Carbon fiber reinforced nylon wire for 3D printing and preparation method thereof

Abstract

The invention discloses a preparation method of a carbon fiber reinforced nylon wire for 3D printing, which comprises the following steps: a, carbon fiber surface treatment: carrying out surface treatment on chopped carbon fibers to obtain compatible modified carbon fibers; b, mixing the materials: stirring and mixing the nylon powder, the compatibility modified carbon fiber, the antioxidant and the light stabilizer; c, melting and mould pressing: uniformly paving the uniformly mixed powder on a mould pressing heating plate with a groove structure, performing hot pressing to melt the powder, and then transferring a mould to a cold press to be cooled into a thin round rod shape; d, stretching and forming: enabling the molten and cooled thin round rod to pass through a continuous heating cylinder stretching device; and e, cooling and shaping: feeding the stretched material into a cooling device for rapid cooling and shaping, and winding to obtain the nylon wire with the multidirectional random dispersion carbon fiber reinforcement characteristic. Through multidirectional random dispersion of the carbon fibers in a nylon matrix, the all-directional mechanical properties of a printed product are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing materials, and in particular to a carbon fiber reinforced nylon wire for 3D printing and a preparation method thereof. Background Art

[0002] 3D printing, also known as rapid prototyping technology or additive manufacturing technology, is a technology that uses metal powder or plastic and other adhesive materials to print layer by layer to manufacture objects of any shape based on digital model files. 3D printing technology is a major breakthrough in the world's manufacturing technology in the past 20 years. It is an integration of multidisciplinary technologies such as mechanical engineering, computer technology, numerical control technology, and material science. The most difficult and core technology of 3D printing is the development of printing materials.

[0003] Common 3D printing forming technologies include: SLA technology, FDM technology, SLS technology, LOM technology and 3DP technology, etc. Among them, FDM is the most common technology in 3D printing, which is widely used due to its advantages such as low operating cost, good printing quality, high forming accuracy, many types of materials and simple post-processing.

[0004] Carbon fiber has high strength, high specific modulus, low density, high temperature resistance, chemical corrosion resistance, low resistance, high thermal conductivity, radiation resistance, and excellent damping, shock absorption and noise reduction properties. Carbon fiber reinforced thermoplastic composites with carbon fiber as reinforcement and thermoplastic resin as matrix have the characteristics of light weight and high strength, reduced component weight, improved component efficiency, improved component reliability, and extended component life. They have advantages that metal materials cannot match.

[0005] There are also many patents about carbon fiber reinforced nylon wire. Patent No. CN 106700515A introduces a method for manufacturing carbon fiber reinforced nylon wire. However, when the wire is extruded through a single screw extruder, the fibers are arranged along the extrusion direction in the wire, resulting in fiber orientation. During 3D printing, the fiber direction is single when stacked and extruded layer by layer, resulting in poor radial mechanical properties. The continuous fiber reinforcement introduced by Patent No. CN 112757626A also has this problem. Patent No. CN 103951971 A introduces a laser sintered carbon fiber resin powder, but because the sintering process has high requirements on powder fluidity, the carbon fiber length is only about 200um, and graphite, flow aids, etc. are added, affecting the performance. Summary of the invention

[0006] To solve the above problems, the present invention proposes a carbon fiber reinforced nylon wire for 3D printing and a preparation method thereof. Through specific process steps, multi-directional random dispersion of carbon fibers in a nylon matrix is ​​achieved, thereby significantly improving the all-round mechanical properties of the printed products.

[0007] On the one hand, the present invention provides a method for preparing a carbon fiber reinforced nylon wire for 3D printing, comprising the following steps:

[0008] a. Carbon fiber surface treatment: Surface treatment of chopped carbon fiber to obtain compatible modified carbon fiber;

[0009] b. Material mixing: stirring and mixing the nylon powder, the compatible modified carbon fiber, the antioxidant and the light stabilizer;

[0010] c. Melt molding: Spread the mixed powder evenly on a molding heating plate with a groove structure, melt the powder by hot pressing, and then transfer the mold to a cold press to cool it into a thin round rod shape;

[0011] d. Stretching: The thin round rod after melting and cooling passes through a continuous heating cylinder stretching device to obtain a smooth, continuous and consistent wire;

[0012] e. Cooling and shaping: The stretched material is sent to a cooling device for rapid cooling and shaping, and then wound to obtain a nylon wire with multi-directional randomly dispersed carbon fiber reinforcement characteristics.

[0013] In certain embodiments, the chopped carbon fibers in step a have a length of 1-4 mm and a diameter of 5-7 μm.

[0014] In certain embodiments, the surface treatment process in step a is to first perform surface activation treatment and then apply the surface treatment agent; the surface activation treatment is a high-temperature oxidizing gas treatment at a temperature of 100-500°C for 1-30 min, and the oxidizing gas is one or a mixture of two or more gases selected from oxygen, ozone, and air; the surface treatment agent is one or a combination of two or more selected from a polyurethane dispersion, an ionized surfactant, a silane coupling agent, and a titanate coupling agent, and the treatment method is stirring and mixing in a high-speed mixer at a stirring speed of 300-900 r / min.

[0015] In certain embodiments, the nylon in step b is PA6, PA66, PA46, PA610, PA612, PA1010, PA1212 or PA1313, preferably PA66; the mass fraction of nylon powder is 50-95 parts, and the viscosity of nylon is 1-10 Pa·s.

[0016] In certain embodiments, the antioxidant in step b is diphenylamine, p-phenylenediamine and dihydroquinoline, thiodipropionic acid diester, 2,6-tert-butyl-4-methylphenol, bis(3,5-tert-butyl-4-hydroxyphenyl)sulfide, pentaerythritol tetrakis[β-(3,5-tert-butyl-4-hydroxyphenyl)propionate, didodecanol ester, didetradecyl alcohol ester or didecyl alcohol ester; the light stabilizer in step b is one or a mixture of two or more of hindered amines (HALS), benzophenones, benzotriazoles, triazines and salicylates.

[0017] Wherein: after the nylon powder is mixed with the compatible modified carbon fiber in step b, a resin mixture with anisotropic fiber orientation can be obtained; and the subsequent processing process will not destroy the fiber orientation.

[0018] In certain embodiments, in step c, the heating plate mold is divided into two parts, upper and lower parts, with semicircular grooves, which can be combined to form a round rod with a diameter of D.

[0019] In certain embodiments, in step c, the hot pressing temperature is 220-270°C, the time is 5-20 min, and the pressure is 0.5-5 MPa; the cooling temperature of the cold press is 15-25°C, the time is 15 min, and the pressure is 0.5-2 MPa.

[0020] In certain embodiments, in step c, the special groove structure of the molded heating plate is provided with a plurality of tiny grooves for guiding the random dispersion of the carbon fibers during the melting process.

[0021] In certain embodiments, in step d, the upper heating temperature of the heating cylinder is 150-200°C, the lower heating temperature is 180-300°C, the upper temperature is low, and the lower temperature is high. The heating cylinder is conical, and the upper diameter D: bottom diameter d = (1.1~1.3).

[0022] Among them: the function of the heating cylinder is to process the discontinuous thin round rods in step c into continuous wires and reel them up, while smoothing the appearance and improving printing stability.

[0023] In certain embodiments, the winding speed in step e is 0.5-10 m / min.

[0024] Among them: the winding speed is related to the stretching temperature and the upper and lower diameter ratio. The higher the stretching temperature, the faster the winding speed and the smaller the upper and lower diameter ratio.

[0025] In a second aspect, the present invention provides a carbon fiber reinforced nylon wire for 3D printing, which is prepared by the following method:

[0026] a. Carbon fiber surface treatment: Surface treatment of chopped carbon fiber to obtain compatible modified carbon fiber;

[0027] b. Material mixing: stirring and mixing the nylon powder, the compatible modified carbon fiber, the antioxidant and the light stabilizer;

[0028] c. Melt molding: Spread the mixed powder evenly on a molding heating plate with a groove structure, melt the powder by hot pressing, and then transfer the mold to a cold press to cool it into a thin round rod shape;

[0029] d. Stretching: The thin round rod after melting and cooling passes through a continuous heating cylinder stretching device to obtain a smooth, continuous and consistent wire;

[0030] e. Cooling and shaping: The stretched material is sent to a cooling device for rapid cooling and shaping, and then wound to obtain a nylon wire with multi-directional randomly dispersed carbon fiber reinforcement characteristics.

[0031] A carbon fiber reinforced wire is obtained by the preparation method of the present invention, and the distribution orientation of the carbon fiber in the wire is anisotropic, rather than conventional isotropic. The wire obtained by the prior art has carbon fiber directions oriented along the extrusion direction, and the performance is high in a single direction and extremely low in another direction. The carbon fiber obtained by the present invention has anisotropic distribution direction in the wire, and the product obtained by using the wire has a small performance difference in two directions; the fiber obtained by the present invention has a higher length and a more obvious improvement in mechanical properties.

[0032] Beneficial effects: The present invention achieves longer fiber length and multi-directional random dispersion of carbon fiber in nylon matrix through carbon fiber pretreatment and melt molding process, effectively solving the problem of poor radial mechanical properties caused by carbon fiber orientation in the prior art. The prepared carbon fiber reinforced nylon wire for 3D printing has excellent all-round mechanical properties, good processing performance and stable printing quality, and can be widely used in aerospace, automobile manufacturing, high-end equipment manufacturing and other fields, promoting the further development of 3D printing technology. DETAILED DESCRIPTION

[0033] The present invention is further described in detail below through embodiments.

[0034] Example 1

[0035] Follow these steps to prepare carbon fiber reinforced nylon filament for 3D printing:

[0036] a. Carbon fiber surface treatment: Select short-cut carbon fibers with a length of 1 mm and a diameter of 7 um, first perform high-temperature oxidation gas treatment (oxygen, temperature 300°C, time 10 min), and then apply surface treatment agent (combination of polyurethane dispersion and silane coupling agent, stirring and mixing in a high-speed mixer, stirring speed is 600 r / min).

[0037] b. Material mixing: 70 parts of nylon 66 powder (viscosity 3 Pa·s), 25 parts of treated carbon fiber, 2 parts of diphenylamine antioxidant, and 3 parts of hindered amine light stabilizer were stirred evenly in a high-speed mixer.

[0038] c. Melt molding: Spread the mixed powder evenly in the mold, and heat press at 250℃, 10min, and 3mpa. After molding, transfer to a cold press (20℃, 15min, and 1mpa) to cool into a thin round rod with a diameter of 2.6mm.

[0039] d. Stretching: The melted and cooled thin round rod is passed through a continuous heating cylinder stretching device, with an upper heating temperature of 150°C and a lower heating temperature of 220°C. The upper diameter D = 2.6 mm and the bottom diameter d = 2 mm to obtain a smooth, continuous and consistent wire.

[0040] e. Cooling and shaping: The stretched material is sent to a cooling device for rapid cooling and shaping, and then wound at a winding speed of 1m / min to obtain the final product.

[0041] Use this filament to print specimens in both horizontal and vertical directions to test tensile strength and modulus.

[0042] Example 2

[0043] The steps are basically the same as those in Example 1, except that:

[0044] -The carbon fiber length is 0.5mm and the diameter is 5um.

[0045] -The hot pressing temperature is 220℃ and the time is 20min.

[0046] -The heating temperature of the heating cylinder is adjusted to 180℃ at the top and 250℃ at the bottom, and the upper diameter D: bottom diameter d = 1.1.

[0047] - Winding speed 3m / min.

[0048] Example 3

[0049] The steps are basically the same as those in Example 1, except that:

[0050] -The carbon fiber length is 2mm and the diameter is 7um.

[0051] - The viscosity of nylon powder was adjusted to 2 Pa·s and the number of parts was 90 parts.

[0052] -The heating temperature of the heating cylinder is adjusted to 200°C at the top and 300°C at the bottom, and the top diameter D: bottom diameter d = 1.5.

[0053] - Winding speed 10m / min.

[0054] Comparative Example 1

[0055] The wire molding is modified by single screw extrusion molding, and the component ratio and fiber processing method are the same as in Example 1.

[0056] Comparative Example 2

[0057] No carbon fiber surface treatment was performed, and the remaining steps were the same as in Example 1. Results The compatibility of the carbon fiber with the nylon matrix was poor, and the mechanical properties of the printed product decreased.

[0058] Comparative Example 3

[0059] Without using a continuous heating cylinder stretching device, the thin round rod after melting and cooling is directly cut into short sections without stretching. As a result, the wire has an uneven appearance, poor continuity, and unstable printing quality.

[0060] The measured data of Examples 1-3 and Comparative Examples 1-3 are as follows:

[0061]

[0062]

[0063] Comparison conclusion between Example 1 and Comparative Example 1:

[0064] Compared with conventional nylon 66 wire, the carbon fiber reinforced nylon wire of Example 1 has significantly improved tensile strength in both the transverse and longitudinal printed strips. Compared with conventional extruded nylon 66 wire with 25% carbon fiber added, Example 1 significantly improves the transverse tensile strength (by 20.6%) while maintaining similar longitudinal tensile strength, indicating that the carbon fiber reinforced nylon wire of the present invention has more advantages in all-round mechanical properties.

[0065] Comparison conclusion between Example 2 and Comparative Example 2:

[0066] The carbon fiber in Example 2 has been surface treated to improve compatibility with the nylon matrix. Compared with Comparative Example 2 (without carbon fiber surface treatment), the tensile strength of the transverse printed strips in Example 2 increased by 13.8% (from 80.5 MPa to 91.6 MPa), and the tensile strength of the longitudinal printed strips increased significantly (from 93.4 MPa to 116.2 MPa). This shows that carbon fiber surface treatment is crucial to improving the overall mechanical properties of printed products.

[0067] Comparison conclusion between Example 3 and Comparative Example 3:

[0068] Example 3 uses a continuous heating cylinder stretching device to ensure the smooth appearance and continuity of the wire. Compared with Comparative Example 3 (which does not use a continuous heating cylinder stretching device), the tensile strength of the transverse printed strips of Example 3 is increased by 53.2% (from 57.1 MPa to 87.5 MPa), and the tensile strength of the longitudinal printed strips is also greatly improved (from 68.0 MPa to 128.3 MPa). This shows that the continuous heating cylinder stretching device has a significant effect on improving wire quality and printing stability.

[0069] Comparison conclusion between Example 1 and conventional nylon wire:

[0070] Compared with the unreinforced nylon 66 wire, the transverse tensile strength of Example 1 is increased by 53.0% (from 62.5 MPa to 95.6 MPa), and the longitudinal tensile strength is increased by 56.6% (from 71.6 MPa to 112.1 MPa).

[0071] In summary: The carbon fiber reinforced nylon wire for 3D printing and the preparation method thereof of the present invention successfully achieve multi-directional random dispersion of carbon fibers in the nylon matrix through innovative carbon fiber pretreatment, melt compression molding process and continuous heating cylinder stretching device, significantly improving the all-round mechanical properties of printed products. Compared with the prior art and conventional nylon wire, the wire of the present invention has significantly improved tensile strength and modulus, and has a wider application prospect and value.

[0072] The above description is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this field, several modifications and improvements can be made without departing from the creative concept of the present invention, and these should also be regarded as within the scope of protection of the invention.

Claims

1. A method for preparing carbon fiber reinforced nylon wire for 3D printing, characterized in that: The following steps are involved: a. Carbon fiber surface treatment: Surface treatment of chopped carbon fiber to obtain compatible modified carbon fiber; b. Material mixing: stirring and mixing the nylon powder, the compatible modified carbon fiber, the antioxidant and the light stabilizer; c. Melt molding: Spread the mixed powder evenly on a molding heating plate with a groove structure, melt the powder by hot pressing, and then transfer the mold to a cold press to cool it into a thin round rod shape; d. Stretching: The thin round rod after melting and cooling passes through a continuous heating cylinder stretching device to obtain a smooth, continuous and consistent wire; e. Cooling and shaping: The stretched material is sent to a cooling device for rapid cooling and shaping, and then wound to obtain a nylon wire with multi-directional randomly dispersed carbon fiber reinforcement characteristics.

2. The method for preparing carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: The chopped carbon fibers in step a have a length of 1-4 mm and a diameter of 5-7 μm.

3. The method for preparing a carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: The surface treatment process in step a is to first perform surface activation treatment and then apply the surface treatment agent; the surface activation treatment is a high-temperature oxidizing gas treatment at a temperature of 100-500° C. for 1-30 min, and the oxidizing gas is one or a mixture of two or more gases selected from oxygen, ozone, and air; the surface treatment agent is one or a combination of two or more selected from a polyurethane dispersion, an ionized surfactant, a silane coupling agent, and a titanate coupling agent, and the treatment method is stirring and mixing in a high-speed mixer at a stirring speed of 300-900 r / min.

4. The method for preparing a carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: In step b, the nylon is PA6, PA66, PA46, PA610, PA612, PA1010, PA1212 or PA1313, preferably PA66; the mass fraction of nylon powder is 50-95 parts, and the viscosity of nylon is 1-10 Pa·s.

5. The method for preparing carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: The antioxidant in step b is diphenylamine, p-phenylenediamine and dihydroquinoline, thiodipropionic acid diester, 2,6-tert-butyl-4-methylphenol, bis(3,5-tert-butyl-4-hydroxyphenyl)sulfide, pentaerythritol tetrakis[β-(3,5-tert-butyl-4-hydroxyphenyl)propionate, didodecanol ester, didetradecyl alcohol ester or didedecyl alcohol ester; the light stabilizer in step b is one or a mixture of two or more of hindered amines (HALS), benzophenones, benzotriazoles, triazines and salicylates.

6. The method for preparing carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: In step c, the heating plate mold is divided into two parts, upper and lower, with semicircular grooves, which can be combined to form a round rod with a diameter of D.

7. The method for preparing carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: In step c, the hot pressing temperature is 220-270° C., the time is 5-20 min, and the pressure is 0.5-5 MPa; the cooling temperature of the cold press is 15-25° C., the time is 15 min, and the pressure is 0.5-2 MPa.

8. The method for preparing carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: In step d, the heating temperature of the upper part of the heating cylinder is 150-200°C, and the heating temperature of the lower part is 180-300°C, and the upper temperature is low and the lower temperature is high. The heating cylinder is conical, and the upper diameter D: bottom diameter d = (1.1~1.3).

9. The method for preparing carbon fiber reinforced nylon wire for 3D printing according to claim 1, characterized in that: The winding speed in step e is 0.5-10m / min.

10. Carbon fiber reinforced nylon wire for 3D printing prepared by the preparation method according to any one of claims 1 to 9.

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