Decoloring method and decoloring apparatus

Abstract

[Problem] To make it possible to appropriately decolorize a decoloration target object without imposing a burden on a user. [Solution] This decoloring method is for decoloring a dye of a staining material from a decoloration target object including fibers that have been colored or stained by the staining material. The dye is held in gaps of molecular chains of the fibers. The method comprises a decoloring step for washing the decoloration target object by using a first decoloring liquid at a decoloring temperature that is equal to or higher than a fiber-opening temperature at which the molecular chains are loosened to such a degree that the dye escapes from the gaps of the molecular chains of the fibers included in the decoloration target object.

Description

Bleaching method and bleaching device

[0001] The present invention relates to a bleaching method and a bleaching device.

[0002] Currently, a technique for printing on fabric using transfer printing is known. Transfer printing is a printing method in which an image is drawn on a transfer sheet with transfer ink and then transferred to fabric. Furthermore, a technique for bleaching fabric to remove the image from the fabric on which the image was drawn is known for fabric recycling.

[0003] For example, Patent Document 1 describes a technique for discharging dyed fabric by printing a discharging agent onto the fabric using an inkjet method, and also describes an inkjet printing device that ejects discharging ink for such discharging.

[0004] Japanese Patent Application Laid-Open No. 2007-224128

[0005] Generally, bleaching an object requires applying a solvent to the object, heat pressing the object and an absorbent material that absorbs the solvent, supplying the absorbent material to the object, and transporting the object. Therefore, bleaching objects with three-dimensional shapes, such as stuffed toys, has been difficult. Furthermore, a large absorbent material is required in proportion to the area of ​​the area to be bleached. As the object to be bleached becomes larger, a large amount of absorbent material becomes waste, which is uneconomical and places a heavy burden on the environment.

[0006] Furthermore, it is desirable that the series of steps required for bleaching an object to be bleached be performed automatically with as little burden (particularly labor or health burden) as possible on the user. The inkjet printing device described in Patent Document 1 is not a device that can automatically perform the series of steps required for bleaching, and may be a burden for the user.

[0007] Therefore, there is a demand for a method that allows the object to be bleached appropriately without imposing a burden on the user.

[0008] A bleaching method according to a first aspect of the present invention for bleaching a pigment of a dye from an object to be bleached, which includes fibers dyed or colored with the dye, includes: a bleaching step of washing the object to be bleached with a first bleaching solution having a bleaching temperature equal to or higher than a fiber-opening temperature at which the molecular chains of the fibers contained in the object to be bleached are relaxed to an extent that the pigment escapes from the gaps between the molecular chains of the fibers, the pigment being held in the gaps between the molecular chains of the fibers.

[0009] The dye may be a disperse dye, and the fiber may be a fiber that can be dyed or colored with the disperse dye.

[0010] In the bleaching step, the fibers may be brought into contact with the first bleaching solution at the bleaching temperature in a treatment tank.

[0011] In the bleaching step, the object to be bleached may be carried into the first bleaching solution in the treatment tank, which contains the first bleaching solution heated to the bleaching temperature.

[0012] In the bleaching step, the first bleaching solution may be heated to the bleaching temperature in the treatment tank containing the object to be bleached and the first bleaching solution at a temperature lower than the bleaching temperature.

[0013] The bleaching step may include a stimulus application step of applying a mechanical stimulus to the object to be bleached after or during contact of the first bleaching solution with the fiber.

[0014] The stimulus application step may include any one of a step of stirring, a step of shaking, and a step of ultrasonically treating the first bleaching solution containing the object to be bleached in the treatment tank.

[0015] The decolorizing step may be carried out while supplying new or recycled first decolorizing solution to the treatment tank and discharging excess first decolorizing solution from the treatment tank.

[0016] The bleaching step may include a step of spraying the first bleaching solution as a liquid or gas onto the object to be bleached at the bleaching temperature.

[0017] After the bleaching step, the method may further include a rinsing step of contacting the object to be bleached with a second bleaching solution that bleaches the pigment.

[0018] The second bleaching liquid may be the same type of liquid as the first bleaching liquid.

[0019] The method may further include a dewatering step of removing the first bleaching solution from the object to be bleached, and a drying step of drying the object to be bleached.

[0020] The fibers may include at least one of polyester fibers and nylon fibers.

[0021] The bleaching temperature may be lower than the boiling point of the first bleaching solution.

[0022] A bleaching device according to a second aspect of the present invention, which bleaches the pigment of a dye from a bleaching object containing fibers dyed or colored with the dye, includes: a bleaching section that washes the bleaching object with a first bleaching solution that bleaches the dye and has a bleaching temperature equal to or higher than a fiber-opening temperature at which molecular chains of the fibers contained in the bleaching object loosen to an extent that the pigment escapes through gaps in the molecular chains; an exhaust device that exhausts fumes of the first bleaching solution generated from the bleaching section; a fume recovery device that returns the fumes to a liquid and recovers them; and a transport section that transports the bleaching object to the bleaching section and transports the bleached object out of the bleaching section.

[0023] The bleaching device may further include a sealed housing that houses the bleaching unit and the conveying unit, and the exhaust device may be attached to the sealed housing so as to exhaust the fumes from inside the sealed housing to the outside.

[0024] The bleaching device may further include a hood disposed above an opening from which the fumes exit the bleaching section and covering the opening, and the exhaust device may be attached to the hood.

[0025] The bleaching unit may include a first treatment tank for containing the first bleaching liquid, a first storage tank for storing the first bleaching liquid and supplying the first bleaching liquid to the first treatment tank, and a heating device for heating the first bleaching liquid in the first treatment tank or the first storage tank to the bleaching temperature.

[0026] The bleaching unit may include a stimulating device that applies a mechanical stimulus to the bleaching target object.

[0027] The stimulation device may include at least one of a stirring device that stirs the object to be bleached and the first bleaching solution in the first treatment tank, a shaking device that shakes the first bleaching solution in the first treatment tank together with the object to be bleached, an ultrasonic treatment device that ultrasonically treats the first bleaching solution together with the object to be bleached in the first treatment tank, and a stirring blade that is arranged to come into contact with the object to be bleached in the first treatment tank.

[0028] The decolorizing unit may supply the first decolorizing liquid from the first storage tank to the first treatment tank, and wash the object to be decolorized with the first decolorizing liquid while draining excess first decolorizing liquid from the first treatment tank.

[0029] The bleaching unit may include a spray device that sprays the first bleaching solution at the bleaching temperature onto the object to be bleached as a liquid or gas.

[0030] The bleaching unit may further wash the object to be bleached that has been bleached with the first bleaching solution with a second bleaching solution that has a temperature lower than the fiber-opening temperature and that bleaches the dye.

[0031] The bleaching device may further include a rinsing section that washes the object to be bleached that has been bleached in the bleaching section with a second bleaching solution that has a temperature lower than the fiber-opening temperature and bleaches the dye, and the conveying section may convey the object to be bleached after bleaching from the bleaching section to the rinsing section.

[0032] The decolorizing device may further include an impurity removal device that removes the dye from the used first decolorizing solution discharged from the decolorizing section.

[0033] The bleaching device may further include a dewatering device that removes liquid from the object to be bleached, and a drying device that dries the object to be bleached.

[0034] The decolorizing device may be constructed to be explosion-proof.

[0035] The fibers may include at least one of polyester fibers and nylon fibers.

[0036] According to the present invention, an object to be bleached can be appropriately bleached without imposing a burden on the user.

[0037] 1 is a flow chart of a bleaching method according to a first embodiment of the present invention; 2 is a configuration diagram of a bleaching device according to a second embodiment of the present invention; 3 is a schematic diagram of a bleaching device according to a second embodiment of the present invention (viewed from the side); 4 is a schematic diagram of a bleaching unit of a bleaching device according to a second embodiment of the present invention (viewed from the side); 5 is a schematic diagram of a rinsing unit of a bleaching device according to a second embodiment of the present invention (viewed from the side); 6 is a schematic diagram of a bleaching unit of a bleaching device according to a modified example of the present invention (viewed from the side);

[0038] (First embodiment) A bleaching method according to a first embodiment of the present invention will be described. This bleaching method is a method for bleaching disperse dyes that have been used to dye or color an object to be bleached using a bleaching solution. As shown in Figure 1, this bleaching method mainly involves a bleaching step S1, a rinsing step S2, a dewatering step S3, and a drying step S4.

[0039] (Object to be bleached) The object to be bleached is any article containing polyester or nylon fibers. The object to be bleached includes polyester or nylon fibers dyed or colored with a disperse dye. For example, the object to be bleached may include a knit or fabric formed from polyester yarn, nylon yarn, polyester blended yarn, or nylon blended yarn. Fibers blended with polyester or nylon include cotton, polyurethane, rayon, linen, etc., and also include blends of polyester and nylon. The blend ratio of polyester or nylon to other blended yarns (polyester or nylon: other blended yarns) can be set to any ratio ranging from 50:50 to 90:10. The shape of the object to be bleached is arbitrary, and examples of the object to be bleached include flags, clothing, and bolts of fabric. It may also be an object with a three-dimensional shape, such as a stuffed toy.

[0040] (Disperse dye) Any disperse dye may be used as long as the pigment contained in the disperse dye is captured in gaps between the molecular chains of the polyester or nylon fibers in the object to be bleached, thereby dyeing or coloring the fibers in the object to be bleached. Methods for dyeing the polyester or nylon fibers in the object to be bleached with a disperse dye include sublimation transfer printing, direct sublimation printing, exhaust dyeing, and thermosol dyeing.

[0041] (Bleaching Liquid) The bleaching liquid used in the bleaching step S1 and rinsing step S2 described below can be selected arbitrarily as long as it satisfies the following conditions: (i) It has a boiling point that exceeds the temperature at which the bleaching step S1 and rinsing step S2 are performed. (ii) It is capable of dissolving disperse dyes. (iii) It does not have a significant adverse effect on the object to be bleached. Here, the boiling point of (i) above is preferably a boiling point that exceeds the temperature at which bleaching is performed in the bleaching step S1 (bleaching temperature). Furthermore, examples of the "adverse effect" of (iii) above include a change in the color of the fibers themselves that make up the object to be bleached, deterioration in the texture of the fibers, shrinkage of the fibers, etc.

[0042] The main component of the decolorizing solution may be, for example, an organic solvent. Examples of organic solvents include dimethyl succinate (boiling point: 200°C), dimethyl glutarate (boiling point: 214°C), dimethyl adipate (boiling point: 245°C), dihexyl ethyl acetate (boiling point: 218°C), 3-methoxy-N,N-dimethylpropanamide (boiling point: 215°C), benzyl benzoate (boiling point: 325°C), diethylene glycol (boiling point: 245°C), trichloroethane (boiling point: 74°C), dimethyl sulfoxide (boiling point: 189°C), acetone (boiling point: 56°C), methyl ethyl ketone (boiling point: 80°C), and propylene glycol monomethyl ether acetate (boiling point: 146°C). When using the organic solvents exemplified here, they may be diluted with water or other organic solvents, as appropriate.

[0043] (Bleaching Step S1) In the bleaching step S1, the object to be bleached is washed with a bleaching solution in a first treatment tank, which contains a bleaching solution heated to a predetermined bleaching temperature.

[0044] In polyester or nylon fibers dyed with disperse dyes, the pigments of the disperse dyes are held in the gaps between the molecular chains of the fibers. At room temperature, the pigments of the disperse dyes present in the gaps between the molecular chains have high wash fastness, and the pigments of the disperse dyes do not easily escape from the gaps between the molecular chains. In other words, polyester or nylon fibers dyed with disperse dyes are not easily decolorized. However, when polyester or nylon fibers are heated at high temperatures, the gaps between the molecular chains widen, making it easier for the pigments of the disperse dyes to escape from the gaps between the molecular chains (fibers). In other words, polyester or nylon fibers dyed with disperse dyes are easily decolorized.

[0045] Therefore, in the bleaching step S1, a bleaching temperature equal to or higher than the fiber-spreading temperature is used. Here, the fiber-spreading temperature refers to the temperature at which the gaps between the molecular chains of the polyester or nylon fibers contained in the material to be bleached widen (loosen) enough to allow the pigment of the disperse dye to escape through the gaps between the molecular chains. For example, the bleaching temperature may be equal to or higher than the glass transition point of the polyester or nylon fibers contained in the material to be bleached. Furthermore, the bleaching temperature may be equal to or higher than the dyeing temperature of the polyester or nylon fibers contained in the material to be bleached in an exhaust dyeing method, for example, the dyeing temperature. In particular, when the material to be bleached contains polyester fibers, the bleaching temperature may be equal to or higher than 110°C, 115°C, 120°C, 125°C, or 130°C. Furthermore, when the material to be bleached contains nylon fibers, the bleaching temperature may be equal to or higher than 70°C, 80°C, 90°C, or 100°C. Regardless of the bleaching temperature, the upper limit of the bleaching temperature is the boiling point of the bleaching solution. The upper limit of the bleaching temperature varies depending on the fibers that make up the object to be bleached. Here, the "boiling point" is not limited to the boiling point at normal pressure, but also includes the boiling point under a pressurized environment.

[0046] In the bleaching step S1, the object to be bleached is washed with a bleaching solution to bleach it, and the main steps are a heating step in which the object to be bleached is heated through the bleaching solution, and a stirring step in which the object to be bleached and the bleaching solution are stirred.

[0047] In the heating step, the object to be bleached is heated via the bleaching solution in a first treatment tank containing the bleaching solution at the bleaching temperature. For example, the object to be bleached is brought into contact with the bleaching solution at the bleaching temperature in the first treatment tank. Specifically, the fibers contained in the object to be bleached are brought into contact with the bleaching solution at the bleaching temperature. This brings the temperature of the object to be bleached closer to the bleaching temperature, widening the gaps between the molecular chains of the polyester or nylon fibers contained in the object to be bleached. This is expected to allow the pigment of the disperse dye held in the gaps between the molecular chains to escape from the gaps in the molecular chains, making the object to be bleached easier to bleach.

[0048] The heating step may be performed by simultaneously or sequentially introducing the object to be bleached and the bleaching solution heated to the bleaching temperature into the first treatment tank. For example, the bleaching solution heated to the bleaching temperature may be prepared in advance in the first treatment tank, and the object to be bleached may be carried into the second treatment tank in which the bleaching solution has been prepared. Alternatively, the heating step may be performed by simultaneously or sequentially introducing the object to be bleached and the bleaching solution into the first treatment tank, and then heating the bleaching solution in the first treatment tank containing the object to be bleached and the bleaching solution to the bleaching temperature. In either case of using the bleaching solution heated to the bleaching temperature or heating the bleaching solution in the first treatment tank, the order in which the object to be bleached and the bleaching solution are introduced into the first treatment tank does not matter.

[0049] In the stirring step, the material to be bleached and the bleaching solution are stirred in the first treatment tank. The stirring step may be performed after the heating step or in parallel with the heating step. When the stirring step is performed in parallel with the heating step, the following may be performed: (i) the material to be bleached is immersed (contacted) in the bleaching solution in the first treatment tank for a predetermined time, and the bleaching solution is allowed to penetrate the fibers, and then the stirring step is performed; or (ii) the bleaching step is performed without ensuring a immersion time, and the material to be bleached is stirred in the bleaching solution while the bleaching solution is allowed to penetrate the fibers. This is expected to promote the release of the pigment of the disperse dye from the gaps in the molecular chains of the fiber that have been loosened by heating.

[0050] (Rinsing step S2) In the rinsing step S2, the material to be bleached is washed with the bleaching solution in a second treatment tank containing the bleaching solution at a temperature lower than the fiber-spreading temperature. The rinsing step S2 mainly includes a cooling step in which the material to be bleached is cooled using the bleaching solution, and an agitation step in which the material to be bleached and the bleaching solution are agitated.

[0051] In the cooling step, the object to be bleached after the bleaching step S1 is cooled in a second treatment tank. A bleaching solution at a temperature below the fiber-spreading temperature, for example, room temperature or normal temperature (for example, about 20°C or 25°C), is stored in the second treatment tank. In the second treatment tank, the object to be bleached is cooled by contact with the bleaching solution. In other words, the object to be bleached is cooled via the bleaching solution. For example, in the first treatment tank, the object to be bleached is brought into contact with a bleaching solution at a temperature below the fiber-spreading temperature. Specifically, the fibers contained in the object to be bleached are brought into contact with a bleaching solution at a temperature below the fiber-spreading temperature. When the temperature of the object to be bleached drops below the fiber-spreading temperature due to contact with the bleaching solution, the molecular chain structure of the polyester or nylon fibers contained in the object to be bleached is restored. As a result, the gaps between the expanded molecular chains return to their original narrower state, and it is expected that the pigment of the disperse dye remaining on the surface of the object to be bleached will be prevented from being reabsorbed into the gaps between the molecular chains of the fibers.

[0052] The cooling step may be performed by simultaneously or sequentially introducing the material to be bleached and a bleaching solution having a temperature below the fiber-spreading temperature into the second treatment tank. For example, a bleaching solution having a temperature below the fiber-spreading temperature may be prepared in advance in the second treatment tank, and the material to be bleached may be carried into the second treatment tank containing the bleaching solution. Furthermore, the cooling step may be performed by introducing the material to be bleached into the second treatment tank, and then introducing a bleaching solution having a temperature below the fiber-spreading temperature into the second treatment tank.

[0053] In the stirring step, the object to be bleached and the bleaching solution are stirred in the second treatment tank. The stirring step may be performed after the cooling step or may be performed in parallel with the cooling step. This allows the pigment of the disperse dye remaining on the surface of the object to be bleached to dissolve in the bleaching solution and be more reliably removed from the surface of the object to be bleached.

[0054] In the dewatering step S3, the object to be decolorized after the rinsing step S2 is removed from the second treatment tank, and the decolorizing solution is removed from the object to be decolorized. The dewatering can be performed using, for example, a centrifugal or compression type dewatering device (dehydrator).

[0055] (Drying Step S4) In the drying step S4, the dehydrated bleached object is dried. Examples of drying methods include natural drying, press drying, and air drying. In natural drying, the bleached object is dried by leaving it at room temperature or normal temperature (25°C). In press drying, the bleached object is dried by coaxially applying heat and pressure using a press device. In air drying, the bleached object is dried by blowing warm air or the like onto the bleached object.

[0056] (Effects of the First Embodiment) Conventionally, fiber fabrics have been bleached by applying a bleaching solution to the fiber fabric to be bleached, pressing an absorbent against the fabric, and then applying a heat press to transfer the dye from the fiber fabric to the absorbent. This method has been difficult to use to bleach objects with three-dimensional shapes, such as stuffed toys. Furthermore, a large absorbent is required in proportion to the area of ​​the area to be bleached. As a result, a large amount of absorbent becomes waste as the object to be bleached becomes larger, which is uneconomical and has a high environmental impact. Due to these uneconomical and environmental impacts, there have been substantial limitations on the size of the object to be bleached.

[0057] On the other hand, according to the bleaching method of this embodiment, disperse dyes can be decolorized from an object to be bleached by washing the object with a bleaching solution heated to a predetermined bleaching temperature. Therefore, this bleaching method is not limited to objects with flat shapes, and can also decolorize three-dimensional products. Furthermore, since this bleaching method does not require an absorbent, there are no economic or environmental issues associated with enlarging the object to be bleached, and there are no conventional limitations on the size of the object to be bleached. Therefore, this bleaching method can decolorize an object effectively regardless of its shape or size.

[0058] (Variation 1-1) The bleaching step S1 can be realized by any method as long as the object to be bleached is washed using a bleaching solution that can dissolve the pigment of the disperse dye at a bleaching temperature equal to or higher than the glass transition point of the polyester or nylon fibers contained in the object to be bleached.

[0059] (Variation 1-1-1) In the first embodiment, a stirring step is performed in the bleaching step S1 to stir the bleaching object and the bleaching solution, thereby applying a mechanical stimulus to the bleaching object. The mechanical stimulus may be applied to the bleaching object by a method other than stirring, as long as it can decolorize the disperse dye from the bleaching object. For example, a stimulus application step may be performed instead of the stirring step.

[0060] Methods of applying a mechanical stimulus to the object to be bleached in the stimulus application step include, for example, shaking the bleaching solution together with the object to be bleached in the first treatment tank, ultrasonically treating the bleaching solution together with the object to be bleached in the first treatment tank, and stimulating the object to be bleached by contacting a rotating blade with the object to be bleached in the first treatment tank.

[0061] (Variation 1-1-2) In the first embodiment and the above-described variations, the bleaching step S1 includes a stirring step in which the object to be bleached and the bleaching solution are stirred, or a stimulus application step in which a mechanical stimulus is applied. Instead of or in addition to the stirring step or stimulus application step, a relative movement step in which the bleaching solution is moved relative to the surface of the object to be bleached may be performed. In the relative movement step, the bleaching solution moves relative to the surface of the object to be bleached, thereby supplying relatively fresh, unused bleaching solution to the surface of the object to be bleached and providing a stimulus associated with the movement of the bleaching solution. This is expected to promote bleaching of the disperse dye.

[0062] For example, in the decolorizing step S1, when a relative movement step is performed instead of or in addition to the stirring step or stimulus application step, new or recycled decolorizing solution may be supplied to the first treatment tank, and excess decolorizing solution may be discharged from the first treatment tank. This creates a flow of decolorizing solution within the first treatment tank, causing the decolorizing solution to move relative to the object to be decolorized. In this case, the used decolorizing solution discharged from the first treatment tank may be resupplied to the first treatment tank. That is, the decolorizing solution may be circulated. In this case, the decolorizing solution may be circulated while removing impurities from the decolorizing solution. Examples of impurities include foreign matter and disperse dyes dissolved in the decolorizing solution, specifically disperse dye pigments. Impurities can be removed by, for example, filtering the decolorizing solution using activated carbon or by distilling the decolorizing solution.

[0063] (Modification 1-1-3) In the first embodiment and the above-described modifications, in the bleaching step S1, used bleaching liquid from which impurities have been removed may be used instead of new bleaching liquid.

[0064] For example, the waste bleaching solution generated in the bleaching step S1 may be collected after each bleaching treatment, and after impurities have been removed, it may be used in the next bleaching step S1 or rinsing step S2.

[0065] Furthermore, for example, the decolorizing step S1 may be performed using a decolorizing solution that is circulated through the first treatment tank and from which impurities have been removed during the circulation process. That is, the decolorizing step S1 may be performed while removing impurities from the decolorizing solution. For example, in the decolorizing step S1, excess decolorizing solution may be discharged from the first treatment tank, impurities may be removed from the discharged decolorizing solution, and the resulting decolorizing solution may be supplied back to the first treatment tank.

[0066] (Variation 1-1-4) In the first embodiment, the example is given of the case where the object to be bleached is washed with a bleaching solution having a predetermined bleaching temperature in a first treatment tank containing the bleaching solution in the bleaching step S1. If the object to be bleached can be washed with a bleaching solution having a predetermined bleaching temperature, a treatment tank does not need to be used.

[0067] For example, the bleaching step S1 may be performed by spraying a bleaching solution at the bleaching temperature in a liquid or gaseous state onto the object to be bleached. For example, the bleaching solution may be sprayed onto the object to be bleached at the bleaching temperature as vapor, droplets, or mist using a steamer or atomizer, particularly a high-pressure steamer or atomizer. When the vapor of the bleaching solution heated to the bleaching temperature is sprayed onto the object to be bleached, the object is heated by the vapor of the heated bleaching solution. This can be expected to have the same effect as the heating step described above. Furthermore, since the spraying of the bleaching solution mechanically stimulates the object to be bleached, the same effects as the stirring step and stimulus application step described above can be expected. In particular, it is preferable to spray the vapor, droplets, or mist of the bleaching solution at high pressure and with force in order to increase the mechanical stimulus applied to the object to be bleached and the strength of the flow of the bleaching solution on the surface of the object to be bleached. In other words, by spraying the bleaching liquid as a liquid or gas onto the object to be bleached at the bleaching temperature, both the heating step of heating the object to be bleached and the stimulus application step of applying a mechanical stimulus to the object to be bleached can be performed.

[0068] (Variation 1-1-5) In the first embodiment and the above-described variations, the bleaching step S1 includes the heating step, the stirring step, the stimulus application step, and the relative movement step. However, the stirring step, the stimulus application step, and the relative movement step may be omitted. In this case, the bleaching temperature may be increased and / or the time that the object to be bleached is in contact with the bleaching solution may be longer than in the case of the stirring step, the stimulus application step, or the relative movement step.

[0069] (Modification 1-2) The rinsing step S2 can be realized by any method as long as it brings the bleaching solution at a temperature lower than the fiber-opening temperature into contact with the object to be bleached (fibers of the object to be bleached).

[0070] (Variation 1-2-1) The rinsing step S2 can be performed in the same manner as the bleaching step S1, except that a cooling step is performed instead of a heating step. Therefore, the above-described variations on the bleaching step S1 can also be applied to the rinsing step S2, except that a cooling step is performed instead of a heating step.

[0071] In addition, if the stirring step, stimulus application step, or relative movement step is omitted in the rinsing step S2, the time during which the object to be bleached is in contact with the bleaching solution in the cooling step may be longer than when the stirring step, stimulus application step, or relative movement step is performed.

[0072] The methods of applying mechanical stimuli to the object to be bleached in the bleaching step S1 and the rinsing step S2 may be the same or different, or the stirring step and the stimulus application step may be omitted in one or both steps. The same applies to the methods of moving the bleaching solution relative to the object to be bleached in the bleaching step S1 and the rinsing step S2.

[0073] (Modification 1-2-2) In the first embodiment and the above-described modifications, the bleaching step S1 and the rinsing step S2 are performed in separate treatment tanks, but they may also be performed in the same treatment tank. For example, after the bleaching step S1, the bleaching solution may be discharged from the first treatment tank, and new bleaching solution at a temperature lower than the fiber-spreading temperature may be poured into the first treatment tank, followed by the stirring step, the stimulus application step, or the relative movement step.

[0074] (Modification 1-2-3) Furthermore, if the object to be bleached is sufficiently bleached in the bleaching step S1, the rinsing step S2 may be omitted.

[0075] (Modification 1-3) The bleaching step S1 and / or the rinsing step S2 may be performed multiple times.

[0076] (Variation 1-4) In the first embodiment and the above-described variations, the same type of liquid, for example, a bleaching solution with the same composition, is used in the bleaching step S1 and the rinsing step S2. However, bleaching solutions with different compositions may be used in the bleaching step S1 and the rinsing step S2. For example, the bleaching solution used in the rinsing step S2 may be the same as the bleaching solution used in the bleaching step S1, but may contain a different concentration of a solvent that dissolves the pigment of the disperse dye.

[0077] Furthermore, when the bleaching step S1 is performed multiple times, the same bleaching solution may be used in each bleaching step S1, or different bleaching solutions may be used in all bleaching steps S1. Similarly, a different bleaching solution may be used in at least one bleaching step S1 than the bleaching solution used in the other bleaching steps S1. The above-described use of the bleaching solution can also be applied when the rinsing step S2 is performed multiple times, or when both the bleaching step S1 and the rinsing step S2 are performed multiple times.

[0078] (Variation 1-5) Furthermore, the decolorization of the disperse dye pigment from the object to be bleached is completed by both the bleaching step S1 and the rinsing step S2, or by only the bleaching step S1. Therefore, the dewatering step S3 and the drying step S4 may be performed as needed, and at least one of the dewatering step S3 and the drying step S4 may be omitted. For example, if the entire object to be bleached is to be re-dyed by an exhaust dyeing method after bleaching, the dewatering step S3 and the drying step S4 may be omitted, and the dewatering step S3 and the drying step S4 may be performed only once after the re-dyeing to dehydrate and dry the bleached object after re-dyeing.

[0079] (Variations 1-6) In the first embodiment and the above-described variations, a disperse dye pigment used to dye or color an object to be bleached is decolorized from polyester or nylon fibers contained in the object using a bleaching solution. It is also possible to bleach other dyes other than disperse dyes used to dye or color an object to be bleached. It is also possible to bleach other fibers that can retain disperse dyes or other dye pigments in the gaps between the molecular chains of the fibers, rather than polyester or nylon fibers. Any bleaching solution can be used as long as it can remove the pigments, such as the dyes retained in the gaps between the molecular chains of the fibers, and decolorize the fibers. Furthermore, for example, the bleaching solution may contain a bleaching agent or a bleaching solution that bleaches the pigments of dyes. Here, bleaching a pigment means, for example, decomposing and removing the pigment or discoloring the pigment to make it less noticeable. Making the pigment less noticeable means, for example, making the color of the fiber closer to white or closer to the original color of the fiber. Examples of bleaching agents include oxidative bleaching agents such as chlorine bleaching agents and oxygen bleaching agents, and reductive bleaching agents. Furthermore, when the bleaching solution contains a bleaching agent that discolors the pigment to make it less noticeable, the fiber-spreading temperature may be any temperature at which the gaps in the molecular chains of the fiber widen and the molecular chains loosen to an extent that the active ingredient of the bleaching agent can easily access the pigment of the dye present in the gaps in the molecular chains. Therefore, the fiber-spreading temperature may be any temperature at which the molecular chains of the fiber contained in the object to be bleached loosen.

[0080] Second Embodiment A bleaching device 100 according to a second embodiment of the present invention will be described. The bleaching device 100 can suitably perform the bleaching method according to the first embodiment.

[0081] (Configuration of Bleaching Apparatus 100) As shown in Figures 2 and 3, the bleaching apparatus 100 includes a sealed housing 10, a conveying section 20, a bleaching section 30, a rinsing section 40, an exhaust device 50, a fume recovery device 60, and a control section 70.

[0082] The sealed housing 10 houses the conveying section 20, the bleaching section 30, and the rinsing section 40. The sealed housing 10 is designed to be sealed so that fumes generated from the bleaching section 30 and the rinsing section 40 do not leak to the outside except through a predetermined path such as an exhaust device 50. The sealed housing 10 has an entrance 11 that is opened when the object 1 to be bleached is carried into the sealed housing 10, and an exit 12 that is opened when the object 1 to be bleached is carried out of the sealed housing 10 after bleaching.

[0083] The transport unit 20 transports the bleaching object 1 through the bleaching process. The transport unit 20 includes a rail 21, a robot base 22 that moves on the rail 21, and a robot arm 23 that can grasp the bleaching object 1. The rail 21 is provided in a range from above a predetermined position where the transport box 5 is placed, across above the bleaching unit 30 and above the rinsing unit 40, to above a predetermined position where the collection box 6 is placed. The transport box 5 contains the bleaching object 1 to be bleached in a folded state. The collection box 6 contains the bleaching object 1 after bleaching. The robot arm 23 is provided on the robot base 22. The robot arm 23 moves along the rail 21 together with the robot base 22.

[0084] In the decolorizing section 30, the object to be decolorized is washed with the decolorizing solution 2 in a treatment tank containing the decolorizing solution 2 at a predetermined decolorizing temperature. As shown in Figure 4, the decolorizing section 30 includes a first treatment tank 31, a first storage tank 32, a first supply piping system 33, a first waste liquid tank 34, a first discharge piping system 35, a first impurity removal device 36, and a heating device 37.

[0085] The first treatment tank 31 includes a cylindrical outer tank 31a with an open top, a cylindrical inner tank 31b with an open top, and a motor 31c. The inner tank 31b is housed within the outer tank 31a. The motor 31c is located below the outer tank 31a and the inner tank 31b. The motor 31c drives the inner tank 31b. The outer tank 31a and the inner tank 31b are made of stainless steel. The outer tank 31a is fluidly connected to the first storage tank 32 via a first supply piping system 33. Furthermore, the outer tank 31a is fluidly connected to the first waste liquid tank 34 via a first discharge piping system 35. During the decolorization treatment, the outer tank 31a is filled with the decolorizing solution 2 supplied from the first storage tank 32 via the first supply piping system 33. The inner tank 31b has a plurality of through-holes through which the decolorizing solution 2 passes. During the bleaching treatment, the inner tank 31b is filled with the bleaching solution 2 that enters through the through-hole. Furthermore, during the bleaching treatment, the object 1 to be bleached is loaded into the inner tank 31b by the conveying unit 20. The motor 31c has a drive shaft that passes watertight through the center of the bottom of the outer tank 31a. The drive shaft is connected to the center of the bottom of the inner tank 31b. During the bleaching treatment, the motor 31c rotates the inner tank 31b around a vertical axis that passes through the center of the bottom of the inner tank 31b. This causes the object 1 to be bleached and the bleaching solution 2 in the first treatment tank 31 to be agitated.

[0086] The first storage tank 32 stores the decolorizing solution 2. The decolorizing solution 2 stored in the first storage tank 32 is supplied to the first treatment tank 31 via a first supply piping system 33.

[0087] The first supply piping system 33 includes a supply piping 33a through which the decolorizing solution 2 to be supplied to the first treatment tank 31 passes, a supply valve 33b, and a supply pump 33c that supplies the decolorizing solution 2. The supply valve 33b is an electromagnetic valve that controls the supply of the decolorizing solution 2 to the first treatment tank 31.

[0088] The first waste liquid tank 34 stores the used decolorizing solution 2 discharged from the first treatment tank 31 via the first discharge piping system 35 .

[0089] The first discharge piping system 35 includes a discharge pipe 35a through which the used decolorizing solution 2 discharged from the first treatment tank 31 passes, and a discharge valve 35b. The discharge valve 35b is an electromagnetic valve that controls the discharge of the decolorizing solution 2 from the first treatment tank 31.

[0090] The first impurity removal device 36 is an activated carbon filtration device. The first impurity removal device 36 is provided to remove disperse dyes, specifically, pigments of disperse dyes, dissolved in the bleaching solution 2 discharged from the first treatment tank 31. The first impurity removal device 36 includes a cartridge-type activated carbon filter. The activated carbon filter can be replaced as needed or periodically.

[0091] The heating device 37 heats the decolorizing solution 2 in the first treatment tank 31 to a decolorizing temperature. The heating device 37 is an induction heater (IH) or a radiant heater. The heating device 37 is disposed around the side surface of the cylindrical outer tank 31 a of the first treatment tank 31.

[0092] In the rinsing section 40, the object to be bleached is rinsed with the bleaching solution in a treatment tank containing the bleaching solution at a temperature lower than a predetermined fiber-opening temperature. The temperature of the bleaching solution at this time is, for example, about 20°C or 25°C, which corresponds to room temperature. As shown in Fig. 5, the rinsing section 40 includes a second treatment tank 41, a second storage tank 42, a second supply piping system 43, a second waste liquid tank 44, a second discharge piping system 45, and a second impurity removal device 46. The configurations of the second treatment tank 41, the second storage tank 42, the second supply piping system 43, the second waste liquid tank 44, the second discharge piping system 45, and the second impurity removal device 46 are similar to the configurations of the first treatment tank 31, the first storage tank 32, the first supply piping system 33, the first waste liquid tank 34, the first discharge piping system 35, and the first impurity removal device 36 described above, respectively, and therefore will not be described here.

[0093] 3, the exhaust device 50 is provided to exhaust fumes (vapors) of the bleaching solution 2 generated from the bleaching section 30 and the rinsing section 40 to the outside of the sealed housing 10. The exhaust device 50 includes an exhaust duct 51 and an exhaust fan 52.

[0094] The fume recovery device 60 is disposed midway through the exhaust duct 51 of the exhaust device 50. The fume recovery device 60 recovers the fumes of the decolorizing solution 2 passing through the exhaust device 50 by returning them to a liquid. The fume recovery device 60 includes an electronic cooler that condenses the fumes on its surface, and a recovery tank that collects the condensation dripping from the surface of the electronic cooler.

[0095] The control unit 70 controls the transport unit 20, the bleaching unit 30, the rinsing unit 40, the exhaust device 50, and the fume recovery device 60 to perform a bleaching process for bleaching the object 1 to be bleached and a recovery process for recovering the bleaching liquid 2.

[0096] To perform the bleaching process and the recovery process, the control unit 70 includes a storage device (hard disk, flash memory, etc.) that stores programs and various data, a processor (CPU (Central Processing Unit), etc.) that executes the programs stored in the storage device, a main memory for the processor, and various interfaces. The control unit 70 may be, for example, a personal computer.

[0097] (Bleaching Process) First, when the transport box 5 containing the folded bleaching objects 1 to be bleached is carried into a predetermined position outside the sealed housing 10, the control unit 70 executes the following procedure: (a) controls the conveying unit 20 to move the robot base 22 above the transport box 5; (b) controls the robot arm 23 to grasp and lift at least one of the bleaching objects 1 in the transport box 5; (c) moves the robot base 22 above the first treatment tank 31 of the bleaching unit 30; (d) drops the bleaching object 1 grasped by the robot arm 23 into the first treatment tank 31. This places the bleaching object 1 in the first treatment tank 31 of the bleaching unit 30. Note that during the process of moving the robot base 22 above the first treatment tank 31, the control unit 70 controls the opening and closing mechanism of the sealed housing 10 to open and close the entrance 11. As a result, the object 1 to be bleached is carried into the sealed housing 10 by the robot arm 23. The transport box 5 is carried into the predetermined position by an operator or an automatic supply device such as a self-propelled wagon.

[0098] When the object 1 to be bleached is placed in the first treatment tank 31, the control unit 70 controls the supply valve 33b and supply pump 33c of the first supply piping system 33 of the bleaching unit 30 to fill the first treatment tank 31 with the bleaching solution 2. Next, the control unit 70 controls the heating device 37 to heat the bleaching solution in the first treatment tank 31 to a predetermined bleaching temperature. Once the bleaching solution has been heated to the predetermined bleaching temperature, the control unit 70 controls the motor 31c of the first treatment tank 31 to rotate the inner tank 31b for a predetermined time. This agitates the object 1 to be bleached and the bleaching solution 2.

[0099] After a predetermined time has elapsed, the control unit 70 stops the rotation of the inner tank 31b of the first treatment tank 31. Next, the control unit 70 performs the following procedure to move the object to be bleached 1 into the second treatment tank 41: (a) controls the robot arm 23 to grasp and lift the object to be bleached 1 in the first treatment tank 31; (b) moves the robot base 22 to above the second treatment tank 41 of the rinsing unit 40; (c) drops the object to be bleached 1 grasped by the robot arm 23 into the second treatment tank 41. This causes the object to be bleached 1 to be placed in the second treatment tank 41 of the rinsing unit 40.

[0100] When the object 1 to be bleached is placed in the second treatment tank 41, the control unit 70 controls the supply valve 43b and supply pump 43c of the second supply piping system 43 of the rinsing unit 40 to fill the second treatment tank 41 with the bleaching solution 2. At this time, the bleaching solution 2 at room temperature or normal temperature is supplied to the second treatment tank 41. Next, the control unit 70 controls the motor 41c of the second treatment tank 41 to rotate the second inner tank 41b for a predetermined time. This agitates the object 1 to be bleached and the bleaching solution 2.

[0101] After a predetermined time has elapsed, the control unit 70 stops the rotation of the second inner tank 41b of the second treatment tank 41. The control unit 70 then carries the following procedure to transport the bleaching target 1 to the collection box 6 in the sealed housing 10: (a) controls the robot arm 23 to grasp and lift the bleaching target 1 in the second treatment tank 41; (b) controls the transport unit 20 to move the robot base 22 above the collection box 6, which is located at a predetermined position outside the sealed housing 10; and (c) drops the bleaching target 1 grasped by the robot arm 23 into the collection box 6. This deposits the bleached bleaching target 1 into the collection box 6. During the process of moving the robot base 22 above the collection box 6, the control unit 70 controls the opening / closing mechanism of the sealed housing 10 to open and close the outlet 12. This causes the bleached bleaching target 1 to be transported to the outside of the sealed housing 10 by the robot arm 23.

[0102] Thereafter, the collection box 6 containing the decolorized object 1 is transported to a deliquifying device by an operator or an automatic supply device such as a self-propelled wagon. In the deliquifying device, the deliquifying process (dehydration process) of the decolorized object 1 is performed. Next, the deliquified object 1 is transported to a drying device by an operator or an automatic supply device such as a self-propelled wagon. In the drying device, the decolorized object 1 is dried to remove any liquid components (moisture) remaining in the decolorized object 1.

[0103] (Recovery Process) In the above-described decolorizing process, when the object 1 to be decolorized is removed from the first treatment tank 31, the control unit 70 controls the first discharge piping system 35 of the decolorizing unit 30 to discharge the decolorizing liquid 2 (used decolorizing liquid) in the first treatment tank 31 into the first waste liquid tank 34. During this process, the used decolorizing liquid 2 passes through the first impurity removal device 36. At this time, the disperse dye contained in the decolorizing liquid 2, particularly the pigment component of the dye, is removed from the decolorizing liquid 2. As a result, the decolorizing liquid 2 from which the disperse dye has been removed is discharged into the first waste liquid tank 34.

[0104] Furthermore, in the above-described rinsing process, when the object 1 to be decolorized is removed from the second treatment tank 41, the control unit 70 controls the second discharge piping system 45 of the rinsing unit 40 to discharge the decolorizing solution 2 (used decolorizing solution) in the second treatment tank 41 into the second waste liquid tank 44. During this process, the used decolorizing solution 2 passes through the second impurity removal device 46. At this time, the disperse dye contained in the decolorizing solution 2, particularly the pigment component of the dye, is removed from the decolorizing solution 2. As a result, the decolorizing solution 2 from which the disperse dye has been removed is discharged into the first waste liquid tank 34.

[0105] During the above-described bleaching and rinsing processes, the control unit 70 controls the exhaust fan 52 of the exhaust device 50 to suck fumes from the bleaching solution 2 generated in the bleaching section 30 and the rinsing section 40 into the exhaust duct 51 and discharge them to the outside of the sealed housing 10. During this process, the control unit 70 controls the electronic cooler of the fume collection device 60 to condense the fumes passing through the exhaust duct 51 on the surface of the electronic cooler. The condensed bleaching solution 2 drips from the surface of the electronic cooler and is ultimately collected in the collection tank of the fume collection device 60.

[0106] The decolorizing solution 2 recovered in the first waste liquid tank 34 of the decolorizing section 30, the decolorizing solution 2 recovered in the second waste liquid tank 44 of the rinsing section 40, and the decolorizing solution 2 recovered in the recovery tank of the fume recovery device 60 all contain almost no disperse dyes or impurities, and even if they contain disperse dyes or impurities, the amount is such that it does not interfere with the use of the decolorizing solution 2 in other decolorizing processes. Therefore, the decolorizing solution 2 recovered in the first waste liquid tank 34, the decolorizing solution 2 recovered in the second waste liquid tank 44 of the rinsing section 40, and the decolorizing solution 2 recovered in the recovery tank of the fume recovery device 60 can be suitably reused in other decolorizing processes.

[0107] (Effects of the Second Embodiment) First, the bleaching device according to the second embodiment has the same effects as the bleaching method according to the first embodiment.

[0108] Furthermore, the decolorization process in the decolorization step S1 and the rinsing process in the rinsing step S2 can be performed automatically in a closed environment without human intervention. When the decolorization process and rinsing process are performed, fumes from the decolorization solution 2 are generated. The fumes from the decolorization solution 2 can be a burden for workers and operators. As described above, by performing the process that generates fumes from the decolorization solution 2 in a closed environment within the sealed housing 10, the object to be decolorized can be decolorized without imposing a laborious or health burden on the user.

[0109] Furthermore, none of the bleaching solution 2 recovered in the first waste liquid tank 34 of the bleaching section 30, the bleaching solution 2 recovered in the second waste liquid tank 44 of the rinsing section 40, and the bleaching solution 2 recovered in the recovery tank of the fume recovery device 60 contains disperse dyes or impurities, and even if they do contain disperse dyes or impurities, the amount is such that it does not interfere with the reuse of the bleaching solution 2. This allows the recovered bleaching solution 2 to be reused for other bleaching processes or rinsing processes, thereby reducing environmental and economic burdens.

[0110] (Modification 2-1) The configuration of the decolorizing device 100, particularly the configuration of the decolorizing unit 30, is arbitrary as long as it can perform the decolorizing step S1 of the first embodiment and its modifications.

[0111] For example, in the second embodiment, the first treatment tank 31 is illustrated as being composed of a cylindrical outer tank 31a and an inner tank 31b. The first treatment tank 31 is not limited to the above-described embodiment. For example, the first treatment tank 31 may include only the outer tank 31a without the inner tank 31b. The shape of the first treatment tank 31 is not limited to a cylindrical shape and may be other shapes, such as a rectangular shape. For example, the first treatment tank 31 may be a deep or shallow box-shaped treatment tank with an open top. The material of the first treatment tank 31 is not limited to stainless steel and may be other materials, such as glass or heat-resistant and solvent-resistant resin.

[0112] The first impurity removal device 36 may also be omitted. In this case, the decolorizing solution 2 stored in the first waste solution tank 34 may be transported outside the sealed housing 10 and subjected to a regeneration process such as filtration or distillation.

[0113] (Variation 2-1-1) In the second embodiment, the inner tank 31b of the first treatment tank 31 in the bleaching unit 30 is rotated to agitate the object to be bleached 1 and the bleaching solution 2. A stirring method other than the stirring method exemplified above may be used as long as it can remove the pigment of the disperse dye from the object to be bleached 1. Furthermore, a mechanical stimulus may be applied to the object to be bleached 1 by a method other than agitation.

[0114] For example, as another stirring method, a motor-driven stirring blade may be provided to stir the mixture. In this case, an example is to provide a motor-driven stirring blade on the bottom of the outer tank 31a or the bottom of the inner tank 31b of the first treatment tank 31. Furthermore, as another stirring method, a magnetic stirrer or an electromagnetic stirrer may be used to stir the mixture. In this case, an example is to place a magnetic stirrer or an electromagnetic stirrer on the bottom of at least one of the outer tank 31a and the inner tank 31b of the first treatment tank 31 to stir the mixture. Furthermore, convection can be generated by vibrating the entire first treatment tank 31 (outer tank 31a, inner tank 31b) or by using a pump.

[0115] Furthermore, examples of stimulation devices that apply mechanical stimulation to the object to be bleached 1 include a shaking device that shakes the bleaching solution 2 together with the object to be bleached 1 in the first treatment tank 31, an ultrasonic treatment device that ultrasonically treats the bleaching solution 2 together with the object to be bleached 1 in the first treatment tank 31, and a motor-driven stirring blade that is positioned so as to come into contact with the object to be bleached 1 in the first treatment tank 31.

[0116] (Variation 2-1-2) In the second embodiment and the above-described variations, examples have been given of cases in which the bleaching unit 30 promotes bleaching by stirring the object to be bleached 1 and the bleaching solution 2 or by applying a mechanical stimulus to the object to be bleached 1 and the bleaching solution 2. Instead of or in addition to stirring or stimulating, the stimulus may be applied by moving the bleaching solution 2 relative to the surface of the object to be bleached 1.

[0117] For example, in the second embodiment, the decolorizing unit 30 replaces the decolorizing solution 2 in the first treatment tank 31 with new decolorizing solution 2 each time the decolorizing process is completed. Alternatively, new decolorizing solution 2 or recovered and reused decolorizing solution 2 may be continuously supplied to the first treatment tank 31, and the decolorizing process may be performed while the excess decolorizing solution 2 is discharged from the first treatment tank 31. In this case, the used decolorizing solution 2 discharged from the first treatment tank 31 may be resupplied to the first treatment tank 31. That is, the decolorizing solution 2 may be circulated for use. To achieve this, for example, the first discharge piping system 35 may be connected to the first storage tank 32 instead of the first waste liquid tank 34, so that the decolorizing solution 2 is circulated. Alternatively, a separate discharge piping system may be provided connecting the first treatment tank 31 and the first storage tank 32, so that the decolorizing solution 2 is circulated. In this case, in order to improve the flow of the decolorizing solution 2, the first discharge piping system 35 or the newly provided separate discharge piping system may not be provided with an impurity removal device.

[0118] Furthermore, for example, one or more nozzles for spraying the bleaching liquid 2 may be provided to cause relative movement of the bleaching liquid 2 relative to the surface of the object to be bleached 1. In this case, the nozzles may be provided to form a vortex within the first treatment tank 31. For example, a vortex can be formed by providing a nozzle for spraying the bleaching liquid 2 along the normal direction of the outer circumferential circle of the vortex to be formed. For example, in the second embodiment, the outer tank 31a of the first treatment tank 31 is substantially circular when viewed from above. Therefore, for example, one or more nozzles for spraying the bleaching liquid 2 may be provided on the circular bottom of the outer tank 31a when viewed from above. In this case, the nozzles are configured to receive the bleaching liquid 2 from the first supply piping system 33, and are provided at a position radially spaced from the center of the bottom so that the sprayed bleaching liquid 2 obliquely strikes the inner circumferential surface (side surface) of the outer tank 31a. With this configuration, when the decolorizing liquid 2 is supplied into the first treatment tank 31 through the nozzle, a vortex flow is generated within the first treatment tank 31, which can cause the decolorizing liquid 2 to move relative to the surface of the object 1 to be decolorized.

[0119] Furthermore, for example, when a deep or shallow box-shaped treatment tank with an open top is used as the first treatment tank 31, the following may be done to bring about relative movement of the bleaching solution 2 with respect to the surface of the object 1 to be bleached: a first supply piping system 33 is opened at one end in the longitudinal direction of the box-shaped treatment tank, and a first discharge piping system 35 is opened at the other end, so that the bleaching solution 2 flows from one end to the other end within the treatment tank.

[0120] (Variation 2-1-3) In the second embodiment and the above-described variations, in the bleaching unit 30, instead of new bleaching liquid 2, a used bleaching liquid 2 from which impurities, particularly disperse dyes, and in particular the pigments of disperse dyes, have been removed may be used.

[0121] For example, waste decolorizing solution 2 generated in the decolorizing unit 30 may be recovered each time a decolorizing process is performed, and impurities may be removed from the recovered decolorizing solution 2. The decolorizing solution from which impurities have been removed may then be reused in the decolorizing unit 30 or the rinsing unit 40 in the next decolorizing process. For example, to automatically reuse the decolorizing solution, as shown in FIG. 6 , the first supply piping system 33 may include a supply pipe 33d connecting a region of the supply pipe 33a upstream of the supply pump 33c to the first waste tank 34. In this case, a supply valve 33e may be provided between the region of the supply pipe 33a where the supply pipe 33d branches and the first storage tank 32, and a supply valve 33f may be provided on the supply pipe 33d. In this case, when new decolorizing solution 2 is used, the supply valves 33b and 33e are opened, the supply valve 33f is closed, and the supply pump 33c is operated to supply the decolorizing solution 2 from the first storage tank 32 to the first treatment tank 31. On the other hand, when using decolorizing solution 2 from which impurities have been removed, supply valves 33b and 33f are opened, supply valve 33e is closed, and supply pump 33c is operated to supply decolorizing solution 2 from which impurities have been removed from the first waste liquid tank 34 to the first treatment tank 31.

[0122] Also, for example, the decolorizing step S1 may be configured so that the decolorizing solution is recycled in the first treatment tank 31, and after impurities are removed from the decolorizing solution recovered from the first treatment tank 31, the decolorizing solution may be supplied to the first treatment tank 31. For example, in the decolorizing step S1, excess decolorizing solution may be discharged from the first treatment tank, impurities may be removed from the discharged decolorizing solution, and the decolorizing solution may be supplied again to the first treatment tank.

[0123] (Variation 2-1-4) Furthermore, for example, the decolorizing unit 30 may include a spraying device, instead of the first treatment tank 31, that sprays the decolorizing liquid 2 onto the object to be decolorized 1. In this case, the spraying device sprays the decolorizing liquid at the decolorizing temperature in a liquid or gaseous state onto the object to be decolorized. Examples of the spraying device include a steamer or an atomizer, particularly a high-pressure steamer or a high-pressure atomizer. In this case, the first supply piping system 33 is connected to the spraying device, and the first discharge piping system 35 is connected to a waste liquid outlet under the floor of the sealed housing 10 instead of the first treatment tank 31. For example, the decolorizing liquid 2 is sprayed from the spraying device in a liquid or gaseous state onto the object to be decolorized 1 held by the robot arm 23 of the transport unit 20. Droplets of the decolorizing liquid 2 that drip from the object to be decolorized 1 are discarded through a waste liquid outlet and stored in the first waste liquid tank 34.

[0124] (Variation 2-1-5) In the second embodiment and the above-described variations, the bleaching unit 30 is configured to agitate the object to be bleached 1 and the bleaching solution 2, apply mechanical stimulation to the object to be bleached 1, and move the bleaching solution 2 relative to the object to be bleached 1. These configurations may be omitted. In this case, when the bleaching unit 30 performs the heating step of the bleaching step S1, the bleaching temperature may be increased and / or the time that the object to be bleached 1 is in contact with the bleaching solution 2 may be increased compared to when these configurations are omitted.

[0125] (Variation 2-1-6) In the second embodiment and the above-described variations, the first impurity removal device 36 is used. When removing impurities from the used bleaching solution 2, the first impurity removal device 36 only needs to have the performance to remove disperse dyes and disperse dye pigments contained in the bleaching solution 2 to an extent that they can be reused in the bleaching process. Therefore, a filtration device using activated carbon or a distillation device that removes impurities by distillation can be used.

[0126] (Variation 2-1-7) In the second embodiment and the above-described variations, the heating device 37 is used. The configuration of the heating device 37 is arbitrary as long as it can heat the bleaching solution 2 to the bleaching temperature. In addition to an induction heater (IH) or a radiant heater, for example, an oil bath or an immersion heater may also be used. Furthermore, the heating device 37 may be arranged to heat the first storage tank 32 instead of or in addition to the first treatment tank 31 or the spray device.

[0127] (Variation 2-1-8) In the second embodiment and the above-described variations, a lid configured to open and close automatically may be provided on the first treatment tank 31 of the bleaching unit 30. This lid is opened when the object 1 to be bleached is placed in the first treatment tank 31, and is closed until the bleaching treatment in the bleaching unit 30 is completed. This reduces the amount of fumes leaking from the first treatment tank 31 of the bleaching unit 30.

[0128] (Modification 2-2) The configuration of the rinsing unit 40 is arbitrary as long as it can perform the rinsing step S2 of the first embodiment and its modifications.

[0129] (Variation 2-2-1) The rinsing unit 40 can be configured in the same manner as the bleaching unit 30, except for the temperature at which the bleaching solution is used and the presence or absence of the heating device 37. Therefore, except for the temperature at which the bleaching solution is used and the presence or absence of the heating device 37, the above-mentioned variations regarding the bleaching unit 30 can also be applied to the rinsing unit 40.

[0130] Note that the rinsing unit 40 may omit the configurations for stirring the object to be bleached 1 and the bleaching solution 2, applying mechanical stimulation to the object to be bleached 1, and moving the bleaching solution 2 relative to the object to be bleached 1. In such a case, when the rinsing unit 40 performs the cooling step of the rinsing step S2, the time during which the object to be bleached 1 is in contact with the bleaching solution 2 may be longer than when the configurations are omitted.

[0131] Furthermore, the method of applying mechanical stimulation to the bleaching target 1 in the bleaching unit 30 and the rinsing unit 40 may be the same or different. At least one of the bleaching unit 30 and the rinsing unit 40 may omit the configuration of agitating the bleaching target 1 and the bleaching solution 2, applying mechanical stimulation to the bleaching target 1, or moving the bleaching solution 2 relative to the bleaching target 1.

[0132] (Variation 2-2-2) The rinsing section 40 may also include a cooling device that cools at least one of the second treatment tank 41 and the second storage tank 42. The temperature of the object 1 to be bleached that is introduced into the rinsing section 40 is high due to being immersed in the bleaching solution in the bleaching section 30. Therefore, if the object 1 to be bleached is frequently introduced from the bleaching section 30 into the rinsing section 40, the temperature of the bleaching solution 2 in the rinsing section 40 may become high. By providing a cooling device, it is possible to reduce the possibility that the temperature of the bleaching solution 2 in the rinsing section 40 will exceed the fiber-opening temperature. This makes it possible to maintain the efficiency of bleaching in the rinsing section 40.

[0133] (Modification 2-2-3) Instead of or in addition to the rinsing unit 40, the decolorizing unit 30 may perform the rinsing step S2.

[0134] For example, after the bleaching step S1 is performed in the bleaching unit 30, the bleaching solution 2 is discharged from the first treatment tank 31, and then the bleaching solution having a temperature lower than the fiber-spreading temperature is supplied from the first storage tank 32 to the bleaching unit 30. Then, the agitation step, the stimulus application step, or the relative movement step may be performed in the bleaching unit 30 filled with the bleaching solution having a temperature lower than the fiber-spreading temperature.

[0135] (Modification 2-1-4) Furthermore, if the bleaching target is sufficiently bleached in the bleaching section 30, the rinsing section 40 may be omitted.

[0136] (Variation 2-3) A plurality of bleaching sections 30 and / or rinsing sections 40 may be provided. For example, in order to increase the processing volume per unit time, the bleaching step S1 may be performed in parallel in a plurality of bleaching sections 30. In order to achieve more complete bleaching, the object 1 to be bleached may pass through a plurality of bleaching sections 30 in sequence, and the bleaching step S1 may be performed in each of the bleaching sections 30. The same applies to the rinsing section 40.

[0137] (Variation 2-4) In the second embodiment and the above-described variations, the bleaching solution 2 having the same composition is used in the bleaching unit 30 and the rinsing unit 40. However, the bleaching solution 2 having a different composition may be used in the bleaching unit 30 and the rinsing unit 40. For example, the bleaching solution used in the rinsing unit 40 may be the same as the bleaching solution 2 used in the bleaching unit 30, but may contain a solvent that dissolves the pigment of the disperse dye at a different concentration.

[0138] Furthermore, when a plurality of bleaching units 30 are provided, the bleaching solution 2 used in each bleaching unit 30 may be the same, or a bleaching solution 2 with a different composition may be used in at least one bleaching unit 30. The same applies when a plurality of rinsing units 40 are provided, or when a plurality of both bleaching units 30 and rinsing units 40 are provided.

[0139] (Variant 2-5) The configuration of the sealed housing 10 is arbitrary as long as it is designed to be sealed so that fumes generated from the bleaching section 30 and the rinsing section 40 do not leak to the outside through any route other than a specified route such as the exhaust device 50.

[0140] For example, air curtains may be provided at the entrance 11 and the exit 12 of the sealed housing 10. This makes it possible to prevent fumes from leaking from the entrance 11 and the exit 12 when the transport unit 20 transports the object 1 to be bleached. Furthermore, even if fumes leak, the amount of leakage can be suppressed.

[0141] (Variation 2-6) As shown in Fig. 7, instead of the sealed housing 10, a hood 80 may be provided to cover the openings through which fumes are released from the bleaching unit 30 and the rinsing unit 40. This configuration also allows the bleaching step S1 and the rinsing step S2, which generate potentially harmful fumes from the bleaching solution 2, to be performed automatically without human intervention while at least reducing the amount of fumes that diffuse into the surrounding area. This allows the bleaching target to be bleached without burdening the user.

[0142] In addition, in order to shorten the distance between the hood 80 and the openings through which fumes from the bleaching section 30 and the rinsing section 40 are released, the conveying section 20 may be positioned to the side of the hood 80, as shown in Figure 7, so that the bleaching section 30 and the rinsing section 40 can be accessed through the gap between the hood 80 and the openings.

[0143] The hood 80 may also be separately positioned above the bleaching section 30, the rinsing section 40, or any other device that may generate harmful substances.

[0144] (Modification 2-7) The exhaust device 50 may have any configuration as long as it can exhaust the fumes of the bleaching solution 2 generated from the bleaching section 30 and the rinsing section 40.

[0145] (Variation 2-8) The fume recovery device 60 may have any configuration as long as it can recover the fumes of the decolorizing solution 2 passing through the exhaust device 50 by returning them to a liquid state. For example, if the fumes of the decolorizing solution 2 condense on the inner surface of the exhaust duct 51 of the exhaust device 50, the bottom of the horizontally extending part of the exhaust duct 51 may be formed into a funnel shape, and the tip of the funnel may be connected to a recovery device such as a recovery bottle via a drain. In this case, the fumes that have been returned to a liquid state can be recovered in the recovery device.

[0146] (Variation 2-9) At least one of the deliquifying device and the drying device may be provided inside the sealed housing 10 or under the hood 80. In addition, other devices required for pre-treatment and post-treatment of decolorization may be provided inside the sealed housing 10 or under the hood 80.

[0147] (Variation 2-10) The transport unit 20 may be configured to be capable of loading and unloading the object 1 to and from the bleaching unit 30 and the rinsing unit 40. For example, the transport unit 20 may be configured to have a work holding mechanism attached to a turntable that can be moved up and down, such as a tenter clip. Furthermore, if a deliquor device, a drying device, or other device is provided inside the sealed housing 10 or under the hood 80, the transport unit 20 may be configured to transport the object 1 to those devices and hang the object 1 on those devices.

[0148] (Modification 2-11) The decolorizing device 100 is constructed to explosion-proof specifications.

[0149] Example 1 A color chart test pattern was printed on a 60 cm x 60 cm polyester fabric (Tropical (product name)) using a direct sublimation printing device (Tiger 600-1800TS (product name) manufactured by Mimaki Engineering Co., Ltd.) with a disperse dye (Sb510 (product name) manufactured by Mimaki Engineering Co., Ltd.). The polyester fabric was immersed in Newsolve UC in a liquid tank and heated to 160°C for 2 minutes while stirring the solution with a stirrer (100 rpm). Thereafter, the polyester fabric was immersed in Newsolve UC (main components: dimethyl succinate, dimethyl glutarate, and dimethyl adipate) in another beaker and heated to 160°C for 10 seconds while stirring the solution with a stirrer (100 rpm). Finally, the polyester fabric was removed, drained, and dried. The test pattern had completely disappeared from the polyester fabric after bleaching, and there was no deterioration in texture or shrinkage.

[0150] (Example 2) Except for using ethyl acetate diuxol instead of Newsolve UC, a bleaching treatment was carried out in the same manner as in Example 1. In this case as well, the test pattern had completely disappeared from the polyester fabric after bleaching, and there was no deterioration in texture or shrinkage.

[0151] (Example 3) Except for using 3-methoxy-N,N-dimethylpropanamide instead of Newsolv UC, a bleaching treatment was carried out in the same manner as in Example 1. In this case as well, the test pattern had completely disappeared from the polyester fabric after bleaching, and there was no deterioration in texture or shrinkage.

[0152] The present invention allows various embodiments and modifications without departing from the broad spirit and scope of the present invention. Furthermore, the above-described embodiments are intended to explain the invention and do not limit the scope of the invention. That is, the scope of the invention is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of the disclosure equivalent thereto are considered to be within the scope of the invention.

[0153] REFERENCE SIGNS LIST 1 Object to be bleached 2 Bleaching solution 5 Transport box 6 Collection box 10 Sealed housing 11 Inlet 12 Outlet 20 Transport section 21 Rail 22 Robot base 23 Robot arm 30 Bleaching section 31 First treatment tank 32 First storage tank 33 First supply piping system 33a First supply piping 33b, 33d Supply valve 33c, 33e, 33f Supply pump 34 First waste liquid tank 35 First discharge piping system 35a Discharge piping 35b Discharge valve 36 First impurity removal device 37 Heating device 40 Rinse section 41 Second treatment tank 42 Second storage tank 43 Second supply piping system 43a Supply piping 43b Supply valve 43c Supply pump 44 Second waste liquid tank 45 Second discharge piping system 45a Exhaust pipe 45b Exhaust valve 46 Second impurity removal device 50 Exhaust device 51 Exhaust duct 52 Exhaust fan 60 Fume recovery device 70 Control unit 80 Hood 100 Decolorization device

Claims

1. A method for bleaching a pigment of a dye from an object to be bleached, the pigment being held in gaps between molecular chains of the fibers, the method comprising: a bleaching step of washing the object to be bleached with a first bleaching solution having a bleaching temperature equal to or higher than the fiber-opening temperature at which the molecular chains of the fibers contained in the object to be bleached are relaxed to such an extent that the pigment can escape from the gaps between the molecular chains of the fibers.

2. The decolorization method according to claim 1, wherein the dye is a disperse dye, and the fiber is a fiber that can be dyed or colored with the disperse dye.

3. The decolorizing method according to claim 1, wherein in the decolorizing step, the fibers are contacted with the first decolorizing solution at the decolorizing temperature in a treatment tank.

4. The decolorization method according to claim 3, wherein in the decolorization step, the object to be decolorized is carried into the first decolorization solution in the treatment tank containing the first decolorization solution heated to the decolorization temperature.

5. The decolorization method according to claim 3, wherein in the decolorization step, the first decolorization solution is heated to the decolorization temperature in the treatment tank containing the object to be decolorized and the first decolorization solution having a temperature lower than the decolorization temperature.

6. The bleaching method according to claim 3, wherein the bleaching step includes a stimulus application step of applying a mechanical stimulus to the object to be bleached after or during contact of the first bleaching solution with the fiber.

7. The destaining method according to claim 6, wherein the stimulus application step includes any one of a stirring step, a shaking step, and an ultrasonic treatment step for the first destaining solution containing the object to be destained in the treatment tank.

8. The decolorization method according to claim 3, wherein the decolorization step is carried out while supplying new or recycled first decolorization solution to the treatment tank and discharging excess first decolorization solution from the treatment tank.

9. The bleaching method according to claim 1, wherein the bleaching step includes a step of spraying the first bleaching solution as a liquid or gas onto the object to be bleached at the bleaching temperature.

10. The decolorizing method according to claim 1, further comprising a rinsing step of contacting the object to be decolorized with a second decolorizing solution that decolorizes the pigment after the decolorizing step.

11. The destaining method according to claim 10, wherein the second destaining liquid is the same type of liquid as the first destaining liquid.

12. The destaining method according to any one of claims 1 to 11, further comprising a destaining step of destaining the first destaining solution from the object to be destained, and a drying step of drying the object to be destained.

13. The method for decolorizing according to claim 1, wherein the fibers include at least one of polyester fibers and nylon fibers.

14. The decolorizing method according to claim 1, wherein the decolorizing temperature is lower than the boiling point of the first decolorizing solution.

15. A bleaching device for bleaching a pigment of a dye from a bleaching object containing fibers dyed or colored with the dye, comprising: a bleaching section for washing the bleaching object with a first bleaching liquid that bleaches the dye at a bleaching temperature equal to or higher than the fiber-opening temperature at which the molecular chains of the fibers contained in the bleaching object loosen to an extent that the pigment escapes through gaps in the molecular chains of the fibers; an exhaust device for exhausting fumes of the first bleaching liquid generated from the bleaching section; a fume recovery device for returning the fumes to a liquid and recovering them; and a transport section for transporting the bleaching object to the bleaching section and transporting the bleaching object from the bleaching section after decolorization.

16. The decolorizing apparatus according to claim 15, further comprising a sealed housing that houses the decolorizing section and the conveying section, and the exhaust device is attached to the sealed housing so as to exhaust the fumes from inside the sealed housing to the outside.

17. The decolorizing apparatus according to claim 15, further comprising a hood disposed above an opening through which the fumes exit the decolorizing section and covering the opening, the exhaust device being attached to the hood.

18. The decolorizing device according to claim 15, wherein the decolorizing section includes a first treatment tank for holding the first decolorizing solution, a first storage tank for storing the first decolorizing solution and supplying the first decolorizing solution to the first treatment tank, and a heating device for heating the first decolorizing solution in the first treatment tank or the first storage tank to the decolorizing temperature.

19. The bleaching device according to claim 18, wherein the bleaching unit includes a stimulation device that applies a mechanical stimulation to the object to be bleached.

20. The decolorizing apparatus of claim 19, wherein the stimulation device includes at least one of a stirring device that stirs the object to be decolorized and the first decolorizing solution in the first treatment tank, a shaking device that shakes the first decolorizing solution in the first treatment tank together with the object to be decolorized, an ultrasonic treatment device that ultrasonically treats the first decolorizing solution together with the object to be decolorized in the first treatment tank, and a stirring blade that is positioned so as to come into contact with the object to be decolorized in the first treatment tank.

21. The decolorizing device according to claim 18, wherein the decolorizing section supplies the first decolorizing liquid from the first storage tank to the first treatment tank, and washes the object to be decolorized with the first decolorizing liquid while discharging excess of the first decolorizing liquid from the first treatment tank.

22. The bleaching device according to claim 15, wherein the bleaching section includes a spray device that sprays the first bleaching solution at the bleaching temperature as a liquid or gas onto the object to be bleached.

23. The decolorizing device according to claim 15, wherein the decolorizing section further washes the object to be decolorized that has been decolorized with the first decolorizing solution with a second decolorizing solution having a temperature lower than the fiber-opening temperature and capable of decolorizing the dye.

24. The decolorizing device according to claim 15, further comprising a rinsing section for washing the object to be decolorized which has been decolorized in the decolorizing section with a second decolorizing liquid having a temperature lower than the fiber-opening temperature and capable of decolorizing the dye, and wherein the transport section transports the object to be decolorized after decolorization from the decolorizing section to the rinsing section.

25. The decolorizing device according to claim 15, further comprising an impurity removal device for removing the dye from the used first decolorizing solution discharged from the decolorizing section.

26. The decolorizing apparatus according to any one of claims 15 to 25, further comprising: a deliquification device for deliquifying the object to be decolorized; and a drying device for drying the object to be decolorized.

27. The decolorizing device according to claim 15, which is constructed to be explosion-proof.

28. The color removing device according to claim 15, wherein the fibers include at least one of polyester fibers and nylon fibers.

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