Waterborne polyurethane slurry, coated fabric and preparation method and application thereof
By adding bacterial cellulose hydrogel to waterborne polyurethane slurry, film-forming properties and leveling properties are enhanced, the problem of pinholes during printing is solved, and the uniformity of printing and cross-linking of the foam structure are achieved.
Patent Information
- Application Number
- CN202510929480.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-07
- Publication Date
- 2025-11-25
AI Technical Summary
During the screen printing process, the ink paste is prone to pinholes, which can damage the integrity of the printed coating and prevent it from being evenly covered on the substrate surface.
By adding bacterial cellulose hydrogel to waterborne polyurethane slurry, the film-forming properties, leveling and self-healing ability of the slurry are enhanced, and the formation of pores is avoided by utilizing the interaction of hydrogen bonds and dynamic covalent bonds.
It achieves smooth and uniform printing, avoids the formation of pinholes, enhances the cross-linking of the foam structure, and saves costs.
Abstract
Description
Technical Field
[0001] This invention relates to the field of footwear manufacturing, and in particular to a water-based polyurethane slurry, a coated fabric, its preparation method, and its application. Background Technology
[0002] Under screen printing conditions, air bubbles or impurities in the ink paste, excessively high viscosity, excessively fast printing speed, poor printing environment, unclean substrate surface, and ink paste that is too thin can all cause pinhole problems during the printing process. In fact, the integrity of the printed coating is damaged. These problems will cause the ink paste to fail to cover the substrate surface evenly during the printing process, forming pinholes (i.e., local ink shortages and holes). In fact, it is the poor overall leveling effect of the ink paste that creates gaps. Summary of the Invention
[0003] In view of the above problems, this application provides an aqueous polyurethane slurry, a coated fabric, a preparation method thereof, and its application. By adding bacterial cellulose hydrogel to this aqueous polyurethane slurry, the film-forming properties, leveling, and self-healing ability of the slurry are enhanced, resulting in smooth and uniform printing, avoiding pinholes, and improving the cross-linking of the foam structure.
[0004] The first aspect of this application provides an aqueous polyurethane slurry for improving trachoma, the aqueous polyurethane slurry comprising 0.4-1 wt% bacterial cellulose hydrogel and 80-90 wt% aqueous polyurethane.
[0005] Unlike existing technologies, by adding bacterial cellulose hydrogel with high water content, the waterborne polyurethane slurry has stronger film-forming properties, better leveling and self-healing ability. Through the interaction of hydrogen bonds and dynamic covalent bonds, the slurry will not have pores, i.e. pinhole areas, on the surface during the film formation process.
[0006] The fibrous network structure within bacterial cellulose hydrogels exhibits excellent water retention, with a maximum water holding capacity exceeding 600 times its dry weight. When a slurry coating is infused with bacterial cellulose hydrogels with high water content, localized fractures occur in the hydrogel, disrupting the gel network and exposing numerous hydroxyl groups on the surface of the bacterial cellulose nanofibers, which then rapidly re-bond. The waterborne polyurethane polymer chains are also affected, exhibiting fractures and slippage. During this process, the exposed hydroxyl groups participate in the reassembly of the gel fracture surfaces, forming hydrogen bonds and establishing a new film-forming state.
[0007] Furthermore, the bacterial cellulose hydrogel is an Acetobacter xylinum cellulose hydrogel.
[0008] Furthermore, the waterborne polyurethane slurry also contains a foaming agent and / or expanded microspheres.
[0009] Furthermore, the viscosity of the waterborne polyurethane slurry is 11,000-15,000 cps.
[0010] The second aspect of this application provides a method for preparing a polyurethane foam coated fabric, comprising the following steps: S1: mixing waterborne polyurethane, pH adjuster, ethylene glycol, defoamer, wetting and dispersing agent, thickener, water and expanding microspheres to obtain a waterborne polyurethane base material;
[0011] S2: Add bacterial cellulose hydrogel to waterborne polyurethane base material, stir at 800-1000 rad / min for 10 min, and then seal and let stand at room temperature for 24-30 h to obtain waterborne polyurethane foam slurry.
[0012] S3: The polyurethane foam slurry is printed onto the surface of the base fabric by screen printing, and after drying, a fabric with a foam coating is obtained.
[0013] S4: Foam the foam coating to obtain the polyurethane foam coated fabric.
[0014] Unlike existing technologies, by adding high-water-content bacterial cellulose hydrogel, the waterborne polyurethane slurry exhibits stronger film-forming properties, superior leveling, and self-healing capabilities. Through the interaction of hydrogen bonds and dynamic covalent bonds, the slurry prevents the formation of pores (pinhole areas) on the surface during the printing process, eliminating the need for pinhole re-inspection and saving costs. In the subsequent thermal foaming process, foaming is also more uniform and complete. Furthermore, the abundant -OH structures and nanofiber network inherent in the bacterial cellulose hydrogel enhance the cross-linking of the foaming structure in the later stages.
[0015] Furthermore, in step S2, the aqueous polyurethane slurry comprises 0.4-1 wt% bacterial cellulose hydrogel and 80-90 wt% aqueous polyurethane.
[0016] Furthermore, in step S2, the bacterial cellulose hydrogel is converted into an Acetobacter xylinum cellulose hydrogel.
[0017] Furthermore, in step S4, the foaming temperature is 120-150℃ and the time is 35-75s.
[0018] Excessive foaming temperature can damage or deactivate the physical structure of bacterial cellulose, potentially causing the nanofiber network to loosen or break, thus reducing its original porosity, water retention, and mechanical strength (such as tensile strength and elastic modulus). Furthermore, it reduces chemical activity: active groups such as hydroxyl groups (-OH) on the cellulose molecular chain may be destroyed or chemically modified, affecting the bonding ability of the foamed structure.
[0019] The third aspect of this application provides a polyurethane foam coated fabric, which is prepared using the preparation method described in the second aspect of this application.
[0020] The fourth aspect of this application provides a sports shoe, wherein the upper of the sports shoe is made of the polyurethane foam coated fabric described in the third aspect of this application.
[0021] The above description of the invention is merely an overview of the technical solution of this application. In order to enable those skilled in the art to better understand the technical solution of this application and to implement it based on the textual description, and to make the above-mentioned objectives and other objectives, features and advantages of this application easier to understand, the following description is based on the specific embodiments of this application. Detailed Implementation
[0022] To explain in detail the technical content, structural features, objectives, and effects of the technical solution, the following detailed description is provided in conjunction with specific embodiments.
[0023] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description is provided in conjunction with the specific embodiments listed. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended only as examples, not as limiting the scope of protection of this application.
[0024] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.
[0025] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.
[0026] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.
[0027] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.
[0028] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.
[0029] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.
[0030] The *Acetobacter xylinum* described in this embodiment is Gram-negative (a few may be variable), strictly aerobic, and its respiratory metabolism never involves fermentation. It is catalase-positive and oxidase-negative. It does not liquefy gelatin, producing indole and H₂S. It oxidizes ethanol to acetic acid. Acetic acid and lactic acid are oxidized to CO₂ and H₂O. Ethanol, glycerol, and lactic acid are the best carbon sources. It can produce acids from n-propanol, n-butanol, and D-glucose. It does not hydrolyze lactose and starch. It is chemoheterotrophic.
[0031] The bacterial cellulose hydrogel described in this embodiment, also known as a gel-like BC membrane, is a thin film material with a gel state obtained by liquid fermentation of microorganisms such as Acetobacter xylinum. It has a nanoscale fiber network structure, in which the fibers interweave to form a porous three-dimensional network structure.
[0032] The first aspect of this application provides an aqueous polyurethane slurry for improving trachoma, the aqueous polyurethane slurry comprising 0.4-1 wt% bacterial cellulose hydrogel and 80-90 wt% aqueous polyurethane.
[0033] Researchers have found that when the viscosity of the polyurethane paste is too low and its fluidity is too high, it easily flows quickly through the mesh during screen printing, even penetrating the substrate before the squeegee has completely covered the screen. This results in uneven ink distribution, and after drying, small holes may appear due to shrinkage or uneven accumulation. Conversely, when the viscosity is too high, the ink's fluidity decreases, making it difficult for the ink to pass smoothly through the mesh during screen printing. When the squeegee passes over the screen, the high-viscosity ink may not be able to fill the mesh evenly due to excessive cohesion, leading to insufficient ink deposition in some areas and resulting in "pinholes" (i.e., localized ink gaps or holes) after printing.
[0034] The fibrous network structure within bacterial cellulose hydrogels exhibits excellent water retention, reaching up to 600 times its dry weight. When high-water-content bacterial cellulose hydrogels are incorporated into the slurry coating, localized fractures occur, disrupting the gel network and exposing numerous hydroxyl groups on the surface of the bacterial cellulose nanofibers, which then rapidly re-bond. The waterborne polyurethane polymer chains are also affected, exhibiting fractures and slippage. During this process, the exposed hydroxyl groups participate in the re-joining of the gel fracture surfaces, forming hydrogen bonds and establishing a new equilibrium. The bacterial cellulose hydrogel effectively regulates the slurry viscosity, avoiding the pinhole printing problems caused by inconsistent ink viscosity.
[0035] Unlike existing technologies, by adding bacterial cellulose hydrogel with high water content, the waterborne polyurethane slurry has stronger film-forming properties, better leveling and self-healing ability. Through the interaction of hydrogen bonds and dynamic covalent bonds, the slurry will not have pores, i.e. pinhole areas, on the surface during the film formation process.
[0036] Furthermore, the bacterial cellulose hydrogel is an Acetobacter xylinum cellulose hydrogel.
[0037] Furthermore, the waterborne polyurethane slurry also contains a foaming agent and / or expanded microspheres.
[0038] Furthermore, the viscosity of the waterborne polyurethane slurry is 11,000-15,000 cps.
[0039] The second aspect of this application provides a method for preparing a polyurethane foam coated fabric, comprising the following steps: S1: mixing waterborne polyurethane, pH adjuster, ethylene glycol, defoamer, wetting and dispersing agent, thickener, water and expanding microspheres to obtain a waterborne polyurethane base material;
[0040] S2: Add bacterial cellulose hydrogel to waterborne polyurethane base material, stir at 800-1000 rad / min for 10 min, and then seal and let stand at room temperature for 24-30 h to obtain waterborne polyurethane foam slurry.
[0041] S3: The polyurethane foam slurry is printed onto the surface of the base fabric by screen printing, and after drying, a fabric with a foam coating is obtained.
[0042] S4: The foam coating is subjected to molding and thermal foaming to obtain the polyurethane foam coated fabric.
[0043] Unlike existing technologies, by adding bacterial cellulose hydrogel with high water content, the waterborne polyurethane slurry has stronger film-forming properties, better leveling and self-healing ability. Through the interaction of hydrogen bonds and dynamic covalent bonds, the slurry will not have pores, i.e. pinhole areas, on the surface during the film formation process, eliminating the need for pinhole re-inspection of the product and saving costs.
[0044] Furthermore, in step S2, the aqueous polyurethane slurry comprises 0.4-1 wt% bacterial cellulose hydrogel and 80-90 wt% aqueous polyurethane.
[0045] Furthermore, in step S2, the bacterial cellulose hydrogel is converted into an Acetobacter xylinum cellulose hydrogel.
[0046] Furthermore, in step S4, the foaming temperature is 120-150℃ and the time is 35-75s.
[0047] The third aspect of this application provides a polyurethane foam coated fabric, which is prepared using the preparation method described in the second aspect of this application.
[0048] The fourth aspect of this application provides a sports shoe, wherein the upper of the sports shoe is made of the polyurethane foam coated fabric described in the third aspect of this application.
[0049] The waterborne polyurethane in this embodiment is from Wanhua Chemical. The series of waterborne polyurethanes uses Dow Chemical's AMP-95 as the pH adjuster, BASF's Foamaster MO 2111 as the defoamer, and BASF as the wetting and dispersing agent. TA 240; the thickener is a BASF low-shear polyurethane thickener. PU 1193; the expanded microspheres were Expansion 043DU 80 from the Noron Group; Acetobacter xylinum was purchased from Nanjing Tianlu Nanotechnology Co., Ltd.
[0050] In this embodiment, the Acetobacter xylinum cellulose gel is prepared by the following method:
[0051] Fermentation preparation: Ferment with Acetobacter xylinum in a sugar-containing medium (glucose) to generate a gel-like BC membrane, and culture at 30-37℃ for 3-7 days.
[0052] Purification process: Boil with NaOH solution (5-10%) to remove residual bacterial cells and culture medium components, then wash repeatedly with deionized water until neutral to obtain pure BC hydrogel (initial water content >99%).
[0053] Pulverization: Pulverize the pure BC hydrogel using a high-speed blender with a speed of 20,000 to 30,000 rad / min for 1 minute.
[0054] Example 1: A polyurethane foam coated fabric
[0055] S1: Mix 83.3 parts by weight of waterborne polyurethane, 0.2 parts by weight of pH adjuster, 5 parts by weight of ethylene glycol, 0.5 parts by weight of defoamer, 2 parts by weight of wetting and dispersing agent, 0.8 parts by weight of thickener, 3.2 parts by weight of water, and 4 parts by weight of expanded microspheres to obtain waterborne polyurethane base material;
[0056] S2: Add 1 part by mass of bacterial cellulose hydrogel to the waterborne polyurethane base material, stir at 800-1000 rad / min for 10 min, and then seal and let stand at room temperature for 24-30 h to obtain polyurethane foam slurry.
[0057] S3: The polyurethane foam slurry is printed onto the surface of the base fabric by screen printing, and after drying, a fabric with a foam coating is obtained.
[0058] S4: Molding and foaming are performed using a foam coating at a temperature of 140-145℃ for 50 seconds to obtain the polyurethane foam coating fabric.
[0059] In Example 1, the viscosity of the polyurethane foam slurry was 145,000 cps, the foaming height was 2.15 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). No pinholes appeared on the coating surface.
[0060] Example 2: A polyurethane foam coated fabric
[0061] The difference between Example 2 and Example 1 is that the waterborne polyurethane is 83.5 parts by weight and the bacterial cellulose hydrogel is 0.8 parts by weight.
[0062] In Example 2, the viscosity of the polyurethane foam slurry was 139,000 cps, the foaming height was 2.17 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). No pinholes appeared on the coating surface.
[0063] Example 3: A polyurethane foam coated fabric
[0064] The difference between Example 3 and Example 1 is that the waterborne polyurethane is 83.7 parts by weight and the bacterial cellulose hydrogel is 0.6 parts by weight.
[0065] In Example 3, the viscosity of the polyurethane foam slurry was 131,000 cps, the foaming height was 2.18 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). No pinholes appeared on the coating surface.
[0066] Example 4: A polyurethane foam coated fabric
[0067] The difference between Example 4 and Example 1 is that the waterborne polyurethane is 83.9 parts by weight and the bacterial cellulose hydrogel is 0.4 parts by weight.
[0068] In Example 4, the viscosity of the polyurethane foam slurry was 125,000 cps, the foaming height was 2.18 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). No pinholes appeared on the coating surface.
[0069] Example 5 (50%) A polyurethane foam coated fabric
[0070] The difference between Example 5 and Example 1 is that the waterborne polyurethane is 83.6 parts by weight and the bacterial cellulose hydrogel is 0.7 parts by weight.
[0071] In Example 5, the viscosity of the polyurethane foam slurry was 136,000 cps, the foaming height was 2.18 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). No pinholes appeared on the coating surface.
[0072] Comparative Example 1
[0073] The difference between Comparative Example 1 and Example 1 is that the waterborne polyurethane is 84.3 parts by weight and the bacterial cellulose hydrogel is 0 parts by weight.
[0074] In Comparative Example 1, the viscosity of the polyurethane foam slurry was 120,000 cps, the foaming height was 2.19 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). Sand holes appeared on the coating surface.
[0075] Comparative Example 2
[0076] The difference between Comparative Example 2 and Example 1 is that the waterborne polyurethane is 83.1 parts by weight and the bacterial cellulose hydrogel is 1.2 parts by weight.
[0077] In Comparative Example 1, the viscosity of the polyurethane foam slurry was 152,000 cps, the foaming height was 2.16 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). No pinholes appeared on the coating surface.
[0078] Comparative Example 3
[0079] The difference between Comparative Example 3 and Example 1 is that the waterborne polyurethane is 84.1 parts by weight and the bacterial cellulose hydrogel is 0.2 parts by weight.
[0080] In Comparative Example 1, the viscosity of the polyurethane foam slurry was 120,000 cps, the foaming height was 2.18 mm, and the polyurethane foam coated fabric was resistant to high temperature and high humidity (tested according to the method specified in GB / T3903.7-2019). However, due to the low amount of bacterial cellulose hydrogel added, pinholes still appeared.
[0081] Finally, it should be noted that although the above embodiments have been described in the description of this application, this should not limit the scope of patent protection of this application. Any technical solutions that are based on the essential concept of this application, utilize the content described in this application's description to make equivalent structural or procedural substitutions or modifications, or directly or indirectly implement the technical solutions of the above embodiments in other related technical fields, are all included within the scope of patent protection of this application.
Claims
1. A water-based polyurethane slurry, characterized in that, The aqueous polyurethane slurry comprises 0.4-1 wt% bacterial cellulose hydrogel and 80-90 wt% aqueous polyurethane.
2. The waterborne polyurethane slurry according to claim 1, characterized in that, The bacterial cellulose hydrogel is an Acetobacter xylinum cellulose hydrogel.
3. The waterborne polyurethane slurry according to claim 1, characterized in that, The waterborne polyurethane slurry also contains a foaming agent and / or expanded microspheres.
4. The waterborne polyurethane slurry according to claim 1, characterized in that, The viscosity of the waterborne polyurethane slurry is 11,000-15,000 cps.
5. A method for preparing a polyurethane foam coated fabric, characterized in that, Includes the following steps: S1: Waterborne polyurethane, pH adjuster, ethylene glycol, defoamer, wetting and dispersing agent, thickener, water and expanding microspheres are mixed to obtain waterborne polyurethane base material; S2: Add bacterial cellulose hydrogel to waterborne polyurethane base material, stir at 800-1000 rad / min for 10 min, and then seal and let stand at room temperature for 24-30 h to obtain waterborne polyurethane foam slurry. S3: The polyurethane foam slurry is printed onto the surface of the base fabric by screen printing, and after drying, a fabric with a foam coating is obtained. S4: Foam the foam coating to obtain the polyurethane foam coated fabric.
6. The preparation method according to claim 5, characterized in that, In step S2, the aqueous polyurethane slurry comprises 0.4-1 wt% bacterial cellulose hydrogel and 80-90 wt% aqueous polyurethane.
7. The preparation method according to claim 5, characterized in that, In step S2, the bacterial cellulose hydrogel is converted into Acetobacter xylinum cellulose hydrogel.
8. The preparation method according to claim 5, characterized in that, In step S4, the foaming temperature is 120-150℃ and the foaming time is 35-75s.
9. A polyurethane foam coated fabric, characterized in that, The fabric is prepared using the preparation method described in any one of claims 5-8.
10. A type of athletic shoe, characterized in that, The upper of the athletic shoe is made of the polyurethane foam coated fabric as described in claim 9.