276 results about "Leather tanning" patented technology

The invention discloses a method for recovering collagen and chromium salts from chromium-containing scrap leather residues, which comprises the following steps: carrying out alkaline hydrolysis on chromium-containing scrap leather residues with strong alkali assisted by metal oxide and surfactant, recovering collagen from the filtrate, hydrolyzing the filter residues with strong acid, and sequentially carry out redox reaction to obtain a chrome tanning solution or drying to obtain a powdery chrome tanning agent. The invention has the advantages of fewer steps, short period, high efficiency and low production cost, is simple to operate, and can implement effective separation of chromium and hydrolyzed collagen; the recovered industrial collagen has low chromium content and high added value, and thus, can be used as a raw material for producing other fine industrial chemicals; the recovered chromium salts are free of calcium salts, and thus, can be used as a tanning agent for leather tanning again; and the invention does not generate tailings or wastewater, thereby avoiding secondary pollution.

The clear production method for Cr-free vehicle seat cushion comprises: hair-saving, combing acid and base for expansion; ammonia-free deliming, dipping weak acid and low slat, Cr-free bating, composite batting, and adding strong-absorption fat for dyeing to treat skin from pig, cattle or sheep. The product has shrinkage temperature up to 110Deg, shows well hand feeling and resistance to thermal and age. This invention reduces material quantity and 30-50% sewage discharge, improves absorption rate, and brings a new way for Cr-free leather.

The invention provides a non-chromium leather tanning method. The non-chromium leather tanning method comprises the following steps of: (a) pre-treating animal skin, soaking in water and weighing, and soaking in gangue to obtain gangue skin; (b) carrying out deliming, softening and primary pickling onto the raw gangue skin to obtain raw skin; (c) carrying out secondary pickling onto the raw skin; (d) tanning the raw skin after the secondary pickling; (e) primarily fixing the tanned raw skin in formic acid for 30 minutes after carrying out oxidizing, aldehyde-removing and re-tanning; and carrying out neutralizing treatment after rinsing for 60 minutes by virtue of oxalic acid; and (f) getting out the raw skin after the neutralizing treatment from a rotary drum after carrying out fat liquoring, secondary fixing, and water-washing, drying the raw skin after primary stabbing, re-moistening for 20 hours, knocking and softening for 8 hours, and carrying out secondary stabbing and drying to obtain the tanned leather. The leather tanning method provided by the invention is free of chromium-containing preparation, so that the leather processing process is more environment-friendly, and the harms to the construction staffs are reduced.

The invention relates to a preparation method of a chitosan modified graphite oxide functional leather tanning agent. Currently, the common leather tanning agents are chroming tanning agent, aluminum tanning agent, vegetable tanning agent, aldehyde tanning agent and synthetic tanning agent and the like, but the leather tanning agents can generate pollution problems hard to treat. The preparation method provided by the invention has the following steps of: mixing crystalline flake graphite powder, sodium nitrate and concentrated sulfuric acid and stirring uniformly, slowly adding potassium permanganate for oxygenation, and preparing a suspending liquid through washing, pH adjustment and ultrasonic treatment; and degrading chitosan with high-temperature alpha-amylase so as to obtain a degraded chitosan solution, modifying graphite oxide with the degraded chitosan under a horseradish peroxidase-hydrogen peroxide catalysis system, thus obtaining the chitosan modified graphite oxide functional leather tanning agent. The preparation method provided by the invention has the advantages of unique synthetizing preparation process and good tanning property, is suitable for main tanning and retanning; and the leather has excellent intensity and flexibility after main tanning.

The invention provides a melamine-modified waterborne polyurethane flame-retarded resin. The melamine-modified waterborne polyurethane flame-retarded resin is prepared by virtue of chemical reaction of polyisocyanate, polyhydric alcohol, polybasic amine chain extender, low-polymer polyhydric alcohol, dimethylolpropionic acid, melamine, a neutralizer and de-ionized water. The invention also provides a preparation method of the melamine-modified waterborne polyurethane flame-retarded resin. The melamine-modified waterborne polyurethane flame-retarded resin has the characteristics of excellent fire retardance, favorable adhesion, color retention, corrosion resistance, water resistance, alkali resistance, abrasion resistance and the like, is extremely low in VOC and environmentally friendly, can be used for waterborne fire-retardant paint, waterborne flame-retardant paint, waterborne anticorrosion paint, waterborne waterproof and moisture-proof paint, waterborne engineering special paint, waterborne woodware paint and the like, and can be used for leather tanning agents, adhesive agents for synthesizing fireproof laminates, concrete waterproof agents and the like.

The invention is water-soluble self-emulsifying coupled modified silicone oil composite and an application in pickling, tanning and dyeing of leather, which is characterized in that the water-soluble self-emulsifying coupled silicone oil composite after modification is adopted to carry out oil pretanning, tanning, softening, dyeing and setting treatment on pickled skins of animals in a revolving drum. The crust leather to be coated has the advantages of plumpness, softness, no loose grain, good elasticity, good foaming sense and velvet silicon sense after treatment. By adopting the composite and the application method thereof to carry out oil pretanning, tanning, softening, dyeing and setting treatment, the quality of finished leather can be improved and stabilized, the production cost isreduced, the workshop sections such as wet blue pickling and degreasing, chrome retanning, alkali extraction overnight, neutralization and the like in the traditional leather making technique can be completely canceled, and the usage amounts of dye, fatliquor, stuffing and the like can be reduced, water washing is avoided by twice, thus saving more than 40% of water, shortening more than one third of the production period, reducing more than half of subsequent milling time, greatly stabilizing and simplifying the technique procedures, being easy to control the leather quality, and obviously reducing pollutant discharge in the traditional leather-making workshop sections of tanning, pretanning and dyeing water yard and lowering energy consumption such as water, electricity, manpower and the like.

The invention relates to a method for preparing an acrylic resin modified graphene oxide leather tanning agent. Pollution becomes a main problem that hampers the sustainable development of leather industry, wherein a chrome tanning agent is one of leading pollution sources. The method comprises the following steps of: adding concentrated sulfuric acid into a mixture of graphite powder and sodium nitrate, adding potassium permanganate, raising the temperature, reducing the temperature, washing, and dispersing by using ultrasonic waves to obtain an aqueous solution of graphene oxide; and adding methacrylic acid and acrylic acid into the aqueous solution of graphene oxide, treating by using ultrasonic waves, heating, dripping an initiator solution, keeping the temperature, reacting, and controlling the solid content to be 15 percent to obtain a product. The leather tanning agent can be used as a main tanning agent and is used for tanning leather; the tensile strength, the tearing strength and the breaking elongation of the tanned leather are equivalent to those of chrome tanned leather, and the tanned leather has soft and smooth handfeel; the leather tanning agent can substitute pollutional tanning agents such as a chrome tanning agent, an aldehyde tanning agent and the like, so that the pollution of the chrome tanning agent is reduced or eliminated from the source; and the leather tanning agent has a good application prospect.

The invention discloses a method for preparing a modified starch tanning agent, comprising the following steps of: firstly, degrading corn starch; in the presence of HRP (Horse Radish Peroxidase) / hydrogen peroxide (H2O2), grafting and modifying the degraded starch with sulfanilic acid, gallic acid and nekal; and then oxidizing the grafted starch with periodic acid. The invention has the innovation points that a nekal structure unit is introduced in the starch structure so as to improve the permeation wetting function of the modified starch tanning agent; the gallic acid structure unit is introduced to improve the tanning properties of the modified starch tanning agent, the sulfanilic acid is introduced to increase the dispersivity of the modified starch tanning agent, and dialdehyde action is used for improving the tanning properties of the modified starch tanning agent. The preparation method of the invention is peculiar and practical, and the obtained tanning agent is an environmentally-friendly leather tanning agent and is suitable for primary tanning and retanning. The shrinkage temperature (Ts) of pickled leather after primary tanning can be improved to 75-80 DEG C; and the retanned product has the advantages of wash resistance, high absorption rate on dyes and fatting agents and the like, is soft and plump.

The invention relates to a preparation method for a leather tanning agent, in particular to a preparation method for a leather tanning agent with function of strengthening and toughening collagenous fibers. The leather tanning process is a qualitative change process converting raw hide into leather, and can endow the leather with good heat and humidity resistant stability, flexibility and physical and mechanical properties; however, a chrome tanning agent commonly adopted has serious harm to the environment, while a conventional non-chrome tanning agent is hard to meet the requirement on good service performance of the leather. The preparation method takes montmorillonite and acrylic monomers as raw materials, and adopts a monomer in-situ intercalation polymerization method to synthesize the toughening type leather tanning agent; and the toughening type leather tanning agent is used for tanning the leather, can greatly improve the strength and toughness of crust leather, and can reduce the dosage of the chrome tanning agent by 75 percent.

The invention discloses an animal hide fiber loosening method based on the xylanase effect and relates to the field of production of leather and fur leather. The method is characterized in that xylanase is added as a hide fiber loosening additive during the steps such as water soaking, depilation, softening and pickling of leather making or during the steps such as water soaking, softening and pickling of fur leather making. By means of the method, the components such as proteoglycan and glycosaminoglycan, which have a cohesive effect on hide fiber, in the animal hide can be efficiently and specifically destroyed. Hide protein ingredients cannot be destructed. The method has wide applicability and is suitable for the manufacturing process of all-purpose leather or fur leather with various kinds of animal hides as raw materials. The effects of promoting loosening of hide fiber and improving the softness, hand feeling and physical and mechanical properties of finished leather products are achieved. Through the method in the leather making process, pollutants such as lime and sodium sulfide are reduced, and the depilation effect is improved.

The invention discloses a method for tanning leather without pickling. The method is characterized by comprising the following steps (A) deliming: deliming limed hide-cut naked hide in the presence of an ammonium-free deliming agent, wherein the using amount of the ammonium-free deliming agent is 0.8-3 percent of the hide weight; (B) softening: softening in the presence of a softening enzyme, wherein the using amount of the softening enzyme is 0.3-1.5 percent of the hide weight; (C) chrome tanning: performing chrome tanning treatment on the softened naked hide in the presence of a non-prickled chrome tanning agent, wherein the pH value at the initial stage of tanning treatment is 6.5-8.5, the liquid ratio at the initial stage of tanning treatment is 30-50%, and the non-prickled chrome tanning agent is an anionic chrome tanning agent; and (D) finishing: performing post-finishing on tanned blue wet leather to obtain finished leather. By applying the non-pickling chrome tanning method, the emission of salt in leather making, pickling and chrome tanning waste water is avoided effectively, the emission of chrome in the tanning waste water is reduced, and the product quality of the finished leather is enhanced at a certain degree.

The invention discloses a chromium-free tanning agent in the tanning industry and a synthetic production process thereof; the formula (weight ratio) comprises: 60-150 parts of amide containing hydroxymethyl, 30-100 parts of aliphatic aldehydes, and 1-5 parts of anti-yellowing agent. The production method comprises the following steps: in the first step, 60-150 parts of amide containing hydroxymethyl are added into a reaction kettle with a stirring function, a thermometer, a reflux condenser and a vacuum distillation unit; in the second step, temperature is raised to 30 to 40 DEG C; in the third step, 30-100 parts of aliphatic aldehydes are dripped; in the fourth step, 1-5 parts of anti-yellowing agent are added with 2-4 hours of heat insulation; and in the fifth step, decompression distillation is carried out for 4-6h at the temperature of 50-90 DEG C and the pressure of -0.3bar-0.95bar for removing the water. The third step and the fourth step can be exchanged. The invention solves the color changing problem in the production and storage processes of the products, adds a small amount of anti-yellowing material alkali metal and the borate solution of alkaline earth metal, greatly improves the storage conditions of the 'oxazolidine' type tanning agent, and prolongs the quality guaranteeing time; as the anti-yellowing material has low price, is easy for acquisition, and has small adding amount, the invention does not affect the application characteristics of the products and can be widely promoted.

The invention discloses a manufacturing technology for flame-retardant, light-resistant, low-fogging and degradable cowhide car seat cushion leather. According to the manufacturing technology, ammonium salt deliming is replaced by ammonium-salt-free deliming, tetrakis hydroxymethyl phosphonium sulphate and a flame-retardant starch-type leather surfactant are selected as a leather tanning agent to replace a traditional chrome tanning agent, the fogging value of the seat cushion leather is reduced through high-temperature washing, the flame-retardant property of the leather is improved through retanning, fat liquoring and coating step by step, the light resistance of a coating is improved through a light-resistant material, and the usage quantity of leather chemicals is decreased by selecting roll coating to replace spray coating.

The leather tanning agent having no chrome or having little chrome is made up by using amine material containing carboxymethyl group and aliphatic aldehyde compound through the processes of N-carboxymethylation reaction and ring-closing reaction. In addition to oxazolidine naphthenicbase its molecular structure also contains several functional groups of aldehyde group, carboxyl group, hydroxyl group and quaternary amino-group. Said main tanning agent can be combined with vegetable tannin extract, also can be combined with chrome for tanning leather, and can raise wet and thermal stabilizing of the finished leather and reduce dose of chrome by 30-40%.

The invention discloses a high pH value fast leather tanning method. The high pH value fast leather tanning method mainly comprises the following steps: pre-treating bare leather, penetrating by using chrome tanning agent, extracting alkali and the like. Organic acids and salts of organic acid are used in the pre-treating step of the bare leather to reduce pH value of the bare leather around the isoelectric point so as to form effective masking, or organic acids and salts of organic acid are used to reduce pH value of the bare leather to 6+ / -0.2 and 0.4-0.6wt% masking agent is added to the bare leather to form effective masking. In the chrome tanning step, positive chrome ions in the chrome tanning agent combine with peptide chain carboxyl ions R-COO- to form coordinate bonds to complete leather tanning. The high pH value fast leather tanning method provided in the invention has advantages such as short tanning time, is free of traditional acid etching process, and has small discharge of waste water with high chloride ion content, high use ratio of chrome tanning agent, high quality of finished leather and the like.

The invention discloses amphiprotic acrylic resin leather tanning agent with an effective constituent structure which is as shown in the specification. The preparation method comprises the following steps of: dissolving acrylic acid and methyl acrylic acid in deionized water, stirring, dropwise adding aqueous alkali to obtain a monomer aqueous solution A; dissolving (methyl) dimethylaminoethyl ester acrylate, acrylic amide and a chain transfer agent in deionized water to obtain a monomer aqueous solution B; preparing an initiator aqueous solution C by using ammonium sulfate; adding allyl polyether (APEG) and deionized water to a reactor, stirring and heating up, simultaneously dropwise adding the monomer aqueous solution A, the monomer aqueous solution B and the initiator aqueous solution C, further reacting after the three are simultaneously added, and cooling to obtain amphiprotic acrylic resin leather tanning agent. In addition to the filling and re-tanning functions, the amphiprotic acrylic resin leather tanning agent disclosed by the invention further can be used for pretanning before chrome tanning, so that the usage amount of the chrome tanning agent is reduced, a color shading phenomenon can be avoided, and the absorption of dye and fatting agent is improved.

A preparation method of an aluminum-oxidized starch complex tanning agent comprises steps of: first mixing starch and water, adding concentrated nitric acid and a catalyst, and stirring for reaction, washing reaction products with ethanol or acetone to obtain the oxidized starch; and evenly mixing the oxidized starch and aluminum ions, oscillating, steaming out excessive water by a rotary evaporimeter, and drying the obtained product. The method of the invention can effectively improve the tanning property of the aluminium tanning agent, maintain original advantages of the aluminum tanning agent and greatly mitigate the phenomenon of detanning. The method of the present invention employs nitrate as an oxidant to oxidize hydroxyl groups to generate oxidized starch with high degree of carboxylic substitution, and utilizes a principle of acid degradation to reduce the relative molecular mass of the oxidized starch, so as to obtain aluminum-containing macromolecular tanning agent with good permeability, high absorption rate and excellent tanning property. The obtained leather tanning agent has good tanning and filling performances, and is suitable for main tanning and retanning; after the main tanning, a pickled skin has a shrinkage temperature raised to 90 DEG C, gains pure white leather body and obvious thickness increase; and after retanning, a product has good elasticity, bright color, gloss, and soft and full handle.

The invention discloses a method for preparing dialdehyde carboxymethyl cellulose and a method for detecting aldehyde content, wherein the method for preparing dialdehyde carboxymethyl cellulose comprises the following steps: dispensing sodium carboxymethyl cellulose 100 parts by dry weight and oxidant 80-100 parts by dry weight into solution reaction system, adjusting pH value scale of the reacting system between 1.5 and 4.0 and the reaction temperature between 25 and 45 DEG C to react for 1-10 hrs, charging precipitant to make the product precipitate and enabling the produce is dissolved out completely, and obtaining the product dialdehyde carboxymethyl cellulose which aldehyde group content is detected by hydroxylamine method via separating, washing and drying. By adopting the invention for preparing dialdehyde carboxymethyl cellulose, the aldehyde content can be controlled. A plurality of side reactions are prevented due to using periodic acid and periodic acid salt which is provided with high-degree selectivity as oxidant, thereby improving the raw material utility. The prepared dialdehyde carboxymethyl cellulose of the invention can be a biological medical material and a green leather tanning agent.

The invention relates to a preparation method of a modified Chinese gall tanning extract environmentally-friendly leather tanning agent. Graft modification is performed on a Chinese gall tanning extract with p-hydroxy benzenyl sulfonate sodium and nekal under the catalytic action of horseradish peroxidase / H2O2 so as to obtain the environmentally-friendly leather tanning agent. The nekal is introduced into the leather tanning agent, so that the dissolubility of the Chinese gall tanning extract and the penetrability of the Chinese gall tanning extract in a leather fiber can be improved remarkably; and the p-hydroxy benzenyl sulfonate sodium is introduced, so that the tanning effect of the Chinese gall tanning extract can be enhanced. When the modified Chinese gall tanning extract related bythe invention is applied to major tanning, the shrinkage temperature can be raised to be 70 and 75 DEG C and leather thickening effect is remarkable; when the Chinese gall tanning extract is applied to retanning, the Chinese gall tanning extract has high seepage velocity, the leather body of finished leather is full, has moderate elasticity and fine grain surface, and incision fibers have high dispersibility and light colors; and the product is beneficial to the realization of environmentally-friendly leather production and plays a positive role in reducing pollution caused by leather tanning.

The invention discloses a method for recycling chromium sludge from waste liquor obtained through leather tanning, and belongs to a technology for recycling waste liquor obtained through leather tanning. The method comprises the following steps of: filtering the waste liquor discharged after tanning by using a grate and a screen, settling in a liquid storage tank, and concentrating to obtain chromium sludge cakes, and is characterized by also comprising the following step of: transferring the chromium sludge cakes into an acidification tank, adding 1 to 3 weight percent of 98 percent concentrated sulfuric acid, and fully stirring to obtain Cr2(SO4)3 recyclable chromium sludge with higher Cr+3 content. The pH value of the recyclable chromium sludge obtained after the concentrated sulfuric acid is added and fully stirred is controlled to be 5.5-6.5. Primary implementation prove that: a tanning agent prepared from the recyclable chromium sludge and newly added chromium powder in a ratio of 2:1 is used for a tanning procedure, so that the waste liquor discharged after tanning is reduced by 98 percent, resources are recycled and production cost is saved; and if 40 tons of waste liquor discharged after tanning is treated daily, 100kg of chromium can be recycled, and the production cost is saved by 0.72 million yuan each year based on 300 days a year.

The invention relates to a method for preparing an aldehyde-containing polyurethane-acrylate resin tanning agent. The aldehyde-containing polyurethane-acrylate resin tanning agent is prepared from a polymerizable nonionic polyurethane oligomer and unsaturated aldehyde by carrying out radical copolymerization in distilled water. The tanning agent contains aldehyde group, can be combined with a covalent bond of hide collagen fibers, has obvious tanning function, can make leather obtain higher hydrothermal stability when reducing the use amount of a chrome tanning agent, has excellent selective filling property, can make the leather have soft and plump hand feeling and exquisite grain, can be assorted with the chrome tanning agent to use in the low pH value environment of chrom tanning and chrome retanning, is favorable to adsorption fixation of the chrome tanning agent, can obviously reduce content of chromium salt in chrom tanning liquid waste so as to greatly reduce pollution of the tanning liquid waste to the environment, is a novel multifunctional environment-friendly leather tanning material and is suitable for tanning processing of sofa leather, instep leather, clothing leather and the like.

The invention relates to a preparation method and application of a graphene oxide-loaded titanium dioxide coupling material. The coupling material is prepared by the following steps: carrying out preoxidation and deep oxidation on graphite powder and then carrying out ultrasonic treatment to obtain single-layer graphene oxide, preparing titanium dioxide through a sol-gel method and coupling the titanium dioxide to the graphene oxide. The preparation technology of the material is simple and industrial production is easy to implement. The prepared coupling material has photocatalytic activity of the titanium dioxide and has adsorptive property of the graphene oxide, and hexavalent chromium in wastewater can be effectively removed. A product can be applied to treatment of electroplating wastewater, leather tanning wastewater and printing and dyeing wastewater.

The invention discloses an oxidized graphene and trivalent chromium composited tanning agent. The oxidized graphene and trivalent chromium composited tanning agent is prepared from the following raw materials in parts by weight: 50-60 parts of oxidized graphene nanosheet dispersion liquid, 6-8 parts of potassium dichromate, 10-15 parts of sodium carbonate, and 0.5-0.1 part of a dispersing agent. The invention further discloses a preparation method of the oxidized graphene and trivalent chromium composited tanning agent. The leather tanning agent disclosed by the invention has the advantages of low dosage for tanning, high absorptivity and low residual amount of a chromium compound in the waste liquor; furthermore, the production technology for the tanning agent is special, the technical process is easy to operate, and the tanning agent is of a good application prospect.

The invention belongs to the field of leather tanning technologies, and relates to a less-chrome tanning technology for tanning sheep skin through a nano-composite high absorption chrome tanning assistant. According to the traditional tanning technology, the absorption rate of chrome is not high, so serious waste of chrome resource and pollution are caused and the ecological environment is damaged. According to the tanning theory and the structure characteristics of collagenous fibers and nano-composite high absorption chrome tanning assistant, the nano-composite high absorption chrome tanning assistant and a little of chrome powder are matched and used for tanning goat acid skin, wet blue shrinkage temperature exceeds 100 DEG C, the thickening rate is higher by 50% than that of the leather tanned with conventional 8% of chrome powder, the content of Cr2O3 in the waste liquid is reduced to 50mg / L, and the absorption rate of chrome is improved to be 99%. The mechanical strength of the crust leather is equivalent to normally chrome tanned leather, and SEM (scanning electron microscope) representation results show that the nano-composite high absorption chrome tanning assistant is beneficial to scattering the collagenous fibers, but does not damage the triple helix structure of the collagenous fiber, so that the stability of the collagen structure is guaranteed.

The invention discloses an oxidized graphene and water-soluble vinyl monomer copolymerized leather tanning agent. The leather tanning agent is prepared from the following raw materials in parts by weight: 20-30 parts of oxidized graphene nanosheet dispersion liquid, 0.5-1 part of an oxidizing agent, 60-80 parts of a monomer mixed solution, and 20-30 parts of an initiator. The invention further discloses a preparation method of the oxidized graphene and water-soluble vinyl monomer copolymerized leather tanning agent. The preparation method adopts the water-solution free radical polymerization reaction to implement the free radical copolymerization reaction for double bonds in the oxidized graphene structure and the water-soluble vinyl monomer, so that the obtained copolymer both comprises the oxidized graphene nanosheet and the water-based vinyl structural unit; furthermore, the size of the oxidized graphene nanosheet can be reduced and the distribution can be more uniform, and the tanning agent can generate the chemical bond function and the nanometer size effect after the tanning agent permeates the leather collagenous fibers, so as to obtain the tanning effect on the leather fibers; the tanning agent can serve as the leather tanning agent separately.

The invention discloses amphiprotic leather tanning agent and a preparation method thereof. The preparation method of the amphiprotic leather tanning agent comprises the following steps of: based on weight parts, adding an SMA (Styrene Maleic Anhydride) copolymer, N, N-dimethyl fatty alcohol amine and a catalyst to a reaction kettle in which a condensing device is installed; adding a solvent to react, and measuring a hydroxyl value in the reaction system; adding dimethyl sulfate to react when the hydroxyl value (in terms of solid) is smaller than and equal to 10 (mg KOH / g); distilling under reduced pressure under the vacuum condition to remove the solvent; and adjusting a pH value by using an alkali aqueous solution; and adjusting the mass concentration of the product to 20%-40%. The amphiprotic leather tanning agent disclosed by the invention not only retains the filling performance of the SMA tanning agent, but also improves the color fading defect of the SMA tanning agent. Meanwhile, the modified SMA tanning agent has good emulsifying dispersion; and the leather body, which is tanned again by the amphiprotic tanning agent, is full and soft, and is good in elasticity and higher in tensile strength and tearing strength.

The invention relates to the field of leather processing reagents, and provides a leather tanning agent and a preparing method thereof. The problems that in the prior art, a leather tanning agent is not environment-friendly, the tanning effect is poor, and the preparing method is complex are solved. The leather tanning agent comprises following raw materials including, by weight, 10-15 parts of oxidized graphene, 90-110 parts of modified starch, 50-65 parts of (3-aminopropyl)-trimethoxysilane and 30-40 parts of 3,4-ethylenedioxythiophene.

The invention discloses a titanium tanning agent / graphene-oxide nanometer composite tanning agent. The titanium tanning agent / graphene-oxide nanometer composite tanning agent is prepared from, by mass, 40-50 parts of titanium salt solutions, 40-50 parts of graphene oxide nanometer-sheet layer dispersion liquid and 5-8 parts of dispersing agent. The invention further discloses a preparing method of the titanium tanning agent / graphene-oxide nanometer composite tanning agent. The tanning agent can be used as a leather tanning agent; when the weight of the solid titanium tanning agent / graphene-oxide nanometer composite tanning agent is 5% of that of leather, the shrinkage temperature of the tanned leather is up to 105 DEG C, the absorption rate of the titanium tanning agent is 95%, the absorption rate of graphene oxide is larger than 99%, the tanned leather is washable and resistant to storage, and has the good softness, elasticity and fullness.

The invention discloses a black leather tanning method which adopts the technical proposal of plant tannin initial tanning and chromium-iron lignosulfonate re-tanning. The dosage of Cr2O3 in chrome tanning agent is 1.5 weight percent to 1.8 weight percent, the dosage of Fe2O3 in the chrome tanning agent is 0.7 weight percent and the dosage of chestnut tannin is 5 weight percent, which are quite an appropriate combination for tanning black leather. The technical proposal obviously reduces the dosage of the chrome tanning agent and even does not use black dyes; the obtained leather is soft to touch and has tender grain surface. The method reduces the environment pollution during leather tanning, simplifies the process, shortens the production cycle and has good economic and social benefit.