A low-linearity polypropylene talc composite material, its preparation method and application

Abstract

This invention relates to the field of polymer materials technology. It discloses a low-linearity polypropylene-talc composite material, its preparation method, and its applications. The material comprises the following raw materials in weight percentages: polypropylene resin: 50-65%, modified talc: 15-25%, ethylene-octene copolymer resin: 10-15%, modified flat glass fiber: 5-15%, basic magnesium sulfate whiskers: 3-10%, heat stabilizer: 0.3-1%, and antioxidant: 0.1-0.5%. This composite material exhibits advantages such as a low coefficient of linear expansion, excellent surface tension, and superior mechanical properties.

Description

Technical Field

[0001] This invention relates to the technical field of polymer materials, specifically to a method for preparing and applying a low-linearity polypropylene talc composite material. Background Technology

[0002] To address the global challenges of energy conservation, emission reduction, and improved driving range, the automotive industry is steadfastly moving towards lightweighting. In this strategic transformation, plastic materials play an indispensable and crucial role. Their lightweight nature directly reduces weight, and integrated design combines multiple parts. Furthermore, high-performance plastics have already replaced some metals in the manufacture of exterior components such as doors and tailgates, becoming a key driving force for lightweighting development.

[0003] Polypropylene (PP), as a common general-purpose plastic, has advantages such as wide availability, low cost, excellent chemical resistance, and good processing performance, showing promising application prospects in automotive materials. However, the application of this material in automotive applications also has the following problems: First, the intrinsic linear expansion coefficient of the material is relatively high (≥120×10). -6 ℃ -1 This coefficient can easily cause shrinkage and warping of products, affecting dimensional stability and hindering widespread use. Therefore, this coefficient should generally be ≤50×10. -6 ℃ -1 (With 30% filler); secondly, the intrinsic surface tension of the material is low (≤30mN·m). -1 The material cannot be directly painted later and requires additional treatment through corona treatment, baking, etc., which is time-consuming and labor-intensive; thirdly, the material has poor intrinsic impact resistance (notched impact strength ≤7kJ / m). 2 Compared to engineering plastics, it has insufficient modulus (flexural modulus ≤1500MPa), which is not conducive to collision protection and reduces safety.

[0004] Therefore, developing a low-linearity polypropylene / talc composite material is of significant economic value and practical importance for improving the application effect and scope of polypropylene materials in automotive body parts. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a polypropylene / talc composite material with a low coefficient of linear expansion, excellent surface tension, and superior mechanical properties.

[0006] To achieve the above objectives, the solution of the present invention is: A low-linearity polypropylene talc composite material is made from the following raw materials in weight percentages: Polypropylene resin: 50~65% Modified talc: 15~25% Ethylene-octene copolymer resin: 10~15% Modified flat glass fiber: 5~15% Basic magnesium sulfate whiskers: 3~10% Heat stabilizer: 0.3~1% Antioxidant: 0.1~0.5%.

[0007] Further, the modified talc powder is prepared by adding talc powder to a high-speed mixer and stirring, then heating to 70~90℃, then adding sorbic acid and stirring for 5~10 min, then adding silane coupling agent and stirring at 70~90℃ for 5~10 min, then adding aliphatic amide and stirring at 70~90℃ for 5~10 min to obtain modified talc powder.

[0008] Furthermore, in the preparation of the modified talc powder, the silane coupling agent is any one or more of γ-mercaptopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane; the aliphatic amide is oleamide and / or erucamide.

[0009] Furthermore, in the preparation process of the modified talc, the mass of sorbic acid is 3-5% of the mass of talc, the mass of the silane coupling agent is 0.5-2% of the mass of talc, and the mass of the aliphatic amide is 5-10% of the mass of talc.

[0010] Furthermore, the talc powder used in the preparation process of the modified talc powder has a particle size of 1-5 micrometers.

[0011] Further, the modified flat glass fiber is prepared by placing chopped glass fibers in a 0.5~2g / L dopamine hydrochloride solution and stirring at room temperature for 3~6 hours, then adding a modifier and stirring at 50~80℃ for 3~6 hours, washing with deionized water and drying to obtain the modified glass fiber.

[0012] Furthermore, the chopped glass fibers used in the preparation of the modified flat glass fibers have a cross-sectional width of 6-8 micrometers.

[0013] Furthermore, the glycidyl ether modifier used in the preparation of the modified flat glass fiber is ethylene glycol diglycidyl ether and / or 1,4-butanediol diglycidyl ether.

[0014] Furthermore, in the preparation process of the modified flat glass fiber, the mass of the chopped glass fiber is 30-50% of the mass of the dopamine hydrochloride solution, and the mass of the glycidyl ether modifier is 5-10% of the mass of the chopped glass fiber.

[0015] Furthermore, the heat stabilizer is any one or more of calcium stearate, zinc stearate, and magnesium stearate, and the antioxidant is any one or more of antioxidant 1076, antioxidant 1010, and antioxidant 168.

[0016] The method for preparing the above-mentioned low-linearity polypropylene talc composite material includes the following steps: Step 1: Composite modification of talc powder: Talc powder with a particle size of 1-5 micrometers is added to a high-speed mixer and heated to 70-90℃. Then, 3-5% sorbic acid, 0.5-2% silane coupling agent, and 5-10% aliphatic amide by weight of talc powder are added sequentially and stirred in steps to obtain modified talc powder. Step 2, Surface finishing of flat glass fibers: Flat, short-cut glass fibers with a cross-sectional width of 6-8 micrometers were impregnated in a dopamine hydrochloride solution with a concentration of 0.5-2 g / L and stirred at room temperature for 3-6 hours to coat with polydopamine. Then, 5-10% of glycidyl ether modifier by weight of glass fibers was added, and grafting reaction was carried out at 50-80℃ for 3-6 hours. After washing and drying, modified flat glass fibers were obtained. Step 3: Melt blending and granulation: By weight percentage, 50-65% of polypropylene resin, 15-25% of modified talc obtained in step (1), 10-15% of ethylene-octene copolymer resin, 5-15% of modified flat glass fiber obtained in step (2), 3-10% of basic magnesium sulfate whiskers, 0.3-1% of heat stabilizer and 0.1-0.5% of antioxidant are mixed evenly and then melt-extruded and granulated at 170-230°C using a twin-screw extruder to obtain a low-linearity polypropylene / talc composite material.

[0017] The low-linearity polypropylene talc composite material prepared by the above method is used in automotive body parts.

[0018] After adopting the above technical solution, the preparation method of the low linear polypropylene / talc composite material of the present invention has the following advantages: Lower coefficient of linear expansion. Modification of PP material using modified talc, modified glass fiber, and basic magnesium sulfate whiskers reduced the coefficient of linear expansion in both directions of the composite material (with the coefficient of linear expansion in the parallel flow direction remaining approximately 38.4~43.2×10⁻⁶). -6 ℃ -1 The vertical flow direction is basically maintained at 46.6~49.5×10. -6 ℃ -1 The average value remained between 42.5 and 46.4 × 10⁻⁶. -6 ℃ -1The shrinkage and warping of the composite material are basically eliminated, giving the composite material good dimensional stability.

[0019] (2) Excellent surface tension. The talc and glass fiber were modified with aliphatic amides and ethylene glycol diglycidyl ether, which improved the surface tension of the composite material (maintaining a range of approximately 38-42 mN·m). -1 This enhances the adhesion between the composite material surface and the coating (maintaining a level of approximately 0), thus giving the composite material excellent coating capabilities. (3) Excellent mechanical properties. Modification of PP materials using POE resin, talc, glass fiber, and basic magnesium sulfate whiskers not only improves the impact resistance of the composite material (maintaining a strength of approximately 16.5~18.9 kJ / m), but also enhances its overall impact resistance. 2 It also improves the mechanical strength and modulus of the composite material (tensile strength is basically maintained at 28.5~30.6MPa, flexural strength is basically maintained at 30.7~32.4MPa, and flexural modulus is basically maintained at 2639~2852MPa), giving the composite material good mechanical properties. Detailed Implementation

[0020] To further explain the technical solution of the present invention, the present invention will be described in detail below through specific embodiments.

[0021] I. Material Preparation Example 1

[0022] Step 1: Add talc powder with a particle size of 1 micrometer to a high-speed mixer and stir. Then heat to 70°C, add 3 wt% sorbic acid of talc powder and stir for 10 min. Then add 1 wt% γ-aminopropylmethyldiethoxysilane of talc powder and stir at 90°C for 8 min. Then add 10 wt% oleamide of talc powder and stir at 90°C for 10 min to obtain modified talc powder. Step 2: Short glass fibers with a cross-sectional width of 6 micrometers were placed in a 2 g / L dopamine hydrochloride solution and stirred at room temperature for 4 hours (the mass ratio of short glass fibers to dopamine hydrochloride solution was 1:2). Then, 6 wt% of ethylene glycol diglycidyl ether was added to the short glass fibers and stirred at 80°C for 3 hours. The mixture was then washed with deionized water and dried to obtain modified glass fibers. Step 3: Mix 57% PP resin, 20% modified talc, 12.5% ​​POE resin, 5% modified glass fiber, 5% basic magnesium sulfate whiskers, 0.3% calcium stearate and 0.2% antioxidant 1010 by mass ratio, and then melt extrude and granulate the mixture through a twin-screw extruder at extrusion temperatures of 170, 195, 220, 230, 225 and 225℃ to obtain a low linear polypropylene / talc composite material. Example 2

[0023] Step 1: Add talc powder with a particle size of 3 micrometers to a high-speed mixer and stir. Then heat to 85°C, add 5 wt% sorbic acid of talc powder and stir for 8 min. Then add 0.5 wt% γ-mercaptopropyltrimethoxysilane of talc powder and stir at 70°C for 6 min. Then add 5 wt% erucamide of talc powder and stir at 80°C for 7 min to obtain modified talc powder. Step 2: Short glass fibers with a cross-sectional width of 8 micrometers were placed in a 1 g / L dopamine hydrochloride solution and stirred at room temperature for 3 hours (the mass ratio of short glass fibers to dopamine hydrochloride solution was 3:10). Then, 10 wt% of 1,4-butanediol diglycidyl ether was added to the short glass fibers and stirred at 60°C for 3 hours. The mixture was then washed with deionized water and dried to obtain modified glass fibers. Step 3: Mix 60% PP resin, 15% modified talc, 10% POE resin, 10% modified glass fiber, 4% basic magnesium sulfate whiskers, 0.5% zinc stearate and 0.5% antioxidant 168 by mass ratio, and then melt extrude and granulate the mixture through a twin-screw extruder at extrusion temperatures of 170, 193, 222, 230, 228 and 224℃ to obtain a low linear polypropylene / talc composite material. Example 3

[0024] Step 1: Add talc powder with a particle size of 5 micrometers to a high-speed mixer and stir. Then heat to 75°C, add sorbic acid at 4 wt% of the talc powder mass and stir for 6 min. Then add N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane at 1.2 wt% of the talc powder mass and stir at 75°C for 8 min. Then add oleic acid amide at 8 wt% of the talc powder mass and stir at 85°C for another 8 min to obtain modified talc powder. Step 2: Short glass fibers with a cross-sectional width of 6 micrometers were placed in a 1.5 g / L dopamine hydrochloride solution and stirred at room temperature for 5 hours (the mass ratio of short glass fibers to dopamine hydrochloride solution was 2:5). Then, 8 wt% of 1,4-butanediol diglycidyl ether was added to the short glass fibers and stirred at 70°C for 3 hours. The mixture was then washed with deionized water and dried to obtain modified glass fibers. Step 3: Mix 50% PP resin, 25% modified talc, 15% POE resin, 5.5% modified glass fiber, 3% basic magnesium sulfate whiskers, 1% magnesium stearate and 0.5% antioxidant 1076 by mass ratio, and then melt extrude and granulate the mixture through a twin-screw extruder at extrusion temperatures of 170, 196, 228, 230, 226 and 225℃ to obtain a low linear polypropylene / talc composite material. Comparative Example 1

[0025] In this comparative example, PP resin was extruded and granulated using a twin-screw extruder at processing temperatures of 170, 195, 220, 230, 225, and 225°C to prepare ordinary PP materials. Comparative Example 2

[0026] The difference from Example 1 is that the talc and chopped glass fibers in this comparative example are not modified in steps 1 and 2, but are directly added to prepare the polypropylene / talc composite material. Comparative Example 3

[0027] The difference from Example 1 is that modified glass fiber is not added in this comparative example. Instead, 57% PP resin, 25% modified talc, 12.5% ​​POE resin, 5% basic magnesium sulfate whiskers, 0.3% calcium stearate and 0.2% antioxidant 1010 are mixed and then melt-extruded and granulated using a twin-screw extruder at extrusion temperatures of 170, 195, 220, 230, 225 and 225°C to obtain polypropylene / talc composite materials. Comparative Example 4

[0028] The difference from Example 1 is that basic magnesium sulfate whiskers are not added in this comparative example. Instead, 57% PP resin, 25% modified talc, 12.5% ​​POE resin, 5% modified glass fiber, 0.3% calcium stearate and 0.2% antioxidant 1010 are mixed and then melt-extruded and granulated using a twin-screw extruder at extrusion temperatures of 170, 195, 220, 230, 225 and 225°C to obtain a polypropylene / talc composite material. Comparative Example 5

[0029] The difference from Example 1 is that the chopped glass fibers in this comparative example are cylindrical, while the other conditions remain the same, to prepare a polypropylene / talc composite material. Comparative Example 6

[0030] The difference from Example 1 is that steps (1) and (2) are omitted in this comparative example, and the modified glass fiber and basic magnesium sulfate whiskers are replaced with unmodified talc (i.e., the proportion of unmodified talc is adjusted to 30%), while the other conditions remain unchanged, to prepare polypropylene / talc composite material. Comparative Example 7

[0031] The difference from Example 1 is that steps (1) and (2) are omitted in this comparative example, and the modified glass fiber and modified talc are replaced with basic magnesium sulfate whiskers (i.e., the basic magnesium sulfate whiskers are 30%), while the other conditions remain unchanged, to prepare polypropylene / basic magnesium sulfate whisker composite material.

[0032] II. Performance Testing The polypropylene / talc composite materials prepared in each embodiment and comparative example were made into test strips according to the relevant performance standards below. The linear expansion coefficient (ISO 11359-2:2021), dyne value (ISO 8296-2008), adhesion grade (GB / T 9286-2021), tensile strength (GB / T 1040.2-2006), notched impact strength (GB / T 1843-2008), flexural strength and modulus (GB / T 9341-2024), and density (GB / T 1033.1-2008) of the polypropylene / talc composite materials were measured. At the same time, the shrinkage and warping of the products were observed. The results are shown in Table 1.

[0033] Table 1. Overview of the properties of polypropylene / talc composites

[0034] As can be seen from the data in Table 1, the low-linearity polypropylene / talc composites prepared in Examples 1-3 exhibit excellent performance, with a linear expansion coefficient (FD direction) not exceeding 43.2 × 10⁻⁶. -6 ℃ -1 It remained basically between 38.4 and 43.2 × 10. -6 ℃ -1 The linear expansion coefficient (TD direction) is no higher than 49.5 × 10⁻⁶. -6 ℃ -1 It remained basically at 46.6~49.5×10 -6 ℃ -1 The average linear expansion coefficient is no higher than 46.4 × 10⁻⁶. -6 ℃ -1 It remained basically at 42.5~46.4×10 -6 ℃ -1 The dyne value is not less than 38 mN·m -1 It basically remained at 38~42 mN·m -1 The adhesion rating reaches level 0, the tensile strength is not less than 28.5 MPa, and it is basically maintained between 28.5 and 30.6 MPa. The notched impact strength is not less than 16.5 kJ / m. 2 It remained basically between 16.5 and 18.9 kJ / m 2The flexural strength is not less than 30.7 MPa, generally maintained between 30.7 and 32.4 MPa; the flexural modulus is not less than 2639 MPa, generally maintained between 2639 and 2852 MPa; and the density is not higher than 1.123 g / cm³. 3 It remained basically between 1.099 and 1.123 g / cm³. 3 The shrinkage and warping phenomenon disappears.

[0035] As can be seen from Comparative Example 1, PP material has shortcomings such as high linear expansion coefficient, low surface tension, poor toughness, low modulus, and shrinkage warping, making it difficult to effectively apply in automotive body parts. By modifying PP material, these shortcomings are effectively overcome, as shown in Examples 1-3 in Table 1. Compared with Example 1, in Comparative Example 2, without modification by talc and chopped glass fibers, the dyne value and adhesion of the composite material decreased, while shrinkage and warping still occurred. In Comparative Example 3, without the addition of modified glass fibers, the linear expansion coefficient of the composite material increased, while the dyne value, adhesion, and modulus decreased, and shrinkage and warping still occurred. In Comparative Example 4, without the addition of basic magnesium sulfate whiskers, the linear expansion coefficient of the composite material increased, the modulus decreased, and shrinkage and warping still occurred. In Comparative Example 5, with the addition of cylindrical glass fibers, the linear expansion coefficient of the composite material increased, while shrinkage and warping still occurred. In Comparative Example 6, without the addition of modified glass fibers, basic magnesium sulfate whiskers, and unmodified talc, the linear expansion coefficient of the composite material increased, while the dyne value and adhesion decreased, and shrinkage and warping also occurred. In Comparative Example 7, without the addition of modified talc and modified glass fibers, the linear expansion coefficient of the composite material increased, while the dyne value and adhesion decreased, and shrinkage and warping also occurred, failing to meet the application requirements.

[0036] The low-linear polypropylene / talc composite material obtained by the preparation method of the low-linear polypropylene / talc composite material of the present invention can meet the requirements of automotive body parts and can be used to manufacture automotive body parts.

[0037] The components of this invention are preferably in the following mass percentages: polypropylene resin: 50-65%, modified talc: 15-25%, ethylene-octene copolymer resin: 10-15%, modified flat glass fiber: 5-15%, basic magnesium sulfate whiskers: 3-10%, heat stabilizer: 0.3-1%, antioxidant: 0.1-0.5%. In the preparation of modified talc, the particle size of the talc is preferably 1-5 micrometers. The mass of sorbic acid used in the preparation of modified talc is preferably 3-5% of the talc mass, the mass of the silane coupling agent is preferably 0.5-2% of the talc mass, and the mass of the aliphatic amide is preferably 5-10% of the talc mass. The silane coupling agent is any one or more of γ-mercaptopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane. The aliphatic amide is oleamide and / or erucamide. In the preparation of modified flat glass fibers, it is preferable to use flat, short-cut glass fibers with a cross-sectional width of 6-8 micrometers as raw materials. The glycidyl ether modifier is preferably ethylene glycol diglycidyl ether and / or 1,4-butanediol diglycidyl ether. The mass of the short-cut glass fibers used in the preparation of the modified flat glass fibers is preferably 30-50% of the mass of the dopamine hydrochloride solution, and the mass of the glycidyl ether modifier is preferably 5-10% of the mass of the short-cut glass fibers. The heat stabilizer can be any one or more of calcium stearate, zinc stearate, and magnesium stearate; the antioxidant can be any one or more of antioxidant 1076, antioxidant 1010, and antioxidant 168.

[0038] The above embodiments are not intended to limit the product form and style of the present invention. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims

1. A low-linearity polypropylene talc composite material, characterized in that: Made from the following raw materials by weight percentage: Polypropylene resin: 50~65% Modified talc: 15~25% Ethylene-octene copolymer resin: 10~15% Modified flat glass fiber: 5~15% Basic magnesium sulfate whiskers: 3~10% Heat stabilizer: 0.3~1% Antioxidant: 0.1~0.5%.

2. The low-linearity polypropylene talc composite material according to claim 1, characterized in that: The modified talc powder is prepared by adding talc powder to a high-speed mixer and stirring, then heating to 70-90°C, then adding sorbic acid and stirring for 5-10 minutes, then adding silane coupling agent and stirring for 5-10 minutes at 70-90°C, then adding aliphatic amide and stirring for 5-10 minutes at 70-90°C to obtain modified talc powder.

3. The low-linearity polypropylene talc composite material according to claim 2, characterized in that: The silane coupling agent used in the preparation of the modified talc powder is any one or more of γ-mercaptopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, and N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane; the aliphatic amide is oleamide and / or erucamide.

4. The low-linearity polypropylene talc composite material according to claim 2, characterized in that: In the preparation process of the modified talc, the mass of sorbic acid is 3-5% of the mass of talc, the mass of the silane coupling agent is 0.5-2% of the mass of talc, and the mass of the aliphatic amide is 5-10% of the mass of talc.

5. The low-linearity polypropylene talc composite material according to claim 2, characterized in that: The talc powder used in the preparation process of the modified talc powder has a particle size of 1~5 micrometers.

6. The low-linearity polypropylene talc composite material according to claim 1, characterized in that: The modified flat glass fiber is prepared by placing short glass fibers in a 0.5~2g / L dopamine hydrochloride solution and stirring at room temperature for 3~6 hours, then adding a modifier and stirring at 50~80℃ for 3~6 hours, washing with deionized water and drying to obtain the modified glass fiber.

7. The low-linearity polypropylene talc composite material according to claim 6, characterized in that: The chopped glass fibers used in the preparation of the modified flat glass fibers have a cross-sectional width of 6-8 micrometers.

8. The low-linearity polypropylene talc composite material according to claim 6, characterized in that: The glycidyl ether modifier used in the preparation of the modified flat glass fiber is ethylene glycol diglycidyl ether and / or 1,4-butanediol diglycidyl ether.

9. The low-linearity polypropylene talc composite material according to claim 6, characterized in that: In the preparation of the modified flat glass fiber, the mass of the chopped glass fiber used is 30-50% of the mass of the dopamine hydrochloride solution, and the mass of the glycidyl ether modifier is 5-10% of the mass of the chopped glass fiber.

10. The low-linearity polypropylene talc composite material according to claim 1, characterized in that: The heat stabilizer is any one or more of calcium stearate, zinc stearate, and magnesium stearate, and the antioxidant is any one or more of antioxidant 1076, antioxidant 1010, and antioxidant 168.

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