Waterborne polyurethane self-extinction gloss oil and preparation method thereof

Abstract

The invention discloses waterborne polyurethane self-extinction gloss oil and a preparation method thereof, and belongs to the technical field of waterborne polyurethane gloss oil. The waterborne polyurethane self-extinction gloss oil is prepared from the following raw material components: polymer polyol, a dihydroxyl organic silicon intermediate, isocyanate, micromolecular polyol, a carboxyl-containing dihydroxyl micromolecular alcohol chain extender, a micromolecular polyamine chain extender, an organic silicon modifier and an auxiliary agent, the preparation method mainly comprises the steps of prepolymerization reaction, hydrophilic chain extension, micromolecule amine post-chain extension, neutralization, emulsification and desolvation, and auxiliary agent blending and thickening. The glossiness of the prepared waterborne polyurethane self-extinction gloss oil is smaller than or equal to 1.2, the comprehensive performance of yellowing resistance, scratch resistance, friction resistance, solvent resistance, dry and wet rubbing and the like is outstanding, and the application requirement of the leather surface layer coating field for the self-extinction gloss oil can be met. The preparation method provided by the invention is mild in reaction condition and easy to control in operation, the particle size distribution of microscopic particles of the obtained product is uniform, and the stability of products in different batches is good.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water-based polyurethane gloss oil, and specifically discloses a water-based polyurethane matt gloss oil and a preparation method thereof. BACKGROUND

[0002] In recent years, with the improvement of the living standards of residents in China, people have higher and higher requirements for leather. Physical properties such as scratch resistance, friction resistance, smooth hand feeling and strong water resistance are excellent properties that leather should directly present during use at present and in the future. Therefore, higher requirements are put forward for the processing technology of leather. At present, in the surface treatment process in the fields of upper leather, luggage leather and sofa leather, a layer of water-based polyurethane gloss oil is usually sprayed to improve the performance and skin feeling of leather.

[0003] According to the glossiness of water-based polyurethane gloss oil after spraying, the gloss oil can be divided into bright gloss oil and matt gloss oil. In order to meet the needs of different aesthetic vision of people, matt gloss oil has become an indispensable product in the field of leather surface spraying. According to market research data, the consumption of matt gloss oil may be more than that of bright gloss oil.

[0004] Market demand promotes the research, production and promotion of matt gloss oil. However, the comprehensive performance of matt gloss oil such as scratch resistance, friction resistance, yellowing resistance, solvent resistance, dry and wet rubbing, stability and smooth hand feeling has always been the key application index of product demand side. So far, the preparation technology of matt gloss oil in China is still in the optimization and improvement stage and has not been fully mature, which leads to the current situation that the demand for matt gloss oil in China mainly depends on imports. There are very few relevant reports on matt gloss oil in the literature.

[0005] The only relevant reports are: CN111763472A discloses a semi-matt water-based polyurethane gloss oil with high folding resistance and wear resistance, and CN103726178B discloses a polyurethane matt gloss oil. However, the two inventions achieve the purpose of matt gloss by using super-high-hardness polypropylene matt wax or silicone matt powder. The matt wax or matt powder is easy to precipitate during application, which causes the surface of the sprayed leather to appear white and powder off, thereby affecting the further processing and use of the leather.

[0006] CN107722236B discloses a preparation method and application of a silicone-modified self-matting waterborne polyurethane for synthetic leather. According to the patent data reported therein, the glossiness of the self-matting waterborne polyurethane involved in this invention patent can be achieved to ≤0.5, with a significant matting effect. However, there are also problems with the process and formulation. Specifically, the prepolymerization process involves mixing amino silicone oil, polymer diol, diisocyanate, and triethylamine and then reacting them. At this time, the system is weakly alkaline, which will accelerate the polymerization process and cause uneven distribution of hard segments and soft satin on the molecular chain. Especially when there is a trace of water in the material, it may cause gelation. At the same time, the HDI trimer added after emulsification is unevenly dispersed and may even cause precipitation or gelation during storage or use, affecting the normal use of the product.

[0007] CN112851898A discloses a self-matting waterborne polyurethane resin, a preparation method, and an application. The product, preparation method, and application involved in this invention belong to the field of self-matting resins and do not have the characteristics of varnish, such as a smooth feel. At the same time, this invention uses polyhydroxy diamine to achieve cross-linking with an isocyanate curing agent, and the molecular chain will have a high content of side chain hydroxyl groups, which will result in the maximum hardness of the product being lower than that of conventional products. At the same time, the limited source of raw materials for polyhydroxy diamine will also limit the promotion and use of this invention method.

[0008] Patent CN102733198B discloses a water-based polyurethane varnish and its preparation process, which prepares a bright-gloss water-based polyurethane. Polycarbonate diol is used in the raw material components of the invention, but the price of this material is relatively high, and the prepared resin is relatively hard and lacks flexibility.

[0009] Based on the above problems, in order to make domestically produced matting varnish occupy more market share, it is urgent to develop a water-based polyurethane self-matting varnish and its preparation method whose comprehensive performance can meet application requirements. Summary of the Invention

[0010] In light of this, the present invention aims to provide a water-based polyurethane self-matting varnish and a method for its preparation. The prepared water-based polyurethane self-matting varnish exhibits a gloss of ≤1.2 and exhibits outstanding comprehensive properties, including yellowing resistance, scratch resistance, friction resistance, solvent resistance, and wet and dry rubbing resistance, meeting the application requirements for self-matting varnishes in the leather surface finishing field. The preparation method provided by the present invention features mild reaction conditions, easy-to-control operation, and a uniform particle size distribution of the resulting microparticles, with excellent product stability across batches.

[0011] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A water-based polyurethane self-matting varnish, the raw materials of which are respectively as follows in parts by weight: 15-50 parts of polymer polyol, 2-15 parts of dihydroxy silicone intermediate, 15-40 parts of isocyanate, 0.1-3 parts of small molecule polyol, 0.1-2 parts of carboxyl-containing dihydroxy small molecule alcohol chain extender, 1-10 parts of small molecule polyamine chain extender, 0.1-15 parts of silicone modifier, and 0.1-10 parts of auxiliary agent.

[0012] The polymer polyol is one of polyester polyol and polyether polyol; Wherein, the polyester polyol is one or more of adipic acid polyester polyol, succinic acid polyester polyol, glutaric acid polyester polyol, and sebacic acid polyester polyol; The polyether polyol is one of polyoxypropylene polyol, polytetramethylene glycol and copolyether polyol thereof, and polyoxyethylene polyol; The dihydroxy silicone intermediate is dihydroxy-terminated polydimethylsiloxane and its modified derivatives, with a molecular weight between 1000 and 10000; The isocyanate is one or more of isophorone diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate; The small molecule polyols include but are not limited to one or two of 1,3-propylene glycol, ethylene glycol, diethylene glycol, trimethylolpropane, 1,6-hexanediol, trimethylolpropane, and pentaerythritol; The carboxyl-containing dihydroxy small molecule alcohol chain extender includes but is not limited to 2,2-dihydroxymethyl propionic acid or 2,2-dihydroxymethyl butyric acid; The small molecule polyamine chain extender is a mixture of sodium sulfamate solution and polyamines, wherein the sodium sulfamate plays the role of chain extension and hydrophilicity, and the other polyamines play the role of chain extension, and the mass ratio of the two is 1: (1-10).

[0013] The sodium sulfamate solution is preferably sodium ethylenediamine sulfonate, and also includes sodium sulfonate salts of other diamine derivatives; the polyamine is one or more of hydrazine hydrate, ethylenediamine, diethylenetriamine, hexamethylenediamine and isophoronediamine; The organosilicon modifier is one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, N-cyclohexyl-3-aminopropylmethyldimethoxysilane and 3-diethylenetriaminopropyltrimethoxysilane; The auxiliary agent is a thickening agent, a hand feel agent, a wetting agent, and a defoaming agent, all of which are commercially available products, the thickening agent can be a non-ionic associated thickening agent, the hand feel agent can be a product compounded by silicone and wax, the wetting agent can be a polyoxyethylene ether surfactant, and the defoaming agent can be a polydimethylsiloxane; the mass ratio of the thickening agent, the hand feel agent, the wetting agent, and the defoaming agent is 50-100: 50-100: 1-5: 1-5.

[0014] Preferably, an aqueous polyurethane self-matt gloss oil is prepared from the following raw materials in parts by weight: 20-40 parts of a polymer polyol, 3-15 parts of a dihydroxy silicone intermediate, 20-30 parts of isocyanate, 1-2 parts of a small molecule polyol, 0.5-1 part of a carboxyl-containing dihydroxy small molecule alcohol chain extender, 2-8 parts of a small molecule polyamine chain extender, 2-10 parts of a silicone modifier, and 0.5-5 parts of an auxiliary agent.

[0015] Further, the present application provides a preparation method of the aqueous polyurethane self-matt gloss oil, and the specific steps are as follows: (1) After dehydration of the polymer polyol and the dihydroxy silicone intermediate, the isocyanate and the small molecule polyol are simultaneously pre-polymerized, and then the pre-polymer is sequentially subjected to hydrophilic chain extension, small molecule amine chain extension, and neutralization to obtain a pre-polymer; (2) The pre-polymer obtained in step (1) is slowly added to desalted water under high-speed dispersion, and then an aqueous solution of the silicone modifier is immediately added for emulsification after the addition is completed; (3) After the emulsification is completed, the aqueous polyurethane self-matt gloss oil is obtained through desolventization, auxiliary agent blending, and thickening.

[0016] Further, the pre-polymerization process in step (1) is specifically as follows: The polymer polyol and the dihydroxy silicone intermediate are dehydrated at 120°C and a negative pressure of ≤-0.095 MPa, and then cooled to below 90°C, while the isocyanate and the small molecule polyol are reacted at 50°C-90°C for 1h-3h.

[0017] Preferably, the dehydrated polymer polyol and dihydroxy silicone intermediate are cooled to below 85°C, while the isocyanate and the small molecule polyol are reacted at 60°C-85°C for 1.5h-3h.

[0018] Further, the hydrophilic chain extension process in step (1) is specifically as follows: After the pre-polymerization is completed by sampling the reaction solution and titration detection of the residual mass fraction of NCO (isocyanate group) reaching 9-12%, the carboxyl-containing dihydroxy small molecule alcohol chain extender and the catalyst are added, and reacted at 50°C-90°C for 2h-6h until the residual mass fraction of NCO is 5-7%, reaching the qualified standard. Preferably, after the prepolymerization is completed by detecting that the residual NCO mass fraction reaches 9-12%, a carboxyl-containing dihydroxy small molecule alcohol chain extender and a catalyst are added, and the reaction is carried out at 60°C-90°C for 2h-5h until the residual NCO mass fraction reaches 5-7%, which is qualified.

[0019] The catalyst is organic tin or organic bismuth, and the amount used is 0.5‰-5‰ of the mass of the polymer polyol.

[0020] Furthermore, the process of chain extension of the small molecule amine in step (1) is specifically as follows: The product obtained after hydrophilic chain extension is cooled to below 60°C, acetone is added at a ratio of 50-100% of the mass fraction of the prepolymer, and after dilution, a small molecule polyamine chain extender is slowly added dropwise at 20°C-50°C; Preferably, the product obtained after hydrophilic chain extension is cooled to below 55° C., diluted with solvent, and then a small molecule polyamine chain extender is slowly added dropwise at 20° C.-45° C.

[0021] Furthermore, the neutralizing agent used in the neutralization operation in step (1) is triethylamine, and the degree of neutralization is 90%-115%; the neutralization temperature is 10°C-50°C, and the time is 5-30 minutes.

[0022] Furthermore, the process of slowly adding desalted water to the prepolymer obtained in step (1) under high-speed dispersion for emulsification in step (2) is specifically as follows: Under stirring at 1000-5000 r / min, the temperature is controlled at 0°C-50°C, and desalted water is slowly added to the prepolymer obtained in step (1). The addition time of the desalted water is 2-3 hours, and the solid content of the prepolymer is finally made into 25-35%, and the rest is desalted water. The stirring speed is adjusted in time according to the change of the viscosity of the system. The higher the viscosity, the higher the stirring speed is adjusted. After the addition of the desalted water, an aqueous solution miscible with the organosilicon modifier and the desalted water is immediately added. The mass ratio of the organosilicon modifier to the desalted water is 1:20-100. After the addition, the mixture is stirred for 5-20 minutes to complete the emulsification process.

[0023] Preferably, under stirring at 1000-2000 r / min, the temperature is controlled at 0°C-40°C, and desalted water is slowly added to the reaction product obtained in step (1). The solid content of the prepolymer is preferably 25-30%, and the stirring speed is timely adjusted according to the change of the viscosity of the system. The speed is adjusted to 3000-4000 r / min as the viscosity increases. When the viscosity increases and decreases suddenly, it is considered that the phase inversion is completed. The speed is adjusted to 1000-2000 r / min. After the water is added, an aqueous solution miscible with the organosilicon modifier and the desalted water is immediately added. The mass ratio of the organosilicon modifier to the desalted water is 1:50. The whole process is controlled for 15-90 minutes. After the addition is completed, stirring is carried out for 10-30 minutes to complete the emulsification process.

[0024] Furthermore, the desolventizing operation conditions in step (3) are negative pressure ≤ -0.095 MPa and temperature 20°C-50°C.

[0025] Compared with the prior art, the technology of the present invention has the following beneficial effects: (1) The present invention uses waterborne polyurethane self-matting technology to replace the traditional matting powder or matting wax to achieve the purpose of matting, which belongs to the field of complete self-matting. The present invention controls the resin particle size by adjusting the raw material formula and process, that is, controlling the addition ratio of the hydrophilic agent so that the resin dissolves in water while the particle size is controlled at 1-100 μm, thereby achieving self-matting and avoiding the problems of matting powder or matting wax easily precipitating during application, resulting in whitening and powdering of the leather surface after spraying; (2) The present invention improves the hand feel by embedding a dihydroxy silicone intermediate into the molecular chain of waterborne polyurethane, thus avoiding the incompatibility and other problems that may be caused by directly adding a hand feel agent; (3) The present invention firstly makes the product have a certain molecular weight through prepolymerization, but controls the viscosity within an appropriate range to achieve the basic resin performance, then makes the resin soluble in water through hydrophilic chain extension, and prepares the key amine of water-based products, and then improves the cross-linking degree of the resin through small molecule amine chain extension, which plays a key role in the toughness, hardness and other properties of the product. Further, after emulsification, the organosilicon modifier is embedded in the molecular structure of the product through reaction, and cross-linking is achieved, thereby enhancing the water resistance, tensile strength, anti-adhesion and other physical properties of the product; (4) The preparation method of the present invention has mild reaction conditions and easy operation control. The particle size distribution of the obtained microscopic particles is uniform, and the product stability between different batches is good. (5) The product prepared by the present invention has a glossiness of ≤1.2, and has outstanding comprehensive properties such as yellowing resistance, scratch resistance, friction resistance, solvent resistance, and dry and wet rubbing resistance, and can meet the demand for self-matting varnish in the field of leather surface finishing. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0027] The present invention has no particular limitation on the source of the polymer polyol, and any commercially available product or homemade product known to those skilled in the art may be used. There is no particular limitation on the source of the isocyanate, and any commercially available product known to those skilled in the art may be used.

[0028] In order to further illustrate the present invention, the following examples are provided for detailed description. The raw materials used in the following examples of the present invention are all commercially available.

[0029] Example 1 A water-based polyurethane self-matting varnish and its preparation method A water-based polyurethane self-matting varnish, the raw material components and weight parts of which are shown in Table 1.

[0030] Table 1 Raw material components and weight parts of Example 1

[0031] The preparation method is as follows: (1) 60g of polytetramethylene ether glycol 2000 (PTMEG2000) and 5g of double-terminated hydroxyl polydimethylsiloxane (molecular weight 2000) were added to a 500mL reaction bottle and dehydrated at 110℃ and -0.098MPa for 90min. After dehydration, the temperature was lowered to below 85℃ and the vacuum was broken. 22g of isophorone diisocyanate and 0.6g of ethylene glycol were added and the reaction was continued at 85℃ for 2h. The reaction solution was sampled and titrated to detect the residual NCO mass fraction, which reached 9-12%. After the prepolymerization was completed, small molecule chain extenders 2,2 -0.8 g of dihydroxymethylpropionic acid, and 2 drops of dibutyltin dilaurate catalyst are added dropwise, and the reaction is carried out at 75°C for 3 hours until the residual mass fraction of NCO is 5-7%, which meets the requirements; after cooling to 55°C, 140 g of acetone is slowly added, and after dilution, an aqueous solution of 0.9 g of sodium ethylenediamine sulfonate, 5.2 g of isophorone diamine and 13 g of desalted water is slowly added dropwise under stirring, while paying attention to controlling the temperature at 30°C-40°C. After the addition is completed, 0.6 g of triethylamine is added dropwise at a temperature of 30°C-40°C for neutralization, and the addition time is 10 minutes to obtain a reaction product.

[0032] (2) With the disperser stirring at 1200 r / min and the temperature controlled at about 30°C, 180 g of desalted water was slowly added to the reaction product obtained in step (1) for emulsification. According to the change in the viscosity of the system, the stirring speed was adjusted to 1800 r / min in time. Water was added in about 50 minutes. After the water was added, 25 g of a 5% aqueous solution of γ-aminopropyltrimethoxysilane was immediately added. After the addition was completed in 5 minutes, stirring was continued for 10 minutes to complete the emulsification.

[0033] (3) After emulsification is completed, acetone is distilled under reduced pressure, and 3.2 g of additives such as thickeners are added under stirring to obtain water-based polyurethane self-matting varnish.

[0034] Example 2 A water-based polyurethane self-matting varnish and its preparation method A water-based polyurethane self-matting varnish, the raw material components and weight parts of which are shown in Table 2.

[0035] Table 2 Raw material components and weight parts of Example 2

[0036] The preparation method is as follows: (1) 60g of polytetramethylene ether glycol 1000 (PTMEG1000) and 3g of double-terminated hydroxyl polydimethylsiloxane (molecular weight 1000) were added to a 500mL reaction bottle and dehydrated at 110℃ and -0.098MPa for 90min. After dehydration, the temperature was lowered to below 85℃ and the vacuum was broken. 12g of isophorone diisocyanate, 18g of dicyclohexylmethane diisocyanate, and 0.8g of 1,4-Butanediol, react at 75°C for 3h; by sampling the reaction liquid, titrating and detecting the residual NCO mass fraction to reach 9-12%, it is judged that the prepolymerization is completed, and then 1.3g of small molecule chain extender 2,2-dihydroxymethylpropionic acid is added, and 2 drops of dibutyltin dilaurate catalyst are added dropwise, and the reaction is carried out at 70°C for 5h until the residual NCO mass fraction is 5-7%, which is qualified; after cooling to 55°C, 140g of acetone is slowly added, and after dilution, 0.7g of sodium ethylenediamine sulfonate, 1g of hydrazine hydrate, 1.6g of isophorone diamine and 8g of desalted water are slowly added dropwise under stirring, and the temperature is controlled at 20°C-30°C. After the addition is completed, 0.98g of triethylamine is added dropwise at a temperature of 20°C-30°C for neutralization, and the addition time is 12min to obtain a reaction product.

[0037] (2) With the disperser stirring at 1000 r / min and the temperature controlled at about 25°C, 180 g of desalted water was slowly added to the reaction product obtained in step (1) for emulsification. According to the change in the viscosity of the system, the stirring speed was adjusted to 1600 r / min in time. Water was added in about 35 minutes. After the water was added, 36 g of a 5% aqueous solution of N-cyclohexyl-3-aminopropylmethyldimethoxysilane was immediately added. After the addition was completed in 5 minutes, stirring was continued for 15 minutes to complete the emulsification.

[0038] (3) After emulsification is completed, acetone is distilled under reduced pressure, and 4.6 g of additives such as thickeners are added under stirring to obtain water-based polyurethane self-matting varnish.

[0039] Example 3 A water-based polyurethane self-matting varnish and its preparation method A water-based polyurethane self-matting varnish, the raw material components and weight parts of which are shown in Table 3.

[0040] Table 3 Raw material components and weight parts of Example 3

[0041] The preparation method is as follows: (1) 500 mL reaction bottle, 60 g polycarbonate diol 2000 (PCD2000), 6 g both end hydroxyl ethoxy modified polysiloxane (molecular weight 1350), 110 ℃, -0.098 MPa, dehydrated for 90 min; after dehydration, the temperature was reduced to below 75 ℃, vacuum was broken, 28 g isophorone diisocyanate, 3 g hexamethylene diisocyanate, 1.8 g neopentyl glycol was added, 80 ℃ reaction for 3 h; through sampling reaction liquid, titration detection NCO residual mass fraction reached 9-12% to judge the pre-polymerization was completed, then 1.6 g of small molecule chain extender 2,2-dimethylol propionic acid was added, and 2 drops of dibutyl tin dilaurate catalyst was added, 70 ℃ reaction for 5 h, until the NCO residual mass fraction was 5-7%, reached qualified; after cooling to 55 ℃, slowly add 140 g of acetone, after dilution, slowly add 0.5 g of ethylenediamine sodium sulfonate, 2.8 g of ethylenediamine and 6 g of desalted water miscible aqueous solution under stirring, while paying attention to temperature control 15 ℃-25 ℃, after the completion of dropwise addition, the temperature was controlled at 15 ℃-25 ℃, and 1.2 g of triethylamine was added for neutralization, the dropwise addition time was 20 min, and the reaction product was obtained.

[0042] (2) Under the stirring of the dispersion machine 1000 r / min, the temperature was controlled at about 15 ℃, and 210 g of desalted water was slowly added to the reaction product obtained in step (1) for emulsification. According to the change of the viscosity of the system, the stirring speed was adjusted to 1500 r / min in time, and the water was added for about 60 min. After the completion of water addition, 20 g of 5% γ-aminopropyl methyldiethoxysilane aqueous solution was immediately added, and the stirring was continued for 20 min after the addition was completed. Emulsification was completed.

[0043] (3) After emulsification, the acetone was distilled under reduced pressure, and 6 g of thickening agent and other auxiliaries were added under stirring to obtain a water-based polyurethane self-extinction gloss oil.

[0044] Example 4: A water-based polyurethane self-extinction gloss oil and a preparation method thereof A water-based polyurethane self-extinction gloss oil, the raw material components and weight fractions are shown in Table 4.

[0045] Table 4: Raw material components and weight fractions of Example 4

[0046] The preparation method is as follows: (1) 60g of polybutylene adipate diol 2000 (PBA2000) and 6g of double-terminal hydroxyl polyether modified polysiloxane (molecular weight 3000) were added to a 500mL reaction bottle and dehydrated at 110℃ and -0.098MPa for 90min. After dehydration, the temperature was lowered to below 75℃ and vacuum was broken. 27g of dicyclohexylmethane diisocyanate, 2g of hexamethylene diisocyanate, and 0.8g of Trimethylolpropane, react at 75°C for 3h; by sampling the reaction liquid, titrating and detecting the NCO residual mass fraction to reach 9-12%, it is judged that the prepolymerization is completed, and then 1g of small molecule chain extender 2,2-dihydroxymethylpropionic acid is added, and 2 drops of dibutyltin dilaurate catalyst are added dropwise, and the reaction is carried out at 65°C for 5h, until the NCO residual mass fraction is 5-7%, which meets the requirements; after cooling to 55°C, 140g of acetone is slowly added, and after dilution, 0.8g of sodium ethylenediamine sulfonate, 2.3g of hydrazine hydrate and 6g of desalted water are slowly added dropwise under stirring, and the temperature is controlled at 20°C-25°C. After the addition is completed, 0.96g of triethylamine is added dropwise at a temperature controlled at 20°C-25°C for neutralization, and the addition time is 16min to obtain a reaction product.

[0047] (2) With the disperser stirring at 1500 r / min and the temperature controlled at about 20°C, 200 g of desalted water was slowly added to the reaction product obtained in step (1) for emulsification. According to the change in the viscosity of the system, the stirring speed was adjusted to 2000 r / min in time. Water was added in about 75 minutes. After the water was added, 36 g of a 5% aqueous solution of N-(n-butyl)-3-aminopropyltrimethoxysilane was immediately added. After the addition was completed within 5 minutes, stirring was continued for 10 minutes to complete the emulsification.

[0048] (3) After emulsification is completed, acetone is distilled under reduced pressure, and 5.2 g of additives such as thickeners are added under stirring to obtain a water-based polyurethane self-matting varnish.

[0049] Performance Testing Glossiness: gloss meter detection.

[0050] Stability: The emulsion was stored in a drying room at 50°C for 14 consecutive days for evaluation.

[0051] Tensile strength and elongation: QB / T 2415-1998.

[0052] Water resistance: After soaking in water for 24 hours, compare and observe whether the film turns white before and after soaking. Whitening indicates poor water resistance.

[0053] Yellowing resistance: Keep the film at 120℃ for 4 hours and observe whether it turns yellow obviously.

[0054] Feel: Industry experience, the feeling of touch.

[0055] Dry rub resistance: place the leather sample on the rubbing table, adjust the rubbing head to be parallel to the surface of the leather sample, cover the standard rubbing cloth, set the parameters such as rubbing times, pressure and speed, start the instrument to conduct the rubbing test. After the test is completed, remove the rubbing cloth, observe the color change and grade with the gray card (GB / T 250-2008).

[0056] Wet rub resistance: prepare the wet rubbing cloth, squeeze off the excess water after soaking it completely. Cover the wet rubbing cloth on the rubbing head, set the parameters such as rubbing times, pressure and speed, start the instrument to conduct the rubbing test. After the test is completed, dry the rubbing cloth in the air, and grade with the gray card (GB / T 250-2008).

[0057] The comparative example is a commercially available product, a water-based matte finish, model DYU-1601, purchased from Zhejiang Daoyi Chemical Co., Ltd.

[0058] Table 5 Product performance test results of each example and comparative example

[0059] As can be seen from the product performance test results of each example and comparative example in Table 5, the water-based polyurethane self-extinguishing gloss oil product prepared in the embodiments of the present application has a glossiness of ≤1.2, and the properties of yellowing resistance, scratch resistance, rubbing resistance, solvent resistance, dry and wet rubbing resistance are all better than those of the comparative example product, which can meet the demand for self-extinguishing gloss oil in the field of leather surface finishing.

[0060] The specific embodiments of the present application are described above, it should be understood that the present application is not limited to the above specific embodiments, and those skilled in the art can make various modifications or changes within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. A water-based polyurethane self-matting varnish, characterized in that: The raw material composition is calculated by weight: 15-50 parts of polymer polyol, 2-15 parts of dihydroxy silicone intermediate, 15-40 parts of isocyanate, 0.1-3 parts of small molecule polyol, 0.1-2 parts of carboxyl-containing dihydroxy small molecule alcohol chain extender, 1-10 parts of small molecule polyamine chain extender, 0.1-15 parts of silicone modifier, and 0.1-10 parts of auxiliary agent.

2. The water-based polyurethane self-matting varnish according to claim 1, characterized in that: The polymer polyol is one of polyester polyol and polyether polyol; wherein the polyester polyol is one or more of adipic acid polyester polyol, succinic acid polyester polyol, glutaric acid polyester polyol and sebacic acid polyester polyol; the polyether polyol is one of polyoxypropylene polyol, polytetrahydrofuran and its copolyether polyol and polyoxyethylene polyol.

3. The water-based polyurethane self-matting varnish according to claim 1, characterized in that: The dihydroxy silicone intermediate is a double-terminated hydroxyl polydimethylsiloxane and its modified derivatives, with a molecular weight of 1000-10000; the isocyanate is one or more of isophorone diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate; the small molecule polyol includes but is not limited to one or two of 1,3-propylene glycol, ethylene glycol, diethylene glycol, trimethylolpropane, 1,6-hexanediol, trimethylolpropane and pentaerythritol.

4. The water-based polyurethane self-matting varnish according to claim 1, characterized in that: The carboxyl-containing dihydroxy small molecule alcohol chain extender includes but is not limited to 2,2-dihydroxymethylpropionic acid or 2,2-dihydroxymethylbutanoic acid; the small molecule polyamine chain extender is a mixture of sodium aminosulfonate solution and polyamine, and the mass ratio of the two is 1: (1-10).

5. The water-based polyurethane self-matting varnish according to claim 4, characterized in that: The sodium sulfamate is sodium ethylenediamine sulfonate or sodium sulfonate of other diamine derivatives; the polyamine is one or more of hydrazine hydrate, ethylenediamine, diethylenetriamine, hexamethylenediamine and isophoronediamine.

6. The water-based polyurethane self-matting varnish according to claim 1, characterized in that: The organosilicon modifier is one or more of γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-aminoethyl-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, N-cyclohexyl-3-aminopropylmethyldimethoxysilane and 3-diethylenetriaminopropyltrimethoxysilane; the auxiliary agent is one or more of a thickener, a feel agent, a wetting agent and a defoaming agent.

7. The water-based polyurethane self-matting varnish according to claim 6, characterized in that: The thickener is selected from nonionic associative thickeners, the hand feeling agent is selected from a composite product of silicone and wax, the wetting agent is selected from polyoxyethylene ether surfactants, and the defoaming agent is selected from polydimethylsiloxanes; the mass ratio of the thickener, hand feeling agent, wetting agent, and defoaming agent is 50-100:50-100:1-5:1-5.

8. The water-based polyurethane self-matting varnish according to claim 1, characterized in that: The raw material composition is calculated as follows by weight: 20-40 parts of polymer polyol, 3-15 parts of dihydroxy silicone intermediate, 20-30 parts of isocyanate, 1-2 parts of small molecule polyol, 0.5-1 part of carboxyl-containing dihydroxy small molecule alcohol chain extender, 2-8 parts of small molecule polyamine chain extender, 2-10 parts of silicone modifier, and 0.5-5 parts of auxiliary agent.

9. A method for preparing a waterborne polyurethane self-matting varnish, characterized in that: The specific steps are as follows: (1) After dehydration, the polymer polyol and dihydroxy silicone intermediate are prepolymerized with isocyanate and small molecule polyol, and then subjected to hydrophilic chain extension, small molecule amine chain extension and neutralization in sequence to obtain a prepolymer; (2) slowly adding desalted water to the prepolymer obtained in step (1) under high-speed dispersion, and immediately adding an aqueous solution of an organosilicon modifier to emulsify the prepolymer; (3) After emulsification, desolventization, additive preparation and thickening are carried out to obtain water-based polyurethane self-matting varnish; The specific process of prepolymerization in step (1) is as follows: Dehydrate the polymer polyol and dihydroxy silicone intermediate at 120°C and negative pressure ≤-0.095MPa, then cool to below 90°C, and simultaneously add isocyanate and small molecule polyol to react at 50°C-90°C for 1h-3h; The process of hydrophilic chain extension in step (1) is specifically as follows: After the prepolymerization is completed by sampling the reaction liquid and titrating to detect the residual NCO mass fraction reaching 9-12%, a carboxyl-containing dihydroxy small molecule alcohol chain extender and a catalyst are added and reacted at 50°C-90°C for 2h-6h until the residual NCO mass fraction reaches 5-7%, which is qualified; The catalyst is organic tin or organic bismuth, and the amount used is 0.5‰-5‰ of the mass of the polymer polyol; The process of chain extension of small molecule amine in step (1) is specifically as follows: The product obtained after hydrophilic chain extension is cooled to below 60°C, acetone is added in a ratio of 50-100% of the prepolymer mass, and then a small molecule polyamine chain extender is slowly added dropwise at 20-50°C; The neutralizing agent used in the neutralization operation in step (1) is triethylamine, and the neutralization degree is 90%-115%; the neutralization temperature is 10°C-50°C, and the time is 5-30 minutes; The process of slowly adding desalted water to the prepolymer obtained in step (1) under high-speed dispersion for emulsification in step (2) is specifically as follows: Under stirring at 1000-5000 r / min and controlling the temperature at 0°C-50°C, desalted water is slowly added to the prepolymer obtained in step (1), and the addition time of the desalted water is 2-3 hours, and the solid content of the prepolymer is finally made into 25-35%, and the rest is desalted water. Immediately after the addition of the desalted water, an aqueous solution miscible with the organosilicon modifier and the desalted water is added, and the mass ratio of the organosilicon modifier to the desalted water is 1:20-100. After the addition, the mixture is stirred for 5-20 minutes to complete the emulsification process; The desolventizing operation conditions in step (3) are negative pressure ≤ -0.095 MPa and temperature 20°C-50°C.

10. The method for preparing the waterborne polyurethane self-matting varnish according to claim 9, characterized in that: The specific process of prepolymerization in step (1) is as follows: Cool the dehydrated polymer polyol and dihydroxy silicone intermediate to below 85°C, and simultaneously add isocyanate and small molecule polyol to react at 60°C-85°C for 1.5h-3h; The process of hydrophilic chain extension in step (1) is specifically as follows: After the prepolymerization is completed by detecting that the residual NCO mass fraction reaches 9-12%, a carboxyl-containing dihydroxy small molecule alcohol chain extender and a catalyst are added, and the reaction is carried out at 60°C-90°C for 2h-5h until the residual NCO mass fraction reaches 5-7%, which is qualified; The process of chain extension of the small molecule amine in step (1) is specifically as follows: The product obtained after hydrophilic chain extension is cooled to below 55°C, diluted with solvent, and then a small molecule polyamine chain extender is slowly added dropwise at 20°C-45°C; The process of slowly adding desalted water to the prepolymer obtained in step (1) under high-speed dispersion for emulsification in step (2) is specifically as follows: Under stirring at 1000-2000 r / min, the temperature is controlled at 0°C-40°C, and desalted water is slowly added to the reaction product obtained in step (1). The solid content of the prepolymer is 25-30%. The rotation speed is adjusted to 3000-4000 r / min as the viscosity increases. After the phase inversion is completed, the rotation speed is adjusted to 1000-2000 r / min. After the addition of the desalted water, an aqueous solution miscible with the organosilicon modifier and the desalted water is immediately added. The mass ratio of the organosilicon modifier to the desalted water is 1:

50. The whole process is controlled for 15-90 minutes. After the addition is completed, stirring is carried out for 10-30 minutes to complete the emulsification process.

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