A processable high flow low surface fiber reinforced polypropylene composite material and its preparation and use

Abstract

This invention relates to an easily processable, high-flowability, low-surface-float fiber-reinforced polypropylene composite material, its preparation method, and its applications. The easily processable, high-flowability, low-surface-float fiber-reinforced polypropylene composite material mainly comprises long glass fiber reinforced polypropylene (LGF-PP) and ultra-high flowability polypropylene (PP-H) with high-flowability polypropylene as the matrix, and polypropylene containing short fibers. The three types of particles can be used for molding and processing after physical mixing and melt mixing. The preparation method is simple, inexpensive, and effectively improves the problem of fiber floating on the surface of the product.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and more specifically, to an easily processed, highly fluid, low-surface-float fiber-reinforced polypropylene composite material, its preparation method, and its application. Background Technology

[0002] In recent years, with the improvement of people's living standards and environmental awareness, as well as the rapid development of the plastics industry, people have become more and more demanding of plastic products. Thin-walled and lightweight materials have gradually become the development trend of the plastics industry, which puts forward higher requirements for the performance of materials.

[0003] Polypropylene (PP) is a widely available, high-yield, low-cost general-purpose plastic with excellent comprehensive mechanical properties, stable chemical properties, non-toxicity, odorlessness, and easy processing. Among them, long glass fiber reinforced polypropylene composites have become one of the fastest-growing plastics in automotive materials due to their low density and better mechanical properties, heat resistance, weather resistance, creep resistance, and fatigue resistance. They have broad application prospects in the current context of promoting lightweight automobiles.

[0004] However, due to the difference in flowability between glass fiber and resin matrix, fiber floating occurs on the surface of automotive parts made of long glass fiber reinforced polypropylene materials, resulting in an uneven surface and affecting the appearance of the product. Therefore, fiber floating has become a problem that urgently needs to be solved in glass fiber reinforced polypropylene materials. Currently, a great deal of work has been carried out to address this issue.

[0005] Chinese patent CN103265761 A discloses a low-float glass fiber reinforced polypropylene composite and its preparation method. This method grafts polar monomers onto the polypropylene molecular chain during processing, improving the compatibility between polypropylene and glass fiber and mitigating the fiber float phenomenon. Although this method employs common processing techniques, it requires complex raw materials, and the introduction of a large number of small-molecule processing aids can affect the mechanical properties of the material. Furthermore, the selected grafted monomers produce a pungent odor, which is detrimental to the subsequent processing and use of the material.

[0006] Chinese Patent CN 112048124 A discloses a glass fiber reinforced polypropylene material with low surface fiber floating and its preparation method. This method introduces a low molecular weight polar wax and low isotactic polypropylene into the PP matrix. The polar wax can cooperate with a compatibilizer to improve the bonding force between the glass fiber and the resin, promoting the flowability of the glass fiber in the polypropylene, thereby reducing glass fiber exposure. The low isotactic polypropylene has low crystallization efficiency and good flowability, allowing it to preferentially migrate to the polymer surface during injection molding, preventing glass fiber exposure. Chinese Patent CN 111087698 A discloses a long fiber reinforced polypropylene composite material with improved fiber floating and high surface smoothness, and its preparation method. This method introduces ultra-high flowability and self-lubricating functional masterbatch into conventional long glass fiber reinforced polypropylene chips. Utilizing the self-lubricating effect of the lubricant in the masterbatch, the highly flowable functional masterbatch resin preferentially flows to the outside of the melt, coating the material surface, thereby improving the fiber floating on the product surface. While the above two methods can improve the problem of fiber floating to some extent, the use of large amounts of low molecular weight polar wax and lubricant will not only seriously affect the mechanical properties of the material, but also the low molecular weight polar wax and lubricant are prone to migrate to the surface of the material, making the surface of the material white and sticky, affecting the appearance and performance of the product.

[0007] In summary, existing technologies for improving the fiber floating problem in long glass fiber reinforced polypropylene composites mostly require the addition of large amounts of low molecular weight lubricants, polar waxes, and other processing aids. However, the extensive use of lubricants, polar waxes, and other low molecular weight processing aids can degrade the mechanical properties of the material and easily migrate to the surface of the product, causing whitening and stickiness. Currently, there is an urgent need for a simple processing method that can effectively prevent the migration of small amounts of low molecular weight processing aids to the product surface to improve fiber floating. Summary of the Invention

[0008] To address the aforementioned problems in existing technologies, this invention proposes an easily processable, high-flowability, low-surface-fiber-out reinforced polypropylene composite material. Specifically, it relates to an easily processable, high-flowability, low-surface-fiber-out reinforced polypropylene composite material, its preparation method, and its applications. The easily processable, high-flowability, low-surface-fiber-out reinforced polypropylene composite material of this invention comprises an ultra-high-flowability polypropylene component, which easily flows to the surface of the product during molding, thus effectively suppressing fiber exposure and having minimal impact on the mechanical properties of the composite material. Furthermore, this invention also includes short-fiber polypropylene particles, wherein the short fibers can improve the mechanical properties of the material through network connectivity. Simultaneously, the preparation method is simple, low-cost, and effectively solves the problem of fiber floating on the product surface.

[0009] One of the objectives of this invention is to provide an easy-to-process, high-flowability, low-surface-float fiber-reinforced polypropylene composite material, which may be prepared from the following main raw materials: long glass fiber reinforced polypropylene (LGF-PP) with high-flowability polypropylene as the matrix, ultra-high-flowability polypropylene (PP-H), and polypropylene containing short fibers.

[0010] The total weight of the easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material is taken as 100 parts by weight.

[0011] The amount of long glass fiber reinforced polypropylene (LGF-PP) can be 30 to 96 parts by weight (e.g., 30 parts by weight, 31 parts by weight, 32 parts by weight, 33 parts by weight, 34 parts by weight, 35 parts by weight, 40 parts by weight, 45 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 54 parts by weight, 56 parts by weight, 58 parts by weight, 60 parts by weight, 62 parts by weight, 65 parts by weight, 70 parts by weight, 72 parts by weight, 76 parts by weight, 79 parts by weight, 80 parts by weight, 85 parts by weight, 90 parts by weight, or any value between the above values), preferably 30 to 90 parts by weight, more preferably 50 to 79 parts by weight.

[0012] The amount of ultra-high flowability polypropylene (PP-H) used can be 1 to 40 parts by weight (such as 1 part by weight, 2 parts by weight, 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 8 parts by weight, 10 parts by weight, 15 parts by weight, 20 parts by weight, 22 parts by weight, 25 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 34 parts by weight, 36 parts by weight, 40 parts by weight, or any value between the above values); preferably 2 to 30 parts by weight, more preferably 4 to 28 parts by weight;

[0013] The amount of the short-fiber polypropylene can be 3 to 59 parts by weight (e.g., 3 parts by weight, 4 parts by weight, 5 parts by weight, 6 parts by weight, 7 parts by weight, 8 parts by weight, 10 parts by weight, 12 parts by weight, 15 parts by weight, 20 parts by weight, 22 parts by weight, 25 parts by weight, 28 parts by weight, 30 parts by weight, 32 parts by weight, 34 parts by weight, 36 parts by weight, 39 parts by weight, 40 parts by weight, 42 parts by weight, 45 parts by weight, 48 parts by weight, 50 parts by weight, 52 parts by weight, 54 parts by weight, 56 parts by weight, 59 parts by weight, or any value between the above values), preferably 5 to 45 parts by weight, more preferably 7 to 39 parts by weight.

[0014] The total amount of the long glass fiber reinforced polypropylene (LGF-PP), ultra-high flow polypropylene (PP-H), and short fiber polypropylene is 100 parts by weight.

[0015] in,

[0016] The long glass fiber reinforced polypropylene (LGF-PP) may include high-flow polypropylene (PP) and long glass fibers;

[0017] The long glass fiber reinforced polypropylene (LGF-PP) material refers to a product with a high glass fiber retention length, and the particle length of the product can generally be 5 to 25 mm.

[0018] The long glass fiber reinforced polypropylene can be selected from commercially available long glass fiber reinforced polypropylene particles commonly used in the field, or it can be prepared using existing technologies. Specific preparation methods can refer to existing technologies, such as Duan Zhaohua, Chen Xuan. Research on the Development of Impregnation Technology for Long Glass Fiber Reinforced Composite Materials [J]. Plastics Industry, 2008, 36(S1):221-224. For example, a melt impregnation method can be used. Specific preparation steps may include melt extruding the high-flowability polypropylene (PP), impregnating and coating the continuous glass fiber, and then water cooling, traction, and pelletizing to obtain the long glass fiber reinforced polypropylene (LGF-PP). The continuous glass fiber can be selected from alkali-free continuous glass fiber modified with a silane coupling agent, with a fiber diameter of 14–18 μm and a linear density of 2400 tex or 3600 tex.

[0019] The high-flow polypropylene (PP) required for the preparation of LGF-PP may be selected from at least one of homopolymer polypropylene, copolymer polypropylene, and impact copolymer polypropylene; and / or

[0020] The melt index of the high-flow polypropylene (PP) can be 80-100 g / 10 min (230°C, 2.16 kg) (for example, it can be 80 g / 10 min, 85 g / 10 min, 90 g / 10 min, 95 g / 10 min, 100 g / 10 min or any value between the above values).

[0021] Preferably, the length of the long glass fiber can be 5–25 mm (e.g., 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 22 mm, 25 mm or any value between the above), preferably 10–15 mm. The fiber diameter can be 14–18 μm.

[0022] Preferably, based on 100wt% of the total weight of the long glass fiber reinforced polypropylene, the content of the long glass fiber can be 5-80wt% (specifically, such as 5wt%, 5.5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, 12wt%, 15wt%, 17wt%, 19wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, or any value between the above values), for example, preferably 5-60wt%, more preferably 10-40wt%; the content of the high-flowability polypropylene (PP) can be 95-20wt%, preferably 95-40wt%, more preferably 90-60wt%.

[0023] In some specific embodiments of the present invention,

[0024] The ultra-high flowability polypropylene (PP-H) may be selected from at least one of homopolymer polypropylene, copolymer polypropylene, and impact copolymer polypropylene, preferably homopolymer polypropylene; and / or,

[0025] The melt flow index of the ultra-high flowability polypropylene (PP-H) can be 150–5000 g / 10 min (230°C, 2.16 kg) (e.g., 150 g / 10 min, 200 g / 10 min, 250 g / 10 min, 300 g / 10 min, 350 g / 10 min, 400 g / 10 min, 450 g / 10 min, 500 g / 10 min, 550 g / 10 min, 600 g / 10 min, 700 g / 10 min, 750 g / 10 min, 800 g / 10 min, 900 g / 10 min, 1000 g / 10 min, 1100 g / 10 min, 1200 g / 10 min, 1300 g / 10 min, 1500 g / 10 min, 1700 g / 10 min). The values ​​are 2000g / 10min, 2200g / 10min, 2500g / 10min, 2700g / 10min, 3000g / 10min, 3500g / 10min, 4000g / 10min, 4500g / 10min, 4700g / 10min, 5000g / 10min, or any value between the above. Specifically, for example, 450-5000g / 10min (230℃, 2.16kg) is preferred, 450-3000g / 10min (230℃, 2.16kg) is preferred, 1000-5000g / 10min (230℃, 2.16kg) is preferred, and 1500-4500g / 10min (230℃, 2.16kg) is preferred.

[0026] In some specific embodiments of the present invention,

[0027] The weight-average molecular weight of the ultra-high flowability polypropylene (PP-H) can be 50,000 to 200,000 g / mol, preferably 80,000 to 150,000 g / mol.

[0028] In some specific implementations of this application,

[0029] The melt index of the ultra-high flow polypropylene (PP-H) can be more than 2 times, preferably more than 3 times, and more preferably 3 to 40 times that of the high flow polypropylene PP used to prepare long glass fiber reinforced polypropylene (LGF-PP) (for example, it can be 3 times, 4 times, 5 times, 6 times, 7 times, 8 times, 9 times, 10 times, 11 times, 12 times, 15 times, 17 times, 20 times, 25 times, 27 times, 30 times, 32 times, 35 times, 38 times, 40 times or any value between the above values).

[0030] In some specific embodiments of the present invention,

[0031] The particle length of the product containing short fiber polypropylene can be 1-5 mm, preferably 3-5 mm.

[0032] The short-fiber-containing polypropylene may include polypropylene resin and short fibers;

[0033] The preparation method of the short-fiber polypropylene may include the following steps: first, physically mixing polypropylene with short glass fibers, then melt-extruding, followed by water cooling and pelletizing. The melt extrusion can be performed using commonly used equipment in the field, such as a single-screw extruder. Specifically, a single-screw extruder can be used for melt extrusion at 190–220°C.

[0034] The polypropylene resin used to prepare the short-fiber polypropylene may be selected from at least one of homopolymer polypropylene, copolymer polypropylene, and impact copolymer polypropylene, preferably copolymer polypropylene; and / or,

[0035] The melt index of the polypropylene resin used to prepare the short-fiber polypropylene can be 0.1 to 65 g / 10 min (230°C, 2.16 kg) (e.g., 0.1 g / 10 min, 0.5 g / 10 min, 1 g / 10 min, 1.5 g / 10 min, 2 g / 10 min, 3 g / 10 min, 5 g / 10 min, 10 g / 10 min, 15 g / 10 min, 20 g / 10 min, 25 g / 10 min, 30 g / 10 min, etc.). The values ​​are 10 min, 35 g / 10 min, 40 g / 10 min, 45 g / 10 min, 50 g / 10 min, 55 g / 10 min, 59 g / 10 min, 60 g / 10 min, 62 g / 10 min, 65 g / 10 min, or any value between the above. For example, 2 to 60 g / 10 min (230°C, 2.16 kg) is preferred, and 3 to 30 g / 10 min (230°C, 2.16 kg) is even more preferred.

[0036] Preferably, the short fiber is made of glass fiber; the length of the short fiber can be 1-5 mm, preferably 3-5 mm; the fiber diameter of the short fiber can be 10-18 μm.

[0037] Preferably, based on the total weight of the short-fiber polypropylene (100%), the content of the short fibers can be 5-60 wt% (specifically, such as 5 wt%, 5.5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 12 wt%, 15 wt%, 17 wt%, 19 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or any value between the above values), more preferably 10-40 wt%; the content of the polypropylene resin can be 95-40 wt%, more preferably 90-60 wt%.

[0038] A second objective of this invention is to provide a method for preparing the aforementioned easily processed, highly fluid, low-surface-float fiber-reinforced polypropylene composite material, which may include the following steps:

[0039] The long glass fiber reinforced polypropylene (LGF-PP), ultra-high flow polypropylene (PP-H), and short fiber polypropylene, among other components, are melt-blended according to the specified amounts. Preferably, the melt-blending temperature range is 190–250°C; the specific temperature can be adjusted according to actual conditions.

[0040] Specifically, the method may include the following steps: first, physically mixing long glass fiber reinforced polypropylene (LGF-PP) and ultra-high flow polypropylene (PP-H) with high flow polypropylene as the matrix and components including short fiber polypropylene (specifically, a small solid material mixer, high-speed mixer or other common equipment in the art can be used); then, the material is melt-molded to prepare the composite material (specifically, a screw extruder and injection molding machine or other common equipment in the art can be used). In specific use, it is not necessary to use a twin-screw extruder; the material can be directly injection molded into products after physical mixing.

[0041] The third objective of this invention is to provide a readily processable, highly fluid, low-surface-float fiber-reinforced polypropylene composite material prepared by the preparation method described in the second objective of this invention.

[0042] The fourth objective of this invention is to provide applications of the easily processed, highly fluid, low-surface-float fiber-reinforced polypropylene composite material described in the first objective of this invention, or the polypropylene composite material prepared by the method described in the second objective of this invention, preferably in the fields of automobiles, home appliances, and textiles.

[0043] In practice,

[0044] The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material of the present invention may contain the following blended components: long glass fiber reinforced polypropylene (LGF-PP) with high-flowability polypropylene as the matrix, ultra-high-flowability polypropylene (PP-H), and polypropylene containing short fibers.

[0045] In this embodiment, by weight parts, 1) the amount of long glass fiber reinforced polypropylene (LGF-PP) based on high-flow polypropylene is 30 to 96 parts by weight, preferably 30 to 90 parts by weight; 2) the amount of ultra-high flow polypropylene (PP-H) is 1 to 40 parts by weight, preferably 2 to 30 parts by weight; and 3) the amount of polypropylene containing short fibers is 3 to 59 parts by weight, preferably 5 to 45 parts by weight.

[0046] The easily processed, high-flowability, low-surface-fiber-reinforced polypropylene composite material of this invention mainly consists of long glass fiber reinforced polypropylene particles (LGF-PP) and ultra-high-flowability polypropylene particles (PP-H) with high-flowability polypropylene as the matrix, and polypropylene particles containing short fibers. These three types of particles can be used for product molding after physical mixing and melt mixing. LGF-PP has a large component content, and the polypropylene itself has high flowability, which plays a certain role in preventing glass fiber exposure; PP-H has even higher flowability, which better suppresses glass fiber exposure; the polypropylene particles containing short fibers act as a network connector in the material, which can improve the material's mechanical properties and maintain good surface properties. The preparation method of the polypropylene composite material described in this application has a simple manufacturing process, low preparation cost, and can effectively improve the problem of fiber floating on the surface of the product.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] 1. Firstly, LGF-PP has a large component content, and the polypropylene itself has high fluidity, which plays a role in preventing glass fiber exposure. Secondly, PP-H has even higher fluidity; a small amount of PP-H more easily migrates to the surface of the product, thus better suppressing glass fiber exposure. The polypropylene particles containing short fibers act as a network in the material, improving both its mechanical properties and maintaining good surface properties.

[0049] 2. PP-H with higher fluidity still has a higher molecular weight, which can maintain the mechanical properties of the material well and will not cause other problems to the surface quality of the material.

[0050] 3. LGF-PP, PP-H, and polypropylene particles containing short fibers can be directly used for product molding through simple physical mixing. This makes it easier for PP-H to migrate to the surface of the product during injection molding, improving the fiber floating problem. On the other hand, this application simplifies the processing steps and reduces production costs. Detailed Implementation

[0051] 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.

[0052] 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.

[0053] Source of raw materials

[0054] YPJ3100H, homopolymer polypropylene, melt flow rate (MFR) of 100g / 10min (230℃ / 2.16kg), Sinopec Yangzi Petrochemical Co., Ltd.

[0055] Grade K7780, copolymer polypropylene, melt flow rate (MFR) of 80 g / 10 min (230℃ / 2.16 kg), Yanshan Petrochemical;

[0056] Ultra-high flowability polypropylene particles (PP-H): Grade MH7900, homopolymer polypropylene, MFR of 150g / 10min (230℃ / 2.16kg), weight average molecular weight of 80,000~150,000g / mol, LG Chem, South Korea;

[0057] Ultra-high flow polypropylene particles (PP-H): MFR 450g / 10min (230℃ / 2.16kg), grade PPH-Y450, homopolymer polypropylene, Shijiazhuang Refining & Chemical Co., Ltd.

[0058] Ultra-high flow polypropylene particles (PP-H): MFR 1500g / 10min (230℃ / 2.16kg), 6936G2, homopolymer polypropylene, ExxonMobil, USA;

[0059] Ultra-high flow polypropylene particles (PP-H): MFR of 2500g / 10min (230℃ / 2.16kg), PPH-Y2500, Shijiazhuang Refining & Chemical Co., Ltd.

[0060] LGF: Grade SE4805-2400, diameter 17μm, Owens Corning, USA.

[0061] Short fiberglass:

[0062] GF: ECS13-4.5-508A, typical fiber diameter is 13μm, typical chopped length is 4.5mm, Jushi Group Co., Ltd.;

[0063] GF: ECS13-03-552B, typical fiber diameter is 13μm, typical chopped length is 3mm, Jushi Group Co., Ltd.;

[0064] GF: 435N, typical fiber diameter is 13μm, typical chopped length is 1mm, Taishan Fiberglass.

[0065] Long glass fiber reinforced polypropylene (LGF-PP) is prepared by melt impregnation. The specific preparation method may include the following steps: first, PP material is placed into the feed port of the twin-screw extruder of the long fiber equipment for melt extrusion; then, continuous glass fibers are introduced into the impregnation die through the glass fiber frame of the long fiber equipment for impregnation and coating; and then, after water cooling, traction, and pelletizing, the long glass fiber reinforced polypropylene (LGF-PP) can be obtained.

[0066] The short fiber polypropylene particles are prepared by melt impregnation. The specific preparation method may include the following steps: first, the polypropylene and short glass fibers are physically mixed, then melt-extruded at 200°C using a single screw extruder, and then cooled with water and pelletized.

[0067] PP with a melt flow index of 59 g / 10 min, HP544T, from Basel, Thailand;

[0068] PP with a melt flow index of 3 g / 10 min, T30S, Qilu Petrochemical;

[0069] PP with a melt flow index of 30 g / 10 min, M3000RH, Sinopec Shanghai Petrochemical Co., Ltd.

[0070] Unless otherwise specified, the raw materials used in the examples and comparative examples are all disclosed in the prior art, such as those that can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0071] Example 1

[0072] Long glass fiber reinforced polypropylene particles (LGF-PP) with a glass fiber content of 30 wt% and a fiber length of 10 mm, prepared from PP (grade YPJ3100H) with a melt index of 100 g / 10 min, were physically mixed with 4 parts by weight of ultra-high flow polypropylene particles (PP-H) with a melt index of 450 g / 10 min, and 7 parts by weight of short fiber polypropylene particles containing glass fiber content of 60 wt% and a fiber length of 4.5 mm, prepared from PP with a melt index of 59 g / 10 min. The mixed particles were then injection molded at 240℃ using an injection molding machine, with the injection pressure controlled at 40 MPa, the injection time at 8 s, and the mold temperature at 25℃. The surface fiber shedding of the samples was observed, and the results are listed in Appendix 1. The tensile strength and flexural strength of the materials were tested according to GB / T 1040-92 and GB / T 9341-2008, and the results are listed in Appendix 2.

[0073] Example 2

[0074] 63 parts by weight of long glass fiber reinforced polypropylene particles (LGF-PP) with a glass fiber content of 40 wt% and a fiber length of 15 mm, prepared from PP with a melt index of 100 g / 10 min, 24 parts by weight of ultra-high flowability polypropylene particles (PP-H) with a melt index of 1500 g / 10 min, and 13 parts by weight of short fiber polypropylene particles containing glass fiber with a glass fiber content of 40 wt% and a fiber length of 3 mm, prepared from PP with a melt index of 3 g / 10 min, were physically mixed. The mixed particles were then injection molded at 240℃ using an injection molding machine, with the injection pressure controlled at 40 MPa, the injection time at 8 s, and the mold temperature at 25℃. The surface fiber shedding of the samples was observed, and the results are listed in Appendix 1. The mechanical properties of the samples were measured, and the results are listed in Appendix 2.

[0075] Example 3

[0076] Long glass fiber reinforced polypropylene particles (LGF-PP) with a glass fiber content of 10 wt% and a fiber length of 10 mm, prepared from PP with a melt index of 80 g / 10 min, 30 parts by weight of ultra-high flowability polypropylene particles (PP-H) with a melt index of 2500 g / 10 min, and 39 parts by weight of polypropylene particles containing short fibers with a glass fiber content of 5 wt% and a fiber length of 1 mm, prepared from PP with a melt index of 30 g / 10 min, were physically mixed. The mixed particles were then injection molded at 240℃ using an injection molding machine, with the injection pressure controlled at 40 MPa, the injection time at 8 s, and the mold temperature at 25℃. The surface fiber shedding of the samples was observed, and the results are listed in Appendix 1. The mechanical properties of the samples were measured, and the results are listed in Appendix 2.

[0077] Comparative Example 1

[0078] Long glass fiber reinforced polypropylene (LGF-PP) particles, prepared from high-flow polypropylene with a glass fiber content of 40 wt% and a fiber length of 15 mm, made from PP with a melt index of 100 g / 10 min, were directly injection molded using an injection molding machine. The injection pressure was controlled at 40 MPa, the injection time at 8 s, and the mold temperature at 25℃. The surface fiber floating condition of the samples was observed, and the results are listed in Appendix 1. The mechanical properties of the samples were measured, and the results are listed in Appendix 2.

[0079] Comparative Example 2

[0080] 96 parts by weight of long glass fiber reinforced polypropylene particles (LGF-PP) prepared from PP with a melt index of 100 g / 10 min and a glass fiber content of 40 wt% and a fiber length of 15 mm were physically mixed with 4 parts by weight of ultra-high flowability polypropylene particles (PP-H) with a melt index of 150 g / 10 min. The mixed particles were then injection molded at 240°C using an injection molding machine, with the injection pressure controlled at 40 MPa, the injection time at 8 s, and the mold temperature at 25°C. The surface fiber floating condition of the samples was observed, and the results are listed in Appendix 1. The mechanical properties of the samples were measured, and the results are listed in Appendix 2.

[0081] Comparative Example 3

[0082] 96 parts by weight of long glass fiber reinforced polypropylene particles (LGF-PP) prepared from high-flow polypropylene with a glass fiber content of 40 wt% and a fiber length of 15 mm, using PP with a melt index of 150 g / 10 min, and 4 parts by weight of ultra-high flow polypropylene particles (PP-H) with a melt index of 150 g / 10 min were physically mixed. The mixed particles were then injection molded at 240℃ using an injection molding machine, with the injection pressure controlled at 40 MPa, injection time at 8 s, and mold temperature at 25℃. The surface fiber shedding of the samples was observed, and the results are listed in Appendix 1. The mechanical properties of the samples were measured, and the results are listed in Appendix 2.

[0083] The evaluation of fiber floating grade is mainly based on injection molding the material into a rectangular test sample of 350mm*100mm*3mm under a specific injection molding process. The fiber floating state on the sample surface is observed by the naked eye for evaluation. It is mainly divided into 1 to 4 grades (the test method can be found in the reference: Shen Xuqu, Chen Ruibin, He Zihao. Research on improvement of fiber floating problem of glass fiber reinforced polypropylene [J]. Guangdong Chemical Industry, 2021, 48(20):3.). Grade 1: smooth surface, no fiber floating; Grade 2: smooth surface, slight fiber floating; Grade 3: obvious fiber floating; Grade 4: rough surface, serious fiber floating. The test results are shown in Table 1 below.

[0084] Table 1:

[0085] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Level 2 Level 1 Level 1 Level 4 Level 3 Level 3

[0086] Table 2:

[0087]

[0088] Table 1 shows the evaluation of surface fiber floating conditions for Examples 1, 2, and 3, which are easy-to-process, high-flowability, low-surface-fiber-floating long glass fiber reinforced polypropylene composites prepared according to the method provided by the present invention. Comparative Example 1 in Table 1 shows the evaluation of surface fiber floating conditions for products directly injection molded from long glass fiber reinforced polypropylene composites prepared from high-flowability polypropylene. Comparative Example 2 shows the evaluation of surface fiber floating conditions for products prepared by the method described, using 96 parts of long glass fiber reinforced polypropylene particles (LGF-PP) prepared from high-flowability polypropylene and 4 parts of ultra-high-flowability polypropylene particles (PP-H). Comparative Example 3 shows the evaluation of surface fiber floating conditions for products prepared by the method described, using polypropylene with the same melt index.

[0089] As shown in Table 1, with the increase of ultra-high flowability polypropylene particles (PP-H), the surface quality of the product improves, and the fiber floating phenomenon is significantly reduced, which can be controlled within level 2. Furthermore, the melt index of the high flowability polypropylene used to prepare long glass fiber reinforced polypropylene composite particles (LGF-PP) is significantly lower than that of the other ultra-high flowability polypropylene particle (PP-H), which is more beneficial for reducing fiber floating on the material surface. This is because during the die-cutting process, the more flowable polypropylene preferentially migrates to the surface of the product, coating the surface layer and thus reducing glass fiber exposure.

[0090] As can be clearly seen from Table 2, the mechanical properties of the samples prepared by this method do not show a significant decrease, and the addition of a small amount of short fibers slightly increases the mechanical properties of the products.

Claims

1. A processable, high-flowability, low-surface-float fiber-reinforced polypropylene composite material, characterized in that... It includes long glass fiber reinforced polypropylene LGF-PP, ultra-high flow polypropylene PP-H, and polypropylene containing short fibers; Based on 100 parts by weight of the total weight of the easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material, the amount of long glass fiber reinforced polypropylene LGF-PP is 30-96 parts by weight; the amount of ultra-high flowability polypropylene PP-H is 1-40 parts by weight; and the amount of short fiber-containing polypropylene is 3-59 parts by weight. The long glass fiber reinforced polypropylene LGF-PP comprises high-flow polypropylene PP and long glass fibers; the high-flow polypropylene PP has a melt index of 80~100g / 10min under the conditions of temperature 230℃ and load 2.16kg; the long glass fibers have a length of 6~25mm; The ultra-high flowability polypropylene PP-H has a melt index of 150~5000g / 10min under the conditions of temperature 230℃ and load 2.16kg; The melt index of the ultra-high flow polypropylene PP-H is more than twice that of the high flow polypropylene PP used to prepare long glass fiber reinforced polypropylene LGF-PP. Based on a total weight of 100wt% for the long glass fiber reinforced polypropylene LGF-PP, the content of the long glass fiber is between 5% and 80wt%. The polypropylene containing short fibers has a melt index of 2~60g / 10min under the conditions of temperature 230℃ and load 2.16kg. The short-fiber polypropylene comprises polypropylene resin and short fibers; the short fibers have a length of 1~5mm. Based on a total weight of 100 wt% of the polypropylene containing short fibers, the content of the short fibers is 5 to 60 wt%.

2. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1, characterized in that: Based on 100 parts by weight of the easily processed, highly fluid, low-surface-float fiber-reinforced polypropylene composite material, The amount of long glass fiber reinforced polypropylene LGF-PP is 30-90 parts by weight; the amount of ultra-high flowability polypropylene PP-H is 2-30 parts by weight; and the amount of short fiber-containing polypropylene is 5-45 parts by weight.

3. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The high-flowability polypropylene (PP) is selected from at least one of homopolymer polypropylene and copolymer polypropylene.

4. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The high-flow polypropylene (PP) is an impact-resistant copolymer polypropylene.

5. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1, characterized in that: The length of the long glass fiber is 10~15mm.

6. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1, characterized in that: Based on a total weight of 100wt% for the long glass fiber reinforced polypropylene LGF-PP, the content of the long glass fiber is 5~60wt%.

7. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 6, characterized in that: Based on a total weight of 100wt% for the long glass fiber reinforced polypropylene LGF-PP, the content of the long glass fiber is 10~40wt%.

8. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The ultra-high flowability polypropylene PP-H has a melt index of 450~5000g / 10min under the conditions of temperature 230℃ and load 2.16kg.

9. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 8, characterized in that: The ultra-high flowability polypropylene PP-H has a melt index of 1000~5000g / 10min under the conditions of temperature 230℃ and load 2.16kg.

10. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 9, characterized in that: The ultra-high flowability polypropylene PP-H has a melt index of 1500~4500g / 10min under the conditions of temperature 230℃ and load 2.16kg.

11. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The ultra-high flowability polypropylene PP-H is selected from at least one of homopolymer polypropylene and copolymer polypropylene.

12. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 11, characterized in that: The ultra-high flowability polypropylene PP-H is a homopolymer polypropylene.

13. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The ultra-high flowability polypropylene PP-H is an impact-resistant copolymer polypropylene.

14. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The melt index of the ultra-high flow polypropylene PP-H is more than three times that of the high flow polypropylene PP used to prepare long glass fiber reinforced polypropylene LGF-PP.

15. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 14, characterized in that: The melt index of the ultra-high flow polypropylene PP-H is 3 to 40 times that of the high flow polypropylene PP used to prepare long glass fiber reinforced polypropylene LGF-PP.

16. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The short-fiber polypropylene contains polypropylene resin selected from at least one of homopolymer polypropylene and copolymer polypropylene.

17. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The short-fiber polypropylene contains polypropylene resin that is an impact copolymer polypropylene.

18. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1 or 2, characterized in that: The polypropylene containing short fibers has a melt index of 3~30g / 10min under conditions of 230℃ and 2.16kg load.

19. The easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 1, characterized in that: Based on a total weight of 100wt% of the polypropylene containing short fibers, the content of the short fibers is 10~40wt%.

20. The method for preparing the easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to any one of claims 1 to 19, characterized in that... Includes the following steps: The composite material is prepared by first physically mixing long glass fiber reinforced polypropylene LGF-PP, ultra-high flowability polypropylene PP-H, and components including short fiber polypropylene, and then by melt blending of the materials.

21. The method for preparing the easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to claim 20, characterized in that: The temperature range for melt blending is 190~250℃.

22. An easily processed, highly fluid, low-surface-float fiber-reinforced polypropylene composite material prepared by the preparation method according to claim 20 or 21.

23. The application of the easily processed, high-flowability, low-surface-float fiber-reinforced polypropylene composite material according to any one of claims 1 to 19, or the polypropylene composite material prepared by the method according to claim 20, in the automotive, home appliance, or textile fields.

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