RUBBER LAMINATE

Abstract

A rubber laminate where an acrylic rubber layer (A) including an acrylic rubber composition including at least a carboxyl group-containing acrylic rubber and an aliphatic polyvalent amine compound or a derivative thereof and a fluororubber layer (B) including a fluororubber composition including at least a polyol-cross-linkable fluororubber and a bismuth oxide are made to adhere to one another through cross-linking.

Claims

1. A rubber laminate comprising: an acrylic rubber layer (A) including an acrylic rubber composition including at least a carboxyl group-containing acrylic rubber and an aliphatic polyvalent amine compound or a derivative of the aliphatic polyvalent amine compound; and a fluororubber layer (B) including a fluororubber composition including at least a polyol-cross-linkable fluororubber and a bismuth oxide, the acrylic rubber layer (A) and the fluororubber layer (B) being made to adhere to one another through cross-linking.

2. The rubber laminate as claimed in claim 1, wherein the carboxyl group-containing acrylic rubber includes monoester monomer units including an , -ethylenic unsaturated dicarboxylic acid having a carbon number of 4 to 12 and alkanol having a carbon number of 1 to 8.

3. The rubber laminate as claimed in claim 2, wherein the carboxyl group-containing acrylic rubber includes , -ethylenic unsaturated carboxylic acid monomer units having a secondary alkyl ester.

4. A hose using the rubber laminate claimed in claim 1.

5. A hose using the rubber laminate claimed in claim 2.

6. A hose using the rubber laminate claimed in claim 3.

Description

EMBODIMENTS

[0067] The present invention will be described in more detail with reference to embodiments, but the present invention is not limited to the embodiments. Hereinafter, parts and percentages are those by weight unless otherwise specified. Tests and evaluations were performed as follows.

[Peel Test]

[0068] A rubber laminate obtained as mentioned above was used to evaluate the property of adhering through cross-linking between the two layers of the rubber laminate through a peel test according to JIS K6854-3. In more detail, strips were punched out from the obtained rubber laminate each of which has a width of 25.4 mm and a length of 100 mm. A grasping section at an end of the rubber laminate was then fastened to a grasping device of a tensile testing machine, and a 180 peel test was performed at a speed of 50 mm/min, while the load upon the peeling was read by the load cell of the tensile testing machine and the peeling strength (N/mm) was obtained. After the peel test, the percentage of the acrylic rubber left on the surface of the fluororubber was measured. In this regard, it is meant that, the higher the percentage of the acrylic rubber is, that is, the higher the percentage of the rubber breakage is, the better the adhesiveness to the fluororubber is. For a case where the peel strength is higher or for a case where the adhesion interface has a rubber breakage state, this means that the rubber laminate has a satisfactory property of adhering through cross-linking.

[Acid Resistance Test]

[0069] An unvulcanized rubber composition of a polyol-cross-linkable fluororubber was press-molded with a 1501502 mm sheet mold at a temperature of 170 C. and a surface pressure of 10 MPa for 20 minutes, followed by oven vulcanization (secondary vulcanization) at 170 C. for 4 hours. A test piece was punched out from the resulting vulcanized rubber sheet for a volume swelling test and was immersed in a test solution at 80 C. for 168 hours to measure the volume swelling. A composition of the test solution was: an aqueous solution containing 50 ppm of a nitric acid, 1500 ppm of a sulfuric acid, 1500 ppm of an acetic acid, 5000 ppm of a formic acid, and 10 ppm of a hydrochloric acid. The pH of the test solution was approximately 2.

[Production of Carboxyl Group-Containing Acrylic Rubber]

FIRST PRODUCTION EXAMPLE

[0070] A polymerization reactor equipped with a thermometer and a stirring device was charged with 200 parts of water, 3 parts of sodium lauryl sulfate, 6 parts of ethyl acrylate, 30 parts of 2-methoxyethyl acrylate, 60 parts of n-butyl acrylate, 1 part of polyethylene glycol dimethacrylate having a weight-average molecular weight of 336, and 3 parts of monocyclohexyl fumarate. Thereafter, after two times of reduced-pressure degassing and nitrogen substitution to adequately remove oxygen, 0.005 parts of cumene hydroperoxide and 0.002 parts of formaldehyde sodium sulfoxylate were added to initiate an emulsion polymerization reaction under the normal pressure and temperature, the reaction was continued until the polymerization conversion rate reached 95%, and a polymerization terminator was added to stop the polymerization. The resulting emulsion polymerization solution was coagulated with an aqueous solution of calcium chloride, washed with water, and dried to obtain a carboxyl group-containing acrylic rubber containing an , -ethylenic unsaturated carboxylic acid having a secondary alkyl ester (1). The composition of the resulting carboxyl group-containing acrylic rubber (1) was: 6% of ethyl acrylate monomer units, 30% of 2-methoxyethyl acrylate units, 60% of n-butyl acrylate monomer units, 1% of polyethylene glycol dimethacrylate units with a weight-average molecular weight of 336, and 3% of monocyclohexyl fumarate units (1.510.sup.2 ephr). The polymer Mooney viscosity (ML1+4, 100 C.) was 48.

SECOND PRODUCTION EXAMPLE

[0071] A polymerization reactor equipped with a thermometer and a stirring device was operated in the same manner as in First Production Example except that 200 parts of water, 3 parts of sodium lauryl sulfate, 58 parts of ethyl acrylate, 40 parts of n-butyl acrylate, and 2 parts of mono-n-butyl fumarate were charged; and a carboxyl group-containing acrylic rubber containing an , -ethylenic unsaturated carboxylic acid having a primary alkyl ester (2) was obtained. The composition of the resulting carboxyl group-containing acrylic rubber (2) was: 58% of ethyl acrylate monomer units, 40% of n-butyl acrylate monomer units, and 2% of mono-n-butyl fumarate monomer units (1.610.sup.2 ephr). The polymer Mooney viscosity (ML1+4, 100 C.) was 40.

THIRD PRODUCTION EXAMPLE

[0072] A polymerization reactor equipped with a thermometer and a stirring device was operated in the same manner as in First Production Example except that 200 parts of water, 3 parts of sodium lauryl sulfate, 48 parts of ethyl acrylate, 48 parts of n-butyl acrylate, and 4 parts of allyl glycidyl ether were charged; and an epoxy group-containing acrylic rubber (3) was obtained. The composition of the epoxy group-containing acrylic rubber (3) was; 48% by weight of ethyl acrylate units, 48% by weight of n-butyl acrylate units, and 4% by weight of allyl glycidyl ether units; the polymer Mooney viscosity (ML1+4, 100 C.) was 35.

FIRST EMBODIMENT

[Preparation of Acrylic Rubber Composition]

[0073] Using a Banbury mixer, 100 parts of a carboxyl group-containing acrylic rubber (1) obtained in First Production Example were kneaded at 50 C. for 5 minutes after adding of 60 parts of carbon black (filler, product name Seast SO, made by Tokai Carbon Co., Ltd., Seast being the registered trademark); 2 parts of a stearic acid (product name STEARIC ACID CAMELLIA (beads), made by NOF Corporation); 1 part of an ester wax (a lubricant (processing aid), product name Gleck G-8205, made by DIC corporation, Gleck being the registered trademark); 2 parts of a 4,4-bis(, -dimethylbenzyl)diphenylamine (an antiaging agent, product name Nocrack CD, made by Ouchi Shinko Chemical Industrial, Nocrack being the registered trademark). The resulting mixture was then transferred to open rolls of 50 C., and 0.5 parts of a hexamethylene diamine carbamate (a cross-linking agent, an aliphatic diamine, product name Diak #1 made by DuPont) and 2 parts of 1,3-di-o-tolylguanidine (a cross-linking accelerator, product name Nocceler DT, made by Ouchi Shinko Chemical Industrial, Nocceler is the registered trademark) were added and kneaded at 50 C. to obtain an acrylic rubber composition A.

[Preparation of Fluororubber Composition]

[0074] 20 parts of carbon black (a filler, product name Thermax MT, made by Cancarb Limited, THERMAX being the registered tradename), 2.5 parts of bisphenol AF-based vulcanizer (a mixture containing bisphenol AF and benzyltriphenyl phosphonium salt at a ratio of approximately 3:1, product name Viton VC #50 made by DuPont), and 10 parts of bismuth oxide (an acid acceptor, product name Bismuth Oxide S, made by Nihon-kagaku-sangyo) were added to 100 parts of a polyol-cross-linkable fluororubber (product name Viton AL600, made by Chemours Company, VITON being the registered tradename); the mixture was kneaded using open rollers at 50 C., so that a fluororubber composition F was obtained.

{Manufacture of Rubber Laminate}

[0075] The thus obtained acrylic rubber composition and fluororubber composition were kneaded with open rolls, respectively. Thereafter, respective sheets having uniform thickness of approximately 2 mm were extracted from the resulting products and were molded into sheet-like products each having a size of 6 cm by 10 cm. The sheet-like products were then laminated together and the laminated products were placed into a metal mold having 6 cm in length, 10 cm in width, and 0.4 cm in depth. Then, the laminated products were caused to adhere together through cross-linking at 170 C. for 20 minutes while being pressurized with a pressing pressure of 10 MPa, followed by secondary vulcanization at 170 C. for 4 hours, to produce a rubber laminate. At this time, in order to prepare for a peel test described above, a cellophane paper sheet was previously inserted at a portion to be grasped between the sheet products to leave the portion where the sheet products did not adhere together. The resulting rubber laminate was then used for the peel test. The results are shown in Tables 1-3.

SECOND EMBODIMENT

[0076] An acrylic rubber composition B was prepared in the same manner as First Embodiment, except that, in preparing the acrylic rubber composition, instead of 0.5 parts of a hexamethylene diamine carbamate, 1.08 parts of a N,N-dicinnamylidene-1,6-hexamethylene diamine (a cross-linking agent, aliphatic diamine derivative, product name Diak #3, made by DuPont) was added; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

THIRD EMBODIMENT

[0077] An acrylic rubber composition C was prepared in the same manner as First Embodiment, except that, in preparing the acrylic rubber composition, instead of the carboxyl group-containing acrylic rubber (1), 100 parts of the carboxyl group-containing acrylic rubber (2) obtained in Second Production Example was used; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

FOURTH EMBODIMENT

[0078] A fluororubber composition G was prepared in the same manner as First Embodiment, except that, in preparing the fluororubber composition, instead of the bismuth oxide, 15 parts of a hydrous bismuth nitrate oxide (an acid acceptor, product name IXE-550, made by Toagosei) was added; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

FIFTH EMBODIMENT

[0079] A fluororubber composition G was prepared in the same manner as Second Embodiment, except that, in preparing the fluororubber composition, instead of the bismuth oxide, 15 parts of the hydrous bismuth nitrate oxide was added; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

SIXTH EMBODIMENT

[0080] A fluororubber composition G was prepared in the same manner as Third Embodiment, except that, in preparing the fluororubber composition, instead of the bismuth oxide, 15 parts of the hydrous bismuth nitrate oxide was added; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

FIRST COMPARATIVE EXAMPLE

[0081] An acrylic rubber composition D was prepared in the same manner as First Embodiment, except that, in preparing the acrylic rubber composition, instead of a hexamethylene diamine carbamate, 1.28 parts of 2,2-bis[4-(4-aminophenoxy)phenyl]propane (a cross-linking agent, an aromatic diamine, product name BAPP, made by Wakayama Seika Kogyo Co., Ltd.) was added; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

SECOND COMPARATIVE EXAMPLE

[0082] An acrylic rubber composition E was prepared in the same manner as First Embodiment, except that, in preparing the acrylic rubber composition, instead of the carboxyl group-containing acrylic rubber (1), 100 parts of the carboxyl group-containing acrylic rubber (3) obtained in Third Production Example was used and the amount of a hexamethylene diamine carbamate to be added was 0.9 parts; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

THIRD COMPARATIVE EXAMPLE

[0083] A fluororubber composition H was prepared in the same manner as First Embodiment, except that, in preparing the fluororubber composition, instead of the bismuth oxide, 3 parts of magnesium oxide (an acid acceptor, product name Kyowamag #150 made by Kyowa Chemical Industry Co., Ltd.) and 6 parts of calcium hydroxide (an acid acceptor, product name Caldic #1000 made by Ohmi Chemical Industry Co., Ltd.) were added; and a rubber laminate was prepared.

[0084] The results of the tests and evaluations are shown in Tables 1-3.

FOURTH COMPARATIVE EXAMPLE

[0085] A fluororubber composition I was prepared in the same manner as First Embodiment, except that, in preparing the fluororubber composition, the bismuth oxide was not added; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

FIFTH COMPARATIVE EXAMPLE

[0086] A fluororubber composition J was prepared in the same manner as First Embodiment, except that, in preparing the fluororubber composition, instead of the polyol-cross-linkable fluororubber, 100 parts of peroxide-cross-linkable fluororubber (product name Viton GF600S, made by Chemours Company) were mixed, the mixture of bisphenol AF and benzyltriphenyl phosphonium salt was not added, and 1.5 parts of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (product name Perhexa 25B-40, made by NOF Corporation) and 3 parts of triallyl isocyanurate (product name TRIC, made by Nihon Kasei Co., Ltd., TRIC being the registered trademark) were added in addition to the bismuth oxide; and a rubber laminate was prepared. The results of the tests and evaluations are shown in Tables 1-3.

TABLE-US-00001 TABLE 1 formulation acrylic rubber composition A B C D E carboxyl group-containing 100 100 100 acrylic rubber (1) containing ,-ethylenic unsaturated carboxylic acid having secondary alkyl ester carboxyl group-containing 100 acrylic rubber (2) containing ,-ethylenic unsaturated carboxylic acid having primary alkyl ester epoxy group-containing 100 acrylic rubber (3) carbon black 60 60 60 60 60 stearic acid 2 2 2 2 2 processing aid (lubricant) 1 1 1 1 1 antiaging agent 2 2 2 2 2 hexamethylene diamine 0.5 0.5 0.9 carbamate (aliphatic diamine) N,N-dicin-namylidene-1,6- 1.08 hexamethylene diamine (aliphatic diamine) 2,2-bis[4-(4- 1.28 aminophenoxy)phenyl]propane (aromatic diamine) guanidine cross-linking 2 2 2 2 2 accelerator

TABLE-US-00002 TABLE 2 formulation fluororubber composition F G H I J polyol-cross-linkable fluororubber 100 100 100 100 peroxide-cross-linkable fluororubber 100 carbon black 20 20 20 20 20 mixture of bisphenol AF 2.5 2.5 2.5 2.5 and benzyltriphenyl phosphonium salt bismuth oxide 10 10 hydrous bismuth nitrate oxide 15 magnesium oxide 3 calcium hydroxide 6 2,5-dimethyl-2,5-di(t- 1.5 butylperoxy)hexane triallyl isocyanurate 3

TABLE-US-00003 TABLE 3 acid resistance outer layer evaluation adhesion evaluation acrylic inner layer swelling to acidic peel percentage of acrylic rubber fluororubber aqueous solution of strength rubber left on surface of composition composition fluororubber (%) (N/mm) fluororubber (%) first A F 2.7 3.5 100 embodiment second B F 2.7 3.2 100 embodiment third C F 2.7 2.9 70 embodiment fourth A G 3.1 3.2 100 embodiment fifth B G 3.1 3.3 100 embodiment sixth C G 3.1 2.8 70 embodiment first D F 2.7 1.5 0 comparative example second E F 2.7 0.9 0 comparative example third A H 107 3.0 100 comparative example fourth A I comparative example fifth A J 5 2.0 30 comparative example

[0087] From Tables 1-3, rubber laminates each obtained from adhering through cross-linking an acrylic rubber layer (A) formed by adding an aliphatic polyvalent amine compound or a derivative thereof to a carboxyl group-containing acrylic rubber as a cross-linking agent and a fluororubber layer (B) formed by adding a bismuth oxide as an acid acceptor to a polyol-cross-linkable fluororubber were satisfactory in both acid resistance and adhesiveness

FIRST THROUGH SIXTH EMBODIMENTS

[0088] In contrast thereto, each of rubber laminates of acrylic rubber layers and fluororubber layers where either one of an acrylic rubber layer (A) formed by adding an aliphatic polyvalent amine compound or a derivative thereof to a carboxyl group-containing acrylic rubber as a cross-linking agent and a fluororubber layer (B) formed by adding a bismuth oxide as an acid acceptor to a polyol-cross-linkable fluororubber was not used was unsatisfactory in at least either one of acid resistance and adhesiveness (First through Fifth Comparative Examples).

[0089] Although the modes for carrying out the present invention have been described above, the present invention is not limited to specific modes for carrying out the present invention or embodiments; various modifications and changes can be made within the scope of the claimed invention.

[0090] The present international application claims priority to Japanese Patent Application No. 2017-69242 filed Mar. 30, 2017, the entire contents of which are hereby incorporated herein by reference.