyethylene terephthalate and of polypropylene or polybutylene tere-phthalate. For example, it is known that the tendency towards crystallization of polyethylene terephthalate can be improved by nucleation with finely divided, solid inorganic materials (Metherlands patent specification 6,511,744).
High crystallinity guarantees hardness and dimen-sional stability, even at elevated temperatures. This high crystallinity should be reached as quickly as possible in order to ensure that optimum properties are obtained. In addition, the residence time in the mold determines the lnjection cycle, the length of which is one of the deter-mining factors of the economy of the process. Even at high mold temperatures, these cycles are too long and, for this reason, are an obstacle to the acceptance of polyethylene terephthalate for use in the production of shaped articles 2Q by injection moldlng.
SUMMARY OF_THE INVENTION
The present invention relates to a novel process for in]ection molding thermoplastic compositions which are based on polyethylene terephthalates which can be molded a-t temperatures oE less than about 120C and still produce parts of high crystallinity.
The process of the present invention broadly cowprises Mo-2039-Ca PC-52~ Ca -2-, 7 ~ 1 (a) intimately blending (i) from 70 to 98~, preferably from 85 to 95%, by weight, of a polyethylene terephthalate having an intrinsic viscosity of at least about 0.3 dl/g, preferably at least about 0.5 dl/g, measured as a 0.5%,by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25C, and . (ii) fr~om 2 to 30%, and preferably ~rom 5 to 20%, by weight~ o a multiphase composite interpolymer comprising (A) about 25 to 95 weight percent of a first elastomeric phase polymerized from a monomer system comprising : about 75 to 99.8%, by weight, Cl to C6 alkyl acrylate, 0.1 to 5%, by weight, cross-linking monomer, 0.1 ' to 5~, by weight, graftlinking ~ monomer, said cross-linking monomer being a polye*hylenlcally unsaturated monomer having a plurality of addi-tion polymerizable reactive groups, all of which polymerize at sub-stantially the same rate of reaction, and said graftlinking monomer being a polyethylenically unsaturated monomer having a plurality of addi-tion polymerizable reactive groups, . ~ at least one of which polymerizes at a substantially different rate of Mo-2039-Ca PC-52-II-Ca -3-_.. . ~ . , .
~. :
polymerization from at leas-t one other of said reactive groups; and (B) about 75 to 5 weight percent of a final, rigid thermoplastic phase which is polymerized in the presence of said elastomeric phase and which is free of epoxy groups; and (b) injection molding the resultant blend into a mold held at a temperature of no more than 120C, and no less than 80C, preferably at a temperature between 80 and 100C, said molding temperature and the amount of interpolymer being selected to yield articles with crystallinities similar to those obtainable when the same article is molded from thé
same composition without the interpolymer at mold temperatures of 140C.
DETAILED DESCRIPTION OF THE INVENTION
The invention is directed broadly to a process for injection molding an at least two-component composition, i.e., a polyalkylene terephthalate, and an in-terpolymer.
The dicarboxylic acid component of the polyethylene terephthalate (a) consists mainly o~ terephthalic acid and may contain up to l0 mol %, based on the total-mols of acid of other aromatic dlcarboxylic acids having from 6 to 14 ~ carbon atoms, of aliphatic dicarboxylic acids having from 4 to 8 carbon~atoms or of cycloaliphatic dicarboxylic acids having from 8 to 12 carbon atoms. Examples of such di-carboxylic acids which may be include~d with terephthalic Mo-2039-Ca PC-52-II-Ca -4-~,.,7 .
1 1~;6~ ~
aeid are phthalie aeid, isophthalic aeid, naphthalene-2,6-diearboxylie aeid, diphenyl-4,4'-diearboxylie aeid, adipie aeid, sebaeic acid and cyelohexanediaeetic acid.
The diol component of the polyethylene terephtha-late eonsists mainly of ethylene glyeolO It may, however, eontain Mo-2039-Ca PC-52-II-Ca -4a-~.' .
:
~ :1, 6 6 ~ 8 1 up to 10 mol ~ of aliphatic diols having froM 3 to 12 carbon atoms, cycloalipha-tic diols having from 6 to 15 carbon atoms or aromatic diols haviny from 6 to 21 carbon atoms. Examples of such additional diols ("codiols") include propane-1,3-diol, butane-1,4-diol, pentane-1,5-diol, hexane-1,6-diol or cyclo-hexane-1,4-dimethanol, 3-methyl-pentanediol-(2,4), 2-methyl-pentanediol-(1,4), 2,2,4-trimethylpentanediol-(1,3), 2-ethylhexanediol-(1,3), 2,2-diethylpropanediol-~1,3), hexanediol-(1,3), 1,4-di-(~-hydroxyethoxy)-benzene, 2,2-bis (4-hydroxycyclohexyl)-propane, 2,4-dihydroxy-1,1,3,3-tetra-methyl-cyclobutane, 2,2-bis~(3-~-hydroxyethoxyphenyl)-propane and 2,2~bis-(4-hydroxypropoxyphenyl)-propane.
The polyethylene terephthalates can be branched by incorporating relatively small amounts of -trihydric or tetrahydric alcohols or tribasic or tetrabasic acids, as described in German Offenlegungsschrift 1,900,270 and in U. S. Patent 3,692,744. Examples of suitablé branching agents include trimesic acid, pyromellitic acid, trimethylol-propane and ethane, and pentaerythritol. It is advisable not to use more than 1 mol % of branching agent, based on the quantity of acid component.
PoIyethylene terephthalates derived mainly from terephthalic acid and ethylene ylycol are preferred and homoethylene terephthalate, i.e. a product produced sub-stantially only from ethylene glycol and terephthalate acidor its esters, or its anhydride is most preferred.
The polyethylene kerephthalate can be prepared in known manner by (a) esterification or transesterification of Mo-2039-Ca PC-52-II-Ca -5-I lB6'781 terephthalic acid and/or of the co.rresponding I dialkyl-terephthalates, preferably the dime-thyl ester, with from 1.05 to 5.0 mol, preferably . from 1.4 to 3.6 mol of the diol, based on 1 ¦ 5 mol of the dicarboxylic acid component, and optionally the branching agent, in the presence of esterification and/or transesterifi-cation catalysts (first stage), and ¦ (b) polycondensation of the resulting reaction products in the presence of polycondensation ~ catalysts at temperatures between 200 and 320C
at reduced pressure (preferably below 1 Torr) (second stage).
Both the first step (a) and the second step (b) of condensation are usually cdrried out in the presence of catalysts, e.g. those descri.bed by R. E. Wilfong in J. Polym.
Sci. _, 385 (1961). Some of these catalys~s (A) are more powerful accelerators of the esterification reaction (a), others (B) for the polycondensation reaction (b), and still others (C) are fairly active for both (a) and (b).
The following are examples of catalysts (A) which are suitable for acceleratiny reaction (a):
1. Lithium, sodium, potassium, calclum, strontium and boron in the~ form of the metals or their oxides, hydrides, formates, acetates, alcoholates or ylycolates;
2. Calcium and strontium chlorides and bromides;
3.~ Tertiary amines;
4. Calcium and strontium malonates, adipates, benzoates, etc.;
Mo-2039-Ca PC-52~ Ca -6-7 ~ ~
Mo-2039-Ca PC-52~ Ca -6-7 ~ ~
5. Lithium salts of dithiocarbamic acids.
The following are examples of catalysts ~B) sui~able for the polycondensation reaction (b):
1. Molybdenum, germanium, lead, tin and antimony in the form of the metals or their oxides, hydrides, formates, alcoholates or glycolates;
2. Zinc and lead perborates and borates;
3. Zinc, manganese(II), cobalt, magnesium, chromium, iron and cadmium succinates, butyrates, adipates or enolates of a diketone;
4. zinc chloride and bromide;
5. Lanthanum dioxide and titanate;
The following are examples of catalysts ~B) sui~able for the polycondensation reaction (b):
1. Molybdenum, germanium, lead, tin and antimony in the form of the metals or their oxides, hydrides, formates, alcoholates or glycolates;
2. Zinc and lead perborates and borates;
3. Zinc, manganese(II), cobalt, magnesium, chromium, iron and cadmium succinates, butyrates, adipates or enolates of a diketone;
4. zinc chloride and bromide;
5. Lanthanum dioxide and titanate;
6. Neodymium chloride;
7. Mixed salts of antimony, e.y. potassium antimony lS tartrate, and salts of antimonic acids, such as potassium pyroantimonate;
8. Zinc or manganese salts of dithiocarbamic acids;
9. Cobalt naphthenate;
10~ Titanium tetrafluoride or tetrachloride;
11. Alkyl ortho-titanates;
12. Titanium tetrachloride ether complexes;
13. Quaternary ammonium salts carrying a titanium hexaalkoxy group: titanium tetraalkoxides, alkali metal or alkallne earth metal compounds of aluminum, zirconium or titanium alkoxides;
~ 14. Organic quaternary ammonium, sulphonium, phosphonium and oxonium hydroxides and salts;
15. Barium malonate, adipate, benzoate, etc.;
16. Lead, zinc, cadmium or manganese salts o~ the monoalkyl ester o~ a phenylene dicarboxylic acid;
Mo-2039-Ca PC-52-II-Ca -7--~ J ~66'~ ~
17. Antimony catechuic complexes with an amino alcohol or with an amine and an alcohol;
18. Uranium trioxide, tetrahalide, nitrate, sulphate or acetate.
The following are examples of catalysts tC) which are suitable ~or accelerating both steps (a) and (b~ of the reaction:
1. Barium, magnesium, zinc, cadmium, aluminurn, manganese and cobalt as the metals or ~heir oxides, hydrides, formates, alcoholates, glycolates or preferably, as acetates;
2. Aluminum chloride and bromide;
3. Zinc, manganese(II), cobalt, magnesium, chromium, iron and cadmium succinates, butyrates, adipa~es F enolates of a diketone.
The most suitable compounds for use as catalysts (A) are calcium, zinc and manganese salts, particularly the acetates.
The most suitable catalysts (B) are the compounds of zinc, manganese, cobalt, antimony, germanium, titanium and tin, e.g. zinc and manganese acetate, antimony trioxide, trichlorlde and triacetate, and germanium dioxide and tetrachloride.
The most suitable catalysts (C) are particularly the titanium compounds, e.g~ tetraalkyltitanium acid esters having alkyl groups Wit}l from 1 to 10 carbon atoms, such as tetraisopropyltitanate and tetrabutyltitanatet The catalysts are used in quantities o~ ~rom 0.001 to 0.~2~ by weight, based on the dicarboxylic acid components.
Mo-2039-Ca PC-52-II-Ca -8-, 6 ~
Inhibitors may be added ln the process -to inhibit the catalysts (A) after completion of the irst reaction step (a) and to increase the stability of the end product (cf. "Polyesterfasern" by H. Ludewig, 2nd Edition, publishers ¦ 5 Akademie-Verlag, Berlin 1974). The following are examples of such inhibitors: phosphoric acid, phosphorous acid and I aliphatic, aromatic and araliphatic esters thereof, e.g.
the alkyl esters having from 6 to 18 carbon atoms in the alcohol component, phenyl esters in which the phenyl groups can carry 1 to 3 substituents having 6 to 18 carbon a-toms, ~-such as trinonylphenyl phosphate, dodecyl phenyl phosphate or triphenyl phosphate. These inhibitors are usually added in quantities of from 0.01 to 0.6%, by weight, based on the dicarboxylic acid component.
In order to obtain an even higher molecular weight, the polyethylene terephthalates may be subjected to a solid phase polycondensation. This is generally carried out by subjecting the granulated product to a temperature which is from 60 to 6C below the melting point of the polymer, ei-ther in a stream of nitrogen ox under a vacuum of less than 1 Torr.
The second component of the instant invention is a multiphase composite interpolymer comprising about 25 to 95 weight percent of a first elastomeric phase and about 75 to 5 weight percent of a final rigid thermoplastic phase. One or more intermediate phases are optional, for example a middle stage polymerized from about 75 to 100 percen-t,b~ weight, styrene. The first stage is polymerized from about 75 to 98.8 weight percent Cl to C6 acrylate resulting in an acrylic rubber core having a Tg below about 10C and cross-Mo-2039-Ca PC-52-II-Ca -9-linked with 0.1 to 5 wei~ht percent cxoss-linking monomer and further containing 0.1 to 5 percent,by weight,graft-linking monomer. The preferred alkyl acrylate is butyl acrylate. The cross-linking monomer is a polyethylenically unsaturated mcnomer having a plurality of addition poly-merizable reactive groups, all of which polymerize at sub-stantially the same rate of reaction. Suitable cross-linking monomers include polyacrylic and polymethacrylic esters of polyols such as butylene diacrylate and dimeth-acrylate, trimethylol propane trimethacrylate, and the like;di- and trivinyl benzene, vinyl acrylate and methacrylate, and the like. The preferred cross-linking monomer is butylene diacrylate. The graftlinking monomer is a poly-ethylenically unsaturated monomer having a plurality of addition polymerizable reactive groups, at least one of which polymerizing atasubstantially different rate of polymerization from at least one other of said reactive groups. The function of the graftlinking monomer is to provide a residual level of unsaturation in the elastomeric phase, particularly in the latter stages of polymerization and, consequently, at or near the surface of the elastomer particles. When the rigid thermoplastic phase is sub~
sequently polyn~erized at the surface of the elastomer, the residual unsaturated addition polymerizable reactive group contributed by the graftlinking monomer participates in the subsequent reaction so that at least a portion of the rigid phase is chemically attached to the ~surface of the elastomer. Among the effective graftlinking monomers are allyl group-containing monomers of allyl esters of ethylenically unsaturated acids such as allyl acrylate, Mo-2039-Ca PC-52-I-I-Ca -10-.
l 1~6~7~
~llyl methacrylate, diallyl maleate, diallyl fumara-te, diallyl itaconate, allyl acid maleake, allyl acid fumarate and allyl acid itaconate. Somewhat less preferred are the diallyl esters of polycarboxylic acids which do not contain polymerizable unsaturation. The preferred graftlinking monomers are allyl methacrylate and diallyl maleate. A
most preferred interpolymer has only two stages, the first stage comprising about 60 to 95 percent,by weight,of the interpolymer and being polymerized from a monomer system comprising 95 to 99.8%,by weight,butyl acrylate, 0.1 to 2.5~, by weight, butylene diacrylate as cross-linking agent, 0.1 to 2.5%, by weight, allyl methacrylate or diallyl maleate as a graftlinking agent, with a final stage polymerized from about 60 to 100%, by weight, methyl methacrylate.
The final stage monomer system can be comprised of Cl to C16 methacrylate, styrene, acrylonitrile, alkyl acrylates, allyl methacrylate, diallyl methacrylate, and the like, as long as the over Tg is at least 20C.
Preerably, the final stage monomer system is at least 50 weight percent Cl to C4 alkyl methacrylate. It is further preferred that the final stage polymer be free of units which tend to degrade poly(alkylene terephthalates), for example acid, hydroxyl amino and amide groups.
The presently preferred interpolymer is one produced using conventional emulsion polymerization from 79.2 parts of N-butyl acrylate, 0.4 parts of 1,3-butylene diacrylate, and 0.4 parts of diallyl maleate in a fir~t stage, and 20 parts of methylmethacrylate in a second stage.
The interpolymers useful in the instant inventioll are known Mo-2039-Ca PC-52-II-Ca -11-67~ 3 and have been described in U. S. Patents 3,808,180 and ¦4,096,202. In fact, according to U. S~ Patent 4,09&,202, the interpolymers are useful as impact modifiers for poly-ethylene terephthalate. What is not recognized is that ¦5 these interpolymers can be used to increase the crystalliza-tion rate of PET resins and can allow for the molding of products at relatively low temperatures while obtaining high degrees of crystallinity.
A composition which i9 particularly suitable for molding into molds held at such reduced temperatures is one which,in addition to the above-specified composite inter-polymer, also contains between 20 and 45 weight percent, based on the composition, of glass fibers.
The amounts of components present may vary over a wlde ranger Generally, the compositions should containfrom 70 to 98~ and preferably 85 to 95%, by weight, of polyethylene terephthalate and from 2 to 30% and preferably 5 to 20~, by weiyht, o~ the interpolymer.
Injection molding conditions for polyethylene terephthalates are well known to those skilled in the art and are taught in U. S. Patent 3,516,957, and Injection Moldin~ _heory and Practice, by Ervin I. Rubin, published by Wiley Interscience, 1972. Generally, these conditions involve temperatures of between about 250 and 310C, residence times at elevated temperatures of between about 1 and 15 minutes, pressures of up -to about 20,000 psi and shear rates of between about 100 and 10,000 reciprocal seconds. These conditions may also include vacuum.s of down to 20 inches of ~Ig. OE course, these conditions Mo-2039-Ca PC-52-II-Ca -12-_,_ . ., . . ..... ,. .. _ . ~_ . . . -- .. .. __ = ...... u .. . . . --also include molcl temperatures oE between about 100 and200C but,as will become apparent, the composition of the present invention may be molded at lower ~emperatures and shorter mold times.
The mixtures of polyethylene terephthalate and interpolymer can be obtained in usual commercial mixing apparatus such as kneaders and one-shaft or two-shaft screw extruders. The solidified melt of the mix-tures can be granulated for further processingj and this can be followed by a postcondensation in the solid phase.
The compositions of the present invention may be molded at temperatures of between 70C and about 120C and still yield relatively high crystallinity. When used in compositions of the present invention, these polymers may be molded under much less favora~le conditions (colder molds, e.g. below about 120C, and shorter residence time in the mold, e.g. less than about 60 seconds) and still display crystallinities similar to those obtainable under optimum conditions (i.e. high mold temperature and long residence time). Thus, the present invention includes a process for molding resins based primarily, and pxeferably solely, upon terephthalic acid and ethylene glycol at mold temperatures of less than about 120C while attaining degrees oE
crystallinity similar to those obtainable under optimum injection molding conditions with the polyester alone or the polyester and glass fiber alone.
The process comprises intimately blending the terephthalic acid/ethylene glycol based resin and inter-polymer and injection molding the composition so prepared Mo-2039-Ca PC-52-II-Ca -13-' 3~
into molds held at temperatures less than about 120C, preferably less than about 110C and greater than 80C.
The polyester consists of acid residues of which at least 90 mol % are derived from terephthalic acid and,of alcohol residues of which at least 90 mol ~ are derived from ethylene glycol and most preferably is a homopolyethylene terephthalate. The other components of the polyester may be any of those discussed hereinabove as being suitable.
The polyester should have a minimum intrinsic viscosity of about 0.3 dl/g, preferably 0.5 dl/g (measured as a 0.5~
-strength by weight solution in a phenol/tetrachloroethane mixture in a weight ratio of 1:1 at 25C).
In a preferred embodiment of -this process aspect of the present invention, the reside~ce time in the mold is significantly less than that required for the unmodified polyester (e.g. pure resin) in making the same part. For small, fairly simple parts this may be less than about 30 seconds, more preferably less than about 20 se'conds and most preferably less than 10 seconds as compared to 40 seconds or more for unmodified resin. Of course, significant reductions in the mold residence time of resins modified with conventional additives such as micro talc nucleating agent are also obtained by further modifying these resins with appropriate amounts of the imide group containing compound of the present invention.
The usua'l quantities of stabilizers, preferably from 0.01 to 0.5%, by weight, based on the weight of -the polyethylene terephthalates can be added to protect against thermooxidative degradation. Suitable stabilizers include Mo-2039-Ca PC-52~ Ca -14-8~78 1 phenols and phenol derivatives, particularly sterically hindered phenols which have alkyl substituents with 1 to 6 carbon atoms in both ortho-positions to the phenolic hydroxyl group, amines, preferably secondary arylamines and their derivatives, phosphates and phosphites, pre~erably their aryl derivatives, quinones, copper salts of organic acids, addition compounds of copper(I) halides with phosphites, e.g. ~,4'-bis-(2,6-di-tert.-butylphenol);
1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxy-benzyl)-benzene; ~,4'-bukylidene-bis-(6-tert.-butyl-m-cresol); 3,5-di-tert.-butyl-4-hydroxybenzyl-phosphonic acid diethyl ester; N,N'-bis-(~-naphthyl)-p-phenylenediamine;
N,N'-bis-(l-methylheptyl)-p-phenylenediamine; phenyl-~-naphthylamine; 4,4'-bis-(~,~-dimethylbenzyl)-diphenylamine;
1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxy-hydrocinnamoyl)-hexahydro-s-kriazine; hydroquinone; p-benzoquinone, tolu-hydroquinone; p-tert.-butyl pyrocatechol; chloranil;
naphthoquinone; copper naphthenate; copper octoate; CU(I)Cl/
triphenyl phosphate; CU(I)Cl/trimethylphosphite; CU(I)Cl/
tris-chloroethylphosphite; CU(I)Cl/tripropylphosphite; and p-nitrosodimethylaniline. Also suitable as stabilizing agents against molecular weight degradation from hydrolysis are carbodiimides.
Inorganic or organic pigments, dyes, lubricants, fillers such as glass fibers, and mold release agents such as zinc stearate, montan wax, UV absorbers and the like can also be added in the usual quantities.
Flame-retardant materials can be added in amounts of from 2 to 20~, by weight, based on the composition. Such Mo-2039-Ca PC-52-II-Ca -15-3 6 ~
known flame-retarding agen-ts include halogen-con-taininy compounds, elementary phosphorus or phosphorus compounds, phosphorus-nitrogen compounds, antimony trioxide or mixtures thereof. Speclfic materials include antimony, S trioxide, decabromobiphenyl ether and tetrabromobisphenol-A
polycarbonate.
~ he crystallization velocity of the thermoplastic polyester molding composi-tions can be even further increased by adding nucleating agents in quantities of from 0.01 to 1%, by weight, based on the quantity of polyester. Compounds of this kind are known in the art (cf. Kunststoff-Handbuch, Volume VIII, "Polyester", Carl Hanser Verlag, Munich 1973, page 701).
The thermoplastic compositions of this invention are suitable for the manufacture of all kinds of molded articles by injection molding and also for the production of films and fibers.
In all of the Examples which follow, the composi-tions were prepared for extrusion by tumbling polyethylene terephthalate pellets with all the indicated additives, all of which were in powder form, for two and one-half minutes and then, when indicated, the composition was tumbled an additional twenty seconds with the chopped strand glass fibers.
These tumble blended compositions were extruded to pellets in a Waldron-Hartig 1-1/2i' single screw extruder with a 24:1 I./D ~arrel, nonvented and fitted with a 2.75:1 CR screw (feed, 6 flights; meter, 12 flights at 0.115 inches) Mo-2039-Ca PC-52 II-Ca -16~
-~ 8 ~ 7 33 1 containing four rows of mixing pins 5.25 inche~ apart and ! each pin 0.25 inches apart. A 40,60,20 mesh screen assembly was used except when fiberglass or Sb2O3 were part of the I composition. The temperature profile was 250C at the rear, ¦ 5 middle, front and die. The melt temperature was 255-260C, the die pressure was 0 psi and the screw was operated at 50 rpm.
¦ Test specimens were molded from the extruded pellets ¦ using a Newbury Industries 4 oz. capacity reciprocal screw injection machine. The thermal profile was 250C at the ! rear and front and 240C at the nozzle. No primary injection was used; the secondary injection time was 10 seconds and the cure time was 10 seconds for a cycle time of 20 seconds.
The primary pressure was 300 psi; the secondary pressure was 0 psi and the back pressure was 50 psi. The ram speed was 70% of maximum.
The mold was held at a temperature of 100C and consisted of a family of cavities providing:
4" diameter x 1/4" disc 4" diameter x 1/8" disc 4" diameter x 1/10" disc 4" diameter x 1/16" disc.
All cavities were chrome plated DME No. 3 steel and were equipped with runner shu-t-offs.
Mo-2039-Ca PC-52-II-Ca 17 EXAMPLES
- EXAMPLES 1-4 AND COMPARISON EXAMPLES l-4 The materials and amounts of materials (in parts by weight) were as indicated in Table I. The parts noted were tested for warpage. In testing for warpage, discs are molded at 250C melt temperature in a mold kept at 100C
with a cycle time of 20 seconds. Upon annealing at 150C
for 24 hours, shrinkage (if any) will cause the disc to curl. The measurement (in mm) reported is the depth of the `concave curvature formed. The lower the number, the higher the degree of crystallinity. The discs are tested in sizes of 1/8" x~4" (diameter) and 1/16" x 4".
TABLE I
Unreinforced _ Glass Fïber Reinforced Comp. Comp. Comp. Comp Example Example Example Example Example Example Example Exampie Example 1 1 2 2 3 3 4 4 VFR 5041 9 10 - - 6.3 7.0 - ~ -TENITE 7741 - - 9 10 - - 6.3 7.0 KM 330 1 - 1 - 0.7 - 0.7 K419AA - - - 3.0 3 0 3 0 3 0 1/8" x 4"
Before Ann. 1. 40 4.38 1.25 3.52 1.52 3.35 0.70 2.85 25 After Ann. 1.40 4.83 1.25 3.58 1.22 3.22 0.80 1.92 1/16" x 4"
Before Ann. 2.20 - 2.05 - 2.17 4.62 1.95 3.95 After Ann. 2.52 - 1.30 - 2.92 4.85 2.75 4.44 v ~ . ~ .. . . _ . _ . . . _ . .. .. _ _ VFR 5041: A polyethylene terephthalate available from Goodyear, having an intrinsic viscosity of 1.04 dl/g measured as a 0.5~, by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25C.
Mo-2039-Ca PC-52~ Ca -18-; r7 ~3 ~
TENITE 7741: A polyethylene terephthalate available from Eastman Kodak, havlng an intrinsic viscosity of 0.54 dl/g measured as a 0.5%, by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25C.
K419AA: Chopped strand glass fiber available from Owens Corning Fiberglas.
KM 330: A multiphase composite interpolymer available from Rohm and Haas based on n-butyl acrylate, 1,3-butylene diacrylate, diallyl maleate and methyl-m~thacrylate produced according to Example 26 of U.S.
Patent 4,096,202.
All evaluated compositions contained a nucleating amount of micro talc and a low level (less than 0.3 wt. %) of a stabilizing system not believed to affect the crystal-lization behavior of the compositions.
The lower degree of warpage observed for thecompositions containing the composite i~terpolymer is evidence that these compositions have improved or accelerated crystallization velocities. Thus, with appropriate tailoring of the part geometry and molding conditions, it is possible to obtain fully crystallized and therefore warpage-free parts at lower temperatures and with faster mold cycles than would be possible with compositions not containing this additive. The prior art has generally not recognized the possibility of molding into molds at temperatures significant-ly below 140C, particularly below 120C, and still obtaining highly crystalline parts not requiring further heat treatment.
Mo-2039-Ca -19-1 Trademark of Eastman Chemical Company Although the invention has been described in detail 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 spirit and scope of the invention except as it may be limited by the claims.
Mo-2039~Ca PC-52-II-Ca -20-., ... , ., __ ~, ~_-- - .
~ 14. Organic quaternary ammonium, sulphonium, phosphonium and oxonium hydroxides and salts;
15. Barium malonate, adipate, benzoate, etc.;
16. Lead, zinc, cadmium or manganese salts o~ the monoalkyl ester o~ a phenylene dicarboxylic acid;
Mo-2039-Ca PC-52-II-Ca -7--~ J ~66'~ ~
17. Antimony catechuic complexes with an amino alcohol or with an amine and an alcohol;
18. Uranium trioxide, tetrahalide, nitrate, sulphate or acetate.
The following are examples of catalysts tC) which are suitable ~or accelerating both steps (a) and (b~ of the reaction:
1. Barium, magnesium, zinc, cadmium, aluminurn, manganese and cobalt as the metals or ~heir oxides, hydrides, formates, alcoholates, glycolates or preferably, as acetates;
2. Aluminum chloride and bromide;
3. Zinc, manganese(II), cobalt, magnesium, chromium, iron and cadmium succinates, butyrates, adipa~es F enolates of a diketone.
The most suitable compounds for use as catalysts (A) are calcium, zinc and manganese salts, particularly the acetates.
The most suitable catalysts (B) are the compounds of zinc, manganese, cobalt, antimony, germanium, titanium and tin, e.g. zinc and manganese acetate, antimony trioxide, trichlorlde and triacetate, and germanium dioxide and tetrachloride.
The most suitable catalysts (C) are particularly the titanium compounds, e.g~ tetraalkyltitanium acid esters having alkyl groups Wit}l from 1 to 10 carbon atoms, such as tetraisopropyltitanate and tetrabutyltitanatet The catalysts are used in quantities o~ ~rom 0.001 to 0.~2~ by weight, based on the dicarboxylic acid components.
Mo-2039-Ca PC-52-II-Ca -8-, 6 ~
Inhibitors may be added ln the process -to inhibit the catalysts (A) after completion of the irst reaction step (a) and to increase the stability of the end product (cf. "Polyesterfasern" by H. Ludewig, 2nd Edition, publishers ¦ 5 Akademie-Verlag, Berlin 1974). The following are examples of such inhibitors: phosphoric acid, phosphorous acid and I aliphatic, aromatic and araliphatic esters thereof, e.g.
the alkyl esters having from 6 to 18 carbon atoms in the alcohol component, phenyl esters in which the phenyl groups can carry 1 to 3 substituents having 6 to 18 carbon a-toms, ~-such as trinonylphenyl phosphate, dodecyl phenyl phosphate or triphenyl phosphate. These inhibitors are usually added in quantities of from 0.01 to 0.6%, by weight, based on the dicarboxylic acid component.
In order to obtain an even higher molecular weight, the polyethylene terephthalates may be subjected to a solid phase polycondensation. This is generally carried out by subjecting the granulated product to a temperature which is from 60 to 6C below the melting point of the polymer, ei-ther in a stream of nitrogen ox under a vacuum of less than 1 Torr.
The second component of the instant invention is a multiphase composite interpolymer comprising about 25 to 95 weight percent of a first elastomeric phase and about 75 to 5 weight percent of a final rigid thermoplastic phase. One or more intermediate phases are optional, for example a middle stage polymerized from about 75 to 100 percen-t,b~ weight, styrene. The first stage is polymerized from about 75 to 98.8 weight percent Cl to C6 acrylate resulting in an acrylic rubber core having a Tg below about 10C and cross-Mo-2039-Ca PC-52-II-Ca -9-linked with 0.1 to 5 wei~ht percent cxoss-linking monomer and further containing 0.1 to 5 percent,by weight,graft-linking monomer. The preferred alkyl acrylate is butyl acrylate. The cross-linking monomer is a polyethylenically unsaturated mcnomer having a plurality of addition poly-merizable reactive groups, all of which polymerize at sub-stantially the same rate of reaction. Suitable cross-linking monomers include polyacrylic and polymethacrylic esters of polyols such as butylene diacrylate and dimeth-acrylate, trimethylol propane trimethacrylate, and the like;di- and trivinyl benzene, vinyl acrylate and methacrylate, and the like. The preferred cross-linking monomer is butylene diacrylate. The graftlinking monomer is a poly-ethylenically unsaturated monomer having a plurality of addition polymerizable reactive groups, at least one of which polymerizing atasubstantially different rate of polymerization from at least one other of said reactive groups. The function of the graftlinking monomer is to provide a residual level of unsaturation in the elastomeric phase, particularly in the latter stages of polymerization and, consequently, at or near the surface of the elastomer particles. When the rigid thermoplastic phase is sub~
sequently polyn~erized at the surface of the elastomer, the residual unsaturated addition polymerizable reactive group contributed by the graftlinking monomer participates in the subsequent reaction so that at least a portion of the rigid phase is chemically attached to the ~surface of the elastomer. Among the effective graftlinking monomers are allyl group-containing monomers of allyl esters of ethylenically unsaturated acids such as allyl acrylate, Mo-2039-Ca PC-52-I-I-Ca -10-.
l 1~6~7~
~llyl methacrylate, diallyl maleate, diallyl fumara-te, diallyl itaconate, allyl acid maleake, allyl acid fumarate and allyl acid itaconate. Somewhat less preferred are the diallyl esters of polycarboxylic acids which do not contain polymerizable unsaturation. The preferred graftlinking monomers are allyl methacrylate and diallyl maleate. A
most preferred interpolymer has only two stages, the first stage comprising about 60 to 95 percent,by weight,of the interpolymer and being polymerized from a monomer system comprising 95 to 99.8%,by weight,butyl acrylate, 0.1 to 2.5~, by weight, butylene diacrylate as cross-linking agent, 0.1 to 2.5%, by weight, allyl methacrylate or diallyl maleate as a graftlinking agent, with a final stage polymerized from about 60 to 100%, by weight, methyl methacrylate.
The final stage monomer system can be comprised of Cl to C16 methacrylate, styrene, acrylonitrile, alkyl acrylates, allyl methacrylate, diallyl methacrylate, and the like, as long as the over Tg is at least 20C.
Preerably, the final stage monomer system is at least 50 weight percent Cl to C4 alkyl methacrylate. It is further preferred that the final stage polymer be free of units which tend to degrade poly(alkylene terephthalates), for example acid, hydroxyl amino and amide groups.
The presently preferred interpolymer is one produced using conventional emulsion polymerization from 79.2 parts of N-butyl acrylate, 0.4 parts of 1,3-butylene diacrylate, and 0.4 parts of diallyl maleate in a fir~t stage, and 20 parts of methylmethacrylate in a second stage.
The interpolymers useful in the instant inventioll are known Mo-2039-Ca PC-52-II-Ca -11-67~ 3 and have been described in U. S. Patents 3,808,180 and ¦4,096,202. In fact, according to U. S~ Patent 4,09&,202, the interpolymers are useful as impact modifiers for poly-ethylene terephthalate. What is not recognized is that ¦5 these interpolymers can be used to increase the crystalliza-tion rate of PET resins and can allow for the molding of products at relatively low temperatures while obtaining high degrees of crystallinity.
A composition which i9 particularly suitable for molding into molds held at such reduced temperatures is one which,in addition to the above-specified composite inter-polymer, also contains between 20 and 45 weight percent, based on the composition, of glass fibers.
The amounts of components present may vary over a wlde ranger Generally, the compositions should containfrom 70 to 98~ and preferably 85 to 95%, by weight, of polyethylene terephthalate and from 2 to 30% and preferably 5 to 20~, by weiyht, o~ the interpolymer.
Injection molding conditions for polyethylene terephthalates are well known to those skilled in the art and are taught in U. S. Patent 3,516,957, and Injection Moldin~ _heory and Practice, by Ervin I. Rubin, published by Wiley Interscience, 1972. Generally, these conditions involve temperatures of between about 250 and 310C, residence times at elevated temperatures of between about 1 and 15 minutes, pressures of up -to about 20,000 psi and shear rates of between about 100 and 10,000 reciprocal seconds. These conditions may also include vacuum.s of down to 20 inches of ~Ig. OE course, these conditions Mo-2039-Ca PC-52-II-Ca -12-_,_ . ., . . ..... ,. .. _ . ~_ . . . -- .. .. __ = ...... u .. . . . --also include molcl temperatures oE between about 100 and200C but,as will become apparent, the composition of the present invention may be molded at lower ~emperatures and shorter mold times.
The mixtures of polyethylene terephthalate and interpolymer can be obtained in usual commercial mixing apparatus such as kneaders and one-shaft or two-shaft screw extruders. The solidified melt of the mix-tures can be granulated for further processingj and this can be followed by a postcondensation in the solid phase.
The compositions of the present invention may be molded at temperatures of between 70C and about 120C and still yield relatively high crystallinity. When used in compositions of the present invention, these polymers may be molded under much less favora~le conditions (colder molds, e.g. below about 120C, and shorter residence time in the mold, e.g. less than about 60 seconds) and still display crystallinities similar to those obtainable under optimum conditions (i.e. high mold temperature and long residence time). Thus, the present invention includes a process for molding resins based primarily, and pxeferably solely, upon terephthalic acid and ethylene glycol at mold temperatures of less than about 120C while attaining degrees oE
crystallinity similar to those obtainable under optimum injection molding conditions with the polyester alone or the polyester and glass fiber alone.
The process comprises intimately blending the terephthalic acid/ethylene glycol based resin and inter-polymer and injection molding the composition so prepared Mo-2039-Ca PC-52-II-Ca -13-' 3~
into molds held at temperatures less than about 120C, preferably less than about 110C and greater than 80C.
The polyester consists of acid residues of which at least 90 mol % are derived from terephthalic acid and,of alcohol residues of which at least 90 mol ~ are derived from ethylene glycol and most preferably is a homopolyethylene terephthalate. The other components of the polyester may be any of those discussed hereinabove as being suitable.
The polyester should have a minimum intrinsic viscosity of about 0.3 dl/g, preferably 0.5 dl/g (measured as a 0.5~
-strength by weight solution in a phenol/tetrachloroethane mixture in a weight ratio of 1:1 at 25C).
In a preferred embodiment of -this process aspect of the present invention, the reside~ce time in the mold is significantly less than that required for the unmodified polyester (e.g. pure resin) in making the same part. For small, fairly simple parts this may be less than about 30 seconds, more preferably less than about 20 se'conds and most preferably less than 10 seconds as compared to 40 seconds or more for unmodified resin. Of course, significant reductions in the mold residence time of resins modified with conventional additives such as micro talc nucleating agent are also obtained by further modifying these resins with appropriate amounts of the imide group containing compound of the present invention.
The usua'l quantities of stabilizers, preferably from 0.01 to 0.5%, by weight, based on the weight of -the polyethylene terephthalates can be added to protect against thermooxidative degradation. Suitable stabilizers include Mo-2039-Ca PC-52~ Ca -14-8~78 1 phenols and phenol derivatives, particularly sterically hindered phenols which have alkyl substituents with 1 to 6 carbon atoms in both ortho-positions to the phenolic hydroxyl group, amines, preferably secondary arylamines and their derivatives, phosphates and phosphites, pre~erably their aryl derivatives, quinones, copper salts of organic acids, addition compounds of copper(I) halides with phosphites, e.g. ~,4'-bis-(2,6-di-tert.-butylphenol);
1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert.-butyl-4-hydroxy-benzyl)-benzene; ~,4'-bukylidene-bis-(6-tert.-butyl-m-cresol); 3,5-di-tert.-butyl-4-hydroxybenzyl-phosphonic acid diethyl ester; N,N'-bis-(~-naphthyl)-p-phenylenediamine;
N,N'-bis-(l-methylheptyl)-p-phenylenediamine; phenyl-~-naphthylamine; 4,4'-bis-(~,~-dimethylbenzyl)-diphenylamine;
1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxy-hydrocinnamoyl)-hexahydro-s-kriazine; hydroquinone; p-benzoquinone, tolu-hydroquinone; p-tert.-butyl pyrocatechol; chloranil;
naphthoquinone; copper naphthenate; copper octoate; CU(I)Cl/
triphenyl phosphate; CU(I)Cl/trimethylphosphite; CU(I)Cl/
tris-chloroethylphosphite; CU(I)Cl/tripropylphosphite; and p-nitrosodimethylaniline. Also suitable as stabilizing agents against molecular weight degradation from hydrolysis are carbodiimides.
Inorganic or organic pigments, dyes, lubricants, fillers such as glass fibers, and mold release agents such as zinc stearate, montan wax, UV absorbers and the like can also be added in the usual quantities.
Flame-retardant materials can be added in amounts of from 2 to 20~, by weight, based on the composition. Such Mo-2039-Ca PC-52-II-Ca -15-3 6 ~
known flame-retarding agen-ts include halogen-con-taininy compounds, elementary phosphorus or phosphorus compounds, phosphorus-nitrogen compounds, antimony trioxide or mixtures thereof. Speclfic materials include antimony, S trioxide, decabromobiphenyl ether and tetrabromobisphenol-A
polycarbonate.
~ he crystallization velocity of the thermoplastic polyester molding composi-tions can be even further increased by adding nucleating agents in quantities of from 0.01 to 1%, by weight, based on the quantity of polyester. Compounds of this kind are known in the art (cf. Kunststoff-Handbuch, Volume VIII, "Polyester", Carl Hanser Verlag, Munich 1973, page 701).
The thermoplastic compositions of this invention are suitable for the manufacture of all kinds of molded articles by injection molding and also for the production of films and fibers.
In all of the Examples which follow, the composi-tions were prepared for extrusion by tumbling polyethylene terephthalate pellets with all the indicated additives, all of which were in powder form, for two and one-half minutes and then, when indicated, the composition was tumbled an additional twenty seconds with the chopped strand glass fibers.
These tumble blended compositions were extruded to pellets in a Waldron-Hartig 1-1/2i' single screw extruder with a 24:1 I./D ~arrel, nonvented and fitted with a 2.75:1 CR screw (feed, 6 flights; meter, 12 flights at 0.115 inches) Mo-2039-Ca PC-52 II-Ca -16~
-~ 8 ~ 7 33 1 containing four rows of mixing pins 5.25 inche~ apart and ! each pin 0.25 inches apart. A 40,60,20 mesh screen assembly was used except when fiberglass or Sb2O3 were part of the I composition. The temperature profile was 250C at the rear, ¦ 5 middle, front and die. The melt temperature was 255-260C, the die pressure was 0 psi and the screw was operated at 50 rpm.
¦ Test specimens were molded from the extruded pellets ¦ using a Newbury Industries 4 oz. capacity reciprocal screw injection machine. The thermal profile was 250C at the ! rear and front and 240C at the nozzle. No primary injection was used; the secondary injection time was 10 seconds and the cure time was 10 seconds for a cycle time of 20 seconds.
The primary pressure was 300 psi; the secondary pressure was 0 psi and the back pressure was 50 psi. The ram speed was 70% of maximum.
The mold was held at a temperature of 100C and consisted of a family of cavities providing:
4" diameter x 1/4" disc 4" diameter x 1/8" disc 4" diameter x 1/10" disc 4" diameter x 1/16" disc.
All cavities were chrome plated DME No. 3 steel and were equipped with runner shu-t-offs.
Mo-2039-Ca PC-52-II-Ca 17 EXAMPLES
- EXAMPLES 1-4 AND COMPARISON EXAMPLES l-4 The materials and amounts of materials (in parts by weight) were as indicated in Table I. The parts noted were tested for warpage. In testing for warpage, discs are molded at 250C melt temperature in a mold kept at 100C
with a cycle time of 20 seconds. Upon annealing at 150C
for 24 hours, shrinkage (if any) will cause the disc to curl. The measurement (in mm) reported is the depth of the `concave curvature formed. The lower the number, the higher the degree of crystallinity. The discs are tested in sizes of 1/8" x~4" (diameter) and 1/16" x 4".
TABLE I
Unreinforced _ Glass Fïber Reinforced Comp. Comp. Comp. Comp Example Example Example Example Example Example Example Exampie Example 1 1 2 2 3 3 4 4 VFR 5041 9 10 - - 6.3 7.0 - ~ -TENITE 7741 - - 9 10 - - 6.3 7.0 KM 330 1 - 1 - 0.7 - 0.7 K419AA - - - 3.0 3 0 3 0 3 0 1/8" x 4"
Before Ann. 1. 40 4.38 1.25 3.52 1.52 3.35 0.70 2.85 25 After Ann. 1.40 4.83 1.25 3.58 1.22 3.22 0.80 1.92 1/16" x 4"
Before Ann. 2.20 - 2.05 - 2.17 4.62 1.95 3.95 After Ann. 2.52 - 1.30 - 2.92 4.85 2.75 4.44 v ~ . ~ .. . . _ . _ . . . _ . .. .. _ _ VFR 5041: A polyethylene terephthalate available from Goodyear, having an intrinsic viscosity of 1.04 dl/g measured as a 0.5~, by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25C.
Mo-2039-Ca PC-52~ Ca -18-; r7 ~3 ~
TENITE 7741: A polyethylene terephthalate available from Eastman Kodak, havlng an intrinsic viscosity of 0.54 dl/g measured as a 0.5%, by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25C.
K419AA: Chopped strand glass fiber available from Owens Corning Fiberglas.
KM 330: A multiphase composite interpolymer available from Rohm and Haas based on n-butyl acrylate, 1,3-butylene diacrylate, diallyl maleate and methyl-m~thacrylate produced according to Example 26 of U.S.
Patent 4,096,202.
All evaluated compositions contained a nucleating amount of micro talc and a low level (less than 0.3 wt. %) of a stabilizing system not believed to affect the crystal-lization behavior of the compositions.
The lower degree of warpage observed for thecompositions containing the composite i~terpolymer is evidence that these compositions have improved or accelerated crystallization velocities. Thus, with appropriate tailoring of the part geometry and molding conditions, it is possible to obtain fully crystallized and therefore warpage-free parts at lower temperatures and with faster mold cycles than would be possible with compositions not containing this additive. The prior art has generally not recognized the possibility of molding into molds at temperatures significant-ly below 140C, particularly below 120C, and still obtaining highly crystalline parts not requiring further heat treatment.
Mo-2039-Ca -19-1 Trademark of Eastman Chemical Company Although the invention has been described in detail 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 spirit and scope of the invention except as it may be limited by the claims.
Mo-2039~Ca PC-52-II-Ca -20-., ... , ., __ ~, ~_-- - .
Claims (6)
1. A process for injection molding a thermoplastic composition comprising:
(a) intimately blending (i) from 70 to 98% by weight of a polyethylene terephthalate having an intrinsic viscosity of at least 0.3 dl/g measured as a 0.5% by weight solution in a 1:1 mixture of phenol and tetrachloroethane at 25°C; and (ii) 2 to 30% by weight of a multi-phase composite interpolymer comprising:
(A) about 25 to 95 weight percent of a first elastomeric phase polymerized from a monomer system comprising about 75 to 99.8% by weight C1 to C6 alkyl acrylate, 0.1 to 5% by weight crosslinking monomer, 0.1 to 5% by weight graftlinking monomer, said crosslinking monomer being a poly-ethylenically unsaturated monomer having a plurality of addition polymerizable reactive groups all of which polymerize at substantially the same rate of reaction, and said graftlinking monomer being a polyethylenically unsaturated monomer having a plurality of addition poly-merizable reactive groups, at least one of which polymerizes at a substantially different rate of polymerization from at least one other of said reactive groups;
and Mo-2039-Ca Pc-52-II-Ca (B) about 75 to 5 weight percent of a final, rigid thermoplastic phase which is polymerized in the presence of said elastomeric phase and which is free of epoxy groups; and (b) injection molding said blend into a mold held at a temperature of no more than 120°C and no less than 80°C, said molding temperature and the amount of interpolymer being selected to yield articles with crystallinities similar to those obtainable when the same article is molded from the same composition without the interpolymer at mold temperatures of 140°C.
(a) intimately blending (i) from 70 to 98% by weight of a polyethylene terephthalate having an intrinsic viscosity of at least 0.3 dl/g measured as a 0.5% by weight solution in a 1:1 mixture of phenol and tetrachloroethane at 25°C; and (ii) 2 to 30% by weight of a multi-phase composite interpolymer comprising:
(A) about 25 to 95 weight percent of a first elastomeric phase polymerized from a monomer system comprising about 75 to 99.8% by weight C1 to C6 alkyl acrylate, 0.1 to 5% by weight crosslinking monomer, 0.1 to 5% by weight graftlinking monomer, said crosslinking monomer being a poly-ethylenically unsaturated monomer having a plurality of addition polymerizable reactive groups all of which polymerize at substantially the same rate of reaction, and said graftlinking monomer being a polyethylenically unsaturated monomer having a plurality of addition poly-merizable reactive groups, at least one of which polymerizes at a substantially different rate of polymerization from at least one other of said reactive groups;
and Mo-2039-Ca Pc-52-II-Ca (B) about 75 to 5 weight percent of a final, rigid thermoplastic phase which is polymerized in the presence of said elastomeric phase and which is free of epoxy groups; and (b) injection molding said blend into a mold held at a temperature of no more than 120°C and no less than 80°C, said molding temperature and the amount of interpolymer being selected to yield articles with crystallinities similar to those obtainable when the same article is molded from the same composition without the interpolymer at mold temperatures of 140°C.
2. The process of Claim 1 wherein the composition to be injection molded contains 20 to 45 wt. % of glass fibers.
3. The process of Claim 1 wherein the mold is held at a temperature between 80 and 110°C.
4. The process of Claim 1 wherein the composite interpolymer has only two phases, the first phase comprising about 60 to 95 wt. % of said interpolymer and being polymerized from 95 to 99.8 wt. % of n-butyl acrylate, 0.1 to 2.5 wt. % of butylene diacrylate as a cross-linking agent and 0.1 to 2.5 wt. % of allyl methacrylate or diallyl maleate as a graftlinking agent and said final phase is polymerized from 60 to 100% by weight of methyl methacrylate.
5. A composition particularly suitable for injection molding into molds helt at temperatures less than 120°C comprising:
(a) 35 to 75 weight percent of a polyethylene Mo-2039-Ca -22-terephthalate having an intrinsic viscosity of at least 0.3 dl/g measured as a 0.5%, by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25°C;
b) 5 to 20 weight percent of a multiphase composite interpolymer comprising:
(A) about 25 to 95 weight percent of a first elastomeric phase polymerized from a monomer system comprising about 75 to 99.8%, by weight, C1 to C6 alkyl acrylate, 0.1 to 5%, by weight, cross-linking monomer, 0.1 to 5%, by weight, graftlinking monomer, said cross linking monomer being a polyethylenically unsaturated monomer having a plurality of addition poly-merizable reactive groups, all of which polymerize at substantially the same rate of reaction, and said graft-linking monomer being a polyethylenic-ally unsaturated monomer having a plurality of addition polymerizable reactive groups, at least one of which polymerizes at a substantially different rate of polymerization from at least one other of said reactive groups; and (B) about 75 to 5 weight percent of a final, rigid thermoplastic phase Mo-2039-Ca Pc-52-II-Ca which is polymerized in the presence of said elastomeric phase and which is free of epoxy groups; and (c) 20 to 45 wt % of glass fibers.
(a) 35 to 75 weight percent of a polyethylene Mo-2039-Ca -22-terephthalate having an intrinsic viscosity of at least 0.3 dl/g measured as a 0.5%, by weight, solution in a 1:1 mixture of phenol and tetrachloroethane at 25°C;
b) 5 to 20 weight percent of a multiphase composite interpolymer comprising:
(A) about 25 to 95 weight percent of a first elastomeric phase polymerized from a monomer system comprising about 75 to 99.8%, by weight, C1 to C6 alkyl acrylate, 0.1 to 5%, by weight, cross-linking monomer, 0.1 to 5%, by weight, graftlinking monomer, said cross linking monomer being a polyethylenically unsaturated monomer having a plurality of addition poly-merizable reactive groups, all of which polymerize at substantially the same rate of reaction, and said graft-linking monomer being a polyethylenic-ally unsaturated monomer having a plurality of addition polymerizable reactive groups, at least one of which polymerizes at a substantially different rate of polymerization from at least one other of said reactive groups; and (B) about 75 to 5 weight percent of a final, rigid thermoplastic phase Mo-2039-Ca Pc-52-II-Ca which is polymerized in the presence of said elastomeric phase and which is free of epoxy groups; and (c) 20 to 45 wt % of glass fibers.
6. The process of Claim 1, 2 or 3 wherein the composition comprises:
(a) 85 to 95 wt % of the polyethylene tere-phthalate, and (b) 5 to 20 wt % of the composite interpolymer, said weight percentages being based on the combined weight of polyethylene terephthalate and interpolymer.
Mo-2039-Ca Pc-52-II-Ca
(a) 85 to 95 wt % of the polyethylene tere-phthalate, and (b) 5 to 20 wt % of the composite interpolymer, said weight percentages being based on the combined weight of polyethylene terephthalate and interpolymer.
Mo-2039-Ca Pc-52-II-Ca
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US9527479A | 1979-11-19 | 1979-11-19 | |
| US095,274 | 1979-11-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1166781A true CA1166781A (en) | 1984-05-01 |
Family
ID=22251088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000363909A Expired CA1166781A (en) | 1979-11-19 | 1980-11-04 | Process for injection molding a rapidly crystallizing polyethylene terephthalate composition at reduced mold temperatures |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0029931B1 (en) |
| JP (1) | JPS5688458A (en) |
| CA (1) | CA1166781A (en) |
| DE (1) | DE3068718D1 (en) |
| ES (1) | ES496932A0 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3039114A1 (en) * | 1980-10-16 | 1982-05-13 | Bayer Ag, 5090 Leverkusen | THERMOPLASTIC POLYESTER MOLDS WITH IMPROVED TOUGHNESS |
| DE3117052A1 (en) * | 1981-04-29 | 1982-11-18 | Bayer Ag, 5090 Leverkusen | "AGING-RESISTANT, PROCESS-STABLE MIXTURES OF HIGH TOUGHNESS BASED ON THERMOPLASTIC POLYESTER" |
| DE3147881A1 (en) * | 1981-12-03 | 1983-06-16 | Basf Ag | HEAT-MOLDABLE FLAT SEMI-PRODUCT MADE OF FIBER-REINFORCED POLYETHYLENE TEREPHTHALATE |
| DE3336499A1 (en) * | 1983-10-07 | 1985-04-25 | Bayer Ag, 5090 Leverkusen | MOLDING MATERIALS FROM THERMOPLASTIC POLYESTER AND GRAFT RUBBER, METHOD FOR THE PRODUCTION THEREOF AND THEIR USE FOR THE PRODUCTION OF MOLDED BODIES |
| DE3733838A1 (en) * | 1987-10-07 | 1989-04-20 | Basf Ag | GLASS FIBER AMPLIFIED THERMOPLASTIC MOLDINGS BASED ON POYESTERS AND POLYMERPROPYLENE |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL6513222A (en) * | 1965-10-13 | 1965-12-27 | ||
| DE2444584C3 (en) * | 1974-09-18 | 1982-01-21 | Basf Ag, 6700 Ludwigshafen | Thermoplastic polyester molding compounds |
| DE2507776C2 (en) * | 1975-02-22 | 1983-09-22 | Bayer Ag, 5090 Leverkusen | Rapidly crystallizing poly (ethylene / alkylene) terephthalate |
| US4096202A (en) * | 1976-06-09 | 1978-06-20 | Rohm And Haas Company | Impact modified poly(alkylene terephthalates) |
| DE2659338A1 (en) * | 1976-12-29 | 1978-07-13 | Basf Ag | THERMOPLASTIC POLYESTER MOLDING COMPOUNDS WITH INCREASED THERMAL MOLD RESISTANCE |
| JPS53137251A (en) * | 1977-05-04 | 1978-11-30 | Mitsubishi Rayon Co Ltd | Reinforced resin composition having improved moldability |
| JPS5431456A (en) * | 1977-08-15 | 1979-03-08 | Toray Ind Inc | Thermoplastic resin composition |
| SE430168B (en) * | 1978-02-28 | 1983-10-24 | Du Pont | SUBSTANCE PACKAGING PLASTIC COMPOSITION CONTAINING REINFORCEMENT OR FILLER AND USE OF IT |
| US4212791A (en) * | 1979-02-23 | 1980-07-15 | Rohm And Haas | Poly(alkyleneterephthalate) molding compositions containing oligomeric polyester and segmented copolyester-polyether elastomer |
-
1980
- 1980-11-04 CA CA000363909A patent/CA1166781A/en not_active Expired
- 1980-11-06 DE DE8080106828T patent/DE3068718D1/en not_active Expired
- 1980-11-06 EP EP80106828A patent/EP0029931B1/en not_active Expired
- 1980-11-18 ES ES496932A patent/ES496932A0/en active Granted
- 1980-11-18 JP JP16148380A patent/JPS5688458A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ES8203041A1 (en) | 1982-03-01 |
| JPS6344043B2 (en) | 1988-09-02 |
| ES496932A0 (en) | 1982-03-01 |
| EP0029931A1 (en) | 1981-06-10 |
| JPS5688458A (en) | 1981-07-17 |
| EP0029931B1 (en) | 1984-07-25 |
| DE3068718D1 (en) | 1984-08-30 |
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