JPH09157404A - Synthetic fiber-reinforced rubber composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition, comprising specific synthetic fibers having a coating layer on the surfaces thereof and a rubber compound, improved in adhesion and useful as a tire, etc., without easily peeling even when a great shearing force is produced. SOLUTION: This rubber composition comprises (A) synthetic fibers having (i) a coating layer of at least one of a metallic oxide, a metallic oxyhydroxide and a metallic hydroxide (e.g. β-FeOOH) on the surface and further (ii) sulfur or a sulfur-containing compound, bonded or fixed thereto and (B) a rubber compound. Furthermore, the component (A) is at least any one of aromatic polyamide fibers, aliphatic polyamide fibers, polyester fibers, rayon, carbon fibers, polypropylene fibers, polyethylene fibers, acrylic fibers, polyvinyl alcohol- based fibers and polyurethane fibers and a metal of the component (i) is preferably Fe, Cr, Mn, etc. For example, the fibers are preferably immersed in a 0.001-30% suspension of the component (i) having 0.1-1000Å particle diameter at a controlled pH and temperature to form the coating layer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rubber composition reinforced with synthetic fibers used for tires, transmission belts, conveyor belts, hoses and the like.

[0002]

2. Description of the Related Art Generally, industrial rubber products such as tires, transmission belts, conveyor belts, hoses and rubberized cloth are reinforced with synthetic fibers. Synthetic fibers such as rayon, aliphatic polyamide fiber polyester fiber, cotton, wool,
Compared with natural fibers such as hemp, it generally has superior properties such as high strength, high elastic modulus, good heat resistance, excellent resistance to friction, and good dimensional stability due to water and heat. Therefore, it is widely used as a reinforcing fiber. recent years,
In the automobile industry etc., steel fibers are used to reinforce rubber due to increasing demands for higher strength and higher elastic modulus due to exhaust gas countermeasures, noise reduction measures, belts that can withstand high temperature use, and radial tires. However, due to the difference in the coefficient of thermal expansion with rubber, it tends to peel off from rubber when used at high temperatures, and has the disadvantage that it has a high specific gravity and makes the product heavy, and synthetic fibers have come to the forefront. Came.

Conventionally, in order to bond a synthetic fiber and a rubber compound, a so-called resorcin-formalin resin-rubber latex (hereinafter, referred to as RFL) containing a resorcin-formalin resin and a rubber latex as main components is used as an adhesive. The method used is widely known, and according to this method, a certain degree of adhesive force can be obtained between the synthetic fiber and the rubber compound. For example, Japanese Unexamined Patent Publication (Kokai) No. 49-96048 proposes a method for adhering polyamide fiber and chloroprene rubber using an RFL obtained by mixing chlorohydrin rubber latex and chloroprene latex with a resorcin-formalin resin. There is. JP 59
JP-89375 proposes a method of adhering rubber to fibers using RFL composed of chloroprene-dichlorobutadiene copolymer latex and resorcin-formalin resin.

[0004]

However, the RFL
The fiber-reinforced rubber composition produced by using
When used in applications where large shearing occurs between the fiber and rubber due to dynamic external force such as bending, compression, and elongation, the adhesive strength is insufficient, and as a result, even when the fiber is an aromatic polyamide, Delamination failure occurs at the interface. Further, even when the fiber is rayon, aliphatic polyamide fiber, polyester fiber, etc., it is required that it can be used under more severe conditions. That is, from the viewpoint of durability and stability, there is a strong demand for improvement in the adhesiveness between the synthetic fiber and the rubber compound in order to meet the above requirements.

The object of the present invention is to provide a rubber composition reinforced with a fiber, which does not easily peel off even if a large shearing force is generated between the fiber and the rubber having improved adhesion between the reinforcing fiber and the rubber compound. The present invention provides a rubber composition.

[0006]

The present invention has been completed to achieve the above-mentioned object, and a metal oxide on the surface,
Metal oxyhydroxide, having at least one coating layer of metal hydroxide, and further comprising sulfur or a compound containing sulfur, a synthetic fiber and a rubber compound whose surface is activated by bonding or fixing. Provided is a rubber composition having improved adhesion between fibers and a rubber compound. Hereinafter, the present invention will be described in more detail.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The metal of "metal oxide, metal oxyhydroxide, metal hydroxide" in the present invention means 2 or 3
Valent Fe, Cr, Mn, Cu, Co, Ni, V, Al,
It refers to Si, Ti, Ga, or the like. In the composition of the present invention, the surface of the synthetic fiber has at least one coating layer of a metal oxide, a metal oxyoxide or a metal hydroxide.

This coating layer is prepared by adding fibers to a 0.001% to 30% suspension of metal oxides, metal oxyhydroxides, metal hydroxides having a particle size of 0.1Å to 1000Å, which has been subjected to pH and temperature control. By immersing, metal oxide,
Metal oxyhydroxide and metal hydroxide adhere to the fiber to form. The smaller the particle size of the oxide, the oxyhydroxide, and the hydroxide, the better the interfiber dispersion and the less coating defects,
The larger the value, the greater the amount of adhesion. As the metal oxide, the metal oxyhydroxide, and the metal hydroxide, commercially available products may be used, but fine fibers such as tows, staples, filaments, and other fibers and woven cloth are evenly used for individual fibers. As a method for coating without defects, metal fibers, metal oxyhydroxides, metal oxyhydroxides, metal oxides, metal oxyhydroxides are prepared by immersing the fibers in an aqueous solution of a compound for producing metal hydroxides, and then adjusting pH and adding energy. , It is desirable to form metal hydroxides and attach them to fibers. The optimum coating amount varies depending on the type, form, and application of the fiber, but the weight ratio to the fiber is 1: 0.000.
1 to 0.2 is suitable.

For example, when FeCl ₃ is used as a compound for forming a metal oxyhydroxide and the solution is heated to 50 to 70 ° C. and alkali is added with sufficient stirring, <pH
Under the condition of 2.5, β-FeOOH is produced. pH adjustment,
Energy addition condition is different from metal, but usually pH
1-13, temperature Room temperature-100 degreeC. pH, temperature,
By controlling the metal salt concentration, the particle size of metal oxide, metal oxyhydroxide, and metal hydroxide can be controlled. In addition, in a washing machine for a dyeing fastness tester according to JIS L 0821, JIS L 080
In the dye fastness test according to 1 to C06, metal oxides, metal oxyhydroxides, and metal hydroxides did not fall off from the fibers. Energy transfer means include heat transfer, convection,
Thermal energy due to radiation or the like, wave energy such as ultraviolet rays, infrared rays, electromagnetic waves, and X-rays are appropriately used.

Next, a method for binding or fixing sulfur or a compound containing sulfur to a synthetic fiber coated with a metal oxide, a metal oxyoxide or a metal hydroxide will be described. Sulfur or a compound containing sulfur is a reducing sulfur compound such as sulfur powder, hydrogen sulfide, sodium thiosulfate, ammonium thiosulfate, metal sulfide such as sodium sulfide, potassium sulfide, iron sulfide, other persulfide, a compound containing sulfur, etc. There is no particular limitation.

Sulfur or a compound containing sulfur is a metal oxide, a metal oxyoxide, a metal hydroxide and a partial redox compound coated on a synthetic fiber due to the electronic properties of elemental sulfur.
Easily chemically bonded by substitution reaction or the like. In addition, the fine particles produced as a result are fixed. Further, fine particles of sulfur or a compound containing sulfur produced by the reaction of sulfur powder or a compound containing sulfur adhere to the metal oxide, the metal oxyoxide, and the metal hydroxide coated on the synthetic fiber. In this case, sulfur or a compound containing sulfur is dissolved or suspended in water, water containing an acid or alkali, or an organic solvent, and a metal oxide, a metal oxyoxide or a metal hydroxide is added to the suspension. The coated synthetic fiber may be dipped. If necessary, the suspension may be cooled and heated.

Examples of the synthetic fiber used in the present invention include rayon, aliphatic polyamide fiber, polyester fiber, aromatic polyamide fiber, carbon fiber, polypropylene, polyethylene, polyester, acrylic resin, vinylon, polyurethane fiber, and the like. Although the molecular weight distribution is not limited, any spinnable raw material can be used. However, aromatic polyamide fibers, aliphatic polyamide fibers, polyester fibers, carbon fibers, rayon and the like are generally used as the high strength and high elasticity fibers.

The polyamide fiber is a polymer compound having an acid amide bond and a hydrocarbon moiety in the molecule, and the aliphatic polyamide fiber is a homopolymer of polyamide 6, polyamide 66, polyamide 610, polyamide 12 or the like. , Polyamide 6/66, polyamide 6/1
2. Polyamide 6 such as polyamide 6/66/610
Examples thereof include copolymer polyamides with a resin, and the aromatic polyamide fibers include poly (p-phenylenephthalamide) and its derivative fibers, which may be heat treated after spinning.

Polyester fiber is a polymer compound obtained by polycondensing a polyvalent organic acid and a polyvalent alcohol.
Examples thereof include polyethylene terephthalate, polybutylene terephthalate, polymethylene terephthalate, and poly-p-ethyleneoxybenzoate. Examples of regenerated cellulose fibers include viscose rayon fibers. In addition, any spinnable raw material such as carbon fiber, polyolefin fiber or vinylon fiber can be used. Further, these resins may be used alone or in combination of two or more kinds, and fibers prepared by blending two or more kinds of resins in a fiber manufacturing process or core-sheath type or parallel type composite fibers Can also be used.

The fiber may be in any form as long as it is used as a reinforcing fiber such as filament, staple, tape yarn, woven fabric, net or the like. The rubber is not particularly limited, but natural rubber, styrene-butadiene rubber, butadiene rubber,
Isoprene rubber, butyl rubber, ethylene / propylene /
Examples include highly saturated or fully saturated rubbers such as diene rubber, highly saturated nitrile rubber, ethylene / propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, epichlorohydrin rubber, fluororubber, etc., alone or in a mixture.

The adhesion between the rubber compound and the synthetic fiber is improved by coating the surface of the synthetic fiber with a metal hydroxide, a metal oxyhydroxide or a metal hydroxide, and then adding sulfur or a compound containing sulfur. It is believed that, by binding or sticking, it interacts with sulfur or a compound containing sulfur contained in the rubber compound.

[0017]

【Example】

Example 1 As the fiber, aromatic, polyamide fiber (Kepler 950 (1500 d, which is a polymer of paraphenylenediamine) is used.
/ 2)) was used. A 10 g / l-FeCl ₃ aqueous solution was prepared, heated to 70 ° C., and then the above fibers were immersed in a reaction solution adjusted to pH 1.8 with NaOH, and held for 10 minutes.
Next, the fibers are taken out from the liquid, thoroughly washed with water,
Dry at 24 ° C. for 24 hours. As an iron compound on the surface of the fiber,
Adhesion of β-FeOOH was confirmed by X-ray diffraction. It was confirmed that 0.002% by weight was attached to the fiber by ashing the fiber and weighing the residue. 1
The above fiber was immersed in a reaction solution prepared by dissolving sulfur powder in diethylamine at a concentration of g / l and refluxed for 60 minutes. The fiber was taken out, washed thoroughly with water, and dried at 80 ° C. for 24 hours. It was confirmed by X-ray diffraction that sulfur was bound to β-FeOOH.

Next, the following composition was kneaded at 60 ° C. to prepare two 3 mm-thick rubber sheets. 1cm between the rubber sheets
The above fiber was sandwiched between and pressed at 145 ° C. for 30 minutes to carry out crosslinking. Rubber compounding NR RSS # 1: 100 parts ZnO # 1: 5 parts Show Black N326: 50 parts Stearic acid: 4 parts Nocceller M: 1 part Sulfanics A: 3 parts This rubber sheet is cut into 10 mm length and 15 mm width, J
According to IS L1017, rubber and fiber are 100 mm /
The pull-out strength was measured at a pulling speed of minutes. The result is 5.
It was 6 kg / cm.

Example 2 As in Example 1, the aromatic polyamide fiber having β-FeOOH attached thereto was immersed in an aqueous solution in which Na ₂ S was dissolved at a concentration of 1 g / l for 10 minutes. The fibers were taken out, washed thoroughly with water, and dried for 24 hours. As a result, a fiber in which sulfur was bound to β-FeOOH was obtained. Example 1
Two rubber sheets were prepared in the same manner as above, fibers were sandwiched between the sheets, and treated in the same manner. The pull-out strength from the rubber was measured as in Example 1, and the result was 5.7 kg / cm.

Example 3 A 10 g / l-CuCl ₂ aqueous solution was prepared, and the same aromatic polyamide fiber as in Example 1 was immersed in a reaction solution adjusted to pH 3.8 with NaOH and heated to 70 ° C. for 10 minutes. Held Next, from the liquid, take out the aromatic polyamide fiber,
It was thoroughly washed with water and dried at 80 ° C. for 2 hours. CuCl ₂ · 3Cu (OH) ₂ adheres as a copper compound, and further CuC
l ₂ · 3Cu (OH) is of ₂ to sulfur is attached, X
Confirmed by line diffraction. It was confirmed that 0.004 (% by weight) was attached to the fibers by ashing the fibers and weighing the residue. The above fiber was immersed in an aqueous solution in which Na ₂ S was dissolved at a concentration of 1 g / l for 10 minutes. The fibers were taken out, washed thoroughly with water, and dried for 24 hours. Example 1
Two rubber sheets were prepared in exactly the same manner as above, and fibers were sandwiched between the sheets, and treated in the same manner. The pull-out strength from the rubber was measured as in Example 1, and the result was 5.3 kg / cm.

Example 4 Instead of aromatic and polyamide fibers, polyethylene terephthalate resin was wet-spun to obtain 2d / 375 2 fibers.
30 T / 10 cm (S) upper twist and 30 T / lower twist
3000d / 2000 consisting of 10 cm (Z) twist structure
Except for using this polyester cord, the same treatment as in Example 3 was performed to sandwich the fiber between the two rubber sheets, and the treatment was performed in exactly the same manner as in Example to measure the pulling strength of the fiber from the rubber. The result was 5.9 kg / cm.

Comparative Example 1 The aromatic polyamide used in Example 1 (Kepler 950 (a polymer of paraphenylenediamine) (1500 d /
2)) was sandwiched between untreated rubber sheets in exactly the same manner as in Example 1, and pressed at 145 ° C. for 30 minutes. The pull-out strength of this rubber sheet was measured in the same manner as in Example 1. The result was 4.3 kg / cm.

Comparative Example 2 The untreated polyester cord used in Example 4 was treated in the same manner as in Example 4 except that the pull-out strength from the rubber was measured. The result was 4.1 kg / cm.

COMPARATIVE EXAMPLE 3 The same treatment as in Comparative Example 1 was carried out except that the fibers treated with the same treatment as in Example 1 and having β-FeOOH attached thereto (without sulfur bonding treatment) were used. Then, the pull-out strength of the rubber was measured. The result is 4.8 kg
/ Cm.

Comparative Example 4 CuCl ₂ .3Cu (OH) ₂ shown in Example 3
The pull-out strength of the rubber was measured in the same manner as in Comparative Example 2 except that the polyester cord used in Comparative Example 2 which was subjected only to the adhesion treatment and not subjected to the sulfur bonding treatment was used. The result was 5.0 kg / cm.

[0026]

The rubber composition reinforced by the synthetic fiber comprising the synthetic fiber and the rubber compound has a coating of a metal oxide, a metal oxyhydroxide or a metal hydroxide as the synthetic fiber, and further has a sulfur content. Alternatively, by using a compound in which a sulfur-containing compound is bonded or fixed, a rubber composition in which the adhesiveness between the synthetic fiber and the rubber compound is remarkably improved can be obtained.

Claims (3)

[Claims] 1. A surface having at least one coating layer selected from metal oxides, metal oxyoxides, and metal hydroxides,
Further, a synthetic fiber-reinforced rubber composition comprising a synthetic compound fiber having sulfur or a compound containing sulfur bonded or fixed thereto, and a rubber compound. 2. The synthetic fiber reinforcement according to claim 1, wherein the synthetic fiber is at least one of aromatic polyamide fiber, aliphatic polyamide fiber, polyester fiber, rayon, carbon fiber, polypropylene, polyethylene, acrylic, vinylon and polyurethane fiber. Rubber composition. 3. Metals such as metal oxides, metal oxyhydroxides and metal hydroxides are Fe, Cr, Mn, Cu, Co and N.
The synthetic fiber-reinforced rubber composition according to claim 1, which is at least one selected from the group consisting of i, V, Al, Si, and Ga.