Low-shrinkage modified polypropylene material

Abstract

The invention belongs to the technical field of polymer production and processing, and particularly relates to a low-shrinkage-rate modified polypropylene material, modified tetrapod-like zinc oxide whiskers and metallocene linear high-density polyethylene are introduced into the formula, the modified tetrapod-like zinc oxide whiskers have a highly regular three-dimensional structure, and the metallocene linear high-density polyethylene has a high shrinkage rate. The four needle-shaped bodies extending from the center can be directly inserted into the polypropylene, compared with other whiskers, the polypropylene can be better reinforced and toughened, meanwhile, the shrinkage rate of the polypropylene can be reduced due to the addition of the whisker, and the dosage is smaller; the addition of the metallocene linear high density polyethylene can hinder the crystallization of polypropylene to a certain extent so as to reduce the shrinkage rate, the addition of the inorganic filler can also influence the crystallization property of polypropylene and reduce the shrinkage rate of polypropylene, and the molding shrinkage rate of polypropylene is greatly reduced by utilizing the synergistic effect of the metallocene linear high density polyethylene, the inorganic filler and the polypropylene.

Description

Technical Field The invention belongs to the technical field of polymer production and processing, and specifically relates to a low-shrinkage modified polypropylene material. Background Art Polypropylene is a semi-crystalline resin, and its molding shrinkage is generally 1.4-2.6%, which is much larger than amorphous materials such as acrylonitrile-butadiene-styrene terpolymer (ABS), polystyrene (PS), and polycarbonate (PC) (molding shrinkage is 0.4-0.8%). The molding shrinkage here is also called secondary shrinkage, which refers to the size difference between the injection molded product and the mold cavity after injection molding. The shrinkage control of polypropylene has a great influence on its application range. Shrinkage behavior often occurs during the injection molding, storage and use of the product, resulting in warping of the product, local internal stress and unstable product size. Therefore, reducing the shrinkage of PP has become an important research direction for improving the performance of PP. In view of this, the inventor hopes to provide a low shrinkage modified polypropylene material. Summary of the invention The purpose of the present invention is to overcome the above problems existing in the conventional technology and provide a low shrinkage modified polypropylene material. In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions: A low-shrinkage modified polypropylene material comprises the following raw materials in parts by weight: 40-80 parts of polypropylene copolymer, 10-20 parts of metallocene linear high-density polyethylene, 10-20 parts of inorganic filler, 2-5 parts of modified four-needle zinc oxide whiskers, 0.8-1.2 parts of beta crystal nucleating agent and 1-2 parts of antioxidant. Furthermore, the polypropylene copolymer is copolymer polypropylene K7726H, and the melt flow rate of copolymer polypropylene K7726H under the test conditions of 230° C.×2.16 kg is 26 g / 10 min. Furthermore, the density of the metallocene linear high-density polyethylene is 0.94 to 0.96 g / cm 3 , molecular weight is 80000~120000g / mol, and molecular weight distribution MWD is 2~3. Furthermore, the inorganic filler is one of talc, calcium carbonate and barium sulfate. Furthermore, the modified tetrapod-shaped zinc oxide whisker is a γ-aminopropyltriethoxysilane surface-modified tetrapod-shaped zinc oxide whisker, specifically, γ-aminopropyltriethoxysilane is dissolved in an organic solvent to obtain a γ-aminopropyltriethoxysilane solution, the tetrapod-shaped zinc oxide whisker is dispersed in the γ-aminopropyltriethoxysilane solution, and the solid is separated and collected to obtain the modified tetrapod-shaped zinc oxide whisker. Furthermore, the β-crystal nucleating agent is one of calcium stearate / pimelic acid complex, calcium pimelate, and rare earth β-nucleating agent. Furthermore, the antioxidant is antioxidant 1010 or antioxidant 168. Furthermore, the preparation method thereof comprises the following steps: 1) First, put 40-80 parts of polypropylene copolymer, 10-20 parts of metallocene linear high-density polyethylene, and 10-20 parts of inorganic filler into a high-speed mixer, and mix them at 80-90° C. for 10-20 minutes; 2) Add 2-5 parts of modified tetrapod-shaped zinc oxide whiskers, 0.8-1.2 parts of β-crystal nucleating agent, and 1-2 parts of antioxidant; continue mixing for 6-10 minutes; 3) The mixed material is added into a twin-screw extruder with each zone temperature of 190-210° C. for extrusion granulation to obtain a modified polypropylene material. The beneficial effects of the present invention are: The invention introduces modified four-needle zinc oxide whisker and metallocene linear high-density polyethylene into the formula, wherein the modified four-needle zinc oxide whisker has a highly regular three-dimensional structure, and four needle-shaped bodies extending from the center thereof can be directly inserted into the polypropylene, and can better strengthen and toughen the polypropylene than other whiskers, and its addition can also reduce the shrinkage rate of the polypropylene, and the amount used is less; the addition of the metallocene linear high-density polyethylene can hinder the crystallization of the polypropylene to a certain extent, and thereby reduce the shrinkage rate, and the addition of the inorganic filler can also affect the crystallization performance of the polypropylene, and reduce the shrinkage rate of the polypropylene, and the invention utilizes the synergistic effect of the above three, and greatly reduces the molding shrinkage rate of the polypropylene.

[0019] Crystallization is one of the main reasons for the shrinkage of polypropylene, so choosing the right grade of polypropylene raw material is also very important. Importantly, the present invention uses copolymer polypropylene K9026 produced by Yanshan Petrochemical, which has a melting point of 230°C x 2.16kg under the test conditions. The volume flow rate is 30g / 10min. The combination of this raw material and other components can better solve the shrinkage problem of polypropylene materials. The invention reduces the shrinkage rate of polypropylene material by introducing metallocene linear high-density polyethylene, which is basically close to the shrinkage rate of polystyrene, and the mechanical properties such as tensile strength, bending strength, and cantilever beam notched impact strength are higher than those of polystyrene, and has good flame retardant effect. The cost of polypropylene material is lower than the production cost of polystyrene, so it can replace polystyrene material for injection molding of parts, and has broad market application prospects. Of course, any product implementing the present invention does not necessarily need to achieve all of the above advantages at the same time. DETAILED DESCRIPTION The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. The relevant specific embodiments of the present invention are as follows: Example 1 A low-shrinkage modified polypropylene material comprises the following raw materials in parts by weight: 40 parts of polypropylene copolymer, 20 parts of metallocene linear high-density polyethylene, 10 parts of inorganic filler, 5 parts of modified four-needle zinc oxide whiskers, 0.8 parts of beta crystal nucleating agent, and 2 parts of antioxidant. In this embodiment, the polypropylene copolymer is copolymerized polypropylene K7726H, and the melt flow rate of copolymerized polypropylene K7726H under the test conditions of 230° C.×2.16 kg is 26 g / 10 min. In this embodiment, the density of the metallocene linear high-density polyethylene is 0.94-0.96 g / cm 3 , molecular weight is 80000~120000g / mol, and molecular weight distribution MWD is 2~3. In this embodiment, the inorganic filler is talcum powder. In the present embodiment, the modified tetrapod-shaped zinc oxide whiskers are γ-aminopropyltriethoxysilane surface-modified tetrapod-shaped zinc oxide whiskers. Specifically, γ-aminopropyltriethoxysilane is dissolved in an organic solvent to obtain a γ-aminopropyltriethoxysilane solution, the tetrapod-shaped zinc oxide whiskers are dispersed in the γ-aminopropyltriethoxysilane solution, and the solid is separated and collected to obtain the modified tetrapod-shaped zinc oxide whiskers. In this embodiment, the β-crystal nucleating agent is a calcium stearate / pimelic acid complex. In this embodiment, the antioxidant is antioxidant 1010. In this embodiment, the preparation method of the low shrinkage modified polypropylene material comprises the following steps: 1) First, put the polypropylene copolymer, metallocene linear high-density polyethylene and inorganic filler into a high-speed mixer and mix them at 85°C for 15 minutes; 2) Add modified tetrapod-shaped zinc oxide whiskers, β-crystal nucleating agent, and antioxidant; continue mixing for 8 minutes; 3) The mixed material is added into a twin-screw extruder with a temperature of 200° C. in each zone for extrusion granulation to obtain a modified polypropylene material. Example 2 A low-shrinkage modified polypropylene material comprises the following raw materials in parts by weight: 50 parts of polypropylene copolymer, 18 parts of metallocene linear high-density polyethylene, 12 parts of inorganic filler, 4 parts of modified four-needle zinc oxide whisker, 1.1 parts of beta crystal nucleating agent and 2 parts of antioxidant. In this embodiment, the polypropylene copolymer is copolymerized polypropylene K7726H, and the melt flow rate of copolymerized polypropylene K7726H under the test conditions of 230° C.×2.16 kg is 26 g / 10 min. In this embodiment, the density of the metallocene linear high-density polyethylene is 0.94-0.96 g / cm 3 , molecular weight is 80000~120000g / mol, and molecular weight distribution MWD is 2~3. In this embodiment, the inorganic filler is calcium carbonate. In the present embodiment, the modified tetrapod-shaped zinc oxide whiskers are γ-aminopropyltriethoxysilane surface-modified tetrapod-shaped zinc oxide whiskers. Specifically, γ-aminopropyltriethoxysilane is dissolved in an organic solvent to obtain a γ-aminopropyltriethoxysilane solution, the tetrapod-shaped zinc oxide whiskers are dispersed in the γ-aminopropyltriethoxysilane solution, and the solid is separated and collected to obtain the modified tetrapod-shaped zinc oxide whiskers. In this embodiment, the β-crystal nucleating agent is calcium pimelate. In this embodiment, the antioxidant is antioxidant 1010. In this embodiment, the preparation method of the low shrinkage modified polypropylene material comprises the following steps: 1) First, put the polypropylene copolymer, metallocene linear high-density polyethylene and inorganic filler into a high-speed mixer and mix them at 85°C for 15 minutes; 2) Add modified tetrapod-shaped zinc oxide whiskers, β-crystal nucleating agent, and antioxidant; continue mixing for 8 minutes; 3) The mixed material is added into a twin-screw extruder with a temperature of 200° C. in each zone for extrusion granulation to obtain a modified polypropylene material. Example 3 A low shrinkage modified polypropylene material comprises the following raw materials in parts by weight: 60 parts of polypropylene copolymer, 15 parts of metallocene linear high-density polyethylene, 15 parts of inorganic filler, 3 parts of modified four-needle zinc oxide whiskers, 0.9 parts of beta crystal nucleating agent and 1 part of antioxidant. In this embodiment, the polypropylene copolymer is copolymerized polypropylene K7726H, and the melt flow rate of copolymerized polypropylene K7726H under the test conditions of 230° C.×2.16 kg is 26 g / 10 min. In this embodiment, the density of the metallocene linear high-density polyethylene is 0.94-0.96 g / cm 3, molecular weight is 80000~120000g / mol, and molecular weight distribution MWD is 2~3. In this embodiment, the inorganic filler is barium sulfate. In the present embodiment, the modified tetrapod-shaped zinc oxide whiskers are γ-aminopropyltriethoxysilane surface-modified tetrapod-shaped zinc oxide whiskers. Specifically, γ-aminopropyltriethoxysilane is dissolved in an organic solvent to obtain a γ-aminopropyltriethoxysilane solution, the tetrapod-shaped zinc oxide whiskers are dispersed in the γ-aminopropyltriethoxysilane solution, and the solid is separated and collected to obtain the modified tetrapod-shaped zinc oxide whiskers. In this embodiment, the β-crystal nucleating agent is a rare earth β-nucleating agent. In this embodiment, the antioxidant is antioxidant 168. In this embodiment, the preparation method of the low shrinkage modified polypropylene material comprises the following steps: 1) First, put the polypropylene copolymer, metallocene linear high-density polyethylene and inorganic filler into a high-speed mixer and mix them at 85°C for 15 minutes; 2) Add modified tetrapod-shaped zinc oxide whiskers, β-crystal nucleating agent, and antioxidant; continue mixing for 8 minutes; 3) The mixed material is added into a twin-screw extruder with a temperature of 200° C. in each zone for extrusion granulation to obtain a modified polypropylene material. Example 4 A low-shrinkage modified polypropylene material comprises the following raw materials in parts by weight: 70 parts of polypropylene copolymer, 12 parts of metallocene linear high-density polyethylene, 18 parts of inorganic filler, 3 parts of modified four-needle zinc oxide whiskers, 0.9 parts of beta crystal nucleating agent and 1 part of antioxidant. In this embodiment, the polypropylene copolymer is copolymerized polypropylene K7726H, and the melt flow rate of copolymerized polypropylene K7726H under the test conditions of 230° C.×2.16 kg is 26 g / 10 min. In this embodiment, the density of the metallocene linear high-density polyethylene is 0.94-0.96 g / cm 3 , molecular weight is 80000~120000g / mol, and molecular weight distribution MWD is 2~3. In this embodiment, the inorganic filler is talcum powder. In the present embodiment, the modified tetrapod-shaped zinc oxide whiskers are γ-aminopropyltriethoxysilane surface-modified tetrapod-shaped zinc oxide whiskers. Specifically, γ-aminopropyltriethoxysilane is dissolved in an organic solvent to obtain a γ-aminopropyltriethoxysilane solution, the tetrapod-shaped zinc oxide whiskers are dispersed in the γ-aminopropyltriethoxysilane solution, and the solid is separated and collected to obtain the modified tetrapod-shaped zinc oxide whiskers. In this embodiment, the β-crystal nucleating agent is calcium pimelate. In this embodiment, the antioxidant is antioxidant 1010. In this embodiment, the preparation method of the low shrinkage modified polypropylene material comprises the following steps: 1) First, put the polypropylene copolymer, metallocene linear high-density polyethylene and inorganic filler into a high-speed mixer and mix them at 85°C for 15 minutes; 2) Add modified tetrapod-shaped zinc oxide whiskers, β-crystal nucleating agent, and antioxidant; continue mixing for 8 minutes; 3) The mixed material is added into a twin-screw extruder with a temperature of 200° C. in each zone for extrusion granulation to obtain a modified polypropylene material. Example 5 A low shrinkage modified polypropylene material comprises the following raw materials in parts by weight: 80 parts of polypropylene copolymer, 10 parts of metallocene linear high-density polyethylene, 20 parts of inorganic filler, 2 parts of modified four-needle zinc oxide whisker, 0.8 parts of beta crystal nucleating agent and 2 parts of antioxidant. In this embodiment, the polypropylene copolymer is copolymerized polypropylene K7726H, and the melt flow rate of copolymerized polypropylene K7726H under the test conditions of 230° C.×2.16 kg is 26 g / 10 min. In this embodiment, the density of the metallocene linear high-density polyethylene is 0.94-0.96 g / cm 3 , molecular weight is 80000~120000g / mol, and molecular weight distribution MWD is 2~3. In this embodiment, the inorganic filler is calcium carbonate. In the present embodiment, the modified tetrapod-shaped zinc oxide whiskers are γ-aminopropyltriethoxysilane surface-modified tetrapod-shaped zinc oxide whiskers. Specifically, γ-aminopropyltriethoxysilane is dissolved in an organic solvent to obtain a γ-aminopropyltriethoxysilane solution, the tetrapod-shaped zinc oxide whiskers are dispersed in the γ-aminopropyltriethoxysilane solution, and the solid is separated and collected to obtain the modified tetrapod-shaped zinc oxide whiskers. In this embodiment, the β-crystal nucleating agent is a rare earth β-nucleating agent. In this embodiment, the antioxidant is antioxidant 168. In this embodiment, the preparation method of the low shrinkage modified polypropylene material comprises the following steps: 1) First, put the polypropylene copolymer, metallocene linear high-density polyethylene and inorganic filler into a high-speed mixer and mix them at 85°C for 15 minutes; 2) Add modified tetrapod-shaped zinc oxide whiskers, β-crystal nucleating agent, and antioxidant; continue mixing for 8 minutes; 3) The mixed material is added into a twin-screw extruder with a temperature of 200° C. in each zone for extrusion granulation to obtain a modified polypropylene material. The modified polypropylene materials obtained in Examples 1 to 5 were tested for shrinkage according to GB / T17037.4-2003. The results are shown in Table 1: Table 1 Group Example 1 Example 2 Example 3 Example 4 Example 5 Transverse shrinkage 0.72％ 0.68％ 0.64％ 0.56％ 0.59％ Longitudinal shrinkage 0.68％ 0.65％ 0.66％ 0.62％ 0.58％ The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A low shrinkage modified polypropylene material, characterized in that: The invention comprises the following raw materials in parts by weight: 40 to 80 parts of polypropylene copolymer, 10 to 20 parts of metallocene linear high-density polyethylene, 10 to 20 parts of inorganic filler, 2 to 5 parts of modified four-needle zinc oxide whisker, 0.8 to 1.2 parts of beta crystal nucleating agent and 1 to 2 parts of antioxidant.

2. The low shrinkage modified polypropylene material according to claim 1, characterized in that: The polypropylene copolymer is copolymerized polypropylene K7726H, and the melt flow rate of copolymerized polypropylene K7726H under the test conditions of 230° C.×2.16 kg is 26 g / 10 min.

3. The low shrinkage modified polypropylene material according to claim 1, characterized in that: The density of the metallocene linear high-density polyethylene is 0.94-0.96 g / cm 3 , molecular weight is 200000~300000g / mol, and molecular weight distribution MWD is 2~3.

4. The low shrinkage modified polypropylene material according to claim 1, characterized in that: The inorganic filler is one of talcum powder, calcium carbonate and barium sulfate.

5. The low shrinkage modified polypropylene material according to claim 1, characterized in that: The modified tetrapod-shaped zinc oxide whisker is a tetrapod-shaped zinc oxide whisker surface-modified with γ-aminopropyltriethoxysilane. Specifically, γ-aminopropyltriethoxysilane is dissolved in an organic solvent to obtain a γ-aminopropyltriethoxysilane solution, the tetrapod-shaped zinc oxide whisker is dispersed in the γ-aminopropyltriethoxysilane solution, and the solid is separated and collected to obtain the modified tetrapod-shaped zinc oxide whisker.

6. The low shrinkage modified polypropylene material according to claim 1, characterized in that: The β-crystal nucleating agent is one of calcium stearate / pimelic acid complex, calcium pimelate, and rare earth β-nucleating agent.

7. The low shrinkage modified polypropylene material according to claim 1, characterized in that: The antioxidant is antioxidant 1010 or antioxidant 168.

8. The low shrinkage modified polypropylene material according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: 1) First, put 40-80 parts of polypropylene copolymer, 10-20 parts of metallocene linear high-density polyethylene, and 10-20 parts of inorganic filler into a high-speed mixer, and mix them at 80-90° C. for 10-20 minutes; 2) Add 2-5 parts of modified tetrapod-shaped zinc oxide whiskers, 0.8-1.2 parts of β-crystal nucleating agent, and 1-2 parts of antioxidant; continue mixing for 6-10 minutes; 3) The mixed material is added into a twin-screw extruder with each zone temperature of 190-210° C. for extrusion granulation to obtain a modified polypropylene material.