WO2018056055A1

WO2018056055A1 - Rubber composition and transmission belt using same

Info

Publication number: WO2018056055A1
Application number: PCT/JP2017/032093
Authority: WO
Inventors: 大樹土屋; 正吾小林; 圭一郎松尾; 奥野　茂樹
Original assignee: バンドー化学株式会社
Priority date: 2016-09-26
Filing date: 2017-09-06
Publication date: 2018-03-29
Also published as: TWI738877B; TW201815940A

Abstract

In the rubber composition according to the present invention, cellulose nanofibers and carbon black are dispersed in a rubber component having chloroprene rubber or an ethylene-α-olefin elastomer as the main component thereof. The cellulose nanofiber content is 1-20 parts by mass with respect to 100 parts by mass of the rubber component, and the carbon black content is 5-60 parts by mass with respect to 100 parts by mass of the rubber component.

Description

Rubber composition and power transmission belt using the same

The present invention relates to a rubber composition and a transmission belt using the same.

Cellulose nanofibers are attracting attention as chemically stable and physically strong materials. Patent Document 1 discloses that a tire is formed of a rubber composition in which cellulose nanofibers are dispersed and contained in a rubber component such as chloroprene rubber.

JP 2014-088503 A

The present invention is a rubber composition in which cellulose nanofibers and carbon black are dispersed in a rubber component mainly composed of chloroprene rubber or ethylene-α-olefin elastomer, and the content of the cellulose nanofiber is 100 masses of the rubber component. 1 part by mass or more and 20 parts by mass or less with respect to parts, and the content of the carbon black is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component.

The present invention is a transmission belt in which at least a part of the belt body is formed of the rubber composition of the present invention.

It is a perspective view of one piece of a single cogged V belt. It is a perspective view of one piece of a double cogged V belt. It is a figure which shows the pulley layout of the belt running test machine for crack resistance evaluation. It is a figure which shows the pulley layout of the belt running test machine for abrasion resistance evaluation.

Hereinafter, embodiments will be described in detail.

The rubber composition according to the embodiment includes chloroprene rubber (hereinafter referred to as “CR”) or a rubber component mainly composed of ethylene-α-olefin elastomer, cellulose nanofiber (hereinafter referred to as “CNF”), and carbon black. (Hereinafter referred to as “CB”) in which the uncrosslinked rubber composition in which the rubber component is dispersed is heated and pressurized to crosslink the rubber component. The CNF content is 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component, and the CB content is 5 to 60 parts by mass with respect to 100 parts by mass of the rubber component. .

According to the rubber composition according to such an embodiment, CNF and CB are dispersed in the rubber component mainly composed of CR or ethylene-α-olefin elastomer, and the content of CNF is 100 parts by mass of the rubber component. 1 to 20 parts by mass and the content of CB is 5 to 60 parts by mass with respect to 100 parts by mass of the rubber component. The dependency is small, so that the difference in deformation due to the temperature change is small, the loss tangent is small, so that heat generation can be suppressed, and excellent wear resistance can be obtained.

Here, the rubber component is mainly CR or ethylene-α-olefin elastomer. The content of CR or ethylene-α-olefin elastomer in the rubber component is more than 50% by mass, reducing the difference in deformation due to temperature change in dynamic use, suppressing heat generation, and excellent wear resistance From the viewpoint of obtaining the above, it is preferably 80% by mass or more, more preferably 90% by mass or more, and most preferably 100% by mass. In the case where the main component is CR, the rubber component may contain ethylene-α-olefin elastomer, hydrogenated nitrile rubber (H-NBR), styrene butadiene rubber (SBR), and the like. Further, when the main component is an ethylene-α-olefin elastomer, the rubber component may contain CR, hydrogenated nitrile rubber (H—NBR), styrene butadiene rubber (SBR), or the like.

Examples of CR include G-type sulfur-modified CR, W-type mercaptan-modified CR, A-type high crystal CR, low-viscosity CR, carboxylated CR, and the like. When the main rubber component is CR, the CR of the rubber component preferably contains one or more of these, and the difference in deformation due to temperature change in dynamic use is reduced and heat is generated. It is more preferable to contain sulfur-modified CR, more preferably sulfur-modified CR as a main component, and still more preferably only sulfur-modified CR. From the same viewpoint, the rubber component is more preferably composed only of sulfur-modified CR.

Examples of the ethylene-α-olefin elastomer include ethylene / propylene copolymer (EPR), ethylene / propylene / diene terpolymer (hereinafter referred to as “EPDM”), ethylene / octene copolymer, and ethylene / butene copolymer. When the main component of the rubber component is an ethylene-α-olefin elastomer, the ethylene-α-olefin elastomer of the rubber component preferably contains one or more of these, more preferably contains EPDM, and EPDM Is more preferable as a main component.

When the main rubber component is an ethylene-α-olefin elastomer, the ethylene content is preferably 45 to 60% by mass, more preferably 50 to 55% by mass. When the main rubber component is EPDM, examples of the diene component include ethylidene nobornene (ENB), dicyclopentadiene, 1,4-hexadiene, and the like. The diene component is preferably ethylidene nobornene. When the rubber component is EPDM and the diene component is ethylidene nobornene, the ENB content is preferably 5.0% by mass to 10% by mass, more preferably 7.0% by mass to 9.0%. It is below mass%.

CNF is composed of a skeletal component of the plant cell wall obtained by finely loosening plant fibers. Examples of the CNF raw material pulp include pulps of wood, bamboo, rice (rice straw), potato, sugar cane (bagasse), aquatic plants, seaweed, and the like. Of these, wood pulp is preferred.

Examples of CNF include TEMPO oxidized CNF and mechanical defibrated CNF. CNF preferably includes one or two of these, preferably includes TEMPO-oxidized CNF, preferably includes TEMPO-oxidized CNF as a main component, and more preferably includes only TEMPO-oxidized CNF. .

TEMPO-oxidized CNF selectively oxidizes the hydroxyl group at the C6-position in the cellulose molecule to a carboxyl group by acting a co-oxidant on cellulose contained in the raw material pulp using an N-oxyl compound as a catalyst. It is CNF obtained by making it fine. Examples of the N-oxyl compound include 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) free radical and 4-acetamido-TEMPO. Examples of the co-oxidant include hypohalous acid and its salt, halous acid and its salt, perhalogenic acid and its salt, hydrogen peroxide, perorganic acid and the like. Mechanical defibrating CNF is CNF obtained by pulverizing raw material pulp using a kneading machine such as a twin-screw kneader, a high-pressure homogenizer, a grinder, a bead mill, or the like.

The fiber diameter of TEMPO oxidized CNF is, for example, 1 nm or more and 10 nm, and its distribution is narrow. On the other hand, the fiber diameter of mechanical defibrating CNF is several tens to several hundreds nm, and its distribution is wide. Therefore, TEMPO-oxidized CNF and mechanically crushed CNF can be clearly distinguished by the size of the fiber diameter and its distribution.

CNF may contain hydrophobized CNF that has been hydrophobized. Examples of hydrophobized CNF include CNF in which some or all of the hydroxyl groups of cellulose are substituted with hydrophobic groups, and CNF that has been hydrophobized and surface-treated with a surface treatment agent. Examples of the hydrophobization for obtaining CNF in which part or all of the hydroxyl groups of cellulose are substituted with a hydrophobic group include amination, esterification, alkylation, tosylation, epoxidation, arylation and the like. Of these, amination is preferred. Specifically, the aminated hydrophobized CNF is CNF in which the carboxyl group of TEMPO-oxidized CNF is aminated. Examples of the surface treatment agent for obtaining CNF hydrophobized with the surface treatment agent include a silane coupling agent.

The content (A) of CNF in the rubber composition according to the embodiment is 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the rubber component, and the difference in the magnitude of deformation accompanying a temperature change in dynamic use. From the viewpoint of suppressing heat generation and obtaining excellent wear resistance, it is preferably 3 parts by mass or more and 15 parts by mass or less, more preferably 5 parts by mass or more and 10 parts by mass or less.

Examples of CB include channel black; furnace black such as SAF, ISAF, N-339, HAF, N-351, MAF, FEF, SRF, GPF, ECF, and N-234; thermal black such as FT and MT; acetylene Black etc. are mentioned. CB preferably includes one or more of these, more preferably includes FEF, further preferably includes FEF as a main component, and more preferably includes only FEF.

The content (B) of CB in the rubber composition according to the embodiment is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the rubber component, and the difference in deformation due to temperature change in dynamic use is determined. From the viewpoint of reducing heat generation and obtaining excellent wear resistance, it is preferably 10 parts by mass or more and 40 parts by mass or less, more preferably 10 parts by mass or more and 30 parts by mass or less. The sum (A + B) of the CNF content (A) and the CB content (B) in the rubber composition according to the embodiment is preferably 15 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the rubber component. More preferably, it is 60 mass parts or less, More preferably, it is 40 mass parts or less.

The ratio (A / B) of the CNF content (A) to the CB content (B) in the rubber composition according to the embodiment is preferably 0.050 or more and 2.0 or less, more preferably 1.0 or less. More preferably, it is 0.5 or less. The content (A) of CNF with respect to 100 parts by mass of the rubber component in the rubber composition according to the embodiment reduces the difference in the magnitude of deformation accompanying temperature change in dynamic use and suppresses heat generation and has excellent wear resistance. From the viewpoint of obtaining properties, the content is preferably less than the CB content (B).

The rubber composition according to the embodiment may contain dispersed short fibers. Examples of short fibers include para-aramid short fibers, meta-aramid short fibers, nylon 6 short fibers, nylon 6,6 short fibers, nylon 4,6 short fibers, polyethylene terephthalate short fibers, polyethylene naphthalate short fibers, and the like. Can be mentioned. The short fibers preferably include one or more of these, more preferably include para-aramid short fibers, preferably include para-aramid short fibers as a main component, and para-aramid short fibers. It is still more preferable that it is comprised only by.

Para-aramid short fibers include polyparaphenylene terephthalamide short fibers (for example, DuPont Kevlar, Teijin Twaron) and copolyparaphenylene-3,4'-oxydiphenylene terephthalamide short fibers ( For example, Teijin's Technora). The para-aramid short fibers preferably contain one or two of these, more preferably contain copolyparaphenylene-3,4'-oxydiphenylene terephthalamide short fibers, and copolyparaphenylene- It is more preferable to mainly include short fibers of 3,4'-oxydiphenylene terephthalamide, and it is even more preferable that the short fibers of copolyparaphenylene-3,4'-oxydiphenylene terephthalamide are used alone.

The fiber length of the short fibers is preferably 0.5 to 5.0 mm, more preferably 1.0 to 3.0 mm. The fiber diameter of the short fiber is preferably 5.0 μm or more and 70 μm or less, more preferably 10 μm or more and 50 μm or less.

The content (C) of the short fiber in the rubber composition according to the embodiment is from the viewpoint of reducing the difference in the magnitude of deformation accompanying temperature change in dynamic use and suppressing heat generation and obtaining excellent wear resistance. The amount is preferably 3 parts by mass or more and 25 parts by mass or less, more preferably 5 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the rubber component. The sum (A + C) of the CNF content (A) and the short fiber content (C) in the rubber composition according to the embodiment reduces the difference in deformation due to temperature change in dynamic use. From the viewpoint of suppressing heat generation and obtaining excellent wear resistance, the amount is preferably 15 parts by weight or more and 40 parts by weight or less, more preferably 25 parts by weight or less with respect to 100 parts by weight of the rubber component. The sum (A + B + C) of the CNF content (A), the CB content (B), and the short fiber content (C) in the rubber composition according to the embodiment is the deformation due to temperature change in dynamic use. From the viewpoint of reducing the difference in size and suppressing heat generation and obtaining excellent wear resistance, it is preferably 30 parts by mass or more and 90 parts by mass or less, more preferably 60 parts by mass or less, with respect to 100 parts by mass of the rubber component. More preferably, it is 40 parts by mass or less.

The ratio (A / C) of the CNF content (A) to the short fiber content (C) in the rubber composition according to the embodiment reduces the difference in deformation due to temperature change in dynamic use. In addition, from the viewpoint of suppressing heat generation and obtaining excellent wear resistance, it is preferably 0.050 or more and 1.3 or less, and more preferably 0.40 or less. The content (A) of CNF with respect to 100 parts by mass of the rubber component in the rubber composition according to the embodiment reduces the difference in the magnitude of deformation accompanying temperature change in dynamic use and suppresses heat generation and has excellent wear resistance. From the viewpoint of obtaining properties, the content is preferably less than the short fiber content (C).

In the uncrosslinked rubber composition forming the rubber composition according to the embodiment, a crosslinking agent of CR or ethylene-α-olefin elastomer is blended. Examples of CR crosslinking agents include metal oxides such as zinc oxide and magnesium oxide. The cross-linking agent is preferably used in combination with zinc oxide and magnesium oxide. The compounding amount of zinc oxide is preferably 3 parts by mass or more and 7 parts by mass or less, more preferably 4 parts by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the rubber component. The compounding amount of magnesium oxide is preferably 3 parts by mass or more and 7 parts by mass or less, and more preferably 4 parts by mass or more and 6 parts by mass or less with respect to 100 parts by mass of the rubber component. Examples of the crosslinking agent for the ethylene-α-olefin elastomer include organic peroxides and sulfur. As the crosslinking agent, an organic peroxide may be used, sulfur may be used, and furthermore, they may be used in combination. The compounding quantity of an organic peroxide or sulfur is 1 mass part or more and 5 mass parts or less with respect to 100 mass parts of rubber components.

The rubber composition according to the embodiment may further contain rubber compounding agents such as a plasticizer, a processing aid, a vulcanization acceleration aid, and a vulcanization accelerator.

The rubber hardness measured using a type A durometer based on JISK6253: 2012 in the rubber composition according to the embodiment is preferably A80 or more and A95 or less.

In the rubber composition according to the embodiment, the tensile strength measured in line with JISK6251: 2010 is preferably 20.0 MPa or more and 35.0 MPa or less, more preferably 25.0 MPa or more and 30.0 MPa or less. . In the rubber composition according to the embodiment, the elongation at break measured in accordance with JISK6251: 2010 is preferably 10% or more and 40% or less, more preferably 15% or more and 30% or less.

Based on JISK6394: 2007 in the rubber composition according to the embodiment, the storage elastic modulus (E ′) in the reverse direction at 25 ° C. measured as a dynamic strain of 1.0% and a frequency of 10 Hz is preferably It is 10.0 MPa or more and 70.0 MPa or less, More preferably, it is 15.0 MPa or more and 40.0 MPa or less. The storage elastic modulus in the reverse direction at 100 ° C. is preferably 10.0 MPa or more and 55.0 MPa or less, more preferably 13.0 MPa or more and 25.0 MPa or less. The ratio of the warp elastic modulus in the anti-row direction at 100 ° C. to the warp elastic modulus at 25 ° C. is preferably 0.70 or more, more preferably 0.80 or more, and still more preferably Is 0.90 or more.

Based on JISK6394: 2007 in the rubber composition according to the embodiment, the loss tangent (tan δ) in the reverse direction at 25 ° C. measured as a dynamic strain of 1.0% and a frequency of 10 Hz is preferably 0.17 or less. More preferably, it is 0.10 or less. The loss tangent in the reverse direction at 100 ° C. is preferably 0.13 or less, more preferably 0.080 or less.

In the rubber composition according to the embodiment having the above-described configuration, when CR is mainly used as a rubber component, a master batch in which CNF is dispersed in CR is prepared by mixing CNF into CR latex and removing the solvent. An uncrosslinked rubber composition is obtained by mixing and kneading a rubber compounding agent containing CB with a master batch or a rubber component such as CR kneaded and diluted in the master batch. It can be obtained by crosslinking the rubber component by heating and pressurizing the rubber composition. When ethylene-α-olefin elastomer is mainly used as a rubber component, a dispersion in which hydrophobic CNF is dispersed in a solvent such as toluene and an ethylene-α-olefin elastomer are dissolved in a solvent such as toluene. A masterbatch in which CNF is dispersed in an ethylene-α-olefin elastomer is prepared by mixing with the solution and removing the solvent, and the masterbatch may be used.

The rubber composition according to the embodiment forms at least a part of a belt body of a transmission belt, in particular, a transmission belt, because the difference in the magnitude of deformation due to temperature change in dynamic use can be reduced and heat generation can be suppressed. It can use suitably as a material to do.

FIG. 1A shows a single cogged V-belt B1 as an example of a transmission belt. The single cogged V-belt B1 is used as a transmission belt for a small scooter or an agricultural machine, for example.

The single cogged V-belt B1 has a trapezoidal cross-sectional shape in which a compression rubber layer 11 on the belt inner peripheral side, an extended rubber layer 12 on the belt outer peripheral side, and an adhesive rubber layer 13 therebetween are laminated and integrated. It has a rubber belt body 10. A core wire 14 is embedded in an intermediate portion in the thickness direction of the adhesive rubber layer 13 so as to form a spiral having a pitch in the belt width direction. An inner reinforcing cloth 15 is affixed to the surface of the compressed rubber layer 11 constituting the inner peripheral surface of the belt, and an outer reinforcing cloth 16 is affixed to the surface of the stretched rubber layer 12 constituting the outer peripheral surface of the belt. ing. An inner cog 17 is disposed at a constant pitch in the belt length direction on the belt inner peripheral side, while a flat belt back surface is formed on the belt outer peripheral side.

FIG. 1B shows a double cogged V-belt B2 as another example of a transmission belt. This double cogged V-belt B2 is used, for example, as a transmission belt for a large buggy or a large scooter.

Similar to the single cogged V-belt B1, the double cogged V-belt B2 includes a belt body 10 composed of a compression rubber layer 11, an extended rubber layer 12, and an adhesive rubber layer 13, a core wire 14 embedded in the adhesive rubber layer 13, and a belt. It has the inner side reinforcement cloth 15 stuck on the inner peripheral surface and the outer side reinforcement cloth 16 stuck on the outer peripheral surface of the belt. An inner cog 17 and an outer cog 18 are disposed at a constant pitch in the belt length direction on the belt inner peripheral side and the belt outer peripheral side, respectively.

In these single cogged V-belt B1 and double cogged belt B2, it is preferable that at least a part of the belt main body 10, particularly the compressed rubber layer 11, is formed of the rubber composition according to the embodiment.

In the single cogged V-belt B1 and double cogged belt B2 used for speed change applications, the winding diameter on the pulley is fluctuated and violently bent. At this time, heat is generated by bending, but if the deformation of the belt increases as the temperature rises, it is difficult to maintain a stable speed change operation, and if the heat generation itself is large, it causes energy loss. This leads to a decrease in power transmission efficiency. However, in the single cogged V belt B1 and the double cogged belt B2 using the rubber composition according to the embodiment, since the difference in deformation due to a temperature change is small in dynamic use such as bending, a stable speed change operation is achieved. Since it can maintain and heat generation is suppressed, the fall of power transmission efficiency can be suppressed small. In addition, high wear resistance is required for the friction transmission belts such as the single cogged V belt B1 and the double cogged belt B2, but if the rubber composition according to the embodiment is used, excellent wear resistance can be obtained.

In the above embodiment, the single cogged V belt B1 and the double cogged belt B2 are shown as the transmission belt in which at least a part of the belt main body is formed of the rubber composition according to the embodiment. However, the belt is not particularly limited to this. Alternatively, a flat belt, V belt, V-ribbed belt, toothed belt, or the like may be used. Further, the rubber composition according to the embodiment is not limited to the transmission belt, and can be used for rubber products such as tires and hoses.

(Rubber composition)
Rubber compositions of Examples 1 to 15 and Comparative Examples 1 to 3 were prepared. Their configurations are also shown in Tables 1A and B.

<Example 1>
The sulfur-modified CR latex (manufactured by Tosoh Corporation) is mixed with 10 parts by mass of TEMPO-oxidized CNF (fiber diameter 3 nm to 4 nm) with respect to 100 parts by mass of the sulfur-modified CR of the rubber component therein, and the solvent is removed to remove sulfur. A master batch in which TEMPO-oxidized CNF was dispersed in CR was prepared. And in this masterbatch, with respect to 100 parts by mass of sulfur-modified CR of the rubber component, 22 parts by mass of FEF (manufactured by Seast SO Tokai Carbon Co.), para-aramid short fibers (manufactured by Technora Teijin Ltd., fiber length of 3.0 mm and fibers) An uncrosslinked rubber composition was obtained by blending and kneading 16 parts by mass), 5 parts by mass of plasticizer, 1 part by mass of stearic acid, 5 parts by mass of zinc oxide, and 5 parts by mass of magnesium oxide. A rubber composition obtained by crosslinking the rubber component by heating and pressurizing the uncrosslinked rubber composition was referred to as Example 1.

<Example 2>
A rubber composition having the same configuration as that of Example 1 was used in Example 2, except that the amount of TEMPO-oxidized CNF was 1 part by mass with respect to 100 parts by mass of the rubber component.

<Example 3>
A rubber composition having the same configuration as that of Example 1 was obtained as Example 3 except that the amount of TEMPO-oxidized CNF was 5 parts by mass with respect to 100 parts by mass of the rubber component.

<Example 4>
A rubber composition having the same configuration as that of Example 1 was used in Example 4 except that the amount of TEMPO-oxidized CNF was 20 parts by mass with respect to 100 parts by mass of the rubber component.

<Example 5>
A rubber composition having the same structure as Example 1 was used in Example 5 except that mercaptan-modified CR latex (B-30 manufactured by Tosoh Corporation) was used instead of sulfur-modified CR latex.

<Example 6>
A rubber composition having the same configuration as that of Example 1 was determined as Example 6 except that the amount of FEF was 5 parts by mass with respect to 100 parts by mass of the rubber component.

<Example 7>
A rubber composition having the same configuration as that of Example 1 was used in Example 7 except that the amount of FEF was 10 parts by mass with respect to 100 parts by mass of the rubber component.

<Example 8>
A rubber composition having the same configuration as that of Example 1 was used in Example 8 except that the amount of FEF was 40 parts by mass with respect to 100 parts by mass of the rubber component.

<Example 9>
A rubber composition having the same configuration as that of Example 1 was used in Example 9, except that the amount of FEF was 60 parts by mass with respect to 100 parts by mass of the rubber component.

<Example 10>
A rubber composition having the same configuration as that of Example 1 was used in Example 10 except that ISAF (Seat 600 manufactured by Tokai Carbon Co., Ltd.) was used instead of FEF.

<Example 11>
A rubber composition having the same structure as that of Example 1 was used in Example 11 except that SRF (Seast 9 manufactured by Tokai Carbon Co., Ltd.) was used instead of FEF.

<Example 12>
A rubber composition having the same structure as that of Example 1 was used in Example 12 except that mechanical defibrated CNF (fiber diameter of several tens to several hundreds of nm) was blended in place of TEMPO-oxidized CNF.

<Example 13>
-TEMPO catalyzed oxidation-soft bleached kraft pulp thoroughly washed with hydrochloric acid and ion-exchanged water, then mixed with ion-exchanged water, and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) and NaBr was added and stirred. Next, an aqueous sodium hypochlorite solution was added to the pulp mixture, pH was adjusted, and stirring was continued. And the obtained pulp liquid mixture was filtered, and the residue was fully wash | cleaned with ion-exchange water. By this TEMPO catalytic oxidation treatment, the hydroxyl group at the C6 position in the cellulose molecule contained in the pulp was selectively oxidized to a carboxyl group.

-Protonation-The obtained TEMPO catalyst oxidized pulp was mixed with ion-exchanged water and stirred. Next, hydrochloric acid was added dropwise to the pulp mixture. And the obtained pulp liquid mixture was filtered, and the residue was fully wash | cleaned with ion-exchange water. By this protonation treatment, the carboxyl group introduced by TEMPO catalytic oxidation was protonated.

-Amination-The protonated pulp obtained was mixed with ion-exchanged water and stirred. Subsequently, the hexadecyl trimethyl ammonium hydroxide aqueous solution was dripped at the pulp liquid mixture. And the obtained pulp liquid mixture was filtered, and it dried, after washing | cleaning the residue sufficiently with ion-exchange water. By this amination treatment, a carboxyl group introduced by TEMPO catalytic oxidation and protonated by protonation treatment is neutralized with hexadecyltrimethylammonium hydroxide to form a salt, that is, hexadecyltrimethyl of a quaternary ammonium compound. Aminated with ammonium hydroxide.

-Defibration-After the dried pulp was added to toluene and dispersed with a bead mill, the pulp contained in the obtained dispersion was defibrated using a jet mill (manufactured by Joko). By this defibrating treatment, a dispersion was prepared in which hydrophobic CNF (fiber diameter 3 nm to 4 nm) aminated with hexadecyltrimethylammonium hydroxide, a quaternary ammonium compound, was dispersed in toluene.

A dispersion obtained by dispersing the hydrophobic CNF thus obtained in toluene and a toluene solution of EPDM (EP33, manufactured by JSR Corporation, ethylene content: 52% by mass, ENB content: 8.1% by mass) are used as EPDM100 as a rubber component. Mixing was performed so that the content of hydrophobized CNF relative to 5 parts by mass was 5 parts by mass, and toluene was removed to prepare a master batch in which hydrophobized CNF was dispersed in EPDM. And in this master batch, 50 parts by mass of FEF, 16 parts by mass of para-aramid short fiber, 5 parts by mass of plasticizer, 1 part by mass of stearic acid, 5 parts by mass of zinc oxide, co-crosslinking with respect to 100 parts by mass of EPDM of rubber component An uncrosslinked rubber composition was obtained by blending and kneading 10 parts by weight of an agent (Seiko Chemical Co., Ltd. High Cloth M) and 6 parts by weight of an organic peroxide crosslinking agent (Park Mill D, manufactured by Nippon Oil & Fats Co., Ltd.). A rubber composition obtained by heating and pressurizing the crosslinked rubber composition to crosslink the rubber component was designated as Example 13.

<Example 14>
A rubber composition having the same configuration as that of Example 13 except that the blending amount of hydrophobic CNF and the blending amount of FEF were 10 parts by mass and 35 parts by mass with respect to 100 parts by mass of the rubber component, respectively. did.

<Example 15>
A rubber composition having the same configuration as Example 13 except that the blending amount of hydrophobic CNF and the blending amount of FEF were 20 parts by mass and 15 parts by mass with respect to 100 parts by mass of the rubber component, respectively. did.

<Comparative Example 1>
Implemented except that hydrogenated nitrile rubber latex (ZLX-B manufactured by Nippon Zeon Co., Ltd.) was used instead of sulfur-modified CR latex, and 3 parts by weight of organic peroxide crosslinking agent was blended with respect to 100 parts by weight of rubber component. A rubber composition having the same configuration as in Example 1 was referred to as Comparative Example 1.

<Comparative example 2>
Implemented except that styrene butadiene rubber latex (manufactured by J-9049 JSR) was used instead of sulfur-modified CR latex and that 0.3 parts by weight of organic peroxide crosslinking agent was blended with respect to 100 parts by weight of rubber component. A rubber composition having the same configuration as in Example 1 was referred to as Comparative Example 2.

<Comparative Example 3>
A rubber composition having the same configuration as that of Example 1 except that FEF was not blended was designated as Comparative Example 3.

(Test method)
<Rubber hardness>
For each of Examples 1 to 15 and Comparative Examples 1 to 3, rubber hardness was measured using a type A durometer based on JIS K6253: 2012.

<Tensile properties>
For each of Examples 1 to 15 and Comparative Examples 1 to 3, the tensile strength and the elongation at break were measured in the line direction based on JISK6251: 2010.

<Viscoelastic properties>
For each of Examples 1 to 15 and Comparative Examples 1 to 3, the storage elastic modulus (E ′) and loss tangent (tan δ) in the anti-reverse direction at 25 ° C. and 100 ° C. were measured based on JISK6394: 2007. did. The measurement conditions were a dynamic strain of 1.0% and a frequency of 10 Hz. Further, the ratio of the freshly stored elastic modulus at 100 ° C to the freshly stored elastic modulus at 25 ° C was calculated.

<Belt characteristics>
Each of Examples 1 to 15 and Comparative Examples 1 to 3 was used as a rubber composition for forming a compressed rubber layer of the belt body so that the reverse direction is the belt length direction. A single cogged V-belt B1 having a configuration was produced.

-Crack resistance-
FIG. 2 shows a belt running test machine 20 for evaluating crack resistance.

The belt running test machine 20 includes a drive pulley 21 having a pulley diameter of 40 mm and a driven pulley 22 having a pulley diameter of 40 mm provided on the right side thereof. The driven pulley 22 is movably provided to the left and right so that an axial load (dead weight DW) can be applied.

The single cogged V-belt B1 using each of Examples 1 to 15 and Comparative Examples 1 to 3 is wound between the drive pulley 21 and the driven pulley 22 of the belt running test machine 20 and is moved to the right side with respect to the driven pulley 22. A belt tension was applied by applying an axial load of 600 N, and the driving pulley 21 was rotated at a rotational speed of 3000 rpm under an ambient temperature of 100 ° C. to run the belt. Then, the belt running was periodically stopped to visually check for the occurrence of cracks. The belt running time until the occurrence of cracks was confirmed was defined as the crack life. The maximum belt running time was 240 hours.

-Wear resistance and belt temperature-
FIG. 3 shows a belt running test machine 30 for evaluating wear resistance.

The belt running test machine 30 includes a driving pulley 31 having a pulley diameter of φ60 mm and a driven pulley 32 having a pulley diameter of 100 mm provided on the left side thereof. The driven pulley 32 is movably provided to the left and right so that an axial load (dead weight DW) can be applied.

For the single cogged V-belt B1 using each of Examples 1 to 15 and Comparative Examples 1 to 3, after measuring the belt mass, the belt is wound between the driving pulley 31 and the driven pulley 32 of the belt running test machine 30, and the driven pulley A belt load is applied by applying a shaft load of 700 N to the left side of the belt 32, a rotational load of 10 N · m is applied to the driven pulley 32, and the drive pulley 31 is rotated at a rotational speed of 4200 rpm at an ambient temperature of 50 ° C. The belt was rotated for 200 hours. The maximum temperature on the back of the belt during belt running was recorded as the belt temperature using a non-contact type thermometer. Further, the belt mass was measured again after running the belt. The belt mass after subtracting the belt mass from the belt mass before running the belt and dividing it by the belt mass before running the belt is calculated as the belt wear rate, and the wear index is calculated using the belt wear rate of Example 1 as 100. did.

(Test results)
Tables 2A and B show the test results.

According to Tables 2A and B, in Examples 1 to 15 in which predetermined amounts of CNF and FEF were blended with CR or EPDM, the storage elastic modulus at 100 ° C. with respect to the storage elastic modulus at 25 ° C. in the reverse direction. The ratio of the elastic modulus is as high as 0.75 or more, so that the temperature dependence of the freshly stored elastic modulus is small. Therefore, it is expected that the difference in the magnitude of deformation with temperature change is small, and the loss tangent at 25 ° C. is 0. .16 or less and the loss tangent at 100 ° C. is as low as 0.13 or less, and therefore heat generation in dynamic use is expected to be small. Further, in the belt characteristics, it can be seen that the crack-resistant life is as long as 86.4 hours or longer, and the wear index is as low as 100 or less except in Examples 6, 7, and 11 to 15. Furthermore, it can be seen that the belt temperature during belt running is as low as 100 ° C. or less, and therefore heat generation is small.

On the other hand, in Comparative Example 1 in which the rubber component is hydrogenated nitrile rubber and Comparative Example 2 in which the rubber component is styrene butadiene rubber, the storage elastic modulus at 100 ° C. relative to the storage elastic modulus at 25 ° C. in the reverse direction. The ratios of the two are low at 0.60, so the temperature dependence of the freshly stored elastic modulus is large, and therefore, it is expected that the difference in the magnitude of deformation with temperature change is large, and the loss tangent at 25 ° C. In both cases, the loss tangent at 0.18 and 100 ° C. is as high as 0.14 and 0.15, respectively. Further, in the belt characteristics, it can be seen that the crack resistance life is as short as 42 hours and 31 hours, respectively, and the wear index is as high as 103 and 195. Further, it can be seen that the belt temperatures during the belt running are as high as 102 ° C. and 104 ° C., respectively, and thus the heat generation is large.

In Comparative Example 3 in which no FEF was blended, the ratio of the fresh elastic modulus at 100 ° C. to the fresh elastic modulus at 25 ° C. in the reverse direction was 0.71, which is slightly lower than those in Examples 1 to 15. In addition, the loss tangent at 25 ° C. and 100 ° C. is as low as 0.069 and 0.049, respectively. Therefore, it is expected that the heat generation in dynamic use is small. Is 82.4 hours, which is slightly shorter than Examples 1 to 15, and the belt temperature during belt running is 84 ° C., which is the same level as in Examples 1 to 15. However, it can be seen that the wear index is as high as 205.

The present invention is useful in the technical field of rubber compositions and transmission belts using the rubber compositions.

B1 Single cogged V-belt B2 Double cogged V-belt 10 Belt body 11 Compression rubber layer 12 Stretch rubber layer 13 Adhesive rubber layer 14 Core wire 15 Inner reinforcing cloth 16 Outer reinforcing cloth 17 Inner cog 18 Outer cogs 20, 30 Belt running

test machines

21, 31

Drive pulley

22, 32 Drive pulley

Claims

A rubber composition in which cellulose nanofibers and carbon black are dispersed in a rubber component mainly composed of chloroprene rubber or ethylene-α-olefin elastomer,
The cellulose nanofiber content is 1 to 20 parts by mass with respect to 100 parts by mass of the rubber component, and the carbon black content is 5 to 60 parts by mass with respect to 100 parts by mass of the rubber component. A rubber composition having a mass part or less.
The rubber composition according to claim 1, wherein
A rubber composition wherein the main component of the rubber component is sulfur-modified chloroprene rubber.
The rubber composition according to claim 1, wherein
A rubber composition in which a main component of the rubber component is an ethylene / propylene / diene terpolymer.
The rubber composition according to any one of claims 1 to 3,
A rubber composition in which the cellulose nanofibers include TEMPO-oxidized cellulose nanofibers.
In the rubber composition according to any one of claims 1 to 4,
A rubber composition in which the carbon black contains FEF.
The rubber composition according to any one of claims 1 to 5,
The rubber composition whose sum of content of the said cellulose nanofiber and content of the said carbon black is 15 mass parts or more and 70 mass parts or less with respect to 100 mass parts of said rubber components.
In the rubber composition according to any one of claims 1 to 6,
The rubber composition whose ratio with respect to content of the said carbon black of content of the said cellulose nanofiber is 0.050 or more and 2.0 or less.
The rubber composition according to any one of claims 1 to 7,
A rubber composition having a cellulose nanofiber content less than the carbon black content.
The rubber composition according to any one of claims 1 to 8,
A rubber composition in which short fibers are further dispersed.
The rubber composition according to claim 9, wherein
A rubber composition in which the short fibers include para-aramid short fibers.
In the rubber composition according to claim 9 or 10,
The rubber composition whose sum of content of the said cellulose nanofiber and content of the said short fiber is 15 to 40 mass parts with respect to 100 mass parts of said rubber components.
The rubber composition according to any one of claims 9 to 11,
The rubber composition whose sum of content of the said cellulose nanofiber, content of the said carbon black, and content of the said short fiber is 30 to 90 mass parts with respect to 100 mass parts of said rubber components.
The rubber composition according to any one of claims 9 to 12,
The rubber composition whose ratio with respect to content of the said short fiber of content of the said cellulose nanofiber is 0.050 or more and 1.3 or less.
The rubber composition according to any one of claims 9 to 13,
A rubber composition in which the content of the cellulose nanofiber is less than the content of the short fiber.
A transmission belt in which at least a part of the belt body is formed of the rubber composition according to any one of claims 1 to 14.