A method for preparing a modified rapeseed oil softening agent

Abstract

The present application relates to the field of cultural relic protection, and discloses a preparation method of modified rapeseed oil leather softening agent. The present application takes rapeseed oil as the main raw material of the leather softening agent, first carries out alcoholysis reaction with methanol to introduce excess hydroxyl groups, which can not only reduce the molecular weight and viscosity of the rapeseed oil (favorable to the penetration of the softening agent into the inside of the leather), but also enable the rapeseed oil to further react as an intermediate; on this basis, continues to use hydrogen peroxide to oxidize the carbon-carbon double bond in the rapeseed oil to form an epoxy structure, which can improve the antioxidant stability of the rapeseed oil; further, sulfites the rapeseed oil, introduces sulfonic acid groups on the molecule, which can significantly enhance the water solubility and has good self-emulsifying performance. Therefore, the final obtained leather softening agent has excellent permeability and emulsion stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cultural relic protection, and particularly relates to a preparation method of modified rapeseed oil leather softening agent. BACKGROUND

[0002] Leather products are closely related to human civilization and social development, and its application is not only limited to clothing and other daily necessities, but also includes applications in transportation, military, culture and art, etc. A large number of unearthed or handed down leather-made cultural relics have important value for substantiating Chinese civilization. Since the main component of leather, protein, is easily affected by adverse factors such as microorganisms, light, heat, acid and alkali and thus degrades, leather cultural relics are difficult to be preserved, and therefore the quantity of unearthed leather-made cultural relics is relatively small. Compared with other types of organic cultural relics, leather-made cultural relics are more difficult to protect due to the use of various materials, complex tanning process and unknown degradation mechanism.

[0003] Existing leather-made cultural relics have diseases such as dryness, discoloration, hardening, decay and mildew, which endanger the long-term preservation of leather-made cultural relics. Softening agents are a kind of preparations that can lubricate the fiber organization of leather, so that the leather has certain toughness, softness, mechanical strength and ductility. In the softening process of leather cultural relics, the softening agent first emulsifies the surface of the leather through emulsification, then diffuses into the leather, uniformly distributes on the surface of the fibers in the leather, continuously penetrates inward, and finally fills in the collagen fibers and the gaps therebetween, so that the leather cultural relics become soft.

[0004] However, since the leather cultural relics are in a long-term dehydrated and hardened state, the combination between the collagen fibers in the leather cultural relics is more compact compared with ordinary leather products, which causes the currently used leather softening agent to be difficult to fully penetrate into the interior of the leather cultural relics, and therefore the softening effect is generally not ideal. SUMMARY

[0005] In order to solve the above technical problems, the present application provides a preparation method of modified rapeseed oil leather softening agent. In the present application, rapeseed oil is used as the main raw material of the leather softening agent. First, the rapeseed oil is subjected to alcoholysis reaction with methanol to introduce excess hydroxyl groups, which not only can reduce the molecular weight and viscosity of the rapeseed oil (which is conducive to the penetration of the softening agent into the interior of the leather), but also can make the rapeseed oil as an intermediate to undergo other reactions; on this basis, the carbon-carbon double bond in the rapeseed oil is oxidized to form an epoxy structure by using hydrogen peroxide, which can improve the antioxidant stability of the rapeseed oil; further, the rapeseed oil is subjected to sulfurous acid modification to introduce sulfonic acid groups on the molecule, which can significantly enhance the water solubility and has good self-emulsifying performance. Therefore, the finally obtained leather softening agent has excellent permeability and emulsion stability.

[0006] The specific technical scheme of the present application is as follows: a preparation method of modified rapeseed oil leather softening agent, comprising the following steps:

[0007] 1) Mix the rapeseed oil and methanol uniformly, add catalyst sodium methoxide; stir and reflux at 60-65℃, carry out alcoholysis reaction under inert atmosphere; the mass ratio of methanol and rapeseed oil is 3-4:1.

[0008] 2) After the reaction is completed, distill under reduced pressure to recover the excess methanol, and let the reaction product stand to separate the upper oil layer to obtain the alcoholysis rapeseed oil.

[0009] 3) Mix the alcoholysis rapeseed oil, acetic acid and catalyst, stir and heat to 50-56℃, and add hydrogen peroxide (30%) dropwise to the system to carry out the reaction. The amount of acetic acid is 7-11% of the mass of the alcoholysis rapeseed oil; and the amount of hydrogen peroxide (25-35wt%) is 40-45% of the mass of the alcoholysis rapeseed oil.

[0010] 4) Add alkali to the reaction system to neutralize, let stand, and remove the water layer after the layers are separated.

[0011] 5) Wash the product obtained in step 4) with water, let stand, and remove the water layer to obtain the epoxidized modified rapeseed oil.

[0012] 6) Heat the epoxidized modified rapeseed oil to 50-60℃, and slowly add sodium bisulfite aqueous solution dropwise to carry out the reaction; the amount of sodium bisulfite is 20-30% of the mass of the epoxidized modified rapeseed oil.

[0013] 7) Add 1-3wt% of sodium dodecyl sulfonate to the system of step 6), heat to 80-90℃ and stir uniformly to obtain the modified rapeseed oil leather softener.

[0014] The rapeseed oil is an eco-friendly material and is easy to degrade. The present application finds that it can have good filling property for leather as the main raw material of the leather softener. However, the rapeseed oil has the disadvantage that there are less functional groups in the molecular structure that can be firmly combined with collagen fibers. Therefore, the present application solves the above problems by chemical modification, first introducing hydroxyl groups into the rapeseed oil molecules and reducing the molecular weight of the rapeseed oil, and then performing epoxidation modification. The epoxidized oil is a three-membered ring compound, has high reactivity, and has good self-emulsifying ability after sodium sulfite is introduced by sodium bisulfite, thereby solving the above problems.

[0015] In step 1), the present application modifies the rapeseed oil by introducing excess hydroxyl groups, which not only can reduce the molecular weight and viscosity of the rapeseed oil (which is conducive to the penetration of the softener into the inside of the leather), but also can be used as an intermediate to undergo epoxidation reaction again.

[0016] The present application finds that the ratio of methanol and rapeseed oil is critical in the alcoholysis reaction, if the alcohol oil ratio is too low, the alcoholysis degree is low, and the modification purpose cannot be achieved, if the alcohol oil ratio is too high, the separation of glycerol will be affected, and the conversion rate cannot be improved, finally the present application finds that the alcohol oil ratio in the range of 3-4:1 is the best.

[0017] In step 3), the carbon-carbon double bond in the rapeseed oil is oxidized by hydrogen peroxide to form an epoxy structure, and the epoxidation reaction can reduce the iodine value of the rapeseed oil and improve the oxidation stability of the rapeseed oil.

[0018] In step 6), the epoxidized modified rapeseed oil has an epoxy structure, and the addition of sodium bisulfite aqueous solution sulfites the epoxy structure to introduce a hydrophilic sodium sulfonate group (-SO3Na) on the carbon chain, which can significantly enhance the water solubility and has good self-emulsifying performance. Therefore, the modified rapeseed oil obtained finally has better permeability and emulsion stability than the sulfated softening agent.

[0019] The present application finds that the amount of sodium bisulfite is critical in the sulfiting reaction, if the amount of sodium bisulfite is too low, the emulsification of the product is poor, and the emulsion stability is not good, if the amount of sodium bisulfite is too high, there is too much residual sulfite, which will directly affect the softening effect when the content exceeds a certain value. Finally, the present application finds that the amount of sodium bisulfite is 20-30% of the mass of the epoxidized modified rapeseed oil, which is the best.

[0020] As preferred, in step 1), the rapeseed oil is subjected to pre-drying and deacidification treatment.

[0021] As preferred, in step 1), the alcoholysis reaction time is 2-3h.

[0022] As preferred, in step 3), the catalyst is a strong acid cation exchange resin.

[0023] As preferred, in step 3), the amount of catalyst is 4.5-5.0% of the mass of the rapeseed oil.

[0024] As preferred, in step 3), the reaction time is 20-40min.

[0025] As preferred, in step 4), the base is KOH solution.

[0026] As preferred, in step 6), the reaction time is 15-25min.

[0027] As preferred, in step 7), the stirring time is 2-3h.

[0028] Compared with the prior art, the present application has the following advantages:

[0029] (1) The present application takes rapeseed oil as the main raw material of the leather softener, first carries out alcoholysis reaction with methanol to introduce excess hydroxyl groups, which can not only reduce the molecular weight and viscosity of rapeseed oil (which is conducive to the penetration of the softener into the inside of the leather), but also can make it as an intermediate to undergo other reactions; on this basis, continue to use hydrogen peroxide to make the carbon-carbon double bond in the rapeseed oil be oxidized to form an epoxy structure, which can improve the oxidation stability of the rapeseed oil; further, sulfite modification is carried out, and sulfonic acid groups are introduced into the molecule, which can significantly enhance the water solubility and has good self-emulsifying performance. Therefore, the final obtained leather softener has excellent penetration and emulsion stability.

[0030] (2) The leather softener prepared by the method of the present application can significantly improve the softness of the leather cultural relics, and the leather softener is environmentally friendly and harmless to the leather cultural relics. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The color difference value of the aged leather and the softened leather.

[0032] Figure 2 The tensile strength and elongation at break of the aged leather before and after softening. DETAILED DESCRIPTION

[0033] The present application will be further described below in combination with examples.

[0034] Example 1

[0035] Step 1): A 250 mL three-necked flask was slowly added with methanol and rapeseed oil (previously dried and deacidified) in a mass ratio of 3:1, and stirred for 20 min. 0.5 wt% sodium methoxide of rapeseed oil was added to the three-necked flask. The temperature was raised to 60℃, and the reaction was carried out for 3 h. After the reaction was completed, the product was filtered to obtain alcoholized rapeseed oil.

[0036] Step 2): A 250 mL three-necked flask was added with alcoholized rapeseed oil, 9% acetic acid and 4.5% strong acid cation exchange resin (cationic resin (732)) of the mass of alcoholized rapeseed oil, and the temperature was raised to 50℃, and the reaction was carried out for 30 min. Hydrogen peroxide (30%) of 40% alcoholized rapeseed oil was slowly added through a dropping funnel, and the addition was completed within 30 min. 4.0% KOH solution was added to adjust the pH to neutral, and after the reaction was completed, the product was separated into layers, washed with water for several times, and the water layer was removed to obtain epoxidized modified rapeseed oil.

[0037] Step 3): The epoxidized modified rapeseed oil was moved into a 250 mL three-necked flask with stirring and reflux device, and sodium bisulfite aqueous solution was slowly added at 55°C for 20 min, the amount of sodium bisulfite was 20% of the mass of the epoxidized modified rapeseed oil, then 2% of sodium dodecyl sulfonate was added, the temperature was raised to 80°C, and stirring was performed for 2.5 h to obtain the modified rapeseed oil leather softener.

[0038] Example 2

[0039] Step 1): Methanol and rapeseed oil (previously dried and deacidified) in a mass ratio of 4:1 were slowly added to a 250 mL three-necked flask, and stirring was performed for 20 min. Sodium methoxide was added to the three-necked flask at 0.5 wt% of the rapeseed oil. The temperature was raised to 60°C, and constant temperature reaction was performed for 3 h. After the reaction was completed, the product was filtered to obtain alcoholysis rapeseed oil.

[0040] Step 2): Alcoholysis rapeseed oil, 9% acetic acid of the mass of the alcoholysis rapeseed oil, and 4.5% strong acid cation exchange resin (cationic resin (732)) were added to a 250 mL three-necked flask, and the temperature was raised to 50°C for reaction for 30 min. Hydrogen peroxide (30%) at 40% of the alcoholysis rapeseed oil was slowly added dropwise through a dropping funnel, and the addition was completed within 30 min. 4.0% KOH solution was added to adjust the pH to neutral, and after the reaction was completed, the product was separated into layers, washed with water several times, and the water layer was removed to obtain epoxidized modified rapeseed oil.

[0041] Step 3): The epoxidized modified rapeseed oil was moved into a 250 mL three-necked flask with stirring and reflux device, and sodium bisulfite aqueous solution was slowly added at 55°C for 20 min, the amount of sodium bisulfite was 20% of the mass of the epoxidized modified rapeseed oil, then 2% of sodium dodecyl sulfonate was added, the temperature was raised to 80°C, and stirring was performed for 2.5 h to obtain the modified rapeseed oil leather softener.

[0042] Comparative Example 1 (with reference to Example 1, the difference is that in step 1), the ratio of alcohol to oil is 2:1)

[0043] Step 1): Methanol and rapeseed oil (previously dried and deacidified) in a mass ratio of 2:1 were slowly added to a 250 mL three-necked flask, and stirring was performed for 20 min. Sodium methoxide was added to the three-necked flask at 0.5 wt% of the rapeseed oil. The temperature was raised to 60°C, and constant temperature reaction was performed for 3 h. After the reaction was completed, the product was filtered to obtain alcoholysis rapeseed oil.

[0044] Step 2): A 250 mL three-necked flask was charged with alcoholysis rapeseed oil, 9% of acetic acid and 4.5% of strong acid cation exchange resin (cation resin (732)) by mass of alcoholysis rapeseed oil, and warmed to 50°C and reacted for 30 min. Hydrogen peroxide (30%) was slowly added dropwise through a dropping funnel at a rate of 40% of alcoholysis rapeseed oil over 30 min. A 4.0% KOH solution was added to adjust the pH to neutral, and the reaction was completed. The product was separated into layers, washed with water several times, and the water layer was removed to obtain the epoxidized modified rapeseed oil.

[0045] Step 3): The epoxidized modified rapeseed oil was transferred into a 250 mL three-necked flask with stirring and refluxing device, and sodium bisulfite aqueous solution was slowly added at 55°C and reacted for 20 min. The amount of sodium bisulfite was 20% of the mass of the epoxidized modified rapeseed oil. Then 2% of sodium dodecyl sulfonate was added, and the temperature was raised to 80°C and stirred for 2.5 h to obtain the modified rapeseed oil leather softener.

[0046] Comparative Example 2 (with reference to Example 1, the difference is that in step 1) the ratio of methanol to rapeseed oil is 5:1)

[0047] Step 1): A 250 mL three-necked flask was charged with methanol and rapeseed oil (previously dried and deacidified) at a mass ratio of 5:1, and stirred for 20 min. Sodium methoxide was added to the three-necked flask at 0.5 wt% of rapeseed oil. The temperature was raised to 60°C and reacted for 3 h. After the reaction was completed, the product was filtered to obtain alcoholysis rapeseed oil.

[0048] Step 2): A 250 mL three-necked flask was charged with alcoholysis rapeseed oil, 9% of acetic acid and 4.5% of strong acid cation exchange resin (cation resin (732)) by mass of alcoholysis rapeseed oil, and warmed to 50°C and reacted for 30 min. Hydrogen peroxide (30%) was slowly added dropwise through a dropping funnel at a rate of 40% of alcoholysis rapeseed oil over 30 min. A 4.0% KOH solution was added to adjust the pH to neutral, and the reaction was completed. The product was separated into layers, washed with water several times, and the water layer was removed to obtain the epoxidized modified rapeseed oil.

[0049] Step 3): The epoxidized modified rapeseed oil was transferred into a 250 mL three-necked flask with stirring and refluxing device, and sodium bisulfite aqueous solution was slowly added at 55°C and reacted for 20 min. The amount of sodium bisulfite was 20% of the mass of the epoxidized modified rapeseed oil. Then 2% of sodium dodecyl sulfonate was added, and the temperature was raised to 80°C and stirred for 2.5 h to obtain the modified rapeseed oil leather softener.

[0050] Comparative Example 3 (with reference to Example 1, the difference is that in step 3) the amount of sodium bisulfite is 15% of the mass of the epoxidized modified rapeseed oil)

[0051] Step 1): A 250 mL three-necked flask was charged with methanol and rapeseed oil (previously dried and deacidified) in a mass ratio of 3:1 slowly, and stirred for 20 min. Sodium methoxide (0.5 wt% of rapeseed oil) was added to the three-necked flask. The temperature was raised to 60°C, and the reaction was kept at this temperature for 3 h. After the reaction was completed, the product was filtered to obtain alcoholysis rapeseed oil.

[0052] Step 2): A 250 mL three-necked flask was charged with alcoholysis rapeseed oil, acetic acid (9% of the mass of alcoholysis rapeseed oil), and strong acid cation exchange resin (cation resin (732)) (4.5%), and the temperature was raised to 50°C, and the reaction was kept at this temperature for 30 min. Hydrogen peroxide (30%) (40% of alcoholysis rapeseed oil) was slowly added dropwise through a dropping funnel, and the addition was completed within 30 min. A 4.0% KOH solution was added to adjust the pH to neutral, and after the reaction was completed, the product was separated into layers, washed with water several times, and the water layer was removed to obtain epoxidized modified rapeseed oil.

[0053] Step 3): The epoxidized modified rapeseed oil was transferred to a 250 mL three-necked flask equipped with a stirring and reflux device, and sodium bisulfite aqueous solution was slowly added at 55°C for 20 min. The amount of sodium bisulfite was 15% of the mass of epoxidized modified rapeseed oil, and then 2% of sodium dodecyl sulfonate was added. The temperature was raised to 80°C, and the stirring was kept for 2.5 h to obtain modified rapeseed oil leather softener.

[0054] Comparative Example 4 (with reference to Example 1, the difference is that in step 3), the amount of sodium bisulfite is 35% of the mass of epoxidized modified rapeseed oil)

[0055] Step 1): A 250 mL three-necked flask was charged with methanol and rapeseed oil (previously dried and deacidified) in a mass ratio of 3:1 slowly, and stirred for 20 min. Sodium methoxide (0.5 wt% of rapeseed oil) was added to the three-necked flask. The temperature was raised to 60°C, and the reaction was kept at this temperature for 3 h. After the reaction was completed, the product was filtered to obtain alcoholysis rapeseed oil.

[0056] Step 2): A 250 mL three-necked flask was charged with alcoholysis rapeseed oil, acetic acid (9% of the mass of alcoholysis rapeseed oil), and strong acid cation exchange resin (cation resin (732)) (4.5%), and the temperature was raised to 50°C, and the reaction was kept at this temperature for 30 min. Hydrogen peroxide (30%) (40% of alcoholysis rapeseed oil) was slowly added dropwise through a dropping funnel, and the addition was completed within 30 min. A 4.0% KOH solution was added to adjust the pH to neutral, and after the reaction was completed, the product was separated into layers, washed with water several times, and the water layer was removed to obtain epoxidized modified rapeseed oil.

[0057] Step 3): The epoxidized modified rapeseed oil was moved into a 250 mL three-necked flask with stirring and reflux device, and sodium bisulfite aqueous solution was slowly added at 55°C for 20 min, the amount of sodium bisulfite was 35% of the mass of the epoxidized modified rapeseed oil, then 2% of sodium dodecyl sulfonate was added, the temperature was raised to 80°C, and stirring was carried out for 2.5 h to obtain the modified rapeseed oil leather softener.

[0058] Application Example 1:

[0059] (1) Preparation of aged leather samples: Cut 10 cm x 10 cm samples from the same piece of vegetable-tanned cowhide, ensuring that the properties are similar by taking samples from similar parts of the back ridge on both sides. Place the samples in a 150°C forced air drying oven for 8 h.

[0060] (2) Cut approximately 3 cm x 3 cm samples from the aged leather samples, then weigh, measure the size, and softness of the aged leather samples, and record the data.

[0061] (3) Softening of the aged samples: Spray a small amount of 2A solution (prepared by mixing anhydrous ethanol and deionized water at a ratio of 1:1) onto the surface of the aged leather samples, let stand for 20 min, and then use a soft brush to dip and apply the softener to the surface of the leather in multiple small amounts until the surface is covered with a thin layer of softener. After the softener has fully penetrated, wipe off the residual softener on the surface and weigh. Repeat the softening operation 5 times to achieve saturation, and then measure the mass, size, and softness of the samples.

[0062] Test the properties of the above-softened leather samples:

[0063] (1) Emulsion stability test:

[0064] ① 1:9 dilution stability: Take 90 mL of hot distilled water at about 55°C in a 100 mL graduated cylinder with a stopper, and add 10 mL of the sample. Tighten the stopper, flip up and down for 1 min, shake well, and then let stand at 28°C for 24 h.

[0065] ② Stability to 1 mol / L ammonia solution: Take 80 mL of hot distilled water at about 55°C in a 100 mL graduated cylinder with a stopper, add 10 mL of the sample, shake well, then add 10 mL of ammonia solution, tighten the stopper, flip up and down for 1 min, shake well, and then let stand at 25-30°C for 24 h.

[0066] ③ Stability to 1 mol / L hydrochloric acid solution: Take 80 mL of hot distilled water at about 55°C in a 100 mL graduated cylinder with a stopper, add 10 mL of the sample, shake well, then add 10 mL of HCl solution, tighten the stopper, flip up and down for 1 min, shake well, and then let stand at 28°C for 24 h.

[0067] (2) Color difference test: Take the unaged leather as the standard sample, use the color difference meter to test the color difference of the same sample after aging, select 3 different points and take the average value.

[0068] (3) Softness: Use the softness tester to test the softness of the same sample on 3 different points and take the average value.

[0069] (4) Tensile test: Use the electronic universal material testing machine to test the tensile stress and elongation at break of the leather sample according to the national standard QB / T 2710-2018.

[0070] Performance comparison

[0071] Table 1 Performance of different softening agents

[0072]

[0073] From the emulsion stability, acid resistance, alkali resistance, color and storage stability, the performance of softening agent 1# is the most ideal. The amount of sodium bisulfite directly affects the emulsification of the softening agent. If the amount is small, the emulsification is poor and the emulsion stability is not good; if the amount is large, there is more residual sulfite in the softening agent, which affects the emulsion stability of the softening agent.

[0074] From Figure 1 It can be seen that after the aging leather is treated with the softening agent, the surface of the leather restores a certain gloss and the color of the leather sample is more full, so there is a certain color difference compared with before softening. Among them, the color difference of softening agent 1# changes the most compared with before softening, which indicates that the gloss of the aging leather after softening is strong. The molar ratio of alcohol to oil in softening agent 1# is 3:1, the alcoholysis reaction degree is the largest, the molecular weight and viscosity of rapeseed oil are reduced, the softening agent can easily penetrate into the inside of the leather and combine with the fibers, and the softening effect is good.

[0075] Table 2 Change of softness of aging leather after softening

[0076]

[0077] As shown in Table 2, Figure 2 the softness and mechanical properties of the aging leather sample are improved after softening, the softening agent emulsion penetrates into the collagen fibers, and part of the softening agent fills between the collagen fibers. The sulfited softening agent has better acid resistance and electrolyte resistance, which makes the softened leather more soft and full. When the amount of sodium bisulfite is 20%, the sulfiting degree is high, which improves the uniformity of the softening agent in the leather, improves the softening effect, and improves the mechanical properties of the leather. It shows that the softening agent in the application has good permeability and filling property for leather cultural relics. Rapeseed oil is an eco-friendly material, easy to degrade, and harmless to cultural relics.

[0078] The raw materials and equipment used in the present application are conventional raw materials and equipment in the art unless otherwise specified; the methods used in the present application are conventional methods in the art unless otherwise specified.

[0079] The above is only the preferred embodiment of the present application, and does not limit the present application in any way. Any simple modification, change and equivalent transformation of the above embodiment based on the technical essence of the present application still falls within the protection scope of the technical solution of the present application.

Claims

1. A method for preparing a modified rapeseed oil leather softener, characterized by The method comprises the following steps: 1) mixing rapeseed oil and methanol uniformly, adding catalyst sodium methoxide, stirring and refluxing at 60-65℃, and performing alcoholysis reaction in inert atmosphere; the mass ratio of methanol to rapeseed oil is 3-4:1; 2) after the reaction is completed, recovering excessive methanol by distillation under reduced pressure, and separating the upper oil layer to obtain alcoholized rapeseed oil; 3) mixing alcoholized rapeseed oil, acetic acid and catalyst, stirring and heating to 50-56℃, and adding hydrogen peroxide to the system for reaction; the amount of acetic acid is 7-11% of the mass of alcoholized rapeseed oil; the concentration of hydrogen peroxide is 25-35wt%, and the amount is 40-45% of the mass of alcoholized rapeseed oil; 4) adding alkali to the reaction system for neutralization, and removing the water layer after separation; 5) washing the product obtained in step 4) with water, removing the water layer after standing to obtain epoxidized modified rapeseed oil; 6) heating epoxidized modified rapeseed oil to 50-60℃, and adding sodium bisulfite aqueous solution dropwise for reaction; the amount of sodium bisulfite is 20-30% of the mass of epoxidized modified rapeseed oil; 7) adding 1-3wt% of sodium dodecyl sulfonate to the system of step 6), heating to 80-90℃ and stirring uniformly to obtain modified rapeseed oil leather softener.

2. The method of claim 1, wherein: In step 1), the rapeseed oil is subjected to pre-drying and deacidification treatment.

3. The method of claim 1, wherein: In step 1), the time of alcoholysis reaction is 2-3h.

4. The method of claim 1, wherein: In step 3), the catalyst is strong acid cation exchange resin.

5. The method of claim 4, wherein: In step 3), the amount of catalyst is 4.5-5.0% of the mass of rapeseed oil.

6. The method of claim 1, wherein: In step 3), the reaction time is 20-40min.

7. The method of claim 1, wherein: In step 4), the alkali is KOH solution.

8. The method of claim 1, wherein: In step 6), the reaction time is 15-25min.

9. The method of claim 1, wherein: In step 7), the stirring time is 2-3h.

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