Light aging resistant foamed polypropylene material and preparation method thereof

Abstract

The present invention discloses a light-resistant foamed polypropylene material, which is composed of 67.6-97.1% polypropylene, 0.01-0.2% zinc borate, 0.01-0.2% erucamide, 1-5% carbon aerogel, 0.5-2% coupling agent, 0.1-2% composite light and heat stabilizer, and 0.1-2% black masterbatch. The present invention modifies polypropylene for weather resistance by adopting a composite scheme of porous carbon aerogel and composite light and heat stabilizer, and can meet the high requirements of automotive exterior parts for the light resistance of materials. The present invention solves the problem that foamed polypropylene composite materials degrade quickly under light aging conditions, greatly improves the long-term light aging resistance of foamed polypropylene composite materials, and can be applied in automotive exterior plastic parts.

Description

Technical Field

[0001] The invention relates to the technical field of polypropylene composite materials, and in particular to a light aging resistant foamed polypropylene material and a preparation method thereof. Background Art

[0002] With the 2060 carbon neutrality goal in mind, green and efficient new energy vehicles are attracting increasing attention from researchers. The rapid development of new energy vehicles in the Chinese market requires materials with lighter density and better overall performance to increase range and reduce energy consumption. Expanded polypropylene (PP) is widely used in automobiles due to its lightweight, good rigidity, impact resistance, heat resistance, and low cost.

[0003] At present, foamed polypropylene is mainly used in automotive interior instrument panels, trunk linings, air-conditioning group partitions, roofs, door inner panels and bumper linings. However, for the above parts, foamed polypropylene materials do not require high weather resistance requirements. At this stage, there is little research on weather-resistant foamed polypropylene for automotive exteriors. In particular, for automotive exteriors that require high weather resistance (PV3930 non-metallic material weathering test requirements in hot and humid climates must reach more than 800 hours), foamed polypropylene materials are more prone to aging and degradation problems due to their high foaming ratio compared to conventional injection-grade polypropylene materials. It is difficult to meet the light aging requirements of automotive exteriors and faces great challenges. Summary of the Invention

[0004] The present invention aims to provide a light-resistant foamed polypropylene material and a preparation method thereof. The material has excellent light-resistant performance and can be used as a black exterior component for automobiles.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A light-aging-resistant foamed polypropylene material, comprising the following raw materials by weight:

[0007] Polypropylene 67.6-97.1%;

[0008] Zinc borate 0.01-0.2%;

[0009] Erucamide 0.01-0.2%;

[0010] Kaolin 0.05-1%;

[0011] Sodium lauryl sulfate 0.05-1%;

[0012] Carbon aerogel 1-10%;

[0013] Coupling agent 0.5-5%;

[0014] Composite light and heat stabilizer 0.1-5%;

[0015] Black masterbatch 1-10%.

[0016] The polypropylene has a melt flow rate of 0.1 to 3 g / 10 min and is selected from high melt strength polypropylene, preferably one or more commercially available products such as E02S and W331.

[0017] The zinc borate is preferably prepared from Kunshan Shengheng Chemical Materials Co., Ltd. and has a particle size of 3 to 6 μm.

[0018] The erucamide is refined export grade with a purity of ≥99.9%. ZOTN products from Jiangsu are preferred.

[0019] The kaolin has a particle size of 0.1 to 50 μm, preferably ASP200, a product of BASF.

[0020] The sodium lauryl sulfate has a purity of ≥97%. Shanghai Yuanye Biotechnology Co., Ltd. is preferred.

[0021] The carbon aerogel described above is a self-produced product of our company. It is prepared using resorcinol (R) and formaldehyde (F) as raw materials and sodium carbonate (C) as a catalyst. Carbon aerogel has a pearl-string-like disordered porous network structure, characterized by high specific surface area, high electrical conductivity, low density, and a continuous network structure with small pores that are interconnected. It exhibits excellent hydrogen absorption and desorption properties and is one of the lightest solid condensed states. Its porosity is as high as 80-98%, and it possesses unique optical, electrical, and magnetic properties. It can continuously absorb and adsorb substances in polypropylene foam materials.

[0022] The coupling agents are KH550 and KH560, available from Guangzhou Zhanfei Chemical Technology Co., Ltd. KH550 is preferred. Surface treatment with the carbon aerogel coupling agent improves the interfacial bonding between polypropylene and the carbon aerogel, allowing the carbon aerogel to be evenly dispersed in the polypropylene resin.

[0023] The composite light and heat stabilizer is a mixture of an antioxidant and a light stabilizer. The primary antioxidant is a hindered phenol antioxidant, a thioester antioxidant, and / or a phenol-free primary antioxidant, and the secondary antioxidant is a phosphite antioxidant and / or a spirophosphite antioxidant, preferably a spirophosphite antioxidant. The light stabilizer is a hindered amine light stabilizer. Since polypropylene has poor weather resistance and is easily degraded, the addition of a composite light and heat stabilizer is necessary. This composite light and heat stabilizer can prevent the degradation of PP materials during the production process, while improving the heat resistance, light resistance, and color change of polypropylene, effectively meeting the weather resistance requirements of automotive exterior parts for materials. For foamed polypropylene, due to its high foaming ratio, the foamed polypropylene structure is prone to collapse after light aging. Preferably, the composite light and heat stabilizer is a mixture of primary antioxidant 1330, phenol-free primary antioxidant 420, secondary antioxidant 168, light stabilizer 770, and light stabilizer Tinuvin XT55.

[0024] The present invention also discloses a method for preparing a light-aging-resistant foamed polypropylene material, comprising the following steps: stirring carbon aerogel and a coupling agent at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes, uniformly mixing the mixture with polypropylene, a composite light and heat stabilizer, and a black masterbatch in a certain proportion at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes to obtain a mixture A; adding zinc borate and erucamide, mixing uniformly at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes to obtain a mixture B; injecting the B into a reactor, adding kaolin and sodium dodecylsulfonate, and foaming at high temperature and high pressure using carbon dioxide as a foaming agent, with the temperature in the reactor being 140-160° C. and the pressure in the reactor being 2-4 MPa; stirring the reactor with a magnetic stirrer at a frequency of 30-100 Hz, and finally obtaining a black foamed polypropylene material with a foaming ratio of 20 times and high light-aging resistance.

[0025] The light-aging-resistant foamed polypropylene material obtained by the present invention has a foaming ratio of up to 20 times through different formula design combinations, and has good weather resistance. After 800 hours of PV3930 weathering test, there is no obvious powdering and discoloration on the surface of the part, which fully meets the material requirements of automobile exterior parts.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The present invention can select one or more copolymerized polypropylene resins with good low-temperature resistance as the matrix resin according to actual needs. The specific adjustment can be made according to the use environment of the prepared automotive parts. By adopting a compounding scheme of porous carbon aerogel and composite light and heat stabilizer, the light aging resistance of polypropylene is modified, which fully meets the high light aging resistance requirements of automotive exterior black parts. The present invention solves the problem of rapid degradation of ordinary foamed polypropylene composite materials under light aging conditions, greatly improves the long-term light aging resistance of foamed polypropylene composite materials, and can be used in automotive exterior plastic parts.

[0028] (2) The present invention has the characteristics of simple operation, good controllability, low production cost, and easy industrial production. In addition, the scraps of the products prepared by the material can be reused. Therefore, it has good economic and environmental benefits overall. Compared with similar products, the light-aging-resistant foamed polypropylene material prepared by the present invention has better weather resistance. The prepared product can be widely used in black exterior parts of new energy vehicles, and has broad market prospects and high application value. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with embodiment.It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.Those skilled in the art can make modifications or equivalent substitutions based on the understanding of the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and all should be included in the protection scope of the present invention.

[0030] The raw materials used in the specific implementation manner are all purchased from the market, and their specific sources are shown in Table 1 below.

[0031] Table 1 Source of raw materials

[0032] Polypropylene Zhenhai Refining and Chemical E02ES zinc borate Kunshan Shengheng Chemical Erucamide Jiangsu Zhongteng ZOTN refined export grade Kaolin BASF SE product ASP200 Sodium lauryl sulfate Shanghai Yuanye Biotechnology Co., Ltd. Carbon aerogel self made coupling agent Guangzhou Zhanfei Chemical Technology KH550, KH560 1010 Lionlon, chemical name is pentaerythritol tetrakis[methyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] Irganox1330 BASF, chemical name 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene 3114 Lionlon, chemical name is 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanuric acid Irganox168 BASF, chemical name: tris(2,4-di-tert-butyl)phenyl phosphite DoverphosS-9228 American DOVER, spirophosphite type antioxidant TinuvinXT55 BASF, hindered amine light stabilizer Tinuvin770 BASF, chemical name: bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate Chimassorb 944 BASF, chemical name: poly[[6-[(1,1,3,3-tetramethylbutyl)amine]-1,3,5-triazine-2,4-diyl][(2,2,6,6-tetramethyl-4-piperidinyl)imine]-1,6-dihexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imine]]] Black masterbatch Cabot Black Masterbatch 2718

[0033] The weathering resistance of the material is determined according to PV3930, which is a test method that details the test conditions required to simulate accelerated aging in a hot and humid climate.

[0034] Examples 1-6 and Comparative Examples 1-3

[0035] According to the formula in Table 2, the carbon aerogel and the coupling agent were uniformly mixed with high-pressure stirring, and then mixed with polypropylene, a composite light and heat stabilizer, and a masterbatch in a certain proportion to obtain a mixture A. Zinc borate and erucamide were then added to obtain B. B was then injected into a reactor, and kaolin and sodium dodecyl sulfate were added. Carbon dioxide was used as a foaming agent and foamed at high temperature and high pressure to finally produce a black foamed polypropylene material with a foaming ratio of 20 times and high light aging resistance.

[0036] Table 2 Component formulations of Examples 1-6 and Comparative Example 1, wt%

[0037] Components Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Polypropylene E02ES 85.2 83.2 81.2 83.2 83.2 83.2 87.2 83.2 83.2 zinc borate 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Erucamide 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 Carbon aerogel 1 3 5 3 3 3 3 3 Coupling agent KH550 1 1 1 1 1 1 1 1 Coupling agent KH560 1 Antioxidant 1010 0.6 0.6 0.6 0.6 0.6 0.6 0.6 Antioxidant Irganox 1330 0.6 0.3 Antioxidant 3114 0.3 Spirophosphite antioxidant S-9228 0.2 Antioxidant Irganox 168 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Light stabilizer Tinuvin XT55 0.8 0.8 0.8 Light stabilizer Tinuvin 770 0.4 0.4 0.4 0.4 0.4 0.4 Light stabilizer Chimassorb 944 0.4 0.4 0.4 0.4 0.4 0.4 Cabot Black Masterbatch 2718 10 10 10 10 10 10 10 10 10 Kaolin 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Sodium lauryl sulfate 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

[0038] The modified polypropylene light stabilizers 770 and 944 for automotive parts were compounded and modified as Comparative Example 1. The pellets of Examples 1 to 6 and Comparative Examples 1 to 3 were foamed into samples and tested for weather resistance. The results are shown in Table 3.

[0039] Table 3 Accelerated aging performance of foamed polypropylene in hot and humid climate

[0040] performance Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 400h color difference change 0.27 0.23 0.27 0.23 0.29 0.23 0.78 0.27 0.21 800h color difference change 0.98 0.73 0.78 0.33 0.48 0.16 1.19 0.90 0.65 1200h color difference change 1.89 1.34 1.39 0.52 0.63 0.35 3.47 1.72 1.01

[0041] Analysis of the test results of Examples 1-6 shows that the addition of carbon aerogel improves the light aging resistance of the material, and the use of a high molecular weight and low molecular weight compounded antioxidant compounded with BASF light stabilizer XT55 has better weather resistance. Therefore, it can be seen that the addition of carbon aerogel improves the weather resistance of the material to a certain extent.

[0042] The degradation mechanism of polypropylene is primarily photooxidation, with the diffusion rate of oxygen controlling the rate of degradation. For expanded polypropylene parts, density decreases and a large number of pores appear within, forming various open or closed pores. This pore structure allows for greater oxygen ingress, leading to rapid degradation. After treatment with a coupling agent, carbon aerogel can be effectively dispersed in polypropylene resin, enhancing the adhesion between the two phases. Furthermore, due to its high specific surface area and porosity, continuous network structure, and small pore size that is interconnected with the outside world, carbon aerogel exhibits excellent absorption and release properties. During the light aging process of light-resistant foamed polypropylene materials, since antioxidants and light stabilizers are evenly dispersed in the polypropylene material, and some are adsorbed by carbon aerogels, under the influence of light-oxidative aging conditions, some antioxidants and light stabilizers are slowly released, so that the surface of the foamed polypropylene parts is not affected by oxygen and degraded. Even when the oxygen diffusion depth is greater than the epidermis thickness and enters the pore structure of the foamed polypropylene, the antioxidants and light stabilizers present in the pores of the carbon aerogel further effectively protect the tertiary carbon atoms from oxidation, thereby inhibiting the progress of the light aging reaction. In addition, some "impurities" in the foamed polypropylene, also known as "weaknesses" in photooxidative degradation, such as residual catalyst residues, large molecular peroxides, metals and other low molecular weight substances, can be adsorbed by carbon aerogels, which also reduces the degradation rate of polypropylene to a certain extent. Combined with the effective combination of antioxidants and light stabilizers, the material can fully meet the light aging requirements of 1200h, with a grayscale level of 4 or above.

Claims

1. A light-resistant foamed polypropylene material for use in black automotive exterior parts, comprising the following raw materials by weight: Polypropylene 67.6-97.1%; Zinc borate 0.01-0.2%; Erucamide 0.01-0.2%; Kaolin 0.05-1%; Sodium lauryl sulfate 0.05-1%; Carbon aerogel 1-10%; Coupling agent 0.5-5%; Composite light and heat stabilizer 0.1-5%; Black masterbatch 1-10%; The carbon aerogel is prepared by using resorcinol (R) and formaldehyde (F) as raw materials and sodium carbonate (C) as a catalyst; The coupling agent is KH550; The composite light and heat stabilizer includes a compound of antioxidant Irganox1330, antioxidant 3114, antioxidant Irganox168, and light stabilizer Tinuvin XT55; The method for preparing a light-resistant foamed polypropylene material used in black automotive exterior parts comprises the following steps: The carbon aerogel and the coupling agent are stirred at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes. After being evenly mixed, they are mixed evenly with polypropylene, a composite light and heat stabilizer, and a black masterbatch in a certain proportion at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes to obtain a mixture A. Zinc borate and erucamide are then added and mixed evenly at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes to obtain B. B is then injected into a reactor, kaolin and sodium dodecyl sulfate are added, and carbon dioxide is used as a foaming agent. The foaming is carried out at high temperature and high pressure. The temperature in the reactor is 140-160°C, the pressure in the reactor is 2-4 MPa, and the reactor is stirred by a magnetic machine at a frequency of 30-100 Hz. Finally, a black foamed polypropylene material with a foaming ratio of 20 times and high light aging resistance is obtained.

2. The light-resistant foamed polypropylene material for use in black automotive exterior parts according to claim 1, characterized in that: The polypropylene has a melt flow rate of 0.1-3 g / 10 min and is selected from high melt strength polypropylene.

3. The light-aging-resistant foamed polypropylene material for use in black automotive exterior parts according to claim 1, characterized in that: The zinc borate has a particle size of 3 to 6 μm.

4. The light-aging-resistant foamed polypropylene material for use in black automotive exterior parts according to claim 1, characterized in that: The erucamide has a purity of ≥99.9%.

5. The light-aging-resistant foamed polypropylene material used in black automotive exterior parts according to claim 1, characterized in that: The kaolin has a particle size of 0.1-50 μm.

6. The light-resistant foamed polypropylene material for use in black automotive exterior parts according to claim 1, characterized in that: The sodium lauryl sulfate has a purity of ≥97%.

7. A method for preparing a light-resistant foamed polypropylene material for use in black automotive exterior parts, characterized in that: The carbon aerogel and the coupling agent are stirred at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes. After being evenly mixed, they are mixed evenly with polypropylene, a composite light and heat stabilizer, and a black masterbatch in a certain proportion at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes to obtain a mixture A. Zinc borate and erucamide are then added and mixed evenly at a stirring speed of 100-500 rpm and a stirring time of 1-5 minutes to obtain B. B is then injected into a reactor, kaolin and sodium dodecyl sulfate are added, and carbon dioxide is used as a foaming agent. The foaming is carried out at high temperature and high pressure. The temperature in the reactor is 140-160°C, the pressure in the reactor is 2-4 MPa, and the reactor is stirred by a magnetic machine at a frequency of 30-100 Hz. Finally, a black foamed polypropylene material with a foaming ratio of 20 times and high light aging resistance is obtained.

8. Use of the light-aging-resistant foamed polypropylene material according to any one of claims 1 to 6 in black automotive exterior parts.