KR830000756B1 - The use fine-particuiate water-insoluble alkaline aluminium silicates in the production of leather - Google Patents

Abstract

Finely divided alkali metal Al silicates were used in combination with surfactants for the degreasing and pretanning of pickled skins. Thus, pickled sheppskins for vegetable-tannel lining leather were degreased and pretanned by drumming 90 min at 38≰C with H2O 50, polyalkylene glycol alkylphenyl ehter 3, and Na aluminosilicate 5% (based on skin wt.) dilg. with 100% H2O at 38≰C and drumming 60 min, draining the liquor, and washing the skins 15 min with H2O at 35≰C. The treated skins were vegetable tanned, bleached, and dried in the usual way to give good quality lining leather.

Description

Tannery method using particulate water-insoluble alkali aluminum silicate

The present invention relates to a tanning method for treating leather using particulate water-insoluble alkali aluminum silicate.

In the manufacture of leather products, the most urgent problem is the problem of partially or completely replacing supplements that severely contaminate industrial wastewater. This is especially a problem during the degreasing and pretensioning of the soft, lightly treated leather, and when tanning hides and leather products. In this process, auxiliaries such as solvent degreasing agent, surfactant, electrolyte, phosphate, and neutralizing agent are added to the tanning agent.

According to the present invention, it is possible to reduce the amount of chemicals used and the degree of wastewater contamination during tanneries. For this purpose a special alkaline aluminum silicate according to the invention is used, which makes it possible to partially or completely replace commonly used auxiliaries and to significantly improve the condition of the waste water because it is physiologically harmless.

The use of alkaline aluminum silicates has proved to be particularly beneficial for the following methods.

A. Degreasing and pre-tanning of soft hides

Pre-treated soft hides, which are commonly used as samples of leather products, are pretreated with salts and acids and stored. The pH value of the raw material in this state is <2.

When carrying out the degreasing process prior to actual tanning, it is important to avoid damaging the leather structure by swelling. This is usually done with a concentrated salt solution (6 ° to 8 ° / B'e). According to the tanning method, anionic or nonionic surfactants, possibly solvents, are added to the degreasing solution. Since the tanning action of polyphosphates is known, polyphosphates such as hexametaphosphate are added when softening and degreasing leather raw materials. Swelling is prevented by the light tanning action of these polyphosphates. However, the tanning action itself is not clear enough to characterize the leather product in this tanning state.

In the degreasing and tanning of the soft acid-treated leather, alkaline aluminum silicate has the following advantages.

1. The risk of water pollution caused by wastewater containing phosphate can be prevented by using less phosphate.

2. The use of solvents to degrease softly dilute leather may be partially or completely exempted.

3. Alkaline aluminum silicate has very high acid binding ability, so it has the effect of removing dilute acid treatment.

4. As is known by the use of polyphosphates, the problem of formation of colored chromium-phosphate complexes in subsequent chrome tanning operations can be avoided.

Tanning of hides and leather products

The most important of the tanning methods is chrome tanning. This is based on the formation of azido complexes and the aggregation of basic chromium salts with the carboxyl groups of collagen.

In addition to these, other basic metal salts such as iron, aluminum, zirconium, titanium and silicon salts also exhibit a tanning action. In practice, however, only certain aluminum and zirconium salts have been found suitable as tannery compounds. In general, samples such as specialty glasses are difficult to handle in acid tanning media and therefore practically no silicone compound is used. In addition, the quality of leather products is usually unsuitable, especially after aging, because they are stiff and brittle and lose their durability to rupture.

The use of alkaline aluminum silicate salts gives the following advantages, especially in the case of chrome tanning or in combination with chromium, aluminum and silicon tanning agents.

1. Waste water pollution in tannery plants is significantly reduced due to the reduced use of chrome tanners. The chromium content is thus reduced more than directly proportional. If the amount of chromium in the liquid is reduced by 50%, Dr. Wasser, Luft and Betried, 3rd edition (1964) As described by Ing Siegfried Felten, the chromium content of the wastewater contains only up to 15% of the conventional amount as compared to pure chromium tanning.

2. The defect of the above-mentioned silicone tanning agent is eliminated. This is because alkaline aluminum silicate in an acidic medium (pH 3-4.5) present at the time of tanning dissolves to form finely distributed sodium salts, aluminum salts and polymerizable silicic acid.

3. In combination tanning, alkaline aluminum silicate has a self-neutralizing effect due to its own consumption of acid. Therefore, there is no need to use additional neutralizer. Tanning takes place simultaneously.

4. Alkali aluminum silicate to be used in the process of the present invention can be used as a neutralizer when neutralizing chromium leather products, without changing the leather products to unnecessary green color by polyphosphate.

5. Waste waters contain only a small amount of electrolytes as compared to conventional methods, since they can be partially or completely exempted from common salts and other electrolytes.

6. Alkali aluminum silicate is easy to store and there is no danger in handling.

In the method of this invention, the tannery method using the particulate water-insoluble alkali aluminum silicate of the following general formula containing water as much as possible is provided.

(Cat ₂ O) x Al ₂ O ₃ (SiO ₂ ) y

Wherein Cat is an alkali metal ion, preferably sodium ion, x is a number from 0.7 to 1.5, y is a number from 0.8 to 6, preferably 1.3 to 4.

The particle size of the alkali aluminum silicate is 0.1 to 25μ, preferably 1 to 12μ, calcium binding capacity is 20 to 200mg CaO per 1g of anhydrous active agent.

The process of the invention is carried out in a high acidic pH range.

Calcium binding capacity is determined by the manner given in the Examples.

Alkali silicates for use in the process of the present invention can be synthesized by simple methods, such as by reacting water-soluble silicates with water-soluble aluminates in the presence of water.

For that purpose, the aqueous solutions of the sample can be mixed with each other, or one component in the solid state may be reacted with another component in the aqueous state. The required alkali aluminum silicate can also be obtained by mixing two solid components in the presence of water. Alkali aluminum silicate may be prepared from Al (OH) ₃ Al ₂ O ₃ or SiO ₂ by reaction with an alkali silicate solution or aluminate solution. Finally, this kind of material can also be formed from the melt, but this method is not very economically feasible because it requires a high melting temperature and changes the melt into a finely distributed product. can not do it.

Alkali aluminum silicates, prepared by precipitation or otherwise finely distributed by other methods, change the state of aging or crystallization from an amorphous state by heating to a temperature of 50 to 200 ° C. You can. The amorphous or crystalline aluminum aluminum silicate present in the liquid suspension can be separated from the remaining aqueous solution by filtration and dried, for example, at a temperature of 50 to 800 ° C. This product contains some amount of bound water depending on the drying conditions.

Anhydrous products are obtained at 800 ° C. However, hydrated products are those obtained by drying at 50 ° to 400 ° C, in particular 50 to 200 ° C. Examples of suitable products are those having a moisture content (relative to total weight) of about 2 to 30%, usually about 8 to 27%.

Precipitation conditions aid in the formation of small particles of between 1 and 12 μm, so that intermixed aluminate and silicate solutions can also be introduced simultaneously into the reactor, which is subject to high shear forces, for example vigorously shaking. When producing precipitated aluminum silicate (preferably these are used in the process of the invention), the formation of large, possibly interpenetrating crystals is prevented by slow agitation of the crystallization compound.

However, it is advisable to remove these secondary particles, for example by means of an air separator, since unwanted agglomeration of the crystal grains may occur upon drying. Roughly alkaline aluminum silicates and alkali aluminum silicates ground to a desired grain size can also be used. For example, mills and / or air separators or mixtures thereof are suitable for this purpose.

Preferred products are, for example, synthesized from crystalline aluminum silicate of the following composition.

0.7-1.1Cat ₂ O. Al ₂ O _3. 1.3-3SiO ₂

Cat is an alkali cation, preferably a sodium cation. It is beneficial when alkaline aluminum silicate crystals have rounded edges or corners.

When preparing alkali aluminum silicate having rounded edges and edges, it is preferable to start with a formulation having a molar composition in the following range.

2.5-6.0 Cat ₂ O. Al ₂ O ₃ . 0.5-5.0 SiO ₂ . 60-200H ₂ O

In the above formula, Cat is the same as described above, and particularly represents sodium ions.

This formulation is crystallized by known methods. Advantageously this is done by heating the preparation to 70-120 ° C., preferably 80-95 ° C. for at least 1/2 hour under shaking. Crystals are separated in a simple manner by liquid phase separation. If necessary, the crystals may be washed again with water and dried before further processing. Even if the composition is carried out using a slightly different composition from the above, it is also possible to obtain products with rounded corners, especially if only one of the four concentration parameters is different.

Furthermore, according to the process of the present invention, particulate water-insoluble alkali aluminum silicate precipitated, aged or crystallized in the presence of a water-soluble inorganic or organic dispersant can also be used. This kind of product can be obtained in a technically simple manner. Suitable water-soluble organic dispersants are compounds having a compound-forming ability with surfactants, non-interfacial aromatic sulfonic acids and calcium. These dispersants may be introduced into the reaction mixture in any manner before or during precipitation, such as introduced in solution or dissolved in the aluminate solution and / or silicate solution. A particularly satisfactory effect occurs when the dispersant is dissolved in the silicate solution. The amount of dispersant should be at least 0.05% by weight, preferably 0.1-5% by weight relative to the total amount of the sample solution. The sample solution is heated to a temperature of 50 to 200 ° C. for 1/2 to 24 hours for the purpose of ripening or crystallization. Important among the many dispersants that can be used are sodium lauryl ether sulfate, sodium polyacrylate, diphosphonic acid hydroxyethane and the like.

The compound of the following general formula forms a special kind of alkali aluminum silicate used in the method of the present invention with respect to its crystal structure.

_{0.7-1.1Na 2 O · Al 2 O 3} > 2.4-3.3SiO 2

Their use as soaping aids is no different from that of the other types of alkali aluminum silicates described above.

Compounds of the following general formulas are another variant of particulate water-insoluble alkali aluminum citrate for use in the process of the invention.

0.7-1.1 Na ₂ O Al ₂ O ₃ 3.3-5.3 SiO ₂

When producing this kind of product, it is preferable to start using a formulation having the following molar composition.

2.5-4.5Na ₂ O: Al ₂ O ₃ : 3.5-6.5SiO ₂ : 50-110H ₂ O

This formulation is crystallized by known methods. This crystallization is carried out by heating the preparation to a temperature of 100 to 200 ° C, preferably 130 to 160 ° C for at least 1/2 hour under vigorous shaking. The crystallized product is isolated in a simple way by liquid phase separation. If necessary, the product is washed with water and dried at 20 to 200 ° C before further processing. The dry product still contains bound water. The manufacture of the product by the method described produces extremely fine crystal grains which aggregate to form a sphere, possibly a hollow sphere having a diameter of about 1 to 4 .mu.m.

燒)된(구조가 파괴된 것) 카올린으로부터 제조될 수 있다.Furthermore, alkaline aluminum silicate suitable for use in the method of the present invention is calcined by hydrothermal treatment using an aqueous alkali hydroxide solution (

Iii) can be prepared from kaolin which has a broken structure.

The following structural formula corresponds to the product.

0.7-1.1 Cat ₂ . Al ₂ O ₃ . 1.3-2.4SiO ₂ . 0.5-5.0H ₂ O

Wherein cat is an alkali cation, in particular a sodium cation.

The production of alkali aluminum silicates from calcined kaolin allows the production of extremely fine granular products directly without particular technical problems. The kaolin previously calcined at 500 to 800 ° C. is hydrothermally treated using an aqueous alkali hydroxide solution at 50 to 100 ° C. The resulting crystallization reaction is usually terminated after 0.5 to 3 hours.

Commercially available repair kaolin is mainly Al ₂ O ₃ · 2SiO ₂ . It is composed of clay mineral kaolinite of the same composition as 2H ₂ O and has a layered structure.

Here, in order to obtain an alkali aluminum silicate for use in the present invention as a hot water treatment using an alkali hydroxide, it is necessary to first destroy the kaolin, which can be most advantageously performed by heating the kaolin at a temperature of 500 to 800 ° C. for 2 to 4 hours. have. X-ray amorphous anhydrous metakaolin is thus prepared from kaolin. In addition to the structural destruction treatment of kaolin by calcination treatment, kaolin can also be destroyed by mechanical treatment (milling) or acid treatment.

The kaolin available as a sample is an off-white powder with high purity and its iron content, about 2000 to 10,000 ppmFe, is significantly higher than the value of 20 to 100 ppmFe in alkaline aluminum silicate prepared by precipitation from alkali silicate and alkali aluminic acid solutions. will be.

Since iron is firmly embedded in the form of iron oxide in the alkali aluminum silicate lattice and does not elute, it is disadvantageous if the iron content in the alkali aluminum silicate prepared from kaolin is high. Sodium aluminum silicate having a cubic faujasite-like structure is produced during hydrothermal treatment of sodium hydroxide on kaolin that has destroyed the structure.

Alkali aluminum silicates useful by the present invention can also be prepared from calcined (grinded) kaolin by hydrothermal treatment using an aqueous alkali hydroxide solution with addition of silicon dioxide or a compound that produces silicon dioxide. The mixture of alkali aluminum silicates of different crystal structures thus obtained is composed of particulate crystal particles having a diameter of less than 20 µm, and 100% of the mixture is composed of particles having a diameter of less than 10 µm. In fact, the change reaction of this crushed kaolin is preferably carried out with soda solution and water glass. Sodium aluminum silicates known by various names in the literature, such as Molecula sieve 13 × or zeolite NaX (see “Molecular sieve” by 0. Grubner, P. Jiru and M. Palek, Berlin, 1968, pages 32, 85-89). Silver is preferably produced during hydrothermal treatment when the formulation is not shaken and only when low delivery forces are used but also when the temperature is maintained at a boiling point of about 10 to 20 ° C. or less. Sodium aluminum silicate J has a cubic crystal structure similar to that of natural paujasite.

The change reaction is influenced by the shaking of the formulation, the elevated temperature (boiling at atmospheric pressure or under high pressure) and the amount of silicate, ie, the molar ratio of SiO ₂ : Na ₂ O of at least 1, preferably from 0.1 to 1.45 or higher and in addition to or from sodium aluminum silicate J. Instead, aluminum silicate Namul F is produced. Sodium aluminum silicate F is specified in the literature as "zeolide P" or "form B" (see DW Breck, "Zeolite Molecular Sieve, New York, 1974, page 72). And garniite-like structures, present in the form of spherical crystals.Generally, the conditions for the preparation of sodium aluminum silicate and for the mixture of J and F are less critical than those for pure crystalline A. to be.

Gentlely dilute leather is degreased and preliminarily known in known methods, such as in a batch of both. Alkali aluminum silicate is preferably used in combination with a surfactant, in particular an anionic light nonionic surfactant.

Particularly suitable anionic surfactants are those having 8 to 18 carbon sulfates or sulfonates, such as primary or secondary alkyl sulfates, alkylsulfonates or alkylarylsulfonates. Suitable nonionic surfactants are, for example, from 5 to 30 moles of ethylene oxide, higher fatty alcohols, alkylphenols, fatty acids or fatty acids amines having 8 to 18 carbon atoms. Depending on the product to be cleaned, it is advisable to select and use mixtures or individual types of anionic or nonionic surfactants.

In addition, it is possible to add alkali aluminum silicate to a known liquid as a separate adjuvant, or to use these together with a small amount of chromium tanning agents.

For the process by the process of the invention, 10 to 50 g / l surfactant and 10 to 50 g / l alkali aluminum silicate are required.

Furthermore, the addition of grease solvents in amounts of 50 to 100 g / l may aid the grease dissolution of the liquor when degreasing the softly dilute leather with high fat content. Suitable solvents are selected from petroleum hydrocarbons, aromatic hydroxides, alkylbenzenes and mineral oils. In general, however, no solvent may be used.

The tanning of hides and leather products is also carried out by known methods, and known tanning agents such as vegetable synthetic tanning agents, chromium tanning agents, etc., together with the addition of common salts and electrolytes such as inorganic or organic acids such as sulfuric acid, formic or acetic acid It is used depending on the type of product. Dilute acid treatment and tanning can be used together by a well-known method. The leather product may be repeatedly tanned and degreased.

In the above-mentioned tanning treatment, the amount of the alkali aluminum silicate used is 5 to 80 grams per liter of the tanning treatment liquid. Alkali aluminum silicates can also be advantageously used in the neutralization of leather products as they are decomposed in the acid medium by the formation and alkali bonding of alkali salts, aluminum salts, and polymerizable silicic acids. In this case, 2 to 20 g / L of alkali aluminum silicate is required.

The advantages of the present invention first mentioned herein over the known methods can be achieved by using particulate water-insoluble alkali aluminum silicates. Alkali aluminum silicates are dry powders, which can be easily converted into a stable dispersion by controlled zoom in a solution containing water or a dispersant, which can be used satisfactorily in this form, and of course can be easily diluted with water.

The method of the present invention is described as an example as follows.

EXAMPLE

Preparation of Suitable Alkali Aluminum Silicates

The silicate solution was added to the alumina solution which was vigorously shaken in a 15 liter reactor. It was shaken at 3000 r.p.m. using a shaker with a dispersion disc. These two solutions were brought to room temperature.

Under exothermic reaction, x-ray amorphous sodium aluminum silicate was produced as the primary precipitation product. After shaking for 10 minutes, the precipitate suspension was transferred to a crystallizer and left to crystallize at 90 ° C. for 6 hours while shaking (250 r.p.m.). The solution was removed from the crystal sludge, washed with deionized water until the pH of the effluent reached about 10, and the filtered residue was dried. In lieu of dry aluminum sodium silicate, a suspension of crystallization product or crystal sludge may be used to make the sooping aid. The pre-dried product was heated to 800 ° C. for 1 hour to measure the moisture content. Sodium aluminum silicate was washed or neutralized with a solution having a pH of about 10, dried and then ground with a bowl mill. Particle size distribution was measured by needle balance. Calcium bonds of aluminum silicate were measured as follows.

1 g of aluminum silicate (called AS) was added to 1 L of an aqueous solution containing 0.594 g of CaCl ₂ (= 300 mg CaP / 1 = 30 ° dH), and adjusted to pH 10 with dilute NaOH. The suspension was then vigorously mixed for 15 minutes at a temperature of 22 ° C.-2 ° C.). After filtering the aluminum silicate, the residual hardness x of the filtrate was measured. From this formula,

(30-x) × 10

According to the calcium binding capacity was measured. The unit track is mgCaO / g AS. When calcium binding capacity is measured at high temperature such as 60 ° C, the value is much better than the value measured at 22 ° C.

Manufacturing conditions of aluminum sodium silicate A

Sedimentation: Composition

2.985 kg of aluminate solution of 17.7% Na ₂ O, 15.8% Al ₂ O ₃ , 66.6% H ₂ O.

Caustic soda 0.15kg. 9.420kg of water.

2.445 kg of a 25.8% sodium silicate solution of composition 1Na ₂ O, 6.0SiO ₂ , newly prepared from commercial water glass and alkali soluble silicic acid.

Crystallization: 6 hours at 90 ° C.

Drying: 24 hours at 100 ° C.

Composition: 0.9Na ₂ O. 1Al ₂ O ₃ . _{2.04SiO 2, 4.3H 2 O (=} 21.6% H 2 O).

Crystallinity: Fully Crystallized.

Calcium binding capacity: 170 mgCAO / g Active substance.

The particle size distribution measured by the sedimentation method was a maximum particle size of 3 to 6 mu. Sodium aluminum silicate A shows the following interference line in the X-ray diffractogram.

D-value obtained by Cα-Kα irradiation

It is clear that all these interference lines do not appear in the X-ray diffractogram, especially when the aluminum silicate is not fully crystallized.

Therefore, a very important value for indicating this kind is indicated by the sign of "(+)".

Manufacturing conditions of sodium aluminum silicate B

Sedimentation: Composition

13.2% Na ₂ O; 8.0% Al ₂ O ₃ ; 7.63 kg of aluminic acid solution of 78.8% H ₂ O.

Furtherance

8.0% Na ₂ O; 26.9% SiO ₂ ; 2.37 kg of sodium silicate solution of 65.1% H ₂ O.

Molar ratio: 3.24Na ₂ O; 1.0Al ₂ O ₃ ; 1.78 SiO ₂ ; 70.3H ₂ O.

Crystallization: 6 hours at 90 ° C.

Drying: 24 hours at 100 ° C.

Composition of dried product: 0.99 Na ₂ O. 1.00Al ₂ O ₃ . 1.83 SiO ₂ 4.0H ₂ O (= 20.9% H ₂ O)

Crystalline: Cube with large rounded corners and periphery.

Average particle size: 5.4μ

Calcium binding capacity: 172mgCaO / g active substance.

Conditions for the production of aluminum sodium silicate C.

Sedimentation: composition 14.5% Na ₂ O; 5.4% Al ₂ O ₃ ; 12.15 kg of aluminate solution of 80.1% H ₂ O

Composition 8.0% Na ₂ O; 26.9% SiO ₂ ; 2.87 kg of sodium silicate solution of 65.1% H ₂ O.

Molar ratio: 5.0Na ₂ O, 1.0Al ₂ O ₃ , 2.0SiO ₂ : 100H ₂ O.

Crystallization: 1 hour at 90 ° C.

Dry: Spray fine suspension of cleaning product (pH10) at 259 ° C. 46% solids content in this suspension

Composition of dry product: 0.96Na ₂ O, 1Al ₂ O ₃ , 1.96SiO ₂ , 4H ₂ O

Crystalline: Cube with very rounded corners and edges. Moisture content 20.5%

Average particle size: 5.4μ

Calcium binding capacity: 172mgCaO / g active substance.

Conditions for the production of aluminum calcium silicate D.

First, aluminum sodium silicate C was prepared. After removing the mother liquor, the crystals were washed with demineralized water to pH 10 and the filter residue was suspended in 6.1 L of 25% KCl solution. The suspension was briefly heated to 80-90 ° C. and then cooled, refiltered and washed.

Drying: 24 hours at 100 ° C.

The composition of the dry _{product: 0.35Na 2 O. 0.66K 2 O. 1.0Al} 2 O 3. 1.96 SiO ₂ 4.3H ₂ O (water content 20.3%).

Conditions for the production of aluminum sodium silicate E.

Precipitation: Composition. 36.0% Na ₂ O. 59.0% Al ₂ O _3. 0.76 kg of aluminate solution of 5.0% H ₂ O. 9.49 kg of water.

Furtherance. 8.0% Na ₂ O. 26.9% SiO ₂ . 3.94 kg of commercial sodium silicate solution of 65.1% H ₂ O.

Crystallization: 12 h at 90 ° C.

Drying: 24 hours at 100 ° C.

Composition: 0.9Na ₂ O. 1Al ₂ O ₃ . 3.1SiO ₂ · 5H ₂ O

Crystallinity: Fully Crystallized.

Average particle size: 3 to 6μ

Calcium binding capacity: 110mgCaO / g active substance.

Aluminum silicate E shows the following interference line in the X-ray diffractogram.

D value taken by Cu-Kα irradiation

Manufacturing Conditions of Sodium Aluminum Silicate F

Precipitation: Composition. 10.0 kg of aluminate solution of 0.84 kg NaAlO ₂ + 0.17 kg NaDH + 1.83 kg H ₂ O.

Furtherance. 8.0% Na ₂ O. 26.9% SiO ₂ . 7.16 kg of sodium silicate solution of 65.1% H ₂ O.

Crystallization: 4 hours at 150 ° C.

Drying: Hot spraying of 30% suspension of cleaning product (pH10).

Composition of dried product: 0.98 Na ₂ O. 1Al ₂ O ₃ . 4.12 SiO ₂ . 4.9H ₂ O

The particles are spherical and the average diameter of the spheres is 3-6 μ.

Calcium binding capacity: 132mg CaO / g active substance at 50 ℃.

Conditions for Preparation of Aluminum Sodium Silicate G.

Precipitation: Aluminate (14.8% Na ₂ O. 9.2% Al ₂ O ₃ .76.0% H ₂ O);

Silicate: (8.0% Na ₂ O. 26.9% SiO _2. 65.1% H ₂ O) 2.69 kg.

Molar ratio: 3.17 Na ₂ O. 1.0Al ₂ O _3. 1.82SiO _2. 62.5H ₂ O.

Crystallization: 6 hours at 90 ° C.

Composition of dried product: 1.11 Na ₂ O. 1Al ₂ O ₃ . 1.89 SiO ₂ . 3.1H ₂ O (= 16.4% H ₂ O).

Crystal structure: A mixture of 1: 1.

Crystal form: round crystals.

Average particle size: 5.6μ

Calcium binding capacity: 105 mgCaO / g active substance at 50 ° C.

Preparation conditions of sodium aluminum silicate H prepared from kaolin.

1. Structure breakdown of kaolin

In order to activate natural kaolin, 1 kg of the sample was heated to 700 ° C. in a vat and crucible for 3 hours. Thereby crystalline kaolin Al ₂ O ₃ . 2SiO ₂ . 2H ₂ O to amorphous metakaolin Al ₂ O ₃ . Switched to 2SiO ₂ .

2. Hydrothermal treatment of metakaolin.

The alkaline solution was added to the shake vessel and the calcined kaolin was added by shaking at a temperature of 20 to 100 °. This suspension was warmed to a crystallization temperature of 70 to 100 ° under shaking and held at this temperature until crystallization was complete. The mother liquor was actually removed and the residue washed with water until the pH of the wash liquor reached 9-11. The filtered solid was dried and then ground to a fine powder or ground to remove the coagulum formed during drying. This grinding step is omitted when further processing the filtration residue in a wet state or performing a drying operation with a spray dryer or a fluid dryer. Optionally, the hydrothermal treatment of calcined kaolin can be carried out in a continuous process.

Sedimentation: 1.65 kg of calcined kaolin. 10% NaOH 13.35 kg Mix at room temperature.

Crystallization: 2 hours at 100 ° C.

Drying: 2 hours at 160 ° C. in a vacuum drying chamber.

Composition: 0.88Na ₂ O, 1Al ₂ O ₃ , 2.14SiO ₂ , 3.5H ₂ O (= 18.1% H ₂ O).

Crystal structure: mixed crystal structure like sodium aluminum silicate G, but the ratio is 8: 2

Average particle size: 7.0μ

Calcium binding capacity: 126mgCaO / g active substance.

Preparation conditions of sodium aluminum silicate J prepared from kaolin.

Kaolin structure crushing and hydrothermal treatment were carried out in the same manner as in the case of sodium aluminum silicate H.

Precipitation: Calcined kaolin 2.6 kg 50% NaOH 7.5 kg Water glass 7.5 kg. 51.5 kg of deionized water. Mix at room temperature.

Crystallization: 24 hours at 100 ° C. without shaking.

Drying: 2 hours at 160 ° C. in a vacuum drying chamber.

Composition: 0.93Na ₂ O 1Al ₂ O ₃ 3.60SiO ₂ 6.8H ₂ O (= 24.6% H ₂ O).

Crystal structure: Cubic stirrup according to the above definition (aluminum sodium silicate J).

Average particle size: 8.0μ

Calcium binding capacity: 105mgCaO / g active substance.

Example 1

Degreasing and pre-tanning of softly dilute sheepskin for use in leather products for tanning diseases by biological activity:

Softly dilute the sheepskin (pH1.8 in leather) at 50% water at 38 ° C,

Alkylphenol polyglycol ether (9.5 EO) 3%,

It was immersed for 90 minutes in a 5% Na-Al silicate barrel obtained in Examples A, B and E, then diluted with 100% water at 38 ° C. and immersed again for 60 minutes (pH 3.8 to 4.0 of leather). The mother liquor was removed and the leather washed with water at 35 ° C for 15 minutes.

Skinning: Degreasing and pre-skinning tanning leather 100% water at 25 ℃,

Immersion treatment with commercially available 10% transparent and soft tanners, followed by immersion for 45 minutes in the same solution containing 4% auxiliary agent of commercial lubricants resistant to tannery, 10% mimosa tannery (powder), 10% Que The bracho tanning agent (powder) is added and tanned for 4 hours.

The leather product is then treated with a newly prepared solution for 30 minutes using 100% water and 0.5% oxalic acid to obtain shine. At this time, the pH value of the treatment tank is about 4.1 to 4.2.

The leather was rinsed at 25 ° C. for 15 minutes, and then rolled and dried by a known method.

Good quality endothelial leather products can be obtained during the degreasing and pretanning without the consumption of large amounts of ecologically harmful salts or polyphosphates.

Example 2

Taking of chrome tanned nappa Degreasing and pretanning of softly dilute sheepskin for leather products

In the same manner as in Example 1, the softly dilute treated hides are degreased and tanned (pH 3.8 to 4.0 in leather). The hides are subsequently washed at 35 ° C until the washings become clear.

Skinning: 100% water at 25 ° C, 5% of commercial soft tanners resistant to chrome tanners

30 minutes in tannery, 20% of commercially available soft chrome tanner,

Tanning time: 5 hours (pH 3.8 pH).

Hold for 1-2 days, then fold.

Subsequent tanning: 200% water at 45 ° C.,

Wash for 10 minutes, fresh liquid,

45 ℃ water 100%,

Commercial soft chrome tanner 3% -15 minutes,

2% -45 minutes lubricant resistant to chrome tanning and light resistant.

Soft neutral auxiliary tanning agent 4% -30 minutes,

PH 4.4 of the treatment bath, followed by washing at 50 ° C. for 10 minutes,

Lubricating: 150% water at 50 ℃

Commercially available soft leather lubricants 5-7% of natural or synthetic agents, 45 minutes,

The leather product thus treated is further processed and draped according to the known method. Good quality nappa leather is obtained by this method without using general salt or polyphosphate for deoxidation and degreasing.

Example 3

Skinning of sheepskin: Wash thoroughly and, if necessary, rinse the bleached sheepskin in a leather winch at 35 ° C for 15 minutes.

Dilute acid treatment and tanning: water, 30-35 ℃, liquid ratio 1: 20.

Common salt 60 g / ℓ,

5 g / l commercially available electrolyte-free skin lubricant, 35 minutes,

5 g / l of low molecular weight organic acid, such as a mixture of acetic acid and formic acid, left for 3 hours in a treatment tank overnight,

Commercially available powdered chrome tanner 4-5 g / l.

7 g / L of Al _a- Al silicate by Examples A, B, and C, and then left overnight (pH liquid 4.0 of liquid).

Then rinse for 15 minutes, spread out and let dry.

This method saves one-third to one-half the amount of chromium tanning agent, so that ecologically harmful components in the wastewater are reduced to about 0.5 g / l 4 without compromising the quality of the raw sheepskin.

Example 4

Chromium tanning of the right upper epithelium.

The soft calcareous swollen calcined by known methods is rinsed briefly at 20 ° and then reprocessed.

Regeneration and tanning path: 100% water, 20 ℃

7% of common salt,

10 minutes, 0.6% formic acid subsequent addition, 20 minutes,

0.6% sulfuric acid, 2 hours,

Left overnight in the treatment tank (pH 3.5 of the softened leather),

8% commercially available powdered chrome tanners,

Na-Al silicate 3% by Examples A, C, D for 5 hours (pH 3.8 in the treatment bath).

The tanned leather is left overnight, folded, neutralized, subsequently tanned and lubricated. The leather is then dried and finished in accordance with known methods.

In this way, the amount of chromium tanning agent can be saved from 10% to less than 8% without affecting the quality of the leather product.In this case, the chromium content in the waste water is about 8g / ℓCl ₂ O ₃ to 1g / ℓ. Can be reduced to less than.

Example 5

Neutralization treatment of right upper epithelium: prepared in the same manner as in Example 4.

Neutralization: Bended leather (pH3.7-4.2),

Rinse for 10 minutes at 35 ° C. 100% of water at 35 ℃,

Na-Al silicates 0.5 to 1% by Examples B, G and F, subcutaneous pH 4.5 to 4.7

Further processing is carried out as in Example 4.

By this method, a neutralizing effect can be obtained together with the subsequent tanning effect, and a pore stabilizing effect is observed.

Example 6

Skinning of White Cowhide:

Pretreatment of the soft hides, including descaling and swelling treatments, was carried out by known methods.

Combination of reprocessing and tanning treatment:

20 ° C. 100% water, 7% general salt, 10 minutes, 0.7% formic acid, 15 minutes, 0.7% sulfuric acid, 2 hours.

Softly leave the leather overnight in the dilute treatment bath (3.2 of the leather) Na-Al silicate 8%, 1.5% sulfuric acid by Example A, C, D and F in the same treatment tank, 5 hours (pH about 4.2) Unfold and then bend.

Subsequent tanning and lubrication: The washed leather was rinsed at 40 ° C. for 10 min and treated with the following fresh liquor.

40 ℃ water 100%

Neutral, soft, synthetic synthetic tannery 6%, commercial fat about 10 minutes, resistant to electrolytes and tanners, suitable for white leather; 10% for 45 minutes.

Commercially Available White Tanner 4%

30 minutes in the same solution.

New liquid. 45 ° C. water 200, 0.3% oxalic acid 0.3%, 15 min. Spread leather to dry.

Compared with the known tanning method using aluminum tanning agent and white tanning agent, the combination of the white tannery and Na-Al silicate of this embodiment can improve the water resistance and obtain a leather product of better quality than the commercially available quality.

Claims (1)

Raw leather or sebum is represented by the following general formula, characterized in that the particle size is 0.1 to 25μ, the calcium binding capacity is contacted with particulate water-insoluble alkali aluminum silicate, which optionally contains water, at 20 to 200 mg CaO per gram of anhydrous substance. The amount of the alkali aluminum silicate is used in combination in an amount of 10 to 50 g based on 1 L of the treatment liquid and 10 to 50 g of an anionic and / or nonionic surfactant for the degreasing and pre-tanning of the smoothly treated raw hides. In the case of tanning and / or post-treatment of raw hides and leather products, the silicate is used in combination with chromium tanning and / or biological tanning agents in an amount of 5 to 80 g / l, and for the neutralization of the leather after tanning, A tanning method, characterized in that it uses an amount of 2 to 20 g / l of silicate. (Cat ₂ O) _x Al ₂ O ₃ (SiO ₂ ) _y , wherein Cat is an alkali metal ion, x is a number from 0.7 to 1.5, and y is a number from 0.8 to 6.