CA1333430C - Thermoplastic resin composition - Google Patents

Abstract

Disclosed is a thermoplastic resin composition which comprises [A] 100 parts by weight of a resin mixture consisting essentially of not less than 10 wt.% of polyarylate resin, not less than 20 wt.% of polyamide resin and 3 to 60 wt.% of poly-ethylene terephthalate resin, and [B] from 0.1 to 15 parts by weight of an epoxy resin of the following formula:

(wherein X is direct bond, lower alkylene, lower alkylidene, -SO2-, -O-, -S-, - - , -C(CN)2- or -

Description

~ 1- 72736-36D

This is a divisional application of Canadian Patent Application Ser. No. 613,801 filed September 27, 1988.

RACXGROUND OF TH~ INV~NTION
This invention relates to thermoplastic resin compositions which are mainly composed of polyarylate resins, polyamide resins and epoxy resins and have excellent impact strength, heat and solvent resistances and moldability.
Compositions made of polyarylate resins and polyamide resins have good heat and solvent resistances and good moldability. For instance, Japanese Patent Publication No.
56-14699 discloses a resin composition made of a polyarylate and a polyamide, and Japanese Laid-open Patent Application No. 52-100552 discloses a resin composition which is made of a polyarylate-based resin composed of a mixture of a polyarylate and polyethylene terephthalate, and a polyamide.
Since polyarylates and polyamides are substantially immiscible with each other, the composition obtained by melt kneading exhibits a phase separation structure wherein the adhesion strength at the interface between the polyarylate phase and the polyamide phase is so weak, with the attendant disadvantage of the resulted composition that the impact strength becomes small, thus leading to brittleness.
Attempts have been made to improve the impact strength of the resin compositions made of polyarylates and polyamides by addition, as the third ingredient, of a miscibility improver or an impact strength improver. For instance, in Japanese Laid-open Patent Application, there is used an N-substituted amido-containing polymer as the third ingredient. As the third ingredient, there are used polyalkylene phenylene esters containing a group of sulfonate salt in Japanese Laid-open Patent Application No. 59-105050, glycidyl group-containing olefin copolymers in Japanese Laid-open Patent - Application No. 61-183353, mixtures of epoxy group-containing ethylene copolymers and acid anhydride-containing olefin copolymer in Japanese Laid-open Patent Application Nos. 62-277462 and 62-283146.
However, the resin compositions disclosed in the Japanese Laid-open Patent Application Nos. 58-67749 and 59-105050 are far from satisfactory in improving the impact strength. With the resin compositions disclosed in the Japanese Laid-open Patent Application Nos. 61-183353, 62-277462 and 62-283146, the effect of improving the impact strength starts to develop when the content of the third ingredient exceeds about 5 wt%.
For obtaining satisfactory impact strength, the third ingredient has to be added in amount ranging from 10 to 30 wt%. Such resin compositions are unfavorably apt to undergo thermal decomposition in the cylinder of an extruder or injection molding machine, with attendant disadvantages such as gelation, coloration, a ~owering of mechanical strength, and defects in appearance of the resultant moldings such as flow mark, silver streak and silver blister.
Moreover, since olefin polymers are formulated in large amounts, the resulting resin compositions is improved in the impact strength but is considerably lowered with respect to the tensile strength, bending strength, modulus of elasticity and heat resistance.
A resin compositions made of a polyarylate resin, a polyethylene terephthalate resin and a polyamide resin has excellent heat and solvent resistances and moldability and is disclosed, for example, in Japanese Patent Publication No.
58-50260. However, this resin composition has such problems as involved in the compositions made of polyarylate resins and polyamide resins. More pa~ticularly, although polyarylates and polyethylene terephthalate are miscible with each other, polyamide is incompatible with these resins. The composition obtained by melt kneading of these resins exhibits a phase separation structure wherein the adhesion strength at the interface between the polyarylate and 1333~30 polyethylene terephthalate phases and the polyamide phase is weak, so that the composition has inconveniently a small impact strength and is brittle.
In order to improve the impact strength of the above composition, Japanese Laid-open Patent Application No. 52-100552 proposed an improved process, but satisfactory mechanical strength has not yet been obtained.
Japanese Patent Public Disclosure NQ. 187761/1987 discloses a thermoplastic resin composition comprising polycarbon-ate, poly(ester carbonate) and polyamide, in which bisphenol A
diglycidyl ether is contained as a compatibilizer having an epoxy group.
However, the composition disclosed in Japanese Patent Public Disclosure No. 187761/1987 is chiefly composed of poly-carbonate. Polycarbonate is decomposed easily by heat in the presence of even a small quantity of basic substance. In kneading process of polycarbonate and polyamide, therefore, polycarbonate is decomposed during thermal melting caused by the amide bond and terminal amino group of polyamide. In addition, since a monomer such as bisphenol A diglycidyl ether is used as the compatibilizer, it is difficult to knead such a liquid monomer with resins which are solid at normal temperatures.
SUMMARY OF THE INVENTION
An object of the invention is to provide a resin composition which has remarkably improved impact strength without a sacrifice of good solvent and heat resistances, good moldability, 1333~30 high rigidity and good thermal stability inherent to thermoplas-tic resin compositions predo~;~Antly made of polyarylates and polyamides.
According to the present invention, there is provided a thermoplastic resin composition which comprises:
[A] 100 parts by weight of a resin mixture consisting essentially of not less than 10 wt% of a polyarylate resin, not less than 20 wt% of a polyamide resin and from 3 to 60 wt% of polyethylene terephthalate resin; and [B] from 0.1 to 15 parts by weight of an epoxy resin of the following formula:

133~0 ~ ~ R I ~

C~ - CH-CH2-(-o ~ X ~ 0H

--~X~ o (whereln X represents a dlrect bond, a lower alkylene group havlng frou 1 to ~ carbon atou~, a lover alkylldene group havlng up to ~ carbon aton~, ;

-SO2-, -O- or -S-, where a part or all of the hydrogen atoms of X may be substituted with halogen atoms when X represents any hydrocarbon defined above, R's independently represent a hydrocarbon atom, a halogen atom, a lower alkyl group having from 1 to 4 carbon atoms, and n is an integer of 1 or over).
DETAILED DESCRIPTION OF THE INVENTION
The polyarylate resin used in the present invention is prepared from a bisphenol and/or its derivative, terephthalate acid and/or its derivative and isophthalic acid and/or its deri-vative and consists of these three ingredients.

- b - 72736-36D

Terephthalic acid and isophthalic acid have, respec-tively, the following formulae HOC ~ -COH ~ - COH
O O , O
HOC

The derivatives of terephthalic acid and isophthalic acid include acid halide compounds such as terephthalic acid dichloride, isophthalic acid dichloride and the like, and diester compounds such as dimethyl terephthalate, dimethyl isophthalate, diphenyl terephthalate, diphenyl isophthalate and the like.
Terephthalic acid, isophthalic acid and derlvatives thereof may be substituted, at part or all of the hydrogen atoms of the phenylene group, with a halogen atom or a lower alkyl group.
The bisphenols and derivatives thereof are represented by the following formula [2~

R R R R

HO ~ Y ~ OH [2]

R R

wherein Y represents a lower alkylene group havino fro~
1 to 4 carbon atoms, an alkylidene group having up to 4 carbon atoms, CN

-CH- -C-, CN

-SO2-, -O-, -S- or -C-, wherein part or all of the o hydrogen atoms in Y, if any, may be substituted with a halogen atom, and R's independently represent a hydrogen atom, a halogen atom or a lower alkyl group having from 1 to 4 carbon atoms.
Examples of the bisphenols of the formula [2] include 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)methane, 4,4'-dihydroxydiphenyl ether, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)ketone, bis(4-hydroxy-3-methylphenyl)methane, bis(4-hydroxy-3,5-dibromo-phenyl)methane, l,l-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxy-3-methyl-phenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl) propane, 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane, 2,2-bis (4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxyphenyl) butane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl) diphenylmethane, bis(4-hydroxyphenyl)difluoromethane and the like.
Of these, 2,2-bis(4-hydroxyphenyl)propane which is usually called bisphenol A is preferred because of the ease in availability of starting materials. If necessary, a small amount of aromatic dihydroxy compounds such as, for example, 4,4'-bisphenol, 2,6-: 1333~30 naphthale~ediol, hydroquinone, chlorohydroquinone and the like, may be used in combination with the bisphenols.
The polyaryl resins may be prepared by any methods including an interfacial polymerization method, a solution poly-merization method and a melt polymerization method.
The polyamide resins used in the present invention are those of the following general formula, ~ C - R - NH t or t C - R - C - N H - R3 - NH t ll ll ll O O O
wherein Rl, R2 and R3 are independently an alkylene group having from 2 to 16 carbon atoms, and are prepared by condensation reaction between diamines and dibasic acids, self-condensation of amino acids, or ring opening polymerization of lactams.
For instance, there can be mentioned nylon 6 prepared from ~-caprolactam or ~-aminocaproic acid, nylon 6-6 prepared from hexamethylenediamine and adipic acid, nylon 6-10 prepared from hexamethylenediamine and sebacic acid, nylon 6-12 prepared from hexamethylenediamine and dodecanoic acid, nylon 11 prepared from ~-aminoundecanoic acid, nylon 12 prepared from ~-laurolactam or ~-aminododecanoic acid, nylon 4-6 prepared from 1,4-diamino-butane and adipic acid, and the like. In view of the easy avail-ability of the starting materials, nylon 6 and nylon 6-6 are preferred.
The epoxy resin used in the present invention is re-presented by the following general formula:

1333~30 R R R R

C ~ /CH CH2-~ ~ X ~ OCH21HCH2 t~n R R R R

R R R R

-O--~X_~OCH2CH fH2 [1]

R R R R

wherein X represents a direct bond, a lower alkylene group having from 1 to 4 carbon atoms, an alkylidene group having up to 4 carbon atoms, ,~

-CH- CN ~
--C-- --C--, CN

-S02-, -O-, or -S- wherein part or all of the hydrogen atom~ of X may be substituted with halogen atoms when X
represents any hydrocarbon defined above, R's independently re-present a hydrogen atom, a halogen atom, a lower alkyl group having from 1 to 4 carbon atoms, and n is an integer of 1 or over. This epoxy resin is obtained by a bisphenol and an epihalohydrin such as epichlorohydrin. Examples of the bisphenol are those of the formula [2] set forth above with respect to the polyarylate resin.
Of these, 2,2-bis(4-hydroxyphenyl)propane or bisphenol A is preferred because of the ease in availability of the starting materials.
In the formula ~1], n which indicates the number of the repeating units in the formula should be 1 or over. If n is equal to zero, the adverse influence of the terminal epoxy group is apt to develop, with the tendency that the resultant resin composition is gelled, colored or decomposed. Especially, the melting temperature and viscosity increase considerably and thus, the molding becomes difficult. In order to bring out the effect of satisfactorily improving the impact strength, it is preferred that the terminal epoxy groups and the repeating polyether polyol units are present at an appropriate ratio. In this sense,a pre-ferred range of n is up to 28, more preferably from about 6 to 20.
A preferred range of epoxy equivalents is from about 1000 to 3000 for bisphenol A-type epoxy resins.
The epoxy resins used in the present invention may contain, as copolymerized, a small amount of diols other than bisphenols, including aromatic diols such as 2,6-naphthalenediol, hydroquinone and the like, and aliphatic diols such as 1,4-butanediol, propylene glycol, ethylene glycol and the like.
The polyethylene terephthalate resin used in the invention is one which is prepared, by any known technique, from terephthalic acid and/or its derivative and ethylene glycol.
The polyarylate resin, polyethylene terephthalate resin and polyamide resin are, respectively, used in amounts of not less than 10 wt%, from 3 to 60 wt%, and not less than 20 wt%, 1333~3~

_ each based on the total amount of these three resins. If the amount of the polyarylate resin is less than 10 wt%, the heat resistance and impact strength of the resultant resin composition become low. If the amount of the polyamide resin is less than 20 wt%, the moldability and solvent resistance are lowered. If the amount of the polyethylene terephthalate resin is less than 3 wt%, the moldability and rigidity (modulus of elasticity) of the resultant composition are lowered. Over 60 wt%, the heat resis-tance and impact strength are lowered.
An increasing amount of the polyarylate component results in an increase in the impact strength and heat resistance of the resultant composition. When the polyamide component in-creases in amount, better moldability and solvent resistance are obtained. If the polyethylene terephthalate component increases in amount, the moldability becomes better with an increase in rigidity. A preferable composition capable of imparting well-balanced properties such as heat resistance, impact strength, moldability, rigidity and solvent resistance comprises from 15 to 45 wt% of the polyarylate resin, from 45 to 65 wt% of the poly-amide resin, and from 7 to 35 wt% of the polyethylene terephthalate.
The amount of the epoxy resin is generally in the range of from 0.1 to 15 parts by weight per 100 parts by weight of the mixture of the polyarylate resin, polyamide resin and poly-ethylene terephthalate resin. If the amount is less than 0.1 part by weight, the impact strength is not improved satisfactorily.
Over 15 parts by weight, the resultant composition lowers in heat 133~130 ~ - 12 - 72736-36D

resistance, and the melting temperature and viscosity increase, making it difficuIt to mold such a composition. A preferable amount is in the range of from 2 to lO parts by weight.
For the production of the composition of the inven-tion, any method of melt kneading the polyarylate resin, the polyamide resin, polyethylene terephthalate and the epoxy resin may be used without limitation. For instance, the melt kneading may be carried out by use of a two-roll mill, Banbury mixer, single-screw extruder, twin-screw extruder and the like. Alter-natively, while kneading in an in]ection molding machine, the composition may be molded. Preferably, the single or twin-screw extruder of the high kneading type is used for kneading and molding. The kneading order of the respective ingredients for obtaining the composition of the invention is not critical. For instance, the polyarylate, polyamide, polyethylene terephthalate and epoxy resin may be simultaneously kneaded. Alternatively, two or more of the four components may be first kneaded, to which the other components are subsequently added. The optimum kneading order is such that the polyarylate and polyethylene terephthalate are first melt kneaded, followed by melt kneading the mixture, polyamide and epoxy resins.
Additives and/or fillers may be further added to the resin composition of the invention. The additives may be anti-oxidants and thermal stabilizers such as copper halides, hindered phenols and the like, phosphorus working stabilizers, benzo-triazole and hindered amine light stabilizers, plasticizers such 1333~30 as paraffins, higher fatty acids and esters thereof, metal salts and the like, lubricants such as silicone resins, fluorine resins and the like, flame retardants such as decabromodiphenyl ether, tetrabromobisphenol A, tetrachlorobisphenol A, aluminium hydroxide, antimony trioxide, ammonium phosphate, tricresyl phosphate, triethyl phosphate and the like, pigments, dyes and the like. The fillers may be talc, calcium carbonate, mica, wollastonite, ferrite, magnet powder of rare earth elements, glass fibers, carbon fibers, asbestos fibers, metallic fibers, aramide fibers, potassium titanate whiskers, and the like.
EXAMPLES
The present invention is more particularly described by way of example, which should not be construed as limiting the present invention. Comparative examples are also shown.
First, starting materials used in the examples and comparative exampes are illustrated.
1. Polyarylate resin PAR-l: polyarylate resin obtained from a 1:1 mixture of terephthalic acidand isophthalic acid and bisphenol A(U-Polymer U-100, available from Unichika ~o., Ltd.). The inherent viscosity was 0.65 when determined using a solvent of phenol and tetrachloroethane at a ratio by weight of 60:40 at a concentra-tion of 0.25 g/dl at 23C.
2. Polyamide resins (PA-l to PA-2) PA-l: nylon 6 (Amiran** CM1017, available from Toray Limited).

**Trade-mark 1333~30 PA-2: nylon 6-6 (A~iran CM3001, available from Toray Limited).
3, Third Ingredients (CP-l to CP-8) CP-l to CP-6: epoxy resins (available from Danippon Ink and Chemicals, Inc.).
CH

CH~ - CHCH2 ( -CH2-~HCH2 )n ~ C -~ OCH2 CH / CH2 Abbrevia- Commercial Epoxy Approximate Melting tion Name Equiva- Number of n Point lent* (C) CP-l Epichlon**840180 n - 0 liquid~900 poises at 25C) CP-2 Epichlon 1050450 n - 2 70 CP-3 Epichlon 4050955 n ~- 5 - 6 102 CP-4 Epichlon 70501809 n - 12 130 CP-5 Epichlon 90552600 n - 17 152 CP-6 Epichlon 91554070 n - 28 155 **Trade-mark 1333~3~
_, *) The epoxy equivalents in the epoxy resin was quantitatively determined by titration with perchloric acid to obtain the weight (g) of the resin per equivalent of the epoxy group.
CP-7: phenoxy resin (phenoxy PKHH, available from Union Carbide Co., Ltd.) H3 :H~-:HCH2 ~o ~ .
~H ~H ;H, :H~
._ OCH2;HCH2 ~tnO~J
~H HJ
OCH2CHCH~
~_v~ I ~ n T 1 0 0 OHOH
CP-8: Epichlon 9055 whose terminal epoxy groups were modified with diethanolamine (HOCH2CH2)2N-CH2:HCH2 1~0 ~H
H. ~ .H~
_ ~ OCH2,HCH2 ~no ~ J ~ OCH2:HCH2-N(CH2CH20H)2 :HJ ~H ,HJ ~N
n ~ 1 7 4. Polyethylene terephthalate resin (PE-1) (PET resin TR-4550BH, available from Teijin Co., Ltd.).
The inherent viscosity was 0.70 as determined in the same manner as with the polyarylate.
The physical properties were evaluated according to the following methods.
1) Tensile test:the measurement was made according to ASTM D-638 at a pulling speed of 50 mm/minute to determine a tensile break strength, a tensile modulus and a tensile break energy (energy required before breakage).

`~ - 16 - 72736-36D

2) Izod impact test: th.e measurement Was m.ade according to ASTM D-256 using a thickness of 1/8 inch.es as notchéd.
3) Heat distortion tempera.ture: after annealing at 150 QC
for 3 hours, the measurement was made according to ASTM D-648 at a thickness of 1/8 inches at a load of 18.6 kg.cm2.
4) Temperature at which the melt viscosity reaches 10,000 poises: the Koka-type flow tester CFT-500, made by-Shimadzu Corporation, was ùsed to successively measure the vis-cosity of resin by the use of a 0.5 mm~ x 1.0 mm nozzle under conditions of a load of 10 kg and a heating rate of 6C/minute thereby determining a temperature at which the melt viscosity reaches 10,000 poises. This is a kind of criterion for moldability of the resin and a criterion for the degree as to how the gelation reaction proceeds. More particularly, when. the tempera.ture is lower, a less degree of gelation proceeds with more ea.se in molding.
Examples 1 to 6 and Comparative Examples 1 and 2 60 parts by weight of a polyarylate resin (PAR-l) and 40 parts by weight of a polyethylene terephthalate resin (PE-l) were mixed and dried at 110C for 5 hours. Thereafter, the mixture was melt kneaded and pelletized by means of a twin.-screw extruder at a cylinder temperature of 300C. 50 parts by weight of the mixture of the polyarylate resin and polyethylene terephthalate resin and 50 parts by weight of nylon 6 (PA-1) were mixed, to which an epoxy resin (CP-5) was added in different amount per 100 parts by weight of this mixture. ~fter drying the respective mixtures, each mixture was melt kneaded and pelletized 1333~30 ~ - 17 - 72736-36D

by means of a twin-screw extruder at a cylinder temperature of 270C. The resultant pellets were molded by means of an injection molding machine into l/2 x 1/5 x ll8 inch elongated test pieces and dumbbell specimens for ASTM tensile test. The physical properties of the respective moldings were evaluated. The results are shown in Table 1.
From Table 1, it wiIl be seen that the addition of small amounts of the epoxy resin results in a remarkable increase in the Izod impact strength and the tensile break energy. However, when the content of the epoxy resin exceeds 15 parts by weight, not only the impact strength and the heat distortion temperature are lowered, but also the moldability is worsened.
Examples 7 to 11 and Comparative Examples 3 to 8 A polyarylate resin (PAR-l), a polyethylene terephthal-ate resin (PE-l), nylon 6 (PA-l) and an epoxy resin (CP-5) were mixed in different mixing ratios indicated in Table 2, followed by pelletization in the same kneading order and manner as in Ex-ample 1, injection molding and evaluation of the physical proper-ties. The results are shown in Table 2.
Examples 12 to 18 and Comparative Examples 9 to 13 Starting materials at different mixing ratios as indicated in Table 3 were pelletized in the same manner as in Example 1 wherein the polyarylate resin and polyethylene terephthal-ate were initially melt kneaded, to which the other two ingredients were added and melt kneaded for pelletization, followed by in-~ection molding and evaluation of the physical properties. The results are shown in Table 3.

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The resin composition according to the present invention has especially good moldability, heat resistance, impact strength, solvent resi~tance and high rigidity and are thus well balanced in the physical properties. When making use of these characteristic features, the resin composition of this aspect has utility optimumly a~ plastics for outer plates of automobile having the capability of paint baking, switches, knobs, housings of electronic and electric instruments which are exposed to intense heat, containers and housing instruments which are exposed to chemical compounds.

Claims (8)

1 A thermoplastic resin composition which comprises, [A] 100 parts by weight of a resin mixture consisting essentially of not less than 10 wt% of a polyarylate resin, not less than 20 wt% of a polyamide resin and from 3 to 60 wt% of polyethylene terephthalate resin and [B] from 0.1 to 15 parts by weight of an epoxy resin of the following formula:

(wherein X represents a direct bond, a lower alkylene group having from 1 to 4 carbon atoms a lower alkylidene group having up to 4 carbon atoms, -SO2-, -O- or -S-, where a part or all of the hydrogen atoms of X may be substituted with halogen atoms when x represents any hydrocarbon defined above, R's independently represent a hydrogen atom, a halogen atom, a lower alkyl group having from 1 to 4 carbon atoms, and n is an integer of 1 through 28).

2. A thermoplastic resin composition according to Claim 1, wherein in the formula [1], n is from 6 to 20.

3. A thermoplastic resin composition according to claim 1, wherein the amount of the polyarylate resin is from 15 to 45 wt% based on the resin mixture, the amount of the polyamide resin is from 45 to 65 wt% based on the resin mixture and the amount of polyethylene terephthalate resin is from 7 to 35 wt% based on the resin mixture.

4. A thermoplastic resin composition according to claim 3, wherein the epoxy resin is contained in an amount of from 2 to 10 parts by weight per 100 parts by weight of the resin mixture.

5. A thermoplastic resin composition according to claim 3, wherein n in the formula [1] is an integer of 6 to 20.

6. A thermoplastic resin composition according to any one of claims 1 to 5, wherein:
the polyarylate resin is composed of (a) a unit derived from a bisphenol of the formula:

[2]

(wherein Y represents an alkylene group having 1 to 4 carbon atoms, an alkylidene group having up to 4 carbon atoms, , -SO2-, , , -O-, -S- or -CO-, wherein part or all of hydrogen atoms in Y if any may be substituted with a halogen atom, and R's independently represent a hydrogen atom, a halogen atom or an alkyl group having to 4 carbon atoms), (b) a unit derived from terephthalalic acid in which a part or all of hydrogen atoms of the phenylene group may be substituted by a halogen atom or a lower alkyl group, and (c) a unit derived from isophthalic acid in which a part or all of hydrogen atoms of the phenylene group may be substituted by a halogen atom or a lower alkyl group; and the polyamide resin is composed of a repeating unit represented by the formula:
, or (wherein R1, R2 and R3 are independently an alkylene group having 2 to 16 carbon atoms).

7. A thermoplastic resin composition according to claim 6, wherein:
the polyarylate resin is composed of (a) a unit derived from bisphenol A, (b) a unit derived from terephthalic acid and (c) a unit derived from isophthalic acid; and the polyamide is nylon 6, nylon 6-6, nylon 6-10, nylon 6-12, nylon 11, nylon 12 or nylon 4-6.

8. A thermoplastic resin composition according to claim 6, wherein the epoxy resin [B] is derived from bisphenol A.