High-elasticity and high-stability PVC granules, preparation method and application thereof

Abstract

The application belongs to the technical field of polymer material modification, and relates to high-elasticity and high-stability PVC granules, a preparation method thereof and application in medical catheters. The granules are prepared from 100 parts of PVC resin powder, 50-60 parts of plasticizer, 5-10 parts of epoxy soybean oil, 0.6-1.5 parts of composite heat stabilizer, 0.4-6 parts of elastomer, 0.4-0.8 parts of processing aid and 0.1-0.4 parts of lubricant as raw materials. The raw materials are pre-plasticized, then melt-extruded by an extruder and granulated to form the granules. The granules are melt-extruded twice to form a high-elasticity and high-stability medical catheter body, and the medical catheter body is assembled to form a medical catheter product. The medical catheter product includes infusion, nursing or implantation medical catheters. The high-elasticity and high-stability PVC granules have excellent elasticity, tensile toughness, heat stability and long-term stability, and can endow the medical catheter product with excellent elasticity and stability.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, and relates to a high-elasticity and high-stability PVC granule, its preparation method, and its application in medical catheters. Background Technology

[0002] Polyvinyl chloride (PVC) is one of the world's five major general-purpose plastics, widely used in various fields, and ranks second in production volume. It possesses excellent insulation and flame-retardant properties. However, due to certain unavoidable structural defects in PVC produced in traditional industrial sectors, PVC undergoes degradation processes such as yellowing and discoloration when exposed to external factors like light, oxygen, and heat during use. This reduces the original properties of PVC and limits its applications. Therefore, it is necessary to improve the thermal stability of PVC.

[0003] It is generally believed that PVC degradation occurs through a dehydrochlorination reaction of the PVC molecular chain, forming double bonds and accelerating the degradation process. As the dehydrochlorination reaction proceeds, the conjugated double bonds on the PVC molecular chain gradually increase in length, resulting in a change in the color of the PVC material, with the color gradually deepening. Furthermore, the hydrogen chloride released during PVC degradation has a catalytic effect on PVC degradation, further accelerating it. Through patent and literature research, the main existing methods for thermally stabilizing PVC materials are: firstly, rapidly replacing the allyl chloride on the PVC molecular chain to inhibit the growth of conjugated double bonds, fundamentally improving the thermal stability of PVC and preventing discoloration; and secondly, timely absorbing the hydrogen chloride released during PVC degradation to prevent its catalytic effect on PVC degradation, thereby slowing down the degradation process. Currently, the main method for improving the thermal stability of PVC is to add a certain amount of heat stabilizer to delay its thermal degradation.

[0004] Commonly used heat stabilizers include lead salts, metal soaps, organotin compounds, and rare earth heat stabilizers. However, lead salt heat stabilizers used in traditional industrial production are too toxic and easily cause heavy metal pollution. Metal soap heat stabilizers have poor compatibility with resin matrices and are difficult to process. Organotin heat stabilizers are expensive, have a strong odor during processing, and are prone to pollution. Rare earth heat stabilizers are also restricted in their use due to regulations. Research on nitrogen-containing organic heat stabilizers has received significant attention, but most organic heat stabilizers are small molecule compounds. Small molecule heat stabilizers are prone to precipitation, and their effect on improving the thermal stability of PVC is generally limited. Furthermore, their initial whiteness is usually poor, and their inherent color can sometimes affect the color of PVC products, resulting in insufficient long-term stability.

[0005] Different PVC-based products have varying performance and functional requirements due to different application environments, such as high transparency and high elasticity. However, achieving these specific functions often compromises these properties, leading to decreased tensile toughness and hindering its application in high-performance medical products. For instance, medical catheters may experience deformation due to stockpiling during production and storage. Poor elasticity can cause these catheters to fold, affecting assembly and bonding, and in severe cases, even melting off. If this occurs during blood transfusions, it can threaten the patient's life. Therefore, improving the long-term thermal stability of PVC materials while simultaneously enhancing their elasticity is crucial for improving product performance and applications. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a highly elastic and stable PVC granule, which possesses excellent elastic properties, thermal stability, and long-term stability.

[0007] This invention also provides a method for preparing the above-mentioned high-elasticity and high-stability PVC granules and their application in medical device products.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] This invention provides a high-elasticity and high-stability PVC granule, the main raw materials of which include: 100 parts of PVC resin powder, 50-60 parts of plasticizer, 5-10 parts of epoxidized soybean oil, 0.6-1.5 parts of composite heat stabilizer, 0.4-6 parts of elastomer, 0.4-0.8 parts of processing aid, and 0.1-0.4 parts of lubricant; the raw materials are in parts by weight.

[0010] Further, the composite heat stabilizer comprises 5-7 parts of a primary stabilizer and 3-5 parts of an auxiliary stabilizer; the primary stabilizer is composed of zinc stearate and calcium stearate in a mass ratio of 1:1-5, and the auxiliary stabilizer comprises phenyl diisooctyl phosphite; the components are in parts by weight; the elastomer comprises chlorinated polyethylene, PVC elastomer, or nitrile rubber; preferably, the chlorinated polyethylene and nitrile rubber are liquids, and the PVC elastomer is a powder.

[0011] Furthermore, the processing aid is formed by compounding acrylate copolymers of different molecular weights, wherein the acrylate copolymers are ACR copolymers. The different molecular weights refer to high molecular weight, medium molecular weight, and low molecular weight, preferably high molecular weight 15,000-30,000, medium molecular weight 10,000-15,000, and low molecular weight <10,000; wherein the compounded ACR copolymers are preferably compounded in a high molecular weight, medium molecular weight, and low molecular weight mass ratio of 2:2:1; or a high molecular weight to low molecular weight mass ratio of 3:1; or a medium molecular weight to low molecular weight mass ratio of 3:1; wherein the high molecular weight ACR copolymer provides toughening and impact resistance, the medium molecular weight ACR copolymer enhances melt strength, promotes plasticization and shortens processing time, and the low molecular weight ACR copolymer provides auxiliary lubrication.

[0012] Further, the average degree of polymerization of the PVC resin powder is 1800-2500, preferably 2500; the plasticizer is an environmentally friendly non-phthalic plasticizer, including diisooctyl terephthalate (DOTP), dioctyl adipate (DOA), or trioctyl trimellitate (TOTM); the lubricant includes any one or more of oxidized polyethylene wax, stearic acid, and benzyl silicone oil.

[0013] The present invention also provides a method for preparing high-elasticity and high-stability PVC granules, comprising the following steps: S1, first mixing solid raw materials, then mixing liquid raw materials and mixing them with solid raw materials in batches, controlling the mixing process to obtain pre-plasticized raw materials; S2, melting and extruding the pre-plasticized raw materials through an extruder and granulating them to obtain the final product.

[0014] Furthermore, the solid raw materials include PVC resin powder, stabilizers (zinc stearate, calcium stearate), processing aids (acrylate copolymers), lubricants (oxidized polyethylene wax, stearic acid), and powdered PVC elastomer; the liquid raw materials include plasticizers (diisooctyl phthalate (DOTP), dioctyl adipate (DOA), or trioctyl trimellitate (TOTM)), epoxidized soybean oil, stabilizers (diisooctyl phosphite), elastomers (liquid chlorinated polyethylene, liquid nitrile rubber), and lubricants (phenylmethyl silicone oil).

[0015] Further, the mixing process described in S1 includes: S11, adding the solid raw material into a high-speed mixing pot, setting the mixing speed to 200-300 rpm / min, and adding 50%-80% of the liquid raw material after the solid raw material is heated to 50-80℃; S12, adding the remaining liquid raw material after the temperature rises back to 65-85℃, continuing to stir and heat to 90-110℃, setting the mixing speed to 700-900 rpm / min, and discharging the material after the material temperature rises to 120-135℃, and finally cooling it to 45-65℃.

[0016] Furthermore, the granulation conditions of the extruder described in S2 are as follows: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extrusion temperature 80-120℃.

[0017] The present invention further provides the application of highly elastic and stable PVC granules in the preparation of medical catheter bodies or catheters.

[0018] The present invention further provides a high-elasticity and high-stability medical catheter body, wherein the high-elasticity and high-stability PVC granules are prepared by melt extrusion molding. The extrusion molding conditions are: main machine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0019] Finally, the present invention provides a highly elastic and stable medical catheter, which is assembled from the highly elastic and stable medical catheter body as the main component.

[0020] Furthermore, the highly elastic and stable medical catheter includes infusion, nursing, or implantable medical catheters.

[0021] The beneficial effects of this invention are:

[0022] 1. In this invention, the elastomer, high-polymerization-degree plasticizer, stabilizer, and processing aids in the high-elasticity, high-stability PVC granules are rationally proportioned, exhibiting a synergistic effect. They simultaneously provide synergistic plasticization, synergistic stabilization, and optimized dimensional stability, complementing each other to optimize material performance. Furthermore, the lubricating processing aids and lubricants also have a synergistic effect, facilitating secondary processing of the product, increasing the melt flowability of the granules, thereby increasing traction speed, improving production capacity, and saving energy and reducing consumption.

[0023] 2. The high-elasticity, high-stability PVC granules of this invention use environmentally friendly non-phthalic plasticizers instead of phthalic plasticizers, greatly improving the elasticity of PVC to the level of an elastomer. Its unique high resilience and flexibility allow it to better adapt to infusion, nursing, or implantable medical catheters. Simultaneously, it overcomes the harm to the human body caused by phthalic plasticizers in existing PVC granules, eliminates the possibility of thrombosis caused by the migration of phthalic plasticizers in PVC granules, and avoids the possibility that phthalic plasticizers may be carcinogenic and harmful to the human body.

[0024] 3. In this invention, the pre-plasticization of high-elasticity and high-stability PVC granules adopts a batch-by-batch liquid addition process, which helps to fully absorb the liquid in the raw materials, resulting in better plasticization effect, lower secondary processing temperature of the products, and energy saving and consumption reduction. In addition, color powder can be added as needed during processing to obtain products of different colors. The use of liquid stirring tank in this invention can also avoid uneven dispersion of color powder caused by suspension, resulting in better color consistency of the obtained products.

[0025] 4. The reasonable combination of pre-plasticization process conditions and granulation conditions of the high-elasticity and high-stability PVC granules in this invention helps to further improve the plasticization effect and can effectively solve the appearance defects such as black spots, crystal points, and bubbles on the surface of pipe products.

[0026] 5. The high-elasticity and high-stability PVC granules in this invention have excellent thermal stability, which can improve the production stability and continuity during secondary processing, thereby reducing problems such as filter clogging and traction speed reduction caused by aging or scorching, and thus improving production efficiency and increasing production capacity.

[0027] 6. The high-elasticity and high-stability PVC granules in this invention also have excellent elasticity and tensile toughness, making it less likely for processed products to develop wrinkles, bends or other appearance defects during storage. In addition, during product application, it can reduce the problem of poor liquid flow caused by product deformation due to accidental pressure by users.

[0028] 7. The high-elasticity and high-stability medical catheter body of the present invention has a low glass transition temperature, which achieves a cold-resistant effect, which is beneficial for the transportation of the product under cold conditions and avoids loss due to brittle fracture. Attached Figure Description

[0029] To more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Appendix Figure 1 The image shows a high-elasticity, high-stability PVC granule product from the embodiments.

[0031] Appendix Figure 2 These are diagrams illustrating the bending performance tests of medical catheter bodies in the embodiments and comparative examples;

[0032] Appendix Figure 3 The graph shows the thermal stability test results of the granular products in the examples and comparative examples;

[0033] Appendix Figure 4 The images show the external appearance of the medical catheter body in the embodiments and comparative examples. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All mentioned embodiments are implemented based on the technical solutions of the present invention, and detailed implementation processes are given. However, it should be stated that the scope of protection of the present invention is not limited to the following embodiments.

[0035] The high-elasticity, high-stability PVC granules of this invention mainly consist of: 100 parts PVC resin powder, 50-60 parts plasticizer, 5-10 parts epoxidized soybean oil, 0.6-1.5 parts composite heat stabilizer, 0.4-6 parts elastomer, 0.4-0.8 parts processing aid, and 0.1-0.4 parts lubricant; the raw materials are by weight. First, the solid raw materials are mixed and added to a high-speed mixing pot. Then, the liquid raw materials are mixed and added to the solid raw materials in two batches, controlling the mixing process in the high-speed mixing pot to obtain pre-plasticized raw materials. Finally, the pre-plasticized raw materials are melt-extruded and granulated using an extruder to obtain the final product. The obtained high-elasticity, high-stability PVC granules can be melt-extruded to produce high-elasticity, high-stability medical catheter bodies. These bodies can be assembled to obtain medical catheter products, including infusion, nursing, or implantable medical catheters.

[0036] The raw materials used in the examples and comparative examples are described below, but are not limited to these raw materials. All raw materials can be commercially available: Resin powder: PVC resin powder, average degree of polymerization 2500; Elastomer: Powdered PVC elastomer, liquid nitrile rubber, liquid chlorinated polyethylene; Composite heat stabilizer (main stabilizer and auxiliary stabilizer are compounded in proportion): Main stabilizer zinc stearate, calcium stearate; Auxiliary stabilizer: Phosphite-diisooctyl phthalate; Processing aid: formed by compounding acrylate copolymers (ACR) of different molecular weights. In this invention, three models of PA-40 (high molecular weight), PA-20 (medium molecular weight), and PA-101 (low molecular weight) from Kaneka Corporation of Japan are used for compounding; Lubricant: Oxidized polyethylene wax, stearic acid, benzyl silicone oil; Plasticizer: Trioctyl trimellitate (TOTM), dioctyl terephthalate (DOTP), dioctyl adipate (DOA), dioctyl phthalate (DOP).

[0037] Example 1

[0038] Preparation of high-elasticity and high-stability PVC granules

[0039] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 0.6 parts of composite heat stabilizer (including 0.06 parts of zinc stearate and 0.18 parts of calcium stearate), 2 parts of powdered PVC elastomer, 0.4 parts of processing aids (including 0.1 parts of PA-101 and 0.3 parts of PA-40), and 0.1 parts of lubricant oxidized polyethylene wax. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 60 parts of DOTP, 5 parts of epoxidized soybean oil, and 0.36 parts of phenyl diisooctyl phosphite. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 200 rpm / min. When the material temperature rises to 50°C, start adding liquid at 50% of the total volume. When the temperature rises back to 80°C, add the remaining 50% of the liquid. Continue stirring until the temperature rises to 85°C, then switch to high-speed stirring at 700 rpm / min. When the material temperature rises to 120°C, discharge the material. Set the cooling temperature to 45°C and set it for later use.

[0040] Granulation: The pre-plasticized raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0041] Preparation of high-elasticity and high-stability medical catheter body

[0042] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0043] Example 2

[0044] Preparation of high-elasticity and high-stability PVC granules

[0045] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 0.8 parts of composite heat stabilizer (including 0.08 parts of zinc stearate and 0.24 parts of calcium stearate), 3 parts of powdered PVC elastomer, 0.6 parts of processing aids (including 0.15 parts of PA-101 and 0.45 parts of PA-20), and 0.2 parts of lubricant stearic acid. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 56 parts of DOTP, 6 parts of epoxidized soybean oil, and 0.48 parts of phenyl diisooctyl phosphite. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 250 rpm / min. When the material temperature rises to 60°C, start adding liquid at 60% of the total volume. When the temperature rises back to 80°C, add the remaining 40% of the liquid. Continue stirring until the temperature rises to 100°C, then switch to high-speed stirring at 750 rpm / min. When the material temperature rises to 125°C, discharge the material. Set the cooling temperature to 50°C and set it for later use.

[0046] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0047] Preparation of high-elasticity and high-stability medical catheter body

[0048] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0049] Example 3:

[0050] Preparation of high-elasticity and high-stability PVC granules

[0051] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 1.0 part of composite heat stabilizer (including 0.1 parts of zinc stearate and 0.3 parts of calcium stearate), 0.8 parts of processing aids (including 0.16 parts of PA-101, 0.32 parts of PA-20, and 0.32 parts of PA-40), 0.1 parts of lubricant oxidized polyethylene wax, and 0.2 parts of lubricant stearic acid. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 57 parts of DOA, 7 parts of epoxidized soybean oil, 0.6 parts of phosphite-phenylenediisooctyl ester, and 6 parts of liquid chlorinated polyethylene (elastomer). Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 300 rpm / min. When the material temperature rises to 80℃, start adding liquid at 70% of the total volume. When the temperature rises back to 75℃, add the remaining 30% of the liquid. Continue stirring until the temperature rises to 110℃, then switch to high-speed stirring at 800 rpm / min. When the material temperature rises to 135℃, discharge the material and set the cooling temperature to 60℃ for later use.

[0052] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0053] Preparation of high-elasticity and high-stability medical catheter body

[0054] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0055] Example 4:

[0056] Preparation of high-elasticity and high-stability PVC granules

[0057] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 1.2 parts of composite heat stabilizer (including 0.12 parts of zinc stearate and 0.36 parts of calcium stearate), 0.5 parts of processing aid (including 0.125 parts of PA-101 and 0.375 parts of PA-40), 0.2 parts of lubricant oxidized polyethylene wax, and 0.2 parts of lubricant stearic acid. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 50 parts of TOTM, 8 parts of epoxidized soybean oil, 0.72 parts of phosphite-phenylenediisooctyl ester, and 4 parts of liquid chlorinated polyethylene. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 200 rpm / min. When the material temperature rises to 80°C, start adding liquid at 80% of the total volume. When the temperature rises back to 75°C, add the remaining 20% ​​of the liquid. Continue stirring until the temperature rises to 100°C, then switch to high-speed stirring at 850 rpm / min. When the material temperature rises to 130°C, discharge the material and set the cooling temperature to 65°C for later use.

[0058] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0059] Preparation of high-elasticity and high-stability medical catheter body

[0060] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0061] Example 5:

[0062] Preparation of high-elasticity and high-stability PVC granules

[0063] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 1.4 parts of composite heat stabilizer (including 0.14 parts of zinc stearate and 0.42 parts of calcium stearate), 0.7 parts of processing aids (including 0.14 parts of PA-101, 0.28 parts of PA-20, and 0.28 parts of PA-40), and 0.2 parts of lubricant oxidized polyethylene wax. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 56 parts of TOTM, 9 parts of epoxidized soybean oil, 0.84 parts of phenyl diisooctyl phosphite, and 0.4 parts of liquid nitrile rubber. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 300 rpm / min. When the material temperature rises to 50°C, start adding liquid at 50% of the total volume. When the temperature rises back to 80°C, add the remaining 50% of the liquid. Continue stirring until the temperature rises to 85°C, then switch to high-speed stirring at 900 rpm / min. When the material temperature rises to 120°C, discharge the material. Set the cooling temperature to 45°C and set it for later use.

[0064] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0065] Preparation of high-elasticity and high-stability medical catheter body

[0066] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0067] Example 6:

[0068] Preparation of high-elasticity and high-stability PVC granules

[0069] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 1.5 parts of composite heat stabilizer (including 0.15 parts of zinc stearate and 0.45 parts of calcium stearate), 4 parts of powdered PVC elastomer, 0.4 parts of processing aids (including 0.1 parts of PA-101 and 0.3 parts of PA-20), and 0.1 parts of lubricant oxidized polyethylene wax. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 52 parts of TOTM, 10 parts of epoxidized soybean oil, and 0.9 parts of phenyl diisooctyl phosphite. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 200 rpm / min. When the material temperature rises to 60℃, start adding liquid at 60% of the total volume. When the temperature rises back to 80℃, add the remaining 40% of the liquid. Continue stirring until the temperature rises to 100℃, then switch to high-speed stirring at 900 rpm / min. When the material temperature rises to 125℃, discharge the material. Set the cooling temperature to 50℃ and set it for later use.

[0070] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0071] Preparation of high-elasticity and high-stability medical catheter body

[0072] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0073] Example 7:

[0074] Preparation of high-elasticity and high-stability PVC granules

[0075] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 1.4 parts of composite heat stabilizer (including 0.14 parts of zinc stearate and 0.42 parts of calcium stearate), 5 parts of powdered PVC elastomer, 0.6 parts of processing aids (including 0.15 parts of PA-101 and 0.45 parts of PA-40), and 0.2 parts of lubricant stearic acid. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 55 parts of TOTM, 9 parts of epoxidized soybean oil, and 0.84 parts of phenyl diisooctyl phosphite. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 300 rpm / min. When the material temperature rises to 60°C, start adding liquid at 60% of the total volume. When the temperature rises back to 80°C, add the remaining 40% of the liquid. Continue stirring until the temperature rises to 100°C, then switch to high-speed stirring at 800 rpm / min. When the material temperature rises to 125°C, discharge the material. Set the cooling temperature to 50°C and set it for later use.

[0076] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0077] Preparation of high-elasticity and high-stability medical catheter body

[0078] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0079] Example 8:

[0080] Preparation of high-elasticity and high-stability PVC granules

[0081] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 1.2 parts of composite heat stabilizer (including 0.12 parts of zinc stearate and 0.36 parts of calcium stearate), 0.8 parts of processing aids (including 0.16 parts of PA-101, 0.32 parts of PA-20, and 0.32 parts of PA-40), 0.1 parts of lubricant benzyl silicone oil, and 0.2 parts of lubricant oxidized polyethylene wax. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 55 parts of TOTM, 8 parts of epoxidized soybean oil, 0.72 parts of phosphite-phenylenediisooctyl ester, and 0.6 parts of liquid nitrile rubber. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 250 rpm / min. When the material temperature rises to 80°C, start adding liquid at 70% of the total volume. When the temperature rises back to 75°C, add the remaining 30% of the liquid. Continue stirring until the temperature rises to 110°C, then switch to high-speed stirring at 800 rpm / min. When the material temperature rises to 135°C, discharge the material. Set the cooling temperature to 60°C and set it for later use.

[0082] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0083] Preparation of high-elasticity and high-stability medical catheter body

[0084] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0085] Example 9:

[0086] Preparation of high-elasticity and high-stability PVC granules

[0087] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 1.0 part of composite heat stabilizer (including 0.1 parts of zinc stearate and 0.3 parts of calcium stearate), 0.7 parts of processing aids (including 0.175 parts of PA-101 and 0.525 parts of PA-20), 0.2 parts of lubricant oxidized polyethylene wax, and 0.2 parts of lubricant stearic acid. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 55 parts of TOTM, 7 parts of epoxidized soybean oil, 0.6 parts of phosphite-phenylenediisooctyl ester, and 0.4 parts of liquid nitrile rubber. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 200 rpm / min. When the material temperature rises to 80°C, start adding liquid at 80% of the total volume. When the temperature rises back to 75°C, add the remaining 20% ​​of the liquid. Continue stirring until the temperature rises to 100°C, then switch to high-speed stirring at 800 rpm / min. When the material temperature rises to 130°C, discharge the material and set the cooling temperature to 65°C for later use.

[0088] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0089] Preparation of high-elasticity and high-stability medical catheter body

[0090] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0091] Example 10:

[0092] Preparation of high-elasticity and high-stability PVC granules

[0093] Raw material pre-plasticization: Weigh the solid raw materials: 100 parts of polyvinyl chloride resin, 0.6 parts of composite heat stabilizer (including 0.06 parts of zinc stearate and 0.18 parts of calcium stearate), 0.5 parts of processing aid (including 0.125 parts of PA-101 and 0.375 parts of PA-40), and 0.2 parts of lubricant oxidized polyethylene wax. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the liquid additives: 58 parts of DOA, 5 parts of epoxidized soybean oil, 0.36 parts of phosphite-phenylenediisooctyl ester, and 4 parts of liquid chlorinated polyethylene. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 250 rpm / min. When the material temperature rises to 50°C, start adding liquid at 50% of the total volume. When the temperature rises back to 80°C, add the remaining 50% of the liquid. Continue stirring until the temperature rises to 85°C, then switch to high-speed stirring at 700 rpm / min. When the material temperature rises to 120°C, discharge the material. Set the cooling temperature to 45°C and set it for later use.

[0094] Granulation: The pre-plasticized PVC raw material is melt-extruded through an extruder and granulated to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0095] Preparation of high-elasticity and high-stability medical catheter body

[0096] High-elasticity and high-stability PVC granules are melt-extruded twice to obtain a high-elasticity and high-stability medical catheter body. The extruder operating conditions are: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0097] Comparative Example 1

[0098] For the pre-plasticization of PVC granules used in ordinary pipe bodies, weigh the following solid raw materials: 100 parts of polyvinyl chloride resin, 0.2 parts of zinc stearate, 0.4 parts of calcium stearate, 0.4 parts of PA-20, and 0.2 parts of oxidized polyethylene wax (a lubricant). Pour the weighed raw materials into a high-speed mixing pot. Then weigh the following liquid additives: 55 parts of dioctyl phthalate (DOP) and 5 parts of epoxidized soybean oil. Pour the weighed liquid additives into a liquid mixing tank. Start the high-speed mixing pot and set the mixing conditions to: low-speed mixing at 200 rpm / min. When the material temperature reaches 60°C, begin adding liquid in one go. Continue mixing until the temperature reaches 110°C, then switch to high-speed mixing at 700 rpm / min. When the material temperature reaches 122°C, discharge the material and set the cooling temperature to 45°C for later use.

[0099] The PVC granules for pipe bodies are prepared by melting and extruding pre-plasticized PVC raw materials through an extruder, followed by granulation to obtain the PVC granules for pipe bodies. The granulation conditions of the extruder are: main machine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 90-125℃.

[0100] The PVC pipe body is prepared by secondary melt extrusion molding of high-elasticity and high-stability PVC granules. The operating conditions of the extruder are: main machine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 140-165℃.

[0101] Comparative Example 2

[0102] For the pre-plasticization of PVC granules for the stability pipe body, weigh the following solid raw materials: 100 parts of polyvinyl chloride resin, 0.7 parts of composite heat stabilizer (including 0.07 parts of zinc stearate and 0.21 parts of calcium stearate), 0.4 parts of processing aids (including 0.08 parts of PA-101, 0.16 parts of PA-20, and 0.16 parts of PA-40), and 0.1 parts of lubricant oxidized polyethylene wax. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the following liquid additives: 60 parts of dioctyl phthalate (DOP), 6 parts of epoxidized soybean oil, and 0.42 parts of diisooctyl phosphite. Pour the weighed liquid additives into a liquid mixing tank. Turn on the high-speed mixing pot switch and set the mixing conditions as follows: low-speed stirring at 250 rpm / min. When the material temperature reaches 60°C, start adding liquid in one go. Continue stirring until the temperature reaches 110°C, then switch to high-speed stirring at 800 rpm / min. When the material temperature reaches 122°C, discharge the material and set the cooling temperature to 45°C for later use.

[0103] The PVC granules for pipe bodies are prepared by melting and extruding pre-plasticized PVC raw materials through an extruder, followed by granulation to obtain high-elasticity and high-stability PVC granules. The granulation conditions of the extruder are: main engine speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 100-130℃.

[0104] The stable PVC tubing was prepared by secondary melt extrusion molding of PVC granules to obtain a highly elastic and stable medical catheter tubing. The extruder operating conditions were: main engine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 140-165℃.

[0105] Comparative Example 3

[0106] For the pre-plasticization of PVC granules for the elastic tube body, weigh the following solid raw materials: 100 parts of polyvinyl chloride resin, 0.12 parts of zinc stearate, 0.36 parts of calcium stearate, 0.4 parts of PA-40, 0.2 parts of lubricant oxidized polyethylene wax, and 3 parts of powdered PVC elastomer. Pour the weighed raw materials into a high-speed mixing pot. Then weigh the following liquid additives: 60 parts of dioctyl phthalate (DOP), 5 parts of epoxidized soybean oil, and 0.5 parts of diisooctyl phosphite. Pour the weighed liquid additives into a liquid mixing tank. Start the high-speed mixing pot switch and set the mixing conditions to: low-speed mixing at 300 rpm / min. When the material temperature reaches 60°C, begin adding liquid in one go. Continue mixing until the temperature reaches 110°C, then switch to high-speed mixing at 900 rpm / min. When the material temperature reaches 122°C, discharge the material and set the cooling temperature to 45°C for later use.

[0107] The preparation of PVC granules for elastic tubes involves melting and extruding pre-plasticized PVC raw materials through an extruder, followed by granulation to obtain PVC granules for elastic tubes. The granulation conditions of the extruder are: main extruder speed 260±20 rpm / min, feeding speed 160±20 rpm / min, pelletizing speed 250±20 rpm / min, and extruder temperature 80-120℃.

[0108] The PVC pipe body is prepared by secondary melt extrusion molding of PVC granules to obtain an elastic PVC pipe body. The operating conditions of the extruder are: main machine speed 55±5 rpm / min, traction speed 60±5 rpm / min, and extruder temperature 135-155℃.

[0109] Implementation effect analysis

[0110] The test methods for the granular properties in the examples and comparative examples are as follows:

[0111] (1) The ultraviolet absorbance was tested according to the chemical analysis method in GB / T 14233.1-2008. The granules were pressed into 300cm³ pieces. 2 The sample pieces were evenly cut into 1cm pieces. 2 After preparing the test sample, the test solution was used to test the precipitation of additives in the test material;

[0112] (2) Tensile properties were tested according to GB / T 1040.2-2006. The granules were made into standard test strips with a thickness of 2 mm.

[0113] (3) The rebound performance shall be tested by sample preparation in accordance with the method of GB / T 1681-2009, and the elasticity of the standard sample shall be tested;

[0114] (4) Melt flow index (MFR) is tested on granules in accordance with GB / T 3682.1-2018 Plastics Thermoplastics Determination of melt mass flow rate (MFR) and melt volume flow rate (MVR) Part 1: Standard methods.

[0115] (5) Thermal stability test shall be conducted in accordance with the method of GB / T 2917.1-2002, and the stability of the test sample at 180℃ shall be tested.

[0116] The test results are shown in Table 1 below:

[0117]

[0118] As shown in Table 1, the high-elasticity and high-stability PVC granules (such as those obtained by the preparation method of this invention) Figure 1 The granular product shown in the image possesses excellent performance. Its average UV absorbance is 0.12, significantly lower than the comparative example's 0.17, indicating a substantial reduction in the probability of additive precipitation, making it safer for use in medical devices where it comes into contact with the human body. The average elongation at break is 433.69%, far exceeding the comparative example's 272.43%, and the average resilience is 29.56%, significantly higher than the comparative example's 17.56%, fully demonstrating the material's excellent elasticity and tensile toughness. Combined with... Figure 2 It can be seen that medical catheters made from this material are less prone to appearance defects such as wrinkles and bends during storage, and can reduce the problem of poor liquid flow caused by product deformation due to accidental pressure during product application.

[0119] As can be seen from the melt flow index data in Table 1, the melt flow index of the high-elasticity and high-stability PVC granules in this invention is significantly improved, with an average melt flow index of 4.79 g / 10 min, far exceeding the 2.46 g / 10 min of the comparative example. The elastomer in the high-elasticity and high-stability PVC granules of this invention exhibits a synergistic effect with the high-polymerization-degree plasticizer, stabilizer, and processing aids, simultaneously providing synergistic plasticizing, synergistic stabilizing, and dimensional stability optimization effects. These elements complement each other, working together to optimize the material's performance. Furthermore, the lubricating processing aids and lubricants also have a synergistic effect, facilitating secondary processing of the product, increasing the melt flowability of the granules, thereby increasing traction speed, improving production capacity, and saving energy and reducing consumption.

[0120] Combining the thermal stability data in Table 1 and Figure 3The test results show that the comparative sample showed a significant color darkening after about one hour, while the high-elasticity, high-stability PVC granules in this invention exhibit excellent thermal stability, which can improve the production stability and continuity during secondary processing. This reduces problems such as filter clogging and decreased traction speed caused by aging or scorching, thereby improving production efficiency and increasing capacity. Figure 4 As shown, the reasonable combination of pre-plasticization process conditions and granulation conditions of the high-elasticity and high-stability PVC granules in this invention helps to further improve the plasticization effect and can effectively solve the appearance defects such as black spots, crystal points, and bubbles on the surface of pipe products.

[0121] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing high-elasticity and high-stability PVC granules, characterized in that, Includes the following steps: S1, first mix the solid raw materials, then mix the liquid raw materials and mix them with the solid raw materials in batches, control the mixing process, and obtain the pre-plasticized raw materials; S2, the pre-plasticized raw material is obtained by melt extrusion and granulation using an extruder; wherein: The mixing process described in S1 includes: S11, adding the solid raw material into a high-speed mixing pot, setting the mixing speed to 200-300 rpm, and adding 50%-80% of the liquid raw material after the solid raw material is heated to 50-80℃; S12, adding the remaining liquid raw material after the temperature rises back to 65-85℃, continuing to stir and heat to 90-110℃, setting the mixing speed to 700-900 rpm, and discharging the material after the material temperature rises to 120-135℃, and finally cooling it to 45-65℃; The granulation conditions of the extruder described in S2 are: main machine speed 260±20rpm, feeding speed 160±20rpm, pelletizing speed 250±20rpm, and extrusion temperature 80-120℃. The main raw materials of the high-elasticity and high-stability PVC granules include: 100 parts PVC resin powder, 50-60 parts plasticizer, 5-10 parts epoxidized soybean oil, 0.6-1.5 parts composite heat stabilizer, 0.4-6 parts elastomer, 0.4-0.8 parts processing aid, and 0.1-0.4 parts lubricant; the raw materials are in parts by weight. The composite heat stabilizer comprises 5-7 parts of a primary stabilizer and 3-5 parts of an auxiliary stabilizer; the primary stabilizer is composed of zinc stearate and calcium stearate in a mass ratio of 1:1-5, and the auxiliary stabilizer includes phenyl diisooctyl phosphite; the components are in parts by weight; the elastomer includes chlorinated polyethylene, PVC elastomer, or nitrile rubber. The processing aid is formed by compounding acrylate copolymers of different molecular weights, wherein the acrylate copolymers are ACR copolymers; the different molecular weights refer to high molecular weight, medium molecular weight, and low molecular weight, wherein the high molecular weight ACR copolymer is PA-40, the medium molecular weight ACR copolymer is PA-20, and the low molecular weight ACR copolymer is PA-101; wherein the compounded ACR copolymers are PA-40, PA-20, and PA-101 in a mass ratio of 2:2:1; or PA-40 and PA-101 in a mass ratio of 3:1; or PA-20 and PA-101 in a mass ratio of 3:

1. The average degree of polymerization of the PVC resin powder is 1800-2500; the plasticizer includes diisooctyl terephthalate, dioctyl adipate, or trioctyl trimellitate; the lubricant includes any one or more of oxidized polyethylene wax, stearic acid, and benzyl silicone oil. The solid raw materials include PVC resin powder, zinc stearate and calcium stearate as stabilizers, processing aids, oxidized polyethylene wax and stearic acid as lubricants, and PVC elastomer as elastomer; the liquid raw materials include plasticizers, epoxidized soybean oil, phenyl diisooctyl phosphite as stabilizers, chlorinated polyethylene and liquid nitrile rubber as elastomers, and benzyl silicone oil as lubricant.

2. The application of the high-elasticity and high-stability PVC granules prepared by the method of preparing high-elasticity and high-stability PVC granules as described in claim 1 in the preparation of medical catheter bodies or catheters.

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