Preparation method and application of high-performance low-VOC polyurethane resin for leather finishing

Abstract

The present invention relates to the preparation of a high-performance low-VOC polyurethane resin for leather finishing, wherein polyether diol and isobornyl acrylate are uniformly mixed, isocyanate monomer and dibutyltin dilaurate are added to obtain a polyurethane prepolymer; manganese nitrate, naphthalene carboxylic acid, 5-hydroxy-1H-indazole-3-carboxylic acid and the like are used to obtain a high-performance filler; the high-performance filler, polyurethane prepolymer, polyurethane resin, sodium carboxymethyl cellulose and sodium tripolyphosphate are placed in a ball mill to obtain a high-performance low-VOC polyurethane resin. The high-performance low-VOC polyurethane resin of the present application can reduce the viscosity of polyurethane while improving the reaction activity of polyurethane segments and fillers, thereby reducing the situation of system viscosity increase caused by the use of fillers, and the non-polar cyclic functional group has good compatibility with the aromatic ring structure in the filler, which can improve the interface compatibility of the filler and polyurethane and promote the uniform distribution of the filler in the polyurethane.

Description

Technical Field

[0001] The invention relates to the technical field of leather making, and in particular to a preparation method and application of a high-performance, low-VOC polyurethane resin for leather finishing. Background Art

[0002] Mirror leather, also known as patent leather, is a common type of leather product. It is named because its surface has a mirror-like gloss, flatness, and brightness. The preparation process of patent leather is the same as that of conventional leather. It starts from raw leather and is prepared through processes such as soaking, liming, pickling, tanning, retanning, filling, and fatliquoring. However, the post-processing of patent leather is quite different from that of conventional leather. In the post-processing of patent leather, the degree of grinding is heavier than that of conventional leather, and there are more requirements for the leveling of resin. In addition, conventional leather is usually treated with middle-layer coating-top-layer coating-touch layer coating during post-processing, while the post-processing of patent leather is treated with middle-layer coating-painting. When painting, organic solvents are inevitably used. Although toxic and harmful solvents are no longer used in the processing of patent leather, and the process and control of painting are gradually improved, for patent leather, the small amount of solvent used in the painting process will cause the patent leather to carry a certain odor and VOC. In view of this, it is of certain significance to study the use of fillers with large specific surface area and non-polar functional groups in coatings to reduce odor and VOC. Summary of the invention

[0003] The present invention provides the preparation and application of a high-performance, low-VOC polyurethane resin for leather finishing, so as to overcome the problem that a small amount of solvent used in the painting process of the middle layer finishing will make the paint leather carry a certain odor and VOC, and realize the huge specific surface area and reaction activity of the high-performance filler to adsorb a variety of gas VOCs.

[0004] The present invention adopts the following technical solution:

[0005] A method for preparing a high-performance, low-VOC polyurethane resin for leather finishing comprises the following steps:

[0006] Step 1, preparation of small molecule polyurethane: 100 parts of polyether diol and 5-35 parts of isobornyl acrylate are mixed evenly, and then 200-500 parts of isocyanate monomer are slowly added. After mixing evenly, the temperature is raised to 50-75° C., and 2-5 parts of dibutyltin dilaurate are added dropwise within 1 hour. After keeping the temperature constant for 1-5 hours, the temperature is slowly lowered to room temperature to obtain a polyurethane prepolymer;

[0007] Step 2, preparation of high-performance filler: 50-80 parts of manganese nitrate, 20-35 parts of iron nitrate, 10-25 parts of aluminum nitrate, 10-30 parts of naphthalene carboxylic acid, 20-45 parts of 5-hydroxy-1H-indazole-3-carboxylic acid, and 0-20 parts of imidazole-4,5-dicarboxylic acid are dissolved in 3000-5000 parts of N,N-dimethylformamide, reacted at 85-110°C for 48-96h, then slowly cooled to room temperature, 1000 parts of N,N-dimethylformamide are added, the reaction is continued for 12h, and finally filtered, the filter residue is repeatedly washed with N,N-dimethylformamide, and vacuum dried to obtain a high-performance filler;

[0008] Step 3, preparation of high-performance low-VOC polyurethane resin: 10-100 parts of high-performance filler, 50-300 parts of polyurethane prepolymer, 1000 parts of polyurethane resin, 3-5 parts of sodium carboxymethyl cellulose, and 3-6 parts of sodium tripolyphosphate are placed in a ball mill, ball milled for 1 minute, stopped for 1 minute, and repeated 5 times to obtain a high-performance low-VOC polyurethane resin. Sodium carboxymethyl cellulose and sodium tripolymetaphosphate are used to adjust the viscosity of the system and the suspension of the filler in the system.

[0009] In a further improvement, the polyether diol is at least one of polyethylene glycol and polytetramethylene ether diol, wherein the molecular weight of the polyethylene glycol is 200 or 400 or 600 or 800, and the molecular weight of the polytetramethylene ether diol is 250 or 650.

[0010] In a further improvement, the isocyanate monomer contains at least diphenylmethane diisocyanate and may contain dicyclohexylmethane diisocyanate.

[0011] In a further improvement, the naphthalenecarboxylic acid-containing compound contains at least 1,4,5,8-naphthalenetetracarboxylic acid, and may contain 1,4-naphthalenedicarboxylic acid and 2,6-naphthalenedicarboxylic acid.

[0012] An application of a high-performance, low-VOC polyurethane resin for leather finishing, comprising at least a rolling slurry, a rolling coating slurry and a pouring paint slurry;

[0013] The rolling slurry includes the following components: 300-500 parts of acrylic resin, 200-300 parts of polyurethane resin, 50-100 parts of high-performance low-VOC polyurethane resin, 500-800 parts of composite resin, and 50-100 parts of oil wax filler;

[0014] The roller coating slurry includes the following components: 200-500 parts of polyurethane resin, 100-300 parts of acrylic resin, and 100-200 parts of high-performance low-VOC polyurethane resin;

[0015] The coating slurry comprises the following components: 200-300 parts of butyl acetate, 50-200 parts of high-performance low-VOC polyurethane resin, and 100-300 parts of polyurethane resin.

[0016] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages:

[0017] 1. The high-performance, low-VOC polyurethane resin of the present application is prepared by synthesizing some small molecule polyurethanes with non-polar cyclic functional groups (such as cyclohexyl). The small molecule polyurethanes have a structure similar to that of long-chain polyurethanes. While improving the reactivity of polyurethane segments with fillers, they can also reduce the viscosity of polyurethanes, thereby reducing the increase in system viscosity caused by the use of fillers. The non-polar cyclic functional groups have good compatibility with the aromatic ring structure in the fillers, thereby improving the interfacial compatibility between the fillers and polyurethanes and promoting the uniform distribution of the fillers in the polyurethanes.

[0018] 2. The high-performance filler has a huge specific surface area and reaction activity, which can absorb a variety of gas VOCs. For example, if 200g of high-performance filler is used, it can absorb 1.5m 3 The adsorption rates of 2000ppm acetone, benzene, toluene, xylene and 1,2-dichloroethane can all be ≥90%.

[0019] 3. High-performance fillers assisted by polyurethane film have extremely strong hydrolysis resistance. In the pH range of 3 to 11, the mass loss rate of the film in water is ≤2%. At the same time, it has extremely strong solvent resistance. In acetone and ethanol solvents, the mass loss rate is ≤5%.

[0020] 4. The high-performance filler has good dispersibility in the polyurethane matrix. With ethanol as solvent, the particle size of 2% high-performance filler / polyurethane composite material is 1000-2500nm, and the particle size distribution coefficient is 0.150-0.350.

[0021] 5. Leather coated with high-performance filler / polyurethane, VOC ≤ 100μg / g (QB / T 5249-2018), coating dry / wet rubbing resistance ≥ Level 4 (QB / T 2537-2001), abrasion resistance ≥ Level 4 (QB / T 2526-2005), room temperature flexing resistance ≥ 50,000 times (QB / T 2714-2018), dynamic waterproofing ≥ 20,000 times (SATRA TM34:1993). DETAILED DESCRIPTION

[0022] Embodiment 1:

[0023] A method for preparing a high-performance, low-VOC polyurethane resin for leather finishing comprises the following steps:

[0024] Step 1, preparation of small molecule polyurethane: take 100 parts of polyethylene glycol 600 and 15 parts of isobornyl acrylate and mix them evenly, then slowly add 220 parts of diphenylmethane diisocyanate, after mixing evenly, raise the temperature to 55°C, and add 3 parts of dibutyltin dilaurate dropwise within 1 hour, keep the temperature constant for 2 hours, then slowly reduce it to room temperature to obtain a polyurethane prepolymer.

[0025] Step 2, preparation of high-performance filler: 80 parts of manganese nitrate, 20 parts of ferric nitrate, 15 parts of aluminum nitrate, 30 parts of 1,4,5,8-naphthalenetetracarboxylic acid, 30 parts of 5-hydroxy-1H-indazole-3-carboxylic acid (CAS: 885518-94-5) are dissolved in 3000 parts of N,N-dimethylformamide, reacted at 85°C for 48 hours, then slowly cooled to room temperature, 1000 parts of N,N-dimethylformamide are added, and the reaction is continued for 12 hours, and finally filtered, the filter residue is repeatedly washed with N,N-dimethylformamide, and vacuum dried to obtain a high-performance filler.

[0026] Step 3, preparation of high-performance, low-VOC polyurethane resin: 10 parts of high-performance filler, 200 parts of polyurethane prepolymer, 1000 parts of polyurethane resin (PU62, Hongshengji), 3 parts of sodium carboxymethyl cellulose, and 5 parts of sodium tripolyphosphate are placed in a ball mill, ball milled for 1 minute, stopped for 1 minute, and repeated 5 times to obtain a high-performance, low-VOC polyurethane resin.

[0027] Embodiment 2:

[0028] A method for preparing a high-performance, low-VOC polyurethane resin for leather finishing comprises the following steps:

[0029] Step 1: Preparation of small molecule polyurethane: Take 100 parts of polytetramethylene glycol 250 and 30 parts of isobornyl acrylate and mix them evenly, then slowly add 200 parts of dicyclohexylmethane diisocyanate and 265 parts of diphenylmethane diisocyanate. After mixing evenly, raise the temperature to 70°C, and add 4 parts of dibutyltin dilaurate dropwise within 1 hour. After keeping the temperature constant for 4 hours, slowly reduce it to room temperature to obtain a polyurethane prepolymer.

[0030] Step 2: Preparation of high-performance filler: 72 parts of manganese nitrate, 28 parts of ferric nitrate, 20 parts of aluminum nitrate, 10 parts of 1,4-naphthalene dicarboxylic acid, 5 parts of 1,4,5,8-naphthalene tetracarboxylic acid, 25 parts of 5-hydroxy-1H-indazole-3-carboxylic acid (CAS: 885518-94-5), 10 parts of imidazole-4,5-dicarboxylic acid (CAS: 570-22-9) are dissolved in 4500 parts of N,N-dimethylformamide, react at 90°C for 72 hours, then slowly cool to room temperature, add 1000 parts of N,N-dimethylformamide, continue to react for 12 hours, and finally filter, repeatedly wash the filter residue with N,N-dimethylformamide, and vacuum dry to obtain a high-performance filler.

[0031] Step 3: Preparation of high-performance, low-VOC polyurethane resin: Take 20 parts of high-performance filler, 100 parts of polyurethane prepolymer, 1000 parts of polyurethane resin (PU62, Hongshengji), 4 parts of sodium carboxymethyl cellulose, and 6 parts of sodium tripolyphosphate and put them into a ball mill. Ball mill for 1 minute, stop for 1 minute, and repeat 5 times to obtain high-performance, low-VOC polyurethane resin.

[0032] Example 3

[0033] A method for preparing a high-performance, low-VOC polyurethane resin for leather finishing comprises the following steps:

[0034] Step 1: Preparation of small molecule polyurethane: Take 70 parts of polyethylene glycol 200, 30 parts of polytetramethylene glycol 650, and 20 parts of isobornyl acrylate and mix them evenly, then slowly add 100 parts of dicyclohexylmethane diisocyanate and 350 parts of diphenylmethane diisocyanate. After mixing evenly, increase the temperature to 63°C, and add 5 parts of dibutyltin dilaurate dropwise within 1 hour. After keeping the temperature constant for 5 hours, slowly reduce it to room temperature to obtain a polyurethane prepolymer.

[0035] Step 2: Preparation of high-performance filler: Take 55 parts of manganese nitrate, 30 parts of ferric nitrate, 25 parts of aluminum nitrate, 8 parts of 1,4-naphthalene dicarboxylic acid, 7 parts of 2,6-naphthalene dicarboxylic acid, 10 parts of 1,4,5,8-naphthalene tetracarboxylic acid), 42 parts of 5-hydroxy-1H-indazole-3-carboxylic acid (CAS: 885518-94-5), 18 parts of imidazole-4,5-dicarboxylic acid (CAS: 570-22-9) and dissolve them in 3500 parts of N,N-dimethylformamide, react at 105°C for 84 hours, then slowly cool to room temperature, add 1000 parts of N,N-dimethylformamide, continue to react for 12 hours, and finally filter, repeatedly wash the filter residue with N,N-dimethylformamide, and vacuum dry to obtain high-performance filler.

[0036] Step 3: Preparation of high-performance, low-VOC polyurethane resin: 100 parts of high-performance filler, 200 parts of polyurethane prepolymer, 1000 parts of polyurethane resin (PU62, Hongshengji), 5 parts of sodium carboxymethyl cellulose, and 3 parts of sodium tripolyphosphate are placed in a ball mill, ball milled for 1 minute, stopped for 1 minute, and repeated 5 times to obtain a high-performance, low-VOC polyurethane resin.

[0037] Embodiment 4:

[0038] An application of a high-performance, low-VOC polyurethane resin for leather finishing includes at least a rolling slurry, a rolling coating slurry and a pouring paint slurry, wherein the rolling slurry, the rolling coating slurry and the pouring paint slurry are added with the high-performance, low-VOC polyurethane resin prepared in Example 1.

[0039] The rolling slurry includes the following components: 150 parts of acrylic resin (1019, Paidao Chemical), 200 parts of acrylic resin (1079, Stahl), 80 parts of high-performance low-VOC polyurethane resin, 200 parts of polyurethane resin (2023, Paidao Chemical), 50 parts of polyurethane resin (2020, Paidao Chemical), 250 parts of composite resin (PU25, Zhiqi Trading), 300 parts of composite resin (78-823, Stahl), 100 parts of composite resin (SPI, Paidao Chemical), and 50 parts of oil wax filler (FD, Haowei Chemical).

[0040] The roller coating slurry includes the following components: 200 parts of polyurethane resin (8255, Stahl), 80 parts of polyurethane resin (8265, Stahl), 200 parts of acrylic resin (1079, Stahl), and 120 parts of high-performance low-VOC polyurethane resin.

[0041] The coating slurry includes the following components: 220 parts of butyl acetate, 80 parts of high-performance low-VOC polyurethane resin, 80 parts of polyurethane resin (PU62, Hongsheng base), and 120 parts of polyurethane resin (PU69, Hongsheng base).

[0042] Embodiment 5:

[0043] The application of the high-performance, low-VOC polyurethane resin for leather finishing in this embodiment is basically the same as that in Embodiment 4, except that the high-performance, low-VOC polyurethane resin prepared in Embodiment 2 is added to the rolling slurry, the rolling coating slurry and the pouring paint slurry.

[0044] Embodiment 6:

[0045] The application of the high-performance, low-VOC polyurethane resin for leather finishing in this embodiment is basically the same as that in Embodiment 6, except that the high-performance, low-VOC polyurethane resin prepared in Embodiment 3 is added to the rolling slurry, the rolling coating slurry and the pouring paint slurry.

[0046] Experimental testing

[0047] The high performance low VOC polyurethane resins obtained in Example 1, Example 2, and Example 3 were tested experimentally, and the experimental data obtained are shown in Table 1 below:

[0048] Table 1

[0049]

[0050] The finished leather obtained in Example 4, Example 5 and Example 6 was tested and the experimental data obtained are shown in Table 2 below:

[0051] Table 2

[0052]

[0053] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A method for preparing a high-performance, low-VOC polyurethane resin for leather finishing, characterized in that: The steps include: Step 1, take 100 parts of polyether diol and 5-35 parts of isobornyl acrylate and mix them evenly, then slowly add 200-500 parts of isocyanate monomer, after mixing evenly, raise the temperature to 50-75°C, and add 2-5 parts of dibutyltin dilaurate dropwise within 1 hour, keep the temperature constant for 1-5 hours, and then slowly reduce it to room temperature to obtain a polyurethane prepolymer; Step 2, dissolve 50-80 parts of manganese nitrate, 20-35 parts of ferric nitrate, 10-25 parts of aluminum nitrate, 10-30 parts of naphthalene carboxylic acid, 20-45 parts of 5-hydroxy-1H-indazole-3-carboxylic acid, and 0-20 parts of imidazole-4,5-dicarboxylic acid in 3000-5000 parts of N, N-dimethylformamide, react at 85-110° C. for 48-96 hours, then slowly cool to room temperature, add 1000 parts of N, N-dimethylformamide, continue to react for 12 hours, and finally filter, repeatedly wash the filter residue with N, N-dimethylformamide, and vacuum dry to obtain a high-performance filler; Step 3, put 10-100 parts of high-performance filler, 50-300 parts of polyurethane prepolymer, 1000 parts of polyurethane resin, 3-5 parts of sodium carboxymethyl cellulose, and 3-6 parts of sodium tripolyphosphate into a ball mill, ball mill for 1 minute, stop for 1 minute, and repeat 5 times to obtain a high-performance low-VOC polyurethane resin.

2. The method for preparing the high-performance, low-VOC polyurethane resin for leather finishing as claimed in claim 1, characterized in that: The polyether diol is at least one of polyethylene glycol and polytetramethylene ether glycol, wherein the molecular weight of polyethylene glycol is 200 or 400 or 600 or 800, and the molecular weight of polytetramethylene ether glycol is 250 or 650.

3. The method for preparing the high-performance, low-VOC polyurethane resin for leather finishing as claimed in claim 1, characterized in that: The isocyanate monomer contains at least diphenylmethane diisocyanate.

4. The method for preparing the high-performance, low-VOC polyurethane resin for leather finishing as claimed in claim 1, characterized in that: The naphthalene-containing carboxylic acid contains at least 1,4,5,8-naphthalenetetracarboxylic acid.

5. The use of a high-performance, low-VOC polyurethane resin for leather finishing as claimed in any one of claims 1 to 4, characterized in that: At least includes rolling slurry, rolling coating slurry and pouring painting slurry, and the rolling slurry includes the following components: 300-500 parts of acrylic resin, 200-300 parts of polyurethane resin, 50-100 parts of high-performance low-VOC polyurethane resin, 500-800 parts of composite resin, and 50-100 parts of oil wax filler; The roller coating slurry includes the following components: 200-500 parts of polyurethane resin, 100-300 parts of acrylic resin, and 100-200 parts of high-performance low-VOC polyurethane resin; The coating slurry includes the following components: 200-300 parts of butyl acetate, 50-200 parts of high-performance low-VOC polyurethane resin, and 100-300 parts of polyurethane resin.

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