JP2007010791A - Resin film forming apparatus, resin film forming method, and diffusion reflective plate obtained by same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin film forming method which enables a reduction of tact time by reducing the number of processes in forming a resin film having unevenness on the surface, and of the cost required in an apparatus for forming the resin film to achieve low-cost simplified operation, and to provide a resin film forming apparatus. <P>SOLUTION: In the resin film forming method, a resin material containing a radical polymerization type ultraviolet curing resin is applied on an ultraviolet light transmissive substrate S to form an uncured resin film R, and the resin film for an underlayer having unevenness on the surface is formed by curing the uncured resin film R by irradiating the contact surface between the substrate S and the uncured resin film R from the side of the substrate S with ultraviolet light. The resin film forming apparatus used for the method is provided to solve the problems. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a resin film forming apparatus, a resin film forming method, and a diffuse reflector obtained thereby. More specifically, the present invention relates to a method and apparatus for forming irregularities on the surface of a resin film using a radical type ultraviolet curable resin, and a diffuse reflector using a resin film having an irregular surface.

  Conventionally, as a technique for forming irregularities on the surface of a resin film formed using a photocurable resin, photocuring is performed by irradiating a photocurable resin layer formed on a substrate with ultraviolet rays or the like through a mask on which a pattern is formed. There is known a forming method by a photolithography method in which an exposed portion or an unexposed portion of the conductive resin layer is removed with a developer.

  However, conventional resin film surface unevenness forming technology using a photo-curing resin has the following problems: photo-curing resin film thickness, photosensitivity, mask aperture ratio, exposure amount, developer concentration, developer temperature or development time. Since many factors such as adjustment are involved, there is a problem that it is difficult to obtain a desired uneven shape and the cost is high.

  As a method for solving such a problem, there has been proposed a method for forming surface irregularities by forming a photocurable resin film on a substrate, exposing it through a patterned mask, and then performing a heating process instead of an etching process ( For example, see Patent Document 1).

JP 2004-37522 A

  However, in the surface unevenness forming method described in Patent Document 1, an etching process is not necessary, but a heating process is added, so the number of processes cannot be reduced. Further, since exposure of the photocurable resin film requires a patterned mask, high-precision control of the aperture ratio and exposure amount of the mask is still required, as well as a mask forming process, a mask forming apparatus, and a mask material. This is necessary and does not lead to significant cost reduction.

  In view of the above problems, the present invention reduces the tact time by reducing the number of steps when forming a resin film having irregularities on the surface, and reduces the cost required for the resin film forming apparatus. A resin film forming method and a resin film forming apparatus that can be easily performed at low cost are provided.

Thus, according to the present invention, a resin material containing a radical polymerization type ultraviolet curable resin is applied to an ultraviolet transmissive substrate to form an uncured resin film, and the substrate and the uncured resin film are formed from the substrate side. There is provided a resin film forming method in which an uncured resin film is cured by irradiating ultraviolet rays toward a contact surface to form a base resin film having irregularities on the surface.
According to another aspect of the present invention, a stage for holding an ultraviolet transmissive substrate having an uncured resin film containing a radical polymerization type ultraviolet curable resin on the surface, and the substrate and the uncured resin from the substrate side. A resin film forming apparatus provided with an ultraviolet irradiation mechanism for irradiating ultraviolet rays toward a contact surface with a film is provided.
According to still another aspect of the present invention, there is provided a resin film having an uneven surface formed on a substrate using the resin film forming method, and a metal film formed on the uneven surface of the resin film. A diffuse reflector characterized by that.

  In the resin film forming method of the present invention, the contact surface (solid-liquid contact surface) between the substrate and the uncured resin film from the substrate side to the laminate in which the uncured resin film is formed on the ultraviolet transmissive substrate. By curing the uncured resin by irradiating it with ultraviolet rays, a curable distribution can be formed in the film thickness direction of the cured resin film. In other words, during UV irradiation, the uncured resin film has the solid-liquid contact surface closest to the light source and the farthest surface, so the curability in the film thickness direction of the uncured resin is the highest in the solid-liquid contact surface, and the solid-liquid contact surface It becomes gradually lower toward the surface, and the surface is the lowest. In addition, since the curing of the radical polymerization type ultraviolet curable resin is inhibited by oxygen, the curability of the surface of the uncured resin film is extremely low as compared with the solid-liquid contact surface side. Therefore, when the uncured resin is cured, the solid-liquid contact surface hardens and shrinks most rapidly, but the surface has fluidity due to extremely low curability, so the solid-liquid contact surface side As a result, fine irregularities having a random shape are formed on the surface.

  Therefore, according to the method for forming a resin film of the present invention, it has a fine uneven surface in two steps, an uncured resin film forming step on a substrate and an uncured resin exposure step without using a mask pattern. Since a resin film can be formed, the mask formation process and the subsequent etching process (or heating process) can be reduced. By reducing the number of processes, the takt time can be greatly shortened and the resin film can be formed with high efficiency. can do. Moreover, since the mask forming apparatus and the mask material in the mask forming process, the etching apparatus and the etching material in the etching process, or the heating apparatus in the heating process are unnecessary, the cost for the apparatus for forming the resin film having the uneven surface is reduced. The resin film can be formed easily and at a low cost.

In addition, the resin film forming apparatus of the present invention includes a stage for holding a substrate having an uncured resin film formed on the surface and an ultraviolet ray from the substrate side toward the contact surface (solid-liquid contact surface) between the substrate and the uncured resin film. It is sufficient that at least an ultraviolet irradiation mechanism for irradiating is provided. Since the apparatus configuration is simple, it can be manufactured at low cost, and a resin film can be easily formed at low cost.
In addition, according to the diffusive reflector of the present invention, a diffusive reflector having excellent reflection characteristics can be formed at low cost and efficiently in a short time.

(Description of resin film formation method)
In the resin film forming method of the present invention, an uncured resin film is formed by applying a resin material containing a radical polymerization type ultraviolet curable resin to an ultraviolet transmissive substrate, and the substrate and the uncured resin film are formed from the substrate side. The uncured resin film is cured by irradiating ultraviolet rays toward the contact surface, and a base resin film having irregularities on the surface is formed.
The resin film having a concavo-convex surface on the substrate is used as, for example, a diffusion reflection plate of a liquid crystal panel by forming a metal film on the concavo-convex surface.

  In the present invention, the main components of the radical polymerization type ultraviolet curable resin are a photoinitiator, a photoinitiator assistant, and a polymerizable substance. Radiation is generated from the photoinitiator by irradiating ultraviolet rays, and this radical Reacts with the polymerizable substance to proceed the polymerization reaction. However, this radical is deactivated by reacting with oxygen in the atmosphere and the polymerization reaction is stopped. By forming an uncured resin film with a resin material containing a radical polymerization type ultraviolet curable resin having such properties, radicals react with oxygen in the atmosphere and cure on the surface of the uncured resin film when irradiated with ultraviolet light. Sex is reduced. This will be described in detail later.

In the present invention, the material of the substrate is not particularly limited as long as it has ultraviolet transparency, and for example, a transparent glass substrate or a transparent plastic substrate can be used.
A method for forming an uncured film by applying a resin material containing the radical polymerization type ultraviolet curable resin on such a substrate is not particularly limited. For example, a spin coating method, an inkjet method, a method using a dispenser. Examples of such a coating method and printing method. The resin material may be prepared by adding an organic solvent, a pigment, an additive or the like to a radical polymerization type ultraviolet curable resin.

  The film thickness of the uncured resin film containing the radical polymerization type ultraviolet curable resin is preferably 10 μm or more, more preferably 10 to 500 μm. Curing in the film thickness direction from the solid-liquid contact surface to the surface by setting the film thickness of the uncured resin film to 10 μm or more when irradiated with ultraviolet rays at a dose that can completely cure the uncured resin film The distribution can be increased, and irregularities having a size (depth 1 to 5 μm, opening width 1 to 5 μm) that can be clearly seen on the surface of the cured resin film can be formed. . When the film thickness of the uncured resin is smaller than 10 μm, it is difficult to form irregularities on the surface of the resin film cured by irradiation with light, and when it exceeds 500 μm, most parts other than the vicinity of the surface do not contribute to the surface shape, In other words, the majority of the portions that do not affect the curable distribution necessary for forming the uneven surface shape are unfavorable in terms of material cost.

  Further, when the uncured resin film is irradiated with ultraviolet rays, the oxygen concentration in the atmosphere on the surface side of the uncured resin film may be adjusted to 20% by volume or more. By setting the oxygen concentration on the surface side of the uncured resin film to 20% by volume or more, the curability of the surface of the uncured resin film is extremely lowered, and the curable distribution in the film thickness direction of the uncured resin film is further increased. Therefore, it is possible to easily form an uneven shape having the above size on the surface of the resin film.

  Moreover, the radical polymerization type ultraviolet curable resin may contain a polyfunctional monomer having three or more functional monomers. Since the polyfunctional monomer having three or more functional monomers is more strongly polymerized three-dimensionally, the volume shrinkage ratio at the time of curing is large. Therefore, when the uncured resin is cured, the resin surface is strongly pulled to the solid-liquid contact surface side, and as a result, the uneven shape having the above size can be easily formed on the surface of the resin film.

  When the photosensitive resin is a radical polymerization type ultraviolet curable resin, the uncured resin film may contain an ultraviolet absorbing material. Since the uncured resin film contains a UV-absorbing material, the curability of the uncured resin film surface is extremely lowered, and the curable distribution in the film thickness direction is further increased, so that the surface of the resin film is The uneven shape having the above size can be easily formed.

  Further, when the resin material is applied on the substrate, the uncured resin film may be formed on the substrate with a non-uniform film thickness. In other words, by forming a thick part and a thin part in the film thickness of the uncured resin film, the surface side is less curable than the solid-liquid contact surface side, and the thick part is more curable than the thin part. Therefore, the curable distribution in the film thickness direction of the uncured resin film can be further increased, and an uneven shape having a non-uniform shape and size can be formed on the surface of the same resin film.

(Description of resin film forming apparatus)
The resin film forming apparatus of the present invention includes a stage for holding a translucent substrate having an uncured resin film containing a radical polymerization type ultraviolet curable resin on the surface, and contact between the substrate and the uncured resin film from the substrate side. And an ultraviolet irradiation mechanism for irradiating ultraviolet rays toward the surface.

  In addition, the stage is configured to have a window part for transmitting ultraviolet light (A type) on the mounting part on which the substrate is placed, or a stage having an ultraviolet transparent plate (B type) on the mounting part. be able to. Further, the stage accommodates the substrate in a removable manner, the mounting portion on which the substrate is placed has a sealed container made of a translucent material, and oxygen concentration adjusting means for adjusting the oxygen concentration in the sealed container (C type).

In the case of the A type, one or a plurality of window portions (hollow portions) can be formed by configuring the placement portion in a frame shape or a lattice shape. In the case of a frame-type window, the entire surface of the uncured resin film on the substrate can be irradiated with ultraviolet rays. Further, in the case of the lattice type window portion, since the ultraviolet ray is shielded by the lattice portion, the lattice-like light shielding portion in the resin film on the substrate is not cured, and a plurality of uncured portions are removed on a single substrate It is possible to form a resin film having individual hardened surface irregularities.
In addition, when the stage mounting portion is a frame type, as long as the uncured resin film is positioned on the window portion, the substrate can be placed with the uncured resin film facing upwards or downwards. Irradiate ultraviolet rays from below, and irradiate ultraviolet rays from above the substrate when facing downward, and irradiate ultraviolet rays toward the entire surface of the solid-liquid contact surface of the uncured resin without being blocked or reduced by the stage. be able to.
In the case of the B type, the placing portion can be formed in a table shape with transparent glass or transparent plastic.

  In the case of the C type, the sealed container has a size and shape that can accommodate a substrate, and at least a bottom portion on which the substrate is placed is formed of a light-transmitting material such as transparent glass or transparent plastic, and the substrate is taken in and out. Therefore, an opening / closing part is provided on the side wall or the upper wall. Further, as the oxygen concentration adjusting means, an oxygen gas supply source and an inert gas supply source connected to the gas flow pipe, a gas introduction pipe capable of communicating and shutting off the gas supply source and the sealed container, a sealed container, A gas discharge pipe that can communicate with the outside can be provided, and oxygen gas and inert gas can be quantitatively introduced into the sealed container.

  As an ultraviolet irradiation mechanism, it is only necessary to irradiate ultraviolet rays having a wavelength of about 200 to 400 nm. For example, a high pressure mercury lamp, a xenon lamp, a metal halide lamp, a tungsten lamp, or the like can be used. At this time, ultraviolet light having an arbitrary wavelength may be extracted using an optical filter that removes ultraviolet light in a specific wavelength range. Further, the ultraviolet light irradiation mechanism may be an integral type or a separate type of light source body and irradiation unit. In the case of a separate type, the light source body and the irradiation unit can be connected by an optical fiber cable.

(Explanation of diffuse reflector)
The diffusive reflecting plate in the present invention is formed by using a translucent substrate having a resin film having a concavo-convex surface produced by the above method, and forming a metal film on the concavo-convex surface of the resin film. As the metal film, a metal film having a high light reflectance such as silver or aluminum is used, and low-cost aluminum is preferable. The method for forming the metal film on the uneven surface of the resin film is not particularly limited, and examples thereof include a vapor deposition method and a plating method. Among them, the vapor deposition method is a viewpoint that an excellent film quality and a uniform film thickness can be easily obtained. To preferred.
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

(Embodiment 1)
FIG. 1 is a schematic perspective view for explaining a resin film forming method and apparatus according to Embodiment 1 of the present invention, FIG. 2 is a schematic side view of a stage of the resin film forming apparatus in FIG. 1, and FIG. It is a top view of the stage of this resin film forming apparatus.
The resin film forming apparatus according to the first embodiment includes a stage 10 for holding a translucent substrate S on which an uncured resin film R formed by applying a resin material containing a radical polymerization type ultraviolet curable resin is formed on one surface. And an ultraviolet irradiation mechanism 15 that can irradiate ultraviolet rays from below or above the substrate S placed on the stage 10.

The stage 10 includes a rectangular frame 11 on which the substrate S is placed, and a height adjusting unit 12 that supports the frame 11 and adjusts the height from the installation surface of the frame 11.
The frame body 11 has a hollow window portion 11a for transmitting ultraviolet rays inside, and a plurality of frame bodies 11 for positioning the substrate S at predetermined positions by contacting two adjacent sides of the substrate S placed thereon ( In the first embodiment, three positioning pins 11b are provided. In a state where the substrate S is placed and positioned on the frame body 11, the entire region of the uncured resin film R is arranged at the position of the cavity window portion 11a. A configuration in which a plate made of a translucent material such as a transparent glass plate or a plastic plate is fitted in the hollow window portion 11 a, or a plate made of a translucent material may be used instead of the frame body 11.
The height adjusting means 12 includes four leg portions 12a provided at the four corners of the lower surface of the frame 11, and a lifting mechanism (not shown) that lifts and lowers each leg portion 12a independently or in conjunction with each other. The lifting mechanism is not particularly limited, and for example, the legs can be lifted and lowered using a cylinder, a rack and pinion mechanism, or the like.

  The ultraviolet irradiation mechanism 15 includes a light source body 15a, an optical fiber cable 15b, and a direct irradiation unit 15c for uniformly irradiating ultraviolet rays in a plane, and the light source body 15a has a built-in timer capable of setting the ultraviolet irradiation time. ing. Since the stage 10 and the ultraviolet irradiation mechanism 15 are independent from each other, the number of the ultraviolet irradiation mechanisms 15 may be changed as necessary.

Next, a resin film forming method using the resin film forming apparatus of Embodiment 1 will be described with reference to FIGS.
First, a resin material containing a radical polymerization type ultraviolet curable resin was applied onto the substrate S by spin coating to form an uncured resin film R. At this time, five samples in which the film thickness of the uncured resin film was 1 μm, 5 μm, 7 μm, 10 μm, and 15 μm were prepared by adjusting the rotation speed of the spin coat. As the ultraviolet transmissive substrate S, an alkali-free glass substrate (52 mm × 52 mm × 0.7 mm) was used. Further, as a radical polymerization type ultraviolet curable resin, an ultraviolet curable resin SD2407 manufactured by Dainippon Ink Co., Ltd. is used, and the ultraviolet curable resin and butyl carbitol acetate as an organic solvent are diluted to a volume ratio of 1: 1 to obtain a resin. The material was prepared.

  Next, the substrate S was placed on the frame 11 of the stage 10 with the uncured resin film R facing upward, and the entire region of the uncured resin film R was placed in the hollow window 11a of the stage 10 by the positioning pins 11b. At this time, the time from the formation of the uncured resin film R to the placement of the substrate S on the stage 10 was about 10 seconds. In addition, the direct irradiation unit 15c of the ultraviolet irradiation mechanism 15 is previously disposed below the frame body 11, and the direct adjustment unit is moved from the solid-liquid contact surface, which is the contact surface between the uncured resin film R and the substrate S, by the height adjusting unit 12. The height of the frame 11 was adjusted so that the distance to 15c was 2.5 cm. The ultraviolet irradiation mechanism 15 uses an ultraviolet irradiation device EX250 (ultraviolet irradiation lamp) manufactured by HOYA CANDEO OPTRONICS as the light source body 15a, and uses an HDI-SQ manufactured by HOYA CANDEO OPTRONICS as the direct irradiation unit 15c. Connected and configured.

  After placing the substrate S on the stage 10, the ultraviolet ray irradiation mechanism 15 immediately irradiated with ultraviolet rays for 30 seconds to cure the uncured resin film R to form a resin film having an uneven surface. At this time, when the ultraviolet light is irradiated from the substrate S side toward the solid-liquid contact surface between the substrate S and the uncured resin film R, as shown in FIG. 4, the curability of the solid-liquid contact surface R1 closest to the direct irradiation unit 15c. Is the highest, and the curability of the surface R2 farthest from the direct unit 15c is the lowest. Furthermore, the radical polymerization type UV curable resin contained in the uncured resin film R is such that the radical necessary for the progress of the curing reaction reacts with oxygen in the atmosphere to inhibit the progress of the curing reaction, and the surface R2 is cured. Sex is further reduced. In this way, in the uncured resin film R, by forming a curable distribution having extremely low curability on the surface R2 in the film thickness direction, when the curing reaction of the solid-liquid contact surface R1 proceeds and contracts, The surface R2 which is uncured and has fluidity is pulled, and as a result, an uneven shape can be formed on the surface of the cured resin film.

  FIG. 5 is a schematic cross-sectional side view explaining the depth of unevenness on the surface of the resin film formed on the substrate. FIG. 6 shows the thickness of the uncured resin film and the depth of surface unevenness obtained by the above method. FIG. 7 shows the depth and width of the surface irregularities of a resin film obtained from an uncured resin film having a film thickness of 15 μm. In FIG. 5, the difference between the portion indicated by the arrow, that is, the deepest portion and the highest portion of the surface unevenness of the resin film is defined as the surface unevenness depth in the present invention.

As shown in FIG. 6, in the case of sample a using an uncured resin film having a thickness of 1 μm, no irregularities were found on the surface of the resin film after ultraviolet irradiation. In addition, in the case of sample b and sample c using uncured resin films having a film thickness of 5 μm and 7 μm, slight unevenness was confirmed. On the other hand, in the case of sample d using an uncured resin film having a film thickness of 10 μm, it was found that the surface shape of the resin film after ultraviolet irradiation was clearly uneven, and an uncured resin film having a film thickness of 15 μm was used. In the case of sample e, the unevenness was even larger. This is presumably because the larger the thickness of the uncured resin film, the greater the distribution of curability in the film thickness direction, and the easier it is to form the surface irregular shape R3 (see FIG. 5). In other words, it was found that when the film thickness of the uncured resin film is small, it is necessary to increase the distribution of curability by some means.
Thus, it can be seen that by changing the film thickness of the uncured resin film, it is possible to form the surface unevenness R3 of any size on the cured resin film, especially when the film thickness of the uncured resin film is 10 μm or more. It was found that a large surface irregular shape R3 could be formed. Moreover, as shown in FIG. 7, the resin film obtained from the uncured resin film having a film thickness of 15 μm has a surface unevenness R3 having a random pattern shape with a depth of about 3 μm and an opening width of about 6 μm. I understood. The depth and width of the surface irregularities in FIGS. 6 and 7 were measured with a Keyence color 3D shape measurement microscope VK-9500.

  Thus, according to the present invention, it is possible to form the resin film having the concavo-convex shape R3 on the surface in a short time without performing a post-process such as development or heating. Furthermore, a photomask having a pattern formed at the time of ultraviolet irradiation is not necessary, and facilities for development and heating are not necessary, so that the cost can be reduced.

  In the first embodiment, the uncured resin film R is formed on the substrate S by spin coating. However, the same result is obtained when an uncured resin film is formed by applying a resin material with a uniform film thickness by inkjet. Met. Moreover, although the glass substrate was used as the board | substrate S in this Embodiment 1, it confirmed that it should just be a board | substrate which permeate | transmits an ultraviolet-ray. In the first embodiment, the distance from the direct irradiation unit 15c of the ultraviolet irradiation mechanism 15 to the solid-liquid contact surface R1 of the uncured resin R is 2.5 cm, but the ultraviolet irradiation intensity is changed by changing the distance. Even in cases, the results were confirmed to be similar.

(Embodiment 2)
In the first embodiment, the case of irradiating ultraviolet rays from the lower side of the substrate placed on the stage is exemplified, but it is not always necessary to have this configuration, and as shown in FIG. 8, uncured at the position of the cavity window portion 11a. The substrate S may be installed on the frame 11 with the resin film R facing downward, and ultraviolet rays may be irradiated from above to the solid-liquid contact surface of the uncured resin film R. In this case, a holding member for horizontally holding the direct irradiation unit 15c is provided, and the distance from the direct irradiation unit 15c to the solid-liquid contact surface is set to a predetermined distance by the height adjusting means 12 of the stage 10.
According to the second embodiment, similarly to the first embodiment, a resin film having an uneven surface shape can be obtained in a short time and at a low cost.

(Embodiment 3)
As shown in FIG. 9, the resin film forming apparatus of the third embodiment is the same as the first embodiment in the ultraviolet irradiation mechanism 15, but the stage 20 is different and an oxygen concentration adjusting means 27 is further provided. In FIG. 9, the same elements as those in the first embodiment are denoted by the same reference numerals.

  The stage 20 has an airtight container 21 having an opening / closing part capable of taking in and out the substrate S on which the uncured resin film R is formed, and a height adjusting unit 12 similar to the first embodiment that supports the airtight container 21 so that the height can be adjusted. And. The sealed container 21 is a rectangular flat type made entirely of a translucent material (plastic, glass, etc.), and a plurality of positioning pins 11b similar to those in the first embodiment are provided on the inner surface of the bottom wall.

  The oxygen concentration adjusting means 27 includes an oxygen gas cylinder 27a, a nitrogen gas cylinder 27b, a gas introduction pipe 28 connecting the gas cylinders 27a and 27b and the sealed container 21, and an on-off valve 28a provided in the gas introduction pipe 28. And a gas discharge pipe 29 for discharging the gas in the sealed container 21 to the outside, and an opening / closing valve 29b provided in the gas discharge pipe 29. The opening / closing valves 28a and 29a are opened and closed, and the nitrogen in the sealed container 21 is provided. Alternatively, the amount of oxygen in the container 21 can be controlled by supplying and exhausting oxygen, and the inside of the sealed container 21 can be sealed to adjust the internal oxygen concentration to a predetermined concentration (volume%).

Next, a resin film forming method using the resin film forming apparatus of Embodiment 3 will be described with reference to FIG.
First, an uncured resin film R having a thickness of 10 μm is formed on the substrate S in the same manner as in the first embodiment except that a UV coat varnish manufactured by T & K TOKA is used as the photosensitive resin. Installed inside and sealed. Next, after adjusting the oxygen concentration in the sealed container 21 to a predetermined concentration by the oxygen adjusting means 27 and controlling the atmosphere, the ultraviolet irradiation mechanism 15 performs ultraviolet irradiation to form a resin film sample having an uneven surface. did. At this time, the distance between the direct irradiation unit 15c and the solid-liquid contact surface is 2.5 cm.
Five types of samples were prepared when the oxygen concentration was changed to 0%, about 11%, about 20%, about 26%, and about 30%.

The relationship between the depth of the surface irregularities of the resin films of these samples f to j and the oxygen concentration is shown in FIG.
In the case of samples f and g produced with oxygen concentrations of 0% by volume and 11% by volume, irregularities could not be confirmed on the surface of the resin film. On the other hand, in the case of samples h, i, and j prepared with an oxygen concentration of 20% by volume or more, it was found that the unevenness was clearly confirmed on the resin film surface, and the uneven shape was increased as the oxygen concentration was increased. That is, as the oxygen concentration around the uncured resin film R is higher, the curing of the radical polymerization type ultraviolet curable resin on the surface of the uncured resin film R is inhibited by oxygen, and the film thickness direction of the uncured resin film R This is considered to be due to the remarkable distribution of curability. From these results, it was found that the size of the surface irregularities can be controlled by controlling the oxygen concentration around the uncured resin film R. In particular, it was confirmed that unevenness can be easily formed on the surface by setting the oxygen concentration to 20% by volume or more.

  In the third embodiment, UV coat varnish manufactured by T & K TOKA was used as the radical polymerization type UV curable resin, but the same result was obtained with the UV curable resin SD2407 manufactured by Dainippon Ink Co., Ltd. used in the first embodiment. Obtained. In Embodiment 3, the stage 20 is a sealed stage and the atmosphere around the uncured resin film R is controlled. However, the entire resin film forming apparatus is sealed to control oxygen around the apparatus. May be.

(Embodiment 4)
In Embodiment 4, as a radical polymerization type ultraviolet curable resin, Arakawa Chemical's UV curable resin beam set EM-90 (functional group number 6), beam set EM-92 (functional group number 4), beam set 550B (functional group number 3). A sample in which a resin film was formed on a substrate was prepared by the same apparatus and method as in Embodiment 1 except that the beam set 510 (functional group number 2) was used. However, the beam sets EM-90 and EM-92 were not diluted, and the beam set 510 and the beam set 550B were diluted with a diluent beam set 770 manufactured by Arakawa Chemical Co. at a volume ratio of 1: 1. At this time, the distance between the direct irradiation unit and the solid-liquid contact surface is 2 cm.
As samples using the above four types of resins, the thickness of the uncured resin film was 1 μm, 5 μm, 7 μm, and 10 μm, and a total of 16 types of samples were produced.

FIG. 11 shows the relationship between the depth of the surface irregularities of the resin film of the sample prepared using the above four types of resins and the film thickness of the uncured resin film. In FIG. 11, ◆ is a beam set EM-90 (functional group number 6), □ is a beam set EM-92 (functional group number 4), X is a beam set 550B (functional group number 3), and Δ is a beam set 510 (functional group). Samples using radix 2) are shown.
From the results shown in FIG. 11, the larger the number of functional groups of the ultraviolet curable resin contained in the uncured resin film, the more the three-dimensional bonds and the volume shrinkage at the time of curing increase. It was found that a shape could be formed. In particular, when the number of functional groups of the ultraviolet curable resin contained in the uncured resin film is 3 or more, the volume shrinkage rate of the uncured resin film is significantly increased, so that the curing / shrinkage that proceeds from the solid-liquid contact surface side is performed. In addition, it was found that the surface was pulled more strongly and the surface uneven shape could be easily formed.

(Embodiment 5)
In Embodiment 5, a sample in which a resin film is formed on a substrate by the same apparatus and method as in Embodiment 1 except that IJT UV ink (cyan) was used as the radical polymerization type ultraviolet curable resin was prepared. did. However, since the UV ink manufactured by IJT contains a cyan pigment having an ultraviolet absorption effect and is diluted with an organic solvent in advance, in the fifth embodiment, the UV ink is not diluted with an organic solvent. At this time, the distance between the direct irradiation unit and the solid-liquid contact surface is 2 cm.
As samples using the UV ink, the thickness of the uncured resin film was 1 μm, 5 μm, 7 μm, 10 μm, and 15 μm, and a total of five types of samples were prepared.

FIG. 12 shows the relationship between the depth of the surface irregularities of the resin films of the five types of samples k to o and the film thickness of the uncured resin film.
From the results of FIG. 12, it was found that the depth of the surface irregularities formed on the surface of the resin film becomes deeper as the film thickness of the uncured resin film is larger as in the first embodiment. Furthermore, compared with the result of Embodiment 1 (see FIG. 6), in the case of Embodiment 5 in which the uncured resin film contains a material having an ultraviolet absorption effect, the film thickness of the uncured resin film is 7 μm (sample m It was found that surface irregularities having a depth of 1 μm or more can be formed even in a small case.
The results of the fifth embodiment will be further described with reference to FIG. 13. When the uncured resin film R contains a cyan pigment which is a material having an ultraviolet absorption effect, the ultraviolet light is uncured from the solid-liquid contact surface R1 side. While passing through the inside of R, it is absorbed by the cyan pigment, thereby reducing the amount of ultraviolet irradiation to the surface R2 and lowering the curability of the surface R2. Therefore, a curable distribution is formed in the film thickness direction of the uncured resin film R.

  In this Embodiment 5, UV ink manufactured by IJT was used as the radical polymerization type UV curable resin, but used in Dainippon Ink UV curable resin SD2407 and Embodiment 2 used in Embodiment 1. Similar results were obtained when the cyan pigment was dispersed in T & K TOKA's UV coat varnish. In other words, by adding an ultraviolet absorbing material or a material having an ultraviolet absorbing effect to a radical polymerization type ultraviolet curable resin, surface irregularities can be formed even under conditions where surface irregularities cannot be formed normally or only small surface irregularities can be formed. I understood. In the fifth embodiment, an ink containing a cyan pigment is used as a material having an ultraviolet absorption effect, but other color pigments may be used as long as they absorb ultraviolet rays. Since the amount of absorption of ultraviolet rays varies depending on the color of the pigment and the like, a material having an ultraviolet absorption effect may be selected according to the required surface irregularity, the curability of the ultraviolet curable resin to be used, and the film thickness.

(Embodiment 6)
In the fifth embodiment, as shown in FIG. 14, the same apparatus and method as in the first embodiment except that the uncured resin film R is formed on the substrate S with a continuously changing film thickness using a dispenser. A sample in which a resin film was formed on a substrate was produced. The uncured resin film R has a diameter of about 300 μm and a maximum thickness of 30 μm. As samples, the film thickness of the uncured resin film was 1 μm, 7 μm, 10 μm, 15 μm, and 30 μm, and a total of five types of samples were produced.

FIG. 15 shows the relationship between the depth of the surface irregularities of the resin films of the five types of samples p to t and the film thickness of the uncured resin film.
From the result of FIG. 15, as in the first embodiment, even in the same uncured resin film, the depth of the surface unevenness of the formed resin film becomes deeper as the film thickness becomes larger, and the part where the film thickness becomes smaller It was found that the depth of the surface unevenness of the formed resin film was reduced. That is, in the uncured resin film R whose film thickness is not constant, the distance between the solid-liquid contact surface R1 and the direct irradiation unit 15c is the same at any position, but the distance between the surface R2 and the direct irradiation unit 15c is uncured. Since it is not constant in the resin film R, it indicates that the larger the film thickness, the greater the distribution of curability. Therefore, it was found that by continuously changing the film thickness within the same uncured resin film R, it is possible to form surface irregularities having different sizes corresponding to the change in the film thickness.

  In the sixth embodiment, the uncured resin film R whose film thickness continuously changes is formed by the dispenser. However, the resin material on the substrate S by other means capable of forming a non-uniform film thickness, such as a dropper or a pipette. May be dropped to form the uncured resin film R.

(Embodiment 7)
In the seventh embodiment, the cured resin film having surface irregularities having a thickness of 3.02 μm and a width of 2.31 μm formed in the first embodiment is used. When this resin film was observed by irradiating transmitted light from the uneven surface side, it was found to be an optical film exhibiting good diffusibility. A diffusion reflector was formed by depositing aluminum with a thickness of 0.1 μm on this resin film by vacuum deposition.

Reflection characteristics of this diffuse reflector, more specifically, the incident angle dependence of the reflection intensity (relative intensity with respect to the standard white plate) directly in front of the diffuse reflector using the transfer prototype obtained by UV irradiation of 1.5 J / cm ² Is shown in FIG.
As can be seen from FIG. 16, the diffusive reflector of Embodiment 7 has a high reflection intensity in the range of the incident light angle of ± 20 degrees. Since the incident light angle required for the diffuse reflection plate of the reflective liquid crystal display is ± 20 degrees, it was found that the diffuse reflection plate of the reflective liquid crystal display has good reflection characteristics.
Thus, when an optical film or a diffuse reflector is formed using a resin film having surface irregularities by the resin film formation method of the present invention, an optical film having good diffusibility or a reflector having good reflection characteristics is reduced. It was found that it can be produced at a low cost and in a short time. Such a reflector is suitable for a diffuse reflector such as a reflective liquid crystal display.

(Other embodiments)
1. In the present invention, the radical polymerization type ultraviolet curable resin used for forming the uncured resin film may be used by mixing a plurality of types. For example, two or more of the radical polymerization type ultraviolet curable resins of Embodiments 1, 2, 3, and 4 may be mixed and used.
2. Alternatively, an uncured resin film may be formed using such a mixed resin, and the oxygen concentration in the atmosphere around the uncured resin film may be controlled to 20% by volume or more to irradiate ultraviolet rays.
3. In addition, an uncured resin may be formed with a non-uniform film thickness using such a mixed resin, and the oxygen concentration in the atmosphere around the non-cured resin film with a non-uniform film thickness may be 20% by volume or more. You may make it irradiate an ultraviolet-ray by controlling to.
4). Also, using a resin film having an uneven surface formed by combining one or more of using a mixed resin, controlling the oxygen concentration, and making the film thickness of the uncured resin non-uniform, the uneven surface A diffusion reflection plate may be formed by forming a metal film.

It is a schematic perspective view explaining the formation method and apparatus of the resin film of Embodiment 1 of this invention. It is a schematic side view of the stage of the resin film forming apparatus of FIG. It is a top view of the stage of the resin film forming apparatus of FIG. It is a figure explaining hardening of the uncured resin film in Embodiment 1. 3 is a schematic cross-sectional side view illustrating the depth of unevenness on the surface of a resin film formed on a substrate in Embodiment 1. FIG. It is a graph which shows the relationship between the film thickness of the uncured resin film obtained by the method of Embodiment 1, and the depth of surface unevenness. The depth and width of the surface unevenness | corrugation of the resin film obtained from the 15-micrometer-thick uncured resin film in Embodiment 1 are shown. It is a schematic perspective view explaining the formation method and apparatus of the resin film of Embodiment 2 of this invention. It is a schematic perspective view explaining the formation method and apparatus of the resin film of Embodiment 3 of this invention. 10 is a graph showing the relationship between the depth of surface irregularities of a resin film of a sample and the oxygen concentration in Embodiment 3. It is a graph which shows the relationship between the depth of the surface unevenness | corrugation of the resin film of the sample in Embodiment 4, and the film thickness of an uncured resin film. 10 is a graph showing the relationship between the depth of surface irregularities of a resin film of a sample and the film thickness of an uncured resin film in Embodiment 5. It is a figure explaining hardening of the uncured resin film in Embodiment 5. It is a figure explaining hardening of the uncured resin film in Embodiment 6. It is a graph which shows the relationship between the depth of the surface unevenness | corrugation of the resin film of the sample in Embodiment 6, and the film thickness of an uncured resin film. It is a graph which shows the reflective characteristic of the diffuse reflection board obtained by the resin film formation method of this invention.

Explanation of symbols

10, 20 Stage 11 Frame 11a Cavity window portion 11b Positioning pin 12 Height adjusting means 15 Ultraviolet irradiation mechanism 15a Light source body 15b Optical fiber 15c Direct irradiation unit 21 Sealed container 27 Oxygen concentration adjusting means 28 Gas introduction pipe 29 Gas discharge pipe 50 Ultraviolet absorption Agent R Uncured resin R1 Solid-liquid contact surface R2 Surface R3 Surface irregularity S Substrate

Claims (11)

  A resin material containing a radical polymerization type ultraviolet curable resin is applied to an ultraviolet transmissive substrate to form an uncured resin film, and ultraviolet rays are irradiated from the substrate side toward the contact surface between the substrate and the uncured resin film. A resin film forming method, comprising: curing an uncured resin film to form an underlying resin film having irregularities on the surface.   The method for forming a resin film according to claim 1, wherein the film thickness of the uncured resin film is 10 μm or more.   The resin film forming method according to claim 1 or 2, wherein the oxygen concentration in the atmosphere on the surface side of the uncured resin film is adjusted to 20% by volume or more when the ultraviolet rays are irradiated.   The method for forming a resin film according to any one of claims 1 to 3, wherein the radical polymerization type ultraviolet curable resin contains a polyfunctional monomer having three or more functional monomers.   The resin film forming method according to claim 1, wherein the resin material contains an ultraviolet absorbing material.   The resin film forming method according to claim 1, wherein the uncured resin film is formed on the substrate with a non-uniform film thickness.   A stage holding an ultraviolet transmissive substrate having an uncured resin film containing a radical polymerization type ultraviolet curable resin on its surface, and irradiating ultraviolet rays from the substrate side toward the contact surface between the substrate and the uncured resin film And an ultraviolet irradiation mechanism for the resin film forming apparatus.   The resin film forming apparatus according to claim 7, wherein the stage has a window for transmitting ultraviolet rays to a portion on which the substrate is placed.   The resin film forming apparatus according to claim 7 or 8, wherein the stage has an ultraviolet transmissive plate at a portion on which the substrate is placed. The stage accommodates the substrate so that it can be taken in and out, and the part on which the substrate is placed has a sealed container made of an ultraviolet transmitting material,
Furthermore, the resin film formation apparatus of Claim 7 which comprises the oxygen concentration adjustment means for adjusting the oxygen concentration in the said airtight container.   A resin film having an uneven surface formed on a substrate by using the resin film forming method according to claim 1, and a metal film formed on the uneven surface of the resin film. A diffuse reflector characterized by that.

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