Rubber compound for manufacturing medical sealing element and preparation method thereof

Abstract

The invention discloses a rubber compound for manufacturing a medical sealing element and a preparation method of the rubber compound, and relates to the technical field of rubber. The rubber compound for manufacturing the medical sealing element is prepared by mixing the rubber composition, the composite modifier and the like; the rubber composition comprises chlorinated polyethylene rubber, isoprene rubber and modified liquid fluororubber, and the modified liquid fluororubber is prepared by reacting carboxyl-terminated liquid fluororubber with an isocyanate-terminated epoxy prepolymer. The isocyanate-terminated epoxy prepolymer is prepared by reacting resorcinol diglycidyl ether, N-methylethanolamine and an isocyanate polymer, and the isocyanate polymer is prepared by polymerizing hexamethylene diisocyanate, so that the chemical corrosion resistance and high temperature resistance of the rubber are enhanced; and the composite modifier is prepared by reacting multi-element copolyether ester with fluorinated polybutadiene, so that the final rubber compound has excellent low-temperature brittleness resistance and long-term stability while keeping high strength.

Description

Technical Field

[0001] The present invention relates to the technical field of rubber, and specifically to a rubber compound for manufacturing medical seals and a preparation method thereof. Background Art

[0002] Medical industries use rubber seals, such as stoppers for disposable syringes, stoppers and caps for pre-filled syringes, bottle stoppers, etc., which belong to medical devices or pharmaceutical packaging materials. During use, they need to come into contact with drugs and have high requirements for their physical, chemical, and biological properties. Currently, the seals used in the domestic pharmaceutical industry are mainly made of chlorinated or brominated butyl rubber as raw materials, and rubber raw materials for manufacturing medical rubber seals using other rubber materials have not yet fully emerged. Through research on the composition, physical, chemical, and biological properties of rubber, it is found that chlorinated polyethylene rubber has extremely high similarity to chlorinated and brominated butyl rubber in terms of structure, physical properties, and processing properties. After blending and modification, technical indicators such as processing properties and physical properties can be comparable to those of chlorinated and brominated butyl rubber.

[0003] Fluororubber has good characteristics such as high temperature resistance, radiation resistance, solvent resistance, corrosion resistance, drug resistance, and strong oxidant resistance, as well as good physical properties, and is the best rubber type for seals, rubber hoses, and rubber gaskets, etc. As an important physical property, the strength and high temperature resistance of fluororubber play a decisive role in effective sealing. Therefore, the present invention prepares a rubber compound for manufacturing medical seals through the compounding of chlorinated polyethylene rubber and liquid fluororubber to solve the above problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a rubber compound for manufacturing medical seals and a preparation method thereof.

[0005] A technical solution proposed by the present invention to solve the above technical problem is: a rubber compound for manufacturing medical seals, comprising the following components in parts by weight: 100 - 160 parts of a rubber composition, 4 - 7 parts of a composite modifier, 10 - 20 parts of a reinforcing agent, 20 - 30 parts of a filler, 5 - 10 parts of a plasticizer, 2 - 4 parts of a vulcanizing agent, 2 - 4 parts of a crosslinking agent; the rubber composition is a chlorinated polyethylene rubber, isoprene rubber, and modified liquid fluororubber with a mass ratio of 50 - 80:20 - 50:30; the rubber compound for manufacturing medical seals is obtained by mixing the rubber composition, composite modifier, reinforcing agent, filler, plasticizer, vulcanizing agent, and crosslinking agent and then performing mixing and kneading.

[0006] Preferably, the modified liquid fluororubber is prepared by reacting a carboxyl-terminated liquid fluororubber with an isocyanate-terminated epoxy prepolymer, and the mass ratio of the carboxyl-terminated liquid fluororubber to the isocyanate-terminated epoxy prepolymer is 2-4:1; the isocyanate-terminated epoxy prepolymer is prepared by reacting resorcinol diglycidyl ether, N-methylethanolamine with an isocyanate polybody, and the mass ratio of resorcinol diglycidyl ether, N-methylethanolamine to the isocyanate polybody is 1:1:4.2-4.4; the isocyanate polybody is prepared by polymerizing hexamethylene diisocyanate.

[0007] Preferably, the composite modifier is prepared by reacting a polyether ester copolymer with fluorinated polybutadiene, and the mass ratio of the polyether ester copolymer to the fluorinated polybutadiene is 1:1-2; the polyether ester copolymer is prepared by introducing isophthalic acid and adipic acid during the synthesis of a thermoplastic polyether ester elastomer.

[0008] Preferably, the reinforcing agent is carbon black; the filler is one or a mixture of kaolin, white carbon black, and talc; the plasticizer is tributyl citrate; the vulcanizing agent is di-tert-butylperoxycumene; the crosslinking agent is benzoyl peroxide.

[0009] Preferably, the preparation method of the rubber compound for manufacturing a medical seal includes the following specific steps:

[0010] S1. Under a nitrogen atmosphere, mix resorcinol diglycidyl ether and N,N-dimethylacetamide in equal mass, stir evenly, then cool down to 8-10°C, and dropwise add an N,N-dimethylacetamide solution of N-methylethanolamine with a mass fraction of 40-60% at a rate of 1-3 ml / min. Add an isocyanate polybody that is 4.2-4.4 times the mass of resorcinol diglycidyl ether and N,N-dimethylacetamide that is 2-3 times the mass of resorcinol diglycidyl ether, heat up to 50-60°C, react for 5-8 h, and perform rotary evaporation to obtain the isocyanate-terminated epoxy prepolymer;

[0011] S2. Under a nitrogen atmosphere, mix the carboxyl-terminated liquid fluororubber, the isocyanate-terminated epoxy prepolymer, and the catalyst dibutyltin dilaurate in a mass ratio of 2-4:1:0.02-0.04, heat up to 90-110°C, react for 2-3 h, terminate the reaction with methanol and perform rotary evaporation to obtain the modified liquid fluororubber;

[0012] S3. Under a nitrogen atmosphere, mix the polyether ester copolymer, the fluorinated polybutadiene, and tetrahydrofuran in a mass ratio of 1:1-2:20, add the catalyst dibutyltin dilaurate that is 0.02-0.04 times the mass of the polyether ester copolymer, heat up to 100-120°C, react for 4-8 h, perform vacuum distillation and vacuum dry at 80-90°C to obtain the composite modifier;

[0013] S4. Mix chlorinated polyethylene rubber, isoprene rubber and modified liquid fluororubber in a mass ratio of 50 - 80:20 - 50:30 to obtain a rubber composition;

[0014] S5. Put the rubber composition into a mixer and stir for 15 - 30 min. Add a reinforcing agent and a filler. After mixing evenly, add a composite modifier, a plasticizer and a crosslinking agent, raise the temperature for rubber mixing. After rubber mixing, discharge the material, put it into an open mill to mix evenly, lower the roller, let it stand for 1.5 - 2.5 h and then transfer it to a filter press, filter it with a 150 - 300 - mesh filter screen, add a vulcanizing agent, mix evenly and then transfer it to a mold for molding to obtain a rubber compound for manufacturing medical seals.

[0015] Preferably, in the above step S1, the preparation method of the isocyanate poly - mer is as follows: Under a nitrogen atmosphere, mix toluene, hexamethylene diisocyanate, antioxidant tert - butylhydroquinone, polymerization inhibitor triphenyl phosphate and catalyst tetramethylammonium hydroxide in a mass ratio of 1:1.3 - 1.6:0.02 - 0.04:0.01:0.01 - 0.05, raise the temperature to 80 - 120 °C, react for 4 - 8 h, terminate the reaction with triphenyl phosphate, carry out vacuum distillation, dissolve it with acetone, filter, and distill again to obtain the isocyanate poly - mer.

[0016] Preferably, in the above step S2, the preparation method of the carboxyl - terminated liquid fluororubber is as follows: Under a nitrogen atmosphere, mix tetrafluoroethylene, maleic anhydride, benzoyl peroxide, perfluoroethane and dodecyl mercaptan in a mass ratio of 7 - 9:0.5 - 1:0.01 - 0.02:20:0.002 - 0.005, stir evenly and then raise the temperature to 60 - 80 °C, with a pressure of 1.8 - 3.0 Mpa, stir and react at 200 - 400 rpm for 6 - 8 h, cool to room temperature and terminate the reaction with hydroquinone, carry out vacuum distillation, disperse it in tetrahydrofuran, precipitate it with methanol and dry it in vacuum at 60 °C to obtain the carboxyl - terminated liquid fluororubber.

[0017] Preferably, in the above step S3, the preparation method of the multi - component copolyether ester is as follows: Under a nitrogen atmosphere, put terephthalic acid, isophthalic acid, adipic acid, 1,4 - butanediol, polytetrahydrofuran, tetrabutyl titanate, antioxidant 1010, anhydrous sodium phosphate in a reaction kettle in a mass ratio of 8 - 10:8 - 10:8 - 10:20:50 - 60:0.0003 - 0.004:0.06:0.001, raise the temperature to 225 - 235 °C, carry out an esterification reaction for 4 - 6 h, add tetrabutyl titanate in an amount of 0.02 - 0.04 times the mass of terephthalic acid, continue to raise the temperature to 245 - 255 °C, carry out a polycondensation reaction for 2 - 3 h, keep the pressure at 0.06 - 0.08 MPa by filling nitrogen and discharge and pelletize to obtain the multi - component copolyether ester.

[0018] Preferably, in the above step S3, the preparation method of fluorinated polybutadiene is as follows: under a nitrogen atmosphere, polybutadiene and tetrahydrofuran are mixed at a mass ratio of 1:10 - 12, and after stirring evenly, the temperature is lowered to -20 - -30°C, and a mixed gas of fluorine and nitrogen with a volume ratio of 1 - 3:10 is introduced at a rate of 0.5 - 0.8 L / min, and the reaction is carried out for 4 - 8 h, then precipitated and vacuum dried at 60 - 70°C to obtain fluorinated polybutadiene.

[0019] Preferably, in the above step S5, during rubber mixing, the temperature is raised to 120 - 140°C, kneaded for 30 - 60 min, and the vacuum degree is -0.06 - -0.1 Mpa.

[0020] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0021] The rubber compound for manufacturing medical seals prepared by the present invention is obtained by mixing and kneading a rubber composition and a composite modifier, etc.; the rubber composition includes chlorinated polyethylene rubber, isoprene rubber, and modified liquid fluororubber;

[0022] The modified liquid fluororubber is prepared by reacting a carboxyl - terminated liquid fluororubber with a terminal isocyanate - based epoxy prepolymer. The terminal isocyanate - based epoxy prepolymer is prepared by reacting resorcinol diglycidyl ether, N - methylethanolamine with an isocyanate polymer. The isocyanate polymer is prepared by polymerizing hexamethylene diisocyanate. After polymerization, hexamethylene diisocyanate forms a mixture containing isocyanurate - ring substances such as trimers, pentamers, and heptamers, and reacts with resorcinol diglycidyl ether and N - methylethanolamine to form a terminal isocyanate - based epoxy prepolymer. While reacting with the carboxyl - terminated liquid fluororubber, a modified liquid fluororubber with a cross - linked network structure is formed, which not only enhances the chemical corrosion resistance of the rubber, but also improves the high - temperature resistance after being blended with chlorinated polyethylene rubber and isoprene rubber, showing excellent sealing performance in the application of medical seals, and ensuring the reliability and safety of medical equipment.

[0023] The composite modifier is prepared by reacting a multi - component copolymerized ether ester with fluorinated polybutadiene. The multi - component copolymerized ether ester is prepared by introducing isophthalic acid and adipic acid during the synthesis of a thermoplastic polyether ester elastomer. The introduction of the composite modifier of isophthalic acid and fluorinated polybutadiene can not only form a homogeneous blend with the rubber composition, but also improve the mechanical properties of the rubber compound. The combination of the composite modifier and the modified liquid fluororubber, by optimizing the intermolecular interaction, enables the final rubber compound to have excellent high - temperature resistance and long - term high - temperature stability. Detailed implementation mode

[0024] The present invention will be specifically described below through embodiments. It is necessary to point out here that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention. Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those familiar to those skilled in the art.

[0025] In order to more clearly illustrate the method provided by the present invention, the following embodiments are used for detailed description. The test methods for each index of the rubber compound for manufacturing medical seals prepared in the embodiments and comparative examples are as follows:

[0026] The rubber compounds for manufacturing medical seals prepared in the embodiments and comparative examples are vulcanized at 170 °C and then tested for each index;

[0027] Cytotoxicity: The cytotoxicity test is carried out with reference to ISO 10993-5.

[0028] Mechanical properties: The tensile strength test is carried out with reference to ASTM D412.

[0029] Heat resistance: Heat aging treatment is carried out with reference to ASTM D573, and the change rate of tensile strength before and after heat aging is tested.

[0030] Chemical resistance: The test of volume change rate of chemical medium resistance is carried out with reference to ASTM D471.

[0031] Example 1

[0032] In this example, the mass parts of each component of the rubber compound for manufacturing medical seals are as follows:

[0033] 100 parts of rubber composition, 4 parts of composite modifier, 10 parts of reinforcing agent carbon black, 20 parts of filler kaolin, 5 parts of plasticizer tributyl citrate, 2 parts of vulcanizing agent di-tert-butyl peroxyisopropylbenzene, 2 parts of crosslinking agent benzoyl peroxide.

[0034] The preparation method of the rubber compound for manufacturing medical seals in this example is as follows:

[0035] S1. Under a nitrogen atmosphere, toluene, hexamethylene diisocyanate, antioxidant tert-butylhydroquinone, inhibitor triphenyl phosphate and catalyst tetramethylammonium hydroxide were mixed in a mass ratio of 1:1.3:0.02:0.01:0.01, heated to 80 °C, reacted for 4 h, terminated the reaction with triphenyl phosphate, distilled under reduced pressure, dissolved in acetone, filtered, and distilled again to obtain an isocyanate polyisomer; Under a nitrogen atmosphere, resorcinol diglycidyl ether and N,N-dimethylacetamide were mixed in equal mass, stirred evenly and then cooled to 8 °C, and a solution of N-methylacetamide in N,N-dimethylacetamide with a mass fraction of 40% was added dropwise at a rate of 1 ml / min. The isocyanate polyisomer 4.2 times the mass of resorcinol diglycidyl ether and N,N-dimethylacetamide 2 times the mass of resorcinol diglycidyl ether were added, heated to 50 °C, reacted for 5 h, and rotary evaporated to obtain a terminal isocyanate group epoxy prepolymer;

[0036] S2. The preparation method of the carboxyl-terminated liquid fluororubber is as follows: Under a nitrogen atmosphere, tetrafluoroethylene, maleic anhydride, benzoyl peroxide, perfluoroethane and dodecyl mercaptan were mixed in a mass ratio of 7:0.5:0.01:20:0.002, stirred evenly and then heated to 60 °C, the pressure was 1.8 Mpa, and the reaction was carried out at 200 rpm for 6 h, cooled to room temperature and terminated the reaction with hydroquinone, distilled under reduced pressure, dispersed in tetrahydrofuran, precipitated with methanol and dried in vacuum at 60 °C to obtain the carboxyl-terminated liquid fluororubber; Under a nitrogen atmosphere, the carboxyl-terminated liquid fluororubber, the terminal isocyanate group epoxy prepolymer and the catalyst dibutyltin dilaurate were mixed in a mass ratio of 2:1:0.02, heated to 90 °C, reacted for 2 h, terminated the reaction with methanol and rotary evaporated to obtain the modified liquid fluororubber;

[0037] S3. Under a nitrogen atmosphere, terephthalic acid, isophthalic acid, adipic acid, 1,4-butanediol, polytetrahydrofuran, tetrabutyl titanate, antioxidant 1010, and anhydrous sodium phosphate were mixed in a mass ratio of 8:8:8:20:50:0.00034:0.06:0.001 and placed in a reaction kettle. The temperature was raised to 225°C, and an esterification reaction was carried out for 4 h. Then, tetrabutyl titanate with a mass 0.02 times that of terephthalic acid was added, and the temperature was further raised to 245°C for a polycondensation reaction for 2.5 h. Nitrogen was filled to maintain a pressure of 0.06 MPa for discharging and pelletizing, obtaining a multi-component copolymerized ether ester; Under a nitrogen atmosphere, polybutadiene and tetrahydrofuran were mixed in a mass ratio of 1:10, stirred evenly, and then cooled to -20°C. A mixed gas of fluorine and nitrogen with a volume ratio of 1:10 was introduced at a rate of 0.5 L / min for a reaction of 4 h, followed by precipitation and vacuum drying at 600°C to obtain fluorinated polybutadiene; Under a nitrogen atmosphere, the multi-component copolymerized ether ester, fluorinated polybutadiene, and tetrahydrofuran were mixed in a mass ratio of 1:1:20, and dibutyltin dilaurate, a catalyst with a mass 0.02 times that of the multi-component copolymerized ether ester, was added. The temperature was raised to 100°C, and the reaction was carried out for 4 - 8 h. Then, vacuum distillation was performed and vacuum drying was carried out at 80°C to obtain a composite modifier;

[0038] S4. Chlorinated polyethylene rubber, isoprene rubber, and modified liquid fluororubber were mixed in a mass ratio of 50:20:30 to obtain a rubber composition;

[0039] S5. The rubber composition was put into a mixer and stirred for 15 min. Then, a reinforcing agent and a filler were added. After mixing evenly, the composite modifier, a plasticizer, and a cross-linking agent were added, and the rubber was kneaded with temperature increase. During the rubber kneading, the temperature was raised to 120°C, and kneading was carried out for 30 min with a vacuum degree of -0.06 Mpa. After discharging after rubber kneading, it was put into an open mill for uniform mixing, and then taken off the lower roller. After standing for 1.5 h, it was transferred to a filter and filtered with a 150-mesh filter screen. Then, a vulcanizing agent was added, and after mixing evenly, it was transferred to a mold for molding to obtain a rubber compound for manufacturing medical seals.

[0040] Example 2

[0041] In this example, the mass fractions of the components of the rubber compound for manufacturing medical seals are as follows:

[0042] 130 parts of the rubber composition, 6 parts of the composite modifier, 15 parts of the reinforcing agent carbon black, 25 parts of the filler silica, 8 parts of the plasticizer tributyl citrate, 3 parts of the vulcanizing agent di-tert-butyl peroxide isopropylbenzene, and 3 parts of the cross-linking agent benzoyl peroxide.

[0043] In this example, the preparation method of the rubber compound for manufacturing medical seals is as follows:

[0044] S1. Under a nitrogen atmosphere, toluene, hexamethylene diisocyanate, antioxidant tert-butylhydroquinone, polymerization inhibitor triphenyl phosphate, and catalyst tetramethylammonium hydroxide were mixed in a mass ratio of 1:1.5:0.03:0.01:0.03, heated to 100 °C, reacted for 6 h, terminated the reaction with triphenyl phosphate, distilled under reduced pressure, dissolved in acetone, filtered, and distilled again to obtain an isocyanate polyisomer; Under a nitrogen atmosphere, resorcinol diglycidyl ether and N,N-dimethylacetamide were mixed in equal mass, stirred evenly and then cooled to 9 °C, and a 50% mass fraction solution of N-methylacetamide in N,N-dimethylacetamide was added dropwise at a rate of 2 ml / min. Add an isocyanate polyisomer 4.3 times the mass of resorcinol diglycidyl ether and N,N-dimethylacetamide 2.5 times the mass of resorcinol diglycidyl ether, heat to 55 °C, react for 6 h, and perform rotary evaporation to obtain a terminal isocyanate group epoxy prepolymer;

[0045] S2. The preparation method of the carboxyl-terminated liquid fluororubber is as follows: Under a nitrogen atmosphere, tetrafluoroethylene, maleic anhydride, benzoyl peroxide, perfluoroethane, and dodecyl mercaptan were mixed in a mass ratio of 8:0.8:0.015:20:0.004, stirred evenly and then heated to 70 °C, the pressure was 2.6 Mpa, and the reaction was carried out with stirring at 300 rpm for 7 h, cooled to room temperature and terminated the reaction with hydroquinone, distilled under reduced pressure, dispersed in tetrahydrofuran, precipitated with methanol and dried in vacuum at 60 °C to obtain the carboxyl-terminated liquid fluororubber; Under a nitrogen atmosphere, the carboxyl-terminated liquid fluororubber, the terminal isocyanate group epoxy prepolymer, and the catalyst dibutyltin dilaurate were mixed in a mass ratio of 3:1:0.03, heated to 100 °C, reacted for 2.5 h, terminated the reaction with methanol and performed rotary evaporation to obtain the modified liquid fluororubber;

[0046] S3. Under a nitrogen atmosphere, terephthalic acid, isophthalic acid, adipic acid, 1,4-butanediol, polytetrahydrofuran, tetrabutyl titanate, antioxidant 1010, and anhydrous sodium phosphate were mixed in a mass ratio of 9:9:9:20:55:0.00035:0.06:0.001 and placed in a reaction kettle. The temperature was raised to 230 °C, and an esterification reaction was carried out for 5 h. Then, tetrabutyl titanate with a mass 0.03 times that of terephthalic acid was added, and the temperature was further raised to 250 °C for a polycondensation reaction for 2.5 h. Nitrogen was filled to maintain a pressure of 0.07 MPa, and then the product was discharged and pelletized to obtain a polyether ester copolymer. Under a nitrogen atmosphere, polybutadiene and tetrahydrofuran were mixed in a mass ratio of 1:11, and after being stirred evenly, the temperature was lowered to -25 °C. A mixed gas of fluorine and nitrogen with a volume ratio of 2:10 was introduced at a rate of 0.7 L / min for a reaction of 6 h. The product was precipitated and vacuum-dried at 65 °C to obtain fluorinated polybutadiene. Under a nitrogen atmosphere, the polyether ester copolymer, fluorinated polybutadiene, and tetrahydrofuran were mixed in a mass ratio of 1:1.5:20, and dibutyltin dilaurate, a catalyst with a mass 0.03 times that of the polyether ester copolymer, was added. The temperature was raised to 110 °C for a reaction of 6 h, followed by vacuum distillation and vacuum drying at 85 °C to obtain a composite modifier.

[0047] S4. Chlorinated polyethylene rubber, isoprene rubber, and modified liquid fluororubber were mixed in a mass ratio of 70:35:15 to obtain a rubber composition.

[0048] S5. The rubber composition was put into a mixer and stirred for 22 min. Then, a reinforcing agent and a filler were added. After mixing evenly, a composite modifier, a plasticizer, and a crosslinking agent were added, and the rubber was kneaded while heating. During the rubber kneading, the temperature was raised to 130 °C, and kneading was carried out for 45 min with a vacuum degree of -0.08 Mpa. After the rubber kneading, the product was discharged, put into an open mill for uniform mixing, and the lower roller was used. After standing for 2 h, it was transferred to a filter and filtered with a 200-mesh filter screen. Then, a vulcanizing agent was added, and after mixing evenly, it was transferred to a mold for molding to obtain a rubber masterbatch for manufacturing medical seals.

[0049] Example 3

[0050] In this example, the mass parts of each component of the rubber masterbatch for manufacturing medical seals were as follows:

[0051] 160 parts of the rubber composition, 7 parts of the composite modifier, 20 parts of the reinforcing agent carbon black, 30 parts of the filler talcum powder, 10 parts of the plasticizer tributyl citrate, 4 parts of the vulcanizing agent di-tert-butyl peroxide isopropylbenzene, and 4 parts of the crosslinking agent benzoyl peroxide.

[0052] In this example, the preparation method of the rubber masterbatch for manufacturing medical seals was as follows:

[0053] S1. Under a nitrogen atmosphere, toluene, hexamethylene diisocyanate, antioxidant tert-butylhydroquinone, polymerization inhibitor triphenyl phosphate, and catalyst tetramethylammonium hydroxide were mixed in a mass ratio of 1:1.6:0.04:0.01:0.05, heated to 120 °C, reacted for 8 h, terminated the reaction with triphenyl phosphate, distilled under reduced pressure, dissolved in acetone, filtered, and distilled again to obtain an isocyanate polyisomer; under a nitrogen atmosphere, resorcinol diglycidyl ether and N,N-dimethylacetamide were mixed in equal mass, stirred evenly and cooled to 10 °C, and a solution of N-methylacetamide in N,N-dimethylacetamide with a mass fraction of 60% was added dropwise at a rate of 3 ml / min, and an isocyanate polyisomer 4.4 times the mass of resorcinol diglycidyl ether and N,N-dimethylacetamide 3 times the mass of resorcinol diglycidyl ether were added, heated to 60 °C, reacted for 8 h, and rotary evaporated to obtain a terminal isocyanate group epoxy prepolymer;

[0054] S2. The preparation method of the carboxyl-terminated liquid fluororubber is as follows: Under a nitrogen atmosphere, tetrafluoroethylene, maleic anhydride, benzoyl peroxide, perfluoroethane, and dodecyl mercaptan were mixed in a mass ratio of 9:1:0.02:20:0.005, stirred evenly and heated to 80 °C, the pressure was 3.0 Mpa, stirred and reacted at 400 rpm for 8 h, cooled to room temperature and terminated the reaction with hydroquinone, distilled under reduced pressure, dispersed in tetrahydrofuran, precipitated with methanol and dried in vacuum at 60 °C to obtain the carboxyl-terminated liquid fluororubber; under a nitrogen atmosphere, the carboxyl-terminated liquid fluororubber, the terminal isocyanate group epoxy prepolymer, and the catalyst dibutyltin dilaurate were mixed in a mass ratio of 4:1:0.04, heated to 110 °C, reacted for 3 h, terminated the reaction with methanol and rotary evaporated to obtain the modified liquid fluororubber;

[0055] S3. Under a nitrogen atmosphere, terephthalic acid, isophthalic acid, adipic acid, 1,4-butanediol, polytetrahydrofuran, tetrabutyl titanate, antioxidant 1010, and anhydrous sodium phosphate were mixed in a mass ratio of 10:10:10:20:60:0.004:0.06:0.001 and placed in a reaction kettle. The temperature was raised to 235°C, and an esterification reaction was carried out for 6 h. Then, tetrabutyl titanate with a mass 0.02 - 0.04 times that of terephthalic acid was added, and the temperature was further raised to 255°C for a polycondensation reaction for 3 h. Nitrogen was filled to maintain the pressure at 0.06 - 0.08 MPa, and then the product was discharged and pelletized to obtain a polyaryletherester copolymer; Under a nitrogen atmosphere, polybutadiene and tetrahydrofuran were mixed in a mass ratio of 1:12. After stirring evenly, the temperature was lowered to -30°C, and a mixed gas of fluorine and nitrogen with a volume ratio of 3:10 was introduced at a rate of 0.8 L / min for a reaction of 8 h. The product was precipitated and vacuum dried at 70°C to obtain fluorinated polybutadiene; Under a nitrogen atmosphere, the polyaryletherester copolymer, fluorinated polybutadiene, and tetrahydrofuran were mixed in a mass ratio of 1:2:20. Dibutyltin dilaurate, a catalyst with a mass 0.04 times that of the polyaryletherester copolymer, was added, and the temperature was raised to 120°C for a reaction of 8 h. Then, it was subjected to vacuum distillation and vacuum dried at 90°C to obtain a composite modifier;

[0056] S4. Chlorinated polyethylene rubber, isoprene rubber, and modified liquid fluororubber were mixed in a mass ratio of 80:50:30 to obtain a rubber composition;

[0057] S5. The rubber composition was put into a mixer and stirred for 30 min. Then, a reinforcing agent and a filler were added. After mixing evenly, a composite modifier, a plasticizer, and a crosslinking agent were added, and the rubber was kneaded with the temperature raised. During the rubber kneading, the temperature was raised to 140°C, and it was kneaded for 60 min with a vacuum degree of -0.1 Mpa. After the rubber kneading, the product was discharged, put into an open mill for uniform mixing, and then taken off the lower roller. After standing for 2.5 h, it was transferred to a filter and filtered with a 300-mesh filter screen. Then, a vulcanizing agent was added, and after mixing evenly, it was transferred to a mold for molding to obtain a rubber compound for manufacturing medical seals.

[0058] Comparative Example 1

[0059] The preparation method of Comparative Example 1 was the same as that of Example 2. The difference between the rubber compound for manufacturing medical seals in this example and that in Example 2 was that the modified liquid fluororubber was only carboxyl-terminated liquid fluororubber.

[0060] Comparative Example 2

[0061] The preparation method of Comparative Example 2 was the same as that of Example 2. The difference between the rubber compound for manufacturing medical seals in this example and that in Example 2 was that the modified liquid fluororubber was prepared by reacting carboxyl-terminated liquid fluororubber with an isocyanate polymer.

[0062] Comparative Example 3

[0063] The preparation method of Comparative Example 3 is the same as that of Example 2. The difference between the rubber compound for manufacturing medical seals and that of Example 2 is that the composite modifier is only polyether ester copolymer.

[0064] Comparative Example 4

[0065] The preparation method of Comparative Example 4 is the same as that of Example 2. The difference between the rubber compound for manufacturing medical seals and that of Example 2 is that the composite modifier is only fluorinated polybutadiene.

[0066] Effect Example

[0067] The following Table 1 shows the performance test results of the rubber compounds for manufacturing medical seals prepared in the examples and comparative examples;

[0068] Table 1

[0069]

[0070] From the comparison of the performance data in Table 1, it can be seen that the rubber compound for manufacturing medical seals prepared by the present invention not only has excellent toughness and high temperature resistance, but also has long-term high temperature stability;

[0071] From the comparison of the experimental data of Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2, it can be found that hexamethylene diisocyanate forms a mixture of substances containing isocyanurate rings such as trimers, pentamers and heptamers after polymerization, reacts with resorcinol diglycidyl ether and N-methylethanolamine to form a terminal isocyanate group epoxy prepolymer, and reacts with terminal carboxyl liquid fluororubber to form a modified liquid fluororubber with a crosslinked network structure at the same time. This not only enhances the chemical corrosion resistance of the rubber, but also improves the high temperature resistance after blending with chlorinated polyethylene rubber and isoprene rubber, showing excellent sealing performance in the application of medical seals and ensuring the reliability and safety of medical equipment.

[0072] From the comparison of the experimental data of Example 1, Example 2, Example 3 and Comparative Example 3, Comparative Example 4, it can be found that the introduction of the composite modifier of isophthalic acid and fluorinated polybutadiene can not only form a homogeneous blend with the modified liquid fluororubber, but also improve the mechanical properties of the rubber compound. The combination of the composite modifier and the modified liquid fluororubber optimizes the intermolecular interaction, making the final rubber compound have excellent high temperature resistance and long-term high temperature stability.

[0073] Obviously, the above embodiments are merely examples given to clearly illustrate the embodiments of the present invention, rather than limitations on the embodiments of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the embodiments here. And these obvious changes or modifications derived from the spirit of the present invention still fall within the protection scope of the present invention.

Claims

1. A rubber compound for manufacturing medical seals, characterized in that, Comprising the following components in parts by weight: 100 to 160 parts of a rubber composition, 4 to 7 parts of a composite modifier, 10 to 20 parts of a reinforcing agent, 20 to 30 parts of a filler, 5 to 10 parts of a plasticizer, 2 to 4 parts of a vulcanizing agent, 2 to 4 parts of a crosslinking agent; the rubber composition is a chlorinated polyethylene rubber, isoprene rubber, and modified liquid fluororubber in a mass ratio of 50 to 80:20 to 50:30; The rubber masterbatch for manufacturing medical seals is obtained by mixing the rubber composition, composite modifier, reinforcing agent, filler, plasticizer, vulcanizing agent, and crosslinking agent and then performing kneading.

2. The rubber compound for manufacturing a medical seal according to claim 1, wherein The modified liquid fluororubber is prepared by reacting a carboxyl-terminated liquid fluororubber with an isocyanate-terminated epoxy prepolymer, and the mass ratio of the carboxyl-terminated liquid fluororubber to the isocyanate-terminated epoxy prepolymer is 2 to 4:1; the isocyanate-terminated epoxy prepolymer is prepared by reacting resorcinol diglycidyl ether, N-methylethanolamine, and an isocyanate polymer, and the mass ratio of resorcinol diglycidyl ether, N-methylethanolamine, and the isocyanate polymer is 1:1:4.2 to 4.4; the isocyanate polymer is prepared by polymerizing hexamethylene diisocyanate.

3. A rubber compound for manufacturing a medical seal according to claim 1, characterized in that, The composite modifier is prepared by reacting a polyether ester copolymer with fluorinated polybutadiene, and the mass ratio of the polyether ester copolymer to fluorinated polybutadiene is 1:1 to 2; the polyether ester copolymer is prepared by introducing isophthalic acid and adipic acid during the synthesis of a thermoplastic polyether ester elastomer.

4. A rubber compound for manufacturing a medical seal according to claim 1, characterized in that, The reinforcing agent is carbon black; the filler is one or a mixture of kaolin, silica, and talc; the plasticizer is tributyl citrate; the vulcanizing agent is di-tert-butylperoxycumene; the crosslinking agent is benzoyl peroxide.

5. The preparation method of a rubber compound for manufacturing a medical seal according to claim 1, wherein, Including the following specific steps: S1. Under a nitrogen atmosphere, mix resorcinol diglycidyl ether and N,N-dimethylacetamide in equal mass, stir evenly, then cool to 8 to 10 °C, and dropwise add an N,N-dimethylacetamide solution of N-methylethanolamine with a mass fraction of 40 to 60% at a rate of 1 to 3 ml / min. Add an isocyanate polymer 4.2 to 4.4 times the mass of resorcinol diglycidyl ether and N,N-dimethylacetamide 2 to 3 times the mass of resorcinol diglycidyl ether, heat to 50 to 60 °C, react for 5 to 8 h, and perform rotary evaporation to obtain the isocyanate-terminated epoxy prepolymer; S2. Under a nitrogen atmosphere, mix the carboxyl-terminated liquid fluororubber, isocyanate-terminated epoxy prepolymer, and the catalyst dibutyltin dilaurate in a mass ratio of 2 to 4:1:0.02 to 0.04, heat to 90 to 110 °C, react for 2 to 3 h, terminate the reaction with methanol and perform rotary evaporation to obtain the modified liquid fluororubber; S3. Under a nitrogen atmosphere, mix the polyether ester copolymer, fluorinated polybutadiene, and tetrahydrofuran in a mass ratio of 1:1 to 2:20, add the catalyst dibutyltin dilaurate 0.02 to 0.04 times the mass of the polyether ester copolymer, heat to 100 to 120 °C, react for 4 to 8 h, perform vacuum distillation and vacuum dry at 80 to 90 °C to obtain the composite modifier; S4. Mix chlorinated polyethylene rubber, isoprene rubber and modified liquid fluororubber in a mass ratio of 50 - 80:20 - 50:30 to obtain a rubber composition; S5. Put the rubber composition into a kneader and stir for 15 - 30 min, then add a reinforcing agent and a filler. After mixing evenly, add a composite modifier, a plasticizer and a crosslinking agent, raise the temperature for rubber mixing, discharge the material after rubber mixing, put it into an open mill for uniform mixing, lower the roller, let it stand for 1.5 - 2.5 h and then transfer it to a filter, filter it with a 150 - 300 - mesh filter screen, add a vulcanizing agent, mix evenly and then transfer it to a mold for molding to obtain a rubber compound for manufacturing medical seals.

6. The preparation method of a rubber compound for manufacturing a medical seal according to claim 5, characterized in that, In the above step S1, the preparation method of the isocyanate polybody is as follows: Under a nitrogen atmosphere, mix toluene, hexamethylene diisocyanate, antioxidant tert - butylhydroquinone, inhibitor triphenyl phosphate and catalyst tetramethylammonium hydroxide in a mass ratio of 1:1.3 - 1.6:0.02 - 0.04:0.01:0.01 - 0.05, raise the temperature to 80 - 120 °C, react for 4 - 8 h, terminate the reaction with triphenyl phosphate, carry out vacuum distillation, dissolve with acetone, filter, and distill again to obtain the isocyanate polybody.

7. The preparation method of a rubber compound for manufacturing a medical seal according to claim 5, characterized in that, In the above step S2, the preparation method of the carboxyl - terminated liquid fluororubber is as follows: Under a nitrogen atmosphere, mix tetrafluoroethylene, maleic anhydride, benzoyl peroxide, perfluoroethane and dodecyl mercaptan in a mass ratio of 7 - 9:0.5 - 1:0.01 - 0.02:20:0.002 - 0.005, stir evenly and then raise the temperature to 60 - 80 °C, the pressure is 1.8 - 3.0 Mpa, stir and react at 200 - 400 rpm for 6 - 8 h, cool to room temperature and terminate the reaction with hydroquinone, carry out vacuum distillation, disperse in tetrahydrofuran, precipitate with methanol and dry in vacuum at 60 °C to obtain the carboxyl - terminated liquid fluororubber.

8. The preparation method of a rubber compound for manufacturing a medical seal according to claim 5, characterized in that, In the above step S3, the preparation method of the polyether - ester copolymer is as follows: Under a nitrogen atmosphere, put terephthalic acid, isophthalic acid, adipic acid, 1,4 - butanediol, polytetrahydrofuran, tetrabutyl titanate, antioxidant 1010, anhydrous sodium phosphate in a mass ratio of 8 - 10:8 - 10:8 - 10:20:50 - 60:0.0003 - 0.004:0.06:0.001 into a reaction kettle, raise the temperature to 225 - 235 °C, carry out an esterification reaction for 4 - 6 h, add tetrabutyl titanate in an amount 0.02 - 0.04 times the mass of terephthalic acid, continue to raise the temperature to 245 - 255 °C, carry out a polycondensation reaction for 2 - 3 h, discharge and pelletize while filling nitrogen to keep the pressure at 0.06 - 0.08 MPa to obtain the polyether - ester copolymer.

9. The preparation method of a rubber compound for manufacturing a medical seal according to claim 5, characterized in that, In the above step S3, the preparation method of fluorinated polybutadiene is as follows: Under a nitrogen atmosphere, mix polybutadiene and tetrahydrofuran in a mass ratio of 1:10 - 12, stir evenly, then cool to - 20 - 30 °C, and introduce a mixed gas of fluorine and nitrogen with a volume ratio of 1 - 3:10 at a rate of 0.5 - 0.8 L / min, react for 4 - 8 h, precipitate and dry in vacuum at 60 - 70 °C to obtain fluorinated polybutadiene.

10. The preparation method of a rubber compound for manufacturing a medical seal according to claim 5, characterized in that, In the above step S5, during rubber mixing, the temperature is raised to 120-140°C, kneading is carried out for 30-60 minutes, and the vacuum degree is -0.06 to -0.1 Mpa.

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