Polyurethane resin for synthetic leather and preparation method and application thereof

Abstract

The present invention belongs to the technical field of synthetic leather, and specifically relates to a polyurethane resin for synthetic leather, and a preparation method and application thereof. In the present invention, soybean protein or soybean polypeptide is added to the synthesis of the polyurethane resin for synthetic leather, and the active groups contained in the soybean protein or soybean polypeptide are involved in the polyurethane reaction, and the excellent water solubility of the soybean protein and soybean polypeptide is utilized to generate a large number of dense pores during the solidification process of the resin, so that the leather can achieve a fuller and softer feel, and at the same time has excellent moisture permeability and air permeability. The wet synthetic leather prepared by the polyurethane resin for synthetic leather prepared by the present invention has a full and soft feel, fine folds, a high muscle rate (more than 55%), a peel strength higher than 25N / 2.5CM, and excellent water absorption.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic leather, and in particular relates to a polyurethane resin for synthetic leather and a preparation method and application thereof. Background Art

[0002] Due to the excellent properties of polyurethane synthetic leather, its application can be seen everywhere in human daily life and has penetrated into all aspects of human life, from household items to clothing and shoes, and car interiors. The application of polyurethane synthetic leather can be seen everywhere.

[0003] Traditional polyurethane resin for synthetic leather is made of polyglycol, chain extender and diisocyanate in a solvent system. Polyglycol is used as soft segment in the molecular structure, diisocyanate and chain extender are used as hard segment. The final molecular stacking structure is an aggregated structure with microphase separation of soft and hard segments. The synergistic effect of soft and hard segments gives it good ductility and flexibility. At the same time, using "H 2 The synthetic leather is solidified by the "O-DMF" replacement process, and a honeycomb-like porous structure is produced during the solidification. The porous structure makes the synthetic leather have a fleshy feel and fullness similar to natural leather, and the number and density of the porous structure directly affect the feel of the leather. If a polyurethane resin with a high-density, multi-cellular structure can be developed, it will bring more development directions for high-end synthetic leather, such as simulated leather clothing leather, protein-like clothing leather, and highly moisture-absorbent and breathable leather. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a polyurethane resin for synthetic leather and a preparation method and application thereof.

[0005] The first object of the present invention is to provide a method for preparing a polyurethane resin for synthetic leather, comprising the following steps: adding 99.2 to 100.8 parts of polyester polyol, 1.2 to 2.8 parts of soybean protein or soybean polypeptide, 83.5 parts of solvent, and 0.05 parts of antioxidant in a reaction kettle in sequence for stirring, and controlling the temperature in the reaction kettle to be 40 to 60°C; then adding 5.852 parts of diisocyanate, reacting under stirring, and controlling the temperature in the reaction kettle to be 70 to 80°C, after constant temperature for 1.5 to 2 hours, adding 52 parts of solvent, 4 parts of chain extender and 16.148 parts of diisocyanate, maintaining the temperature at 70 to 80°C, adding 156.5 parts of solvent for dilution as the viscosity increases until the product viscosity is 150 to 200 Pa.s / 25°C, terminating the reaction, and discharging after cooling to obtain a polyurethane resin for synthetic leather.

[0006] The solvent was added three times in a mass ratio of 1.6:1:3; the diisocyanate was added twice in a mass ratio of 1:2.76.

[0007] Furthermore, the preparation method of the polyurethane resin for synthetic leather comprises the following steps: adding 100 parts of polyester polyol, 2 parts of soybean protein or soybean polypeptide, 83.5 parts of solvent, and 0.05 parts of antioxidant in a reaction kettle in sequence for stirring, and controlling the temperature in the reaction kettle to 50°C, adding 5.852 parts of diisocyanate, reacting under stirring, and controlling the temperature in the reaction kettle to 75°C, after constant temperature for two hours, adding 52 parts of solvent, 4 parts of chain extender and 16.148 parts of diisocyanate, maintaining the temperature at 75°C, adding 156.5 parts of solvent for dilution as the viscosity increases until the product viscosity is 180 Pa.s / 25°C, terminating the reaction, and discharging after cooling to obtain the polyurethane resin for synthetic leather.

[0008] Furthermore, the polyester polyol includes the following components: ethylene glycol (EG), 1,4-butanediol (1.4-BG) and adipic acid (AA), and the molecular weight of the polyester polyol is 4000.

[0009] Furthermore, the soybean protein is soybean protein isolate, and the protein content of the soybean protein isolate is 99%.

[0010] Furthermore, the soybean polypeptide is a soybean protein hydrolyzate.

[0011] Furthermore, the solvent is N,N-dimethylformamide (DMF).

[0012] Furthermore, the antioxidant is antioxidant 1010.

[0013] Furthermore, the chain extender is ethylene glycol (EG) and / or 1,4-butanediol (1.4-BG).

[0014] Furthermore, the diisocyanate is diphenylmethane diisocyanate (MDI).

[0015] The second object of the present invention is to provide a polyurethane resin for synthetic leather, which is prepared using the above-mentioned method for preparing the polyurethane resin for synthetic leather.

[0016] The third object of the present invention is to provide a use of the polyurethane resin for synthetic leather as described above in the preparation of wet synthetic leather.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] (1) The present invention adds soybean protein or soybean polypeptide to the synthesis of polyurethane resin for synthetic leather, and by involving the active groups contained in the soybean protein or soybean polypeptide in the polyurethane reaction, a large number of dense pores are generated during the solidification process of the resin by utilizing the excellent water solubility of the soybean protein and soybean polypeptide, so that the leather has a fuller and softer feel and has excellent moisture permeability and air permeability;

[0019] (2) The wet synthetic leather prepared by the polyurethane resin for synthetic leather prepared by the present invention has a full and soft feel, fine folds, a high muscle rate (more than 55%), a peel strength higher than 25N / 2.5CM, and excellent water absorption. DETAILED DESCRIPTION

[0020] The principles and features of the present invention are described below in conjunction with examples. The examples are only used to explain the present invention and are not used to limit the scope of the present invention. The parts described in the specific implementation manner are parts by weight.

[0021] In a specific embodiment, the polyester polyols used are CMA-244-4000 of Huada Chemical Group Co., Ltd., the polyester polyols include ethylene glycol (EG), 1,4-butanediol (1.4-BG) and adipic acid (AA), and the molecular weight of the polyester polyol is 4000;

[0022] The soy protein used is YP926B from Shandong Yuwang Ecological Food Co., Ltd., and the soy protein is soy protein isolate, and the protein content of the soy protein isolate is 99%;

[0023] The soybean peptides used are all soybean small molecule peptides from Shandong Yuwang Ecological Food Co., Ltd., and the soybean peptides are the hydrolyzed products of soybean protein;

[0024] The solvent used was N,N-dimethylformamide (DMF), the antioxidant was antioxidant 1010, the chain extender was ethylene glycol (EG), and the diisocyanate was diphenylmethane diisocyanate (MDI).

[0025] Example 1

[0026] A preparation method of polyurethane resin for synthetic leather comprises the following steps: 100 parts of polyester polyol, 2 parts of soybean protein, 83.5 parts of solvent and 0.05 parts of antioxidant are sequentially added into a reactor for stirring, and the temperature in the reactor is controlled to be 50°C, 5.852 parts of diisocyanate are added, and the reaction is carried out under stirring, and the temperature in the reactor is controlled to be 75°C, after constant temperature for two hours, 52 parts of solvent, 4 parts of chain extender and 16.148 parts of diisocyanate are added, and the temperature is maintained at 75°C, and 156.5 parts of solvent are added for dilution as the viscosity increases until the product viscosity is 180 Pa.s / 25°C, the reaction is terminated, and the material is discharged after cooling to obtain the polyurethane resin for synthetic leather;

[0027] Note: The mass ratio of the polyester polyol, soybean protein, chain extender, diisocyanate, solvent and antioxidant is 1:0.02:0.04:0.22:2.92:0.0005; the mass ratio of the solvent added three times is 1.6:1:3; the mass ratio of the diisocyanate added twice is 1:2.76.

[0028] Example 2

[0029] The difference from Example 1 is that 2 parts of soybean protein are replaced by 2 parts of soybean peptides, that is, the mass ratio of the polyester polyol, soybean peptide, chain extender, diisocyanate, solvent, and antioxidant is 1:0.02:0.04:0.22:2.92:0.0005, and the other technical features are the same as those in Example 1.

[0030] Example 3

[0031] A preparation method of polyurethane resin for synthetic leather comprises the following steps: 99.2 parts of polyester polyol, 2.8 parts of soybean protein, 83.5 parts of solvent and 0.05 parts of antioxidant are sequentially added into a reactor for stirring, and the temperature in the reactor is controlled to be 40°C, 5.852 parts of diisocyanate are added, and the reaction is carried out under stirring, and the temperature in the reactor is controlled to be 70°C, after constant temperature for two hours, 52 parts of solvent, 4 parts of chain extender and 16.148 parts of diisocyanate are added, and the temperature is maintained at 70°C, and 156.5 parts of solvent are added for dilution as the viscosity increases until the product viscosity is 150 Pa.s / 25°C, the reaction is terminated, and the material is discharged after cooling to obtain the polyurethane resin for synthetic leather;

[0032] Note: The mass ratio of the polyester polyol, soybean protein, chain extender, diisocyanate, solvent and antioxidant is 0.992:0.028:0.04:0.22:2.92:0.0005; the mass ratio of the solvent added three times is 1.6:1:3; the mass ratio of the diisocyanate added twice is 1:2.76.

[0033] Example 4

[0034] The difference from Example 3 is that 2.8 parts of soybean protein are replaced by 2.8 parts of soybean polypeptide, that is, the mass ratio of the polyester polyol, soybean polypeptide, chain extender, diisocyanate, solvent, and antioxidant is 0.992:0.028:0.04:0.22:2.92:0.0005, and the remaining technical features are the same as those in Example 3.

[0035] Example 5

[0036] A preparation method of polyurethane resin for synthetic leather comprises the following steps: 100.8 parts of polyester polyol, 1.2 parts of soybean protein, 83.5 parts of solvent, and 0.05 parts of antioxidant are sequentially added into a reactor for stirring, and the temperature in the reactor is controlled to be 60°C, 5.852 parts of diisocyanate are added, and the reaction is carried out under stirring, and the temperature in the reactor is controlled to be 80°C, after constant temperature for 1.5 hours, 52 parts of solvent, 4 parts of chain extender and 16.148 parts of diisocyanate are added, and the temperature is maintained at 80°C, and 156.5 parts of solvent are added for dilution as the viscosity increases until the product viscosity is 200 Pa.s / 25°C, the reaction is terminated, and the material is discharged after cooling to obtain the polyurethane resin for synthetic leather;

[0037] Note: The mass ratio of the polyester polyol, soybean protein, chain extender, diisocyanate, solvent and antioxidant is 1.008:0.012:0.04:0.22:2.92:0.0005; the mass ratio of the solvent added three times is 1.6:1:3; the mass ratio of the diisocyanate added twice is 1:2.76.

[0038] Example 6

[0039] The difference from Example 5 is that 1.2 parts of soybean protein are replaced by 1.2 parts of soybean polypeptide, that is, the mass ratio of the polyester polyol, soybean polypeptide, chain extender, diisocyanate, solvent, and antioxidant is 1.008:0.012:0.04:0.22:2.92:0.0005, and the remaining technical features are the same as those in Example 5.

[0040] Comparative Example 1

[0041] The difference from Example 1 is that no soy protein is added, and 102 parts of the polyester polyol are added, that is, the mass ratio of the polyester polyol, chain extender, diisocyanate, solvent, and antioxidant is 1.02:0.04:0.22:2.92:0.0005, and the other technical features are the same as those in Example 1.

[0042] Comparative Example 2

[0043] The difference from Example 1 is that 101 parts of the polyester polyol are added and 1 part of the soy protein is added, that is, the mass ratio of the polyester polyol, soy protein, chain extender, diisocyanate, solvent, and antioxidant is 1.01:0.01:0.04:0.22:2.92:0.0005, and the other technical features are the same as those in Example 1.

[0044] Comparative Example 3

[0045] The difference from Example 1 is that 99 parts of the polyester polyol are added and 3 parts of the soy protein are added, that is, the mass ratio of the polyester polyol, soy protein, chain extender, diisocyanate, solvent, and antioxidant is 0.99:0.03:0.04:0.22:2.92:0.0005, and the other technical features are the same as those in Example 1.

[0046] Comparative Example 4

[0047] The difference from Example 2 is that 101 parts of the polyester polyol are added and 1 part of the soybean polypeptide is added, that is, the mass ratio of the polyester polyol, soybean polypeptide, chain extender, diisocyanate, solvent, and antioxidant is 1.01:0.01:0.04:0.22:2.92:0.0005, and the other technical features are the same as those in Example 2.

[0048] Comparative Example 5

[0049] The difference from Example 2 is that 99 parts of the polyester polyol are added and 3 parts of the soybean polypeptide are added, that is, the mass ratio of the polyester polyol, soybean polypeptide, chain extender, diisocyanate, solvent, and antioxidant is 0.99:0.03:0.04:0.22:2.92:0.0005, and the other technical features are the same as those in Example 2.

[0050] A process for preparing wet synthetic leather comprises the following steps:

[0051] S1, immersing the base fabric in a coagulation liquid for impregnation, wherein the coagulation liquid is a DMF aqueous solution, wherein the content of DMF is 20%;

[0052] S2, squeezing the base fabric impregnated with S1 on a squeezing roller, and then ironing the base fabric flat with an iron;

[0053] S3, coating the base fabric after ironing in S2 with a slurry having a coating thickness of 1 mm, wherein the slurry comprises polyurethane resin for synthetic leather, wood powder, color paste and DMF, and the weight ratio of the polyurethane resin for synthetic leather, wood powder, color paste and DMF is 100:35:6:120;

[0054] S4, immersing the base fabric coated with the slurry in S3 into a coagulation liquid (DMF aqueous solution with a DMF content of 20%) for coagulation for 10 minutes to obtain a pre-coagulated base fabric;

[0055] S5, washing and squeezing the pre-coagulated base fabric after coagulation in S4, immersing it in a water washing tank, and squeezing it on a squeezing roller, repeating ten times to obtain a semi-finished synthetic leather;

[0056] S6, drying the semi-finished synthetic leather after washing and extrusion in S5 in an oven at 110°C to obtain wet synthetic leather.

[0057] The polyurethane resins for synthetic leather prepared in Examples 1-6 and Comparative Examples 1-5 were used to prepare wet-process synthetic leather.

[0058] Performance testing method:

[0059] The following performance tests were performed on the wet synthetic leathers prepared using the polyurethane resins for synthetic leather of Examples 1-6 and Comparative Examples 1-5.

[0060] (1) Feel: Feeling by holding the device;

[0061] (2) Muscle-forming property test: Apply the prepared slurry on a glass plate with a thickness of 1 mm, then immerse it in a coagulation tank for coagulation. After washing and drying, test the thickness. Divide the thickness by the coating thickness of 1 mm to obtain the value.

[0062] (3) Folding: After the leather sample is rubbed through a rubbing machine, observe whether the leather surface texture is fine;

[0063] (4) Water absorption test: Use a dropper to drop a drop of water onto the leather surface and test the time it takes for the water drop to be completely absorbed by the leather surface;

[0064] (5) Peel strength test: Use an iron to apply a 2.5 cm wide adhesive strip to the leather surface, cut it and test it on a tensile testing machine.

[0065] The performance test data of the wet synthetic leather prepared using the polyurethane resin for synthetic leather of Examples 1-6 and Comparative Examples 1-5 are shown in Table 1.

[0066] Table 1 Performance test data table

[0067]

[0068] It can be seen from the performance test data of the wet-process synthetic leather in Table 1 that after a specific amount of soybean protein or soybean polypeptide is added to the preparation of the polyurethane resin for synthetic leather in the embodiments of the present invention, the obtained wet-process synthetic leather has a special leather-like feel style, is plump and soft, has delicate folds, and has excellent water absorption. At the same time, it can maintain good muscle-forming properties (more than 55%) and peel strength (higher than 25N / 2.5CM), and can be used for the production of high-end clothing leather, shoe leather, etc.

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a polyurethane resin for synthetic leather, characterized in that: The method comprises the following steps: adding 99.2-100.8 parts of polyester polyol, 1.2-2.8 parts of soybean protein or soybean polypeptide, 83.5 parts of solvent and 0.05 parts of antioxidant in parts by weight to a reactor for stirring, and controlling the temperature in the reactor to be 40-60°C; then adding 5.852 parts of diisocyanate, reacting under stirring, and controlling the temperature in the reactor to be 70-80°C, and after keeping the temperature constant for 1.5-2 hours, adding 52 parts of solvent, 4 parts of chain extender and 16.148 parts of diisocyanate, maintaining the temperature at 70-80°C, adding 156.5 parts of solvent for dilution as the viscosity increases, until the product viscosity is 150-200 Pa.s / 25°C, terminating the reaction, and discharging the material after cooling to obtain a polyurethane resin for synthetic leather; The polyester polyol comprises the following components: ethylene glycol, 1,4-butanediol and adipic acid, and the molecular weight of the polyester polyol is 4000.

2. The method for preparing a polyurethane resin for synthetic leather according to claim 1, characterized in that: The method comprises the following steps: adding 100 parts of polyester polyol, 2 parts of soybean protein or soybean polypeptide, 83.5 parts of solvent and 0.05 parts of antioxidant in a reaction kettle in sequence, stirring the mixture, controlling the temperature in the reaction kettle to be 50°C, adding 5.852 parts of diisocyanate, reacting the mixture under stirring, controlling the temperature in the reaction kettle to be 75°C, keeping the temperature constant for two hours, adding 52 parts of solvent, 4 parts of chain extender and 16.148 parts of diisocyanate, maintaining the temperature at 75°C, adding 156.5 parts of solvent to dilute the mixture as the viscosity increases, until the viscosity of the product reaches 180 Pa.s / 25°C, terminating the reaction, discharging the mixture after cooling, and obtaining a polyurethane resin for synthetic leather.

3. The method for preparing a polyurethane resin for synthetic leather according to claim 1, characterized in that: The soy protein is soy protein isolate, and the protein content of the soy protein isolate is 99%.

4. The method for preparing a polyurethane resin for synthetic leather according to claim 1, characterized in that: The soybean polypeptide is a soybean protein hydrolyzate.

5. The method for preparing a polyurethane resin for synthetic leather according to claim 1, characterized in that: The solvent is N,N-dimethylformamide.

6. The method for preparing a polyurethane resin for synthetic leather according to claim 1, characterized in that: The antioxidant is antioxidant 1010, and the chain extender is ethylene glycol and / or 1,4-butanediol.

7. The method for preparing a polyurethane resin for synthetic leather according to claim 1, characterized in that: The diisocyanate is diphenylmethane diisocyanate.

8. A polyurethane resin for synthetic leather, prepared by the method for preparing a polyurethane resin for synthetic leather according to any one of claims 1 to 7.

9. Use of the polyurethane resin for synthetic leather as claimed in claim 8 in the preparation of wet synthetic leather.

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