Hard chlorinated polyvinyl chloride foam material and preparation method thereof

Abstract

The invention provides a hard chlorinated polyvinyl chloride foam material and a preparation method thereof, and relates to the field of chlorinated polyvinyl chloride. The preparation method of the hard chlorinated polyvinyl chloride foaming material comprises the following steps: preparing a composite foaming system, performing segmented premixing, preparing a material blank, and performing foaming molding. According to the preparation method of the hard chlorinated polyvinyl chloride foam material, the material temperature in the foaming preparation process of the CPVC material can be effectively reduced, the problems of yellowing and embrittlement of the processed CPVC material can be avoided, the appearance of a CPVC foamed product can be improved, the situations of non-uniform bubble hole size, hole stringing and hole breaking caused by decomposition of CPVC are reduced, the impact resistance of the CPVC material is improved, and the service life of the CPVC material is prolonged. The rigidity of the CPVC material is improved, and the deformation problem of the CPVC material is improved.

Description

Technical Field

[0001] The invention relates to the field of chlorinated polyvinyl chloride, in particular to a rigid chlorinated polyvinyl chloride foam material and a preparation method thereof. Background Art

[0002] Rigid flame-retardant foam materials are used in the fields of locomotive ceilings, interior decoration panels, building exterior wall panels, interior decoration panels, advertisements, exhibition panels, cold storage and special cold-insulation engineering panels, environmental protection templates, etc. They require good strength, lightness, not easy to deform, and have sound insulation, heat insulation, thermal insulation, flame retardancy, moisture resistance, and mildew resistance. Common polymer materials for foam panels include polystyrene, polyurethane, polypropylene, etc. These materials have the characteristics of light weight, good heat insulation, excellent sound insulation, sound absorption, filtration, and thermal insulation, but poor flame retardancy and flammability make them have strong fire hazards and self-reinforcing combustion performance in the event of a fire. The flame retardancy of the material can be improved by adding flame retardants, but it will lead to a decrease in the physical properties of the material, a significant increase in processing difficulty, an increase in cost, and limited use.

[0003] Chlorinated polyvinyl chloride (CPVC) is a material obtained by chlorination of PVC, with a chlorine content between 60-72wt%. The increase in chlorine content gives CPVC a series of excellent properties. CPVC has low thermal conductivity, good thermal insulation and heat preservation effects; good flame retardant and smoke suppression properties; high heat deformation temperature, good heat resistance; strong affinity, easy to print, and is an ideal substrate for flame retardant foaming materials. However, CPVC has a high viscosity, which can easily lead to a low foaming ratio; and it is difficult to control the size and uniformity of the cells. In addition, CPVC materials have poor thermal stability during processing and are prone to yellowing. Especially in the processing of foamed products, as the organic foaming agent decomposes and releases heat, the melt temperature will continue to be at a high temperature, causing the product to turn yellow and brittle, affecting the performance of the final product. In decorative applications, it has a serious impact on the appearance and the use effect is significantly reduced.

[0004] The prior art discloses a method of preparing CPVC by compounding a high-temperature foaming agent such as azodicarbonamide with a low-temperature foaming agent such as 4,4-di-sulfonylhydrazine diphenyl ether, or directly using a single foaming agent; and in this process, the yellowing problem of CPVC is improved by increasing the amount of stabilizer added. However, the solid stabilizer used will make the processing of CPVC materials difficult and reduce the physical properties of the material; although the liquid stabilizer has good processing performance, when it is added in a large amount, it has an adverse effect on the hardness of the rigid CPVC material, and the material deformability becomes larger; and there are defects such as high production cost and poor economy. In addition, the inventor has found through research that the prior art generally improves the non-foaming system in order to improve the adverse effect of the foaming agent on the CPVC material during the foaming process; the stabilizer added in the preparation of CPVC material itself cannot solve the many problems caused by the decomposition and exothermic release of the existing mainstream foaming agent, and there is still the problem of serious yellowing of the material caused by the exothermic release of the foaming agent, and the CPVC material still has problems such as poor cell size and cell uniformity, low notch impact strength and easy deformation.

[0005] In response to the above problems, the inventors have further studied and found that during the use of high-temperature foaming agent azodicarbonamide and low-temperature foaming agent, due to the large difference in the decomposition temperatures of the two auxiliary agents, the high-temperature foaming agent azodicarbonamide has not yet begun to decompose, while the low-temperature foaming agent has been mostly decomposed. The decomposition temperature matching performance of the two is poor, which directly leads to the inability of the two foaming agents to effectively cooperate, and thus the inability to effectively improve the above-mentioned defects. Summary of the invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a rigid chlorinated polyvinyl chloride foam material and a preparation method thereof, which can effectively reduce the material temperature in the foaming preparation process of the CPVC material, avoid the yellowing and brittleness problems of the CPVC material after processing, improve the appearance of the CPVC foamed product, reduce the occurrence of uneven foaming hole size, string holes and broken holes caused by the decomposition of CPVC, improve the impact resistance of the CPVC material, improve the rigidity of the CPVC material, and improve the deformation problem of the CPVC material.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a rigid chlorinated polyvinyl chloride foam material, characterized in that it comprises the following steps: preparing a composite foaming system, premixing in stages, preparing a material embryo, and foaming and molding; The preparation of the composite foaming system comprises the following steps: preparing a first foaming system, preparing a second foaming system; The method for preparing the first foaming system comprises: adding azodicarbonamide, a main foaming agent, into a mixed solvent, heating to 60-75° C. to dissolve, adding zinc oxide, stirring, cooling to below 35° C., and filtering to obtain a solid substance; mixing the solid substance at a temperature of 85-95° C., heating to 120-135° C., mixing the solid substance and zinc stearate uniformly, and cooling to obtain the first foaming system; The method for preparing the second foaming system is to mix the auxiliary foaming agent sodium bicarbonate and the foaming aid uniformly at a temperature of 60-75° C., and then cool to obtain the second foaming system; The foaming aid is stearic acid and / or palmitic acid; The segmented premixing method comprises: uniformly mixing chlorinated polyvinyl chloride resin, organic tin main stabilizer, auxiliary stabilizer, lubricating agent, impact modifier, processing aid, foaming agent K500 and filler, heating to 110-120° C., adding the first foaming system, stopping heating and heat preservation, continuously mixing and cooling to 60° C., adding the second foaming system, uniformly mixing, cooling and obtaining a premix; The premix is ​​prepared into a raw material and foamed to obtain a rigid chlorinated polyvinyl chloride foam material.

[0008] Preferably, in the staged premix, 100 parts of chlorinated polyvinyl chloride resin, 2.5-8 parts of composite foaming agent system, 2-3.5 parts of organic tin main stabilizer, 1.5-3 parts of auxiliary stabilizer, 5-9.5 parts of impact modifier, 3.5-8 parts of lubricating aid, 3-5 parts of processing aid, and 1-3.5 parts of filler; The composite foaming agent system consists of a first foaming agent system, a second foaming agent system, and a foaming aid K500; the weight ratio of the first foaming agent system, the second foaming agent system, and the foaming aid K500 is 1.7-2.3:1:0.8-2.2.

[0009] Preferably, in the preparation of the first foaming system, the mixed solvent consists of acetonitrile and dimethyl sulfoxide, and the mass ratio of acetonitrile to dimethyl sulfoxide is 1:0.2-0.3; The mass ratio of the main foaming agent azodicarbonamide to the mixed solvent is 2-3:4.

[0010] Preferably, in the preparation of the first foaming system, the zinc oxide is common zinc oxide with an average particle size of 4-10 μm, and / or ultrafine zinc oxide with an average particle size of 0.5-3 μm; The average particle size of zinc stearate is 10-15 μm; The weight ratio of the main foaming agent azodicarbonamide, zinc oxide and zinc stearate is 0.48-1.8:0.08-0.25:0.48-1.9.

[0011] Preferably, in the preparation of the second foaming system, the particle size specification of the auxiliary foaming agent sodium bicarbonate is 1000 mesh; The weight ratio of the auxiliary foaming agent sodium bicarbonate to the foaming aid is 0.36-1.65:0.1-0.6.

[0012] Preferably, in the staged premixing, the chlorine content of the chlorinated polyvinyl chloride resin is 61-65wt%, and the melt viscosity is 1600-2400 Pa·s; The main organic tin stabilizer is at least one of the following: methyl tin mercaptan, butyl tin mercaptan, butyl tin laurate, butyl tin maleate; The auxiliary stabilizer is at least one of the following: antioxidant 1010, antioxidant 1076, antioxidant 1500, phosphite, hydrotalcite, and epoxidized soybean oil with an epoxy value of ≥6%.

[0013] Preferably, in the staged premixing, the lubricating agent is at least one of the following: paraffin, polyethylene wax, oxidized polyethylene wax, chlorinated paraffin, lubricant DOP, lubricant DINP, fatty acid ester G32; The impact modifier is at least one of the following: methacrylate impact modifier, methyl methacrylate / butadiene / styrene copolymer, chlorinated polyethylene, acrylonitrile / butadiene / styrene copolymer; The processing aid is at least one of the following: acrylic processing aid, processing aid LPN20, processing aid LPN80, processing aid 3316; The filler is at least one of the following: titanium dioxide, nano calcium carbonate, and talcum powder.

[0014] Furthermore, the method for preparing the embryo material is to place the premix in an open mill, control the processing roller temperature to 170-175° C., and obtain the embryo material; The foaming molding method comprises placing the material blank in a pressure molding machine, controlling the molding temperature to be 180° C., and performing foaming molding to obtain the rigid chlorinated polyvinyl chloride foaming material.

[0015] A rigid chlorinated polyvinyl chloride foam material is prepared by the above-mentioned preparation method.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) In the preparation of the rigid chlorinated polyvinyl chloride foam material of the present invention, in the preparation of the first foaming system, azodicarbonamide (ADC), a main foaming agent, is added to a mixed solvent. After forming a supersaturated solution at a relatively high dissolution temperature by utilizing the solubility of the main foaming agent azodicarbonamide (ADC) in the mixed solvent, a foaming aid zinc oxide is dispersed into the mixed solution, and the temperature is lowered. The main foaming agent azodicarbonamide (ADC) is cooled and precipitated onto the surface of zinc oxide particles to form ADC / ZnO coated particles. Then, the ADC / ZnO coated particles are mixed with zinc stearate, and the zinc stearate is melted and coated at a high temperature. to the outer surface of ADC / ZnO coated particles to form composite coated particles (i.e., the first foaming system); in the preparation of the second foaming system, the foaming aid (stearic acid / palmitic acid) is melted and coated on the surface of sodium bicarbonate by utilizing the characteristic that the melting point of the foaming aid (stearic acid / palmitic acid) is lower than that of sodium bicarbonate, and a coating is formed after cooling (i.e., the second foaming system); through the above-mentioned treatment, the foaming agent and the foaming aid in each foaming system are combined, the decomposition temperature of the first foaming system and the second foaming system is regulated to a similar level, the matching performance of the two is improved, the balance of heat absorption and heat release is achieved, and the foaming material is significantly improved through the effective cooperation of the two. The yellowing problem of the material; then in the staged premixing, after the main raw materials are mixed, the first foaming system is added under the condition of not higher than the melting temperature of zinc stearate; then the second foaming system is added under the condition of not higher than the melting temperature of the foaming aid (stearic acid / palmitic acid); avoid the first foaming system and the second foaming system from melting the outer layer of zinc stearate / stearic acid / palmitic acid during the staged premixing process, thereby causing the foaming components to directly contact with other raw materials in advance; through the specific process control of the above staged premixing, it is ensured that the bonding of the first foaming system and the second foaming system is not destroyed, thereby reducing the system temperature during the processing. And make the heat absorption and release temperatures of the main foaming agent and the auxiliary foaming agent in the formula system better match, reduce the tendency of material decomposition and yellowing caused by the large amount of heat released during the processing; the above-mentioned technical means cooperate with each other and work synergistically, which can effectively reduce the material temperature in the foaming preparation process of CPVC materials, avoid the yellowing and brittleness problems of CPVC materials after processing, improve the appearance of CPVC foamed products, reduce the occurrence of uneven foaming hole size, string holes and broken holes caused by CPVC decomposition, improve the impact resistance of CPVC materials, improve the rigidity of CPVC materials, and improve the deformation problem of CPVC materials.

[0017] (2) The method for preparing the rigid chlorinated polyvinyl chloride foam material of the present invention selects chlorinated polyvinyl chloride (CPVC) with different chlorine contents and viscosities and a specific composite foaming system and other additives to adjust the lubrication system according to the final application fields of the rigid chlorinated polyvinyl chloride foam material with different foaming ratios, so that the system viscosity of the chlorinated polyvinyl chloride (CPVC) premix is ​​adapted to the foaming ratio, and the premix can be ensured to have good fluidity and high melt strength at high, medium and low foaming, and further ensure the uniform dispersion and foaming ratio of the chlorinated polyvinyl chloride foam, as well as the thermal stability and dimensional stability of the rigid chlorinated polyvinyl chloride foam material.

[0018] (3) The rigid chlorinated polyvinyl chloride foam material of the present invention effectively solves the problem of decomposition and yellowing of the rigid chlorinated polyvinyl chloride foam material by matching the heat absorption and release balance and decomposition temperature of the first foaming system and the second foaming system; the color difference L, a, and b values ​​representing the degree of decomposition of the material in the low-foaming, medium-foaming, and high-foaming rigid chlorinated polyvinyl chloride foam materials prepared are significantly improved; compared with the control example, the b value is significantly reduced, and the yellowing of the L value and the a value is significantly improved, which has obvious advantages in light-colored chlorinated polyvinyl chloride foam decorative materials with flame retardant requirements.

[0019] (4) By selecting chlorinated polyvinyl chloride (CPVC) with different chlorine contents and viscosities and combining them with auxiliary agents such as a specific composite foaming system, the present invention improves the foaming ratio of the rigid chlorinated polyvinyl chloride foam material under high, medium and low foaming conditions to a certain extent compared with the comparative scheme in which the foaming system is not managed. The rigid chlorinated polyvinyl chloride foam material has good impact resistance and thermal stability; the foam cells are more fine and uniform, the surface is smooth and bright, and the comprehensive performance is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a sample picture of the rigid chlorinated polyvinyl chloride foam material of Comparative Example 1.

[0021] Figure 2 This is a sample picture of the rigid chlorinated polyvinyl chloride foam material of Example 1.

[0022] Figure 3 This is a sample picture of the rigid chlorinated polyvinyl chloride foam material of Comparative Example 2.

[0023] Figure 4 This is a sample picture of the rigid chlorinated polyvinyl chloride foam material of Example 2.

[0024] Figure 5 This is a sample picture of the rigid chlorinated polyvinyl chloride foam material of Comparative Example 3.

[0025] Figure 6 This is a sample picture of the rigid chlorinated polyvinyl chloride foam material of Example 3. DETAILED DESCRIPTION

[0026] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described. It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those of ordinary skill in the art to which the present invention belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] The embodiment of the present invention provides a method for preparing a rigid chlorinated polyvinyl chloride foam material, comprising the following steps: preparing a composite foaming system, premixing in stages, preparing a material embryo, and foaming and molding.

[0029] The preparation of the composite foaming system comprises the following steps: preparing a first foaming system and preparing a second foaming system.

[0030] The method for preparing the first foaming system comprises the following steps: adding azodicarbonamide (ADC), a main foaming agent, to a sealed container containing a mixed solvent of acetonitrile and dimethyl sulfoxide (DMSO), heating to 60-75° C. under stirring conditions of 120-170 rpm, and stirring at a constant temperature until the material becomes a transparent solution; continuously adding zinc oxide, a foaming aid, stirring continuously and cooling to below 35° C., transferring the obtained solution and filtering it under negative pressure suction to obtain a solid substance, and recycling the liquid (mixed solvent); transferring the solid substance to a mixer, heating to 85-95° C. under stirring conditions of 450-550 rpm, stirring at a constant temperature for 3-10 minutes, adding zinc stearate, a foaming aid, heating to 120-135° C. under stirring conditions, stirring at a constant temperature for 1.5 minutes, transferring the solution to a cooling container, cooling to 40° C. under stirring conditions of 40-60 rpm, and then discharging the solution to obtain the first foaming system.

[0031] In the preparation of the first foaming system, the mass ratio of acetonitrile to DMSO in the mixed solvent is 1:0.2-0.3; The mass ratio of the main foaming agent azodicarbonamide ADC to the mixed solvent is 2-3:4; The weight ratio of the main foaming agent azodicarbonamide ADC, the foaming auxiliary agent zinc oxide, and the foaming auxiliary agent zinc stearate is 0.48-1.8:0.08-0.25:0.48-1.9 In the preparation of the first foaming system, the particle size of the main foaming agent azodicarbonamide ADC is 12-30 μm; The zinc oxide is ordinary zinc oxide (average particle size is 4-10 μm) and / or ultrafine zinc oxide (average particle size is 0.5-3 μm); The average particle size of zinc stearate is 10-15 μm.

[0032] The method for preparing the second foaming system is to add an auxiliary foaming agent, sodium bicarbonate, and a foaming aid (stearic acid and / or palmitic acid) into a small mixer, raise the temperature to 60-75° C. under stirring conditions at 600-700 rpm, reduce the speed to 300-400 rpm, cool to below 45° C., and then discharge the material to obtain the second foaming system.

[0033] In the preparation of the second foaming system, the particle size specification of the auxiliary foaming agent sodium bicarbonate is 1000 mesh; The weight ratio of the auxiliary foaming agent sodium bicarbonate to the foaming aid (stearic acid / palmitic acid) is 0.36-1.65:0.1-0.6.

[0034] In the preparation of the first foaming system, azodicarbonamide (ADC), a main foaming agent, is added to a mixed solvent. The solubility of the main foaming agent azodicarbonamide (ADC) in the mixed solvent is utilized to form a supersaturated solution under a relatively high dissolution temperature condition. Then, zinc oxide, a foaming aid, is dispersed into the mixed solution. The temperature is lowered, and the main foaming agent azodicarbonamide (ADC) is cooled and precipitated onto the surface of zinc oxide particles to form ADC / ZnO coated particles. Then, the ADC / ZnO coated particles are mixed with zinc stearate, and the zinc stearate is melted and coated onto the outer surface of the ADC / ZnO coated particles under high temperature conditions to form composite coated particles (i.e., the first foaming system). In the preparation of the second foaming system, a foaming aid (stearic acid) is utilized to form a supersaturated solution. According to the characteristic that the melting point of stearic acid / palmitic acid is lower than that of sodium bicarbonate, the foaming aid (stearic acid / palmitic acid) is melted and coated on the surface of sodium bicarbonate, and a coating (i.e., the second foaming system) is formed after cooling; through the above-mentioned treatment, the foaming agent and the foaming aid in each foaming system are combined, the decomposition temperature of the first foaming system and the second foaming system are regulated to a similar level, the matching performance of the two is improved, the balance of heat absorption and heat release is achieved, the yellowing problem of the foaming material is effectively improved, the appearance of CPVC foamed products is improved, the occurrence of uneven foaming hole size, string holes and broken holes caused by the decomposition of CPVC is reduced, the impact resistance of CPVC materials is improved, the rigidity of CPVC materials is improved, and the deformation problem of CPVC materials is improved.

[0035] The segmented premixing method comprises the following steps: adding chlorinated polyvinyl chloride resin CPVC, an organic tin main stabilizer and an auxiliary stabilizer into a high-speed mixer, adjusting the stirring speed to 1000-1200 rpm, stirring and heating to 70-85° C., adding a lubricating agent, and adjusting the stirring speed to 600-800 rpm after uniform mixing, adding an impact modifier, a processing aid, K500 and a filler, stirring and heating to 110-120° C., reducing the stirring speed to 300-400 rpm, adding a first foaming system, stopping heating and heat preservation, continuously stirring and cooling to 60° C., adding a second foaming system, stirring uniformly, transferring the mixed material in the high-speed mixer into a cold mixer, stirring and cooling to 35° C. at 40-60 rpm, and discharging the material to obtain a premix.

[0036] In the staged premixing, the weight proportions of the raw materials are: 100 parts of chlorinated polyvinyl chloride resin CPVC, 2.5-8 parts of composite foaming agent system (the sum of the first foaming agent system, the second foaming agent system and the foaming aid K500), 2-3.5 parts of organic tin main stabilizer, 1.5-3 parts of auxiliary stabilizer, 5-9.5 parts of impact modifier, 3.5-8 parts of lubricating aid, 3-5 parts of processing aid and 1-3.5 parts of filler.

[0037] The weight ratio of the first foaming agent system, the second foaming agent system and the foaming aid K500 is 1.7-2.3:1:0.8-2.2.

[0038] In the staged premixing, the chlorine content of the chlorinated polyvinyl chloride resin CPVC is 61-65wt%, and the melt viscosity is 1600-2400 Pa·s; The main organic tin stabilizer is at least one of the following: methyl tin mercaptan, butyl tin mercaptan, butyl tin laurate, butyl tin maleate; The auxiliary stabilizer is at least one of the following: antioxidant 1010, antioxidant 1076, antioxidant 1500, phosphite, epoxidized soybean oil ESO (epoxy value ≥ 6%), hydrotalcite; The lubricating agent is at least one of the following: paraffin, polyethylene wax PEW, oxidized polyethylene wax OPE, chlorinated paraffin, lubricant DOP, lubricant DINP, fatty acid ester G32; The impact modifier is at least one of the following: methacrylate impact modifier ACR (molecular weight 1500000-2500000), methyl methacrylate / butadiene / styrene copolymer MBS, chlorinated polyethylene CPE, acrylonitrile / butadiene / styrene copolymer ABS; The processing aid is at least one of the following: acrylic processing aid (PA20, ACR401, ACR201), processing aid LPN20, processing aid LPN80, processing aid 3316; The filler is at least one of the following: titanium dioxide, nano calcium carbonate (average particle size ≤ 60nm), and talcum powder.

[0039] In the staged premixing, after the main raw materials are mixed, the first foaming system is added under the condition of not higher than the melting temperature of zinc stearate; then, the second foaming system is added under the condition of not higher than the melting temperature of the foaming aid (stearic acid / palmitic acid); the first foaming system and the second foaming system are prevented from melting of the outer layer of zinc stearate / stearic acid / palmitic acid coated during the staged premixing process, thereby causing the foaming components to directly contact with other raw materials in advance.

[0040] The method for preparing the embryo material comprises placing the premix in an open mill for tableting, controlling the initial roller temperature of the open mill for tableting to be 170-175° C. and the roller distance to be 0.2 mm, performing packing and plasticizing after film forming, controlling the roller temperature of the open mill to be 170-175° C. and the roller distance to be 0.2 mm to plasticize 10 triangular bags, then adjusting the roller distance of the open mill to 5 mm, rolling for 5 times while keeping the roller temperature constant, and then discharging the sheet to obtain the embryo material.

[0041] The foaming molding method is as follows: placing the blank in a mold (the thickness of the mold cavity is 5 mm) preheated at 180°C in a flat vulcanizer, and then placing the mold in a pressure molding machine at a temperature of 180°C, preheating for 2-5 minutes under 0.1MPa conditions, pressurizing by no less than 15MPa, maintaining the pressure for 5-10 minutes, and releasing the pressure for foaming molding to obtain a rigid chlorinated polyvinyl chloride foam material.

[0042] The embodiment of the present invention also provides a rigid chlorinated polyvinyl chloride foam material prepared by the above method.

[0043] The present invention is further described below in conjunction with some specific embodiments.

[0044] Example 1 and Comparative Example 1 are low foaming solutions, and the models / specifications and specific weight amounts of the raw materials used are shown in the following table:

[0045] Example 1 This embodiment provides a method for preparing a rigid chlorinated polyvinyl chloride foam material. After preparing the materials according to the weight parts of each raw material in the above table, the specific preparation steps are as follows: 1. Preparation of composite foaming system 1) Preparation of the first foaming system The main foaming agent azodicarbonamide ADC is added to a closed container containing a mixed solvent of acetonitrile and dimethyl sulfoxide DMSO, heated to 65°C under stirring at 150rpm, and stirred at a constant temperature until the material becomes a transparent solution; the foaming aid zinc oxide is continued to be added, the stirring is continued and the temperature is lowered to below 35°C, the obtained solution is transferred and filtered by negative pressure suction to obtain a solid substance, and the liquid (mixed solvent) is reused; the solid substance is transferred to a mixer, heated to 90°C under stirring at 500rpm, stirred at a constant temperature for 5min, and then the foaming aid zinc stearate is added, the temperature is raised to 125°C under stirring, stirred at a constant temperature for 2min, and then transferred to a cooling container, cooled to 40°C under stirring at 50rpm, and then discharged to obtain a first foaming system.

[0046] Wherein, the weight ratio of acetonitrile to DMSO in the mixed solvent is 1:0.3.

[0047] The weight ratio of the main foaming agent azodicarbonamide ADC to the mixed solvent is 2:4.

[0048] The foaming auxiliary agent zinc oxide is ordinary zinc oxide.

[0049] The weight ratio of the main foaming agent azodicarbonamide ADC, the foaming auxiliary agent zinc oxide, and the foaming auxiliary agent zinc stearate is 0.48:0.08:0.48.

[0050] 2) Preparation of the second foaming system The auxiliary foaming agent sodium bicarbonate and the foaming aid (stearic acid) were added into a small mixer, and the temperature was raised to 60°C under stirring at 600 rpm, and the rotation speed was reduced to 400 rpm. After cooling to below 45°C, the material was discharged to obtain a second foaming system.

[0051] Among them, the weight ratio of the auxiliary foaming agent sodium bicarbonate and the foaming aid (stearic acid) is 0.36:0.1.

[0052] 2. Segmented premixing Add chlorinated polyvinyl chloride resin CPVC, organic tin main stabilizer (methyl tin mercaptan), auxiliary stabilizer (antioxidant 1076, antioxidant 1500, epoxy soybean oil ESO) into a high-speed mixer, adjust the stirring speed to 1200 rpm, stir and heat to 85°C, add lubricating agent, mix and stir for 4 minutes, adjust the stirring speed to 800 rpm, add impact modifier, processing aid, foaming aid K500, filler, stir and heat to 110°C, reduce the stirring speed to 400 rpm, add the first foaming system, stir and cool to 60°C, add the second foaming system, stir evenly, transfer the mixed material in the high-speed mixer to a cold mixer, stir at 50 rpm and cool to 35°C, discharge the material to obtain a premix.

[0053] Among them, the weight proportions of each raw material are: 100 parts of chlorinated polyvinyl chloride resin CPVC, 2.5 parts of composite foaming agent system (the sum of the first foaming agent system, the second foaming agent system and the foaming aid K500), 2 parts of organic tin main stabilizer, 3 parts of auxiliary stabilizer, 9.5 parts of impact modifier, 3.5 parts of lubricating aid, 3 parts of processing aid, and 1 part of filler.

[0054] The weight ratio of the first foaming agent system, the second foaming agent system, and the foaming aid K500 is 2.26:1:2.17.

[0055] The high-speed mixer is provided with upper and lower layers of stirring paddles, which are staggered up and down to form a cross shape; and the top cover plate is provided with a spoiler.

[0056] The chlorine content of chlorinated polyvinyl chloride resin CPVC is 61wt% and the melt viscosity is 1670Pa·s.

[0057] The lubricating additives are paraffin, fatty acid ester G32, and oxidized polyethylene wax OPE.

[0058] The impact modifier is methyl methacrylate / butadiene / styrene copolymer MBS, acrylate impact modifier KM355P (belongs to methacrylate impact modifier ACR).

[0059] The processing aids include processing aid LPN20 and processing aid 3316.

[0060] The fillers are titanium dioxide (rutile titanium dioxide) and nano calcium carbonate.

[0061] 3. Prepare embryo The premix was placed in an open mixer for tableting. The initial roller temperature of the mixer was controlled to be 170°C and the roller distance was 0.2mm. After the film was formed, the premix was packaged and plasticized. The roller temperature of the mixer was controlled to be 170°C and the roller distance was 0.2mm to plasticize 10 triangular packages. Then the roller distance of the mixer was adjusted to 5mm. While keeping the roller temperature constant, the premix was rolled 5 times and then the sheet was produced to obtain the embryo.

[0062] 4. Foaming The blank was placed in a mold (mold cavity thickness was 5 mm) preheated at 180°C in a flat vulcanizer, and then the mold was placed in a pressure molding machine at 180°C. After preheating for 2 minutes at 0.1 MPa, the mold was pressurized to 15 MPa, maintained at the pressure for 5 minutes, and then released for foaming to obtain a rigid chlorinated polyvinyl chloride foam material.

[0063] This embodiment also provides a rigid chlorinated polyvinyl chloride foam material, which is prepared by the aforementioned preparation method.

[0064] Comparative Example 1 Different from Example 1, the technical solution of Comparative Example 1 is to pre-mix the main foaming agent, the auxiliary foaming agent and the foaming aid into a composite foaming agent, and then directly mix it with other raw materials of the rigid chlorinated polyvinyl chloride foaming material. The specific preparation steps of the rigid chlorinated polyvinyl chloride foaming material are as follows: 1. Prepare the materials according to the weight of each raw material in the above table.

[0065] 2. Place the main foaming agent azodicarbonamide ADC, the auxiliary foaming agent sodium bicarbonate, zinc stearate, stearic acid, ordinary zinc oxide and the foaming aid K500 in a small mixer, stir and heat to 60°C to form a composite foaming agent.

[0066] 3. Add chlorinated polyvinyl chloride resin CPVC, composite foaming agent and other auxiliary materials except lubricating agent into a high-speed mixer, adjust the stirring speed to 1200 rpm, stir and heat to 70°C, add lubricating agent, adjust the stirring speed of the mixer to 800 rpm, stir and heat to 110°C under this condition; transfer to a cold mixer, stir and cool to below 40°C, discharge the material to obtain a premix.

[0067] 4. Place the premix in an open mixer for tableting. Control the initial roller temperature of the open mixer to 170°C and the roller distance to 0.2mm. After the film is formed, pack and plasticize. Control the roller temperature of the open mixer to 170°C and the roller distance to 0.2mm to plasticize 10 triangular bags. Then adjust the roller distance of the open mixer to 5mm. Keep the roller temperature constant and roll 5 times to get the sheet to obtain the embryo.

[0068] 5. Place the blank in a mold (mold cavity thickness is 5 mm) preheated at 180°C in a flat vulcanizer, and then place the mold in a pressure molding machine at a temperature of 180°C. After preheating for 2 minutes at 0.1MPa, pressurize to 15MPa, maintain the pressure for 5 minutes, release the pressure and perform foaming to obtain a rigid chlorinated polyvinyl chloride foam material.

[0069] Example 2 and Comparative Example 2 are medium foaming solutions, and the models / specifications and specific weight amounts of the raw materials used are shown in the following table:

[0070] Example 2 This embodiment provides a method for preparing a rigid chlorinated polyvinyl chloride foam material. After preparing the materials according to the weight parts of each raw material in the above table, the specific preparation steps are as follows: 1. Preparation of composite foaming system 1) Preparation of the first foaming system The main foaming agent azodicarbonamide ADC is added to a closed container containing a mixed solvent of acetonitrile and dimethyl sulfoxide DMSO, heated to 70°C under stirring at 130rpm, and stirred at a constant temperature until the material becomes a transparent solution; the foaming aid zinc oxide is continued to be added, the stirring is continued and the temperature is lowered to below 35°C, the obtained solution is transferred and filtered by vacuum suction to obtain a solid substance, and the liquid (mixed solvent) is reused; the solid substance is transferred to a mixer, heated to 95°C under stirring at 550rpm, stirred at a constant temperature for 3min, and then the foaming aid zinc stearate is added, the temperature is raised to 130°C under stirring, stirred at a constant temperature for 2min, and then transferred to a cooling container, cooled to 40°C under stirring at 60rpm, and then discharged to obtain a first foaming system.

[0071] Wherein, the ratio of acetonitrile to DMSO in the mixed solvent is 1:0.23.

[0072] The ratio of the main blowing agent azodicarbonamide ADC to the mixed solvent is 2.6:4.

[0073] The zinc oxide as a foaming auxiliary agent is common zinc oxide and superfine zinc oxide; the weight ratio of the common zinc oxide to the superfine zinc oxide is 0.05:0.1.

[0074] The weight ratio of the main foaming agent azodicarbonamide ADC, the foaming auxiliary agent zinc oxide, and the foaming auxiliary agent zinc stearate is 1.15:0.15:1.1.

[0075] 2) Preparation of the second foaming system The auxiliary foaming agent sodium bicarbonate and the foaming aids (stearic acid and palmitic acid) were added into a small mixer, the temperature was raised to 70°C under stirring conditions at 700 rpm, the speed was reduced to 300 rpm, and after cooling to below 45°C, the material was discharged to obtain a second foaming system.

[0076] Among them, the weight ratio of auxiliary foaming agents sodium bicarbonate, stearic acid and palmitic acid is 0.95:0.2:0.15.

[0077] 2. Segmented premixing Add chlorinated polyvinyl chloride resin CPVC, organic tin main stabilizer (methyl tin mercaptan, butyl tin mercaptan), auxiliary stabilizer (antioxidant 1076, epoxy soybean oil ESO) into a high-speed mixer, adjust the stirring speed to 1100 rpm, stir and heat to 80°C, add lubricating agent, mix for 5 minutes, adjust the stirring speed to 700 rpm, add impact modifier, processing aid, foaming aid K500, filler, stir and heat to 115°C, reduce the stirring speed to 350 rpm, add the first foaming system, stir and cool to 60°C, add the second foaming system, stir evenly, transfer the mixed material in the high-speed mixer into a cold mixer, stir and cool to 35°C at 60 rpm, discharge the material, and obtain a premix.

[0078] Among them, the weight proportions of each raw material are: 100 parts of chlorinated polyvinyl chloride resin CPVC, 5 parts of composite foaming agent system (the sum of the first foaming agent system, the second foaming agent system and the foaming aid K500), 3.5 parts of organic tin main stabilizer, 1.5 parts of auxiliary stabilizer, 7 parts of impact modifier, 4.5 parts of lubricating aid, 4 parts of processing aid, and 2 parts of filler.

[0079] The weight ratio of the first foaming agent system, the second foaming agent system, and the foaming aid K500 is 1.85:1:1.

[0080] The high-speed mixer is provided with upper and lower layers of stirring paddles, which are staggered up and down to form a cross shape; and the top cover plate is provided with a spoiler.

[0081] The chlorine content of chlorinated polyvinyl chloride resin CPVC is 63wt% and the melt viscosity is 1980Pa·s.

[0082] The lubricating additives are paraffin, fatty acid ester G32, and oxidized polyethylene wax OPE.

[0083] The impact modifier is methyl methacrylate / butadiene / styrene copolymer MBS, acrylate impact modifier KM355P (belongs to methacrylate impact modifier ACR).

[0084] The processing aids include processing aid LPN20 and processing aid 3316.

[0085] The fillers are titanium dioxide (rutile titanium dioxide) and nano calcium carbonate.

[0086] 3. Prepare embryo The premix was placed in an open mixer for tableting. The initial roller temperature of the mixer was controlled to be 175°C and the roller distance was 0.2mm. After the film was formed, the premix was packaged and plasticized. The roller temperature of the mixer was controlled to be 175°C and the roller distance was 0.2mm to plasticize 10 triangular bags. Then the roller distance of the mixer was adjusted to 5mm. While keeping the roller temperature constant, the premix was rolled 5 times and the sheet was obtained.

[0087] 4. Foaming The blank was placed in a mold (mold cavity thickness was 5 mm) preheated at 180°C in a flat vulcanizer, and then the mold was placed in a pressure molding machine at 180°C. After preheating for 2 minutes at 0.1 MPa, the mold was pressurized to 15 MPa, maintained at the pressure for 5 minutes, and then released for foaming to obtain a rigid chlorinated polyvinyl chloride foam material.

[0088] This embodiment also provides a rigid chlorinated polyvinyl chloride foam material, which is prepared by the aforementioned preparation method.

[0089] Comparative Example 2 Different from Example 2, the technical scheme of Comparative Example 2 is that the main foaming agent is first dissolved in a solvent to prepare a main foaming agent solution, and then other raw materials of the rigid chlorinated polyvinyl chloride foaming material are mixed with the auxiliary foaming agent and the foaming aid, and then the main foaming agent solution is added by spraying. The specific preparation steps of the rigid chlorinated polyvinyl chloride foaming material are as follows: 1. Prepare the materials according to the weight of each raw material in the above table.

[0090] 2. Add the main blowing agent azodicarbonamide (ADC) into a sealed container containing a mixed solvent of acetonitrile and dimethyl sulfoxide (DMSO), heat to 70°C while stirring, stir at a constant temperature until the material becomes a transparent solution, and cool to obtain a main blowing agent solution.

[0091] 3. Add chlorinated polyvinyl chloride resin CPVC, organic tin main stabilizer and auxiliary stabilizer to a high-speed mixer, adjust the stirring speed to 1100 rpm, stir and heat to 80°C, add lubricating agent, mix well and adjust the stirring speed to 700 rpm, add impact modifier, processing aid, foaming aid K500 and filler, stir and heat to 95°C, reduce the stirring speed to 350 rpm, add auxiliary foaming agent sodium bicarbonate, foaming aid and filler, use a spray device to add the main foaming agent solution prepared above, control the spray addition rate of the main foaming agent solution to 120 mL / min, and control the main foaming agent solution to be added in 20 min; then, under the stirring speed of 400 rpm, stir and heat to 115°C, put it into a cold mixer, stir and cool to 35°C to discharge, and obtain a premix.

[0092] 4. Place the premix in an open mixer for tableting. Control the initial roller temperature of the open mixer to 175°C and the roller distance to 0.2mm. After the film is formed, pack and plasticize. Control the roller temperature of the open mixer to 175°C and the roller distance to 0.2mm to plasticize 10 triangular bags. Then adjust the roller distance of the open mixer to 5mm. Keep the roller temperature constant and roll 5 times to get the sheet to obtain the embryo.

[0093] 5. Place the blank in a mold (mold cavity thickness is 5 mm) preheated at 180°C in a flat vulcanizer, and then place the mold in a pressure molding machine at a temperature of 180°C. After preheating for 2 minutes at 0.1MPa, pressurize to 15MPa, maintain the pressure for 5 minutes, release the pressure and perform foaming to obtain a rigid chlorinated polyvinyl chloride foam material.

[0094] Example 3 and Comparative Example 3 are high foaming solutions, and the types / specifications and specific weight amounts of the raw materials used are shown in the following table:

[0095] Example 3 This embodiment provides a method for preparing a rigid chlorinated polyvinyl chloride foam material. After preparing the materials according to the weight parts of each raw material in the above table, the specific preparation steps are as follows: 1. Preparation of composite foaming system 1) Preparation of the first foaming system The main foaming agent azodicarbonamide ADC is added to a closed container containing a mixed solvent of acetonitrile and dimethyl sulfoxide DMSO, heated to 75°C under stirring at 130rpm, and stirred at a constant temperature until the material becomes a transparent solution; the foaming aid zinc oxide is continued to be added, the stirring is continued and the temperature is lowered to below 35°C, the obtained solution is transferred and filtered by vacuum suction to obtain a solid substance, and the liquid (mixed solvent) is reused; the solid substance is transferred to a mixer, heated to 95°C under stirring at 450rpm, stirred at a constant temperature for 3min, and then the foaming aid zinc stearate is added, the temperature is raised to 135°C under stirring, stirred at a constant temperature for 1.5min, and then transferred to a cooling container, cooled to 40°C under stirring at 45rpm, and then discharged to obtain a first foaming system.

[0096] Wherein, the ratio of acetonitrile to DMSO in the mixed solvent is 1:0.2.

[0097] The ratio of the main blowing agent azodicarbonamide ADC to the mixed solvent is 3:4.

[0098] The zinc oxide is common zinc oxide and ultrafine zinc oxide; the weight ratio of the common zinc oxide to the ultrafine zinc oxide is 0.05:0.2.

[0099] The weight ratio of the main foaming agent azodicarbonamide ADC, the foaming auxiliary agent zinc oxide, and the foaming auxiliary agent zinc stearate is 1.8:0.25:1.9.

[0100] 2) Preparation of the second foaming system The auxiliary foaming agent sodium bicarbonate and the foaming aids (stearic acid and palmitic acid) were added into a small mixer, heated to 75°C under stirring at 700rpm, the speed was reduced to 300rpm, and after cooling to below 45°C, the material was discharged to obtain a second foaming system.

[0101] Among them, the weight ratio of auxiliary foaming agents sodium bicarbonate, stearic acid and palmitic acid is 1.65:0.4:0.2.

[0102] 2. Segmented premixing Add chlorinated polyvinyl chloride resin CPVC, organic tin main stabilizer (methyl tin mercaptan, butyl tin mercaptan), auxiliary stabilizer (antioxidant 1076, antioxidant 1500, epoxy soybean oil ESO) into a high-speed mixer, adjust the stirring speed to 1000 rpm, stir and heat to 70°C, add lubricating agent, adjust the stirring speed to 600 rpm after mixing for 6 minutes, add impact modifier, processing aid, foaming aid K500, filler, stir and heat to 120°C, reduce the stirring speed to 300 rpm, add the first foaming system, stir and cool to 60°C, add the second foaming system, stir and cool to 60°C, transfer the mixed material in the high-speed mixer to a cold mixer, stir and cool to 35°C at 60 rpm, discharge the material, and obtain a premix.

[0103] Among them, the weight proportions of each raw material are: 100 parts of chlorinated polyvinyl chloride resin CPVC, 8 parts of composite foaming agent system (the sum of the first foaming agent system, the second foaming agent system and the foaming aid K500), 3.5 parts of organic tin main stabilizer, 2.5 parts of auxiliary stabilizer, 5 parts of impact modifier, 6 parts of lubricating aid, 5 parts of processing aid, and 2.5 parts of filler.

[0104] The weight ratio of the first foaming agent system, the second foaming agent system, and the foaming aid K500 is 1.75:1:0.8.

[0105] The high-speed mixer is provided with upper and lower layers of stirring paddles, which are staggered up and down to form a cross shape; and the top cover plate thereof is provided with a spoiler.

[0106] The chlorine content of chlorinated polyvinyl chloride resin CPVC is 65% and the melt viscosity is 2350 Pa·s.

[0107] The lubricating additives are paraffin, fatty acid ester G32, oxidized polyethylene wax OPE, and chlorinated paraffin.

[0108] The impact modifier is methyl methacrylate / butadiene / styrene copolymer MBS.

[0109] The processing aids include processing aid LPN20 and processing aid 3316.

[0110] The fillers are titanium dioxide (rutile titanium dioxide) and nano calcium carbonate.

[0111] 3. Prepare embryo The premix was placed in an open mixer for tableting. The initial roller temperature of the mixer was controlled to be 175°C and the roller distance was 0.2mm. After the film was formed, the premix was packaged and plasticized. The roller temperature of the mixer was controlled to be 175°C and the roller distance was 0.2mm to plasticize 10 triangular bags. Then the roller distance of the mixer was adjusted to 5mm. While keeping the roller temperature constant, the premix was rolled 5 times and the sheet was obtained.

[0112] 4. Foaming The blank was placed in a mold (mold cavity thickness was 5 mm) preheated at 180°C in a flat vulcanizer, and then the mold was placed in a pressure molding machine at 180°C. After preheating for 2 minutes at 0.1 MPa, the mold was pressurized to 15 MPa, maintained at the pressure for 5 minutes, and then released for foaming to obtain a rigid chlorinated polyvinyl chloride foam material.

[0113] This embodiment also provides a rigid chlorinated polyvinyl chloride foam material, which is prepared by the aforementioned preparation method.

[0114] Comparative Example 3 Different from Example 3, the technical scheme of Comparative Example 3 is that the main foaming agent is first dissolved in a solvent to prepare a main foaming agent solution, and then other raw materials of the rigid chlorinated polyvinyl chloride foaming material are mixed with the auxiliary foaming agent and the foaming aid, and then the main foaming agent solution is added by spraying. The specific preparation steps of the rigid chlorinated polyvinyl chloride foaming material are as follows: 1. Prepare the materials according to the weight of each raw material in the above table.

[0115] 2. Add the main blowing agent azodicarbonamide (ADC) into a sealed container containing a mixed solvent of acetonitrile and dimethyl sulfoxide (DMSO), heat to 70°C while stirring, stir at a constant temperature until the material becomes a transparent solution, and cool to obtain a main blowing agent solution.

[0116] 3. Add chlorinated polyvinyl chloride resin CPVC, organic tin main stabilizer and auxiliary stabilizer to a high-speed mixer, adjust the stirring speed to 1000 rpm, stir and heat to 70°C, add lubricating agent, mix for 6 minutes, adjust the stirring speed to 600 rpm, add impact modifier, processing aid and filler, stir and heat to 90°C, reduce the stirring speed to 300 rpm, add auxiliary foaming agent sodium bicarbonate, foaming aid, foaming aid K500 and filler, use a spray device to add the main foaming agent solution prepared above, control the spray addition rate of the main foaming agent solution to 150 mL / min, and control the main foaming agent solution to be added in 25 minutes; then, under the stirring speed of 300 rpm, stir and heat to 120°C, put it into a cold mixer, stir and cool to 35°C, and discharge to obtain a premix.

[0117] 4. Place the premix in an open mixer for tableting. Control the initial roller temperature of the open mixer to 175°C and the roller distance to 0.2mm. After the film is formed, pack and plasticize. Control the roller temperature of the open mixer to 175°C and the roller distance to 0.2mm to plasticize 10 triangular bags. Then adjust the roller distance of the open mixer to 5mm. Keep the roller temperature constant and roll 5 times to get the sheet to obtain the embryo.

[0118] 5. Place the blank in a mold (mold cavity thickness is 5 mm) preheated at 180°C in a flat vulcanizer, and then place the mold in a pressure molding machine at a temperature of 180°C. After preheating for 2 minutes at 0.1MPa, pressurize to 15MPa, maintain the pressure for 5 minutes, release the pressure and perform foaming to obtain a rigid chlorinated polyvinyl chloride foam material.

[0119] The tensile modulus, Rockwell hardness, heat deformation temperature HDT, 100°C heating deformation rate, apparent density, foaming ratio, notched impact strength, surface color difference, cell size, and cell dispersion of the rigid chlorinated polyvinyl chloride foam materials obtained in Examples 1-3 and Comparative Examples 1-3 were tested respectively, and the specific results are shown in the following table:

[0120] Note: The L value in the surface color difference represents the brightness, which is related to the black and white of the sample and the surface brightness; the a value represents whether it is reddish or greenish, a positive value indicates reddish, and a negative value indicates greenish; the b value represents whether it is yellowish or bluish, a positive value indicates yellowish, and a negative value indicates bluish. In the decomposition process of polyvinyl chloride foam material, the material turns red first and then yellow. The redder and yellower the color (that is, the larger the values ​​of a and b), the higher the degree of decomposition of the material, and vice versa, the better the stability of the material.

[0121] In the preparation of the rigid chlorinated polyvinyl chloride foam material of the present invention, the decomposition temperatures of the aforementioned high-temperature foaming agent azodicarbonamide and the low-temperature foaming agent sodium bicarbonate are quite different, and the low-temperature foaming agent is mostly decomposed before the high-temperature foaming agent azodicarbonamide begins to decompose, and the decomposition temperatures of the two are not well matched. The inventors have found through research that although the use of a foaming aid to adjust the decomposition temperature of the high-temperature foaming agent azodicarbonamide and the low-temperature foaming agent sodium bicarbonate has a certain effect, simply mixing and adding them to the raw materials of the rigid chlorinated polyvinyl chloride foam material cannot achieve molecular-level distribution, and they can only be embedded in the raw material formula system in the form of particles, resulting in the problem of separation of the foaming agent and the foaming aid, and the problem of mismatching the decomposition temperatures of the high-temperature foaming agent and the low-temperature foaming agent cannot be effectively solved. Although it has little effect on the foaming ratio of rigid chlorinated polyvinyl chloride foam materials, it is unable to achieve the heat absorption and release balance and decomposition temperature matching of high-temperature foaming agents and low-temperature foaming agents. Rigid chlorinated polyvinyl chloride foam materials are seriously yellowed. CPVC materials still have problems such as poor cell size and cell uniformity, low notch impact strength and easy deformation.

[0122] In the preparation of the rigid chlorinated polyvinyl chloride foaming material of the present invention, in the preparation of the first foaming system, azodicarbonamide (ADC), a main foaming agent, is added to a mixed solvent, and a supersaturated solution is formed under a relatively high dissolution temperature condition by utilizing the solubility of the main foaming agent azodicarbonamide (ADC) in the mixed solvent, and then a foaming auxiliary agent zinc oxide is dispersed in the mixed solution, and the temperature is lowered, and the main foaming agent azodicarbonamide (ADC) is cooled and precipitated on the surface of zinc oxide particles to form ADC / ZnO coated particles; then the ADC / ZnO coated particles are mixed with zinc stearate, and the zinc stearate is melted and coated under high temperature conditions. to the outer surface of ADC / ZnO coated particles to form composite coated particles (i.e., the first foaming system); in the preparation of the second foaming system, the foaming aid (stearic acid / palmitic acid) is melted and coated on the surface of sodium bicarbonate by utilizing the characteristic that the melting point of the foaming aid (stearic acid / palmitic acid) is lower than that of sodium bicarbonate, and a coating is formed after cooling (i.e., the second foaming system); through the above-mentioned treatment, the foaming agent and the foaming aid in each foaming system are combined, the decomposition temperature of the first foaming system and the second foaming system is regulated to a similar level, the matching performance of the two is improved, the balance of heat absorption and heat release is achieved, and the yellowing problem of the foaming material is effectively improved. ; Then, in the staged premixing, after the main raw materials are mixed, the first foaming system is added under the condition of not higher than the melting temperature of zinc stearate; then, the second foaming system is added under the condition of not higher than the melting temperature of the foaming aid (stearic acid / palmitic acid); the first foaming system and the second foaming system are prevented from melting of the outer layer of zinc stearate / stearic acid / palmitic acid during the staged premixing process, thereby causing the foaming components to directly contact with other raw materials in advance; through the specific process control of the above staged premixing, it is ensured that the bonding of the first foaming system and the second foaming system is not destroyed, thereby lowering the system temperature during the processing and making the formulation The heat absorption and release temperatures of the main foaming agent and the auxiliary foaming agent in the system are better matched, reducing the tendency of material decomposition and yellowing caused by the large amount of heat released during the processing; the above-mentioned technical means cooperate with each other and work synergistically, which can effectively reduce the material temperature during the foaming preparation process of the CPVC material, avoid the yellowing and brittleness problems of the CPVC material after processing, improve the appearance of the CPVC foamed products, reduce the occurrence of uneven foaming hole size, string holes and broken holes caused by the decomposition of CPVC, improve the impact resistance of the CPVC material, improve the rigidity of the CPVC material, and improve the deformation problem of the CPVC material.

[0123] The method for preparing the rigid chlorinated polyvinyl chloride foam material of the present invention selects chlorinated polyvinyl chloride (CPVC) with different chlorine contents and viscosities and a specific composite foaming system and other auxiliary agents to adjust the lubrication system according to the final application fields of the rigid chlorinated polyvinyl chloride foam material with different foaming ratios, so that the system viscosity of the chlorinated polyvinyl chloride (CPVC) premix is ​​adapted to the foaming ratio, and the premix can be ensured to have good fluidity and high melt strength when the foaming ratio is high, medium or low, and the uniform dispersibility and foaming ratio of the chlorinated polyvinyl chloride foaming, as well as the thermal stability and dimensional stability of the rigid chlorinated polyvinyl chloride foam material are further ensured.

[0124] Unless otherwise specified, all percentages used in the present invention are by mass.

[0125] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a rigid chlorinated polyvinyl chloride foam material, characterized in that: The method comprises the following steps: preparing a composite foaming system, premixing in sections, preparing a raw material, and foaming and molding; The preparation of the composite foaming system comprises the following steps: preparing a first foaming system, preparing a second foaming system; The method for preparing the first foaming system comprises: adding azodicarbonamide, a main foaming agent, into a mixed solvent, heating and dissolving it, adding zinc oxide, cooling and separating to obtain a solid substance; mixing the solid substances at a temperature of 85-95° C., heating to 120-135° C., mixing the solid substances and zinc stearate uniformly, and cooling to obtain the first foaming system; The method for preparing the second foaming system is to mix the auxiliary foaming agent sodium bicarbonate and the foaming aid uniformly at a temperature of 60-75° C., and then cool to obtain the second foaming system; The foaming aid is stearic acid and / or palmitic acid; The segmented premixing method comprises: uniformly mixing chlorinated polyvinyl chloride resin, organic tin main stabilizer, auxiliary stabilizer, lubricating agent, impact modifier, processing aid, foaming agent K500 and filler, heating to 110-120° C., adding the first foaming system, stopping heating and heat preservation, continuously mixing and cooling to 60° C., adding the second foaming system, uniformly mixing, cooling and obtaining a premix; The premix is ​​prepared into a raw material and foamed to obtain a rigid chlorinated polyvinyl chloride foam material.

2. The method for preparing the rigid chlorinated polyvinyl chloride foam material according to claim 1, characterized in that: In the staged premix, 100 parts of chlorinated polyvinyl chloride resin, 2.5-8 parts of composite foaming agent system, 2-3.5 parts of organic tin main stabilizer, 1.5-3 parts of auxiliary stabilizer, 5-9.5 parts of impact modifier, 3.5-8 parts of lubricating aid, 3-5 parts of processing aid, and 1-3.5 parts of filler; The composite foaming agent system consists of a first foaming agent system, a second foaming agent system, and a foaming aid K500; the weight ratio of the first foaming agent system, the second foaming agent system, and the foaming aid K500 is 1.7-2.3:1:0.8-2.

2.

3. The method for preparing the rigid chlorinated polyvinyl chloride foam material according to claim 1, characterized in that: In the preparation of the first foaming system, the mixed solvent consists of acetonitrile and dimethyl sulfoxide, and the mass ratio of acetonitrile to dimethyl sulfoxide is 1:0.2-0.3; The mass ratio of the main foaming agent azodicarbonamide to the mixed solvent is 2-3:

4.

4. The method for preparing the rigid chlorinated polyvinyl chloride foam material according to claim 1, characterized in that: In the preparation of the first foaming system, the zinc oxide is common zinc oxide with an average particle size of 4-10 μm, and / or ultrafine zinc oxide with an average particle size of 0.5-3 μm; The average particle size of zinc stearate is 10-15 μm; The weight ratio of the main foaming agent azodicarbonamide, zinc oxide and zinc stearate is 0.48-1.8:0.08-0.25:0.48-1.

9.

5. The method for preparing the rigid chlorinated polyvinyl chloride foam material according to claim 1, characterized in that: In the preparation of the second foaming system, the particle size specification of the auxiliary foaming agent sodium bicarbonate is not less than 1000 mesh; The weight ratio of the auxiliary foaming agent sodium bicarbonate to the foaming aid is 0.36-1.65:0.1-0.

6.

6. The method for preparing the rigid chlorinated polyvinyl chloride foam material according to claim 1, characterized in that: In the staged premixing, the chlorine content of the chlorinated polyvinyl chloride resin is 61-65wt%, and the melt viscosity is 1600-2400 Pa·s; The main organic tin stabilizer is at least one of the following: methyl tin mercaptan, butyl tin mercaptan, butyl tin laurate, butyl tin maleate; The auxiliary stabilizer is at least one of the following: antioxidant 1010, antioxidant 1076, antioxidant 1500, phosphite, hydrotalcite, and epoxidized soybean oil with an epoxy value of ≥6%.

7. The method for preparing the rigid chlorinated polyvinyl chloride foam material according to claim 1, characterized in that: In the segmented premixing, the lubricating aid is at least one of the following: paraffin, polyethylene wax, oxidized polyethylene wax, chlorinated paraffin, lubricant DOP, lubricant DINP, fatty acid ester G32; The impact modifier is at least one of the following: methacrylate impact modifier, methyl methacrylate / butadiene / styrene copolymer, chlorinated polyethylene, acrylonitrile / butadiene / styrene copolymer; The processing aid is at least one of the following: acrylic processing aid, processing aid LPN20, processing aid LPN80, processing aid 3316; The filler is at least one of the following: titanium dioxide, nano calcium carbonate, and talcum powder.

8. The method for preparing the rigid chlorinated polyvinyl chloride foam material according to claim 1, characterized in that: The method for preparing the embryo material is as follows: placing the premix in an open mill, controlling the processing roller temperature to be 170-175° C., and obtaining the embryo material; The foaming molding method comprises placing the material blank in a pressure molding machine, controlling the molding temperature to be 180° C., and foaming and molding to obtain the rigid chlorinated polyvinyl chloride foaming material.

9. A rigid chlorinated polyvinyl chloride foam material, characterized in that: The method is prepared by the method according to any one of claims 1 to 8.

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