Foamed polypropylene composition, preparation method therefor, and use thereof

Abstract

Disclosed in the present application are a foamed polypropylene composition, a preparation method therefor, and a use thereof. The foamed polypropylene composition comprises the following components in parts by mass: 52-98 parts of PP resin, 0.3-3.2 parts of high specific surface area filler, 0.3-2.2 parts of polyhydroxy compound, and 0.3-2.2 parts of melt elasticity regulator. In the foamed polypropylene composition, PP resin with a certain melt flow rate is selected and compounded with the high specific surface area filler, the polyhydroxy compound, and the melt elasticity regulator in order to increase the expandibility of the composition; the cell size of the composition can be reduced and the product also has high fluidity, facilitating the rapid forming of injection moulding foam.

Description

A foamed polypropylene composition 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 composition, a preparation method thereof, and an application thereof. Background Art

[0002] Polypropylene, 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 polypropylene with micro-foaming technology yields micro-foamed polypropylene 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] Polypropylene is a semi-crystalline material with low melt strength, which can easily lead to defects such as combined and interlocking bubbles. Furthermore, for automotive interior door panels, the large size and complex shape of the integrated components, combined with thin-wall technology, require higher fluidity for the polypropylene currently used in door panels. However, the melt strength of polypropylene typically decreases significantly as fluidity increases, resulting in poor foaming performance. Furthermore, because chemical foaming involves mixing a foaming agent into the injection molding process and then melt-mixing and dispersing it with the polypropylene material under the influence of the injection molding machine screw and heating, the decomposition gases tend to accumulate in the polypropylene melt, resulting in coarse bubbles in the final material.

[0004] Therefore, there is a need in the art to develop a polypropylene composition having high fluidity and excellent foaming properties. Summary of the Invention

[0005] The present application provides a foamed polypropylene composition with excellent flowability and foaming properties, as well as a preparation method and application thereof.

[0006] The present application provides a foamed polypropylene composition, wherein the raw materials for preparing the foamed polypropylene composition include the following components in parts by weight: 52-98 parts of polypropylene (PP) resin, 0.3-3.2 parts of a high specific surface area filler, 0.3-2.2 parts of a polyhydroxy compound, and 0.3-2.2 parts of a melt elasticity regulator;

[0007] The average specific surface area of ​​the high specific surface area filler is greater than 40m 2 / g;

[0008] The hydroxyl content of the polyol is greater than 6%.

[0009] The melt elasticity modifier increases the viscoelastic temperature of the PP resin by more than 20°C after being mixed with the PP resin;

[0010] The PP resin has a melt mass flow rate of 55-105 g / 10 min at 230° C. and 2.16 kg.

[0011] In some embodiments, the average specific surface area of ​​the high surface area filler is 46-75 m 2 / g;

[0012] and / or, the polyol has a hydroxyl content of 9.4-11.8%;

[0013] and / or, the melt elasticity modifier increases the viscoelastic temperature of the PP resin by 31-36° C. after being mixed with the PP resin;

[0014] And / or, the PP resin has a melt mass flow rate of 80-90 g / 10 min at 230° C. and 2.16 kg.

[0015] In some embodiments, the melt elasticity modifier is a sorbitol compound;

[0016] And / or, the high specific surface area filler is selected from at least one of titanium dioxide, fumed alumina, porous silica gel, silicon dioxide, and organic clay;

[0017] And / or, the polyhydroxy compound is at least one selected from glyceryl monostearate, sorbitan monostearate, sorbitan monolaurate, oleic acid diethanolamide, and polyethylene glycol.

[0018] In some embodiments, the sorbitol compound is at least one selected from 1,3-2,4-bis(p-methylbenzylidene)sorbitol and 1,3-2,4-bis(3,4-dimethylbenzylidene)sorbitol.

[0019] In some embodiments, the raw materials for preparing the foamed polypropylene composition further include the following components in parts by mass: 0-20 parts of filler, 0-20 parts of toughening agent, and 0-1 part of auxiliary agent.

[0020] In some embodiments, the filler is selected from at least one of talc, calcium carbonate, barium sulfate, and glass fiber;

[0021] And / or, the toughening agent is selected from at least one of POE (polyolefin elastomer), SEBS (styrene-ethylene-butylene-styrene block copolymer), and EPDM (ethylene propylene diene monomer);

[0022] And / or, the auxiliary agent is selected from at least one of an antioxidant and a light stabilizer.

[0023] In some embodiments, the preparation method comprises the following steps: weighing the dried raw materials, mixing them, and then melt-kneading them, followed by extrusion and granulation to obtain a foamed polypropylene composition.

[0024] The present application also provides a foamed article, which is produced by foaming the foamed polypropylene composition.

[0025] The present application also provides application of the foamed polypropylene composition in the automotive field.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] The present application provides a foamed polypropylene composition that improves the expandability of the composition by selecting a PP resin with a certain melt flow rate and compounding it with a high specific surface area filler, a polyol, and a melt elasticity modifier. This allows for a reduction in the cell size of the composition, resulting in high fluidity for the final product and facilitating rapid molding by injection molding. The preparation method provided herein is simple, easy to implement, and beneficial for actual production, offering cost advantages and a high degree of design freedom. The resulting product exhibits high expandability, fine-grained cells, and high fluidity when used for chemical foaming, making it suitable for high-speed molding by injection molding. DETAILED DESCRIPTION

[0028] The first aspect of the present application provides a foamed polypropylene composition, wherein the raw materials for preparing the foamed polypropylene composition include the following components in parts by weight: 52-98 parts of PP resin, 0.3-3.2 parts of high specific surface area filler, 0.3-2.2 parts of polyhydroxy compound, and 0.3-2.2 parts of melt elasticity regulator;

[0029] The average specific surface area of ​​the high specific surface area filler is greater than 40m 2 / g;

[0030] The hydroxyl content of the polyol is greater than 6%.

[0031] The sorbitol compound increases the viscoelastic temperature of the PP resin by more than 20°C after being mixed with the PP resin;

[0032] The PP resin has a melt mass flow rate of 55-105 g / 10 min at 230° C. and 2.16 kg.

[0033] The foamed polypropylene composition provided in this application improves the expandability of the composition by selecting a PP resin with a certain melt mass flow rate, compounding a high specific surface area filler, a polyol, and a melt elasticity modifier. This improves the expandability of the composition while reducing the cell size of the composition, achieving high fluidity of the final product and facilitating rapid molding by injection molding. Specifically, by adding a suitable high specific surface area filler and a melt elasticity modifier as heterogeneous nucleating agents for the bubbles, the expandability and cell size of the material are improved. Furthermore, by using a polyol to improve the dispersion and distribution of the foaming agent in the melt, combined with the melt elasticity modifier's regulation of the material's viscoelasticity, the overall cell structure of the material is improved.

[0034] In some embodiments, the average specific surface area of ​​the high specific surface area filler is determined by a test method based on GB-T19587-2004.

[0035] In some embodiments, the hydroxyl content in the polyhydroxy compound is the mass percentage of hydroxyl groups, which is calculated by chemical formula (calculation formula: hydroxyl content = 17*N / M*100%, where N is the number of hydroxyl groups in the molecular structure and M is the molecular mass).

[0036] In some embodiments, the change in the viscoelastic temperature of the PP resin caused by mixing the melt elasticity modifier with the PP resin is calculated as follows: Viscoelastic temperature change = viscoelastic temperature of the mixture after mixing the PP resin and the melt elasticity modifier - viscoelastic temperature of the PP resin. In some embodiments, the viscoelastic temperature is tested by adding 0.5 wt% of the melt elasticity modifier to PP resin BX3920 (in some embodiments, manufactured by SK, South Korea), extruding the modified plastic particles by screw extrusion. The particles are then hot-pressed at 190°C into 1 mm specimens, and 25 mm discs are cut out for rotational rheology testing. The rotational rheometer test parameters are as follows: 25 mm plate spacing, 1 mm, strain 2%, frequency 1 rad / s, test temperature 200°C-120°C, and cooling rate -5°C / min.

[0037] In some embodiments, the melt mass flow rate of the PP resin at 230° C. and 2.16 kg is tested according to ISO 1133-2005. In some embodiments, the PP resin is at least one of homopolypropylene and copolymer polypropylene.

[0038] In some embodiments, the average specific surface area of ​​the high specific surface area may be >40 m 2 Any value of / g, such as 46-75m 2 / g, 46-85m 2 / g, 75-85m 2 / g, etc., or can be >40m2 / g any point value or range value composed of any two points, such as 41m 2 / g、45m 2 / g、48m 2 / g, 50m 2 / g、52m 2 / g、55m 2 / g、58m 2 / g, 60m 2 / g、62m 2 / g、65m 2 / g、68m 2 / g、70m 2 / g、72m 2 / g、75m 2 / g、78m 2 / g、80m 2 / g、82m 2 / g、85m 2 / g、88m 2 / g、90m 2 / g、92m 2 / g、95m 2 / g、98m 2 / g、100m 2 / g, etc. and the range values ​​composed of any two points in the above values ​​are not listed here due to space limitations. The average specific surface area given in this application can be >40m 2 / g range can achieve excellent comprehensive effects.

[0039] In some embodiments, the high specific surface area has an average specific surface area of ​​46-75 m 2 / g. The inventors found that when the average specific surface area of ​​the high specific surface area is further selected to be 46-75m 2 / g, the comprehensive effect of the obtained product is more excellent.

[0040] In some embodiments, the hydroxyl content of the polyol may be any value greater than 6%, such as 9.4-11.8%, 9.4-12.5%, 11.8-12.5%, etc., or any point value greater than 6% or a range of values ​​consisting of any two points, such as 6.1%, 6.3%, 6.5%, 6.8%, 7.0%, 7.2%, 7.5%, 7.8%, 8.0%, 8.2%, 8.5%, 8.8%, 9.0%, 9. .2%, 9.5%, 9.8%, 10.0%, 10.2%, 10.5%, 10.8%, 11.0%, 11.2%, 11.5%, 11.8%, 12.0%, 12.2%, 12.5%, 12.8%, 13.0%, etc. and ranges consisting of any two of the above values ​​are not listed here due to space limitations. Excellent comprehensive effects can be achieved within the range of hydroxyl content > 6% in the polyhydroxy compounds given in this application. The inventors have studied and speculated that due to the hydrophilicity of hydroxyl groups, when the foamed polypropylene composition is mixed with a foaming agent for injection molding to prepare a foamed part, the foaming agent added during the injection molding process will decompose to produce carbon dioxide and water. Under the pressure of the injection molding machine screw, the decomposed carbon dioxide is easily dissolved in water. Therefore, by adjusting the hydrophilic hydroxyl content, the dispersion and distribution of carbon dioxide in the melt can be adjusted, thereby affecting the foaming effect.

[0041] In some embodiments, the polyol has a hydroxyl content of 9.4-11.8%. The inventors have found that when the polyol has a hydroxyl content of 9.4-11.8%, the overall effect of the obtained product is even better.

[0042] In some embodiments, after the melt elasticity regulator is mixed with the PP resin, the viscoelastic temperature of the PP resin may be increased by 31-36°C, 35-45°C, 25-45°C, 25-35°C, etc., or increased by any point value or a range value consisting of any two points above 20°C, such as 20°C, 22°C, 25°C, 28°C, 30°C, 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, 48°C, 50°C, 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. As long as the selected melt elasticity regulator increases the viscoelastic temperature of the PP resin by more than 20°C after mixing with the PP resin, excellent results can be achieved. The inventors have studied and speculated that when a foamed polypropylene composition is mixed with a foaming agent and used to prepare foamed parts, the melt strength of the material is significantly improved at the viscoelastic temperature transition point of the melt, which is beneficial to limiting the growth of bubbles. When the foaming agent is fully dispersed, limiting the growth of bubbles is beneficial to reducing the bubble size and inhibiting bubble merging. Therefore, the extent to which the viscoelastic temperature of the PP resin increases after the selected melt elasticity regulator is mixed with the PP resin will affect the foaming effect.

[0043] In some embodiments, the melt elasticity modifier increases the viscoelastic temperature of the PP resin by 31-36° C. after being mixed with the PP resin. Within this range of increase, the overall effect of the obtained product is more excellent.

[0044] In some embodiments, the melt mass flow rate of the PP resin at 230°C and 2.16 kg may be 60-100 g / 10 min, 60-80 g / 10 min, 60-90 g / 10 min, etc., or may be any point value of 55-105 g / 10 min or a range value consisting of any two points, such as 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., and a range value consisting of any two points of the above values. Due to space limitations, they are not listed here one by one; excellent results can be achieved within the range of 55-105 g / 10 min given in this application.

[0045] In some embodiments, the melt flow rate of the PP resin at 230° C. and 2.16 kg is 80-90 g / 10 min. Within this melt flow rate range, the overall effect of the obtained product is more excellent.

[0046] In some embodiments, the mass percentage of the PP resin in the foamed polypropylene composition is not less than 65%.

[0047] In some embodiments, the melt elasticity modifier is a sorbitol compound.

[0048] The inventors have found that when the melt elasticity regulator selected is a sorbitol compound, the size of the bubbles can be better reduced and the maximum weight loss rate can be increased.

[0049] In some embodiments, the high specific surface area filler is selected from at least one of titanium dioxide, fumed alumina, silicon dioxide, organic clay, and porous silica gel.

[0050] In some embodiments, the D50 particle size of the high specific surface area filler is ≤50 nm. The D50 particle size of the high specific surface area filler is measured by a laser particle size analyzer, such as ISO 13320-1-1999.

[0051] In some embodiments, the polyol is selected from at least one of glyceryl monostearate, sorbitan monostearate, sorbitan monolaurate, oleic acid diethanolamide, and polyethylene glycol.

[0052] In some embodiments, the sorbitol compound is at least one selected from 1,3-2,4-bis(p-methylbenzylidene)sorbitol and 1,3-2,4-bis(3,4-dimethylbenzylidene)sorbitol.

[0053] The inventors have found that when high specific area fillers, polyhydroxy compounds, and sorbitol compounds are further selected as the above-mentioned substances, the comprehensive effect of the obtained product is even better.

[0054] In some embodiments, the raw materials for preparing the foamed polypropylene composition further include 0-20 parts of filler, 0-20 parts of toughening agent, and 0-1 part of auxiliary agent.

[0055] In some embodiments, the filler is selected from at least one of talc, calcium carbonate, barium sulfate, and glass fiber;

[0056] And / or, the toughening agent is selected from at least one of POE, SEBS, and EPDM;

[0057] And / or, the auxiliary agent is selected from at least one of an antioxidant and a light stabilizer.

[0058] In some embodiments, the antioxidant may be at least one of a hindered phenol antioxidant and a phosphite antioxidant. In some embodiments, the light stabilizer may be a hindered amine light stabilizer.

[0059] The second aspect of the present application provides a method for preparing the foamed polypropylene composition, comprising the following steps: weighing the dried raw materials, mixing them, and then melt-kneading them, followed by extrusion and granulation to obtain the foamed polypropylene composition.

[0060] In some embodiments, the melt mixing temperature is 200-210° C., and the screw speed is 350-450 r / min.

[0061] A third aspect of the present application provides a foamed article, which is prepared using raw materials including the foamed polypropylene composition described in the present application.

[0062] In some embodiments, the foamed article is prepared by mixing the foamed polypropylene composition described herein with a foaming agent. In some embodiments, the foaming agent comprises at least one of sodium bicarbonate, azodicarbonamide, and sulfonylhydrazide. In some embodiments, the foaming agent can also be added in the form of a masterbatch, with the mass percentage of the foaming agent in the masterbatch being 15-30%, based on the mass of the foaming agent masterbatch.

[0063] In some embodiments, the mass percentage of the foaming agent is 0.2-3% based on the mass of the foamed article. In some embodiments, the mass percentage of the foaming agent is 0.2-2% or 0.25-1% based on the mass of the foamed article.

[0064] The fourth aspect of the present application provides application of the foamed polypropylene composition in the automotive field.

[0065] In some embodiments, the foamed polypropylene composition can be used to prepare automobile door panels and instrument panels.

[0066] It is understandable that the present application also discloses a raw material composition for preparing the foamed polypropylene composition described in any of the above embodiments.

[0067] 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.

[0068] Unless otherwise specified, the reagents, methods and equipment used in this application are conventional reagents, methods and equipment in the art.

[0069] PP-1: K7780, melt index 80g / 10min, Yanshan Petrochemical;

[0070] PP-2: melt index (i.e., melt mass flow rate; in this example, the melt index was measured at 230°C, 2.16 kg) 90 g / 10 min. It was prepared by blending K7780 and BX3920 in a 1:1 mass ratio and extruding. It was homemade.

[0071] PP-3: BX3900, melt index 60g / 10min, SK, South Korea;

[0072] PP-4: BX3920, melt index 100g / 10min, South Korea SK;

[0073] PP-5: M1700, melt index 40g / 10min, LG, South Korea;

[0074] PP-6: PP7945E1, melt index 120g / 10min, ExxonMobil;

[0075] High specific surface area filler 1: Titanium dioxide, TTO-55D, Japan Ishihara, average specific surface area of ​​75m 2 / g;

[0076] High specific surface area filler 2: titanium dioxide, PGNR-318G, Pangang vanadium titanium, average specific surface area of ​​46m 2 / g;

[0077] High specific surface area filler 3: Fumed alumina, Alu C, Evonik Degussa, average specific surface area of ​​85m 2 / g;

[0078] High specific surface area filler 4: titanium dioxide, CR-350, Pangang vanadium titanium, average specific surface area of ​​15m 2 / g;

[0079] Polyol 1: glyceryl monostearate, hydroxyl content 9.4%, commercially available;

[0080] Polyol 2: sorbitan monostearate, hydroxyl content 11.8%, commercially available;

[0081] Polyol 3: sorbitan monolaurate, hydroxyl content 14.7%, commercially available;

[0082] Polyol 4: glyceryl distearate, hydroxyl content 4.7%, commercially available;

[0083] Melt elasticity regulator 1: 1,3-2,4-bis(3,4-dimethylbenzylidene) sorbitol, NA-98, Chenghe Technology, can increase the viscoelastic transition temperature of polypropylene by 36°C;

[0084] Melt elasticity regulator 2: A mixture of NA98 and NX8000K in a mass ratio of NA98:NX8000K=3:2 can increase the viscoelastic transition temperature of polypropylene by 31°C;

[0085] Melt elasticity modifier 3: 1,3-2,4-di(p-methylbenzylidene) sorbitol, 3940, Milliken, can increase the viscoelastic transition temperature of PP by 45°C;

[0086] Melt elasticity regulator 4: A mixture of NA98 and NX8000K in a mass ratio of NA98:NX8000K=3:7 can increase the viscoelastic transition temperature of polypropylene by 25°C;

[0087] Melt elasticity modifier 5: 1,3-2,4-di(4-propylbenzylidene)-1-propyl sorbitol, NX8000K, Milliken, can increase the viscoelastic transition temperature of polypropylene by 15°C;

[0088] Toughener: POE, ENGAGE 8137, Dow Chemical;

[0089] Filler: talc, TYT-777A, Beihai Group;

[0090] Antioxidant: Antioxidant 1010 and antioxidant 168 were mixed in a mass ratio of 1:1 and were commercially available;

[0091] Light stabilizer: UV-3853, 2,2,6,6-tetramethyl-4-piperidinyl stearate, commercially available;

[0092] The toughening agent, filler, antioxidant and light stabilizer used in the parallel experiments of the examples and comparative examples were consistent.

[0093] The viscoelastic temperature test method is as follows: a melt elasticity modifier is added to PP resin BX3920 (manufacturer: sk, South Korea) at a ratio of 0.5wt%, and the modified plastic particles are obtained by screw extrusion granulation. The particles are then hot-pressed into 1mm templates at 190°C, and 25mm discs are cut out for rotational rheology testing. The rotational rheometer test parameters are as follows: 25mm plate 1mm spacing, strain 2%, frequency 1rad / s, test temperature 200°C-120°C, and cooling rate -5°C / min.

[0094] Examples 1-14 and Comparative Examples 1-9

[0095] The component contents (parts by weight) of the examples and comparative examples of the present application are shown in Table 1-2;

[0096] Table 1

[0097] Table 2

[0098] The preparation methods of Examples 1-14 and Comparative Examples 1-9 are:

[0099] The dried raw materials are weighed, mixed, and then melt-kneaded at 200-210° C. with a screw speed of 400 rpm, followed by extrusion and granulation to obtain a foamed polypropylene composition.

[0100] Effect Examples

[0101] The present application effect example verifies the performance of the products prepared in Examples 1-14 and Comparative Examples 1-9; test samples are prepared by injection molding according to the corresponding standards, specifically: the compositions prepared in Examples and Comparative Examples are subjected to a secondary mold injection molding experiment, specifically, the products prepared in Examples 1-14 and Comparative Examples 1-9 are mixed with a foaming agent masterbatch (sodium bicarbonate masterbatch, EE25C, the mass percentage of sodium bicarbonate in the masterbatch is 18%, Japan Yonghe) for foaming, wherein the addition amount of the foaming agent masterbatch is 2wt%, the foaming process is: 200°C, injection speed 140mm / s, delayed mold opening time 0.5S, secondary mold opening speed 4mm / s, the original size of the injection molding sample is 100mm*100mm*1.8mm; then the test is carried out, and the test items include the following aspects:

[0102] 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;

[0103] 2. Cell size: Cut a 50mm*50mm*2.57mm specimen from the middle position perpendicular to the injection flow direction, fracture it in liquid nitrogen, take a picture with a scanning electron microscope, and perform statistical calculations with Image-Pro.

[0104] 3. Melt mass flow rate (before foaming): refer to ISO1133-2005, test conditions: 230℃, 2.16KG;

[0105] The test results are shown in Table 3;

[0106] Table 3

[0107] As can be seen from Table 3, when the technical solution of the present application is adopted, the obtained product has an excellent comprehensive effect, not only meeting the requirements of excellent melt mass flow rate, but also having a lower cell size and a larger maximum weight loss rate. Specifically, the melt index of the obtained product is between 35.3-68.2 g / 10 min, that is, it can ensure the target of a melt index greater than 30 g / 10 min, a maximum weight loss rate of more than 41.6%, and a cell size of less than 116.5 μm.

[0108] It can be seen from Example 1 and Comparative Examples 1-4 that the high specific surface area filler, polyol and melt elasticity modifier in the composition are indispensable, and an excellent comprehensive effect can only be achieved when the three are added simultaneously. When any one of the high specific surface area filler, polyol and melt elasticity modifier is missing in Comparative Examples 1-4, or none of the three are added, the pore size of the products obtained in Comparative Examples 1-4 increases by 44.18-121.70% compared with Example 1; and when no high specific surface area filler is added in Comparative Example 1, the maximum weight loss rate of the obtained product also decreases significantly, by 29.65% compared with Example 1; when no high specific surface area filler, polyol and melt elasticity modifier are added in Comparative Example 4, the maximum weight loss rate of the obtained product decreases significantly, by 36.83% compared with Example 1.

[0109] It can be seen from Example 1, Examples 5-7 and Comparative Examples 5-6 that the melt index of the PP resin not only affects the melt index of the product, but also affects the foaming performance of the product. When the melt index of the PP resin is further selected to be 80-90 g / 10 min, the comprehensive effect of the obtained product is better. Specifically, the melt index of the obtained product is above 42.8 g / 10 min, the maximum weight loss rate is above 53.1%, and the pore size is below 98.5 μm. When the melt index of the PP resin used in Comparative Example 5 is too low, the melt index of the obtained product is also below 30 g / 10 min, which cannot meet the target of a melt index greater than 30 g / 10 min, and the pore size of the obtained product is also significantly increased, which is 77.18% higher than that of Example 1. When the melt index of the PP resin used in Comparative Example 6 is too high, the pore size of the obtained product is significantly increased, which is 56.26% higher than that of Example 1.

[0110] It can be seen from Example 1, Examples 8-9 and Comparative Example 7 that the selection of the specific surface area of ​​the high specific surface area filler will also affect the performance of the product. When the specific surface area of ​​the high specific surface area filler is further selected to be 46-75m 2 / g, the comprehensive effect of the obtained product is better. Specifically, the melt index of the obtained product is above 41.7g / 10min, the maximum weight loss rate is above 49.8%, and the pore size is below 96.5μm. When the specific surface area of ​​the high specific surface area filler used in Comparative Example 7 is too low, the maximum weight loss rate of the obtained product decreases by 29.65% compared with Example 1, and the pore size increases by 40.94%.

[0111] It can be seen from Example 1, Examples 10-11 and Comparative Example 8 that the hydroxyl content in the polyol will also affect the performance of the product. When the hydroxyl content in the polyol is further selected to be 9.4-11.8%, the overall effect of the obtained product is better. Specifically, the melt index of the obtained product is above 40.8 g / 10 min, the maximum weight loss rate is above 52.3%, and the pore size is below 97.3 μm. When the hydroxyl content in Comparative Example 8 is too low, the pore size of the obtained product is increased by 72.60% compared with Example 1.

[0112] It can be seen from Example 1, Examples 12-14 and Comparative Example 9 that the selection of a melt elasticity modifier will affect the performance of the product. When the melt elasticity modifier is further selected so that the viscoelastic transition temperature of the polypropylene is between 31°C and 36°C, the overall effect of the obtained product is better. Specifically, the melt index of the obtained product is above 42.5g / 10min, the maximum weight loss rate is above 52.4%, and the pore size is below 95.1μm. When the melt elasticity modifier selected in Comparative Example 9 cannot make the viscoelastic temperature transition of the PP resin by more than 20°C, the maximum weight loss rate of the obtained product shows a downward trend compared with Example 1, and the pore size increases significantly, with an increase of 81.66%.

[0113] 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 composition, characterized in that The raw materials for preparing the foamed polypropylene composition include the following components in parts by weight: 52-98 parts of polypropylene (PP) resin, 0.3-3.2 parts of high specific surface area filler, 0.3-2.2 parts of polyhydroxy compound, and 0.3-2.2 parts of melt elasticity regulator; The average specific surface area of ​​the high specific surface area filler is greater than 40 m 2 / g; The hydroxyl content of the polyhydroxy compound is greater than 6%; After the melt elasticity regulator is mixed with the PP resin, the viscoelastic temperature of the PP resin increases by more than 20°C; The melt mass flow rate of the PP resin at 230° C. and 2.16 kg is 55-105 g / 10 min.

2. The foamed polypropylene composition according to claim 1, characterized in that The average specific surface area of ​​the high surface area filler is 46-75m 2 / g; and / or, the polyol has a hydroxyl content of 9.4-11.8%; and / or, the melt elasticity modifier increases the viscoelastic temperature of the PP resin by 31-36° C. after being mixed with the PP resin; And / or, the melt mass flow rate of the PP resin at 230° C. and 2.16 kg is 80-90 g / 10 min.

3. The foamed polypropylene composition according to claim 1, characterized in that The melt elasticity regulator is a sorbitol compound; And / or, the high specific surface filler is selected from at least one of titanium dioxide, fumed alumina, porous silica gel, silicon dioxide, and organic clay; And / or, the polyhydroxy compound is at least one selected from glyceryl monostearate, sorbitan monostearate, sorbitan monolaurate, oleic acid diethanolamide, and polyethylene glycol.

4. The foamed polypropylene composition according to claim 3, characterized in that The sorbitol compound is selected from at least one of 1,3-2,4-di(p-methylbenzylidene)sorbitol and 1,3-2,4-di(3,4-dimethylbenzylidene)sorbitol.

5. The foamed polypropylene composition according to claim 1, characterized in that The raw materials for preparing the foamed polypropylene composition further include the following components in parts by weight: 0-20 parts of filler, 0-20 parts of toughening agent, and 0-1 part of auxiliary agent.

6. The foamed polypropylene composition according to claim 5, characterized in that: The filler is selected from at least one of talc, calcium carbonate, barium sulfate and glass fiber; And / or, the toughening agent is selected from at least one of POE (polyolefin elastomer), SEBS (styrene-ethylene-butylene-styrene block copolymer), and EPDM (ethylene propylene diene monomer rubber); And / or, the auxiliary agent is selected from at least one of an antioxidant and a light stabilizer.

7. The method for preparing the foamed polypropylene composition according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: weighing the dried raw materials, mixing them, melting and kneading them, and then extruding and granulating them to obtain a foamed polypropylene composition.

8. A foamed article, characterized in that: The foamed article is obtained by foaming the foamed polypropylene composition according to any one of claims 1 to 6.

9. Use of the foamed polypropylene composition according to any one of claims 1 to 6 in the automotive field.

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