Rubber composition and rubber product

Abstract

This rubber composition contains a rubber component and a carbonic acid compound. The carbonic acid compound is at least one type selected from a carbonate metal and a hydrogen carbonate metal.

Description

Rubber compositions and rubber products

[0001] The present disclosure relates to a rubber composition and a rubber product.

[0002] This application claims priority based on Japanese Application No. 2023-220808 filed on December 27, 2023, and incorporates by reference all of the contents of the aforementioned Japanese application.

[0003] Patent Document 1 discloses a method for generating hydrogen and immobilizing carbon dioxide, characterized in that hydrogen is generated by applying a mechanical impact or stress to a metal body or a substance containing a low-valent metal and supplying water and carbon dioxide to the metal body, and the carbon dioxide is converted into and immobilized in a substance containing a carbonate of a high-valent metal.

[0004] Japanese Patent Application Laid-Open No. 2007-031169

[0005] The rubber composition of the present disclosure contains a rubber component and a carbonate compound, and the carbonate compound is at least one type selected from metal carbonates and metal hydrogen carbonates.

[0006] Fig. 1 is a cross-sectional schematic diagram of a rubber composition according to one embodiment of the present disclosure. Fig. 2 is a cross-sectional schematic diagram of a rubber product according to one embodiment of the present disclosure. Fig. 3 is an explanatory diagram of a pull-out test in an experimental example. Fig. 4 is a table summarizing the compounding ratios of the rubber compositions and evaluation results in the experimental example.

[0007] [Problem to be solved by the present disclosure]

[0008] In recent years, promoting carbon neutrality has been considered as a way to prevent global warming. One method that contributes to the promotion of carbon neutrality is to use materials that immobilize carbon dioxide.

[0009] An object of the present disclosure is to provide a rubber composition using a material in which carbon dioxide is immobilized.

[0010] [Effects of the present disclosure]

[0011] According to the present disclosure, a rubber composition using a material in which carbon dioxide is immobilized can be provided.

[0012] [Description of the embodiments of the present disclosure] First, the embodiments of the present disclosure will be listed and described. In the following description, the same or corresponding elements will be denoted by the same reference numerals, and the same description will not be repeated.

[0013] (1) A rubber composition according to one embodiment of the present disclosure includes a rubber component and a carbonate compound, and the carbonate compound is at least one selected from the group consisting of metal carbonates and metal bicarbonates.

[0014] The carbonate compound is a material formed by the reaction of carbon dioxide with a metal or the like, and is a material in which carbon dioxide is immobilized. Therefore, by including a carbonate compound in the rubber composition according to one embodiment of the present disclosure, it is possible to obtain a rubber composition using a material in which carbon dioxide is immobilized, and thus to obtain a rubber composition that can contribute to promoting (achieving) carbon neutrality.

[0015] Furthermore, when a rubber product manufactured using the rubber composition according to one embodiment of the present disclosure includes a reinforcing material, the rubber composition contains a carbonate compound, thereby improving adhesion between the reinforcing material and the rubber.

[0016] The carbonate compound also functions as a filler, and therefore, when the rubber composition contains the carbonate compound, the amount of rubber component used per unit volume can be reduced, thereby reducing costs.

[0017] (2) In (1), the carbonate compound may contain iron carbonate.

[0018] When a rubber product manufactured using the rubber composition according to one embodiment of the present disclosure includes a reinforcing material, the carbonic acid compound contains iron carbonate, and this particularly improves adhesion between the reinforcing material and the rubber.

[0019] In the past, in rubber products, cobalt alone or a cobalt compound containing the rare and expensive metal cobalt has been used to improve adhesion between reinforcing materials and rubber. However, according to research by the inventors of the present invention, iron carbonate has the effect of particularly improving adhesion between reinforcing materials and rubber. Therefore, by including iron carbonate in the carbonate compound, the amount of cobalt alone or a cobalt compound added can be reduced, thereby reducing costs.

[0020] Iron carbonate is a material that fixes carbon dioxide, and therefore, by including iron carbonate in the carbonate compound, the rubber composition according to one embodiment of the present disclosure can be a rubber composition that uses a material that fixes carbon dioxide, and can be a rubber composition that can contribute to promoting carbon neutrality.

[0021] (3) In (1) or (2), one or more selected from the group consisting of simple cobalt and cobalt compounds may be further included.

[0022] The rubber composition according to an embodiment of the present disclosure includes one or more selected from the group consisting of cobalt alone and cobalt compounds, thereby increasing the crosslink density of the rubber in a rubber product manufactured using the rubber composition. Furthermore, when the rubber product manufactured using the rubber composition according to an embodiment of the present disclosure includes a reinforcing material, the rubber composition includes one or more selected from the group consisting of cobalt alone and cobalt compounds, thereby increasing the adhesion between the reinforcing material and the rubber in the rubber product.

[0023] (4) A rubber product according to one embodiment of the present disclosure includes a vulcanizate of the rubber composition according to any one of (1) to (3).

[0024] A rubber product according to one embodiment of the present disclosure includes a vulcanizate of the rubber composition according to one embodiment of the present disclosure, and therefore includes a carbonate compound. Therefore, the rubber product according to one embodiment of the present disclosure includes a material that immobilizes carbon dioxide, making it a product that can contribute to promoting carbon neutrality. Furthermore, the carbonate compound contained in the rubber composition has the effect of enhancing adhesion to reinforcing materials and functions as a filler. Therefore, the rubber product according to one embodiment of the present disclosure has excellent adhesion to reinforcing materials, and can reduce the amount of rubber used per unit volume, thereby reducing costs.

[0025] (5) In (4), the vulcanizate may be contained only in part.

[0026] By partially including the vulcanizate of the rubber composition according to one embodiment of the present disclosure, the rubber product according to one embodiment of the present disclosure can be made into a rubber composite by combining it with other materials or components such as reinforcing materials, resin molded articles, vulcanizates of other rubber compositions, etc. Therefore, the rubber product can be easily given desired properties.

[0027] (6) In (4) or (5), a reinforcing material may be further included in the vulcanizate.

[0028] The rubber product according to one embodiment of the present disclosure includes a reinforcing material disposed in the vulcanizate, thereby enhancing the durability of the rubber product. Furthermore, the rubber composition used in producing the rubber product according to one embodiment of the present disclosure contains a carbonate compound, which functions to enhance adhesion between the reinforcing material and the rubber. Therefore, the rubber product according to one embodiment of the present disclosure includes a reinforcing material, which provides excellent adhesion between the reinforcing material and the rubber, resulting in a rubber product with particularly excellent durability.

[0029] (7) In any of (4) to (6), the object may be any one selected from a belt conveyor, a hose, and a tire.

[0030] A rubber product according to an embodiment of the present disclosure includes a vulcanizate of the rubber composition according to an embodiment of the present disclosure, and therefore includes a carbonate compound. Therefore, the rubber product according to an embodiment of the present disclosure includes a material that immobilizes carbon dioxide, and can be a product that can contribute to promoting carbon neutrality. In particular, since belt conveyors, hoses, and tires are commonly used products, using the rubber product according to an embodiment of the present disclosure as a belt conveyor or the like can particularly enhance its contribution to promoting carbon neutrality.

[0031] Furthermore, the carbonate compound contained in the rubber composition has the effect of increasing adhesion to reinforcing materials and functions as a filler. Reinforcing materials are often used in rubber products such as belt conveyors, hoses, and tires. Therefore, by using a rubber product according to one embodiment of the present disclosure as a belt conveyor or the like, it is possible to produce a product with excellent adhesion to reinforcing materials and excellent durability. Furthermore, the amount of rubber used per unit volume can be reduced, thereby reducing costs.

[0032] [Details of the embodiment of the present disclosure] Specific examples of a rubber composition and a rubber product according to one embodiment of the present disclosure (hereinafter referred to as "the present embodiment") will be described below with reference to the drawings. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Rubber composition] The rubber composition according to the present embodiment will be described below with reference to the drawings.

[0033] As shown schematically in FIG. 1 , a rubber composition 10 of this embodiment can contain a rubber component 11 and a carbonate compound 12 .

[0034] 1 is a diagram schematically illustrating a cross section of a rubber composition 10 according to this embodiment, and the cross-sectional shape of the carbonate compound 12 is not limited to a circle and may have any shape. Furthermore, the carbonate compound 12 does not need to be embedded in the rubber component 11, and a portion of the carbonate compound 12 may be exposed on the surface. The rubber component 11 may also be in the form of a plurality of granules or the like.

[0035] The rubber composition 10 of the present embodiment can be produced by mixing the rubber component 11 and the carbonate compound 12. The rubber composition 10 of the present embodiment may be produced by adding any additive to the rubber component 11 and the carbonate compound 12 as needed, and mixing them.

[0036] The rubber composition 10 of the present embodiment may be produced by kneading raw materials such as a rubber component and a carbonate compound, and further molding the mixture as needed. (1) Regarding the Rubber Component As the rubber component, various rubbers can be used depending on the rubber product produced using the rubber composition, and are not particularly limited.

[0037] As the rubber component, for example, one or more types selected from a rubber component group including natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), butadiene rubber (BR), ethylene-propylene-diene rubber (EPDM), chloroprene rubber (CR), butyl rubber (IIR), and acrylonitrile-butadiene rubber (NBR) can be used.

[0038] The rubber component may contain, for example, at least one selected from natural rubber and isoprene rubber in a proportion of 60% by mass or more, which can particularly increase the breaking strength of a rubber product produced using the rubber composition. The rubber component may contain at least one selected from natural rubber and isoprene rubber in a proportion of 70% by mass or more, or may contain 100% by mass.

[0039] Examples of rubber components to be used in combination with natural rubber or isoprene rubber include rubber components other than natural rubber and isoprene rubber from the above-mentioned rubber component group. (2) Carbonate Compound and Method for Producing Carbonate Compound (2-1) Carbonate Compound The carbonate compound 12 can be, for example, one or more selected from metal carbonates and metal hydrogen carbonates. The carbonate compound 12 may be a metal carbonate to increase purity.

[0040] The carbonate compound 12 is formed by a reaction between carbon dioxide and a metal or the like, and is a material in which carbon dioxide is immobilized. Therefore, by including the carbonate compound 12 in the rubber composition 10 of the present embodiment, it is possible to provide a rubber composition using a material in which carbon dioxide is immobilized, and it is possible to provide a rubber composition that can contribute to promoting carbon neutrality.

[0041] Furthermore, since the rubber composition 10 contains the carbonate compound 12, when a rubber product manufactured using the rubber composition of this embodiment contains a reinforcing material, the adhesion between the reinforcing material and the rubber can be improved.

[0042] The carbonate compound 12 also functions as a filler. Therefore, when the rubber composition 10 contains the carbonate compound 12, the amount of rubber component used per unit volume can be reduced, and costs can be reduced.

[0043] The metal carbonate may be, for example, a carbonate salt of one or more metals selected from alkali metals, Group 2 metals, and transition metals.

[0044] The metal carbonate may be one or more selected from iron carbonate, magnesium carbonate, and calcium carbonate, from the viewpoint of efficiently fixing carbon dioxide in the production process while reducing raw material costs. Among them, the metal carbonate may be iron carbonate, which can more easily and reliably increase the purity of the carbonate compound 12.

[0045] In this specification, alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).

[0046] Group 2 metals include beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

[0047] Transition metals include scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), lanthanum (La), cerium (Ce), and praseodymium (P). r), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au), mercury (Hg), and the like.

[0048] From the viewpoint of ease of handling, the metal bicarbonate may be a bicarbonate of one or more metals selected from alkali metals, Group 2 metals, and transition metals. From the viewpoint of efficiently fixing carbon dioxide in the production process while reducing raw material costs, the metal bicarbonate may be one or more selected from iron bicarbonate, magnesium bicarbonate, and calcium bicarbonate. In particular, the metal bicarbonate may be iron bicarbonate.

[0049] As the carbonate compound 12, any one of metal carbonates and metal hydrogen carbonates may be used alone, or two or more of them may be used in combination.

[0050] Carbonate compound 12 may contain iron carbonate or may be iron carbonate. When carbonate compound 12 contains iron carbonate, in the case where a rubber product manufactured using the rubber composition of the present embodiment contains a reinforcing material, adhesion between the reinforcing material and the rubber can be particularly improved.

[0051] In the past, in rubber products, cobalt alone or a cobalt compound containing the rare and expensive metal cobalt has been used to improve adhesion between reinforcing materials and rubber. However, according to research by the inventors of the present invention, iron carbonate has the effect of particularly improving adhesion between reinforcing materials and rubber. Therefore, by including iron carbonate in the carbonate compound, the amount of cobalt alone or a cobalt compound added can be reduced, thereby reducing costs.

[0052] Since iron carbonate is a material that fixes carbon dioxide, by including iron carbonate in carbonate compound 12, the rubber composition of this embodiment can be made into a rubber composition that uses a material that fixes carbon dioxide, and can be made into a rubber composition that can contribute to promoting carbon neutrality.

[0053] The carbonate compound 12 is obtained by bonding a metal or a metal compound in the form of a metal ion with a carbonate ion or a bicarbonate ion, and therefore may have a purity of 80% by mass or more. From the viewpoint of increasing the amount of fixed carbon dioxide while reducing impurities from being mixed into the rubber composition 10, the purity of the carbonate compound 12 may be 85% by mass or more, 90% by mass or more, 95% by mass or more, or 98% by mass or more.

[0054] The purity of the carbonate compound can be measured by quantitative analysis using X-ray diffraction method in accordance with JIS K 0131 (1996).

[0055] The form of the carbonate compound 12 is not particularly limited, but may be, for example, granular.

[0056] When a metal or metal compound is bonded in the form of a metal ion with a carbonate ion or a bicarbonate ion to produce the carbonate compound 12, the carbonate compound 12 is usually obtained as precipitated particles of a metal carbonate or a metal bicarbonate. The average particle size of the carbonate compound 12 can be controlled, for example, by the bubbling conditions during production.

[0057] The average particle size of the carbonate compound 12 is not particularly limited. The average particle size of the carbonate compound 12 may be, for example, 1 nm or more, because excessive control of the particle size of the carbonate compound 12 is not necessary and production costs can be reduced. The average particle size of the carbonate compound 12 may be 10 nm or more, 30 nm or more, or 50 nm or more.

[0058] Furthermore, the average particle diameter of the carbonate compound 12 may be 1500 nm or less, because this makes it easier to increase the purity of the carbonate compound 12, improves the handleability of the carbonate compound 12, and makes it easier to mix it with the rubber component 11, etc. The average particle diameter of the carbonate compound 12 may be 1200 nm or less, 1000 nm or less, or 800 nm or less.

[0059] The upper and lower limit values ​​of the numerical ranges described in this specification can be arbitrarily combined. Therefore, the upper and lower limit values ​​of the average particle diameter of the carbonate compound 12 can be arbitrarily combined. The average particle diameter of the carbonate compound 12 may be, for example, 1 nm or more and 1500 nm or less, 10 nm or more and 1200 nm or less, 30 nm or more and 1000 nm or less, or 50 nm or more and 800 nm or less.

[0060] In this specification, the average particle size means the particle size at 50% of the volume integrated value in the particle size distribution determined by a laser diffraction / scattering method.

[0061] The crystal structure of carbonate compound 12 is not particularly limited, and may have a crystal structure specific to each metal carbonate or metal bicarbonate, such as a triclinic structure, monoclinic structure, orthorhombic structure, hexagonal structure, trigonal structure, tetragonal structure, cubic structure, etc. For example, when carbonate compound 12 is iron carbonate or iron bicarbonate, carbonate compound 12 may have a trigonal structure.

[0062] When the carbonate compound 12 is in the form of particles, the shape of the particles is not particularly limited. When the carbonate compound 12 is iron carbonate or iron hydrogen carbonate, for example, the carbonate compound 12 may have a polygonal plate-like shape in plan view.

[0063] The compounding ratio of the carbonate compound 12 in the rubber composition 10 is not particularly limited. For example, the compounding ratio of the carbonate compound 12 per 100 parts by mass of the rubber component can be 0.5 parts by mass or more. By setting the compounding ratio of the carbonate compound 12 per 100 parts by mass of the rubber component to 0.5 parts by mass or more, the amount of fixed carbon dioxide can be particularly increased, and when a rubber product manufactured using the rubber composition contains a reinforcing material, the adhesion between the reinforcing material and the rubber can be improved. The compounding ratio of the carbonate compound 12 per 100 parts by mass of the rubber component can be 1 part by mass or more.

[0064] Furthermore, for example, the blending ratio of the carbonate compound 12 per 100 parts by mass of the rubber component can be 40 parts by mass or less. By blending the carbonate compound 12 per 100 parts by mass of the rubber component at 40 parts by mass or less, it is possible to increase the strength of a rubber product made from the rubber composition 10. The blending ratio of the carbonate compound 12 per 100 parts by mass of the rubber component may be 35 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less.

[0065] The upper and lower limits of the mixing ratio of the carbonate compound per 100 parts by mass of the rubber component can be arbitrarily combined. The mixing ratio of the carbonate compound per 100 parts by mass of the rubber component may be, for example, 0.5 parts by mass to 40 parts by mass, 1 part by mass to 35 parts by mass, 1 part by mass to 10 parts by mass, or 1 part by mass to 5 parts by mass.

[0066] The carbonate compound 12 may be partially or entirely disposed inside the rubber composition 10, or at least partially exposed on the surface of the rubber composition 10. (2-2) Method for Producing Carbonate Compound The method for producing the carbonate compound is not particularly limited, and the carbonate compound can be produced by reacting carbon dioxide with a metal or the like.

[0067] Therefore, the method for producing a carbonate compound of this embodiment can have, for example, the following reaction steps: (2-2-1) Reaction Step In the reaction step, a metal raw material, which is a metal or a metal compound, is reacted with carbonic acid or hydrogen carbonate to produce a carbonate compound.

[0068] In the reaction step, the method for reacting the metal raw material with carbonic acid or hydrogen carbonate is not particularly limited. For example, by placing a metal raw material, which is a metal or a metal compound, in a solution and supplying carbon dioxide to the solution, the carbon dioxide dissolved in the solution reacts with the metal raw material and is fixed as a metal carbonate or metal hydrogen carbonate. It is thought that the metal raw material placed in the solution becomes metal ions, and the carbon dioxide dissolved in the solution becomes carbonate ions or hydrogen carbonate ions, and the metal ions react with the carbonate ions or hydrogen carbonate ions to produce a carbonate compound.

[0069] Hereinafter, the reaction between a metal ion and a carbonate ion or a hydrogen carbonate ion will be shown in formulas (1) and (2) using the case where the metal ion is an iron ion, a magnesium ion, or a calcium ion as an example. In formulas (1) and (2), M represents an iron atom, a magnesium atom, or a calcium atom; M ２＋ means either a divalent iron ion, a magnesium ion, or a calcium ion. ２＋ (aq) + CO ３ ２－ (aq) = MCO ３ (aq)...(1) M ２＋ (aq) + 2HCO ３ － (aq)=M(HCO ３ ) ２(aq) ... (2) In the reaction step, the temperature of the solution used in the reaction between the metal raw material and carbon dioxide is not particularly limited and can be selected depending on the type of metal ion generated from the metal raw material. For example, when the metal ion is an iron ion, the temperature of the solution may be 50°C or higher and 100°C or lower, 60°C or higher and 90°C or lower, or 80°C or higher and 90°C or lower, from the viewpoint of promoting the reaction between the metal ion and carbonate ion or bicarbonate ion.

[0070] The solution that can be used in the reaction step will be described below. (Solution) The composition of the solution used in the reaction step in which the metal raw material is placed and carbon dioxide is supplied is not particularly limited, but it may contain water as a solvent, for example.

[0071] The pH value of the solution is not particularly limited and can be selected depending on, for example, the type of metal raw material.

[0072] For example, when one or more metals selected from iron, magnesium, and calcium are used as the metal, or when one or more metal compounds selected from oxides and hydroxides of iron, magnesium, and calcium are used as the metal compound, the pH value can be selected so as to increase the divalent metal ions in the solution. In this case, from the viewpoint of increasing the divalent metal ions in the solution, the pH value of the solution may be 6 or less, 5 or less, 4 or less, 3 or less, 2.5 or less, 2 or less, or 1.5 or less.

[0073] The pH value of the solution may be, for example, 0 or higher. (Additive Components) The solution may also contain any additive components. The solution may also contain, as the optional additive components, one or more selected from, for example, a dissolution promoter, a pH buffer, a salt for adjusting the pH value of the solution, a carbonation promoter, a solution adjuster, and the like.

[0074] The dissolution promoter can promote the dissolution of carbonate ions and bicarbonate ions. Examples of the dissolution promoter include carbonic anhydrase. Carbonic anhydrase dissolves bicarbonate ions (HCO ) in a solution. ３－The inclusion of a dissolution promoter in the solution tends to increase the amount of carbonate ions or bicarbonate ions in the solution, thereby improving the efficiency of the reaction to fix carbonate ions or bicarbonate ions.

[0075] pH buffers have the function of making it easier to maintain the pH value of a solution at a desired value, and examples of pH buffers include sodium tartrate, sodium acetate, sodium citrate, and sodium phosphate.

[0076] Examples of salts for adjusting the pH value of a solution include salts for lowering the pH value of a solution. Examples of salts for lowering the pH value of a solution include salts that exhibit acidity in solution. Examples of salts that exhibit acidity in solution, i.e., salts that exhibit acidity when dissolved in solution, include sodium hydrogen sulfate, ammonium hydrogen sulfate, sodium dihydrogen phosphate, iron(II) sulfate, and iron(II) chloride.

[0077] The carbonation accelerator can promote the reaction between metal ions and carbonate ions or bicarbonate ions. The form of the carbonation accelerator is not particularly limited and may be, for example, particulate. The carbonation accelerator can contain metal carbonate or metal bicarbonate as the main component, i.e., in the largest mass ratio. The carbonation accelerator can serve as seed crystals for carbonating metal ions. That is, the carbonation accelerator acts as a seed crystal to grow crystals of a carbonate compound, thereby promoting the reaction between metal ions and carbonate ions or bicarbonate ions. Furthermore, by serving as a seed crystal, the carbonation accelerator can prevent the metal or metal compound, which is the metal raw material, from being coated with metal carbonate or the like, and minimize the resulting decrease in the amount of metal ion elution.

[0078] The carbonation promoter may be disposed at an interval from the metal raw material supplied in the solution. By disposing the carbonation promoter at an interval from the metal raw material supplied in the solution, it is possible to easily recover the carbonate compound using the carbonation promoter as seed crystals.

[0079] The solution conditioner can increase the amount of metal ions eluted in the solution.

[0080] The solution conditioner may be at least one of a reducing agent, a sequestering agent, and a builder. The solution conditioner can prevent the oxidation of metal ions in the solution. Examples of reducing agents include polyphenols such as catechin and chlorogenic acid. Examples of sequestering agents include citric acid and gluconic acid. The builder may be one used as a cleaning aid. Examples of builders include carbonates, silicates, aluminosilicates, sulfates, carboxymethylcellulose (CMC), and the like.

[0081] When the metal source is iron, iron oxide, or iron hydroxide, the pH value of the solution and the potential of the metal source in the solution may be controlled within a range in which divalent iron ions or divalent iron hydroxide are stable in a potential-pH diagram. That is, the pH value of the solution and the potential of the metal source may be controlled so as to increase the content of divalent iron ions, divalent iron hydroxide, or the like in the solution. In particular, from the viewpoint of more easily producing iron carbonate or iron bicarbonate, the pH value of the solution and the potential of the metal or metal compound may be controlled within a range in which divalent iron ions are stable in a potential-pH diagram.

[0082] Methods for controlling the pH value of a solution include adding a pH buffer to the solution, or a salt for adjusting the pH value of the solution.

[0083] The potential of the metal source may be controlled by applying a voltage to the metal source.

[0084] Examples of a means for measuring the pH value of a solution include a pH meter and a pH indicator. Examples of a means for measuring the potential of a metal raw material include an ORP (Oxidation-Reduction Potential) meter. (2-2-2) Regarding the Carbon Dioxide Supplying Step and the Metal Raw Material Supplying Step The method for producing a carbonate compound of this embodiment may include any step other than the reaction step.

[0085] The method for producing a carbonate compound according to the present embodiment may also include a carbon dioxide supplying step, a metal raw material supplying step, and the like.

[0086] The order in which the carbon dioxide supplying step and the metal raw material supplying step are carried out is not particularly limited, and for example, the carbon dioxide supplying step may be carried out after the metal raw material supplying step, or the carbon dioxide supplying step may be carried out after the carbon dioxide supplying step. Furthermore, the metal raw material supplying step and the carbon dioxide supplying step may be carried out in parallel. (Carbon dioxide supplying step) In the carbon dioxide supplying step, carbon dioxide can be supplied to the solution.

[0087] The carbon dioxide supplied in the carbon dioxide supply step may be supplied in the form of a mixed gas with other gases, or may be supplied as carbon dioxide alone. Examples of the mixed gas of carbon dioxide and other gases include air.

[0088] By supplying carbon dioxide to the solution, carbonate ions (CO ３ ２－ ) and bicarbonate ions (HCO ３ － ) occurs.

[0089] In the carbon dioxide supplying step, carbon dioxide may be bubbled into the solution to promote dissolution of carbonate ions or bicarbonate ions into the solution. The step of bubbling carbon dioxide into the solution may be carried out simultaneously within the carbon dioxide supplying step, or may be carried out separately from the carbon dioxide supplying step and referred to as a carbon dioxide dissolution promoting step or the like.

[0090] The method for bubbling carbon dioxide into the solution is not particularly limited, and examples thereof include a method using a bubble generator capable of generating fine bubbles such as nanobubbles and microbubbles in the solution, an ultrasonic generator capable of generating cavitation bubbles, etc. (Metal Raw Material Supply Step) In the metal raw material supply step, a metal or a metal compound as a metal raw material can be supplied to the solution.

[0091] In the metal raw material supply step, the metal or metal compound raw material may be arranged so that it is at least partially covered with the solution, or so that it is entirely covered with the solution, i.e., soaked in the solution. In the metal raw material supply step, the solution may be placed on a transmitting member that transmits the solution, such as a cloth, and the metal raw material may be arranged so as to be in contact with the transmitting member.

[0092] In the metal raw material supplying step, metal or metal compounds are supplied to the solution, so that metal ions can be eluted into the solution.

[0093] The metal raw material may be, for example, one or more metals selected from alkali metals, Group 2 metals, and transition metals, or one or more metals selected from iron, magnesium, and calcium. The metal may also be an alloy.

[0094] The metal compound serving as the metal source may be, for example, an oxide or hydroxide containing one or more selected from alkali metals, Group 2 metals, and transition metals. The metal compound may be an oxide or hydroxide containing one or more selected from iron, magnesium, and calcium. One type of metal source may be used alone, or two or more types may be used in combination.

[0095] The metal source may be derived from steel mill dust or steel scrap.

[0096] Examples of steel dust include scale generated by cutting iron materials. Using metal raw materials derived from steel dust and iron scrap can reduce the procurement costs of metal raw materials. Furthermore, because steel dust and iron scrap have traditionally been treated as waste, using them as metal raw materials can reduce the burden on the natural environment.

[0097] The metal raw material may be in the form of a lump or particles, and the shape and size of the metal raw material can be selected depending on the conditions for producing the carbonate compound, etc.

[0098] From the viewpoint of reducing the cost required for controlling the particle size, the average particle size of the metal raw material may be, for example, 1 μm or more, 10 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more.

[0099] From the viewpoint of promoting the elution of metal ions into the solution and promoting the reaction of the metal ions with carbonate ions or bicarbonate ions in the solution, the average particle size of the metal raw material may be 10,000 μm or less, 5,000 μm or less, 3,000 μm or less, 1,000 μm or less, 500 μm or less, 150 μm or less, 120 μm or less, or 100 μm or less.

[0100] The upper and lower limit values ​​of the average particle diameter of the metal raw material can be arbitrarily combined. The average particle diameter of the metal raw material may be, for example, 1 μm or more and 10,000 μm or less, 10 μm or more and 5,000 μm or less, 20 μm or more and 3,000 μm or less, 30 μm or more and 1,000 μm or less, 40 μm or more and 500 μm or less, 40 μm or more and 150 μm or less, 40 μm or more and 120 μm or less, or 40 μm or more and 100 μm or less. (3) Optional Additive Components The rubber composition 10 of this embodiment may contain optional additive components in addition to the rubber component 11 and the carbonate compound 12. (3-1) Cobalt Element, Cobalt Compound The rubber composition of this embodiment may further contain one or more selected from the group consisting of cobalt element and cobalt compounds.

[0101] The rubber composition of the present embodiment contains one or more selected from simple cobalt and cobalt compounds, thereby increasing the crosslink density of a rubber product manufactured using the rubber composition. Furthermore, when the rubber product manufactured using the rubber composition of the present embodiment contains a reinforcing material, the rubber composition contains one or more selected from simple cobalt and cobalt compounds, thereby increasing the adhesion (adhesion) between the reinforcing material and the rubber in the rubber product.

[0102] Cobalt itself and cobalt compounds may function as vulcanization accelerators, processing aids, and the like.

[0103] The cobalt compound may be any compound containing cobalt, and examples thereof include organic acid cobalt and inorganic acid cobalt.

[0104] The organic cobalt salt may be, for example, one or more selected from cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tallate, etc. The organic cobalt salt may be a composite salt in which part of the organic acid is replaced with boric acid.

[0105] When a rubber product manufactured using the rubber composition contains a reinforcing material, the rubber composition contains an organic cobalt acid, which can particularly improve the initial adhesive performance between the reinforcing material and the rubber in the rubber product. The initial adhesive performance means the adhesive performance between the reinforcing material and the rubber immediately after vulcanization.

[0106] As the inorganic acid cobalt, for example, one or more selected from cobalt chloride, cobalt sulfate, cobalt nitrate, cobalt phosphate, and cobalt chromate may be used.

[0107] When the rubber composition of this embodiment contains one or more selected from simple cobalt and cobalt compounds, the content thereof is not particularly limited, but can be, for example, a content of 0% by mass or more and 100% by mass or less of carbonate compound 12, based on the blending amount of the carbonate compound. By including simple cobalt or the like in an amount of 0% by mass or more and 100% by mass or less of carbonate compound 12, the crosslink density in the rubber product can be increased, improving adhesion between the reinforcing material and the rubber, while reducing the amount of cobalt added, thereby reducing the cost of the rubber composition. (3-2) Vulcanization Accelerator The rubber composition of this embodiment can also contain a vulcanization accelerator.

[0108] The rubber composition of this embodiment may also contain a sulfenamide-based vulcanization accelerator, such as N,N'-dicyclohexyl-2-benzothiazolylsulfenamide, N-cyclohexyl-2-benzothiazolylsulfenamide, N-tert-butyl-2-benzothiazolylsulfenamide, or N-oxydiethylene-2-benzothiazolylsulfenamide. Furthermore, the rubber composition of this embodiment may also contain, as a vulcanization accelerator, a thiazole-based accelerator such as 2-mercaptobenzothiazole or di-2-benzothiazolyl disulfide, or a thiuram-based accelerator such as tetrabenzyl thiuram disulfide, tetramethyl thiuram disulfide, tetraethyl thiuram disulfide, tetrakis(2-ethylhexyl)thiuram disulfide, or tetramethyl thiuram monosulfide. (3-3) Sulfur The rubber composition of this embodiment may also contain sulfur.

[0109] The sulfur is not particularly limited, but for example, sulfur generally used as a vulcanizing agent in the rubber industry can be used.

[0110] The sulfur content of the rubber is not particularly limited, and may be, for example, 5 parts by mass or more and 8 parts by mass or less per 100 parts by mass of the rubber component.

[0111] By adjusting the proportion of sulfur to 5 parts by mass or more per 100 parts by mass of the rubber component, the crosslink density of the resulting rubber can be increased. Furthermore, when the rubber product contains a reinforcing material, the adhesion between the reinforcing material and the rubber can be improved.

[0112] Furthermore, by setting the ratio of sulfur to 8 parts by mass or less per 100 parts by mass of the rubber component, the sulfur can be dispersed particularly uniformly in the rubber and the occurrence of blooming can be reduced. (3-4) Other Additives The rubber composition of the present embodiment can also contain well-known additives for rubber, such as a reinforcing agent (carbon black, silica, etc.), wax, and antioxidant.

[0113] The rubber composition of this embodiment may also contain a metal raw material that is a raw material for the carbonate compound. By containing a metal raw material in the rubber composition of this embodiment, carbon dioxide can also be immobilized after the rubber composition is formed. When the rubber composition of this embodiment contains a metal raw material, the materials described in the method for producing a carbonate compound can be used as the metal raw material. The rubber composition of this embodiment may contain, as the metal raw material, one or more selected from the oxides and hydroxides of iron, magnesium, and calcium, for example. [Rubber Product] The rubber product of this embodiment may contain a vulcanizate of the rubber composition according to one aspect of the present disclosure.

[0114] The rubber product of this embodiment contains a vulcanizate of the rubber composition according to one aspect of the present disclosure, and therefore contains a carbonate compound. Therefore, the rubber product of this embodiment contains a material that immobilizes carbon dioxide, making it a product that can contribute to promoting carbon neutrality. Furthermore, the carbonate compound contained in the rubber composition has the effect of enhancing adhesion to reinforcing materials and functions as a filler. Therefore, the rubber product of this embodiment has excellent adhesion to reinforcing materials, and the amount of rubber used per unit volume can be reduced, resulting in cost savings.

[0115] The vulcanization conditions for producing the rubber product of this embodiment are not particularly limited, and can be selected depending on the properties required of the rubber product.

[0116] The shape of the rubber product of the present embodiment is not particularly limited, and it may have a shape depending on the application.

[0117] The rubber product of the present embodiment may be formed solely from a vulcanizate of the rubber composition according to one aspect of the present disclosure.

[0118] The rubber product of the present embodiment may contain only a portion of the vulcanizate of the rubber composition according to one aspect of the present disclosure, i.e., the rubber product of the present embodiment may contain other materials, components, etc. in addition to the vulcanizate of the rubber composition according to one aspect of the present disclosure.

[0119] By partially including the vulcanizate of the rubber composition according to one aspect of the present disclosure, the rubber product of the present embodiment can be made into a rubber composite by combining it with other materials or components such as reinforcing materials, resin molded articles, vulcanizates of other rubber compositions, etc. Therefore, the rubber product can be easily given desired properties.

[0120] For example, as shown in FIG. 2, the rubber product 20 of this embodiment may further include a reinforcing material 22 disposed in the vulcanizate 21.

[0121] In FIG. 2, the shape of the reinforcing material 22 is not particularly limited, but may be, for example, linear (cord-like) in shape.

[0122] The arrangement of the reinforcing members 22 in the rubber product 20 is not particularly limited and can be selected depending on the properties required of the rubber product 20. For example, as shown in Fig. 2, the reinforcing members 22 can be arranged so that a plurality of reinforcing members 22 are aligned and embedded in the vulcanizate 21. In Fig. 2, the longitudinal directions of the plurality of reinforcing members 22 are arranged along the Z axis in Fig. 2, and the plurality of reinforcing members 22 are arranged along the X axis.

[0123] The reinforcing material 22 is not particularly limited, but may include one or more types selected from organic fiber reinforcing materials, carbon fiber reinforcing materials, and metal reinforcing materials.

[0124] The organic fiber reinforcing material may be one or more selected from nylon fiber, polyester fiber, rayon fiber, and aramid fiber. The nylon fiber may be one or more selected from nylon 6 fiber and nylon 66 fiber.

[0125] An example of a metal reinforcing material is a steel cord. The steel cord may be a twisted wire or a solid wire. When the steel cord is a solid wire, the steel cord may have a circular cross section or may be processed to have a cross section other than a circular shape.

[0126] The rubber product 20 of this embodiment includes the reinforcing material 22 disposed in the vulcanizate 21, thereby increasing the durability of the rubber product 20. Furthermore, the rubber composition used in producing the rubber product of this embodiment contains a carbonate compound, which has the function of increasing the adhesion between the reinforcing material 22 and the rubber. Therefore, the rubber product 20 of this embodiment includes the reinforcing material 22, which provides excellent adhesion between the reinforcing material 22 and the rubber, resulting in a rubber product 20 that is particularly excellent in durability.

[0127] The use of the rubber product of this embodiment is not particularly limited, and may be any rubber product selected from, for example, a belt conveyor, a hose, and a tire.

[0128] The rubber product of this embodiment contains a vulcanizate of the rubber composition according to one aspect of the present disclosure, and therefore contains a carbonate compound. Therefore, the rubber product of this embodiment contains a material that immobilizes carbon dioxide, making it a product that can contribute to promoting carbon neutrality. In particular, since belt conveyors, hoses, and tires are commonly used products, using the rubber product of this embodiment as one of these belt conveyors can particularly enhance its contribution to promoting carbon neutrality.

[0129] Furthermore, the carbonate compound contained in the rubber composition has the effect of increasing adhesion to reinforcing materials and functions as a filler. Reinforcing materials are often used in rubber products such as belt conveyors, hoses, and tires. Therefore, by using the rubber product of this embodiment as a belt conveyor or the like, it is possible to obtain a product with excellent adhesion to reinforcing materials and excellent durability. Furthermore, the amount of rubber used per unit volume can be reduced, thereby reducing costs.

[0130] Although the embodiments have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the claims.

[0131] Specific examples will be given below for explanation, but the present invention is not limited to these examples. (Evaluation Method) First, the evaluation method of the rubber compositions and rubber products prepared in the following experimental examples will be explained. (1) Pull-out Test Using the rubber composition produced in each experimental example, a test specimen 30, which is the rubber product shown in Figure 3, was prepared, and a pull-out test was performed in accordance with the rubber adhesion test of JIS G 3510 (1992).

[0132] When preparing the test specimen 30, a steel cord having a 1x2 structure and made by twisting two wires together was used as the reinforcing material 31, and each wire had a brass-plated film on its surface.

[0133] The test specimen 30 was manufactured by sandwiching parallel-aligned reinforcing materials 31 between the rubber compositions prepared in each experimental example using a mold, pressurizing the mixture, and then heating it at 160° C. for 15 minutes to vulcanize it. When manufacturing the test specimen 30, the rubber composition was arranged so that the embedding depth L31 of the reinforcing materials 31 in the vulcanizate 32 was 12.5 mm.

[0134] Then, one reinforcing material 31 was pulled by a tensile tester to evaluate the pull-out force. The evaluation result of Experimental Example 1 was set to 100, and the results are shown in the "Pull-out force" column in Figure 4 as relative values.

[0135] Furthermore, for the extracted reinforcing material 31, image processing was performed on the region that was disposed within the vulcanizate 32, and the percentage of the area to which the vulcanizate was attached was calculated and shown in the "coverage rate" column in Fig. 4. The coverage rate indicates a specific evaluated value (percentage).

[0136] The larger the pull-out force and coverage ratio, the better the adhesion between the reinforcing material 31 and the rubber contained in the vulcanizate 32. With regard to the pull-out force, a value of 80 or more indicates particularly excellent adhesion between the reinforcing material 31 and the rubber. (Experimental Examples) The experimental conditions will be explained below. Experimental Examples 1 and 2 are comparative examples, and Experimental Examples 3 and 4 are working examples. [Experimental Example 1] A rubber composition was produced by kneading the components so as to obtain the compounding ratio shown in Figure 4. The evaluation results are shown in Figure 4. [Experimental Example 2] A rubber composition was produced by kneading the components so as to obtain the compounding ratio shown in Figure 4.

[0137] In Experimental Example 2, the amount of cobalt stearate added was set to 0 parts by mass, and the amount of stearic acid added was increased instead. In addition, the curast curve (vulcanization curve) was measured, and the amount of CZ vulcanization accelerator added was adjusted so that Tc10, Tc50, and Tc90 were within ±10% of the evaluation values ​​for the rubber composition of Experimental Example 1. Tc10, Tc50, and Tc90 represent the 10% vulcanization time, 50% vulcanization time, and 90% vulcanization time, respectively.

[0138] The evaluation results are shown in Figure 4. [Experimental Example 3] (Regarding Rubber Composition) Each component was kneaded so as to have the compounding ratio shown in Figure 4, to produce a rubber composition.

[0139] In Experimental Example 3, the amount of cobalt stearate added was set to 1 part by mass, half that of Experimental Example 1, and the amount of stearic acid added was increased instead. In addition, the curast curve was measured, and the amount of CTP (N-cyclohexylthiophthalimide) (manufactured by Eishin Chemical Co., Ltd.), a retarder (scorch retarder), was adjusted so that Tc10, Tc50, and T90 were within ±10% of the evaluation values ​​for the rubber composition of Experimental Example 1.

[0140] In Experimental Example 3, 1.1 parts by mass of iron carbonate was blended. The blending ratio of cobalt stearate to iron carbonate was 91% by mass.

[0141] The evaluation results are shown in Figure 4. (Regarding Iron Carbonate) Iron carbonate used in this experiment was produced according to the following procedure.

[0142] Iron powder was placed in a glass reaction vessel, and water was poured into the vessel so that the iron powder was completely immersed (metal raw material supplying step).

[0143] The reaction vessel was then placed in an oil bath, and the temperature of the oil bath was adjusted to 80°C or higher and 90°C or lower. Furthermore, humidified carbon dioxide was bubbled into the water in the reaction vessel (carbon dioxide supply step). The bubbling rate was 200 mL / min. After maintaining this state for 4 days (reaction step), approximately 20 g of iron powder was removed from the reaction vessel and dried under reduced pressure to obtain iron carbonate. The purity of the iron carbonate measured by quantitative analysis using X-ray diffraction was 91% by mass.

[0144] To confirm the shape of the iron carbonate particles, structural observation was performed using an electron microscope (Gemini 450 manufactured by Carl Zeiss K.K.) at a magnification of 10,000 times, and the iron carbonate particles were found to be polygonal plate-like in plan view. The average particle diameter of the iron carbonate was 1 nm or more and 1,000 nm or less. [Experimental Example 4] A rubber composition was produced by kneading the components so as to obtain the ratios shown in Figure 4.

[0145] In Experimental Example 4, the amount of cobalt stearate added was set to 0 parts by mass, and the amount of stearic acid added was increased instead. The curast curve was measured, and the amount of CTP (a retarder (scorch retardant)) added was adjusted so that Tc10, Tc50, and T90 were within ±10% of the evaluation values ​​for the rubber composition of Experimental Example 1. The same iron carbonate as in Experimental Example 3 was added at 2 parts by mass. The ratio of cobalt stearate to iron carbonate was 0% by mass.

[0146] The evaluation results are shown in FIG.

[0147] 4, even in Experimental Examples 3 and 4, in which the amount of cobalt stearate added was reduced and a carbonate compound was blended, the pull-out force was 80 or more, confirming that high adhesion between the rubber and the reinforcing material was demonstrated. In particular, compared to the rubber composition of Experimental Example 2, in which no cobalt stearate was added, the rubber compositions of Experimental Examples 3 and 4 were confirmed to have pull-out forces equal to or greater than the rubber composition of Experimental Example 2, and to have higher coverage rates.

[0148] REFERENCE SIGNS LIST 10 Rubber composition 11 Rubber component 12 Carbonate compound 20 Rubber product 21 Vulcanizate 22 Reinforcing material 30 Test specimen 31 Reinforcing material L31 Embedding depth 32 Vulcanizate A Block arrow

Claims

1. A rubber composition containing a rubber component and a carbonate compound, wherein the carbonate compound is at least one selected from metal carbonates and metal hydrogen carbonates.

2. The rubber composition according to claim 1, wherein the carbonate compound contains iron carbonate.

3. The rubber composition according to claim 1 or 2, further containing at least one selected from elemental cobalt and cobalt compounds.

4. A rubber product containing a vulcanizate of the rubber composition according to any one of claims 1 to 3.

5. The rubber product according to claim 4, containing only a part of the vulcanizate.

6. The rubber product according to claim 4 or 5, further containing a reinforcing material disposed in the vulcanizate.

7. The rubber product according to any one of claims 4 to 6, which is any one selected from a belt conveyor, a hose, and a tire.

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