High-cold-resistance plastic particles and production process thereof

Abstract

The invention relates to the technical field of plastics, and provides high cold-resistant plastic particles and a production process thereof, the high cold-resistant plastic particles comprise the following components by weight: 95-105 parts of polyether thermoplastic polyurethane, 15-35 parts of hydrogenated butadiene-acrylonitrile rubber, 4-6 parts of maleic anhydride grafted hydrogenated SEBS, 1.5-2.5 parts of polycarbodiimide, and 0.4-0.6 part of an antioxidant. 8-12 parts by weight of barium sulfate treated by a silane coupling agent, 0.8-1.3 parts by weight of a lubricant and 1-2 parts by weight of an auxiliary agent. The invention solves the problem that the existing plastic particles for pipes cannot simultaneously have the properties of acid and alkali resistance, cold resistance and bending resistance.

Description

Technical Field

[0001] This invention relates to the field of plastics technology, specifically to a high cold-resistant plastic particle and its production process. Background Technology

[0002] Plastics are polymeric compounds formed by polymerization of monomers through addition or condensation reactions. They possess moderate resistance to deformation, falling between fibers and rubber. They are composed of synthetic resins and additives such as fillers, plasticizers, stabilizers, lubricants, and colorants. The main component of plastics is resin. Resin refers to the polymeric compound before it is mixed with various additives. The term "resin" originally came from lipids secreted by plants and animals, such as rosin and shellac. The basic properties of plastics are primarily determined by the nature of the resin, but additives also play a crucial role. Different properties of plastics determine their applications in daily life and industry. With technological advancements, research on plastic modification has never ceased. It is hoped that in the near future, modified plastics will have wider applications, even replacing materials like steel and eliminating environmental pollution.

[0003] Plastics are made from plastic particles. There are many types of plastic particles: recycled PP, recycled PE, polystyrene, polyvinyl chloride, ABS, nylon, and so on.

[0004] Plastic pipes are widely used in our building decoration, and they need to withstand various environments during use. Currently, the plastic particles used for pipes cannot simultaneously possess the properties of acid and alkali resistance, cold resistance, and bending resistance; these properties still need improvement. A type of plastic particle that can simultaneously possess these properties is needed to produce pipes. Summary of the Invention

[0005] To address the limitation that existing tubular plastic particles cannot simultaneously possess properties such as acid and alkali resistance, cold resistance, and flexural strength, this invention provides a high-cold-resistant plastic particle and its production process. The plastic particles produced by this invention are not difficult to manufacture and possess both high cold resistance and excellent acid and alkali resistance and flexural strength.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high cold-resistant plastic particle, comprising the following components in parts by weight: 95-105 parts by weight of polyether-type thermoplastic polyurethane, 15-35 parts by weight of hydrogenated nitrile rubber, 4-6 parts by weight of maleic anhydride-grafted hydrogenated SEBS, 1.5-2.5 parts by weight of polycarbodiimide, 0.4-0.6 parts by weight of antioxidant, 8-12 parts by weight of barium sulfate treated with silane coupling agent, 0.8-1.3 parts by weight of lubricant, and 1-2 parts by weight of additives.

[0007] Furthermore, the lubricant is ethylene bis-stearamide.

[0008] Furthermore, the antioxidants include antioxidant 1010 and antioxidant 168 configured in a 1:1 ratio.

[0009] Furthermore, the additive is a hydrogenated styrene-butadiene block copolymer.

[0010] The preparation process of the above-mentioned high cold-resistant plastic particles includes the following steps:

[0011] Step 1, material pretreatment: First, dry the polyether thermoplastic polyurethane and hydrogenated nitrile rubber in an 80℃ forced-air oven for 4 hours. Then, add the dried polyether thermoplastic polyurethane, hydrogenated nitrile rubber, maleic anhydride-grafted hydrogenated SEBS, barium sulfate treated with silane coupling agent, antioxidant, lubricant and additives into a high-speed mixer and mix at 800-1000 rpm for 5-7 minutes to ensure that all components are fully and evenly mixed.

[0012] Step 2: The mixture obtained in Step 1 is fed into a co-rotating twin-screw extruder for melt blending and extrusion. Specifically, the mixture obtained in Step 1 is added from the main feed port. Liquid hydrolytic stabilizer polycarbodiimide is injected into the melt section of the co-rotating twin-screw extruder through a precision liquid injection pump. Vacuum exhaust is turned on before the homogenization zone of the co-rotating twin-screw extruder, and the overall melt mixing temperature of the co-rotating twin-screw extruder is set to be less than 195°C.

[0013] Step 3, Cooling and Packaging: The strip extruded from the co-rotating twin-screw extruder in Step 2 is cooled in a water tank, dried by the air knife of a high-pressure air knife dryer, and then sent to a pelletizer to obtain finished high-cold-resistant plastic particles. The finished high-cold-resistant plastic particles are packaged in moisture-proof aluminum foil bags.

[0014] Furthermore, in step two, the temperature gradient of the co-rotating twin-screw extruder is as follows: feeding zone → 160℃, melting zone → 185-190℃, mixing zone → 190℃, homogenization zone → 185℃, and die head → 180℃.

[0015] Furthermore, in step three, the water temperature in the water tank is 20-25℃.

[0016] By adopting the aforementioned technical solution, the beneficial effects of this invention are as follows: This invention uses polyether-type thermoplastic polyurethane (TPU) as the matrix and introduces hydrogenated nitrile butadiene rubber (HNBR) as the second-phase elastomer. By grafting hydrogenated SEBS with maleic anhydride as a compatibilizer, the hydrogenated nitrile butadiene rubber (HNBR) is blended with the polyether-type thermoplastic polyurethane, forming dispersed "micro-islands" in the continuous phase of the polyether-type thermoplastic polyurethane. This greatly improves the impact strength and resistance to repeated bending of the composite material at low temperatures. Simultaneously, the addition of polycarbodiimide (PCDI) as a highly efficient hydrolysis stabilizer allows PCDI to preferentially react with the carboxyl groups generated during hydrolysis, terminating the autocatalytic hydrolysis process. This fundamentally and significantly improves the long-term stability of the polyether-type thermoplastic polyurethane under acidic, alkaline, and humid heat environments, enabling the polyether-type thermoplastic polyurethane to resist strong acids and alkalis. Therefore, this invention achieves superior performance in the polyether-type thermoplastic polyurethane... The product, achieved through a blend of plastic polyurethane and hydrogenated nitrile butadiene rubber (HNBR) grafted with maleic anhydride and hydrogenated SEBS, combined with a highly efficient hydrolytic stabilizer of polycarbodiimide, exhibits high cold resistance while also possessing excellent acid and alkali resistance and flexural strength. This allows the material to be widely used in high-end applications such as cold-resistant and oil-resistant pipe fittings for automotive engine compartments, corrosion-resistant bellows for industrial robots, seals for marine engineering equipment, and cable sheaths in extreme environments. Furthermore, the polycarbodiimide and antioxidants form a synergistic stabilizing system. Barium sulfate (BaSO4) treated with a silane coupling agent is used as a filler. Due to BaSO4's chemical inertness and acid and alkali resistance, it provides good dispersibility and dimensional stability. In particular, the silane coupling agent-treated barium sulfate exhibits better compatibility with the polymer and minimal impact on flexural strength, uniformly dispersing in the matrix and bearing some stress without introducing chemical weaknesses. Its compounded lubricant ensures smoother processing. Ethylene bis-stearamide, as a lubricant, improves processing fluidity, facilitates demolding, and reduces internal friction. The combined antioxidants 1010 and 168 prevent thermal oxidative degradation, protecting the polymer backbone from damage during processing and use. Hydrogenated styrene-butadiene block copolymers, as an additive, promote plasticization, reduce melt viscosity, and improve dispersibility.

[0017] During the production process, the overall melt mixing temperature of the co-rotating twin-screw extruder is set to less than 195°C to prevent the degradation of polyether-type thermoplastic polyurethane and hydrogenated nitrile rubber. Vacuum exhaust is opened before the homogenization zone of the co-rotating twin-screw extruder to remove possible moisture and low-molecular-weight volatiles. The production process of this invention adopts the most common twin-screw extrusion technology, requires no special equipment, has a mature and reliable process, and can be mass-produced. Detailed Implementation

[0018] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The raw materials, trade names, and equipment models used in the examples are shown in the table below:

[0020]

[0021] Test parameters and metrics:

[0022] Cold resistance: Tested according to GB / T 5470-2008 standard, the embrittlement temperature was determined by the low-temperature embrittlement impact test method for plastics;

[0023] Acid and alkali resistance: Tested according to GB / T 11547-2008 standard, the resistance of plastic to liquid chemical reagents was determined. Test conditions: after immersion in 10% H2SO4 and 10% NaOH solution at 70℃ for 72 hours, the tensile strength retention rate and mass change rate were measured.

[0024] Flexural strength: Tested according to GB / T 13934-2006 standard, using vulcanized rubber or thermoplastic rubber flexural cracking as the tester, and the crack grade or number of complete fractures is recorded using a Demosia type tester.

[0025] Mechanical properties: Tested according to the standard GB / T 1040.2-2022, using the tensile properties of plastics as the test.

[0026] Hardness: Tested according to GB / T 531.1-2008 standard, hardness was determined by Shore hardness tester method.

[0027] Example 1

[0028] High cold-resistant plastic particles, comprising the following components in parts by weight: 100 parts by weight of polyether thermoplastic polyurethane, 15 parts by weight of hydrogenated nitrile butadiene rubber, 4 parts by weight of maleic anhydride-grafted hydrogenated SEBS, 1.5 parts by weight of polycarbodiimide, 0.5 parts by weight of antioxidant, 10 parts by weight of barium sulfate treated with silane coupling agent, 1 part by weight of ethylene bis-stearamide, and 1 part by weight of hydrogenated styrene-butadiene block copolymer.

[0029] The silane coupling agent-treated barium sulfate was prepared as follows: a modified solution was prepared by mixing silane coupling agent (A174) with a mixed solvent (ethanol + water) in a mass ratio of 1:8:1, the pH was adjusted to 4, and hydrolysis was carried out for 30 minutes; then, 2% of the mass of the modified agent barium sulfate powder was added to the modified solution and stirred at 80°C for 1 hour; after filtration and washing, it was dried at 80°C for 4 hours to obtain silane coupling agent-treated barium sulfate.

[0030] The preparation process of the above-mentioned high cold-resistant plastic particles includes the following steps:

[0031] Step 1, material pretreatment: First, dry the polyether thermoplastic polyurethane and hydrogenated nitrile rubber in an 80℃ forced-air oven for 4 hours. Then, add the dried polyether thermoplastic polyurethane, hydrogenated nitrile rubber, maleic anhydride-grafted hydrogenated SEBS, barium sulfate treated with silane coupling agent, antioxidant, lubricant and additives into a high-speed mixer and mix at 800-1000 rpm for 5-7 minutes to ensure that all components are fully and evenly mixed.

[0032] Step 2: The mixture obtained in Step 1 is fed into a co-rotating twin-screw extruder for melt blending and extrusion. Specifically, the mixture obtained in Step 1 is added from the main feed port. Liquid hydrolyzed stabilizer polycarbodiimide is injected into the melt section of the co-rotating twin-screw extruder through a precision liquid injection pump. Vacuum exhaust is turned on before the homogenization zone of the co-rotating twin-screw extruder. The overall melt mixing temperature of the co-rotating twin-screw extruder is set to be less than 195℃. The temperature gradient of the co-rotating twin-screw extruder is as follows: feed zone → 160℃, melt zone → 185-190℃, mixing zone → 190℃, homogenization zone → 185℃, die head → 180℃.

[0033] Step 3, Cooling and Packaging: The strips extruded by the co-rotating twin-screw extruder in Step 2 are cooled in a water tank at a temperature of 20-25°C. The strips are then dried by the air knives of a high-pressure air knife dryer and fed into a pelletizer to obtain high-cold-resistant plastic particles. The high-cold-resistant plastic particles are then packaged in moisture-proof aluminum foil bags.

[0034] Product performance test results:

[0035] Embrittlement temperature (°C): ≤-60°C;

[0036] Strength retention rate after acid resistance: 88%;

[0037] Strength retention rate after alkali resistance: 90%;

[0038] Acid / alkali resistance mass change rate: <+1.5%;

[0039] Flexion cracking (times): >200,000;

[0040] Tensile strength (MPa): 28;

[0041] Elongation at break (%): 500%;

[0042] Hardness (Shore A): 90.

[0043] Example 2

[0044] High cold-resistant plastic particles, comprising the following components in parts by weight: 100 parts by weight of polyether-type thermoplastic polyurethane, 25 parts by weight of hydrogenated nitrile butadiene rubber, 5 parts by weight of maleic anhydride-grafted hydrogenated SEBS, 2 parts by weight of polycarbodiimide, 0.5 parts by weight of antioxidant, 10 parts by weight of barium sulfate treated with silane coupling agent, 1 part by weight of ethylene bis-stearamide, and 1.5 parts by weight of hydrogenated styrene-butadiene block copolymer.

[0045] The preparation process is the same as in Example 1.

[0046] Product performance test results:

[0047] Embrittlement temperature (°C): ≤-65°C;

[0048] Strength retention rate after acid resistance: 91%;

[0049] Strength retention rate after alkali resistance: 92%;

[0050] Acid / alkali resistance mass change rate: <+1.2%;

[0051] Flexion cracking (times): >400,000;

[0052] Tensile strength (MPa): 26;

[0053] Elongation at break (%): 550%;

[0054] Hardness (Shore A): 88.

[0055] Example 3

[0056] High cold-resistant plastic particles, comprising the following components in parts by weight: 100 parts by weight of polyether-type thermoplastic polyurethane, 25 parts by weight of hydrogenated nitrile butadiene rubber, 5 parts by weight of maleic anhydride-grafted hydrogenated SEBS, 2 parts by weight of polycarbodiimide, 0.5 parts by weight of antioxidant, 10 parts by weight of barium sulfate treated with silane coupling agent, 1 part by weight of ethylene bis-stearamide, and 1.5 parts by weight of hydrogenated styrene-butadiene block copolymer.

[0057] The preparation process is the same as in Example 1.

[0058] Product performance test results:

[0059] Embrittlement temperature (°C): ≤-68°C;

[0060] Strength retention rate after acid resistance: 93%;

[0061] Strength retention rate after alkali resistance: 94%;

[0062] Acid / alkali resistance mass change rate: <+1.0%;

[0063] Flexion cracking (times): >600,000

[0064] Tensile strength (MPa): 24;

[0065] Elongation at break (%): 600%;

[0066] Hardness (Shore A): 86.

[0067] Comparative Example 1

[0068] Plastic particles, comprising the following components in parts by weight: 100 parts by weight of polyether thermoplastic polyurethane, 0.6 parts by weight of antioxidant, 10 parts by weight of barium sulfate treated with silane coupling agent, 1 part by weight of ethylene bis-stearamide, and 1.5 parts by weight of hydrogenated styrene-butadiene block copolymer.

[0069] The preparation process is the same as in Example 1.

[0070] Product performance test results:

[0071] Embrittlement temperature (°C): ≤-45°C;

[0072] Strength retention rate after acid resistance: 65%;

[0073] Strength retention rate after alkali resistance: 70%;

[0074] Acid / alkali resistance mass change rate: +3.0%;

[0075] Flexion cracking (times): >50,000;

[0076] Tensile strength (MPa): 35;

[0077] Elongation at break (%): 450%;

[0078] Hardness (Shore A): 95.

[0079] Comparative Example 2

[0080] Plastic particles, high cold-resistant plastic particles, comprising the following components in parts by weight: 100 parts by weight of polyether thermoplastic polyurethane, 25 parts by weight of hydrogenated nitrile rubber, 5 parts by weight of maleic anhydride-grafted hydrogenated SEBS, 0.5 parts by weight of antioxidant, 10 parts by weight of barium sulfate treated with silane coupling agent, 1 part by weight of ethylene bis-stearamide, and 1.5 parts by weight of hydrogenated styrene-butadiene block copolymer.

[0081] The preparation process is the same as in Example 1.

[0082] Product performance test results:

[0083] Embrittlement temperature (°C): ≤-65°C;

[0084] Strength retention rate after acid resistance: 52% (severe degradation);

[0085] Strength retention rate after alkali resistance: 58% (severe degradation);

[0086] Acid / alkali resistance mass change rate: +8.0% (swelling);

[0087] Flexion cracking (times): >400,000;

[0088] Tensile strength (MPa): 25;

[0089] Elongation at break (%): 540%;

[0090] Hardness (Shore A): 87.

[0091] Based on the final measured values ​​of the three examples: The increase in hydrogenated nitrile butadiene rubber (HNBR) content dramatically improved the material's cold resistance and flexural strength. Although the tensile strength decreased slightly, the overall performance achieved an optimal balance. Most importantly, thanks to the addition of polycarbodiimide (PCDI), the mechanical properties retained an extremely high rate (>90%) after harsh acid and alkali aging, far superior to the comparative example, demonstrating its unparalleled chemical stability. Comparative Example 1: Although pure polyether TPU has some hydrolysis resistance, its performance deteriorates severely under high temperature and strong acid / alkali conditions, and its cold resistance and flexural strength are only average. Comparative Example 2: Although hydrogenated nitrile butadiene rubber (HNBR) was added, its cold resistance and flexural strength were comparable to the examples. However, due to the lack of the hydrolysis stabilizer PCDI, it underwent severe hydrolytic degradation in acidic and alkaline environments, resulting in extremely low strength retention, demonstrating the decisive role of PCDI in the chemical resistance of this system.

[0092] The specific weight ratio of each raw material in this invention is preferably as follows: 95-105 parts by weight of polyether-type thermoplastic polyurethane, 15-35 parts by weight of hydrogenated nitrile rubber, 4-6 parts by weight of maleic anhydride-grafted hydrogenated SEBS, 1.5-2.5 parts by weight of polycarbodiimide, 0.4-0.6 parts by weight of antioxidant, 8-12 parts by weight of barium sulfate treated with silane coupling agent, 0.8-1.3 parts by weight of lubricant, 1-2 parts by weight of additives, and antioxidants are antioxidant 1010 and antioxidant 168 mixed in a 1:1 ratio.

[0093] Lubricants can also be material replacements, other than ethylene bis-stearamide, that can achieve the same function of improving processing flowability and facilitating demolding. Additives can also be polyolefin processing aids, other than hydrogenated styrene-butadiene block copolymers, that can achieve the same function of promoting plasticization, reducing melt viscosity, and improving dispersibility.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A highly cold-resistant plastic particle, characterized by: The components include the following weight parts: polyether type thermoplastic polyurethane 95-105 parts by weight, hydrogenated nitrile rubber 15-35 parts by weight, maleic anhydride grafted hydrogenated SEBS 4-6 parts by weight, polycarbodiimide 1.5-2.5 parts by weight, antioxidant 0.4-0.6 parts by weight, silane coupling agent treated barium sulfate 8-12 parts by weight, lubricant 0.8-1.3 parts by weight, and auxiliary 1-2 parts by weight.

2. The highly cold-resistant plastic particles according to claim 1, characterized in that: The lubricant is ethylene bis-stearamide.

3. The highly cold-resistant plastic particles according to claim 1, characterized in that: The antioxidant includes 1:1 configuration of antioxidant 1010 and antioxidant 168.

4. The highly cold-resistant plastic particles according to claim 1, characterized in that: The auxiliary is hydrogenated styrene-butadiene block copolymer.

5. The process for the preparation of the highly cold-resistant plastic particles according to any one of the preceding claims 1 to 4, characterized in that: The method includes the following steps: Step one, material pretreatment, first dry the polyether type thermoplastic polyurethane and hydrogenated nitrile rubber in the 80℃ air oven for 4 hours, then add the dried polyether type thermoplastic polyurethane, hydrogenated nitrile rubber, maleic anhydride grafted hydrogenated SEBS, silane coupling agent treated barium sulfate, antioxidant, lubricant and auxiliary into a high-speed mixer, mix at 800-1000 rpm for 5-7 minutes, so that the components are fully mixed and uniform; Step two, melt blend the mixture obtained in step one by feeding it into a co-rotating twin screw extruder, i.e. the mixture obtained in step one is fed from the main feeding port, the liquid hydrolysis stabilizer polycarbodiimide is injected through a precision liquid injection pump at the middle of the melt section of the co-rotating twin screw extruder, the vacuum exhaust is opened before the homogenization zone of the co-rotating twin screw extruder, and the overall melt mixing temperature of the co-rotating twin screw extruder is set to less than 195℃, Step three, cooling and packaging: cool the strip material extruded from the co-rotating twin screw extruder in a water tank, then blow dry it by a high-pressure air knife dryer, send it into a pelletizer to be pelletized, obtain finished high cold-resistant plastic particles, and package the finished high cold-resistant plastic particles in moisture-proof aluminum foil bags.

6. The process for the preparation of highly cold-resistant plastic particles according to claim 5, characterized in that: The temperature gradient of the co-rotating twin screw extruder in step two is: feeding zone→160℃, melt zone→185-190℃, mixing zone→190℃, homogenization zone→185℃, and die head→180℃.

7. The process for the preparation of highly cold-resistant plastic particles according to claim 5, characterized in that: The water temperature of the water tank in step three is 20-25℃.

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