GB2085452A

GB2085452A - Olefin copolymer resin compositions

Info

Publication number: GB2085452A
Application number: GB8126496A
Authority: GB
Original assignee: Idemitsu Petrochemical Co Ltd
Current assignee: Idemitsu Petrochemical Co Ltd
Priority date: 1980-09-03
Filing date: 1981-09-01
Publication date: 1982-04-28
Also published as: JPS5747344A; BE890172A; DE3133574A1; FR2489349B1; FR2489349A1

Abstract

A polypropylene-based resin composition having excellent impact resistance and weld characteristics comprises from 50% to 90% by weight of a crystalline ethylene-propylene block copolymer and from 50% to 3% by weight of an ethylene- propylene-diene elastic terpolymer having a Mooney viscosity (ML1+4, 100 DEG C) of from 70 to 150.

Description

SPECIFICATION Resin compositions The present invention relates to resin compositions and provides a range of polypropylene-based resin compositions which have particularly good impact resistance and weld characteristics.

One of the disadvantages of homopolymers of propylene is that their impact resistance is poor.

In order to improve such poor impact resistance of polypropylene, it is well known to mix polypropylene with low density polyethylene, amorphous ethylene-propylene copolymer, or amorphous ethylene-propylene-diene terpolymer. The resulting compositions, however, suffer from the disadvantage that weld characteristics which are significant factors in injection moulding are seriously deteriorated although the impact resistance is improved.

It has therefore been the subject of a long and continuous search to improve the poor impact resistance of polypropylene without the deterioration of weld characteristics. For this purpose, several methods have been proposed, including the method of Japanese Patent Publication No.

39987/1976 in which a specific propylene-ethylene block copolymer is used as a base resin and a small amount of low density polyethylene is added thereto. There is, however, still a need further to improve the weld characteristics.

The invention provides a polypropylene-based resin composition comprising from 50% to 97% by weight of a crystalline ethylene-propylene block copolymer and from 50% to 3% by weight of an ethylene-propylene-diene elastic terpolymer having a Mooney viscosity of 70 to 1 50 (ML, +4, 100"C). It has unexpectedly and surprisingly been found that the compositions of the invention have particularly good weld characteristics as well as good impact resistance.The specific range of Mooney Viscosities given for the elastic terpolymer is quite specific and characteristic, although a preferred range of Mooney viscosities (ML, +4, 100"C) is from 80 to 1 20. All the Mooney viscosities as described hereinafter are determined under the same conditions as above, i.e., My1+4, 100"C.

The crystalline ethylene-propylene block copolymer used in the composition of the invention preferably has a melt index (MI) of from 0.2 to 10 grams/l0 minutes, advantageously from 0.5 to 8 grams/l0 minutes, and an ethylene content of from 3% to 30% by weight.

The elastic terpolymer preferably has a propylene content of from 20% to 60% by weight, and a diene content of from 1 % to 15% by weight. Examples of suitable dienes include hexadiene, dicyclopentadiene, ethylidenenorbornene, methylenenorbornene, propylenenorbornene and isoprene.

The polypropylene-based resin composition of the invention comprises from 50% to 97% by weight, preferably from 60% to 95% by weight, of the crystalline ethylene-propylene block copolymer and from 50% to 3% by weight, preferably from 40% to 5% by weight, of the ethylene-propylene-diene elastic terpolymer.

The polypropylene-based resin composition of the invention can contain usual auxiliary additives, such as anti-oxidants, heat stabilizers, ultraviolet absorbing agents, and colourants. In addition, suitable amounts (usually 0 to 50% by weight of the composition) of fillers such as calcium carbonate, kaolin, talc, asbestos and glass fibres can be added.

In preparing the polypropylene-based resin composition according to the invention, the crystalline ethylene-propylene block copolymer and ethylene-propylene-diene elastic terpolymer, and if necessary, auxiliary additives may be fillers are mixed, fully kneaded at a temperature of from 1 70 to 230"C by the use of an extruder, a co-kneader or a Banbury mixer. The composition is then generally pelletized. The resulting pellets can be injection-moulded at a temperature of from 200"C to 300"C, resulting in moulded articles with good weld characteristics and impact resistance. The moulding composition is suitable for the manufacture of components for motor cars and electrical appliances.

The resin compositions of the invention are also suitable for blow moulding.

The invention is illustrated in the following Example.

EXAMPLE In accordance with the formulations shown in Table 1, ingredients were compounded and kneaded in a Banbury mixer, and the resultant mixture was moulded to a sheet. The sheet was pulverized or pelletized by the use of a sheet pelletizer, and the resulting pellets were injectionmoulded to provide a test piece. A further such invention-moulded product was cut to provide a specimen for the Izod impact test. With these test pieces, the physical tests were performed.

The results are shown in Table 2.

The tensile strength, tensile elongation and Izod impact strength as general physical properties were measured by the usual testing methods (according to the methods defined in JIS K 7113 and K 7110).

With regard to the weld characteristics, the tensile elongation test was performed using a test piece (Type: dumbbell No. 2, thickness 2 millimetres) according to JIS K 7113, and the tensile impact strength test was performed using a test piece (Type L) according to ASTM D 1 822.

The symbols used in Table 1 are as follows: PP Propylene homopolymer (MI = 3.5, density (D) = 0.91 grams/cubic centimetres) BPP-1 Ethylene-propylene block copolymer (MI = 2.3, D = 0.91, ethylene content = 10% by weight) BPP-2 Ethylene-propylene block copolymer (Ml = 2.8, D = 0.91, ethylene content = 9.7% by weight) EPR-1 Ethylene-propylene elastic copolymer (Mooney viscosity = 40, propylene content = 49% by weight) EPR-2 Ethylene-propylene elastic copolymer (Mooney viscosity = 70, propylene content = 26% by weight) EPDM- 1 Ethylene-propylene-ethylidenenorbornene elastic terpolymer (Mooney viscosity = 65, propylene content = 43% by weight, ethylidenenorbornene content = 5% by weight) EPDM-2 Ethyiene-propyiene-ethylideneorbornene elastic terpolymer (Mooney viscosity = 88, propylene content = 28% by weight, ethylidenenorbornene content = 5% by weight) EPDM-3 Ethylene-propylene-hexadiene elastic terpolymer (Mooney viscosity = 97, propylene content = 27% by weight, hexadiene content = 3% by weight) Table 1 Ingredients compounded (parts by weight) Compositin No. PP BPP-1 BPP-2 EPR-1 EPR-2 EPDM-1 EPDM-2 EPDM-3 1 - 100 - - - - 15 2 - 100 - - - - - 15 3 - - 100 - - - - 15 4 - - 100 - - - - 30 5* - - 100 - - - - 6* 100 - - - - - - 15 7* - - 100 - - 15 - 8* - - 100 15 - - - 9* - - 100 - 15 - - *Comparative examples Table 2 General Physical Properties Weld Characteristics Tensile Tensile Impact Strength Tensile Tensile Impact Composition Strength Elongation (kg.cm/cm) Elongation Strength No.

(Kg/cm) (%) 23 C -30 C (%) (kg.cm/cm 1 320 700 80 11 670 122 2 310 700 81 10 660 176 3 310 700 82 10 96 123 4 340 700 85 30 126 178 5* 280 600 14 5 72 110 6* - - - - 8 36 7* 310 700 81 10 17 136 8* 310 700 82 11 21 115 9* 310 700 81 10 23 123 *Comparative examples It can beseen from the results shown in Table 2 that the polypropylene-based resin compositions Nos. 1 to 4 of the present invention have substantially better impact resistance and weld characteristics than the comparative polypropylene-based resin compositions Nos. 5 to 9 which are outside the scope of the invention.

Claims

1. A polypropylene-based resin composition comprising from 50% to 97% by weight of a crystalline ethylene-propylene block copolymer and from 50% to 3% by weight of an ethylenepropylene-diene elastic terpolymer having a Mooney viscosity (ML, +4, 100"C) of from 70 to 150.

2. A resin composition according to claim 1, wherein the ethylene-propylene-diene elastic terpolymer has Mooney viscosity (ML, + 1 OO"C) of from 80 to 120.

3. A resin composition according to claim 1 or claim 2, comprising from 60% to 95% by weight of the crystalline ethylene-propylene block copolymer and from 40% to 5% by weight of the ethylene-propylene-diene elastic terpolymer.

4. A resin composition according to any preceding claim, wherein the crystalline ethylenepropylene block copolymer has a melt index (MI) of from 0.2 to 10 grams per 10 minutes, and an ethylene content of from 3% to 30% by weight.

5. A resin composition according to claim 4, wherein the crystalline ethylene-propyiene block copolymer has a melt index (MI) of from 0.5 to 8 grams per 10 minutes.

6. A resin composition according to any preceding claim, wherein the ethylene-propylenediene elastic terpolymer has a propylene content of from 20% to 60% by weight.

7. A resin composition according to claim 6, wherein the terpolymer has a diene content of from 1% to 15% by weight.

8. A resin composition according to any preceding claim, wherein the diene component of the ethylene-propylene-diene elastic terpolymer is hexadiene, dicyclopentadiene, ethylidenenorbornene, methylenenorbornene, propylenenorbornene or isoprene.

9. A polypropylene-based resin composition according to claim 1, substantially as disclosed in the Example herein.