Brominated butyl rubber piston for pre-filled syringe and preparation method of brominated butyl rubber piston

Abstract

The invention provides a brominated butyl rubber piston for a pre-filled syringe and a preparation method of the brominated butyl rubber piston, and relates to the technical field of rubber pistons. The brominated butyl rubber piston comprises a basic elastomer and an inert barrier film covering the surface of the basic elastomer. The basic elastomer comprises brominated butyl rubber, bio-based rubber, polyisobutene, talcum powder, calcined kaolin, carbon black, magnesium powder, titanium dioxide, sulfur, active magnesium oxide, polytetrafluoroethylene wax and a slip agent; the inert barrier membrane is polytetrafluoroethylene modified by modified polydimethylsiloxane. The pharmaceutical composition has good drug compatibility and administration convenience, and ensures the safety of medication.

Description

Technical Field

[0001] The invention relates to the technical field of rubber pistons, and in particular to a brominated butyl rubber piston for a prefilled syringe and a preparation method thereof. Background Art

[0002] In recent years, prefilled syringes have been used more and more widely. They can directly fill the liquid medicine into the syringe, and can be directly injected when used. The operation is very simple and can effectively prevent the liquid medicine from being contaminated or misused. As a multifunctional seal in direct contact with the liquid medicine in the prefilled syringe, the performance of the rubber stopper directly affects the safety and effectiveness of the drug during storage and use.

[0003] At present, the rubber plugs in the medical field are mainly brominated butyl rubber (BI IR) rubber plugs. Although it has excellent intrinsic cleanliness, chemical stability, air tightness and biological performance, it is affected by the complex components in the rubber plugs and the concentration gradient of the raw materials. When the BI IR rubber plugs come into contact with some drugs with strong molecular activity, they may interact with the drugs and cause compatibility problems. In the prior art, a layer of inert coating material with certain adhesion and flexibility is coated on the surface of the rubber plug, such as polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, perfluoroalkoxyethylene, etc., which prevents the direct contact between the rubber plug and the drug, and the active substances in the rubber plug are blocked by the inert coating material, and will not contaminate the drug during the drug sealing process. However, the above-mentioned inert coating material has low surface energy, fewer reactive sites, weak bonding with the rubber piston surface, and there is a risk of falling off and slipping during use. Summary of the invention

[0004] The purpose of the present invention is to provide a brominated butyl rubber piston for a prefilled syringe, which has good drug compatibility and drug administration convenience, and ensures the safety of drug administration.

[0005] Another object of the present invention is to provide a method for preparing a brominated butyl rubber piston for a prefilled syringe, which can make the rubber piston have good texture and elasticity, and can effectively seal the drug solution during the injection process to avoid leakage and contamination of the drug solution.

[0006] The present invention is achieved through the following technical solutions:

[0007] A brominated butyl rubber piston for a prefilled syringe comprises a base elastomer and an inert barrier film covering the surface of the base elastomer; the base elastomer comprises, by weight, 80-120 parts of brominated butyl rubber, 10-20 parts of bio-based rubber, 0.5-3 parts of polyisobutylene, 10-20 parts of talc, 20-30 parts of calcined kaolin, 3-7 parts of carbon black, 10-20 parts of magnesium powder, 1-3 parts of titanium dioxide, 0.3-2 parts of sulfur, 3-8 parts of active magnesium oxide, 1-3 parts of polytetrafluoroethylene wax and 5-10 parts of a lubricant; the inert barrier film is polytetrafluoroethylene modified with modified polydimethylsiloxane.

[0008] A method for preparing a brominated butyl rubber piston for a prefilled syringe comprises the following steps:

[0009] A. Rubber refining: the bio-based rubber, part of the brominated butyl rubber and carbon black are subjected to a first-stage internal refining, the remaining brominated butyl rubber, active magnesium oxide and white carbon black are added for a second-stage internal refining, magnesium powder, titanium dioxide and talcum powder are added for a third-stage internal refining, and finally the remaining raw materials except sulfur are added for a fourth-stage internal refining; after cooling, sulfur is added for open refining to obtain a rubber sheet;

[0010] B. Preforming: calendaring, vulcanizing, punching and cleaning the film to obtain a prefabricated rubber piston;

[0011] C. Spraying and curing: spray inert barrier material on the surface of prefabricated rubber piston, dry and cure, and obtain the finished bromobutyl rubber piston.

[0012] The technical solution of the present invention has at least the following advantages and beneficial effects:

[0013] In the present invention, polydimethylsiloxane is first modified once, and a large number of Si-OC bonds are converted into Si-O-Si bonds by reacting γ-methacryloxypropyltrimethoxysilane with polydimethylsiloxane, and acryloyloxy groups are generated at the same time. During the thermal curing process, the molecular volume of the Si-O-Si bond is large and the cohesive energy density is low, so that the inert barrier film has good high and low temperature resistance, hydrophobicity, air permeability and weather resistance, which helps to extend the service life of the coating; the acryloyloxy group can improve the weather resistance and waterproof performance of the coating, and at the same time, the coating exhibits good adhesion, mechanical properties and thermal stability during the curing process, and improves the bonding strength between the coating and the base elastomer. Then, methacrylate functional monomers are used to perform secondary modification on polydimethylsiloxane. Under the action of a photoinitiator, the double bonds in the methacrylate functional monomers are opened to form acrylate free radicals, and the silicon oxygen bonds in the polydimethylsiloxane are opened to form silicon oxygen free radicals. These free radicals are combined with each other to form long-chain polymers, and the long-chain polymers are interlaced to form a three-dimensional network structure. The modified polydimethylsiloxane has good solubility, interfacial activity, biocompatibility, corrosion resistance and low viscosity.

[0014] Modifying polytetrafluoroethylene with modified polydimethylsiloxane and coating the modified polydimethylsiloxane on the surface of polytetrafluoroethylene can, on the one hand, increase the surface energy of polytetrafluoroethylene and make the degree of bonding between polytetrafluoroethylene and the base elastomer better; on the other hand, a double-layer membrane structure with polydimethylsiloxane membrane and polytetrafluoroethylene membrane can be formed to improve the barrier performance of the inert barrier membrane. The above-mentioned inert barrier membrane can reduce the overall particle level, prevent the drug from being contaminated by the extract, and ensure that the surface of the packaging material has good compatibility with the drug.

[0015] Bio-based materials can interact with microorganisms in the environment to achieve the purpose of natural degradation. They can replace traditional rubber materials made of oil or natural gas, and can effectively reduce environmental pollution. Polyisobutylene can increase the strength and hardness of the product, prevent the generation of particles during subsequent processing, and improve the sealing of the product. Magnesium powder can make the rubber have a smooth surface after calendering, prevent the rubber from generating bubbles, and facilitate subsequent processing. Polytetrafluoroethylene wax has no obvious damage to the elastic behavior of rubber. While improving the physical properties of rubber, it will not affect the performance of rubber products, thereby ensuring the durability and reliability of rubber products, improving the sliding properties of products, and ensuring the safe packaging and transportation of medicines. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0017] A brominated butyl rubber piston for a prefilled syringe comprises a base elastomer and an inert barrier film covering the surface of the base elastomer; the base elastomer comprises, by weight, 80-120 parts of brominated butyl rubber, 10-20 parts of bio-based rubber, 0.5-3 parts of polyisobutylene, 10-20 parts of talc, 20-30 parts of calcined kaolin, 3-7 parts of carbon black, 10-20 parts of magnesium powder, 1-3 parts of titanium dioxide, 0.3-2 parts of sulfur, 3-8 parts of active magnesium oxide, 1-3 parts of polytetrafluoroethylene wax and 5-10 parts of a lubricant; the inert barrier film is polytetrafluoroethylene modified with modified polydimethylsiloxane.

[0018] Furthermore, the bio-based rubber is one or more of eucommia rubber, polylactic acid rubber and polyhydroxyalkanoate rubber. Eucommia rubber is preferred, which is a natural polymer material with inherent biocompatibility, environmental friendliness and degradable properties. However, eucommia rubber has low flexibility, small deformation and low elasticity, and brominated butyl rubber has poor degradability. Eucommia rubber and brominated butyl rubber are mixed and kneaded, and the two are blended and modified, so that the material has excellent biocompatibility, degradability and processing performance, and reduces production costs.

[0019] Furthermore, the carbon black includes 1-3 parts of white carbon black and 2-4 parts of black carbon black by weight. The surface of white carbon black contains a large number of hydroxyl groups, which can react chemically with double bonds in synthetic polymers to form chemical bonds. This reaction can significantly improve the dispersibility and reinforcing effect of white carbon black in the rubber compound. Silane coupling agents can also be used to modify the surface of white carbon black, significantly improving its compatibility with rubber, and improving dispersibility and reinforcing effect. Black carbon black can improve the wear resistance, oxidation resistance and weather resistance of the rubber plug, and can also be used as a filler to reduce the cost of rubber products.

[0020] Furthermore, the lubricant is a fluorine-free lubricant. Preferably, SS4028 is a fluorine-free lubricant. Because the brominated butyl rubber piston has a large sliding friction resistance with the syringe when used in a polymer prefilled syringe. Using a fluorine-free lubricant to replace the traditional fluorine additive can reduce the friction coefficient of the rubber piston, improve the smoothness, and reduce wear; combined with the excellent lubricity and non-stickiness of polytetrafluoroethylene wax, the friction and adhesion of the rubber plug during use can be further reduced; at the same time, polytetrafluoroethylene wax and magnesium powder can improve the surface finish of the rubber plug during preforming, and through the triple effect, the sliding property of the rubber piston is improved, the friction resistance of the rubber piston is improved, and the drug administration operation is convenient.

[0021] Active magnesium oxide is used as a vulcanization accelerator. Its active oxygen atoms can react with sulfur atoms in the vulcanizer to form sulfur-oxygen bonds, thereby accelerating the vulcanization reaction. In addition, the acid absorption function of active magnesium oxide effectively neutralizes the acidic substances produced during the production process, protects the internal structure of the rubber plug, improves the fluidity of the rubber, and makes the rubber plug more uniform during the molding process and less susceptible to the external environment. Among them, magnesium oxide can be processed: 1) Surface modification: Surface modification of magnesium hydroxide using a silane coupling agent can improve its dispersibility and compatibility in polymers. 2) Modification treatment: a. Doping modification: By doping a small amount of rare earth elements such as cerium and lanthanum, the catalytic performance of magnesium oxide can be significantly improved; b. Composite modification: Compounding magnesium oxide with polymer materials such as polypropylene, epoxy resin, etc. can significantly improve the mechanical properties and thermal stability of magnesium oxide. Through the above processing, the dispersibility of magnesium oxide in the rubber can be improved, the vulcanization reaction process can be accelerated, and the compatibility, mechanical properties and thermal stability of the rubber piston can be improved.

[0022] Magnesium powder can significantly improve the mechanical strength and wear resistance of rubber products. By evenly mixing it into plasticized rubber, magnesium powder can interact with rubber molecular chains to form a strong network structure, thereby improving the overall strength and wear resistance of rubber products. During the rubber mixing process, the uniform distribution of magnesium powder helps to improve the fluidity of the rubber, making the mixing process smoother, reducing energy consumption and improving production efficiency. This efficient mixing process not only reduces production time, but also helps to maintain the quality stability of rubber products between batches. Magnesium powder can improve the performance of rubber in processes such as calendering and extrusion, and speed up processing rates. Replacing some expensive raw materials with magnesium powder can reduce production costs and improve efficiency. Magnesium powder contains aromatic compounds that can prevent polymers from being damaged by heat, light or oxygen, and maintain the strength and toughness of the rubber. Magnesium powder can enhance the tensile strength, impact strength, shear strength, anti-interference bending and hardness of the rubber, while reducing deformation and elongation, and reducing the thermal expansion coefficient.

[0023] Sulfur can promote the vulcanization process of rubber. During the vulcanization process, sulfur reacts with double bonds in rubber to form vulcanized rubber, thereby transforming the rubber molecules from a linear structure to a network structure, improving the elasticity and heat resistance of the rubber. The vulcanization system composed of sulfur and active magnesium oxide can not only speed up the vulcanization speed, but also adjust the ratio of the two to improve the absorbance of the product.

[0024] The heavy metal content in calcined kaolin is very low, which can ensure that the piston has good biosafety and drug stability, and does not affect human health and drug safety. Talc is a type of magnesium silicate with a special layered structure. Its unique layered structure reduces its permeability to liquids or gases, and its lamellar structure can reduce the diffusion rate of chemicals into the rubber. Choosing calcined kaolin and talcum powder as fillers can reduce the compression permanent deformation of the piston, and to a certain extent improve the service life and performance of medical sealing materials.

[0025] Further, the modification method of the modified polydimethylsiloxane includes: 1) using γ-methacryloxypropyltrimethoxysilane for primary modification; 2) using methacrylate functional monomer for secondary modification. Specifically, 100g toluene, 55g γ-methacryloxypropyltrimethoxysilane and 4.7g, 1.9mol / L hydrochloric acid aqueous solution are added to 55g hydroxyl-terminated polydimethylsiloxane, and the temperature is raised to 95°C under uniform stirring, and the constant temperature stirring is continued for 8h, and the solution is placed at 85°C for vacuum rotary evaporation, and then 4% (w) 2-hydroxy-2-methylpropiophenone is added for ultrasonic dispersion for 30min to obtain γ-methacryloxypropyltrimethoxysilane-modified polydimethylsiloxane. 20g of methacrylate functional monomer is dispersed in 100g of organic solvent, 20g of polydimethylsiloxane modified by γ-methacryloxypropyltrimethoxysilane is added and stirred and mixed, and then 2% (w) of photoinitiator-184 is added and ultrasonically dispersed for 40 minutes to obtain modified polydimethylsiloxane. The modified polydimethylsiloxane is dispersed in polytetrafluoroethylene emulsion to obtain an inert barrier material.

[0026] A method for preparing a brominated butyl rubber piston for a prefilled syringe comprises the following steps:

[0027] A. Rubber mixing: the bio-based rubber, part of the brominated butyl rubber and carbon black are mixed in one stage, the remaining brominated butyl rubber, active magnesium oxide and white carbon black are added for the second stage, magnesium powder, titanium dioxide and talcum powder are added for the third stage, and finally the remaining raw materials except sulfur are added for the fourth stage; after cooling, sulfur is added for open mixing to obtain a rubber sheet; the mixing temperature is 80-90°C, the mixing time in the first stage is 1-3min, the mixing time in the second stage is 2-4min, the mixing time in the third stage is 3-6min, and the mixing time in the fourth stage is 5-9min; the open mixing temperature is 80-85°C, and the open mixing time is 9-13min.

[0028] B. Preforming: The film is calendered, vulcanized, punched and cleaned to obtain a prefabricated rubber piston; the calendering temperature is 80-100℃, the calendering speed is 10-40r / min; the vulcanization temperature is 175-200℃, the vulcanization time is 360-600s, and the vulcanization pressure is 80-150kg / cm2 .

[0029] C. Spraying and curing: spray the inert barrier material on the surface of the prefabricated rubber piston, dry and cure it to obtain the finished bromobutyl rubber piston. The drying temperature is 100-140℃ and the curing time is 8-24h.

[0030] The use of segmented mixing can improve the dispersion of raw materials in the rubber, make the rubber have better fluidity, and improve the mechanical properties, plasticity and processability of the rubber. The above preparation method can make the bromobutyl rubber piston have better sliding properties and higher solubility resistance, and can still remain stable in harsh environments such as strong acids and alkalis, and have good corrosion resistance.

[0031] Example 1

[0032] A brominated butyl rubber piston for a prefilled syringe comprises a base elastomer and an inert barrier film covering the surface of the base elastomer; the base elastomer comprises 80 g of brominated butyl rubber, 10 g of bio-based rubber (eucommia rubber), 0.5 g of polyisobutylene, 10 g of talcum powder, 20 g of calcined kaolin, 1 g of white carbon black, 2 g of black carbon black, 10 g of magnesium powder, 1 g of titanium dioxide, 0.3 g of sulfur, 3 g of active magnesium oxide, 1 g of polytetrafluoroethylene wax and 5 g of a fluorine-free lubricant; the inert barrier film is polytetrafluoroethylene modified with modified polydimethylsiloxane.

[0033] A method for preparing a brominated butyl rubber piston for a prefilled syringe comprises the following steps:

[0034] A. Rubber mixing: Turn on the power supply and compressed air of the kneading machine, and when the temperature reaches 85°C, put the bio-based rubber, part of the brominated butyl rubber and carbon black into the kneading machine for one-stage kneading for 1 minute, then add the remaining brominated butyl rubber, activated magnesium oxide and white carbon black for two-stage kneading for 2 minutes, then add magnesium powder, titanium dioxide and talcum powder for three-stage kneading for 3 minutes, and finally add the remaining raw materials except sulfur for four-stage kneading for 5 minutes;

[0035] After the internal mixing is completed, the rubber is discharged and sent to the open mixing mill through the lifting bucket. The rubber is repeatedly kneaded on the drum, cooled to 80°C, and sulfur is added to open the mixing mill for 9 minutes, and then thinned. After thinning twice, the material is discharged at 110°C to obtain a film.

[0036] B. Preforming: The film is conveyed to the feed port of the extruder, extruded at 80°C and then transferred to the three-roll calender, where it is squeezed by rollers at a calendering speed of 10r / min; the cooled semi-finished product is placed flat on the surface of the vulcanization mold and heated at 175°C and 80kg / cm 2 Vulcanize for 360 seconds; punch and clean to obtain a prefabricated rubber piston;

[0037] C. Spraying and curing: spraying polytetrafluoroethylene modified with modified polydimethylsiloxane on the surface of the prefabricated rubber piston, drying and curing at 100° C. for 8 hours to obtain a finished brominated butyl rubber piston.

[0038] Example 2

[0039] A brominated butyl rubber piston for a prefilled syringe comprises a base elastomer and an inert barrier film covering the surface of the base elastomer; the base elastomer comprises 100 g of brominated butyl rubber, 15 g of bio-based rubber (polylactic acid rubber), 2 g of polyisobutylene, 15 g of talcum powder, 25 g of calcined kaolin, 2 g of white carbon black, 3 g of black carbon black, 15 g of magnesium powder, 2 g of titanium dioxide, 0.4 g of sulfur, 7 g of active magnesium oxide, 2 g of polytetrafluoroethylene wax and 8 g of a fluorine-free lubricant; the inert barrier film is polytetrafluoroethylene modified with modified polydimethylsiloxane.

[0040] A method for preparing a brominated butyl rubber piston for a prefilled syringe comprises the following steps:

[0041] A. Rubber mixing: Turn on the power supply and compressed air of the kneading machine, and when the temperature reaches 88°C, put the bio-based rubber, part of the brominated butyl rubber and carbon black into the kneading machine for one-stage kneading for 2 minutes, then add the remaining brominated butyl rubber, activated magnesium oxide and white carbon black for two-stage kneading for 3 minutes, then add magnesium powder, titanium dioxide and talcum powder for three-stage kneading for 5 minutes, and finally add the remaining raw materials except sulfur for four-stage kneading for 7 minutes;

[0042] After the internal mixing is completed, the rubber is discharged and sent to the open mixing mill through the lifting bucket. The rubber is repeatedly kneaded on the drum, cooled to 80°C, and sulfur is added to open the mixing mill for 13 minutes. After thinning for 3 times, the rubber is discharged at 130°C to obtain a film.

[0043] B. Preforming: The film is conveyed to the feed port of the extruder, extruded at 90°C and then transferred to the three-roll calender, where it is extruded by rollers at a calendering speed of 20r / min; the cooled semi-finished product is placed flat on the surface of the vulcanization mold and heated at 185°C and 100kg / cm 2 Vulcanize for 500s; punch and clean to obtain a prefabricated rubber piston;

[0044] C. Spraying and curing: spray polytetrafluoroethylene modified with modified polydimethylsiloxane on the surface of the prefabricated rubber piston, dry and cure at 120° C. for 20 hours to obtain a finished brominated butyl rubber piston.

[0045] Example 3

[0046] A brominated butyl rubber piston for a prefilled syringe comprises a base elastomer and an inert barrier film covering the surface of the base elastomer; the base elastomer comprises 120 g of brominated butyl rubber, 20 g of bio-based rubber (polyhydroxyalkanoate rubber), 3 g of polyisobutylene, 20 g of talcum powder, 30 g of calcined kaolin, 3 g of white carbon black, 4 g of black carbon black, 20 g of magnesium powder, 3 g of titanium dioxide, 2 g of sulfur, 8 g of active magnesium oxide, 3 g of polytetrafluoroethylene wax and 10 g of a fluorine-free lubricant; the inert barrier film is polytetrafluoroethylene modified with modified polydimethylsiloxane.

[0047] A method for preparing a brominated butyl rubber piston for a prefilled syringe comprises the following steps:

[0048] A. Rubber mixing: Turn on the power supply and compressed air of the kneading machine, and when the temperature reaches 90°C, put the bio-based rubber, part of the brominated butyl rubber and carbon black into the kneading machine for one-stage kneading for 3 minutes, then add the remaining brominated butyl rubber, activated magnesium oxide and white carbon black for two-stage kneading for 4 minutes, then add magnesium powder, titanium dioxide and talcum powder for three-stage kneading for 6 minutes, and finally add the remaining raw materials except sulfur for four-stage kneading for 9 minutes;

[0049] After the internal mixing is completed, the rubber is discharged and sent to the open mixing mill through the lifting bucket. The rubber is repeatedly kneaded on the drum, cooled to 80°C, and sulfur is added to open the mixing mill for 10 minutes. After thinning for 3 times, the rubber is discharged at 145°C to obtain a film.

[0050] B. Preforming: The film is conveyed to the feed port of the extruder, extruded at 100°C and then transferred to the three-roll calender, where it is squeezed by rollers at a calendering speed of 40r / min; the cooled semi-finished product is placed flat on the surface of the vulcanization mold and heated at 200°C and 150kg / cm 2 Vulcanize for 600s; punch and clean to obtain a prefabricated rubber piston;

[0051] C. Spraying and curing: spray polytetrafluoroethylene modified with modified polydimethylsiloxane on the surface of the prefabricated rubber piston, dry and cure at 140°C for 24 hours to obtain a finished bromobutyl rubber piston.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Example 1 is that the polydimethylsiloxane in the inert barrier film is not modified.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Example 1 is that in the inert barrier film, the polydimethylsiloxane is modified only with γ-methacryloxypropyltrimethoxysilane.

[0056] Comparative Example 3

[0057] The difference between this comparative example and Example 1 is that in the inert barrier film, the polydimethylsiloxane is modified only with methacrylate functional monomers.

[0058] Comparative Example 4

[0059] The difference between this comparative example and Example 1 is that the inert barrier membrane is polytetrafluoroethylene.

[0060] Comparative Example 5

[0061] This comparative example is different from Example 1 in that no bio-based rubber is added.

[0062] Comparative Example 6

[0063] This comparative example is different from Example 1 in that no active magnesium oxide is added.

[0064] Comparative Example 7

[0065] In this comparative example, the ratio of sulfur to activated magnesium oxide is 1:80.

[0066] Comparative Example 8

[0067] The ratio of sulfur to activated magnesium oxide in this comparative example is 2:1.

[0068] Test example

[0069] The rubber pistons prepared in the examples and comparative examples were tested. The performance of the insoluble particles was tested according to the national drug packaging material standard "YBB00052005-2015", and the sliding force and the lasting force were tested according to the national standard GB15810. The test results are as follows:

[0070] Table 1 Rubber piston performance test results

[0071]

[0072] It can be seen from Table 1 that the rubber pistons of the embodiment and the comparative example all meet the standards. The rubber pistons prepared in the embodiment have lower sliding force and sustained force, less insoluble particles, and better performance of the rubber pistons.

[0073] In addition, the compatibility and biosafety of the rubber pistons of Examples 1-3 were tested in accordance with the national pharmaceutical packaging material standard "YBB00052005-2015". The test results all met the above standards.

[0074] According to the general rule 0401 of the fourth volume of the 2020 edition of the Chinese Pharmacopoeia, the absorbance of the rubber pistons prepared in Examples 1-3 and Comparative Examples 7-8 was measured, and the results were as follows:

[0075] Table 2 Absorbance detection results

[0076]

[0077] According to Table 2, the rubber piston of the embodiment has a smaller absorbance, which indicates that the rubber piston prepared in the embodiment has better quality and longer service life.

[0078] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A brominated butyl rubber piston for a prefilled syringe, characterized in that: The invention comprises a base elastomer and an inert barrier film covering the surface of the base elastomer; the base elastomer comprises, by weight, 80-120 parts of brominated butyl rubber, 10-20 parts of bio-based rubber, 0.5-3 parts of polyisobutylene, 10-20 parts of talc, 20-30 parts of calcined kaolin, 3-7 parts of carbon black, 10-20 parts of magnesium powder, 1-3 parts of titanium dioxide, 0.3-2 parts of sulfur, 3-8 parts of active magnesium oxide, 1-3 parts of polytetrafluoroethylene wax and 5-10 parts of a lubricant; the inert barrier film is polytetrafluoroethylene modified with modified polydimethylsiloxane.

2. The brominated butyl rubber piston for a prefilled syringe according to claim 1, characterized in that: The bio-based rubber is one or more of eucommia rubber, polylactic acid rubber and polyhydroxyalkanoate rubber.

3. The brominated butyl rubber piston for a prefilled syringe according to claim 2, characterized in that: The carbon black comprises 1-3 parts of white carbon black and 2-4 parts of black carbon black by weight, and the lubricant is a fluorine-free lubricant.

4. The brominated butyl rubber piston for a prefilled syringe according to claim 2 or 3, characterized in that: The modification method of the modified polydimethylsiloxane comprises: 1) using γ-methacryloxypropyltrimethoxysilane for primary modification; 2) using methacrylate functional monomer for secondary modification.

5. The method for preparing the brominated butyl rubber piston for a prefilled syringe according to claim 3, characterized in that: The following steps are involved: A. Rubber refining: the bio-based rubber, part of the brominated butyl rubber and carbon black are subjected to a first-stage internal refining, the remaining brominated butyl rubber, active magnesium oxide and white carbon black are added for a second-stage internal refining, magnesium powder, titanium dioxide and talcum powder are added for a third-stage internal refining, and finally the remaining raw materials except sulfur are added for a fourth-stage internal refining; after cooling, sulfur is added for open refining to obtain a rubber sheet; B. Preforming: calendaring, vulcanizing, punching and cleaning the film to obtain a prefabricated rubber piston; C. Spraying and curing: spray inert barrier material on the surface of prefabricated rubber piston, dry and cure, and obtain the finished bromobutyl rubber piston.

6. The method for preparing the brominated butyl rubber piston for a prefilled syringe according to claim 5, characterized in that: The banburying temperature is 80-90°C, the first banburying time is 1-3min, the second banburying time is 2-4min, the third banburying time is 3-6min, and the fourth banburying time is 5-9min; the open-mixing temperature is 80-85°C, and the open-mixing time is 9-13min.

7. The method for preparing the brominated butyl rubber piston for a prefilled syringe according to claim 5, characterized in that: The calendering temperature is 80-100℃, the calendering speed is 10-40r / min; the vulcanization temperature is 175-200℃, the vulcanization time is 360-600s, and the vulcanization pressure is 80-150kg / cm 2 .

8. The method for preparing the brominated butyl rubber piston for a prefilled syringe according to claim 5, characterized in that: The drying temperature is 100-140℃ and the curing time is 8-24h.

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