CN111761844A

CN111761844A - Continuous fiber composite material for 3D printing and preparation method and device thereof

Info

Publication number: CN111761844A
Application number: CN202010617151.7A
Authority: CN
Inventors: 李振; 王雁国; 茅伟华; 熊文治; 王立根
Original assignee: North Bridge New Material Technology Suzhou Co ltd
Current assignee: North Bridge New Material Technology Suzhou Co ltd
Priority date: 2020-06-30
Filing date: 2020-06-30
Publication date: 2020-10-13

Abstract

The application relates to a continuous fiber composite material for 3D printing and a preparation method and a device thereof, wherein the preparation device comprises a pre-dipping component for preparing a precursor of the continuous fiber composite material for 3D printing and a co-extrusion component for preparing the continuous fiber composite material for 3D printing, and the preparation method comprises the following steps: preheating a plurality of continuous fiber bundles, presoaking reaction liquid, combining yarns, heating the reaction liquid to react to generate a nylon polymer, and then cooling and drawing the continuous fibers to obtain a precursor; the precursor is co-extruded with a nylon melt through a co-extrusion die when being pulled, and the extruded composite material is cooled and pulled to obtain the continuous fiber composite material for 3D printing, so that the uniform dispersion of nylon in fiber bundles of the final finished composite material is ensured, the surface quality of the finished composite material is good, the wire diameter is stable, the continuous fiber composite material can be smoothly printed and formed in a continuous fiber 3D printer, the defects of a workpiece are greatly reduced, and the workpiece has good mechanical property and thermal stability.

Description

Continuous fiber composite material for 3D printing and preparation method and device thereof

Technical Field

The application belongs to the technical field of materials for 3D printing, and particularly relates to a continuous fiber composite material for 3D printing and a preparation method and device thereof.

Background

The 3D printing is a technology for manufacturing a three-dimensional product by adding materials layer by layer through a 3D printing device according to a designed 3D model, compared with the traditional manufacturing technology, the 3D printing does not need to manufacture a mould in advance, does not need to remove a large amount of materials in the manufacturing process, and can obtain a final product through complex casting, forging and welding processes, so that the structure optimization, the material saving and the energy saving can be realized in the production. Currently, 3D printing techniques are commonly used for new product development, rapid prototyping, single and small lot part manufacturing, manufacturing of complex shaped parts, design and manufacturing of molds, and the like. Among 3D printing technologies, Fused Deposition (FDM) is the most widely used 3D printing technology at present, and the materials applied in FDM process are typically polymers such as ABS, PLA, PA, PC, PVA, etc., which have the advantages of low melting point and easy molding, but have the disadvantages of low strength, difficult application in manufacturing actual carriers, and difficult satisfaction of multifunctional requirements under complicated conditions.

Although short fibers such as carbon fibers are used for reinforcing the mechanical property of the printing part in 3D printing, the mechanical property of the printing part is improved only in a limited way, the mechanical property is only slightly better than that of pure plastic, and due to the existence of the short fibers, the phenomena of obvious porosity and poor adhesion can be detected, so that the improvement space of the mechanical property of the composite material is limited. The continuous fiber has excellent mechanical, physical, corrosion-resistant, wear-resistant and fatigue-resistant performances, and has great application prospects in the fields of aerospace aviation, national defense and military, automobile racing, robots, medical treatment and the like. In recent years, various enterprises and scientific research institutions research and develop continuous fiber composite materials for 3D printing and printing processes thereof, but mature products are emerging.

At present, the main mode adopted for 3D printing by using continuous fiber reinforced thermoplastic resin is to directly introduce continuous fiber bundles into a nozzle of a printer, and the main defects of the technology are that the interface combination of continuous fibers and a thermoplastic resin matrix is poor, mainly because a flow channel in the nozzle of the 3D printer is short and short, the retention time of materials in the nozzle is short, and in addition, because enough forming pressure is lacked, the impregnation effect of the resin matrix on the fiber bundles is poor, and the reinforcing effect of the continuous fibers on composite products cannot be fully exerted. In the prior art, a process mode of separately carrying out fiber composite material preparation and printing exists, but the continuous fiber composite material prepared by the traditional method has the defects of poor dimensional stability and poor surface quality, is difficult to ensure smooth extrusion during printing, is not suitable for manufacturing parts with complex structures, and the prepared 3D printing piece has poor mechanical property and low heat-resistant temperature and cannot meet the requirements of industrial production.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the continuous fiber composite material for 3D printing and the preparation method and the device thereof are provided for solving the defects that the continuous fiber composite material prepared by the existing method is poor in dimensional stability and surface quality, and a 3D printed part prepared by using the continuous fiber composite material as a 3D printing material is poor in mechanical property and low in heat-resisting temperature.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a preparation method of a continuous fiber composite material for 3D printing comprises the following steps:

preheating a plurality of continuous fiber bundles, pre-dipping reaction liquid and yarn combination treatment, wherein the reaction liquid is caprolactam monomer and a catalyst;

heating reaction liquid soaked in the continuous fiber to react to generate a polymer, continuously removing water vapor in a reaction system in the heating reaction process of the reaction liquid, and then cooling and drawing the continuous fiber to obtain a precursor of the continuous fiber composite material for 3D printing;

and co-extruding the precursor of the continuous fiber composite material for 3D printing and a nylon melt through a co-extrusion die during traction, and cooling and traction the extruded composite material to obtain the continuous fiber composite material for 3D printing.

Preferably, the catalyst is a mixture of strong base, caprolactam salt and 2, 6-toluene diisocyanate, and the mass ratio of the strong base, the caprolactam salt and the 2, 6-toluene diisocyanate to the caprolactam monomer is preferably 1.5-2.5:0.5-1.5:3-5: 1000.

Preferably, the preheating temperature of the continuous fibers is 75-90 ℃; the pre-soaking temperature of the reaction liquid is preferably 75-90 ℃; the heating temperature for heating and polymerizing the reaction liquid is preferably 100-200 ℃, and the heating is preferably carried out in a gradient temperature rise mode; the temperature of the co-extrusion die is preferably 220-250 ℃.

Preferably, the continuous fiber bundles before the reaction liquid is presoaked are respectively scattered; preferably, the precursor of the continuous fiber composite material for 3D printing and the nylon material are dried before being co-extruded with the nylon melt through the co-extrusion die during drawing, and the drying temperature of the precursor of the continuous fiber composite material for 3D printing is preferably 100-135 ℃.

Preferably, the continuous fiber is at least one of carbon fiber, glass fiber, aramid fiber, basalt fiber and silicon carbide fiber; the nylon material is preferably extrusion grade PA12, extrusion grade PA11, a blend of PA12 and PA6 and a blend of extrusion grade PA11 and PA6, the content of PA6 in the blend is within 30%, and the nylon material preferably contains 0.2-0.3% of antioxidant.

The invention also provides the continuous fiber composite material for 3D printing prepared by the method.

The invention also provides a preparation device of the continuous fiber composite material for 3D printing, which comprises the following components: a prepreg assembly for preparing a continuous fiber composite precursor for 3D printing and a co-extrusion assembly for preparing a continuous fiber composite for 3D printing;

the prepreg assembly comprises a first unwinding drum, a preheater, a prepreg tank, a heating pipe, a first cooling tank, a first tractor and a first winding drum which are sequentially arranged along the running direction of continuous fibers; the first unwinding cylinder is used for placing continuous fibers before pre-dipping; the preheater is used for preheating a plurality of continuous fiber bundles; the pre-soaking tank is used for soaking the continuous fibers with the reaction liquid; the heating pipe is used for heating the reaction liquid soaked on the continuous fiber and is connected with a vacuum pump communicated with the interior of the heating pipe; the first cooling tank is used for cooling the continuous fiber bundle passing through the heating pipe, and the first winding drum is used for winding the continuous fiber composite material precursor for 3D printing passing through the first tractor;

the co-extrusion assembly comprises a second unwinding roller, a co-extrusion die, a second cooling tank, a second traction machine and a second winding roller which are sequentially arranged along the running direction of the continuous fibers; the first unwinding cylinder is used for placing the continuous fiber composite material precursor for 3D printing; the co-extrusion die is provided with a cavity for continuous fibers to pass through, and the co-extrusion die is provided with an extruder which is communicated with the cavity and is used for extruding material melt into the co-extrusion die; and the second cooling tank, the second tractor and the second winding drum are used for cooling, dragging and winding the continuous fibers passing through the co-extrusion die.

Preferably, roller groups are arranged between the first reel and the preheater and in the prepreg tank, each roller group comprises a plurality of groups of rollers which are arranged in parallel, and each group of rollers are arranged at intervals and used for scattering a plurality of continuous fibers respectively through the intervals.

Preferably, guide wheels for guiding the continuous fiber bundles before combination and the continuous fibers after combination are respectively arranged between the preheater and the prepreg tank and between the prepreg tank and the heating pipe; and an extrusion wheel which is provided with a die hole and used for the continuous fiber to pass through so as to remove redundant reaction liquid on the continuous fiber is also arranged between the pre-soaking tank and the heating pipe.

Preferably, the heating pipe is a heating sleeve, a heating pipe outer pipe and a heating pipe inner pipe for the continuous fibers to pass through from outside to inside in sequence, a cavity communicated with the heating pipe inner pipe is arranged in the heating pipe outer pipe, and the vacuum pump is communicated with the cavity of the heating pipe outer pipe.

The invention has the beneficial effects that:

the preparation method comprises the steps of utilizing a preparation device of the continuous fiber composite material for 3D printing containing the pre-dipping component and the co-extrusion component to preheat continuous fibers, pre-dipping reaction liquid and yarn combination treatment, heating the reaction liquid dipped in the continuous fibers to react to generate a nylon polymer to prepare a precursor of the continuous fiber composite material for 3D printing, and finally co-extruding the precursor of the continuous fiber composite material for 3D printing and a nylon melt to form a nylon surface layer. Therefore, the nylon in the fiber bundles of the final finished composite material is uniformly dispersed, the finished composite material is good in surface quality, stable in linear diameter and good in mechanical property and heat resistance, and can be smoothly printed and formed in a continuous fiber 3D printer, and the defects of a finished piece are greatly reduced.

1) Continuous fibers are pre-soaked by reaction liquid, particularly fiber bundles are fully stretched and dispersed when passing through a roller group and a preheater, so that low-viscosity small molecular monomers can be quickly and fully impregnated into each fiber, the fiber bundles and nylon can be uniformly and tightly combined after the reaction liquid is heated, reacted and polymerized, and possible defects in the composite material are reduced.

2) Caprolactam monomer can be polymerized rapidly in a heating pipe in an anionic polymerization mode, moisture carried in reaction liquid or generated in the reaction process is continuously removed by the heating pipe through vacuumizing, the polymerization degree of nylon in a precursor can be ensured, a layer of nylon material is added on the outer layer of the continuous fiber composite material precursor, the prepared composite material has a smooth surface, the adhesion between printing piece layers is good, and meanwhile, the abrasion of a wire inlet wheel and a printing nozzle of a 3D printer is reduced;

3) more time is needed in the nylon polymerization reaction process relative to the extrusion process of the wire rod, so the preparation process of the continuous fiber composite material is divided into the extrusion processes of preparing the composite material precursor and finally 3D printing the wire rod, a plurality of precursors can be simultaneously produced in the process of producing the composite material precursor, then only one extrusion production line is needed to produce the fiber composite material, the combination can be flexibly arranged, and the efficiency is improved.

4) The continuous fiber content is controllable, the composite material can be applied in a wide range from moderate fiber content to high fiber content, the composite material with high fiber content can be matched with other base materials to improve interlayer adhesion and surface detail forming, the composite material with medium fiber content can be directly printed and formed without improving adhesion between fiber layers by other base materials.

Drawings

The technical solution of the present application is further explained below with reference to the drawings and the embodiments.

Fig. 1 is a schematic structural view of a prepreg assembly of a continuous fiber composite material preparation apparatus for 3D printing according to example 1 of the present application;

FIG. 2 is a schematic view showing the structure of a co-extrusion module of an apparatus for manufacturing a continuous fiber composite material for 3D printing according to example 1 of the present application;

fig. 3 is a schematic cross-sectional view of a heating pipe of a continuous fiber composite material preparation apparatus for 3D printing according to example 1 of the present application;

the reference numbers in the figures are: 1-continuous fiber, 2-first unwinding roll, 3-preheater, 4-prepreg tank, 5-heating tube, 51-heating jacket, 52-heating tube outer tube, 53-heating inner tube, 6-first cooling tank, 7-first tractor, 8-first winding roll, 9-roller set, 10-guide wheel, 11-extrusion wheel, 12-mixer, 13-vacuum pump, 14-second unwinding roll, 15-co-extrusion die, 16-extruder, 17-second cooling tank, 18-second tractor, 19-second winding roll, and 20-diameter measuring instrument.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

In the description of the present application, it is to be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings for convenience in describing the present application and for simplicity in description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated in a particular manner, and are not to be considered limiting of the scope of the present application. Furthermore, the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the invention, the meaning of "a plurality" is two or more unless otherwise specified.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art through specific situations.

The technical solutions of the present application will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

Example 1

The embodiment provides a preparation facilities of continuous fibers combined material for 3D prints, includes: a prepreg assembly for preparing a continuous fiber composite precursor for 3D printing and a co-extrusion assembly for preparing a continuous fiber composite for 3D printing;

as shown in fig. 1, the prepreg assembly comprises a first unwinding reel 2, a preheater 3, a prepreg tank 4, a heating pipe 5, a first cooling tank 6, a first tractor 7 and a first winding reel 8 which are sequentially arranged along the running direction of continuous fibers 1; the first unwinding roller 2 is used for unwinding the continuous fiber 1 before presoaking; the preheater 3 is used for preheating the continuous fiber bundles 1; a mixer 12 for adding a reaction solution into the prepreg tank 4 is arranged on one side of the prepreg tank 4, and the prepreg tank 4 is used for impregnating the continuous fibers 1 with the reaction solution; the heating pipe 5 is used for heating the reaction liquid soaked on the continuous fiber 1, and the heating pipe 5 is connected with a vacuum pump 13 communicated with the inside of the heating pipe and used for removing gas substances (such as water vapor) generated in the reaction process of heating the reaction liquid; the first cooling tank 6 is used for cooling the continuous fiber bundle 1 passing through the heating pipe 7, and the first winding drum 8 is used for winding the continuous fiber composite material precursor for 3D printing passing through the first traction machine 7;

further, roller groups 9 are arranged between the first unwinding reel 2 and the preheater 3 and in the pre-soaking tank 6, each roller group 9 comprises a plurality of groups of rollers which are arranged in parallel, and each group of rollers is arranged at intervals and is used for respectively scattering a plurality of continuous fibers 1 through the intervals so as to enable the reaction liquid to fully soak the continuous fibers 1;

further, guide wheels 10 for guiding the plurality of continuous fibers 1 before combination and the continuous fiber bundles 1 after combination are respectively arranged between the preheater 3 and the pre-soaking tank 4 and between the pre-soaking tank 4 and the heating pipe 5; an extrusion wheel 11 which is provided with a die hole and used for the continuous fiber 1 to pass through so as to remove redundant reaction liquid on the continuous fiber 1 is also arranged between the pre-soaking tank 4 and the heating pipe 5;

further, the heating pipe 5 is sequentially provided with a heating sleeve 51, a heating pipe outer pipe 52 and a heating pipe inner pipe 53 for the continuous fiber 1 to pass through from outside to inside, a cavity communicated with the heating pipe inner pipe 53 is arranged in the heating pipe outer pipe 52, and the vacuum pump 13 is communicated with the cavity of the heating pipe outer pipe 52; as the vacuum is applied, the gas product (e.g., water vapor) generated during the reaction process will volatilize from the gap of the inner tube 53 of the heating tube to the outer tube 52 of the heating tube and be extracted away, so as to extract the gas product (e.g., water vapor) generated during the reaction process, which helps to proceed in the forward and reverse reaction direction, and reduce the bubble defect that the gas product (e.g., water vapor) may generate in the composite material.

As shown in fig. 2, the co-extrusion assembly comprises a second unwinding roll 14, a co-extrusion die 15, a second cooling tank 17, a diameter gauge 20, a second tractor 18 and a second winding roll 19 which are sequentially arranged along the running direction of the continuous fiber 1; the first unwinding roll 14 is used for unwinding a continuous fiber composite precursor for 3D printing; the co-extrusion die 15 is provided with a cavity for the continuous fiber 1 to pass through, and the co-extrusion die 15 is provided with an extruder 16 which is communicated with the cavity and is used for extruding material melt into the co-extrusion die 15; the second cooling tank 17, the diameter measuring instrument 20, the second tractor 18 and the second winding drum 19 are used for cooling, diameter measuring, traction and winding the continuous fiber 1 passing through the co-extrusion die 15.

Example 2

The present embodiment provides a method for preparing a continuous fiber composite material for 3D printing using the apparatus for preparing a continuous fiber composite material for 3D printing of embodiment 1, comprising the steps of:

4 bundles of Dongli carbon fibers (T300-3000) pass through a roller group 9, a preheater 3, a guide wheel 10 and a prepreg tank 4 (pass through the roller group 9 in the prepreg tank 4), reaction liquid is added into the prepreg tank through a mixer 12, the reaction liquid is caprolactam monomer and a catalyst, then 4 bundles of fibers pass through the guide wheel 10 and become a bundle, then pass through a die hole of an extrusion wheel 11 and the guide wheel 10, then pass through a heating pipe 5 to heat and polymerize the reaction liquid into a PA6 polymer, continuously vacuumize the heating pipe 5 through a vacuum pump 13 in the process, the composite material coming out of the heating pipe 5 is air-cooled and shaped through a first cooling tank 6, then passes through a first tractor 7 and is finally rolled on a first winding drum 8, and a precursor of the continuous fiber composite material for 3D printing is obtained, wherein:

the catalyst is a mixture of sodium hydroxide, sodium caprolactam and 2, 6-toluene diisocyanate, and the mass ratio of the sodium hydroxide, the sodium caprolactam, the 2, 6-toluene diisocyanate and the caprolactam monomer is 2:1:4: 1000; preheating temperature of continuous fiber: 82 ℃; temperature in mixer 12 and prepreg tank 4: 80 ℃; the inner diameter of the die hole of the extrusion wheel 11 is as follows: 0.92 mm; the heating pipe 5 is divided into 7 sections, each section is 40-50cm, and the heating temperature is respectively as follows: 100 ℃, 120 ℃, 140 ℃, 160 ℃, 180 ℃, 200 ℃, and the draw speed of the precursor of the continuous fiber composite material for 3D printing: 1 m/min.

Drying a precursor of the continuous fiber composite material for 3D printing at 120 ℃ for 8 hours, drying the extrusion grade PA12 until the moisture is less than 0.06%, then passing the precursor through the cavity of a co-extrusion die 15, supplying PA12 melt from an extruder 16, supplying the PA12 melt from the extruder 16 into the co-extrusion die 15, fusing the precursor with the continuous fiber 1 before demolding, reforming the fiber composite material, passing the precursor through a second cooling tank 17, a diameter measuring instrument 20 and a second tractor 18 under traction to form the continuous fiber composite material with the required wire diameter, and finally rolling the continuous fiber composite material on a second winding drum 19, wherein: temperature of the co-extrusion die: and (3) the aperture of a co-extrusion die neck ring at 230 ℃: 1.05 mm.

Example 3

This embodiment is different from embodiment 2 in that: dongli carbon fiber (M35JB-6000) was used, the mass ratio of the sodium hydroxide, sodium caprolactam and 2, 6-toluene diisocyanate to caprolactam monomer was 1.5:1.5:3:1000, the preheating temperature of the continuous fiber: 75 ℃; temperature in mixer 12 and prepreg tank 4: 75 ℃; drying a precursor of the continuous fiber composite for 3D printing at 100 ℃ for 10 hours; the inner diameter of the die hole of the extrusion wheel 11 is as follows: 0.93 m; the aperture of a 15-die of the co-extrusion die is as follows: 1.1 mm.

Example 4

This embodiment is different from embodiment 2 in that: the continuous fiber is fiber bundle of KEVLAR 29, 1670 dtex of DuPont company; the mass ratio of the sodium hydroxide, the sodium caprolactam, the 2, 6-toluene diisocyanate and the caprolactam monomer is 2.5:0.5:5:1000, and the preheating temperature of the continuous fiber is as follows: 80 ℃; temperature in mixer 12 and prepreg tank 4: 90 ℃; drying the precursor of the continuous fiber composite for 3D printing at 135 ℃ for 6 hours; the inner diameter of the die hole of the extrusion wheel 11 is as follows: 0.94 mm; the extruder 16 provides a nylon melt that is extrusion grade PA 11; the aperture of a 15-die of the co-extrusion die is as follows: 1.12mm, draw speed of continuous fiber composite precursor: 1.2 m/min.

Example 5

This embodiment is different from embodiment 2 in that: for the continuous fibers, 5 bundles of KEVLAR 49, 1270 dtex fiber bundles from dupont were used; the inner diameter of the PTFE die orifice is as follows: 0.94 mm. Preheating temperature of continuous fiber: 90 ℃; extruder 16 provides a nylon melt that is a blend of 80% PA12 and 20% PA 6; the aperture of a 15-die of the co-extrusion die is as follows: 1.1 mm; draw speed of continuous fiber composite precursor: 1.2 m/min.

Example 6

This embodiment is different from embodiment 2 in that: the continuous fibers used were 352A, 3000 dtex fiber bundles from Jushi corporation; preheating temperature of fiber bundle: 85 ℃; the extruder provided a nylon melt of 70% PA11 blended with 30% PA 6.

Example 7

This embodiment is different from embodiment 2 in that: as the continuous fibers, 2 bundles of Dongli carbon fibers (T300-3000) were used.

Comparative example 1

This comparative example differs from example 2 in that:

the continuous carbon fiber bundle does not pass through the roller group 9 (including the roller group 9 in the prepreg tank 4) and the preheater 3.

Comparative example 2

This comparative example differs from example 2 in that:

the heating pipe 5 is not evacuated by the vacuum pump 13.

Comparative example 3

This comparative example differs from example 2 in that:

the continuous fiber bundle does not go through the preparation process of the continuous fiber composite precursor for 3D printing.

Examples of effects

Effect example the continuous fiber composite materials prepared in examples 2 to 6 and comparative examples 1 to 3 were alternately printed with each layer of a sheet having a thickness of 4mm using a Mark Two continuous fiber 3D printer, using a continuous fiber composite material and an Onyx wire, wherein the printed layer height of the continuous fiber composite material was set to 0.4mm and the printed layer height of the Onyx wire was set to 0.2 mm. The continuous fiber composite material prepared in example 7 was directly printed into a plate having a thickness of 4mm using a Mark Two continuous fiber 3D printer.

Tensile specimens were machined and tested for tensile strength according to type A tensile specimen of Standard ISO 527, specimens of dimensions 80mm × 10mm × 4mm were machined and tested for unnotched impact strength according to Standard ISO 179, the heat distortion temperature of the specimens according to Standard ISO 75, the lengthwise direction of the cut specimens being in line with the direction of fiber printing, and the test results are given in the following table.

In the effect example, the tensile strength of the standard test only using the Onyx wire to print the sample strip is 58MPa, and the unnotched impact strength is 62KJ/m²The thermal deformation temperature is 137 ℃, and as shown in the effect data of the above-mentioned examples 2-6, the mechanical property and the thermal deformation temperature of a printed workpiece are obviously improved compared with those of a pure Onyx wire printing part by using the high-content continuous fiber composite material prepared by the invention to match with the Onyx wire; from example 7, it is seen that the composite material with moderate content of continuous fibers prepared by the present invention can be directly printed with test sample strips cut out from a sample plate without being matched with other wires, and also has good thermodynamic properties. As can be seen from comparative example 1, the continuous carbon fiber bundle can not be fully impregnated without passing through the roller group 9 (including the roller group 9 in the pre-impregnation tank 4) and the preheater 3, the mechanical property of the printed product is obviously reduced, the thermal deformation temperature is also reduced, and the cross section of the printed sample band shows that the inside of the fiber bundle is poorly impregnated; as can be seen from comparative example 2, the reaction solution is not vacuumized during the heating reaction polymerization process, which results in lower polymerization degree of PA6 in the precursor, obviously reduced mechanical property of the printed matter, reduced thermal deformation temperature, poor forming effect of the subsequent wire rod, exposed fiber of the wire rod and occurrence of carbonization point; as can be seen from comparative example 3, the preparation process of the continuous fiber composite precursor was not performed at all, and as a result, the prepared wire had fibers exposed, and the fiber bundles inside the printed sample bars were more difficult to be infiltrated, especially, the mechanical properties and the heat distortion temperature were severely lowered.

In light of the foregoing description of the preferred embodiments according to the present application, it is to be understood that various changes and modifications may be made without departing from the spirit and scope of the invention. The technical scope of the present application is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims

1. A preparation method of a continuous fiber composite material for 3D printing is characterized by comprising the following steps:

2. The method for preparing the continuous fiber composite material for 3D printing according to claim 1, wherein the catalyst is a mixture of a strong base, a caprolactam salt and 2, 6-toluene diisocyanate, and the mass ratio of the strong base, the caprolactam salt and the 2, 6-toluene diisocyanate to the caprolactam monomer is preferably 1.5-2.5:0.5-1.5:3-5: 1000.

3. The method for preparing a continuous fiber composite material for 3D printing according to claim 1 or 2, wherein the preheating temperature of the continuous fiber is 75-90 ℃; the pre-soaking temperature of the reaction liquid is preferably 75-90 ℃; the heating temperature for heating and polymerizing the reaction liquid is preferably 100-200 ℃, and the heating is preferably carried out in a gradient temperature rise mode; the temperature of the co-extrusion die is preferably 220-250 ℃.

4. The method for preparing a continuous fiber composite material for 3D printing according to any one of claims 1 to 3, wherein a plurality of continuous fiber bundles before the reaction liquid is presoaked are separately spread; preferably, the precursor of the continuous fiber composite material for 3D printing and the nylon material are dried before being co-extruded with the nylon melt through the co-extrusion die during drawing, and the drying temperature of the precursor of the continuous fiber composite material for 3D printing is preferably 100-135 ℃.

5. The method for preparing a continuous fiber composite material for 3D printing according to any one of claims 1 to 3, wherein the continuous fiber is at least one of carbon fiber, glass fiber, aramid fiber, basalt fiber, and silicon carbide fiber; the nylon material is preferably extrusion grade PA12, extrusion grade PA11, a blend of extrusion grade PA12 and PA6 and a blend of extrusion grade PA11 and PA6, wherein the content of PA6 in the blend is within 30%, and the nylon material preferably contains 0.2-0.3% of antioxidant.

6. A continuous fiber composite for 3D printing prepared by the method of any one of claims 1-5.

7. The utility model provides a preparation facilities of continuous fibers combined material for 3D prints which characterized in that includes: a prepreg assembly for preparing a continuous fiber composite precursor for 3D printing and a co-extrusion assembly for preparing a continuous fiber composite for 3D printing;

the pre-dipping component comprises a first reeling drum (2), a pre-heater (3), a pre-dipping tank (4), a heating pipe (5), a first cooling tank (6), a first tractor (7) and a first reeling drum (8) which are sequentially arranged along the running direction of the continuous fiber (1); the first unwinding roll (2) is used for unwinding the continuous fibers (1) before presoaking; the preheater (3) is used for preheating the continuous fiber bundles (1); the pre-soaking tank (4) is used for soaking the continuous fibers (1) with reaction liquid; the heating pipe (5) is used for heating the reaction liquid soaked on the continuous fiber (1), and the heating pipe (5) is connected with a vacuum pump (13) communicated with the inside of the heating pipe; the first cooling tank (6) is used for cooling the continuous fiber bundle (1) passing through the heating pipe (7), and the first winding drum (8) is used for winding the continuous fiber composite material precursor for 3D printing passing through the first traction machine (7);

the co-extrusion assembly comprises a second unwinding roll (14), a co-extrusion die (15), a second cooling tank (16), a second traction machine (18) and a second winding roll (19) which are sequentially arranged along the running direction of the continuous fiber (1); the first unwinding roll (14) is used for unwinding a continuous fiber composite precursor for 3D printing; the co-extrusion die (15) is provided with a cavity for the continuous fiber (1) to pass through, and the co-extrusion die (15) is provided with an extruder (16) which is communicated with the cavity and is used for extruding material melt into the co-extrusion die (15); the second cooling groove (17), the second traction machine (18) and the second winding drum (19) are used for cooling, drawing and winding the continuous fiber (1) passing through the co-extrusion die (15).

8. The apparatus for preparing continuous fiber composite material for 3D printing according to claim 7, wherein a roller group (9) is arranged between the first unwinding roll (2) and the preheater (3) and in the pre-dipping tank (6), the roller group (9) comprises a plurality of groups of rollers which are arranged in parallel, and each group of rollers is arranged at intervals and is used for respectively unwinding a plurality of continuous fibers (1) through the intervals.

9. The apparatus for preparing continuous fiber composite material for 3D printing according to claim 7 or 8, wherein guide wheels (10) for guiding the continuous fiber bundles (1) before combination and the continuous fibers (1) after combination are respectively arranged between the preheater (3) and the prepreg tank (4) and between the prepreg tank (4) and the heating pipe (5); and an extrusion wheel (11) which is provided with a die hole and used for allowing the continuous fiber (1) to pass through so as to remove redundant reaction liquid on the continuous fiber (1) is also arranged between the pre-soaking tank (4) and the heating pipe (5).

10. The device for preparing the continuous fiber composite material for 3D printing according to any one of claims 7-9, wherein the heating pipe (5) comprises a heating sleeve (51), an outer heating pipe (52) and an inner heating pipe (53) for the continuous fiber (1) to pass through in sequence from outside to inside, a cavity communicated with the inner heating pipe (53) is arranged in the outer heating pipe (52), and the vacuum pump (13) is communicated with the cavity of the outer heating pipe (52).