JPH0822935B2 - Rubber composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rubber composition having excellent heat resistance and weather resistance, and also having good ozone resistance. More specifically, (A) chlorinated ethylene-propylene copolymer and (B)
A composition composed of natural rubber or a rubber derived from it, which not only has excellent heat resistance and weather resistance, but also has good ozone resistance, excellent oil resistance, and mechanical properties. Also relates to rubber compositions which are good.

[Conventional technology]

BACKGROUND OF THE INVENTION Natural rubber and rubber derived from natural rubber have been used in various fields such as automobile parts, industrial rubber parts, and household products. In addition, it is dissolved in a solvent and used in various fields. further,
Natural rubber and rubber derived therefrom, which are used alone, are blended with other rubbers (for example, styrene-butadiene copolymer rubber, polychloroprene rubber, chlorosulfonated polyethylene rubber) to obtain the above-mentioned components. It is widely used in various fields, and facilitates the improvement of mechanical strength, electrical characteristics, compression set characteristics, etc.

[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. In addition, in the field of parts such as automobiles and home appliances, natural rubber and rubber derived therefrom (hereinafter referred to as "natural rubber") are widely used, but in recent years, flame resistance, heat resistance, weather resistance, etc. However, there is a drawback that natural rubber and the blends as described above are not sufficiently satisfied.

As described above, the blended product as described above has a high mechanical strength,
One of the physical properties such as compression set, weather resistance and flame retardancy is excellent, but other properties are not sufficiently satisfied, and it is possible to obtain a composition having a balance of these properties. could not.

From the above, the present invention does not have these drawbacks, that is, not only excellent mechanical strength, but also to obtain a composition (mixture) having excellent properties such as heat resistance, weather resistance and flame retardancy. It is another object of the present invention to obtain a composition in which the above-mentioned drawbacks of the commonly used thermoplastic elastomers are improved.

[Means and Actions for Solving the Problems]

According to the invention, these problems are according to (A) the content of propylene is from 15 to 40% by weight, and the melt flow index (according to JIS K7210,
Measured under 14 conditions, hereinafter referred to as "MFR") 0.01-5.0g / 10
Min., Melting peak measured by differential scanning calorimeter is 80 ° C.
Above, the crystallinity measured by X-ray is 3% or more, and the weight average molecular weight (which is an index of the 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 and a Mooney viscosity (ML _{1 + 4} , 100 ° C) of 10 to 150 obtained by chlorinating a propylene copolymer. A rubber composition comprising: a polymer; and (B) a natural rubber or a rubber derived therefrom, wherein the composition ratio of the chlorinated ethylene-propylene copolymer in the composition is 40 to 90% by weight. The present invention can be specifically described below.

(A) Chlorinated Ethylene-Propylene-Based Copolymer In producing the chlorinated ethylene-propylene-based copolymer used in the present invention, the raw material ethylene-
The propylene content of the propylene-based copolymer is 15 to 40% by weight, preferably 18 to 40% by weight, and more 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 carried out using an ethylene-propylene-based copolymer in excess of 40% by weight, the particles of the chlorinated ethylene-propylene-based copolymer obtained during chlorination become large and become agglomerated in the reaction system. Is not preferable.

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 viscosity (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 the Mooney viscosity of less than 10 ethylene-propylene copolymer is chlorinated,
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 used as a differential scanning calorimeter (DSC).
The melting peak measured in C) is 80 ° C. or more, and the crystallinity measured by X-ray 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 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
If the chlorination is carried out using an ethylene-propylene-based copolymer of less than 0.1%, a chlorinated product is formed at the chlorination stage, and similarly 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.

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 state, it is preferable to add a small amount of an emulsifying agent or suspending agent. In this case, 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-based copolymer of the present invention, it is desirable to carry out chlorination in the above-mentioned aqueous suspension by the following three methods.

The first method is the ethylene used in the first step
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
Chlorination of 20 to 60%, in the second step is a temperature 10 ° C or higher higher than the chlorination temperature in the first step, but 5 to 15 ° C higher than the melting point of the ethylene-propylene copolymer.
It is a method of performing the remaining chlorination at a low temperature.

Also, the second method is at least 25 ° C above the melting point of the ethylene-propylene copolymer used in the first step.
Although the temperature is lower by ℃, chlorination of 20-60 wt% of the total chlorination amount at a temperature higher than 50 ℃, in the second stage up to a temperature 1-7 ℃ higher than the melting point of the ethylene-propylene copolymer The temperature is raised and annealed at this temperature for 10 to 60 minutes without introducing chlorine, and in the third stage, 2 to 25 ° C higher than the melting point of the ethylene-propylene copolymer.
It is a method of performing the remaining chlorination at a low temperature.

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, the chlorination is carried out at a temperature lower than the melting point of the ethylene-propylene copolymer but lower than the melting point by 2 ° C. or less.

The chlorine content of the chlorinated ethylene-propylene copolymer used in the present invention thus obtained is 20.
~ 45 wt% (preferably 20-42 wt%, suitably 25
~ 42% by weight). If the chlorine content of this 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, 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.

The Mooney viscosity of a large rotor at a temperature of 100 ° C. is 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) Natural rubber, etc. Further, the Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the natural rubber used in the present invention is usually 5 to 200 in view of kneading property and moldability and strength of the composition, Especially 10
~ 180 is preferred. Representative examples of the natural rubber include
Latex raw rubber collected from Hevea brasiliensis, natural rubber consisting of smock sheets, grafted natural rubber made by grafting monomers such as methyl methacrylate, styrene and acrylonitrile to the natural rubber, grafted natural rubber Modified natural rubber to which maleic anhydride or thiolic acid is further added, chlorinated natural rubber obtained by dissolving natural rubber in a solvent and blowing chlorine gas to react, natural rubber directly or a strong acid in its solution (for example, RSO ₃ X, Lewis acid) and the like are cyclized natural rubber-like substances produced by cyclization. The natural rubber and the like are available from Kamihara, Kawasaki, Kitajima, and Furuya's “Synthetic Rubber Handbook” (Asakura Shoten, published in 1960, pages 348 to 352, and “Rubber / Elastomer Utilization Notes” (Industrial Research Committee, 60) Annual publication) Page 35 to 46.

(C) Composition ratio The composition ratio of the chlorinated ethylene-propylene copolymer in the composition of the present invention is 40 to 90% by weight, and particularly preferably 45 to 90% by weight. The composition ratio of the chlorinated ethylene-propylene copolymer in the composition is 40% by weight.
When it is less than 1, the weather resistance, flame resistance and ozone resistance of the resulting composition are not good. On the other hand, when it exceeds 90% by weight, oil resistance and flame retardancy are good, but it is meaningless to produce a composition.

(D) Mixing method, vulcanization method, molding method, etc. Although the composition (mixture) of the present invention can be obtained by uniformly mixing the above substances, dehydrochlorination which is generally used in the rubber industry is also used. Inhibitors, sulfur, sulfur donors, vulcanization accelerators, vulcanization accelerators, organic peroxides, crosslinking aids, plasticizers, stabilizers against oxygen, ozone, heat and light (ultraviolet), scotch inhibitors, Additives such as an anti-adhesive agent, a conversion agent, a reinforcing agent, a foaming aid, a flame retardant, a flame retardant aid, a lubricant and a coloring agent may be added depending on the purpose of 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 molded into a desired shape using an extrusion molding machine, an injection molding machine, a compression molding machine, a transfer molding machine or the like which is 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 rate of tensile strength and the residual rate of tensile elongation were measured in the same manner. Furthermore, the ozone resistance test was conducted in accordance with JIS K6301 at a temperature of 40 ° C, an elongation of 20%, and an ozone concentration of 50 pph.
After standing for 200 hours under static conditions of m and m, the presence or absence of cracks was observed. The flame retardancy was measured according to UL-94 method, which is a safety standard of Underlight Laboratory (UL).

The chlorinated ethylene-propylene copolymers used in Examples and Comparative Examples, natural rubber, carbon black, acid acceptor, crosslinking agent, vulcanizing agent, crosslinking aid, vulcanization accelerator, plasticizer, The types and physical properties of fillers, antioxidants, lubricants and vulcanization acceleration aids are shown below.

[(A) Chlorinated Ethylene-Propylene Copolymer]

As a chlorinated ethylene-propylene copolymer, an ethylene-propylene copolymer having an propylene content of 22% by weight in an aqueous suspension state and a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 115 ( MFR 1.0g / 10min, melting point 120 ℃, below "EPR
(1) ") 10 kg is charged and stirred at 50-90 ℃
In the above temperature range, the copolymer was chlorinated until the chlorine content of the copolymer reached 18.2% by weight (first stage chlorination). Then,
The temperature of the reaction system was raised to 121-125 ℃, and the introduction of chlorine was stopped within this temperature range and annealing was performed for 30 minutes (second-stage annealing). Then, the reaction system was cooled and 95
Chlorinated ethylene with a Mooney viscosity (ML _{1 + 4} , 100 ° C) of 42.0, chlorinated until the chlorine content reaches 35.4 wt% (third stage chlorination) in the temperature range of ~ 118 ° C.
Propylene-based copolymer (MFR 10.0g / 10 minutes, referred to as "CIEPR
(A) ") and 10 kg of the above EPR (1) were charged in the same manner as above, and chlorinated with stirring at a temperature range of 50 to 90 ° C until the chlorine content of the copolymer reached 18.2% by weight. (First stage chlorination). The reaction was then heated to 105-115 ° C. and chlorinated in this temperature range until the chlorine content was 27.1% by weight (second stage chlorination). Then 11
Chlorinated in the temperature range of 8 to 120 ° C until the chlorine content reaches 30.2% by weight (third stage chlorination), Mooney viscosity (ML _{1 + 4} ,
A chlorinated ethylene-propylene copolymer (FR11.0 g / 10 minutes, hereinafter referred to as "CIEPR (B)") having a temperature of 61 at 100 ° C) was used.

[(B) Natural rubber, etc.]

Also, as natural rubber, Mooney viscosity (ML _{1 +} 4,10
Natural rubber having a temperature of 90 ° C. of 90 [variety Lid Smoked Sheets, specific gravity 0.93, microstructure (isoprene unit), cis-1,4 97%, number average molecular weight 760,000 g / mol, hereinafter “RSS #
3 ”] and grafted natural rubber (trade name: Plantation Latex Co., trade name, Huber Price MG rubber, specific gravity 1.02, graft component methyl methacrylate, hereinafter referred to as“ MG49 ”). The RSS ^# 3 used was one in which the Mooney viscosity (ML _{1 + 4} , 100 ° C.) was adjusted to 50 by passing it 15 times using a roll with a roll temperature set to 50 ° C. and a Nippo set to 5 mm.

[(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) Acid acceptor]

As an acid acceptor, tribasic lead sulfate (manufactured by Koseisha, trade name TS, average particle size 2.08 μm, density about 7.0 g / cm ³ , hereinafter referred to as “tribase”) and magnesium oxide (Kyowa Chemical Co., Ltd.) Made by Kyowamag 150, 100 mesh path, specific surface area 150 m ² / g, hereinafter referred to as “MgO”.

[(E) Crosslinking agent, vulcanizing agent]

Further, n-butyl-bis (tertiary-butylperoxy) valerate (hereinafter referred to as "V") as a crosslinking agent,
Further, powdered sulfur (200 mesh pass, hereinafter referred to as "S") was used as a vulcanizing agent.

[(F) Crosslinking aid, vulcanization accelerator]

Also, triallyl isocyanurate (hereinafter referred to as "TAIC") as a crosslinking aid, and sodium salt of pentamethylene dithiocarbamate (hereinafter referred to as "PMTC") and tetramethylthiuram disulfide (hereinafter referred to as "vulcanization accelerator") "TT"), diethyl thiourea (hereinafter "EUR"), tetramethylthiuram monosulfide (hereinafter "TS") and dibenzothiazyl disulfide (hereinafter "DM") are used. did.

[(G) Plasticizer]

Further, trioctyl trimellitate (hereinafter referred to as "TOTM") was used as a plasticizer.

[(H) Filler]

As the filler, fatty acid-treated calcium carbonate (manufactured by Shiraishi Kogyo Co., Ltd., trade name Hakueka CC, average particle size 40 nm, specific surface area 31 m ^{2 /} g, pH 8.8, hereinafter referred to as “CaCO ₃ ”) was used. .

[(J) Anti-aging agent]

Furthermore, as an antiaging agent, poly (2,2,4-trimethyl-1,2-dihydroquinoline) (hereinafter referred to as "2,2,4")
It was used.

[(K) Vulcanization acceleration aid]

Further, 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 acceleration aids.

[(L) Lubricant]

Further, paraffin wax (hereinafter referred to as “wax”) was used as a lubricant.

Examples 1 to 11 and Comparative Examples 1 to 5 Chlorinated ethylene-propylene copolymers (hereinafter referred to as "Cl-EPR"), the amounts and types of which are shown in Tables 1 and 2, respectively. Acid acceptor, such as natural rubber
Cross-linking agent, vulcanizing agent, cross-linking auxiliary agent, vulcanization accelerator and vulcanization accelerator auxiliary agent, and carbon black (CB) and filler (CaCO
₃ ), anti-aging agent (2,2,4) plasticizer (TOTM) and lubricant (wax) were kneaded using an open roll for 20 minutes at room temperature (about 20 ° C), and each was formed into a sheet. The temperature of each of the obtained sheet materials was measured by using a compression molding machine.
A vulcanized product and a crosslinked product were produced by vulcanizing or crosslinking for 30 minutes at 165 ° C. and a pressure of 200 kg / cm ² . Each of the obtained vulcanized products and crosslinked products was tested or measured for tensile strength, elongation, ozone resistance (the time when cracks occur is shown in Table 3), weather resistance and flame retardancy. The results are shown in Table 3.

From the results of the above Examples and Comparative Examples, the rubber composition of the present invention not tensile strength (T _B) and only has excellent for ozone resistance, it is apparent that excellent also heat resistance.

〔The invention's effect〕

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) Excellent chemical resistance and weather resistance.

(4) Good compression set.

(5) The vulcanized or crosslinked product has excellent vulcanization or crosslinkability.

(6) Oil resistance is good.

(7) Permanent elongation is excellent.

(8) Good blendability.

(9) Excellent flame retardancy.

(10) Good heat resistance.

The rubber composition of the present invention can be used in various fields in order to exert the above effects. Typical uses are shown below.

(1) Various rubber parts for automobiles (eg packing,
Hose) (2) Electric wire coating (3) Parts for electric and electronic devices (4) Various packings and sheets (5) Hoses (6) Various building material parts (7) Roofing, pond liner

Claims (1)

[Claims] 1. The content of (A) propylene is 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 temperature of ℃ or more, a crystallinity of 3% or more measured by X-ray, and a weight average molecular weight / number average molecular weight of 4 or more, which is an index of the 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 ℃)
A composition comprising a chlorinated ethylene-propylene copolymer having 10 to 150 and (B) natural rubber or a rubber derived therefrom, wherein the composition of the chlorinated ethylene-propylene copolymer occupies in the composition A rubber composition having a proportion of 40 to 90% by weight.