JP7568601B2 - Film mold - Google Patents

Description

The present invention relates to a film mold for transferring a concave-convex shape onto the surface of a curable resin material.

Liquid crystal display devices are widely used as display devices for various electronic devices. In recent years, such electronic devices have become increasingly smaller, and there is a demand for smaller and lighter liquid crystal display devices as well.

In such liquid crystal display devices, optical functional sheets that mainly utilize the effects of reflection, refraction, scattering, etc., or sheets that combine these are used. One such optical functional sheet is a shaped film in which a specific uneven shape is given to the surface of a resin film. Such shaped films are usually manufactured by press molding using a mold plate with the desired uneven shape, or by injection molding.

As another method of imparting a predetermined uneven shape to the surface of a resin film, for example, Patent Document 1 proposes a method using a film mold (a release film for molding). In the technology of Patent Document 1, from the viewpoint of releasability from the film material on which the uneven shape is to be formed, a release compound such as a silicone compound or a fluorine compound is used as the material that constitutes the uneven shape of the film mold. On the other hand, Patent Document 2 discloses, in a specific example, a technology that uses poly-4-methylpentene-1 as a release sheet of a thermoplastic resin.

JP 2019-73022 A JP 2001-225376 A

However, in the technology described in Patent Document 1, although the film mold has sufficient releasability for the film material on which the unevenness is to be formed, the wettability is insufficient, and therefore the transferability of the unevenness is not necessarily sufficient. This problem is particularly prominent when a curable resin material is used as the film material on which the unevenness is to be formed. The technology in Patent Document 2 only discloses an embodiment in which poly-4-methylpentene-1 is used as a thermoplastic resin release sheet, and the indicators for selecting an appropriate material are unclear.

The present invention aims to provide a film mold that exhibits good wettability and peelability with respect to curable resin materials and is capable of forming a concave-convex shape on the surface of the curable resin material.

As a result of intensive research into achieving the above-mentioned object, the present inventors have found that the above-mentioned object can be achieved by controlling the surface free energy _SE of the uneven surface and the free volume _SV of the uneven surface, measured by positron annihilation spectroscopy, within predetermined ranges for a film mold made of a resin film with an uneven surface for transferring an uneven shape to the surface of a curable resin material, and have thus completed the present invention.

That is, according to the present invention, there is provided a film mold made of a resin film having an uneven surface for transferring an uneven shape to a surface of a curable resin material, comprising:
There is provided a film mold in which the surface free energy S _E [unit: mN/m] of the uneven surface and the free volume S _V [unit: nm ³ ] of the uneven surface measured by a positron annihilation method satisfy the following formulas (1) to (3).
S _E >35.7 (1)
S _V > 0 (2)
S _E <-296.77×S _V +77.371 (3)

The film mold of the present invention is preferably a long film obtained by imparting a continuous or intermittent uneven surface to a resin film formed by melt extrusion.
Alternatively, the film mold of the present invention is preferably a long film obtained by continuously or intermittently applying an ultraviolet-curable resin to the surface of a substrate film and curing the resin to impart an uneven shape to the surface.
The film mold of the present invention preferably has an average thickness of 10 to 200 μm.

The present invention provides a film mold that exhibits good wettability and peelability with respect to curable resin materials and can effectively form uneven shapes on the surface of the curable resin material.

FIG. 1 is a diagram showing an example of a shaped film manufacturing apparatus using a film mold according to an embodiment of the present invention. FIG. 2 is a graph showing the relationship between surface free energy _SE and free volume _SV of the resin films according to the examples and comparative examples.

Figure 1 is a diagram showing an example of a shaped film manufacturing apparatus using a film mold according to an embodiment of the present invention. In the following, the manufacturing apparatus shown in Figure 1 will be mainly used as an example for explanation, but the present invention is not particularly limited to the embodiment shown in Figure 1.

In the manufacturing apparatus shown in FIG. 1, first, a substrate film 40 is continuously fed from a substrate feed roll 10, and the substrate film 40 passes through a guide roll 11 and is then coated on its surface by a T-die 20, forming a curable resin material layer 50 on its surface. The thickness of the curable resin material layer 50 is controlled by adjusting the clearance formed by the T-die 20 and the nip roll 12 and the feeding speed.

The manufacturing device shown in FIG. 1 is configured so that the film mold 60 is continuously fed from the film mold feed roll 13. The base film 40 on which the curable resin material layer 50 is formed and the film mold 60 are superimposed by the lamination roll 15 and the upstream backup roll 16. Here, the film mold 60 has a predetermined uneven shape on the surface side facing the curable resin material layer 50, and the base film 40, the curable resin material layer 50, and the film mold 60 are superimposed in this order to form a laminate in a state in which the surface having the predetermined uneven shape is in contact with the curable resin material layer 50.

Then, the laminate in which the base film 40, the curable resin material layer 50, and the film mold 60 are stacked in this order is irradiated with ultraviolet light by the ultraviolet irradiation device 30, so that the curable resin material constituting the curable resin material layer 50 is cured in a state in which the predetermined uneven shape formed on the surface of the film mold 60 is transferred, thereby forming a cured resin layer 50a having a desired uneven shape on its surface. Next, after undergoing a curing reaction by ultraviolet irradiation, the film mold 60 passes between the laminating roll 15 and the downstream backup roll 17, and the film mold 60 is peeled off from the base film 40 having the cured resin layer 50a. The film mold 60 is then wound up by the film mold winding roll 14, and the base film 40 having the cured resin layer 50a is wound up by the base material winding roll 19 via the guide roll 18.

According to the manufacturing apparatus shown in FIG. 1, the substrate film 40 having the cured resin layer 50a is continuously produced in the manner described above. The substrate film 40 having the cured resin layer 50a thus produced has a desired uneven shape on its surface due to the transfer of the predetermined uneven shape formed in the film mold 60, and is therefore used as a shaping film, and is suitable for various optical applications, for example, as an optical functional sheet utilizing the effects of reflection, refraction, scattering, etc.

In this embodiment, the film mold 60 is a resin film having an uneven surface, in which the surface free energy S _E [unit: mN/m] of the uneven surface and the free volume S _V [unit: nm ³ ] of the uneven surface measured by a positron annihilation method satisfy the following formulas (1) to (3).
S _E >35.7 (1)
S _V > 0 (2)
S _E <-296.77×S _V +77.371 (3)

The film mold 60 only needs to have an uneven shape formed on at least one surface such that the surface free energy S _E and the free volume S _V satisfy the above formulas (1) to (3), and such an uneven shape may be formed on both surfaces.

In this embodiment, the film mold 60 is laminated onto the base film 40 on which the curable resin material layer 50 is formed, with the uneven shape of the film mold 60 pressed against the surface of the curable resin material layer 50. While maintaining this state, the curable resin material constituting the curable resin material layer 50 is cured by ultraviolet irradiation, thereby forming a cured resin layer 50a in which the uneven shape of the film mold 60 is transferred.

According to the present embodiment, by using as the film mold 60 a resin film in which the surface free energy S _E of the uneven surface and the free volume S _V of the uneven surface satisfy the above formulas (1) to (3), the film mold 60 can be made to exhibit good wettability with respect to the curable resin material constituting the curable resin material layer 50 and to exhibit excellent peelability, thereby making it possible to satisfactorily form the cured resin layer 50a having the desired uneven shape.

In particular, the present inventors have conducted research into the resin material constituting the film mold 60, and have obtained the following findings. That is, if a resin material with excellent releasability is used as the resin material constituting the film mold 60, the wettability with respect to the curable resin material constituting the curable resin material layer 50 deteriorates, the material does not wet uniformly, and air bubbles are easily trapped between the film mold 60 and the curable resin material layer 50. Such air bubbles become defects, and the cured resin layer 50a having the desired uneven shape cannot be formed. On the other hand, if a resin material with excellent wettability with respect to the curable resin material constituting the curable resin material layer 50 is selected, the adhesion to the curable resin material becomes too strong, the releasability deteriorates, and there is a problem that the shape of the cured resin layer 50a is damaged during peeling.

In response to this, the present inventors conducted further studies and found that by setting the surface free energy S _E of the uneven surface and the free volume S _V of the uneven surface within the ranges that satisfy the above formulas (1) to (3), the film mold 60 can be made to exhibit good wettability with respect to the curable resin material that constitutes the curable resin material layer 50 and to exhibit excellent peelability, and that this makes it possible to satisfactorily form a cured resin layer 50a having a desired uneven shape.

In the film mold 60, the surface free energy S _E of the uneven surface and the free volume S _V of the uneven surface may satisfy the above formulas (1) to (3). However, in order to achieve a higher balance between wettability and releasability with respect to the curable resin material that constitutes the curable resin material layer 50, it is preferable that they satisfy any one or all of the following formulas (4) to (6), and it is more preferable that they satisfy any one or all of the following formulas (7) to (9).
40≦ _SE ≦60 (4)
0.06≦S _V ≦0.1 (5)
-296.77×S _V +67≦S _E ≦-296.77×S _V +77 (6)

If the surface free energy S _E of the uneven surface is less than 35.7 N/m, the wettability to the curable resin material that constitutes the curable resin material layer 50 will be deteriorated, making it easier for air bubbles to become trapped between the film mold 60 and the curable resin material layer 50, and it will be impossible to form a cured resin layer 50a having the desired uneven shape.

When the free volume S _V of the uneven surface is preferably 0.06 ^nm3 or more, the permeability of the curable resin material constituting the curable resin material layer 50 into the film mold 60 can be increased, and this makes it possible to ensure sufficient adhesion required for molding. From the viewpoint of further improving the releasability, it is more preferable that 0.06≦S _V ≦0.08.

Furthermore, if S _E > −296.77 × S _V + 77.371, the adhesion to the curable resin material will be too strong, resulting in poor peelability. During peeling, the shape of the cured resin layer 50 a will be damaged, making it impossible to form a cured resin layer 50 a having the desired uneven shape.

The surface free energy S _E of the uneven surface of the film mold 60 can be calculated from the measured contact angle data by measuring the contact angles of water, diiodomethane, and ethylene glycol on the uneven surface of the film mold 60, using the analytical theory of Kitazaki and Hata. The free volume S _V of the uneven surface can be determined by measuring the uneven surface of the film mold 60 using a positron annihilation method. The positron annihilation method is a type of positron annihilation lifetime measurement method, which measures the time from when a positron is incident on a sample until it annihilates, and calculates the free volume of pores from the annihilation lifetime.

The average thickness of the film mold 60 is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 100 μm, and even more preferably 30 to 60 μm. By setting the average thickness of the film mold 60 within the above range, a cured resin layer 50a having a desired uneven shape can be produced with higher productivity. Examples of uneven shapes that can be produced using a film mold include continuous or intermittent shapes with a height of 1 to 30 μm, an aspect ratio of 0.5 to 1.0, and an interval of 0 to 20 times the height.

The method for producing the film mold 60 is not particularly limited, but examples thereof include a method in which a resin film is obtained by melt extrusion, the obtained resin film is heated, and the film is pressed against a shaping roll having a predetermined uneven shape formed on its surface to form an uneven shape continuously or intermittently on the surface to obtain a long film. The heating temperature of the resin film when pressed against the shaping roll having a predetermined uneven shape formed on its surface is not particularly limited, but examples thereof include a method in which the resin film is heated to a temperature equal to or higher than the glass transition temperature of the resin material that constitutes the resin film.

Alternatively, the film mold 60 can be manufactured by continuously or intermittently applying an ultraviolet-curable resin to the surface of a resin film that serves as the base film, and then curing the resin to form an uneven shape using the ultraviolet-curable resin, thereby obtaining a long film with an uneven surface.

The resin material constituting the resin film forming the film mold 60 is not particularly limited, but is preferably a thermoplastic resin, for example, polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), acrylic resins such as polymethyl methacrylate (PMMA), carbonate resins such as polycarbonate (PC), amide resins such as nylon 6, cyclic olefin resin (COP), ethylene-vinyl alcohol copolymer (EVOH), polyphenylene sulfide (PPS), etc. Two or more of these may be laminated or mixed.

When using a method of forming the uneven shape using an ultraviolet curing resin, the ultraviolet curing resin can be a radical curing acrylic monomer, an acrylic oligomer such as urethane acrylate, epoxy acrylate, or polyester acrylate, an unsaturated polyester, or a cationic curing epoxy resin, oxetane resin, or vinyl ether. The substrate film used in this case can be made of the above-mentioned resin materials.

The method for setting the surface free energy S _E of the uneven surface of the film mold 60 and the free volume S _V of the uneven surface within the above range is not particularly limited, but examples thereof include a method for selecting a resin material constituting the resin film forming the film mold 60, a method for modifying the surface by corona treatment, a method for adjusting wettability by a surface modifier, a method for adjusting the free volume by adding inorganic fine particles, and a method for adjusting the crystallinity when the resin material is a crystalline resin. In particular, in the case of a crystalline resin such as polyethylene terephthalate, the free volume S _{V can be reduced without changing the surface free energy S E by} increasing the crystallinity by controlling the heating conditions and the stretching conditions when forming the film, and increasing the number of dense molecular arrangement parts.

The curable resin material constituting the curable resin material layer 50 is not particularly limited, and may be either a thermosetting resin or an ultraviolet curing resin, but ultraviolet curing resin is preferred from the viewpoint of excellent production efficiency. The ultraviolet curing resin may be the same resin as that exemplified when forming the uneven shape of the film mold with an ultraviolet curing resin, and is not particularly limited, but an acrylic resin with good transparency is preferred from the viewpoint of imparting optical functionality. Furthermore, when applying a curable resin material to the surface of the T-die 20 in the manufacturing apparatus shown in FIG. 1, it is more preferable that the resin is a solventless ultraviolet curing resin (a resin that has a viscosity that can be applied even without a solvent). In addition, when a thermosetting resin is used as the curable resin material constituting the curable resin material layer 50, a heating device such as a heater may be used instead of the ultraviolet irradiation device 30 shown in FIG. 1, and the resin may be cured by heating.

From the viewpoint of better transferring the uneven shape by the film mold 60, the curable resin material constituting the curable resin material layer 50 preferably has a viscosity (B-type viscosity) at a temperature of 25°C before curing of 10 to 600 cps, more preferably 20 to 100 cps, and even more preferably 20 to 70 cps, and it is preferable that the viscosity of the curable resin material in a state in which it does not substantially contain a solvent is within this range. Furthermore, when a solventless ultraviolet curable resin is used, by having the viscosity in a state in which it does not substantially contain a solvent within this range, it is possible to achieve excellent coatability when coating with the T-die 20 in the manufacturing apparatus shown in FIG. 1.

The average thickness of the curable resin material layer 50 before curing and the average thickness of the cured resin layer 50a after curing are not particularly limited and may be appropriately selected depending on the characteristics and application of the resulting shaped film, but are preferably 1 to 100 μm, more preferably 5 to 20 μm.

The base film 40 is not particularly limited, but when an ultraviolet-curable resin is used as the curable resin material constituting the curable resin material layer 50, or when the base film 40 having the final cured resin layer 50a is used for optical purposes, a light-transmitting resin film is preferred. Examples of resin materials constituting such a resin film include acrylic resins, polycarbonate resins, acrylic-modified polycarbonate resins, and cyclic olefin resins.

The average thickness of the base film 40 is not particularly limited and may be selected appropriately depending on the characteristics and application of the resulting shaped film, but is preferably 10 to 200 μm, and more preferably 20 to 40 μm.

According to the present embodiment, the film mold 60 is a resin film in which the surface free energy S _E of the uneven surface and the free volume S _V of the uneven surface satisfy the above formulas (1) to (3). Such a film mold 60 exhibits good wettability and peelability with respect to the curable resin material that constitutes the curable resin material layer 50, and therefore it is possible to satisfactorily form a cured resin layer 50a having a desired uneven shape on its surface.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.
The evaluation methods for each characteristic are as follows.

<Surface free energy S _E >
The contact angles of water, diiodomethane, and ethylene glycol on the resin film surface were measured using a fully automatic contact angle meter (product name "DM-701", manufactured by Kyowa Interface Science Co., Ltd.) under the following conditions, and the surface free energy S _E [unit: mN/m] was calculated using the Kitazaki-Hata method.
Measurement temperature: 25±2°C
Measurement humidity: 50±10%RH
Amount of liquid: 3 μL
Retention time after liquid contact: 10 seconds

<Free volume S _V >
The resin film was attached to a 15 mm×15 mm silicon wafer and degassed in vacuum at 25° C. The positron annihilation lifetime was measured using the sample under the following conditions.
Measurement equipment: Fuji Invac small positron annihilation generator PALS-200A
Positron source: ^22Na -based positron annihilation Gamma ray detector: _BaF2 scintillator and photomultiplier tube Beam intensity: 5 keV
Measurement temperature: 25°C
Measurement atmosphere: vacuum Total count number: about 5,000,000 counts Then, a three-component analysis was performed on the obtained positron annihilation lifetime curve using the nonlinear least squares program POSITRONFIT, and the annihilation lifetimes were designated τ ₁ , τ ₂ , and τ ₃ in ascending order of the annihilation lifetime. From the longest average annihilation lifetime τ ₃ , the free volume radius R ₃ was calculated using the following formula, and the free volume S _V [unit: nm ³ ] of the film surface was calculated from the obtained free volume radius R ₃ .
τ ₃ = (1/2) [1-{R ₃ / (R ₃ +0.166)} + (1/2π) sin {2πR ₃ / (R ₃ +0.166)}] ^-1
S _V = (4/3)π(R ₃ ) ³

<Peel strength>
A sample having a width of 25 mm and a length of 150 mm was prepared using a laminate of a resin film as the substrate 40, a cured acrylic resin film as the cured resin layer 50a, and a resin film to become the film mold 60. A 90° peel test was performed on the adhesive surface between the cured acrylic resin film as the cured resin layer 50a and the resin film to become the film mold 60 using a tensile tester (product name "Tensilon Universal Material Tester RTC-1210A", manufactured by ORIENTEC Corporation) to measure the 90° peel strength [unit: N/25 mm]. From the viewpoint of being able to peel well when used as a film mold, a sample with a 90° peel strength of 2 N/25 mm or less was judged to pass.

<Presence or absence of air bubbles>
The laminate of the resin film as the substrate 40, the cured acrylic resin film as the cured resin layer 50a, and the resin film that would become the film mold 60 was visually inspected for the presence or absence of air bubbles at the interface therebetween.

Example 1
The surface free energy _SE and free volume _SV of a non-stretched polybutylene terephthalate resin film (IV=1.0, melt extrusion at 260° C. to a thickness of 40 μm) were measured by the above-mentioned method. The results are shown in Table 1.

Next, an acrylic resin (product name "PAK-02", manufactured by Toyo Gosei Co., Ltd., B-type viscosity at 25°C: 70 cps or less) was applied to the surface of a polyester film with an easy-adhesion layer (product name "Cosmoshine A4300", manufactured by Toyobo Co., Ltd., thickness 38 μm) as the substrate 40 using a bar coater to form an acrylic resin layer having a thickness of 10 μm as the curable resin material layer 50. Then, a polybutylene terephthalate resin film to be the film mold 60 was laminated on the surface of the acrylic resin layer side of the laminate formed by forming an acrylic resin layer as the curable resin material layer 50 on the surface of the polyester film with an easy-adhesion layer as the substrate 40 obtained in this way, and then, by using a UV irradiation device from the polyester film with an easy-adhesion layer as the substrate 40, curing with a UV irradiation amount of 971 mJ / cm ² was performed to obtain a laminate of the polyester film with an easy-adhesion layer as the substrate 40, the cured acrylic resin film as the cured resin layer 50a, and the polybutylene terephthalate resin film to be the film mold 60, and the peel strength and the presence or absence of air bubbles were measured according to the above-mentioned method. The results are shown in Table 1.

<Examples 2 to 10>
Except for using the resin films shown in Table 1 as the resin films to be the film mold 60, the surface free energy _SE and the free volume _SV were measured in the same manner as in Example 1, and a laminate of a polyester film with an easy-adhesion layer as the substrate 40, a cured acrylic resin film as the cured resin layer 50a, and a resin film to be the film mold 60 was obtained in the same manner as in Example 1, and the peel strength and the presence or absence of air bubbles were measured in the same manner. The results are shown in Table 1.

The resin films used in Examples 2 to 10 are as follows:
Example 2 (PBT (2)): Biaxially stretched polybutylene terephthalate resin film (product name "BOBLET BO-PBT", manufactured by Kohjin Film & Chemicals Co., Ltd., thickness 25 μm)
Example 3 (PBT (3)): A polybutylene terephthalate resin film obtained by forming a polybutylene terephthalate resin (product name "GelaNex 700FP", manufactured by Polyplastics Co., Ltd.) into a film having a thickness of 40 μm by melt extrusion at 250° C. Example 4 (Nylon 6): Nylon 6 film (product name "Harden N1100", manufactured by Toyobo Co., Ltd., thickness 20 μm)
Example 5 (PPS): Polyphenylene sulfide resin film (product name "TORELINA", manufactured by Toray Industries, Inc., thickness 100 μm)
Example 6 (EVOH): Ethylene-vinyl alcohol copolymer resin film (product name "EVAL", manufactured by Kuraray Co., Ltd., thickness 20 μm)
Example 7 (COP): Cycloolefin resin film (product name "ZEONOR", manufactured by Zeon Corporation, thickness 130 μm)
Example 8 (PMMA (1)): A polymethyl methacrylate resin film obtained by biaxially stretching a film formed by melt extrusion of polymethyl methacrylate resin (average molecular weight = 120,000 to 150,000, glass transition temperature = 124 ° C.) to a thickness of 40 μm. Example 9 (PMMA (2)): A polymethyl methacrylate resin film obtained by biaxially stretching a film formed by melt extrusion of polymethyl methacrylate resin (average molecular weight = 90,000 to 110,000, glass transition temperature = 122 ° C.) to a thickness of 40 μm. Example 10 (PET (1)): A polyethylene terephthalate resin film (IV = 0.9 modified with 15 mol of isophthalic acid) was formed into a film of 100 μm thickness by melt extrusion at 270 ° C., and then biaxially stretched and heat set to obtain a polyethylene terephthalate resin film with a high degree of crystallinity (1730 cm The degree of crystallinity calculated from the half-width (Δν) of ⁻¹ was 43.68% (degree of crystallinity=100×((305−Δν)/209−1.335)/(1.455−1.335)).

<Comparative Examples 1 to 9>
Except for using the resin films shown in Table 1 as the resin films to be the film mold 60, the surface free energy _SE and the free volume _SV were measured in the same manner as in Example 1, and a laminate of a polyester film with an easy-adhesion layer as the substrate 40, a cured acrylic resin film as the cured resin layer 50a, and a resin film to be the film mold 60 was obtained in the same manner as in Example 1, and the peel strength and the presence or absence of air bubbles were measured in the same manner. The results are shown in Table 1.

The resin films used in Comparative Examples 1 to 9 are as follows:
Comparative Example 1 (PP (1)): Unstretched polypropylene film (product name "RXC22", manufactured by Mitsui Chemicals Tocello, thickness 20 μm)
Comparative Example 2 (PP(2)): Unstretched polypropylene film obtained by melt-extruding polypropylene resin (homo-PP) to a thickness of 200 μm. Comparative Example 3 (PP(3)): Unstretched polypropylene film obtained by melt-extruding polypropylene (trade name "SunAllomer", manufactured by SunAllomer Co., Ltd.) to a thickness of 100 μm at 260° C. Comparative Example 4 (PE): Low-density polyethylene film (thickness 100 μm)
Comparative Example 5 (PTFE): Polytetrafluoroethylene film (product name "Naflon", manufactured by Nichias Corporation, thickness 100 μm)
Comparative Example 6 (TPX): Polymethylpentene resin film (product name "Opulent X-44B", manufactured by Mitsui Chemicals, Inc., thickness 20 μm)
Comparative Example 7 (PET (2)): Polyethylene terephthalate resin film (product name "Cosmoshine A4100", manufactured by Toyobo Co., Ltd., thickness 38 μm)
Comparative Example 8 (PET (3)): Amorphous polyethylene terephthalate resin film obtained by forming a polyethylene terephthalate resin (IV = 0.9, modified with 15 mol of isophthalic acid) into a film having a thickness of 100 μm by melt extrusion at 270 ° C. (crystallinity calculated from the half-width (Δν) at 1730 cm ⁻¹ which changes depending on the crystallinity by Raman spectroscopy was 0.88% (crystallinity = 100 × ((305 - Δν) / 209 - 1.335) / (1.455 - 1.335))
Comparative Example 9 (PC(1)): A polycarbonate resin film obtained by forming a polycarbonate resin (product name "Iupilon 7022J", manufactured by Mitsubishi Engineering Plastics Corporation) into a film having a thickness of 100 μm by melt extrusion at 280° C.

As shown in Table 1, when a resin film having a surface free energy S _E and a free volume S _V that satisfy the formulas (1) to (3) (formula (1): S _E > 35.7, formula (2): S _V > 0, formula (3): S _E < -296.77 x S _V + 77.371 ) was used as the film mold 60, the peel strength against the cured acrylic resin as the cured resin layer 50a was low, the releasability was excellent, and the generation of air bubbles was suppressed, showing good wettability (Examples 1 to 10).
In addition, the spectrum of the interface between the cured resin layer and the film mold was measured by Raman spectroscopy, and the penetration depth of the cured resin was calculated from the intensity ratio of the specific peak. As a result, the penetration depth of the cured resin into the resin film of Example 3 was 0 μm. Furthermore, the penetration depth of the cured resin into the resin film of Comparative Example 9 was 4 μm, and the deeper the penetration depth, the stronger the peel strength tended to be. The measurement results of the penetration depth are shown in Table 1. In Table 1, "N.D." indicates that it was difficult to separate the peaks and measure the penetration depth.

<Penetration depth>
The penetration depth was measured under the following conditions.
Measurement device: Laser Raman spectrophotometer (product name "NRS-5500", manufactured by JASCO Corporation)
Laser wavelength: 532.31 nm
Laser spot diameter: 2 μm
The specific measurement method was as follows: A cross section of a laminate of a resin film serving as the substrate 40, a cured acrylic resin film serving as the cured resin layer 50a, and a resin film serving as the film mold 60 was measured at multiple points in the thickness direction across the interface between the cured resin layer 50a and the film mold 60 using a laser Raman spectrophotometer.
Then, for the measurement spectrum obtained at each thickness position, among the measurement peaks originating from the resin film to be the film mold 60, the measurement peaks that do not overlap with the measurement peaks originating from the cured acrylic resin film as the cured resin layer 50a and have the highest intensity were selected from the measurement peaks that are less affected by the orientation state of the resin film, and the ratio P1/P2 of the intensity P1 of the measurement peak that has the highest intensity among the other measurement peaks was calculated. The position where the ratio P1/P2 is stably small is regarded as the cured resin layer 50a, and the position where the ratio P1/P2 is stably large is regarded as the film mold 60, and the range in which the value of the ratio P1/P2 changes as the thickness direction between them is specified, and this range is regarded as the region where the cured acrylic resin as the cured resin layer 50a has penetrated into the resin film to be the film mold 60, and the width of this range was calculated as the penetration depth.

In addition, when a metal shaping roll having an uneven surface pattern was used to obtain a resin film having an uneven surface (uneven height: 8-12 μm, uneven aspect ratio: 0.7-1.0) for the resin film of Example 3, similar results were obtained when the resin film having an uneven surface was used. Therefore, from these results, it can be said that the resin films of Examples 1-10, when used as a film mold 60, exhibit good wettability and peelability with respect to the curable resin material, and can be used to favorably form an uneven surface on the surface of the curable resin material.

On the other hand, when the surface free energy S _E of the resin film that becomes the film mold 60 does not satisfy formula (1) (formula (1): S _E > 35.7), air bubbles are generated between the resin film that becomes the film mold 60 and the layer made of the cured acrylic resin as the cured resin layer 50a, resulting in poor wettability (Comparative Examples 1 to 6).
Furthermore, when the surface free energy S _E and the free volume S _V of the resin film that becomes the film mold 60 do not satisfy formula (3) (formula (3): S _E < -296.77 × S _V + 77.371), the peel strength becomes too high and the peelability to the cured resin layer 50 a is poor (Comparative Example 7). In particular, in Comparative Examples 8 and 9, the result was that broken material was generated during peeling.
FIG. 2 shows a graph of the relationship between the surface free energy _SE and the free volume _SV of the resin films according to the respective examples and comparative examples.

10 to 19... roll 20... T-die 30... ultraviolet ray irradiation device 40... substrate film 50... curable resin material layer 50a... cured resin layer 60... film mold

Claims (2)

A film mold made of a resin film having an uneven surface for transferring an uneven shape to a surface of a curable resin material,
a surface free energy S _E [unit: mN/m] of the uneven surface and a free volume S _V [unit: nm ³ ] of the uneven surface measured by a positron annihilation method satisfy the following formulas (1) to (3):
A film mold is a long film obtained by continuously or intermittently imparting an uneven surface to a resin film formed by melt extrusion .
S _E >35.7 (1)
S _V > 0 (2)
S _E <-296.77×S _V +77.371 (3) The film mold according to claim 1 , which has an average thickness of 10 to 200 μm.

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