JPH11300892A - Vulcanized nitrile rubber laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate comprising a vulcanized rubber compsn. excellent in fuel impermeability and cold resistance. SOLUTION: In a laminate of which the inner and outer layers are formed from a vulcanized rubber compsn. containing at least nitrile rubber, the outer layer comprises a vulcanizate of a rubber compsn. containing NBR with a bonded acrylonitrile monomer content of 15-45 wt.% as a rubber component and the inner layer comprises a vulcanizate of a rubber compsn. containing NBR with a bonded acrylonitrile monomer content of 43-60 wt.% as a rubber component (wherein the bonded acrylonitrile content of NBR of the inner layer is larger than that of NBR of the outer layer).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber laminate comprising two layers of vulcanized nitrile rubber, and more particularly to a rubber laminate having excellent cold resistance and automobile fuel permeability.

[0002]

2. Description of the Related Art Conventionally, nitrile rubbers represented by acrylonitrile-butadiene copolymer rubber (hereinafter sometimes referred to as "NBR") have been used for fuel hoses for automobiles. However, since the ozone resistance is not always sufficient, the use of NBR is insufficient in durability, and a mixture of NBR and polyvinyl chloride resin (usually, (Called a polyblend).

[0003] However, in recent years, materials having excellent fuel permeation resistance have been demanded in accordance with fuel emission regulations. Conventionally used polyblends cannot sufficiently satisfy this demand, and the NBR in the polyblend has been required. The use of NBR with an increased amount of acrylonitrile has been studied. Although the use of such a polyblend improves fuel permeation resistance, it is inferior in cold resistance and poses a practical problem.

As a rubber material for a filler hose, fluorine rubber having excellent fuel permeability is conventionally used. However, fluorine rubber has poor cold resistance, and NBR or polyblend is used as an outer layer to improve the cold rubber. A hose having a laminated structure to be used is being studied. However, the vulcanization adhesion of fluororubber with NBR or polyblend is extremely difficult, and a vulcanization system for improving vulcanization adhesion is disclosed in JP-A-63-2527.
Although it is proposed in Japanese Patent Publication No. 36, the cost is high due to the use of special additives.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide not only fuel permeation resistance but also cold resistance and vulcanization adhesion. An object of the present invention is to provide a laminate comprising a vulcanized rubber composition. The inventor of the present invention has conducted intensive studies to achieve this object. As a result, the outer layer was formed of a vulcanized rubber layer containing medium-high NBR, and the inner layer in contact with fuel was formed of a vulcanized rubber layer containing extremely high NBR. Have been achieved, and the present invention has been completed based on this finding.

[0006]

Thus, according to the present invention, in a laminate in which an inner layer and an outer layer are respectively formed by a vulcanized rubber composition containing at least a nitrile rubber, the outer layer is a bonded unsaturated nitrile-based rubber as a rubber component. 1 monomer
A rubber composition comprising a vulcanizate of a rubber composition containing 5 to 45% by weight of a nitrile rubber, and an inner layer containing a nitrile rubber having a bound unsaturated nitrile monomer amount of 43 to 60% by weight as a rubber component. Wherein the nitrile rubber forming the inner layer has a larger amount of bonded unsaturated nitrile monomers than the rubber forming the outer layer, thereby providing a vulcanized nitrile rubber laminate.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to embodiments. The nitrile rubber used in the present invention includes a copolymer obtained by copolymerizing an unsaturated nitrile monomer and a conjugated diene monomer, and a nitrile group obtained by hydrogenating a conjugated diene monomer portion of the copolymer. Highly saturated rubber is included. The nitrile group-containing highly saturated rubber preferably has an iodine value of 0 to 120 in order to satisfy required performances such as heat resistance and sour gasoline resistance.
-100 are more preferred.

Specific examples of unsaturated nitrile monomers include, for example, acrylonitrile, methacrylonitrile,
α-chloroacrylonitrile and the like. Examples of the conjugated diene monomer include 1,3-butadiene, 2,3-dimethylbutadiene, isoprene, 1,3
-Pentadiene and the like. Any of these monomers can be used alone or in combination of two or more. A particularly preferred nitrile rubber is a copolymer rubber of an unsaturated nitrile monomer and a conjugated diene monomer, particularly a copolymer rubber of acrylonitrile and butadiene (NBR).

In the present invention, other than the above-mentioned monomers, other monomers copolymerizable therewith may be used as the conjugated diene-based monomer as long as the effects of the present invention are not impaired. It is also possible to use it instead of a part. The other copolymerizable monomer is not particularly limited, for example, styrene,
Aromatic vinyl monomers such as α-methylstyrene and vinylpyridine; non-conjugated diene monomers such as vinyl norbornene, dicyclopentadiene and 1,4-hexadiene; acrylic acid, methacrylic acid, maleic acid, and maleic anhydride Unsaturated carboxylic acid such as acid; alkyl group having 1 carbon atom
About 10 to about 10 alkyl acrylates and alkyl methacrylates (these have a hydroxyl group, a cyano group, and a carbon number of 1 to 1).
And the alkyl group may have about 1 to 10 carbon atoms, such as a monoalkyl ester of an unsaturated dicarboxylic acid and a dialkyl ester of an unsaturated dicarboxylic acid. Saturated dicarboxylic acid ester monomers and the like can be mentioned. These monomers can be used alone or in combination of two or more.

[0010] The nitrile rubber can be produced by copolymerizing the above-mentioned monomer by a conventionally known polymerization method, for example, emulsion polymerization or the like using a radical initiator. In the laminate of the present invention, a rubber composition containing at least the above nitrile rubber is used to form the inner layer and the outer layer. The Mooney viscosity (ML _{1 + 4} , 100 ° C.) of the nitrile rubber is not particularly limited.
~ 95 are used.

The nitrile rubber used for forming the inner layer is as follows:
The amount of the unsaturated unsaturated nitrile monomer in the rubber is 43 to 60.
% By weight, preferably 43 to 53% by weight, more preferably 44 to 52% by weight, with the balance being a copolymer rubber having a conjugated diene monomer. If the amount of the unsaturated unsaturated nitrile monomer is less than 43% by weight, the fuel permeability of the laminate is insufficient, and if it exceeds 60% by weight, the cold resistance of the laminate deteriorates, which is not preferable.

On the other hand, the nitrile rubber used for forming the outer layer is such that the amount of the unsaturated unsaturated nitrile monomer in the rubber is 15%.
To 45% by weight, preferably 22 to 43% by weight, more preferably 28 to 42% by weight, and the remainder is a conjugated diene monomer. When the amount of the bond unsaturated nitrile monomer is less than 15% by weight, the oil resistance of the laminate becomes insufficient, and when it exceeds 45% by weight, the cold resistance of the laminate becomes insufficient, which is not preferable.

Further, in the present invention, in order to maintain good fuel permeation resistance, the nitrile rubber used for forming the inner layer always has a larger amount of bound unsaturated nitrile than the rubber used for forming the outer layer. Is required, the difference is 2% by weight
More preferably, the difference is more than 3% by weight.

Further, in the present invention, by using each of the above-mentioned nitrile rubbers as a mixture with a vinyl chloride resin (generally referred to as a polyblend), the laminate of the present invention has a high durability. Ozone properties, oil resistance and the like can be further improved. The vinyl chloride resin used in the present invention is not particularly limited, but usually has an average degree of polymerization of 600.
Approximately 2,000 are used. The mixing ratio of the nitrile rubber and the vinyl chloride resin in the polyblend is usually 95 to 50% by weight, preferably 85 to 60% by weight of the nitrile rubber and 5 to 50% by weight, preferably 15 to 50% by weight of the vinyl chloride resin. 40% by weight.

Also in the polyblend, the nitrile rubber is preferably a copolymer rubber of an unsaturated nitrile monomer and a conjugated diene monomer, especially a copolymer rubber of acrylonitrile and butadiene (NBR). As the vinyl resin, a vinyl chloride resin (PVC) is preferable.
In a polyblend of NBR and PVC, NBR7
A mixture of 0% by weight and 30% by weight of PVC is generally frequently used. The method for producing such a polyblend is not particularly limited, but usually, a dry blending method in which a nitrile rubber and a vinyl chloride resin powder are mixed at a high temperature in a kneader such as a Banbury mixer, or a mixture of these in a latex state and coagulated. After drying, a known method such as a latex coprecipitation method in which a heat treatment is performed using a kneader such as an extruder or a Banbury mixer can be used.

In the present invention, the vulcanizable rubber composition forming the inner layer and the outer layer comprises the above nitrile rubber and a vulcanizing agent,
If necessary, it can be prepared by mixing and kneading various compounding agents usually used in the rubber industry and the plastics industry using an ordinary mixer such as a roll or a Banbury mixer.

As a vulcanizing agent for nitrile rubber, usually,
Any of known sulfur-based vulcanizing agents and organic peroxide crosslinking agents used as vulcanizing agents for NBR can be used,
There is no particular limitation. Examples of the sulfur-based vulcanizing agent include sulfur or sulfur-donating compounds (thiuram-based compounds, morpholine-based compounds, and the like). Sulfur vulcanizing agents are usually used together with vulcanization aids such as zinc white and stearic acid and various vulcanization accelerators (thiuram type, guanidine type, sulfenamide type, thiazole type, dithiocarbamate type, etc.). You. In the present invention, the amount of the sulfur-based vulcanizing agent or the vulcanization accelerator is not particularly limited.
Usually 0.3 to 10 parts by weight and 1 to 5 parts by weight per part by weight.

As the organic peroxide crosslinking agent, usually, an organic peroxide or a combination of the organic peroxide and a crosslinking aid is used. As the organic peroxide, for example, dicumyl peroxide,
Di-t-butyl peroxide, t-butyl cumyl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, 2,5-dimethyl-
2,5-di (t-butylperoxy) hekinsin-3,
1,1-di- (t-butylperoxy) -3,3,5-
Examples include trimethylcyclohexane, t-butylperoxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, 1,3-di (t-butylperoxyisopropyl) benzene, and the like.

As the cross-linking aid, compounds having a polyunsaturated bond in the molecule used in ordinary organic peroxide cross-linking are used. For example, triallyl cyanurate, triallyl isocyanurate, trimethylol Examples include polyfunctional monomers such as propane trimethacrylate, ethylene dimethacrylate, diallyl phthalate, toluylene bismaleimide, metaphenylene bismaleimide, and divinylbenzene, and liquid vinyl polybutadiene. In the present invention, the amounts of the organic peroxide and the crosslinking aid are not particularly limited, and are usually 0.3 to 10 parts by weight and 1 to 5 parts by weight, respectively, per 100 parts by weight of the nitrile rubber.

Examples of the compounding agents other than the above vulcanization system include reinforcing agents such as carbon black and silica, fillers such as calcium carbonate, softeners, plasticizers, antioxidants, stabilizers and processing aids. Can be used. In the present invention, the type and amount of other compounding agents other than the vulcanizing system are not particularly limited, and can be appropriately selected and determined so as to satisfy the characteristics and the like required for the laminate. In the present invention, rubber components other than the above-mentioned nitrile rubbers, for example, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, ethylene oxide /
Epichlorohydrin copolymer rubber, ethyl acrylate / 2
A rubber such as a chloroethyl vinyl ether co-weight rubber, EPDM or the like, as long as the effects of the present invention are not impaired;
Alternatively, it can be used for a rubber composition for forming an outer layer.

Since the laminate of the present invention uses the same type of nitrile rubber, there is no need for a special method for firmly bonding the inner layer and the outer layer during the production of the rubber laminate. It has an advantage that the composition can be easily adhered by repeatedly vulcanizing the composition. Each of the rubber compositions forming the inner layer and the outer layer obtained above is, for example, extruded into two sheet-shaped rubber composition layers having a predetermined thickness, or the inner layer is extruded into a tube shape, and Are each formed into a hose by a two-layer extrusion method or the like. As these molding methods, conventionally known molding methods can be used, and there is no particular limitation.

Next, the two composition layers in the form of a sheet are superposed in an unvulcanized state, and are subjected to pressure vulcanization using a hot press or a vulcanizing can to vulcanize and bond the two vulcanizable rubber compositions. To obtain a rubber laminate. The two rubber composition layers formed in a hose shape are vulcanized under pressure using a vulcanizer, and the two composition layers are vulcanized and bonded to each other. In the present invention, the vulcanization conditions are not particularly limited, but vulcanization by hot pressing is usually performed at a temperature of 140 ° C to 200 ° C for 20 to 150k.
Vulcanization by a vulcanizer under a pressure of gf / cm ² under a pressure of 1.8 to 5.5 kgf / cm ² at a temperature of 130 ° C. to 160 ° C. 30-120
It is performed under the condition of minutes.

In the present invention, when a fuel hose is manufactured as a laminate, the laminate of the present invention formed into a tube by a two-layer extrusion method is used as an inner tube rubber layer, and a polyester fiber or the like is added thereto. The reinforcing yarn layer is knitted by braiding at an appropriate knitting angle, and a vulcanizable rubber composition having a rubber component of epichlorohydrin rubber, chloroprene rubber, chlorosulfonated polyethylene, chlorinated polyethylene, acrylic rubber, etc. is further provided on the outside thereof. It can be extruded and coated as a weatherable outer rubber layer. When vulcanizing, a metal mandrel of a predetermined shape may be inserted before vulcanization.

In the present invention, when a diaphragm is manufactured as a laminate, a woven fabric such as polyester or polyamide is used as a base fabric layer, which is punched into a predetermined shape to form a vulcanizable rubber for forming an inner layer and an outer layer. The sheets for forming the inner and outer layers, which are sandwiched or laminated between the composition sheets, are punched into a predetermined shape, and the above-mentioned base cloth is overlaid on at least one surface and press-vulcanized. The rubber laminate of the present invention thus obtained is used in contact with an automobile fuel such as a fuel hose or a diaphragm, and is suitable as a rubber product. In the present invention, the method for producing these rubber products is not particularly limited, and conventionally known methods for producing these rubber products can be used.

[0025]

The present invention will be described more specifically with reference to the following examples and comparative examples. The parts and percentages in these examples are on a weight basis unless otherwise specified.

Examples 1 to 3 and Comparative Examples 1 to 3 According to the compounding recipe shown in Table 1, NBR or polyblend and each compounding agent other than the vulcanizing agent were mixed and kneaded using a small Banbury mixer. The mixture thus obtained was mixed with a vulcanizing agent using a roll and kneaded to produce each vulcanizable rubber composition. Each vulcanizable rubber composition was passed through a gap of 6 inch rolls to form an unvulcanized sheet having a uniform thickness of about 1 mm, and the unvulcanized sheets were overlaid in the combination shown in Table 2 and then 160 ° C. For 20 minutes to obtain a uniform vulcanized laminate having a thickness of 2 mm.

The cold resistance and gasoline permeability of each laminate were measured by the following methods. (1) Cold resistance Measured by a low-temperature bending test method. A 63 mm long, 38 mm wide strip-shaped test piece was punched out of the vulcanized sheet, and one end was fixed in a thermostat adjusted to a predetermined temperature and left horizontally for 3 minutes in a state of being held horizontally in the thickness direction.
A round bar is pressed against the test piece at a descent speed of m / min to bend the test piece, and the occurrence of cracks in the bent portion is checked.
The case where no crack is observed is indicated by NC, and the case where crack is observed is indicated by Crack.

(2) Gasoline permeability Measured by the aluminum cup method. A fixed amount of fuel oil C (isooctane / toluene = 50/50 volume ratio) is charged into an aluminum cup having a capacity of 100 ml, which is covered with a vulcanized sheet cut into a disk having a diameter of 61 mm. (The effective area is 25.5 cm ² ), left in a constant temperature bath at 40 ° C. for a certain period of time, and the transmission coefficient was calculated from the weight loss during that time. The smaller the value, the more difficult the fuel permeates. Table 2 shows the above results.

[0029]

[Table 1] Note: (1) Nipol DN207 manufactured by Zeon Corporation (bound acrylonitrile amount: 33.
(5%) (2) Nipol DN101L manufactured by Zeon Corporation (bound acrylonitrile amount 4
1.5%) (3) Nipol 1000X132 manufactured by Zeon Corporation (Amount of acrylonitrile bound)
(4) Asahi Carbon Co., Ltd. Asahi # 60 (5) Asahi Denka Kogyo Co., Ltd. Adekasizer RS107

[0030]

[Table 2]

From the results shown in Table 2, the vulcanized NBs of Examples 1 to 3
It can be seen that the R laminate is superior in gasoline permeability without impairing cold resistance, as compared to the polyblend single layer using ultra-high and high NBR of the comparative example.

The composition for forming the inner and outer layers in Example 1 and Comparative Example 2 was used to obtain an inner diameter of 40 m by a two-layer extrusion molding method.
m, a hose having an inner layer thickness of 1 mm and an outer layer thickness of 3 mm was prepared. Gasoline permeation resistance is 3
It was cut to a length of 0 cm, and the inside was filled with fuel oil C, and gold-made round bars having a diameter larger than the inner diameter of the hose were inserted into both open ports to close both ends. This was left in a constant temperature bath for a certain period of time in the same manner as above, and the amount of decrease in fuel oil C was measured. The amount of decrease was extremely small in the hose of the present invention, but was extremely large in the hose of the comparative example, so The fuel permeability was poor. For cold resistance, the hose was immersed in the above-mentioned low-temperature bath in the straight state for the same time as above, and the presence or absence of cracks was observed according to the low-temperature test method B of the rubber hose test method of JIS K6330. The result of No. 2 was reproduced.

[0033]

According to the present invention described above, there is provided a laminate having an excellent balance between gasoline permeability and cold resistance, which has been difficult to realize by using a conventional nitrile rubber or a polyblend of the rubber and a vinyl chloride resin. Is done. Further, the laminate of the present invention enables a significant cost reduction as compared with a laminate comprising a conventional polyblend and a fluorine-based rubber or a conventional polyblend and a polyamide resin, and requires excessive gasoline permeation resistance. It is suitable as a fuel hose or diaphragm that is not used.

A preferred embodiment of the present invention is as follows. (1) In claim 1, the amount of the unsaturated unsaturated nitrile monomer in the nitrile rubber for the inner layer is preferably 43 to 53.
%, More preferably 44 to 52% by weight, and the amount of bound unsaturated nitrile monomer in the nitrile rubber for the outer layer is preferably 22 to 43% by weight, more preferably 28 to 43% by weight.
-42% by weight, and the amount of the nitrile rubber for the inner layer is preferably at least 2% by weight, more preferably at least 3% by weight, more than the amount of the unsaturated unsaturated nitrile monomer in the rubber for the outer layer. (2) In claim 1 or (1), at least one of the nitrile rubbers forming the inner and outer layers is a mixture (polyblend) of a nitrile rubber and a vinyl chloride resin. (3) In (2), the mixing ratio of nitrile rubber / vinyl chloride resin is 95 to 50% by weight / 50 to 5% by weight, preferably 85 to 60% by weight / 15 to 40% by weight. (4) In any one of (1) to (3), the nitrile rubber forming the inner and outer layers is an unsaturated nitrile monomer, preferably acrylonitrile and a conjugated diene monomer, preferably butadiene. Or a conjugated diene monomer unit thereof is hydrogenated.

Claims (3)

[Claims] 1. A laminate in which an inner layer and an outer layer are respectively formed of a vulcanized rubber composition containing at least a nitrile rubber, wherein the outer layer contains 15 to 45% by weight of a unsaturated unsaturated nitrile monomer as a rubber component. The inner layer is composed of a vulcanizate of a rubber composition containing a nitrile rubber containing a nitrile rubber having a bound unsaturated nitrile monomer content of 43 to 60% by weight as a rubber component. A vulcanized nitrile rubber laminate, characterized in that the nitrile rubber forming the inner layer has a larger amount of bonded unsaturated nitrile monomers than the rubber forming the outer layer. 2. The vulcanized nitrile rubber laminate according to claim 1, which is used in contact with an automobile fuel. 3. A hose or a diaphragm.
The vulcanized nitrile rubber laminate according to the above.