High-strength easy-to-spray polypropylene material and preparation method thereof

Abstract

This invention discloses a high-strength, easy-to-spray polypropylene material and its preparation method, comprising the following parts by weight: 50-70 parts by weight of PP resin, 5-10 parts by weight of toughening agent, 20-25 parts by weight of talc, 3-5 parts by weight of compatibilizer, 0.1-0.5 parts by weight of primary antioxidant, 0.1-0.5 parts by weight of secondary antioxidant, 0.3-0.5 parts by weight of lubricant, 2-5 parts by weight of polyvinyl alcohol (PVA2499), and 2-10 parts by weight of 3-aminopropyltrimethoxysilane. The polypropylene material prepared by this invention maintains high strength while retaining high toughness, and also has high surface adhesion, making it suitable for applications requiring painting, such as automotive exteriors. It significantly improves upon the problem of limited application of polypropylene materials due to difficult spraying, greatly contributing to the expansion of its application areas. The preparation process of the high-strength, easy-to-spray polypropylene material proposed in this invention is relatively simple and allows for stable mass production.

Description

Technical Field

[0001] This invention belongs to the field of polymer modification and relates to a high-strength, easy-to-spray polypropylene material and its preparation method. Background Technology

[0002] Polypropylene (PP) is a general-purpose plastic widely used in automobiles, home appliances and other fields. However, its low strength, poor toughness and low surface energy, which lead to poor coating adhesion, limit its application in high-performance fields.

[0003] Existing technologies improve performance by adding reinforcing materials, elastomers, or surface treatments, but it is difficult to simultaneously achieve high strength, high toughness, and ease of spraying, and problems such as decreased processing performance and unstable treatment results exist.

[0004] Therefore, it is of great significance to develop a polypropylene material that combines high strength, high toughness, and easy spraying properties. Summary of the Invention

[0005] To overcome the aforementioned problems in the prior art, this invention proposes a high-strength, easy-to-spray polypropylene material and its preparation method. The high-strength, easy-to-spray polypropylene material provided by this invention maintains high strength while also possessing high toughness and excellent surface adhesion, making it suitable for applications requiring painting, such as automotive exteriors.

[0006] This invention is achieved through the following technical solution: A high-strength, easy-to-spray polypropylene material, comprising: 50-70 parts by weight of PP resin, 5-10 parts by weight of toughening agent, 20-25 parts by weight of talc, 3-5 parts by weight of compatibilizer, 0.1-0.5 parts by weight of primary antioxidant, 0.1-0.5 parts by weight of secondary antioxidant, 0.3-0.5 parts by weight of lubricant, 0-5 parts by weight of polyvinyl alcohol (PVA2499), and 2-10 parts by weight of 3-aminopropyltrimethoxysilane.

[0007] Furthermore, under the test conditions of 230 ℃ × 2.16 kg, the melt flow rate of the PP resin is 20-30 g / 10 min; the molecular weight of the PP resin is between 80,000 and 150,000.

[0008] Furthermore, the toughening agent is one or both of the polyolefin elastomers that are copolymers of ethylene-hexene and ethylene-octene.

[0009] Furthermore, the talc powder is talc powder with a mesh size of 2000-2500.

[0010] Furthermore, the compatibilizer is maleic anhydride-grafted polypropylene.

[0011] Furthermore, the primary antioxidant is a hindered phenolic antioxidant, the secondary antioxidant is a phosphite antioxidant, and the lubricant is calcium stearate.

[0012] A method for preparing a high-strength, easily sprayable polypropylene material, the method specifically comprising: (1) Weigh and dry the PP resin, toughening agent, talc, compatibilizer, main antioxidant, auxiliary antioxidant, lubricant, polyvinyl alcohol PVA2499, and 3-aminopropyltrimethoxysilane according to the specified ratio; (2) The raw materials dried in step (1) are mixed and continuously and evenly added to the main feed cylinder of the twin-screw extruder. The extruded strips are cooled by a water tank and then granulated to obtain the high-strength, easy-to-spray polypropylene material.

[0013] Furthermore, the twin-screw extruder has a rotational speed of 350-500 rpm, a screw diameter of 16-35 mm, and a length-to-diameter ratio (L / D) of 36-48.

[0014] Furthermore, the temperatures of the conveying section, melting section, mixing section, exhaust section, and homogenization section of the twin-screw extruder are 190 ℃, 200 ℃, 210 ℃, 200 ℃, and 200 ℃, respectively. The beneficial effects of this invention are: The polypropylene material prepared by this invention, with the addition of a certain amount of talc and toughening agent, is modified with 3-aminopropyltrimethoxysilane, which enables it to maintain high toughness while possessing high strength. At the same time, 3-aminopropyltrimethoxysilane ensures that it has higher surface adhesion, making it suitable for scenarios such as automotive exteriors that require painting. This greatly improves the problem of polypropylene materials being limited in application due to the difficulty of painting, and is of great help in expanding the application fields.

[0015] The method for preparing high-strength, easy-to-spray polypropylene material proposed in this invention is relatively simple and can be used for stable mass production. Detailed Implementation

[0016] To facilitate understanding of the present invention, specific embodiments are described below in more detail. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0017] A high-strength, easy-to-spray polypropylene material, comprising: 50-70 parts by weight of PP resin, 5-10 parts by weight of toughening agent, 20-25 parts by weight of talc, 3-5 parts by weight of compatibilizer, 0.1-0.5 parts by weight of primary antioxidant, 0.1-0.5 parts by weight of secondary antioxidant, 0.3-0.5 parts by weight of lubricant, 0-5 parts by weight of polyvinyl alcohol (PVA2499), and 2-10 parts by weight of 3-aminopropyltrimethoxysilane.

[0018] Under test conditions of 230 ℃ × 2.16 kg, the melt flow rate of the PP resin is 20-30 g / 10 min; the molecular weight of the PP resin is between 80,000 and 150,000.

[0019] The toughening agent is one or both of the following: ethylene-hexene copolymer and ethylene-octene copolymer polyolefin elastomer.

[0020] The talc powder is 2000-2500 mesh. The compatibilizer is maleic anhydride-grafted polypropylene (PP-g-MAH); the main antioxidant is a hindered phenolic antioxidant, the secondary antioxidant is a phosphite antioxidant, and the lubricant is calcium stearate.

[0021] Specifically, the raw materials used in this invention are as follows: PP resin: PP-HP500NB, manufactured by Bora Basel; toughening agent: polyolefin elastomer POE-6588, manufactured by Daelim, South Korea; talc: HTP-ultra-5L, manufactured by Immifabi; compatibilizer: PP-g-MAH; primary antioxidant 1010: hindered phenolic antioxidant; secondary antioxidant 168: phosphite secondary antioxidant; lubricant: calcium stearate; polyvinyl alcohol PVA2499: PVA2499; 3-aminopropyltrimethoxysilane: Sinopharm Chemical Reagent.

[0022] The chemical structural formula of 3-aminopropyltrimethoxysilane is as follows: .

[0023] Using the raw materials of the above type, high-strength, easy-to-spray polypropylene materials were prepared by selecting different proportions. The specific formulations of different embodiments are shown in Table 1.

[0024] The particle material prepared according to the method disclosed in this embodiment is dried in a forced-air oven at 80 ℃ for 3 to 5 hours, and then the dried particle material is injection molded into GB / T standard strips and color plates at an injection temperature of 210 ℃. The performance of the injection molded strips is tested after being placed at 50% relative humidity and 23 ℃ for 48 hours.

[0025] Melt flow rate test: conducted according to GB / T 3682.1-2018 standard, plastic particles, 230 ℃ * 2.16 kg.

[0026] Tensile strength test: conducted according to GB / T 1040.1-2018 standard.

[0027] Bending strength test: conducted in accordance with GB / T 9341-2008 standard.

[0028] Notched impact strength test: conducted according to GB / T 1843-2008 standard.

[0029] The mechanical properties of materials are evaluated by measuring the tensile strength, flexural strength, and notched impact strength obtained from tests.

[0030] Contact angle test: performed according to ISO 19403-2:2017 standard.

[0031] Dyne value: according to ISO 8296 standard.

[0032] Cross-cut test: Performed according to ISO 2409 standard.

[0033] The surface adhesion (surface energy) of a material is evaluated by measuring the contact angle, dyne value, and cross-cut adhesion test values.

[0034] Performance tests were conducted according to the above standards, and the test results are shown in Table 2.

[0035] Table 1 Formulations of high-strength, easy-to-apply polypropylene materials in different embodiments PP-HP500NB 55 55 55 55 70 65 60 55 60 55 55 POE-6588 10 10 10 10 10 10 10 10 10 10 10 Talc HTP-ultra-5L 20 20 20 20 20 20 20 20 20 20 20 PP-g-MAH 5 5 5 5 5 5 5 5 5 5 3-Aminopropyltrimethoxysilane 10 8 6 5 5 2 4 PVA2499 0 2 4 5 5 10 8 6 Main antioxidant 1010 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Co-oxidant 168 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Calcium stearate 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Table 2 Test Results Melt Flow Index 5.5 4.2 7.4 6.8 10.3 9.7 8.2 7.2 5.7 4.6 7.2 Tensile strength 38.2 39.3 34.5 36.3 26.2 27.1 30.2 28.3 24.3 27.5 28.2 Bending strength 42.3 41.3 37.2 41.3 31.3 32.2 35.2 33.6 31.9 36.2 34.3 Flexural modulus 2788 2756 2520 2753 2015 2034 2352 2284 2020 2590 2501 Cantilever beam notch impact strength 8.8 10.1 16.3 14.3 15.6 17.8 17.7 15.3 13.2 14.5 15.8 Contact angle 75 82 79 81 102 99 91 95 89 92 85 Dyne value 32 31 31 31 26 26 28 27 29 28 30 Hundred-grid knife test Level 2 Level 2 Level 2 Level 2 Level 4 Level 4 Level 3 Level 4 Level 3 Level 3 Level 3

[0036] The performance differences between Examples 1-4 and Comparative Examples 1-2 mainly stem from the synergistic evolution of interface modification and phase structure: In Comparative Example 1, talc powder and PP matrix are only physically adsorbed together, resulting in a large number of defects at the interface and coarse particle size of the POE dispersed phase, which limits the mechanical properties; In Comparative Example 2, when only 5 parts of PP-g-MAH are added, the maleic anhydride groups interact with POE to refine its particle size, while partially improving the interfacial bonding of talc powder, resulting in a slight increase in impact and tensile strength. In Examples 1-4, the silane coupling agent 3-aminopropyltrimethoxysilane forms covalent bonds (Si-O-Si) with the hydroxyl groups on the surface of talc. Adding 10 parts of 3-aminopropyltrimethoxysilane creates a dense three-dimensional network, significantly increasing the flexural modulus but decreasing the impact toughness. Introducing PVA2499 (especially at 2-5 parts) causes its molten microfibers to undergo esterification, forming a fiber-like reinforcement structure in the matrix. In Examples 2-3, balancing silane crosslinking and PVA microfiber toughening achieves high modulus while maintaining a certain impact strength. In Example 4, the synergistic effect of silane crosslinking and PVA microfibers exhibits optimal overall performance. This gradient interface design of "chemical crosslinking-physical reinforcement," through the multi-scale effects of 3-aminopropyltrimethoxysilane nanoscale bonding, PP-g-MAH interface compatibilization, and PVA microfiber reinforcement, achieves performance regulation from simple reinforcement to a balance between rigidity and toughness.

[0037] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-strength, easily sprayable polypropylene material, characterized in that, The high-strength, easy-to-spray polypropylene material comprises: 50-70 parts by weight of PP resin, 5-10 parts by weight of toughening agent, 20-25 parts by weight of talc, 3-5 parts by weight of compatibilizer, 0.1-0.5 parts by weight of primary antioxidant, 0.1-0.5 parts by weight of secondary antioxidant, 0.3-0.5 parts by weight of lubricant, 0-5 parts by weight of polyvinyl alcohol (PVA2499), and 2-10 parts by weight of 3-aminopropyltrimethoxysilane.

2. The high-strength, easy-to-spray polypropylene material according to claim 1, characterized in that, Under test conditions of 230 ℃ × 2.16 kg, the melt flow rate of the PP resin is 20-30 g / 10 min; the molecular weight of the PP resin is between 80,000 and 150,000.

3. The high-strength, easy-to-spray polypropylene material according to claim 1, characterized in that, The toughening agent is one or both of the following: ethylene-hexene copolymer and ethylene-octene copolymer polyolefin elastomer.

4. The high-strength, easy-to-spray polypropylene material according to claim 1, characterized in that, The talc powder is talc powder with a mesh size of 2000-2500.

5. The high-strength, easy-to-spray polypropylene material according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene.

6. The high-strength, easy-to-spray polypropylene material according to claim 1, characterized in that, The primary antioxidant is a hindered phenolic antioxidant, the secondary antioxidant is a phosphite antioxidant, and the lubricant is calcium stearate.

7. A method for preparing a high-strength, easily sprayable polypropylene material, used to prepare the high-strength, easily sprayable polypropylene material as described in any one of claims 1-6, characterized in that, The method specifically includes: (1) Weigh and dry the PP resin, toughening agent, talc, compatibilizer, main antioxidant, auxiliary antioxidant, lubricant, polyvinyl alcohol PVA2499, and 3-aminopropyltrimethoxysilane according to the specified ratio; (2) The raw materials dried in step (1) are mixed and continuously and evenly added to the main feed cylinder of the twin-screw extruder. The extruded strips are cooled by a water tank and then granulated to obtain the high-strength, easy-to-spray polypropylene material.

8. The method for preparing a high-strength, easily sprayable polypropylene material according to claim 7, characterized in that, The twin-screw extruder has a rotational speed of 350-500 rpm, a screw diameter of 16-35 mm, and a length-to-diameter ratio (L / D) of 36-48.

9. The method for preparing a high-strength, easily sprayable polypropylene material according to claim 7, characterized in that, The temperatures of the conveying section, melting section, mixing section, exhaust section, and homogenization section of the twin-screw extruder are 190 ℃, 200 ℃, 210 ℃, 200 ℃, and 200 ℃, respectively.