Wide thermoplastic prepreg mold, production line and preparation method

Abstract

The invention discloses a wide-width thermoplastic prepreg mold, a production line and a preparation method, the wide-width thermoplastic prepreg mold comprises a box body, the box body is provided with a first channel used for feeding a wide-width material; the first channel comprises a melt distribution groove located in the feeding side and an extrusion groove located in the discharging side. The melt distribution pipes are used for feeding melt from the two ends of the melt distribution pipes, and the two melt distribution pipes are symmetrically arranged in the melt distribution groove; a second channel is arranged in the melt distribution pipe; a plurality of melt outlets are formed in the top surface of the melt distribution pipe, and the sizes of the plurality of melt outlets are gradually increased inwards from the two sides of the second channel; and the second channel is communicated with the melt distribution groove through a plurality of melt outlets. Compared with the prior art, the prepreg prepared by the mold disclosed by the invention has the advantages that the thickness can reach 0.3 mm or below, the width can reach 2m, and the prepreg has relatively high mechanical strength and good mechanical property uniformity.

Description

Technical Field

[0001] The invention relates to a wide-width (greater than 0.6 m) thermoplastic prepreg mould, belonging to the field of wide-width thermoplastic prepreg preparation. Background Art

[0002] Thermoplastic prepregs have attracted the attention of domestic and foreign scholars and the engineering community due to their advantages such as light weight, low price, storage resistance, and good corrosion resistance. Thermoplastic resins are solid at room temperature. The methods for preparing continuous fiber reinforced thermoplastic resin materials include: melt impregnation, solvent impregnation, reaction chain growth impregnation, fiber mixing, film lamination, powder impregnation, etc. Among them, the melt impregnation method has been widely used due to its simple equipment requirements, short preparation cycle, less pollution, and continuous production. However, the melt impregnation method has high requirements for the mold. In particular, for large-width prepregs, if fiber tows are used as reinforcement materials to form the prepregs at one time, first, a very large space is required to place the yarn frame; second, the number of tows is too large, and it is very easy to break the wire during the preparation process. When considering using cloth as a reinforcement, the uniformity of the melt along the width direction of the prepreg and the impregnation ability of the fiber must be considered, which puts high requirements on the preparation of the mold. When using traditional molds to prepare wide-width prepregs, it is difficult to achieve uniform heat transfer along the width of the mold due to the increased mold size and uneven heat dissipation. The prepregs prepared in this way have the phenomenon of insufficient material leakage in some areas and burnt material in other areas. Therefore, fiber-reinforced thermoplastic prepregs with a width of more than 0.6m are rarely seen in the market, which also limits the application of fiber-reinforced thermoplastic prepreg cloth. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a wide-width thermoplastic prepreg mold, a production line and a preparation method.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] The present invention first provides a wide-width thermoplastic prepreg mold, comprising a box body, on which are arranged:

[0006] A first channel is used for feeding wide-width materials; the first channel includes a melt distribution groove located on the feeding side and an extrusion groove located on the discharging side;

[0007] The melt distribution pipe is used to feed melt at both ends of the melt distribution pipe. Two melt distribution pipes are symmetrically arranged in the melt distribution trough; a second channel is arranged in the melt distribution pipe; a plurality of melt outlets are arranged on the top surface of the melt distribution pipe, and the sizes of the plurality of melt outlets gradually increase from both sides of the second channel inward; the second channel is connected with the melt distribution trough through the plurality of melt outlets.

[0008] The sizes of the plurality of melt outlets are composed of length and width, and the length and width of the plurality of melt outlets gradually increase from both sides of the second channel inward.

[0009] The length of the minimum melt outlet is in the range of 10-14 cm, the width of the minimum melt outlet is 2-8 cm, and the size of the melt outlet increases with the increase of melt viscosity; the length difference between two adjacent melt outlets is 10-25%, and the width difference between two adjacent melt outlets is 10-25%.

[0010] The melt distribution pipe is a semicircular pipe, and a plurality of melt outlets are arranged on the top surface of the semicircular pipe.

[0011] The distance between the highest points of the two melt distribution pipes is in the range of 1.2-2 times of the designed thickness of the prepreg.

[0012] The box body comprises a front mold and a rear mold, and the front mold and the rear mold are symmetrical; a melt distribution pipe is respectively arranged on the front mold and the rear mold; the melt distribution groove and the extrusion groove are both composed of half grooves opened on the front mold and the rear mold.

[0013] The width of the box is 0.6-2 meters, and the height of the box is 0.3-0.5 times the width.

[0014] The present invention also provides a wide-width thermoplastic prepreg production line, comprising:

[0015] An unwinding device for releasing the fiber cloth;

[0016] A traction device for traction of the fiber cloth;

[0017] The wide-width thermoplastic prepreg mold provided above is arranged between the unwinding device and the traction device to impregnate the released fiber cloth;

[0018] Calendering device, calendering the surface of the fiber cloth after impregnation;

[0019] The winding device is used to wind up the fiber cloth after surface calendering.

[0020] The first channel of the wide-width thermoplastic prepreg mold is placed vertically, and the fiber cloth enters from the top.

[0021] The present invention also provides a method for preparing a wide-width thermoplastic prepreg, comprising:

[0022] After the melt is heated and melted, it enters the wide-width thermoplastic prepreg mold provided above from the four melt inlets of the two melt distribution pipes respectively. Under the action of the injection force, the melt flows along the melt distribution pipes toward the center of the wide-width thermoplastic prepreg mold and flows out from the melt outlet; the melt flowing out from the melt outlet fills the entire melt distribution tank to form an immersion pool;

[0023] The fiber cloth is introduced from the first channel above the wide-width thermoplastic prepreg mold, enters the wide-width thermoplastic prepreg mold, undergoes primary extrusion and primary impregnation through the melt distribution pipe, then undergoes secondary impregnation through the impregnation tank and secondary extrusion through the extrusion tank, and is finally pulled out and solidified into shape.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the impregnation mold of the present invention, the melt is synchronously injected into the melt distribution pipe from the left and right melt inlets of the mold, and flows into the mold impregnation cavity from the melt outlet of the melt distribution pipe. By injecting the melt into the melt distribution pipe and flowing out from the melt outlet until the melt fills the mold impregnation box, the melt can be forced to flow to the middle of the mold, avoiding the phenomenon that the melt flows downward due to its own weight and the traction of the fiber, resulting in a lack of material in the middle of the mold and the melt overflowing from the inlet; the size of the melt outlet on the melt distribution pipe changes, so that the melt pressure on both sides of the mold is greater than the pressure of the middle melt, and the size of the middle melt outlet is larger, which can achieve the same melt outflow, that is, the melt flow rate is consistent along the width direction of the mold, and the melt can be evenly distributed along the width direction of the mold; due to the two extrusion processes through the melt distribution pipe and the extrusion groove, the prepreg can be better entered into the fiber cloth through the secondary extrusion, and the surface of the fiber cloth can be made smoother, and the thickness of the prepreg can be better controlled. The prepreg prepared by this mold can reach a thickness of less than 0.3 mm and a width of 2 meters, and has high mechanical strength and good uniformity of mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a cross-sectional view of a wide-width thermoplastic prepreg mold of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the half mold;

[0028] Figure 3 It is a schematic diagram of the structure of the preparation system of the present invention;

[0029] Figure 4 This is the result diagram of comparative example 1;

[0030] Figure 5 This is the result diagram of Comparative Example 3. DETAILED DESCRIPTION

[0031] Example 1

[0032] This embodiment provides a wide-width thermoplastic prepreg mold, such as Figure 1As shown, the wide-width thermoplastic prepreg mold is a box structure, which is used for the preparation of fiber cloth reinforced thermoplastic resin prepreg. The mold width is 0.6-2 meters, and the height is 0.3-0.5 times the width. It includes a front mold and a rear mold, wherein the front mold and the rear mold are mirror-symmetrical. The mold is suitable for preparing prepregs with a width of 0.6-2m, because when the width is less than 0.6m, fiber tows can be directly used as reinforcing materials; when the width is greater than 2m, the temperature uniformity control requirements for the width direction of the mold are higher, and the current market lacks corresponding application requirements. The mold height determines the amount of melt stored inside the mold and the amount of contact between the fiber cloth and the melt. If the mold height is too small, the contact time between the fiber cloth and the melt is limited, which easily causes insufficient impregnation of the melt into the fiber cloth; if the height is too large, the weight of the resin melt in the mold is too large, the resistance to pulling the fiber cloth increases, and the resin is heated for too long, which easily causes the phenomenon of resin burning.

[0033] The impregnation mold is a box structure, and the box 1 is provided with:

[0034] The first channel 2 is used for feeding wide-width materials; the first channel 2 includes a melt distribution groove 21 located on the feeding side and an extrusion groove 22 located on the discharging side;

[0035] The melt distribution pipe 3 is used to feed melt at both ends of the melt distribution pipe. Two melt distribution pipes are symmetrically arranged in the melt distribution groove; a second channel 4 is arranged in the melt distribution pipe; a plurality of melt outlets 5 are arranged on the top surface of the melt distribution pipe, and the sizes of the plurality of melt outlets 5 gradually increase from both sides of the second channel inward; the second channel is connected to the melt distribution groove 21 through the plurality of melt outlets.

[0036] The impregnation mold is composed of two half molds, and the structure of the half mold is as follows Figure 2 As shown, the melt distribution pipe 3 is two independent semicircular tubular structures, and the second channel 4 inside the melt distribution pipe is the main channel.

[0037] The cross section of the second channel 4 is a semicircle, and the radius of the semicircle is 10-20cm. If the height of the highest point from the mold wall is too small, the mold is small, the amount of melt flowing into the main channel is limited, the mold wall has a large resistance to the melt, and leakage is easy to occur; if the height of the highest point from the mold wall is too large, the melt flow rate is large, the melt is more difficult to be heated evenly, and the quality of the prepared product is easy to be unqualified. The melt outlets 5 at the same position from the inlet on both sides of the main channel have the same size. The number of melt outlets can be even or odd. When it is an even number, the two melt outlets close to the central axis of the mold along the width direction are recorded as N and N' respectively; when it is an odd number, the middle one is recorded as melt outlet N, and melt outlet N is symmetrical about.

[0038] The melt outlets with different numbers have different lengths and widths. The length of the melt outlet ranges from 10 to 20 cm, and the width of the melt outlet ranges from 2 to 15 cm. The size of the melt outlet gradually increases from both sides to the middle, and the difference in the single-side size of two adjacent melt outlets is 10 to 25%. And the size of the melt outlet increases with the increase of the melt viscosity.

[0039] The central axes of all melt outlets 5 are on one line, and the central axes are located at the highest point of the main channel arc from the mold wall.

[0040] The distance between the highest points of the main channels of the two half molds is 1.2-2 times the design thickness of the prepreg. This distance is used for the first extrusion of the fiber cloth. If the distance is too small, it is easy to leak and the subsequent traction requirements are high; if the distance is too large, the extrusion effect cannot be achieved.

[0041] The extrusion groove 22 below the melt distribution groove 21 can extrude the fiber cloth impregnated with resin. The thickness of the extrusion groove 22 is 1 times the design thickness of the prepreg.

[0042] Comparative Example 1

[0043] The highest point of the main channel is 20cm high from the mold wall, and there are 10 melt outlets of the same size, each with a length of 15cm and a width of 5cm. The central axes of all melt outlets are on a line, and the central axis is located at the highest point of the main channel arc from the mold wall. The distance between the highest points of the main channel of the front mold and the main channel of the rear mold is 1.2 times the design thickness of the prepreg. An extrusion groove is provided under the mold to extrude the fiber cloth impregnated with resin. The thickness of the extrusion groove is 1 times the design thickness of the prepreg. The thickness of the prepreg prepared in this way is 0.3mm. However, the thickness of the prepreg is thicker on both sides, and leakage occurs in the middle, see Figure 4 The position of the middle rectangle.

[0044] Comparative Example 2

[0045] The mold is 2 meters wide and 1 meter high. The wide prepreg mold is placed vertically, with the fiber cloth inlet facing up and the fiber cloth prepreg outlet facing down. The main channel is arc-shaped, with the highest point 20 cm above the mold wall. There are 9 melt outlets, with sizes of 10*2, 12*3, 14*4, 16*5, 18*6, 16*5, 14*4, 12*3, and 10*2 (in cm*cm). The central axes of all melt outlets are on the same line, and the central axis is located at the highest point of the main channel arc from the mold wall. The distance range between the highest points of the two half-mold main channels is 2.5 times the design thickness of the prepreg. An extrusion groove is provided under the mold, with a thickness of 1 times the design thickness of the prepreg. Because the distance range between the highest points of the two half-mold main channels is too large, the set prepreg thickness is 0.3 mm, and the actual prepreg thickness is 0.6 mm, which is much larger than the design thickness.

[0046] Comparative Example 3

[0047] The mold is 2 meters wide and 1.5 meters high. The wide prepreg mold is placed vertically, with the fiber cloth inlet facing upward and the fiber cloth prepreg outlet facing downward. The main channel is arc-shaped, with the highest point 20 cm above the mold wall. There are 9 melt outlets with sizes of 10*2, 12*3, 14*4, 16*5, 18*6, 16*5, 14*4, 12*3, and 10*2 (unit: cm*cm). The central axes of all melt outlets are on a line, and the central axis is located at the highest point of the main channel arc from the mold wall. The distance between the highest points of the two half-mold main channels is 1.2 times the design thickness of the prepreg. An extrusion groove is provided under the mold, with a thickness of 1 times the design thickness of the prepreg. Due to the excessive height of the mold and the large traction resistance, the molding rate is greatly reduced, and the resin is burned inside, see Figure 5 The position of the rectangle.

[0048] Example 2

[0049] This embodiment provides a wide-width thermoplastic prepreg production line, such as Figure 3 As shown. Includes:

[0050] An unwinding device 10, for releasing the fiber cloth;

[0051] A traction device 20 for traction of the fiber cloth;

[0052] The wide-width thermoplastic prepreg mold 30 provided above is arranged between the unwinding device and the traction device to impregnate the released fiber cloth;

[0053] A calendering device 40 is used to calender the surface of the fiber cloth after impregnation;

[0054] The winding device 50 is used to wind up the fiber cloth after the surface is calendered.

[0055] The first channel of the wide thermoplastic prepreg mold 30 is placed vertically, with the fiber cloth inlet direction facing upward and the fiber cloth prepreg outlet direction facing downward.

[0056] The calendering device 40 is a pair of calendering rollers.

[0057] A guide roller 60 is also provided at the outlet of the wide thermoplastic prepreg mold 30 .

[0058] Example 3

[0059] This embodiment provides a method for preparing wide-width thermoplastic prepreg: after the melt is heated and melted, it enters the mold from a total of four melt inlets of the main channels of the front mold and the rear mold respectively. Under the action of the injection force, the melt flows toward the center of the mold respectively; at the same time, the melt flows out from the melt outlet. The melt flowing out of the melt outlet fills the entire impregnation mold to form an impregnation pool. The fiber cloth is introduced from the top of the mold, enters the mold, passes through the main channel, and completes preliminary flattening and impregnation under the action of the first extrusion; it is pulled downward by the traction force, impregnated and extruded by the resin melt, and impregnation is completed; it is extruded for the second time in the extrusion groove below the impregnation mold, and finally pulled out to solidify and form.

[0060] The injection pressure, injection speed and injection force of the four melt inlets should remain exactly the same.

Claims

1. A wide thermoplastic prepreg mold, characterized in that: It comprises a box body, on which are arranged: A first channel is used for feeding wide-width materials; the first channel includes a melt distribution groove located on the feeding side and an extrusion groove located on the discharging side; The melt distribution pipe is used to feed melt at both ends of the melt distribution pipe. Two melt distribution pipes are symmetrically arranged in the melt distribution trough; a second channel is arranged in the melt distribution pipe; a plurality of melt outlets are arranged on the top surface of the melt distribution pipe, and the sizes of the plurality of melt outlets gradually increase from both sides of the second channel inward; the second channel is connected with the melt distribution trough through the plurality of melt outlets.

2. The wide-width thermoplastic prepreg mold according to claim 1, characterized in that: The sizes of the plurality of melt outlets are composed of length and width, and the length and width of the plurality of melt outlets gradually increase from both sides of the second channel inward.

3. The wide-width thermoplastic prepreg mold according to claim 2, characterized in that: The length of the minimum melt outlet is in the range of 10-14 cm, the width of the minimum melt outlet is in the range of 2-8 cm, and the size of the melt outlet increases with the increase of melt viscosity; the length difference between two adjacent melt outlets is 10-25%, and the width difference between two adjacent melt outlets is 10-25%.

4. The wide-width thermoplastic prepreg mold according to claim 3, characterized in that: The melt distribution pipe is a semicircular pipe, and a plurality of melt outlets are arranged on the top surface of the semicircular pipe.

5. The wide-width thermoplastic prepreg mold according to claim 4, characterized in that: The distance between the highest points of the two melt distribution pipes is in the range of 1.2-2 times of the designed thickness of the prepreg.

6. The wide-width thermoplastic prepreg mold according to claim 1, characterized in that: The box body comprises a front mold and a rear mold, and the front mold and the rear mold are symmetrical; a melt distribution pipe is respectively arranged on the front mold and the rear mold; the melt distribution groove and the extrusion groove are both composed of half grooves opened on the front mold and the rear mold.

7. The wide-width thermoplastic prepreg mold according to any one of claims 1 to 6, characterized in that: The width of the box is 0.6-2 meters, and the height of the box is 0.3-0.5 times the width.

8. A wide-width thermoplastic prepreg production line, characterized in that: include: An unwinding device for releasing the fiber cloth; A traction device for traction of the fiber cloth; The wide-width thermoplastic prepreg mold according to any one of claims 1 to 7 is arranged between the unwinding device and the traction device to impregnate the released fiber cloth; Calendering device, calendering the surface of the fiber cloth after impregnation; The winding device is used to wind up the fiber cloth after surface calendering.

9. A wide-width thermoplastic prepreg production line according to claim 8, characterized in that: The first channel of the wide-width thermoplastic prepreg mold is placed vertically, and the fiber cloth enters from the top.

10. A method for preparing a wide-width thermoplastic prepreg, characterized in that: include: After the melt is heated and melted, it enters the wide-width thermoplastic prepreg mold according to any one of claims 1 to 7 from two melt distribution pipes with a total of four melt inlets. Under the action of injection force, the melt flows along the melt distribution pipes toward the center of the wide-width thermoplastic prepreg mold and flows out from the melt outlet; the melt flowing out from the melt outlet fills the entire melt distribution tank to form an immersion pool; The fiber cloth is introduced from the first channel above the wide-width thermoplastic prepreg mold, enters the wide-width thermoplastic prepreg mold, undergoes primary extrusion and primary impregnation through the melt distribution pipe, then undergoes secondary impregnation through the impregnation tank and secondary extrusion through the extrusion tank, and is finally pulled out and solidified into shape.

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