Bleaching Method and Bleaching Device

The present invention relates to a bleaching method and a bleaching apparatus.

From the viewpoint of recent environmental protection, petrochemicals are increasingly required to suppress resource consumption or reduce environmental load. Problems of fiber products, one of the petrochemicals, are known to require a lot of energy for production and cause environmental load such as carbon dioxide emission in the course of production thereof. Hence, ecofriendly approaches have heretofore been sought, such as reduction in waste by the recycling of the fiber products or the development of durable fiber products.

Examples of the approach of reducing environmental load as to fiber products such as clothing include the prolongation of fiber product life. However, the fiber products, when treated for a long period, cause various troubles such as coloring ascribable to deposits, coloring caused by thermal or ultraviolet alteration of fibers, or shrinkage or color fading in laundry.

Among these troubles, dirt ascribable to deposits during wear or handling is known as coloring, which often matters in general households. Typical examples of the causative substance of coloring ascribable to deposits include yellowing originating from sweat or sebum dirt, and stains of colored beverages such as vegetable or fruit juices. Particularly, sweat or sebum dirt is often difficult to completely remove by a usual laundry process or only washing with a detergent. Organic components contained in such dirt accumulate in fibers over time and are further oxidized by oxygen or the like in air, easily causing yellowing.

Other examples of the causative substance of coloring ascribable to deposits include antioxidants. The antioxidants are known to be oxidized by oxygen in air, causing yellowing, as in sweat or sebum dirt.

For example, dibutylhydroxytoluene (BHT) is known as an antioxidant deposited on fiber products, and transferred from packaging materials or hangers in the course of production, distribution, or storage of fiber products. Although BHT itself is white, this substance reacts with nitrogen oxide or the like in the atmosphere to generate a yellow compound 3,3′,5,5′-tetra-tert-butyl-4,4′-stilbenequinone (TBSQ). Since this yellow compound sublimates, products containing BHT are likely to be yellowed even if the products are made of any material.

Antioxidants may be used as additives for imparting a deodorizing effect to fiber products (see, for example, Japanese Patent Laid-Open No. 10-131042). Such fiber products supplemented with the antioxidants may be colored over time.

Washing with bleach cleaning agents for apparel having a bleaching effect is typically known as an approach of solving the coloring of fiber products as mentioned above. Particularly, oxygen-based bleach cleaning agents are mainstream bleach cleaning agents for apparel because of the absence of color fading when applied to fiber products which are colored or patterned apparel.

Nonetheless, the oxygen-based bleach cleaning agents have a problem of not having sufficient bleaching power and therefore disadvantageously find the difficulty in completely removing causative substances of coloring.

In light of such problems, many additives have been studied and disclosed, such as bleaching activators containing organic peroxide, and bleaching activation catalysts using a metal complex as a catalyst in order to improve the bleaching power of oxygen-based bleach cleaning agents (for example, Patent literature 2 to 5).

However, the previously proposed techniques of removing causative substances of coloring mentioned above have a problem of being still insufficient. In response to such problems, a method of performing high-temperature treatment involving bleaching under high-temperature steam, and a method using a chemical such as a stronger chlorine-based bleaching agent (e.g., hypochlorous acid or dichlorocyanuric acid) have been proposed as other approaches of improving bleaching power. However, the former method has problems of enormous necessary energy consumption and large damage on fiber products, while the latter method has problems of environmental load as well as the color of cloth that often fades away.

If fiber products are insufficiently rinsed after use of a strong chemical, there are problems that residual chemical components deposited on the fiber products cause time-dependent change to disadvantageously color the fiber products, or fluorescent brighteners are eliminated by the chemical so that the fiber products disadvantageously seem like having turned yellow.

Accordingly, an object of the present invention is to provide 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 inventors have conducted diligent studies to solve the problems of the conventional techniques mentioned above, and consequently completed the present invention by finding that a colored fiber is irradiated with light having a specific wavelength, whereby a coloring component in the fiber is converted to a non-coloring component.

Specifically, the present invention is as follows.

[1]

A bleaching method comprising the step of

The bleaching method according to [1], wherein

The bleaching method according to [1] or [2], wherein

The bleaching method according to [3], wherein

The bleaching method according to [1] or [2], wherein

The bleaching method according to any one of [1] to [5], wherein

The bleaching method according to any one of [1] to [6], wherein

The bleaching method according to any one of [1] to [6], wherein

The bleaching method according to any one of [1] to [8], wherein

The bleaching method according to any one of [1] to [8], wherein

The bleaching method according to any one of [1] to [10], wherein

The bleaching method according to any one of [1] to [11], wherein

A bleaching apparatus comprising

The bleaching apparatus according to [13], further comprising

The bleaching apparatus according to [13] or [14], wherein

The bleaching apparatus according to any one of [13] to [15], further comprising

The bleaching apparatus according to [16], wherein

The bleaching apparatus according to any one of [13] to [17], wherein

The bleaching apparatus according to any one of [16] to [18], wherein

The bleaching apparatus according to any one of [16] to [18], wherein

The bleaching apparatus according to any one of [16] to [20], further comprising

The present invention can provide 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.

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.

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.

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.

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.

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.).

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.).

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

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

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.

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.

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.

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