WO2017131140A1

WO2017131140A1 - Method for producing reptile leather or leather product using hexavalent chromium treatment agent, and reptile leather or leather product using hexavalent chromium treatment agent

Info

Publication number: WO2017131140A1
Application number: PCT/JP2017/002891
Authority: WO
Inventors: 祐司赤尾
Original assignee: シチズン時計株式会社
Priority date: 2016-01-29
Filing date: 2017-01-27
Publication date: 2017-08-03
Also published as: CN108463563A; JP6573993B2; JPWO2017131140A1; EP3409795A4; EP3409795A1; ES2787928T3; CN108463563B; EP3409795B1

Abstract

[Problem] To provide a method for producing reptile leather in which leather can be treated using a hexavalent chromium treatment agent in the process for producing leather, without changing the appearance of the leather. [Solution] The method for producing reptile leather of the present invention includes a chromium tanning step in which chromium tanning is performed on the skin of a reptile to obtain leather, a dyeing/fatliquoring step in which chromium-tanned leather is simultaneously subjected to dyeing and fatliquoring, and a finishing step in which the dyed and fatliquored leather is finished. This method for producing reptile leather further includes a hexavalent chromium treatment step in which leather that has been subjected to chromium tanning in the chromium tanning step has a hexavalent chromium reducing compound, that reduces hexavalent chromium to trivalent chromium, adhered to the tanned leather before the leather is supplied to the finishing step.

Description

Method for producing reptile leather or leather product using hexavalent chromium processing agent and reptile leather or leather product using hexavalent chromium processing agent

The present invention relates to a process for producing reptile leather or leather products using a hexavalent chromium treatment and to reptile leather or leather products using a hexavalent chromium treatment.

Leather products are used in a variety of products such as watch bands and handbags. Especially for watch bands and handbags, the appearance of leather enhances the commercial value and consumer satisfaction. Further, it is needless to say that, in such products, leather has a structure in which the skin is in direct contact with the skin, and the touch of the leather in contact with the skin further enhances the added value of the product.

To produce such leather products, it is necessary to first produce a large sheet of leather. To make leather, get the skin of an animal you want to use for leather products such as crocodile or cow. Since it is inferior to durability and can not be used as it is, tanning treatment is applied to this. This treatment imparts heat resistance and durability, and leather is produced from the leather. The leather thus obtained is colored in a desired color or shaped into a surface to obtain a leather sheet. In order to make it into a leather product using this, it is cut into a shape to be used and processed by sticking to a core material or the like using an adhesive. The production of such leather products is generally and widely known in the old practice.

Tanning is a method of processing leather to obtain durable leather, and there was also a time when tannins collected from plants were used, but this treatment is insufficient in heat resistance, flexibility and elasticity. . For this reason, in recent years, chromium tanning, which has high heat resistance, flexibility, and elasticity using a chromium tanning agent (basic chromium sulfate), has become mainstream. Chromium tanning has a global proportion of over 90% and is of greatest economic importance. By embedding the hydrated chromium complex between the glutamic acid and aspartic acid carboxyl groups of the collagen peptide backbone, a durable and soft leather is obtained. The method of chrome tanning is well known and widely known, and is described, for example, in Non-Patent Document 1.

High-quality leather or leather products excellent in heat resistance, flexibility and elasticity are generally obtained by performing chrome tanning. The chromium tanning agent for chromium tanning contains chromium, which results in a large amount of chromium remaining in the leather or leather product which has been tanned.

Chromium, a chromium tanning agent, is trivalent but may be oxidized to hexavalent by heating or adhesion in the manufacturing process of leather or leather products. Moreover, hexavalent chromium mixed as an impurity in a chromium tanning agent may be mixed in leather or leather products. In addition to hexavalent chromium contained in the production process of leather or leather products, trivalent chromium in leather or leather products is also generated by being oxidized by, for example, light, heat, high temperature humidity, etc. . The presence of hexavalent chromium can be confirmed by a measurement test. Trivalent chromium is harmless, but hexavalent chromium is harmful. When it comes in contact with the skin or mucous membrane, it may cause rough skin or allergy, and when it is severe, it may cause dermatitis or a tumor. Thus, the impact on the human body is large. In addition, even if the amount of hexavalent chromium is small, it is considered to have all harmful risks of carcinogenicity, mutagenicity and reproductive toxicity, and because of its toxicity, it is also treated as a prohibited substance.

Therefore, the EU regulation of hexavalent chromium in leather or leather products was published on March 26, 2014 in the European Union Official Gazette as Regulation (EU) No. 3014/2014 (Regulations (EU), No 3014/2014). According to the Regulations, from May 1, 2015, leather products and products that include leather in the part that comes in contact with the skin, considering the effects on the human body (especially irritation to the skin), consider leather and leather parts Leather products containing 3 mg / kg (3 ppm) or more of chromium (VI) oxide in the total dry weight were to be regulated. In addition, in the Regulations, the EN ISO 17075 standard method is described as the only internationally available analysis method currently available as a method for determining hexavalent chromium in leather or leather products ((6) of Regulations).

On the other hand, Example 2 of Patent Document 1 describes that an aqueous solution of ascorbic acid is dropped onto a tanned leather to render harmless hexavalent chromium contained in the leather.

JP 2008-231388 A

By the way, when a leather, particularly a reptile leather, is treated with a hexavalent chromium treating agent containing a hexavalent chromium reducing compound such as ascorbic acid, the appearance of the leather may change.
Therefore, an object of the present invention is to provide a method for producing a reptile leather, which can be treated with a hexavalent chromium treatment without changing the appearance in the process of producing leather.

The process for producing reptile leather according to the present invention comprises a chromium tanning process for obtaining a leather by performing chrome tanning on reptile skin, and a dyeing and fatifying process for simultaneously dyeing and fatifying a chromium tanned leather, and A finishing process comprising the steps of: finishing the dyed and fatlied leather; and, prior to subjecting the chrome-tanned leather in the chrome-tanning process to the finishing process, 6 A hexavalent chromium treatment step of depositing a hexavalent chromium reducing compound capable of reducing divalent chromium to trivalent chromium.

According to the method for producing reptile leather of the present invention, it is possible to treat leather with a hexavalent chromium treatment agent in the process of producing leather without changing the appearance.

<Manufacturing method of leather>
<Preferred Embodiment [1]>
First, a preferred embodiment of the present invention will be described.

Preferred embodiments of the present invention include a chrome tanning step, a dyeing fatliquoring step and a finishing step. Furthermore, the present embodiment includes a hexavalent chromium treatment process for attaching a hexavalent chromium reducing compound capable of reducing hexavalent chromium to trivalent chromium to the chromium-tanned leather in the chromium-tanning process, The fatliquoring step and the hexavalent chromium treatment step are performed simultaneously.

The chrome tanning step is a step of chrome tanning the reptile skin to obtain leather. In this process, as skins used, sea turtles belonging to the turtle-and-sea turtle family, giant lizards belonging to the lizard sub-family lizard family, degoo belonging to the lizard sub-family Tyididae, snakes belonging to the snake sub-order Boid family, snakes and snakes The skins of reptiles such as sea snakes belonging to the eye sea urchin family, sea snakes, water snakes belonging to the snake subfamily snake, new nig crocodile belonging to the crocodile family crocodile, Mississippi crocodile belonging to the crocodile alligator family, caiman and the like can be mentioned. Chromium tanning can also be carried out by conventional methods.

In the dyeing fatliquoring process, dyeing and fatliquoring are simultaneously carried out on the chrome-tanned leather. This process imparts coloration and flexibility to the leather by the coloring material. There is an advantage that the number of processes can be reduced by performing simultaneously. The embodiment further includes a hexavalent chromium treatment step of depositing a hexavalent chromium reducing compound on the leather. Here, hexavalent chromium that can be contained in leather after chrome tanning is trivalent chromium. Since this hexavalent chromium treatment step is performed simultaneously with the dyeing and fatting step, there is an advantage that the number of treatments can be further reduced.

In the finishing process, finishing is performed on the dyed and fatlied leather. For example, the matt coloration obtained in the fat and oil step is changed to a glossy coloration, or the reptile characteristic stereotype called "ふ (腑, mark or spot)" is produced.

Specifically, polishing the silver surface of leather using agate or glass to make it glossy (glazing), pressing a heated metal roller against the leather to make it glossy, or a heated felt roller In the process, the leather is rubbed to make it glossy. Then, if necessary, the back side of the silver surface is shaved, and the leather can be placed on a hot plate of usually 100 ° C. or higher, preferably 120 to 130 ° C., to give a three-dimensional effect called “ふ”.

Thus, in the finishing process, the leather is often heated, and trivalent chromium contained in the leather after chrome tanning may be changed to hexavalent chromium. However, also in this case, the generated hexavalent chromium can be returned to the trivalent chromium again by the function of the hexavalent chromium reducing compound which is contained in the leather by the hexavalent chromium treatment process.

In this embodiment, since the hexavalent chromium treatment process is performed before the finishing process, the leather obtained in the finishing process can be maintained without losing the appearance. Among reptile leathers used in the present invention, it is preferable that the leather of animals belonging to the order Pectinidae alligator (crocodiles) is high-grade and has a delicate appearance, and that no other treatment is performed after the finishing treatment. For this reason, this embodiment which performs a hexavalent chromium processing process before a finishing process is used suitably especially for manufacture of a crocodile leather.
In the following, the dyeing fatliquoring process and the hexavalent chromium treatment process simultaneously performed in the present embodiment will be described in more detail.

[Stain fatliquing process and hexavalent chromium treatment process]
In the fatliquoring process and the hexavalent chromium treatment process, a hexavalent chromium treatment agent is usually used to simultaneously perform both processes. In the present specification, the hexavalent chromium treating agent used at the same time when the above-mentioned amount step is simultaneously performed is particularly referred to as a simultaneous treating agent.

Said co-treatment agents comprise, together with water, the colorants and oils normally used for dyeing and fatliquing leather. Further, to the above-mentioned co-treatment agent, a surfactant which is usually used for simultaneously performing dyeing and fatliquoring, and a hexavalent chromium reducing compound for performing hexavalent chromium treatment are added.

The hexavalent chromium reducing compound is a compound capable of reducing hexavalent chromium to trivalent chromium.
As such a hexavalent chromium reducing compound, in addition to ascorbic acid described in Patent Document 1, a compound proposed by the present inventor (International Application PCT / JP2015 / 71509 (International Application Date: July 29, 2015) Can be mentioned. Below, the hexavalent chromium reducing compound which this inventor proposed is demonstrated.

The above-mentioned hexavalent chromium reducing compound is a compound capable of reducing hexavalent chromium to trivalent chromium and, for example, at least acts on hexavalent chromium to have trivalent reducing property (reduction to trivalent An organic compound represented by the following formula (1) consisting of C atom, O atom and H atom, which has performance, has a single bond and a double bond between three carbons, and has a hydroxyl group at the center carbon (A) is mentioned. The structure shown in the formula (1) acts on hexavalent chromium and has trivalent reducibility.

In the formula (1), R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently a substituent composed of C, H, O (C, H and optionally O) And the like, preferably contains a carbonyl group of an unsaturated bond, but does not have a reactive functional group such as an aldehyde group or a carboxyl group. Further, it is preferable that the resin does not have functional groups such as amine groups, nitrogen-containing groups such as isocyanate groups, and sulfur-containing groups such as sulfuric acid groups. R ¹ or R ² and any of R ³ , R ⁴ or R ⁵ may be bonded to each other to form a ring.

The compound having a structure represented by the formula (1) may be a cyclic hydrocarbon, and further may be an aromatic hydrocarbon composed of a single ring or a fused ring. In the case of an aromatic hydrocarbon, the π bond is delocalized, not limited to the portion of the double bond between carbon 1 and carbon 2 of the formula (1). The cyclic hydrocarbon or aromatic hydrocarbon may have a substituent.

The organic compound (A) preferably has a structure represented by the formula (1) and a hydroxyl group, and preferably does not have a reactive functional group such as an aldehyde group and a carboxyl group in the structure.

In addition to the organic compound (A) as the hexavalent chromium reducing compound, it has a structure represented by the formula (1) having trivalent reducing property by acting on hexavalent chromium, and hydroxyphenyl It is preferable that the organic compound (B) which does not have a group, an aldehyde group and a carboxyl group is included. Further, it is preferable that the resin does not have functional groups such as amine groups, nitrogen-containing groups such as isocyanate groups, and sulfur-containing groups such as sulfuric acid groups.

Examples of the organic compound (A) or (B) include the following compounds (formulas (2) to (14)) and derivatives thereof. In the present invention, it is also preferable to use a mixture of these.

The carbon 2 in the above formulas (2) to (12) and (14) corresponds to, for example, the carbon 2 in the above formula (1).
The hexavalent chromium reducing compound is an organic compound which acts on harmful hexavalent chromium to cause a harmless compound to chemically change. For example, this compound can reduce hexavalent chromium and render it harmless as trivalent chromium.

In general, lithium aluminum hydride, sodium borohydride, hydrazine, dibutylaluminum hydride, oxalic acid, formic acid and the like are known as reducing agents. There are various problems when using these representative reducing agents.

When lithium aluminum hydride is used, the drug is a powdery strong reducing agent, but it reacts violently with water to generate hydrogen and is flammable and dangerous. Such flammable materials do not withstand use, as leather or leather products are usually exposed to the skin (perspiration) and to rain and the like.

When sodium borohydride is used, the drug is somewhat hygroscopic and easily decomposed by moisture, so it must be sealed and stored. An aqueous solution produced by moisture such as sweat or rain exhibits strong basicity because the drug is a decomposition product. Therefore, it adversely affects the skin (skin) and mucous membranes. It can not be contained in leather or leather products, as it must be stored in an alkaline solution because it decomposes under acidic and neutral conditions to generate hydrogen. It is also difficult to handle because it decomposes in water and generates hydrogen.

Hydrazine is a colorless liquid with a pungent odor resembling ammonia, and it does not withstand use because it produces white smoke on contact with air. It is easily soluble in water, has strong reducibility, is easily decomposed, and is flammable, so it is difficult to handle.

When dibutylaluminum hydride is used, the drug is a colorless liquid but is weak to moisture, so it is difficult to utilize it in the general atmosphere because it is stored and used under an inert gas atmosphere.

When oxalic acid is used, the drug is toxic because it binds strongly to calcium ions in the blood in the body, and it is designated as a medical foreign substance by the poison and the harmful substance control method. The use of such poisons in leather or leather products is purposeless and unacceptable.

When formic acid is used, the liquid formic acid solution or vapor may be harmful to the skin and eyes, and in particular, may cause irreparable damage to the eyes. In addition, if inhaled, it may cause damage such as pulmonary edema and so can not be used. Besides, since chronic exposure is considered to adversely affect the liver and kidneys, and the possibility as a source of allergy is also considered, it does not meet the purpose of the present invention and can not be used.

For these reasons, the present applicants conducted extensive investigations and experiments on hexavalent chromium reducing compounds that can be used for leather or leather products, and found compounds meeting the purpose.
Organic compounds (A) and (B) contained as hexavalent chromium reducing compounds have the basic ability to treat hexavalent chromium and render it harmless, as well as the leather or leather product treated with this which is in contact with the skin In addition, it does not have adverse effects such as rough skin and has no toxicity. Moreover, it is preferable that (A) and (B) are compounds which do not cause decomposition with each other due to their respective reducibility and do not react and can not interfere with each other. The organic compound is preferably a compound having a basic skeleton represented by the above chemical formula (1), and is preferably a stable one comprising atoms of C, H and O.

The organic compound having the structure represented by the chemical formula (1) does not have a functional group such as an aldehyde group or a carboxyl group. Further, it is preferable that the resin does not have functional groups such as amine groups, nitrogen-containing groups such as isocyanate groups, and sulfur-containing groups such as sulfuric acid groups. Such functional groups are not suitable for hexavalent chromium reducing compounds as they are reactive and may cause unexpected reactions during use of leather or leather products. The organic compound acts on hexavalent chromium to form a compound which is not detected as hexavalent, and can render hexavalent chromium harmless.

(Organic compound (A))
The organic compound (A) has a structure represented by the above chemical formula (1) and, for example, a hydroxyphenyl group represented by the following chemical formula (15). By having the functional group, it has immediate action, long and stable retention in leather or leather products, has a reducing action over a long period, and is excellent in heat resistance. Therefore, the formation of hexavalent chromium is suppressed for a long time. In addition, because it is included in leather or leather products, it is difficult to be decomposed even by moisture such as sweat and rain. Although the reason for having such excellent effects is not clear, tanning usually chemically crosslinks and stabilizes collagen which is the main component of the skin. The hydroxyphenyl group possessed by the organic compound (A) is retained particularly because of high interaction with the collagen, while it is not completely incorporated into the collagen and becomes like an island part of a sea-island structure, reducing It is assumed that it is taken in with the degree of freedom that it has. As the organic compound (A), a compound having high safety and low environmental impact is preferable because it is used for leather or leather products.

In the chemical formula (15), R ^a is a monovalent group or a divalent group. The monovalent group includes a hydrogen atom, a hydrocarbon group or an oxygen-containing group. Examples of the divalent group include a divalent hydrocarbon group or a divalent oxygen-containing group. Among these, a hydrogen atom, a monovalent hydrocarbon group, a divalent hydrocarbon group or a hydroxyl group is preferable because more compatibility with leather or leather products can be obtained. R ^{a s} are independent of each other and may be the same or different. However, adjacent groups of R ^{a s} may be bonded to each other to form an aromatic ring or an aliphatic ring. Also, R ^a may be bonded to R ^a of another hydroxyphenyl group. It is preferable that all of R ^a not simultaneously be hydrogen atoms, and in leather or leather products, it is represented by the chemical formula (15) because it has more immediate effect and stably exhibits better reducibility over a long period of time The group is more preferably a dihydroxyphenyl group or a trihydroxyphenyl group, and more preferably a 3,4,5-trihydroxyphenyl group.

The hydrocarbon group is preferably a hydrocarbon group having 1 to 20 carbon atoms, and specifically, an alkyl group having 1 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms, or 6 to 20 carbon atoms An aryl (aryl) group or a substituted aryl (aryl) group etc. are mentioned. For example, methyl group, ethyl group, n-propyl group, isopropyl group, allyl (allyl) group, n-butyl group, isobutyl group, sec-butyl group, t-butyl group, amyl group, n-pentyl group, neopentyl group , N-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decanyl group, 3-methylpentyl group, 1,1-diethylpropyl group, 1,1-dimethylbutyl group, 1- Methyl-1-propylbutyl group, 1,1-dipropylbutyl group, 1,1-dimethyl-2-methylpropyl group, 1-methyl-1-isopropyl-2-methylpropyl group, cyclopentyl group, cyclohexyl group, cyclo Heptyl group, cyclooctyl group, norbornyl group, adamantyl group, phenyl group, o-tolyl group, m-tolyl group, p-tolyl group, xylyl group, iso Ropylphenyl, t-butylphenyl, naphthyl, biphenyl, terphenyl, phenanthryl, anthracenyl, benzyl and cumyl can be mentioned, and oxygen-containing groups such as methoxy, ethoxy and phenoxy are What is included is also mentioned as a hydrocarbon group (for example, alkoxyl group). In addition, unsaturated carboxylic acid esters such as methyl ester, ethyl ester, n-propyl ester, isopropyl ester, n-butyl ester, isobutyl ester, (5-norbornen-2-yl) ester (the unsaturated carboxylic acid is a dicarboxylic acid) In the case of an acid, one containing a monoester or a diester may be mentioned as the hydrocarbon group.

The oxygen-containing group includes a hydroxyl group.
As the organic compound (A), for example, the above chemical formulas (2) to (12) and (14),
Phenol, o-cresol, m-cresol, p-cresol, 2,3-dimethylphenol, 2,5-dimethylphenol, 3,4-dimethylphenol, 3,5-dimethylphenol, 2,4-dimethylphenol, 2 , 6-Dimethylphenol, 2,3,5-trimethylphenol, 3,4,5-trimethylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, BHT (dibutylhydroxytoluene), BHA (Butylhydroxyanisole), 2-phenylphenol, 3-phenylphenol, 4-phenylphenol, 3,5-diphenylphenol, 2-naphthylphenol, 3-naphthylphenol, 4-naphthylphenol, 4-tritylphenol, -Methyl resorcinol, 4-methyl resorcinol, 5-methyl resorcinol, 4-tert-butyl catechol, 2-methoxyphenol, 3-methoxyphenol, 2-propylphenol, 3-propylphenol, 4-propylphenol, 2-isopropylphenol , 3-isopropylphenol, 4-isopropylphenol, 2-methoxy-5-methylphenol, 2-tert-butyl-5-methylphenol, thymol, isothymol, 1-naphthol, 2-naphthol, 2-methyl-1-naphthol , 4-methoxy-1-naphthol, 7-methoxy-2-naphthol,
Dihydroxynaphthalene such as 1,5-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, etc.
Tetrahydroxynaphthalene such as 1,3,6,8-tetrahydroxynaphthalene,
Methyl 3-hydroxy-naphthalene-2-carboxylate, 9-hydroxyanthracene, 1-hydroxypyrene, 1-hydroxyphenanthrene, 9-hydroxyphenanthrene, bisphenol fluorene, phenolphthalein,
Benzophenone derivatives such as 2,3,4-trihydroxybenzophenone and 2,2 ', 3,4-tetrahydroxybenzophenone
Catechol tannins, pyrogallol tannins, pentaploid tannins, gallic acid tannins, tannins such as phlorotannins,
Flavonoids such as anthocyanin, rutin, quercetin, fisetin, daidzein, hesperetin, hespyridine, chrysin, flavonol,
Catechins such as catechin, gallocatechin, catechin gallate, epicatechin, epicarotechin, epicatechin gallate, epicarotechin gallate, procyanidins, theaflavin, etc.
Curcumin, lignan,
Rhododendrol [4- (p-hydroxyphenyl) -2-butanol],
Acetylrhododendrole, hexanoylrhododendrole, octanoylrhododendrole, dodecanoylrhododendrole, tetradecanoylrhododendrole, hexadecanoylrhododendrole, octadecanoylrhododendrole, 4- (3-acetoxy Acyl such as butyl) phenyl acetate, 4- (3-propanoyloxybutyl) phenylpropanoate, 4- (3-octanoyloxybutyl) phenyloctanoate, 4- (3-palmitoyloxybutyl) phenyl palmitate Rhododendrol,
Rhododrole alkyl ether such as 4- (3-methoxybutyl) phenol, 4- (3-ethoxybutyl) phenol and 4- (3-octyloxybutyl) phenol
Rhododrol-D-glucoside (α or β form), Rhododrol-D-galactoside (α or β form), Rhododrole-D-xyloside (α or β form), Rhododrole-D-maltoside ( Rhododendrol glycosides such as α or β form), etc.
Alpha tocopherol, beta tocopherol, gamma tocopherol, delta tocopherol and the like can be mentioned.

Moreover, these derivatives, for example, the compound which has an alkoxyl group, esterified thing, etc. are mentioned. Specifically, for example, pyrogallol-1,3-dimethylether, pyrogallol-1,3-diethylether, 5-propylpyrogallol-1-methylether and the like can be mentioned.

Examples of the organic compound (A) include compounds of the structure (1,2,3-Trihydroxybenzene skeleton) represented by the chemical formula (2) above and derivatives thereof. Such compounds have a hexavalent chromium removal function.

Examples of this derivative include those having a substituent such as a hydrocarbon group or an oxygen-containing group at positions 4, 5, and 6 of the compound represented by the chemical formula (2). Preferred examples of the substituent include a hydrocarbon group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, and an esterified compound having 1 to 20 carbon atoms, more preferably a hydrocarbon group having 1 to 10 carbon atoms and 1 carbon atom. Examples thereof include an alkoxy group of ̃20 and an esterified product having 1 to 10 carbon atoms. These groups are as described above. The same applies to derivatives of the compounds described later. For example, esters of gallic acid such as the compound represented by the chemical formula (3), a compound represented by the chemical formula (4) having a plurality of structures of the chemical formula (2) in one molecule, derivatives of the compound, etc. . Examples thereof include catechol tannins, pyrogallol tannins, pentaploid tannins, tannins such as gallic acid tannins and phlorotannins.

Thus, the substituent introduce | transduced to 4, 5, 6 position can introduce the substituent suitable for each usage. For example, when it is dissolved in an ester solvent and used, an ester group can be introduced to enhance the compatibility.

In the present invention, the organic compound (A) preferably contains (i) an ester of gallic acid and (ii) at least one compound selected from tannic acid and derivatives thereof, and (i) More preferably, it comprises an ester and (ii) tannic acid.

The ester of gallic acid is considered to be easily bled from leather or leather products because of its relatively low molecular weight, but since it has a partial structure of tannic acid, it preferably interacts with tannic acid and its derivatives while maintaining its reducing power. It works and it becomes difficult to bleed. It is also reducible in leather or leather products and has high immediate effect. The reducing power is not as high as that of ascorbic acid, but it is higher than tannic acid, so it exerts the reducing power for a long time even after ascorbic acid decomposes and loses the reducing power (chromium oxidized to hexavalent) Ions can be reduced again). Esters of gallic acid are resistant to moisture such as sweat and rain in leather or leather products and are difficult to be decomposed.

Tannic acid and its derivatives are bulky and have a good affinity to collagen in leather or leather products as they are originally used for tanning treatment, so they are difficult to bleed and can maintain reducing power in leather and leather products over a long period of time . Therefore, the formation of hexavalent chromium can be suppressed for a longer period of time. In addition, tannic acid and its derivatives are highly safe because they are hypoallergenic to human (skin). The reducing power is slower than ascorbic acid and esters of gallic acid, but it has good affinity with leather and leather products and is less likely to be degraded. Therefore, leather products are more effective and less effective than ascorbic acid and esters of gallic acid. It can maintain its reducing power until it reaches its goal.

Therefore, the inclusion of these compounds has high permeability to leather or leather products, can be retained in leather or leather products for a long time, and can be stably reduced over a long period of time. Furthermore, polyphenols are concerned with browning and discoloration due to their strong reducibility, but these compounds are incorporated into leather or leather products before discoloration, so they are difficult to fade or discolor, and leather or It is preferable because there is little risk of impairing the color and texture of leather products.

Further, in the above chemical formula (2), a skeleton having hydroxyl groups at the 1st, 2nd and 3rd positions but having hydroxyl groups introduced similarly to the 1st, 2nd and 4th positions (the above chemical formula (5)) The same effect can be obtained for a compound having a hydroxyl group introduced at the 1st, 3rd and 5th positions (the above chemical formula (6)). In addition, the same effects can be obtained for derivatives.

Further, although three hydroxyl groups are introduced into one aromatic ring in the above chemical formula (2), the compound having one hydroxyl group or the compound having two hydroxyl groups similarly has a hexavalent chromium removing function. Such skeletons include, for example, phenol, BHT, the above chemical formula (7), the above chemical formula (8), the compounds of the above chemical formula (9) and derivatives thereof.

A compound having a hydroxyl group in a compound in which a plurality of aromatic rings are bonded has the same effect. Those having one or a plurality of hydroxyl groups in a naphthalene ring can be mentioned. For example, as a compound which has two hydroxyl groups, there exist what is shown to the said Chemical formula (10) and said Chemical formula (11). The derivative of such a compound also has a hexavalent chromium removing function as the above-mentioned compound.

The same function is exhibited for a compound in which one or more hydroxyl groups are introduced at an arbitrary position with respect to anthracene in which three aromatic rings are linked. As such a compound, for example, there is a compound represented by the above chemical formula (12). These derivatives also have a hexavalent chromium removal function.

Examples of the compound represented by the chemical formula (1) include a compound having a long chain alkyl group and a complex ring. Such compounds are more organic and less soluble in water. However, on the other hand, since the affinity to the organic solvent is high, there is an advantage that it can be dissolved in a hydrocarbon solvent. Examples of the compound include compounds represented by the above chemical formula (14).

Examples of the compound represented by the above chemical formula (1) include catechin, gallocatenine, catechin gallate, epicatechin, epicarocatechine, epicatechin gallate, epicarocatechin gallate, catechins such as procyanidin, theaflavin, and derivatives of catechins. There is also a preference. These catechins are highly safe and highly reducing even in leather or leather products.

(Organic compound (B))
The organic compound (B) has a structure represented by the above chemical formula (1) but does not have, for example, a hydroxyphenyl group shown by the above chemical formula (15). Having no hydroxyphenyl group makes it difficult to penetrate into leather or leather products, but because it has the structure shown in chemical formula (1), hexavalent chromium on the surface of leather or leather products is preferably used as trivalent chromium. It can be reduced and detoxified. Therefore, elution of the hexavalent chromium ion dissolved in water such as sweat or rain and exposure to humans can be suppressed promptly by using the compound (B). Examples of the organic compound (B) include compounds having a heterocycle. Heterocycles include furan, chromene, isochromene, xanthene and the like. Such derivatives include, for example, compounds having the structure shown in the above chemical formula (13) and derivatives thereof, erythorbic acid and derivatives thereof, and 4-hydroxyfuran-2 (5H) -one. Such compounds have a hexavalent chromium removal function.

The derivative of ascorbic acid is not particularly limited. For example, ascorbic acid ester, ascorbic acid phosphoric acid ester, ascorbic acid sulfuric acid ester, ascorbic acid glucoside (2-O-α-D-glucopyranosyl-L-ascorbic acid), ascorbic acid Acid glucosamine, dehydroascorbic acid etc. can be mentioned.

Examples of derivatives of erythorbic acid include erythorbic acid ester and the like.
In the present invention, the organic compound (B) is preferably at least one compound selected from ascorbic acid and erythorbic acid, and more preferably ascorbic acid. The compound is easy to be decomposed and can not realize the effect over a long period, and it is easy to bleed from leather or leather products, but it is less irritating to humans (skin), excellent in safety, high in reducing power and high in immediate effect. . Therefore, the elution of hexavalent chromium ions to the environment and exposure to humans can be effectively and prevented by contacting the leather or the leather product with the simultaneous treatment agent containing the compound (B). In addition, since the surface can be detoxified particularly quickly, it is possible to preferably suppress the onset of rough skin, allergy and the like. The compound (B) does not react with or miscible with the organic compound (A), and is not decomposed by the compound (A). Therefore, the compound (B) can be suitably mixed with the co-treatment agent. In addition, since the compound has a strong reducing power, the organic compound (A) can prevent browning and discoloration. Furthermore, since degradability is high, it is difficult to be colored, and it is preferable because it does not impair the color or texture of leather or leather products.
As described above, hexavalent chromium can be harmlessly removed if it is a compound containing the basic skeleton represented by the chemical formula (1) in the molecule.

(Preferred embodiment of hexavalent chromium reducing compound)
As the hexavalent chromium reducing compound, at least one selected from a compound (Ai) represented by the following formula (Ai) and a tannin (A-ii) is preferable, and is represented by the following formula (Ai) More preferably, the compound (A-i) and the tannin (A-ii) are used in combination.

The compound (Ai) is represented by the following formula (Ai).

In the formula, n represents 0, 1 or 2. That is, the compound (Ai) has a benzene, naphthalene or anthracene structure.
R ¹¹ to R ¹⁸ each independently represent a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a group represented by the following formula (ai). Here, R ¹⁹ represents an alkyl group having 1 to 4 carbon atoms.

Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group and t-butyl group. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, an s-butoxy group and a t-butoxy group.

When n is 0, at least one of R ¹¹ to R ¹⁴ , R ¹⁶ and R ¹⁷ is a hydroxy group. When two of R ¹¹ to R ¹⁴ , R ¹⁶ and R ¹⁷ are a hydroxy group and where three are a hydroxy group, the ability to reduce hexavalent chromium is increased, which is preferable.

When n is 1 or 2, at least one of R ¹¹ to R ¹⁸ is a hydroxy group. When n is 1 or 2, when two of R ¹¹ to R ¹⁸ are hydroxy groups and when three are hydroxy groups, the ability to reduce hexavalent chromium is increased, which is preferable.

When n is 2, a plurality of R ¹⁵ may be the same or different, and the same applies to R ¹⁸ .
R ¹⁶ and R ¹⁷ may be integrated with each other to form a 5- or 6-membered ring, and atoms constituting the ring may contain an oxygen atom in addition to a carbon atom . The ring may have an alkyl group having 1 to 16 carbon atoms as a substituent. The alkyl group having 1 to 16 carbon atoms may be linear or branched.

Specific examples of the compound (Ai) include the compounds represented by the above-mentioned formulas (2), (3), (5) to (12) and (14), and the above-mentioned exemplified compounds. . The compounds (Ai) may be used alone or in combination of two or more.

The tannin (A-ii) may be a hydrolyzable tannin or a condensed tannin. Examples of hydrolyzable tannins include gallotannins such as tannic acid (compound represented by the above formula (4)), ellagitannins and the like. From the viewpoint of preparing the co-treatment agent described later, hydrolyzable tannin is preferably used. Tannins (A-ii) may be used alone or in combination of two or more.

In the compounds (Ai) and tannins (A-ii), carbon to which a hydroxy group is bonded corresponds to, for example, carbon 2 of the above formula (1).
As a hexavalent chromium reducing compound, a compound (Bi) represented by the following formula (Bi) and a following formula (B-ii) together with the compound (Ai) and the tannin (A-ii) It is preferable to use at least one selected from the compounds (B-ii) to be

In the formulae, X represents any of the groups represented by the following formulas (bi) to (b-iii). Here, o represents an integer of 0 to 3, p represents an integer of 1 to 3, and q represents an integer of 1 to 17.

Specifically as a compound (Bi) and a compound (B-ii), the compound represented by Formula (13) mentioned above and the exemplary compound mentioned above are mentioned. The compound (Bi) and the compound (B-ii) may be used alone or in combination of two or more. In addition, the compound (Bi) and the compound (B-ii) may be used in combination.

Treatment of leather with compound (Ai), (A-ii), (Bi) or (B-ii) as the hexavalent chromium reducing compound, ie compounds (Ai), (A) -Ii), (B-i) or (B-ii) is treated to be included in the leather or leather product, not only hexavalent chromium which is present in the leather or leather product before the treatment but also after the treatment The hexavalent chromium generated due to the cause can also be reduced to, for example, harmless trivalent chromium. In other words, the amount of hexavalent chromium can be kept below the regulation value according to Regulation (EU) No. 3014/2014 until the leather or leather product reaches its utility and purpose. In particular, the combination of the fast acting compound (Ai) and the slow acting compound (A-ii) can more surely maintain the condition below the regulatory value until the leather or leather product reaches its effect and purpose. Furthermore, when the compound (Bi) and / or (B-ii) having high reducing power and immediate action is combined with the compound (Ai) and / or (A-ii), the leather or leather product can be treated In particular, hexavalent chromium present near the surface can be effectively reduced.

Specifically, when treating with a hexavalent chromium reducing compound, a co-treatment agent containing a hexavalent chromium reducing compound is used. In the co-treatment agent, the ratio of the organic compounds (A) and (B) is not particularly limited as long as the effects of the present invention are exhibited, but 50 to 90 in weight ratio ((A) :( B)) It is preferably 10 to 50, more preferably 50 to 80: 20 to 50, still more preferably 50 to 70:30 to 50 (however, the sum of (A) and (B) 100% by weight). The organic compound (B) is excellent in immediate action but can not obtain long-term stability because it is difficult to penetrate into leather or leather products. Therefore, the amount of the organic compound (B) is preferably equal to or less than that of the organic compound (A). On the other hand, if it is less than 10% by weight, hexavalent chromium on the surface of the leather or leather product may not be suitably reduced to trivalent chromium and may not be detoxified.

When the co-treatment agent contains the ester of (i) gallic acid, at least one compound selected from (ii) tannic acid and derivatives thereof, and the organic compound (B), the effect of the present invention can be obtained. The ratio by weight percent ratio ((i) :( ii) :( B)) is preferably 1 to 20:30 to 89:10 to 50, and preferably 3 to 17:33 to 77:20. The ratio of ̃50 is more preferable, and the ratio of 5 to 15:35 to 65:30 to 50 is more preferable (however, the total of (i), (ii) and (B) is 100% by weight). The quantitative ratio of the organic compound (A) is as described above. The organic compound (B) is incompatible with the compounds (i) and (ii), is not incorporated into the compound (ii), and can suitably reduce the surface of the leather or leather product, so that ascorbic acid and / or Erythorbic acid is preferred. The compounds (i) and (ii) mainly have an effect of reducing hexavalent chromium in leather or leather products. Ascorbic acid, propyl gallate and tannic acid are used at concentrations used in leather or leather products for carcinogenicity, skin sensitization and skin irritation as defined in the OECD Guidelines for the Testing of Chemicals. Meet the standards of environmental safety. The compound (i) has high reducing power but is relatively easy to be decomposed. On the other hand, since compound (ii) has compound (i) as a partial structure, compound (i) can be obtained by decomposing compound (ii), but the reducing power is less than that of ascorbic acid and gallic acid. It is delayed compared to ester. Therefore, the amount of compound (ii) is preferably larger than that of compound (i). Also, it is pointed out that the compound (i) may have some hypersensitivity to human (skin) compared to the compound (ii) and the organic compound (B), and it may be relatively colored. Since it is also preferred to use in a smaller amount than compound (ii) and organic compound (B). If the amount of compound (i) is less than 1% by weight, the amount of hexavalent chromium in the leather or leather product can not be quickly detoxified and can not be treated with the organic compound (B), or After the deactivation), untreated hexavalent chromium ions may be eluted to the surface. Because polyphenols are strongly reducing, there is a concern that they may be browned or discolored. However, when used in these quantitative ratios, they are more likely to be incorporated into leather or leather products before discoloring, so they are further discolored. It is preferable because it becomes difficult to discolor and hardly impair the color or texture of leather or leather products. Moreover, if it is these quantitative ratios, since it becomes easy to melt | dissolve in both water and an organic solvent, it is preferable. The co-treatment agent is preferred because long-term reliability can be obtained.

When the co-treatment agent contains compound (Ai) and tannin (A-ii), the ratio of compound (Ai) and tannin (A-ii) is particularly limited as long as the effects of the present invention can be exhibited. 11 to 70:30 to 89 are preferable, 23 to 67: 33 to 77 are more preferable, and 35 to 50: 50 to 65 are preferable in terms of a weight% ratio ((Ai): (A-ii)). Further preferred (however, the total of (A-i) and (A-ii) is 100% by weight). Thereby, the state in which hexavalent chromium is reduced can be maintained for a long time.

In addition, when the co-treatment agent contains compound (Ai), tannin (A-ii), and compound (Bi) and / or (B-ii), compound (Ai), tannin The ratio of the total of A-ii) and the compounds (Bi) and (B-ii) is not particularly limited as long as the effects of the present invention can be exhibited, but the ratio by weight ((Ai): (A-ii): ): The total of (Bi) and (B-ii)) is preferably 1 to 20: 30 to 89: 10 to 50, more preferably 3 to 17: 33 to 77: 20 to 50, and 5 to 15). 35 to 65:30 to 50 are more preferable (provided that the total of (Ai), (A-ii), (Bi) and (B-ii) is 100% by weight). The reason why these ratios are preferable is that (i) is (Ai), (ii) is (A-ii), (B) is (Bi) and (B-ii) in the above. Same as replacing.

(Amount of ingredients in co-treatment agent)
In 100% by mass of the co-processing agent, the coloring material and the oil are contained in amounts in the range usually used. The hexavalent chromium reducing compound is contained, for example, in an amount of 0.01 to 10.0% by mass in 100% by mass of the simultaneous treatment agent.

When only the organic compound (A) is used as the hexavalent chromium reducing compound, the amount of the organic compound (A) contained in the simultaneous treatment agent is not particularly limited, but preferably 100% by weight of the simultaneous treatment agent in total. It is about 0.01 to 10.0 (wt%), more preferably about 0.1 to 7.0 (wt%), and still more preferably about 0.3 to 5.0 (wt%), Still more preferably, it is about 0.5 to 3.0 (% by weight), and most preferably about 0.5 to 2.0 (% by weight). Such amounts are preferred as they result in particularly low discoloration or discoloration to leather or leather products. In addition, the hexavalent chromium can be maintained in a reduced state for a long time.

When the organic compounds (A) and (B) are used in combination, the amounts of the organic compounds (A) and (B) contained in the simultaneous treatment agent are not particularly limited, but 100% by weight of the simultaneous treatment agent The total amount is preferably about 0.01 to 10.0 (% by weight), more preferably about 0.1 to 7.0 (% by weight), and still more preferably 0.3 to 5.0 (% by weight) It is more preferably about 0.5 to 3.0 (% by weight), and most preferably about 0.5 to 2.0 (% by weight). Such amounts are preferred as they result in particularly low discoloration or discoloration to leather or leather products. In addition, the hexavalent chromium can be maintained in a reduced state for a long time.

When the co-treatment agent contains compound (A-i) and / or tannin (A-ii) and, if necessary, compound (B-i) and / or (B-ii), these amounts Is the same as in the case where (A) is replaced by the sum of (Ai) and (A-ii) and (B) is replaced by the sum of (Bi) and (B-ii) in the above amounts.

In addition, when the co-treatment agent contains compound (A-i) and / or tannin (A-ii) and, if necessary, compound (B-i) and / or (B-ii), other than the above amounts Also for explanation of (i) (ester of gallic acid) to (Ai), (ii) (tannic acid) to (A-ii), (A) to (Ai) and (A-) The case where (B) is replaced with (Bi) and (B-ii) applies to ii).

The method of preparing the co-treatment agent is not particularly limited as long as the above components can be dissolved. In order to dissolve the hexavalent chromium reducing compound, for example, heating to 50 to 70 ° C. is also preferable.
In the dyeing fatliquoring process and the hexavalent chromium treatment process, the leather and the co-treatment agent are brought into contact with each other, for example, by placing the leather tanned together with the co-treatment agent in a drum.

As a ratio of the leather and the co-treatment agent, the ratio of the leather and the dyeing fatliquor in ordinary dyeing fatliquor can be adopted. Further, as the conditions such as the processing temperature and the processing time, appropriate conditions can be adopted according to the color material.

Thereby, the leather is colored, and flexibility and the like are given.
Also, a hexavalent chromium reducing compound impregnated into the leather reduces hexavalent chromium in the leather to trivalent chromium. Then, the leather is in a state in which the remaining hexavalent chromium reducing compound not used for the reduction is contained together with the trivalent chromium. In the treatment with hexavalent chromium reducing compounds, the leather usually has a content of hexavalent chromium measured according to ISO 17075: 2008-02 of less than 3 ppm, preferably 2 ppm or less. The trivalent chromium content is not particularly limited because it varies depending on the leather, but is usually 4000 ppm or more, and may be 4500 ppm or more, and may be further contained 5000 ppm or more. Also, the total chromium content does not change before and after treatment with the co-treatment agent.

When the above treatment causes the leather to contain the hexavalent chromium reducing compound, even if the harmless chromium is changed to harmful hexavalent chromium after the treatment, this hexavalent chromium is converted to the hexavalent chromium reducing compound. It can be detoxified. That is, the leather treated with the co-treatment agent can maintain the state in which the hexavalent chromium is less than the regulation value until its effect or purpose is reached.

In the method for producing reptile leather according to the present invention, in addition to the above-described steps, a water immersion step, a lime immersion step, a deashing step, a pickle step, a tanning step, a shaving step and a retanning step are usually performed. And the like may be performed as appropriate.

<Other aspects>
Next, other aspects will be described.
In the method of producing reptile leather according to the present invention, in addition to the above-described preferred embodiment [1], a hexavalent chromium treatment step is performed on the chromium-tanned leather in the chromium tanning step, and then to the hexavalent chromium-treated leather Alternatively, it may be a mode [2] in which the dyeing and fatliquoring process is performed, and then the finishing process is performed on the dyed and fatliquored leather. In addition, a dyeing and fatliquoring process is applied to the chrome-tanned leather, then a hexavalent chromium treatment process is applied to the dyed and fatlied leather, and then a finishing process is applied to the hexavalent chromium-treated leather. The embodiment [3] may be performed.

In any of the embodiments [2] and [3], as in the embodiment [1], since the hexavalent chromium treatment step is performed prior to the finishing step, the leather obtained in the finishing step can be retained without any loss of appearance. Aspect [1] is preferable in that the number of steps can be reduced compared to aspects [2] and [3]. In addition, there is a concern that the hexavalent chromium reducing compound in the leather may be released if the dyeing and fatifying step in a solvent is carried out after the hexavalent chromium treatment step. Aspects [1] and [3] are preferable in that there is no such concern.

In the embodiment [2], the hexavalent chromium treatment step is carried out first, but the hexavalent chromium treatment agent used here is a treatment agent obtained by removing the coloring material, oil and surfactant from the above-mentioned simultaneous treatment agent (ie 6 A treating agent containing a chromium-reducing compound and water, which is also referred to as a hexavalent chromium-only treating agent in the present specification, is suitably used. However, the nonionic surfactant may be contained.

The solvent may be water or a mixed solvent of water and an organic solvent. Examples of the organic solvent include alcohols having 1 to 3 carbon atoms (methanol, ethanol, propanol and isopropanol (IPA)), butanol, acetone, methyl ethyl ketone (MEK) and N, N-dimethylformamide (DMF).

In order not to impair the texture of leather, only water or a mixed solvent of water and an alcohol having 1 to 3 carbon atoms is preferable, only water or a mixed solvent of water and IPA is more preferable, and only water is more preferably used. In addition, since the hexavalent chromium treatment process of aspect [2] is performed before fatliquoring, even if a solvent is water, a processing agent is easy to soak in.

In the case of a mixed solvent of water and an organic solvent, the organic solvent is used in an amount of more than 0% by mass and 20% by mass or less, where the total of water and the organic solvent is 100% by mass. Is preferred.

The treatment of leather with the above-described hexavalent chromium treatment, that is, the detoxification of hexavalent chromium, is carried out by bringing the leather containing hexavalent chromium into contact with the hexavalent chromium treatment. The contact method is not particularly limited as long as the effects of the present invention can be obtained, and examples thereof include spraying, spraying, dipping, coating, and immersion. Specifically, the treatment agent may be applied to the leather by spraying with a spray or the like, application by brushing or brushing, or the treatment agent may be included in a cloth to rub the surface. May be processed. In the case of delicate leather such as reptiles, it is preferable to apply by spraying such as spray since the surface is very delicate and easily damaged. In addition, since the hexavalent chromium treatment process of aspect [2] is performed before fatliquoring, the treatment agent is easily infiltrated on the silver side and the back side of the leather.

Furthermore, the appropriate amount of use of the hexavalent chromium treating agent can be appropriately determined in consideration of the thickness, density and the like of leather fibers. In order to appropriately perform the treatment with the hexavalent chromium treating agent, for example, the treating agent containing the hexavalent chromium reducing compound is attached by spray or the like to the treated surface of the leather in the concentration range described above. It is preferable to determine the amount by which the treatment agent starts to exude to the back of the substrate and to treat with this amount. When done in this amount, it is usually possible to keep the hexavalent chromium below regulatory limits until the leather reaches its effectiveness or purpose. In order to determine the appropriate amount of the hexavalent chromium treating agent in advance, it is preferable to use a leather that is as close as possible to the properties of the leather used in the hexavalent chromium treating step, such as the thickness and density of the fibers.

Next, the dyeing fatliquoring step is carried out by a method which is usually carried out, and the dyeing fatliquoring agent used here is a treating agent obtained by removing the hexavalent chromium reducing compound from the above-mentioned co-treatment agent (i.e. coloring material, oil , A surfactant and a treating agent containing water are suitably used.

In the embodiment [3], the dyeing and fatliquoring process is first carried out by a method which is usually carried out, but the dyeing and fatliquoring agent used here is the same as the embodiment [2].
Next, although a hexavalent chromium treatment step is performed, the hexavalent chromium treatment agent used here is the same as in the embodiment [2]. The processing method is also the same as in the embodiment [2]. However, since the hexavalent chromium treatment step of the embodiment [3] is carried out after fatliquoring, the solvent is preferably a mixed solvent of water and an organic solvent, and a mixed solvent of water and an alcohol having 1 to 3 carbon atoms is more preferable. Preferably, a mixed solvent of water and IPA is more preferably used. Moreover, since it is after fatliquoring, the processing agent is more likely to penetrate the back side of the leather. Therefore, it is preferable to apply a treatment to the back of the leather.

The method for producing reptile leather according to the present invention is generally used in addition to water, coloring materials usually used for dyeing leather, and fatliquoring of leather, instead of the co-treatment agent in the embodiment [1]. The embodiment [1 ′] may use a co-treatment agent containing an oil in which the oil is solubilized and a hexavalent chromium reducing compound. Further, the method for producing reptile leather according to the present invention comprises water, a coloring material usually used for dyeing leather, and fatliquoring of leather instead of the coloring fatliquoring agent in the embodiments [2] and [3]. It may be an embodiment [2 '] or [3'] in which a coloring and fatliquoring agent containing an oil obtained by solubilizing a commonly used oil is used.
Furthermore, the method for producing reptile leather according to the present invention is suitably used for producing fish leather as well as reptiles.

<Leather>
The reptile leather of the present invention is a chrome-tanned leather, which can reduce hexavalent chromium to trivalent chromium without concentration gradient from the silver side of the leather to its back side 6 Containing a chromium-reducing compound. In the leather of the present invention, the appearance of the leather applied by the finishing treatment is maintained as it is. The leather of the present invention is obtained, for example, by the above-described method of manufacturing leather.

<Production method of leather products and leather products>
The leather product of the present invention includes a processing step of manufacturing leather by the above-described method of manufacturing leather and then processing the leather. In the manufacturing method of the above-mentioned leather goods, the appearance of leather given by finishing processing in the manufacturing process of leather is kept as it is.

As leather products (processed leather products), for example, shoes, clothing, hats, gloves, belts, wallets, business card holders, watch bands, bags, book covers, brushstrokes, cell phone cases, system organizers, key cases, glasses cases There is a tool case.

The processing steps are carried out in the usual manner. Specifically, a leather product is obtained by cutting a leather sheet into a required shape, and bonding the core material and the leather to each other with an adhesive or sewing. For example, in the case of a watch band, leather obtained by cutting the band shape around the core material, that is, the front surface and the back surface, is bonded with an adhesive and obtained by heating. Also, depending on the product, it will sew the surroundings to create a textured finish.

The leather product of the present invention includes the above-mentioned leather. An example of a leather product (processed leather product) is as described above. In the above-mentioned leather product, the appearance of the leather given by the finishing treatment in the manufacturing process of the leather is maintained as it is. Further, the leather product of the present invention can be obtained, for example, by the above-described method of manufacturing a leather product.

As mentioned above, the present invention relates to the following.
[1]
Chromium tanning process to obtain leather by chrome tanning the skin of reptiles, dyeing and fatliquoring process to simultaneously dye and fatliquor to chrome tanned leather, and to leather that has been dyed and fatliqued A process for producing reptile leather comprising the steps of finishing and
Furthermore, it includes a hexavalent chromium treatment step of depositing a hexavalent chromium reducing compound capable of reducing hexavalent chromium to trivalent chromium before being subjected to the finishing step to the chrome-tanned leather in the chromium tanning step. A method of producing leather characterized by

According to the above manufacturing method, in the leather manufacturing process, the leather can be treated with a hexavalent chromium treatment agent without changing the appearance.
[2]
[1] The method for producing reptile leather according to [1], wherein the process of dyeing and fatliquoring and the step of treating hexavalent chromium are simultaneously performed on the chrome-tanned leather.

In the above-mentioned leather, the appearance of the leather given by the finishing treatment is maintained as it is.
[3]
The hexavalent chromium reducing compound acts on hexavalent chromium to have a trivalent reducing structure, a structure represented by the chemical formula (1) and a hydroxyphenyl group, and does not have an aldehyde group and a carboxyl group. It is an organic compound (A), The manufacturing method of the leather as described in [1] or [2] characterized by the above-mentioned.

(R ¹ , R ² , R ³ , R ⁴ and R ⁵ are each independently a substituent composed of C, H, O. R ¹ or R ² and R ³ , R ⁴ or R ⁵ And any of the above may be bonded to each other to form a ring).

[4]
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium, a dihydroxyphenyl group or a trihydroxyphenyl group, and an aldehyde group and It is a compound which does not have a carboxyl group, The manufacturing method of the leather as described in [3] characterized by the above-mentioned.

[5]
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium and a 3,4,5-trihydroxyphenyl group, and an aldehyde group And a compound having no carboxyl group, wherein the method for producing leather according to [4].

[6]
The organic compound (A) is
(I) esters of gallic acid,
(Ii) The method for producing leather according to [5], which is at least one compound selected from tannic acid and its derivatives.

[7]
The method according to [6], wherein the compound (ii) is tannic acid.

[8]
The hexavalent chromium reducing compound further has a structure represented by the chemical formula (1) having a reducibility to trivalent by acting on hexavalent chromium, and having a hydroxyphenyl group, an aldehyde group and a carboxyl group. The method for producing leather according to any one of [3] to [7], which contains no organic compound (B).

[9]
The method for producing leather according to [8], wherein the organic compound (B) is at least one compound selected from ascorbic acid, derivatives of ascorbic acid, erythorbic acid and derivatives of erythorbic acid.

[10]
The hexavalent chromium reducing compound is at least one selected from a compound (Ai) represented by the following formula (Ai) and a tannin (A-ii) [1] or [A] 2] The manufacturing method of the leather as described in.

(N represents 0, 1 or 2. Each of R ¹¹ to R ¹⁸ independently represents a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or and a group represented by ai) (R ¹⁹ represents an alkyl group having 1 to 4 carbon atoms) When n is 0, at least one of R ¹¹ to R ¹⁴ , R ¹⁶ and R ¹⁷ And n is 1 or 2. At least one of R ¹¹ to R ¹⁸ is a hydroxy group when n is 1 or 2. When n is 2, plural R ^{15 s} may be the same or different. And the same applies to R ^18. R ¹⁶ and R ¹⁷ may be combined with each other to form a 5- or 6-membered ring, and the ring has 1 to 6 carbon atoms as a substituent. It may have 16 alkyl groups).

[11]
The hexavalent chromium reducing compound is at least one selected from a compound (Bi) further represented by the following formula (Bi) and a compound (B-ii) represented by the following formula (B-ii) [10] The method for producing a leather according to [10], comprising:

(X represents a group represented by the following formulas (bi) to (b-iii) (where R represents an integer of 0 to 3, p represents an integer of 1 to 3, q represents 1 to Represents an integer of 17.))

When the hexavalent chromium reducing compound described in the above [3] to [11] is used, the amount of hexavalent chromium is less than the regulation value according to Regulation (EU) No. 3014/2014 until the leather or leather product reaches its effect and purpose Can maintain the condition of

[12]
A chrome-tanned leather, wherein the leather comprises a hexavalent chromium reducing compound capable of reducing hexavalent chromium to trivalent chromium without a concentration gradient from the silver side of the leather to its back side Reptile leather to feature.

In the above-mentioned leather, the appearance of the leather given by the finishing treatment is maintained as it is.
[13]
The hexavalent chromium reducing compound acts on hexavalent chromium to have a trivalent reducing structure, a structure represented by the chemical formula (1) and a hydroxyphenyl group, and does not have an aldehyde group and a carboxyl group. The leather according to [12], which is an organic compound (A).

[14]
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium, a dihydroxyphenyl group or a trihydroxyphenyl group, and an aldehyde group and The leather according to [13], which is a compound having no carboxyl group.

[15]
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium and a 3,4,5-trihydroxyphenyl group, and an aldehyde group And a compound having no carboxyl group, the leather according to [14].

[16]
The organic compound (A) is
(I) esters of gallic acid,
(Ii) The leather according to [15], which is at least one compound selected from tannic acid and its derivatives.

[17]
The leather according to [16], wherein the compound (ii) is tannic acid.
[18]
The hexavalent chromium reducing compound further has a structure represented by the chemical formula (1) having a reducibility to trivalent by acting on hexavalent chromium, and having a hydroxyphenyl group, an aldehyde group and a carboxyl group. The leather according to any one of [13] to [17], which is characterized by not containing an organic compound (B).

[19]
The leather according to [18], wherein the organic compound (B) is at least one compound selected from ascorbic acid, derivatives of ascorbic acid, erythorbic acid and derivatives of erythorbic acid.

[20]
The hexavalent chromium reducing compound is at least one selected from a compound (Ai) represented by the following formula (Ai) and a tannin (A-ii), as described in [12]. Leather.

[21]
The hexavalent chromium reducing compound is at least one selected from a compound (Bi) further represented by the following formula (Bi) and a compound (B-ii) represented by the following formula (B-ii) The leather according to [20], characterized in that it includes.

When the hexavalent chromium reducing compound described in the above [13] to [21] is used, the amount of hexavalent chromium is less than the regulation value according to Regulation (EU) No. 3014/2014 until the leather or leather product reaches its effect and purpose Can maintain the condition of

[22]
A method for producing a leather product, comprising a processing step of producing a leather by the method of producing a leather according to any one of [1] to [11] and then processing the leather.

[23]
[13] A leather product comprising the leather according to any one of [12] to [21].
In the method of manufacturing the leather product or the leather product, the appearance of the leather applied by the finishing treatment is maintained as it is.

[Example]
EXAMPLES The present invention will next be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

Example 1-1
A chrome-tanned crocodile leather sheet (thickness 1.5 mm) was prepared in the chrome-tanning process. The content of hexavalent chromium determined by the method of ISO 17075: 2008-02 was 8 ppm for this leather. The total chromium content was analyzed by a fluorescent X-ray analyzer (energy dispersive fluorescent X-ray analyzer, JSX-3202EV ELEMENT ANALYZER manufactured by JEOL Ltd.) to be 7141 ppm. As a reference sample, JSX3000 series reference sample 1, JSX3000 series reference sample 2 and JSX3000 series energy calibration reference sample manufactured by Nippon Denshi Co., Ltd. were used. The measurement was carried out by Plastic D3 following JSX starter based on Nippon Electronics Co., Ltd. data QuickManual (No. EY07007-J00, J00 EY07007G, August 2007 version).

About this leather, a dyeing fatliquoring process and a hexavalent chromium treatment process were simultaneously performed as follows. 0.5 parts by weight of the compound represented by the chemical formula (3), 2.5 parts by weight of the compound represented by the chemical formula (4) and the compound represented by the chemical formula (13) with water, a colorant, an oil and a surfactant The compound (2.0 parts by weight) was mixed and dissolved to obtain a simultaneous treatment agent. Here, water was used so that the total amount of the treatment agent was 500 parts by weight.

The leather sheet and co-treatment agent were placed in the drum and processing was performed while rotating the drum.
After drying, part of the leather was cut off, and the content of hexavalent chromium was measured according to ISO 17075: 2008-02. As a result, hexavalent chromium was below the detection limit (2 ppm). The total chromium content, as analyzed by a fluorescent X-ray analyzer, did not change from that before the treatment with the hexavalent chromium treatment agent.

Another part of the leather is examined with the following test solution capable of detecting the hexavalent chromium reducing compound, and the leather contains the hexavalent chromium reducing compound without concentration gradient from the silver side of the leather to its back surface It was confirmed.

This test liquid, when dropped on leather, develops a blue color if the leather contains a hexavalent chromium reducing compound. In addition, as the amount of the hexavalent chromium reducing compound contained in leather increases, darker color is observed. Test for shaving samples 0.5 mm in the thickness direction from the silver side, ie shaving samples from silver side of leather to 0.5 mm, shaving samples from 0.5 mm to 1.0 mm and remaining samples When the solution was dropped, color was developed with the same thickness.

(Test fluid)
Water and IPA were mixed at a ratio of 50: 50 (weight% ratio) to prepare an aqueous solvent. 5 g of iron (III) chloride was dissolved in 95 g of the above aqueous solvent to prepare a test solution containing iron (III) chloride at a concentration of 5% by mass.
Furthermore, glazing processing was performed on the leather (the remainder of the above leather) that had been subjected to the dyeing fatliquoring process and the hexavalent chromium treatment process, to obtain a glossy crocodile leather.

Example 1-2
Instead of 0.5 parts by weight of the compound represented by the chemical formula (3), 2.5 parts by weight of the compound represented by the chemical formula (4), and 2.0 parts by weight of the compound represented by the chemical formula (13), The dyeing and fatliquoring step and the hexavalent chromium treatment step were simultaneously carried out in the same manner as in Example 1-1 except that 1.5 parts by weight of the compound shown and 3.5 parts by weight of the compound shown by the chemical formula (4) were used. The leather treated with the co-treatment agent was obtained.

After drying, part of the leather was cut off, and the content of hexavalent chromium was measured according to ISO 17075: 2008-02. As a result, hexavalent chromium was below the detection limit (2 ppm). The total chromium content, as analyzed by a fluorescent X-ray analyzer, did not change from that before the treatment with the hexavalent chromium treatment agent.

When another part of the leather was examined with the test solution, it was confirmed that the leather contained a hexavalent chromium reducing compound without concentration gradient from the silver side of the leather to its back surface. The inspection was conducted in the same manner as in Example 1-1.
Furthermore, glazing processing was performed on the leather (the remainder of the above leather) that had been subjected to the dyeing fatliquoring process and the hexavalent chromium treatment process, to obtain a glossy crocodile leather.

Example 1-3
Instead of 0.5 parts by weight of the compound represented by the chemical formula (3), 2.5 parts by weight of the compound represented by the chemical formula (4), and 2.0 parts by weight of the compound represented by the chemical formula (13), A dyeing and fatliquoring step and a hexavalent chromium treatment step were simultaneously carried out in the same manner as in Example 1-1 except that 15 parts by weight of the compound shown was used to obtain a leather treated with a simultaneous treatment agent.

Example 2
A chrome-tanned crocodile leather sheet (thickness 1.5 mm) was prepared in the chrome-tanning process. The content of hexavalent chromium determined by the method of ISO 17075: 2008-02 was 8 ppm for this leather. Further, when the content of total chromium was analyzed by a fluorescent X-ray analyzer, it was 7141 ppm.

This leather was subjected to a hexavalent chromium treatment process as follows. 0.5 parts by weight of the compound represented by the chemical formula (3), 2.5 parts by weight of the compound represented by the chemical formula (4) and 2.0 parts by weight of the compound represented by the chemical formula (13) with respect to water It melt | dissolved and obtained the hexavalent chromium processing agent. Here, water was used so that the total amount of the treatment agent was 500 parts by weight.

After soaking the crocodile leather in the obtained treatment agent, it was dried to obtain a leather treated with a hexavalent chromium treatment agent.
Next, the above-mentioned leather was subjected to a dyeing fatliquoring process with a dyeing fatliquor containing a coloring material, oil and surfactant.

[Example 3]
A chrome-tanned crocodile leather sheet (thickness 1.5 mm) was prepared in the chrome-tanning process. The content of hexavalent chromium determined by the method of ISO 17075: 2008-02 was 8 ppm for this leather. Further, when the content of total chromium was analyzed by a fluorescent X-ray analyzer, it was 7141 ppm.

The leather was subjected to a dyeing fatliquoring process with a dyeing fatliquoring agent containing a coloring material, oil and surfactant.
Next, a hexavalent chromium treatment process was performed on the leather as follows. 0.5 parts by weight of the compound represented by the chemical formula (3), 2.5 parts by weight of the compound represented by the chemical formula (4) and the chemical formula (13) with respect to a mixed solvent of water and IPA (50% by weight: 50% by weight) 2.0 parts by weight of the compound represented by the above were mixed and dissolved to obtain a hexavalent chromium treating agent. Here, the mixed solvent was used such that the total amount of the processing agent was 500 parts by weight.

After soaking the crocodile leather in the obtained treatment agent, it was dried to obtain a leather treated with a hexavalent chromium treatment agent.
After drying, part of the leather was cut off, and the content of hexavalent chromium was measured according to ISO 17075: 2008-02. As a result, hexavalent chromium was below the detection limit (2 ppm). The total chromium content, as analyzed by a fluorescent X-ray analyzer, did not change from that before the treatment with the hexavalent chromium treatment agent.

When another part of the leather was examined with the test solution, it was confirmed that the leather contained a hexavalent chromium reducing compound without concentration gradient from the silver side of the leather to its back surface. The inspection was conducted in the same manner as in Example 1-1.

Furthermore, glazing processing was performed on the leather (the remainder of the above leather) that had been subjected to the dyeing fatliquoring process and the hexavalent chromium treatment process, to obtain a glossy crocodile leather.

Claims

Chromium tanning process to obtain leather by chrome tanning the skin of reptiles, dyeing and fatliquoring process to simultaneously dye and fatliquor to chrome tanned leather, and to leather that has been dyed and fatliqued A process for producing reptile leather comprising the steps of finishing and
Furthermore, it includes a hexavalent chromium treatment step of depositing a hexavalent chromium reducing compound capable of reducing hexavalent chromium to trivalent chromium before being subjected to the finishing step to the chrome-tanned leather in the chromium tanning step. A method of producing leather characterized by
The method for producing leather according to claim 1, wherein the dyeing and fatliquoring process and the hexavalent chromium treatment process are simultaneously performed on the chrome-tanned leather.
The hexavalent chromium reducing compound acts on hexavalent chromium to have a trivalent reducing structure, a structure represented by the chemical formula (1) and a hydroxyphenyl group, and does not have an aldehyde group and a carboxyl group. It is an organic compound (A), The manufacturing method of the leather of Claim 1 or 2 characterized by the above-mentioned.

(R 1 , R 2 , R 3 , R 4 and R 5 are each independently a substituent composed of C, H, O. R 1 or R 2 and R 3 , R 4 or R 5 And any of the above may be bonded to each other to form a ring).
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium, a dihydroxyphenyl group or a trihydroxyphenyl group, and an aldehyde group and It is a compound which does not have a carboxyl group, The manufacturing method of the leather of Claim 3 characterized by the above-mentioned.
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium and a 3,4,5-trihydroxyphenyl group, and an aldehyde group And a compound which does not have a carboxyl group.
The organic compound (A) is
(I) esters of gallic acid,
(Ii) At least one compound selected from tannic acid and its derivative, and the manufacturing method of the leather of Claim 5 characterized by the above-mentioned.
The method according to claim 6, wherein the compound (ii) is tannic acid.
The hexavalent chromium reducing compound further has a structure represented by the chemical formula (1) having a reducibility to trivalent by acting on hexavalent chromium, and having a hydroxyphenyl group, an aldehyde group and a carboxyl group. The method for producing leather according to any one of claims 3 to 7, which further comprises an organic compound (B).
9. The method according to claim 8, wherein the organic compound (B) is at least one compound selected from ascorbic acid, derivatives of ascorbic acid, erythorbic acid and derivatives of erythorbic acid.
The compound according to claim 1 or 2, wherein the hexavalent chromium reducing compound is at least one selected from a compound (Ai) represented by the following formula (Ai) and a tannin (A-ii). The method of manufacturing leather described in.

(N represents 0, 1 or 2. Each of R 11 to R 18 independently represents a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or and a group represented by ai) (R 19 represents an alkyl group having 1 to 4 carbon atoms) When n is 0, at least one of R 11 to R 14 , R 16 and R 17 And n is 1 or 2. At least one of R 11 to R 18 is a hydroxy group when n is 1 or 2. When n is 2, plural R 15 s may be the same or different. And the same applies to R 18. R 16 and R 17 may be combined with each other to form a 5- or 6-membered ring, and the ring has 1 to 6 carbon atoms as a substituent. It may have 16 alkyl groups).
The hexavalent chromium reducing compound is at least one selected from a compound (Bi) further represented by the following formula (Bi) and a compound (B-ii) represented by the following formula (B-ii) The method according to claim 10, further comprising:

(X represents a group represented by the following formulas (bi) to (b-iii) (where R represents an integer of 0 to 3, p represents an integer of 1 to 3, q represents 1 to Represents an integer of 17.))
A chrome-tanned leather, wherein the leather comprises a hexavalent chromium reducing compound capable of reducing hexavalent chromium to trivalent chromium without a concentration gradient from the silver side of the leather to its back side Reptile leather to feature.
The hexavalent chromium reducing compound acts on hexavalent chromium to have a trivalent reducing structure, a structure represented by the chemical formula (1) and a hydroxyphenyl group, and does not have an aldehyde group and a carboxyl group. The leather according to claim 12, which is an organic compound (A).

(R 1 , R 2 , R 3 , R 4 and R 5 are each independently a substituent composed of C, H, O. R 1 or R 2 and R 3 , R 4 or R 5 And any of the above may be bonded to each other to form a ring).
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium, a dihydroxyphenyl group or a trihydroxyphenyl group, and an aldehyde group and The leather according to claim 13, which is a compound having no carboxyl group.
The organic compound (A) has a structure represented by the chemical formula (1) having a reducibility of trivalent by acting on hexavalent chromium and a 3,4,5-trihydroxyphenyl group, and an aldehyde group The leather according to claim 14, wherein the leather is a compound having no carboxyl group.
The organic compound (A) is
(I) esters of gallic acid,
(Ii) Leather according to claim 15, characterized in that it is at least one compound selected from tannic acid and its derivatives.
17. Leather according to claim 16, characterized in that the compound (ii) is tannic acid.
The hexavalent chromium reducing compound further has a structure represented by the chemical formula (1) having a reducibility to trivalent by acting on hexavalent chromium, and having a hydroxyphenyl group, an aldehyde group and a carboxyl group. The leather according to any one of claims 13 to 17, which contains no organic compound (B).
The leather according to claim 18, wherein the organic compound (B) is at least one compound selected from ascorbic acid, derivatives of ascorbic acid, erythorbic acid and derivatives of erythorbic acid.
The compound according to claim 12, wherein the hexavalent chromium reducing compound is at least one selected from a compound (Ai) represented by the following formula (Ai) and a tannin (A-ii). Leather.

(N represents 0, 1 or 2. Each of R 11 to R 18 independently represents a hydrogen atom, a hydroxy group, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or and a group represented by ai) (R 19 represents an alkyl group having 1 to 4 carbon atoms) When n is 0, at least one of R 11 to R 14 , R 16 and R 17 And n is 1 or 2. At least one of R 11 to R 18 is a hydroxy group when n is 1 or 2. When n is 2, plural R 15 s may be the same or different. And the same applies to R 18. R 16 and R 17 may be combined with each other to form a 5- or 6-membered ring, and the ring has 1 to 6 carbon atoms as a substituent. It may have 16 alkyl groups).
The hexavalent chromium reducing compound is at least one selected from a compound (Bi) further represented by the following formula (Bi) and a compound (B-ii) represented by the following formula (B-ii) 21. Leather according to claim 20, characterized in that it comprises.

(X represents a group represented by the following formulas (bi) to (b-iii) (where R represents an integer of 0 to 3, p represents an integer of 1 to 3, q represents 1 to Represents an integer of 17.))
A method of producing a leather product, comprising a processing step of producing a leather by the method of producing a leather according to any one of claims 1 to 11, and then processing the leather.
A leather product comprising the leather according to any one of claims 12 to 21.