Vulcanizing agent composition and its manufacturing method, rubber composition manufacturing method, and vulcanized rubber manufacturing method

Abstract

The present invention provides a vulcanizing agent composition that includes sulfur as a vulcanizing agent component but still achieves substantially superior antistatic properties and combustion resistance. The present invention relates to a vulcanizing agent composition that includes sulfur and an alkyl ester of a saturated or unsaturated monovalent fatty acid.

Description

[Technical Field]

[0001] The present invention relates to a vulcanizing agent composition and a method for producing the same, a rubber composition and a method for producing the same, and a vulcanized rubber and a method for producing the same. [Background technology]

[0002] Sulfur is known as a vulcanizing agent used in rubber for tires and the like. Insoluble sulfur, a type of sulfur, is sulfur that is insoluble in carbon disulfide and is used as a vulcanizing agent for rubber. Compared to soluble sulfur, insoluble sulfur can suppress blooming, in which sulfur migrates to the rubber surface and precipitates during the process from mixing with rubber to completing vulcanization. For this reason, insoluble sulfur is widely used as a vulcanizing agent, particularly for radial tires (for example, Patent Document 1).

[0003] On the other hand, insoluble sulfur has low affinity with rubber, and therefore generally has poor dispersibility in rubber. This tendency is particularly pronounced when a large amount of insoluble sulfur is compounded into rubber, resulting in the formation of insoluble sulfur agglomerates, which leads to variations in the physical properties of the rubber after vulcanization and a deterioration in the quality of the rubber product. Therefore, in order to improve the dispersibility of insoluble sulfur when mixed into rubber, it is generally mixed with process oil such as naphthenic oil, aromatic oil, or paraffinic oil, and used as so-called oil-treated insoluble sulfur. Similarly, sulfur other than insoluble sulfur may also be mixed with process oil to improve dispersibility when used as a rubber vulcanizing agent.

[0004] In addition, sulfur is a Class 2 hazardous material (flammable solid), while the oils and fats used as process oils are Class 4 hazardous materials (flammable liquids). However, vulcanizing agent compositions obtained by mixing insoluble sulfur (Class 2 hazardous material) with naphthenic oil (Class 4 hazardous material) or by coating insoluble sulfur with naphthenic oil are non-hazardous solids. Thus, when sulfur is used as a rubber vulcanizing agent, it is sometimes used in a mixed state with process oil from the viewpoint of non-hazardous material.

[0005] Furthermore, sulfur such as insoluble sulfur is prone to static electricity, and becomes charged due to contact and friction between sulfur particles or contact and friction with a measuring device or kneading equipment during compounding into rubber, resulting in phenomena such as adhesion to the equipment and deterioration of flowability. Such adhesion to the measuring device, etc., leads to fluctuations in the sulfur compounding amount, and since it is necessary to resolve this, workability and productivity may decrease. In particular, when highly adhesive sulfur is used in an automatic measuring device, handling it is often difficult.

[0006] For example, Patent Document 1 describes that by adding a dicyclopentadiene resin to a vulcanizing agent composition (oil-treated product) in which insoluble sulfur and naphthenic process oil are mixed, it is possible to reduce the adhesion of the vulcanizing agent composition to equipment, etc. Patent Document 1 lists as examples of process oils rubber process oils such as vegetable oils (castor oil, rapeseed oil, linseed oil, cottonseed oil, soybean oil, palm oil, coconut oil, rosin pine oil, and tall oil), fatty acids, and fatty acid derivatives.

[0007] Furthermore, for example, Patent Document 2 describes an insoluble sulfur composition comprising insoluble sulfur, a surfactant containing sorbitan monolaurate as a main component, and process oil, and describes that the composition can improve adhesion to equipment and fluidity by preventing static electricity, thereby improving workability during rubber mixing.

[0008] On the other hand, Patent Document 3 lists powdered sulfur, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, and non-staining sulfur donors as examples of sulfur used as a vulcanizing agent in hydrogenated chloroprene rubber compositions. Processing aids for rubber molding can be blended into the hydrogenated chloroprene rubber composition as needed, and lists fatty acid esters such as butyl stearate as examples of such processing aids.

[0009] In recent years, there has also been a demand for sustainability, such as using recycled and biomass raw materials as raw materials for tires, in order to achieve carbon neutrality. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] WO2018 / 189878 issue [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-268240 [Patent Document 3] Japanese Patent Application Laid-Open No. 2003-313367 Summary of the Invention [Problem to be solved by the invention]

[0011] The inventors of the present invention have conducted extensive research into a vulcanizing agent composition containing a mixture of insoluble sulfur and a vegetable oil (soybean oil, rapeseed oil, linseed oil, palm oil) as a process oil, and have found the following new problems:

[0012] Vulcanizing agent compositions using vegetable oil as the process oil had high electrostatic charge and burned for a much longer period of time when ignited than vulcanizing agent compositions using naphthenic oil as the process oil. The result of burning for a longer period of time when ignited was different from what would be expected, since the flash point of naphthenic oil is approximately 180°C, while the flash point of vegetable oil is approximately 320°C, and was an unexpected issue in vulcanizing agent compositions that use vegetable oil as the process oil with an eye toward sustainability.

[0013] An object of the present invention is to provide a vulcanizing agent composition that contains sulfur as a vulcanizing agent component and yet has sufficiently excellent antistatic properties and flame resistance, and a method for producing the same. Specifically, an object of the present invention is to provide a vulcanizing agent composition that contains sulfur as a vulcanizing agent component, but that has reduced adhesion to equipment and a short burning duration when ignited, resulting in high safety.

[0014] Another object of the present invention is to provide a rubber composition containing the vulcanizing agent composition and a method for producing the same, as well as a vulcanized rubber of the rubber composition and a method for producing the same. [Means for solving the problem]

[0015] The present invention relates to a vulcanizing agent composition comprising sulfur and an alkyl ester of a saturated or unsaturated monobasic fatty acid. The present invention also relates to a method for preparing a vulcanizing agent composition, which comprises mixing sulfur and an alkyl ester of a saturated or unsaturated monovalent fatty acid. The present invention also relates to a rubber composition comprising the above vulcanizing agent composition and a rubber component. The present invention also relates to a method for producing a rubber composition, which comprises mixing the above vulcanizing agent composition and a rubber component. The present invention also relates to a vulcanized rubber of the above rubber composition. The present invention also relates to a method for producing a vulcanized rubber, which comprises vulcanizing the above rubber composition. [Effects of the Invention]

[0016] The vulcanizing agent composition of the present invention is sufficiently excellent in antistatic properties and flame resistance, even though it contains sulfur as a vulcanizing agent component. DETAILED DESCRIPTION OF THE INVENTION

[0017] [Vulcanizing agent composition] The vulcanizing agent composition of the present invention comprises sulfur and an alkyl ester of a saturated or unsaturated monobasic fatty acid.

[0018] Any sulfur used in the rubber industry as a vulcanizing agent (or crosslinking agent) can be used. Examples of such sulfur include S8 sulfur and cyclododeca sulfur (S 12In order to further improve antistatic properties and combustion resistance, the sulfur preferably contains one or more selected from the group consisting of S8 sulfur, insoluble sulfur, and mixtures thereof, and more preferably contains insoluble sulfur.

[0019] S8 sulfur refers to a cyclic allotrope of sulfur in which eight sulfur atoms are formed in a single homocyclic ring, and is an inorganic compound (octathiocane) represented by the chemical formula S8. S8 sulfur is solid at room temperature (25°C) and is generally readily soluble in carbon disulfide. In this specification, "easily soluble in carbon disulfide" means that the solubility in carbon disulfide at 25°C is 30% by weight or more. The solubility (wt%) is the ratio of the solute to the total amount (total amount of solvent and solute).

[0020] Cyclododeca sulfur (S 12 ) refers to a cyclic allotrope of sulfur in which 12 sulfur atoms are formed in a single homocyclic ring, and has the chemical formula S 12 It is an inorganic compound (cyclododeca sulfur) expressed as 12 ) is a solid at room temperature (25°C) and is generally insoluble in carbon disulfide.

[0021] Insoluble sulfur is generally a polymeric solid sulfur that is produced when vaporized sulfur heated above its boiling point is rapidly cooled, or when molten sulfur at 159°C or higher is rapidly cooled. It refers to sulfur that is insoluble in carbon disulfide at 25°C. The shape of the insoluble sulfur particles may be spherical or irregular. "Insoluble in carbon disulfide" means that the amount of sulfur that dissolves in carbon disulfide at 25°C is less than 1% by weight.

[0022] The sulfur preferably contains insoluble sulfur. Insoluble sulfur usually has relatively low dispersibility in rubber components. However, in the present invention, even when such insoluble sulfur is used, the dispersibility of the sulfur in the rubber components is improved by using an alkyl ester of a saturated or unsaturated monovalent fatty acid, which will be described later, and the vulcanizing agent composition has sufficiently excellent antistatic properties and flame resistance. By containing insoluble sulfur as sulfur, the vulcanizing agent composition can more effectively suppress blooming, in which sulfur migrates to the surface of the rubber and precipitates in the vulcanized rubber.

[0023] As used herein, antistatic property refers to the property of a vulcanizing agent composition that makes it difficult for the composition to become electrically charged. Vulcanizing agent compositions generally have a powdery form and are prone to static electricity. Therefore, they may become electrically charged due to contact and friction between particles of the vulcanizing agent composition, or due to contact and friction with measuring equipment and kneading equipment during compounding into rubber. On the other hand, the vulcanizing agent composition of the present invention has superior antistatic properties and is difficult to become electrically charged, thereby more fully preventing phenomena such as adhesion to equipment and facilities and reduced fluidity due to static electricity. As a result, the vulcanizing agent composition of the present invention can more fully prevent dust explosions. Flame resistance refers to the property that the vulcanizing agent composition is difficult to ignite even when brought into contact with a flame, and even if it does ignite and begin to burn, the burning does not continue and the flame quickly goes out by itself.

[0024] The average particle size of sulfur is usually 0.1 to 300 μm, preferably 1 to 50 μm, and more preferably 5 to 25 μm. The average particle size refers to the median diameter (D50), which means the particle size at which the integrated value in the particle size distribution measured using a particle size distribution measuring device based on the laser diffraction / scattering method is 50%.

[0025] The average particle size of the vulcanizing agent composition is approximately the same as the average particle size of the sulfur contained in the vulcanizing agent composition, and is usually 0.1 to 300 μm, preferably 1 to 50 μm, and more preferably 5 to 25 μm.

[0026] The alkyl ester of saturated or unsaturated monovalent fatty acid is formed by an ester bond between the carboxyl group of the saturated or unsaturated monovalent fatty acid and an alkyl group. The fatty acid constituting the alkyl ester of saturated or unsaturated monovalent fatty acid may have one or more (e.g., 1 to 4, particularly 1 to 3) unsaturated bonds such as double or triple bonds in one molecule, or may have no unsaturated bonds, or may be a mixture thereof. The vulcanizing agent composition of the present invention, containing the alkyl ester of saturated or unsaturated monovalent fatty acid, has sufficiently excellent antistatic properties and flame resistance. Specifically, the vulcanizing agent composition of the present invention has sufficiently excellent antistatic properties, which further reduces adhesion to equipment, etc., improving workability during rubber mixing. The vulcanizing agent composition of the present invention also has sufficiently excellent flame resistance, which sufficiently shortens the duration of combustion upon ignition and improves safety. If the vulcanizing agent composition uses only naphthenic oil and / or vegetable oil, which are conventionally used as process oils in the rubber industry, instead of the alkyl ester of saturated or unsaturated monovalent fatty acid, the antistatic properties will be reduced. As a result, adhesion to equipment and the like cannot be sufficiently prevented, and / or it becomes necessary to prevent dust explosions. Moreover, in this case, the flame resistance may also be reduced.

[0027] Specifically, the vulcanizing agent composition of the present invention exhibits a flash point (approximately −10 to 200°C) that is lower than or comparable to that of vegetable oils and fats. Therefore, it is expected that the vulcanizing agent composition of the present invention, which contains sulfur and a saturated or unsaturated monocarboxylic acid alkyl ester as a process oil, will have a burning duration upon ignition that is longer than or comparable to that of a vulcanizing agent composition containing vegetable oil and fats as a process oil. However, contrary to expectations, it was found that the vulcanizing agent composition of the present invention has a burning duration that is significantly shorter than that of a vulcanizing agent composition using vegetable oil and fats as a process oil. The mechanism behind this is presumably that the alkyl ester of saturated or unsaturated monocarboxylic acid is more volatile than vegetable oil and fats, which prevents the surface temperature of the vulcanizing agent composition from rising when a flame is brought close to the vulcanizing agent composition, thereby preventing the sulfur from reaching its ignition point, and also prevents oxygen from being supplied from the air to the ignition point.

[0028] The number of carbon atoms in the fatty acid constituting the alkyl ester of saturated or unsaturated monovalent fatty acid is not particularly limited, and is usually 10 to 30, and from the viewpoint of further improving antistatic properties and flame resistance, it is preferably 14 to 26, more preferably 16 to 22, and particularly preferably 16 to 18. The number of carbon atoms in the fatty acid is the number of carbon atoms in the hydrocarbon chain constituting the fatty acid, and includes the carbon atoms constituting the carboxyl group.

[0029] The fatty acid constituting the alkyl ester of saturated or unsaturated monovalent fatty acid may be, for example, one or more selected from the group consisting of decanoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, arachidic acid, eicosadienoic acid, eicosatrienoic acid, arachidonic acid, eicosapentaenoic acid, behenic acid, erucic acid, docosahexaenoic acid, lignoceric acid, and mixtures thereof. Thus, the alkyl ester of a saturated or unsaturated monovalent fatty acid may be one or more selected from the group consisting of alkyl esters of decanoic acid, alkyl esters of lauric acid, alkyl esters of myristic acid, alkyl esters of palmitic acid, alkyl esters of stearate, alkyl esters of oleic acid, alkyl esters of linoleic acid, alkyl esters of linolenic acid, alkyl esters of arachidic acid, alkyl esters of eicosadienoic acid, alkyl esters of eicosatrienoic acid, alkyl esters of arachidonic acid, alkyl esters of eicosapentaenoic acid, alkyl esters of behenic acid, alkyl esters of erucic acid, alkyl esters of docosahexaenoic acid, alkyl esters of lignoceric acid, and mixtures thereof.

[0030] The alkyl constituting the alkyl ester of saturated or unsaturated monovalent fatty acid may be, for example, methyl, ethyl, isopropyl, n-butyl, isobutyl, 2-ethylhexyl, or a mixture thereof. Thus, the alkyl ester of saturated or unsaturated monovalent fatty acid may be one or more selected from the group consisting of methyl ester of saturated or unsaturated monovalent fatty acid, ethyl ester of saturated or unsaturated monovalent fatty acid, isopropyl ester of saturated or unsaturated monovalent fatty acid, n-butyl ester of saturated or unsaturated monovalent fatty acid, isobutyl ester of saturated or unsaturated monovalent fatty acid, 2-ethylhexyl ester of saturated or unsaturated monovalent fatty acid, and mixtures thereof. From the viewpoint of further improving antistatic properties and flame resistance, the alkyl ester of saturated or unsaturated monovalent fatty acid preferably includes one or more selected from the group consisting of methyl esters of saturated or unsaturated monovalent fatty acids, ethyl esters of saturated or unsaturated monovalent fatty acids, isopropyl esters of saturated or unsaturated monovalent fatty acids, n-butyl esters of saturated or unsaturated monovalent fatty acids, isobutyl esters of saturated or unsaturated monovalent fatty acids, and mixtures thereof, and more preferably includes methyl esters of saturated or unsaturated monovalent fatty acids.

[0031] Specific examples of alkyl esters of saturated or unsaturated monovalent fatty acids include decanoic acid methyl ester, decanoic acid ethyl ester, decanoic acid isopropyl ester, decanoic acid n-butyl ester, decanoic acid isobutyl ester, decanoic acid 2-ethylhexyl ester, lauric acid methyl ester, lauric acid ethyl ester, lauric acid isopropyl ester, lauric acid n-butyl ester, lauric acid isobutyl ester, lauric acid 2-ethylhexyl ester, myristate methyl ester, myristate ethyl ester, myristate isopropyl ester esters, myristate n-butyl ester, myristate isobutyl ester, myristate 2-ethylhexyl ester, palmitate methyl ester, palmitate ethyl ester, palmitate isopropyl ester, palmitate n-butyl ester, palmitate isobutyl ester, palmitate 2-ethylhexyl ester, stearate methyl ester, stearate ethyl ester, stearate isopropyl ester, stearate n-butyl ester, stearate isobutyl ester, stearate 2-ethylhexyl ester ester, oleic acid methyl ester, oleic acid ethyl ester, oleic acid isopropyl ester, oleic acid n-butyl ester, oleic acid isobutyl ester, oleic acid 2-ethylhexyl ester, linoleic acid methyl ester, linoleic acid ethyl ester, linoleic acid isopropyl ester, linoleic acid n-butyl ester, linoleic acid isobutyl ester, linoleic acid 2-ethylhexyl ester, linolenic acid methyl ester, linolenic acid ethyl ester, linolenic acid isopropyl ester, linolenic acid n-butyl ester, linolenic acid iso butyl ester, linolenic acid 2-ethylhexyl ester, arachidic acid methyl ester, arachidic acid ethyl ester, arachidic acid isopropyl ester, arachidic acid n-butyl ester, arachidic acid isobutyl ester, arachidic acid 2-ethylhexyl ester, eicosadienoic acid methyl ester, eicosadienoic acid ethyl ester, eicosadienoic acid isopropyl ester, eicosadienoic acid n-butyl ester, eicosadienoic acid isobutyl ester, eicosadienoic acid 2-ethylhexyl ester, eicosatrienoic acid methyl ester,Eicosatrienoic acid ethyl ester, eicosatrienoic acid isopropyl ester, eicosatrienoic acid n-butyl ester, eicosatrienoic acid isobutyl ester, eicosatrienoic acid 2-ethylhexyl ester, arachidonic acid methyl ester, arachidonic acid ethyl ester, arachidonic acid isopropyl ester, arachidonic acid n-butyl ester, arachidonic acid isobutyl ester, arachidonic acid 2-ethylhexyl ester, eicosapentaenoic acid methyl ester, eicosapentaenoic acid ethyl ester, eicosapentaenoic acid isopropyl ester, eicosapentaenoic acid n-butyl ester, eicosapentaenoic acid isobutyl ester, eicosapentaenoic acid 2-ethylhexyl ester, behenic acid methyl ester, behenic acid ethyl ester, behenic acid isopropyl ester, behenic acid n-butyl ester behenic acid isobutyl ester, behenic acid 2-ethylhexyl ester, erucic acid methyl ester, erucic acid ethyl ester, erucic acid isopropyl ester, erucic acid n-butyl ester, erucic acid isobutyl ester, erucic acid 2-ethylhexyl ester, docosahexaenoic acid methyl ester, docosahexaenoic acid ethyl ester, docosahexaenoic acid isopropyl ester, docosahexaenoic acid n-butyl ester, docosahexaenoic acid isobutyl ester, docosahexaenoic acid 2-ethylhexyl ester, lignoceric acid methyl ester, lignoceric acid ethyl ester, lignoceric acid isopropyl ester, lignoceric acid n-butyl ester, lignoceric acid isobutyl ester, lignoceric acid 2-ethylhexyl ester, and mixtures of two or more thereof.

[0032] The alkyl ester of saturated or unsaturated monovalent fatty acid preferably contains an alkyl ester of saturated or unsaturated monovalent fatty acid that is liquid at room temperature (25°C). This is because the inclusion of such an alkyl ester of saturated or unsaturated monovalent fatty acid in the vulcanizing agent composition facilitates uniform mixing of sulfur and the alkyl ester of saturated or unsaturated monovalent fatty acid. Examples of alkyl esters of saturated or unsaturated monovalent fatty acid that are liquid at room temperature include methyl oleate, ethyl oleate, methyl linoleate, ethyl linoleate, methyl linolenate, and ethyl linolenate. Even if the alkyl ester of saturated or unsaturated monovalent fatty acid is liquid at room temperature, the alkyl ester of saturated or unsaturated monovalent fatty acid is adsorbed to the surface of sulfur particles, allowing the vulcanizing agent composition of the present invention to maintain a powder form.

[0033] In the alkyl ester of saturated or unsaturated monovalent fatty acid, the content of the alkyl ester of saturated or unsaturated monovalent fatty acid that is liquid at room temperature is not particularly limited, and may be, for example, 20% by weight or more relative to the total amount of alkyl ester of saturated or unsaturated monovalent fatty acid, and from the viewpoint of further improving antistatic properties and flame resistance, may be preferably 40% by weight or more, more preferably 60% by weight or more. The upper limit of this content is not particularly limited, and this content is usually 100% by weight or less.

[0034] Alkyl esters of saturated or unsaturated monovalent fatty acids can be synthesized by transesterification of monoglycerides, diglycerides, and triglycerides, the main components of fats and oils, with alkyl alcohols. Examples of fats and oils include vegetable and animal fats and oils. Vegetable fats and oils include soybean oil, rapeseed oil, linseed oil, palm oil, palm kernel oil, sunflower oil, rice oil, sesame oil, corn oil, coconut oil, safflower oil, safflower oil, peanut oil, cottonseed oil, mustard oil, pongamia oil, jatropha oil, mahua oil, and rubber oil. Animal fats and oils include beef tallow, lard, whale oil, and fish oil. Among vegetable fats and oils, pongamia oil, jatropha oil, mahua oil, and rubber oil are generally not used for food and are referred to as non-edible oils.

[0035] Alkyl esters of saturated or unsaturated monovalent fatty acids can also be synthesized by esterification of saturated or unsaturated monovalent fatty acids with alkyl alcohols. Examples of saturated or unsaturated monovalent fatty acids include the fatty acids that form the alkyl esters of the saturated or unsaturated monovalent fatty acids described above. Examples of alkyl alcohols include methanol, ethanol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol, and mixtures thereof.

[0036] Biodiesel (BDF) is a fuel synthesized from biologically derived fats and oils, such as vegetable and animal fats and oils. Biodiesel is a mixture of saturated or unsaturated monovalent fatty acids obtained by esterifying vegetable and animal fats and / or their waste cooking oils with an alkyl alcohol (particularly, methyl esterification with methanol). Biodiesel also refers to a mixture of saturated or unsaturated monovalent fatty acids obtained by esterifying fatty acids with an alkyl alcohol (particularly, methyl esterification with methanol) from fatty acids by-produced in the process of producing vegetable oils and fats (e.g., rice bran) from vegetable oils and fats. The alkyl alcohol used to esterify the feedstock or fatty acids may be, for example, methanol, ethanol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylhexyl alcohol, or a mixture thereof. The present invention can contribute to sustainability and carbon neutrality by using biodiesel containing, as its main component, alkyl esters of saturated or unsaturated monovalent fatty acids, which are made from vegetable oils and fats, animal oils and fats, and / or waste cooking oils thereof. Furthermore, the use of biodiesel containing, as its main component, alkyl esters of saturated or unsaturated monovalent fatty acids, which are made from fatty acids by-produced in the process of producing vegetable oils and fats from vegetable oils and fats, can contribute to sustainability and carbon neutrality. Furthermore, using biomethanol (or bioethanol) produced from biologically derived raw materials as the methanol (or ethanol) used in methyl esterification (or ethyl esterification) can further contribute to sustainability and carbon neutrality. From this perspective, the alkyl esters of saturated or unsaturated monovalent fatty acids are preferably derived from biodiesel. The phrase "the alkyl esters of saturated or unsaturated monovalent fatty acids are derived from biodiesel" means that the alkyl esters of saturated or unsaturated monovalent fatty acids include alkyl esters of saturated or unsaturated monovalent fatty acids derived from biodiesel.The alkyl ester of saturated or unsaturated monovalent fatty acid is preferably derived from methyl esterification of vegetable oils, animal oils, and / or their waste cooking oils, more preferably from methyl esterification of vegetable oils and / or their waste cooking oils, and even more preferably from methyl esterification of non-edible oils and / or their waste cooking oils. For example, the alkyl ester of saturated or unsaturated monovalent fatty acid preferably comprises a saturated or unsaturated monovalent fatty acid methyl ester mixture obtained by methyl esterification of vegetable oils, animal oils, and / or their waste cooking oils, more preferably from methyl esterification of vegetable oils and / or their waste cooking oils, and even more preferably from methyl esterification of non-edible oils and / or their waste cooking oils.

[0037] The content of the alkyl ester of saturated or unsaturated monovalent fatty acid in the vulcanizing agent composition is not particularly limited, and is usually 1 to 66 parts by weight per 100 parts by weight of sulfur. From the viewpoint of further improving antistatic properties and flame resistance, it is preferably 2 to 60 parts by weight, more preferably 5 to 50 parts by weight, even more preferably 8 to 40 parts by weight, and particularly preferably 10 to 30 parts by weight. When the vulcanizing agent composition contains one or more alkyl esters of saturated or unsaturated monovalent fatty acid, the total content thereof may be within the above range.

[0038] The present invention does not preclude the vulcanizing agent composition from further containing a process oil conventionally used in the rubber field (hereinafter, sometimes simply referred to as "other process oil"). Examples of such other process oils include mineral oils (paraffinic process oil, naphthenic process oil, aromatic process oil, liquid paraffin, petrolatum, Gilsonite, and petroleum asphalt); vegetable oils and fats (soybean oil, rapeseed oil, linseed oil, palm oil, palm kernel oil, sunflower oil, rice bran oil, sesame oil, corn oil, coconut oil, safflower oil, safflower oil, peanut oil, cottonseed oil, mustard oil, pongamia oil, jatropha oil, and mahua oil); sub(factice); and rubber process oils such as fatty acids and fatty acid derivatives. Fatty acid derivatives refer to fatty acid derivatives other than the alkyl esters of the aforementioned saturated or unsaturated monovalent fatty acids. Examples of such fatty acid derivatives include monoacylglycerol, diacylglycerol, sorbitan fatty acid ester, ethylene glycol fatty acid ester, polyethylene glycol fatty acid ester, propylene glycol fatty acid ester, polyglycerol fatty acid ester, sucrose fatty acid ester, fatty acid amide, fatty acid chloride, aliphatic amine, etc. As the other process oil, one or more selected from the above-mentioned rubber process oils can be used.

[0039] The content ratio of other process oils in the vulcanizing agent composition is not particularly limited, and is usually 66 parts by weight or less (particularly from 0 to 66 parts by weight) per 100 parts by weight of sulfur. From the viewpoint of further improving antistatic properties and flame resistance, it is preferably 50 parts by weight or less (particularly from 0 to 50 parts by weight), more preferably 20 parts by weight or less (particularly from 0 to 20 parts by weight), even more preferably 10 parts by weight or less (particularly from 0 to 10 parts by weight), sufficiently preferably 1 part by weight or less (particularly 0 to 1 part by weight), and even sufficiently preferably 0 part by weight.

[0040] The vulcanizing agent composition of the present invention may further contain, as necessary, one or more additives selected from vulcanization accelerators, stabilizers, antioxidants, dispersing aids, and vulcanization acceleration aids.

[0041] Examples of vulcanization accelerators include aldehyde-ammonia compounds, aldehyde-amine compounds, guanidine compounds, thiourea compounds, thiazole compounds, sulfenamide compounds, thiuram compounds, thidiocarbamate compounds, and xanthogenate compounds. The content of the vulcanization accelerator is not particularly limited, but is usually 20 parts by weight or less (especially 0 to 20 parts by weight) per 100 parts by weight of sulfur. From the viewpoint of further improving antistatic properties and flame resistance, it is preferably 10 parts by weight or less (especially 0 to 10 parts by weight), more preferably 5 parts by weight or less (especially 0 to 5 parts by weight), and even more preferably 1 part by weight or less (especially 0 to 1 part by weight). When the vulcanization agent composition contains one or more vulcanization accelerators, the total content of the accelerators should be within the above range.

[0042] Examples of stabilizers include α-methylstyrene (αMS), bromine, iodine, potassium iodide, iron(III) chloride, nitric acid, ammonium persulfate, sodium ethylxanthate, vinyltoluene, terpineol, and zinc sulfate. The stabilizer content is not particularly limited and is usually 20 parts by weight or less (particularly 0 to 20 parts by weight) per 100 parts by weight of sulfur. From the viewpoint of further improving antistatic properties and flame resistance, it is preferably 10 parts by weight or less (particularly 0 to 10 parts by weight), more preferably 5 parts by weight or less (particularly 0 to 5 parts by weight), and even more preferably 1 part by weight or less (particularly 0 to 1 part by weight). When the vulcanizing agent composition contains one or more stabilizers, the total content of those stabilizers should be within the above range.

[0043] Examples of antioxidants include amine-based antioxidants, phenol-based antioxidants, sulfur-based antioxidants, and phosphoric acid-based antioxidants. The content of the antioxidant is not particularly limited and is usually 20 parts by weight or less (particularly 0 to 20 parts by weight) per 100 parts by weight of sulfur. From the viewpoint of further improving antistatic properties and flame resistance, it is preferably 10 parts by weight or less (particularly 0 to 10 parts by weight), more preferably 5 parts by weight or less (particularly 0 to 5 parts by weight), even more preferably 1 part by weight or less (particularly 0 to 1 part by weight), and particularly preferably 0.5 parts by weight or less (particularly 0 to 0.5 parts by weight). When the vulcanizing agent composition contains one or more antioxidants, the total content thereof may be within the above range.

[0044] Examples of dispersing aids include silica. The content of the dispersing aid is not particularly limited and is usually 20 parts by weight or less (particularly 0 to 20 parts by weight) per 100 parts by weight of sulfur. From the viewpoint of further improving antistatic properties and flame resistance, it is preferably 10 parts by weight or less (particularly 0 to 10 parts by weight), more preferably 5 parts by weight or less (particularly 0 to 5 parts by weight), and even more preferably 1 part by weight or less (particularly 0 to 1 part by weight). When the vulcanizing agent composition contains one or more dispersing aids, the total content thereof may be within the above range.

[0045] Examples of vulcanization accelerators include metal hydroxides such as magnesium hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, and copper hydroxide; metal oxides such as magnesium oxide, calcium oxide, zinc oxide, and copper oxide; and metal carbonates such as magnesium carbonate, calcium carbonate, sodium carbonate, lithium carbonate, and potassium carbonate. The content of the vulcanization accelerator is not particularly limited, but is usually 20 parts by weight or less (particularly 0 to 20 parts by weight) per 100 parts by weight of sulfur. From the viewpoint of further improving antistatic properties and flame resistance, it is preferably 10 parts by weight or less (particularly 0 to 10 parts by weight), more preferably 5 parts by weight or less (particularly 0 to 5 parts by weight), even more preferably 1 part by weight or less (particularly 0 to 1 part by weight), and most preferably 0 part by weight. When the vulcanizing agent composition contains one or more vulcanization accelerators, the total content of these may be within the above range.

[0046] The vulcanizing agent composition of the present invention is useful as a vulcanizing agent for various rubber components, and can be suitably used, for example, as a vulcanizing agent for producing rubber materials that require high hardness (particularly, rubber for tires, seismic isolation rubber, vibration damping rubber, conveyor belts, etc.).

[0047] [Method of producing vulcanizing agent composition] The vulcanizing agent composition can be produced by mixing sulfur, an alkyl ester of saturated or unsaturated monovalent fatty acid, and optional additives. The mixing method is not particularly limited, and may involve mixing using a known mixing device such as a planetary mixer, or by manually kneading the components. For example, sulfur, an alkyl ester of saturated or unsaturated monovalent fatty acid, and additives may be placed in a polyethylene bag to achieve a predetermined content ratio, sealed, and then manually mixed. The mixing time required to obtain the vulcanizing agent composition is not particularly limited as long as uniform mixing is achieved, and may be, for example, 1 minute to 1 hour, particularly 5 to 30 minutes.

[0048] From the viewpoint of safety, the method for producing the vulcanizing agent composition is preferably carried out in an atmosphere of an inert gas such as nitrogen or argon.

[0049] [Rubber composition and method for producing the same] The present invention also provides a rubber composition. The rubber composition of the present invention comprises the vulcanizer composition of the present invention and a rubber component, and may further comprise compounding agents such as reinforcing agents, antioxidants, softeners, vulcanization accelerators, vulcanization accelerator aids, vulcanization retarders, colorants, foaming agents, dispersants, lubricants, and adhesion promoters, as necessary. The rubber composition of the present invention refers to a rubber composition before vulcanization. Therefore, a kneaded product obtained by kneading a vulcanizer composition and a rubber component at a temperature below the vulcanization temperature is in an unvulcanized state and is therefore classified as a rubber composition. For example, a masterbatch is included in the concept of "rubber composition." A masterbatch is, for example, a material in which a specified compounding agent is pre-mixed into a rubber component in a content greater than the content of the specified compounding agent in a specified product.

[0050] The rubber component is not particularly limited, and examples thereof include natural rubber (NR), butadiene rubber (BR), isoprene rubber (IR), styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPM, EPDM), butyl rubber (IIR), halogenated butyl rubber (X-IIR), chloroprene rubber (CR), silicone rubber (Q), fluororubber (FKM), polysulfide rubber (T), chlorinated polyethylene (CPE), polyurethane (U), Hypalon, ethylene-vinyl acetate-acrylate rubber, epichlorohydrin rubber, acrylic rubber, etc. One or a mixture of two or more of these may be used.

[0051] The amounts of the rubber component and the vulcanizing agent composition of the present invention in the rubber composition are not particularly limited. The content of the vulcanizing agent composition of the present invention is usually 0.1 to 1000 parts by weight, preferably 0.5 to 500 parts by weight, more preferably 1 to 400 parts by weight, and even more preferably 1 to 20 parts by weight, per 100 parts by weight of the rubber component.

[0052] Examples of reinforcing agents include talc, clay, carbon black, white carbon, graphite, calcium carbonate, magnesium carbonate, calcium silicate, etc. Reinforcing agents may also be referred to as fillers. The content of the reinforcing agent is not particularly limited and is usually 20 to 150 parts by weight per 100 parts by weight of the rubber component, and from the viewpoints of hardness and low heat buildup of the rubber composition, it is preferably 30 to 130 parts by weight, and more preferably 35 to 110 parts by weight.

[0053] Examples of antioxidants include amine-based, quinoline-based, quinone-based, phenol-based, imidazole-based, sulfur-based, and phosphorus-based compounds, as well as metal carbamates, etc. The content of the antioxidant is not particularly limited and is usually 0.1 to 11 parts by weight per 100 parts by weight of the rubber component, and from the viewpoints of crack resistance and processability, is preferably 0.3 to 8 parts by weight, and more preferably 0.5 to 6 parts by weight.

[0054] Examples of softeners include mineral oil-based compounds, vegetable oil-based compounds, synthetic resin-based compounds, dioctyl phthalate, and dioctyl sebacate. Softeners can also be called plasticizers. The content of the softener is not particularly limited, and is usually 0.5 to 60 parts by weight per 100 parts by weight of the rubber component. From the viewpoints of workability and flexibility of the rubber composition, it is preferably 1 to 50 parts by weight, and more preferably 2 to 40 parts by weight.

[0055] Examples of vulcanization accelerators include guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, dithiocarbamate-based, xanthate-based, etc. The content ratio of the vulcanization accelerator is not particularly limited, and is usually 0.1 to 7 parts by weight per 100 parts by weight of the rubber component, and from the viewpoints of low heat buildup and crack resistance, it is preferably 0.3 to 5 parts by weight, and more preferably 0.5 to 3 parts by weight.

[0056] Examples of the vulcanization accelerator aid include metal hydroxides such as magnesium hydroxide, calcium hydroxide, sodium hydroxide, lithium hydroxide, potassium hydroxide, and copper hydroxide; metal oxides such as magnesium oxide, calcium oxide, zinc oxide, and copper oxide; and metal carbonates such as magnesium carbonate, calcium carbonate, sodium carbonate, lithium carbonate, and potassium carbonate. The content of the vulcanization accelerator aid is not particularly limited and is usually 1 to 18 parts by weight per 100 parts by weight of the rubber component, and from the viewpoint of vulcanization acceleration, it is preferably 3 to 15 parts by weight, and more preferably 5 to 12 parts by weight.

[0057] Examples of vulcanization retarders include phthalic anhydride, benzoic acid, salicylic acid, N-nitrosodiphenylamine, N-cyclohexylthiophthalimide, N-(trichloromethylthio)benzenesulfonamide, etc. The content of the vulcanization retarder is not particularly limited, and is usually 0.01 to 3 parts by weight per 100 parts by weight of the rubber component, and from the viewpoints of workability and prevention of rubber burning, it is preferably 0.05 to 2.5 parts by weight, more preferably 0.1 to 2 parts by weight.

[0058] The colorant may be one or a combination of two or more inorganic or organic pigments and dyes, such as iron oxide, aniline black, bone black, titanium white, phthalocyanines, azo dyes, anthraquinone dyes, quinacridone dyes, isoindolinone dyes, dioxazine dyes, perylene dyes, quinophthalone dyes, perinone dyes, xanthene dyes, cobalt blue, cobalt green, cobalt yellow, cadmium sulfide, cadmium selenide, ultramarine, red iron oxide, chromium oxide, lead chromate, Milori blue, titanium yellow, nickel yellow, bismuth yellow, mica titanium, oil black, malacaine green, rhodamine B, and benzimidazolone dyes. The content of the colorant is not particularly limited and is usually 0.01 to 50 parts by weight per 100 parts by weight of the rubber component. From the viewpoint of improving appearance, it is preferably 0.01 to 30 parts by weight, and more preferably 0.01 to 10 parts by weight.

[0059] Examples of foaming agents include azodicarbonamide (ADCA), dinitrosopentamethylenetetramine (DPT), dinitrosopentastyrenetetramine, benzenesulfonylhydrazide derivatives, p,p'-oxybisbenzenesulfonylhydrazide (OBSH), ammonium bicarbonate that generates carbon dioxide, sodium bicarbonate, ammonium carbonate, nitrososulfonyl azo compounds that generate nitrogen, N,N'-dimethyl-N,N'-dinitrosophthalamide, toluenesulfonylhydrazide, p-toluenesulfonylsemicarbazide, p,p'-oxybisbenzenesulfonylsemicarbazide, etc. The content of the foaming agent is not particularly limited and is usually 1 to 20 parts by weight per 100 parts by weight of the rubber component, and from the viewpoint of anti-slip properties, it is preferably 3 to 18 parts by weight, more preferably 5 to 15 parts by weight.

[0060] Examples of dispersants include silane coupling agents having a sulfide group, a mercapto group, a thioester group, a vinyl group, or an amino group; glycidoxy-based, nitro-based, or chloro-based silane coupling agents; polyalkylene glycols; amine-based compounds; silane-based compounds; epoxy-based compounds; and guanidine-based compounds. The content of the dispersant is not particularly limited, and is usually 0.1 to 30 parts by weight per 100 parts by weight of the reinforcing agent component, and from the viewpoints of low heat buildup and abrasion resistance, is preferably 0.5 to 25 parts by weight, and more preferably 1 to 20 parts by weight.

[0061] Examples of lubricants include higher fatty acid amides such as oleic acid amide, stearic acid amide, behenic acid amide, and ethylene bisstearoid, saturated and unsaturated fatty acids such as stearic acid, palmitic acid, myristic acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, capric acid, pelargonic acid, caprylic acid, enanthic acid, caproic acid, oleic acid, vaccenic acid, linoleic acid, linolenic acid, and nervonic acid, silicone oil, and higher fatty acid esters. The content of the lubricant is not particularly limited, and is usually 0.5 to 15 parts by weight per 100 parts by weight of the rubber component, and from the viewpoint of improving processability, it is preferably 1 to 13 parts by weight, and more preferably 2 to 10 parts by weight.

[0062] Examples of adhesion promoters include organic cobalt salts such as cobalt naphthenate, cobalt stearate, cobalt neodecanoate, cobalt rosinate, cobalt versatate, cobalt tallate, cobalt oleate, cobalt linoleate, cobalt linolenate, and cobalt palmitate, as well as bismuth organic salts, aluminum organic salts, zinc organic salts, molybdenum organic salts, and iron organic salts. The content of the adhesion promoter is not particularly limited and is usually 0.1 to 25 parts by weight per 100 parts by weight of the rubber component, and from the viewpoint of adhesion between the vulcanized rubber and metal, is preferably 0.3 to 20 parts by weight, and more preferably 0.5 to 15 parts by weight.

[0063] When the rubber composition of the present invention is produced as a rubber composition for a tire, it is preferable to use a sulfenamide-based compound or the like as a vulcanization accelerator, zinc oxide or the like as a vulcanization accelerator aid, stearic acid or the like as a lubricant, carbon black or the like as a reinforcing agent, an amine-based compound or the like as an antiaging agent, and mineral oil or the like as a softener.

[0064] The rubber composition of the present invention may be produced by mixing the vulcanizing agent composition, the rubber component, and optional compounding ingredients, or by kneading the mixture at a temperature below the vulcanization temperature. The mixing method for obtaining the rubber composition is not particularly limited, and a known mixing device such as a planetary mixer may be used. The mixing time for obtaining the rubber composition is not particularly limited as long as uniform mixing is achieved, and may be, for example, 1 minute to 1 hour, particularly 5 to 30 minutes. The kneading method for obtaining the rubber composition is not particularly limited, and for example, a kneading machine such as a kneader or Banbury mixer; an open roll, etc. may be used. The kneading temperature for obtaining the rubber composition is a temperature below the vulcanization temperature and is not particularly limited, and may be, for example, 130°C or lower (particularly 50 to 130°C), preferably 70 to 110°C, and more preferably 80 to 100°C. The kneading time for obtaining the rubber composition is not particularly limited, and may be, for example, 10 seconds to 20 minutes, and preferably 1 to 10 minutes.

[0065] [Vulcanized rubber and its manufacturing method] The present invention also provides a vulcanized rubber. The vulcanized rubber of the present invention is a vulcanized rubber of the rubber composition of the present invention described above, and more specifically, is a vulcanized rubber obtained by vulcanizing the rubber composition of the present invention described above. More specifically, the vulcanized rubber can be obtained by vulcanizing the rubber composition of the present invention at a suitable vulcanization temperature depending on the type and blending ratio of each component. Vulcanization can be carried out, for example, at 150 to 170°C for about 1 to 30 minutes.

[0066] The vulcanized rubber of the present invention has good mechanical properties (tensile strength, tensile elongation, etc.) both before and after the aging test. The aging test is a test that accelerates the aging of the vulcanized rubber under severe conditions, for example, a test in which the vulcanized rubber is left at 70°C for 4 days.

[0067] The present invention includes the following preferred embodiments. <1> A vulcanizing agent composition comprising sulfur and an alkyl ester of a saturated or unsaturated monovalent fatty acid. <2> The alkyl ester of saturated or unsaturated mono-fatty acid is at least one selected from the group consisting of methyl ester of saturated or unsaturated mono-fatty acid, ethyl ester of saturated or unsaturated mono-fatty acid, isopropyl ester of saturated or unsaturated mono-fatty acid, n-butyl ester of saturated or unsaturated mono-fatty acid, isobutyl ester of saturated or unsaturated mono-fatty acid, 2-ethylhexyl ester of saturated or unsaturated mono-fatty acid, and mixtures thereof. <1> The vulcanizing agent composition according to claim 1. <3> The alkyl ester of a saturated or unsaturated monovalent fatty acid includes an alkyl ester of a saturated or unsaturated monovalent fatty acid that is in a liquid state at room temperature. <1> or <2> The vulcanizing agent composition according to claim 1. <4> The fatty acid constituting the alkyl ester of the saturated or unsaturated monovalent fatty acid is one or more selected from the group consisting of saturated or unsaturated monovalent fatty acids having 14 to 26 carbon atoms. <1> ~ <3> The vulcanizing agent composition according to any one of the preceding claims. <5> The alkyl ester of a saturated or unsaturated monovalent fatty acid is at least one selected from the group consisting of palmitic acid alkyl esters, stearic acid alkyl esters, oleic acid alkyl esters, linoleic acid alkyl esters, linolenic acid alkyl esters, behenic acid alkyl esters, and mixtures thereof. <1> ~ <4> The vulcanizing agent composition according to any one of the preceding claims. <6> The alkyl ester of a saturated or unsaturated monovalent fatty acid is derived from biodiesel. <1> ~ <5> The vulcanizing agent composition according to any one of the preceding claims. <7> The alkyl ester of the saturated or unsaturated monovalent fatty acid is derived from a vegetable oil, an animal oil, and / or a waste cooking oil thereof that has been methyl-esterified. <1> ~ <6> The vulcanizing agent composition according to any one of the preceding claims. <8> The sulfur is S8 sulfur, cyclododeca sulfur (S 12 ), insoluble sulfur, and mixtures thereof; <1> ~ <7> The vulcanizing agent composition according to any one of the preceding claims. <9> The alkyl ester of the saturated or unsaturated monovalent fatty acid is contained in an amount of 1 to 66 parts by weight relative to 100 parts by weight of the sulfur. <1> ~ <8> The vulcanizing agent composition according to any one of the preceding claims. <10> Further, the composition contains one or more additives selected from a vulcanization accelerator, a stabilizer, an antioxidant, a dispersing aid, and a vulcanization acceleration aid. <1> ~ <9> The vulcanizing agent composition according to any one of the preceding claims. <11> A method for producing a vulcanizing agent composition, comprising mixing sulfur and an alkyl ester of a saturated or unsaturated monovalent fatty acid. <12> <11> A vulcanizing agent composition produced by the production method described in . <13> <1> ~ <10> and <12> 10. A rubber composition comprising the vulcanizing agent composition according to claim 1, and a rubber component. <14> The content ratio of the vulcanizing agent composition is 0.1 to 1000 parts by weight based on 100 parts by weight of the rubber component. <13> The rubber composition according to claim 1. <15> <1> ~ <10> and <12> 10. A method for producing a rubber composition, comprising mixing the vulcanizing agent composition according to any one of claims 1 to 9 and a rubber component. <16> <13> or <14> A vulcanized rubber of the rubber composition described in . <17> The vulcanized rubber is a tire rubber. <16> The vulcanized rubber according to claim 1. <18> <13> or <14> 10. A method for producing vulcanized rubber, comprising vulcanizing the rubber composition according to claim 9. [Example]

[0068] [raw materials] <Sulfur> Insoluble sulfur: Shikoku Chemicals Corporation, product name "Mu-Clon" (average particle size 20 μm) S8: Fujifilm Wako Pure Chemical Industries, Ltd., product name: "Sulfur, powder"

[0069] ·S 12 : Cyclododeca sulfur (S 12 ) was synthesized.

[0070] <Process oil> (naphthenic oil) Naphthenic oil A: Idemitsu Kosan Co., Ltd., product name "Diana Process Oil" Naphthenic oil B: Manufactured by Japan Sun Oil Co., Ltd., product name "SUNTHENE"

[0071] (vegetable oil) Soybean oil: Nisshin Oillio Co., Ltd., product name: "Soybean White Oil" Rapeseed oil: Nisshin Oillio Co., Ltd., product name: "Rapeseed White Oil" Linseed oil: Nisshin Oillio Co., Ltd., product name: "N / B Linseed Oil" Palm oil: Nisshin Oillio Co., Ltd., product name "Refined Palm Kernel Oil"

[0072] (Alkyl esters of saturated or unsaturated monovalent fatty acids) Methyl palmitate: Tokyo Chemical Industry Co., Ltd., product name "Methyl palmitate" reagent (solid at room temperature (25°C)) Methyl stearate: Tokyo Chemical Industry Co., Ltd., product name "Methyl stearate" reagent (solid at room temperature (25°C)) Methyl oleate: Tokyo Chemical Industry Co., Ltd., product name "Methyl oleate" reagent (liquid at room temperature (25°C)) Methyl linoleate: Tokyo Chemical Industry Co., Ltd., product name "Methyl linoleate" reagent (liquid at room temperature (25°C)) Methyl linolenate: Tokyo Chemical Industry Co., Ltd., product name "Methyl linolenate" reagent (liquid at room temperature (25°C)) Methyl behenate: Tokyo Chemical Industry Co., Ltd., product name "Methyl behenate" reagent (solid at room temperature (25°C)) Ethyl oleate: Tokyo Chemical Industry Co., Ltd., product name "Ethyl oleate" reagent (liquid at room temperature (25°C)) Ethyl linoleate: Tokyo Chemical Industry Co., Ltd., product name "Ethyl linoleate" reagent (liquid at room temperature (25°C))

[0073] Biodiesel A: Manufactured by Daikiaxis, product name "D·OiLN (without antioxidants)" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from waste cooking oil. Biodiesel A was made using the above product, but as mentioned above, the saturated or unsaturated monovalent fatty acids were derived from waste cooking oil during the production of the product, so Biodiesel A is also derived from waste cooking oil.

[0074] Biodiesel B: Manufactured by Daikiaxis, product name "D·OiLN" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; the alkyl esters of saturated or unsaturated monovalent fatty acids are the same as those in Biodiesel A. Biodiesel B also contains antioxidants. The saturated or unsaturated monovalent fatty acids are derived from waste cooking oil. Biodiesel B uses the above product, but as mentioned above, the saturated or unsaturated monovalent fatty acids are derived from waste cooking oil during the production of the product, so Biodiesel B is also derived from waste cooking oil.

[0075] Biodiesel C: Manufactured by Toshin Yushi Co., Ltd., product name "TOSOLV-ME" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from soybean oil. Biodiesel C is a mixture of alkyl esters of saturated or unsaturated monovalent fatty acids obtained by esterifying soybean oil with methanol.

[0076] Biodiesel D: Manufactured by Toshin Yushi Co., Ltd., product name "TOSOLV-RBP" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to n-butyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from rice bran oil. Biodiesel D is a mixture of alkyl esters of saturated or unsaturated monovalent fatty acids obtained by esterifying fatty acids with n-butyl alcohol, which are by-products in the process of producing rice bran oil from rice bran.

[0077] Biodiesel E: Manufactured by Toshin Yushi Co., Ltd., product name "TOSOLV-RO" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to 2-ethylhexyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from rice bran oil. Biodiesel E is a mixture of alkyl esters of saturated or unsaturated monovalent fatty acids obtained by esterifying fatty acids with 2-ethylhexyl alcohol, which are by-products in the process of producing rice bran oil from rice bran.

[0078] Biodiesel F: Manufactured by Miyoshi Oil & Fats, product name "Fine Ester R-1000" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from rice bran oil. Biodiesel F is a mixture of alkyl esters of saturated or unsaturated monovalent fatty acids obtained by esterifying fatty acids with methanol, which are by-products in the process of producing rice bran oil from rice bran.

[0079] Biodiesel G: Manufactured by Tsuno Oleochemicals, product name "TFE-ME" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from waste cooking oil. Biodiesel G uses the above product, but as mentioned above, the saturated or unsaturated monovalent fatty acids are derived from waste cooking oil during the production of the product, so Biodiesel G is also derived from waste cooking oil.

[0080] Biodiesel H: Manufactured by Tsuno Oleochemicals, product name "TFE-MED" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from waste cooking oil. Biodiesel H uses the above product, but as mentioned above, the saturated or unsaturated monovalent fatty acids are derived from waste cooking oil during the production of this product, so Biodiesel H is also derived from waste cooking oil.

[0081] Biodiesel I: TOENOL #3100 (liquid at room temperature (25°C)), manufactured by Toei Chemical Co., Ltd., contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from rice bran oil. Biodiesel I is a mixture of alkyl esters of saturated or unsaturated monovalent fatty acids obtained by esterifying fatty acids with methanol, which are by-products in the process of producing rice bran oil from rice bran.

[0082] Biodiesel J: Manufactured by Toei Chemical Co., Ltd., product name "TOENOL #3120" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from waste cooking oil. Biodiesel J uses the above product, but as mentioned above, the saturated or unsaturated monovalent fatty acids are derived from waste cooking oil during the production of the product, so Biodiesel J is also derived from waste cooking oil.

[0083] Biodiesel K: Manufactured by Chengde Oil & Fat Co., Ltd., product name: "USED COOKING OIL METHYL ESTER (UCOME)" (liquid at room temperature (25°C)), contains 96.5% or more alkyl esters of saturated or unsaturated monovalent fatty acids; here, alkyl esters of saturated or unsaturated monovalent fatty acids refer to methyl esters of saturated or unsaturated monovalent fatty acids with 16 to 18 carbon atoms. The saturated or unsaturated monovalent fatty acids are derived from waste cooking oil. Biodiesel K uses the above product, but as mentioned above, the saturated or unsaturated monovalent fatty acids are derived from waste cooking oil during the production of the product, so Biodiesel K is also derived from waste cooking oil.

[0084] (adjusting oil) The above alkyl esters of saturated or unsaturated monovalent fatty acids were mixed in the following weight ratios to prepare the adjusted oil. Adjusted Oil A: Methyl palmitate / Methyl stearate / Methyl oleate / Methyl linoleate / Methyl linolenate = 11.9 / 5.6 / 24.7 / 49.5 / 8.3 Adjusting oil B: Methyl palmitate / Methyl stearate / Methyl oleate / Methyl linoleate / Methyl linolenate = 44.4 / 5.1 / 39.4 / 10.1 / 1.0 Adjusting oil C: methyl linoleate / methyl behenate = 95 / 5

[0085] Adjusted oils A and B were prepared by mixing reagents to form alkyl ester compositions of saturated or unsaturated monovalent fatty acids contained in soybean oil and palm oil when they are methyl esterified, based on the fatty acid compositions contained in common soybean oil and palm oil, respectively. Methyl palmitate and methyl stearate are solids at room temperature (25°C), but adjusted oils A and B are liquids at room temperature (25°C). Adjusted Oil C is a mixture of methyl behenate, which is solid at room temperature (25°C), and methyl linoleate, which is liquid at room temperature (25°C). Adjusted Oil C is liquid at room temperature (25°C).

[0086] <Other ingredients> α-Methylstyrene (hereinafter referred to as "αMS"): Manufactured by Mitsui Chemicals, Inc., product name "α-Methylstyrene"

[0087] [Preparation of Vulcanizing Agent Composition] Examples 1 to 23 and Comparative Examples 1 to 11 In each Example / Comparative Example, sulfur, process oil, and αMS were mixed in the mixing ratios shown in Table 1 in a polyethylene bag, which was then sealed. The bag was then mixed by hand for 10 minutes to prepare a vulcanizing agent composition.

[0088] [Static property evaluation test (antistatic property)] The vulcanizing agent composition was subjected to an antistatic property evaluation test to evaluate its antistatic property. Approximately 1 g of the vulcanizing agent composition was weighed and placed in a stainless steel container, the lid of the stainless steel container was closed, and the stainless steel container was shaken by hand for 60 seconds. After shaking, the vulcanizing agent composition was placed in the cup of a charge measurement Faraday cage (manufactured by Nano Seeds, product name "VT-Q100"), and the charge amount (-nC) of the vulcanizing agent composition was measured. The chargeability per unit weight of the vulcanizing agent composition was calculated using the following formula. The smaller the chargeability value, the lower the chargeability of the vulcanizing agent composition and the better the antistatic properties. The term "chargeability" is used to refer to the absolute value of the charge amount per unit weight of the vulcanizing agent composition. Chargeability (-nC / g) = Charge amount (-nC) ÷ Amount of vulcanizing agent composition added (g) The results of the antistatic property evaluation test are shown in Table 1. The vulcanizing agent compositions of Examples 1 to 23 had smaller antistatic properties than the vulcanizing agent compositions of Comparative Examples 1 to 11, and were sufficiently superior in antistatic properties. The antistatic properties were evaluated based on the following criteria: ◎: Charging property ≦10(-nC / g) (excellent); ○: 10 (-nC / g) < chargeability ≦ 15 (-nC / g) (good); △: 15 (-nC / g) < chargeability ≦ 25 (-nC / g) (no practical problem); ×: 25 (-nC / g)<chargeability (problems in practical use).

[0089] [Ignition test (combustibility)] An ignition test was carried out on the vulcanizing agent compositions of each Example / Comparative Example to evaluate their combustion resistance (continuity of combustion). The flame resistance of the vulcanizing agent composition was evaluated by the "small gas flame ignition test" for Class 2 hazardous materials as defined in the Fire Service Act. The vulcanizing agent composition was molded into a hemispherical shape approximately 30 mm wide x 15 mm high. The molded vulcanizing agent composition was placed on an inorganic heat insulating board, and a simple ignition device (manufactured by Tokai Co., Ltd., product name "CR Chuckaman") was used to apply a flame to the vulcanizing agent composition at an angle of approximately 30° to the horizontal for 10 seconds. The duration of burning of the vulcanizing agent composition after the flame was removed was measured with a stopwatch. This procedure was repeated 10 times, and the longest duration of burning among the 10 times was recorded as the duration of burning of the vulcanizing agent composition. If the duration of burning was less than 10 seconds, it was determined that burning did not continue, and the ignition test (flammability) was evaluated as "Excellent." If the duration of burning was 10 seconds or more, it was determined that burning continued, and the ignition test (flammability) was evaluated as "Poor." The results of the ignition test are shown in Table 1. The vulcanizing agent compositions of Examples 1 to 23 had a shorter combustion duration than the vulcanizing agent compositions of Comparative Examples 3 to 6 and 8, and had a combustion duration equivalent to that of the vulcanizing agent compositions of Comparative Examples 1 to 2, 7, 9 and 11.

[0090] [Method for preparing rubber composition] The masterbatch used was a mixture of natural rubber, carbon black, zinc oxide, naphthenic oil, and stearic acid in the weight ratio of 100:45:5:5:3 in the order listed. 158 parts by weight of the masterbatch (containing 100 parts by weight of natural rubber) was blended with 4.2 parts by weight of each of the vulcanizing agent compositions of Examples 9 to 10 and Comparative Examples 1 to 2 and 1 part by weight of Nt-butyl-2-benzothiazole sulfenamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the mixture was kneaded at a surface temperature of 85°C using a two-roll mixer (manufactured by Mize Testing Instruments Co., Ltd., product name "No. 536 Mixing Roll Machine") to prepare a rubber composition.

[0091] [Moony Coach Time] Using rubber compositions prepared using each of the vulcanizing agent compositions of Examples 9-10 and Comparative Examples 1-2, Mooney scorch time (T5 (min)) was measured using a Mooney viscometer (AM-3, manufactured by Toyo Seiki Seisaku-sho, Ltd.) according to the method specified in JIS K 6300-1. Mooney scorch time indicates the time it takes for unvulcanized rubber to scorch (note: also known as initial vulcanization, early vulcanization, or burning). The smaller this value, the more likely it is that the rubber composition (compounded rubber) will vulcanize during storage or during processing operations prior to the vulcanization step, such as kneading, calendaring, extrusion, etc., resulting in a decrease in plasticity and an increase in elasticity, resulting in a decrease in processability (moldability). Therefore, a larger Mooney scorch time value is preferable. The measurement results of the Mooney scorch time are shown in Table 2. The rubber compositions prepared using the vulcanizing agent compositions of Examples 9 and 10 exhibited Mooney scorch times equivalent to those of the rubber compositions prepared using the vulcanizing agent compositions of Comparative Examples 1 and 2, and exhibited equivalent rubber physical properties.

[0092] [Initial and aged tensile strength and elongation] The rubber compositions prepared using each of the vulcanizing agent compositions of Examples 9-10 and Comparative Examples 1-2 were vulcanized using a small testing press (MP-SNL, manufactured by Toyo Seiki Co., Ltd.) under conditions of 160°C / 15 MPa / 10 minutes. The tensile strength (MPa) and tensile elongation (%) of the vulcanized rubber compositions were measured using an autograph (AGS-X 5kN, manufactured by Shimadzu Corporation) according to the method specified in JIS K 6251. Each rubber composition was left at 23°C for 24 hours (initial) and then treated at 70°C for 4 days (aged) using a gear aging tester (manufactured by Mize Testing Instruments, product name "No. 501-I Gear Aging Tester"). Regarding tensile strength, the larger the numerical value, the better the product is judged to be. On the other hand, regarding tensile elongation, although the judgment differs depending on the application, regarding tensile elongation of rubber for tires in which the vulcanizing agent composition is used as a vulcanizing agent, the larger the numerical value, the better the product is judged to be. The measurement results of the tensile strength and tensile elongation at the initial stage and after aging are shown in Table 2. The rubber compositions prepared using the vulcanizing agent compositions of Examples 9 and 10 exhibited the same tensile strength and tensile elongation as the rubber compositions prepared using the vulcanizing agent compositions of Comparative Examples 1 and 2, regardless of whether they were at the initial stage or after aging, and thus exhibited the same rubber physical properties.

[0093] [Table 1]

[0094] [Table 2] [Industrial Applicability]

[0095] The vulcanizing agent composition and its production method, as well as the rubber composition and its production method of the present invention are useful in the field of vulcanized rubber production, and are particularly useful in the field of production of rubber materials that require high hardness, such as rubber for tires, seismic isolation rubber, vibration damping rubber, conveyor belts, etc.

Claims

1. A vulcanizing agent composition comprising sulfur and an alkyl ester of a saturated or unsaturated monovalent fatty acid.

2. 2. The vulcanizing agent composition according to claim 1, wherein the alkyl ester of a saturated or unsaturated monovalent fatty acid is at least one selected from the group consisting of methyl esters of saturated or unsaturated monovalent fatty acids, ethyl esters of saturated or unsaturated monovalent fatty acids, isopropyl esters of saturated or unsaturated monovalent fatty acids, n-butyl esters of saturated or unsaturated monovalent fatty acids, isobutyl esters of saturated or unsaturated monovalent fatty acids, 2-ethylhexyl esters of saturated or unsaturated monovalent fatty acids, and mixtures thereof.

3. 2. The vulcanizing agent composition according to claim 1, wherein the alkyl ester of a saturated or unsaturated monovalent fatty acid comprises an alkyl ester of a saturated or unsaturated monovalent fatty acid that is in a liquid state at room temperature.

4. The vulcanizing agent composition according to claim 1, wherein the fatty acid constituting the alkyl ester of the saturated or unsaturated monovalent fatty acid is one or more selected from the group consisting of saturated or unsaturated monovalent fatty acids having 14 to 26 carbon atoms.

5. 2. The vulcanizing agent composition of claim 1, wherein the alkyl ester of a saturated or unsaturated monovalent fatty acid is one or more selected from the group consisting of alkyl palmitates, alkyl stearates, alkyl oleates, alkyl linoleates, alkyl linolenates, alkyl behenates, and mixtures thereof.

6. 10. The vulcanizing agent composition of claim 1, wherein the alkyl ester of a saturated or unsaturated monovalent fatty acid is derived from biodiesel.

7. 2. The vulcanizing agent composition according to claim 1, wherein the alkyl ester of a saturated or unsaturated monovalent fatty acid is derived from a methyl ester of a vegetable oil, an animal oil, and / or a waste edible oil thereof.

8. The sulfur is S ８ Sulfur, cyclododeca sulfur (S １２ ), insoluble sulfur, and mixtures thereof.

9. 2. The vulcanizing agent composition according to claim 1, wherein the alkyl ester of a saturated or unsaturated monovalent fatty acid is contained in an amount of 1 to 66 parts by weight per 100 parts by weight of the sulfur.

10. 10. The vulcanizing agent composition of claim 1, further comprising one or more additives selected from vulcanization accelerators, stabilizers, antioxidants, dispersing aids, and vulcanization-accelerating aids.

11. A method for producing a vulcanizing agent composition, comprising mixing sulfur and an alkyl ester of a saturated or unsaturated monovalent fatty acid.

12. A method for producing a rubber composition, comprising mixing the vulcanizer composition according to any one of claims 1 to 10 or the vulcanizer composition produced by the method according to claim 11, and a rubber component.

13. A method for producing vulcanized rubber, comprising mixing a vulcanizer composition according to any one of claims 1 to 10 or a vulcanizer composition produced by the method according to claim 11 with a rubber component to produce a rubber composition, and then vulcanizing the rubber composition.

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