KR102517502B1 - Optical film with antifouling layer - Google Patents

Abstract

An optical film (F) with an antifouling layer of the present invention includes a transparent base material (10) and an antifouling layer (30) sequentially in the thickness direction (T). The ratio of F to Si detected by elemental analysis by X-ray photoelectron spectroscopy on the surface 31 side opposite to the transparent substrate 10 in the antifouling layer 30 is 20 or more at an analysis depth of 1 nm am.

Description

Optical film with antifouling layer

The present invention relates to an optical film with an antifouling layer.

From the viewpoint of antifouling property, for example, an optical film with an antifouling layer is bonded to the outer surface on the image display side in displays such as touch panel displays. An optical film with an antifouling layer includes a transparent substrate and an antifouling layer disposed on an outermost surface of one side of the transparent substrate. The antifouling layer suppresses the adhesion of contaminants such as hand oil on the surface of the display, and facilitates removal of the contaminants adhering. A technology related to an optical film with such an antifouling layer is described in, for example, Patent Document 1 below.

Japanese Unexamined Patent Publication No. 2020-52221

At the time of use of the optical film on which the antifouling layer is formed, contaminants adhering to the antifouling layer are removed by, for example, a wiping operation. However, repetition of the wiping operation for the antifouling layer causes a decrease in antifouling properties of the antifouling layer. From the viewpoint of the antifouling function of the optical film on which the antifouling layer is formed, deterioration in the antifouling properties of the antifouling layer is undesirable.

The present invention provides an optical film with an antifouling layer suitable for suppressing a decrease in the antifouling property of the antifouling layer.

In the present invention [1], a transparent substrate and an antifouling layer are sequentially provided in the thickness direction, and the antifouling layer is detected by elemental analysis by X-ray photoelectron spectroscopy on the surface side opposite to the transparent substrate in the antifouling layer An optical film with an antifouling layer having a ratio of F to Si of 20 or more at an analysis depth of 1 nm.

The present invention [2] includes the optical film with an antifouling layer described in [1] above, wherein the ratio in the antifouling layer monotonically decreases from an analysis depth of 1 nm to an analysis depth of 5 nm.

This invention [3] includes the optical film with an antifouling layer described in [1] or [2] above, wherein the antifouling layer contains an alkoxysilane compound having a perfluoropolyether group.

The present invention [4] includes the optical film with an antifouling layer according to any one of [1] to [3] above, wherein the antifouling layer is a dry coating film.

In the present invention [5], any one of the above [1] to [4], wherein an inorganic oxide base layer is provided between the transparent substrate and the antifouling layer, and the antifouling layer is disposed on the inorganic oxide base layer. It includes an optical film having an antifouling layer described above.

This invention [6] includes the optical film with an antifouling layer described in [5] above, wherein the inorganic oxide underlayer contains silicon dioxide.

In the present invention [7], the antifouling layer according to [5] or [6] above, wherein the surface of the antifouling layer side of the inorganic oxide underlayer has a surface roughness Ra of 0.5 nm or more and 10 nm or less is formed. Including optical film.

As described above, the optical film with an antifouling layer of the present invention has a ratio of F to Si detected by elemental analysis by X-ray photoelectron spectroscopy on the surface side opposite to the transparent substrate in the antifouling layer, It is more than 20 at an analysis depth of 1 nm. Therefore, the optical film with this antifouling layer is suitable for suppressing the fall of the antifouling property of the antifouling layer.

1 is a cross-sectional schematic diagram of an embodiment of an optical film of the present invention.
Fig. 2 is a cross-sectional schematic diagram of a modified example of the optical film of the present invention (this modified example does not include an optical function layer).

As shown in FIG. 1, the optical film F as an embodiment of the optical film with an antifouling layer of the present invention includes a transparent substrate 10, an optical function layer 20, and an antifouling layer 30, It is provided in this order toward one side of the thickness direction T. In the present embodiment, the optical film F includes the transparent base material 10, the adhesive layer 41, the optical function layer 20, and the antifouling layer 30 along one side in the thickness direction T. to be prepared in this order. In addition, the optical film F has a shape extending in a direction (surface direction) orthogonal to the thickness direction T.

The transparent base material 10 is equipped with the resin film 11 and the hard-coat layer 12 in this order toward one side of the thickness direction T in this embodiment.

The resin film 11 is a transparent resin film having flexibility. Examples of the material of the resin film 11 include polyester resins, polyolefin resins, polystyrene resins, acrylic resins, polycarbonate resins, polyethersulfone resins, polysulfone resins, polyamide resins, polyimide resins, and cellulose resins. , norbornene resins, polyarylate resins, and polyvinyl alcohol resins. Examples of the polyester resin include polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate. Examples of the polyolefin resin include polyethylene, polypropylene, and cycloolefin polymer (COP). As a cellulose resin, triacetyl cellulose (TAC) is mentioned, for example. These materials may be used independently, or two or more types may be used together. As the material of the resin film 11, from the viewpoint of transparency and strength, one selected from the group consisting of polyester resins, polyolefin resins and cellulose resins is used, more preferably from the group consisting of PET, COP and TAC The one chosen is used.

The surface of the resin film 11 on the side of the hard coat layer 12 may be subjected to surface modification treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, ozone treatment, primer treatment, gloss treatment, and coupling agent treatment.

The thickness of the resin film 11 is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more, from the viewpoint of strength. The thickness of the resin film 11 is preferably 300 μm or less, more preferably 200 μm or less, from the viewpoint of handleability.

The total light transmittance (JIS K 7375-2008) of the resin film 11 is preferably 80% or more, more preferably 90% or more, still more preferably 95% or more. Such a structure is suitable for securing the transparency required of the optical film (F) when the surface of a display such as a touch panel display is provided with the optical film (F). The total light transmittance of the resin film 11 is, for example, 100% or less.

The hard coat layer 12 is arranged on one side of the thickness direction T of the resin film 11 . The hard coat layer 12 is a layer for preventing scratches from being formed on the exposed surface (upper surface in FIG. 1 ) of the optical film F.

The hard coat layer 12 is a cured product of curable resin composition. Examples of the curable resin contained in the curable resin composition include polyester resins, acrylic resins, urethane resins, acrylic urethane resins, amide resins, silicone resins, epoxy resins, and melamine resins. These curable resins may be used independently and two or more types may be used together. From the viewpoint of ensuring the high hardness of the hard coat layer 12, as the curable resin, an acrylic urethane resin is preferably used.

Moreover, as a curable resin composition, an ultraviolet curing type resin composition and a thermosetting type resin composition are mentioned, for example. Since it can be cured without heating at a high temperature, a UV-curable resin composition is preferably used as the curable resin composition from the viewpoint of being useful for improving the manufacturing efficiency of the optical film (F). The ultraviolet curable resin composition includes at least one selected from the group consisting of ultraviolet curable monomers, ultraviolet curable oligomers, and ultraviolet curable polymers. As a specific example of an ultraviolet curable resin composition, the composition for hard-coat layer formation of Unexamined-Japanese-Patent No. 2016-179686 is mentioned.

The curable resin composition may contain fine particles. Mixing of the fine particles into the curable resin composition is useful for adjusting the hardness, adjusting the surface roughness, adjusting the refractive index, and imparting anti-glare properties to the hard coat layer 12 . Examples of fine particles include metal oxide particles, glass particles, and organic particles. Examples of the material of the metal oxide particles include silica, alumina, titania, zirconia, calcium oxide, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Examples of materials for organic particles include polymethyl methacrylate, polystyrene, polyurethane, acrylic/styrene copolymer, benzoguanamine, melamine, and polycarbonate.

The thickness of the hard coat layer 12 is preferably 1 μm or more, more preferably 3 μm or more, from the viewpoint of securing the hardness of the surface of the antifouling layer 30 by securing the hardness of the hard coat layer 12. Preferably it is 5 micrometers or more. The thickness of the hard coat layer 12 is preferably 50 μm or less, more preferably 40 μm or less, still more preferably 35 μm or less, particularly preferably 30 μm or less, from the viewpoint of ensuring the flexibility of the optical film (F). less than μm.

The surface on the side of the adhesion layer 41 in the hard coat layer 12 may be subjected to surface modification treatment. Examples of the surface modification treatment include plasma treatment, corona treatment, ozone treatment, primer treatment, gloss treatment, and coupling agent treatment. From the viewpoint of ensuring high adhesion between the hard coat layer 12 and the adhesion layer 41, the surface on the side of the adhesion layer 41 in the hard coat layer 12 is preferably subjected to plasma treatment.

The thickness of the transparent substrate 10 is preferably 5 μm or more, more preferably 10 μm or more, still more preferably 20 μm or more, from the viewpoint of strength. The thickness of the transparent substrate 10 is preferably 300 μm or less, more preferably 200 μm or less, from the viewpoint of handleability.

The total light transmittance (JIS K 7375-2008) of the transparent substrate 10 is preferably 80% or more, more preferably 90% or more, still more preferably 95% or more. Such a structure is suitable for securing the transparency required of the optical film (F) when the surface of a display such as a touch panel display is provided with the optical film (F). The total light transmittance of the transparent substrate 10 is, for example, 100% or less.

The adhesive layer 41 is used to secure the adhesion of the inorganic oxide layer (the first high refractive index layer 21 described later in the present embodiment) to the transparent substrate 10 (the hard coat layer 12 in the present embodiment). layer for The adhesive layer 41 is disposed on one side of the thickness direction T of the hard coat layer 12 . Examples of the material of the adhesive layer 41 include metals such as silicon, indium, nickel, chromium, aluminum, tin, gold, silver, platinum, zinc, titanium, tungsten, zirconium, and palladium, and two types of these metals. The above alloys and oxides of these metals are exemplified. Adhesion to both the organic layer (specifically, the hard coat layer 12) and the inorganic oxide layer (specifically, the first high refractive index layer 21 in this embodiment), and the compatibility of the transparency of the adhesive layer 41 From this point of view, as a material for the adhesive layer 41, indium tin oxide (ITO) or silicon oxide (SiOx) is preferably used. When silicon oxide is used as the material of the adhesive layer 41, preferably, SiOx having a smaller oxygen content than the stoichiometric composition is used, and more preferably, SiOx having an x of 1.2 or more and 1.9 or less is used.

The thickness of the adhesive layer 41 is a combination of securing the adhesive force between the hard coat layer 12 and the inorganic oxide layer (the first high refractive index layer 21 in this embodiment) and the transparency of the adhesive layer 41 From this point of view, it is preferably 1 nm or more, and preferably 10 nm or less.

The optical function layer 20 is disposed on one side of the thickness direction T of the adhesive layer 41 . In this embodiment, the optical function layer 20 is an antireflection layer for suppressing the reflected intensity of external light. That is, the optical film (F) is an antireflection film in this embodiment.

The optical function layer 20 (antireflection layer) has a high refractive index layer having a relatively large refractive index and a low refractive index layer having a relatively small refractive index alternately in the thickness direction. In the antireflection layer, the net reflected light intensity is attenuated due to an interference action between reflected lights at a plurality of interfaces in a plurality of thin layers (high refractive index layer, low refractive index layer). Further, in the antireflection layer, an interference effect of attenuating the reflected light intensity can be developed by adjusting the optical film thickness (product of refractive index and thickness) of each thin layer. The optical function layer 20 as such an antireflection layer is specifically, the first high refractive index layer 21, the first low refractive index layer 22, the second high refractive index layer 23, and the second low refractive index It has the layer 24 in this order toward one side of the thickness direction T.

The first high refractive index layer 21 and the second high refractive index layer 23 are each made of a high refractive index material having a refractive index of preferably 1.9 or more at a wavelength of 550 nm. From the viewpoint of coexistence of high refractive index and low absorption of visible light, examples of the high refractive index material include niobium oxide (Nb ₂ O ₅ ), titanium oxide, zirconium oxide, tin-doped indium oxide (ITO), and antimony-doped oxide. Tin (ATO) is exemplified, and niobium oxide is preferably used.

The optical film thickness (product of the refractive index and the thickness) of the first high refractive index layer 21 is, for example, 20 nm or more and, for example, 55 nm or less. The optical film thickness of the second high refractive index layer 23 is, for example, 60 nm or more and, for example, 330 nm or less.

The first low refractive index layer 22 and the second low refractive index layer 24 are each made of a low refractive index material having a refractive index of preferably 1.6 or less at a wavelength of 550 nm. From the viewpoint of both low refractive index and low absorption of visible light, examples of the low refractive index material include silicon dioxide (SiO ₂ ) and magnesium fluoride, and silicon dioxide is preferably used.

The optical film thickness of the first low refractive index layer 22 is, for example, 15 nm or more and, for example, 70 nm or less. The optical film thickness of the second low refractive index layer 24 is, for example, 100 nm or more and, for example, 160 nm or less.

In addition, in the optical function layer 20, the thickness of the first high refractive index layer 21 is, for example, 1 nm or more, preferably 5 nm or more, and, for example, 30 nm or less, preferably less than 20 nm. The thickness of the first low refractive index layer 22 is, for example, 10 nm or more, preferably 20 nm or more, and, for example, 50 nm or less, preferably 30 nm or less. The thickness of the second high refractive index layer 23 is, for example, 50 nm or more, preferably 80 nm or more, and, for example, 200 nm or less, preferably 150 nm or less. The thickness of the second low refractive index layer 24 is, for example, 50 nm or more, preferably 60 nm or more, and, for example, 150 nm or less, preferably 100 nm or less.

The second low-refractive-index layer 24 serves also as an inorganic oxide base layer (inorganic oxide base layer 42) that ensures peeling resistance of the antifouling layer 30 in this embodiment. As a material of such a second low refractive index layer 24, also from the viewpoint of securing adhesion to the antifouling layer 30, silicon dioxide and magnesium fluoride are exemplified, and silicon dioxide is preferably used. From the viewpoint of ensuring peeling resistance of the antifouling layer 30, the thickness of the second low refractive index layer 24 is preferably 50 nm or more, more preferably 65 nm or more, still more preferably 80 nm or more. , particularly preferably 90 nm or more. The copper thickness is, for example, 150 nm or less.

The surface of the inorganic oxide base layer 42 on the side of the antifouling layer 30 may be subjected to surface modification treatment. Examples of the surface modification treatment include corona treatment, plasma treatment, ozone treatment, primer treatment, gloss treatment, and coupling agent treatment.

The surface roughness Ra (arithmetic average surface roughness) of the surface of the inorganic oxide base layer 42 on the antifouling layer 30 side is preferably 0.5 nm or more, more preferably 0.8 nm or more. The copper surface roughness Ra is preferably 10 nm or less, more preferably 8 nm or less. Surface roughness Ra is calculated|required from the observation image of 1 micrometer square by AFM (atomic force microscope), for example.

The antifouling layer 30 is a layer having an antifouling function. The antifouling layer 30 is disposed on one side of the thickness direction T of the inorganic oxide base layer 42 . The antifouling layer 30 has a surface 31 (outer surface) on one side of the thickness direction T. The antifouling function of the antifouling layer 30 includes a function of suppressing the adhesion of contaminants such as hand oil to the exposed surface of the film when the optical film F is used, and a function of making it easy to remove the adhering contaminants. .

As a material of the antifouling layer 30, organic fluorine compounds are mentioned, for example. As the organic fluorine compound, an alkoxysilane compound having a perfluoropolyether group is preferably used. As an alkoxysilane compound which has a perfluoropolyether group, the compound represented by the following general formula (1) is mentioned, for example.

R ¹ -R ² -X-(CH ₂ ) _m -Si(OR ³ ) ₃ (1)

In the general formula (1), R ¹ represents a linear or branched fluoroalkyl group (eg, 1 to 20 carbon atoms) in which one or more hydrogen atoms in the alkyl group are substituted with fluorine atoms, preferably represents a perfluoroalkyl group in which all of the hydrogen atoms of the alkyl group are substituted with fluorine atoms.

R ² represents a structure containing at least one repeating structure of a perfluoropolyether (PFPE) group, and preferably represents a structure containing two repeating structures of a PFPE group. Examples of the repeating structure of the PFPE group include a repeating structure of a linear PFPE group and a repeating structure of a branched PFPE group. As a repeating structure of the linear PFPE group, for example, a structure represented by -(OC _n F _2n ) _p - (n represents an integer of 1 or more and 20 or less, and p is an integer of 1 or more and 50 or less The same below) can be mentioned. Examples of the repeating structure of the branched PFPE group include a structure represented by -(OC(CF ₃ ) ₂ ) _p - and a structure represented by -(OCF ₂ CF(CF ₃ )CF ₂ ) _p -. can The repeating structure of the PFPE group is preferably a repeating structure of a linear PFPE group, more preferably -(OCF ₂ ) _p - and -(OC ₂ F ₄ ) _p -.

R ³ represents an alkyl group having 1 or more and 4 or less carbon atoms, preferably a methyl group.

X represents an ether group, a carbonyl group, an amino group or an amide group, and preferably represents an ether group.

m represents an integer of 1 or greater. In addition, m is preferably an integer of 20 or less, more preferably 10 or less, still more preferably 5 or less.

Among the alkoxysilane compounds having such a perfluoropolyether group, a compound represented by the following general formula (2) is preferably used.

CF ₃ -(OCF ₂ ) _q -(OC ₂ F ₄ ) _r -O-(CH ₂ ) ₃ -Si(OCH ₃ ) ₃ (2)

In general formula (2), q represents an integer of 1 or more and 50 or less, and r represents an integer of 1 or more and 50 or less.

Moreover, the alkoxysilane compound which has a perfluoropolyether group may be used independently, and 2 or more types may be used together.

The ratio of F to Si detected by elemental analysis by X-ray photoelectron spectroscopy of the surface 31 of the antifouling layer 30 (the surface of the antifouling layer 30 on the opposite side to the transparent substrate 10) F/Si, atomic number ratio) is 20 or more, preferably 22 or more, more preferably 24 or more, still more preferably 26 or more, at an analysis depth of 1 nm. The higher the number of fluorine atoms present on the surface 31 of the antifouling layer 30, the higher the ratio. When the antifouling layer 30 contains an alkoxysilane compound having a perfluoropolyether group, the higher the orientation of the copper compounds having the following orientations, and the greater the number of copper compounds having such orientations, the higher the above-mentioned orientation. The ratio is high. With the above orientation, one end of the fluoroalkyl group (preferably, perfluoroalkyl group) in the long chain structure of the compound is located on the surface 31 side, and the other end alkoxysilane structure unit is on the optical function layer 20 side. position, preferably an orientation in which the long chain structure extends along the thickness direction (T).

The ratio of F to Si (F/Si) detected by elemental analysis by X-ray photoelectron spectroscopy of the surface 31 of the antifouling layer 30 is preferably from an analysis depth of 1 nm to an analysis depth of 5 nm. It decreases monotonically. When the antifouling layer 30 contains an alkoxysilane compound having a perfluoropolyether group, the higher the orientation of the copper compound having the above orientation, and the greater the number of the copper compounds having the above orientation, the greater the reduction in monotonicity. The degree of change is great.

Elemental analysis of the antifouling layer 30 by X-ray photoelectron spectroscopy is specifically performed as described later in the Examples. In addition, as a method for adjusting the ratio (F/Si), for example, selection of the type of the organic fluorine compound, adjustment of the content ratio of the organic fluorine compound in the antifouling layer 30, antifouling layer 30 selection of a formation method, selection of a material for the base layer of the antifouling layer 30 (second low refractive index layer 24 in this embodiment), and adjustment of the surface roughness of the surface of the antifouling layer 30 side of the base layer can be heard As a method for adjusting the ratio (F/Si), the formation step of the base layer (the second low refractive index layer 24 in this embodiment) in the antifouling layer 30 and the antifouling layer 30 on the base layer ) in a series of lines by a roll-to-roll method (that is, without winding a work film between both steps), selection of whether to be performed is also mentioned.

In this embodiment, the antifouling layer 30 is a film formed by a dry coating method (dry coating film). As a dry coating method, a sputtering method, a vacuum deposition method, and CVD are mentioned. The antifouling layer 30 is preferably a dry coating film, more preferably a vacuum deposition film.

The material of the antifouling layer 30 contains an alkoxysilane compound having a perfluoropolyether group, and the antifouling layer 30 is a dry coating film (preferably a vacuum deposited film) in the optical function layer 20 It is suitable for ensuring high bonding strength of the antifouling layer 30 to the surface and, therefore, suitable for securing peeling resistance of the antifouling layer 30. The high peeling resistance of the antifouling layer 30 is useful for maintaining the antifouling function of the antifouling layer 30 .

The water contact angle (pure contact angle) of the outer surface 31 of the antifouling layer 30 is 110° or more, preferably 111° or more, more preferably 112° or more, still more preferably 113° or more, particularly preferably It is at least 114°. A configuration in which the water contact angle on the outer surface 31 is so high is suitable for realizing high antifouling properties of the antifouling layer 30 . The animal contact angle is, for example, 130° or less. The water contact angle is determined by forming a water droplet (pure water droplet) having a diameter of 2 mm or less on the outer surface 31 (exposed surface) of the antifouling layer 30 and measuring the contact angle of the water droplet with respect to the surface of the antifouling layer 30. , is saved. The water contact angle of the outer surface 31 is, for example, the composition of the antifouling layer 30, the roughness of the outer surface 31, the composition of the hard coat layer 12, and the optical functional layer of the hard coat layer 12 It can be adjusted by adjusting the surface roughness on the (20) side.

The antifouling layer 30 has a thickness of preferably 1 nm or more, more preferably 3 nm or more, still more preferably 5 nm or more, and particularly preferably 7 nm or more. Such a configuration is suitable for securing the peeling resistance of the antifouling layer 30 . The thickness of the antifouling layer 30 is preferably 25 nm or less, more preferably 20 nm or less, still more preferably 18 nm or less. Such a configuration is suitable for realizing the above water contact angle in the antifouling layer 30 .

The optical film F is prepared by preparing a long transparent substrate 10, and then, for example, in a roll-to-roll system, an adhesive layer 41 and an optical functional layer 20 are placed on the transparent substrate 10. ), and the antifouling layer 30 are laminated sequentially. The optical function layer 20 includes a first high refractive index layer 21, a first low refractive index layer 22, a second high refractive index layer 23 and a second low refractive index layer 24 on the adhesive layer 41. It can be formed by sequentially stacking.

The transparent substrate 10 can be produced by forming the hard coat layer 12 on the resin film 11. The hard coat layer 12 can be formed, for example, by applying a curable resin composition containing a curable resin and optionally fine particles onto the resin film 11 to form a coating film, and then curing the coating film. there is. When curable resin composition contains ultraviolet curable resin, the said coating film is hardened by ultraviolet irradiation. When the curable resin composition contains a thermosetting resin, the coating film is cured by heating.

The exposed surface of the hard coat layer 12 formed on the transparent substrate 10 is subjected to a surface modification treatment as needed (hard coat layer pretreatment step). In the case of plasma treatment as the surface modification treatment, examples of the treatment gas include argon gas and oxygen gas. In addition, the discharge power in the plasma treatment is, for example, 10 W or more, and is, for example, 10000 W or less.

The adhesive layer 41, the first high refractive index layer 21, the first low refractive index layer 22, the second high refractive index layer 23, and the second low refractive index layer 24 are each made of materials by a dry coating method. It can be formed by sequentially forming a film (dry film forming process). As the dry coating method, sputtering method, vacuum evaporation method, and CVD are mentioned, and sputtering method is preferably used.

In the sputtering method, a negative voltage is applied to a target placed on a cathode while gas is introduced into the sputter chamber under vacuum conditions. Thereby, a glow discharge is generated to ionize gas atoms, and the gas ions collide with the target surface at high speed to repel the target material from the target surface, and the repelled target material is deposited on a predetermined surface. From the viewpoint of film formation speed, reactive sputtering is preferred as the sputtering method.

In reactive sputtering, a metal target is used as a target, and a mixed gas of an inert gas such as argon and oxygen (reactive gas) is used as the gas described above. The ratio of oxygen contained in the inorganic oxide to be formed can be adjusted by adjusting the flow rate ratio (sccm) of the inert gas and oxygen.

As a power supply for performing the sputtering method, a DC power supply, an AC power supply, an RF power supply, and an MFAC power supply (an AC power supply having a frequency band of several kHz to several MHz) are exemplified. The discharge voltage in the sputtering method is, for example, 200 V or more, and is, for example, 1000 V or less. In addition, the film formation atmospheric pressure in the sputtering chamber where the sputtering method is performed is, for example, 0.01 Pa or more, and, for example, 2 Pa or less.

The exposed surface of the antireflection layer is subjected to surface modification treatment as needed (base layer pretreatment step). In the case of plasma treatment as the surface modification treatment, examples of the treatment gas include oxygen gas and argon gas, and oxygen gas is preferably used. Further, the discharge power in the plasma treatment is, for example, 10 W or more, preferably 50 W or more, and more preferably 70 W or more. The copper discharge power is, for example, 10000 W or less, preferably 8000 W or less, more preferably 5000 W or less, still more preferably 4000 W or less, and particularly preferably 3000 W or less.

The antifouling layer 30 can be formed by forming a film of the organic fluorine compound described above on the optical function layer 20 (antifouling layer forming step). As a method of forming the antifouling layer 30, a dry coating method is exemplified. As a dry coating method, a vacuum deposition method, sputtering method, and CVD are mentioned, for example, The vacuum deposition method is used preferably.

Preferably, a series of processes from the dry film forming step to the antifouling layer forming step are carried out in one continuous line while the work film is run in a roll-to-roll manner. More preferably, a series of processes from the hard coat layer pretreatment step to the antifouling layer forming step are performed in one continuous line while running the work film in a roll-to-roll manner. During the process in one continuous line, the work film never comes out in the atmosphere and is preferably not wound into a roll shape.

For example, the optical film (F) can be manufactured as described above. As for the optical film (F), the side of the transparent base material 10 is bonded to an adherend through, for example, an adhesive, and is used. As an adherend, the transparent cover arrange|positioned on the image display side in displays, such as a touch panel display, is mentioned, for example.

In the optical film F, as described above, the ratio of F to Si detected by elemental analysis by X-ray photoelectron spectroscopy of the surface 31 of the antifouling layer 30 (F/Si, atomic number ratio) is 20 or more, preferably 22 or more, more preferably 24 or more, still more preferably 26 or more, at an analysis depth of 1 nm. Further, the ratio preferably monotonically decreases from an analysis depth of 1 nm to an analysis depth of 5 nm. These configurations are suitable for expressing excellent antifouling properties on the surface 31 by overlapping expression of high hydrophobicity and high oleophobic properties resulting from the terminal fluoroalkyl group of the organic fluorine compound. Incidentally, the above constitution regarding the ratio (F/Si) is suitable for securing a state in which terminal fluorinated alkyl groups are closely arranged with high orientation on the surface 31. Deterioration of the surface 31 is suppressed as the terminal fluoroalkyl groups are arranged densely with high orientation, and accordingly, the antifouling property of the antifouling layer 30 is suppressed from deterioration.

The optical film (F) may be an optical film other than the antireflection film. As another optical film, a transparent conductive film and an electromagnetic wave shielding film are mentioned, for example.

When the optical film F is a transparent conductive film, the optical function layer 20 of the optical film F includes, for example, a first dielectric thin film, a transparent electrode film such as an ITO film, and a second dielectric film. It is provided in this order toward one side of the thickness direction T. In the optical functional layer 20 having such a laminated structure, visible light transmittance and conductivity are compatible.

When the optical film (F) is an electromagnetic wave shielding film, the optical functional layer 20 of the optical film (F) includes, for example, a metal thin film having electromagnetic wave reflective ability and a metal oxide film alternately in the thickness direction (T). provide In the optical functional layer 20 having such a laminated structure, both shielding against electromagnetic waves of a specific wavelength and visible light transmittance are compatible.

In addition, as shown in FIG. 2, the optical film F does not need to be provided with the optical function layer 20. The optical film F shown in FIG. 2 includes a transparent base material 10 (resin film 11, hard coat layer 12), an adhesive layer 41, an inorganic oxide base layer 42, and an antifouling layer. (30) is provided in this order toward one side of the thickness direction (T). In this modified example, the inorganic oxide base layer 42 is disposed on the adhesive layer 41 .

Example

The present invention will be described concretely by showing examples below. The present invention is not limited to the examples. In addition, specific numerical values such as compounding amounts (contents), physical property values, and parameters described below are described in the above-mentioned "mode for carrying out the invention", and the compounding amounts (contents), physical property values, and parameters corresponding to them are described. etc. can be replaced with the upper limit (numerical value defined as "below" or "less than") or lower limit (numerical value defined as "greater than" or "exceeds") of the description.

[Example 1]

First, a hard coat layer was formed on one side of a long triacetyl cellulose (TAC) film (thickness: 80 µm) as a transparent resin film (hard coat layer forming step). In this step, first, an organo silica sol containing 100 parts by mass of an ultraviolet curable acrylic monomer (trade name "GRANDIC PC-1070", manufactured by DIC) and nano-silica particles (trade name "MEK-ST-L", nano The average primary particle size of the silica particles is 50 nm, the solid content concentration is 30% by mass, manufactured by Nissan Chemical Industries, Ltd.) 25 parts by mass (in terms of nano-silica particles), and a thixotropy-imparting agent (trade name "Lucentite SAN", synthetic smectite that is organic clay) , manufactured by Cope Chemical Co., Ltd.) 1.5 parts by mass of a photopolymerization initiator (trade name "OMNIRAD907", manufactured by BASF) 3 parts by mass, and 0.15 parts by mass of a leveling agent (trade name "LE303", manufactured by Kyoeisha Chemical Co., Ltd.) were mixed, solid content A composition (varnish) having a concentration of 55% by mass was prepared. For mixing, an ultrasonic disperser was used. Then, the composition was applied to one side of the TAC film to form a coating film. Next, after curing this coating film by ultraviolet irradiation, it was dried by heating. In the ultraviolet irradiation, a high-pressure mercury lamp was used as a light source, an ultraviolet ray having a wavelength of 365 nm was used, and the cumulative irradiation light amount was 200 mJ/cm ² . In addition, the heating temperature was 80°C, and the heating time was 3 minutes. This formed a hard coat (HC) layer with a thickness of 6 μm on the TAC film.

Next, while the TAC film on which the HC layer was formed as a work film was run in a roll-to-roll manner, the surface of the HC layer of the film was subjected to plasma treatment in a vacuum atmosphere of 1.0 Pa using a plasma treatment device (HC layer pretreatment step). In this plasma treatment, argon gas was used as the treatment gas, and the discharge power (discharge output) was 150 W.

Next, an adhesion layer and an antireflection layer were sequentially formed on the HC layer of the TAC film on which the HC layer was formed after the plasma treatment (sputter film formation process). Specifically, an indium tin oxide (ITO) layer with a thickness of 1.5 nm as an adhesive layer and a thickness as a first high refractive index layer were formed on the HC layer of the TAC film on which the HC layer was formed by a roll-to-roll sputter film deposition apparatus. A 12 nm Nb ₂ O ₅ layer, a 28 nm thick SiO ₂ layer as the first low refractive index layer, a 100 nm thick Nb ₂ O ₅ layer as the second high refractive index layer, and a thickness 85 as the second low refractive index layer. nm SiO ₂ layers were sequentially formed. In the formation of the adhesion layer, an ITO target is used, argon gas as an inert gas, and oxygen gas as a reactive gas of 10 parts by volume per 100 parts by volume of the argon gas are used, the discharge voltage is set to 400 V, and the air pressure in the film formation chamber is reduced. The ITO layer was formed into a film by MFAC sputtering at a (film forming atmospheric pressure) of 0.2 Pa. In the formation of the first high refractive index layer, a Nb target was used, 100 parts by volume of argon gas and 5 parts by volume of oxygen gas were used, the discharge voltage was set to 415 V, and the deposition pressure was set to 0.42 Pa, by MFAC sputtering. A Nb ₂ O ₅ layer was formed. In the formation of the first low refractive index layer, a Si target was used, 100 parts by volume of argon gas and 30 parts by volume of oxygen gas were used, the discharge voltage was set to 350 V, and the deposition atmospheric pressure was set to 0.3 Pa by MFAC sputtering. A SiO ₂ layer was deposited. In the formation of the second high refractive index layer, a Nb target was used, 100 parts by volume of argon gas and 13 parts by volume of oxygen gas were used, the discharge voltage was set to 460 V, and the deposition pressure was set to 0.5 Pa by MFAC sputtering. A Nb ₂ O ₅ layer was formed. In the formation of the second low refractive index layer, a Si target was used, 100 parts by volume of argon gas and 30 parts by volume of oxygen gas were used, the discharge voltage was set to 340 V, and the deposition atmospheric pressure was set to 0.25 Pa by MFAC sputtering. A SiO ₂ layer was deposited. As described above, on the HC layer of the TAC film on which the HC layer was formed, an antireflection layer (the first high refractive index layer, the first low refractive index layer, the second high refractive index layer, and the second low refractive index layer) was formed through the adhesive layer. layered formation.

Next, the surface of the formed antireflection layer was subjected to plasma treatment in a vacuum atmosphere of 1.0 Pa using a plasma treatment device (base layer pretreatment step). In this plasma treatment, oxygen gas was used as a treatment gas, and the discharge power was 100 W.

Next, an antifouling layer was formed on the antireflection layer (antifouling layer forming step). Specifically, an antifouling layer having a thickness of 8 nm was formed on the antireflection layer by a vacuum deposition method using an alkoxysilane compound containing a perfluoropolyether group as a deposition source. The evaporation source is a solid content obtained by drying "Optool UD509" (a perfluoropolyether group-containing alkoxysilane compound represented by the above general formula (2), solid content concentration: 20% by mass) manufactured by Daikin Industry. In addition, the heating temperature of the evaporation source in the vacuum evaporation method was 260 degreeC.

A series of processes from the HC layer pretreatment step to the antifouling layer formation step described above were carried out in one continuous line while running the work film in a roll-to-roll manner. During this process, the work film never came out in the air.

As described above, the optical film of Example 1 was produced. The optical film of Example 1 is provided with a transparent substrate (resin film, hard coat layer), an adhesive layer, an antireflection layer, and an antifouling layer in this order toward one side in the thickness direction.

[Example 2]

Except for the following, the optical film of Example 2 was produced in the same manner as the optical film of Example 1. The base layer pretreatment step was not performed (that is, the discharge power of the plasma treatment as the base layer pretreatment was set to 0 W). In the antifouling layer forming step (vacuum deposition), a solid obtained by drying "KY1903-1" (a perfluoropolyether group-containing alkoxysilane compound) manufactured by Shin-Etsu Chemical Co., Ltd. was used as a deposition source.

[Comparative Example 1]

An optical film of Comparative Example 1 was produced in the same manner as in the optical film of Example 1, except that the work film was once wound into a roll shape after the base layer pretreatment step and before the antifouling layer formation step.

[Comparative Example 2]

The optical film of Comparative Example 2 was produced in the same manner as the optical film of Example 1 except for the step of forming the antifouling layer. In the antifouling layer formation step of this comparative example, the antifouling layer was formed by a wet coating method. Specifically, first, "Optool UD509" (manufactured by Daikin Kogyo) as a coating agent was diluted with a dilution solvent (trade name "Fluorinert", manufactured by 3M) to prepare a coating liquid having a solid content concentration of 0.1% by mass. Next, a coating liquid was applied by gravure coating to form a coating film on the antireflection layer formed in the sputtering film formation process. Next, this coating film was dried by heating at 60°C for 2 minutes. Thus, an antifouling layer having a thickness of 7 nm was formed on the antireflection layer.

<Analysis of antifouling layer by X-ray photoelectron spectroscopy>

The surface of the antifouling layer of each optical film of Examples 1 and 2 and Comparative Examples 1 and 2 was analyzed by X-ray photoelectron spectroscopy (ESCA). A sample for analysis was prepared by cutting out a size of about 10 mm × 10 mm from an optical film. For the analysis, an X-ray photoelectron spectroscopy device (trade name "Quantum 2000", manufactured by Albac Pi Co., Ltd.) was used. In this analysis, X-ray photoelectron spectroscopy was performed under the following conditions.

X Sailor Here: Monochrome AI Kα

X-ray Setting : 200 ㎛φ (15 kV, 30 W)

Photoelectron extraction angle: 5 degrees, 15 degrees, 30 degrees, 45 degrees relative to the sample surface

In this analysis, the analysis depth was adjusted by adjusting the photoelectron extraction angle. Specifically, the analysis depth is 1 nm by setting the photoelectron extraction angle to 5 degrees, the analysis depth is 2 nm by setting the photoelectron extraction angle to 15 degrees, and the analysis depth is 3 nm by setting the photoelectron extraction angle to 30 degrees. The analysis depth was set to 5 nm by setting the extraction angle to 45 degrees. The elemental analysis results are shown in Table 1. The ratio of F to detected Si is also shown in Table 1.

<water contact angle>

For each optical film of Examples 1 and 2 and Comparative Examples 1 and 2, the contact angle of water on the surface of the antifouling layer was investigated. First, water droplets were formed on the surface of the antifouling layer of the optical film by dropping about 1 µL of pure water. Next, the angle between the surface of the water droplets on the surface of the antifouling layer and the surface of the antifouling layer was measured. For the measurement, a contact angle meter (trade name "DMo-501", manufactured by Kyowa Interface Science Co., Ltd.) was used. The measurement results are shown in Table 1 as the initial water contact angle θ ₀ .

<Eraser sliding test>

For each of the optical films of Examples 1 and 2 and Comparative Examples 1 and 2, the degree of deterioration in antifouling properties of the surface of the antifouling layer was investigated by subjecting them to an eraser sliding test. Specifically, first, a sliding test was conducted in which an eraser was reciprocated while sliding on the surface of the antifouling layer of the optical film. In this test, an eraser (Φ6 mm) manufactured by Minoan was used, the load of the eraser on the surface of the antifouling layer was 1 kg/6 mmΦ, and the sliding distance (one way in reciprocation) of the eraser on the surface of the antifouling layer was 20 mm, the sliding speed of the eraser was 40 rpm, and the number of times the eraser was reciprocated with respect to the surface of the antifouling layer was 3000 reciprocations. Next, the water contact angle at the sliding point of the eraser on the surface of the antifouling layer of the optical film was measured by the same method as the measuring method of the initial water contact angle θ ₀ . The measurement results are shown in Table 1 as the water contact angle θ ₁ after the eraser sliding test.

<evaluation>

In the optical films of Examples 1 and 2, compared to the respective optical films of Comparative Examples 1 and 2, the degree of decrease in the water contact angle on the surface of the antifouling layer was significantly smaller by passing through the eraser sliding test, and therefore, antifouling properties were obtained. The decrease in is significantly small (on the surface of the antifouling layer, the smaller the decrease in the water contact angle, the smaller the decrease in antifouling properties).

The embodiment described above is an illustration of the present invention, and the present invention should not be interpreted limitedly by the embodiment. Modifications of the present invention obvious to those skilled in the art are included in the claims described later.

industrial applicability

The optical film with an antifouling layer of the present invention can be applied to, for example, an antireflection film with an antifouling layer, a transparent conductive film with an antifouling layer, and an electromagnetic wave shielding film with an antifouling layer.

F: Optical film (optical film with antifouling layer)
10: transparent substrate
11: resin film
12: hard coat layer
20: optical functional layer
21: first high refractive index layer
22: first low refractive index layer
23: second high refractive index layer
24: second low refractive index layer
30: antifouling layer
31: surface
41: adhesion layer
42: inorganic oxide under layer
T: thickness direction

Claims (7)

A transparent substrate and an antifouling layer are provided in order in the thickness direction,
Optics with an antifouling layer, wherein the ratio of F to Si detected by elemental analysis by X-ray photoelectron spectroscopy on the surface side opposite to the transparent substrate in the antifouling layer is 20 or more at an analysis depth of 1 nm. film roll. According to claim 1,
The optical film roll with an antifouling layer wherein the ratio in the antifouling layer monotonically decreases from an analysis depth of 1 nm to an analysis depth of 5 nm. According to claim 1 or 2,
An optical film roll with an antifouling layer, wherein the antifouling layer contains an alkoxysilane compound having a perfluoropolyether group. According to claim 1 or 2,
An optical film roll with an antifouling layer, wherein the antifouling layer is a dry coating film. According to claim 1 or 2,
An optical film roll with an antifouling layer, wherein an inorganic oxide underlayer is provided between the transparent substrate and the antifouling layer, and the antifouling layer is disposed on the inorganic oxide underlayer. According to claim 5,
An optical film roll with an antifouling layer, wherein the inorganic oxide underlayer contains silicon dioxide. According to claim 5,
The optical film roll with an antifouling layer, wherein the surface of the inorganic oxide base layer on the side of the antifouling layer has a surface roughness Ra of 0.5 nm or more and 10 nm or less.

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