Surface treatment method, surface treatment kit, and surface-treated product

Abstract

An object of the present invention is to provide a novel surface treatment method capable of imparting water repellency and oil repellency to a surface of a treatment target, a surface treatment kit, and a surface-treated product.SOLUTION: A coating film having water repellency and oil repellency is formed on the surface of an object to be treated by performing a first step of applying a liquid agent for substrate treatment containing colloidal silica on the surface of the object to be treated and a second step of applying a liquid agent for fluorine coating containing a silane coupling agent having an organic fluorine-based compound group on the surface of the object to be treated after performing the first step.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a surface treatment method for forming a water- and oil-repellent coating on the surface of an object to be treated, a surface treatment kit, and a surface-treated object. [Background technology]

[0002] A common method for imparting water repellency and oil repellency to the surface of a workpiece is to use a fluorine coating treatment using a silane coupling agent having an organic fluorine-based compound group, such as perfluoroalkylsilane or perfluoropolyethersilane. If the workpiece is an inorganic material such as glass or metal, this type of silane coupling agent will bond to the surface through a silane coupling reaction after being applied to the surface, forming a stable layer of monomolecular fluorine-based compounds.

[0003] On the other hand, this type of silane coupling agent has the property that it is difficult to form a stable layer of a fluorine-based compound when the object to be treated is a plastic material or a painted surface.

[0004] In addition, commercially available smartphones are generally sold with a pre-treated fluorine coating on the screen, but the performance of the fluorine coating varies by manufacturer and there are individual differences between products. Therefore, users who want a fluorine coating that provides more stable performance often have their smartphones re-treated with a fluorine coating after purchasing them. Even in this case, it is difficult to stably form a layer of fluorine-based compounds on top of the original fluorine coating that exists on the screen.

[0005] In this regard, Patent Documents 1 and 2 listed below disclose a means for forming a stable fluorine-based compound layer even on a plastic surface, a painted surface, or a glass surface already coated with fluorine, by pre-coating the surface of a workpiece with polysilazane and then top-coating it with a silane coupling agent. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-59302 [Patent Document 2] JP 2023-10122 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, because polysilazane cures by reacting with hydroxyl groups, it cannot be diluted with relatively safe solvents such as water or alcohol. Therefore, polysilazane must be diluted with an organic solvent. Therefore, appropriate equipment such as exhaust systems must be installed to prevent the vaporized organic solvent from catching fire or being inhaled by workers during operation.

[0008] The present invention was completed in consideration of technical challenges, and aims to provide a novel surface treatment method, a surface treatment kit, and a surface-treated object that can impart water repellency and oil repellency to the surface of a treated object. [Means for solving the problem]

[0009] The surface treatment method of the present invention for solving the above technical problems is a surface treatment method for forming a coating having water-repellent and oil-repellent properties on the surface of a workpiece, and is characterized by carrying out a first step of applying a surface treatment liquid agent containing colloidal silica to the surface of the workpiece, and a second step of applying a fluorine coating liquid agent containing a silane coupling agent having an organic fluorine-based compound group to the surface of the workpiece after the first step has been carried out (hereinafter referred to as the "treatment method of the present invention").

[0010] In the treatment method of the present invention, a preferred embodiment is to apply a surface treatment liquid in which the solid content concentration of colloidal silica has been adjusted to 0.05 to 0.3% by weight when the first step is carried out.

[0011] In the processing method of the present invention, a mixture of water and alcohol is preferably used as a diluent for adjusting the concentration of the surface treatment solvent.

[0012] In the treatment method of the present invention, a preferred embodiment is to use a diluent containing an alcohol in an amount of 10% by weight or more and less than 60% by weight.

[0013] The surface treatment kit of the present invention, which solves the above-mentioned technical problems, is a surface treatment kit for forming a coating having water-repellent and oil-repellent properties on the surface of a workpiece, and is characterized by comprising a surface treatment liquid containing colloidal silica and a fluorine coating liquid containing a silane coupling agent having an organic fluorine-based compound group (hereinafter referred to as the "treatment kit of the present invention").

[0014] In a preferred embodiment of the treatment kit of the present invention, the colloidal silica contained in the surface treatment liquid has an average primary particle size of 10 nm or less.

[0015] In the treatment kit of the present invention, the colloidal silica contained in the surface treatment liquid is preferably an ammonia-stable type.

[0016] In the treatment kit of the present invention, the silane coupling agent having an organic fluorine-based compound group is preferably a perfluoropolyether silane.

[0017] The surface-treated article of the present invention, which solves the above-mentioned technical problems, is an article to be treated having a coating having water and oil repellency formed on its surface, characterized in that it comprises a layer of silica coating resulting from colloidal silica formed on the surface of the article to be treated, and a layer of an organic fluorine-based compound silane-coupled to the silica coating (hereinafter referred to as the "treated article of the present invention"). [Effects of the Invention]

[0018] According to the present invention, it is possible to impart water repellency and oil repellency to the surface of an object to be treated. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a perspective view showing a processed object of the present invention according to an embodiment, and a cross-sectional view showing a schematic surface state. [Figure 2] 2(a) to 2(c) are perspective views showing the execution of the treatment method of the present invention and cross-sectional views schematically showing the surface state. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 and 2, but the present invention is not limited to this embodiment.

[0021] <Processed product of the present invention 1> As shown in FIG. 1, the treated object 1 of the present invention comprises a silica coating layer 2 resulting from colloidal silica formed on the surface of the treated object 10, and a layer 3 of an organic fluorine-based compound silane-coupled to the silica coating layer 2.

[0022] <Treatment kit of the present invention> The treatment kit of the present invention is for forming a coating having water-repellent and oil-repellent properties on the surface of the workpiece 10, and comprises a "surface treatment liquid (11)" and a "fluorine coating liquid (12)".

[0023] - Surface treatment liquid 11 - The surface treatment liquid 11 contains colloidal silica. In the present invention, colloidal silica refers to fine particles of silica (silicon dioxide: SiO2) dispersed in a solvent such as water or alcohol. In this embodiment, the surface treatment liquid 11 was obtained by dissolving commercially available colloidal silica (Snowtex, product name: ST-NXS, manufactured by Nissan Chemical Industries, Ltd., solid content: 15% by weight) in a solvent (a 1:1 mixture of water and denatured alcohol (15% ethanol, 85% propanol)) so that the solid content was 0.15% by weight.

[0024] -Fluorine coating liquid 12- The fluorine coating solution 12 contains a silane coupling agent having an organic fluorine-based compound group. In the present invention, the silane coupling agent having an organic fluorine-based compound group refers to a compound having a structure in which a silyl group (including a silyl group derivative) is bonded to the end of an organic fluorine-based compound group such as a perfluoroalkyl group or a perfluoropolyether group. In this embodiment, a commercially available perfluoropolyether silane (manufactured by Unichem Co., Ltd., product name: UEC-001M) was used and dissolved in a solvent (hydrofluoroether) to give a blending amount of 1.0 wt % (net amount of perfluoropolyether silane), thereby obtaining the fluorine coating solution 12.

[0025] <Processing method of the present invention> Hereinafter, the treatment kit of the present invention is used to carry out the treatment method of the present invention for forming a water- and oil-repellent coating on the surface of the workpiece 10. The treatment method of the present invention includes a "first step" and a "second step."

[0026] -First step- In the first step, a surface treatment liquid 11 is applied to the surface of the workpiece 10. As shown in FIG. 2(a), in this embodiment, a smartphone (screen size: 6.1 inches) with a fluorine coating 4 already applied to the screen was used as the workpiece 10. As shown in FIG. 2(b), the first step was performed by dropping 0.5 ml of the surface treatment liquid 11 onto the surface (screen) of the workpiece 10, and then spreading and wiping it with a nonwoven fabric (W). By performing the first step, a silica coating layer 2 derived from colloidal silica is formed on the surface of the workpiece 10.

[0027] -Second process- In the second step, a fluorine coating solution 12 is applied to the surface of the workpiece 10 (which has been subjected to the first step). As shown in FIG. 2(c), in this embodiment, the net amount of perfluoropolyether silane applied to the surface (face) of the workpiece 10 is 0.35 g / m. 2After the fluorine coating liquid 12 was applied to the surface of the object 10 to be treated so as to form the above-mentioned surface, the second step was carried out by wiping the surface up while spreading it with a nonwoven fabric (W).

[0028] It was confirmed that the second step resulted in the stable formation of an organic fluorine-based compound layer 3 on the surface of the workpiece 10. This is presumably because the silyl group of the silane coupling agent having an organic fluorine-based compound group bonds to the silica coating formed on the surface of the workpiece by the silane coupling reaction. That is, in the treatment method of the present invention, a silica coating layer 2 is formed (precoated) on the surface of the workpiece 10 by performing the first step, and therefore the organic fluorine-based compound layer 3 can be stably formed by performing the subsequent second step. As a result, the treatment method of the present invention can be performed regardless of the material of the workpiece 10.

[0029] Furthermore, the surface of the treated object 1 of the present invention, which has been surface-treated by the treatment method of the present invention, is provided with water repellency and oil repellency by the organic fluorine compound layer 3. As a result, the surface of the treated object 1 of the present invention, which has been surface-treated by the treatment method of the present invention, develops good antifouling properties. Furthermore, the processing method of the present invention can be carried out in a relatively safe working environment because relatively safe solvents such as water or alcohol can be used as diluents to prepare the surface treatment solvent used in the first step.

[0030] [Examples 1 to 9] A surface treatment liquid was obtained in the same manner as in the above embodiment (Example 1 in the examples below), except that the colloidal silica used to prepare the surface treatment liquid was changed to one having the product name shown in Table 1 below.

[0031] [Table 1]

[0032] The treatment method of the present invention was carried out using the surface treatment liquids according to each example in the same steps as in the embodiment, and it was confirmed that a layer of an organic fluorine-based compound having good water repellency and oil repellency was stably formed in all cases.

[0033] Furthermore, it was confirmed that the smaller the colloidal silica particle size, the more stable the formation of the organic fluorine-based compound layer. This is probably because the smaller the colloidal silica particle size, the denser the silica film formed. This tendency was particularly pronounced when the surface of the treated object was already coated with fluorine, as in the embodiment. This is presumably because, during the first step of the treatment method of the present invention, the colloidal silica particles become embedded in the gaps between the organic fluorine-based compounds that grow densely on the smartphone screen, forming a denser silica coating. Therefore, in the present invention, it is preferable to use colloidal silica with an average primary particle size of 10 nm or less.

[0034] Furthermore, it was confirmed that when ammonia-stable colloidal silica was used, the layer of the organic fluorine compound was formed more stably. This is probably because, when the first step of the treatment method of the present invention is carried out, the ammonia content of the ammonia-stable colloidal silica volatilizes, forming a silica coating with higher purity.

[0035] For this reason, in the present invention, it is preferable to use ammonia-stable colloidal silica.

[0036] [Examples 10 to 12] A surface treatment liquid was obtained in the same manner as in the embodiment (ie, Example 1), except that the concentration of colloidal silica contained in the surface treatment liquid was as shown in Table 2 below.

[0037] [Table 2]

[0038] The treatment method of the present invention was carried out using the surface treatment liquids according to each example in the same steps as in the embodiment, and it was confirmed that a layer of an organic fluorine-based compound having good water repellency and oil repellency was stably formed in all cases.

[0039] It was also confirmed that the higher the concentration of colloidal silica contained in the surface treatment solution, the more stable the formation of the organic fluorine compound layer. This is probably because the higher the concentration of colloidal silica, the thicker the silica film that is formed.

[0040] However, it has also been confirmed that if the concentration of colloidal silica contained in the surface treatment liquid becomes extremely high, the silica coating formed may become uneven and discoloration may occur on the surface of the treated object.

[0041] Therefore, in the present invention, a preferred embodiment is to apply a surface treatment liquid in which the solid content concentration of colloidal silica is adjusted to 0.05 to 0.3% by weight when the first step is carried out.

[0042] [Examples 13 to 15] A surface treatment liquid was obtained in the same manner as in the embodiment (i.e., Example 1), except that the diluent for preparing the surface treatment liquid was changed to one having the components shown in Table 3 below.

[0043] [Table 3]

[0044] The treatment method of the present invention was carried out using the surface treatment liquids according to each example in the same steps as in the embodiment, and it was confirmed that a layer of an organic fluorine-based compound having good water repellency and oil repellency was stably formed in all cases.

[0045] It was also confirmed that the greater the proportion of alcohol contained in the diluent, the more improved the wettability of the surface treatment liquid during the first step of the treatment method of the present invention, improving workability.

[0046] However, if the alcohol content of the diluent exceeds 60% by weight, the surface treatment liquid will be designated as a hazardous material, and therefore, in the present invention, a diluent containing an alcohol content of 10% by weight or more and less than 60% by weight is preferably used. Note that it is preferable to use a linear or branched alcohol having 1 to 3 carbon atoms as the alcohol.

[0047] In this embodiment, a perfluoropolyether silane solution is used as the fluorine coating solution, but the silane coupling agent having an organic fluorine-based compound group contained in the fluorine coating solution is not limited to perfluoropolyether silane. It has been confirmed that the same results can be obtained when the same process as in the embodiment (example) is carried out using, for example, perfluoroalkylsilane as the silane coupling agent having an organic fluorine-based compound group.

[0048] However, since the coefficient of friction of a perfluoropolyether silane coating is lower than that of a perfluoroalkyl silane coating, the surface of an object treated with perfluoropolyether silane exhibits good finger slipperiness. Therefore, when the treatment method of the present invention is applied to a smartphone or car navigation system that inputs commands by sliding a finger across the screen, such as flicking or swiping, it is preferable to use perfluoropolyether silane as a silane coupling agent having an organic fluorine-based compound group.

[0049] It has also been confirmed that if the molecular weight or concentration of the silane coupling agent contained in the fluorine coating solution increases, water repellency and oil repellency improve, but unevenness occurs and the durability of the coating film decreases. Therefore, it has been confirmed that the molecular weight of the silane coupling agent contained in the fluorine coating solution is preferably 1500 to 6000 (more preferably 3000 to 5000), and the blending amount of the silane coupling agent contained in the fluorine coating solution is preferably 0.05 to 5.0 wt% (more preferably 0.1 to 2.0 wt%).

[0050] In the second step of the present invention, a catalyst may be added to the fluorine coating solution to promote the formation of the coating film. This catalyst may be an organic acid such as trifluoroacetic acid or an inorganic acid.

[0051] The present invention can be embodied in various other forms without departing from its spirit or main features. Therefore, the above-described embodiments (examples) are merely illustrative in all respects and should not be interpreted as limiting. The scope of the present invention is defined by the claims and is not limited in any way by the text of the specification. Furthermore, all modifications and variations within the equivalent scope of the claims are within the scope of the present invention. [Industrial Applicability]

[0052] The present invention can be suitably used as a means for imparting water repellency and oil repellency to the surface of an object to be treated. [Explanation of symbols]

[0053] 1. Treated product of the present invention 2 layers of silica coating 3. Organic fluorine compound layer 10. Material to be processed 11 Surface treatment liquid 12 Fluorine coating liquid

Claims

1. A surface treatment method for forming a water-repellent and oil-repellent coating on a surface of a workpiece, comprising: a first step of applying a surface treatment liquid containing colloidal silica to the surface of an object to be treated; a second step of applying a fluorine coating liquid containing a silane coupling agent having an organic fluorine-based compound group to the surface of the object to be treated after the first step is performed; A surface treatment method characterized by carrying out the steps of:

2. The surface treatment method according to claim 1, A surface treatment method in which, in the first step, a liquid agent for surface treatment in which the solid content concentration of colloidal silica is adjusted to 0.05 to 0.3 wt % is applied.

3. The surface treatment method according to claim 2, A surface treatment method that uses a mixture of water and alcohol as a diluent to adjust the concentration of the surface treatment solvent.

4. The surface treatment method according to claim 3, A surface treatment method using a diluent containing an alcohol in an amount of 10% by weight or more and less than 60% by weight.

5. A surface treatment kit for forming a water-repellent and oil-repellent coating on the surface of a treatment object, comprising: a surface treatment liquid containing colloidal silica; a fluorine coating liquid containing a silane coupling agent having an organic fluorine-based compound group; A surface treatment kit comprising:

6. The surface treatment kit according to claim 5, A surface treatment kit, in which the average primary particle diameter of colloidal silica contained in the surface treatment liquid is 10 nm or less.

7. The surface treatment kit according to claim 5, A surface treatment kit in which the colloidal silica contained in the surface treatment liquid is ammonia-stable.

8. The surface treatment kit according to claim 5, A surface treatment kit in which the silane coupling agent having an organic fluorine-based compound group is a perfluoropolyether silane.

9. A surface-treated product having a water-repellent and oil-repellent coating formed on its surface, a silica coating layer resulting from colloidal silica formed on the surface of the workpiece; a layer of an organic fluorine-based compound silane-coupled to the silica coating; A surface-treated product characterized by comprising:

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