Expanded polypropylene composite material, and preparation method and use therefor

Abstract

The application discloses an expanded polypropylene composite material, and a preparation method and use therefor. The expanded polypropylene composite material is prepared from the following raw materials 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 a nano filler and 0.2-0.8 part of a foaming agent. The expanded polypropylene composite material has excellent appearance, high bending modulus and good foaming performance. Moreover, the preparation method is simple and convenient to implement, has a cost advantage, is high in design freedom, and is suitable for actual production and application.

Description

A foamed polypropylene composite material and its preparation method and application Technical Field

[0001] The present application belongs to the technical field of polymer engineering plastics, and in particular relates to a foamed polypropylene composite material and a preparation method and application thereof. Background Art

[0002] Polypropylene (PP), a cost-effective general-purpose plastic, possesses excellent mechanical properties such as high strength and toughness, as well as chemical and heat resistance after modification. It is widely used in home appliances and automotive products. With the growing global demand for environmental protection and energy conservation and consumption reduction, lightweighting vehicles has become a major trend in the automotive industry. Combining PP with micro-foaming technology yields micro-foamed PP with advantages such as low density, excellent thermal stability, and chemical resistance. It is widely used in automotive components such as door panels and instrument panels, and has become a popular lightweight material for vehicle lightweighting and new energy vehicles.

[0003] However, when polypropylene is applied to secondary mold injection molding and chemical foaming, the resulting foamed parts are prone to appearance quality issues. These issues primarily manifest as surface pitting defects, which appear as dense, circular holes larger than 1 mm on the surface of the sample, thus limiting the application prospects of foamed polypropylene parts as exterior components. Furthermore, due to the nearly 40% reduction in the mechanical properties of the foamed material, especially its flexural modulus, automotive interior components require a high modulus. Therefore, high-modulus foamed polypropylene is currently a key focus of material development.

[0004] Therefore, there is a need in the art to develop a polypropylene composite material having good appearance, high modulus and excellent foaming performance. Summary of the Invention

[0005] The present application provides a foamed polypropylene composite material with excellent appearance, high modulus and excellent foaming performance, as well as a preparation method and application thereof.

[0006] The present application provides a foamed polypropylene composite material, the raw materials for preparing the composite material include the following components in parts by weight:

[0007] PP resin 53-80 parts, polyolefin elastomer 8-22 parts, talc 8-22 parts, nano filler 0.4-2.6 parts, foaming agent 0.2-0.8 parts;

[0008] In the PP resin, the mass content of ethylene propylene rubber in the PP resin is 12%;

[0009] 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;

[0010] The D50 particle size of the talc is ≤5 μm;

[0011] The nanofiller has at least one dimension with a size of ≤50 nm;

[0012] The foaming agent is sodium bicarbonate.

[0013] In some embodiments, the PP resin has a melt mass flow rate of 28-105 g / 10 min at 230° C. and 2.16 kg;

[0014] And / or, the polyolefin elastomer has a melt mass flow rate of 15-18 g / 10 min at 190° C. and 2.16 kg.

[0015] In some embodiments, the polyolefin elastomer includes at least one of ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-octene copolymer.

[0016] In some embodiments, the foaming agent is added in the form of foaming agent masterbatch, the carrier resin of the foaming agent masterbatch is linear low-density polyethylene resin, and the mass percentage of the foaming agent is 15-30% based on the foaming agent masterbatch.

[0017] In some embodiments, the decomposition peak temperature of the foaming agent masterbatch is less than 175° C., and the decomposition enthalpy is less than 150 J / g.

[0018] In some embodiments, the nanofiller is selected from at least one of nano-titanium dioxide, nano-organic clay, and nano-silicon dioxide.

[0019] In some embodiments, the raw materials for preparing the foamed polypropylene composite material further include the following components in parts by weight: 0-1 part of an auxiliary agent.

[0020] In some embodiments, the auxiliary agent is selected from at least one of an antioxidant and a light stabilizer.

[0021] The present application also provides a method for preparing the foamed polypropylene composite material, comprising the following steps: weighing the dried raw materials except the foaming agent, mixing them, and then melt-kneading them, followed by extrusion and granulation, and then adding the foaming agent for injection molding to obtain the foamed polypropylene composite material.

[0022] The present application also provides application of the foamed polypropylene composite material in the automotive field.

[0023] In some embodiments, the foamed polypropylene composite material is a good appearance foamed polypropylene composite material.

[0024] Compared with the prior art, the present invention has the following advantages:

[0025] The foamed polypropylene composite material provided herein is achieved by selecting and optimizing components in appropriate weight proportions, thereby achieving a good interaction between the components. This results in the foamed polypropylene composite material having an excellent appearance, a high flexural modulus, and good foaming properties. Furthermore, the preparation method provided herein is simple and easy to implement, offers cost advantages, and provides a high degree of design freedom, making it suitable for practical production applications. DETAILED DESCRIPTION

[0026] The first aspect of the present application provides a foamed polypropylene composite material, wherein the raw materials for preparing the foamed polypropylene composite material include the following components in parts by mass: 53-80 parts of PP resin, 8-22 parts of polyolefin elastomer, 8-22 parts of talc powder, 0.4-2.6 parts of nanofiller, and 0.2-0.8 parts of foaming agent;

[0027] In the PP resin, the mass content of ethylene propylene rubber is less than 12%;

[0028] 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;

[0029] The D50 particle size of the talc is ≤5 μm;

[0030] The nanofiller has one dimension with a size of ≤50 nm;

[0031] The foaming agent is sodium bicarbonate.

[0032] The foamed polypropylene composite material provided by the present application is achieved by selecting appropriate mass parts and after preferred components, and the components achieve good mutual cooperation, so that the prepared foamed polypropylene composite material has excellent appearance, high bending modulus and good foaming performance. Specifically, the addition of talcum powder within the appropriate D50 particle size range can improve the modulus of the material, and can improve the dispersibility of the nanofiller, and can also act together with the nanofiller as a nucleating agent for bubbles to improve the expandability of the material; In addition, the present application selects sodium bicarbonate as a foaming agent, and the addition of sodium bicarbonate and a polyolefin elastomer with a suitable melt mass flow rate can also synergistically improve the appearance defects of the product; avoid the generation of melt instability during the high-speed molding process of foaming caused by the addition of talcum powder or the improper selection of the foaming agent, thereby producing a more obvious appearance pit defect; At the same time, the inventors have found that the mass content of ethylene propylene rubber in PP resin can only achieve good modulus and appearance at the same time when it is within the scope of this application.

[0033] In some embodiments, the PP resin is at least one of homopolypropylene and copolymer polypropylene, wherein when copolymer polypropylene is selected, the mass content of EPDM contained therein is <12%.

[0034] When the components of the foamed polypropylene composite material are within the scope of this application, excellent comprehensive effects can be achieved. In some embodiments, the raw materials for preparing the foamed polypropylene composite material may include the following components by weight: 55-77 parts PP resin, 10-20 parts polyolefin elastomer, 10-20 parts talc, 0.5-2.5 parts nanofiller, and 0.25-0.48 parts foaming agent.

[0035] In some embodiments, the test method for the mass content of EPDM in PP resin is: refer to ASTM D6474-99, perform sample pretreatment, and use high-temperature GPC to separate and quantitatively test the sample.

[0036] In some embodiments, the melt mass flow rate of the polyolefin elastomer at 190° C. and 2.16 kg is tested in accordance with ASTM D-1238-2004.

[0037] In some embodiments, the D50 particle size of talc is measured by a laser particle size analyzer according to ISO 13320-1-1999.

[0038] In some embodiments, the size of the nanofiller is measured by scanning electron microscopy.

[0039] In some embodiments, the mass percentage of the PP resin in the foamed polypropylene composite material is not less than 60%.

[0040] In some embodiments, the mass content of EPDM in the PP resin may be any value less than 12%, such as 0-10%, 0-8.7%, 8.7-10%, etc., or any point value less than 12% and a range value consisting 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., as well as ranges consisting of any two of the above values, are not listed here one by one due to space limitations. Excellent comprehensive effects can be achieved within the range of <12% of the EPDM content given in this application.

[0041] In some embodiments, the D50 particle size of the talc can be any value ≤5 μm, such as 0.65-5 μm, etc., or can be any point value ≤5 μm or a range value consisting of any two points, such as 5 μm, 4.8 μm, 4.5 μm, 4.0 μm, 3.5 μm, 3.0 μm, 2.5 μm, 2.0 μm, 1.5 μm, 1.0 μm, 0.5 μm, 0.4 μm, 0.3 μm, 0.2 μm, 0.1 μm, 0.08 μm, 0.05 μm, 0.01 μm, etc. and a range value consisting of any two points among the above values.

[0042] In some embodiments, the size of one dimension of the nanofiller can be any value ≤50 nm, such as 30-50 nm, or any point value ≤50 nm or a range value consisting of any two points, such as 50 nm, 48 nm, 45 nm, 40 nm, 35 nm, 30 nm, 25 nm, 20 nm, 15 nm, 10 nm, 5 nm, 4 nm, 3 nm, 2 nm, 1 nm, 0.8 nm, 0.5 nm, 0.1 nm, etc., and a range value consisting of any two points in the above values. Due to space limitations, they are not listed here one by one; within the range of ≤50 nm given in this application, excellent effects can be achieved.

[0043] In some embodiments, the PP resin has a melt mass flow rate of 28-105 g / 10 min at 230° C. and 2.16 kg;

[0044] And / or, the polyolefin elastomer has a melt mass flow rate of 15-18 g / 10 min at 190° C. and 2.16 kg.

[0045] In some embodiments, the melt flow rate of the PP resin at 230° C. and 2.16 kg is tested in accordance with ISO 1133-2005.

[0046] In some embodiments, the melt mass flow rate of the PP resin at 230°C and 2.16 kg can be any value between 28 and 105 g / 10 min, such as 30-100 g / 10 min, or can be any point value between 28 and 105 g / 10 min or a range value consisting of any two points, 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., as well as range values ​​consisting of any two points among the above values. Due to space limitations, they are not listed here one by one.

[0047] The inventors have 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 overall effect of the obtained product is better.

[0048] In some embodiments, the melt mass flow rate of the polyolefin elastomer at 190°C and 2.16 kg can be any value between 15 and 18 g / 10 min, or a range value consisting of any two points, 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., and a range value consisting of any two points among the above values. Due to space limitations, they are not listed here one by one. Excellent comprehensive effects can be achieved within the range of 15-18 g / 10 min given in this application.

[0049] In some embodiments, the polyolefin elastomer includes at least one of ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-octene copolymer.

[0050] In some embodiments, the foaming agent is added in the form of foaming agent masterbatch, the carrier resin of the foaming agent masterbatch is linear low-density polyethylene resin, and the mass percentage of the foaming agent is 15-30% based on the foaming agent masterbatch.

[0051] In some embodiments, based on the foaming agent masterbatch, the mass percentage of sodium bicarbonate can be any value between 15-30% or a range value consisting 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., as well as a range value consisting of any two points in the above values; due to space limitations, they are not listed here one by one, and excellent comprehensive effects can be achieved within the range of 15-30% given in this application.

[0052] In some embodiments, the method for preparing the foaming agent masterbatch is: mixing sodium bicarbonate and linear low-density polyethylene resin and extruding them to obtain the foaming agent masterbatch.

[0053] In some embodiments, the melt index of the linear low density polyethylene resin is 15-25 g / 10 min. In some embodiments, the melt index of the linear low density polyethylene resin is tested according to ASTM D-1238-2004.

[0054] In some embodiments, the melt index of the linear low density polyethylene resin may be any point value between 15-25 g / 10 min or a value between any two points. For example, the melt index of the linear low density polyethylene resin may 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., and a range value consisting of any two points among the above values. Within the melt index range of the linear low density polyethylene resin given in this application, the effects of the present application can be achieved.

[0055] In some embodiments, the decomposition peak temperature of the foaming agent masterbatch is less than 175° C., and the decomposition enthalpy is less than 150 J / g.

[0056] In some embodiments, the decomposition peak temperature and decomposition enthalpy of the foaming agent are tested using a DSC test method, and the DSC test conditions are: 30-200° C., 10° C. / min, and a nitrogen atmosphere.

[0057] The inventors have found that when the decomposition peak temperature of the foaming agent masterbatch is further limited to less than 175°C and the decomposition enthalpy value is less than 150J / g, the overall effect of the obtained product is more excellent.

[0058] In some embodiments, the decomposition peak temperature of the foaming agent masterbatch may be <175°C, and the decomposition enthalpy value may be any value <150J / g, such as the decomposition peak temperature of the foaming agent masterbatch may be 169-170.9°C and the decomposition enthalpy value may be 114-118.9J / g; such as the decomposition peak temperature of 174°C, the decomposition enthalpy value is 145J / g, the decomposition peak temperature of 170°C, the decomposition enthalpy value is 140J / g, the decomposition peak temperature of 165°C, the decomposition enthalpy value is 135J / g, the decomposition peak temperature of 160°C, the decomposition enthalpy value is 130 ... The temperature is 155°C, the decomposition enthalpy value is 125J / g, the decomposition peak temperature is 150°C, the decomposition enthalpy value is 120J / g, the decomposition peak temperature is 145°C, the decomposition enthalpy value is 115J / g, the decomposition peak temperature is 140°C, the decomposition enthalpy value is 110J / g, the decomposition peak temperature is 135°C, the decomposition enthalpy value is 105J / g, etc., as well as the range values ​​composed of any two points in the above values. Due to space limitations, they are not listed here one by one; within the range of the decomposition peak temperature given in this application, which can be <175°C and the decomposition enthalpy value can be <150J / g, excellent results can be achieved.

[0059] In some embodiments, the nanofiller is selected from at least one of nano-titanium dioxide, nano-organic clay, and nano-silicon dioxide.

[0060] In some embodiments, the raw materials for preparing the foamed polypropylene composite material further include 0-1 part of an auxiliary agent.

[0061] In some embodiments, the auxiliary agent is selected from at least one of an antioxidant and a light stabilizer.

[0062] In some embodiments, the antioxidant may be at least one of a hindered phenol antioxidant or a phosphate antioxidant, and the light stabilizer may be a hindered amine light stabilizer.

[0063] The second aspect of the present application provides a method for preparing the foamed polypropylene composite material, which comprises the following steps: weighing the dried raw materials except the foaming agent, mixing them, and then melt-kneading them, followed by extrusion and granulation, and then adding the foaming agent for injection molding to obtain the foamed polypropylene composite material.

[0064] In some embodiments, the melt mixing temperature is 200-210° C., and the screw speed is 350-450 r / min.

[0065] In some embodiments, the injection molding temperature is 195-205°C.

[0066] The third aspect of the present application provides application of the foamed polypropylene composite material in the automotive field.

[0067] In some embodiments, the foamed polypropylene composite material can be used to prepare automotive interiors.

[0068] In some embodiments, the foamed polypropylene composite material is a good appearance foamed polypropylene composite material.

[0069] It is understandable that the present application also discloses a raw material composition for preparing the foamed polypropylene composite material described in any of the above embodiments.

[0070] In order to better illustrate the purpose, technical solutions and advantages of this application, this application will be further described below in conjunction with specific embodiments.

[0071] Unless otherwise specified, the reagents, methods and equipment used in this application are conventional reagents, methods and equipment in the art.

[0072] PP-1: BX3920, melt index (i.e., melt mass flow rate; in this embodiment, the melt index was measured at 230°C, 2.16 kg) 100 g / 10 min, EPDM content 8.7%, South Korea SK;

[0073] PP-2: BX3800, melt index 30g / 10min, EPDM content 10%, South Korea SK;

[0074] PP-3: H9018, melt index 54g / 10min, EPDM content 0%, Lanzhou Petrochemical;

[0075] PP-4: K7100, melt index 100g / 10min, EPDM content 17.8%, Yanshan Petrochemical;

[0076] Polyolefin elastomer-1: INFUSE 9807, melt index (i.e., melt mass flow rate; in this embodiment, the melt index was measured at 190° C. and 2.16 kg) of 15 g / 10 min, Dow Chemical;

[0077] Polyolefin elastomer-2: DF8200, melt index 18g / 10min, Mitsui Chemicals;

[0078] Polyolefin elastomer-3: ENGAGE 8137, melt index 13 g / 10 min, Dow Chemical;

[0079] Polyolefin elastomer-4: ENGAGE 8407, melt index 30g / 10min, Dow Chemical

[0080] Polyolefin elastomer-5: ENGAGE 7447, melt index 4 g / 10 min, Dow Chemical;

[0081] Polyolefin elastomer-6: DF7350, melt index 36g / 10min, Mitsui Chemicals;

[0082] Ethylene acrylic acid elastomer: Lucofin 1400PN, melt index 15 g / 10 min, LUCOBIT talc 1: HTPUTRAL5L, D50 0.65 μm, Liaoning Aihai Yimi Mining Co., Ltd.

[0083] Talc 2: AH-3000N9, D50 5.0 μm, Liaoning Aihaiyimi Mining Co., Ltd.

[0084] Talc 3: AH-1250N6, D50 8 μm, Liaoning Aihaiyimi Mining Co., Ltd.

[0085] Calcium carbonate: D50 is 1.55 μm, Dongguan Meilitai Chemical Co., Ltd.

[0086] Nanofiller 1: Nano titanium dioxide, TTO-55D, spherical particles, D50 particle size 30 nm, Ishihara Co., Ltd., Japan;

[0087] Nanofiller 2: Nanosilica, HN-SP50, spherical particles, D50 particle size 50 nm, Hengna New Materials Co., Ltd.

[0088] Nanofiller 3: Nanoorganic clay, I.44P, lamellar structure, interlamellar spacing of 3.5 nm, Nanocor;

[0089] Nanofiller 4: Nano titanium dioxide, CR-340, spherical particles, D50 particle size 190 nm, Pangang Vanadium Titanium Company;

[0090] Foaming agent 1: sodium bicarbonate masterbatch, EE25C, with a sodium bicarbonate content of 18% by mass, an LLDPE melt index of 20 g / 10 min, a decomposition peak temperature of 169°C, and a decomposition enthalpy of 118.9 J / g, from Yonghe Fine Chemicals.

[0091] Foaming agent 2: sodium bicarbonate masterbatch, F-70, with a sodium bicarbonate content of 18% by mass, an LLDPE melt index of 20 g / 10 min, a decomposition peak temperature of 170.9°C, and a decomposition enthalpy of 114 J / g, from Yonghe Fine Chemicals.

[0092] Foaming agent 3: sodium bicarbonate, commercially available;

[0093] Foaming agent 4: sodium bicarbonate masterbatch, F-88, the mass percentage of sodium bicarbonate in the masterbatch is 36%, the melt index of LLDPE is 20g / 10min, the decomposition peak temperature of the masterbatch is 180.4℃ and the decomposition enthalpy value is 258.5J / g, Yonghe Fine Chemicals;

[0094] Foaming agent 5: azodicarbonamide masterbatch, F-54, with a mass percentage of azodicarbonamide in the masterbatch of 20%, a melt index of LLDPE of 20 g / 10 min, a decomposition peak temperature of 192.2°C, and a decomposition enthalpy of 157.3 J / g, from Yonghe Fine Chemicals;

[0095] Antioxidant: Antioxidant 1010 and antioxidant 168 were mixed in a mass ratio of 1:1 and were commercially available;

[0096] Light stabilizer: UV-3853, 2,2,6,6-tetramethyl-4-piperidinyl stearate, commercially available;

[0097] The antioxidants and light stabilizers used in the parallel experiments of the examples and comparative examples remained consistent.

[0098] Examples 1-15 and Comparative Examples 1-14

[0099] The component contents (parts by weight) of the examples and comparative examples of the present application are shown in Table 1-2;

[0100] Table 1

[0101] Table 2

[0102] The preparation methods of the embodiments and comparative examples are as follows:

[0103] The dried raw materials except the foaming agent were weighed and mixed, and then melt-kneaded at 200-210°C with a screw speed of 400 rpm. Subsequently, the mixture was extruded and granulated. Then, the foaming agent was added to conduct a secondary mold opening injection molding experiment. The foaming process was as follows: 200°C, injection speed 140 mm / s, delayed mold opening time 0.5 s, and secondary mold opening speed 4 mm / s to obtain a foamed polypropylene composite material.

[0104] Effect Examples

[0105] The present application effect example verifies the performance of the products prepared in the embodiment and the comparative example; the composite materials in the embodiment and the comparative example are tested through a sample mold with a size of 100mm*100mm*1.8mm. The test items include the following aspects:

[0106] 1. Maximum weight loss rate: 100% * (maximum foaming thickness - 1.8) / maximum foaming thickness; Test method: Use a mold with an initial thickness of 1.8mm to conduct a foaming experiment, and gradually increase the mold opening distance in intervals of 0.1mm until the foamed sample produces surface collapse. The foaming thickness of the sample at the previous mold opening distance is the maximum foaming thickness, and it is calculated according to the given calculation formula;

[0107] 2. Appearance Dimpling Grade (30% Weight Loss): Test method: A foaming experiment is conducted using a mold with an initial thickness of 1.8mm. The thickness of the sample after foaming is controlled to 2.34mm (the weight loss before and after foaming remains the same, both at 30%). The proportion of the area of ​​the dents to the total area of ​​the sample is evaluated.

[0108] The specific classifications are:

[0109] Level 0: No external pit defects.

[0110] Level 1: The area of ​​the pit defect larger than 1mm accounts for A0<A≤5%.

[0111] Level 2: The area of ​​the pit defect larger than 1mm accounts for A5<A≤10%;

[0112] Level 3: The area of ​​the pit defect larger than 1 mm accounts for A>10%;

[0113] 3. Flexural modulus (30% weight loss): refer to ISO 178-2010;

[0114] The test results are shown in Table 3;

[0115] Table 3

[0116] As can be seen from Table 3, when the technical solution of the present application is adopted, the obtained product has excellent foaming properties, good appearance and 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.

[0117] It can be seen from Example 1 and Comparative Examples 1-3 that, no matter whether the polyolefin elastomer, talc or nanofiller in the components is reduced, the overall effect of the obtained product is significantly reduced; when the polyolefin elastomer is missing in Comparative Example 1, the appearance of the obtained product is significantly deteriorated, from grade 0 to grade 3, that is, the area of ​​pit defects larger than 1 mm on the appearance exceeds 10%; when talc is not added in Comparative Example 2, even if the amount of nanofiller is increased, the expandability of the obtained product is significantly deteriorated, and the flexural modulus is also significantly reduced. Compared with Example 1, the maximum weight loss rate of Comparative Example 2 is reduced by 41.57%, and the flexural modulus is reduced by 51.01%; when no nanofiller is added in Comparative Example 3, even if the amount of talc is increased, the expandability of the obtained product is significantly reduced. Compared with Example 1, the maximum weight loss rate is reduced by 32.18%.

[0118] It can be seen from Examples 1-3 and Comparative Examples 4-6 that the mass parts of the components will also affect the performance of the product. When the mass parts of the components in Comparative Examples 4-6 are not within the ranges given in this application, the comprehensive performance of the obtained products is significantly reduced.

[0119] It can be seen from Example 1, Examples 5-6, and Comparative Example 7 that the EPDM content in the PP resin has a significant effect on the appearance and flexural modulus. When the EPDM content of the resin used in Comparative Example 7 is not within the range given in this application, not only is the appearance grade reduced to Grade 2, that is, the area of ​​pit defects larger than 1 mm on the appearance is between 5-10%, but the flexural modulus also decreases by 29.57% compared to Example 1.

[0120] 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 performance of the product. When the melt index of the polyolefin elastomer is further preferably 15-18 g / 10 min, the comprehensive performance of the obtained product is better. Specifically, the maximum weight loss rate of the obtained product is above 51.2%, the pit grade is level 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 this application, compared with Example 1, the obtained appearance grade is reduced to level 2, and the expandability and flexural modulus of the material are also significantly reduced. It can be seen from Example 1 and Comparative Example 10 that when other elastomers are used instead of the polyolefin elastomer in this application, the appearance pit grade of the obtained product is level 2, and the maximum foaming thickness is reduced.

[0121] It can be seen from Example 1, Example 10 and Comparative Example 11 that the selection of talc powder particle size will affect the performance of the product. When the particle size of the talc powder is not within the range of this application, 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 the calcium carbonate used in Comparative Example 12 replaces the talc powder, the effect of this application cannot be achieved.

[0122] It can be seen from Example 1, Examples 11-12 and Comparative Example 13 that the size of the nanofiller also affects the overall performance of the product. When the size of the nanofiller is not within the range of this application, the expandability of the obtained product is significantly reduced. Compared with Example 1, the maximum weight loss rate is reduced by 26.82%;

[0123] It can be seen from Example 1, Examples 13-15 and Comparative Example 14 that the selection of foaming agent will also affect the performance of the product. It can be seen from Example 1 and Example 14 that when the foaming 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 enthalpy of the foaming agent masterbatch are further selected within the range given in this application, the comprehensive effect of the obtained product is even better. Specifically, the maximum weight loss rate of the obtained product is above 51.7%, the pit level is level 0, and the bending modulus is above 1378 MPa; if the foaming agent used in Comparative Example 14 is not the foaming agent sodium bicarbonate selected in this application but other commonly used foaming agent types, the appearance of the obtained product is significantly deteriorated, with a level of 3, that is, the area of ​​pit defects larger than 1 mm in appearance exceeds 10%, and the expandability also shows a significant downward trend.

[0124] Finally, it should be noted that the above embodiments are intended to illustrate the technical solutions of the present application rather than to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A foamed polypropylene composite material, characterized in that: The raw materials for preparing the foamed polypropylene composite material include the following components in parts by weight: PP (polypropylene) resin 53-80 parts, polyolefin elastomer 8-22 parts, talc 8-22 parts, nano filler 0.4-2.6 parts, foaming agent 0.2-0.8 parts; In the PP resin, the mass content of ethylene propylene rubber in the PP resin is less than 12%; The polyolefin elastomer is a copolymer of ethylene and alpha 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 talc is ≤5 μm; The nanofiller has at least one dimension with a size of ≤50 nm; The foaming agent is sodium bicarbonate.

2. The 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 polyolefin elastomer has a melt mass flow rate of 15-18 g / 10 min at 190° C. and 2.16 kg.

3. The 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 foamed polypropylene composite material according to claim 1, characterized in that: The foaming agent is added in the form of foaming agent masterbatch, the carrier resin of the foaming agent masterbatch is linear low-density polyethylene resin, and the mass percentage of the foaming agent is 15-30% based on the foaming agent masterbatch.

5. The foamed polypropylene composite material according to claim 4, characterized in that: The decomposition peak temperature of the foaming agent masterbatch is less than 175° C., and the decomposition enthalpy value is less than 150 J / g.

6. The 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 foamed polypropylene composite material according to claim 1, characterized in that: The raw materials for preparing the foamed polypropylene composite material also include the following components in parts by weight: 0-1 part of auxiliary agent.

8. The foamed polypropylene composite material according to claim 7, characterized in that: The auxiliary agent is selected from at least one of an antioxidant and a light stabilizer.

9. The method for preparing the foamed polypropylene composite material according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: weighing and mixing the dried raw materials except the foaming agent, melting and kneading them, then extruding and granulating them, and then adding the foaming agent for injection molding to obtain the foamed polypropylene composite material.

10. Use of the foamed polypropylene composite material according to any one of claims 1 to 8 in the automotive field.

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