ANTI-FOULING POLYURETHANE THIN FILM WITH HIGH ELASTICITY AND HIGH TRANSPARENCY, PREPARATION METHOD AND USE THEREOF

Abstract

The invention discloses an anti-fouling polyurethane thin film with high elasticity and high transparency, a preparation method and use thereof. The raw materials of the polyurethane thin film include the following active ingredients by mass fractions: 30% to 40% of a hard segment monomer, 40% to 50% of a soft segment monomer, 3% to 6% of a hydrophilic monomer, 0% to 3% of a crosslinking monomer, 0% to 5% of a small molecular chain extender, and 10% to 15% of a compound with low surface energy. A chemically and physically double-crosslinked anti-fouling polyurethane is synthesized through a polycondensation reaction. This thin film exhibits superior low adhesion and anti-fouling properties, and can achieve the coexistence of both low adhesion and stretchability at the same time.

Claims

1. An anti-fouling polyurethane thin film with high elasticity and high transparency, characterized in that, its raw materials for preparation comprises the following active ingredients by mass fractions: TABLE-US-00004 a hard segment monomer 30% to 40%; a soft segment monomer 40% to 50%; a hydrophilic monomer 3% to 6%; a crosslinking monomer 0% to 3%; a small molecular chain extender 0% to 5%; and a compound with low surface energy 10% to 15%, wherein the mass fraction refers to the mass fraction of each active ingredient in the total active ingredients.

2. The anti-fouling polyurethane thin film with high elasticity and high transparency according to claim 1, characterized in that, the hard segment monomer is at least one of toluene-2,4-diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, 1,4-cyclohexane diisocyanate and isophorone diisocyanate; the soft segment monomer is at least one of polyester glycol and polyether glycol; the hydrophilic monomer is at least one of sodium 1,4-butanediol-2-sulfonate, sodium 1,2-propanediol-3-sulfonate, sodium ethylenediamino ethanesulfonate, 2,4-diamino benzenesulfonic acid, dimethylol propionic acid and dimethylol butyric acid; the crosslinking monomer is at least one of glycerol, triisopropanolamine, pentaerythritol, and trimethylolpropane; the small molecular chain extender is at least one of 1,4-butanediol, ethylene glycol, diethylene glycol, and ethylene diamine; and the compound with low surface energy is a monohydroxyalkyl organic fluorine.

3. The anti-fouling polyurethane thin film with high elasticity and high transparency according to claim 1, characterized in that, the hard segment monomer is isophorone diisocyanate; the soft segment monomer is at least one of polytetrahydrofuran ether glycol, and poly(adipic acid)-(2-methyl-1,3-propanediol)-(1,4-butanediol) ester diols; the hydrophilic monomer is dimethylol butyric acid; the crosslinking monomer is trimethylol propane; the small molecular chain extender is at least one of 1,4-butanediol and ethylene glycol; and the compound with low surface energy is at least one of 3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluoro-1-octanol, 1H, 1H, 9H-hexadecafluoro-1-nonanol, and 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluoro-1-octanol.

4. The anti-fouling polyurethane thin film with high elasticity and high transparency according to claim 1, characterized in that, the raw materials for preparation further include a catalyst, and the catalyst is dibutyl tin dilaurate catalyst, the amount of which is 0% to 0.05% of the total mass of the active ingredients in the raw materials for preparation.

5. A method for preparing the anti-fouling polyurethane thin film with high elasticity and high transparency according to claim 1, characterized in that, it includes the following steps: (1) mixing a soft segment monomer, a hydrophilic monomer and a crosslinking monomer uniformly, adding a hard segment monomer and a catalyst under stirring condition, heating to 70 to 85° C., reacting for 2 to 5 hours, adding the compound with low surface energy, and continuing to react for 2 to 5 hours, to obtain a prepolymer; (2) cooling the obtained prepolymer, adding triethylamine to neutralize the prepolymer, and adding water to disperse and emulsify the obtained prepolymer; after the prepolymer is dispersed and emulsified by water, adding the small molecular chain extender for chain extension, to obtain a polyurethane aqueous dispersion; and (3) curing the obtained polyurethane aqueous dispersion, to obtain the anti-fouling polyurethane thin film with high elasticity and high transparency.

6. The method for preparing the anti-fouling polyurethane thin film with high elasticity and high transparency according to claim 5, characterized in that, the chain extension in step (2) refers to reacting at room temperature for 0.5 to 2 hours for chain extension;

7. The method for preparing the anti-fouling polyurethane thin film with high elasticity and high transparency according to claim 5, characterized in that, the solid content of the polyurethane aqueous dispersion in step (2) is 20% to 40%; and the curing in step (3) refers to baking at 20 to 90° C. for 1 to 24 hours.

8. Use of the anti-fouling polyurethane thin film with highly elasticity and high transparency according to claim 1 as a self-cleaning coating layer of surface for a substrate.

9. The use of the anti-fouling polyurethane thin film with highly elasticity and high transparency according to claim 8, characterized in that, the substrate is glass, wood, metal, ceramics, leather, or polymer substrate.

10. Use of the anti-fouling polyurethane thin film with highly elasticity and high transparency according to claim 1 as a self-cleaning coating layer for flexible electronic display screen and wearable sensors.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 is a Fourier infrared spectrogram of the polyurethane material prepared in Example 1;

[0031] FIG. 2 is a diagram showing the results for transparency experiment of the polyurethane thin film prepared in Example 2, wherein “a” represents the ultraviolet transmittance of the thin film and the atomic force microscope photograph of the thin film, and “b” represents the photograph of the thin film placed on a mobile phone;

[0032] FIG. 3 is a graph showing the results for the mechanically tensile properties of the polyurethane thin film prepared in Example 3, wherein “a” represents the tensile curve of the thin film at different tensile rates, and “b” represents a photograph of the thin film with a 10 kg dumbbell suspended;

[0033] FIG. 4 is a diagram showing the adhesion states of various representative liquids on the polyurethane thin film prepared in Example 1;

[0034] FIG. 5 is a diagram showing the adhesion states of various representative liquids on the polyurethane thin film prepared in Example 1 with an elongation rate of 1800%; and

[0035] FIG. 6 is a graph showing the recovery rate of the polyurethane thin film prepared in Example 3 when stretched to 1800% and 3000% at different times.

DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below in conjunction with the examples and the appended drawings, but the embodiments of the present invention are not limited to this.

[0037] The reagents used in the examples can be conventionally purchased from the market unless otherwise specified.

[0038] The formulas of the raw materials for the anti-fouling polyurethane thin films with high elasticity and high transparency in Examples 1 to 5 are shown in Table 1 and Table 2, respectively:

TABLE-US-00002 TABLE 1 Formulas of the raw materials for the anti-fouling polyurethane materials with high elasticity and high transparency in Examples 1 to 3 Ingredients Example 1 Example 2 Example 3 Isophorone diisocyanate/g 12.00 12.00 12.00 Polytetrahydrofuran ether glycol/g 15.40 15.40 15.40 (molecular weight 1000) Trimethylol propane/g 0.70 0.70 0.70 Dimethylol butyric acid/g 1.60 1.60 1.60 3,3,4,4,5,5,6,6,7,7,8,8,8- 3.50 4.20 5.40 Tridecafluoro-1-octanol/g 1,4-butanediol/g 0.29 0.15 0.00 Dibutyltin dilaurate 0.01 0.01 0.01

TABLE-US-00003 TABLE 2 Formulas of the raw materials of the anti-fouling polyurethane materials with high elasticity and high transparency in Examples 4 to 5 Ingredients Example 4 Example 5 Isophorone diisocyanate/g 12.00 12.00 Polytetrahydrofuran ether glycol/g 15.40 15.40 (molecular weight 1000) Trimethylol propane/g 0.70 0.70 Dimethylol butyric acid/g 1.60 1.60 3,3,4,4,5,5,6,6,7,7,8,8,8- 3.50 4.20 Tridecafluoro-1-octanol/g Ethylene glycol/g 0.20 0.10 Dibutyltin dilaurate 0.01 0.01

[0039] The preparation method of the anti-fouling polyurethane thin film with high elasticity and high transparency includes the following steps:

[0040] Putting a soft segment monomer, a hydrophilic monomer and a crosslinking monomer into a four-necked flask, mixing homogeneously, adding a hard segment monomer under stirring condition, adding a catalyst dibutyltin dilaurate, and raising the temperature of the reaction system to 80° C. to react for 2 hours under such condition; then adding monohydroxy alkyl organic fluorine to continue the reaction for 2 hours. After the reaction was completed and the system was cooled to 40° C., triethylamine was added to neutralize the prepolymer. After the neutralization was completed, water was added to disperse and emulsify the prepolymer. After the prepolymer was dispersed and emulsified uniformly, an aqueous solution of a small molecular chain extender for chain extension was added for chain extension, to obtain a polyurethane aqueous dispersion with a solid content of 30%; then the polyurethane aqueous dispersion with a solid content of 30% was poured into a glass or polytetrafluoroethylene mold, for baking at a temperature of 50° C. for 24 hours, to obtain an anti-fouling thin film with low adhesion.

[0041] The Fourier infrared spectrogram of the polyurethane material prepared in Example 1 is shown in FIG. 1. It can be seen from FIG. 1 that the isocyanic acid radical in the isophorone diisocyanate raw material was exhausted, and the expected polycondensation reaction was carried out completely, wherein all the characteristic peaks corresponding to the structure of the expected product can be seen from the figure.

[0042] All the characteristic peaks corresponding to the structure of the expected product can also be seen in the Fourier infrared spectrograms of the polyurethane materials prepared in Examples 2 to 5.

[0043] The determination results for the conventional determination items of the thin films of the above-described examples, for example, thin film appearance, mechanical strength, surface-drying time and hard-drying time, and Shore hardness can all meet the technical indexes with the thin film being colorless and transparent (transparency of 95% or more), and having higher tensile stress (≥25 MPa) and moderate hardness (˜80 HA), which are not further elaborated.

[0044] Examples for Use

[0045] (1) Transparency of the Thin Film

[0046] A transmittance test and atomic force microscope observation were performed on the polyurethane thin film prepared in Example 2. The result was shown in portion a in FIG. 2, and it can be seen from portion a in FIG. 2 that the thin film had excellent transparency with UV transmittance of up to 97% at a visible light wavelength of 500 nm. The roughness of the thin film was only 4 nm, indicating that the surface of the thin film was relatively smooth. At the same time, the polyurethane thin film prepared in Example 2 was attached to a mobile phone screen, and its photograph was shown in portion b in FIG. 2. As can be seen from portion b in FIG. 2, the visibility of the screen was hardly changed, the images and text were clearly visible, and the thixotropic sensing capability of the mobile phone was also normal. Therefore, it can be seen from FIG. 2 that the polyurethane thin film prepared by the present invention had excellent transparency.

[0047] The polyurethane thin film prepared in Example 4 had an UV transmittance of 98% at a visible light wavelength of 500 nm, and the roughness of the thin film was only 3 to 4 nm; and the polyurethane thin film prepared in Example 5 had an UV transmittance of 98% at a visible light wavelength of 500 nm, and the roughness of the thin film was only 3 to 4 nm.

[0048] (2) Mechanically Tensile Properties of the Polyurethane Thin Film

[0049] The tensile curves of the polyurethane thin film prepared in Example 3 (the thin film having a thickness of 0.5 mm, a gauge length of 5 mm, and a width of 10 mm) at different stretching rates (2 to 15 mm/min) were shown in portion a in FIG. 3. It can be seen from portion a in FIG. 3 that when the stretching rate is 2 to 15 mm/min, the elongation of the thin film can reach 3100±150%. The breaking strength of the thin film can be up to 44 MPa, which may hung a 10 kg dumbbell (shown as in portion b in FIG. 3), indicating that the mechanical strength of the thin film is superior.

[0050] The mechanical properties of the polyurethane thin films prepared in Example 4 and Example 5 were examined in the same manners as that in Example 3. It can be seen that when the stretching rate was 2 to 15 mm/min, the elongation of the thin film prepared in Example 4 can reach 3000±200%, and the breaking strength of the thin film can be up to 45 MPa. When the stretching rate is 2 to 15 mm/min, the elongation rate of the thin film prepared in Example 5 can reach 3100±200%, and the breaking strength of the thin film can be up to 43 MPa.

[0051] (3) Low Adhesion and Antifouling Performance of the Polyurethane Thin Film

[0052] Five representative liquids of water, diiodomethane, hexadecane, vegetable oil, and pump oil were respectively added dropwise to the polyurethane thin films prepared in Example 1, and then these polyuretheane thin films were correspondingly inclined in angles of 50°, 12°, 13°, 18° and 19° respectively. The adhesion state of each representative liquid at different times was shown in FIG. 4. It can be seen from FIG. 4 that when the thin film is inclined at different angles, each representative liquid slides off the thin film one after another without leaving any trace, indicating that the thin film had superior low adhesion and anti-fouling properties to various liquids.

[0053] The polyurethane thin films prepared in Example 1 were stretched to 1800%, and then 5 representative liquids of water, diiodomethane, hexadecane, vegetable oil, and pump oil were correspondingly added dropwise to the stretched thin films inclined at 90°, 18°, 19°, 28°, and 31°. The adhesion state of each representative liquid on the thin film with an elongation rate of 1800% at different times was shown in FIG. 5. It can be seen from FIG. 5 that when the thin film is stretched to 1800%, each representative liquid can still slip from the inclined thin film without leaving any trace, indicating that the thin film can achieve the coexistence of both low adhesion and stretchability. The stretched thin film had superior low adhesion, with its lyophobicity having good mechanical stability.

[0054] (4) Resilience Performance of the Polyurethane Thin Film

[0055] The polyurethane thin films (10 (mm, width)*55 (mm, length)*5 (mm, thickness)) prepared in Example 3 were stretched to 3000% and 1800%, relaxed, and placed naturally at room temperature. The free recovery processes of the thin films stretched to 1800% and 3000%, the images of the thin films naturally released for 30 minutes after being stretched to 3000%, and the images of the original thin films were shown in FIG. 6. It can be seen from FIG. 6 that, the recovery rates of the thin films were both beyond 80% after 5 minutes, both beyond 90% after 30 minutes of recovery, and both reached 95% after 24 hours of recovery, which shows that the mechanical properties of the thin film were reversible.

[0056] The formula for calculating the recovery rate of the thin film was:

R.sub.r=1−ε.sub.(t)/ε.sub.max

[0057] Wherein, ε.sub.max is the elongation rate of the thin film before it is naturally released; and

[0058] ε.sub.(t) is the real-time elongation rate of the thin film after it is naturally released.

[0059] Likewise, the polyurethane thin films (10 (mm, width)*55 (mm, length)*5 (mm, thickness)) prepared in Example 4 were stretched to 3000% and 1800%, relaxed, and placed naturally at room temperature. The recovery rates of the thin films stretched to 3000% and 1800% were both beyond 80% after 5 minutes, beyond 90% after 30 minutes of recovery, and both reached 95% after 24 hours of recovery. The polyurethane thin films (10 (mm, width)*55 (mm, length)*5 (mm, thickness)) prepared in Example 5 were stretched to 3000% and 1800%, relaxed, and placed naturally at room temperature. The recovery rates of the thin films stretched to 3000% and 1800% were both beyond 80% after 5 minutes, both beyond 90% after 30 minutes of recovery, and both reached 95% after 24 hours of recovery, which shows that the mechanical properties of the thin film were reversible.

[0060] The above-mentioned examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above-mentioned examples, and any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention should all be equivalent replacement modes, and they are all included within the protection scope of the present invention.