Preparation method of super-hydrophobic polyester fabric

Abstract

The invention relates to the field of waterproof fabric manufacturing, in particular to a super-hydrophobic polyester fabric preparation method which specifically comprises the following steps: adding nano aluminum oxide into an acid solution, and sequentially stirring, washing and drying to obtain surface-passivated aluminum oxide powder; sequentially adding a hydrogen polymethylsiloxane solution, surface-passivated aluminum oxide powder, a silane coupling agent and PU resin into a DMF (Dimethyl Formamide) solvent, and stirring in the whole process to obtain a coating solution; dipping the polyester fabric in the coating liquid, carrying out ultrasonic treatment, and then drying and cooling; the fabric is subjected to ultraviolet curing and then cooled, hydroxyl groups on the surface of aluminum oxide are neutralized to be removed as much as possible so as to reduce subsequent consumption of Si-H functional groups, and a silane coupling agent can improve interface bonding force among the aluminum oxide, hydrogen polymethylsiloxane and PU resin, so that a coating is not prone to falling off.

Description

TECHNICAL FIELD

[0001] The application relates to the field of waterproof fabric manufacturing, in particular to a super-hydrophobic polyester fabric preparation method. BACKGROUND

[0002] Polyester is a commonly used fabric material, but polyester itself cannot be waterproof, and some products such as jackets and tarpaulins have certain requirements for waterproofness. In order to make polyester fabric have waterproof effect, corresponding waterproof agent needs to be coated on the surface of the fabric, generally some low surface energy substances such as silane activators, but the coating formed by silane activators is easy to fall off in a long time of use.

[0003] Therefore, some auxiliary substances are added to the silane activator on the surface of the fabric to make the coating not easy to fall off. For example, a preparation method of a waterproof and oil-repellent jacket made of waterproof and oil-repellent fabric is disclosed in CN119041220A, in which nano-aluminum oxide is mixed with a hydrogen polysiloxane solution, and then the base fabric is soaked. After the base fabric is soaked, a mixed solution of PU resin, hydrogen polysiloxane solution and metal catalyst is sprayed. Nano-aluminum oxide and PU resin can tightly support the hydrogen polysiloxane.

[0004] In the above-mentioned related technology, the surface of aluminum oxide contains basic hydroxyl groups, and Si-H bonds exist in the hydrogen polysiloxane molecules. The Si-H bonds and the basic hydroxyl groups will slowly undergo a dehydrogenation reaction, causing the Si-H functional groups in the hydrogen polysiloxane solution to be consumed, inhibiting the cross-linking and curing reaction involving Si-H functional groups, and weakening the adhesion of the coating. SUMMARY

[0005] In order to make the adhesion of the coating not easy to be affected, the application provides a super-hydrophobic polyester fabric preparation method.

[0006] The super-hydrophobic polyester fabric preparation method provided by the application adopts the following technical scheme.

[0007] A super-hydrophobic polyester fabric preparation method, specifically comprising the following steps.

[0008] Step one, adding nano-aluminum oxide to an acid solution and sequentially stirring, washing and drying to obtain surface-passivated aluminum oxide powder; Step two, sequentially adding hydrogen polysiloxane solution, surface-passivated aluminum oxide powder, silane coupling agent and PU resin in a DMF solvent, and stirring throughout to obtain a coating solution; Step three, immersing the polyester fabric in the coating solution and performing ultrasonic treatment, and then drying and cooling; Step four, ultraviolet curing the fabric and then cooling.

[0009] By adopting the technical scheme, the hydroxyl groups on the surface of the alumina are neutralized to remove as much as possible to reduce the consumption of the subsequent Si-H functional groups, and the silane coupling agent can improve the interfacial bonding force between the alumina, the hydrogen polymethylsiloxane and the PU resin, so that the coating is not easy to fall off.

[0010] Optionally, the acid solution includes any one of a citric acid aqueous solution, a maleic acid aqueous solution and a tartaric acid aqueous solution.

[0011] Optionally, the acid solution is a citric acid aqueous solution with a concentration of 0.5%-3%.

[0012] Optionally, the concentration of the citric acid aqueous solution is 1%.

[0013] By adopting the technical scheme, the citric acid is relatively mild and controllable, and is not easy to cause severe corrosion of the surface structure of the alumina. Meanwhile, the citric acid can effectively remove impurities on the surface of the alumina. The alumina treated by the citric acid has excellent dispersibility in the DMF solvent, which helps to improve the stability and uniformity of the coating. The concentration of the citric acid aqueous solution is limited to prevent the alumina particles from easily gathering due to poor modification effect of the alumina surface caused by too low concentration of the citric acid aqueous solution, so that the coating liquid is not stable and easily precipitates. The concentration of the citric acid aqueous solution is also limited to prevent the surface structure of the nano-alumina particles from being excessively corroded and damaged due to too high concentration of the citric acid aqueous solution, so as to affect the adhesion of the subsequent coating.

[0014] Optionally, the PDMS-b-PCL block copolymer is added after the PU resin is added in the second step.

[0015] By adopting the technical scheme, a transition layer is formed between the PU resin and the hydrogen polymethylsiloxane to enhance the mutual solubility of the PU resin and the hydrogen polymethylsiloxane in the DMF solution, so as to further improve the uniformity of the coating and help to improve the adhesion of the coating.

[0016] Optionally, the photoinitiator and the ultraviolet absorber are added after the PDMS-b-PCL block copolymer is added in the second step, and the wavelength of the ultraviolet light in the fourth step is 200-280 nm.

[0017] By adopting the technical scheme, the short-wave ultraviolet light is selected and combined with the photoinitiator to selectively excite the cross-linking reaction, avoid non-selective degradation, and as much as possible reduce photochemical reactions of ester bonds and aromatic amine groups. In addition, the ultraviolet absorber is combined to reduce the degradation of the coating structure under long-term light.

[0018] Optionally, the photoinitiator includes any one of 1-hydroxycyclohexyl phenyl ketone, benzoin dimethyl ketal and camphorquinone.

[0019] Optionally, the ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone or 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

[0020] By adopting the technical scheme, the light initiator and the ultraviolet absorber are selected according to needs.

[0021] Optionally, the step three is performed by intermittent ultrasonic treatment, 5 min each time, repeated 6 times, and the ultrasonic treatment is spaced 5 min each time.

[0022] By adopting the technical scheme, the local temperature is prevented from being too high due to long-time ultrasonic treatment, so that the solvent is prevented from being excessively volatilized or prematurely cross-linked, the alumina particles are stably dispersed in the interval time between two ultrasonic treatments, the micro-bubbles are timely escaped, and the possibility of coating hole defects is reduced.

[0023] Optionally, the step three is performed by intermittent ultrasonic treatment, 5 min each time, repeated 6 times, and the ultrasonic treatment is spaced 5 min each time.

[0024] By adopting the technical scheme, the bonding strength between the coating and the fabric is further improved, and the coating is more difficult to fall off.

[0025] In summary, the present application at least includes the following beneficial effects.

[0026] 1. The hydroxyl groups on the surface of alumina are neutralized to remove as many as possible to reduce the consumption of subsequent Si-H functional groups, and the silane coupling agent can improve the interfacial bonding force between alumina, hydrogen polymethylsiloxane and PU resin; 2. The addition of PDMS-b-PCL block copolymer can form a transition layer between PU resin and hydrogen polymethylsiloxane, enhance the mutual solubility of PU resin and hydrogen polymethylsiloxane in DMF solution, and further improve the uniformity of the coating, which is helpful to improve the adhesion of the coating; 3. Selective excitation of cross-linking reaction is performed by selecting short-wave ultraviolet light and cooperating with a light initiator to avoid non-selective degradation, as much as possible to reduce photochemical reactions of ester bonds and aromatic amine groups, and to avoid yellowing or embrittlement of some aromatic components in PU resin under medium-wave ultraviolet light, and in addition, an ultraviolet absorber is combined to reduce the degradation of the coating structure under long-term light. 4. The intermittent ultrasonic treatment can avoid long-time ultrasonic treatment leading to too high local temperature, so that the solvent is prevented from being excessively volatilized or prematurely cross-linked, the alumina particles are stably dispersed in the interval time between two ultrasonic treatments, the micro-bubbles are timely escaped, and the possibility of coating hole defects is reduced. DETAILED DESCRIPTION

[0027] The present application discloses a method for preparing a super-hydrophobic polyester fabric, which specifically comprises the following steps.

[0028] Step one, add nano-alumina to the acid solution, stir at 60°C for 2h, centrifugal washing 3 times, remove the residual acid solution, then dry at 100°C, obtain surface passivated alumina powder.

[0029] Among them, the acid solution includes any one of citric acid aqueous solution, maleic acid aqueous solution and tartaric acid aqueous solution, and the acid solution is preferably 0.5%-3% citric acid aqueous solution.

[0030] Step two, pour DMF solvent into the reaction kettle and keep 50-60°C. First, slowly add the hydrogen polymethylsiloxane solution and stir until completely dissolved. Then add the surface passivated alumina powder and stir at high speed of 3000 rpm for 30 min. Then add the silane coupling agent and stir for 10 min. Then slowly add the PU resin and stir until a transparent / half-transparent uniform system is formed. Then add the PDMS-b-PCL block copolymer and stir. Finally, add the photoinitiator and ultraviolet absorber and stir, and test the viscosity to ensure that the solution viscosity is 1500-2500 cps to obtain the coating liquid.

[0031] Among them, the photoinitiator includes any one of 1-hydroxycyclohexyl phenyl ketone, benzoin dimethyl ketal and camphorquinone, and the ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone or 2-(2'-hydroxy-5'-methylphenyl) benzotriazole.

[0032] Step three, first ultrasonic cleaning of the polyester fabric, then plasma treatment with power 200w for 60s. Then immerse the polyester fabric in the coating liquid and perform intermittent ultrasonic treatment with a frequency of 70kHz, 5min each time, repeat 6 times, with 5min interval between each ultrasonic treatment, then dry and cool.

[0033] Step four, irradiate the coating with a UV-C lamp with a wavelength of 200-280nm to ultraviolet cure the fabric and then cool to room temperature.

[0034] The following is specifically described with several examples and comparative examples. Example

[0035] Step one, add nano-alumina to 1% concentration of citric acid aqueous solution, stir at 60°C for 2h, centrifugal washing 3 times, remove the residual acid solution, then dry at 100°C, obtain surface passivated alumina powder.

[0036] Step two, pour DMF solvent into the reaction kettle and keep 55°C. Slowly add the hydrogen polydimethylsiloxane solution first and stir until completely dissolved. Then add the surface passivated alumina powder and stir at high speed of 3000 rpm for 30 min. Then add the silane coupling agent and stir for 10 min. Slowly add the PU resin and stir until a transparent / semi-transparent uniform system is formed. Then add the PDMS-b-PCL block copolymer and stir. Finally, add 1-hydroxy cyclohexyl phenyl ketone and 2-hydroxy-4-n-octyloxy benzophenone and stir, and test the viscosity to ensure that the solution viscosity is 1500-2500 cps to obtain the coating liquid.

[0037] Step three, the polyester fabric is first ultrasonically cleaned, then plasma treated at a power of 200w for 60s. Then the polyester fabric is immersed in the coating liquid and subjected to intermittent ultrasonic treatment at a frequency of 70 kHz for 5 min each time, repeated 6 times, with a 5 min interval between each ultrasonic treatment, and then dried and cooled.

[0038] Step four, the coating is irradiated with a UV-C lamp with a wavelength of 250 nm to cure the fabric with ultraviolet light and then cooled to room temperature. Example

[0039] The difference between Example 1 and this example is that the concentration of the aqueous citric acid solution is 0.5%. Example

[0040] The difference between Example 1 and this example is that the concentration of the aqueous citric acid solution is 3%. Example

[0041] The difference between Example 1 and this example is that the acid solution is a 1% concentration aqueous tartaric acid solution. Example

[0042] The difference between Example 1 and this example is that the photoinitiator is benzoin dimethyl ketal and the ultraviolet absorber is 2-(2'-hydroxy-5'-methylphenyl) benzotriazole. Example

[0043] The difference between Example 1 and this example is that the ultraviolet light wavelength in step four is 200 nm. Example

[0044] The difference between Example 1 and this example is that the ultraviolet light wavelength in step four is 280 nm.

[0045] Comparative Example 1: The difference between Example 1 and this example is that the concentration of the aqueous citric acid solution is 0.2%.

[0046] Comparative Example 2: The difference between Example 1 and this example is that the concentration of the aqueous citric acid solution is 5%.

[0047] Comparative Example 3: The difference between Example 1 and Comparative Example 3 is that Step 1 is not performed.

[0048] Comparative Example 4: The difference between Example 1 and Comparative Example 4 is that PDMS-b-PCL block copolymer is not added in Step 2.

[0049] Comparative Example 5: The difference between Example 1 and Comparative Example 5 is that photoinitiator and ultraviolet absorber are not added, and the wavelength of ultraviolet light is 300 nm.

[0050] Comparative Example 6: The difference between Example 1 and Comparative Example 6 is that the ultrasonic duration in Step 3 is 30 min without interruption.

[0051] After obtaining the samples of the above examples and comparative examples, the following indicators are measured.

[0052] Contact angle: The contact angle is measured using an optical contact angle measuring instrument according to the standard ASTM D7334-08. The larger the contact angle, the better the water resistance of the fabric.

[0053] Peeling strength: The peeling strength is measured using a tensile testing machine according to the standard GB / T 5210-2006. The larger the peeling strength, the greater the adhesion of the coating and the less likely it is to fall off.

[0054] Grid rating: The grid rating is measured according to the standard GB / T 9286-1998. The grid rating is divided into 0-5 levels, with 0 indicating that the coating is intact, and 5 indicating that the peeling degree is serious.

[0055] The experimental results are shown in the following table.

[0056]

[0057] From Examples 1-3 and Comparative Examples 1-3, it can be seen that the addition of acid solutions such as citric acid can effectively improve the cross-linking stability between the components in the coating, thereby improving the adhesion and water resistance of the coating. Citric acid has advantages in terms of price and safety, and the fabric prepared using 0.5%-3% citric acid has better performance.

[0058] From Examples 1-7 and Comparative Example 4, it can be seen that the addition of PDMS-b-PCL block copolymer can effectively improve the mutual solubility of PU resin and hydrogen polydimethylsiloxane in DMF solution, thereby further improving the uniformity of the coating and helping to improve the adhesion and water resistance of the coating.

[0059] As can be seen from Examples 1, 6 and 7 and Comparative Example 5, the use of short-wave ultraviolet light in combination with a photoinitiator to selectively excite the crosslinking reaction can improve the coating quality by avoiding the non-selective degradation caused by strong medium-wave ultraviolet light.

[0060] As can be seen from Examples 1 to 7 and Comparative Example 6, intermittent ultrasonic treatment can avoid excessive local temperature caused by long-time ultrasonic treatment, thereby preventing excessive solvent evaporation or premature crosslinking, and can also stabilize the dispersion of aluminum oxide particles during the interval between two ultrasonic treatments, and can also make microbubbles escape in time, which is helpful to improve the coating quality.

[0061] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for preparing a superhydrophobic polyester fabric, characterized in that: Specifically, the following steps are included: Step 1: Add nano-alumina to an acid solution and stir, wash and dry in sequence to obtain surface-passivated alumina powder; Step 2: Add hydrogen polymethylsiloxane solution, surface passivated alumina powder, silane coupling agent and PU resin to DMF solvent in sequence, stirring throughout the process to obtain coating solution; Step 3: Immerse the polyester fabric in the coating solution and perform ultrasonic treatment, then dry and cool; Step 4: Cure the fabric with ultraviolet light and then cool it.

2. The method for preparing a superhydrophobic polyester fabric according to claim 1, characterized in that: The acid solution includes any one of citric acid aqueous solution, maleic acid aqueous solution, and tartaric acid aqueous solution.

3. The method for preparing a superhydrophobic polyester fabric according to claim 2, characterized in that: The acid solution is a citric acid aqueous solution with a concentration of 0.5%-3%.

4. The method for preparing a superhydrophobic polyester fabric according to claim 3, characterized in that: The concentration of the citric acid aqueous solution is 1%.

5. The method for preparing a superhydrophobic polyester fabric according to claim 1, characterized in that: In step two, PDMS-b-PCL block copolymer is added after PU resin.

6. The method for preparing a superhydrophobic polyester fabric according to claim 5, characterized in that: In step two, after adding the PDMS-b-PCL block copolymer, a photoinitiator and an ultraviolet absorber are added, and in step four, the ultraviolet wavelength is 200-280nm.

7. The method for preparing a superhydrophobic polyester fabric according to claim 6, characterized in that: The photoinitiator includes any one of 1-hydroxycyclohexylphenyl ketone, benzoyl dithionate, and camphorquinone.

8. The method for preparing a superhydrophobic polyester fabric according to claim 6, characterized in that: The ultraviolet absorber is 2-hydroxy-4-n-octyloxybenzophenone or 2-(2'-hydroxy-5'-methylphenyl)benzotriazole.

9. The method for preparing a superhydrophobic polyester fabric according to claim 1, characterized in that: Step three involves intermittent ultrasound treatment, each lasting 5 minutes, repeated 6 times, with a 5-minute interval between each ultrasound session.

10. The method for preparing a superhydrophobic polyester fabric according to claim 1, characterized in that: In step three, the polyester fabric undergoes ultrasonic cleaning and plasma treatment before being immersed in the coating solution.

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