Low-temperature impact-resistant self-reinforced polypropylene bionic composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of bionic composite materials, in particular to a low-temperature impact-resistant self-reinforced polypropylene bionic composite material as well as a preparation method and application thereof. The low-temperature impact-resistant self-reinforced polypropylene bionic composite material is prepared from n layers of polypropylene braided fabrics, n is larger than or equal to 4, and the low-temperature impact-resistant self-reinforced polypropylene bionic composite material is of a corrugated layer-shaped horn-like structure The polypropylene braided fabric is obtained by weaving flat filaments, and each flat filament is provided with a skin layer, a core layer and a skin layer structure. The whole structure of the polypropylene bionic composite material is made of a polypropylene material, the core layer of the polypropylene flat filament is used as a reinforcement body, the skin layer of the polypropylene flat filament is used as a matrix to bond each flat filament and each structural layer, the whole structure recovery of the composite material can be realized, the recovery difficulty of the composite material is obviously reduced, and the material reuse rate is effectively improved; the good interface and interlayer bonding of the self-reinforced polypropylene composite material is realized, and the low-temperature impact resistance is remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bionic composite materials, and particularly to a low-temperature impact-resistant self-reinforced polypropylene bionic composite material, a preparation method thereof, and an application thereof. Background Art

[0002] Polypropylene is favored by all walks of life due to its light weight, high strength, chemical resistance, and good processing performance, and is widely used in fields such as packaging materials, automotive parts, building materials, sports equipment, textiles, household appliances, and industrial equipment. However, due to the regular molecular structure of polypropylene and the weak molecular chain movement ability, its resistance to cracking and impact resistance are poor. Especially in a low-temperature environment, polypropylene becomes brittle, and its impact resistance is significantly reduced, which greatly limits its use in cold environments. In addition, the surface hardness of polypropylene is lower than that of other materials, resulting in poor scratch resistance and difficulty in meeting the requirements of easy wear of components during use.

[0003] The structure of natural ox horns provides a reference idea for improving the performance of composite materials. Ox horns have a wavy lamellar structure. Each lamella is composed of keratin fibers tightly arranged, and the lamellae and keratin fibers are tightly bonded through chemical bonds or van der Waals forces, mineral deposition, and the surrounding of the intercellular matrix. The above structure enables ox horns to have the characteristics of high strength and high toughness, and helps to resist friction and wear. Based on the structural characteristics of "ox horns", a polypropylene laminated composite material with a corrugated layered structure is designed, which is composed of multiple layers of polypropylene sheets bonded together to improve the low-temperature impact resistance and scratch resistance of the composite material.

[0004] With the improvement of global environmental awareness, governments of various countries have introduced a series of policies to promote the recycling of plastic waste. As a widely used plastic material, it is particularly important to realize the recycling of polypropylene. Self-reinforced composite materials, also known as single-polymer composite materials, were first proposed by Capiati and Porter of the University of Leeds in the UK in 1975. Existing self-reinforced composite materials include polyethylene, polypropylene, polyethylene terephthalate, polyamide, polylactic acid, etc. Due to the advantage of low cost of polypropylene, self-reinforced polypropylene materials and their products are the main materials in the research field of self-reinforced composite materials.

[0005] Commercially successful self-reinforced polypropylene composite materials abroad include the patented products of (CN 1826213A) of British Technology Group International Limited and the patented products of (CN101326047A) of Netherlands Lanxess Reinforced Plastics B.V. They are prepared by the direct hot pressing method of polypropylene fibers. However, the processing temperature range is extremely narrow, which easily leads to excessive melting of the fibers and loss of the reinforcing effect; Prepared by the hot pressing method of a co-extruded belt fabric with an ABA structure. The two layers of A are propylene copolymers with a melting point of 135°C, and the fabric is prepared by hot pressing at 145°C. However, the bonding interface strength between the reinforcing fibers and the matrix of this material is poor, and delamination occurs under the action of rapid impact force, resulting in wrinkles and softening at the wheel corners of the material, and even internal damage.

[0006] For the two invention patents CN105563976A and CN107972343A published by Sinopec Corporation in China for self-reinforced polypropylene composites, the former discloses that the outer layer is a low-melting-point random copolymer polypropylene, and the latter further defines the molecular weights of the core layer and the surface layer polypropylene. The surface layers of both use a copolymer polypropylene with a melting point close to that of layer A, and the prepared self-reinforced polypropylene composites have problems similar to those.

[0007] In summary, the existing self-reinforced polypropylene composites have technical problems such as poor bonding between the reinforcing fiber and the matrix, poor interlayer bonding between polypropylene layers, and poor impact resistance. Using a new skin material and a bionic method to solve the above technical problems is the main innovation point of the present invention. Summary of the Invention

[0008] To solve the above problems, the present invention provides a low-temperature impact-resistant self-reinforced polypropylene bionic composite material, its preparation method and application. The entire structure of the polypropylene bionic composite material of the present invention uses polypropylene-based materials. The core layer of polypropylene flat filaments is used as the reinforcement, and at the same time, the skin layer of polypropylene flat filaments is used as the matrix to bond each flat filament and each structural layer, which can realize the full-structure recycling of the composite material, significantly reduce its recycling difficulty, effectively improve the material reuse rate, and achieve good interfacial and interlayer bonding of the self-reinforced polypropylene composite material, as well as a significant improvement in low-temperature impact resistance.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] The present invention provides a low-temperature impact-resistant self-reinforced polypropylene bionic composite material, which is prepared from n layers of polypropylene woven fabrics, n≥4, and has a corrugated layer-like "ox horn" structure;

[0011] The polypropylene woven fabric is woven from flat filaments, and the flat filaments have a skin layer, a core layer and a skin layer structure;

[0012] The components of the core layer include a mixture of isotactic homopolypropylene and block copolymer polypropylene, a nucleating agent and a colorant, and the mass ratio of the mixture of isotactic homopolypropylene and block copolymer polypropylene, the nucleating agent and the colorant is 90-99:1-5:0-5;

[0013] The mixture of isotactic polypropylene and block copolymer polypropylene is composed of isotactic polypropylene and block copolymer polypropylene mixed in a mass ratio of 8-10:0-2;

[0014] The isotactic polypropylene includes isotactic polypropylene T30S and / or isotactic polypropylene F401;

[0015] The block copolymer polypropylene includes propylene-ethylene block copolymer polypropylene CF330 and / or propylene-ethylene block copolymer polypropylene 700R;

[0016] The components of the skin layer are a mixture of random copolymer polypropylene and propylene-based elastomer, a silicone oil lubricating and scratch-resistant agent, and a colorant, and the mass ratio of the mixture of random copolymer polypropylene and propylene-based elastomer, the silicone oil lubricating and scratch-resistant agent, and the colorant is 94-99.9:0.1-1:0-5;

[0017] The mixture of random copolymer polypropylene and propylene-based elastomer is composed of a propylene-ethylene-butene terpolymer and a metallocene-catalyzed polypropylene elastomer mixed in a mass ratio of 8-10:0-2;

[0018] The propylene-ethylene-butene terpolymer includes propylene-ethylene-butene terpolymer 1007;

[0019] The metallocene-catalyzed polypropylene elastomer includes metallocene-catalyzed polypropylene elastomer Vistamaxx6000 or 6102;

[0020] The mass ratio of the core layer to the skin layer is 70-90:10-30, and the skin layers on both sides of the core layer are of equal mass.

[0021] Preferably, the thickness of the polypropylene fabric is 0.1-0.2 mm, and the grammage is 210-270 g / m 2 .

[0022] Preferably, the width of the flat filament is 1.5-2.5 mm, the thickness is 0.04-0.06 mm, and the tensile modulus is not less than 10 GPa.

[0023] Preferably, the components of the nucleating agent include a β-nucleating agent and polypropylene particles, or calcium carbonate and polypropylene particles;

[0024] The β-nucleating agent includes calcium stearate, and the mass ratio of the β-nucleating agent to the polypropylene particles is 5:95;

[0025] The mass ratio of the calcium carbonate to the polypropylene particles is 5:95;

[0026] The preparation method of the nucleating agent includes: adding the β nucleating agent or calcium carbonate to polypropylene particles and melt-extruding them in a screw at a temperature of 200 °C, and then pelletizing;

[0027] The components of the colorant include pigments and polypropylene particles, and the pigments include inorganic pigments and organic pigments;

[0028] The mass ratio of the pigment to the polypropylene particles is 5:95;

[0029] The preparation method of the colorant includes: melt-extruding the pigment and polypropylene particles in a screw at a temperature of 200 °C, and then pelletizing;

[0030] The components of the silicone oil lubricating and scratch-resistant agent include polydimethylsiloxane and polypropylene particles, and the mass ratio of polydimethylsiloxane to polypropylene particles is 5:95;

[0031] The preparation method of the silicone oil lubricating and scratch-resistant agent includes: melt-extruding the polydimethylsiloxane and polypropylene particles in a screw at a temperature of 200 °C, and then pelletizing;

[0032] The grade of the polypropylene particles is 1007.

[0033] The present invention also provides a preparation method of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material described in the above technical solution, including the following steps:

[0034] 1) According to the skin layer, core layer and skin layer structure of the flat yarn, co-extrude the components, cool to form a film, cut into filaments, stretch, heat-set and cool to obtain flat yarns, and the stretching ratio is not less than 10;

[0035] 2) Weave the flat yarns obtained in step 1) in a warp and weft interlacing manner to form a polypropylene woven fabric with a plain or twill weave;

[0036] 3) Stack n layers of the polypropylene woven fabrics obtained in step 2) and press them by a composite process to obtain a low-temperature impact-resistant self-reinforced polypropylene bionic composite material.

[0037] Preferably, the temperature of the co-extrusion in step 1) is 230-250 °C;

[0038] The cooling to form a film is that the extrudate is cooled by water at 25 °C to form a three-layer co-extruded film with a thickness of 0.20-0.30 mm and having a "skin layer-core layer-skin layer" structure;

[0039] The cutting into filaments is to cut the three-layer co-extruded film into filaments with a width of 2-5 mm;

[0040] The stretching conditions include: temperature of 120 - 140°C, drawing rate of 4 - 6 m / min, draft rate of 40 - 70 m / min, and draw ratio of more than 10 times;

[0041] The heat setting temperature is 60 - 70°C;

[0042] The cooling temperature is 20 - 30°C.

[0043] Preferably, the conditions of the composite process in step 3) include: heating temperature of 130 - 140°C, speed of 2 m / min, and cooling temperature of 20 - 50°C.

[0044] The present invention also provides the application of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material described in the above technical solution in improving the tensile strength of polypropylene composite materials.

[0045] The present invention also provides the application of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material described in the above technical solution in improving the tensile modulus of polypropylene composite materials.

[0046] The present invention also provides the application of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material described in the above technical solution in improving the impact strength of polypropylene composite materials.

[0047] The beneficial effects of the present invention:

[0048] The present invention draws on the structural characteristics of natural horns with high strength, high toughness, anti-friction and anti-wear properties, and designs and prepares a self-reinforced polypropylene composite material with a corrugated layered structure based on the mutual bonding of multiple polypropylene sheets. Among them, the skin layer of the self-reinforced polypropylene composite material uses a mixture of random copolymerized polypropylene and propylene-based elastomer, which has a lower melting point than the 135 - 140°C copolymerized polypropylene used in the skin layer material of the prior art, significantly improving the interfacial adhesion strength between the reinforcing fiber and the matrix and the interlayer adhesion of polypropylene layers, and solving the problem of wrinkling and softening at the corners of structural parts during subsequent pressing and forming. At the same time, due to the improvement of the bonding performance, the impact toughness of the polypropylene composite material, especially the low-temperature impact resistance, is significantly improved. In addition, aiming at the problems of poor scratch resistance and easy wear on the surface of polypropylene materials, the present invention is solved by adding a small amount of scratch-resistant agent to the skin layer material. Since all structures of the polypropylene composite material of the present invention use polypropylene-based materials, the mass percentage of polypropylene exceeds 99.2%, and other additives play functions such as coloring, improving crystallization or scratch resistance, without affecting the reuse of polypropylene materials. Description of the Drawings

[0049] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the embodiments.

[0050] Figure 1 A self-reinforced polypropylene composite material (10) with a corrugated layered structure, which is pressed from a polypropylene fabric (20);

[0051] Figure 2 A fabric (20) with twill or plain weave, which is woven from polypropylene flat filaments (30) in warp and weft directions;

[0052] Figure 3 They are respectively in the form of twill weave (21) and plain weave (22) of the fabric (20);

[0053] Figure 4 A flat filament (30) obtained by stretching a polypropylene coextruded film with a "skin-core-skin" structure;

[0054] Figure 5 A physical picture of the self-reinforced polypropylene composite material (30) for performance testing;

[0055] Figure 6 A physical picture of the 8-layer composite material after tensile property and impact property tests. Specific implementation mode

[0056] The present invention provides a low-temperature impact-resistant self-reinforced polypropylene bionic composite material, which is prepared from an n-layer polypropylene woven fabric, n≥4, and has a corrugated layered "ox horn" structure, as Figure 1 shown; the polypropylene woven fabric is woven from flat filaments, and the woven fabric and its tissue form are respectively shown in Figure 2 、 Figure 3 ; the flat filament has a skin layer, a core layer and a skin layer structure, as Figure 4As shown; the components of the core layer include a mixture of isotactic polypropylene and block copolymer polypropylene, a nucleating agent, and a colorant, and the mass ratio of the isotactic polypropylene and block copolymer polypropylene mixture, the nucleating agent, and the colorant is 90-99:1-5:0-5; the mixture of isotactic polypropylene and block copolymer polypropylene is composed of isotactic polypropylene and block copolymer polypropylene mixed in a mass ratio of 8-10:0-2; the isotactic polypropylene includes isotactic polypropylene T30S and / or isotactic polypropylene F401; the block copolymer polypropylene includes block copolymer polypropylene CF330 and / or block copolymer polypropylene 700R; the components of the skin layer are a mixture of random copolymer polypropylene and propylene-based elastomer, a silicone oil lubricating and scratch-resistant agent, and a colorant, and the mass ratio of the random copolymer polypropylene and propylene-based elastomer mixture, the silicone oil lubricating and scratch-resistant agent, and the colorant is 94-99.9:0.1-1:0-5; the mixture of random copolymer polypropylene and propylene-based elastomer is composed of a propylene-ethylene-butene terpolymer and a metallocene-catalyzed polypropylene elastomer mixed in a mass ratio of 8-10:0-2; the propylene-ethylene-butene terpolymer includes propylene-ethylene-butene terpolymer 1007; the metallocene-catalyzed polypropylene elastomer includes metallocene-catalyzed polypropylene elastomer Vistamaxx 6000 or 6102; the mass ratio of the core layer to the skin layer is 70-90:10-30, and the skin layers on both sides of the core layer are of equal mass.

[0057] In the present invention, the melting point of the isotactic polypropylene is 160-180 °C, and the isotactic index is not less than 95%. In the present invention, the melting point of the propylene-ethylene-butene terpolymer is not higher than 135 °C. The above-mentioned polypropylene types in the present invention are from conventional commercially available grades such as Sinopec, Hanwha Group, ExxonMobil, and Dow Chemical.

[0058] In the present invention, the thickness of the polypropylene fabric is preferably 0.1-0.2 mm, and the grammage is preferably 210-270 g / m 2。In the present invention, the width of the flat filament is preferably 1.5 - 2.5 mm, the thickness is preferably 0.04 - 0.06 mm, and the tensile modulus is preferably not less than 10 GPa. In the present invention, the components of the nucleating agent preferably include a β-nucleating agent and polypropylene particles, or calcium carbonate and polypropylene particles; the β-nucleating agent preferably includes calcium stearate, and the mass ratio of the β-nucleating agent to the polypropylene particles is preferably 5:95; the mass ratio of the calcium carbonate to the polypropylene particles is preferably 5:95; the preparation method of the nucleating agent preferably includes: adding the β-nucleating agent or calcium carbonate to the polypropylene particles and melt-extruding them in a screw at a temperature of 200°C, and then pelletizing. The particles are irregular particles in the shape of a sphere, ellipsoid or cylinder with a size between 4 - 6 mm in any direction. In the present invention, the components of the colorant preferably include a pigment and polypropylene particles, and the pigment includes an inorganic pigment and an organic pigment;

[0059] The mass ratio of the pigment to the polypropylene particles is preferably 5:95; the preparation method of the colorant preferably includes: melt-extruding the pigment and the polypropylene particles in a screw at a temperature of 200°C, and then pelletizing. The particles are irregular particles in the shape of a sphere, ellipsoid or cylinder with a size between 4 - 6 mm in any direction. The present invention has no special limitation on the types of organic pigments and inorganic pigments. In the present invention, the components of the silicone oil lubricating and scratch-resistant agent preferably include polydimethylsiloxane and polypropylene particles, and the mass ratio of the polydimethylsiloxane to the polypropylene particles is preferably 5:95; the preparation method of the silicone oil lubricating and scratch-resistant agent preferably includes: melt-extruding the polydimethylsiloxane and the polypropylene particles in a screw at a temperature of 200°C, and then pelletizing. The particles are irregular particles in the shape of a sphere, ellipsoid or cylinder with a size between 4 - 6 mm in any direction. In the present invention, the grade of the polypropylene particles is preferably 1007.

[0060] The present invention also provides a preparation method of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to the above technical solution, including the following steps:

[0061] 1) According to the skin layer, core layer and skin layer structure of the flat filament, the components are processed through steps of co-extrusion, cooling to form a film, cutting into filaments, stretching, heat setting and cooling to obtain a flat filament, and the stretching ratio is not less than 10;

[0062] 2) The flat filament obtained in step 1) is woven into a polypropylene woven fabric with a plain or twill weave by means of warp and weft interlacing;

[0063] 3) Stacking n layers of the polypropylene woven fabric obtained in step 2) and pressing them through a composite process to obtain the low-temperature impact-resistant self-reinforced polypropylene bionic composite material.

[0064] According to the skin layer, core layer and skin layer structure of the flat yarn, the components are processed by co-extrusion, stretching and cooling to obtain flat yarn, and the stretching ratio is not less than 10. In the present invention, the temperature of the co-extrusion is preferably 230-250 °C. In the present invention, the cooling and film forming is that the extrudate is water-cooled at 25 °C to form a three-layer co-extruded film with a thickness of 0.20-0.30 mm. In the present invention, the wire cutting is to cut the co-extruded film into wire strips with a width of 2-5 mm. In the present invention, the temperature of the stretching is 120-140 °C, the traction rate is 4-6 m / min, the drawing rate is 40-70 m / min, and the stretching ratio is more than 10 times. In the present invention, the temperature of the heat setting is 60-70 °C. In the present invention, the temperature of the cooling is preferably 20-30 °C.

[0065] The flat yarn obtained in the present invention is woven into a polypropylene woven fabric with a plain or twill weave by means of warp and weft interweaving. The present invention has no special limitation on the method of weaving in the warp and weft directions, and it can be woven by using a conventional warp and weft weaving method.

[0066] The present invention stacks n layers of polypropylene woven fabrics and presses them through a composite process to obtain a low-temperature impact-resistant self-reinforced polypropylene bionic composite material. In the present invention, the conditions of the composite process preferably include: the heating temperature is 130-140 °C, the speed is 2 m / min, and the cooling temperature is 20-50 °C. In the present invention, the polypropylene woven fabric is preferably pressed in a composite machine.

[0067] The present invention also provides the application of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material described in the above technical solution in improving the tensile strength of the polypropylene composite material.

[0068] The present invention also provides the application of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material described in the above technical solution in improving the tensile modulus of the polypropylene composite material.

[0069] The present invention also provides the application of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material described in the above technical solution in improving the impact strength of the polypropylene composite material.

[0070] In order to further illustrate the present invention, the present invention will be described in detail below in conjunction with the embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0071] Example 1

[0072] A low-temperature impact-resistant self-reinforced polypropylene bionic composite material (10):

[0073] The flat yarn (30) is formed by stretching a film that is co-extruded in three layers with a skin-core-skin ratio of 5:90:5 from 90 parts by weight of a high-melting-point polypropylene core layer (31) and 10 parts by weight of a low-melting-point polypropylene skin layer (32) by 10 times. The core layer (31) is composed of 95 parts by weight of isotactic polypropylene homopolymer T30S and 5 parts by weight of a calcium carbonate nucleating agent masterbatch. The skin layer (32) is composed of a mixture of 99 parts by weight of an ethylene-propylene-butene terpolymer 1007 and a metallocene-catalyzed polypropylene elastomer Vistamaxx 6000 in a mass ratio of 8:2, and 1 part by weight of a polydimethylsiloxane silicone lubricant and scratch-resistant agent.

[0074] The components of the calcium carbonate nucleating agent masterbatch are calcium carbonate and polypropylene particles, with a mass ratio of 5:95. At 200 °C, the calcium carbonate and polypropylene particles are melt-blended and extruded in a screw, and then pelletized. The particles are irregular particles in the shape of spheres, ellipsoids or cylinders with a size ranging from 4 to 6 mm in any direction; the grade of the polypropylene particles is 1007.

[0075] The components of the polydimethylsiloxane silicone lubricant and scratch-resistant agent are polydimethylsiloxane and polypropylene particles, with a mass ratio of 5:95. At 200 °C, the polydimethylsiloxane and polypropylene particles are melt-blended and extruded in a screw, and then pelletized. The particles are irregular particles in the shape of spheres, ellipsoids or cylinders with a size ranging from 4 to 6 mm in any direction; the grade of the polypropylene particles is 1007.

[0076] The preparation method of the flat yarn: Use the materials of the core layer (31) and the skin layer (32) to prepare a three-layer co-extruded film with a "skin-core-skin" structure. The co-extrusion temperature is 240 °C, and it is cooled by water at 25 °C to form a film with a thickness of 0.20 mm. The co-extruded film is cut into filaments with a width of 4 mm, and stretched at a stretching temperature of 130 °C, a traction rate of 5.4 m / min, and a draw ratio of 55 m / min, and heat-set at 70 °C and cooled at 25 °C to obtain the flat yarn (30). The stretching ratio is 10 times. The width of the flat yarn is 1.5 - 2.5 mm, with an average value of 2.0 mm, and the thickness is 0.04 - 0.06 mm, with an average value of 0.05 mm.

[0077] Examples 2 - 4 respectively use different stretching ratios and "skin-core-skin" ratios on the basis of Example 1. Example 5 uses a calcium stearate nucleating agent masterbatch on the basis of Example 1. Example 6 uses a carbon black colorant on the basis of Example 1. Examples 7 - 10 respectively use different materials of the high-melting-point polypropylene core layer (31) and the low-melting-point polypropylene skin layer (32) to prepare the flat yarn (30). The specific formulations are shown in Table 1.

[0078] The components of the calcium stearate nucleating agent masterbatch are calcium stearate and polypropylene particles, and the mass ratio is 5:95. The calcium stearate and polypropylene particles are melt blended and extruded in a screw at 200 °C, and then pelletized. The particles are irregular particles in the shape of a sphere, ellipsoid or cylinder with a size between 4-6 mm in any direction; the grade of the polypropylene particles is 1007.

[0079] The components of the carbon black colorant are carbon black and polypropylene particles, and the mass ratio is 5:95. The carbon black and polypropylene particles are melt blended and extruded in a screw at 200 °C, and then pelletized. The particles are irregular particles in the shape of a sphere, ellipsoid or cylinder with a size between 4-6 mm in any direction; the grade of the polypropylene particles is 1007.

[0080] Table 1 Material formula of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material

[0081]

[0082]

[0083] Example 11

[0084] The flat filaments (30) obtained according to the above Examples 1-10 are woven into a fabric (20) with a twill weave (21) or a plain weave (22) by warp and weft weaving, as Figure 3 shown. The multi-layer polypropylene fabric (20) is stacked layer by layer in sequence and molded into a bionic composite material (10) with a "horn-like" structure through a composite process, as Figure 1 shown.

[0085] The fabric (20) woven with the flat filaments prepared in Example 1 is used. Four layers of the fabric (20) are stacked layer by layer in the same warp and weft direction and pressed into a bionic composite material (10) through procedures such as preheating, heating, and cooling by a composite machine, as Figure 5 shown. The setting parameters of the composite machine are: the heating temperature is 135 °C, the roller speed is 2.0 m / min, and the cooling temperature is 20 °C.

[0086] Example 12

[0087] Eight layers of the fabric (20) are thermally compounded according to the method of Example 11 to prepare a bionic composite material (10).

[0088] Example 13

[0089] Ten layers of the fabric (20) are thermally compounded according to the method of Example 11 to prepare a bionic composite material (10).

[0090] Example 14

[0091] The 12-layer fabric (20) was thermally compounded according to the method of Example 11 to prepare the bionic composite material (10).

[0092] Comparative Example 1

[0093] The flat yarn (30) was made by stretching a film formed by three-layer co-extrusion of 90 parts by weight of a high melting point polypropylene core layer (31) and 10 parts by weight of a low melting point polypropylene skin layer (32) in a skin-core-skin ratio of 5:90:5 by 10 times. The core layer (31) was isotactic homopolypropylene T30S, and the skin layer (32) was an ethylene-propylene-butene terpolymer 1007.

[0094] The preparation methods of the flat yarn and the fabric were the same as those in Example 1.

[0095] The 8-layer fabric (20) was stacked layer by layer in the same warp and weft directions, and pressed into the bionic composite material (10) through procedures such as preheating, heating, and cooling by a compounding machine. The set parameters of the compounding machine were a heating temperature of 135 °C, a roller speed of 2.0 m / min, and a cooling temperature of 20 °C.

[0096] Referring to ISO 527-2 "Plastics - Determination of tensile properties", ISO 179-1 "Plastics - Determination of Charpy impact strength", and GB 8808-88 "Test method for peel strength of flexible composite plastic materials", the tensile strength / modulus, notchless impact resistance at normal temperature / low temperature, and interlayer peel force of the composite material (10) were tested respectively. The test results of the physical and mechanical properties of the bionic composite materials prepared in Examples 11-14 and Comparative Example 1 are shown in Table 2.

[0097] The pictures of the specimens after tensile, Charpy impact, and drop hammer impact in Example 12 are shown in Figure 6 .

[0098] Table 2 Test results of the properties of the bionic composite material

[0099]

[0100] From the test results of Examples 11-14, it can be seen that the present invention has prepared a fully-structured polypropylene composite material with good mechanical properties. Compared with the comparative examples, the tensile strength and modulus, impact strength and interlayer peel force of Examples 11-14 have been significantly improved. This is mainly because the skin layer of the composite material in Examples 11-14 uses a mixture of random copolymerized polypropylene with a low melting point (100-130 °C) and an olefin-based elastomer, which has a lower melting point than the random copolymerized polypropylene with a melting point of 130-140 °C used in the skin layer material of the comparative examples, significantly improving the interfacial adhesion strength between the reinforcing fiber and the matrix and the interlayer adhesion between polypropylene layers, and solving the problem of wrinkling and softening at the corners of the structural parts during subsequent pressing and forming. At the same time, due to the improvement of the bonding performance, the impact toughness of the polypropylene composite material has been significantly improved, especially the low-temperature impact resistance. In addition, in the composite material prepared by the present invention using isotactic polypropylene core layer material, random copolymerized polypropylene and metallocene polypropylene skin layer material, nucleating agent / coloring agent polypropylene masterbatch, and a small amount of anti-scratch agent, etc., the proportion of polypropylene is above 99.2%, which can effectively realize the recycling and reuse of the fully-structured material.

[0101] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A low-temperature impact-resistant self-reinforced polypropylene bionic composite material, characterized in that: It is made of n layers of polypropylene braid, n≥4, and has a corrugated layered "horn" structure; The polypropylene braid is woven from flat yarns, and the flat yarns have a structure of a skin layer, a core layer and a skin layer; The components of the core layer include a mixture of isotactic homopolypropylene and block copolymer polypropylene, a nucleating agent and a coloring agent, wherein the mass ratio of the mixture of isotactic homopolypropylene and block copolymer polypropylene, the nucleating agent and the coloring agent is 90-99:1-5:0-5; The isotactic homopolypropylene and block copolymer polypropylene mixture is prepared by mixing isotactic homopolypropylene and block copolymer polypropylene in a mass ratio of 8-10:0-2; The isotactic homopolypropylene includes isotactic homopolypropylene T30S and / or isotactic homopolypropylene F401; The block copolymer polypropylene includes propylene-ethylene block copolymer polypropylene CF330 and / or propylene-ethylene block copolymer polypropylene 700R; The components of the skin layer are a mixture of random copolymerized polypropylene and propylene-based elastomer, a silicone oil lubricating scratch-resistant agent and a colorant, and the mass ratio of the mixture of random copolymerized polypropylene and propylene-based elastomer, silicone oil lubricating scratch-resistant agent and colorant is 94-99.9:0.1-1:0-5; The random copolymer polypropylene and propylene-based elastomer mixture is prepared by mixing propylene-ethylene-butene terpolymer and metallocene-catalyzed polypropylene elastomer in a mass ratio of 8-10:0-2; The propylene-ethylene-butene terpolymer includes propylene-ethylene-butene terpolymer 1007; The metallocene-catalyzed polypropylene elastomer includes metallocene-catalyzed polypropylene elastomer Vistamaxx 6000 or 6102; The mass ratio of the core layer to the skin layer is 70-90:10-30, and the skin layers on both sides of the core layer are of equal mass.

2. The low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to claim 1, characterized in that: The thickness of the polypropylene braid is 0.1-0.2 mm, and the weight is 210-270 g / m 2 .

3. The low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to claim 1, characterized in that: The flat wire has a width of 1.5 to 2.5 mm, a thickness of 0.04 to 0.06 mm, and a tensile modulus of not less than 10 GPa.

4. The low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to claim 1, characterized in that: The components of the nucleating agent include a β-nucleating agent and polypropylene particles, or calcium carbonate and polypropylene particles; The beta nucleating agent includes calcium stearate, and the mass ratio of the beta nucleating agent to the polypropylene particles is 5:95; The mass ratio of the calcium carbonate to the polypropylene particles is 5:95; The preparation method of the nucleating agent comprises: blending and extruding the beta nucleating agent or calcium carbonate with polypropylene particles in a screw at a temperature of 200° C., followed by granulation; The components of the colorant include pigments and polypropylene particles, and the pigments include inorganic pigments and organic pigments; The mass ratio of the pigment to the polypropylene particles is 5:95; The preparation method of the colorant comprises: blending and extruding the pigment and polypropylene particles in a screw at a temperature of 200° C., followed by granulation; The components of the silicone oil lubricated anti-scratch agent include polydimethylsiloxane and polypropylene particles, and the mass ratio of the polydimethylsiloxane to the polypropylene particles is 5:95; The preparation method of the silicone oil lubricated scratch resistant agent comprises: blending and extruding the polydimethylsiloxane and polypropylene particles in a screw at a temperature of 200° C., followed by granulation; The grade of the polypropylene particles is 1007.

5. A method for preparing the low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) according to the skin layer, core layer and skin structure of the flat yarn, the components are subjected to a process of coextrusion, cooling film formation, slitting, stretching, heat setting and cooling to obtain the flat yarn, and the stretching ratio is not less than 10; 2) weaving the flat yarn obtained in step 1) into a polypropylene woven fabric with plain or twill weave by interweaving in warp and weft directions; 3) stacking n layers of polypropylene braided fabrics obtained in step 2) and pressing them through a composite process to obtain a low-temperature impact-resistant self-reinforced polypropylene bionic composite material.

6. The preparation method according to claim 5, characterized in that: The co-extrusion temperature in step 1) is 230-250°C; The cooling film forming is that the extrudate is water-cooled at 25°C to form a three-layer co-extruded film with a thickness of 0.20-0.30 mm and a "skin layer-core layer-skin layer" structure; The slitting is to cut the three-layer co-extruded film into filaments with a width of 2 to 5 mm; The stretching conditions include: a temperature of 120 to 140°C, a pulling rate of 4 to 6 m / min, a drawing rate of 40 to 70 m / min, and a stretching ratio of more than 10 times; The heat setting temperature is 60-70°C; The cooling temperature is 20-30°C.

7. The preparation method according to claim 5, characterized in that: The conditions of the composite process in step 3) include: a heating temperature of 130-140°C, a speed of 2 m / min, and a cooling temperature of 20-50°C.

8. Use of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to any one of claims 1 to 4 in improving the tensile strength of polypropylene composite materials.

9. Use of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to any one of claims 1 to 4 in improving the tensile modulus of polypropylene composite materials.

10. Use of the low-temperature impact-resistant self-reinforced polypropylene bionic composite material according to any one of claims 1 to 4 in improving the impact strength of polypropylene composite materials.

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