JP2007224082A - Method for recovering inorganic filler and inorganic filler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for recovering an inorganic filler, by which the inorganic filler can be dried and recovered without wet-crushing the inorganic filler in a crushing liquid, while controlling the particle diameter of the inorganic filler. <P>SOLUTION: This method for recovering the inorganic filler is characterized by rotating a disk-like article having a plurality of openings 13 in the side surface in the circumferential direction, supplying a liquid containing the inorganic filler into a groove 12 communicated with the openings 13, gushing out the liquid from the openings 13, contacting the gushed liquid with hot air, and evaporating the liquid to separate and recover the inorganic filler. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inorganic filler recovery method for recovering an inorganic filler from a decomposition product obtained by decomposing a plastic containing an inorganic filler with subcritical water.

  Plastics are lightweight, high-strength, have excellent rust prevention, corrosion resistance, electrical insulation, moldability, colorability, etc., and have the advantage of being capable of mass production. It is widely used for applications. As the amount of plastic used increases, the amount of used plastic discarded also tends to increase. In order to recycle used plastic waste and reduce the burden on the environment, research and development has been actively promoted. Yes.

  Plastics are broadly classified into thermosetting resins and thermoplastic resins. In addition to the use of the resin alone, if strength is required, glass fiber or Fiber reinforced plastics (FRP: Fiber Reinforced Plastics) including reinforcing materials such as carbon fibers are used.

  Thermoplastic resins are relatively easily processed by heating and melting, but thermosetting resins or plastics such as FRP are difficult to process by heating and melting. For this reason, waste plastic is crushed and then landfilled, but in the future, a shortage of landfill is expected. In addition, thermal recycling using waste plastic as fuel has attracted attention. However, when waste plastic is incompletely burned, harmful substances (for example, dioxins) are generated. For this reason, there is an urgent need to establish a method for treating waste plastic.

From such a background, by decomposing plastics such as FRP with a supercritical fluid or subcritical fluid, the resin component of the plastic is decomposed into resin monomers or oligomers, and calcium carbonate, aluminum hydroxide, and glass. A method for recovering and reusing inorganic fibers has been proposed (see Patent Document 1).
JP-A-11-140224

  However, the inorganic substance recovered by the above-described method exists as a residue in which various components are mixed in various proportions, and the surface state is changed by the critical fluid. Therefore, when the inorganic material is reused as the filler, it is necessary to perform drying and pulverization treatment in order to mix the inorganic material with the resin. In particular, it may be necessary to reduce the particle size of the inorganic filler in order to prevent a decrease in strength after reshaping. However, if this operation is simply performed, the decomposition solution after the critical fluid decomposition is filtered. It is necessary to dry the inorganic substance obtained as a residue and to pulverize and classify the inorganic solid substance after drying to obtain an inorganic filler having a desired particle size. For this reason, process conditions must be set for each particle size of the inorganic filler to be adjusted, and the recovery rate of the inorganic filler is reduced.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to dry and recover the inorganic filler while adjusting the particle size of the inorganic substance without wet-grinding the inorganic substance in the decomposition solution. It is to provide a method for recovering a possible inorganic filler.

  In order to solve the above problems, the method for recovering an inorganic filler according to the present invention rotates a disk-shaped object having a plurality of openings on its side surface along the circumferential direction, and is provided on the disk-shaped object. A liquid containing an inorganic filler is supplied to the communicating groove, the liquid is ejected from the opening of the disk-shaped object, the ejected liquid is brought into contact with hot air, and the liquid is evaporated to separate and collect the inorganic filler. To do. In addition, it is desirable that the rotational speed of the disk-shaped object is in the range of 5000 [rpm] to 50000 [rpm]. In addition, it is desirable that the atmospheric temperature in the region where the liquid is ejected and dried is adjusted within a temperature range of 100 [° C.] to 300 [° C.].

  According to the method for recovering an inorganic filler according to the present invention, the inorganic filler can be dried and recovered while adjusting the particle size of the inorganic substance without wet-grinding the inorganic substance in the decomposition solution.

[Critical fluid decomposition process]
In the critical fluid decomposition process, a plastic that has been cut or coarsely pulverized according to the size of the container and a critical fluid are placed in a heat-resistant and pressure-resistant container, and heated and pressurized to make the plastic a monomer or oligomer of resin and inorganic. Decomposes into filler calcium carbonate, aluminum hydroxide and glass fiber. In addition, as a plastic, the plastic using any resin of a thermosetting resin and a thermoplastic resin can also be made into object.

  Specifically, examples of the thermosetting resin include unsaturated polyester resins, acrylic resins, epoxy resins, polyurethane resins, amino resins, and phenol resins. Examples of the thermoplastic resin include vinyl chloride resin, polyethylene resin, polystyrene resin, polypropylene resin, polybutadiene resin, alkyd resin, polycarbonate resin, polyamide resin, and the like.

  As the critical fluid, water, monohydric alcohol, polyhydric alcohol, and the like, or a mixture thereof can be used, but are not limited to these. In addition, when water is used as the critical fluid, it is preferable to use a salt that has been desalted in advance, and an alkali metal hydroxide aqueous solution may be used as the critical fluid in order to promote decomposition. Further, if the mixing amount of the critical fluid is less than 100 parts by weight with respect to 100 parts by weight of the plastic, the plastic cannot be stably decomposed, and conversely if it is 500 parts by weight or more, the waste fluid of the fluid after the decomposition Since processing cost becomes high, it is preferable to make the compounding quantity of the critical fluid with respect to 100 weight part of plastics into the range of 100-500 weight part with respect to 100 weight part of plastic.

  In addition, if the decomposition temperature is less than 180 [° C.], it takes a long time to decompose, and conversely if it exceeds 270 [° C.], the influence of thermal decomposition increases and the resin cannot be recovered as a monomer or oligomer. Since there exists a possibility, it is desirable to make decomposition temperature into the temperature range of 180-270 [degreeC]. Further, the decomposition time and the decomposition pressure are not particularly limited, but it is desirable to set them within the range of 1 to 4 [hours] and 2 to 15 [MPa], respectively, within the above decomposition temperature range. Moreover, when using the aqueous solution of an alkali metal hydroxide as critical water, it is preferable to add the alkali metal hydroxide within a range of 20 to 100 parts by weight with respect to 100 parts by weight of the plastic.

[Step of recovering inorganic filler from decomposition solution]
The inorganic filler is recovered by using a recovery system 1 as shown in FIG. That is, in the collection system 1 shown in FIG. 1, first, heated air (hot air) is supplied from the hot air supply device 5 into the drying chamber 2 to raise the drying chamber 2 to the drying temperature. Next, the decomposition liquid is dropped onto the groove of the disk-type spray dryer dryer 3 rotated at a high speed from the decomposition liquid supply device 4, and the decomposition liquid is provided on the circumferential upper side surface of the disk-type spray dryer dryer 3. The inorganic substance in the decomposition liquid is destroyed by the disc type spray dryer dryer 3 and the decomposition liquid is made into a mist.

  Next, in the recovery device 6, the inorganic filler is sucked from the lower portion of the drying chamber 2, the inorganic filler having a large particle size is separated, and the inorganic filler having a predetermined particle size range is recovered. Recover. By this recovery step, the liquid content in the decomposition liquid is instantly evaporated when brought into contact with hot air, and the inorganic substance can be efficiently dried and recovered as an inorganic filler. The rotational speed of the disk-type spray dryer dryer 3 is preferably in the range of 5000 [rpm] to 50000 [rpm]. In addition, it is desirable that the atmospheric temperature in the region where the decomposition liquid is ejected and dried is adjusted within a temperature range of 100 [° C.] to 300 [° C.].

  Specifically, the disk-type spray dryer dryer 3 has a configuration as shown in FIGS. 2 and 3, and includes a bearing portion 11 to which a rotating shaft is attached, and a groove portion 12 provided on a peripheral portion of the bearing portion 11. And an opening 13 provided along the circumferential direction and communicating with the groove 12. And in the disc type spray dryer dryer 3 which has such a structure, if a decomposition liquid is supplied to the groove part 12 at the time of rotation, a decomposition liquid will be ejected from the opening part 13. FIG.

  There are two types of spray dryer dryers: a disk type using a disk and a nozzle type using a two-fluid nozzle. In the nozzle type spray dryer dryer, the particle size of the inorganic substance in the decomposition liquid exceeds 1 [mm]. If this happens, the decomposition solution is clogged at the nozzle tip during spraying of the decomposition solution, and the inorganic material cannot be dried. In addition, it is difficult to expect the destruction of the inorganic material when using the disk type. The inorganic filler cannot be recovered. Therefore, it is desirable to use a disk type spray dryer dryer as the dryer.

  In addition, when an aqueous solution of an alkali metal hydroxide is used as a critical fluid, since the alkali metal hydroxide is present in the decomposition solution after decomposition, by filtration, the monomer of the resin or After separating into oligomer, calcium carbonate, aluminum hydroxide, and glass fiber, and further washing the alkali metal hydroxide adhering to the inorganic substance with water, the slurry containing the inorganic substance is dried with a disc spray dryer. Also good. And when dripping a decomposition liquid, the inorganic filler which has a desired particle size can be collect | recovered by controlling the rotation speed of the disk shaped thing of a disk type spray dryer, and the atmospheric temperature which spouts a decomposition liquid. .

[Example 1]
In Example 1, first, FRP (FRP bathtub manufactured by Matsushita Electric Works Co., Ltd., calcium carbonate and glass fiber-containing product) 600 [g] coarsely pulverized to a particle size of 2 [mm], concentration 1 [mol / L] 2400 [g] of potassium hydroxide was put into a pressure vessel, the water in the tank was heated to 230 [° C.] with a heater, and the water in the tank was subcritical (critical point (critical temperature 374 [° C.], The critical pressure was 22.1 [MPa]) or less). And after decomposing | disassembling FRP by standing in this state for 2 hours, the decomposition liquid of FRP was obtained by cooling to room temperature. The decomposition solution is a mixture of a resin component monomer or oligomer, calcium carbonate, and glass fiber. Finally, the decomposition solution was dried by dropping the decomposition solution into a disk-type spray dryer dryer to obtain the inorganic filler of Example 1. The disk-type spray dryer dryer has a drying chamber tower diameter of 2 [m], a disk diameter of 65 [cm], a rotational speed of 12000 [rpm], a drying chamber inlet temperature of 200 [° C.], and a drying chamber outlet temperature of 100 [° C. ] Was operated under the conditions of].

[Example 2]
After performing the subcritical decomposition treatment step of Example 1, the decomposition solution was separated into a resin component monomer or oligomer, calcium carbonate, aluminum hydroxide, and glass fiber by a filter press filter. Subsequently, the inorganic cake was washed with a filter press filter, and 3000 [g] of a slurry containing 14 [wt%] of the inorganic substance was recovered in a state where the pH of the filtrate was 10.5. Next, the inorganic filler of Example 2 was obtained by drying the slurry with a disk-type spray dryer dryer under the same conditions as in Example 1.

[Example 3]
The inorganic filler of Example 3 was obtained by drying the decomposition solution of Example 1 under the same conditions as in Example 1 except that the rotational speed of the disk spray dryer was changed to 30000 [rpm].

[Example 4]
After performing the subcritical decomposition treatment step of Example 1, the decomposed FRP decomposition solution 250 [g] and 5 mm ball 400 [g] were placed in a 120 φmm pot mill, and the inorganic substance was rotated for 4 hours at a rotation speed of 200 [rpm]. The operation of performing wet pulverization was repeated. Then, the inorganic filler of Example 4 was obtained by drying a decomposition liquid with the disk type spray dryer drier on the conditions similar to Example 1. FIG.

The results of measuring the average particle diameter of the inorganic fillers of Examples 1 to 4 obtained as described above are shown in Table 1 below. The average particle size was measured using a particle size distribution measuring device (SALD-2000, manufactured by Shimadzu Corporation).

  As shown in Table 1, according to the inorganic fillers of Examples 1 to 4, it can be seen that the inorganic filler with a fine particle diameter can be recovered from the decomposition solution after subcritical decomposition. In particular, according to the inorganic filler of Example 3, the disk-type spray dryer dryer is rotated at a higher speed than Examples 1 and 2, so that the particle size is smaller than that of the inorganic filler of Examples 1 and 2. It turns out that an inorganic filler is obtained. Furthermore, according to the inorganic filler of Example 4, although the inorganic filler was recovered after wet decomposition of the decomposition liquids of Examples 1 to 3 in advance, the inorganic filler having a fine particle diameter can be recovered, Compared with Examples 1 to 3, only inorganic fillers having a large average particle diameter could be recovered. This is because the primary particles are in close contact with each other rather than the effect that the inorganic material is destroyed by the disk-like material when the decomposition liquid in which the particle size of the inorganic material is reduced by spraying in a disk-type spray dryer drier is wet. It is considered that the effect of making particles becomes larger, and the particles are sprayed under hot air in the state of being made into secondary particles and dried instantaneously.

  As mentioned above, although embodiment which applied the invention made by the present inventors was described, this invention is not limited by the description and drawing which make a part of indication of this invention by this embodiment. That is, it should be added that other embodiments, examples, operation techniques, and the like made by those skilled in the art based on the above-described embodiments are all included in the scope of the present invention.

It is a schematic diagram which shows the structure of the collection | recovery system of the inorganic filler used as embodiment of this invention. It is a schematic diagram which shows the structure of the dryer shown in FIG. It is a schematic diagram which shows the other structure of the dryer shown in FIG.

Explanation of symbols

1: Recovery system 2: Drying chamber 3: Disc type spray dryer dryer 4: Decomposition liquid supply device 5: Hot air supply device 6: Recovery device

Claims (4)

A method of recovering an inorganic filler that recovers an inorganic filler from a decomposition product obtained by decomposing a plastic containing an inorganic filler with subcritical water,
A disk-shaped object having a plurality of openings on its side surface is rotated along the circumferential direction, and the liquid containing the inorganic filler is supplied to the groove provided in the disk-shaped object and communicating with the opening, and the liquid is opened. A method for recovering an inorganic filler, characterized in that the inorganic filler is separated and recovered by causing the liquid to be ejected from the container, contacting the ejected liquid with hot air, and evaporating the liquid. It is the collection | recovery method of the inorganic filler of Claim 1, Comprising:
The method for recovering an inorganic filler, wherein a rotational speed of the disk-shaped material is in a range of 5000 [rpm] to 50000 [rpm]. A method for recovering an inorganic filler according to claim 1 or 2,
The method for recovering an inorganic filler, wherein an ambient temperature in a region where the liquid is ejected and evaporated is adjusted to a temperature range of 100 [° C.] to 300 [° C.].   The inorganic filler collect | recovered by the collection | recovery method of the inorganic filler of any one of Claims 1 thru | or 3.

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