Silicone oil modified leather fatliquor and preparation method thereof

Abstract

The invention belongs to the field of leather auxiliaries, and particularly relates to a silicone oil modified leather fatting agent and a preparation method thereof. The preparation method comprises the following steps: dehydrating double-end polyether silicone oil, and reacting with an acidic reactant to obtain functional silicone oil containing double bonds and carboxyl at double ends; dropwise adding into a sulfite aqueous solution for reaction to obtain a first product; dehydrating the other part of double-end polyether silicone oil, reacting with phosphorus pentoxide, adding ammonia water mixed liquor, and stirring to obtain a second product; mixing and stirring the first product, the second product, an emulsifier, white oil and water to obtain a finished product. The method is simple and environment-friendly in process, free of toxic solvents and high-price catalysts, good in product permeability, firm in combination with leather fibers, capable of remarkably improving the softness and yellowing resistance of leather, suitable for industrial production and wide in application prospect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of leather auxiliaries, and particularly relates to a silicone oil modified leather fatliquor and a preparation method thereof. BACKGROUND

[0002] Silicone oil is the abbreviation of organic polysiloxane, which is widely used in various industries. In the leather industry, silicone oil is mainly used in finishing and fatliquoring processes. In the fatliquoring process, it is mainly used as a fatliquor, which can give the leather good softness and certain waterproof performance. Fatliquoring is an important process in leather production. Through the interaction between fatliquor and leather fibers, the leather can be given good hand feeling, restoring the softness and elasticity of the leather itself. In addition, the toughness, tensile strength, elongation rate and other physical and chemical strength of the fatliquored leather are also improved. Silicone as a fatliquor mainly utilizes its good softness and waterproof ability. Currently, silicone fatliquor is mostly used by compounding silicone oil with external emulsifiers or by grafting modification of silicone oil to make it have emulsifying ability. The former has poor water solubility and weak penetration ability, and is only suitable for surface fatliquoring. The latter needs a complicated modification process.

[0003] Patent application with publication number CN104479551A discloses a waterproof leather fatliquor prepared from dimethyl polysiloxane, hydroxy polysiloxane, amino polysiloxane, cottonseed oil, turpentine oil, paraffin, ethanol, chromium chloride and water. The fatliquored leather has significantly improved waterproof performance and aging resistance. However, the silicone oil and other oils used in the application do not have emulsifying properties, so the penetration is poor, the fatliquoring effect is limited, and the waste product contains chromium ions, increasing the cost of wastewater treatment.

[0004] Patent application with publication number CN104829842A discloses a functional polysiloxane with double bonds and epoxy groups at both ends, which is synthesized from allyl glycidyl ether and end-hydrogen-containing polysiloxane, and then reacted with a first-generation polyamide-amine to obtain a silicon-containing dendrimer-linear fatliquor. The product can give the leather good softness and fullness. The synthesis process in this production scheme is complex, a large amount of toxic solvent is used, and the cost of catalyst is high, which is not suitable for industrial production.

[0005] Patent with publication number CN120666126A discloses a polyether modified silicone oil prepared from end-hydrogen-containing silicone oil and allyl ether, and then compounded with an emulsifier to obtain a product. The treated leather has significantly improved tensile strength, tear strength and hydrophobic effect, while maintaining good softness. This scheme lacks polar functional groups, and the active substances cannot be fully fixed in the leather.

[0006] Therefore, the present application is proposed based on the above. SUMMARY

[0007] To address the problems existing in the prior art, the present invention provides a method for preparing a silicone oil-modified leather fatliquoring agent, the preparation method comprising the following steps: (1) The double-ended polyether silicone oil is dried by dehydration, and then an acidic reactant is added and heated to react, so as to obtain a functional silicone oil with double bonds and carboxyl groups at both ends; (2) The functional silicone oil containing double bonds and carboxyl groups at both ends is added dropwise to the aqueous solution of sulfite. After the addition is complete, the mixture is heated to react and the first product is obtained. (3) The double-ended polyether silicone oil was dried by dehydration, then phosphorus pentoxide was added and heated to react, and then a mixture of ammonia water was added and stirred to obtain the second product; (4) Mix and stir the first product, the second product, the emulsifier, the white oil and water to obtain the silicone oil modified leather fatliquoring agent.

[0008] Preferably, in step (1): The weight ratio of the double-ended polyether silicone oil to the acidic reactant is 400:15-30; And / or, the acidic reactant is one or a combination of two or more of maleic anhydride, maleic acid, and p-toluenesulfonic acid.

[0009] Preferably, in step (1): The method for dehydration and drying is as follows: vacuuming and heating to 80-90℃ and maintaining for 1-2 hours; And / or, the heating reaction temperature is 85-95℃, and the heating reaction time is 3-4h.

[0010] Preferably, in step (2): the sulfite aqueous solution is prepared by mixing a sulfite compound with water; And / or, the sulfite compound is sodium sulfite or sodium metabisulfite; And / or, the weight ratio of the sulfite compound to the water is 19-26:431-445.

[0011] Preferably, in step (2), the temperature of the heating reaction is 70-80℃ and the heating reaction time is 4-5h.

[0012] Preferably, in step (3): The weight ratio of the double-ended polyether silicone oil to the phosphorus pentoxide is 400:50-60; And / or, the ammonia mixture is made by mixing ammonia and water, wherein the concentration of the ammonia is 20-30% and the weight ratio of ammonia to water is 60-70:390-400.

[0013] Preferably, in step (3): The heating reaction is carried out at a temperature of 70-80℃ for 3-4 hours. And / or, continue stirring for 1-2 hours.

[0014] Preferably, in step (4): The emulsifier is one or a combination of two or more of the following: isotretinoin polyoxyethylene ether-3, isotretinoin polyoxyethylene ether-5, isotretinoin polyoxyethylene ether-7, and isotretinoin polyoxyethylene ether-10. And / or, the weight ratio of the first product, the second product, the emulsifier, the white oil and water is 20-30:10-20:5-7:10-15:10-15.

[0015] Based on the same technical concept, the present invention aims to provide a silicone oil-modified leather fatliquoring agent obtained by the above preparation method.

[0016] The beneficial effects of this invention are as follows: 1. Excellent penetration and deep and uniform fatliquoring effect: By functionalizing double-bond carboxyl groups and modifying double-ended polyether silicone oil with sulfonation and phosphorylation, polar functional groups such as carboxyl groups, sulfonic acid groups, and phosphoric acid groups are introduced, which greatly enhances the interaction ability with leather fibers, solves the problems of poor hydrophilicity and weak penetration of traditional silicone oil fatliquoring agents, achieves deep fatliquoring of leather, and avoids surface oil floating.

[0017] 2. The process is simple and environmentally friendly, and suitable for industrial production: It does not require the use of toxic solvents and expensive catalysts. The modification steps are streamlined, the reaction conditions are mild (temperature 70-95℃, time 1-5h), and the operation is easy to control. The product contains no harmful components such as chromium ions, which reduces wastewater treatment costs and meets environmental protection production requirements.

[0018] 3. Comprehensive improvement in leather performance: Leather treated with this fatliquoring agent has significantly better softness than similar products on the market (softness of Example 1 is 7.12mm, softness of Example 2 is 7.21mm, and softness of commercially available products is 6.74mm); it also has outstanding resistance to yellowing, with resistance to yellowing under sunlight reaching level 3-4, resistance to yellowing under ultraviolet light reaching level 4 or above, and resistance to yellowing under heat reaching level 4, effectively extending the service life of the leather.

[0019] 4. Synergistic and stable composition: The first product (sulfonated functional silicone oil) and the second product (phosphorylated polyether silicone oil) are combined with a specific emulsifier, resulting in uniform dispersion and strong stability of the system. The active ingredients can firmly adhere to the leather fibers and are not prone to failure with long-term use. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] Example 1 This embodiment provides a method for preparing a silicone oil-modified leather fatliquoring agent, the preparation method comprising the following steps: (1) Raw material preparation: Accurately weigh 400g of double-ended polyether silicone oil (model DOWSIL) TM BY 16-201), 19.8g maleic anhydride, 25.5g sodium sulfite, 445g purified water, 56.8g phosphorus pentoxide, 65.9g 20% ​​ammonia solution, 392g purified water, 5g isomeric tridecyl alcohol polyoxyethylene ether-3, 10g No. 26 white oil, 10g purified water; check that the reaction flask, stirring device, temperature control equipment (accuracy ±1℃), and dropping funnel are clean and dry, ensuring no impurities remain. Accurate ingredient mixing ensures the reaction ratio meets design requirements; clean and dry equipment avoids impurities and residual moisture interfering with the reaction process; calibrated temperature control equipment ensures stable reaction temperature.

[0022] (2) Preparation of functional silicone oil: (2-1) Add 400g of weighed double-ended polyether silicone oil to a dry reaction flask, install the stirring and vacuum devices, start the vacuum pump to create a vacuum, and simultaneously heat the oil bath to 85℃, maintaining this state for 1 hour to remove moisture and dry the product. After completion, turn off the vacuum pump and oil bath, and allow the product to cool naturally to 60℃. Vacuuming and heating to remove moisture can completely remove free water from the double-ended polyether silicone oil, preventing moisture from affecting the efficiency of the subsequent esterification reaction with acidic reactants and the purity of the product.

[0023] (2-2) Slowly add 19.8 g of maleic anhydride to the dehydrated double-ended polyether silicone oil and stir continuously. After the addition is complete, start the oil bath to raise the system temperature to 90°C and maintain this temperature for 3 hours. Record the system temperature every 30 minutes during this period. After the reaction is completed, turn off the oil bath to obtain a functional silicone oil with double bonds and carboxyl groups at both ends, which can be used for later use. Slow addition avoids violent local reactions that may cause a sudden rise in temperature. Maleic anhydride, as an acidic reactant, undergoes an esterification reaction with the terminal hydroxyl groups of the double-ended polyether silicone oil, introducing double bonds and carboxyl functional groups, providing reaction sites for subsequent sulfonation modification. The reaction temperature of 90°C and the reaction time of 3 hours ensure that the esterification reaction is fully carried out.

[0024] (3) Preparation of the first product: (3-1) Take another clean reaction flask, add 445g of pure water, start stirring (250r / min), slowly add 25.5g of sodium sulfite, stir for 15min until the sodium sulfite is completely dissolved, and obtain an aqueous solution of sulfite.

[0025] (3-2) The functional silicone oil with double bonds and carboxyl groups prepared above is slowly added dropwise to the sulfite aqueous solution through a dropping funnel. During the addition, the system temperature is controlled at 65℃ (error ±2℃) to prevent the double bond side reaction caused by excessive temperature.

[0026] (3-3) After the addition is complete, start the oil bath and heat it to 75°C. Maintain this temperature and continue stirring for 4 hours. After the reaction is complete, turn off the oil bath and let it cool naturally to room temperature to obtain the first product. Seal it for later use.

[0027] (4) Preparation of the second product: (4-1) Take a clean and dry reaction flask and add 400g of double-ended polyether silicone oil (DOWSIL). TM (BY 16-201) Repeat step (2-1) for water removal: vacuum (-0.09MPa), heat the oil bath to 85℃, keep it at that temperature for 1 hour, and cool it to 60℃ to ensure thorough water removal.

[0028] (4-2) Add 56.8g of phosphorus pentoxide to the dehydrated double-ended polyether silicone oil in batches (add in 5 batches, 10min apart, each batch containing 11.36g), stirring continuously during the process, and controlling the system temperature to not exceed 70℃ during the addition. Batch addition and temperature control can avoid the violent exothermic reaction between phosphorus pentoxide and silicone oil, which could lead to temperature runaway.

[0029] (4-3) After the addition of materials is complete, start the oil bath and heat it to 75°C. Maintain this temperature and stir the reaction for 3 hours. During this period, observe the state of the system to ensure that there is no clumping. Around 75°C is the optimal temperature for phosphorylation reaction. The 3-hour reaction time ensures that the reaction is complete. Stirring evenly avoids product clumping and improves product dispersibility.

[0030] (4-4) After the reaction is complete, turn off the oil bath and cool the system temperature to 40℃ (error ±2℃). Slowly add a mixed solution consisting of 65.9g of 20% ammonia water and 392g of pure water dropwise into the system through a dropping funnel while continuously stirring. Dropwise addition at 40℃ can avoid the volatilization of ammonia water, and slow addition ensures stable adjustment of the pH value of the system, neutralizes some acidic groups, and improves the stability of the product.

[0031] (4-5) After the addition is complete, continue stirring for 1 hour to ensure the system is fully neutralized and homogeneous, obtaining the second product. Seal and store for later use. Extending the stirring time ensures complete neutralization and avoids local acid-base imbalances that could affect product performance. The ammonium salt form further enhances the product's hydrophilicity.

[0032] (5) Finished product preparation: Under stirring conditions at 60°C, 20g of the first product, 20g of the second product, 5g of isomeric tridecyl alcohol polyoxyethylene ether-3, 10g of No. 26 white oil and 10g of water were added sequentially to the reaction flask. The mixture was kept warm and stirred for 1 hour. After natural cooling, the silicone oil modified leather fatliquoring agent was obtained.

[0033] Example 2 This embodiment provides a method for preparing a silicone oil-modified leather fatliquoring agent, which is basically the same as the operation in Example 1, with only some parameters being adjusted adaptively. The preparation method is briefly described as follows: (1) Add 400g of double-ended polyether silicone oil (DOWSIL) TM Add BY 16-201) to the reaction flask, heat to 85℃ and keep under vacuum for 1 hour, then add 19.8 g maleic anhydride, heat to 90℃ and react for 3 hours to obtain a functional silicone oil with double bonds and carboxyl groups at both ends.

[0034] (2) Dissolve 19.3g of sodium metabisulfite in 431g of pure water, then add 20.2g of 30% sodium hydroxide solution to prepare a solution. Then add the functional silicone oil with double bonds and carboxyl groups at both ends to the solution. During the transfer, control the system temperature at 65℃. After the transfer is completed, raise the temperature to 75℃ and react for 4h to obtain the first product.

[0035] (3) Add 400g of double-ended polyether silicone oil (DOWSIL) TM Add (BY 16-201) to the reaction flask, heat to 85℃, keep warm and vacuum for 1 hour to remove water and dry, then slowly add 56.8g of phosphorus pentoxide in batches. After the addition is complete, heat to 75℃ and react for 3 hours. After the reaction is complete, cool down to 40℃ and add a mixed solution consisting of 65.9g of 20% ammonia water and 392g of pure water dropwise to the system. After the dropwise addition is complete, continue stirring for 1 hour to obtain the second product.

[0036] (4) Under stirring conditions at 60°C, 30g of the first product, 10g of the second product, 5g of isomeric tridecyl alcohol polyoxyethylene ether-3, 10g of No. 26 white oil and 10g of water were added to the reaction flask in sequence. The mixture was kept warm and stirred for 1 hour. After natural cooling, the silicone oil modified leather fatliquoring agent was obtained.

[0037] Test Example To investigate the fatliquoring effect of the obtained silicone oil-modified leather fatliquoring agent, the present invention was conducted according to the following process (as shown in Table 1). A uniformly shaved piece of wet blue cowhide was taken, and the amount of each material used in the process was calculated as a percentage of the mass of the wet blue cowhide.

[0038] Table 1

[0039] The results of the tests on Example 1, Example 2 and the commercially available product Davelle-AF (resistance to sun lamp yellowing test GT-7035-EUA; resistance to ultraviolet yellowing test GT-7035-UB; resistance to heat yellowing GT-705-R; softness test GB / T 39371-2020) are shown in Table 2.

[0040] Table 2

[0041] As shown in Table 2, the silicone oil-modified leather fatliquoring agents obtained in Examples 1 and 2 are superior to commercially available similar products in all aspects.

[0042] Note: Based on the characteristics of the test, Example 1 and Daval-AF a For simultaneous detection of two groups, Example 2 and Daval-AF b These are two groups being tested simultaneously. Groups a and b differ only in their numbering; they are essentially the same.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a silicone oil-modified leather fatliquoring agent, characterized in that, The preparation method includes the following steps: (1) The double-ended polyether silicone oil is dried by dehydration, and then an acidic reactant is added and heated to react, so as to obtain a functional silicone oil with double bonds and carboxyl groups at both ends; (2) The functional silicone oil containing double bonds and carboxyl groups at both ends is added dropwise to the aqueous solution of sulfite. After the addition is complete, the mixture is heated to react and the first product is obtained. (3) The double-ended polyether silicone oil was dried by dehydration, then phosphorus pentoxide was added and heated to react, and then a mixture of ammonia water was added and stirred to obtain the second product; (4) Mix and stir the first product, the second product, the emulsifier, the white oil and water to obtain the silicone oil modified leather fatliquoring agent.

2. The preparation method of the silicone oil-modified leather fatliquoring agent according to claim 1, characterized in that, In step (1): The weight ratio of the double-ended polyether silicone oil to the acidic reactant is 400:15-30; And / or, the acidic reactant is one or a combination of two or more of maleic anhydride, maleic acid, and p-toluenesulfonic acid.

3. The preparation method of the silicone oil-modified leather fatliquoring agent according to claim 1, characterized in that, In step (1): The method for dehydration and drying is as follows: vacuuming and heating to 80-90℃ and maintaining for 1-2 hours; And / or, the heating reaction temperature is 85-95℃, and the heating reaction time is 3-4h.

4. The preparation method of the silicone oil-modified leather fatliquoring agent according to claim 1, characterized in that, In step (2): the sulfite aqueous solution is prepared by mixing a sulfite compound with water; And / or, the sulfite compound is sodium sulfite or sodium metabisulfite; And / or, the weight ratio of the sulfite compound to the water is 19-26:431-445.

5. The preparation method of the silicone oil-modified leather fatliquoring agent according to claim 1, characterized in that, In step (2), the temperature of the heating reaction is 70-80℃ and the heating reaction time is 4-5h.

6. The preparation method of the silicone oil-modified leather fatliquoring agent according to claim 1, characterized in that, In step (3): The weight ratio of the double-ended polyether silicone oil to the phosphorus pentoxide is 400:50-60; And / or, the ammonia mixture is made by mixing ammonia and water, wherein the concentration of the ammonia is 20-30% and the weight ratio of ammonia to water is 60-70:390-400.

7. The preparation method of the silicone oil-modified leather fatliquoring agent according to claim 1, characterized in that, In step (3): The heating reaction is carried out at a temperature of 70-80℃ for 3-4 hours. And / or, continue stirring for 1-2 hours.

8. The preparation method of the silicone oil-modified leather fatliquoring agent according to claim 1, characterized in that, In step (4): The emulsifier is one or a combination of two or more of the following: isotretinoin polyoxyethylene ether-3, isotretinoin polyoxyethylene ether-5, isotretinoin polyoxyethylene ether-7, and isotretinoin polyoxyethylene ether-10. And / or, the weight ratio of the first product, the second product, the emulsifier, the white oil and water is 20-30:10-20:5-7:10-15:10-15.

9. The silicone oil-modified leather fatliquoring agent obtained by the preparation method according to any one of claims 1-8.

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