TW527388B - Mixtures of carboxyl group-containing diene rubbers with fillers - Google Patents

Abstract

The invention relates to rubber mixtures containing diene rubber with a concentration of carboxyl groups of 0.1 to 2 wt.% and a glass transition temperature of -120 to -50 DEG C and their mixtures with fillers, optionally further rubbers and rubber auxiliary substances and vulcanisates prepared therefrom. Rubber mixtures according to the invention are suitable for producing highly reinforced, abrasion-resistant moulded items, in particular for producing tire treads which have a particularly high resistance to wet skidding, a high abrasion resistance and a low rolling resistance and also for tire sidewalls with especially good fatigue resistance.

Description

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 527388 A7 B7

5. Description of the invention (1) Field of the invention: The present invention provides a rubber mixture containing one or more carboxyl groups or salts thereof having 0.1 to 2% by weight of bonded carboxyl groups and having a glass transition temperature of -12 °. 〇 to -50. 〇 rubber, and one or more fillers, optional other 5 rubber as well as rubber auxiliary substances and vulcanizing agents. The rubber mixture according to the present invention is suitable for manufacturing highly reinforced, abrasion-resistant moldings, especially for preparing tires with high resistance to wet skid, abrasion, and low rotation, and the tire edges have particularly good fatigue resistance. . 10 Background of the Invention: Anionically polymerized solution rubbers containing double bonds, such as solution-like polybutadiene and styrene / butadiene rubber, have the advantage over corresponding emulsion rubbers that they can produce rubber soles with low rotation resistance. . This advantage is based in particular on the ability to control the ethylene content and glass transition temperature and the molecular branches associated with it. With its unique wet skid resistance and low rotation resistance of tires, it can be practically used. Accordingly, U.S. Patent No. 5,227,425 discloses a tire sole made from SBR rubber solution and silica. In order to further improve its characteristics, various methods to improve the terminal functional group have been developed, such as the dimethylaminopropylpropenoic acid amide disclosed in European Patent No. A334,042, or such as European Patent The silyl ether disclosed in A447, 〇66. However, due to the high molecular weight of rubber, the weight percentage of terminal functional groups is small, so it can only slightly affect the interaction between filler and rubber molecules. In addition, the purpose of the present invention is to provide two functional groups having a relatively high concentration effective for the interaction of fillers and unique low glass transition temperatures. The paper size is applicable to the Chinese National Standard (CNS) A4 (210 X 297 mm) ( (Please read the notes on the back before filling out this page)

Α7 五 Β7 Description of invention 10 15 20 olefin rubber. U.S. 2,662,874 discloses a method for preparing a polymer carbonate elastic material having a concentration ranging from 0.0000 to 0.33 metal equivalents per 100 rubbers, which has a range due to its inherent sensitivity to the hydrolysis of metal salts. Elastic materials with extremely wide carboxyl content are not suitable for the tires of the present invention. In addition, DE-OS 2,653,144 describes the preparation of an isobutadiene rubber containing an end group (3.9 to 8.9% by weight of a carboxyl group). Due to the high concentration = ethylene and fluorene, and the unfavorable mud blocking properties, the glass transition temperature of these rubbers is too high (over -5 (TC), so it is not a substitute for winter polybutene rubber on the bottom and edges of tires. Therefore, the present invention intends to provide a rubber compound containing a carboxyl group, so that tires having improved resistance, hiccup resistance, lower rotational resistance, high mechanical strength, and improved abrasion resistance can be manufactured. Therefore, The present invention provides a rubber mixture containing one or more = rubbers having 0.1 to 2% by weight of a bonded carboxyl group or a salt thereof and having a glass transition temperature ^ between 120 C and -50 C, and one or more fillers. Its content is from 10 to 500 parts by weight based on 100 parts by weight of rubber. A preferred rubber mixture according to the present invention has a bonded carboxyl group or a salt thereof of 0.001 to 丨 °° / ° and a glass transition temperature of -12 ° To _70 and other rubbers, and diolefins (ethylene content) with a concentration of 0 to 50% by weight (especially 丨 to 15%), and 30 to 100% by weight (90 to 100%) Zhongli%) of cis_1,4_ content, which The average molecular weight is between 50,000 and 2,000, _, preferably between rigid, _ and i, and the surface, and its Muni viscosity ML1 + 4 (100 ° C) is between 10 and 200. , Preferably 30 to 15 ％. -4- This paper size applies to China National Standard (CNS) A4 (21〇X 297mm) (Please read the precautions on the back before filling this page) ·-•% 527388 A7 _ B7 V. Explanation of the invention (3) The glass transition temperature can be measured by a known method, for example, using a differential scanning caliper (DSC, heating rate 20 K / s). The concentration of the carboxyl group can also be known by a known method. Measurements such as free acid titration, photometer, elemental analysis, etc. 5 The rubber used in the rubber mixture of the present invention according to the present invention is preferably prepared by coordination catalyst polymerization or anionic solution polymerization. The potential catalysts can be understood as Zeigler-Natta catalysts, coordination catalysts and single metal catalyst systems. The coordination catalysts are preferably nickel, starting, titanium, or convergence. It is used for anionic liquid polymerization. The catalyst is mainly based on alkali metals or alkaline earth metals, such as n-butyllithium. In addition, you can use Randomized control agents known to control the microstructure of the polymer. These classes are liquid polymerization process are known and have been introduced, for example, Elsevier in 1989 I. Franta

As disclosed in Elastomers and Rubber Compounding Materials on pages 113-131, and Houbem-Weyl in Methoden der Organischen Chemie in 1961 (vol. XIV / 1 15 pages 645-673) and 1987 (vol · E20 pages 114-134), Thieme Verlag, published in Stuttgart. The diene used for the polymerization according to the present invention is 1,3-butadiene, isoprene-m-diene, 1,3-pentadiene, 2,3-dimethylbutadiene, 1-ethylene -20-20 1,3-butadiene and / or 1,3-hexadiene. Among them, it is preferable to use ι, 3-butadiene and isoprene-m-diene. The carboxyl group may be added to a metalized liquid rubber by adding a carboxyl group-providing compound such as carbon dioxide, or the final rubber may be treated with a Wei group-containing compound such as a carboxyl-containing thiol in a subsequent reaction. This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm) (please read the precautions on the back before filling out this page). It is printed by the Intellectual Property Bureau's Consumer Cooperatives of the Ministry of Economic Affairs and printed by 527388 A7. 10

HS-R ^ COOX ⑴ Among them,-is represented by 6-stranded silk, which can be optionally replaced by == Bu, or inserted with nitrogen, oxygen, or sulfur atom c6-c12 stretched aromatic group, and X represents a hydrogen atom Or metal or ammonium ions.丨 丨 丨 丨 丨-丨 —I 丨 丨 · Can ^ · 丨 I (Please read the notes on the back before filling this page) Order: 15 This method is another subject of the present invention. C ^ 36 stretched wire can be understood as any straight, cyclic or branched chain of 1 to 36 carbon atoms known to those skilled in the art, such as methylene, stretched ethyl, N-propyl, n-isopropyl, n-butyl, i-butyl, tertiary butyl, n-pentyl, i-pentyl, n-pentyl, n-hexyl, cyclohexyl, i-hexyl , Heptyl, hexyl, hexyl, hexyl, hexyl, hexyl and hexyl. The carboxylic thiol of formula (I) is preferably hydrogen thioacetic acid, 2-thiolpropionic acid (4-thiolactic acid), 3-thiolpropionic acid, 4-thiolpropionic acid, and alcoholthiol. Monoacids, thiol octanoic acid, 2-thiol succinic acid, and alkali, alkaline earth metal or ammonium salts of these acids. Among them, 3-thiol-propionic acid, thiol-butyric acid, 2_ 6- This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)

Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 20 527388 A7

Thiol-based succinic acid, 2- and 4-thiol benzoic acid and their lithium, sodium, potassium, magnesium, calcium or amine salts are preferred. 3-Mercaptopropionic acid and its lithium, sodium, potassium magnesium, calcium or amine salts are optimal. In general, the reaction of carboxy mercaptan with liquid rubber is preferably in a solvent such as hydrocarbons such as pentane, hexane, cyclohexane, benzene, and / or benzene 'at a temperature of 40 to 150. 〇, in free radical initiators such as peroxide (such as dilauryl peroxide, azo initiators, such as azobisisobutyronitrile, benzyl alcohol silyl ether) or in photoinitiators and It is performed in the presence of visible light or ultraviolet light. Preferred free radical initiators are difluorenyl peroxides, such as dodecafluorenyl 10-based peroxide, dilauryl peroxide, di · (3,5,5-trimethylcyclohexyl peroxide) Substances and peroxyketals, such as u _: _ (tertiary butyl peroxy 3,3,5-trimethylcyclohexane, di- (tertiary butyl peroxy) butane. Dosage of carboxy mercaptan It can be calculated from the concentration of bonded carboxyl groups or the salt required for liquid rubber used in rubber mixtures. 15 The carboxylate can also be added to the rubber after adding the carboxylic acid group to neutralize it. According to the present invention, it is suitable for rubber The fillers of the mixture can be any well known in the rubber industry, these include activated and inactivated fillers. The following may be mentioned: 20-Highly dispersed silica is precipitated by silicate solution or _ It is prepared by flame hydrolysis of silicone, and has a surface area of 5 to 1,000 m 2 / g, preferably 20 to 400 m 2 / g (BET surface area), and the main particle size is 10 to 400 nm. Silica can also be mixed with any other metal oxide, such as aluminum, magnesium, calcium, barium, zinc, zirconium or titanium oxide. The paper size of this paper applies the Chinese National Standard (CNS) A4 specification (210 X 297 public love) f Please read the notes on the back before filling out this page} · Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economy ); Synthetic crushed stone such as crushed acid salt or earth metal oxalate such as dream acid or oxalic acid, which has a BET surface area of 20 to 400 m 2 / g, and the main particle size is 10 to 40 nanometers M; 5-natural silicates such as high-territory and other naturally-produced silicas, ...-glass fiber and surface products (good, good) or glass beads; -... metal oxides, such as oxides , Calcium oxide, magnesium oxide, aluminum oxide;-metal carbonates, such as magnesium carbonate, calcium carbonate, zinc carbonate, · metal hydroxides, such as aluminum hydroxide, light magnesium oxide; 10 ... carbon black. Carbon black used here Manufactured from lamp black, furnace black or channel black, with a BET surface area of 20 to 200 m² / g, such as SAF, ISAF, HAF, FEF, or GPE carbon black; -... rubber gel, especially Those based on polybutadiene, butadiene / styrene copolymer, butadiene Diene / acrylonitrile copolymer and polychloroprene. 15 interspersed silica and / or carbon black are preferably used as fillers. The mentioned fillers are printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs. It can be used separately or as a mixture. In the preferred embodiment, the rubber mixture contains off-white fillers, such as highly dispersed silica and carbon black fillers, where the mixing ratio is 20% off-white filler. The carbon black is 0.05 to 20, preferably 0.1 to 10. The amount of the filler is 10 to 5000 parts by weight relative to 100 parts by weight of rubber, and 20 is preferably used. Up to 200 parts by weight. The rubber mixture according to the present invention may contain one, two, three or this paper size. Applicable to China National Standard (CNS) A4 (210 X 297 mm). Printed by the Consumer Cooperative of Intellectual Property Bureau of the Ministry of Economic Affairs 527388 A7 B7 V. Description of the invention (7) Many different carboxyl-containing liquid rubbers may also contain other rubbers such as natural rubber or synthetic rubber. Preferred synthetic rubbers are mentioned in the following documents: W. Hoffmann, Kautschuk-technologie, Gentner Verlag, Stuttgart 5 1980 and I. Franta, Elastomers and Eubber Compounding

Materials, Elsevier, Amsterdam, 1989. These synthetic rubbers include: BR polybutadiene ABR butadiene / CrC4 alkyl acrylate copolymer CR polychloroprene IR polyisoprene-diene SBR styrene / butadiene copolymer, styrene content 1-60, preferably 20-50% by weight, weight%, IIR isobutene / polyisoprene-m-diene copolymer NBR butadiene / acrylonitrile copolymer, acrylonitrile content 5-60, preferably 10- 40% by weight, HNBR partially hydrogenated or fully hydrogenated NBR rubber EPDM ethylene / propylene / diene copolymers and mixtures of these rubbers. In order to make tires for vehicles, natural rubber, emulsified SBR and liquid SBR 10 glass transition temperatures above -50 ° C can optionally be modified with silane ethers or other functional groups, for example according to EP-A 447,066, Polybutadiene rubber with a high 1,4-cis content (greater than 90%), which has been manufactured using catalysts based on nickel, cobalt, titanium, or <RTIgt; and < / RTI > Butadiene, and its blending is particularly interesting. 15 In addition to the rubber mixture according to the present invention, in addition to one or more carboxyl-containing rubbers having a glass transition temperature between -110 ° C and -50 ° C, the other rubbers are -9-^^: The dimensions are applicable to Chinese national standards (CNS ) A4 size (210 X 297 mm) '(Please read the notes on the back before filling this page) Order: 527388 A7 B7

V. Description of the invention (8) (Please read the notes on the back before filling out this page) Selected from natural rubber, polyisoprene-m-diene and styrene / butadiene with a styrene content between 10 and 50 weight Olefin copolymer. These additional rubbers are used in an amount of 0.5 to 95 weight based on the weight of the entire rubber mixture. It is preferably 40 to 90% by weight. Again, these additional = rubber ° = 5 can be calculated from the rubber mixture according to the invention. Obviously, the rubber compound according to the present invention may also contain other rubber adjuvants for specific uses, such as cross-linking a vulcanized substance manufactured from a rubber compound or an agent capable of improving a vulcanized compound manufactured from a rubber compound ^: ignore characteristic. 10% or sulfur-providing compounds' and free-radical crosslinking agents such as organic peroxides can be used, such as crosslinking agents. Sulfur is preferably used as a crosslinking agent. Furthermore, as mentioned previously, the rubber mixture according to the invention may additionally contain auxiliary substances, such as known reaction accelerators, antioxidants, heat stabilizers, light stabilizers, anti-ozonants, processing aids, plasticization Agents,! 5 thickeners, foaming agents, colorants, pigments, soils, extenders, organic acids, retarders, metal oxides and activators. The rubber adjuvant according to the present invention is generally used in the amount disclosed, and the amount printed in the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs is measured based on the most recent use of the rubber mixture. For example, the rubber adjuvant is generally used in an amount of 2 to 20 to 70 parts by weight relative to 100 parts by weight of rubber. In the rubber mixture according to the invention, it is particularly advantageous to use an additional filler activator which is filled with highly activated stone spar. The preferred filler activator is a surface-containing tester, especially a bis (trisoxy-oxysulphonyl-based) polysulfide, such as in DE 2, ⑷, 159 and de 2,255,577 -10- Paper size applies to Chinese national standard millimeters) 527388 Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs A7 V. Invention description (9). In addition, filaments and / or polymers with fine surfaces mentioned in DE 4,435,311 and EP 67,347 are also suitable. Thiol-based thiotrisyloxybenzenes, in particular thiol-propyltriethoxylithium and thiocyanoylsilyl ethers (see DE 19,544,469) can also be used. 5 The amount of the filler activator is usually 0.1 to 15 parts by weight relative to 100 parts by weight of the rubber. The rubber mixture according to the present invention can also be used, for example, by mixing liquid rubber containing a base group and corresponding fillers and optional other rubbers and other rubber auxiliary substances' with a suitable mixing apparatus, such as a mixer, a thrower or 10 Extruder. According to the preparation of the rubber mixture of the present invention, it is preferred to first polymerize the above-mentioned monomers in solution, pour the base into a liquid oak, and then after the polymerization reaction is completed, the carboxyl group is introduced. The liquid rubber is mixed with suitable fillers, other optional rubbers and other rubber 15 rubber auxiliary substances in a solvent, made into a plasticizer, and then removed with hot water and / or steam at 50 to 200 ° C. The solvent is preferably under vacuum. The subject matter also provides the use of rubber mixtures according to the present invention to make various types of molded articles, particularly for the manufacture of tires, especially tire bottom surfaces and tire edges. Example: Example 1: Take 6.25 grams of 3-thiolactic acid and 1 grams of dilauryl peroxide, add 80 C containing 500 grams of polybutene rubber solution, CB45NF (Bayer, lithium ____- 11- this paper Standards are applicable to China National Standard (CNS) A4 specifications (21〇X 297 public love) ------- (Please read the precautions on the back before filling this page)

tST 527388 A7 B7 V. Description of the invention (1G) state, cis-1,4- content about 40%) in 4 liters of cyclohexane. Next, the mixture was stirred at 80 ° C for another 7 hours. Then, 2,5 antioxidant Vulkan 0x 4020 (Bayer, Germany) and 101.3 g of aromatic mineral oil Enerthene 849_ 1 (BP) ′ were added and the solvent was distilled out with therapeutic gas (100-110 C). After drying at 70 ° C under 5 vacuum ', 593 grams of rubber spread in 20 phr of mineral oil can be paid. The sulfur content of this rubber is 0.3% by weight, the Wei Ke content is 0.5% by weight (based on rubber), and the viscosity is ML 1 + 4 (100.05, cis-1, 4-content 40 %, Glass transition temperature: -88 ° C. 10 Example 2: The following rubber compound was prepared in a 1.5-liter kneader (mixing time: 5 minutes, injection temperature 150 ° C). After that, sulfur and acceleration Add the agent to the grinder (50 ° C). Ϋ I ϋ an a_ ^ i 1¾ ϋ n ϋ (Please read the precautions on the back before filling this page) Ίδτ_ Printed by the Consumers ’Cooperative of the Intellectual Property Bureau of the Ministry of Economy 2. Comparative Example 2. A Example 2.1 Mixing in a kneader: Buna VSL 5025 · 1 (37,5 phr mineral oil extended L-SBR, Bayer, Germany) 61.9 61.9 Natural rubber 10 10 Polybutene rubber Buna CB 45 (Bayer) 45 0 According to the example 1 Carboxyl-containing rubber (20 phr oil content) 0 54 Mineral oil Enerthene 1849-1 (BP) 20 11 Shi Xi Shi Vulkasil S (Bayer, Germany) 70 70 Shi Xi Jia burned Shi Xi (69 (Degussa Huls)) 6 6 Carbon black Corax N121 (Degussa Huls) 10 10 Zinc oxide 3 3 Stearic acid 1 1 Protected wax Antilux 654 (Rheinchemie antioxidant Vulkanox HS (Bayer, Germany) 1 1 Antioxidant VulkanoxHS (Bayer, Germany) -12- 1 1 This paper size applies to Chinese National Standard (CNS) A4 (210 X 297 mm) 527388 A7 _B7 V. Description of the invention (n)

On the mill admixed N-cyclohexyl M-phenylthiazolium sulfenamide Vulkacit 1.8 1.8 CZ (Bayer, Germany) Diphenylguanidine Vulkacit D (Bayer, Germany) 2 2 Sulfur 1.5 1.5 Next, the rubber mixture was vulcanized at 170 ° C at high temperature 15 minutes. The following are the sulfide characteristics obtained. Comparative Example 2.A Example 2.1 Tensile strength (Mpa) 16.8 18.2 Elongation at break (%) 450 330 Modulus at 100% 2.4 2.9 Modulus at 300% elongation 9.5 16.3 Rebond at 70 ° C Elasticity (%) 54 63 Hardness (shore A) 66 66 tan delta at 70 ° C 0.138 0.108 (Please read the precautions on the back before filling this page) Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs and then bonded Elasticity and tan delta, experimental data confirm that there is significantly lower dynamic damping at 70 ° C, which is actually related to the reduction of the tire's rotational resistance. 10 Example 3: Preparation of a mixture of precipitated silica and a carboxyl-containing BR rubber precursor: Using the method of Example 1, 4 liters of cyclohexane with 500 g of BR rubber Buna CB 65 dissolved at 80 ° C and 12.5 g of 3-thiolactic acid reacts with dilauric peroxide. Response time: 5 hours. At this time, 36% of 3-sulfur -13- This paper size is in accordance with Chinese National Standard (CNS) A4 specification (210 X 297 mm) 527388 A7 _____B7__ 5. Description of the invention (12) The generation of lactic acid has been reacted. The carboxyl group content of the polymer was 0.38% by weight. Then, at 75C, add 25 grams of stabilizer Vuikanox® 4020 (Bayer, Germany), 189.5 grams of aromatic mineral oil Renopal @ 450 (Fuchs Mineraimwerke), and 4.05 grams of highly active precipitated silicon while stirring. Stone 5 Vulkasilos (nitrogen surface area of about 180 m square / gram), and smashed at this temperature for about 30 minutes and 4 li 'until these ingredients are evenly distributed. Then, the solvent is removed by using the vapor (10 (MlG ° c)) through the mixture. At this step, the reaction volume is externally added to this reaction || plus_75_8Gt :. Finally, the wet solids are removed by a sieve to finely divide it The product was filtered through a stone filter, and the product was dried under a vacuum of 10 W at 65 ° C. As a result, 1,090 g of a brown stone stone / rubber matrix mixture was obtained (99% of the theoretical value). The wastewater did not contain any silicon. Comparative Example 3.A: This example was carried out using the same procedure as described in Example 3, in which 500 grams of BR rubber Buna CB 65 and Vulkanox'OSO were used to dissolve 500 grams of employees. Printed by the cooperative 丨 ίΓ—— · Packing! (Please read the precautions on the reverse side before filling out this page) Shenghuan has been burned at 75C and 400 g of highly active precipitated stone eve stone Vuikasii © s. Then, use The solvent was removed by the vapor of the mixture (1_110.0), and the reaction vessel was heated to 75_80 ° C simultaneously and externally in this step. Finally, the moist solids were removed and the finely divided silica was filtered through a sieve Out of 20, and the product was dried in a vacuum environment at 65 C. Results Obtained 597 grams of heterogeneous silica / rubber matrix mixture (66% of theory). Wastewater contains a large amount of silica (approximately 75% of the amount used). -14- This paper applies Chinese National Standard (CNS) A4 Specification (210 X 297 mm) Application date

The above columns are filled by this bureau.) Intellectual Property of the Ministry of Economic Affairs / V7a (Printed by the Industrial and Consumer Cooperatives | Patent Specification New Type of Invention% Chinese Mixture of Carboxylic Diene Rubber and Filler in English Mixtures of carboxyl group-containing diene rubbers with fillers Name 1. Thomas Thomas SCHOLL 2. Ding Qiujiang Jtirgen TRIMBACH ^ Inventor-Creator Nationality Residence and Residence 1.-2. Germany (Germany) 1. Alte Wipperfurther Str. .24 a, 51469 Bergisch Gladbach, Germany 2. Wupperstr. 73, 50859 κδΐη, Germany Name (Name) Germany Bayer Aktiengesellschaft Nationality Germany (Germany) III. Applicant Residence, Residence (Office) D 51368 D 51368 Bayer Industrial Park, Leverkusen City, Germany Leverkusen, Bayerwerk, Federal Republic of Germany Representative Name Dr. Rolf Braun Dr. Klaus Reuter Dimensions of this guideline paper are applicable to China National Standards (CNS) secret (210x297 public envy) Patent Application No. 8910794 No. 0 ROC Patent Appln. No. 89107940 Chinese Manual Correction Page-Attachment (3)

Amended Pages of the Chinese Specification-Encl.Hin (Amended and Submitted on 9¼, 1991) ~~ (Amended & Submifi ^ d on September, 2002) 527388

Claims (1)

527388 Announcement A8 B8 C8 D8 VI. Application for Patent Scope Patent Application No. 89107940 ROC Patent Appln. No. 89107940 Amended Application Special Scope Chinese Text-Attachment (^ 一) Amended Claims in Chinese-Encl.d) (Submitted on September 2002) 1. A rubber mixture containing one or more carboxyl groups or salts thereof with O i to 2% by weight and a glass transition temperature between _12 (rc to _5〇C A dilute rubber, and one or more fillers, the content of which is 10 to 500 parts by weight relative to 100 parts by weight of rubber. 2. The rubber mixture according to item 1 of the patent application, characterized in the diene rubber It is constructed from a diene. 3. A method for producing a rubber having a bonded carboxyl group of from 0 to 2% by weight, characterized in that after the polymerization reaction in a solution, the rubber is allowed to react with the weidyl mercaptan represented by formula ⑴ The reaction is performed in the presence of a selected free radical initiator: HS-R ^ COOX (I) where R1 represents a straight-chain, branched-chain or cyclic Cl_c36 alkylene group printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economy. Optionally be 3 extra Group, or insert nitrogen, oxygen or sulfur atom 'or C6-C12 aryl group, and X represents hydrogen atom or metal or ammonium ion. 4. If the rubber mixture of item 1 of the scope of patent application, its purpose is to use To prepare moulds in various forms. 5. For example, the rubber mixture of item 丨 in the scope of patent application is used to prepare tires. -15-89206c 297 mm) This paper size applies to China National Standard (CNS) A4 specifications ( 210: