CA1057445A

CA1057445A - Thermoplastic resin composition

Info

Publication number: CA1057445A
Application number: CA000213427A
Authority: CA
Inventors: Kazuhiko Motomatsu; Mikio Hirai; Masayoshi Morimoto; Isao Yoshida; Katsuji Abe
Original assignee: Sumitomo Chemical Co Ltd
Current assignee: Sumitomo Chemical Co Ltd
Priority date: 1973-11-13
Filing date: 1974-11-12
Publication date: 1979-06-26
Also published as: NL7414759A; GB1477329A; JPS5077454A; FR2250803B1; FR2250803A1; DE2453638C3; DE2453638A1; NL180761B; DE2453638B2; JPS516714B2; IT1023234B; NL180761C

Abstract

ABSTRACT OF THE DISCLOSURE
A thermoplastic resin composition having excellent resistance to weather and impact comprises a binary graft-copolymer of a rubber component com-prising an ethylene-copolymer rubber and an aromatic vinyl compound or a ternary graft-copolymer of a rubber component comprising an ethylene-propylene rubber, an aromatic vinyl compound and a vinyl cyanide compound;
0.5 to 10% by weight of mineral oil having a specific gravity of 0.905 or more; and an antioxidant and/or an ultraviolet absorber.

Description

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1 Thls lnvention relates -to a thermopl.a~tic .
resin compos:iti.on cxcellent in weather reslstance and impact resist ~nce. More particularly, this invention relates to a composition comprising a binary gra.ft-copolymer of an ethylene-propylene rubber and an aromatic vinyl compound or a ternary graft-copolymer of these two components and a vinyl cyanide compound, a mi.neral oil, and an antioxidant and/or an ul-tra-: violet absorber. :
. 10 A development has heretofore been made of - .
.~ the process for producirg a graft-copolymer excellent ; in impact resistance as well as in weather resistance -.
` by graft-copolymerizing styrene or styrene and acrylo- .
.~ nitrile on an ethylene-propylene rubber, considering 15 that the ethylene-propylene rubber is excellent in .
weather resistance.
i : For preparing such impact resistant resins, there have been known a bulk polymerization method - ~:
~ ~ (U.S. Patent 3,538,192), an emulsion polymerization .~:
.~ ~ 20 method (U.S. Patent 3,435,096), and, in addition, a solution polymerization method (U.S. Patent 3,538,190 .~ and 3,538,191).
.~ Although the graft-copolymers obtained by .
~ such methods have a weather resistance comparable to ;~
.. : 25 - or even higher than that of, for example, ABS resins, ``, because &n ethy].ene-propylene rubber is used as the ~;~ rubber component, the graft-copolyrners have a defect ~ ;
that they are inferior in irnpact resistance particularly ~: at low temperatures to ABS resins. Further, when an ethylene-propylene rubber i.s used, it has been necessary :' ' , , , . ~

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1 that the ~mount of the rubber be 10 - 15% larger than that of thc diene rubber in ABS resins in order -to obtain the same impact resis-tance at room temperature `~
as that of the ABS resins.
It is a known fact that various stabilizers . ,. , , ~
have been added in order to prevent polymer materials ~ -from degradation. However, even if various antioxldants and ul-traviolet absorbers have been added for the purpose of increasing the weather resistance, the effect o:. such agents has only been recognizable in an early stage of exposure to light, and it has been considered to be difficult to sustain the effect for ~ ;~
a long period of time.
~` Further, as an example of addition of mineral ~`
: . . .
oil to rubber-reinforced plastic such as ABS resins ~ ~ there have been known Japanese Patent Publications `~ No. Sho. 41-1551 (1966) and No. Sho. 41-16306 (]966).
However, the objects of these inventions are in replac-ing a part of expensive rubber by inexpensive mineral oil (Japanese Patent Publlcation No~ Sho. 41-1551) or in improving impact strength at low temperature, ;~
~ hardness and processability by addition of mineral `` oil (Japanese Patent Publication No. Sho. 41-16306).
As a result of examination iDy the inventors of the ;~
25 present invention, however, there has been kno~l that, ~ ~r in said rubbe:.-reinforced plastics such as ABS resin containing diene type Yubber, a mere addition of mineral oil thereto does not make an improvement on the weather resistance and also on the impact strength at low -temperature.
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~ 7445 An object of this invention is to provide a thermoplastic resin composition having excellent impact resistance particularly at low temper-ature and weather resistance.
Another object of the invention is to provide a thermoplastic resin composition comprising a graft-copolymer of an aromatic vinyl compound and/or a vinyl cyanide compound on an ethylene-propylene rubber; mineral oil;
and an antioxidant and/or an ultraviolet absorber.
Other objects and advantages of this invention will be apparent from the following description. -;
The inventors of this invention have done extensive research ~o find that the impact resistance particularly at low temperature may be im-proved and the weather resistance may become excellent by adding mineral oil and an antioxidant and/or an ultraviolet absorber to a binary graft-copolymer .. ..
of an ethylene-propylene rubber and an aromatic vinyl compound or a ternary graft-copolymer of these two components and a vinyl cyanide compound. `
According to this invention, there is provided a thermoplastic resin composition having excellent resistance to weather and impact, which :. l ., ~ .
:l comprises~
~ ~A~ a graft-copolymer which is--- 20 ta) a binary graft-copolymer of ~1) a rubber component com- -:
prising at least 40% by weight of an ethylene-propylene 1 rubber selected from the group consisting of an e~hyl-:. ene-propylene copolymer and ethylene-propylene terpoly-mers and ~2) an aromatic vinyl compound, or ~b) a ternary graft-copolymer of ~1) a rubber component com-prising at least 40% by weight of an ethylene-propylene , rubber selected from the group consising of an ethylene-propylene copolymer and ethylene-propylene terpolymers~
~2) an aromatic vinyl compound and ~3) a vinyl cyanide . 30 compound;
~ ~5 c~ o~ h.~/o~
~L~ ~B) 0.5 to 10% by weight of mineral oi~1having a specific gravity of 0.905 or more; and ::
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(C) an antioxidant, an ultraviolet absorber or both.
.~ The above thermoplastic resin composition can be prepared by ` adding to the binary or ternary graft-copolymer obtained by a conventional method 0.5 - 10% by weight of mineral oil and an antioxidant and/or an ultraviolet absorber. In producing the graft- ~ , the additives in this invention may be added either before or after the polymerization, ` or during the course of polym0rization.
Contrary to the conventional way of securing approximately ` the same impact resistance as that of an ABS resin by increasing the .~ ethylene-propylene rubber content of the graft-copolymer, this invention '; lO enables a resin having impact resistance comparable to that of the ABS
resin to be obtained by simply adding 0.5 to 10%, preferably l to 5%, by weight of mineral oil to the binary or ternary graft-copolymer. The ` effect of addition of an antioxidant and/or an ultraviolet absorber to -~
the graft-copolymer in this invention is amazingly enhanced in the pre-sence of mineral oil. So far as the weather resistance is concerned, the graft-copolymer in this invention is generally superior to the `i~
, ABS resin~ but the effect of addition of an antioxidant and/or an ultraviolet absorber has been recognizable only in an early stage of exposure to light, whereas the addition of mineral oil enables the effect of said additives on the light exposure to be sustained for a long period of time.
The mineral oil for use in this inv~ntion is ., :

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7~'~5 a colourless or pàle yellow naphthene type hydrocarbon oil having a specific gravity of 0.905 or more. ~-The antioxidants for use in this invention are of phenolic type, thioether type, amine type, phosphite type, and dithio acid -salt type. The ultraviolet absorbers for use are of salicylic acid type, benzophenone type, and benzotriazole type. These : :
~ stabilizers may be used usually either alone or in combination of , . , two or more and added usually in a proportion of 0.05 to 3% by -weight based on the weight of the resin composition.
It is not desirable to add more than 10% by weight of mineral oil to the graft-copolymer, because the mechanical properties are markedly decreased and the balance of physical properties is damaged.
On th0 other hand, an addition of less than 0.5% by weight thereof does not give a desirable effect.
The ethylene-propylene rubbers for use in this invention ~` include not only a binary copolymer consisting of ethylene and propylene (hereinafter referred to as EPM)~ but also ethylene-, propylene terpolymers (hereinafter referred to as EPDM) consisting of said two components and a third component such as, for example, ., ~
' 20 dicyclopentadiene, ethylidenenorbornene, . .~ . ~ .

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he~adiene, 1,5-hexadlene, 2-methyl-1,5-hexadiene, l,~-cycloheptadiene, 1,5-cyclooct~diene, and mixtures of these compounds.
The ethylene-propylene rubbers for use are preferably those in which the molar ratio of ethylene to propylene is in the range frorn 5 : 1 to l : 3.

. . . .
The propor-tion of unsaturated radicals in EPDM corres-. . .
ponds preferably to an iodine number of 4 to 50. It ~-is also possible to use at least two rubbers. As the ~
10 rubber component, there may be employed blends of 40 ~ ;
to 99.9% by weight of EPDM or ~PM with 60 to 0.1% by weight of one or more members selected from,for example.
polybutadiene, polyisoprene, and styrenebutadiene rubbers.
Such blends of different types of rubbers are suitably selected according to the intended use.
~ xamples of the aromatic vinyl compounds to be used include, for example, one or more members ;~ ~ selected from styrene, a-methylstyrene, ~-chloro-- styrene, dimethylstyrene and the like. Of these, styrenè is preferred. ~ Acrylonitrile, methacrylo-nitrile and the like may be used as the vinyl cyanide .:~ : ,~
; compound.
The weight ratio of these vinyl compounds ~ to the rubber may be selected from a suitable range, A~ 25 depending upon the intended use. Usually, 5 to 20 by weight of the rubber component is used with 95 to . 80~o by weight of the aromatic vinyl compound for the ;~
binary graft-copolymer or the aromatic vinyl and vinyl cyanide compounds for the ternary graft-copolymer.

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~ 74~5 1 However, in case a graft-copolymer is to be prepared for the purpose of improving its compatibil:Lty with other rubbers or resins, a weight ratio of the rubber componen-t to the vinyl compounds as high as possible is preferable because the degree of grafting is i.n-creased. For i.nstance, a pre~erable range is from : ~ 20 to 90~0 by weight of the rubber component based on ~ :~
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:~ the weight of the vinyl compounds. :~ ~
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: . In the case of a ternary graft-copolymer 10 of the ethylene-propylene rubber with an aromatic . , .. vinyl compound and a vinyl cyanide compound, the . weight ratio between both monomers is adjusted with-. in the range from 4 : 3 to 5 : 1. For example, in .. i . -the copolymerization system of styrene and acrylo-, , . 15 ni-trile, the most suitable weight ratio ranges from .
65 : 35 to 80 : 20. ... `~
he graft-copolymer for use in this inven- :~:
tion can be prepared by bulk polymerlzation, emulsion .
; polymerization, and solution polymerization. Since the ethylene-propylene rubber is i.nsoluble by nature in a monomer mixture of styrene and acrylonitrile in :.
the above-mentioned ratio, and al.so a stable emulsi.on of an ethylenc-propylene rubber cannot easily be reproduced, the graft-copolymer obtained by bulk ~-. 25 polymerization or emulsion polymerization tends to . be inferior in impact resistance to that obtained by ;~
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.. : solution polymerization. Although a graft-copolymer ~ :

: obta:ined by any polymerization method can be markedly improved in impact strength particular]y at low tempe-0 ratures, by the addition of mineral oi.l, the most .'; ' ' ; :' 10~i7g~5 .
~ 1 pronounced effect of the la.tter is exhibited in the . . , ; case of a gra:r-t-copolymer ob-tained by a solution poly-. . merization method.
In preparing a gra.ft-copolyrner for use in:~
5 this invcntion by the solutlon polymerizat:ion method, .
. sui-table solvents are pentane, n-hexane, 3-methylpentane, ::: 2-methylpentane, 2,2- and 2,4-dimethylpentanes, heptane, .
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::~ cyclopentane, cyclohexane, and alkyl-substituted ;
cyclopentane and cyclohexane in which the alkyl has : lO :l to ~ carbon atoms; also usable are aromatic hydro~ .~
` carbon solvents such as benzene, toluene, dimethyl- : :
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.~ benzenes, xylenes, ethylbenzene, diethylbenzenes, and : triethylbenzenes.
On the other hand, solvents which may also ~ :
be used in combination wlth the above-listed aliphatic or aromatic hydrocarbon solvents are ketones such as ` ~ acetone, methyl ethyl ketone, methyl-n-propyl ketone, -.; diethyl ketone, 2~hexanone, 3-hexanonej acetophenone~
:: and propiophenone; esters such as:methyl formate, ~:~ 20 ethyl formate, methyl acetate, ethyl acetate, n~propyl : -: i .
-:.z acetate, n~butyl acetate, n~amyl acetate, methyl .~
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~ propionatej and methyl n~butyrate; ethers such as :~
.~ tetrahydrofurane and dioxane; halogen~substituted ~, .
aliphatic hydrocarbons such as dichloroethane and - ~
25 chloroform; and hydrocarbons containing hetero atoms ~ ~;
selected from nitrogen, oxygen and sulfur, such as . ~ pyridine, aniline, acetonitrile, dimethylformamide, dimethyl sulfoxide and the like.
~ The catalysts to be used in the grafting :. 30 reaction are conventional radical polymerization '' :

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; ~ g _ ::' ,' . ~ ' . . , : , ~ .: . . . , : , 79~45 1 catalysts. Suitable catalysts are, for example, peroxldes such as benæoyl peroxide, lauroyl peroxide, di-tert-butyl perioxide, acetyl peroxide, tert-butyl peroxybenzoic acid, dicwnyl peroxide, peroxybenzoic acid, peroxyacetic acid, tert-butyl peroxypivalate and the like; and diazo compounds such as azobisisobutyro-nitrile, and the like.

i , The catalyst may be used in an amount of ~`
O.1 to 10% by weight based on the weight of tha 10 vinyl monomer. The suitable polymerization tempera- ~
ture is 30C to 120~, particularly 50C to 80C. ~;
The polymerization time depends markedly on polymeri-zation conditions, and is preferably adjusted so that the conversion may reach 90~ or higher in 5 to 40 hours.
In this invention, the incorporation of an -antioxidant, ultraviolet absorber, and mineral oil can be effected by adding these additives to the polymerization reaction mixture while being s-tirred before, during, or after polymeriY~ation, or by blend-`i; ing them with the isolated graft-copolymer immediately :. :
before the latter is granulated in a granulator.

The invention is illustrated below in detail with reference to Examples, but the invention is not limited thereto.
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- Example ~
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Into a 10-liter separable flask provided with a Dimroth cooler, a thermometer, a glass tube for bubblir~g a gas, a Hopkins cooler, and a stirrer :::, , . i-..
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1~57445 .
Wit}l three turbine-type blades were charged 324 g of EPDM having an iodine number of 8.5, a Mooney viscosity of 61, and a propylene content of ~3% by weight, and containing ethylidenenorbornene as the diene component, 3,600 g of n-hexane, and 1,800 g of styrene. To the charged mixture, after having been thoroughly dissolved, were added 600 g of acrylonitrile and 48 g of benzoyl peroxide diluted with 2,400 g of ethylene chloride, and the resulting mixture was allowed to polymerize at G7C. for 10 hours while being agitated at 600 rpm under an argon atmosphere. After completion of the reaction, the graft-polymerization solution was subjected to precipitation in 25 liters of methanol. The precipitate was separated and dried under reduced pressure at 50C. for 20 hours, and then at 150C. for 3 hours to obtain a graft-copolymer having a rubber content of 13.7% by weight.
To 100 parts by weight of ~he copolymer thus obtained were added 3 parts by weight of mineral oil, namely Sonic Process Oil [a registered trademark of Nippon Kogyo (Japan Mining) Co., Ltd., and manufactured by '"~; the same], naphthene type R-1000, or aromatic types X-100, X-140 or X-200, 0.5 part by weight of a thioether-type antioxidant ~Sumilizer TPS, a ` registered trademark of Sumitomo Chemical Co. for distearyl thiodipropionate), ; 0.5 part by weight of a phenolic antioxidant (Irganox 1010, a registered trademark of Ciba Geigy Co. for tetrakis (methylene 3-(3',5'-di-t-butyl-4'- ~ -hydroxyphenyl)propionate)methane), and 0.5 part by weight of a benzophenone-type ultraviolet absorber (Sumisorb 10, a registered trademark of : .
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1 Sumitomo Chemical Co. :~or 2-hydroxy-4-me~thoxybenzophe-none). The mixture was pelletized by means of an extruder and a pelletizer and molded by means of' an in,jection molding machine to prepare JIS No. 3 dwnbbell test pieces for tes-t:ing the tensile strength and test pieces for testi.ng Izod impac-t strength specif'ied in . ASTM D 256-56. Using these test pieces, the tensile strength was tested at room temperature at a testing :
speed of 5 mm per minute, and the Izod impact strength ; 10 was tested in conformity with ASTM D 256-56. ~::

Referential Example ~ ~
' To a test of tensile strength and impact ' , ':strength was subjected the resin composition obtained in the same manner as in Example, except that the `,15 mineral oil was not added to the graft-copolymer obtain~
ed in Example.
he test results obtained in Example and .
~`-Referential Example were as shown in Table 1.

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I'able \ \ Physical. _ _ Notched Izod \ property strength impact strength \ ~ 2 (kg-cm/cm2) \ Min.eral \ (kg/cm ) ._~ . .
Examplè oil \ 20a oa -30a __ s p . r ~ _ : R - 1000 0. 9300 512 29.2 15.3 9.5 .~ . Example X - 100 1. 0037 532 21.2 14.6 9 - 3 x - 140 1.0065 53~ lg . o 15.0 9 - 5 ~; X - 20G 1. 0154 52~ 23.0 14.2 ~ .1 ~ ~ ~
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REXf ple 543 ¦ 17. 2 10.9 4.9 . .

-~, I The resin compositions obtained in Example : ~ and Referential Example were compression-molded to . prepare sheets, 3 mm in thickness. These sheets were exposed to light for 100, 200, and 400 hours in Sunshine 5 Weather-0-meter wE-suN-Ha, manufactured by Toyo Rika Co. Test pieces were cut from the exposed sheets and ~ tested for change in impact strength by means of a :
-~ Dynstat impact tester in conformity with BS 1330-1946 :
and DIN 53,453. The test results were as shown in ` 10 Table 2.
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. R - 1000 bneak bneak 43.3 32.1 Dynstat strength Example X - 100 nbeak bneak 41.4 30.4 : ;
(kg-cm/cm2) X - 140 bnreak bneak 42-3 31-4 ~ ¦ L l X - 200~ brea `.`.~ Example _ break 51 4 21. a 16.4 :'' ` ~ ' ~ . ,, ~: , ': :, ' ' `, :: ' : .

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A thermoplastic resin composition having excellent resistance to weather and impact, which comprises:
(A) a graft-copolymer which is:
(a) a binary graft-copolymer of (1) a rubber component com-prising at least 40% by weight of an ethylene-propylene rubber selected from the group consisting of an ethylene-propylene copolymer and ethylene-propylene terpolymers and (2) an aromatic vinyl compound, or (b) a ternary graft-copolymer of (1) a rubber component com-prising at least 40% by weight of an ethylene-propylene rubber selected from the group consisting of an ethylene-propylene copolymer and ethylene-propylene terpolymers, (2) an aromatic vinyl compound and (3) a vinyl cyanide compound;
(B) 0.5 to 10% by weight of colourless or pale yellow naphthene type mineral oil having a specific gravity of 0.905 or more; and (C) an antioxidant, an ultraviolet absorber or both.

2. A thermoplastic resin composition according to Claim 1, wherein the amount of the mineral oil is 1 to 5% by weight.

3. A thermoplastic resin composition according to Claim 2, wherein both an antioxidant and an ultraviolet absorber are present.

4. A thermoplastic resin composition according to Claim 1, 2 or 3 wherein the ethylene-propylene rubber is selected from the group consisting of an ethylene-propylene copolymer, an ethylene-propylene-dicyclopentadiene ter-polymer, an ethylene-propylene-ethylidene-norbornene terpolymer, an ethylene-propylene-1,4-hexadiene terpolymer, an ethylene-propylene-1,5-hexadiene ter-polymer, an ethylene-propylene-2-methyl-1,5-hexadiene terpolymer, an ethylene-propylene-1,4-cycloheptadiene terpolymer and an ethylene-propylene-1,5-cyclo-octadiene terpolymer.

5. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the ethylene-propylene rubber has a molar ratio of ethylene to propyl-ene of 5 : 1 to 1 : 3.

6. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the terpolymer has an iodine number of 4 to 50.

7. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the rubber component consists of 40 to 99.9% by weight of the ethyl-ene-propylene rubber and 60 to 0.1% by weight of at least one member selected from the group consisting of polybutadiene, polyisoprene and styrene-butadiene rubber.

8. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the aromatic vinyl compound is selected from the group consisting of styrene, .alpha.-methylstyrene, .alpha.-chlorostyrene, and dimethylstyrene.

9. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the vinyl cyanide compound is selected from the group consisting of acrylonitrile and methacrylonitrile.

10. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the weight ratio of the ethylene-propylene rubber to the vinyl com-pound is 5 - 20% by weight to 95 - 80% by weight.

11. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the ternary graft-copolymer contains the aromatic vinyl compound and the vinyl cyanide compound in a weight ratio of 4 : 3 to 5 : 1.

12. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the ternary graft-copolymer consists of the ethylene-propylene rubber, styrene and acrylonitrile, the weight ratio of the styrene to the acrylonitrile being 65 : 35 to 80 : 20.

13. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the antioxidant is a phenolic type, thioether type, amine type, phos-phite type or dithio acid salt type.

14. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the ultraviolet absorber is a salicyclic acid type, benzophenone type or benzotriazole type.

15. A thermoplastic resin composition according to Claim l, 2 or 3, wherein the rubber component consists of an ethylene-propylene-ethylidenenor-bornene terpolymer, the aromatic vinyl compound is styrene and the vinyl cyanide compound is acrylonitrile.

16. A thermoplastic resin composition according to Claim 1, 2 or 3, wherein the graft-copolymer is prepared by the solution polymerization method.

17. A thermoplastic resin composition according to Claim l, 2 or 3, wherein the graft-copolymer is prepared by the solution polymerization method and the solvent used is pentane, n-hexane, 3-methylpentane, 2-methylpentane, 2,2- and 2,4-dimethylpentane, heptane, cyclopentane, cyclohexane, or an alkyl-substituted cyclopentane or cyclohexane in which the alkyl has l to 4 carbon atoms.

18. A thermoplastic resin composition according to Claim l, 2 or 3, wherein the graft-copolymer is prepared by the solution polymerization method and the catalyst used in the grafting reaction is benzoyl peroxide, lauroyl peroxide, di-tert-butyl peroxide, acetyl peroxide, tert-butyl peroxybenzoic acid, dicumyl peroxide, peroxybenzoic acid, peroxyacetic acid, tert-butyl peroxypivalate or azobisisobutyronitrile.

l9. A thermoplastic resin composition according to Claim l, 2 or 3, wherein the graft-copolymer is prepared by the solution polymerization method and the polymerization is carried out in the presence of 0.1 to 10% by weight of the catalyst based on the weight of the vinyl monomer at a termperature of 50°C to 80°C and so that the conversion reaches 90% or higher in 5 to 40 hours.