JP2018016695A - Method for treating carbon fiber reinforced plastic and method for producing fuel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing method of a carbon fiber reinforced plastic capable of making crushability good while keeping recovery rate high when used as a fuel and capable of suppressing scattering of processed articles after a heat treatment.SOLUTION: There is provided a processing method of a carbon fiber reinforced plastic by conducting a heat treatment according to following conditions 1 and 2 on a mixture obtained by mixing the carbon fiber reinforced plastic and a thermoplastic resin or a material containing the thermoplastic resin. (Condition 1) Heating temperature of the mixture is 250 to 500°C. (Condition 2) Heating time is set within a range of 10 min. to 12 hr. depending on the heating temperature.SELECTED DRAWING: None

Description

  The present invention relates to a treatment method for reducing the mechanical strength of a carbon fiber reinforced plastic, and a fuel production method using a carbon fiber reinforced plastic obtained by treating the carbon fiber reinforced plastic with the treatment method.

  Carbon fiber reinforced plastic (hereinafter also referred to as “CFRP”) is lightweight and excellent in mechanical strength such as high strength and high elasticity, so it is small in size such as tennis rackets, golf club shafts, fishing rods, etc. To large-sized products for industrial use such as automobiles and aircraft, and is used in large quantities. Not only those products but also defective products generated in the manufacturing process are added, and it is considered that the amount of CFRP discarded in the future will continue to increase, and it is required to effectively use these as resources.

  As a recycling technique, various techniques for separating and recovering carbon fibers from CFRP waste have been studied. For example, in Patent Document 1, as a treatment method of CFRP, carbon fiber reinforced plastic is not burned in a gas atmosphere in which the oxygen concentration is in the range of 3 to 18% by volume and the temperature is in the range of 300 to 600 ° C. It has been proposed to treat, pyrolyze the plastic and recover the carbon fiber. However, even if carbon fibers are recovered from waste, the fibers are often shortened or the strength is reduced. Therefore, material recycling and chemical recycling are difficult, and there are many final landfills. However, landfill disposal will become difficult in the future due to securing landfill sites and strengthening regulations.

  After all, thermal recycling using CFRP as a fuel is an effective method because it can achieve both recycling and final disposal. One method is to use fuel in cement manufacturing processes. This means that it is possible to cope with an increase in the processing amount, that it can be processed even when waste other than CFRP is mixed, that it can handle CFRP of various shapes and compositions, and that no waste is generated by the processing. This is an effective recycling method.

  Patent Document 2 discloses a carbon in which waste plastic containing carbon fiber is supplied to a cement kiln and exhaust gas generated by performing a combustion process is supplied to a dust collector to collect dust in the exhaust gas. In the incineration processing method for waste plastics containing fibers, the waste plastics containing carbon fibers are pulverized so as to have an average particle diameter of 3 mm or less, and supplied to a position where the internal temperature of the cement kiln is 1200 ° C. or more. It is described that it can be used as a part of fuel in a cement manufacturing apparatus without performing fiber separation.

JP-A-6-99160 JP 2007-131463 A

  However, in the processing method described in Patent Document 2, since CFRP is excellent in mechanical strength, the grinder is severely worn and a large amount of grinding energy is required. Therefore, the method of grinding CFRP to 3 mm or less is Not realistic. That is, CFRP is difficult to crush and finely pulverize because carbon fiber and resin have high integrity and high strength.

  Moreover, in the processing method described in Patent Document 1, the recovery rate when used as fuel was low. Here, the recovery rate refers to the ratio of the calorific value of CFRP after heating to the calorific value of CFRP before heating. More specifically, instead of comparing the unit calorific value (J / g) obtained by measurement, the material balance of the calorific value taking into account the weight before treatment and the weight after treatment is shown. That is, the recovery rate is obtained by the following formula.

Recovery rate = unit calorific value after treatment x recovered weight / unit calorific value before treatment x treated weight Note that in this specification, the calorific values of carbon and resin are considered to be approximately equal, and the residual rate after heating ≒ recovery rate It is said.

  On the other hand, a processed product obtained by heat-treating CFRP has a small bulk specific gravity and easily scatters. Therefore, when the processed product is conveyed by a belt conveyor or the like, there is a problem that the processed product is easily slid and scattered. Furthermore, if the carbon fiber is separated and separated, the carbon fiber is a high-strength fiber, which may adversely affect the human body, causing problems such as poor charging in the electrostatic precipitator, and the performance of the bag filter. There was a risk of a decrease.

  An object of the present invention is to provide a carbon fiber reinforced plastic processing method capable of improving the pulverization property while maintaining a high recovery rate when used as a fuel, and capable of suppressing scattering of a processed product after heat treatment, and An object of the present invention is to provide a method for producing a fuel capable of effectively using carbon fiber reinforced plastic as a waste material as a fuel.

  The present inventors mix and heat a thermoplastic resin or the like in CFRP, and even when carbon fibers are produced, they adhere to the thermoplastic resin, become entangled, or are coated, thereby suppressing scattering. As a result, the present invention has been completed.

The method for treating a carbon fiber reinforced plastic according to the present invention comprises subjecting a mixture obtained by mixing at least a carbon fiber reinforced plastic and a thermoplastic resin or a material containing a thermoplastic resin to a heat treatment according to the following conditions 1 and 2. It is characterized by giving.
(Condition 1) The heating temperature of the mixture is set to 250 to 500 ° C.
(Condition 2) The heating time is set within a range of 10 minutes to 12 hours according to the heating temperature.

  In the carbon fiber reinforced plastic treatment method of the present invention, at least CFRP and a thermoplastic resin or a material containing a thermoplastic resin are mixed and subjected to a heat treatment, whereby the treated product adheres to the thermoplastic resin. Since they are entangled or covered, scattering can be suppressed when transported by a belt conveyor or the like. As a result, it is possible to suppress carbon fiber scattering and dust generation both during and after the heat treatment.

  In the present invention, “at least carbon fiber reinforced plastic and a thermoplastic resin or a material containing a thermoplastic resin are mixed”, but “mixing” means that each component is simultaneously mixed without stirring or the like. Including adding.

  In the carbon fiber reinforced plastic treatment method of the present invention, the material containing the thermoplastic resin is preferably at least one of shredder dust and waste plastic. It is preferable from the viewpoint of reusing resources by using a waste material such as the above as a material containing a thermoplastic resin. Further, considering the fact that CFRP is pulverized and used as fuel, the above materials are preferable because they generate a large amount of heat.

  Moreover, in the processing method of the carbon fiber reinforced plastic of this invention, it is preferable that the mixing ratio of the said carbon fiber reinforced plastic shall be 5-50 mass%.

  The method for producing a fuel of the present invention includes a step of treating at least a carbon fiber reinforced plastic and a thermoplastic resin or a material containing a thermoplastic resin by the method for treating a carbon fiber reinforced plastic of the present invention, and after the treatment. And crushing the carbon fiber reinforced plastic. The carbon fiber reinforced plastic after the treatment is preferably pulverized to 3 mm or less.

  In the fuel production method of the present invention, the carbon fiber reinforced plastic processed by the carbon fiber reinforced plastic processing method of the present invention described above and having reduced mechanical strength is used, so that it is easily pulverized while suppressing the scattering of processed products. In particular, a fuel having a particle diameter of 0.5 mm or less can be easily produced. That is, the carbon fiber reinforced plastic as a waste material can be effectively used as a fuel.

The block diagram which shows the state which connected two rotary kilns in series. The whole block diagram of the system which uses as a fuel CFRP processed by the processing method of the carbon fiber reinforced plastics of this invention.

  Embodiments of the present invention will be described below.

In the CFRP treatment method of the present embodiment, at least a mixture obtained by mixing CFRP and a thermoplastic resin or a material containing a thermoplastic resin is subjected to heat treatment according to the following conditions 1 and 2.
(Condition 1) The heating temperature of the mixture is set to 250 to 500 ° C.
(Condition 2) The heating time is set within a range of 10 minutes to 12 hours according to the heating temperature.

  The thermoplastic resin or the material containing the thermoplastic resin is a substance that does not generate a filamentous material such as a fiber at the heating temperature of Condition 1, that is, 250 to 500 ° C. The thermoplastic resin is softened in the above temperature range, and includes polyethylene, polypropylene, polystyrene, polycarbonate, polyamide, acrylonitrile / butadiene / styrene, and polyacetal. Among them, polyethylene, polypropylene, polyamide, acrylonitrile / butadiene / Styrene and polycarbonate are preferred.

  The material containing the thermoplastic resin is preferably at least one selected from the group consisting of shredder dust and waste plastic. Examples of the shredder dust include waste automobiles, waste home appliances, and other waste-derived ones. Waste plastic includes construction, container packaging, and agricultural waste.

  Considering that the CFRP after the treatment by the CFRP treatment method of the present invention is pulverized and used as a fuel, the thermoplastic resin or the material containing the thermoplastic resin preferably has a high calorific value.

  As a mixing ratio of the CFRP and the thermoplastic resin or the material containing the thermoplastic resin, it is preferable to mix so that the CFRP is 5 to 50% by mass from the viewpoint of bulk specific gravity and scattering property. The mixing ratio of CFRP is more preferably 10 to 30% by mass.

  By performing heat treatment according to conditions 1 and 2, the mechanical strength of CFRP can be reduced. For example, if the heating temperature is set to 300 ° C., the heating time is set to 1 hour, and similarly to 400 ° C. It is preferable to set the relationship between the heating temperature and the heating time to be inversely proportional, such as 30 minutes if it is set to 500 ° C. and 10 minutes if it is set to 500 ° C. In addition, the preferred relationship between the heating temperature and the heating time varies depending on the size of the CFRP and other conditions, so it is preferable to set appropriately. If the heating temperature is less than 250 ° C, the treatment may take a long time or the grindability may be poor. If the heating temperature exceeds 500 ° C, the recovery rate decreases and the amount of tar and harmful gas generated increases. Detrimental effects such as adhesion of softened resin inside the processing equipment. More preferably, the lower limit of the heating temperature is 300 ° C and the upper limit is 400 ° C.

  The heating means for performing the heat treatment is not particularly limited as long as it can be set in a temperature range of 250 to 500 ° C., and examples thereof include a fixed furnace, a stoker furnace, a rotary kiln furnace, a vertical furnace, and a multistage furnace. Among these, an externally heated rotary kiln furnace with a small amount of exhaust gas treatment is preferable.

  The heat treatment may be any of air, an oxidizing atmosphere, a reducing atmosphere, and an inert atmosphere. However, an oxidizing atmosphere is preferable because the mechanical strength of CFRP can be reduced in a shorter time.

  In the heat treatment, it is preferable to obtain a treatment condition such that the weight reduction rate of CFRP is 10 to 50% in advance, and the heat treatment is preferably performed under the condition, and the weight reduction rate is 10 to 40%. It is more preferable that the content be 15 to 35%. The weight of CFRP is decreased because the resin is low molecular weight and gas is generated with the low molecular weight. The weight reduction rate varies depending on the type and blending amount of the resin. belongs to.

  As described above, the mechanical strength of CFRP is reduced by the CFRP processing method of the present embodiment, so that the pulverization property is improved, and in particular, the fine pulverization becomes easy. However, when the CFRP to be processed exceeds 10 cm, the heating time becomes longer and a load is applied, or the processing amount is reduced, so that it is difficult to adjust the heating time. Therefore, the heat treatment may be performed after roughly pulverizing the CFRP to be treated to 5 cm or less.

  In the CFRP processing method of the present embodiment, CFRP and a thermoplastic resin or a material containing a thermoplastic resin are mixed and subjected to a heat treatment. Therefore, as described above, the treated product adheres to the thermoplastic resin. Or entangled or covered, it is possible to suppress scattering when transported by a belt conveyor or the like. As a result, it is possible to suppress carbon fiber scattering and dust generation both during and after the heat treatment.

  On the other hand, the amount of scattering of the processed product varies depending on the amount of the thermoplastic resin or the material containing the thermoplastic resin to be added, but the amount of addition is determined in advance in consideration of the amount of scattering of the processed product, and the determined addition amount Can be inserted. However, the waste material such as shredder dust has a different thermoplastic resin content for each waste material, and it cannot be easily determined how much the added amount can suppress the scattering. Therefore, it is preferable to monitor the scattering amount of the treated product, or more simply, the dust concentration in the exhaust gas during the heat treatment, and adjust the addition amount of shredder dust and the like based on the monitored dust content. For example, if the monitored concentration of dust content exceeds a predetermined reference value, it may be determined that there is fiber scattering and the amount of shredder dust or the like added is increased.

  FIG. 1 shows a system that executes the CFRP processing method of this embodiment. In FIG. 1, two external heat rotary kiln furnaces 20 and 22 are joined in series, and one end of the external heat rotary kiln furnace 20 is provided with an inlet for a material containing CFRP and a thermoplastic resin or a thermoplastic resin. An input hopper 24 is provided, and an external heat rotary kiln furnace 22 is connected to the other end side via a relay portion 26. In addition, a charging hopper 28 is provided above the relay unit 26.

  The raw material charged from the charging hopper 24 is heated in the external heating rotary kiln furnace 20, then sent to the external heating rotary kiln furnace 22 via the relay unit 26, further heated, and recovered from its end. The external heat rotary kiln furnace 20 includes an exhaust pipe (not shown) having a dust monitoring device, and the concentration of dust in the exhaust gas exhausted from the exhaust pipe can be monitored by the monitoring device.

  When the system shown in FIG. 1 is operated to process CFRP, the charged raw materials are first heated in the external heat rotary kiln furnace 20. At that time, exhaust gas is generated, and the exhaust gas is exhausted from the exhaust pipe. When the concentration of dust content exceeds a preset reference value, a thermoplastic resin or a material containing a thermoplastic resin is charged from the charging hopper 28 above the relay portion 26. That is, in the case where the thermoplastic resin or the material containing the thermoplastic resin in the raw material is insufficient and the fiber of the carbon fiber is generated, the scattering of the fiber can be suppressed by the thermoplastic resin or the material containing the thermoplastic resin.

  In the above embodiment, two external heat rotary kiln furnaces are used, but one can be implemented.

  On the other hand, the fuel manufacturing method of the present embodiment includes a step of processing a carbon fiber reinforced plastic and a thermoplastic resin or a material containing a thermoplastic resin by the carbon fiber reinforced plastic processing method, and a carbon fiber after the processing. Crushing the reinforced plastic. Since the process of processing CFRP and the thermoplastic resin or the material containing the thermoplastic resin has already been described, the process of pulverizing the processed CFRP will be described below.

  In the step of pulverizing the CFRP, the mechanical strength of the CFRP is reduced by the heat treatment in the previous step, so that fine pulverization is easy. Therefore, an apparatus having a strong pulverizing ability is not necessarily required as the pulverizing apparatus. Examples of the pulverizer include a hammer mill, a cutter mill, a shear crusher, a roll crusher, an impact crusher, a rotary mill, a ball mill, a disk mill, and a vertical mill. In addition, when coal and other materials used as fuel in the existing equipment and CFRP are mixed and pulverized at the same time, no new pulverization equipment is required, and pulverization is easy, and the properties of the fuel change greatly. This is preferable.

  As for the particle diameter of CFRP after pulverization, the 3 mm sieve residue is preferably 10% or less, and the 0.5 mm sieve residue is more preferably 10% or less. If the particle size of CFRP exceeds 3 mm, the exhaust gas system is adversely affected. Specifically, when an electric dust collector is used for a dust collector of an exhaust gas system, unburned carbon fibers cause a charging failure of the electric dust collector, the collection performance is lowered, and soot dust is discharged into the atmosphere. When a filtration dust collector is used as the dust collector, unburned carbon fibers are mixed into the collected dust, which hinders the recycling of the collected dust. In the present invention, “the particle size of the Amm sieve residue is 10% or less” means that the weight of the particles remaining on the sieve having an aperture of Amm is 10%.

  Next, a method for producing fuel will be described with reference to the drawings. FIG. 2 shows an example of a system for carrying out the fuel production method of the present invention. This processing system 1 is a tank for storing a received CFRP and a thermoplastic resin or a material containing a thermoplastic resin after heat treatment. 2, a biaxial shear crusher 4 that crushes and crushes CFRP from the tank 2 stepwise, a cutter mill 5 and a vertical mill 6, and a pulverized product P from the vertical mill 6 is charged into the cement firing apparatus 10. It consists of a charging device 7.

  The biaxial shear crusher 4 is a device in which a sharp rotary blade is provided on each of two shafts, and the object to be processed is bitten and crushed. Instead of the biaxial shear crusher 4, a uniaxial shear crusher, a four-axis shear crusher, a roll crusher, an impact crusher, or the like may be used.

  The cutter mill 5 is a device for crushing a processing object so as to be sandwiched by using a shearing force with a cutter attached to a rotor and a fixed blade attached to a casing, and can receive an impact force. It is suitable for crushing things that are difficult to crush finely by absorbing force or extending. Instead of the cutter mill 5, a rotary mill, a hammer mill or the like may be used.

  The vertical mill 6 is a device that has a horizontally rotating table and a plurality of rollers mounted along the upper surface of the table recess, and pulverizes the object to be processed between the table and the rollers. The object to be processed moves in the direction of the outer periphery of the table, and is carried to the separator by an ascending air current and classified. Instead of the vertical mill 6, a ball mill, a disk mill or the like may be used.

  As the charging device 7, a screw type, an ejector type air flow type, a rotary feeder, a screw feeder or the like is used.

  The cement baking apparatus 10 using the pulverized material P obtained by the processing system 1 as a fuel includes a preheater 16 in which cyclones are stacked in multiple stages to preheat the cement raw material CR, and a calcining furnace 15 for calcining the cement raw material CR. The cement kiln (rotary kiln) 11 that includes the main burner 12 and the like and fires the cement raw material CR, and the clinker cooler 13 that cools the cement clinker discharged from the cement kiln 11 and the like.

  Next, a fuel combustion processing method by the processing system 1 having the above configuration will be described.

  After the received heat-treated CFRP and the thermoplastic resin or the material containing the thermoplastic resin are temporarily stored in the tank 2, the biaxial shear crusher 4, the cutter mill 5, and the vertical mill 6 are finally used in this order. Then, the particle size of CFRP is 0.2 mm.

  The pulverized product P from the vertical mill 6 is used as fuel by being fed into the kiln 11a and the kiln bottom 11b of the cement kiln 11 through the feeding device 7 or by being fed into the cement kiln 11 from the main burner 12. Then, the cement raw material CR is fired (the illustrated example shows the case where it is put into the kiln bottom 11b). The cement kiln 11 may be charged from any one of the kiln front 11a, the kiln bottom 11b, and the main burner 12, or may be charged from a plurality of locations. Among these, in order to eliminate unburned carbon fiber, it is preferable to use the main burner 12.

  In the above embodiment, the pulverized material P from the vertical mill 6 is charged into the cement firing device 10 by the charging device 7. However, a tank is provided between the vertical mill 6 and the charging device 7, and the pulverized material P is Once stored in the tank, the cement firing device 10 may be charged by the charging device 7.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

[Examples 1 and 2, Comparative Examples 1 to 5]
1. Raw material used Shredder dust (hereinafter referred to as “CFRP”) and shredder dust (hereinafter referred to as “CFRP”) generated when CFRP is produced and crushed and sorted out of waste home appliances and waste vending machines as materials containing thermoplastic resin , Referred to as “SR”). Table 1 below shows various data of CFRP and SR.

In each of Examples and Comparative Examples, CFRP and SR were mixed at a mixing ratio shown in Table 2 below, and the resulting mixture was put into an external heat rotary kiln furnace and subjected to heat treatment. In each example, the input amount and the set temperature were set to be the values shown in Table 2. Moreover, the temperature of the mixture at the time of a heating was the temperature shown in Table 2. The various conditions of the external heating rotary kiln furnace used for the heating are shown below.
・ External heat kiln diameter φ: 500mm
・ Kiln length L: 3m
・ Inclination angle: 0.75 °
・ Rotation speed: 1.22 rpm
・ Residence time: about 1 hr
[Evaluation]
(1) Amount of falling scattering A sample after the heat treatment was filled in a half capacity (300 to 500 g by weight) of a 1.9 L (radius 10 cm, height 6 cm) container, and then the cap was applied. Next, the container was inverted with the lid on and set at a height of 1 m. The lid was removed horizontally with respect to the ground, and when the sample fell on the ground, the weight scattered outside the frame with a radius of 10 cm directly under the container was measured three times. And the ratio of the scattering weight with respect to filling weight was computed by the percentage. Table 2 shows the calculation results.
(2) Bulk density For samples after heating, in accordance with JIS Z 7302-9: 2002 Waste solidified fuel Part 9: Bulk density test method, the bulk density is measured using a 20L cylindrical container. It was measured. The measurement results are shown in Table 2.
(3) Recovery rate The weight of the sample before heat treatment (processed weight) and the weight of the sample after heat treatment (recovered weight) were measured, and the recovery rate was calculated based on the following formula. Table 2 shows the calculation results.

Recovery rate = Unit calorific value after treatment x Recovered weight / Unit calorific value before treatment x Treated weight Here, the unit calorific value after treatment and the unit calorific value before treatment are regarded as equivalent, and the recovered weight / treatment weight is The recovery rate was used.

  From comparison between Examples 1 and 2 and Comparative Example 1, it can be seen that when SR is added, the bulk density is improved and the amount of scattering is reduced.

  In addition, in the example in which SR was added (Examples 1 to 4, Comparative Example 2) and the example in which SR was not added (Comparative Examples 1 and 3 to 5), the set temperature and the material temperature during heating were compared. It can be seen that the addition of SR increases the heat conduction from the external heat rotary kiln furnace, reduces heat loss, and facilitates temperature control.

  Moreover, it turns out from the comparison of Comparative Examples 3-5 that a recovery rate falls, so that the material temperature at the time of a heating becomes high.

  For reference, 10 g of CFRP having a particle size of 10 to 20 mm is separated from the CFRP obtained in Comparative Examples 1, 3, 4, and 5, and a tabletop small pulverizer (Osaka Chemical Co., Ltd .; Wonder Blender WB-1) is used. After pulverization with a pulverization time of 60 seconds, sieving was performed using a sieve having openings of 1 mm, 0.3 mm, and 0.1 mm. The particle size distribution after pulverization is shown in Table 3.

  In Table 3, only Comparative Examples 1, 3, 4, and 5 of CFRP alone are listed in order to clearly show the effect of temperature on grindability. As shown in Table 3, the higher the temperature, the better the grindability. On the other hand, as can be seen from Table 2, the recovery rate decreases. Therefore, according to the present invention, the grindability can be improved while maintaining the recovery rate, so that it can be suitably used as a fuel.

DESCRIPTION OF SYMBOLS 1 Processing system 2 Tank 4 Biaxial shear crusher 5 Cutter mill 6 Vertical mill 7 Input apparatus 10 Cement baking apparatus 11 Cement kiln 12 Main burner 13 Clinker cooler 15 Pre-heating furnace 16 Preheater 20 22 External heat rotary kiln furnace 24 28 Input hopper 26 Relay part CR Cement raw material P Ground CFRP Carbon fiber reinforced plastic

Claims (5)

Treatment of carbon fiber reinforced plastic, characterized in that at least a carbon fiber reinforced plastic and a mixture obtained by mixing a thermoplastic resin or a material containing a thermoplastic resin are subjected to heat treatment according to the following conditions 1 and 2. Method.
(Condition 1) The heating temperature of the mixture is set to 250 to 500 ° C.
(Condition 2) The heating time is set within a range of 10 minutes to 12 hours according to the heating temperature.   The method for treating carbon fiber reinforced plastic according to claim 1, wherein the material containing the thermoplastic resin is at least one of shredder dust and waste plastic.   The carbon fiber reinforced plastic processing method according to claim 1 or 2, wherein a mixing ratio of the carbon fiber reinforced plastic is 5 to 50% by mass. A step of treating at least a carbon fiber reinforced plastic and a thermoplastic resin or a material containing a thermoplastic resin by the method for treating a carbon fiber reinforced plastic according to any one of claims 1 to 3;
Crushing the carbon fiber reinforced plastic after the treatment;
A fuel production method comprising: The method for producing a fuel according to claim 4, wherein
A method for producing a fuel, wherein the treated carbon fiber reinforced plastic is pulverized to 3 mm or less.