High-density regenerated carbon fiber particles and preparation method thereof

Abstract

The invention discloses a preparation method of high-density regenerated carbon fiber particles, which comprises the following steps: step S1, sizing treatment: regenerated carbon fibers are added into a sizing tank, the sizing tank is connected with a sizing liquid tank, and the carbon fibers are fully infiltrated in the sizing tank by controlling the flow rate of a sizing agent; s2, directional arrangement: arranging the carbon fibers subjected to sizing treatment on a directional conveyor belt to form carbon fiber layers with consistent directionality; step S3, carrying out compression roller extrusion; s4, granulation is conducted, specifically, the carbon fiber layer is divided into particles through a differential conveying crawler belt; step S5, drying and shaping; and step S6, packaging and storing. The short-cut regenerated carbon fibers are arranged in the direction of a track flow channel by controlling the flow speed of sizing agent liquid, and redundant sizing agent is removed through extrusion of a compression roller, so that a carbon fiber laying layer with high compactness and consistent directionality is formed. And the carbon fiber paving layer is pulled into particles by utilizing the adhesive force of the differential conveying track and the sizing agent, so that compact carbon fiber rice grains are formed.

Description

Technical Field

[0001] The invention relates to the technical field of carbon fiber reinforced plastic processing and modification, and in particular to high-density recycled carbon fiber particles and a preparation method thereof. Background Art

[0002] At present, there are three main ways to use carbon fiber in the field of carbon fiber reinforced plastic processing and modification, namely, adding continuous fiber bundles from the vent, adding short-cut carbon fiber with glue from the side feed, and mixing and feeding coated carbon fiber masterbatch. The continuous fiber bundle is added from the vent is the main form of the modified carbon fiber reinforced plastic granulation industry. Most of them are continuous fiber bundles added from the vent, but the difference between carbon fiber and glass fiber is that carbon fiber has very poor shear resistance, and the proportion of extremely short fibers is relatively high. The reinforcing effect of the material is limited, and the reinforcing effect of carbon fiber has not been fully exerted. The side feeding of short-cut carbon fiber with glue is to cut the continuous fiber into short-cut carbon fiber after impregnation. Compared with conventional fiber bundles with glue, it has stronger adhesion, but it still has the problem of fiber removal when it is slightly stirred or shaken. It is necessary to improve the side feeding and enhance the feeding capacity. Therefore, only a small number of factories use this process. The continuous carbon fiber bundle is coated and extruded and then pelletized to make a high-concentration carbon fiber masterbatch. The carbon fiber masterbatch has a lot of resin base, which usually affects the overall performance of reinforced plastics.

[0003] Due to the low amount of carbon fiber used in the field of modified plastics, large carbon fiber manufacturers such as Toray have not yet developed continuous carbon fiber types with special sizing agents. They all use general sizing agents or re-sizing after heating treatment and then chopped. This not only increases costs, but also because the carbon fiber is not dense, the bulk density of the chopped carbon fiber is small, generally only 200-300g / L, which requires a high feeding capacity for the equipment of the modification manufacturer. This is also one of the reasons that limit the large-scale promotion and application of carbon fiber reinforced thermoplastics. Therefore, it is urgent to solve the engineering and technical problems of low carbon fiber density and difficult feeding in the field of modified plastic processing. Summary of the invention

[0004] The object of the present invention is to provide a high-density recycled carbon fiber particle and a preparation method thereof, so as to solve one or more of the above-mentioned prior art problems.

[0005] The present invention provides a method for preparing high-density recycled carbon fiber particles, comprising the following steps:

[0006] Step S1, sizing treatment: adding the regenerated carbon fiber into a sizing tank, the sizing tank is connected to a sizing liquid tank, and the flow rate of the sizing agent is controlled so that the carbon fiber is fully infiltrated in the sizing tank;

[0007] Step S2, directional arrangement: the sizing treated carbon fibers are arranged on an directional conveyor belt to form a carbon fiber layer with consistent directionality;

[0008] Step S3, roller extrusion: the carbon fiber layer is extruded by a roller press;

[0009] Step S4, granulation: the carbon fiber layer is divided into granules by using a differential transmission track;

[0010] Step S5, drying and shaping;

[0011] Step S6, packaging and storage: packaging the dried carbon fiber particles.

[0012] In certain embodiments, the selection of the sizing agent in step S1 should take into account its adhesion to the carbon fiber and its effect on subsequent processes;

[0013] Preferably, the sizing agent is one of waterborne polyurethane, waterborne epoxy, waterborne polyamide and waterborne wax; the solid content of the sizing agent is 5%-15%.

[0014] In certain embodiments, the speed, angle and other parameters of the oriented conveyor belt in step S2 should be adjusted according to the characteristics of the carbon fiber and the process requirements;

[0015] Preferably, the speed of the directional conveyor belt is 0.1-1 m / s, and the angle between the directional conveyor belt and the ground is 15-45°.

[0016] In certain embodiments, the pressing roller machine in step S3 includes pressing roller 1, pressing roller 2 and pressing roller 3; the above-mentioned carbon fiber layer is pressed through pressing roller 1, pressing roller 2 and pressing roller 3 in sequence; pressing roller 1 squeezes the carbon fiber layer to remove most of the excess sizing agent, and forms a fiber ply with highly consistent fiber arrangement direction; pressing roller 2 controls the remaining amount of sizing agent in the fiber ply by adjusting the pressing roller pressure, accurately regulates the content of sizing agent in the product, and increases the density; the surface of pressing roller 3 has shallow grooves, which divides the fiber ply into strips, and increases the concentration of sizing agent by heating and extruding, thereby increasing its viscosity and increasing the density.

[0017] In certain embodiments, the roller pressure of the pressing roller 2 is 0.01-1 MPa. The roller pressure is adjusted according to the required sizing agent content. The greater the roller pressure, the less residual sizing agent in the carbon fiber.

[0018] In some embodiments, the heating temperature of the pressing roller 3 is 100-200°C, and the degree of adjustment is adjusted according to the amount of residual sizing agent in the carbon fiber and the speed of the oriented conveyor belt. The more residual sizing agent or the faster the oriented conveyor belt speed, the higher the required heating temperature.

[0019] Wherein: through the continuous extrusion of multiple pressing rollers (such as pressing roller 1, pressing roller 2, pressing roller 3), the excess sizing agent in the carbon fiber layer is removed, and the density of the carbon fiber is improved.

[0020] Parameters such as pressure and speed of the pressing roller should be adjusted according to the characteristics of carbon fiber and process requirements.

[0021] In certain embodiments, the speed difference of the differential conveyor belt during the pelletization process should be moderate to ensure uniformity and size consistency of the carbon fiber particles. In this process, the adhesion of the sizing agent plays a key role, which helps the formation and stability of the carbon fiber particles.

[0022] In certain embodiments, the drying temperature and time in step S5 should be adjusted according to the characteristics of the carbon fiber and the process requirements to ensure the dryness and stability of the carbon fiber particles;

[0023] Preferably, the drying temperature is 80-160° C. and the drying time is 1-4 h.

[0024] On the other hand, the present invention provides a high-density recycled carbon fiber particle, which is prepared by the following preparation method:

[0025] Step S1, sizing treatment: adding the regenerated carbon fiber into a sizing tank, the sizing tank is connected to a sizing liquid tank, and the flow rate of the sizing agent is controlled so that the carbon fiber is fully infiltrated in the sizing tank;

[0026] Step S2, directional arrangement: the sizing treated carbon fibers are arranged on an directional conveyor belt to form a carbon fiber layer with consistent directionality;

[0027] Step S3, roller extrusion: the carbon fiber layer is extruded by a roller press;

[0028] Step S4, granulation: the carbon fiber layer is divided into granules by using a differential transmission track;

[0029] Step S5, drying and shaping;

[0030] Step S6, packaging and storage: packaging the dried carbon fiber particles.

[0031] Beneficial effect: The present invention controls the flow rate of the sizing agent liquid to arrange the short-cut recycled carbon fiber along the direction of the track flow channel, and then removes the excess sizing agent through the pressure roller to form a carbon fiber ply with high density and consistent directionality. The carbon fiber ply is pulled into granules by using the adhesion of the differential transmission track and the sizing agent, and then dried to remove moisture to form dense carbon fiber rice grains. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below through embodiments.

[0033] Example 1

[0034] A high-density recycled carbon fiber particle is prepared by the following preparation method:

[0035] Step S1, sizing treatment: adding the regenerated carbon fiber into a sizing tank, the sizing tank is connected to the sizing tank, and the flow rate of the sizing agent is controlled to make the carbon fiber fully infiltrated in the sizing tank.

[0036] Wherein: the sizing agent is one of water-based polyurethane, water-based epoxy, water-based polyamide, and water-based wax; the solid content of the sizing agent is 5%%;

[0037] Step S2, directional arrangement: The sizing treated carbon fibers are arranged on a directional conveyor belt to form a carbon fiber layer with consistent directionality.

[0038] Among them: the speed of the directional conveyor belt is 0.1m / s, and the angle between the directional conveyor belt and the ground is 15°;

[0039] Step S3, roller extrusion: the carbon fiber layer is extruded by a roller press. Specifically,

[0040] The carbon fiber layer is sequentially squeezed through roller 1, roller 2 and roller 3; roller 1 squeezes the carbon fiber layer to remove most of the excess sizing agent and form a fiber ply with a highly consistent fiber arrangement direction; roller 2 adjusts the roller pressure to 0.01 MPa to control the remaining amount of sizing agent in the fiber ply, accurately adjust the content of sizing agent in the product, and increase the density; roller 3 has shallow grooves on its surface, which divides the fiber ply into strips, and increases the concentration of sizing agent by heating and squeezing, thereby increasing its viscosity and density, and controlling the heating temperature of roller 3 to be 100°C;

[0041] Step S4, granulation: the carbon fiber layer is divided into granules by using a differential transmission track;

[0042] Step S5, drying and shaping, the drying temperature is 80°C, and the drying time is 1h;

[0043] Step S6, packaging and storage: packaging the dried carbon fiber particles.

[0044] Example 2

[0045] A high-density recycled carbon fiber particle is prepared by the following preparation method:

[0046] Step S1, sizing treatment: adding the regenerated carbon fiber into a sizing tank, the sizing tank is connected to the sizing tank, and the flow rate of the sizing agent is controlled to make the carbon fiber fully infiltrated in the sizing tank.

[0047] Wherein: the sizing agent is one of water-based polyurethane, water-based epoxy, water-based polyamide, and water-based wax; the solid content of the sizing agent is 10%;

[0048] Step S2, directional arrangement: The sizing treated carbon fibers are arranged on a directional conveyor belt to form a carbon fiber layer with consistent directionality.

[0049] Among them: the speed of the directional conveyor belt is 0.5m / s, and the angle between the directional conveyor belt and the ground is 30°;

[0050] Step S3, roller extrusion: the carbon fiber layer is extruded by a roller press. Specifically,

[0051] The carbon fiber layer is sequentially squeezed through roller 1, roller 2 and roller 3; roller 1 squeezes the carbon fiber layer to remove most of the excess sizing agent and form a fiber ply with a highly consistent fiber arrangement direction; roller 2 adjusts the roller pressure to 0.5 MPa to control the remaining amount of sizing agent in the fiber ply, accurately regulates the content of sizing agent in the product, and increases the density; roller 3 has shallow grooves on its surface, which divides the fiber ply into strips, and increases the concentration of sizing agent by heating and squeezing, thereby increasing its viscosity and density, and controlling the heating temperature of roller 3 to be 150°C;

[0052] Step S4, granulation: the carbon fiber layer is divided into granules by using a differential transmission track;

[0053] Step S5, drying and shaping, the drying temperature is 120°C, and the drying time is 2.5h;

[0054] Step S6, packaging and storage: packaging the dried carbon fiber particles.

[0055] Example 3

[0056] A high-density recycled carbon fiber particle is prepared by the following preparation method:

[0057] Step S1, sizing treatment: adding the regenerated carbon fiber into a sizing tank, the sizing tank is connected to the sizing tank, and the flow rate of the sizing agent is controlled to make the carbon fiber fully infiltrated in the sizing tank.

[0058] Wherein: the sizing agent is one of water-based polyurethane, water-based epoxy, water-based polyamide, and water-based wax; the solid content of the sizing agent is 15%;

[0059] Step S2, directional arrangement: The sizing treated carbon fibers are arranged on a directional conveyor belt to form a carbon fiber layer with consistent directionality.

[0060] Among them: the speed of the directional conveyor belt is 1m / s, and the angle between the directional conveyor belt and the ground is 45°;

[0061] Step S3, roller extrusion: the carbon fiber layer is extruded by a roller press. Specifically,

[0062] The carbon fiber layer is sequentially squeezed through roller 1, roller 2 and roller 3; roller 1 squeezes the carbon fiber layer to remove most of the excess sizing agent and form a fiber ply with a highly consistent fiber arrangement direction; roller 2 controls the remaining amount of sizing agent in the fiber ply by adjusting the roller pressure to 1 MPa, accurately controls the content of sizing agent in the product, and increases the density; roller 3 has shallow grooves on its surface, divides the fiber ply into strips, and increases the concentration of sizing agent by heating and squeezing, thereby increasing its viscosity and increasing the density, and the heating temperature of roller 3 is controlled to be 200°C;

[0063] Step S4, granulation: the carbon fiber layer is divided into granules by using a differential transmission track;

[0064] Step S5, drying and shaping, the drying temperature is 160°C, and the drying time is 4 hours;

[0065] Step S6, packaging and storage: packaging the dried carbon fiber particles.

[0066] Equipment configuration and description

[0067] Sizing tank: used to hold sizing liquid and soak carbon fiber;

[0068] Oriented conveyor belt: with zigzag grooves, under the action of the sizing liquid flow, the carbon fibers are arranged along the groove direction;

[0069] Sizing tank: used to store and provide sizing liquid. The sizing liquid is poured into the directional conveyor belt through the sizing tank and then enters the sizing tank along the directional conveyor belt.

[0070] Pressing roller 1: used to squeeze the carbon fiber layer, remove excess sizing agent and improve density;

[0071] Pressing roller 2: Control the residual sizing agent content by controlling the pressure to improve the density;

[0072] Pressing roller 3: The layer is layered into simple strips through shallow grooves on the surface of the pressing roller, and the fiber layer is heated at the same time to make the fiber layer adhere and form;

[0073] Transverse grading conveyor belt: through the transverse speed difference, the simple strips between the layers are completely separated to form strip carbon fiber layers with uniform width;

[0074] Longitudinal grading conveyor belt: through continuous acceleration, the strip carbon fiber ply is gradually pulled apart to form granules;

[0075] Conveyor belt: used to transport carbon fiber particles from the drying room to the packaging box;

[0076] Drying room: used to dry carbon fiber particles and remove moisture and residual sizing agent;

[0077] Packaging box: used for storing and transporting carbon fiber pellets.

[0078] In summary, the present invention controls the flow rate of the sizing agent liquid to arrange the short-cut recycled carbon fibers along the direction of the track flow channel, and then removes the excess sizing agent through squeezing rollers to form a carbon fiber ply with high density and consistent directionality. The carbon fiber ply is pulled into granules by using the adhesion of the differential transmission track and the sizing agent, and then dried to remove moisture to form dense carbon fiber rice grains.

[0079] 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 high-density recycled carbon fiber particles, characterized in that: The following steps are involved: Step S1, sizing treatment: adding the regenerated carbon fiber into a sizing tank, the sizing tank is connected to a sizing liquid tank, and the flow rate of the sizing agent is controlled so that the carbon fiber is fully infiltrated in the sizing tank; Step S2, directional arrangement: the sizing treated carbon fibers are arranged on an directional conveyor belt to form a carbon fiber layer with consistent directionality; Step S3, roller extrusion: the carbon fiber layer is extruded by a roller press; Step S4, granulation: the carbon fiber layer is divided into granules by using a differential transmission track; Step S5, drying and shaping; Step S6, packaging and storage: packaging the dried carbon fiber particles.

2. The method for preparing high-density recycled carbon fiber particles according to claim 1, characterized in that: In step S1, the sizing agent is one of water-based polyurethane, water-based epoxy, water-based polyamide, and water-based wax; and the solid content of the sizing agent is 5%-15%.

3. The method for preparing high-density recycled carbon fiber particles according to claim 1, characterized in that: In step S2, the speed of the directional conveyor belt is 0.1-1 m / s, and the angle between the directional conveyor belt and the ground is 15-45°.

4. The method for preparing high-density recycled carbon fiber particles according to claim 1, characterized in that: In step S3, the pressing roller machine includes pressing roller 1, pressing roller 2 and pressing roller 3; the above-mentioned carbon fiber layer is pressed through pressing roller 1, pressing roller 2 and pressing roller 3 in sequence; pressing roller 1 squeezes the carbon fiber layer to remove most of the excess sizing agent, and forms a fiber ply with highly consistent fiber arrangement direction; pressing roller 2 controls the remaining amount of sizing agent in the fiber ply by adjusting the pressing roller pressure, accurately regulates the content of sizing agent in the product, and increases the density; the surface of pressing roller 3 has shallow grooves, which divides the fiber ply into strips, and increases the concentration of sizing agent by heating and extruding, thereby increasing its viscosity and increasing the density.

5. The method for preparing high-density recycled carbon fiber particles according to claim 4, characterized in that: The pressure of the pressure roller 2 is 0.01-1 MPa.

6. The method for preparing high-density recycled carbon fiber particles according to claim 4, characterized in that: The heating temperature of the pressure roller 3 is 100-200°C.

7. The method for preparing high-density recycled carbon fiber particles according to claim 1, characterized in that: In step S5, the drying temperature is 80-160° C. and the drying time is 1-4 hours.

8. A high-density recycled carbon fiber particle, which is prepared by the preparation method according to any one of claims 1 to 7.