JPH04296345A - Production of nitrile/urethane rubber molded article - Google Patents

Abstract

PURPOSE:To provide a process for producing a nitrile-urethane rubber molded article having excellent oil-resistance, chemical resistance and heat-resistance as well as excellent mechanical strength such as tensile strength and abrasion resistance. CONSTITUTION:The objective article can be produced by adding a vulcanizing agent to a nitrile/urethane rubber composition composed of [I] 100 pts.wt. of a nitrile rubber and [II] 20-60 pts.wt. of a material for forming a nitrile/urethane rubber and containing (a) a polyol having >=2 hydroxyl groups in the molecule and (b) a polyisocyanate having >=2 isocyanate groups in the molecule, kneading the mixture and forming and vulcanizing the kneaded product.

Description

[Detailed description of the invention]

0001

TECHNICAL FIELD OF THE INVENTION The present invention relates to a method for producing a nitrile/urethane rubber molded article, and more particularly, to
The present invention relates to a method for producing a nitrile/urethane rubber molded product that has excellent chemical resistance and heat resistance, as well as tensile strength and abrasion resistance.

0002

Technical Background of the Invention Nitrile rubber has excellent oil resistance, chemical resistance, and heat resistance, and its molded products can be used as sealing materials such as packings and gaskets, or as diaphragms, etc.
Widely used as belts, etc. Among the above-mentioned properties, nitrile rubber has particularly excellent oil resistance against fuel oils such as gasoline and diesel oil, as well as hydraulic oils and lubricating oils, and molded objects manufactured from this nitrile rubber are particularly preferred as automobile parts. It is used.

[0003]In recent years, it has become necessary to use automobile parts under even more severe conditions, and with this, nitrile rubber is also required to have even greater mechanical strength such as tensile strength and abrasion resistance. There is. In response to such demands, mechanical strength has conventionally been improved in nitrile rubber molded articles by increasing the content of structural units derived from acrylonitrile or by increasing the content of fillers.

[0004] However, nitrile rubber molded articles with a high content of structural units derived from acrylonitrile,
Cold resistance tends to decrease, and when the filler content increases, it becomes hard and impact resilience (rubber elasticity) decreases.

[0005] For this reason, it has excellent rubber elasticity and cold resistance, and also has improved mechanical strength such as tensile strength and abrasion resistance while maintaining the excellent oil resistance, chemical resistance, and heat resistance that nitrile rubber itself inherently has. It is desired that a rubber molded article obtained from rubber is produced.

[0006]

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

[0007]

Summary of the Invention The method for producing a nitrile/urethane rubber molded article according to the present invention comprises: [I] nitrile rubber; 100 parts by weight; [II] (a)
A polyol having two or more hydroxyl groups in the molecule, and (b
) A urethane rubber forming material containing a polyisocyanate having two or more isocyanate groups in the molecule; 20-6
A nitrile/urethane rubber composition consisting of 0 parts by weight,
It is characterized by adding a vulcanizing agent and kneading it, followed by heating and vulcanization molding.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The method for producing a nitrile/urethane rubber molded article according to the present invention will be explained in detail below.

First, a nitrile/urethane rubber composition for forming a nitrile/urethane rubber molded article will be explained. The nitrile/urethane rubber composition used in the present invention includes [I] nitrile rubber; 100 parts by weight, and [II] (a)
A urethane rubber forming material consisting of a polyol and (b) a polyisocyanate; 20 to 60 parts by weight.

In the present invention, such nitrile rubber [I
] As the nitrile rubber, a wide variety of nitrile rubbers can be used, and for example, acrylonitrile/butadiene copolymer is preferably used.

Such an acrylonitrile/butadiene copolymer is represented by the following general formula. (-CH2-CH=CH-CH2-)x-(-CH
2-C(CN)H-)Y Such an acrylonitrile/butadiene copolymer can be produced by a conventionally known method.

The nitrile rubber [I] used in the present invention usually contains structural units derived from acrylonitrile.
It is contained in an amount of 15 to 51% by weight, preferably 20 to 45% by weight.

Next, the urethane rubber forming material [II] will be explained. In the present invention, the urethane rubber forming material [II
] The polyol (a) used as the polyol has two or more hydroxyl groups in the molecule. The polyol used in the present invention is preferably liquid. Like this (a)
It is generally preferred that the polyol has a molecular weight of 500 to 5,000.

Specific examples of such (a) polyols include polyesters, polyethers, and polycarbonates, including the following compounds.

Polyoxypropylene glycol (PPG)
), 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 copolymer Polymer (PBEA), ethylene adipate/propylene adipate copolymer (PEPA)
, polyesters such as poly-ε-caprolactone (PCL).

Polyhexamethylene carbonate (PHC)
), polycyclohexane dimethylene carbonate (PC
C) and other polycarbonates.

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

[0019] As such polyisocyanate,
Specifically, the following compounds can be mentioned, for example. MDI (4,4'-diphenylmethane diisocyanate), TODI (tolidine silyisocyanate), 2,
6-TDI (tolylene-2,6-diisocyanate),
2,4-TDI (tolylene-2,4-diisocyanate), NDI (naphthalene-1,5-diisocyanate)
, PPDI (p-phenylene diisocyanate), TM
DI (trimethylhexamethylene diisocyanate),
IPDI (isophorone diisocyanate), HDI (hexamethylene diisocyanate), hydrogenated XDI (bis(
isocyanatomethyl)cyclohexane), hydrogenated MDI (
Dicyclohexylmethane diisocyanate LDI (lysine diisocyanate).

Among these, MDI, NDI, HDI,
TODI, TDI, and PPDI are preferably used. The above polyisocyanate may be in powder form or liquid form.

The urethane rubber forming material [II] used in the present invention comprises (a) a polyol as described above and (b)
Consists of polyisocyanate. In such a urethane rubber forming material [II], (a) a polyol and (
b) A polyisocyanate is one in which the equivalent ratio of (b) isocyanate groups in the polyisocyanate/(a) active hydrogen in the polyol (i.e., NCO index) is 1 to
Preferably, the ratio is 10/1.

[0022] The urethane rubber forming material [II] used in the present invention may contain a chain extender, if necessary, in addition to the above-mentioned components. Examples of such chain extenders include low molecular weight glycols in which both terminal groups are hydroxyl groups.

Specifically, 1,4-butanediol, ethylene glycol, diethylene glycol, propylene glycol, 1,4-bis(β-hydroxyethoxy)
Examples include benzene and 1,4-cyclohexanedimethanol.

The chain extender is the urethane rubber forming material [II
], the equivalent ratio of (b) isocyanate groups in the polyisocyanate/(a) total amount of active hydrogen in the polyol and chain extender (i.e., NCO index) is 1.0 to
It is preferable that the ratio is 5/1. Such a chain extender is 0 to 1 part by weight when the total amount of (a) polyol and (b) polyisocyanate is 100 parts by weight.
00 parts by weight, preferably 0 to 70 parts by weight.

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

During kneading, 20 to 60 parts by weight, preferably 30 to 50 parts by weight of the urethane rubber forming material [II] are added to 100 parts by weight of the above-mentioned nitrile rubber [I].
Used in parts by weight.

[0027] Kneading is usually carried out under heating, and
At a temperature of 20°C, preferably 70-90°C, 10-9
0 minutes, preferably 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 has the excellent oil resistance, chemical resistance, and heat resistance inherent in nitrile rubber by containing the urethane rubber forming material in the above amount. While holding
It is possible to form a nitrile/urethane rubber molded article with excellent mechanical strength such as tensile strength and abrasion resistance.

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

[0030] Examples of the vulcanizing agent used in the present invention include sulfur and peroxide-based vulcanizing agents. Specifically, peroxide-based vulcanizing agents include 1,3-bis(ter)
tert-butylperoxyisopropyl)benzene, ter
t-Butyl hydroperoxide, 1,4-bis(ter)
t-butylperoxyisopropyl)benzene, 2,
5-dimethylhexane-2,5-dihydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-
Bis(tert-butylperoxy)hexane, t
ertbutylcumyl peroxide, 2,5-dimethyl-
2,5-tert-butylperoxyhexine-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-butylperoxybenzoate, te
Examples include rt-butylperoxyisopropyl carbonate.

Such a vulcanizing agent is usually used in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the nitrile/urethane rubber composition.
It is used in an amount of 0.3 to 4 parts by weight, preferably 0.3 to 4 parts by weight. During kneading, the following rubber chemicals may be added together with the vulcanizing agent to the extent that the object of the present invention is not impaired.

[0032] Such rubber chemicals include vulcanization aids,
Fillers, reinforcing agents, plasticizers, processing aids, anti-aging agents, etc. may be mentioned. Examples of the vulcanization aid include zinc oxide, guanidine compounds, sulfenamide compounds, thiuram compounds, dithiocarbamate compounds, aldehyde amine compounds, thiourea compounds, and xanthate compounds.

[0033] Such a vulcanization aid is usually used in an amount of 0.5 to 1 part by weight per 100 parts by weight of the nitrile/urethane rubber composition.
It can be used in an amount of 0 parts by weight. Reinforcing agents and fillers may include carbon black, silica, clay, silicates, alumina, aluminum hydroxide, calcium carbonate, silicic acid, and the like.

[0034] The reinforcing agent and filler are usually used in an amount of 5 to 150 parts by weight per 100 parts by weight of the nitrile/urethane rubber composition.
It can be used in amounts of parts by weight. As plasticizers, process oil, DOP (dioctyl phthalate), DOS (
(diochytyl sebacate), vegetable oil, factice, etc.

[0035] Such a plasticizer can be used generally in an amount of 5 to 50 parts by weight per 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 generally in an amount of 0.5 to 3 parts by weight per 100 parts by weight of the nitrile/urethane rubber composition. As an anti-aging agent, 2,6-
Examples include di-tert-butyl-4-methylphenol, N-isopropyl-N'-phenyl-p-phenylenediamine, poly(2,2,4-trimethyl-1,2-dihydroquinoline), and special waxes. can.

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

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

Next, the kneaded product obtained as described above is heated and vulcanized to obtain a nitrile/urethane rubber molded product. Specifically, the vulcanization molding is carried out by filling a mold having a desired shape with the kneaded material, and heating the mixture at 140 to 230°C, preferably 150 to 180°C, for 3 to 60 minutes, preferably 1
This is done by heating for 0 to 30 minutes.

Generally, even if nitrile rubber and urethane rubber are mixed, since both have high viscosity and low fluidity, they are only physically mixed, and a network (entanglement) occurs at the molecular level. is not formed. Therefore, a molded product obtained by simply vulcanizing nitrile rubber mixed with urethane rubber does not have improved mechanical strength compared to a nitrile rubber molded product.

In contrast, in the present invention, a vulcanizing agent is added to a nitrile/urethane rubber composition consisting of a nitrile rubber and a urethane rubber forming material, kneaded, and then vulcanized and molded. A rubber molded article having excellent chemical resistance and mechanical strength such as tensile strength and abrasion 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 is composed of (a) polyol and (b) polyisocyanate as described above, and is mixed with nitrile rubber [I] to form urethane rubber into the nitrile rubber. Evenly distributed. When a rubber composition consisting of such urethane rubber forming material [II] and nitrile rubber [I] is heated and vulcanized, the urethane rubber forming material reacts and polymerizes, and
It is considered that it also reacts with nitrile rubber, forming a network at the molecular level of nitrile molecular chains and urethane molecular chains.

The nitrile/urethane rubber molded article according to the present invention obtained as described above maintains the excellent oil resistance, chemical resistance, and heat resistance inherent to nitrile rubber itself, and has high tensile strength and abrasion resistance. It also has excellent mechanical strength.

[0044]

[Effects of the Invention] According to the present invention, nitrile/urethane has improved mechanical strength such as tensile strength and abrasion resistance while maintaining the excellent oil resistance, chemical resistance, and heat resistance inherent to nitrile rubber itself. Rubber molded bodies can be manufactured.

[0045] The present invention will be explained below with reference to Examples.
The present invention is not limited to these examples.

[0046]

[Examples 1 and 2] Rubber mastication rolls were
The rolls were preheated to 80° C., and each component shown in Table 1 below was filled into the roll and kneaded at 80° C. for 60 minutes.

[0047] The kneaded material thus obtained was heated to 160
It was heated to ℃ and vulcanization molded. Table 1 shows the physical properties of the obtained molded product.

[0048]

[Comparative Example 1] Nitrile rubber was made with the ingredients shown in Table 1.
The molded product was heated to 160° C. and vulcanized to obtain a molded product.

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

[0050]

[Comparative Example 2] Nitrile rubber and urethane rubber were mixed at 70°C for 30 minutes using the ingredients shown in Table 1.

The mixture thus obtained was heated to 160
It was heated to ℃ and vulcanization molded to obtain a molded body. Table 1 shows the physical properties of the obtained molded product.

[0052]

[Table 1]

Claims (2)

[Claims] Claim 1: [I] Nitrile rubber; 100 parts by weight;
II] Urethane rubber forming material containing (a) a polyol having two or more hydroxyl groups in the molecule, and (b) a polyisocyanate having two or more isocyanate groups in the molecule; 20
A method for producing a nitrile/urethane rubber molded article, which comprises adding a vulcanizing agent to a nitrile/urethane rubber composition comprising 60 parts by weight, kneading the mixture, heating and vulcanization molding. 2. The method for producing a nitrile/urethane rubber molded article according to claim 1, wherein (a) the polyol is liquid.