JP2005146097A - Rubber composition, rubber hose and high-pressure hose each using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an economically advantageous rubber composition excellent in water-barrier tendency, oil resistance and mechanical properties and good in workability. <P>SOLUTION: The rubber composition comprises a polymer and a layer mineral filler dispersed in the polymer; wherein the polymer contains ≥70 mass% of a nitrile rubber(NBR) and the layer mineral filler is hydrophobic, subjected to no organized surface treatment and contained at ≥80 mass% in the polymer. Rubber hoses and high-pressure hoses each using this rubber composition are also provided, respectively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a rubber composition useful for producing gaskets, packing materials, tires, tire tubes, and the like, and a rubber hose and a high-pressure hose using the rubber composition, and more particularly to a high-pressure hose for an operating system.

  High-pressure hoses are used for cleaning systems with high-pressure water and operating systems in various fields such as machine tools, construction machines, and automobiles. The high-pressure hose used in such an operating system is generally a wire blade (W / B) hose, and is roughly divided into a mineral system and a water system. W / B hose materials used in hydraulic systems that use mineral oils are required to have oil resistance. Nitrile rubber (NBR) is generally used in environments up to a temperature of about 120 ° C. (eg, In Patent Document 1), hydrogenated NBR (H-NBR) is used when a higher operating temperature environment is required, such as power steering oil for trucks.

  However, in disaster countermeasures such as fire and recycling applications, the use of mineral oils as working oils is avoided, and water systems such as water / glycol and phosphate esters are used. Similarly, there is a use of a high-pressure washing hose using an aqueous system. However, NBR used in mineral oils cannot be used because it has a problem of high moisture permeation and deteriorates the metal wire as the reinforcing layer. For this reason, ethylene propylene rubber (EPR, EPDM, EPT, etc.) is generally used for this application.

  For this reason, the working system hose is properly used in each of the mineral system and the water system, and an operating hose that can be used for both the mineral system and the water system has not yet been obtained. However, the market demand for such a combined hose is high.

JP 2001-289370 A

  Accordingly, an object of the present invention is to provide a high pressure hose excellent in oil resistance and water resistance, particularly a high pressure hose for an operating system.

  Moreover, this invention is providing the rubber hose excellent in water resistance and oil resistance.

  Furthermore, it is providing the rubber composition excellent in water barrier property (water resistance) and mineral oil barrier property (oil resistance) used advantageously for preparation of the said high pressure hose and rubber hose.

  Another object of the present invention is to provide a rubber composition that is excellent in water barrier property (water resistance) and mineral oil barrier property (oil resistance), has good workability, and is economically advantageous.

  The present inventors have studied to obtain a polymer composition having high water barrier property (low moisture permeability) and oil resistance that leads to good water resistance using a layered mineral filler. Among them, when a rubber composition is obtained by kneading an ordinary layered mineral filler that is hydrophobic and not treated with an organic surface using a specific type of rubber, by using a large amount of the layered mineral filler The present inventors have found that a low water permeability is obtained in spite of good workability, and that there is almost no deterioration of the properties specific to rubber. Also, the increase in viscosity due to the increase in the amount of layered mineral filler was small.

  Accordingly, the present invention is a rubber composition comprising a polymer and a lamellar mineral filler dispersed in the polymer, wherein the polymer contains nitrile rubber (NBR) by 70% or more by mass, and the lamellar mineral filler is hydrophobic. In addition, the rubber composition is characterized in that it is not subjected to an organic surface treatment and is further contained in an amount of 80% by mass or more based on the polymer.

  The hydrophobicity in the present invention is defined as follows. That is, 2 g of filler is added in 10 portions to a graduated cylinder containing 100 ml of water of pH 7.0 / 25 ° C. At this time, after the filler added earlier is deposited, the next filler is added. After leaving it for 24 hours, the apparent volume of the bottom of the vessel is measured, and those of 10 ml or less are made hydrophobic.

  In the rubber composition, it is preferable that NBR contains 25% by mass or more (further a range of 25 to 40% by mass, particularly a range of 30 to 40% by mass) of an acrylonitrile repeating unit. The rubber composition thus obtained has sufficient oil resistance and does not impair the rubber physical properties (rubber elasticity, etc.). Further, 100% by mass of the polymer is preferably nitrile rubber (NBR).

  The layered mineral filler is contained in an amount of 80% by mass or more (further in the range of 80 to 200% by mass, particularly in the range of 100 to 150% by mass) with respect to the polymer. Thereby, low gas shielding properties and low moisture permeability are obtained. In the composition of the present invention, even when a large amount of layered mineral filler is used, the rubber properties of the rubber composition are hardly deteriorated. The layered mineral filler is preferably at least one selected from mica, clay and talc.

  The present invention also resides in a crosslinked polymer composition obtained by crosslinking the rubber composition.

  The present invention also provides a rubber hose formed from the above rubber composition.

Furthermore, the present invention includes a high-pressure hose comprising a tubular rubber layer formed from the rubber composition described above; and a tubular inner rubber layer, a tubular metal wire reinforcing layer provided around the tubular rubber layer, and In a high-pressure hose (especially a high-pressure hose for an operating system) including a tubular outer rubber layer provided around it,
There is also a high-pressure hose characterized in that at least the inner rubber layer is formed from the above rubber composition.

  The rubber hose and high-pressure hose of the present invention include preferred embodiments of the rubber composition described above.

  In the rubber composition of the present invention, a hydrophobic and non-surface treatment type layered mineral filler that is not subjected to organic treatment is appropriately dispersed in a large amount in a polymer mainly composed of nitrile rubber. Thereby, oil resistance (mainly due to nitrile rubber) and low moisture permeability (mainly due to layered mineral filler) are compatible. Moreover, the rubber composition of the present invention has such excellent characteristics, but hardly deteriorates the original characteristics of rubber (mechanical characteristics such as elasticity). Furthermore, the rubber composition of the present invention can be obtained by simply kneading a nitrile rubber and a non-surface treatment type layered mineral filler, so that it is economical, and productivity is also improved.

  Therefore, it can be said that the rubber composition of the present invention has low moisture permeability, excellent mechanical properties inherent to rubber, good workability, and is economically advantageous. For this reason, the rubber composition of the present invention is particularly suitable for use in rubber hoses and high-pressure hoses that have both oil resistance and low moisture permeability.

  The rubber composition of the present invention has a basic structure in which a hydrophobic and non-surface treatment type layered mineral filler is appropriately dispersed in a large amount in a polymer.

  In the polymer composition of the present invention, it is considered that the layered mineral filler that is hydrophobic and not subjected to the organic surface treatment is oriented in a substantially parallel relationship with each other in the polymer mainly composed of nitrile rubber. Since it is considered that the mineral filler is dispersed in a relatively large particle shape (generally 4 to 7 μm), there is almost no decrease in the mechanical properties (eg, tensile stress, tensile strength, tensile elongation) of the rubber. In addition, since the layered mineral filler can be used in a relatively large amount as described above, the water permeability can be greatly reduced, and the NBR itself has oil resistance. It has excellent moisture permeability (water resistance) and oil resistance, and is suitable for rubber hoses and high pressure hoses for such applications.

  The rubber composition of the present invention generally has a polymer (mainly block-like NBR) and a non-surface treatment type layered mineral filler, etc., at a temperature of about 80 to 150 ° C. using a normal kneader such as an internal mixer such as Banbury. When a crosslinking agent is further added to this, a crosslinked rubber composition is obtained.

  Non-surface treatment used in the present invention, i.e., layered mineral filler that has not been subjected to organic surface treatment, may include clay, mica, kaolin clay, talc, etc. that have not been subjected to organic surface treatment, Among them, clay and mica having a flat shape are preferable. The average particle diameter of the layered mineral filler is 20 μm or less, more preferably in the range of 0.1 to 15 μm, particularly preferably 1.0 to 8.0 μm.

The clay is generally a fine particle having an average particle diameter of 20 μm or less, further 0.1 to 15 μm, particularly 0.1 to 8 μm, made of one or more clay minerals. The clay mineral is a fine layered silicate, and a layer formed by a tetrahedron in which Si ⁴⁺ ions are tetracoordinated to oxide ions (O ²⁻ ), Al ³⁺ , Fe ²⁺ , Fe ^3+. , Mg ^{2+, and the} like and octahedral layers having 6 coordination with O ²⁻ and hydroxide ions (OH ⁻ ) are combined at 1: 1 or 2: 1, and they are stacked to form a layered structure. What constitutes is generally. Examples of the clay mineral include kaolinite, halloysite, montmorillonite, zeolite, vermiculite and the like.

Mica (mica) is an orthorhombic layered silicate characterized by complete basal cleavage, and is a complex potassium aluminosilicate, the general chemical composition of which is XY _2-3 Zn ₄ O ₁₀ (OH, F). ₂ [However, X represents Ba, Ca, (H ₃ O), K, Na, (NH ₄ ), Y represents Al, Cr ³⁺ , Fe ²⁺ , Fe ³⁺ , Li, Mg, Mn ²⁺ , V ³⁺ Z represents Al, Be, Fe, Si]. The average particle size of mica is preferably 20 μm or less, more preferably 0.1 to 15 μm, and particularly preferably 1.0 to 8.0 μm.

Talc is magnesium silicate and is generally represented by Mg ₂ Si ₄ O ₁₀ (OH) ₂ .

  The amount of the layered mineral filler added is preferably 80% by mass or more, more preferably 80 to 200% by mass, and particularly preferably 100 to 150% by mass with respect to the polymer. When the amount of the filler is less than 80% by mass, the effect of moisture barrier property, that is, low moisture permeability (water resistance) cannot be sufficiently obtained, which is not preferable. Excessive addition may impair rubber properties.

  In addition to the layered mineral filler, other inorganic fillers may be used. Examples thereof include kaolin, calcium carbonate, and silica.

  In the polymer used in the present invention, nitrile rubber (NBR; acrylonitrile butadiene rubber) accounts for at least 70% by mass of the polymer. It is preferable to occupy 90 to 100% by mass, particularly 100% by mass. NBR preferably contains acrylonitrile repeating units in the range of 25% by mass or more and 25-40% by mass, particularly 30-40% by mass. This makes it possible to achieve both excellent oil resistance and low moisture permeability (water resistance) of the composition obtained.

  In the rubber composition of the present invention, a hydrophobic and non-organic surface treatment layered mineral filler (generally hydrophobic) is dispersed in NBR with an appropriate particle size, resulting in a significant increase in viscosity. Therefore, it is considered that a large amount of filler can be dispersed, and it can also have a low moisture permeability (water resistance) while maintaining the characteristic properties of rubber. The average particle diameter of the layered mineral filler in a dispersed state in the rubber composition of the present invention is considered to be 4 to 7 μm.

  Other polymers that can be used in addition to NBR are generally rubber (rubber or rubber latex). Examples thereof include natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), and isoprene rubber. Chloroprene rubber, butyl rubber (IIR), halogenated butyl rubber, ethylene-propylene rubber, acrylic rubber, chlorosulfonated polyethylene rubber, fluororubber latex, silicone rubber latex, urethane rubber latex. These can be used alone or as a mixture.

  As the polymer of the present invention, a normal thermoplastic resin other than the rubber may be used, or the rubber and a thermoplastic resin may be used in combination.

  As a crosslinking agent for performing crosslinking (vulcanization), various commercially available compounds can be used.

  Sulfur-based vulcanizing agents include powdered sulfur, highly dispersible sulfur, insoluble sulfur, etc., sulfur commonly used as rubber vulcanizing agents, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethyl Thiurams such as thiuram monosulfide, dipentamethylene thiuram tetrasulfide, pipemidine dipentadiene dicarbamate, pipecolyl dithiocarbamate, pipecoline, dimethyldithiocarbamate, zinc diethyldithiocarbamate, zinc dibutyldithiocarbamate, N-ethyl-N -Zinc phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, zinc dibenzyldithiocarbamate, sodium dimethyldithiocarbamate, diethyldithiocarbamate Dithiocarbamates such as sodium phosphate, sodium dibutyldithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, tellurium diethyldithiocarbamate, xanthates such as zinc butylxanthate, zinc isopropylxanthate, sodium isopropylxanthate N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N, N-diisopropyl-2-benzothiazole Examples thereof include sulfenamides such as sulfenamide, and thiazoles such as 2-mercaptobenzothiazole and dibenzothiazyl disulfide.

  Further, as vulcanization accelerators, thiurams such as TMTD (tetramethyl disulfide) and dithiocarbamates such as EZ (zinc diethyldithiocarbamate) can be used.

  The amount of the crosslinking agent used is preferably 0.5 to 4.0% by mass, particularly 1.0 to 2.5% by mass, based on the polymer (generally NBR).

  Examples of the organic peroxide include hydrogen peroxide solution, cumene hydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di- (t- Butylperoxy) hexane, 1,3-bis (t-butylperoxyisopropyl) benzene, n-butyl-4,4-bis (t-butylperoxy) valerate, 1,1-bis (t-butylperoxy) -3, 3,5-trimethylcyclohexane, 2,2-bis (t-butylperoxy) butane, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzene, vinyl tris (t-butylperoxy) Silane or the like can be used. Dicumyl peroxide is preferred. The amount used is preferably 0.2 to 8.0% by mass, particularly 0.25 to 4.0% by mass, and more preferably 0.3 to 2.0% by mass with respect to the polymer (generally NBR).

  Further, as the vulcanization accelerator, thiurams such as TMTD (tetramethyl disulfide) and dithiocarbamates such as EZ (diethyldithiocarbamine-producing zinc) can be used.

  Furthermore, in combination with these, organic peroxides, quinonedioximes, polyfunctional acrylic monomers {eg, trimethylolethane triacrylate (TMETA), trimethylolpropane triacrylate (TMPTA), dipentaerythritol ether hexaacrylate (DPEHA) ), Pentaerythritol tetraacrylate (DPEHA), dimethylolpropane diacrylate (TMPTA), stearyl acrylate (SA)}, and triazine thiol.

  The amount of the crosslinking agent used is preferably 0.05 to 5.0% by mass, particularly preferably 0.1 to 4.0% by mass, based on the polymer (generally NBR).

  The amount of the organic peroxide used is 0.1 to 1.0% by mass, particularly 0.1 to 0.8% by mass, and more preferably 0.3 to 0.5% by mass with respect to the polymer (generally NBR). preferable.

  Next, the manufacturing method of the rubber composition of this invention is demonstrated.

  The layered mineral filler and the raw rubber are put into a general-purpose kneader such as a Banbury mixer. The temperature during the kneading is preferably set to a temperature at which the layered mineral filler can be dispersed in the rubber, and is generally 50 to 180 ° C, preferably 80 to 150 ° C. The kneading time may be a time during which the layered mineral filler can be dispersed in the rubber, and is generally 5 to 15 minutes. A rubber composition is obtained by kneading under such conditions. An appropriate crosslinking agent and / or crosslinking accelerator is added to this rubber composition using a Banbury mixer and the like is crosslinked under suitable conditions to obtain a crosslinked rubber composition.

  The rubber hose of the present invention can be obtained by forming into a tubular shape by a known method using the rubber composition of the present invention.

  Moreover, about the high pressure hose of this invention, one example of the typical structure is shown in FIG. A tubular inner rubber layer 11, a wire reinforcing layer 12a wound on the surface in a spiral shape, a tubular intermediate rubber layer 13 covering the surface, a wire reinforcing layer 12b wound on the surface in a spiral shape, and the surface It is comprised from the tubular outer side rubber layer 14 to cover. A high pressure hose with a five-layer structure. The inner rubber layer 11 is formed from a rubber composition in which a layered mineral filler of a type that has not been subjected to an organic surface treatment is dispersed in an NBR-containing polymer. The intermediate rubber layer 13 may also be formed from the same rubber composition as the inner rubber layer 11, but may be another composition.

  Another example of a typical structure of the high-pressure hose of the present invention is shown in FIG. A tubular inner rubber layer 21, a wire reinforcing layer 22 whose surface is wound in a blade structure, and a tubular outer rubber layer 24 covering the surface are formed. A high pressure hose with a three-layer structure. The inner rubber layer 21 is formed from a rubber composition in which a layered mineral filler of a hydrophobic type that is not treated with an organic surface is dispersed in an NBR-containing polymer.

  The inner rubber layers 11 and 21 have a function of suppressing transmission of volatile components such as mineral oil and water to be pumped.

  The tubular wire reinforcement layers 12 and 22 are generally metal fiber spiral or braided structures. Examples of the metal fiber include soft wire, yarn, hard steel wire, and stainless steel. The steel wire may be subjected to appropriate plating such as brass plating or zinc plating. Those obtained by knitting these metal fibers into a spiral shape or a blade shape are preferable. The thickness (diameter) of these fibers is generally in the range of 0.15 to 1.0 μm.

  The rubber composition forming the inner rubber layer and the like of the present invention is a layered mineral filler that is hydrophobic and not treated with an organic surface, because a large amount of the layered mineral filler is dispersed in the NBR-containing polymer. Is further suppressed. Therefore, the permeation of water vapor is suppressed, and the corrosion of the metal wire is suppressed. As a result, the water resistance is improved. The high-pressure hose containing the rubber composition is applicable to this aqueous system because it maintains oil resistance and hardly corrodes the wire even in the aqueous operation system.

  Hereinafter, the present invention will be described in detail by way of examples. The present invention is not limited to the examples.

[I] The materials used are as follows.
(A) Polymer A1: NBR (acrylonitrile-butadiene rubber),
N230 (acrylonitrile repeating unit content: 35% by mass), manufactured by JSR Corporation
(B) Layered mineral filler B1: Hydrophobic non-organized clay, manufactured by Nippon Mystron Co., Ltd., Mistron Paper B2: Hydrophobic non-organized mica, manufactured by Co-op Chemical Co., Ltd.
B3: Hydrophobic organic mica, manufactured by Co-op Chemical Co., Ltd., Somasif MEE
B4: hydrophilic non-organized natural montmorillonite clay, manufactured by Kunimine Industry Co., Ltd.
Kunipia F
(C) Other materials C1: FEF carbon black C2: Plasticizer (ether ester plasticizer)
C3: Sulfur C4: Accelerator CZ
C5: Accelerator TT
C6: Stearic acid C7: Zinc oxide

[II] Sample Preparation Method Samples and high-pressure hose preparation methods are shown in the following examples and comparative examples.

[Examples 1-2, Comparative Examples 1-3]
(1) Production of rubber composition and sheet Kneaded the (A) polymer, (B) layered mineral filler, and (C) other materials with the indicated mass at 100 ° C. using a Banbury mixer. Obtained.
(2) Production of high-pressure hose The inner rubber layer was formed by extruding the obtained rubber composition using an extruder. The obtained tubular inner rubber layer had a thickness of 2.0 mm.

  Next, a total of 40 wires (diameter 0.35 mm) were wound as reinforcing layers on the obtained tube-shaped inner rubber layer to form a wire reinforcing layer wound around a blade structure.

  An outer rubber layer was extrusion coated on the outer periphery of the reinforcing layer (thickness 1.2 mm).

  A high-pressure hose was manufactured as described above. The obtained hose had an inner diameter of 11.0 mm and an outer diameter of 19.0 mm.

[III] Evaluation method 1) Evaluation of flexibility and workability of rubber composition An evaluation was performed by the worker during the work of manufacturing a high-pressure hose using the rubber composition.
2) Moisture shielding property A stainless steel tube (inner diameter: 2 cm) is filled with water and covered with the above vulcanized rubber sheet having a thickness of 1 mm. This was put into an oven at 100 ° C., the weight was measured every 24 hours, and the amount of moisture permeation was measured.
3) Evaluation of durability (thermal aging property) of high-pressure hose Water was pressurized and sealed at 30 MPa as an aqueous medium in the obtained high-pressure hose and stored in an oven at 80 ° C. for 500 hours. Thereafter, the burst pressure measurement of the hose and the corrosion state of the wire were visually observed.
3) Durability (heat aging property) evaluation of high-pressure hose The evaluation results are shown in Table 1 below.

  As described above, since the rubber sheet and the high-pressure hose obtained in the examples of the present invention are excellent in moisture barrier properties, the high-pressure hose hardly generates rust and has a low burst pressure reduction rate. The rubber sheet and the high-pressure hose of Comparative Example 1 using expensive organically treated surface-treated mica are comparable. However, when the organic surface-treated mica of Comparative Example 1 was used, workability and rubber flexibility were greatly reduced due to the large amount of use. Comparative Example 2 using a hydrophilic filler and Comparative Example 3 using no filler are quite inferior characteristics.

It is a perspective view of one example of the typical structure of the high-pressure hose of the present invention. It is a perspective view of another example of the typical structure of the high pressure hose of this invention.

Explanation of symbols

11, 21 Tubular inner rubber layer 12a, 12b, 22 Reinforcing layer 13 Tubular intermediate rubber layer 14, 24 Outer rubber layer

Claims (8)

  A rubber composition comprising a polymer and a layered mineral filler dispersed in the polymer, wherein the polymer contains 70% or more of nitrile rubber (NBR) by mass, and the layered mineral filler is hydrophobic and organically treated A rubber composition characterized by containing 80% by mass or more based on the polymer.   The rubber composition according to claim 1, wherein the layered mineral filler is contained in the range of 80 to 200 mass% with respect to the polymer.   The rubber composition according to claim 1 or 2, wherein NBR contains acrylonitrile repeating units in a range of 25 to 40% by mass.   The polymer composition according to any one of claims 1 to 3, wherein the layered mineral filler is at least one selected from mica, clay and talc.   A crosslinked polymer composition obtained by crosslinking the rubber composition according to claim 1.   A rubber hose formed from the rubber composition according to claim 1.   A high-pressure hose comprising a tubular rubber layer formed from the rubber composition according to claim 1. In a high-pressure hose including a tubular inner rubber layer, a tubular metal wire reinforcing layer provided around the tubular rubber layer, and a tubular outer rubber layer provided around the tubular rubber layer,
A high-pressure hose characterized in that at least the inner rubber layer is formed from the rubber composition according to any one of claims 1 to 7.

Images