Calcium-zinc composite stabilizer for PVC (polyvinyl chloride) and preparation process of calcium-zinc composite stabilizer

Abstract

The invention belongs to the technical field of stabilizers, and particularly relates to a calcium-zinc composite stabilizer for PVC and a preparation process. The calcium-zinc composite stabilizer for PVC is prepared from the following raw materials in parts by weight: 5-10 parts of calcium salt, 15-20 parts of zinc salt, 2-5 parts of a stabilizing auxiliary agent, 20-25 parts of a lubricant, 1-2 parts of an antioxidant and 2-4 parts of a silane coupling agent. The calcium-zinc composite stabilizer disclosed by the invention is excellent in thermal stability, is used for preparing the PVC foam board, and is good in foaming effect, and meanwhile, the mechanical property of the PVC foam board is excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of stabilizers, and particularly relates to a calcium-zinc composite stabilizer for PVC and a preparation process. Background Art

[0002] PVC (polyvinyl chloride) is a widely used thermoplastic, but due to its poor thermal stability during processing, stabilizers are usually added to prevent its decomposition. Calcium-zinc composite stabilizers are an environmentally friendly type of stabilizer and are widely used in PVC to replace traditional lead salts, cadmium soaps, and barium-cadmium-zinc composite stabilizers.

[0003] PVC foam board is a type of board formed by introducing gas into polyvinyl chloride material to form a microporous structure. This material is widely used in fields such as architectural decoration and industrial packaging due to its unique properties. When manufacturing PVC foam boards, high-temperature conditions are required to completely melt and plasticize the material. At the same time, due to the design characteristics of the mold (wide cross-section and long flow channel), and the fact that the blowing agent releases additional heat during decomposition, this places higher requirements on the heat stabilizer. Only when the heat stabilizer has sufficient thermal stability can it effectively cope with these high-temperature conditions, thereby ensuring that the produced boards meet the expected quality standards.

[0004] The existing calcium-zinc stabilizers in the art are mainly used to solve the thermal stability problem of PVC materials, but insufficient attention is often paid to the mechanical properties of the products after addition. At the same time, a higher foaming rate means that more gas is introduced into the material, thereby reducing the overall density of the material. Although a higher foaming rate can reduce weight, an excessively high foaming rate may affect the strength of the material. How to maintain good mechanical properties at a high foaming rate is a problem that needs to be solved currently.

[0005] Chinese Patent CN 107778727 A discloses a PVC micro-foamed floor environmental-friendly calcium-zinc stabilizer and its preparation method, which is composed of the following raw materials in mass percentages: 2-15% of calcium salt main stabilizer, 5-25% of zinc salt main stabilizer, 30-50% of hydrotalcite, 1-5% of antioxidant, 3-10% of auxiliary stabilizer, 5-20% of processing fluidity aid, 5-10% of heterocyclic compound, and 10-30% of lubricant, and has the advantages of good product stability, good product fluidity, uniform foaming, and low price.

[0006] Therefore, there is an urgent need for a calcium-zinc composite stabilizer and a preparation process specifically for PVC foam boards. Summary of the Invention

[0007] The purpose of the present invention is to provide a calcium-zinc composite stabilizer for PVC and a preparation process.

[0008] To achieve the above object, the present invention provides the following technical solutions: A calcium-zinc composite stabilizer for PVC, comprising the following raw materials in parts by weight: 5-10 parts of calcium salt, 15-20 parts of zinc salt, 2-5 parts of stabilizing auxiliary agent, 20-25 parts of lubricant, 1-2 parts of antioxidant, and 2-4 parts of silane coupling agent.

[0009] Further, the calcium salt includes at least one of calcium stearate, calcium palmitate, and calcium laurate.

[0010] Further, the calcium salt is calcium stearate.

[0011] Further, the zinc salt includes at least one of zinc stearate, zinc palmitate, and zinc laurate.

[0012] Further, the zinc salt is zinc stearate.

[0013] Further, the weight ratio of calcium stearate to zinc stearate is 1:2 to 1:2.5.

[0014] When the calcium-zinc composite stabilizer for PVC of the present invention uses calcium stearate as the calcium salt, zinc stearate as the zinc salt, and meets specific addition ratios at the same time, the prepared calcium-zinc composite stabilizer for PVC has good thermal stability and can improve the tensile strength of the PVC board. This is mainly because under these conditions, the zinc content in the composite stabilizer can avoid the "zinc burning" phenomenon, and an appropriate amount of calcium can provide long-term stability; at the same time, the long-chain structures of calcium stearate and zinc stearate increase the compatibility between the composite stabilizer and the components in the PVC foaming agent, reduce the intermolecular force of PVC, and have a better thermal stability effect. Calcium stearate and zinc stearate can form bridges between the PVC molecular chains, enhance the intermolecular interaction, and a reasonable calcium-zinc ratio helps to be evenly dispersed in the PVC matrix, avoiding performance non-uniformity caused by local excessive aggregation, thereby improving the tensile strength of the PVC foaming board.

[0015] Further, the stabilizing auxiliary agent includes epoxidized soybean oil, pentaerythritol, and polyethylene wax.

[0016] Furthermore, the stabilizing auxiliary agent includes epoxidized soybean oil, pentaerythritol, and polyethylene wax in a weight ratio of 1:(0.4-0.6):(1.2-1.5).

[0017] In the system of the present invention, a stabilizer auxiliary with a specific ratio is added, which can not only improve the thermal stability of the calcium-zinc composite stabilizer for PVC, but also improve the flexural strength of the PVC foam board. This is mainly because the epoxy soybean oil, pentaerythritol, and polyethylene wax with a specific ratio produce a synergistic effect. The epoxy soybean oil has a long-chain structure; pentaerythritol contains multiple hydroxyl functional groups and can react with the chlorine atoms on the PVC molecular chain; polyethylene wax can improve fluidity. Through the synergistic effect of multiple mechanisms, the internal structure and interfacial bonding force of the material are enhanced, and the flexural strength of the PVC foam board is improved.

[0018] Further, the lubricant is liquid paraffin.

[0019] Further, the antioxidant is selected from at least one of antioxidant 1010 and antioxidant 168.

[0020] Further, the silane coupling agent is selected from at least one of silane coupling agent KH792 and silane coupling agent KH602.

[0021] By adding a specific type of silane coupling agent to the calcium-zinc composite stabilizer for PVC, the present invention can improve the thermal stability and foaming ratio of the calcium-zinc composite stabilizer for PVC. The silane coupling agent used in the present invention is a diamino silane coupling agent with two active amino groups. These amino groups can react with the chlorine atoms or hydroxyl groups in the PVC matrix to form chemical bonds. This chemical bond can enhance the interfacial bonding force between the inorganic filler and the organic matrix. By enhancing the interfacial bonding force, the internal structure of the material becomes more uniform, thereby improving the overall thermal stability. Using a specific type of silane coupling agent in the present invention can promote the uniform dispersion of the blowing agent in the PVC matrix, making the bubble nuclei more evenly distributed, thereby improving the foaming ratio and cell uniformity, forming a three-dimensional network structure in the PVC melt, increasing the viscosity and strength of the melt, helping to maintain the cell shape, preventing cell coalescence or rupture, and thus improving the foaming ratio.

[0022] The present invention also provides a preparation process for the calcium-zinc composite stabilizer for PVC, including the following steps: stirring calcium salt, zinc salt, and lubricant at 60 - 65 °C for 10 min - 15 min; then adding the remaining raw materials and stirring at 60 - 65 °C for 15 min - 20 min, and obtaining the calcium-zinc composite stabilizer for PVC after cooling.

[0023] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. When calcium stearate is used as the calcium salt, zinc stearate is used as the zinc salt, and specific addition ratios are simultaneously met in the calcium-zinc composite stabilizer for PVC of the present invention, the prepared calcium-zinc composite stabilizer for PVC has good thermal stability and can improve the tensile strength of the PVC board.

[0024] 2. In the system of the present invention, a stabilizing auxiliary agent with a specific ratio is added, which can not only improve the thermal stability of the calcium-zinc composite stabilizer for PVC, but also improve the bending strength of the PVC foamed board.

[0025] 3. By adding a silane coupling agent of a specific model to the calcium-zinc composite stabilizer for PVC, the present invention can improve the thermal stability of the composite stabilizer and the foaming ratio of the PVC foamed board. Detailed implementation manners

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0027] All raw materials used in the following embodiments of the present invention are commercially available products: Silane coupling agent KH792, Nanjing Chemical Reagent Co., Ltd.

[0028] Epoxidized soybean oil, Shandong Xinrongxin Chemical Technology Co., Ltd., industrial grade.

[0029] Polyethylene wax, Shandong Baolilai Plastic Auxiliary Co., Ltd., molecular weight 1500 - 5000.

[0030] Liquid paraffin, Changde Hengtong Petrochemical Auxiliary Co., Ltd.

[0031] Antioxidant 1010, Nantong Xinchang Chemical Co., Ltd.

[0032] Example 1 This example provides a calcium-zinc composite stabilizer for PVC, which comprises the following raw materials in parts by weight: 8 parts of calcium salt, 16 parts of zinc salt, 4 parts of stabilizing auxiliary agent, 22 parts of lubricant, 1.4 parts of antioxidant, and 3 parts of silane coupling agent.

[0033] The zinc salt is zinc stearate; the calcium salt is calcium stearate.

[0034] The stabilizing auxiliary agent comprises epoxidized soybean oil, pentaerythritol, and polyethylene wax in a weight ratio of 1:0.5:1.3.

[0035] The lubricant is liquid paraffin; the antioxidant is antioxidant 1010.

[0036] The silane coupling agent is silane coupling agent KH792.

[0037] The preparation process of the calcium-zinc composite stabilizer for PVC includes the following steps: Stir calcium salt, zinc salt, and lubricant at 65 °C for 10 min; then add the remaining raw materials and stir at 65 °C for 20 min. After cooling, the calcium-zinc composite stabilizer for PVC is obtained.

[0038] Example 2 This example provides a calcium-zinc composite stabilizer for PVC, which includes the following raw materials in parts by weight: 9 parts of calcium salt, 20 parts of zinc salt, 5 parts of stabilizing auxiliary agent, 25 parts of lubricant, 1 part of antioxidant, and 4 parts of silane coupling agent.

[0039] The zinc salt is zinc stearate; the calcium salt is calcium stearate.

[0040] The stabilizing auxiliary agent includes epoxy soybean oil, pentaerythritol, and polyethylene wax in a weight ratio of 1:0.4:1.2.

[0041] The lubricant is liquid paraffin; the antioxidant is antioxidant 1010.

[0042] The silane coupling agent is silane coupling agent KH792.

[0043] The preparation process of the calcium-zinc composite stabilizer for PVC includes the following steps: Stir calcium salt, zinc salt, and lubricant at 65 °C for 10 min; then add the remaining raw materials and stir at 65 °C for 20 min. After cooling, the calcium-zinc composite stabilizer for PVC is obtained.

[0044] Example 3 The difference between this example and Example 1 is the different parts of calcium salt and zinc salt.

[0045] A calcium-zinc composite stabilizer for PVC includes the following raw materials in parts by weight: 5 parts of calcium salt, 19 parts of zinc salt, 4 parts of stabilizing auxiliary agent, 22 parts of lubricant, 1.4 parts of antioxidant, and 3 parts of silane coupling agent.

[0046] The zinc salt is zinc stearate; the calcium salt is calcium stearate.

[0047] The stabilizing auxiliary agent includes epoxy soybean oil, pentaerythritol, and polyethylene wax in a weight ratio of 1:0.5:1.3.

[0048] The lubricant is liquid paraffin; the antioxidant is antioxidant 1010.

[0049] The silane coupling agent is silane coupling agent KH792.

[0050] The preparation process of the calcium-zinc composite stabilizer for PVC includes the following steps: Stir calcium salt, zinc salt, and lubricant at 65 °C for 10 min; then add the remaining raw materials and stir at 65 °C for 20 min. After cooling, the calcium-zinc composite stabilizer for PVC is obtained.

[0051] Example 4 The difference between this example and Example 1 is that the types of calcium salt and zinc salt are different.

[0052] A calcium-zinc composite stabilizer for PVC is provided, which includes the following raw materials in parts by weight: 8 parts of calcium salt, 16 parts of zinc salt, 4 parts of stabilizing auxiliary agent, 22 parts of lubricant, 1.4 parts of antioxidant, and 3 parts of silane coupling agent.

[0053] The zinc salt is zinc laurate; the calcium salt is calcium laurate.

[0054] The stabilizing auxiliary agent includes epoxidized soybean oil, pentaerythritol, and polyethylene wax in a weight ratio of 1:0.5:1.3.

[0055] The lubricant is liquid paraffin; the antioxidant is antioxidant 1010.

[0056] The silane coupling agent is silane coupling agent KH792.

[0057] The preparation process of the calcium-zinc composite stabilizer for PVC includes the following steps: Stir calcium salt, zinc salt, and lubricant at 65 °C for 10 min; then add the remaining raw materials and stir at 65 °C for 20 min. After cooling, the calcium-zinc composite stabilizer for PVC is obtained.

[0058] Example 5 The difference between this example and Example 1 is that the stabilizing auxiliary agent includes epoxidized soybean oil, pentaerythritol, and polyethylene wax in a weight ratio of 0.5:1.3:1.

[0059] A calcium-zinc composite stabilizer for PVC includes the following raw materials in parts by weight: 8 parts of calcium salt, 16 parts of zinc salt, 4 parts of stabilizing auxiliary agent, 22 parts of lubricant, 1.4 parts of antioxidant, and 3 parts of silane coupling agent.

[0060] The zinc salt is zinc stearate; the calcium salt is calcium stearate.

[0061] The stabilizing auxiliary agent includes epoxidized soybean oil, pentaerythritol, and polyethylene wax in a weight ratio of 0.5:1.3:1.

[0062] The lubricant is liquid paraffin; the antioxidant is antioxidant 1010.

[0063] The silane coupling agent is silane coupling agent KH792.

[0064] The preparation process of the calcium-zinc composite stabilizer for PVC includes the following steps: Stir calcium salt, zinc salt, and lubricant at 65 °C for 10 min; then add the remaining raw materials and stir at 65 °C for 20 min. After cooling, the calcium-zinc composite stabilizer for PVC is obtained.

[0065] Comparative Example 1 The difference between this comparative example and Example 1 is that the stabilizing co-agent is epoxidized soybean oil.

[0066] Comparative Example 2 The difference between this comparative example and Example 1 is that the stabilizing co-agent is pentaerythritol.

[0067] Comparative Example 3 The difference between this comparative example and Example 1 is that the stabilizing co-agent is polyethylene wax.

[0068] Comparative Example 4 The difference between this comparative example and Example 1 is that no silane coupling agent is added.

[0069] Comparative Example 5 The difference between this comparative example and Example 1 is that the silane coupling agent is replaced with silane coupling agent KH550.

[0070] Comparative Example 6 The difference between this comparative example and Example 1 is that the calcium-zinc composite stabilizer for PVC is a commercially available product, specifically: an environmentally friendly composite stabilizer for PVC hard products, model TF-720A, from Zhejiang Chuanhua Huayang Chemical Co., Ltd.

[0071] Comparative Example 7 The difference between this comparative example and Example 1 is that Chinese Patent CN 107778727 A discloses a calcium-zinc stabilizer for PVC micro-foamed floor and its preparation method, and the calcium-zinc stabilizer prepared in Example 1.

[0072] Performance Test The composition of the PVC foamed board includes the following raw materials by weight: 80 parts of PVC resin (SG-5, from Shandong Aokai Chemical Co., Ltd.), 25 parts of calcium carbonate, 1.5 parts of ACR blowing agent (azodicarbonamide), 9 parts of blowing stabilizing co-agent (general ACR-401, from Hongming New Materials Technology (Shandong) Co., Ltd.), and 2.5 parts of the calcium-zinc composite stabilizer prepared in Examples 1-5 / Comparative Examples 1-7 of the present invention.

[0073] Accurately weigh the raw materials, then mix them evenly and knead on a two-roll mill at 185 °C for 5 min to make a sample with a thickness of 1 mm.

[0074] 1. Congo Red Experiment (PVC Static Thermal Stability): Tested according to GB / T2917.1-2002, controlling the oil bath temperature at 185°C, and measuring the time elapsed until the Congo Red test paper turns blue, which is the stabilization time.

[0075] 2. Place the sample in a 200°C heat aging oven for foaming, take a sample at the 120th second, measure the thickness of the test piece after cooling, and calculate the foaming ratio. The calculation formula is: thickness after foaming ÷ thickness before foaming.

[0076] 3. Refer to GB / T 1040.2-2022 to measure the tensile strength and flexural strength of the test specimen.

[0077] The results are shown in Table 1.

[0078] Table 1 Performance Test Results Test Congo red time min Foaming ratio Tensile strength MPa Flexural strength MPa Example 1 167 3.3 51.6 50.3 Example 2 161 3.2 50.7 49.2 Example 3 135 3.0 48.2 47.7 Example 4 137 3.1 48.5 47.1 Example 5 142 3.0 47.1 46.5 Comparative example 1 128 2.8 42.8 40.2 Comparative example 2 121 2.7 44.4 42.4 Comparative example 3 125 2.8 43.6 41.8 Comparative example 4 119 2.6 40.3 39.0 Comparative example 5 138 2.9 46.9 45.3 Comparative example 6 105 2.6 45.4 43.7 Comparative example 7 114 2.4 48.7 47.4 It can be seen from Table 1 that the calcium-zinc composite stabilizer for PVC prepared in Examples 1-2 has excellent thermal stability. At the same time, the PVC foam board prepared with it has a high foaming ratio and good mechanical properties, which can achieve the balance of the two and overall improve the use performance of the calcium-zinc composite stabilizer for PVC.

[0079] In Example 3, the proportions of calcium salt and zinc salt are different, and in Example 4, the types of calcium salt and zinc salt are different. It can be found that the thermal stability is lower than that of Example 1, and at the same time, the tensile properties of the PVC foam board are lower than those of Example 1.

[0080] In Example 5, the ratios of epoxidized soybean oil, pentaerythritol, and polyethylene wax used in the stabilizing auxiliary agent are different. Compared with Example 1, the thermal stability of the calcium-zinc composite stabilizer for PVC decreases, and the flexural strength of the PVC foam board decreases, indicating that only at specific ratios can epoxidized soybean oil, pentaerythritol, and polyethylene wax achieve better synergistic effects. The specific ratios of epoxidized soybean oil, pentaerythritol, and polyethylene wax used in Example 1 produce synergistic effects. Epoxidized soybean oil has a long-chain structure; pentaerythritol contains multiple hydroxyl functional groups and can react with chlorine atoms on the PVC molecular chain; polyethylene wax can improve fluidity. Through the synergistic effects of multiple mechanisms, the internal structure and interfacial bonding force of the material are enhanced, and the flexural strength of the PVC foam board is improved.

[0081] In Comparative Examples 1 to 3, a single type of stabilizing auxiliary agent was used. Compared with Example 1, the thermal stability of the calcium-zinc composite stabilizer for PVC decreased, and the flexural strength of the PVC foam board decreased. This shows that when using a single type of stabilizing auxiliary agent in the present invention, the improvement effect of the flexural strength of the PVC foam board is not ideal. The chain lengths of calcium stearate and zinc stearate in Example 1 are greater than those of zinc laurate and calcium laurate used in Example 4. Calcium stearate and zinc stearate increase the compatibility between the composite stabilizer and the components in the PVC foaming agent, reduce the intermolecular force of PVC, and have a better thermal stability effect. Calcium stearate and zinc stearate can form a bridge between the PVC molecular chains, enhance the intermolecular interaction, and a reasonable calcium-zinc ratio helps to disperse uniformly in the PVC matrix, avoiding performance inhomogeneity caused by local over-aggregation, thereby improving the tensile strength of the PVC foam board.

[0082] In Comparative Example 4, no silane coupling agent was added, and the thermal stability of the composite stabilizer, the foaming ratio of the PVC foam board decreased.

[0083] In Comparative Example 5, a silane coupling agent with one amino group was used, and the improvement effect on the thermal stability of the composite stabilizer, the foaming ratio of the PVC foam board was lower than that of Example 1. This shows that the silane coupling agent with two amino groups has a better improvement effect on the system compatibility of the present invention and a better improvement effect on the foaming effect. The silane coupling agent used in Example 1 is a silane coupling agent with two amino groups, which has two active amino groups. These amino groups can react with chlorine atoms or hydroxyl groups in the PVC matrix to form chemical bonds. This chemical bond can enhance the interfacial bonding force between the inorganic filler and the organic matrix. By enhancing the interfacial bonding force, the internal structure of the material becomes more uniform, thereby improving the overall thermal stability. Using a specific type of silane coupling agent in Example 1 can promote the uniform dispersion of the foaming agent in the PVC matrix, making the bubble nuclei easier to be evenly distributed, thereby increasing the foaming ratio and the uniformity of the cell structure, forming a three-dimensional network structure in the PVC melt, increasing the viscosity and strength of the melt, helping to maintain the cell shape, preventing cell coalescence or rupture, and thus increasing the foaming ratio.

[0084] In Comparative Example 6, a commercially available composite stabilizer was used, and the foaming ratio was lower than that of Example 1 of the present invention, and the mechanical properties were not ideal.

[0085] In Comparative Example 7, a composite stabilizer prepared by the prior art was used, and its thermal stability was lower than that of Example 1.

[0086] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A calcium-zinc composite stabilizer for PVC, characterized in that: The invention comprises the following raw materials in parts by weight: 5-10 parts of calcium salt, 15-20 parts of zinc salt, 2-5 parts of stabilizing auxiliary agent, 20-25 parts of lubricant, 1-2 parts of antioxidant and 2-4 parts of silane coupling agent.

2. The calcium-zinc composite stabilizer for PVC according to claim 1, characterized in that: The calcium salt includes at least one of calcium stearate, calcium palmitate and calcium laurate.

3. The calcium-zinc composite stabilizer for PVC according to claim 1, characterized in that: The zinc salt includes at least one of zinc stearate, zinc palmitate and zinc laurate.

4. The calcium-zinc composite stabilizer for PVC according to claim 1, characterized in that: The zinc salt is zinc stearate; the calcium salt is calcium stearate.

5. The calcium-zinc composite stabilizer for PVC according to claim 4, characterized in that: The weight ratio of the calcium stearate to the zinc stearate is 1:2 to 1:2.

5.

6. The calcium-zinc composite stabilizer for PVC according to claim 1, characterized in that: The stabilizing auxiliary agents include epoxidized soybean oil, pentaerythritol and polyethylene wax.

7. The calcium-zinc composite stabilizer for PVC according to claim 6, characterized in that: The stabilizing auxiliary agent comprises epoxy soybean oil, pentaerythritol and polyethylene wax in a weight ratio of 1: (0.4-0.6): (1.2-1.5).

8. The calcium-zinc composite stabilizer for PVC according to claim 1, characterized in that: The lubricant is liquid paraffin; the antioxidant is selected from at least one of antioxidant 1010 and antioxidant 168.

9. The calcium-zinc composite stabilizer for PVC according to claim 1, characterized in that: The silane coupling agent is selected from at least one of silane coupling agent KH792 and silane coupling agent KH602.

10. A process for preparing the calcium-zinc composite stabilizer for PVC according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: stirring calcium salt, zinc salt and lubricant at 60-65°C for 10-15 min; then adding the remaining raw materials, stirring at 60-65°C for 15-20 min, and cooling to obtain a calcium-zinc composite stabilizer for PVC.