A foamed polypropylene composite material with good appearance, its preparation method and application

Abstract

The present invention discloses a foamed polypropylene composite material with good appearance, its preparation method and application, belonging to the technical field of polymer engineering plastics; the foamed polypropylene composite material with good appearance provided by the present invention comprises the following components in parts by mass: 53 - 80 parts of PP resin, 8 - 22 parts of polyolefin elastomer, 8 - 22 parts of talcum powder, 0.4 - 2.6 parts of nano filler, and 0.2 - 0.8 parts of foaming agent. The foamed polypropylene composite material with good appearance provided by the present invention has excellent appearance, relatively high flexural modulus and good foaming performance. Moreover, the preparation method provided by the present invention is simple and easy to implement, has cost advantages, has a high degree of design freedom, and is suitable for actual production applications.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer engineering plastics, and particularly relates to a good-appearance foamed polypropylene composite material, a preparation method thereof, and an application thereof. Background Art

[0002] As a general-purpose plastic with high cost performance, polypropylene has excellent mechanical properties such as high strength and high toughness, as well as characteristics such as chemical resistance and high heat resistance after modification, and is widely used in household appliances and automotive products. With the increasingly strong global call for environmental protection, energy conservation and consumption reduction, automotive lightweighting has become a major trend in the automotive industry. By combining polypropylene with micro-foaming technology, the obtained micro-foamed polypropylene material has advantages such as low density, good thermal stability, and chemical corrosion resistance, and is widely used in automotive parts materials such as automotive door panels and instrument panels, and has become one of the lightweight materials favored by vehicle lightweighting and new energy.

[0003] However, when applying the injection molding technology of secondary mold opening and the chemical foaming technology to polypropylene materials, the formed foamed parts are prone to appearance quality problems. The appearance problems are mainly manifested as the easy generation of surface pit defects. The pit defects are manifested as relatively dense circular holes with a size exceeding 1 mm on the surface of the sample, thus affecting the application prospect of the foamed polypropylene parts as appearance parts. At the same time, due to the mechanical properties of the material after foaming, especially the bending modulus has a nearly 40% attenuation, and for automotive interior parts, there are high requirements for the modulus of the material. Therefore, high-modulus foamed polypropylene materials are also the focus of current material development.

[0004] Therefore, there is still a need in the art to develop a polypropylene composite material with good appearance, high modulus, and excellent foaming properties at the same time. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide a good-appearance foamed polypropylene composite material with excellent appearance, relatively high modulus, and excellent foaming properties, a preparation method thereof, and an application thereof.

[0006] To achieve the above purpose, in the first aspect of the present invention, the present invention provides a good-appearance foamed polypropylene composite material, and the good-appearance foamed polypropylene composite material comprises the following components in parts by mass: 53-80 parts of PP resin, 8-22 parts of polyolefin elastomer, 8-22 parts of talcum powder, 0.4-2.6 parts of nano filler, and 0.2-0.8 parts of foaming agent;

[0007] In the PP resin, the mass content of ethylene-propylene rubber is <12%;

[0008] The polyolefin elastomer is ethylene and αA copolymer of olefins, the polyolefin elastomer having a melt mass flow rate of 12 - 32 g / 10 min at 190 °C and 2.16 Kg;

[0009] The D50 particle size of the talc powder is ≤ 5 μm;

[0010] The nano - filler has a dimension with a size ≤ 50 nm;

[0011] The foaming agent is sodium bicarbonate.

[0012] A good - appearance foamed polypropylene composite material provided by the present invention, by selecting appropriate parts by mass and optimized components, has achieved good mutual cooperation among the components, so that the prepared good - appearance foamed polypropylene composite material has excellent appearance, a relatively high flexural modulus and good foaming properties. Specifically, the addition of talc powder within a suitable D50 particle size range can improve the modulus of the material, can improve the dispersibility of the nano - filler, and can also act as a nucleating agent for bubbles together with the nano - filler to improve the foamability of the material; in addition, the present invention selects sodium bicarbonate as the foaming agent, and the addition of sodium bicarbonate and the polyolefin elastomer with a suitable melt mass flow rate can also synergistically improve the appearance defects of the product; it can avoid the melt instability phenomenon during the high - speed forming process of foaming caused by the addition of talc powder or improper selection of the foaming agent, thus generating obvious appearance pit defects; at the same time, the inventors have found that when the mass content of ethylene - propylene rubber in the PP resin is within the scope of the present invention, good modulus and appearance can be obtained simultaneously.

[0013] The PP resin is at least one of homopolypropylene and copolymerized polypropylene. When the selected one is copolymerized polypropylene, the mass content of ethylene - propylene rubber contained therein is < 12%.

[0014] When the components of the good - appearance foamed polypropylene composite material are within the scope of the present invention, excellent comprehensive effects can be obtained. For example, the good - appearance foamed polypropylene composite material may include the following components in parts by mass: 55 - 77 parts of PP resin, 10 - 20 parts of polyolefin elastomer, 10 - 20 parts of talc powder, 0.5 - 2.5 parts of nano - filler, and 0.25 - 0.48 parts of foaming agent.

[0015] In the PP resin, the test method for the mass content of ethylene - propylene rubber is: referring to ASTM D6474 - 99, pre - treating the sample, and separating and quantitatively testing the sample by high - temperature GPC.

[0016] The test method for the melt mass flow rate of the polyolefin elastomer at 190 °C and 2.16 Kg is carried out with reference to ASTM D - 1238 - 2004.

[0017] The test method for the D50 particle size of talcum powder is as follows: Test by a laser particle size analyzer with reference to ISO 13320-1-1999.

[0018] The test method for the dimensional size of nano-fillers is as follows: Measure by a scanning electron microscope.

[0019] The mass percentage of the PP resin in the good-appearance foamed polypropylene composite material is not less than 60%.

[0020] Exemplarily, in the PP resin, the mass content of ethylene-propylene rubber can be any value less than 12%, such as 0-10%, 0-8.7%, 8.7-10%, etc., or can be any point value less than 12% and the range value composed of any two points, such as 11.8%, 11.7%, 11.2%, 11.0%, 10.8%, 10.5%, 10.2%, 10.0%, 9.8%, 9.5%, 9.2%, 9.0%, 8.8%, 8.5%, 8.2%, 8.0%, 7.8%, 7.5%, 7.2%, 7.0%, 6.5%, 6.0%, 5.5%, 5.0%, 4.5%, 4.0%, 3.5%, 3.0%, 2.5%, 2.0%, 1.5%, 1.0%, 0.5%, 0%, etc. Limited by space, they are not listed one by one here. Excellent comprehensive effects can be achieved within the range of the ethylene-propylene rubber content less than 12% given in the present invention.

[0021] Exemplarily, the D50 particle size of the talcum powder can be any value less than or equal to 5μm, such as 0.65-5μm, etc., or can be any point value less than or equal to 5μm or the range value composed of any two points, such as 5μm, 4.8μm, 4.5μm, 4.0μm, 3.5μm, 3.0μm, 2.5μm, 2.0μm, 1.5μm, 1.0μm, 0.5μm, 0.4μm, 0.3μm, 0.2μm, 0.1μm, 0.08μm, 0.05μm, 0.01μm, etc.

[0022] Exemplarily, the size of one dimension of the nano-fillers can be any value less than or equal to 50nm, such as 30-50nm, or can be any point value less than or equal to 50nm or the range value composed of any two points, such as 50nm, 48nm, 45nm, 40nm, 35nm, 30nm, 25nm, 20nm, 15nm, 10nm, 5nm, 4nm, 3nm, 2nm, 1nm, 0.8nm, 0.5nm, 0.1nm, etc. Limited by space, they are not listed one by one here; excellent effects can be achieved within the range of less than or equal to 50nm given in the present invention.

[0023] As a preferred embodiment of the excellent appearance foamed polypropylene composite material of the present invention, the melt mass flow rate of the PP resin at 230 °C and 2.16 Kg is 28-105 g / 10 min;

[0024] And / or, the melt mass flow rate of the polyolefin elastomer at 190 °C and 2.16 Kg is 15-18 g / 10 min.

[0025] The test method for the melt mass flow rate of the PP resin at 230 °C and 2.16 Kg is carried out with reference to ISO1133-2005.

[0026] Exemplarily, the melt mass flow rate of the PP resin at 230 °C and 2.16 Kg can be any value between 28-105 g / 10 min, such as 30-100 g / 10 min, or can be any point value or range value composed of any two points between 28-105 g / 10 min, such as 28 g / 10 min, 30 g / 10 min, 35 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, 55 g / 10 min, 60 g / 10 min, 65 g / 10 min, 70 g / 10 min, 75 g / 10 min, 80 g / 10 min, 85 g / 10 min, 90 g / 10 min, 95 g / 10 min, 100 g / 10 min, 105 g / 10 min, etc. Limited by space, they are not listed one by one here.

[0027] The inventors' research found that when the melt mass flow rate of the polyolefin elastomer at 190 °C and 2.16 Kg is further selected to be 15-18 g / 10 min, the comprehensive effect of the obtained product is better.

[0028] Exemplarily, the melt mass flow rate of the polyolefin elastomer at 190 °C and 2.16 Kg can be any value or range value composed of any two points between 15-18 g / 10 min, such as 15 g / 10 min, 15.2 g / 10 min, 15.5 g / 10 min, 15.8 g / 10 min, 16 g / 10 min, 16.2 g / 10 min, 16.5 g / 10 min, 16.8 g / 10 min, 17 g / 10 min, 17.2 g / 10 min, 17.5 g / 10 min, 17.8 g / 10 min, 18 g / 10 min, etc. Limited by space, they are not listed one by one here. Excellent comprehensive effects can be achieved within the range of 15-18 g / 10 min given in the present invention.

[0029] As a preferred embodiment of the good-looking foamed polypropylene composite material of the present invention, the polyolefin elastomer includes at least one of ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-octene copolymer.

[0030] As a preferred embodiment of the good-looking foamed polypropylene composite material of the present invention, the foaming agent is added in the form of a foaming agent masterbatch, the carrier resin of the foaming agent masterbatch is linear low density polyethylene resin, and based on the foaming agent masterbatch, the mass percentage of the foaming agent is 15-30%.

[0031] Exemplarily, based on the foaming agent masterbatch, the mass percentage of sodium bicarbonate can be any value between 15-30% or the range value composed of any two points. For example, the mass percentage of sodium bicarbonate can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc.; limited by space, they are not listed one by one here. Excellent comprehensive effects can be achieved within the range of 15-30% given in the present invention.

[0032] Preferably, the preparation method of the foaming agent masterbatch is: mixing sodium bicarbonate and linear low density polyethylene resin and extruding to obtain the foaming agent masterbatch.

[0033] Preferably, the melt index of the linear low density polyethylene resin is 15-25 g / 10 min; the melt index of the linear low density polyethylene resin is tested with reference to ASTM D-1238-2004.

[0034] The melt index of the linear low density polyethylene resin can be any point value or the value between any two points between 15-25 g / 10 min. Exemplarily, the melt index of the linear low density polyethylene resin can be 15 g / 10 min, 16 g / 10 min, 17 g / 10 min, 18 g / 10 min, 19 g / 10 min, 20 g / 10 min, 21 g / 10 min, 22 g / 10 min, 23 g / 10 min, 24 g / 10 min, 25 g / 10 min, etc. The effects of the present invention can be achieved within the range of the melt index of the linear low density polyethylene resin given in the present invention.

[0035] As a preferred embodiment of the good-looking foamed polypropylene composite material of the present invention, the decomposition peak temperature of the foaming agent masterbatch < 175 °C and the decomposition enthalpy value < 150 J / g.

[0036] The decomposition peak temperature and decomposition enthalpy value of the foaming agent are tested by the DSC test method, and the DSC test conditions are: 30-200 °C, 10 °C / min, nitrogen atmosphere.

[0037] The inventors' research found that when the decomposition peak temperature of the blowing agent masterbatch is further limited to <175 °C and the decomposition heat enthalpy value is <150 J / g, the comprehensive effect of the obtained product is more excellent.

[0038] Exemplarily, the decomposition peak temperature of the blowing agent masterbatch can be <175 °C, and the decomposition heat enthalpy value can be any value <150 J / g. For example, the decomposition peak temperature of the blowing agent masterbatch can be 169 - 170.9 °C and the decomposition heat enthalpy value can be 114 - 118.9 J / g; such as the decomposition peak temperature is 174 °C, the decomposition heat enthalpy value is 145 J / g, the decomposition peak temperature is 170 °C, the decomposition heat enthalpy value is 140 J / g, the decomposition peak temperature is 165 °C, the decomposition heat enthalpy value is 135 J / g, the decomposition peak temperature is 160 °C, the decomposition heat enthalpy value is 130 J / g, the decomposition peak temperature is 155 °C, the decomposition heat enthalpy value is 125 J / g, the decomposition peak temperature is 150 °C, the decomposition heat enthalpy value is 120 J / g, the decomposition peak temperature is 145 °C, the decomposition heat enthalpy value is 115 J / g, the decomposition peak temperature is 140 °C, the decomposition heat enthalpy value is 110 J / g, the decomposition peak temperature is 135 °C, the decomposition heat enthalpy value is 105 J / g, etc. Due to space limitations, they are not listed one by one here; within the range where the decomposition peak temperature given in the present invention can be <175 °C and the decomposition heat enthalpy value can be <150 J / g, excellent effects can be achieved.

[0039] As a preferred embodiment of the good - appearance foamed polypropylene composite material of the present invention, the nano - filler is selected from at least one of nano - titanium dioxide, nano - organic clay, and nano - silicon dioxide.

[0040] As a preferred embodiment of the good - appearance foamed polypropylene of the present invention, the foamed polypropylene composite material further comprises 0 - 1 part of an additive.

[0041] As a preferred embodiment of the good - appearance foamed polypropylene composite material of the present invention, the additive is selected from at least one of an antioxidant and a light stabilizer.

[0042] Exemplarily, the antioxidant can be at least one of hindered phenol antioxidants or phosphate antioxidants, and the light stabilizer can be a hindered amine light stabilizer.

[0043] In the second aspect of the present invention, the present invention provides a preparation method of a good - appearance foamed polypropylene composite material. The preparation method comprises the following steps: weighing and mixing the dried raw materials except the blowing agent, then melting and kneading, followed by extrusion and pelletizing, and then adding the blowing agent for injection molding to obtain the good - appearance foamed polypropylene composite material.

[0044] As a preferred embodiment of the preparation method of the present invention, the temperature of the melting and kneading is 200 - 210 °C, and the screw speed is 350 - 450 r / min.

[0045] As a preferred embodiment of the preparation method of the present invention, the injection molding temperature is 195 - 205 °C.

[0046] In the third aspect of the present invention, the present invention provides the application of the good - appearance foamed polypropylene composite material in the field of automobiles.

[0047] Exemplarily, the good - appearance foamed polypropylene composite material can be used for preparing automobile interiors.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] A good - appearance foamed polypropylene composite material provided by the present invention, through selecting appropriate mass parts and optimized components, achieves good mutual cooperation among the components, so that the prepared good - appearance foamed polypropylene composite material has excellent appearance, relatively high flexural modulus and good foaming performance. Moreover, the preparation method provided by the present invention is simple and easy to implement, has cost advantages, high design freedom, and is suitable for actual production applications. Detailed Embodiments

[0050] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0051] The reagents, methods and equipment used in the present invention, unless otherwise specified, are all conventional reagents, methods and equipment in the art.

[0052] PP - 1: BX3920, melt index 100 g / 10 min, ethylene - propylene rubber content 8.7%, SK from South Korea;

[0053] PP - 2: BX3800, melt index 30 g / 10 min, ethylene - propylene rubber content 10%, SK from South Korea;

[0054] PP - 3: H9018, melt index 54 g / 10 min, ethylene - propylene rubber content 0%, Lanzhou Petrochemical;

[0055] PP - 4: K7100, melt index 100 g / 10 min, ethylene - propylene rubber content 17.8%, Yanshan Petrochemical;

[0056] Polyolefin elastomer - 1: INFUSE 9807, melt index 15 g / 10 min, Dow Chemical;

[0057] Polyolefin elastomer - 2: DF8200, melt index 18 g / 10 min, Mitsui Chemicals;

[0058] Polyolefin elastomer - 3: ENGAGE 8137, melt index 13 g / 10 min, Dow Chemical;

[0059] Polyolefin elastomer - 4: ENGAGE 8407, melt index 30 g / 10 min, Dow Chemical

[0060] Polyolefin elastomer - 5: ENGAGE 7447, melt index 4 g / 10 min, Dow Chemical;

[0061] Polyolefin elastomer - 6: DF7350, melt index 36 g / 10 min, Mitsui Chemicals;

[0062] Ethylene acrylic elastomer: Lucofin 1400PN, melt index 15 g / 10 min, LUCOBIT Company Talc 1: HTPUTRAL5L, D50 is 0.65 μm, Liaoning Aihai Yimi Mining Co., Ltd.;

[0063] Talc 2: AH - 3000N9, D50 is 5.0 μm, Liaoning Aihai Yimi Mining Co., Ltd.;

[0064] Talc 3: AH - 1250N6, D50 is 8 μm, Liaoning Aihai Yimi Mining Co., Ltd.;

[0065] Calcium carbonate: D50 is 1.55 μm, Dongguan Meilitai Chemical Co., Ltd.;

[0066] Nanofiller 1: Nano - titanium dioxide, TTO - 55D, spherical particles, D50 particle size is 30 nm, Ishihara Corporation, Japan;

[0067] Nanofiller 2: Nano - silica, HN - SP50, spherical particles, D50 particle size is 50 nm, Hengna New Materials Co., Ltd.;

[0068] Nanofiller 3: Nano - organic clay, I.44P, sheet structure, interlayer spacing is 3.5 nm, Nanocor Company;

[0069] Nanofiller 4: Nano - titanium dioxide, CR - 340, spherical particles, D50 particle size is 190 nm, Pangang Vanadium and Titanium Company;

[0070] Blowing agent 1: Sodium bicarbonate masterbatch, EE25C, mass percentage of sodium bicarbonate in the masterbatch is 18%, melt index of LLDPE is 20 g / 10 min, decomposition peak temperature of the masterbatch is 169 °C and decomposition heat enthalpy value is 118.9 J / g, Yonghe Fine Chemicals;

[0071] Blowing agent 2: Sodium bicarbonate masterbatch, F-70, the mass percentage of sodium bicarbonate in the masterbatch is 18%, the melt index of LLDPE is 20 g / 10 min, the decomposition peak temperature of the masterbatch is 170.9 °C and the decomposition heat enthalpy value is 114 J / g, Yonghe Fine Chemical Industry;

[0072] Blowing agent 3: Sodium bicarbonate, commercially available;

[0073] Blowing agent 4: Sodium bicarbonate masterbatch, F-88, the mass percentage of sodium bicarbonate in the masterbatch is 36%, the melt index of LLDPE is 20 g / 10 min, the decomposition peak temperature of the masterbatch is 180.4 °C and the decomposition heat enthalpy value is 258.5 J / g, Yonghe Fine Chemical Industry;

[0074] Blowing agent 5: Azodicarbonamide masterbatch, F-54, the mass percentage of azodicarbonamide in the masterbatch is 20%, the melt index of LLDPE is 20 g / 10 min, the decomposition peak temperature of the masterbatch is 192.2 °C and the decomposition heat enthalpy value is 157.3 J / g, Yonghe Fine Chemical Industry;

[0075] Antioxidant: Antioxidant 1010 and antioxidant 168 are mixed in a mass ratio of 1:1, commercially available;

[0076] Light stabilizer: UV-3853, 2,2,6,6-tetramethyl-4-piperidyl stearate, commercially available;

[0077] The antioxidants and light stabilizers used in the parallel experiments of the examples and comparative examples are kept consistent.

[0078] Examples 1-15 and Comparative Examples 1-14

[0079] The component contents (parts by weight) of the examples and comparative examples of the present invention are shown in Table 1-2;

[0080] Table 1

[0081]

[0082]

[0083] Table 2

[0084]

[0085]

[0086]

[0087] The preparation methods of the examples and comparative examples are as follows:

[0088] After weighing and mixing the dried raw materials except the foaming agent, they were melt-kneaded at 200 - 210 °C with a screw speed of 400 rpm, then extruded and pelletized. Subsequently, the foaming agent was added for a secondary injection molding experiment. The foaming process was as follows: 200 °C, injection speed 140 mm / s, delayed mold opening time 0.5 s, secondary mold opening speed 4 mm / s, to obtain the foamed polypropylene composite material.

[0089] Effect Example

[0090] The effect examples of the present invention verified the performance of the products prepared in the examples and comparative examples; the composite materials in the examples and comparative examples were all tested through a sample mold with dimensions of 100 mm * 100 mm * 1.8 mm. The test items included the following aspects:

[0091] 1. Weight loss rate: 100% * (maximum foaming thickness - 1.8) / maximum foaming thickness; Test method: Conduct a foaming experiment using a mold with an initial thickness of 1.8 mm, gradually increase the mold opening distance at intervals of 0.1 mm until the foamed sample shows surface collapse. Then, the foaming thickness of the sample at the previous mold opening distance is the maximum foaming thickness, and the calculation is performed according to the given calculation formula;

[0092] 2. Appearance pit grade (30% weight loss): Test method: Conduct a foaming experiment using a mold with an initial thickness of 1.8 mm, and by controlling the thickness of the sample after foaming to be 2.34 mm (the weight loss before and after foaming is the same, both 30%), and evaluate the proportion of the area with pits in the total area of the sample based on this sample;

[0093] The specific grading is as follows:

[0094] Grade 0: No appearance pit defects,

[0095] Grade 1: The proportion A of the pit defect area greater than 1 mm in appearance is 0 < A ≤ 5%,

[0096] Grade 2: The proportion A of the pit defect area greater than 1 mm in appearance is 5 < A ≤ 10%,

[0097] Grade 3: The proportion A of the pit defect area greater than 1 mm in appearance is A > 10%;

[0098] 3. Flexural modulus (30% weight loss): Refer to ISO 178 - 2010;

[0099] The test results are shown in Table 3;

[0100] Table 3

[0101]

[0102]

[0103] As can be seen from Table 3, when the technical solution of the present invention is adopted, the obtained product has excellent foaming properties, good appearance and relatively high flexural modulus. Specifically, the maximum weight loss rate of the obtained product is above 45.3%, the pit grade is 0-1, and the flexural modulus is above 1126 MPa;

[0104] As can be seen from Example 1 and Comparative Examples 1-3, when reducing the polyolefin elastomer, talcum powder or nano-filler in the components, the comprehensive effect of the obtained product decreases significantly; when the polyolefin elastomer is missing in Comparative Example 1, the appearance of the obtained product deteriorates significantly, changing from Grade 0 to Grade 3, that is, the area of pit defects with a size greater than 1 mm on the appearance exceeds 10%; when talcum powder is not added in Comparative Example 2, even if the dosage of nano-filler is increased, the foamability of the obtained product deteriorates significantly, and the flexural modulus also decreases significantly. Compared with Example 1, the maximum weight loss rate of Comparative Example 2 decreases by 41.57%, and the flexural modulus decreases by 51.01%; when nano-filler is not added in Comparative Example 3, even if the dosage of talcum powder is increased, the foamability of the obtained product decreases significantly. Compared with Example 1, the maximum weight loss rate decreases by 32.18%;

[0105] As can be seen from Examples 1-3 and Comparative Examples 4-6, the mass parts of the components also affect the performance of the product. When the mass parts of the components in Comparative Examples 4-6 are not within the range given in the present invention, the comprehensive performance of the obtained product decreases significantly;

[0106] As can be seen from Example 1, Examples 5-6 and Comparative Example 7, the content of ethylene-propylene rubber in the PP resin has an obvious effect on the appearance and flexural modulus. When the content of ethylene-propylene rubber in the resin used in Comparative Example 7 is not within the range given in the present invention, not only the appearance grade is reduced to Grade 2, that is, the area of pit defects with a size greater than 1 mm on the appearance is between 5-10%, but also the flexural modulus decreases by 29.57% compared with Example 1;

[0107] It can be seen from Example 1, Examples 7 - 9 and Comparative Examples 8 - 9 that the melt index of the polyolefin elastomer will affect the comprehensive properties of the product. When the melt index of the polyolefin elastomer is further preferably 15 - 18 g / 10 min, the comprehensive properties of the obtained product are more excellent. Specifically, the maximum weight loss rate of the obtained product is above 51.2%, the pit grade is 0, and the flexural modulus is above 1366 MPa; when the melt index of the POE resin in Comparative Examples 8 - 9 is not within the range given in the present invention, compared with Example 1, the obtained appearance grade is reduced to 2, and the expandability and flexural modulus of the material also decrease significantly; it can be seen from Example 1 and Comparative Example 10 that when other elastomers are used to replace the polyolefin elastomer in the present invention, the appearance pit grade of the obtained product is 2, and at the same time, the maximum foaming thickness decreases.

[0108] It can be seen from Example 1, Example 10 and Comparative Example 11 that the selection of the particle size of talcum powder will affect the properties of the product. When the particle size of talcum powder is not within the range of the present invention, the expandability of the obtained product decreases significantly, and the flexural modulus also shows a certain downward trend. Compared with Example 1, the maximum weight loss rate decreases by 37.93%, and the flexural modulus decreases by 30.50%; it can be seen from Example 1 and Comparative Example 12 that when calcium carbonate used in Comparative Example 12 is used to replace talcum powder, the effects of the present invention cannot be achieved.

[0109] It can be seen from Example 1, Examples 11 - 12 and Comparative Example 13 that the size of the nano - filler will also affect the comprehensive properties of the product. When the size of the nano - filler is not within the range of the present invention, the expandability of the obtained product decreases significantly. Compared with Example 1, the maximum weight loss rate decreases by 26.82%.

[0110] It can be seen from Example 1, Examples 13 - 15 and Comparative Example 14 that the selection of the blowing agent will also affect the properties of the product. It can be seen from Example 1 and Example 14 that when the blowing agent and LLDPE are pre - prepared into the form of masterbatch and added in the form of masterbatch, the comprehensive effect of the obtained product is more excellent. If the decomposition peak temperature and decomposition heat enthalpy value of the blowing agent masterbatch are further selected within the range given in the present invention, the comprehensive effect of the obtained product is more excellent. Specifically, the maximum weight loss rate of the obtained product is above 51.7%, the pit grade is 0, and the flexural modulus is above 1378 MPa; if the blowing agent used in Comparative Example 14 is not sodium bicarbonate, the blowing agent selected in the present invention, but other commonly used blowing agent types, the appearance of the obtained product becomes significantly worse, and the grade is 3, that is, the pit defect area with a size greater than 1 mm on the appearance exceeds 10%, and the expandability also shows an obvious downward trend.

[0111] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A good-looking foamed polypropylene composite material, Characterized in that, The good-looking foamed polypropylene composite material comprises the following components in parts by mass: 55 - 77 parts of PP resin, 8 - 22 parts of polyolefin elastomer, 8 - 22 parts of talcum powder, 0.4 - 2.6 parts of nano filler, 0.2 - 0.8 parts of foaming agent; In the PP resin, the mass content of ethylene-propylene rubber < 12%; The polyolefin elastomer is a copolymer of ethylene and α olefin, and the melt mass flow rate of the polyolefin elastomer at 190 °C and 2.16 Kg is 12-32 g / 10 min; The D50 particle size of the talcum powder is ≤ 5μm; The nano filler has a dimension size ≤ 50nm; The foaming agent is sodium bicarbonate.

2. The good-looking foamed polypropylene composite material according to claim 1, Characterized in that, The melt mass flow rate of the PP resin at 230°C and 2.16 Kg is 28 - 105 g / 10 min; And / or, the melt mass flow rate of the polyolefin elastomer at 190°C and 2.16 Kg is 15 - 18 g / 10 min.

3. The good-looking foamed polypropylene composite material according to claim 1, Characterized in that, The polyolefin elastomer includes at least one of ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-octene copolymer.

4. The good-looking foamed polypropylene composite material according to claim 1, Characterized in that, The foaming agent is added in the form of a foaming agent masterbatch, the carrier resin of the foaming agent masterbatch is linear low density polyethylene resin, and calculated by the foaming agent masterbatch, the mass percentage of the foaming agent is 15 - 30%.

5. The good-looking foamed polypropylene composite material according to claim 4, Characterized in that, The decomposition peak temperature of the foaming agent masterbatch < 175°C, and the decomposition enthalpy value < 150 J / g.

6. The good-looking foamed polypropylene composite material according to claim 1, Characterized in that, The nano filler is selected from at least one of nano titanium dioxide, nano organic clay, and nano silicon dioxide.

7. The good-looking foamed polypropylene composite material according to claim 1, Characterized in that, The foamed polypropylene composite material further comprises 0 - 1 part of an auxiliary agent.

8. The good-looking foamed polypropylene composite material according to claim 7, Characterized in that, The auxiliary agent is selected from at least one of antioxidant and light stabilizer.

9. The preparation method of the good-looking foamed polypropylene composite material according to any one of claims 1 - 8, Characterized in that, The preparation method comprises the following steps: weighing and mixing the dried raw materials except the foaming agent, then melt-kneading, followed by extrusion and pelletizing, and then adding the foaming agent for injection molding to obtain the good-looking foamed polypropylene composite material.

10. The application of the good-looking foamed polypropylene composite material according to any one of claims 1 - 8 in the automotive field.

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