A silicon-based composite powder, a preparation method and application thereof, a polypropylene drawing composite material, and a preparation method thereof

Abstract

The present invention belongs to the technical field of plastic filling modification, and provides a silicon-based composite powder and its preparation method and application, as well as a polypropylene drawing composite material and its preparation method. In this method, a silica slurry with low solid content is added to a calcium hydroxide slurry to form a composite slurry, and then carbon dioxide is introduced into the composite slurry for reaction. Finally, a composite powder with lightweight nano-calcium carbonate coated on silica is prepared, and the composite powder is further modified with a coupling agent. The small-sized silica has strong reinforcing properties, can significantly improve the mechanical properties of the powder and promote the carbonization of nano-calcium. The present invention also provides a polypropylene drawing composite material, which is processed from the silicon-based composite powder, polypropylene, polyethylene resin, and additives through high-speed mixing and a twin-screw extruder into a polypropylene high-speed drawing composite material. The drawing and winding speed of the material can reach 372 m / min, and it has excellent reinforcing effects, solving the problem of poor mechanical properties of polypropylene drawing masterbatch.

Description

Technical Field

[0001] The present invention relates to the technical field of plastic filling and modification, and particularly relates to a silicon-based composite powder, a preparation method and application thereof, a polypropylene drawing composite material and a preparation method thereof. Background Art

[0002] Polypropylene is a plastic variety with the fastest development speed, and its output is second only to polyethylene and polyvinyl chloride. Polypropylene drawing masterbatch is the earliest and most used filling masterbatch in filling masterbatches, and is widely used in products such as bags, woven nets, and non-woven fabrics. Its addition amount is generally as high as 30-40%, and it has the advantages of improving the hand feeling, printability of plastic drawing products, facilitating degradation, reducing shrinkage rate, reducing production cost and improving production efficiency.

[0003] At present, the polypropylene drawing masterbatch uses ultrafine heavy calcium carbonate as a filler and polypropylene as a carrier. Since the particle size of ultrafine heavy calcium carbonate is generally above 2μm, its filling and reinforcing properties are not high. The winding speed of the masterbatch can only be 250m / min. At the same time, when applied to plastic drawing products, it is easy to affect the comprehensive mechanical properties of plastic drawing products (such as tensile strength, elongation at break, etc.), and it can only be applied to some low-end woven bag industries. How to improve the performance of polypropylene drawing masterbatch and apply it in a wider field has become an urgent problem for industry personnel to solve. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects in the prior art and provide a silicon-based composite powder, a preparation method and application thereof, a polypropylene drawing composite material and a preparation method thereof.

[0005] In order to achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a preparation method of a silicon-based composite powder, comprising the following steps:

[0007] (1) In a carbon dioxide atmosphere, calcium hydroxide slurry, silicon dioxide slurry and isopropyl alcohol are mixed for carbonization reaction to obtain a composite powder;

[0008] (2) The composite powder and a silane coupling agent are mixed to obtain the silicon-based composite powder.

[0009] Preferably, in step (1), the calcium hydroxide slurry is prepared from calcium oxide and water, and the mass ratio of calcium oxide to water is 4-6:1;

[0010] The solid content of the silicon dioxide slurry is 25-35%, and the particle size of silicon dioxide in the silicon dioxide slurry is 200-300nm;

[0011] The mass ratio of the calcium hydroxide slurry to the silicon dioxide slurry is 30 to 80:1;

[0012] The mass of the isopropanol is 5 to 15‰ of the mass of calcium oxide.

[0013] Preferably, the flow rate of the carbon dioxide in step (1) is 30 to 50 mL / min;

[0014] The temperature of the carbonization reaction is 25 to 60 °C, and the time is 1 to 3 h.

[0015] Preferably, the mass of the silane coupling agent in step (2) is 10 to 15‰ of the mass of the composite powder;

[0016] The rotation speed of the mixing in step (2) is 1200 to 2000 rpm, and the time is 10 to 15 min.

[0017] The present invention also provides a silicon-based composite powder obtained by the preparation method.

[0018] The present invention also provides an application of the silicon-based composite powder in a polypropylene drawing composite material.

[0019] The present invention also provides a polypropylene drawing composite material, which is prepared from raw materials comprising the following parts by mass:

[0020] 10 to 30 parts of polypropylene, 15 to 25 parts of linear low-density polyethylene, 5 to 15 parts of polyethylene wax, 3 to 6 parts of coupling agent, 1 to 5 parts of zinc stearate, 2 to 6 parts of stearic acid, and 200 to 300 parts of silicon-based composite powder.

[0021] The present invention also provides a preparation method of the polypropylene drawing composite material, comprising the following steps:

[0022] Mix the raw materials and then melt and extrude to obtain the polypropylene drawing composite material.

[0023] Preferably, the temperature of the mixing is 160 to 190 °C, the rotation speed is 2500 to 3000 rpm, and the time is 10 to 15 min.

[0024] Preferably, the temperature of the melt extrusion is 190 to 215 °C, and the rotation speed is 280 to 320 rpm.

[0025] The present invention provides a method for preparing a silicon-based composite powder. A silica slurry with a low solid content is added to a calcium hydroxide slurry to form a composite slurry, and then carbon dioxide is introduced into the composite slurry for reaction. Finally, a composite powder with light nano-calcium carbonate coated on silica is prepared, and the composite powder is then treated with a coupling agent. In the silicon-based composite powder of the present invention, silica is added. The small-sized silica has strong reinforcing properties and can significantly improve the mechanical properties of the powder. On the other hand, the addition of silica can promote the carbonization of nano-calcium, which is beneficial to the progress of the reaction. The present invention also provides a polypropylene drawing composite material. The silicon-based composite powder, polypropylene, polyethylene resin, and additives are processed by high-speed mixing and a twin-screw extruder into a polypropylene high-speed drawing composite material. The drawing and winding speed of the material can reach 372 m / min, and it has excellent reinforcing effects. Detailed Embodiments

[0026] The present invention provides a method for preparing a silicon-based composite powder, comprising the following steps:

[0027] (1) In a carbon dioxide atmosphere, a calcium hydroxide slurry, a silica slurry, and isopropanol are mixed for a carbonization reaction to obtain a composite powder;

[0028] (2) The composite powder and a silane coupling agent are mixed to obtain the silicon-based composite powder.

[0029] In the present invention, in step (1), the calcium hydroxide slurry is prepared from calcium oxide and water. The calcium oxide can be obtained by purchasing on the market or prepared. To avoid the situation of incomplete calcination of the calcium oxide purchased on the market, the present invention provides a method for preparing calcium oxide.

[0030] A method for preparing calcium oxide, comprising the following steps:

[0031] Limestone and anthracite are alternately stacked and calcined to obtain calcium oxide.

[0032] In the present invention, the particle size of the limestone is preferably 80 - 120 mm, more preferably 90 - 110 mm, and even more preferably 95 - 105 mm; the particle size of the anthracite is preferably 20 - 40 mm, more preferably 25 - 35 mm, and even more preferably 28 - 32 mm.

[0033] In the present invention, the mass ratio of the limestone to the anthracite is preferably 10:1 - 3, more preferably 10:1.5 - 2.5, and even more preferably 10:1.8 - 2.2.

[0034] In the present invention, the calcination temperature is preferably 800 - 950 °C, more preferably 850 - 900 °C, and still more preferably 860 - 880 °C; the time is preferably 10 - 50 min, more preferably 20 - 40 min, and still more preferably 25 - 30 min.

[0035] In the present invention, the calcium hydroxide slurry in step (1) is prepared from calcium oxide and water, and the mass ratio of calcium oxide to water is preferably 4 - 6:1, more preferably 4.5 - 5.5:1, and still more preferably 4.8 - 5.2:1.

[0036] In the present invention, the temperature of the water is preferably 50 - 70 °C, more preferably 55 - 65 °C, and still more preferably 58 - 62 °C.

[0037] In the present invention, the calcium hydroxide slurry is obtained by mixing calcium oxide and water, allowing it to stand, and then stirring.

[0038] In the present invention, the standing time is preferably 1 - 2 h, more preferably 1.2 - 1.8 h, and still more preferably 1.4 - 1.6 h.

[0039] In the present invention, the stirring speed is preferably 60 - 80 rpm, more preferably 65 - 75 rpm, and still more preferably 68 - 72 rpm; the time is preferably 30 - 50 min, more preferably 35 - 45 min, and still more preferably 38 - 42 min.

[0040] In the present invention, the solid content of the silica slurry is preferably 25 - 35%, more preferably 26 - 34%, and still more preferably 28 - 32%; the particle size of silica in the silica slurry is preferably 200 - 300 nm, more preferably 220 - 280 nm, and still more preferably 240 - 260 nm.

[0041] In the present invention, the mass ratio of the calcium hydroxide slurry to the silica slurry is preferably 30 - 80:1, more preferably 40 - 70:1, and still more preferably 50 - 60:1.

[0042] In the present invention, the mass of isopropanol is preferably 5 - 15‰ of the mass of calcium oxide, more preferably 6 - 14‰, and still more preferably 8 - 12‰.

[0043] In the present invention, the flow rate of carbon dioxide in step (1) is preferably 30 - 50 mL / min, more preferably 35 - 45 mL / min, and still more preferably 38 - 42 mL / min.

[0044] In the present invention, the temperature of the carbonization reaction is preferably 25 to 60 °C, more preferably 30 to 55 °C, and even more preferably 40 to 50 °C; the time is preferably 1 to 3 h, more preferably 1.5 to 2.5 h, and even more preferably 1.8 to 2.2 h; the rotation speed is preferably 80 to 120 rpm, more preferably 90 to 110 rpm, and even more preferably 95 to 105 rpm.

[0045] In the present invention, after the carbonization reaction is completed, aging, filtration, washing, and drying are sequentially carried out to obtain the composite powder.

[0046] In the present invention, the temperature of the aging is preferably 20 to 30 °C, more preferably 22 to 28 °C, and even more preferably 24 to 26 °C; the time is preferably 30 to 60 min, more preferably 40 to 50 min, and even more preferably 44 to 46 min; the filtration, washing, and drying are carried out by methods well known to those skilled in the art.

[0047] In the present invention, the particle size of the composite powder is preferably 300 to 400 nm, more preferably 320 to 380 nm, and even more preferably 340 to 360 nm; the composite powder has a structure of light nano-calcium carbonate coated with silicon dioxide.

[0048] In the present invention, the silane coupling agent in step (2) is preferably one or more of γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, γ-divinyltriaminopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and γ-diethylaminomethyltriethoxysilane.

[0049] In the present invention, the mass of the silane coupling agent in step (2) is preferably 10 to 15 ‰ of the mass of the composite powder, more preferably 11 to 14 ‰, and even more preferably 12 to 13 ‰.

[0050] In the present invention, the rotation speed of the mixing in step (2) is preferably 1200 to 2000 rpm, more preferably 1400 to 1800 rpm, and even more preferably 1500 to 1700 rpm; the time is preferably 10 to 15 min, more preferably 11 to 14 min, and even more preferably 12 to 13 min.

[0051] In the present invention, after mixing, the silane coupling agent is uniformly coated on the surface of the composite powder particles to obtain a silicon-based composite powder.

[0052] The present invention also provides a silicon-based composite powder obtained by the preparation method.

[0053] The present invention also provides the application of the silicon-based composite powder in a polypropylene drawing composite material.

[0054] The present invention also provides a polypropylene drawing composite material, which is prepared from raw materials comprising the following parts by mass:

[0055] 10 - 30 parts of polypropylene, 15 - 25 parts of linear low density polyethylene, 5 - 15 parts of polyethylene wax, 3 - 6 parts of coupling agent, 1 - 5 parts of zinc stearate, 2 - 6 parts of stearic acid, and 200 - 300 parts of silicon-based composite powder.

[0056] In the present invention, the parts by mass of the polypropylene are preferably 12 - 28 parts, more preferably 14 - 26 parts, and still more preferably 18 - 22 parts.

[0057] In the present invention, the type of the polypropylene is T30S.

[0058] In the present invention, the parts by mass of the linear low density polyethylene are preferably 16 - 24 parts, more preferably 17 - 23 parts, and still more preferably 18 - 22 parts.

[0059] In the present invention, the type of the linear low density polyethylene is 7042.

[0060] In the present invention, the parts by mass of the polyethylene wax are preferably 6 - 14 parts, more preferably 8 - 12 parts, and still more preferably 9 - 11 parts.

[0061] In the present invention, the parts by mass of the coupling agent are preferably 3.5 - 5.5 parts, more preferably 4 - 5 parts, and still more preferably 4.4 - 4.6 parts.

[0062] In the present invention, the coupling agent is preferably one or more of aluminate coupling agent, silane coupling agent, and titanate coupling agent.

[0063] In the present invention, the parts by mass of the zinc stearate are preferably 1.5 - 4.5 parts, more preferably 2 - 4 parts, and still more preferably 2.5 - 3.5 parts.

[0064] In the present invention, the parts by mass of the stearic acid are preferably 2.5 - 5.5 parts, more preferably 3 - 5 parts, and still more preferably 3.5 - 4.5 parts.

[0065] In the present invention, the parts by mass of the silicon-based composite powder are preferably 220 - 280 parts, more preferably 230 - 270 parts, and still more preferably 240 - 260 parts.

[0066] The present invention also provides a preparation method of the polypropylene drawing composite material, comprising the following steps:

[0067] Mix the raw materials and then melt and extrude to obtain the polypropylene drawing composite material.

[0068] In the present invention, the mixing is to preliminarily mix the silicon-based composite powder, coupling agent and stearic acid, and then add the remaining raw materials for mixing.

[0069] In the present invention, the rotation speed of the preliminary mixing is preferably 2500 - 3000 rpm, more preferably 2600 - 2900 rpm, and still more preferably 2700 - 2800 rpm; the time is preferably 3 - 5 min, more preferably 3.5 - 4.5 min, and still more preferably 3.8 - 4.2 min.

[0070] In the present invention, the temperature of the mixing is preferably 160 - 190 °C, more preferably 165 - 185 °C, and still more preferably 170 - 180 °C; the rotation speed is preferably 2500 - 3000 rpm, more preferably 2600 - 2900 rpm, and still more preferably 2700 - 2800 rpm; the time is preferably 10 - 15 min, more preferably 11 - 14 min, and still more preferably 12 - 13 min.

[0071] In the present invention, the temperature of the melt extrusion is preferably 190 - 215 °C, more preferably 195 - 210 °C, and still more preferably 200 - 205 °C; the rotation speed is preferably 280 - 320 rpm, more preferably 290 - 310 rpm, and still more preferably 295 - 305 rpm.

[0072] In the present invention, the temperature of the melt extrusion can be represented by the zone temperature, and the melt extrusion is carried out by a twin-screw extruder; the temperature of the first zone of the twin-screw extruder is preferably 185 - 195 °C, more preferably 186 - 194 °C, and still more preferably 187 - 193 °C; the temperature of the second zone is preferably 185 - 195 °C, more preferably 186 - 194 °C, and still more preferably 187 - 193 °C; the temperature of the third zone is preferably 190 - 200 °C, more preferably 192 - 198 °C, and still more preferably 194 - 196 °C; the temperature of the fourth zone is preferably 195 - 205 °C, more preferably 196 - 204 °C, and still more preferably 198 - 202 °C; the temperature of the fifth zone is preferably 195 - 205 °C, more preferably 196 - 204 °C, and still more preferably 198 - 202 °C; the temperature of the sixth zone is preferably 200 - 210 °C, more preferably 202 - 208 °C, and still more preferably 204 - 206 °C; the temperature of the seventh zone is preferably 200 - 210 °C, more preferably 202 - 208 °C, and still more preferably 204 - 206 °C; the temperature of the eighth zone is preferably 205 - 215 °C, more preferably 206 - 214 °C, and still more preferably 208 - 212 °C; the temperature of the ninth zone is preferably 205 - 215 °C, more preferably 206 - 214 °C, and still more preferably 208 - 212 °C; the temperature of the die head is preferably 205 - 215 °C, more preferably 206 - 214 °C, and still more preferably 208 - 212 °C.

[0073] In the present invention, the feeding speed of melt extrusion is preferably 25 - 30 rpm, more preferably 26 - 29 rpm, and still more preferably 27 - 28 rpm.

[0074] In the present invention, the polypropylene drawing composite material is obtained by air cooling and pelletizing after melt extrusion.

[0075] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0076] Example 1

[0077] Place 100 mm of limestone and 30 mm of anthracite in a layer-by-layer manner of one layer of limestone and one layer of anthracite. The mass ratio of limestone to anthracite is 10:1. Calcinate the limestone in the kiln at 900 °C for 40 min to obtain quicklime. Add the obtained quicklime to a hot water pool at 60 °C. The mass ratio of quicklime to water is 4:1. After standing for 2 h, stir at 70 rpm for 40 min to obtain a calcium hydroxide slurry; then add a silica slurry with a solid content of 30% to the calcium hydroxide slurry (the mass ratio of the calcium hydroxide slurry to the silica slurry is 60:1, and the particle size of silica is 240 nm), then add isopropyl alcohol accounting for 5‰ of the mass of quicklime, and introduce carbon dioxide at 40 mL / min. Carry out a carbonization reaction at 40 °C and 100 rpm for 2 h, then age at 25 °C for 40 min, and obtain a composite powder after filtration, washing and drying. Add γ-aminopropylmethyldimethoxysilane accounting for 10‰ of the mass of the powder to the composite powder, and carry out surface modification treatment by stirring at 1500 rpm for 15 min to obtain a silicon-based composite powder.

[0078] Stir 240 parts of the silicon-based composite powder, 5 parts of silane coupling agent and 5 parts of stearic acid at 2800 rpm for 3 min, then add 25 parts of polypropylene T30S, 20 parts of linear low density polyethylene 7042, 4 parts of zinc stearate, 12 parts of polyethylene wax, then raise the temperature to 180 °C, stir at 2500 rpm for 12 min, discharge and cool to room temperature, then add it to a twin-screw extruder, control the temperature at 210 °C and the rotation speed at 300 rpm for extrusion. The temperature of the first zone is 190 °C, the second zone is 190 °C, the third zone is 195 °C, the fourth zone is 200 °C, the fifth zone is 200 °C, the sixth zone is 205 °C, the seventh zone is 205 °C, the eighth zone is 210 °C, the ninth zone is 210 °C, the head temperature is 210 °C, the feeding speed is 28 rpm, and the polypropylene drawing composite material is obtained by air cooling and pelletizing after extrusion.

[0079] Example 2

[0080] Place 110 mm of limestone and 20 mm of anthracite in a layer-by-layer manner of one layer of limestone and one layer of anthracite. The mass ratio of limestone to anthracite is 10:2. Calcinate the limestone in the kiln at 850 °C for 30 min to obtain quicklime. Add the obtained quicklime to a hot water pool at 50 °C. The mass ratio of quicklime to water is 5:1. After standing for 1.5 h, stir at 80 rpm for 50 min to obtain a calcium hydroxide slurry; then add a silica slurry with a solid content of 25% (the mass ratio of the calcium hydroxide slurry to the silica slurry is 40:1, and the particle size of silica is 300 nm) to the calcium hydroxide slurry, then add isopropanol accounting for 10‰ of the mass of quicklime, and introduce carbon dioxide at 35 mL / min. Carry out a carbonization reaction at 50 °C and 120 rpm for 2.5 h, then age at 25 °C for 60 min, and obtain a composite powder through filtration, washing, and drying. Add γ-aminopropylmethyldiethoxysilane accounting for 13‰ of the powder mass to the composite powder, and carry out surface modification treatment by stirring at 2000 rpm for 10 min to obtain a silicon-based composite powder.

[0081] Stir 230 parts of the silicon-based composite powder, 6 parts of the silane coupling agent, and 2 parts of stearic acid at 2600 rpm for 5 min, then add 13 parts of polypropylene T30S, 23 parts of linear low-density polyethylene 7042, 2 parts of zinc stearate, and 11 parts of polyethylene wax, then raise the temperature to 165 °C, stir at 2700 rpm for 15 min, discharge and cool to room temperature, then add it to a twin-screw extruder, control the temperature at 215 °C, and the rotation speed at 310 rpm for extrusion. Among them, the temperature of the first zone is 190 °C, the temperature of the second zone is 190 °C, the temperature of the third zone is 195 °C, the temperature of the fourth zone is 200 °C, the temperature of the fifth zone is 200 °C, the temperature of the sixth zone is 205 °C, the temperature of the seventh zone is 205 °C, the temperature of the eighth zone is 210 °C, the temperature of the ninth zone is 210 °C, the temperature of the die head is 210 °C, and the feeding speed is 30 rpm. After extrusion, cool with air and pelletize to obtain a polypropylene drawing composite material.

[0082] Example 3

[0083] Place 90 mm of limestone and 40 mm of anthracite in a layer-by-layer manner, with a mass ratio of limestone to anthracite of 10:3. Calcinate the limestone in the kiln at 950 °C for 40 min to obtain quicklime. Add the obtained quicklime to a hot water bath at 70 °C, with a mass ratio of quicklime to water of 6:1. Let it stand for 2 h and then stir at 60 rpm for 40 min to obtain a calcium hydroxide slurry. Then add a silica slurry with a solid content of 32% (the mass ratio of the calcium hydroxide slurry to the silica slurry is 75:1, and the particle size of silica is 210 nm) to the calcium hydroxide slurry, then add isopropyl alcohol at 15‰ of the mass of the quicklime, and pass carbon dioxide at 48 mL / min. Carry out a carbonization reaction at 30 °C and 85 rpm for 1 h, then age at 25 °C for 40 min, and obtain a composite powder after filtration, washing, and drying. Add γ-divinyltriaminopropyltrimethoxysilane at 15‰ of the powder mass to the composite powder, and stir at 1300 rpm for 11 min for surface modification treatment to obtain a silicon-based composite powder.

[0084] Stir 300 parts of the silicon-based composite powder, 3 parts of titanate coupling agent, and 6 parts of stearic acid at 3000 rpm for 5 min, then add 27 parts of polypropylene T30S, 18 parts of linear low-density polyethylene 7042, 5 parts of zinc stearate, and 15 parts of polyethylene wax. Then heat up to 190 °C and stir at 3000 rpm for 15 min, discharge and cool to room temperature, then add it to a twin-screw extruder, control the temperature at 215 °C, and the rotation speed at 280 rpm for extrusion. Among them, the temperature of zone 1 is 185 °C, the temperature of zone 2 is 185 °C, the temperature of zone 3 is 190 °C, the temperature of zone 4 is 195 °C, the temperature of zone 5 is 195 °C, the temperature of zone 6 is 205 °C, the temperature of zone 7 is 200 °C, the temperature of zone 8 is 205 °C, the temperature of zone 9 is 205 °C, the temperature of the die head is 210 °C, and the feeding speed is 25 rpm. After extrusion, it is air-cooled and pelletized to obtain a polypropylene drawing composite material.

[0085] Comparative example

[0086] The ultrafine calcium carbonate (particle size of 2.2 μm) was surface-modified by adding a silane coupling agent at 15‰ of the powder mass, and then 240 parts of ultrafine calcium carbonate powder, 5 parts of silane coupling agent, and 5 parts of stearic acid were stirred at 2800 rpm for 3 min. Then, 25 parts of polypropylene T30S, 20 parts of linear low-density polyethylene 7042, 4 parts of zinc stearate, and 12 parts of polyethylene wax were added in sequence, and the temperature was raised to 180 °C. After stirring at 2500 rpm for 12 min, the mixture was discharged and cooled to room temperature. Finally, the mixture was extruded through a twin-screw extruder at a temperature of 210 °C and 300 rpm, air-cooled, and pelletized to obtain a polypropylene high-speed drawing masterbatch product. The temperature range of the twin-screw extruder was as follows: zone 1 at 190 °C, zone 2 at 190 °C, zone 3 at 195 °C, zone 4 at 200 °C, zone 5 at 200 °C, zone 6 at 205 °C, zone 7 at 205 °C, zone 8 at 210 °C, zone 9 at 210 °C, and the die head at 210 °C. The feeding speed was 28 rpm, and the extruder speed was 300 rpm.

[0087] The polypropylene high-speed drawing masterbatches prepared in Examples 1 to 3 and the comparative example above were processed into standard specimens and drawn on the machine according to the ratio of matrix resin (PP) to masterbatch of 2:1, and the performance was tested according to GB / T 1040.1-2018. The tested performance data are shown in Table 1.

[0088] Table 1 Test results of physical and mechanical property indexes of Examples 1 to 3 and the comparative example

[0089] Tensile strength MPa Elongation at break % Drawing speed m / min Example 1 45.1 202.5 361 Example 2 45.4 204.8 367 Example 3 45.8 206.4 372 Comparative example 36.7 147.4 277

[0090] As can be seen from the above examples, the present invention provides a method for preparing a silicon-based composite powder. A silica slurry with a low solid content is added to a calcium hydroxide slurry to form a composite slurry, and then carbon dioxide is introduced into the composite slurry for reaction. Finally, a composite powder of light nano-calcium carbonate coated with silica is prepared, and the composite powder is further modified with a coupling agent. In the silicon-based composite powder of the present invention, silica is added. The small-particle-size silica has strong reinforcing properties and can significantly improve the mechanical properties of the powder. On the other hand, the addition of silica can promote the carbonization of nano-calcium, which is beneficial to the progress of the reaction. The present invention also provides a polypropylene drawing composite material. The silicon-based composite powder, polypropylene, polyethylene resin, and additives are processed into a polypropylene high-speed drawing composite material through high-speed mixing and a twin-screw extruder. The drawing and winding speed of the material can reach 372 m / min, and it has excellent reinforcing effects.

[0091] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of 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 preparation method of a silicon-based composite powder, characterized in that, it comprises the following steps: (1) In a carbon dioxide atmosphere, a calcium hydroxide slurry, a silica slurry and isopropyl alcohol are mixed for a carbonization reaction to obtain a composite powder; (2) The composite powder and a silane coupling agent are mixed to obtain the silicon-based composite powder; In step (1), the calcium hydroxide slurry is prepared from calcium oxide and water, and the mass ratio of calcium oxide to water is 4 - 6:1; The mass of the isopropyl alcohol is 5 - 15‰ of the mass of calcium oxide; In step (1), the flow rate of the carbon dioxide is 30 - 50 mL / min; The temperature of the carbonization reaction is 25 - 60 °C, and the time is 1 - 3 h.

2. The preparation method according to claim 1, characterized in that, in step (1), the solid content of the silica slurry is 25 - 35%, and the particle size of the silica in the silica slurry is 200 - 300 nm; The mass ratio of the calcium hydroxide slurry to the silica slurry is 30 - 80:

1.

3. The preparation method according to claim 2, characterized in that, in step (2), the mass of the silane coupling agent is 10 - 15‰ of the mass of the composite powder; In step (2), the rotation speed of the mixing is 1200 - 2000 rpm, and the time is 10 - 15 min.

4. The silicon-based composite powder obtained by the preparation method according to any one of claims 1 - 3.

5. The application of the silicon-based composite powder according to claim 4 in a polypropylene drawing composite material.

6. A polypropylene drawing composite material, characterized in that, it is prepared from raw materials comprising the following parts by mass: 10 - 30 parts of polypropylene, 15 - 25 parts of linear low-density polyethylene, 5 - 15 parts of polyethylene wax, 3 - 6 parts of coupling agent, 1 - 5 parts of zinc stearate, 2 - 6 parts of stearic acid, 200 - 300 parts of the silicon-based composite powder according to claim 4.

7. The preparation method of the polypropylene drawing composite material according to claim 6, characterized in that, it comprises the following steps: The raw materials are mixed and then melt-extruded to obtain the polypropylene drawing composite material.

8. The preparation method according to claim 7, characterized in that, the temperature of the mixing is 160 - 190 °C, the rotation speed is 2500 - 3000 rpm, and the time is 10 - 15 min.

9. The preparation method according to claim 7 or 8, characterized in that, the temperature of the melt-extrusion is 190 - 215 °C, and the rotation speed is 280 - 320 rpm.