Bleaching Method and Bleaching Device

Abstract

Provided are a bleaching method capable of bleaching the color of a fiber product without the use of a high-temperature treatment or a chemical, and a bleaching apparatus for use in the bleaching method. The present invention provides a bleaching method comprising the step of irradiating a colored fiber with light comprising a wavelength of 360 to 600 nm in the presence of oxygen.

Claims

1. A bleaching method comprising the step of irradiating a colored fiber with light comprising a wavelength of 360 to 600 nm in the presence of oxygen.

2. The bleaching method according to claim 1, wherein an output power of the light is 0.001 W/cm.sup.2 or more.

3. The bleaching method according to claim 1, wherein the colored fiber has color ascribable to an external deposit.

4. The bleaching method according to claim 3, wherein the external deposit is at least one member selected from the group consisting of squalene, cholesterol, wax, triglyceride, diglyceride, monoglyceride, fatty acid, protein, mineral, and microbe.

5. The bleaching method according to claim 1, wherein the colored fiber has color ascribable to sun damage and/or thermal degradation.

6. The bleaching method according to claim 1, wherein the colored fiber is an animal hair fiber or a silk fiber.

7. The bleaching method according to claim 1, wherein the light has a wavelength of 360 to 390 nm.

8. The bleaching method according to claim 1, wherein the light has a wavelength of 390 to 480 nm.

9. The bleaching method according to claim 1, wherein the colored fiber is irradiated with the light in a non-contact state with a solvent.

10. The bleaching method according to claim 1, wherein the colored fiber is irradiated with the light in a contact state with water and/or an alcohol.

11. The bleaching method according to claim 1, wherein the colored fiber is irradiated with the light in a cooled state.

12. The bleaching method according to claim 1, wherein the step of irradiation with the light employs a light-emitting diode light source and/or a laser light source.

13. A bleaching apparatus comprising a light irradiation unit that irradiates a colored fiber with light comprising a wavelength of 360 to 600 nm in the presence of oxygen.

14. The bleaching apparatus according to claim 13, further comprising a guard that transmits the light through it between the light irradiation unit and the colored fiber.

15. The bleaching apparatus according to claim 13, wherein the colored fiber is irradiated with the light at an illuminance of 0.001 W/cm.sup.2 or more.

16. The bleaching apparatus according to claim 13, further comprising a cooling unit that cools the colored fiber.

17. The bleaching apparatus according to claim 16, wherein the cooling unit cools the colored fiber to 30 C. or lower.

18. The bleaching apparatus according to claim 13, wherein a placement position of the colored fiber is a position facing the light irradiation unit, and a light-shielding unit is disposed at a position that does not inhibit the light irradiation of the colored fiber from the light irradiation unit.

19. The bleaching apparatus according to claim 16, wherein the cooling unit has a feed water tank and a water spray unit, and the water spray unit sprays water to the colored fiber.

20. The bleaching apparatus according to claim 16, wherein the cooling unit is an air-cooled heat sink and/or a water-cooled heat sink, a hole and/or a groove is disposed in a contact surface of the cooling unit with the colored fiber, and water vapor and/or water is discharged from the hole and/or the groove.

21. The bleaching apparatus according to claim 16, further comprising a temperature detector that detects a temperature of the colored fiber, wherein the temperature detector terminates the light irradiation from the light irradiation unit depending on the detected temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0069] FIG. 1 shows UV-vis spectra of a sample without light irradiation (Before light irradiation) and a sample irradiated with light of 445 nm such that an integrated light intensity was 3.75 W.Math.hr/cm.sup.2 (After light irradiation) as to 3,3,5,5-tetra-tert-butyl-4,4-stilbenequinone (TBSQ) serving as a deposit on a fiber and a coloring component;

[0070] FIG. 2 shows UV-vis spectra of a sample without light irradiation (Before light irradiation) and a sample irradiated with light of 445 nm such that an integrated light intensity was 3.75 W.Math.hr/cm.sup.2 (After light irradiation) as to -carotene serving as a deposit on a fiber and a coloring component;

[0071] FIG. 3 shows UV-vis spectra of a sample without light irradiation (Before light irradiation) and a sample irradiated with light of 445 nm such that an integrated light intensity was 3.75 W.Math.hr/cm.sup.2 (After light irradiation) as to lycopene serving as a deposit on a fiber and a coloring component;

[0072] FIG. 4 shows a graph in which the relationship between an integrated light intensity and a whiteness was plotted when a sample impregnated with an orange-containing beverage (manufactured by Kirin Holdings Co., Ltd., trade name Tropicana 100%) serving as a deposit on a fiber and a coloring component was irradiated with light of 445 nm;

[0073] FIG. 5 shows a schematic cross-sectional view of one example of the bleaching apparatus of the present embodiment;

[0074] FIG. 6 shows a schematic cross-sectional view of another example of the bleaching apparatus of the present embodiment;

[0075] FIG. 7 shows a schematic cross-sectional view of a configuration in which a cooling unit is disposed in the bleaching apparatus of the present embodiment;

[0076] FIG. 8(A) shows a schematic cross-sectional view of one example of a configuration in which a water-cooled heat sink is disposed as a cooling unit in the bleaching apparatus of the present embodiment; FIG. 8(B) shows a schematic top view of a water cooling unit;

[0077] FIG. 9(A) shows a schematic cross-sectional view of one example of a configuration in which an air-cooled heat sink is disposed as a cooling unit in the bleaching apparatus of the present embodiment; FIG. 9(B) shows a schematic top view of an air cooling unit;

[0078] FIG. 10(A) shows a schematic cross-sectional view of another example of a configuration in which an air-cooled heat sink is disposed as a cooling unit in the bleaching apparatus of the present embodiment; FIG. 10(B) shows a schematic top view of an air cooling unit;

[0079] FIG. 11 shows a schematic cross-sectional view of a configuration in which a heating unit is disposed in the bleaching apparatus of the present embodiment;

[0080] FIG. 12 shows a schematic cross-sectional view of a configuration in which a water spray unit is disposed in the bleaching apparatus of the present embodiment;

[0081] FIG. 13 shows a schematic cross-sectional view of an alternative example of the bleaching apparatus of the present embodiment;

[0082] FIG. 14 shows a schematic cross-sectional view of a bleaching apparatus configured to employ an iron in a heating unit;

[0083] FIG. 15 shows a schematic cross-sectional view of a usage form of a bleaching apparatus configured to employ an iron in a heating unit;

[0084] FIG. 16 shows a schematic cross-sectional view of an alternative example of the bleaching apparatus of the present embodiment;

[0085] FIG. 17 shows a schematic cross-sectional view of an alternative example of the bleaching apparatus of the present embodiment;

[0086] FIG. 18 shows a schematic front view of an alternative example of the bleaching apparatus of the present embodiment; and

[0087] FIG. 19 shows a schematic front view of an alternative example of the bleaching apparatus of the present embodiment.

DETAILED DESCRIPTION OF THE INVENTION

[0088] Hereinafter, the mode for carrying out the present invention (hereinafter, referred to as the present embodiment) will be described in detail. However, the present invention is not limited by the description below and can be carried out with various changes or modifications made therein without departing from the spirit of the present invention.

[Bleaching Method]

[0089] The bleaching method of the present embodiment comprises the step of irradiating a colored fiber with light comprising a wavelength of 360 to 600 nm in the presence of oxygen.

[0090] According to the bleaching method of the present embodiment, light acts only on an organic component depending on an irradiation wavelength without the use of high-temperature treatment or a chemical so that color can be bleached without large damage on a fiber.

(Fiber)

[0091] In the bleaching method of the present embodiment, the fiber to be bleached is not particularly limited, and any available fiber can be used. Examples thereof include, but are not limited to, natural fibers, synthetic fibers, semisynthetic fibers, regenerated fibers, and blends of these various fibers. Further, fiber products obtained by processing these fibers, such as fabrics, clothing, bags, and shoes, are also included in the scope of the fiber to be bleached in the bleaching method of the present embodiment.

[0092] Examples of the natural fiber include, but are not limited to, animal fibers such as animal hair fibers (wool, cashmere, etc.) and silk fibers (silk, etc.), and plant fibers such as seed hair fibers (cotton, kapok, etc.), bast fibers (hemp, linen, jute, etc.), and leaf vein fibers (sisal hemp, etc.).

[0093] Examples of the synthetic fiber include, but are not limited to, polyamide fibers (nylon, etc.), polyester fibers (polyester, etc.), polyacrylonitrile fibers (acryl, etc.), polyurethane fibers (polyurethane, etc.), polyvinyl alcohol fibers (vinylon, etc.), polyvinyl chloride fibers (polyvinyl chloride, etc.), polyvinylidene chloride fibers (vinylidene, etc.), and polyolefin fibers (polyethylene, polypropylene, etc.).

[0094] Examples of the semisynthetic fiber include, but are not limited to, cellulose fibers (acetate, etc.) and protein fibers (Promix, etc.).

[0095] Examples of the regenerated fiber include, but are not limited to, cellulose fibers (rayon, polynosic, cupra, etc.).

[0096] Examples of the fiber product include, but are not limited to, products such as dress shirts, T-shirts, polo shirts, blouses, chinos, suits, pants, skirts, tablecloths, place mats, curtains, bedclothes, hats, sofas, toilet mats, handkerchiefs, towels, knits, socks, underwear, tights, and masks.

(Coloring)

[0097] In the bleaching method of the present embodiment, a colored fiber is to be bleached. The colored fiber may have color ascribable to an external deposit or may have color ascribable to fiber alteration due to sun damage and/or thermal degradation, or the like.

<External Deposit>

[0098] Dirt on a fiber ascribable to the external deposit expected as a causative substance of coloring will be described below. However, the bleaching method of the present embodiment is not limited by the description below.

[0099] Coloring ascribable to the external deposit is classified into two groups, dirt from the human body and dirt from the environment.

[0100] Examples of the dirt from the human body include sweat, sebum, skin waste products, resident skin bacteria, blood, human milk, and excrement. Their components or amounts differ largely depending on various factors such as a site in the human body, the number of times of wear, season, or difference among individuals. Examples of the dirt deposited on the collar or underwear include squalene, cholesterol (including ester), wax, triglyceride, diglyceride, monoglyceride, fatty acid (including palmitic acid and oleic acid), protein, mineral, and microbe. Among these components, an organic component such as squalene or oleic acid colors a fiber through sunlight, heat, or air oxidation, though the component itself is colorless.

[0101] Examples of the dirt from the environment include stains originating from the cooking or spillage of food or drink such as animal fats, plant oils, fruit juices, colored beverages, and seasonings, stains originating from body care products such as hand creams, body creams, soaps, moisturizers, sunscreens, and cosmetics, antioxidants originating from packaging materials or hangers, dust in air, and automobile exhaust gases.

[0102] These components tend to be difficult to wash or bleach while increasing coloring, when left for a long period in the presence of oil or protein or when thermally denatured.

[0103] The bleaching method of the present embodiment, because of having the step of irradiation with light comprising a wavelength of 360 nm to 600 nm, has a larger fiber bleaching effect, which is preferred, when color derived from the external deposit mentioned above has absorption in a wavelength region of 360 to 600 nm. Whether the color derived from the external deposit has absorption in a predetermined wavelength region can be confirmed by reflectometry using a spectrocolorimeter mentioned later.

<Coloring Ascribable to Fiber Alteration>

[0104] The bleaching method for coloring of a fiber ascribable to fiber alteration expected as a cause of coloring will be described below. However, the bleaching method of the present embodiment is not limited by the description below.

[0105] Examples of the coloring ascribable to fiber alteration include coloring ascribable to the alteration of a fiber material itself, and coloring caused by the alteration of a fluorescent brightener, an antiseptic, or the like dyeing the fiber.

[0106] Examples of the coloring ascribable to fiber alteration include the case where the fiber is altered and colored due to repeated drying, ironing, or the like (thermal degradation), the case where the fiber is altered and colored due to the influence of ultraviolet ray such as sunlight or a fluorescent lamp (sun damage), and the case where a fluorescent brightener, an antiseptic, or the like is degraded and colored due to the influence of ultraviolet ray (optical degradation).

[0107] The coloring ascribable to fiber alteration mentioned above may occur, irrespective of the type of the fiber. However, particularly, synthetic fibers such as nylon or various natural fibers such as wool, cashmere, other animal hair fibers, and silk tend to be susceptible to heat or ultraviolet ray. The coloring ascribable to fiber alteration tends to be difficult to repair by bleaching. Nonetheless, the bleaching method of the present embodiment can effectively reduce a colored state.

(Fiber Bleaching Method)

[0108] The bleaching method of the present embodiment comprises the step of irradiation with light comprising a wavelength of 360 nm to 600 nm in the presence of oxygen.

[0109] A mechanism under which irradiation with light having a wavelength of 360 to 600 nm produces a bleaching effect is considered as follows: an organic component responsible for the coloring of a fiber is excited by the light irradiation and converted to a non-coloring component through oxidation reaction that progresses between the organic component and oxygen or a part of a fiber component to cause bleaching. When the fiber has no absorption at the irradiation wavelength, the fiber merely reflects light having the irradiation wavelength without being decomposed or degraded and is therefore not damaged.

[0110] In the bleaching method of the present embodiment, the light used to irradiate the fiber comprises light having a wavelength of 360 to 600 nm and preferably, mainly comprises light having a wavelength of 360 to 600 nm.

[0111] The phrase mainly comprise light having a wavelength of 360 to 600 nm means that the spectral output power of the light having a wavelength of 360 to 600 nm in the light used to irradiate the irradiation target is 50% or more of the whole irradiation light.

[0112] More preferably, the light mainly comprises light having a wavelength of 390 to 480 nm, further preferably light having a wavelength of 400 to 460 nm, from the viewpoint of the suppression of fiber degradation and energy intensity.

[0113] More preferably, the light mainly comprises light having a wavelength of 360 to 390 nm, further preferably light having a wavelength of 360 to 370 nm, from the viewpoint of abundant coloring ascribable to an oxidatively decomposable external deposit.

[0114] In the bleaching method of the present embodiment, the light used to irradiate the fiber can be appropriately selected depending on the absorption band of the color of the irradiation target fiber. The light may be light having a single wavelength or may comprise lights having multiple wavelengths. Examples thereof include lights comprising lights having a single wavelength or multiple wavelengths in the range of 360 to 600 nm, and lights having a single wavelength or multiple wavelengths outside the range of 360 to 600 nm.

[0115] The irradiation light may comprise, albeit slightly, light having a wavelength shorter than 360 nm. However, long-time continuous irradiation with light having a short wavelength less than 360 nm, which has a high light output power, might cause decomposition or new coloring of the irradiation target fiber. Therefore, light mainly comprising light having a wavelength of 360 to 600 nm is preferred, and light comprising no wavelength of less than 360 nm is preferred for irradiation. More preferably, only light having a wavelength of 360 to 600 nm is used as a light source. For minimizing decomposition or new coloring of the irradiation target fiber, it is preferred, for example, to select an irradiation light source so as not to comprise light having a wavelength of less than 360 nm, or combine filters that cut off wavelengths other than the wavelength of interest.

[0116] The irradiation light may comprise light having a wavelength longer than 600 nm. A longer wavelength of the light tends to have less influence on the coloring of the irradiation target. However, irradiation with light, particularly, in the infrared region might elevate the temperature of the irradiation target itself and render temperature control difficult for the irradiation target. Therefore, the irradiation light is preferably only light in the visible light region.

[0117] Among organic components responsible for the coloring of a fiber, particularly, a yellow component well absorbs light in a wavelength range of 390 to 480 nm and therefore receives a large bleaching effect when irradiated with light in this wavelength range.

[0118] FIGS. 1 to 3 each show the average gram extinction coefficient in a wavelength range of 400 nm to 500 nm when a predetermined coloring component was irradiated with light having a wavelength of 445 nm.

[0119] Specifically, FIG. 1 shows the average gram extinction coefficient from 400 nm to 500 nm when an antioxidant-derived coloring component 3,3,5,5-tetra-tert-butyl-4,4-stilbenequinone (TBSQ) was irradiated with light of 445 nm; FIG. 2 shows the average gram extinction coefficient from 400 nm to 500 nm when a coloring component -carotene contained in vegetables or fruits was irradiated with light of 445 nm; and FIG. 3 shows the average gram extinction coefficient from 400 nm to 500 nm when lycopene was irradiated with light of 445 nm.

[0120] FIGS. 1 to 3 each show UV-vis spectra of a sample without light irradiation (Before light irradiation) and a sample irradiated with light of 445 nm such that an integrated light intensity was 3.75 W.Math.hr/cm.sup.2 (After light irradiation).

[0121] As shown in FIGS. 1 to 3, the average gram extinction coefficient in the wavelength range was found to be markedly reduced after light irradiation.

[0122] In the bleaching method of the present embodiment, the output power of the light used to irradiate the fiber is in the range of preferably 0.001 W/cm.sup.2 or more, more preferably 0.001 to 10 W/cm.sup.2.

[0123] The output power of the irradiation light is 0.001 W/cm.sup.2 or more, whereby photoreaction progresses sufficiently so that long-time irradiation is not necessary and improvement in hue can be sufficiently achieved.

[0124] The output power is 10 W/cm.sup.2 or less, whereby photoreaction and thermal reaction can prevent the fiber itself from being degraded or a new coloring component from being generated, and can effectively suppress reduction in bleaching effect.

[0125] The output power of the irradiation light is further preferably 0.005 to 5 W/cm.sup.2, still further preferably 0.01 to 3 W/cm.sup.2.

[0126] The output power of the irradiation light preferably satisfies the above numeric range throughout the surface of the fiber. More preferably, a colored region of the fiber is irradiated such that the light output power is uniform.

[0127] The output power of the irradiation light can be measured with an actinometer, a power meter, or the like using a photodiode. Also, the light output power per irradiated area (cm.sup.2) can be measured by measuring a radiant flux (W). A specific output power of the irradiation light can be estimated by placing an actinometer, a power meter, or the like at a location corresponding to the surface of the irradiation target to be irradiated with the light, and measuring a light output power.

[0128] In the light irradiation of the fiber mentioned above, the light output power is preferably constant during irradiation or may be fluctuated. In the case of fluctuating the light output power, the light output power of the irradiation light is preferably controlled so as to satisfy the numeric range mentioned above. The fiber may be irradiated with the irradiation light in a plurality of directions or may be irradiated in one direction. The light source is preferably disposed so as to uniformly irradiate the fiber from the viewpoint of uniform irradiation.

[0129] In the bleaching method of the present embodiment, the integrated light intensity of the irradiation light for the fiber is preferably 0.001 W.Math.hr/cm.sup.2 or more.

[0130] The integrated light intensity is 0.001 W.Math.hr/cm.sup.2 or more, whereby the photoreaction of a coloring component progresses sufficiently and a bleaching effect tends to progress sufficiently.

[0131] The integrated light intensity of the irradiation light for the fiber is more preferably 0.01 W.Math.hr/cm.sup.2 or more, further preferably 0.1 W.Math.hr/cm.sup.2 or more.

[0132] As for the relationship between the integrated light intensity of the irradiation light for the fiber and the degree of bleaching, preferably, the integrated light intensity is properly selected depending on the type or amplitude of coloring, or an intended yellowness index or whiteness after bleaching.

[0133] FIG. 4 shows a graph in which the relationship between an integrated light intensity and a whiteness was plotted when a sample impregnated with an orange-containing beverage (manufactured by Kirin Holdings Co., Ltd., trade name Tropicana 100%) serving as a deposit on a fiber and a coloring component was irradiated with light of 445 nm such that a light output power was 0.36 W/cm.sup.2, and an irradiation time was 0 minutes, 5 minutes, 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 80 minutes, 100 minutes, 120 minutes, 150 minutes, and 180 minutes.

[0134] As shown in FIG. 4, the whiteness was found to be improved with increase in integrated light intensity.

[0135] The integrated light intensity for the fiber can be measured with an integration actinometer, a power meter, or the like using a photodiode. The integrated light intensity is an integral value of a time (hr) of a radiation density (energy density (W/cm.sup.2)). Therefore, provided that a radiant flux (W) can be measured, an energy density can be determined by calculating a radiant flux per irradiated area (cm.sup.2); thus, the integrated light intensity can be determined from an irradiation time.

[0136] In the bleaching method of the present embodiment, the time for which the fiber is irradiated with the light is preferably a short time from the viewpoint of productivity or may be a long time as long as the light irradiation of the irradiation target is performed during storage. The light irradiation may be performed continuously or discontinuously. Continuous irradiation is preferred from the viewpoint of efficiency. In the case of performing discontinuous light irradiation, the integrated light intensity also preferably falls within the numeric range mentioned above.

[0137] In the bleaching method of the present embodiment, the temperature of the irradiation target colored fiber in the light irradiation step is preferably in the range of 0 C. or higher and lower than 220 C., more preferably in the range of 0 C. or higher and lower than 100 C. from the viewpoint of suppressing fiber degradation, further preferably 80 C. or lower from the viewpoint of preventing users from getting a burn, still further preferably 60 C. or lower. Particularly, the temperature of the irradiation target is 100 C. or higher, whereby productivity is improved by accelerating photoreaction. However, such a temperature tends to present problems such as the degradation of the irradiation target fiber resulting in reduction in physical property, or a burnt fiber itself.

[0138] The bleaching method of the present embodiment preferably comprises the step of irradiating the irradiation target colored fiber with the light in a cooled state by contact with a cooling unit, from the viewpoint of preventing the fiber from being degraded by elevation in temperature. The cooling temperature in the cooling unit contacted with the irradiation target is preferably 0 to 50 C.

[0139] In the bleaching method of the present embodiment, the light source for use in the light irradiation can be appropriately selected from artificial light sources.

[0140] Examples of the artificial light source include, but are not limited to, incandescent bulbs, fluorescent lamps, halogen lamps, mercury lamps, metal halide lamps, xenon lamps, light-emitting diodes (LEDs), and laser light sources. Among them, particularly, LED or a laser light source is preferred from the viewpoint of irradiation with only light having a wavelength of 360 to 600 nm, which is highly effective for improvement in hue. These light sources may be used in appropriate combination in consideration of the degradation of the fiber by heating, or the like. Although a natural light such as sunlight may be selected, an artificial light source is more preferred from the viewpoint of efficiency.

[0141] If elevation in temperature by the light irradiation is problematic, the degradation of the fiber by elevation in temperature can be suppressed by installing an infrared cutoff filter or establishing a cooling mechanism by air cooling, water cooling, or the like.

[0142] In the bleaching method of the present embodiment, the light irradiation is performed in the presence of oxygen.

[0143] In this context, the phrase in the presence of oxygen means in an environment containing an oxygen molecule (O.sub.2).

[0144] For example, any atmosphere of air, oxygen gas, water vapor, or a solvent may be used, and air is preferred from the viewpoint of cost and convenience. During the light irradiation, the flow rate of a gas introduced to a light irradiation apparatus may be measured and appropriately adjusted.

[0145] The bleaching method of the present embodiment can bleach the colored fiber by the light irradiation in a non-contact state with a solvent, i.e., in the absence of a solvent. On the other hand, the bleaching method of the present embodiment is not limited by such a mode, and the fiber may be bleached by the light irradiation in a contact state with a predetermined solvent.

[0146] Examples of the solvent include, but are not limited to, water, alcohols, chain or cyclic alkanes, ethers, and petroleum-based solvents. A solvent that transmits the light having the irradiation wavelength through it can be used, and water or an alcohol is particularly preferred.

[0147] The bleaching method of the present embodiment does not require adding a chemical for bleaching. A solvent may be used in bleaching, and the solvent can contain an arbitrary additive. Alternatively, the colored fiber may be coated with a paste of an additive in the absence of a solvent.

[0148] Examples of the additive include, but are not limited to, arbitrary components such as bleaching agents, bleaching activators, enzymes, surfactants, oxidizing agents, reducing agents, fragrances, inorganic builders, anti-re-contamination agents, dispersants, fluorescent coating materials, antioxidants, dyes, antibacterial agents, antiseptics, antifoaming agents, and polymers.

[0149] The bleaching method of the present embodiment may comprise the step of washing the fiber after the light irradiation step. This is preferred because the step can remove a compound resulting from photoreaction or the like from the fiber and, even if an additive is used as mentioned above, can remove the additive from the fiber.

[0150] In the case of performing bleaching or washing using a solvent, a subsequent drying step may be carried out.

[0151] An advantage of the bleaching method of the present embodiment is that the colored fiber can be bleached in the absence of a solvent and the addition of a chemical for bleaching is not necessary. Particularly, when the fiber is any of various animal hair fibers such as wool or cashmere, and natural fibers such as silk, the application of a bleaching method that requires neither a solvent nor a chemical, as in the bleaching method of the present embodiment, is beneficial because the fiber itself is vulnerable to water and not suitable for washing with water and furthermore, is susceptible to degradation by a chemical. Moreover, if an external deposit of the natural fiber is caused by dirt from the human body, the application of the bleaching method of the present embodiment for which a chemical is not essential is very beneficial because the fiber is similar in chemical structure to a dirt component and is easily damaged by use of a chemical for bleaching.

[Bleaching Apparatus]

[0152] The bleaching apparatus of the present embodiment has a light irradiation unit that irradiates a colored fiber with light comprising a wavelength of 360 nm to 600 nm in the presence of oxygen.

[0153] FIG. 5 shows a schematic cross-sectional view of one example of a bleaching apparatus 1 of the present embodiment.

[0154] The bleaching apparatus 1 of the present embodiment has a light irradiation unit 2, and the colored fiber is placed at a position facing the light irradiation unit 2.

[0155] The bleaching apparatus of the present embodiment may be configured such that a light-shielding unit is disposed at a position that does not inhibit the light irradiation of the colored fiber from the light irradiation unit 2. For example, in the bleaching apparatus shown in FIG. 5, the light irradiation unit 2 is provided with a top panel 2a and a plurality of light members 2b disposed on the undersurface side of the top panel 2a, and configured such that a light-shielding unit (shade) 3 is disposed so as to surround the light irradiation unit 2.

[0156] The irradiation light from the light members 2b of the light irradiation unit 2 is preferably an LED and/or laser light having a wavelength of 360 to 600 nm and is preferably set so as to irradiate the colored fiber at an illuminance of 0.001 W/cm.sup.2 or more. The illuminance of the light irradiation unit 2 can be controlled by adjusting an irradiation distance to the fiber to be irradiated, or a light output power.

[0157] The light-shielding unit 3 also functions as legs supporting the top panel 2a of the light irradiation unit 2. The colored fiber to be irradiated is placed in a range contoured by the light-shielding unit 3, and subjected to light irradiation so that the fiber is bleached.

[0158] The light-shielding unit 3 can be formed from, for example, a metal material. The light-shielding unit 3 constituted by the metal material is preferred because the light-shielding unit can prevent the irradiation light from being diffused to the outside, and improve irradiation efficiency. The light-shielding unit 3 may be prepared as a filter constituted by a material that does not transmit only a predetermined irradiation light wavelength through it, and may enable an irradiated state of the colored fiber with the light to be checked.

[0159] A colored part of the fiber is preferably wetted by mist or the like and then subjected to light irradiation, for the purpose of protecting the fiber or promoting bleaching.

[0160] The bleaching apparatus of the present embodiment may have a predetermined control system. Examples of the control system include systems that adjust the range, intensity, and wavelength of the irradiation light depending on the type of the fiber to be bleached, the type of a coloring substance, the range of dirt, and the degree of dirt such as a time elapsed from coloring. The control system enables a user to perform more effective bleaching by selecting, for example, the magnitude of load on the fiber to be bleached, the type of dirt, the degree of dirt, and light irradiation conditions.

[0161] Other examples of the control system include systems that select bleaching conditions from a plurality of preset parameters. Such a system enables the fiber to be bleached into a desired whiteness.

[0162] The bleaching apparatus of the present embodiment may be configured such that the light-shielding unit 3 is attached to the top panel 2a via a hinge 4, as shown in FIG. 6, and have a structure foldable when not in use.

[0163] The bleaching apparatus of the present embodiment may be configured such that a cooling unit 5 is disposed so as to face the light members 2b of the light irradiation unit 2, as shown in FIG. 7.

[0164] In the configuration of the bleaching apparatus shown in FIG. 7, the colored fiber is placed on the cooling unit 5 and irradiated with light comprising a wavelength of 360 nm to 600 nm from the light members 2b of the light irradiation unit 2.

[0165] The cooling mechanism of the cooling unit 5 is not particularly limited as long as the mechanism functions so as not to overheat the fiber during bleaching. Examples thereof include mechanisms of water cooling (small chillers, etc.), air cooling (cooling fans, etc.), evaporative cooling (cooling mechanisms based on heat of vaporization by the spraying of water or the like), spontaneous cooling (heat diffusion using materials having high thermal conductivity), and thermoelectric cooling (cooling through a Peltier effect resulting from the application of current).

[0166] Unlike the removal of heat by heat of vaporization, the cooling unit 5 that exploits cooling using a water-cooled or air-cooled heat sink, as mentioned above, has the advantage that heat can be removed without elevating too much a water vapor concentration around equipment. When the colored fiber to be bleached is wetted in advance before light irradiation or wetted by the spraying of water, heat can be removed by heat of vaporization. However, space separated by the light members 2b and the light-shielding unit 3 is easily filled with water vapor, and condensation easily causes the failure of the light members 2b or the like. Therefore, an approach of removing heat without actively wetting the colored fiber is preferably used.

[0167] The cooling temperature in the cooling unit 5 is not particularly limited as long as the fiber is not overheated during bleaching in this state. For example, a mechanism that allows the cooling unit 5 to have a temperature of 30 C. or lower can perform favorable cooling, and a mechanism that attains a temperature of 20 C. or lower is more preferred. The resulting cooling unit 5 cools the colored fiber to 30 C. or lower and can effectively prevent the degradation of the fiber by the light irradiation.

[0168] FIG. 8(A) shows a schematic cross-sectional view of one example of the cooling unit 5 disposed so as to face the light members 2b of the light irradiation unit 2.

[0169] In FIG. 8(A), the cooling unit 5 has a water-cooled heat sink 5a, a cover 5b, a water inlet 5c, and a water outlet 5d. The cooling temperature is properly controlled by injecting water having a predetermined temperature into the water-cooled heat sink 5a from the water inlet 5c, and discharging water from the water outlet 5d.

[0170] FIG. 8(B) shows a schematic top view of the cover 5b.

[0171] As shown in FIG. 8(B), the cover 5b preferably has a part downgaged into a predetermined size. The downgage means a configuration in which a hole and/or a groove is disposed in a contact surface of the cooling unit 5 with the colored fiber. Water vapor and/or water is thereby discharged from the hole and/or the groove. This can prevent the light irradiation unit 2 from being degraded due to steam generated by vaporization during light irradiation, and can prevent water droplets of the resulting steam from being deposited on the irradiated surface of the light irradiation unit 2. Thus, highly efficient photobleaching can be performed.

[0172] FIG. 9(A) shows a schematic cross-sectional view of another example of the cooling unit 5 disposed so as to face the light members 2b of the light irradiation unit 2.

[0173] In FIG. 9(A), the cooling unit 5 is constituted by air-cooled heat sink 5e. Air having a predetermined temperature can be injected into the air-cooled heat sink 5e and discharged to the outside.

[0174] FIG. 9(B) shows a schematic top view of the air-cooled heat sink 5e.

[0175] As shown in FIG. 9(B), the upper surface part of the air-cooled heat sink 5e preferably has a part downgaged into a predetermined size. This can prevent the light irradiation unit 2 from being degraded due to steam generated by vaporization during light irradiation, and can prevent water droplets of the resulting steam from being deposited on the irradiated surface of the light irradiation unit 2, as in the bleaching apparatus having the configurations of FIGS. 8(A) and 8(B) mentioned above. Thus, highly efficient photobleaching can be performed.

[0176] FIG. 10(A) shows a schematic cross-sectional view of an alternative example of the cooling unit 5 disposed so as to face the light members 2b of the light irradiation unit 2.

[0177] In FIG. 10(A), the cooling unit 5 is constituted by an air-cooled heat sink 5f. Air having a predetermined temperature communicates inside and outside a region contoured by the air-cooled heat sink 5f.

[0178] FIG. 10(B) shows a schematic top view of the air-cooled heat sink 5f.

[0179] As shown in FIG. 10(B), the upper surface part of the air-cooled heat sink 5f preferably has a part downgaged into a predetermined size. This can prevent the light irradiation unit 2 from being degraded due to steam generated by vaporization during light irradiation, and can prevent water droplets of the resulting steam from being deposited on the irradiated surface of the light irradiation unit 2, as in the bleaching apparatus having the configurations of FIGS. 8(A) and 8(B) mentioned above. Thus, highly efficient photobleaching can be performed.

[0180] The bleaching apparatus of the present embodiment may have a configuration provided with a predetermined heating unit.

[0181] FIG. 11 shows a schematic cross-sectional view of a bleaching apparatus configured such that a heating unit 6 is disposed at a position facing the light irradiation unit 2.

[0182] The heating unit 6 heats a colored part of the colored fiber, whereby a bleaching reaction rate tends to be improved so that a bleaching time can be shortened.

[0183] The heating approach of the heating unit 6 is not particularly limited, and a conventionally known one can be used. Examples thereof include configurations provided with electrically heated wire, configurations using steam or warm water, and configurations using induction heating or heating with radiation and/or microwave.

[0184] As shown in FIG. 11, the upper surface of the heating unit 6 preferably has a configuration coated with a reflector 7 having a function of reflecting the light from the light irradiation unit 2. The reflector 7 reflects the light from the light irradiation unit 2, whereby a bleaching effect tends to be improved. The reflector 7 has color that does not absorb the wavelength of the irradiation light from the light irradiation unit 2, whereby heat generation is suppressed and temperature control tends to become easy.

[0185] As shown in FIG. 11, the bleaching apparatus may be configured such that a predetermined guard 8 is disposed between the light members 2b of the light irradiation unit 2 and the fiber. The guard 8 is constituted by a material that transmits the irradiation light through it. The guard 8 thus disposed can suppress the heating of the light irradiation unit 2 by the heat of the heating unit 6 and can protect the light members 2b of the light irradiation unit 2.

[0186] The bleaching apparatus of the present embodiment may be configured such that the predetermined guard 8 is disposed between the light members 2b of the light irradiation unit 2 and the fiber, in any of the case where the configuration is not limited by the presence or absence of the cooling unit 5 or the heating unit 6 as shown in FIGS. 5 and 6, and the case where the cooling unit 5 is disposed as shown in FIGS. 7 to 10. When the cooling unit 5 is disposed as shown in FIGS. 7 to 10, the guard 8 thus disposed can suppress the degradation of the light irradiation unit 2 by condensation resulting from the cooling unit 5, and light scattering ascribable to such condensation, and can protect the light members 2b of the light irradiation unit 2 and retain the illuminance of the light members 2b.

[0187] The bleaching apparatus of the present embodiment may be configured such that, as shown in FIG. 11, a predetermined lock 9 is disposed in lower ends of the light-shielding unit 3, in any of the configuration provided with the cooling unit 5 shown in FIGS. 7 to 10, and the configuration provided with the heating unit 6 as shown in FIG. 11. Examples of the lock 9 include, but are not limited to, magnet locks and rollers. The lock 9 may be disposed in only one end. In such a configuration, the lock 9 may be a hinge.

[0188] The bleaching apparatus of the present embodiment may be configured such that the cooling unit 5 has a predetermined feed water tank and water spray unit.

[0189] FIG. 12 shows a schematic cross-sectional view of one example of the bleaching apparatus having the cooling unit 5 having a water spray unit 10.

[0190] The water spray unit 10 of the cooling unit 5 sprays water to the fiber, whereby heat of vaporization can suppress the overheat of the fiber during bleaching, and a treatment time tends to be able to be shortened by increasing the output power of the irradiation light from the light irradiation unit 2. In a mode preferred for safety management, a timer of the light members 2b is set such that the light members 2b are turned off in a time for the sprayed water to finish evaporating. The guard 8 is disposed between the light members 2b and the water spray unit 10, whereby the light members 2b can be prevented from getting water even if water is sprayed from underneath.

[0191] In the bleaching apparatus having the configuration shown in FIG. 12, the cooling unit 5 may also have a part downgaged into a predetermined size. This can prevent the light irradiation unit 2 from being degraded due to steam generated by vaporization during light irradiation, and can prevent water droplets of the resulting steam from being deposited on the irradiated surface of the light irradiation unit 2, as in the bleaching apparatus having the configurations of FIGS. 8(A) and 8(B) mentioned above. Thus, highly efficient photobleaching can be performed.

[0192] The bleaching apparatus of the present embodiment may be configured to have a temperature detector that detects the temperature of the fiber to be irradiated with the light, from the viewpoint of preventing degradation ascribable to heat accumulation on the fiber to be irradiated with the light.

[0193] The temperature detector has a mechanism that terminates the light irradiation from the light irradiation unit depending on the detected temperature, specifically, when the temperature exceeds a preset temperature.

[0194] The temperature detector is not limited by its placement position as long as the temperature detector can properly measure the temperature of the fiber to be irradiated with the light. The temperature detector can be disposed at an arbitrary location and is preferably disposed at a location that is not exposed directly to the irradiation light.

[0195] As shown in FIG. 13, the bleaching apparatus of the present embodiment may have a vertically reversed configuration of the bleaching apparatus having the configuration shown in FIG. 11. In a possible configuration, only one end of the heating unit 6 may be connected to the light-shielding unit 3 via the lock 9 made of a hinge.

[0196] In the configuration shown in FIG. 13, the colored fiber to be irradiated with the light is disposed between the heating unit 6 and the guard 8.

[0197] As shown in FIG. 13, the bleaching apparatus of the present embodiment may be configured such that the water spray unit 10 is disposed at the upper heating unit 6 of the apparatus. Warm water and/or steam can thereby be sprayed to the fiber.

[0198] The bleaching apparatus of the present embodiment can employ an iron as the heating unit 6.

[0199] FIG. 14 shows a schematic cross-sectional view of a configuration using an iron 11 as the heating unit 6 in the bleaching apparatus of the present embodiment. Any conventionally known iron can be used as the iron 11.

[0200] In the bleaching apparatus having the configuration shown in FIG. 14, a colored fiber 20 to be irradiated with the light is sandwiched between the iron 11 serving as the heating unit and the light irradiation unit 2, as shown in FIG. 15, and can be bleached by light irradiation while heated. In a preferred mode, the colored fiber 20 is placed such that a colored part 20a of the colored fiber 20 faces the light members 2b of the light irradiation unit 2.

[0201] As shown in FIG. 16, the bleaching apparatus of the present embodiment may be configured such that reflectors 7 are disposed on the inner side of the light-shielding unit 3 and the upper end part of the light irradiation unit 2 so as to surround a group of the light members 2b and the guard 8 is disposed so as to cover the undersurfaces and sides of the light members 2b of the light irradiation unit.

[0202] The bleaching apparatus having the configuration shown in FIG. 16 may be configured such that, as shown in FIG. 17, cooling units 5 and water spray units 10 are disposed in both ends of the light irradiation unit.

[0203] FIG. 18 shows a schematic front view of the bleaching apparatus having the configuration shown in FIG. 17.

[0204] In the bleaching apparatus having the configurations shown in FIGS. 17 and 18, the water spray units 10 of the cooling units 5 are not in direct contact with the colored fiber and can spray water to a wide range. The cooling units 5 are arranged with the light members 2b of the light irradiation unit 2, whereby the heat generation of the light members 2b can be effectively suppressed upon use.

[0205] As shown in FIG. 19, the bleaching apparatus of the present embodiment may be configured such that the bleaching apparatus having the configuration shown in FIGS. 16 and 17 may be integrated as a member of an iron.

[0206] In the case of such a configuration, the bleaching apparatus of the present embodiment preferably has a structure where the feed water tank of the iron is used in combination with the feed water tanks of the cooling units 5. A mechanism that does not turn on heating by the iron and light irradiation at the same time is preferred from the viewpoint of safety.

EXAMPLES

[0207] Hereinafter, the present embodiment will be specifically described with reference to specific Examples and Comparative Examples. However, the present invention is not limited by Examples and Comparative Examples given below by any means.

[0208] Physical property measurement methods and evaluation methods in Examples and Comparative Examples are as follows.

[Measurement Method and Evaluation Method]

(1. Evaluation of Yellowness Index and Whiteness of Sample Fabric Before and After Bleaching)

[0209] A sample fabric before and after bleaching obtained in each of Examples and Comparative Examples mentioned later was used in hue measurement using a spectrocolorimeter SD5000 manufactured by Nippon Denshoku Industries, Co., Ltd.

[0210] Specifically, the sample fabric before and after bleaching having a size of 5 cm5 cm was placed in the spectrocolorimeter, and its reflected hue YI (yellowness index) and WL (whiteness) were determined by reflectometry.

[0211] The reflected hue YI (yellowness index) was determined in accordance with JIS K7105 according to the expression YI=100 (1.28X1.06Z)/Y from tristimulus values X, Y, and Z obtained by measurement.

[0212] The WL (whiteness) was determined in accordance with JIS L1916 according to the expression WL=L*+3a*3b* from tristimulus values L*, a*, and b* obtained by measurement.

(2. Determination of Bleaching Effect)

[0213] The rate of decrease in yellowness index of the sample fabric between before and after bleaching was calculated according to the following expression, and a sample having a 30% or more rate of decrease was evaluated as A; a sample having a 20% or more and less than 30% rate of decrease was evaluated as B; a sample having a 10% or more and less than 20% rate of decrease was evaluated as C; and a sample having a less than 10% rate of decrease was evaluated as D.

[00001]$\mathrm{Rate}\mathrm{of}\mathrm{decrease}\mathrm{in}\mathrm{yellowness}\mathrm{index}\left[\%\right]=\left(\mathrm{YI}\mathrm{before}\mathrm{bleaching}\mathrm{or}\mathrm{washing}-\mathrm{YI}\mathrm{after}\mathrm{bleaching}\mathrm{or}\mathrm{washing}\right)/\mathrm{YI}\mathrm{before}\mathrm{bleaching}\mathrm{or}\mathrm{washing}$

[Light Irradiation Apparatus]

[0214] A plurality of NCSC119BT-V1 (peak emission wavelength: 445 nm) LED chips manufactured by NICHIA Corp. were mounted as blue LED to a substrate to prepare a light source for a light irradiation apparatus. A water-cooled heat sink for the suppression of heat generation on the light source side and the irradiated surface side was attached to the light irradiation apparatus, and a chiller was connected thereto to confer a cooling mechanism. A constant-current power supply IT6533D manufactured by ITECH was used as a LED driving power supply.

[0215] The light irradiation apparatus prepared so as to have the configuration described above had a light output power of approximately 1.25 W/cm.sup.2 at a site of 10 mm as a distance from the light source at an applied current of 20 A. A jack was installed in the apparatus such that the distance from the light source was changed by height adjustment. In order to prevent direct or indirect entrance of irradiation light into the human eyes, the apparatus was enclosed in a housing so as not to leak the light to the outside.

[0216] The light irradiation apparatus was lined with a colored sample fabric obtained in each of Examples and Comparative Examples mentioned later. Light irradiation was performed using the light irradiation apparatus under an output power condition involving an applied current of 1 A or 20 A to obtain a light-irradiated sample. The distance from the light source to the irradiation target was set to 10 mm. The temperature of the irradiation target was approximately 30 C. during the light irradiation.

Example 1-1

[0217] A 5 cm5 cm test fabric CN-11 made of cotton without the use of a fluorescent brightener (manufactured by CFT) was used as a standard fabric. The standard fabric was coated with 0.5 mL of a toluene solution containing 10% by mass of squalene as a coloring component to prepare a dirt component-deposited fabric.

[0218] The dirt component-deposited fabric was dried for 10 minutes by air drying and then heated at 90 C. for 120 hours to prepare a colored sample fabric.

[0219] The colored sample fabric had a yellowness index of 27.3 and a whiteness of 34.5%.

[0220] The colored sample fabric was subjected to light irradiation using the light irradiation apparatus such that a light output power was 1.25 W/cm.sup.2, an irradiation time was 10 minutes (integrated light intensity: 0.2 W.Math.hr/cm.sup.2), and a temperature on the irradiated surface side was 20 C. while the temperature was adjusted by cooling using a water-cooled heat sink to obtain a photobleached sample fabric.

[0221] The obtained photobleached sample fabric had a yellowness index of 16.7, a whiteness of 64.8%, and a 39% rate of decrease in yellowness index.

Example 1-2

[0222] A colored sample fabric obtained by the same method as in [Example 1-1] described above was dipped in water and thereby rendered wet to prepare a colored sample fabric of Example 1-2.

[0223] Light irradiation and photobleaching were conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 1-3

[0224] A colored sample fabric was obtained by the same method as in [Example 1-2] described above.

[0225] The colored sample fabric was placed on a glass plate and subjected to light irradiation without cooling using the light irradiation apparatus such that a light output power was 1.25 W/cm.sup.2, and an irradiation time was 10 minutes (integrated light intensity: 0.2 W.Math.hr/cm.sup.2) to obtain a photobleached sample fabric.

Example 1-4

[0226] A colored sample fabric was obtained by the same method as in [Example 1-1] described above.

[0227] The colored sample fabric was subjected to light irradiation using the light irradiation apparatus such that a light output power was 0.16 W/cm.sup.2, an irradiation time was 75 minutes (integrated light intensity: 0.2 W.Math.hr/cm.sup.2), and a temperature on the irradiated surface side was 20 C. while the temperature was adjusted by cooling using a water-cooled heat sink.

[0228] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 1-5

[0229] A colored sample fabric was obtained by the same method as in [Example 1-1] described above.

[0230] The colored sample fabric was subjected to light irradiation using the light irradiation apparatus under a condition of an oxygen concentration decreased to 1% or less by nitrogen flow at a flow rate of 4.0 L/min. Specifically, the colored sample fabric was subjected to light irradiation such that a light output power was 1.25 W/cm.sup.2, an irradiation time was 10 minutes (integrated light intensity: 0.2 W.Math.hr/cm.sup.2), and a temperature on the irradiated surface side was 20 C. while the temperature was adjusted by cooling using a water-cooled heat sink to obtain a photobleached sample fabric.

Example 1-6

[0231] A colored sample fabric was obtained by the same method as in [Example 1-1] described above.

[0232] The colored sample fabric was subjected to light irradiation under spontaneous cooling on an aluminum alloy heat dissipation plate using a LED lamp (PR160L-390 manufactured by Kessil, peak emission wavelength: 390 nm) such that a light output power was 0.80 W/cm.sup.2, and an irradiation time was 15 minutes (integrated light intensity: 0.2 W.Math.hr/cm.sup.2).

[0233] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 1-7

[0234] A colored sample fabric was obtained by the same method as in [Example 1-1] described above.

[0235] The colored sample fabric was subjected to light irradiation under spontaneous cooling on an aluminum alloy heat dissipation plate using a LED lamp (PR160L-370 manufactured by Kessil, peak emission wavelength: 370 nm) such that a light output power was 0.40 W/cm.sup.2, and an irradiation time was 30 minutes (integrated light intensity: 0.2 W.Math.hr/cm.sup.2).

[0236] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 1-8

[0237] The standard fabric used was a test fabric made of nylon (manufactured by MFO).

[0238] By the method in which the other conditions were the same as in [Example 1-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 1-9

[0239] The standard fabric used was a test fabric made of polyester (which abided by JIS L0803, Japanese Standards Association).

[0240] By the method in which the other conditions were the same as in [Example 1-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 1-10

[0241] The standard fabric used was a test fabric made of silk (which abided by JIS L0803, Japanese Standards Association).

[0242] By the method in which the other conditions were the same as in [Example 1-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 1-11

[0243] The standard fabric used was a test fabric made of wool (which abided by JIS L0803, Japanese Standards Association).

[0244] By the method in which the other conditions were the same as in [Example 1-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 1-12

[0245] A colored sample fabric was obtained by the same method as in [Example 1-11] described above.

[0246] The colored sample fabric was subjected to light irradiation by the same method as in [Example 1-3] described above to obtain a photobleached sample fabric.

Example 2

[0247] The coloring component used was a toluene solution containing 10% by mass of oleic acid.

[0248] By the method in which the other conditions were the same as in [Example 1-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 3

[0249] A dirt component-deposited fabric was obtained using a toluene solution containing 10% by mass of dibutylhydroxytoluene (BHT) as a coloring component.

[0250] The dirt component-deposited fabric was subjected to light irradiation using Eye Super UV Tester (SUV-W161 manufactured by Iwasaki Electric Co., Ltd.) such that a light output power was 150 mW/m.sup.2 (300 to 400 nm), and an irradiation time was 300 minutes to obtain s colored sample fabric ascribable to a discolored dirt component.

[0251] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 4-1

[0252] A 5 cm5 cm test fabric CN-11 made of cotton without the use of a fluorescent brightener (manufactured by CFT) was dipped in an orange-containing beverage (manufactured by Kirin Holdings Co., Ltd., trade name Tropicana 100%; hereinafter, referred to as colored beverage 1) for 30 minutes and then rinsed with running water for 10 seconds to prepare a dirt component-deposited fabric. This dirt component-deposited fabric was dried overnight by air drying to prepare a colored sample fabric.

[0253] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 4-2

[0254] A colored sample fabric was obtained by the same method as in [Example 4-1] described above.

[0255] The colored sample fabric was subjected to light irradiation using the light irradiation apparatus under a condition of an oxygen concentration decreased to 1% or less by nitrogen flow at a flow rate of 4.0 L/min. Specifically, the colored sample fabric was subjected to light irradiation such that a light output power was 1.25 W/cm.sup.2, an irradiation time was 10 minutes (integrated light intensity: 0.2 W.Math.hr/cm.sup.2), and a temperature on the irradiated surface side was 20 C. while the temperature was adjusted by cooling using a water-cooled heat sink to obtain a photobleached sample fabric.

Example 5

[0256] The coloring component used was a tomato-containing beverage (manufactured by KAGOME Co., Ltd., trade name KAGOME Tomato Juice; hereinafter, referred to as colored beverage 2).

[0257] By the method in which the other conditions were the same as in [Example 4-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 6

[0258] The coloring component used was black tea (prepared by steeping Nittoh Kocha tea bag manufactured by Mitsui Norin Co., Ltd. as instructed by the package; hereinafter, referred to as colored beverage 3).

[0259] By the method in which the other conditions were the same as in [Example 4-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 7

[0260] The coloring component used was coffee (prepared by making instant coffee manufactured by Doutor Coffee Co., Ltd. as instructed by the package; hereinafter, referred to as colored beverage 4).

[0261] By the method in which the other conditions were the same as in [Example 4-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 81

[0262] The coloring component used was warm water containing 1% by mass of ketchup (manufactured by KAGOME Co., Ltd., trade name KAGOME Tomato Ketchup; hereinafter, referred to as seasoning 1).

[0263] By the method in which the other conditions were the same as in [Example 4-1] described above, a colored sample fabric was obtained and photobleaching was conducted to obtain a photobleached sample fabric.

Example 9

[0264] The colored sample fabric used was a cut piece having a size of 3 cm5 cm taken from the collar of a cotton dress shirt (manufactured by UNIQLO Co., Ltd.) worn for 1 year by an adult male (hereinafter, referred to as shirt dirt 1).

[0265] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 10

[0266] The colored sample fabric used was obtained by subjecting a cut piece having a size of 3 cm5 cm taken from the collar of a cotton dress shirt (manufactured by UNIQLO Co., Ltd.) worn for 1 year by an adult male to ironing 10 times at an iron temperature set to high (hereinafter, referred to as shirt dirt 2).

[0267] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 11

[0268] A test fabric made of nylon (manufactured by MFO) was used as a standard fabric. The standard fabric was subjected to light irradiation using Eye Super UV Tester (SUV-W161 manufactured by Iwasaki Electric Co., Ltd.) such that a light output power was 150 mW/m.sup.2 (300 to 400 nm), and an irradiation time was 300 minutes (hereinafter, referred to as optical degradation condition 1) to obtain s colored sample fabric.

[0269] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 12

[0270] A test fabric made of silk (which abided by JIS L0803, Japanese Standards Association) was used as a standard fabric.

[0271] The other conditions involved the same procedures as in [Example 11] described above to obtain a colored sample fabric. The colored sample fabric was subjected to light irradiation such that a light output power was 1.25 W/cm.sup.2, an irradiation time was 60 minutes (integrated light intensity: 1.3 W.Math.hr/cm.sup.2), and a temperature on the irradiated surface side was 20 C. while the temperature was adjusted by cooling using a water-cooled heat sink to obtain a photobleached sample fabric.

Example 13

[0272] A test fabric made of nylon (manufactured by MFO) was used as a standard fabric. The standard fabric was heated at 90 C. for 150 hours (hereinafter, referred to as thermal degradation condition 1) to obtain a colored sample fabric.

[0273] Photobleaching was conducted by the method in which the other conditions were the same as in [Example 1-1] described above to obtain a photobleached sample fabric.

Example 14

[0274] A test fabric made of silk (which abided by JIS L0803, Japanese Standards Association) was used as a standard fabric.

[0275] The other conditions involved the same procedures as in [Example 13] described above to obtain a colored sample fabric. The colored sample fabric was subjected to light irradiation such that a light output power was 1.25 W/cm.sup.2, an irradiation time was 60 minutes (integrated light intensity: 1.3 W.Math.hr/cm.sup.2), and a temperature on the irradiated surface side was 20 C. while the temperature was adjusted by cooling using a water-cooled heat sink to obtain a photobleached sample fabric.

Comparative Example 1-1

[0276] A colored sample fabric was obtained by the same method as in [Example 1-1] described above.

[0277] The colored sample fabric was washed with water using a washing machine (manufactured by Toshiba Corp., trade name ZABOON) without the use of a detergent in the standard course involving washing for 12 minutes, rinsing three times, dehydration for 6 minutes, and an amount of water used of approximately 90 L, and a total laundry time of 39 minutes (hereinafter, referred to as condition 1).

Comparative Example 1-2

[0278] A colored sample fabric was obtained by the same method as in [Example 1-6] described above.

[0279] The colored sample fabric was washed with water using a washing machine (manufactured by Toshiba Corp., trade name ZABOON) without the use of a detergent under condition 1 described above.

Comparative Example 2

[0280] A colored sample fabric was obtained by the same method as in [Example 2] described above.

[0281] The colored sample fabric was washed by the same method as in [Comparative Example 1-1] described above.

Comparative Example 3

[0282] A colored sample fabric was obtained by the same method as in [Example 3] described above.

[0283] The colored sample fabric was washed by the same method as in [Comparative Example 1-1] described above.

Comparative Example 4

[0284] A colored sample fabric was obtained by the same method as in [Example 4-1] described above.

[0285] The colored sample fabric was washed by the same method as in [Comparative Example 1-1] described above.

Comparative Example 5

[0286] A colored sample fabric was obtained by the same method as in [Example 5] described above.

[0287] The colored sample fabric was washed by the same method as in [Comparative Example 1-1] described above.

Comparative Example 6

[0288] A colored sample fabric was obtained by the same method as in [Example 6] described above.

[0289] The colored sample fabric was washed by the same method as in [Comparative Example 1-1] described above.

Comparative Example 7

[0290] A colored sample fabric was obtained by the same method as in [Example 7] described above.

[0291] The colored sample fabric was washed by the same method as in [Comparative Example 1-1] described above.

Comparative Example 8

[0292] A colored sample fabric was obtained by the same method as in [Example 8] described above.

[0293] The colored sample fabric was washed by the same method as in [Comparative Example 1-1] described above.

TABLE-US-00001 TABLE 1 Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- Exam- ple ple ple ple ple ple ple ple ple ple ple ple ple 1-1 1-2 1-3 1-4 1-5 1-6 1-7 1-8 1-9 1-10 1-11 1-12 2 Standard fabric Cotton Cotton Cotton Cotton Cotton Cotton Cotton Nylon Poly- Silk Wool Wool Cotton ester Type of dirt component Squa- Squa- Squa- Squa- Squa- Squa- Squa- Squa- Squa- Squa- Squa- Squa- Oleic lene lene lene lene lene lene lene lene lene lene lene lene acid Appearance Yellow- 27.3 27.1 27.1 27.8 27.4 27.3 27.1 5.4 20.9 14.8 23.3 22.8 12.1 of fabric ness index Whiteness 34.5 36.0 36.0 33.4 34.8 35.7 35.5 81.8 58.5 62.6 45.8 47.2 74.2 (%) Photo- Irradiation 445 445 445 445 445 390 370 445 445 445 445 445 445 bleaching wave- conditions length (nm) Irradiation 10 10 10 75 10 15 30 10 10 10 10 10 10 time (min) Illumi- 1.25 1.25 1.25 0.16 1.25 0.80 0.40 1.25 1.25 1.25 1.25 1.25 1.25 nance (W/cm2) Appearance Yellow- 16.7 10.9 20.7 16.5 19.7 19.8 20.4 0.4 10.9 10.3 14.0 19.5 4.3 of fabric ness index after Whiteness 64.8 76.5 58.1 62.7 59.7 62.8 60.8 94.6 76.5 77.9 70.5 59.3 90.0 bleaching (%) Determination of A A B A B B B A A A A C A bleaching effect

TABLE-US-00002 TABLE 2 Example Example Example Example Example Example Example 3 4-1 4-2 5 6 7 8 Standard fabric Cotton Cotton Cotton Cotton Cotton Cotton Cotton Type of dirt component BHT Colored Colored Colored Colored Colored Seasoning 1 beverage 1 beverage 1 beverage 2 beverage 3 beverage 4 Appearance of Yellowness 21.1 24.7 24.8 23.3 26.8 24 9.5 fabric index Whiteness (%) 54.5 43.3 45.0 72.3 54.6 54.2 79.4 Photobleaching Irradiation 445 445 445 445 445 445 445 conditions wavelength (nm) Irradiation time 10 10 10 10 10 10 10 (min) Illuminance 1.25 1.25 1.25 1.25 1.25 1.25 1.25 (W/cm2) Appearance of Yellowness 14.2 6.1 17.8 8.2 21.0 13.0 4.9 fabric after index bleaching Whiteness (%) 71.2 84.7 62.9 91.9 64.0 75.4 88.3 Determination of bleaching A A B A B A A effect Example Example Example Example Example Example 9 10 11 12 13 14 Standard fabric Cotton Cotton Nylon Silk Nylon Silk Type of dirt component Shirt Shirt Optical Optical Thermal Thermal dirt 1 dirt 2 degradation degradation degradation degradation condition 1 condition 1 condition 1 condition 1 Appearance of Yellowness 5.0 6.3 5.3 8.6 8.2 2.9 fabric index Whiteness (%) 84.8 85.4 82.7 79.9 78.6 90.9 Photobleaching Irradiation 445 445 445 445 445 445 conditions wavelength (nm) Irradiation time 10 10 10 60 10 60 (min) Illuminance 1.25 1.25 1.25 1.25 1.25 1.25 (W/cm2) Appearance of Yellowness 0.4 0.1 3.5 4.7 3.2 1.3 fabric after index bleaching Whiteness (%) 97.8 100.0 86.8 88.7 91.0 95.5 Determination of bleaching A A A A A A effect

TABLE-US-00003 TABLE 3 Compar- Compar- Compar- Compar- Compar- Compar- Compar- Compar- Compar- ative ative ative ative ative ative ative ative ative Example 1-1 Example 1-2 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 Example 8 Standard fabric Cotton Nylon Cotton Cotton Cotton Cotton Cotton Cotton Cotton Type of dirt component Squalene Squalene Oleic acid BHT Colored Colored Colored Colored Seasoning 1 beverage 1 beverage 2 beverage 3 beverage 4 Appearance Yellowness 27.1 4.8 12.1 21.1 24.7 23.3 26.8 24 9.5 of fabric index Whiteness (%) 35.4 82.5 74.2 54.5 43.3 72.3 54.6 54.2 79.4 Washing condition Condi- Condi- Condi- Condi- Condi- Condi- Condi- Condi- Condi- tion 1 tion 1 tion 1 tion 1 tion 1 tion 1 tion 1 tion 1 tion 1 Appearance Yellowness 22.8 4.7 10.9 20.5 21.9 18.5 23.4 16.8 7.6 of fabric index after washing Whiteness (%) 56.2 82.9 72.0 56.2 50.1 75.2 59.5 67.8 82.5 Determination of bleaching C D D D C B C B B effect

[0294] The bleaching method and the bleaching apparatus of the present invention have industrial applicability for purposes of various services such as cleaning services, coin laundry services, work clothes cleaning services, and subscription services, or services related to, for example, commercial business, such as linen supply services, required at locations such as factories, hotels, hospitals, restaurants, airports, cruise ships, port facilities, public laundries, casinos, apparel shops, and rental shops.

[0295] The bleaching method and the bleaching apparatus of the present invention also have industrial applicability for home use as a bleaching method as a part of existing apparatuses such as washing machines, drying machines, ultrasonic washers, garment steamers, trouser presses, steam irons, rinser cleaners, optical beauty devices, dryers, hair irons, deodorizing hangers, or dental pen-shaped irradiators, or an apparatus dedicated to photobleaching.

REFERENCE SIGNS LIST

[0296] 1: Bleaching apparatus [0297] 2: Light irradiation unit [0298] 2a: Top panel [0299] 2b: Light member [0300] 3: Light-shielding unit [0301] 4: Hinge [0302] 5: Cooling unit [0303] 5a: Water-cooled heat sink [0304] 5b: Cover [0305] 5c: Water inlet [0306] 5d: Water outlet [0307] 5e: Air-cooled heat sink [0308] 5f: Air-cooled heat sink [0309] 6: Heating unit [0310] 7: Reflector [0311] 8: Guard [0312] 9: Lock [0313] 10: Water spray unit [0314] 11: Iron [0315] 20: Fiber [0316] 20a: Colored part of fiber