JP2003136622A - Water-repellent solid material with low surface resistance and method for manufacturing the solid material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for manufacturing a structure showing a low surface resistance and a high water repellency. SOLUTION: A conductive substance layer is formed on the surface of a basic structure having a surface roughness and further, a water-repellent layer is formed on the conductive substance layer. Especially, the conductive substance layer is of such a type that it is formed on the surface, of the basic structure, which has a surface roughness of 1.4 or more in terms of roughness factor and is continuously grooved in a V-form in a specific direction, for example, and the water-repellent layer is formed on the conductive substance layer. Thus imparting the low surface resistance and the high water repellency to the structure can be achieved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for producing a solid having both extremely low surface resistance and water repellency.

[0002]

2. Description of the Related Art In recent years, a surface having a high contact angle with water, for example, a surface exhibiting a high degree of water repellency having a contact angle of more than 130 ° has attracted attention. Above all, the contact angle is extremely high, 15
Materials, surfaces, and conditions above 0 ° are commonly referred to as super water repellent. Such a high degree of water repellency is achieved by imparting surface roughness to the low energy surface, and the contact area between the solid and water can be significantly reduced, so that the progress of various chemical reactions via water and The formation of chemical bonds can be suppressed. Therefore, for various purposes such as snow accretion prevention, stain prevention, rust prevention, and electrical insulation, a very high effect is expected as compared with a water repellent surface having a contact angle of 100 to 110 ° obtained from a conventional smooth surface. it can. The scope of application is the exterior of vehicles such as automobiles and high-speed trains (for example, the Shinkansen), ship bottom paint, outdoor lights, kitchen and kitchen appliances, bathrooms and toilets and their accessories, fishing nets, buoys, dental supplies, and electrical equipment. , Floors and exteriors of houses, entrance doors and knobs, roofs, pools and poolsides, piers, gates, posts, benches, towers, antennas, electric wires, garages, tents, umbrellas, raincoats, sports equipment and sports clothing, helmets,
Leather products such as shoes and bags, outdoor loudspeakers and audio equipment such as cameras, video, paper, speakers, curtains, carpets, lubrication nozzles such as gas stations, chemical plants such as refineries,
Wide range of metal tools, nails, screws, buckets, etc.

Many of the low surface energy substances used to obtain such a high degree of water repellency are organic compounds, and most of them contain fluorine, and thus have a very high chargeability. For this reason, when exposed to the outdoors, various stains are easily electrostatically adsorbed, which leads to a decrease in contact angle and it is difficult to maintain high water repellency for a long time. So far, the present inventors have found that by adding a small amount of titanium oxide photocatalyst to a highly water-repellent surface, it is possible to reduce the adhesion of stains during outdoor exposure and improve the durability (A. Nakajima et al., Lan
gmuir, vol.16, [17] 7044-7047, (2000)), a technique for imparting low surface resistance to a highly water-repellent surface has not been obtained so far.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a technique for producing a structure having both low surface resistance and high water repellency. To provide.

[0005]

The method for producing a water-repellent solid having low surface resistance according to the present invention comprises forming a layer of a substance having conductivity on the surface of a basic structure having surface roughness,
It is characterized in that a water repellent layer is formed thereon.

[0006] In this method, although the surface roughness of the basic structure is 1.4 or more in terms of roughness factor, a layer of a conductive substance may be formed on the surface and a water repellent layer may be formed thereon. preferable. As the surface shape of the basic structure, for example, V-shaped grooves can be formed continuously in a specific direction, and the surface roughness of this surface is 1.4 or more in terms of roughness factor. A layer of a conductive substance can be formed on the surface of the basic structure, and a water repellent layer can be formed thereon. Further, in forming the water-repellent layer by these methods, coatings prepared by dispersing fine particles and hydrophobic resin in a solvent so that the weight fractions after volatilization are 10 to 80% and 90 to 20%, respectively. It is possible to adopt a method characterized by forming by coating a material. Furthermore, as the fine particles used in the preparation of this coating material, conductive particles can be used.

The present invention also provides a conductive water-repellent solid surface formed by such a method and a water-repellent solid having a low surface resistance produced by such a method.

[Detailed Description of the Invention] Hereinafter, the present invention will be described specifically and in detail together with preferred embodiments. In order to have high water repellency, it is essential to give the surface a certain roughness and make the surface water repellent. However, most of the substances used for water repellency have high chargeability, and adsorption of dirt due to electrostatic interaction cannot be avoided. The present inventors have diligently studied a technique for imparting low surface resistance to a highly water-repellent surface. As a result, they have found that low surface resistance can be imparted by forming a water repellent layer after forming a layer of a substance having conductivity on the surface of the base material. Further, in order to exhibit water repellency, it is particularly advantageous that the basic structure has a surface roughness of 1.4 or more as a roughness factor and a V-shaped groove formed continuously in a specific direction. I found out.

As a base material (basic structure) to which the present invention is applied
What is an inorganic, organic, metal, or composite thereof?
Anything is fine. In addition, conductive materials include metal, carbon, ITO,
 SnO ₂, ZnO, RuO₂Any of these, etc., two or more of these
You may use it in combination. When seeking transparency for solids
Is ITO, SnO₂Etc. are used. The method of forming the conductive material is
Liquid coating process even in dry process such as putter
It may be a process. Roughness factor in the present invention
Is the area fraction of the surface having roughness with respect to the smooth surface.
Estimate from laser microscope, AFM, adsorption amount measurement, etc.
You can have it.

Further, the present inventors dispersed fine particles and hydrophobic resin in a solvent so that the weight fractions after volatilization were 10 to 80% and 90 to 10%, respectively, in the process of forming the water repellent layer. By coating the prepared coating material, the roughness of particles can be further introduced into the basic structure, the water repellency can be further emphasized by the concept of so-called roughness mix, and the primary particle size of the particles should be 50 nm or less. It was found that transparency can be obtained with. It was also found that when particles having conductivity were used, the surface resistance was further reduced and the amount of addition was small because a conductive substance was formed on the base.

When the ratio of the particles to the resin is 10% or less, the effect on the surface resistance is not so great and the effect of the roughness mix on the water repellency is low. On the other hand, when it is 80% or more, the surface resistance and the water repellency are improved, but the particles cannot be sufficiently bound by the resin, and the powder falls. Particularly preferable composition regions are 40 to 60% and 60 to 40% by weight fraction after the fine particles and the hydrophobic resin volatilize, respectively. With the composition around this, an increase in conductivity due to percolation of particles can be realized, and the contact angle is also suitably improved.

The electrically conductive fine particles referred to herein may be particles of the above-mentioned electrically conductive substance, or particles of the electrically insulative substance modified or coated by some method to impart electrical conductivity. The water-repellent layer forming material or the hydrophobic resin that can be used in the present invention may or may not contain fluorine, but if they are used on a smooth base material surface having no roughness. It is necessary to select one having a water contact angle of 90 ° or more when the water repellent layer is formed. Also,
The component of the hydrophobic resin in the present invention is a total amount including not only the resin but also components necessary for using the resin, such as a curing agent and a plasticizer.

[0013]

EXAMPLES Examples of the present invention will be described below. Example 1 A film material having a roughness factor of 1.4 and V-shaped grooves continuously formed on a surface in a specific direction (PET).
[Polyethylene terephthalate] film, 3M product
ITO was formed into a film having a thickness of 150 nm on a BEF ″) by a sputtering method. On this, carbon fine particles having a primary particle diameter of 20 nm and commercially available polyester (Mitsubishi Rayon Co., Ltd.) were used.
Manufactured by "DIANAL" LR-1065) in methyl ethyl ketone with a solid concentration of 10% and a carbon / polyester ratio of 40 /
The coating material mixed in 60 was spin-coated to form a film. The obtained film is transparent, the contact angle is 152 °, and the surface resistance is 1
It was less than × 10 ⁶ Ω. The structure of this surface and the appearance of water droplets are shown in FIGS. 1 and 2, respectively. As shown in FIG. 1, a conductive material film 3 is formed on the surface of a base material 1 made of a film material having a roughness factor of 1.4 and V-shaped grooves 2 continuously formed in a specific direction on the surface. ITO film is formed,
A layer having carbon fine particles as the conductive particles 4 is formed thereon. As shown in the state of the water droplets 5 on the solid surface obtained in FIG. 2, extremely excellent water repellency could be obtained.

Comparative Example 1 A similar experiment was conducted under the conditions of Example 1 using a simple PET film (having no V-shaped groove on the surface) as a substrate. The obtained film was transparent and had a surface resistance of 1 × 10 ⁶ Ω or less, but a contact angle of 120 °.

COMPARATIVE EXAMPLE 2 ITO was added to a film material (“BEF” manufactured by 3M Co.) having a roughness factor of 1.4 and V-shaped grooves continuously formed in a specific direction on the surface under the conditions of Example 1. A similar experiment was performed using the film without forming a film. The film obtained is transparent and has a contact angle of 1.
Although it was 52 °, the surface resistance was 1 × 10 ⁷ Ω.

[0016]

As described above, according to the present invention, a surface structure excellent in low surface resistance and high water repellency can be easily produced. It can be suitably used for various industrial products, and is extremely useful in applying a high water repellency technology represented by super water repellency to a wider range of applications.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a surface structure in Example 1.

FIG. 2 is a perspective view showing a state of water droplets on a solid surface in Example 1.

[Explanation of symbols]

1 base material 2 V-shaped groove 3 Conductive substance film 4 Conductive particles 5 water drops

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuo Kieda             1-11-38 Tsujido East Coast Fujisawa City Sette M             105 F-term (reference) 4D075 AE03 CA10 CA22 CA33 CA34                       CA36 CB06 DA04 DA06 DB01                       DB11 DB48 DC01 DC05 DC08                       DC11 DC18 DC24 EA10 EB16                       EB35 EB56 EC54 EC60                 4F100 AA33 AK01A AK42 AR00A                       AR00B AR00C BA03 BA10A                       BA10C CA21C CC00C DD05                       DD06 DD07A DE01C EH46C                       JB06C JG01B JK15A JK16                       YY00A

Claims (7)

[Claims] 1. A water-repellent solid having low surface resistance, characterized in that a layer of a substance having conductivity is formed on the surface of a basic structure having surface roughness, and a water-repellent layer is formed thereon. Production method. 2. The method for producing a water-repellent solid having low surface resistance according to claim 1, wherein the surface roughness of the basic structure is 1.4 or more in terms of roughness factor. 3. The method for producing a water-repellent solid with low surface resistance according to claim 1, wherein the basic structure has V-shaped grooves formed continuously in a specific direction. 4. When forming the water-repellent layer, the weight fraction of the fine particles and the hydrophobic resin after volatilization are 10 to 80% and 90 to 90%, respectively.
The water-repellent layer with low surface resistance according to any one of claims 1 to 3, wherein the water-repellent layer is formed by coating a coating material prepared by dispersing in a solvent so as to be 20%. Solid manufacturing method. 5. The method for producing a water-repellent solid having a low surface resistance according to claim 4, wherein the fine particles used for producing the coating material have conductivity. 6. A conductive water-repellent solid surface formed by the method according to claim 1. 7. A water-repellent solid having a low surface resistance, which is produced by the method according to claim 1.