WO2022183903A1 - 一种连续纤维增强热塑性复合物微发泡制品及其成型方法和装置 - Google Patents

一种连续纤维增强热塑性复合物微发泡制品及其成型方法和装置 Download PDF

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WO2022183903A1
WO2022183903A1 PCT/CN2022/076286 CN2022076286W WO2022183903A1 WO 2022183903 A1 WO2022183903 A1 WO 2022183903A1 CN 2022076286 W CN2022076286 W CN 2022076286W WO 2022183903 A1 WO2022183903 A1 WO 2022183903A1
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mold
reinforced thermoplastic
product
supercritical fluid
degrees
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PCT/CN2022/076286
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English (en)
French (fr)
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周应国
孙弘龙
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江苏科技大学
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Publication of WO2022183903A1 publication Critical patent/WO2022183903A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
    • B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/40—Shaping or impregnating by compression not applied
    • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
    • B29C70/46—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs
    • B29C70/48—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using matched moulds, e.g. for deforming sheet moulding compounds [SMC] or prepregs and impregnating the reinforcements in the closed mould, e.g. resin transfer moulding [RTM], e.g. by vacuum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
    • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
    • B29C70/28—Shaping operations therefor
    • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing

Definitions

  • the invention relates to a composite material and its processing and molding, in particular to a molding method of a continuous fiber-reinforced thermoplastic composite micro-foamed product.
  • micro- and nano-scale cells can also impart some excellent properties to polymer materials, and are now widely used in packaging. , construction, automobiles, aerospace, sports equipment and many other fields, but they are often limited due to insufficient performance, especially mechanical properties.
  • Using fibers as reinforcements is a way to solve the insufficient mechanical properties of polymer materials.
  • fiber reinforced polymer composites have become a vigorous development in aerospace, military and other fields due to their outstanding advantages such as high mechanical properties, low density, corrosion resistance, fatigue resistance, recyclability, weldability, environmental friendliness, and short molding cycle. Key material for a wide range of applications. Among them, compared with thermoset composites, continuous fiber-reinforced thermoplastic composites (FRTP) have the advantages of short molding cycle, good impact resistance, and easy repair and recycling, showing a strong development momentum.
  • FRTP continuous fiber-reinforced thermoplastic composites
  • FRTP with micro- and nano-cellular features will have both the advantages of traditional FRTP and micro-cellular foamed products.
  • the existing fiber-reinforced thermoplastic microporous products are often processed by the following two methods: (1) The foaming process is completed separately, that is, the foaming process and the molding process of the material are completed in steps, and it is often foamed. Products and fiber reinforced materials are prepared in steps and then bonded or composited to form a "sandwich" structure. The layered size of such products is often large, and this macroscopic layering results in poor material consistency.
  • thermoplastic micro-foamed products As mentioned above, the materials contained in this type of product are not single, and its performance and performance are basically the sum of two types of materials; (2) Another type of fiber-reinforced thermoplastic micro-foamed products is online during the molding process of the product. Foamed, but most of the fibers it contains are short fibers or long fibers. At this time, the orientation of the fibers in the thermoplastic polymer is inconsistent, which makes it common to use short fibers or long fibers to strengthen the fibers in thermoplastic microfoamed products. Performance is not obvious.
  • One of the purposes of the present invention is to provide a continuous fiber reinforced thermoplastic composite micro-foamed product with excellent comprehensive properties;
  • the second purpose of the present invention is to provide a continuous fiber reinforced thermoplastic composite micro-foamed product molding.
  • the method can prepare a foamed product with excellent comprehensive properties;
  • the third purpose of the present invention is to provide a molding device for a continuous fiber-reinforced thermoplastic composite micro-foamed product.
  • the present invention provides a continuous fiber reinforced thermoplastic composite micro-foaming product, which takes thermoplastic polymer as matrix and continuous fiber as reinforcing phase; the micro-foaming product has a single-oriented microporous structure, and the continuous fiber is arranged in parallel.
  • the product is composed of continuous fibers and polymers, and the foamed product has a special microporous structure oriented in a single direction. layer structure.
  • the direction of cell orientation is along the thickness direction of the product.
  • the continuous fibers in the micro-foamed product are arranged in parallel, and the content of the continuous fibers is 10-60 wt%.
  • the present invention also provides a method for forming a continuous fiber-reinforced thermoplastic composite micro-foamed product, comprising the following steps:
  • thermoplastic polymer thin-layer prepreg (1) compounding the widened continuous fiber and thermoplastic polymer to form a fiber-reinforced thermoplastic polymer thin-layer prepreg;
  • the continuous fibers used can be one or more of carbon fibers, glass fibers, basalt fibers, aramid fibers, ultra-high molecular weight polyethylene fibers and other fibers that are spun from polymers. ; Its synchronously widened and composite fibers can be one or more bundles; the tow of each bundle of fibers can be between 1K and 128K.
  • the thermoplastic polymer used for compounding can be one or more of PEEK, PPS, PA, PC, PEN, PET, PBT, PP, and can be supplied in powder or film form.
  • the thickness of the fiber-reinforced thermoplastic polymer thin-layer prepreg tape is 10 ⁇ m ⁇ 100 ⁇ m, and the fiber content is 10 ⁇ 80 wt %.
  • step (2) the laying of the fiber prepreg tape is carried out under a certain pre-tightening force, preferably, the pre-tightening force is 0.01-0.05 MPa; the laying angle can be any between 0 and 90 degrees. An angle, the laying angle between the different layers can be the same or different. Among them, a pre-tightening force of 0.01-0.05 MPa can ensure the smooth laying of the pre-preg tape, and if the pre-tightening force is too large, there may always be tensile stress in the pre-preg tape.
  • the melting point is not higher than that of the prepreg, and the difference between the two melting points is within 10 degrees; that is, the difference between the melting point of the polymer film or sheet laid between adjacent prepreg tapes and the melting point of the prepreg is less than or equal to 10°C.
  • the supercritical fluid injected in the above step (3) can be nitrogen, carbon dioxide, or a mixed gas thereof.
  • the heating and pressure treatment includes at least three stages, and the temperature increase in each stage is preferably 1/5 to 1/3 of the difference between the peak heating temperature of the prepreg and the room temperature , the three stages of pressure are between 1-2MPA, 4-6MPA, and 9-12MPA respectively.
  • the time of each stage can be determined according to the thickness of the final product, which can be between 5 and 60 minutes.
  • the heating treatment includes heating from room temperature to the peak heating temperature of the prepreg in stages, and the pressure treatment includes at least three stages, and the three stages are respectively set between 1-2MPA, 4-6MPA, and 9-12MPA, and each The control time of each stage is 5-60min.
  • T Heating T Measure ⁇ 10°C
  • T Measure is the corresponding temperature value when the equilibrium torque value of the thermoplastic polymer is 8-12 N*m under the rheological test conditions and the rotational speed of 5 rpm.
  • the heating temperature peak T Heating is determined based on the rheological experiment of the polymer matrix in the prepreg, and the polymer material in the prepreg is put into the torque rheometer to test at different heating temperatures, At a low speed of 5rpm, the equilibrium torque value is within the range of 10 degrees above and below the temperature value at 8-12N*m; specifically, the polymer material in the prepreg can be put into the torque rheometer to polymerize It is tested within the range of 50 degrees up and down near the melting point of the material, and the balance torque value is within the range of 10 degrees above and below the temperature value at 8-12N*m at a low speed of 5rpm.
  • This torque value means that the material at this time can not only melt, but also maintain a certain viscosity at a small rotation speed, that is, a low shear rate. If the torque value is too large, the temperature value is too low, and the materials in the later stage are not well integrated with each other. If the torque value is small, the temperature value is too high, and the material in the later stage is difficult to maintain the original arrangement of fibers under pressure. state.
  • the supercritical fluid is injected in the range of 30-50 degrees lower than the previous heating temperature, the pressure must be above the supercritical state of the supercritical fluid, and the injection is constant The speed should not be too fast or too slow. Generally, the whole injection process is completed within 3 to 5 minutes.
  • the material after injection of the supercritical fluid is stabilized to a temperature that is 20 ⁇ 20% lower than the peak T of the prepreg heating temperature. The temperature range after 40 degrees, and keep it for 5 to 20 minutes to make the temperature distribution of the preform uniform;
  • step (3) a preheated supercritical fluid is injected into the mold, the preheating temperature is 30-50°C lower than the prepreg heating temperature peak T heating temperature, and the pressure is kept above the supercritical state; After the critical fluid, the temperature of the preform is stabilized in the range of 20-40° C. lower than the prepreg heating temperature peak T heating temperature, and maintained for 5-20 minutes.
  • the pressure can be maintained at 10-20 MPa; the pressure value corresponding to the specific gas medium in the supercritical state can be easily realized by the prior art, and details are not repeated here.
  • step (4) the cooling process of the preform is carried out in 2-5 stages, the cooling range of each stage is controlled at 5-10°C, and the temperature holding time of each stage is 5-40min.
  • the supercritical fluid discharge direction and the mold opening direction can be the same or different (for example, the two directions are perpendicular to each other); the supercritical fluid discharge speed is much higher than the mold opening speed.
  • the prepreg formed by the prepreg tape is heated and pre-pressed step by step under vacuuming conditions to ensure that the fibers in the prepreg maintain their precise configuration and arrangement, and the final temperature reached is higher than the pre-preg.
  • the melt temperature of the impregnated matrix resin is evacuated.
  • the pre-heated supercritical fluid is introduced after the temperature is lowered, and after a period of time, the temperature is lowered again and kept for a certain period of time; the cooling range of each time is controlled at 5 ⁇ 10 degrees, the cooling can be carried out in 2 to 5 stages, depending on the size of the product, the holding time is between 5 and 40 minutes.
  • the density of the product obtained by the above-mentioned molding method provided by the present invention is between 0.01 and 1 times that of the same fiber-reinforced unfoamed product; fibers and cells are layered on the micron scale; the distribution of fibers in the final product and its distribution in the preform The distribution can be kept consistent.
  • the present invention also provides a molding device for continuous fiber-reinforced thermoplastic composite micro-foaming products, which comprises a controller, a molding die, a pressure device and a supercritical fluid injection device, the controller is connected to the molding die, the supercritical fluid injection device and the The pressure device is connected;
  • the forming mold includes a matching upper mold and a lower mold, an inner mold core arranged above the molded product, the inner mold core is connected with the pressure device, and the pressure device drives the inner mold core to move between the upper and lower molds;
  • the said The upper mold is provided with a first gas channel
  • the inner mold core is provided with a second gas channel
  • the first gas channel is connected with the supercritical fluid injection device. That is, the supercritical fluid is passed into the mold through the first gas channel, and then into the molded product through the second gas channel; when it is discharged, it is discharged through the second gas channel and the first gas channel.
  • the shaped article is placed in the lower mold, and the upper and lower molds are installed to form a closed space; the controller controls the heating and cooling of the mold, the opening and closing of gas passages, and the operation of the pressure device and the supercritical injection device.
  • a high-pressure exhaust valve is installed on the gas channel, the high-pressure exhaust valve is connected with the controller, and the controller is connected with the high-pressure exhaust valve, thereby realizing the opening and closing of the gas channel.
  • the second gas channel is perpendicular to the shaped product, and the obtained cell orientation direction is the thickness direction of the product. That is, the continuous fibers in the product are in a horizontal direction, and the direction of the micropores in the product is perpendicular to the continuous fibers.
  • the inner core moves up and down in the space between the upper and lower molds, and the stroke of the up and down movement is determined according to the degree of foaming.
  • the stroke is 2 to 5 times the thickness of the preform.
  • the foaming ratio of the preform can be achieved by 2 to 5 times only by the movement of the inner core.
  • the foaming ratio is required to be higher, it can be achieved by opening the upper mold.
  • the forming mold of the present invention includes upper and lower half molds, wherein at least half of the molds have a double-layer structure, and the two layers can perform relative movement under the action of force, and the inner layer of the mold has a mechanism leading to the outer layer.
  • the outer layer is equipped with a high-pressure exhaust valve, and there are tiny pores that can communicate with each other between the inner and outer walls. The tiny pores are evenly distributed, and the exhaust direction is consistent; after the upper and lower molds are closed, the high-pressure exhaust valve can be closed. After the supercritical fluid is introduced, the gas will not leak when the pressure reaches above the working pressure (the pressure of the gas mentioned above), and the gas in the inner layer can be quickly discharged after the high-pressure exhaust valve is opened.
  • the device has the ability to achieve a supercritical fluid state under pressure and temperature control of one or both of nitrogen or carbon dioxide, and can inject at a constant flow rate or pressure at a set temperature. into the above mold.
  • thermoplastic resins is generally higher than that of thermosetting resins, which may affect the infiltration between resins and fibers; foaming;
  • the interface between the resin and the fiber may be damaged, so that the fiber is damaged under the protection of the lack of resin; the foaming process is difficult to control, and the uneven foaming leads to poor material properties and insufficient uniformity; foaming affects the continuous fiber. distribution, making the final product poorer in performance or less consistent, etc.
  • the present invention provides a molding method and a molding device for a continuous fiber-reinforced thermoplastic composite micro-foamed product. Through the entire process route and conditions, a processing method for obtaining a FRTP product with uniform micropores and fiber distribution, the mechanical properties of which are significantly higher than Ordinary FRTP products.
  • the basic principle of the present invention is that the fibers in the prepreg tape obtained by compounding the thermoplastic polymer after widening the fibers are unidirectionally consistent, and the fiber layers in the laminate obtained by laminating the prepreg tape or compounding with the polymer film are uniformly distributed. , and then realize controllable foaming under limited conditions.
  • the foaming area is concentrated in the interlayer part of the prepreg tape, so that the interface between the resin and the fiber is not damaged.
  • the polymer can be fully absorbed into the supercritical fluid and discharged in one direction as needed.
  • the foaming is uniform and oriented along the specified discharge direction, and the final obtained cells are along the gas.
  • the consistency of the orientation of the pressure relief direction is good, and at the same time, the distribution of continuous fibers is hardly damaged and affected by the growth of cells, and the arrangement of fibers still maintains the state in the preform.
  • the interlayer delamination between the fibers and the micropores of the product is on the micrometer scale, and macroscopically, it is a material that integrates fibers and micropores, so its comprehensive performance shows a certain scale multiplication effect.
  • the continuous fiber reinforced foamed product manufactured by the invention effectively solves the problem of continuous fiber distribution in the foamed product, the fiber damage rate is low, the lamination and foaming are completed in the same mold, the production efficiency is high, and the foam of the product is high. It has fine pores and excellent mechanical properties, and can be directly applied on a large scale.
  • the continuous fiber reinforced thermoplastic polymer microfoamed product prepared by the invention has the following characteristics: the density of the product is between 0.01 and 1 times that of the ordinary fiber reinforced product; the fiber layer and the cell layer of the product have microscopic layering ; The distribution of fibers in the final product and its distribution in the preform can be kept consistent; the density of micropores in the cell layer is above 10 6 cells/cm 3 .
  • the invention effectively solves the problem of continuous fiber distribution inside the foamed product.
  • the existence of cells reduces the density of the product and improves the impact buffering performance. It has the advantages of thermal insulation of foamed products , sound insulation and other effects, at the same time, the process and its products also have the following advantages: (1) Because the foaming process is carried out after the matrix is melted, the damage to the fibers is avoided to a certain extent; (2) Because the foaming process is In a restricted state, foaming has little effect on the distribution of fibers, the distribution of fibers is relatively uniform, and the consistency is good; (3) Using thermoplastic resin as the matrix and supercritical fluid as the foaming medium, the whole process is green and environmentally friendly , the whole process is pollution-free, and the product has strong recoverability; (4) the cells of the product are small and dense, and the mechanical properties are well maintained; (5) the lamination process and the foaming process of the product are completed in the same mold, and its production process It is continuous, so the entire production process can be applied
  • Fig. 1 is a schematic diagram of the main molding steps of the continuous fiber-reinforced thermoplastic composite micro-foamed product of the present invention.
  • Figure 2 is a schematic view of the structure of the molding die of the present invention.
  • FIG. 3 is a schematic diagram of the supercritical fluid injection and control device of the present invention.
  • FIG. 4 is a flow chart of the control principle of the molding device of the present invention.
  • Figure 5 is a schematic view of the cross-sectional structure of the product made by the present invention.
  • Figure 6 is a scanning electron microscope view of the cross-sectional structure of the product made by the present invention.
  • a method for forming a continuous fiber-reinforced thermoplastic composite micro-foamed product of the present invention comprises the following steps:
  • thermoplastic polymer thin-layer prepreg (1) compounding the widened continuous fiber and thermoplastic polymer to form a fiber-reinforced thermoplastic polymer thin-layer prepreg;
  • FIG. 1 it is a schematic diagram of the main molding steps of the continuous fiber reinforced thermoplastic composite micro-foaming product of the present invention. The foaming is maintained, and finally a microporous laminate with a specially oriented microcellular structure is obtained.
  • a molding device for a continuous fiber reinforced thermoplastic composite micro-foaming product of the present invention comprises a controller, a molding die, a pressure device and a supercritical fluid injection device, the controller and the molding die, the supercritical fluid injection device and the pressure device Connected;
  • the forming mold includes a matching upper mold 4 and a lower mold 10, an inner mold core 6 arranged above the molded product, and the inner mold core 6 is connected with a pressure device, and the pressure device drives the inner mold core 6 to move between the upper and lower molds ;
  • the upper mold 4 is provided with a first gas channel 3
  • the inner mold core 6 is provided with a second gas channel 8
  • the first gas channel 3 is connected to the supercritical fluid injection device.
  • FIG. 4 is a flow chart of the control principle of the molding device of the present invention, the controller controls the heating and cooling of the molding mold, and the opening and closing of the gas channel of the molding mold. Shutdown, and the operation of the pressure device (not shown in the figure, the press in the prior art can be used) and the supercritical injection device.
  • Figure 2 shows a schematic diagram of the structure of the molding die of this embodiment, which mainly includes an inner core control frame 1, an inner core connector 2, a first gas channel 3, an upper die 4, a clamping core 5, and an inner core. 6. Sealing member 7, second gas channel 8 and lower mold 10, etc. Sealing member 7 is provided at the joint of upper mold 4 and lower mold 10, and the second gas channel 8 is perpendicular to the molded product.
  • the pressure device is connected with the inner core 6 through the inner core control frame 1 and the inner core connector 2, thereby driving the inner core to move up and down; the inner core connector 2 passes through the top wall of the upper die 4 and the inner core 6 Connected, the sealing through the position of the upper mold 4 can be achieved using the prior art.
  • the preforms are stacked horizontally into the lower mold 10 and the clamping mold core 5 according to the rules, and the upper mold 4 and the inner mold core 6 move together until they contact the preforms. At this time, the upper outer mold 4 and the lower mold 10 are close to each other. A closed space is formed under the action of the sealing member 7 .
  • the clamping core 5 is arranged around the preform.
  • the mold starts to preheat and the mold is evacuated through the first gas channel 3 and the second gas channel 8.
  • the inner core 6 is connected to the inner core through the inner core control frame 1.
  • the joint action of part 2 starts to move downward, and continues to press the prefabricated parts.
  • the heating temperature, the pressing pressure and the pressing time can be controlled in sections. At this time, the prepreg in the mold is gradually and uniformly plasticized;
  • the inner core 6 starts to move upward through the joint action of the inner core control frame 1 and the inner core connector 2, the first gas channel 3 and the second gas channel 8 are opened, and the supercritical fluid Through the first gas channel 3 and the second gas channel 8, when more than half of the supercritical fluid in the mold is discharged, the upper and outer molds 4 move upward, the molds are fully opened, and the cooled product is taken out.
  • the action of the inner mold core 6 and the upper outer mold 4 and the discharge of the gas during the mold opening process of the mold may be synchronized or there may be a certain time difference.
  • the clamping cores 5 in the mold can be combined to facilitate the removal of the product.
  • the gas channels 3 and 8 of the above-mentioned mold are opened during the mold opening process to discharge the supercritical fluid, and the product expands in the up-down direction.
  • the inner mold core 6 will withstand a certain amount of After the gas back pressure, the inner mold core 6 moves slowly, and the running stroke of the inner mold core is controllable. Finally, the upper outer mold 4 is opened.
  • the clamping cores 5 in the mold can be combined to facilitate the removal of the product.
  • FIG. 3 is a schematic structural diagram of the supercritical fluid injection device of the present invention, which mainly includes a pressure gauge 11, a controller 12, a filter 13, a gas source 14, a refrigeration system 15, a high-pressure pump 16, a flow controller 17, a temperature A controller 18, a control valve 19, a gas storage device 20, a gas inlet 21, a mold controller 22, a gas outlet 23, a condenser 24, a back pressure valve 25 and the like are composed.
  • the mold controller 22 is provided with a high-pressure oil cylinder driving device to realize the movement of the inner layer of the mold.
  • the inlet 21 and the outlet 23 of the mold can be connected with the first gas channel 3 to realize the injection and discharge of the supercritical fluid.
  • polycarbonate PC is used as the matrix, and the PC material is put into a Hack torque rheometer and tested at a temperature of 200 to 300. At a low rotation speed of 5 rpm, the change of its equilibrium torque value and temperature is obtained. relationship, its equilibrium torque value at 250 degrees is 11.8N*m, so it is determined that its suitable melt processing temperature is determined to be 250 degrees.
  • T700 (12K) carbon fiber as a reinforcement, the obtained product is a T700/PC micro-foamed sheet, and the fiber content is 50wt%.
  • the above-mentioned molding device is used for molding, and its main preparation process includes:
  • T700 carbon fiber is widened and pre-compounded with PC online to form a T700/PC unidirectional prepreg tape, the thickness of which is 20 microns, the width is 30 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 50wt%;
  • pre-press After laying 101 layers of fiber prepreg tapes in the 0-degree direction, pre-press to form a preform of fiber-reinforced thermoplastic polymer sheet; the thickness of the preform is about 2 mm.
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 200 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • a microcellular foamed material with a sandwich structure is prepared according to the prior art, which comprises upper and lower layers of carbon fiber reinforced polymer and an intermediate polymer foamed material.
  • the proportion of raw materials of the final product refers to Example 1, the upper and lower layers are each 0.72mm thick, and a method similar to Example 1 is adopted, but no supercritical fluid is introduced, and the intermediate foam layer is prepared from the PC matrix used , its foaming is according to the prior art, its process conditions refer to Example 1, the thickness of the PC product obtained is 6.56mm, and the fiber content of the product obtained after combining the two types of materials is also 50%.
  • T700 carbon fiber is widened and pre-compounded with PC online to form a T700/PC unidirectional prepreg tape, the thickness of which is 20 microns, the width is 30 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 70wt%;
  • the preparation process of the intermediate foam layer is as follows:
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 200 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • the second gas channel 8 is opened and the supercritical fluid is discharged, the product starts to expand along the up and down direction, the inner core of the mold is subjected to the force and slowly opens under the action of the control device, and its movement stroke is 6mm; when the deflation process is halfway through , the upper outer mold is opened, and the gas is completely released.
  • This comparative example is basically the same as Example 1, except for the fibers.
  • This comparative example is an existing common long-fiber reinforced polymer foam product with a fiber content of 50% and a fiber length of 12 mm (discontinuous fibers). Its main technological process and parameters are also adopted in this embodiment 1, the main difference is that the prepreg tape in step (1) is cut to form 12mm long fiber reinforced PC pellets, and then the pellets are pre-pressed in step (2). form a prefab.
  • Comparative Example 1 and Comparative Example 2 are relatively widely used technical means in the field, and the present invention is listed as a comparison on the basis of maintaining the same characteristics as Example 1 to the greatest extent, so as to compare the final effect.
  • This comparative example is basically the same as Example 1, the difference lies in the raw material, and this comparative example does not use a reinforcing body.
  • the materials used in this comparative example are all PC films, and the rest are prepared by referring to the process of Example 1.
  • the obtained products were tested for tensile properties and interlaminar shear strength. The test results are shown in Table 1.
  • this comparative example is specifically listed.
  • PC is used as the matrix
  • T700 (12K) carbon fiber is used as the reinforcement.
  • the devices involved include a mold as shown in FIG. 2 , a press for installing the mold, and a supercritical fluid injection and control device as shown in FIG. 3 .
  • T700 carbon fiber is widened and pre-compounded with PC online to form a T700/PC unidirectional prepreg tape, the thickness of which is 20 microns, the width is 30 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 50wt%;
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 200 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • the preform is stabilized to 220 degrees and held for 10 minutes, then cooled to 180 degrees and held for 10 minutes, the first gas channel 3 and the second gas channel 8 are opened and the supercritical fluid is discharged, and the product begins to expand along the up and down direction,
  • the inner core of the mold is subjected to the force and slowly opened under the action of the control device, and its movement stroke is 6mm; when the deflation process is halfway through, the upper and outer molds are opened, and the gas is completely released.
  • a T700/PC micro-foamed product with an up-down oriented micro-cellular structure was obtained, and the thickness of the final product was 8 mm;
  • this comparative example is specifically listed.
  • PC is used as the matrix
  • T700 (12K) carbon fiber is used as the reinforcement.
  • the devices involved include a mold as shown in FIG. 2 , a press for installing the mold, and a supercritical fluid injection and control device as shown in FIG. 3 .
  • T700 carbon fiber is widened and pre-compounded with PC online to form a T700/PC unidirectional prepreg tape, the thickness of which is 20 microns, the width is 30 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 50wt%;
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 200 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • Example 2 In order to compare the effects of the mold and the supercritical fluid injection device of the present invention with Example 1, this comparative example is specifically listed.
  • PC is used as the matrix
  • T700 (12K) carbon fiber is used as the reinforcement.
  • the molding device used in this comparative example includes an ordinary set of molds containing upper and lower mold halves that can be sealed after the molds are closed, and a press for installing the molds. Foaming agent, Dn8 type original powder) is decomposed.
  • T700 carbon fiber is widened and pre-compounded with PC online to form a T700/PC unidirectional prepreg tape, the thickness of which is 20 microns, the width is 30 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 50wt%;
  • This comparative example is basically the same as Example 1, except that the supercritical fluid is not introduced, and other materials are prepared by referring to the process of Example 1.
  • PC is used as the matrix
  • T700 and 12K carbon fibers are used as reinforcements.
  • the obtained product is a T700/PC micro-foamed sheet with a fiber content of 25wt%.
  • the devices involved include a mold as shown in FIG. 2 , a press for installing the mold, and a supercritical fluid injection and control device as shown in FIG. 3 .
  • the above-mentioned molding device is used for molding, and its main preparation process includes:
  • T700 carbon fiber is widened and pre-compounded with PC online to form a T700/PC unidirectional prepreg tape, the thickness of which is 20 microns, the width is 30 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 50wt%;
  • the fiber prepreg tapes are laid in the 0-degree direction, and the PC film with a length of 300 mm, a width of 30 mm and a thickness of 20 microns is laid between every 2 layers, so that the prepreg tapes are laid with 51 layers, 50 layers of PC film are laid, and then pre-pressed to form a preform of fiber-reinforced thermoplastic polymer sheet; the thickness of the preform is about 2mm.
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 200 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • this comparative example is specifically listed.
  • PC is used as the matrix
  • T700 (12K) carbon fiber is used as the reinforcement.
  • the devices involved include a mold as shown in FIG. 2 , a press for installing the mold, and a supercritical fluid injection and control device as shown in FIG. 3 .
  • T700 carbon fiber is widened and pre-compounded with PC online to form a T700/PC unidirectional prepreg tape, the thickness of which is 20 microns, the width is 30 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 50wt%;
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 200 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • the preform is stabilized to 220 degrees and held for 10 minutes, then cooled to 180 degrees and held for 10 minutes, the first gas channel 3 and the second gas channel 8 are opened and the supercritical fluid is discharged, and the product begins to expand along the up and down direction,
  • the inner core of the mold is subjected to the force and slowly opened under the action of the control device, and its movement stroke is 6mm; when the deflation process is halfway through, the upper and outer molds are opened, and the gas is completely released.
  • the utilization rate of fiber strength is the result obtained by comparing and converting the tensile strength of the actual product, the content of the fiber and the thickness of the product (when the width is the same, the thickness directly affects the area) and the theoretical value of the continuous fiber T700 tensile strength of 4900MPA, The strength of the polymer is ignored.
  • the degree of consistency between the alignment direction of fibers in the material and the stretching direction can be basically known, and the utilization degree of continuous fibers in different embodiments can also be reflected.
  • Figure 5 is a schematic diagram of the distribution state of fibers and micropores in the product of the present invention. It can be seen that the microporous layer and the fiber layer in the product are alternately distributed, and the distribution is uniform, indicating that the formation of the micropores did not damage the original preform. fiber distribution.
  • Figure 6 is the actual distribution state of the fibers in the product of the present invention. It can be seen from Figure 6 that although it is difficult to break the fiber layer and the microporous layer on a plane due to the characteristics of the sample, and at the same time, the fibers cannot be kept vertically arranged. As a result, it oscillates when taking SEM pictures, making the fiber layer appear slightly thicker and blocking the cells, but it can still be seen that the arrangement of the fibers is still parallel, maintaining its state in the prepreg.
  • polypropylene PP is used as the matrix, and the PP material is put into a Hack torque rheometer and tested at a temperature of 120 to 220. At a low speed of 5 rpm, the relationship between its equilibrium torque value and temperature can be obtained. , its equilibrium torque value at 175 degrees is 10.5N*m, so it is determined that its suitable melt processing temperature is 175 degrees.
  • the obtained product is a GF/PP micro-foamed sheet, and the fiber content is 30wt%.
  • the above-mentioned molding device is used for molding, and its main preparation process includes:
  • the glass fiber is pre-compounded with PP on-line after widening to form a GF/PP unidirectional prepreg tape with a thickness of 40 microns, a width of 30 mm and a length of 300 mm, in which the content of glass fiber is controlled at 30wt% ;
  • pre-press After laying 101 layers of fiber pre-impregnated tapes in the 0-degree direction, pre-press to form a preform of a fiber-reinforced thermoplastic polymer sheet; the thickness of the preform is about 4 mm.
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 140 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • polyethylene terephthalate PET is used as the matrix, and the PET material is put into a Hack torque rheometer and tested at a temperature of 180 to 280. At a low rotation speed of 5 rpm, the equilibrium rotation is known. The relationship between torque value and temperature, its equilibrium torque value at 235 degrees is 11.4N*m, so it is determined that its suitable melt processing temperature is 235 degrees.
  • Aramid fiber (AF-1313) was used as reinforcement, and the obtained product was a micro-foamed sheet of AF/PET, and the fiber content was 60wt%.
  • the above-mentioned molding device is used for molding, and its main preparation process includes:
  • the aramid fiber is pre-compounded with PET online after widening to form an AF/PET unidirectional prepreg tape with a thickness of 30 microns, a width of 30 mm, and a length of 300 mm.
  • the content of the aramid fiber is controlled at 60wt%;
  • pre-press After laying 101 layers of fiber prepreg tapes in the 0-degree direction, pre-press to form a preform of fiber-reinforced thermoplastic polymer sheet; the thickness of the preform is about 3 mm.
  • carbon dioxide is injected into the mold at a speed of 50 milliliters per minute at a temperature of 200 degrees and a pressure of 15MPA through the supercritical fluid injection and control device;
  • polyethylene naphthalate PEN is used as the matrix, and the PEN material is put into a Hack torque rheometer and tested at a temperature of 220 to 320, and its equilibrium torque is obtained at a low speed of 5 rpm.
  • the relationship between the value and the temperature, its equilibrium torque value at 280 degrees is 10.9N*m, so it is determined that the suitable melt processing temperature is 280 degrees.
  • the obtained product is a CF/PEN micro-foamed sheet with a fiber content of 50 wt%.
  • the above-mentioned molding device is used for molding, and its main preparation process includes:
  • T800 carbon fiber is widened and pre-compounded with PEN online to form a T800/PEN unidirectional prepreg tape, the thickness of which is 50 microns, the width is 300 mm, and the length is 300 mm, and the content of carbon fiber is controlled at 50wt%;
  • thermoplastic polymer sheet preform After laying 101 layers of fiber prepreg tapes alternately in the 0-degree and 90-degree directions, pre-press to form a fiber-reinforced thermoplastic polymer sheet preform; the thickness of the preform is about 5 mm.
  • nitrogen is injected into the mold at a speed of 50 milliliters per minute at a temperature of 230 degrees and a pressure of 35MPA through the supercritical fluid injection and control device;
  • the second gas channel 8 is opened and the supercritical fluid is discharged, the product begins to expand along the up and down direction, the inner core of the mold is subjected to the force and slowly opened under the action of the control device, and its movement stroke is 10mm; when the deflation process is halfway through , the upper outer mold is opened, and the gas is completely released.
  • the molding method of the above-mentioned embodiment of the present invention effectively solves the problem of continuous fiber distribution in the foamed product, the fiber damage rate is low, the lamination and foaming are completed in the same mold, the production efficiency is high, and the product is It has fine pores and excellent mechanical properties, which can be directly applied on a large scale.
  • the density of the manufactured continuous fiber reinforced thermoplastic microfoamed product is between 0.01 and 1 times that of the ordinary fiber reinforced product; the fiber layer and the cellular layer of the product are delaminated at the microscopic level; the distribution of fibers in the final product and its distribution in the preform
  • the distribution in the cell layer can be kept consistent; the density of micropores in the cell layer is above 10 6 cells/cm 3 .

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Abstract

本发明公开了一种连续纤维增强热塑性复合物微发泡制品及其成型方法和装置，将连续纤维经过宽展、复合等步骤形成纤维预浸带；将纤维预浸带按照确定的规则铺放后，经预压形成纤维增强热塑性聚合物的预制件；将预制件经过加热加压并抽真空后通入超临界流体，按确定的工艺保持一定的时间；将超临界流体沿确定的方向快速放出，获得具有特殊微孔结构的纤维增强微发泡制品。本发明有效解决了连续纤维在发泡制品内部分布的问题，纤维损伤率低，其层合与发泡在同一模具内完成，生产效率高，其制品的泡孔细腻，力学性能优异，可直接规模化应用。

Description

一种连续纤维增强热塑性复合物微发泡制品及其成型方法和装置 技术领域
本发明涉及复合材料及其加工成型，特别是涉及一种连续纤维增强热塑性复合物微发泡制品的成型方法。
背景技术
微纳米尺度的泡孔除具有减重、隔热、隔音、减震、消除缩痕以及尺寸稳定等传统泡沫的优点之外，还能够赋予聚合物材料某种优异性能，现已广泛应用于包装、建筑、汽车、航天航空、运动器材等诸多领域，但也常因性能不足而受到一定限制，特别是力学性能。利用纤维作为增强体是解决聚合物材料力学性能不足的一个途径。目前，纤维增强聚合物复合材料因具有力学性能高、密度小、耐腐蚀、抗疲劳、可回收、可焊接、环境友好、成型周期短等突出优点，已经成为航空航天、军工等领域大力发展及广泛应用的关键材料。这其中，和热固性复合材料相比，连续纤维增强热塑性复合材料(FRTP)具有成型周期短，抗冲性能好，以及易于修复和回收等优点，表现出强劲的发展势头。
虽然，具有微纳孔特征的FRTP将兼具传统FRTP和微孔发泡制品两方面的优点。然而，现有的纤维增强热塑性微孔制品往往采用如下两种方法来加工：(1)发泡过程单独完成，也即材料的发泡过程及成型过程是分步完成的，它往往采用发泡制品和纤维增强材料分步制备然后再粘合或复合从而形成“三明治”结构，这类制品的分层尺寸往往较大，而这种宏观上的分层造成材料的一致性较差，从本质上说，这类制品所包含的材料并不单一，其性能与表现基本上为两类材料的加和；(2)另一类纤维增强热塑性微发泡制品虽然是在制品的成型过程中在线发泡的，但其包含的纤维多为短纤维或长纤维，此时的纤维在热塑性聚合物中的取向是不一致的，这使得普通使用短纤维或长纤维增强热塑性微发泡制品中的纤维性能发挥并不明显。
发明内容
发明目的：本发明的目的之一是提供一种连续纤维增强热塑性复合物微发泡制品，综合性能优异；本发明的目的之二是提供一种连续纤维增强热塑性复合物微发泡制品的成型方法，可以制备得到综合性能优异的发泡制品；本发明的目的之三是提供一种连续纤维增强热塑性复合物微发泡制品的成型装置。
技术方案：本发明提供了一种连续纤维增强热塑性复合物微发泡制品，以热塑性聚合物为基体，连续纤维为增强相；所述微发泡制品具有单一取向的微孔结构，连续纤维呈平行排列。
即：该制品由连续纤维与聚合物组成，发泡制品具有特殊沿某单一方向取向的微孔结构，纤维的排列与微孔的分布均表现为均匀一致的特征，且在微米尺度上具有分层结 构。
其中，上述制品中，泡孔取向的方向沿制品的厚度方向。微发泡制品中连续纤维平行排列，且连续纤维含量为10～60wt％。
本发明还提供了一种连续纤维增强热塑性复合物微发泡制品的成型方法，包括以下步骤：
(1)将经宽展后的连续纤维与热塑性聚合物进行复合，形成纤维增强热塑性聚合物薄层预浸带；
(2)铺放预浸带形成预浸料，对预浸料进行预压处理，形成纤维增强热塑性聚合物预制件；
(3)将预制件放置于模具中，真空状态下进行加热加压处理，向模具中注入超临界流体，注入超临界流体后进行保温保压处理；
(4)将预制件进行冷却，排出超临界流体，得到具有特殊取向微孔结构的纤维增强微发泡制品。
上述步骤(1)中，所使用的连续纤维可以是碳纤维、玻璃纤维、玄武岩纤维、芳纶纤维、超高分子量聚乙烯纤维以及其它由聚合物纺丝而来的纤维中的一种或几种；其同步宽展及复合的纤维可以是一束或多束；每束纤维的丝束可在1K到128K之间。用于复合的热塑性聚合物可以是PEEK、PPS、PA、PC、PEN、PET、PBT、PP中的一种或几种，可以是粉状或薄膜状供料。
其中，步骤(1)中，纤维增强热塑性聚合物薄层预浸带的厚度在10μm～100μm，纤维的含量为10～80wt％。
步骤(2)中，纤维预浸带的铺放是在保持一定预紧力下进行的，优选地，预紧力为0.01～0.05MPa；其铺放角度可以是0到90度之间的任一角度，不同层之间的铺放角度可以相同或不同。其中，0.01～0.05MPa的预紧力可以保证预浸带的平整铺放，预紧力太大则可能使预浸带存在一直存在着拉应力。
优选地，铺放预浸带时，相邻预浸带之间铺设有聚合物薄膜或片材，薄膜或片材的材质可以与预浸料基体相同或不同，但聚合物薄膜或片材的熔点不高于预浸料，两者的熔点差值在10度以内；即相邻预浸带之间铺设的聚合物薄膜或片材的熔点与预浸料熔点差值≤10℃。
其中，上述步骤(3)中注入的超临界流体可以是氮气、二氧化碳、或其混合气体。
优选地，步骤(3)中，加热加压处理包括至少包括三个阶段，每阶段温度的增加值以预浸料加热温度峰值与室温之间的差值的1/5～1/3为宜，压力的三个阶段分别在1～2MPA，4～6MPA，以及9～12MPA之间。每阶段的时间可以根据最终制件的厚度来确定，可在5～60分钟之间。进一步地，加热处理包括从室温分阶段加热至预浸料的加热温 度峰值，加压处理至少包括三个阶段，三个阶段分别设置在1～2MPA、4～6MPA以及9～12MPA之间，每个阶段控制时间为5～60min。
其中，所述加热温度峰值T 加热＝T 测±10℃，T 测为将热塑性聚合物在流变试验条件下，5rpm的转速下，平衡转矩值在8～12N*m时对应温度值。即：加热温度峰值T 加热是基于预浸料中的聚合物基体的流变实验来确定的，将预浸料中的聚合物材料放入到转矩流变仪在不同的加热温度下测试，在5rpm的低转速下时平衡转矩值在8～12N*m时的温度值上下10度的范围之内；具体可以将预浸料中的聚合物材料放入到转矩流变仪在聚合物的熔点附近上下50度的范围内测试，在5rpm的低转速下时平衡转矩值在8～12N*m时的温度值上下10度的范围之内。此转矩值意味着此时的材料在很小的转速，也即低剪切速率下，既能够熔融，又能够保持一定的黏度。如果转矩值太大，则温度取值偏低，后期的材料相互融合不好，如果转矩值较小，则温度取值偏高，后期的材料在受压下难以保持纤维的原有排列状态。
优选地，为避免过度的热冲击，步骤(3)中，超临界流体比之前的加热温度低30～50度范围内注入，压力则要在超临界流体的超临界状态之上，注入则恒定速度下进行，其速度不宜过快或过慢，一般整个注入过程在3～5分钟内完成。同时，为了使超临界流体更好的溶入预制件之中，同时也避免预制件的黏度下降过多，将注入超临界流体后的材料稳定到比预浸料加热温度峰值T 加热低20～40度后的温度范围，并保持5～20分钟以使预制件的温度分布均匀；
进一步地，步骤(3)中，向模具中注入预热的超临界流体，预热温度比预浸料加热温度峰值T 加热温度低30～50℃，压力保持在超临界状态之上；注入超临界流体后，将预制件温度稳定在低于预浸料加热温度峰值T 加热温度20～40℃范围内，并保持5～20分钟。
如当介质为二氧化碳时，可将压力保持在10～20MPa；具体的气体介质在超临界状态对应的压力值可通过现有技术轻易实现，在此不再赘述。
步骤(4)中，预制件的冷却过程分2～5个阶段进行，每阶段降温幅度控制在5～10℃，每阶段温度保持时间为5～40min。其中，超临界流体排出的方向和模具打开方向可以相同，也可以不同(如两者方向相互垂直)；超临界流体排出的速度要远超过模具打开的速度。
经过上述成型过程，预浸带形成的预浸料在抽真空条件下分步骤升温并预压的办法来保证预浸物中的纤维保持其精确的构形排列，其最终达到的温度要超过预浸物基体树脂的熔融温度抽真空。
而预浸料在高温下保持一段时间后，经过降低温度后通入经过预热的超临界流体，再次保持一段时间后，再次降低温度并保持一定的时间；其中每次的降温幅度控制在5～10度，降温可以分2～5个阶段进行，依据产品的尺寸情况，保持的时间在5～40分钟之间。
本发明提供的上述成型方法得到的制品密度为同等纤维增强未发泡制品的0.01～1倍之间；纤维和泡孔在微米尺度上有分层；最终制品中纤维的分布和其在预制件中的分布能够保持一致。
本发明还提供了一种连续纤维增强热塑性复合物微发泡制品的成型装置，其包括控制器、成型模具、压力装置和超临界流体注入装置，控制器与成型模具、超临界流体注入装置与压力装置相连；成型模具包括相适配的上模和下模、设于成型制品上方的内模芯，内模芯与压力装置相连，压力装置驱动内模芯在上下模之间运动；所述上模设有第一气体通道，内模芯设有第二气体通道，第一气体通道与超临界流体注入装置相连。即超临界流体经第一气体通道通入模具内部，再经第二气体通道进入成型制品内部；排出时经由第二气体通道、第一气体通道排出。
优选地，成型制品置于下模中，上下模安装形成封闭空间；所述控制器控制模具的加热与冷却、气体通道的打开与关闭、以及压力装置和超临界注入装置的运行。可选的，气体通道上加装高压排气阀，高压排气阀与控制器相连，控制器与高压排气阀相连，从而实现气体通道的开合。
优选地，所述第二气体通道与成型制品相垂直，得到的泡孔取向方向为制品厚度方向。即：使得制品中的连续纤维沿水平方向，制品中的微孔方向与连续纤维相垂直。
其中，内模芯在上下模之间的空间内上下运动，上下运动的行程依照欲发泡程度确定，优选的，为了模具的结构紧凑和强度要求，该行程为预制件厚度的2～5倍，此时，也就意味着，仅靠内模芯运动可以实现预制件发泡的倍率为2～5倍，当发泡倍率要求更高时，通过上模打开来实现。
可选的，本发明的成型模具包括上下两半模具，其中至少有一半模具具有双层结构，两层之间在受力作用下可以作相对运动，模具的内层有机构通到外层的外面，外层安装有高压排气阀，其内外层壁之间有可以相互联通的微小孔隙，微小孔隙分布均匀，其排气方向保持一致；上下模具闭合后在高压排气阀闭合时可以保证通入超临界流体后在压力达到工作压力(前文所述气体的压力)以上时不漏气，在高压排气阀打开后可以保证内层的气体快速排出。
超临界流体注入装置的主要特点为：该装置具有将氮气或二氧化碳中的一种或两种加压控温下达到超临界流体状态，并能够在按设定的温度以恒定的流速或压力注入到上述模具内。
本发明中制备综合性能优异的连续纤维增强热塑性复合物微发泡制品制备难度极大，由于热塑性树脂的粘度一般均高于热固性树脂，这可能会影响了树脂与纤维之间的浸润；发泡可能会破坏树脂与纤维的界面，从而使得纤维在缺少树脂的保护下受损；发泡过程难以控制，发泡的不均匀导致材料性能的变差及均匀性不足；发泡影响到连续纤 维的分布，使最终产品的性能变差或一致性变差等。
而本发明提供了一种连续纤维增强热塑性复合物微发泡制品的成型方法和成型装置，通过整个工艺路线及条件获得具有均匀微孔与纤维分布的FRTP制品的加工方法，其力学性能明显超过普通FRTP制品。
这使用超临界流体来直接加工连续纤维增强热塑性制品则面临的技术难点主要表现在：在发泡过程中不可避免导致纤维因泡孔长大而产生方向或一定角度的偏差，发泡过程很难控制纤维分布的均匀性及一致性等，这些均造成按现有技术加工出来的连续纤维增强热塑性微孔制品中的纤维性能得不到发挥，从而表现为制品的品质及性能下降。
本发明的基本原理在于：纤维宽展后与热塑性聚合物的复合所得的预浸带中的纤维单向一致，预浸带层合或与聚合物薄膜复合后所得的层合板中纤维层分布均匀，之后在受限条件下实现可控发泡，发泡区域集中在预浸带的层间部位，从而，树脂与纤维之间的界面不受损坏，同时，通过严格控制发泡的工艺条件，在装置的配合使用下，使得聚合物能够充分吸收到超临界流体，并按需单向排出，在发泡过程中一方面导致发泡均匀且沿着指定排出方向取向，最终所得泡孔沿气体泄压方向取向后的一致性好，同时，连续纤维的分布几乎不受泡孔长大的破坏及影响，纤维的排列仍然保持着预制件内的状态。更主要的，此时制品的纤维与微孔的层间分层是在微米尺度上的，在宏观上表现为纤维微孔一体化的材料，故其综合性能表现出一定的尺度倍增效应。
有益效果：
本发明制造的连续纤维增强发泡制品，有效解决了连续纤维在发泡制品内部分布的问题，纤维损伤率低，其层合与发泡在同一模具内完成，生产效率高，其制品的泡孔细赋，力学性能优异，可直接规模化应用。
本发明制备得到的连续纤维增强热塑性聚合物微发泡制品具有如下特点：其制品的密度为普通纤维增强制品的0.01～1倍之间；该制品纤维层和泡孔层有微观层面的分层；最终制品中纤维的分布和其在预制件中的分布能够保持一致；泡孔层中的微孔密度在10 6cells/cm 3以上。
本发明有效解决了连续纤维在发泡制品内部分布的问题，和普通的连续纤维增强制品相比，泡孔的存在降低了产品的密度，提高了冲击缓冲性能，它具有发泡制品的隔热、隔音等效果，同时，该工艺及其产品还具有以下优点：(1)因为其发泡过程是在基体熔融后进行的，一定程度上避免了纤维的损伤；(2)因为发泡过程是在受限状态下进行的，发泡对纤维的分布影响较小，纤维的分布比较均匀，一致性好；(3)使用热塑性树脂为基体以及使用超临界流体为发泡介质，整个工艺绿色环保，全程无污染，产品的可回复性强；(4)制品的泡孔细小密集，力学性能保持较好；(5)制品的层合过程与发泡过程是在同一模具内完成，其生产工艺连续化，因而整个生产过程可以规模化应用；(6) 纤维的排列构形得到精准调控，纤维与树脂的界面不受破坏，因而纤维损伤率低，纤维的取向和预定方法一致，这为保证其力学性能提供了可能；(7)制品的分层是在微观层面上的，其层间结合强度和同等无纤维层的发泡产品的强度接近，表明该方法所获产品在实际应用时并不容易出现分层的问题。
附图说明
图1是本发明的连续纤维增强热塑性复合物微发泡制品的主要成型步骤示意图。
图2是本发明的成型模具结构示意图。
图3是本发明的超临界流体注入及控制装置示意图。
图4是本发明成型装置的控制原理流程图。
图5是本发明制得制品的截面结构示意图。
图6是本发明制得制品的截面结构扫描电镜图。
具体实施方式
下面结合实施例对本发明进一步地详细描述。
本发明的一种连续纤维增强热塑性复合物微发泡制品的成型方法，包括以下步骤：
(1)将宽展后连续纤维和热塑性聚合物进行复合，形成纤维增强热塑性聚合物薄层预浸带；
(2)铺设预浸带形成预浸料，对预浸料进行预压处理，形成纤维增强热塑性聚合物预制件；
(3)将预制件放置于模具中，真空状态下进行加热加压处理，向模具中注入超临界流体，后进行保温保压处理；
(4)将预制件进行冷却，排出超临界流体，得到发泡制品。
如图1所示为本发明的连续纤维增强热塑性复合物微发泡制品的主要成型步骤示意图，将预制件放置于模具中，合模后进行抽真空、热压及注入超临界流体，热压保持进行发泡，最终得到具有特殊取向微孔结构的微孔层合板。
本发明的一种连续纤维增强热塑性复合物微发泡制品的成型装置，其包括控制器、成型模具、压力装置和超临界流体注入装置，控制器与成型模具、超临界流体注入装置与压力装置相连；成型模具包括相适配的上模4和下模10、设于成型制品上方的内模芯6，内模芯6与压力装置相连，压力装置驱动内模芯6在上下模之间运动；所述上模4设有第一气体通道3，内模芯6设有第二气体通道8，第一气体通道3与超临界流体注入装置相连。成型制品置于下模10中，上下模安装形成封闭空间；如图4所示是本发明成型装置的控制原理流程图，控制器控制成型模具的加热与冷却、成型模具的气体通道的打开与关闭、以及压力装置(图中未示出，采用现有技术中的压力机即可)和超临界注入装置的运行。
如图2所示为本实施例的成型模具结构示意图，它主要包括内模芯控制架1、内模芯连接件2、第一气体通道3、上模4、夹模芯5、内模芯6、密封件7、第二气体通道8和下模10等，上模4和下模10的盖合处设有密封件7，第二气体通道8与成型制品相垂直。压力装置与内模芯6通过内模芯控制架1和内模芯连接件2相连，从而带动内模芯上下运动；内模芯连接件2穿过上模4的顶壁与内模芯6相连，穿过上模4的位置的密封可采用现有技术实现。
欲成型制品9时，其主要工作原理为：
(1)将预制件按照规则水平堆放到下模10与夹模芯5内，上模4与内模芯6一起运动，直到接触预制件时，此时，上外模4与下模10靠密封件7的作用下形成了密闭的空间。其中，夹模芯5设置在预制件的四周。
(2)模具开始预热并通过第一气体通道3和第二气体通道8对模具内抽真空，当模具加热到指定温度后，内模芯6通过内模芯控制架1和内模芯连接件2的共同作用开始向下运动，继续对预制件施压，加热温度、施压压力与施压时间可以分段控制，此时模具内的预浸料逐渐均匀塑化；
(3)再通过第一气体通道3和第二气体通道8将超临界流体在可控的温度压力与流速下注入到模具内，此时，可以继续分段控制模具内的温度与压力；
(4)在一定的时间之后，内模芯6通过内模芯控制架1和内模芯连接件2的共同作用开始向上运动，第一气体通道3和第二气体通道8打开，超临界流体通过第一气体通道3和第二气体通道8排出，当模具内的超临界流体排出超过一半以后，上外模4向上运动，模具全部打开，冷却后的制品取出。
其中，该模具在开模过程中的内模芯6和上外模4的动作以及气体的排出三者之间可以同步也可以存在一定的时间差。模具内的夹模芯5可以采用组合的方式，以利于取出制品。
为了使制品的发泡处于一种受限制状态，上述模具在开模过程中气体通道3和8打开并排出超临界流体，制品沿着上下方向膨胀，此时，内模芯6会承受一定的气体反压力，之后，内模芯6缓慢运动，内模芯的运行行程可控。最后，上外模4打开。
模具内的夹模芯5可以采用组合的方式，以利于取出制品。
如图3所示为本发明超临界流体注入装置的结构示意图，它主要包括压力表11、控制器12、过滤器13、气源14、制冷系统15、高压泵16、流量控制器17、温度控制器18、控制阀19、储气装置20、气体通入模具进口21、模具控制器22、气体流出模具出口23、冷凝器24、背压阀25等组成。其中，模具控制器22内设有高压油缸驱动装置以实现模具内层的运动。其中，模具的进口21和出口23可以与第一气体通道3相连，实现超临界流体的注入和排出。
其主要工作原理为：气源14中的氮气或二氧化碳中的一种或两种在控制器12的作用下通过过滤器13后，进入制冷系统15，气体会下降到指定温度，之后在高压泵16的作用下增压转变为超临界状态，之后经流量控制器17调整到恒速状态并在温度控制器18的作用下加热到指定温度，此时的超临界流体在控制阀19的作用下进入到储气装置20内，并进而在储气装置20的作用下，在指定压力和速率下通过进口21按需进入到模具内。模具控制器可以实现模具内层的按需动作，之后，当需要超临界流体从模具中排出时，它流经模具出口23，再经过冷凝器24的作用，通过背压阀25重新回到控制器12中，实现气体的循环利用。
其中，成型装置未详细描述之处均可通过现有技术轻易实现，在此不再进行赘述。
以下实施例和对比例中的原料和试剂均为市售。
实施例1：
本实施例以聚碳酸酯PC为基体，将PC材料放入到哈克转矩流变仪中在200～300温度下测试，在5rpm的低转速下时获知其平衡转矩值与温度的变化关系，其在250度时的平衡转矩值为11.8N*m，因此确定其适宜的熔融加工温度确定为250度。以T700(12K)碳纤维作为增强体，所得制品为T700/PC的微发泡板材，纤维含量为50wt％。
采用上述成型装置进行成型，其主要的制备过程包括：
(1)将T700碳纤维宽展后与PC在线预复合，形成T700/PC单向预浸带，其厚度为20微米，宽度为30毫米，长度为300毫米，其中碳纤维的含量控制在50wt％；
(2)将纤维预浸带均按照0度方向铺放101层后，预压形成纤维增强热塑性聚合物板材的预制件；预制件的厚度约为2mm。
(3)将预制件放置到安装在压力机上的模具内，抽真空后加热到100度并加压到1MPA，保持5分钟后，升温到150度再加压到5MPA，保持5分钟后，继续升温到200度再加压到10MPA，保持5分钟后，升温到250度，并保持20分钟；
(4)将二氧化碳经过超临界流体注入及控制装置，在200度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到210度后保持5分钟，之后冷却到200度保持5分钟，再冷却到190度保持5分钟，继续冷却到180度保持5分钟后，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为6mm；放气过程进行到一半时，上外模打开，气体被完全放出。
从而，获得了具有上下取向状微孔结构的T700/PC微发泡制件，其最终产品的厚度为8毫米；对所制得的制品进行拉伸性能及层间剪切强度等相关测试，测试结果见表1。
对比例1：
本对比例按现有技术制备具有三明治结构的微孔发泡材料，其包含上下两层的碳纤维增强聚合物和中间的聚合物发泡材料。其最终制品的原料占比参照实施例1，上下两层各厚0.72mm，采用与实施例1类似的方法，但未通入超临界流体，中间的发泡层采用的PC的基体制备而来，其发泡按现有技术，其工艺条件参照实施例1，获得的PC制品的厚度为6.56mm，最终将两类材料复合后所得制品的纤维含量也为50％。
其中，上下层的制备过程如下：
(1)将T700碳纤维宽展后与PC在线预复合，形成T700/PC单向预浸带，其厚度为20微米，宽度为30毫米，长度为300毫米，其中碳纤维的含量控制在70wt％；
(2)将纤维预浸带均按照0度方向铺放36层后，预压形成纤维增强热塑性聚合物板材的预制件；
(3)将预制件放置到安装在压力机上的模具内，抽真空后加热到100度并加压到1MPA，保持5分钟后，升温到150度再加压到5MPA，保持5分钟后，继续升温到200度再加压到10MPA，保持5分钟后，升温到250度，并保持20分钟；
(4)将预制件稳定到210度后保持5分钟，之后冷却到200度保持5分钟，再冷却到190度保持5分钟，继续冷却到180度保持5分钟后，第一气体通道3和第二气体通道8打开，上外模打开，制品取出。
中间发泡层的制备过程如下：
(1)将厚度为20微米，宽度为30毫米，长度为300毫米的PC薄膜按照0度方向铺放28层后，预压形成PC板材的预制件；
(2)将预制件放置到安装在压力机上的模具内，抽真空后加热到100度并加压到1MPA，保持5分钟后，升温到150度再加压到5MPA，保持5分钟后，继续升温到200度再加压到10MPA，保持5分钟后，升温到250度，并保持20分钟；
(3)将二氧化碳经过超临界流体注入及控制装置，在200度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(4)将预制件稳定到210度后保持5分钟，之后冷却到200度保持5分钟，再冷却到190度保持5分钟，继续冷却到180度保持5分钟后，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为6mm；放气过程进行到一半时，上外模打开，气体被完全放出。
对比例2：
本对比例与实施例1基本相同，不同之处在于纤维。
本对比例为现有普通的长纤维增强聚合物发泡制品，其纤维的含量为50％，纤维的长度为12mm(非连续纤维)。其主要工艺流程及参数也采照本实施例1，主要不同在于 步骤(1)中的预浸带切断形成12mm的长纤维增强PC粒料，然后在步骤(2)中将粒料预压后形成预制件。
对比例1和对比例2属于本领域内的较为广泛应用的技术手段，本发明在最大程度的保持和实施例1的相同特性的基础上列为对比，以便比较最终效果。
对比例3：
本对比例与实施例1基本相同，不同之处在于原料，本对比例未采用增强体。
本对比例所使用的材料全部为PC薄膜，其余均参照实施例1的流程来制备材料。将所制得的制品进行拉伸性能及层间剪切强度等相关测试，测试结果见表1。
对比例4：
为了和实施例1对比本发明的相关工艺，特列举本对比例。本对比例以PC为基体，T700(12K)碳纤维作为增强体，所得制品为T700/PC的微发泡板材，纤维含量为50wt％。其涉及的装置包括如图2所示的模具、安装模具的压力机、以及如图3所示的超临界流体注入及控制装置等。
其主要的制备过程包括：
(1)将T700碳纤维宽展后与PC在线预复合，形成T700/PC单向预浸带，其厚度为20微米，宽度为30毫米，长度为300毫米，其中碳纤维的含量控制在50wt％；
(2)将纤维预浸带均按照0度方向铺放101层后，预压形成纤维增强热塑性聚合物板材的预制件；
(3)将预制件放置到安装在压力机上的模具内，抽真空后直接升温到250度，并保持40分钟；
(4)将二氧化碳经过超临界流体注入及控制装置，在200度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到220度后保持10分钟，之后冷却到180度保持10分钟，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为6mm；放气过程进行到一半时，上外模打开，气体被完全放出。从而，获得了具有上下取向状微孔结构的T700/PC微发泡制件，其最终产品的厚度为8毫米；
最后，对所制得的制品进行拉伸性能及层间剪切强度等相关测试，测试结果见表1。
对比例5：
为了和实施例1对比本发明中的模具打开过程的效果，特列举本对比例。本对比例以PC为基体，T700(12K)碳纤维作为增强体，所得制品为T700/PC的微发泡板材，纤维含量为50wt％。其涉及的装置包括如图2所示的模具、安装模具的压力机、以及如图3所示的超临界流体注入及控制装置等。
其主要的制备过程包括：
(1)将T700碳纤维宽展后与PC在线预复合，形成T700/PC单向预浸带，其厚度为20微米，宽度为30毫米，长度为300毫米，其中碳纤维的含量控制在50wt％；
(2)将纤维预浸带均按照0度方向铺放101层后，预压形成纤维增强热塑性聚合物板材的预制件；
(3)将预制件放置到安装在压力机上的模具内，抽真空后加热到100度并加压到1MPA，保持5分钟后，升温到150度再加压到5MPA，保持5分钟后，继续升温到200度再加压到10MPA，保持5分钟后，升温到220度，并保持20分钟；
(和实施例1相比，本对比例的上述加热温度未按照本发明所描述的加热温度峰值的确定方法加以选择；)
(4)将二氧化碳经过超临界流体注入及控制装置，在200度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到210度后保持5分钟，之后冷却到200度保持5分钟，再冷却到190度保持5分钟，继续冷却到180度保持5分钟后，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯和上外模同时打开，气体被完全放出，最终控制模具的开模行程为6毫米。
从而，获得了具有微孔结构的T700/PC微发泡制件，其最终产品的厚度也为8毫米；对本对比例所制得的制品进行拉伸性能及层间剪切强度等相关测试，测试结果见表1。
对比例6：
为了和实施例1对比本发明中的模具及超临界流体注入装置的效果，特列举本对比例。本对比例以PC为基体，T700(12K)碳纤维作为增强体，所得制品为T700/PC的微发泡板材，纤维含量为50wt％。
本对比例采用的成型装置包括普通的含有上下两半模且合模后能够密封的模具一套以及安装模具的压力机等，其气体使用化学发泡剂(分解温度在200度的AC高温发泡剂，Dn8型原粉)分解产生。
其主要的制备过程包括：
(1)将T700碳纤维宽展后与PC在线预复合，形成T700/PC单向预浸带，其厚度为20微米，宽度为30毫米，长度为300毫米，其中碳纤维的含量控制在50wt％；
(2)将纤维预浸带均按照0度方向铺放101层后，预压形成纤维增强热塑性聚合物板材的预制件；
(3)将预制件和化学发泡剂放置到安装在压力机上的模具内，抽真空后加热到100度并加压到1MPA，保持5分钟后，升温到150度再加压到5MPA，保持5分钟后，继续升温到200度再加压到10MPA，保持5分钟后，升温到250度，并保持20分钟；
(4)将预制件稳定到210度后保持5分钟，之后，冷却到200度保持5分钟，再冷却到190度保持5分钟，继续冷却到180度保持5分钟后，模具的上模直接快速打开，气体被完全放出。从而，获得了T700/PC发泡制件；对所制得的制品进行拉伸性能及层间剪切强度等相关测试，测试结果见表1。
对比例7：
本对比例与实施例1基本相同，不同之处在于未通入超临界流体以外，其余均参照实施例1的流程来制备材料。
实施例2：
本实施例以PC为基体，T700、12K碳纤维作为增强体，所得制品为T700/PC的微发泡板材，纤维含量为25wt％。其涉及的装置包括如图2所示的模具、安装模具的压力机、以及如图3所示的超临界流体注入及控制装置等。
采用上述成型装置进行成型，其主要的制备过程包括：
(1)将T700碳纤维宽展后与PC在线预复合，形成T700/PC单向预浸带，其厚度为20微米，宽度为30毫米，长度为300毫米，其中碳纤维的含量控制在50wt％；
(2)将纤维预浸带均按照0度方向铺放，每2层之间铺放长度为300毫米，宽度为30毫米，厚度为20微米的PC薄膜，这样预浸带铺放51层，PC薄膜铺放50层，之后，预压形成纤维增强热塑性聚合物板材的预制件；预制件的厚度约为2mm。
(3)将预制件放置到安装在压力机上的模具内，抽真空后加热到100度并加压到1MPA，保持5分钟后，升温到150度再加压到5MPA，保持5分钟后，继续升温到200度再加压到10MPA，保持5分钟后，升温到250度，并保持20分钟；
(4)将二氧化碳经过超临界流体注入及控制装置，在200度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到210度后保持5分钟，之后，冷却到200度保持5分钟，再冷却到190度保持5分钟，继续冷却到180度保持5分钟后，气体通道3和8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为6mm；放气过程进行到一半时，上外模打开，气体被完全放出。
从而，获得了具有上下取向状微孔结构的T700/PC微发泡制件，其最终产品的厚度为8毫米。
对比例8：
为了和实施例2对比本发明的相关工艺，特列举本对比例。本对比例以PC为基体，T700(12K)碳纤维作为增强体，所得制品为T700/PC的微发泡板材，纤维含量为25wt％。 其涉及的装置包括如图2所示的模具、安装模具的压力机、以及如图3所示的超临界流体注入及控制装置等。
其主要的制备过程包括：
(1)将T700碳纤维宽展后与PC在线预复合，形成T700/PC单向预浸带，其厚度为20微米，宽度为30毫米，长度为300毫米，其中碳纤维的含量控制在50wt％；
(2)将纤维预浸带均按照0度方向铺放，每2层之间铺放长度为300毫米，宽度为30毫米，厚度为20微米的PC薄膜，这样预浸带铺放51层，PC薄膜铺放50层，之后，预压形成纤维增强热塑性聚合物板材的预制件；
(3)将预制件放置到安装在压力机上的模具内，抽真空后升温到220度，并保持40分钟；
(4)将二氧化碳经过超临界流体注入及控制装置，在200度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到220度后保持10分钟，之后冷却到180度保持10分钟，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为6mm；放气过程进行到一半时，上外模打开，气体被完全放出。
从而，获得了具有上下取向状微孔结构的T700/PC微发泡制件，其最终产品的厚度为8毫米。
将上述实施例1、2以及对比例1～8所制得的制品进行拉伸性能及层间剪切强度等相关测试，测试结果汇总见表1。
表1、几种制品的综合比较
Figure PCTCN2022076286-appb-000001
Figure PCTCN2022076286-appb-000002
Figure PCTCN2022076286-appb-000003
注意纤维强度的利用率是实际制品所得拉伸强度、纤维的含量以及制品的厚度(宽度一致时，厚度直接影响到面积)和连续纤维T700拉伸强度的理论值4900MPA进行对比折算后所得结果，聚合物的强度被忽略。通过纤维强度的利用率可基本获知纤维在材料内部的排列方向与拉伸方向的一致程度，也可以体现不同实施方案对连续纤维的利用程度。
通过上表1的测试结果可以看出，本发明的T700/PC微孔制品的拉伸强度可与相应的实心制品相当，也接近该类材料的理论计算结果，表明该工艺极大的发挥了纤维的特性，同时，该制品具有很好的可压缩能力，表明该工艺中微孔的分布较均匀，也发挥出了微孔的优点。另外，从层间剪切强度测试可知，实施例的微孔层与纤维层可以较好的分离，表示微孔层与纤维层的控制精确。注意，层间剪切强度测试显示为弯曲破坏时，表明这类产品分层较困难，这应该归于纤维及微孔的分布不均匀，另外，如果层间剪切强度偏低，假如低与材料正常值，则表明层间的结合不好。对比例2的层间剪切强度虽然有所提高，但这显然与其中的长纤维在其中的混杂分布有关，其拉伸强度十分低，故不能很好利用纤维的增强作用。因而本发明所提及的这类制品具有力学性能独特的优势，从而具有优异的应用前景。
图5为本发明制品内部纤维与微孔分布状态示意图，这其中可以看到，制品中的微孔层与纤维层交替分布，且分布均匀，表明微孔的形成时没有破坏原有预制件中纤维的分布状态。图6为本发明制品内部纤维的实际分布状态，通过图6可知，尽管由于该样品的特点，欲将纤维层与微孔层断在一个平面上较为困难，同时，纤维无法保持竖直排列，造成其在做SEM拍照时有所摆动使纤维层显得略厚，并对泡孔有所遮挡，但仍然可以看出，其纤维的排列仍然平行，保持了其在预浸料中的状态。
实施例3：
本实施例以聚丙烯PP为基体，将PP材料放入到哈克转矩流变仪中在120～220温度下测试，在5rpm的低转速下时获知其平衡转矩值与温度的变化关系，其在175度时的平衡转矩值为10.5N*m，因此确定其适宜的熔融加工温度确定为175度。
以玻璃纤维(E-Glass Fiber)作为增强体，所得制品为GF/PP的微发泡板材，纤维含量为30wt％。
采用上述成型装置进行成型，其主要的制备过程包括：
(1)将玻璃纤维宽展后与PP在线预复合，形成GF/PP单向预浸带，其厚度为40 微米，宽度为30毫米，长度为300毫米，其中玻璃纤维的含量控制在30wt％；
(2)将纤维预浸带均按照0度方向铺放101层后，预压形成纤维增强热塑性聚合物板材的预制件；预制件的厚度约为4mm。
(3)将预制件放置到安装在压力机上的模具内，抽真空后加热到50度并加压到1MPA，保持5分钟后，升温到100度再加压到5MPA，保持5分钟后，继续升温到150度再加压到10MPA，保持5分钟后，升温到175度，并保持20分钟；
(4)将二氧化碳经过超临界流体注入及控制装置，在140度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到155度后保持5分钟，之后冷却到150度保持5分钟，再冷却到145度保持5分钟，继续冷却到140度保持5分钟后，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为20mm；放气过程进行到一半时，上外模打开，气体被完全放出。
从而，获得了具有上下取向状微孔结构的GF/PP微发泡制件，其最终产品的厚度为24毫米。
实施例4：
本实施例以聚对苯二甲酸乙二醇酯PET为基体，将PET材料放入到哈克转矩流变仪中在180～280温度下测试，在5rpm的低转速下时获知其平衡转矩值与温度的变化关系，其在235度时的平衡转矩值为11.4N*m，因此确定其适宜的熔融加工温度确定为235度。
以芳纶纤维(AF-1313)作为增强体，所得制品为AF/PET的微发泡板材，纤维含量为60wt％。
采用上述成型装置进行成型，其主要的制备过程包括：
(1)将芳纶纤维宽展后与PET在线预复合，形成AF/PET单向预浸带，其厚度为30微米，宽度为30毫米，长度为300毫米，其中芳纶纤维的含量控制在60wt％；
(2)将纤维预浸带均按照0度方向铺放101层后，预压形成纤维增强热塑性聚合物板材的预制件；预制件的厚度约为3mm。
(3)将预制件放置到安装在压力机上的模具内，抽真空后加热到90度并加压到1MPA，保持5分钟后，升温到140度再加压到5MPA，保持5分钟后，继续升温到190度再加压到10MPA，保持5分钟后，升温到235度，并保持20分钟；
(4)将二氧化碳经过超临界流体注入及控制装置，在200度的温度及15MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到210度后保持5分钟，之后冷却到200度保持5分钟，再冷却 到190度保持5分钟，继续冷却到180度保持5分钟后，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为9mm；放气过程进行到一半时，上外模打开，气体被完全放出。
从而，获得了具有上下取向状微孔结构的AF/PET微发泡制件，其最终产品的厚度为12毫米。
实施例5：
本实施例以聚萘二甲酸乙二醇酯PEN为基体，将PEN材料放入到哈克转矩流变仪中在220～320温度下测试，在5rpm的低转速下时获知其平衡转矩值与温度的变化关系，其在280度时的平衡转矩值为10.9N*m，因此确定其适宜的熔融加工温度确定为280度。
以碳纤维(CF，48K，T800)作为增强体，所得制品为CF/PEN的微发泡板材，纤维含量为50wt％。
采用上述成型装置进行成型，其主要的制备过程包括：
(1)将T800碳纤维宽展后与PEN在线预复合，形成T800/PEN单向预浸带，其厚度为50微米，宽度为300毫米，长度为300毫米，其中碳纤维的含量控制在50wt％；
(2)将纤维预浸带均按照0度和90度方向交替铺放101层后，预压形成纤维增强热塑性聚合物板材的预制件；预制件的厚度约为5mm。
(3)将预制件放置到安装在压力机上的模具内，抽真空后加热到90度并加压到1MPA，保持5分钟后，升温到160度再加压到5MPA，保持5分钟后，继续升温到230度再加压到10MPA，保持5分钟后，升温到280度，并保持20分钟；
(4)将氮气经过超临界流体注入及控制装置，在230度的温度及35MPA的压力下以每分钟50毫升的速度注入到模具内；
(5)将预制件稳定到250度后保持5分钟，之后冷却到240度保持5分钟，再冷却到230度保持5分钟，继续冷却到220度保持5分钟后，第一气体通道3和第二气体通道8打开并排出超临界流体，制品沿着上下方向开始膨胀，模具的内模芯受到作用力并在控制装置的作用下缓慢打开，其运动行程为10mm；放气过程进行到一半时，上外模打开，气体被完全放出。
从而，获得了具有上下取向状微孔结构的CF/PEN微发泡制件，其最终产品的厚度为15毫米。
将实施例3～5制备得到的连续纤维增强热塑性复合物微发泡制品进行性能测试，测试结果同实施例1、2相符。
综上，采用本发明上述实施例的成型方法，有效解决了连续纤维在发泡制品内部分 布的问题，纤维损伤率低，其层合与发泡在同一模具内完成，生产效率高，其制品的泡孔细赋，力学性能优异，可直接规模化应用。制造的连续纤维增强热塑性微发泡制品密度为普通纤维增强制品的0.01～1倍之间；该制品纤维层和泡孔层有微观层面的分层；最终制品中纤维的分布和其在预制件中的分布能够保持一致；泡孔层中的微孔密度在10 6cells/cm 3以上。

Claims (10)

  1. 一种连续纤维增强热塑性复合物微发泡制品，其特征在于：以热塑性聚合物为基体，连续纤维为增强相；所述微发泡制品具有单一取向的微孔结构，连续纤维呈平行排列。
  2. 一种连续纤维增强热塑性复合物微发泡制品的成型方法，其特征在于：包括以下步骤：
    (1)将经宽展后的连续纤维与热塑性聚合物进行复合，形成纤维增强热塑性聚合物薄层预浸带；
    (2)铺设预浸带形成预浸料，对预浸料进行预压处理，形成纤维增强热塑性聚合物预制件；
    (3)将预制件放置于模具中，真空状态下进行加热加压处理，向模具中注入超临界流体；
    (4)将预制件进行冷却，排出超临界流体，得到发泡制品。
  3. 根据权利要求2所述的连续纤维增强热塑性复合物微发泡制品的成型方法，其特征在于：步骤(1)中，预浸带的厚度为10～100μm，纤维的含量为10～80wt％。
  4. 根据权利要求2所述的连续纤维增强热塑性复合物微发泡制品的成型方法，其特征在于：步骤(2)中，相邻预浸带之间铺设有聚合物薄膜或片材，聚合物薄膜或片材的熔点不高于预浸带。
  5. 根据权利要求2所述的连续纤维增强热塑性复合物微发泡制品的成型方法，其特征在于：步骤(3)中，加热处理包括从室温分阶段加热至预浸料的加热温度峰值，加压处理至少包括三个阶段，三个阶段分别设置在1～2MPA、4～6MPA以及9～12MPA之间，每个阶段控制时间为5～60min；所述加热温度峰值T 加热＝T 测±10℃，T 测为将热塑性聚合物在流变试验条件下，5rpm的转速下平衡转矩值为8～12N*m时对应温度值。
  6. 根据权利要求2所述的连续纤维增强热塑性复合物微发泡制品的成型方法，其特征在于：步骤(3)中，向模具中注入预热的超临界流体，预热温度比预浸料加热温度峰值温度低30～50℃；注入超临界流体后，将预制件温度稳定在低于预浸料加热温度峰值温度20～40℃范围内，并保持5～20分钟。
  7. 根据权利要求2所述的连续纤维增强热塑性复合物微发泡制品的成型方法，其特征在于：步骤(4)中，预制件的冷却过程分2～5个阶段进行，每阶段降温幅度控制在5～10℃，每阶段温度保持时间为5～40min。
  8. 一种连续纤维增强热塑性复合物微发泡制品的成型装置，其特征在于：包括控制器、成型模具、压力装置和超临界流体注入装置，控制器与成型模具、超临界流体注入装置与压力装置相连；成型模具包括相适配的上模和下模、设于成型制品上方的内模芯，内模芯与压力装置相连，压力装置驱动内模芯在上下模之间运动；所述上模设有第一气 体通道，内模芯设有第二气体通道，第一气体通道与超临界流体注入装置相连。
  9. 根据权利要求8所述的连续纤维增强热塑性复合物微发泡制品的成型装置，其特征在于：成型制品置于下模中，上下模安装形成封闭空间；所述控制器控制模具的加热与冷却、气体通道的打开与关闭、以及压力装置和超临界流体注入装置的运行。
  10. 根据权利要求8所述的连续纤维增强热塑性复合物微发泡制品的成型装置，其特征在于：所述第二气体通道与成型制品相垂直。
PCT/CN2022/076286 2021-03-03 2022-02-15 一种连续纤维增强热塑性复合物微发泡制品及其成型方法和装置 WO2022183903A1 (zh)

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