A polyurethane wet-process resin, its preparation method and application

Abstract

This invention relates to a polyurethane wet-process resin, its preparation method, and its applications. The raw materials for preparing the polyurethane wet-process resin, by weight, include 145-218 parts of polyester polyol, 13-21 parts of chain extender, 11-17 parts of hydroxyl-reactive organosilicon prepolymer, 0.1-0.2 parts of end-capping agent, 65-99 parts of isocyanate, and 544-816 parts of solvent. The polyester polyol includes adipic acid-1,4-butanediol-ethylene glycol polyester polyol and adipic acid-diethylene glycol polyester polyol. This invention combines polyester polyols with different structures and hydroxyl-reactive organosilicon prepolymers, and utilizes a "prepolymer viscosity-increasing method" for preparation. By optimizing the polyurethane chain segment structure and crystallization characteristics, the wet-process resin possesses characteristics such as good elasticity, soft hand feel, bright surface gloss, and good washability. The resulting synthetic leather maintains excellent vertical cell resilience and high-temperature laser engraving clarity, exhibiting good commercial value and application prospects.

Description

Technical Field

[0001] This invention relates to the field of polyurethane materials technology, and in particular to a polyurethane wet-process resin, its preparation method, and its application. Background Technology

[0002] Laser-etched label leather is the mainstream material in modern label manufacturing. Its core raw material is wet-process resin. The conventional preparation process is as follows: the prepared wet-process resin is introduced into water through a release cloth scraper to solidify, washed and dried to form a wet-process base, which is then laminated with dry-process fabric to make a label leather substrate, and finally laser-engraved at high temperature to obtain the finished product.

[0003] Currently, these resins on the market are mainly divided into two categories: soft and hard, both of which have obvious defects. Soft resins achieve the requirements of hand feel, water washing, and non-yellowing during laser engraving by adding a large amount of polyether-modified silicone oil softener and a small amount of antioxidant. However, the large amount of softener causes the base to slip during production and oil spots to appear on the surface, affecting production and appearance. Hard resins achieve non-yellowing during engraving by increasing their own modulus and add a small amount of hand feel aid to improve the hand feel. However, the excessively high modulus leads to unclear laser engraving patterns, poor batch stability, and the small amount of hand feel aid added makes the product prone to collapsing and difficult to clean during water washing.

[0004] In summary, existing wet-process resins cannot simultaneously achieve a full hand feel, high gloss, and non-yellowing and clear texture during laser engraving. This limits the development of downstream applications for laser-engraved trademark leather and makes it difficult to increase the added value of the product.

[0005] Therefore, how to provide a wet-process resin that can effectively solve the above-mentioned technical problems has become an urgent issue to be addressed. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a polyurethane wet-process resin, its preparation method, and its applications. By compounding polyester polyols with different structures and hydroxyl-reactive organosilicon prepolymers, the polyurethane chain structure is optimized, enabling the wet-process resin to possess characteristics such as good elasticity, soft hand feel, bright surface gloss, and good washability. The resulting synthetic leather can maintain excellent vertical cell resilience and high-temperature laser engraving clarity, exhibiting good commercial value and application prospects.

[0007] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, the present invention provides a polyurethane wet-process resin, wherein the raw materials for preparing the polyurethane wet-process resin include, by weight, 145-218 parts of polyester polyol, 13-21 parts of chain extender, 11-17 parts of hydroxyl-reactive organosilicon prepolymer, 0.1-0.2 parts of end-capping agent, 65-99 parts of isocyanate and 544-816 parts of solvent. The polyester polyols include adipic acid-1,4-butanediol-ethylene glycol polyester polyol and adipic acid-diethylene glycol polyester polyol.

[0008] Among them, 145-218 portions can be, for example, 145 portions, 150 portions, 155 portions, 160 portions, 165 portions, 170 portions, 175 portions, 180 portions, 185 portions, 190 portions, 195 portions, 200 portions, 205 portions, 215 portions, or 218 portions, etc.; 13-21 portions can be, for example, 13 portions, 14 portions, 15 portions, 16 portions, 17 portions, 18 portions, 19 portions, 20 portions, or 21 portions, etc.; 11-17 portions can be, for example, 11 portions, 12 portions, 13 portions, or 14 portions, etc. 15, 16, or 17 portions, etc.; 0.1-0.2 portions, for example, 0.1, 0.12, 0.14, 0.15, 0.16, 0.18, or 0.2 portions, etc.; 65-99 portions, for example, 65, 70, 75, 80, 85, 90, 95, or 99 portions, etc.; 544-816 portions, for example, 544, 550, 600, 650, 700, 750, 800, or 816 portions, etc.

[0009] This invention designs a polyurethane wet-process resin formulation, selecting polyester polyols with different structures for blending. The adipic acid-1,4-butanediol-ethylene glycol polyester polyol has a regular molecular chain, moderate crystallinity, and high rigidity, providing excellent peel strength, preventing product delamination, and optimizing the feel, laying the foundation for a full-bodied texture. The adipic acid-diethylene glycol polyester polyol has a high degree of molecular chain regularity and strong crystallinity, which can control the resin coagulation process, providing a uniform and stable coagulation rate, effectively avoiding defects such as rough surface and thickness deviations caused by uneven coagulation. It ensures the quality of product molding; at the same time, the introduction of hydroxyl-reactive organosilicon prepolymer can react with polyester polyol to form a stable cross-linked network, reduce molecular chain movement, and improve thickness retention. On the other hand, organosilicon segments fill the gaps between molecules, increase the bulkiness of the system, enhance the fullness and thickness, and the hydrophobic siloxane forms a dense protective film to block moisture, optimize water washing stability, and ensure high gloss and base flatness. Its high temperature resistance and anti-yellowing properties can inhibit degradation and yellowing during laser engraving, reduce heat damage, ensure clear texture, and solve technical pain points.

[0010] Preferably, the number average molecular weight of the adipic acid-1,4-butanediol-ethylene glycol polyester polyol is 3800-4200, for example, it can be 3800, 3900, 4000, 4100 or 4200.

[0011] Preferably, the number average molecular weight of the adipic acid-diethylene glycol polyester polyol is 2800-3200, for example, it can be 2800, 2900, 3000, 3100 or 3200.

[0012] Preferably, the mass ratio of adipic acid-1,4-butanediol-ethylene glycol polyester polyol to adipic acid-diethylene glycol polyester polyol is (15-20):1, for example, it can be 15:1, 16:1, 17:1, 18:1, 19:1 or 20:1, etc.

[0013] Preferably, the chain extender includes any one or a combination of at least two of ethylene glycol, 1,4-butanediol, or diethylene glycol, and more preferably ethylene glycol.

[0014] The preferred chain extender of this invention is ethylene glycol. Ethylene glycol, as a chain extender, increases the resin solidification speed, making the resin more uniform while ensuring an improved feel. Furthermore, increasing the amount of chain extender to improve the resin's modulus, temperature resistance, and gloss is easier to adjust than using chain extenders with side groups.

[0015] Preferably, the number average molecular weight of the hydroxyl-reactive organosilicon prepolymer is 3800-4200, for example, it can be 3800, 3900, 4000, 4100 or 4200.

[0016] In the preparation process of the polyurethane wet process resin of this invention, a specific ratio combination of adipic acid-1,4-butanediol-ethylene glycol polyester polyol with a number average molecular weight of 3800-4200, adipic acid-diethylene glycol polyester polyol with a number average molecular weight of 2800-3200, and hydroxyl-reactive organosilicon prepolymer with a number average molecular weight of 3800-4200 can optimize the film-forming properties, washability, and ability to form fine vertical pores of synthetic leather, while improving the hand feel of synthetic leather.

[0017] Preferably, the isocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, dimethyl diphenylmethane diisocyanate, or toluene diisocyanate.

[0018] Preferably, the capping agent comprises methanol.

[0019] Preferably, the solvent includes N,N-dimethylformamide.

[0020] Preferably, the raw materials for preparing the polyurethane wet-process resin further include 0.001-0.004 parts of inorganic acid and / or 20-30 parts of additives by weight.

[0021] Among them, 0.001-0.004 portions can be, for example, 0.001 portions, 0.002 portions, 0.003 portions, or 0.004 portions; 20-30 portions can be, for example, 20 portions, 22 portions, 24 portions, 25 portions, 26 portions, 28 portions, or 30 portions.

[0022] Preferably, the inorganic acid includes concentrated phosphoric acid.

[0023] Preferably, the additives include any one or a combination of at least two of the following: washing aids, stabilizers, or antioxidants.

[0024] Preferably, the detergent aid includes polyether polyol detergent aids and / or polysiloxane detergent aids.

[0025] Preferably, the stabilizer includes benzoic acid.

[0026] Preferably, the antioxidant includes hindered phenolic antioxidants.

[0027] In a second aspect, the present invention provides a method for preparing a polyurethane wet-process resin as described in the first aspect, the method comprising the following steps: (1) Mix adipic acid-diethylene glycol polyester polyol, a portion of an antioxidant, a portion of an inorganic acid, and a portion of a solvent, and then add a portion of isocyanate to carry out the reaction; (2) Add a portion of solvent and a portion of chain extender to the reaction system obtained in step (1) to carry out the reaction; (3) Add a portion of isocyanate to the reaction system obtained in step (2) to carry out the reaction; (4) Add a portion of isocyanate to the reaction system obtained in step (3) to carry out the reaction; (5) Add a portion of solvent and a portion of capping agent to the reaction system obtained in step (4) to carry out the reaction; (6) Add a portion of an optional stabilizer to the reaction system obtained in step (5) and mix to obtain a polyurethane wet-process resin intermediate; (7) Mix adipic acid-1,4-butanediol-ethylene glycol polyester polyol, hydroxyl reactive organosilicon prepolymer, the remaining antioxidant, the remaining inorganic acid and a portion of solvent, and then add a portion of isocyanate to react; (8) Add a portion of the solvent and the remaining chain extender to the reaction system obtained in step (7) and react; (9) Add a portion of isocyanate to the reaction system obtained in step (8) to carry out the reaction; (10) Add the remaining isocyanate to the reaction system obtained in step (9) and react; (11) Add the remaining solvent and the remaining capping agent to the reaction system obtained in step (10) and carry out the reaction; (12) Add the remaining, optionally stabilizer, the polyurethane wet process resin intermediate obtained in step (6) and optionally washing agent to the reaction system obtained in step (11) to obtain the polyurethane wet process resin.

[0028] In the preparation method provided by this invention, a polyurethane wet-process resin intermediate is prepared in advance using adipic acid-diethylene glycol polyester polyol as raw material. This intermediate is then further compounded with a product obtained from adipic acid-1,4-butanediol-ethylene glycol polyester polyol and hydroxyl-reactive organosilicon prepolymer. The preparation method of this invention employs a "prepolymer viscosity-increasing method" to precisely control the viscosity of the preparation system, thereby controlling the solidification speed of the polyurethane wet-process resin, improving water washability and the resin's feel. Firstly, the soft and hard segment blocks are more ordered, and the microphase separation is more reasonable, resulting in a more regular molecular structure, higher peel strength, and better heat resistance. During subsequent solidification, the pore structure is uniform, the pore walls are thicker, and the skeleton is stronger, resulting in a delicate surface, a firm feel, good elasticity, and good surface gloss.

[0029] Preferably, the antioxidant in step (1) optionally accounts for 8-14% of the total antioxidant, for example, it can be 8%, 9%, 10%, 11%, 12%, 13% or 14%, etc.

[0030] Preferably, the inorganic acid in step (1) may optionally account for 10-20% of the total inorganic acid, for example, it may be 10%, 12%, 14%, 15%, 16%, 18% or 20%, etc.

[0031] Preferably, the portion of solvent in step (1) accounts for 4-7% of the total solvent volume, for example, it can be 4%, 4.5%, 5%, 5.5%, 6%, 6.5% or 7%, etc.

[0032] Preferably, the isocyanate in step (1) accounts for 0.5-1.5% of the total isocyanate, for example, it can be 0.6%, 0.8%, 1%, 1.2%, 1.4% or 1.5%.

[0033] Preferably, the portion of solvent in step (2) accounts for 4-7% of the total solvent volume, for example, it can be 4%, 4.5%, 5%, 5.5%, 6%, 6.5% or 7%, etc.

[0034] Preferably, the chain extender in step (2) accounts for 2-3% of the total chain extender, for example, it can be 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8% or 3%, etc.

[0035] Preferably, the isocyanate in step (3) accounts for 1-3% of the total isocyanate, for example, it can be 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8% or 3%, etc.

[0036] Preferably, the isocyanate in step (4) accounts for 0.2-0.5% of the total isocyanate, for example, it can be 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45% or 0.5%.

[0037] Preferably, the portion of solvent in step (5) accounts for 10-15% of the total solvent volume, for example, it can be 10%, 11%, 12%, 13%, 14% or 15%, etc.

[0038] Preferably, the portion of the end-capping agent in step (5) accounts for 15-20% of the total end-capping agent, for example, it can be 15%, 16%, 17%, 18%, 19% or 20%, etc.

[0039] Preferably, the stabilizer in step (6) accounts for 15-20% of the total stabilizer, for example, it can be 15%, 16%, 17%, 18%, 19% or 20%, etc.

[0040] Preferably, the portion of solvent in step (7) accounts for 30-35% of the total solvent volume, for example, it can be 30%, 31%, 32%, 33%, 34% or 35%, etc.

[0041] Preferably, the isocyanate in step (7) accounts for 10-20% of the total isocyanate, for example, it can be 10%, 12%, 14%, 15%, 16%, 18% or 20%, etc.

[0042] Preferably, the portion of solvent in step (8) accounts for 25-30% of the total solvent, for example, it can be 25%, 26%, 27%, 28%, 29% or 30%, etc.

[0043] Preferably, the isocyanate in step (9) accounts for 65-75% of the total isocyanate, for example, it can be 65%, 66%, 68%, 70%, 72%, 74% or 75%, etc.

[0044] Preferably, after mixing in step (1), the mixture is heated to 40-50℃ (e.g., 40℃, 42℃, 44℃, 45℃, 46℃, 48℃ or 50℃, etc.) and kept at a constant temperature for 20-40 min (e.g., 20 min, 25 min, 30 min, 35 min or 40 min, etc.).

[0045] Preferably, the reaction temperature of the reaction in step (1) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0046] Preferably, the viscosity of the reaction system in step (1) at 25°C is 6-10 Pa·s, for example, it can be 6 Pa·s, 7 Pa·s, 8 Pa·s, 9 Pa·s or 10 Pa·s, etc.

[0047] Preferably, the temperature of the reaction in step (2) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0048] Preferably, the temperature of the reaction in step (3) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0049] Preferably, the temperature of the reaction in step (4) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0050] Preferably, after adding a portion of the solvent in step (5), the viscosity of the reaction system at 25°C is 10-16 Pa·s, for example, 10 Pa·s, 11 Pa·s, 12 Pa·s, 13 Pa·s, 14 Pa·s, 15 Pa·s or 16 Pa·s, etc., and the solid content of the reaction system is 29-31% (for example, 29%, 29.5%, 30%, 30.5% or 31%, etc.).

[0051] Preferably, the temperature of the reaction in step (5) is 60-70℃ (e.g., 60℃, 62℃, 64℃, 65℃, 66℃, 68℃ or 70℃, etc.), and the reaction time is 20-40 min (e.g., 20 min, 25 min, 30 min, 35 min or 40 min, etc.).

[0052] Preferably, the mixing temperature in step (6) is 50-60℃ (e.g., 50℃, 52℃, 54℃, 55℃, 56℃, 58℃ or 60℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0053] Preferably, in step (7), after mixing, the mixture is heated to 40-50°C (e.g., 40°C, 42°C, 44°C, 45°C, 46°C, 48°C, or 50°C) and kept at a constant temperature for 20-40 min (e.g., 20 min, 25 min, 30 min, 35 min, or 40 min).

[0054] Preferably, the reaction temperature of the reaction in step (7) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0055] Preferably, the viscosity of the reaction system in step (7) at 25°C is 6-10 Pa·s, for example, it can be 6 Pa·s, 7 Pa·s, 8 Pa·s, 9 Pa·s or 10 Pa·s, etc.

[0056] Preferably, the reaction temperature in step (8) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0057] Preferably, the temperature of the reaction in step (9) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0058] Preferably, the temperature of the reaction in step (10) is 70-75℃ (e.g., 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0059] Preferably, after adding a portion of the solvent in step (11), the viscosity of the reaction system at 25°C is 26-30 Pa·s (e.g., 26 Pa·s, 27 Pa·s, 28 Pa·s, 29 Pa·s or 30 Pa·s, etc.), and the solid content of the reaction system is 29-31% (e.g., 29%, 29.5%, 30%, 30.5% or 31%, etc.).

[0060] Preferably, the temperature of the reaction in step (11) is 60-70℃ (e.g., 60℃, 62℃, 64℃, 65℃, 66℃, 68℃ or 70℃, etc.), and the reaction time is 20-40 min (e.g., 20 min, 25 min, 30 min, 35 min or 40 min, etc.).

[0061] Preferably, the mixing temperature in step (12) is 50-60℃ (e.g., 50℃, 52℃, 54℃, 55℃, 56℃, 58℃ or 60℃, etc.), and the reaction time is 1-2 h (e.g., 1 h, 1.2 h, 1.4 h, 1.5 h, 1.6 h, 1.8 h or 2 h, etc.).

[0062] Thirdly, the present invention provides a synthetic leather comprising the polyurethane wet-process resin as described in the first aspect.

[0063] Compared with the prior art, the present invention has at least the following beneficial effects: (1) The present invention combines polyester polyols with different structures and hydroxyl-reactive organosilicon prepolymers, and combines the preparation method of "prepolymer viscosity enhancement method". By optimizing the polyurethane chain segment structure and crystallization characteristics, the wet process resin has the characteristics of good elasticity, soft hand feel, bright surface gloss and good water washability. The synthetic leather made can maintain excellent vertical cell resilience and high temperature laser engraving clarity.

[0064] (2) The polyurethane wet process resin provided by the present invention can be widely used in synthetic leather such as bags and shoes, which can significantly improve the surface smoothness and fullness of synthetic leather, while giving synthetic leather excellent peel strength and high temperature laser engraving clarity. Detailed Implementation

[0065] 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.

[0066] The specific information of the materials used in the following specific embodiments of the present invention is as follows: Adipic acid-1,4-butanediol-ethylene glycol polyester polyol (PE-17, total moles of diacid: total moles of diol = 1:1), number average molecular weight 4000; Adipic acid-1,4-butanediol-ethylene glycol polyester polyol (PE-16, total moles of diacid: total moles of diol = 1:1), number average molecular weight 2000; Adipic acid-diethylene glycol polyester polyol (PE-8, total moles of diacid: total moles of diol = 1:1.2), with a number average molecular weight of 3000; Adipic acid-diethylene glycol polyester polyol (PE-9, total moles of diacid: total moles of diol = 1:1.2), with a number average molecular weight of 2000; Hydroxyl reactive organosilicon prepolymer, Silok8815, with a number average molecular weight of 4000, was purchased from Guangzhou Silok New Materials Co., Ltd. Antioxidant 1330 was purchased from Taiwan Double Bond Chemical Co., Ltd. Polyether polyol detergent EP-3600, purchased from Shandong Lanxing Dongda Co., Ltd. Polysiloxane-based detergent additive, 8818F4, purchased from Guangzhou Sloco Polymer Co., Ltd.

[0067] Example 1 This embodiment provides a polyurethane wet-process resin and its preparation method. The raw materials for preparing the polyurethane wet-process resin include, by weight, 142.8 parts of adipic acid-1,4-butanediol-ethylene glycol polyester polyol (PE-17), 8 parts of adipic acid-diethylene glycol polyester polyol (PE-8), 14.1 parts of hydroxyl-reactive organosilicon prepolymer, 73.4 parts of diphenylmethane diisocyanate (MDI), 15.42 parts of ethylene glycol (EG), 0.29 parts of antioxidant (ROX-13TP), 0.0018 parts of concentrated phosphoric acid, 0.15 parts of methanol, 0.25 parts of benzoic acid, 12.1 parts of polysiloxane-based washing aid (8818F4), 12.1 parts of polyether polyol-based washing aid (EP-3600), and 680 parts of N,N-dimethylformamide (DMF).

[0068] The preparation method includes: (1) Mix adipic acid-diethylene glycol polyester polyol (PE-8), antioxidant (ROX-13TP) at 11% of the total mass, concentrated phosphoric acid at 16.67% of the total mass, and DMF at 5.21% of the total mass. Heat the system to 45°C and maintain for 30 min. Then add MDI at 0.9% of the total mass and react at 73°C for 1.5 h. The viscosity of the reaction system is 6-10 Pa·s / 25°C. (2) Add 5.49% DMF and 2.69% ethylene glycol by mass to the reaction system obtained in step (1) and react at 73°C for 1.5 h; (3) Add 1.9% of the total mass of MDI to the reaction system obtained in step (2) and react at 73°C for 1.5 h; (4) Add 0.34% of the total mass of MDI to the reaction system obtained in step (3) and react at 73°C for 1.5 h; (5) Add 12.19% of the total mass of DMF to the reaction system obtained in step (4) to make the viscosity of the reaction system 10-16 Pa·s / 25℃ and the solid content of the reaction system 29-31%. Then add 17% of the total mass of methanol and stir at 65℃ for 30 min. Then cool the system to 55℃. (6) Add 18.6% of the total mass of benzoic acid to the reaction system obtained in step (5), mix and stir for 1.5 h to obtain a polyurethane wet process resin intermediate; (7) Mix adipic acid-1,4-butanediol-ethylene glycol polyester polyol (PE-17), hydroxyl reactive organosilicon prepolymer, the remaining antioxidant (ROX-13TP), the remaining concentrated phosphoric acid and DMF accounting for 32.39% of the total mass of DMF, and then add MDI accounting for 14.55% of the total mass of MDI and react at 73°C for 1.5 h. The viscosity of the reaction system is 6-10 Pa·s / 25°C. (8) Add 27.71% of the total mass of DMF and the remaining ethylene glycol to the reaction system obtained in step (7) and react at 73°C for 1.5 h; (9) Add 71.58% of the total mass of MDI to the reaction system obtained in step (8) and react at 73°C for 1.5 h; (10) Add the remaining MDI to the reaction system obtained in step (9) and react at 73°C for 1.5 h; (11) Add the remaining DMF to the reaction system obtained in step (10) so that the viscosity of the reaction system is 26-30 Pa·s / 25℃ and the solid content of the reaction system is 29-31%. The remaining methanol is stirred at 65℃ for 30 min and then the system is cooled to 55℃. (12) Add the remaining benzoic acid, the polyurethane wet process resin intermediate obtained in step (6), the polysiloxane-based water-washing agent (8818F4), and the polyether polyol-based water-washing agent (EP-3600) to the reaction system obtained in step (11), mix and stir for 1.5 h to obtain the polyurethane wet process resin.

[0069] Examples 2-9 and Comparative Examples 1-4 Examples 2-9 and Comparative Examples 1-4 respectively provide a polyurethane wet-process resin and its preparation method. The difference from Example 1 is that the types and / or amounts of the components are different, as shown in Table 1-2 (the amounts of each component in Table 1-2 are all by weight). "--" indicates that the component was not added. All other aspects are the same as in Example 1.

[0070] Table 1 Table 2 Application Examples 1-9 and Comparative Examples 1-4 Application Examples 1-9 and Comparative Applications 1-4 respectively provide a synthetic leather and a method for preparing the same, wherein the synthetic leather is prepared by the following method: Take 100 g of the polyurethane wet-process resin provided in Examples 1-9 and Comparative Examples 1-4, 1 g of oily black paste (purchased from Jiangxi Sangao Polymer Materials Co., Ltd.), and 60 g of DMF, respectively, mix and stir at high speed at 3000 r / min until uniform, and then let stand to remove bubbles to obtain the slurry for later use. The release fabric for leather is soaked in a 50 wt% DMF aqueous solution to remove surface impurities, then pressed with a water press and ironed until semi-dry. Finally, a 0.2 mm thick feeler gauge is placed on the back of the release fabric. Pour a small amount of the above slurry onto the surface of the release fabric for leather and scrape it to maintain a wet film thickness of 0.2 mm. Then place it in water to solidify for 10 minutes, and then wash it with water and dry it at 110°C to obtain a wet-process base. The obtained wet-process base is then bonded to a dry-process fabric with a thickness of 15 mils (150 μm) to obtain the synthetic leather.

[0071] Test methods (1) Thickness: The wet-process base provided in the application example and comparative application example is spread out at a fixed caliper of 100 mils and placed in a coagulation tank containing 20 wt% DMF aqueous solution for 15 min. The thickness after coagulation is better if it reaches 0.3 mm or more, and worse if it is less than 0.1 mm. (2) Cell shape: Cut open the synthetic leather provided in the application example and comparative application example. A cell layer with fine and uniform vertical cells is better; a cell layer with fine and uneven elliptical cells is worse. (3) Feel: The synthetic leather provided in the application examples and comparative application examples is considered superior if it feels full and fleshy; it is considered inferior if it does not feel full and fleshy. (4) Heat resistance and anti-yellowing performance: The synthetic leather surface provided by the application examples and comparative application examples that have undergone high-temperature laser engraving (instantaneous temperature of 250-300℃) does not turn yellow and the texture is clear and full. If the trademark leather surface turns yellow and the texture is not clear and full, it is poor. (5) Water washability: The surface of the wet-process base provided in the application example and comparative application example is good if it is smooth after being squeezed 15 times by a water washing roller (pressure 0.5Mpa, water temperature 25℃); the surface is poor if it is uneven.

[0072] The test results are shown in Table 3 below: Table 3 The test results show that: (1) As can be seen from Application Examples 1 to 9, the present invention combines polyester polyols with different structures and hydroxyl-reactive organosilicon prepolymers, and combines the preparation method of "prepolymer viscosity enhancement method". By optimizing the polyurethane chain segment structure and crystallization characteristics, the wet-process base film prepared has good film-forming state, smooth surface, uniform pores and full texture. The synthetic leather finished product has excellent performance in core indicators such as hand feel, water resistance, heat resistance and anti-yellowing properties, and the overall use effect is good.

[0073] (2) As can be seen from Application Example 1 and Application Examples 4-5 and Comparative Application Examples 1-4, by further limiting the amount of hydroxyl reactive organosilicon prepolymer, the present invention can achieve better technical effects of improving surface gloss and preventing yellowing during high-temperature laser engraving.

[0074] (3) As can be seen from Application Examples 1 and 6-7, by selecting adipic acid-1,4-butanediol-ethylene glycol polyester polyol with a number average molecular weight of 3800-4200, the present invention can achieve better water-washing resistance and form a fine vertical cell structure in the product, while also helping to enhance the fullness and thickness of synthetic leather products. By selecting adipic acid-diethylene glycol polyester polyol with a number average molecular weight of 2800-3200, the present invention can obtain excellent wet-process base film-forming properties and water-washing resistance.

[0075] (4) As can be seen from Application Example 1 and Application Examples 8-9, the present invention can improve the resin coagulation speed by using ethylene glycol as a chain extender, making the wet resin more uniform and improving the feel of synthetic leather.

[0076] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A polyurethane wet-process resin, characterized in that, The raw materials for preparing the polyurethane wet-process resin include, by weight, 145-218 parts of polyester polyol, 13-21 parts of chain extender, 11-17 parts of hydroxyl-reactive organosilicon prepolymer, 0.1-0.2 parts of end-capping agent, 65-99 parts of isocyanate, and 544-816 parts of solvent. The polyester polyols include adipic acid-1,4-butanediol-ethylene glycol polyester polyol and adipic acid-diethylene glycol polyester polyol.

2. The polyurethane wet-process resin according to claim 1, characterized in that, The number-average molecular weight of the adipic acid-1,4-butanediol-ethylene glycol polyester polyol is 3800-4200. Preferably, the number average molecular weight of the adipic acid-diethylene glycol polyester polyol is 2800-3200; Preferably, the mass ratio of adipic acid-1,4-butanediol-ethylene glycol polyester polyol to adipic acid-diethylene glycol polyester polyol is (15-20):

1.

3. The polyurethane wet-process resin according to claim 1 or 2, characterized in that, The chain extender includes any one or a combination of at least two of ethylene glycol, 1,4-butanediol, or diethylene glycol, preferably ethylene glycol.

4. The polyurethane wet-process resin according to any one of claims 1-3, characterized in that, The number-average molecular weight of the hydroxyl-reactive organosilicon prepolymer is 3800-4200.

5. The polyurethane wet-process resin according to any one of claims 1-4, characterized in that, The isocyanate includes any one or a combination of at least two of diphenylmethane diisocyanate, dimethyl diphenylmethane diisocyanate, or toluene diisocyanate; Preferably, the capping agent comprises methanol; Preferably, the solvent includes N,N-dimethylformamide.

6. The polyurethane wet-process resin according to any one of claims 1-5, characterized in that, The raw materials for preparing the polyurethane wet-process resin also include 0.001-0.004 parts of inorganic acid and / or 20-30 parts of additives by weight.

7. The polyurethane wet-process resin according to claim 6, characterized in that, The inorganic acid includes concentrated phosphoric acid; Preferably, the auxiliary agent includes any one or a combination of at least two of the following: a washing aid, a stabilizer, or an antioxidant; Preferably, the detergent aid includes polyether polyol detergent aids and / or polysiloxane detergent aids; Preferably, the stabilizer includes benzoic acid; Preferably, the antioxidant includes hindered phenolic antioxidants.

8. A method for preparing a polyurethane wet-process resin as described in any one of claims 1-7, characterized in that, The preparation method includes the following steps: (1) Mix adipic acid-diethylene glycol polyester polyol, a portion of an antioxidant, a portion of an inorganic acid, and a portion of a solvent, and then add a portion of isocyanate to carry out the reaction; (2) Add a portion of solvent and a portion of chain extender to the reaction system obtained in step (1) to carry out the reaction; (3) Add a portion of isocyanate to the reaction system obtained in step (2) to carry out the reaction; (4) Add a portion of isocyanate to the reaction system obtained in step (3) to carry out the reaction; (5) Add a portion of solvent and a portion of capping agent to the reaction system obtained in step (4) to carry out the reaction; (6) Add a portion of an optional stabilizer to the reaction system obtained in step (5) and mix to obtain a polyurethane wet-process resin intermediate; (7) Mix adipic acid-1,4-butanediol-ethylene glycol polyester polyol, hydroxyl reactive organosilicon prepolymer, the remaining antioxidant, the remaining inorganic acid and a portion of solvent, and then add a portion of isocyanate to react; (8) Add a portion of the solvent and the remaining chain extender to the reaction system obtained in step (7) and react; (9) Add a portion of isocyanate to the reaction system obtained in step (8) to carry out the reaction; (10) Add the remaining isocyanate to the reaction system obtained in step (9) and react; (11) Add the remaining solvent and the remaining capping agent to the reaction system obtained in step (10) and carry out the reaction; (12) Add the remaining, optionally stabilizer, the polyurethane wet process resin intermediate obtained in step (6) and optionally washing agent to the reaction system obtained in step (11) to obtain the polyurethane wet process resin.

9. The method for preparing polyurethane wet-process resin according to claim 8, characterized in that, The antioxidants mentioned in step (1) optionally constitute 8-14% of the total antioxidants; Preferably, the inorganic acid in step (1) optionally accounts for 10-20% of the total inorganic acid; Preferably, the solvent in step (1) accounts for 4-7% of the total solvent volume; Preferably, the isocyanate in step (1) accounts for 0.5-1.5% of the total isocyanate; Preferably, the solvent in step (2) accounts for 4-7% of the total solvent volume; Preferably, the chain extender in step (2) accounts for 2-3% of the total chain extender; Preferably, the isocyanate in step (3) accounts for 1-3% of the total isocyanate; Preferably, the isocyanate in step (4) accounts for 0.2-0.5% of the total isocyanate; Preferably, the solvent in step (5) accounts for 10-15% of the total solvent volume; Preferably, the portion of the end-capping agent described in step (5) accounts for 15-20% of the total end-capping agent; Preferably, the stabilizer in step (6) accounts for 15-20% of the total stabilizer. Preferably, the solvent in step (7) accounts for 30-35% of the total solvent volume; Preferably, the isocyanate in step (7) accounts for 10-20% of the total isocyanate; Preferably, the solvent in step (8) accounts for 25-30% of the total solvent volume; Preferably, the isocyanate in step (9) accounts for 65-75% of the total isocyanate; Preferably, after mixing in step (1), the mixture is heated to 40-50°C and kept at that temperature for 20-40 min. Preferably, the reaction temperature in step (1) is 70-75℃ and the reaction time is 1-2 h; Preferably, the viscosity of the reaction system in step (1) at 25°C is 6-10 Pa·s; Preferably, the reaction temperature in step (2) is 70-75℃, and the reaction time is 1-2 h; Preferably, the reaction temperature in step (3) is 70-75℃, and the reaction time is 1-2 h; Preferably, the reaction temperature in step (4) is 70-75℃, and the reaction time is 1-2 h; Preferably, after adding a portion of the solvent in step (5), the viscosity of the reaction system at 25°C is 10-16 Pa·s, and the solid content of the reaction system is 29-31%. Preferably, the reaction temperature in step (5) is 60-70°C and the reaction time is 20-40 min; Preferably, the mixing temperature in step (6) is 50-60°C, and the reaction time is 1-2 h; Preferably, after mixing in step (7), the mixture is heated to 40-50°C and kept at that temperature for 20-40 minutes. Preferably, the reaction temperature in step (7) is 70-75℃ and the reaction time is 1-2 h; Preferably, the viscosity of the reaction system in step (7) at 25°C is 6-10 Pa·s; Preferably, the reaction temperature in step (8) is 70-75°C, and the reaction time is 1-2 h; Preferably, the reaction temperature in step (9) is 70-75°C and the reaction time is 1-2 h; Preferably, the reaction temperature in step (10) is 70-75°C and the reaction time is 1-2 hours; Preferably, after adding a portion of the solvent in step (11), the viscosity of the reaction system at 25°C is 26-30 Pa·s, and the solid content of the reaction system is 29-31%. Preferably, the reaction temperature in step (11) is 60-70°C and the reaction time is 20-40 min; Preferably, the mixing temperature in step (12) is 50-60°C and the reaction time is 1-2 h.

10. A synthetic leather, characterized in that, The synthetic leather comprises the polyurethane wet-process resin as described in any one of claims 1-7.

Images