Weather-resistant and high-temperature-resistant PVC modified plastic and preparation method thereof

Abstract

The application belongs to the technical field of PVC plastic plates, and particularly relates to a weather-resistant and high-temperature-resistant PVC modified plastic and a preparation method thereof. The application is a novel thermal crosslinking stabilizer, which is prepared by modifying Zn-Mg-NO3-LDHs with dicyclopentadiene zinc dimethylate salt, has excellent dispersibility and high thermal stability, and can also improve the mechanical properties of PVC plastic. The novel thermal crosslinking stabilizer prepared by the application is added into the formula of PVC plastic, so that the thermal stability and mechanical properties of the PVC plastic are greatly improved, and a weather-resistant and high-temperature-resistant PVC modified plastic is obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of PVC plastic plates, and particularly relates to a weather-resistant and high-temperature-resistant PVC modified plastic and a preparation method thereof. BACKGROUND

[0002] Polyvinyl chloride (PVC) plastic generally refers to an amorphous polymer formed by homopolymerization of a vinyl chloride monomer, which is abbreviated as PVC. The chemical stability of PVC is very high, and PVC can resist any concentration of hydrochloric acid, 90% or less of sulfuric acid, 50%-60% of nitric acid and 20% or less of caustic soda solution at room temperature. PVC plastic is insoluble in water, gasoline, alcohol and vinyl chloride, and soluble in ketones and other ketones, lipids or chloroform solvents. Polyvinyl chloride (PVC) has no obvious melting point, and is in a glass state below 85 DEG C, starts to soften at 80-85 DEG C, is in a viscoelastic state at 85-175 DEG C, becomes leather-like when heated to above 130 DEG C, is in a molten state at 175-190 DEG C, is in a viscous flow state at 190-200 DEG C, starts to flow at 180 DEG C, starts to flow at 145 DEG C under pressure, decomposes at above 170 DEG C, and violently decomposes and turns black at above 200 DEG C. Soft polyvinyl chloride products will become hard at low temperatures. Since polyvinyl chloride contains chlorine atoms, it and its copolymers are generally resistant to burning and flame, have self-extinguishing properties, self-extinguish after leaving the fire, degrade and release HCl, CO and benzene and other low molecular compounds during combustion, and have no dripping property.

[0003] The long-term use temperature of most polyvinyl chloride (PVC) plastic products should not exceed 55 DEG C, but the long-term use temperature of special formula polyvinyl chloride plastic can reach 90 DEG C. Polyvinyl chloride (PVC) plastic is a relatively unstable polymer, which can also be degraded under the action of light and heat, and the process is to release nitrogenization and change the structure, but the degree is relatively light. Meanwhile, the decomposition can be accelerated in the presence of mechanical force, oxygen, odor, HCl and some active metal ions. After the removal of HCl from polyvinyl chloride (PVC) plastic, a conjugated double bond is generated on the main chain, and the color also changes. With the increase of the number of chlorination decomposition, the polyvinyl chloride plastic changes from white to yellow, rose, red, brown and even black.

[0004] In China, the consumption structure of PVC changes rapidly, and the proportion of hard products has increased year by year, accounting for about 55%, and the proportion of soft products accounts for about 45%. The representative 10-year change of soft and hard products in China; According to the forecast of the relevant departments in the region, the fields with rapid growth of PVC consumption in China are the construction industry and the packaging industry. The construction industry is a rapidly growing industry in China in recent years and in the future. The development of the construction industry requires a large amount of chemical building materials, including plastic building materials (plastic pipes, plastic doors and windows, floor materials, wallpaper and sanitary wares), building waterproof materials, thermal insulation materials, building coatings, adhesives, sealing materials and plugging agents. Among them, plastic doors and windows and pipes are used in large quantities, and various plastic insulation boards that replace wood also develop rapidly. PVC pipe production in China began in 1983, when Shenyang Plastic Factory (now the predecessor of Shenyang Jiu Li) was put into production. It developed in the late 1990s, during which time factories with an annual production capacity of more than 50,000 tons were built and put into production. At present, PVC pipes account for about 70% of the market share of plastic pipes. There are more than 400 plastic pipe production enterprises in the country, but only more than 70 enterprises have an annual production capacity of more than 10,000 tons, and more than 20 enterprises have an annual production capacity of more than 30,000 tons, accounting for 60% of the industry's output. At present, the production capacity of pipes and pipe fittings is about 1.2 million tons, and the output has broken through 800,000 tons. After years of promotion and application, the excellent performance and engineering economy of plastic pipes are gradually accepted by people. The promotion and application of hard PVC plastic pipes for building drainage have developed rapidly, and the number of applications has increased rapidly in recent years, covering many provinces, cities and autonomous regions in China. In some economically developed areas, the internal wiring of buildings gradually adopts the method of underground laying, which makes the promotion and application of cold-bent PVC flame-retardant money pipe develop rapidly. The application of hard PVC plastic pipes in urban water supply pipelines is also gradually expanding, and has been used in the water supply pipeline system of many cities and dozens of small towns in China.

[0005] In order to improve the processing performance of plastic and the use performance of products, and broaden the application field of PVC plastic, it is necessary to further enhance the weather resistance and high temperature resistance of PVC plastic. CN 112759861 A discloses a kind of high temperature resistant PVC plastic plate, which greatly improves the high temperature resistance of PVC plastic plate by adding stone powder, white carbon black and paraffin in PVC plastic plate, and avoids the instability of PVC plastic plate when used in high temperature environment. However, the heat stabilizer used is still the traditional organic tin stabilizer, which is high in price and poor in stability. SUMMARY

[0006] In order to achieve the above purpose, the present application provides a kind of weather resistant and high temperature resistant PVC modified plastic and its preparation method.

[0007] A kind of weather resistant and high temperature resistant PVC modified plastic preparation method, including the following steps:

[0008] (1) mixing 90-100 parts by mass of polyvinyl chloride, 10-20 parts of superfine active calcium carbonate, 1-2 parts of calcium stearate, 4-6 parts of thermal crosslinking stabilizer, 5-7 parts of epoxy soybean oil, 10-20 parts of dioctyl phthalate, stirring at a speed of 40-70 r / min and heating at a rate of 10-20 ℃ / min to 100-130 ℃, stopping stirring, cooling to 70-80 ℃, to obtain a preliminary mixture;

[0009] (2) adding the preliminary mixture prepared in step (1) into a twin-screw extruder, melting, mixing, extruding with the twin-screw extruder, and obtaining a crude material after cooling;

[0010] (3) placing the crude material prepared in step (2) into a flat vulcanizing machine, vulcanizing, and obtaining the weather-resistant and high-temperature-resistant PVC modified plastic.

[0011] The parameters of the twin-screw extruder in step (2) are: screw rotation speed 40-60 r / min, conveying section temperature 140-145 ℃, melting section temperature 175-180 ℃, homogenizing section temperature 175-180 ℃, and extrusion melt pressure 26-30 MPa.

[0012] The parameters of the flat vulcanizing machine in step (3) are: upper and lower plate temperature 170-185 ℃, pressure 13-16 MPa, pre-pressing for 3-4 min when pressing a film, at this time the pressure is 8-12 MPa, then increasing the pressure to 13-16 MPa, and maintaining the pressure for 8-12 min.

[0013] The preparation method of the thermal crosslinking stabilizer in step (1) comprises the following steps:

[0014] S1: preparing a double metal salt solution: adding 4-5 parts by mass of magnesium nitrate and 1-2 parts of zinc nitrate into 90-100 parts of water, dissolving at a speed of 100-300 r / min to obtain a double metal salt solution;

[0015] S2: preparing an alkali solution: adding 0.6-1 parts by mass of sodium hydroxide into 90-100 parts of water, dissolving at a speed of 100-300 r / min to obtain an alkali solution;

[0016] S3, by mass fraction, 40-60 parts of water is heated to 75-85℃ under nitrogen atmosphere, the bimetallic salt solution prepared in step S1 and the base solution prepared in step S2 are added dropwise into the water at a rate of 5-7 mL / min, to obtain a mixed solution; when the dropwise addition is completed, the pH value of the mixed solution is adjusted to 10-11 with the base solution prepared in step S2, and the solution is kept at 75-85℃ for 3-5 h, then it is transferred into an autoclave and reacted at 140-160℃ for 10-14 h, after cooling to room temperature, the product is filtered, washed and dried to obtain Zn-Mg-NO3-LDHs;

[0017] S4, by mass fraction, 1-2 parts of Zn-Mg-NO3-LDHs prepared in step S3 is added into 100-200 mL of exfoliating agent, and stirred at a rate of 60-100 r / min for 24-72 h under nitrogen atmosphere, then the obtained solution is centrifuged at 4000-6000 r / min for 8-10 min, and the supernatant is taken to obtain a Zn-Mg-NO3-LDHs colloidal solution;

[0018] S5, by mass fraction, 0.4-0.6 parts of zinc dicyclopentadiene dicarboxylate is added into 160-180 mL of Zn-Mg-NO3-LDHs colloidal solution prepared in step S4, then the pH value of the solution is adjusted to 7-9 with 0.1 mol / L hydrochloric acid to obtain intermediate A, and finally the intermediate A is placed in an autoclave and reacted at 80-120℃ for 5-10 h, cooled to room temperature, filtered, washed and dried to obtain zinc dicyclopentadiene dicarboxylate modified Zn-Mg-NO3-LDHs.

[0019] The exfoliating agent in step S4 is an ethylammonium nitrate aqueous solution with a concentration of 16-20 wt%.

[0020] The preparation method of the zinc dicyclopentadiene dicarboxylate in step S5 comprises the following steps:

[0021] N1, by mass fraction, 9-11 parts of sodium dicyclopentadiene dicarboxylate is added into 90-110 parts of water, and the insoluble substances and the upper oil layer are filtered out, then the purified sodium dicyclopentadiene dicarboxylate is obtained by extracting with dichloromethane for 3-5 times;

[0022] N2, the purified sodium dicyclopentadiene dicarboxylate prepared in step N1 is added into water to prepare a 0.4-0.6 mol / L sodium dicyclopentadiene dicarboxylate aqueous solution; zinc sulfate is added into water to prepare a 0.9-1.1 mol / L zinc sulfate aqueous solution;

[0023] N3 mixing the aqueous solution of sodium dicyclopentadiene dicarboxylate and the aqueous solution of zinc sulfate prepared in step N2 according to the mass ratio (1-2) :(1-2), stirring at the speed of 100-300 r / min for 10-30 min, filtering, washing and drying to obtain zinc dicyclopentadiene dicarboxylate.

[0024] Because the tertiary chlorine, chlorine-rich group, unsaturated end group and allyl chlorine group on the branch structure unit of the PVC macromolecule are unstable structure units, the chlorine atoms on these unstable structure units are removed in the form of chlorine atoms under the action of heat, and the chlorine atoms are very active, and the carbon from which the chlorine atoms are removed also becomes a free radical, and the energy of the free radical is also high, which inevitably captures a hydrogen atom on the adjacent carbon atom to form a double bond on the macromolecule, and the chlorine atom and the hydrogen atom combine into hydrogen chloride, thereby causing the decomposition of the PVC plastic.

[0025] The weather-resistant and high-temperature-resistant PVC modified plastic prepared in the application has obvious improvement in weather resistance and high-temperature resistance, which is because a new type of thermal crosslinking stabilizer is synthesized in the application, the zinc dicyclopentadiene dicarboxylate is used to modify Zn-Mg-NO3-LDHs, and the modified Zn-Mg-NO3-LDHs are added to the preparation of PVC plastic as a thermal stabilizer, so that the thermal stability of the plastic is further improved. Because the zinc dicyclopentadiene dicarboxylate is insoluble in water and only soluble in ionic liquid, the aqueous solution of ethylammonium nitrate is used as a stripping agent to strip the layers of the layered Zn-Mg-NO3-LDHs, and because ammonium nitrate also has the properties of ionic liquid, the zinc dicyclopentadiene dicarboxylate can be dissolved in the stripping solution prepared in the application in a small amount, so that the zinc dicyclopentadiene dicarboxylate intercalates the Zn-Mg-NO3-LDHs to obtain a thermal stabilizer with excellent dispersibility and high thermal stability. As a layered double metal hydroxide, Zn-Mg-NO3-LDHs itself has a certain thermal stability effect, the layers containing a large amount of hydroxyl groups can effectively absorb the hydrogen chloride generated by the decomposition of PVC, and can also self-decompose, including delaminating interlayer water, removing carbonate ions, and delaminating layer hydroxyl groups, to stabilize the PVC; in addition, the intercalation of the zinc dicyclopentadiene dicarboxylate enhances the dispersibility of the two, so that it has better dispersibility in the PVC plastic, further improving the thermal stability. The zinc ions in the zinc dicyclopentadiene dicarboxylate can neutralize the hydrogen chloride generated by the decomposition of PVC to form zinc chloride, thereby enhancing the thermal stability of the plastic.

[0026] Further, the application adds calcium stearate to the PVC, aiming to neutralize the zinc chloride generated by the reaction of hydrogen chloride and zinc ions, which has certain thermal catalytic properties and can accelerate the decomposition of PVC, so that the calcium stearate is used for neutralization, so as to further convert it into calcium chloride, thereby further enhancing the stability of the prepared weather-resistant and high-temperature-resistant PVC modified plastic.

[0027] The added thermal crosslinking stabilizer also has the effect of improving the mechanical properties of the PVC plastic, the double carboxyl groups in the zinc dicyclopentadiene dicarboxylate can react with the PVC to form ester crosslinking and improve the mechanical properties of the PVC plastic, further, the Zn-Mg-NO3-LDHs can also react with the chlorine atoms on the PVC plastic to form crosslinking, and the zinc dicyclopentadiene dicarboxylate modified Zn-Mg-NO3-LDHs improves its dispersibility in the PVC plastic, which is more conducive to the improvement of its mechanical properties.

[0028] Advantages of the application:

[0029] The application is a new type of thermal crosslinking stabilizer, which uses zinc dicyclopentadiene dicarboxylate modified Zn-Mg-NO3-LDHs, has excellent dispersibility and extremely high thermal stability, and can also improve the mechanical properties of the PVC plastic.

[0030] The application adds the prepared new type of thermal crosslinking stabilizer to the formula of the PVC plastic, greatly improves the thermal stability and mechanical properties of the PVC plastic, and obtains a weather-resistant and high-temperature-resistant PVC modified plastic. DETAILED DESCRIPTION

[0031] Polyvinyl chloride, item number: 032563, Hubei Sheteng Chemical Technology Co., Ltd.

[0032] Superfine active calcium carbonate, item number: 6021, Jiangxi Hengshengtai New Material Co., Ltd.

[0033] Epoxy soybean oil, item number: xx001, Wuhan Xinxinjiali Biological Technology Co., Ltd.

[0034] Zinc dicyclopentadiene dicarboxylate is purchased from Jiaxing Baimiteng New Material Co., Ltd.

[0035] Example 1

[0036] A preparation method of a weather-resistant and high-temperature-resistant PVC modified plastic, comprising the following steps:

[0037] (1) 100 parts of polyvinyl chloride, 15 parts of superfine active calcium carbonate, 6 parts of epoxy soybean oil, and 15 parts of dioctyl phthalate are mixed by stirring at a speed of 60 r / min and heating at a rate of 10 ℃ / min to 120 ℃, stirring is stopped, and the mixture is cooled to 80 ℃ to obtain a preliminary mixture;

[0038] (2) The preliminary mixture obtained in step (1) is added to a double screw extruder, and the double screw extruder is used for melting, mixing, and extruding, and the obtained crude material is cooled to obtain a preliminary mixture;

[0039] (3) The crude material obtained in step (2) is placed in a flat vulcanizing machine, and vulcanization is performed to obtain the weather-resistant and high-temperature-resistant PVC modified plastic.

[0040] The parameters of the double screw extruder in step (2) are as follows: screw rotation speed 60 r / min, conveying section temperature 145 ℃, melting section temperature 180 ℃, homogenizing section temperature 180 ℃, and extrusion melt pressure 28 MPa.

[0041] The parameters of the flat vulcanizing machine in step (3) are as follows: upper and lower plate temperature 180 ℃, pressure 15 MPa, pre-pressing for 3 min when pressing the film, pressure 10 MPa at this time, pre-pressing for 3 min, then increasing the pressure to 15 MPa, and maintaining the pressure for 10 min.

[0042] Example 2

[0043] A method for preparing a weather-resistant and high-temperature-resistant PVC modified plastic, comprising the following steps:

[0044] (1) 100 parts of polyvinyl chloride, 15 parts of superfine active calcium carbonate, 6 parts of epoxy soybean oil, and 15 parts of dioctyl phthalate are mixed by stirring at a speed of 60 r / min and heating at a rate of 10 ℃ / min to 120 ℃, stirring is stopped, and the mixture is cooled to 80 ℃ to obtain a preliminary mixture;

[0045] (2) The preliminary mixture obtained in step (1) is added to a double screw extruder, and the double screw extruder is used for melting, mixing, and extruding, and the obtained crude material is cooled to obtain a preliminary mixture;

[0046] (3) The crude material obtained in step (2) is placed in a flat vulcanizing machine, and vulcanization is performed to obtain the weather-resistant and high-temperature-resistant PVC modified plastic.

[0047] The parameters of the double screw extruder in step (2) are as follows: screw rotation speed 60 r / min, conveying section temperature 145 ℃, melting section temperature 180 ℃, homogenizing section temperature 180 ℃, and extrusion melt pressure 28 MPa.

[0048] The temperature of the upper and lower plates of the flat vulcanizing machine in step (3) is 180℃, and the pressure is 15Mpa. When pressing the film, first pre-press for 3min, at this time the pressure is 10MPa. After pre-pressing for 3min, increase the pressure to 15MPa, and keep the pressure for 10min.

[0049] The preparation method of the thermal crosslinking stabilizer in step (1) comprises the following steps:

[0050] N1Take 10 parts of sodium dicyclopentadiene dicarboxylate by mass fraction, add to 100 parts of water, filter out the insoluble and upper oil layer, then extract 4 times with dichloromethane to obtain purified sodium dicyclopentadiene dicarboxylate;

[0051] N2Prepare a 0.5mol / L sodium dicyclopentadiene dicarboxylate aqueous solution by adding the purified sodium dicyclopentadiene dicarboxylate prepared in step N1 into water; prepare a 1.0mol / L zinc sulfate aqueous solution by adding zinc sulfate into water;

[0052] N3Mix the sodium dicyclopentadiene dicarboxylate aqueous solution and the zinc sulfate aqueous solution prepared in step N2 according to a mass ratio of 2:1, stir at a speed of 200r / min for 20min, filter, wash, and dry to obtain the thermal crosslinking stabilizer.

[0053] Example 3

[0054] A preparation method of a weather-resistant and high-temperature-resistant PVC modified plastic comprises the following steps:

[0055] (1) Mix 100 parts of polyvinyl chloride, 15 parts of ultra-fine active calcium carbonate, 5 parts of thermal crosslinking stabilizer, 6 parts of epoxy soybean oil, and 15 parts of dioctyl phthalate according to mass fraction, stir at a speed of 60r / min, and heat to 120℃ at a rate of 10℃ / min, stop stirring, and cool to 80℃ to obtain a preliminary mixture;

[0056] (2) Put the preliminary mixture prepared in step (1) into a double-screw extruder, melt, mix, and extrude by using the double-screw extruder, and obtain a crude material after cooling;

[0057] (3) Put the crude material prepared in step (2) into a flat vulcanizing machine, vulcanize, and obtain the weather-resistant and high-temperature-resistant PVC modified plastic.

[0058] The parameters of the double-screw extruder in step (2) are as follows: screw rotation speed 60r / min, conveying section temperature 145℃, melting section temperature 180℃, homogenizing section temperature 180℃, and extrusion melt pressure 28MPa.

[0059] The upper and lower plates of the flat vulcanizing machine in step (3) are at 180℃, and the pressure is 15Mpa. When pressing the film, first pre-press for 3min, at this time the pressure is 10MPa. After pre-pressing for 3min, increase the pressure to 15MPa, and keep the pressure for 10min.

[0060] The preparation method of the thermal crosslinking stabilizer in step (1) comprises the following steps:

[0061] S1: preparing a double metal salt solution: 4.4 parts of magnesium nitrate and 1.9 parts of zinc nitrate are added into 100 parts of water, and dissolved at a speed of 200r / min to obtain a double metal salt solution;

[0062] S2: preparing an alkali solution: 0.8 parts of sodium hydroxide is added into 100 parts of water, and dissolved at a speed of 200r / min to obtain an alkali solution;

[0063] S3: under the nitrogen atmosphere, 50 parts of water is heated to 80℃, and the double metal salt solution prepared in step S1 and the alkali solution prepared in step S2 are added dropwise into the water at a speed of 6mL / min to obtain a mixed solution; when the dropping is completed, the pH value of the mixed solution is adjusted to 10 by the alkali solution prepared in step S2, and kept at 80℃ for 4h, and then transferred into an autoclave for reaction at 150℃ for 12h. After being cooled to room temperature, filtration, washing and drying are carried out to obtain Zn-Mg-NO3-LDHs;

[0064] S4: 2 parts of Zn-Mg-NO3-LDHs prepared in step S3 is added into 200mL of a stripping agent, and stirred at a speed of 60r / min for 24h under the nitrogen atmosphere, and then the obtained solution is centrifuged at 6000r / min for 10min, and the supernatant is taken to obtain a Zn-Mg-NO3-LDHs colloidal solution;

[0065] S5: 0.5 parts of zinc dicyclopentadiene dicarboxylate is added into 160mL of the Zn-Mg-NO3-LDHs colloidal solution prepared in step S4, and then the pH value is adjusted to 8 by 0.1mol / L hydrochloric acid to obtain an intermediate A, and finally the intermediate A is placed in an autoclave for reaction at 100℃ for 8h, and cooled to room temperature, and then filtration, washing and drying are carried out to obtain the thermal crosslinking stabilizer.

[0066] The stripping agent in step S4 is an 18wt% ethylammonium nitrate aqueous solution.

[0067] The preparation method of the zinc dicyclopentadiene dicarboxylate in step S5 comprises the following steps:

[0068] N1 10 parts of sodium dicyclopentadiene dicarboxylate are taken in 100 parts of water, and insoluble substances and an upper oil layer are filtered out, and then the purified sodium dicyclopentadiene dicarboxylate is obtained by extracting four times with dichloromethane;

[0069] N2 The purified sodium dicyclopentadiene dicarboxylate prepared in step N1 is added to water to prepare a 0.5 mol / L sodium dicyclopentadiene dicarboxylate aqueous solution; zinc sulfate is added to water to prepare a 1.0 mol / L zinc sulfate aqueous solution;

[0070] N3 The sodium dicyclopentadiene dicarboxylate aqueous solution and the zinc sulfate aqueous solution prepared in step N2 are mixed in a mass ratio of 2:1, stirred at a speed of 200 r / min for 20 min, and the zinc dicyclopentadiene dicarboxylate salt is obtained by filtration, washing and drying.

[0071] Example 4

[0072] A preparation method of a weather-resistant and high-temperature-resistant PVC modified plastic, comprising the following steps:

[0073] (1) 100 parts of polyvinyl chloride, 15 parts of ultra-fine active calcium carbonate, 1.5 parts of calcium stearate, 5 parts of a thermal crosslinking stabilizer, 6 parts of epoxy soybean oil, and 15 parts of dioctyl phthalate are mixed, stirred at a speed of 60 r / min, and heated to 120℃ at a rate of 10℃ / min, and then the stirring is stopped and the temperature is cooled to 80℃ to obtain a preliminary mixture;

[0074] (2) The preliminary mixture prepared in step (1) is added to a double-screw extruder, and the double-screw extruder is used for melting, mixing, and extruding, and the crude material is obtained after cooling;

[0075] (3) The crude material prepared in step (2) is placed in a flat vulcanizing machine, and vulcanized to obtain the weather-resistant and high-temperature-resistant PVC modified plastic.

[0076] The parameters of the double-screw extruder in step (2) are as follows: screw speed 60 r / min, conveying section temperature 145℃, melting section temperature 180℃, homogenizing section temperature 180℃, and extrusion melt pressure 28 MPa.

[0077] The upper and lower plate temperatures of the flat vulcanizing machine in step (3) are 180℃, and the pressure is 15 MPa. When pressing the film, the pressure is first pre-pressed to 10 MPa for 3 min, and then the pressure is increased to 15 MPa after pre-pressing for 3 min, and the pressure is maintained for 10 min.

[0078] The preparation method of the thermal crosslinking stabilizer in step (1) comprises the following steps:

[0079] S1: Preparation of a double metal salt solution: 4.4 parts of magnesium nitrate and 1.9 parts of zinc nitrate were added together into 100 parts of water, and dissolved at a rotation speed of 200 r / min to obtain a double metal salt solution;

[0080] S2: Preparation of an alkali solution: 0.8 parts of sodium hydroxide was added into 100 parts of water, and dissolved at a rotation speed of 200 r / min to obtain an alkali solution;

[0081] S3: 50 parts of water was heated to 80℃ under a nitrogen atmosphere, and the double metal salt solution prepared in step S1 and the alkali solution prepared in step S2 were added dropwise into the water at a rate of 6 mL / min to obtain a mixed solution; when the dropping was completed, the pH value of the mixed solution was adjusted to 10 with the alkali solution prepared in step S2, and the solution was kept at 80℃ for 4 h, and then was transferred into an autoclave for reaction at 150℃ for 12 h; after the solution was cooled to room temperature, filtration, washing and drying were performed to obtain Zn-Mg-NO3-LDHs;

[0082] S4: 2 parts of Zn-Mg-NO3-LDHs prepared in step S3 was added into 200 mL of a peeling agent, and stirred at a rotation speed of 60 r / min for 24 h under a nitrogen atmosphere; then the obtained solution was centrifuged at 6000 r / min for 10 min, and the supernatant was taken to obtain a Zn-Mg-NO3-LDHs colloidal solution;

[0083] S5: 0.5 parts of zinc dicyclopentadiene dicarboxylate was added into 160 mL of the Zn-Mg-NO3-LDHs colloidal solution prepared in step S4, and then the pH value was adjusted to 8 with 0.1 mol / L hydrochloric acid to obtain an intermediate A; finally, the intermediate A was placed in an autoclave for reaction at 100℃ for 8 h, and then was cooled to room temperature, and subjected to filtration, washing and drying to obtain a thermal crosslinking stabilizer.

[0084] The peeling agent in step S4 is an ethylammonium nitrate aqueous solution with a concentration of 18 wt%.

[0085] The preparation method of the zinc dicyclopentadiene dicarboxylate in step S5 comprises the following steps:

[0086] N1: 10 parts of sodium dicyclopentadiene dicarboxylate was added into 100 parts of water, and the insoluble substances and the upper oil layer were filtered out, and then the purified sodium dicyclopentadiene dicarboxylate was obtained by extraction with dichloromethane for 4 times;

[0087] N2: The purified sodium dicyclopentadiene dicarboxylate prepared in step N1 was added into water to prepare a 0.5 mol / L sodium dicyclopentadiene dicarboxylate aqueous solution; and zinc sulfate was added into water to prepare a 1.0 mol / L zinc sulfate aqueous solution;

[0088] N3 mixing the aqueous solution of sodium dicyclopentadiene dimethylate and the aqueous solution of zinc sulfate prepared in step N2 according to a mass ratio of 2:1, stirring at a rotating speed of 200 r / min for 20 min, filtering, washing and drying to obtain the zinc dicyclopentadiene dimethylate.

[0089] Example 5

[0090] A preparation method of a weather-resistant and high-temperature-resistant PVC modified plastic, comprising the following steps:

[0091] (1) according to mass fraction, 100 parts of polyvinyl chloride, 15 parts of superfine active calcium carbonate, 1.5 parts of calcium stearate, 6 parts of epoxy soybean oil, 15 parts of dioctyl phthalate are mixed, stirred at a rotating speed of 60 r / min, and heated to 120℃ at a rate of 10℃ / min, the stirring is stopped, and cooled to 80℃ to obtain a preliminary mixture;

[0092] (2) the preliminary mixture prepared in step (1) is added into a double screw extruder, and the double screw extruder is used for melting, mixing and extruding, and the crude material is obtained after cooling;

[0093] (3) the crude material prepared in step (2) is placed into a flat vulcanizing machine, and vulcanized to obtain the weather-resistant and high-temperature-resistant PVC modified plastic.

[0094] The parameters of the double screw extruder in step (2) are as follows: screw rotating speed of 60 r / min, conveying section temperature of 145℃, melting section temperature of 180℃, homogenizing section temperature of 180℃, and extrusion melt pressure of 28 MPa.

[0095] The upper and lower plate temperatures of the flat vulcanizing machine in step (3) are 180℃, the pressure is 15 MPa, and when pressing the film, the pressure is first pre-pressed for 3 min, at this time the pressure is 10 MPa, after pre-pressing for 3 min, the pressure is increased to 15 MPa, and the pressure is maintained for 10 min.

[0096] Example 6

[0097] A preparation method of a weather-resistant and high-temperature-resistant PVC modified plastic, comprising the following steps:

[0098] (1) according to mass fraction, 100 parts of polyvinyl chloride, 15 parts of superfine active calcium carbonate, 1.5 parts of calcium stearate, 5 parts of thermal crosslinking stabilizer, 6 parts of epoxy soybean oil, 15 parts of dioctyl phthalate are mixed, stirred at a rotating speed of 60 r / min, and heated to 120℃ at a rate of 10℃ / min, the stirring is stopped, and cooled to 80℃ to obtain a preliminary mixture;

[0099] (2) the preliminary mixture prepared in step (1) is added into a double screw extruder, and the double screw extruder is used for melting, mixing and extruding, and the crude material is obtained after cooling;

[0100] (3) placing the crude material prepared in step (2) into a flat vulcanizing machine to vulcanize, so as to obtain the weather-resistant and high-temperature-resistant PVC modified plastic.

[0101] The parameters of the double-screw extruder in step (2) are as follows: screw rotation speed 60 r / min, conveying section temperature 145 ℃, melting section temperature 180 ℃, homogenizing section temperature 180 ℃, and extrusion melt pressure 28 MPa.

[0102] The parameters of the flat vulcanizing machine in step (3) are as follows: upper and lower plate temperature 180 ℃, pressure 15 MPa, and pre-pressing for 3 min when pressing the film, at this time the pressure is 10 MPa, and after pre-pressing for 3 min, the pressure is increased to 15 MPa and the pressure is maintained for 10 min.

[0103] The preparation method of the thermal crosslinking stabilizer in step (1) comprises the following steps:

[0104] S1: preparing a double-metal salt solution: 4.4 parts of magnesium nitrate and 1.9 parts of zinc nitrate are added into 100 parts of water, and dissolved at a rotation speed of 200 r / min to obtain a double-metal salt solution;

[0105] S2: preparing an alkali solution: 0.8 parts of sodium hydroxide is added into 100 parts of water, and dissolved at a rotation speed of 200 r / min to obtain an alkali solution;

[0106] S3: under a nitrogen atmosphere, 50 parts of water is heated to 80 ℃, and the double-metal salt solution prepared in step S1 and the alkali solution prepared in step S2 are added dropwise into the water at a rate of 6 mL / min to obtain a mixed solution; when the dropwise addition is completed, the pH value of the mixed solution is adjusted to 10 by using the alkali solution prepared in step S2, and the solution is kept at 80 ℃ for 4 h, and then is transferred into an autoclave for reaction at 150 ℃ for 12 h; after the solution is cooled to room temperature, filtration, washing and drying are performed to obtain the thermal crosslinking stabilizer.

[0107] Test Example 1

[0108] 7 mg of the weather-resistant and high-temperature-resistant PVC modified plastic prepared in each embodiment is taken for thermogravimetric test, specifically, nitrogen gas with a flow rate of 30 mL / min is used for purging, and the temperature is increased from 30 ℃ at a speed of 20 ℃ / min, and the initial temperature of weight loss of each sample is recorded. The results are shown in Table 1.

[0109] Table 1: Analysis results of thermogravimetric test

[0110]

[0111]

[0112] As can be seen from Table 1, the weather-resistant and high-temperature-resistant PVC modified plastic prepared in Example 1 has the lowest initial temperature of weight loss, because the tertiary chlorine, chlorine-rich groups, unsaturated end groups and allyl chloride groups on the branched structure units of the PVC macromolecule are unstable structure units. The chlorine atoms on these unstable structure units are removed in the form of chlorine atoms under the action of heat, and the carbon atoms from which the chlorine atoms are removed also become free radicals, which inevitably capture a hydrogen atom on the adjacent carbon atom to form a double bond on the macromolecule, and the chlorine atom and the hydrogen atom combine to form hydrogen chloride, thereby causing the decomposition of the PVC plastic.

[0113] The weather-resistant and high-temperature-resistant PVC modified plastic prepared in Example 2 has a significantly higher initial temperature of weight loss than that of Example 1, which indicates that it has a higher temperature of initial decomposition and has more excellent high-temperature resistance. This is because the thermal crosslinking stabilizer (zinc dicyclopentadiene dicarboxylate) is added in Example 2, and the zinc ions in the thermal crosslinking stabilizer can neutralize the hydrogen chloride generated by the decomposition of PVC to form zinc chloride, thereby enhancing the thermal stability of the plastic.

[0114] In Example 3, Zn-Mg-NO3-LDHs is further modified by zinc dicyclopentadiene dicarboxylate, and the modified Zn-Mg-NO3-LDHs is added as a thermal stabilizer to the preparation of PVC plastic, so that the thermal stability of the plastic is further improved. The present application believes that this is because the present application uses an aqueous ethylammonium nitrate solution as a stripping agent to strip the layers of the layered Zn-Mg-NO3-LDHs. Since ammonium nitrate also has the properties of an ionic liquid, a small amount of zinc dicyclopentadiene dicarboxylate can be dissolved in the stripping solution prepared in the present application, so that zinc dicyclopentadiene dicarboxylate is intercalated into Zn-Mg-NO3-LDHs, obtaining a thermal stabilizer with excellent dispersibility and extremely high thermal stability. As a layered double metal hydroxide, Zn-Mg-NO3-LDHs itself has a certain thermal stability effect, and its layer containing a large amount of hydroxyl groups can effectively absorb the hydrogen chloride generated by the decomposition of PVC, and with the increase of temperature, it can also be self-decomposed, including the removal of interlayer water, the removal of carbonate ions, the dehydration of layer hydroxyl groups, etc. to stabilize PVC; in addition, the intercalation of zinc dicyclopentadiene dicarboxylate enhances the dispersibility of both, so that it has better dispersibility in PVC plastic, further improving its thermal stability.

[0115] Further in Example 4, calcium stearate is added to the PVC, which is used to neutralize the zinc chloride produced by the reaction of hydrogen chloride and zinc ions, and the zinc chloride has certain thermal catalytic properties, which can accelerate the decomposition of PVC, so that the stability of the prepared weather-resistant and high-temperature-resistant PVC modified plastic is further improved. In Example 5, only calcium stearate is added, and the thermal stability is obviously decreased, which shows that the addition of calcium stearate alone has no obvious thermal stabilizing effect.

[0116] In Example 6, only Zn-Mg-NO3-LDHs is added without modification by zinc dicyclopentadiene dicarboxylate, and the thermal stability of the prepared weather-resistant and high-temperature-resistant PVC modified plastic is obviously decreased, which shows that the thermal stabilizing effect of pure Zn-Mg-NO3-LDHs is poor, and calcium stearate has no promoting effect on it.

[0117] Test Example 2

[0118] The mechanical properties of the weather-resistant and high-temperature-resistant PVC modified plastic prepared in each example of the present application were tested according to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: test conditions for films and sheets".

[0119] Sample size: 20 mm wide, 150 mm long, 0.8 mm thick.

[0120] Test conditions: temperature 25℃, relative humidity 50%, tensile rate 5mm / min, inlet force: 0.5N.

[0121] Test instrument: universal mechanical testing machine.

[0122] Table 2: tensile strength test results

[0123] Tensile strength (MPa) Example 1 47 Example 2 54 Example 3 57

[0124] As can be seen from Table 2, the thermal crosslinking stabilizer added in the present application also has the effect of improving the mechanical properties of PVC plastic. The double carboxyl groups in zinc dicyclopentadiene dicarboxylate can react with PVC to form ester crosslinking, thereby improving the mechanical properties of PVC plastic. Further, Zn-Mg-NO3-LDHs can also react with chlorine atoms on the PVC plastic to form crosslinking, and the modification of Zn-Mg-NO3-LDHs by zinc dicyclopentadiene dicarboxylate improves its dispersibility in PVC plastic, which is more conducive to the improvement of its mechanical properties.

Claims

1. A method for preparing weather-resistant and high-temperature-resistant PVC modified plastic, characterized in that, The method comprises the following steps: (1) mixing and stirring polyvinyl chloride, ultrafine active calcium carbonate, calcium stearate, thermal crosslinking stabilizer, epoxy soybean oil and dioctyl phthalate according to mass fraction, and heating to 100-130 DEG C, stopping stirring, and cooling to obtain a preliminary mixture; (2) adding the preliminary mixture prepared in step (1) into a double screw extruder, melting, mixing and extruding by the double screw extruder, and cooling to obtain a crude material; (3) placing the crude material prepared in step (2) into a flat vulcanizing machine, vulcanizing to obtain the weather-resistant and high-temperature-resistant PVC modified plastic. The preparation method of the thermal crosslinking stabilizer comprises the following steps: S1, preparing a double metal salt solution: adding 4-5 parts of magnesium nitrate and 1-2 parts of zinc nitrate into 90-100 parts of water, dissolving at a speed of 100-300 r / min to obtain a double metal salt solution; S2, preparing an alkali solution: adding 0.6-1 parts of sodium hydroxide into 90-100 parts of water, dissolving at a speed of 100-300 r / min to obtain an alkali solution; S3, under a nitrogen atmosphere, heating 40-60 parts of water to 75-85 DEG C, adding the double metal salt solution prepared in step S1 and the alkali solution prepared in step S2 into the water at a speed of 5-7 mL / min to obtain a mixed solution; when the adding is completed, adjusting the pH value of the mixed solution to 10-11 by using the alkali solution prepared in step S2, keeping the temperature at 75-85 DEG C for 3-5 h, then transferring the solution into an autoclave, reacting at 140-160 DEG C for 10-14 h, cooling to room temperature, and then filtering, washing and drying to obtain Zn-Mg-NO3-LDHs; S4, placing 1-2 parts of Zn-Mg-NO3-LDHs prepared in step S3 into 100-200 mL of a peeling agent, stirring at a speed of 60-100 r / min for 24-72 h under a nitrogen atmosphere, then centrifuging the obtained solution at 4000-6000 r / min for 8-10 min, taking the supernatant to obtain a Zn-Mg-NO3-LDHs colloidal solution; S5, adding 0.4-0.6 parts of a zinc dicyclopentadiene dicarboxylate salt into 160-180 mL of the Zn-Mg-NO3-LDHs colloidal solution prepared in step S4, then adjusting the pH value of the solution to 7-9 by using hydrochloric acid to obtain an intermediate A, and finally placing the intermediate A into an autoclave, reacting at 80-120 DEG C for 5-10 h, cooling to room temperature, and then filtering, washing and drying to obtain the thermal crosslinking stabilizer.

2. The process for preparing weather resistant and high temperature resistant PVC modified plastics as claimed in claim 1 wherein, In step (2), the parameters of the double screw extruder are as follows: the screw rotation speed is 40-60 r / min, the temperature of the conveying section is 140-145 DEG C, the temperature of the melting section is 175-180 DEG C, the temperature of the homogenizing section is 175-180 DEG C, and the extrusion melt pressure is 26-30 MPa.

3. The method of claim 1, wherein the weather-resistant and high-temperature-resistant PVC modified plastic is prepared by adding 0.1-0.5 parts by weight of the weather-resistant and high-temperature-resistant PVC modified plastic to 100 parts by weight of PVC, and then mixing and kneading the mixture. The temperature of the upper and lower plates of the flat vulcanizing machine in step (3) is 170-185℃, the pressure is 13-16Mpa, and the film is pre-pressed for 3-4min when the pressure is 8-12MPa, then the pressure is increased to 13-16MPa and maintained for 8-12min.

4. The method of claim 1, wherein the weather-resistant and high-temperature-resistant PVC modified plastic is prepared by adding 0.1-0.5 parts by weight of the weather-resistant and high-temperature-resistant PVC modified plastic to 100 parts by weight of PVC, and then mixing and kneading the mixture. The stripping agent in step S4 is an ethyl ammonium nitrate aqueous solution with a concentration of 16-20wt%.

5. The method for preparing the weather-resistant and high-temperature-resistant modified PVC plastic as described in claim 1, characterized in that, The concentration of the hydrochloric acid in step S5 is 0.1-0.2mol / L.

6. The method for preparing the weather-resistant and high-temperature-resistant modified PVC plastic as described in claim 1, characterized in that, The preparation method of the zinc dicyclopentadiene dimethylate salt in step S5 comprises the following steps: N1 9-11 parts of sodium dicyclopentadiene dimethylate is taken in 90-110 parts of water, the insoluble substances and the upper oil layer are filtered out, then the purified sodium dicyclopentadiene dimethylate is obtained by extracting 3-5 times with dichloromethane; N2 the purified sodium dicyclopentadiene dimethylate prepared in step N1 is added in water to prepare a 0.4-0.6mol / L sodium dicyclopentadiene dimethylate aqueous solution; zinc sulfate is added in water to prepare a 0.9-1.1mol / L zinc sulfate aqueous solution; N3 the sodium dicyclopentadiene dimethylate aqueous solution and the zinc sulfate aqueous solution prepared in step N2 are mixed in a mass ratio of (1-2):(1-2), stirred at a speed of 100-300r / min for 10-30min, filtered, washed and dried to obtain the zinc dicyclopentadiene dimethylate salt.

7. A weather-resistant and high-temperature-resistant PVC modified plastic, characterized in that, The weather-resistant and high-temperature-resistant PVC modified plastic is prepared by the preparation method of the weather-resistant and high-temperature-resistant PVC modified plastic according to any one of claims 1-6.

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