WO2009105962A1

WO2009105962A1 - Leather tanning process based on the recycling of poly hydroxyl alkyl phosphine and its derivatives

Info

Publication number: WO2009105962A1
Application number: PCT/CN2009/000192
Authority: WO
Inventors: Yingyong Yang
Original assignee: Rhodia Hengchang Zhangjiagang Specialty Chemical Co Ltd
Current assignee: Solvay Hengchang Zhangjiagang Specialty Chemical Co Ltd
Priority date: 2008-02-26
Filing date: 2009-02-24
Publication date: 2009-09-03
Anticipated expiration: 2010-08-26
Also published as: AU2009218971B2; NZ587313A; CN101965411B; AU2009218971A1; CN101965411A; CN101519701A

Abstract

This invention relates to a leather tanning process based on the recycling of poly hydroxyl alkyl phosphine and its derivatives comprising the preparation of the tanning initial liquid of tanning agent based on poly hydroxyl alkyl phosphine and its derivatives, the recycling of poly hydroxyl alkyl phosphine and its derivatives to the tanning process, and the adjustment of the residual liquid of tanning agent, pH, stabilizer and buffer agent, and the guarantee that the leather tanning quality is unchanged, as well as the repetition that allows unlimited use of the bath liquid without the discharge of waste water.

Description

LEATHER TANNING PROCESS BASED ON THE RECYCLING OF POLY HYDROXYL ALKYL PHOSPHINE AND ITS DERIVATIVES

Technical Field This invention relates to a Leather Tanning process based on the recycling of

Poly Hydroxyl Alkyl Phosphine and its Derivatives in order to promote environmental protection.

Background Leather industry is one of the heavy pollution industries. The work procedure of leather tanning is especially polluting, because tanning agents are mostly toxic, hazardous chemicals. Metal tanning agents, in particular chromium tanning agents, have become the most important chemicals for leather tanning at present. The consumption of base type chromium sulfate as tanning agent is up to 22,000-27,000 ton (converted to equivalent dichromate) every year. About half of these heavy metals are discharged (part of which is treated for landfill). The part combined and absorbed by leather products enters the environment after the leather products become wastes. Because chromium sulfate is highly prone to convert to dichromate, chromium tanning agent has become the top pollutant chemical in leather manufacturing industry. In order to minimize the discharge of chromium tanning agent, scientists have done wide-ranging and in-depth studies. Duan Zheηji et al. have studied on PCPA (2-propenoic acid resin) tanning auxiliary agent and have increased the absorption of chromium tanning agent to decrease the use of chromium tanning agent. Zhang Mingrang et al. have studied on high-absorption chromium tanning agents and have obtained excellent results in the technology of increasing the utilization rate of chromium tanning agent. However, they is still a need to fundamentally remove the harm of chromium tanning agent from the environment and the potential hazard to human body. In the mean time, many scientists have studied on the recycle technology of chromium tanning waste liquid. But due to various technical factors, it is difficult for the technology to be publicized in industrial production. Aldehyde tanning agent is another widely-used organic tanning agent. Methyl aldehyde was once widely used in fur and pelt industry. However, due to its high volatility, toxicity and hazardous nature, it has been strictly prohibited from use in China. Pentane dialdehyde and its derivatives 5 have unique tanning characteristics. At present, they are still tanning agents frequently used in leather industry. However, the harm of pentane dialdehyde and its derivatives to the environment and human body still exists. Oxazolidine is a new type of organic tanning agent, on which in-depth studies have been done by Dow Chemical Co. a US company. However, its recycle utilization is yet to be reported or disclosed. Using plant i o tanning agent to tan leather is a superior environmental protection technology. It allows complete recycle utilization. However, due to its specific leather tanning features, single tanning can only meet the demand of a small part of leathers. Poly hydroxyl alkyl phosphine, along with its derivatives as well as composite products, is a new type of organic tanning agent, featuring its superior tanning function. However, no tanning

15 agent can be completely absorbed by the leather. In the mean time, tanning residual liquid contains a large amount of substances such as edible salt etc. unabsorbed by the leather. If these substances are discharged, not only they cause great harm to the environment, but it is also a huge waste of materials. 0 Invention Details

The objective of this invention is to provide a leather tanning process allowing to recycle the poly hydroxyl alkyl phosphine and its derivatives in order to save energy and decrease environmental pollution in the leather tanning industry.

Thus, the instant invention relates to a leather tanning process comprising the 5 steps of:

A) - preparing a tanning initial liquid of tanning agent made of poly hydroxyl alkyl phosphine and its derivatives:

- adding a stabilizer to the tanning initial liquid; said stabilizer is a mixture that contains surface active agent, poly hydroxyl compound, phosphate salt, preservatives, in an amount of 0.1-2% of pickling skin weight or 0.1-3 gram/liter of tanning bath liquid;

- adding a buffer agent to the tanning initial liquid, in an amount of 0.1-3% of pickling skin weight or 0.1-3 gram/liter of tanning bath liquid; wherein the tanning initial liquid contains at least one type of poly hydroxyl alkyl phosphine and its derivatives in a concentration of 0.4-5.0% of pickling skin weight, preferably 1.0-5.0% of pickling skin weight, or 0.4-7 gram/liter of tanning bath liquid, preferably 1-7 gram/liter of tanning bath liquid; and

B) - adding the tanning initial liquid to the pickling skin, the skin being rotated 90-360 degrees, and adding alkali successively to increase the pH of the bath liquid gradually to 5-7, the skin being again rotated 60-360 degrees and taken out, after tanning is completed,

- washing the skin with water, and performing the routine post-tanning step, the concentration of the poly hydroxyl alkyl phosphine and its derivatives in the residual liquid being measured through iodine titration solution by using micro titration test chamber, analyzed and adjusted to the initial tanning agent content, and -ajusting the pH with acidic matter(s) between 3-5; and

C) - adding 0-50% of the stabilizer and the buffer agent in step A) to the aforesaid adjusted tanning bath liquid, the residual liquid of the completely adjusted mixture of tanning agent stabilizer and buffer agent being recycling batchwise or continuously.

Preferably, the surface active agent is dodecyl alcohol polyoxyethylene 9 ether.

Preferably, the poly hydroxyl compound is white sugar, polyvinyl alcohol, and polyethylene glycol. Preferably, the phosphate salt is ortho-phosphate salt, pyro-phosphate salt, meta-phosphate salt, or hydrophosphate salt or the derivatives thereof.

Preferably, the buffer agent is a mixture of methanoic acid, ethanoic acid and its strong alkaline salt.

Preferably, the buffer agent is the mixture of methanoic acid and sodium ethanoate.

Preferably, the poly hydroxyl alkyl phosphine and its derivatives are tetra hydroxyl methyl phosphorus chloride and its polymer with urine, tetra hydroxyl ethyl phosphorus chloride and its polymer with urine, tetra hydroxyl propyl phosphorus chloride and its polymer with urine, tetra hydroxyl n-butyl phosphorus chloride and its polymer with urine, tetra hydroxyl n-pentyl phosphorus chloride and its polymer with urine, tetra hydroxyl methyl phosphorus sulfate and its polymer with urine, and/or tetra hydroxyl ethyl phosphorus sulfate and its polymer with urine.

Preferably, the acidic matter is ammonia sulfate, methanoic acid, acetic acid, lactic acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, or a mixture thereof.

The leather tanning process of this invention comprises more particularly the following steps:

A) Preparation of the tanning initial liquid of tanning agent made of poly hydroxyl alkyl phosphine and its derivatives:

1 ) A stabilizer is added to the tanning initial liquid. In particular, the stabilizer is a mixture that contains surface active agent, poly hydroxyl compound, phosphate salt, preservatives etc. Its amount of use is calculated at

0.1-2% of pickling skin weight or 0.1-3 gram/liter of tanning bath liquid. 2 ) The tanning initial liquid is added with a buffer agent. Its amount of use is 0.1-3% of pickling skin weight or 0.1-3 gram/liter of tanning bath liquid.

3 ) The tanning initial liquid contains one type or many types of poly hydroxyl alkyl phosphine and its derivatives. The concentration is 0.4-5.0% of pickling skin weight, preferably 1.0-5.0% of pickling skin weight, or 0.4-7 gram/liter of tanning bath liquid, preferably 1-7 gram/liter of tanning bath liquid.

B. Recycle tanning utilization of the poly hydroxyl alkyl phosphine and its derivatives:

The tanning initial liquid is added with pickling skin. The skin is rotated 90-360 degrees, and is added with alkali successively, to increase the pH of the bath liquid gradually to 5-7. The skin is again rotated 60-360 degrees. The skin is taken out. After tanning is completed, the skin is washed by water, and enters the routine post-tanning step. The concentration of the poly hydroxyl alkyl phosphine and its derivatives in the residual liquid is measured through iodine titration solution by using micro titration test chamber, and analyzed and adjusted to the initial tanning agent content. The pH is adjusted with acidic matter(s) to between 3-5.

C. The bath liquid of the aforesaid adjusted tanning agent and pH is added with

0-1/2 of stabilizer and buffer agent mentioned in step A. The residual liquid of the completely adjusted tanning agent, pH, stabilizer and buffer agent can be use continuously, and the leather tanning quality is unchanged. If the step is repeated, the objective of unlimited use of the bath liquid can be met.

In particular, the surface active agent can be dodecyl alcohol polyoxyethylene (9) ether (AEO-9) or other. The poly hydroxyl compound can be white sugar, polyvinyl alcohol, polyethylene glycol etc. The phosphate salt can be ortho-phosphate salt, pyro-phosphate salt, meta-phosphate salt, hydrophosphate salt and its derivatives.

In particular, the buffer agent can be the mixture of methanoic acid, ethanoic acid and its strong alkaline sale, e.g. the mixture of methanoic acid and sodium formate.

In particular, the poly hydroxyl alkyl phosphine and its derivatives are tetra hydroxyl methyl phosphorus chloride and its polymer with urine, tetra hydroxyl ethyl phosphorus chloride and its polymer with urine, tetra hydroxyl propyl phosphorus chloride and its polymer with urine, tetra hydroxyl n-butyl phosphorus chloride and its polymer with urine, tetra hydroxyl n-pentyl phosphorus chloride and its polymer with urine, tetra hydroxyl methyl phosphorus sulfate and its polymer with urine, and/or tetra hydroxyl ethyl phosphorus sulfate and its polymer with urine.

In particular, the utilization acidic matter can be one or several of ammonia sulfate, methanoic acid, acetic acid, lactic acid, hydrochloric acid, sulfuric acid, nitric acid, and phosphoric acid.

As compared to the existing technology, the technology of this invention enables the tanning bath liquid to be recycled and utilized for unlimited times, without the discharge of waste water. In addition, the technique is simple, the temperature is low, and the energy consumption is low. It saves energy and protects the environment. It is easy to control. It is easy to supervise the entire process of production. The stability and consistency of the product is guaranteed.

Embodiment of the Present Invention

Further explanation of this invention with reference to embodiments is given below Example 1 : Recycle Utilization Technology of Poly Hydroxyl Alkyl Phosphine and its Derivatives in the Application of Leather Tanning

1. Preparation of tanning initial liquid of tanning agent made of poly hydroxyl alkyl phosphine and its derivatives:

The tanning initial liquid is added with a stabilizer, i.e. a mixture of dodecyl alcohol polyoxyethylene (9) ether (AEO-9), white sugar, pyro-phosphate salt, preservatives etc. Its amount of use is 0.1 of pickling skin weight. The tanning initial liquid is added with a buffer agent, i.e. a mixture of methanoic acid and sodium methanoate. Its amount of use is 3% of pickling skin weight. The tanning initial liquid contains tetra hydroxyl methyl phosphorus chloride and its polymer with urine, at the concentration of 1 % of pickling skin weight.

2. Recycle tanning utilization of the poly hydroxyl alkyl phosphine and its derivatives:

The tanning initial liquid is added with pickling skin. The skin is rotated 360 degrees, and is added with alkali successively, to increase the pH of the bath liquid gradually to 5-7. The skin is again rotated 60 degrees. The skin is taken out. After tanning is completed, the skin is washed by water, and enters the routine post-tanning step. The concentration of the poly hydroxyl alkyl phosphine and its derivatives in the residual liquid is measured through iodine titration solution by using micro titration test chamber, and analyzed and adjusted to the initial tanning agent content. The pH is adjusted with acidic matter(s) to between 3-5.

3. The bath liquid of the aforesaid adjusted tanning agent and pH is added with

1/2 of stabilizer and buffer agent mentioned in step 1. The residual liquid of the completely adjusted tanning agent, pH, stabilizer and buffer agent can be use

5 continuously, and the leather tanning quality is unchanged. If the step is repeated, the objective of unlimited use of the bath liquid can be met.

Example 2: Recycle Utilization Technology of Poly Hydroxyl Alkyl Phosphine and its Derivatives in the Application of Leather Tanning

1. Preparation of tanning initial liquid of tanning agent made of poly hydroxyl i o alkyl phosphine and its derivatives:

The tanning initial liquid is added with a stabilizer, i.e. a mixture of dodecyl alcohol polyoxyethylene (9) ether (AEO-9), polyvinyl alcohol, ortho-phosphate salt, preservatives etc. Its amount of use is 2% of pickling skin weight. The tanning initial liquid is added with a buffer agent, i.e. a mixture of methanoic acid and sodium 15 methanoate. Its amount of use is 0.1% of pickling skin weight. The tanning initial liquid contains tetra hydroxyl propyl phosphorus chloride and its polymer with urine, at the concentration of 5% of pickling skin weight.

2. Recycle tanning utilization of the poly hydroxyl alkyl phosphine and its derivatives: 0 The tanning initial liquid is added with pickling skin. The skin is rotated 90 degrees, and is added with alkali successively, to increase the pH of the bath liquid gradually to 5-7. The skin is again rotated 360 degrees. The skin is taken out. After tanning is completed, the skin is washed by water, and enters the routine post-tanning step. The concentration of the poly hydroxyl alkyl phosphine and its derivatives in the 5 residual liquid is measured through iodine titration solution by using micro titration test chamber, and analyzed and adjusted to the initial tanning agent content. The utilization acidic matter pH is adjusted to between 3-5.

3. The residual liquid of the completely adjusted tanning agent can be use continuously, and it is guaranteed that the leather tanning quality is unchanged. If the step is repeated, the objective of unlimited use of the bath liquid can be met.

Example 3: Recycle Utilization Technology of Poly Hydroxyl Alkyl Phosphine and its Derivatives in the Application of Leather Tanning

The tanning initial liquid is added with a stabilizer, i.e. a mixture of dodecyl alcohol polyoxyethylene (9) ether (AEO-9), polyethylene glycol, meta-phosphate salt, preservatives etc. Its amount of use is 1% of pickling skin weight. The tanning initial liquid is added with a buffer agent. Its amount of use is 0.1% of pickling skin weight. The tanning initial liquid contains terra hydroxyl ethyl phosphorus chloride and its polymer with urine, at the concentration of 3% of pickling skin weight.

The tanning initial liquid is added with pickling skin. The skin is rotated 230 degrees, and is added with alkali successively, to increase the pH of the bath liquid gradually to 5-7. The skin is again rotated 210 degrees. The skin is taken out. After tanning is completed, the skin is washed by water, and enters the routine post-tanning step. The concentration of the poly hydroxyl alkyl phosphine and its derivatives in the residual liquid is measured through iodine titration solution by using micro titration test chamber, and analyzed and adjusted to the initial tanning agent content. The utilization acidic matter pH is adjusted to between 3-5.

3. The bath liquid of the aforesaid adjusted tanning agent and pH is added with 1/4 of stabilizer and buffer agent mentioned in step 1. The residual liquid of the completely adjusted tanning agent, pH, stabilizer and buffer agent can be use continuously, and it is guaranteed that the leather tanning quality is unchanged. If the step is repeated, the objective of unlimited use of the bath liquid can be met.

Example 4: Recycle Utilization Technology of Poly Hydroxyl Alkyl Phosphine and its Derivatives in the Application of Leather Tanning

The tanning initial liquid is added with a stabilizer, i.e. a mixture of dodecyl alcohol polyoxyethylene (9) ether (AEO-9), white sugar, hydrophosphate salt, preservatives etc. Its amount of use is 0.1 gram/liter of tanning bath liquid. The tanning initial liquid is added with a buffer agent, i.e. a mixture of methanoic acid and sodium methanoate. Its amount of use is 3 gram/liter of pickling skin weight. The tanning initial liquid contains terra hydroxyl butyl phosphorus chloride and its polymer with urine, at the concentration of 3 gram/liter of pickling skin weight.

The tanning initial liquid is added with pickling skin. The skin is rotated 360 degrees, and is added with alkali successively, to increase the pH of the bath liquid gradually to 5-7. The skin is again rotated 60 degrees. The skin is taken out. After tanning is completed, the skin is washed by water, and enters the routine post-tanning step. The concentration of the poly hydroxyl alkyl phosphine and its derivatives in the residual liquid is measured through iodine titration solution by using micro titration test chamber, and analyzed and adjusted to the initial tanning agent content. The utilization acidic matter pH is adjusted to between 3-5.

Example 5: Recycle Utilization Technology of Poly Hydroxyl Alkyl Phosphine and its Derivatives in the Application of Leather Tanning

The tanning initial liquid is added with a stabilizer, i.e. a mixture of dodecyl alcohol polyoxyethylene (9) ether (AEO-9), polyvinyl ethanol, ortho-phosphate salt, pyro-phosphate salt and preservatives etc. Its amount of use is 3 gram/liter of tanning bath liquid. The tanning initial liquid is added with a buffer agent, i.e. a mixture of methanoic acid and sodium methanoate. Its amount of use is 0.1 gram/liter of pickling skin weight. The tanning initial liquid contains terra hydroxy! n-propyl phosphorus chloride and its polymer with urine, at the concentration of 7 gram/liter of pickling skin weight.

The tanning initial liquid is added with pickling skin. The skin is rotated 90 degrees, and is added with alkali successively, to increase the pH of the bath liquid gradually to 5-7. The skin is again rotated 360 degrees. The skin is taken out. After tanning is completed, the skin is washed by water, and enters the routine post-tanning step. The concentration of the poly hydroxyl alkyl phosphine and its derivatives in the residual liquid is measured through iodine titration solution by using micro titration test chamber, and analyzed and adjusted to the initial tanning agent content. The utilization acidic matter pH is adjusted to between 3-5.

3. The aforesaid completely adjusted residual liquid can be use continuously, and it is guaranteed that the leather tanning quality is unchanged. If the step is repeated, the objective of unlimited use of the bath liquid can be met. Example 6: Recycle Utilization Technology of Poly Hydroxyl Alkyl Phosphine and its Derivatives in the Application of Leather Tanning

The tanning initial liquid is added with a stabilizer, i.e. a mixture of dodecyl alcohol polyoxyethylene (9) ether (AEO-9), polyvinyl ethanol, polyethylene glycol, pyro-phosphate salt, and preservatives etc. Its amount of use is 1.5 gram/liter of tanning bath liquid. The tanning initial liquid is added with a buffer agent, i.e. a mixture of methanoic acid and sodium methanoate. Its amount of use is 1.6 gram/liter of pickling skin weight. The tanning initial liquid contains terra hydroxyl methyl phosphorus chloride and its polymer with urine, as well as tetra hydroxy! methyl phosphorus sulfate, at the concentration of 7 gram/liter of pickling skin weight.

5 The tanning initial liquid is added with pickling skin. The skin is rotated 220 degrees, and is added with alkali successively, to increase the pH of the bath liquid gradually to 5-7. The skin is again rotated 210 degrees. The skin is taken out. After tanning is completed, the skin is washed by water, and enters the routine post-tanning step. The concentration of the poly hydroxyl alkyl phosphine and its derivatives in the i o residual liquid is measured through iodine titration solution by using micro titration test chamber, and analyzed and adjusted to the initial tanning agent content. The utilization acidic matter pH is adjusted to between 3-5.

3. The bath liquid of the aforesaid adjusted tanning agent and pH is added with 1/4 of stabilizer and buffer agent mentioned in step 1. The residual liquid of the

15 completely adjusted tanning agent, pH, stabilizer and buffer agent can be use continuously, and it is guaranteed that the leather tanning quality is unchanged. If the step is repeated, the objective of unlimited use of the bath liquid can be met.

Claims

CLAIMS OF THE INVENTION

What is claimed:

L A leather tanning process comprising the steps of:

- adding a buffer agent to the tanning initial liquid in an amount of 0.1-3% of pickling skin weight and 0.1-3 gram/liter of tanning bath liquid; wherein the tanning initial liquid contains at least one type of poly hydroxyl alkyl phosphine and its derivatives in a concentration of 0.4-5.0% of pickling skin weight, preferably 1.0-5.0% of pickling skin weight, or 0.4-7 gram/liter of tanning bath liquid, preferably 1-7 gram/liter of tanning bath liquid; and

B) - adding the pickling skin to the tanning initial liquid, the skin being rotated 90-360 degrees, and adding alkali successively to increase the pH of the bath liquid gradually to 5-7, the skin being again rotated 60-360 degrees and taken out, after tanning is completed,

2. The leather tanning process as claimed in claim 1, characterized in that the surface active agent is dodecyl alcohol polyoxyethylene 9 ether.

5 3. The leather tanning process as claimed in claim 1 , characterized in that the poly hydroxyl compound is white sugar, polyvinyl alcohol, and polyethylene glycol.

4. The leather tanning process as claimed in claim 1, characterized in that the phosphate salt is ortho-phosphate salt, pyro-phosphate salt, meta-phosphate salt, or i o hydrophosphate salt or the derivatives thereof.

5. The leather tanning process as claimed in claim 1, characterized in that the buffer agent is a mixture of methanoic acid, ethanoic acid and its strong alkaline salt.

15 6. The leather tanning process as claimed in claim 1, characterized in that the buffer agent is the mixture of methanoic acid and sodium ethanoate.

7. The leather tanning process as claimed in claim 1 , characterized in that the poly hydroxyl alkyl phosphine and its derivatives are terra hydroxyl methyl phosphorus

20 chloride and its polymer with urine, tetra hydroxyl ethyl phosphorus chloride and its polymer with urine, tetra hydroxyl propyl phosphorus chloride and its polymer with urine, tetra hydroxyl n-butyl phosphorus chloride and its polymer with urine, tetra hydroxyl n-pentyl phosphorus chloride and its polymer with urine, tetra hydroxyl methyl phosphorus sulfate and its polymer with urine, and/or tetra hydroxyl ethyl

25 phosphorus sulfate and its polymer with urine.

8. The leather tanning process as claimed in claim 1, characterized in that the acidic matter is ammonia sulfate, methanoic acid, acetic acid, lactic acid, hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, or a mixture thereof.