A polyurethane-based waterproof fabric and its preparation method

Abstract

This invention belongs to the field of fabric preparation technology, specifically disclosing a polyurethane-based waterproof fabric and its preparation method. The waterproof fabric is obtained by first treating a fabric substrate with plasma-enzyme composite treatment, and then coating the substrate with a polyurethane coating agent. The polyurethane coating agent, by mass percentage, comprises 25-35% waterborne polyurethane, 5-10% fumed nano-silica, 2-6% plant polysaccharides, 0.4-1.2% crosslinking agent, 0.4-0.6% thickener, and the balance being solvent. This invention alters the surface state of the fabric substrate by first treating it with plasma-enzyme composite treatment, reducing surface tension and increasing the permeability of the fabric fiber structure. The subsequent coating with the polyurethane coating agent yields a fabric with excellent water resistance, breathability, and moisture permeability, as well as good mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of fabric preparation technology, and particularly relates to a polyurethane-based waterproof fabric and its preparation method. Background Technology

[0002] Waterproof fabrics are common functional fabrics, capable of repelling rainwater while wicking away sweat, making them popular with consumers. Currently, waterproof properties are achieved through several methods, including direct coating, transfer coating, lamination, and wet coating.

[0003] Coating and lamination processes are the most common in the field of waterproof fabric preparation. Coating involves applying waterproof coatings to the fabric surface to give it waterproof properties. However, coating can affect the fabric's breathability, moisture permeability, and wearing comfort. Lamination, on the other hand, involves combining waterproof microporous membranes with fabrics (woven fabrics, knitted fabrics, non-woven fabrics, and functional fabrics) using lamination, printing, and other lamination techniques. In lamination, polyurethane microporous membranes are the most commonly used membrane material. Further improving the porosity and mechanical properties of polyurethane microporous membranes has a positive impact on the overall performance of waterproof fabrics. Summary of the Invention

[0004] To address the aforementioned problems, the primary objective of this invention is to provide a polyurethane-based waterproof fabric and its preparation method.

[0005] The specific technical solution of the present invention includes:

[0006] As a first aspect of the present invention, a polyurethane-based waterproof fabric is provided, wherein the waterproof fabric is obtained by first treating the fabric substrate with plasma composite enzyme, and then coating the fabric substrate with a polyurethane coating agent.

[0007] The polyurethane coating agent comprises, by weight percentage, 25-35% waterborne polyurethane, 5-10% fumed nano silica, 2-6% plant polysaccharides, 0.2-0.6% defoamer, 0.4-1.2% crosslinking agent, 0.4-0.6% thickener, and the balance being solvent.

[0008] As a further optimization of the present invention, the enzyme preparation used in the enzyme treatment is a neutral protease preparation or an alkaline protease preparation, and the amount used is 2-3% of the weight of the fabric substrate.

[0009] As a further optimization of the present invention, the fabric substrate is pure cotton fabric or a blended cotton fabric obtained by blending cotton fibers with polyester or nylon in equal mass ratios.

[0010] As a further optimization of the present invention, the method for preparing the polyurethane coating film includes the following steps:

[0011] (1) Dry the fumed nano silica to remove moisture, then mix it with ethanol, and after ultrasonic vibration, obtain a fumed nano silica solution for later use.

[0012] (2) Add waterborne polyurethane to a solvent and stir under heating conditions to dissolve completely to obtain a waterborne polyurethane solution. Add plant polysaccharide, defoamer, crosslinking agent and fumed silica solution obtained in step (1) to the waterborne polyurethane solution and stir under heating conditions to mix evenly. Then add thickener and stir evenly. Finally, the polyurethane coating agent can be obtained by vacuum degassing treatment.

[0013] As a second aspect of the present invention, a method for preparing a polyurethane-based waterproof fabric as described in any of the above-described steps is also provided, comprising the following steps:

[0014] (1) First, the fabric substrate is subjected to plasma treatment, and then the fabric substrate is subjected to enzyme treatment.

[0015] (2) Prepare a polyurethane coating agent according to the component ratio of the polyurethane coating agent, place the polyurethane coating agent in a mold for natural casting, and then place it in an oven to dry to obtain a polyurethane coating film.

[0016] (3) Use a printing machine to laminate the polyurethane coating film obtained in step (2) onto the fabric substrate obtained in step (1) to complete the single-sided coating treatment. Then, the fabric substrate that has undergone single-sided coating treatment is pre-baked and baked to obtain the waterproof fabric based on polyurethane.

[0017] As a further optimization of the present invention, the specific steps of step (1) include:

[0018] (1) Place the fabric substrate in a plasma treatment device and treat it for 40-60 seconds at 50-60V and 1.4-1.6kHz.

[0019] (2) At a temperature of 35-45℃, treat the fabric substrate treated in step (1) with an enzyme preparation for 30-50 minutes, then raise the temperature to 80-90℃ to deactivate the enzyme, and finally clean and dry the fabric substrate.

[0020] As a further optimization of the present invention, the pre-drying and baking process conditions in step (3) are: pre-drying at 80-100℃ for 3-6 minutes and baking at 140-160℃ for 1-2 minutes.

[0021] In summary, the beneficial effects of the present invention are as follows:

[0022] (1) The fabric substrate used in this invention is first treated with plasma composite enzyme. The surface of the fabric substrate is first etched by plasma to form free radicals on the fabric surface. Then, with enzyme treatment, the surface state of the fabric is changed, the surface tension is reduced, and the permeability of the fabric fiber structure is increased. Finally, after being combined with polyurethane coating agent, a fabric with excellent water resistance and breathability is obtained.

[0023] (2) The present invention incorporates plant polysaccharides into the components of the polyurethane coating agent. The plant polysaccharides replace conventional pore-forming agents, which not only further improves the porosity of the polyurethane coating film, but also enables the coating film to obtain better mechanical properties. As a result, when the coating film is laminated onto the fabric substrate, the fabric can be guaranteed to have good mechanical properties, thus improving the service life of the coated fabric. Detailed Implementation

[0024] The present application will now be described in further detail. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0025] Example 1

[0026] This embodiment provides a polyurethane-based waterproof fabric. The waterproof fabric is obtained by first treating the fabric substrate with plasma composite enzyme, and then coating the fabric substrate with a polyurethane coating agent. The fabric substrate is pure cotton fabric, and the enzyme preparation used for enzyme treatment is an alkaline protease preparation.

[0027] The polyurethane coating agent comprises, by mass percentage, 25% waterborne polyurethane, 10% fumed nano-silica, 2% plant polysaccharide, 0.4% crosslinking agent, and 0.6% thickener, with the remainder being solvent. In this embodiment, the plant polysaccharide is cellulose, the crosslinking agent is AF6900 crosslinking agent, the thickener is DN-2002 thickener, and the solvent is N-vinylpyrrolidone. The preparation method is as follows: after drying the fumed nano-silica to remove moisture, it is mixed with ethanol (mixing ratio is 1:10), and after ultrasonic vibration, a fumed nano-silica solution is obtained for later use; waterborne polyurethane is added to N-vinylpyrrolidone and stirred at 50°C until completely dissolved to obtain an waterborne polyurethane solution; plant polysaccharide, crosslinking agent, and the fumed silica solution obtained in step (1) are added to the waterborne polyurethane solution and stirred and mixed evenly at 50°C; then the thickener is added and stirred evenly; finally, the polyurethane coating agent is obtained by vacuum degassing treatment.

[0028] The method for preparing polyurethane-based waterproof fabric includes the following steps:

[0029] (1) First, place the fabric substrate in a plasma treatment device and treat it for 40 seconds at 50V and 1.6kHz. Then, treat the fabric substrate for 30 minutes at 35℃ using alkaline protease (2% of the weight of the fabric substrate) (bath ratio 40:1). Then, raise the temperature to 80℃ to deactivate the enzyme. Finally, clean the fabric substrate and air dry it.

[0030] (2) Prepare a polyurethane coating agent according to the component ratio of the polyurethane coating agent, place the polyurethane coating agent in a mold for natural casting, and then place it in an oven to dry to obtain a polyurethane coating film.

[0031] (3) The polyurethane coating film obtained in step (2) is laminated onto the fabric substrate obtained in step (1) using a printing machine to complete the single-sided coating treatment. Then, the fabric substrate that has undergone single-sided coating treatment is pre-baked and baked to obtain the polyurethane-based waterproof fabric. The pre-baking and baking process conditions are: pre-baking at 80℃ for 6 minutes and baking at 140℃ for 2 minutes.

[0032] Example 2

[0033] This embodiment provides a polyurethane-based waterproof fabric. The waterproof fabric is obtained by first treating the fabric substrate with plasma composite enzyme, and then coating the fabric substrate with a polyurethane coating agent. The fabric substrate is a cotton blend fabric obtained by blending cotton fiber and polyester in equal mass ratio.

[0034] The polyurethane coating agent comprises, by weight percentage, 35% waterborne polyurethane, 5% fumed nano silica, 6% plant polysaccharide, 1.2% crosslinking agent, and 0.4% thickener, with the remainder being solvent. In this embodiment, the plant polysaccharide is Jerusalem artichoke polysaccharide, the crosslinking agent is AF6900 crosslinking agent, the thickener is DN-2002 thickener, and the solvent is N-vinylpyrrolidone. The preparation method of the polyurethane coating agent is the same as in Example 1.

[0035] The method for preparing polyurethane-based waterproof fabric includes the following steps:

[0036] (1) First, place the fabric substrate in a plasma treatment device and treat it for 30 seconds at 60V and 1.4kHz. Then, treat the fabric substrate with alkaline protease (3% of the weight of the fabric substrate) for 50 minutes at a temperature of 45℃ (bath ratio 40:1). Then, raise the temperature to 90℃ to deactivate the enzyme. Finally, clean the fabric substrate and air dry it.

[0037] (2) Prepare a polyurethane coating agent according to the component ratio of the polyurethane coating agent, place the polyurethane coating agent in a mold for natural casting, and then place it in an oven to dry to obtain a polyurethane coating film.

[0038] (3) The polyurethane coating film obtained in step (2) is laminated onto the fabric substrate obtained in step (1) using a printing machine to complete the single-sided coating treatment. Then, the fabric substrate that has undergone single-sided coating treatment is pre-baked and baked to obtain the polyurethane-based waterproof fabric. The pre-baking and baking process conditions are: pre-baking at 100℃ for 3 minutes and baking at 160℃ for 1 minute.

[0039] Example 3

[0040] This embodiment provides a polyurethane-based waterproof fabric. The waterproof fabric is obtained by first treating the fabric substrate with plasma composite enzyme, and then coating the fabric substrate with a polyurethane coating agent. The fabric is a cotton blend fabric obtained by blending cotton fiber and nylon in an equal mass ratio.

[0041] The polyurethane coating agent comprises, by weight percentage, 30% waterborne polyurethane, 7% fumed nano silica, 4% plant polysaccharide, 0.8% crosslinking agent, 0.5% thickener, and the remainder is solvent. In this embodiment, the plant polysaccharide is an equal mass ratio of Jerusalem artichoke polysaccharide and cellulose, the crosslinking agent is AF6900 crosslinking agent, the thickener is DN-2002 thickener, and the solvent is N-vinylpyrrolidone. The preparation method of the polyurethane coating agent is the same as in Example 1.

[0042] The method for preparing polyurethane-based waterproof fabric includes the following steps:

[0043] (1) First, place the fabric substrate in a plasma treatment device and treat it for 30 seconds at 60V and 1.4kHz. Then, treat the fabric substrate with alkaline protease (3% of the weight of the fabric substrate) for 50 minutes at a temperature of 45℃ (bath ratio 40:1). Then, raise the temperature to 90℃ to deactivate the enzyme. Finally, clean the fabric substrate and air dry it.

[0044] (2) Prepare a polyurethane coating agent according to the component ratio of the polyurethane coating agent, place the polyurethane coating agent in a mold for natural casting, and then place it in an oven to dry to obtain a polyurethane coating film.

[0045] (3) The polyurethane coating film obtained in step (2) is laminated onto the fabric substrate obtained in step (1) using a printing machine to complete the single-sided coating treatment. Then, the fabric substrate that has undergone single-sided coating treatment is pre-baked and baked to obtain the polyurethane-based waterproof fabric. The pre-baking and baking process conditions are: pre-baking at 100℃ for 3 minutes and baking at 160℃ for 1 minute.

[0046] Comparative Example 1

[0047] This comparative example provides a polyurethane-based waterproof fabric, which differs from Example 1 in that step (1) of its preparation method only involves plasma treatment of the fabric substrate and does not involve enzyme treatment.

[0048] Comparative Example 2

[0049] This comparative example provides a polyurethane-based waterproof fabric, which differs from Example 1 in that step (1) of its preparation method only involves enzymatic treatment of the fabric substrate and does not involve plasma treatment.

[0050] Comparative Example 3

[0051] This comparative example provides a polyurethane-based waterproof fabric, which differs from Example 1 in that its preparation method involves first enzymatically treating the fabric substrate in step 1, and then plasma treating the fabric substrate.

[0052] Comparative Example 4

[0053] This comparative example provides a polyurethane-based waterproof fabric, which differs from Example 1 in that the enzyme preparation used is a neutral protease preparation, and the amount used is 2% of the weight of the fabric substrate.

[0054] Comparative Example 5

[0055] This comparative example provides a polyurethane-based waterproof fabric. The difference from Example 1 is that in its preparation method, step (1) involves pretreating the fabric substrate with a water-repellent finishing liquid, without plasma-enzyme treatment. Specifically, an appropriate amount of commercially available water-repellent finishing agent is taken, diluted with deionized water to a mass concentration of 13 g / L, and stirred evenly. The washed and naturally dried fabric is immersed in the emulsion for 10 minutes, then subjected to two dips and two nips (controlling the nip-off rate to 70%), pre-dried at 100°C for 3 minutes, and then baked at 150°C for 1 minute to obtain the water-repellent pretreated cotton fabric.

[0056] Verification test

[0057] 1. The fabric samples obtained in Example 1 and Comparative Examples 1-5 were tested for contact angle, hydrostatic pressure resistance and air permeability.

[0058] Contact angle test: According to DB44T 1872—2016 "Determination of surface wetting properties of textiles - Contact angle method", a 5 μL volume of deionized water was dropped onto the sample surface and allowed to stand for 30 seconds. The contact angle was calculated using a five-point fitting method. Five different locations were tested for each sample, and the average value was taken.

[0059] Hydrostatic pressure resistance test: The direct pressurization method is used. The fabric is placed on the test clamp and the pressure is continuously increased at a rate of 6 kPa / min. When water seeps into the fabric surface at 3 points, the pressure value is recorded.

[0060] Air permeability test: Referring to the national standard (GB / T5433), the air permeability of the samples was tested using a YG461G fully automatic fabric air permeability meter. Specific experimental parameters were set as follows: ambient temperature 25℃, relative humidity 60%, pressure difference 100Pa, and air permeability area 20cm². 2 The nozzle diameter is 0.8mm. Ten tests were conducted on different parts of the fabric sample, and the average value was taken as the final air permeability data.

[0061] Moisture permeability test: The moisture permeability of the samples was tested using an FX3180 moisture permeability meter according to national standard GB / T12704.1-2009(a). During the test, the temperature was 38℃, the humidity was 90.0%, the airflow velocity was 0.5 m / s, and the test area was 28.3 cm². 2 Before testing, the test chamber needs to be pre-conditioned for humidity. After automatic humidity conditioning, the instrument begins the moisture permeability test, automatically recording moisture permeability data every hour for a total of two times. After the experiment is completed, the moisture permeability data of the samples are manually recorded, and the average of 10 sets of experimental data for each sample is used as the final data.

[0062] The results are shown in Table 1.

[0063] Table 1. Statistical Table of Test Results

[0064]

[0065] As can be seen from Table 1, the fabric prepared in Example 1 is superior to the other comparative examples 1-5 in terms of waterproofness and breathability. In particular, the breathability of Example 1 is significantly better than that of comparative examples 1-4. It can be seen that plasma composite enzyme treatment of fabric substrate, in which the electrons, atoms, and ions of plasma etch the fabric surface to form free radicals, combined with enzyme treatment, can improve the breathability and moisture permeability of the fabric to a certain extent. In addition, the data comparison between comparative example 4 and example 1 shows that in the enzyme treatment step, the use of alkaline protease is better than that of neutral protease in improving the breathability of the fabric.

[0066] II. To investigate the effect of the incorporation of plant polysaccharides in polyurethane coating agents on fabric performance, the composition of polyurethane coating agents was adjusted according to the selection of plant polysaccharide types given in Table 2. The remaining components were the same as in Example 1. Fabric AE was prepared according to the preparation method given in Example 1. The air permeability, moisture permeability and water resistance of the fabric were tested, and the results are shown in Table 3.

[0067] Table 2. Selection of Plant Polysaccharide Types

[0068]

[0069]

[0070] Table 3. Statistical Table of Test Results

[0071]

[0072] As shown in Table 3, compared with group DE, the polyurethane coating agent incorporating plant polysaccharides in group AC improved the breathability and moisture permeability of the fabric to a certain extent, without weakening the water resistance of the fabric. The data comparison of group AC shows that the combination of cellulose and Jerusalem artichoke polysaccharides in an equal weight ratio has a better effect on improving the breathability and moisture permeability of the fabric than using cellulose or Jerusalem artichoke polysaccharides alone. This is because the use of cellulose and Jerusalem artichoke polysaccharides has a positive impact on improving the porosity of the polyurethane coating film.

[0073] To further investigate the effect of plant polysaccharides in the polyurethane coating agent on the performance of the polyurethane coated film, the composition of the polyurethane coating agent was adjusted according to the selection of plant polysaccharide types given in Table 2. The remaining components were the same as in Example 1. Then, according to the preparation method of the polyurethane coating agent and the preparation method of the polyurethane coated film disclosed in Example 1, film samples 1-5 were prepared. The porosity and mechanical properties of film samples 1-5 were tested as follows:

[0074] (1) Porosity test: A certain mass of membrane sample (dried to constant weight) is soaked in anhydrous ethanol for 24 hours. After taking it out, the ethanol adsorbed on the surface is gently absorbed with filter paper, and the sample is weighed quickly. The porosity of the membrane sample is calculated according to the following formula.

[0075]

[0076] In the formula, w1 and w2 are the masses of the film sample before and after soaking, respectively, in grams; ρ1 is the density of the film sample, in g / cm³. 3 ρ2 is the density of anhydrous ethanol, in g / cm³. 3 .

[0077] (1) Mechanical property test: Take film samples with consistent size and thickness and store them under constant temperature and humidity for 24 hours. Use a microcomputer-controlled electronic universal testing machine to test the mechanical properties of different film samples when stretched to breakage. Five film samples are tested in each group, and the average value of the test results is taken. The stretching rate is 50 mm / min. The test method refers to GB / T1040-1992.

[0078] The test results of porosity and mechanical properties are shown in Table 4.

[0079] Table 4. Test results of porosity and mechanical properties of polyurethane coated films.

[0080]

[0081] As can be seen from Table 4, the use of plant polysaccharides is more effective than traditional pore-forming agents (polyethylene glycol, ammonium bicarbonate) in improving the porosity of polyurethane coating films. This is also the reason why fabric C has better air permeability and moisture permeability than other fabrics. Furthermore, comparing the data of film samples 1-3 shows that the combined use of cellulose and Jerusalem artichoke polysaccharides is more effective than using cellulose and Jerusalem artichoke polysaccharides alone.

[0082] The mechanical properties of polyurethane coating films with added traditional pore-forming agents are inferior to those with added plant polysaccharides. Composite polyurethane coating films with added plant polysaccharides onto fabric substrates can ensure that the fabric has better mechanical properties. In addition, as can be seen from the table, the mechanical properties of the film samples made by using cellulose or Jerusalem artichoke polysaccharides alone are better than those prepared by using a combination of cellulose and Jerusalem artichoke polysaccharides, but the difference is not significant. From the perspective of improving the breathability and moisture permeability of fabrics, the plant polysaccharides should be selected by using a combination of cellulose and Jerusalem artichoke polysaccharides.

[0083] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various improvements without departing from the concept of the present invention, and these improvements all fall within the scope of protection of the present invention.

Claims

1. A waterproof fabric based on polyurethane, characterized in that, The waterproof fabric is obtained by first subjecting the fabric substrate to a sequential composite treatment of plasma followed by enzyme, and then applying a polyurethane coating agent onto the fabric substrate that has undergone the sequential composite treatment of plasma followed by enzyme. The polyurethane coating agent comprises, by weight percentage, 25-35% waterborne polyurethane, 5-10% fumed nano silica, 2-6% plant polysaccharide, 0.4-1.2% crosslinking agent, 0.4-0.6% thickener, and the balance being solvent; wherein the plant polysaccharide is a compound of cellulose and Jerusalem artichoke polysaccharide in equal weight ratio.

2. The polyurethane-based waterproof fabric according to claim 1, characterized in that, The enzyme preparation used in the enzyme treatment is a neutral protease preparation or an alkaline protease preparation, and the amount used is 2-3% of the weight of the fabric substrate.

3. The polyurethane-based waterproof fabric according to claim 1, characterized in that, The fabric substrate is pure cotton fabric or a blended cotton fabric obtained by blending cotton fiber with polyester or nylon in equal mass ratio.

4. The polyurethane-based waterproof fabric according to claim 1, characterized in that, The preparation method of the polyurethane coating agent includes the following steps: (1) After drying the fumed nano silica to remove moisture, mix it with ethanol, and then sonicate to obtain a fumed nano silica solution for later use. (2) Add waterborne polyurethane to the solvent and stir under heating conditions to dissolve completely to obtain waterborne polyurethane solution. Add plant polysaccharide, crosslinking agent and fumed silica solution obtained in step (1) to the waterborne polyurethane solution and stir under heating conditions to mix evenly. Then add thickener and stir evenly. Finally, the polyurethane coating agent can be obtained by vacuum degassing treatment.

5. A method for preparing a polyurethane-based waterproof fabric as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) First, the fabric substrate is subjected to plasma treatment, and then the fabric substrate is subjected to enzyme treatment; (2) Prepare a polyurethane coating agent according to the component ratio of the polyurethane coating agent, place the polyurethane coating agent in a mold for natural casting, and then place it in an oven to dry to obtain a polyurethane coating film. (3) The polyurethane coating film obtained in step (2) is laminated onto the fabric substrate obtained in step (1) using a printing machine to complete the single-sided coating treatment. Then, the fabric substrate that has undergone single-sided coating treatment is pre-baked and baked to obtain the polyurethane-based waterproof fabric.

6. The method for preparing a polyurethane-based waterproof fabric according to claim 5, characterized in that, The specific steps of step (1) include: (1) Place the fabric substrate in a plasma treatment device and treat it for 40-60 seconds at 50-60V and 1.4-1.6kHz. (2) At a temperature of 35-45℃, treat the fabric substrate treated in step (1) with an enzyme preparation for 30-50 minutes. Then, raise the temperature to 80-90℃ to deactivate the enzyme. Finally, clean the fabric substrate and air dry it.

7. The method for preparing a polyurethane-based waterproof fabric according to claim 5, characterized in that, The pre-drying and baking process conditions in step (3) are: pre-drying at 80-100℃ for 3-6 minutes and baking at 140-160℃ for 1-2 minutes.

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