JPH07268004A - Production of modified hydrogenated nitrile rubber - Google Patents

Abstract

PURPOSE:To produce a highly saturated nitrile rubber improved in strength at ordinary and high temperatures and reduced in elongation stress at high temperature. CONSTITUTION:A highly saturated nitrile polymer rubber having an iodine value of at most 80 is subjected to an addition reaction with maleic anhydride or its derivative in an amount, in terms of the acid eqqivalents thereof, of at least 5X10<-3>ephr. The use of the rubber thereby produced can give a rubber composition excellent in strength characteristics while retaining the performance highly balanced among oil resistance, heat resistance, weatheratility and low- temperature resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a novel modified hydrogenated nitrile rubber, and in particular, it maintains the performance in which oil resistance, heat resistance, weather resistance and cold resistance are highly balanced, and The present invention relates to a method for producing a modified hydrogenated nitrile rubber capable of obtaining an excellent rubber composition.

[0002]

2. Description of the Related Art A hydrogenated acrylonitrile-butadiene copolymer rubber (NBR) is known as an excellent rubber having a balance of oil resistance, heat resistance, weather resistance, cold resistance and strength. Since hydrogenated NBR has such excellent properties, it is used in applications requiring oil resistance, heat resistance and strength such as a toothed conductive belt (timing belt) for automobiles.

However, even in such an application, from the viewpoint of long-term use, a high level of strength at room temperature and high temperature is required, and power transmission is further ensured, which is a drawback of hydrogenated NBR. Improvements have been sought for the low low tensile stress (eg, 50% tensile stress) at some elevated temperatures.

On the other hand, it is known that the strength of NBR is improved by further copolymerizing a carboxyl group-containing monomer. However, the hydride of NBR obtained by copolymerizing a carboxyl group-containing monomer is also excellent in the strength at normal temperature and high temperature, but the low elongation stress at high temperature is due to hydrogenated N
It is not much different from BR and is not improved.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a highly saturated nitrile group-containing rubber which has improved strength at room temperature and high temperature as well as low tensile stress at high temperature. As a result of intensive research, the present inventors have found that the above object can be achieved by using a modified hydrogenated nitrile rubber produced by adding maleic anhydride or the like to a highly saturated nitrile group-containing rubber and completed the present invention. Came to do.

[0006]

Thus, according to the present invention, maleic anhydride or a derivative thereof is added to a nitrile group-containing highly saturated polymer rubber having an iodine value of 80 or less at an acid equivalent of 5 × 10 5 of maleic anhydride or a derivative thereof. Provided is a method for producing a modified hydrogenated nitrile rubber, which comprises adding ^-3 ephr or more.

As the nitrile group-containing highly saturated polymer rubber used in the present invention, unsaturated nitrile-conjugated diene copolymer rubber obtained by hydrogenating the conjugated diene unit portion, unsaturated nitrile-conjugated diene-ethylenically unsaturated monomer Examples thereof include a ternary copolymer rubber, a rubber obtained by hydrogenating a conjugated diene unit portion of the rubber, and an unsaturated nitrile-ethylenically unsaturated monomer copolymer rubber. These nitrile group-containing highly saturated polymer rubbers can be obtained by using a usual polymerization method and a usual hydrogenation method, but it goes without saying that the method for producing the rubber is not particularly limited in the present invention.

The monomers used for producing the above-mentioned nitrile group-containing highly saturated polymer rubber are exemplified below.
Acrylonitrile, methacrylonitrile and the like are used as unsaturated nitriles, and 1,3-butadiene, 2,3-dimethylbutadiene, isoprene and 1,3 are used as conjugated dienes.
-Pentadiene and the like. Examples of the ethylenically unsaturated monomer include vinyl aromatic compounds such as styrene, chlorostyrene, Pt-butylstyrene and chloromethylstyrene, esters of unsaturated carboxylic acids such as methyl acrylate and 2-ethylhexyl acrylate, methoxymethyl acrylate, Alkoxyalkyl esters of unsaturated carboxylic acids such as ethoxyethyl acrylate and methoxyethoxyethyl acrylate, unsaturated carboxylic acid amides such as acrylamide and methacrylamide, N-methylol (meth) acrylamide,
N, N'-dimethylol (meth) acrylamide, N-
N-substituted (meth) acrylamides such as ethoxymethyl (meth) acrylamide are included.

In the unsaturated nitrile-ethylenically unsaturated monomer copolymer rubber, a part of the unsaturated monomer is a non-conjugated diene such as vinyl norbornene, dicyclopentadiene or 1,4-hexadiene. It may be substituted and copolymerized.

As the nitrile group-containing highly saturated polymer rubber used in the present invention, specifically, butadiene-acrylonitrile copolymer rubber, isoprene-butadiene-acrylonitrile copolymer rubber, isoprene-acrylonitrile copolymer rubber, etc. are hydrogenated. Butadiene-methyl acrylate-acrylonitrile copolymer rubber, butadiene-styrene-acrylonitrile copolymer rubber, and hydrogenated products thereof, butadiene-ethylene-acrylonitrile copolymer rubber, butyl acrylate-ethoxyethyl acrylate-vinyl chloroacetate-acrylonitrile Examples thereof include copolymer rubber, butyl acrylate-ethoxyethyl acrylate-vinyl norbornene-acrylonitrile copolymer rubber, and the like.

It is necessary to select and use one having an iodine value of 80 or less among these polymer rubbers, and this iodine value is determined according to JIS K 0070.

Maleic anhydride and its derivatives used in the present invention include maleic anhydride, maleic acid, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid monobutyl ester, maleic acid mono-2-ethylhexyl ester and the like. Acid monoalkyl ester, maleimide, N-methylmaleimide,
Maleimides such as N-ethylmaleimide and N-phenylmaleimide are included.

In the present invention, maleic anhydride or a derivative thereof is added to a nitrile group-containing highly saturated polymer rubber to produce a modified hydrogenated nitrile rubber. The ene addition method or the radical addition method in the presence of a radical generator is used. The ene addition method and radical addition method include heating a nitrile group-containing highly saturated rubber and maleic anhydride or a derivative thereof in an inert solvent in which they are dissolved, or heating a mixture of the polymer rubber and maleic anhydride. Is a method of causing an addition reaction with maleic anhydride or a derivative thereof. The addition reaction can be carried out, for example, in the case of a solution in a chemical reaction container such as an autoclave, and the reaction in the solid phase can be carried out by a mixing processor such as a closed kneader or a kneading extruder.

In the case of the present invention, the addition amount of maleic anhydride or its derivative is not particularly limited, but preferably the acid equivalent (ephr, rubber) of maleic anhydride or its derivative with respect to the nitrile group-containing highly saturated polymer rubber. It is 5 × 10 ⁻³ ephr or more in g equivalent per 100 g).

The modified hydrogenated nitrile rubber obtained in the present invention contains a metal oxide of Group 2 of the periodic table, a vulcanizing agent, an antioxidant,
By adding a filler and the like, it is possible to obtain a vulcanizable rubber composition with high stress and high strength, which has an excellent performance balance of oil resistance, heat resistance, weather resistance, and cold resistance.

Among these compounding agents, examples of the metal oxide of Group 2 of the periodic table include magnesium oxide, zinc oxide, calcium oxide, strontium oxide and the like. Zinc oxide and magnesium oxide are particularly preferable. The amount of the metal oxide used is usually 0.5 to 30 parts by weight (hereinafter the same) per 100 parts by weight of the rubber.

As the vulcanizing agent, sulfur and / or a sulfur donating compound (hereinafter sometimes referred to as sulfur-based vulcanizing agent)
And organic peroxides. When a sulfur-based vulcanizing agent is used, stearic acid and various vulcanization accelerators are usually used together.

Examples of the sulfur-donating compound include thiuram compounds such as tetramethylthiuram disulfide and tetraethylthiuram disulfide, and morpholine compounds such as morpholine disulfide. The amount of sulfur or sulfur donating compound used is usually 0.1 to 5 parts by weight. The vulcanization accelerator used in combination with these is a thiazole compound such as 2-mercaptobenzothiazole or 2-mercaptothiazoline, or a sulfenamide such as N-cyclohexyl-2-benzothiazyl-sulfenamide from the viewpoint of heat resistance and strength. Although it is preferable to use a system compound or the like, a vulcanization accelerator other than these may be used. The amount of the vulcanization accelerator used is usually in the range of 0.5 to 5 parts by weight.

Examples of the organic peroxide which is a vulcanizing agent include dicumyl peroxide, benzoyl peroxide, 2,
4-dichlorodibenzoyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxybenzoate and the like can be mentioned.

The amount used is usually 0.5 to 15 parts by weight, preferably 4 to 10 parts by weight. When using an organic peroxide as a vulcanizing agent, a polyfunctional compound such as triallyl cyanurate, triallyl isocyanurate, trimethylolpropane trimethacrylate, ethylene dimethacrylate, divinylbenzene, diallyl phthalate, toluylene bismaleimide, etc. A monomer or the like can be used together as a vulcanization aid. The amount used is usually 1 to 10 parts by weight. In addition, heat resistance can be improved by using a polyhydric alcohol together. Examples of the polyhydric alcohol include polyethylene glycol, polypropylene glycol, ethylene glycol and propylene glycol, and the amount used is preferably in the range of 0.5 to 10 parts by weight.

As the antiaging agent, when a sulfur-based vulcanizing agent is used, it is desirable to use an antiozonant. Antiozonants include N-phenyl-N'-isopropyl-p-phenylenediamine, N-cyclohexyl-
N'-phenyl-p-phenylenediamine, N- (1,
3-dimethylbutyl) -N'-phenyl-p-phenylenediamine, N, N'-di (1-ethyl-3-methylbenzyl) -p-phenylenediamine and the like can be mentioned.
The amount of these used is usually in the range of 0.1 to 5 parts by weight.
When the vulcanizing agent is an organic peroxide, the antiozonant may not be used.

From the viewpoint of heat resistance, it is desirable to use an oxidative deterioration inhibitor. When a sulfur-based vulcanizing agent is used, alkylated diphenylamine such as octylated diphenylamine, 4,4′-bis (α, α-dimethylbenzyl)
Examples thereof include amine compounds such as diphenylamine, mercaptobenzimidazole compounds such as 2-mercapto-benzimidazole and zinc or nickel salts of 2-mercaptobenzimidazole. The amount used is 0.1
The range of 5 parts by weight is preferred.

When an organic peroxide is used as the vulcanizing agent, 6-ethoxy-2,2,4-trimethyl-1,2 is used.
-Dihydroquinoline, 2,2,4-trimethyl-1,2
-Polymer of dihydroquinoline, 6-dodecyl-2,2,
Examples thereof include quinoline-based antioxidants such as 4-trimethyl-1,2-dihydroquinoline, and mercaptobenzimidazole-based antioxidants such as 2-mercaptobenzimidazole and zinc or nickel salts of 2-mercaptobenzimidazole. The amount used is preferably in the range of 0.1 to 5 parts by weight.

The filler which can be used in the modified hydrogenated nitrile rubber obtained in the present invention includes various inorganic fillers generally used in the rubber industry such as carbon black, silica, calcium carbonate and clay. The amount used is usually 10 to 200 parts by weight. Further, the filler is not limited to the inorganic filler, and organic fillers such as phenol resin, xylene resin and melamine resin, and various monofilaments such as glass monofilament and aramid monofilament (pulp) can be used.

The vulcanizable rubber composition is prepared by rolling the modified hydrogenated nitrile rubber obtained in the present invention and the above-mentioned various compounding agents into a roll,
It is produced by mixing using a conventional mixer such as Banbury. At that time, a compounding agent other than the above, for example, a plasticizer, a process oil, a processing aid, a pigment, a vulcanization retarder and the like can be added and mixed if necessary.

The obtained rubber composition may be used as it is, or may be a polyester woven fabric, a nylon woven fabric, cord-shaped fibers,
For example, after being compounded with polyester fiber, glass fiber, aramid fiber, carbon fiber, steel fiber, etc., a desired rubber product is obtained through a vulcanization process.

The vulcanizate obtained from the vulcanizable rubber composition using the modified hydrogenated nitrile rubber obtained in the present invention shows excellent oil resistance, heat resistance, weather resistance and cold resistance, and is markedly improved. Belts that have constant stress strength and dynamic fatigue resistance and are constantly subjected to repeated deformation, especially V-belts, poly-V-belts and toothed conductive belts used for automobiles;
Power steering hoses for automobiles, high pressure oil resistant hoses such as hydraulic hoses for various machines such as construction machinery, hoses such as fuel hoses for automobiles; various rubber products used in oil wells and gas wells, such as packers and blowout preventers (Blowout) Preventer), pipe protector, etc .; O
-Various sealing materials such as rings, gaskets, oil seals and freon seals; various diaphragms; friction plates such as automobile clutch plates and brake shoes; and other various products.

The vulcanizable rubber composition is a thermoplastic resin such as polyamide resin, polyester resin, polyimide resin, polyacetal resin, polycarbonate resin, polyvinylidene fluoride resin, tetrafluoroethylene-ethylene copolymer resin, and the like. It can also be used by blending it with a thermosetting resin such as urethane resin, epoxy resin, phenol resin, urea / melamine resin.

[0029]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The parts and% in the examples, comparative examples and reference examples are based on weight unless otherwise specified.

Production Example Hydrogenated nitrile rubber in an autoclave (Zeon Pol 2020 manufactured by Zeon Corporation, Mooney viscosity 82, nitrile content 3
7.6%, iodine value 28.2) was dissolved in methyl ethyl ketone and maleic anhydride (No. 1-4 in Table 1) or maleic acid (No. 5-6 in Table 1) was added and then an inert gas was added. The reaction was carried out at 95 ° C. for 4 hours while continuously adding a methyl ethyl ketone solution of benzoyl peroxide under an atmosphere. In Nos. 1 to 4 of Table 1, the reaction product was n-hexane /
Diethyl ether mixed solvent, No. 5-6 in Table 1
Then, reprecipitation with methanol was repeated 5 times for purification,
After confirming by gas chromatography that no unreacted maleic anhydride or maleic acid remained in the produced rubber, it was dried to obtain a modified rubber for evaluation test. Table 1
It was confirmed by infrared absorption spectra that the modified rubbers Nos. 1 to 4 shown in Table 1 were added to the modified rubber as succinic anhydride groups, and the modified rubbers Nos. 5 to 6 were added as succinic acid groups to the modified rubber.

The trial-modified rubber, the above-mentioned hydrogenated nitrile rubber, carboxylated nitrile rubber (Nippon 1072J manufactured by Zeon Corporation), and acrylonitrile, methacrylic acid and butadiene are copolymerized and then hydrogenated by a conventional method. The properties of the nitrile rubber (prototype) are shown in Table 1. In each case, the gel content (methyl ethyl ketone insoluble matter that did not pass through the 80 mesh wire mesh) was 0.

[0032]

[Table 1]

Test Example Various rubbers shown in Table 1 were mixed with various compounding agents according to the compounding recipe shown in Table 2 on a cooling roll to obtain a rubber compound.
These were press-vulcanized at 160 ° C. for 30 minutes and then further heat-treated as secondary vulcanization in a heating oven at 150 ° C. for 2 hours under atmospheric pressure to obtain a vulcanized product. Physical property evaluation is JIS K 6301
It carried out according to. The tensile test was carried out in an atmosphere of 23, 100, 125 and 150 ° C. using a tensile tester with a constant temperature bath. Cold resistance was measured with a Gehmann low temperature torsion tester. Oil resistance is 2 at 120 ° C with JIS # 3 oil.
The volume change rate after immersion for 70 hours was measured. The dynamic viscoelasticity was measured with a viscoelasticity spectrometer (Kishimoto Seisakusho) at a frequency of 50 Hz, initial strain of 15%, dynamic strain of 0.2%,
The measurement temperature range was -50 to 150 ° C. The results are shown in Table 2. The temperature dependence of the 50% tensile stress (M ₅₀ ) in the table is shown in FIG. 1 as a graph.

[0034]

[Table 2]

From the results of Table 2 and FIG. 1, the modified hydrogenated nitrile rubber to which maleic anhydride or maleic acid has been added is suppressed in increase in hardness as compared with hydrogenated nitrile rubber and carboxylated hydrogenated nitrile rubber. High stress, high strength, high stress at high temperature and almost no change in hot stress, almost no change in hardness at high temperature, ionic bond such as carboxylated hydrogenated nitrile rubber or Tan δ by cluster
It can be seen that there is no peak occurrence, that it has excellent cold resistance, and that it has excellent oil resistance. As described above, the modified hydrogenated nitrile rubber to which maleic anhydride or maleic acid is added is completely different from the carboxylated hydrogenated nitrile rubber obtained by copolymerizing (meth) acrylic acid even with the same carboxylic acid. I understand.

[0036]

The vulcanizable rubber composition using the modified hydrogenated nitrile rubber obtained according to the present invention has excellent properties which have not been obtained in the past, and is useful for expanding the application of rubber. .

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between 50% tensile stress and temperature measured for rubber vulcanizates.

[Table 2]

[Table 2]

[Table 2]

Claims (1)

[Claims] 1. A nitrile group-containing highly saturated polymer rubber having an iodine value of 80 or less and maleic anhydride or a derivative thereof in an acid equivalent of 5 × 10 ^{−3 of} maleic anhydride or a derivative thereof.
A method for producing a modified hydrogenated nitrile rubber, characterized by adding ephr or more.