JP2003145653A - Ultra-water-repellent, highly luminous, transparent material and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel, ultra-water-repellent, highly luminous material having the surface of a transparent material formed to have a structure that the both a brightness improving performance and high water repellency and is excellent in a mechanical strength. SOLUTION: The ultra-water-repellent, highly luminous, transparent material provided herein has a transparent water repellent layer formed on a transparent base of which the surface is formed of V-shaped grooves consecutive in one direction, of which the vertical angles of projecting and recess parts are 40 deg.-80 deg., of which angles formed by straight lines connecting the vertexes of the right and left projecting parts adjacent to the vertex of the recess part and by the horizontal direction are equally 89 deg. or below on the right and left sides and of which the cycle of the groove is 1 μm-2 mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member having super-water repellency and having the ability to enhance the brightness from the back surface.

[0002]

2. Description of the Related Art In recent years, a surface exhibiting water repellency (super water repellency) having a very high contact angle with water has been known and has been drawing attention. Superhydrophobicity has no scientific definition, and generally refers to surfaces, materials, conditions, etc. with a water contact angle of 150 ° or more. 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, electrical insulation, etc., an extremely high effect is expected compared with a water repellent surface with 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 bullet trains, ship bottom paint, outdoor lights, kitchen and kitchen utensils,
Bathrooms and toilets and their supplies, fishing nets, buoys, dental supplies,
Electrical appliances, floors and exteriors of houses, entrance doors and knobs, roofs,
Pools and poolsides, piers, gates, posts, benches, steel towers, antennas, electric wires, garages, tents, umbrellas, raincoats, sports equipment and sports clothing, helmets, leather products such as shoes and bags, cameras, videos, paper, Outdoor loudspeakers such as speakers, audio equipment, curtains, carpets,
It covers a wide range such as oiling nozzles such as gas stations, chemical plants such as refineries, metal tools, nails and screws, buckets, etc.

In order to obtain a super water-repellent state, enhancement of water repellency by imparting roughness is an essential condition. The macro wettability of a solid smooth surface to a liquid is generally described by Young's equation as follows.

[0004]

[Equation 1]

Γ _sv , γ _sl and γ _lv are surface (interface) free energy between solid-gas, solid-liquid and liquid-gas, and θ is a contact angle. Wetting on the surface to which roughness is applied makes the contribution of the surface energy of the solid large, so that the hydrophilic one becomes more hydrophilic and the water repellent one becomes more water repellent. Wenz
el [RN Wenzel, J. Phys. Colloid Chem., 53, 1466
(1949)] presented the following equation and described the wetting on a heterogeneous solid surface.

[0006]

[Equation 2]

Θ and θ ′ are contact angles on a smooth surface and a rough surface, respectively, and r is an actual surface area increased by surface roughness divided by an apparent surface area, which is called a roughness factor. Cassie [ABD Cassie, Discuss. Fa
rady Soc., 3, 11 (1948)] assumes that the interface with a liquid is a composite phase of solid and gas, and that the contribution from each phase depends on the area fraction, the contact angle between gas and water is Considering that it can be approximated to 180 °, the water repellency due to air entrapment at the solid-liquid interface was described by the following formula.

[0008]

[Equation 3]

F ₁ and θ ₁ are the area fraction of the solid at the interface with the liquid and the contact angle on the smooth solid surface, respectively. Johnso
n Jr. and Dettre [RE Johnson Jr, and RH Dettr
e. Adv.Chem.Ser., 43, 112 (1963)] performed theoretical calculation of contact angle based on roughness in an ideal system defined by amplitude and wavelength of sine curve, and smoothness When surface roughness is added to the water surface, the water repellency first rises in Wenzel mode, and when the roughness factor exceeds the roughness of about 1.8, air is trapped in the solid-liquid interface and continuously enters Cassie mode. It was shown that it would move.

On the other hand, a surface structure of a transparent material is known in which the brightness of light from the back surface is increased. For example, the commercially available Sumitomo 3M brightness enhancement film has a unique surface structure in which triangular mountain-shaped or V-groove-shaped uneven lines are connected to the surface of a transparent plastic film to collect light from the back surface. Light is emitted to improve the brightness on the front side. When this brightness enhancement film is attached to the surface of a liquid crystal display panel, for example, the brightness on the surface of the liquid crystal is increased.

[0011] For example, the use of wall materials around water such as bathrooms and washrooms and certification surface materials, lighting equipment in fountains and pools,
Two types of performance, water repellency and brightness increase, are used as the base material, surface material, design surface forming material, etc. of self-luminous materials such as automobile headlamps, street lights, neon signs, street TVs, signs, signs, and vending machines. Both of them are often required, and if they have both properties, it is possible to improve the illumination and display performance by the brightness improvement performance, and to prevent the droplets from adhering to the device or member due to the super water repellency.

In cold regions, the base material, surface material and design surface forming material for self-luminous materials such as automobile tails, headlamps, street lights, neon signs, outdoor lighting, street TVs, signs, signs and vending machines. In addition to the brightness increase performance, it is desirable to have a snow accretion prevention function.

[0013]

Therefore, an object of the present invention is to form the surface of a transparent material into a structure having both a brightness improving function and high water repellency and excellent mechanical strength in order to satisfy the above demands. Another object of the present invention is to provide a new super water repellent high brightness material.

[0014]

In order to solve the above-mentioned problems, the present invention is one in which a groove having a V-shaped surface is continuously formed in one direction, and the apex angle of the convex portion and the concave portion is 40 °. More than 8
The angle formed by the straight line connecting the apex of the concave portion and the apex of the left and right convex portions adjacent to each other at 0 ° or less and the horizontal direction is equal to 0 ° or less.
Disclosed is a superhydrophobic high-brightness transparent material, which is characterized in that a transparent water-repellent layer is formed on a transparent substrate having a groove pitch of 9 ° or less and a groove period of 1 μm or more and 2 mm or less. The superhydrophobic high-brightness transparent material has a surface shape in which the apex angle of the convex portion and the concave portion is 40 ° or more and 80 ° or less, and the straight line formed by connecting the apex of the concave portion and the apex of the adjacent left and right convex portions and the horizontal direction By forming V-shaped grooves whose angle is equal to 89 ° or less on the left and right and the groove period is 1 μm or more and 2 mm or less continuously in one direction, the roughness factor is lower and the water repellency is high. Can be maintained, the mechanical strength is improved, and the brightness of light from the back surface can be increased.

In a preferred embodiment of the present invention, the water-repellent layer is dispersed in a solvent so that the fine particles and the hydrophobic resin have a weight fraction after volatilization of 20 to 99% and 1 to 80%, respectively. It is formed by applying the produced water repellent. Higher water repellency can be imparted by forming a water repellent layer using the above water repellent.

In the present invention, the surface shape is such that V-shaped grooves are continuously formed in one direction, and the apex angle of the convex portion and the concave portion is 40 ° or more and 90 ° or less and is adjacent to the apex of the concave portion. The angle formed by the straight line connecting the vertices of the left and right convex portions and the horizontal direction is equal to the left and right and is 89 ° or less, and the groove period is 1 μm.
A water repellent agent prepared by dispersing fine particles and a hydrophobic resin in a solvent so that the weight fractions after volatilization are 20 to 99% and 1 to 80%, respectively, are applied to a substrate having a size of 2 mm or more. A super water-repellent high-brightness transparent material characterized by being formed by the above. In the above water repellent material, the apex angle of the protrusions and recesses is 40 ° or more and 90 ° or less, and the groove period is 1 μm or more and 2 m
By being m or less, the mechanical strength is further improved.

[Detailed Description of the Invention] Embodiments will be described specifically and in detail in order to facilitate understanding of the present invention. The “contact angle with water” in the present invention is a PTF having an inner diameter of 0.1 mm, using a contact angle meter (CX-150 manufactured by Kyowa Interface Science Co., Ltd.).
It is the contact angle immediately after dropping about 1 μl of water droplets from a microsyringe coated with E (polytetrafluoroethylene).

The present inventors formed columnar structures having various pitches, depths, and sizes on a silicon wafer by using a dicing saw, and because of their water repellency and tumbling property, a water repellency mode from Wenzel to Cassie. It was clarified that the variation of the value of the deviation from the calculated value of Dettre et al. Is caused by the smaller roughness (Yoshimitsuru, Akira Nakajima, Kazuhito Hashimoto, Toshiya Watabe: "Effect of roughness combination by wafer dicing on water repellency""Proceedings of the 2001 Annual Meeting of the Ceramic Society of Japan p81 (200
1)). We also clarified the same point from the behavior of water repellency due to the crater-like phase separation structure obtained by the sol-gel method. ("Processing of a Super-Hydrophobic Silica Fil
m by Combining Two Different Roughness Dimensions "
A. Nakajima, Z. Yoshimitsu, C. Saiki, K. Hashimot
o, and T. Watanabe, Ceramic Processing Science IV,
Ceramic Transactions vol. 112, p323-328 (2001), E
dited by S. Hirano, GL Messing, and N. Clausse
n, published by American Ceramic Society, Westervi
(lle, Ohio, USA) From these investigations, it is clear that the desired water repellency cannot be obtained unless the surface shape is controlled and specified together with the roughness factor when imparting roughness to obtain high water repellency. It was Then, the present inventors have made earnest studies on conditions under which superhydrophobicity is obtained with a surface shape in which V-shaped grooves as shown in FIG. 1 are continuously formed in one direction. As a result, such a structure has an apex angle of 80
It has been found that super-water repellency can be obtained by forming a smooth water-repellent layer on the surface of which the angle is less than or equal to 0, but cannot be obtained when the apex angle is equal to or more than 80. Even if the apex angle is less than 40 °, the desired water repellency can be obtained, but the tip of the convex portion becomes thin,
It is not preferable because it is inferior in physical slidability, wear resistance and impact resistance. Further, it was also found that it has a performance of increasing the brightness even within the above range of the apex angle.

The base material to which the present invention can be applied may be any of inorganic, organic, metal, and composites thereof. The roughness factor can be estimated from a laser microscope, AFM, adsorption amount measurement and the like. However, if the roughness becomes too large with respect to the water droplet, it is not preferable because the water droplet sinks into the structure due to its own weight and the self-deflection occurs, and the roughness pitch is about 1/20 or less of the size of the water droplet, that is, 1 μm. ~ 2
mm is desirable. Further, as a matter of course, in such a structure, an anisotropy occurs in the value of the contact angle, but the anisotropy becomes extremely small when approaching the super water-repellent region, and becomes negligible.

Further, in the process of forming the water repellent layer, the present inventors dispersed the fine particles and the hydrophobic resin in the solvent so that the weight fractions after volatilization were 20 to 99% and 1 to 80%, respectively. By coating the produced water-repellent agent, the roughness of the particles can be further introduced into the basic structure, the water repellency can be further emphasized by the so-called roughness mix concept, and the size of the primary particles of the particles should be 50 nm or less. Therefore, it was found that transparency can be obtained. It has been found that when the water repellent layer is formed in this manner, the effect of enhancing the water repellency by the roughness mix can be obtained, and the super water repellent state can be obtained when the apex angle of the base material is 90 ° or less. did.

If the ratio of the particles to the resin is 20% or less, it becomes difficult to introduce the roughness of the particles, and the water repellency decreases. On the other hand, when it is 99% or more, the water repellency is improved but the coatability is deteriorated. Particularly preferable composition region is 30 to 60% in weight fraction after fine particles and hydrophobic resin volatilize, respectively.
70-40%.

The fine particles in the present invention include organic fine particles and inorganic fine particles. Organic fine particles include polytetrafluoroethylene (PTFE), perfluoroalkoxy resin (PFA), ethylene tetrafluoroethylene resin (ETFE), fluorine-containing synthetic resin such as polyvinylidene fluoride (PVDF), polyethylene, polyvinyl chloride, etc. Thermoplastic resins, urea resins, phenol resins, thermosetting resins such as silicone resins, polyamide resins, acrylic resins, polycarbonates, engineering plastics such as polymer alloys, and the like. The organic fine particle powder is preferably insoluble in an organic solvent.

Examples of the inorganic fine particles include particles of one or more of oxides of silicon, tin, titanium, aluminum, zirconium, cerium, and ammotin, and carbon. Silicon oxides are preferred because of their dispersion stability, relatively uniform particle size, and easy availability of fine particles.

The inorganic fine particles of the present invention improve dispersion in a solvent, stability after dispersion, and water repellency after coating film formation.
Surface treatment can be applied. There is no particular limitation on the compound used for the surface treatment and the treatment method, but it is preferable to add fluorine or an alkyl group to the surface. Examples thereof include silylating agents, titanate coupling agents, and organometallic compounds such as alkylaluminum.

The silylating agent is a compound in which an alkyl group, an aryl group, a fluoroalkyl group containing fluorine, or the like is bonded to a hydrolyzable silyl group having affinity or reactivity with an inorganic material, and silicon Examples of the bonded hydrolyzable group include an alkoxy group, halogen, acetoxy group, silazane and the like.

As the fine particles of the present invention, a fine particle powder or a dispersion in which commercially available fine particles are dispersed can be used. Further, as a method for dispersing the fine particle powder in the solution, a high speed rotation disperser, a medium stirring type disperser (ball mill, sand mill, etc.), an ultrasonic disperser, a colloid mill disperser, a roll mill disperser, a high pressure disperser, etc. Although a known disperser can be used, an ultrasonic disperser is preferable because it can disperse uniformly and finely.

The water-repellent layer-forming material and the hydrophobic resin which can be used in the present invention may or may not contain fluorine, but they are used alone on a smooth base material surface having no roughness. When the water repellent layer is formed by using
It is more preferable that the degree is not less than °. The components of the hydrophobic resin include a resin body and a set of additives such as a curing agent and a plasticizer used when using the resin body. Examples of the present invention will be described below.

[0028]

Example 1 A film material (manufactured by Mitsubishi Rayon Co., Ltd.) in which V-shaped grooves having apex angles of convex and concave portions of 65 ° and a groove period of 50 μm are continuously formed in one direction. 2 cc of fluoroalkylsilazane (KP-801M manufactured by Shin-Etsu Chemical Co., Ltd.) is dropped on a prism sheet, and a spin coater (ASS301 manufactured by Able) is used at 1500 rpm for 1
Spin coating was performed for 0 seconds to obtain a super water repellent material. . The obtained film is transparent and has the same brightness improvement as before the water-repellent layer was formed. The contact angle of water when viewed from the direction parallel to the groove was 160 °, and the contact angle when viewed from the direction perpendicular to the groove was It was 155 °.

(Embodiment 2) The apex angle of the convex portion and the concave portion is 90 °,
A film material in which V-shaped grooves having a groove period of 50 μm are continuously formed in one direction (Sumitomo 3M B
EFII 90/50) with a hydrophobic resin (Fluoronal FL6002 manufactured by Mitsubishi Rayon Co., Ltd.) and fine particles (water repellent colloidal silica RX200 manufactured by Nippon Aerosil Co., Ltd.) at 50:50.
2 cc of a water repellent having a total solid content concentration of 1 wt% was added dropwise to the spin coater (Able Company A
Spin coating was performed at 1500 rpm for 10 seconds with SS301) to obtain a super water repellent material. The obtained film is transparent and has the same brightness improvement as before the water-repellent layer was formed. The contact angle of water when viewed from the direction parallel to the groove was 161 °, and the contact angle when viewed from the direction perpendicular to the groove was It was 156 °. The state of water drops is shown in FIG.

(Comparative Example) A film material in which V-shaped grooves having a vertical angle of 90 ° of convex portions and concave portions and a groove period of 50 μm are continuously formed in one direction (BE manufactured by Sumitomo 3M Limited)
FII 90/50) was coated in the same manner as in Example 1 to obtain a water repellent material. The obtained film is transparent and the brightness improvement is
Although the same as before the provision of the water repellent layer, the contact angle of water seen from the direction parallel to the groove was 137 ° and the contact angle seen from the direction perpendicular to the groove was 121 °.

[0031]

As described above, according to the super-water-repellent high-brightness transparent material of the present invention, a novel transparent material having a surface structure having both a high brightness improving function and excellent water repellency, which has never been obtained, can be obtained. Can be provided. The surface shape is formed by continuously forming V-shaped grooves in one direction, and the apex angle of the convex portion and the concave portion is 40 ° or more and 80 ° or less, and the apex of the concave portion and the apexes of the left and right convex portions adjacent to each other are formed. By forming a transparent base material in which the angle formed by the straight line formed by tying and the horizontal direction is equal to the left and right and is 89 ° or less, and the groove period is 1 μm or more and 2 mm or less, it is possible to obtain high water repellency while having a lower roughness factor. It is possible to provide a transparent material that maintains the strength, is excellent in mechanical strength, and has the performance of improving brightness.

It can be suitably used for various industrial products. For example, it is used as a wall material around water such as a bathroom or a washroom or a lighting surface material, lighting equipment in a fountain, a pool, etc., an automobile headlamp, It is extremely suitable for use as a base material, surface material, design surface forming material for self-luminous materials such as street lights, neon signs, street TVs, signs, signs, vending machines, etc. In addition to being able to improve the water resistance, it is possible to prevent droplets from landing on devices and members due to excellent water repellency.

[Brief description of drawings]

Fig. 1 Example of surface structure

FIG. 2 Shape of water drop on solid surface in Example 2

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Akira Nakajima             2-8-1, Honmura, Chigasaki-shi, Kanagawa Stock             Ceremony Company Advanced Technology Incubation System             Within Muzu F-term (reference) 4F100 AH06 AK01B AK52 AL05B                       AT00A BA02 DD06A DE01B                       EH46 EH462 GB08 GB33                       GB41 GB71 GB90 JB02 JB06B                       JG04 JL06 JN01A JN01B                       YY00A                 4H020 BA02 BA03 BA11

Claims (6)

[Claims] 1. A groove having a V-shaped surface is continuously formed in one direction, and the apex angle of the convex portion and the concave portion is 40 °.
The angle formed by the straight line connecting the apex of the concave portion and the apex of the right and left adjacent convex portions adjacent to each other and the horizontal direction is equal to the right and left is equal to or less than 89 ° and the period of the groove is 1 μm or more and 2 mm or less. A super water-repellent high-brightness transparent material characterized by forming a transparent water-repellent layer on a substrate. 2. A water-repellent agent prepared by dispersing the water-repellent layer in a solvent so that the fine particles and the hydrophobic resin have a weight fraction after volatilization of 20 to 99% and 1 to 80%, respectively. The super water-repellent high-brightness transparent material according to claim 1, which is formed by coating. 3. A groove having a V-shaped surface is continuously formed in one direction, and the apex angle of the convex portion and the concave portion is 40 °.
The angle formed by the straight line connecting the apex of the concave portion and the apex of the right and left adjacent convex portions adjacent to each other and the horizontal direction is equal to or more than 89 ° on the left and right, and the groove period is 1 μm or more and 2 mm or less. It is formed by applying a water-repellent agent prepared by dispersing fine particles and a hydrophobic resin in a solvent so that the weight fractions thereof after evaporation are 20 to 99% and 1 to 80%, respectively. Characteristic super water repellent high brightness transparent material. 4. The surface shape is such that the convex portions and the concave portions have apex angles of 40.
The angle between the apex of the concave portion and the apex of the adjacent left and right convex portions and the horizontal direction is equal to or more than 89 °, and the groove period is 1 μm or more and 2 mm or more.
A method for producing a super-water-repellent high-brightness transparent material, which comprises forming the following V-shaped groove continuously in one direction and forming a water-repellent layer on the surface. 5. A water-repellent agent, which is obtained by dispersing the water-repellent layer in a solvent so that the fine particles and the hydrophobic resin have a weight fraction after volatilization of 20 to 99% and 1 to 80%, respectively. The method for producing a super-water-repellent high-brightness transparent material according to claim 4, wherein the super-water-repellent high-brightness transparent material is formed. 6. The surface shape is such that the apex angle of the convex portion and the concave portion is 6
V-shaped grooves having a groove pitch of 0 ° or more and 90 ° or less and a groove period of 1 μm or more and 2 mm or less are continuously formed in one direction, and fine particles and hydrophobic resin each have a weight fraction of 20 to 20 after volatilization. 9
A method for producing a super-water-repellent high-brightness transparent material, which comprises forming a water-repellent layer by applying a water-repellent agent prepared by dispersing in a solvent so as to be 9% or 1 to 80%.