Method for separating insoluble raw material and polyamide or polyester, recycled monomer, and polymer

Abstract

A method for continuously separating an insoluble raw material (B) from a composition containing a polyamide or a polyester (A) and the insoluble raw material (B), wherein the following steps (a) and (b) are performed in the stated order　in the provided method for continuously separating an insoluble raw material from a composition containing a polyamide or a polyester and the insoluble raw material: (a) heating the composition to at least the melting temperature of the polyamide or the polyester (A), and (b) continuously separating the insoluble raw material (B) from the composition.

Description

Method for separating insoluble raw materials and polyamide or polyester, recycled monomers, and polymers

[0001] The present invention relates to a method for separating insoluble raw materials and polyamides or polyesters, recycled monomers, and polymers.

[0002] Polyamides and polyesters are materials widely used in textiles, resin products, clothing, and industrial applications. In recent years, growing interest in sustainability, including the SDGs, has led to increased reuse through recycling. While single-material polyamides and polyesters are often cited as targets for recycling, composites containing fillers and other materials are also attracting attention, and the diversification of recycled materials is progressing. To recycle composites efficiently and with a high yield, a widely known method is to separate the fillers and other materials before recycling.

[0003] For example, Patent Document 1 describes a method for separating foreign matter such as thermosetting resin or metal from a thermoplastic resin by melt-filtering using two extruders and a laser filter. This method also describes that the use of a laser filter makes it possible to efficiently and continuously remove even small paint particles. Patent Document 2 describes a method for dissolving a film containing a plastic layer such as polyester or polypropylene and an aluminum layer in an organic solvent, separating the film by gravity, and then melt-filtering the resulting mixture to separate it into three components: polyester, polypropylene, and aluminum.

[0004] JP 2019-6043 A JP 2006-205160 A

[0005] However, the separation conditions in the method of Patent Document 1 are limited to polyolefins such as polyethylene and polypropylene, and therefore cannot be applied to polyamides or polyesters, which have high melting points and undergo hydrolysis and polymerization reactions in an equilibrium reaction with water.

[0006] Furthermore, the method of Patent Document 2 cannot separate polyamide or polyester from a filler such as glass fiber, which has a specific gravity greater than that of water, by specific gravity, and, like Patent Document 1, the separation conditions are limited to polyolefins, and therefore cannot be applied.

[0007] Therefore, an object of the present invention is to provide a method for continuously separating insoluble materials from a composition containing polyamide or polyester and insoluble materials.

[0008] In order to solve the above problems, the present invention has the following features: (1) A method for continuously separating an insoluble raw material (B) from a composition containing a polyamide or polyester (A) and an insoluble raw material (B), the method comprising carrying out the following steps (a) and (b) in this order:

[0009] (a) a step of heating the composition to a temperature equal to or higher than the melting temperature of the polyamide or polyester (A), and (b) a step of continuously separating the insoluble raw material (B) from the composition. (2) The method for separating an insoluble raw material and a polyamide or polyester according to (1) above, wherein the polyamide (A) comprises polyamide 6 or polyamide 66. (3) The method for separating an insoluble raw material and a polyamide or polyester according to (1) or (2) above, wherein the polyester (A) comprises polyethylene terephthalate or polybutylene terephthalate. (4) The method for separating an insoluble raw material and a polyamide or polyester according to any of (1) to (3), wherein the composition is a waste resin molding. (5) The method for separating an insoluble raw material and a polyamide or polyester according to any of (1) to (4), wherein the insoluble raw material (B) comprises a fibrous filler in which 90% or more of the fibrous fillers have a fiber length of 50 to 600 μm, assuming that the total number of fibrous fillers is 100%. (6) The method for separating an insoluble raw material and a polyamide or polyester according to any one of (1) to (5), wherein the heating in step (a) is performed by heating in an extruder. (7) The method for separating an insoluble raw material and a polyamide or polyester according to any one of (1) to (6), wherein the separation in step (b) is performed by filtration. (8) The method for separating an insoluble raw material and a polyamide or polyester according to (7), wherein the separation by filtration uses a rotary perforated plate and / or a woven wire mesh and / or a sintered metal filter as a filter medium. (9) The method for separating an insoluble raw material and a polyamide or polyester according to (8), wherein the insoluble raw material (B) is separated under the condition that Vb≧Va, where Va is the flow rate of the composition through the perforated plate and Vb is the rotational speed of the perforated plate (mm / sec). (10) The method for separating an insoluble raw material and a polyamide or polyester according to any one of (7) to (9), wherein the separation by filtration is performed using a laser filter and a screen changer in this order. (11) The method for separating an insoluble raw material and a polyamide or polyester according to any one of (1) to (10), wherein 0.1 to 12 parts by weight of water is added to 100 parts by weight of the polyamide or polyester (A).(12) A recycled monomer obtained by depolymerizing the polyamide or polyester (A) obtained by the method for separating an insoluble raw material and a polyamide or polyester according to any one of (1) to (11). (13) A recycled polymer obtained by polymerizing the recycled monomer according to (12).

[0010] The present invention can provide a method for separating polyamide or polyester and insoluble materials continuously and in high yield.

[0011] The method for separating an insoluble raw material and a polyamide or polyester of the present invention is a method for continuously separating the insoluble raw material (B) from a composition containing a polyamide or polyester (A) and the insoluble raw material (B), and comprises carrying out the following steps (a) and (b) in this order:

[0012] (a) heating the composition to a temperature equal to or higher than the melting temperature of the polyamide or polyester (A); and (b) continuously separating the insoluble material (B) from the composition.

[0013] The polyamide in the polyamide or polyester (A) can be selected arbitrarily. Examples include aliphatic polyamides such as polyamide 6, polyamide 66, polyamide 12, polyamide 610, polyamide 510, polyamide 410, and polyamide 56, and aromatic polyamides such as polyamide 6T and polyamide 9T. One type of polyamide or two or more types of polyamides may be used. When using a composition consisting of multiple polyamides, the content of the main polyamide is preferably 90% by weight or more out of a total of 100% by weight of the multiple polyamides. This range improves melt stability and filterability, improving the efficiency of separating impurities. The content of the main polyamide is preferably 95% by weight or more, and more preferably 98% by weight or more.

[0014] In the method of the present invention for separating an insoluble raw material and a polyamide or polyester, the polyamide (A) preferably includes polyamide 6 or polyamide 66. Polyamide 6 and polyamide 66 are highly versatile and easily recovered as raw materials, and therefore can be easily used in the composition of the present invention.

[0015] (iii) The polyester in the polyester polyamide or polyester (A) can be selected arbitrarily. Examples include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene naphthalate. One type of polyester or two or more types of polyesters may be used. When a composition consisting of multiple polyesters is used, the content of the main polyester is preferably 90% by weight or more, based on a total of 100% by weight of the multiple polyesters. Furthermore, the content of the main polyester is preferably 95% by weight or more, and more preferably 98% by weight or more.

[0016] In the method for separating an insoluble raw material and a polyamide or polyester according to the present invention, the polyester (A) preferably contains polyethylene terephthalate or polybutylene terephthalate. Polyethylene terephthalate and polybutylene terephthalate are highly versatile and easily recovered as raw materials, making them suitable for use in the composition of the present invention.

[0017] (iii) Insoluble Raw Material In the present invention, the insoluble raw material (B) refers to a raw material that dissolves in an amount of 0.01 g or less in 100 g of water at 20°C. Examples of the insoluble raw material (B) include fibrous fillers such as glass fiber, flat glass fiber, modified cross-section glass fiber, cut glass fiber, flat glass fiber, and carbon fiber, and non-fibrous fillers such as talc, wollastonite, zeolite, and sericite. Two or more of these may be used in combination. The content of the insoluble raw material relative to the polyamide or polyester (A) is preferably 1 to 100 parts by weight per 100 parts by weight of the polyamide or polyester (A).

[0018] In the method for separating an insoluble raw material and a polyamide or polyester of the present invention, it is preferable that the insoluble raw material (B) contains a fibrous filler in which, when the total number of fibrous fillers is taken as 100%, 90% or more of the fibrous fillers have a fiber length of 50 to 600 μm. Here, "90% or more of the fibrous fillers have a fiber length of 50 to 600 μm when the total number of fibrous fillers is taken as 100%" refers to measuring the fiber length of the fibrous filler using the fiber length measurement method described below, and plotting the number of fibers contained in each fiber length interval on the horizontal axis and the number of fibers contained in each fiber length interval on the vertical axis. In addition, the fiber length refers to the fiber length in the composition, not the fiber length before kneading. Fibre fillers are often used as fillers for polyamides and polyesters, and are preferred from the perspective of being able to reuse the separated filler in a wide range of applications. It is preferable that the fiber length of 90% or more of the fibrous filler is 50 μm or more, since the amount of fibrous filler that is difficult to separate is reduced, and the insoluble raw material can be separated efficiently. Also, it is preferable that the fiber length of 90% or more of the fibrous filler is 600 μm or less, since the amount of coarse fibrous filler that affects the separation process is reduced, and the separation can be performed continuously.

[0019] ■ Additives In the present invention, the composition containing the polyamide or polyester (A) and the insoluble raw material (B) may further contain additives within the scope of the present invention. For example, phenolic compounds such as N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamide) and tetrakis[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, sulfur compounds such as phosphorus compounds, mercaptobenzimidazole compounds, dithiocarbamic acid compounds, and organic thioacid compounds, heat stabilizers such as amine compounds such as N,N'-di-2-naphthyl-p-phenylenediamine and 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, isocyanate compounds, organic silicides, and the like. Examples of suitable additives include coupling agents such as ore compounds, organic titanate compounds, organic borane compounds, and epoxy compounds; plasticizers such as polyalkylene oxide oligomer compounds, thioether compounds, ester compounds, and organic phosphorus compounds; nucleating agents such as organic phosphorus compounds and polyether ether ketone; metal soaps such as montanic acid waxes, lithium stearate, and aluminum stearate; release agents such as ethylenediamine-stearic acid-sebacic acid polycondensates and silicone compounds; color inhibitors such as hypophosphites; lubricants, ultraviolet inhibitors, colorants, flame retardants, and foaming agents. When these additives are contained, the content thereof is preferably 10 parts by weight or less, and more preferably 1 part by weight or less, per 100 parts by weight of the polyamide or polyester (A).

[0020] ■ Resin Molded Waste In the present invention, the composition may be resin molded waste. By using the composition as resin molded waste, the amount of waste can be reduced, thereby reducing the environmental impact. Resin molded waste includes industrial waste generated in the manufacturing process of polyamide or polyester products, or post-consumer waste of polyamide or polyester products. Examples of polyamide or polyester products containing insoluble raw materials include molded parts for housing construction materials, molded electrical and electronic parts, aircraft parts, industrial machinery parts, and extrusion molded products. Furthermore, product scraps, pellet scraps, lump scraps, and cutting scraps generated in these production processes are also subject to waste.

[0021] (1) Production Method (2) Heating Method As described above, the method of the present invention for separating the insoluble raw material and the polyamide or polyester comprises the following step (a):

[0022] (a) heating the composition to a temperature equal to or higher than the melting temperature of the polyamide or polyester (A);

[0023] In the step (a), the method for heating the composition containing the polyamide or polyester (A) and the insoluble raw material (B) to a temperature equal to or higher than the melting temperature is not particularly limited and any known method can be used, but it is preferable that the heating in the step (a) is performed using an extruder. By using an extruder, the composition containing the polyamide or polyester (A) and the insoluble raw material (B) can be continuously heated, melted, and extruded, thereby reducing the amount of stagnation and reducing the amount of loss of the polymer to be supplied to the subsequent separation step.

[0024] The heating temperature in the step (a) is preferably 280 to 320° C., for example, when polyamide 6 is melted.

[0025] (ii) Separation Method The method for separating the insoluble raw material and the polyamide or polyester of the present invention involves the following step (b), as described above.

[0026] (b) continuously separating the insoluble material (B) from said composition.

[0027] The method for continuous separation in step (b) is not particularly limited and any known method can be used, but separation in step (b) is preferably separation by filtration. Separation by filtration does not require a complicated process and does not use a solvent, etc., so separation can be performed simply and energy-savingly.

[0028] Separation by filtration is preferably performed using a rotary perforated plate as the filter material. The perforated plate here refers to a plate-like body having a plurality of through-holes. There are no particular limitations on the material of the perforated plate, but metal materials such as stainless steel, carbon steel, Hastelloy, nickel, titanium, chromium, and other alloys are preferred. There are no particular limitations on the shape of the holes drilled in the perforated plate, and shapes such as circular, oval, triangular, and polygonal shapes can be selected. There are also no particular limitations on the size of each hole, but the diameter of the holes is preferably in the range of 10 μm to 500 μm. Such through-holes can be formed by methods such as punching, etching, electroforming, electron beam, laser, drilling, and electrical discharge machining. There are no particular limitations on the ratio of the area of ​​the holes to the total planar area of ​​the perforated plate, i.e., the aperture ratio, but a range of 3 to 40% is preferred, and a range of 5 to 30% is more preferred. By selecting these preferred hole diameters and aperture ratios, the perforated plate can withstand the pressure of the supplied polymer.

[0029] In addition, in the present invention, as described above, a rotary perforated plate is used as the filter material. Here, the rotary type is not particularly limited as long as the perforated plate rotates when the resin composition containing the insoluble raw material (B) passes through the perforated plate as the filter material, and it is preferable that the perforated plate rotates in a direction perpendicular to the resin flow direction. The rotation direction may be a rotation in a fixed direction, or may be an alternating rotation in both directions. The reason why the insoluble raw material can be efficiently separated by using a rotary perforated plate as the filter material is not clear, but for example, the following reason is presumed. The rotation of the perforated plate causes the insoluble raw material to be blocked on the perforated plate, and the insoluble raw material forms a cake layer, thereby exhibiting the effect of suppressing the blockage and clogging of the pores by the insoluble raw material, and it is presumed that the resin composition with a significantly reduced amount of insoluble raw material can be continuously recovered. Furthermore, it is presumed that the rotation of the perforated plate causes the cake layer formed on the perforated plate to peel off, thereby enabling the effect of maintaining a high filtration speed for a long time to be exhibited.

[0030] The rotation speed of the perforated plate used in filter material is not particularly limited, and can be arbitrarily determined according to the type and amount of resin composition, viscosity, and further the type and size of insoluble raw material, the content etc. contained in resin composition.Preferably, when the speed of resin composition flowing to perforated plate is Va (mm / sec), and the rotation speed of perforated plate is Vb (mm / sec), the insoluble raw material is preferably separated under the condition of Vb≧Va.By rotating perforated plate at such a preferred speed, the separation efficiency of insoluble raw material tends to be further improved.It should be noted that the rotation speed Vb of perforated plate here refers to the rotation speed of the outermost periphery of perforated plate, that is, the point farthest from the rotation axis, and can be calculated from the diameter and rotation speed of perforated plate.

[0031] The cake layer made of the insoluble raw materials that has been blocked by such a rotary perforated plate and separated by filtration is preferably continuously discharged outside the system. An example of a discharge mechanism is a method in which a scraper installed on the perforated plate scrapes off the cake layer made of the insoluble raw materials that has rotated together with the perforated plate, and the scraped cake layer is discharged outside the system by a screw.

[0032] In the present invention, the separation by filtration can be preferably exemplified by using perforated plate as filter material and also using woven wire mesh and / or sintered metal.By using perforated plate as filter material and also woven wire mesh and / or sintered metal, it can maintain continuous operation and further improve the separation efficiency of insoluble raw material.Although it may be possible to separate insoluble raw material by using only woven wire mesh and / or sintered metal without using rotary perforated plate, in this case, the frequency of replacing wire mesh increases, and continuous operation decreases.

[0033] Examples of tatami weave wire mesh include plain tatami weave wire mesh, which has vertical and horizontal wires that intersect each other, with the vertical wires being thicker than the horizontal wires and the horizontal wires arranged adjacent to each other, similar to the weave of tatami mats; and twill tatami weave wire mesh, which is woven with thick vertical and horizontal wires, with the horizontal wires arranged adjacent to each other and with two or more vertical and horizontal wires crossing each other. Preferred wire materials for the wire mesh include iron wire, galvanized iron wire, and stainless steel wire (SUS304, SUS316, SUS316L, etc.). The nominal filtration accuracy of the wire mesh is not particularly limited and can be adjusted depending on the size of the foreign matter to be removed. The nominal filtration accuracy of the wire mesh is preferably 5 to 500 μm, more preferably 10 to 300 μm, and even more preferably 20 to 100 μm. Selecting a wire mesh with a low nominal filtration accuracy allows for a high removal rate of the foreign matter to be removed. Furthermore, by selecting a wire mesh with a high nominal filtration accuracy, the pressure loss can be reduced and the fluid flow rate can be maintained high, which is expected to improve the efficiency of the entire separation process.

[0034] Examples of sintered metals include powder sintered compacts obtained by sintering metal powders at high temperatures and fiber sintered compacts obtained by sintering metal fibers. Materials such as iron, galvanized iron, and stainless steel (e.g., SUS304, SUS316, and SUS316L) are preferably used for the sintered metal. The nominal filtration accuracy of the sintered metal is not particularly limited and can be adjusted depending on the size of the foreign matter to be removed. The nominal filtration accuracy of the sintered metal is preferably 1 to 150 μm, and more preferably 10 to 100 μm. By selecting a sintered metal with a low nominal filtration accuracy, it is possible to achieve a high removal rate of the foreign matter to be removed. Furthermore, by selecting a sintered metal with a high nominal filtration accuracy, pressure loss is reduced, allowing the fluid flow rate to be maintained high, which is expected to improve the efficiency of the entire separation process.

[0035] In the method for separating an insoluble raw material and a polyamide or polyester according to the present invention, it is more preferable that the filtration separation uses a laser filter and a screen changer in this order. Here, the laser filter refers to a device that uses a special metal plate with holes drilled by a laser as a filter screen, rather than a typical screen mesh. Furthermore, the screen changer refers to a device that melts plastic scraps and then filters them using a switchable (any mesh size) wire mesh, metal screen, or other screen to remove foreign matter. By adopting such a configuration, most of the insoluble raw material (B) is first continuously filtered and discharged from the system using a laser filter that uses a rotary perforated plate as a filter medium, and then the insoluble raw material (B) with a size of less than 100 μm is filtered using a screen changer containing a woven wire mesh or sintered metal, thereby enabling continuous, highly efficient separation.

[0036] In the method for separating an insoluble raw material and a polyamide or polyester of the present invention, 0.1 to 12 parts by weight of water may be added per 100 parts by weight of polyamide or polyester (A). Adding water promotes hydrolysis of the molten polyamide or polyester, reducing the viscosity of the polymer and thereby improving fluidity and the efficiency of separation of the insoluble impurities (B). The amount of water added is preferably 0.3 to 10 parts by weight, and even more preferably 0.5 to 5.0 parts by weight. Limiting the amount of water added to 12 parts by weight or less prevents excessive hydrolysis, making it easier to recover the polymer after separation. Water can be added either before or after step (a), with adding water after step (a) being more preferred. Adding water to the molten polyamide or polyester reduces the amount of water evaporation and more efficiently reduces the viscosity of the polymer. There are no particular limitations on the water used here; tap water, ion-exchanged water, distilled water, well water, etc. can be used. However, ion-exchanged water or distilled water is preferred to suppress side reactions caused by coexisting salts.

[0037] (ii) Depolymerization The recycled monomer of the present invention can be obtained by depolymerizing the polyamide or polyester (A) obtained by the method of separating an insoluble raw material and a polyamide or polyester of the present invention. The depolymerization method is not particularly limited and any known method can be used, but a superheated steam method or a subcritical water method using a catalyst such as phosphoric acid is preferred. The superheated steam method allows for high-yield recovery of the monomer. Furthermore, the subcritical water method allows for rapid recovery of the monomer without using an organic solvent. Therefore, these depolymerization methods are effective in terms of recovery efficiency and environmental friendliness.

[0038] (ii) Polymerization The recycled polymer of the present invention can be obtained by polymerizing the recycled monomer of the present invention. Since the recycled polymer of the present invention is a highly pure recycled monomer, it can be used as a polymerization raw material for recycled polymers. The polymerization method can be a known method for polyamide or polyester. For example, polyamide 6 can be produced by heat-melting polymerization of ε-caprolactam in the presence of a small amount of water.

[0039] The polymer thus obtained can be melt-kneaded with a fibrous filler or additives as needed to produce a resin composition, and various molded products such as sheets and films can be obtained by known methods such as injection molding or extrusion molding.

[0040] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the descriptions of these examples.

[0041] [Polyamide 6] Polyamide 6 resin ("Amilan" (registered trademark) CM1017 manufactured by Toray Industries, Inc.) with ηr = 2.70 and melting point of 225°C was used. Here, the melt viscosity ηr was measured at 25°C using a 0.01 g / mL solution of 98% concentrated sulfuric acid. The melting point was measured using a differential scanning calorimeter in a nitrogen gas atmosphere by lowering the temperature of the polyamide from a molten state to 30°C at a rate of 20°C / min, and then heating it to the melting point + 40°C at a rate of 20°C / min. However, if two or more endothermic peaks were detected, the temperature of the endothermic peak with the greatest peak intensity was taken as the melting point.

[0042] [Insoluble Raw Material] Glass fibers (T-249 manufactured by Nippon Electric Glass Co., Ltd.) having an average fiber length of 3.0 mm before kneading were used.

[0043] [Polyamide 6 containing glass fiber] Polyamide 6 and glass fiber were blended in a weight ratio of 70 / 30, and a twin-screw extruder (TEX30α manufactured by The Japan Steel Works, Ltd.) was used with a cylinder temperature set at 250°C and a screw rotation speed set at 150 rpm, with polyamide 6 fed from the main feeder and glass fiber fed from the side feeder, and the extruded gut was pelletized to prepare glass fiber-reinforced polyamide 6. When the total number of glass fibers contained in the glass fiber-reinforced polyamide 6 was taken as 100%, the number of fibers having a fiber length of 50 to 600 μm accounted for 95%.

[0044] [Waste of Polyamide 6 Resin Molded Articles] A polyamide 6 resin containing 30% by weight of glass fiber ("Amilan" (registered trademark) CM1011G30 manufactured by Toray Industries, Inc.) was molded and then pulverized to obtain waste of polyamide 6 resin molded articles.

[0045] [Extruder] The pulverized waste polyamide 6 resin moldings was heated and melted using an extruder TEX44αIII equipped with a conical screw manufactured by JSW Corporation.

[0046] [Laser filter] Using CDF300 manufactured by MAS, glass fibers were separated from molten polyamide 6. Glass fibers were collected on the rotating disk filter of the CDF300, scraped off with a scraper installed inside the device, and the glass fibers could be continuously discharged outside the system with a screw.

[0047] [Screen Changer] Using the ECON ESK-630, we separated out microscopic glass fibers less than 100 μm in size that could not be removed using a laser filter. The ESK-630's screen, which is made up of multiple overlapping metal meshes, was able to separate the glass fibers. The machine is also equipped with a backwashing mechanism that washes the screen with the polyamide 6 from which the glass fibers were separated, allowing for automatic cleaning without shutting down the machine when the screen became clogged.

[0048] [Pelletizer] The polyamide 6 from which the glass fibers had been separated was pelletized using an EUP400 manufactured by ECON Corp. The EUP400 is a pelletizer that extrudes the polymer from a nozzle into water and then cuts it with a rotating cutting blade. The cut pellets were transported in water as they were and separated into pellets and water by centrifugation.

[0049] [Amount of Residual Insoluble Materials] 10 g of polyamide 6 resin from which glass fibers had been separated was heated in an electric furnace at 600°C for 3 hours, the amount of ash produced was measured, and the amount of residual insoluble materials and the polymer recovery rate were calculated using the following formulas: Amount of residual insoluble materials (wt%) = [Amount of ash produced (g)] / [Polyamide 6 resin from which glass fibers have been separated (g)] x 100 Polymer recovery rate (wt%) = [Polyamide 6 in polyamide 6 resin from which glass fibers have been separated (g)] / [Polyamide 6 in waste polyamide 6 resin moldings (g)] x 100.

[0050] [Fiber length] 10 g of polyamide 6 resin containing a fibrous filler was heated in an electric furnace at 600 ° C for 3 hours, and water was added dropwise to the resulting ash to prepare a preparation. Subsequently, 10 random locations were observed at 100x magnification using a Leica DVM6 digital microscope. The number of fibers in each fiber length interval was plotted as a histogram divided into intervals from 0 μm to 50 μm in fiber length. The ratio of the number of fibrous fillers falling within the fiber length range of 50 to 600 μm was calculated as a percentage, assuming the total number of observed fibrous fillers to be 100%.

[0051] Example 1: Polyamide 6 resin molding waste, pulverized to a size of 5 to 20 mm and containing 42.8 parts by weight of glass fibers, 95% of which had fiber lengths of 50 to 600 μm, was fed from a feeder to an extruder at a throughput of 60 kg / hr and melted at a temperature of 300°C and a screw rotation speed of 60 rpm. Va, calculated from the residence time of the polyamide 6 resin molding waste in the extruder cylinder and the cylinder length, was 3 mm / sec. Next, molten polyamide resin molding waste containing 30 wt% glass fibers, was fed to a laser filter. A perforated plate with a hole size of 90 μm, a diameter of 300 mm, and an opening ratio of 8%, was installed. At a temperature of 300°C and a scraper rotation speed of 18 rpm, 80 wt% of the glass fibers were separated and discharged outside the system. Vb, calculated from the diameter and rotation speed of the perforated plate, was 204 mm / sec. Furthermore, micro-sized glass fibers with fiber lengths of 50 to 100 μm that could not be separated using the laser filter were separated using a screen changer with a 500-mesh twill weave wire mesh (openings 26 μm), resulting in 95 wt% separation of the total glass fiber mass. The polyamide 6 resin from which the glass fibers had been separated was then cut using a pelletizer to obtain 2 mm granular pellets. The polymer recovery rate was 98.5%.

[0052] A SUS316L autoclave equipped with a stirrer was charged with 20.0 g of polyamide 6 resin from which glass fibers had been separated and 60.0 g of deionized water. The mass ratio of water to polyamide 6 was 3:1. The reaction vessel was purged with nitrogen, sealed under a nitrogen pressure of 0.5 MPa, and then the reaction was carried out by holding the temperature at 340°C for 15 minutes while stirring at 200 rpm. The pressure reached during the reaction was 13.2 MPa. After completion of the reaction, the vessel was cooled to room temperature and the depolymerized recycled lactam was recovered.

[0053] Water was added to the recycled lactam to prepare a 90 wt. % caprolactam aqueous solution, which was then placed in a polymerization vessel. The raw materials were heated while being stirred in a sealed state. When the internal pressure reached 1 MPa, water vapor was distilled off and the pressure was maintained at that level. When the internal liquid temperature reached 250°C, the internal pressure was gradually reduced to atmospheric pressure over 70 minutes. The internal liquid temperature at this time was 260°C. Subsequently, nitrogen was flowed into the gas phase of the vessel for 60 minutes while maintaining the internal liquid temperature at 260°C, completing the polymerization. After polymerization was completed, molten nylon 6 was extruded from the bottom of the polymerization vessel into a gut shape, cooled with water, and cut into pellets using a pelletizer. Low molecular weight impurities were extracted from the pellets using hot water, yielding chemically recycled polyamide 6 resin pellets.

[0054] Example 2: Polyamide 6 resin molding waste, pulverized to a size of 5-20 mm, containing 42.8 parts by weight of glass fiber, 95% of which had fiber lengths of 50-600 μm, was fed from a feeder to an extruder at a throughput of 60 kg / hr and melted at 300°C and a screw rotation speed of 60 rpm. Next, molten polyamide resin molding waste containing 30% by weight of glass fiber was fed to a screen changer, where 75% by weight of the total glass fiber was separated at 300°C and a filter diameter of 300 μm. The polyamide 6 resin from which the glass fibers had been separated was then cut using a pelletizer to obtain 2 mm granular pellets. The polymer recovery rate was 92.5%.

[0055] Thereafter, the obtained pellets were depolymerized and polymerized under the conditions described in Example 1 to obtain a recycled polymer.

[0056] Example 3: (1) Polyamide 6 resin molding waste containing 42.8 parts by weight of glass fibers, 95% of which had fiber lengths of 50 to 600 μm, was fed from a feeder to an extruder at a throughput of 60 kg / hr and melted at a temperature of 300°C and a screw rotation speed of 60 rpm. Furthermore, 5 parts by weight of water at 25°C per 100 parts by weight of polyamide 6 resin was added to the cylinder from an addition device installed 1.3 m forward of the extruder's raw material inlet and mixed with the molten polyamide. Va, calculated from the residence time of the polyamide 6 resin molding waste in the extruder cylinder and the cylinder length, was 3 mm / sec. Next, molten polyamide resin molding waste containing 30% by weight of glass fiber was fed to a laser filter, and a perforated plate with a hole size of 90 μm, a diameter of 300 mm, and an opening ratio of 8% was installed. At a temperature of 300°C and a scraper rotation speed of 18 rpm, 80% by weight of the glass fiber was separated from the total amount of glass fiber and discharged outside the system. Vb calculated from the diameter and rotation speed of the perforated plate was 204 mm / sec. Furthermore, micro-sized glass fibers with fiber lengths of 50 to 100 μm that could not be separated by the laser filter were separated using a screen changer using a 500-mesh twill wire mesh (opening 26 μm), resulting in 97.5% by weight of the total amount of glass fiber. The polyamide 6 resin from which the glass fiber had been separated was then cut using a pelletizer to obtain 2 mm granular pellets. The polymer recovery rate was 99.25%.

[0057] Thereafter, the obtained pellets were depolymerized and polymerized under the conditions described in Example 1 to obtain a recycled polymer.

[0058] (Example 4) Insoluble raw materials were separated under the same conditions as in Example 3, except that 0.1 parts by weight of water at 25°C per 100 parts by weight of polyamide 6 resin was added to the inside of the cylinder from an addition device installed 1.3 m ahead of the raw material inlet of the extruder. Note that 96.5% of the glass fibers were separated based on the total amount of glass fibers, and the polymer recovery rate was 98.95%.

[0059] (Example 5) Insoluble raw materials were separated under the same conditions as in Example 3, except that 10 parts by weight of water at 25°C per 100 parts by weight of polyamide 6 resin was added to the inside of the cylinder from an addition device installed 1.3 m ahead of the raw material inlet of the extruder. Note that 98.5% of the glass fibers were separated based on the total amount of glass fibers, and the polymer recovery rate was 99.55%.

[0060] (Example 6) Insoluble raw materials were separated under the same conditions as in Example 3, except that 15 parts by weight of water at 25°C per 100 parts by weight of polyamide 6 resin was added to the cylinder from an addition device installed 1.3 m ahead of the raw material inlet of the extruder. 98.5% of the glass fibers were separated based on the total amount of glass fibers, and the polymer recovery rate was 62.5%. The reason why the polymer recovery rate was lower than in other examples is presumably because the amount of water added was greater than in other examples, which led to more progress in polymer hydrolysis.

[0061] Example 7 Insoluble raw materials were separated under the same conditions as in Example 1, except that waste polyamide 66 resin moldings pulverized to a size of 5 to 20 mm containing 42.8 parts by weight of glass fibers, 95% of which had fiber lengths of 50 to 600 μm, when the total number of glass fibers was taken as 100%, were used. Note that 93% of the glass fibers were separated based on the total amount of glass fibers, and the polymer recovery rate was 95%.

[0062] Example 8 Insoluble raw materials were separated under the same conditions as in Example 1, except that waste polyethylene terephthalate resin moldings pulverized to sizes of 5 to 20 mm containing 42.8 parts by weight of glass fibers, 95% of which had fiber lengths of 50 to 600 μm, when the total number of glass fibers was taken as 100%, were used. Note that 95% of the glass fibers were separated based on the total amount of glass fibers, and the polymer recovery rate was 98.5%.

[0063] Example 9 Insoluble raw materials were separated under the same conditions as in Example 1, except that waste polybutylene terephthalate resin moldings pulverized to a size of 5 to 20 mm containing 42.8 parts by weight of glass fibers, 95% of which had fiber lengths of 50 to 600 μm, when the total number of glass fibers was taken as 100%, were used. Note that 93% of the glass fibers were separated based on the total amount of glass fibers, and the polymer recovery rate was 95.0%.

[0064] (Example 10) Except for using an intake manifold as the resin molding waste, insoluble raw materials were separated under the same conditions as in Example 1. Note that 97% of the total amount of glass fibers was separated, and the polymer recovery rate was 98.5%.

[0065] (Example 11) Insoluble raw materials were separated under the same conditions as in Example 1, except that the flow rate Va of the resin composition relative to the perforated plate was set to 3 mm / sec and the rotation rate Vb of the perforated plate was set to 306 mm / sec. Note that 93% of the total amount of glass fibers was separated, and the polymer recovery rate was 97%.

[0066] (Example 12) Insoluble raw materials were separated under the same conditions as in Example 1, except that the flow rate Va of the resin composition relative to the perforated plate was set to 4.5 mm / sec and the rotation rate Vb of the perforated plate was set to 204 mm / sec. Note that 97% of the glass fibers were separated based on the total amount of glass fibers, and the polymer recovery rate was 98.5%.

Claims

1. A method for continuously separating an insoluble material (B) from a composition containing a polyamide or polyester (A) and an insoluble material (B), the method comprising carrying out the following steps (a) and (b) in this order: (a) heating the composition to a temperature equal to or higher than the melting temperature of the polyamide or polyester (A); and (b) continuously separating the insoluble material (B) from the composition.

2. The method for separating an insoluble material and a polyamide or polyester according to claim 1, wherein the polyamide (A) comprises polyamide 6 or polyamide 66.

3. The method for separating an insoluble material and a polyamide or polyester according to claim 1, wherein the polyester (A) comprises polyethylene terephthalate or polybutylene terephthalate.

4. The method for separating an insoluble raw material and a polyamide or polyester according to claim 1, wherein the composition is a waste resin molding.

5. The method for separating an insoluble raw material and a polyamide or polyester according to claim 1, wherein the insoluble raw material (B) contains a fibrous filler in which the number of fibrous fillers having a fiber length of 50 to 600 μm accounts for 90% or more of the total number of fibrous fillers taken as 100%.

6. The method for separating an insoluble raw material and a polyamide or polyester according to claim 1, wherein the heating in step (a) is performed in an extruder.

7. The method for separating an insoluble material and a polyamide or polyester according to claim 1, wherein the separation in step (b) is performed by filtration.

8. The method for separating an insoluble material and a polyamide or polyester according to claim 7, wherein the separation by filtration is carried out using a rotary perforated plate and / or a woven wire mesh and / or a sintered metal as a filter medium.

9. A method for separating an insoluble raw material and a polyamide or polyester according to claim 8, wherein the insoluble raw material (B) is separated under the condition that Vb≧Va, where Va is the flow speed of the composition relative to the perforated plate and Vb is the rotation speed of the perforated plate (mm / sec).

10. The method for separating an insoluble material and a polyamide or polyester according to claim 7, wherein the separation by filtration is performed using a laser filter and a screen changer in this order.

11. The method for separating an insoluble material and a polyamide or polyester according to claim 1, wherein 0.1 to 12 parts by weight of water is added per 100 parts by weight of the polyamide or polyester (A).

12. A recycled monomer obtained by depolymerizing polyamide or polyester (A) obtained by the method for separating an insoluble raw material and polyamide or polyester according to any one of claims 1 to 11.

13. A recycled polymer obtained by polymerizing the recycled monomer according to claim 12.