Polypropylene composite material with melting point gradient structure, and preparation method and system thereof and application

Abstract

This invention relates to a polypropylene composite material, disclosing a gradient-structured polypropylene composite material, its preparation method and system, and its applications. The composite material comprises multiple sequentially stacked polypropylene sheet units; each polypropylene sheet unit includes a core layer A. i and the outer B on both sides i B' i The structure is B i A i B' i The structure of this composite material is...B i A i B' i ...B1A1B'1, B i A i B' i ...the polypropylene composition A i The melting point is greater than that of the polypropylene composition B. i B' i The melting point of the polypropylene composition B; i B' i The melting point of each is greater than that of the adjacent polypropylene composition B'. i‑1 B i‑1 The melting point of the polypropylene composite material of the present invention has both excellent tensile and impact properties, as well as good interlaminar peel strength at relatively low hot-pressing temperatures.

Description

Technical Field

[0001] This invention relates to a polypropylene composite material, and more specifically, to a polypropylene composite material with a melting point gradient structure, its preparation method and system, and its applications. Background Technology

[0002] In recent years, high-strength and high-impact polymer composites, especially self-reinforced polymer composites, which are easy to recycle and lightweight, have become one of the hot topics of research.

[0003] In self-reinforced polymer composites, the reinforcing phase and matrix are composed of the same polymer but in different forms. The reinforcing phase is typically highly oriented fibers or ribbons. Most self-reinforced polymer composites are prepared using a hot-pressing method. 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 bond strength.

[0004] For example, in US8021592B2, melt-spun oriented polyolefin fibers with a weight-average molecular weight of less than 250,000 are woven and then hot-pressed. This method utilizes specific high temperatures, pressures, and cooling times to partially melt and bond the surface layer of the polyolefin fabric to prepare a polyolefin board. This preparation method is sensitive to the temperature of the hot pressing process, requiring high temperatures. After hot pressing, the oriented fibers in the resulting composite polyolefin fibers undergo significant decomposition and orientation, resulting in a marked decrease in mechanical strength. The self-reinforcing effect needs further improvement.

[0005] To broaden the hot-pressing window and reduce the hot-pressing pressure, US8133537B2 describes the hot-pressing of three layers of polyolefin fibers with different melting points to obtain a polyolefin composite material. The melting temperatures of the first and second polyolefin layers are lower than those of the core layer, and it is emphasized that the viscosity of the second polymer is no more than approximately 10% of the viscosity of the first polymer measured at 170°C. However, hot-pressed composite materials produced by this method have relatively low impact strength and interlaminar peel strength, and cannot achieve both good mechanical properties and high interlaminar peel strength. Summary of the Invention

[0006] The purpose of this invention is to overcome the technical problem that existing polypropylene composite materials often fail to simultaneously possess a wide processing temperature range, strong mechanical properties, and high interlaminar peel strength. This invention provides a polypropylene composite material with a melting point gradient structure, its preparation method and system, and its applications through the design of a melting point gradient structure in laminated polypropylene. This preparation method can reduce hot-pressing operation time, while improving production efficiency and reducing energy consumption. The polypropylene composite material obtained by this method exhibits excellent mechanical properties and good interlaminar peel strength.

[0007] One objective of this invention is to provide a polypropylene composite material comprising a plurality of sequentially stacked polypropylene sheet units; each polypropylene sheet unit includes a core layer A. i and located in core layer A i Outer B on both sides i B' i The structure is B i A i B' i The structure of the polypropylene composite material, from bottom to top, is B. n A n B' n ...B i A i B' i ...B2A2B'2, B1A1B'1, B2A2B'2...B i A i B' i ...B n A n B' n The total number of layers in the polypropylene sheet unit is 2n-1; i and n are both integers not less than 2, and i ≤ n; where, the core layer A in the polypropylene sheet unit i Composition A containing polypropylene i Outer layer B i With outer layer B' i Whether the composition is the same or different, each composition corresponds to a polypropylene composition B. i Polypropylene composition B' i The polypropylene composition A i The melting point is greater than that of the polypropylene composition B. i The polypropylene composition B' i The melting point of the polypropylene composition B; i Polypropylene composition B' i The melting point of each is greater than that of the adjacent polypropylene composition B'. i-1 Polypropylene composition B i-1 Its melting point.

[0008] In a preferred embodiment of the present invention, polypropylene composition A i The melting point of polypropylene composition B i The difference in melting points, polypropylene composition A i The melting point of polypropylene composition B' i The difference in melting point between each is greater than or equal to 10°C, preferably greater than or equal to 20°C; more preferably 20-60°C.

[0009] According to the present invention, A1……A i ...A nIt can be the same material or different materials; this invention does not have any particular limitations, as long as A i The melting point is greater than that of the polypropylene composition B. i Polypropylene composition B i-1 The melting points of all these factors can achieve better technical results.

[0010] In a preferred embodiment of the present invention, polypropylene composition B i Polypropylene composition B' i The melting point of each of the adjacent polypropylene compositions B' i-1 Polypropylene composition B i-1 The difference in melting points may be the same or different, each ranging from 1 to 40°C, preferably from 1 to 10°C, and more preferably from 1 to 5°C.

[0011] According to the present invention, the total number of layers in the polypropylene sheet unit is 2n-1. The present invention has a wide range of options for the total number of layers in the polypropylene sheet unit. In a preferred embodiment of the present invention, 2≤n≤100, and more preferably, 2≤n≤50.

[0012] According to the present invention, in each polypropylene sheet unit, the core layer A i The thickness ratio can be selected over a wide range. In a preferred embodiment of the present invention, based on the total thickness of each polypropylene sheet unit, the core layer A in each polypropylene sheet unit... i The thickness accounts for 51%-89% of the total thickness, preferably 71%-89%, and more preferably 71%-80%. Core layer A i Outer B on both sides i and B' i The thickness can be the same or different, but the same is preferred.

[0013] The thickness of each polypropylene sheet unit can be selected within a wide range. In a preferred embodiment of the present invention, the thickness of each polypropylene sheet unit is 10-1000 μm, preferably 30-500 μm, and more preferably 50-300 μm.

[0014] According to the present invention, core layer A i Outer layer B i B i The thickness can be controlled by the extruder melt pump during the processing.

[0015] According to the present invention, polypropylene composition A i Including but not limited to one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; polypropylene composition B iIncluding but not limited to one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene, as well as thermal bonding reinforcing agent y i .

[0016] According to the present invention, the polypropylene composition A i The range of materials is relatively wide. In a preferred embodiment of the present invention, the polypropylene composition A... i This includes one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene.

[0017] According to the present invention, the polypropylene composition B i B' i Each comprises one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; preferably, the polypropylene composition B i and / or polypropylene composition B' i It also contains thermal bonding enhancer y i .

[0018] In a more preferred embodiment of the present invention, polypropylene composition A i Including homopolymer polypropylene a i Impact-resistant copolymer polypropylene b i In a further, more preferred embodiment of the invention, the polypropylene composition A is used. i Based on the total weight, the polypropylene composition A i Includes 50-99 wt% homopolymer polypropylene a i 1-50wt% impact-resistant copolymer polypropylene b i Further preferably, the polypropylene composition A i Includes 70-90 wt% homopolymer polypropylene a i 10-30wt% impact-resistant copolymer polypropylene b i .

[0019] In a more preferred embodiment of the present invention, the polypropylene composition B i The polypropylene composition B' i Each includes random copolymer polypropylene x i and thermal bonding enhancer y i Preferably, the polypropylene composition B is used. i The polypropylene composition B' i Based on their respective total weights, the polypropylene composition B i The polypropylene composition B' i Each comprises 70-99 wt% random copolymer polypropylene. i 1-30wt% thermal bonding enhancer iPreferably, the polypropylene composition B i Includes 80-90 wt% random copolymer polypropylene x i 10-20wt% of thermal bonding reinforcing agent i .

[0020] According to the present invention, the homopolymer polypropylene a i With a wide range of choices, in a preferred embodiment of the present invention, the homopolymer polypropylene a i Its melting point is 150-170℃, and / or its isotacticity (mm) is not less than 96%.

[0021] According to the present invention, the homopolymer polypropylene a i The melt flow rate has a wide selection range. Preferably, the homopolymer polypropylene a i The melt flow rate at 190℃ and 2.16kg load is 0.5-50g / 10min, preferably 1-20g / 10min, and more preferably 2.5-18g / 10min.

[0022] According to the present invention, the impact-resistant copolymer polypropylene b i With a wide range of options, in a preferred embodiment of the present invention, the impact-resistant copolymer polypropylene b i The melting point is 150-170℃, the monomer of the impact-resistant copolymer polypropylene copolymerized with propylene is ethylene or butene, selected as butene, and / or, the cantilever beam impact strength of the impact-resistant copolymer polypropylene is not less than 20KJ / m. 2 (23℃).

[0023] According to the present invention, the impact-resistant copolymer polypropylene b i The melt flow rate has a wide selection range. Preferably, the impact-resistant copolymer polypropylene b i The melt flow rate at 190℃ and 2.16kg load is 0.5-50g / 10min, preferably 1-20g / 10min, and more preferably 2.5-18g / 10min.

[0024] According to the inventor's research, when polypropylene composition A i When the melt flow rate and polymer composition ratio of the raw materials used are within the preferred range, the impact-resistant copolymer polypropylene b in the composition... i It can effectively absorb impact energy, meeting the requirements for impact performance and giving the sheet material good impact resistance. Meanwhile, due to the homopolymer polypropylene a... i The medium and large molecular chains are relatively regular and crystallize during the sheet preparation process, thus the sheet also has good tensile properties.

[0025] In a preferred embodiment of the present invention, the polypropylene composition Ai It also includes a β-crystal nucleating agent; preferably, 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.

[0026] According to the present invention, the amount of β-crystal nucleating agent can be selected over a wide range. Preferably, the amount of β-crystal nucleating agent is selected from the polypropylene composition A. i The total amount is 100 parts by weight, of the polypropylene composition A i 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.

[0027] In a preferred embodiment of the present invention, the random copolymer polypropylene x i Its melting point is 110-150℃, and x i Its melting point is greater than x i-1 The melting point, preferably a difference of 1-40℃, more preferably 1-10℃, and most preferably 1-5℃; preferably, the random copolymer polypropylene x i It is a copolymer of propylene and ethylene and / or butene, preferably an ethylene-propylene-butene terpolymer and / or a propylene-ethylene binary copolymer.

[0028] According to the present invention, the random copolymer polypropylene x i The melt flow rate has a wide selection range. Preferably, the melt flow rate at 190℃ and 2.16kg load is 0.5-50g / 10min, more preferably 1-20g / 10min, and even more preferably 3-18g / 10min.

[0029] In a preferred embodiment of the present invention, the heat-reducing adhesive y i The melting point or viscous flow temperature is 70-110℃. And / or, the thermal adhesion enhancer y i The agent is selected from one or more of polyolefin elastomers, ethylene propylene diene monomer (EPDM) rubber, SEBS, SBS, EVA, and petroleum resins; preferably, the thermal bonding reinforcing agent y i It is a polyolefin elastomer and / or petroleum resin.

[0030] In a preferred embodiment of the present invention, the polyolefin elastomer is preferably a copolymer elastomer of ethylene and propylene and / or α-olefin, wherein the α-olefin is preferably a C4-C12 α-olefin, more preferably 1-butene and / or 1-octene; and / or, the petroleum resin is a C5 and / or C9 hydrogenated petroleum resin with a softening point of 100-150°C; preferably a cyclopentadiene type resin.

[0031] According to the present invention, the thermal bonding enhancer y i The melt flow rate has a wide selection range; preferably, the thermal adhesion enhancer y i 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.

[0032] According to the inventor's research, when polypropylene composition B i and polypropylene composition B' i When the respective polymer composition ratios are within the above-mentioned preferred ranges, the low-melting-point random copolymer polypropylene x in the composition i and thermal bonding enhancer y i It can significantly reduce hot-pressing temperature and widen the hot-pressing temperature window, and the thermal bonding enhancer y i It provides good adhesion to the sheet and further improves the interlayer peel strength.

[0033] According to the inventor's research, when polypropylene composition A i Combination B with polypropylene i and polypropylene composition B' i Their respective polymer composition ratios and polymer composition A i When the thickness distribution is within the above-mentioned 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.

[0034] According to the present invention, the polypropylene sheet can be a film or have a certain thickness. In the present invention, polypropylene film is one form of polypropylene sheet.

[0035] According to the present invention, the polypropylene sheet unit is a polypropylene sheet and / or a polypropylene fabric; the polypropylene sheet unit can be a polypropylene sheet or a polypropylene fabric. In a preferred embodiment of the present invention, the polypropylene sheet unit is a polypropylene sheet or a polypropylene fabric.

[0036] In a preferred embodiment of the present invention, the polypropylene sheet is made by comprising a polypropylene composition A i Polypropylene composition B i and polypropylene composition B' i The components are co-extruded together.

[0037] In a preferred embodiment of the present invention, the polypropylene fabric is prepared by the following method: firstly, a polypropylene composition A is prepared... i Polypropylene composition B i Polypropylene composition B' iThe components are co-extruded to obtain a polypropylene sheet, and then the polypropylene sheet is woven to obtain the polypropylene fabric; preferably, the polypropylene fabric has a three-dimensional structure of plain weave, twill weave and / or satin weave.

[0038] According to the present invention, preferably, the polypropylene sheet units are connected by thermoforming.

[0039] In a preferred embodiment of the present invention, the polypropylene composite material has at least one of the following characteristics:

[0040] Longitudinal tensile strength ≥160MPa, preferably ≥180MPa; interlaminar peel strength ≥1.3N / mm, preferably ≥1.5N / mm.

[0041] 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.

[0042] When the polypropylene composite material is obtained by hot pressing five polypropylene sheet units and the thickness of the polypropylene composite material is about 390 μm, the drop hammer impact strength is ≥42 J, preferably ≥45 J.

[0043] 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.

[0044] The second objective of this invention is to provide a method for preparing the polypropylene composite material described above, comprising: preparing 2n-1 polypropylene composite materials with a structure of B... i A i B' i The polypropylene sheet unit according to B n A n B' n ...B i A i B' i ...B2A2B'2, B1A1B'1, B2A2B'2...B i A i B' i ...B n A n B' n The layers are stacked sequentially, followed by a hot-pressing fusion process.

[0045] In a preferred embodiment of the present invention, the following steps are included:

[0046] (1) Polypropylene composition A iPolypropylene composition B i and polypropylene composition B' i According to B i A i B' i The structure is co-extruded, cast or calendered, and stretched to obtain polypropylene sheets;

[0047] (2) Optionally, the polypropylene sheet is slit and then woven to obtain a structure of B. i A i B' i Polypropylene fabric;

[0048] (3) The polypropylene sheet and / or the polypropylene fabric are sequentially stacked and hot-pressed together, and then cooled and shaped to form a polypropylene composite material.

[0049] In a preferred embodiment of the present invention, in step (1), the polypropylene composition A i The preparation involves melt blending the raw materials, such as at least one of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene. The polypropylene composition A... i The conditions and equipment for melt blending are the same as those for melt blending of polyolefins in the prior art. Preferably, the melting temperature is 150-170℃ and the equipment is preferably a twin-screw extruder.

[0050] In a preferred embodiment of the present invention, in step (1), the polypropylene composition B i The preparation includes melt blending the raw materials, such as at least one of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; the polypropylene composition B i The conditions and equipment for melt blending are the same as those for melt blending of polyolefins in the prior art. Preferably, the melting temperature is 120-170°C and the equipment is preferably a twin-screw extruder.

[0051] In a preferred embodiment of the present invention, in step (1), the temperatures of co-extrusion molding and casting are independently selected from 200-240°C; and / or, the temperature of the calendering roll is 50-70°C.

[0052] 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 / or a stretching ratio of 1-15 times, preferably 2-9 times.

[0053] In a preferred embodiment of the present invention, the width of the polypropylene sheet obtained in step (1) is 2-5 mm.

[0054] In a preferred embodiment of the present invention, in step (3): the hot pressing conditions include: hot pressing temperature of 115-170℃, preferably 115-159℃, more preferably 140-159℃; hot pressing pressure of 2-10MPa; preheating time of 5-600s; and hot pressing time of 1-600s, preferably 10-500s.

[0055] In a preferred embodiment of the present invention, the cooling and shaping pressure is 2-8 MPa, and the cooling time is 30s-700s.

[0056] In a preferred embodiment of the present invention, adjacent polypropylene fabrics of the stack are placed at 0-90° between warp directions; and / or, adjacent polypropylene sheets of the stack are placed at 0-90° along their respective machine directions, which are the stretching directions (MD).

[0057] In a more preferred embodiment of the present invention, the method for preparing the polypropylene composite material includes the following steps:

[0058] Step a: Take polypropylene composition A i Polypropylene composition B i and polypropylene composition B' i According to B i A i B' i The structure is co-extruded and cast or calendered to obtain polypropylene co-extruded sheets; preferably, the extrusion casting or calendering temperature is 200-230℃, and the calendering roll temperature is 50-70℃;

[0059] Step b: The polypropylene co-extruded sheet is subjected to solid-state stretching at a certain temperature to obtain a polypropylene stretched film or stretched sheet; preferably, the stretching temperature is 90-165℃, more preferably 90-140℃, and even more preferably 90-119℃, and the stretching ratio is 1-15 times.

[0060] Step c: Cut the polypropylene stretched film or 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 fabric structure includes, but is not limited to, plain weave, twill weave, satin weave and / or other three-dimensional polypropylene fabrics.

[0061] Step d: Stack the polypropylene stretched film, sheet, or fabric sequentially, from bottom to top as B n A n B' n ...B i A i B' i ...B2A2B'2, B1A1B'1, B2A2B'2...Bi A i B' i ...B n A n B' n The total number of layers is 2n-1, where n>=2. The polypropylene sheets or fabrics are hot-pressed and fused together, then cooled and shaped to form a polypropylene composite material. The preferred hot-pressing temperature is 110-180℃, more preferably 115-170℃, and even more preferably 130-160℃; the hot-pressing pressure is 2-10MPa, the preheating time is 5-600s, the hot-pressing time is 1-600s, preferably 10-500s, the cooling pressure is 2-8MPa, and the cooling time is 30s-700s. Preferably, the polypropylene sheets in the polypropylene composite material can be placed at 0-90° to the machine direction, and the polypropylene fabrics can be placed at 0-90° between the warp directions.

[0062] A third objective of this invention is to provide a continuous hot-pressing molding system for polypropylene composite materials, such as... Figure 1 As shown, the continuous hot pressing system for the composite material includes a preheater 1, a tracked continuous planar hot press 2, a tracked continuous planar cooling press 3, a sheet cutting machine 4, and a sheet stacking machine 5 arranged in sequence.

[0063] Preferably, the tracked continuous planar hot press 3 includes a preheating unit 6, an independent heating and pressurizing unit 7, an air-cooling unit 8, and a lifting mechanism 9.

[0064] 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, and the hot pressing process is performed continuously, preferably as follows: Figure 1 As shown, a continuous hot-pressing composite material molding equipment is used, consisting of a preheating machine 1, a tracked continuous planar hot press 2, a tracked continuous planar cooling press 3, a sheet cutting machine 4, and a sheet stacking machine 5. Preferably, the tracked continuous planar hot press 2 has a preheating unit 6, an independent heating and pressurizing unit 7, an air-cooling unit 8, and a lifting mechanism 9. In the preparation process, the polypropylene stretched film, sheet, or / and fabric are sequentially layered and preheated by the preheating machine 1. The preheated sample is then sequentially passed through the tracked planar hot press 2 for hot pressing and fusion, and then cooled and shaped by the tracked continuous planar cooling press 3 to produce a polypropylene composite material, i.e., a laminated hot-pressed product. Afterwards, the product is sliced ​​by the sheet cutting machine 4 as needed, and then stacked and arranged by the sheet stacking machine 5. The hot-pressing temperature is controlled by the preheating unit 6, the independent heating and pressurizing unit 7, and the air-cooling unit 8 in the tracked planar hot press 2, and the hot-pressing pressure is controlled by the lifting mechanism 9.

[0065] According to the inventors' research, when the preparation process parameters are within the above-mentioned preferred range, and more preferably when the preparation equipment is used to prepare the polymer composite material, the polymer composite material has better tensile strength, impact performance and interlaminar peel strength.

[0066] The fourth objective of this invention is to provide an application of the polypropylene composite material described above and the polypropylene composite material prepared by the preparation method described above in the fields of consumer goods, automobile manufacturing, sports protection, and military materials.

[0067] 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.

[0068] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0069] (1) The polypropylene composite material of the present invention has a melting point gradient structure. Under this specific structure, the inventors of the present invention surprisingly discovered that the resulting polypropylene composite material has good tensile strength, impact performance and interlaminar peel strength.

[0070] (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. The hot pressing temperature range can effectively reduce the energy consumption of equipment and the damage to the composite material caused by high temperature operation. At the same time, when prepared at a lower hot pressing temperature, it still has good interlayer peel strength.

[0071] (3) This preparation method can reduce the hot pressing operation time, while improving production efficiency and reducing production energy consumption.

[0072] (4) The present invention adopts a melting point gradient structure design, which reduces the hot pressing temperature and widens the hot pressing temperature range to 70°C; effectively reducing equipment energy consumption and damage to composite materials under high temperature operation. Attached Figure Description

[0073] Figure 1 This is a schematic diagram of the arrangement of processing equipment used in a preferred embodiment of the present invention.

[0074] 1 is a preheating machine; 2 is a crawler-type continuous flat hot press; 3 is a crawler-type continuous flat cooling press; 4 is a sheet cutting machine; 5 is a sheet stacking machine; the crawler-type continuous flat hot press 2 has a preheating unit 6; an independent heating and pressurizing unit 7; an air cooling unit 8; and a lifting mechanism 9. Detailed Implementation

[0075] The present invention will now be described in detail with reference to the accompanying drawings and 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.

[0076] The properties of the polypropylene composition and sheet were tested according to the following methods, and the product test results are shown in Table 1:

[0077] (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;

[0078] (2) The melting point of the material was determined by the method of GB / T 28724-2012.

[0079] (3) Sheet tensile strength: determined according to the method specified in GB / T1040.1-2018;

[0080] (4) Drop hammer impact strength: determined according to the method specified in GB / T14153-1993;

[0081] (5) Interlayer peel strength: The test shall be conducted in accordance with the method specified in QB / T2358-98.

[0082] 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.

[0083] Example 1

[0084] 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.

[0085] (1) Preparation of polypropylene composition A:

[0086] Component a is a homopolymer polypropylene self-produced by the Beijing Research Institute of Chemical Industry of 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 of Sinopec, with an ethylene content of 11 wt%, a melting point of 155℃, and a cantilever beam impact strength of 23 KJ / m. 2(23℃), melt flow rate is 2.0 g / 10 min. The above-prepared components are weighed and mixed according to the proportions, wherein the mass fraction Wa of component a is 80 parts by weight and the mass fraction Wb of component b is 20 parts by weight.

[0087] Add 0.05 parts by weight of β-crystal nucleating agent of grade VP101B. Then, add the mixture to a high-speed mixer and mix evenly. Then, add the mixed material to the feeder of a twin-screw extruder manufactured by W&P. The material enters the twin screw through the feeder. During the processing, the screw temperature is maintained between 200-230°C. After being melted and mixed evenly by the screw, extruded, granulated and dried, polypropylene composition granules A are obtained. The melting point of polypropylene composition granules A is tested to be 157°C.

[0088] (2) Polypropylene composition B i Preparation:

[0089] Component x1 is a random copolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer with a melt flow rate of 8.1 g / 10 min and a melting point of 130 °C; Component x2 is a random copolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer with a melt flow rate of 7.2 g / 10 min and a melting point of 135 °C; Component x3 is a random copolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer with a melt flow rate of 6.6 g / 10 min and a melting point of 140 °C; Component y is a polyolefin elastomer of grade 6102, purchased from ExxonMobil, which is an ethylene-propylene copolymer.

[0090] The components obtained above are weighed and mixed according to the specified proportions, wherein component x i mass parts Wx i The weight percentage of component y is 85 parts by weight, and the weight percentage of component y (Wy) is 15 parts by weight. Other steps are the same as in step (1), and the final polypropylene composition B is obtained. i Granular material (i.e., x) i +y=B i (i = 1, 2, 3), after testing, the melting point of B1 is 127℃, the melting point of B2 is 132℃, and the melting point of B3 is 138℃.

[0091] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0092] The polypropylene composition A and polypropylene composition B obtained in steps (1) and (2) above are used. i The granules are dried, and then polypropylene composition A is added to the core layer extruder of a multilayer extrusion calender, and polypropylene composition B is added. iThe granules are fed into the upper and lower surface extruders of a multi-layer extrusion casting machine. After being co-extruded and compounded through the extruder die, the granules pass sequentially through calendering rolls and traction rolls, followed by solid-phase stretching, edge trimming, and winding to produce sheets B1AB1, B2AB2, and B3AB3, respectively. The extrusion casting temperature is 230℃, and the calendering roll temperature is 58℃. The solid-phase stretching process is carried out at 140℃, with a stretching rate of 2 m / min and a stretch ratio of 7.

[0093] A composite film (polypropylene sheet) made by stretching and then winding consists of an upper surface layer (outer film B). i ), core layer (film A) and lower surface layer (outer film B) i The composite film is composed of layers A and B. The composite film is 80 μm thick, with layer A accounting for 80% of the total thickness of the sheet.

[0094] (4) Preparation of polypropylene fabric:

[0095] The three-layer co-extruded polypropylene sheet obtained in step (3) above is cut with a high-speed slitting machine with multiple blades to obtain oriented polypropylene flat strips with a width of 3mm; the oriented flat strips are woven with commercial weaving machines according to the designed fabric structure to obtain plain weave polypropylene fabrics B1AB1, B2AB2, and B3AB3.

[0096] (5) Preparation of polypropylene composite materials:

[0097] The polypropylene fabrics obtained in step (4) were stacked sequentially from bottom to top as follows: B3A3B3, B2A2B2, B1A1B1, B2A2B2, and B3A3B3, for a total of 5 layers. The stacked polypropylene fabrics were then hot-pressed together and cooled to form a polypropylene composite material. The polypropylene fabrics were placed at a 90° angle between the warp and weft directions. The hot-pressing conditions were: temperature 145℃, hot-pressing pressure 5MPa, preheating time 90s, hot-pressing time 90s, and cooling time 300s. The thickness of the prepared polypropylene composite material was 391μm.

[0098] Example 2

[0099] 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.

[0100] (1) Preparation of polypropylene composition A:

[0101] 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 an ethylene content of 8 wt%, a melting point of 155℃, a melt flow rate of 3.2 g / 10 min, and a cantilever beam impact strength of 25 KJ / m. 2 (23℃). Weigh and mix the components obtained above according to the proportions, wherein the mass fraction Wa of component a is 70 parts by weight, and the mass fraction Wb of component b is... n The sample consisted of 30 parts by weight. 0.05 parts by weight of β-crystal nucleating agent (brand name VP101B) was 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 being melted and mixed evenly by the screws, extruded, granulated, and dried, polypropylene composition granules A were obtained. The melting point of polypropylene composition granules A was tested to be 161°C.

[0102] (2) Polypropylene composition B i Preparation:

[0103] Component x1 is a random copolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer with a melting point of 128℃ and a melt flow rate of 7.8 g / 10 min; Component x2 is a random copolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer with a melting point of 134℃ and a melt flow rate of 6.9 g / 10 min; Component x3 is a random copolymer polypropylene produced by Sinopec Beijing Research Institute of Chemical Industry, which is an ethylene-propylene-butene terpolymer with a melting point of 142℃ and 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, a melting point of 105℃, and a melt flow rate of 9 g / 10 min under a 2.16 kg load.

[0104] The components obtained above are weighed and mixed according to the specified proportions, wherein component x i mass parts Wx i The weight of component y is 80 parts by weight, and the weight of component y (Wy) is 20 parts by weight. Other steps are the same as in step (1), and finally polypropylene composition B is obtained. i Granular material (i.e., x) i +y=B i (i = 1, 2, 3), after testing, the melting point of B1 is 126℃, the melting point of B2 is 133℃, and the melting point of B3 is 140℃.

[0105] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0106] The preparation process is the same as step (3) in Example 1.

[0107] (4) Preparation of polypropylene fabric:

[0108] The preparation process is the same as step (4) of Example 1.

[0109] (5) Preparation of polypropylene composite materials:

[0110] The preparation process is the same as step (5) in Example 1.

[0111] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0112] Example 3

[0113] 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.

[0114] (1) Preparation of polypropylene composition A:

[0115] 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 a β-crystal nucleating agent (VP101B) are added. Polypropylene composition A granules are obtained, and the melting point of polypropylene composition granules A is measured to be 158°C.

[0116] (2) Polypropylene composition B i Preparation:

[0117] Same as in Example 1, wherein the corresponding component x i mass parts Wx i The final polypropylene composition B is obtained by using 90 parts by weight of component y and 10 parts by weight of component y. i Granular material (i.e., x) i +y=B i (i = 1, 2, 3), after testing, the melting point of B1 is 128℃, the melting point of B2 is 134℃, and the melting point of B3 is 139℃.

[0118] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0119] The preparation process is the same as step (3) in Example 1.

[0120] (4) Preparation of polypropylene fabric:

[0121] The preparation process is the same as step (4) of Example 1.

[0122] (5) Preparation of polypropylene composite materials:

[0123] The preparation process is the same as step (5) in Example 1.

[0124] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0125] Example 4

[0126] 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.

[0127] (1) Preparation of polypropylene composition A:

[0128] The preparation process is the same as step (1) in Example 1.

[0129] (2) Polypropylene composition B i Preparation:

[0130] The preparation process is the same as step (2) of Example 1.

[0131] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0132] The main steps are the same as in Example 1. The polypropylene sheet is 80 μm thick, and the thickness of the film layer A accounts for 90% of the total sheet thickness.

[0133] (4) Preparation of polypropylene fabric:

[0134] The preparation process is the same as step (4) of Example 1.

[0135] (5) Preparation of polypropylene composite materials:

[0136] The preparation process is the same as step (5) in Example 1.

[0137] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0138] Example 5

[0139] 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.

[0140] (1) Preparation of polypropylene composition A:

[0141] The preparation process is the same as step (1) in Example 1.

[0142] (2) Polypropylene composition B i Preparation:

[0143] The preparation process is the same as step (2) of Example 1.

[0144] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0145] The main steps are the same as in Example 1. The polypropylene sheet is 80 μm thick, and the thickness of the film layer A accounts for 70% of the total sheet thickness.

[0146] (4) Preparation of polypropylene fabric:

[0147] The preparation process is the same as step (4) of Example 1.

[0148] (5) Preparation of polypropylene composite materials:

[0149] The preparation process is the same as step (5) in Example 1.

[0150] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0151] Example 6

[0152] 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.

[0153] (1) Preparation of polypropylene composition A:

[0154] The preparation process is the same as step (1) in Example 1.

[0155] (2) Polypropylene composition B i Preparation:

[0156] The preparation process is the same as step (2) of Example 1.

[0157] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0158] The preparation process is the same as step (3) in Example 1.

[0159] (4) Preparation of polypropylene fabric:

[0160] 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.

[0161] (5) Preparation of polypropylene composite materials:

[0162] The preparation process is the same as step (5) in Example 1.

[0163] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0164] Example 7

[0165] 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.

[0166] (1) Preparation of polypropylene composition A:

[0167] The preparation process is the same as step (1) in Example 1.

[0168] (2) Polypropylene composition B i Preparation:

[0169] The preparation process is the same as step (2) of Example 1.

[0170] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0171] The main preparation process is the same as step (3) in Example 1. The sheet stretching ratio is 10 times.

[0172] (4) Preparation of polypropylene fabric:

[0173] The preparation process is the same as step (4) of Example 1.

[0174] (5) Preparation of polypropylene composite materials:

[0175] The preparation process is the same as step (5) in Example 1.

[0176] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0177] Example 8

[0178] 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.

[0179] (1) Preparation of polypropylene composition A:

[0180] The preparation process is the same as step (1) in Example 1.

[0181] (2) Polypropylene composition B i Preparation:

[0182] The preparation process is the same as step (2) of Example 1.

[0183] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0184] The preparation process is the same as step (3) in Example 1.

[0185] (4) Preparation of polypropylene fabric:

[0186] The preparation process is the same as step (4) of Example 1.

[0187] (5) Preparation of polypropylene composite materials:

[0188] 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.

[0189] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0190] Example 9

[0191] 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.

[0192] (1) Preparation of polypropylene composition A:

[0193] The preparation process is the same as step (1) in Example 1.

[0194] (2) Polypropylene composition B i Preparation:

[0195] The preparation process is the same as step (2) of Example 1.

[0196] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0197] The preparation process is the same as step (3) in Example 1.

[0198] (4) Preparation of polypropylene fabric:

[0199] The preparation process is the same as step (4) of Example 1.

[0200] (5) Preparation of polypropylene composite materials:

[0201] 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.

[0202] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0203] Example 10

[0204] 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.

[0205] (1) Preparation of polypropylene composition A:

[0206] The preparation process is the same as step (1) in Example 1.

[0207] (2) Preparation of polypropylene composition B:

[0208] The main preparation process is the same as step (2) in Example 1. The difference is that component B... i and x i The materials selected are as follows:

[0209] Component x1 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 110℃; Component x2 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 115℃; Component x3 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 120℃; Component x4 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 125℃; Component x5 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer. The material has a melting point of 130℃; component x6 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry of Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 135℃; component x7 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry of Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 140℃; component x8 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry of Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 145℃; component x9 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry of Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 150℃; among them, the melt flow rate of components x1-x9 is 1-20 g / 10 min.

[0210] Finally, polypropylene composition B was obtained. i Granular material (i.e., x) i +y=B i (i = 1, 2, 3, 4, 5, 6, 7, 8, 9). After testing, the melting point of B1 is 110℃, the melting point of B2 is 113℃, the melting point of B3 is 117℃, the melting point of B4 is 123℃, the melting point of B5 is 127℃, the melting point of B6 is 133℃, the melting point of B7 is 137℃, the melting point of B8 is 142℃, and the melting point of B9 is 148℃.

[0211] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0212] The preparation process is the same as step (3) in Example 1.

[0213] (4) Preparation of polypropylene fabric:

[0214] The preparation process is the same as step (4) of Example 1.

[0215] (5) Preparation of polypropylene composite materials:

[0216] The polypropylene fabrics obtained in step (4) were stacked sequentially from bottom to top as follows: B9A9B9…B3A3B3, B2A2B2, B1A1B1, B2A2B2, B3A3B3,…B9A9B9, for a total of 17 layers. The stacked polypropylene fabrics were then hot-pressed together and cooled to form a polypropylene composite material. The polypropylene fabrics were placed at a 90° angle between the warp and weft directions. The hot-pressing conditions were: temperature 150℃, hot-pressing pressure 5MPa, preheating time 300s, hot-pressing time 180s, and cooling time 600s. The resulting polypropylene composite material had a thickness of 1.24mm.

[0217] Example 11

[0218] 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.

[0219] (1) Preparation of polypropylene composition A:

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

[0221] (2) Preparation of polypropylene composition B:

[0222] The preparation process is the same as step (2) of Example 1.

[0223] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0224] The preparation process is the same as step (3) in Example 1.

[0225] (4) Preparation of polypropylene fabric:

[0226] The preparation process is the same as step (4) of Example 1.

[0227] (5) Preparation of polypropylene composite materials:

[0228] The main steps are the same as in Example 1. The difference is that the hot-pressing conditions are changed to: temperature 150℃, hot-pressing pressure 8MPa, preheating time 180s, hot-pressing time 180s, and cooling time 700s. The thickness of the prepared polypropylene composite material is 387μm.

[0229] Example 12

[0230] 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.

[0231] (1) Preparation of polypropylene composition A:

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

[0233] (2) Preparation of polypropylene composition B:

[0234] The main preparation process is the same as step (2) of Example 1, except that component B... i and x i The materials selected are as follows:

[0235] Component x1 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 110℃; component x2 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 130℃; component x3 is a random copolymer polypropylene produced by the Beijing Research Institute of Chemical Industry, Sinopec, which is an ethylene-propylene-butene terpolymer with a melting point of 150℃. The melt flow rates of components x1-x3 are all 1-20 g / 10 min.

[0236] Finally, polypropylene composition B was obtained. i Granular material (i.e., x) i +y=B i (i = 1, 2, 3), after testing, the melting point of B1 is 110℃, the melting point of B2 is 128℃, and the melting point of B3 is 147℃.

[0237] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0238] The preparation process is the same as step (3) in Example 1.

[0239] (4) Preparation of polypropylene fabric:

[0240] The preparation process is the same as step (4) of Example 1.

[0241] (5) Preparation of polypropylene composite materials:

[0242] The preparation process is the same as step (5) in Example 1.

[0243] The thickness of the prepared polypropylene composite material is similar to that of Example 1.

[0244] Example 13

[0245] 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.

[0246] (1) Preparation of polypropylene composition A:

[0247] The preparation process is the same as step (1) in Example 1.

[0248] (2) Preparation of polypropylene composition B:

[0249] The preparation process is the same as step (2) of Example 1.

[0250] (3) Preparation of three-layer co-extruded polypropylene sheets:

[0251] The preparation process is the same as step (3) in Example 1.

[0252] (4) Preparation of polypropylene composite materials:

[0253] Instead of preparing polypropylene fabric, the three-layer co-extruded polypropylene sheet obtained in step (3) is used to replace the polypropylene fabric obtained in step (4) of Example 1 and is sequentially stacked and hot-pressed according to step (5) of Example 1.

[0254] The thickness of the resulting polypropylene composite material is similar to that of Example 1.

[0255] Comparative Example 1

[0256] Co-extruded polypropylene sheets were prepared according to the method of Example 1, except that component Bi was selected as follows: component x1 was random copolymer polypropylene self-made by Sinopec Beijing Chemical Research Institute, which was an ethylene-propylene-butene terpolymer with a melting point of 140°C; component x2 was random copolymer polypropylene self-made by Sinopec Beijing Chemical Research Institute, which was an ethylene-propylene-butene terpolymer with a melting point of 135°C; component x3 was random copolymer polypropylene self-made by Sinopec Beijing Chemical Research Institute, which was an ethylene-propylene-butene terpolymer with a melting point of 130°C; the melt flow rate of components x1-x3 was 2-10 g / 10 min.

[0257] Finally, polypropylene composition B was obtained. i Granular material (i.e., x) i +y=B i (i = 1, 2, 3), after testing, the melting point of B1 is 138℃, the melting point of B2 is 132℃, and the melting point of B3 is 127℃.

[0258] Comparative Example 2

[0259] Three-layer co-extruded polypropylene sheets were prepared according to the method of Example 1. Only polypropylene composition B... i It contains only component y.

[0260] Polypropylene fabrics and polypropylene composites were prepared according to the method of Example 1.

[0261] Comparative Example 3

[0262] 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.

[0263] Comparative Example 4

[0264] 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.

[0265] Experimental Example

[0266] 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:

[0267] (1) Sheet tensile strength: determined according to the method specified in GB / T1040.1-2018;

[0268] (2) Drop hammer impact strength: determined according to the method specified in GB / T14153-1993;

[0269] (3) Interlayer peel strength: The strength was determined according to the method specified in QB / T2358-98. Among them, the thickness of the polypropylene composite materials obtained in Examples 1-9, 12, 13 and Comparative Examples 1-4 were all similar, around 390 μm, and all within the range of 390 μm ± 10 μm.

[0270] Table 1

[0271] serial number Tensile strength (MPa) Drop hammer impact strength (J) Peel strength (N / mm) Example 1 191 46.91 1.53 Example 2 183 45.72 1.59 Example 3 200 45.48 1.51 Example 4 202 44.04 1.32 Example 5 168 44.75 1.63 Example 6 172 46.11 1.37 Example 7 258 42.17 1.38 Example 8 176 43.59 1.45 Example 9 161 42.14 1.42 Example 10 168 81.62 1.49 Example 11 165 44.43 1.53 Example 12 163 41.21 1.65 Example 13 212 45.67 1.61 Comparative Example 1 131 30.89 0.78 Comparative Example 2 181 42.55 1.12 Comparative Example 3 183 40.16 0.88 Comparative Example 4 106 42.23 2.09

[0272] The results of the examples in Table 1 show that the polypropylene composite material with a melting point gradient structure prepared according to the present invention has both good tensile properties and impact resistance, and also has good interlaminar peel strength at a relatively low hot-pressing temperature.

[0273] The longitudinal (MD) tensile strength of the polypropylene composite material with melting point gradient structure described in this invention is ≥160MPa, and the interlaminar peel strength is ≥1.3N / mm; when the composite material is made of only 5 layers of polypropylene fabric hot-pressed together and the thickness is only about 390μm, the drop hammer impact strength is ≥42J.

[0274] As can be seen from the preferred embodiments 1-3, the longitudinal (MD) tensile strength of the polypropylene composite material with melting point gradient structure prepared by the present invention is ≥180MPa, and the interlaminar peel strength is ≥1.5N / mm; when the composite material is only 5 layers of polypropylene fabric hot-pressed together and only about 390μm thick, the drop hammer impact strength is ≥45J.

[0275] As can be seen from Comparative Examples 1-4, polypropylene composite materials prepared using methods outside the scope of this invention will lead to a decrease in the properties of laminated polypropylene sheets or fabrics, resulting in a significant decrease in the tensile strength, impact properties, or interlaminar peel strength of the obtained polypropylene composite materials.

[0276] 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.

[0277] 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 comprising a plurality of sequentially stacked polypropylene sheet units; each polypropylene sheet unit including a core layer A i and located in core layer A i Outer B on both sides i B' i The structure is B i A i B' i The structure of the polypropylene composite material, from bottom to top, is B. n A n B' n ...B i A i B' i ...B2A2B'2, B1A1B'1, B2A2B'2...B i A i B' i ...B n A n B' n The total number of layers in the polypropylene sheet unit is 2n-1; i and n are both integers not less than 2, and i≤n; in, Core layer A in a polypropylene sheet unit i Composition A containing polypropylene i Outer layer B i With outer layer B' i Whether the composition is the same or different, each composition corresponds to a polypropylene composition B. i Polypropylene composition B' i , The polypropylene composition A i The melting point is greater than that of the polypropylene composition B. i The polypropylene composition B' i The melting point of the polypropylene composition B; i Polypropylene composition B' i The melting point of each is greater than that of the adjacent polypropylene composition B'. i-1 Polypropylene composition B i-1 The melting point; Based on the total thickness of each polypropylene sheet unit, the core layer A in each polypropylene sheet unit i The thickness accounts for 51%-89% of the total thickness.

2. The polypropylene composite material according to claim 1, characterized in that: Polypropylene Composition A i The melting point of polypropylene composition B i The difference in melting points, polypropylene composition A i The melting point of polypropylene composition B' i The difference in their melting points is greater than or equal to 10°C; and / or, Polypropylene composition B i Polypropylene composition B' i The melting point of each of the adjacent polypropylene compositions B' i-1 Polypropylene composition B i-1 The difference in their melting points may be the same or different, ranging from 1 to 40°C.

3. The polypropylene composite material according to claim 1, characterized in that: Polypropylene Composition A i The melting point of polypropylene composition B i The difference in melting points, polypropylene composition A i The melting point of polypropylene composition B' i The difference in their melting points is greater than or equal to 20°C. And / or, Polypropylene composition B i Polypropylene composition B' i The melting point of each of the adjacent polypropylene compositions B' i-1 Polypropylene composition B i-1 The difference in their melting points may be the same or different, each ranging from 1 to 10°C.

4. The polypropylene composite material according to claim 1, characterized in that: Polypropylene composition B i Polypropylene composition B' i The melting point of each of the adjacent polypropylene compositions B' i-1 Polypropylene composition B i-1 The difference in melting points may be the same or different, each ranging from 1 to 5°C.

5. The polypropylene composite material according to claim 1, characterized in that: 2≤n≤100。 6. The polypropylene composite material according to claim 1, characterized in that: 2≤n≤50。 7. The polypropylene composite material according to claim 1, characterized in that: Based on the total thickness of each polypropylene sheet unit, the core layer A in each polypropylene sheet unit i The thickness accounts for 71%-89% of the total thickness.

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

9. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composition A i Including one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; and / or, The polypropylene composition B i B' i Each includes one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene.

10. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composition B i B' i Each comprises one or more of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene, wherein the polypropylene composition B i and / or polypropylene composition B' i It also contains thermal bonding enhancer y i .

11. The polypropylene composite material according to claim 1, characterized in that: Polypropylene Composition A i Including homopolymer polypropylene a i Impact-resistant copolymer polypropylene b i .

12. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composition B i The polypropylene composition B' i Each includes random copolymer polypropylene x i and thermal bonding enhancer y i .

13. The polypropylene composite material according to claim 1, characterized in that: With the polypropylene composition A i Based on the total weight, the polypropylene composition A i Includes 50-99 wt% homopolymer polypropylene a i 1-50wt% impact-resistant copolymer polypropylene b i ; and / or, With the polypropylene composition B i The polypropylene composition B' i Based on their respective total weights, the polypropylene composition B i The polypropylene composition B' i Each comprises 70-99 wt% random copolymer polypropylene. i 1-30wt% thermal bonding enhancer i .

14. The polypropylene composite material according to claim 1, characterized in that: With the polypropylene composition A i Based on the total weight, the polypropylene composition A i Includes 70-90 wt% homopolymer polypropylene a i 10-30wt% impact-resistant copolymer polypropylene b i ; and / or, With the polypropylene composition B i The polypropylene composition B' i Based on their respective total weights, the polypropylene composition B i Includes 80-90 wt% random copolymer polypropylene x i 10-20wt% of thermal bonding reinforcing agent i .

15. The polypropylene composite material according to claim 11, characterized in that: The homopolymer polypropylene a i The melting point is 150-170℃; and / or, The homopolymer polypropylene a i The isotacticity is not less than 96%; and / or, The impact-resistant copolymer polypropylene b i The melting point is 150-170℃: and / or, The impact-resistant copolymer polypropylene b i The monomers copolymerized with propylene are ethylene or butene; and / or, The impact-resistant copolymer polypropylene b i The impact strength of the cantilever beam shall not be less than 20 KJ / m 2 .

16. The polypropylene composite material according to claim 11, characterized in that: The impact-resistant copolymer polypropylene b i The monomer copolymerized with propylene is butene.

17. The polypropylene composite material according to claim 12, characterized in that: The random copolymer polypropylene x i Its melting point is 110-150℃, and x i Its melting point is greater than x i-1 The melting point; and / or, The random copolymer polypropylene x i It is a copolymer of propylene with ethylene and / or butene.

18. The polypropylene composite material according to claim 12, characterized in that: The random copolymer polypropylene x i Its melting point is 110-150℃, and x i Its melting point is greater than x i-1 The melting point, with a difference of 1-40℃; and / or, The random copolymer polypropylene x i It is an ethylene-propylene-butene terpolymer and / or a propylene-ethylene binary copolymer.

19. The polypropylene composite material according to claim 12, characterized in that: The random copolymer polypropylene x i Its melting point is 110-150℃, and x i Its melting point is greater than x i-1 The melting point of each is 1-10℃.

20. The polypropylene composite material according to claim 12, characterized in that: The random copolymer polypropylene x i Its melting point is 110-150℃, and x i Its melting point is greater than x i-1 The melting point of each is 1-5℃.

21. The polypropylene composite material according to claim 12, characterized in that: The thermal adhesive reinforcing agent y i The melting point or viscous flow temperature is 70-110℃; and / or, The thermal adhesive reinforcing agent y i It is selected from one or more of polyolefin elastomers, ethylene propylene diene monomer (EPDM) rubber, SEBS, SBS, EVA, and petroleum resins.

22. The polypropylene composite material according to claim 12, characterized in that: The thermal adhesive reinforcing agent y i It is a polyolefin elastomer and / or petroleum resin.

23. The polypropylene composite material according to claim 22, characterized in that: The polyolefin elastomer is a copolymer elastomer of ethylene with propylene and / or α-olefins; and / or, The petroleum resin is a hydrogenated petroleum resin of C5 and / or C9.

24. The polypropylene composite material according to claim 22, characterized in that: The polyolefin elastomer is a copolymer elastomer of ethylene and propylene and / or α-olefin, wherein 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℃.

25. The polypropylene composite material according to claim 22, characterized in that: The polyolefin elastomer is a copolymer elastomer of ethylene and propylene and / or α-olefin, wherein the α-olefin is 1-butene and / or 1-octene; and / or, The petroleum resin is a C5 and / or C9 hydrogenated petroleum resin with a softening point of 100-150℃, and is a cyclopentadiene type resin.

26. The polypropylene composite material according to claim 1, characterized in that: The polypropylene composition A i Including β-crystal nucleating agents.

27. The polypropylene composite material according to claim 26, 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, With the polypropylene composition A i The total amount is 100 parts by weight, of the polypropylene composition A i The content of the β-crystal nucleating agent mentioned herein is 0.01-0.5 parts by weight.

28. The polypropylene composite material according to any one of claims 1-27, characterized in that: The polypropylene sheet unit is a polypropylene sheet and / or a polypropylene fabric.

29. The polypropylene composite material according to claim 28, characterized in that: The polypropylene sheet is made by comprising a polypropylene composition A i Polypropylene composition B i and polypropylene composition B' i The components are co-extruded together; and / or, The polypropylene fabric is prepared by the following method: firstly, a polypropylene composition A is prepared... i Polypropylene composition B i Polypropylene composition B' i Polypropylene sheets are obtained by co-extruding the inner components, and then the polypropylene sheets are woven to obtain the polypropylene fabric.

30. The polypropylene composite material according to claim 28, characterized in that: The polypropylene fabric has a three-dimensional structure of plain weave, twill weave, and / or satin weave.

31. The polypropylene composite material according to claim 28, characterized in that: The polypropylene sheet units are connected by hot-pressing.

32. A method for preparing a polypropylene composite material according to any one of claims 1-31, comprising: 2n-1 polypropylene composite materials with a structure of B... i A i B' i The polypropylene sheet unit according to B n A n B' n ...B i A i B' i ...B2A2B'2, B1A1B'1, B2A2B'2...B i A i B' i ...B n A n B' n The layers are stacked sequentially, followed by a hot-pressing fusion process.

33. The preparation method according to claim 32, characterized in that... Includes the following steps: (1) Take polypropylene composition A i Polypropylene composition B i and polypropylene composition B' i According to B i A i B' i The structure is co-extruded, cast or calendered, and stretched to obtain polypropylene sheets; (2) Optionally, the polypropylene sheet is slit and then woven to obtain a structure of B. i A i B' i Polypropylene fabric; (3) The polypropylene sheet and / or the polypropylene fabric are sequentially stacked and hot-pressed together, and then cooled and shaped to form a polypropylene composite material.

34. The preparation method according to claim 33, characterized in that: In step (1), polypropylene composition A i The preparation includes melt blending of components including at least one of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; and / or, The polypropylene composition B in step (1) i The preparation includes melt blending of components including at least one of homopolymer polypropylene, random copolymer polypropylene, and impact copolymer polypropylene; and / or, In step (1), the temperatures for extrusion molding and casting are independently selected from 200-240℃; and / or, In step (1), the temperature of the calendering roll is 50-70℃; and / or, The stretching temperature in step (1) is 90-165℃; and / or, In step (1), the stretching ratio is 1-15 times.

35. The preparation method according to claim 33, characterized in that: The stretching temperature in step (1) is 90-140℃.

36. The preparation method according to claim 33, characterized in that: The stretching temperature in step (1) is 90-119℃.

37. The preparation method according to claim 33, characterized in that: In step (3): The hot pressing conditions include: hot pressing temperature of 115-170℃; hot pressing pressure of 2-10MPa; preheating time of 5-600s; and hot pressing time of 1-600s; and / or, The cooling and shaping pressure is 2-8 MPa, and the cooling time is 30-700 seconds; and / or, The adjacent polypropylene fabrics of the stack are placed at an angle of 0-90° between the warp directions; and / or, The adjacent polypropylene sheets in the stack are placed at 0-90° along their respective machine directions.

38. The preparation method according to claim 33, characterized in that: In step (3): The hot pressing conditions include: hot pressing temperature of 115-159℃; hot pressing pressure of 2-10MPa; preheating time of 5-600s; and hot pressing time of 10-500s.

39. The preparation method according to claim 33, characterized in that: In step (3): The hot pressing conditions include: hot pressing temperature of 140-159℃; hot pressing pressure of 2-10MPa; preheating time of 5-600s; and hot pressing time of 10-500s.

40. A continuous hot pressing system for polypropylene composite materials according to any one of claims 1-31, comprising a preheater, a tracked continuous planar hot press, a tracked continuous planar cooling press, a sheet cutter, and a sheet stacker arranged in sequence. The tracked continuous planar hot press includes a preheating unit, an independent heating and pressurizing unit, an air-cooling unit, and a lifting mechanism; In the preparation of polypropylene composite materials, polypropylene sheets and / or fabrics are sequentially layered 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 the laminated hot-pressed polypropylene composite material. Subsequently, as needed, the composite material is sliced ​​using a sheet cutting machine, and then the hot-pressed products are 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 flat hot press, while the hot pressing pressure is controlled by the lifting mechanism.

41. The application of the polypropylene composite material according to any one of claims 1-31 and the polypropylene composite material prepared by the preparation method according to any one of claims 32-38 in the fields of consumer products and military materials.

42. The application according to claim 41, characterized in that: The applications are in the fields of automobile manufacturing and sports protection.

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