Halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, preparation method thereof and application of halogen-antimony synergistic low-smoke heat-resistant composite flame retardant in flame-retardant modification of soft PVC artificial leather

Abstract

The invention provides a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, a preparation method thereof and application of the halogen-antimony synergistic low-smoke heat-resistant composite flame retardant in flame-retardant modification of soft PVC artificial leather, and belongs to the technical field of high polymer material auxiliaries. The composite flame retardant is prepared by compounding the following components in parts by weight: 15-25 parts of antimony trioxide, 30-40 parts of chlorinated paraffin, 8-12 parts of a smoke suppressant, 2-5 parts of a nucleating agent, 20-30 parts of heat-resistant inorganic filler and 1-3 parts of a surface modifier. Through a preparation process of powder pretreatment and multi-component premixing, and in combination with a surface modification technology, synergistic improvement of flame retardance, smoke suppression, heat resistance and processability is realized, the hand feeling and mechanical properties of the soft PVC artificial leather are not influenced, and the soft PVC artificial leather can be widely applied to the fields of furniture, clothing, bags, decoration and the like, and has good industrial practicability and market promotion value.

Description

Technical Field

[0001] This invention relates to the field of polymer material additives technology, and in particular to a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, its preparation method, and its application in the flame-retardant modification of soft PVC artificial leather. Background Technology

[0002] PVC (polyvinyl chloride) artificial leather is widely used in furniture, clothing, bags, decoration, and other industries due to its excellent properties such as softness, wear resistance, low cost, and ease of processing and molding. However, PVC resin itself is a flammable polymer material that releases a large amount of toxic and harmful fumes and corrosive gases during combustion. Furthermore, its poor heat resistance and low heat distortion temperature make it prone to softening and deformation at high temperatures. This inherent defect severely limits the application of PVC artificial leather in high-end fields and areas with high safety requirements.

[0003] Currently, commonly used flame retardants for PVC artificial leather are mainly divided into two categories: halogenated flame retardants and halogen-free flame retardants. Among them, halogenated flame retardants have become the most widely used type of flame retardant in industrial applications due to their high flame retardant efficiency and low raw material cost. The halogen-antimony synergistic system composed of chlorinated paraffin and antimony trioxide is widely used in the flame retardant modification of PVC materials due to its significant synergistic flame retardant effect and high cost-effectiveness. However, the traditional halogen-antimony flame retardant system has many technical defects: high smoke density and high release of toxic fumes during combustion, posing secondary safety hazards; limited improvement on the heat resistance of PVC materials, unable to meet the needs of high-temperature applications; and poor compatibility between inorganic flame retardant fillers and PVC resin, which can easily lead to a hardening of the PVC artificial leather's feel and a decrease in its mechanical properties after addition.

[0004] To address the aforementioned issues, existing technologies often improve the overall performance of flame retardants by compounding smoke suppressants and heat-resistant fillers. However, most compound systems suffer from drawbacks such as unreasonable component matching, poor synergistic effects between components, and unsatisfactory processing performance, making it difficult to simultaneously meet the multiple requirements of PVC artificial leather for flame retardancy, smoke suppression, heat resistance, and processing performance. Therefore, developing a composite flame retardant with high flame retardant efficiency, low smoke density, good heat resistance, and processing friendliness, and which does not affect the feel and mechanical properties of PVC artificial leather after addition, has significant practical importance and market application value. Summary of the Invention

[0005] The purpose of this invention is to provide a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, its preparation method, and its application in the flame-retardant modification of soft PVC artificial leather, so as to solve the technical problems of high smoke density, poor heat resistance, poor compatibility between inorganic fillers and resin, and poor synergistic effect of the compound system in the existing halogen-antimony flame retardant system for PVC artificial leather.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, prepared from raw materials comprising the following parts by weight: Antimony trioxide 15-25 parts, chlorinated paraffin 30-40 parts, smoke suppressant 8-12 parts, nucleating agent 2-5 parts, heat-resistant inorganic filler 20-30 parts, surface modifier 1-3 parts; The smoke suppressant is a complex of zinc borate and zinc molybdate.

[0007] Furthermore, the weight ratio of zinc borate to zinc molybdate is 1:1 to 2:1.

[0008] Furthermore, the nucleating agent is talc powder, wherein the silica content of the talc powder is ≥50% and the particle size D50 is 4~6μm.

[0009] Furthermore, the heat-resistant inorganic filler is ultrafine magnesium hydroxide prepared by physical grinding of brucite as the raw ore, with a particle size D50 of 1.2μm~3.5μm; the surface modifier is a silane coupling agent.

[0010] Furthermore, the purity of the antimony trioxide is ≥99.8%; the chlorine content in the chlorinated paraffin is ≥70%, and the viscosity of the chlorinated paraffin at 25°C is 150~250 mPa·s.

[0011] This invention also provides a method for preparing a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, comprising the following steps: 1) After mixing antimony trioxide, smoke suppressant, nucleating agent and heat-resistant inorganic filler, the mixture is heated, and then a surface modifier is added and mixed to activate the powder surface. 2) After cooling the activated powder, add chlorinated paraffin and mix evenly to obtain a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant.

[0012] Furthermore, in step 1), the heating temperature is 90~110℃, the mixing speed after adding the surface modifier is 800~1200r / min, and the mixing time is 10~30min.

[0013] Furthermore, in step 2), the cooling temperature is 60~80℃, the mixing speed of the added chlorinated paraffin is 400~600 r / min, and the mixing time is 6~20 min.

[0014] This invention also provides an application of a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant in the flame retardant modification of soft PVC artificial leather.

[0015] The beneficial effects of this invention are: (a) Technical benefits: 1. Synergistic improvement of multiple performances: This invention solves the three major technical problems of traditional halogen-antimony flame retardant systems—high smoke density, poor heat resistance, and poor compatibility—through reasonable component compounding and surface modification processes. At the same time, it achieves synergistic improvement of flame retardancy, smoke suppression, heat resistance, and processing performance, filling the gap in existing technologies that cannot simultaneously meet the multiple performance requirements of PVC artificial leather.

[0016] 2. Significant synergistic effect of components: The combination of zinc borate and zinc molybdate in the smoke suppressant, and the combination of halogen-antimony system with nucleating agent / heat-resistant filler, create a complementary and synergistic effect among the components, which greatly improves the flame retardant and smoke suppressant effect; the use of surface modifier fundamentally solves the compatibility problem between inorganic filler and PVC resin, avoiding the decline in material feel and mechanical properties.

[0017] 3. Simple and efficient preparation process: The preparation method of the present invention only includes two steps: powder pretreatment and multi-component premixing. The process parameters are easy to control, no complex special equipment is required, it can be adapted to industrial continuous production, and no toxic or harmful substances are generated during the production process, which meets the requirements of green production.

[0018] (II) Economic Benefits: 1. Low cost and readily available raw materials: The raw materials selected in this invention, such as antimony trioxide, chlorinated paraffin-70, talc, and magnesium hydroxide, are all commonly used industrial chemical raw materials. They are widely available and inexpensive in the market. Moreover, the proportion of the formula components is reasonable, and there are no expensive or rare raw materials, which greatly reduces the production cost of composite flame retardants.

[0019] 2. Adaptable to existing processing technology: The composite flame retardant of the present invention can be directly added to the existing PVC artificial leather preparation system without modifying the production equipment and processing technology, which reduces the application and modification costs for enterprises and facilitates industrial promotion and application.

[0020] 3. Enhance product added value: PVC artificial leather with the addition of the composite flame retardant of this invention has significantly improved flame retardancy, smoke suppression and heat resistance. It can break through the limitations of the original application fields and enter fields with high safety requirements such as high-end furniture, automotive interiors and high-end interior decoration, which greatly enhances the added value and market competitiveness of PVC artificial leather products.

[0021] (III) Social Benefits: 1. Reduce fire safety hazards: The composite flame retardant of this invention can effectively improve the flame retardant performance of PVC artificial leather, reduce the release of toxic and harmful fumes and dripping phenomena during combustion, and significantly reduce the probability of fire and the speed of fire spread during the use of PVC artificial leather products, thus ensuring personal and property safety.

[0022] 2. Expanding the application fields of PVC materials: This invention solves the core defects of PVC artificial leather, such as poor heat resistance and insufficient flame retardancy, expands its application in high-end fields, improves the resource utilization rate of PVC polymer materials, and promotes the industrial upgrading and high-quality development of the PVC industry.

[0023] 3. In line with environmental protection development trends: The composite flame retardant of the present invention not only improves flame retardant performance, but also significantly reduces smoke density and toxic smoke release during combustion. Moreover, the preparation process is green and environmentally friendly, which is in line with the current low-carbon, environmentally friendly and safe development trend of the chemical industry and has good environmental friendliness.

[0024] (iv) Industrial applicability: The halogen-antimony synergistic low-smoke heat-resistant composite flame retardant of this invention has a simple preparation process, readily available raw materials, and low cost, enabling large-scale industrial production. Its addition does not affect the soft feel and excellent mechanical properties of PVC artificial leather, and it is compatible with existing processing techniques such as calendering and extrusion of soft PVC artificial leather, making it convenient to use. The prepared PVC artificial leather exhibits excellent flame retardant, smoke suppression, and heat resistance properties, and can be widely used in furniture, clothing, bags, decoration, and other fields. It solves the application limitations of traditional PVC artificial leather in high-end safety fields, possessing extremely high industrial practicality and market promotion value. Detailed Implementation

[0025] This invention provides a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, prepared from raw materials comprising the following parts by weight: Antimony trioxide 15-25 parts, chlorinated paraffin 30-40 parts, smoke suppressant 8-12 parts, nucleating agent 2-5 parts, heat-resistant inorganic filler 20-30 parts, surface modifier 1-3 parts; The smoke suppressant is a complex of zinc borate and zinc molybdate.

[0026] In this invention, the content of antimony trioxide is preferably 18 to 22 parts by weight, and more preferably 20 parts by weight.

[0027] In this invention, the antimony trioxide has a purity of ≥99.8%. As the core flame-retardant component of the halogen-antimony synergistic system, it has good gas-phase free radical capture ability and can form a highly efficient halogen-antimony synergistic flame-retardant system with chlorinated paraffin, providing core support for flame-retardant performance.

[0028] In this invention, the content of chlorinated paraffin is preferably 32-38 parts by weight, more preferably 34-36 parts. The chlorinated paraffin has a viscosity of 150-250 mPa·s at 25°C and a chlorine content ≥70%. It not only has excellent flame-retardant properties but also plasticizing effects, improving the processing performance and flexibility of PVC artificial leather and ensuring the soft feel of the soft PVC artificial leather.

[0029] In this invention, the smoke suppressant content is preferably 9-11 parts by weight, more preferably 10 parts. The smoke suppressant is a composite of zinc borate and zinc molybdate, with a weight ratio of 1:1 to 2:1, preferably 1:1. Zinc borate has good smoke suppression and smoldering suppression effects, while zinc molybdate can promote the formation of a dense char layer during PVC combustion. The combination of the two can significantly reduce smoke density and the release of toxic fumes during combustion, while further enhancing the synergistic flame-retardant effect with the halogen-antimony system.

[0030] In this invention, the nucleating agent is preferably 3-4 parts by weight, more preferably 3.5 parts. The nucleating agent is talc powder with a silica content ≥50% and a particle size D50 of 4-6 μm. Talc powder can promote the formation of a dense, continuous char layer from PVC resin during combustion, reduce dripping, and improve the heat insulation and oxygen barrier properties of the char layer, thus enhancing the flame retardant effect. Furthermore, the raw material is readily available and inexpensive, and it can also improve the processing fluidity of the composite system.

[0031] In this invention, the content of the heat-resistant inorganic filler is preferably 22-28 parts by weight, more preferably 24-26 parts. The heat-resistant inorganic filler is ultrafine magnesium hydroxide prepared by physical grinding of brucite ore, with a particle size D50 of 1.2μm-3.5μm, preferably 1.5-2μm. The ultrafine magnesium hydroxide prepared by physical grinding retains the natural properties of brucite ore, exhibiting excellent heat absorption and cooling effects. During combustion, it can absorb a large amount of heat, inhibiting the thermal decomposition of PVC resin, while also assisting in smoke suppression and increasing the heat distortion temperature of the material. The ultrafine particle size can significantly improve its compatibility with PVC resin, avoiding any impact on the feel and mechanical properties of artificial leather.

[0032] In this invention, the content of the surface modifier is preferably 1.5 to 2.5 parts by weight, more preferably 2 parts. The surface modifier is a silane coupling agent, selected from at least one of aminosilane coupling agents, epoxysilane coupling agents, and vinylsilane coupling agents. The silane coupling agent can chemically react with the hydroxyl groups on the surface of the inorganic powder to form an organic coating layer on the powder surface, improving the dispersibility of the inorganic phase in PVC resin, enhancing the interfacial bonding force between the inorganic and organic phases, thereby improving the mechanical and processing properties of the composite system and meeting the processing requirements of soft PVC artificial leather.

[0033] This invention also provides a method for preparing a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, comprising the following steps: 1) After mixing antimony trioxide, smoke suppressant, nucleating agent and heat-resistant inorganic filler, the mixture is heated, and then a surface modifier is added and mixed to activate the powder surface. 2) After cooling the activated powder, add chlorinated paraffin and mix evenly to obtain a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant.

[0034] In this invention, in step 1), the heating temperature is 90~110℃, preferably 105℃; the mixing speed after adding the surface modifier is 800~1200r / min, preferably 900~1100r / min, and more preferably 1050r / min; the mixing time is 10~30min, preferably 15~20min.

[0035] In this invention, surface activation of the powder is used to improve the compatibility between the inorganic powder and the organic phase, and to avoid uneven dispersion in subsequent applications.

[0036] In this invention, in step 2), the cooling temperature is 60~80℃, preferably 65~75℃, and more preferably 70℃; the mixing speed of the added chlorinated paraffin is 400~600 r / min, preferably 500 r / min; and the mixing time is 6~20 min, preferably 10~15 min.

[0037] This invention also provides an application of a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant in the flame retardant modification of soft PVC artificial leather.

[0038] The composite flame retardant of the present invention is mainly used for flame retardant modification of soft PVC artificial leather. It can be directly added to the raw material system for the preparation of PVC artificial leather in proportion. It is compatible with existing PVC artificial leather extrusion, calendering and other processing technologies, without the need to modify production equipment and process parameters.

[0039] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0040] The experimental materials used in the following examples: Antimony trioxide: purity ≥99.8%, commercially available; Zinc borate and zinc molybdate: industrial grade, commercially available; Chlorinated paraffin-70: viscosity at 25℃ 150~250mPa·s, chlorine content ≥70%, commercially available; Talc HS-658 (D50: 5-5.5μm, SiO2≥50%), HS-368 (D50: 7-8.5μm, SiO2≥50%): Haicheng Xinguangyuan Powder Materials Co., Ltd. Ultrafine magnesium hydroxide GY-3000 (D50: 3.0-3.3μm), GY-6000 (D50: 1.3-1.8μm), GY-1250 (D50: 4.3-4.5μm), GY-2000 (D50: 3.6-3.8μm), GY-800 (D50: 6-8μm): Haicheng Xinguangyuan Powder Materials Co., Ltd. Silane coupling agent R-903 (compound type): Foshan Putuobao Chemical Co., Ltd.

[0041] Example 1

[0042] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-3000, and 12 kg of silane coupling agent R-903, and feed them into a high-speed mixer for surface modification treatment; the modification temperature is 105℃, the modification time is 15 min, and the stirring speed is 1050 r / min; cool the modified powder to 70℃, add 350 kg of chlorinated paraffin-70, and continue stirring at 500 r / min for 8 min to prepare composite flame retardant powder.

[0043] Example 2

[0044] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-3000, and 15 kg of silane coupling agent R-903, and feed them into a high-speed mixer for surface modification treatment; the modification temperature is 105℃, the modification time is 15 min, and the stirring speed is 1050 r / min; cool the modified powder to 70℃, add 350 kg of chlorinated paraffin-70, and continue stirring at 500 r / min for 8 min to prepare composite flame retardant powder.

[0045] Example 3

[0046] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-3000, and 15 kg of silane coupling agent R-903, and feed them into a high-speed mixer for surface modification treatment; the modification temperature is 105℃, the modification time is 15 min, and the stirring speed is 1050 r / min; cool the modified powder to 70℃, add 350 kg of chlorinated paraffin-70, and continue stirring at 500 r / min for 8 min to prepare composite flame retardant powder.

[0047] Example 4

[0048] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-6000, and 12 kg of silane coupling agent R-903, and feed them into a high-speed mixer for surface modification treatment; the modification temperature is 105℃, the modification time is 15 min, and the stirring speed is 1050 r / min; cool the modified powder to 70℃, add 350 kg of chlorinated paraffin-70, and continue stirring at 500 r / min for 8 min to prepare composite flame retardant powder.

[0049] Example 5

[0050] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-6000, and 15 kg of silane coupling agent R-903, and feed them into a high-speed mixer for surface modification treatment; the modification temperature is 105℃, the modification time is 15 min, and the stirring speed is 1050 r / min; cool the modified powder to 70℃, add 350 kg of chlorinated paraffin-70, and continue stirring at 500 r / min for 8 min to prepare composite flame retardant powder.

[0051] Example 6

[0052] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-6000, and 18 kg of silane coupling agent R-903, and feed them into a high-speed mixer for surface modification treatment; the modification temperature is 105℃, the modification time is 15 min, and the stirring speed is 1050 r / min; cool the modified powder to 70℃, add 350 kg of chlorinated paraffin-70, and continue stirring at 500 r / min for 8 min to prepare composite flame retardant powder.

[0053] Comparative Example 1

[0054] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-1250, and 15 kg of silane coupling agent R-903, and prepare composite powder according to the process in Example 1.

[0055] Comparative Example 2

[0056] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-2000, and 15 kg of silane coupling agent R-903, and prepare composite powder according to the process in Example 1.

[0057] Comparative Example 3

[0058] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-658, 280 kg of magnesium hydroxide GY-800, and 15 kg of silane coupling agent R-903, and prepare composite powder according to the process in Example 1.

[0059] Comparative Example 4

[0060] Weigh out 160 kg of antimony trioxide, 50 kg of zinc borate, 50 kg of zinc molybdate, 30 kg of talc powder HS-368, 280 kg of magnesium hydroxide GY-6000, and 15 kg of silane coupling agent R-903, and prepare composite powder according to the process in Example 1.

[0061] The flame retardants prepared in Examples 1-6 and Comparative Examples 1-4 were applied to flexible PVC materials. The experimental formula (parts by weight) was as follows: PVC (SG-5 type, Cangzhou Julong Chemical) 100g, DOTP (Zhonghang New Materials (Shandong)) 90g, liquid barium cadmium zinc composite stabilizer (Wenzhou Zhengbang Chemical) 8g, calcium carbonate CC-600 (Jiangxi Guangyuan Chemical Co., Ltd.) 260g, and flame retardant 8g.

[0062] Sample preparation: Accurately weigh each ingredient according to the formula and place them in a high-speed mixer to mix thoroughly. Add the mixed raw materials to a 170℃ open mill and start milling, with the milling time controlled within 10 minutes; After the initial refining, the material is placed in a 170℃ flat vulcanizing press and pressed into a 3-4mm thick sample. The pressing time is 3 minutes and the cooling time is 30 seconds. Cut the template into strips that meet the testing standards and set aside.

[0063] Test method: Vertical flammability: The vertical flammability rating was determined by using the UL94 plastic vertical and horizontal flammability tester from Yangzhou Changzhe Test Machinery Co., Ltd., in accordance with GB / T2408-2021 "Determination of flammability of plastics - Horizontal and Vertical Methods". Oxygen Index: The JF-5 fully automatic oxygen index tester from Chengde Jinjian Testing Co., Ltd. was used to test the flame retardancy of the material according to GB / T2406.2-2009 "Determination of Combustion Behavior by Oxygen Index Method for Plastics - Part 2: Room Temperature Test".

[0064] Test results: The flame retardant performance test results of the flame retardants prepared in Examples 1-6 and Comparative Examples 1-4 of this invention after being applied to flexible PVC materials are shown in Table 1 below: Table 1 Test Results

[0065] Results analysis: Oxygen index: The oxygen indices of Examples 1-6 were all between 26.3 and 27.2, which were significantly higher than those of Comparative Examples 1-4 (24.5-25.8), indicating that the composite flame retardant of the present invention can significantly improve the flame retardancy of soft PVC materials and the flame retardant efficiency is significantly better than that of the comparative samples; among them, the oxygen index of Example 5 reached 27.2, which was the highest among all samples, and the flame retardant effect was the best.

[0066] Combustion time: t1+t2, t in Examples 1-6 t Both t2 and t3 are much shorter than those in comparative examples 1-4, indicating that the composite flame retardant of the present invention can effectively shorten the burning time of PVC materials, quickly extinguish flames, and reduce the continuous harm of fire.

[0067] Molten droplets and cotton pad ignition: None of the examples ignited the cotton pads, while all comparative examples ignited the cotton pads, indicating that the composite flame retardant of the present invention can effectively reduce the phenomenon of molten droplets during combustion, significantly reduce the risk of fire spread, and improve safety in use.

[0068] Vertical flammability rating: All embodiments achieved UL94V1 rating, while all comparative examples only achieved V2 rating, indicating that the flame retardant performance of the composite flame retardant of the present invention is far superior to that of the comparative samples, and fully meets the flame retardant safety requirements of PVC artificial leather in various application fields.

[0069] Influence of key component parameters: Comparative Examples 1-3 are samples with larger magnesium hydroxide particle size, and Comparative Example 4 is a sample with larger talc particle size. Their flame retardant properties have decreased significantly, proving that limiting the particle size parameters of heat-resistant inorganic fillers and nucleating agents in this invention is the key to achieving excellent flame retardant effects. Example 5 is a combination of magnesium hydroxide (GY-6000) with the preferred particle size and an appropriate amount of silane coupling agent. Its combustion indicators are optimal, verifying the rationality of the formulation parameter optimization.

[0070] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A halogen-antimony synergistic low-smoke heat-resistant composite flame retardant, characterized in that, It is prepared from raw materials comprising the following parts by weight: Antimony trioxide 15-25 parts, chlorinated paraffin 30-40 parts, smoke suppressant 8-12 parts, nucleating agent 2-5 parts, heat-resistant inorganic filler 20-30 parts, surface modifier 1-3 parts; The smoke suppressant is a complex of zinc borate and zinc molybdate.

2. The halogen-antimony synergistic low-smoke heat-resistant composite flame retardant according to claim 1, characterized in that, The weight ratio of zinc borate to zinc molybdate is 1:1 to 2:

1.

3. The halogen-antimony synergistic low-smoke heat-resistant composite flame retardant according to claim 1 or 2, characterized in that, The nucleating agent is talc powder, and the talc powder has a silica content of ≥50% and a particle size D50 of 4~6μm.

4. The halogen-antimony synergistic low-smoke heat-resistant composite flame retardant according to claim 3, characterized in that, The heat-resistant inorganic filler is ultrafine magnesium hydroxide prepared by physical grinding of brucite as the raw ore, with a particle size D50 of 1.2μm~3.5μm; the surface modifier is a silane coupling agent.

5. The halogen-antimony synergistic low-smoke heat-resistant composite flame retardant according to claim 1, 2, or 4, characterized in that, The purity of the antimony trioxide is ≥99.8%; the chlorine content of the chlorinated paraffin is ≥70%, and the viscosity of the chlorinated paraffin at 25°C is 150~250 mPa·s.

6. The preparation method of the halogen-antimony synergistic low-smoke heat-resistant composite flame retardant according to any one of claims 1 to 5, characterized in that, Includes the following steps: 1) After mixing antimony trioxide, smoke suppressant, nucleating agent and heat-resistant inorganic filler, the mixture is heated, and then a surface modifier is added and mixed to activate the powder surface. 2) After cooling the activated powder, add chlorinated paraffin and mix evenly to obtain a halogen-antimony synergistic low-smoke heat-resistant composite flame retardant.

7. The preparation method according to claim 6, characterized in that, In step 1), the heating temperature is 90~110℃, the mixing speed after adding the surface modifier is 800~1200r / min, and the mixing time is 10~30min.

8. The preparation method according to claim 7, characterized in that, In step 2), the cooling temperature is 60~80℃, the mixing speed of chlorinated paraffin is 400~600r / min, and the mixing time is 6~20min.

9. The application of the halogen-antimony synergistic low-smoke heat-resistant composite flame retardant according to any one of claims 1 to 5 in the flame retardant modification of soft PVC artificial leather.

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