JP2008055608A - Vulcanized rubber laminate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a vulcanized rubber laminate composed of an acrylic rubber composition layer used for an inner pipe or the like of various hoses for automobiles and a chlorinated polyethylene rubber composition layer used in an outer skin and excellent in adhesiveness. <P>SOLUTION: A layer (a), which comprises a vulcanizable composition prepared by compounding an ammonium-based vulcanizing agent with an acrylic rubber containing an epoxy group as a crosslinking group, and a layer (b), which comprises a vulcanizable composition prepared by compounding a thiadiazole-based vulcanizing agent with a chlorinated polyethylene rubber, are vulcanized and bonded to obtain the vulcanized rubber laminate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a vulcanized rubber laminate obtained by stacking a chlorinated polyethylene rubber composition layer and an acrylic rubber composition layer and vulcanizing and bonding them. This type of vulcanized rubber laminate is suitably used for, for example, a multilayer hose for automobiles.

In order to obtain a vulcanized rubber laminate, a method of vulcanizing and bonding two types of rubber layers having different characteristics is generally performed. For example, a laminate of a rubber layer having heat resistance and weather resistance and a rubber layer having oil resistance is obtained by vulcanization adhesion of these two layers, and has both characteristics. If the adhesiveness is not good, a practical problem occurs.

For example, peeling between two layers may occur due to insufficient adhesion between the two layers, and gas or liquid that has permeated into the peeling portion from the inner layer may accumulate here and cause swelling. In such a case, when such a rubber laminated product is mounted on a car as a part, the expansion and contraction of the hose is repeated due to the rise and fall of the ambient temperature and the rise and fall of the internal pressure of the hose, and the mechanical strength at the bulge generating portion is increased. There is a risk of hose rupture in the worst case.

Regarding the method of bonding the chlorinated polyethylene rubber layer and the acrylic rubber layer, Patent Document 1 exemplifies acrylic rubber as a low swelling rubber composition, and chlorinated polyethylene rubber as a rubber composition containing other rubber compound. Examples of molding methods of these two compositions include a two-layer coextrusion method using an extruder, an inner tube rubber layer formed by an extruder, and an outer tube rubber layer extruded by another extruder, and then these layers are overlapped. A method for sulfur bonding is described.

However, when the chlorinated polyethylene rubber layer and the acrylic rubber layer are vulcanized and bonded, the vulcanizing agent used in the chlorinated polyethylene rubber composition and the type of acrylic rubber used in the acrylic rubber composition can provide good vulcanized adhesive strength. Is not described.

Patent Document 2 describes an organic peroxide as a vulcanizing agent blended in a chlorinated polyethylene rubber composition and a vulcanizing agent blended in an acrylic rubber composition. According to this document, the interlayer adhesive strength between the chlorinated polyethylene rubber composition and the acrylic rubber composition is improved, but it is the delamination that is measured in the adhesive strength test of the laminate. There is no description of rubber layer breakage, which is a phenomenon that occurs when the material is firmly bonded.
JP-A-11-310678 Japanese Patent Laid-Open No. 2005-199564

The present inventors diligently aiming to obtain an automotive hose obtained by firmly bonding a vulcanized rubber laminate, for example, an inner tube made of an acrylic rubber composition and an outer skin made of a chlorinated polyethylene rubber composition. As a result of research, a layer made of a composition in which a specific vulcanizing agent is blended with acrylic rubber having an epoxy group as a crosslinking group, and a layer made of a composition in which a specific vulcanizing agent is blended with chlorinated polyethylene rubber, The vulcanized rubber laminate of the present invention has been found to exhibit a strong adhesive property of breaking the rubber layer, and the present invention has been completed.

The present invention includes:
(A) a layer comprising a vulcanizing composition in which an acrylic vulcanizing agent is blended with an acrylic rubber having an epoxy group as a crosslinking group;
(B) a layer comprising a vulcanizing composition in which a thiadiazole-based vulcanizing agent is blended with chlorinated polyethylene rubber;
The present invention relates to a vulcanized rubber laminate obtained by vulcanization adhesion.

The present invention also relates to an automotive rubber hose comprising the vulcanized rubber laminate and having an acrylic rubber composition as the innermost layer.

According to the present invention, a laminate in which a chlorinated polyethylene rubber composition layer and an acrylic rubber composition layer are firmly bonded can be obtained, and the characteristics of the rubber polymer of each layer can be utilized as they are. Therefore, this laminate is useful in fields where oil resistance, heat resistance, weather resistance, and ozone resistance are required, such as hoses for various parts of automobiles, and in particular, automatic transmission fluid (ATF), power steering oil, It is preferable for piping hoses such as engine oil.

The acrylic rubber used in the present invention is an acrylic rubber having an epoxy group as a crosslinking group. The structural unit of the crosslinking group has an ethylenically unsaturated group and an epoxy group in the structural unit such as allyl glycidyl ether, methallyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

Usually, these structural units are copolymerized in the range of 1 to 10 mol%, preferably in the range of 1 to 7 mol% with respect to the main structural unit. If it is less than this range, the vulcanization characteristics of the resulting acrylic rubber will be poor, and it will take time for vulcanization. If it exceeds this range, the physical properties of the vulcanized rubber will tend to adversely affect the heat aging resistance.

As main structural units, alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate and butyl acrylate, and acrylic acid esters such as alkoxy acrylates such as methoxyethyl acrylate and ethoxyethyl acrylate are copolymerized alone or in combination of two or more. Used for. Further, rubbers obtained by copolymerizing these acrylic acid esters and monomers such as ethylene and vinyl acetate copolymerizable with the acrylic acid esters are also included in the acrylic rubber of the present invention.

As the vulcanizing agent for the acrylic rubber of the present invention, an ammonium vulcanizing agent is used, and the ammonium vulcanizing agent is preferably an organic ammonium carboxylate such as ammonium benzoate, ammonium phthalate, or ammonium acetate. In view of adhesive strength, ammonium benzoate is particularly preferable.

The compounding quantity of the ammonium type vulcanizing agent used for this invention is 0.1-8 weight part with respect to 100 weight part of acrylic rubber, Preferably it is 0.3-5 weight part. If it is less than this range, the vulcanization rate is slow and not practical, and if it exceeds this range, the rubber layer tends to be scorched and the workability may be adversely affected.

The chlorinated polyethylene rubber used in the present invention may be any chlorinated polyethylene having any chlorine content, crystallinity, and molecular weight distribution, and in particular, chlorine obtained by chlorinating polyethylene having a melt index of 0.01 to 100 Amorphous or substantially amorphous chlorinated polyethylene with a content of 20-50% by weight is preferred.

On the other hand, chlorinated polyethylene may be obtained by chlorinating polyethylene powder or particles in an aqueous suspension or in an organic solvent, but obtained by chlorination in an aqueous suspension. Is preferred. The polyethylene used as a raw material is an ethylene homopolymer or a copolymer with a comonomer copolymerizable with ethylene. Examples of comonomers include: α-olefins such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 4-methyl-pentene-1; acetates such as vinyl acetate and ethyl acetate; ) Acrylic acid; (meth) acrylic acid esters such as methyl (meth) acrylate and ethyl (meth) acrylate. The weight average molecular weight of polyethylene is preferably 40,000 to 700,000, more preferably 50,000 to 300,000.

The polyethylene used as a raw material may be a blend of amorphous chlorinated polyethylene made of low-density polyethylene as a raw material in addition to high-density polyethylene.

A thiadiazole vulcanizing agent is used for the chlorinated polyethylene rubber. Examples of the thiadiazole-based vulcanizing agent include compounds represented by the following formulas (I) (II) (III) (IV) and (V).

In the formulas (I) and (II), R ₁ and R ₂ may be the same or different from each other, and are a hydrogen atom, a group — (C═O) R ₃ , or a group —R ₄ OR ₅ . is there. Here, R ₃ is an alkyl group having 1 to 17 carbon atoms, an aryl group having one or two rings, an aralkyl group having 7 to 8 carbon atoms, or a cyclohexyl group, and R ₄ and R ₅ are the same as each other. It may be different or different, and is an alkyl group having 1 to 8 carbon atoms.

In the formulas (III) and (IV), R ₆ and R ₇ may be the same as or different from each other, are alkyl groups having 1 to 8 carbon atoms, and R ₈ and R ₉ are the same as each other. It may be present or different, and is a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, n is 1 to 2, and X is an oxygen atom or a sulfur atom.

Examples of thiadiazole vulcanizing agents include 2,5-dimercapto-1,3,4-thiadiazole, monobenzoate derivatives of 2,5-dimercapto-1,3,4-thiadiazole, and 2,5-dimercapto-1,3, Examples of the dibenzoate derivatives of 4-thiadiazole include 2,5-dimercapto-1,3,4-thiadiazole, 5-mercapto-1,3,4-thiadiazole-2-thiobenzoate, 1 , 3,4-thiadiazolyl-2,5-dithiobenzoate, 5-mercapto-1,3,4-thiadiazole-2-thiostearate, 5-mercapto-1,3,4-thiadiazole-2-thio-1 Naphthoate, 5-mercapto-1,3,4-thiadiazole-2-thiophenyl acetate, 5-mercapto-1 3,4-thiadiazole-2-thiocyclohexylcarboxylate, 5-mercapto-1,3,4-thiadiazole-2-thio-p-toluate, 5-mercapto-1,3,4-thiadiazole-2-thiocinnamate 2,5-dithio (butoxymethyl) -1,3,4-thiadiazole, 2,2'-dimercapto-5,5'-dithiobis (1,3,4-thiadiazole), 2,2'-di (butoxy) Methyl) -5,5'-dithiobis (1,3,4-thiadiazole), 5,5'-dithiobis (1,3,4-thiadiazole) -2 (3H) -thione.

The compounding amount of the thiadiazole-based vulcanizing agent used in the present invention is 0.1 to 6 parts by weight, preferably 0.5 to 4 parts by weight with respect to 100 parts by weight of the chlorinated polyethylene rubber. Below this range, vulcanization will not proceed sufficiently, and physical properties such as tensile strength, reduction of compression set, oil resistance, and heat aging resistance of chlorinated polyethylene rubber will not be exhibited. It is not suitable for use, and if it exceeds this range, the scorch time of the same layer is shortened, storage stability is poor, and processability tends to be adversely affected.

In the chlorinated polyethylene rubber and acrylic rubber in the present invention, in addition to the above-mentioned crosslinking component, various compounding agents usually used for adjusting various physical properties such as acid acceptor, reinforcing agent, filler, plasticizer A vulcanizing composition can be produced by optionally adding processing aids, stabilizers, anti-aging agents, lubricants, ultraviolet absorbers, pigments, flame retardants, foaming agents and the like.

The composition for vulcanization in the present invention is a mixture of rubber components using any means utilized in the field of rubber processing of chlorinated polyethylene rubber and acrylic rubber, for example, a mixing roll, a Banbury mixer, various kneaders, It can be prepared by kneading, adding a vulcanizing agent component thereto, mixing and kneading.

In order to produce the laminate in the present invention, the chlorinated polyethylene rubber composition layer is obtained by any method such as a method using an extruder, an injection molding machine, a transfer molding machine, or simply superposing both unvulcanized rubber sheets. And an acrylic rubber composition layer are laminated to produce a laminate, or vulcanized by heating at the same time as the production. Heating is performed by an arbitrary method such as heating by steam can, air bath, infrared ray, microwave, lead vulcanization. Usually, the thickness of each sheet is 0.02 to 10 mm, and vulcanization is performed by heating at 100 to 250 ° C. for 1 to 300 minutes.

When producing a laminated hose comprising these vulcanizing compositions, it is preferable that the innermost layer be an acrylic rubber layer having excellent heat resistance and oil resistance. A known production method can be adopted as a method for producing a laminated hose, but a sequential extrusion method in which an acrylic rubber composition for an inner layer is extruded into a cylindrical shape, and then a chlorinated polyethylene rubber composition for an outer layer is extruded, A hose is produced by a method in which an acrylic rubber composition for an inner layer and a chlorinated polyethylene rubber composition for an outer layer are coextruded and vulcanized after molding.

The laminated hose may have a reinforcing yarn interposed between an inner layer and an outer layer. By interposing the reinforcing yarn, the pressure resistance of the hose increases.

Next, in order to specifically explain the present invention, some examples of the present invention and comparative examples for showing comparison with the examples will be given.

a) Preparation of the chlorinated polyethylene rubber composition Among the chlorinated polyethylene rubber composition components shown in Table 1, the components other than the vulcanizing agent and the accelerator were kneaded for 5 minutes with a kneader heated to 120 ° C, and then this kneading. The product was taken out and formed into a sheet with a mixing roll heated to 80 ° C. to obtain an A-kneaded material. A vulcanizing agent and an accelerator were added to this A kneaded material and kneaded with a mixing roll heated to 80 ° C. to obtain a chlorinated polyethylene rubber vulcanizing composition.

As a physical property before vulcanization of the obtained composition, a Mooney scorch test (measured with Mooney Viscometer SMV-201 manufactured by Shimadzu Corporation according to JIS K 6300-1) was performed, and vulcanization characteristics (JIS K 6300-2) were obtained. And measured with a flat die rheometer VR-3110 manufactured by Ueshima Seisakusho. Similarly, a chlorinated polyethylene rubber vulcanized composition obtained in the same manner and sheeted to a thickness of about 2 mm is placed in a mold and subjected to pressure molding at 160 ° C. and 80 Kg / cm ² for 30 minutes as primary vulcanization. did. The sheet having a thickness of about 2 mm obtained by the primary vulcanization was heated for 4 hours in air heated in a 150 ° C. electric oven as the secondary vulcanization. The mechanical strength of each vulcanized product thus obtained was measured by JIS K-6251 (vulcanized rubber tensile test method) and JIS K-6253 (vulcanized rubber hardness test method). The results are shown in the lower part of Table 1.

1) Chlorinated polyethylene rubber H-135: Chlorinated polyethylene (trade name “Daisolac H-135”, manufactured by Daiso, chlorine content 35%) 100 parts by weight C-130: Chlorinated polyethylene (trade name “Daisolac C-130” 100% by weight 2) Vulcanizing agent / thiadiazole vulcanizing agent MTD: 2,5-dimercapto-1,3,4-thiadiazole (trade name “Banchem DMTD”, Vanderbilt 2 parts by weight DBTT: 5,5′-dithiobis (1,3,4-thiadiazole) -2 (3H) -thione (prototype product name “Actor DBTT”, prototype of Kawaguchi Chemical Industry Co., Ltd.) 2.5 weight Part, triazine vulcanizing agent OF: 2,4,6-trimercaptotriazine (trade name "OF-100", manufactured by Daiso Corporation) 1.3 parts by weight, sulfur type vulcanizing agent Agent sulfur: 0.5 parts by weight Organic peroxide vulcanizing agent DCP: Dicumyl peroxide (trade name “Park Mill D”, manufactured by NOF Corporation) 2.5 parts by weight 3) Accelerator # 8: Acetaldehyde- Aniline condensate (trade name “NOXELLA 8”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 1.5 parts by weight M181: dicyclohexylamine salt of 2-mercaptobenzothiazole (trade name “M-181”, manufactured by Daiso Corporation) 5 parts by weight # 22: ethylenethiourea 2.5 parts by weight TAIC: triallyl isocyanurate (trade name “TAIC”, manufactured by Nippon Kasei Co., Ltd.) 2.5 parts by weight 4) acid acceptor ZEO: synthetic zeolite (trade name “Mizuka” Riser DS ", manufactured by Mizusawa Chemical Co., Ltd.) 10 parts by weight MG: Magnesia (trade name" Kyowa Mug # 150 ", manufactured by Kyowa Chemical Industry Co., Ltd.) 10 parts by weight 5) Plasticizer n-TOT : Tri-n-octyl trimellitate (trade name [Trimex N-08], manufactured by Kao Co., Ltd.) 50 parts by weight 6) Reinforcing agent carbon black: (trade name “Seast SO”, manufactured by Tokai Carbon Co., Ltd.) 85 parts by weight b) Preparation of Acrylic Rubber Composition Among the acrylic rubber composition components shown in Table 2, components other than the vulcanizing agent were kneaded for 5 minutes with a kneader heated to 100 ° C., and then the kneaded product was taken out to 80 ° C. To a sheet with a mixing roll warmed to obtain A-kneaded material. A vulcanizing agent was added to the kneaded material A and kneaded with a mixing roll heated to 80 ° C. to obtain a composition for vulcanizing acrylic rubber.

As a physical property before vulcanization of the obtained composition, a Mooney scorch test (measured with Mooney Viscometer SMV-201 manufactured by Shimadzu Corporation according to JIS K 6300-1) was performed, and vulcanization characteristics (JIS K 6300-2) were obtained. And measured with a flat die rheometer VR-3110 manufactured by Ueshima Seisakusho. Similarly, the acrylic rubber vulcanized composition obtained in the form of a sheet having a thickness of about 2 mm was placed in a mold and subjected to pressure molding at 160 ° C. and 80 kg / cm ² for 30 minutes as primary vulcanization. The sheet having a thickness of about 2 mm obtained by the primary vulcanization was heated for 4 hours in air heated in a 150 ° C. electric oven as the secondary vulcanization. The mechanical strength of each vulcanized product thus obtained was measured by JIS K-6251 (vulcanized rubber tensile test method) and JIS K-6253 (vulcanized rubber hardness test method). The results are shown in the lower part of Table 2.

1) Acrylic rubber epoxy type: Trade name “Toaaclon AR-601”, manufactured by Toa Paint Co., Ltd. 100 parts by weight Chlorine: Product name “Noxtite A-1095”, manufactured by NOK Co., Ltd. 100 parts by weight Active chlorine type: Product name “Knox” Tight PA-401 ", 100 parts by weight manufactured by NOK Corporation 2) Vulcanizing agent / AB (ammonia-based vulcanizing agent):
Ammonium benzoate (trade name “Barnock AB-S”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) 2 parts by weight PZ / TTFE (dithiocarbamate vulcanizing agent):
2 parts by weight of zinc dimethyldithiocarbamate (trade name “Noxeller PZ”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) / 0.5 parts by weight of iron dimethyldithiocarbamate (trade name “Noxeller TTFE”, manufactured by Ouchi Shinsei Chemical Co., Ltd.) S / SN / SK (sulfur vulcanizing agent / metal soap):
Sulfur (colloidal sulfur, manufactured by Hosoi Chemical Co., Ltd.) 0.3 parts by weight / sodium stearate (trade name “NS Soap”, manufactured by Kao) 2.5 parts by weight / potassium stearate (special reagent grade) 0.3 parts by weight 3) Lubricant fatty acid ester (trade name “Stractol WB212”, manufactured by S & S Japan) 2 parts by weight 4) Reinforcing agent carbon black (trade name “Seast SO”, manufactured by Tokai Carbon Co., Ltd.) 60 parts by weight 5) Antiaging agent diphenylamine System Substituted diphenylamine (trade name “Naugard 445”, manufactured by Shiraishi Calcium Co., Ltd.) 2 parts by weight c) Preparation of vulcanized rubber laminate A sheet (thickness of about 2 mm) comprising the chlorinated polyethylene rubber vulcanizing composition shown in Table 1. And the sheet | seat (thickness of about 2 mm) which consists of a composition for acrylic rubber vulcanization | cure of Table 2 is put in a metal mold | die in accordance with the row direction, respectively. As the next vulcanization, pressure molding was performed at 160 ° C. and 80 kg / cm ² for 30 minutes. A laminated sheet having a thickness of about 4 mm obtained by the primary vulcanization was heated in air heated in an electric oven at 150 ° C. for secondary vulcanization for 4 hours. The obtained laminate was cut from the laminated vulcanized sheet with a test piece width of 1 cm with reference to JIS K 6256 (cloth and rubber peel test), and the moving speed of the gripping jig was set to 50 mm / min. Was measured. The results are shown in Table 3 and Table 4.

From the above results, when using a thiadiazole-based vulcanizing agent for the chlorinated polyethylene rubber composition layer and an ammonium-based vulcanizing agent for the acrylic rubber composition layer having an epoxy-based crosslinking group, chlorination Regardless of the accelerator and acid acceptor of the polyethylene rubber composition, it can be seen that a sheet obtained by laminating and vulcanizing both composition layers exhibits excellent adhesive strength (that is, rubber layer breakage in a peel test).

Claims (4)

(A) a layer comprising a vulcanizing composition in which an acrylic vulcanizing agent is blended with an acrylic rubber having an epoxy group as a crosslinking group;
(B) a layer comprising a vulcanizing composition in which a thiadiazole-based vulcanizing agent is blended with chlorinated polyethylene rubber;
A vulcanized rubber laminate obtained by vulcanization adhesion. The vulcanized rubber laminate according to claim 1, wherein the ammonium vulcanizing agent is ammonium benzoate. The vulcanized rubber laminate according to claim 1, wherein the thiadiazole vulcanizing agent is 2,5-dimercapto-1,3,4-thiadiazole. An automotive rubber hose comprising the vulcanized rubber laminate according to any one of claims 1 to 3 and having an acrylic rubber composition as an innermost layer.