KR101780754B1

KR101780754B1 - Tanning agent for natural leather and manufacturing method thereof using waste MDF

Info

Publication number: KR101780754B1
Application number: KR1020150143443A
Authority: KR
Inventors: 남기두; 조훈호; 강양래; 황진식; 배기한; 조영손; 이병진; 이은정; 신수범; 박민석
Original assignee: 일산실업주식회사; 경남과학기술대학교 산학협력단; 한국신발피혁연구원
Priority date: 2015-10-14
Filing date: 2015-10-14
Publication date: 2017-10-30
Also published as: KR20170043850A

Abstract

The present invention relates to the use of a condensate obtained by condensing lignin sulfonate prepared by treating lignin separated from waste MDF with sodium sulfite and formaldehyde as a natural leather tanning agent and a method of producing the natural leather tanning agent from waste MDF .

Description

Technical Field [0001] The present invention relates to a natural leather tanning agent using waste MDF and a manufacturing method thereof,

Animal hides used as a raw material of natural hides contain many animal tissues and are easily decayed when stored for a long period of time. Accordingly, in the process of processing natural leather as a product, a tanning process is performed in order to prevent the decomposition and decay of the raw hides and to prevent the raw hides from becoming stiff. Examples of the tanning method of natural leather include a vegetable tanning method using a component obtained by extracting leaf or fruit of a plant with salt water, an oil tanning method using an oil extracted from a plant or an animal, and a tanning method using chromium (Cr), zirconium And a mineral tanning method using the same heavy metal component are known. [0004] Among these, the mineral tanning method is known to be effective, but it is pointed out that the use of a heavy metal component lowers the environmental risk and the quality of leather products due to the residual of heavy metals. Therefore, it is urgently required to develop a new tanning agent that can replace the commercialized mineral tanning agent.

On the other hand, MDF (Medium Density Fiberboard), which is called medium density fiber board, is widely used for furniture and building materials. MDF is a plywood made by mixing synthetic fiber adhesives with fibers extracted from wood. It is cheap in cost compared with wood, easy to store, and can be processed into various shapes. As such, the MDF is widely used and the amount of MDF to be disposed of is considerably large. However, it is difficult to recycle waste MDF as industrial material due to its fine fiber structure, so it is classified as whole waste and processed.

Therefore, the inventors of the present invention have studied for many years the recycling of waste DMF as an industrial resource, and as a result, by developing a technique of extracting lignin from waste DMF and using it as raw material for tannin of natural leather, It was completed.

Although lignin has been reported as a by-product in pulp manufacturing process, a technique of using a lignin as a raw material to produce a polymer or derivative and using it as a composite material for an adhesive or a built-in material (see Patent Documents 4 to 6) As a raw material for natural leather tannin has not been reported in any literature to date.

Korean Patent Laid-Open Publication No. 10-2012-0037818 "Method for producing natural leather for furniture" Korean Patent Registration No. 10-0617978 entitled " Method for producing cow-like flesh-like leather using bull horns " Korean Patent Registration No. 10-0706407 entitled " Method for producing environmentally low shrinkage natural leather " Korean Patent Registration No. 10-1526597 entitled "Lignin Polymer, Composite Material for Environmentally Friendly Automobile Interior Materials Using the Same, Korean Patent Registration No. 10-1090532 entitled "Separation and recovery of lignin derivatives" Korean Patent Publication No. 10-0065527 "Method for producing lignin polymer and lignin adhesive using the same"

It is an object of the present invention to provide a natural leather tanning agent using a ligninsulfonic acid salt derived from waste MDF as a raw material.

Another object of the present invention is to provide a method for producing a natural leather tanning agent using lignin sulfonate as a raw material, which is produced through extraction of lignin from waste MDF and sulfonation by sulfurous oxidation.

It is still another object of the present invention to provide natural leather treated by tanning using the natural leather tanning agent.

In order to solve the above-mentioned problems, the present invention relates to a natural leather tannin, which is a condensate of ligninsulfonic acid salt and formaldehyde, and is adjusted to a pH ranging from 5 to 7.

The present invention also relates to a process for producing a natural leather tannin,

a) a step of firstly extracting pulverized MDF pulp with a mixed organic solvent of an alcohol and an aromatic hydrocarbon, followed by secondary extraction with an aqueous sulfuric acid solution to separate lignin solids;

b) reacting the separated lignin with sodium sulfite (NaHSO ₃ ) to prepare a lignin sulfonate;

Step c) Condensation reaction of lignin sulfonate and formaldehyde to prepare a lignin-formaldehyde condensate; And

d) preparing a natural leather tanning agent by adjusting the pH of the lignin-formaldehyde condensate to a range of 5 to 7;

The present invention also provides a method for producing a natural leather tanning agent.

Further, the present invention is characterized by natural leather treated by tanning using the natural leather tanning agent.

The natural leather tannin of the present invention is a plant-derived eco-friendly material produced by using lignin as a raw material. Therefore, the thinning method utilizing the tanning agent of the present invention is environmentally safe in comparison with the conventional mineral tanning method. Particularly, when the lignin is extracted and separated from waste MDF, the present invention is more environmentally friendly in terms of recycling waste resources.

1 is an SEM photograph of pulverized MDF pulverized product.
2 is a photograph of a device used for measuring the heat shrinkage temperature in a liquid.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a plant-derived natural leather tanning agent. The natural leather tannin according to the present invention is a condensate prepared by condensation polymerization of ligninsulfonic acid salt and formaldehyde, and has a weight average molecular weight of 800 to 4,000. In addition, the natural leather tannin of the present invention uses the condensate prepared by the above-mentioned condensation polymerization in the range of pH 5 ~ 7.

While the conventional chromium tanning agent is present as Cr ³ ⁺ cation, the tanning agent of the present invention shows a tanning activity at an acidic condition of pH 3 to 4, while the tanning agent of the present invention has a chemical structural characteristic of a sulfonic acid anion group, Lt; / RTI > Therefore, the tanning process of the present invention can be carried out under neutral conditions, so that it is possible to prevent the quality of the leather product from deteriorating due to the tanning process performed under the acidic condition in the past.

The present invention also includes a method for producing a natural leather tanning agent. A method for producing a natural leather tannin agent according to the present invention comprises:

d) preparing a natural leather tanning agent by adjusting the pH of the lignin-formaldehyde condensate to a range of 5 to 7; .

The process for producing the natural leather tanning agent according to the present invention will be described in more detail as follows.

Step a) is a step of separating lignin from the lung MDF by extraction.

First, the waste MDF is preferably pulverized to an appropriate size (for example, 1 to 10 mm in width and length) so as to facilitate extraction. The extraction according to the present invention comprises a primary extraction process of pulverized MDF pulp with an organic solvent and a secondary extraction process with an aqueous sulfuric acid solution. In the first extraction process, the fatty acid ester component composed of fatty acids and monohydric alcohols can be separated and removed. In the second extraction process, the cellulose dissolved in the aqueous sulfuric acid solution is separated and removed. Through the extraction process, the acid- It can be separated and recovered as a solid component.

In the first extraction process, an organic solvent in which a polar solvent of alcohol and a non-polar solvent of aromatic hydrocarbon are mixed can be used as an extraction solvent. The alcohol may be at least one selected from, for example, methanol, ethanol, and the like. The aromatic hydrocarbon may be at least one selected from benzene, toluene, xylene, and the like. It is preferable that the mixing ratio of alcohol and aromatic hydrocarbon used for lignin extraction is adjusted in a volume ratio range of 1: 1 to 1: 3 in view of extraction efficiency. During the extraction using the above-mentioned organic solvent, it may be heated to a temperature lower than the boiling point of the extraction solvent, if necessary, or it may be extracted under heating at a temperature of 50 to 80 ° C. The primary extraction time using the organic solvent can be adjusted as needed, and it is preferable to proceed for 4 to 6 hours considering economical efficiency.

In the second extraction step, an aqueous sulfuric acid solution is used as an extraction solvent. At this time, the aqueous sulfuric acid solution may be a solution diluted to a concentration of 50 to 80% by weight. The secondary extraction using sulfuric acid aqueous solution can proceed for about 1 to 3 hours, and the acid insoluble lignin in the aqueous sulfuric acid solution can be easily recovered by filtration.

Step b) is a step of sulfonating lignin by a sulfite process.

Specifically, 0.1 to 0.3 parts by weight of sodium sulfite (NaHSO ₃ ) and 5 to 10 parts by weight of an aqueous solvent are reacted at 90 to 130 ° C for 6 to 12 hours based on 1 part by weight of lignin to obtain lignin sulfonate . That is, in step b, a sulfonic acid group is introduced into lignin to effect hydrophilization.

The hydrophilicity of lignin can be controlled by the amount of sodium sulfite, the reaction temperature, and the reaction time. According to the present invention, sodium sulfite is preferably added in an amount of 0.1 to 0.3 parts by weight based on 1 part by weight of lignin. If the amount of the sodium sulfite is less than 0.1 parts by weight, the hydrophilic group can not be sufficiently introduced into the lignin, and even if the amount exceeds 0.3 part by weight, the hydrophilicity of the lignin is not further increased and the economical efficiency is lowered. The reaction temperature is preferably from 90 to 130 ° C. and the reaction time is preferably from 6 to 12 hours. In the reaction conditions described above, the maximum sulfation reaction efficiency is maximized, and the hydrophilization of lignin can be expected. In addition, identification of the production of ligninsulfonate can be confirmed by infrared spectroscopy (FT-IR) in addition to solubility in water.

The ligninsulfonic acid salt prepared by the sulfurous oxidation method is distilled at a temperature of 40 to 60 ° C under a reduced pressure of 60 to 80 cmHg and recovered. The recovered ligninsulfonic acid salt is a liquid polymer having a solid concentration of 20 to 30% by weight &Lt; / RTI >

Step c) is a step of condensing ligninsulfonate and formaldehyde.

Specifically, a lignin-formaldehyde condensate is prepared by reacting 5 to 20 parts by weight of a 35% formaldehyde solution and 1 to 5 parts by weight of an alkali catalyst at 70 to 100 ° C, based on 100 parts by weight of a lignin sulfonate. The alkali catalyst is selected from hydroxides and oxides of an alkali metal or an alkaline earth metal. Specifically, the alkali catalyst is selected from the group consisting of sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) ₂ ), magnesium oxide More than species can be used.

If the amount of formaldehyde used is too small in the condensation reaction of the ligninsulfonic acid salt and formaldehyde, the molecular weight of the condensate may be low and the tanning effect may be reduced. On the other hand, when the amount of formaldehyde used exceeds the above range and is used in an excessive amount, the molecular weight of the condensate is too large to cause a problem in penetration into leather. According to the present invention, the lignin-formaldehyde condensate has a weight average molecular weight ranging from 800 to 4,000, which is suitable for use as a tanning agent of natural leather.

Step d) is a step of adjusting the pH of the lignin-formaldehyde condensate.

The lignin-formaldehyde condensate prepared as a result of the condensation reaction can be applied as a tanning agent for natural leather. However, if the lignin-formaldehyde condensate is subjected to a simple pH control step, the resulting lignin- Can be improved. That is, since the condensation reaction is carried out under the alkaline catalyst condition, the resulting lignin-formaldehyde condensate exhibits a strong alkaline pH of about 9 to 11. Therefore, the pH of the condensate is adjusted to 5 to 7 using an acid solution The effect of improving the heat shrinkage temperature of the liquid in the liquid in the tanning process can be obtained.

The present invention also includes a method for processing natural leather using the above-described lignin-formaldehyde condensate as a tanning agent.

The present invention also encompasses natural leather that has been tanned using a lignin-formaldehyde condensate as a tanning agent.

The tanning process carried out in the present invention is carried out according to a method usually employed in the field of natural leather processing. The tanning process is a process of denaturing animal proteins present in the animal 's hides to minerals and is affected by the content of tanning agents, pH, and time. The tanning agent of the present invention can be added in an amount of 4 to 24 parts by weight based on 100 parts by weight of natural leather. Further, after the addition of 16 parts by weight, no further increase in the heat shrinkage temperature of the liquid can be expected. When the tanning agent of the present invention was used, the leather color showed reddish brown color such as Mimosa and Quebracho, as well as vegetable oiliness agent, and increased convergence. As a result of the experiment according to the tanning process time, the maximum heat shrinkage temperature was measured at 180 minutes. As the time increased, no further increase in heat shrinkage temperature was expected. For the experiment to increase the heat shrinkage temperature, the increase of about 3 ℃ was observed when the oily process was performed overnight.

The present invention will be described in more detail with reference to the following examples, which should not be construed as limiting the scope of the invention.

[Example]

Example 1 Extraction of Lignin from Waste MDF Step

The following extraction procedure was performed using waste MDF to isolate acid insoluble lignin.

That is, the pulverized MDF was pulverized to a width of 1 to 10 mm using a cutting mill, followed by drying at 120 ° C for 1 hour to prepare a waste MDF pulverized product. 1 g of pulverized MDF powder and 20 g of a mixed solvent of methanol and benzene (1: 2) were added to a Soxhlet extractor and extracted at 75 ° C for 6 hours. The fatty acid contained in the pulverized MDF powder and the monohydric alcohol The lead component was removed. 20 g of 72% aqueous H ₂ SO ₄ solution was added to the extracted sample, stirred for 2 hours, and filtered to recover acid-insoluble lignin solids.

The chemical composition and characteristics of the waste MDF analyzed through the extraction process are summarized in Table 1 below.

Chemical composition of lung MDF ingredient Composition (% by weight) How to measure Fatty acid ester 9.8 KS M 7045 Lignin 25.8 KS M 7045 cellulose 52.0 Tappi standard T 9 wd-75 Volatile matter 6.4 KS M 6638 Other ingredients 6.0 KS M 6882

The fatty acid ester components contained in the waste MDF were separated and removed in the first extraction process using an organic solvent, and the cellulose was separated and removed in the second extraction process using an aqueous sulfuric acid solution. In addition, volatile matter and other components were separated and removed in the second extraction and drying process.

As a result, it was possible to obtain lignin as a solid component from waste MDF through the extraction and separation step according to Example 1.

Example 2. Preparation of ligninsulfonic acid salt

30 g of lignin, 300 g of water and 3 to 6 g of sodium sulfite (NaHSO ₃ ) isolated in Example 1 were placed in a reactor equipped with a condenser and the internal temperature of the reactor was raised to 70 to 130 ° C. Sulfite process was performed for 12 hours, and the prepared ligninsulfonate was obtained by concentration under reduced pressure of 70 cmHg until the solid content reached 25% by weight.

Whether the sulfonic acid group was substituted for lignin by the sulfurous oxidation method was confirmed by an infrared spectroscopic analyzer (FT-IR), and the characteristic peak corresponding to the SO ₂ group was confirmed in the region of 1340-1310 cm ^-1 .

In addition, the solubility of the ligninsulfonate prepared according to the conditions (the amount of sodium sulfite used and the reaction temperature adjusted) was measured, and the results are shown in Table 2 below.

[Method for measuring solubility]

Lignin sulfonate was added to water at 25 캜 at a concentration of 10 g / L, and the mixture was stirred and filtered through a filter paper to remove insoluble matter. The filtered sample solution was evaporated under reduced pressure and dried to recover the ligninsulfonic acid salt, and the weight was measured.

Materials Used (parts by weight) Reaction temperature
(° C) Reaction time
(hrs) Solubility (%) of ligninsulfonate Lignin water Sodium sulphate One 10 0.10 110 12 83.6 One 10 0.12 110 12 89.8 One 10 0.14 110 12 93.2 One 10 0.16 110 12 95.4 One 10 0.18 70 12 89.5 One 10 0.18 90 12 93.3 One 10 0.18 110 12 96.0 One 10 0.18 130 12 95.9 One 10 0.20 110 12 96.1

From the above results, it can be seen that the solubility tends to increase as the sodium sulfite content increases and as the reaction temperature increases.

Example 3. Lignin - Formaldehyde Condensate Manufacturing and pH control

300 g of the lignin sulfonate (solid content 25% by weight) prepared in Example 2 and 3 g of sodium hydroxide catalyst were placed in a reactor equipped with a condenser, and the temperature inside the reactor was raised to 90 캜. 15-60 g of 35% formaldehyde solution was then slowly added dropwise over 1 hour. The condensation reaction was carried out at a reaction temperature of 90 占 폚 for 3 hours to obtain a lignin-formaldehyde condensate. When the condensation reaction was completed, a 5% aqueous solution of sulfuric acid was added to the condensate, and the pH of the condensate was neutralized to 5 to 7.

The molecular weight of the resulting condensate was measured and shown in Table 3 below.

Materials Used (parts by weight) The weight average molecular weight Ligninsulfonate Form
Aldehyde NaOH 100 One One 800 100 5 One 1,000 100 10 One 1,500 100 15 One 2,000 100 20 One 3,500 100 25 One 4,000

From the results of Table 3, it was confirmed that the molecular weight of the condensate increases as the amount of formaldehyde used increases.

Experimental Example 1. Tanning process of natural leather

This is an experimental example for confirming the tanning effect when the lignin-formaldehyde condensate of the present invention is applied as a tanning agent of natural leather. The tanning efficiency in this experiment was measured by heat shrinkage temperature in the liquid.

The drum was filled with 150 g of a pH 2.8-3.0 pickling solution and 100 g of leather, and 1.5-2.5 g of sodium bicarbonate was added to the drum in two portions for 10 minutes to give a final pH of 2.8-7.9. Then, 16 g of the condensate prepared in Example 3 was added and the drum was rotated for 3 hours. After draining the solution from the drum, the tanning process was completed by rinsing with water (200 g x 1 time) for 20 minutes.

The test piece for measuring the heat shrinkage temperature in the liquid was prepared by separating a size of 50 mm x 2 mm in a direction of 45 degrees to a beeline and standing for 24 hours in water. When the thickness of the test specimen is less than 3 mm, a load weight of 20 g is applied. When the thickness of the test specimen is 3 mm or more, a weight of 30 g is applied and the water temperature is 3 to 5 ° C / min and the shrinkage starting temperature of the test piece was measured.

The heat shrinkage temperature of each lignin-formaldehyde condensate in the liquid was measured and is shown in Table 4 below.

Lignin-formaldehyde
The weight average molecular weight Tanning
Final pH Liquid weight heat shrinkage temperature
(° C) 800 6.2 59.9 1,000 6.2 63.5 1,500 6.2 63.6 2,000 6.2 63.8 3,500 6.2 62.5 4,000 6.2 62.0 Comparative group
(Bellcotan AS) 4.2 64.0 Comparative group: Aluminum tannin product of NIPPON CHEMICAL Co., Ltd. as a tanning agent commonly used.
Active Ingredient 20-25%

According to Table 4, it can be confirmed that the lignin-formaldehyde condensate of the present invention having a weight average molecular weight ranging from 800 to 4,000 and a pH of from 5 to 7 is effective as a tanning agent.

Claims

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a) a step of firstly extracting pulverized MDF pulp with a mixed organic solvent of an alcohol and an aromatic hydrocarbon, followed by secondary extraction with an aqueous sulfuric acid solution to separate lignin solids;
b) reacting the separated lignin with sodium sulfite (NaHSO ₃ ) to prepare a lignin sulfonate;
Step c) Condensation reaction of lignin sulfonate and formaldehyde to prepare a lignin-formaldehyde condensate; And
d) preparing a natural leather tanning agent by adjusting the pH of the lignin-formaldehyde condensate to a range of 5 to 7;
&Lt; / RTI > characterized in that the tannin is a natural leather.

The method of claim 3,
In the step a), primary extraction is carried out using a mixed solvent of methanol and benzene in a volume ratio of 1: 1 to 1: 3, and secondary extraction is carried out with an aqueous sulfuric acid solution having a concentration of 50 to 80% by weight. Tannin.

The method of claim 3,
(B), 0.1 to 0.3 parts by weight of sodium sulfite (NaHSO ₃ ) and 5 to 10 parts by weight of an aqueous solvent are used at a temperature ranging from 90 to 130 ° C, based on 1 part by weight of lignin, to prepare a natural leather tanning agent Way.

The method of claim 3,
Wherein the ligninsulfonic acid salt prepared in step (b) is a high molecular substance having a solid concentration of 20 to 30% by weight.

The method of claim 3,
Wherein the condensation reaction is carried out at 70 to 100 ° C using 5 to 20 parts by weight of a 35% formaldehyde solution and 1 to 5 parts by weight of an alkali catalyst based on 100 parts by weight of a lignin sulfonate, Tannin.

The method of claim 3,
Wherein the tanning agent prepared in step d) has a weight average molecular weight of 800 to 4,000.

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