Low-odor environment-friendly leather release finisher, preparation method and application thereof

Abstract

The present application belongs to the technical field of leather manufacturing, and particularly relates to a low-odor environment-friendly leather release finish, a preparation method and application thereof. The preparation method of the low-odor environment-friendly leather release finish comprises the following steps: S1, adding deionized water, water-based silicon wax emulsion and water-based polycarbonate polyurethane into a dispersion kettle to be stirred and dispersed to obtain a mixed solution; S2, adding a leveling agent and an organic amine additive into the mixed solution in step S1 to be stirred and mixed, adjusting the pH to 8-9, then adding a thickening agent to be uniformly mixed, and filtering to obtain the low-odor environment-friendly leather release finish. The finish can not only ensure less odor release, but also has good light yellow resistance and peeling strength, so that it is better applied in the leather field.

Description

Technical Field

[0001] This invention belongs to the technical field of leather manufacturing, specifically relating to a low-odor, environmentally friendly leather isolation coating agent, its preparation method, and its application. Background Technology

[0002] Leather finishing agents are treatment agents applied to the surface of leather. They are multi-component mixtures consisting of film-forming substances, coloring materials, additives, and solvents. The film-forming substances bind the other components evenly onto the leather surface, forming one or more thin films. They not only improve the appearance and style of leather, enhancing its aesthetics and quality, but also increase its durability and comfort.

[0003] To improve the utilization rate and uniformity of whole leather pieces, leather blanks typically undergo embossing and softening processes after base coating. Embossing involves shaping the leather coating under specific temperatures (mostly 90-150℃) and pressures. Softening, on the other hand, involves using a specialized leather drum under specific temperature and humidity conditions, employing mechanical operations such as high-altitude drops and tumbling to soften the leather. However, the high temperature and humidity environment can cause oils and other raw materials within the leather to leak out, and the friction between the leather blanks can lead to surface contamination of the coating. To prevent the base coating from being removed by the high-temperature metal plate and from being contaminated during the softening process, spraying a light-blocking agent is a necessary step. Currently, commonly used nitrocellulose emulsions have the advantages of rapid film formation, good high-temperature resistance, and low surface tack, making them the most commonly used light-blocking product in the leather industry. However, they contain a large amount of organic solvents, which produce a strong odor during use, affecting the environment and worker health. Furthermore, nitrocellulose molecules contain a large number of nitrate ester bonds, making them prone to yellowing under light or heat, directly impacting the color difference of light-colored leather products.

[0004] Currently, leather industry professionals are researching environmentally friendly light-blocking products. For example, Chinese patent (publication number CN106752974B) discloses an environmentally friendly nitrocellulose leather brightener and its preparation method. It uses alkyd resin, melamine-formaldehyde resin, and nitrocellulose, and uses organic solvents to dissolve the main components, reducing the amount of organic solvents used, but it is not completely environmentally friendly. Chinese patent (publication number CN109880504B) discloses a leather isolation layer coating agent, its preparation method, and leather. This invention patent uses isocyanate, diol, and chain extender to synthesize waterborne polyurethane, which is then mixed and reacted with waterborne epoxy resin to obtain a leather isolation layer coating agent. This isolation layer coating agent can be prepared without solvents or with only a small amount of organic solvents, and has no irritating odor and does not pollute the environment. However, its production process is complex, and there are currently no related commercially available products.

[0005] Currently used nitrocellulose latex, a common insulating material, has raw materials that are not easily soluble in water, requiring large amounts of solvents and plasticizers for solubility. Consequently, related products have a strong odor and high VOC content, impacting both the environment and worker health. Therefore, there is an urgent need for a low-odor, environmentally friendly leather insulating coating agent. When applied to leather, this agent provides excellent embossing and anti-sticking properties, good tumble softening and stain resistance, and also exhibits superior performance in terms of light resistance to yellowing, wet peel strength, and odor level. Summary of the Invention

[0006] The purpose of this invention is to provide a low-odor, environmentally friendly leather isolating coating agent, its preparation method, and its application. This invention first prepares a modified polycarbonate diol by mixing 1,4-butanediol, dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane), and dimethyl carbonate. Then, a waterborne polycarbonate polyurethane is synthesized using the modified polycarbonate diol and isophorone diisocyanate as raw materials. Next, an emulsification treatment is performed on a mixture of organosilicon wax, isotretinoin polyoxyethylene ether, Span 60, triethanolamine, and hot water to obtain a waterborne silicone wax emulsion. Finally, a coating agent is prepared using the waterborne polycarbonate polyurethane, the waterborne silicone wax emulsion, a thickener, organic amine additives, a leveling agent, and deionized water as raw materials. This method ensures minimal odor release while exhibiting good resistance to light yellowing and peel strength, making it more suitable for use in the leather industry.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a method for preparing a low-odor, environmentally friendly leather insulating coating agent, comprising the following steps: S1. Deionized water, waterborne silicone wax emulsion, and waterborne polycarbonate polyurethane are added to a dispersion vessel and stirred to disperse to obtain a mixture. S2. Add leveling agent and organic amine additive to the mixture described in step S1 and stir to mix. Adjust the pH to 8-9, then add thickener and mix well. Filter to obtain a low-odor environmentally friendly leather isolation coating agent.

[0008] As a preferred embodiment, the stirring and dispersion conditions in step S1 are: a rotation speed of 200~400 r / min and a time of 10~30 min.

[0009] As a preferred embodiment, the stirring and mixing conditions in step S2 are: a rotation speed of 400~600 r / min and a time of 10~20 min.

[0010] As a preferred embodiment, the components, by weight, include: 10-20 parts of waterborne polycarbonate polyurethane, 3-6 parts of waterborne silicone wax emulsion, 1-2 parts of thickener, 0.1-1 parts of organic amine additive, 0.1-1 parts of leveling agent, and 70-80 parts of deionized water.

[0011] As a preferred embodiment, the waterborne polycarbonate polyurethane can be in the following weight proportions: 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, or 20 parts, etc.

[0012] As a preferred embodiment, the water-based silicone wax emulsion may be present in 3, 4, 5, or 6 parts by weight, etc.

[0013] As a preferred embodiment, the thickener may be present in parts by weight of 1.0, 1.2, 1.4, 1.6, 1.8, or 2.0 parts, etc.

[0014] As a preferred embodiment, the organic amine auxiliaries may be present in weight parts of 0.1, 0.3, 0.7, or 1.0 parts, etc.

[0015] As a preferred embodiment, the leveling agent may be present in parts by weight of 0.1 parts, 0.3 parts, 0.7 parts, or 1.0 parts, etc.

[0016] As a preferred embodiment, the waterborne polycarbonate polyurethane is prepared by mixing 1,4-butanediol, dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane), and dimethyl carbonate to prepare a modified polycarbonate diol, and then using the modified polycarbonate diol and isophorone diisocyanate as raw materials to carry out a synthesis reaction to obtain the waterborne polycarbonate polyurethane.

[0017] As a preferred embodiment, the preparation steps of the modified polycarbonate diol are as follows: by weight, 280-300 parts of 1,4-butanediol and 40-50 parts of dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane) are added to a reaction vessel, followed by the addition of 0.06-0.08 parts of tetrabutyl titanate. After heating to 145-150°C, 400-420 parts of dimethyl carbonate are added. The reaction is then carried out at a temperature of 165-170°C and a vacuum of 200 Pa for 2-4 hours. After the reaction is completed, the modified polycarbonate diol is obtained by vacuum distillation.

[0018] As a preferred embodiment, the synthesis reaction steps are as follows: 40-50 parts by weight of modified polycarbonate diol and 20-30 parts by weight of isophorone diisocyanate are added to a reactor and subjected to a prepolymerization reaction at 70-75°C for 60-80 minutes. After cooling to 45°C, 1-2 parts by weight of acetone are added to adjust the viscosity. Then, 2-3 parts by weight of dimethylolpropionic acid, 4-5 parts by weight of 1,4-butanediol, 0.1-0.2 parts by weight of dibutyltin dilaurate, and 0.1-0.2 parts by weight of stannous octoate are added and reacted at 50-55°C for 4-6 hours. 1-2 parts by weight of hydroxyethyl methacrylate are added and reacted for 100-120 minutes. 1-2 parts by weight of triethylamine are added for neutralization reaction for 20-30 minutes. Finally, 90-100 parts by weight of deionized water are added for emulsification for 40-50 minutes, followed by rotary evaporation to obtain waterborne polycarbonate polyurethane.

[0019] This invention first uses tetrabutyl titanate as a transesterification catalyst to transesterify dimethyl carbonate with 1,4-butanediol and dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane) to obtain modified polycarbonate diol; then, the modified polycarbonate diol and isophorone diisocyanate are used in a synthesis reaction to prepare waterborne polycarbonate polyurethane; the polycarbonate polyurethane has strong molecular chain regularity and high cohesive energy, and has excellent heat resistance and compressive strength. At the same time, it has good film density and high polarity, and has good barrier ability against non-polar oils and small molecule additives. As an isolation layer, it can lock in the migration of the underlying material.

[0020] As a preferred embodiment, the aqueous silicone wax emulsion is prepared by mixing organosilicone wax, isotretinoin polyoxyethylene ether, Span 60, triethanolamine, and hot water, followed by emulsification treatment to obtain the aqueous silicone wax emulsion.

[0021] As a preferred embodiment, the emulsification process is as follows: by weight, 20-30 parts of silicone wax, 1-2 parts of isotridecyl polyoxyethylene ether, 1-2 parts of Span 60 and 2-4 parts of triethanolamine are added to a reaction vessel, heated to 75-85°C and stirred for 50-60 minutes, then 90-100 parts of hot water at 80°C are added, and the mixture is stirred at 80-100 r / min for 60-120 minutes. After cooling, the mixture is homogenized at 20-30 MPa for 5-10 minutes to obtain an aqueous silicone wax emulsion.

[0022] This invention involves emulsifying a mixture of organosilicon wax, isotridecyl alcohol polyoxyethylene ether, Span 60, triethanolamine, and hot water to obtain an aqueous silicone wax emulsion. The emulsion matrix has a Si-O-Si main-linked long alkyl side-chain structure, combining the low surface tension and excellent heat resistance of organosilicon polymers with a waxy feel, thus reducing the plastic feel of the coating. After film formation and drying, the silicone wax components migrate and distribute to the coating surface, constructing a hydrophobic and antifouling interface, providing excellent embossing release properties. Simultaneously, during the softening process of the preform, it prevents impurities from adhering to the coating. After sufficient softening, the surface silicone wax additive is largely consumed, without adversely affecting the interlayer adhesion of subsequent upper coatings.

[0023] As a preferred embodiment, the thickener is a water-based acrylic thickener or a water-based polyurethane thickener.

[0024] As a preferred embodiment, the mass ratio of the waterborne acrylic thickener to the waterborne polyurethane thickener is (1~3):1.

[0025] This invention uses a water-based acrylic thickener and a water-based polyurethane thickener as the thickening components of the system. By controlling the mass ratio of the two thickeners, a synergistic effect is achieved, taking into account the rheological properties, film-forming properties and application compatibility of the system. This significantly improves the overall performance of the leather isolation coating agent and meets the requirements of leather post-processing techniques such as embossing and softening.

[0026] As a preferred embodiment, the organic amine auxiliary is Dow AMP-95 or Solvay AN-130.

[0027] As a preferred embodiment, the leveling agent is an organosilicon leveling agent.

[0028] Secondly, the present invention provides a low-odor, environmentally friendly leather isolation coating agent prepared by the preparation method described in the first aspect.

[0029] Thirdly, the present invention provides an application of a coating agent prepared by the preparation method described in the first aspect in the field of leather finishing materials.

[0030] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: (1) The siloxane segments of the waterborne polycarbonate polyurethane of the present invention are chemically bonded into the molecular backbone, which can inhibit the migration and precipitation of small molecule silicone oil, eliminate the odor of silicone oil, and reduce the volatilization of free low molecular weight siloxanes; at the same time, the covalently grafted siloxane-phenyl segments migrate to the film surface through siloxane, while the polar polyurethane chains are enriched at the leather interface. The polar chains at the interface ensure adhesion and effectively improve the peel strength of the coating layer.

[0031] (2) After the waterborne alkyl silicone wax emulsion of the present invention is introduced into the leather isolation coating agent, the silicone wax component forms a dense hydrophobic isolation film between the raw leather and the upper coating resin. On the one hand, it physically inhibits the migration and accumulation of volatile odor molecules, easily photo-oxidized components, and free oils inside the raw leather to the coating interface; while the triethanolamine adjusts the weak alkalinity of the system, neutralizes volatile acidic substances, quenches photo-oxidized free radicals, and inhibits the rancidity of oils and the photochromic discoloration of phenolic substances, thereby simultaneously improving the leather odor level and resistance to photo-yellowing. On the other hand, the waterborne alkyl silicone wax emulsion can eliminate the weak interface layer caused by oil migration, improve the interface wetting and anchoring between the coating resin and the leather fibers, and enhance the peel strength of the coating layer.

[0032] (3) The compound thickener system of the present invention imparts suitable rheological properties to the coating agent, ensuring that the coating is uniform and complete in the embossing process, effectively isolating the direct contact between the high-temperature metal plate and the base coating, thereby significantly improving the wet peel strength of the finished product and reducing the risk of delamination; at the same time, the compound thickener itself does not contain photosensitive structures such as nitrate esters, and can reduce or eliminate the use of organic solvents, thereby weakening the photothermal yellowing inducing factors from the source of the formulation, and significantly improving the photochromic resistance of light-colored leather products; in addition, the compounding scheme greatly reduces the total amount of volatile solvents in the system, which significantly reduces the odor of the coating agent during the spraying and drying process, and improves the environmental friendliness of the operation. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0034] Figure 1 These are the FTIR images of ordinary waterborne polyurethane and waterborne polycarbonate polyurethane in Example 1 of the present invention.

[0035] Figure 2 A physical image of the coating agent used in Example 1.

[0036] Figure 3 Actual photos of the light yellowing test results for Example 1 and Comparative Example 1.

[0037] Figure 4 Actual images of the thermal viscosity test results for Example 1 and Comparative Example 1.

[0038] Figure 5 Actual images of the finished wet peel strength test results of Example 1 and Comparative Example 1.

[0039] Figure 6 Images of finished products from Example 1 and Comparative Example 1, showing their wet rub resistance test results. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] The sources of some components in the examples and comparative examples are as follows: Ordinary waterborne polyurethane, model SY-308, purchased from Haiyiyi New Material Technology Co., Ltd. Ordinary polycarbonate diol, model SYHP1000, purchased from Shanghai Shuyu Chemical Co., Ltd. 1,4-Butanediol, CAS No. 110-63-4, purchased from Sinopharm Chemical Reagent Co., Ltd. Dihydroxyl-terminated poly(dimethylsiloxane-co-diphenylsiloxane), model Y116226, was purchased from Shanghai Beyotime Biotechnology Co., Ltd. Dimethyl carbonate, CAS No. 616-38-6, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Isophorone diisocyanate, product number I109582, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Dimethylolpropionic acid, CAS No. 4767-03-7, was purchased from Sinopharm Chemical Reagent Co., Ltd. Dibutyltin dilaurate, CAS No. 77-58-7, purchased from Sinopharm Chemical Reagent Co., Ltd. Stannous octoate, CAS No. 301-10-0, purchased from Sinopharm Chemical Reagent Co., Ltd. Hydroxyethyl methacrylate, CAS No. 868-77-9, purchased from Sinopharm Chemical Reagent Co., Ltd. Triethylamine, CAS No. 121-44-8, was purchased from Sinopharm Chemical Reagent Co., Ltd. The silicone wax, model MY-2801, was purchased from Anhui Mingyi Silicon Industry Co., Ltd. Isotridecyl polyoxyethylene ether, CAS No. 9043-30-5, purchased from Sinopharm Chemical Reagent Co., Ltd. Span 60, CAS No. 1338-41-6, purchased from Sinopharm Chemical Reagent Co., Ltd. Triethanolamine, CAS No. 102-71-6, was purchased from Sinopharm Chemical Reagent Co., Ltd. Water-based acrylic thickener, purchased from Guangdong Nanhui New Materials Co., Ltd. Waterborne polyurethane thickener, purchased from Guangdong Nanhui New Materials Co., Ltd. Organic amine adjuvants: Dow AMP-95, Solvay AN-130; The silicone leveling agent, model BD-3410, was purchased from Hangzhou Baode New Material Technology Co., Ltd.

[0042] Example 1 This embodiment provides a method for preparing a low-odor, environmentally friendly leather insulating coating agent, including the following steps: S1. 80 parts of deionized water, 6 parts of waterborne silicone wax emulsion, and 20 parts of waterborne polycarbonate polyurethane were added to a dispersion vessel and stirred and dispersed at 400 r / min for 10 min to obtain a mixture. S2. Add 1 part of silicone leveling agent and 1 part of organic amine additive Dow AMP-95 to the mixture described in step S1. Stir and mix for 10 minutes at a speed of 600 r / min. Adjust the pH to 9. Then add 2 parts of thickener (1.5 parts of water-based acrylic thickener and 0.5 parts of water-based polyurethane thickener), mix well, and filter to obtain a low-odor environmentally friendly leather isolation coating agent.

[0043] Preparation of the waterborne polycarbonate polyurethane: 300 parts by weight of 1,4-butanediol and 50 parts by weight of dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane) were added to a reaction vessel, followed by 0.08 parts by weight of tetrabutyl titanate. The mixture was heated to 150°C and then 420 parts by weight of dimethyl carbonate were added. The reaction was carried out at 170°C and a vacuum of 200 Pa for 2 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain modified polycarbonate diol. 50 parts by weight of the modified polycarbonate diol and 30 parts by weight of isophorone diisocyanate were then added to the reaction vessel. Cyanate ester was added to a reactor and prepolymerized at 75°C for 60 min. After cooling to 45°C, 2 parts of acetone were added to adjust the viscosity. Then, 3 parts of dimethylolpropionic acid, 5 parts of 1,4-butanediol, 0.2 parts of dibutyltin dilaurate, and 0.2 parts of stannous octoate were added and reacted at 55°C for 4 h. 2 parts of hydroxyethyl methacrylate were added and reacted for 120 min. 2 parts of triethylamine were added for neutralization reaction for 30 min. Finally, 100 parts of deionized water were added and emulsified for 50 min. The mixture was then rotary evaporated to obtain waterborne polycarbonate polyurethane.

[0044] Preparation of the aqueous silicone wax emulsion: By weight, 30 parts of organosilicone wax, 2 parts of isotridecyl alcohol polyoxyethylene ether, 2 parts of Span 60 and 4 parts of triethanolamine were added to a reaction vessel, heated to 85°C and stirred for 50 min, then 100 parts of hot water at 80°C were added, and stirred at 100 r / min for 120 min. After cooling, the mixture was homogenized at 30 MPa for 10 min to obtain the aqueous silicone wax emulsion.

[0045] Example 2 This embodiment provides a method for preparing a low-odor, environmentally friendly leather insulating coating agent, including the following steps: S1. 70 parts of deionized water, 3 parts of waterborne silicone wax emulsion, and 10 parts of waterborne polycarbonate polyurethane were added to a dispersion vessel and stirred and dispersed at 200 r / min for 30 min to obtain a mixture. S2. Add 0.1 parts of silicone leveling agent and 0.1 parts of organic amine additive Solvay AN-130 to the mixture described in step S1, stir and mix at 400 r / min for 20 min, adjust the pH to 8, then add 1 part of thickener (0.5 parts of water-based acrylic thickener and 0.5 parts of water-based polyurethane thickener), mix well, filter, and obtain a low-odor environmentally friendly leather isolation coating agent.

[0046] Preparation of the waterborne polycarbonate polyurethane: 280 parts by weight of 1,4-butanediol and 40 parts by weight of dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane) were added to a reaction vessel, followed by 0.06 parts by weight of tetrabutyl titanate. The mixture was heated to 145°C, and then 400 parts by weight of dimethyl carbonate were added. The reaction was carried out at 165°C and a vacuum of 200 Pa for 4 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain modified polycarbonate diol. 40 parts by weight of modified polycarbonate diol and 20 parts by weight of isophorone diol were then added to the reaction vessel. Isocyanate was added to a reactor and prepolymerized at 70°C for 80 min. After cooling to 45°C, 1 part of acetone was added to adjust the viscosity. Then, 2 parts of dimethylolpropionic acid, 4 parts of 1,4-butanediol, 0.1 parts of dibutyltin dilaurate, and 0.1 parts of stannous octoate were added and reacted at 50°C for 6 h. 1 part of hydroxyethyl methacrylate was added and reacted for 100 min. 1 part of triethylamine was added for neutralization reaction for 20 min. Finally, 90 parts of deionized water were added and emulsified for 40 min. The mixture was then rotary evaporated to obtain waterborne polycarbonate polyurethane.

[0047] Preparation of the aqueous silicone wax emulsion: By weight, 20 parts of organosilicon wax, 1 part of isotridecyl alcohol polyoxyethylene ether, 1 part of Span 60 and 2 parts of triethanolamine were added to a reaction vessel, heated to 75°C and stirred for 60 min, then 90 parts of hot water at 80°C were added, and stirred at 80 r / min for 120 min. After cooling, the mixture was homogenized at 20 MPa for 10 min to obtain the aqueous silicone wax emulsion.

[0048] Example 3 This embodiment provides a method for preparing a low-odor, environmentally friendly leather insulating coating agent, including the following steps: S1. 75 parts of deionized water, 4 parts of waterborne silicone wax emulsion, and 16 parts of waterborne polycarbonate polyurethane were added to a dispersion vessel and stirred and dispersed at 300 r / min for 20 min to obtain a mixture. S2. Add 0.5 parts of silicone leveling agent and 0.4 parts of organic amine additive Solvay AN-130 to the mixture described in step S1. Stir and mix at 500 r / min for 16 min, adjust the pH to 8.4, then add 1.5 parts of thickener (1.0 part of water-based acrylic thickener and 0.5 parts of water-based polyurethane thickener), mix well, and filter to obtain a low-odor environmentally friendly leather isolation coating agent.

[0049] Preparation of the waterborne polycarbonate polyurethane: 290 parts by weight of 1,4-butanediol and 45 parts by weight of dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane) were added to a reaction vessel, followed by 0.07 parts by weight of tetrabutyl titanate. The mixture was heated to 146°C, and then 410 parts by weight of dimethyl carbonate were added. The reaction was carried out at 168°C and a vacuum of 200 Pa for 3 hours. After the reaction was completed, the mixture was distilled under reduced pressure to obtain modified polycarbonate diol. 44 parts by weight of the modified polycarbonate diol and 26 parts by weight of isophorone diisocyanate were added to… The mixture was placed in a reactor and prepolymerized at 72°C for 70 min. After cooling to 45°C, 1.4 parts of acetone were added to adjust the viscosity. Then, 2.6 parts of dimethylolpropionic acid, 4.5 parts of 1,4-butanediol, 0.15 parts of dibutyltin dilaurate, and 0.14 parts of stannous octoate were added and reacted at 52°C for 5 h. 1.8 parts of hydroxyethyl methacrylate were added and reacted for 110 min. 1.4 parts of triethylamine were added for neutralization reaction for 25 min. Finally, 96 parts of deionized water were added and emulsified for 44 min. The mixture was then rotary evaporated to obtain waterborne polycarbonate polyurethane.

[0050] Preparation of the aqueous silicone wax emulsion: 24 parts by weight of organosilicon wax, 1.5 parts by weight of isotridecyl alcohol polyoxyethylene ether, 1.7 parts by weight of Span 60 and 3 parts by weight of triethanolamine were added to a reaction vessel, heated to 78°C and stirred for 54 min, then 95 parts by weight of hot water at 80°C were added and stirred at 90 r / min for 80 min. After cooling, the mixture was homogenized at 24 MPa for 8 min to obtain the aqueous silicone wax emulsion.

[0051] Comparative Example 1 The difference between this comparative example and Example 1 is that ordinary waterborne polyurethane (model SY-308) was used instead of waterborne polycarbonate polyurethane.

[0052] Comparative Example 2 The difference between this comparative example and Example 1 is that ordinary polycarbonate diol (model SYHP1000) was used instead of modified polycarbonate diol in the preparation of waterborne polycarbonate polyurethane.

[0053] Comparative Example 3 The difference between this comparative example and Example 1 is that water-based silicone wax emulsion is not added in step S1.

[0054] Comparative Example 4 The difference between this comparative example and Example 1 is that the thickener was changed to 2 parts of water-based acrylic thickener.

[0055] Comparative Example 5 The difference between this comparative example and Example 1 is that the thickener was changed to 2 parts of water-based polyurethane thickener.

[0056] Comparative Example 6 The difference between this comparative example and Example 1 is that the thickener was changed to 1.8 parts of water-based acrylic thickener and 0.2 parts of water-based polyurethane thickener.

[0057] Comparative Example 7 The difference between this comparative example and Example 1 is that the thickener was changed to 0.5 parts of water-based acrylic thickener and 1.5 parts of water-based polyurethane thickener.

[0058] Performance testing: After the sofa leather blanks were roller-patched and pre-treated with buffing, the bottom of the roller was coated once, and the finishing agents of the examples and comparative examples were sprayed on respectively. Embossing was performed (through embossing machine, small lychee pattern, 140℃, 180kg pressure). The leather blanks were tumbled for 12 hours until the pattern was full and the leather blanks were soft and bubbly. After spraying the top coat, the adhesion of the adhesive tape was tested. The varnish was sprayed twice more. After conventional drying and standing for 24 hours, the performance test results are shown in Tables 1 and 2.

[0059] Table 1 Table 2 This invention first prepares a modified polycarbonate diol by mixing 1,4-butanediol, dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane), and dimethyl carbonate. Then, a waterborne polycarbonate polyurethane is synthesized by using the modified polycarbonate diol and isophorone diisocyanate as raw materials. Next, an aqueous silicone wax, isotretinoin polyoxyethylene ether, Span 60, triethanolamine, and hot water are mixed and emulsified to obtain an aqueous silicone wax emulsion. Finally, a coating agent (Examples 1-3) is prepared using the aqueous polycarbonate polyurethane, the aqueous silicone wax emulsion, a thickener, an organic amine additive, a leveling agent, and deionized water as raw materials, exhibiting superior overall performance.

[0060] Compared to Example 1, using ordinary waterborne polyurethane (model SY-308) instead of waterborne polycarbonate polyurethane resulted in a decrease in odor level and peel strength due to the lack of the effect of waterborne polycarbonate polyurethane (Comparative Example 1); compared to Example 1, using ordinary polycarbonate diol (model SYHP1000) instead of modified polycarbonate diol in the preparation of waterborne polycarbonate polyurethane resulted in a decrease in odor level and peel strength due to the lack of the effect of modified polycarbonate diol (Comparative Example 2); compared to Example 1, not adding waterborne silicone wax emulsion in step S1 resulted in a decrease in odor level, poorer light yellowing resistance, and reduced peel strength due to the lack of the effect of waterborne silicone wax emulsion (Comparative Example 3); compared to Example 1, replacing the thickener with 2 parts of waterborne acrylic thickener resulted in a decrease in odor level due to the lack of polyurethane thickener compounding. Comparative Example 4: Compared to Example 1, the thickener was changed to 2 parts of waterborne polyurethane thickener. The lack of waterborne acrylic thickener resulted in a decrease in odor level, poorer light yellowing resistance, and reduced peel strength. Comparative Example 5: Compared to Example 1, the thickener was changed to 1.8 parts of waterborne acrylic thickener and 0.2 parts of waterborne polyurethane thickener. Excessive use of waterborne acrylic thickener led to poor results, resulting in a decrease in odor level, poorer light yellowing resistance, and reduced peel strength. Comparative Example 6: Compared to Example 1, the thickener was changed to 0.5 parts of waterborne acrylic thickener and 1.5 parts of waterborne polyurethane thickener. Excessive use of waterborne polyurethane thickener led to poor results, resulting in a decrease in odor level, poorer light yellowing resistance, and reduced peel strength. Comparative Example 7:

Claims

1. A method for preparing a low-odor, environmentally friendly leather insulating coating agent, characterized in that, Includes the following steps: S1. Add deionized water, waterborne silicone wax emulsion, and waterborne polycarbonate polyurethane to a dispersion vessel and stir to disperse to obtain a mixture; S2. Add leveling agent and organic amine additive to the mixture described in step S1 and stir to mix. Adjust the pH to 8-9, then add thickener and mix well. Filter to obtain a low-odor environmentally friendly leather isolation coating agent. The method for preparing the waterborne polycarbonate polyurethane is as follows: 1,4-butanediol, dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane) and dimethyl carbonate are mixed to prepare a modified polycarbonate diol, and then the modified polycarbonate diol and isophorone diisocyanate are used as raw materials to carry out a synthesis reaction to obtain the waterborne polycarbonate polyurethane.

2. The method for preparing a low-odor, environmentally friendly leather insulating coating agent according to claim 1, characterized in that, The components, by weight, include: 10-20 parts waterborne polycarbonate polyurethane, 3-6 parts waterborne silicone wax emulsion, 1-2 parts thickener, 0.1-1 parts organic amine additive, 0.1-1 parts leveling agent, and 70-80 parts deionized water.

3. The method for preparing a low-odor, environmentally friendly leather insulating coating agent according to claim 1, characterized in that, The preparation steps of the modified polycarbonate diol are as follows: by weight, 280-300 parts of 1,4-butanediol and 40-50 parts of dihydroxy-terminated poly(dimethylsiloxane-co-diphenylsiloxane) are added to a reaction vessel, then 0.06-0.08 parts of tetrabutyl titanate are added, the temperature is raised to 145-150℃, and then 400-420 parts of dimethyl carbonate are added. The reaction is carried out at a temperature of 165-170℃ and a vacuum degree of 200Pa for 2-4 hours. After the reaction is completed, the modified polycarbonate diol is obtained by vacuum distillation.

4. The method for preparing a low-odor, environmentally friendly leather insulating coating agent according to claim 1, characterized in that, The synthesis reaction steps are as follows: 40-50 parts by weight of modified polycarbonate diol and 20-30 parts by weight of isophorone diisocyanate are added to a reactor and prepolymerized at 70-75°C for 60-80 minutes. After cooling to 45°C, 1-2 parts by weight of acetone are added to adjust the viscosity. Then, 2-3 parts by weight of dimethylolpropionic acid, 4-5 parts by weight of 1,4-butanediol, 0.1-0.2 parts by weight of dibutyltin dilaurate and 0.1-0.2 parts by weight of stannous octoate are added and reacted at 50-55°C for 4-6 hours. 1-2 parts by weight of hydroxyethyl methacrylate are added and reacted for 100-120 minutes. 1-2 parts by weight of triethylamine are added for neutralization reaction for 20-30 minutes. Finally, 90-100 parts by weight of deionized water are added for emulsification for 40-50 minutes, followed by rotary evaporation to obtain waterborne polycarbonate polyurethane.

5. The method for preparing a low-odor, environmentally friendly leather insulating coating agent according to claim 1, characterized in that, The method for preparing the aqueous silicone wax emulsion is as follows: organosilicone wax, isotretinoin polyoxyethylene ether, Span 60, triethanolamine, and hot water are mixed and then emulsified to obtain the aqueous silicone wax emulsion.

6. The method for preparing a low-odor, environmentally friendly leather insulating coating agent according to claim 5, characterized in that, The emulsification process is as follows: by weight, 20-30 parts of silicone wax, 1-2 parts of isotridecyl polyoxyethylene ether, 1-2 parts of Span 60 and 2-4 parts of triethanolamine are added to a reaction vessel, heated to 75-85°C and stirred for 50-60 minutes, then 90-100 parts of hot water at 80°C are added, and stirred at 80-100 r / min for 60-120 minutes. After cooling, the mixture is homogenized at 20-30 MPa for 5-10 minutes to obtain an aqueous silicone wax emulsion.

7. The method for preparing a low-odor, environmentally friendly leather insulating coating agent according to claim 1, characterized in that, The thickener is a water-based acrylic thickener and a water-based polyurethane thickener; The mass ratio of the water-based acrylic thickener to the water-based polyurethane thickener is (1~3):

1.

8. The method for preparing a low-odor, environmentally friendly leather insulating coating agent according to claim 1, characterized in that, The organic amine adjuvant is either Dow AMP-95 or Solvay AN-130.

9. A low-odor, environmentally friendly leather insulating coating agent, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the coating agent obtained by the preparation method according to any one of claims 1 to 8 in the field of leather finishing materials.

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