A polypropylene material and its preparation method

Abstract

The present invention relates to a polypropylene material and a preparation method thereof, comprising a polypropylene resin, an inorganic microporous filler and a compatibilizer. The compatibilizer adopted in the present invention has good interfacial affinity with the inorganic microporous filler, a high degree of internal stress dispersion, and good mechanical properties of the product; at the same time, due to the presence of polar groups in the grafted layer of the three-dimensional structure in the polypropylene material after reactive extrusion, it has an obvious effect on improving the bonding strength between the substrate and the coating after electroplating.

Description

Technical Field

[0001] The present invention belongs to the field of modified plastics, and particularly relates to a polypropylene material and a preparation method thereof. Background Art

[0002] Electroplated plastics have excellent scratch resistance and antistatic properties. Compared with spray-free materials, they have higher gloss and metallic texture, and have the characteristics of low density and low cost, making them ideal materials to replace metals and spray-free plastics. However, electroplated plastics currently mainly use materials such as ABS, ASA, and PVC. These materials have higher costs and can produce volatile organic compounds harmful to the human body. The PP material usually has a too smooth surface, few surface grafted functional groups, low surface energy, and low metal adhesion, making it difficult to electroplate, and the stability after electroplating is also poor, which limits its development in the electroplating field.

[0003] Patent CN201711161471 discloses a polypropylene composite material suitable for electroplating reaction and a preparation method thereof. Using a calcium carbonate and barium sulfate compound system as the acidification treatment point, the conventional inorganic filling system has a larger particle size or uneven dispersion. After surface roughening, it is rough and uneven, and pits above 10 microns are likely to appear, affecting the smoothness of the electroplated surface. In addition, the density of the pores and the particle size after roughening will also affect the peeling strength of the electroplated layer. Therefore, electroplated polypropylene with a conventional inorganic filling as the acidification treatment point is difficult to be applied to actual parts. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a polypropylene material and a preparation method thereof, which have an obvious effect on improving the bonding force between the substrate and the coating after electroplating.

[0005] The present invention provides a polypropylene material, which comprises the following components by mass:

[0006] 45 - 75 parts of polypropylene resin;

[0007] 20 - 40 parts of inorganic microporous filler;

[0008] 5 - 15 parts of compatibilizer; Among them, the compatibilizer is a trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer.

[0009] The polypropylene resin is at least one of homopolypropylene and copolymerized polypropylene.

[0010] The average particle size of the inorganic microporous filler is 0.05 - 10 μm. Preferably, the average particle size of the inorganic microporous filler is 0.05 - 3 μm, and calcium silicate filler is preferred.

[0011] The average particle size is large or unevenly dispersed, and the surface is rough and uneven after coarsening, and pits larger than 10 microns are likely to appear, affecting the smoothness of the electroplated surface. In addition, the density of the pores and the particle size after coarsening will also affect the peeling strength of the electroplated layer.

[0012] The trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer comprises the following components: polyolefin thermoplastic elastomer, trimethylolpropane triacrylate TMPTA, styrene St; the mass ratio is (2000-2500):(60-80):(60-80); the grafting rate of the trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer is 8-18%. Preferably, the grafting rate of the trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer is 10-15%.

[0013] Grafting rate determination method: Use Heracus-CHNOS element analyzer to measure the oxygen percentage of the compatibilizer, and use the formula to calculate the grafting rate M: P = (N1 / N2) × oxygen percentage; M = P / (100-P). Where N1 is the molecular weight of the active monomer, and N2 is the molecular weight of oxygen.

[0014] The reason why a modified grafted polyolefin thermoplastic elastomer with a grafting rate of 10-15% is preferred as a compatibilizer is that when the grafting rate is less than 10%, the proportion of polar groups in the compatibilizer is small, and the compatibility and mechanical properties of the PP material cannot be effectively improved. When the grafting rate is greater than 15%, the reaction time needs to be increased in the production process of the modified grafted polyolefin thermoplastic elastomer, resulting in more side reactions and serious internal cross-linking, thereby affecting the activity of the reaction between the compatibilizer and the PP material.

[0015] The polyolefin thermoplastic elastomer is at least one of ethylene-octene copolymer and ethylene-butene copolymer.

[0016] Preferably, the following components are included by weight:

[0017] Polypropylene resin 50-65 parts;

[0018] 30-35 parts of inorganic microporous filler;

[0019] Compatibilizer 6-10 parts.

[0020] The present invention provides a method for preparing a polypropylene material, comprising the following steps:

[0021] (1) The polyolefin thermoplastic elastomer is mixed evenly with trimethylolpropane triacrylate (TMPTA), St, and DCP in a container according to the mass ratio of (2000 - 2500):(60 - 80):(60 - 80):(10 - 20). Then, it is added to a twin-screw extruder for melt grafting reaction. The extruded spline is air-cooled and pelletized to obtain trimethylolpropane triacrylate (TMPTA) grafted polyolefin thermoplastic elastomer;

[0022] (2) Using the trimethylolpropane triacrylate (TMPTA) grafted polyolefin thermoplastic elastomer as a compatibilizer, polypropylene resin and inorganic microporous filler are added in proportion and mixed in a high-speed mixer to obtain a premix. The premix is added to the main feeding port of a twin-screw extruder for melt extrusion, pelletizing, and drying to obtain the high-performance excellent electroplating-grade polypropylene material.

[0023] The present invention provides an application of a polypropylene material in electroplating-grade modified materials, especially in automotive electroplated ornaments such as air outlet trims and grilles.

[0024] After graft modification, the compatibilizer in the present invention has good interfacial affinity with the inorganic microporous filler. As a multi-functional monomer, when TMPTA undergoes graft polymerization with the polyolefin thermoplastic elastomer, more double bonds will become initiation growth points, and the graft chains are prone to form a cross-linked structure, forming a graft layer with a three-dimensional structure on the surface. Due to good interfacial affinity and high internal stress dispersion, the mechanical properties of the product are good; at the same time, due to the presence of polar groups in the three-dimensional structure graft layer of the polypropylene composite material after reactive extrusion, it has an obvious effect on improving the bonding strength between the electroplated substrate and the plating layer.

[0025] The surface of the inorganic microporous filler in the present invention has a rich nano-scale microporous structure. During application, a microporous structure of about 0.2 - 2 μm can be formed on the surface of the polypropylene resin, and these appropriately sized microporous structures have the strongest anchoring force for metal particles during electroplating. Moreover, this obvious difference in the effective pore diameter of different roughened surfaces in terms of quantity leads to different mechanical anchoring forces, which ultimately affects the peel strength between the modified polypropylene and the metal plating layer.

[0026] Beneficial effects

[0027] The compatibilizer adopted in the present invention has good interfacial affinity with calcium silicate and high internal stress dispersion, and the mechanical properties of the product are good; at the same time, due to the presence of polar groups in the three-dimensional structure graft layer of the polypropylene material after reactive extrusion, it has an obvious effect on improving the bonding strength between the electroplated substrate and the plating layer. Detailed implementation mode

[0028] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0029] PP1: PP EP548R, copolymerized polypropylene, purchased from Shell;

[0030] PP2: PPH-MN150, homopolymerized polypropylene, purchased from Luoyang Branch of Sinopec;

[0031] Calcium silicate 1: average particle size of 1 μm, purchased from Shanxi Yuzhu New Materials;

[0032] Calcium silicate 2: average particle size of 2 μm, purchased from Shanxi Yuzhu New Materials;

[0033] Calcium silicate 3: average particle size of 10 μm, purchased from Shanxi Yuzhu New Materials;

[0034] Calcium carbonate: average particle size of 3 μm, commercially available;

[0035] Talc powder: average particle size of 3 μm, commercially available;

[0036] Compatibilizer 1: modified grafted polyolefin thermoplastic elastomer 1;

[0037] The preparation method includes: mixing ethylene-octene copolymer with trimethylolpropane triacrylate TMPTA and St in a container according to a mass ratio of 2000:60:60, and then using DCP with a mass ratio of 10:2000 to the ethylene-octene copolymer as an initiator, adding it to a twin-screw extruder for melt grafting reaction. The extruded spline is cooled by air and granulated to obtain a modified grafted ethylene-octene copolymer with a grafting rate of 10%. The temperatures of each section of the extruder are 170, 170, 180, 180, 180, 200, 200 °C. The screw speed is 70 r / min.

[0038] Compatibilizer 2: modified grafted polyolefin thermoplastic elastomer 2;

[0039] The preparation method includes: uniformly mixing ethylene-butene copolymer with trimethylolpropane triacrylate (TMPTA) and St in a container according to a mass ratio of 2500:80:80. Then, using DCP with a mass ratio of 20:2500 to the ethylene-butene copolymer as an initiator, adding it to a twin-screw extruder for melt grafting reaction. The extruded spline is air-cooled and pelletized to obtain a modified grafted ethylene-butene copolymer with a grafting rate of 15%. The temperatures of each section of the extruder are 170, 170, 180, 180, 180, 200, 200 °C. The screw speed is 70 r / min.

[0040] Compatibilizer 3: Modified grafted polyolefin thermoplastic elastomer 3;

[0041] The preparation method includes: uniformly mixing ethylene-butene copolymer with trimethylolpropane triacrylate (TMPTA) and St in a container according to a mass ratio of 2000:60:60. Then, using DCP with a mass ratio of 10:2000 to the ethylene-butene copolymer as an initiator, adding it to a twin-screw extruder for melt grafting reaction. The extruded spline is air-cooled and pelletized to obtain a modified grafted ethylene-butene copolymer with a grafting rate of 8%. The temperatures of each section of the extruder are 170, 170, 180, 180, 180, 180, 180 °C. The screw speed is 60 r / min.

[0042] Compatibilizer 4: Modified grafted polyolefin thermoplastic elastomer 4;

[0043] The preparation method includes: uniformly mixing ethylene-butene copolymer with trimethylolpropane triacrylate (TMPTA) and St in a container according to a mass ratio of 2500:80:80. Then, using DCP with a mass ratio of 20:2500 to the ethylene-butene copolymer as an initiator, adding it to a twin-screw extruder for melt grafting reaction. The extruded spline is air-cooled and pelletized to obtain a modified grafted ethylene-butene copolymer with a grafting rate of 18%. The temperatures of each section of the extruder are 170, 170, 180, 180, 180, 220, 220 °C. The screw speed is 80 r / min.

[0044] Compatibilizer 5: PP-g-MAH, CMG9801, grafting rate 0.5 - 1% by acid-base titration method, Jiayirong Compatibilizer Jiangsu Co., Ltd.

[0045] Compatibilizer 6: Polypropylene grafted GMA (PP-g-GMA), SPG-01, grafting rate 2 - 3% by acid-base titration method, Jiayirong Compatibilizer Jiangsu Co., Ltd.

[0046] Compatibilizer 7: Polyolefin elastomer grafted GMA (POE-g-GMA), SOG-03, grafting rate 2 - 3% by acid-base titration method, Jiayirong Compatibilizer Jiangsu Co., Ltd.

[0047] The composite materials of each example and comparative example were prepared through the following process:

[0048] Using the compatibilizers 1-7 as compatibilizers, adding polypropylene resin and inorganic fillers such as calcium silicate, calcium carbonate or talc in proportion, mixing in a high-speed mixer for 1-3 min to obtain a premix; adding the premix to the main feeding port of a twin-screw extruder, performing melt extrusion, pelletizing and drying to obtain the high-performance excellent electroplating grade polypropylene material.

[0049] The conditions of the melt extrusion step are as follows: the temperature of the first zone is 140-180 °C, the temperature of the second zone is 220-240 °C, the temperature of the third zone is 230-270 °C, the temperature of the fourth zone is 230-270 °C, the temperature of the fifth zone is 230-270 °C, the temperature of the sixth zone is 230-270 °C, the temperature of the seventh zone is 230-270 °C, the temperature of the eighth zone is 230-270 °C, the temperature of the ninth zone is 230-270 °C, and the main machine speed is 250-600 revolutions per minute; the length-diameter ratio of the twin-screw extruder is 40:1.

[0050] The examples and comparative examples were tested by the following test methods or test standards:

[0051] ① The cantilever beam notched impact test of the material was carried out with reference to ISO 179-1 / 1eA-2010, and the flexural modulus test of the material was carried out with reference to ISO 178-2010, with a speed of 2 mm / min.

[0052] ② The surface gloss after electroplating was evaluated by visual inspection of the gloss of the coating, and the strength of the reflectivity of the coating surface was observed as the basis.

[0053] The brightness was divided into grades, and a brightness of 1 was better. The grading reference standard for the visual gloss experience evaluation method is as follows.

[0054] Grade 1 (mirror bright): The coating surface is as bright as a mirror, and the facial features and eyebrows can be clearly seen.

[0055] Grade 2 (bright): The coating surface is bright, and the facial features and eyebrows can be seen, but the eyebrows are blurred.

[0056] Grade 3 (semi-bright): The coating surface has a slight brightness, and only the outline of the facial features can be seen.

[0057] Grade 4 (no brightness): The coating is basically without gloss, and the outline of the facial features cannot be seen.

[0058] ③ The test method for the peeling strength of the electroplated layer (high-pressure water flushing method) is to test the high-pressure water flushing resistance experiment according to the ISO 16925 standard. The test conditions are: water temperature 40°C, spraying time 20S, water flow rate 8L / min, spraying distance 130mm. Compared with the DIN55662 standard image, it is graded from 0 to 5 levels, with level 0 being the best and level 5 being the worst.

[0059] Table 1 Raw material ratios and performance test results of examples and comparative examples

[0060]

[0061]

[0062] The notched impact strength of the polypropylene materials prepared in Examples 1-10 of the present invention can reach 10-32 kJ / m 2 , and at the same time, the surface gloss after electroplating is 1-2 levels, and the peeling strength of the electroplated layer is 0-1 level, which has an obvious effect on improving the bonding force between the substrate and the coating after electroplating.

Claims

1. A polypropylene material, characterized in that: By mass parts, it includes the following components: Polypropylene resin: 50 - 75 parts; Inorganic microporous filler: 20 - 40 parts; Compatibilizer: 5 - 15 parts; Among them, the compatibilizer is trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer; the preparation method of the trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer includes the following steps: Mix polyolefin thermoplastic elastomer with trimethylolpropane triacrylate TMPTA, St, and DCP in a container according to the mass ratio of (2000 - 2500) : (60 - 80) : (60 - 80) : (10 - 20), then add it to a twin-screw extruder for melt grafting reaction. The extruded spline is granulated after air cooling to obtain trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer; The polyolefin thermoplastic elastomer is at least one of ethylene-octene copolymer and ethylene-butene copolymer; The inorganic microporous filler is calcium silicate filler.

2. The polypropylene material according to claim 1, characterized in that: The polypropylene resin is at least one of homopolypropylene and copolymer polypropylene.

3. The polypropylene material according to claim 1, characterized in that: The average particle size of the inorganic microporous filler is 0.05 - 3μm.

4. The polypropylene material according to claim 1, wherein: By weight parts, it includes the following components: Polypropylene resin: 50 - 65 parts; Inorganic microporous filler: 30 - 35 parts; Compatibilizer: 6 - 10 parts.

5. A preparation method of the polypropylene material as described in any one of claims 1 - 4, including the following steps: (1) Mix polyolefin thermoplastic elastomer with trimethylolpropane triacrylate TMPTA, St, and DCP in a container according to the mass ratio of (2000 - 2500) : (60 - 80) : (60 - 80) : (10 - 20), then add it to a twin-screw extruder for melt grafting reaction. The extruded spline is granulated after air cooling to obtain trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer; (2) Using trimethylolpropane triacrylate TMPTA grafted polyolefin thermoplastic elastomer as the compatibilizer, add polypropylene resin and inorganic microporous filler in proportion, mix them in a high-speed mixer to obtain a premix; add the premix to the main feeding port of a twin-screw extruder, conduct melt extrusion, granulate and dry to obtain the polypropylene material.

6. An application of the polypropylene material as described in any one of claims 1 - 4 in electroplating-grade modified materials.

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