JPS6173751A - Rubber composition having excellent durability - Google Patents

Abstract

PURPOSE:To provide the titled rubber compsn. which has excellent resistance to heat and oils and is inexpensive, by blending a peroxide with a rubber component mixture. CONSTITUTION:A rubber component consisting of 20-80pts.wt. ethylene/vinyl carboxylate/acrylate copolymer such as Denka ER-3400P (a product of Denki Kagaku Kogyo K.K.) and 80-20pts.wt. ethylene/propylene (1 diene) copolymer such as EP0045 (a product of Mitsui Sekiyu Kagaku K.K.) is used. 1.5-5pts.wt. peroxide such as 1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane is blended with 100pts.wt. said rubber component.

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention is expensive but has excellent durability, and is being applied to the field of industrial products that require a high degree of durability, such as functional parts for automobiles. ethylene-vinyl carboxylate-acrylic ester copolymer, and ethylene-propylene copolymer or ethylene-vinyl carboxylate copolymer, which is inexpensive and has moderate durability.
It was obtained as a result of research to provide a relatively inexpensive and more durable material for industrial products by mixing propylene-diene monomer copolymers. 100 parts by weight (hereinafter often referred to as EPR) of a mixture of a polymer (hereinafter often referred to as ER) and an ethylene-propylene copolymer or an ethylene-propylene-diene monomer copolymer (hereinafter often referred to collectively as EPR) expressed as EPM or EPDM. phr), the ER is 20 phr or more and 80 phr or less, and the EPR is 20 phr or more and 80 phr or less,
1-5 to 5 peroxide per 100 phr of this mixture
This objective was achieved by incorporating phr.

(Prior art) As mentioned above, EPR has been used in large quantities in recent years because it is an inexpensive rubber with moderate durability.
Because it has a woody disadvantage of extremely poor oil resistance,
EPR could not be used in fields that also required oil resistance.

Therefore, attempts have been made to blend EPR and rubber with excellent oil resistance, but since EPR is non-polar and rubber with excellent oil resistance is highly polar, (1) it is difficult for the two to mix well. (2) It is known that it is extremely difficult to mix the vulcanizing agent equally into both and cause the vulcanization reaction to occur equally. Due to the difficulties in (1) and (2), the performance of the mixture of both deviates significantly from the so-called predicted value obtained by proportional allocation from the mixing ratio of both and the performance of both single components, resulting in practical performance. Usually it is not possible.

Recently, a material (for example, JSRNE manufactured by Japan Synthetic Rubber Co., Ltd.) that overcomes this difficulty and is a mixture of EPR and NB'R has been announced.

(Problem to be solved by the invention) However, in a blend of EPR and NBR, NBR is EPR.
Since the heat resistance and ozone resistance are inferior to that of EPR, the blend has the disadvantage that it cannot provide a rubber material that exceeds the heat resistance and ozone resistance of EPR.

ER has much better heat resistance and ozone resistance than NBR, and oil resistance is equivalent to NBI'l, so if a mixture of EPR and ER can have both properties, it will have better heat resistance and ozone resistance than EPR. It is possible to provide a rubber material that is excellent in resistance to non-polar liquids, is cheaper than ER, and has excellent resistance to non-polar liquids.

(Means for Solving the Problems) The present invention comprises 20 parts by weight or more and 80 parts by weight or less of an ethylene-vinyl carboxylate-Nisder acrylate copolymer and an ethylene-propylene copolymer or an ethylene-propylene-diene monomer copolymer. A rubber composition characterized in that 1.5 parts by weight of peroxide and 5 parts by weight or less of H are blended with 100 parts by weight of a mixture of 20 parts by weight or more and 80 parts by weight or less.

In order to create a rubber material with excellent heat resistance and non-polar liquid resistance by mixing ER with EPR, it is basically necessary that ER itself is a rubber-like substance with excellent heat resistance and non-polar liquid resistance. ,
ER requires ethylene in order for the copolymer to be a rubber-like substance at room temperature, and vinyl carboxylate and acrylic ester in order to have heat resistance, non-polar liquid resistance, and cold resistance.

As for ER, ethylene is 2 parts by weight or more and 30 parts by weight or less,
A copolymer containing 15 to 80 parts by weight of vinyl carboxylate and 20 to 80 parts by weight of acrylic ester provides a preferred rubbery material.

ER can be obtained by conventional emulsion polymerization or suspension polymerization. Typical examples of the vinyl carboxylate are vinyl acetate and vinyl propionate, and vinyl acetate is preferable because it can be produced industrially at the lowest cost and provides the ER with the performance of non-polar liquid resistance.

Acrylic ester is represented by formula (1) or (2),
Typical compounds of formula (1) include methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, and compounds of formula (2) include methoxymethyl acrylate and methoxy acrylate. Ethyl, ethoxymethyl acrylate, and ethoxyethyl acrylate are common.

Formula (1) r:l+2=CHCOO-R.

(However, R1 is an alkyl group having 3 to 8 carbon atoms.) Formula (2) CI+2=CHCOO-R2-R3 (However, R2 is an alkylene group having 1 to 4 carbon atoms, and R3 is an alkoxy group having 1 to 4 carbon atoms. (It is an alkyl group.) The ratio of both EPR and FR in the mixture is 10
At 0 phr, the ER is 20 phr or more and 80 phr or less, and when the ER is less than 20 phr, the heat resistance of the mixture
The improvement in resistance to non-polar liquids is insufficient, and above 80 phr, the objective of obtaining a relatively inexpensive composition is gradually defeated, and the resistance to polar liquids is compromised.

Any peroxide commonly used for rubber vulcanization can be used, but dialkyl peroxide-based peroxides are most suitable. This type of peroxide is 1,1 g (t
butylperoxy) 3.3゜5 trimethylcyclohexane, n-butyl-4゜4-bis(t-butylperoxy)valerate, dicumyl peroxide, di-t-butylperoxydi-isopropylbenzene, 2,5 -dimethyl-2,5-di(t-butylperoxy)hexano,
Examples include 2,5-dimethyl and -2,5-di(t-butylperoxy)hexyne-3.

Peroxide is required at 1.5 to 5 phr per 100 phr of total EPR and ER. If it is less than 1.5 phr, the degree of vulcanization is insufficient and it is difficult to obtain practical strength. If it exceeds 5 phr, the elongation of the vulcanizate will decrease due to excessive vulcanization.

The crosslinking of the mixture is more effective when a polyfunctional monomer is used in combination, and the amount is more than 100% of EPR (!: ER mixture 100
An appropriate amount is 15 phr or less.

Excess polyfunctional monomer is undesirable because it causes the crosslinked product to lose flexibility. Trimethylolpropane trimethacrylate is the most effective polyfunctional monomer, followed by triallyl isocyanurate, triallyl cyanurate, and triallyl trimellitate. Sialiftale-1-1
1,2-polybutadiene and the like are also applicable. ``Using a radical scavenger and a thiourea derivative in combination is effective in balancing the physical properties of the crosslinked product.'' The radical scavenger should be used at a rate of 3 phr or less per 100 phr of a mixture of EPR and ER, and the thiourea derivative at a rate of 5 phr. It is recommended to use the following: If a large amount of radical scavenger is used, peroxide is wasted and the purpose of balancing the physical properties of the crosslinked product is lost. If a large amount of thiourea derivatives are used, the opposite effect will occur in that the physical properties of the crosslinked product will deteriorate. It is desirable to use them alone or in combination within the above range.

Polymerization inhibitors and anti-aging agents are used as radical scavengers.
Representative examples include phenothiazine and 2°6-di-t-butyl-p-cresol.

In addition, various fillers, plasticizers, processing aids, and stabilizers used in the rubber industry can be added to the mixture depending on the intended use of the mixture.

The preparation of the mixture can be easily accomplished by adding the two together in the same way as the rubber alone into a mixing roll or closed mixer used in the rubber industry, and it can be said that one of the features of the present invention is that no special mixing operation is required.

(Function) In a mixture of ER and EPR, since ER is a copolymer with strong polarity, a fine compatibility of ER and EPR cannot be achieved, and the tensile properties of the vulcanizate are determined by the tensile properties of the two alone and the mixing ratio. It often falls short of the level predicted by arithmetic. This fact should be eliminated in the first place, since there is no advantage in mixing the two. However, in the present invention, although the physical properties of the mixture do not reach the intermediate level between the two, they do not decrease to the extremely low tensile strength that often occurs when compatibility is poor, and are maintained at a level that does not cause problems in practical soil. This is one feature, and furthermore, although the physical properties before aging do not show the advantages of mixing as mentioned above, the physical properties after exposure to hot air, the volume change rate and cold resistance after immersion in high-temperature oil, The greatest advantage of the present invention is that improvements can be observed in response to mixing.

(Example) The effectiveness of the present invention will be specifically explained using Examples below. The blending amount is in parts by weight.

Examples 1 to 3 Comparative Examples 1 to 2 Denka E R-3400P manufactured by Denki Kagaku Kogyo ■ as ER
A compound was prepared using EPOO45 manufactured by Mitsui Petrochemical Co., Ltd. as XEPR according to the compounding recipe shown in Table 1, and a rubber test was conducted. The results are shown in Table-1.

In addition, kneading is performed using an 8-inch roll, and press vulcanization is performed at 170°C.
After 10 minutes at 150° C., post-vulcanization was performed at 150° C. for 4 hours in a gear oven to prepare a test piece.

The rubber test was based on JIS K6301.

As shown in Examples 1 to 3, the tensile strength of the composition of the present invention, which is a mixture of ER and EPR, is lower than expected from the mixing ratio, but is within the practical range. The tensile strength after heat aging is different from the physical properties before aging, and is at the level expected from the mixing ratio of ER and EPR, and the effect of mixing is clearly visible, and the tensile strength after aging is improved by mixing ER. It will be done.

In addition, the oil resistance of the mixture within the scope of the invention exhibits the mixing effect of ER and provides oil resistance superior to that of EPR alone.

Therefore, the composition of the present invention can provide a useful material that is cheaper than ER and has better oil resistance and heat resistance than EPR.

The composition of the present invention is a suitable material for various industrial parts (belts, hoses, gaskets, boots, etc.) that require both lubricant resistance and heat resistance, especially automobile parts.

Examples 4 to 6 Comparative Examples 3 to 4 As ER, ER, -840IP manufactured by Denki Kagaku Kogyo @ was used, and E
A composition was prepared and tested in the same manner as in Examples 1 to 3 using EP-0045 manufactured by Mitsui Petrochemicals as PR. The formulation and results are shown in Table 2.

The tensile strength before aging of the compositions of Examples 4 to 6 does not reflect the physical properties of each of EPR and ER, and is not at the level expected from the mixing ratio, but the tensile strength after heat aging does not reflect the physical properties of EPR and ER. The effect of ER mixing clearly appears, and the tensile strength of the mixtures (Examples 4 to 6) is improved compared to EPR alone (Example 5). In addition, the oil resistance was also 1. compared to Comparative Example 2. The improvement is significant. Furthermore, the durability against polar liquids (equal volume mixture of ethylene glycol/water) is improved compared to ER alone (Comparative Example 3).

The composition of the present invention has an excellent balance of oil resistance and polar liquid resistance, and has a high level of heat resistance and cold resistance, so it can be used not only for ordinary industrial parts but also for heat resistant hoses, heater hoses, boots, hose covers, etc. , provides materials suitable for fields that require oil resistance, liquid resistance, and cold resistance.

Examples 7-9 Comparative Examples 4-5 ER-8401P manufactured by Denki Kagaku Kogyo ■.

Using EPT3045 manufactured by Mitsui Petrochemical Co., Ltd. as EPR,
Compositions were prepared according to the formulation shown in Table 3, and Examples 1 to 3
The test was conducted in the same manner. The results are shown in Table-3.

The compositions of the present invention (Examples 7 to 9) have improved oil resistance compared to plain EPR (Comparative Example 5), and although the tensile properties before heat aging are inferior to those of plain EPR, the tensile properties after heat aging are Characteristics are EPR
It can be seen that this is a significant improvement over the plain taste. (EP R,
As for the il-taste, a burn occurred when the test piece was mounted on the tensile testing machine. ) The composition of the present invention is also used in the field of industrial products that require both heat resistance and oil resistance, such as belts, hoses,
It provides materials suitable for gaskets, dust covers, seals, etc.

Examples 10 to 13 EPR using ER-840IP manufactured by Denki Kagaku Kogyo ■ as ER
Using EPDMEP 1045 manufactured by Mitsui Petrochemical Co., Ltd., a mixture was prepared according to the formulation shown in Table 4, and a rubber test was conducted. The results are shown in Table 4.

In addition, kneading is performed using an 8-inch roll and press vulcanization is performed at 170°C.
After vulcanization was performed for 10 minutes at 150° C. in a gear oven for 4 hours, a test piece was prepared.

The rubber test was based on JIS K6301.

The ingredients used in the Examples and Comparative Examples are as follows.

1) Anti-aging agent Naugard manufactured by Uniroyal
4452) Manufactured by Tokai Carbon Co., Ltd. 1 (Al"l, S Carbon Bra, Tsuku 3) Nippon Silica Co., Ltd. White Carbon 4) Nippon Unicar Co., Ltd. NUC silane force/twisting agent A172 5) Manufactured by Adeka Argus Co., Ltd. Ester plasticizer 6) Nippon Oil & Fats Co., Ltd. Peroxide n-buty JL/-4゜4-
Bis-t-butyl-oxyvalerate 40% product 7) Manufactured by Dainippon Ink Co., Ltd. Ester plasticizer 8) Manufactured by Nihon Yushi Co., Ltd. Peroxide dicumyl-oxide 40
% Product Patent Applicant: Denki Kagaku Kogyo Co., Ltd. Procedural Amendment Written on October 18, 1980 Manabu Shiga, Commissioner of the Patent Office 1, Indication of Case 1982 Patent Application No. 196199 2, Invention Name Durability Excellent rubber composition 3, relationship with the case of the person making the amendment Address of the patent applicant ■100 Detailed description of the invention in the specification 1-4-1 Yurakucho, Chiyoda-ku, Tokyo 5, Contents of the amendment + 11 Specification On page 9, lines 4-5, "mixing roll" is corrected to "mixing roll."

(2) “Mixing” on page 10, line 3 of the specification is “mixing ratio”
Correct to.

Claims (1)

[Claims] Mixture 1 of 20 to 80 parts by weight of ethylene-vinyl carboxylate-acrylic acid ester copolymer and 20 to 80 parts by weight of ethylene-propylene copolymer or ethylene-propylene-diene monomer copolymer
1. A rubber composition comprising: 1.5 parts by weight or more and 5 parts by weight or less of peroxide per 00 parts by weight.