Modified polyester base for leather fatliquors and their use, and methods of preparation and use

Abstract

The application discloses a kind of leather fatliquor and its using modified polyester base material and preparation method and application.C21 dibasic acid esterification modified polyester base material for leather fatliquor, by C21 dibasic acid and the esterification reaction product of hydroxyl-containing compound successively by sulphation reaction, strong base neutralization reaction is prepared, the polymer main chain of the C21 dibasic acid esterification modified polyester base material contains the carboxylic ester bond connection unit formed by C21 dibasic acid and hydroxyl-containing compound reaction;The weight average molecular weight of the hydroxyl-containing compound is 500-3000, is at least one selected from polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene oxide-polypropylene oxide block copolymer and polyethylene oxide-polypropylene oxide-polyethylene oxide tri-block copolymer, and the C21 dibasic acid and hydroxyl-containing compound are carried out esterification reaction in the presence of catalyst.The application also discloses a composite leather fatliquor comprising the polyester base material, white oil, antioxidant and preservative.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and leather chemical technology, specifically relating to a C21 diester-modified polyester base material for leather fatliquoring agents and its preparation method, as well as the application of the base material in the compound preparation of low-fogging leather fatliquoring agents. Background Technology

[0002] Fatliquoring agents are among the most widely used leather chemicals in the leather industry. They typically consist mainly of active substances, neutral oils, auxiliaries, and solvents. Their function is to penetrate the raw leather into the leather body through the fatliquoring process under mechanical force, thereby increasing the leather's softness and imparting good physical and mechanical properties. The main components of fatliquoring agents are active substances and neutral oils. During the fatliquoring process, the active substances, under the action of mechanical force and heat, highly emulsify the neutral oil into latex particles of different particle sizes. These particles then penetrate into the collagen fibers of the leather under mechanical force, coating the surface of the collagen fibers and forming an "oil film." Subsequently, under the action of acid, the emulsification occurs, allowing the "oil film" to deposit on the surface of the collagen fibers, lubricating the fibers and preventing them from entangled, thus giving the leather good softness, mechanical properties, and fullness.

[0003] However, the volatile substances contained in leather can form a thin film after evaporation and aggregation. Especially when the binding strength between fatliquoring agent molecules and leather collagen fibers is relatively weak, the fatliquoring agent is prone to migrating out of the leather during heating, leading to an increase in the leather's fogging value. Fogging directly affects the safety and aesthetics of leather products and can pollute the air in enclosed environments. Particularly in the automotive industry, the volatile substances produced by fogging can condense on car windows, adversely affecting the driver's visibility. With the increasing use of leather in automotive interiors, the fogging problem is receiving more and more attention. To improve the safety of leather products, automotive manufacturers have established stringent standards for the fogging performance of leather. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a C21 diester-modified polyester base material for leather fatliquoring agents and its preparation method. The C21 diester-modified polyester base material has a specific polymer chain structure, containing high-molecular-weight hydroxyl compounds, and at least one of ester groups, polyether chains, sulfate ester salt groups, and carboxyl groups, thus solving the problems of low molecular weight, easy migration, and high atomization value of traditional fatliquoring materials. This invention further provides the application of this polyester base material in the preparation of composite synergistic leather fatliquoring agents.

[0005] The first aspect of this invention provides a C21 diacid ester-modified polyester base material for use as a leather fatliquoring agent, which is prepared by sequentially subjecting the esterification reaction product of C21 diacid and hydroxyl-containing compound to a sulfation reaction and a strong base neutralization reaction. The polymer backbone of the C21 diacid ester-modified polyester base material contains carboxylic acid ester bond connecting units formed by the reaction of C21 diacid and hydroxyl-containing compound. The weight average molecular weight of the hydroxyl-containing compound is 500-3000, and it is selected from at least one of polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene oxide-polypropylene oxide block copolymer, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer. The C21 diacid and the hydroxyl-containing compound undergo an esterification reaction in the presence of a catalyst.

[0006] Preferably, the catalyst is p-toluenesulfonic acid, and the relative mass ratio of each raw material in the preparation of the C21 diester-modified polyester base material is as follows: 24–32 parts of C21 dicarboxylic acid, 48–56 parts of hydroxyl-containing compounds, 0.4–1.3 parts of p-toluenesulfonic acid, and 16–22 parts of concentrated sulfuric acid.

[0007] A second aspect of the present invention provides a method for preparing a C21 diester-modified polyester base material for use as a leather fatliquoring agent, comprising the following steps: (1) Esterification reaction: C21 dicarboxylic acid, hydroxyl-containing compound and catalyst are added to the reaction vessel. The catalyst is dissolved under the protection of a non-reactive protective gas. Then the mixture is heated to 150-160℃ to carry out the esterification reaction. The heating is stopped when the acid value drops to below 30 mg KOH / g to obtain the esterification product. The non-reactive protective gas can be nitrogen. (2) Sulphation reaction: Cool the esterification reaction product obtained in step (1) to below 40°C, and continuously and uniformly add concentrated sulfuric acid. The addition time is 3 to 5 hours, and the temperature is controlled not to exceed 40°C during the addition process. After the addition of concentrated sulfuric acid is completed, continue to stir and keep warm at a temperature not higher than 40°C until the iodine value is less than or equal to 14 g I2 / 100g, and obtain the sulfation reaction product. (3) Neutralization reaction: The sulfation reaction product obtained in step (2) is neutralized to pH 6.5-7.5 with a strong alkaline solution to obtain C21 diester esterified modified polyester base material.

[0008] Preferably, the amounts of the C21 dicarboxylic acid, hydroxyl-containing compound, catalyst, and concentrated sulfuric acid, in parts by mass, are 22-23:48-56:0.4-1.3:16-22.

[0009] In this invention, C21 diacid (cyclic aliphatic diacid) and hydroxyl-containing compounds (such as polyether) are used as raw materials. The mixture is first esterified, then sulfated and neutralized to obtain a polyester base material containing multiple functional groups such as ester groups, polyether chains (EO / PO), sulfate ester salt groups (-OSO3Na, -SO3Na) and carboxyl groups. This polyester base material is an anionic, combined, multifunctional synthetic fatliquoring agent and can be synergistically compounded with ultra-low dosage white oil (as a functional regulator rather than the main base oil) and antioxidants and preservatives.

[0010] In one embodiment of the present invention, the weight-average molecular weight of the hydroxyl-containing compound is 500 to 3000, and is selected from at least one of polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene oxide-polypropylene oxide block copolymer, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer.

[0011] In one embodiment of the present invention, the catalyst is p-toluenesulfonic acid; and during the esterification reaction in step (1), the water generated in the reaction is continuously removed from the reaction system.

[0012] In one embodiment of the present invention, in step (2), the sulfation reaction is typically kept at a temperature of 8 hours or more; if the iodine value is still greater than 14 g I2 / 100g after the temperature is kept at a temperature, the reaction time is extended or concentrated sulfuric acid is added to continue the reaction until the iodine value is less than or equal to 14 g I2 / 100g.

[0013] In this invention, the process parameters of the sulfation reaction (temperature controlled below 40°C, feeding time 3-5 hours, and iodine value less than or equal to 14g I2 / 100g as the reaction endpoint) have a crucial impact on product performance. Specifically: Strictly controlling the sulfation temperature below 40℃ can effectively prevent the degradation and chain breakage of polyether segments under high temperature and strong acid environment, and at the same time prevent the hydrolysis of ester bonds in C21 diester esterification products, thereby ensuring the complete molecular structure and high molecular weight characteristics of polyester base material. If the sulfation temperature is raised to above 50℃, the polyether segments will degrade severely, the molecular weight of the product will decrease, the stability of the emulsion and the bonding strength with leather will be significantly deteriorated, and the fogging value will increase significantly. The feeding time should be controlled within the range of 3 to 5 hours to ensure that concentrated sulfuric acid and esterification products can fully and evenly contact and react, avoiding local overheating and side reactions. If the feeding time is shortened to less than 1 hour, the local temperature will be too high, resulting in a darker product color, an increase in side reactions, and a decrease in the emulsification stability of the product. Using an iodine value of less than or equal to 14g I2 / 100g as the endpoint of the sulfation reaction ensures that the carbon-carbon double bonds on the C21 dicarboxylic acid ring are fully sulfated, introducing sufficient sulfate ester salt groups (-OSO3Na, -SO3Na), thereby endowing the polyester base material with excellent self-emulsifying ability, strong bonding with leather fibers, and low fogging performance. If the iodine value is too high (e.g., >20g I2 / 100g), the degree of sulfation is insufficient, resulting in poor self-emulsifying ability, low bonding with leather, and high fogging value.

[0014] In one embodiment of the present invention, in step (1), a C21 dicarboxylic acid, a hydroxyl-containing compound, and a catalyst are sequentially added to a reaction vessel.

[0015] In one embodiment of the present invention, the strong alkaline solution in step (3) is a sodium hydroxide solution with a mass concentration of 25-30%.

[0016] The third aspect of the present invention provides a composite synergistic leather fatliquoring agent, comprising, by weight, 84-90 parts of the above-mentioned C21 diester-modified polyester base material, and a compound component; by weight, the compound component comprises: 8-12 parts of white oil, 0.4-0.9 parts of antioxidant, and 1.6-3.3 parts of preservative.

[0017] Preferably, in some embodiments, the white oil is 100# white oil; the antioxidant is a hindered phenolic antioxidant or an aromatic amine antioxidant; and the preservative is at least one of quaternary ammonium salts, isothiazolinones, aldehydes, guanidines, and organosulfur preservatives.

[0018] A fourth aspect of the present invention provides a method for preparing the above-mentioned composite synergistic leather fatliquoring agent, comprising the following steps: The C21 diester-modified polyester base material is heated to 55-65°C, white oil and antioxidant are added, and stirred for 1.5-2.5 hours. Then the temperature is lowered to below 50°C, and preservatives are added and stirred to obtain the composite synergistic leather fatliquoring agent.

[0019] In one embodiment of the present invention, the white oil is 100# white oil.

[0020] In one embodiment of the present invention, the antioxidant is a hindered phenolic antioxidant or an aromatic amine antioxidant; the preservative is at least one of quaternary ammonium salts, isothiazolinones, aldehydes, guanidines, and organosulfur preservatives.

[0021] In one embodiment of the present invention, the stirring time after adding the preservative in step (4) is more than 1 hour.

[0022] This invention uses C21 diacid and hydroxyl-containing compounds (polyethers) as raw materials. First, an esterification reaction is carried out to obtain the esterified product, followed by a sulfation reaction with concentrated sulfuric acid to finally obtain a novel polyester base material. This polyester base material is an anionic, bound, multifunctional synthetic fatliquoring agent. Its molecular structure has multiple functional characteristics: the long-chain C21 structure in the molecule imparts excellent lubricity, softness, and oily feel to leather; the polyether segments in the molecule ensure good emulsification and dispersibility, penetration performance, and electrolyte resistance, making it suitable for wet leather processing systems; the -SO3 group introduced into the molecule... - -OSO3 - The presence of polar groups such as -COOH allows it to form strong complexes or ionic bonds with metal ions in chrome-tanned leather, significantly improving the binding strength and migration resistance of the fatliquoring agent within the leather. Simultaneously, its high molecular weight and multi-branched structure can also impart certain filling and retanning effects, resulting in fuller, firmer leather with superior physical properties. Because polyester base molecules have high binding strength to leather and are not easily migrated, their ester groups and polyether chains can tightly bind with collagen fibers. They are not easily volatilized at high temperatures and do not release oil blooms, thus producing low-fogging, migration-resistant leather fatliquoring agents suitable for high-end leathers such as automotive leather and furniture leather.

[0023] Furthermore, white oil is a commonly used base oil in leather fatliquoring systems, primarily serving as a lubricating and softening agent, providing softness, lubricity, and hand feel to the finished leather. However, it lacks the ability to bind with leather collagen and requires emulsifiers or reactive components for stable retention. The polyester base material described in this invention has a unique molecular structure, containing both polyether segments (EO) and sulfate ester groups (-OSO3Na, -SO3Na), thus exhibiting strong self-emulsifying ability. It can form a small-particle-size, stable, acid-, alkali-, hard water-, and chromium-salt-resistant emulsion with white oil, directly penetrating deep into the leather and into the collagen fibers. It is particularly noteworthy that in preparing a compound synergistic leather fatliquoring agent through a compounding method, this invention uses an extremely low amount of white oil (10-15 parts by weight) as a functional regulator, rather than using it as a major base component in large quantities as in traditional fatliquoring agents. In this invention, when the amount of white oil is too low (below 10 parts by weight), the finished leather lacks sufficient lubricity and softness; when the amount of white oil is too high (exceeding 15 parts by weight, especially reaching the conventional level of 30 parts by weight or more for traditional fatliquoring agents), because white oil has no chemical bonding ability with leather collagen fibers, excessive white oil easily migrates and volatilizes at high temperatures, resulting in a significant increase in the atomization value, which offsets the low atomization advantage of the polyester base material itself. Therefore, this invention controls the amount of white oil within the range of 10-15 parts by weight, achieving the optimal synergistic effect of "combined polar fatliquoring agent + non-polar softening oil" between the polyester base material and white oil.

[0024] Using the polyester base material designed with specific molecules according to this invention, after being compounded with a small amount of white oil, a synergistic system of "combined polar fatliquoring agent + non-polar soft oil" can be formed technically, thereby constructing a composite synergistic leather fatliquoring agent with excellent comprehensive performance.

[0025] The fifth aspect of this invention provides the application of the above-mentioned composite synergistic leather fatliquoring agent in the leather fatliquoring process.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through polymer structure design, a polyester polymer matrix was successfully constructed by esterification-sulfation reaction of C21 diacid with a hydroxyl-containing compound of a specific molecular weight. The hydroxyl-containing compound, with a weight-average molecular weight of 500-3000, is selected from at least one of polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene oxide-polypropylene oxide block copolymer, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer. Compared with traditional small-molecule fatliquoring agents, this matrix has a higher molecular weight, stronger intermolecular forces, and significantly improved thermal stability.

[0027] 2. A method for preparing C21 diacid-modified polyester base material and a composite synergistic leather fatliquoring agent is provided. Using C21 diacid derived from natural unsaturated fatty acids and polyether-based hydroxyl-containing compounds as main raw materials, the fatliquoring agent is prepared through an esterification-sulfation-neutralization-compounding process. The process is simple, the conditions are mild, and it is easy to implement industrially. Furthermore, compared to the traditional sulfation process, which requires excessive concentrated sulfuric acid and multiple washes with large amounts of saturated brine (generating large amounts of acidic, high-salt wastewater), the preparation process of the composite synergistic leather fatliquoring agent provided by this invention is more environmentally friendly, with less waste discharge.

[0028] 3. The method for preparing C21 diacid acid modified polyester base material provided by the present invention directly sulfates the carbon-carbon double bond on the C21 diacid ring through sulfation reaction, and uses an iodine value of less than or equal to 14 g I2 / 100g as a clear reaction endpoint criterion. The reaction endpoint is controllable and the product quality is stable. In addition, the sulfation reaction temperature is strictly controlled below 40℃ to avoid polyether segment degradation and ester bond hydrolysis, and to ensure the integrity of the product molecular structure.

[0029] 4. The composite synergistic leather fatliquoring agent provided by this invention has low atomization performance, and the ester groups, polyether chains, and multiple polar groups (-SO3) in the polyester base molecule... - -OSO3 -The α-COOH group can tightly bind with metal ions in leather collagen fibers and chrome-tanned leather, exhibiting high binding strength and resistance to migration. It is also non-volatile and does not release oil bloom at high temperatures, significantly reducing the fogging value of the finished leather. As shown in the examples, the fogging value of the finished leather treated with the fatliquoring agent of this invention is as low as 1.1–1.8 mg / kg, far lower than the comparative example (4.3–42.1 mg / kg), meeting the stringent environmental requirements for low fogging in automotive interior leather and other products.

[0030] 5. The composite synergistic leather fatliquoring agent provided by this invention exhibits excellent resistance to yellowing, light, and heat: The unique cycloalkane structure of the C21 diacid endows the product with good antioxidant properties. In the subsequent chemical modification of the raw materials used in this invention, almost all unsaturated bonds are converted into saturated chemical bonds. Using an iodine value less than or equal to 14 g I2 / 100g as a clear reaction endpoint criterion, the light and heat resistance properties are significantly improved. The finished leather exhibits resistance to high-temperature yellowing (120℃, 24 hours) and sun lamp yellowing (24 hours) at levels 3-4. Finished leather prepared using the composite synergistic leather fatliquoring agent provided by this invention exhibits a comfortable and natural oily and full-bodied feel on the surface, a delicate and soft hand texture, and low odor (level 2, odorless).

[0031] 6. The composite synergistic leather fatliquoring agent product provided by this invention possesses both excellent emulsification and dispersibility, as well as good penetration. When applied to the leather fatliquoring process, this fatliquoring agent exhibits uniform penetration and dispersion, good emulsion stability, and strong process adaptability. The resulting finished leather exhibits low fogging, resistance to yellowing, excellent hand feel, and outstanding overall performance. It is particularly suitable for high-end leathers such as automotive leather and furniture leather, which require low fogging and high overall quality, and has broad application prospects.

[0032] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Detailed Implementation

[0033] Traditional leather fatliquoring agents are mostly based on natural oils, mineral oils, and their sulfonated and sulfonated products. They generally suffer from poor light resistance, easy oxidation and yellowing, weak bonding with leather fibers, easy migration and precipitation forming oil blooms, and easy volatilization and fogging at high temperatures. Furthermore, some products have poor biodegradability and insufficient emulsification stability, making it difficult to meet the requirements of high-end leather for low fogging, yellowing resistance, high bonding strength, and environmental safety. A deeper analysis reveals that the root cause of these problems lies in the fact that the core components of existing fatliquoring agents are mostly small molecules or oligomers with low molecular weights, resulting in limited binding sites with leather fibers, leading to poor thermal stability and easy migration. Therefore, developing a polyester polymer base material with a higher molecular weight and containing specific functional groups is key to solving these problems.

[0034] In the existing technology, there are reports of preparing fatliquoring agents from polyether, mineral oil, and natural oil raw materials through sulfonation, sulfation, esterification, and other modifications. For example, some schemes use long-chain fatty alcohol polyoxypropylene ether as raw material, which is sulfonated with SO3 to obtain sulfate, esterified with maleic anhydride and sulfite to obtain succinic acid monoester sulfonate, and then compounded with nonionic emulsifier and mineral oil to obtain a yellowing-resistant fatliquoring agent; some schemes use mineral oil, fatty alcohol polyoxyethylene ether, and maleic anhydride as raw materials to obtain a light-resistant composite fatliquoring agent through esterification and sulfite treatment; some schemes use trimethylolpropane fatty acid ester, sorbitan ester, and maleic anhydride to obtain a synthetic fatliquoring agent through esterification and sulfite treatment, and then compounded with the esterification products of dimer acid and polyethylene glycol; and some schemes use mineral oil, oleic acid mono / diglycerides, and natural oils to obtain a sulfated fatliquoring agent through concentrated sulfuric acid sulfation.

[0035] However, in practical applications, the aforementioned fatliquoring agents often address one defect while simultaneously revealing other performance shortcomings that cannot be simultaneously resolved, or even introducing new problems. Existing products generally suffer from the following deficiencies: they are primarily composed of mineral oil or natural oils, requiring large quantities and exhibiting weak bonding with leather fibers; they are prone to migration and volatilization at high temperatures, resulting in high atomization values; natural oil molecules contain numerous double bonds, making them susceptible to oxidation, yellowing, and off-odors; they also exhibit poor compatibility with leather fibers, insufficient high-temperature stability, poor emulsification and electrolyte resistance, and limited functionality, making it difficult to simultaneously meet the comprehensive requirements of high-grade leather in terms of low atomization, resistance to yellowing, high bonding strength, good hand feel, physical properties, and environmental friendliness. Therefore, developing a leather fatliquoring agent with low atomization values ​​and excellent overall performance is of significant practical importance.

[0036] Therefore, developing a polyester base material with controllable molecular structure, suitable weight-average molecular weight, and multiple active groups, and using it to prepare a composite synergistic leather fatliquoring agent, is of great practical significance.

[0037] Based on the above analysis, this invention provides a C21 diacid esterified modified polyester base material, its preparation method, and its application in leather fatliquoring agents. The preparation method includes the following steps: first, using C21 diacid and a hydroxyl-containing compound as raw materials, an esterification reaction is carried out under the action of a catalyst; then, a sulfation reaction is carried out with concentrated sulfuric acid; after the reaction, the mixture is neutralized to neutrality with a strong alkaline solution to obtain the polyester base material. When the catalyst is p-toluenesulfonic acid, the raw materials, by mass parts, are: C21 diacid 24-32, hydroxyl-containing compound 48-56, p-toluenesulfonic acid 0.4-1.3, and concentrated sulfuric acid 16-22. The hydroxyl-containing compound is selected from at least one of polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene oxide-polypropylene oxide block copolymer, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer. This invention also discloses a composite leather fatliquoring agent comprising the aforementioned polyester base material, white oil, antioxidant, and preservative. This preparation method is environmentally friendly. When the resulting fatliquoring agent is applied to the fatliquoring treatment of leather, the finished leather has a low atomization value (as low as 1.1 to 1.8 mg / kg), a full oily and foamy surface, a delicate and soft hand feel, and excellent light resistance and heat stability. Its comprehensive performance is outstanding and it is suitable for high-end leathers such as automotive leather and furniture leather.

[0038] In this document, the range expressed as "from one value to another" is a concise way of representing a range to avoid listing all the values ​​in that range in the specification. Therefore, the description of a particular range of values ​​covers any value within that range as well as the smaller range of values ​​defined by that value, just as if the arbitrary value and the smaller range of values ​​were explicitly stated in the specification.

[0039] In this application, unless otherwise stated, the use of "or" means "and / or". In the case of multiple dependent claims, "or" is used only in alternatives to refer to more than one of the aforementioned independent or dependent claims.

[0040] C21 dicarboxylic acids, also known as C21 dicarboxylic acids or cyclic aliphatic dicarboxylic acids, are long-chain aliphatic dicarboxylic acids obtained from natural unsaturated fatty acids through addition, cyclization, and carboxylation reactions. Their molecular backbone contains 21 carbon atoms, and their structural formula is as follows:

[0041] C21 dicarboxylic acid is a liquid, 21-carbon monocyclic dicarboxylic acid prepared from vegetable oil fatty acids. Although it has a large molecular weight, it is a pale yellow to colorless viscous liquid at room temperature. It exhibits low volatility, good thermal stability, lubricity, and surface activity. It also possesses excellent biodegradability, hard water resistance, and compatibility with leather fibers and polymer materials, making it suitable as a surfactant and chemical intermediate. Its unique cycloalkane structure effectively enhances the oxidation and yellowing resistance of the synthesized products, while the long alkyl chain imparts good softness, hydrophobicity, and lubrication. The dicarboxyl group structure allows it to undergo condensation reactions with polyols, amines, and other compounds. Simultaneously, the double bonds on the ring can undergo sulfation reactions to introduce new groups. This process can endow the compound with different physical and chemical properties, such as increased solubility, improved penetration, enhanced self-emulsification ability, and improved adhesion to leather.

[0042] The present invention will be further described in detail below with reference to specific embodiments. In the following embodiments, unless otherwise specified, the amount of raw materials used is by mass.

[0043] The uniform application process conditions for leather fatliquoring treatment in the following experimental examples are as follows: Take chrome-tanned blue wet leather, add fatliquoring agent at a dosage of 8% of the leather weight, add water (200% of the leather weight, temperature 50℃) to a drum, add the fatliquoring agent, rotate the drum for 60 minutes, then add formic acid (1.5% of the leather weight) for fixation for 30 minutes, remove from the drum, mount, and dry to obtain the finished leather. All examples and comparative examples use the same batch of chrome-tanned blue wet leather and the same process conditions.

[0044] The following are explanations of the performance evaluation scoring criteria: Foam texture rating criteria (5-point scale): The average score is calculated based on independent ratings from 10 trained volunteers. 5 points - extremely full foam texture, excellent elasticity; 4 points - full foam texture, good elasticity; 3 points - average foam texture, acceptable elasticity; 2 points - poor foam texture, insufficient elasticity; 1 point - very poor foam texture, stiff.

[0045] Oiliness (moisturization) rating criteria (5-point scale): The average score is calculated based on independent ratings from 10 trained volunteers. 5 points - Excellent oiliness, smooth and delicate touch; 4 points - Good oiliness, smooth touch; 3 points - Average oiliness; 2 points - Poor oiliness, slightly dry; 1 point - Very poor oiliness, dry and rough.

[0046] Odor rating criteria: According to QB / T2725-2005 "Determination of odor of leather", Grade 1 - no odor; Grade 2 - slight odor, but no odor; Grade 3 - obvious odor, but no irritating odor; Grade 4 - irritating odor; Grade 5 - strong irritating odor.

[0047] Example 1 This embodiment provides a composite synergistic leather fatliquoring agent, and the preparation method of the composite synergistic leather fatliquoring agent is as follows: (1) Esterification reaction: At room temperature, 35 kg of C21 dicarboxylic acid, 65 kg of polyethylene glycol (brand name PEG-1000) and 1 kg of p-toluenesulfonic acid are added to the reaction vessel in sequence. Under nitrogen protection, the temperature is controlled and heated to completely dissolve the p-toluenesulfonic acid. Then, the temperature is heated to 150-160℃ for esterification reaction. During the reaction, water is continuously separated. The acid value of the system gradually decreases from above 110 mg KOH / g. When the acid value drops to below 30 mg KOH / g, the heating is stopped, and the esterification reaction product is obtained.

[0048] (2) Sulphation reaction: Cool the esterification reaction product to below 40°C, and continuously and evenly add 25 kg of concentrated sulfuric acid (about 13.7 L, corresponding to about 25 kg) for 3 hours. During the addition process, control the temperature not to exceed 40°C. After the addition is complete, continue stirring and keeping warm at 40°C for 8 hours. Take a sample to determine the iodine value. If the iodine value is greater than 14 g I2 / 100g, extend the reaction time or add an appropriate amount of concentrated sulfuric acid to continue the reaction until the iodine value is less than 14 g I2 / 100g, and obtain the sulfation reaction product.

[0049] (3) Neutralization reaction: The sulfation reaction product is neutralized to pH 6.5-7.5 with 30% sodium hydroxide solution to obtain polyester base material.

[0050] (4) Compounding: Heat the polyester base material to 60°C, add 12kg of 100# white oil and 0.7kg of BHT (hindered phenolic antioxidant), stir at 60°C for 2 hours, cool down to below 50°C, add 3kg of BIT (isothiazolinone preservative), stir for 1 hour, and the compound synergistic leather fatliquoring agent is obtained.

[0051] Example 2 This embodiment provides a composite synergistic leather fatliquoring agent. The preparation method of this composite synergistic leather fatliquoring agent in this embodiment differs from that in Example 1 in that: in this embodiment, 65 kg of polyethylene glycol (PEG-1000) in Example 1 is replaced with 65 kg of polyethylene oxide-polypropylene oxide block copolymer (brand name P103, weight average molecular weight of about 1000). The remaining operations are the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0052] Example 3 This embodiment provides a composite synergistic leather fatliquoring agent. The preparation method of this composite synergistic leather fatliquoring agent in this embodiment differs from that in Example 1 in that: 65 kg of polyethylene glycol (PEG-1000, weight average molecular weight of about 1000) in Example 1 is replaced with 65 kg of polyethylene glycol monomethyl ether (brand name mPEG-1000, weight average molecular weight of about 1000). The remaining operations are the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0053] Example 4 This embodiment provides a composite synergistic leather fatliquoring agent. The preparation method of this composite synergistic leather fatliquoring agent in this embodiment differs from that in Example 1 in that: 65 kg of polyethylene glycol (PEG-1000) in Example 1 is replaced with 65 kg of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (brand name P181, weight average molecular weight of about 1000). The remaining operations are the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0054] Example 5 This embodiment provides a composite synergistic leather fatliquoring agent. The preparation method of this composite synergistic leather fatliquoring agent in this embodiment differs from that in Example 1 in that: 65 kg of polyethylene glycol (PEG-1000, weight average molecular weight of about 1000) in Example 1 is replaced with 65 kg of polyethylene glycol (PEG-600, weight average molecular weight of about 600). The remaining operations are the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0055] Example 6 This embodiment provides a composite synergistic leather fatliquoring agent. The preparation method of this composite synergistic leather fatliquoring agent in this embodiment differs from that in Example 1 in that: 65 kg of polyethylene glycol (PEG-1000, weight average molecular weight of about 1000) in Example 1 is replaced with 65 kg of polyethylene glycol (PEG-2000, weight average molecular weight of about 2000). The remaining operations are the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0056] Example 7 This embodiment provides a compound synergistic leather fatliquoring agent.

[0057] In this embodiment, the amounts of each raw material by mass are as follows: 30 parts of C21 dicarboxylic acid, 70 parts of hydroxyl-containing compound, 1 part of catalyst, 22 parts of concentrated sulfuric acid, 12 parts of white oil, 0.7 parts of antioxidant, and 3 parts of preservative.

[0058] The difference between the preparation method of the composite synergistic leather fatliquoring agent in this embodiment and that in Example 1 is as follows: the amount of C21 dicarboxylic acid is 30 kg, the amount of hydroxyl compound (PEG-1000) is 70 kg, the amount of p-toluenesulfonic acid catalyst is 1 kg, the amount of concentrated sulfuric acid is 22 kg, the amount of white oil is 12 kg, the amount of antioxidant BHT is 0.7 kg, and the amount of preservative BIT is 3 kg. The remaining operations are the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0059] Example 8 This embodiment provides a composite synergistic leather fatliquoring agent. In this embodiment, the amounts of each raw material by weight are as follows: 40 parts of C21 diacid, 60 parts of hydroxyl-containing compound, 1 part of catalyst, 28 parts of concentrated sulfuric acid, 12 parts of white oil, 0.7 parts of antioxidant, and 3 parts of preservative.

[0060] The difference between the preparation method of the composite synergistic leather fatliquoring agent in this embodiment and that in Example 1 is as follows: the amount of C21 dicarboxylic acid is 40 kg, the amount of hydroxyl compound (PEG-1000) is 60 kg, the amount of catalyst p-toluenesulfonic acid is 1 kg, the amount of concentrated sulfuric acid is 28 kg, the amount of white oil is 12 kg, the amount of antioxidant BHT is 0.7 kg, and the amount of preservative BIT is 3 kg. The remaining operations are the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0061] Example 9 This embodiment provides a composite synergistic leather fatliquoring agent. The difference between the preparation method of the composite synergistic leather fatliquoring agent in this embodiment and that in Example 1 is that the antioxidant is replaced by 0.7 kg BHT (hindered phenol) with 0.7 kg N,N'-diphenyl-p-phenylenediamine (aromatic amine antioxidant). The rest of the operation is the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0062] Example 10 This embodiment provides a composite synergistic leather fatliquoring agent. The difference between the preparation method of the composite synergistic leather fatliquoring agent in this embodiment and that in Example 1 is that the preservative is replaced by 3 kg of BIT (isothiazolinone) with 3 kg of glutaraldehyde (glutaraldehyde preservative). The rest of the operation is the same as in Example 1, and the composite synergistic leather fatliquoring agent is obtained.

[0063] Comparative Example 1 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that: 35 kg of C21 dicarboxylic acid is replaced with 20 kg of maleic acid, the amount of hydroxyl compound (PEG-1000) is 80 kg, and the amount of catalyst p-toluenesulfonic acid is 1 kg. The components are added to the reaction vessel in sequence for esterification reaction, and then sulfated, neutralized, and compounded to obtain the fatliquoring agent.

[0064] Comparative Example 2 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that: the hydroxyl-containing compound is replaced with 50 kg of isomeric decaol (small molecule alcohol), the amount of C21 dicarboxylic acid is 50 kg, the amount of catalyst p-toluenesulfonic acid is 1 kg, and they are added to the reaction vessel in sequence for esterification reaction, followed by sulfation, neutralization, and compounding to obtain the fatliquoring agent.

[0065] Comparative Example 3 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that the product of Example 1, which only underwent esterification, is not sulfated but is directly neutralized to neutral with 30% sodium hydroxide solution, and then compounded to obtain the fatliquoring agent.

[0066] Comparative Example 4 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that the amount of white oil used is increased from 12 kg to 40 kg (that is, about 40 parts by mass, simulating the conventional formula in traditional fatliquoring agents where white oil is used as the main base oil in large quantities). The remaining operations are the same as in Example 1, and the fatliquoring agent is obtained.

[0067] Comparative Example 5 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that the amount of white oil used is reduced from 12 kg to 5 kg (i.e., about 5 parts by mass), while the remaining operations are the same as in Example 1, and the fatliquoring agent is obtained.

[0068] Comparative Example 6 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that: the amount of C21 dicarboxylic acid is 20 kg, the amount of hydroxyl-containing compound (PEG-1000) is 80 kg (i.e., the ratio is 20:80), the amount of p-toluenesulfonic acid catalyst is 1 kg, the amount of concentrated sulfuric acid is 20 kg, the amount of white oil is 12 kg, the amount of antioxidant BHT is 0.7 kg, the amount of preservative BIT is 3 kg, and the remaining operations are the same as in Example 1 to obtain the fatliquoring agent.

[0069] Comparative Example 7 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that: the amount of C21 dicarboxylic acid is 50 kg, the amount of hydroxyl-containing compound (PEG-1000) is 50 kg (i.e., the ratio is 50:50), the amount of p-toluenesulfonic acid catalyst is 1 kg, the amount of concentrated sulfuric acid is 30 kg, the amount of white oil is 12 kg, the amount of antioxidant BHT is 0.7 kg, the amount of preservative BIT is 3 kg, and the remaining operations are the same as in Example 1 to obtain the fatliquoring agent.

[0070] Comparative Example 8 This comparative example provides a fatliquoring agent. The preparation method of this fatliquoring agent differs from that of Example 1 in that the sulfation reaction temperature is controlled at 55-60°C (instead of below 40°C), the feeding time is 1 hour (instead of 3 hours), and the remaining operations are the same as in Example 1, thus obtaining the fatliquoring agent.

[0071] Experimental Example The fatliquoring agents obtained in Examples 1-10 and Comparative Examples 1-8 were compared in their application to leather fatliquoring.

[0072] According to GB / T 16899-2010 "Determination of Fogging Properties of Leather and Fur", QB / T 4681-2014 "Determination of Yellowing Resistance of Leather in Physical and Mechanical Tests", and QB / T 2727-2017 "Color Fastness Test of Leather - Light Fastness", the fogging value, high temperature yellowing resistance and sunlight lamp yellowing resistance were determined respectively. Odor was determined according to QB / T2725-2005 "Determination of Odor in Leather"; The foamy and oily (moisturizing) sensations were assessed by 10 trained volunteers who independently rated the sensations using the 5-point scale mentioned above, and the average score was taken.

[0073] Emulsion stability tests were conducted by heating a 10% emulsion at 50°C for 24 hours and then centrifuging it at 4000 rpm for 15 minutes to observe whether the emulsion separated into layers.

[0074] The results are shown in Tables 1 and 2.

[0075] Table 1 Example 1 1.8 Level 3-4 Level 3-4 Level 2 Odorless 3.7 3.7 Example 2 1.3 Level 3-4 Level 3-4 Level 2 Odorless 4.0 4.2 Example 3 1.1 Level 3-4 Level 3-4 Level 2 Odorless 3.7 3.8 Example 4 1.7 Level 3-4 Level 3-4 Level 2 Odorless 3.8 4.0 Example 5 1.4 Level 3-4 Level 3-4 Level 2 Odorless 3.6 3.8 Example 6 1.7 Level 3-4 Level 3-4 Level 2 Odorless 3.8 3.7 Example 7 1.5 Level 3-4 Level 3-4 Level 2 Odorless 3.7 3.8 Example 8 1.7 Level 3-4 Level 3-4 Level 2 Odorless 3.6 3.6 Example 9 1.8 Level 3-4 Level 3-4 Level 2 Odorless 3.8 3.7 Example 10 1.6 Level 3-4 Level 3-4 Level 2 Odorless 3.7 3.6 Comparative Example 1 10.6 Level 3-4 Level 3-4 Level 3 has an odor 3.0 3.1 Comparative Example 2 42.1 Level 3-4 Level 3-4 Level 3.5 has an odor 3.4 3.8 Comparative Example 3 4.3 Level 2 Level 1-2 Level 3: Slightly unpleasant odor 3.1 3.1 Comparative Example 4 4.0 Level 3-4 Level 3-4 Level 3: Slightly unpleasant odor 3.2 3.3 Comparative Example 5 1.8 Level 3-4 Level 3-4 Level 2 Odorless 3.0 3.1 Comparative Example 6 2.1 Level 3-4 Level 3-4 Level 2 Odorless 2.8 2.7 Comparative Example 7 1.7 Level 3-4 Level 3-4 Level 2 Odorless 2.9 2.9 Comparative Example 8 5.8 Level 2-3 Level 2 Level 3 has an odor 3.1 3.0 Table 2 Comparison of emulsion properties, binding strength, and physical and mechanical properties Example 1 Stable and non-layered Stable and non-layered Example 2 Stable and non-layered Stable and non-layered Example 3 Stable and non-layered Stable and non-layered Example 4 Stable and non-layered Stable and non-layered Example 5 Stable and non-layered Stable and non-layered Example 6 Stable and non-layered Stable and non-layered Example 7 Stable and non-layered Stable and non-layered Example 8 Stable and non-layered Stable and non-layered Example 9 Stable and non-layered Stable and non-layered Example 10 Stable and non-layered Stable and non-layered Comparative Example 1 Stable and non-layered Stable and non-layered Comparative Example 2 Slightly layered Stable and non-layered Comparative Example 3 Slightly layered Layering Comparative Example 4 Slightly layered Slightly layered Comparative Example 5 Stable and non-layered Stable and non-layered Comparative Example 6 Stable and non-layered Stable and non-layered Comparative Example 7 Stable and non-layered Stable and non-layered Comparative Example 8 Slightly layered Slightly layered As shown in Table 1, the composite synergistic leather fatliquoring agent emulsion of this application is stable and, when applied to the leather fatliquoring process, produces finished leather with low atomization values ​​(≤1.8 mg / kg in all examples), significantly superior to Comparative Example 1 (10.6 mg / kg), which uses a small molecule unsaturated diacid to replace the C21 diacid; Comparative Example 2 (42.1 mg / kg), which uses a small molecule alcohol to replace the polyether; and Comparative Example 3 (4.3 mg / kg), which omits the sulfation step. Simultaneously, the finished leather exhibits excellent oiliness and foaminess, a delicate and soft hand feel, low odor, and superior lightfastness and heat stability (Comparative Example 3, lacking sulfation, shows significant deterioration in yellowing resistance). These advantages are attributed to the specific structure of the polyester base material used in this invention and its synergistic compounding with extremely low amounts of white oil.

[0076] In Comparative Example 1, maleic acid was used to replace C21 dicarboxylic acid. The resulting product had an increased atomization value of 10.6 mg / kg, and the odor was increased and the feel was reduced. This indicates that the unique long-chain cycloalkane structure of C21 dicarboxylic acid plays a key role in reducing atomization and improving feel.

[0077] Comparative Example 2, which replaced polyether-containing hydroxyl compounds with isomeric decaol, resulted in a significantly increased atomization value of 42.1 mg / kg, indicating that polyether segments play a key role in improving the bonding strength between polyester base material and leather, and reducing migration and atomization.

[0078] The product of Comparative Example 3 was esterified without sulfation. The resulting product had an increased atomization value of 4.3 mg / kg, and its high-temperature yellowing resistance decreased to level 2, its sun lamp yellowing resistance decreased to level 1-2, and its hand feel also decreased significantly. This indicates that the introduction of sulfate ester salt groups by the sulfation reaction is indispensable for improving self-emulsification ability, binding strength and overall performance. At the same time, the emulsion stability is slightly lacking.

[0079] Comparative Example 4 simulated a traditional fatliquoring agent formula with a large amount of white oil (40 parts). Since the excessive white oil has no chemical bonding ability with the leather collagen fiber, it migrates and volatilizes in large quantities at high temperature, resulting in an increase in atomization value. That is, excessive white oil will offset the low atomization advantage of polyester base material, and the emulsion stability is slightly worse.

[0080] Comparative Example 5 used too little white oil (5 parts). Although the atomization value was still low, the lubricity and softness of the finished leather were insufficient. The foaming and oiliness scores were significantly lower than those of the Example. That is, even too little white oil cannot meet the requirements for the feel of the finished leather.

[0081] Comparative Examples 6 and 7, with C21 dicarboxylic acid and hydroxyl-containing compound ratios of 20:80 and 50:50 respectively, yielded products with performance inferior to those of the Examples.

[0082] Comparative Example 8 uses a high-temperature (55-60°C) and rapid feeding (1 hour) sulfation process. The resulting product has a darker color, decreased emulsion stability, and increased atomization value. This demonstrates the key influence of the sulfation process parameters (temperature ≤40°C, feeding time 3-5 hours) of the present invention on product performance, while the emulsion stability is slightly lacking.

[0083] In summary, the aforementioned performance advantages of the composite synergistic leather fatliquoring agent prepared by the present invention are all attributed to the use of a polyester base material with a specific molecular structure and the synergistic compounding of the polyester base material with ultra-low dosage of white oil.

[0084] The above description discloses only preferred embodiments of the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to make good use of the invention. The present invention is limited only by the claims and their full scope and equivalents.

[0085] Under the guidance of the present invention and the above embodiments, those skilled in the art will readily foresee that all the raw materials or their equivalents, processing methods or their equivalents listed or exemplified in the present invention can achieve the present invention, and that the upper and lower limits and range values ​​of the parameters of each raw material and processing method can also achieve the present invention. Examples are not listed one by one here.

Claims

1. A C21 diester-modified polyester base material for use as a leather fatliquoring agent, characterized in that, The product is prepared by sequentially sulfation and strong base neutralization of the esterification reaction product of C21 diacid and hydroxyl-containing compound. The polymer backbone of the C21 diacid esterified modified polyester matrix contains carboxylic acid ester bond linkage units formed by the reaction of C21 diacid and hydroxyl-containing compound. The weight average molecular weight of the hydroxyl-containing compound is 500-3000, and it is selected from at least one of polyethylene glycol, polyethylene glycol monomethyl ether, polyethylene oxide-polypropylene oxide block copolymer, and polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer. The esterification reaction of C21 diacid and hydroxyl-containing compound is carried out in the presence of a catalyst.

2. The C21 diester-modified polyester base material for leather fatliquoring agents as described in claim 1, characterized in that, The catalyst is p-toluenesulfonic acid; the relative mass ratio of each raw material in the preparation of the C21 diester-modified polyester base material is as follows: 24–32 parts of C21 dicarboxylic acid, 48–56 parts of hydroxyl-containing compounds, 0.4–1.3 parts of p-toluenesulfonic acid, and 16–22 parts of concentrated sulfuric acid.

3. A method for preparing a C21 diester-modified polyester base material for leather fatliquoring agents as described in any one of claims 1-2, characterized in that, Includes the following steps: (1) Esterification reaction: C21 dicarboxylic acid, hydroxyl-containing compound and catalyst are added to the reaction vessel. The catalyst is dissolved under non-reactive protective gas conditions. Then the mixture is heated to 150-160℃ to carry out the esterification reaction. The heating is stopped when the acid value drops to below 30mg KOH / g to obtain the esterification reaction product. (2) Sulphation reaction: Cool the esterification reaction product obtained in step (1) to below 40°C, and continuously and uniformly add concentrated sulfuric acid. The addition time is 3 to 5 hours, and the temperature is controlled not to exceed 40°C during the addition process. After the addition of concentrated sulfuric acid is completed, continue to stir and keep warm at a temperature not higher than 40°C until the iodine value is less than or equal to 14 g I2 / 100g, and obtain the sulfation reaction product. (3) Neutralization reaction: The sulfation reaction product obtained in step (2) is neutralized to pH 6.5-7.5 with a strong alkaline solution to obtain C21 diester esterified modified polyester base material.

4. The method for preparing C21 diester-modified polyester base material for leather fatliquoring agents as described in claim 3, characterized in that, During the esterification reaction in step (1), the water generated in the reaction is continuously removed from the reaction system.

5. The method for preparing C21 diester-modified polyester base material for leather fatliquoring agents as described in claim 3, characterized in that, In step (2), the sulfation reaction is kept at a temperature of 8 hours or more. If the iodine value is still greater than 14 g I2 / 100g after the temperature is kept at a temperature, the reaction time is extended or concentrated sulfuric acid is added to continue the reaction until the iodine value is less than or equal to 14 g I2 / 100g.

6. The method for preparing C21 diester-modified polyester base material for leather fatliquoring agent as described in claim 3, characterized in that, In step (1), the C21 dicarboxylic acid, the hydroxyl-containing compound, and the catalyst are added sequentially to the reaction vessel.

7. The method for preparing C21 diester-modified polyester base material for leather fatliquoring agent as described in claim 3, characterized in that, The strong alkaline solution mentioned in step (3) is a sodium hydroxide solution with a mass concentration of 25-30%.

8. A compound synergistic leather fatliquoring agent, characterized in that, The product comprises, by weight, 84-90 parts of the C21 diester-modified polyester base material as described in any one of claims 1-2, and the compound components; The compound components, by weight, include: 8-12 parts white oil, 0.4-0.9 parts antioxidant, and 1.6-3.3 parts preservative.

9. A method for preparing the composite synergistic leather fatliquoring agent according to claim 8, characterized in that, Includes the following steps: The C21 diester-modified polyester base material is heated to 55-65°C, white oil and antioxidant are added, and stirred for 1.5-2.5 hours. Then the temperature is lowered to below 50°C, and preservatives are added and stirred to obtain the composite synergistic leather fatliquoring agent.

10. The application of the composite synergistic leather fatliquoring agent of claim 8 in the leather fatliquoring process.

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