Combined melt impregnation die head and melt impregnation die system

Abstract

The utility model discloses a combined type melt dipping die head and melt dipping die system, belongs to orthopaedic implant processing technical field, the combined type melt dipping die head comprises an upper die plate and a lower die plate, a die cavity is formed between the upper die plate and the lower die plate, at least two detachable dipping blocks are arranged below the upper die plate, and the dipping blocks are arranged below the lower die plate. Each dipping block is provided with a height adjusting device for adjusting the height of the dipping block; a first tooth surface is arranged on the lower surface of the dipping block, a second tooth surface is arranged on the upper surface of the lower mold plate, so that a wavy resin runner is formed between the dipping block and the lower mold plate in the mold cavity, and the included angle between two adjacent fold lines of the wavy structure of the resin runner is (0 degree, 180 degrees). The device is particularly suitable for bioactive glass fibers, the impregnation effect is good, the coating angle of a fiber bundle can be accurately adjusted on line, and the preparation performance of a composite material is effectively improved.

Description

Technical Field

[0001] The utility model relates to the technical field of orthopedic implant processing, in particular to a combined melt-impregnation die head and a melt-impregnation mold system. Background Art

[0002] The clinical problems existing in traditional metal bone fixation devices have not been effectively solved. Although they meet the structural strength required by bone tissue, they are not absorbable in the body and require secondary surgery to remove, which poses potential surgical risks and heavy economic burdens to patients; they have a large elastic modulus, a stress shielding effect, and are prone to bone resorption; the metal debris / ions produced by long-term corrosion are harmful to the human body; they have imaging interference; and they affect children's bone development. Therefore, the development of absorbable bone fixation devices is one of the important ways to solve current clinical problems. At present, the absorbable bone fixation devices on the market are mainly PLA (polylactic acid) and its modified materials. However, the existing absorbable PLA or PLGA (polylactic acid-glycolic acid copolymer) bone fixation devices have outstanding problems such as insufficient mechanical strength, mismatch between degradation rate and tissue healing rate, and poor bone induction ability, which limit their application areas.

[0003] At present, domestic and foreign manufacturers are using composite material technology to solve the above problems. Ossio, an American company, uses the absorbable bioactive glass fiber reinforced polylactic acid composite material system developed by the project team to prepare internal fixation screws for small bones of the limbs. Its strength is 1.5 times that of cortical bone, and its mechanical properties are significantly higher than those of inorganic particle reinforced products. The degradation cycle is 2 years. So far, there are no absorbable bioactive glass fiber reinforced PLA or PLGA composite bone fixation devices in China.

[0004] In order to solve the outstanding problems of insufficient mechanical properties and mismatch between degradation rate and tissue healing rate in absorbable bone internal fixation devices, it is necessary to optimize the molding equipment and production process of bioactive glass fiber reinforced PLA or PLGA composite materials, design and develop the continuous fiber reinforced thermoplastic resin melt impregnation mold system and preparation process, and focus on solving the following outstanding problems in the field of absorbable orthopedic internal fixation devices: 1. The strength of bioactive glass fiber is lower than that of industrial glass fiber (under the same test standard, the tensile strength of bioactive glass fiber dipped yarn is about 200Mpa-400Mpa, and the tensile strength of industrial glass fiber dipped yarn is about 2000Mpa-2400Mpa), and it is easy to break during pultrusion; 2. The insufficient mechanical properties need to be solved from the perspective of glass fiber content and the interface properties between glass fiber and resin; 3. The degradation rate can be controlled by regulating the physical and chemical properties such as the characteristic viscosity value, molecular weight and its distribution, and glass fiber content of the composite material.

[0005] Continuous fiber reinforced thermoplastic resin-based composites are high-performance composites made of thermoplastic resin as matrix material and continuous fiber as reinforcement material through various composite molding processes. Continuous fiber reinforced thermoplastic composites make up for the limitations of fiber length and fiber continuity on the performance of composites. With its excellent mechanical properties and mechanical properties, it is widely used in aerospace, transportation, medical equipment, power engineering, industrial manufacturing, building materials and other industries.

[0006] The existing continuous fiber reinforced thermoplastic resin melt impregnation die design has at least the following problems: 1. It belongs to the conventional industrial field, not the orthopedic implant field, and does not use low-strength bioactive glass fibers; 2. The impregnation die is single, generally consisting of only one impregnation unit, the impregnation effect is poor, and it is difficult to control the surface quality of the impregnated material strips; 3. It is difficult to accurately adjust the covering angle of the fiber bundle in the impregnation mold online. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide a combined melt impregnation die head and a melt impregnation mold system suitable for bioactive glass fibers, with good impregnation effect and capable of accurately adjusting the fiber bundle covering angle online.

[0008] In order to solve the above technical problems, the utility model provides the following technical solutions:

[0009] On the one hand, a combined melt impregnation die is provided for manufacturing a continuous fiber reinforced thermoplastic resin composite material, wherein the continuous fiber is a bioactive glass fiber, the combined melt impregnation die comprises an upper template and a lower template arranged opposite to each other, a mold cavity is formed between the upper template and the lower template, wherein:

[0010] At least two detachable impregnation blocks are provided below the upper template, and each impregnation block is provided with a height adjustment device for adjusting the height of the impregnation block;

[0011] The lower surface of the impregnation block is provided with a first tooth surface, and the upper surface of the lower template is provided with a second tooth surface, so that a wavy resin flow channel is formed between the impregnation block and the lower template in the mold cavity, and the angle between two adjacent fold lines of the wavy structure of the resin flow channel is (0°, 180°);

[0012] The mold cavity is provided with a yarn inlet at one end of the resin flow channel, and the mold cavity is provided with a material outlet at the other end of the resin flow channel.

[0013] Furthermore, the height adjustment device includes a height adjustment screw, which is threadedly connected to the upper template, and its end passes through the upper template and is connected to the impregnation block, and a compass with a scale is fixed on the height adjustment screw.

[0014] Furthermore, the upper template is threadedly connected with fastening screws above both ends of each impregnation block, and the ends of the fastening screws pass through the upper template and abut against the impregnation block;

[0015] And / or, the second tooth surface on the lower template and the first tooth surface on the corresponding impregnation block have the same angle and height;

[0016] And / or, the angle between two adjacent fold lines of the wavy structure of the resin flow channel is (45°, 180°).

[0017] Furthermore, the sides of the upper template and the lower template are provided with detachable discharge plates, the discharge hole is located on the discharge plate, and the discharge hole includes a first conical section and a first straight section in sequence.

[0018] Furthermore, the maximum opening of the first tapered section is smoothly connected to the mold cavity;

[0019] And / or, the angle of the first tapered section is 20°-60°;

[0020] And / or, the length of the first tapered section is 5 mm-20 mm;

[0021] and / or, a smooth transition between the first tapered section and the first straight section;

[0022] And / or, the length of the first straight section is 1 mm-20 mm;

[0023] And / or, the first straight section is designed as a circular hole with a hole diameter ranging from 0.1 mm to 5 mm;

[0024] And / or, the outlet of the first straight section is chamfered;

[0025] and / or, the number of teeth on the first tooth surface and the second tooth surface are both 3-20;

[0026] And / or, the tooth tops of the first tooth surface and the second tooth surface are both chamfered;

[0027] And / or, the number of the discharge holes is 1-50, which is the same as the number of fiber bundles to be impregnated.

[0028] Furthermore, the single covering angle produced by a single tooth on one side of the first tooth surface and the second tooth surface on the fiber bundle to be impregnated is (0°, 30°), and the total covering angle produced by the melt impregnation die head on the fiber bundle to be impregnated is (0°, 105.3°).

[0029] Furthermore, a single covering angle produced by a single tooth on one side of the first tooth surface and the second tooth surface on the fiber bundle to be impregnated is 1°-15°, and a total covering angle produced by the combined melt impregnation die head on the fiber bundle to be impregnated is 56.2°-101.6°.

[0030] On the other hand, a melt impregnation die system is provided, comprising a fiber pre-dispersing device, a combined melt impregnation die head and a traction device connected in sequence, wherein the combined melt impregnation die head is the combined melt impregnation die head described above.

[0031] Furthermore, the fiber pre-dispersing device includes at least three fixed shafts arranged at equal intervals laterally, each fixed shaft is provided with a dispersion roller, the axis of the dispersion roller is spaced a preset distance from the corresponding fixed shaft, the dispersion roller is connected to the corresponding fixed shaft with the corresponding fixed shaft as the center and with an adjustable angle, and the fixed shaft is provided with a dispersion roller angle adjustment device.

[0032] Furthermore, the diameter of the dispersion roller is 30 mm to 120 mm;

[0033] And / or, the dispersion roller angle adjustment device is provided with a compass for recording the dispersion roller angle;

[0034] And / or, a heating rod and a thermocouple are provided inside the dispersion roller, and the temperature of the dispersion roller after heating is 80° C.-240° C.;

[0035] And / or, the dispersion roller is provided with a pressure sensor for detecting the tension of the fiber bundle;

[0036] And / or, a cooling device and a post-coating device are sequentially connected between the combined melt impregnation die head and the traction device;

[0037] And / or, the traction speed of the traction device ranges from 1 m / min to 100 m / min.

[0038] The utility model has the following beneficial effects:

[0039] The utility model discloses a combined melt impregnation die head and a melt impregnation die system, wherein the die head comprises an upper die plate and a lower die plate which are arranged relatively to each other, at least two detachable impregnation blocks are arranged below the upper die plate, each impregnation block is provided with a height adjustment device for adjusting the height of the impregnation block, and the adjustable range of the impregnation block height is from zero to the wave peak height value of the wavy flow channel, that is, the adjustable range of a single coating angle of the fiber bundle in the impregnation die is from 0° to the corresponding coating angle when the impregnation block is completely close to the lower die plate; compared with the impregnation roller in the prior art which can adjust the coating angle online, the single coating angle generated by the impregnation block in the utility model is significantly lower than the single coating angle generated by the impregnation roller, and the fiber bundle has no large fold angle when moving in the die, which can effectively reduce the probability of single filament breakage in the fiber bundle and thus meet the impregnation requirements of fiber bundles with a larger range of TEX values; the wavy impregnation block can also effectively reduce the volume of the die cavity, avoid the excessive resin from being accumulated in the die cavity for a long time due to the large volume of the die cavity, and cause the resin to be carbonized, thereby improving the yield rate of the impregnated silk product. The utility model is particularly suitable for bioactive glass fibers, has a good impregnation effect, can accurately adjust the fiber bundle wrapping angle online, and effectively improves the preparation performance of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a schematic diagram of the cross-sectional structure of the combined melt impregnation die head of the utility model;

[0041] Figure 2 for Figure 1 A partial cross-sectional view of

[0042] Figure 3 for Figure 1 Left view of

[0043] Figure 4 for Figure 1 Schematic diagram of the enlarged structure of a single impregnated block;

[0044] Figure 5 It is a schematic diagram of the overall structure of the melt impregnation mold system of the utility model;

[0045] Figure 6 It is the microscopic morphology of the wire corresponding to different covering angles in the utility model;

[0046] Figure 7 The figures are comparison diagrams of wire micro-morphology, wherein (a) is the micro-morphology of wire prepared by conventional melt impregnation die head in the prior art, and (b) is the micro-morphology of wire prepared by the melt impregnation die system of the present invention. DETAILED DESCRIPTION

[0047] In order to make the technical problems to be solved, technical solutions and advantages of the present invention more clear, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0048] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0049] The more common preparation processes for continuous fiber reinforced thermoplastic resin composites currently include melt impregnation process, solution pre-impregnation process, powder impregnation process and mixed yarn impregnation process. Among them, the more commonly used is the melt impregnation process, which utilizes the characteristics of thermoplastic resin melting when heated, uses an extruder to extrude the molten thermoplastic resin into a heated and heat-insulated mold, and the continuous fiber uses a traction device to provide tension through the mold cavity filled with thermoplastic resin melt. Under the combined action of tension and pressure, the fiber yarn spreading (highly bundled fibers are dispersed and spread into a loose state by various means, which can also be called fiber opening or bundle opening) impregnation is achieved. The core of the melt impregnation process is the fiber yarn spreading and impregnation. The designs of different structures and shapes of existing impregnation molds are all for improving the dispersion degree of fibers and the impregnation effect of fibers. Common designs include curved impregnation flow channel molds, resin split jet impregnation molds, and adjustable wrapping angle slit roller impregnation molds. The mold structure and shape design is one of the most core influencing factors of the thermoplastic resin melt impregnation process, but there are some problems with the existing public impregnation mold designs.

[0050] The Chinese utility model patent with publication number CN2892438Y discloses a device for rolling production of long fiber reinforced plastic particles. The device uses multiple sets of rollers to press the resin slurry on the surface of the long fiber into the fiber bundle, thereby achieving the internal impregnation effect of the fiber bundle. However, this device does not have a resin melting mold and a fiber yarn spreading device. The large temperature difference between the fiber and the resin affects the resin impregnation effect. At the same time, the pressure of the rollers cannot be accurately controlled, which easily causes fiber breakage and affects production efficiency.

[0051] In the Chinese utility model patent with publication number CN204674042U, a melt impregnation die head system is mentioned. This device improves the problem of uneven pressure and flow when the molten resin enters the impregnation tank to a certain extent through a melt guide device with a flow channel inner core and multiple discharge ports with gradually increasing diameters and multiple tension roller glass fiber impregnation devices placed at the lower position of the impregnation tank. The detachable guide roller and tension shaft frame system improves production efficiency. In this device design, the molten resin flows in many branch channels for a long time and is heated. The small diameter of the branch channel has a large shear force on the resin, which can easily cause serious loss of resin molecular weight and even problems such as accumulation and carbonization. In addition, the pressure and flow in the flow channel are difficult to actively and accurately control and there are no monitoring measures. The mold cavity pressure may be high due to the large amount of resin in the mold cavity, resulting in frequent production problems such as broken strips that reduce production efficiency.

[0052] In the Chinese invention patent with publication number CN106903906B, a melt impregnation device and preparation method for adjusting the coating angle of a fiber bundle in an impregnation mold online are disclosed. The device is provided with at least one slit roller capable of rotating in both positive and negative directions along the circumferential direction in the impregnation mold, and a slit with a width smaller than its radius is opened in the radial direction of the slit roller to allow the fiber bundle to pass through. The function of adjusting the coating angle of the fiber bundle in the impregnation mold is realized by rotating the slit roller, which improves the degree of impregnation of the fiber bundle to a certain extent. However, in this melt impregnation device, changing the single coating angle of the fiber bundle in the die head by rotating the slit roller will cause a large local tension of the fiber bundle, resulting in serious wear of the fiber bundle at the slit and easy yarn breakage, thereby reducing production efficiency. The impregnation tank space required for the staggered arrangement of the dispersion roller and the slit roller is large, which is easy to cause the resin to accumulate and be heated for a long time, thereby causing carbonization and affecting the quality of the product. At the same time, the wool yarn and broken yarn generated when the fiber bundle passes through the impregnation tank are not easy to be taken out of the mold cavity, which is not conducive to long-term production.

[0053] The existing continuous fiber reinforced thermoplastic resin melt impregnation die design has at least the following problems: 1. It belongs to the conventional industrial field, not the field of orthopedic implants, and does not use low-strength bioactive glass fibers; 2. The impregnation die is single, generally consisting of only one impregnation unit, the impregnation effect is poor and it is difficult to control the surface quality of the impregnated material strip; 3. It is difficult to accurately adjust the wrapping angle of the fiber bundle in the impregnation mold online. In order to solve the above problems, the utility model provides the following technical solutions.

[0054] On the one hand, the utility model provides a combined melt impregnation die head 1 for manufacturing a continuous fiber reinforced thermoplastic resin composite material, wherein the continuous fiber is a bioactive glass fiber (absorbable), such as Figure 1-4 As shown, the combined melt impregnation die head 1 comprises an upper template 11 and a lower template 12 arranged opposite to each other, and a mold cavity 13 is formed between the upper template 11 and the lower template 12, wherein:

[0055] At least two detachable impregnation blocks 14 (may be 3-6, 3 in the embodiment shown in the figure) are provided below the upper template 11, and each impregnation block 14 is provided with a height adjustment device for adjusting the height of the impregnation block 14;

[0056] The lower surface of the impregnation block 14 is provided with a first tooth surface 141, and the upper surface of the lower mold plate 12 is provided with a second tooth surface 121, so that a wavy resin flow channel is formed between the impregnation block 14 and the lower mold plate 12 in the mold cavity 13, and the angle θ between two adjacent fold lines of the wavy structure of the resin flow channel is (0°, 180°), and can be specifically 45°-180°;

[0057] The mold cavity 13 is provided with a yarn inlet 131 at one end of the resin flow channel, and a discharge hole (as a molding hole) 171 at the other end of the resin flow channel. In addition, the mold cavity 13 is provided with a feed port (not shown), and the molten resin delivered by the extruder (specifically, a twin-screw extruder) is delivered into the mold cavity 13 through the feed port.

[0058] When in use, the thermoplastic resin is plasticized by the extruder and then extruded into the mold cavity 13 of the combined melt impregnation die 1. At this time, the thermoplastic resin is distributed in the wavy resin flow channel formed by the first tooth surface 141 on the lower surface of the impregnation block 14 and the second tooth surface 121 on the upper surface of the lower template 12. The single fold line on the first tooth surface 141 forms a single wrapping angle with the horizontal line. After covering the upper template 11, the height of the impregnation block 14 can be adjusted by the height adjustment device, thereby adjusting the single wrapping angle of the fiber bundle in the mold cavity 13, thereby improving the yarn spreading and impregnation of the fiber bundle in the mold cavity 13.

[0059] The combined melt impregnation die head of the utility model comprises an upper template and a lower template which are arranged relatively, at least two detachable impregnation blocks are arranged below the upper template, each impregnation block is provided with a height adjustment device for adjusting the height of the impregnation block, and the adjustable range of the impregnation block height is from zero to the wave peak height value of the wavy flow channel, that is, the adjustable range of a single coating angle of the fiber bundle in the impregnation mold is from 0° to the corresponding coating angle when the impregnation block is completely close to the lower template; compared with the impregnation roller in the prior art which can adjust the coating angle online, the single coating angle generated by the impregnation block in the utility model is significantly lower than the single coating angle generated by the impregnation roller, and the fiber bundle has no large fold angle when moving in the mold, which can effectively reduce the probability of single filament breakage in the fiber bundle and thus meet the impregnation requirements of fiber bundles with a larger range of TEX values; the wavy impregnation block can also effectively reduce the mold cavity volume, avoid the excessive resin from being accumulated in the mold cavity for a long time due to the large mold cavity volume, resulting in resin carbonization, and improve the yield rate of the impregnated silk product.

[0060] In addition, the detachable impregnation block is easy to disassemble and assemble, and the operation is simple. Multiple impregnation blocks arranged side by side can effectively increase the number of times and time of impregnation on one side of the fiber bundle in the mold, and improve the impregnation effect of the fiber bundle; each detachable impregnation block can be adjusted independently of each other, and the impregnation coating angle and mold cavity volume can be adjusted in blocks and regions according to different resin and fiber requirements. At the same time, the detachable impregnation block can be replaced with a wavy design of different angles according to needs, which expands the range of resins and fibers applicable to the combined impregnation mold. Therefore, the combined melt impregnation die head of the utility model is particularly suitable for bioactive glass fibers, and is suitable for the subsequent use of composite materials to manufacture orthopedic implants (such as bone nails, bone plates, etc.). It has a good impregnation effect, can accurately adjust the fiber bundle coating angle online, and effectively improve the preparation performance of composite materials.

[0061] The height adjustment device can be in various forms that can be easily thought of by those skilled in the art. The present invention preferably adopts the following structural forms:

[0062] The height adjustment device includes a height adjustment screw 15, which is threadedly connected to the upper template 11, and its end passes through the upper template 11 and is connected to the impregnation block 14 (specifically, it can be connected to the middle part of the impregnation block 14), and a compass 151 with a scale is fixed on the height adjustment screw 15 (specifically, it can be welded).

[0063] When in use, the compass 151 can rotate with the rotation of the height adjustment screw 15. Different rotation angles of the height adjustment screw 15 correspond to different wrapping angles. In particular, the height of each dipping block 14 can be adjusted individually. In this way, the height of each dipping block 14 can be accurately adjusted and is easy to use.

[0064] In order to fix the height of the impregnation block 14, fastening screws 16 can be threadedly connected above the two ends of each impregnation block 14 on the upper template 11. The ends of the fastening screws 16 pass through the upper template 11 and abut against the impregnation block 14. In this way, the impregnation block 14 is designed to be detachable and is fixed to the frame of the upper template 11 by the fastening screws 16 on both sides of the impregnation block 14. When disassembling, it is only necessary to remove the fastening screws 16 to remove the impregnation block 14.

[0065] When adjusting the height of the impregnation block 14, the rotation angle of the compass 151 on the height adjustment screw 15 can be calculated first according to the total coverage angle that needs to be adjusted, and then the two fastening screws 16 at both ends of the single impregnation block 14 can be loosened, and the compass 151 can be rotated to the specified position as needed (that is, the height adjustment screw 15 can be rotated), and finally the two fastening screws 16 at both ends of the impregnation block 14 can be tightened to complete the adjustment of the coverage angle of the single impregnation block 14.

[0066] The second tooth surface 121 on the lower template 12 and the first tooth surface 141 on the corresponding impregnation block 14 can have the same angle and height to facilitate calculation and adjustment of the covering angle. The number of teeth on the first tooth surface 141 and the second tooth surface 121 can be flexibly set as needed, and can be 3-20, such as 5, 8, 10, 15, etc.; the tooth tops of the first tooth surface 141 and the second tooth surface 121 can be chamfered, which can effectively alleviate the yarn breakage caused by mechanical friction of the fiber bundle.

[0067] The single covering angle produced by a single tooth on one side of the first tooth surface 141 and the second tooth surface 121 on the fiber bundle 4 to be impregnated can be (0°, 30°), preferably 1-15 degrees, and the total covering angle produced by the combined melt impregnation die head 1 on the fiber bundle to be impregnated can be (0°, 105.3°), preferably 50-104 degrees. At this time, the impregnation effect and the corresponding silk glass fiber distribution and the interface between the glass fiber and the resin are well combined.

[0068] The sides of the upper template 11 and the lower template 12 may be provided with a removable discharge plate 17, on which a discharge hole 171 is located. The discharge hole 171 includes a first conical section 1711 and a first straight section 1712 in sequence, so that the discharge plate 17 with different apertures can be disassembled and replaced as needed.

[0069] In specific implementation, the first tapered section 1711 is connected to the end near the mold cavity, and its maximum opening can be smoothly connected to the mold cavity 13 to alleviate the breakage of the fiber bundle caused by mechanical friction; the angle of the first tapered section 1711 can be 20°-60°, such as 30°, 40°, 50°, etc., and this angle has a good effect; the length of the first tapered section 1711 can be 5mm-20mm, specifically 5mm-15mm, such as 8mm, 10mm, 12mm, etc.; the first tapered section 1711 and the first straight section 1712 can be smoothly transitioned to alleviate the breakage of the fiber bundle caused by mechanical friction. The length of the first straight section 1712 can be 1mm-20mm, specifically 4mm-10mm, such as 5mm, 7mm, 9mm, etc. The first straight section 1712 can be designed as a round hole with a hole diameter range of 0.1mm-5mm, specifically 0.3mm-3mm, such as 0.8mm, 1mm, 2mm, etc., which can be flexibly selected according to the diameter of the fiber bundle; the outlet of the first straight section 1712 can be chamfered to alleviate the yarn breakage caused by mechanical friction of the fiber bundle; the number of discharge holes 171 can be 1-50, preferably the same as the number of fiber bundles to be impregnated. In addition, handles 18 can be provided on both sides of the upper template 11 to facilitate the removal / covering of the upper template 11.

[0070] On the other hand, the utility model provides a melt impregnation mold system for manufacturing continuous fiber reinforced thermoplastic resin composite materials, such as Figure 5As shown, it includes a fiber pre-dispersing device 2, a combined melt impregnation die head 1 and a traction device (not shown) connected in sequence, the combined melt impregnation die head 1 is the combined melt impregnation die head 1 mentioned above, and the structure is the same as above, which will not be repeated here. The reference numeral 4 in the figure is a continuous fiber bundle.

[0071] The utility model discloses a melt impregnation die system, comprising a combined melt impregnation die head, which comprises an upper die plate and a lower die plate which are arranged relatively to each other, at least two detachable impregnation blocks are arranged below the upper die plate, each impregnation block is provided with a height adjustment device for adjusting the height of the impregnation block, and the adjustable range of the impregnation block height is from zero to the wave peak height value of the wavy flow channel, that is, the adjustable range of a single coating angle of a fiber bundle in the impregnation die is from 0° to the corresponding coating angle when the impregnation block is completely close to the lower die plate; compared with the impregnation roller in the prior art which can adjust the coating angle online, the single coating angle generated by the impregnation block in the utility model is significantly lower than the single coating angle generated by the impregnation roller, and the fiber bundle has no large fold angle when moving in the die, which can effectively reduce the probability of single filament breakage in the fiber bundle and thus meet the impregnation requirements of fiber bundles with a larger range of TEX values; the wavy impregnation block can also effectively reduce the volume of the die cavity, avoid the excessive resin from being accumulated in the die cavity for a long time due to the large volume of the die cavity, and cause the resin to be carbonized, thereby improving the yield rate of the impregnated silk product. The utility model is particularly suitable for bioactive glass fibers, and is suitable for the subsequent use of composite materials to manufacture orthopedic implants (such as bone nails, bone plates, etc.). It has a good impregnation effect and can accurately adjust the fiber bundle wrapping angle online, effectively improving the preparation performance of the composite material.

[0072] The fiber pre-dispersing device 2 can be in various forms that can be easily thought of by those skilled in the art. The present invention preferably adopts the following structural form:

[0073] like Figure 5 As shown, the fiber pre-dispersing device 2 includes at least three fixed shafts 21 (specifically, there may be 4-6, and the example in the figure shows 5) arranged at equal intervals in the horizontal direction, and each fixed shaft 21 is provided with a dispersion roller 22, the axis of the dispersion roller 22 is spaced a preset distance from the corresponding fixed shaft 21, and the dispersion roller 22 is connected to the corresponding fixed shaft 21 with the corresponding fixed shaft 21 as the center and the angle can be adjusted, and the fixed shaft 21 is provided with a dispersion roller angle adjustment device. In specific implementation, the dispersion roller 22 can be set with the corresponding fixed shaft 21 as the center through a rigid member, and the dispersion roller angle adjustment device can drive the fixed shaft 21 to rotate through a worm gear, and the fixed shaft 21 then drives the corresponding dispersion roller 22 to rotate through the rigid member. In this way, the position and angle of each dispersion roller 22 can be flexibly adjusted through the dispersion roller angle adjustment device, so the fiber pre-dispersing device 2 has a good dispersion effect on the continuous fiber bundle 4.

[0074] The diameter of the dispersion roller 22 can be 30mm-120mm, specifically 40mm-100mm, such as 50mm, 60mm, 70mm, etc., which can be flexibly selected according to usage requirements; the dispersion roller angle adjustment device can be provided with a compass 23 for recording the angle of the dispersion roller 22, so that the adjustable angle range of the dispersion roller 22 is 0°-360° and there is a compass scale to record the angle, and the dispersion roller 22 can rotate in a circle in the forward and reverse directions; the interior of the dispersion roller 22 can be provided with a heating rod and a thermocouple to preheat the continuous fiber bundle 4 and improve the subsequent impregnation and coating effect; the temperature of the dispersion roller 22 after heating can be 80℃-240℃, such as 100℃, 150℃, 200℃, etc.; the dispersion roller 22 can be provided with a pressure sensor for detecting the tension of the fiber bundle, and the corresponding tension can be read through the scale of the compass 23.

[0075] A cooling device (not shown) and a post-coating device (not shown) may also be connected in sequence between the combined melt impregnation die 1 and the traction device. Both the cooling device and the post-coating device may adopt existing technologies (such as the post-coating device shown in Figure 9 of the invention patent application CN114434672A "Impregnation mold, impregnation method and manufacturing system including an impregnation mold"), which will not be repeated here.

[0076] In the utility model, the thermoplastic resin used in the combined melt impregnation die head 1 and the rear coating device can be selected from polyethylene, polypropylene, nylon, polyetheretherketone, polyesters including polyethylene terephthalate, polylactic acid, and polyurethane; the molecular weight and viscosity of the thermoplastic resin used in the combined melt impregnation die head 1 are preferably lower than the molecular weight and viscosity of the thermoplastic resin used in the rear coating device. The traction speed range of the traction device can be 1m / min-100m / min, for example, 1m / min-20m / min.

[0077] For the above-mentioned melt impregnation mold system, the preparation process of preparing continuous fiber reinforced thermoplastic resin filaments with different diameters, glass fiber content and high viscosity value may specifically include the following steps:

[0078] (a) the fiber bundles untwisted by the untwisting device are alternately passed through the fiber pre-dispersing device 2, and the electric heating rod of the dispersion roller 22 is heated at the same time to perform pre-dispersing and pre-heating treatment on the fiber bundles, and the tension of the fiber bundles can be adjusted by adjusting the angle of the dispersion roller 22;

[0079] (b) the continuous fiber bundle treated in step (a) is passed through the yarn inlet 131 of the combined melt impregnation die 1 and out of the discharge hole 171 at the tail end of the die, and the thermoplastic resin is plasticized by the extruder and extruded into the mold cavity 13 of the combined melt impregnation die 1. After the upper mold plate 11 is covered, the single wrapping angle of the fiber bundle in the mold cavity 13 can be adjusted by the height adjustment device of the impregnation block 14, so as to improve the yarn spreading and impregnation of the fiber bundle in the mold cavity;

[0080] (c) pulling the fiber bundle impregnated with the thermoplastic molten resin in step (b) out of the impregnation mold (i.e., the combined melt impregnation die head 1) through a pulling device, and cooling and shaping it through a cooling device in the middle to obtain a continuous fiber reinforced thermoplastic resin wire with a smaller diameter;

[0081] (d) The plurality of composite wires with smaller diameters in step (c) are passed through a yarn guide plate and then passed into a post-coating device, and a thermoplastic resin is extruded into the post-coating device through an extruder to complete post-coating of the composite wires, thereby obtaining a continuous fiber reinforced thermoplastic resin wire with a higher viscosity value.

[0082] The resin wire prepared by the utility model is completed by two steps of impregnation and coating. The impregnation and coating processes can select the same or different resin grades according to the needs. The impregnation process can select a resin with relatively low molecular weight and viscosity to improve the impregnation effect, and the post-coating process stage can select a resin with relatively high molecular weight and viscosity to achieve the purpose of improving the surface quality of the wire, adjusting the fiber content and molecular weight and its distribution of the product, and improving the mechanics of the product.

[0083] In the above step (a), the continuous fiber is a bioactive glass fiber; the temperature of the dispersion roller 22 after heating is 80-240° C., preferably 100° C. The dispersion roller 22 can be adjusted in an angle range of 0°-360°, and the corresponding tension can be read by a compass scale.

[0084] In the above step (b), the thermoplastic resin is selected from polyethylene, polypropylene, nylon, polyetheretherketone, polyesters including polyethylene terephthalate, polylactic acid, and polyurethane. The adjustment range of a single wrap angle is 0°-90°, preferably 0°-60°. The aperture of the discharge hole 171 can be 0.1 mm-5 mm, preferably 0.3 mm-3.0 mm.

[0085] In the above step (c), the pulling speed of the pulling device ranges from 1 m / min to 100 m / min, preferably from 1 m / min to 20 m / min.

[0086] In summary, the utility model realizes quantitative setting of the degree of fiber pre-dispersion through the fiber pre-dispersion device, improves the repeatability of the process, and reduces the temperature difference between the fiber and the molten resin through the fiber preheating function, thereby improving the impregnation effect of the fiber in the mold cavity; the combined melt impregnation die head allows the covering angle to be adjusted online during fiber impregnation, improves the fiber spreading effect in the mold cavity, improves the fiber impregnation effect, and improves the interface bonding ability of the continuous fiber reinforced thermoplastic resin composite material.

[0087] Compared with the prior art, the utility model has the following advantages:

[0088] 1. The combined melt impregnation die head provided by the utility model is composed of multiple impregnation blocks with adjustable heights, which realizes the adjustable wrapping angle of the fiber bundle in the mold cavity, and the adjustment process is smooth to avoid the fiber bundle from breaking due to sudden changes in the wrapping angle. The wrapping angle of the existing equipment is fixed and cannot be adjusted during fiber impregnation, or the adjustment process is relatively violent, which is not friendly to the fiber bundle;

[0089] 2. In the utility model, the dispersion roller and the impregnation block are adjusted in height by rotating the compass with scale to change the fiber pre-dispersion tension and the fiber bundle impregnation covering angle. The tension value and the covering angle can be intuitively read and recorded through the compass scale, which greatly improves the repeatability of the continuous fiber reinforced thermoplastic composite material preparation process;

[0090] 3. The preparation method provided by the utility model completes the preparation of continuous fiber reinforced thermoplastic composite materials by three steps of fiber pre-dispersion and preheating, combined melt impregnation and post-coating, wherein the post-coating process improves the stability of the preparation process, while the traditional preparation method has a single equipment, a simple impregnation process, and poor fiber bundle dispersion and impregnation effects;

[0091] 4. The combined impregnation die head provided in the utility model is composed of multiple detachable modules, the size specifications can be adjusted according to actual needs, and the interchangeability is strong. During the production process, it can realize functions such as faster mold opening and closing and cleaning of broken yarns, and the process stability is high.

[0092] The utility model is described in detail below with reference to specific examples.

[0093] Embodiment 1 (without rear coating)

[0094] 1. The fiber pre-dispersing device 2 is composed of five fixed shafts 21 and angle-adjustable dispersing rollers 22 arranged at equal intervals. The diameter of the dispersing rollers 22 is 50 mm, and the distance between two adjacent dispersing rollers 22 is 100 mm.

[0095] 2. Combined impregnation die head 1, see Figure 4 , the resin flow channel is a wavy flow channel, the angle θ between the two broken lines on the first tooth surface 141 of the impregnation block 14 is designed to be 108.36°; the height of a single wave peak of each impregnation block 14 is 7.83mm; the height of the gap between the impregnation block 14 and the lower mold plate 12 is 7.27mm. The combined impregnation die head 1 has three impregnation blocks 14 whose heights can be adjusted by a height adjustment device. The corresponding relationship between the height adjustment of the impregnation block 14 and the mold covering angle and the total volume of the mold cavity is shown in Table 1:

[0096] Table 1

[0097]

[0098] illustrate:

[0099] ① For every 0.1mm drop of a single impregnation block, the corresponding single coating angle increases by 0.5 degrees. For a group of impregnation blocks, the coating angle increases by 3.0 degrees and the volume decreases by 0.068cm 3 ; That is, for every 0.1mm drop of a single impregnation block, the total wrap angle increases by 3.0 degrees, and the corresponding screw (i.e., height adjustment screw 15) rotates 36 degrees (M6 screw rotates 1 turn, and the pitch is 1mm); equivalent to the screw rotating 1 degree, the total wrap angle increases by 0.083 degrees;

[0100] ②The amount of material in the lower groove: 78.55*9*10*1.25 / 1000=8.84g.

[0101] Experiments show that the larger the wrapping angle, the better the impregnation effect, the better the corresponding glass fiber distribution of the wire and the interface bonding between the glass fiber and the resin, and the corresponding wire microstructure is as follows: Figure 6 When the total wrap angle exceeds 105.3° (for example, 109.1°), the glass fiber strength cannot withstand the friction resistance generated during the pultrusion process, and the filament cannot be prepared normally.

[0102] In order to solve the problem of insufficient mechanical properties of absorbable bone fixation devices (i.e. bone implants), the total mold coverage angle is increased from the perspective of equipment structural parameters. In the range of 0°-105.3°, the larger the coverage angle, the better the impregnation effect and the better the corresponding wire mechanical properties. The corresponding wire mechanical properties are shown in Table 2.

[0103] Table 2

[0104] Total mold coverage angle / ° 0 56.2 78.9 101.6 105.3 109.1 Maximum tensile load / N 450 580 719 1099 630 380

[0105] It can be seen that in the range of 0°-105.3°, the larger the total covering angle, the higher the mechanical properties of the wire.

[0106] In order to solve the problem of mismatch between the degradation rate of absorbable bone internal fixation devices and the tissue healing rate, the total coating angle is adjusted to achieve the goal of adjustable glass fiber content, characteristic viscosity value, molecular weight and distribution of the wire. Among them, within the range of 0°-105.3°, the degradation rate of the product can be adjusted by adjusting the total coating angle according to product needs. When the raw materials and other process parameters are consistent, the corresponding physical and chemical parameter values ​​are shown in Table 3.

[0107] Table 3

[0108]

[0109]

[0110] The degradation rate of the product is regulated from the perspective of the physical and chemical properties such as the glass fiber content of the silk material, the characteristic viscosity value, the molecular weight and its distribution. Under the same experimental environment, the same test standards and test methods, the influence of a single parameter on the degradation rate of the product is as follows: the lower the glass fiber content of the product, the slower the degradation rate; the higher the characteristic viscosity of the product, the slower the degradation rate; the higher the weight-average molecular weight of the product, the smaller the molecular weight distribution, and the slower the degradation rate. It can be seen that the total coverage angle is within the range of 0°-105.3°, and the adjustable range of the physical and chemical performance parameters is very wide. With the increase of the total coverage angle, the better the physical and chemical performance parameters of the product, the slower the degradation rate. The total coverage angle of the mold can be adjusted according to specific product requirements.

[0111] 3. The combined impregnation die head 1 also includes a disassembled and replaceable discharge plate 17 with different apertures. The discharge hole 171 consists of a conical section and a straight section. The conical section is connected to the end near the mold cavity, and the maximum opening is smoothly connected to the mold cavity 13. The angle of the conical section is 50° and the length is 5mm. The length of the straight section is 5mm and the aperture is 1mm. The discharge plate 17 includes two discharge holes 171.

[0112] The preparation process of preparing wires of different diameters using the above-mentioned melt impregnation mold system provided in this embodiment specifically includes the following steps:

[0113] (a) The untwisted 900 tex fiber bundles are alternately passed through the fiber pre-dispersing device 2, and the electric heating rod of the dispersion roller 22 is heated at the same time, and the preheating temperature is set to 120°C to perform pre-dispersing and pre-heating treatment of the fiber bundles. The tension of the fiber bundles can be adjusted by adjusting the angle of the dispersion roller 22, and the dispersion roller angle is set to 120°;

[0114] (b) the continuous fiber bundle treated in step (a) is passed through the yarn inlet 131 of the combined impregnation die 1 and is passed out from the discharge plate 17 at the tail end of the mold; after the thermoplastic resin is plasticized by the extruder, it is squeezed into the mold cavity 13 of the combined impregnation die 1, and after the upper mold plate 11 is covered, the single covering angle of the fiber bundle in the mold cavity 13 can be adjusted by the height adjustment screw 15 of the impregnation block 14 to improve the yarn spreading and impregnation of the fiber bundle in the mold cavity 13; the extruder feed section is set at 100°C, the plasticizing section is set at 220°C, the homogenizing section is set at 230°C, the extruder head is set at 240°C, and the combined melt impregnation die is set at 240°C. The continuous fiber bundle is dispersed and impregnated by the dispersion roller 22 and the impregnation block 14, and then pulled out through the 1.0 mm shaping hole;

[0115] (c) The fiber bundle impregnated with the thermoplastic molten resin in step (b) is pulled out of the impregnation mold by a pulling device, and is cooled and shaped by a cooling device in the middle to obtain a continuous fiber reinforced thermoplastic resin wire with a diameter of 0.85 mm.

[0116] In the above step (a), the continuous fiber is a bioactive glass fiber;

[0117] In the above step (b), the thermoplastic resin is polylactic acid with a weight average molecular weight of 137549; the total covering angle of the combined melt impregnation die is 68°;

[0118] In the above step (c), the pulling speed of the pulling device is 10m / min;

[0119] The prepared composite material has a glass fiber content of 70% and a weight average molecular weight of about 19000.

[0120] Embodiment 2 (including rear coating)

[0121] The design of the melt impregnation mold system in this embodiment is consistent with that in the first embodiment. The 0.85 mm wire prepared by the combined melt impregnation die head 1 in the first embodiment is used to prepare the 2.0 mm diameter wire. The specific operation is as follows:

[0122] The three composite wires with a diameter of 0.85 mm in step (c) of Example 1 are dispersed and placed on a yarn rack, and then inserted into the post-coating device. The temperature of the extruder and the post-coating die is set to 190°C. The resin used is polylactic acid of the same grade as in Example 1. The post-coating of the composite wire is completed by extruding the polylactic acid through the extruder, and the post-coating die is pulled out by a traction machine to obtain a continuous fiber reinforced thermoplastic resin wire with a higher viscosity value.

[0123] The yarn frame uses a spring to provide wire tension; the pulling speed of the pulling machine is set to 0.5m / min; the prepared composite material has a diameter of 2.0±0.05mm, a glass fiber content of 50%, and a weight average molecular weight of about 110000.

[0124] The microscopic morphology of the wire prepared by the conventional melt impregnation die head in the prior art and the wire prepared by the melt impregnation die system of the utility model is as follows: Figure 7 As shown, it can be seen that the interface bonding effect between the glass fiber and the resin of the composite material prepared by the utility model is significantly better than the interface bonding effect between the glass fiber and the resin in the wire material prepared by the conventional melt impregnation mold.

[0125] The above is a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A combined melt impregnation die head for manufacturing continuous fiber reinforced thermoplastic resin composite materials, characterized in that: The continuous fiber is a bioactive glass fiber, and the combined melt impregnation die head comprises an upper template and a lower template that are arranged opposite to each other, and a mold cavity is formed between the upper template and the lower template, wherein: At least two detachable impregnation blocks are provided below the upper template, and each impregnation block is provided with a height adjustment device for adjusting the height of the impregnation block; The lower surface of the impregnation block is provided with a first tooth surface, and the upper surface of the lower template is provided with a second tooth surface, so that a wavy resin flow channel is formed between the impregnation block and the lower template in the mold cavity, and the angle between two adjacent fold lines of the wavy structure of the resin flow channel is (0°, 180°); The mold cavity is provided with a yarn inlet at one end of the resin flow channel, and the mold cavity is provided with a material outlet at the other end of the resin flow channel.

2. The combined melt impregnation die head according to claim 1, characterized in that: The height adjustment device comprises a height adjustment screw, which is threadedly connected to the upper template, and the end of which passes through the upper template and is connected to the impregnation block. A compass with a scale is fixed on the height adjustment screw.

3. The combined melt impregnation die head according to claim 2, characterized in that: The upper template is threadedly connected with fastening screws above both ends of each impregnation block, and the ends of the fastening screws pass through the upper template and abut against the impregnation block; and / or, the second tooth surface on the lower template and the first tooth surface on the corresponding impregnation block have the same angle and height as the first tooth surface; And / or, the angle between two adjacent fold lines of the wavy structure of the resin flow channel is (45°, 180°).

4. The combined melt impregnation die head according to claim 1, characterized in that: The sides of the upper template and the lower template are provided with detachable discharge plates, the discharge hole is located on the discharge plate, and the discharge hole includes a first conical section and a first straight section in sequence.

5. The combined melt impregnation die head according to claim 4, characterized in that: The maximum opening of the first tapered section is smoothly connected to the mold cavity; And / or, the angle of the first tapered section is 20°-60°; And / or, the length of the first tapered section is 5 mm-20 mm; and / or, a smooth transition between the first tapered section and the first straight section; And / or, the length of the first straight section is 1 mm-20 mm; And / or, the first straight section is designed as a circular hole with a hole diameter ranging from 0.1 mm to 5 mm; And / or, the outlet of the first straight section is chamfered; and / or, the number of teeth on the first tooth surface and the second tooth surface are both 3-20; And / or, the tooth tops of the first tooth surface and the second tooth surface are both chamfered; And / or, the number of the discharge holes is 1-50, which is the same as the number of fiber bundles to be impregnated.

6. The combined melt impregnation die according to any one of claims 1 to 5, characterized in that: The single covering angle produced by a single tooth on one side of the first tooth surface and the second tooth surface for the fiber bundle to be impregnated is (0°, 30°), and the total covering angle produced by the combined melt impregnation die head for the fiber bundle to be impregnated is (0°, 105.3°).

7. The combined melt impregnation die head according to claim 6, characterized in that: The single covering angle of a single tooth on one side of the first tooth surface and the second tooth surface on the fiber bundle to be impregnated is 1°-15°, and the total covering angle of the combined melt impregnation die head on the fiber bundle to be impregnated is 56.2°-101.6°.

8. A melt impregnation mold system, characterized in that: The invention comprises a fiber pre-dispersing device, a combined melt impregnation die head and a traction device which are connected in sequence, wherein the combined melt impregnation die head is the combined melt impregnation die head as described in any one of claims 1-7.

9. The melt impregnation mold system according to claim 8, characterized in that: The fiber pre-dispersing device includes at least three fixed shafts arranged at equal intervals in the transverse direction, each fixed shaft is provided with a dispersion roller, the axis of the dispersion roller is spaced a preset distance from the corresponding fixed shaft, the dispersion roller is connected to the corresponding fixed shaft with the corresponding fixed shaft as the center and with an adjustable angle, and the fixed shaft is provided with a dispersion roller angle adjustment device.

10. The melt impregnation mold system according to claim 9, characterized in that: The diameter of the dispersion roller is 30 mm to 120 mm; And / or, the dispersion roller angle adjustment device is provided with a compass for recording the dispersion roller angle; And / or, a heating rod and a thermocouple are provided inside the dispersion roller, and the temperature of the dispersion roller after heating is 80° C.-240° C.; And / or, the dispersion roller is provided with a pressure sensor for detecting the tension of the fiber bundle; And / or, a cooling device and a post-coating device are sequentially connected between the combined melt impregnation die head and the traction device; And / or, the traction speed of the traction device ranges from 1 m / min to 100 m / min.

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