A synthetic leather based on recyclable bio-based polyurethane resin and its preparation method

Abstract

The present invention discloses a synthetic leather based on recyclable bio-based polyurethane resin and a preparation method thereof. In the process of preparing this synthetic leather, recyclable bio-based polyurethane resin and other materials are respectively made into impregnating materials for impregnation, knife coating materials for knife coating, and back coating materials for back coating according to different formulas, which can enable the finally prepared synthetic leather to not only have a high recycling rate but also have high hydrolysis resistance.

Description

Technical Field

[0001] The present invention relates to the field of synthetic leather manufacturing, and particularly to a synthetic leather based on recyclable bio-based polyurethane resin and a preparation method thereof. Background Art

[0002] With the development of society, people increasingly pay attention to concepts such as recyclability. In the field of synthetic leather, in order to ensure hydrolysis resistance, traditional synthetic leather usually uses a hydrolysis-resistant polyurethane resin (cross-linked structure) synthesized from ordinary petroleum-based materials during its manufacturing process to enable the synthetic leather to have better hydrolysis resistance. However, the recycling rate of this kind of polyurethane resin is less than 10%. For this reason, in the prior art, there has emerged a synthetic leather manufactured using recyclable bio-based polyurethane resin. This kind of polyurethane resin has a high biodegradation rate and can be recycled through adjusting specific temperature, light intensity, etc., with a recycling rate ≥ 90%. However, the hydrolysis resistance of the synthetic leather manufactured using recyclable bio-based polyurethane resin is poor and it is difficult to reach the level of traditional synthetic leather. Summary of the Invention

[0003] The purpose of the present invention is to overcome the above-mentioned defects or problems in the background art and provide a synthetic leather based on recyclable bio-based polyurethane resin and a preparation method thereof, which have good hydrolysis resistance and a high recycling rate.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] The first technical solution relates to a synthetic leather based on recyclable bio-based polyurethane resin, which is prepared by impregnating a base fabric, pre-solidifying, knife coating, solidifying, first water washing, back coating, second water washing, and drying. Among them, by mass, the impregnating material used for impregnation is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 540 - 560 parts of dimethylformamide, 14 - 16 parts of tear-resistant resin, and 3 - 20 parts of color paste, and then controlling the viscosity to be less than or equal to 30 CPS and the temperature to be at room temperature; by mass, the knife coating material used for knife coating is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 35 - 45 parts of dimethylformamide, 0.5 - 1.5 parts of non-ionic surfactant, 0.5 - 1 part of fluorine-free water-resistant additive, and 1 - 3 parts of color paste, then degassing, and controlling the viscosity to be 13000 - 15000 CPS and the temperature to be 32 - 36 °C; by mass, the back coating material used for back coating is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 340 - 360 parts of dimethylformamide, 1 - 2 parts of fluorine-free water-resistant additive, and 3 - 20 parts of color paste, and then controlling the viscosity to be 100 - 140 CPS and the temperature to be at room temperature.

[0006] The second technical solution is based on the first technical solution. Among them, the optimal ratio of the impregnating material is 100 parts of recyclable bio-based polyurethane resin, 550 parts of dimethylformamide, 15 parts of tear-resistant resin, and 8 parts of color paste; the optimal ratio of the knife coating material is 100 parts of recyclable bio-based polyurethane resin, 40 parts of dimethylformamide, 1 part of non-ionic surfactant, 1 part of fluorine-free water-resistant additive, and 3 parts of color paste; the optimal ratio of the back coating material is 100 parts of recyclable bio-based polyurethane resin, 350 parts of dimethylformamide, 2 parts of fluorine-free water-resistant additive, and 12 parts of color paste.

[0007] The third technical solution is based on the first technical solution. Among them, the base fabric is bio-based fully polyester non-woven fabric.

[0008] The fourth technical solution is based on the first technical solution. Among them, the gap and coating amount of the coating obtained by knife coating on the base fabric are 205 - 215 filaments and 1.15 - 1.25 kg / y respectively.

[0009] The fifth technical solution is based on any one of the technical solutions 1 - 4. Among them, the physical property indexes of the recyclable bio-based polyurethane resin are as follows: the solid content is 30%, the hundred percent modulus is 60 - 80, the tensile strength is greater than 45 MPa, the elongation at break is greater than or equal to 500%, and the viscosity range is 180,000 - 250,000.

[0010] The sixth technical solution relates to a preparation method of a synthetic leather based on recyclable bio-based polyurethane resin as described in any one of the technical solutions 1 - 5. Among them, it includes the following steps:

[0011] S1: Feed the base fabric into the impregnating material for impregnation, and the impregnation pressure is 5 - 5.5 kg;

[0012] S2: Feed the impregnated base fabric into the pre-curing liquid for pre-curing, the pre-curing pressure is 5 - 5.5 kg, and the sugar content of the pre-curing liquid is 28 - 32%;

[0013] S3: Iron the pre-cured base fabric flat, and apply the knife coating material onto the base fabric by means of knife coating through a coating table;

[0014] S4: Feed the knife-coated base fabric into the curing liquid for curing, the sugar content of the curing liquid is 18 - 22%, and the temperature is 28 - 32 °C;

[0015] S5: Conduct the first water washing on the cured base fabric, and the sugar content of the washing liquid used for the first water washing is 20 - 22%, and the temperature is normal temperature;

[0016] S6: Feed the base fabric after the first water washing into a back coating machine for back coating;

[0017] S7: The base fabric after back coating is subjected to a second water wash, which is carried out in two steps. The temperature of the water wash liquid in the first step is normal temperature and the sugar content is 0%; the temperature of the water wash liquid in the second step is 60 - 80°C and the sugar content is 0%.

[0018] S8: The base fabric after the second water wash is pre - ironed by an ironing roller and then sent into an oven for drying.

[0019] The seventh technical solution is based on the sixth technical solution. When the base fabric after knife coating is sent into the coagulating liquid for coagulation, the base fabric after knife coating forms at least three - layer folds in the coagulating liquid.

[0020] The eighth technical solution is based on the seventh technical solution. The base fabric after knife coating forms five - layer folds in the coagulating liquid.

[0021] The ninth technical solution is based on the sixth technical solution. The oven is divided into five groups. The temperature of the first - group oven is 150°C, the temperature of the second - to - fourth - group ovens is 160°C, and the temperature of the fifth - group oven is 140°C.

[0022] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. Although the synthetic leather made of recyclable bio - based polyurethane resin in the prior art has a high recycling rate, the reason for its poor hydrolysis resistance is that the recyclable bio - based polyurethane resin used in its manufacturing process is not re - treated. Therefore, although the recyclable bio - based polyurethane resin has a high recycling rate, due to the diversity of the resin network structure and the sensitivity of the isocyanate in its synthetic materials, the hydrolysis resistance of the synthetic leather prepared is poor.

[0024] Therefore, in this application, the recyclable bio - based polyurethane resin is not directly used as the impregnating material, knife coating material, and back coating material. Instead, it is re - treated and mixed with other materials as raw materials to obtain the impregnating material, knife coating material, and back coating material adopted in this technical solution. Experiments have proved that such impregnating material, knife coating material, and back coating material not only have a high recycling rate, but also the synthetic leather made from them has good hydrolysis resistance. Among them, the physical property indexes of the recyclable bio - based polyurethane resin adopted are preferably: solid content is 30%, hundred - percent modulus is 60 - 80, tensile strength is greater than 45 MPa, elongation at break is greater than or equal to 500%, and viscosity range is 180,000 - 250,000.

[0025] 2. In order to make the finally prepared synthetic leather have a high recycling rate as a whole, the base fabric can adopt bio - based fully polyester non - woven fabric, so that the synthetic leather has a high recycling rate as a whole.

[0026] 3. By causing the base fabric after knife coating to form at least three layers of folds in the coagulating liquid, the coagulation effect can be improved, and the holes on the polyurethane surface layer of the synthetic leather can be made uniform and delicate, and the peel strength of the synthetic leather can be increased without affecting other physical properties of the synthetic leather. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0028] Figure 1 It is a flowchart of the preparation method of the synthetic leather based on the recyclable bio-based polyurethane resin in this embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are the preferred embodiments of the present invention and should not be regarded as excluding other embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0030] In the claims, the description and the above-mentioned drawings of the present invention, unless otherwise clearly defined, when using terms such as "first", "second" or "third", etc., are used to distinguish different objects and are not used to describe a specific order.

[0031] In the claims, the description and the above-mentioned drawings of the present invention, unless otherwise clearly defined, for orientation terms, when using terms such as "center", "horizontal", "vertical", "level", "vertical", "top", "bottom", "inner", "outer", "upper", "lower", "front", "rear", "left", "right", "clockwise", "counterclockwise", etc. to indicate the orientation or position relationship, it is based on the orientation and position relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, so it cannot be understood as limiting the specific protection scope of the present invention.

[0032] In the claims, the description and the above-mentioned drawings of the present invention, unless otherwise clearly defined, when using terms such as "fixed connection" or "fixedly connected", should be understood in a broad sense, that is, any connection method without displacement relationship and relative rotation relationship between the two, that is, including non-detachable fixed connection, detachable fixed connection, being integrally connected, and being fixedly connected through other devices or elements.

[0033] In the claims, the description and the above-mentioned drawings of the present invention, when the terms "comprising", "having" and their variants are used, are intended to mean "including but not limited to".

[0034] In the claims, the description and the above-mentioned drawings of the present invention, the term "sugar degree" means the DMF concentration in the DMF aqueous solution.

[0035] This embodiment provides a synthetic leather based on recyclable bio-based polyurethane resin, which is prepared by impregnating a base fabric, pre-solidifying, knife coating, solidifying, first water washing, back coating, second water washing and drying.

[0036] Among them, in parts by mass, the impregnating material used for impregnation is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 540 - 560 parts of dimethylformamide, 14 - 16 parts of tear-resistant resin and 3 - 20 parts of color paste, and then controlling the viscosity to be less than or equal to 30 CPS and the temperature to be normal temperature. The knife coating material used for knife coating is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 35 - 45 parts of dimethylformamide, 0.5 - 1.5 parts of non-ionic surfactant, 0.5 - 1 part of fluorine-free water-resistant additive and 1 - 3 parts of color paste, defoaming, and then controlling the viscosity to be 13000 - 15000 CPS and the temperature to be 32 - 36 °C. The back coating material used for back coating is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 340 - 360 parts of dimethylformamide, 1 - 2 parts of fluorine-free water-resistant additive and 3 - 20 parts of color paste, and then controlling the viscosity to be 100 - 140 CPS and the temperature to be normal temperature.

[0037] In this embodiment, the base fabric is made of bio-based fully polyester non-woven fabric, with a thickness of 0.7 mm and a gram weight of 200 g / m 2 , and the physical property is that the bursting strength is greater than or equal to 18 kgf / cm 2, the tensile load is greater than or equal to 350 N / 3 cm, and the elongation is greater than or equal to 30%-70%. As needed, the physical properties of the synthetic leather obtained can be adjusted by adjusting the physical properties of the base fabric. The physical properties of the recyclable bio-based polyurethane resin used are as follows: the solid content is 30%, the hundred percent modulus is 60-80, the tensile strength is greater than 45 MPa, the elongation at break is greater than or equal to 500%, and the viscosity range is 180,000-250,000. The ratio of the impregnating material used is 100 parts of recyclable bio-based polyurethane resin, 550 parts of dimethylformamide, 15 parts of tear-resistant resin, and 8 parts of color paste. The ratio of the knife coating material used is 100 parts of recyclable bio-based polyurethane resin, 40 parts of dimethylformamide, 1 part of non-ionic surfactant, 1 part of fluorine-free water-resistant aid, and 3 parts of color paste. The ratio of the back coating material used is 100 parts of recyclable bio-based polyurethane resin, 350 parts of dimethylformamide, 2 parts of fluorine-free water-resistant aid, and 12 parts of color paste.

[0038] As Figure 1 shown, the specific process for preparing the synthetic leather based on recyclable bio-based polyurethane resin in this example is as follows:

[0039] S1, impregnation: After the base fabric is unrolled by the uncoiler, it first passes through the fabric storage rack, and the fabric storage rack feeds the base fabric into the impregnating material in the impregnating tank for impregnation, and the impregnation pressure is 5-5.5 kg. The impregnating material used is as described above.

[0040] S2, pre-solidification: The impregnated base fabric is fed into the pre-solidification liquid in the pre-solidification tank for pre-solidification, the pre-solidification pressure is 5-5.5 kg, and the sugar content of the pre-solidification liquid is 28%-32%.

[0041] S3, knife coating: The pre-solidified base fabric is ironed by a six-wheel ironing device, and the ironing temperature is about 50 °C, and then the knife coating material is applied to it by knife coating through the coating table. The knife coating material used for knife coating is as described above. The thickness of the knife coating can be controlled by adjusting the gap of the scraper. In this example, the gap and the coating amount of the knife coating are 205-215 filaments and 1.15-1.25 kg / y respectively.

[0042] S4, solidification: The knife-coated base fabric is fed into the solidification liquid in the main solidification tank for solidification, and the angle between it and the liquid surface of the solidification liquid when it is fed in is 30°, and it forms at least three layers of folds in the solidification liquid. In this example, the knife-coated base fabric forms five layers of folds in the solidification liquid. The sugar content of the solidification liquid is 18-22%, and the temperature is 28-32 °C.

[0043] S5, first water washing: The solidified base fabric is fed into the first water washing tank for the first water washing. The first water washing tank is divided into six groups, and the sugar content of the washing liquid used for the first water washing is 20-22%, and the temperature is normal temperature.

[0044] S6, Back coating: Feed the base fabric after the first water wash into the back coating machine for back coating. The back coating material used for back coating is as described above.

[0045] S7, Second water wash: Feed the base fabric after back coating into the second water wash tank for the second water wash. The second water wash is carried out in two steps. In the first step, six groups of water wash tanks are used, the temperature of the wash liquid is normal temperature, and the sugar content is 0%. In the second step, three groups of water wash tanks are used, the temperature of the wash liquid is 60 - 80°C, and the sugar content is 0%.

[0046] S8, Drying: Pre - iron the base fabric after the second water wash with a smoothing roller, the pre - ironing temperature is 100 - 120°C, then feed it into the oven for drying, and then feed it into the cooling roller for cooling and winding. Thus, the synthetic leather based on recyclable bio - based polyurethane resin in this embodiment can be obtained. Among them, the oven is divided into five groups. The temperature of the first group of ovens is 150°C, the temperature of the second to fourth groups of ovens is 160°C, and the temperature of the fifth group of ovens is 140°C.

[0047] The performance test of the synthetic leather based on recyclable bio - based polyurethane resin in this embodiment is shown in the following table:

[0048]

[0049]

[0050] It can be seen that compared with ordinary synthetic leather, the physical properties of the synthetic leather in this embodiment have no significant difference, and it also has good hydrolysis resistance, while its recyclability is far higher than that of ordinary synthetic leather.

[0051] In this embodiment, the recyclable bio - based polyurethane resin is not directly used as the impregnating material, knife coating material and back coating material. Instead, it is re - processed and mixed with other materials as raw materials to obtain the impregnating material, knife coating material and back coating material used in this technical solution. Experiments have proved that this kind of impregnating material, knife coating material and back coating material not only have a high recycling rate, but also the synthetic leather made from them has good hydrolysis resistance. Among them, the physical property indexes of the recyclable bio - based polyurethane resin used are preferably: the solid content is 30%, the modulus at 100% is 60 - 80, the tensile strength is greater than 45 MPa, the elongation at break is greater than or equal to 500%, and the viscosity range is 180,000 - 250,000.

[0052] In this embodiment, in order to make the finally prepared synthetic leather have a high recycling rate as a whole, the base fabric can be made of bio - based fully polyester non - woven fabric, so that the synthetic leather has a high recycling rate as a whole.

[0053] In this embodiment, by making the base fabric after knife coating form at least three layers of folds in the coagulating liquid, the coagulation effect can be improved, and the pores of the polyurethane surface layer of the synthetic leather can be made uniform and delicate, and the peel strength of the synthetic leather can be improved without affecting other physical properties of the synthetic leather.

[0054] The above description of the specification and embodiments is used to explain the protection scope of the present invention, but does not constitute a limitation on the protection scope of the present invention. Through the inspiration of the present invention or the above embodiments, those of ordinary skill in the art can combine common general knowledge, ordinary technical knowledge in this field, and / or existing technologies, and through logical analysis, reasoning, or limited experiments, modifications, equivalent replacements, or other improvements to the embodiments of the present invention or some of its technical features should be included within the protection scope of the present invention.

Claims

1. A preparation method of synthetic leather based on recyclable bio-based polyurethane resin, characterized in that, S1: Feed the base fabric into the impregnating material for impregnation, and the impregnation pressure is 5 - 5.5 kg; The impregnating material used for impregnation is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 540 - 560 parts of dimethylformamide, 14 - 16 parts of tear-resistant resin, and 3 - 20 parts of color paste by mass. After that, the viscosity is controlled to be less than or equal to 30 CPS, and the temperature is controlled at room temperature. S2: Feed the impregnated base fabric into the pre-curing liquid for pre-curing, and the pre-curing pressure is 5 - 5.5 kg. The sugar content of the pre-curing liquid is 28 - 32%. S3: Iron the pre-cured base fabric flat, and apply the knife coating material on it by knife coating through a coating table; The knife coating material used for knife coating is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 35 - 45 parts of dimethylformamide, 0.5 - 1.5 parts of non-ionic surfactant, 0.5 - 1 part of fluorine-free water-resistant additive, and 1 - 3 parts of color paste by mass. After defoaming by stirring evenly, the viscosity is controlled to be 13000 - 15000 CPS, and the temperature is controlled at 32 - 36 °C. S4: Feed the knife-coated base fabric into the coagulating liquid to form three-layer folded coagulation. The sugar content of the coagulating liquid is 18 - 22%, and the temperature is 28 - 32 °C. S5: Conduct the first water washing on the coagulated base fabric. The sugar content of the washing liquid used for the first water washing is 20 - 22%, and the temperature is room temperature. S6: Feed the base fabric after the first water washing into a back coating machine for back coating. The back coating material used for back coating is prepared by uniformly stirring 100 parts of recyclable bio-based polyurethane resin, 340 - 360 parts of dimethylformamide, 1 - 2 parts of fluorine-free water-resistant additive, and 3 - 20 parts of color paste by mass. After that, the viscosity is controlled to be 100 - 140 CPS, and the temperature is controlled at room temperature. S7: Conduct the second water washing on the back-coated base fabric. The second water washing is carried out in two steps. The temperature of the washing liquid in the first step is room temperature, and the sugar content is 0%; The temperature of the washing liquid in the second step is 60 - 80 °C, and the sugar content is 0%. S8: Iron the base fabric after the second water washing with a pre-ironing roller, and then send it into an oven for drying.

2. The preparation method of synthetic leather based on recyclable bio-based polyurethane resin according to claim 1, characterized in that, The optimal ratio of the impregnating material is 100 parts of recyclable bio-based polyurethane resin, 550 parts of dimethylformamide, 15 parts of tear-resistant resin, and 8 parts of color paste; The optimal ratio of the knife coating material is 100 parts of recyclable bio-based polyurethane resin, 40 parts of dimethylformamide, 1 part of non-ionic surfactant, 1 part of fluorine-free water-resistant additive, and 3 parts of color paste; The optimal ratio of the back coating material is 100 parts of recyclable bio-based polyurethane resin, 350 parts of dimethylformamide, 2 parts of fluorine-free water-resistant additive, and 12 parts of color paste.

3. The preparation method of a synthetic leather based on recyclable bio-based polyurethane resin according to claim 1, characterized in that, The base fabric is bio-based fully polyester non-woven fabric.

4. The preparation method of a synthetic leather based on recyclable bio-based polyurethane resin according to claim 1, characterized in that, The gap and coating amount of the coating obtained by knife coating on the base fabric are 205 - 215 filaments and 1.15 - 1.25 kg / y respectively.

5. The preparation method of a synthetic leather based on recyclable bio-based polyurethane resin according to claim 1, characterized in that, The physical properties of the recyclable bio-based polyurethane resin are as follows: the solid content is 30%, the modulus at 100% is 60 - 80, the tensile strength is greater than 45 MPa, the elongation at break is greater than or equal to 500%, and the viscosity range is 180,000 - 250,000.

6. The preparation method of a synthetic leather based on recyclable bio-based polyurethane resin according to claim 1, characterized in that, The base fabric after knife coating forms five - layer folding in the coagulating liquid.

7. The preparation method of a synthetic leather based on recyclable bio-based polyurethane resin according to claim 1, characterized in that, The oven is divided into five groups. The oven temperature of the first group is 150 °C, the oven temperatures of the second to fourth groups are 160 °C, and the oven temperature of the fifth group is 140 °C.

8. A synthetic leather based on recyclable bio-based polyurethane resin, which is prepared by using the preparation method of a synthetic leather based on recyclable bio-based polyurethane resin according to any one of claims 1 - 7.

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