JPH0482018B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a rubber composition. More specifically, the present invention is more vulcanizable than conventional powdered sulfur, which is recovered by contacting unvulcanized rubber with hydrogen sulfide or hydrogen sulfide-containing gas and a trivalent iron salt aqueous solution as sulfur for vulcanization. This invention relates to a rubber composition containing sulfur having a high sulfur rate. [Conventional technology] Conventionally, when raw rubber is heated with sulfur added, the change in elasticity due to temperature changes, which is a disadvantage of raw rubber, is reduced, the tensile strength is increased, and the product becomes a product with excellent water and oil resistance. It is known. This operation is called vulcanization, and the substance that can change raw rubber into the above state is called a vulcanizing agent. Currently, rubber vulcanization methods can be roughly divided into methods using sulfur-based vulcanizing agents and methods using non-sulfur-based vulcanizing agents. Examples of sulfur-based vulcanizing agents include sulfur, sulfur chloride, sulfur dichloride, Examples include organic sulfides such as morpholine disulfide and polymer polysulfides, while non-sulfur vulcanizing agents include inorganic vulcanizing agents such as selenium, tellurium, magnesium oxide, litharge, zinc white, and lead peroxide. oximes, nitroso compounds, polyamines, organic vulcanizing agents such as organic peroxides, and resin vulcanizing agents. Among these vulcanizing agents, sulfur is used in natural rubber,
It is the most commonly used vulcanizing agent and is used to vulcanize diene rubbers such as SBR, isoprene rubber (IR), butadiene rubber (BR), butyl rubber (IIR), and nitrile rubber (NBR), as well as EPDM. Although the principle of rubber vulcanization is not necessarily clear,
It is presumed that the chemical crosslinking reaction forms crosslinking bonds or C--C bonds between chain rubber molecules to form a three-dimensional network structure, thereby improving physical properties. Traditionally, sulfur has been produced by carbonization of naturally occurring sulfur, which is called the pyrolysis method, but recently, most of the sulfur has been obtained from the desulfurization process of petroleum, which is carried out to prevent industrial pollution. When this sulfur is used as a vulcanizing agent, it is usually processed into powdered sulfur, sulfur flower, precipitated sulfur, colloidal sulfur, surface-treated sulfur, insoluble sulfur, and the like. By the way, when hydrogen sulfide is brought into contact with an aqueous solution containing a trivalent iron salt, sulfur is produced and 3 It is known that valent iron ions are reduced to divalent iron ions. 2FeCl ₃ +H ₂ S →2FeCl ₂ +2HCl+S↓ ……() A method of using this reaction to treat hydrogen sulfide contained in acid gas and natural gas discharged during oil refining and recover hydrogen along with sulfur. has been attracting attention recently. In this method, hydrogen sulfide-containing gas is brought into contact with an aqueous solution containing a trivalent iron salt, sulfur is precipitated and separated according to the reaction formula (), and then this separated liquid is electrolyzed as shown in the following reaction formula. In this method, divalent iron ions are regenerated into trivalent iron ions through oxidation treatment, hydrogen is generated at the same time, and the regenerated liquid is recycled for use in the treatment of hydrogen sulfide-containing gas. 2FeCl ₂ +2HCl e -→ 2FeCl ₃ +H ₂ ↑ ...() [Problems to be solved by the invention] The purpose of the present invention is to bring hydrogen sulfide or a hydrogen sulfide-containing gas into contact with an aqueous solution containing a trivalent iron salt. The objective is to provide an effective method for using the sulfur recovered. [Means for Solving the Problems] As a result of extensive research into the effective use of the sulfur, the present inventors found that when the sulfur is used as a rubber vulcanizing agent, it is more effective than conventional powdered sulfur. The inventors have discovered that the vulcanization rate is fast and that it is suitable as a rubber bulking agent, and based on this knowledge, they have completed the present invention. That is, the present invention provides a rubber characterized in that sulfur obtained by contacting an aqueous solution containing a trivalent iron salt with hydrogen sulfide or a hydrogen sulfide-containing gas is blended into an unvulcanized rubber as a vulcanizing agent. A composition is provided. The present invention will be explained in detail below. In the rubber composition of the present invention, the sulfur used as a vulcanizing agent is obtained by contacting an aqueous solution containing a trivalent iron salt with hydrogen sulfide or a hydrogen sulfide-containing gas, and recovering and separating the precipitated sulfur. It is. As the aqueous solution containing the trivalent iron salt,
Examples include ferric chloride aqueous solution, ferric sulfate aqueous solution, ferric phosphate aqueous solution, and the like. These ferric salt aqueous solutions preferably contain free hydrochloric acid, sulfuric acid, phosphoric acid, etc., and may or may not contain ferrous salts. It doesn't have to be. Among these ferric salt aqueous solutions, ferric chloride aqueous solutions containing free hydrochloric acid are particularly suitable. The content of ferric salt is usually selected in the range of 0.1 to 5 moles per kg of water, and the content of free acid is preferably in the range of 0.5 to 15 moles per kg of water. Further, the gas to be treated may be hydrogen sulfide alone or a mixed gas of hydrogen sulfide and other gases such as hydrogen, carbon monoxide, carbon dioxide, hydrocarbons, ammonia, and the like. As a method for bringing the aqueous solution containing a trivalent iron salt into contact with hydrogen sulfide or the hydrogen sulfide-containing gas, a method commonly used in gas absorption by a liquid can be used. The temperature at this time is usually from room temperature to 100°C, preferably in the range of 50 to 90°C. If the gas absorption temperature is outside this range, the absorption rate of hydrogen sulfide will become unfavorable, and if the temperature is low, the produced sulfur will tend to become rubbery. In this way, when hydrogen sulfide is absorbed into the aqueous solution containing the trivalent iron salt, the hydrogen sulfide is oxidized to produce sulfur, as shown in the reaction equation () above, while 3 The valent iron ion is reduced to 2
It becomes a valent iron ion. Next, the generated sulfur is separated and recovered, but solid sulfur may be separated by centrifugation or filtration, or heated to about 120 to 150℃ if desired. A method may also be used in which the molten sulfur is separated by means such as liquid separation. In this way, the separated and recovered sulfur is usually
Finely ground to a size that can pass through a 200 mesh sieve,
It is used in the rubber composition of the present invention as a vulcanizing agent. On the other hand, the iron salt aqueous solution from which sulfur has been separated and recovered is generally cooled as desired and filtered to remove precipitates such as ammonium salts, and then subjected to electrochemical treatment, or processed into potassium chloride, lithium chloride, ammonium chloride, etc. By adding an inorganic salt and blowing oxygen or an oxygen-containing gas such as air,
After oxidizing divalent iron ions to trivalent iron ions and regenerating them, they are recycled and used to absorb hydrogen sulfide. When the oxidation is carried out by electrochemical treatment, divalent iron ions are regenerated into trivalent iron ions and hydrogen is generated at the same time, as shown in the reaction formula (). The rubber composition of the present invention is one in which the powdered sulfur thus obtained is blended with unvulcanized rubber as a vulcanizing agent, and the amount of blending is usually 100 parts by weight of unvulcanized rubber. The amount is selected in the range of 0.1 to 60 parts by weight. The preferred amount varies depending on the type of rubber product desired; for example, 0.3 to 4 parts by weight for soft natural rubber products, and 30 parts by weight for hard rubber products.
~60 parts by weight is blended. Examples of the unvulcanized rubber used in the rubber composition of the present invention include natural rubber, SBR, IR,
Diene rubber such as BR, IIR, NBR, EPDM
Examples include. In addition to the vulcanizing agent, the rubber composition of the present invention contains various additives that are normally used in rubber compositions, such as vulcanization accelerators, vulcanization accelerators, reinforcing agents,
Fillers, anti-aging agents, anti-scorch agents, etc. can be added as desired. Examples of the vulcanization accelerator include guanidine type such as diphenylguanidine and diorthotolylguanidine, aldehyde-amine type such as n-butyraldehyde-aniline condensate, aldehyde-ammonia type such as hexamethylenetetramine, etc.
-Mercaptobenzothiazole, dibenzothiazyl disulfide, 2-(2,4-dinitrophenylthio)benzothiazole, 2-(N,N-diethylthiocarbamoylthio)benzothiazole,
Thiazole series such as 2-(4'-morpholinodithio)benzothiazole, N-cyclohexyl-2-
Benzothiadylsulfenamide, N,N-dicyclohexyl-2-benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, N-t-butyl-2-benzothiazylsulfenamide Sulfenamide series such as thiocarbanilide, diorthotolylthiourea, thiourea series such as ethylenethiourea, diethylthiourea, dibutylthiourea, trimethylthiourea, tetramethylthiuram monosulfide,
Thiuram series such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, sodium dimethyldithiocarbamate, sodium diethyldithiocarbamate, di-n-butyldithiocarbamic acid Sodium, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, di-n-
These include dithiocarbamate series such as zinc butyl dithiocarbamate, zinc ethyl phenyl dithiocarbamate, piperidine pentamethylene dithiocarbamate, pipecoline methylpentamethylene dithiocarbamate, and xanthate series such as sodium isopropyl xanthate and zinc isopropyl xanthate. They may be used alone or in combination of two or more. Examples of vulcanization accelerating aids include inorganic aids such as zinc white, zinc carbonate, magnesium oxide, litharge, and calcium hydroxide, stearic acid, oleic acid, lauric acid, zinc stearate, di-n-butylamine, and dicyclohexyl. amine, mono,
Examples include organic auxiliaries such as di-, triethanolamine, and diethylene glycol, which may be used alone or in combination of two or more. Examples of reinforcing agents include channel black,
Carbon blacks such as furnace blacks and thermal blacks, white carbon (silica),
Basic magnesium carbonate, activated calcium carbonate, inorganic reinforcing agents such as ultrafine magnesium silicate, high styrene resin, cyclized rubber, phenol, etc.
Examples include organic reinforcing agents such as formaldehyde resins, lignin, and amino resins mainly composed of modified melamine resins, and each of these may be used alone or in combination of two or more. Examples of fillers include calcium carbonate, clay, talc, silica, diatomaceous earth, silica sand, pumice powder, slate powder, mica powder, asbestos, alumina white, aluminum sulfate, barium sulfate, calcium sulfate, molybdenum disulfide, and graphite. Examples include inorganic fillers such as carbon fiber, glass fiber, and microballoons, and organic fillers such as recycled rubber, rubber powder, ebonite powder, wood flour, cork powder, polyvinyl alcohol fiber, and cellulose powder. Alternatively, two or more types may be used in combination. Examples of anti-aging agents include N,N'-diphenyl-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine,
N,N'-di-2-naphthyl-p-phenylenediamine, N-(1,3-dimethylbutyl)-N'-
p-phenylenediamine series such as phenyl-p-phenylenediamine, 2,2,4-trimethyl-
Polymers of 1,2-dihydroquinoline, quinolines such as 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, 2,5-di-t-amylhydroquinone, 2,5-di- Hydroquinone derivatives such as t-butylhydroquinone and hydroquinone monomethyl ether, 2,6-di-t
-butyl-4-methylphenol, 2,6-di-
t-Butyl-4-ethylphenol, butylhydroxyanisole, 2-(1-methylcyclohexyl)-4,6-dimethylphenol, 6-(4-
hydroxy-3,5-di-t-butylanilino)
-2,4-bisoctyl-thio 1,3,5-triazine, n-octadecyl-3-(4'hydroxy-3',5'-di-t-butylphenyl)propionate, monophenolics such as styrenated phenols, 2,2'-methylenebis(4-methyl-6
-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol),
4,4'-methylenebis(2,6-di-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), 1,1-bis(4-hydroxyphenyl) cyclohexane,
1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane , tetrakis [methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]
Polyphenols such as methane, 4,4'-thiobis(6-t-butyl-3-methylphenol),
4,4'-thiobis(6-t-butyl-o-cresol), 2,2'-thiobis(6-t-butyl-4
- thiobisphenols such as methylphenol) or dilaurylthiodipropionate,
Distearylthiodipropionate, dimyristylthiodipropionate, 2-mercaptobenzimidazole, 2-mercaptomethylbenzimidazole, nickel dibutyldithiocarbamate, 1,3-bis(dimethylaminopropyl)-
Examples include 2-thiourea, tris(nonylphenyl)phosphite, waxes, etc., and each of these may be used alone or in combination of two or more. Examples of the scorch inhibitor include organic acids such as phthalic anhydride, salicylic acid, benzoic acid, and malic acid, N-nitrosodiphenylamine, N-nitrosophenyl-β-naphthylamine, and N-(cyclohexylthio)phthalimide. Each of these may be used alone or in combination of two or more. In the rubber composition of the present invention, there is no particular restriction on the amount of these additives blended, and they can be blended in the amounts used in conventional rubber compositions, but usually 100 parts by weight of unvulcanized rubber. The total amount is about 10 to 500 parts by weight. The rubber composition of the present invention can be prepared, for example, as follows. That is, the unvulcanized rubber is first masticated to facilitate the subsequent kneading operation, if necessary. In this case, as a mastication accelerator, for example, zinc salt of β-naphthyl mercaptan, xylyl mercaptan, pentachlorothiophenol,
2,2'-dibenzamide diphenyl disulfide and the like can also be used. Next, a vulcanizing agent and various additives are kneaded into this unvulcanized rubber using, for example, an open mill or a Banbury mixer to prepare a rubber composition. The rubber composition of the present invention thus prepared is vulcanized and molded by a vulcanization molding method depending on the purpose of the rubber product. Vulcanization is usually carried out by heating at a temperature in the range of 100 to 200°C for about 1 minute to 1 hour. The rubber composition of the present invention has a considerably faster vulcanization rate than a rubber composition having the same composition except that ordinary powdered sulfur is used as a vulcanizing agent, and the physical properties of the molded article are not inferior in any way. [Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way. Production example 1 Ferric chloride 1.2 mol/Kg-H ₂ O, ferrous chloride 0.8
An aqueous solution of mol/Kg-H ₂ O and hydrochloric acid 5 mol/Kg-H ₂ O flows from the top of the absorber at a flow rate of 100 c.c./min, and hydrogen sulfide-containing gas (H ₂ S30%) flows from the bottom of the absorber. , H ₂ 70%) was flowed at a flow rate of 600 c.c./min, and countercurrent contact was carried out at 60°C. A suspension containing sulfur powder produced by the reaction was passed through a filter, washed with water, and dried under reduced pressure to obtain powdered sulfur. This powdered sulfur was crushed into a powder of less than 200 mesh by lightly crushing it in a mortar. The purity of this sulfur is 99.9%
It contained 100 ppm of iron and 150 ppm of chlorine (powdered sulfur). Production Example 2 In Production Example 1, 0.4 mol/Kg of ferric chloride
-H ₂ O and ferrous chloride were changed to 1.6 mol/Kg-H ₂ O, but the same procedure as Production Example 1 was carried out. Powdered sulfur almost the same as Production Example 1 was obtained, and the iron content was The amount of chlorine was 95 ppm, and the chlorine content was 135 ppm (powdered sulfur). Production Example 3 In Production Example 1, 0.5 mol/Kg of ferric chloride
Production Example 1 except that -H ₂ O, ferrous chloride was changed to 0.5 mol/Kg-H ₂ O, and hydrochloric acid was changed to 7 mol/Kg-H ₂ O.
When carried out in the same manner as in Production Example 1, powdered sulfur was obtained, with an iron content of 90 ppm and a chlorine content of 100 ppm (powdered sulfur). Production example 4 Ferric chloride 1.6 mol/Kg-H ₂ O, ferrous chloride 0.4
An aqueous solution of mol/Kg-H ₂ O and 4 mol/Kg-H ₂ O of hydrochloric acid is flowed from the upper part of the absorber at a flow rate of 100 c.c./min, and hydrogen sulfide and n-butane-containing gas ( Hydrogen sulfide (27%, n-butane 25%, hydrogen 48%) was flowed at a flow rate of 600 c.c./min, and powdered sulfur was precipitated by countercurrent contact at 60°C. This sulfur suspension was absorbed and filtered, washed with water, and
Sulfur powder was obtained by drying under reduced pressure at °C (powdered sulfur). Examples 1 to 8, Comparative Examples 1 and 2 Rubber compositions were produced using unvulcanized rubber, additives, and powdered sulfur, and the vulcanization status and mechanical strength of the molded products were measured. The formulation is based on the synthetic rubber SBR test method (JIS
K 6383), and two 6-inch rolls were used for kneading. Mooney viscosity was measured in accordance with JIS K 6300 using a Mooney viscometer manufactured by Shimadzu Corporation SMV-200, and the progress of the vulcanization reaction was measured in accordance with JIS K 6300 using a JSR Curelastometer type manufactured by Japan Synthetic Rubber. It was measured using In addition, tests on molded products were conducted in accordance with JIS K 6301, and tensile tests were conducted using Autograph IS- manufactured by Shimadzu Corporation.
Measurement was performed using a 5000 model tensile tester at a tensile speed of 500 mm/min. The results are shown in Tables 1 and 2.

【table】

【table】

【table】

〔Effect of the invention〕

The rubber composition of the present invention is one in which powdered sulfur recovered by contacting an aqueous trivalent iron salt solution with hydrogen sulfide or a hydrogen sulfide-containing gas is blended with unvulcanized rubber as sulfur for vulcanization, and includes: Compared to compositions containing ordinary powdered sulfur, the vulcanization rate is faster, and the physical properties of the resulting molded products are comparable.

Claims (1)

[Claims] 1. Sulfur obtained by contacting hydrogen sulfide or a hydrogen sulfide-containing gas with an aqueous solution containing a trivalent iron salt is blended into unvulcanized rubber as a vulcanizing agent. Rubber composition. 2. The amount of sulfur added per 100 parts by weight of unvulcanized rubber,
The composition according to claim 1, wherein the amount is 0.1 to 60 parts by weight.