Method for producing tanned leather including the use of a silyl compound and tanned leather obtained by said method

Abstract

The present invention relates to finished tanned leather having at least one upgrading property imparted by at least one silyl-based treatment agent, and to a method for producing such finished tanned leather, which comprises using a silyl compound during the tanning step and / or the upgrading step following tanning.

Description

[Technical Field]

[0001] The present invention relates to finished tanned leather having at least one upgrading property imparted by a silyl-based treatment agent, and to a method for producing such finished tanned leather, which comprises using a silyl compound in the tanning step and / or in the upgrading step following tanning. [Background technology]

[0002] The transformation of raw hides into tanned leather involves many steps, all of which can be divided into three broad groups defined as follows: (i) the steps of processing the raw hides, (ii) the steps of tanning, and (iii) the steps of refinement.

[0003] In the raw hide processing step, raw hides from animals are received. These raw hides are sorted based on the presence of defects, quality, size, weight, etc. During this processing step, parts that are not desired to remain, such as legs, are cut off and removed. The raw hides are then washed. For this, the raw hides are immersed in a large amount of water, for example in a drum (a rotating barrel) or a paddle (a stationary container with moving blades). Preservatives may be added. After washing, the hair is removed from the raw hides, for example by chemical means. The raw hides are also subjected to a fleshing step in which the subcutaneous tissue is removed. These steps are called the river step.

[0004] At the end of the raw hide processing step, raw hide is obtained, which may be so-called "pickled" raw hide or so-called "demineralized" raw hide. "Pickled" raw hide has a high salt content and a low pH, generally below 3.0. "Demineralized" raw hide finishes the process with a pH generally between 7.5 and 9.0.

[0005] During the tanning process, hides treated as described above, such as "pickled" hides and "demineralized" hides, are degreased. If necessary, they are rehydrated. At this stage, the hides are perishable and ready for tanning. The tanning step itself consists of a chemical process that transforms the perishable hides into perishable, durable tanned leather. This chemical process uses tanning agents. Hides are made up of collagen fibers. During tanning, the tanning agents create bonds between the collagen fibers of the hides, stabilizing them and transforming them into durable, perishable tanned leather.

[0006] A variety of tanning agents are available for tanning raw hides.

[0007] The most widely used tanning agent in the leather industry is chromium in the oxidation state 3 (Cr 3+ ) In fact, Cr 3+ The chrome tanning process is easy and efficient to carry out and allows obtaining tanned leather with properties that meet market expectations.

[0008] Other metals such as aluminum, iron, titanium or zirconium can be used as tanning agents. Silicic acid (Si(OH)4) can also be used as a tanning agent.

[0009] Glutaraldehyde, as well as vegetable tannins or synthetic organic compounds, can also be used as tanning agents.

[0010] At the end of the tanning step, the resulting tanned leather is drained, rinsed and optionally wrung out.

[0011] The refinement steps are those steps which make it possible to use the tanned leather obtained at the end of the tanning step for the manufacture of tanned leather products. In other words, these steps make it possible to obtain finished tanned leather. The refinement steps include the polishing step and the finishing step.

[0012] The polishing step can be carried out in a dry or wet environment. These steps may include, among others, re-tanning, dyeing, fatliquoring, squeezing, staking, and thickness adjustment. Re-tanning gives the tanned leather a certain hardness. In the leather tanning industry, this is also called "decorating" or "rounding" the tanned leather. This re-tanning is generally carried out using a treatment agent. The treatment agent can be a chemical substance such as polyphenols, resins, or even metals, and is added to the tanned leather in an aqueous solution, for example, in a drum. The conditions of temperature, agitation, duration, and pH can be determined by a person skilled in the art depending on the desired result. In dyeing, color is imparted to the tanned leather. This step can also be carried out using a treatment agent, i.e., in the case of dyeing, a colorant in particular. Similar to re-tanning, the dyeing step can be carried out by mixing the tanned leather with a colorant in an aqueous medium in a drum, using a method and conditions of temperature, agitation, duration, and pH that can be determined by a person skilled in the art. The fatliquoring step is a step in which the tanned leather is fatliquored to soften it. This can be carried out using a treatment agent such as a fatliquoring agent, for example, a compound containing one or more fatty chains in its composition, i.e., one or more fatty acids. The fatliquoring step is also generally carried out in an aqueous medium, for example, in a drum, by mixing the tanned leather with a compound containing a fatty chain, using a method that can be determined by a person skilled in the art depending on the desired results. Netting involves stretching the tanned leather, for example, to make it more flexible. Netting can be carried out mechanically. Thickness adjustment involves adjusting the thickness of the tanned raw hide according to the desired thickness of the finished tanned leather. The thickness adjustment process can be carried out mechanically using a device provided for this purpose.

[0013] The finishing step generally takes place outside the drum, i.e., in the ambient environment, and involves finishing the surface of the tanned leather. The finishing step generally involves a combination of mechanical actions (e.g., smoothing, printing, etc.) and treatments, such as film-forming compounds, that assist in achieving the desired effect. The finishing step can, for example, impart aesthetic properties to the tanned leather. Aesthetic properties, such as color, can be achieved by printing a colorant onto the tanned leather. The aesthetic properties can be glossy, velvet-like, matte, satin-like, or grained appearances, and can be achieved, for example, by mechanically processing the tanned leather using smoothing plates, rotary presses, satin-finishing machines, graining machines, etc., using film-forming compounds that can impart gloss, velvet-like, satin-like, or other properties. The finishing step can also impart protective properties to the tanned leather to extend its lifespan. The protective properties can be, for example, resistance to stains, abrasion, water, especially salt water, and resistance to light, especially sunlight. Furthermore, these protective properties can also be obtained by mechanically processing the tanned leather with a treatment, as described above. The treatment is, for example, a film-forming compound that provides the tanned leather with resistance to stains, abrasion, water, light, etc.

[0014] Thus, refinement steps, such as burnishing and finishing steps, are performed to impart one or more properties to the tanned leather, typically using treatments such as, but not limited to, those described above. The treatments may be retanning agents, such as polyphenols and metals, dyeing agents, such as colorants, fatliquoring agents, such as compounds that contain one or more fatty acids in their composition, aesthetic enhancers, such as compounds capable of imparting a gloss, velvet look, matte finish, satin look, or grain, or protective agents, such as compounds that impart resistance to stains, abrasion, water, light, etc. to the tanned leather. Summary of the Invention

[0015] However, existing methods for producing finished tanned leather can result in the degradation of the properties imparted to leather products made from the finished tanned leather during use, during the product's lifespan, or when the product is used under certain environmental conditions. Color transfer has been observed. This color transfer can occur in both humid and dry environments, resulting in the transfer of some of the coloring agent that gave the tanned leather its color to other surfaces, such as the user's skin. A migration phenomenon, known in the leather tanning industry as "PVC (polyvinyl chloride) migration," has also been observed. When colored, finished tanned leather is used in a product with other materials, the coloring agent used to color the tanned leather can partially migrate to the other materials, resulting in a deterioration of the product's original aesthetic appearance. Poor light stability has also been observed with some colorants. Undesirable yellowing can also be observed in finished tanned leather when it has been fatliquored with a fatty acid-containing fatliquoring agent. Decomposition of fatty acids over time causes yellowing, which detracts from the initial aesthetic appearance of the product.

[0016] Therefore, according to conventional methods of manufacturing tanned leather, during the life of a leather product made from such finished tanned leather, at least a portion of the treatment applied to the tanned leather in the upgrading step is likely to separate from the finished tanned leather, which is an undesirable phenomenon.

[0017] Document CN 111 500 799 A1 describes a method for tanning and retanning buffalo hides using polymeric silane coupling agents.

[0018] Therefore, there remains a need for a method for producing finished tanned leather that allows one or more treatments to impart one or more aesthetic properties and that allow the treatments to remain optimally fixed to the tanned leather throughout its life, regardless of the environment in which the finished tanned leather is used.

[0019] The Applicant has developed a method for producing finished tanned leather, which allows one or more treatments to be fixed to the tanned leather in an optimal and durable manner. To this end, the production method according to the invention comprises the use of at least one silyl-based treatment in the tanning step and / or in the subsequent upgrading step, the tanning step comprising the use of a silicic acid precursor of (Si(OH)4).

[0020] The object of the present invention is to provide a finished tanned leather having enhanced properties imparted by at least one silylating agent, which is covalently bonded to a three-dimensional Si-O-Si network, which in turn is bonded to the collagen constituting the finished tanned leather by hydrogen, ionic or covalent bonds.

[0021] Another object of the present invention relates to the production of finished tanned leather from rawhide according to the invention, said method comprising at least (i) processing raw hides to obtain raw hides ready for tanning; (ii) tanning the raw hides of step (i) with at least one tanning agent of formula (I) [C1] Contains JPEG2025538513000002.jpg43170.

[0022] where Y 1 , Y 2 , Y 3 and Y 4 may be the same or different and independently represent a halogen atom, -[OSiO u R 1 3-u ] v group, -O-[SiO u H u-1 R 1 3-u ] v -H group or -OR 2 group, and two or more -[OSiO u R 1 3-u ] v group, -O-[SiOu H u-1 R 1 3-u ] v -H group and -OR 2 The groups may be covalently bonded to one another, wherein u is an integer between 0 and 3, v is an integer greater than or equal to 1, and R 1 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 1 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; ·R 2 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 2 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; The method is characterized in that at least one silyl-based treatment agent is used in the tanning step (ii) and / or in the upgrading step (iii) following the tanning step (II).

[0023] Y 1 , Y 2 , Y 3 and Y 4 may be the same or different and independently represent a halogen atom, —O—[SiO u H u-1 R 1 3-u ] v -H group or -OR 2 Preferably, Y is selected from the group 1 , Y 2 , Y 3 and Y 4may be the same or different and independently represent a halogen atom or -OR 2 It is preferably selected from the group:

[0024] Another object of the present invention relates to the production of finished tanned leather from rawhide according to the invention, said method comprising at least (a) processing raw hides to obtain raw hides ready for tanning; (b) tanning and upgrading the raw hides of step (a) with a treatment composition containing at least the silyl-based treatment agent.

[0025] The invention also relates to finished tanned leather having at least one refined property apparently obtained by these methods.

[0026] The present invention also relates to a method for de-glazing the finished tanned leather obtained by the method according to the invention, said method comprising at least one step of immersing the finished tanned leather in a basic solution to bring the pH of the tanned leather to a value above 10.5, preferably in the range from 11.5 to 13.0.

[0027] The method according to the present invention allows for the production of finished tanned leather with particularly stable refinement properties over time and in use. The raw hide, ready for tanning, contains collagen fibers. The compound used in step (ii) or step (a) according to the present invention is a precursor of Si(OH)4. Polymerization of Si(OH)4 during the tanning step results in the formation of a three-dimensional network of Si-O-Si bonds bonded to the collagen constituting the raw hide. This three-dimensional network stabilizes the raw hide and thus tans it. The advantage of this method is that during the tanning process, some of the silicon atoms of Si(OH)4 do not react and remain within the three-dimensional network. The three-dimensional network thus formed has residues on its surface in the form of silanol groups (Si-OH). These groups allow for the covalent and controlled modification of the tanned leather.

[0028] Thus, the use of silyl-based treatment agents in the tanning step and / or subsequent upgrading steps allows the silyl groups of the treatment agent to bond to the three-dimensional Si-O-Si network formed during the tanning step. This is achieved by forming a new Si-O-Si bond through a condensation reaction between at least one silanol group in the three-dimensional network and at least one silanol group of the silyl-based treatment agent. This Si-O-Si siloxane bond is covalent and is particularly stable and durable over time. In this way, the silyl groups of the treatment agent are incorporated into the Si-O-Si network formed during the tanning step, and are firmly bonded to the collagen of the raw hide and, therefore, to the finished tanned leather. Because the silyl groups of the silyl-based treatment agent are incorporated into the three-dimensional Si-O-Si network bonded to the collagen of the raw hide, the properties imparted to the finished tanned leather by the silyl-based treatment agent are particularly stable. In fact, according to the method of the present invention, the silyl-based treatment agent is bonded to the three-dimensional Si-O-Si network via its silyl functional group, and the silyl functional group is bonded to the three-dimensional Si-O-Si network by a covalent bond, and the three-dimensional Si-O-Si network itself is bonded to the collagen that constitutes the raw hide and, ultimately, the finished tanned leather by a hydrogen bond, an ionic bond or a covalent bond.

[0029] (definition) In this application, the terms have the following meanings:

[0030] "Rawhide" means artificial or animal-derived hides that contain collagen, but that have not undergone the raw hide processing steps described above to prepare them for tanning.

[0031] "Tanned raw hides" means hides that have been subjected to the above-mentioned processing steps of the raw hides, for example pickled or delimed hides, which have also been degreased.

[0032] "Tanned raw hide" or "tanned leather" means raw hide that has undergone at least one tanning step.

[0033] "Finished tanned leather" means raw tanned hides that have undergone at least one refinement step.

[0034] "Alkoxysilane group" is Si-OR 5 means a group, where R 5 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 5 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups.

[0035] "Silanol group" means a Si-OH group, which is generated by hydrolysis of an alkoxysilane group.

[0036] "Silyl group" means an alkoxysilane group, a silanol group, a halosilane, or a silicon polymer. Halosilanes are Si-X, where X is a halogen atom, and Silicon polymers are Si-K, where K is [OSiOsR 6 3-s ] t group, s is an integer from 0 to 3, t is an integer of 1 or greater, and R 6 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 6 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups.

[0037] "Silylation" refers to a grafting reaction between a silylated molecule (i.e., a molecule having an alkoxysilane group on one side and a reactive organic group, such as an isocyanate group, an epoxy group, or an amino group on the other side) and a silylatable molecule (i.e., a molecule or polymer having a silylatable group, i.e., a group reactive with the silylated molecule). Examples of silylated molecules include 3-isocyanatopropyl triethoxysilane (ICPTES), 3-glycidoxypropyl trimethoxysilane (GPTMS), 3-aminopropyl triethoxysilane (APTES), triethoxysilane, and 3-mercaptopropyl trimethoxysilane (MPTES). Silylatable groups include amino groups (-NH2), hydroxyl groups (-OH), carboxyl groups (-COOH), isocyanate groups (NCO), and vinyl groups (-CH=CH2).

[0038] "Silyl-based treating agent" means a treating agent having at least one silyl group.

[0039] A "treating agent" is any compound capable of imparting one or more refined properties to tanned or tanned-prepared raw hides. Advantageously, the compound may be in any form, e.g., a molecule, polymer, material, capable of accepting, by silylation, a silylation molecule containing one or more silyl groups, and preferably comprising at least one silylatable group. Advantageously, a treating agent may be defined as a compound comprising two complementary moieties, one T moiety and the other A moiety, which together constitute a compound of formula TA, where T moiety corresponds to the compound (e.g., molecule, polymer, material, nanoparticle) that provides the treatment function and is free of silylatable groups, and is referred to as the treating group of the treating agent. A moiety corresponds to the silylatable group of the treating agent (e.g., amino, hydroxyl, carboxyl, vinyl). When the treating agent undergoes silylation, A moiety is converted into a linking group W between the treating group T and the silyl group of the silyl-based treating agent. Linking group W may be, for example, [C2] JPEG2025538513000003.jpg23170[3] JPEG2025538513000004.jpg23170[C4] JPEG2025538513000005.jpg24170[5] JPEG2025538513000006.jpg24170[6] JPEG2025538513000007.jpg24170[7] JPEG2025538513000008.jpg20170[8] It may also be selected from JPEG2025538513000009.jpg19170.

[0040] "Enhancing properties" means any properties that are desirable to be imparted to tanned or prepared hides in order to obtain a finished tanned leather that can be used for the possible uses of the tanned leather. Enhancing properties include, but are not limited to, properties that provide the following effects: These include compostable, gas absorbing (e.g. CO2), degradable, ephemeral leather, edible, antibacterial, self-moisturizing, antiseptic, anti-wrinkle, anti-perspirant, shape memory, anti-mold, cooling effect, temperature regulation, foam effect, stain resistant, oil resistant, fresh water resistant, salt water resistant, flame retardant, abrasion resistant, protection against chemicals, protection against Hv, flexibility, elasticity, fat-liquidizing, hardening, fillable, abrasion resistant, anti-static, anti-wrinkle, infrared resistant, anti-slip, feel modifying, photochromic, thermochromic, scent, luminescent, phosphorescent, color, fluorescent, reflective, wet effect, matt effect, gloss effect. Fruit, metallic effect, chemochromic properties, transparent leather, slate effect, medical indicators, active ingredient release, rebound effect, sound insulation, heat storage, inertia, thixotropy, thermal insulation, electricity storage, automatic graining, surface loss, nubuck effect without sanding, quantum dots (semiconductor particles that change color depending on the frequency and size received), traceability markers, expandability, fungus resistance, reconfigurability, adhesive effect, thermoformability, humidity sensor, magnetism, tactile sensation, polymerization precursors, tasteful tanned leather, self-healing, acoustic effects, data storage, GPS (Global Positioning System) location, electrical conductivity.

[0041] Advantageously, the treatment agent that contributes to imparting softness, elasticity and fat-reducing effect is the compound Fatty acids, such as aliphatic or branched carboxylic acids, composed of a chain containing at least four carbon atoms, more or less unsaturated, i.e. with one or more double bonds, preferably consisting of 4 to 36 carbon atoms, for example butyric acid, palmitic acid, arachidic acid Polyethylene glycol with a molar mass between 62 and 20,000 g / mol It may be selected from:

[0042] Advantageously, the treatment agents that contribute to aesthetic effects such as color, luminescence, phosphorescence, fluorescence, matte effect, gloss effect, metallic effect, slate effect, transparency effect, etc., are compounds Coloring agents Fluorescein It may be selected from:

[0043] Advantageously, the treatment agent contributing to the hardening and / or filling properties is a compound ·metal Polyphenols Cellulose derivatives, such as hydroxypropylmethylcellulose It may be selected from: [Brief explanation of the drawings]

[0044] [Figure 1] FIG. 1 is a fluorescence micrograph of the samples in tests B0, B1 and B2 of Example 1. [Figure 2] FIG. 2 is a graph showing the release of fluorescein over time in Example 1 (according to the invention and the comparative example). [Figure 3] FIG. 3 is a photograph of Samples E1 and E0 of Example 2 under an ultraviolet lamp. [Figure 4] FIG. 4 is a graph showing the resistance of fluorescein over time in Example 2 (according to the invention and the comparative example). DETAILED DESCRIPTION OF THE INVENTION

[0045] The raw skins used in the method according to the invention may be any raw skins containing collagen, whether artificial or of animal origin, such as those derived from animals whose skins contain collagen, such as cattle, sheep, goats, reptiles (snakes, lizards, crocodiles, alligators), fish, birds, amphibians, pigs, etc.

[0046] In the first step, step (i) or step (a) of the method according to the invention, rawhide is processed to obtain raw hides ready for tanning.

[0047] The rehydration and degreasing processes are well known to those skilled in the art. For example, to rehydrate and degrease pickled hides, the hides may be placed in a drum and water, salt, and a degreasing agent may be added. The drum is a rotating barrel and is well known to those skilled in the art. The degreasing agent may be selected from nonionic and anionic surfactants in a known manner. For example, the drum may be rotated without heating for a period of 15 minutes to 10 hours, the drum may be drained, and the hides may be washed with salt water at room temperature. In this manner, tanning-ready hides may be obtained.

[0048] In the first method according to the invention, in step (ii), the raw hides prepared for tanning are treated with at least one compound of the following formula (I): [C1] It is tanned using a tanning composition containing the tanning agent JPEG2025538513000010.jpg45170.

[0049] where Y 1 , Y 2 , Y 3 and Y 4 may be the same or different and independently represent a halogen atom, -[OSiO u R 1 3-u ] v group, -O-[SiO u H u-1 R 1 3-u ] v -H group or -OR 2 group, and two or more -[OSiO u R 1 3-u ] v group, -O-[SiO u H u-1 R 1 3-u ] v -H group and -OR 2 The groups may be covalently bonded to one another, where: u is an integer between 0 and 3, v is an integer greater than or equal to 1, and R 1 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 1 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; ·R 2 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 2 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups.

[0050] Preferably, Y 1 , Y 2 , Y 3 and Y 4 may be the same or different and independently represent a halogen atom, —O—[SiO u H u-1 R 1 3-u ] v -H group or -OR 2 Preferably, Y 1 , Y 2 , Y 3 and Y 4 may be the same or different and independently represent a halogen atom or -OR 2 is selected from the group

[0051] For the purposes of this invention, "C1-C 10 An "alkyl" group means a saturated straight or branched chain hydrocarbon containing from 1 to 10 carbon atoms, such as methyl, ethyl, isopropyl, tert-butyl, pentyl, and the like groups.

[0052] By aryl is meant an aromatic group, preferably containing from 5 to 10 carbons, containing one or more rings, and optionally containing heteroatoms such as oxygen, nitrogen or sulfur, among others, such as phenyl, furan, indole, pyridine, naphthalene, etc.

[0053] "C2-C 10 An "alkenyl" group refers to a straight or branched chain hydrocarbon containing at least one unsaturation and containing from 2 to 10 carbon atoms, such as ethenyl (vinyl), propenyl, 2,4-hexadienyl, and the like groups.

[0054] "C2-C 10 An "alkynyl" group refers to a straight or branched chain hydrocarbon containing at least one double unsaturation and containing from 2 to 10 carbon atoms, such as acetylene, propyne, butyne, and the like groups.

[0055] A "polyalkylene oxide" group refers to a polymer of ethylene oxide units, the number of ethylene oxide units being one or greater.

[0056] Derivatives of polyalkylene oxides refer to one or more synthetic polymers selected from the following: copolymers of carboxylic acids and carboxylic acid esters of poly(alkylene glycols), copolymers of carboxylic acids and carboxylic acid esters of poly(alkyleneamide glycols), copolymers of carboxylic acids and poly(alkylene glycol)imides, copolymers of carboxylic acids and poly(alkylene glycol)vinyl ethers, and mixtures thereof, which may or may not be neutralized.

[0057] In one embodiment, Y 1 , Y 2 , Y 3 and Y 4 are independently selected from a chlorine atom, an —OH group or an —OCH2CH3 group.

[0058] The compound of formula (I) may be a precursor to Si(OH) or Si(OH) itself. In one embodiment, the compound of formula (I) is Si(OH). In another embodiment, the compound of formula (I) is Si(OCHCH).

[0059] During the tanning process, the polymerization of Si(OH)4 forms a three-dimensional network of Si-O-Si. This three-dimensional network binds to the collagen that makes up the raw hide, stabilizing it. The tanned raw hide is obtained.

[0060] In addition to the compound of formula (I), the tanning composition generally comprises at least water.

[0061] The tanning composition may also contain salts such as sodium chloride.

[0062] The salt optionally included in the tanning composition serves the function of preventing swelling of raw hides in water. For purposes of the present invention, salt refers to any compound in which an anion and a cation form a neutral product with no total charge. The salt may be selected from potassium chloride, sodium chloride, and mixtures thereof. The need for salt in a tanning composition can be determined by one skilled in the art. This need generally depends on the pH selected for the tanning composition. For example, if the pH of the aqueous solution is less than 5.0, it is preferred that the tanning composition contain a salt. The preparation of such an aqueous salt solution is within the skill of one skilled in the art. The determination of the amount of salt, such as sodium chloride, required to prevent swelling of raw hides is within the skill of one skilled in the art.

[0063] The tanning composition may contain any tanning agent in addition to the compound of formula (I), for example, the tanning composition may contain additional tanning agents selected from chromium, glutaraldehyde, triazine, vegetable tannins such as mimosa, chestnut, quebracho, and mixtures thereof.

[0064] Advantageously, the compound of formula (I) is present in the tanning composition in a weight ratio relative to the raw hides prepared for tanning ranging from 0.1% to 100%, preferably ranging from 5% to 60%, more preferably ranging from 5% to 30%.

[0065] Contact of the raw hides, ready for tanning, with the tanning composition is usually carried out in a drum, the pH of which is adjusted to a desired value, for example, between 1.5 and 10.5, by adding an acid or a base to the composition.

[0066] The drum is then rotated for a period of time until the silicic acid penetrates the hides. This period depends on the thickness and properties of the hides. The duration of this step can be easily determined by one skilled in the art based on the hides being tanned. The rotation of the drum is preferably carried out at room temperature, i.e., below 30°C, preferably in the range of 20 to 25°C. After the silicic acid has penetrated the hides, a neutralization step can be carried out. This can be done, for example, by adjusting the pH of the tanning composition to a value in the range of 2.1 to 10.5, preferably in the range of 4.0 to 8.0.

[0067] At the end of the tanning stage, stabilized raw hides, or tanned raw hides, are obtained, also called tanned leather.

[0068] The method involves using at least one silyl-based treating agent to impart one or more refined properties to the tanned leather.

[0069] According to a first method according to the invention, silyl-based treatment agents are used in the tanning step (ii) and / or in the subsequent refinement step (iii).

[0070] In one embodiment, a silyl-based treating agent is used at least in tanning step (ii), in which case the silyl-based treating agent is generally added to the tanning composition.

[0071] Advantageously, the tanning composition further comprises at least one silyl-based treating agent, said silyl-based treating agent being present in the tanning composition in an amount (by weight relative to the weight of the compound of formula (I)) ranging from 0.1 to 50%, preferably from 0.1 to 35%, more preferably from 0.1 to 10%.

[0072] In the tanning step, the silyl group of the silyl treatment agent bonds to the three-dimensional Si-O-Si network formed by polymerization of Si(OH)4 through a condensation reaction between at least one silanol group in the three-dimensional network and at least one silanol group in the silyl treatment agent. This firmly bonds the silyl treatment agent to the three-dimensional network. It is particularly noteworthy that in the first method according to the present invention, the silyl treatment agent does not constitute a tanning auxiliary during tanning step (ii), and tanning is preferably carried out mainly by polymerization of silicate Si(OH)4.

[0073] During the tanning step, several different silyl-based treatments can be used to impart several enhancing properties to the tanned leather.

[0074] Alternatively or in combination, a silyl treating agent may be used at least in the upgrading step, ie, step (iii) following step (ii).

[0075] During the upgrading step, the silyl group of the silyl-based treatment agent bonds to the three-dimensional Si-O-Si network formed by Si(OH)4 during tanning through a condensation reaction between at least one silanol group in the three-dimensional network and at least one silanol group in the silyl-based treatment agent. This firmly bonds the silyl-based treatment agent to the three-dimensional network, ensuring a strong bond of the silyl group to the inside or surface of the tanned raw hide. Therefore, the properties imparted to the finished tanned leather by the silyl-based treatment agent are particularly stable.

[0076] The upgrading step can be carried out in a dry, ambient, or wet environment. For example, an aqueous solution of a silyl-based treatment agent can be prepared. The tanned raw hides are placed in a drum in an acidic or basic aqueous solution, preferably acidic, e.g., a pH of 1.5 to 2.0, and the aqueous solution of the silyl-based treatment agent is added thereto. The drum is rotated with agitation for a period and under conditions determined by one skilled in the art. The pH of the solution containing the raw hides and silyl-based treatment agent is then adjusted to a range of 3.0 to 10.5, preferably 3.5 to 7.0, and more preferably 4.0 to 5.0. At the end of this process, the drum is emptied, and the treated raw hides may be rinsed.

[0077] Alternatively, the aqueous solution of the silyl-based treatment agent can be deposited on the surface of the tanned raw hides. Polymerization of the silyl-based treatment agent can be achieved, for example, by simply drying the tanned raw hides that have been treated in this way.

[0078] During the refinement step, several different silyl-based treatments can be used simultaneously or sequentially to impart one or more refined properties to the tanned leather.

[0079] Thus, the method according to the invention can include several refinement steps.

[0080] Advantageously, the silyl treating agent is of formula (II) [9] JPEG2025538513000011.jpg40170 compounds are selected.

[0081] where: A 1 and A 2 may be the same or different, and independently of each other, Y 5 or WT. Y 5 is a halogen atom, -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 33-q ] r -H group or -OR 4 group, and two or more -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 3 3-q ] r -H group or -OR 4 The groups may be covalently bonded to one another, where: q is an integer from 0 to 3, r is an integer equal to or greater than 1, and R 3 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 3 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; R 4 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 4 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; p is an integer greater than or equal to 1, W is [Case 2] JPEG2025538513000012.jpg24170[3] JPEG2025538513000013.jpg26170[C4] JPEG2025538513000014.jpg27170[5] JPEG2025538513000015.jpg23170[6] JPEG2025538513000016.jpg22170[7] JPEG2025538513000017.jpg19170[8] JPEG2025538513000018.jpg19170 was selected as the binding group, ·T is the treating group of the treating agent.

[0082] Preferably, Y 5 is a halogen atom, -O-[SiOqH q-1 R 3 3-q ]rH group or -OR 4 Preferably, Y 5 is a halogen atom or -OR 4 It is the base.

[0083] Preferably, the compound of formula (II) is a compound of formula (III) JPEG2025538513000019.jpg42170 or (IV) This does not apply to JPEG2025538513000020.jpg34170, where R is a hydrocarbon group.

[0084] "Hydrocarbon group" means a compound consisting solely of carbon and hydrogen atoms.

[0085] Advantageously, the silyl treating agent is Silylated fluorescein [C10] JPEG2025538513000021.jpg56170 and Silylated hydroxypropyl methylcellulose [C11] JPEG2025538513000022.jpg63170, where x is an integer of 1 or more, y is (1-x), R is -H, -CH3, or m is an integer of 1 or more. [C12] JPEG2025538513000023.jpg20170; and Silylated polyethylene glycol [C13] JPEG2025538513000024.jpg33170, where n is an integer of 1 or more; and and mixtures thereof.

[0086] In a second method according to the present invention, in step (a), tanning and upgrading of tanned-ready raw hides are carried out using a treatment composition comprising at least the silyl-based treatment agent described above. For purposes of this application, "treatment composition" means a composition that allows tanning and upgrading to be carried out in a single step. That is, according to this second method, tanning and upgrading can be carried out in a single step using a single compound, the silyl-based treatment agent. Thus, the treatment composition may not comprise a compound of formula (I).

[0087] During the tanning and upgrading step (b), the polymerization of the silyl-based treatment agent forms a three-dimensional Si-O-Si network. This three-dimensional network binds to the collagen that constitutes the raw hide, stabilizing the raw hide. Furthermore, the treatment groups of the silyl-based treatment agent bond to the three-dimensional Si-O-Si network by covalent bonds. This results in the production of tanned and upgraded, i.e., finished, tanned leather.

[0088] In addition to the silyl-based treating agent, the treating composition generally includes at least water.

[0089] The treatment composition may contain salts to prevent the raw hide from swelling in water, as previously mentioned. The treatment composition may contain any tanning agent, such as an additional tanning agent selected from chromium, glutaraldehyde, triazine, vegetable tannins such as mimosa, chestnut, quebracho, and mixtures thereof.

[0090] Advantageously, the pH of the treatment composition is in the range of 1.0 to 10, preferably in the range of 1.5 to 4.0, preferably in the range of 1.6 to 2.0.

[0091] Advantageously, the silyl-based treatment agent is present in the treatment composition in a mass ratio relative to the tanning-ready raw hides in the range of from 1 to 100%, preferably in the range of from 1 to 5%, more preferably in the range of from 1 to 20%.

[0092] Advantageously, the silyl treating agent is a compound of formula (II) [9] Selected from JPEG2025538513000025.jpg40170, where: A 1 and A 2 may be the same or different, and independently of each other, Y 5 or WT. Y 5 is a halogen atom, -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 3 3-q ]rH group or -OR 4 group, and two or more -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 3 3-q ]rH group or -OR 4 The groups may be covalently bonded to one another, where: q is an integer from 0 to 3, r is an integer equal to or greater than 1, and R 3 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 3 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; R 4 is a hydrogen atom, C1-C 10 Alkyl groups, aryl groups, C2-C 10 Alkenyl groups, C2-C 10R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 4 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; p is an integer greater than or equal to 1, W is [C2] JPEG2025538513000026.jpg24170[3] JPEG2025538513000027.jpg26170[C4] JPEG2025538513000028.jpg27170[5] JPEG2025538513000029.jpg23170[6] JPEG2025538513000030.jpg22170[7] JPEG2025538513000031.jpg19170[8] JPEG2025538513000032.jpg19170 was selected as the binding group, ·T is the treating group of the treating agent.

[0093] Preferably, Y 5 is a halogen atom, -O-[SiOqH q-1 R 3 3-q ]rH group or -OR 4 Preferably, Y 5 is a halogen atom or -OR 4 It is the base.

[0094] Preferably, the compound of formula (II) is (III) JPEG2025538513000033.jpg42170 or formula (IV) This does not apply to JPEG2025538513000034.jpg34170, where R is a hydrocarbon group.

[0095] "Hydrocarbon group" means a compound consisting solely of carbon and hydrogen atoms.

[0096] According to a second method according to the invention, the finished tanned leather obtained at the end of tanning and refining step (b) may be subjected to further refining steps subsequent to step (b), in which the same silyl-based treating agent as used in tanning and refining step (b) may be used or other silyl-based treating agents may be used.

[0097] The method according to the invention is particularly easy to carry out and can impart one or more refinement properties to suitably tanned raw hides. Furthermore, the method according to the invention allows several refinement properties to be achieved in one refinement step and / or in one tanning / refining step.

[0098] The present invention also relates to a method for de-glazing finished tanned leather according to the invention, said method comprising at least one step of immersing the finished tanned leather in a basic solution to bring the pH of the tanned leather to a value above 10.5, preferably in the range from 11.5 to 13.0.

[0099] For example, to perform de-luxurization, the finished tanned leather is immersed in an aqueous solution, for example in a drum. The aqueous solution may contain a degreasing agent. The degreasing agent may be selected from surfactants, for example nonionic or anionic surfactants. The purpose of such a step is to degrease and rehydrate the tanned leather. The drum is then emptied and the tanned leather may be rinsed in the drum at room temperature.

[0100] The tanned leather is immersed in an aqueous solution containing a basifying agent to adjust the pH of the raw hide and / or tanned leather to a value of 10.5 or higher, preferably in the range of 11.5 to 13.0.

[0101] The basifying agent may be selected from, for example, sodium bicarbonate, sodium carbonate, ammonia, sodium hydroxide, and mixtures thereof.

[0102] Raising the pH of the finished tanned leather above 10.5, preferably between 11.5 and 13.0, results in the destruction of the three-dimensional Si-O-Si network that was bound to the collagen of the raw hide, and therefore the silylating agent is removed from the tanned leather, and the tanned leather no longer possesses the properties previously imparted by the silylating agent.

[0103] The present invention will be better understood from the following experimental section and the accompanying drawings.

[0104] --Experiment Department-- (Example 1) Production of finished tanned leather with fluorescent properties using silyl-based treatment agents during the tanning step (a) Preparation of Si(OH)4 from Si(OCH2CH3)4 Mix 1 L of Si(OCH2CH3)4 with 1 L of water.

[0105] The pH of the mixture is adjusted to a value in the range of 1.5 to 2.0 using a strong acid, such as, but not limited to, hydrochloric acid or sulfuric acid.

[0106] The hydrolysis reaction of Si(OCH2CH3)4 to Si(OH)4 is exothermic. Therefore, it is recommended to maintain the temperature of the mixture at a desired value, for example, around 30°C, using a cooling bath. Preferably, the mixture is vigorously stirred for 15 to 120 minutes. The hydrolysis reaction lasts for 20 minutes to 2 hours. Upon completion of the reaction, a clear solution of silicic acid with the chemical formula Si(OH)4 is obtained. 10% by mass of sodium chloride was added to the total mass of the silicic acid solution prepared earlier.

[0107] (b) Manufacture of finished tanned leather Test B1: Add 0.25 mol % of silylated fluorescein relative to the number of moles of Si(OH)4.

[0108] (i) Manufacture of raw hides and skins ready for tanning The lambskins are obtained as pickled or demineralized hides from storage. These hides are degreased and rehydrated in preparation for tanning according to the expertise of a person skilled in the art. The hides are weighed.

[0109] (ii) Tanning The raw hides are placed in a drum in a salt solution, and the pH of the raw hides and the aqueous solution is adjusted to a value between 1.5 and 2.0.

[0110] Dissolve silylated fluorescein powder (prepared in the laboratory) in an acidic aqueous solution (pH between 1.5 and 2.0) to prepare a silylated fluorescein solution with a mass concentration of 25 g / L.

[0111] The silylated fluorescein used has the formula: [C10] JPEG2025538513000035.jpg41170

[0112] The following are added to the drum in relative weight to the raw hides: Cold water (25°C), 50% Sodium chloride, 5% Si(OH)4 hydrolyzed from Si(OCH2CH3)4 as described in (a), 13%.

[0113] Additionally, 1.56% of silylated fluorescein is added relative to the mass of Si(OH)4, which represents a molar amount of 0.25% relative to the number of moles of Si(OH)4 or a relative mass of 0.20% relative to the mass of raw hides.

[0114] The drum is rotated for 4 hours at room temperature, ie, 25°C.

[0115] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated for 1 hour. The final pH of the solution is in the range of 3.8 to 4.0.

[0116] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated overnight. The final pH of the solution is in the range of 4.0 to 4.5.

[0117] The drum is then drained and the raw hides are rinsed, resulting in tanned raw hides with fluorescent properties.

[0118] Test B2: Add 0.03 mol % of silylated fluorescein relative to the number of moles of Si(OH)4.

[0119] This test is carried out by the same procedure as test B1, except that 0.03 mol % of silylated fluorescein relative to the number of moles of Si(OH)4 is used instead of 0.25 mol % of silylated fluorescein relative to the number of moles of Si(OH)4.

[0120] Test B0: No silylated fluorescein added.

[0121] This test is carried out according to the same procedure as test B1, but without the addition of silylated fluorescein.

[0122] Test B1bis: Addition of 0.25 mol % of unsilylated fluorescein to the moles of Si(OH)4. This test serves as a negative control to demonstrate that the silylated fluorescein is covalently bound to the Si-O-Si network.

[0123] This test is carried out according to the same procedure as test B1, except that 0.25 mol % of silylated fluorescein relative to the number of moles of Si(OH)4 is replaced by 0.25 mol % of non-silylated fluorescein relative to the number of moles of Si(OH)4.

[0124] (c) Control of the fluorescence properties of tanned leather finished in (b) For each of the tests B0, B1 and B2, a sample of the tanned raw hide, which has been tanned, rinsed and is still wet, is cut from the neck area measuring approximately 2 cm x 1 cm.

[0125] The samples are analyzed using a fluorescence microscope (Leica THUNDER Imager Model Organism).

[0126] The results obtained are shown in Figure 1. The image labeled B1 shows the fluorescence obtained in test B1. The image labeled B2 shows the fluorescence obtained in test B2. The image labeled B01 shows the fluorescence obtained in test B0.

[0127] (d) Demonstration of the stability of the obtained properties For each of the tests B1 and B1bis, tanned, rinsed, and wet samples (1.76 g) of raw hide were cut from the neck, measuring approximately 2 cm x 0.5 cm. The samples were placed in two separate tubes, and 10 mL of saline solution (10% NaCl by weight relative to water) was added. The tubes were then vortexed. At various times, 10 mL of the solution was withdrawn for analysis at 495 nm using a UV spectrometer (Agilent Technologies, Cary 60 UV-Vis), and the tanned leather samples were placed in a new saltwater bath. This procedure was repeated until fluorescein release stabilized.

[0128] The results are shown in Figure 2. Using a calibration curve relating the molar concentration of fluorescein to its UV absorbance at 495 nm, the amounts of silylated fluorescein (B1) and non-silylated fluorescein (B1bis) in the sample can be calculated. In other words, the release of fluorescein from the tanned leather can be monitored over time. The curve shows that non-silylated fluorescein (B1bis), which is not bound to the tanned Si-O-Si network, is released in large amounts over time. In contrast, silylated fluorescein (B1), which is covalently bound to the Si-O-Si network, is released in very small amounts over the same period.

[0129] Thus, in this example, a finished tanned leather with fluorescent properties was obtained by using a silyl-based treating agent during the tanning step. In this example, the compound of formula (I) is Si(OH)4, and the compound of formula (II) is a silylated fluorescein. Thus, the compounds of formula (I) and (II) are added during the tanning step. Tanning and upgrading are carried out simultaneously. This method is quick and easy to carry out.

[0130] (Example 2) Production of finished tanned leather with fluorescent properties using silyl-based treatment agents during the upgrading step after tanning (a) Manufacture of finished tanned leather In this example, Si(OH)4 is prepared as in Example 1(a).

[0131] (i) Manufacture of raw hides and skins ready for tanning The lambskins are obtained as pickled or demineralized hides from storage. These hides are degreased and rehydrated in preparation for tanning according to the expertise of a person skilled in the art. The hides are weighed.

[0132] (ii) Tanning The raw hides are placed in a drum in a salt solution, and the pH of the raw hides and the aqueous solution is adjusted to a value between 1.5 and 2.0.

[0133] The following are added to the drum in relative weight to the raw hides: Cold water (25°C), 50% Sodium chloride, 5% Si(OH)4 hydrolyzed from Si(OCH2CH3)4 as described in Example 1(a), 13%

[0134] The drum is rotated for 4 hours at room temperature (25°C).

[0135] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated for 1 hour. The final pH of the solution is in the range of 3.8 to 4.0.

[0136] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated overnight. The final pH of the solution is in the range of 4.0 to 4.5.

[0137] The drum is then emptied and the tanned raw hides are rinsed and then dried.

[0138] (iii) Upgrade step Dissolve silylated fluorescein powder (prepared in the laboratory) in an acidic aqueous solution (pH between 1.5 and 2.0) to prepare a silylated fluorescein solution with a mass concentration of 25 g / L.

[0139] The silylated fluorescein used has the formula: [C10] JPEG2025538513000036.jpg43170

[0140] The silylated fluorescein solution was taken in a syringe and dropped onto the surface of the raw hide tanned in step (ii). The grafting reaction of the silylated fluorescein onto the three-dimensional Si-O-Si network formed by tanning with Si(OH)4 in step (ii) was carried out by drying.

[0141] The finished tanned leather is then dried in air for two hours, resulting in a finished tanned leather with fluorescent properties.

[0142] (b) Control of the resistance to washing of the characteristic imparted to tanned leather The areas where the silylated fluorescein was applied can be identified by yellow marks in the finished tanned leather.

[0143] To demonstrate the stability of the given fluorescence properties, two samples of finished tanned leather were prepared from the finished tanned leather of step (iii): one test, hereafter referred to as E1, and one control, hereafter referred to as E0.

[0144] Sample E1 is placed in an aqueous solution (pH 7) for 2 weeks. Sample E0 is kept as a non-immersed control.

[0145] After two weeks, E1 and E0 are analyzed under a 366 nm ultraviolet (UV) lamp, and Figure 3 is a photograph of what is observed under this lamp.

[0146] The area marked E1 corresponds to the test sample E1, and the area marked E0 corresponds to the control sample E0. No difference was observed between the immersed sample E1 and the non-immersed control sample E0. This test shows that the properties imparted by the refinement of tanned leather, i.e., the fluorescent properties, can withstand washing in water for at least two weeks. Therefore, the refinement properties imparted to tanned leather by silylated fluorescein are stable over time.

[0147] (c) Demonstration of the durability of the obtained properties Test E1bis: Fluorescein enhancement without silylation This test E1bis serves as a negative control to demonstrate that the silylated fluorescein is covalently bound to the Si-O-Si network.

[0148] This test E1bis is carried out according to the same procedure as test E1, but using non-silylated fluorescein instead of silylated fluorescein in the modification step.

[0149] More specifically, at the end of step (ii) above, a sample P of tanned raw hides is selected.

[0150] During the refinement step, solutions of silylated fluorescein and non-silylated fluorescein were successively taken up in syringes and dripped onto the surface of the tanned raw leather sample P. The dripping formed a C shape. The upper half of the C was formed by non-silylated fluorescein (Test E1bis), and the lower half of the C was formed by silylated fluorescein (Test E1). The grafting reaction of the silylated fluorescein onto the three-dimensional Si-O-Si network formed by tanning with Si(OH)4 in step (ii) was carried out by drying. The non-silylated fluorescein did not graft or react, but simply dried on the surface of the tanned leather.

[0151] The tanned leathers enriched with unsilylated fluorescein (Test E1bis) and with silylated fluorescein (Test E1) were left to dry in air for 2 hours. The areas where unsilylated fluorescein and silylated fluorescein had been applied can be identified by yellow marks in the finished tanned leather.

[0152] To demonstrate that the silylated fluorescein was covalently grafted, and in contrast to the non-silylated fluorescein, samples of tanned raw hide P were immersed in salt water (10% NaCl by weight relative to water) and analyzed under a 366 nm ultraviolet (UV) lamp at various times.

[0153] Figure 4 shows the images observed under this lamp at various times, i.e., t = 0 h, t = 7 h, t = 24 h, and t = 120 h. The area labeled E1 corresponds to silylated fluorescein, and the area labeled E1bis corresponds to fluorescein without silylation. The image corresponding to fluorescein without silylation fades over time and is no longer visible after 120 h. In contrast, the image corresponding to silylated fluorescein does not fade and is stable over time.

[0154] This test demonstrated the advantage of using silylated fluorescein covalently grafted onto tanned leather. This covalent grafting allows the enhancement, i.e., fluorescent properties, to be retained for a much longer period than when non-silylated fluorescein is used, which is not covalently grafted onto tanned leather. Thus, the enhancement imparted to tanned leather by silylated fluorescein is stable over time.

[0155] (Example 3) Production of nourished, finished tanned leather using silyl-based treatment agents during the tanning step In this example, Si(OH)4 is prepared as in Example 1(a).

[0156] (i) Manufacture of raw hides and skins ready for tanning The lambskins are obtained as pickled or demineralized hides from storage. These hides are degreased and rehydrated in preparation for tanning according to the expertise of a person skilled in the art. The hides are weighed.

[0157] (ii) Tanning The raw hides are placed in a drum in a salt solution, and the pH of the raw hides and the aqueous solution is adjusted to a value between 1.5 and 2.0.

[0158] Dissolve monosilylated PEG powder (prepared in the laboratory) in an acidic aqueous solution (pH between 1.5 and 2.0) to prepare a monosilylated PEG solution with a mass concentration of 25 g / L.

[0159] The following are added to the drum in relative weight to the raw hides: Cold water (25°C), 50% Sodium chloride, 5% Si(OH)4 hydrolyzed from Si(OCH2CH3)4 as described in Example 1(a), 13%

[0160] A 10% solution of monosilylated polyethylene glycol (PEG) was further added in a relative amount to the mass of Si(OH)4, which corresponds to 0.18 mol% of the moles of Si(OH)4 or 1.3% of the mass of the raw hides.

[0161] The monosilylated PEG used has the formula: [C13] JPEG2025538513000037.jpg33170Here, n is an integer greater than or equal to 1.

[0162] The drum is rotated for 4 hours at room temperature, ie, 25°C.

[0163] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated for 1 hour. The final pH of the solution is in the range of 3.8 to 4.0.

[0164] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated overnight. The final pH of the solution is in the range of 4.0 to 4.5.

[0165] The drum is then emptied and the raw hides are rinsed.

[0166] The result is a nourished, finished tanned leather.

[0167] (Example 4) Production of finished tanned leather that has been treated with a silyl-based treatment during the post-tanning refinement step In this example, Si(OH)4 is prepared as in Example 1(a).

[0168] (i) Manufacture of raw hides and skins ready for tanning The lambskins are obtained as pickled or demineralized hides from storage. These hides are degreased and rehydrated in preparation for tanning according to the expertise of a person skilled in the art. The hides are weighed.

[0169] (ii) Tanning The raw hides are placed in a drum in a salt solution, and the pH of the raw hides and the aqueous solution is adjusted to a value between 1.5 and 2.0.

[0170] The following are added to the drum in relative weight to the raw hides: Cold water (25°C), 50% Sodium chloride, 5% Si(OH)4 hydrolyzed from Si(OCH2CH3)4 as described in Example 1(a), 13%

[0171] The drum is rotated for 4 hours at room temperature (25°C).

[0172] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated for 1 hour. The final pH of the solution is in the range of 3.8 to 4.0.

[0173] Then, 5% by weight of sodium formate based on the weight of the raw hides is added to the drum at 25°C. The drum is rotated overnight. The final pH of the solution is in the range of 4.0 to 4.5.

[0174] The drum is emptied and the tanned raw hides are rinsed.

[0175] (iii) Upgrade step The tanned raw hides from step (ii) are placed in a drum. 500% water is added relative to the weight of the raw hides. 2% sodium bicarbonate is added relative to the weight of the raw hides to equalize the pH of the raw hides to a value in the range of 5.0 to 8.0, preferably 6.0 to 7.5.

[0176] The drum is rotated for approximately 40 minutes, after which it is emptied.

[0177] Dissolve silylated hydroxypropyl methylcellulose powder (HPMC, prepared in the laboratory) in an aqueous solution (pH between 6.0 and 8.0) to prepare a silylated HPMC solution with a mass concentration of 12.5 g / L.

[0178] Silylated hydroxypropyl methylcellulose has the following chemical formula: [C11] JPEG2025538513000038.jpg63170

[0179] where x is an integer greater than or equal to 1, y is equal to (1-x), and R is -H, -CH3, or has the formula: [C12] JPEG2025538513000039.jpg17170Here, m is an integer greater than or equal to 1.

[0180] After dissolution, the mixture is added to the drum containing the tanned raw hides. The drum is rotated and the temperature is brought to 50°C. Agitation is carried out for 2 hours, after which formic acid (3% by weight relative to the weight of the raw hides) is added to fix the HPMC (hydrolysis and condensation of the siloxane groups at an acidic pH). A pH of 3.0 to 4.5 is obtained. The drum is agitated for 1 hour, then emptied and the tanned and nourished raw hides are rinsed.

[0181] This results in finished, trimmed tanned leather.

Claims

1. Finished tanned leather having at least one refined property imparted by at least one silyl-based treatment agent, The silyl-based treating agent is covalently bonded to a three-dimensional Si-O-Si network, Finished tanned leather, wherein the three-dimensional Si-O-Si network is bonded to the collagen constituting the finished tanned leather by hydrogen bonds, ionic bonds or covalent bonds.

2. A method for producing the finished tanned leather of claim 1 from rawhide, comprising at least (i) processing raw hides to obtain raw hides ready for tanning; (ii) at least one compound represented by formula (I) [Chemical formula 1] tanning the raw hides of step (i) using a tanning composition containing the tanning agent; Equipped with where Y 1 , Y 2 , Y 3 and Y 4 may be the same or different and independently represent a halogen atom, -[OSiO u R 1 3-u ] v group, -O-[SiO u H u-1 R 1 3-u ] v -H group or -OR 2 group, and two or more -[OSiO u R 1 3-u ] v group, -O-[SiO u H u-1 R 1 3-u ] v -H group and -OR 2 The groups may be covalently bonded to one another; where: u is an integer between 0 and 3, v is an integer greater than or equal to 1, and R 1 is a hydrogen atom, C 1 -C 10 Alkyl group, aryl group, C 2 -C 10 Alkenyl group, C 2 -C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 1 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; ・R 2 is a hydrogen atom, C 1 -C 10 Alkyl group, aryl group, C 2 -C 10 Alkenyl group, C 2 -C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 2 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; The method is characterized in that at least one silyl-based treating agent is used in the tanning step (ii) and / or in the upgrading step (iii) following the tanning step (ii).

3. 3. The method of claim 2, wherein at least one said silyl-based treating agent is used at least during the tanning step (ii).

4. 4. The method of claim 3, 1. A method according to claim 1, wherein the tanning composition comprises the at least one silyl-based treating agent, the silyl-based treating agent being present in the tanning composition in an amount ranging from 0.1 to 50%, preferably from 0.1 to 35%, preferably from 0.1 to 25%, more preferably from 0.1 to 10%, by weight relative to the weight of the compound of formula (I).

5. The method according to any one of claims 2 to 4, 3. A method according to claim 1, wherein said at least one silyl-based treating agent is used at least in step (iii) of post-tanning upgrading.

6. A method for producing finished tanned leather according to any one of claims 2 to 5, Y 1 , Y 2 , Y 3 and Y 4 are each independently a chlorine atom, an -OH group or an -OCH 2 CH 3 The method of claim 1, wherein the compound is selected from the group consisting of:

7. 7. The method of claim 6, wherein the compound of formula (I) is Si(OH) 4 The method according to claim 1, wherein

8. 7. The method of claim 6, wherein the compound of formula (I) is Si(OCH 2 CH 3 ) 4 The method according to claim 1, wherein

9. The method according to any one of claims 2 to 8, A method characterized in that the compound of formula (I) is present in the tanning composition in an amount of 0.1 to 100%, preferably 5 to 60%, more preferably 5 to 30%, by weight relative to the weight of the raw hides prepared for tanning.

10. The method according to any one of claims 2 to 9, The at least one silyl treating agent is represented by formula (II) [Chem.9] is selected from the compounds where: ・A 1 and A 2 may be the same or different, and independently of each other, Y 5 or WT, ・Y 5 is a halogen atom, -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 3 3-q ] r -H group or -OR 4 group, and two or more -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 3 3-q ] r -H group or -OR 4 The groups may be covalently bonded to one another, where: q is an integer from 0 to 3, r is an integer equal to or greater than 1, and R 3 is a hydrogen atom, C 1 -C 10 Alkyl group, aryl group, C 2 -C 10 Alkenyl group, C 2 -C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 3 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; R 4 is a hydrogen atom, C 1 -C 10 Alkyl group, aryl group, C 2 -C 10 Alkenyl group, C 2 -C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 4 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; p is an integer from 0 to 2, B is selected as a heteroatom or one or more R5; ・W is [Case 2] [Chemical 3] [C4] [C5] [Case 6] [C7] [Chem.8] is selected as a linking group from T is the treating group of the treating agent A method characterized by:

11. The method according to any one of claims 2 to 9, The silyl-based treating agent is ・Silylated fluorescein [Chemical formula 10] and, ・Silylated hydroxypropyl methylcellulose [Chemical formula 11] where x is an integer greater than or equal to 1, y is equal to (1-x), and R is -H, -CH 3 , or m is an integer of 1 or more [Chemical formula 12] a silylated hydroxypropyl methylcellulose selected from ・Silylated polyethylene glycol [Chem.13] wherein n is an integer of 1 or greater; and A mixture of these, The method of claim 1, wherein the compound is selected from the group consisting of:

12. A method for producing the finished tanned leather of claim 1 from rawhide, comprising at least (a) processing raw hides to obtain raw hides ready for tanning; (b) tanning and upgrading the raw hides of step (a) using a treatment composition containing at least the silyl-based treatment agent; A method comprising:

13. 13. The method of claim 12, The silyl-based treating agent is represented by the formula (II) [Chem.9] is selected from the compounds where: ・A 1 and A 2 may be the same or different, and independently of each other, Y 5 or WT, ・Y 5 is a halogen atom, -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 3 3-q ] r -H group or -OR 4 group, and two or more -[OSiOqR 3 3-q ] r group, -O-[SiOqH q-1 R 3 3-q ] r -H group or -OR 4 The groups may be covalently bonded to one another, where: q is an integer from 0 to 3, r is an integer equal to or greater than 1, and R 3 is a hydrogen atom, C 1 -C 10 Alkyl group, aryl group, C 2 -C 10 Alkenyl group, C 2 -C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 3 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; R 4 is a hydrogen atom, C 1 -C 10 Alkyl group, aryl group, C 2 -C 10 Alkenyl group, C 2 -C 10 R is selected from an alkynyl group, a polyalkylene oxide group, or a derivative thereof; 4 may optionally contain one or more amine, ammonium, amide, ketone, ester, aldehyde, thiol, or thioether groups; p is an integer equal to or greater than 1, ・W is [Case 2] [Chemical 3] [C4] [C5] [Case 6] [C7] [Chem.8] is selected as a linking group from T is the treating group of the treating agent; A method characterized by:

14. Finished tanned leather having at least one refined property obtainable by the method according to any one of claims 2 to 11 or by the method according to any one of claims 12 to 13.

15. A method for de-luxuring finished tanned leather according to claim 1 or 14, or finished tanned leather obtained by the method according to any one of claims 2 to 11, or the method according to any one of claims 12 to 13, comprising: A method comprising at least the step of immersing the finished tanned leather in a basic solution to bring the pH of the tanned leather to a value above 10.5, preferably in the range of 11.5 to 13.0.

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