WO2015159825A1

WO2015159825A1 - Structure having protrusion formed on surface thereof

Info

Publication number: WO2015159825A1
Application number: PCT/JP2015/061263
Authority: WO
Inventors: 和田惠太; 箕浦潔; 森岡聡子
Original assignee: 東レ株式会社
Priority date: 2014-04-15
Filing date: 2015-04-10
Publication date: 2015-10-22
Also published as: JP6493206B2; JPWO2015159825A1; TW201600331A

Abstract

The present invention relates to a structure having protrusions formed on the surface thereof, which can be used suitably in technical fields of micro flow paths, cell culture sheets, packaging materials, stain-proof or water-proof sheets, recording materials, screens, separators, ion exchange membranes, battery separator membrane materials, displays, optical materials and the like in which liquid repellency is required for surfaces thereof.

Description

Structure having protrusions on the surface

The present invention relates to a structure that exhibits a liquid repellent effect by having a fine structure on the surface.

Conventionally, as a means for expressing the liquid repellency effect on the surface of the structure, a technique of coating a resin having a low surface energy such as a fluoropolymer has been often applied. However, there is a limit to the liquid repellency by coating alone, and the liquid repellency as expected may not be obtained. Therefore, a method has been proposed in which a fine structure is added to the surface to obtain liquid repellency higher than that of coating (Patent Documents 1 to 3).

Further, as a fine structure that exhibits a liquid repellent effect, a protrusion having anisotropy that is oriented in a direction other than the direction perpendicular to the surface of the structure has been proposed (Patent Document 4).

JP 2004-170935 A JP 2009-187025 A JP 2009-42714 A International Publication No. 2004/048064 Pamphlet

However, in the techniques described in Patent Documents 1 to 3 described above, after the liquid adheres to the structural film in a liquid repellent state, the film needs to be tilted at a certain angle in order to move and remove the adhered liquid. There is. When the tilt of the film is small or when the film is placed horizontally, the droplets often remain on the structural film, and the expected liquid repellency effect cannot be obtained. It was.

Further, the technique described in Patent Document 4 has a problem that stable liquid repellency cannot be obtained or liquid repellency is low.

In order to solve the above problems, the present invention has the following configuration.
(1) A structure having protrusions on the surface,
(I) 70% or more of the protrusions are protrusions in which a straight line drawn from the center of the root to the center of the tip is inclined with respect to a direction perpendicular to the surface of the structure,
(Ii) The number of the protrusions on the surface of the structure is 10 or more and 4 × 10 ⁵ or less in 10,000 μm ² ;
(Iii) The average diameter D of the protrusions is 100 nm or more and 10 μm or less,
(Iv) A structure in which the ratio (H / D) of the average height H to the average diameter D of the protrusions is 1 or more and 50 or less.
(2) The structure according to (1), wherein a direction of a straight line drawn from the center of the base of the protrusion to the center of the tip is indefinite.
(3) The structure according to (1), wherein a direction of a straight line drawn from the center of the base of the protrusion to the center of the tip is constant.
(4) 70% or more of the straight line drawn from the center of the protrusion to the center of the tip forms an angle of 25 ° or more and 50 ° or less with respect to a direction perpendicular to the surface of the structure (1) ) To (3).
(5) The structure according to any one of (1) to (4), wherein a height of the protrusion is indefinite.

According to the present invention, the protrusion forms an air layer between the droplet and the protrusion when the droplet adheres, so that the contact area between the droplet and the air increases, and the liquid repellency function is remarkably increased due to the surface tension of the droplet. An improved structure can be obtained.

Furthermore, since the protrusion is inclined with respect to the vertical direction of the surface of the structure, the droplet on the surface is supported in an unstable manner, and the droplet easily moves. As a result, even when the surface of the structure is slightly tilted from the horizontal or in a horizontal state, droplets can be easily moved to suppress adhesion and remaining on the surface of the structure, making it more stable and effective. A structure having high liquid repellency and antifouling effect can be obtained. In addition, depending on the type of material constituting the liquid or the protrusion, the superhydrophilic effect may be obtained depending on the characteristics such as surface free energy and viscosity.

It is a schematic sectional drawing of the film which is a structure of this invention. It is a schematic perspective view of the film which is a structure of the present invention. It is a schematic sectional drawing of the resin film which is a structure where the direction of the straight line pulled from the center of the base of the projection which is one mode of the present invention to the center of the tip is constant. It is a schematic sectional drawing of the resin film which is a structure with which the height of the processus | protrusion which is 1 aspect of this invention is indefinite. It is a section schematic diagram showing an example of an apparatus which manufactures a film which is a structure of the present invention. It is the schematic plan view which looked at the peeling means in the apparatus which manufactures the film which is the structure of this invention from the film width direction. It is a section schematic diagram showing an example of an apparatus which manufactures a film which is a structure of the present invention. It is an example of the image which binarized the surface photograph by the scanning electron microscope of the structure of this invention used for the measurement of the number of protrusions. It is an example of the image which binarized the surface photograph by the scanning electron microscope of the structure of this invention used for the measurement of the average diameter D of a processus | protrusion. 2 is a surface photograph of a film produced according to the present invention described in Example 1 by a scanning electron microscope. 2 is a cross-sectional photograph of a film produced according to the present invention described in Example 1 by a scanning electron microscope. 2 is a surface photograph of a film produced according to the present invention described in Example 2 by a scanning electron microscope. 2 is a cross-sectional photograph taken by a scanning electron microscope of a film manufactured according to the present invention described in Example 2. FIG. 4 is a surface photograph of a film produced according to the present invention described in Example 3 by a scanning electron microscope. 4 is a cross-sectional photograph taken by a scanning electron microscope of a film manufactured according to the present invention described in Example 3. FIG. 2 is a surface photograph of a film after production described in Comparative Example 1 by a scanning electron microscope. 2 is a cross-sectional photograph of the film after production described in Comparative Example 1 using a scanning electron microscope. 4 is a surface photograph of a film after production described in Comparative Example 2 by a scanning electron microscope. 4 is a cross-sectional photograph of a film after production described in Comparative Example 2 using a scanning electron microscope. It is a surface photograph by the scanning electron microscope of the film after manufacture as described in Comparative Example 3. It is a cross-sectional photograph by the scanning electron microscope of the film after manufacture as described in Comparative Example 3.

The present invention is a structure having protrusions on the surface, and more than 70% of the protrusions, the straight line drawn from the center of the root to the center of the tip is inclined with respect to the direction perpendicular to the surface of the structure The number of the protrusions on the surface of the structure is 10 or more and 4 × 10 ⁵ or less at 10000 μm ² , and the average diameter D of the protrusions is 100 nm or more and 10 μm or less. The ratio (H / D) between the average height H and the average diameter D is preferably 1 or more and 50 or less.

Embodiments of a structure having protrusions according to the present invention will be described with reference to the drawings. 1 and 2 are a schematic sectional view (FIG. 1) and a schematic perspective view (FIG. 2) of a film which is a structure of the present invention.

The protrusions 13 present on the surface 12 of the film are preferably present independently and discretely. Here, the protrusion is a portion having a convex shape with respect to the surface 12 of the film which is the structure shown in the schematic cross-sectional view of FIG. The shape of the protrusion may be any shape, but is preferably a pyramidal shape. Further, it is preferable that a straight line 16 connecting the center 15 of the base of the protrusion and the center 14 of the tip of the protrusion is inclined from a direction 17 perpendicular to the surface 12 of the film. The center 15 of the base of the protrusion is the midpoint of the width of the protrusion bottom in the cross section. “Inclined” means that the angle formed between the straight line 16 and the direction 17 perpendicular to the surface of the structure is 5 ° or more. As a specific confirmation method, the cross-sectional inclination angle to be described next is measured as an angle formed by the straight line 16 and the direction 17 perpendicular to the surface of the structure, and is judged accordingly.
(How to find the cross-sectional inclination angle)
10 projections are selected for each of four cross sections obtained by cutting the structure in four directions perpendicular to the surface of the structure (in the above case, a film) at 45 °, and (a) Obtain the average value (hereinafter also referred to as the reference angle) between the line connecting the center of the base and the center of the tip of the protrusion and (b) the direction perpendicular to the surface of the structure. Identify the cross section with the largest. An angle formed by (a) a line connecting the center of the protrusion and the center of the tip of the protrusion in the cross section and (b) a direction perpendicular to the surface of the structure is defined as a cross-sectional inclination angle.
When the surface of the structure is a curved surface, the presence or absence of inclination is determined based on the direction 17 perpendicular to the contact surface of the center 15 at the base of the protrusion. In the present invention, it is preferable that 70% or more of the protrusions in the cross section for measuring the cross section inclination angle described above are inclined, more preferably 90% or more are inclined, and 100% are inclined. Most preferably.

Since the protrusions on the surface of the structure are inclined, the droplets on the surface of the film are supported by the inclined protrusions when the droplets are attached, so that the droplets are retained on the surface of the structure. The state becomes unstable and the droplets easily move on the surface of the structure. Droplets move from places that are inherently difficult to wet to places that are easily wetted, so the formation of tilted protrusions around the droplets causes anisotropy and non-uniformity in the wetting and promotes the movement of the droplets. Effect. As a result, even if the film is tilted slightly or even when it is horizontal, the droplets on the surface of the structure move and fall off the edge, eliminating droplet adhesion and antifouling effects. Further increase is possible.

On the surface of the structure of the present invention, when the number of protrusions is 10 to 4 × 10 ⁵ in 10000 μm ² , droplets on the surface of the structure are easily supported at the apexes of the protrusions, It is preferable because the liquid repellency is improved by increasing the contact area between the droplet and air, and more preferably 1000 or more and 4 × 10 ⁵ or less. When the number of protrusions in 10000 μm ² is more than 4 × 10 ⁵ , there is not enough space between the protrusions when the droplets are attached, and the contact area with air is reduced, so the liquid repellent effect is insufficient. It may become. If the number is less than 10, the distance between the protrusions becomes large, so that the liquid droplets may enter between the protrusions, and the flat part other than the protrusions may come into contact with the liquid droplets, resulting in a decrease in liquid repellency. Further, if the number of protrusions in 10000 μm ² is 1000 or more, the interval between the protrusions is large and the liquid droplets are less likely to enter between the protrusions, so that the liquid repellency may be further improved. Here, the number of protrusions can be read from an image obtained by obtaining an observation photograph of the surface using a scanning electron microscope and binarizing the photograph. The method of binarizing a photograph is to first average the acquired surface observation photograph using an image processing filter, remove the noise, and then clarify the boundary between the projection and the film surface as a structure. Therefore, binarization processing is performed on the surface observation photograph that has been subjected to averaging processing. The binarization is binarized with an appropriate threshold value from 0 to 256 gradations to make the protrusion clear. The threshold value for binarization is preferably set between 80 and 140. If the threshold value is smaller than 80, the region of the protrusion becomes large, and if it is larger than 140, the region of the protrusion becomes small. Therefore, the boundary between the protrusion and the surface of the structure may not be determined. Specifically, binarization is first performed at 80 as a threshold value for binarization, and the area ratio of white and black is calculated. After that, change the threshold value by 1 up to 140, calculate the area ratio at each threshold, and calculate the center point of the 5 points with the smallest difference in the area ratio at both ends of the 5 consecutive points. Binarization is performed as a threshold value. (For example, when the difference in the area ratio of 101 to 105 is the smallest, the threshold value is set to 103.) Also, binarization here refers to a gray-scaled image to two gradations of white and black. This is a process of conversion. A certain threshold value is determined, and if the value of each pixel exceeds the threshold value, it is converted to white, and if it is lower, it is converted to black.

The average diameter D of the protrusions on the surface of the structure of the present invention is preferably 100 nm or more and 10 μm or less. Here, the average diameter D is obtained by obtaining a surface observation photograph using a scanning electron microscope, and the diameter of an equal area circle of protrusions in an image obtained by binarizing the photograph (hereinafter referred to as an equivalent diameter) is the maximum. The top 10 projections and the lowest 10 projections are selected and the average of their 20 equivalent diameters is taken. However, the protrusions to be measured at this time are completely independent protrusions, and those connecting two or more protrusions are excluded at the time of the surface observation photograph. Also, the lower 10 protrusions whose equivalent diameter is less than 50 nm are not treated as protrusions. The method for binarizing a photograph is binarized by the same method as described above.

The specific measuring method for equivalent diameter is described below. In the observation photograph of the surface using a scanning electron microscope, when the protrusion is observed as a circle, the diameter is the equivalent diameter, and when it is not a circle, the diameter when the projection is replaced with a circle of equal area is the equivalent diameter. If the average diameter D is smaller than 100 nm, it takes time to obtain such protrusions uniformly and in some cases, making it extremely difficult to use industrially. If it is larger than 10 μm, it becomes difficult to form an air layer between the protrusions when the droplet is attached, and the liquid repellent effect may not be obtained.

When the area of an arbitrary range on the surface of the structure of the present invention is a base area S and the total area occupied by the bottom surfaces of the protrusions in the range is the total protrusion area A, the ratio of the total protrusion area (A / S) is It is preferably 10% or more and 30% or less. When the ratio of the total protrusion area is larger than 30%, there is not enough space between the droplet and the protrusion when the droplet is attached, and the contact area with the air is reduced. There is a case. If it is smaller than 10%, the interval between the projections becomes large, so that the droplets enter between the projections, the flat portion other than the projections contacts the droplets, and the liquid repellency may be lowered.

The ratio of the total protrusion area (A / S) is obtained, for example, as follows (explained as an example of the case where the above-mentioned arbitrary range is a square having a side of 100 μm). When a square range with one side of 100 μm is set, the base area S is 10,000 μm ² , and the total protrusion area A in this square region is obtained by observing a surface observation photograph using a scanning electron microscope, The photograph is obtained from the binarized image, and the ratio (A / S) of the total protrusion area is calculated from them. The method for binarizing a photograph is performed in the same manner as described above.

If the projections are inclined and the area occupied by the projections is difficult to read from the surface observation photograph, the film surface mold may be taken with liquid silicone rubber or the like and read from the mold surface image. When the film is peeled off from the cured liquid silicone rubber, the surface of the liquid silicone rubber becomes a surface having many holes corresponding to the bottom surfaces of the protrusions. A scanning electron micrograph of this surface is obtained and the area occupied by the holes is replaced with the area occupied by the protrusions.

Further, the ratio (H / D) between the average height H and the average diameter D of the protrusions is preferably 1 or more and 50 or less. When the ratio of the average height H to the average diameter D (H / D) is smaller than 1, it becomes difficult to form an air layer between the protrusions when the water droplets adhere, and the liquid repellent effect cannot be obtained. There is a case. On the other hand, if it is larger than 50, it may take time to obtain such protrusions. Moreover, durability may fall, such as a protrusion breaking or becoming easy to deform | transform.

Here, the average height H is obtained by selecting projections having an upper maximum height of 10 and a lower minimum height of 10 from an observation photograph of a cross section using a scanning electron microscope, and averaging those 20 projection heights. It is. The height is the distance from the surface of the structure to the top of the protrusion. Here, when 10 lower minimum heights are selected, those having a height of 50 nm or more are assumed to be protrusions, and those lower than that are not treated as protrusions.

Furthermore, the average height H of the protrusions is preferably 500 nm to 100 μm. When the average height H is smaller than 500 nm, the droplets are likely to come into contact with the base and the liquid repellency may be lowered. On the other hand, when the thickness is larger than 100 μm, the distance between the protrusions often spreads in proportion to the height. In this case, the liquid spreads between the protrusions and the liquid repellency may be lowered. Moreover, durability may fall, such as a protrusion breaking or becoming easy to deform | transform.

Further, the structure of the present invention is not limited to a film and may have any shape as long as the surface can be thermoformed. From the viewpoint of productivity and cost, a film is preferable.

Further, any material can be used as long as it can form the protrusions, and a fluororesin, silicone resin, polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polyester resin such as polybutylene terephthalate, polyethylene, polystyrene, Polyolefin resins such as polypropylene, polyisobutylene, polybutene, polymethylpentene, polyamide resins, polyimide resins, polyether resins, polyesteramide resins, polyetherester resins, acrylic resins, polyurethane resins, polycarbonate resins Or a polyvinyl chloride resin or the like is preferably used. Particularly preferred are fluororesins and silicone resins having a low surface energy, and polyolefin resins such as polyethylene, polystyrene, polypropylene, polyisobutylene, polybutene, and polymethylpentene. As a material of the structure, it is preferable to include these resins as main components. In addition, a main component means the component which occupies 50 mass% or more when the whole resin which comprises a structure is 100 mass%. In addition, 50 mass% or more is preferable and, as for the main component, 80 mass% or more is more preferable.

Furthermore, various additives can be added to the material applied to the present invention at the time of polymerization or after polymerization. Examples of additives that can be added and blended include, for example, organic fine particles, inorganic fine particles, dispersants, dyes, fluorescent brighteners, antioxidants, weathering agents, antistatic agents, mold release agents, thickeners, Examples include plasticizers, pH adjusters, and salts. In particular, as a releasing agent, low surface tension carboxylic acids such as long chain carboxylic acids or long chain carboxylates and derivatives thereof, and low surface tension alcohols such as long chain alcohols and derivatives thereof, and modified silicone oils. It is preferable to add a small amount of a compound or the like during polymerization.

Further, the structure may have a laminated structure, and the above material may be used only for the surface layer on which the protrusion is formed. By setting a material having higher strength and heat resistance than the surface layer as a layer other than the surface layer, it is possible to improve the flatness during molding and suppress deformation and wrinkling of the structure.

Furthermore, the structure may be a continuous body or a single wafer. The thickness of the structure is not particularly limited.

A preferred embodiment of the present invention is an embodiment in which the direction of a straight line drawn from the center of the protrusion to the center of the tip (hereinafter sometimes abbreviated as “projection direction”) is indefinite. Here, the direction of the protrusion is indefinite means that the direction of each protrusion is random in the space on the surface of the structure, and more specifically, the direction of each protrusion is (i) the structure. It is random in at least one of the direction in which the protrusions incline in the plane parallel to the surface of (ii) and the angle incline with respect to the direction perpendicular to the surface of the structure. In addition, since it is difficult to measure the direction or angle of each protrusion in each of (i) and (ii) except for the case where the direction of each protrusion is the same with respect to (i), Confirmation that the direction of is indefinite is made as follows without separating the above (i) and (ii). That is, when the structure is cut in four directions perpendicular to the surface of the structure in 45 ° directions and the cross section is observed, the cross section of the protrusion has the largest reference angle in the cross section. If 70% or more exceeds ± 20 ° with respect to the reference angle, it is determined that the direction of the protrusion is indefinite. Here, the reference angle refers to an angle at which ten protrusions are selected from a cross-sectional observation photograph and are inclined with respect to a direction perpendicular to the surface of the structure on the cross-section observation photograph (hereinafter referred to as “cross-section inclination angle”). Is the average angle measured. In these determinations, a scanning electron microscope may be used. Since the direction of the straight line drawn from the center of the root to the center of the tip is indefinite, nonuniformity occurs in wetting around the droplet, and the movement of the droplet can be promoted. As a result, droplets on the film are eliminated even when the film is tilted slightly or when it is horizontal, and the effect of preventing droplet adhesion can be further enhanced.

Another preferred embodiment of the present invention is an embodiment in which the direction of the protrusion is constant. Here, the direction of the protrusions being constant means that the direction of each protrusion is substantially one direction in the space on the surface of the structure, and more specifically, the direction of each protrusion is (i) It means that it is the same in both the direction in which the protrusions incline in the plane parallel to the surface of the structure and the angle (ii) the angle incline with respect to the direction perpendicular to the surface of the structure. FIG. 3 is a schematic cross-sectional view of a resin film that is a structure of the present invention in which the direction of the protrusion is constant, and (i) a cross-section parallel to the direction in which the protrusion inclines in a plane parallel to the surface of the structure. . As shown in FIG. 3, it can be determined from the cross section that the angle θ at which each protrusion is inclined (ii) with respect to the direction perpendicular to the surface of the structure is substantially constant. Confirmation that the direction of such protrusions is constant is performed as follows. When the cross section is observed by cutting the surface of the film in four directions at 45 ° intervals of 45 °, 70% or more of the protrusions are the reference in the cross section where the reference angle of the protrusion in the cross section is the largest. It is defined as being inclined in a range of ± 20 ° with respect to the angle. Here, the reference angle refers to an angle at which ten protrusions are selected from a cross-sectional observation photograph and are inclined with respect to a direction perpendicular to the surface of the structure on the cross-section observation photograph (hereinafter referred to as “cross-section inclination angle”). Is the average angle measured. In these determinations, a scanning electron microscope may be used. Since the direction of the straight line drawn from the center of the projection root to the center of the tip of the projection in the cross section is constant, wetting anisotropy occurs around the droplet and promotes the movement of the droplet in a specific direction be able to. As a result, when the film is slightly tilted in a specific direction, or even when the film is kept horizontal, droplets on the film are eliminated, and the effect of preventing droplet adhesion can be enhanced.

It is preferable that 70% or more of the straight line drawn from the center of the root to the center of the tip is inclined in a range of 25 ° or more and 50 ° or less with respect to a direction perpendicular to the surface of the structure. Here, the inclination in the range of 25 ° or more and 50 ° or less means that 70% or more of the protrusions in the cross section when the cross section is observed by cutting in a direction perpendicular to the surface of the film. Is inclined at an angle of 25 ° or more and 50 ° or less. If the inclination of the projection of 70% or more is smaller than 25 °, the non-uniformity of wetting around the droplet may not be sufficiently exhibited. Therefore, the droplets are difficult to move and may remain on the surface of the film. On the other hand, when the inclination of the protrusion of 70% or more is larger than 50 °, the contact area between the protrusion and the droplet is increased, and the liquid repellency may be impaired.

The height of the protrusion is preferably indefinite. Here, when the average height H of the protrusions is 100%, the number of protrusions whose height is less than 80% or 120% or more is 70 as the number of protrusions in the cross section. % Or more. FIG. 4 is a schematic cross-sectional view of a resin film that is a structure having protrusions on the surface of the present invention in which the height of the protrusions is indefinite. Since the height of the protrusion around the droplet is indefinite, wetting around the droplet becomes non-uniform, and the droplet easily moves. As a result, the remaining of droplets on the surface of the film is suppressed. When the film is slightly tilted in a specific direction, or even when the film is kept horizontal, droplets on the film are eliminated, and the effect of preventing droplet adhesion can be enhanced.

The film which is a structure having protrusions on the surface of the present invention can be manufactured by a process through an apparatus as shown in FIGS.

5 and 7 are schematic cross-sectional views of

manufacturing apparatuses

50 and 70 for manufacturing a film having protrusions on the surface of the film. FIG. 6 is a schematic cross-sectional view showing the operation of peeling the film from the mold in the manufacturing apparatus 50.

In the example shown in FIG. 5, in the unwinding unit 52, the film is pulled out from the unwinding roll 51 in advance, and then, in the press unit 54, the heated mold 53 having a projection structure formed on the surface is intermittently fed. A predetermined protrusion is formed on the surface of the film by pressing and pressurizing the resulting film, followed by cooling while maintaining the contact state.

The molding part is composed of a press unit 54 that forms predetermined protrusions, and a peeling means 55 that peels the film attached to the mold 53 under pressure from the mold 53. The peeling means 55 comprises a pair of peeling rolls 55A and a peeling auxiliary roll 55B arranged in parallel to hold the film so as to hold it in an S shape. One surface of the film sent intermittently is thermoformed by the mold 53 in the press unit 54, and after the thermoforming, the peeling means 55 is moved toward the upstream side as shown in FIG. The film attached to the mold 53 is peeled off from the mold 53 sequentially. Thereafter, the film is wound around a winding roll 56.

In FIG. 5, 57 and 58 indicate pressure plates, and 59 and 60 indicate buffer means provided to smoothly perform intermittent conveyance in the mold 53 portion of the film.

By adjusting the separation distance 55H between the peeling roll 55A and the mold and the temperature of the mold 53 at the time of peeling, the direction of the formed projection can be made indefinite or constant.

In addition, for example, when a separation distance 55H between the peeling roll 55A and the mold is secured, and the mold temperature at the time of peeling is set lower than the glass transition temperature of the resin constituting the film molding surface, the inclination direction is Protrusions that are constant are formed. At the time of peeling, the film is tensioned in a direction inclined from a direction perpendicular to the mold surface, and a projection is formed that is deformed to incline in a certain direction. In addition, since the film after peeling is fully cooled, even if it receives contact pressure with the peeling auxiliary roll 55B, an inclination state does not change easily.

Further, for example, when the separation distance 55H is made as small as possible and the mold temperature at the time of peeling is set in the vicinity of the glass transition temperature of the resin constituting the film molding surface, protrusions with indefinite inclination directions are formed. This is because in peeling, the film is peeled off by applying a tension in a direction substantially perpendicular to the mold surface. Therefore, a protrusion perpendicular to the surface of the film is once formed, and then a peeling assist roll with a constant pressure. This is because the protrusions that are not sufficiently cooled are deformed by being pressed by 55B and deflected in random directions.

In the example shown in FIG. 7, the film is pulled out from the unwinding roll 73 and supplied by the heating roll 75 onto an endless belt-shaped mold 76 having a projection structure formed on the heated surface.

The outer surface of the mold 76 is formed with discrete microscopic recesses that are discretely arranged, and is heated by the heating roll 75 immediately before coming into contact with the film. The continuously supplied film is pressed against the surface of the mold 76 where the concave structure is processed by the nip roll 77, and projections are formed on the surface of the film.

Thereafter, the film is conveyed to the outer surface position of the cooling roll 78 in a state of being in close contact with the surface of the mold 76. The film is cooled by heat conduction through the mold 76 by the cooling roll 78, peeled off from the mold 76 by the peeling roll 79, and taken up by the winding roll 81. Such a process makes it possible to thermoform a film on which protrusions are formed continuously with high productivity.

By adjusting the separation distance 79H between the peeling roll 79 and the mold and the temperature of the cooling roll 78, the direction of the formed protrusion can be made indefinite or constant.

For example, when the separation distance 79H between the peeling roll 79 and the cooling roll 78 is increased and the temperature of the mold at the time of peeling is set lower than the glass transition temperature of the resin constituting the film forming surface, the direction of the protrusion is constant. A structure is formed.

Further, for example, when the separation distance 79H is made as small as possible and the mold temperature at the time of peeling is set in the vicinity of the glass transition temperature of the resin constituting the film molding surface, a structure with an indefinite protrusion direction is formed. The This is because in peeling, the film is peeled off by applying a tension in a direction substantially perpendicular to the mold surface, so that a protrusion perpendicular to the surface of the film is once formed and then formed with the subsequent transport roll 80. This is because the protrusions that are pressed with a certain pressure at the time of contact with the surface and are not sufficiently cooled are deformed and deflected in a random direction.

The manufacturing method of each mold having a dent structure on the surface is a method of applying cutting, laser processing or electron beam processing directly on the metal surface, or applying cutting, laser processing or electron beam processing directly on the plating film formed on the metal surface. And a method of producing a concave shape by electroforming after producing these inverted protrusion shapes. Also, after applying the resist on the substrate, after forming the resist with a predetermined patterning by photolithography technique, the substrate is etched to form protrusions, and after removing the resist, a concave structure is formed by its inverted pattern by electroforming And the like.

It is also possible to produce a mold having a concave structure on the surface by etching the mold surface. The mold material may be silicon wafer, various metal materials, glass, ceramics, plastics, carbon materials, etc., as long as they have strength and workability with the required accuracy. Specifically, Si, SiC, SiN Polycrystalline Si, glass, Ni, Cr, Cu, Al, Fe, Ti, C and further one or more of these may be included. Alternatively, it may be produced by etching the surface of a mold having an amorphous structure mainly composed of these with a strongly acidic liquid such as nitric acid.

In the present invention, when the contact angle with water is further increased to improve the liquid repellency, a functional group having a low surface energy, in particular, on the surface of the projection obtained as described above, It is desirable to coat the fluorine group.

Such a coating treatment method is not particularly limited as long as the structure of the protrusion is not filled with a coating material. For example, the Langmuir Blodget method (LB method), physical vapor deposition method (PVD method) , Chemical vapor deposition (CVD), self-organization, sputtering, and a method in which a single molecule diluted with a solvent is applied.

In addition, it is also possible to form the protrusions by the above-described method after performing a liquid repellent treatment with an arbitrary thickness on the flat plate on which the protrusions are formed.

The structure of the present invention is suitable for building materials such as biodevices such as cell culture sheets and biochips, optical devices such as optical films and anisotropic films, liquid repellent sheets, and antifouling sheets, taking advantage of its surface characteristics. Can be used.

[Measuring method]
(Measurement of the number of protrusions)
The film was cut into 10 mm × 10 mm, and the surface was observed with a reflected electron image at a magnification of 5000 with a scanning electron microscope (Keyence VE-7800, Inc.). The image size at this time was 13.3 um × 13.3 um, the number of pixels was 375 × 375 pixels, and the size of one pixel was 35 nm × 35 nm. This image was averaged to remove noise. Thereafter, binarization was performed to clarify the boundary between the protrusion and the surface of the film.

The method of binarizing the photos was as follows. First, the obtained surface observation photograph was averaged using an image processing filter to remove noise. Thereafter, in order to clarify the boundary between the protrusion and the surface of the structure, a binarization process was performed on the surface observation photograph subjected to the averaging process. The binarization was binarized with an appropriate threshold value from 0 to 256 gradations, and the boundary between the protrusion and the film surface was clarified. In the surface image acquired this time, the threshold value for binarization was first set to 125, but when the binarized image was not obtained well, the threshold value was adjusted between 80 and 140. A photograph binarized after the averaging process is shown in FIG.

At the time of measuring the number of protrusions, measurement was performed while marking the protrusions using a Snipping Tool. The number of protrusions obtained by this method was converted to the number of protrusions in 10,000 μm ² .

(Measurement of average diameter D of protrusions)
The film was cut into 10 mm × 10 mm, and the surface was observed with a reflected electron image at a magnification of 10,000 with a scanning electron microscope (Keyence VE-7800, Inc.). The image size at this time was 12.1 μm × 9.1 μm. The number of pixels was 1280 pixels × 960 pixels, and the size of one pixel was 9.4 nm × 9.5 nm. This image was averaged to remove noise. Thereafter, binarization was performed to clarify the boundary between the protrusion and the surface of the film. The method of binarizing the photograph was performed in the same manner as in (measurement of the number of protrusions). A photograph binarized after the averaging process is shown in FIG.

From the observation photograph, the top 10 projections with the maximum equivalent diameter of the projections and the bottom 10 projections with the minimum were selected, and the average of the 20 equivalent diameters was taken as the average diameter D. In the observation photograph, when the protrusion was observed as a circle, the diameter was the equivalent diameter, and when it was not a circle, the diameter when the protrusion was replaced with a circle of equal area was taken as the equivalent diameter.

(Measurement of average height H of protrusions)
The film was cut in a direction perpendicular to the film surface, and the cross section was observed at a magnification of 5000 using a scanning electron microscope (Keyence VE-7800, Inc.). The image size at this time was 24.3 um × 18.2 um. The number of pixels was 1280 pixels × 960 pixels, and the size of one pixel was 19.0 nm × 19.0 nm. From the observation photograph, ten upper maximum heights and ten lower minimum height protrusions were selected, and the average of these 20 protrusion heights was defined as an average height H. The height is the distance from the film surface to the top of the protrusion.

(Measurement of cross-sectional inclination angle of protrusions)
The film was cut along four perpendicular planes of 45 ° with respect to the surface of the film, and the cross section of each was observed with a scanning electron microscope (Keyence VE-7800) at a magnification of 5000 times. . The observation target range was 24.3 um × 18.2 um, the number of pixels was 1280 pixels × 960 pixels, and the size of one pixel was 19.0 nm × 19.0 nm. Select 10 protrusions for each of the four observation photographs, (a) a line connecting the center of the protrusion and the center of the tip of the protrusion, and (b) a direction perpendicular to the surface of the structure. And the average value was calculated as a reference angle. The cross section in which the reference angle of the protrusion in the cross section obtained in this way is inclined most greatly is the object of evaluation, and the line connecting the center of (a) the base of the ten protrusions and the center of the tip of the protrusion in the cross section. And (b) the state of the protrusion (the presence or absence of inclination, the direction of the protrusion) was determined using the individual value of the angle formed with the direction perpendicular to the surface of the structure as the cross-sectional inclination angle. In addition, the photograph of the cross section shown in each Example and a comparative example is a photograph of the cross section in which the reference | standard angle of protrusion was inclined most.

Example 1
(1) Film A film having a thickness of 100 μm containing a polymer mainly composed of polypropylene (melting point: 144 ° C.) was used.

(2) Mold On the surface of the stainless steel plate, a material mainly composed of Ni was coated with a thickness of about 100 μm. Then, the metal mold | die with which the dent structure about 300 nm to 800 nm in diameter was formed in the whole surface with the laser processing with respect to the metal mold | die surface was produced. The area where the dent was formed was 20% with respect to the surface.

(3) Molding apparatus and conditions The apparatus as shown in FIG. 5 was applied. The press unit is a mechanism that is pressurized by a hydraulic pump. Two pressurizing plates are attached inside the press unit, and are connected to a heating device and a cooling device, respectively. The mold is placed on the upper surface of the lower pressure plate. A peeling means for peeling the film attached to the mold is installed in the press unit.

The mold temperature at the time of molding was set to 150 ° C., and the pressure was 5 MPa over the entire surface. The pressurization time was 30 seconds. The mold temperature at the time of peeling was 110 ° C.
The separation distance between the peeling roll and the film was 0.1 mm. The peeled film was sent out to the downstream winding device side and wound up.

(4) Molding result FIG. 10 shows a photograph of the projection-formed surface of the molded film using a scanning electron microscope (Keyence VE-7800). In this embodiment, protrusions having an average diameter D of 300 nm, an average height H of 1.0 μm, and a ratio of the average height H to the average diameter D (H / D) of 3.3 are formed on the entire surface. It was. At this time, the number of protrusions formed at 10,000 μm ² was 21595. The direction in which the protrusions incline was indefinite. When the film was cut in a direction perpendicular to the film surface, 70% or more of the protrusions in the cross section were inclined by 5 ° or more with respect to the direction perpendicular to the film surface. FIG. 11 is a photograph of a cross section of a resin film, which is a structure having protrusions on the surface of the present invention, taken with a scanning electron microscope, and the direction of the protrusions was indefinite.

(5) Liquid repellency / droplet transfer effect 1.41 μL of water is dropped onto the surface of the liquid repellent article, and contact of water droplets is performed using a contact angle meter (Kyowa Interface Science Co., Ltd., CA-D type). The corner was measured. When a water droplet is dropped, the water droplet rolls on the surface of the film and cannot be kept in one place, so that the contact angle cannot be measured.

(Example 2)
(1) Film A film having a thickness of 100 μm containing a polymer mainly composed of polypropylene (melting point: 144 ° C.) was used.

(2) Mold On the surface of the stainless steel plate, a material mainly composed of Ni was coated with a thickness of about 100 μm. Then, the metal mold | die with which the dent structure with a diameter of 300 nm-1.0 micrometer was formed in the whole surface with respect to the metal mold | die surface by laser processing was produced. The area where the dent was formed was 21% with respect to the surface.

(3) Molding apparatus and conditions The apparatus as shown in FIG. 5 was applied. The press unit is a mechanism that is pressurized by a hydraulic pump. Two pressurizing plates are attached inside the press unit, and are connected to a heating device and a cooling device, respectively. The mold is placed on the upper surface of the lower pressure plate. Moreover, the peeling means for peeling the film stuck on the metal mold | die is installed in the press unit. The mold temperature at the time of molding was set to 150 ° C., and the pressure was 5 MPa over the entire surface. The pressurization time was 30 seconds. The mold temperature at the time of peeling was 80 ° C. The separation distance between the peeling roll and the film was 0.3 mm. The peeled film was sent out to the downstream winding device side and wound up.

(4) Molding result FIG. 12 shows a photograph taken by a scanning electron microscope (Keyence VE-780) of the projection-formed surface of the molded film. Protrusions having an average diameter D of 350 nm, an average height H of 1.2 μm, and a ratio of the average height H to the average diameter D (H / D) of 3.4 were formed on the entire surface. At this time, the number of protrusions formed at 10,000 μm ² was 14345. Further, the range of the inclination angle of the protrusions in the cross section obtained by cutting the film in the direction perpendicular to the film surface is 20 ° to more than 70% of the protrusions in the cross section perpendicular to the film surface. The range was 45 °. FIG. 13 is a photograph of a cross section of a resin film, which is a structure having protrusions on the surface of the present invention, taken with a scanning electron microscope, and the direction of the protrusions was constant.

(5) Liquid repellency / droplet transfer effect 1.41 μL of water is dropped onto the surface of the liquid repellent article, and contact of water droplets is performed using a contact angle meter (Kyowa Interface Science Co., Ltd., CA-D type). The corner was measured. When a water droplet is dropped, the water droplet rolls on the surface of the film and cannot be kept in one place, so that the contact angle cannot be measured. At this time, the direction in which the water droplets roll was prioritized and rolled in the same direction.

Example 3
(1) Film A film having a thickness of 100 μm containing a polymer mainly composed of polypropylene (melting point: 144 ° C.) was used.

(2) Mold On the surface of the stainless steel plate, a material mainly composed of Ni was coated with a thickness of about 100 μm. Then, the metal mold | die with which the dent structure with a diameter of 350 nm to 500 nm was formed in the whole surface with laser processing with respect to the metal mold | die surface was produced. The area where the dent was formed was 6% with respect to the surface.

(3) Molding apparatus and conditions The apparatus as shown in FIG. 5 was applied. The press unit is a mechanism that is pressurized by a hydraulic pump. Two pressurizing plates are attached inside the press unit, and are connected to a heating device and a cooling device, respectively. The mold is placed on the upper surface of the lower pressure plate. A peeling means for peeling the film attached to the mold is installed in the press unit. The mold temperature during molding was 150 ° C., and the pressure was 7 MPa over the entire surface. The pressurization time was 30 seconds. The mold temperature at the time of peeling was 80 ° C. The separation distance between the peeling roll and the film was 0.3 mm. The peeled film was sent out to the downstream winding device side and wound up.

(4) Molding result FIG. 14 shows a photograph of the projection-formed surface of the molded film using a scanning electron microscope (Keyence VE-7800). Protrusions having an average diameter D of 410 nm, an average height H of 700 nm, and a ratio of the average height H of the protrusions to the average diameter D (H / D) of 1.7 were formed on the entire surface. At this time, the number of protrusions formed at 10,000 μm ² was 3200. Further, the range of the inclination angle of the protrusions in the cross section obtained by cutting the film in the direction perpendicular to the film surface is 20 ° to more than 70% of the protrusions in the cross section perpendicular to the film surface. The range was 45 °. FIG. 15 is a photograph of a cross section of a resin film, which is a structure having protrusions on the surface of the present invention, taken with a scanning electron microscope, and the direction of the protrusions was constant.

(Comparative Example 1)
(1) Film A film having a thickness of 100 μm containing a polymer mainly composed of polypropylene (melting point: 144 ° C.) was used.

(2) Mold On the surface of the stainless steel plate, a material mainly composed of Ni was coated with a thickness of about 100 μm. Then, the metal mold | die with which the dent structure with a diameter of 1.0 micrometer to 4.0 micrometer was formed in the whole surface with laser processing with respect to the metal mold | die surface was produced. The area where the dent was formed was 35% with respect to the surface.

The mold temperature at the time of molding was 150 ° C., and the pressure was 5 MPa over the entire surface. The pressurization time was 30 seconds. The mold temperature at the time of peeling was 110 ° C.

The separation distance between the peeling roll and the film was 0.1 mm. The peeled film was sent out to the downstream winding device side and wound up.

(4) Molding result FIG. 16 shows a photograph of the projection-formed surface of the molded film using a scanning electron microscope (Keyence VE-7800). Protrusions having an average diameter of 3.0 μm, an average height of 2.5 μm, and a ratio of the average height H to the average diameter D (H / D) of 0.8 were formed on the entire surface. At this time, the number of protrusions formed at 10,000 μm ² was 720. Moreover, the inclination of the protrusion was not seen. FIG. 17 is a photograph of a cross section of a resin film, which is a structure having protrusions on the surface, taken with a scanning electron microscope.

(5) Liquid repellency / droplet transfer effect 1.41 μL of water is dropped onto the surface of the liquid repellent article, and contact of water droplets is performed using a contact angle meter (Kyowa Interface Science Co., Ltd., CA-D type). The corner was measured. The contact angle at this time was 105 °, and the 10 ° contact angle was higher than that of the film before molding. The contact angle before molding was 95 °. At this time, the behavior of water droplets rolling as in Example 1 or 2 was not observed.

(Comparative Example 2)
(1) Film A film having a thickness of 100 μm containing a polymer mainly composed of polypropylene (melting point: 144 ° C.) was used.

(2) Mold On the surface of the stainless steel plate, a material mainly composed of Ni was coated with a thickness of about 100 μm. Then, the metal mold | die with which the dent structure with a diameter of 400 nm-700 nm was formed in the whole surface with laser processing with respect to the metal mold | die surface was produced. The area where the dent was formed was 10.7% with respect to the surface.

(3) Molding apparatus and conditions The apparatus as shown in FIG. 5 was applied. The press unit is a mechanism that is pressurized by a hydraulic pump. Two pressurizing plates are attached inside the press unit, and are connected to a heating device and a cooling device, respectively. The mold is placed on the upper surface of the lower pressure plate. A peeling means for peeling the film attached to the mold is installed in the press unit. The mold temperature at the time of molding was set to 150 ° C., and a pressure of 10 MPa was applied over the entire surface. The pressurization time was 30 seconds. The mold temperature at the time of peeling was 80 ° C. The separation distance between the peeling roll and the film was 0.3 mm. The peeled film was sent out to the downstream winding device side and wound up.

(4) Molding result FIG. 18 shows a photograph taken by a scanning electron microscope (Keyence VE-780) of the projection-formed surface of the molded film. Protrusions having an average diameter D of 550 nm, an average height H of 500 nm, and a ratio of the average height H of the protrusions to the average diameter D (H / D) of 0.91 were formed on the entire surface. At this time, the number of protrusions formed at 10,000 μm ² was 4500, and the total area ratio of protrusions to the base area was 7.8%. Further, the range of the inclination angle of the protrusions in the cross section obtained by cutting the film in the direction perpendicular to the film surface is 20 ° to more than 70% of the protrusions in the cross section perpendicular to the film surface. The range was 45 °. FIG. 19 is a photograph of a cross section of a resin film, which is a structure having protrusions on the surface of the present invention, taken with a scanning electron microscope, and the direction of the protrusions was constant.

(5) Liquid repellency / droplet transfer effect 1.41 μL of water is dropped onto the surface of the liquid repellent article, and contact of water droplets is performed using a contact angle meter (Kyowa Interface Science Co., Ltd., CA-D type). The corner was measured. The contact angle at this time was 131 °, and the contact angle at 36 ° was higher than that of the film before molding. The contact angle before molding was 95 °. At this time, the behavior of water droplets rolling as in Example 1 or 2 was not observed.

(Comparative Example 3)
(1) Film A film having a thickness of 100 μm containing a polymer mainly composed of polypropylene (melting point: 144 ° C.) was used.

(2) Mold On the surface of the stainless steel plate, a material mainly composed of Ni was coated with a thickness of about 100 μm. Then, the metal mold | die with which the dent structure with a diameter of 300 nm to 500 nm was formed in the whole surface with the laser processing with respect to the metal mold | die surface was produced. The area where the dent was formed was 15% with respect to the surface.

The mold temperature at the time of molding was set to 150 ° C., and the pressure was 5 MPa over the entire surface. The pressurization time was 30 seconds. The mold temperature at the time of peeling was 70 ° C.
The separation distance between the peeling roll and the film was 0.1 mm. The peeled film was sent out to the downstream winding device side and wound up.

(4) Molding result FIG. 20 shows a photograph of the projection-formed surface of the molded film using a scanning electron microscope (Keyence VE-7800). Protrusions having an average diameter of 350 nm, an average height of 1.2 μm, and a ratio of the average height H to the average diameter D (H / D) of 3.3 were formed on the entire surface. At this time, the number of protrusions formed at 10,000 μm ² was 14900. Moreover, the inclination of the protrusion was not seen. FIG. 21 is a photograph of a cross section of a resin film, which is a structure having protrusions on the surface, taken with a scanning electron microscope.

(5) Liquid repellency / droplet transfer effect 1.41 μL of water is dropped onto the surface of the liquid repellent article, and contact of water droplets is performed using a contact angle meter (Kyowa Interface Science Co., Ltd., CA-D type). The corner was measured. The contact angle at this time was 158 °, and the contact angle of 63 ° was higher than that of the film before molding. The contact angle before molding was 95 °. At this time, the behavior of water droplets rolling as in Example 1 or 2 was not observed, but when the film was tilted by 10 °, the water droplets rolled in the tilted direction.

Structures having protrusions on the surface of the present invention include microchannels, cell culture sheets, packaging materials, antifouling or waterproof sheets, recording materials, screens, separators, ion exchange membranes, battery membrane materials, displays, optical materials, etc. It is suitably used for products and members that require liquid repellency on the surface.

11: Structure 12: Film surface 13: Projection 14: Center of projection tip 15: Center of projection base 16: Straight line connecting center 15 of projection base and center 14 of projection 17: Surface of film Direction perpendicular to 12: Manufacturing device 51: Unwinding roll 52: Unwinding unit 53: Mold 54: Press unit 55: Peeling means 55A: Peeling roll 55B: Peeling auxiliary roll 55H: Peeling roll 55A and mold Separation distance 56: Winding roll 57, 58: Pressure plate 59, 60: Buffer means 61: Winding unit 70: Manufacturing device 71: Protrusion forming surface 73: Unwinding roll 74: Laminating device 75: Heating roll 76: Gold Mold 77: Nip roll 78: Cooling roll 79: Peeling roll 79H: Separation distance between the peeling roll 79 and the mold 80: Conveying roll 81: Winding roll

Claims

A structure having protrusions on the surface,
(1) 70% or more of the protrusions are protrusions in which a straight line drawn from the center of the base to the center of the tip is inclined with respect to a direction perpendicular to the surface of the structure,
(2) The number of the protrusions on the surface of the structure is 10 or more and 4 × 10 5 or less in 10,000 μm 2 .
(3) The average diameter D of the protrusions is 100 nm or more and 10 μm or less,
(4) A structure in which the ratio (H / D) of the average height H to the average diameter D of the protrusions is 1 or more and 50 or less.
The structure according to claim 1, wherein a direction of a straight line drawn from the center of the base of the protrusion to the center of the tip is indefinite.
The structure according to claim 1, wherein the direction of a straight line drawn from the center of the protrusion to the center of the tip is constant.
The straight line drawn from the center of the base of the protrusion to the center of the tip forms an angle of 25 ° or more and 50 ° or less with respect to a direction perpendicular to the surface of the structure. A structure according to any one of the above.
The structure according to any one of claims 1 to 4, wherein a height of the protrusion is indefinite.