JP2014202933A - Method for molding fine structure, and molded article and optical component obtained by the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a fine structure in various shapes with high dimensional accuracy on a three-dimensional solid face and a molded article obtained by the method.SOLUTION: A method for forming a fine structure 9 includes steps of: forming a fine structure 4 on a substrate film 1; forming a layer 5 comprising a thermoplastic resin on the fine structure 4 to obtain a laminate; sticking the laminate obtained in the above step to a molding object 7, with the thermoplastic resin 5 side facing the molding object 7; and peeling the substrate 1 where the fine structure 4 is formed in the laminate stuck to the molding object 7, from the molding object.

Description

  The present invention relates to a method for forming a fine structure, and more particularly to a method for forming a fine structure on a three-dimensional solid surface and a molded product obtained by the formation method.

Since a fine structure composed of fine irregularities having a period smaller than the wavelength of light expresses an antireflection function, it has been proposed to provide such an antireflection function by forming such a fine structure on the surface of the lens ( Patent Document 1).
As a method for forming a fine structure on a three-dimensional curved surface such as a lens surface, a method is known in which a flexible film made of metal, oxide, resin, or the like having a fine structure is joined along the curved surface. (Patent Document 2). In this method, a flexible film having a thickness of 10 to 100 μm is bonded to the product surface. Therefore, in a product that requires a dimensional accuracy of 10 μm or less for the concavo-convex structure, there is a dimensional error due to the film thickness of the flexible film in the curved portion. There is a problem that it is difficult to apply because it occurs in the uneven structure. Moreover, it is not realistic to make the thickness of the flexible film 10 μm or less because the handling property of the flexible film is extremely deteriorated.

  On the other hand, as a method of directly forming a fine structure on a curved surface, there is a method of forming nanostructures on the curved surface by an etching method using metal nanoparticles deposited on the curved surface by a vacuum process as a mask (non-patent document). 1). This method forms a microstructure directly on the curved surface of the product, so that it is possible to obtain a molded body with high dimensional accuracy. However, since the metal nanoparticles are spherical, there is a problem that the shape of the microstructure that can be obtained is limited. .

JP 2006-171219 A JP 2004-361635 A

Creation and application of nanoparticles (2008, Frontier Publishing, edited by Toru Yonezawa)

  In order to solve the above-described problems, an object of the present invention is to provide a method for forming microstructures of various shapes on a three-dimensional solid surface with high dimensional accuracy, and a molded product obtained by the formation method.

The present invention for solving the above problems is obtained by the steps of forming a fine structure on a base film, forming a layer made of a thermoplastic resin on the fine structure, and forming the laminate. A step of attaching a laminate composed of a base film on which a microstructure is formed and a layer made of the thermoplastic resin, with the thermoplastic resin side facing the object to be formed, and the object attached to the object to be formed It can be achieved by a method for forming a fine structure characterized by comprising a step of peeling the substrate film on which the fine structure is formed in the laminate.
Here, the “fine structure” in the present invention is a concavo-convex structure in which the difference in height between the adjacent top and bottom is 0.05 μm to 5 μm, and the distance between the adjacent tops is 0.05 μm to 10 μm. is there.

  Further, in the present invention, the step of forming a microstructure on the base film is cured by irradiating with ultraviolet rays in a state where a mold having an inverted shape of the microstructure is pressed against the base film through an ultraviolet curable resin. And a step of forming a microstructure made of an ultraviolet curable resin cured on the base film.

  Moreover, it is preferable that the shape of the surface on which the microstructure of the molded body in the present invention is formed is a three-dimensional solid surface.

  In addition, the step of attaching the laminate to the surface which is a three-dimensional solid surface of the molded body is vacuum forming or pressure forming, the glass transition temperature of the thermoplastic resin is T1 ° C., and the storage elasticity of the base film When the temperature at which the rate is 0.1 MPa is T2 ° C., the temperature of the laminate is preferably in the range of T1 + 20 ° C. to T2 ° C., and vacuum molding or pressure molding or a combination of both is preferably performed.

  Furthermore, the said base film is an unstretched film, and the process of sticking the said laminated body on the three-dimensional solid surface of a to-be-molded body is the temperature range from which the storage elastic modulus of the said base film will be 0.1-10 MPa. Is preferably carried out.

  Further, in the step of attaching the laminate to a molded body, when the microstructure formed on the base film is formed of an ultraviolet curable resin, the step has a storage elastic modulus of the ultraviolet curable resin of 0. It is preferably carried out in a temperature range of 1 to 100 MPa.

  In this invention, it is preferable that the material which forms the surface of a to-be-molded body is the same as the thermoplastic resin of the said laminated body.

  Further, in the step of forming the microstructure using the ultraviolet curable resin on the base film, the microstructure to be formed on the base film is applied to the molded body when the laminate is attached to the molded body. The shape is assumed to follow and be stretched, and the shape is preferably different from the microstructure formed on the molded body.

  Moreover, this invention is a molded article which formed the fine structure in the surface obtained by said formation method of a fine structure. Further, the present invention provides a method for producing a molded body having a microstructure, characterized in that a mold having an inverted shape of the molded product is produced, and then the mold is transferred to obtain a molded body having a microstructure on the surface.

  Moreover, this invention is an optical component which consists of a molded article obtained by the said formation method of the said microstructure from which the said to-be-molded body consists of transparent materials. Moreover, this invention is an optical component which formed the fine structure in the surface obtained by the manufacturing method of the molded object which has the said fine structure.

  According to the present invention, it is possible to easily form a fine structure on the surface of a molded body using a fine structure produced by a known lithography technique. In addition, when the laminate of the present invention is attached to the surface of a molded body having a three-dimensional solid surface, the dimensional change of the molded body is only the film thickness of a layer made of a thermoplastic resin. A molded body having a structure can be produced.

It is a figure which shows the formation process of the fine structure using ultraviolet curable resin. It is a figure which shows the formation process of the microstructure by hot press. It is a figure which shows the process of apply | coating a thermoplastic resin on a microstructure. It is a figure which shows the process of forming a fine structure in the surface of a to-be-molded body using a vacuum pressure forming machine. It is a cross-sectional SEM photograph of the reversal structure of the moth-eye structure formed with the ultraviolet curable resin on the base film in an Example. It is a cross-sectional SEM photograph of the moth eye structure formed on the acrylic lens in an Example. It is a figure which shows the reflectance measurement result of the acrylic lens before and after moth eye structure formation in an Example.

Hereinafter, the present invention will be described based on the illustrated embodiments.
The present invention includes a step of forming a fine structure on a base film, a step of forming a layer made of a thermoplastic resin on the fine structure to form a laminate, and a fine structure obtained in the step. A step of attaching a laminate comprising a base film and a layer made of the thermoplastic resin with the thermoplastic resin side facing the molded body, and among the laminated bodies attached to the molded body, A method for forming a fine structure, comprising a step of peeling a base film on which a fine structure is formed.
Hereinafter, each process will be described.
It should be noted that the size, thickness, dimensions, etc. of each part shown in these drawings are different from the size, thickness, dimensions in the actual fine structure forming process.

  FIG. 1 shows a process for forming a fine structure on a base film using an ultraviolet curable resin. This step is a so-called optical nanoimprint method. The fine structure 4 on the base film 1 is obtained by applying the ultraviolet curable resin 2 on the base film 1, pressing the reverse structure 3 of the fine structure from the ultraviolet curable resin 2 side, and curing by irradiating with ultraviolet rays. be able to. Irradiation with ultraviolet rays may be performed from one or both of the base film 1 and the inversion mold 3 having high transmittance with respect to the wavelength contributing to curing.

  Moreover, the formation process of the fine structure on the base film by hot press is shown in FIG. This step is a so-called thermal nanoimprint method. The fine structure 4 can be formed on the base film 1 by applying pressure after heating the reverse mold 3 having the reverse shape of the fine structure 4 from the base film 1. Furthermore, when producing the base film 1 by extrusion molding, the microstructure 4 can be formed on the surface of the base film 1 at the time of extrusion molding by setting the roll surface shape to the inverted shape of the microstructure 4. The method for forming the microstructure 4 on the surface of the base film 1 may be appropriately selected in view of the required area, the size of the structure, the physical properties of the film, and the like.

  The reversal mold 3 having the reversal shape of the fine structure 4 can be manufactured using a known technique. For example, there are a mask exposure method, an electron beam lithography method, an interference exposure method and the like. In addition, aluminum anodization, which is known as self-organization, and fine particle arrangement, which can deal with a large area, can be used. The fine structure inversion mold 3 may be appropriately selected according to the required area and the size of the fine structure.

When the ultraviolet curable resin 2 is used for forming the fine structure, the storage elastic modulus after curing of the ultraviolet curable resin is preferably 0.1 to 100 MPa, and more preferably 0.1 to 10 MPa. This is because, in the step of attaching a laminate having a fine structure to a molded body, which will be described later, by making the elastic modulus of the ultraviolet curable resin 2 and the base film 1 close to each other, the ultraviolet curable resin 2 and the base film It is because it can prevent that 1 peels. When the storage elastic modulus of the ultraviolet curable resin 2 is outside the above range, the base film 1 and the ultraviolet curable resin are caused by a difference in stress applied to the base film 1 and the ultraviolet curable resin 2 in the step of attaching the fine structure to the molded body. The problem that 2 peels easily occurs.
Moreover, before apply | coating the ultraviolet curable resin 2 on the base film 1, you may give well-known easy adhesion processes, such as a corona treatment and a primer process, to the surface of the base film 1 which apply | coats the ultraviolet curable resin 2. FIG. Thereby, peeling of the ultraviolet curable resin 2 and the base film 1 can be further prevented.

  As the substrate film 1, an unstretched film is preferably used. This is to cause the surface of the molded body having a three-dimensional solid surface to follow while stretching the base film in the step of attaching the laminate having a microstructure to the molded body, which will be described later. In the case of using a film that has already been stretched before the attaching step, the crystallinity of the material of the film generally increases, so that the base film 1 is difficult to stretch and it is difficult to follow the surface of the molded body. Furthermore, since the elongation rates in the stretching direction and the non-stretching direction of the base film 1 are different, problems such as difficulty in stretching the base film 1 is likely to occur.

  Examples of the material of the base film 1 include acrylic resins, polyvinyl chloride, polystyrene, and polycarbonate. What is necessary is just to select the material of the base film 1 suitably according to the magnitude | size and shape of a to-be-molded body. In particular, it is preferable to use a rubber-containing acrylic resin from the viewpoint of workability.

  Examples of the fine structure to be formed include a moth-eye structure, a line and space structure, a pillar structure, a hole structure, and other photonic crystals, a diffraction grating, and the like. Here, the fine structure is a concavo-convex structure in which the difference in height between the adjacent top and bottom is 0.05 μm to 5 μm, and the distance between the adjacent tops is 0.05 μm to 10 μm.

  Next, the process of forming the layer 5 made of a thermoplastic resin on the microstructure will be described. As shown in FIG. 3, in the step of applying the thermoplastic resin on the microstructure 4, first, a solution 6 in which the thermoplastic resin is dissolved is prepared using a solvent that is soluble in the thermoplastic resin. After the solution 6 is uniformly applied on the microstructure 4 using an apparatus such as spin coat, bar coat, spray coat, etc., the solvent is evaporated from the solution 6 to fill the irregularities of the microstructure 4 with the thermoplastic resin. A layer 5 made of a smooth thermoplastic resin is obtained.

  Examples of the thermoplastic resin include acrylic resins, polyvinyl chloride, polystyrene, and polycarbonate, and ketones, esters, chlorinated solvents, and the like can be used as solvents for dissolving the thermoplastic resins. Further, it is necessary to select an unnecessary solvent for the material forming the microstructure 4 as the solvent. This is to prevent the solvent in the solution 6 from dissolving the fine structure 4.

  The thickness of the layer 5 made of a thermoplastic resin is preferably 10 μm or less. This is because, in the step of attaching a laminate comprising a base film 1 and a layer 5 made of a thermoplastic resin, which will be described later, to the molded body, when the thickness is greater than 10 μm, the microstructure 4 formed on the molded body This is because the thickness of the layer constituting the layer becomes 10 μm or more and the dimensional accuracy of the molded body is lowered. Here, in order to produce the layer 5 made of a thermoplastic resin having a thickness of 10 μm or less, the viscosity of the solution 6 is preferably 1.0 cP or less. This is because if the viscosity of the solution 6 is larger than 1.0 cP, it is difficult to form a smooth layer 5 made of a thermoplastic resin having a thickness of 10 μm or less on the microstructure 4.

  Further, before the thermoplastic resin is applied on the microstructure 4, a fluorine-based release agent may be applied on the microstructure 4, and the solution 6 to which the release agent is added is applied on the microstructure 4. You may do it. This improves the releasability of the base film 1 of the laminate and the layer 5 made of thermoplastic resin in the step of peeling the base film 1 from the laminate attached to the molded body, which will be described later. Because.

As shown in FIG. 4, the step of attaching a laminate composed of the base film 1 having the microstructure 4 formed on the surface and the layer 5 made of the thermoplastic resin applied on the microstructure 4 to the molded body 7 is, for example, It is preferable to use a vacuum / pressure forming machine 8. The molded body 7 is fixed in a vacuum / pressure forming machine 8 and is arranged so that the thermoplastic resin 5 side of the laminate and the molded body 7 face each other. After softening the thermoplastic resin 5 of the laminate by hot air or infrared heating, the base film 1 side of the laminate is in a pressurized state, and the thermoplastic resin side of the laminate is in a reduced pressure state, The said laminated body can be affixed on a to-be-molded body.
In addition, when depressurizing the thermoplastic resin side, it does not prevent the base film 1 side from being set to atmospheric pressure. Conversely, when pressurizing the base film 1 side, the thermoplastic resin side is set to atmospheric pressure. It does not prevent it.

  When the glass transition temperature of the thermoplastic resin is T1 ° C. and the temperature at which the storage elastic modulus of the base film 1 is 0.1 MPa is T2 ° C., the laminated body in the step of attaching the laminated body to the molded body 7 The temperature is preferably in the range of T1 + 20 ° C. to T2 ° C., and more preferably in the range of T1 + 40 ° C. to T2 ° C. When the laminate is attached to the molding 7 at a temperature lower than T1 + 20 ° C., the thermoplastic resin of the laminate is insufficiently softened, and the microstructure 4 composed of the layer 5 made of the thermoplastic resin is formed on the molding 7. May not be able to adhere to. On the other hand, when the laminate is affixed to the molded body 7 at a temperature higher than T2 ° C., the base film 1 of the laminate that has been softened by heating may not be able to maintain the film shape.

  Moreover, it is good to perform the pressure which affixes the said laminated body on the to-be-molded body 7 within the range of 200-350 kPa. When the pressure at which the laminate is bonded to the molded body 7 is 200 kPa or less, the laminate does not sufficiently follow the curved surface of the molded body 7 facing the laminated body. It may be difficult to form the structure 4 on the entire curved surface of the molded body 7. On the other hand, when the said laminated body is affixed on the to-be-molded body 7 by the pressure of 350 kPa or more, the base film 1 of the said laminated body may fracture | rupture by a pressure.

  Furthermore, it is preferable that the surface of the molded body 7 is made of a material having high adhesive properties with the thermoplastic resin 5 of the laminate. Examples of the material having high adhesiveness with the thermoplastic resin 5 include acrylic resin, polycarbonate, glass, polystyrene, and microolefin resin. Moreover, you may give well-known easy-adhesion processes, such as a corona process and a primer process, to the surface of the to-be-molded body 7. FIG.

  When the base film 1 is peeled from the laminated body attached to the molded body 7, an inverted structure 9 of the microstructure 4 composed of the layer 5 made of a thermoplastic resin is formed on the surface of the molded body 7. The temperature at which the base film 1 is peeled from the molded body 7 to which the laminate is attached is preferably T1 + 20 ° C. or lower. When the base film 1 is peeled from the molded body 7 to which the laminate is attached at a temperature higher than T1 + 20 ° C., the thermoplastic resin 5 in contact with the molded body 7 is softened, and the molded body 7 And the thermoplastic resin 5 are low in adhesion, the thermoplastic resin 5 is peeled off at the same time as the base film 1, and it may be difficult to form the inverted structure 9 on the surface of the molded body 7.

  In order to improve the adhesion between the layer 5 made of the thermoplastic resin and the molded body 7, among the laminates made of the base film 1 and the layer 5 made of the thermoplastic resin, the thermoplastic is applied to the layer 5 side made of the thermoplastic resin. The adhesive layer may be formed of a material having high adhesion to the resin and the molded body 7. The thickness of the adhesive layer is preferably 1 μm or less. This is because, when the thickness is 1 μm or more, film thickness unevenness occurs in the adhesive layer due to the pressure for adhering the laminated body to the molded body 7, and the dimensional accuracy of the molded body deteriorates. Examples of the material having high adhesiveness to the thermoplastic resin and the molded body 7 include silane coupling agents, epoxy adhesives, acrylic adhesives, and the like.

  When the laminate is attached to the molded body 7, the microstructure follows the stretched body according to the shape of the molded body 7, so that the microstructure 4 formed on the base film 1 of the laminated body is also stretched. . By designing the shape of the microstructure 4 assuming the stretching of the base film 1, desired characteristics can be obtained over the entire surface of the molded body 7.

  You may use the obtained molded object as an optical component. Further, it is possible to perform metal vapor deposition treatment on the molded body so as to increase the functionality such as polarization separation. Furthermore, it is possible to produce an inverted mold by electroforming, and to produce a molded product having a fine structure formed on the surface by transfer that is rich in mass production, such as injection molding or hot press, from the inverted mold.

  A nickel mold (manufactured by Kyodo International Co., Ltd.) having a moth-eye structure with a period of 300 nm and a height of 300 nm was used as the fine mold. A polyvinyl chloride film (Tough Neil, manufactured by Nippon Wavelock Co., Ltd., hereinafter referred to as “PVC”) or a rubber-containing acrylic film (hereinafter referred to as “RT”) was used as the base film. As the rubber-containing acrylic film (RT), the same film as described in Example 1 disclosed in JP-A-2009-228000 was used except that the thickness was 150 μm.

  A mold was attached to the substrate film via an acrylic ultraviolet curable resin UVX4332 (manufactured by Toa Gosei Co., Ltd.) and irradiated with ultraviolet rays. When the mold was peeled from the base film, an inverted structure of a moth-eye structure made of a cured ultraviolet curable resin could be obtained on the base film (see FIG. 5). PMMA (parapet GH, manufactured by Kuraray Co., Ltd.) dissolved and diluted to 5 wt% with methyl isobutyl ketone as a solvent is applied to the inverted structure of the moth-eye structure by spin coating, and the solvent is evaporated by heating to 70 ° C. A resin layer was formed. The temperature T2 at which the storage elastic modulus of the base film becomes 0.1 MPa is 134 ° C. for the polyvinyl chloride film and 177 ° C. for the acrylic film. Moreover, the glass transition temperature T1 of PMMA used as a thermoplastic resin is 90 degreeC.

  A laminate composed of a base material film and a thermoplastic resin that forms an inverted structure of a moth-eye structure on the surface is heated to a predetermined temperature in the range of 100 to 180 ° C. in a vacuum / pressure forming machine (manufactured by Fuse Vacuum) and acrylic at 300 kPa. Affixed to a lens (φ60 mm). After cooling the acrylic lens to which the laminate was attached to room temperature, when the base film was peeled off, it was confirmed that a moth-eye structure made of PMMA was formed on the surface of the acrylic lens. Table 1 shows the test conditions and results. In addition, even in the case of “impossible” in this example, if the shape of the molded body is different from the present example, it may be “possible” under the same conditions. It was.

<Reference Example 7>
Using the same UV curable resin, moth-eye structure and acrylic lens as in the example, vacuum pressure forming at 100 to 180 ° C. using a biaxially stretched PET film (Toyobo Ester, A4300, manufactured by Toyobo) on the substrate film Carried out. As a result, the film was broken at the time of vacuum / pressure forming at any temperature, and the microstructure 4 could not be formed.

  As a result of observing a molded body in which a moth-eye structure (see FIG. 6) was formed on the surface of the acrylic lens obtained in Example 4, the moth-eye structure was stretched by 0 to 30% from the top to the bottom of the lens. Further, as shown in FIG. 7, the surface reflectance of the acrylic lens before and after the formation of the moth eye was measured with a microspectroscope (made by Lambda Vision), and the reduction of the reflectance due to the formation of the moth eye structure was confirmed.

  An inversion mold was produced by performing an electroforming process from a molded body in which a moth-eye structure was formed on the surface of the acrylic lens obtained in Example 4. When injection molding was performed from the reversal mold, a molded body having the same optical performance as the molded body obtained in Example 4 was obtained.

DESCRIPTION OF SYMBOLS 1 Base film 2 Ultraviolet curable resin 3 Micro structure reversal type 4 Micro structure 5 Layer made of thermoplastic resin 6 Solution which diluted thermoplastic resin with solvent 7 Molded object 8 Vacuum pressure molding machine 9 Micro structure reversal structure

Claims (12)

Forming a microstructure on the substrate film;
Forming a layer of a thermoplastic resin on the microstructure to form a laminate;
A step of attaching a laminate composed of a base film on which the microstructure obtained in the step is formed and a layer made of the thermoplastic resin, with the thermoplastic resin side facing the molded body; and
A method for forming a fine structure, comprising: a step of peeling a base film on which the fine structure is formed from the laminate attached to the object to be formed from the object to be formed. The step of forming a microstructure on the base film is a step of curing the UV curable resin by UV irradiation in a state where a mold having an inverted shape of the microstructure is pressed against the base film through the UV curable resin. 2. The method for forming a fine structure according to claim 1, which is a step of forming a fine structure made of an ultraviolet curable resin cured on a film. The method for forming a fine structure according to claim 1 or 2, wherein a shape of the surface on which the fine structure of the molded body is formed is a three-dimensional solid surface. The step of attaching the laminate to the body to be molded is a step by vacuum forming or pressure forming, and the glass transition temperature of the thermoplastic resin is T1 ° C., and the storage elastic modulus of the base film is 0.1 MPa. 4. The method for forming a microstructure according to claim 3, wherein when T2 ° C. is set, vacuum forming or pressure forming is performed with the temperature of the laminated body in a range of T1 + 20 ° C. to T2 ° C. 5. The base film is an unstretched film, and the step of attaching the laminate to the three-dimensional surface of the molded body is performed in a temperature range where the storage elastic modulus of the base film is 0.1 to 10 MPa. The method for forming a microstructure according to any one of claims 1 to 4, wherein: In the step of affixing the laminate to the molded body, the microstructure formed on the base film is formed of an ultraviolet curable resin, and the storage elastic modulus of the ultraviolet curable resin is 0.1 to 100 MPa. The method for forming a microstructure according to any one of claims 1 to 5, wherein: The method for forming a microstructure according to any one of claims 1 to 6, wherein the thermoplastic resin of the laminate is the same as a material forming the surface of the molded body. In the step of forming the fine structure on the base film, the fine structure to be formed on the base film is a shape that is assumed to be stretched in the step of attaching the laminate to the target object, and 4. The method for forming a fine structure according to claim 3, wherein the shape is different from the fine structure formed on the body. A molded product obtained by the method for forming a microstructure according to any one of claims 1 to 8. A mold having an inverted shape of the molded article is produced from a molded article having a microstructure on the surface obtained by the method for forming a microstructure according to any one of claims 1 to 8, and then the mold is transferred. The manufacturing method of the molded object which has a microstructure characterized by obtaining the molded object which has a microstructure on the surface by this. The optical component comprising the molded product according to claim 9, wherein the molded body is made of a transparent material. The optical component obtained by the manufacturing method of the molded object of Claim 10.