Patent Application
20230126941
The present invention relates to an antiglare film-attached transparent substrate, and particularly relates to an antiglare film-attached transparent substrate that is suitably used in combination with an image display apparatus.
A transparent substrate such as a glass sheet disposed on an image display side of an image display apparatus such as a liquid crystal display apparatus may have an antiglare function in order to reduce specular reflection of ambient light. The antiglare function can be exhibited by minute unevenness. The antiglare function is evaluated by using gloss as an index such that the less the value is, the more excellent the antiglare function is. Meanwhile, light scattering generated by the minute unevenness is evaluated by haze. The haze is preferably low in order not to degrade clarity of a displayed image.
A technique of forming, on a transparent substrate, a film having minute unevenness on a surface and imparting the antiglare function has been known. Patent Literature 1 discloses an antiglare film-attached substrate in which an antiglare film including two kinds of particles and a silica-based matrix is formed on a glass sheet. The antiglare film contains first particles and second particles, and a ratio of the mass of the second particles to the mass of the first particles is in a range of 0.5 to 4 (paragraph 0038). The average aspect ratio of the first particles is 10 to 80, and the first particle typically has a plate-like shape. The average aspect ratio of the second particles is 1 to 5, and the second particle typically has a spherical shape. In this film, the specific orientation of the first particles is hindered due to the second particles being present, and the first particles are randomly oriented with respect to the principal surface of the glass sheet (
Patent Literature 1 discloses the technique on the assumption that the technique is used for solar cell modules and the like as well as image display apparatuses. Therefore, the technique is not optimized for use in combination with an image display apparatus. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a novel antiglare film-attached transparent substrate that is suitably used on an image display side of an image display apparatus.
The present invention provides an antiglare film-attached transparent substrate that includes
a transparent substrate and an antiglare film disposed on the transparent substrate, and, in the antiglare film-attached transparent substrate,
the antiglare film contains particles and a matrix, and
the matrix contains silicon oxide.
According to a first embodiment of the present invention,
an antiglare film-attached transparent substrate includes
a transparent substrate, and an antiglare film disposed on the transparent substrate, and, in the antiglare film-attached transparent substrate,
the antiglare film contains particles and a matrix,
the particles are substantially formed of flat-plate-shaped particles,
a thickness of each of the flat-plate-shaped particles is in a range of 0.3 nm to 3 nm, and an average diameter of principal surfaces of the flat-plate-shaped particles is in a range of 10 nm to 1000 nm,
the matrix contains silicon oxide, and
the principal surfaces of the flat-plate-shaped particles are disposed substantially parallel to a principal surface of the transparent substrate in the antiglare film.
According to a second embodiment of the present invention,
an antiglare film-attached transparent substrate includes
a transparent substrate, and an antiglare film disposed on the transparent substrate, and, in the antiglare film-attached transparent substrate,
the antiglare film contains particles and a matrix,
the particles are substantially formed of phyllosilicate mineral particles,
the matrix contains silicon oxide, and
in phyllosilicate mineral contained in the phyllosilicate mineral particles in the antiglare film,
a crystal plane oriented along a principal surface of the transparent substrate is a (001) plane.
According to a third embodiment of the present invention,
an antiglare film-attached transparent substrate includes
a transparent substrate, and an antiglare film disposed on the transparent substrate, and, in the antiglare film-attached transparent substrate,
the antiglare film contains particles and a matrix, and
the matrix contains silicon oxide and a nitrogen atom.
According to a fourth embodiment of the present invention,
an antiglare film-attached transparent substrate includes
a transparent substrate, and an antiglare film disposed on the transparent substrate, and, in the antiglare film-attached transparent substrate
the antiglare film contains particles and a matrix,
the matrix contains silicon oxide, and
the antiglare film incudes a first region in which the particles are stacked in a thickness direction of the film, and a valley-shaped second region that surrounds the first region or that is surrounded by the first region.
The present invention can provide an antiglare film-attached transparent substrate that is suitable for allowing image display of an image display apparatus to be favorably viewed.
Embodiments of the present invention will be described below. The following description is not intended to limit the present invention to specific embodiments. In the description herein, “substantially parallel” means that an angle between two subject surfaces is preferably less than or equal to 30°, more preferably less than or equal to 20°, and particularly preferably less than or equal to 10°. “Main component” means that the content is preferably greater than or equal to 50% by mass and more preferably greater than or equal to 80% by mass. “Substantially formed of” means that the content is preferably greater than or equal to 80% by mass, more preferably greater than or equal to 90% by mass, and particularly preferably greater than or equal to 95% by mass. “Principal surface” of a substrate represents a front surface and a rear surface other than side surfaces, and more specifically represents a surface on which a film is formed. “Principal surface” of a flat-plate-shaped particle has a similar meaning, and represents a pair of front and rear surfaces of the flat-plate-shaped particle. The definition of “plateau-shaped” will be described below with reference to
(Particle)
The particles 1 may be flat-plate-shaped particles. The particles 1 may be substantially formed of flat-plate-shaped particles. However, a part of the particles 1 may have shapes other than flat-plate-like shapes, for example, have spherical shapes. The shapes, and a preferable average particle diameter and material of the spherical particles are as described for a third embodiment. The particles 1 may be merely formed of flat-plate-shaped particles without containing spherical particles and the like.
A thickness 1t of the particle 1 corresponds to a distance between the paired principal surfaces 1s, and is in a range of 0.3 nm to 3 nm. The thickness 1t is preferably greater than or equal to 0.5 nm and more preferably greater than or equal to 0.7 nm, and is preferably less than or equal to 2 nm and more preferably less than or equal to 1.5 nm. In a case where the thickness 1t varies depending on a portion, the thickness 1t may be determined as an average of the greatest thickness and the smallest thickness.
An average diameter d of the principal surface 1s of the particle 1 is in a range of 10 nm to 1000 nm. The average diameter d of the principal surface is preferably greater than or equal to 20 nm and more preferably greater than or equal to 30 nm. The average diameter d is preferably less than or equal to 700 nm and more preferably less than or equal to 500 nm. The average diameter d of the principal surface 1s can be determined as an average of the greatest value and the smallest value of diameters passing through the centroid of the principal surface 1s.
The average aspect ratio of the particles 1 can be calculated by d/t. The average aspect ratio is, but is not particularly limited to, preferably greater than or equal to 30 and more preferably greater than or equal to 50. The average aspect ratio may be preferably less than or equal to 1000 and more preferably less than or equal to 700.
The particles 1 may be phyllosilicate mineral particles. A phyllosilicate mineral contained in the phyllosilicate mineral particles is also referred to as sheet silicate mineral. Examples of the phyllosilicate mineral include: kaolin minerals such as kaolinite, dickite, nacrite, and halloysite; serpentine such as chrysotile, lizardite, and amesite; dioctahedral smectite such as montmorillonite and beidellite; trioctahedral smectite such as saponite, hectorite, and sauconite; dioctahedral mica such as muscovite, paragonite, illite, and celadonite; trioctahedral mica such as phlogopite, annite, and lepidolite; dioctahedral brittle mica such as margarite; trioctahedral brittle mica such as clintonite and anandite; dioctahedral chlorite such as donbassite; 2·3 octahedral chlorite such as cookeite and sudoite; trioctahedral chlorite such as clinochlore and chamosite; pyrophyllite; talc; dioctahedral vermiculite; and trioctahedral vermiculite. The phyllosilicate mineral particles preferably contain a mineral belonging to smectite, kaolin, or talc. As the mineral belonging to smectite, montmorillonite is preferable. Montmorillonite belongs to monoclinic system, kaolin belongs to triclinic system, and talc belongs to monoclinic system or triclinic system.
In the antiglare film 10, the principal surface 1s of the particle 1 is disposed substantially parallel to the principal surface 10s of the transparent substrate 10. In a case where the percentage of the particles 1 disposed substantially parallel to the principal surface 10s is greater than or equal to 80%, more preferably greater than or equal to 85%, and particularly preferably greater than or equal to 90% in terms of the number, the principal surface 1s is regarded as being disposed substantially parallel to the principal surface 10s as a whole even if the remaining particles 1 are not disposed substantially parallel to the principal surface 10s. In order to determine this, it is preferable that disposition of 30 flat-plate-shaped particles and preferably 50 flat-plate-shaped particles is checked.
In a case where the particles 1 are phyllosilicate mineral particles, the crystal plane of the phyllosilicate mineral which is oriented along the principal surface 10s of the transparent substrate 10 may be the (001) plane. The plane orientation can be confirmed through X-ray diffraction analysis.
(Matrix)
The matrix 2 contains silicon oxide that is an oxide of Si, and preferably contains silicon oxide as a main component. The matrix 2 containing silicon oxide as a main component is suitable for reducing a refractive index of the film and reducing reflectance of the film. The matrix 2 may contain a component other than silicon oxide and may contain a component partially containing silicon oxide.
The component partially containing silicon oxide is, for example, a component which contains a moiety formed by a silicon atom and an oxygen atom, and in which an atom other than a silicon atom and an oxygen atom, a functional group, or the like is bound to the silicon atom or the oxygen atom in this moiety. Examples of the atom other than a silicon atom and an oxygen atom include a nitrogen atom, a carbon atom, a hydrogen atom, and metal element described in the subsequent paragraph. Examples of the functional group include an organic group represented as R in the subsequent paragraph. Such a component is not strictly silicon oxide since the component is not merely formed of a silicon atom and an oxygen atom. However, in order to describe the characteristics of the matrix 2, it is proper to handle, as “silicon oxide”, the silicon oxide moiety formed of a silicon atom and an oxygen atom, and this also matches the common practice in this field. In the description herein, the silicon oxide moiety is also handled as silicon oxide. As is apparent from the above description, an atomic ratio between the silicon atoms and the oxygen atoms in the silicon oxide may not necessarily be stoichiometric (1:2).
The matrix 2 may contain a metal oxide other than silicon oxide, specifically, may contain a metal oxide component or a metal oxide moiety containing matter other than silicon. The metal oxide that can be contained in the matrix 2 is, but is not particularly limited to, for example, an oxide of at least one metal element selected from the group consisting of Ti, Zr, Ta, Nb, Nd, La, Ce, and Sn. The matrix 2 may contain an inorganic compound component other than an oxide, for example, may contain nitride, carbide, halide, or the like. The matrix 2 may contain an organic compound component.
The metal oxide such as silicon oxide can be formed from a hydrolyzable organic metal compound. Examples of a hydrolyzable silicon compound include compounds represented by formula (1).
RnSiY4-n (1)
R represents an organic group including at least one selected from an alkyl group, a vinyl group, an epoxy group, a styryl group, a methacryloyl group, and an acryloyl group. Y represents a halogen atom or a hydrolyzable organic group that is at least one selected from an alkoxy group, an acetoxy group, an alkenyloxy group, and an amino group. The halogen atom is preferably Cl. n represents an integer of 0 to 3, and is preferably 0 or 1.
R preferably represents an alkyl group, for example, a C1 to C3 alkyl group and particularly preferably represents a methyl group. Y preferably represents an alkoxy group, for example, a C1 to C4 alkoxy group, and a methoxy group and an ethoxy group are particularly preferable. Two or more of the compounds represented by the above-described formula may be used in combination. Examples of such a combination include a combination of tetraalkoxysilane in which n represents 0 and monoalkyltrialkoxysilane in which n represents 1.
The compound represented by formula (1) forms a network structure in which silicon atoms are bound to each other via an oxygen atom after hydrolysis and polycondensation. In this structure, the organic group represented by R is contained in a state of being bound directly to the silicon atom.
(Antiglare Film)
A ratio of the particles 1 to the matrix 2 in the antiglare film 20 is, for example, 0.05 to 10, preferably 0.05 to 7, and more preferably 0.05 to 5 in terms of mass. A volume ratio of voids in the antiglare film 20 may be, but is not particularly limited to, greater than or equal to 10% and more preferably 10 to 20%. Voids may not necessarily be present.
A film thickness of the antiglare film 20 is, but is not particularly limited to, for example, 50 nm to 1000 nm, more preferably 100 nm to 700 nm, and particularly preferably 100 nm to 500 nm from the viewpoint of, for example, properly obtaining antiglare properties with ease. In order to allow the principal surfaces of flat-plate-shaped particles to be oriented substantially parallel to the substrate, the film thickness of the antiglare film 20 is preferably less than or equal to the above-described upper limit. The tendency of randomly orienting the flat-plate-shaped particles is enhanced in a thick film
A surface 20s of the antiglare film 20 preferably has minute unevenness. However, the orientation of the particles 1 along the principal surface 10s of the transparent substrate 10 inhibits development of the unevenness of the surface 20s. A first preferable surface roughness of the surface 20s is represented by Ra, and is preferably 20 nm to 120 nm, more preferably 30 nm to 110 nm, and even more preferably 40 nm to 100 nm. A second preferable surface roughness is represented by Ra, and is preferably 80 nm to 500 nm, more preferably 100 nm to 400 nm, and even more preferably 100 nm to 300 nm. Ra represents an arithmetic average roughness of a roughness profile as defined in JIS B0601:2001. In a case where particles are randomly oriented as in Patent Literature 1, Ra indicates a value greater than values in the above-described range.
Rsm of the surface 20s is greater than 0 μm and is less than or equal to 35 μm, more preferably 1 μm to 30 μm, and even more preferably 2 μm to 20 μm. Rsm represents an average length of roughness profile elements as defined in JIS B0601:2001. When Rsm is not excessively great, so-called sparkle is preferably reduced.
The sparkle represents a bright spot generated depending on relationship between the minute unevenness for imparting the antiglare function and a pixel size of an image display apparatus. The sparkle is observed as irregular light fluctuation according to shift of relative positions between a viewpoint of a user and an image display apparatus. The sparkle has become more significant according to enhancement of preciseness of the image display apparatus. The antiglare film 20 having Ra and Rsm in the above-described ranges is particularly suitable for reducing the gloss and haze in a well-balanced manner while reducing the sparkle.
(Transparent Substrate)
As the transparent substrate 10, a resin sheet or a glass sheet is suitable. The glass of the glass sheet may be general-purpose soda-lime glass or the other glass such as borosilicate glass, aluminosilicate glass, or alkali-free glass. The glass sheet may be a glass sheet formed by a known production method such as a float method or a down-draw method. By such a production method, a glass sheet having a smooth surface can be obtained. The glass sheet may have unevenness on the principal surface, and may be, for example, figured glass. The figured glass can be formed by a production method called a roll-out method. The figured glass produced by this production method has cyclic unevenness in one direction along the principal surface of the glass sheet, in general.
As the resin sheet, for example, an acrylic resin sheet typified by a polymethyl methacrylate sheet or polycarbonate sheet is suitable. Similarly to the glass sheet, the resin sheet may also have unevenness on the principal surface while having a smooth principal surface. In order to impart the unevenness, surface treatment may be performed on the resin sheet. Examples of the surface treatment include oxidation treatment such as corona discharge treatment, plasma treatment, chromic acid treatment (wet), flame treatment, hot air treatment, and ozone/ultraviolet irradiation, sandblasting, and solvent treatment.
Although a thickness of the transparent substrate 10 is not particularly limited, the transparent substrate 10 is preferably thin in a case where the weight is to be reduced. The thickness of the transparent substrate 10 is, for example, 0.4 mm to 5 mm, preferably 0.3 mm to 5 mm, more preferably 0.5 to 3 mm and 0.4 to 3 mm, and particularly preferably 0.6 to 2.5 mm and 0.5 to 2.5 mm. Ra of the principal surface 10s of the transparent substrate 10 may be preferably less than or equal to 10 nm, more preferably less than or equal to 5 nm, even more preferably less than or equal to 2 nm, and particularly preferably less than or equal to 1 nm. In this case, an antiglare effect is significantly exhibited by the antiglare film 20.
Although the transparent substrate 10 may be a flat plate in general, the transparent substrate 10 may be a curved plate. Particularly, in a case where an image display surface of an image display apparatus to be used in combination has a non-flat surface such as a curved surface, the transparent substrate 10 preferably has a non-flat-surface-shaped principal surface corresponding thereto. In this case, the entirety of the transparent substrate 10 may be bent with a constant curvature, or may be locally bent. The principal surface 10s of the transparent substrate 10 may be, for example, formed by connecting a plurality of planes to each other at the curved surfaces. A curvature radius of the transparent substrate 10 is, for example, less than or equal to 5000 mm. The curvature radius is, for example, greater than or equal to 10 mm. However, in particular, the curvature radius may be less than that at a locally bent portion, and is, for example, greater than or equal to 1 mm.
The antiglare film 20 may be formed so as to cover the entirety of the principal surface 10s of the transparent substrate 10 or cover a part of the surface 10s. In the latter case, the antiglare film 20 may be formed in at least a portion of the principal surface 10s which covers an image display surface of an image display apparatus.
In a case where the transparent substrate 10 is a glass sheet, the glass sheet is preferably strengthened glass. The strengthening treatment of a glass sheet includes thermal tempering and chemical strengthening, and chemical strengthening treatment is suitable for a thin glass sheet. In the chemical strengthening treatment, a glass sheet is immersed in molten salt containing alkali metal ions at a temperature lower than or equal to a strain point of glass of the glass sheet, and alkali metal ions (for example, sodium ions) in a surface layer of the glass sheet are exchanged for alkali metal ions (for example, potassium ions) having relatively large ion radii to generate compressive stress on the surface layer of the glass sheet. The chemical strengthening treatment for the glass sheet may be performed before or after the antiglare film is formed. Thermal tempering can also be performed by a known method.
(Optical Characteristics)
Gloss can be evaluated by specular glossiness. 60° specular glossiness of the transparent substrate 10 is, for example, preferably 60 to 130%, more preferably 70 to 120%, and particularly preferably 80 to 110% and 85 to 100%. Hereinafter, “%” of the value of the gloss may be omitted. The specular glossiness represents a value measured for the surface 10s on which the antiglare film 20 is formed. A haze ratio of the transparent substrate is, for example, preferably less than or equal to 20%, more preferably less than or equal to 15%, and particularly preferably less than or equal to 10%, and may be 1 to 8%, more preferably 1 to 6%, and particularly preferably 1 to 5% depending on cases.
The 60° specular glossiness G and the haze ratio H (%) preferably satisfy a relational expression (a), more preferably satisfy a relational expression (b), and even more preferably satisfy a relational expression (c). G and H may satisfy a relational expression (d).
H≤−0.2 G+25 (a)
H≤−0.2 G+24.5 (b)
H≤−0.2 G+24 (c)
H≤−0.15 G+18 (d)
The gloss can be measured in accordance with “Method 3 (60° specular gloss)” in “Specular glossiness-Methods of measurement” of JIS Z8741-1997, and the haze can be measured in accordance with JIS K7136:2000.
In the entire region of the antiglare film 30, the particles 5 are stacked in the film thickness direction. Meanwhile, the antiglare film 40 includes a region 40a in which the particles 5 are stacked in the film thickness direction and a region 40b in which the particles 5 are not stacked in the film thickness direction or the particles 5 do not exist. The region 40b may be a region having a surface 40s which is substantially parallel to the principal surface 10s of the transparent substrate 10 and at which the particles 5 are not exposed, instead of a region in which the particles 5 are not stacked in the film thickness direction or the particles 5 do not exist. The region 40b may extend, for example, preferably over 0.25 μm2 or more, more preferably over 0.5 μm2 or more, and particularly preferably over 1 μm2 or more. In at least a part of the antiglare film 30 and the region 40a of the antiglare film 40, the particles 5 are stacked up to a height that is greater than or equal to 5 times the average particle diameter of the particles 5, and more preferably greater than or equal to 7 times the average particle diameter thereof.
(Particles)
The shape of the particle 5 is, but is not particularly limited to, preferably a spherical shape. The particles 5 may be substantially formed of spherical particles. However, a part of the particles 5 may have shapes other than spherical shapes, for example, may have flat-plate-like shapes. The particles 5 may be merely formed of spherical particles. In the description herein, the spherical particle refers to a particle in which a ratio of the longest diameter passing through the centroid to the shortest diameter passing therethrough is greater than or equal to 1 and less than or equal to 1.8, and particularly preferably greater than or equal to 1 and less than or equal to 1.5, and the surface is formed as a curved surface. The average particle diameter of the spherical particles may be preferably 5 nm to 200 nm, more preferably 10 nm to 100 nm, and particularly preferably 20 nm to 60 nm. The average particle diameter of the spherical particles is determined as the average of the particle diameters, specifically, as the average of average values between the above-described shortest diameters and longest diameters, and is preferably measured by using 30 particles, preferably by using 50 particles, based on an SEM image.
Preferable ranges of the thickness t of each of the flat-plate-shaped particles which may be partially contained in the particles 5, and the average diameter d and the aspect ratio d/t of the principal surface thereof are set as described for the first and the second embodiments.
Although a material of the particles 5 is not particularly limited, the particles 5 preferably contain metal oxide, in particular, silicon oxide. The metal oxide may contain, for example, an oxide of at least one metal element selected from the group consisting of Ti, Zr, Ta, Nb, Nd, La, Ce, and Sn.
The particles 5 can be fed to the antiglare films 30 and 40 from a dispersion liquid of the particles 5. In this case, a dispersion liquid in which each particle 5 is independently dispersed is preferably used. As compared with a dispersion liquid in which particles are connected in a chain-like manner, a dispersion liquid in which particles are not aggregated is suitably used in order to achieve a preferable aggregated state of particles in the antiglare films 30 and 40. The particles 5 that are independent from each other are easily moved according to volatilization of liquid such as a dispersion medium, and are easily aggregated so as to be suitable for achieving preferable characteristics in the film.
(Matrix)
The matrix 2 is as described for the first and second embodiments. However, in the third embodiment, the matrix 2 preferably contains a nitrogen atom. The nitrogen atom is preferably contained as a part of an organic compound component or a functional group, in particular, a part of a nitrogen-atom-containing functional group. The nitrogen-atom-containing functional group is preferably an amino group. Particularly, the nitrogen atom can be a part of functional groups having high reactivity in a material for forming a matrix that contains, as a main component, metal oxide such as silicon oxide. Such a functional group can contribute to promoting aggregation of the particles 5 in film formation to aggregate the particles 5 in a preferable aggregated state.
The metal oxide such as silicon oxide can be formed from a hydrolyzable organic metal compound. Examples of the hydrolyzable silicon compound include compounds represented by formula (1).
The nitrogen atom can also be fed to the antiglare films 30 and 40 from a compound containing silicon atoms, specifically from an amino-group-containing silane coupling agent. This compound can be represented by, for example, formula (2).
AkBmSiY4-k-m (2)
A represents an organic group containing an amino group. The amino group may be any of primary, secondary, and tertiary amino groups. A represents, for example, an amino-group-containing hydrocarbon, and preferably represents an alkyl group or an alkenyl group in which amino groups are substituted for a part of the atoms, more preferably represents an alkyl group or an alkenyl group in which an amino group is substituted for a hydrogen atom, and particularly preferably represents an alkyl group or an alkenyl group having an amino group at its terminal. Each of the alkyl group and the alkenyl group may have either a linear chain form or a branched form. Preferable specific examples of A include ω-aminoalkyl group having an amino group at a terminal of an alkyl group, and N-ω′-(aminoalkyl)-ω-aminoalkyl group in which a hydrogen atom of the amino group is substituted by another aminoalkyl group. A preferably contains a carbon atom as an atom connecting to the silicon atom. In this case, a hydrocarbon group typified by an alkyl group and an alkenyl group can be disposed between the nitrogen atom and the silicon atom. In other words, the nitrogen atom may be bound to the silicon atom forming silicon oxide via the hydrocarbon group. A particularly preferably represents a γ-aminopropyl group or an N-(2-aminoethyl)-3-aminopropyl group.
B may represent the organic group described above as R, and may represent an alkyl group or an alkenyl group. The alkyl group or the alkenyl group may have a branched form or may include substitution for a part of hydrogen atoms in the alkyl group or the alkenyl group. B preferably represents an alkyl group having no substituted moiety, and more preferably represents a linear alkyl group, and the number of carbon atoms in the carbon chain is 1 to 3 and B even more preferably represents a methyl group. Y is as described above. k represents an integer of 1 to 3, m represents an integer of 0 to 2, and k+m represents an integer of 1 to 3. k represents 1, and m represents 0 or 1. In a case where A represents a γ-aminopropyl group, k=1 and m=0 are preferably satisfied. In a case where A represents an N-(2-aminoethyl) aminopropyl group, k=1 and m=0 or 1 are preferably satisfied.
The compound represented by formula (2) forms a network structure in which silicon atoms are bound to each other via an oxygen atom after hydrolysis and polycondensation. In a case where the compound represented by formula (1) is used in combination, the compound represented by formula (2) forms a part of the network structure. In this structure, the organic group represented by A is contained in a state of being bound directly to the silicon atom.
The organic group represented by A is considered to attract particles and promote aggregation of the particles in the process of volatilizing a solvent of a coating liquid.
(Antiglare Film)
A ratio of the particles 5 to the matrix 2 in each of the antiglare films 30 and 40, the film thickness of each of the antiglare films 30 and 40, Ra of each of the surfaces 30s and 40s, and Rsm of each of the surfaces 30s and 40s are not particularly limited, and may be in the range described for the first and second embodiments.
In the antiglare films 30 and 40, the particles 5 are aggregated and locally stacked, and the height of the film is increased at this portion. Meanwhile, at another portion, the particles 5 are not stacked and the film is locally thin. Difference between the highest portion and the lowest portion of each of the antiglare films 30 and 40 as measured from the principal surface 10s of the transparent substrate 10, may be preferably greater than or equal to three times the average particle diameter of the particles 5, and more preferably greater than or equal to four times the average particle diameter thereof.
In the region 40b of the antiglare film 40, the particles are not stacked in the film thickness direction or particles themselves do not exist. In the latter case, the film 40 may be merely formed of the matrix 2 in the region 40b. A proportion of the region 40b in an area of a region in which the antiglare film 40 is formed may be, for example, preferably 5 to 90%, more preferably 10 to 70%, and particularly preferably 20 to 50%.
(Transparent Substrate)
The configuration of the transparent substrate 10 such as a preferable material and structure is as described above.
The antiglare films 30 and 40 may be each formed so as to cover the entirety of the principal surface 10s of the transparent substrate 10 or cover a part of the principal surface 10s. In the latter case, the antiglare films 30 and 40 may be each formed in at least a portion of the principal surface 10s which covers an image display surface of an image display apparatus.
(Optical Characteristics)
Gloss can be evaluated by specular glossiness. 60° specular glossiness of the transparent substrate 10 is, for example, preferably 60 to 130%, more preferably 70 to 120%, and particularly preferably 80 to 110% and 85 to 100%. The specular glossiness represents a value measured for the surface 10s on which the antiglare film 20 is formed. The haze ratio of the transparent substrate is, for example, preferably less than or equal to 20%, more preferably less than or equal to 15%, and particularly preferably less than or equal to 10%, and may be 1 to 8%, more preferably 1 to 6%, and particularly preferably 1 to 5% depending on cases.
The 60° specular glossiness G and the haze ratio H (%) preferably satisfy the relational expression (a) and more preferably satisfy the relational expression (b).
H≤−0.2 G+25 (a)
H≤−0.2 G+24.5 (b)
Japanese Industrial Standards Nos. to be referred to for measuring the gloss and the haze are as described above.
(Parameter about Material Ratio Curve)
The antiglare film-attached transparent substrates 200 and 300 can have the following characteristics concerning parameters about a material ratio curve according to ISO 25178. As defined in ISO 25178, the material ratio curve is represented by percentages obtained by accumulating frequencies at a certain height from the highest value with setting the total number of all pieces of the height data as 100. Based on the material ratio curve, a bearing area ratio at a certain height C is represented as Smr(C). Among straight lines in which difference between Smr values at two height points is 40%, a straight line having the smallest gradient is set as an equivalent line, and difference between the height at a bearing area ratio of 0% and the height at the bearing area ratio of 100% in the equivalent line is a level difference Sk of a core portion. Smr1 represents a bearing area ratio for distinguishing between the core portion and a protruding hill portion having a height greater than or equal to the height of the core portion. Meanwhile, Smr2 represents a bearing area ratio for distinguishing between the core portion and a protruding valley portion having a height less than or equal to the height of the core portion. The surface heights at the bearing area ratios of 20, 40, 60, 80% are represented as BH20, BH40, BH60, BH80, respectively.
Smr1 is preferably 1 to 40% and more preferably 3 to 35%, and may be 10 to 30% depending on cases. BH20 is, for example, preferably 0.04 μm to 0.5 μm, more preferably 0.06 μm to 0.5 μm, and even more preferably 0.12 μm to 0.3 μm. BH80 is, for example, preferably −0.3 μm to 0 μm, more preferably −0.3 μm to −0.05 μm, and even more preferably −0.25 μm to −0.12 μm.
The antiglare films 50 and 60 include first regions 50p and 60p and second regions 50v and 60v, respectively. In the first regions 50p and 60p, the particles 5 are stacked in the thickness direction of the antiglare films 50 and 60. According to observation of the antiglare films 50 and 60 from the surface side along the thickness direction, the second regions 50v and 60v surround the first regions 50p and 60p. However, the second regions 50v and 60v may be surrounded by the first regions 50p and 60p. The first regions 50p and 60p and the second regions 50v and 60v are, for example, disposed such that one of the first region 50p, 60p and the second region 50v, 60v is disposed between a plurality of the other regions spaced from each other. This structure may be referred to as a sea-island structure. The second regions 50v and 60v are valley-shaped regions having the surfaces retracted from the surrounding first regions. Therefore, in a case where the island portions are the first regions 50p and 60p, the island portion of the sea-island structure protrudes from the sea portion, and, in a case where the island portions are the second regions 50v and 60v, the island portion is depressed from the sea portion. In the second regions 50v and 60v, the number of the particles 5 stacked is small as compared with the first regions 50p and 60p. The second regions 50v and 60v may include a portion 50t in which the particles 5 are stacked (see
The “plateau-shaped” means that the upper portion of the protrusion of each of the antiglare films 50 and 60 appears to be plateau-shaped when the film is observed by an SEM or the like. Strictly speaking, the “plateau-shaped” means that L2/L1≥0.75, in particular, L2/L1≥0.8 is satisfied on the cross-section of the film. As shown in
Boundaries 50b and 60b between the first regions 50p and 60p and the second regions 50v and 60v can be determined by average thicknesses T of the antiglare films 50 and 60, respectively (see
The width Wp may be preferably greater than or equal to 5 μm, more preferably greater than or equal to 7.7 μm, and even more preferably greater than or equal to 10 μm. The width Wv may be greater than or equal to 3.5 μm, preferably greater than or equal to 7 μm, and more preferably greater than or equal to 10 μm. In a case where BR>B the width Wp is great, visible light incident on the antiglare film is likely to be directly transmitted, and the haze ratio thus tends to be small. In a case where the width Wv is great, visible light incident on the antiglare film is appropriately scattered, and gloss thus tends to be small. A film in which both the width Wp and the width Wv are greater than or equal to 10 μm is particularly suitable for achieving both a low haze ratio and low gloss.
The first regions 50p and 60p and the second regions 50v and 60v are, for example, each a region extending preferably over 0.25 μm2 or more, more preferably over 0.5 μm2 or more, and particularly preferably over 1 μm2 or more, and may be each a region extending preferably over 5 μm2 or more and more preferably over 10 μm2 or more depending on cases.
The antiglare films 50 and 60 include the first regions 50p and 60p and the second regions 50v and 60v. A proportion of each of the second regions 50v and 60v in an area of a region in which the antiglare film 40 is formed may be, for example, preferably 5 to 90%, more preferably 10 to 70%, and particularly preferably 20 to 50%. The antiglare films 50 and 60 may be merely formed of the first regions 50p and 60p and the second regions 50v and 60v, respectively.
(Particles)
The particles 5 are as described for the third embodiment.
(Matrix)
The matrix 2 is as described for the first to the third embodiments. However, the present embodiment is different from the third embodiment in that promotion of aggregation of the particles 5 through addition of nitrogen atoms is less required in the present embodiment. Therefore, metal oxide such as silicon oxide which forms the matrix 2 is preferably formed of a hydrolyzable organic metal compound, in particular, a compound represented by formula (1). The matrix 2 may be substantially formed of silicon oxide.
(Antiglare Film)
In the antiglare films 50 and 60, the ratio of the particles 5 to the matrix 2, the film thickness, Ra of each of surfaces 50s and 60s, and Rsm of each of the surfaces 50s and 60s are not particularly limited, and may be in the ranges described for the first and second embodiments. Difference between the highest portion and the lowest portion of each of the antiglare films 50 and 60 as measured from the principal surface 10s of the transparent substrate 10, may be preferably greater than or equal to three times the average particle diameter of the particles 5 and more preferably greater than or equal to four times the average particle diameter thereof.
(Transparent Substrate)
The configuration of the transparent substrate 10 such as a preferable material and structure is as described above.
(Optical Characteristics)
Gloss can be evaluated by specular glossiness. 60° specular glossiness of the transparent substrate 10 is, for example, preferably 60 to 130%, more preferably 70 to 120%, and particularly preferably 80 to 110% and 85 to 100%. The specular glossiness represents a value measured for the surface 10s on which the antiglare film 20 is formed. The haze ratio of the transparent substrate is, for example, preferably less than or equal to 20%, more preferably less than or equal to 15%, and particularly preferably less than or equal to 10%, and may be 1 to 8%, more preferably 1 to 6%, and particularly preferably 1 to 5% depending on cases.
The 60° specular glossiness G and the haze ratio H (%) preferably satisfy the relational expression (a), more preferably satisfy the relational expression (b), and even more preferably satisfy the relational expression (c). G and H may satisfy the relational expression (d).
H≤−0.2 G+25 (a)
H≤−0.2 G+24.5 (b)
H≤−0.2 G+24 (c)
H≤−0.15 G+18 (d)
Japanese Industrial Standards Nos. to be referred to for measuring the gloss and the haze are as described above.
In a glass container, 1 g of a smectite dispersion liquid (“LAPONITE” manufactured by BYK) and 120 g of a dispersing agent (liquid obtained by diluting “BYK-102” manufactured by BYK with industrial ethanol (P-7) to 0.15 wt %) were placed and prepared a particulate dispersion liquid with an ultrasonic washing machine. The flat-plate-shaped particles contained in the smectite dispersion liquid had an average diameter of 0.05 μm and an average thickness of 1 nm. The dispersion medium of the smectite dispersion liquid was water, and the content of the dispersoid was 1 wt %.
2.149 g of propylene glycol monomethyl ether, 0.537 g of propylene glycol, 0.05 g of purified water, 0.125 g of a nitric acid solution (liquid obtained by diluting 60 wt % of concentrated nitric acid with industrial ethanol (P-7) to 0.025 wt %), 0.139 g of tetraethoxysilane, and 1.5 g of the above-described dispersing agent were mixed and aging was performed at room temperature overnight to prepare a matrix precursor liquid. In the matrix precursor liquid, 40 g of the particulate dispersion liquid was mixed and prepared a coating liquid with an ultrasonic washing machine.
A glass sheet (100×100 mm float sheet glass; thickness of 3 mm) was immersed in an aqueous KOH solution having a pH of 13, washed with an ultrasonic washing machine, and dried. By a pipette, 3 g of the coating liquid was taken and applied to the principal surface of the glass sheet by a flow-coating method in which the liquid was caused to flow onto the principal surface of the glass sheet. Thereafter, the obtained product was dried in an oven set to 200° C. to obtain an antiglare film-attached transparent substrate.
When the antiglare film-attached transparent substrate was visually observed, no defects were confirmed on the outer appearance. The 60° gloss value measured from the side on which the antiglare film was formed, by using a gloss checker (“gloss checker IG-320” manufactured by HORIBA, Ltd.), was 100.9. The haze ratio measured by using a haze meter (“haze meter NDH-200” manufactured by NIPPON DENSHOKU INDUSTRIES CO., LTD.) was 6.2%. Furthermore, the arithmetic average roughness Ra of a roughness profile which was measured for the surface of the antiglare film by using a laser microscope was 40 nm, and the average length Rsm of the roughness profile elements was 15 μm.
1.707 g of propylene glycol monomethyl ether, 0.427 g of propylene glycol, 0.03 g of purified water, 0.3 g of a nitric acid solution (liquid obtained by diluting 60 wt % of concentrated nitric acid with industrial ethanol (AP-7) to 0.025 wt %), 0.417 g of tetraethoxysilane, and 0.12 g of a kaolin dispersion liquid (“kaolin TS90” manufactured by Imerys Minerals Japan K. K.) were mixed, and prepared a coating liquid with an ultrasonic washing machine. The average particle diameter of the flat-plate-shaped particles contained in the kaolin dispersion liquid was 0.2 μm, and the average thickness thereof was 1 nm. The dispersion medium of the kaolin dispersion liquid was industrial ethanol (P-7), and the content of the dispersoid was 10 wt %.
Subsequently, in the same manner as in Example 1, an antiglare film-attached transparent substrate was obtained. When the antiglare film-attached transparent substrate was visually observed, no defects were confirmed on the outer appearance. When the characteristics were measured in the same manner as in Example 1, the 60° gloss value was 92.6, the haze ratio was 4.1%, Ra was 60 nm, and Rsm was 25 μm.
By using a stirrer, 1.254 g of propylene glycol monomethyl ether, 0.45 g of propylene glycol, 0.225 g of industrial ethanol (P-7), 0.101 g of a nitric acid solution (liquid obtained by diluting 60 wt % of concentrated nitric acid with propylene glycol monomethyl ether to 1 wt %), 0.8 g of a colloidal silica dispersion liquid (liquid obtained by diluting “PGM-AC-4130Y” manufactured by Nissan Chemical Corporation with propylene glycol monomethyl ether to 10 wt %), 0.125 g of tetraethoxysilane, and 0.045 g of γ-aminopropyltrimethoxysilane (liquid obtained by diluting “KBM-903” manufactured by Shin-Etsu Chemical Co., Ltd. with propylene glycol monomethyl ether to 1 wt %) were mixed for three hours to prepare a coating liquid. The “PGM-AC-4130Y” contained spherical silica particles having an average particle diameter of 40 to 50 nm at a solid content concentration of 30 wt %, and the particles were not aggregated and were each individually dispersed.
In the same manner as in Example 1, an antiglare film-attached transparent substrate was obtained. When the antiglare film-attached transparent substrate was visually observed, no defects were visually confirmed on the outer appearance. When the characteristics were measured in the same manner as in Example 1, the 60° gloss value was 99.2, the haze ratio was 5.5%, Ra was 81 nm, and Rsm was 13.8 μm.
In Examples 4 to 7, antiglare film-attached transparent substrates were obtained in the same manner as in Example 3 except that, in a coating liquid, blending amounts of the nitric acid solution, the colloidal silica dispersion liquid, tetraethoxysilane (TEOS), and γ-aminopropyltrimethoxysilane (aminosilane) were as indicated in Table 1. When the antiglare film-attached transparent substrates were visually observed, no defects were visually confirmed on the outer appearance. When the characteristics were measured in the same manner as in Example 1, the 60° gloss values were 99.0, 98.2, 110.4, 86.6, the haze ratios (%) were 4.3, 7.1, 4.4, 7.1, Ra (nm) was 92, 80, 92, 89, and Rsm (μm) was 9.8, 12.0, 17.0, 13.2 in Examples 4 to 7, respectively. Table 2 indicates the results with the measured values in Examples 1 to 3.
Next, a parameter about a material ratio curve according to ISO 25178 was examined. A material ratio curve was calculated based on the height data obtained in an observed visual field by a laser microscope (“LMeye7” manufactured by Lasertec Corporation), and, based on the material ratio curve, the level difference Sk of a core portion in the height direction, a bearing area ratio Smr1 for distinguishing between the core portion and the protruding hill portion, a bearing area ratio Smr2 for distinguishing between the core portion and the protruding valley portion, and the surface heights BH20, BH40, BH60, BH80 at the bearing area ratios of 20, 40, 60, 80%, respectively, were obtained. Table 3 indicates the results.
In Examples 2, 4, and 7, the 60° specular glossiness G and the haze ratio H (%) satisfied H≤−0.2 G+24.5.
Furthermore, when analysis was performed by using an SEM photograph, it was confirmed that, in Examples 1 and 2, the principal surfaces of the flat-plate-shaped particles were substantially parallel to the principal surface of the glass sheet. When the crystal planes of smectite and kaolin oriented along the principal surface of the transparent substrate were confirmed by X-ray diffraction analysis for the antiglare film-attached transparent substrates of Examples 1 and 2, it was confirmed that the crystal planes of both smectite and kaolin were (001) planes.
By using a stirrer, 1.960 g of industrial ethanol (P-7), 0.266 g of a liquid obtained by diluting purified water with the above-described P-7 to 10 wt %, 0.101 g of a nitric acid solution (liquid obtained by diluting 60 wt % of concentrated nitric acid with the above-described P-7 to 1 wt %), 0.150 g of a colloidal silica dispersion liquid (“MEK-ST-L” manufactured by Nissan Chemical Corporation), and 0.156 g of tetraethoxysilane were mixed for three hours, to prepare a coating liquid. The “MEK-ST-L” contained spherical silica particles having the average particle diameter of 40 to 50 nm at a solid content concentration of 30 wt %, and the particles were not aggregated and were each individually dispersed, and the dispersion medium was methyl ethyl ketone.
Subsequently, in the same manner as in Example 1, an antiglare film-attached transparent substrate was obtained. When the antiglare film-attached transparent substrate was visually observed, no defects were visually confirmed on the outer appearance. When the characteristics were measured in the same manner as in Example 1, the 60° gloss value was 82.8, and the haze ratio was 4.1%.
The film surface was observed by a microscope with use of the above-described laser microscope. Thus, three-dimensional image data, including height data, of the shape of the film surface was obtained. At this time, the optical magnification was set to 50× magnification. The visual field range of the obtained image corresponded to a 300 μm×300 μm square shape, and the resolution was 1024 pixels×1024 pixels.
From the three-dimensional image data, the width of the first region (plateau-shaped region) and the width of the second region (valley-shaped region) were obtained as follows. An evaluation target line for evaluating the height data was determined, and the plateau-shaped regions and the valley-shaped regions were determined at the evaluation target line while the image data was observed, and the width of each plateau-shaped region and the width of each valley-shaped region were measured. In a case where the plateau-shaped region and the valley-shaped region were not able to be distinguished from each other through the observation of the image data, the cross-sectional height profile at the evaluation target line was obtained, and a portion higher than the reference line was determined as the plateau-shaped region, and a portion lower than the reference line was determined as the valley-shaped region, and the lengths thereof were measured. The reference line was set so as to have an arithmetic average height of the height data in at least ¼ of the range, in the length direction, of the cross-sectional height profile. The average thickness T (see
By using a stirrer, 2.319 g of industrial ethanol (P-7), 0.158 g of a liquid obtained by diluting purified water with the above-described P-7 to 10 wt %, 0.101 g of a nitric acid solution (liquid obtained by diluting 60 wt % of concentrated nitric acid with the above-described P-7 to 1 wt %), 0.090 g of a colloidal silica dispersion liquid (“MEK-ST-L” manufactured by Nissan Chemical Corporation), and 0.094 g of tetraethoxysilane were mixed for three hours, to prepare a coating liquid.
Subsequently, in the same manner as in Example 1, an antiglare film-attached transparent substrate was obtained. When the antiglare film-attached transparent substrate was visually observed, no defects were visually confirmed on the outer appearance. When the characteristics were measured in the same manner as in Example 1, the 60° gloss value was 94.1, and the haze ratio was 4.7%. The width Wp of the first region and the width Wv of the second region were obtained in the same manner as in Example 8. As a result, Wp was 9.6 μm and Wv was 20.3 μm.
By using a stirrer, 1.776 g of propylene glycol monomethyl ether, 0.45 g of propylene glycol, 0.101 g of a nitric acid solution (liquid obtained by diluting 60 wt % of concentrated nitric acid with propylene glycol monomethyl ether to 1 wt %), 0.150 g of a colloidal silica dispersion liquid (“MEK-ST-L” manufactured by Nissan Chemical Corporation), and 0.150 g of tetraethoxysilane were mixed for three hours, to prepare a coating liquid.
Subsequently, in the same manner as in Example 1, an antiglare film-attached transparent substrate was obtained. When the antiglare film-attached transparent substrate was visually observed, no defects were visually confirmed on the outer appearance. When the characteristics were measured in the same manner as in Example 1, the 60° gloss value was 98.4 and the haze ratio was 4.9%. The width Wp of the first region and the width Wv of the second region were obtained in the same manner as in Example 8. As a result, Wp was 6.8 μm and Wv was 4.8 μm.
By using a stirrer, 1.776 g of propylene glycol monomethyl ether, 0.45 g of propylene glycol, 0.225 g of industrial ethanol (P-7), 0.127 g of a nitric acid solution (liquid obtained by diluting 60 wt % of concentrated nitric acid with propylene glycol monomethyl ether to 1 wt %), 0.800 g of a colloidal silica dispersion liquid (liquid obtained by diluting “PGM-AC-4130Y” manufactured by Nissan Chemical Corporation with propylene glycol monomethyl ether to 10 wt %), and 0.125 g of tetraethoxysilane were mixed for three hours, to prepare a coating liquid.
Subsequently, in the same manner as in Example 1, an antiglare film-attached transparent substrate was obtained. When the antiglare film-attached transparent substrate was visually observed, no defects were visually confirmed on the outer appearance. When the characteristics were measured in the same manner as in Example 1, the 60° gloss value was 106.6 and the haze ratio was 4.4%. The width Wp of the first region and the width Wv of the second region were obtained in the same manner as in Example 8. As a result, Wp was 5.0 μm and Wv was 1.7 μm.
Table 4 collectively indicates the results of Examples 8 to 11.
In Examples 8, 9, the 60° specular glossiness G and the haze ratio H (%) satisfied H≤−0.2 G+24. In Example 8, the relationship of H≤−0.15 G+18 was also satisfied.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-045862 | Mar 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/010462 | 3/15/2021 | WO |
