A method and apparatus for the production of prepreg

Abstract

The application discloses a preparation method and device of prepreg, and the method comprises the following steps: placing resin in an extrusion mechanism, the extrusion mechanism heats the resin to melt or melt the resin, and the extrusion mechanism pressurizes the melted or molten resin to deliver the resin to a slit coating die; the molten or melted resin flows out through a first cavity, a second cavity and a guide outlet in sequence to form a resin film, and the resin film is combined with fibers, the infiltration is completed through roller pressing, and the prepreg is obtained. The application integrates the slit coating die in the device of the prepreg, coats the resin film on the base material of the yarn or fabric led out by the front-end mechanism, and then prepares the prepreg by roller pressing the resin film and the fibers. The preparation method does not need to prepare the resin film separately, the production steps are reduced, the thickness of the prepreg is uniform, and the quality stability is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of prepreg preparation, in particular to a prepreg preparation method and device. BACKGROUND

[0002] As a standardized intermediate material, the prepreg occupies an extremely important position in the field of composite material manufacturing due to its high precision control of resin content and simple operation.

[0003] In the prior art, the commonly used prepreg preparation method is mainly a two-step process of hot melting method, the process of which is: first, a resin is prepared by using a glue spreading machine, and then the resin is compounded with fibers. However, the prepreg prepared by this method has the disadvantages of large areal density fluctuation, poor stability, and inability to produce low areal density resin films. In addition, the hot melting method involves many process steps, and the produced resin not only occupies a certain space, but also has high requirements for the storage environment. SUMMARY

[0004] The purpose of the present application is to provide a prepreg preparation method and device, which aims to solve the problems of large areal density fluctuation, difficult control of product quality, and inability to produce low areal density resin films in the traditional hot melting method for preparing prepregs.

[0005] In a first aspect, the present application provides a prepreg preparation device, which comprises a slit coating die and an extrusion mechanism. The slit coating die comprises a first cavity in communication with the extrusion mechanism and a second cavity in communication with the first cavity. The slit coating die is provided with a guide outlet on the side close to the second cavity, and the guide outlet is in communication with the second cavity. The extrusion mechanism is used for placing and extruding resin, and the guide outlet is used for guiding out the molten or melted resin.

[0006] Preferably, the slit coating die is provided with at least one first through hole in communication with the first cavity on the side close to the first cavity. The slit coating die is further provided with a second through hole, one end of the second through hole is in communication with the first cavity, and the other end of the through hole is in communication with the second cavity.

[0007] The extrusion mechanism is connected with the first through hole through a conduit.

[0008] In a second aspect, the present application provides a prepreg preparation method, which is realized by the above-mentioned prepreg preparation device. The method comprises the following steps:

[0009] Resin is placed in the extrusion mechanism, and the extrusion mechanism is heated to melt or melt the resin. The extrusion mechanism pressurizes the resin and delivers the molten or melted resin into the slit coating die.

[0010] The molten or melted resin flows out through the first cavity, the second cavity and the outlet in sequence, forms a resin film, and is combined with the fiber, and the impregnation is completed by roller pressing to obtain the prepreg.

[0011] Preferably, the resin is a thermosetting resin, and the thermosetting resin at least includes one of unsaturated polyester resin, epoxy resin, phenolic resin, polyurethane resin, bismaleimide resin, polyimide resin and the like.

[0012] Preferably, the resin is a thermoplastic resin, and the thermoplastic resin at least includes one of polyethylene resin, polypropylene resin, polyamide resin, polycarbonate resin, polyphenylene sulfide resin, polyaryletherketone resin and the like.

[0013] Preferably, the resin film has an areal density of 2-200 g / m 2 .

[0014] Preferably, the fiber is at least one of inorganic fiber including carbon fiber, glass fiber, silicon carbide fiber, alumina fiber, ceramic fiber, ultrahigh molecular weight polyethylene fiber, ultrahigh molecular weight polypropylene fiber, polyamide fiber, polyacrylonitrile fiber, aramid fiber, poly-p-phenylene-benzobisoxazole fiber, polybenzimidazole fiber, polyimide fiber and the like, and organic fiber including cotton fiber, hemp fiber, bamboo fiber, cellulose fiber and the like, and the fiber has one of unidirectional fiber, woven fabric, knitted fabric, braided fabric and nonwoven fabric, and the fiber has an areal density of 3-400 g / m 2 .

[0015] Preferably, the prepreg has an areal density of 5-600 g / m 2 , and the prepreg has a resin content of 20wt%-50wt%, and the areal density has a variation of ±1%.

[0016] Preferably, the extrusion mechanism at least includes one of screw extruder, plunger pump and gear pump, and the extrusion mechanism has a heating temperature of room temperature-400℃, and the extrusion mechanism has an applied pressure of 0-20 MPa.

[0017] Preferably, the roller has a temperature of 50-400℃, and the roller has a pressure of 1-20 MPa.

[0018] Compared with the prior art, the present application has the following advantages:

[0019] 1. The present application places resin in the extrusion mechanism through a slot coating die. In actual production, the resin is melted or melted, passes through the first through hole through the pipe, and then flows into the slot coating die. When the resin flows into the first cavity, it is uniformly distributed in the first cavity. When the liquid value in the first cavity accumulates to a certain height, it is automatically flowed into the second cavity through the second through hole under the influence of its own gravity and extrusion pressure, and then flowed out from the guide outlet, forming a resin film, which is combined with the fiber to complete the preparation of the prepreg. The entire process does not require separate production of resin film, and does not require storage space and low temperature and humidity storage environment, which can effectively save storage costs.

[0020] 2. By combining liquid resin with fiber, the traditional "coating resin film and then combining with fiber" hot melt two-step method is replaced, so that the surface density variation of the prepreg is ±1%, which is much lower than the error of the hot melt two-step process, greatly improving the quality stability of the product.

[0021] 3. The surface density of the prepreg produced by the present application is 5-600g / m 2 , which can produce prepreg below 10g / m 2 , thereby meeting the production of ultra-thin prepreg.

[0022] 4. The production rate of the prepreg of the present application is 40-50m / min, which is much higher than the production speed of the hot melt two-step process, and has the advantage of high production efficiency.

[0023] Additional aspects and advantages of the present application will be partially given in the following description, partially apparent from the following description, or understood by the embodiments of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The structure schematic diagram of the slot coating die and the extrusion mechanism of the embodiment of the present application is shown;

[0025] Figure 2 The structure schematic diagram of a prepreg preparation device of the embodiment of the present application is shown;

[0026] Figure 3 Another structure schematic diagram of a prepreg preparation device of the embodiment of the present application is shown;

[0027] Figure 4 The flow chart of a prepreg preparation method of the embodiment of the present application is shown.

[0028] Explanation of symbols: 10 - slit coating die, 20 - extrusion mechanism, 40 - yarn collecting mechanism, 70 - winding mechanism, 80 - fabric unwinding mechanism, 90 - conduit, 101 - first cavity, 102 - second cavity, 103 - first through hole, 104 - second through hole, 105 - guide outlet, 301 - fixed plate, 302 - yarn spool, 501 - support member, 502 - yarn spreading roller, 601 - PE film unwinding device, 602 - release paper unwinding device, 603 - first roller, 604 - second roller. DETAILED DESCRIPTION

[0029] For the purposes of this application, reference will be made to the accompanying drawings in which several embodiments of the application are illustrated. The application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and fully convey the scope of the application to those skilled in the art.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] In this document, the term "°C" means "degrees Celsius"; the term "MPa" means: megapascal; the term "μm" means: micrometer; the term "g / m2" means: grams per square meter; the term "min" means: minute; the term "wt%" means: weight percent; the term "m / min" means: meters per minute. 2

[0032] In this document, all ranges are inclusive of the endpoints, and the combination of any sub-ranges within the given ranges. For example, the range of 1-5 specifically includes 1, 2, 3, 4, and 5, as well as sub-ranges such as 2-5, 3-5, 2-3, 2-4, 1-4, etc.

[0033] <First aspect>

[0034] As Figure 1 ​As shown, the embodiment of the present application provides a preparation device of prepreg, which comprises a slit coating die 10 and an extrusion mechanism 20. The slit coating die 10 comprises a first cavity 101 communicated with the extrusion mechanism 20 and a second cavity 102 communicated with the first cavity 101. The slit coating die 10 is provided with a guide outlet 105 on the side close to the second cavity 102, and the guide outlet 105 is communicated with the second cavity 102. The extrusion mechanism 20 is used for placing and extruding resin, and the guide outlet 105 is used for guiding the molten or melted resin.

[0035] In some embodiments, the slit coating die 10 is provided with at least one first through hole 103 communicated with the first cavity 101 on the side close to the first cavity 101. The slit coating die 10 is further provided with a second through hole 104, one end of which is communicated with the first cavity 101, and the other end of which is communicated with the second cavity 102. The extrusion mechanism 20 is connected with the first through hole 103 through a conduit 90. In actual production process, the resin is placed in the extrusion mechanism 20. The resin is melted or melted, and then flows into the slit coating die 10 through the first through hole 103 and the conduit 90. When the resin flows into the first cavity 101, it is uniformly distributed in the first cavity 101. When the liquid value in the first cavity 101 accumulates to a certain height, it automatically flows into the second cavity 102 through the second through hole 104 under the influence of its own gravity and extrusion pressure, and then flows out of the guide outlet 105. Then, the resin is combined with the fiber to complete the preparation of the prepreg.

[0036] It should be pointed out that the guide outlet 105 penetrates through the bottom of the slit coating die 10 along the transverse direction. The fiber is combined with the liquid resin coming out of the guide outlet 105 along the transverse direction, which can further improve the prepreg effect.

[0037] In some embodiments, the extrusion mechanism 20 is one of a plunger pump, a gear pump and a screw extruder.

[0038] In some embodiments, as shown, Figure 2 In addition to the extrusion mechanism 20 and the slit coating die 10, the preparation device of the prepreg further comprises a creel mechanism, a yarn collecting mechanism 40, a yarn spreading mechanism, a prepreg mechanism and a winding mechanism 70.

[0039] The creel mechanism comprises a fixed plate 301 and a yarn shaft 302 arranged on the fixed plate 301, and the yarn shaft 302 is used for placing a yarn roll. The yarn spreading mechanism comprises a support 501 and a plurality of yarn spreading rollers 502 arranged on the support 501. The fiber collecting mechanism 40 is a fiber collecting plate provided with a plurality of through holes. The prepreg mechanism comprises a PE film unwinding device 601, a release paper unwinding device 602, and two first rollers 603 and two second rollers 604 located on both sides of the yarn. The first roller 603 is used for pressing the liquid resin and the fiber yarn. The PE film unwinding device 601 is used for placing the PE film. The release paper unwinding device 602 is used for placing the release paper. The second roller 604 is used for pressing the PE film and the fiber yarn with prepreg resin. The winding mechanism 70 is used for winding the prepared prepreg.

[0040] In the actual production process, the yarn in the yarn roll is transported to the fiber collecting mechanism 40 through the creel mechanism, and is transported to the yarn spreading mechanism along the same horizontal plane. The liquid resin output by the extrusion mechanism 20 and the die 10 is transported to the spread yarn, and is pressed and prepregged by the upper and lower first rollers. Then, the upper surface of the fiber yarn with prepreg resin is combined with the transported PE film, and the lower surface is combined with the transported release paper, which are pressed by the upper and lower second rollers, so that the prepreg is obtained. The prepreg is transported to the winding mechanism 70, so that the winding of the prepreg is completed.

[0041] In some embodiments, as shown in Figure 3 , the prepreg preparation device further comprises a fabric unwinding mechanism 80, a prepreg mechanism, and a winding mechanism 70 in addition to the extrusion mechanism 20 and the slot die 10.

[0042] The fabric unwinding mechanism 80 is used for placing the fabric. The prepreg mechanism comprises a PE film unwinding device 601, a release paper unwinding device 602, and two first rollers 603 and two second rollers 604 located on both sides of the yarn. The first roller 603 is used for pressing the liquid resin and the fiber yarn. The PE film unwinding device 601 is used for placing the PE film. The release paper unwinding device 602 is used for placing the release paper. The second roller 604 is used for pressing the PE film and the fiber yarn with prepreg resin. The winding mechanism 70 is used for winding the prepared prepreg.

[0043] In the actual production process, the fabric is continuously transported by the fabric unwinding device. The liquid resin output by the extrusion mechanism 20 and the die 10 is transported to the fabric, and is pressed and prepregged by the upper and lower first rollers. Then, the upper surface of the fiber yarn with prepreg resin is combined with the transported PE film, and the lower surface is combined with the transported release paper, which are pressed by the upper and lower second rollers, so that the prepreg is obtained. The prepreg is transported to the winding mechanism 70, so that the winding of the prepreg is completed.

[0044] In summary, according to the above-mentioned device for preparing a prepreg, the resin is placed in the extrusion mechanism through the slot coating die. In the actual production process, the resin is melted or melted, and then flows into the slot coating die through the first through hole. When the resin flows into the first cavity, it is uniformly distributed in the first cavity. When the liquid value in the first cavity accumulates to a certain height, it is automatically flowed into the second cavity through the second through hole under the influence of its own gravity and extrusion pressure, and then flowed out from the guide outlet. Then it is combined with the fiber to complete the preparation of the prepreg. The whole process does not need to produce resin film separately, and does not need to provide resin storage space and low temperature and humidity storage environment, which can effectively save storage cost. In addition, by realizing the combination of liquid resin and fiber, the traditional "coating resin film and then compounding with fiber" hot melting two-step method is replaced, so that the surface density variation of the prepreg is ±1%, which is much lower than the error of the hot melting two-step process, greatly improving the quality stability of the product.

[0045] As shown in Figure 4 , the embodiment of the present application provides a method for preparing a prepreg, which comprises steps S101 to S102, wherein:

[0046] Step S101: placing resin in an extrusion mechanism, heating the extrusion mechanism to melt or melt the resin, and pressurizing the resin in the extrusion mechanism to deliver the melted or melted resin to a slot coating die;

[0047] Step S102: the melted or melted resin flows out through the first cavity, the second cavity and the guide outlet in sequence, forms a resin film, and is combined with the fiber. Through the roller pressing, the infiltration is completed, and the prepreg is obtained.

[0048] In some embodiments, the resin can be a thermoplastic resin or a thermosetting resin, wherein the thermosetting resin at least includes one of unsaturated polyester resin, epoxy resin, phenolic resin, polyurethane resin, bismaleimide resin, polyimide resin and other thermosetting resins, and the thermoplastic resin at least includes one of polyethylene resin, polypropylene resin, polyamide resin, polycarbonate resin, polyphenylene sulfide resin, polyaryletherketone resin and other thermoplastic resins.

[0049] In some embodiments, the surface density of the resin film is 2-200 g / m 2 That is, by melting or melting the resin and then pre-impregnating, it can be suitable for pre-impregnation of very low surface density resin, and has wide industrial range and strong applicability. For example, the surface density of the resin can be 2 g / m 2 , 10 g / m 2 , 50 g / m 2 , 100 g / m 2 , 150 g / m 2 , 200 g / m2 and so on.

[0050] In some embodiments, the material of the fiber at least includes one of carbon fiber, glass fiber, silicon carbide fiber, alumina fiber, ceramic fiber, inorganic fiber, ultra-high molecular weight polyethylene fiber, ultra-high molecular weight polypropylene fiber, polyamide fiber, polyacrylonitrile fiber, aramid fiber, poly-p-phenylene-benzobisoxazole fiber, polybenzimidazole fiber, polyimide fiber, organic fiber, cotton fiber, hemp fiber, bamboo fiber, cellulose fiber, and plant fiber, that is, the fiber can be made of a single material of carbon fiber, glass fiber, silicon carbide fiber, alumina fiber, ceramic fiber, inorganic fiber, ultra-high molecular weight polyethylene fiber, ultra-high molecular weight polypropylene fiber, polyamide fiber, polyacrylonitrile fiber, aramid fiber, poly-p-phenylene-benzobisoxazole fiber, polybenzimidazole fiber, polyimide fiber, organic fiber, cotton fiber, hemp fiber, bamboo fiber, cellulose fiber, and plant fiber, or made of multiple materials of carbon fiber, glass fiber, silicon carbide fiber, alumina fiber, ceramic fiber, inorganic fiber, ultra-high molecular weight polyethylene fiber, ultra-high molecular weight polypropylene fiber, polyamide fiber, polyacrylonitrile fiber, aramid fiber, poly-p-phenylene-benzobisoxazole fiber, polybenzimidazole fiber, polyimide fiber, organic fiber, cotton fiber, hemp fiber, bamboo fiber, cellulose fiber, and plant fiber, the fiber is one of unidirectional fiber, woven fabric, knitted fabric, braided fabric, and non-woven fabric, that is, the fiber is in a single form of unidirectional fiber, woven fabric, knitted fabric, braided fabric, and non-woven fabric; the areal density of the fiber is 3-400 g / m 2 , for example, the areal density of the fiber can be 3 g / m 2 , 5 g / m 2 , 10 g / m 2 , 50 g / m 2 , 100 g / m 2 , 150 g / m 2 , 200 g / m 2 , 300 g / m 2 , 400 g / m 2 and so on.

[0051] In some embodiments, the areal density of the prepreg is 5-600 g / m 2 , for example, the areal density of the obtained prepreg can be 5 g / m 2 , 10 g / m 2 , 50 g / m 2 , 100 g / m 2 , 150 g / m 2 , 200 g / m 2 , 300 g / m 2 , 400 g / m 2 , 500 g / m 2, 600 g / m 2 ±1%, which is much lower than the error of the hot-melt two-step process, indicating that the product quality is stable and high; in addition, the resin content of the prepreg is 20wt%-50wt%, for example, the resin content of the prepreg can be 20wt%, 30wt%, 40wt%, 50wt%, etc.

[0052] In some embodiments, the heating temperature of the extrusion mechanism is room temperature-400°C, so that the resin is completely melted or molten, if the heating temperature is too low, the resin will not be completely melted or molten, or even not melted or molten, and if the heating temperature is too high, it will cause energy waste, for example, the heating temperature of the extrusion mechanism can be 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, etc. The applied pressure of the extrusion mechanism is 0-20MPa, for example, the applied pressure can be 1MPa, 5MPa, 10MPa, 15MPa, 20MPa, etc.

[0053] In some embodiments, the temperature of the roller is 50-400°C, that is, the temperature of the first roller and the second roller is 50-400°C, for example, the temperature of the roller can be 50°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, so that the resin can also maintain a molten or melted state when combined with the fiber. The pressure of the roller is 1-20MPa, that is, the pressure of the first roller and the second roller is 1-20MPa, for example, the pressure of the roller can be 1MPa, 5MPa, 10MPa, 15MPa, 20MPa, etc.

[0054] In some embodiments, the production rate of the prepreg using the method of the present application is 40-50m / min, which is much higher than the production speed of the hot-melt two-step process, and has the advantage of high production efficiency.

[0055] Example 1

[0056] 5kg of epoxy resin was placed in a plunger pump, the plunger pump heating temperature was kept at 80°C, and the pressure was 3MPa, the melted epoxy resin was introduced into the slit coating die, and then flowed out through the first cavity, the second cavity, and the outlet, to coat the surface of the glass fiber yarn with a surface density of 97.5g / m 2 The first roller and the second roller were continuously pressed, the pressure of the first roller and the second roller was 1MPa, and the temperature was 80°C, to prepare a glass fiber / epoxy prepreg with a surface density of 150±1.3g / m 2 The production speed was 40m / min, and the resin content in the prepreg was 35wt%.

[0057] Example 2

[0058] 2kg of polypropylene powder was placed in a screw extruder, the screw heating temperature was kept at 210℃, the pressure was kept at 10MPa, the melted polypropylene resin was introduced into a slit coating die, and then flowed out through the first cavity, the second cavity and the guide outlet in sequence, so as to be coated on the surface of 3g / m 2 of carbon fiber yarn (T300-1K), and then continuously pressed by the first roller and the second roller, the pressure of the first roller and the second roller was 10MPa, and the temperature was 210℃, so as to prepare an ultra-thin prepreg with a surface density of 5g / m 2 , the production speed was 50m / min, and the resin content in the prepreg was 40wt%.

[0059] Example 3

[0060] 2kg of polypropylene powder was placed in a screw extruder, the screw heating temperature was kept at 210℃, the pressure was kept at 10MPa, the melted polypropylene resin was introduced into a slit coating die, and then flowed out through the first cavity, the second cavity and the guide outlet in sequence, so as to be coated on the surface of 200g / m 2 of aramid plain fabric, and then continuously pressed by the first roller and the second roller, the pressure of the first roller and the second roller was 10MPa, and the temperature was 210℃, so as to prepare an aramid plain fabric reinforced polypropylene prepreg with a surface density of 300±2g / m 2 , the production speed was 45m / min, and the resin content in the prepreg was 33wt%.

[0061] Example 4

[0062] 2kg of epoxy resin was placed in a gear pump, the gear pump temperature was kept at 70℃, the pressure was kept at 11.5MPa, the melted epoxy resin was introduced into a slit coating die, and then flowed out through the first cavity, the second cavity and the guide outlet in sequence, so as to be coated on the surface of 300g / m 2 of carbon fiber yarn (T700SC-24K), and then continuously pressed by the first roller and the second roller, the pressure of the first roller and the second roller was 10.5MPa, and the temperature was 90℃, so as to prepare a carbon fiber / epoxy prepreg with a surface density of 400±3g / m 2 , the production speed was 45m / min, and the resin content in the prepreg was 25wt%.

[0063] Example 5

[0064] 2kg of polyether ether ketone plastic particles was placed in a screw extruder, the screw heating temperature was kept at 400℃, the pressure was kept at 15MPa, the melted polyether ether ketone resin was introduced into a slit coating die, and then flowed out through the first cavity, the second cavity and the guide outlet in sequence, so as to be coated on the surface of 20g / m2 of 30±0.25g / m 2 , the resin content in the prepreg is 33wt%.

[0065] Comparative Example 1

[0066] A carbon fiber (T800H-6K) / epoxy prepreg with a surface density of 30g / m 2 was prepared by a two-step process of hot melt method. 2kg of epoxy resin was placed in a trough, the roller temperature was kept at 80℃, the epoxy resin was melted, introduced into a resin coating machine, and formed into a resin film by three-roller pressing, then the resin film was placed in a compound machine to be compounded with carbon fiber, to obtain a carbon fiber / epoxy prepreg with a surface density of 30±4g / m 2 , the resin content in the prepreg is 33wt%. A large amount of release paper and PE film was consumed in the whole process.

[0067] Comparative Example 2

[0068] 2kg of epoxy resin was placed in a trough, the roller temperature was kept at 80℃, the epoxy resin was melted, introduced into a resin coating machine, and formed into a resin film with a surface density of 5g / m 2 , then the resin film was placed in a compound machine to be compounded with carbon fiber (T300-1K), to obtain a carbon fiber / epoxy prepreg with a surface density of 25±2g / m 2 , the resin content in the prepreg is 40wt%. It was found that the limit surface density of resin film prepared by three-roller was 5g / m 2 , and it was impossible to prepare ultra-thin prepreg (surface density less than 10g / m 2 ) by double film covering method.

[0069] Comparative Example 3

[0070] 2kg of epoxy resin was placed in a gear pump, the gear pump temperature was kept at 40℃ and the pressure was 20MPa, the melted epoxy resin was introduced into a slit coating die, and flowed out through the first cavity, the second cavity and the outlet in turn, to be coated on carbon fiber yarn (T700SC-24K) with a surface density of 300g / m 2 , then the carbon fiber yarn was continuously pressed by the first roller and the second roller, the pressure of the first roller and the second roller was 10.5MPa and the temperature was 90℃, to obtain a carbon fiber / epoxy prepreg with a surface density of 400±5g / m 2The carbon fiber / epoxy prepreg is produced at a speed of 5 m / min, and the resin content in the prepreg is 25 wt%.

[0071] As can be seen from Comparative Example 1, the prepreg is prepared by using the hot-melt two-step process. On the one hand, the preparation of the resin film consumes materials such as release paper and PE film. On the other hand, the resin film needs space and a low-temperature and low-humidity environment for storage before being combined with the fibers, which consumes a large amount of storage costs. The slit coating method for manufacturing the prepreg provided by the present application can avoid the separate manufacture of the resin film and save storage costs. In addition, as can be seen from Comparative Example 2 and Comparative Example 3, the present application has great advantages in manufacturing ultra-thin prepreg and in controlling the stability of the surface density of the prepreg.

[0072] As can be seen from Example 4 and Comparative Example 3, there is a suitable parameter range for the slit coating process. The resin extrusion mechanism in Example 4 and Comparative Example 3 is a gear pump. The heating temperature of the gear pump is different. The heating temperature in Example 4 is 70℃. The epoxy resin has good fluidity at 70℃, so it is easy to achieve good impregnation of the fibers, and the production speed can reach 45 m / min. In Comparative Example 3, the heating temperature of the gear pump is only 40℃. The viscosity of the epoxy resin at 40℃ is still very large, and the fluidity is poor. Even if the resin extrusion pressure is increased to 20 MPa, the production speed of the prepreg cannot be accelerated. The production speed of the prepreg in Comparative Example 3 is only 5 m / min, which is low and cannot meet the requirements of industrial production.

[0073] The above-described examples only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent of the present application. It should be pointed out that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A method for producing a prepreg, by a prepreg production apparatus, characterized by, The method comprises: Placing the resin in an extrusion mechanism, heating the extrusion mechanism to melt or melt the resin, the extrusion mechanism pressurizes the resin, and the melted or melted resin is transported to a slit coating die; The melted or melted resin flows out of the first cavity, the second cavity and the guide outlet in turn, forms a resin film, and is combined with the fiber, is pressed by the roller, completes the infiltration, and obtains the prepreg; The areal density of the prepreg is 5-600 g / m2, the areal density variation range is ±1%, and the resin content of the prepreg is 20wt%-50wt%; The preparation device of the prepreg comprises a slit coating die and an extrusion mechanism, the slit coating die comprises a first cavity communicated with the extrusion mechanism and a second cavity communicated with the first cavity, the slit coating die is provided with a guide outlet on the side close to the second cavity, the guide outlet is communicated with the second cavity, the extrusion mechanism is used for placing and extruding the resin, and the guide outlet is used for guiding out the melted or melted resin; The slit coating die is provided with at least one first through hole communicated with the first cavity on the side close to the first cavity, and the slit coating die is further provided with a second through hole, one end of the second through hole is communicated with the first cavity, and the other end of the through hole is communicated with the second cavity; The extrusion mechanism is connected with the first through hole through a conduit.

2. The method of making a prepreg according to claim 1, wherein, The resin is a thermosetting resin, and the thermosetting resin at least comprises one of unsaturated polyester resin, epoxy resin, phenolic resin, polyurethane resin, bismaleimide resin and polyimide resin thermosetting resin.

3. The method of making a prepreg according to claim 1, wherein, The resin is a thermoplastic resin, and the thermoplastic resin at least comprises one of polyethylene resin, polypropylene resin, polyamide resin, polycarbonate resin, polyphenylene sulfide resin and polyaryletherketone resin thermoplastic resin.

4. The method of making a prepreg according to claim 1, wherein, The resin film has a surface density of 2 to 200 g / m 2 .

5. The method of making a prepreg according to claim 1, wherein, The material of the fiber at least includes one of carbon fiber, glass fiber, silicon carbide fiber, alumina fiber, ceramic fiber inorganic fiber, ultra-high molecular weight polyethylene fiber, ultra-high molecular weight polypropylene fiber, polyamide fiber, polyacrylonitrile fiber, aramid fiber, poly-p-phenylene-benzobisoxazole fiber, polybenzimidazole fiber, polyimide fiber organic fiber, cotton fiber, hemp fiber, bamboo fiber, cellulose fiber plant fiber, the fiber form is one of unidirectional fiber, woven fabric, knitted fabric, braided fabric, non-woven fabric, the areal density of the fiber is 3~400 g / m 2 .

6. The method of making a prepreg according to claim 1, wherein, The extrusion mechanism at least comprises one of a screw extruder, a plunger pump and a gear pump, the heating temperature of the extrusion mechanism is room temperature-400 DEG C, and the applied pressure of the extrusion mechanism is 0-20 MPa.

7. The method of making a prepreg according to claim 1, wherein, The temperature of the roller is 50-400 DEG C, and the pressure of the roller is 1-20 MPa.

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