JP2596971B2 - Rubber composition - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a rubber composition having excellent weather resistance, heat resistance and ozone resistance. More particularly, the present invention relates to a chlorinated ethylene-propylene-based copolymer composition comprising (A) a chlorinated ethylene-propylene-based copolymer and (B) a rubber containing butanediene as a main component. It is an object of the present invention to obtain a rubber composition having not only good oil resistance and ozone resistance but also excellent oil resistance and good mechanical properties.

[Conventional technology]

For a long time, butanediene-based rubbers such as styrene-butanediene copolymer rubber (SBR) and acrylonitrile-butanediene copolymer rubber (NBR) have been used in various fields such as automobile parts, industrial rubber parts, and electric wire coating. ing. Butadiene-based rubber alone or blended with other rubbers such as cis-1,4-polyisoprene, polychloroprene, chlorosulfonated polyethylene, acrylic rubber, etc. The mechanical strength, electrical properties, compression set properties, etc. are easily improved.

[Problems to be solved by the invention]

In this blend (composition), the weather resistance, which is the most important item of rubber properties, is greatly reduced. Also, in the field of parts such as automobiles and home appliances, rubber containing butadiene as a main component is often used.
There is a strong demand for improvements in heat resistance, weather resistance, and the like, and there is a drawback that rubbers containing butadiene as a main component and blends as described above are not sufficiently satisfied.

As described above, the blends as described above are excellent in mechanical strength, compression set properties, weather resistance and physical properties such as flame retardancy, but are not satisfactory in other properties. Therefore, a composition having these properties balanced cannot be obtained.

From the above, the present invention is free from these drawbacks, that is, it provides a composition (mixture) having not only excellent mechanical strength but also excellent properties such as heat resistance, weather resistance and flame retardancy. An object of the present invention is to provide a composition which has the disadvantages of the generally used thermoplastic elastomers as described above.

[Means and actions for solving the problem]

According to the present invention, these problems are as follows: (A) the propylene content is 15 to 40% by weight, and the melt flow index is (according to JIS K7210;
Measured under conditions of 14, hereinafter referred to as “MFR”) 0.01 to 5.0 g / 10
Min., Melting peak measured by differential scanning calorimeter is 80 ° C.
The crystallinity measured by X-rays is 3% or more, and the weight average molecular weight (index of molecular weight distribution measured by gel permeation chromatography)
w) / ethylene having a number average molecular weight (n) of 4 or more
A chlorinated ethylene-propylene copolymer having a chlorine content of 20 to 45% by weight obtained by chlorinating a propylene copolymer and a Mooney clay (ML _{1 + 4} , 100 ° C) of 10 to 150. It is a composition comprising a polymer and (B) a rubber containing butanediene as a main component (hereinafter referred to as "butadiene rubber"), and a composition ratio of a chlorinated ethylene-propylene copolymer in the composition is 50 to 50%. 90% by weight
It can be solved by the following rubber composition. Hereinafter, the present invention will be described specifically.

(A) Chlorinated ethylene-propylene copolymer In producing the chlorinated ethylene-propylene copolymer used in the present invention, ethylene-
The propylene content of the propylene-based copolymer is 15 to 40% by weight, preferably 18 to 40% by weight, and particularly preferably 20 to 38% by weight. When chlorination is performed using an ethylene-propylene copolymer having a propylene content of 15% by weight, the resulting chlorinated ethylene-propylene copolymer has poor rubber-like elasticity, and is rather plastic-like in products. And does not exhibit the rubbery properties of the resulting composition. On the other hand, when chlorination is performed using an ethylene-propylene-based copolymer exceeding 40% by weight, the particles of the chlorinated ethylene-propylene-based copolymer obtained during chlorination increase, and the particles are aggregated in the reaction system. This is not preferred.

The ethylene-propylene copolymer has an MFR of 0.0
1 to 5.0 g / 10 min, preferably 0.02 to 5.0 g / 10 min, and particularly preferably 0.05 to 5.0 g / 10 min. If chlorination is performed using an ethylene-propylene copolymer having an MFR of less than 0.01 g / 10 minutes, the resulting chlorinated ethylene-propylene copolymer has poor processability. On the other hand, when chlorination is performed using an ethylene-propylene copolymer exceeding 5.0 g / 10 minutes, the reaction efficiency during the production of the chlorinated ethylene-propylene copolymer is poor, and the chlorinated product is strongly aggregated. .

The Mooney clay (ML _{1 + 4} , 100 ° C.) of the ethylene-propylene copolymer is usually 10 to 180, preferably 10 to 170, particularly preferably 10 to 150. If Mooney clay chlorinates less than 10 ethylene-propylene copolymers,
Agglomeration of chlorinated products during chlorination is severe. On the other hand, when an ethylene-propylene copolymer exceeding 180 is used, the mechanical properties of the obtained chlorinated product are excellent, but the rubber-like elasticity is poor and it is rather plastic-like.

The ethylene-propylene-based copolymer is usually a differential scanning calorimeter (Differential Scanning Calorimeter,
The melting peak measured by DSC) is 80 ° C or higher, and X
The degree of crystallinity measured by a line is 5% or more, preferably 80 to 125 ° C, particularly preferably 85 to 125 ° C. If the melting peak is lower than 80 ° C., the chlorinated ethylene-propylene copolymer becomes bulky when producing the chlorinated ethylene-propylene copolymer, which is not preferable because a uniform chlorinated product cannot be obtained.

The ethylene-propylene-based copolymer has a crystallinity of 3% or more as measured by X-ray, preferably 3 to 50%, and more preferably 3 to 45%. This crystallinity is 3
When chlorination is performed using less than 5% of an ethylene-propylene-based copolymer, the chlorination takes place at the chlorination stage, and a uniform chlorinated product cannot be obtained.

Further, the ethylene-propylene copolymer has a weight average molecular weight (w) / number average molecular weight (n), which is an index of molecular weight distribution measured by gel permeation chromatography (GPC), of 4 or more, and 4 to 8 Is preferred.
It is not preferable to use an ethylene-propylene copolymer having a w / n of less than 4 because the resulting chlorinated product has poor workability.

In order to produce the chlorinated ethylene-propylene copolymer of the present invention, the ethylene-propylene copolymer is suspended in an aqueous medium. In order to maintain this aqueous suspension, it is preferable to add a small amount of an emulsifier and a suspending agent. At this time, if necessary, a radical generator such as benzoyl peroxide, azobisisobutyronitrile and hydrogen peroxide, a defoaming agent such as light silicone oil, and other additives may be added.

In producing the chlorinated ethylene-propylene copolymer of the present invention, it is desirable to chlorinate the above aqueous suspension by the following three methods.

The first method uses the ethylene-
At least 25 ° C lower than the melting point of the propylene-based copolymer, but at a temperature higher than 50 ° C, the total chlorination amount
20 to 60% is chlorinated, and in the second stage, the temperature is 10 ° C. or more higher than the chlorination temperature in the first stage, but 5 to 15 ° C. higher than the melting point of the ethylene-propylene copolymer.
This is a method of performing the remaining chlorination at a low temperature.

In addition, the second method is at least 25% lower than the melting point of the ethylene-propylene-based copolymer used in the first step.
Although the temperature is lower than 20 ° C., at a temperature higher than 50 ° C., 20 to 60% of the total chlorinated amount is chlorinated, and in the second stage, the temperature is raised to a temperature 1 to 7 ° C. higher than the melting point of the ethylene-propylene copolymer. At a temperature of 2 to 25 ° C. lower than the melting point of the ethylene-propylene copolymer in the third step, in a third step. is there.

Further, the third method is at least lower than the melting point of the ethylene-propylene copolymer used in the first step.
Although the temperature is 25 ° C. lower, but chlorinates 20 to 60% of the total chlorination amount at a temperature higher than 50 ° C., the second stage is a temperature 10 ° C. or higher than the chlorination temperature in the first stage, At least 30% of the remaining amount of chlorination at a temperature 5 to 15 ° C. lower than the melting point of the ethylene-propylene copolymer, 60 to 90% of the total chlorination by this stage;
Then, in the third step, chlorination is performed at a temperature lower than the melting point of the ethylene-propylene copolymer but at least 2 ° C. lower than the melting point.

The chlorine content of the chlorinated ethylene-propylene copolymer used in the present invention thus obtained is 20.
-45% by weight (preferably 20-42% by weight, suitably 25%
~ 42% by weight). If the chlorine content of the chlorinated ethylene-propylene copolymer is less than 20% by weight, there is a problem in recovering and purifying the obtained chlorinated ethylene-propylene copolymer. Moreover, the flame resistance is poor. On the other hand, when the content exceeds 45% by weight, a chlorinated ethylene-propylene-based copolymer produced is not preferred because the thermal stability and heat resistance are significantly reduced.

Mooney viscosity is large at 100 ° C.
The rotor has 10 to 150 points, preferably 10 to 120 points, and more preferably 15 to 100 points.

Further, the melt flow index (measured under the condition of 8 in accordance with JIS K-7210, hereinafter referred to as "FR") is generally 1 to 100 g / 10 min, preferably 3 to 50 g / 10 min, particularly preferably 5 to 50 g / 10 min. ~ 30 g / 10 min is preferred.

(B) Butadiene rubber The butadiene rubber used in the present invention has a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of usually 5 to 200 in view of kneading properties and moldability and strength of the composition. Particularly preferred examples of the butadiene rubber are 10 to 180. Examples of the butadiene rubber include high cis-butadiene rubber, low cis-butadiene rubber, emulsion-polymerized styrene-butadiene copolymer rubber, solution-polymerized styrene-butadiene copolymer rubber, and acrylonitrile-butadiene. And copolymer rubber. Of these butadiene rubbers, the copolymerization ratio of butadiene in styrene-butadiene copolymer rubber and acrylonitrile-butadiene copolymer rubber is generally 40 to 85% by weight.
(Preferably 40 to 80% by weight).

(C) Composition Ratio The composition ratio of the chlorinated ethylene-propylene copolymer in the composition of the present invention is 50 to 90% by weight, particularly preferably 50 to 85% by weight. The composition ratio of the chlorinated ethylene-propylene copolymer in the composition is 50% by weight.
If it is less than 5, the resulting composition has poor weather resistance, heat resistance, and flame resistance. On the other hand, if it exceeds 90% by weight, good properties of the chlorinated ethylene-propylene copolymer cannot be reproduced.

(D) Mixing method, vulcanization method, molding method, etc. The composition (mixture) of the present invention can be obtained by uniformly blending the above substances, but furthermore, dehydrochlorination generally used in the rubber industry. Inhibitors, sulfur, sulfur donors, vulcanization accelerators, vulcanization accelerators, organic peroxides, crosslinking aids, plasticizers, oxygen, ozone, heat and light (ultraviolet) stabilizers, scotch inhibitors, Additives such as an anti-adhesive, a converting agent, a reinforcing agent, a foaming aid, a flame retardant, a flame retardant aid, a lubricant, and a colorant may be added according to the intended use of the composition.

When the composition of the present invention is manufactured, the compounding (mixing) method may be compounded using a mixer generally used in the art, such as an open roll, a drive render, a Banbury mixer, and a kneader. Among these mixing methods, in order to obtain a more uniform composition, two or more of these mixing methods may be applied (for example, after mixing by a drive render in advance, the mixture is mixed using an open roll). how to). If the mixing method is carried out at a relatively high temperature during melt-kneading, a part or all of the chlorinated ethylene-propylene copolymer used may be vulcanized or crosslinked. For this reason, it is usually necessary to carry out at 70 ° C. or lower.

The composition thus obtained is formed into a desired shape using an extrusion molding machine, an injection molding machine, a compression molding machine, a transfer molding machine or the like generally used in the general rubber industry.

In the case of vulcanization or cross-linking, the vulcanization or cross-linking is usually carried out during molding to a temperature range of 100 to 200 ° C., or by a steam can, an air bath or the like. The vulcanization or crosslinking time depends on the vulcanization or crosslinking temperature, but is generally between 0.5 and 120 minutes.

[Examples and Comparative Examples]

Hereinafter, the present invention will be described in more detail with reference to examples.

In the examples and comparative examples, JIS No. 3 dumbbells were manufactured in the tensile test according to JIS K6301.
Tensile strength (hereinafter “T _B ”) and elongation (hereinafter “E _B ”)
Was measured using a Shopper type tester according to JIS K6301. In addition, the heat resistance test was performed at a temperature of 120 ° C for 72 hours.
After leaving for a period of time, the residual ratio of tensile strength and the residual ratio of tensile elongation (elongation) were measured in accordance with JIS K6301. The weather resistance test was carried out using a sunshine weatherometer tester at a temperature of 40 ° C and an aging time of 250 hours (Agin
g), the residual ratio of tensile strength and residual ratio of tensile elongation were measured in the same manner. Furthermore, the ozone resistance test was conducted at a temperature of 40 ° C, an elongation of 20% and an ozone concentration of 50 pph according to JIS K6301.
m, was left for 200 hours under static conditions, and the presence or absence of cracks was observed. The flame retardancy was measured according to UL-94 method of safety standard of Underlight Laboratory (UL).

The chlorinated ethylene-propylene-based copolymer used in Examples and Comparative Examples, a rubbery material containing butadiene (hereinafter referred to as “butadiene-based rubber”), carbon black, a filler, an acid acceptor, and a crosslinking agent The types and physical properties of a vulcanizing agent, a crosslinking assistant, a vulcanization accelerator, a vulcanization accelerator, an antioxidant and a plasticizer are shown below.

[(A) Chlorinated ethylene-propylene copolymer]

As a chlorinated ethylene-propylene copolymer, an ethylene-propylene copolymer having a propylene content of 22% by weight in an aqueous suspension and having a Mooney viscosity (ML _{1 +} 4,100 ° C.) of 115 ( MFR 1.0g / 10min, melting point 120 ° C, below `` E
PR (1) ") 10kg, 50-90 with stirring
In the temperature range of ° C., the copolymer was chlorinated until the chlorine content of the copolymer reached 18.2% by weight (first stage chlorination). Next, the temperature of the reaction system was raised to 121 to 125 ° C., and introduction of chlorine was stopped in this temperature range, and annealing was performed for 30 minutes (second stage annealing). Then, cool the reaction system,
Chlorinated ethylene having a chlorinated content of 35.4% by weight in the temperature range of 95 to 118 ° C. (third stage chlorination) and having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 42.0. Propylene copolymer (MFR 10.0 g / 10 min.
IEPR (A) ") and 10 kg of the above EPR (1) were charged in the same manner as above, and chlorinated with stirring at a temperature in the range of 50 to 90 ° C. until the chlorine content of the copolymer reached 18.2% by weight. (First stage chlorination). Then, the reaction system is 105-115
℃, the chlorine content is 27.1 in this temperature range
Chlorination to 2% by weight (second stage chlorination). Then chlorinated in a temperature range of 118 to 120 ° C until the chlorine content becomes 30.2% by weight (third stage chlorination), Mooney viscosity (ML
_A chlorinated ethylene-propylene copolymer (FR 11.0 g / 10 min, hereinafter referred to as “CIEPR (B)”) having a ratio of 61 ( _{1 + 4} , 100 ° C.) was used.

[(B) butadiene rubber]

As a butadiene rubber, Mooney viscosity (ML
_{1 +} 4,100 ° C) is 52 and the copolymerization ratio of styrene is 2
Styrene-butadiene copolymer rubber (hereinafter referred to as “SBR”) having a 3.5% by weight, Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 44
And a butadiene homopolymer rubber (hereinafter referred to as "BR") having 97% cis-1,4 bonds, a Mooney viscosity (ML _{1 + 4} , 100 ° C) of 56, and a copolymerization ratio of acrylonitrile Was 35% by weight of acrylonitrile-butadiene copolymer rubber (hereinafter referred to as "NBR").

[(C) carbon black]

Further, as the carbon black, carbon black manufactured by the furnace method (manufactured by Showa Cabot Co., Ltd., trade name: Show Black FEF, average particle diameter 51 nm, specific surface area 41 m ² / g, FE
F, hereinafter referred to as "CB").

[(D) filler]

As a filler, calcium carbonate treated with a fatty acid (manufactured by Shiraishi Kogyo Co., Ltd., trade name Shirahika cc, specific gravity 2.56, average particle diameter 40 nm, specific surface area 30 m ² / g, hereinafter referred to as “CaCO ₃ ”) was used.

[(E) acid acceptor]

Further, magnesium oxide (manufactured by Kyowa Chemical Co., Ltd., trade name Kyowa Mag 150, 100 mesh pass, specific surface area 150 m ² / g, hereinafter referred to as “MgO”) was used as an acid acceptor.

[(F) Vulcanizing agent]

Sulfur (200 mesh pass, hereinafter referred to as "S") was used as a vulcanizing agent.

[(G) Vulcanization accelerator]

Further, as a vulcanization accelerator, benzothiazole disulfide (hereinafter, referred to as “DM”), tetramethyl thiuram disulfide (hereinafter, referred to as “TT”), and sodium salt of methylene dithiocarbamate (hereinafter, “PMTC”) ), Tetramethylthiuram monosulfide (hereinafter referred to as “TS”), N, N′-diethylthiourea (hereinafter “EU”).
R "), and 2- (4'-morpholinodithio)
Benzothiazole (hereinafter referred to as “MDB”) was used.

[(H) Vulcanization accelerator]

Zinc oxide (hereinafter, referred to as “ZnO”) and stearic acid (hereinafter, referred to as “St”) having an average particle size of 0.5 μm were used as vulcanization accelerators.

[(J) Anti-aging agent]

Further, as an anti-aging agent, 4,4'-thiobis (6-
Tertiary-butyl-3-methyl) phenol (hereinafter referred to as “TBM
P ") and a special wax (manufactured by Ouchi Shinko Chemical Co., Ltd., trade name: Sannoc, hereinafter referred to as" wax ").

[(K) plasticizer]

Trioctyl trimellitate (hereinafter referred to as "TOTM") was used as a plasticizer.

Examples 1 to 20, Comparative Examples 1 to 12 Chlorinated ethylene-propylene diameter copolymers (hereinafter referred to as "Cl-EPR"), whose types and amounts are shown in Tables 1 and 2, respectively, butadiene-based Rubber, vulcanization accelerator, anti-aging agent and vulcanization accelerator and CB (carbon black), Ca
CO ₃ (filler), MgO (acid acceptor), S (vulcanizing agent) and TO
Knead TM (plasticizer) using open roll for 20 minutes,
Each was formed into a sheet. Using a compression molding machine, the temperature of 165 ° C. and the pressure of each obtained sheet were 200 kg / cm ^2.
The vulcanized product was produced while vulcanizing for 30 minutes under the conditions described above. Each of the obtained vulcanizates was measured for tensile strength (T _B ) and elongation (E _B ) and tested for heat resistance, weather resistance, ozone resistance and flame retardancy. Table 3 shows the results.

From the results of the above Examples and Comparative Examples, it is clear that the rubber composition of the present invention is excellent not only in tensile strength (T _B ) and chemical resistance but also in heat resistance.

[Effects of the Invention] The rubber composition of the present invention exhibits the following effects (features).

(1) Good mechanical strength (for example, tensile strength).

(2) The dimensional accuracy of the molded product is excellent.

(3) Good chemical resistance and weather resistance with respect to rubber having a double bond.

(4) Good compression set.

(5) The vulcanizate or crosslinked product has excellent vulcanizability or crosslinkability.

(6) Good oil resistance.

(7) Excellent ozone resistance.

(8) Blend properties are good.

(9) Excellent extrudability.

The rubber composition of the present invention can be used in various fields to exhibit the above effects. Representative applications are shown below.

(1) Various rubber parts for automobiles (for example, packing and hose) (2) Electric wire coating (3) Parts of electrical equipment and electronic equipment (4) Various packings and sheets (5) Hose (6) Various building materials Parts (7) Roofing, pound liner

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takeshi Masukawa 3-2 Chidori-cho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Showa Electric Works Co., Ltd. Kawasaki Resin Laboratory (56) References JP-A-62-54747 (JP, A) JP-A-62-54746 (JP, A) JP-A-58-183739 (JP, A)

Claims (1)

(57) [Claims] (1) a content of (A) propylene of 15 to 40% by weight;
And the melt flow index is 0.01 to 5.0 g / 1
0 minutes and the melting peak measured by a differential scanning calorimeter is 80
Ethylene-propylene having a degree of crystallinity of 3% or more as measured by X-ray and a weight average molecular weight / number average molecular weight of 4 or more as an index of molecular weight distribution measured by gel permeation chromatography. The chlorine content obtained by chlorinating the copolymer is 20
~ 45% by weight and Mooney viscosity (ML _{1 +} 4,100 ℃)
Is a composition comprising a chlorinated ethylene-propylene copolymer having a ratio of 10 to 150 and (B) a rubber containing butadiene as a main component, and a composition ratio of the chlorinated ethylene-propylene copolymer in the composition. Is 50 to 90% by weight of the rubber composition.