A waterborne polyurethane dispersion with a high bio-based content for synthetic leather and its preparation method

Abstract

The present invention discloses an aqueous polyurethane dispersion with a high bio-based content for synthetic leather and a preparation method thereof. The aqueous polyurethane dispersion is prepared from the following components in parts by mass: 10.0 - 15.0 parts of bio-based isocyanate, 20.0 - 30.0 parts of bio-based polylactic acid polyol, 1.0 - 2.5 parts of bio-based chain extender, 0.5 - 1.0 part of environmentally friendly catalyst, 0.5 - 1.0 part of bio-based antioxidant, 1.0 - 2.5 parts of neutralizing agent, 0.5 - 3.0 parts of post-chain extender, and 75.0 - 100.0 parts of deionized water. The present invention uses the carboxyl group in the side chain of bio-based polylactic acid polyol as the hydrophilic group and prepares an aqueous polyurethane dispersion with a high bio-based content by the self-emulsification method. The obtained aqueous polyurethane has stable properties. The particle size of the aqueous polyurethane dispersion is less than 100 nm, and it can be stably stored for 6 months at room temperature. The bio-based content of the film formed by drying the aqueous polyurethane dispersion is between 80% and 95%, the tensile strength is greater than 35 MPa, and the elongation at break is greater than 1000%. This aqueous polyurethane dispersion with a high bio-based content is suitable for preparing polyurethane synthetic leather with a high bio-based content.

Description

Technical Field

[0001] The present invention relates to the field of aqueous polyurethanes for synthetic leather, and particularly to an aqueous polyurethane dispersion with a high bio-based content for synthetic leather and a preparation method thereof. Background Art

[0002] In recent years, China's synthetic leather industry has continued to grow steadily. Among them, polyurethane synthetic leather has gradually expanded its market share due to its strong leather-like feel, excellent adhesion performance to substrates, abrasion resistance, and anti-aging properties. Currently, polyurethanes for synthetic leather mainly include three categories: aqueous polyurethanes, solvent-based polyurethanes, and solvent-free polyurethanes. Among them, aqueous polyurethanes use water as the dispersion medium, have a simple preparation process, good storage stability of the dispersion, and the polyurethane film formed by the dispersion has good solvent resistance and anti-aging properties, etc., which conform to the current ecological concept of green development. The proportion of aqueous polyurethanes in polyurethane resins for synthetic leather has been increasing year by year.

[0003] To reduce dependence on petroleum resources and lower carbon emissions, the preparation of aqueous polyurethanes from bio-based raw materials has become a development trend. Chinese Patent Application CN112724347A discloses a bio-based aqueous polyurethane resin and its preparation method and application, and Chinese Patent CN114085356A discloses a surface layer polyurethane resin for synthetic leather with chemical resistance and biodegradability and its preparation method. However, the existing bio-based polyurethanes for synthetic leather have a low bio-based content and use toxic tin-based catalysts, and the performance of the bio-based polyurethane dispersion and film is unstable. The present invention uses a variety of bio-based raw materials to significantly increase the bio-based content in bio-based aqueous polyurethanes, replaces toxic tin-based catalysts with environmentally friendly catalysts, and at the same time ensures the stable performance of the high bio-based content aqueous polyurethanes for synthetic leather, the aqueous polyurethane dispersion has good storage stability, and the aqueous polyurethane film has good mechanical properties. Summary of the Invention

[0004] The purpose of the present invention is to provide an aqueous polyurethane dispersion with a high bio-based content for synthetic leather and a preparation method thereof.

[0005] The present invention prepares aqueous polyurethanes through a variety of bio-based raw materials, achieving a bio-based content greater than 80%, and replacing toxic tin-based catalysts with environmentally friendly catalysts. The polylactic acid polyol obtained by copolymerizing L-lysine with a carboxyl side chain and bio-based trimethylene carbonate is selected as the soft segment, and the carboxyl group in the side chain of the polylactic acid polyol is used as the hydrophilic group. Moreover, through the combined action of the carbonate bond and ester bond in the polylactic acid polyol, the aqueous polyurethane dispersion with a high bio-based content for synthetic leather is given high stability, and the film formed by the dispersion has outstanding mechanical properties.

[0006] To achieve the above and other related objectives, the present invention provides an aqueous polyurethane dispersion with a high bio-based content for synthetic leather, which is prepared from the following components:

[0007]

[0008] In some embodiments of the invention, the bio-based isocyanate is one or a combination of L-lysine diisocyanate, 1,5-pentane diisocyanate, or dimer acid diisocyanate.

[0009] In some embodiments of the invention, the structural formula of the bio-based polylactic acid polyol is

[0010]

[0011] Wherein, the sum of m, n, x, and y is selected from integers between 16 and 36.

[0012] In some embodiments of the invention, the bio-based polylactic acid polyol is prepared by ring-opening copolymerization of L-lactide and bio-based trimethylene carbonate with a bio-based small molecule L-lysine containing a carboxyl side chain in the structure as an initiator under the action of an organic catalyst 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0013] In some embodiments of the invention, the bio-based chain extender is one or a combination of bio-based ethylene glycol, bio-based 1,4-butanediol, bio-based 2,3-butanediol, bio-based 1,5-pentanediol, or bio-based isosorbide.

[0014] In some embodiments of the invention, the environmental protection catalyst is one or a combination of zinc isooctanoate, bismuth neodecanoate, or bismuth isooctanoate.

[0015] In some embodiments of the invention, the bio-based antioxidant is one or a combination of bio-based glycyrrhizin or bio-based 3,4,5,7-tetrahydroxyflavone.

[0016] In some embodiments of the invention, the neutralizing agent is one or a combination of triethylamine, sodium bicarbonate, sodium acetate, sodium pyrophosphate, or sodium carbonate.

[0017] In some embodiments of the invention, the post-chain extender is one or a combination of ethylenediamine, triethylenediamine, or isophorone diamine.

[0018] The present invention also provides a method for preparing the above-mentioned aqueous polyurethane dispersion with a high bio-based content for synthetic leather, comprising the following steps:

[0019] Add 20.0 - 30.0 parts by mass of bio - based poly(lactic acid) polyol, 10.0 - 15.0 parts by mass of bio - based isocyanate, 1.0 - 2.5 parts by mass of bio - based chain extender, 0.5 - 1.0 parts by mass of bio - based antioxidant and 0.5 - 1.0 parts by mass of environmentally friendly catalyst into the reactor, react at 60°C - 90°C for 6h - 9h, and add acetone during the reaction process to adjust the viscosity of the reaction system;

[0020] After cooling the reaction system, add 1.0 - 2.5 parts by mass of neutralizer to neutralize the reaction system, add 0.5 - 3.0 parts by mass of post - chain extender and 75.0 - 100.0 parts by mass of deionized water, stir at high speed for 30min - 40min, and then remove acetone to obtain an aqueous polyurethane dispersion with a high bio - based content for synthetic leather.

[0021] In summary, the present invention provides an aqueous polyurethane dispersion with a high bio - based content for synthetic leather and its preparation method. Through molecular design and formulation optimization, while greatly increasing the bio - based component content of the aqueous polyurethane dispersion, the stability of the performance of the aqueous polyurethane dispersion with a high bio - based content is ensured, so that the aqueous polyurethane dispersion has good storage stability at room temperature. At the same time, the mechanical properties of the film formed by the aqueous polyurethane dispersion are good, which is suitable for the production of high - performance polyurethane synthetic leather with a high bio - based content. Brief Description of the Drawings

[0022] Figure 1 It is a schematic flow chart of the preparation method of the aqueous polyurethane dispersion with a high bio - based content for synthetic leather in the embodiment.

[0023] Figure 2 It is a schematic flow chart of preparing a polyurethane synthetic leather with a high bio - based content from the aqueous polyurethane dispersion with a high bio - based content in the embodiment. Detailed Embodiments

[0024] The following specific examples illustrate the embodiments of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0025] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented here. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Unless otherwise specified, "%" and "parts" shown in the following examples respectively refer to "mass %" and "parts by mass".

[0026] The present invention provides an aqueous polyurethane dispersion with a high bio-based content for synthetic leather, and the bio-based content is between 80% and 95%. The synthetic leather prepared from the aqueous polyurethane dispersion with a high bio-based content obtained by the present invention meets the performance requirements of synthetic leather for furniture aqueous polyurethane synthetic leather, clothing polyurethane synthetic leather, automotive decorative leather and other fields, and can be widely used in furniture, clothing, automotive decoration and other fields.

[0027] In the embodiments of the present invention, the aqueous polyurethane dispersion with a high bio-based content for synthetic leather includes raw materials such as bio-based isocyanate and bio-based polylactic acid polyol. Among them, the content of bio-based isocyanate is, for example, 10.0 to 15.0 parts by mass, and the bio-based isocyanate is, for example, one or a mixture of several of L-lysine diisocyanate, 1,5-pentane diisocyanate or dimer acid diisocyanate. The content of bio-based polylactic acid polyol is, for example, 20.0 to 30.0 parts by mass, and the bio-based polylactic acid polyol is, for example, obtained by ring-opening copolymerization of an initiator with L-lactide and bio-based trimethylene carbonate under the action of an organic catalyst. Among them, the initiator is, for example, a bio-based small molecule with a carboxyl side chain in the structure, and for another example, L-lysine, and the organic catalyst is, for example, 1,8-diazabicycloundec-7-ene. In the embodiments of the present invention, the bio-based polylactic acid polyol has, for example, the following structural formula,

[0028]

[0029] Among them, the sum of m, n, x, and y in the structural formula is, for example, an integer selected from 16 to 36. L-lysine introduces a carboxyl group into the polyurethane molecular chain, and the carboxyl group serves as an anionic hydrophilic group. After neutralization, it provides a protonated hydrophilic unit for the polyurethane chain, realizing the self-emulsification of polyurethane in water without adding a hydrophilic chain extender to achieve the hydrophilicity of polyurethane. The prepared aqueous polyurethane dispersion has a particle size lower than 100 nm and can be stably stored at room temperature for 6 months.

[0030] In the embodiments of the present invention, in the aqueous polyurethane dispersion, the aqueous polyurethane dispersion with a high bio-based content for synthetic leather further includes raw materials such as a bio-based chain extender, an environmental protection catalyst, a bio-based antioxidant, a neutralizing agent, a post-chain extender and deionized water. Among them, the content of the bio-based chain extender is, for example, 1.0 to 2.5 parts by mass, and for another example, 1.0, 2.0 or 2.5 parts by mass. The bio-based chain extender is, for example, one or more of bio-based ethylene glycol, bio-based 1,4-butanediol, bio-based 2,3-butanediol, bio-based 1,5-pentanediol or bio-based isosorbide. For another example, it is bio-based ethylene glycol, bio-based 2,3-butanediol or bio-based 1,4-butanediol.

[0031] In the embodiments of the present invention, in the aqueous polyurethane dispersion, the content of the environmentally friendly catalyst is, for example, 0.5 to 1.0 parts by mass, and for example, 0.5, 0.6 or 1.0 parts by mass. The environmentally friendly catalyst is, for example, one of zinc isooctanoate, bismuth neodecanoate or bismuth isooctanoate, and for example, bismuth neodecanoate or zinc isooctanoate. The content of the bio-based antioxidant is, for example, 0.5 to 1.0 parts by mass, and for example, 0.5, 0.7 or 1.0 parts by mass. The bio-based antioxidant is, for example, one of bio-based glycyrrhizin or bio-based 3,4,5,7-tetrahydroxyflavone. In this embodiment, the bio-based antioxidant is, for example, bio-based glycyrrhizin or bio-based 3,4,5,7-tetrahydroxyflavone.

[0032] In the embodiments of the present invention, in the aqueous polyurethane dispersion, the content of the neutralizing agent is, for example, 1.0 to 2.5 parts by mass, and for example, 1.0, 1.3 or 2.5 parts by mass. The neutralizing agent is, for example, one or more of triethylamine, sodium bicarbonate, sodium acetate, sodium pyrophosphate or sodium carbonate, and for example, triethylamine, sodium carbonate or sodium pyrophosphate. The content of the post-chain extender is, for example, 0.5 to 3.0 parts by mass, and for example, 0.5, 1.5 or 3.0 parts by mass. The post-chain extender is one or more of ethylenediamine, triethylenediamine or isophorone diamine, and for example, ethylenediamine, triethylenediamine or isophorone diamine. In the aqueous polyurethane dispersion, the content of deionized water is, for example, 75.0 to 100.0 parts by mass, and for example, 75.0, 90.0 or 100.0 parts by mass.

[0033] As Figure 1 shown, the present invention provides a method for preparing an aqueous polyurethane dispersion with a high bio-based content for synthetic leather, and the preparation method includes steps S10 to S20.

[0034] Step S10: Add, for example, 20.0 to 30.0 parts by mass of bio-based polylactic acid polyol, 10.0 to 15.0 parts by mass of bio-based isocyanate, 1.0 to 2.5 parts by mass of bio-based chain extender, 0.5 to 1.0 parts by mass of bio-based antioxidant and 0.5 to 1.0 parts by mass of environmentally friendly catalyst into a reactor, react at, for example, 60°C to 90°C, the reaction time is, for example, 6 h to 9 h, and acetone is added during the reaction to adjust the viscosity of the reaction system;

[0035] Step S20: Cool down the reaction system in step S10. After cooling, neutralize the reaction system with, for example, 1.0 to 2.5 parts by mass of a neutralizing agent, then add, for example, 0.5 to 3.0 parts by mass of a post-chain extender and 75.0 to 100.0 parts by mass of deionized water, stir at high speed, the stirring time is, for example, 30 min to 40 min, and remove acetone to obtain an aqueous polyurethane dispersion with a high bio-based content for synthetic leather.

[0036] As Figure 1As shown, in the embodiment of the present invention, in step S10, the number-average molecular weight of the bio-based polylactic acid polyol is, for example, 2000 g / mol. Before the bio-based polylactic acid polyol reacts with the bio-based isocyanate, a vacuum dehydration reaction is carried out under preset temperature and vacuum conditions. The preset temperature is, for example, 105°C, the vacuum is, for example, greater than 0.085 MPa, and the time for the vacuum dehydration reaction is, for example, 1 h.

[0037] As Figure 1 shown, in the embodiment of the present invention, in step S10, in the reaction vessel, the bio-based polylactic acid polyol after the vacuum dehydration reaction, for example, 20.0 - 30.0 parts by mass, is cooled to, for example, 90°C, and then 10.0 - 15.0 parts by mass of the bio-based isocyanate is added for reaction. The reaction time is, for example, 2 h - 3 h, and it is cooled to, for example, 60°C. Then, 1.0 - 2.5 parts by mass of the bio-based chain extender, 0.5 - 1.0 part by mass of the bio-based antioxidant, and 0.5 - 1.0 part by mass of the environmentally friendly catalyst are added. Then, it is heated to, for example, 80°C for constant-temperature reaction. The reaction time is, for example, 4 h - 6 h, and acetone is added during the reaction process to adjust the viscosity of the reaction system.

[0038] As Figure 1 shown, in the embodiment of the present invention, in step S20, the reaction system in step S10 is cooled to, for example, 40°C, 1.0 - 2.5 parts by mass of the neutralizing agent is added to the reaction system. After the neutralization reaction for, for example, 10 min - 20 min, 0.5 - 3.0 parts by mass of the post-chain extender and 75.0 - 100.0 parts by mass of deionized water are added, and high-speed stirring is carried out. The stirring time is, for example, 30 min - 40 min to complete emulsification. After the reaction ends, it is left standing and acetone is removed. For example, the vacuum distillation method is used to remove acetone to obtain the waterborne polyurethane dispersion with a high bio-based content.

[0039] In the embodiment of the present invention, a preparation method of a waterborne polyurethane synthetic leather with a high bio-based content is also provided. The preparation method includes steps S11 - S12.

[0040] Step S11: Coating the waterborne polyurethane dispersion with a high bio-based content on the release paper, and the coating amount is, for example, 500 g / m 2 , and drying it in an oven at 120°C to form a continuous and uniform polyurethane film.

[0041] Step S12: Scraping and coating an amino resin binder on the obtained polyurethane film, laminating it with a non-woven fabric, and using a peeling device to peel off the release paper to obtain the waterborne polyurethane synthetic leather with a high bio-based content.

[0042] In the embodiments of the present invention, the particle size and centrifugal acceleration sedimentation of the aqueous polyurethane dispersion with a high bio-based content in Test Examples 1 to 3 were tested. The centrifugal speed was, for example, 3000 r / min, and the centrifugal time was, for example, 15 min. The tensile strength and elongation at break of the film formed by the aqueous polyurethane dispersion with a high bio-based content in Test Examples 1 to 3 were tested. At the same time, the physical properties such as the thickness, apparent density, rubbing color fastness, abrasion resistance, and folding endurance of the aqueous polyurethane synthetic leather with a high bio-based content in Test Examples 1 to 3 were tested.

[0043] Specific embodiments will be introduced below to elaborate on the present invention in more detail.

[0044] Example 1

[0045] Prepare an aqueous polyurethane dispersion with a high bio-based content for synthetic leather.

[0046] Step S10: Add 20.0 parts by mass of polylactic acid diol with a number average molecular weight of 2000 g / mol to the reactor. Under the conditions of a temperature of 105°C and a vacuum degree greater than 0.085 MPa, carry out a dehydration reaction under reduced pressure for 1 h. Cool down to 90°C, add 10.0 parts of 1,5-pentane diisocyanate to the reactor, and keep the temperature constant for 2 h. Then cool down to 60°C, add 1.0 part of bio-based ethylene glycol, 0.5 part of bio-based glycyrrhizin, and 0.5 part of the environmental protection catalyst bismuth neodecanoate to the reactor, and then heat up to 80°C and keep the temperature constant for 4 h. During the reaction process, acetone was added to adjust the viscosity of the system.

[0047] Step S20: Cool down the reaction system in Step S10 to 40°C, add 1.0 part of the neutralizing agent triethylamine to the reactor, react for 10 min, then add 0.5 part of the post-chain extender ethylenediamine and 75.0 parts of deionized water, and stir at high speed for 30 min to complete the emulsification reaction. After completion, let it stand and then remove acetone to obtain an aqueous polyurethane dispersion with a high bio-based content.

[0048] Prepare an aqueous polyurethane synthetic leather with a high bio-based content.

[0049] Step S11: Coat the aqueous polyurethane dispersion with a high bio-based content prepared in Step S20 on the release paper, and the coating amount is 500 g / m 2 , and dry it in an oven at 120°C to form a continuous and uniform polyurethane film.

[0050] Step S12: Knife-coat an amino resin binder on the polyurethane film prepared in Step S12, laminate it with the non-woven fabric, and use a peeling device to peel off the release paper to obtain an aqueous polyurethane synthetic leather with a high bio-based content.

[0051] Example 2

[0052] Prepare an aqueous polyurethane dispersion with a high bio-based content for synthetic leather.

[0053] Step S10: Add 25.0 parts by mass of polylactic acid diol with a number average molecular weight of 2000 g / mol to the reactor. Under the conditions of a temperature of 105°C and a vacuum degree greater than 0.085 MPa, carry out a reduced-pressure dehydration reaction for 1 h. Cool down to 90°C, add 12.0 parts of L-lysine diisocyanate to the reactor, and after reacting at a constant temperature for 3 h. Cool down to 60°C, add 2.0 parts of bio-based 2,3-butanediol, 0.7 part of bio-based 3,4,5,7-tetrahydroxyflavone, and 0.6 part of the environmentally friendly catalyst zinc isooctanoate to the reactor, and then raise the temperature to 80°C and react at a constant temperature for 5 h. During the reaction process, add acetone to adjust the viscosity of the system.

[0054] Step S20: Cool down the reaction system in Step S10 to 40°C, add 1.3 parts of the neutralizing agent sodium carbonate to the reactor, react for 15 min, then add 1.5 parts of the post-chain extender triethylenediamine and 90.0 parts of deionized water, and stir at high speed for 35 min to complete the emulsification reaction. After completion, let it stand and then remove acetone to obtain an aqueous polyurethane dispersion with a high bio-based content.

[0055] Prepare a synthetic leather made of aqueous polyurethane with a high bio-based content.

[0056] Step S11: Coat the aqueous polyurethane dispersion with a high bio-based content prepared in Step S20 on the release paper, and the coating amount is 500 g / m 2 , and dry it in an oven at 120°C to form a continuous and uniform polyurethane film.

[0057] Step S12: Knife-coat an amino resin binder on the polyurethane film prepared in Step S12, laminate it with a non-woven fabric, and use a peeling device to peel off the release paper to obtain a synthetic leather made of aqueous polyurethane with a high bio-based content.

[0058] Example 3

[0059] Prepare an aqueous polyurethane dispersion with a high bio-based content for synthetic leather.

[0060] Step S10: Add 30.0 parts by mass of polylactic acid diol with a number average molecular weight of 2000 g / mol to the reactor. Under the conditions of a temperature of 105°C and a vacuum degree greater than 0.085 MPa, carry out a reduced-pressure dehydration reaction for 1 h. Cool down to 90°C, add 15.0 parts of dimer acid diisocyanate to the reactor, and after reacting at a constant temperature for 3 h. Cool down to 60°C, add 2.5 parts of bio-based 1,4-butanediol, 1.0 part of bio-based 3,4,5,7-tetrahydroxyflavone, and 1.0 part of the environmentally friendly catalyst zinc isooctanoate to the reactor, and then raise the temperature to 80°C and react at a constant temperature for 6 h. During the reaction process, add acetone to adjust the viscosity of the system.

[0061] Step S20: Cool down the reaction system in Step S10 to 40°C, add 2.5 parts of neutralizing agent sodium pyrophosphate to the reactor, react for 20 min, then add 3.0 parts of chain extender isophorone diamine and 100.0 parts of deionized water, stir at high speed for 40 min to complete the emulsification reaction. After completion, let it stand and then remove acetone to obtain a waterborne polyurethane dispersion with a high bio-based content.

[0062] Prepare a waterborne polyurethane synthetic leather with a high bio-based content.

[0063] Step S11: Coat the waterborne polyurethane dispersion with a high bio-based content prepared in Step S20 on the release paper, with a coating amount of 500 g / m 2 , dry it in an oven at 120°C to form a continuous and uniform polyurethane film.

[0064] Step S12: Knife-coat an amino resin binder on the polyurethane film prepared in Step S12, laminate it with a non-woven fabric, and use a peeling device to peel off the release paper to obtain a waterborne polyurethane synthetic leather with a high bio-based content.

[0065] The performance data of the waterborne polyurethane dispersions with a high bio-based content and the waterborne polyurethane film adhesives with a high bio-based content prepared in Examples 1 to 3 are shown in Table 1.

[0066] Table 1 Performance data of the waterborne polyurethane dispersions with a high bio-based content and the waterborne polyurethane film adhesives with a high bio-based content prepared in Examples 1 to 3

[0067]

[0068] The performance data of the waterborne polyurethane synthetic leathers with a high bio-based content prepared in Examples 1 to 3 are shown in Table 2.

[0069] Table 2 Performance of the waterborne polyurethane synthetic leathers with a high bio-based content prepared in Examples 1 to 3

[0070]

[0071] As can be seen from Table 1, the waterborne polyurethanes with a high bio-based content for synthetic leathers prepared in Examples 1 to 3 have stable performance. The particle size of the waterborne polyurethane dispersion is less than 100 nm and can be stably stored for 6 months at room temperature. Moreover, the bio-based component content in the waterborne polyurethane film adhesives with a high bio-based content prepared in Examples 1 to 3 is greater than 80%, and the mechanical properties such as tensile strength and elongation at break are excellent.

[0072] As can be seen from Table 2, the waterborne polyurethanes with high bio-based content prepared in Examples 1 to 3 were made into synthetic leather, and the properties of the synthetic leather such as thickness, apparent density, rubbing fastness, abrasion resistance and flexing fastness were tested. The prepared synthetic leather meets the performance requirements of synthetic leather for different fields. The synthetic leather prepared with the waterborne polyurethane obtained in Example 1 meets the performance requirements of waterborne polyurethane synthetic leather for furniture. The synthetic leather prepared with the waterborne polyurethane obtained in Example 2 meets the performance requirements of waterborne polyurethane synthetic leather for clothing. The synthetic leather prepared with the waterborne polyurethane obtained in Example 3 meets the performance requirements of waterborne polyurethane synthetic leather for automotive decoration, making up for the deficiencies in the application of materials with high bio-based content in the direction of synthetic leather in the market.

[0073] In summary, the present invention provides a waterborne polyurethane dispersion with high bio-based content for synthetic leather and its preparation method. Through molecular design and formulation optimization, a waterborne polyurethane dispersion with high bio-based content for synthetic leather is obtained. Waterborne polyurethane is prepared from a variety of bio-based raw materials, achieving a bio-based content greater than 80%, and replacing toxic tin-based catalysts with environmentally friendly catalysts. The poly(lactic acid) polyol obtained by copolymerizing L-lysine with carboxyl side chains and bio-based trimethylene carbonate is selected as the soft segment, and the carboxyl group in the side chain of the poly(lactic acid) polyol is used as the hydrophilic group. Moreover, through the combined action of the carbonate bond and ester bond in the poly(lactic acid) polyol, the waterborne polyurethane dispersion with high bio-based content for synthetic leather is given high stability, and the film formed by the dispersion has outstanding mechanical properties.

[0074] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principle and practical application of the present invention, so that those skilled in the art in the relevant technical field can understand and utilize the present invention well. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A waterborne polyurethane dispersion with a high bio - based content for synthetic leather, characterized in that, it is prepared from the following components: Among them, the structural formula of the bio - based polylactic acid polyol is The sum of m, n, x, and y is selected from integers between 16 and 36; The bio - based polylactic acid polyol is prepared by ring - opening copolymerization of L - lactide and bio - based trimethylene carbonate with a bio - based small molecule L - lysine containing a carboxyl - side chain as an initiator under the action of an organic catalyst 1,8 - diazabicyclo[5.4.0]undec - 7 - ene.

2. The waterborne polyurethane dispersion with a high bio - based content for synthetic leather according to claim 1, characterized in that, The bio - based isocyanate is one or a combination of several of L - lysine diisocyanate, 1,5 - pentane diisocyanate, or dimer acid diisocyanate.

3. The waterborne polyurethane dispersion with a high bio - based content for synthetic leather according to claim 1, characterized in that, The bio - based chain extender is one or a combination of several of bio - based ethylene glycol, bio - based 1,4 - butanediol, bio - based 2,3 - butanediol, bio - based 1,5 - pentanediol, or bio - based isosorbide.

4. The waterborne polyurethane dispersion with a high bio - based content for synthetic leather according to claim 1, characterized in that, The environmental - friendly catalyst is one or a combination of several of zinc isooctanoate, bismuth neodecanoate, or bismuth isooctanoate.

5. The waterborne polyurethane dispersion with a high bio - based content for synthetic leather according to claim 1, characterized in that, The bio - based antioxidant is one or a combination of two of bio - based glycyrrhizin or bio - based 3,4,5,7 - tetrahydroxyflavone.

6. The waterborne polyurethane dispersion with a high bio - based content for synthetic leather according to claim 1, characterized in that, The neutralizer is one or a combination of several of triethylamine, sodium bicarbonate, sodium acetate, sodium pyrophosphate, or sodium carbonate.

7. The waterborne polyurethane dispersion with a high bio - based content for synthetic leather according to claim 1, characterized in that, The post - chain extender is one or a combination of several of ethylenediamine, triethylenediamine, or isophorone diamine.

8. A method for preparing the waterborne polyurethane dispersion with a high bio - based content for synthetic leather according to any one of claims 1 - 7, characterized in that, it includes the following steps: Add 20.0 - 30.0 parts by mass of bio - based polylactic acid polyol, 10.0 - 15.0 parts by mass of bio - based isocyanate, 1.0 - 2.5 parts by mass of bio - based chain extender, 0.5 - 1.0 parts by mass of bio - based antioxidant, and 0.5 - 1.0 parts by mass of environmental - friendly catalyst into a reactor, react at 60°C - 90°C for 6h - 9h, and add acetone during the reaction to adjust the viscosity of the reaction system; After cooling the reaction system, add 1.0 - 2.5 parts by mass of neutralizer to neutralize the reaction system, add 0.5 - 3.0 parts by mass of post - chain extender and 75.0 - 100.0 parts by mass of deionized water, stir at high speed for 30min - 40min, and then remove acetone to obtain the waterborne polyurethane dispersion with a high bio - based content for synthetic leather.

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