A calcium-based powder material for PVC hard products and a preparation method thereof

Abstract

The present invention discloses a calcium-based powder material for PVC hard products and a preparation method thereof, and belongs to the technical field of powder materials. The calcium-based powder material for PVC hard products comprises the following steps: S1, stirring the calcium-based material, dimethylethanolamine and water to obtain a suspension, adding amino polysiloxane to the suspension and heating and stirring to obtain silane-modified calcium carbonate; S2, uniformly mixing the above-mentioned silane-modified calcium carbonate, water, and N,N-dimethylformamide, then adding graphene oxide ultrasound, then heating and stirring, cooling and filtering, washing, drying, grinding, and obtaining the calcium-based powder material for PVC hard products. The present invention is applied to the technical field of PVC hard products by improving the agglomeration and compatibility problems of calcium carbonate powder, thereby improving the mechanical properties of the calcium-based powder material for PVC hard products and expanding its scope of application.

Description

Technical Field

[0001] The invention relates to the technical field of powder materials, and in particular to a calcium-based powder material for PVC hard products and a preparation method thereof. Background Art

[0002] At present, the commonly used fillers for polyvinyl chloride (PVC) materials are still calcium carbonate, fly ash, etc., which play a role as a skeleton in PVC products, can improve the dimensional stability, hardness, rigidity, heat resistance of plastic products, and can reduce the cost of products; however, the improvement of the tensile strength and impact strength of PVC products is insufficient, and special impact modifiers must be added to improve the performance. If calcium carbonate with different functions can be applied to PVC hard composite materials, it will replace the more expensive impact modifier and reduce the production cost of products.

[0003] Calcium carbonate is a fibrous green environmentally friendly material that grows in single crystals with almost no defects inside the crystals. This perfect characteristic gives it excellent properties such as high strength, heat resistance and good heat insulation. And due to its low price, non-toxicity, tastelessness, and high whiteness, it is widely used as a filler in the production process of rubber and plastics. Calcium carbonate is the most commonly used filler material in the processing of PVC products. It can improve the mechanical properties, thermal properties, toughness and surface processing properties of PVC products. At the same time, the low price of calcium carbonate can reduce costs. However, because the carbonate ions on the surface of calcium carbonate are easily hydrolyzed, a large number of hydroxyl groups exist on its surface, so it is hydrophilic and difficult to mix with base materials such as polar organic polymers with poor affinity. The agglomeration phenomenon is serious, which seriously limits its application field as a filler. Surface modification of calcium carbonate can better solve this problem.

[0004] A Chinese invention patent (application number: 202111625950.X) discloses a functionalized nano-calcium carbonate for rigid PVC, which comprises the following steps: adding a modified solution composed of sodium stearate, epoxy linseed oil and sorbitan monostearate to the suspension after the carbonation reaction for a primary surface modification; then adding a modified solution composed of barium salt and zinc salt to the suspension for a secondary surface modification to obtain a modified calcium carbonate suspension; finally, the modified calcium carbonate suspension is filtered, dried and sieved to obtain the functionalized nano-calcium carbonate filled with rigid PVC. The functionalized nano-calcium carbonate prepared by this invention can only give rigid PVC products better mechanical properties, but the mechanical properties in this invention are not very good, with the best tensile properties being only 47.02MPa and the impact resistance being 46.95kJ·m -2 , it cannot be used at all in many high-intensity high-altitude operations, which greatly limits its scope of application. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention provides a calcium-based powder material for PVC hard products and a preparation method thereof.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0007] A method for preparing a calcium-based powder material for PVC hard products comprises the following steps:

[0008] The calcium-based material, dimethylethanolamine and water are stirred to obtain a suspension, and amino polysiloxane is added to the suspension, heated and stirred, centrifuged, dried and ground to obtain a calcium-based powder material for PVC hard products.

[0009] Preferably, the method for preparing the calcium-based powder material for PVC hard products comprises the following steps: stirring 18-25 parts by weight of calcium-based material, 0.2-0.5 parts by weight of dimethylethanolamine and 120-200 parts by weight of water to obtain a suspension, adding 3-6 parts by weight of amino polysiloxane to the suspension, stirring at 55-75°C and 400-800rpm for 0.5-3h, centrifuging, washing, drying and grinding to obtain the calcium-based powder material for PVC hard products.

[0010] Since calcium carbonate is a hydrophilic inorganic compound, it has poor compatibility with PVC polymers, is easy to agglomerate, and causes uneven internal dispersion, thereby reducing product performance, so it is necessary to improve the dispersibility of calcium carbonate. In order to enhance the comprehensive utilization ability of calcium-based materials for PVC composite products, research is conducted on the mechanical properties and processing properties of PVC products and the agglomeration and compatibility problems of calcium carbonate powder. Adding calcium carbonate has a certain effect on improving certain properties of plastic products to expand their application range. In plastic processing, they can reduce resin shrinkage, improve rheology, and control viscosity. However, calcium carbonate has a hydrophilic surface and poor compatibility with plastic matrix. Directly filling calcium carbonate into PVC pipes as an impact modifier has poor dispersibility and is easy to agglomerate. Therefore, it is necessary to improve its surface properties by subjecting it to surface hydrophobic treatment.

[0011] In order to better reduce the surface polarity of calcium carbonate, optimize the oil absorption index, improve the hydrophobicity, and improve the dispersibility and compatibility of calcium carbonate powder in high molecular organic matter.

[0012] Aminated polysiloxane can be used to modify calcium carbonate to improve its compatibility and dispersibility in PVC. This modification method involves typing hydrophobic organic groups on the surface of inorganic particles, thereby reducing the surface energy and enhancing the compatibility and dispersibility of inorganic particles in organic systems. The surface properties of calcium carbonate can be effectively changed by modifiers such as silane coupling agents. The coupling agent reacts chemically with the hydroxyl groups on the surface of calcium carbonate to introduce hydrophobic organic groups, thereby reducing its surface energy and making it easier to disperse in the PVC matrix. The modified calcium carbonate can not only improve the processing properties of PVC, but also enhance its mechanical properties, aging resistance, etc., thereby improving the quality and performance of the overall product.

[0013] In summary, the key to amino polysiloxane-modified calcium carbonate is to improve its surface properties, making it more adaptable to the PVC matrix, thereby improving compatibility and dispersibility, and thus improving the performance of the final product.

[0014] The graphene-grafted cross-linked polymer contains hydrophilic hydroxyl groups and has good dispersibility in ethanol-water solution. The graphene-grafted cross-linked polymer contains 4-hydroxybutyl acrylate structural units, and its polymer molecular chain has excellent compatibility with polyvinyl chloride, so that graphene can be better dispersed in the polyvinyl chloride matrix, which has an excellent reinforcement effect and improves the tensile properties and Shore hardness of polyvinyl chloride. The introduction of functionalized graphene can improve the stiffness and strength of the material. In addition, the two-dimensional structure of functionalized graphene helps to disperse stress, thereby further improving the mechanical properties of the material.

[0015] Furthermore, the method for preparing the calcium-based powder material for PVC hard products comprises the following steps: S1, stirring the calcium-based material, dimethylethanolamine and water to obtain a suspension, adding amino polysiloxane to the suspension, heating and stirring, to obtain silane-modified calcium carbonate;

[0016] S2. Evenly mix the above-mentioned silane-modified calcium carbonate, water and N,N-dimethylformamide, add graphene oxide and perform ultrasound, heat and stir, cool and filter, wash, dry and grind to obtain a calcium-based powder material for PVC hard products.

[0017] Preferably, the method for preparing the calcium-based powder material for PVC hard products comprises the following steps: S1, mixing 18-25 parts by weight of calcium-based material, 0.2-0.5 parts by weight of dimethylethanolamine and 120-200 parts by weight of

[0018] parts by weight of water to obtain a suspension, add 3-6 parts by weight of amino polysiloxane to the suspension, stir at 55-75° C. and 400-800 rpm for 0.5-3 h, centrifuge, wash, dry, and grind to obtain silane-modified calcium carbonate;

[0019] S2. Evenly mix 10-20 parts by weight of the above-mentioned silane-modified calcium carbonate, 20-40 parts by weight of water, and 80-160 parts by weight of N,N-dimethylformamide, and then add 2-5 parts by weight of graphene oxide, ultrasonically treat at an ultrasonic power of 100-300 W and an ultrasonic frequency of 40-70 kHz for 20-50 min, and then stir at 85-100 ° C and 400-800 rpm for 30-70 min, cool and filter, wash, dry, and grind to obtain a calcium-based powder material for PVC hard products.

[0020] Combining modified calcium carbonate and functionalized graphene can achieve a synergistic effect, and the mechanism is as follows: the combination of amino polysiloxane-modified calcium carbonate and functionalized graphene may improve the overall mechanical properties by enhancing the interfacial interaction between the filler and the PVC matrix; the combined use of the two fillers helps to achieve a more uniform filler dispersion in the PVC matrix and reduce agglomeration, thereby improving the performance of the material. Aminated polysiloxane-modified calcium carbonate provides good dispersibility and compatibility, while carboxylated graphene provides excellent mechanical reinforcement. The combination of the two achieves a reinforcement effect at multiple levels.

[0021] In summary, the combination of amino polysiloxane-modified calcium carbonate and functionalized graphene significantly improves the mechanical properties of PVC hard products by improving the dispersibility of fillers in PVC, enhancing interfacial interactions and multiple strengthening effects.

[0022] Furthermore, the preparation method of the calcium-based powder material for PVC hard products comprises the following steps: S1, stirring the calcium-based material, dimethylethanolamine and water to obtain a suspension, adding amino polysiloxane to the suspension, heating and stirring, to obtain silane-modified calcium carbonate;

[0023] S2, mixing graphene oxide and N,N-dimethylformamide and refluxing, filtering, washing, adding xylene for ultrasonication, then adding 4-hydroxybutyl acrylate and triethylamine for heating and stirring, filtering, washing, and drying to obtain functionalized graphene;

[0024] S3. Evenly mix the above-mentioned silane-modified calcium carbonate, water and N,N-dimethylformamide, add functionalized graphene and perform ultrasound, heat and stir, cool and filter, wash, dry and grind to obtain calcium-based powder material for PVC hard products.

[0025] Preferably, the method for preparing the calcium-based powder material for PVC hard products comprises the following steps:

[0026] S1, 18-25 parts by weight of calcium-based material, 0.2-0.5 parts by weight of dimethylethanolamine and 120-200 parts by weight of water are stirred to obtain a suspension, 3-6 parts by weight of amino polysiloxane are added to the suspension, stirred at 55-75° C. and 400-800 rpm for 0.5-3 h, centrifuged, washed, and dried to obtain silane-modified calcium carbonate;

[0027] S2. Under nitrogen protection, 5-12 parts by weight of graphene oxide and 100-300 parts by weight of N,N-dimethylformamide are mixed, refluxed at 68-80° C. for 5-10 h, filtered, washed, 100-200 parts by weight of xylene are added, ultrasonicated at an ultrasonic power of 200-600 W and an ultrasonic frequency of 40-80 kHz for 30-60 min, 5-12 parts by weight of 4-hydroxybutyl acrylate and 0.5-2 parts by weight of triethylamine are added, stirred at 25-35° C. and 200-600 rpm for 12-30 h, filtered, washed, and dried to obtain functionalized graphene;

[0028] S3. Evenly mix 10-20 parts by weight of the modified calcium carbonate, 20-40 parts by weight of water, and 80-160 parts by weight of N,N-dimethylformamide, and then add 2-5 parts by weight of functionalized graphene, ultrasonically treat for 20-50 minutes at an ultrasonic power of 100-300 W and an ultrasonic frequency of 40-70 kHz, and then stir at 85-100° C. and 400-800 rpm for 30-70 minutes, cool and filter, wash, dry, and grind to obtain a calcium-based powder material for PVC hard products.

[0029] The calcium-based material is calcium carbonate.

[0030] The preparation method of the amino polysiloxane is as follows: γ-diethylenetriaminepropylmethyldimethoxysilane, octamethylcyclotetrasiloxane, methyloctadecyldiethoxysilane, potassium hydroxide and water are heated for pre-reaction, and then (3-aminopropyl)dimethylmethoxysilane is added and the reaction is continued to obtain the amino polysiloxane.

[0031] Preferably, the preparation method of the amino polysiloxane is as follows: under nitrogen protection, 8-12 parts by weight of γ-diethylenetriaminepropylmethyldimethoxysilane, 80-100 parts by weight of octamethylcyclotetrasiloxane, 7-12 parts by weight of methyloctadecyldiethoxysilane, 0.5-1 parts by weight of potassium hydroxide, and 2-8 parts by weight of water are mixed, pre-reacted at 85-110° C. for 2-5 hours, and then 1-3 parts by weight of (3-aminopropyl)dimethylmethoxysilane is added, the reaction is continued for 20-50 hours, and reduced pressure distillation is performed to obtain the amino polysiloxane.

[0032] The calcium-based powder material for PVC hard products is prepared by any of the above methods.

[0033] Beneficial effects of the present invention: The present invention provides a calcium-based powder material for PVC hard products and a preparation method thereof. In order to enhance the comprehensive utilization of calcium-based materials for PVC composite products, the present invention aims at the mechanical properties of PVC products and the agglomeration and compatibility problems of calcium carbonate powder, establishes a ternary composite system of PVC, calcium carbonate and dispersant, studies the interaction between the three, and improves the dispersibility of calcium carbonate in resin and applies it to PVC hard products, ultimately achieving the improvement of the mechanical properties of calcium-based powder materials for PVC hard products, thereby broadening its application range. DETAILED DESCRIPTION

[0034] The above content of the present invention is further described in detail below in conjunction with specific implementation modes, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments.

[0035] The raw materials in the examples, comparative examples and test examples of the present application are all commercially available products, and the introduction of some of the raw materials is as follows:

[0036] PVC resin was purchased from Jinan Xiangfeng Weiye Chemical Co., Ltd., brand: SG-5.

[0037] Polyethylene glycol was purchased from Haian Petrochemical Plant in Jiangsu Province, model: PEG-4000.

[0038] The calcium-zinc composite stabilizer was a commercially available product purchased from Changzhou Rongren Trading Co., Ltd., model: XQGX-212.

[0039] Maleic anhydride grafted styrene was purchased from Dongguan Jingke Polymer Co., Ltd., brand: ST-01.

[0040] Activated calcium carbonate was purchased from Lingshou County Malin Mineral Products Processing Plant, mesh number: 1250 mesh.

[0041] Graphene oxide was purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd., catalog number: EF234243.

[0042] Example 1

[0043] A method for preparing a calcium-based powder material for PVC hard products comprises the following steps:

[0044] S1, 20 parts by weight of activated calcium carbonate, 0.3 parts by weight of dimethylethanolamine and 150 parts by weight of water were stirred to obtain a suspension, 4.5 parts by weight of amino polysiloxane were added to the suspension, stirred at 60° C. and 600 rpm for 1 h, centrifuged, washed, and dried to obtain silane-modified calcium carbonate;

[0045] S2. Under nitrogen protection, 10 parts by weight of graphene oxide and 200 parts by weight of N,N-dimethylformamide were mixed, refluxed at 70°C for 8 hours, filtered, washed, 150 parts by weight of xylene were added, ultrasonicated at an ultrasonic power of 400W and an ultrasonic frequency of 60kHz for 40 minutes, 8 parts by weight of 4-hydroxybutyl acrylate and 1 part by weight of triethylamine were added, stirred at 30°C and 400rpm for 18 hours, filtered, washed, and dried to obtain functionalized graphene;

[0046] S3. Evenly mix 15 parts by weight of the modified calcium carbonate, 30 parts by weight of water, and 100 parts by weight of N,N-dimethylformamide, and then add 3 parts by weight of functionalized graphene. Ultrasonicate at an ultrasonic power of 200 W and an ultrasonic frequency of 60 kHz for 30 minutes, and then stir at 90°C and 600 rpm for 40 minutes. Cool and filter, wash, dry, and grind to obtain a calcium-based powder material for PVC hard products.

[0047] The preparation method of the amino polysiloxane is as follows: under nitrogen protection, 10 parts by weight of γ-diethylenetriaminepropylmethyldimethoxysilane, 90 parts by weight of octamethylcyclotetrasiloxane, 10 parts by weight of methyloctadecyldiethoxysilane, 0.8 parts by weight of potassium hydroxide, and 3 parts by weight of water are mixed, pre-reacted at 90° C. for 3 hours, and then 2 parts by weight of (3-aminopropyl)dimethylmethoxysilane are added, and the reaction is continued for 40 hours, and reduced pressure distillation is performed to obtain the amino polysiloxane.

[0048] Example 2

[0049] A method for preparing a calcium-based powder material for PVC hard products comprises the following steps:

[0050] S1, 18 parts by weight of activated calcium carbonate, 0.5 parts by weight of dimethylethanolamine and 120 parts by weight of water were stirred to obtain a suspension, 6 parts by weight of amino polysiloxane were added to the suspension, stirred at 55° C. and 800 rpm for 0.5 h, centrifuged, washed, and dried to obtain silane-modified calcium carbonate;

[0051] S2. Under nitrogen protection, 12 parts by weight of graphene oxide and 100 parts by weight of N,N-dimethylformamide were mixed, refluxed at 80° C. for 5 h, filtered, washed, 100 parts by weight of xylene were added, ultrasonicated at an ultrasonic power of 600 W and an ultrasonic frequency of 40 kHz for 60 min, 5 parts by weight of 4-hydroxybutyl acrylate and 2 parts by weight of triethylamine were added, stirred at 25° C. and 600 rpm for 12 h, filtered, washed, and dried to obtain functionalized graphene;

[0052] S3. Evenly mix 20 parts by weight of the modified calcium carbonate, 20 parts by weight of water and 160 parts by weight of N,N-dimethylformamide, add 2 parts by weight of functionalized graphene, ultrasonicate for 50 minutes at an ultrasonic power of 300 W and an ultrasonic frequency of 40 kHz, stir for 30 minutes at 85°C and 800 rpm, cool and filter, wash, dry and grind to obtain a calcium-based powder material for PVC hard products.

[0053] The preparation method of the amino polysiloxane is as follows: under nitrogen protection, 8 parts by weight of γ-diethylenetriaminepropylmethyldimethoxysilane, 100 parts by weight of octamethylcyclotetrasiloxane, 7 parts by weight of methyloctadecyldiethoxysilane, 1 part by weight of potassium hydroxide, and 2 parts by weight of water are mixed, pre-reacted at 110° C. for 2 hours, and then 3 parts by weight of (3-aminopropyl)dimethylmethoxysilane is added, the reaction is continued for 20 hours, and reduced pressure distillation is performed to obtain the amino polysiloxane.

[0054] Example 3

[0055] A method for preparing a calcium-based powder material for PVC hard products comprises the following steps:

[0056] S1, 25 parts by weight of activated calcium carbonate, 0.2 parts by weight of dimethylethanolamine and 200 parts by weight of water were stirred to obtain a suspension, 3 parts by weight of amino polysiloxane were added to the suspension, stirred at 75° C. and 400 rpm for 3 h, centrifuged, washed, and dried to obtain silane-modified calcium carbonate;

[0057] S2. Under nitrogen protection, 5 parts by weight of graphene oxide and 300 parts by weight of N,N-dimethylformamide were mixed, refluxed at 68° C. for 10 h, filtered, washed, 200 parts by weight of xylene were added, ultrasonicated at an ultrasonic power of 200 W and an ultrasonic frequency of 80 kHz for 30 min, 12 parts by weight of 4-hydroxybutyl acrylate and 0.5 parts by weight of triethylamine were added, stirred at 35° C. and 200 rpm for 30 h, filtered, washed, and dried to obtain functionalized graphene;

[0058] S3. Evenly mix 10 parts by weight of the modified calcium carbonate, 40 parts by weight of water and 80 parts by weight of N,N-dimethylformamide, add 5 parts by weight of functionalized graphene, ultrasonicate for 20 minutes at an ultrasonic power of 100 W and an ultrasonic frequency of 70 kHz, stir for 70 minutes at 100°C and 400 rpm, cool and filter, wash, dry and grind to obtain a calcium-based powder material for PVC hard products.

[0059] The preparation method of the amino polysiloxane is as follows: under nitrogen protection, 12 parts by weight of γ-diethylenetriaminepropylmethyldimethoxysilane, 80 parts by weight of octamethylcyclotetrasiloxane, 12 parts by weight of methyloctadecyldiethoxysilane, 0.5 parts by weight of potassium hydroxide, and 8 parts by weight of water are mixed, pre-reacted at 85° C. for 5 hours, and then 1 part by weight of (3-aminopropyl)dimethylmethoxysilane is added, and the reaction is continued for 50 hours, and reduced pressure distillation is performed to obtain the amino polysiloxane.

[0060] Comparative Example 1

[0061] A method for preparing a calcium-based powder material for PVC hard products comprises the following steps:

[0062] S1, 20 parts by weight of activated calcium carbonate, 0.3 parts by weight of dimethylethanolamine and 150 parts by weight of water were stirred to obtain a suspension, 4.5 parts by weight of amino polysiloxane were added to the suspension, stirred at 60° C. and 600 rpm for 1 h, centrifuged, washed, and dried to obtain silane-modified calcium carbonate;

[0063] S2. Evenly mix 15 parts by weight of the modified calcium carbonate, 30 parts by weight of water, and 100 parts by weight of N,N-dimethylformamide, and then add 3 parts by weight of graphene oxide. Ultrasonicate for 30 minutes at an ultrasonic power of 200 W and an ultrasonic frequency of 60 kHz, and then stir at 90°C and 600 rpm for 40 minutes. Cool and filter, wash, dry, and grind to obtain a calcium-based powder material for PVC hard products.

[0064] The preparation method of the amino polysiloxane is as follows: under nitrogen protection, 10 parts by weight of γ-diethylenetriaminepropylmethyldimethoxysilane, 90 parts by weight of octamethylcyclotetrasiloxane, 10 parts by weight of methyloctadecyldiethoxysilane, 0.8 parts by weight of potassium hydroxide, and 3 parts by weight of water are mixed, pre-reacted at 90° C. for 3 hours, and then 2 parts by weight of (3-aminopropyl)dimethylmethoxysilane are added, and the reaction is continued for 40 hours, and reduced pressure distillation is performed to obtain the amino polysiloxane.

[0065] Comparative Example 2

[0066] A method for preparing a calcium-based powder material for PVC hard products comprises the following steps:

[0067] S1. Under nitrogen protection, 10 parts by weight of graphene oxide and 200 parts by weight of N,N-dimethylformamide were mixed, refluxed at 70°C for 8 hours, filtered, washed, 150 parts by weight of xylene were added, ultrasonicated at an ultrasonic power of 400W and an ultrasonic frequency of 60kHz for 40 minutes, 8 parts by weight of 4-hydroxybutyl acrylate and 1 part by weight of triethylamine were added, stirred at 30°C and 400rpm for 18 hours, filtered, washed, and dried to obtain functionalized graphene;

[0068] S2. Evenly mix 15 parts by weight of activated calcium carbonate, 30 parts by weight of water, and 100 parts by weight of N,N-dimethylformamide, and then add 3 parts by weight of functionalized graphene, ultrasonicate for 30 minutes at an ultrasonic power of 200 W and an ultrasonic frequency of 60 kHz, and then stir at 90°C and 600 rpm for 40 minutes, cool and filter, wash, dry, and grind to obtain a calcium-based powder material for PVC hard products.

[0069] Comparative Example 3

[0070] A method for preparing a calcium-based powder material for PVC hard products comprises the following steps:

[0071] S1, 20 parts by weight of activated calcium carbonate, 0.3 parts by weight of dimethylethanolamine and 150 parts by weight of water were stirred to obtain a suspension, 4.5 parts by weight of γ-diethylenetriaminepropylmethyldimethoxysilane was added to the suspension, stirred at 60° C. and 600 rpm for 1 h, centrifuged, washed, and dried to obtain silane-modified calcium carbonate;

[0072] S2. Under nitrogen protection, 10 parts by weight of graphene oxide and 200 parts by weight of N,N-dimethylformamide were mixed, refluxed at 70°C for 8 hours, filtered, washed, 150 parts by weight of xylene were added, ultrasonicated at an ultrasonic power of 400W and an ultrasonic frequency of 60kHz for 40 minutes, 8 parts by weight of 4-hydroxybutyl acrylate and 1 part by weight of triethylamine were added, stirred at 30°C and 400rpm for 18 hours, filtered, washed, and dried to obtain functionalized graphene;

[0073] S3. Evenly mix 15 parts by weight of the modified calcium carbonate, 30 parts by weight of water and 100 parts by weight of N,N-dimethylformamide, add 3 parts by weight of functionalized graphene, ultrasonicate for 30 minutes at an ultrasonic power of 200 W and an ultrasonic frequency of 60 kHz, stir at 90°C and 600 rpm for 40 minutes, cool and filter, wash, dry and grind to obtain a calcium-based powder material for PVC hard products.

[0074] Test Example 1

[0075] The calcium-based powder material for PVC hard products prepared in the above embodiments and comparative examples is applied to PVC hard products to test the influence of the device on the performance of PVC hard products. The preparation method of PVC hard products is as follows: 75 parts by weight of PVC resin, 15 parts by weight of calcium-based powder material for PVC hard products of the embodiments or comparative examples, 5 parts by weight of polyethylene glycol, 3 parts by weight of maleic anhydride grafted styrene, 1 part by weight of calcium-zinc composite stabilizer, and 1 part by weight of 3-(methacryloyloxy)propyltrimethoxysilane are mixed, the temperature is raised to 130°C, stirred at 1000 rpm for 1 hour, cooled, passed through a 60-mesh sieve, and injection molded to obtain a PVC hard product test specimen. The control group uses activated calcium carbonate instead of the calcium-based powder material for PVC hard products of the embodiments or comparative examples.

[0076] Tensile properties test: refer to the national standard GB / T1040.2-2022 "Determination of tensile properties of plastics Part 2: Test conditions for molded and extruded plastics" method for testing; the PVC hard product specimens in the embodiments and comparative examples were tested, and the test specimens were 1A dumbbell type, 4mm thick, and the test speed was 50mm / min. Before the test, the samples were thermostatically regulated at a temperature of 23°C and a relative humidity of 50% for 24 hours. Five parallel groups were tested and the average value was taken. The results are shown in Table 1.

[0077] Table 1 Tensile properties test results

[0078]

[0079] Test Example 2

[0080] Impact resistance: The test was conducted in accordance with the national standard GB / T 1843-2008 "Determination of cantilever beam impact strength of plastics". Before the test, the specimens were placed at a temperature of 23°C and a relative humidity of 50% for 20 hours. Notch type: Type A. Five parallel groups were tested and the average value was taken. The results are shown in Table 2.

[0081] Table 2 Impact resistance test results

[0082]

[0083] It can be seen from the above results that the calcium-based powder material for PVC hard products prepared by the present invention has good mechanical properties. The reason is that amino polysiloxane can be used to modify calcium carbonate to improve its compatibility and dispersibility in PVC. This modification method involves typing hydrophobic organic groups on the surface of inorganic particles, thereby reducing the surface energy and enhancing the compatibility and dispersibility of inorganic particles in organic systems. The surface properties of calcium carbonate can be effectively changed by using modifiers such as silane coupling agents. The coupling agent chemically reacts with the hydroxyl groups on the surface of calcium carbonate to introduce hydrophobic organic groups, thereby reducing its surface energy and making it easier to disperse in the PVC matrix. The modified calcium carbonate can not only improve the processing properties of PVC, but also enhance its mechanical properties, aging resistance, etc., thereby improving the quality and performance of the overall product.

[0084] The graphene-grafted cross-linked polymer contains hydrophilic hydroxyl groups and has good dispersibility in ethanol-water solution. The graphene-grafted cross-linked polymer contains 4-hydroxybutyl acrylate structural units, and its polymer molecular chain has excellent compatibility with polyvinyl chloride, so that graphene can be better dispersed in the polyvinyl chloride matrix, which has an excellent reinforcement effect and improves the tensile properties and Shore hardness of polyvinyl chloride. The introduction of functionalized graphene can improve the stiffness and strength of the material. In addition, the two-dimensional structure of functionalized graphene helps to disperse stress, thereby further improving the mechanical properties of the material.

[0085] Combining modified calcium carbonate and functionalized graphene can achieve a synergistic effect, and the mechanism is as follows: the combination of amino polysiloxane-modified calcium carbonate and functionalized graphene may improve the overall mechanical properties by enhancing the interfacial interaction between the filler and the PVC matrix; the combined use of the two fillers helps to achieve a more uniform filler dispersion in the PVC matrix and reduce agglomeration, thereby improving the performance of the material. Aminated polysiloxane-modified calcium carbonate provides good dispersibility and compatibility, while carboxylated graphene provides excellent mechanical reinforcement. The combination of the two achieves a reinforcement effect at multiple levels.

Claims

1. A method for preparing a calcium-based powder material for PVC hard products, characterized in that: The following steps are involved: S1, stirring a calcium-based material, dimethylethanolamine and water to obtain a suspension, adding amino polysiloxane to the suspension, heating and stirring, to obtain silane-modified calcium carbonate; S2, mixing graphene oxide and N,N-dimethylformamide and refluxing, filtering, washing, adding xylene for ultrasonication, then adding 4-hydroxybutyl acrylate and triethylamine for heating and stirring, filtering, washing, and drying to obtain functionalized graphene; S3, mixing the above-mentioned silane-modified calcium carbonate, water, and N,N-dimethylformamide evenly, adding functionalized graphene ultrasonically, heating and stirring, cooling and filtering, washing, drying, and grinding to obtain a calcium-based powder material for PVC hard products; The preparation method of the amino polysiloxane is as follows: under nitrogen protection, 8-12 parts by weight of γ-diethylenetriaminepropylmethyldimethoxysilane, 80-100 parts by weight of octamethylcyclotetrasiloxane, 7-12 parts by weight of methyloctadecyldiethoxysilane, 0.5-1 parts by weight of potassium hydroxide, and 2-8 parts by weight of water are mixed, pre-reacted at 85-110° C. for 2-5 hours, and then 1-3 parts by weight of (3-aminopropyl)dimethylmethoxysilane is added, the reaction is continued for 20-50 hours, and reduced pressure distillation is performed to obtain the amino polysiloxane.

2. The method for preparing the calcium-based powder material for PVC hard products according to claim 1, characterized in that: The calcium-based material is calcium carbonate.

3. The method for preparing the calcium-based powder material for PVC hard products according to claim 1, characterized in that: The heating temperature in S1 is 55-75° C., the stirring speed is 400-800 rpm, and the stirring time is 0.5-3 h.

4. The method for preparing the calcium-based powder material for PVC hard products according to claim 1, characterized in that: The reflux temperature in S2 is 68-80°C, and the reflux time is 5-10h; the ultrasonic power is 200-600W, the ultrasonic frequency is 40-80kHz, and the ultrasonic time is 30-60min; the heating temperature is 25-35°C, the stirring speed is 200-600rpm, and the stirring time is 12-30h.

5. The method for preparing calcium-based powder material for PVC hard products according to claim 1, characterized in that: The ultrasonic power in S3 is 100-300W, the ultrasonic frequency is 40-70kHz, and the ultrasonic time is 20-50min; the heating and stirring temperature is 85-100°C, the stirring speed is 400-800rpm, and the stirring time is 30-70min.

6. A calcium-based powder material for PVC hard products, characterized in that: The method is prepared by any one of claims 1 to 5.

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