JPS638500A - Chromium-aluminum tanning agent - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an improved chromium-aluminum tanning agent.

<Prior art> As is currently well known, various tanning agents have been proposed.
However, chrome tanning agents and tannin tanning agents are mainly used. Chrome tanning agents have been used since ancient times due to their outstanding tanning effects, and various basic chromium sulfates based on differences in basicity and chromium content are known, and have been used for the development of the leather industry. He has contributed greatly.

However, even with such effective romo tanning agents, some drawbacks have been pointed out in line with the demands of the times. The biggest problem is the environmental pollution problem caused by chromium compounds, and measures to treat chromium in tanning wastewater and leather sludge are required, and various studies are being conducted and practical applications are being promoted.

Countermeasures against this problem include (1) a so-called recycling method in which chromium-containing wastewater is returned to the chrome tanning process, (2) a so-called high-adsorption tanning agent method in which a tanning agent that improves chromium adsorption is used (3) A so-called chromium-saving tanning method has been proposed and partially implemented, in which the minimum necessary amount of chromium is used and other tanning agents are used.

The present invention is based on the method according to (3) above, in which the weight ratio is 0.7≦Cr2o3/A I. A method for producing a chromium-aluminum tanning agent characterized by neutralizing an acidic mixed aqueous solution consisting of a chromium sulfate-containing substance, an aluminum salt, and a carboxylic acid compound within the range of 03≦3 with an alkaline agent to make it highly basic. Developed (Special Public Interest Publication No. 60-40478)
Publication No.).

<Problems to be solved by the invention> The invention disclosed in Japanese Patent Publication No. 60-40478 uses chromium to improve the heat resistance of leather tanned using an aluminum tanning agent alone, and also significantly reduces the amount of chromium in waste water using the conventional chrome tanning method. It was found that the following points need to be improved, although this does not affect the reduction of chromium pollution load.

When tanning virgin hides, acids are released into the liquor as chromium and aluminum are adsorbed onto the hides, tending to push the pH of the liquor out of the preferred range required for a proper tanning operation, and therefore during the tanning process. It is necessary to keep the 1) H of the solution around a certain appropriate value by using some kind of acid binder, but adjusting the pH of the tanning solution is extremely important when performing tanning operations. If the value is too low, the bonding of chromium and aluminum to the leather will be insufficient, resulting in poor tanning and -h
If the pH value is too high, there is a danger that chromium hydroxide and aluminum hydroxide precipitates will form and good quality leather will not be able to brown.

Therefore, in the past, an alkaline agent such as soda carbonate or bicarbonate was added to the tanning solution in several stages during the tanning process in order to adjust the p If the process is not carefully and thoroughly controlled, such as the addition amount, addition method, and addition speed of the alkaline agent, which is measured at each stage during the process, trouble may occur that will impair the appearance and quality of the tanned leather that is finally obtained. There were some easy drawbacks.

The present invention was developed as a result of research to improve the drawbacks of the invention disclosed in Japanese Patent Publication No. 60-40478 as described above.

Means for Solving the Problems〉 That is, the present invention provides (a) Cr2032 to 25% by weight, A
1°032-25% by weight, caribonic acid compound 1-15
111fcr2 o3/A
100 parts by weight of a chromium-aluminum tanning agent having an I203 of 0.7 to 3 and a basicity of 20 to 55% and an acid binder of 0.2 to 50 parts by weight. It is a chromium-aluminum tanning agent characterized by:

Effects> The chromium-aluminum tanning agent of the above (a) in the present invention is made by neutralizing an acidic mixed aqueous solution consisting of an acid wachrom-containing aluminum salt and a carboxylic acid anhydride with an alkaline agent to make it highly basic. It is granulated by spray drying.

Here, the chromium sulfate-containing substance refers to chromium sulfate, base a VAFi chromium, or their mirabilite-containing substances, but industrially, sodium dichromate aqueous solution is used in the presence or absence of carboxylic acid. Alternatively, basic chromium sulfate produced by a reduction reaction with an R-free reducing agent is suitable.

Next, the aluminum salt is mainly aluminum sulfate, but other basic aluminum sulfate, aluminum chloride, basic aluminum chloride, etc. may also be used as necessary.

As is well known, carboxylic acid compounds are used as masking agents for OH groups when forming a high base. , tartaric acid, citric acid, lactic acid, etc., and they may also be alkali metal salts, alkaline earth gold rifA salts, or ammonium salts, and at least one or two or more of them may be appropriately selected and used.

Further, the alkaline agent is not particularly limited as long as it neutralizes each of the above-mentioned chemicals to make them highly basic, but for example, caustic alkali, alkali carbonate, alkali bicarbonate, or sodium aluminate can be used. Among these, sodium bicarbonate is particularly preferred because an alkaline agent that is as mild as possible is preferable for operational reasons.

The above-mentioned chromium sulfate-containing material, aluminum salt, and carboxylic acid compound are made into a mixed aqueous solution, and then mixed and stirred with an alkaline agent at a temperature of room temperature to 80° C. to gradually neutralize and make the solution highly basic.

Next, after the addition of the alkali agent is completed, the mixture is continued to be aged for a while, and if necessary, after being filtered, it is spray-dried by a conventional method to form a product into granules. The particle size of the product is preferably about 40 mesh, which can be dissolved in cold water, but is not limited thereto.

The composition of the chromium-aluminum tanning agent prepared by the above method is preferably in the following proportions (weight Φ%).

0r203 2-25fflff1% (preferably 8-20% by weight) A I□03 2-2511% (preferably 5-16% by weight Rubonic acid compound 1-15% by weight (preferably 6-15% by weight) Cr203 /^1203 (weight ratio) 0.7~3(
Preferably 0.8-2) Basicity 20-55% (preferably 2
8 to 50%) CrO/Al2O3 (When the II ratio is less than 0.7, the amount of aluminum in the liquid increases, and even if it relies on the masking effect of the carboxylic acid compound during basification, water will not be released during operation. It is said that the formation of aluminum oxide is likely to occur, making it impossible to obtain a high basicity, and at the same time, the manufacturing process requires an extremely long time, and the tanning performance of the resulting product is said to be more than compensated for by the drawbacks of chromium. This is because the tendency is unavoidable, and on the other hand, if it exceeds 3, the advantages based on the addition of aluminum will not be obtained much, and the practical effect will no longer be different from conventional chrome tanning agents.

In addition, the content of the carboxylic acid compound used as a masking agent depends on the desired set basicity, but it also depends on its type and the quantitative relationship between aluminum and chromium, and should be less than 1%. Then, the effect of the masking agent is 2.
On the other hand, if it exceeds 15%, not only will no significant masking effect be observed, but it will also be disadvantageous in terms of cost.

In addition, the content of Cr2O3 and A1゜03 is CrO
/Al□03 (weight ratio).

In addition, as the acid binder (b) of the present invention, calcined magnesium oxide is suitable, and natural magnesium oxide ore,
Calcined products of magnesium hydroxide and magnesium carbonate separated and collected from seawater and dolomite, fired products of magnesite,
Examples include those whose main component is calcined magnesium oxide, such as magnesia clinker.

Incidentally, calcined magnesium oxide can also be used together with, for example, dolomite, alkali metal carbonate, alkali bicarbonate, sodium sulfite, and the like.

These acid binders are usually used in powder form, but their reaction with free acids in tanning liquors is particularly influenced by particle size, and 100 mesh products are often preferred. The reason for this is 100
This is because particles larger than mesh may remain as insoluble matter during the tanning operation, and this may deposit on the surface of the tanned skin, resulting in point i.

The mixing ratio of the chromium-aluminum tanning agent in (a) and the acid binder in (b) depends on the basicity of the chromium-aluminum tanning agent, the type of acid binder, and the chromium-aluminum tanning agent after mixing the acid binder. Although it depends on the set basicity of the agent, in most cases, 0.2 to 0.2 to
50 parts by weight is preferred.

The reason is that if the amount is less than 0.21 parts, the alkaline content will be insufficient and an appropriate I)H value of the tanning solution will not be obtained;
This is because if the pH value of the tanning solution exceeds the φ range, gels of chromium hydroxide and aluminum hydroxide will form during the tanning process, making it impossible to perform the tanning process.

The tanning method using the chromium-aluminum tanning agent according to the present invention is basically no different from the usual chrome tanning method, and the tanning operation is not complicated at all.

The present invention will be specifically explained below with reference to Examples.

<Example> Example 1 Water was added to a glass-lined reactor equipped with a thermometer and a stirrer. 161.
! 1g Basic chromium sulfate (manufactured by Nihon Kagaku Kogyo Co., Ltd.) Neochrome > ioo, ○ Condensed sulfuric acid 7 /L
, Miniram (A12 (SO2>357%>
49. Seven tons of sodium formate (HCOONa 95%) 17.9 Ky was taken, heated to 60°C, and mixed with t9 for 60 minutes.

To this mixture, Mr# and sodium acid 13.9 to 9 were gradually added over 90 minutes. At this time, the base could be made highly basic without the formation of gel. After addition, the mixture was filtered according to a conventional method and then spray-dried to obtain dry granules of $145.0 kg. The composition of this dried granular material is Cr2o3 17.5% by weight A1°O35,
8% by weight HCOONa 11.7% by weight Cr2O3
/ to 1203 (weighted 3.0 basicity
The water solubility was 33.3%, indicating very good water solubility.

This granular dried product 145. Add 8.1 g of calcined magnesium oxide (~lqo 95.0%) to the fly and mix until homogeneous.Chromium-aluminum tanning agent 153
．． 7Kg is 1ζ.

The composition of this chromium-aluminum tanning agent was as follows.

Cr2O3 16.5% by weight Al2O35.5% by weight HCOONa 11.0% by weight Mg0
5.4% basicity by weight
60.7% Example 2 Water in the same reactor as Example 1 465.
3Ky basic 1iAWI chromium (Neochrome manufactured by Nihon Kagaku Kogyo) 100. (1gVA
Aluminum acid (A12 (S04) 357%>
213.8Kg Sodium acetate (CH
3COON a98, 5%) was taken, heated to 60°C, and stirred and mixed for 6C minutes. To this mixed solution, 59.9 Ng of bicarbonate was gradually added over 120 minutes. At this time, the base could be made highly basic without the formation of gel.

After the addition, the mixture was filtered according to a conventional method and then spray-dried to obtain 317.2 kg of dried granules. The composition of this dried granular material is Cr2O3 8.0% by weight A+203 11.4% by weight CH3COON
a 13.5 wt% Cr2O3/AAl203
(1 ratio) 0.7 Basicity 33.3
%, and the water solubility was very good.

Calcined magnesium oxide (MchO95.0%) was added to 317.2 KFI of this granular dry product at 19. Add OKy and mix until uniform.Chromium-aluminum tanning agent 33
I weighed 6.2Kg.

The composition of this chromium-aluminum tanning agent was as follows.

Cr2O37,511% AI. 03 10.81ffi%CHCO
ONa 12.7% by weight MQO 5.4% by weight Basicity 61.7% Example 3 In the same reactor as Example 1, water 2'09
．． 9Kg basic iPi chrome (Neochrome manufactured by Nihon Kagaku Kogyo) 100.0/(g aluminum sulfate (A12 (S04) 357%)
75. el Sodium formate (HCO
ONa95.0%) 21.1/(g) was taken, heated to 60°C, and stirred and mixed for 60 minutes.

31.1 KFI of bicarbonate of soda was gradually added to this mixture over 120 minutes. At this time, the base could be made highly basic without the formation of gel. After the addition, the mixture was filtered according to a conventional method and then spray-dried to obtain 187.9 kg of dried granules. The composition of this granular dry material is Cr2O3 13.5% by weight A1□03 6.8% HCOONa
10.61M%Cr2O3/Al2O3C
II ratio) 2.0 basicity 40.0%, and water solubility was very good.

Calcium carbonate (Ca
Add 11.3 Ny (CO399.0%) and 4°7 Ky of calcined magnesium oxide (Mqo 95.0%) and mix until uniform.Chromium-aluminum tanning agent 2
Passed 03.9Ky.

The composition of this chromium-aluminum tanning agent was as follows.

Cr2O3 12,41% A1□03 6.3% by weight HCOONa
9.81ffi% MqO2,2% by weight CaO3,1% Basicity 65.4% Test Example 1 Chromium-aluminum type produced in Examples 1 to 3 for acid-soaked peel (light steer) 100 weight maximum weight Tanning was carried out in a conventional manner using 7 parts each of tanning agent and Comparative Example 1 on a drum at 20 rpm. At this time, the tanning time was adjusted to 7 hours after the addition of the chromium-aluminum tanning agent, and the temperature of the tanning solution was adjusted to 40°C.

Cr2O3, A1゜03-containing ink, heat shrinkage temperature of the resulting tanned leather, Or in waste water, AI-containing barrier, p
H was as shown in Table 1.

Furthermore, the leather tanned using the chromium-aluminum tanning agents of Practical Mi Examples 1 to 3 was more flexible and had a better grain surface than each of the comparative examples.

Test Example 2 7 parts by weight of Comparative Example 2 was used for 100 parts by weight of pickled leather (light steer), and tanning was carried out using a drum at 2 Orpm. Two hours after the addition of the dried granules, a total of 1.66 parts of sodium bicarbonate was added in three portions every 30 minutes to raise the pH of the tanning solution. The tanning time at this time was adjusted to 7 hours after the addition of the dried granules, and the temperature of the tanning solution was adjusted to 40'C.

Cr2o3 and Al2O3 content Φ of the resulting tanned leather, heat shrinkage temperature and Cr and A'l content in the wastewater,
The pH was as shown in Table 1.

Compared to the example, the work to raise the pH by adding sodium bicarbonate was complicated, and the Cr content in the wastewater was more than double 8 degrees.

<Effects of the Invention> The chromium-aluminum tanning agent of the present invention has the ability to adjust the natural vJ basicity of the tanning bath, so it can omit the complicated pH adjustment of the tanning agent by adding an alkali agent, and
The tanning bath can be easily controlled, and moreover, it penetrates well into the interior of the tanned leather, uniformly distributing chromium and aluminum, and providing a good quality finished leather with flexibility and firmness on the root surface.

In particular, the amount of chromium used can be reduced, and the chromium content in wastewater can be reduced to at least about 115 or less compared to the conventional method, which has the effect of significantly reducing the amount of chromium contamination, making it easier to take environmental measures for wastewater.

Claims (1)

[Claims] (1) (A) Cr_2O_32-25% by weight, Al_2
Contains at least 32 to 25% by weight of O_3 and 1 to 15% by weight of a carboxylic acid compound, with a weight ratio of Cr_2O_3/Al_
It is characterized by mixing 0.2 to 50 parts by weight of a (ro)acid binder to 100 parts by weight of a chromium-aluminum tanning agent having 2O_3 of 0.7 to 3 and basicity of 20 to 55%. Chromium-aluminum tanning agent.