JP3060418B2 - Method for producing nitrile / urethane rubber molded article - Google Patents

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 nitrile / urethane rubber molded product, and more particularly, to oil resistance,
The present invention relates to a method for producing a nitrile / urethane-based rubber molded article having excellent chemical resistance and heat resistance, and also having excellent tensile strength and wear resistance.

[0002]

BACKGROUND OF THE INVENTION Nitrile rubber is excellent in oil resistance, chemical resistance and heat resistance, and its molded product is widely used as a sealing material such as packing and gasket, or as a diaphragm and a belt. Among the above properties, nitrile rubber is particularly excellent in oil resistance to fuel oil such as gasoline, light oil and the like, hydraulic oil, lubricating oil, and the like, and molded articles produced from this nitrile rubber are particularly preferable as automobile parts. Used.

In recent years, it has become necessary to use automobile parts and the like under more severe conditions, and accordingly, nitrile rubber has been required to have higher mechanical strength such as tensile strength and wear resistance. I have. In response to such demands, conventionally, in a nitrile rubber molded article, the mechanical strength has been improved by increasing the content of a structural unit derived from acrylonitrile or increasing the content of a filler.

[0004] However, a nitrile rubber molded article having a high content of constituent units derived from acrylonitrile,
Cold resistance tends to decrease, and when the content of the filler increases, the material becomes hard and rebound resilience (rubber elasticity) decreases.

For this reason, the mechanical strength such as tensile strength and abrasion resistance is improved while maintaining the excellent oil resistance, chemical resistance and heat resistance inherent in the nitrile rubber itself, which is excellent in rubber elasticity and cold resistance. There is a demand for the appearance of a rubber molded article obtained from such rubber.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and has excellent oil resistance, chemical resistance, and heat resistance, as well as mechanical strength such as tensile strength and wear resistance. An object of the present invention is to provide a method for producing an excellent nitrile / urethane rubber molded article.

[0007]

SUMMARY OF THE INVENTION A method for producing a nitrile / urethane rubber molded article according to the present invention comprises: [I] a nitrile rubber; 100 parts by weight, [II] (a) a polyol having two or more hydroxyl groups in a molecule, (b) a urethane rubber-forming material containing a polyisocyanate having two or more isocyanate groups in the molecule;
0 parts by weight of a nitrile / urethane rubber composition,
No vulcanizing agent added and no catalyst at 20-120 ° C
After kneading under heating at a temperature of 140 to 230 ° C. c
It is characterized by performing a rethanation reaction and vulcanizing.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, a method for producing a nitrile / urethane rubber molded article according to the present invention will be specifically described.

First, a nitrile / urethane rubber composition for forming a nitrile / urethane rubber molded article will be described. The nitrile / urethane rubber composition used in the present invention comprises: [I] a nitrile rubber; 100 parts by weight, and [II] a urethane rubber-forming material comprising (a) a polyol and (b) a polyisocyanate; And it consists of.

In the present invention, as such a nitrile rubber [I], those generally known as nitrile rubbers can be widely used. For example, an acrylonitrile / butadiene copolymer is preferably used.

Such an acrylonitrile / butadiene copolymer is represented by the following general formula. (—CH ₂ —CH ＝ CH—CH ₂ —) _x — (— CH ₂ —C (CN) H—) _Y Such an acrylonitrile / butadiene copolymer is
It can be manufactured by a conventionally known method.

Nitrile rubber [I] used in the present invention
Contains structural units derived from acrylonitrile in an amount of usually 15 to 51% by weight, preferably 20 to 45% by weight.

Next, the urethane rubber-forming material [II] will be described. In the present invention, the polyol (a) used as the urethane rubber-forming material [II] has two hydroxyl groups in the molecule.
Or more. Polyol used in the present invention,
It is preferably liquid. Usually, such (a) polyol preferably has a molecular weight of 500 to 5,000.

Specific examples of the polyol (a) include polyesters, polyethers, and polycarbonates. Examples thereof include the following compounds.

Polyoxypropylene glycol (PP
G) polyethers such as polyoxyethylene glycol (PEG) and polyoxytetramethylene glycol (PTMG).

Polyethylene adipate (PEA), polypropylene adipate (PPA), polytetramethylene adipate (PBA), polyhexamethylene adipate (PHA), ethylene adipate / diethylene adipate copolymer (PEDA), ethylene adipate / tetramethylene adipate Polymer (PBEA), ethylene adipate / propylene adipate copolymer (PEP
A) and polyesters such as poly-ε-caprolactone (PCL).

Polyhexamethylene carbonate (PH
C), polycyclohexane dimethylene carbonate (P
CC) and other polycarbonates.

Among these polyols, PTMG, P
EA, PPA, PEPA, PCL, PHC, PBEA and the like are preferably used. The polyisocyanate (b) used as the urethane rubber-forming material [II] has two or more isocyanate groups in the molecule.

Such polyisocyanates include:
Specifically, for example, the following compounds can be mentioned. MDI (4,4'-diphenylmethane diisocyanate),
TODI (trizine silisocyanate), 2,6-TDI
(Tolylene-2,6-diisocyanate), 2,4-TDI (tolylene-2,4-diisocyanate), NDI (naphthalene-
1,5-diisocyanate), PPDI (p-phenylene diisocyanate), TMDI (trimethylhexamethylene diisocyanate), IPDI (isophorone diisocyanate), HDI (hexamethylene diisocyanate), hydrogenated XDI (bis (isocyanatomethyl) cyclohexane), water MDI (dicyclohexylmethane diisocyanate LDI (lysine diisocyanate).

Of these, MDI, NDI, HDI,
TODI, TDI and PPDI are preferably used. The polyisocyanate as described above may be in the form of a powder or a liquid.

The urethane rubber-forming material [II] used in the present invention comprises the above-mentioned (a) polyol and (b) polyisocyanate. In such a urethane rubber-forming material [II], (a) the polyol and (b) the polyisocyanate are the equivalent ratio of the isocyanate group in the (b) polyisocyanate / active hydrogen in the (a) polyol (that is, N
(CO index) is preferably 1 to 10/1.

The urethane rubber-forming material [II] used in the present invention may contain, if necessary, a chain extender in addition to the above components. Such chain extenders include, for example, low molecular weight glycols whose both terminal groups are hydroxyl groups.

Specific examples include 1,4-butanediol, ethylene glycol, diethylene glycol, propylene glycol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4-cyclohexanedimethanol and the like.

The chain extender is a urethane rubber-forming material [II]
In the (b) isocyanate group in polyisocyanate /
(a) It is preferable that the polyol and the chain extender are blended so that the equivalent ratio of the total amount of active hydrogen in the chain extender (that is, the NCO index) is 1.0 to 5/1. Such a chain extender is contained in an amount of 0 to 100 parts by weight, preferably 0 to 70 parts by weight, when the total amount of (a) polyol and (b) polyisocyanate is 100 parts by weight.

The nitrile / urethane rubber composition used in the present invention comprises the above nitrile rubber [I] and the urethane rubber-forming material [II], and is obtained by kneading them, for example.

At the time of kneading, the urethane rubber-forming material [II] is used in an amount of 20 to 60 parts by weight, preferably 30 to 50 parts by weight, based on 100 parts by weight of the nitrile rubber [I] as described above.

The kneading is usually carried out under heating, and 50 to 1
At a temperature of 20C, preferably 70-90C, 10-9
It is performed for 0 minutes, preferably for 20 to 40 minutes. Such kneading can be performed using, for example, a kneader, a Banbury mixer, a roll mixer, or the like.

The nitrile / urethane rubber composition thus obtained contains the urethane rubber-forming material in the above-described amounts, thereby exhibiting the excellent oil resistance, chemical resistance and heat resistance inherent to nitrile rubber. While holding
A nitrile / urethane rubber molded article excellent in mechanical strength such as tensile strength and wear resistance can be formed.

In the present invention, a nitrile / urethane rubber composition obtained as described above is kneaded by adding a vulcanizing agent and then heated and vulcanized to produce a nitrile / urethane rubber molded article. .

Examples of the vulcanizing agent used in the present invention include sulfur and peroxide vulcanizing agents. Specific examples of the peroxide-based vulcanizing agent include 1,3-bis (tert-butylperoxyisopropyl) benzene, tert-butylhydroperoxide, and 1,4-bis (tert-butylperoxyisopropyl) benzene , 2,5-dimethylhexane-2,5
-Dihydroperoxide, dicumyl peroxide, 2,5-
Dimethyl-2,5-bis (tert-butylperoxy) hexane, tertbutylcumyl peroxide, 2,5-dimethyl-2,5
-tert-butylperoxyhexyne-3,1,1-bis (tert-
Butylperoxy) cyclododecane, 2,2-bis (tert-
Butylperoxy) octane, 1,1-bis (tert-butylperoxy) -3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate,
tert-butyl peroxybenzoate, tert-butyl peroxyisopropyl carbonate and the like.

Such a vulcanizing agent is usually used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of the nitrile / urethane rubber composition.
It is used in an amount of from 0.3 to 4 parts by weight, preferably from 0.3 to 4 parts by weight. At the time of kneading, the following rubber chemicals may be added together with the vulcanizing agent as long as the object of the present invention is not impaired.

As such rubber chemicals, vulcanization aids,
Fillers, reinforcing agents, plasticizers, processing aids, anti-aging agents and the like can be mentioned. Examples of the vulcanization aid include zinc oxide, guanidine compounds, sulfenamide compounds, thiuram compounds, dithiocarbamate compounds, aldehydeamine compounds, thiourea compounds, and xanthate compounds.

Such a vulcanization aid is usually used in an amount of 0.5 to 1 based on 100 parts by weight of the nitrile / urethane rubber composition.
It can be used in an amount of 0 parts by weight. Examples of the reinforcing agent and the filler include carbon black, silica, clay, silicate, alumina, aluminum hydroxide, calcium carbonate, and silicic acid.

The reinforcing agent and the filler are usually used in an amount of 5 to 150 parts by weight based on 100 parts by weight of the nitrile / urethane rubber composition.
It can be used in parts by weight. As a plasticizer, process oil, DOP (dioctyl phthalate), DOS
(Dioctyl sebacate), vegetable oil, factice, and the like.

Such a plasticizer can be used usually in an amount of 5 to 50 parts by weight based on 100 parts by weight of the nitrile / urethane rubber composition. Processing aids include stearic acid, polyethylene glycol, and the like.

The processing aid can be used usually in an amount of 0.5 to 3 parts by weight based on 100 parts by weight of the nitrile / urethane rubber composition. As an anti-aging agent, 2,6-di-t
ert-butyl-4-methylphenol, N-isopropyl-N'-
Examples include phenyl-p-phenylenediamine, poly (2,2,4-trimethyl-1,2-dihydroquinoline), and special waxes.

The antioxidant can be used usually in an amount of 0.5 to 3 parts by weight based on 100 parts by weight of the nitrile / urethane rubber composition. The rubber chemicals as described above may be added to the nitrile / urethane rubber composition before kneading by adding a vulcanizing agent, or by adding a vulcanizing agent to the nitrile / urethane rubber composition. It may be added after kneading. In the latter case, it is preferable to add a rubber chemical to the kneaded product of the nitrile / urethane rubber composition and the vulcanizing agent and further knead the mixture. In the present invention, the nitrile rubber [I], the urethane rubber-forming material [II], the vulcanizing agent and, if necessary, the rubber chemicals may be simultaneously kneaded.

The kneading can be carried out using a kneader, a Banbury mixer, a roll mixer or the like as described above. Such kneading is carried out at 20 to 120 ° C, preferably 5 to 120 ° C.
At a temperature of 0 to 80 ° C, 5 to 30 minutes, preferably 10 to
It takes 20 minutes.

Next, the kneaded material obtained as described above is heated and vulcanized and molded to obtain a nitrile / urethane rubber molded body. In the vulcanization molding, specifically, the kneaded material is filled in a mold having a desired shape, and heated at 140 to 230 ° C, preferably 150 to 180 ° C for 3 to 60 minutes, preferably 10 to 30 minutes. Done.

In general, even when nitrile rubber and urethane rubber are mixed, both are high in viscosity and low in fluidity, so they are only physically mixed, and a network (entanglement) at a molecular level is obtained. Is not formed. Therefore,
A molded article obtained by simply vulcanizing a nitrile rubber mixed with a urethane rubber does not have improved mechanical strength as compared with a nitrile rubber molded article.

On the other hand, in the present invention, a vulcanizing agent is added to a nitrile / urethane rubber composition composed of a nitrile rubber and a urethane rubber-forming material, and the mixture is kneaded and then vulcanized, so that oil resistance, A rubber molded article having excellent chemical resistance and excellent mechanical strength such as tensile strength and wear resistance can be obtained. This is presumed to be due to the following reasons.

That is, the urethane rubber-forming material [II] used in the present invention comprises the above-mentioned (a) polyol and (b)
It consists of polyisocyanate and is uniformly dispersed in the nitrile rubber by kneading with the nitrile rubber [I].
By heating and vulcanizing a rubber composition comprising such a urethane rubber-forming material [II] and a nitrile rubber [I],
It is considered that the urethane rubber-forming material reacts and polymerizes, and also reacts with the nitrile rubber to form a network at the molecular level between the nitrile molecular chains and the urethane molecular chains.

The nitrile / urethane rubber molded article according to the present invention obtained as described above retains the excellent oil resistance, chemical resistance and heat resistance inherent to the nitrile rubber itself, while maintaining the tensile strength and wear resistance. Also has excellent mechanical strength.

[0044]

According to the present invention, a nitrile / urethane having improved mechanical strengths such as tensile strength and abrasion resistance while maintaining the excellent oil resistance, chemical resistance and heat resistance inherent of the nitrile rubber itself. A rubber molded body can be manufactured.

Hereinafter, the present invention will be described with reference to Examples.
The present invention is not limited to these examples.

[0046]

Example 1 and 2
C., and the rolls were filled with the components shown in Table 1 below and kneaded at 80.degree. C. for 60 minutes.

The kneaded product obtained in this manner is
It was vulcanized by heating to ° C. Table 1 shows the physical properties of the obtained molded body.

[0048]

Comparative Example 1 Nitrile rubber was used as a component shown in Table 1.
The mixture was heated to 160 ° C. and vulcanized to obtain a molded product.

Table 1 shows the physical properties of the obtained molded body.

[0050]

Comparative Example 2 Nitrile rubber and urethane rubber were mixed at 70 ° C. for 30 minutes with the components shown in Table 1.

The mixture obtained in this way is
The mixture was heated to ℃ and vulcanized to obtain a molded product. Table 1 shows the physical properties of the obtained molded body.

[0052]

[Table 1]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI C08L 75:04) 33:20 (58) Investigated field (Int.Cl. ⁷ , DB name) C08L 33/20 C08L 9/02 C08L 75/04

Claims (2)

(57) [Claims] (I) a nitrile rubber; 100 parts by weight, (II) (a) a polyol having two or more hydroxyl groups in a molecule, and (b) a polyisocyanate having two or more isocyanate groups in a molecule. Urethane rubber-forming material containing: 20-6
0 parts by weight of a nitrile / urethane rubber composition,
No vulcanizing agent added and no catalyst at 20-120 ° C
After kneading under heating at a temperature of 140 to 230 ° C. c
A method for producing a nitrile / urethane rubber molded article, comprising performing a rethanation reaction and vulcanizing. 2. The method for producing a nitrile / urethane rubber molded article according to claim 1, wherein (a) the polyol is in a liquid state.