PVC-based composite co-extrusion foamed sheet and preparation method thereof

Abstract

The invention relates to the technical field of polyvinyl chloride foam boards, in particular to a PVC-based composite co-extrusion foam board and a preparation method thereof.The PVC-based composite co-extrusion foam board is composed of a soft layer component and a hard layer component, the soft layer is made of high-polymerization PVC resin which is long in molecular chain and good in flexibility, and the hard layer is made of high-polymerization PVC resin; certain toughness and impact resistance can be provided for the board, the hard layer is made of low-polymerization PVC resin, relatively short in molecular chain and high in hardness, the board is endowed with good rigidity and bearing capacity, the hard layer and the soft layer are combined through a co-extrusion process, the soft layer can buffer external impact force, and the hard layer provides support, so that the board is not prone to deformation and damage when subjected to external force; the overall mechanical property is obviously improved; secondly, by adding the modified fumed silica, the coated nano magnesium oxide and the modified titanium dioxide, the mechanical property of the plate can be improved, for example, the modified fumed silica can be uniformly dispersed in a soft layer component, and the space between resin molecular chains can be filled with the nano-scale particle size of the modified fumed silica.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyvinyl chloride foamed sheet, in particular to a composite co-extrusion foamed sheet based on PVC and a preparation method thereof. BACKGROUND

[0002] As one of the five general-purpose plastics, polyvinyl chloride (PVC) is widely used in construction, packaging, transportation and other fields due to its low cost, excellent chemical corrosion resistance and processing performance. However, traditional PVC sheet has defects such as high density, poor thermal insulation performance and insufficient flame retardancy, especially in the field of building insulation and fire safety, which is difficult to meet the requirements. At present, although the PVC foamed sheet on the market realizes lightweight by adding chemical foaming agent or physical foaming agent, it generally faces the problems of uneven foaming structure and low closed cell rate, which leads to a significant decrease in the mechanical properties of the material. In addition, although the limiting oxygen index of single PVC substrate is higher than that of most polymers, it is still prone to produce melt dripping and toxic smoke under high temperature or continuous fire source, which limits its application in high safety standard fields such as high-rise buildings and rail transit. In the prior art, although the addition of inorganic flame retardants (such as aluminum hydroxide and antimony trioxide) or phosphorus-based flame retardants can improve the flame retardancy, it often comes at the cost of sacrificing material toughness or increasing density, and it is difficult to balance the stability of the foaming process, resulting in an unbalanced comprehensive performance of the product.

[0003] To overcome the above-mentioned defects, co-extrusion molding technology has gradually become a research hotspot for PVC sheet modification due to its advantages of realizing multi-layer material compounding and functional gradient distribution. However, traditional co-extrusion process mainly focuses on surface modification, such as wear-resistant layer and UV-resistant layer, and there are still technical bottlenecks in the synergistic optimization of internal foaming structure and flame retardancy. Therefore, developing a PVC composite co-extrusion foamed sheet with excellent flame retardancy and mechanical stability, and realizing the synergistic effect of the performance of each component through process innovation, has become a key problem to be solved in the industry. SUMMARY

[0004] Technical problems to be solved In view of the above-mentioned defects existing in the prior art, the present application provides a composite co-extrusion foamed sheet based on PVC and a preparation method thereof, which can effectively solve the problems of high density, poor thermal insulation performance and insufficient flame retardancy of the traditional PVC sheet in the prior art.

[0005] Technical scheme To achieve the above-mentioned purposes, the present application is implemented by the following technical scheme: A composite co-extrusion foamed sheet based on PVC, which is composed of a soft layer component and a hard layer component. The soft layer component is composed of the following raw materials: high polymer PVC resin, 4,4'-oxobis benzene sulfonyl hydrazine, glyceryl stabilizer, modified fumed silica, coated nano magnesium hydroxide, modified titanium dioxide and paraffin wax; The hard layer component is composed of the following raw materials: low polymer PVC resin, azodicarbonamide, zinc stearate, glyceryl stabilizer, coated nano magnesium hydroxide, modified titanium dioxide, activated fly ash, plasticizer and paraffin wax.

[0006] Further, the preparation steps of the glyceryl stabilizer are: Step 2.1, 4-5g glyceryl monostearate, 1-2g polyethylene wax and 4-5g oxidized polyethylene wax are added into a flask, after heating and melting, 3-4g zinc oxide, 0.4-0.5g magnesium oxide, 0.8-0.9g calcium hydroxide, 0.5-0.6g acetic acid and 6-7g glycerol are added, and the obtained is recorded as a mixed component; Step 2.2, the mixed component is heated and stirred at a speed of 400-500r / min under nitrogen protection until the temperature reaches 130-140℃, after constant temperature reaction for 3-4h, 10g zinc stearate is added, then 4-5g hydrotalcite and 5-6g secco powder are added, and the obtained is the glyceryl stabilizer after stirring at a speed of 300-400r / min for 10min.

[0007] Further, the preparation steps of the modified fumed silica are: Step 3.1, 3-4g of the dried fumed silica is added into 90-100mL of anhydrous ethanol, and ultrasonic dispersion is carried out, and the obtained is recorded as a dispersion component, 15-18mL of silane coupling agent KH-570 is dispersed in 30-35mL of deionized water, and the obtained is recorded as a silane coupling agent component after sufficient stirring; Step 3.2, the dispersion component and the silane coupling agent component are poured into a flask, stirred at a speed of 300-400r / min at room temperature for 30min, then heated to 70℃ and constant temperature stirring for 3h, after the reaction is completed, centrifuged at a speed of 5000r / min for 5min, and the obtained is recorded as a precipitated product; Step 3.3, the precipitated product is added with a washing liquid and centrifuged for 3 times, and finally placed in a vacuum drying box at 100℃ for vacuum drying for 3h, and the obtained is the modified fumed silica.

[0008] Further, the drying method in step 3.1 is to place in a vacuum drying box at 100℃ for vacuum drying for 3h, the ultrasonic dispersion method in step 3.1 is to ultrasonic dispersion for 30min at a frequency of 40kHz, the sufficient stirring method in step 3.1 is to stir for 20min at a speed of 500-600r / min, and the washing liquid in step 3.3 is an ethanol aqueous solution with a mass fraction of 50%.

[0009] Furthermore, the preparation steps of the coated nano-magnesium hydroxide are as follows: Step 5.1: Weigh 4-5g of nano magnesium hydroxide, 60-62g of urea and 150mL of deionized water into a flask, stir and mix at 50℃, and the mixture after ultrasonic dispersion is recorded as the magnesium hydroxide component. Step 5.2: Weigh 8-9g of zinc oxide, 39-40g of potassium hydroxide, 26-27g of sodium hydroxystannate, and 350mL of deionized water into another flask. Heat to 50℃, then add the magnesium hydroxide component. Continue heating to 85℃ and react at a constant temperature for 6 hours. After filtration, azeotropically distill the filter cake with n-butanol. The resulting powder, after drying, is the coated nano magnesium hydroxide.

[0010] Furthermore, the mixing method in step 5.1 is to stir at a speed of 400-500 r / min for 10 min, the ultrasonic dispersion method in step 5.1 is to ultrasonically disperse at a frequency of 40 kHz for 30 min, and the drying method in step 5.2 is to dry in a vacuum drying oven at 50℃ for 12 h.

[0011] Furthermore, the method for preparing the modified titanium dioxide is as follows: Weigh 18-20g of nano titanium dioxide and 1-2g of silane coupling agent KH-570 and mix them. Stir at 200-300r / min for 10min to obtain modified titanium dioxide.

[0012] Furthermore, the method for preparing the activated fly ash is as follows: The fly ash was dried in a drying oven at 120℃ for 4 hours. Then, the dried fly ash and stearic acid were poured into a high-speed mixer at a weight ratio of 100:1. The mixture was heated to 60℃ at a speed of 800-1000 r / min and mixed for another 30 minutes to obtain activated fly ash.

[0013] A method for preparing a PVC-based composite co-extruded foamed board, the method comprising: S1. Weigh 100 parts by weight of high polymer PVC resin, 0.2-0.3 parts of 4,4'-oxobisbenzenesulfonyl hydrazine, 6-7 parts of glycerol-based stabilizer, 4-5 parts of modified fumed silica, 3-4 parts of coated nano magnesium hydroxide, 2-3 parts of modified titanium dioxide, and 0.2-0.3 parts of paraffin wax, and pour them into an internal mixer for internal mixing. The result is the soft layer component. S2, 100 parts of low polymerization PVC resin, 0.2-0.3 parts of azobisformamide, 0.1-0.2 parts of zinc stearate, 6-7 parts of glyceryl stabilizer, 3-5 parts of coated nano magnesium hydroxide, 2-3 parts of modified titanium dioxide, 1-2 parts of activated fly ash, 40-50 parts of plasticizer and 0.2-0.3 parts of paraffin wax are weighed by weight parts and poured into an internal mixer for internal mixing treatment, and the obtained is the hard layer component; S3, the soft layer component and the hard layer component are poured into different extruders, extruded through a co-extrusion die, and the obtained is the PVC-based composite co-extrusion foam plate after traction setting and cutting.

[0014] Further, the internal mixing treatment method in S1 is internal mixing for 10 min at a temperature of 165 DEG C and a rotation speed of 400-500 r / min, and the internal mixing treatment method in S2 is internal mixing for 10 min at a temperature of 150 DEG C and a rotation speed of 400-500 r / min; the extrusion temperatures of the soft layer component are 150 DEG C, 160 DEG C, 180 DEG C, 180 DEG C and 170 DEG C respectively, and the extrusion temperatures of the hard layer component are 150 DEG C, 165 DEG C, 175 DEG C, 180 DEG C and 175 DEG C respectively.

[0015] Beneficial effects The application provides a PVC-based composite co-extrusion foam plate and a preparation method thereof. 1、The PVC-based composite co-extrusion foam plate in the application is composed of a soft layer component and a hard layer component, the soft layer adopts high polymerization PVC resin, the molecular chain of which is long and flexible, and can provide certain toughness and impact resistance for the plate, the hard layer uses low polymerization PVC resin, the molecular chain of which is relatively short and has high hardness, and can give the plate good rigidity and load bearing capacity, the two are combined through a co-extrusion process, the soft layer can buffer external impact force, and the hard layer can provide support, so that the plate is not easy to deform and damage when subjected to external force, and the overall mechanical property is significantly improved; secondly, the addition of modified fumed silica, coated nano magnesium oxide and modified titanium dioxide can improve the mechanical property of the plate, for example, the modified fumed silica can be uniformly dispersed in the soft layer component, the nano-sized particle diameter of which can be filled between the resin molecular chains, forming physical crosslinking points to limit the movement of the molecular chains, thereby improving the strength and hardness of the plate; the nano magnesium oxide is treated by special coating, and the interfacial bonding force with the PVC resin is enhanced, which can effectively transfer stress and prevent crack propagation when subjected to stress, thereby enhancing the anti-fracture capacity of the plate, and the high specific surface area can increase the contact area with the resin, thereby further improving the mechanical property; the modified titanium dioxide by silane coupling agent KH-570 has improved compatibility with the PVC resin, and can be uniformly dispersed in the plate to play a role in strengthening and toughening, and form a more compact structure with the resin, thereby improving the overall mechanical property of the plate.

[0016] 2、4,4'-oxybisbenzenesulfonylhydrazide in the soft layer component and azodicarbonamide in the hard layer component are both foaming agents, under the condition of heating, they decompose to produce a large amount of gas, form bubble nucleus in the PVC resin, with the continuous production and diffusion of the gas, the bubble gradually grows, thus the board forms a porous foaming structure, this foaming structure can reduce the density of the board, reduce the weight, at the same time, it can also play a role in heat insulation and sound insulation; secondly, the glyceryl stabilizer can play a key role in the foaming process, it can keep the stability of the PVC resin at high temperature, prevent its decomposition, ensure the smooth progress of the foaming process, at the same time, the stabilizer can adjust the diffusion speed of the foaming gas, make the bubble evenly distributed, avoid the problems of too large or too small bubble, uneven distribution, etc., thus obtain good foaming effect; further, the various components in the glyceryl stabilizer synergize with each other, together improve the thermal stability of the board, for example, zinc oxide, magnesium oxide and calcium hydroxide and other components can occur complex chemical reactions, form stable complex, effectively capture the hydrogen chloride gas produced by the decomposition of the PVC resin, prevent its catalytic decomposition of the resin, thus ensure the performance stability of the board at high temperature.

[0017] 3、The coated nano-magnesium hydroxide and activated fly ash in the application both have certain flame retardant effect, the nano-magnesium hydroxide can decompose and absorb heat at high temperature, reduce the temperature of the surrounding environment, at the same time, release the non-combustible gas, dilute the oxygen concentration in the air, inhibit the combustion, the activated fly ash contains various inorganic components, such as silicon dioxide, aluminum oxide, etc., they have high thermal stability and non-combustibility, can form a protective film on the surface of the board, prevent the spread of the flame, improve the flame retardant performance of the board; secondly, the coated nano-magnesium hydroxide and activated fly ash cooperate with other components to form a synergistic flame retardant system, for example, the gas produced by the decomposition of the nano-magnesium hydroxide can promote the dispersion and adhesion of the activated fly ash on the surface of the board, enhance the compactness and stability of the protective film, while the existence of the activated fly ash can provide more adhesion points for the nano-magnesium hydroxide, improve its flame retardant efficiency, thus significantly improve the flame retardant performance of the board.

[0018] 4. The modified titanium dioxide in this invention has excellent ultraviolet absorption and shielding properties. In outdoor environments, ultraviolet radiation is one of the main factors causing the aging of PVC sheets. Modified titanium dioxide can absorb or reflect ultraviolet radiation, reducing the exposure of PVC resin to ultraviolet radiation, reducing the breakage of resin molecular chains and oxidation reactions, thereby delaying the aging process of the sheets and improving their weather resistance. Moreover, the various components in the glycerol-based stabilizer can work synergistically to inhibit the photo-oxidation and thermal oxidation reactions of PVC resin. For example, components such as acetic acid can react with free radicals generated by resin decomposition, terminating the free radical chain reaction and preventing further degradation of the resin. Components such as metal oxides can absorb ultraviolet radiation, reducing its damage to the resin, thereby enhancing the anti-aging performance of the sheets. Finally, when preparing the soft layer and hard layer components, an internal mixer is used for internal mixing. The high-speed rotation and strong shear force of the internal mixer can fully mix the raw materials, ensuring that the modified fumed silica, coated nano-magnesium oxide, modified titanium dioxide, and other additives are uniformly dispersed in the PVC resin. Uniform mixing helps to fully utilize the performance of each component and improve the quality stability of the sheets. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0020] The present invention will be further described below with reference to embodiments.

[0021] The sources of some components in the examples and comparative examples are as follows: High-polymer PVC resin, PVC2500, Tianjin Bohai Chemical Plant; Low-polymer PVC resin, PVCSG-7, Tianjin Bohai Chemical Plant; 4,4'-Oxobisbenzenesulfonylhydrazine, Shandong Qiangsen Chemical Co., Ltd.; Azodicarbonamide, Jinan Weite Chemical Technology Co., Ltd.; Zinc stearate, Langfang Qianyao Technology Co., Ltd.; Glyceryl monostearate, Hangzhou Oil & Fat Chemical Co., Ltd.; Polyethylene wax, Wuhan Xindongyi Chemical Co., Ltd.; Oxidized polyethylene wax, Jinan Yuyi Chemical Co., Ltd.; Zinc oxide, Weifang Aoda Zinc Industry Co., Ltd.; Magnesium oxide, Wuxi Zehui Chemical Co., Ltd.; Calcium hydroxide, Nanjing Gehao Environmental Protection Technology Co., Ltd. Acetic acid, Shandong Tenghua New Material Co., Ltd. Glycerol, Taixing Borun Chemical Co., Ltd. Hydrotalcite, Shijiazhuang Baijiang Mining Products Co., Ltd. Sic powder, Jinan Zian Chemical Co., Ltd. Fumed silica, Nanometer grade, Primary particle size 7-40 nm, Shanghai Aladdin Biochemical Technology Co., Ltd. Silane coupling agent KH-570, Shanghai Aladdin Biochemical Technology Co., Ltd. Nanometer titanium dioxide, Hebei Canri Chemical Co., Ltd.

[0022] Example 1 A PVC-based composite co-extrusion foaming plate according to the present embodiment is composed of a soft layer component and a hard layer component. The soft layer component is composed of the following raw materials: high polymerization PVC resin, 4,4'-oxobenzene sulfonyl hydrazine, glycerol-based stabilizer, modified fumed silica, coated nanometer magnesium hydroxide, modified titanium dioxide and paraffin wax. The hard layer component is composed of the following raw materials: low polymerization PVC resin, azodicarbonamide, zinc stearate, glycerol-based stabilizer, coated nanometer magnesium hydroxide, modified titanium dioxide, activated fly ash, plasticizer and paraffin wax.

[0023] The preparation steps of the glycerol-based stabilizer are as follows: Step 2.1, 4g glycerol monostearate, 1g polyethylene wax and 4g oxidized polyethylene wax were added to a flask, and after being heated and melted, 3g zinc oxide, 0.4g magnesium oxide, 0.8g calcium hydroxide, 0.5g acetic acid and 6g glycerol were added, and the obtained mixture was denoted as a mixed component; Step 2.2, the mixed component was heated and stirred at a speed of 400r / min under nitrogen protection until the temperature reached 130℃, and after constant temperature reaction for 3h, 10g zinc stearate was added, followed by 4g hydrotalcite and 5g sic powder, and after stirring at a speed of 300r / min for 10min, the obtained product was the glycerol-based stabilizer.

[0024] The preparation steps of the modified fumed silica are as follows: Step 3.1, 3g fumed silica dried in a vacuum drying box at 100℃ for 3h was added to 90mL anhydrous ethanol, and ultrasonic dispersion was carried out at a frequency of 40kHz for 30min to obtain a dispersed component, and 15mL silane coupling agent KH-570 was dispersed in 30mL deionized water, and stirring was carried out at a speed of 500r / min for 20min to obtain a silane coupling agent component; Step 3.2, pour the dispersion component and the silane coupling agent component into a flask, stir at a speed of 300 r / min at room temperature for 30 min, then heat to 70℃ and stir at constant temperature for 3 h, after the reaction is completed, centrifuge at a speed of 5000 r / min for 5 min, and the obtained is recorded as the precipitate product; Step 3.3, add 50% mass fraction of ethanol aqueous solution to the precipitate product and centrifuge for washing 3 times, and finally place in a vacuum drying oven at 100℃ for vacuum drying for 3 h, and the obtained is the modified fumed silica.

[0025] The preparation steps of the coated nano magnesium hydroxide are as follows: Step 5.1, weigh 4 g of nano magnesium hydroxide, 60 g of urea and 150 mL of deionized water into a flask, stir at a speed of 400 r / min at a temperature of 50℃ for 10 min, and then ultrasonic dispersion at a frequency of 40 kHz for 30 min, and the obtained is recorded as the magnesium hydroxide component; Step 5.2, weigh 8 g of zinc oxide, 39 g of potassium hydroxide and 26 g of sodium hydroxystannate and 350 mL of deionized water into another flask, heat to 50℃, then pour into the magnesium hydroxide component, continue to heat to 85℃, and then constant temperature reaction for 6 h, after filtration, the filter cake is co-distilled with n-butanol, and the obtained powder is dried by placing in a vacuum drying oven at 50℃ for 12 h to obtain the coated nano magnesium hydroxide.

[0026] The preparation method of the modified titanium dioxide is as follows: Weigh 18 g of nano titanium dioxide and 1 g of silane coupling agent KH-570 for mixing, stir at a speed of 200 r / min for 10 min, and the obtained is the modified titanium dioxide.

[0027] The preparation method of the activated fly ash is as follows: Place the fly ash in a drying oven at 120℃ for 4 h, then pour the dried fly ash and stearic acid into a high-speed mixer at a weight ratio of 100:1, heat to 60℃ at a speed of 800 r / min, continue to mix for 30 min, and the obtained is the activated fly ash.

[0028] A preparation method of a composite co-extrusion foamed plate based on PVC, the preparation method is as follows: S1, weigh 100 parts of high polymer PVC resin, 0.2 parts of 4,4'-oxobenzene sulfonyl hydrazine, 6 parts of glyceryl stabilizer, 4 parts of modified fumed silica, 3 parts of coated nano magnesium hydroxide, 2 parts of modified titanium dioxide and 0.2 parts of paraffin into an internal mixer for internal mixing treatment, and the obtained is the soft layer component; S2, 100 parts of low polymerization PVC resin, 0.2 parts of azobisformamide, 0.1 parts of zinc stearate, 6 parts of glyceryl stabilizer, 3 parts of coated nano magnesium hydroxide, 2 parts of modified titanium dioxide, 1 part of activated fly ash, 40 parts of plasticizer and 0.2 parts of paraffin wax are weighed by weight parts and poured into an internal mixer for internal mixing treatment, and the obtained is the hard layer component; S3, the soft layer component and the hard layer component are poured into different extruders, extruded through a co-extrusion die, and the obtained is the PVC-based composite co-extrusion foam sheet after traction setting and cutting.

[0029] The method of internal mixing treatment in S1 is internal mixing at a temperature of 165℃ and a speed of 400r / min for 10min, and the method of internal mixing treatment in S2 is internal mixing at a temperature of 150℃ and a speed of 400r / min for 10min; the extrusion temperatures of the soft layer component are 150℃, 160℃, 180℃, 180℃ and 170℃ respectively, and the extrusion temperatures of the hard layer component are 150℃, 165℃, 175℃, 180℃ and 175℃ respectively.

[0030] Example 2 The PVC-based composite co-extrusion foam sheet of the present embodiment is composed of a soft layer component and a hard layer component; The soft layer component is composed of the following raw materials: high polymerization PVC resin, 4,4'-oxobisbenzenesulfonyl hydrazide, glyceryl stabilizer, modified fumed silica, coated nano magnesium hydroxide, modified titanium dioxide and paraffin wax; The hard layer component is composed of the following raw materials: low polymerization PVC resin, azobisformamide, zinc stearate, glyceryl stabilizer, coated nano magnesium hydroxide, modified titanium dioxide, activated fly ash, plasticizer and paraffin wax.

[0031] The preparation steps of the glyceryl stabilizer are as follows: Step 2.1, 5g of glyceryl monostearate, 2g of polyethylene wax and 5g of oxidized polyethylene wax are added to a flask, heated and melted, then 4g of zinc oxide, 0.5g of magnesium oxide, 0.9g of calcium hydroxide, 0.6g of acetic acid and 7g of glycerol are added, and the obtained is marked as a mixed component; Step 2.2, the mixed component is stirred and heated under nitrogen protection at a speed of 500r / min to 140℃, and after constant temperature reaction for 4h, 10g of zinc stearate is added, then 5g of hydrotalcite and 6g of secco powder are added, and the obtained is the glyceryl stabilizer after stirring at a speed of 400r / min for 10min.

[0032] The preparation steps of the modified fumed silica are as follows: Step 3.1, 4g of fumed silica dried in a vacuum drying oven at 100℃ for 3h was weighed and added into 100mL of anhydrous ethanol, and dispersed by ultrasonic at a frequency of 40kHz for 30min, and the obtained product was recorded as a dispersion component; 18mL of silane coupling agent KH-570 was dispersed in 35mL of deionized water, and stirred at a speed of 600r / min for 20min, and the obtained product was recorded as a silane coupling agent component; Step 3.2, the dispersion component and the silane coupling agent component were poured into a flask, stirred at a speed of 400r / min at room temperature for 30min, heated to 70℃ and stirred for 3h, and after the reaction was completed, centrifuged at a speed of 5000r / min for 5min, and the obtained product was recorded as a precipitated product; Step 3.3, the precipitated product was added with an ethanol aqueous solution with a mass fraction of 50%, and centrifuged for 3 times, and finally dried in a vacuum drying oven at 100℃ for 3h, and the obtained product was modified fumed silica.

[0033] The preparation steps of the coated nano magnesium hydroxide are as follows: Step 5.1, 5g of nano magnesium hydroxide, 62g of urea and 150mL of deionized water were weighed and poured into a flask, stirred at a speed of 500r / min at a temperature of 50℃ for 10min, and dispersed by ultrasonic at a frequency of 40kHz for 30min, and the obtained product was recorded as a magnesium hydroxide component; Step 5.2, 9g of zinc oxide, 40g of potassium hydroxide and 27g of sodium hydroxystannate were weighed and poured into another flask, heated to 50℃, poured into the magnesium hydroxide component, and heated to 85℃, and then reacted at a constant temperature for 6h, and after filtration, the filter cake was azeotropically distilled with n-butanol, and the dried powder was placed in a vacuum drying oven at 50℃ for 12h to obtain the coated nano magnesium hydroxide.

[0034] The preparation method of the modified titanium dioxide is as follows: 20g of nano titanium dioxide and 2g of silane coupling agent KH-570 were weighed and mixed, and stirred at a speed of 300r / min for 10min, and the obtained product was recorded as modified titanium dioxide.

[0035] The preparation method of the activated fly ash is as follows: The fly ash was placed in a drying oven at 120℃ for 4h, and then the dried fly ash and stearic acid were poured into a high-speed mixer at a weight ratio of 100:1, heated to 60℃ at a speed of 1000r / min, and then mixed for 30min, and the obtained product was recorded as activated fly ash.

[0036] A preparation method of a composite co-extrusion foamed plate based on PVC, the preparation method is as follows: S1, 100 parts of high polymerization PVC resin, 0.3 parts of 4, 4'-oxobisbenzenesulfonyl hydrazide, 7 parts of glyceryl stabilizer, 5 parts of modified fumed silica, 4 parts of coated nano magnesium hydroxide, 3 parts of modified titanium dioxide and 0.3 parts of paraffin wax are weighed by weight parts and poured into an internal mixer for internal mixing treatment, and the obtained is the soft layer component; S2, 100 parts of low polymerization PVC resin, 0.3 parts of azobisformamide, 0.2 parts of zinc stearate, 7 parts of glyceryl stabilizer, 5 parts of coated nano magnesium hydroxide, 3 parts of modified titanium dioxide, 2 parts of activated fly ash, 50 parts of plasticizer and 0.3 parts of paraffin wax are weighed by weight parts and poured into an internal mixer for internal mixing treatment, and the obtained is the hard layer component; S3, the soft layer component and the hard layer component are poured into different extruders and extruded through a co-extrusion die, and the obtained is a PVC-based composite co-extrusion foam sheet after traction shaping and cutting.

[0037] Among them, the internal mixing treatment method in S1 is internal mixing at a temperature of 165℃ and a speed of 500r / min for 10min, and the internal mixing treatment method in S2 is internal mixing at a temperature of 150℃ and a speed of 500r / min for 10min; the extrusion temperature of the soft layer component is 150℃, 160℃, 180℃, 180℃ and 170℃ respectively, and the extrusion temperature of the hard layer component is 150℃, 165℃, 175℃, 180℃ and 175℃ respectively.

[0038] Example 3 A PVC-based composite co-extrusion foam sheet according to the present embodiment is composed of a soft layer component and a hard layer component; The soft layer component is composed of the following raw materials: high polymerization PVC resin, 4, 4'-oxobisbenzenesulfonyl hydrazide, glyceryl stabilizer, modified fumed silica, coated nano magnesium hydroxide, modified titanium dioxide and paraffin wax; The hard layer component is composed of the following raw materials: low polymerization PVC resin, azobisformamide, zinc stearate, glyceryl stabilizer, coated nano magnesium hydroxide, modified titanium dioxide, activated fly ash, plasticizer and paraffin wax.

[0039] The preparation steps of the glyceryl stabilizer are as follows: Step 2.1, 5g of glyceryl monostearate, 2g of polyethylene wax and 5g of oxidized polyethylene wax are added to a flask, and after heating and melting, 4g of zinc oxide, 0.4g of magnesium oxide, 0.9g of calcium hydroxide, 0.6g of acetic acid and 7g of glycerol are added, and the obtained is marked as a mixed component; Step 2.2, under the protection of nitrogen, the mixed components were heated to 135℃ at a stirring speed of 500r / min, after 4h of constant temperature reaction, 10g of zinc stearate was added, then 5g of hydrotalcite and 6g of secco powder were added, after 10min of stirring at a speed of 400r / min, the obtained product was glyceryl stabilizer.

[0040] The preparation steps of modified fumed silica are: Step 3.1, 4g of fumed silica dried in a vacuum drying oven at 100℃ for 3h was added into 95mL of anhydrous ethanol, and ultrasonic dispersion was carried out at a frequency of 40kHz for 30min, then the obtained product was recorded as dispersion component, 16mL of silane coupling agent KH-570 was dispersed in 33mL of deionized water, and stirring was carried out at a speed of 600r / min for 20min, then the obtained product was recorded as silane coupling agent component; Step 3.2, the dispersion component and the silane coupling agent component were poured into a flask, and after 30min of constant temperature stirring at a speed of 400r / min, heating was carried out to 70℃ and constant temperature stirring was carried out for 3h, after the reaction was completed, centrifugation was carried out at a speed of 5000r / min for 5min, and the obtained product was recorded as precipitation product; Step 3.3, the precipitation product was added with 50% ethanol aqueous solution, and centrifugal washing was carried out for 3 times, finally, it was placed in a vacuum drying oven at 100℃ for 3h of vacuum drying, and the obtained product was modified fumed silica.

[0041] The preparation steps of coated nano magnesium hydroxide are: Step 5.1, 5g of nano magnesium hydroxide, 61g of urea and 150mL of deionized water were weighed and poured into a flask, stirring was carried out at a speed of 500r / min at a temperature of 50℃ for 10min, and ultrasonic dispersion was carried out at a frequency of 40kHz for 30min, then the obtained product was recorded as magnesium hydroxide component; Step 5.2, 9g of zinc oxide, 40g of potassium hydroxide and 27g of sodium hydroxystannate and 350mL of deionized water were weighed and poured into another flask, after heating to 50℃, it was poured into the magnesium hydroxide component, and after continuous heating to 85℃, constant temperature reaction was carried out for 6h, after filtration, the filter cake was subjected to azeotropic distillation with n-butanol, and the obtained powder was dried by placing it in a vacuum drying oven at 50℃ for 12h, and the obtained product was coated nano magnesium hydroxide.

[0042] The preparation method of modified titanium dioxide is: 19g of nano titanium dioxide and 2g of silane coupling agent KH-570 were weighed and mixed, and stirring was carried out at a speed of 300r / min for 10min, and the obtained product was modified titanium dioxide.

[0043] The preparation method of activated fly ash is: The fly ash is placed in a drying oven at 120 DEG C for 4h, then the dried fly ash and stearic acid are poured into a high-speed mixer at a weight ratio of 100:1, heated to 60 DEG C at a rotation speed of 900r / min, and mixed for 30min to obtain the activated fly ash.

[0044] A preparation method of a PVC-based composite co-extrusion foamed plate, the preparation method comprises the following steps: S1, 100 parts of high polymerization PVC resin, 0.3 parts of 4,4'-oxobenzene sulfonyl hydrazine, 7 parts of glyceryl stabilizer, 5 parts of modified fumed silica, 4 parts of coated nano magnesium hydroxide, 2 parts of modified titanium dioxide and 0.3 parts of paraffin wax are weighed according to the weight parts and poured into an internal mixer for internal mixing treatment, and the obtained product is a soft layer component; S2, 100 parts of low polymerization PVC resin, 0.3 parts of azobenzene, 0.2 parts of zinc stearate, 7 parts of glyceryl stabilizer, 4 parts of coated nano magnesium hydroxide, 3 parts of modified titanium dioxide, 2 parts of activated fly ash, 45 parts of plasticizer and 0.3 parts of paraffin wax are weighed according to the weight parts and poured into an internal mixer for internal mixing treatment, and the obtained product is a hard layer component; S3, the soft layer component and the hard layer component are poured into different extruders and extruded through a co-extrusion die, and then cut after traction and shaping to obtain a PVC-based composite co-extrusion foamed plate.

[0045] In S1, the internal mixing treatment method is internal mixing at a rotation speed of 500r / min for 10min at a temperature of 165 DEG C, and in S2, the internal mixing treatment method is internal mixing at a rotation speed of 400r / min for 10min at a temperature of 150 DEG C; the extrusion temperatures of the soft layer component are 150 DEG C, 160 DEG C, 180 DEG C, 180 DEG C and 170 DEG C respectively, and the extrusion temperatures of the hard layer component are 150 DEG C, 165 DEG C, 175 DEG C, 180 DEG C and 175 DEG C respectively.

[0046] Comparative Example 1 The PVC-based composite co-extrusion foamed plate and the preparation method thereof provided by the comparative example are basically the same as those of Example 1, and the main difference is that the glyceryl stabilizer in Example 1 is replaced by a commercially available stabilizer.

[0047] Comparative Example 2 The PVC-based composite co-extrusion foamed plate and the preparation method thereof provided by the comparative example are basically the same as those of Example 1, and the main difference is that the coated nano magnesium hydroxide in Example 1 is replaced by magnesium hydroxide.

[0048] Comparative Example 3 The PVC-based composite co-extruded foamed board and its preparation method provided in this comparative example are largely the same as those in Example 1. The main difference is that the modified titanium dioxide in Example 1 is replaced with titanium dioxide in this comparative example.

[0049] Performance testing The PVC-based composite co-extruded foamed boards prepared in Examples 1-3 and Comparative Examples 1-3 were labeled as Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3, respectively. The performance of Examples 1-3 and Comparative Examples 1-3 was then tested, and the data obtained are recorded in the table below. As shown in the table above, the mechanical properties and flame retardant properties of the PVC-based composite co-extruded foamed boards prepared in Examples 1-3 are superior to those of Comparative Examples 1-3, indicating that the PVC-based composite co-extruded foamed boards prepared by the method of the present invention have better promotional value.

[0050] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A PVC-based composite co-extruded foamed board, characterized in that, The PVC-based composite co-extruded foam board consists of a soft layer component and a hard layer component; The soft layer component is composed of the following raw materials: high polymer PVC resin, 4,4'-oxobisbenzenesulfonyl hydrazine, glycerol-based stabilizer, modified fumed silica, coated nano magnesium hydroxide, modified titanium dioxide and paraffin. The hard layer component is composed of the following raw materials: low-polymer PVC resin, azodicarbonamide, zinc stearate, glycerol-based stabilizer, coated nano magnesium hydroxide, modified titanium dioxide, activated fly ash, plasticizer, and paraffin wax.

2. The PVC-based composite co-extruded foamed board according to claim 1, characterized in that, The preparation steps of the glycerol-based stabilizer are as follows: Step 2.1: Add 4-5g of glyceryl monostearate, 1-2g of polyethylene wax and 4-5g of oxidized polyethylene wax to a flask, heat to melt, and then add 3-4g of zinc oxide, 0.4-0.5g of magnesium oxide, 0.8-0.9g of calcium hydroxide, 0.5-0.6g of acetic acid and 6-7g of glycerol. The result is recorded as the mixed component. Step 2.2: Under nitrogen protection, stir and heat the mixed components at a speed of 400-500 r / min to raise the temperature to 130-140℃, and react at a constant temperature for 3-4 hours. Then add 10g of zinc stearate, followed by 4-5g of hydrotalcite and 5-6g of cyproheptad powder. Stir at a speed of 300-400 r / min for 10 minutes to obtain the glycerol-based stabilizer.

3. The PVC-based composite co-extruded foamed board according to claim 1, characterized in that, The preparation steps of the modified fumed silica are as follows: Step 3.1: Weigh 3-4g of dried fumed silica and add it to 90-100mL of anhydrous ethanol. After ultrasonic dispersion, the result is recorded as the dispersion component. Disperse 15-18mL of silane coupling agent KH-570 in 30-35mL of deionized water and stir thoroughly. The result is recorded as the silane coupling agent component. Step 3.2: Pour the dispersion component and the silane coupling agent component into a flask, stir at 300-400 r / min at room temperature for 30 min, then heat to 70℃ and stir at a constant temperature for 3 h. After the reaction is complete, centrifuge at 5000 r / min for 5 min. The result is recorded as the precipitate. Step 3.3: Add washing solution to the precipitate and centrifuge and wash 3 times. Finally, place it in a vacuum drying oven at 100℃ and vacuum dry for 3 hours. The result is modified fumed silica.

4. A PVC-based composite co-extruded foamed board according to claim 3, characterized in that, The drying method in step 3.1 is to place the container in a vacuum drying oven at 100℃ and dry it under vacuum for 3 hours. The ultrasonic dispersion method in step 3.1 is to ultrasonically disperse the container at a frequency of 40kHz for 30 minutes. The thorough stirring method in step 3.1 is to stir the container at a speed of 500-600r / min for 20 minutes. The washing solution in step 3.3 is an aqueous solution of ethanol with a mass fraction of 50%.

5. A PVC-based composite co-extruded foamed board according to claim 1, characterized in that, The preparation steps of the coated nano-magnesium hydroxide are as follows: Step 5.1: Weigh 4-5g of nano magnesium hydroxide, 60-62g of urea and 150mL of deionized water into a flask, stir and mix at 50℃, and the mixture after ultrasonic dispersion is recorded as the magnesium hydroxide component. Step 5.2: Weigh 8-9g of zinc oxide, 39-40g of potassium hydroxide, 26-27g of sodium hydroxystannate, and 350mL of deionized water into another flask. Heat to 50℃, then add the magnesium hydroxide component. Continue heating to 85℃ and react at a constant temperature for 6 hours. After filtration, azeotropically distill the filter cake with n-butanol. The resulting powder, after drying, is the coated nano magnesium hydroxide.

6. A PVC-based composite co-extruded foamed board according to claim 5, characterized in that, The mixing method in step 5.1 is to stir at a speed of 400-500 r / min for 10 min. The ultrasonic dispersion method in step 5.1 is to ultrasonically disperse at a frequency of 40 kHz for 30 min. The drying method in step 5.2 is to dry in a vacuum drying oven at 50℃ for 12 h.

7. A PVC-based composite co-extruded foamed board according to claim 1, characterized in that, The method for preparing the modified titanium dioxide is as follows: Weigh 18-20g of nano titanium dioxide and 1-2g of silane coupling agent KH-570 and mix them. Stir at 200-300r / min for 10min to obtain modified titanium dioxide.

8. A PVC-based composite co-extruded foamed board according to claim 1, characterized in that, The method for preparing the activated fly ash is as follows: The fly ash was dried in a drying oven at 120℃ for 4 hours. Then, the dried fly ash and stearic acid were poured into a high-speed mixer at a weight ratio of 100:

1. The mixture was heated to 60℃ at a speed of 800-1000 r / min and mixed for another 30 minutes to obtain activated fly ash.

9. A method for preparing a PVC-based composite co-extruded foamed board according to any one of claims 1-8, characterized in that, The preparation method is as follows: S1. Weigh 100 parts by weight of high polymer PVC resin, 0.2-0.3 parts of 4,4'-oxobisbenzenesulfonyl hydrazine, 6-7 parts of glycerol-based stabilizer, 4-5 parts of modified fumed silica, 3-4 parts of coated nano magnesium hydroxide, 2-3 parts of modified titanium dioxide, and 0.2-0.3 parts of paraffin wax, and pour them into an internal mixer for internal mixing. The result is the soft layer component. S2. Weigh 100 parts by weight of low-polymer PVC resin, 0.2-0.3 parts of azodicarbonamide, 0.1-0.2 parts of zinc stearate, 6-7 parts of glycerol-based stabilizer, 3-5 parts of coated nano magnesium hydroxide, 2-3 parts of modified titanium dioxide, 1-2 parts of activated fly ash, 40-50 parts of plasticizer, and 0.2-0.3 parts of paraffin wax, and pour them into an internal mixer for internal mixing. The result is the hard layer component. S3. The soft layer component and the hard layer component are poured into different extruders and extruded through a co-extrusion die. After being pulled, shaped and cut, the resulting product is a PVC-based composite co-extruded foam board.

10. A method for preparing a PVC-based composite co-extruded foamed board according to claim 9, characterized in that, The mixing process in S1 is to mix at 165℃ and 400-500 r / min for 10 minutes. The mixing process in S2 is to mix at 150℃ and 400-500 r / min for 10 minutes.

Images