JPS61252248A - Rubber composition - Google Patents

Abstract

PURPOSE:To provide a rubber compsn. which has a low specific gravity and excellent rubber elasticity, is suitable for use as automotive parts and can be vulcanized, by blending an alpha-olefin/1,4-diene copolymer resin having a specified composition with natural or synthetic rubber. CONSTITUTION:1-100pts.wt. unsaturated copolymer resin obtd. by copoly merizing to least one 2-12C alpha-olefin (e.g. ethylene or propylene) and at least one 1,4-diene of the formula (wherein R' is 8C or lower alkyl; R<2>, R<3> are each H, 8C or lower alkyl) (e.g. 4-methyl-1,4-hexadiene or 5-methyl-1,4-hexadiene) in the presence of a Ziegler-Natta catalyst for the polymn. of alpha-olefin, is mixed with 100pts.wt. rubber selected from among natural and synthetic rubbers (e.g. styrene/butadiene rubber, isoprene rubber) to obtain the desired rubber compsn.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention provides a product which has low specific gravity and high physical properties, especially excellent rubber elasticity, and which is produced by copolymerization with specific 1,4-dienes and α-olefins. The present invention relates to a vulcanizable rubber composition containing an unsaturated copolymer resin obtained by.

(Prior art) It has been common practice to add large amounts of inorganic fillers such as silica, calcium carbonate, Merck, and clay to improve the physical properties of rubber compositions or reduce costs. It is being done.

However, these various inorganic fillers have a specific gravity of 2.0 to 2.0.
8, the specific gravity of various rubbers as the base material is 0.8
5 to 1.00, but it is significantly larger than that, and has the disadvantage of increasing the specific gravity of the rubber composition.

In order to improve this drawback, various crystalline polyolefins and non-grade polyolefins such as atactic polypropylene, which are relatively inexpensive and have a low specific gravity, have been used as substitutes for inorganic fillers.

(Problems to be Solved by the Invention) However, rubber compositions to which these polyolefins are added have various physical properties, particularly rubber elasticity, which are inferior to rubber compositions to which various inorganic fillers are added. are doing.

The reason for this is thought to be that non-grade polyolefins such as various crystalline polyone fins and atactic polypropylene have almost no functional groups in their molecular chains and therefore do not participate in vulcanization.

On the other hand, in recent years, in fields such as automobile parts applications, manufacturing processes have been made to have lower specific gravity (lighter weight) in order to save energy and resources.
, there was an even stronger demand for higher physical properties (higher performance).

(Means for Solving the Problems) The present invention aims to obtain a rubber composition that has low specific gravity and high physical properties, particularly excellent rubber elasticity, by blending a specific unsaturated copolymer resin into rubber. It can be vulcanized by
This was done with the idea of achieving this purpose.

That is, the present invention provides ``100 parts by weight of at least one rubber selected from the group of natural rubber and synthetic rubber, and 2 carbon atoms.
-Unsaturated copolymer resin 1- obtained by copolymerizing at least one selected from the α-olefins of step 2 and at least one 1°4-diene represented by the following formula (I)
A rubber composition comprising 100 parts by weight.

(Here, R1 is an alkyl group having 8 or less carbon atoms, t and R
Each represents 3 hydrogen atoms or an alkyl group having 8 or less carbon atoms. However, R2 and R3 are never both hydrogen atoms. )”.

(Function) The rubber used in the present invention is natural rubber or synthetic rubber, and specific examples of the latter include styrene-butasher rubber, butadiene rubber, nitrile-butadiene rubber, ethylene-propylene rubber, and ethylene-propylene-diene rubber. , inprene rubber, inbutylene-isoprene rubber, silicone rubber, etc., preferably butadiene rubber, ethylene-propylene rubber, ethylene-propylene rubber, etc.
Examples include propylene-diene rubber, imprene rubber, inbutylene-isoprene rubber, especially ethylene-propylene rubber, ethylene-propylene-diene rubber, and butadiene rubber.

The specific gravity of the synthetic rubber is generally from 0.85 to 1.3 degrees, and from the viewpoint of dispersibility, it is preferably 1 or less, particularly 0.95 or less.

Furthermore, the unsaturated copolymer resin used in the present invention has 2 carbon atoms.
-12 α-olefins and the formula (I
) is a copolymer resin with at least one specific 1,4-diene. ``Resin'' ethylene, propylene, butene-1,4-methylpentene-1
The term refers to everything from crystalline homopolymers such as those that are soft and have a certain degree of elasticity, and excludes so-called "rubber-like materials" (such as natural rubber-like materials). That is, to give a tentative guideline for the "resin" state mentioned here, the initial elastic modulus at room temperature is i o oH17ai ~ i o o, o
o.

Yen/-1 preferably 300 Ayf/cd ~ 80,0
00 to 9j/d, more preferably 700#f/cli
~s o, o o o isj/-.

Examples of α-olefins having 2 to 12 carbon atoms, which are constituents of this resin, include ethylene, propylene, butene-1, pentene-1, hexene-1, octene-1,3
-Methylbutene-1,3-methylpentene-1,4-methylpentene-1,3,3-dimethylbutene-1,4,
4-dimethylpentene-1,3-methylhexene-1,
4-Methylhexene-1,4,4-dimethylhexene-
1,5-methylhexene-1, allylcyclopentane,
Allylcyclohexane, styrene, allylbenzene, 3
-cyclohexylbutene-1, vinylcyclopropane,
Examples include vinylcyclopentane, vinylcyclohexane, and 2-vinylbicyclo(2,2,1)-hebutane. Among these, preferred examples include ethylene, propylene, butene-1, pentene-1, hexene-1,3-methylbutene-1,3-methylpentene-1
, 4-methylpentene-1,3-methylhexene-1,
Examples include styrene, and ethylene, propylene, butene-1,3-methylbutene-1, and 4-methylpentene-1 are particularly preferred.

One type of these α-olefins may be used, or two or more types may be used as long as the resin does not become anything other than the above-mentioned resinous material. When two or more types of α-olefins are used, the α-olefins may be randomly distributed in the resin or may be distributed in blocks.

The above formula (f) is another structural feature of this resin.
Examples of the 1,4-dienes represented by are 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4-ethyl-1,4-hexynadiene, 4,5
-dimethyl-1,4-hexadiene, 4-methyl-1,
4-heptadiene, 4-ethyl-1,4-hebutadiene, 5-methyl-1,4-hebutadiene, 4-ethyl-1
, 4-octadiene, 5-methyl-1,4-octadiene, 4-n-propyl-1,4-decadiene, and the like.

Among these, particularly preferred 1,4-dienes are 4-
Methyl-1,4-hexadiene, 5-methyl-1,4-
It is hexadiene. These 1,4-dienes may be used alone or in combination of two or more, and preferred examples include 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene.
Combined use of methyl-1,4-hexadiene (95:5-5:
95).

This resin is produced by converting the above α-olefin and 1,4-dienes into α-olefins using a Ziegler-Rokutsuta catalyst for α-olefin polymerization, particularly a catalyst for producing crystalline polymers of α-olefins.
- It can be produced by copolymerization using the same method and equipment as in the production of olefin polymerization.

Examples of such manufacturing methods include, for example,
73808, 106494, 106495, 11
Examples include 2597 and 131231.

As for the number of monomers contained in this resin and the distribution of each type of monomer, there are no particular limitations as long as the resin does not become anything other than a resin-like substance, as stated in the definition above. Examples of preferred types from the viewpoint of the molecular structure of the resin are as follows.

(I1 Random copolymer of one or more α-olefins and one or more 1,4-dienes.

(2) Block copolymerization consisting of one or more α-olefin polymer blocks and a random copolymer block of one or more α-olefins and one or more 1,4-dienes Coalescing (the type and quantitative ratio of the α-olefin in the α-olefin polymerization block may be the same or different from those of the α-olefin in the random copolymerization main block).

(3) A random copolymer block (block a) of one or more α-olefins and one or more 1,4-dienes, and an α-olefin and 1,4-dienes.
A random copolymerization block (block b) with dienes, in which 8 of the α-olefins contained in this block b
Type 1, number, and quantitative ratio, as well as types of 1,4-dienes,
A block copolymer consisting of a block in which at least one of the number and quantitative ratio is different from block a.

Specific preferred examples of this resin include ethylene and 4
-Random copolymer of methyl-1,4-hexadiene, random copolymer of ethylene and 5-methyl-1,4-hexadiene, ethylene and 4-methyl-1,4-hexadiene and 5-methyl Random copolymer of -1,4-hexadiene, propylene and 4-methyl-1,4-
Hequinadientonorandum copolymer, propylene and 5-
Random copolymer with methyl-1゜4-hexadiene,
Random At combination of propylene and 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene, propylene and ethylene and 4-methyl-1,4-hexadiene and 5-methyl-1, Random copolymer with 4-hexadiene, butene-1 and 4-methyl-1,4-
Random copolymer with hexadiene, butene-1 and 4-
Methyl-1,4-hexadiene and 5-methyl-1,
Random copolymer with 4-hexadiene, 3-methylbutene-1 and 4-methyl-1,4-hexadiene and 5
-Random copolymer with methyl-1゜4-hexadiene, random copolymer with 4-methyl-pentene-1 and 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene , a block copolymer consisting of an ethylene homopolymer block and a random copolymer block of ethylene and 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene, a propylene homopolymer block and propylene and 4-methyl-1,4
- block copolymer consisting of hexadiene and a random copolymer block with 5-methyl-1,4-hexadiene, a homopolymer block of propylene and ethylene with 4-methyl-1,4-hexadiene and 5-methyl-1 , a block copolymer consisting of a random copolymer block with 4-hexadiene, a homopolymer block of ethylene, and a block copolymer of propylene with 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene. A block copolymer consisting of a random copolymer block, a random copolymer block of propylene and ethylene, and a random copolymer of propylene, ethylene, 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene a block copolymer consisting of a copolymer block, a homopolymer block of butene-1, butene-1, 4-methyl-1,4-hexadiene, and 5-methyl-1,
A block copolymer consisting of a random copolymerized block with 4-hexadiene, a homopolymerized block of 4-methylpentene-1, 4-methylpentene-1, 4-methyl-L4-hequinadiene, and 5-methyl-1 , a block copolymer consisting of a random copolymer block with 4-hexadiene, a random copolymer block of ethylene with 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene, and a block copolymer with propylene. Block copolymer consisting of 4-methyl-4-hexadiene and a random copolymer block with 5-methyl-1,4-hexadiene, propylene and 4-methyl-1,4-hexadiene and 5-methyl-1 , 4: Block copolymer consisting of a random copolymer block with hexadiene and a random copolymer block with propylene, ethylene, 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene , propylene and 4-methyl-1,4-hexadiene as well as 5-methyl-1,4-
Random copolymerized blocks with hexadiene, random copolymerized blocks with propylene, ethylene, 4-methyl-1,4-hexadiene and 5-methyl-1,4-hequinadiene, and ethylene and 4-methyl-1, A block copolymer consisting of 4-hexadiene and a random copolymer block with 5-methyl-1,4-hexadiene, ethylene and 4-methyl-1,4-hexadiene and 5-methyl-1,4- Random copolymer blocks with hexadiene and ethylene and propylene with 4-methyl-1,4-hexadiene and 5-methyl-1,4-
Examples include block copolymers consisting of random copolymerized blocks with hequinadiene. Here, the term "block copolymer" refers to the following copolymers. For example, "a block copolymer consisting of a homopolymer block of monomer A and a random copolymer block of monomer A and monomer B" means a block copolymer consisting of a homopolymer block of monomer A and a random copolymer block of monomer A and monomer B. The copolymer block is chemically bonded to form A-A-AA.
In addition to those that have the shape of It also means a mixture containing a homopolymer of monomer A, a random copolymer of monomer A and monomer B, etc.

Similarly, "a block copolymer consisting of polymer block a and polymer block b" refers to a block copolymer in which polymer block a and polymer block b are chemically bonded together. It also includes a copolymer in which polymer block a and polymer block b are chemically bonded, and also contains a mixture such as a polymer consisting only of polymer block a or a polymer consisting only of polymer block b. It has the same meaning as a so-called "block copolymer" synthesized using a Ziegler-Natsuta catalyst.

The amount of 1,4-dienes contained in this resin is 50 mol%
It is usually 0.1 to 30 mol%.

The molecular weight of this unsaturated copolymer resin is not limited as long as it can mix with the rubber component and be mixed uniformly, but usually the melt flow rate is o, o i y/10 minutes to 1.
o o o t/1o min (measurement conditions: J Engineering S K72
Preferably, the molecular weight corresponds to 10.230° C., 2.16# load).

The blending ratio of the above two components used in the present invention is 10 parts of the rubber component.
The amount of the unsaturated copolymer resin is 1 to 100 parts by weight, preferably 10 to 50 parts by weight, based on 0 parts by weight. If the amount of unsaturated copolymer resin is less than 1 part by weight, there is no improvement in physical properties (rubber elasticity) compared to when non-grade polyolefins such as various crystalline polyolefins or atactic polypropylene are used; on the other hand, if it exceeds 100 parts by weight Then it becomes too hard which is not desirable.

The composition of the present invention can be obtained by uniformly kneading the above two components. The kneading method may be a commonly used method such as a Banbury mixer or a roll, and the mixing method itself is not limited in any way.

In addition, in these steps, various compounding agents such as a plasticizer, a processing aid, a filler of 30% by weight or less, an anti-aging agent, and a pigment may also be mixed at the same time. For example, a method of kneading a compound consisting of rubber, the copolymer resin, and carbon black in one step, and a method of preparing a masterbatch in which a compound consisting of the copolymer resin and carbon black is kneaded in advance.
Various methods can be used, such as a method of additionally kneading rubber in the next step.

In the next step, the v4-conditioned composition is mixed with a vulcanizing agent, and in the next step, it is molded into a shape according to the intended use, and a rubber product is obtained through a flavoring step. The vulcanization method and vulcanization conditions may be appropriately determined depending on the intended use, shape, required performance, etc. of the rubber product.

The rubber composition of the present invention is useful in all fields where light weight, high rubber elasticity, and low cost are required, especially in the field of automobile parts.

(Example) The composition shown in Table 1 was kneaded in a Prabender Plastograph with a capacity of 100 cc at 180° C. and 70 rpm for 3 minutes, taken out, and then cooled to room temperature.

Next, this composition was mixed with a vulcanizing agent using a 6-inch roll at 60° C. to form a sheet. The obtained rubber composition was vulcanized by heating and pressurizing it with a press to create a sheet with a thickness of 2 m. The obtained sheet sample was evaluated in accordance with JIS K7112 for specific gravity and JIS K6301 for other physical properties. The results are shown in Table 1.

The above vulcanization conditions were the same as those in Examples 1 to 3 and Comparative Examples 1 to 3.
4 was heated and pressurized at 160°C for 30 minutes, and Examples 4 to 6 and Comparative Examples 5 to 8 were heated and pressed at 160°C for 20 minutes.

(Left below) @vl 1) Ethylene-propylene-ethylidene norbornene ternary copolymer rubber Mouni viscosity (ML1+4.100℃) 100 Propylene content 43 (i#) Ethylidene norbornene content t 15 (1% by weight) Specific gravity
0.86 2) Nato-2-methylthiuram monosulfide 3) 2-mercaptobenzothiazole 4) Crystalline polypropylene (homo) Melt flow rate (230°C) 1o (t/1$) 5
) Flopylene-methyl-1#4-to l? Diene random copolymer resin melt flow rate (230°C) 10 (f/10 min) l
Contains fk-1,4-hequinadiene 118 (mol ts) 6)
Measured at 70°C for 22 hours.

Claims (1)

[Claims] At least one selected from the group of natural rubber and synthetic rubber.
100 parts by weight of seed rubber, at least one selected from α-olefins having 2 to 12 carbon atoms, and the following formula (I)
1. A rubber composition comprising 1 to 100 parts by weight of an unsaturated copolymer resin obtained by copolymerizing at least one of the 1,4-dienes represented by: ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (Here, R^1 is an alkyl group with 8 or less carbon atoms, and R^2 and R^3 are hydrogen atoms or alkyl groups with 8 or less carbon atoms, respectively. However, both R^2 and R^3 are not hydrogen atoms.)