Thermoplastic prepreg preparation system and method based on powder suspension methodTechnical Field
The invention relates to the technical field of thermoplastic composite materials, in particular to a preparation system and a preparation method of a thermoplastic prepreg based on a powder suspension method.
Background
With the progress of the current material science field, the stability and quality control of the prepreg preparation process are effectively guaranteed, and various preparation process technologies are greatly developed. With the continuous optimization of the resin matrix and the reinforced fiber performance, the research and development of the prepreg are greatly promoted. The prepreg is a composition of a ribbon-like or sheet-like resin matrix and a reinforcing body, which is prepared by impregnating reinforcing fibers or fabrics with a resin matrix under strictly controlled conditions, and is an intermediate material for producing a composite material. The manufacturing process technology is becoming more and more exquisite, the application field is also being widened, and the application of the technology has become a key factor for promoting the innovation of high-performance composite materials. The resin-based prepreg is widely applied to the fields of national defense and military industry, aerospace, construction engineering, leisure competitive sports and the like by virtue of the characteristics of small density, high strength-weight ratio, high design flexibility, excellent electrical performance, corrosion resistance and the like. There are two categories, thermosetting resin-based prepregs and thermoplastic resin-based prepregs, depending on the nature of the resin matrix in the reinforced resin-based prepreg. Thermosetting resin-based prepregs have some inherent disadvantages such as brittleness, large thermal expansion coefficient, difficult processing, high cost, difficult recovery, etc. because they undergo intermolecular crosslinking reaction during curing to form rigid refractory melt solids, and their application fields are gradually replaced by thermoplastic resin-based prepregs. The thermoplastic resin-based prepreg and the thermosetting resin-based prepreg have obvious molecular structure differences, and have the advantages of (1) good mechanical property, toughness, high fatigue strength, better damage tolerance and low-speed impact damage resistance, (2) good processing manufacturability, capability of being processed into various parts with complex shapes and precise dimensions, high production efficiency and low cost, and (3) less waste generated in the use process, repeated use and environmental friendliness. Therefore, thermoplastic resin-based prepregs have become ideal choices in many fields in recent years, so that the thermoplastic resin-based prepregs have wide application prospects in future development, and are widely applied and popularized along with continuous progress of technology and improvement of environmental protection requirements of people.
The method for preparing the thermoplastic prepreg by adopting the powder suspension generally uses water as a solvent, has low cost and no pollution, and the suspension ensures that the resin powder is uniformly distributed on the surface of the reinforced fiber, thereby being beneficial to reducing the processing difficulty of the prepreg and improving the molding quality.
In order to obtain good interfacial properties of thermoplastic composite materials, it is highly desirable to provide a process and a preparation apparatus that are easy to operate and have high efficiency.
Disclosure of Invention
In view of the above, the technical problem to be solved by the present invention is to provide a preparation system and a method for preparing a thermoplastic prepreg, wherein the thermoplastic prepreg prepared by the present invention can obtain better interfacial properties and mechanical properties.
The invention provides a preparation system and a preparation method of a thermoplastic prepreg based on a powder suspension method, wherein the preparation system comprises the following steps:
1) After the continuous fibers are pulled out from the creel, carrying out yarn discharging and yarn spreading treatment on the continuous fibers;
2) Soaking the continuous fibers after yarn spreading in the step 1) into a resin tank to enable thermoplastic resin to adhere to the surfaces of the continuous fibers;
3) Drawing the continuous fibers adhered with the thermoplastic resin in the step 2) into an oven, removing water and preheating;
4) Heating the preheated continuous fibers in the step 3) by a high-temperature constant-pressure template to make the thermoplastic resin adhered to the surfaces of the continuous fibers in a molten state;
5) Impregnating the thermoplastic resin heated and melted in the step 4), calendaring, leveling, cooling and shaping;
6) And (3) cutting edges and rolling the shaped prepreg in the step (5).
Preferably, in step 1), ultra-thin ultra-wide filament spreading of the continuous fibers is performed, the surface density and the width are performed, the angle between the yarn discharging combs is adjusted, gaps among yarn bundles after yarn discharging are controlled, and the optimal effect of yarn spreading is promoted. The yarn spreading mechanism is positioned behind the yarn discharging mechanism and in front of the second traction mechanism, and the yarn spreading mechanism performs ultra-thin ultra-wide yarn spreading on the continuous fibers.
Preferably, the yarn spreading mechanism is characterized in that the continuous fibers are uniformly spread into 350mm by the display mechanism, and the yarn spreading mechanism consists of a tension roller bracket, a static roller bracket, a guide shaft, a servo motor, a screw rod, an infrared lamp and the like.
Preferably, in the step 2), thermoplastic resin and deionized water are mixed according to the proportion of 1:3, an emulsifying agent, a dispersing agent and the like are added to prepare suspension, the suspension is placed into a resin tank, the resin tank is provided with a concentration automatic adjusting system and a concentration automatic controlling system, two groups of pressing rollers and one group of carrier rollers are arranged in the tank, and the suspension is continuously oscillated by ultrasonic waves to prevent resin from aggregating and precipitating.
Preferably, the method is characterized in that the continuous fibers are infiltrated by a resin tank, so that the thickness of the prepreg is controlled to be between 0.13 and 0.2 mm.
Preferably, in the step 3), the fibers fully suspended in the suspension pass through an oven at a speed of 3-5 m/min to evaporate water and preheat resin, the whole oven is heated by a quartz lamp and is divided into two parts, wherein the heating temperature of the first part is 150-200 ℃ for removing water in the continuous fibers, and the heating temperature of the second part is 250-300 ℃ for preheating the resin adhered on the continuous fibers. The oven is composed of a plurality of groups of supporting rollers, an exhaust fan, heat insulation cotton and the like.
Preferably, in step 4), the preheated resin is introduced into the high-temperature constant-pressure die plate under the action of traction force to be in a molten state. The high-temperature constant-pressure template is heated by electromagnetic heating, so that the temperature is kept between 380 ℃ and 400 ℃.
Preferably, in step 5), the heated and melted thermoplastic resin is subjected to impregnation and calendaring and prepreg leveling under the action of 3 calendaring rollers with different temperatures. The calendaring mechanism consists of 3 calendaring rollers, hot oil is introduced into the rollers, and the surface temperatures of the 3 calendaring rollers are 280 ℃, 200 ℃ and 120 ℃ respectively.
Preferably, in step 6), the prepreg shaped in step 5) is subjected to edge cutting and winding. The prepreg is cut under the action of the air pressure slitting knife and the bed knife, waste materials are recovered under the action of the waste material winding machine for subsequent utilization, and finished prepreg is wound under the action of the finished product winding machine.
Preferably, the preparation system and the preparation method of the thermoplastic prepreg based on the powder suspension method comprise a creel, a yarn discharging mechanism, a traction mechanism, a yarn spreading mechanism, a resin tank, an oven, a high-temperature constant-pressure template, a calendaring leveling mechanism and a trimming and winding mechanism.
The equipment mainly comprises the following components:
1) The creel comprises a yarn guide roller, a carrier roller, a fiber yarn spindle damping mechanism, a yarn carrier Ma Lun and the like;
2) The yarn discharging mechanism comprises a tensioning roller, yarn discharging comb teeth, a tensioning mechanism, a precise adjusting table and the like;
3) The traction mechanism (3 groups of positions are respectively a yarn spreading mechanism inlet, a yarn spreading mechanism outlet and an oven inlet, the traction speed range is about 0-5m/min, and the speed is adjustable and controllable. ) The device comprises a rubber coating compression roller, a power steel roller, a 2.2KW gear motor, a pressure regulating cylinder, a gear set and the like;
4) The yarn spreading mechanism comprises a tensioning roller, a heat insulation layer, an infrared lamp, a static roller, a tensioning bracket, a guide shaft, a tension sensor, a servo motor, a screw rod and the like;
5) The resin tank comprises a lifting roller, a rubber extruding roller, an electric heating pipe, a radar liquid level device, an ultrasonic oscillation device, a control system, a concentration automatic adjusting system and the like;
6) An oven, which comprises an exhaust fan, an infrared heating lamp, a supporting roller, a position adjusting mechanism, heat insulation cotton and the like;
7) A high-temperature constant-pressure template, which comprises an electromagnetic heating module, a frequency converter (the frequency is 12KHz-22 KHz), a mould which is opened and closed up and down, and the like;
8) Leveling and calendaring mechanism, which comprises calendaring rollers (3 rollers with internal hot oil introduced, temperature adjustable and controllable, diameter of the rollers)) The self-aligning roller bearing, the water cooling system, the oil heating device and the like;
9) The trimming and winding mechanism consists of a fixed-distance regulating ruler, an air pressure dividing knife, a bed knife, a servo motor, a waste material winding machine, a force control motor, a clutch winding drum and the like.
The continuous fiber enters a yarn discharging mechanism from a yarn frame, continuous fiber is subjected to yarn dividing treatment under the combined action of a tension roller and yarn discharging comb teeth, the continuous fiber enters a yarn spreading mechanism under the action of a No. 1 tractor to be subjected to continuous fiber yarn spreading treatment, the continuous fiber enters a resin tank under the action of a No. 2 tractor to be subjected to thermoplastic resin infiltration, the infiltrated continuous fiber enters an oven under the action of a No. 3 tractor to be subjected to moisture removal and thermoplastic resin preheating treatment, the preheated thermoplastic resin enters a high-temperature constant-pressure template under the action of the continuous fiber to be heated, the resin of the preheated thermoplastic resin reaches a molten state, the continuous fiber with the molten resin enters a leveling and calendaring mechanism immediately after coming out of the high-temperature constant-pressure template, the thermoplastic resin is impregnated and cooled and crystallized under the action of the 3 calendaring rollers, and the prepreg after the resin cooling crystallization is subjected to constant-edge cutting and finished product and waste rolling under the action of a slitting and rolling mechanism.
Compared with the prior art, the invention has the beneficial effects that the thermoplastic resin is difficult to dissolve in water, so that the water is used as a solvent, and the resin is prevented from aggregation and precipitation by adding the emulsifying agent, the dispersing agent and the like. Therefore, the invention adopts a suspension mode to resin by a powder suspension method, and a plurality of groups of movable lifting rollers are added in a resin tank to ensure that the resin is uniformly adhered to the surface of the fiber, and the consistency of the thickness and the stability of the quality of the prepreg are ensured under the action of a glue extrusion roller. The resin is uniformly dispersed into the suspension in a particle state, so that the resin can better permeate into the fiber, the uniform and sufficient resin infiltration of the fiber is realized, the waste caused by excessive infiltration is effectively avoided, and the phenomena of dripping and splashing of the resin in the infiltration process are reduced.
Drawings
FIG. 1 is a top view of a continuous fiber add-drop thermoplastic prepreg unidirectional tape production line.
Fig. 2 is a front view of a continuous fiber add-drop thermoplastic prepreg unidirectional tape production line.
FIG. 3 is a cross-sectional view of a continuous fiber add-drop thermoplastic prepreg unidirectional tape production line.
FIG. 4 is a side view of a continuous fiber add-drop thermoplastic prepreg unidirectional tape production line.
Fig. 5 is a left side view of a continuous fiber add-drop thermoplastic prepreg unidirectional tape production line.
Fig. 6 is an enlarged schematic view at a of fig. 3.
Fig. 7 is an enlarged schematic view at B of fig. 3.
Fig. 8 is an enlarged schematic view at C of fig. 3.
The drawing comprises a drawing number 1, a creel, a yarn arranging mechanism 2, a traction mechanism 3, a yarn expanding mechanism 4, a resin tank 5, a 6, an oven, a 7, a high-temperature constant pressure template 8, a leveling calendaring mechanism 9, a trimming and rolling mechanism 10, a tensioning mechanism 11, a yarn arranging comb tooth 12, a tensioning roller 13, a precision adjusting table (with a graduated scale), a 14, a pressure adjusting cylinder 15, a rubber coating compression roller 16, a power steel roller 17, a gear set 18, a calendaring roller 19 and a self-aligning roller bearing.
Detailed Description
In order to further understand the technical means, features and specific objects and functions achieved by the present invention, the present invention will be described in further detail with reference to the accompanying drawings and detailed description.
Referring to fig. 1-8, the continuous fiber reinforced thermoplastic prepreg production line mainly comprises a creel, a yarn discharging mechanism, a traction mechanism, a yarn spreading mechanism, a resin tank, an oven, a high-temperature constant-pressure template, a leveling calendaring mechanism, a trimming and rolling mechanism.
In the production process of the prepreg, the width of the prepreg is firstly determined, and the number of the spindle is calculated according to the width of the prepreg and a formula, wherein the specific formula is as follows:
where n is the bundle number, w is the prescribed spread, h is the prepreg thickness, η is the fiber volume fraction, and d is the fiber strand diameter.
After the number of continuous fiber spindles is determined, continuous fibers release continuous fiber precursors from a creel, are arranged into a strip shape through a yarn guide roller of the creel, enter a yarn discharging mechanism 2, and are subjected to actual position adjustment through a tensioning adjustment mechanism 10 according to actual conditions, so that the continuous fibers can be better discharged, the angle between yarn discharging comb teeth 11 is adjusted through a precise adjustment table 13 according to the surface density and width requirements of finished prepreg, gaps between yarn bundles after yarn discharging are controlled, and the best effect of yarn spreading is promoted.
After the continuous fiber tows are discharged, the relation between the actual positions of the rubber coating compression roller 15 and the power steel roller 16 is controlled by adjusting the pressure adjusting cylinder 14 of the traction mechanism 3, the rotating speed of the servo motor in the traction mechanism 3 is controlled to reduce the speed of the gear group 17 of the continuous fiber, so that the continuous fiber obtains the actual traction speed, the continuous fiber enters the continuous fiber tows from the inlet of the yarn spreading mechanism 4 for spreading under the traction action of the first traction mechanism 3, the screw rod is driven by adjusting the servo motor of the yarn spreading mechanism 4 to control the actual position of the tensioning bracket, the corresponding displacement change between the tensioning roller and the static roller is realized, the continuous fiber tows are uniformly heated in the manners of embedding the heating rod between the tensioning roller and the static roller and heating by an infrared lamp in the yarn spreading mechanism, the continuous fiber tows become smoother and easier to spread, and the sizing agent on the upper part of the continuous fiber tows is removed by the heating manner, so that the continuous fiber tows are easier to be infiltrated with thermoplastic resin.
The continuous fiber tows after yarn spreading are pulled into a resin tank 5 from an outlet of a yarn spreading mechanism 4 by a second traction mechanism 3, the continuous fiber tows after yarn spreading are fully soaked into suspension by the combined action of a plurality of groups of lifting rollers in the resin tank 5, thermoplastic resin is uniformly adhered to the surface of the continuous fiber by the combined auxiliary action of ultrasonic vibration and an electric heating pipe, the continuous fiber after resin soaking passes through a pair of rubber extruding rollers with adjustable intervals on the resin tank 5 under the action of a 3 rd traction mechanism 3, the relative positions of the rubber extruding rollers can be kept stable and the extrusion force can be synchronously adjusted, so that the resin soaking amount is adjusted, redundant resin is continuously extruded along with the traction of the traction mechanism 3, the resin is uniformly adhered to the surface of the continuous fiber, the resin tank 5 is integrally formed by welding stainless steel, and two liquid draining valve ports are arranged at the bottom for discharging the suspension.
The continuous fiber tows are precisely and stably guided into the traction mechanism 3 for traction through a finely designed rubber extrusion roller device. In the process, the continuity and the integrity of the continuous fiber tows are ensured, and the uniform distribution of the resin infiltrated on the surfaces of the tows is ensured without any flaws. Under the accurate traction of the traction mechanism 3, the continuous fiber tows slowly enter the oven 6 according to the preset speed and direction. The front half part of the oven 6 is designed to be ingenious, and the built-in infrared heating lamps and the multiple groups of supporting rollers cooperate with each other to form an efficient water evaporation system. The infrared heating lamp can rapidly and uniformly raise the temperature in the oven through a unique heating mode, and provides sufficient energy for water evaporation in the continuous fiber tows. The supporting roller plays a role in expanding the contact area of the continuous fiber tows and the heated air, so that each fiber can be heated sufficiently, and the evaporation process of water is accelerated. In order to further increase the evaporation efficiency, the front half of the oven 6 is also deliberately equipped with an exhaust fan. The fans not only can timely discharge the water vapor generated in the oven and keep the air circulation in the oven, but also can avoid the water vapor accumulating in the oven and cause adverse effects on the continuous fiber tows. When the moisture on the surface of the continuous fiber strands is completely evaporated, they smoothly enter the latter half of the oven 6. Here, the infrared heating lamp and the backup roll play a key role again. By adjusting the power and the irradiation angle of the infrared heating lamp, the uniform preheating of the thermoplastic resin on the surface of the fiber tows can be realized. Meanwhile, the rolling action of the supporting roller further promotes the uniform distribution and preheating effect of the resin. Through the series of fine operations, the processing process of the continuous fiber tows in the oven can be effectively and stably carried out, and the quality and performance of the product are greatly improved. The finally obtained continuous fiber tows reach extremely high standards in terms of appearance and internal quality, and provide firm guarantee for subsequent processing and use.
The thermoplastic resin after the preheating is tightly adhered to the continuous fiber tows, and the thermoplastic resin is slowly discharged from the oven 6 together with the continuous fiber tows, and steadily enters the inside of the high-temperature constant-pressure die plate 7. This is a critical step in the overall process and requires precise control of temperature and pressure to ensure that the thermoplastic resin is perfectly incorporated into the continuous fiber strands. Advanced inverter technology is employed in order to ensure that the electromagnetic energy reaches the set temperature quickly and accurately. Through the frequency of accurate adjustment converter, can realize the accurate control to electromagnetic heating speed. When electromagnetically heated to a predetermined temperature, the thermoplastic resin starts to become gradually soft and gradually enters a molten state under the traction of the continuous fiber tow. In this process, the high temperature constant pressure die plate 7 plays a critical role. It can not only provide a stable heating environment, but also ensure that the thermoplastic resin can uniformly penetrate every minute place of the continuous fiber strands by precise pressure control. Thus, the thermoplastic resin is already perfectly integrated with the continuous fiber strands as they pass through the die plate.
The thermoplastic resin in a molten state is rapidly and stably introduced into the leveling and calendaring mechanism 8 by the strong traction force. This mechanism is a large bright spot on the whole production line and is equipped with 3 carefully designed calender rolls with different high, medium and low temperatures. The 3 calender rolls work together to ensure that the resin is able to complete the impregnation and cooling crystallization process under optimal conditions. First, the high temperature calender roll further promotes the melting and flow of the resin by utilizing its high temperature characteristics, so that it penetrates more deeply between each fiber of the continuous fiber tow. Then, the intermediate temperature casting roll plays a transitional role, which not only ensures the continuous impregnation of the resin, but also starts to prepare for the subsequent cooling crystallization. Finally, the low temperature calender roll is responsible for rapidly cooling the resin to crystallization temperature, allowing it to rapidly solidify and bond tightly with the continuous fiber tow. In the whole process, the flatness and the precision of the calendaring roller play a vital role. They ensure not only that the resin is uniformly distributed on the continuous fiber strands, but also that a firm bond is formed between the resin and the continuous fibers by the precise calendering forces. Thus, when the continuous fiber strands come out of the leveling calender 8, a fiber reinforced resin prepreg having excellent properties has been obtained, whose fibers and resin have reached a perfectly set state.
After the precise treatment by the flattening and calendaring mechanism 8, the shaped prepreg already presents a stable and high quality continuous fiber and resin shaped state. Subsequently, the prepregs enter the trimming and winding mechanism 9, and are ready for trimming and winding operations. In the trimming step, the prepreg is subjected to the accurate matching action of the pneumatic dividing knife and the bed knife. The pneumatic dividing knife ensures the accuracy and smoothness of cutting by flexible pneumatic control and sharp blade. The bed knife firmly supports the prepreg so that it remains stable during the cutting process. The prepreg is accurately cut according to the preset size by the cooperative work of the prepreg and the product, so that the integrity of the product is maintained, and the redundant edge part is effectively removed. In terms of waste disposal, the waste material generated during trimming is not discarded at will. Instead, the waste is effectively recovered by the waste winder. The waste winding machine winds the waste in order, so that the subsequent unified treatment or reutilization is facilitated, and the maximum utilization of resources is realized. For finished prepregs, they complete the final winding operation under the action of the finished winder. The finished product winding machine adopts an advanced tension control technology and an accurate winding mechanism, so that the condition that the prepreg is loose or wound too tightly in the winding process is avoided. Meanwhile, the winding machine is further provided with a counting and detecting device, so that the winding length can be recorded in real time, the product quality can be detected, and convenience and guarantee are provided for subsequent packaging and delivery. Through the fine operation of the trimming and winding mechanism 9, the prepreg not only completes trimming and winding operation, but also realizes recycling of waste materials.
The foregoing embodiments are merely illustrative of one or more specific implementations of the invention, which are described in detail and as being specific. However, this is not meant to be a strict limitation on the scope of the invention. It is emphasized that those skilled in the art are fully capable of numerous variations and further optimization modifications without departing from the central concept of the invention. All such variations and modifications are to be regarded as being within the scope of the invention. The scope of the invention should, therefore, be determined with reference to the appended claims.