Polypropylene sheet and polypropylene fabric and high-strength high-impact polypropylene composite material thereof and its manufacturing method and application

Abstract

This invention relates to the field of polypropylene materials, and discloses a polypropylene sheet, a polypropylene fabric, a high-strength and high-impact polypropylene composite material, its preparation method, and its applications. The polypropylene sheet includes a film layer A containing a polypropylene composition A and a film layer B containing a polypropylene composition B. The film layers B on both sides of film layer A may be the same or different. The polypropylene sheet has a BAB layer structure, with film layers B located on both sides of film layer A. Polypropylene composition A includes homopolymer polypropylene a and impact copolymer polypropylene b. Polypropylene composition B includes random copolymer polypropylene x and a thermal bonding reinforcing agent y. The polypropylene composite material obtained by hot-pressing this polypropylene sheet exhibits both excellent tensile and impact properties, and maintains good interlaminar peel strength even at relatively low hot-pressing temperatures.

Description

Technical Field

[0001] This invention relates to the field of polypropylene materials, and more specifically, to a polypropylene sheet, a polypropylene fabric, a high-strength, high-impact polypropylene composite material, a method for preparing the same, and its applications. Background Technology

[0002] Polypropylene (PP) resin has low density, good heat resistance, and good rigidity, hardness, and weldability, which makes it widely used.

[0003] Self-reinforced polymer composites consist of a matrix and a reinforcing phase composed of different forms of the same polymer. The reinforcing phase is typically highly oriented fibers or ribbons. Most self-reinforced polymer composites are prepared using hot-pressing methods. When the reinforcing phase is hot-pressed under certain pressure and temperature, the surface of the reinforcing phase fibers melts to become the matrix melt. The matrix melt and the surface of the reinforcing phase co-crystallize during melting, thus providing sufficient interfacial bonding strength. For example, in US6312638B1, melt-spun oriented polyolefin fibers are hot-pressed, using specific temperature and pressure to partially melt and bond the polyolefin surface layer to prepare a polyolefin board. This preparation method is not only sensitive to the temperature of hot pressing, but also results in significant deorientation of the oriented fibers after hot pressing, leading to a significant decrease in mechanical strength.

[0004] To broaden the hot-pressing window and reduce the hot-pressing pressure, polyolefins with different melting points can be hot-pressed. For example, US8133537B2 describes the hot-pressing of three layers of polyolefin fibers with different melting points to obtain a polyolefin composite material, wherein the melting temperature of the first and second polyolefin layers is lower than that of the core layer. However, the impact strength and interlaminar peel strength of hot-pressed composite materials produced by this method are relatively low. Summary of the Invention

[0005] The purpose of this invention is to overcome the technical shortcomings of existing polypropylene composite materials, which are difficult to simultaneously possess a wide processing temperature range, strong mechanical properties, and high interlaminar peel strength. This invention provides polypropylene sheets, polypropylene fabrics, high-strength, high-impact polypropylene composite materials, their preparation methods, and applications. The polypropylene composite material obtained from the polypropylene sheets of this invention through hot pressing, etc., exhibits excellent mechanical properties and good interlaminar peel strength. Even at relatively low hot pressing temperatures and within a wide hot pressing temperature range, the interlaminar peel strength of the obtained polypropylene composite material remains high.

[0006] One objective of this invention is to provide a polypropylene sheet comprising a film layer A containing a polypropylene composition A and a film layer B containing a polypropylene composition B; the polypropylene sheet has a BAB layer structure, and the film layer B is located on both sides of the film layer A, and the film layers B on both sides of the film layer A may be the same or different.

[0007] The polypropylene composition A comprises homopolymer polypropylene a and impact copolymer polypropylene b; the polypropylene composition B comprises random copolymer polypropylene x and thermal bonding enhancer y.

[0008] According to the present invention, the thin film layers B on both sides of the thin film layer A may be the same or different. In a preferred embodiment of the present invention, the thin film layers B on both sides of the thin film layer A are the same.

[0009] The content range of each component in the polypropylene composition A is relatively wide. In a preferred embodiment of the present invention, based on the total weight of the polypropylene composition A, the polypropylene composition A includes 50-99 wt% homopolymer polypropylene a and 1-50 wt% impact copolymer polypropylene b; preferably, the polypropylene composition A includes 70-90 wt% homopolymer polypropylene a and 10-30 wt% impact copolymer polypropylene b.

[0010] The content range of each component in the polypropylene composition B is relatively wide. In a preferred embodiment of the present invention, based on the total weight of the polypropylene composition B, the polypropylene composition B includes 70-99 wt% random copolymer polypropylene x and 1-30 wt% thermal bonding reinforcing agent y; preferably, the polypropylene composition B includes 80-90 wt% random copolymer polypropylene x and 10-20 wt% thermal bonding reinforcing agent y.

[0011] The thickness percentage of the film layer A has a wide range of selection. In a preferred embodiment of the present invention, based on the total thickness of the polypropylene sheet, the thickness of the film layer A accounts for 51%-89% of the total thickness, preferably 71%-89%, and more preferably 71%-80%. The thicknesses of the film layers B on both sides of the film layer A can be the same or different, preferably the same.

[0012] The present invention does not limit the thickness of the polypropylene sheet, and it can be selected within a wide range according to its actual application field. Preferably, the thickness of the polypropylene sheet can be 10-1000μm, more preferably 30-500μm, and even more preferably 50-300μm.

[0013] According to the present invention, the thickness of film layers A and B can be controlled by the extruder melt pump during the processing.

[0014] The homopolymer polypropylene a has a wide range of material selection. In a preferred embodiment of the present invention, the melting point of the homopolymer polypropylene a is 160-170°C.

[0015] In a preferred embodiment of the present invention, the melt flow rate of the homopolymer polypropylene a at 190°C and 2.16 kg load is 0.5-50 g / 10 min, preferably 1-20 g / 10 min, and more preferably 2.5-18 g / 10 min.

[0016] In a preferred embodiment of the present invention, the isotacticity (mm) of the homopolymer polypropylene a is not less than 96%.

[0017] In a more preferred embodiment of the present invention, the homopolymer polypropylene a has a melting point of 160-170°C, a melt flow rate of 0.5-50 g / 10 min at 190°C and a load of 2.16 kg, preferably 1-20 g / 10 min, and more preferably 2.5-18 g / 10 min; the isotacticity (mm) of the homopolymer polypropylene is not less than 96%.

[0018] The impact-resistant copolymer polypropylene b has a wide range of material selection. In a preferred embodiment of the present invention, the melting point of the impact-resistant copolymer polypropylene b is 150-170°C.

[0019] In a preferred embodiment of the present invention, the monomer for copolymerizing the impact-resistant copolymer polypropylene b with propylene is ethylene or butene, preferably butene.

[0020] In a preferred embodiment of the present invention, the melt flow rate of the impact-resistant copolymer polypropylene b at 190°C and 2.16 kg load is 0.5-50 g / 10 min, preferably 1-20 g / 10 min, and more preferably 2.5-18 g / 10 min.

[0021] In a preferred embodiment of the present invention, the cantilever beam impact strength of the impact-resistant copolymer polypropylene b is not less than 20 KJ / m. 2 (Tested at 23℃).

[0022] In a more preferred embodiment of the present invention, the impact copolymer polypropylene b has a melting point of 150-170°C, and the monomer copolymerized with propylene is ethylene or butene, preferably butene; the melt flow rate of the impact copolymer polypropylene b at 190°C and 2.16 kg load is 0.5-50 g / 10 min, preferably 1-20 g / 10 min, and more preferably 2.5-18 g / 10 min.

[0023] According to the inventors' research, when the melt flow rate and polymer composition ratio of polypropylene composition A are within the above-mentioned preferred range, the impact-resistant copolymer polypropylene b in the composition can effectively absorb impact energy, meeting the impact performance requirements and giving the sheet good impact performance. Simultaneously, because the macromolecular chain segments in homopolymer polypropylene a are relatively regular, crystallization occurs during the sheet preparation process, thus the sheet also has good tensile properties.

[0024] The random copolymer polypropylene x has a wide range of material selection. In a preferred embodiment of the present invention, the melting point of the random copolymer polypropylene x is 120-140℃.

[0025] In a preferred embodiment of the present invention, the melt flow rate at 190°C and 2.16 kg load is 0.5-50 g / 10 min, preferably 1-20 g / 10 min, and more preferably 3-18 g / 10 min.

[0026] In a preferred embodiment of the present invention, the random polypropylene x is a copolymer of propylene and ethylene and / or butene, preferably an ethylene-propylene-butene terpolymer and / or a propylene-ethylene binary copolymer.

[0027] The selection range of the heat-bonding reinforcing agent y is relatively wide. In a preferred embodiment of the present invention, the melt flow rate of the heat-bonding reinforcing agent y at 190°C and 2.16kg load is 0.5-50g / 10min, preferably 1-20g / 10min, and more preferably 1-18g / 10min.

[0028] In a preferred embodiment of the present invention, the thermal bonding reinforcing agent y is selected from one or more of polyolefin elastomers, ethylene propylene diene monomer (EPDM) rubber, SEBS, SBS, EVA, and petroleum resins.

[0029] In a preferred embodiment of the present invention, the thermal bonding reinforcing agent y is a polyolefin elastomer and / or petroleum resin.

[0030] In a more preferred embodiment of the present invention, the thermal bonding reinforcing agent y is a polyolefin elastomer; preferably, the polyolefin elastomer is a copolymer elastomer of ethylene and propylene and / or α-olefin; even more preferably, the α-olefin is a C4-C12 α-olefin, more preferably 1-butene and / or 1-octene.

[0031] In another, more preferred embodiment of the present invention, the thermal bonding reinforcing agent y is a petroleum resin, wherein the petroleum resin is a C5 and / or C9 hydrogenated petroleum resin, preferably with a softening point of 100-150°C; more preferably, the petroleum resin is a cyclopentadiene type resin.

[0032] According to the inventors' research, when the melt flow rate and polymer composition ratio of polypropylene composition B are within the preferred range, the low melting point random copolymer polypropylene x and the heat-bonding reinforcing agent y in the composition can significantly reduce the hot-pressing temperature and widen the hot-pressing temperature window. Furthermore, the heat-bonding reinforcing agent y provides good adhesion performance for the sheet and can further improve the interlayer peel strength.

[0033] In a preferred embodiment of the present invention, the polypropylene composition A further contains a β-crystal nucleating agent, wherein the β-crystal nucleating agent is selected from at least one of polycyclic aromatic hydrocarbons, group IIA two-component complexes, aromatic diamides, rare earth compounds, and cyclic dicarboxylate nucleating agents.

[0034] The content range of the β-crystal nucleating agent is relatively wide. Preferably, based on 100 parts by weight of the total amount of the polypropylene composition A, the content of the β-crystal nucleating agent is 0.01-0.5 parts by weight. Specifically, for example, the content of the β-crystal nucleating agent can be 0.01, 0.05, 0.1, 0.2, 0.3, 0.4, or 0.5 parts by weight.

[0035] In a preferred embodiment of the present invention, the melting point of the polypropylene composition A is greater than that of the polypropylene composition B; preferably, the melting point of the homopolymer polypropylene a in the polypropylene composition A is greater than that of the random copolymer polypropylene x in the polypropylene composition B, and preferably the temperature difference between the corresponding melting points is greater than or equal to 10 degrees. In this preferred embodiment, the inventors of the present invention have surprisingly discovered that the polypropylene sheet obtained is hot-pressed to obtain a polypropylene composite material, which has superior mechanical properties and better interlaminar peel strength. Even at lower hot-pressing temperatures and over a wider range of hot-pressing temperatures, the polypropylene composite material obtained has higher interlaminar peel strength.

[0036] According to the inventors' research, when the melt flow rate, polymer composition ratio, and thickness distribution of film layer A of polypropylene composition A and polypropylene composition B are within the preferred range, the sheet preparation process can be made more stable, thereby giving the sheet better uniformity, tensile strength, impact performance, and interlayer peel strength.

[0037] The BAB layer structure of the polypropylene sheet can be prepared by various methods. In a preferred embodiment of the present invention, the BAB layer structure of the polypropylene sheet is obtained by co-extrusion of components including polypropylene composition A and polypropylene composition B.

[0038] The second objective of this invention is to provide a method for preparing polypropylene sheets, comprising co-extruding components including polypropylene composition A and polypropylene composition B; preferably, the method comprises co-extruding polypropylene composition A and polypropylene composition B according to a BAB structure, casting or calendering, stretching, and slitting to obtain polypropylene sheets.

[0039] In a preferred embodiment of the present invention, the preparation of the polypropylene composition A includes melt blending of components including the homopolymer polypropylene a and the impact copolymer polypropylene b. The melt blending conditions and equipment for the polypropylene composition A adopt the conditions and equipment for melt blending of polyolefins in the prior art. Preferably, the melt temperature is 150-170°C, and the equipment is preferably a twin-screw extruder.

[0040] In a preferred embodiment of the present invention, the preparation of the polypropylene composition B includes melt blending of components including the random copolymer polypropylene x and the thermal bonding reinforcing agent y. The melt blending conditions and equipment for the polypropylene composition B adopt the conditions and equipment for melt blending of polyolefins in the prior art. Preferably, the melt temperature is 110-150°C, and the equipment is preferably a twin-screw extruder.

[0041] The temperature range for co-extrusion molding and casting is relatively wide. In a preferred embodiment of the present invention, in step (1), the temperature for co-extrusion molding and casting is independently selected from 200-240°C; the temperature of the calendering roll is 50-70°C.

[0042] The range of stretching conditions is relatively wide. In a preferred embodiment of the present invention, the stretching conditions include: a stretching temperature of 90-165°C, preferably 90-140°C, more preferably 90-119°C, and a stretching ratio of 1-15 times; preferably 2-9 times.

[0043] According to some embodiments of the present invention, polypropylene composition A and polypropylene composition B are co-extruded according to a BAB structure and then cast or calendered to obtain a polypropylene co-extruded sheet. The extrusion calendering process may include passing the polypropylene co-extruded sheet sequentially through calendering rollers and traction rollers, followed by solid-state stretching, edge trimming, and winding to obtain the sheet. The extrusion casting temperature is 200-230°C, and the calendering roller temperature is 50-70°C. The specific process for preparing the film using the extrusion calendering method is a commonly used choice in the art and will not be elaborated further here.

[0044] A third objective of this invention is to provide a polypropylene fabric, a three-dimensional polypropylene fabric obtained by weaving the polypropylene sheets described above; preferably, the polypropylene fabric has a three-dimensional structure of plain weave, twill weave, and / or satin weave.

[0045] To facilitate weaving, it is preferable to cut the polypropylene sheet into polypropylene sheet cuts with a width of 2-5mm, and then weave them into polypropylene fabric.

[0046] In a more preferred embodiment of the present invention, the polypropylene fabric is a plain weave, twill weave, satin weave, or three-dimensional polypropylene fabric obtained by weaving a three-layer co-extruded polypropylene stretch flat strip, and the three-layer co-extruded polypropylene stretch flat strip includes at least one film layer A formed by a high-melting-point polypropylene composition A and at least one film layer B formed by a low-melting-point polypropylene composition B, wherein the polypropylene composition A includes homopolymer polypropylene a and impact copolymer polypropylene b; the polypropylene composition B includes random copolymer polypropylene x and a thermal bonding reinforcing agent y, and the polymer film layer B is located on both sides of layer A.

[0047] The fourth objective of this invention is to provide a polypropylene composite material, which is prepared by hot pressing multiple layers of polypropylene sheets and / or polypropylene fabrics as described above. Preferably, the polypropylene fabric is stacked from top to bottom with warp directions arranged at 0-90° intervals, preferably with more than or equal to 2 layers, more preferably with 2-200 layers, and most preferably with 4-100 layers. The multiple polypropylene sheets are stacked from top to bottom with their respective machine directions arranged at 0-90° intervals, preferably with more than or equal to 2 layers, more preferably with 2-200 layers, and most preferably with 4-100 layers.

[0048] In a preferred embodiment of the present invention, the polypropylene fabrics in each of the stacked layers may contain the same or different polypropylene composition A, and each layer of polypropylene fabric A may be independently selected, preferably the polypropylene composition A in each layer is the same.

[0049] In a preferred embodiment of the present invention, the polypropylene composite material has at least one of the following characteristics:

[0050] Longitudinal tensile strength ≥150 MPa, preferably ≥170 MPa;

[0051] Interlayer peel strength ≥1N / mm, preferably ≥1.2N / mm;

[0052] Tensile strength was determined according to the method specified in GB / T1040.1-2018, and interlaminar peel strength was determined according to the method specified in GB / T2358-98. The corresponding specimens for the above two tests were the standard specimens required in the above testing standards.

[0053] When the polypropylene composite material is obtained by hot pressing 24 layers of polypropylene fabric and the thickness is about 1.6 mm, the drop hammer impact strength is ≥228 J, preferably ≥240 J.

[0054] The drop hammer impact strength was determined according to the method specified in GB / T14153-1993, and the thickness of the sample was the same as the thickness of the prepared product.

[0055] The fifth objective of this invention is to provide a method for preparing the polypropylene composite material described above, the method comprising hot-pressing and fusing the polypropylene sheet and / or the polypropylene fabric into a laminate, and then cooling and shaping it to form the polypropylene composite material.

[0056] In a preferred embodiment of the present invention, the temperature of the hot-pressing fusion is 115-170°C, preferably 115-159°C, and more preferably 140-159°C.

[0057] In a preferred embodiment of the present invention, the pressure of the hot-press fusion is 2-10 MPa.

[0058] In a preferred embodiment of the present invention, the preheating time for hot pressing fusion is 5-600s, and the hot pressing time is 1-600s, preferably 10-500s.

[0059] In a preferred embodiment of the present invention, the cooling and shaping pressure is 2-8 MPa, and the cooling and shaping time is 30s-700s.

[0060] In a preferred embodiment of the present invention, the number of layers of the polypropylene sheet and / or polypropylene fabric stack is greater than or equal to 2 layers, preferably 2-200 layers; more preferably 4-100 layers.

[0061] In a preferred embodiment of the present invention, adjacent layers of the polypropylene sheet stack are placed at 0-90° along their respective machine directions, i.e., the stretching direction (MD).

[0062] In a preferred embodiment of the present invention, adjacent layers of the polypropylene fabric stack are placed at an angle of 0-90° between the warp and weft directions.

[0063] In a more preferred embodiment of the present invention, the method for preparing the high-strength, high-impact polypropylene composite material includes the following steps:

[0064] Step a: Polypropylene composition A and polypropylene composition B are co-extruded according to the BAB structure and then cast or calendered to obtain polypropylene co-extruded sheets; preferably, the extrusion casting or calendering temperature is 200-240℃ and the calendering roll temperature is 50-70℃.

[0065] Step b: The polypropylene co-extruded sheet is stretched at a certain temperature to obtain a polypropylene stretched sheet; preferably, the stretching temperature is 90-165℃, more preferably 90-140℃, and even more preferably 90-119℃, with a stretching ratio of 1-15 times, preferably 2-9 times.

[0066] Step c: Cut the polypropylene stretched sheet into polypropylene flat strips, and weave the flat strips into polypropylene fabrics; preferably, the width of the polypropylene flat strips is 2-5 mm, and the polypropylene fabrics include plain weave, twill weave, satin weave or other three-dimensional polypropylene fabrics.

[0067] Step d: The polypropylene fabrics are sequentially stacked and hot-pressed together, and then cooled and shaped to form a polypropylene composite material; preferably, in step d, the hot-pressing conditions are: hot-pressing temperature 115-170℃, preferably 115-159℃, more preferably 140-159℃; hot-pressing pressure 2-10 MPa, preheating time 5-600s, hot-pressing time 1-600s, preferably 10-500s, cooling pressure 2-8 MPa, cooling time 30s-700s; preferably, adjacent polypropylene fabrics in the polypropylene composite material can be placed at 0-90° between the warp and weft directions.

[0068] According to some embodiments of the present invention, in step c, a high-speed slitting machine with multiple blades can be used to cut the oriented polypropylene flat strip with a width of 2-5 mm; the oriented flat strip is then woven into plain weave, twill weave, satin weave and / or other three-dimensional polypropylene fabrics using a commercial weaving machine according to the designed fabric structure.

[0069] According to a preferred embodiment of the present invention, the pressure is preferably maintained continuously during the hot pressing and cooling process without any decrease. The hot pressing process is continuous, and preferably a continuous hot pressing composite material molding equipment is adopted, consisting of a preheating machine, a crawler-type continuous planar hot press, a crawler-type continuous planar cooling press, a sheet cutting machine, and a sheet stacking machine arranged in sequence. Preferably, the crawler-type continuous planar hot press has a preheating unit, an independent heating and pressurizing unit, an air cooling unit, and a lifting mechanism.

[0070] In the preparation process, the polypropylene sheets and / or polypropylene fabrics are sequentially stacked and preheated in a preheating machine. The preheated samples are then sequentially hot-pressed and fused using a tracked flatbed hot press, followed by cooling and shaping using a tracked continuous flatbed cooling press to produce a polypropylene composite material, i.e., a stacked hot-pressed product. Afterwards, the product is sliced ​​as needed using a sheet cutter, and then stacked and arranged using a sheet stacking machine. The hot-pressing temperature is controlled by the preheating unit, independent heating and pressurizing unit, and air-cooling unit in the tracked flatbed hot press, while the hot-pressing pressure is controlled by a lifting mechanism. According to the inventors' research, when the preparation process parameters are within the preferred range, and when the aforementioned preparation equipment is used to prepare the polymer composite material, the polymer composite material exhibits better tensile strength, impact performance, and interlaminar peel strength.

[0071] The sixth objective of this invention is to provide an application of the polypropylene sheet, polypropylene fabric, polypropylene composite material, and polypropylene composite material prepared by the preparation method described above in the fields of sports protection, automobile manufacturing, military materials, and consumer products.

[0072] According to specific embodiments of the present invention, the materials field includes the luggage and transportation industry, the footwear industry, the automobile manufacturing industry, the sports equipment manufacturing industry, the audio equipment manufacturing industry, and the military field.

[0073] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0074] (1) The polypropylene composite polymer of the present invention has good tensile strength, impact performance and interlaminar peel strength.

[0075] The polypropylene composite material has the following characteristics:

[0076] Longitudinal (MD) tensile strength ≥150 MPa, preferably ≥170 MPa; interlaminar peel strength ≥1 N / mm, preferably ≥1.2 N / mm; when the composite material is made of only 24 layers of polypropylene fabric hot-pressed together and the thickness is about 1.6 mm, the drop hammer impact strength ≥228 J, preferably ≥240 J.

[0077] (2) The polypropylene composite material of the present invention is suitable for preparation at a lower hot pressing temperature and a wider hot pressing temperature range, which effectively reduces the energy consumption of equipment and the damage to the composite material caused by high temperature operation. At the same time, it still has good interlayer peel strength when prepared at a lower hot pressing temperature.

[0078] (3) This preparation method can reduce the hot pressing operation time, while improving production efficiency and reducing production energy consumption.

[0079] (4) The present invention reduces the hot pressing temperature and expands the hot pressing temperature range to 50°C; effectively reducing equipment energy consumption and damage to composite materials under high temperature operation. Detailed Implementation

[0080] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0081] In the following embodiments and comparative examples:

[0082] The extrusion calender and solid phase stretching equipment were purchased from Tianjin Hengrui Company, and the model is HRPC-800 three-layer co-extrusion plastic stretching sheet production line.

[0083] The properties of the polypropylene composition and sheet were tested according to the following methods, and the film test results are shown in Table 1:

[0084] (1) Melt mass flow rate (MFR): The test shall be performed in accordance with the method specified in GB / T 3682-2000, wherein the test temperature is 190℃ and the load is 2.16kg;

[0085] (2) Melting point, determined according to the method specified in GB / T 28724-2012;

[0086] (3) Tensile strength: determined according to the method specified in GB / T1040.1-2018;

[0087] (4) Drop hammer impact strength: determined according to the method specified in GB / T14153-1993;

[0088] (5) Interlayer peel strength: The test shall be conducted in accordance with the method specified in QB / T2358-98.

[0089] In the following examples, the β-crystal nucleating agent with the brand name VP101B was sourced from the Beijing Research Institute of Chemical Industry, China Petroleum & Chemical Corporation; the sources of some raw materials are described in the examples, and the remaining raw materials are commercially available unless otherwise specified.

[0090] Example 1

[0091] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0092] (1) Preparation of polypropylene composition A:

[0093] Component a is a homopolymer polypropylene self-produced by the Beijing Research Institute of Chemical Industry, Sinopec, with a melting point of 160℃, a melt flow rate (melt mass flow rate) of 3.2 g / 10 min, and an isotacticity of 97%; component b is a polypropylene impact copolymer self-produced by the Beijing Research Institute of Chemical Industry, Sinopec (with a cantilever beam impact strength of 23 KJ / m under 23℃ testing conditions). 2 The ethylene content is 11% wt, the melt flow rate is 2.0 g / 10 min, and the melting point is 155℃.

[0094] The components obtained above were weighed and mixed according to the specified proportions, with component a (Wa) comprising 80 parts by weight and component b (Wb) comprising 20 parts by weight. 0.05 parts by weight of β-crystal nucleating agent (VP101B) were added. The mixture was then added to a high-speed mixer and mixed thoroughly. The mixed material was then fed into the feeder of a twin-screw extruder manufactured by W&P. The material entered the twin screws via the feeder. During processing, the screw temperature was maintained between 200-230°C. After melting and mixing evenly in the screws, extrusion, granulation, and drying, polypropylene composition granules were obtained. The melt flow rate was measured to be 4.6 g / 10 min; the melting point of polypropylene composition A was 157°C.

[0095] (2) Preparation of polypropylene composition B:

[0096] Component x is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry of Sinopec. It is an ethylene-propylene-butene terpolymer with a melting point of 140℃ and a melt flow rate of 6.6 g / 10 min. Component y is a polyolefin elastomer of grade 6102 purchased from Exxon. It is an ethylene-propylene copolymer with an ethylene content of 16% wt and a melt flow rate of 1.4 g / 10 min at 190℃ and a load of 2.16 kg.

[0097] The components prepared above are weighed and mixed according to the ratio, wherein the mass part of component x, Wx, is 85 parts by weight and the mass part of component y, Wy, is 15 parts by weight. Other steps are the same as in step (1). Finally, polypropylene composition B granules are obtained. The melt mass flow rate is tested to be 5.2 g / 10 min and the melting point is 138 °C.

[0098] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0099] The polypropylene composition A and polypropylene composition B granules obtained in steps (1) and (2) above are dried. Then, polypropylene composition A is added to the core extruder of a multilayer extrusion calender, and polypropylene composition B is added to the upper and lower surface extruders of a multilayer extrusion casting machine.

[0100] After the granules are co-extruded and compounded through the die of an extruder, they pass through calendering rollers and traction rollers in sequence, and then undergo solid-phase stretching, edge trimming and winding to obtain the sheet material.

[0101] The extrusion casting temperature is 230℃, and the calendering roll temperature is 55℃. The solid-phase stretching process is carried out at a temperature of 135℃, a stretching rate of 2 m / min, and a stretching ratio of 7 times. After stretching, the film is wound up to form a polypropylene sheet (composite film), which consists of an upper surface layer (film layer B), a core layer (film layer A), and a lower surface layer (film layer B).

[0102] The thickness of the polypropylene sheet (composite film) mentioned above is 80 μm, wherein the thickness of film layer A accounts for 80% of the total thickness of the sheet.

[0103] (4) Preparation of polypropylene fabric:

[0104] The three-layer co-extruded polypropylene sheet obtained in step (3) above is cut into a high-speed slitting machine with multiple blades to obtain an oriented polypropylene flat strip with a width of 3mm; the oriented flat strip is woven into a plain weave polypropylene fabric according to the designed fabric structure using a commercial weaving machine.

[0105] (5) Preparation of polypropylene composite materials:

[0106] The polypropylene fabrics obtained in step (4) were sequentially stacked and hot-pressed to form a laminated polypropylene sheet. The laminated polypropylene sheet consisted of 24 layers of polypropylene fabric, with the warp and weft directions arranged at 90° angles. The hot-pressing conditions were: temperature 150℃, hot-pressing pressure 5 MPa, preheating time 180 s, hot-pressing time 180 s, and cooling time 600 s. The thickness of the prepared polypropylene composite material was 1.67 mm.

[0107] Example 2

[0108] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0109] (1) Preparation of polypropylene composition A:

[0110] Component a is a homopolymer polypropylene self-produced by the Beijing Research Institute of Chemical Industry of Sinopec, with a melting point of 165℃, a melt flow rate of 8.1 g / 10 min, and an isotacticity of 97%; component b is a polypropylene impact copolymer self-produced by the Beijing Research Institute of Chemical Industry of Sinopec, with a cantilever beam impact strength of 25 KJ / m under a test condition of 23℃. 2 The ethylene content is 8% wt, the melt flow rate is 3.2 g / 10 min, and the melting point is 155℃.

[0111] The components obtained above were weighed and mixed according to the specified proportions, with component a (Wa) comprising 70 parts by weight and component b (Wb) comprising 30 parts by weight. 0.05 parts by weight of β-crystal nucleating agent (VP101B) were added. The mixture was then added to a high-speed mixer and mixed thoroughly. The mixed material was then fed into the feeder of a twin-screw extruder manufactured by W&P. The material entered the twin screws via the feeder. During processing, the screw temperature was maintained between 200-230°C. After melting and mixing evenly in the screws, extrusion, granulation, and drying, polypropylene composition granules were obtained. The melt flow rate was measured to be 7.3 g / 10 min, and the melting point of polypropylene composition A was 161°C.

[0112] (2) Preparation of polypropylene composition B:

[0113] Component x is a random copolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, with a melting point of 134℃. It is an ethylene-propylene-butene terpolymer with a melt flow rate of 5.2 g / 10 min. Component y is a polyolefin elastomer produced by Sinopec Beijing Research Institute of Chemical Industry, which is an ethylene-propylene copolymer with an ethylene content of 15% wt. It has a melting point of 105℃ and a melt flow rate of 9 g / 10 min at 190℃ and a load of 2.16 kg.

[0114] The components obtained above were weighed and mixed according to the specified proportions, wherein the mass fraction of component x, Wx, was 80 parts by weight and the mass fraction of component y, Wy, was 20 parts by weight. Other steps were the same as in step (1), and polypropylene composition B granules were finally obtained. The melt flow rate was measured to be 9.6 g / 10 min. The melting point of polypropylene composition B is 130 °C.

[0115] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0116] The preparation process is the same as step (3) in Example 1.

[0117] (4) Preparation of polypropylene fabric:

[0118] The preparation process is the same as step (4) in Example 1.

[0119] (5) Preparation of polypropylene composite materials:

[0120] The preparation process is the same as step (5) in Example 1.

[0121] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0122] Example 3

[0123] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0124] (1) Preparation of polypropylene composition A:

[0125] Same as in Example 1, wherein component a (Wa) has 90 parts by weight and component b (Wb) has 10 parts by weight. 0.05 parts by weight of β-crystal nucleating agent (VP101B) were added. Polypropylene composition A granules were obtained, with a melt flow rate of 6.8 g / 10 min and a melting point of 158°C.

[0126] (2) Preparation of polypropylene composition B:

[0127] Same as in Example 1, wherein the mass fraction of component x, Wx, is 90 parts by weight and the mass fraction of component y, Wy, is 10 parts by weight, and finally polypropylene composition B granules are obtained. The melt flow rate is tested to be 8.7 g / 10 min and the melting point of polypropylene composition B is 139 °C.

[0128] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0129] The preparation process is the same as step (3) in Example 1.

[0130] (4) Preparation of polypropylene fabric:

[0131] The preparation process is the same as step (4) in Example 1.

[0132] (5) Preparation of polypropylene composite materials:

[0133] The preparation process is the same as step (5) in Example 1.

[0134] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0135] Example 4

[0136] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0137] (1) Preparation of polypropylene composition A:

[0138] The preparation process is the same as step (1) in Example 1.

[0139] (2) Preparation of polypropylene composition B:

[0140] The preparation process is the same as step (2) of Example 1.

[0141] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0142] The main steps are the same as in Example 1. The thickness of the polypropylene sheet is 80 μm, wherein the thickness of the film layer A accounts for 90% of the total thickness of the sheet.

[0143] (4) Preparation of polypropylene fabric:

[0144] The preparation process is the same as step (4) in Example 1.

[0145] (5) Preparation of polypropylene composite materials:

[0146] The preparation process is the same as step (5) in Example 1.

[0147] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0148] Example 5

[0149] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0150] (1) Preparation of polypropylene composition A:

[0151] The preparation process is the same as step (1) in Example 1.

[0152] (2) Preparation of polypropylene composition B:

[0153] The preparation process is the same as step (2) of Example 1.

[0154] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0155] The main steps are the same as in Example 1. The thickness of the polypropylene sheet is 80 μm, wherein the thickness of the film layer A accounts for 70% of the total thickness of the sheet.

[0156] (4) Preparation of polypropylene fabric:

[0157] The preparation process is the same as step (4) in Example 1.

[0158] (5) Preparation of polypropylene composite materials:

[0159] The preparation process is the same as step (5) in Example 1.

[0160] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0161] Example 6

[0162] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0163] (1) Preparation of polypropylene composition A:

[0164] The preparation process is the same as step (1) in Example 1.

[0165] (2) Preparation of polypropylene composition B:

[0166] The preparation process is the same as step (2) of Example 1.

[0167] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0168] The preparation process is the same as step (3) in Example 1.

[0169] (4) Preparation of polypropylene fabric:

[0170] The main steps are the same as step (4) in Example 1. The oriented flat strip is woven into a satin polypropylene fabric by using a commercial weaving machine according to the designed fabric structure.

[0171] (5) Preparation of polypropylene composite materials:

[0172] The preparation process is the same as step (5) in Example 1.

[0173] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0174] Example 7

[0175] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0176] (1) Preparation of polypropylene composition A:

[0177] The preparation process is the same as step (1) in Example 1.

[0178] (2) Preparation of polypropylene composition B:

[0179] The preparation process is the same as step (2) of Example 1.

[0180] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0181] The main preparation process is the same as step (3) in Example 1. The sheet stretching ratio is 10 times.

[0182] (4) Preparation of polypropylene fabric:

[0183] The preparation process is the same as step (4) in Example 1.

[0184] (5) Preparation of polypropylene composite materials:

[0185] The preparation process is the same as step (5) in Example 1.

[0186] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0187] Example 8

[0188] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0189] (1) Preparation of polypropylene composition A:

[0190] The preparation process is the same as step (1) in Example 1.

[0191] (2) Preparation of polypropylene composition B:

[0192] The preparation process is the same as step (2) of Example 1.

[0193] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0194] The preparation process is the same as step (3) in Example 1.

[0195] (4) Preparation of polypropylene fabric:

[0196] The preparation process is the same as step (4) in Example 1.

[0197] (5) Preparation of polypropylene composite materials:

[0198] The main preparation process is the same as step (5) in Example 1. The polypropylene fabric is placed at a 45° angle between the warp and weft directions.

[0199] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0200] Example 9

[0201] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0202] (1) Preparation of polypropylene composition A:

[0203] The preparation process is the same as step (1) in Example 1.

[0204] (2) Preparation of polypropylene composition B:

[0205] The preparation process is the same as step (2) of Example 1.

[0206] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0207] The preparation process is the same as step (3) in Example 1.

[0208] (4) Preparation of polypropylene fabric:

[0209] The preparation process is the same as step (4) in Example 1.

[0210] (5) Preparation of polypropylene composite materials:

[0211] The main preparation process is the same as step (5) in Example 1. The polypropylene fabric is placed with the warp direction at 0° to the warp direction.

[0212] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0213] Example 10

[0214] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0215] (1) Preparation of polypropylene composition A:

[0216] The preparation process is the same as step (1) in Example 1.

[0217] (2) Preparation of polypropylene composition B:

[0218] The preparation process is the same as step (2) of Example 1.

[0219] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0220] The preparation process is the same as step (3) in Example 1.

[0221] (4) Preparation of polypropylene fabric:

[0222] The preparation process is the same as step (4) in Example 1.

[0223] (5) Preparation of polypropylene composite materials:

[0224] The main steps are the same as in Example 1. The laminated polypropylene sheet includes two layers of polypropylene fabric. The hot-pressing conditions used are: temperature 140℃, hot-pressing pressure 2 MPa, preheating time 120 s, hot-pressing time 10 s, and cooling time 300 s. The thickness of the prepared polypropylene composite material is 128 μm.

[0225] Example 11

[0226] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0227] (1) Preparation of polypropylene composition A:

[0228] The preparation process is the same as step (1) in Example 1.

[0229] (2) Preparation of polypropylene composition B:

[0230] The preparation process is the same as step (2) of Example 1.

[0231] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0232] The preparation process is the same as step (3) in Example 1.

[0233] (4) Preparation of polypropylene fabric:

[0234] The preparation process is the same as step (4) in Example 1.

[0235] (5) Preparation of polypropylene composite materials:

[0236] The main steps are the same as in Example 1. The laminated polypropylene sheet includes 100 layers of polypropylene fabric. The hot-pressing conditions used are: 159°C, hot-pressing pressure of 10 MPa, preheating time of 300 s, hot-pressing time of 300 s, and cooling time of 700 s. The thickness of the prepared polypropylene composite material is 7.23 mm.

[0237] Example 12

[0238] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0239] (1) Preparation of polypropylene composition A:

[0240] The preparation process is the same as step (1) in Example 1.

[0241] (2) Preparation of polypropylene composition B:

[0242] The preparation process is the same as step (2) of Example 1.

[0243] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0244] The preparation process is the same as step (3) in Example 1.

[0245] (4) Preparation of polypropylene fabric:

[0246] The preparation process is the same as step (4) in Example 1.

[0247] (5) Preparation of polypropylene composite materials:

[0248] The main steps are the same as in Example 1. The temperature is 155℃, the hot-pressing pressure is 8 MPa, the preheating time is 300s, the hot-pressing time is 300s, and the cooling time is 700s. The thickness of the prepared polypropylene composite material is 1.58mm.

[0249] Example 13

[0250] This embodiment illustrates the preparation of the polypropylene composition, three-layer co-extruded polypropylene sheet, polypropylene fabric, and polypropylene composite material provided by the present invention.

[0251] (1) Preparation of polypropylene composition A:

[0252] The preparation process is the same as step (1) in Example 1.

[0253] (2) Preparation of polypropylene composition B:

[0254] The preparation process is the same as step (2) of Example 1.

[0255] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0256] The preparation process is the same as step (3) in Example 1.

[0257] (4) Preparation of polypropylene composite materials:

[0258] Instead of preparing polypropylene fabric, the three-layer co-extruded polypropylene sheet obtained in step (3) was used to replace the polypropylene fabric obtained in step (4) of Example 1, and the sheets were sequentially stacked and hot-pressed according to step (5) of Example 1. The thickness of the prepared polypropylene composite material was 1.51 mm.

[0259] Comparative Example 1

[0260] Three-layer co-extruded polypropylene sheets were prepared according to the method of Example 1. However, only polypropylene composition A was used for extrusion casting into a single-layer film with a thickness of 80 μm. Polypropylene fabrics and polypropylene composites were also prepared according to the method of Example 1.

[0261] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0262] Comparative Example 2

[0263] Three-layer co-extruded polypropylene sheets were prepared according to the method of Example 1. However, only polypropylene composition B was used for extrusion casting into a single-layer film with a thickness of 80 μm. Polypropylene fabrics and polypropylene composites were also prepared according to the method of Example 1.

[0264] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0265] Comparative Example 3

[0266] Three-layer co-extruded polypropylene sheets were prepared according to the method of Example 1. However, polypropylene composition A contained only component b. Polypropylene fabrics and polypropylene composites were also prepared according to the method of Example 1.

[0267] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0268] Comparative Example 4

[0269] Three-layer co-extruded polypropylene sheets were prepared according to the method of Example 1. However, polypropylene composition B contained only component y. Polypropylene fabrics and polypropylene composites were also prepared according to the method of Example 1.

[0270] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0271] Comparative Example 5

[0272] Three-layer co-extruded polypropylene sheets were prepared according to the method of Example 1. The thickness of film layer A accounted for 95% of the total sheet thickness. Polypropylene fabrics and polypropylene composites were also prepared according to the method of Example 1.

[0273] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0274] Comparative Example 6

[0275] Three-layer co-extruded polypropylene sheets were prepared according to the method of Example 1. The thickness of film layer A was 50% of the total sheet thickness. Polypropylene fabrics and polypropylene composites were also prepared according to the method of Example 1.

[0276] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0277] Experimental Example

[0278] The polypropylene composite materials obtained in the above examples and comparative examples were tested according to the following methods, and the test results are shown in Table 1.

[0279] (1) Tensile strength: Samples were prepared and tested according to the methods specified in GB / T1040.1-2018;

[0280] (2) Interlayer peel strength: Samples were prepared and measured in accordance with the method specified in QB / T2358-98.

[0281] (3) Drop hammer impact strength: The test was conducted according to the method specified in GB / T14153-1993. Among them, the thickness of the polypropylene composite materials obtained in Examples 1-9 and Comparative Examples 1-6 were all similar, around 1.6 mm, and all within the range of 1.6 mm ± 1 mm.

[0282] Table 1

[0283] serial number Tensile strength (MPa) Drop hammer impact strength (J) Peel strength (N / mm) Example 1 187 246.81 1.23 Example 2 176 242.16 1.34 Example 3 194 240.83 1.21 Example 4 201 249.14 1.07 Example 5 164 257.68 1.45 Example 6 171 273.98 1.12 Example 7 257 228.96 1.14 Example 8 176 243.71 1.24 Example 9 154 228.96 1.22 Example 10 205 20.76 1.28 Example 11 158 999.31 1.21 Example 12 171 244.49 1.36 Example 13 195 241.38 1.38 Comparative Example 1 198 153.68 0.56 Comparative Example 2 89 241.38 2.47 Comparative Example 3 136 222.75 1.28 Comparative Example 4 178 231.29 0.87 Comparative Example 5 179 202.57 0.63 Comparative Example 6 104 227.41 1.98

[0284] The results from the examples in Table 1 show that the polypropylene composite material prepared according to the present invention has both excellent tensile and impact resistance, as well as good interlaminar peel strength at relatively low hot-pressing temperatures. The longitudinal (MD) tensile strength of the polypropylene composite sheet of the present invention is ≥150 MPa, and the interlaminar peel strength is ≥1 N / mm. When the polypropylene composite material is made of 24 layers of polypropylene fabric hot-pressed together with a thickness of approximately 1.6 mm, the drop hammer impact strength is ≥228 J.

[0285] As can be seen from the preferred embodiments 1-3, the longitudinal (MD) tensile strength of the polypropylene composite material prepared by the present invention is ≥170 MPa, the interlaminar peel strength is ≥1.2 N / mm, and the drop hammer impact strength is ≥240 J when the polypropylene composite material is made of 24 layers of polypropylene fabric hot-pressed together and the thickness is about 1.6 mm.

[0286] As can be seen from Comparative Examples 1-6, using only a single-layer sheet structure or using interlayer ratios outside the scope of the examples will lead to a decrease in the performance of the laminated polypropylene sheets or fabrics, resulting in a significant decrease in the tensile strength, impact properties, or interlayer peel strength of the obtained polypropylene composite material.

[0287] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

[0288] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A polypropylene composite material, wherein the polypropylene composite material is prepared by hot pressing polypropylene sheets and / or polypropylene fabrics; wherein the number of layers of the polypropylene sheets and / or the polypropylene fabrics is greater than or equal to 2; The polypropylene fabric is a three-dimensional polypropylene fabric woven from the polypropylene sheet; The polypropylene sheet includes a film layer A containing a polypropylene composition A and a film layer B formed from a polypropylene composition B; the polypropylene sheet has a BAB layer structure, and the film layer B is located on both sides of the film layer A, and the film layers B on both sides of the film layer A may be the same or different. in, Polypropylene composition A comprises homopolymer polypropylene a and impact copolymer polypropylene b, and the preparation of polypropylene composition A includes melt blending the components including homopolymer polypropylene a and impact copolymer polypropylene b; polypropylene composition B consists of random copolymer polypropylene x and thermal bonding enhancer y. Based on the total thickness of the polypropylene sheet, the thickness of the film layer A accounts for 51%-89% of the total thickness; Based on the total weight of the polypropylene composition A, the polypropylene composition A comprises 50-99 wt% homopolymer polypropylene a and 1-50 wt% impact copolymer polypropylene b. Based on the total weight of the polypropylene composition B, the polypropylene composition B comprises 70-99 wt% random copolymer polypropylene x and 1-30 wt% thermal bonding enhancer y. The heat-bonding reinforcing agent y is selected from one or more of polyolefin elastomers, ethylene propylene diene monomer (EPDM) rubber, SEBS, SBS, EVA, and petroleum resins.

2. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composition A comprises 70-90 wt% homopolymer polypropylene a and 10-30 wt% impact copolymer polypropylene b.

3. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composition B comprises 80-90 wt% random copolymer polypropylene x and 10-20 wt% thermal bonding enhancer y.

4. The polypropylene composite material according to claim 1, characterized in that: Based on the total thickness of the polypropylene sheet, the thickness of the film layer A accounts for 71%-89% of the total thickness.

5. The polypropylene composite material according to claim 1, characterized in that: Based on the total thickness of the polypropylene sheet, the thickness of the film layer A accounts for 71%-80% of the total thickness.

6. The polypropylene composite material according to claim 1, characterized in that: The homopolymer polypropylene a has a melting point of 160-170℃; and / or, The homopolymer polypropylene a has a melt flow rate of 0.5-50 g / 10 min at 190 °C and a load of 2.16 kg; and / or, The isotacticity of the homopolymer polypropylene a is not less than 96%.

7. The polypropylene composite material according to claim 6, characterized in that: The homopolymer polypropylene a has a melt flow rate of 1-20 g / 10 min at 190 °C and 2.16 kg load.

8. The polypropylene composite material according to claim 6, characterized in that: The homopolymer polypropylene a has a melt flow rate of 2.5-18 g / 10 min at 190 °C and 2.16 kg load.

9. The polypropylene composite material according to claim 1, characterized in that: The impact-resistant copolymer polypropylene b has a melting point of 150-170℃; and / or, The monomer copolymerized with propylene in the impact-resistant copolymer polypropylene b is ethylene or butene; and / or, The impact-resistant copolymer polypropylene b has a melt flow rate of 0.5-50 g / 10 min at 190°C and a load of 2.16 kg; and / or, The cantilever beam impact strength of the impact-resistant copolymer polypropylene b is not less than 20 KJ / m. 2 .

10. The polypropylene composite material according to claim 9, characterized in that: The monomer for the copolymerization of the impact-resistant polypropylene b and propylene is butene; and / or, The impact-resistant copolymer polypropylene b has a melt flow rate of 1-20 g / 10 min at 190°C and 2.16 kg load.

11. The polypropylene composite material according to claim 9, characterized in that: The impact-resistant copolymer polypropylene b has a melt flow rate of 2.5-18 g / 10 min at 190°C and 2.16 kg load.

12. The polypropylene composite material according to claim 1, characterized in that: The random copolymer polypropylene x has a melting point of 120-140℃; and / or, The random copolymer polypropylene x has a melt flow rate of 0.5-50 g / 10 min at 190 °C and 2.16 kg load; and / or, The random copolymer polypropylene x is a copolymer of propylene with ethylene and / or butene.

13. The polypropylene composite material according to claim 12, characterized in that: The random copolymer polypropylene x has a melt flow rate of 1-20 g / 10 min at 190 °C and 2.16 kg load; and / or, The random copolymer polypropylene x is an ethylene-propylene-butene terpolymer and / or a propylene-ethylene binary copolymer.

14. The polypropylene composite material according to claim 12, characterized in that: The random copolymer polypropylene x has a melt flow rate of 3-18 g / 10 min at 190 °C and 2.16 kg load.

15. The polypropylene composite material according to claim 1, characterized in that: The melt flow rate of the heat-bonding reinforcing agent y at 190℃ and 2.16kg load is 0.5-50g / 10min.

16. The polypropylene composite material according to claim 15, characterized in that: The melt flow rate of the heat-bonding reinforcing agent y at 190°C and 2.16 kg load is 1-20 g / 10 min.

17. The polypropylene composite material according to claim 15, characterized in that: The melt flow rate of the heat-bonding reinforcing agent y at 190°C and 2.16 kg load is 1-18 g / 10 min.

18. The polypropylene composite material according to claim 1, characterized in that: The heat-adhesive reinforcing agent y is a polyolefin elastomer and / or petroleum resin.

19. The polypropylene composite material according to claim 18, characterized in that: The heat-adhesive reinforcing agent y is a polyolefin elastomer and / or petroleum resin; The polyolefin elastomer is a copolymer elastomer of ethylene with propylene and / or α-olefin; The petroleum resin is a hydrogenated petroleum resin of C5 and / or C9.

20. The polypropylene composite material according to claim 19, characterized in that: The polyolefin elastomer is a copolymer elastomer of ethylene and propylene and / or α-olefin; the α-olefin is a C4-C12 α-olefin; and / or, The petroleum resin is a C5 and / or C9 hydrogenated petroleum resin with a softening point of 100-150℃.

21. The polypropylene composite material according to claim 19, characterized in that: The polyolefin elastomer is a copolymer elastomer of ethylene with propylene and / or α-olefins; the α-olefin is 1-butene and / or 1-octene; and / or, The petroleum resin is a C5 and / or C9 hydrogenated petroleum resin, and the petroleum resin is a cyclopentadiene type resin.

22. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composition A also contains a β-crystal nucleating agent.

23. The polypropylene composite material according to claim 22, characterized in that: The β-crystal nucleating agent is selected from at least one of polycyclic aromatic hydrocarbons, group IIA binary complexes, aromatic diamides, rare earth compounds, and cyclic dicarboxylate nucleating agents; and / or, Based on a total amount of 100 parts by weight of the polypropylene composition A, the content of the β-crystal nucleating agent is 0.01-0.5 parts by weight.

24. The polypropylene composite material according to claim 1, characterized in that: The melting point of polypropylene composition A is greater than that of polypropylene composition B; and / or, The BAB layer structure of the polypropylene sheet is obtained by co-extrusion of components including polypropylene composition A and polypropylene composition B.

25. The polypropylene composite material according to claim 1, characterized in that: The melting point of the polypropylene composition A is greater than that of the polypropylene composition B; The melting point of homopolymer polypropylene a in polypropylene composition A is greater than the melting point of random copolymer polypropylene x in polypropylene composition B.

26. The polypropylene composite material according to claim 1, characterized in that: The melting point of the polypropylene composition A is greater than that of the polypropylene composition B; The melting point of homopolymer polypropylene a in polypropylene composition A is greater than the melting point of random copolymer polypropylene x in polypropylene composition B, and the temperature difference between the corresponding melting points is greater than or equal to 10°C.

27. The polypropylene composite material according to claim 1, characterized in that: The method for preparing the polypropylene sheet includes co-extruding components comprising polypropylene composition A and polypropylene composition B.

28. The polypropylene composite material according to claim 27, characterized in that, The method for preparing the polypropylene sheet includes co-extruding, casting or calendering, and stretching polypropylene composition A and polypropylene composition B according to a BAB structure to obtain a polypropylene sheet.

29. The polypropylene composite material according to claim 28, characterized in that, The preparation of the polypropylene composition B includes melt blending of components including the random copolymer polypropylene x and the thermal bonding reinforcing agent y; and / or, The temperatures for co-extrusion and casting are each independently selected from 200-240°C; and / or, The temperature of the calender rolls is 50-70℃; and / or, The stretching conditions include: a stretching temperature of 90-165℃; and a stretching ratio of 1-15 times.

30. The polypropylene composite material according to claim 28, characterized in that, The stretching conditions include: a stretching temperature of 90-140℃ and a stretching ratio of 2-9 times.

31. The polypropylene composite material according to claim 28, characterized in that, The stretching conditions include: a stretching temperature of 90-119℃ and a stretching ratio of 2-9 times.

32. The polypropylene composite material according to claim 1, characterized in that, The polypropylene fabric has a three-dimensional structure of plain weave, twill weave, and / or satin weave.

33. The polypropylene composite material according to any one of claims 1-32, characterized in that, The multi-layer polypropylene sheets are stacked from top to bottom at 0-90° angles along their respective machine directions.

34. The polypropylene composite material according to any one of claims 1-32, characterized in that, The multi-layered polypropylene fabric consists of warp threads stacked at 0-90° intervals from top to bottom.

35. The polypropylene composite material according to any one of claims 1-32, characterized in that, The polypropylene sheet and / or polypropylene fabric has 2-200 layers.

36. The polypropylene composite material according to any one of claims 1-32, characterized in that, The polypropylene sheet and / or polypropylene fabric has 4-100 layers.

37. A method for preparing a polypropylene composite material according to any one of claims 1-36, the method comprising hot-pressing and fusing the polypropylene sheet and / or the polypropylene fabric together, and then cooling and shaping it to form a polypropylene composite material.

38. The preparation method according to claim 37, characterized in that: The hot-pressing fusion temperature is 115-170℃; and / or, The pressure for the hot-pressing fusion is 2-10 MPa; and / or, The preheating time for the hot-pressing fusion is 5-600s, and the hot-pressing time is 1-600s; and / or, The cooling and setting pressure is 2-8 MPa, and the cooling and setting time is 30-700 seconds; and / or, The adjacent layers of the polypropylene fabric stack are placed at an angle of 0-90° between the warp directions; and / or, The adjacent layers of the polypropylene sheet stack are placed at 0-90° along their respective machine directions.

39. The preparation method according to claim 37, characterized in that: The hot-pressing fusion temperature is 115-159℃; and / or, The preheating time for the hot-pressing fusion is 5-600s, and the hot-pressing time is 10-500s; and / or, The number of layers in the polypropylene sheet and / or the polypropylene fabric stack is 2-200.

40. The preparation method according to claim 37, characterized in that: The hot-pressing fusion temperature is 140-159℃; and / or, The number of layers in the polypropylene sheet and / or the polypropylene fabric stack is 4-100.

41. The application of the polypropylene composite material according to any one of claims 1-36 and the polypropylene composite material prepared by the preparation method according to any one of claims 37-40 in the fields of military materials and consumer products.

42. The application according to claim 41, characterized in that: Its applications include sports protection and automobile manufacturing.