A supercritical fluid injection molded foamed foam and method of making the same

Abstract

This invention discloses a supercritical fluid injection-molded foam material and its preparation method, relating to the field of polymer material processing technology. It is prepared from the following raw materials in parts by weight: 75-85 parts functional resin, 10-15 parts reinforcing fiber, 1-3 parts coupling agent, 0.8-1.2 parts antioxidant, 0.6-1 part lubricant, 2-4 parts plasticizer, 1-3 parts flame retardant, and 0.3-0.6 parts triethanolamine. The functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4''-bis(4-chlorophenyl sulfone)-1,1''-biphenyl. This foam material has a high cell density, small and uniform cell size, and excellent mechanical properties, flame retardancy, and heat resistance.

Description

Technical Field

[0001] This invention relates to the field of polymer material processing technology, and in particular to a supercritical fluid injection molding foam material and its preparation method. Background Technology

[0002] Polymer foam is a solid / gas composite material with excellent properties such as lightweight, high specific strength, large specific surface area, sound and heat insulation, and damping and vibration reduction. It has been widely used in industrial production and daily life. With technological advancements, the demand for polymer foam materials in defense, aerospace, shipbuilding, and rail transportation is increasing, and the performance requirements are becoming more stringent. Currently, most polymer foam materials on the market are prepared using chemical foaming methods, but this process has poor environmental friendliness. It is under these circumstances that supercritical fluid injection molding foaming technology has emerged, attracting widespread attention within the industry.

[0003] Supercritical fluid injection molding foaming technology is a novel physical foaming technology that uses supercritical fluid as a foaming agent. It involves rapidly depressurizing or rapidly heating a saturated supercritical fluid / polymer system to induce a thermodynamically unstable state, thereby inducing a large number of gas nuclei to simultaneously form a microporous structure within the polymer matrix. Rapid cooling then yields a high-porosity polymer foam material. This polymer foam material exhibits small cell size and high cell density, resulting in high specific strength and dimensional stability. However, existing supercritical fluid injection molding foam materials have relatively low cell density, large and uneven cell size, and their mechanical properties, flame retardancy, and heat resistance still require further improvement.

[0004] To address the aforementioned issues, Chinese invention patent CN111286070B discloses a supercritical fluid injection-molded polylactic acid (PLA) foam material and its preparation method. This invention utilizes bio-filler cellulose nanofibers to modify and prepare a lightweight, high-strength PLA foam material, improving its crystallinity and melt properties by using cellulose nanofibers as nucleating agents. The prepared cellulose nanofiber-modified PLA composite material is uniformly mixed with a supercritical fluid foaming agent in a microporous injection molding machine. Combined with an open-mold foaming device, microporous injection molding is performed to obtain a fully bio-based PLA foam material. This invention produces a microporous foamed cellulose nanofiber / PLA composite material with uniform cell size, high cell density, and excellent performance. The preparation method also boasts significant advantages such as high production efficiency, strong operability, stability, reliability, and ease of industrial production. However, its mechanical properties and heat resistance still require further improvement.

[0005] It is evident that developing a supercritical fluid injection molding foam material with high cell density, small and uniform cell size, and excellent mechanical properties, flame retardancy, and heat resistance, as well as its preparation method, meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of the supercritical fluid foaming technology field. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a supercritical fluid injection molding foam material with high cell density, small and uniform cell size, excellent mechanical properties, flame retardancy and heat resistance, and its preparation method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a supercritical fluid injection molding foam material, which is prepared from the following raw materials in parts by weight: 75-85 parts of functional resin, 10-15 parts of reinforcing fiber, 1-3 parts of coupling agent, 0.8-1.2 parts of antioxidant, 0.6-1 part of lubricant, 2-4 parts of plasticizer, 1-3 parts of flame retardant, and 0.3-0.6 parts of triethanolamine; wherein the functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl.

[0008] Preferably, the preparation method of the functional resin includes the following steps: 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene are mixed evenly and added to a reaction vessel equipped with a water separator. The air in the vessel is replaced with nitrogen. Under nitrogen protection, the mixture is stirred and reacted at 125-145°C for 3-5 hours. Water and toluene generated during the reaction are removed through the water separator. The temperature is then raised to 165-175°C, and the reaction is continued with stirring for 18-22 hours. The mixture is then cooled to room temperature and precipitated in water. The precipitated polymer is washed 3-6 times with ethanol and finally dried in a vacuum drying oven at 90-95°C to constant weight to obtain the functional resin.

[0009] Preferably, the molar ratio of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene is 1:1:(1-2):(15-25):8.

[0010] Preferably, the reinforcing fiber is at least one of alkali-free glass fiber, carbon fiber, and boron fiber.

[0011] Preferably, the reinforcing fibers have an average diameter of 3-7 μm and a length of 1-3 mm.

[0012] Preferably, the coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0013] Preferably, the antioxidant is at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

[0014] Preferably, the lubricant is at least one of pentaerythritol stearate, zinc stearate, and ethylene bis-stearamide.

[0015] Preferably, the plasticizer is epoxidized soybean oil.

[0016] Preferably, the flame retardant is H-WF-10 aluminum hydroxide flame retardant, provided by Zibo Hanjin New Material Technology Co., Ltd.

[0017] Another object of the present invention is to provide a method for preparing the supercritical fluid injection molding foam material, comprising the following steps: Step S1: Mix the raw materials evenly according to their mass proportions, add them to the injection molding machine barrel, adjust the process parameters of the injection molding machine, and plasticize them under the shearing force of the screw and the external heating of the heating coil. Step S2: Use a supercritical fluid control system to directly inject CO2 or N2 into the melt, inject it into the mold cavity at high pressure and high speed, with a pressure of 110-140MPa and an injection speed of 300-800mm / s. Step S3: Suddenly reduce the pressure in the mold cavity from 110-140MPa to normal pressure for 35-60s. This causes a large amount of supersaturated gas in the melt to separate out and release uniform, fine microporous foam. The supercritical fluid injection molded foam material is then obtained through injection molding.

[0018] Preferably, the process parameters in step S1 are: temperature: 275-295℃ for stage 1, 260-280℃ for stage 2, and 245-280℃ for stage 3; injection pressure: 120MPa for stage 1, 100MPa for stage 2, and 140MPa for stage 3.

[0019] Due to the application of the above technical solution, the present invention has the following beneficial effects: (1) The preparation method of supercritical fluid injection molding foam material disclosed in this invention is simple, easy to operate, low in cost, and highly repeatable. It has many advantages such as high efficiency, high output, low cost, green and pollution-free, and is suitable for continuous large-scale production. It has high promotion and application value.

[0020] (2) The supercritical fluid injection molding foam material disclosed in this invention is made from the following raw materials in parts by weight: 75-85 parts of functional resin, 10-15 parts of reinforcing fiber, 1-3 parts of coupling agent, 0.8-1.2 parts of antioxidant, 0.6-1 parts of lubricant, 2-4 parts of plasticizer, and 1-3 parts of flame retardant; the functional resin is made by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl. Through the mutual cooperation and synergistic effect of the raw materials, the product is endowed with excellent mechanical properties, flame retardancy and heat resistance; the functional resin structure simultaneously introduces cyanobenzothiazole, phenyl ether, phenyl sulfone and biphenyl structures, which, under the multiple effects of electronic effect, steric hindrance effect and conjugation effect, make the product have better mechanical properties, better flame retardancy and heat resistance, more stable cell structure and longer test life.

[0021] (3) The supercritical fluid injection molding foam material disclosed in this invention adopts supercritical fluid injection molding foaming technology. Through the reasonable selection of process parameters, the resulting foam material has a large cell density and small and uniform cell size. While reducing the weight of the product, it can also ensure the physical properties and surface quality of the product. By adding additives such as reinforcing fibers, coupling agents, antioxidants, lubricants, plasticizers, and flame retardants, not only can the functions of these additives be realized, but they can also work with other raw materials to establish more foaming points and increase the foaming ratio. Triethanolamine can improve the permeability of supercritical fluids and, when combined with other raw materials, can further improve the foaming capacity. Detailed Implementation

[0022] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art. Example 1

[0023] A supercritical fluid injection molding foam material is prepared from the following raw materials in parts by weight: 75 parts functional resin, 10 parts reinforcing fiber, 1 part coupling agent, 0.8 parts antioxidant, 0.6 parts lubricant, 2 parts plasticizer, 1 part flame retardant, and 0.3 parts triethanolamine; wherein the functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenylsulfone)-1,1'-biphenyl.

[0024] The preparation method of the functional resin includes the following steps: 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene are mixed evenly and added to a reaction vessel equipped with a water separator. The air inside the vessel is replaced with nitrogen. Under nitrogen protection, the mixture is stirred at 125°C for 3 hours. Water and toluene generated during the reaction are removed through the water separator. The temperature is then raised to 165°C, and the reaction is continued with stirring for 18 hours. The mixture is then cooled to room temperature, precipitated in water, and the precipitated polymer is washed three times with ethanol. Finally, it is dried in a vacuum drying oven at 90°C to constant weight to obtain the functional resin. The molar ratio of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene is 1:1:1:15:8. GPC testing shows that the functional resin has a molecular weight (M) of 100%. n =15720 g / mol, M W / M n =1.337; Elemental quantitative analysis and weight change calculations confirmed that the molar ratio of the structural units introduced by 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenylsulfone)-1,1'-biphenyl in this functional resin is the same as the theoretical value.

[0025] The reinforcing fiber is alkali-free glass fiber; the average diameter of the reinforcing fiber is 3μm and the length is 1mm; the coupling agent is silane coupling agent KH550; the antioxidant is antioxidant 1010; the lubricant is pentaerythritol stearate; the plasticizer is epoxidized soybean oil; and the flame retardant is H-WF-10 aluminum hydroxide flame retardant, provided by Zibo Hanjin New Material Technology Co., Ltd.

[0026] A method for preparing the supercritical fluid injection-molded foam material includes the following steps: Step S1: Mix the raw materials evenly according to their mass proportions, add them to the injection molding machine barrel, adjust the process parameters of the injection molding machine, and plasticize them under the shearing force of the screw and the external heating of the heating coil. Step S2: Use a supercritical fluid control system to directly inject CO2 into the melt, inject it into the mold cavity at high pressure and high speed, with a pressure of 110MPa and an injection speed of 300mm / s. Step S3: Suddenly reduce the pressure in the mold cavity from 110MPa to normal pressure for 35s. This causes a large amount of supersaturated gas in the melt to separate out and release uniform, fine microporous foam. The supercritical fluid injection molded foam material is then obtained through injection molding.

[0027] The process parameters mentioned in step S1 are as follows: temperature: 275℃ for stage 1, 260℃ for stage 2, and 245℃ for stage 3; injection pressure: 120MPa for stage 1, 100MPa for stage 2, and 140MPa for stage 3. Example 2

[0028] A supercritical fluid injection molding foam material is prepared from the following raw materials in parts by weight: 77 parts functional resin, 12 parts reinforcing fiber, 1.5 parts coupling agent, 0.9 parts antioxidant, 0.7 parts lubricant, 2.5 parts plasticizer, 1.5 parts flame retardant, and 0.4 parts triethanolamine; wherein the functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenylsulfone)-1,1'-biphenyl.

[0029] The preparation method of the functional resin includes the following steps: 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene are mixed evenly and then added to a reaction vessel equipped with a water separator. The air in the vessel is replaced with nitrogen. Under nitrogen protection, the mixture is stirred at 130°C for 3.5 hours. Water and toluene generated during the reaction are removed through the water separator. The temperature is then raised to 168°C and the reaction is continued to be stirred for 19 hours. The mixture is then cooled to room temperature and precipitated in water. The precipitated polymer is washed four times with ethanol and finally dried in a vacuum drying oven at 92°C to constant weight to obtain the functional resin.

[0030] The molar ratio of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene is 1:1:1.2:17:8; the reinforcing fiber is carbon fiber; the average diameter of the reinforcing fiber is 4 μm and the length is 1.5 mm; the coupling agent is silane coupling agent KH560; the antioxidant is antioxidant 168; the lubricant is zinc stearate; the plasticizer is epoxidized soybean oil; and the flame retardant is H-WF-10 aluminum hydroxide flame retardant, provided by Zibo Hanjin New Material Technology Co., Ltd.

[0031] A method for preparing the supercritical fluid injection-molded foam material includes the following steps: Step S1: Mix the raw materials evenly according to their mass proportions, add them to the injection molding machine barrel, adjust the process parameters of the injection molding machine, and plasticize them under the shearing force of the screw and the external heating of the heating coil. Step S2: Use a supercritical fluid control system to directly inject N2 into the melt, inject it into the mold cavity at high pressure and high speed, with a pressure of 120MPa and an injection speed of 400mm / s; Step S3: Suddenly reduce the pressure in the mold cavity from 120MPa to normal pressure for 40s. This causes a large amount of supersaturated gas in the melt to separate out and release uniform, fine microporous foam. The supercritical fluid injection molded foam material is then obtained through injection molding.

[0032] The process parameters mentioned in step S1 are as follows: temperature: 280℃ for stage 1, 265℃ for stage 2, and 250℃ for stage 3; injection pressure: 120MPa for stage 1, 100MPa for stage 2, and 140MPa for stage 3. Example 3

[0033] A supercritical fluid injection molding foam material is prepared from the following raw materials in parts by weight: 80 parts functional resin, 13 parts reinforcing fiber, 2 parts coupling agent, 1 part antioxidant, 0.8 parts lubricant, 3 parts plasticizer, 2 parts flame retardant, and 0.45 parts triethanolamine; wherein the functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenylsulfone)-1,1'-biphenyl.

[0034] The preparation method of the functional resin includes the following steps: 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene are mixed evenly and then added to a reaction vessel equipped with a water separator. The air in the vessel is replaced with nitrogen. Under nitrogen protection, the mixture is stirred at 135°C for 4 hours. Water and toluene generated during the reaction are removed through the water separator. The temperature is then raised to 170°C and the reaction is continued to be stirred for 20 hours. The mixture is then cooled to room temperature and precipitated in water. The precipitated polymer is washed five times with ethanol and finally dried in a vacuum drying oven at 93°C to constant weight to obtain the functional resin.

[0035] The molar ratio of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene is 1:1:1.5:20:8; the reinforcing fiber is boron fiber; the average diameter of the reinforcing fiber is 5 μm and the length is 2 mm; the coupling agent is silane coupling agent KH570; the antioxidant is antioxidant 1076; the lubricant is pentaerythritol stearate; the plasticizer is epoxidized soybean oil; and the flame retardant is H-WF-10 aluminum hydroxide flame retardant, provided by Zibo Hanjin New Material Technology Co., Ltd.

[0036] A method for preparing the supercritical fluid injection-molded foam material includes the following steps: Step S1: Mix the raw materials evenly according to their mass proportions, add them to the injection molding machine barrel, adjust the process parameters of the injection molding machine, and plasticize them under the shearing force of the screw and the external heating of the heating coil. Step S2: CO2 is directly injected into the melt using a supercritical fluid control system. The injection is carried out at high pressure and high speed into the mold cavity, with a pressure of 125 MPa and an injection speed of 550 mm / s. Step S3: Suddenly reduce the pressure in the mold cavity from 125MPa to normal pressure for 50s. This causes a large amount of supersaturated gas in the melt to separate out and release uniform, fine microporous foam. The supercritical fluid injection molded foam material is then obtained through injection molding.

[0037] The process parameters mentioned in step S1 are as follows: temperature: 285℃ for stage 1, 270℃ for stage 2, and 265℃ for stage 3; injection pressure: 120MPa for stage 1, 100MPa for stage 2, and 140MPa for stage 3. Example 4

[0038] A supercritical fluid injection molding foam material is prepared from the following raw materials in parts by weight: 83 parts functional resin, 14 parts reinforcing fiber, 2.5 parts coupling agent, 1.1 parts antioxidant, 0.9 parts lubricant, 3.5 parts plasticizer, 2.5 parts flame retardant, and 0.55 parts triethanolamine; wherein the functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenylsulfone)-1,1'-biphenyl.

[0039] Preferably, the preparation method of the functional resin includes the following steps: 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene are mixed evenly and then added to a reaction vessel equipped with a water separator. The air inside the vessel is replaced with nitrogen, and the reaction is carried out at 140°C for 4.5 hours under nitrogen protection. Water and toluene generated during the reaction are removed through the water separator. The temperature is then raised to 173°C, and the reaction is continued with stirring for 21 hours. The mixture is then cooled to room temperature and reacted in water. The precipitated polymer was washed five times with ethanol and then dried at 94°C in a vacuum drying oven to constant weight to obtain the functional resin. The molar ratio of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene was 1:1:1.8:23:8. The reinforcing fiber was a mixture of alkali-free glass fiber, carbon fiber, and boron fiber in a mass ratio of 1:2:1. The average diameter of the reinforcing fiber was 6 μm and the length was 2.5 mm.

[0040] The coupling agent is a mixture of silane coupling agents KH550, KH560, and KH570 in a mass ratio of 1:2:1; the antioxidant is a mixture of antioxidant 1010, antioxidant 168, and antioxidant 1076 in a mass ratio of 1:3:2; the lubricant is a mixture of pentaerythritol stearate, zinc stearate, and ethylene bis-stearamide in a mass ratio of 1:1:1; the plasticizer is epoxidized soybean oil; and the flame retardant is H-WF-10 aluminum hydroxide flame retardant, provided by Zibo Hanjin New Material Technology Co., Ltd.

[0041] A method for preparing the supercritical fluid injection-molded foam material includes the following steps: Step S1: Mix the raw materials evenly according to their mass proportions, add them to the injection molding machine barrel, adjust the process parameters of the injection molding machine, and plasticize them under the shearing force of the screw and the external heating of the heating coil. Step S2: Use a supercritical fluid control system to directly inject N2 into the melt, inject it into the mold cavity at high pressure and high speed, with a pressure of 135MPa and an injection speed of 700mm / s; Step S3: Suddenly reduce the pressure in the mold cavity from 135MPa to normal pressure for 55s. This causes a large amount of supersaturated gas in the melt to separate out and release uniform, fine microporous foam. The supercritical fluid injection molded foam material is then obtained through injection molding.

[0042] The process parameters mentioned in step S1 are as follows: temperature: 290℃ for stage 1, 275℃ for stage 2, and 280℃ for stage 3; injection pressure: 120MPa for stage 1, 100MPa for stage 2, and 140MPa for stage 3. Example 5

[0043] A supercritical fluid injection molding foam material is prepared from the following raw materials in parts by weight: 85 parts functional resin, 15 parts reinforcing fiber, 3 parts coupling agent, 1.2 parts antioxidant, 1 part lubricant, 4 parts plasticizer, 3 parts flame retardant, and 0.6 parts triethanolamine; wherein the functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl.

[0044] The preparation method of the functional resin includes the following steps: 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene are mixed evenly and then added to a reaction vessel equipped with a water separator. The air in the vessel is replaced with nitrogen. Under nitrogen protection, the mixture is stirred at 145°C for 5 hours. Water and toluene generated during the reaction are removed through the water separator. The temperature is then raised to 175°C and the reaction is continued to be stirred for 22 hours. The mixture is then cooled to room temperature and precipitated in water. The precipitated polymer is washed 6 times with ethanol and finally dried in a vacuum drying oven at 95°C to constant weight to obtain the functional resin.

[0045] The molar ratio of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene is 1:1:2:25:8; the reinforcing fiber is alkali-free glass fiber; the average diameter of the reinforcing fiber is 7 μm and the length is 3 mm; the coupling agent is silane coupling agent KH560; the antioxidant is antioxidant 168; the lubricant is ethylene bis-stearamide; the plasticizer is epoxidized soybean oil; and the flame retardant is H-WF-10 aluminum hydroxide flame retardant, provided by Zibo Hanjin New Material Technology Co., Ltd.

[0046] A method for preparing the supercritical fluid injection-molded foam material includes the following steps: Step S1: Mix the raw materials evenly according to their mass proportions, add them to the injection molding machine barrel, adjust the process parameters of the injection molding machine, and plasticize them under the shearing force of the screw and the external heating of the heating coil. Step S2: CO2 is directly injected into the melt using a supercritical fluid control system. The injection is carried out under high pressure and high speed into the mold cavity. The pressure is 140 MPa and the injection speed is 800 mm / s. Step S3: Suddenly reduce the pressure in the mold cavity from 140MPa to normal pressure for 60s. This causes a large amount of supersaturated gas in the melt to separate out and release uniform, fine microporous foam. The supercritical fluid injection molded foam material is then obtained through injection molding.

[0047] The process parameters mentioned in step S1 are as follows: temperature: 295℃ for stage 1, 280℃ for stage 2, and 280℃ for stage 3; injection pressure: 120MPa for stage 1, 100MPa for stage 2, and 140MPa for stage 3.

[0048] Comparative Example 1 A supercritical fluid injection molding foam material and its preparation method are basically the same as those in Example 1, except that 4,6-hydroxy-2-cyanobenzothiazole is replaced with an equimolar amount of bisphenol A.

[0049] Comparative Example 2 A supercritical fluid injection molding foam material and its preparation method are basically the same as those in Example 1, except that 4,4'-dichlorodiphenyl sulfone is used instead of 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, and triethanolamine is not added.

[0050] To further illustrate the beneficial technical effects of the supercritical fluid injection-molded foam materials involved in the various embodiments of the present invention, relevant performance tests were conducted on the supercritical fluid injection-molded foam materials involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1, and the test methods are as follows: (1) Cell diameter and cell density: The foamed material was quenched with liquid nitrogen and the cross-section was sprayed with gold. The cell structure inside the foamed material was observed by scanning electron microscope (SEM). The cell size was measured by ImageJ software and the cell density was calculated. (2) Tensile strength: Refer to GB / T 9641-1988; (3) Flame retardancy: Flame retardancy is classified according to UL-94; (4) Heat resistance stability: Each foam material was placed in a forced-air drying oven at 150°C for 100 hours. After cooling to room temperature, the tensile strength was tested again by referring to the method in (2). The tensile strength retention rate was statistically analyzed and calculated. The larger the value, the better the heat resistance performance.

[0051] Table 1 As can be seen from Table 1, the supercritical fluid injection molding foam material involved in the embodiments of the present invention has higher mechanical properties, flame retardant properties and heat resistance than the comparative example, with higher cell density and smaller cell size; the combined use of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl and triethanolamine is beneficial to improving the above properties.

[0052] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A supercritical fluid injection molding foam material, characterized in that, It is prepared from the following raw materials in parts by weight: 75-85 parts of functional resin, 10-15 parts of reinforcing fiber, 1-3 parts of coupling agent, 0.8-1.2 parts of antioxidant, 0.6-1 part of lubricant, 2-4 parts of plasticizer, 1-3 parts of flame retardant, and 0.3-0.6 parts of triethanolamine; wherein the functional resin is prepared by polycondensation reaction of 4,6-hydroxy-2-cyanobenzothiazole and 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl.

2. The supercritical fluid injection-molded foam material according to claim 1, characterized in that, The preparation method of the functional resin includes the following steps: 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene are mixed evenly and then added to a reaction vessel equipped with a water separator. The air in the vessel is replaced with nitrogen. Under nitrogen protection, the mixture is stirred and reacted at 125-145°C for 3-5 hours. Water and toluene generated during the reaction are removed through the water separator. The temperature is then raised to 165-175°C, and the reaction is continued with stirring for 18-22 hours. The mixture is then cooled to room temperature and precipitated in water. The precipitated polymer is washed 3-6 times with ethanol and finally dried in a vacuum drying oven at 90-95°C to constant weight to obtain the functional resin.

3. The supercritical fluid injection-molded foam material according to claim 2, characterized in that, The molar ratio of 4,6-hydroxy-2-cyanobenzothiazole, 4,4'-bis(4-chlorophenyl sulfone)-1,1'-biphenyl, cesium carbonate, dimethyl sulfoxide, and toluene is 1:1:(1-2):(15-25):

8.

4. The supercritical fluid injection-molded foam material according to claim 1, characterized in that, The reinforcing fiber is at least one of alkali-free glass fiber, carbon fiber, and boron fiber; the average diameter of the reinforcing fiber is 3-7 μm and the length is 1-3 mm.

5. The supercritical fluid injection-molded foam material according to claim 1, characterized in that, The coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570; the antioxidant is at least one of antioxidant 1010, antioxidant 168, and antioxidant 1076.

6. The supercritical fluid injection-molded foam material according to claim 1, characterized in that, The lubricant is at least one of pentaerythritol stearate, zinc stearate, and ethylene bis-stearamide; the plasticizer is epoxidized soybean oil.

7. The supercritical fluid injection-molded foam material according to claim 1, characterized in that, The flame retardant is H-WF-10 aluminum hydroxide flame retardant.

8. A method for preparing a supercritical fluid injection-molded foam material according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Mix the raw materials evenly according to their mass proportions, add them to the injection molding machine barrel, adjust the process parameters of the injection molding machine, and plasticize them under the action of screw shearing force and external heating of the heating coil. Step S2: Use a supercritical fluid control system to directly inject CO2 or N2 into the melt, inject it into the mold cavity at high pressure and high speed, with a pressure of 110-140MPa and an injection speed of 300-800mm / s; Step S3: Suddenly reduce the pressure in the mold cavity from 110-140MPa to normal pressure for 35-60s. This causes a large amount of supersaturated gas in the melt to separate out and release uniform, fine microporous foam. The supercritical fluid injection molded foam material is then obtained through injection molding.

9. The method for preparing supercritical fluid injection-molded foam material according to claim 8, characterized in that, The process parameters mentioned in step S1 are as follows: temperature: 275-295℃ for stage 1, 260-280℃ for stage 2, and 245-280℃ for stage 3; injection pressure: 120MPa for stage 1, 100MPa for stage 2, and 140MPa for stage 3.

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