CN104956000B - For enhancing the carbon fiber line of rubber product and using the rubber product of the carbon fiber line - Google Patents

Abstract

The present invention provides bending fatigue resistance and the high carbon fiber line of cementability.Disclosed carbon fiber line is the carbon fiber line for enhancing rubber product.The carbon fiber line includes: carbon fiber, the 1st overlay film being formed on carbon fiber and the 2nd overlay film formed in a manner of covering the 1st overlay film.1st overlay film contains phenolic resin and without containing rubber constituent.2nd overlay film contains rubber constituent.Moreover, the 1st overlay film ratio shared in the gross mass of carbon fiber and the 1st overlay film is in the range of 0.5 mass of mass %~10 %.

Description

Carbon fiber yarn for reinforcing rubber products and rubber product using the same

technical field

The present invention relates to carbon fiber threads for reinforcing rubber products and rubber products using the carbon fiber threads.

Background technique

Rubber belts and chains are used for driving camshafts of internal combustion engines for automobiles, driving auxiliary machines such as injection pumps, and power transmission of industrial machinery. Generally speaking, a rubber band consists of rubber and reinforcing wires embedded in the rubber. The strength of the rubber belt depends on the strength of the reinforcing wire, so the reinforcing wire is an important component that determines the life of the rubber belt. Such reinforcing wires have been proposed in the past (for example, Patent Document 1).

Glass fibers are mainly used as reinforcing fibers used in reinforcing threads for rubber products. However, with the development of science and technology in recent years, there are increasing cases where glass fibers cannot sufficiently satisfy the required properties. Therefore, fibers such as aramid fibers, polyparaphenylene benzobisoxazole fibers, and carbon fibers are being studied as reinforcing fibers that replace glass fibers. Among these fibers, carbon fibers have the advantages of high strength and elastic modulus, and are therefore particularly preferred as reinforcing fibers.

prior art literature

Patent Literature

Patent Document 1: International Publication No. 2006/001385

SUMMARY OF THE INVENTION

The problem to be solved by the invention

However, in recent years, the performance required for reinforcing wires has increased, and thus further resistance to bending fatigue is required. In addition, when carbon fibers are used as reinforcing fibers, there is a problem that the adhesion between the carbon fibers and the base rubber is insufficient. Here, one of the objects of the present invention is to provide a carbon fiber wire having high bending fatigue resistance and adhesiveness.

solution to the problem

In order to achieve the above objects, the present invention provides carbon fiber threads for reinforcing rubber products. The carbon fiber yarn includes carbon fibers, a first coating formed on the carbon fibers, and a second coating formed so as to cover the first coating, the first coating containing a phenolic resin and not containing a rubber component, and the above The second coating film contains a rubber component, and the ratio of the first coating film to the total mass of the carbon fibers and the first coating film is in the range of 0.5 mass % to 10 mass %.

Invention effect

According to the present invention, a carbon fiber wire having high bending fatigue resistance and high adhesiveness can be obtained.

Description of drawings

FIG. 1 is a diagram schematically showing a bending test performed in the example.

Detailed ways

Embodiments of the present invention will be described below. In addition, in the following description, although embodiment of this invention is described by way of example, this invention is not limited to the example described below. In the following description, specific numerical values and materials may be exemplified, but other numerical values and materials may be applied as long as the effects of the present invention can be obtained. In addition, the compounds described below may be used alone or in combination of two or more unless otherwise specified.

(carbon fiber wire)

The carbon fiber yarn of the present invention for use in reinforcing rubber products will be described below. The carbon fiber yarn of the present invention includes carbon fibers, a first coating film formed on the carbon fibers, and a second coating film formed to cover the first coating film. The first coating film contains a phenolic resin and does not contain a rubber component. The second coating film contains a rubber component. The ratio of the first coating to the total mass of the carbon fibers and the first coating is in the range of 0.5% by mass to 10% by mass.

In the carbon fiber yarn of the present invention, the carbon fiber is protected by the resin component of the first coating. Therefore, damage to the carbon fiber due to friction is reduced, and the bending fatigue resistance of the carbon fiber wire is improved. In addition, by using the resin component, the adhesion between the carbon fibers and the first coating film is improved, and as a result, the adhesion strength of the carbon fiber strands is improved.

The carbon fibers are not particularly limited, and known carbon fibers used as reinforcing fibers can be used. Further, the reinforcing fibers contained in the carbon fiber yarn of the present invention are basically only carbon fibers, but a small amount of fibers other than carbon fibers may be contained as long as the effects of the present invention can be obtained. The ratio of the carbon fiber to the reinforcing fiber contained in the carbon fiber yarn of the present invention is usually 99% by mass or more, and typically 100% by mass. The carbon fibers may be carbon fibers bundled with carbon fiber filaments.

The carbon fiber yarn of the present invention may contain only one carbon fiber, or may contain a plurality of carbon fibers. When the carbon fiber yarn of the present invention contains a plurality of carbon fibers, the lower twist may be used. Alternatively, they may be twisted together to form a top twist. The number of twists is not particularly limited, and may be in the range of 2 to 10 or more. The number of twists of the lower twist and the upper twist is not particularly limited, but is usually in the range of 0.1 to 8.0 times/25 mm, preferably 0.6 to 4.0 times/25 mm. The method of twisting is not limited, and twisting can be carried out by a general method using a flyer twister, a ring twister, or the like. The directions of the lower twist and the upper twist may be the same or different. The bending fatigue resistance can be improved by making the direction of the lower twist and the upper twist the same direction.

The number of filaments constituting the carbon fiber is, for example, in the range of 500 to 48,000. The type of carbon fiber filaments is not particularly limited. The diameter of the carbon fiber filaments is not particularly limited. The diameter of the carbon fiber filaments is preferably in the range of 4 μm to 12 μm, more preferably in the range of 5 μm to 8 μm, and still more preferably in the range of 5 μm to 7 μm.

(1st coating)

The first coating is a coating formed directly on the carbon fibers. As described above, the first coating is a coating containing a phenolic resin and not containing a rubber component. Here, the phenol resin refers to a copolymer of phenols (including phenol) and formaldehyde. Phenols refer to aromatic hydrocarbons (benzene, naphthalene) substituted with at least a hydroxyl group (—OH). Examples of phenols include phenols (monophenols), dihydric phenols, halogenated phenols, alkylphenols, nitrophenols, phenolsulfonic acids, and naphthols. Examples of dihydric phenols include resorcinol, catechol, hydroquinone. Examples of halogenated phenols include chlorophenol, bromophenol. Examples of alkylphenols include cresol, butylphenol.

The phenolic resin may be a copolymer of two or more phenols and formaldehyde. For example, the phenol resin may be a phenol other than resorcinol, and a copolymer of resorcinol and formaldehyde. The phenols in this case may be p-chlorophenol or phenol. Specifically, for example, Nagase Chemical Co., Ltd.'s Danabod, and Yoshimura Oil Chemical Co., Ltd.'s ュカレヅソ (for example, a model number: KE910 or KE912) can be mentioned.

In the carbon fiber yarn of the present invention, the ratio of the first coating to the total mass of (carbon fiber + first coating) is in the range of 0.5 mass % to 10 mass %, preferably in the range of 1.0 mass % to 6.0 mass % , more preferably in the range of 2.0 mass % to 4.0 mass %.

(Other coatings)

The second coating usually contains a rubber component. Examples of the rubber component contained in the second coating film include butadiene-styrene copolymer, dicarboxylated butadiene-styrene copolymer, butadiene rubber, dichloroprene, vinylpyridine-butadiene Ethylene-styrene terpolymer, chloroprene, chlorosulfonated polyethylene, acrylonitrile-butadiene copolymer, hydrogenated nitrile butadiene rubber (H-NBR). In addition, the hydrogenated nitrile rubber may be a carboxyl group-modified hydrogenated nitrile rubber.

The second coating can be formed by using a second treatment agent to be described later. The ratio of the second coating to the total mass of (carbon fiber + first coating + second coating) is, for example, in the range of 5 to 30 mass %, preferably in the range of 10 to 25 mass %, More preferably, it exists in the range of 13 mass % - 19 mass %.

The carbon fiber yarn of the present invention may further include a third coating film formed to cover the second coating film. By forming the third coating, the adhesiveness with the base rubber can be further improved. The ratio of the third coating to the total mass of (carbon fiber + first coating + second coating + third coating) is in the range of, for example, 0.5 to 8.0 mass %, preferably 1.0 to 5.0 mass % The range of mass % is more preferably in the range of 1.8 mass % to 3.8 mass %.

(An example of a method for producing a carbon fiber yarn)

An example of a method for producing the carbon fiber yarn of the present invention will be described below. First, prepare the carbon fiber. Then, the first coating film is formed so as to cover the carbon fibers. The first coating can be formed by using the first treatment agent for forming the first coating. Specifically, the first coating film can be formed by applying the first treatment agent on the carbon fibers and then drying them.

The first treatment agent contains the components of the first coating. Specifically, the first treatment agent contains the above-mentioned phenol resin and does not contain a rubber component (latex, etc.). An example of the first treatment agent is an aqueous treatment agent obtained by dispersing the above-mentioned phenol resin in water.

After the formation of the first coating, the second coating is formed so as to cover the first coating. The second coating can be formed by using the second treatment agent for forming the second coating. Specifically, the second coating can be formed by applying the second treatment agent so as to cover the first coating, followed by drying.

Examples of the second treatment agent include an aqueous treatment agent in which the above-mentioned rubber component is dispersed in an aqueous solvent. An example of the second treatment agent is the second aqueous treatment agent used in Example 1 to be described later (see Table 1). In addition, the treatment agent disclosed in International Publication No. WO 2006/001385 as a treatment agent for forming a film can also be used as the second treatment agent.

The second treatment agent usually contains a rubber component and a crosslinking agent. As the crosslinking agent, a known crosslinking agent can be used. A typical example of the second treatment agent is an aqueous treatment agent that is not a so-called RFL liquid. The RFL liquid is a treatment liquid mainly composed of a mixture of an initial condensate of resorcinol and formaldehyde and a rubber latex. A typical example of the second treatment agent is an aqueous treatment agent that does not contain an initial condensate of resorcinol and formaldehyde, but contains a rubber latex and a crosslinking agent. In this example, 5-100 mass parts of crosslinking agents may be contained with respect to 100 mass parts of rubber latexes, for example. In another typical example of the second treatment agent, in addition to the rubber latex and the crosslinking agent, a filler such as carbon black and silica, a resin, a plasticizer, an antiaging agent, a stabilizer, a metal oxide, etc. may be contained. .

As the crosslinking agent, for example, a quinonedioxime-based crosslinking agent such as p-quinonedioxime can be used. In addition, methacrylate-based crosslinking agents such as lauryl methacrylate and methyl methacrylate can be used. In addition, alkenes such as DAF (diallyl fumarate), DAP (diallyl phthalate), TAC (triallyl cyanurate) and TAIC (triallyl isocyanurate) can be used Propyl crosslinking agent. In addition, maleimide-based crosslinking agents (maleimide or maleimide derivatives). In addition, a diisocyanate compound (organic diisocyanate) can be used, a polyisocyanate can also be used, and an aromatic nitroso compound can also be used. Additionally sulfur, other crosslinking agents can be used. Among them, at least one selected from the group consisting of diisocyanate compounds, polyisocyanates, aromatic nitroso compounds, and maleimide-based crosslinking agents is preferably used, for example, maleimide-based crosslinking agents are preferably used. By using these crosslinking agents, the adhesiveness between the reinforcing fiber and the base rubber can be specifically improved.

The method of applying the first treatment agent and the second treatment agent is not limited, and a known method can be applied. For example, carbon fibers and threads can be dipped in the treatment agent. In addition, the method and conditions of drying the applied treatment agent are not particularly limited, and a known method can be applied. For example, moisture can be removed by drying in an atmosphere of 80 to 300° C. for 0.1 to 3 minutes. Moreover, the formation method of a 3rd coating film is not specifically limited either, A well-known method can be applied.

(rubber products)

The rubber product of the present invention contains the carbon fiber strand of the present invention. That is, the rubber product of the present invention is reinforced by the carbon fiber strands of the present invention. The rubber product is not particularly limited. Examples of the rubber product of the present invention include tires for automobiles and bicycles, and transmission belts. Examples of drive belts include meshing drive belts, friction drive belts, and the like. Examples of meshing transmission belts include toothed belts represented by timing belts for automobiles and the like. Examples of friction drive belts include: flat belts, round belts, V-belts, V-ribbed belts, and the like.

The rubber product of the present invention is formed by embedding the carbon fiber strands of the present invention in a rubber composition (base rubber). The method of burying the carbon fiber strands in the base rubber is not particularly limited, and a known method can be applied. The carbon fiber thread of the present invention is embedded in the rubber product (eg, rubber tape) of the present invention. Therefore, the rubber article of the present invention has high resistance to bending fatigue. Therefore, the rubber product of the present invention is particularly suitable for applications such as timing belts for vehicle engines.

The rubber of the rubber composition for embedding the carbon fiber strands of the present invention is not particularly limited, and may be chloroprene rubber, chlorosulfonated polyethylene rubber, ethylene propylene rubber, hydrogenated nitrile rubber, or the like. From the viewpoint of water resistance and oil resistance, at least one rubber selected from the group consisting of hydrogenated nitrile rubber and hydrogenated nitrile rubber in which a zinc acrylate derivative is dispersed is preferable. The base rubber may also comprise carboxyl-modified hydrogenated nitrile rubber. In addition, from the viewpoint of adhesiveness, it is preferable that the coating film on the outermost surface of the carbon fiber yarn and the rubber composition of the rubber product contain the same kind of rubber, or are composed of the same kind of rubber.

Example

Hereinafter, the present invention will be described in more detail using examples.

(Example 1)

First, 6000 carbon fiber filaments are bundled to form bundles of filaments. As the carbon fiber filaments, filaments with an average diameter of 7 μm were used. Then, the bundle of carbon fiber filaments is immersed in the first aqueous treatment agent. As the first aqueous treatment agent, a treatment agent obtained by dispersing a p-chlorophenol-resorcinol-formaldehyde copolymer in water was used. Specifically, as the first aqueous treatment agent, a treatment agent obtained by diluting Nagase Chemical Co., Ltd.'s Danabod with water to 8 times was used. Hereinafter, the first aqueous treatment agent used in Example 1 may be referred to as "treatment agent (A)".

Then, the carbon fiber coated with the first aqueous treatment agent was dried at 150° C. for 2 minutes to obtain one carbon fiber yarn having a first coating. The 2nd aqueous treatment agent shown in Table 1 was apply|coated to this carbon fiber thread, and it dried at 200 degreeC for 2 minutes, and formed the 2nd coating film.

【Table 1】

(*1) Zetpol Latex (carboxy-modified and hydrogenated type: manufactured by Zeon Co., Ltd.)

Then, the carbon fiber yarn on which the second coating was formed was twisted in one direction at a rate of 2.0 times/25 mm. Moreover, in Example 1, the 1st coating film was formed so that the ratio of the 1st coating film in (carbon fiber + 1st coating film) might become 0.5 mass %. Moreover, the 2nd coating film was formed so that the ratio of the 2nd coating film in (carbon fiber + 1st coating film + 2nd coating film) might become 16 mass %.

Then, the third coating film was formed by applying the third treatment agent having the composition shown in Table 2 on the second coating film of the above-mentioned lines, and drying it. The ratio of the third coating to the total mass of (carbon fiber + first coating + second coating + third coating) was 3.0%. In this way, the carbon fiber yarn of Example 1 was produced.

【Table 2】

Element Proportion (parts by mass) Chemlok 233X(*1) 100 Xylene 100

( ^* 1) Made by Lord Far East Inc.

(Examples 2 to 11)

Carbon fiber yarns of Examples 2 to 11 were produced under the same conditions as in Example 1, except that the ratios of the first and second coatings were changed. These ratios are shown in Table 4 to be described later. In addition, the ratio of the third coating film to the entire wire was the same as that of Example 1 (the same applies to the following Examples and Comparative Examples).

(Examples 12 to 17)

Carbon fiber yarns of Examples 12 to 17 were produced under the same conditions as in Example 1, except that the first aqueous treatment agent was changed and the proportions of the first and second coated yarns in the entire yarn were changed. These ratios are shown in Table 5 described later.

In Examples 12 to 17, as the first aqueous treatment agent, a treatment agent obtained by dispersing a phenol-resorcinol-formaldehyde copolymer in water was used. Specifically, as the first aqueous treatment agent, a treatment agent obtained by diluting Yoshimura Oil Chemicals Co., Ltd.'s ュカレヅソ (model: KE912) to 8 times with water was used. Hereinafter, the first aqueous treatment agent used in Examples 12 to 17 may be referred to as "treatment agent (C)".

(Comparative Example 1)

In Comparative Example 1, the first coating film containing the phenol resin was not formed. In addition, the second coating film is formed by applying the RFL liquid and drying it. Here, as the RFL liquid, a treatment liquid obtained by mixing a modified hydrogenated nitrile rubber latex with an initial condensate of resorcinol and formaldehyde is used. The ratio of the second coating to (carbon fiber+second coating) was 20% by mass.

(Comparative Examples 2 to 4)

In Comparative Examples 2 to 4, the first coating film containing the phenol resin was not formed. Moreover, the 2nd coating film was formed by apply|coating and drying the 2nd aqueous treatment agent used in Example 1. However, the ratio of the second coating to (carbon fiber + second coating) was changed. These ratios are shown in Table 6 described later.

(Comparative Examples 5 to 8)

Carbon fiber yarns of Comparative Examples 5 to 8 were produced under the same conditions as in Example 1, except that the ratios of the first and second coatings were changed in Comparative Examples 5 to 8. The treatment agents used for the formation of the coating film and their ratios are shown in Table 6 described later. In addition, the ratio of the 3rd coating film to the whole line was the same as that of Example 1.

The carbon fiber strands produced in the above Examples and Comparative Examples were embedded in a base rubber having the composition shown in Table 3 to form a flat belt having a width of 10 mm, a length of 300 mm, and a thickness of 3 mm.

【table 3】

Element mass ratio Hydrogenated nitrile rubber (*1) 70 Hydrogenated nitrile rubber containing zinc dimethacrylate (*2) 30 Zinc oxide 10 Stearic acid 1 carbon black 30 Trioctyl trimellitate 5 sulfur 0.1 1,3-Bis(tert-butylperoxyisopropyl)benzene 6 Magnesium oxide 1 4,4'-(α,α-dimethylbenzyl)diphenylamine 0.5 2-mercaptobenzimidazole zinc salt 0.5 Triallyl isocyanurate 1

(*1) Zetpol2020 (manufactured by Zeon Co., Ltd.)

(*2) Zetpo12000L (manufactured by Zeon Co., Ltd.)

The resulting flat belt was subjected to bending tests of 50,000 and 100,000 bending times. The bending test was performed using the bending tester 10 shown in FIG. 1 . The tensile strengths before the bending test and after the bending test were measured for the test pieces, respectively. Here, the tensile strength refers to the breaking strength obtained when a tensile test is carried out with a generally used tensile testing machine and a generally used wire clip. Also, the unit is N/band.

The bending tester 10 of FIG. 1 includes one flat pulley 21 (10 mm in diameter), four guide pulleys 23 , and a motor 22 . First, the produced test piece 20 (flat belt) was stretched over five pulleys. Then, a weight was attached to one end 20 a of the test piece 20 , and a load of 9.8 N was applied to the test piece 20 . In this state, the other end 20 b of the test piece 20 is reciprocated by the motor 22 , and the portion of the flat pulley 21 of the test piece 20 is repeatedly bent. Bend tests are performed at room temperature. Thus, after the bending test of the test piece 20 was performed, the tensile strength of the test piece after the bending test was measured.

Then, the ratio of the tensile strength of the test piece after the bending test when the tensile strength of the test piece before the bending test is taken as 100%, that is, the strength retention ratio (%) was obtained. The higher the value of the strength retention ratio, the better the bending fatigue resistance. The strength retention rate after the 50,000-time bending test is referred to as "strength retention rate (1)", and the strength retention rate after 100,000-time bending test is referred to as "strength retention rate (2)", which are shown in Tables 4- 6.

In addition, about the produced carbon fiber yarn, the adhesion test for evaluating the adhesion force with the base rubber was performed. Specifically, first, the canvas, the carbon fiber yarn, and the base rubber sheet were sequentially stacked and pressed under the conditions of 160° C. for 30 minutes, thereby producing a test piece for an adhesion test. The dimensions of the test piece were 25 mm in width, 150 mm in length, and 3 mm in thickness. As the base rubber, a rubber mainly composed of hydrogenated nitrile rubber is used. In the test, first, the carbon fiber wire and the base rubber were clamped by the upper and lower chucks of the tensile testing machine, respectively. Then, the wire and the base rubber were peeled off, and the state of failure was observed. The results are shown in Tables 4-6. "Rubber breakage" in Tables 4 to 6 means that the interface between the carbon fiber strands and the base rubber is not peeled off, but cracks are generated in the base rubber and are broken. "Spots" in Tables 4 to 6 means that most of the wires are peeled off at the interface between the wire and the base rubber, and that there are parts where the rubber is broken. Compared with "spots", the "rubber failure" shows that the bonding strength between the reinforcing wire and the base rubber is higher, that is, the bonding strength between the carbon fiber and the film is higher.

Tables 4 to 6 show the residual rubber ratio. The rubber residual ratio is a value showing the % of the area of the portion where rubber is broken and the rubber remains on the line side of the test piece after the peel test in the area of the entire adhesive surface of the test piece. A rubber residual ratio of less than 80% indicates a poor adhesion state, 80% or more and less than 90% indicates a favorable adhesion state, and 90% or more indicates a more favorable adhesion state.

The production conditions and evaluation results of the carbon fiber yarns of Examples and Comparative Examples are shown in Tables 4 to 6.

【Table 4】

(*1) represents the ratio of the first coating to (carbon fiber + first coating).

(*2) represents the ratio of the second coating to (carbon fiber + first coating + second coating).

【table 5】

The ratios of (*1) and (*2) have the same meanings as (*1) and (*2) in Table 4, respectively.

【Table 6】

The ratios of (*1) and (*2) have the same meanings as (*1) and (*2) in Table 4, respectively.

(*3) The second coating of Comparative Example 1 was formed from the RFL liquid.

As shown in Tables 4 to 6, carbon fiber yarns having high bending fatigue resistance and adhesiveness can be obtained by forming a predetermined first coating film in a predetermined ratio.

Industrial Availability

The present invention can be utilized in carbon fiber yarns for reinforcing rubber and rubber products using the carbon fiber yarns.

Claims (5)

1. A carbon fiber thread for reinforcing rubber products, comprising: carbon fiber, a first coating formed on the carbon fiber, and the second coating formed so as to cover the first coating, The first coating film contains a phenolic resin and does not contain a rubber component, The second coating film contains a rubber component, and the second coating film is formed using a treatment agent that contains the rubber component and does not contain an initial condensate of resorcinol and formaldehyde, The phenolic resin is a phenol other than resorcinol, a copolymer of resorcinol and formaldehyde, Phenols other than the resorcinol are p-chlorophenol or phenol, The rubber component contains hydrogenated nitrile rubber, The ratio of the first coating film to the total mass of the carbon fibers and the first coating film is in the range of 0.5 mass % to 10 mass %. 2 . The carbon fiber yarn according to claim 1 , wherein the treatment agent further contains a crosslinking agent. 3 . 3 . The carbon fiber yarn according to claim 2 , wherein the crosslinking agent is at least one selected from the group consisting of polyisocyanates, aromatic nitroso compounds, and maleimide-based crosslinking agents. 4 . 4. The carbon fiber yarn according to claim 2, wherein the crosslinking agent is at least one selected from the group consisting of diisocyanate compounds, aromatic nitroso compounds, and maleimide-based crosslinking agents. 5. A rubber product comprising the carbon fiber thread of claim 1.