A yellowing-resistant and oil-rich fatliquor and its preparation method

Abstract

The present invention belongs to the technical field of fatliquoring agents in leather chemical materials, and discloses a yellowing-resistant and oily fatliquoring agent and a preparation method thereof. The method of the present invention includes dissolving medium- and low-iodine-value vegetable oils in a deep eutectic solvent, and then carrying out an esterification reaction with chloroacetic acid. The prepared fatliquoring agent does not need to add an emulsifier by adjusting the pH to 7-8. In the present invention, the oil is dispersed in the deep eutectic solvent system. At the same time, choline chloride or urea, glycerol, and ethylene glycol in the deep eutectic solvent can enhance the internal plasticity of the fatliquoring agent, and cooperate with the oil molecules to wrap and lubricate leather fibers, and can be applied to the modification of natural oils with medium- and low-iodine values. The fatliquoring agent of the present invention has excellent electrolyte resistance and acid-base stability, good product fluidity, simple operation, and no harmful solvent and waste discharge in the production process. After fatliquoring, the surface of the leather is soft, smooth, and has excellent yellowing and aging resistance performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of fatliquoring agents in leather chemical materials, and particularly relates to a yellowing-resistant and oily fatliquoring agent and a preparation method thereof. Background Art

[0002] Leather fatliquoring is one of the important chemical additives in the leather production process. Treating leather with a fatliquoring agent can endow the leather with softness and good handfeel; it can also make the leather fold-resistant. Leather fatliquoring agents are mainly composed of neutral oil and emulsifying components. Different oil components in the fatliquoring agent result in different styles of leather after fatliquoring treatment. However, at present, the acid, alkali, and salt stability and permeability of leather fatliquoring agents on the market are relatively poor, and their performance is single, unable to meet the requirements of the leather fatliquoring process. Usually, oils with a high iodine value (≥90 g I2 / 100g) are the preferred raw materials for preparing fatliquoring agents due to their easy chemical modification, but they also bring problems such as yellowing of the fatliquored leather, excessive hexavalent chromium, and high fogging value. Therefore, it is urgent to find a suitable method for modifying medium- and low-iodine-value oils to prepare yellowing-resistant fatliquoring agents.

[0003] In view of this, the present invention is specifically proposed. Summary of the Invention

[0004] To solve the problems in the background art, the present invention provides a yellowing-resistant and oily fatliquoring agent and a preparation method thereof. The present invention uses medium- and low-iodine-value vegetable oils as raw materials, and through modification, a fatliquoring agent with good emulsion stability is prepared. This fatliquoring agent can improve the yellowing resistance of leather, and at the same time, it can endow the leather with softness, fullness, moist touch, and good light and heat aging resistance.

[0005] To achieve the above object, the technical solution adopted in this application is as follows:

[0006] A preparation method of a yellowing-resistant and oily fatliquoring agent, which comprises dissolving a medium- and low-iodine-value vegetable oil in a deep eutectic solvent, and then carrying out an esterification reaction with chloro-propionic acid, and adjusting the pH to 7-8.

[0007] Preferably, the deep eutectic solvent is formed by mixing choline chloride and a first component in a molar ratio of 1:(2-6) at 80°C to form a uniform colorless and transparent liquid, and the first component is selected from urea, glycerol, or ethylene glycol.

[0008] Preferably, the medium- and low-iodine-value vegetable oil includes rapeseed oil, palm oil, and coconut oil.

[0009] Preferably, the chloro-propionic acid is 3-chloro-propionic acid or 2-chloro-propionic acid.

[0010] Preferably, the esterification reaction temperature is 90-100°C, and the esterification reaction time is 3-6 h.

[0011] Preferably, the mass ratio of the medium and low iodine value vegetable oil to the deep eutectic solvent is 2:(1 - 2); the mass ratio of the medium and low iodine value vegetable oil to chloroacetic acid is 1:(1 - 3).

[0012] Preferably, adjust to pH 7 - 8 using triethanolamine or ammonia water.

[0013] The present invention also discloses a yellowing - resistant and oil - lubricating fatliquor obtained by the preparation method according to any one of the above.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] Since the medium and low iodine value oil contains abundant hydroxyl groups, when it is dissolved in the deep eutectic solvent, the molecular chains can be better extended and dispersed through hydrogen bonding, and the mixture is easily emulsified in water. There is no need to modify the double bond to increase the hydrophilicity of the medium and low iodine value oil. Therefore, the present invention increases the utilization value of the medium and low iodine value oil; at the same time, to improve the dispersibility of the medium and low iodine value vegetable oil in the deep eutectic solvent system, chloroacetic acid with hydrogen bond donors and acceptors is used to esterify and modify the oil, making the interaction forces between the esterified oil, the deep eutectic solvent and water stronger, and the water emulsibility and stability of the resulting fatliquor are excellent. The leather treated with this fatliquor has good softness and yellowing - resistant stability. At the same time, the fatliquor of the present invention contains highly efficient multifunctional active groups such as carboxyl groups and hydroxyl groups, has good adhesion to leather fibers and is not easily eluted. The surface fatliquoring is soft, smooth, and the light - and heat - resistant properties of the fatliquored leather are excellent. The fatliquor of the present invention has stable performance, good product fluidity, and is convenient to use; it has good water emulsifying ability, and good acid - resistance, alkali - resistance and hard - water resistance stability; when compounded with other fatliquor products, it can help their emulsification and stability.

[0016] The method of the present invention has a simple process, no "three wastes" are discharged during the process, which conforms to the concept of green environmental protection. It improves the difficult application situation of medium and low iodine value vegetable oil in fatliquors. No surfactants are added during the process, and the dispersion function of the deep eutectic solvent, a green solvent, replaces that of the emulsifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is the schematic diagram of the reaction of the deep eutectic solvent and vegetable oil;

[0018] Figure 2 is the schematic diagram of the esterification reaction of vegetable oil dispersed in the deep eutectic solvent with chloroacetic acid;

[0019] Figure 3 is the stability result diagram of the fatliquors of Examples 1 - 3 in different situations during the stability test. DETAILED DESCRIPTION OF THE INVENTION

[0020] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] An embodiment of the present invention provides a preparation method of a yellowing-resistant and oil-rich fatliquor. A low-iodine-value vegetable oil is dissolved in a eutectic solvent, and then subjected to an esterification reaction with chloroacetic acid, and the pH is adjusted to 7-8.

[0022] In the embodiment of the present invention, the oil is dispersed in the eutectic solvent, breaking the requirement for high-iodine-value chemical modification. Vegetable oils with medium and low iodine values can be used as raw materials, and chloroacetic acid is added for esterification to obtain a novel vegetable oil-based fatliquor.

[0023] The reaction mechanism of the embodiment of the present invention is as Figure 1-2 shown. The eutectic solvent is prepared by heating and melting a hydrogen bond donor (glycerol, urea or ethylene glycol) and a hydrogen bond acceptor (choline chloride). Vegetable oils contain multiple hydroxyl groups, and their hydroxyl and ester groups can form hydrogen bond networks with the hydrogen bond donors and acceptors in the eutectic solvent, being dispersed in the eutectic solvent system, which helps to improve the stability of the system against acids, alkalis and salts. Chloroacetic acid is added to modify the vegetable oil. Some of the hydroxyl groups of the oil react with the carboxyl groups of chloroacetic acid, and the free chloroacetic acid forms a hydrogen bond network in the eutectic solvent system, increasing the crosslinking degree of the system, realizing the modification of the vegetable oil, and being used as a fatliquor.

[0024] The embodiment of the present invention can not only realize the modification of high-iodine-value vegetable oils, but also the modification of medium and low-iodine-value vegetable oils. When the medium and low-iodine-value vegetable oil fatliquor obtained by modification is used for fatliquoring leather, it is not easy to oxidize and deepen the color, achieving the effect of yellowing resistance. High-iodine-value vegetable oils generally refer to oils with an iodine value ≥ 90 g I2 / 100g, and medium and low-iodine values refer to oils with an iodine value not exceeding 90 g I2 / 100g. For example, medium and low-iodine-value vegetable oils include rapeseed oil, palm oil and coconut oil.

[0025] The eutectic solvent is a new type of environmentally friendly ionic solvent, which is formed by the combination of hydrogen bond donors (such as glycerol, urea, and ethylene glycol) and hydrogen bond acceptors (such as quaternary ammonium salts and choline chloride). It has the advantages of being biodegradable, non-toxic, low vapor pressure, excellent solubility, and controllability, and is a good extractant and dispersant. Vegetable oils contain polyhydroxyl groups and can be dispersed in the eutectic solvent system. At the same time, the formation of hydrogen bond networks helps to improve the stability of the system against acids, alkalis, and salts. There is no specific limitation on the specific selection of the eutectic solvent, and those skilled in the art can make a choice according to actual needs. In a preferred embodiment, considering the low cost and wide application range, the eutectic solvent is a homogeneous colorless transparent liquid formed by mixing choline chloride and a first component in a molar ratio of 1:2 to 6 at 80 °C, and the first component is selected from urea, glycerol, or ethylene glycol. For the molar ratio of choline chloride to the first component, that is, the dosage of the hydrogen donor and the hydrogen acceptor, directly determines the physical and chemical properties of the eutectic solvent and affects its solubility in oils. Therefore, those skilled in the art can adjust the dosage of choline chloride and the first component according to the different adaptabilities of vegetable oils.

[0026] For the adjustment of the solution pH, common mild basic materials can be used for adjustment, such as triethanolamine, ammonia water, etc.

[0027] The chloroacetic acid is an intermediate that can be used to synthesize organic compounds such as pharmaceuticals, pesticides, and dyes. It contains one hydrogen bond donor and two hydrogen bond acceptors, and can be better dispersed in the eutectic solvent after modifying vegetable oil.

[0028] Example 1

[0029] A preparation method of a yellowing-resistant and oil-rich fatliquor includes the following steps:

[0030] The eutectic solvent is formed by mixing choline chloride-urea in a molar ratio of (1:2) at 80 °C to form a homogeneous colorless transparent liquid. 800 parts by weight of rapeseed oil is dissolved in 400 parts by weight of the eutectic solvent, heated to melt and continuously stirred, and subjected to an esterification reaction with 1000 parts by weight of 2-chloroacetic acid. The esterification reaction temperature is 90 °C, and the esterification reaction time is 6 h. Triethanolamine is added to adjust the pH value to 7 to obtain an oil-rich vegetable oil-based fatliquor.

[0031] Example 2

[0032] A preparation method of a yellowing-resistant and oil-rich fatliquor includes the following steps:

[0033] The eutectic solvent is formed by mixing choline chloride - glycerol in a molar ratio of (1:2) at 80 °C to form a uniform colorless and transparent liquid. 800 parts by weight of coconut oil is dissolved in 400 parts by weight of the eutectic solvent, heated to melt and continuously stirred, and subjected to an esterification reaction with 415 parts by weight of 2 - chloropropionic acid. The esterification reaction temperature is 90 °C and the esterification reaction time is 6 h. Triethanolamine is added to adjust the pH value to 7 to obtain an oily and lubricious vegetable oil - based fatliquor.

[0034] Example 3

[0035] A preparation method of a yellowing - resistant oily and lubricious fatliquor, comprising the following steps:

[0036] The eutectic solvent is formed by mixing choline chloride - ethylene glycol in a molar ratio of (1:2) at 80 °C to form a uniform colorless and transparent liquid. 800 parts by weight of palm oil is dissolved in 400 parts by weight of the eutectic solvent, heated to melt and continuously stirred, and subjected to an esterification reaction with 1100 parts by weight of 2 - chloropropionic acid. The esterification reaction temperature is 90 °C and the esterification reaction time is 6 h. Triethanolamine is added to adjust the pH value to 7 to obtain an oily and lubricious vegetable oil - based fatliquor.

[0037] Example 4

[0038] A preparation method of a yellowing - resistant oily and lubricious fatliquor, comprising the following steps:

[0039] The eutectic solvent is formed by mixing choline chloride - ethylene glycol in a molar ratio of (1:6) at 80 °C to form a uniform colorless and transparent liquid. 400 parts by weight of palm oil is dissolved in 400 parts by weight of the eutectic solvent, heated to melt and continuously stirred, and subjected to an esterification reaction with 400 parts by weight of 2 - chloropropionic acid. The esterification reaction temperature is 95 °C and the esterification reaction time is 4 h. Triethanolamine is added to adjust the pH value to 7 to obtain an oily and lubricious vegetable oil - based fatliquor.

[0040] Example 5

[0041] A preparation method of a yellowing - resistant oily and lubricious fatliquor, comprising the following steps:

[0042] The eutectic solvent is formed by mixing choline chloride - ethylene glycol in a molar ratio of (1:4) at 80 °C to form a uniform colorless and transparent liquid. 800 parts by weight of palm oil is dissolved in 540 parts by weight of the eutectic solvent, heated to melt and continuously stirred, and subjected to an esterification reaction with 1600 parts by weight of 2 - chloropropionic acid. The esterification reaction temperature is 100 °C and the esterification reaction time is 3 h. Triethanolamine is added to adjust the pH value to 8 to obtain an oily and lubricious vegetable oil - based fatliquor.

[0043] Example 6

[0044] A preparation method of a yellowing - resistant oily and lubricious fatliquor, comprising the following steps:

[0045] The eutectic solvent is formed by mixing choline chloride and ethylene glycol at a molar ratio of (1:3) at 80 °C to form a homogeneous colorless transparent liquid. 800 parts by weight of palm oil is dissolved in 600 parts by weight of the eutectic solvent, heated to melt and continuously stirred, and subjected to an esterification reaction with 2400 parts by weight of 2-chloropropionic acid. The esterification reaction temperature is 93 °C and the esterification reaction time is 5 h. Triethanolamine is added to adjust the pH value to 7.5 to obtain an oily vegetable oil-based fatliquor.

[0046] Application examples of fatliquor

[0047] The fatliquors prepared in Examples 1-3 were compared with similar fatliquors for leather fatliquoring under the conditions that they were based on vegetable oil and had the same solid content. The steps were as follows:

[0048] 1) When the yellowing-resistant oily fatliquor prepared in the present invention is used as a leather fatliquor, it can be applied according to Table 1:

[0049] Table 1 Leather fatliquoring process

[0050]

[0051] 。

[0052] 2) Application results

[0053] According to the standard QB / T 2710—2005, specimens were prepared and their mechanical properties such as tensile strength were measured; a TST-E704 yellowing-resistant aging tester was used to test the yellowing-resistant properties of Examples 1-3 and commercially available comparative samples; according to the standard GB / T 22807—2008, reagents were prepared and the hexavalent chromium content in the leather was measured. The application results of the fatliquor of the present invention are shown in Table 2 and Table 3.

[0054] Table 2 Partial quality indexes of fatliquored leather

[0055] 。

[0056] Among them, an oiliness feeling of 3 or less means no oiliness. The higher the score, the better the oiliness feeling, and the full score is 5.0.

[0057] Table 3 Hexavalent chromium indexes of fatliquored leather before and after aging

[0058] 。

[0059] As can be seen from the data in the table, the softness of the fatliquored leather in Example 1, Example 2 and Example 3 is significantly better than that of the commercially available fatliquored leather. The tear strength and tensile strength of the fatliquored leather also indicate that the fatliquoring agent of the present invention has an excellent fatliquoring effect on leather fibers. Because the fatliquoring agent of the present invention has good emulsifying and dispersing properties, the emulsion particle size is small, it is easy to penetrate into the interior of the leather, and the carboxyl and hydroxyl groups on the molecular chain of the fatliquoring agent can complex with Cr(Ⅲ) in the leather, increasing the crosslinking degree between collagen fibers, thereby improving the mechanical properties of the fatliquored leather. The grease wraps the leather fibers, increasing the relative slipperiness between the fibers, making the fatliquored leather soft, smooth and plump. The raw material oil of the fatliquored leather in Example 1, Example 2 and Example 3 has a low iodine value, avoiding the yellowing problem caused by oil oxidation, so the yellowing grades are all higher than those of the commercially available fatliquored leather. It can be seen from Table 3 that the blue wet leather contains trace amounts of Cr(Ⅵ), about 0.31 mg / kg, due to treatments such as shaving and heating. After dyeing and fatliquoring, the Cr(Ⅵ) content of the leather increases slightly. After heat aging and ultraviolet aging, the growth rate of the Cr(Ⅵ) content of the fatliquored leather in Example 1, Example 2 and Example 3 is less than that of the control sample. This is because conventional fatliquoring agents (mainly those containing unsaturated bonds and sulfited fatliquoring agents) contain peroxy groups and are prone to convert Cr(Ⅲ) in chrome-tanned leather into Cr(Ⅵ), while this product uses vegetable oil raw materials with medium and low iodine values and has a low peroxy group content, suppressing the formation of Cr(Ⅵ) from the source.

[0060] Stability test

[0061] The stability of the fatliquoring agents obtained in Examples 1 - 3 was tested under different conditions. The specific test methods are as follows:

[0062] ① 1:9 dilution stability: Take 90 mL of hot distilled water at 55 - 60 °C in a 100 mL stoppered graduated cylinder, add 10 mL of the sample, tightly stopper the bottle, turn it up and down for 1 min (about 30 times) to mix well, and then let it stand at 25 - 35 °C for 24 h. Observe the layering situation to examine the stability of the solution.

[0063] ② Determination of the stability to 10% quebracho extract solution: Take 80 mL of hot distilled water at 55 - 60 °C in a 100 mL stoppered graduated cylinder, add 10 mL of the sample and 10 mL of 10% myrica quebracho extract solution, tightly stopper the bottle, turn it up and down for 1 min (about 30 times) to mix well, and then let it stand in a constant temperature water bath at 25 - 35 °C for 4 h. Observe the layering situation to examine the stability of the solution.

[0064] ③ Determination of the stability of 10% potassium chromic sulfate solution: Take 80 mL of hot distilled water at 55 - 60 °C in a 100 mL stoppered graduated cylinder, add 10 mL of the sample, tightly stopper the bottle, shake well, then add 10 mL of 10% potassium chromic sulfate solution, turn it up and down for 1 min (about 30 times), shake well, and let it stand in a constant temperature water bath at 25 - 35 °C for 4 h. Observe the layering situation to examine the stability of the solution.

[0065] ④ Determination of the stability of 1 mol / L hydrochloric acid solution: Take 80 mL of hot distilled water at 55 - 60 °C in a 100 mL stoppered graduated cylinder, add 10 mL of the sample, tightly stopper the bottle, shake well, then add 10 mL of 1 mol / L hydrochloric acid solution, turn it up and down for 1 min (about 30 times), shake well, and let it stand in a constant temperature water bath at 25 - 35 °C for 4 h. Observe the layering situation to examine the stability of the solution.

[0066] ⑤ Determination of the stability of 1 mol / L ammonium hydroxide solution: Take 80 mL of hot distilled water at 55 - 60 °C in a 100 mL stoppered graduated cylinder, add 10 mL of the sample, tightly stopper the bottle, shake well, then add 10 mL of 1 mol / L ammonium hydroxide solution, turn it up and down for 1 min (about 30 times), shake well, and let it stand in a constant temperature water bath at 25 - 35 °C for 4 h. Observe the layering situation to examine the stability of the solution.

[0067] The test results are as Figure 3 shown, Figure 3 the numbers on each test tube in Figure 3 correspond to the stability test conditions in the above different situations. It can be seen from

[0068] that there is no layering phenomenon in each test tube, indicating that the fatliquor prepared by the present invention has good dilution stability, acid, alkali, and chromium resistance stability. The preparation method of a yellowing-resistant and oil-rich fatliquor provided by the present invention is introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The above description of the implementation is only applicable to helping understand the method and core idea of the present invention. It should be noted that any person skilled in the art within the technical scope disclosed by the present invention can easily think of substitutions and changes, which should be covered within the protection scope of the present invention.

Claims

1. A preparation method of a yellowing-resistant and oil-rich fatliquor, characterized in that, Dissolve medium- and low-iodine-value vegetable oil in a deep eutectic solvent, and then carry out an esterification reaction with chloroacetic acid, adjusting the pH to 7-8; The deep eutectic solvent is a homogeneous colorless transparent liquid formed by mixing choline chloride with a first component, and the first component is selected from urea, glycerol or ethylene glycol; The molar ratio of the medium- and low-iodine-value vegetable oil to chloroacetic acid is 1:(1-3); The iodine value of the medium- and low-iodine-value vegetable oil does not exceed 90 g I2 / 100g.

2. The preparation method according to claim 1, wherein, Choline chloride and the first component are mixed at a molar ratio of 1:(2-6) at 75-80 °C.

3. The preparation method according to claim 1, characterized in that, The chloroacetic acid is 3-chloroacetic acid or 2-chloroacetic acid.

4. The preparation method according to claim 1, characterized in that, The esterification reaction temperature is 90-100 °C, and the esterification reaction time is 3-6 h.

5. The preparation method according to claim 1, characterized in that The mass ratio of the medium- and low-iodine-value vegetable oil to the deep eutectic solvent is 2:(1-2).

6. The preparation method according to claim 1, characterized in that, Adjust to pH 7-8 using triethanolamine or ammonia water.

7. A yellowing-resistant oily fatliquoring agent obtained by the preparation method according to any one of claims 1-6.

8. Use of the yellowing-resistant oily fatliquoring agent according to claim 7 as a leather fatliquoring agent.

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