High-weather-resistance talcum powder filled spraying-free polypropylene composite material as well as preparation method and application thereof

Abstract

The invention discloses a high-weather-resistance talcum powder filled spraying-free polypropylene composite material as well as a preparation method and application thereof. According to the material, an innovative solution is provided for solving the problem of synergistic interface catalytic aging caused by talcum powder and aluminum powder in a polypropylene system. The material is prepared from the following components in parts by weight: 50 to 75 parts of polypropylene resin, 10 to 25 parts of talcum powder, 1 to 4 parts of high-weather-resistance coated aluminum powder, 0.5 to 3 parts of a UV screening agent, 0.5 to 2.5 parts of a UV absorbent, 0.3 to 1.5 parts of a metal passivation type antioxidant and 3 to 8 parts of a compatilizer. The specific metal deactivator is introduced into the system for the first time, and the problem of interface catalytic aging is successfully solved through the synergistic effect of the metal deactivator and the UV stabilizer and an optimized two-step master batch process. After the material is aged for 4000 hours according to the PV3930 standard, the color difference delta E is smaller than 2.0, the gray level reaches level 4 or above, and the material has excellent rigidity, toughness and metal appearance and is particularly suitable for high-end automobile exterior trimming parts with strict requirements for rigidity and weather resistance.

Description

Technical Field

[0001] This invention belongs to the field of polymer material modification technology, specifically relating to a talc-filled, spray-free polypropylene composite material with ultra-weather resistance and its preparation method. Background Technology

[0002] Polypropylene (PP) is widely used in automotive parts due to its low cost, low density, and good overall performance. To improve its rigidity and heat resistance, talc is often added. To achieve a high-end metallic appearance and reduce VOC emissions, paint-free technology has been introduced.

[0003] However, combining high-content talc, metallic effect pigments, and long-lasting weather resistance presents significant technical bottlenecks. Conventional talc-filled, spray-free PP materials typically employ a stabilization system using ultraviolet absorbers (UVA) and hindered amine light stabilizers (HALS). However, the applicant's research has found that in complex systems with numerous filler-resin interfaces, the stabilizing effect of HALS is significantly reduced due to adsorption and interactions on the filler surface.

[0004] Those skilled in the art will recognize that metal passivators, as a class of functional additives, are commonly used to prevent catalytic aging of polymers when in contact with specific metals. For example, they are used in cable materials to prevent the catalytic effect of copper conductors, or in recycled plastics to stabilize metal impurities. However, the use of metal passivators to address the interfacial synergistic catalytic aging problem caused by trace metal impurities in the filler and effect pigments in paint-free polypropylene systems containing a high proportion of talc and aluminum pigments has not been publicly reported.

[0005] Current technologies generally overlook the trace metal impurities (such as Fe) carried in talc. 3+ The "interfacial catalytic center" formed by the polypropylene matrix and aluminum pigment under ultraviolet light will significantly accelerate the photo-oxidative aging of the polypropylene matrix. This is one of the fundamental reasons why conventional materials experience a sharp decline in performance (color difference ΔE>3.0, severe pulverization) in ultra-long aging tests such as PV3930.

[0006] Therefore, developing a talc-filled, spray-free PP material that can fundamentally inhibit this interfacial synergistic catalytic aging while meeting the requirements of high rigidity, excellent metallic appearance, and ultra-weather resistance is a technical challenge that urgently needs to be overcome in this field. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high-weather-resistant talc-filled, spray-free polypropylene composite material and its preparation method. This material, through a unique stabilization system and preparation process, effectively solves the problem of synergistic interfacial catalytic aging caused by talc and aluminum powder. Another objective of this invention is to provide a method for preparing the above-mentioned material.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A high weather-resistant talc-filled, spray-free polypropylene composite material, comprising the following components by weight:

[0010] Polypropylene matrix resin: 50-75 parts;

[0011] Talc powder: 10-25 parts;

[0012] High weather-resistant coated aluminum powder: 1-4 parts;

[0013] UV shielding agent: 0.5-3 parts;

[0014] UV absorber: 0.5-2.5 parts;

[0015] Metal passivation antioxidant: 0.3-1.5 parts;

[0016] Compatibilizer: 3-8 parts;

[0017] Preferably, the polypropylene matrix resin is an impact-resistant copolymer polypropylene with a melt flow rate (230℃ / 2.16kg) of 15-30g / 10min.

[0018] Preferably, the talc powder is a high aspect ratio flake talc powder that has been surface-treated with a silane coupling agent, and the median diameter D50 is 2-5 μm.

[0019] Preferably, the high weather-resistant coated aluminum powder is flake-shaped aluminum powder coated with silica, with a median diameter D50 of 20-40 μm.

[0020] Preferably, the UV shielding agent is nano-sized rutile titanium dioxide or zinc oxide. The UV absorber is a high molecular weight benzotriazole or triazine UV absorber.

[0021] Preferably, the metal passivating antioxidant is a hydrazine-based or triazole-based metal passivating agent. Its core function is to simultaneously passivate the metal impurities in talc powder and the surface of aluminum pigments, thereby inhibiting interfacial catalytic effects at the source.

[0022] Preferably, the compatibilizer is maleic anhydride-grafted polypropylene.

[0023] The method for preparing the composite material of the present invention includes the following steps:

[0024] 1. Preparation of talc masterbatch: All talc powder, a portion of polypropylene matrix resin, all compatibilizer, and all metal passivating antioxidants in the formula are melt-blended and granulated. This step achieves precise pre-protection of the main catalyst source (talc powder).

[0025] 2. Preparation of effect pigment masterbatch: All the high weather-resistant coated aluminum powder, UV shielding agent, UV absorber, and part of the polypropylene matrix resin in the formula are melt-blended, with the processing temperature strictly controlled at 200-220℃, followed by granulation. This low-temperature process is crucial for protecting the morphology of the aluminum powder and the integrity of the coating layer.

[0026] 3. Final mixing and granulation: The remaining polypropylene matrix resin, the above-mentioned talc masterbatch and effect pigment masterbatch are melt-blended and extruded into granules.

[0027] Compared with the prior art, the present invention has the following significant advantages:

[0028] 1. Innovation in problem discovery and solution: This invention is the first to clearly reveal the hidden problem of "synergistic interfacial catalytic aging" in the talc / aluminum / PP composite system, and creatively introduces metal passivation antioxidants as a solution.

[0029] 2. Synergy and non-obviousness of the technical solution: The synergistic stabilization system composed of metal passivators, UV shielding agents, and UV absorbers, combined with a two-step masterbatch process designed specifically for it, forms a complete and efficient technical solution.

[0030] 3. Significance and Verifiability of Technical Effects: As shown in the following examples, after 4000 hours of extreme aging according to the PV3930 standard, the material of this invention exhibits a stable color difference ΔE of less than 2.0 and a grayscale level of 4, far exceeding the performance of traditional systems. Detailed Implementation

[0031] The present invention will be further illustrated by the following examples.

[0032] Examples 1-3 and Comparative Example 1 prepared composite materials according to the formulations (parts by weight) shown in Table 1 below.

[0033] Table 1. Formulations of Examples and Comparative Examples (parts by weight)

[0034]

[0035]

[0036] Preparation method:

[0037] Examples 1-2: The process was carried out according to the two-step masterbatch process of the present invention.

[0038] Comparative Example 1: Using the traditional HALS system and one-step process.

[0039] Comparative Example 2: The process of this invention was used, but without the metal passivating agent. The process was carried out according to the aforementioned two-step masterbatch process.

[0040] Performance Tests and Results

[0041] The resulting granules were injection molded into standard test strips and color swatches.

[0042] 1. Initial performance: Test flexural modulus.

[0043] 2. Weather resistance test: Xenon lamp aging test for 4000 hours according to PV3930 standard, and color difference (ΔE) and gray level are measured after the test.

[0044] Test Project Example 1 Example 2 Comparative Example 1 Comparative Example 2 Initial performance Flexural modulus (MPa) 2200 2800 2700 2180 Color difference ΔE after PV39304000h 1.6 1.3 5.2 3.9 Gray levels 4 4 2 3 Surface condition intact intact Severe pulverization Noticeable powdering

[0045] Results analysis:

[0046] Table 2 shows that the embodiments of the present invention exhibit excellent weather resistance after 4000 hours of aging under the PV3930 standard. Comparative Example 1 (traditional system) showed severe performance degradation, proving that the traditional approach cannot solve the aging problem of this system. Comparative Example 2 (without metal passivator) showed significantly better performance than Comparative Example 1 but significantly worse performance than Example 1, strongly demonstrating the crucial role of the metal passivator in this system: it produced a synergistic effect with other components, jointly solving the interfacial catalytic aging problem.

[0047] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high weather-resistant talc-filled, spray-free polypropylene composite material, characterized in that, Based on parts by weight, it comprises the following components: Polypropylene matrix resin: 50-75 parts; Talc powder: 10-25 parts; High weather-resistant coated aluminum powder: 1-4 parts; UV shielding agent: 0.5-3 parts; UV absorber: 0.5-2.5 parts; Metal passivation antioxidant: 0.3-1.5 parts; Compatibilizer: 3-8 parts.

2. The high weather-resistant talc-filled, spray-free polypropylene composite material according to claim 1, characterized in that, The talc powder is a high aspect ratio flake talc powder with a median diameter (D50) of 2-5 μm, which has been surface-treated with a silane coupling agent.

3. The high weather-resistant talc-filled, spray-free polypropylene composite material according to claim 1, characterized in that, The high weather-resistant coated aluminum powder is a sheet-like aluminum powder that has undergone dense coating treatment with silica, and the median diameter D50 is 20-40 μm.

4. The high weather-resistant talc-filled, spray-free polypropylene composite material according to claim 1, characterized in that, The UV shielding agent is nano-titanium dioxide or nano-zinc oxide; the UV absorber is a benzotriazole or triazine UV absorber.

5. The high weather-resistant talc-filled, spray-free polypropylene composite material according to claim 1, characterized in that, The metal passivating antioxidant is a hydrazine-based or triazole-based metal passivating agent.

6. The high weather-resistant talc-filled, spray-free polypropylene composite material according to claim 1, characterized in that, The compatibilizer is maleic anhydride-grafted polypropylene.

7. A method for preparing a high weather-resistant talc-filled, spray-free polypropylene composite material as described in any one of claims 1-6, characterized in that, Includes the following steps: a) Preparation of talc masterbatch: Talc masterbatch is prepared by melt-blending the talc powder, a portion of the polypropylene resin, all of the compatibilizer and all of the metal passivation antioxidant. b) Preparation of effect pigment masterbatch: The high weather-resistant coated aluminum powder, the UV shielding agent, the UV absorber and a portion of the polypropylene resin are melt-blended to obtain effect pigment masterbatch; c) Final mixing and granulation: The remaining polypropylene matrix resin, the talc masterbatch obtained in step a), and the effect pigment masterbatch obtained in step b) are melt-blended and extruded into granules.

8. The high weather-resistant talc-filled, spray-free polypropylene composite material according to claim 7, characterized in that, In step b), the processing temperature of the effect pigment masterbatch is controlled at 200-220℃.

9. The use of a composite material as described in any one of claims 1-6 in the manufacture of automotive exterior parts.

10. The application according to claim 9, characterized in that, The automotive exterior components are bumper trim strips and upper and lower bumper guards.

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