JP5892055B2 - Rubber composition and conveyor belt - Google Patents

Description

  The present invention relates to a rubber composition and a conveyor belt having flame resistance and cold resistance.

  Conventionally, a rubber composition containing an organic cobalt salt and rosin has been used to bond a galvanized steel cord and a rubber composition (see, for example, Patent Document 1). In addition, when flame retardancy is imparted to the adhesive rubber, a flame retardant such as a halogen compound is added without using a halogen-based rubber, and chloroprene rubber (CR), which is a flame retardant rubber, is 100 parts by mass. It is known to do (see, for example, Patent Document 2).

  Patent Document 1 describes a rubber composition having excellent adhesion to a galvanized metal material. The rubber composition described in Patent Document 1 contains a predetermined amount of rosin or a rosin derivative, an organic cobalt salt, and an organic chlorine compound with respect to 100 parts by weight of sulfur vulcanizable rubber.

  Patent Document 2 describes a chloroprene-based adhesive rubber composition excellent in flame retardancy and heat resistance. The adhesive rubber composition described in Patent Document 2 contains a predetermined amount of organic acid cobalt salt, zinc oxide, sulfur, and 2-mercaptoimidazoline with respect to 100 parts by weight of chloroprene rubber.

Japanese Patent Laid-Open No. 11-21389 JP-A-8-59896

  However, the rubber composition to which a flame retardant is added without using the halogen-based rubber described in Patent Document 1 can maintain adhesiveness, but is not sufficiently considered for cold resistance and flame resistance. Moreover, in the adhesive rubber composition which mix | blended 100 mass parts of chloroprene rubber of patent document 2, although adhesiveness is maintained, cold resistance is not considered and there exists a possibility that it cannot be used in a cold region. Therefore, it is insufficient for use in a cold region or a use environment where flame retardancy is required, and there is room for further improvement.

  Thus, a rubber composition for metal bonding that has excellent adhesion to a galvanized steel cord, high flame retardancy, and excellent cold resistance has been desired.

  In view of the above problems, an object of the present invention is to provide a rubber composition and a conveyor belt that are excellent in adhesion to a galvanized steel cord and have improved flame retardancy and cold resistance.

The present invention includes the following (1) to (3).
(1) A rubber component containing butadiene rubber, chloroprene rubber and natural rubber, an organic cobalt salt, a rosin or rosin derivative, and an organic chlorine compound,
The content of the butadiene rubber is 5 parts by mass or more and 20 parts by mass or less in 100 parts by mass of the rubber component.
The content of the chloroprene rubber is 20 parts by mass or more and 65 parts by mass or less in 100 parts by mass of the rubber component.
The content of the organic cobalt salt is 0.2 parts by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the rubber component when the mass of the organic cobalt salt is converted to cobalt.
The content of the rosin or rosin derivative is 2 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the rubber component.
Content of the said organic chlorine compound is 5 to 35 mass parts with respect to 100 mass parts of said rubber components, The rubber composition characterized by the above-mentioned.
(2) The rubber composition according to (1), wherein the numerical value A calculated by the following formula (1) is 83 parts by mass or less with respect to 100 parts by mass of the rubber component.
A = mass part of content of chloroprene rubber × 0.8 + mass part of content of organochlorine compound × 1.5 + mass part of content of rosin or rosin derivative × 2.5 Formula (1)
(3) A conveyor belt comprising a composite obtained by vulcanizing a rubber composition containing the rubber composition according to (1) or (2) above and a galvanized steel cord.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in adhesiveness with the galvanized steel cord, and can improve a flame retardance and cold resistance.

FIG. 1 is a cross-sectional perspective view of a conveyor belt according to an embodiment of the present invention.

  The present invention will be described in detail below. The present invention is not limited by the following modes for carrying out the invention (hereinafter referred to as embodiments). In addition, constituent elements in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those in a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be appropriately combined.

<Rubber composition>
A rubber composition according to the present embodiment (hereinafter referred to as “composition of the present embodiment”) includes a rubber component including butadiene rubber (BR), chloroprene rubber (CR), and natural rubber (NR), and organic cobalt. Salt, rosin or rosin derivative, and organochlorine compound.

(Rubber component)
As the rubber component contained in the composition of the present embodiment, rubber capable of sulfur vulcanization is used. The rubber that can be sulfur vulcanized is a rubber that can be vulcanized using sulfur, such as natural rubber, synthetic rubber, or a mixture thereof, and examples thereof include diene rubber. Specific examples of the diene rubber include natural rubber, isoprene rubber (IR), various butadiene rubbers (BR), 1,2-butadiene rubber, various styrene-butadiene copolymer rubbers (SBR), and acrylonitrile. Examples thereof include butadiene copolymer rubber (NBR), chloroprene rubber, butyl rubber (IIR), and ethylene-propylene-diene rubber (EPDM). These rubber components can be used alone or in combination of two or more.

  Among these rubbers, butadiene rubber, chloroprene rubber, and natural rubber are included because they are excellent in adhesiveness, flame retardancy, and cold resistance.

  The butadiene rubber preferably has a mass average molecular weight (Mw) of 400,000 or more, more preferably 450,000 or more. When the weight average molecular weight is within this range, the tensile strength and elongation at break in the rubber composition after vulcanization are further improved. In addition, a mass average molecular weight is a mass average molecular weight (polystyrene conversion) measured by gel permeation chromatography (Gel permeation chromatography (GPC)), and it is preferable to use tetrahydrofuran (THF) as a solvent for the measurement. Commercially available products can be used as the butadiene rubber, and specific examples include Nipol BR1220 and Nipol BR1250H manufactured by Nippon Zeon Co., Ltd.

  Examples of the chloroprene rubber include sulfur-modified (G) type, non-sulfur-modified (W) type, and high crystal type, and various known chloroprene rubbers can be used. As the chloroprene rubber, commercially available products can be used. Specifically, for example, Neoprene GRT and Neoprene WRT manufactured by Showa Denko DuPont, Denka Chloroprene PM-40 and S-41 manufactured by Denki Kagaku Kogyo Co., Ltd., etc. Can be mentioned.

  The natural rubber is a polymer having a structure in which cis-1,4-polyisoprene is bonded to the head and tail, and a commonly used natural rubber can be used. As the natural rubber, commercially available products can be used, and specific examples include TSR-20, RSS # 3, and the like.

  The content of butadiene rubber in the rubber component is 5 parts by mass or more and 20 parts by mass or less, preferably 5 parts by mass or more and 15 parts by mass or less, in 100 parts by mass of the rubber component of the present embodiment. Moreover, content of the chloroprene rubber in the said rubber component is 20 to 65 mass parts in 100 mass parts of rubber components of this embodiment, Preferably it is 25 to 60 mass parts. The content of the natural rubber in the rubber component is the remaining amount obtained by subtracting the total content of the butadiene rubber and chloroprene rubber from 100 parts by mass of the rubber component of the present embodiment, that is, 15 parts by mass or more. 75 parts by mass or less, preferably 25 parts by mass or more and 70 parts by mass or less.

  If the content of butadiene rubber, chloroprene rubber and natural rubber is within the above ranges, flame retardancy and cold resistance can be improved while maintaining the adhesion of the composition of the present embodiment. Further, the tensile strength and elongation at break, which are physical properties after vulcanization of the composition of the present embodiment, are improved.

<Organic cobalt salt>
The organic cobalt salt contained in the composition of the present embodiment is not particularly limited as long as it is generally used as a liquid phase oxidation catalyst and is conventionally known. The organic cobalt salt is a method in which a cobalt acetate solution is added to an alkali soap solution of the corresponding organic acid and subjected to metathesis precipitation, a method in which the organic acid and cobalt (II) oxide are heated and melted, or a cobalt sulfate or cobalt nitrate solution in the organic acid benzine solution. It can obtain by the method of adding the aqueous solution of this. Specifically, as the organic cobalt salt, for example, cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt orthoborate, cobalt octylate, cobalt versatate, cobalt palmitate, cobalt rosinate, cobalt propionate, or A cobalt boron complex etc. can be mentioned. Among these, it is preferable to use cobalt naphthenate, cobalt neodecanoate, cobalt boron complex, and the like because the adhesiveness is further improved. Commercially available products can be used as the organic cobalt salt, and specific examples include 10% cobalt naphthenate manufactured by Dainippon Ink & Chemicals, Inc.

  The content of the organic cobalt salt is 0.2 parts by mass or more and 1.0 part by mass or less, preferably 0.3 parts by mass with respect to 100 parts by mass of the rubber component when the mass of the organic cobalt salt is converted to cobalt. The amount is 0.7 parts by mass or less. When the content of the organic cobalt salt is within the above range, the adhesiveness (with rubber) to the galvanized steel cord becomes good. In addition, when the content of the organic cobalt salt is less than 0.2 parts by mass, the adhesion to the galvanized steel cord and the moisture-resistant adhesion deteriorate, and when it exceeds 1.0 parts by mass, the aging resistance of the rubber composition deteriorates. Therefore, it is not preferable. In particular, the content of the organic cobalt salt is preferably 0.2 parts by mass or more and 1.0 part by mass or less from the viewpoint of achieving both adhesiveness and moisture-resistant adhesion and rubber physical properties.

<Rosin>
The rosin contained in the composition of this embodiment is a kind of natural resin also called pine resin. Examples of rosin derivatives include gum rosin, wood rosin extracted from pine wood with a solvent, tall oil rosin, polymers of these rosins, disproportionated rosin, maleated rosin, aldehyde-modified rosin, hydrogenated rosin, and their rosin derivatives. Examples include processed products. As the rosin and rosin derivative, known ones generally used as a tackifier can be used. As the rosin or rosin derivative, commercially available products can be used. Specifically, for example, gum rosin and wood rosin manufactured by Arakawa Chemical Industries, Ltd., tall oil rosin manufactured by Harima Kasei Kogyo Co., Ltd., hydrogenated by Hercules Examples include rosin.

  The content of rosin or rosin derivative is 2 parts by mass or more and 9 parts by mass or less, and preferably 3 parts by mass or more and 7 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the rosin or rosin derivative is within the above range, the adhesiveness (with rubber) to the galvanized steel cord is good, the roll processability is also good, and the cold resistance is improved. When the content of rosin or rosin derivative is less than 2 parts by mass, the moisture resistance adhesion between the rubber composition and the galvanized steel cord is not sufficient, and when it exceeds 9 parts by mass, the tackiness of the rubber composition increases and roll processing is performed. Sex worsens. In particular, the content of the rosin or rosin derivative is preferably 2 parts by mass or more and 9 parts by mass or less from the viewpoint of achieving both moisture-resistant adhesion and practical workability.

  Since the composition of this embodiment contains a rosin or a rosin derivative, it is excellent in adhesion to a galvanized steel cord and moisture-resistant adhesion. In addition, rosin and rosin derivatives are generally used as tackifiers, and by containing the rosin or rosin derivative, the composition of this embodiment has improved tackiness and adhesiveness to rolls. Rises at the same time. If the adhesiveness to the roll is too high, roll processability deteriorates. The roll processability refers to the tackiness and processability of the unvulcanized rubber composition fabric, and has the property of being easily formed into a sheet during processing (especially during roll rolling in a factory). Show.

<Organic chlorine compounds>
As the organic chlorine compound contained in the composition of the present embodiment, an organic chlorine compound generally used as a chlorine-based flame retardant can be used. As the organic chlorine compound, for example, a linear organic chlorine compound is preferably exemplified. Specific examples of the linear organic chlorine compound include chlorinated paraffin and chlorinated polyethylene. As these compounds, commercially available products can be used. For example, chlorinated paraffins having a chlorine content of 40% to 80% are commercially available, and any of them can be used. Examples of commercially available products include Toyoparax (chlorine content 70% by mass, manufactured by Tosoh Corporation), Empara 70S (chlorine content 70% by mass, manufactured by DOVER CHEMICAL COMPANY), and the like.

  The content of the organic chlorine compound is 5 parts by mass or more and 35 parts by mass or less, and preferably 5 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the rubber component. When the content of the organic chlorine compound is within the above range, the flame retardancy of the composition of the present embodiment is improved. In addition, when the content of the organic chlorine compound is less than 5 parts by mass, the adhesion is not stable, and when it exceeds 35 parts by mass, the composition of the present embodiment becomes excessively sticky and processing becomes difficult. In particular, from the viewpoint of achieving both adhesiveness and workability, the content of the organic chlorine compound is preferably 5 parts by mass or more and 35 parts by mass or less.

  The composition of the present embodiment contains an organochlorine compound, thereby improving the adhesiveness, particularly the initial adhesiveness. Furthermore, since the organochlorine compound imparts flame retardancy, the composition of this embodiment is excellent in both flame retardancy and cold resistance because it contains the organochlorine compound in an amount in the above range. For this reason, the steel cord conveyor belt manufactured using the composition of the present embodiment to be described later sufficiently satisfies the flame retardancy required for the steel cord conveyor belt used in the underground or the like, and in a cold region. Use is also possible.

  As described above, the composition of the present embodiment contains a predetermined amount of butadiene rubber, chloroprene rubber, and natural rubber in 100 parts by mass of the rubber component as essential components, and further contains an organic cobalt salt and rosin or rosin. By including a predetermined amount of each of the derivative and the organochlorine compound, it is possible to improve the flame retardancy and cold resistance as well as excellent adhesion to the galvanized steel cord.

  In addition, the composition of the present embodiment includes the above six essential components, and the numerical value A calculated by the following formula (1) with respect to 100 parts by mass of the rubber component is 83 parts by mass or less. preferable.

  The numerical value A calculated by the above formula (1) for the three components of chloroprene rubber, organochlorine compound and rosin is 83 parts by mass or less, preferably 50 parts by mass or more and 83 parts by mass or less, more preferably 60 parts by mass. Part to 83 parts by mass. The composition of this embodiment is galvanized by setting the numerical value A calculated by the above formula (1) for the three components of chloroprene rubber, organochlorine compound, and rosin to a predetermined blending amount that satisfies 83 parts by mass or less. In addition to excellent adhesion to steel cords, it is possible to improve flame retardancy and cold resistance, and to improve roll processability.

  The composition according to the present embodiment includes a phenol resin, a carboxyl group-containing liquid isoprene rubber (an isoprene polymer rubber produced by a solution polymerization method) in addition to the essential components described above within a range not impairing the object of the present invention. Etc.) may be included. In addition to these, various additives can be contained as required. Additives include, for example, fillers such as carbon black; vulcanization accelerators such as zinc white and stearic acid; vulcanization accelerators such as dibenzothiazyl disulfide; aging such as amines, phenols and waxes Inhibitors; sulfur; vegetable oil-based or mineral oil-based softeners; Two or more of these may be contained. The additives and the like can be kneaded by a general method to obtain a composition, which can be used for vulcanization or crosslinking. The blending amounts of these additives can be conventional conventional blending amounts as long as the object of the present embodiment is not violated.

  The method for producing the composition of the present embodiment includes, for example, 5 parts by mass or more and 20 parts by mass or less of butadiene rubber and 20 parts by mass or more and 65 parts by mass or less of chloroprene rubber in 100 parts by mass of the rubber component described above. When a predetermined amount of natural rubber is included as a rubber component and the mass of the organic cobalt salt is converted to cobalt, 0.2 parts by mass or more and 1.0 part by mass or less of rosin or a rosin derivative with respect to 100 parts by mass of the rubber component 2 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the component, and 5 parts by mass or more and 35 parts by mass or less of the organochlorine compound with respect to 100 parts by mass of the rubber component. A rubber composition is selected by appropriately selecting an agent, a vulcanization accelerator, an anti-aging agent, a softening agent and the like, adding a predetermined amount, and kneading at a predetermined temperature for a predetermined time using a roll mill or a Banbury mixer. How to obtain and the like.

  The rubber composition obtained above can be brought into close contact with a galvanized steel cord and sulfur vulcanized at a predetermined temperature for a predetermined time to form a composite of rubber and galvanized steel cord.

  As the steel cord to be bonded to the rubber composition described above, for example, a surface-treated steel cord galvanized can be used. As the plating method, electroplating, hot dipping, etc. can be applied. As a steel cord used for a conveyor belt or the like, it is preferable to use a galvanized steel cord from the viewpoint of rust prevention and durability. The strand diameter, the cord diameter, and the like of the galvanized steel cord can be appropriately selected according to their use when bonded to the rubber composition of the present embodiment to form a composite.

  As a method for adhering the composition of the present embodiment and the galvanized steel cord, for example, the rubber composition is adhered to the galvanized steel cord at a predetermined thickness, and press vulcanization is performed at 150 ° C. for 30 minutes, It can be a composite of a rubber composition and a galvanized steel cord. Since the composition of this embodiment is excellent in adhesion with a galvanized steel cord, it can be used for a material using a galvanized steel cord as a reinforcing material. Moreover, it is applicable not only to a steel cord but to a galvanized metal material.

  Since the composition of this embodiment has the above-described excellent characteristics, it is suitably used for the production of steel cord conveyor belts. Besides this, the production of hoses, crawler belts, marine hoses, tires, etc. Can be suitably used.

<Conveyor belt>
Next, the case where the composition of this embodiment is used for a conveyor belt will be described. FIG. 1 is a cross-sectional perspective view of a conveyor belt according to the present embodiment (hereinafter referred to as “conveyor belt of the present embodiment”). As shown in FIG. 1, the conveyor belt 10 includes cover rubber layers 11 a and 11 b, a coat rubber layer 12, and a galvanized steel cord 13. The conveyor belt 10 is, for example, a conveyor belt 10 in which a galvanized steel cord 13 covered with a coat rubber layer 12 is disposed between cover rubber layers 11a and 11b as a core body, and the coat rubber layer 12 is described above. A conveyor belt 10 including a composite obtained by vulcanizing a rubber composition and a galvanized steel cord 13. The method of vulcanizing the rubber composition containing the rubber composition of the present embodiment and the galvanized steel cord 13 into a composite is as described above.

  The surface layer of the conveyor belt 10 is composed of two layers of cover rubber layers 11a and 11b, and there is a coat rubber layer 12 in which a galvanized steel cord 13 is disposed as a core between the two layers of the cover rubber layers 11a and 11b. The coat rubber layer 12 is obtained by forming the rubber composition of the present embodiment into a sheet shape using a roll or the like, and then setting and vulcanizing the galvanized steel cord 13 as a core body. Then, the rubber composition and the surface of the galvanized steel cord 13 are firmly bonded to form the coated rubber layer 12. The coat rubber layer 12 serves as an adhesive layer between the galvanized steel cord 13 and the cover rubber 11, and also serves as a buffer material for the galvanized steel cord 13. For the cover rubber layer 11, a rubber composition containing a component excellent in flame resistance, heat resistance, cold resistance, oil resistance, abrasion resistance, or weather resistance is used depending on the application of the conveyor belt 10. Is preferred.

  Since the conveyor belt 10 of the present embodiment has the above-described configuration, it has excellent adhesiveness with the galvanized steel cord 13 and can improve flame resistance and cold resistance. Can have long-term reliability. Moreover, since the conveyor belt 10 of this embodiment has cold resistance and a flame retardance, it can be used also in a cold region where the outside air temperature is about −30 ° C., and can prevent a fire in the mine. it can.

  The manufacturing method of the conveyor belt 10 of this embodiment is not specifically limited, The method etc. which are used normally are employable. Specifically, first, the raw materials were kneaded using a roll, a kneader, a Banbury mixer, etc., then formed into a sheet shape for each cover rubber layer 11a, 11b using a roll or the like, and then obtained. A preferred example is a method in which the layers are laminated in a predetermined order so as to sandwich the coat rubber layer (reinforcing layer) 12 obtained as described above and pressed at a temperature of 140 to 170 ° C. for 10 to 60 minutes.

  As mentioned above, although the rubber composition and conveyor belt of this invention were demonstrated in detail, this invention is not limited to said example, You may perform various change and improvement in the range which does not deviate from the summary of this invention.

  Hereinafter, the composition according to the present embodiment will be specifically described with reference to examples. However, the composition according to the present embodiment is not limited to these.

<Preparation of rubber compositions (Examples 1-6, Comparative Examples 1-8)>
Each component shown in Table 1 is blended in the blending amount (part by mass) shown in the same table, and these are uniformly kneaded using a Banbury mixer. Examples 1 to 6 and Comparative Examples 1 to 8 shown in Table 1 Each rubber composition was prepared. Table 1 shows the amount of each component in each Example and Comparative Example.

  About each obtained rubber composition of each Example and a comparative example, adhesiveness, moisture-resistant adhesiveness, a flame retardance, cold resistance, and roll processability were evaluated by the method shown below. The results are shown in Table 1 below.

<Adhesiveness>
Each rubber composition of each Example and Comparative Example was closely adhered to a thickness of 15 mm on a galvanized steel cord having a diameter of 4.1 mm which was stored in a desiccator and subjected to dustproof and moistureproof treatment. A composite of the product and a steel cord was subjected to pressure vulcanization at 150 ° C. for 30 minutes to prepare a test body (rubber / galvanized steel cord composite). The steel cord was pulled out from each of the obtained specimens, and the adhesiveness was evaluated based on the rubber coverage (%). The pull-out test was performed according to DIN 22131. The rubber coverage was calculated as the ratio (%) of the rubber covered area remaining on the surface of the steel cord after drawing to the surface area of the steel cord. A rubber coverage of 70% or higher was judged good. The evaluation results are shown in Table 1 below. In addition, it means that adhesiveness is so good that a rubber coverage is high.

<Moisture resistance>
The part where the steel cord on the rubber surface of each test specimen is the same as that produced with the above adhesive properties is sealed with beeswax and left in a constant temperature and humidity chamber at a temperature of 50 ° C. and a relative humidity of 95% for 3 weeks. did. Thereafter, the steel cord was pulled out from each specimen, and the moisture-resistant adhesion was evaluated by the rubber coverage (%). The pull-out test was performed according to DIN 22131. A rubber coverage of 50% or higher was judged good. The evaluation results are shown in Table 1 below. In addition, it means that moisture-resistant adhesiveness is so good that a rubber coverage is high.

<Flame retardance>
Each rubber composition of each Example and Comparative Example obtained above was vulcanized for 30 minutes under a surface pressure of 3.0 MPa using a press molding machine at 150 ° C. to obtain a vulcanized sheet having a thickness of 2 mm. Produced. A test piece (150 mm × 60 mm) was cut out from this sheet, and the oxygen index was measured according to JIS K6269-1998. If the oxygen index was 32 or more, it was judged that the flame retardancy was good. The evaluation results are shown in Table 1 below. In addition, it means that a flame retardance is so high that the measured oxygen index is high.

<Cold resistance>
In accordance with “Low Temperature Impact Embrittlement Test” in JIS K6261-2006 “Vulcanized Rubber and Thermoplastic Rubber—How to Obtain Low Temperature Properties”, test pieces are prepared from the vulcanized rubber of each rubber composition and specified. The temperature at which 50% of the total number of specimens breaks (embrittlement temperature) was measured when impact bending was applied to the specimens under the above conditions. If the embrittlement temperature was −35 ° C. or lower, it was judged good. The evaluation results are shown in Table 1 below. In addition, it means that cold resistance is so high that the measured embrittlement temperature is low.

<Roll processability>
Each rubber composition of each of the Examples and Comparative Examples obtained above was passed through a roll heated to 40 ° C. with a gap of 2.0 mm, and the peelability from the roll was visually observed to roll workability. Evaluated. Roll workability was evaluated based on the following evaluation criteria. The evaluation results are shown in Table 1 below.
(Evaluation criteria)
A: There is no adhesion of the rubber composition to the roll surface. O: There is a slight adhesion of the rubber composition to the roll surface, but the sheet can be put out. Possible ×: Adhesion to the roll surface of the rubber composition is seen, and sheeting is difficult

Each component shown in Table 1 is as follows.
NR: natural rubber, TSR-20
SBR: Styrene-butadiene rubber, trade name “NIPOL 1502”, manufactured by Nippon Zeon Co., Ltd. CR1: Chloroprene rubber, sulfur-modified chloroprene rubber, trade name “Denka Chloroprene PM-40”, manufactured by Denki Kagaku Kogyo Co., Ltd. Chloroprene rubber, non-sulfur modified chloroprene rubber, trade name “Denka Chloroprene S-41”, manufactured by Denki Kagaku Kogyo Co., Ltd. • BR: butadiene rubber, trade name “Nipol BR1220”, manufactured by Nippon Zeon Co., Ltd. • Organochlorine compound: Chlorination Paraffin, chlorine content 70%, trade name “Empara 70S”, manufactured by DOVER CHEMICAL COMPANY • HAF carbon: carbon black, trade name “Niteron # 200”, manufactured by Tokai Carbon Co., Ltd. • Rosin: Gum rosin, Arakawa Chemical Industries, Ltd. Made ・ Organic Salt salt: Cobalt naphthenate, cobalt content 10%, manufactured by Dainippon Ink & Co., Ltd. ・ Zinc flower: Vulcanization accelerator, trade name “Zinc flower 3”, manufactured by Shodo Chemical Industry Co., Ltd. ・ Sulfur: Vulcanization Agent, oil-treated sulfur, manufactured by Hosoi Chemical Co., Ltd. ・ Value of Formula 1: For 100 parts by mass of rubber component, the following formula: [A = chloroprene rubber (CR) × 0.8 + organochlorine compound × 1.5 + rosin Value of numerical value A calculated by × 2.5]

  From the result shown in Table 1, in Examples 1-6, it was confirmed that all are excellent in adhesiveness, moisture-proof adhesiveness, a flame retardance, cold resistance, and roll processability.

  On the other hand, it was confirmed that Comparative Example 1 was inferior in flame retardancy because it did not contain chloroprene rubber, and inferior in moisture resistance adhesion because it did not contain rosin. Further, in Comparative Example 2, it was confirmed that the butadiene rubber was not included, so that the cold resistance was inferior, the chloroprene rubber content was inadequate, the flame retardancy was inferior, and the rosin was not included, and the adhesiveness and moisture resistance were inferior It was. Further, in Comparative Example 3, since butadiene rubber was not included, the cold resistance was inferior, and since rosin was not included, the adhesiveness and moisture-resistant adhesive were inferior. It was. Moreover, in Comparative Example 4, since rosin was not included, it was confirmed that the adhesiveness and moisture-resistant adhesiveness were inferior. Moreover, in the comparative example 5, since natural rubber was not included, it was confirmed that it is inferior to moisture-resistant adhesiveness. Further, in Comparative Example 6, it was confirmed that the content of the organic chlorine compound was excessive, so that the cold resistance was inferior, and because the value of Formula 1 exceeded 83, the roll processability was inferior. Further, in Comparative Example 7, it was confirmed that the rosin content was excessive, so that the cold resistance was inferior, and because the value of Formula 1 exceeded 83, the roll processability was inferior. Moreover, in Comparative Example 8, it was confirmed that the flame retardance was inferior because the content of the organic chlorine compound was insufficient.

  Therefore, a rubber composition containing a predetermined amount of butadiene rubber, chloroprene rubber, natural rubber as the remaining rubber component, and a predetermined amount of organic cobalt salt, rosin or rosin derivative, and organic chlorine compound in 100 parts by mass of the rubber component, While being excellent in adhesiveness with the galvanized steel cord, flame retardancy and cold resistance can be improved (see Examples 1 to 6).

  Moreover, it contains the above six essential components and is calculated by the following formula [A = chloroprene rubber × 0.8 + organochlorine compound × 1.5 + rosin × 2.5] with respect to 100 parts by mass of the rubber component. By blending the above three components so that the numerical value A is 83 parts by mass or less, roll processability can be further improved (see Examples 1 to 6).

  Therefore, the composition of the present embodiment is superior in adhesion to a steel cord plated with zinc as compared with a rubber composition used conventionally, and can improve flame retardancy and cold resistance. It has been found that it can be suitably used for manufacturing a cord conveyor belt.

10 Conveyor belt 11, 11a, 11b Cover rubber layer 12 Coated rubber layer 13 Steel cord (galvanized steel cord)

Claims (3)

A rubber component containing butadiene rubber, chloroprene rubber and natural rubber, an organic cobalt salt, a rosin or rosin derivative, and an organic chlorine compound,
The content of the butadiene rubber is 5 parts by mass or more and 20 parts by mass or less in 100 parts by mass of the rubber component.
The content of the chloroprene rubber is 20 parts by mass or more and 65 parts by mass or less in 100 parts by mass of the rubber component.
The content of the organic cobalt salt is 0.2 parts by mass or more and 1.0 part by mass or less with respect to 100 parts by mass of the rubber component when the mass of the organic cobalt salt is converted to cobalt.
The content of the rosin or rosin derivative is 2 parts by mass or more and 9 parts by mass or less with respect to 100 parts by mass of the rubber component.
Content of the said organic chlorine compound is 5 to 35 mass parts with respect to 100 mass parts of said rubber components, The rubber composition characterized by the above-mentioned. The rubber composition according to claim 1, wherein the numerical value A calculated by the following formula (1) is 83 parts by mass or less with respect to 100 parts by mass of the rubber component.
A = mass part of content of chloroprene rubber × 0.8 + mass part of content of organochlorine compound × 1.5 + mass part of content of rosin or rosin derivative × 2.5 Formula (1)   A conveyor belt comprising a composite obtained by vulcanizing a rubber composition according to claim 1 or 2 and a galvanized steel cord.

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