JPS61268743A - Curing rubber composition - Google Patents

Abstract

PURPOSE:To obtain the titled composition of enhanced mechanical strength, by incorporating a rubber with specified amount of specific modified rubber compounding oil prepared from paraffin-based mineral oil, polyethylene and maleic anhydride. CONSTITUTION:The objective composition can be obtained by incorporating (A) 100pts.wt. of an ethylene-propylene rubber with (B) 30-200 (pref. 50-150) pts.wt. of a modified rubber compounding oil prepared by reaction, in the presence of a radical generator, between (i) paraffin-based mineral oil with a density 0.86-0.92, dynamic viscosity (at 40 deg.C) 5-800 and aniline point 70-145 deg.C, (ii) polyethylene with a molecular weight 10,000-500,000, and specific gravity 0.90-0.98 and (iii) maleic anhydride. Said compounding oil has the following characteristics: 1. the amount of the maleic anhydride added to the polyethylene ...0.5-2wt%, 2. ratio of extinction coefficient at 1,778cm<-1> to that at 840cm<-1> in the infrared absorption spectrum ... 0.1-1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a vulcanized rubber composition, and more particularly to a vulcanized rubber composition with excellent mechanical strength.

[Technical background of the invention and its problems] A maleated polyolefin wax obtained by rag-grafting a maleic M compound onto a polyolefin in wax is added to an ethylene propylene rubber with a vulcanizing agent, a vulcanization aid,
Vulcanized rubber compositions blended with a vulcanization accelerator are known (see Japanese Patent Publication No. 51-8129), and vulcanized rubber compositions blended with process oil grafted with mineral oil are also known. (Refer to JP-A-58-183150 and JP-A-3411) Furthermore, compositions in which a grafted soft polyolefin grafted with an unsaturated carboxylic acid is used as a rubber compounding oil are also known.

However, in the above-mentioned prior art, since various solvents are required when compounding these rubber compounding oils into rubber, a process of recovering the solvents is inevitably necessary, and furthermore, the obtained In vulcanized rubber compositions, a localized high-density crosslinking reaction proceeds to produce an insoluble gel substance, resulting in the disadvantage that it is difficult to produce a homogeneous composition.

In particular, the latter disadvantage is a cause of lowering the mechanical strength of the vulcanized rubber composition and restricting its field of application, and therefore improvement thereof is strongly desired.

[Object of the Invention] An object of the present invention is to provide a vulcanized rubber composition in which the above-mentioned disadvantages are eliminated and the mechanical strength is improved by incorporating a modified rubber compounding oil described below.

[Summary of the Invention] In order to achieve the above object, the present inventors conducted intensive research on the rubber compounding oil to be blended during the production of rubber compositions, and as a result selected ethylene propylene rubber as described below as the rubber component. The inventors discovered that the mechanical strength of the resulting vulcanized rubber composition is significantly improved when the modified rubber compounding oil described below is blended with it, leading to the development of the vulcanized rubber composition of the present invention. .

That is, the vulcanized rubber composition of the present invention is composed of 100 parts by weight of ethylene propylene rubber, paraffinic mineral oil, polyethylene, and maleic anhydride, and the total addition heat of maleic anhydride to polyethylene is 0.5 to 100 parts by weight. 2% insect mass and 17 in the infrared absorption spectrum
The ratio of the absorbance at the 78 cm-' position to the absorbance at the 840 c++-' position is within the range of 0.1 to 1.0, and the modified rubber compounding oil is blended with 30 to 200 overlapped parts. Characterize.

The most important feature of the composition of the present invention is that the modified rubber compounding oil described below is blended with the ethylene propylene rubber.

This modified rubber compounding oil is obtained by reacting paraffinic mineral oil, polyethylene, and maleic anhydride in the presence of a radical generator, and the amount of maleic anhydride added to the polyethylene is 0.5 to 0.5% of the total amount of maleic anhydride added to the polyethylene. 2% by weight, and the absorbance at 1778 cm 1 position M (01778) and the absorbance at 840 cm m-' position (01778) in the infrared absorption spectrum.
0840) (0177B/0840) is 0.1
It is a modified rubber compounding oil within the range of ~1.0. When the amount of maleic anhydride added is 0.5% by weight based on the weight of the entire compounded oil, no effect of improving the mechanical strength of the obtained rubber compound can be obtained; If it is added, not only no improvement in mechanical strength can be obtained, but also an increase in bleed.

Also, = 01778/0840 is less than 0.1.
7) The effect of improving the 100% tensile modulus is slight;
If it exceeds 1.0, the elongation at break improves, but on the other hand, the tensile modulus decreases as the ratio of the infrared absorption spectrum is 01778/
It is not preferable because it starts to decrease at 0840.

The base oil in the modified rubber compounding oil according to the present invention is a paraffinic mineral oil. This mineral oil is generally the following JI
Those having the properties shown in Table 1 measured by the method specified in the S standard are suitable.

Table 1 Among these properties, specific gravity, kinematic viscosity, and aniline point are important factors.For example, if the specific gravity is higher than the upper limit in Table 1, the weather resistance is significantly inferior, whereas if it is lower than the lower limit, the viscosity is low. Mineral oil with a kinematic viscosity higher than 800 cSt (40°C) becomes too viscous, making it difficult to mix uniformly into rubber; Smaller mineral oils result in greater bleed of the resulting rubber product. Furthermore, mineral oils with an aniline point higher than 145°C have a lower compatibility with rubber and increase bleeding, while mineral oils with an aniline point lower than 70°C are undesirable because they result in a decrease in the properties of the resulting rubber product, such as weather resistance.

Among these paraffinic mineral oils, secondary water-containing oils such as Diana Process Oil PW38Q (trade name, manufactured by Idemitsu Kosan) are particularly suitable.

Next, polyethylene has a viscosity average molecular weight of 10,000 to 500,000, for example. Specific gravity is 0.90-0.98
Polyethylene having properties such that the melting index (Ml: g/10 min) is 0.1 to 30 is preferred, and in particular, polyethylene having a viscosity modulus of 20,000 or more is preferred, and this value is less than 10,000. When this is used, the hardness of the obtained rubber product decreases and at the same time bleeding increases. However, polyethylene with a viscosity average molecular weight that is too large has a lower solubility in the paraffinic mineral oil, so the upper limit is preferably 500,000, particularly 50,000 to 300,000.

Among these polyethylenes, Idemitsu polyethylene LO1148 (trade name) whose properties are shown in Table 2.

LLDPE manufactured by Idemitsu Petrochemical Co., Ltd. and Idemitsu Polyethylene 4
40M (trade name, same as above) high density polyethylene is particularly suitable.

Table 2 The modified rubber compounded oil according to the invention is obtained by reacting the paraffinic mineral oil described above, polyethylene, and maleic anhydride in the presence of a radical generator described below to add a predetermined amount of maleic anhydride to polyethylene. It is.

During this reaction, polyethylene is first dissolved in paraffinic mineral oil.The operation is usually carried out at a temperature of 180 to 250°C.The amount of polyethylene dissolved is 5 to 35 parts by weight per 100 parts by weight of paraffinic mineral oil. Set. If the dissolved amount is less than 5 parts by weight, the rubber elasticity of the obtained rubber product at low temperatures will decrease;
This is because if the amount exceeds 5 parts by weight, the mechanical strength of the rubber product will decrease and bleeding will increase.

Next, the obtained solution is once cooled to 150 to 80"O, and then maleic anhydride and a radical generator are added thereto. The amount of maleic anhydride added is equal to 1 % of paraffinic mineral oil.
The content is set at 0.5 to 5 parts by weight relative to 0.00 parts by weight. 0.
If the amount is less than 5 parts by weight, the amount of maleic anhydride groups added to polyethylene in the obtained rubber compounding oil will be less than 0.5% by weight, and as a result, the mechanical properties of the rubber compounded with the rubber compounding oil will decrease. The strength improvement effect decreases, and if it exceeds 5 parts by weight, the amount added to polyethylene will exceed 2% by weight, which improves the elongation at break of the rubber, but at the same time causes a decrease in the tensile modulus. It is. Preferably 0.
02 to 0.4 parts by weight.

Any radical generator may be used as long as it can promote radical polymerization in the above-mentioned three-component system.
For example, dicumyl peroxide, t-butylcumyl peroxide, 1-3-bis(t-butylperoxy-
isopropyl)-benzene, 2,5-dimethyl-2,5
- dialkyl peroxides such as di(t-butylperoxy)-hexane, dibutyl peroxide, 2,5-dimethyl-2,5-(t-butylperoxy)-hexyne-3, 1,4,4- Trimethylbenzene 2-
Hydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide,
Specific examples include organic peroxides such as hydroperoxides such as t-butyl hydroperoxide; and inorganic peroxides such as hydrogen peroxide, nitrous acid, nitric acid, and potassium permanganate. These organic peroxides or inorganic peroxides may be used alone or in an appropriate combination of two or more.

Particularly preferred is dicumyl peroxide.

These radical generators are preferably set at 0.05 to 2 parts by weight per 100 parts of paraffinic mineral oil.If this amount is 0.05 parts of heavy acid, radical polymerization will proceed effectively. On the other hand, if the amount exceeds 2 parts by weight, not only will the addition efficiency decrease, but also the rubber will become excessively hardened as the rubber heats up, causing adverse effects on heat aging properties. Preferably it is 0.1 to 1 part by weight.

The radical polymerization reaction is preferably carried out under an inert gas, at a temperature of 135-155°C, and a reaction time of 1-10°C.
Preferably, it is time.

As described above, if the product obtained by radical polymerization is subjected to a stripping treatment to separate and remove peroxide decomposition components and unbound maleic anhydride, a rubber compounding oil that is effective for use in the present invention can be obtained. is obtained. In addition, the conditions for the stripping treatment are preferably such that unreacted maleic anhydride in the product becomes substantially zero, and 1 to 2 + smHg.
, a temperature of 185 to 225°C for 1 hour, preferably 1 to 5 hours.

The vulcanized rubber composition of the present invention is characterized in that 30 to 200 parts by weight of the above-mentioned modified rubber compounding oil is blended to 1 part of the above-mentioned ethylene propylene rubber +00fi. If this amount is less than 30 parts by weight, not only will the mechanical strength of the resulting vulcanized rubber composition not improve, but the kneading operation will not be able to be performed smoothly, leading to a decrease in moldability.
In addition, if the number of trains exceeds 200, a bleed phenomenon will begin to occur. Preferably it is 50 to 150 parts by weight.

To the vulcanized rubber composition of the present invention, a predetermined amount of reinforcing agents such as carbon black, zinc white, stearic acid, sulfur, or various peroxides, and vulcanization accelerators are usually added. There is no problem in adding other additives such as inorganic fillers such as titanium white, talc, and calcium carbonate, anti-aging IL agents, and antistatic agents.

The amount of these additives added is
For 100 parts by weight, carbine black lθ~200 parts by weight, zinc white 1~1O parts by weight, stearic acid 0.1-1
0 parts by weight, 0.5 to 10 parts of sulfur, 1 to 10 parts of vulcanization aid
Parts by weight are preferred.

The vulcanized rubber composition of the present invention can be produced as follows. That is, predetermined amounts of the above-mentioned ethylene propylene rubber, modified rubber compound oil, carbon black, zinc white, and stearic acid are kneaded in a Banbury mixer at a temperature of 100 to 150°C for 9 hours for 1 to 10 minutes, and then Sulfur and a vulcanization accelerator may be added using an open roll.

[Examples of the Invention] Examples 1 to 3 (1) Production of modified rubber compound oil Diana Procell Oil PW380 (trade name, manufactured by Idemitsu Kosan 2) having the following properties was prepared as a paraffinic mineral oil.

That is, specific gravity (15/4 °C): 0.8789; flash point CaC: 300 °C; 4 parts Kinematic viscosity at °C and 100 °C = 381.8 cSt, 30.10 cSt
; Viscosity coefficient: 110; Pour point = -15.0°C; Refractive index (no): 1.4808; Sulfur content: 8 ppm;
72'J7 points: 144℃: Total acid value (mgKOH/g)
:0.01>;Ring analysis: C10%, CH77.0%
, Cp 73.0%:.

As polyethylene, Idemitsu polyethylene LO1148 and Idemitsu polyethylene 440M having properties shown in Table 2 were prepared.

A special grade reagent manufactured by Wako Tsumugi Pharmaceutical ■ was prepared as maleic anhydride.

As a radical generator, dicumyl peroxide (reagent grade) manufactured by Tokyo Kasei ■ was prepared.

First, Diana process oil PW380 and polyethylene were combined in the quantitative ratio shown in Table 3, placed in a stainless steel reaction vessel, and heated to 200°C to completely dissolve the polyethylene in the mineral oil. After cooling to 130° C., maleic anhydride and dicumyl peroxide were gradually added thereto and dissolved. Next, a radical polymerization reaction was carried out in a nitrogen stream at a temperature of 140°C for 5 hours. After the completion of the zero reaction, stripping treatment was carried out at 140°C for 2 hours at a pressure of 1*mHg to remove peroxide fragments and other peroxide particles. Various rubber compounding oils were prepared by removing the Ura-tenmono. Their properties are shown in Table 3.

For comparison, a sample containing no maleic anhydride was prepared and used as a comparative example. For reference, the properties of Diana Process Oil PW380 are also shown.

(2) Production of vulcanized rubber composition Next, ethylene propylene diene rubber EPT4095
(Product name, manufactured by Mitsui Petrochemical ■) 100 parts by weight.

140 parts by weight of carbon black (Asahi Carbon 80H, MAF, manufactured by Asahi Carbon ■), zinc white (No. 1, JISK14)
10-1982) 5 parts by weight, stearic acid (manufactured by Wako Tsumugi Pharmaceutical Co., Ltd., reagent special grade) 1'ffi parts, measuring section 6
The proportions of the above various rubber compounding oils shown in Table 4 in parts by weight (
1]! The whole mixture was put into a Banbury mixer and kneaded for 5 minutes at 120°C. The resulting kneaded product was transferred to a mixing roll with a surface temperature of 80°C, and 1 part of sulfur was added to it.
．． 511°C 1 part, 2-mercaptobenzothiazole 1f
fiffi part, tetramethylthiuram monosulfide 1.5i [(setting part) was added and passed through 8 times.Finally, it was placed in a mold and pressure-molded at 180°C for 15 minutes to produce a rubber specimen.

The hardness (Hs) and tensile stress at 100% strain of each specimen were measured according to the specifications below, and the results are shown in Table 4.

Hardness (Hs): Based on JIS-6301, type A test Tensile stress (kgf/c2): JIS-KE1
Compliant with 301 [Effects of the Invention] As is clear from the above explanation, the vulcanized rubber composition of the present invention has improved mechanical strength compared to conventional compositions, and is suitable for various rubber moldings, especially for automobiles. It has great industrial value as a material for rubber parts.

Procedural amendment May 15, 1981 Michibe Uga, Commissioner of the Patent Office1, Indication of the case, Patent Application No. 109421 filed in 19852, Name of the invention: Vulcanized rubber composition3, Person making the amendment Related Name of patent applicant Name of Toyoda Gosei Co., Ltd. Idemitsu Kosan Co., Ltd. 4, Agent 5, Date of amendment order Voluntary action 6, Subject of amendment Scope of claims and detailed explanation of the invention in the specification, Sections ■, Specification amend the claims as shown in the attached sheet.

II. In the Detailed Description of the Invention section of the specification, "Carbine Black" described on page 13, line 5 of the specification is replaced with "
Carbon black” is corrected.

Claims: Consisting of 100 parts by weight of ethylene propylene rubber, paraffinic mineral oil, polyethylene, and maleic anhydride, the amount of maleic anhydride added to the polyethylene is 0.5 to 2% by weight of the total, and , the absorbance at the 1-78c+s-' position in the infrared absorption spectrum and 840c+
A heated rubber compound characterized by being blended with 30 to 200 parts by weight of a modified rubber compounding oil whose ratio to the absorbance at the *-' position is within the range of 0.1 to 1.0.

Claims (1)

[Claims] It consists of paraffinic mineral oil, polyethylene, and maleic anhydride based on 100 parts by weight of ethylene propylene rubber, and the amount of maleic anhydride added to the polyethylene is 0.5 to 2% by weight of the total, and it is infrared resistant. Absorbance at 1778cm^-^1 position and 840cm in absorption spectrum
A vulcanized rubber compound comprising 30 to 200 parts by weight of a modified rubber compounding oil having a ratio to the absorbance at the ^-^1 position within the range of 0.1 to 1.0.