Flame-retardant regenerated carbon fiber modified engineering plastic particle and preparation method thereof

Abstract

The invention discloses a preparation method of flame-retardant regenerated carbon fiber modified engineering plastic particles. The preparation method comprises the following steps: S1, crushing; s2, under the nitrogen atmosphere condition, heating and cracking the carbon fiber broken blocks to obtain regenerated carbon fibers; s3, adding the regenerated carbon fiber and a flame retardant into an active agent solution, and performing uniform dispersion, surface treatment, filtration and drying to obtain activated regenerated carbon fiber; s4, dissolving resin into a solvent, adding the activated regenerated carbon fibers and a flame retardant, heating and stirring, and evaporating the solvent to obtain a pasty mixture; s5, processing and cutting the pasty mixture to obtain flame-retardant regenerated carbon fiber master batches; s6, drying the engineering plastic particles; and S7, mixing the engineering plastic particles with an auxiliary agent, adding the mixture from a main feed of a twin-screw extruder, adding the flame-retardant regenerated carbon fiber master batch through a side feed, and performing extrusion granulation through the extruder to obtain the modified engineering plastic particles. The modified engineering plastic particles have excellent flame retardance and mechanical properties.

Description

Technical Field

[0001] The invention relates to the technical field of recycling carbon fiber materials, and in particular to flame-retardant recycled carbon fiber modified engineering plastic particles and a preparation method thereof. Background Art

[0002] In recent years, carbon fiber reinforced materials (CFRP) have been widely used in aerospace, wind turbine blades, sports and leisure, automobiles, pressure vessels and other fields due to their high strength, high temperature resistance, friction resistance, electrical conductivity, thermal conductivity and corrosion resistance. A large amount of carbon fiber composite waste will be generated during the molding process of carbon fiber reinforced composite materials, and as the product ages or reaches the end of its service life, the carbon fiber waste will continue to increase.

[0003] At present, recycled carbon fiber is mainly recycled from wind power, aircraft manufacturing scraps and other carbon fiber with high regularity and strong directional consistency. After recycling, it is used in fields where fiber length requirements are not high, such as filament blending for fiber felt or short-cut modified plastics. There is no better recycling method for carbon fiber components with chaotic fiber directions such as woven carbon fiber cloth and carbon fiber felt. There are two problems with this type of recycled products. On the one hand, when carbon fiber is reinforced, it is woven in warp and weft or arranged in disorder. If the fibers are left at a certain length, they will clump. On the other hand, if the fibers are short, such as being ground into fiber powder with extremely small length and used for filling, the utilization value is low and the reinforcement effect is poor. Summary of the invention

[0004] In view of the above problems, the present invention proposes a flame retardant recycled carbon fiber modified engineering plastic particle and a preparation method thereof, aiming to efficiently recycle and utilize carbon fiber reinforced composite waste, especially for carbon fiber components with disordered fiber directions, and provide an effective recycling and reuse technical solution.

[0005] In one aspect, the present invention provides a method for preparing flame-retardant recycled carbon fiber modified engineering plastic particles, comprising the following steps:

[0006] S1. Crushing: crushing the carbon fiber reinforced material component into carbon fiber broken pieces;

[0007] S2, heating and cracking: heating and cracking the carbon fiber fragments under a nitrogen atmosphere to remove the resin portion to obtain regenerated carbon fiber;

[0008] S3, activation treatment: adding the regenerated carbon fiber and the flame retardant to the activator solution, uniformly dispersing and surface treating by ultrasonic vibration, filtering and drying to obtain activated regenerated carbon fiber;

[0009] S4, resin mixing: dissolving the resin in a solvent, adding the activated regenerated carbon fiber and the flame retardant, heating and stirring evenly, and evaporating the solvent to a paste-like mixture;

[0010] S5, granulation: processing the paste mixture into granules or sheets through a hot rolling mill, and then cutting and crushing to obtain flame-retardant recycled carbon fiber masterbatch;

[0011] S6, drying: drying the engineering plastic particles;

[0012] S7, mixed extrusion: the dried engineering plastic particles are mixed with additives, added through the main feed of a twin-screw extruder, and the flame-retardant recycled carbon fiber masterbatch is added through the side feed, and after extrusion and granulation through a twin-screw extruder, modified engineering plastic particles are obtained.

[0013] In certain embodiments, the carbon fiber reinforced material component in step S1 is a carbon fiber reinforced pultruded plate, a carbon fiber winding pressure tank, a short carbon fiber reinforced structure or a carbon fiber felt reinforced structure; and the diameter of the carbon fiber crushed pieces is 1-3 cm.

[0014] In certain embodiments, the heating cracking process in step S2 is heating at 600-650° C. for 60 minutes under a nitrogen atmosphere.

[0015] In certain embodiments, the active agent solution in step S3 is a coupling agent alcohol solution; the coupling agent is a silane coupling agent or a titanate coupling agent, and the weight ratio of the coupling agent to alcohol in the active agent solution is 1:100 to 5:100; the mass fraction of the regenerated carbon fiber is 30%-60%; the mass fraction of the flame retardant in step S3 is 30-60%.

[0016] In certain embodiments, the flame retardant in step S4 is one or a mixture of two or more of APP, ADP, and BDP; the resin in step S4 is one or a mixture of several of maleic anhydride grafted POE, EAA, EMA, and EBA; the solvent in step S4 is xylene solvent; the mass fraction of the resin is 10-20%; the mass content of the solvent in the paste mixture accounts for 10-20%.

[0017] Wherein: if the stirring is not performed in the solution in step S4 but in the form of powder or particles, the carbon fibers will be entangled and agglomerated.

[0018] In certain embodiments, in step S5, the surface of the hot rolling mill is coated with a Teflon coating, and the hot rolling temperature is 170-190°C.

[0019] In certain embodiments, the engineering plastic particles in step S6 are one or a mixture of two or more of PA, PC, PPS, and PET; the drying time in step S6 is 1-10 hours, and the drying temperature is 90-180°C.

[0020] In certain embodiments, the mass fraction of the engineering plastic particles in step S7 is 60-85%, the mass fraction of the auxiliary agent is 0.5-5%, and the mass fraction of the flame retardant recycled carbon fiber masterbatch is 15-40%; the auxiliary agent in step S7 is one or a mixture of two or more of an antioxidant, a light stabilizer, and a lubricant; the antioxidant is one or a mixture of two or more of aromatic amines, hindered phenols, thiodipropionic acid diesters, and phosphites; the light stabilizer is one or a mixture of two or more of salicylates, benzophenones, benzotriazoles, triazines, substituted acrylonitriles, oxamides, organic nickel compounds, and hindered amines (HAL); the lubricant is pentaerythritol stearate or a silicone polymer.

[0021] In certain embodiments, the base temperature of the twin-screw extruder in step S7 is 190-290° C., and the extruder speed is 200-600 r / min.

[0022] On the other hand, the present invention provides a flame retardant recycled carbon fiber modified engineering plastic particle, which has excellent flame retardant properties and mechanical properties; it is prepared by the following method:

[0023] S1. Crushing: crushing the carbon fiber reinforced material component into carbon fiber broken pieces;

[0024] S2, heating and cracking: heating and cracking the carbon fiber fragments under a nitrogen atmosphere to remove the resin portion to obtain regenerated carbon fiber;

[0025] S3, activation treatment: adding the regenerated carbon fiber and the flame retardant to the activator solution, uniformly dispersing and surface treating by ultrasonic vibration, filtering and drying to obtain activated regenerated carbon fiber;

[0026] S4, resin mixing: dissolving the resin in a solvent, adding the activated regenerated carbon fiber and the flame retardant, heating and stirring evenly, and evaporating the solvent to a paste-like mixture;

[0027] S5, granulation: processing the paste mixture into granules or sheets through a hot rolling mill, and then cutting and crushing to obtain flame-retardant recycled carbon fiber masterbatch;

[0028] S6, drying: drying the engineering plastic particles;

[0029] S7, mixed extrusion: the dried engineering plastic particles are mixed with additives, added through the main feed of a twin-screw extruder, and the flame-retardant recycled carbon fiber masterbatch is added through the side feed, and after extrusion and granulation through a twin-screw extruder, modified engineering plastic particles are obtained.

[0030] Beneficial effects: The present invention realizes the effective recycling and reuse of carbon fiber components with disordered fiber directions through a series of innovative process steps. Flame-retardant regenerated carbon fiber masterbatch is prepared by steps such as removing resin by heating and cracking, surface treatment of activated regenerated carbon fiber, resin mixing and granulation. Furthermore, the flame-retardant regenerated carbon fiber masterbatch is mixed with engineering plastics, extruded and granulated by a twin-screw extruder, and modified engineering plastic particles with flame-retardant properties are obtained. This method not only improves the utilization rate of carbon fiber waste, but also the prepared modified engineering plastic particles have excellent flame retardant properties and mechanical properties, broadening the application field of recycled carbon fibers. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below through embodiments.

[0032] Example 1

[0033] Preparation of flame retardant recycled carbon fiber masterbatch:

[0034] 1. Crushing: Select carbon fiber reinforced pultruded board as the carbon fiber reinforced material component and crush it into carbon fiber broken blocks with a diameter of 1.5 cm by a crusher.

[0035] 2. Heating pyrolysis: Place the carbon fiber fragments in a nitrogen atmosphere and heat at 630°C for 60 minutes to remove the resin portion to obtain regenerated carbon fiber.

[0036] 3. Activation treatment: Add recycled carbon fiber (mass fraction of 40%) and APP flame retardant (mass fraction of 40%) to a silane coupling agent alcohol solution (the weight ratio of coupling agent to alcohol is 3:100), uniformly disperse and surface treat by ultrasonic vibration, and obtain activated regenerated carbon fiber after filtration and drying.

[0037] 4. Resin mixing: dissolve maleic anhydride grafted POE resin (mass fraction is 20%) in xylene solvent, add activated recycled carbon fiber and flame retardant, heat and stir evenly, evaporate the xylene solvent to a paste mixture, in which the solvent content accounts for 15%.

[0038] 5. Granulation: The paste mixture is processed into granules by a double-roll hot rolling mill (hot rolling temperature is 180°C, and the surface is coated with Teflon coating), and then cut and crushed to obtain flame-retardant recycled carbon fiber masterbatch.

[0039] Preparation of flame retardant recycled carbon fiber modified engineering plastics:

[0040] 6. Drying: Dry the PA engineering plastic particles for 5 hours at a temperature of 120°C.

[0041] 7. Mixed extrusion: Mix the dried PA66 (Shenma EPR27) engineering plastic (70% by mass) with an antioxidant (2% by mass), a light stabilizer (2% by mass) and a lubricant (1% by mass), and add them through a twin-screw extruder as the main feed. Add the flame-retardant recycled carbon fiber masterbatch (25% by mass) through a side feed. The base temperature of the twin-screw extruder is 280°C and the speed of the extruder is 400r / min. After extrusion and granulation by a twin-screw extruder, modified engineering plastic particles are obtained.

[0042] Example 2

[0043] Similar to Example 1, but the mass fraction of recycled carbon fiber is adjusted to 60%, the flame retardant is ADP, and the engineering plastic is PC (Formosa Plastics IR2200), the drying temperature and time are adjusted to 110°C and 2 hours respectively, and the mass fraction of flame retardant recycled carbon fiber masterbatch is 20%.

[0044] Example 3

[0045] Similar to Example 1, but the source of the recycled carbon fiber is changed to a pressure tank for carbon fiber winding molding, the heating pyrolysis temperature is 650°C, the resin is a mixture of EMA and EAA with a mass fraction of 15%, and the engineering plastic PET (Yuanfang Shanghai / CB-602A) and the mass fraction of the flame retardant recycled carbon fiber masterbatch are 40%.

[0046] Comparative Example 1

[0047] Similar to Example 1, the recycled carbon fibers are directly mixed with the resin without performing the activation treatment step.

[0048] Comparative Example 2

[0049] Similar to Example 1, but the heating pyrolysis temperature was lowered to 500°C, resulting in incomplete resin removal.

[0050] Comparative Example 3

[0051] Similar to Example 1, in step S4, no solvent is used to dissolve the resin, and the resin is directly mixed and stirred.

[0052] The modified granules were injection molded into test specimens for tensile, oxygen index and fiber content performance tests.

[0053] Note: The fiber content test method is to cut the injection molded specimen into small pieces, weigh a sample with a mass of M, put it into a heating device, pyrolyze it at 500℃ for 2h under a nitrogen atmosphere, and weigh the remaining fiber mass m after cooling to room temperature. Fiber content = m / M*100%.

[0054] The test results are shown in the following table:

[0055]

[0056] Result analysis:

[0057] The modified engineering plastic particles in Examples 1-3 all exhibited good flame retardancy and mechanical properties, which demonstrated the effectiveness of the method of the present invention.

[0058] Since comparative example 1 is not activated, the bonding force between the recycled carbon fiber and the resin is weak, which may lead to a decrease in the mechanical properties of the modified engineering plastics.

[0059] In Comparative Example 2, the resin is not completely removed, which may result in the presence of impurities in the modified engineering plastics, affecting their performance.

[0060] In Comparative Example 3, the fibers agglomerated during stirring and could not be evenly distributed, resulting in lower performance and a large deviation in the fiber content test.

[0061] In summary: the flame-retardant recycled carbon fiber modified engineering plastic particles and the preparation method thereof provided by the present invention realize the efficient recovery and reuse of carbon fiber waste through a series of innovative process steps. At the same time, the prepared modified engineering plastic particles have excellent flame retardant properties and mechanical properties, providing a new way for the reuse of carbon fiber.

[0062] 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 flame-retardant recycled carbon fiber modified engineering plastic particles, characterized in that: The following steps are involved: S1. Crushing: crushing the carbon fiber reinforced material component into carbon fiber broken pieces; S2, heating and cracking: heating and cracking the carbon fiber fragments under a nitrogen atmosphere to remove the resin portion to obtain regenerated carbon fiber; S3, activation treatment: adding the regenerated carbon fiber and the flame retardant to the activator solution, uniformly dispersing and surface treating by ultrasonic vibration, filtering and drying to obtain activated regenerated carbon fiber; S4, resin mixing: dissolving the resin in a solvent, adding the activated regenerated carbon fiber and the flame retardant, heating and stirring evenly, and evaporating the solvent to a paste-like mixture; S5, granulation: processing the paste mixture into granules or sheets through a hot rolling mill, and then cutting and crushing to obtain flame-retardant recycled carbon fiber masterbatch; S6, drying: drying the engineering plastic particles; S7, mixed extrusion: the dried engineering plastic particles are mixed with additives, added through the main feed of a twin-screw extruder, and the flame-retardant recycled carbon fiber masterbatch is added through the side feed, and after extrusion and granulation through a twin-screw extruder, modified engineering plastic particles are obtained.

2. The method for preparing a flame-retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: The carbon fiber reinforced material component in step S1 is a carbon fiber reinforced pultruded plate, a carbon fiber winding pressure tank, a short carbon fiber reinforced structural part or a carbon fiber felt reinforced structural part; the diameter of the carbon fiber crushed pieces is 1-3 cm.

3. The method for preparing a flame-retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: The heating cracking process in step S2 is heating at 600-650° C. for 60 minutes under a nitrogen atmosphere.

4. The method for preparing a flame-retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: The active agent solution in step S3 is a coupling agent alcohol solution; the coupling agent is a silane coupling agent or a titanate coupling agent, and the weight ratio of the coupling agent to the alcohol in the active agent solution is 1:100 to 5:100; the mass fraction of the regenerated carbon fiber is 30%-60%; the mass fraction of the flame retardant in step S3 is 30-60%.

5. The method for preparing a flame-retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: The flame retardant in step S4 is one or a mixture of two or more of APP, ADP, and BDP; the resin in step S4 is one or a mixture of several of maleic anhydride grafted POE, EAA, EMA, and EBA; the solvent in step S4 is xylene solvent; the mass fraction of the resin is 10-20%; the mass content of the solvent in the paste mixture accounts for 10-20%.

6. The method for preparing a flame retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: In step S5, the surface of the hot rolling mill is coated with a Teflon coating, and the hot rolling temperature is 170-190°C.

7. The method for preparing flame-retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: The engineering plastic particles in step S6 are one or a mixture of two or more of PA, PC, PPS, and PET; the drying time in step S6 is 1-10 hours, and the drying temperature is 90-180°C.

8. The method for preparing flame-retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: The mass fraction of the engineering plastic particles in step S7 is 60-85%, the mass fraction of the auxiliary agent is 0.5-5%, and the mass fraction of the flame-retardant recycled carbon fiber masterbatch is 15-40%; the auxiliary agent in step S7 is one or a mixture of two or more of an antioxidant, a light stabilizer, and a lubricant; the antioxidant is one or a mixture of two or more of aromatic amines, hindered phenols, thiodipropionic acid diesters, and phosphites; the light stabilizer is one or a mixture of two or more of salicylates, benzophenones, benzotriazoles, triazines, substituted acrylonitriles, oxamides, organic nickel compounds, and hindered amines (HAL); the lubricant is pentaerythritol stearate or a silicone polymer.

9. The method for preparing flame-retardant recycled carbon fiber modified engineering plastic particles according to claim 1, characterized in that: In step S7, the base temperature of the twin-screw extruder is 190-290° C., and the speed of the extruder is 200-600 r / min.

10. The flame retardant recycled carbon fiber modified engineering plastic particles prepared by the preparation method according to any one of claims 1 to 9, characterized in that: The flame retardant recycled carbon fiber modified engineering plastic particles have excellent flame retardant properties and mechanical properties.

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