JPH0366750A - Rubber composition for oil-resistant hose - Google Patents

Abstract

PURPOSE:To obtain a rubber composition for oil-resistant hose having excellent adhesivity to fluororubber and suitable as an outer layer of an inside layer of an inner fluororubber tube of an automobile fuel hose, etc., by compounding specific amounts of calcium carbonate, a substituted alkylthiourea compound, etc., to an epichlorohydrin rubber. CONSTITUTION:The objective composition can be produced by compounding (A) 100 pts.wt. of an epichlorohydrin rubber with (B) 0.5-30 pts.wt. (preferably 1-15 pts.wt.) of calcium carbonate, (C) 0.1-3 pts.wt. (preferably 0.2-2 pts.wt.) of a substituted alkylthiourea compound [e.g. 1,3-bis(dimethylaminopropyl)-2- thiourea] and (D) 0.1-10 pts.wt. (preferably 0.5-5 pts.wt. of an epoxy compound. As necessary, the composition is further compounded >=0.1 pts.wt. of an additional component comprising (E) 0-8 pts.wt. of a phenolic resin having a softening point of 60-130 deg.C and (F) 0-5 pts.wt. of 1,8-diazabicyclo(5,4,0)-undecene-7 or its weak acid salt.

Description

[Detailed description of the invention]

(Industrial Field of Application 1) The present invention relates to a rubber composition for oil-resistant hoses that has excellent adhesion to fluororubber, and more specifically for the inside of the fluororubber inner tube of oil-resistant rubber hoses for automobile fuel oil systems, lubricating oil systems, etc. The present invention relates to an epichlorohydrin-based rubber composition with excellent adhesive properties that is used as an outer layer.

[Conventional technology] Conventionally, oil-resistant rubber hoses used for this type of purpose in automobiles have generally had an inner tube rubber layer made of acrylonitrile butadiene rubber. However, in recent years in the automobile industry, due to social demands such as environmental pollution issues and economic efficiency, for example, in fuel oil rubber hoses, the inner tube rubber layer has become damaged due to the oxidation of the fuel oil due to high temperatures in the engine room and high pressure circulation. Rubber made of such materials can no longer be used because of its hardening deterioration, softening due to alcohol-mixed gasoline, and increased permeation into the atmosphere. Even in lubricating oil-based rubber hoses, it has been found that the porcelain tube rubber layer deteriorates significantly due to oxidative deterioration of the lubricating oil due to high temperatures and synthetic lubricating oils that have been rapidly used in recent years. Therefore, fluororubber has come to be used as an inner tube rubber material that has excellent oil resistance under such severe conditions. [Problem to be solved by the invention]

However, since fluororubber is expensive, various rubber hoses have been proposed in which the inner tube rubber layer has a double structure consisting of a thin inner layer made of fluororubber and an outer layer made of a low-cost rubber material. However, interlayer adhesion between fluororubber and other rubbers is difficult, and although many proposals have been made to improve their adhesion, they are still far from perfect. Kosho 55-168
No. 31, Japanese Patent Publication No. 55-2336, Japanese Patent Publication No. 55-515
No. 54, JP-A-54-158481, JP-A-57-4
9391, Japanese Patent Publication No. 59-35787, etc., the adhesion state is delamination even when pressure vulcanized using a molding press, and the adhesion strength further decreases in hose products, so it is difficult to put them into practical use. Ta. Also, JP-A-56-121762, JP-A-61-14
No. 0692, JP-A-61-244545, JP-A-62
-46641, JP-A-62-46642, JP-A-6
Proposals such as No. 1-16621 and Japanese Patent Publication No. 61-16622 require peroxide vulcanization of at least one layer, and even if the interlayer adhesion is sufficient, the vulcanization of oxygen and organic substances during vulcanization is In order to avoid sulfur inhibition, special measures such as coating the hose surface with lead or resin are required, resulting in increased costs. Therefore, in order to solve these problems, we developed a hose that has excellent adhesion between the inner tube rubber layer and the inner layer of fluorocarbon rubber, does not require peroxide vulcanization, and has various performances as an oil-resistant hose at a lower cost. There is a need for a satisfactory rubber composition for the outer layer. [gA Means and Effects for Solving the Problem 1] The present invention uses 0.5 to 30 parts by weight of calcium carbonate, 0.1 to 3 parts by weight of a substituted alkylthiourea compound, and 0.5 parts by weight of an epoxy compound to 100 parts by weight of epichlorohydrin rubber. This is a rubber composition for an oil-resistant hose that has excellent adhesion to fluororubber and contains 1 to 10 parts by weight as an essential component. Also,
0 to 8 parts by weight of a phenolic resin having a softening point of 60 to 130°C, and 0 to 5 parts by weight of 1,8-diazabicyclo(5,4,0)undecene-7 or its weak acid salt as combined components,
This is a composition for an oil-resistant hose that has excellent adhesion to fluororubber and is characterized by containing at least 0.1 part by weight of a concomitant component. The fluororubber to which the composition of the present invention is applied is a highly fluorinated rubber such as vinylidene fluoride-propylene hexafluoride copolymer or vinylidene fluoride-propylene hexafluoride-ethylene tetrafluoride terpolymer. Copolymer is used as raw material rubber, and vulcanizing agent and gold IA are added to it.
Auxiliary materials such as a compound are appropriately blended. As the vulcanizing agent, polyol vulcanizing agents such as aromatic polyol compounds are preferred. Next, the compounding composition used for the inner tube rubber outer layer, which is a feature of the present invention, will be explained in detail. First, epichlorohydrin-based rubbers include epichlorohydrin homopolymer, shrimp chlorohydrin-allyl glycidyl ether binary copolymer, shrimp chlorohydrin-ethylene oxide di-copolymer, and epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary copolymer. coalescence is used. These epichlorohydrin rubbers can be used alone or in combination.6 Next, the essential components and combined components used in the formulation in the present invention will be explained. Calcium carbonate, which is used as an essential component in this formulation, is used in an amount of 0.5 to 30 parts by weight, preferably 1 to 15 parts by weight, per 100 parts by weight of epichlorohydrin rubber. If it is less than this range, the adhesive strength will be poor, while if it exceeds this range, the mechanical properties of the vulcanizate will be impaired, which is not preferable. In this formulation, the substituted alkylthiourea compounds used as essential components include 1,3-bis(dimethylaminopropyl)-2-thiourea and l-dimethylaminopropyl-3, which have been conventionally used as antiozonants.
-Oxydiethylenethiourea and the like may be mentioned in particular. The amount used is 0.1 to 3 parts by weight, preferably 0.2 to 2 parts by weight, per 100 parts by weight of epichlorohydrin rubber. If it is less than this range, the adhesive strength will be poor, while if it exceeds this range, the vulcanization rate will increase and the tensile strength will deteriorate. The epoxy compounds used as essential components in this formulation include bisphenol A epoxy resin, resorcinol epoxy resin, tetrahydroxyphenylethane epoxy resin, novolak epoxy resin, glycidyl ether of ethylene oxide polymer or propion oxide polymer. type, glycidyl ether type of polyhydric alcohol, etc. The amount used is 0.1 to 10 parts by weight, preferably 0.5 to 5 parts by weight, per 100 parts by weight of rubber. If it exceeds this, the vulcanization rate will drop significantly, making it difficult to fully exhibit the physical properties of epichlorohydrin rubber. The three types of components detailed above are used as essential components. The phenolic resin used as a combined component in this formulation has a softening point of 60°C to 130°C and phenol,
Compounds obtained through the condensation reaction of phenolic compounds such as cresol, xylenol, alkylphenol, phenylphenol, and resorcinol with formaldehyde, acetaldehyde, paraformaldehyde, furfural, etc.
Modified products thereof such as terpenes and cashews are preferably used. Those with a softening point of less than 60°C have difficulty in workability during processing, while those with a softening point of 130°C or higher have difficulty in dispersibility and are undesirable.0 The amount of phenolic resin used is epichlorohydrin rubber. The amount is from 0 to 8 parts by weight, preferably from 0.1 to 5 parts by weight, per 100 parts by weight.If it is not added, sufficient adhesive strength cannot be obtained, and even if it exceeds 8 parts by weight, the effect of the present invention cannot be improved. is not particularly effective. 1,8-diazabicyclo(5,4,0)undecene-7 (hereinafter referred to as DBU) used as a concomitant component in this formulation
DBU-carbonate, DBU-stearate, DBU-stearate, DBU-carbonate, DBU-stearate,
BU-2 ethylhexyl salt, DBU-benzoate, DB
U-naphthoate, DBU-phenol salt, DBU-2
-Mercaptobenzothiazole salts and the like are preferably used. D.B.U. The amount of weak acid salt used in DBU is 1 for epichlorohydrin rubber.
0 to 5 parts by weight, preferably 0.1 to 0.00 parts by weight
It is 3 parts by weight, and sufficient adhesive strength cannot be obtained without adding it.
Moreover, if the amount exceeds 5 parts by weight, the vulcanization rate of the epichlorohydrin rubber becomes too fast, causing processing difficulties. All of these combined components are added for the purpose of improving adhesive strength. The minimum amount of these combined components added is 0.1 part by weight. Phenol resin alone or DBU, DBU
Although it is recognized that the weak acid salt alone significantly improves the adhesive strength, by using both together, the adhesive strength of the - layer can be improved.In the present invention, the essential components and the combined components are used as described above. Ru. As the vulcanizing agent used in this formulation, all vulcanizing agents used for epichlorohydrin rubber can be used. For example, there are sulfur-based vulcanizing agents that utilize the unsaturated bonds of allyl glycidyl ether, diamine-based vulcanizing agents that utilize chlorine in rubber, polythiols, thioureas, etc. Among them, thioureas, For example, the use of 2-mercaptoimidacillin is particularly preferred in terms of the balance between vulcanization rate and vulcanization physical properties.The amount of these vulcanizing agents added is 0.2 to 10 parts by weight per 100 parts by weight of epichlorohydrin rubber. A range of is appropriate. Further, a peroxide-based vulcanizing agent can also be used in combination with the above-mentioned vulcanizing agent. This formulation also contains vulcanization accelerators, vulcanization retarders, acid acceptors, reinforcing agents, fillers, and plasticizers as necessary. Compounding agents commonly used in this technical field can be added, such as lubricants, anti-aging agents, pigments, and refueling agents. In particular, the addition of a metal compound as an acid acceptor is particularly effective from the viewpoints of tight vulcanization, foaming prevention, and thermal stability of the present formulation. These metal compounds include magnesia, magnesium hydroxide, barium hydroxide, magnesium carbonate, barium carbonate, quicklime, calcium hydroxide, calcium silicate, calcium stearate, zinc stearate, calcium phthalate,
Magnesium phosphite, calcium phosphite, zinc white,
tin oxide, litharge, red lead, white lead, dibasic lead phthalate,
Dibasic lead carbonate, tin stearate, basic lead sulfite,
Examples include basic sulfite buttons. Its blending amount is 0.5 parts by weight per 100 parts by weight of epichlorohydrin rubber.
A range of 20 parts by weight is preferred. However, when quicklime, calcium hydroxide, magnesia, etc. do not absorb moisture, good physical properties can be obtained and they can be substituted for calcium carbonate in the present invention. This causes variation. Therefore, in the present invention, the use of these acid acceptors is limited. As described above, it has been found that by using a composition comprising these polar group-containing rubber formulations, the interlayer adhesive strength with fluororubber can be significantly improved. For the outer tube rubber layer, known epichlorohydrin rubber containing chlorine groups, chlorosulfonated polyethylene, chloroprene rubber, etc. can be used, but a copolymer of epichlorohydrin, ethylene oxide, and acrylic glycidyl ether has excellent weather resistance, and this rubber The triazine vulcanization system has excellent compression set and is more preferred. The composition of the present invention and the fluororubber can be bonded together by laminating them and vulcanizing them in the same way, or by molding one in a semi-vulcanized state, then laminating them and fully vulcanizing them. can. That is, in the hose molding method, two inner tube rubber layers, an inner layer made of fluororubber and an outer layer made of epichlorohydrin rubber, are simultaneously extruded,
First, the inner layer of fluororubber is extruded onto a flexible mandrel and formed into a semi-vulcanized state, and then the outer layer of epichlorohydrin rubber is placed on top of it! It can be molded by extruding layer A and sufficiently vulcanizing and adhering both layers.

【Example】

Hereinafter, the present invention will be explained in detail based on examples. Examples 1 to 5 Comparative Examples 1 to 3 Oil-resistant rubber hoses having the structure shown in FIG. 1 were manufactured by the method shown below. The fluororubber unvulcanized composition having the formulation shown in Table 2 is used as the inner tube rubber layer (1), and the epichlorohydrin rubber unvulcanized composition having the formulation shown in Table 1 is used as the inner tube rubber outer layer (2). So, Table 2, Part name: Viton E-430 (DuPont) Product name: Daiel G-555 (Daikin M) Product name:
Ebichroma-C (Da(So&g)) Product name: Parnok R (Dai 1'liM Kagakusha I) Phenol Nermaldehyde Igi, Norlac base, Softening point 95℃ Phenol formaldehyde! San, Resol type, @ Softening point 65℃ drunken name;
Ebicoat 828 (Bisphenol AW Emexy 1!,
Shell Oil IT Science) Product 62 Nokura Guku NS-1ON
(Iriuchi Ill stop 7 shocks) A * mark indicates rubber failure, and no mark indicates interfacial peeling on the adhesive surface. Extrusion molding was performed using a double extruder so that the combinations were as shown in Table 3. The inner diameter of this inner rubber hose is 7.
5nn, wall thickness is 2.0m, of which the inner layer thickness is approximately 0.
．． It was 5m++. This inner tube rubber hose is knitted with reinforcing yarn (WIC3) made of polyester fibers by braiding at a braid angle of 52°, and an epichlorohydrin rubber unvulcanized composition having the composition shown in Table 1, Example 4 is placed on the outside. Tube rubber layer (
4) Extrusion coating was performed. A metal mandrel having an outer diameter of 7.5 m was inserted into this unvulcanized rubber hose using compressed air. After insertion, the reinforcing thread waste (3) became almost at a rest angle. After vulcanizing this by direct steam vulcanization at 6 kgf/cd for 20 minutes, the metal mandrel was pulled out, and the desired oil-resistant hose was obtained by cleaning and heat treatment. Product peeling test A sample of the reinforced hose product obtained by the above manufacturing method was
Cut it to length, make a radial cut along the axis to expose the fluororubber inner tube inner layer (1), and combine this fluororubber inner tube inner layer (1) with the epichlorohydrin-based rubber inner tube outer layer of the present invention. (2) was peeled off by about 90° to prepare a test sample. Then, this test sample was attached to a product peeling test jig in the state shown in Figure 2, and heated at 25°C.
A peel test was conducted at a tensile speed of 0.01 m/win. The test was conducted on untreated and fuel oil C (isooctane/I~luene = 50150vo1%) immersion at 40°C x 48[(
The results are shown in Table 3. As is clear from the results in Table 3, the reinforced hose product samples using the composition of the present invention exhibited rubber failure even when untreated or after being immersed in hot fuel oil, and no peeling occurred at the interface. In contrast, Comparative Example 1. lacks calcium carbonate, which is an essential component in the composition of the present invention. Essential ingredients 1 and 3
Comparative Example 2, which lacks -bis(dimethylaminopropyl)-2-thiourea, and Comparative Example 3, which lacks the essential epoxy resin, both had low peel strength on the adhesive surface when untreated and after immersion in hot fuel oil. Interfacial delamination is occurring.

【Effect of the invention】

As detailed above, by using the rubber composition for oil-resistant hoses (epichlorohydrin rubber) of the present invention as the outer layer of the inner tube, the interlayer adhesive strength with the inner layer of the fluororubber inner tube was significantly improved. Therefore, the liquid-contacting part of the inner tube rubber inner layer is made of fluororubber, which has excellent physical properties, so it can withstand harsh usage conditions such as when sour gasoline is used, and the outer tube rubber inner layer contacting the outside air has excellent heat resistance, weather resistance, Since it is an epichlorohydrin rubber with excellent gasoline resistance, it also meets the requirements for heat resistance and maintenance-free operation. With such a configuration, it is suitable for automobile fuel hoses, especially EG.
It is extremely effective for applications such as f (electric, gasoline, injection) hoses.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an oil-resistant rubber hose according to the present invention in a direction perpendicular to its axis. FIG. 2 is a perspective view of the product peel test jig. (1) Inner tube rubber inner layer (2) Inner tube rubber outer layer (
3) Reinforcing thread layer (4) Outer tube Pum calendar and above Figure 1 Figure 2

Claims (1)

[Scope of Claims] 1. 0.5 to 30 parts by weight of calcium carbonate, 0.1 to 3 parts by weight of a substituted alkylthiourea compound, and 0.1 to 3 parts by weight of an epoxy compound based on 100 parts by weight of epichlorohydrin rubber.
A rubber composition for an oil-resistant hose, characterized in that it contains 10 parts by weight as an essential component. 2. The rubber composition according to claim 1, which has a softening point of 60
0 to 8 parts by weight of a phenolic resin at ~130°C, and 1,
1. A rubber composition for an oil-resistant hose, comprising at least 0.1 parts by weight of 8-diazabicyclo(5,4,0)undecene-7 or a weak acid salt thereof as a concomitant component.