Waterborne polyurethane resin emulsion as well as preparation method and application thereof

Abstract

The invention provides a waterborne polyurethane resin emulsion as well as a preparation method and application thereof, and particularly relates to an organic silicon modified waterborne polyurethane resin emulsion as well as a preparation method and application thereof. The waterborne polyurethane resin emulsion is prepared from the following raw materials in parts by weight: 50 to 100 parts of polymer polyol, 2 to 15 parts of organosilicon polyol, 15 to 40 parts of diisocyanate, 2 to 5 parts of a hydrophilic chain extender, 0.2 to 1 part of a non-hydrophilic alcohol chain extender, 1 to 4 parts of a neutralizing agent and 1.5 to 6 parts of a post chain extender. According to the preparation method disclosed by the invention, the preparation raw materials of the waterborne polyurethane resin emulsion are designed, and the organic silicon polyol is further used, so that the waterborne polyurethane resin with relatively good water resistance, relatively good weather resistance, relatively good wear resistance and relatively high transparency is prepared; the synthetic leather prepared from the waterborne polyurethane resin emulsion is soft and smooth in hand feeling and relatively good in wear resistance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waterborne polyurethane, and particularly relates to a waterborne polyurethane resin emulsion, a preparation method and application thereof, and more particularly relates to a silicone-modified waterborne polyurethane resin emulsion, a preparation method and application thereof. BACKGROUND

[0002] Waterborne polyurethane (WPU) is widely used in synthetic leather, coatings and adhesives due to its low volatile organic compounds (VOC), environmental protection, non-toxicity and good film-forming property. CN208618163U discloses a waterborne polyurethane synthetic leather, which comprises a wet base structure and a bottom structure. The wet base structure is composed of a base cloth layer and a waterborne polyurethane layer uniformly coated on the upper surface of the base cloth layer. The lower surface of the polyester fiber layer in the synthetic leather provided by the technical solution is uniformly coated with a nano-silver adhesive layer mixed with nano-silver. The nano-silver composition in the nano-silver adhesive layer makes the whole have the functions of antistatic, antibacterial and odor elimination. Moreover, the bamboo charcoal fiber also has the function of relieving and eliminating odor, effectively reducing the odor of the whole synthetic leather. CN118241492A discloses a waterborne polyurethane synthetic leather and a preparation method thereof. The waterborne polyurethane synthetic leather comprises a base cloth, a surface layer, an adhesive layer and a foaming layer. The surface of the base cloth is sequentially compounded with the adhesive layer, the foaming layer and the surface layer. The adhesive layer comprises the following raw materials by weight: polyether polyol 20-30 parts, isocyanate 50-60 parts, catalyst 0.3-0.5 parts, chain extender 0.5-1 part, methyl methacrylate 20-30 parts, methacrylic acid 30-40 parts, initiator 0.5-0.8 parts, glycidyl methacrylate 10-20 parts, thickening agent 5-10 parts, and crosslinking agent 3-5 parts. The polyurethane synthetic leather provided by the technical solution can improve the adhesive strength of the polyurethane synthetic leather system, reduce the peeling phenomenon of the polyurethane synthetic leather, and prolong the service life of the polyurethane synthetic leather by using the combination of acrylate and polyurethane.

[0003] However, the conventional waterborne polyurethane still has the following disadvantages: poor weather resistance, easy yellowing and powdering under ultraviolet light and heat environment, affecting the appearance and service life of the synthetic leather; insufficient water resistance, the film layer is easy to swell and the strength decreases due to the presence of hydrophilic groups when it is exposed to moisture for a long time; and contradiction between hand feeling and wear resistance, the ordinary WPU surface layer is soft but sticky and not smooth, and the wear resistance is insufficient. If the hardness is increased to improve the smoothness, the hand feeling will be poor.

[0004] Silicone materials are widely studied due to its low surface energy, excellent weather resistance and smooth feel. However, simple external addition of silicone auxiliary can cause resin delamination and silicone oil precipitation and other problems; if a reactive silicone is used, due to poor compatibility of silicone with the waterborne polyurethane system, the reaction process appears system out of slag, resin film whitening and other problems. Therefore, how to provide a waterborne polyurethane with good water resistance, weather resistance and wear resistance through reasonable molecular design has become a technical problem to be solved. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a waterborne polyurethane resin emulsion and its preparation method and application, more specifically to an organic silicon modified waterborne polyurethane resin emulsion and its preparation method and application. The present application designs the raw materials for preparing the waterborne polyurethane resin emulsion, and further uses organic silicone polyols to prepare a waterborne polyurethane resin with good water resistance, good weather resistance, good wear resistance and high transparency. The synthetic leather prepared from the waterborne polyurethane resin emulsion has a smooth feel and good wear resistance.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a waterborne polyurethane resin emulsion, the raw materials for preparing the waterborne polyurethane resin emulsion include the following components in the following weight fractions: polymeric polyol 50-100 parts, organic silicone polyol 2-15 parts, diisocyanate 15-40 parts, hydrophilic chain extender 2-5 parts, non-hydrophilic alcohol chain extender 0.2-1 part, neutralizing agent 1-4 parts, post chain extender 1.5-6 parts.

[0008] The present application designs the raw materials for preparing the waterborne polyurethane resin emulsion, and further uses organic silicone polyols to prepare a waterborne polyurethane resin with good water resistance, good weather resistance, good wear resistance and high transparency. The synthetic leather prepared from the waterborne polyurethane resin emulsion has a smooth feel and good wear resistance. Specifically, the present application chemically bonds the organic silicone segment to the polyurethane segment by copolymerization, solving the problem of poor compatibility of silicone with the waterborne polyurethane system, easy precipitation or phase separation, improving the gloss and transparency of the waterborne polyurethane resin; the introduction of the organic silicone segment can make the film surface smooth and reduce the friction coefficient, thereby improving the wear resistance under certain conditions. At the same time, the reduction of low polarity segments in the organic silicone polyol can reduce the exposure of hydrophilic groups in the latex particles, improving the water resistance of the waterborne polyurethane resin; and the high stability of the silicon-oxygen bond in the organic silicone polyol can enhance the ultraviolet resistance and high temperature resistance of the waterborne polyurethane resin, making the synthetic leather prepared from the waterborne polyurethane resin emulsion less prone to yellowing.

[0009] In the present application, by controlling the amount of silicone polyol within a specific range, a water-based polyurethane resin emulsion with excellent comprehensive performance is prepared. If the amount of silicone polyol in the raw materials for preparing the water-based polyurethane resin is too much, due to the strong hydrophobicity of the silicone segment in the silicone polyol and the too long silicone segment, the surface of the polyurethane prepolymer particles will be covered with silicone segments, reducing the hydrophilicity of the water phase and the surface charge stability of the water-based polyurethane resin emulsion, resulting in unstable stability of the water-based polyurethane resin emulsion prepared. The decrease in emulsion stability may lead to uncontrollable particle size growth or agglomeration during the chain extension stage, thereby affecting the film forming quality. Due to the excessively low surface energy of the polyurethane film layer, the adhesion of the polyurethane film layer to the substrate is affected, and problems such as pinholes, surface wrinkles or poor leveling may occur during the film forming process, which may also increase the cost. If the amount of silicone polyol in the raw materials for preparing the water-based polyurethane resin emulsion is too small, the water resistance and weather resistance of the water-based polyurethane resin prepared finally are poor, and the touch of the synthetic leather prepared from the water-based polyurethane resin emulsion is poor. Moreover, the water contact angle of the synthetic leather surface layer prepared from the water-based polyurethane resin is limited, and the waterproof and smoothness of the synthetic leather surface layer is not significantly improved.

[0010] In the present application, the weight fraction of the polymer polyol in the raw materials for preparing the water-based polyurethane resin emulsion can be 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, 75 parts, 80 parts, 85 parts, 90 parts, 95 parts or 100 parts, etc.

[0011] The weight fraction of the silicone polyol in the raw materials for preparing the water-based polyurethane resin emulsion can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts or 15 parts, etc.

[0012] The weight fraction of the diisocyanate in the raw materials for preparing the water-based polyurethane resin emulsion can be 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 27 parts, 30 parts, 33 parts, 36 parts, 38 parts or 40 parts, etc.

[0013] The weight fraction of the hydrophilic chain extender in the raw materials for preparing the water-based polyurethane resin emulsion can be 2 parts, 2.3 parts, 2.5 parts, 2.7 parts, 3 parts, 3.3 parts, 3.6 parts, 3.8 parts, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts or 5 parts, etc.

[0014] The weight fraction of the neutralizing agent in the raw materials for preparing the water-based polyurethane resin emulsion can be 1 part, 1.3 parts, 1.5 parts, 1.8 parts, 2 parts, 2.2 parts, 2.5 parts, 2.7 parts, 3 parts, 3.3 parts, 3.5 parts, 3.8 parts or 4 parts, etc.

[0015] The weight fraction of the post-chain extender in the raw material for preparing the aqueous polyurethane resin emulsion can be 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, or 6 parts, etc.

[0016] The following is a preferred technical solution of the present application, but not as a limitation on the technical solutions provided by the present application. Through the following preferred technical solution, the purpose and beneficial effects of the present application can be better achieved and realized.

[0017] Preferably, the organosilicon polyol comprises an organosilicon diol.

[0018] Preferably, the organosilicon polyol comprises a terminal hydroxyl polydimethylsiloxane.

[0019] Preferably, the number average molecular weight of the organosilicon polyol is 2000-5000, for example, it can be 2000, 2200, 2500, 2700, 3000, 3300, 3600, 3800, 4000, 4200, 4400, 4600, 4800, or 5000, etc.

[0020] Preferably, the organosilicon polyol has the following structure shown in Formula I:

[0021] Formula I;

[0022] wherein each R independently represents a C1-C10 (for example, it can be C1, C2, C3, C4, C5, C6, C7, C8, C9, or C10) alkylene group;

[0023] n represents an integer of 0-30 (for example, it can be 0, 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30, etc.), and m represents an integer between 1-30 (for example, it can be 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, or 30, etc.).

[0024] In the present application, the organosilicon polyol with the structure shown in Formula I can further improve the comprehensive performance of the aqueous polyurethane resin. Specifically, the Si-O main chain and long alkyl side chain (-C 10 H 21 ) in the organosilicon polyol with the structure shown in Formula I both have very low surface energy (20-22 mN / m), and during the curing process of the polyurethane, the silicon-oxygen chain in the organosilicon polyol and the long alkyl side chain tend to migrate to the surface of the polyurethane film layer, forming a silicon-rich layer, which significantly improves the smoothness, water resistance, and chemical corrosion resistance of the synthetic leather surface layer.

[0025] Preferably, the organosilicon polyol in the raw materials for preparing the waterborne polyurethane resin emulsion is 5-12 parts by weight, for example, 5, 6, 7, 8, 9, 10, 11 or 12 parts, etc.

[0026] This invention further improves the overall performance of waterborne polyurethane resin emulsions by adjusting the weight of organosilicon polyols in the raw materials for preparing waterborne polyurethane resin emulsions to 5-12 parts.

[0027] Preferably, the polymeric polyol comprises any one or a combination of at least two of polypropylene glycol, polytetrahydrofuran glycol (PTMEG), or polycarbonate glycol (PCDL), and is more preferably polytetrahydrofuran glycol and / or polycarbonate glycol.

[0028] Preferably, the number average molecular weight of the polymer polyol is 1000-3000 (e.g., 1000, 1200, 1400, 1600, 1800, 2000, 2200, 2500, 2700 or 3000, etc.), and more preferably 1000-2500.

[0029] Preferably, the diisocyanate includes aliphatic diisocyanates.

[0030] Preferably, the aliphatic diisocyanate includes any one or a combination of at least two of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), or dicyclohexylmethane diisocyanate (HMDI).

[0031] Preferably, the hydrophilic chain extender includes any one or a combination of at least two of dimethylolpropionic acid, dimethylolbutyric acid, or sodium ethylenediamine ethanesulfonate.

[0032] Preferably, the non-hydrophilic alcohol chain extender includes any one or a combination of at least two of 1,4-butanediol, 1,6-hexanediol, or trimethylolpropane.

[0033] Preferably, the neutralizing agent includes any one or a combination of at least two of triethylamine, ammonia, N-methylmorpholine, N-ethylmorpholine, N-methyldiethanolamine, or sodium hydroxide.

[0034] Preferably, the post-chain extender includes an amine chain extender.

[0035] Preferably, the amine chain extender includes any one or a combination of at least two of ethylenediamine, propylenediamine, isofluranediamine, hydrazine hydrate, 2,4-toluenediamine, 2-methyl-1,5-pentanediamine, piperazine, or hexamethylenediamine.

[0036] Preferably, the raw materials for preparing the waterborne polyurethane resin emulsion further include 0.01-0.2 parts by weight of catalyst, for example, 0.01 parts by weight, 0.02 parts by weight, 0.04 parts by weight, 0.06 parts by weight, 0.08 parts by weight, 0.1 parts by weight, 0.12 parts by weight, 0.14 parts by weight, 0.16 parts by weight, 0.18 parts by weight, or 0.2 parts by weight.

[0037] Preferably, the catalyst comprises any one or a combination of at least two of dibutyltin dilaurate, stannous octoate, tetramethylbutanediamine, or triethylenediamine.

[0038] Preferably, the raw materials for preparing the waterborne polyurethane resin emulsion further include 50-200 parts by weight of organic solvent, such as 50 parts by weight, 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, 100 parts by weight, 120 parts by weight, 140 parts by weight, 160 parts by weight, 180 parts by weight, or 200 parts by weight.

[0039] Preferably, the organic solvent includes acetone and / or butanone.

[0040] Preferably, the raw materials for preparing the waterborne polyurethane resin emulsion also include 100-300 parts by weight of water, for example, 100 parts by weight, 120 parts by weight, 140 parts by weight, 160 parts by weight, 180 parts by weight, 200 parts by weight, 220 parts by weight, 240 parts by weight, 260 parts by weight, 280 parts by weight, or 300 parts by weight.

[0041] Preferably, the water comprises deionized water.

[0042] In a second aspect, the present invention provides a method for preparing an aqueous polyurethane resin emulsion as described in the first aspect, the preparation method comprising the following steps:

[0043] (1) Prepolymerization reaction: Polymer polyol, organosilicon diol and diisocyanate undergo a prepolymerization reaction to obtain polyurethane prepolymer;

[0044] (2) Introducing hydrophilic groups: The reaction system obtained in step (1) is mixed with hydrophilic chain extender, non-hydrophilic alcohol chain extender, optional catalyst and part of organic solvent, and reacted to obtain hydrophilic modified polyurethane prepolymer;

[0045] (3) Neutralization reaction: The hydrophilic group modified polyurethane prepolymer obtained in step (2), the neutralizing agent and the remaining organic solvent are mixed and a neutralization reaction is carried out;

[0046] (4) Emulsification: Add water to the reaction system obtained in step (3), emulsify, and disperse;

[0047] (5) Chain extension reaction: The reaction system obtained in step (4) is mixed with the post-chain extender and a chain extension reaction is carried out to obtain the waterborne polyurethane resin emulsion.

[0048] Preferably, the temperature of the prepolymerization reaction is 80-90℃, for example, it can be 80℃, 81℃, 82℃, 83℃, 84℃, 85℃, 86℃, 87℃, 88℃, 89℃ or 90℃.

[0049] Preferably, the prepolymerization reaction time is 2-4 h, for example, it can be 2 h, 2.5 h, 3 h, 3.5 h or 4 h.

[0050] Preferably, the prepolymerization reaction further includes a pretreatment step, wherein the pretreatment method includes vacuum dehydration of the polymer polyol and organosilicon diol.

[0051] Preferably, the temperature of the vacuum dehydration treatment is 90-120℃ (e.g., 90℃, 93℃, 96℃, 99℃, 102℃, 105℃, 108℃, 110℃, 113℃, 115℃, 117℃, or 120℃, etc.), and the time is 20-60 min (e.g., 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, or 60 min, etc.).

[0052] Preferably, the reaction temperature in step (2) is 50-70℃, for example, it can be 50℃, 52℃, 54℃, 56℃, 58℃, 60℃, 62℃, 64℃, 66℃, 68℃ or 70℃, etc.

[0053] Preferably, the reaction time in step (2) is 2-4 h, for example, it can be 2 h, 2.5 h, 3 h, 3.5 h or 4 h.

[0054] Preferably, step (3) further includes a step of cooling the hydrophilic group modified polyurethane prepolymer obtained in step (2) to below 40°C (e.g., 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C or 40°C, etc.) before mixing.

[0055] Preferably, the temperature of the neutralization reaction in step (3) is 20-40℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃ or 40℃, etc.

[0056] Preferably, the neutralization reaction time in step (3) is 1-5 min, for example, it can be 1 min, 2 min, 3 min, 4 min or 5 min, etc.

[0057] Preferably, the dispersion time in step (4) is ≤3 min, for example, it can be 1 min, 2 min or 3 min.

[0058] Preferably, the stirring speed for dispersion in step (4) is 1500-1800 rpm; for example, it can be 1500 rpm, 1520 rpm, 1550 rpm, 1570 rpm, 1600 rpm, 1630 rpm, 1660 rpm, 1680 rpm, 1700 rpm, 1720 rpm, 1750 rpm, 1780 rpm or 1800 rpm, etc.

[0059] Preferably, the method of adding water in step (4) includes dripping.

[0060] Preferably, the temperature of the chain extension reaction in step (5) is 20-40℃, for example, it can be 20℃, 22℃, 24℃, 26℃, 28℃, 30℃, 32℃, 34℃, 36℃, 38℃ or 40℃, etc.

[0061] Preferably, the chain extension reaction time in step (5) is 5-10 min, for example, it can be 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0062] Preferably, the chain extension reaction in step (5) further includes a post-treatment step, wherein the post-treatment method includes: removing the organic solvent at -0.8 MPa ~ -0.1 MPa (e.g., -0.8 MPa, -0.7 MPa, -0.6 MPa, -0.5 MPa, -0.4 MPa, -0.3 MPa, -0.2 MPa or -0.1 MPa, etc.).

[0063] Preferably, the solid content of the waterborne polyurethane resin emulsion is 30-45%, for example, it can be 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44% or 45%, etc.

[0064] Preferably, the particle size of the aqueous polyurethane resin emulsion is 60-120 nm, for example, it can be 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm or 120 nm.

[0065] Preferably, the preparation method of the aqueous polyurethane resin emulsion specifically includes the following steps:

[0066] (1) Prepolymerization reaction: The polymer polyol and organosilicon diol are subjected to vacuum dehydration treatment at 90-120℃ for 20-60 min;

[0067] The polymer polyol and organosilicon diol, which have undergone vacuum dehydration, are subjected to a prepolymerization reaction with diisocyanate at 80-90℃ for 2-4 h to obtain a polyurethane prepolymer.

[0068] (2) Introducing hydrophilic groups: The reaction system obtained in step (1) is mixed with hydrophilic chain extender, optional catalyst and part of organic solvent, and reacted at 50-70℃ for 2-4 h to obtain hydrophilic modified polyurethane prepolymer;

[0069] (3) Neutralization reaction: The hydrophilic group modified polyurethane prepolymer obtained in step (2), the neutralizing agent and the remaining organic solvent are mixed and neutralized at 20-40℃ for 1-5 min;

[0070] (4) Emulsification: Add water dropwise to the reaction system obtained in step (3), emulsify, disperse, and disperse for ≤3 min;

[0071] (5) Chain extension reaction: The reaction system obtained in step (4) is mixed with the post-chain extender and subjected to a chain extension reaction at 20-40℃ for 5-10 min. Then, the organic solvent and water are removed at -0.8 MPa ~ -0.1 MPa to obtain the waterborne polyurethane resin emulsion.

[0072] Thirdly, the present invention provides an application of the waterborne polyurethane resin emulsion as described in the first aspect, wherein the waterborne polyurethane resin emulsion is used to prepare a synthetic leather surface layer.

[0073] Synthetic leather prepared from the waterborne polyurethane resin emulsion provided by this invention can be used to prepare sports shoes, furniture, automotive interiors, outdoor functional products, etc.

[0074] Compared with the prior art, the present invention has the following beneficial effects:

[0075] (1) By designing the raw materials for preparing waterborne polyurethane resin emulsion, and further by using organosilicon polyols and controlling their dosage within a specific range, this invention prepares waterborne polyurethane resin emulsion with good water resistance, good weather resistance, good wear resistance and high transparency. The synthetic leather prepared from the waterborne polyurethane resin emulsion has a smooth feel and high wear resistance.

[0076] (2) By using polymer polyols (polytetrahydrofuran diol and / or polycarbonate diol) and organosilicon polyols with the structure of Formula I, the present invention further improves the comprehensive performance of waterborne polyurethane resin emulsion and synthetic leather surface layer.

[0077] (3) The present invention further regulates the amount of organosilicon polyol in the raw materials for preparing waterborne polyurethane resin emulsion to 5-12 parts by weight, which further improves the comprehensive performance of waterborne polyurethane resin emulsion and synthetic leather surface layer. Detailed Implementation

[0078] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0079] The sources of some components in the examples and comparative examples are as follows:

[0080] Polycarbonate diol (PCDL): number average molecular weight 2000, purchased from Ube Industries, Japan, brand name UH-200;

[0081] Polytetrahydrofuran diol (PTMEG): Number average molecular weight 2000, purchased from Hyosung Chemical, brand name PTMEG2000G;

[0082] Polypropylene oxide glycol: number average molecular weight 2000, purchased from Wanhua Chemical, brand name C2020;

[0083] Organosilicon diol 1: Number average molecular weight of 4500, having the structure shown in Formula I, purchased from Sloco, brand name 8865H;

[0084] Organosilicon diol 2: Number average molecular weight of 3000, having the structure shown in Formula I, purchased from Sloco, brand name 8814;

[0085] Organosilicon diol 3: Number average molecular weight of 2000, having the structure shown in Formula I, purchased from Sloco, brand name 8815;

[0086] Organosilicon polyol 4: number average molecular weight 2200, possesses... The structure (R1 and R2 each independently represent a hydrogen atom or a C1-C5 alkyl group, R3 represents a C1-C8 alkylene group, and n represents an integer between 10 and 100) was purchased from Shanghai Tiger, Tech-2147.

[0087] Example 1

[0088] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 88 parts of polytetrahydrofuran diol, 16 parts of organosilicon polyol, 24 parts of isophorone diisocyanate, 4 parts of dimethylolpropionic acid, 0.5 parts of 1,4-butanediol, 3.3 parts of triethylamine, 2.2 parts of ethylenediamine, 0.05 parts of stannous octoate, 100 parts of acetone, and 235 parts of deionized water.

[0089] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as follows:

[0090] (1) Prepolymerization reaction: Polytetrahydrofuran diol and organosilicon polyol 1 were subjected to vacuum dehydration treatment at 100℃ for 30 min;

[0091] The vacuum-dehydrated polytetrahydrofuran diol and organosilicon polyol 1 were subjected to a prepolymerization reaction with isophorone diisocyanate at 90°C for 2 h to obtain a polyurethane prepolymer.

[0092] (2) Introducing hydrophilic groups: Dimethylolpropionic acid, 1,4-butanediol, stannous octoate and acetone (50 parts by weight) were added to the reaction system obtained in step (1) and mixed. The mixture was reacted at 60°C for 2 h to obtain hydrophilic modified polyurethane prepolymer.

[0093] (3) Neutralization reaction: Cool the hydrophilic group modified polyurethane prepolymer obtained in step (2) to 30°C, add triethylamine and the remaining acetone (50 parts by weight) to it and mix, and carry out a neutralization reaction at 30°C for 3 min;

[0094] (4) Emulsification: Add deionized water dropwise to the reaction system obtained in step (3), emulsify, disperse, and disperse for ≤3 min;

[0095] (5) Chain extension reaction: Ethylenediamine was added to the reaction system obtained in step (4) and mixed. After the chain extension reaction was carried out at 30°C for 10 min, acetone was removed at -0.5 MPa to obtain the aqueous polyurethane resin emulsion.

[0096] Example 2

[0097] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 88 parts of polycarbonate diol, 18 parts of organosilicon polyol, 20 parts of dicyclohexylmethane diisocyanate, 5 parts of isophorone diisocyanate, 4 parts of dimethylolpropionic acid, 0.5 parts of 1,4-butanediol, 3.3 parts of triethylamine, 2.1 parts of ethylenediamine, 0.05 parts of stannous octoate, 100 parts of acetone, and 243 parts of deionized water.

[0098] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as follows:

[0099] (1) Prepolymerization reaction: Polycarbonate diol and organosilicon polyol 1 were subjected to vacuum dehydration treatment at 100℃ for 30 min;

[0100] The vacuum-dehydrated polycarbonate diol and organosilicon polyol 1 were subjected to a prepolymerization reaction with dicyclohexylmethane diisocyanate and isophorone diisocyanate at 85°C for 3 h to obtain a polyurethane prepolymer.

[0101] (2) Introducing hydrophilic groups: Dimethylolpropionic acid, 1,4-butanediol, stannous octoate and acetone (50 parts by weight) were added to the reaction system obtained in step (1) and mixed. The mixture was reacted at 50°C for 3 h to obtain hydrophilic modified polyurethane prepolymer.

[0102] (3) Neutralization reaction: Cool the hydrophilic group modified polyurethane prepolymer obtained in step (2) to 30°C, add triethylamine and the remaining acetone (50 parts by weight) to it and mix, and carry out a neutralization reaction at 30°C for 3 min;

[0103] (4) Emulsification: Add deionized water dropwise to the reaction system obtained in step (3), emulsify, disperse, and disperse for ≤3 min;

[0104] (5) Chain extension reaction: Ethylenediamine was added to the reaction system obtained in step (4) and mixed. After the chain extension reaction was carried out at 30°C for 10 min, acetone was removed at -0.5 MPa to obtain the aqueous polyurethane resin emulsion.

[0105] Example 3

[0106] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 88 parts of polytetrahydrofuran diol, 110 parts of organosilicon polyol, 20 parts of isophorone diisocyanate, 10 parts of hexamethylene diisocyanate, 4 parts of dimethylolpropionic acid, 0.5 parts of trimethylolpropane, 3.3 parts of triethylamine, 2.2 parts of ethylenediamine, 0.05 parts of stannous octoate, 100 parts of acetone, and 254 parts of deionized water.

[0107] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as follows:

[0108] (1) Prepolymerization reaction: Polytetrahydrofuran diol and organosilicon polyol 1 were subjected to vacuum dehydration treatment at 100℃ for 30 min;

[0109] The vacuum-dehydrated polytetrahydrofuran diol and organosilicon polyol 1 were subjected to a prepolymerization reaction with isophorone diisocyanate at 80°C for 4 h to obtain a polyurethane prepolymer.

[0110] (2) Introducing hydrophilic groups: Dimethylolpropionic acid, trimethylolpropane, stannous octoate and acetone (50 parts by weight) were added to the reaction system obtained in step (1) and mixed. The mixture was reacted at 60°C for 2 h to obtain hydrophilic modified polyurethane prepolymer.

[0111] (3) Neutralization reaction: Cool the hydrophilic group modified polyurethane prepolymer obtained in step (2) to 30°C, add triethylamine and the remaining acetone (50 parts by weight) to it and mix, and carry out a neutralization reaction at 30°C for 3 min;

[0112] (4) Emulsification: Add deionized water dropwise to the reaction system obtained in step (3), emulsify, disperse, and disperse for ≤3 min;

[0113] (5) Chain extension reaction: Ethylenediamine was added to the reaction system obtained in step (4) and mixed. After the chain extension reaction was carried out at 30°C for 10 min, acetone was removed at -0.5 MPa to obtain the aqueous polyurethane resin emulsion.

[0114] Example 4

[0115] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 88 parts of polytetrahydrofuran diol, 26 parts of organosilicon polyol, 24 parts of isophorone diisocyanate, 4 parts of dimethylolpropionic acid, 0.5 parts of 1,4-butanediol, 3.3 parts of triethylamine, 2.0 parts of ethylenediamine, 0.05 parts of stannous octoate, 100 parts of acetone, and 234 parts of deionized water.

[0116] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as described in Example 1.

[0117] Example 5

[0118] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 88 parts of polytetrahydrofuran diol, 36 parts of organosilicon polyol, 24 parts of isophorone diisocyanate, 4 parts of dimethylolpropionic acid, 0.5 parts of 1,4-butanediol, 3.3 parts of triethylamine, 1.8 parts of ethylenediamine, 0.05 parts of stannous octoate, 100 parts of acetone, and 232 parts of deionized water.

[0119] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as described in Example 1.

[0120] Example 6

[0121] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 60 parts of polytetrahydrofuran diol, 312 parts of organosilicon polyol, 16 parts of isophorone diisocyanate, 2 parts of dimethylolpropionic acid, 1.5 parts of triethylamine, 4 parts of ethylenediamine, 0.1 parts of stannous octoate, 100 parts of acetone, and 177 parts of deionized water.

[0122] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as described in Example 1.

[0123] Example 7

[0124] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 70 parts of polytetrahydrofuran diol, 37 parts of organosilicon polyol, 20 parts of isophorone diisocyanate, 4.5 parts of dimethylolpropionic acid, 3.8 parts of triethylamine, 5.6 parts of ethylenediamine, 0.08 parts of stannous octoate, 100 parts of acetone, and 205 parts of deionized water.

[0125] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as described in Example 1.

[0126] Example 8

[0127] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 98 parts of polytetrahydrofuran diol, 39 parts of organosilicon polyol, 36 parts of dicyclohexylmethane diisocyanate, 3 parts of dimethylolpropionic acid, 2.5 parts of triethylamine, 3.4 parts of ethylenediamine, 0.05 parts of stannous octoate, 100 parts of acetone, and 282 parts of deionized water.

[0128] The preparation method of the above-mentioned waterborne polyurethane resin emulsion is as described in Example 1.

[0129] Example 9

[0130] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The only difference from Example 5 is that the raw materials for preparing the aqueous polyurethane resin emulsion contain 91 parts by weight of polytetrahydrofuran diol and 3 parts by weight of organosilicon polyol 3; other conditions are the same as in Example 5.

[0131] Example 10

[0132] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The only difference from Example 5 is that the raw materials for preparing the aqueous polyurethane resin emulsion contain 86 parts by weight of polytetrahydrofuran diol and 8 parts by weight of organosilicon polyol 3; other conditions are the same as in Example 5.

[0133] Example 11

[0134] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The only difference from Example 5 is that the raw materials for preparing the aqueous polyurethane resin emulsion contain 83 parts by weight of polytetrahydrofuran diol and 11 parts by weight of organosilicon polyol 3; other conditions are the same as in Example 5.

[0135] Example 12

[0136] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method. The only difference from Example 5 is that the raw materials for preparing the aqueous polyurethane resin emulsion contain 80 parts by weight of polytetrahydrofuran diol and 14 parts by weight of organosilicon polyol 3; other conditions are the same as in Example 5.

[0137] Example 13

[0138] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method, which differs from Example 5 only in that 88 parts by weight of polytetrahydrofuran diol is replaced with 88 parts by weight of polypropylene oxide diol; other conditions are the same as in Example 5.

[0139] Example 14

[0140] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method, which differs from Example 5 only in that 6 parts by weight of organosilicon polyol 3 is replaced with 6.7 parts by weight of organosilicon polyol 4; other conditions are the same as in Example 5.

[0141] Comparative Example 1

[0142] Comparative Example 1 provides an aqueous polyurethane resin emulsion and its preparation method. The only difference from Example 5 is that the raw materials for preparing the aqueous polyurethane resin emulsion contain 93 parts by weight of polytetrahydrofuran diol and 1 part by weight of organosilicon polyol 3; other conditions are the same as in Example 5.

[0143] Comparative Example 2

[0144] Comparative Example 1 provides an aqueous polyurethane resin emulsion and its preparation method, which differs from Example 5 only in that: the weight parts of polytetrahydrofuran diol and organosilicon polyol 3 in the raw materials for preparing the aqueous polyurethane resin emulsion are 64 parts and 30 parts respectively; other conditions are the same as in Example 5.

[0145] Comparative Example 3

[0146] This embodiment provides an aqueous polyurethane resin emulsion and its preparation method, which differs from Example 5 only in that: organosilicon polyol 3 is not used, and 88 parts by weight of polytetrahydrofuran diol is replaced with 94 parts by weight of polytetrahydrofuran diol; other conditions are the same as in Example 5.

[0147] The performance of the waterborne polyurethane resin emulsions provided in the above embodiments and comparative examples was tested, and the specific test methods are as follows:

[0148] (1) Solid content: Accurately weigh the weighing bottle using a balance and record it as M1 (g); add the water-based polyurethane resin emulsion sample to be tested (mass 1-2 g) to the weighing bottle, weigh the total mass and record it as M2 (g); put the weighing bottle containing the sample into an oven and dry it at 120℃ for 2 hours. Take out the dried weighing bottle, put it in a desiccator to cool to room temperature, and then weigh it again using a balance and record it as M3 (g); calculate the solid content: solid content (%) = (M3 - M1) / (M2 - M1) × 100%; repeat the test twice and take the average value as the solid content of the water-based polyurethane resin emulsion sample;

[0149] (2) Particle size: The particle size of the obtained waterborne polyurethane emulsion was determined using a Malvern laser particle size analyzer Zetasizer Nano. The specific steps are as follows: Take a certain amount of emulsion sample, dilute it with deionized water at a volume ratio of 1:20, and add it to the dispersion cell of the laser particle size analyzer. Click "Measure", the instrument collects the scattering signal, each measurement lasts for 10-30 seconds, and each sample is measured at least 3 times to determine the repeatability of the test and record the emulsion particle size.

[0150] (3) pH: Before testing, the Leici PHSJ-4F pH meter was calibrated from pH 6.86 to pH 4.00. The electrode was inserted into the PUD sample and submerged in the liquid for 2-3 cm. The electrode was gently stirred to ensure that the electrode surface was in full contact with the emulsion. The reading was allowed to stabilize (about 10-60 seconds), and the pH value was recorded.

[0151] The waterborne polyurethane resin emulsion provided in the above embodiments or comparative examples was used to prepare the test sample, and then the performance was tested. The preparation method of the test sample is as follows: The waterborne polyurethane resin emulsion and thickener (purchased from Borchi, brand name Gel 0625) were mixed to prepare a slurry with a viscosity of 10000 cp at 23℃±2℃ (the viscosity test method is to select Brookfield dial viscometer rotor No. 4 and dial speed of 30 rpm. When the dial is stable during the test, the dial reading * 200cp is the viscosity of the test sample). The slurry was coated on mirror release paper and coated into a film with a thickness of 600 μm (wet film). The film was cured by heating in an oven at 50℃@10min, 70℃@10min, 90℃@10min, 110℃@10min, and 135℃@5min in sequence to obtain a polyurethane film layer on one side of the mirror release paper, thus completing the preparation of the test sample.

[0152] The specific performance testing methods are as follows:

[0153] (4) Water contact angle: 5.0 μL of deionized water was dropped onto one side of the polyurethane film layer of the sample to be tested. The measurement surface was kept horizontal. The initial contact angle was measured within 5 s after the water drop was dropped using a water contact angle tester. The measurement was repeated at 5 different locations, and the average value was taken as the final test result.

[0154] (5) Water absorption rate: Peel off the mirror release paper from the sample to be tested, retain the polyurethane film layer, cut it into a sample of 20×20mm, dry it and perform constant weight treatment (105℃, to constant weight) to obtain a dry film, weigh it (recorded as m1, g), immerse the dry film in deionized water at room temperature (23±2℃) for 24 h (avoid air bubbles adhering), take it out and quickly absorb the surface water droplets with filter paper (without wiping) to obtain a wet film, weigh it (recorded as m2, g); calculate the water absorption rate, water absorption rate (%) = [(m2–m1) / m1]×100%; repeat the test 5 times and take the average value as the final test result;

[0155] (6) Tensile strength: Cut the prepared polyurethane film into 25mm×60mm specifications and test and record the thickness of the film. Use the Instron universal testing machine to clamp the sample, ensuring that it is clamped tightly but not damaged. Click the test button and wait for the machine to continuously stretch the sample until it breaks. Record the tensile strength obtained from the test.

[0156] (7) Elongation at break: Cut the prepared polyurethane film into 25mm×60mm specifications and test and record the thickness of the film. Use the Instron universal testing machine to clamp the sample, ensuring that it is clamped tightly but not damaged. Click the test button and wait for the machine to continuously stretch the sample until it breaks. Record the elongation at break obtained from the test.

[0157] (8) Martindale abrasion resistance: Fix the sample to be tested on the fixture in the Martindale abrasion tester, with the test surface (polyurethane film) facing down and in contact with the wool cloth. Apply a pressure of 12 kPa to the sample to be tested; start the instrument and the sample to be tested moves in a curved trajectory relative to the abrasive; set the number of cycles and the cycle speed to 60 rpm, and observe the surface of the polyurethane film after the set number of cycles is stopped. Test until the surface of the polyurethane film is damaged, and record the corresponding number of cycles.

[0158] (9) Taber abrasion resistance: The test reference standard is ASTM D4060 (coating abrasion resistance), and the test instrument is Taber abrasion tester (test H-18 grinding wheel). Remove the mirror release paper from the sample to obtain the sample. Fix the sample on the sample plate and record the initial mass m3 (g). Run the Taber machine at the set speed (1000 rpm). After the test, clean the sample and weigh it m4 (g). Calculate the mass loss Δm = m3 − m4. Repeat the above test 5 times and take the average value as the final test result.

[0159] (10) Yellowing resistance: Place the sample to be tested into the aging chamber and run it in a cycle for 72 hours as described above, and evaluate it according to the visual yellowing level (1-5).

[0160] (11) Hand feel evaluation: Lay the tested samples flat on a flat surface and gently slide them along the surface with clean fingers to feel whether they are smooth and whether the resistance is uniform.

[0161] The results of the above performance tests are shown in Table 1-2 below:

[0162] Table 1

[0163]

[0164] Table 2

[0165]

[0166] As can be seen from the above, this invention designs the raw materials for preparing waterborne polyurethane resin emulsions and further uses organosilicon polyols, controlling their dosage within a specific range, to prepare waterborne polyurethane resin emulsions with good water resistance, good weather resistance, good abrasion resistance, and high transparency. The synthetic leather prepared from these waterborne polyurethane resin emulsions has a smooth feel and high abrasion resistance. The waterborne polyurethane resin emulsion provided by this invention has a particle size of 56-145 nm and a pH value of 7.1-7.8. The polyurethane film prepared from the waterborne polyurethane resin emulsion provided by this invention has a water contact angle of 75°-118°, a water absorption rate of 5.0-12.8%, a tensile strength of 15-40 MPa, an elongation at break of 510-700%, a Martindale abrasion resistance of 100 million to 100 million cycles, a mass loss of 0.032-1.220 g after Taber abrasion resistance (1000 rpm) test, and a yellowing grade of 3-5 after yellowing resistance test. The prepared polyurethane film has a smooth / smooth feel.

[0167] As can be seen from the comparison of Examples 1-12 and Examples 13-14, the present invention further improves the comprehensive performance of waterborne polyurethane resin emulsion and synthetic leather surface layer by using polymer polyols (polytetrahydrofuran diol and / or polycarbonate diol) and organosilicon polyols with Formula I structure.

[0168] In comparative examples 6-8, with different synthetic formulations, as the amount of organosilicon glycol 3 increased, the water contact angle increased, the water absorption rate decreased, and the yellowing resistance improved. The polyurethane film in Example 7 had a water contact angle of 92°, a water absorption rate of 5.2%, a tensile strength of 30 MPa, an elongation at break of 650%, a Martindale abrasion resistance of 55,000 cycles, a mass loss of 0.053 g after a Taber abrasion resistance test (1000 rpm), and a yellowing resistance rating of 4-5. Furthermore, the prepared polyurethane film had a smooth feel. Example 8: The polyurethane film has a water contact angle of 95°, a water absorption rate of 6.1%, a tensile strength of 33 MPa, an elongation at break of 700%, a Martindale abrasion resistance of 75,000 cycles, a mass loss of 0.042 g after a Taber abrasion resistance test (1000 rpm), and a yellowing grade of 4-5 after a yellowing resistance test. The prepared polyurethane film has a smooth feel. Example 6: The polyurethane film has a water contact angle of 110°, a water absorption rate of 5.0%, a tensile strength of 27 MPa, an elongation at break of 600%, a Martindale abrasion resistance of 55,000 cycles, a mass loss of 0.055 g after a Taber abrasion resistance test (1000 rpm), and a yellowing grade of 5 after a yellowing resistance test. The prepared polyurethane film also has a smooth feel.

[0169] Compared to Example 5, the polyurethane film of Example 13 had a water contact angle of 75°, a water absorption rate of 12.9%, a tensile strength of 15 MPa, an elongation at break of 700%, a Martindale abrasion resistance of 10,000 cycles, a mass loss of 1.220 g after a Taber abrasion resistance test (1000 rpm), and a yellowing grade of 3 after a yellowing resistance test. The prepared polyurethane film also had a relatively rough feel. Compared to Example 5, the contact angle increased by 11°, the water absorption rate increased by 6.6%, the abrasion resistance decreased by 40,000 cycles, the yellowing resistance decreased significantly, and the feel became sticky. This is mainly because the polypropylene oxide glycol used in Example 13 has lower strength, weaker hydrophobicity, and poorer hydrolysis and weather resistance compared to polytetrahydrofuran glycol or polycarbonate glycol. The polyurethane film of Example 14 had a water contact angle of 80°, a water absorption rate of 7.2%, a tensile strength of 26 MPa, an elongation at break of 600%, a Martindale abrasion resistance of 45,000 cycles, a mass loss of 0.065 g after a Taber abrasion resistance test (1000 rpm), and a yellowing grade of 4 after a yellowing resistance test. The prepared polyurethane film also had a smooth feel. Compared to Example 5, the water contact angle decreased by 6° and the water absorption rate increased by 1.0%, while the feel, tensile strength, and yellowing resistance did not change significantly. This is mainly because the organosilicon diol 4 used in Example 14 has a shorter branched chain structure, while the organosilicon diol 3 has a long alkyl side chain (-C). 10 H 21The structure of the polyurethane film has a lower surface energy, so the surface energy of the polyurethane film in Example 14 is slightly higher, the hydrophobicity is slightly worse, and the water absorption rate is slightly higher. However, due to the presence of Si-O, there is no significant difference in weather resistance and feel.

[0170] A comparison of Examples 1-12 with Comparative Examples 1-3 shows that the present invention, through the design of the raw materials for preparing the waterborne polyurethane resin emulsion, and further by using organosilicon polyols and controlling the amount of organosilicon polyols in the raw materials for preparing the waterborne polyurethane resin emulsion to 5-12 parts by weight, further improves the comprehensive performance of the waterborne polyurethane resin emulsion and the synthetic leather surface layer. With a small amount of organosilicon diol (1 part), the polyurethane film prepared in Comparative Example 1 has a water contact angle of 70°, a water absorption rate of 11.1%, a tensile strength of 22 MPa, an elongation at break of 500%, a Martindale abrasion resistance of 30,000 cycles, a mass loss of 0.088 g after the Taber abrasion resistance test (1000 rpm), and a yellowing grade of 3 after the yellowing resistance test. Furthermore, the prepared polyurethane film has a relatively rough feel. Compared with the unmodified Comparative Example 3, the overall performance shows no significant improvement. With a higher proportion of organosilicon glycol (30 parts), the polyurethane film of Comparative Example 2 had a water contact angle of 123°, a water absorption rate of 4.8%, a particle size of 210 nm, a tensile strength of 21 MPa, an elongation at break of 510%, a Martindale abrasion resistance of 60,000 cycles, a mass loss of 0.051 g after Taber abrasion resistance (1000 rpm) test, and a yellowing grade of 5 after yellowing resistance test. The prepared polyurethane film also had an ultra-smooth feel. In terms of overall performance, Comparative Example 2 showed significant improvement in hydrophobicity, abrasion resistance, and weather resistance. However, the higher proportion of organosilicon glycol resulted in more hydrophobic segments, which increased the emulsion particle size to 210 nm, leading to poor emulsion stability and cracking after the emulsion was prepared into a film.

[0171] Compared with Comparative Example 3, the water contact angles of the polyurethane films prepared from the waterborne polyurethane resin emulsions provided in Examples 1-3 increased to 96°, 98°, and 102°, respectively, indicating enhanced surface hydrophobicity; the water absorption rate decreased by approximately 60%, effectively improving the failure problem in humid environments. The Martindale abrasion resistance increased by over 20,000 cycles, and the Taber abrasion resistance mass loss significantly decreased, indicating a significant improvement in abrasion resistance; tensile strength and elongation slightly increased, indicating a flexible synergistic effect between the silicone segments and the polyurethane main chain. The yellowing grade improved from level 3 to level 4-5, indicating that the polyurethane film maintained a good appearance after UV irradiation. The polyurethane film prepared from the waterborne polyurethane resin emulsion provided in Comparative Example 1 had a slightly rough surface, but the polyurethane films prepared from the waterborne polyurethane resin emulsions provided in Examples 1-3 had a smooth or even silky feel, meeting the tactile requirements of high-grade synthetic leather surfaces. Meanwhile, the polyurethane film prepared from the waterborne polyurethane resin emulsion provided in Example 2 can be used for synthetic leather surface layers that require high abrasion resistance, such as sports shoe leather and work shoe leather. The polyurethane film prepared from the waterborne polyurethane resin emulsion provided in Example 2 can be used for automotive interior leather, outdoor leather, and high-grade synthetic leather with high weather resistance requirements.

[0172] A comparison of Examples 1 and 4-5 shows that the waterborne polyurethane resin prepared in Example 1 using a high molecular weight organosilicon diol exhibits high hydrophobicity, effectively reducing water absorption and possessing excellent abrasion resistance. It is suitable for high-end outdoor functional leather, high-end automotive interior leather, and other products requiring high hydrophobicity and a smooth feel. The waterborne polyurethane resin emulsion prepared in Example 5 using a low molecular weight organosilicon diol has a smaller particle size, decreasing from 85 nm to 77 nm, and the waterborne polyurethane resin emulsion is more stable. Compared to the polyurethane film prepared from the waterborne polyurethane resin emulsion provided in Comparative Example 3, the polyurethane film prepared from the waterborne polyurethane resin emulsion provided in Example 5 improves hydrophobicity (by 18° compared to Comparative Example 1) while maintaining a soft and smooth feel. However, the polyurethane resin prepared in Example 5 using a low molecular weight organosilicon diol has lower tensile strength, decreasing to 25 MPa; its yellowing resistance is improved by one grade compared to Comparative Example 1. Example 4: The waterborne polyurethane resin prepared using medium molecular weight organosilicon glycols is suitable for outdoor shoe leather and automotive interior leather requiring abrasion resistance, yellowing resistance, and a balanced hydrophobicity. Example 5: The waterborne polyurethane resin prepared using low molecular weight organosilicon glycols is suitable for applications requiring lower resin modulus and where cost is a concern, such as clothing leather.

[0173] In summary, this invention, through the design of raw materials for the preparation of waterborne polyurethane resin emulsions and by further utilizing organosilicon polyols and controlling their dosage within a specific range, has prepared waterborne polyurethane resin emulsions with good water resistance, good weather resistance, good abrasion resistance, and high transparency. The resulting synthetic leather prepared from these waterborne polyurethane resin emulsions has a smooth feel and high abrasion resistance.

[0174] The applicant declares that the detailed process flow of this invention is illustrated by the above embodiments, but this invention is not limited to the above detailed process flow, that is, it does not mean that this invention must rely on the above detailed process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, etc., all fall within the protection scope and disclosure scope of this invention.

Claims

1. A waterborne polyurethane resin emulsion, characterized in that, The raw materials for preparing the aqueous polyurethane resin emulsion include the following components in parts by weight: 50-100 parts of polymer polyol, 2-15 parts of organosilicon polyol, 15-40 parts of diisocyanate, 2-5 parts of hydrophilic chain extender, 0.2-1 parts of non-hydrophilic alcohol chain extender, 1-4 parts of neutralizer, and 1.5-6 parts of post-chain extender.

2. The aqueous polyurethane resin emulsion according to claim 1, characterized in that, The organosilicon polyols include organosilicon diols; Preferably, the organosilicon polyol comprises hydroxyl-terminated polydimethylsiloxane; Preferably, the number-average molecular weight of the organosilicon polyol is 2000-5000; Preferably, the organosilicon polyol has the structure shown in Formula I: Formula I; In this context, each R independently represents a C1-C10 alkylene group; n represents an integer between 0 and 30, and m represents an integer between 1 and 30; Preferably, the organosilicon polyol in the raw materials for preparing the waterborne polyurethane resin emulsion is 5-12 parts by weight.

3. The aqueous polyurethane resin emulsion according to claim 1 or 2, characterized in that, The polymeric polyol includes any one or a combination of at least two of polypropylene glycol, polytetrahydrofuran glycol or polycarbonate glycol, preferably polytetrahydrofuran glycol and / or polycarbonate glycol. Preferably, the number average molecular weight of the polymer polyol is 1000-3000, more preferably 1000-2500; Preferably, the diisocyanate comprises an aliphatic diisocyanate; Preferably, the aliphatic diisocyanate includes any one or a combination of at least two of isophorone diisocyanate, hexamethylene diisocyanate, or dicyclohexylmethane diisocyanate.

4. The aqueous polyurethane resin emulsion according to any one of claims 1-3, characterized in that, The hydrophilic chain extender includes any one or a combination of at least two of dimethylolpropionic acid, dimethylolbutyric acid, or sodium ethylenediamine ethanesulfonate. Preferably, the non-hydrophilic alcohol chain extender includes any one or a combination of at least two of 1,4-butanediol, 1,6-hexanediol, or trimethylolpropane; Preferably, the neutralizing agent includes any one or a combination of at least two of triethylamine, ammonia, N-methylmorpholine, N-ethylmorpholine, N-methyldiethanolamine, or sodium hydroxide; Preferably, the post-chain extender includes an amine chain extender; Preferably, the amine chain extender includes any one or a combination of at least two of ethylenediamine, propylenediamine, isofluranediamine, hydrazine hydrate, 2,4-toluenediamine, 2-methyl-1,5-pentanediamine, piperazine, or hexamethylenediamine.

5. The aqueous polyurethane resin emulsion according to any one of claims 1-4, characterized in that, The raw materials for preparing the waterborne polyurethane resin emulsion also include 0.01-0.2 parts by weight of catalyst; Preferably, the catalyst comprises any one or a combination of at least two of dibutyltin dilaurate, stannous octoate, tetramethylbutanediamine, or triethylenediamine; Preferably, the raw materials for preparing the waterborne polyurethane resin emulsion further include 50-200 parts by weight of organic solvent; Preferably, the organic solvent includes acetone and / or butanone; Preferably, the raw materials for preparing the waterborne polyurethane resin emulsion further include 100-300 parts by weight of water.

6. A method for preparing an aqueous polyurethane resin emulsion as described in any one of claims 1-5, characterized in that, The preparation method includes the following steps: (1) Prepolymerization reaction: Polymer polyol, organosilicon diol and diisocyanate undergo a prepolymerization reaction to obtain polyurethane prepolymer; (2) Introducing hydrophilic groups: The reaction system obtained in step (1) is mixed with hydrophilic chain extender, non-hydrophilic alcohol chain extender, optional catalyst and part of organic solvent, and reacted to obtain hydrophilic modified polyurethane prepolymer; (3) Neutralization reaction: The hydrophilic group modified polyurethane prepolymer obtained in step (2), the neutralizing agent and the remaining organic solvent are mixed and a neutralization reaction is carried out; (4) Emulsification: Add water to the reaction system obtained in step (3), emulsify, and disperse; (5) Chain extension reaction: The reaction system obtained in step (4) is mixed with the post-chain extender and a chain extension reaction is carried out to obtain the waterborne polyurethane resin emulsion.

7. The preparation method according to claim 6, characterized in that, The temperature of the prepolymerization reaction is 80-90℃; Preferably, the prepolymerization reaction takes 2-4 hours; Preferably, the prepolymerization reaction further includes a pretreatment step, wherein the pretreatment method includes vacuum dehydration of the polymer polyol and organosilicon diol. Preferably, the vacuum dehydration treatment is performed at a temperature of 90-120°C for a time of 20-60 minutes. Preferably, the reaction temperature in step (2) is 50-70°C; Preferably, the reaction time in step (2) is 2-4 h.

8. The preparation method according to claim 6 or 7, characterized in that, Step (3) before mixing also includes a step of cooling the hydrophilic group modified polyurethane prepolymer obtained in step (2) to below 40°C; Preferably, the temperature of the neutralization reaction in step (3) is 20-40°C; Preferably, the neutralization reaction in step (3) takes 1-5 minutes; Preferably, the dispersion time in step (4) is ≤3 min; Preferably, the stirring speed for dispersion in step (4) is 1500-1800 rpm; Preferably, the chain extension reaction in step (5) is carried out at a temperature of 20-40°C; Preferably, the chain extension reaction in step (5) takes 5-10 minutes; Preferably, the chain extension reaction in step (5) further includes a post-treatment step, wherein the post-treatment method includes: removing the organic solvent at -0.8 MPa ~ -0.1 MPa; Preferably, the solid content of the waterborne polyurethane resin emulsion is 30-45%; Preferably, the particle size of the aqueous polyurethane resin emulsion is 60-120 nm.

9. The preparation method according to any one of claims 6-8, characterized in that, The preparation method specifically includes the following steps: (1) Prepolymerization reaction: The polymer polyol and organosilicon diol are subjected to vacuum dehydration treatment at 90-120℃ for 20-60 min; The polymer polyol and organosilicon diol, which have undergone vacuum dehydration, are subjected to a prepolymerization reaction with diisocyanate at 80-90℃ for 2-4 h to obtain a polyurethane prepolymer. (2) Introducing hydrophilic groups: The reaction system obtained in step (1) is mixed with hydrophilic chain extender, optional catalyst and part of organic solvent, and reacted at 50-70℃ for 2-4 h to obtain hydrophilic modified polyurethane prepolymer; (3) Neutralization reaction: The hydrophilic group modified polyurethane prepolymer obtained in step (2), the neutralizing agent and the remaining organic solvent are mixed and neutralized at 20-40℃ for 1-5 min; (4) Emulsification: Add water to the reaction system obtained in step (3), emulsify, disperse, and disperse for ≤3 min; (5) Chain extension reaction: The reaction system obtained in step (4) is mixed with the post-chain extender and subjected to a chain extension reaction at 20-40℃ for 5-10 min. Then, the organic solvent and water are removed at -0.8 MPa ~ -0.1 MPa to obtain the waterborne polyurethane resin emulsion.

10. An application of the aqueous polyurethane resin emulsion as described in any one of claims 1-5, characterized in that, The aqueous polyurethane resin emulsion is used to prepare the surface layer of synthetic leather.

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