JPS62199634A - Oil-resistant, weather-resistant rubber composition - Google Patents

Abstract

PURPOSE:The titled rubber composition having improved mechanical strength and balanced oil resistance and free resistance, comprising nitrile rubber containing a specific functional group and olefinic rubber modified with a monomer containing a specific functional group as essential cmponents. CONSTITUTION:(A) Nitrile rubber (preferably containing hydroxyl group) comprising (i) 1-20wt% one or more monomers containing at least one group selected from epoxy group, carboxyl group, hydroxyl group, amino group and acid anhydride group, (ii) 15-50wt% alpha,beta-unsaturated nitrile and (iii) 30-80wt% conjugated diene is blended with (B) a modified olefinic rubber (preferably modified with maleic anhydride) obtained by adding 0.01-20pts.wt. one or more monomers containing epoxy group, carboxyl group, hydroxyl group, amino group or acid anhydride group to (i) 100pts.wt. ethylene-alpha-olefinic rubber in a weight ratio of the component A:B=95:5-5:95.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention provides an oil- and weather-resistant rubber that has excellent mechanical properties, an excellent balance between oil resistance and cold resistance, and has good ozone properties and bending resistance. Regarding the composition. For more details,
The present invention relates to a rubber composition containing as essential components a nitrile rubber having a functional group and an olefin rubber modified with a monomer having a functional group.

[Conventional technology]

Blending two or more types of elastomers has been practiced for a long time to bring out performance that cannot be obtained with a single elastomer. In addition to imparting new properties, blending techniques are also used to improve processability and reduce raw material costs. Typical examples include a blend composition of styrene-butadiene rubber (hereinafter referred to as SBR) and polybutadiene rubber (hereinafter referred to as BR) as a material for tire treads, and a blend composition of SBR and EPDM (hereinafter referred to as BR) as a material for tire sidewalls. -Propylene-
Examples include blend compositions of non-conjugated diene rubber). As seen in the latter example, the blend of FJPDM and other diene elastomers is intended to improve weather resistance, especially ozone resistance, but the mechanical properties of the blend are In general, it tended to decrease by blending. The partner to be blended with gPDM is acrylonitrile-butadiene rubber (hereinafter referred to as NB).
In the case of highly polar elastomers such as (abbreviated as R).

In particular, this tendency was remarkable, and blended materials could not be put to practical use due to their poor mechanical properties.

In order to improve these drawbacks of blending diene rubber and EPDM + R, T, Morr 1ssery
is 11! How to halogenate iPDM (Rubbe
r Chem.

Techno+, , 44.1025 (1971
), also RoPlMastro - mat tea
reported a method using a dialkyl dithiocarbamate salt or tetraalkylthiuram disulfide having a long-chain alkyl group as a vulcanization accelerator (Rubber Chem,
Techno+, 44.1065 (1971)
) is proposed.

Hashimoto et al. also reported a method in which EPDM is reacted with sulfur and a vulcanization accelerator to produce BPDM with pendant sulfur, and then blended with other rubber (Journal of the Japan Rubber Association, 49.236.
246 (1976)).

However, these solutions are quite effective when the diene rubber blended with EPDM is natural rubber/SBR, BR, which has low polarity, but when the blending partner is NBR, which is a highly polar elastomer. has little effect, and practical problems remain.

Furthermore, in order to improve the mechanical properties of a blend of Bl'DM and NBR, it has been proposed to combine di-IJ rubber having a functional group with halogenated EPDM.
This is proposed in Publication No. 38.

This effect is insufficient.

[Problem that the invention seeks to solve]

In recent years, due to improved performance, the demands on rubber materials, mainly for automotive applications, have become even more stringent.
There is a demand for a material having better mechanical strength than a blend of NBR and olefin rubber as a weather-resistant material.

[Means for solving problems]

As a result of intensive research in view of these points, the inventors of the present invention have introduced functional groups. It has been found that it is possible to produce a rubber composition that has mechanical strength and has an excellent balance of oil resistance, cold resistance, and weather resistance.

What is even more surprising is that in the blend of NBR and olefin rubber, the use of NBR partially introduced with functional groups and olefin rubber having functional groups that react with the NBR improves mechanical strength, oil resistance, and cold resistance. Improved balance.

We have also discovered that a material with excellent bending resistance can be obtained. Also, what have been studied as elastomer materials with excellent oil resistance and weather resistance?

EPD containing NBrL and a diene component as a crosslinking component
While it was a blend system of M, N
BR, and amine group, hydroxyl group.

In the case of a blend system of olefin rubber modified with a monomer having an epoxy group, carboxyl group, or acid anhydride group, olefin rubber (EPM) does not contain a diene component.
However, it was discovered that an oil- and weather-resistant material with an excellent balance of mechanical strength, oil resistance, and cold resistance can be obtained, and the present invention was achieved.

The present invention contains the following two l-IJ rubber (4) and olefin rubber (B), the mixing ratio of which is 95 by weight.
:5 to 5:95.

2) IJ rubber having at least one functional group selected from epoxy group, carboxyl group, hydroxyl group, amino group and acid anhydride group.

(B) A modified olefin rubber modified with at least one monomer selected from monomers having an epoxy group, a carboxyl group, a hydroxyl group, an amine group, or an acid anhydride group.

I will provide a.

The functional monomers used in the 2-IJ rubber according to the present invention are shown below.

Specifically, monomers containing carboxyl groups or acid anhydride groups include acrylic acid, methacrylic acid, maleic acid,
Maleic anhydride, fumaric acid.

Examples include α,β-unsaturated carboxylic acids such as itaconic acid and itaconic anhydride, and acid anhydrides thereof. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, allyl glycidyl ether, and vinyl glycidyl ether. As a hydroxyl group-containing monomer.

1-Hydroxypropyl (meth)acrylate.

2-Hydroxypropyl (meth)acrylate.

Examples include hydroxyethyl (meth)acrylate.

As the amine group-containing monomer, dimethylamine ethyl (
Examples include tertiary amino group-containing monomers such as meth)acrylate, diethylaminoethyl (meth)acrylate, and dibutylaminoethyl (meth)acrylate.

Polymerization to obtain the Nit-IJ rubber (T) is carried out by conventional emulsion polymerization, and is carried out at 0 to 50 DEG C. in a reactor from which oxygen is removed.

Monomers, emulsifiers, initiators, molecular weight regulators, and other polymerization agents may be added in their entirety before the start of the reaction, or may be added in arbitrary portions after the start of one reaction.

Further, operating conditions such as temperature and stirring can be arbitrarily changed during the reaction.

The polymerization method may be either a continuous method or a single batch method.

The molecular weight of the obtained polymer is not limited to %l, but the Mooney viscosity (ML = +41100°C) is preferably 20 to 120. If it is less than 20, rubber elasticity is poor, and if it exceeds 120, processability is poor.

The content of the functional group-containing monomer in the nitrile rubber (4) is preferably 1.0 to 20% by weight, more preferably 8 to 1% by weight.
It is 5% by weight.

If it is less than 1.0% by weight, the reactivity with the olefin rubber (B) will be poor and it will not be possible to obtain a material with good mechanical strength and an excellent balance between oil resistance and cold resistance, which are the effects of the present invention. If it exceeds 20% by weight, the elastic modulus increases significantly and rubber elasticity becomes poor.

The content of acrylonitrile monomer in the copolymer is 15-5
If it is less than 15% by weight, oil resistance will be poor. Moreover, if it exceeds 50% by weight, the properties as a rubber will be impaired.

As the olefin rubber 03), two or more monoolefins or at least one polyene that can be further copolymerized with them are copolymerized using a Ziegler-Natsuta catalyst represented by a combination of a vanadium compound and an aluminum compound. It can be obtained by using an essentially amorphous olefin rubber obtained by adding monomers having various functional groups thereto.

Examples of the amorphous olefin rubber include ethylene-α-olefin comb (EPM) and/or ethylene-α-olefin-diene monomer rubber (EPDM). Here, the α-olefin is 03 to C8 α-
Olefins, such as fluoropyrene, butenes 1. Examples include hexene-1°octene-1, but propylene is preferred.

Examples of the monomer having a functional group to be added to the olefin rubber (B) include monomers containing an amino group, a hydroxyl group, an epoxy group, a carboxyl group, or an acid anhydride group.

Specifically, diethylamine ethyl (meth)acrylate as a monomer containing an amino group.

Dimethylaminomethyl (meth)acrylate.

Examples include tertiary amino group-containing monomers such as vinylpyridine.

As a monomer containing a hydroxyl group.

Examples include hydroxypropyl (meth)acrylate and hydroxyethyl (meth)acrylate.

Examples of monomers containing epoxy groups include glycidyl (meth)acrylate, allyl glycidyl ether, and vinyl glycidyl ether.

Monomers containing carboxyl groups or acid anhydride groups include acrylic acid, methacrylic acid, ethacrylic acid,
maleic acid, maleic anhydride, fumaric acid, itaconic acid,
Itaconic anhydride.

Examples thereof include α/β-unsaturated carboxylic acids such as Himic acid and Himic acid anhydride, or acid anhydrides thereof.

Among these, monomeric compounds containing a carboxyl group or an acid anhydride group are preferred from the viewpoint of ease of carrying out the addition reaction operation to the olefin rubber.

Among these, maleic anhydride is particularly preferred.

The amount of monomers having these functional groups added to the olefin rubber is preferably 0.01 to 20 parts by weight, more preferably 0.2 to 5 parts by weight per 100 parts by weight of rubber.

If it is less than 0.01 part by weight, the effect of improving mechanical strength, which is the effect of the present invention, will not be sufficient, and if it exceeds 20 parts by weight, the physical properties of the rubber will tend to deteriorate due to gelation.

Regarding the addition reaction of monomers containing various functional groups to olefin rubber, methods such as those described in Japanese Patent Publication No. 39-6384 can be used. That is, the olefin rubber and various monomers can be mixed and heated in a solid state (preferably heated to 100 to 200°C) to cause the reaction to occur. The heating method may be either a closed kneader or a continuous heating reaction using an extruder or the like. At this time, one part of peroxide (preferably added in an amount of 0.1 to 910 parts per 100 parts of rubber) may be used to accelerate the reaction.

The combination of nitrile rubber (A) and olefin rubber (B) is not only simply mixed by blending, but also (
It also includes cases where component A) and component (B) partially react directly or via a filler.

The fact that nitrile rubber (A) and olefin rubber (B) react even in normal mixing methods such as Banbury kneading is due to the fact that EPM (containing 2, double bonds) is used as the base rubber of olefin rubber (B). This is clear from the fact that a high-strength composition can be obtained even when using (without).

More preferable effects of the present invention can be obtained when a hydroxyl group-containing rubber is used as the nitrile rubber (A) and a rubber modified with maleic anhydride as the olefin rubber (B) (!).

In the present invention, the mixing ratio of rubber (4) and rubber (B) is preferably such that the mixing weight ratio of component (4)/component (B) is in the range of 5/95 to 9515 from the viewpoint of improving mechanical strength.
More preferably, it is 10/90 to 90/10.

The effect of the present invention is that in addition to being used as a blend of component (4) and component (B), a part of the blend of general NBR and olefin rubber can be replaced with the combination system of component (g) and 103) according to the present invention. It can also be obtained by Namely, 1. It has been difficult to obtain a material with good mechanical strength from a blend of ordinary NBR and olefin rubber due to the difference in polarity. A part of this, preferably 2 or more of the total amount of rubber, is combined with component (A) according to the present invention [
By replacing it with a mixture of components F]), it is possible to improve the mechanical strength, and it is also possible to achieve a good balance between oil resistance and cold resistance.

The composition of the present invention includes component (4) which is an essential component;
ω) In addition to the unsaturated nitrile-conjugated diene rubber and olefin rubber, if necessary, ordinary rubber compounding agents such as carbon black, sulfur, plasticizer, process oil, and vulcanization accelerator are added, and the roll, Banbury, etc. This includes those kneaded using a conventional mixer such as a mixer, and vulcanized products thereof.

Regarding the physical properties of the composition of the present invention, mainly JIS K
-6301, the evaluation standards were a tensile test and a bending test for mechanical properties, an immersion test using JIS+8 oil for oil resistance, an ozone deterioration test for weather resistance, and a Gehman torsion test for cold resistance.

The present invention will be explained below using Examples.

The present invention is not limited to these in any way.

〔Example〕

The synthesis of nitrile rubber was carried out as follows.

Butadiene was polymerized at 30°C in an autoclave with an internal volume of 201 cm according to the polymerization recipe shown below.
55 Acrylonitrile
35 hydroxyethyl methacrylate
10 water 25
0 Sodium dodecylbenzenesulfonate 5 No. 8
Dodecyl mercaptan 0.5 Potassium persulfate 0.27 Cyanoethylated diethanolamine 0.15 Potassium hydroxide
0.10 per 100 parts of monomer after reaching 80 inches. Part Z of hydroxylamine sulfate was added to stop the polymerization. Subsequently, after heating and steam distillation to remove residual monomers, rubber solids content 10
Per 0 parts, 1 part of alkylated phenol was added as an anti-aging agent and coagulated with an aqueous calcium chloride solution, and the obtained crumbs were washed with water and vacuum dried at 50°C to prepare samples for evaluation. (Table 1 Samples) Copolymers prepared using the same formulations are summarized in Table 1 below.

In addition, when using a monomer having a carboxyl group,
When precipitating the copolymer, a portion of sulfuric acid was added to the calcium chloride aqueous solution.

The modified olefin rubber (B) was synthesized as follows.

Ethylene-propylene rubber (JSRg manufactured by Japan Synthetic Rubber Co., Ltd.)
P11 Mooney viscosity MI11+4 (100°C) = 40
) 1.2 parts of maleic anhydride and 0.6 parts of cumene hydroperoxide per 100 parts of
The mixture was transferred to a closed Banbury mixer preheated to 140°C and kneaded at 180°C for 5 minutes to obtain modified FJP(a).

In the same manner, acrylic acid and glycidyl methacrylate were used instead of maleic anhydride to produce modified EP (
b) and (C) were obtained.

For the modified EP (d), ethylene-propylene-diene rubber (JSREP-35 manufactured by Japan Synthetic Rubber Co., Ltd., uniform viscosity ML l+4 (100°C) = 83) was used.

This is a product obtained by modifying it with maleic anhydride.

The modified NBR and modified EP obtained according to the above method were kneaded in a Bamba IJ + mixer according to the formulation shown in the first table, and press vulcanized at 160° C. for 20 minutes.

Table 2 shows the results of evaluating the physical properties of the obtained vulcanizate.

Table 2 As is clear from the comparison between Example 1 and Comparative Examples 1 to 3 and Example 2 and Comparative Example 4, the composition of the present invention not only has good tensile strength but also oil resistance and cold resistance. It can be seen that it is an oil- and weather-resistant material with excellent balance of properties and good bending resistance.

Furthermore, as is clear from Examples 3 to 8, similar effects can be obtained by partially using the modified NBR/modified EP (DM) system.

〔Effect of the invention〕

The oil-resistant and weather-resistant material of the present invention has an excellent balance of mechanical strength, oil resistance, and cold resistance.

Hoses such as oil hoses, fuel hoses, gas hoses, and brake hoses, as well as hose cover materials, backings, gaskets, and O-rings.

Used for industrial parts such as belts, linings, oil seals, dust boots, etc., and parts for aircraft, automobiles, etc.

Furthermore, the rubber composition of the present invention contains both a highly polar rubber material called NBR and a low polarity rubber material called EP (DM), and can be used as a rubber for vulcanization adhesion between rubber materials with different polarities. is also suitable.

Claims (4)

[Claims] (1) Contains the following nitrile rubber (A) and olefin rubber (B), the mixing ratio of which is 95:5 to 95:5 by weight.
An oil-resistant and weather-resistant rubber composition having a ratio of 5:95. (A) epoxy group, carboxyl group, hydroxyl group,
A nitrile rubber having at least one functional group selected from an amino group and an acid anhydride group. (B) epoxy group, carboxyl group, hydroxyl group,
A modified olefin rubber modified with at least one monomer selected from monomers having an amino group or an acid anhydride group. (2) The nitrile rubber (A) contains at least one monomer selected from monomers having an epoxy group, a carboxyl group, a hydroxyl group, an amino group, or an acid anhydride group as a monomer unit constituting the polymer. mass 1.0 to 20% by weight, α,
The rubber composition according to claim 1, which is a nitrile rubber comprising 15 to 50% by weight of β-unsaturated nitrile and 30 to 80% by weight of conjugated diene. (3) The olefin rubber (B) is at least one monomer selected from monomers having an epoxy group, a carboxyl group, a hydroxyl group, an amino group, or an acid anhydride group, based on 100 parts by weight of the ethylene-α-olefin rubber. The rubber composition according to claims (1) to (2), which is an olefin rubber to which 0.01 to 20 parts by weight of one type of monomer is added. (4) The rubber composition according to claim (1), wherein the nitrile rubber (A) contains a hydroxyl group, and the olefin rubber (B) is modified with maleic anhydride. .