CA1266735A

CA1266735A - Impact-resistant resin composition

Info

Publication number: CA1266735A
Application number: CA000525465A
Authority: CA
Inventors: Maki Ishizawa; Hiroaki Koga; Tsuneo Kuwabara; Akio Kiyohara; Yasumi Tanaka; Hiroshi Ohshima
Original assignee: Tosoh Corp
Current assignee: Tosoh Corp
Priority date: 1985-12-17
Filing date: 1986-12-16
Publication date: 1990-03-13

Abstract

Abstract of the Disclosure:
An impact-resistant resin composition comprising:
(A) 100 parts by weight of an ethylene - vinyl acetate -vinyl chloride graft copolymer obtained by graft-polymerizing vinyl chloride to an ethylene - vinyl acetate copolymer;
(B) 1 to 20 parts by weight of a polyester type modifier having an average molecular weight of 500 to 8,000; and (C) 1 to 30 parts by weight of at least one selected from the group consisting of the following polymers (a) to (e):
(a) olefin polymers, (b) styrene type polymers, (c) acrylic type or modified acrylic type polymers, (d) chlorine type polymers, and (e) an ethylene - vinyl acetate - carbon monoxide copolymer.
The composition has a low melt viscosity and accord-ingly has good moldability and productivity as well as impact resistance and appropriate bending characteristics.
Hence, it is useful as a sheathing material for outdoor cables or as a material for pipes for electric wires, hoses for various fluids, etc.

Description

IMPACT-RESISTANT RESIN COMPOSITION
Backqround of the Invention:
l. Field of the Invention The present invention relates to an impact-resistant resin composition excellent in moldability, productivity and various other characteristics. More particularly, the present invention relates to an impact-resistant resin composition having impact resistance, weather resistance, flame retardancy and long-ter~ heat resistance ~thermal aging resistance) and usable in the field of sheathing material for various cables capable of resisting high speed impacts by bullets shot from firearms, etc. as well as in the fields of flexible pipes for enclosing electric wires and pipes and hoses for various fluids which require an appropriate bending characteristic.

2. Description of the Prior Art Polyethylene type compositions or soft polyvinyl chloride type compositions have conventionally been used as sheathing materials for various types of cable, as pipes for encasing electric wires such as flexible pipes and protective pipes, or as materials for pipes and hoses for various fluids.
Products used in such applications are often bent or wound when used in practice. Therefore, the resin composi-tions constituting these products are required to have an appropriate bending characteristic (modulus of elasticity in flexure).
When the above-mentioned compositions are used as sheathing materials for various cables, the compositions are also required to have not only impact resistance but . -- 1 --~Z ~ ~7 ~ 5 also an appropriate modulus of elasticity in flexure capable of absorbing the energy of a high speed impact such as one caused by a bullet shot from a firearm. In these applica-tions, the compositions are generally required to have addi-tional properties such as resistance to low temperatures (resistance to becoming brittle at low temperatures), weather resistance (ultraviolet degradation resistance), long-term heat resistance (thermal aging resistance), flame retardancy and chemical resistance.
The polyethylene type compositions have had drawbacks in terms of impact resistance, low temperature resistance, weather resistance, flame retardancy, etc.
In order to ameliorate these drawbacks oP the poly-ethylene type compositions, it has been the general practice to increase the thickness of molded articles or to add to a polyethylene type resin various additives such as an impact resistance improver, an ultraviolet absorber and a flame retardant. None of these methods, offered sufficient impro-vements, however, because the polyethylene type resin itself is poor in impact resistance, weather resistance and flame retardancy. In order to obtain a sufficient degree of impro-vement effect, said additives (impact resistance improver, ultraviolet absorber, flame retardant, etc.) needed to be added in large amounts, which of course proved disadvantageous in economic terms.
As regards soft polyvinyl chloride type compositions, these are generally of the type that is plasticized with a high molecular or low molecular modifier. In these plasticized compositions, several tens of parts by weight (approximately) of said modifier is used per 100 parts by weight of a polyvinyl chloride type resin; as a res~lt, the compositions inevitable become soft and are not able to possess a modulus of elasticity in flexure high enough to absorb the energy of high speed impact and, moreover, are low in impact resistance. When a low molec~lar modifier is used, the resulting molded articles change in characteristics when used over a long term due to the vaporization or migration of the modifier; it is therefore difficult for such molded articles to retain their weather resistance and heat resist-ance at desired levels over a long period of time.
One type of product which has been able to solve both of the drawbacks of the polyethylene type compositions and the soft polyvinyl chloride type compositions plasticized with a modifier is an ethylene - vinyl acetate - vinyl chloride graft copolymer.
This type of graft copolymer is excellent in impact resistance, weather resistance and flame retardancy, can be given appropriate bending characteristics by controlling the proportions of the ethylene - vinyl acetate copolymer and vinyl chloride, and can demonstrate a sufficient resistance to high speed impacts caused by bullets shot from firearms, etc., together with excellent impact resistance.
However, such an ethylene - vinyl acetate - vinyl chloride graft copolymer generally has a high melt viscosity as compared with the polyethylene type compositions and the soft polyvinyl chloride type compositions plasticized with a 7~35 modifier, and therefore displays great resistance to kneading (a large motor load) when subjected to extrusion molding or injection molding. Therefore, good moldability and produc-tivity as seen in the polyethylene type compositions has not been obtainable with this type of graft copolymer.
Ethylene - vinyl acetate - vinyl chloride graft copolymers have also sufered another drawback in that the increase of kneading temperature (for example, up to about 200~C3 needed to reduce its melt viscosity causes the thermal degradation of the resin and causes an article molded there from to have poor surface characteristics.
In order to reduce the melt viscosity of the above graft copolymer without increasing its kneading temperature, it has been proposed that it would be effective to add to the copolymer a modifier o~ phthalic acid ester type, aromatic carboxylic acid ester type, aliphatic dibasic acid ester type, epoxy type, phosphoric acid ester type, fatty acid ester type, chlorine-containing type, or polyester type, all of which are generally known as modifiers of polyvinyl chloride.
However, a desired melt viscosity cannot be obtained by the addition of such a modifier in a small amount (for example, several parts by ~eight or less), and the addition of a large amount (for example, 10 parts by weight or more) of such a modifier is necessary in order to obtain a prefer-able melt viscosity. The addition of such a large amount of modifier results in an excessive softening of the resulting molded material and renders the latter's resistance to bullet impact, etc. insufficient.

~ 5 Further, apart from the polyester type modifier, the above modifiers display another drawback in that they cause vaporization and migration to occurs with respect to other resins when the molded article containing them is used over a long period of time.
While, the polyester type modifier, having a large molecular weight and good compatibility with the ethylene -vinyl acetate - vinyl chloride copolymer, causes no vaporiza tion or migration with respect to other resins and accord-ingly causes little problem of reliability when a moldedarticle containing this modifier is used over a long period of time, when such a modifier is singly added to said copoly~
mer, it needs to be added in a large amount (for e~ample, 10 parts by weight or more) in order to obtain a sufficiently reduced melt viscosity. This reduces the impact resistance of the mol~ed~*rticle.
Summary of the Invention:
It is therefore an object of the present invention to provide a resin composition which comprises, as a main com-ponent, an ethylene - vinyl acetate - vinyl chloride graft copolymer and which is given improved moldability and produc-tivity without impairing the impact resistance, weather resistance and appropriate bending characteristics inherently possessed by said main component.
Other objects and advantages of the present invention will become apparent to those skilled in the art from the following description and disclosure.

7~3:5 Detailed Description of the Preferred Embodiment:
The present invention relates to an impact-resistant resin composition comprising:
(A) 100 parts by weight of an ethylene - vinyl acetate -vinyl chloride graft copolymer obtained by graft-polymeri~ing vinyl chloride to an ethylene - vinyl acetate copolymer;
(B) 1 to 20 parts by weight of a polyester type modifier having an average molecular weight of 500 to 8,000; and (C) 1 to 3~ parts by weight of at least one selected from the group consisting of the following polymers ~a) to (e):
(a) olefin polymers selected from the group consisting of a polyethylene, a polypropylene and an ethylene - propylene copolymer, (b) styrene type polymers selected from the group consist-ing of a polystyrene and a styrene - butadiene copolymer, (c) acrylic type or modified acrylic type polymers selected from the group consisting of an acrylonitrile - butadiene copolymer, an acrylonitrile - butadiene - styrene copolymer, a methacrylic acid ester - butadiene - styrene copolymer and an acrylic acid - acrylic rubber type copolymer, (d) chlorine type polymers selected from the group consist-ing of a chloroprene, a chlorinated polyethylene and a shlorosulfonated polyethylene, and (e) an ethylene - vinyl acetate - carbon monoxide copolymer.
The impact-resistant resin composition of the present invention, as compared with those of the prior art, has a reduced melt viscosity and accordingly has significantly improved moldability and productivity without impairing the impact resistance and appropriate bending characteristics.
The present invention will be explained in detail below.
In the ethylene - vinyl acetate - vinyl chloride graft copolymer (A) used in the present invention, the proportion of the ethylene - vinyl acetate copolymer component is 5 to 50%
by weight. When the proportion is less than 5% by weight, the resulting composition of the present invention is poor in impact resistance. When the proportion exceeds 50% by weight, the composition is soft and lacks appropriate bending charac-teristics. The ethylene - vinyl acetate copolymer component preferably contains 5 to 50% by weigh of vinyl acetate and preferably has a melt index of 0.8 to 50 g/10 min. When the vinyl acetate content in the ethylene - vinyl acetate copoly-mer component is less than 5% by weight, the reaulting compo-sition of the present invention is poor in impact resistance.
When the vinyl acetate content exceeds 50% by weight, the composition is soft and not only has insufficient bending characteristics but also shows reduced impact resistance.
When the ethylene - vinyl acetate copolymer component has a melt index smaller than 0.8, the resulting composition has deteriorated moldability and productivity; and when the melt ; index is larger than 50, the composition is too soft.
; 25 The polyester type modifier (B) used in the present invention is represented by the following general formula:

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or ~ O - ~ - O - C - R2 - I t-n O R3 11 4 O O O , O
and is prepared by a polycondensation reaction between alcohols and acids. Said alcohols include a monohydric alcohol tRl-OH) such as methanol, ethanol, octanol, lauryl alcohol, stearyl alcohol, benzyl alcohol, etc. and a dihydric alcohol (~1O-R3-OH) such as ethylene glycol, propylene glycol, butylene glycol~ 1,6-hexanediol, etc.; and said acids include a monobasic acid (R4-COOH) such as ace~ic acid, propionic acid, octylic acid, lauric acid, stearic acid, benæoic acid, etc. and a dibasic acid (HOOC-R2-COOH) such as malonic acid, succinic acid, adipic acid, sebacic acid, maleic acid, phthalic acid, azelaic acid, etc.
The polyester type modifier (B) is selected so as to have a molecular weight of 500 to 8,000. (Accordingly, the n in the above general formula takes such a value that this molecular weight will be assured.) When the molecular weight of the polyester type modi~ier (B) is smaller than 500, the modifier may cause vaporization and migration in the result-ing composition of the present invention. When the molecular weight exceeds 8,000, the composition has strikinyly reduced levels of processability and cold resistance leading to problems during use. In order to obtain a composition causing no vaporization and migration and having good processability ~.Z~ r-and cold resistance, the polyester type modifier most prefer-ably has a molecular weight of 1,500 to 3,000.
In the present invention, as well as the ethylene -vinyl acetate - vinyl chloride graft copolymer (A) and the polyester type modifier (B), at least one polymer ~C) is used which is selected from the group consisting of olefin polymers (a), polystyrene type polymers (b), acrylic type polymers (c), chlorine-containing polymers (d) and ethylene - vinyl acetate - carbon monoxide copolymers (e). Of the olefin pol~mers (a), the ethylene - propylene copolymer has component proportions by weight of 7 to 3 (ethylene) and 3 to 7 (propylene). Of the polystyrene type polymers (b), the styrene - butadiene copolymer has component proportions by weight of 2 to 5 (styrene) and 8 to 5 (butadiene). Of the acrylic type polymers tc), the acrylonitrile - butadiene copolymer has component proportions by weight of 2 to 5 (acrylonitrile) and 8 to 5 (butadiene): the acrylonitrile -butadiene - styrene copolymer has component proportions by weight of 2 to 4 (acrylonitrile), 1 to 3 (butadiene) and 4 to 7 (styrene); the methacrylic acid ester - butadiene -styrene copolymer has component proportions by weight of 2 to 4 (methyl or ethyl methacrylate), 3 to 6 (butadiene) and 4 to 5 (styrene); and the acrylic acid - acrylic rubber type copol~mer has component proportions by weight of 8 to 3 (acrylic acid) and 2 to 7 (acrylic rubber). Of the chlorine-containing polymers (d), the chlorinated polyethylene is chlo~inated by 10 to 70% by weight. Preferably, the ethylene - vinyl acetate - carbon monoxide copolymer (e) contains 20 _ 9 _ ~Z66 ~ 35 to 40% by weight of vinyl acetate and 5 to 20% by weight of carbon monoxide and has a melt index of 30 to 40 g/10 min.
In the present invention, the proportions of the three components, namely, the ethylene vinyl acetate ~ vinyl chloride graft copolymer (A), the polyester type modifier (B) and at least one polymer (C) selected from the above-mentioned polymers are important.
In the present invention, 1 to 20 parts by weight of the component (B) and 1 to 30 parts by weight of the compo-nent (C) are used per 100 parts by weight of the component(A). When the component (~) is ~sed in an amount less than 1 part by weight, the melt viscosity of the component (~), namely, the ethylene - vinyl acetate - vinyl chloride graft copolymer (A), cannot be reduced to a desired level and the resulting composition of the present invention is unable to possess improved moldability and productivity. When the amount of the component (B) exceeds 20 parts by weight, the composition is soft and acc~rdingly lacks appropriate bending characteristics, is poor in impact resistance and suffers from severe brittleness at low temperatues. When the compo-nent (C) is used in an amount less than 1 part by weight, the resulting composition of the present invention shows insuffi-cient improvement in terms of impact resistance, brittleness at low temperature, etc. When the amount of component (C) exceeds 30 parts by weight, further improvements in said properties are not obtainable and such excessive addition is uneconomical. When the component (C) is an ethylene - vinyl acetate - carbon monoxide copolymer, the addition amount is ~Z~735 preferably in the range o~ 1 to 15 parts by weight for the same reasons as mentioned above.
The resin composition of the present invention can further comprise, as necessary, additives ordinarily used in resins, such as a stabilizer~ a lubricant, a flame retardant, an ultraviolet absorber, an antioxidant, an antistatic agent and a desired coloring agent.
The resin composition of the present invention can be produced by uniformly mixing an ethylene - vinyl acetate -vinyl chloride graft copolymer (A), a polyester type modifier(B), at least one polymer (C) selected from the above-mentioned polymers and, as necessary, various additives ~e.g.
a stabilizer, a lubricant) in a ~]enschel mixer, a Banbury mixer or the like, in accordance with a known method. The lS composition thus produced can be subjected to any of the conventional molding methods such as extrusion molding, injection molding and the like.
; The molded articles made of the composition of the present invention has a low melt viscosity and accordingly has good moldability and productivity as well as impact resistance and appropriate bending characteristics.
Hence, it is useful as a sheathing material for out-door cables or as a material for pipes for electric wires, hoses for various fluids, etc.
ExamPles The present invention will be explained more specifi-cally bellow by way of Examples. However, the present inven-tion is in no way res~ricted to these Examples.

ExamPles 1 to 5 One hundred parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer [Ryuron Graft H-130 (brand name):Ryuron NPF S-4 (brand name) = 1:2J manufactured by Toyo Soda Manufacturing Co., Ltd. was mixed with 13 parts by weight of a polyester (polyadipic acid ester) type modifier (PN-446) manufactured by Adeka Argus Kagaku K.K. and 5 parts by weight of an acrylonitrile - butadiene copolymer [Chemigum P-83 (brand name)] manufactured by Good Year Tire & Rubber Company. 5imilar mixtures were prepared using the following compounds in place of the acrylonitrile - butadiene copolymer:
a methacrylic acid ester - butadiene - styrene copolymer [Methablen C-102 (brand name)l manufactured by Mitsubishi Rayon Co., Ltd., an acrylic acid - acrylic rubber type co-lS polymer [Kaneace FM (brand name)] manufactured by Kanegafuchi Chemical Industry Co., Ltd., a chlorinated polyethylene [Daisorack G-235 (brand name)l manufactured by Osaka Soda Co., Ltd. and a chlorosulfonated polyethylene ETOSO CSM
TS-530 (brand name)] manufactured by Toyo Soda Manufacturing Co., Ltd. To each of the mixtures were added a stabilizer and carbon black. Each of the resulting mixtures was kneaded for 10 minutes using a hot roll of 165C and then pressed for 5 minutes using a hot press of 180C to prepare a sheet.
Various test samples were prepared from these sheets. Using these test samples, various tests were conducted as mentioned below. Separately, 65 g of each of the above resin composi-tionC was placed in a roller type mixer (internal volume: 60 cc) attached to a plasticorder manufactured by Brabender Co.

;735 and kneaded at 150C (mixer temperature) and 60 rpm (rotor revolution) to measure a steady torque in kneading.
Table 1, shows the results of measurement of Charpy impact strength, modulus of elasticity in flexure, fracture energy in a high speed punching test (punching speed: 7 m/sec), fracture energy in a shotgun test and steady torque when kneaded by Brabender plasticorder. Incidentally, the frac-ture energy measurement in the shotgun test was obtained by measuring the speed at which a bullet must travel for it to pass through a test sample followed by a calculation based on that speed. The fracture energy measurement in the high speed punching test was calculated on the basis of a curve representing the elongation produced by the stress measured at the time of punching.

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Comparative Examples 1 to 8 One hundred parts by weigh of an ethylene - vinyl acetate vinyl chloride copolymer (same as in Examples 1 to 5) was mixed with parts by weight of a polyester type modifier (same as in Examples 1 to 5); similar mixtures were prepared using the following ~ompounds in place of the poly-ester type modifier in the amounts indicated in Table 2, an acrylonitrile - butadiene copolymer (same as in Example 1), a methacrylic acid ester - butadiene - styrene copolymer (same as in Example 2), an acrylic acid - acrylic rubber type copolymer (same as in Example 3), a chlorinated polyethylene (same as in Example 4) and a chlorosulfonated polyethylene (same as in Example 5). To each of these mixtures were added a stabilizer and carbon black. Then, test sample preparation and testing were conducted in the same manner as in Examples 1 to 5. The results are shown in Table 2.
Comparative ExamPles 9 to 11 One hundred parts by weight of a vinyl chloride homo-polymer [Ryuron 700E (brand name)] manufactured by Toyo Soda Manufacturing Co., Ltd. was mixed with 40 parts by weight of a polyester type modifier (same as in Examples 1 to 5); two further batches of a similar mixture ~ere prepared except that dioctyl phthalate replaced the polyester type modifier in the amounts mentioned in Table 2. Then, test sample preparation and testing were conducted in the same manner as in Examples 1 to 5. The results are shown in Table 2.

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i6735 As will be appreciated from the results of Comparative Example l, when only an ethylene - vinyl acetate - vinyl chloride copolymer is used, both the fracture energy in the high speed punching test and the fracture energy in the shotgun test were comparatively high owing to the synergistic effect of good Charpy impact strength and good modulus of elasticity in flexure; however, the torque in kneading is large and the moldab_lity and productivity are both poor.
As will be seen from Comparative Example 3, when lO0 parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer is ~ixed with only 20 parts by weight or more of a polyester type modifier, the resulting composition has a reduced torque in kneading but is too soft Eor measurement of Charpy impact strength at 23C to be conducted and displays low fracture energies. Comparative Examples 4 to 8 show that when lO0 parts by weight of an ethylene - vinyl acetate -vinyl chloride copolymer is mixed with only 30 parts by weight of any one of the group consisting of an acrylonitrile - butadiene copolymer, a methacrylic acid ester - butadiene -styrene copolymer, an acrylic acid - acrylic rubber type copolymer, a chlorinated polyethylene and a chlorosulfonated polyethylene, the resulting composition has comparatively high fracture energies but its torque in kneading is not reduced at all.
As Comparative Examples 9 to ll show, when a vinyl chloride homopolymer is mixed with a polyester type modifier or dioctyl phthalate, the resulting soft polyvinyl chloride composition is very soft and has low fracture energies.

In contrast, as is obvious from Examples 1 to 5, when an ethylene - vlnyl acetate - vinyl chloride copolymer is mixed with a polyester modifier and any one of the group consisting of an acrylonitrile - butadiene copolymer, a methacrylic acid ester - butadiene - styrene copolymer, an acrylic acid - acrylic rubber type copolymer, a chlorinated polyethylene and a chlorosulfonated polyethylene, the result-ing composition has the capability to maintain the high impact resistance and appropriate modulus of elasticity in flexure inherently possessed by the ethylene - vinyl acetate - vinyl chloride copolymer and, as a result, displays a high fracture energy in high speed punching and shotgun tests.
Further, the composition has a small torque in kneading by Brabender and thus exhibits excellent moldability and productivity.
ExamPle 6 One hundred parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer lRyuron Graft H-130 (brand name):Ryuron NPF S-4 (brand name) = 1:2] manufactured by Toyo ~0 Soda Manufacturing Co., Ltd., were mixed with 17 parts by weight of a polyester (polyadipic acid ester) type modifier ~PN-446) manufactured by Adeka Argus Kagaku K.K., 6 parts by weight of an ethylene - vinyl acetate - carbon monoxide copolymer [Elvalloy 742 (brand name)] manufactured by Mitsui-Dupont Chemical K.K., a stabilizer and carbon black. Themixture was kneaded using a roll of 165C and various test samples were prepared therefrom. Using these test samples, the tests which are mentioned below were conducted.

-- lg --In Table 3 are shown the measurement results of Charpy impact strength, modulus of elasticity in flexure, fracture energy in a high speed punching test tpunching speed: 7 m/sec), fracture energy in a shotgun test and steady torq~e in knead-ing by Brabender. Incidentally, the fracture energy measure-ment in the shotgun test was obtained by measuring the speed at which a bullet must travel for it to pass through a sample followed by making a calculation based on that speed. The fracture energy measurement in the high speed punching test was calculated using a stress-elongation curve as in Examples 1 to 5.

One hundred parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer (same as in Example 6), were mixed with 13 parts by weight of a polyester tpolyadipic acid ester) type modifier (same as in Example 6), 5 parts by weight of an ethylene - vinyl acetate - carbon monoxide copolymer (same as in Example 6), a stabilizer and carbon black. Then, test sample preparation and testing were conducted in the same manner as in Example 6. The results are shown in Table 3.
Example 8 One hundred parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer (same as in Example 6), were mixed with 2 parts by weight of a polyester (polyadipic acid ester) type modifier (same as in Example 6), 3 parts by weight of an ethylene - vinyl acetate - carbon monoxide copolymer (same as in Example 6), a stabilizer and carbon ~66~3S

black. Then, test sample preparation and testing were conducted in the same manner as in Example 6. The results are shown in Table 3.
Example 9 One hundred parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer ~same as in Example 6), were mixed with 7 parts by weight o a polyester (polyadipic acid ester) type modifier (same as in Example 6), 4 parts by weight of an ethylene - vinyl acetate - carbon monoxide copolymer (same as in Example 6), a stabilizer and carbon black. Then, test sample preparation and testing were conducted in the same manner as in Example 6. The results are shown in Table 3.

ExamPle 1 0 One hundred parts by weight of an ethylene - vinyl acetate vinyl chloride copolymer (same as in Example 6), were mixed with 17 parts by weight of a polyester (polyadipic acid ester) type modifier ~PN-230) manufactured by Adeka Argus Kagaku K.K., 5 parts by weight of an ethylene - vinyl acetate - carbon monoxide copolymer (same as in Example 6), a stabi-lizer and carbon black. Then, test sample preparation and testing were conducted in the same manner as in Example 6.
The results are shown in Table 3.
Comparative ExamPle 12 One hundred parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer (same as in Example 6), were mixed with 15 parts by weight of an ethylene - vinyl acetate - carbon monoxide copolymer (same as in Example 6), a 73:~

stabilizer and carbon black. Then, test sample preparation and testing were conducted in the same manner as in Example 6.
The results are shown in Table 3.
As will be appreciated from the results of Comparative Example 12, when 100 parts by weight of an ethylene - vinyl acetate - vinyl chloride copolymer is mixed with only 15 parts by weight of an ethylene - vinyl acetate - carbon monoxide copolymer, the resulting composition shows low fracture energy in high speed punching and shotg~n tests and its torque in kneading is not reduced.
Incidentally, Charpy impact strength and modulus of elasticity in flexure were measured according to ~IS K 7111 and JIS K 7203, respectively.

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Claims

The embodiments of the invention in which an exclusive property or privilege are claimed are defined as follows:

1. An impact-resistant resin composition comprising:
(A) 100 parts by weight of an ethylene - vinyl acetate -vinyl chloride graft copolymer obtained by graft-polymerizing vinyl chloride to an ethylene - vinyl acetate copolymer;
(B) 1 to 20 parts by weight of a polyester type modifier having an average molecular weight of 500 to 8,000; and (C) 1 to 30 parts by weight of at least one selected from the group consisting of the following polymers (a) to (e):
(a) olefin polymers selected from the group consisting of a polyethylene, a polypropylene and an ethylene propylene copolymer, (b) styrene type polymers selected from the group consist-ing of a polystyrene and a styrene - butadiene copolymer, (c) acrylic type or modified acrylic type polymers selected from the group consisting of an acrylonitrile - butadiene copolymer, an acrylonitrile - butadiene - styrene copolymer, a methacrylic acid ester - butadiene - styrene copolymer and an acrylic acid - acrylic rubber type copolymer, (d) chlorine type polymers selected from the group consist-ing of a chloroprene, a chlorinated polyethylene and a chlorosulfonated polyethylene, and (e) an ethylene - vinyl acetate - carbon monoxide copolymer.

2. The impact-resistant resin composition according to Claim 1, wherein the polymer (c) is at least one polymer selected from the group consisting of an acrylonitrile -butadiene copolymer, a methacrylic acid ester - butadiene -styrene copolymer, an acrylic acid - acrylic rubber type copolymer, a chlorinated polyethylene, a chlorosulfonated polyethylene and an ethylene - vinyl acetate - carbon monoxide copolymer.

3. The impact-resistant resin composition according to Claim 1, wherein the proportion of the ethylene - vinyl acetate component in the ethylene - vinyl acetate - vinyl chloride graft copolymer (A) is 5 to 50% by weight, and said ethylene - vinyl acetate copolymer component contains 5 to 50% by weight of vinyl acetate and has a melt index of 0.8 to 50 g/10 min.

4. The impact-resistant resin composition according to Claim 1, wherein the polyester type modifier (B) has a molecular weight of 1,500 to 3,000.