Foaming master batch and preparation method thereof

Abstract

The invention relates to a foaming master batch and a preparation method thereof, and belongs to the technical field of polymer foaming materials. According to the invention, hyperbranched polyester polyol is adopted to graft maleic anhydride to modify polyethylene, the branching degree of polyethylene is improved, a polyhydroxy structure is introduced, and then the modified branched polyhydroxy polyethylene is fused and mixed with isocyanate-based modified nano calcium carbonate and isocyanate-based modified talcum powder; the nano calcium carbonate and the talcum powder are chemically bonded through isocyanate groups and hydroxyl groups in polyethylene chain segments, the polyethylene chain segments grafted on the surfaces of the nano calcium carbonate and the talcum powder can effectively improve the compatibility of the filler and a polyethylene matrix, and the hyperbranched polyester structure can improve the lubricity of the filler. And the branched chain segment can increase the steric hindrance of the filler, avoid the agglomeration of the filler and further increase the dispersion uniformity of the filler, and the uniformly dispersed filler can effectively improve the surface gloss, mechanical properties and thermal insulation properties of the foam material.

Description

A foaming masterbatch and its preparation method Technical Field

[0001] This invention relates to a foaming masterbatch and its preparation method, belonging to the field of polymer foaming material technology. Background Technology

[0002] Foamed plastics have high impact strength, specific strength, fatigue strength and thermal stability, as well as low electrical conductivity and thermal conductivity, and are widely used in packaging, construction, automotive industry, aerospace industry and sporting goods industry.

[0003] Using foaming masterbatch to prepare foamed plastic products solves problems such as dust and measurement errors, simplifies the production process, improves product quality, and achieves the goals of saving time and increasing efficiency. Foaming masterbatch is a processing aid used in the production of foamed products. It is made by mixing carrier resin, foaming agent, nucleating agent, dispersant, and foaming activator into a high-concentration dispersion, then kneading and extruding it into granules. It has high development and utilization value.

[0004] However, nucleating agents are inorganic particles with poor compatibility with polymer matrices such as polyethylene, resulting in poor dispersibility during processing. Unevenly dispersed nucleating agent particles can affect foaming uniformity, which in turn leads to deviations in the mechanical properties, surface quality, and thermal insulation performance of the foamed material. Summary of the Invention

[0005] The purpose of this invention is to provide a foaming masterbatch and its preparation method, so as to solve the problem that the uneven dispersion of inorganic nucleating agents in the preparation of polyethylene foaming masterbatch leads to deviations in the mechanical properties, surface quality and thermal insulation performance of the foamed material.

[0006] The preparation method of the foaming masterbatch of the present invention includes the following steps: (1) mixing maleic anhydride-grafted polyethylene and hyperbranched polyester polyol in a solvent at 60~70℃ to obtain hyperbranched polyester-grafted polyethylene; the ratio of the molar amount of hydroxyl groups of the hyperbranched polyester polyol to the molar amount of maleic anhydride of the maleic anhydride-grafted polyethylene is 2.5~3.5:1; (2) melting and extruding hyperbranched polyester-grafted polyethylene, isocyanate-modified nano-calcium carbonate and isocyanate-modified talc to obtain modified multifunctional filler; the sum of the molar amount of isocyanate groups of the isocyanate-modified nano-calcium carbonate and the molar amount of isocyanate groups of the isocyanate-modified talc is equal to the molar amount of hydroxyl groups of the hyperbranched polyester-grafted polyethylene; (3) melting and extruding polyethylene, foaming agent and modified multifunctional filler to obtain foaming masterbatch.

[0007] Preferably, the maleic anhydride-grafted polyethylene has a grafting rate of 0.9-1.3% and an average molecular weight of 80,000-100,000; the hyperbranched polyester polyol has a relative molecular weight of 1800-2000 and a hydroxyl functionality of 16.5-18.

[0008] Preferably, the mixing reaction time in step (1) is 1 to 2 hours.

[0009] Preferably, the preparation method of the isocyanate-modified nano-calcium carbonate is as follows: nano-calcium carbonate and 3-isocyanate-propyltrimethoxysilane in a mass ratio of 10:5~8 are heated in toluene to 100~110℃ and stirred for 12~15h to obtain isocyanate-modified nano-calcium carbonate.

[0010] Preferably, the average particle size of the nano-calcium carbonate is 30~50nm.

[0011] Preferably, the isocyanate-modified talc is prepared as follows: talc powder and 3-isocyanate-propyltrimethoxysilane in a mass ratio of 10:5~8 are heated in toluene to 100~110℃ and stirred for 12~15h to obtain isocyanate-modified talc.

[0012] Preferably, the average particle size of the talc powder is 2~5μm.

[0013] Preferably, in step (2), the temperature of melt extrusion is 185~195℃.

[0014] Preferably, in step (3), the melting temperature of polyethylene is 108~110℃, the foaming agent is azodicarbonamide, and the mass ratio of polyethylene, foaming agent and modified multifunctional filler is 60:35~45:10~15; the melt extrusion temperature is 150~160℃.

[0015] A foaming masterbatch prepared by the method described above.

[0016] The beneficial effects of the foaming masterbatch and its preparation method of the present invention are as follows: The present invention uses hyperbranched polyester polyol to graft maleic anhydride onto polyethylene to modify it, thereby increasing the branching degree of polyethylene and introducing a polyhydroxy structure. Then, the modified branched polyhydroxy polyethylene is melt-mixed with isocyanate-modified nano-calcium carbonate and isocyanate-modified talc powder, so that the nano-calcium carbonate and talc powder are chemically bonded through the isocyanate groups and the hydroxyl groups in the polyethylene chain segments. The polyethylene chain segments grafted on the surface of nano-calcium carbonate and talc powder can effectively improve the compatibility between the filler and the polyethylene matrix. The hyperbranched polyester structure can improve the lubricity of the filler and further improve its dispersibility in the system. The branched chain segments can increase the steric hindrance of the filler, avoid filler agglomeration, and further increase the uniformity of filler dispersion. The uniformly dispersed filler can effectively improve the surface gloss, mechanical properties and thermal insulation performance of the foamed material. Detailed Implementation

[0017] The following examples are intended to further illustrate the content of the present invention, but not to limit the scope of protection of the present invention. Example 1

[0018] The preparation method of the foaming masterbatch in this embodiment includes the following steps: (1) 10g of maleic anhydride-grafted polyethylene (the grafting rate of maleic anhydride-grafted polyethylene is 0.9%, and the average molecular weight is 80,000) and 110g of carbon tetrachloride are added to a glass bottle, heated to 60°C, and stirred until the maleic anhydride-grafted polyethylene is fully dissolved. Then, hyperbranched polyester polyol P500 (relative molecular weight 1800, acid value 0.56mg / g, hydroxyl functionality 16.5) is added, and the reaction is stirred for 1h. The reaction solution is then distilled under reduced pressure at 40°C to remove the solvent carbon tetrachloride, and hyperbranched polyester-grafted polyethylene is obtained. During the reaction, the ratio of the molar amount of hydroxyl in hyperbranched polyester polyol P500 to the molar amount of maleic anhydride in maleic anhydride-grafted polyethylene is controlled to be 2.5:1.

[0019] (2) 10g of nano calcium carbonate (average particle size of 30nm) was dried in a vacuum drying oven at 60℃ for 24 hours and then placed in a glass reaction flask. Nitrogen gas was then introduced into the glass reaction flask and 350mL of toluene was added. After the mixture was evenly dispersed, 5g of 3-isocyanate-propyltrimethoxysilane was added. The mixture was heated to 100℃ and stirred for 12 hours. After cooling to room temperature, the mixture was filtered. The filter cake was washed with toluene and ethanol and dried to obtain isocyanate-modified nano calcium carbonate.

[0020] (3) 10g of talc powder (average particle size of 2μm) was dried in a vacuum drying oven at 60℃ for 24 hours and then placed in a glass reaction flask. Nitrogen gas was then introduced into the glass reaction flask and 350mL of toluene was added. After the mixture was evenly dispersed, 5g of 3-isocyanate-propyltrimethoxysilane was added. The mixture was heated to 100℃ and stirred for 12 hours. After cooling to room temperature, the mixture was filtered. The filter cake was washed with toluene and ethanol and dried to obtain isocyanate-modified talc powder.

[0021] (4) After the hyperbranched polyester grafted polyethylene, isocyanate-modified nano calcium carbonate and isocyanate-modified talc are stirred evenly, they are placed in a twin-screw extruder and melt-extruded and granulated at 185°C to obtain the modified multifunctional filler; wherein, the mass ratio of isocyanate-modified nano calcium carbonate and isocyanate-modified talc is 2:7, and the sum of the isocyanate molar amount of isocyanate-modified nano calcium carbonate and the isocyanate molar amount of isocyanate-modified talc is equal to the hydroxyl molar amount of hyperbranched polyester grafted polyethylene.

[0022] (5) Low-density polyethylene (melt temperature 108℃), azodicarbonamide, and modified multifunctional filler were mixed evenly at a mass ratio of 60:35:10 and then added to a twin-screw extruder. The mixture was melt-extruded and granulated at 150℃ to obtain foaming masterbatch. Example 2

[0023] The preparation method of the foaming masterbatch in this embodiment includes the following steps: (1) 10g of maleic anhydride-grafted polyethylene (the grafting rate of maleic anhydride-grafted polyethylene is 1.1%, and the average molecular weight is 90,000) and 110~120g of carbon tetrachloride are added to a glass bottle, heated to 65°C, and stirred until the maleic anhydride-grafted polyethylene is fully dissolved. Then, hyperbranched polyester polyol P500 (relative molecular weight 1800, acid value 0.56mg / g, hydroxyl functionality 16.5) is added, and the reaction is stirred for 1.5h. The reaction solution is then distilled under reduced pressure at 40°C to remove the solvent carbon tetrachloride, and hyperbranched polyester-grafted polyethylene is obtained. During the reaction, the ratio of the molar amount of hydroxyl in hyperbranched polyester polyol P500 to the molar amount of maleic anhydride in maleic anhydride-grafted polyethylene is controlled to be 3:1.

[0024] (2) 10g of nano calcium carbonate (average particle size of 40nm) was dried in a vacuum drying oven at 60℃ for 24 hours and then placed in a glass reaction flask. Nitrogen gas was then introduced into the glass reaction flask and 350mL of toluene was added. After the mixture was evenly dispersed, 6g of 3-isocyanate-propyltrimethoxysilane was added. The mixture was heated to 105℃ and stirred for 13 hours. After cooling to room temperature, the mixture was filtered. The filter cake was washed with toluene and ethanol and dried to obtain isocyanate-modified nano calcium carbonate.

[0025] (3) 10g of talc powder (average particle size of 3μm) was dried in a vacuum drying oven at 60℃ for 24 hours and then placed in a glass reaction flask. Nitrogen gas was then introduced into the glass reaction flask and 350mL of toluene was added. After the mixture was evenly dispersed, 7g of 3-isocyanate-propyltrimethoxysilane was added. The mixture was heated to 105℃ and stirred for 14 hours. After cooling to room temperature, the mixture was filtered. The filter cake was washed with toluene and ethanol and dried to obtain isocyanate-modified talc powder.

[0026] (4) After the hyperbranched polyester grafted polyethylene, isocyanate-modified nano calcium carbonate and isocyanate-modified talc are mixed evenly, they are placed in a twin-screw extruder and melt-extruded and granulated at 190°C to obtain the modified multifunctional filler; wherein, the mass ratio of isocyanate-modified nano calcium carbonate and isocyanate-modified talc is 3:8, and the sum of the isocyanate molar amount of isocyanate-modified nano calcium carbonate and the isocyanate molar amount of isocyanate-modified talc is equal to the hydroxyl molar amount of hyperbranched polyester grafted polyethylene.

[0027] (5) Low-density polyethylene (melt temperature 109℃), azodicarbonamide, and modified multifunctional filler were mixed evenly at a mass ratio of 60:40:12 and then added to a twin-screw extruder. The mixture was melt-extruded and granulated at 155℃ to obtain foaming masterbatch. Example 3

[0028] The preparation method of the foaming masterbatch in this embodiment includes the following steps: (1) 10g of maleic anhydride-grafted polyethylene (the grafting rate of maleic anhydride-grafted polyethylene is 1.3%, and the average molecular weight is 100,000) and 120g of carbon tetrachloride are added to a glass bottle, heated to 70°C, and stirred until the maleic anhydride-grafted polyethylene is fully dissolved. Then, hyperbranched polyester polyol P500 (relative molecular weight 1800, acid value 0.56mg / g, hydroxyl functionality 16.5) is added, and the reaction is stirred for 2h. The reaction solution is then distilled under reduced pressure at 40°C to remove the solvent carbon tetrachloride, and hyperbranched polyester-grafted polyethylene is obtained. During the reaction, the ratio of the molar amount of hydroxyl in hyperbranched polyester polyol P500 to the molar amount of maleic anhydride in maleic anhydride-grafted polyethylene is controlled to be 3.5:1.

[0029] (2) 10g of nano calcium carbonate (average particle size of 50nm) was dried in a vacuum drying oven at 60℃ for 24 hours and then placed in a glass reaction flask. Nitrogen gas was then introduced into the glass reaction flask and 350mL of toluene was added. After the mixture was evenly dispersed, 8g of 3-isocyanate-propyltrimethoxysilane was added. The mixture was heated to 110℃ and stirred for 15 hours. After cooling to room temperature, the mixture was filtered. The filter cake was washed with toluene and ethanol and dried to obtain isocyanate-modified nano calcium carbonate.

[0030] (3) 10g of talc powder (average particle size of 5μm) was dried in a vacuum drying oven at 60℃ for 24 hours and then placed in a glass reaction flask. Nitrogen gas was then introduced into the glass reaction flask and 350mL of toluene was added. After the mixture was evenly dispersed, 8g of 3-isocyanate-propyltrimethoxysilane was added. The mixture was heated to 110℃ and stirred for 15 hours. After cooling to room temperature, the mixture was filtered. The filter cake was washed with toluene and ethanol and dried to obtain isocyanate-modified talc powder.

[0031] (4) After the hyperbranched polyester grafted polyethylene, isocyanate-modified nano calcium carbonate and isocyanate-modified talc are stirred evenly, they are placed in a twin-screw extruder and melt-extruded and granulated at 195°C to obtain the modified multifunctional filler; wherein, the mass ratio of isocyanate-modified nano calcium carbonate and isocyanate-modified talc is 4:9, and the sum of the isocyanate molar amount of isocyanate-modified nano calcium carbonate and the isocyanate molar amount of isocyanate-modified talc is equal to the hydroxyl molar amount of hyperbranched polyester grafted polyethylene.

[0032] (5) Low-density polyethylene (melting temperature 110℃), azodicarbonamide and modified multifunctional filler are mixed evenly in a mass ratio of 60:45:15 and then added to a twin-screw extruder. The mixture is melt-extruded and granulated at 160℃ to obtain foaming masterbatch.

[0033] The difference between the preparation method of the foaming masterbatch in Comparative Example 1 and the preparation method of the foaming masterbatch in Example 1 is that the modified multifunctional filler in step (5) of the preparation method of the foaming masterbatch in this comparative example is a mixture of nano-calcium carbonate and talc powder. The nano-calcium carbonate is the same as the nano-calcium carbonate in step (2) of Example 1, and the talc powder is the same as the talc powder in step (3) of Example 1. The mass ratio of nano-calcium carbonate to talc powder is 2:7.

[0034] The difference between the preparation method of the foaming masterbatch in Comparative Example 2 and the preparation method of the foaming masterbatch in Example 1 is that the modified multifunctional filler in step (5) of the preparation method of the foaming masterbatch in this comparative example is a mixture of maleic anhydride grafted polyethylene, nano calcium carbonate and talc. The maleic anhydride grafted polyethylene is the same as the maleic anhydride grafted polyethylene in step (1) of Example 1, the nano calcium carbonate is the same as the nano calcium carbonate in step (2) of Example 1, and the talc is the same as the talc in step (3) of Example 1. The mass ratio of nano calcium carbonate and talc is 2:7. The ratio of the mass of maleic anhydride grafted polyethylene to the sum of the masses of nano calcium carbonate and talc is equal to the ratio of the mass of hyperbranched polyester grafted polyethylene to the sum of the masses of isocyanate-modified nano calcium carbonate and isocyanate-modified talc in step (4) of Example 1.

[0035] The difference between the preparation method of the foaming masterbatch in Comparative Example 3 and the preparation method of the foaming masterbatch in Example 1 is that the preparation method of the modified multifunctional filler in step (5) of the preparation method of the foaming masterbatch in this comparative example is as follows: After the hyperbranched polyester grafted polyethylene and isocyanate-modified nano calcium carbonate are stirred evenly, they are placed in a twin-screw extruder and melt-extruded and granulated at 185°C to obtain the modified multifunctional filler; wherein, the molar amount of isocyanate group in the isocyanate-modified nano calcium carbonate is equal to the molar amount of hydroxyl group in the hyperbranched polyester grafted polyethylene.

[0036] The difference between the preparation method of the foaming masterbatch in Comparative Example 4 and the preparation method of the foaming masterbatch in Example 1 is that the preparation method of the modified multifunctional filler in step (5) of the preparation method of the foaming masterbatch in this comparative example is as follows: After the hyperbranched polyester grafted polyethylene and isocyanate-modified talc powder are stirred evenly, they are placed in a twin-screw extruder and melt-extruded and granulated at 185°C to obtain the modified multifunctional filler; wherein, the molar amount of isocyanate group in the isocyanate-modified talc powder is equal to the molar amount of hydroxyl group in the hyperbranched polyester grafted polyethylene.

[0037] Experimental Example: This experimental example is used to evaluate the comprehensive performance of the foaming masterbatches prepared in each embodiment and comparative example. The experimental method is as follows: The foaming masterbatch and polyethylene were stirred evenly at a mass ratio of 1:1, and then foamed samples were prepared using an injection molding machine. The surface quality, mechanical properties, and thermal conductivity of the foamed samples were then tested. Surface quality was characterized by the surface gloss of the samples. Tensile strength and elongation at break in the mechanical properties were tested according to standard GB / T1040-1992, and notched impact strength was tested according to standard GB / T 1043-1993. Thermal conductivity was obtained using a thermal conductivity meter. The surface quality, mechanical properties, and thermal conductivity of the foamed samples processed using the foaming masterbatches prepared in each embodiment and comparative example are shown in Table 1.

[0038] Table 1 Surface quality, mechanical properties and thermal conductivity of foamed samples

[0039] As shown in Table 1, the present invention uses hyperbranched polyester polyol to graft maleic anhydride onto polyethylene, thereby increasing the branching degree of polyethylene and introducing a polyhydroxy structure. The modified branched polyhydroxy polyethylene is then melt-mixed with isocyanate-modified nano-calcium carbonate and isocyanate-modified talc powder. This allows the nano-calcium carbonate and talc powder to chemically bond through the isocyanate groups and the hydroxyl groups in the polyethylene segments. The polyethylene segments grafted onto the surfaces of the nano-calcium carbonate and talc powder can effectively improve the compatibility between the filler and the polyethylene matrix. The hyperbranched polyester structure can improve the lubricity of the filler and further enhance its dispersibility in the system. The branched segments can increase the steric hindrance of the filler, preventing filler agglomeration and further increasing the uniformity of filler dispersion. The uniformly dispersed filler can effectively improve the surface gloss, mechanical properties, and thermal insulation performance of the foamed material.

Claims

1. A method for preparing foaming masterbatch, characterized in that, The process includes the following steps: (1) mixing maleic anhydride-grafted polyethylene and hyperbranched polyester polyol in a solvent at 60-70°C to obtain hyperbranched polyester-grafted polyethylene; the ratio of the molar amount of hydroxyl groups in the hyperbranched polyester polyol to the molar amount of maleic anhydride in the maleic anhydride-grafted polyethylene is 2.5-3.5:1; (2) melting and extruding the hyperbranched polyester-grafted polyethylene, isocyanate-modified nano-calcium carbonate, and isocyanate-modified talc to obtain a modified multifunctional filler; the sum of the molar amounts of isocyanate groups in the isocyanate-modified nano-calcium carbonate and the isocyanate groups in the isocyanate-modified talc is equal to the molar amount of hydroxyl groups in the hyperbranched polyester-grafted polyethylene; (3) melting and extruding the polyethylene, foaming agent, and modified multifunctional filler to obtain a foaming masterbatch.

2. The method for preparing foaming masterbatch as described in claim 1, characterized in that, The grafting rate of the maleic anhydride-grafted polyethylene is 0.9-1.3%, and the average molecular weight is 80,000-100,000; the relative molecular weight of the hyperbranched polyester polyol is 1800-2000, and the hydroxyl functionality is 16.5-18.

3. The method for preparing foaming masterbatch as described in claim 1 or 2, characterized in that, The mixing reaction in step (1) takes 1 to 2 hours.

4. The method for preparing foaming masterbatch as described in claim 1, characterized in that, The preparation method of the isocyanate-modified nano-calcium carbonate is as follows: nano-calcium carbonate and 3-isocyanate-propyltrimethoxysilane in a mass ratio of 10:5~8 are heated in toluene to 100~110℃ and stirred for 12~15h to obtain isocyanate-modified nano-calcium carbonate.

5. The method for preparing foaming masterbatch as described in claim 4, characterized in that, The average particle size of the nano-calcium carbonate is 30~50nm.

6. The method for preparing foaming masterbatch as described in claim 1, characterized in that, The method for preparing the isocyanate-modified talc is as follows: talc powder and 3-isocyanate-propyltrimethoxysilane in a mass ratio of 10:5~8 are heated in toluene to 100~110℃ and stirred for 12~15h to obtain isocyanate-modified talc.

7. The method for preparing foaming masterbatch as described in claim 6, characterized in that, The average particle size of the talc powder is 2~5μm.

8. The method for preparing foaming masterbatch according to any one of claims 1, 4-7, characterized in that, In step (2), the temperature of melt extrusion is 185~195℃.

9. The method for preparing foaming masterbatch as described in claim 1, characterized in that, In step (3), the melting temperature of polyethylene is 108~110℃, the foaming agent is azodicarbonamide, and the mass ratio of polyethylene, foaming agent and modified multifunctional filler is 60:35~45:10~15; the melt extrusion temperature is 150~160℃.

10. A foaming masterbatch prepared by the method described in any one of claims 1-9.

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