A PMMA / ASA composite material, its preparation method and application

Abstract

This invention relates to a PMMA / ASA composite material, its preparation method, and its applications. The PMMA / ASA composite material comprises the following components: PMMA resin, ASA resin, glass fiber, SAN resin, PC resin, and methyl methacrylate-acrylic acid copolymer. This invention effectively improves the heat resistance and gloss blackness of the PMMA / ASA composite material by combining PC resin, glass fiber, SAN resin, and a methyl methacrylate-acrylic acid copolymer with a specific weight-average molecular weight. Simultaneously, it effectively solves the problem of air marks or silver streaks easily appearing when PMMA / ASA composite materials are injection molded into large parts.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to a PMMA / ASA composite material, its preparation method, and its application. Background Technology

[0002] With the continuous development of social living standards, automobiles have become common consumer goods. However, the energy consumption generated during automobile production has become an obstacle that needs to be overcome. Therefore, paint-free high-gloss black exterior materials have emerged. These materials can be directly injection molded into parts without the need for painting, allowing them to be assembled onto the vehicle body. This significantly reduces energy consumption caused by painting and avoids solvent pollution from paints, making it an environmentally friendly solution for automotive exteriors. However, for black materials to exhibit high gloss, their gloss must be high. Simultaneously, exterior parts exposed to sunlight for extended periods must possess excellent weather resistance. To meet these two basic requirements, PMMA / ASA alloys have become the optimal solution in the current materials field. PMMA's high transparency gives the material a very high gloss, while ASA has excellent colorability, meeting aesthetic requirements. Furthermore, both PMMA and ASA exhibit extremely high photo-aging stability, allowing them to withstand long-term photo-aging tests on exterior parts.

[0003] However, the disadvantages of PMMA / ASA alloy are also obvious. First, the material has poor flowability and a narrow molding window, which can easily lead to air marks or silver streaks in the appearance when injection molding large-sized grid parts. Second, this material has low heat resistance, and the parts are prone to deformation in high-temperature environments.

[0004] The patent with publication number CN110256798A provides a PMMA / ASA alloy material. However, if too much ASA is added to this material, its heat resistance will be further reduced. Furthermore, this patent does not address the issue of poor appearance when the material is injection molded into large parts.

[0005] Therefore, there is an urgent need to develop new technologies to solve the problems of the PMMA / ASA alloy mentioned above. Summary of the Invention

[0006] The primary objective of this invention is to overcome the technical problems of the low heat deformation temperature of PMMA / ASA alloys in the current technology, and the tendency for air marks or silver streaks to appear when injection molded into large parts, and to provide a PMMA / ASA composite material.

[0007] A further object of the present invention is to provide a method for preparing the above-mentioned PMMA / ASA composite material.

[0008] A further object of the present invention is to provide the application of the above-mentioned PMMA / ASA composite material in the preparation of paint-free exterior automotive parts.

[0009] A PMMA / ASA composite material comprises the following components in parts by weight:

[0010]

[0011] The number-average molecular weight of the methyl methacrylate-acrylic acid copolymer is above 1800. The number-average molecular weight of the methyl methacrylate-acrylic acid copolymer can be determined by nuclear magnetic resonance (NMR). The determination process is as follows: 1 mg of the methyl methacrylate-acrylic acid copolymer is dissolved in deuterated chloroform, and then an NMR spectrum is obtained using 300 MHz NMR. By integrating the characteristic hydrogen peaks, the number of repeating units is calculated, and thus the number-average molecular weight is calculated.

[0012] In this invention, PMMA resin is used as the matrix resin, and it accounts for at least 25% of the mass of the PMMA / ASA composite material.

[0013] The inventors of this invention discovered through research that adding glass fiber and PC resin to PMMA / ASA alloy materials can effectively improve the heat resistance of the materials; however, the addition of glass fiber reduces the fluidity of the materials, making it easier to generate air marks or silver streaks when injection molding large parts.

[0014] Further research by the inventors revealed that adding SAN resin and a specific weight-average molecular weight methyl methacrylate-acrylic acid copolymer can effectively solve the appearance problems of air marks or silver streaks, and can also further improve heat resistance and gloss. The reasons are as follows: SAN resin can adjust the overall flowability of the material, which is beneficial for improving the formation of air marks or silver streaks when injection molding large parts; while the specific weight-average molecular weight methyl methacrylate-acrylic acid copolymer itself contains repeating units of PMMA, thus it is compatible with PMMA resin. Simultaneously, the carboxyl groups on its side chains can react and connect with the terminal hydroxyl groups of PC resin, thereby improving the compatibility of PMMA and PC resins, resulting in better overall material flowability and compatibility, effectively improving appearance problems; gloss is also improved, leading to a better gloss black after adding black pigment; in addition, due to the better material compatibility, heat resistance is further enhanced.

[0015] The weight-average molecular weight of methyl methacrylate-acrylic acid copolymers cannot be too small; otherwise, they will easily precipitate onto the surface of the material and fail to achieve good compatibility.

[0016] The present invention effectively improves the heat resistance and gloss of PMMA / ASA composite materials by combining PC resin, glass fiber, SAN resin and methyl acrylate-acrylic acid copolymer with a specific weight-average molecular weight, while effectively solving the problem of air marks or silver streaks that easily occur when PMMA / ASA composite materials are injection molded into large parts.

[0017] Typically, the melt index of the PMMA resin measured at 230°C and 3.8 kg is 1–20 g / 10 min.

[0018] Preferably, the melt index of the PMMA resin measured at 230°C and 3.8 kg is 8-16 g / 10 min. Using PMMA resin within this melt index range results in better performance of the PMMA / ASA composite material.

[0019] In this invention, the melt index of the PMMA resin can be measured according to ISO 1133-2011 standard.

[0020] In this invention, the methyl methacrylate-acrylic acid copolymer can be commercially available or prepared in-house. In-house preparation methods include solution polymerization, emulsion polymerization, or bulk polymerization. Optionally, this invention uses a bulk polymerization method to prepare the methyl methacrylate-acrylic acid copolymer. The preparation process is as follows: methyl methacrylate and acrylic acid are mixed, and then an initiator is added under stirring. The mixture is reacted for 4-6 hours under an inert atmosphere and at 40-80°C to obtain the methyl methacrylate-acrylic acid copolymer. The molar ratio of methyl methacrylate to acrylic acid is (1.1-1.5):1.

[0021] Optionally, the number average molecular weight of the methyl methacrylate-acrylic acid copolymer is 1800 to 5000, specifically 1800, 2000, 2200, 2400, 2500, 2800, 3000, 3200, 3500, 3800, 4000, 4200, 4500, 4800 or 5000.

[0022] Preferably, the number average molecular weight of the methyl methacrylate-acrylic acid copolymer is 3000 to 5000. Selecting methyl methacrylate-acrylic acid copolymers within this number average molecular weight range results in a better appearance.

[0023] Typically, the melt index of the ASA resin measured at 220°C and 10 kg is 10–15 g / 10 min.

[0024] In this invention, the melt index of the ASA resin can be measured according to the ISO 1183-2011 standard.

[0025] Typically, the glass fiber has a circular cross-section with a diameter of 10–13 μm.

[0026] Typically, the melt flow index of the SAN resin measured at 200°C and 5 kg is 10–65 g / 10 min.

[0027] Preferably, the melt flow index of the SAN resin measured at 200°C and 5 kg is 19-40 g / 10 min. SAN resins within this molecular weight range are selected to obtain PMMA / ASA composite materials with better properties.

[0028] In this invention, the melt flow index of the SAN resin can be measured according to ISO 1183-2011 standard.

[0029] Typically, the melt index of the PC resin measured at 300°C and 1.2 kg is 45–75 g / 10 min.

[0030] Preferably, the melt index of the PC resin measured at 300°C and 1.2 kg is 50-60 g / 10 min. Selecting PC resin within this molecular weight range will result in a higher gloss of the PMMA / ASA composite material.

[0031] In this invention, the melt index of the PC resin can be measured according to ISO 1183-2011 standard.

[0032] Typically, the PMMA / ASA composite material also includes 0.5 to 1 part by weight of colorant.

[0033] Typically, the pigment is a black pigment, including inorganic black pigment and / or organic black pigment; inorganic black pigment includes, but is not limited to, carbon black, and organic black pigment includes, but is not limited to, aniline black, perylene black, or ink black.

[0034] Optionally, the other additives are at least one of lubricant, antioxidant, or weathering agent.

[0035] Optionally, the lubricant is at least one of polyethylene, silicone, or stearate.

[0036] Optionally, the antioxidant is at least one of pentaerythritol ester or n-octadecyl propionate.

[0037] Optionally, the weathering agent is at least one of bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate or 2-(2'-hydroxy-3',5'-dicumylphenyl)benzotriazole.

[0038] The preparation method of the above-mentioned PMMA / ASA composite material includes the following steps: mixing the components, melt extruding, and granulating to obtain the PMMA / ASA composite material.

[0039] Preferably, the melt extrusion is carried out in a twin-screw extruder, and the temperature of the melt extrusion is 230-260°C; the main engine speed of the twin-screw extruder is 450-550 rpm, and the length-to-diameter ratio of the screw is 50-70:1.

[0040] The application of the aforementioned PMMA / ASA composite material in the preparation of paint-free automotive exterior parts is also within the scope of protection of this invention.

[0041] Preferably, the paint-free exterior parts for vehicles are rearview mirror housings, B-pillar trim panels, or D-pillar triangular windows.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] The present invention effectively improves the heat resistance and gloss of PMMA / ASA composite materials by combining PC resin, glass fiber, SAN resin and methyl acrylate-acrylic acid copolymer with a specific weight-average molecular weight, while effectively solving the problem of air marks or silver streaks that easily occur when PMMA / ASA composite materials are injection molded into large parts. Detailed Implementation

[0044] To more clearly and completely describe the technical solution of the present invention, the present invention will be further described in detail below through specific embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention. Various changes can be made within the scope of the claims of the present invention.

[0045] The reagents used in the various embodiments and comparative examples of this invention are described below:

[0046] PMMA resin #1: Chimei, CM-211, melt index is 16g / 10min;

[0047] PMMA resin #2: Chimei, CM-207, melt flow index is 8g / 10min;

[0048] PMMA resin #3: Chi Mei, CM-205, melt flow index is 2g / 10min;

[0049] ASA resin #1: Anqiu Donghai Plastics Co., Ltd., Q350, melt index is 12g / 10min;

[0050] ASA resin #2: Anqiu Donghai Plastics Co., Ltd., Q500, melt index is 14g / 10min;

[0051] Fiberglass 1#: Megalith, ECS13-4.5-534A, circular cross-section, 13μm in diameter;

[0052] Fiberglass No. 2: Megalith, ECS10-4.5-534A, circular cross-section, 10μm in diameter;

[0053] SAN Resin 1#: Jia Yi Rong, EMI-200, melt index is 65g / 10min;

[0054] SAN resin #2: Chi Mei, D-178HF, melt flow index is 19 g / 10 min;

[0055] SAN resin #3: Kumho Petrochemical, SAN 320NA, melt flow index is 11g / 10min;

[0056] PC resin #1: Ningbo Dopod Polymer Co., Ltd., T60A, melt index is 50g / 10min;

[0057] PC resin #2: Wanhua Chemical, PC 2600, melt index is 60g / 10min;

[0058] PC resin #3: Shanghai Aosaier Materials Technology Co., Ltd., ASL-60A, melt flow index is 70g / 10min;

[0059] Methyl methacrylate-acrylic acid copolymer 1#: Prepared in-house, the preparation method is as follows: Take 5 mol of methyl methacrylate and 4.2 mol of acrylic acid, and mix them uniformly for 30 minutes under mechanical stirring. Then, add 10 ml of AIBN dropwise to the system, and continue stirring while purging with nitrogen. React at 80°C for 6 hours. Slowly pour the mixture into ethanol while stirring. The polymerization product, being insoluble in ethanol, will precipitate as a solid in the ethanol solution. Filter and collect the solid to obtain methyl methacrylate-acrylic acid copolymer 1#, denoted as PMMA-COOH1#. The number average molecular weight of PMMA-COOH1# is tested to be 5000 g / mol.

[0060] Methyl methacrylate-acrylic acid copolymer 2#: Prepared in-house, the preparation method is basically the same as that of methyl methacrylate-acrylic acid copolymer 1#, except that the reaction temperature is 60℃, yielding methyl methacrylate-acrylic acid copolymer 2#, denoted as PMMA-COOH2#. The number average molecular weight of PMMA-COOH2# is tested to be 3000 g / mol.

[0061] Methyl methacrylate-acrylic acid copolymer 3#: Prepared in-house, the preparation method is basically the same as that of methyl methacrylate-acrylic acid copolymer 1#, except that the reaction temperature is 40℃, thus obtaining methyl methacrylate-acrylic acid copolymer 3#, denoted as PMMA-COOH3#. The number average molecular weight of PMMA-COOH3# is tested to be 2000 g / mol.

[0062] Methyl methacrylate-acrylic acid copolymer 4#: Prepared in-house, the preparation method is basically the same as that of methyl methacrylate-acrylic acid copolymer 1#, except that the reaction temperature is reduced to 40℃ and the reaction time is 2 hours, thus obtaining methyl methacrylate-acrylic acid copolymer 4#, denoted as PMMA-COOH4#. The number average molecular weight of PMMA-COOH4# is tested to be 900 g / mol.

[0063] Pigment: Acetylene black, Denka black, Denka Singapore Private Limited;

[0064] Other additives: Lubricant, PETS-AP, commercially available.

[0065] Unless otherwise specified, all components (e.g., other additives) used in each parallel embodiment and comparative example are the same commercially available products.

[0066] The performance of the PMMA / ASA composite materials provided in the embodiments and comparative examples of this invention was determined according to the following test methods:

[0067] Heat resistance test: The PMMA / ASA composite materials of each example and comparative example were injection molded into ISO bending specimens, and their Vicat softening temperature was tested according to ISO 75B50 standard.

[0068] Large Injection Molded Part Appearance Test: Each PMMA / ASA composite material was injection molded into a part with dimensions of approximately 505*170*40mm and a wall thickness of approximately 2.5mm. The surface of the part was observed for silver streaks or air bubbles, and rated according to the following standards:

[0069] Level 5: Area with silver streaks or air bubbles > 15mm 2 ;

[0070] Level 4: The area with silver streaks or air marks is 10 < S ≤ 15 mm 2 ;

[0071] Level 3: The area with silver streaks or air marks is 5 < S ≤ 10 mm 2 ;

[0072] Level 2: The area with silver streaks or air marks is 0 < S ≤ 5 mm 2 ,

[0073] Level 1: No silver streaks or air bubbles appear;

[0074] Generally, when the appearance test level is 1 to 3, the appearance of PMMA / ASA composite material is considered acceptable, and it can effectively avoid silver streaks or air marks when used for injection molding into automotive parts; if the appearance test level is 4 or 5, it is considered unacceptable.

[0075] Gloss level: The injection-molded 80*40*2mm square plate is tested for gloss level using a gloss meter. The higher the gloss level, the higher the gloss level.

[0076] The PMMA / ASA composite materials of the embodiments and comparative examples of the present invention were prepared by the following preparation method:

[0077] The components of the formula were weighed and mixed evenly in a high-speed mixer at 1500 rpm. The mixture was then fed into a twin-screw extruder for melt extrusion and granulation to obtain the PMMA / ASA composite material. The temperatures of each zone of the twin-screw extruder were sequentially controlled at 160℃, 230℃, 230℃, 240℃, 240℃, 250℃, 250℃, 240℃, and 240℃, with the main extruder speed at 500 rpm and the screw length-to-diameter ratio at 60:1.

[0078] Examples 1-13

[0079] Examples 1-13 provide a series of PMMA / ASA composite materials, the formulations of which are shown in Tables 1 and 2.

[0080] Table 1. Formulations (parts by weight) for Examples 1-6

[0081]

[0082] Table 2. Formulations (parts by weight) for Examples 7-13

[0083]

[0084]

[0085] Comparative Examples 1-5

[0086] Comparative Examples 1–5 provide a series of PMMA / ASA composite materials, the formulations of which are shown in Table 3.

[0087] Table 3 shows the formulations (parts by weight) for Comparative Examples 1–5.

[0088]

[0089] The properties of the PMMA / ASA composite materials of each embodiment and comparative example were determined according to the test methods mentioned above, and the test results are shown in Table 4.

[0090] Table 4. Performance test results of PMMA / ASA composite materials in each example and comparative example.

[0091]

[0092]

[0093] As can be seen from Table 4:

[0094] The Vicat softening temperature of the PMMA / ASA composite materials in Examples 1 to 13 is above 114°C, the appearance of the injection-molded large parts is above grade 3, and the gloss is above 80. This shows that the PMMA / ASA composite material of the present invention has good heat resistance, high gloss blackness, and effectively solves the problem of air marks or silver streaks that are easy to occur when injection molding large parts.

[0095] Comparative Example 1, without glass fiber, showed poor heat resistance in the PMMA / ASA composite material. Comparative Example 2, without SAN resin, showed poor appearance and low gloss blackness in large injection-molded PMMA / ASA composite materials. Comparative Example 3, without PC resin, showed poor heat resistance in the PMMA / ASA composite material. Comparative Example 4, without methyl methacrylate-acrylic acid copolymer, showed poor appearance, low gloss blackness, and poor heat resistance in large injection-molded PMMA / ASA composite materials. Comparative Example 5, with an unsuitable molecular weight of methyl methacrylate-acrylic acid copolymer, also showed poor appearance and low gloss blackness in large injection-molded PMMA / ASA composite materials.

[0096] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A PMMA / ASA composite material, characterized in that, The components include the following parts by weight: 40-60 parts of PMMA resin 20-30 parts of ASA resin, 5-15 parts glass fiber, 5-15 parts of SAN resin, 5-15 parts of PC resin, 5-15 parts of methyl methacrylate-acrylic acid copolymer Other auxiliary agents: 1-5 parts; The number average molecular weight of the methyl methacrylate-acrylic acid copolymer is 1800~5000.

2. The PMMA / ASA composite material according to claim 1, characterized in that, The melt flow index of the PMMA resin measured at 230°C and 3.8 kg was 1~20 g / 10 min.

3. The PMMA / ASA composite material according to claim 1, characterized in that, The number average molecular weight of the methyl methacrylate-acrylic acid copolymer is 2000~5000.

4. The PMMA / ASA composite material according to claim 1, characterized in that, The melt flow index of the ASA resin measured at 220℃ and 10kg was 12~15g / 10min.

5. The PMMA / ASA composite material according to claim 1, characterized in that, The glass fiber has a circular cross-section with a diameter of 10~13μm.

6. The PMMA / ASA composite material according to claim 1, characterized in that, The melt flow index of the SAN resin measured at 200°C and 5 kg was 10~65 g / 10min.

7. The PMMA / ASA composite material according to claim 1, characterized in that, The melt flow index of the PC resin measured at 300℃ and 1.2kg was 45~75 g / 10min.

8. The PMMA / ASA composite material according to claim 1, characterized in that, The other additives are at least one of lubricants, antioxidants, or weather-resistant agents.

9. A method for preparing the PMMA / ASA composite material according to any one of claims 1 to 8, characterized in that, The process includes the following steps: mixing the components and melt-extruding to obtain the PMMA / ASA composite material.

10. The use of the PMMA / ASA composite material according to any one of claims 1 to 8 in the preparation of paint-free exterior automotive parts.

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