CA1196129A - Thermoplastic resin composition - Google Patents

Abstract

Abstract The invention provides a thermoplastic resin composition which comprises (A) a polycarbonate resin, (B) a rubber modified copolymer, and (C) an epoxy group-containing olefin copolymer. The composition has desirable physical properties and, in particular, has improved weld strength.

Description

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Thermoplastic resin composition The present invention relates to thermoplastic resin compositions, More particularly, it relates to thermo-plastic resin compositions comprising polycarbonate resins and having good physical properties such as impact resistance and heat resistance wi~h improved weld strengthO
Polycarbonate resins have excellent physical properties, in particular high impact resistance and heat resistance, and are known as 'lengineering plas~icsl'. It is also known that various other re~ins can be blended with polycarbonate resins for enhancing the physical properties of the polycarbonate resins and or improving their deterioration resistance. Fox instance, incorpora-tion of ABS resins (acrylonitrile-butadiene-styrene copolymer), MBS resins (methyl methacrylate~butadiene-s~yrene copolymer) or ABSM resins (acrylonitrile-butadiene-styrene-methyl methacrylate copolymer) into polycarbonate resins is effective for improving their moldabillty and reducing the thickness dependency of impact resistance (Japanese Patent Publns. (examined) Nos. 15225/1963, 71/64, 11496/67 and 11142/76). Further, for instance, incorporation of AES resins (acrylonitrile-ethylene/
propylene rubber-styrene copolymer3 into polycarbonate resins i~ effective for improving their weather re~istance and stain resistance (Japanese Patent Publn. (unexamined) No. 48547/1973J.

In injection molding, which is the most popular mold-ing procedure, the number of gates and the flow state of t~e resin must be changed according to the form and size of the desired product. For this reason, resin flowing in different directions usually unavoidably comes into contact, thus forming weld parts. The weld part of a molded product made of a conventional thermoplastic resin composition comprising a polycarbonate resin containing a rubber modified copolymer is usually insufficient in strength, and this is a great drawback for practical use of the resulting products.
As a result o~ extensive study, it has now been found that the incorporation of an epoxy group-containing olefin copolymer into a thermoplastic resin composition compris-ing a polycarbonate resin and a rubber modified copolymer affords a resinous composition having good physical proper-ties such as impact resistance and heat resistance with improved weld strength.
According to this invention, there is provided a thermoplastic resin compo6ition which comprises (A) a polycarbonate resinr (B) a rubber modified copolymer, and (C) an epoxy group-containing olefin copolymer.
Examples of the polycarbonate resin used as component (A) are aliphatic polycarbonates, aromatic polycarbonates, aliphatic-aromatic polycarbonates, etc. Usually, polymers and copolymers of bisphenols, e.g. bis(4-hydroxyphenyl) alkanes/ bis(4-hydroxyphenyl)ethers, bis(4-hydroxyphenyl) sulfones, bis(4-hydroxyphenyl)sulfides and bis(4-hydro~y-phenyl)sul~oxides, and~or halogenated bisphenols are employed. T~pical examples of the polycarbonate resins and their production are described in various textbooks and literature references including the Encyclopedia of Polymer Science and Technology, Vol. 10, pages 710 to 764 (1969).
The rubber modified copolymer used as component (B) can be obtained by pol~merizing at least two kinds of monomers chosen from aromatic vinyl compounds, vinyl cyanides and alkyl esters of unsaturated carboxylic a~ids in the presence of rubbers. The resulting product com-prises (b-l) a copolymer comprising units of the rubber and units of the monomers graf~ polymerized thereon (hereinafter referred to as the "graft copolymer") usually with (b-2) a copolymer comprising unit~ of the monomers (hereinafter referred to as the "copolymer"). Alterna-tively, the graft copolymer (b-l) and the copolymer (b-2) may be separately produced and combined together to form a uniform composition which can be used as component (B).
In general) the rubber modified copolymer (B~ comprises the graft copolymer ~b-l) and the copolymer (b-2) respec-tively in amounts of lO to 100 % by weight and of 90 to 0 % by weight on the basis of the total weight of the rubber modified copolymer ~Bj. When the content of the graft copolymer (b-l) is le~s than 10 ~ by weight, the ultimate coposition has insufficient impact resistance.
The weight proportion o the rubber and the monom~rs in the graft copolymer (b-l) is normally from 5 ~ 95 ko 70 : 30. the composition of the monomers is not limited and may comprise, for instance~ an aromatic vinyl compound(s) in a content of 50 to 80 ~ by weight and a vinyl cyanide(s) and/or an alkyl ester of unsaturated carboxylic acid(s) in a content of 50 to 20 % by weight. NQ particular restric-tion is present on the particle size of the graft copolymer (b-l), but it is usually from 0O05 to S microns, preferably from 0.1 to 0.5 microns.
The composition o the monomers in the copolymer (b-2) is also not limited and may comprise, Eor example, an arom-atic vinyl compound(s) in a content of 50 to 90 % by weight and a vinyl cyanide(s) and/or an alkyl ester of unsatur-ated carboxylic acid ~5) in a content of 50 to lO ~ by weight. No special limitation is present on the in~rinsic viscosity of the copolymer (b-2), and it is usually from 0.60 to 1.50 (when determined in dimethylformamide at 30C).

Examples of the rubber for the grat copolymer (b-l) are polybutadiene, styrene/butadiene copolymer, acrylo~
nitrile/butadiene copolymer, ethylene/propylene copolymer, ethylene/propylene/non-conjugated diene copolymer (e.g.
dicyclopentadiene, ethylidenenorbornene, 1,4-cyclohexa-diene, l,4-cycloheptadiene, 1,5-cyclooctadiene~, ethylene/
vinyl acetate copolymer, chlorinated polyethylene, poly-alkyl acrylate~ etc. When the ethylene/propylene copoly-mer of the ethylene/propylene/non-conjugated diene copolymer are employed/ the molar ratio of ethylene and propylene may be from 5 : 1 to 1 O 3~ The non-conjugated diene content in the ethylene/propylene/non-conjugated diene copolymer is preferably from 2 to 50 in terms of the iodine value. Examples of the aromatic vinyl compound(s) are styrene, ~-methylstyrene, methyl-~-methylstyrene, vinyltoluene, monochlorostyrene, etc~ Examples of the vinyl cyanide(s) are acrylonitrile, methacrylonitrile, etc. Examples of the alkyl ester of unsaturated car-boxylic acid(s) are alkyl acrylates (e.g. methyl acrylate, ethyl acrylatel butyl acrylate)y alkyl methacrylates ~e.g~
methyl methacrylate, ethyl methacrylate, butyl methacryl-ate), hydroxyalkyl ~crylates (e~g~ hydroxyethyl acrylate, hydroxypropyl acrylate), hydroxyalkyl methacrylate (e.~.
hydroxyethyl methacrylate, hydroxypropyl methacrylate), etc.
Any conventional polymerization procedure may be adopted for the preparation of the rubber modified copolymer (B) such as emulsion polymerization, suspension polymerization, bulk polymerization, solution polymer-ization, emulsion-su~pension polymerization and bulk~
suspension polymerization.
In the thermoplastic composition of the invention, the wei~ht proportion of the polycarbonate re~in (A) and the rubber modified copolymer ~B) may be from 10 : 90 to 90 :
10. When the content of the polycarbonate resin (A) i5 smaller than the lower limit, the heat resistance and the weld strength are much reduced. When the content is larger than the upper limit, the moldability is remarkably reduced. In addition, the appearance deteriorates to the extent that the product is not suitable for practical use.
The epoxy group-containing oleEin copolymer (C) is a copolymer of at least one unsaturated epoxy compound and at least one olefin with or without at least one ethylen-ically unsaturated compound. While no special limitation is present on the relative proportions o these monomers, the content of the unsaturated epoxy compound(s) is preferably from 0O05 to 95 ~ by weight.
Examples of the unsaturated epoxy compound(s) are those having an unsaturated group copolymerizable wi~h an olefin and an ethylenically unsaturated compound as well as an epoxy group in the molecule. For example, unsat-urated gly~idyl esters, unsaturated glycidyl ethers, epoxyalkenes, p-glycidylstyrénes, etc. are suitable.
Those of the following formulas are also suitable:
O
R-C-O-CH2-CH-CH2 (I) o R-X-CH CE~-CH (II) ~ ~ ~ 2 o R' R-C-CH (III) ~of 2 wherein R i5 a C2-C18 hydrocarbon group having an ethylenic unsaturation, ~' is a hydrogen atom or a methyl group and X is -CH2O-, ~ O- or - ~ . More specifically, the following compounds are examplified.
glycidyl acryl~te, glycidyl methacrylate, glycidyl itaconate, butenecarboxylates, allyl glycidyl ether,

2-methylallyl glycidyl ether, styrene-p-glycidyl ether, 3S 3,4-epoxybutene, 3r4-epoxy-3-methyl-l~butene, 3,4-epoxy-l~penteneO 3,4-epoxy-3-methylpentene r 5,6 epoxy-l-hexene, vinylcyclohexene monoxide, p-glycidylstyrene~ etc.

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Examples of the olefin(s) a~e ethylene, propylene, butene 1, 4-methylpentene-1, etc.
Examples of the ethylenically unsaturated compound(s), are olefins, vinyl esters having a C2~C6 saturated carboxylic acid moiety, acrylic and methacrylic esters having a Cl-C8 saturated alcohol moiety, maleic esters having a Cl C8 saturated alcohol moiety, vinyl halides~
vinyl ethers~ N-vinyllactams, carbonamides, etc. These ethyleneically unsaturated compounds may be copolymeriæed with the unsaturated epoxy compounds and the olefins in an amount of not more than 50 % by weight, especially from 0.1 to 45 ~ by weight, based on the total weight of the monomers to be copolymerized.
The epoxy group-containing olefin copolymer ~C) may be prepared by various procedures, of which one typical example comprises contacting an unsaturated epoxy compound and an olefin with or without an ethylenically unsaturated compound with a radical generating agent at a temperature of 40 to 300C under a pressure of 50 to 4000 atm. Another typical example comprises irradiating a mixture of poly propylene and an unsaturated epoxy compound with gamma rays under a high vacuum.
No particular restriction is present on the amount of the epoxy group-containing olefin copolymer ~C~ to be incorporated in the mixture, and the amount is usually rom 0.1 to 40 parts by weight to 100 parts by weight of the total weight of the polycarbonate resin ~A) and the rubber modified copolymer (B). When the amount is less than the stated lower limit, a satisfactory dispersibili~y is not assured. When more than the upper limit, layer separation is apt to ~e produced in the molded product.
To produce desirable impact strength/ weld strength and processability of the thermoplastic resin composition, an amount of from 0~5 to 10 parts by weight is particularly preferable.
For the preparation of the thermoplastic resin compos-ition of the invention, the said essential components may be mixed together in any optional order. For exarnple, all of ~hem may be mixed together at the same time. Further, ~or example, two of them may be first mixed together, followed by introduc~ion of the remaining one into the resultant mixture Mixing may be achieved by the use of any conventional mixing apparatus eOg. a banbury mixer, a monoaxial extruder or a biaxial extru~erO If desired, another resin, e.g. a polyolefin resin (e.g. polyethylene~
polypropylenel ethylene/propylene copolymer) and/or additive(s) e.g. dyestuffsr pigmentsl stabilizers, plas-ticizers, antistatic agents, ultraviolet ray absorbers, flame retardant agents, lubricants and fillers, may be incorporated into ~he thermoplastic resin composition.
Practical and presently preferred embodiments ~f the invention are illustratively shown in the following Examples wherein ~ and part(s) are by ~eight unless otherwise indicated.
Examples 1 to 10 and Comparativ2 Examples 1 to 7 According to the formulation as shown in Table 1 or 2, the polycarbonate resin (A), the rubber modified copolymer (B) and the epoxy group-containing olefin copolymer (C) or polyethylene were mixed together to form a thermoplastic resin composition, of which the physical properties are also shown in Table 1 or 2.
The polycarbonate resin (A~ and the polyethylene resin employed were the commercially available materials. The rubber modified copolymer (B) and the epoxy group-contain-ing olefin copolymer (C) were prepared as set forth here-inbelow.
Polycarb~nate resin (A):-"Panlit L-1250W" manufactured by Teijin Chemical.
Rubber modified copolymer (8) (No~
Graft copolymer (b-l) Polybutadiene (~el content, ~0 %) (~0 parts (in ~erms of solid)~/ potassium persulfate (0.5 part), potassium olefinate (0.5 part) and dodecylmercaptan ~0.5 part) were ~ ~3~~

mixed together, styrene (36 parts) and acrylonitrile (14 parts) were added thereto, and polymerization was carried out at 70C for 3 hours~ followed by aging for 1 hour.
The reaction mixture was subjected to salting out, dehydra-tion and drying to give a graft copolymer of 0.3 to 0.4 micron in particule size.
Copolymer (b-2) To a mixture of styrene (70 parts) and acrylonitrile (30 parts), t-dodecylmercaptane 50.1 part) was added, and the resultant mixture was subjected to pre-polymerization in a bulk state at 90C for 3 hours. Water (210 parts), methylcellulose (1.0 part) and benæoyl peroxide (0.3 part) were added theretoD The resulting aqueous dispersion was heated from 30C to 90C, and polymerization in a disper-sion state was carried out for 10 hours. Removal of the water gave a copolymer having an intrinsic viscosity of 0.50 (when determined in dimethylformamide at 30C).
Rubber modified copolymer ~B) (No~ 2):-Graft copolymer (b-l~
Ethylene/propylene/non-conjugated diene copolymer (EPDM) (iodine value, 8~5; Mooney viscosity, 61, propylene content, 43 % by weight; non-conjugated diene component, ethylidenenorbornene) (150 parts) was dissolved in a mixture of n-hexane (3000 parts) and dichloroethylene (1500 parts). Styrene (300 parts3, acrylonitrile (150 parts) and benzoyl peroxide ~11 parts) were added thereto, and polymerization was carried out at 65C for 10 hours in nitrogen atmosphere. The reaction mixture was con~ac~ed with a greatly excessive amount o~ methanol. The precipit 3Q ate was collected by filtration and dried to give a graft copolymer (rubber content, about 24 %).
Copolymer (b-2) To a mixture of styrene (70 parts) and acrylonitrile (30 parts), t-dodecylmercaptane (0.1 part) was addedy and the resultant mixture was subjected to pre-polymerization in a bulk state at 90C for 3 hours. Water (210 parts), methylcellulose ~1~0 part) and benzoyl peroxide (0.3 part) were added thereto. The resulting aqueous dispersion was heated from 30C to 90C, and polymerization in a disper-sion state was carried out for 10 hours. Removal of the water gave a copolymer having an intrinsic viscosi~y o~
0.50 (when determined in dimethylformamide at 30C).
Epoxy group-containing olefin copolymer (C):-Into an autoclave, compressed ethylene (2000 kg/cm~),glycidyl methacrylate and vinyl acetat~ were charged together with di-t-butyl peroxide as a catalyst, and the mixture was stirred at 150 to 300C for several minutes while stirring, whereby bulk-polymerization proceeded.
The reaction mixture was passed through a separator to collect an epoxy group-containing olefin copolymerO
Polyethylene res~n:~
"Sumika~hen Har ~ 2703" manufactured by Sumitomo Chemical.
The weld strength was determined as follows:
A melted resin (200C) was injected from two gates (each being 2.5 x 2.0 mm) having a gate distance of 100 mm to make a test piece 15G mm long, 150 mm wide and 3 mm high. The test piece was placed on a cylinder of 120 mm in inner diameter, 126 mm in outer diameter and 80 mm in height. A steel ball of 1 kg was dropped onto the central part of the test piece in a room kept at -30~C, and the maximum energy (kg~cm) that could be absorhed without the test piece breaking was measured.

Table 1 Example Comparative Example Test No. ~ ~

Polycar~onate resin ~Aj 40 50 50 60 70 50 60 50 (part(s)) Rubber modified copolymer (B) (No. 1) (part(s)J
Graft copolymer (b-l) 25 30 15 20 lG 30 20 30 Copolymer (b-2~ 35 20 35 20 20 20 20 20 Epoxy group-containin~
olefin copolymer (C) (part(s)) E-GMA-VA*l) 3 - 3 - 2 - - -E-GMA*2~ - 2 - 1.5 - - - -Polyethylene ~part(s)j ~ 3 Weld strength (DuPcnt~200~20G 190~ 200 180 20 25 45 impact strength at weld llne) ~-3QCC) (kg.cm) Notched Izod impact 48~656.6 4~.5 52.0 51.0 55.0 56O3 53.2 s~rength (20C3 (k~.cm/cm2~
Heat distortion tempera-100.5 105.0106.0108.711203105.2 106.5 105.8 ture (264 psi~ no annealing) ( C) Processability (Koka-type0~51 0.50 0~55 0.480.420.50 0.56 0.58 flow tester, ~30Cs 60 kg~cm~) (ml/m7 n) F~exural modulus~ x 104 2.0 2.1 2.2 2~15 20 5 2~1 2.2 2.05 ( kg/cm2 ) Note: *1~ Ethylene/glycidyl methacrylate/vinyl acetatQ copolymer (90 : 7 : 3)O
*2~ Ethylene/glycidyl methacrylate copolymer (90 : 10).

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Claims (5)

Claims:

1. A thermoplastic resin composition having good weld strength, which comprises (A) a polycarbonate resin, (B) a rubber modified copolymer and (C) an epoxy group-containing olefin copolymer.

2. A composition according to claim 1, wherein the rubber modified copolymer (B) comprises a copolymer obtained by polymerizing at least two kinds of monomers chosen from aromatic vinyl compounds, vinyl cyanides and alkyl esters of unsaturated carboxylic acids in the presence of at least one rubber chosen from conjugated diene rubbers and ethylene-propylene rubbers.

3. A composition according to claim 1, wherein the weight proportion of the polycarbonate resin (A) and the rubber modified copolymer (B) is from 10 : 90 to 90 : 10.

4. A composition according to claim 1, wherein the amount of the epoxy group-containing olefin copolymer (C) is from 0.1 to 40 parts by weight to 100 parts by weight of the composition.

5. A composition according to claim 1, wherein the amount of the epoxy group-containing olefin copolymer (C) is from 0.5 to 10 parts by weight to 100 parts by weight of the composition.