JP2007057372A - Abrasion resistant capacity evaluating method of surface film and surface film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubbing resistant capacity inspection method of a surface film which accurately and quantitatively inspects the rubbing resistant capacity of the surface film. <P>SOLUTION: An antireflection film is rubbed using a rubbing tester according to an eraser rubbing method and a steel wool method to form a sample. Fluorescent lamps 12 and 13 are lighted to photograph the sample 6 set on a sample stand 5 so as to contain a rubbing part (S11). A PC 20 is constituted so as to perform brightness density converting software to convert the brightness of the photographed image to density (S12). The quantitative value of the average density difference between a rubbed bright part and a non-rubbed non-bright part is calculated on the basis of the converted density (S13). A range not leaving a rubbing mark, that is, causing no practical problem is preliminarily calculated and the rubbing resistant capacity of the antireflection film is evaluated depending upon whether the calculated quantitative value is present within the resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for evaluating the scratch resistance of a surface film for evaluating the scratch resistance of a surface film attached to the surface of a flat panel display.

  Conventionally, JIS K5400 (5600) and JIS K7204 each show a pencil scratch test method and a taper wear test method as methods for inspecting the scratch resistance performance of a surface film attached to the surface of a flat panel display. The scratch resistance of the surface film is an index indicating how much performance can be maintained against scratches.

  In addition, with respect to the scratch resistance test using an eraser or steel wool, examples of applying to a paint film or a spectacle lens as an abrasion durability test are known. Further, in a cathode ray tube TV, as a de facto standard, it is known to perform a wear test using a plastic eraser.

However, the conventional method has not been reported as an example applied to a surface film attached to the surface of a flat panel display such as a thin TV.
Conventionally, evaluation of the scratch resistance performance of a surface film to be attached to the surface of a flat panel display has been performed visually with the human eye (unaid eye), and has no quantitativeness. Furthermore, there was no specific provision regarding the scratch resistance performance of the surface film for flat panel displays.

  Accordingly, an object of the present invention is to provide a method capable of quantitatively evaluating the scratch resistance performance of a surface film.

  The scratch resistance evaluation method for a surface film of the present invention is a scratch resistance evaluation method for a surface film for evaluating the scratch resistance performance of a surface film attached to the surface of a flat panel display. A rubbing step for rubbing the film; a reflected light detecting step for detecting a first reflected light from the rubbed portion of the surface film; and a second reflected light from the non-rubbed portion; A density calculating step for obtaining a first density according to the light quantity of the first reflected light and a second density according to the light quantity of the second reflected light; and a difference between the first density and the second density And evaluating the scratch resistance performance based on

  In the scratch resistance evaluation method for a surface film of the present invention, the surface film is rubbed with an eraser in the rubbing step.

  In the scratch resistance evaluation method for a surface film of the present invention, the surface film is rubbed with steel wool in the rubbing step.

  The scratch resistance evaluation method for a surface film of the present invention specifies the number of rubbing times of the surface film and the load applied to the surface film as the predetermined condition.

  In the scratch resistance evaluation method for a surface film of the present invention, the surface film is an antireflection film.

  The surface film of the present invention is a surface film attached to the surface of a flat panel display, and as a result of executing the scratch resistance evaluation method, the difference between the first concentration and the second concentration is 0.1. It is as follows.

  In the surface film of the present invention, the surface film includes an antireflection film.

  According to the present invention, it is possible to provide a method capable of quantitatively evaluating the scratch resistance performance of a surface film.

  Hereinafter, a method for evaluating the scratch resistance performance of a surface film attached to the surface of a flat panel display, which is an embodiment of the present invention, will be described.

FIG. 1 is a diagram showing a flow of a method for evaluating scratch resistance of a surface film for explaining an embodiment of the present invention.
In this evaluation method, first, a test is performed on the surface film to prepare a sample (S1). Based on the prepared sample, an evaluation value for quantitatively evaluating the scratch resistance performance of the surface film is calculated (S2). Finally, the scratch resistance performance of the surface film is evaluated based on the calculated evaluation value (S3). Hereinafter, each of these steps will be described in detail.

(S1: Preparation of sample)
As a test method in S1, in this embodiment, a sample is prepared using the eraser rubbing method shown in the following (a) and the steel wool method shown in (b). The surface film to be tested is, for example, an antireflection film. As will be described later, the antireflection film is obtained by laminating a hard coat layer and a low refractive index layer in this order on a transparent support.

(A) Eraser rubbing method In the eraser rubbing method, a rubbing tester is used to rub the surface of the antireflection film under the following rubbing conditions, for example. The surface of the antireflection film is a surface exposed when the antireflection film is attached to a flat panel display, and here refers to the surface on the low refractive index layer side.
Environmental conditions: 25 ° C, 55% RH
Rubbing member for rubbing the antireflection film: Plastic eraser (trade name MONO, manufactured by Dragonfly Pencil Co., Ltd.)
Contact area of the tip of the rubbing member to be brought into contact with the sample: 1 cm × 1 cm
Movement distance of rubbing member on sample (one way): 3cm
Rubbing speed of rubbing member: 32 mm / sec Load applied to tip of rubbing member: 500 g / cm ²
Number of rubbing of rubbing member: 1 to 500 reciprocations (preferably 200 reciprocations)
Black PET is attached to the back side of the antireflection film that has been rubbed with the rubbing member under the above conditions to complete the preparation of the sample.

(B) Steel Wool Method In the steel wool method, a rubbing tester is used, and the surface of the antireflection film is rubbed, for example, under the following rubbing conditions.
Environmental conditions: 25 ° C, 55% RH
Rub member: Steel wool (manufactured by Nippon Steel Wool Co., Ltd., Grade No. 0000)
Contact area of the tip of the rubbing member to be brought into contact with the sample: 1 cm × 1 cm
Movement distance of rubbing member on sample (one way): 13 cm
Rubbing speed of rubbing member: 13 cm / sec Load applied to tip of rubbing member: 500 g / cm ² (preferably 200 g / cm ² )
Number of rubbing of the rubbing member: 1 to 50 reciprocations (preferably 10 reciprocations)
Black PET is attached to the back surface of the antireflection film that has been rubbed with the rubbing member under the above conditions, and the preparation of the sample is completed.

  On the surface of the antireflection film of the sample obtained in this step, there are a rubbed portion rubbed by the rubbing member and a non-rubbed portion that is not rubbed.

(S2: Evaluation value calculation)
FIG. 2 is a diagram showing a schematic configuration of an evaluation value calculation system for calculating an evaluation value for quantitatively evaluating the scratch resistance performance of the surface film.
The evaluation value calculation system shown in FIG. 2 includes a sample stage 5 on which the sample 6 is placed, and a light detection device that detects reflected light from the sample 6 placed on the sample stage 5 with the antireflection film facing up. 11, two fluorescent lamps 12 and 13 for illuminating the sample 6, and a computer 20 connected to the light detection device 11.

  The fluorescent lamps 12 and 13 are arranged symmetrically about the sample stage 5 so that light is incident on the rubbing part and the non-rubbed part of the sample 6 placed on the sample stage 5 under the same conditions. Further, the height of the fluorescent lamps 12 and 13 can be adjusted within a range of 2 to 30 cm, for example, depending on how the rubbing portion of the sample 6 placed on the sample stage 5 is seen. Since the rubbing part is shining, it is desirable to install the fluorescent lamps 12 and 13 so that this shine can be seen well.

  The light detection device 11 includes first reflected light that is light from the fluorescent lamps 12 and 13 reflected by the rubbing portion, and second reflected light that is light from the fluorescent lamps 12 and 13 reflected by the non-rubbed portion. It has a function to detect. As the light detection device 11, for example, a digital camera can be used.

  The computer 20 obtains a density value corresponding to the light quantity of the first reflected light detected by the light detection device 11 and a density value corresponding to the light quantity of the second reflected light, and based on these density values, the reflection is performed. The evaluation value of the prevention film is calculated.

FIG. 3 is a diagram showing a flow when calculating an evaluation value using the evaluation value calculation system shown in FIG. Here, the light detection device 11 will be described as a digital camera.
The fluorescent lamps 12 and 13 are turned on with the sample 6 placed on the sample stage 5, and the digital camera 11 captures an area including at least the rubbing portion and the non-rubbing portion of the sample 6 (S11). Image data obtained by photographing is automatically transferred to the computer 20 via, for example, IEEE1394. The computer 20 executes software for converting the luminance value of the image data into a density value, and converts the luminance value of the image data obtained by photographing into a density value (S12). The converted density value is a value corresponding to the amount of light detected by the photoelectric conversion element included in the imaging element of the digital camera 11. Based on the converted density value, the computer 20 obtains the average density of the density according to the light quantity of the first reflected light and the average density of the density according to the light quantity of the second reflected light, and the difference between them. Is calculated as an evaluation value (S13).

  Here, although the difference between the average densities is used as the evaluation value, the density corresponding to the light detected by one photoelectric conversion element of the image sensor of the digital camera 11 in the first reflected light, and the second The difference between the reflected light and the density according to the light detected by one photoelectric conversion element of the imaging element may be used as the evaluation value. By using the difference between the average densities as the evaluation value, more accurate evaluation can be performed.

(S3: Evaluation based on evaluation value)
The evaluation of the scratch resistance performance of the surface film is performed using the evaluation value calculated in step S13. That is, when this evaluation value is large, it means that the performance of the surface film (antireflection performance in the case of an antireflection film) is greatly changed between the rubbing portion and the non-rubbing portion, so that the scratch resistance performance is poor. Can be evaluated. On the other hand, when this evaluation value is small, it means that the performance does not change much between the rubbing portion and the non-rubbing portion, and therefore it can be evaluated that the scratch resistance performance is good.

  Alternatively, a certain reference value may be set as the evaluation value, and the scratch resistance performance may be evaluated based on the number of abrasions of the eraser or steel wool until the reference value is reached.

  The evaluation value is greatly affected by the number of rubbing and the load among the rubbing conditions. For example, the evaluation value increases as the number of rubbing times and the load increases, and the evaluation value decreases as the number of rubbing times and the load decreases. If the number of rubbing is too small or the value of the load is too small, almost the same value is obtained for any surface film, and accurate evaluation is difficult. For this reason, it is necessary to determine the rubbing conditions (particularly, the number of rubbing and the load) so that the difference in evaluation value is clearly obtained in any surface film.

  The antireflection film that is the surface film of the flat panel display has an evaluation value of 0 when the antireflection film is rubbed by the eraser rubbing method (the rubbing conditions are the above-mentioned conditions, but the number of rubbing is 200 reciprocations). If it is 0.5 or more and more preferably 0 or more and 0.1 or less, it can be used practically without any problem. The evaluation value when the antireflection film is rubbed by the steel wool method (the rubbing condition is as described above, but the number of rubbing is 10 reciprocations) is 0 or more and 0.5 or less, more preferably 0 or more. If it is 0.1 or less, it can be used practically without problems.

Hereinafter, the antireflection film as an example of the surface film will be described.
In general, the antireflection film has a structure in which at least one functional layer and a low refractive index layer are laminated on a transparent support. The functional layer may be either an optical functional layer or a physical functional layer, and examples of the optical functional layer include a high refractive index layer and a light diffusion layer. Examples of the physical function layer include a hard coat layer and an antistatic layer. An optical functional layer and a physical functional layer may be used, and examples thereof include an antiglare hard coat layer. The antireflection film of the present embodiment has a structure in which an antiglare hard coat layer is further laminated on a transparent support, and a low refractive index layer is further laminated thereon.

(Anti-glare hard coat layer)
The antiglare hard coat layer contains a binder for imparting hard coat properties and matte particles for imparting antiglare properties, and preferably for increasing the refractive index, preventing crosslinking shrinkage, and increasing the strength. Contains an inorganic filler.

(Anti-glare hard coat layer binder)
The binder of the antiglare hard coat layer is preferably a polymer having a saturated hydrocarbon chain or a polyether chain as the main chain, and more preferably a polymer having a saturated hydrocarbon chain as the main chain. The binder polymer of these antiglare hard coat layers preferably has a reactive crosslinking group.

  As the binder polymer having a saturated hydrocarbon chain as a main chain, a polymer of an ethylenically unsaturated monomer (binder precursor) is preferable. As the binder polymer having a saturated hydrocarbon chain as a main chain and having a reactive crosslinking group, a (co) polymer of monomers having two or more ethylenically unsaturated groups is preferable.

  Examples of the monomer having two or more ethylenically unsaturated groups include esters of polyhydric alcohol and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol tetra ( (Meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its derivatives Examples include 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide) and methacrylamide. Can be mentioned. Two or more of these monomers may be used in combination.

Polymerization of these monomers having an ethylenically unsaturated group can be carried out by irradiation with ionizing radiation or heating in the presence of a photo radical initiator or a thermal radical initiator.
Accordingly, a coating liquid containing a monomer having an ethylenically unsaturated group, a photo radical initiator or a thermal radical initiator, mat particles such as inorganic fine particles is prepared, and the coating liquid is applied on a transparent support, and then ionizing radiation is used. Or it hardens | cures by the polymerization reaction by a heat | fever and forms an anti-glare hard-coat layer.

  As radical photopolymerization initiators, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds And fluoroamine compounds and aromatic sulfoniums. Examples of acetophenones include 2,2-diethoxyacetophenone, p-dimethylacetophenone, 1-hydroxydimethylphenyl ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-4-methylthio-2-morpholinopropiophenone and 2 -Benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone is included. Examples of benzoins include benzoin benzene sulfonate, benzoin toluene sulfonate, benzoin methyl ether, benzoin ethyl ether and benzoin isopropyl ether. Examples of the benzophenones include benzophenone, 2,4-dichlorobenzophenone, 4,4-dichlorobenzophenone and p-chlorobenzophenone. Examples of phosphine oxides include 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

Various examples are described in the latest UV curing technology (P.159, issuer; Kazuhiro Takasagi, publisher; Technical Information Association, Inc., published in 1991), which is useful for this embodiment.
Preferable examples of commercially available photocleavable photoradical polymerization initiators include Irgacure (651, 184, 907) manufactured by Ciba Specialty Chemicals. Further, as described in JP-A-6-41468, it is also preferably used in combination of two photopolymerization initiators.
It is preferable to use a photoinitiator in the range of 0.1-15 mass parts with respect to 100 mass parts of polyfunctional monomers, More preferably, it is the range of 1-10 mass parts. In addition to the photopolymerization initiator, a photosensitizer may be used. Specific examples of the photosensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, Michler's ketone and thioxanthone.

  As the thermal radical initiator, organic or inorganic peroxides, organic azo, diazo compounds, and the like can be used. Specifically, benzoyl peroxide, halogen benzoyl peroxide, lauroyl peroxide, acetyl peroxide, dibutyl peroxide, cumene hydroperoxide, butyl hydroperoxide as organic peroxides, hydrogen peroxide, peroxides as inorganic peroxides. Ammonium sulfate, potassium persulfate, etc., 2-azo-bis-isobutyronitrile, 2-azo-bis-propionitrile, 2-azo-bis-cyclohexanedinitrile, etc. as diazo compounds, diazoaminobenzene, p-nitrobenzenediazonium Etc.

The polymer having a polyether as the main chain is preferably a ring-opening polymer of a polyfunctional epoxy compound. The ring-opening polymerization of the polyfunctional epoxy compound can be performed by irradiation with ionizing radiation or heating in the presence of a photoacid generator or a thermal acid generator.
Accordingly, a coating liquid containing a polyfunctional epoxy compound, a photoacid generator or a thermal acid generator, matte particles, preferably further containing an inorganic filler is prepared, and the coating liquid is applied on a transparent support, and then ionizing radiation or heat is applied. It cures by the polymerization reaction by and forms a low refractive index layer.

Instead of or in addition to a monomer having two or more ethylenically unsaturated groups, a monomer having a crosslinkable functional group is used to introduce a crosslinkable functional group into the polymer, and by reaction of this crosslinkable functional group, A crosslinked structure may be introduced into the binder polymer.
Examples of the crosslinkable functional group include isocyanate group, epoxy group, aziridine group, oxazoline group, aldehyde group, carbonyl group, hydrazine group, carboxyl group, methylol group and active methylene group. Vinylsulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, and metal alkoxide such as tetramethoxysilane can also be used as a monomer for introducing a crosslinked structure. A functional group that exhibits crosslinkability as a result of the decomposition reaction, such as a block isocyanate group, may be used. That is, in this embodiment, the crosslinkable functional group may not react immediately but may exhibit reactivity as a result of decomposition.
These binder polymers having a crosslinkable functional group can form a crosslinked structure by heating after coating.

In addition, in order to obtain a high refractive index, the structure of the ethylenically unsaturated monomer contains at least one atom selected from an aromatic ring, a halogen atom other than fluorine, a sulfur atom, a phosphorus atom, and a nitrogen atom. Is preferred.
Specific examples of the high refractive index monomer include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like. Two or more of these monomers may be used in combination.

  The binder of the antiglare hard coat layer is added in an amount of 20 to 95% by mass based on the solid content of the coating composition of the layer.

(Matte particles)
For the purpose of imparting antiglare properties, the antiglare hard coat layer is a matte particle having an average particle size of 1 to 10 μm, preferably 1.5 to 7.0 μm, such as inorganic compound particles or resin, for the purpose of imparting antiglare properties. Contains particles.
As specific examples of the mat particles, inorganic particles such as silica particles and TiO ₂ particles; resin particles such as acrylic particles, crosslinked acrylic particles, polystyrene particles, crosslinked styrene particles, melamine resin particles, and benzoguanamine resin particles are preferable. Can be mentioned. Of these, crosslinked styrene particles, crosslinked acrylic particles, and silica particles are preferred.
As the shape of the mat particle, either a true sphere or an indefinite shape can be used.

  Further, two or more kinds of mat particles having different particle diameters may be used in combination. It is possible to impart anti-glare properties with mat particles having a larger particle size and to impart other optical characteristics with mat particles having a smaller particle size. For example, when an antireflection film is attached to a high-definition display of 133 ppi or higher, it is required that there is no problem in optical performance called glare. Glare originates from the fact that the pixels are enlarged or reduced due to unevenness existing on the film surface (contributing to anti-glare properties) and lose uniformity of brightness, but with a particle size smaller than that of mat particles that provide anti-glare properties. It can be greatly improved by using mat particles having a different refractive index from the binder.

  Furthermore, the particle size distribution of the mat particles is most preferably monodisperse, and the particle sizes of the particles are preferably closer to each other. For example, when particles having a particle size of 20% or more than the average particle size are defined as coarse particles, the proportion of coarse particles is preferably 1% or less of the total number of particles, more preferably 0.1%. Or less, more preferably 0.01% or less. Matt particles having such a particle size distribution are obtained by classification after a normal synthesis reaction, and a matting agent having a more preferable distribution can be obtained by increasing the number of classifications or increasing the degree of classification.

The mat particles are contained in the antiglare hard coat layer so that the amount of the mat particles in the formed antiglare hard coat layer is preferably 10 to 2000 mg / m ² , more preferably 100 to 1400 mg / m ^2. Is done.
The particle size distribution of the mat particles is measured by a Coulter counter method, and the measured distribution is converted into a particle number distribution.

(Inorganic filler)
In order to increase the refractive index of the antiglare hard coat layer, in addition to the above mat particles, at least one metal selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony is used. It is preferable to contain an inorganic filler made of an oxide and having an average particle size of 0.2 μm or less, preferably 0.1 μm or less, more preferably 0.06 μm or less.
Conversely, in order to increase the difference in refractive index from the matte particles, an anti-glare hard coat layer using high-refractive index matte particles uses silicon oxide to keep the refractive index of the layer low. Is also preferable. The preferred particle size is the same as that of the aforementioned inorganic filler.
Specific examples of the inorganic filler for use in the antiglare hard coat _{layer, TiO 2, ZrO 2, Al} 2 O 3, In 2 O 3, ZnO, SnO 2, Sb 2 O 3, ITO and SiO ₂ or the like can be mentioned It is done. TiO ₂ and ZrO ₂ are particularly preferable from the viewpoint of increasing the refractive index. The surface of the inorganic filler is preferably subjected to a silane coupling treatment or a titanium coupling treatment, and a surface treatment agent having a functional group capable of reacting with a binder species on the filler surface is preferably used.
The added amount of these inorganic fillers is preferably 10 to 90% by mass, more preferably 20 to 80% by mass, and particularly preferably 30 to 75% by mass with respect to the total mass of the antiglare hard coat layer. is there.
Such a filler does not scatter because the particle size is sufficiently smaller than the wavelength of light, and a dispersion in which the filler is dispersed in a binder polymer behaves as an optically uniform substance.

  The refractive index of the portion excluding the matte particles of the antiglare hard coat layer is preferably 1.50 to 2.00, more preferably 1.50 to 1.80. In order to make the refractive index within the above range, the kind and amount ratio of the binder and the inorganic filler may be appropriately selected.

  The film thickness of the antiglare hard coat layer is preferably 1 to 10 μm, and more preferably 1.2 to 8 μm.

(Low refractive index layer)
Next, the low refractive index layer will be described below.
The low refractive index layer is formed by applying a coating liquid containing a binder and inorganic fine particles on the functional layer and curing. The refractive index of the low refractive index layer of the antireflection film of this embodiment is 1.20 to 1.49, preferably 1.30 to 1.44.

(Inorganic fine particles)
The low refractive index layer preferably contains inorganic fine particles having a hollow structure as inorganic fine particles in order to reduce the increase in refractive index.
As such hollow inorganic fine particles, silica having a hollow structure is preferable. The hollow silica fine particles preferably have a refractive index of 1.17 to 1.40, more preferably 1.17 to 1.35, and most preferably 1.17 to 1.30. The refractive index here represents the refractive index of the entire particle, and does not represent the refractive index of only the outer shell silica forming the hollow silica particles. At this time, if the radius of the cavity in the particle is a and the radius of the particle outer shell is b, the porosity x calculated from the following formula (III) is preferably 10 to 60%, more preferably 20 to 60. %, Most preferably 30-60%.
(Formula ^{III): x = (4πa 3} /3) / (4πb 3/3) × 100
If the hollow silica particles are made to have a lower refractive index and a higher porosity, the thickness of the outer shell becomes thinner and the strength of the particles becomes weaker. From the viewpoint of scratch resistance, the low refractive index is less than 1.17. Rate particles are not used.
The refractive index of these hollow silica particles was measured with an Abbe refractometer (manufactured by Atago Co., Ltd.).
Moreover, the manufacturing method of hollow silica is described, for example in Unexamined-Japanese-Patent No. 2001-233611 and 2002-79616.

The amount of the hollow silica is preferably from ^{1mg / m 2 ~100mg / m 2} , more preferably ^{5mg / m 2 ~80mg / m 2} , more preferably from ^{10mg / m 2 ~60mg / m 2} . When the blending amount is in the above range, the scratch resistance is excellent, the fine unevenness is reduced on the surface of the low refractive index layer, and the appearance such as black tightening and the integrating sphere reflectance are improved.
The average particle diameter of the hollow silica is preferably 30% to 150% of the thickness of the low refractive index layer, more preferably 35% to 80%, and still more preferably 40% to 60%. That is, if the thickness of the low refractive index layer is 100 nm, the particle size of the hollow silica is preferably 30 nm to 150 nm, more preferably 35 nm to 80 nm, and still more preferably 40 nm to 60 nm.
When the particle size of the silica fine particles is in the above range, the refractive index is lowered, fine irregularities are reduced on the surface of the low refractive index layer, and the appearance such as black tightening and the integrating sphere reflectance are improved. The silica fine particles may be either crystalline or amorphous, and monodisperse particles are preferred. The shape is most preferably a spherical diameter, but there is no problem even if the shape is indefinite.
Here, the average particle diameter of the hollow silica can be determined from an electron micrograph.

In the present embodiment, silica particles having no voids can be used in combination with hollow silica or alone. The preferred particle size of silica without voids is 30 nm to 150 nm, more preferably 35 nm to 80 nm, and most preferably 40 nm to 60 nm.
Further, at least one kind of silica fine particles having an average particle size of less than 25% of the thickness of the low refractive index layer (referred to as “small size particle size silica particles”) is used as silica fine particles having the above particle size (“large size particles”). It is preferably used in combination with “silica fine particles having a diameter”.
Since the fine silica particles having a small particle size can exist in the gaps between the fine silica particles having a large particle size, they can contribute as a retaining agent for the fine silica particles having a large particle size.
The average particle size of the silica fine particles having a small size is preferably 1 nm to 20 nm, more preferably 5 nm to 15 nm, and particularly preferably 10 nm to 15 nm. Use of such silica fine particles is preferable in terms of raw material costs and a retaining agent effect.

Silica fine particles are treated by physical surface treatment such as plasma discharge treatment or corona discharge treatment in order to stabilize dispersion in the dispersion or coating solution, or to improve the affinity and binding to the binder component. Chemical surface treatment with a surfactant, a coupling agent, or the like may be performed. The use of a coupling agent is particularly preferred. As the coupling agent, an alkoxy metal compound (eg, titanium coupling agent, silane coupling agent) is preferably used. Among these, treatment with a silane coupling agent having an acryloyl group or a methacryloyl group is particularly effective.
The above coupling agent is used as a surface treatment agent for the inorganic filler of the low refractive index layer in advance for surface treatment prior to the preparation of the layer coating solution, and is added as an additive during the preparation of the layer coating solution. It is preferable to make it contain in a layer.
The silica fine particles are preferably dispersed in the medium in advance before the surface treatment in order to reduce the load of the surface treatment.

As the binder in the low refractive index layer, the same binder as that used in the antiglare hard coat layer can be used.
In this embodiment, the hydrolyzate and partial condensate of the organosilane compound present in the functional layer that is the lower layer of the low refractive index layer are present, and the binder in the low refractive index layer is the hydrolyzate of the organosilane compound. It preferably has a functional group capable of crosslinking with the group represented by R ¹ in the general formula (1) of the partial condensate.

Examples of such a functional group include a (meth) acryloyl group if the group represented by R ¹ in the general formula (1) is a (meth) acryloyl group, and a hydroxy group if the group is an epoxy group. It is done.

Further, the binder having a low refractive index may be a fluorine-containing polymer. The fluoropolymer is preferably a fluoropolymer that is crosslinked by heat or ionizing radiation having a coefficient of dynamic friction of 0.03 to 0.15 and a contact angle with water of 90 to 120 °.
Examples of the fluorine-containing polymer used in the low refractive index layer include hydrolysis and dehydration condensate of perfluoroalkyl group-containing silane compounds (for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane). And a fluorine-containing copolymer having a fluorine-containing monomer unit and a structural unit for imparting crosslinking reactivity as structural components.

  Specific examples of the fluorine-containing monomer unit include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole. Etc.), a part of (meth) acrylic acid or a fully fluorinated alkyl ester derivative (for example, Biscoat 6FM [manufactured by Osaka Organic Chemical Co., Ltd.] or M-2020 [manufactured by Daikin]), a fully or partially fluorinated vinyl ether, etc. Of these, perfluoroolefins are preferred, and hexafluoropropylene is particularly preferred from the viewpoints of refractive index, solubility, transparency, availability, and the like.

  As structural units for imparting crosslinking reactivity, structural units obtained by polymerization of monomers having a self-crosslinkable functional group in advance in the molecule such as glycidyl (meth) acrylate and glycidyl vinyl ether, carboxyl groups, hydroxy groups, amino groups , Obtained by polymerization of a monomer having a sulfo group or the like (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, crotonic acid, etc.) And a structural unit obtained by introducing a crosslinking reactive group such as a (meth) acryloyl group into these structural units by a polymer reaction (for example, it can be introduced by a technique such as allowing acrylic acid chloride to act on a hydroxy group) And the like.

  In addition to the above-mentioned fluorine-containing monomer units and structural units for imparting crosslinking reactivity, monomers not containing fluorine atoms can be copolymerized as appropriate from the viewpoints of solubility in solvents and film transparency. The monomer unit that can be used in combination is not particularly limited. For example, olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, methyl acrylate, ethyl acrylate, acrylic acid- 2-ethylhexyl), methacrylates (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers ( Methyl vinyl ether, ethyl vinyl ether, cyclohexyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate etc.), acrylamides (N-tert-butylacrylamide, N Cyclohexyl acrylamide), methacrylamides, and acrylonitrile derivatives.

  As described in JP-A-10-25388 and JP-A-10-147739, a curing agent may be appropriately used in combination with the above polymer.

  The fluorine-containing polymer particularly useful in this embodiment is a random copolymer of perfluoroolefin and vinyl ethers or vinyl esters. In particular, it preferably has a group capable of undergoing a crosslinking reaction alone (a radical reactive group such as a (meth) acryloyl group, a ring-opening polymerizable group such as an epoxy group or an oxetanyl group). These cross-linking reactive group-containing polymer units preferably occupy 5 to 70 mol%, particularly preferably 30 to 60 mol% of the total polymer units of the polymer.

  As a preferred form of the fluorinated copolymer, there may be mentioned the following general formula (2).

In the general formula (2), L represents a linking group having 1 to 10 carbon atoms, more preferably a linking group having 1 to 6 carbon atoms, particularly preferably a linking group having 2 to 4 carbon atoms, which is linear. Alternatively, it may have a branched structure, may have a ring structure, or may have a heteroatom selected from O, N, and S.
Preferred examples include * — (CH ₂ ) ₂ —O — **, * — (CH ₂ ) ₂ —NH — **, * — (CH ₂ ) ₄ —O — **, * — (CH ₂ ). _{6 -O - **, * - (} CH 2) 2 -O- (CH 2) 2 -O - **, * -CONH- (CH 2) 3 -O - **, * -CH 2 CH (OH ) CH ₂ —O — **, * —CH ₂ CH ₂ OCONH (CH ₂ ) ₃ —O — ** (* represents a linking site on the polymer main chain side, and ** represents a linking on the (meth) acryloyl group side) Represents a part). m represents 0 or 1;

  In general formula (2), X represents a hydrogen atom or a methyl group. From the viewpoint of curing reactivity, a hydrogen atom is more preferable.

  In the general formula (2), A represents a repeating unit derived from an arbitrary vinyl monomer, and is not particularly limited as long as it is a constituent component of a monomer copolymerizable with hexafluoropropylene. The polymer Tg (contributes to film hardness), solubility in solvents, transparency, slipperiness, dustproof / antifouling properties, etc., can be selected as appropriate, depending on the purpose. You may be comprised by the monomer.

  Preferred examples include methyl vinyl ether, ethyl vinyl ether, t-butyl vinyl ether, cyclohexyl vinyl ether, isopropyl vinyl ether, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, glycidyl vinyl ether, vinyl ethers such as allyl vinyl ether, vinyl acetate, vinyl propionate, butyric acid. (Meth) such as vinyl esters such as vinyl, methyl (meth) acrylate, ethyl (meth) acrylate, hydroxyethyl (meth) acrylate, glycidyl methacrylate, allyl (meth) acrylate, (meth) acryloyloxypropyltrimethoxysilane Acrylates, styrene, styrene derivatives such as p-hydroxymethylstyrene, crotonic acid, maleic acid, itaconic acid Can be mentioned unsaturated carboxylic acids and derivatives thereof, more preferably ether derivatives, vinyl ester derivatives, particularly preferably a vinyl ether derivative.

  x, y, and z represent mol% of each constituent component, and represent values satisfying 30 ≦ x ≦ 60, 5 ≦ y ≦ 70, and 0 ≦ z ≦ 65. Preferably, 35 ≦ x ≦ 55, 30 ≦ y ≦ 60, and 0 ≦ z ≦ 20, and particularly preferably 40 ≦ x ≦ 55, 40 ≦ y ≦ 55, and 0 ≦ z ≦ 10. However, x + y + z = 100.

  As a particularly preferred form of the fluorine-containing copolymer used in the present embodiment, general formula (3) may be mentioned.

In the general formula (3), X, x, and y have the same meaning as in the general formula (1), and preferred ranges are also the same.
n represents an integer of 2 ≦ n ≦ 10, preferably 2 ≦ n ≦ 6, and particularly preferably 2 ≦ n ≦ 4.
B represents a repeating unit derived from an arbitrary vinyl monomer, and may be composed of a single composition or a plurality of compositions. As an example, what was demonstrated as an example of A in the said General formula (5) is applicable.
Z1 and Z2 represent mol% of each repeating unit, and represent values satisfying 0 ≦ z1 ≦ 65 and 0 ≦ z2 ≦ 65. It is preferable that 0 ≦ z1 ≦ 30 and 0 ≦ z2 ≦ 10 respectively, and it is particularly preferable that 0 ≦ z1 ≦ 10 and 0 ≦ z2 ≦ 5. However, x + y + z1 + z2 = 100.

  In the fluorine-containing copolymer represented by the general formula (2), for example, a (meth) acryloyl group is introduced into a copolymer comprising a hexafluoropropylene component and a hydroxyalkyl vinyl ether component by any one of the methods described above. Can be synthesized.

  Although the preferable example of the fluorine-containing copolymer useful in this embodiment is shown below, this invention is not limited to these.

  The fluoropolymer can be polymerized by irradiation with ionizing radiation or heating in the presence of a photoacid generator or a thermal acid generator.

  The binder having a reactive crosslinking group of the low refractive index layer is preferably a binder having any of a (meth) acryloyl group, an epoxy group, and an isocyanate group as a reactive crosslinking group, and as a reactive crosslinking group ( More preferably, it is a binder having a (meth) acryloyl group.

  The copolymer used in this embodiment is synthesized after synthesizing a precursor such as a hydroxyl group-containing polymer by various polymerization methods such as solution polymerization, precipitation polymerization, suspension polymerization, precipitation polymerization, bulk polymerization, and emulsion polymerization. , By introducing a (meth) acryloyl group by the polymer reaction. The polymerization reaction can be performed by a known operation such as a batch system, a semi-continuous system, or a continuous system.

  The polymerization initiation method includes a method using a radical initiator, a method of irradiating light or radiation, and the like. These polymerization methods and polymerization initiation methods are, for example, the revised version of Tsuruta Junji “Polymer Synthesis Method” (published by Nikkan Kogyo Shimbun, 1971), Takatsu Otsu, Masato Kinoshita, “Experimental Methods for Polymer Synthesis” It is described in pp. 47-154 published in 1972.

  Among the above polymerization methods, a solution polymerization method using a radical initiator is particularly preferable. Solvents used in the solution polymerization method include, for example, ethyl acetate, butyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, tetrahydrofuran, dioxane, N, N-dimethylformamide, N, N-dimethylacetamide, benzene, toluene, acetonitrile, A single organic solvent such as methylene chloride, chloroform, dichloroethane, methanol, ethanol, 1-propanol, 2-propanol, and 1-butanol, or a mixture of two or more thereof may be used, or a mixed solvent with water may be used.

  The polymerization temperature needs to be set in relation to the molecular weight of the polymer to be produced, the type of initiator, etc., and can be from 0 ° C. or lower to 100 ° C. or higher, but it is preferable to carry out the polymerization in the range of 50 to 100 ° C.

Although the reaction pressure can be selected as appropriate, it is usually preferably 1 to 100 kg / cm ² , particularly about 1 to 30 kg / cm ² . The reaction time is about 5 to 30 hours.

  As the reprecipitation solvent for the obtained polymer, isopropanol, hexane, methanol and the like are preferable.

  The low refractive index layer-forming composition takes the form of a liquid, and is prepared by dissolving the binder and inorganic fine particles as essential components and, if necessary, various additives and a radical polymerization initiator in an appropriate solvent. The low refractive index layer-forming composition is applied onto the functional layer, dried, and crosslinked or polymerized by irradiation with ionizing radiation or heating to form a low refractive index layer.

  In addition, it is not always advantageous to add an additive such as a curing agent from the viewpoint of the film hardness of the low refractive index layer, but from the viewpoint of interfacial adhesion with the high refractive index layer, etc., a polyfunctional (meth) acrylate compound A small amount of a curing agent such as a polyfunctional epoxy compound, a polyisocyanate compound, an aminoplast, a polybasic acid, or an anhydride thereof may be added. When adding these, it is preferable that it is the range of 0-30 mass% with respect to the total solid of a low refractive index layer membrane | film | coat, It is more preferable that it is the range of 0-20 mass%, 0-10 mass % Range is particularly preferred.

  For the purpose of imparting properties such as antifouling properties, water resistance, chemical resistance, and slipping properties, known silicone-based or fluorine-based antifouling agents, slipping agents, and the like can be appropriately added. When these additives are added, it is preferably added in the range of 0.01 to 20% by mass of the total solid content of the low refractive index layer, more preferably in the range of 0.05 to 10% by mass. Particularly preferred is 0.1 to 5% by mass.

  Preferable examples of the silicone compound include those having a substituent at the terminal and / or side chain of a compound chain containing a plurality of dimethylsilyloxy units as repeating units. The compound chain containing dimethylsilyloxy as a repeating unit may contain a structural unit other than dimethylsilyloxy. The substituents may be the same or different, and a plurality of substituents are preferable. Examples of preferred substituents include acryloyl group, methacryloyl group, vinyl group, aryl group, cinnamoyl group, epoxy group, oxetanyl group, hydroxyl group, fluoroalkyl group, polyoxyalkylene group, carboxyl group, amino group and the like. It is done. Although there is no restriction | limiting in particular in molecular weight, It is preferable that it is 100,000 or less, It is more preferable that it is 50,000 or less, It is especially preferable that it is 3000-30000, It is most preferable that it is 10,000-20000. Although there is no restriction | limiting in particular in silicone atom content of a silicone type compound, it is preferable that it is 18.0 mass% or more, it is especially preferable that it is 25.0-37.8 mass%, and 30.0-37.0. Most preferably, it is mass%. Examples of preferable silicone compounds include X-22-174DX, X-22-2426, X-22-164B, X-22-164C, X-22-170DX, X-22-176D manufactured by Shin-Etsu Chemical Co., Ltd. X-22-1821 (trade name) manufactured by Chisso Corporation, FM-0725, FM-7725, FM-4421, FM-5521, FM6621, FM-1121, DMS-U22 manufactured by Gelest, RMS-033, Examples thereof include, but are not limited to, RMS-083, UMS-182, DMS-H21, DMS-H31, HMS-301, FMS121, FMS123, FMS131, FMS141, and FMS221 (hereinafter, trade names).

As the fluorine compound, a compound having a fluoroalkyl group is preferable. The fluoroalkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 10 carbon atoms, and a straight chain (for example, —CF ₂ CF ₃ , —CH ₂ (CF ₂ ) ₄ H, —CH ₂ (CF ₂ ) ₈ CF ₃ , -CH ₂ CH ₂ (CF ₂ ) ₄ H, etc.), even branched structures (eg CH (CF ₃ ) ₂ , CH ₂ CF (CF ₃ ) ₂ , CH (CH ₃ ) CF ₂ CF ₃ , CH (CH ₃ ) (CF ₂ ) ₅ CF ₂ H, etc.), alicyclic structures (preferably 5-membered or 6-membered rings such as perfluorocyclohexyl groups, perfluorocyclopentyl, etc. Group or an alkyl group substituted with these, and may have an ether bond (for example, CH ₂ OCH ₂ CF ₂ CF ₃ , CH ₂ CH ₂ OCH ₂ C ₄ F ₈ H, CH ₂ CH ₂ OCH ₂ CH ₂ C ₈ F ₁₇ , CH ₂ CH ₂ OCF ₂ CF ₂ OCF ₂ CF ₂ H, etc.). A plurality of the fluoroalkyl groups may be contained in the same molecule.
It is preferable that the fluorine-based compound further has a substituent that contributes to bond formation or compatibility with the low refractive index layer film. The substituents may be the same or different, and a plurality of substituents are preferable. Examples of preferred substituents include acryloyl group, methacryloyl group, vinyl group, aryl group, cinnamoyl group, epoxy group, oxetanyl group, hydroxyl group, polyoxyalkylene group, carboxyl group, amino group and the like. The fluorine-based compound may be a copolymer or a copolymer oligomer with a compound not containing a fluorine atom, and the molecular weight is not particularly limited. Although there is no restriction | limiting in particular in fluorine atom content of a fluorine-type compound, It is preferable that it is 20 mass% or more, It is especially preferable that it is 30-70 mass%, It is most preferable that it is 40-70 mass%. Examples of preferable fluorine-based compounds include Daikin Chemical Industries, Ltd., R-2020, M-2020, R-3833, M-3833 (named above), Dainippon Ink Co., Ltd., Megafac F-171. , F-172, F-179A, Defender MCF-300 (trade name) and the like, but are not limited thereto.

  For the purpose of imparting properties such as dust resistance and antistatic properties, a known cationic surfactant or a dustproof agent such as a polyoxyalkylene compound, an antistatic agent, or the like can be appropriately added. These dustproofing agent and antistatic agent may contain the structural unit as a part of the function in the above-mentioned silicone compound or fluorine compound. When these are added as additives, it is preferably added in the range of 0.01 to 20% by mass, more preferably in the range of 0.05 to 10% by mass of the total solid content of the low refractive index layer. Particularly preferred is 0.1 to 5% by mass. Examples of preferred compounds include, but are not limited to, Dainippon Ink Co., Ltd., MegaFace F-150 (trade name), Toray Dow Corning Co., Ltd., SH-3748 (trade name), and the like. Do not mean.

  The solvent used for the coating liquid for forming a functional layer (anti-glare hard coat layer) and a low refractive index layer in the antireflection film of this embodiment will be described below.

  Examples of the coating solvent include hexane (boiling point: 68.7 ° C .; hereinafter, “° C.” is omitted), heptane (98.4), cyclohexane (80.7), benzene (80 .1) hydrocarbons, dichloromethane (39.8), chloroform (61.2), carbon tetrachloride (76.8), 1,2-dichloroethane (83.5), trichloroethylene (87.2), etc. Halogenated hydrocarbons, diethyl ether (34.6), diisopropyl ether (68.5), dipropyl ether (90.5), ethers such as tetrahydrofuran (66), ethyl formate (54.2), acetic acid Esters such as methyl (57.8), ethyl acetate (77.1), isopropyl acetate (89), acetone (56.1), 2-tanone (= methyl ethyl) Ketones, ketones such as 79.6), alcohols such as methanol (64.5), ethanol (78.3), 2-propanol (82.4), 1-propanol (97.2), acetonitrile (81 .6), cyano compounds such as propionitrile (97.4), carbon disulfide (46.2), and the like.

Examples of the solvent having a boiling point exceeding 100 ° C. include octane (125.7), toluene (110.6), xylene (138), tetrachloroethylene (121.2), chlorobenzene (131.7), and dioxane (101.3). ), Dibutyl ether (142.4), isobutyl acetate (118), cyclohexanone (155.7), 2-methyl-4-pentanone (= MIBK, 115.9), 1-tanol (117.7), N, N-methylformamide (153), N, N-methylacetamide (166), dimethyl sulfoxide (189), and the like. Preferred are toluene, cyclohexanone, and 2-tyl-4-pentanone. Of these, ketones, aromatic hydrocarbons and esters are preferred, and ketones are particularly preferred. Among the ketones, 2-butanone is particularly preferable.
When a ketone solvent is used, either a single solvent or a mixture may be used. When mixing, the content of the ketone solvent is preferably 10% by mass or more of the total solvent contained in the coating composition. Preferably it is 30 mass% or more, More preferably, it is 60 mass% or more.

In the antireflection film of this embodiment, the functional layer and the low refractive index layer component are diluted with the solvent having the above-described composition, whereby the coating liquid for these layers is prepared. The concentration of the coating solution is preferably adjusted as appropriate in consideration of the viscosity of the coating solution and the specific gravity of the layer material, but is preferably 0.1 to 80% by mass, more preferably 1 to 60% by mass.
Further, the solvent for each functional layer and the low refractive index layer may have the same composition or may be different.

  In this embodiment, it is also preferable to use a dispersion stabilizer in combination with the coating liquid for forming each layer for the purpose of suppressing aggregation and sedimentation of inorganic fine particles, inorganic fillers and the like. As the dispersion stabilizer, polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivative, polyamide, phosphate ester, polyether, surfactant, silane coupling agent, titanium coupling agent and the like can be used. In particular, the above-mentioned silane coupling agent is preferable because the film after curing is strong.

(Transparent support)
As the transparent support of the antireflection film of the present embodiment, it is preferable to use a plastic film. Examples of the polymer forming the plastic film include cellulose acylate (eg, triacetyl cellulose, diacetyl cellulose, typically TAC-TD80U, TD80UF, etc. manufactured by Fuji Photo Film), polyamide, polycarbonate, polyester (eg, polyethylene terephthalate, Polyethylene naphthalate), polystyrene, polyolefin, norbornene-based resin (Arton: trade name, manufactured by JSR), amorphous polyolefin (ZEONEX: trade name, manufactured by Nippon Zeon), and the like. Of these, triacetyl cellulose, polyethylene terephthalate, and polyethylene naphthalate are preferable, and triacetyl cellulose is particularly preferable.
Triacetyl cellulose consists of a single layer or a plurality of layers. A single-layer triacetyl cellulose is produced by drum casting or band casting disclosed in JP-A-7-11055 and the like. It is prepared by the so-called co-casting method disclosed in JP-A-61-94725 and JP-B-62-43846. That is, the raw material flakes are solvents such as halogenated hydrocarbons (dichloromethane, alcohols (methanol, ethanol, butanol, etc.), esters (methyl formate, methyl acetate, etc.), ethers (dioxane, dioxolane, diethyl ether, etc.), etc. A solution (called a dope) with various additives such as a plasticizer, an ultraviolet absorber, an anti-degradation agent, a slipping agent, and a peeling accelerator is added to the horizontal endless as necessary. When casting by a dope supply means (called a die) on a support composed of a metal belt or a rotating drum, a single dope is cast in a single layer if it is a single layer, and a high concentration in the case of multiple layers. A low-concentration dope is co-cast on both sides of the cellulose ester dope, and the film is dried to some extent on the support to release the rigid film, and then peeled off from the support. A process comprising passed through a drying section by species of the conveying means to remove the solvent.

A typical solvent for dissolving triacetylcellulose as described above is dichloromethane. However, from the viewpoint of the global environment and working environment, the solvent preferably does not substantially contain a halogenated hydrocarbon such as dichloromethane. “Substantially free” means that the proportion of halogenated hydrocarbon in the organic solvent is less than 5% by mass (preferably less than 2% by mass).
In preparing a triacetyl cellulose dope using a solvent substantially free of dichloromethane or the like, a special dissolution method as described later is essential.

  The first dissolution method is called a cooling dissolution method and will be described below. First, triacetyl cellulose is gradually added to a solvent at a temperature around room temperature (-10 to 40 ° C.) while stirring. The mixture is then cooled to -100 to -10 ° C (preferably -80 to -10 ° C, more preferably -50 to -20 ° C, most preferably -50 to -30 ° C). The cooling can be performed, for example, in a dry ice / methanol bath (−75 ° C.) or a cooled diethylene glycol solution (−30 to −20 ° C.). When cooled in this manner, the mixture of triacetyl cellulose and solvent solidifies. Furthermore, when this is heated to 0 to 200 ° C. (preferably 0 to 150 ° C., more preferably 0 to 120 ° C., most preferably 0 to 50 ° C.), a solution in which triacetyl cellulose flows in the solvent is obtained. The temperature may be increased by simply leaving it at room temperature or in a warm bath.

  The second method is called a high temperature melting method and will be described below. First, triacetyl cellulose is gradually added to a solvent at a temperature around room temperature (-10 to 40 ° C.) while stirring. The triacetylcellulose solution is preferably swollen beforehand by adding triacetylcellulose to a mixed solvent containing various solvents. In this method, the dissolution concentration of triacetyl cellulose is preferably 30% by mass or less, but is preferably as high as possible from the viewpoint of drying efficiency during film formation. Next, the organic solvent mixed solution is heated to 70 to 240 ° C. under a pressure of 0.2 MPa to 30 MPa (preferably 80 to 220 ° C., more preferably 100 to 200 ° C., most preferably 100 to 190 ° C.). Next, since these heated solutions cannot be applied as they are, it is necessary to cool them below the lowest boiling point of the solvent used. In that case, it is common to cool to -10-50 degreeC and to return to a normal pressure. For cooling, the high-pressure and high-temperature vessel or line containing the triacetylcellulose solution may be left at room temperature, and more preferably, the apparatus may be cooled using a coolant such as cooling water. A cellulose acetate film substantially free of halogenated hydrocarbons such as dichloromethane and a process for producing the same are disclosed in JIII Journal of Technical Disclosure (Publication No. 2001-1745, published on March 15, 2001, hereinafter Published Technical Report 2001-1745). (Abbreviated as No.).

  When the antireflection film of this embodiment is used in a liquid crystal display device, it is disposed on the outermost surface of the display by providing an adhesive layer on one side. Moreover, you may combine the antireflection film and polarizing plate of this embodiment. When the transparent support is triacetyl cellulose, triacetyl cellulose is used as a protective film for protecting the polarizing film of the polarizing plate. Therefore, it is preferable in terms of cost to use the antireflection film of this embodiment as it is for the protective film. .

The antireflection film of the present embodiment is transparently supported for sufficient adhesion when it is placed on the outermost surface of a display by providing an adhesive layer on one side or used as a protective film for a polarizing plate as it is. It is preferable to carry out a saponification treatment after forming the outermost layer on the body. The saponification treatment is performed by a known method, for example, by immersing the film in an alkali solution for an appropriate time. After being immersed in the alkaline solution, it is preferable to sufficiently wash with water or neutralize the alkaline component by dipping in a dilute acid so that the alkaline component does not remain in the film.
By saponification treatment, the surface of the transparent support opposite to the side having the outermost layer is hydrophilized.
The hydrophilized surface is particularly effective for improving the adhesion with a polarizing film containing polyvinyl alcohol as a main component. In addition, the hydrophilic surface makes it difficult for dust in the air to adhere to it, so that it is difficult for dust to enter between the polarizing film and the antireflection film when adhered to the polarizing film, and this prevents point defects caused by dust. It is valid.
The saponification treatment is preferably carried out so that the contact angle of water on the surface of the transparent support opposite to the side having the outermost layer is 40 ° or less. More preferably, it is 30 ° or less, particularly preferably 20 ° or less.

Specific means for the alkali saponification treatment can be selected from the following two means (I) and (II). (I) is superior in that it can be processed in the same process as a general-purpose triacetyl cellulose film, but since the saponification is performed up to the antireflection film surface, the surface is alkali-hydrolyzed and the film deteriorates. The point that it becomes dirty when the liquid remains can be a problem. In that case, although it becomes a special process, (II) is excellent.
(I) After the antireflection layer is formed on the transparent support, the back surface of the film is saponified by immersing it in an alkaline solution at least once.
(II) Before or after the formation of the antireflection layer on the transparent support, the alkaline liquid is applied to the surface of the antireflection film opposite to the surface on which the antireflection film is formed, and is heated, washed and / or washed. By summing, only the back surface of the film is saponified.

(Application method)
The antireflection film of this embodiment can be formed by the following method, but is not limited to this method.

First, a coating solution containing components for forming each layer is prepared. Next, a coating solution for forming a functional layer is applied on a transparent support by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method or a die coating method, Although heated and dried, the micro gravure coating method, the wire bar coating method, and the die coating method are more preferable, and the die coating method is particularly preferable. Further, it is most preferable to apply using a die whose configuration is devised as described later.
Thereafter, the monomer for forming the functional layer is polymerized and cured by light irradiation or heating. Thereby, a functional layer is formed. If necessary, the functional layer can be a plurality of layers.
Next, in the same manner, a coating solution for forming a low refractive index layer is applied onto the functional layer, and light irradiation or heating is performed to form the low refractive index layer. In this way, the antireflection film of this embodiment is obtained.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

  In this embodiment, a digital camera S3Pro manufactured by Fuji Photo Film Co., Ltd. was used as the above-described light detection device 11. As a lens to be attached to the digital camera, Ai AF Zoom Nikkor ED70-180mm F4.5-F5.6D manufactured by Nikon Corporation was used. As the fluorescent lamps 12 and 13 described above, Sunlight Wide Line SW-270 manufactured by LPL Corporation was used. As the computer 20, a computer having a storage medium such as a hard disk storing software for converting luminance values into density values, in addition to a known CPU, ROM, RAM, display, and user interface was used. This computer is connected to a digital camera via an IEEE 1394 cable. It should be noted that alignment of the sample stage, adjustment of the height of the fluorescent lamp, photographing with a digital camera, and the like may be easily performed by remote control from a computer.

  First, in the present example, an antireflection film that is an evaluation value calculation target is created.

(Preparation of antiglare hard coat layer coating solution and low refractive index layer coating solution)
────────────────────────────────────
Composition of coating solution for antiglare hard coat layer ────────────────────────────────────
PET-30 50.0g
Irgacure 184 2.0g
SX-350 (30%) 1.5g
Cross-linked acrylic-styrene particles (30%) 13.0 g
FP-1 0.75g
Sol liquid a-2 10.0g
Toluene 38.5g
────────────────────────────────────

  The coating solution was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution for an antiglare hard coat layer.

  Here, the compounds used are as follows. PET-30: a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (manufactured by Nippon Kayaku Co., Ltd.), DPHA: a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.), Irgacure 184: Polymerization initiator (Ciba Specialty Chemicals Co., Ltd.), SX-350: Cross-linked polystyrene particles having an average particle size of 3.5 μm (refractive index: 1.60, manufactured by Soken Chemical Co., Ltd., 30% toluene dispersion , Used after dispersion for 20 minutes at 10,000 rpm in a Polytron disperser), crosslinked acrylic-styrene particles: average particle size 3.5 μm (refractive index 1.55, manufactured by Soken Chemical Co., Ltd., 30% toluene dispersion, Polytron disperser Used after dispersion at 10,000 rpm for 20 minutes), FP-1: Fluorine series It is a surface modifier.

────────────────────────────────────
Composition of coating solution for low refractive index layer ────────────────────────────────────
Fluoropolymer B (6%) 13.0g
MEK-ST-L (30%) 1.0 g
Sol liquid a-1 0.5g
MEK 5.0g
Cyclohexanone 0.5g
────────────────────────────────────
The solution was stirred and then filtered through a polypropylene filter having a pore size of 1 μm to prepare a coating solution for a low refractive index layer.

  Here, the compounds used are as follows. Fluoropolymer B: 80 g of the fluoropolymer described in Example 1 of JP-A-11-189621, 2020 g of Cymel 303 as a curing agent (Nippon Cytec Industries, Ltd.), 2.0 g of Catalyst 4050 as a curing catalyst (Japan) Cytec Industries Co., Ltd.) dissolved in MEK to 6% (refractive index 1.44, solid content concentration 6%, manufactured by JSR Corporation), MEK-ST-L: colloidal silica dispersion (MEK- ST particle size difference, average particle size 45 nm, solid content concentration 30%, manufactured by Nissan Chemical Co., Ltd.).

(Coating of antiglare hard coat layer)
An 80 μm-thick triacetyl cellulose film (TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) is unwound in a roll and directly coated with a coating solution for antiglare hard coat layer at 135 lines / inch and a depth of 60 μm. Using a microgravure roll with a diameter of 50 mm and a doctor blade having a gravure pattern, the coating was performed at a conveyance speed of 10 m / min, dried at 60 ° C. for 150 seconds, and further air-cooled metal halide lamp of 160 W / cm under nitrogen purge (Eye Graphics Co., Ltd.) is used to cure the coating layer by irradiating with ultraviolet light having an illuminance of 400 mW / cm ² and an irradiation amount of 250 mJ / cm ² to form an antiglare hard coat layer (thickness 6 μm). And wound up.

(Coating of low refractive index layer)
The triacetyl cellulose film coated with the antiglare hard coat layer is unwound again, and the low refractive index layer coating liquid is a microgravure roll having a diameter of 200 lines / inch and a gravure pattern with a depth of 30 μm and a diameter of 50 mm. And a doctor blade at a transfer speed of 20 m / min, dried at 120 ° C. for 75 seconds, further dried for 10 minutes, and then air-cooled metal halide lamp (I graphics ( Was used to irradiate ultraviolet rays having an illuminance of 400 mW / cm ² and an irradiation amount of 240 mJ / cm ² to form a low refractive index layer having a thickness of 100 nm and wound up.

  Thus, an antireflection film was prepared.

(Sample preparation)
By the method described in the above embodiment, the prepared antireflection film was rubbed, and black PET was attached to the back surface thereof to prepare a sample. Samples prepared were a sample A prepared by a test by an eraser rubbing method and a sample B prepared by a test by a steel wool method. The rubbing conditions in the eraser rubbing method were the conditions in which the number of rubbing of the rubbing member was 200 reciprocations in the rubbing condition example described in the above embodiment. The rubbing conditions in the steel wool method were the conditions in which the number of rubbing of the rubbing member was 10 reciprocations in the rubbing condition examples described in the above embodiment.

(Evaluation of antireflection film)
Evaluation values were calculated for each of the prepared samples A and B by the method described with reference to FIG. As a result, both the sample A and the sample B had an evaluation value of 0.1 or less. Moreover, as a result of visually observing each of the sample A and the sample B, it was possible to evaluate that both of the performance degradations had no practical problem. As a result, it was found that if the evaluation value is 0.1 or less under the rubbing conditions used in this example, it can be said to be an antireflection film having high scratch resistance.

The figure which shows the flow of the abrasion-resistant performance evaluation method of the surface film for demonstrating embodiment of this invention The figure which shows schematic structure of the evaluation value calculation system which calculates the evaluation value for quantitatively evaluating the abrasion resistance performance of a surface film FIG. 2 is a diagram illustrating a flow when calculating an evaluation value using the evaluation value calculation system.

Explanation of symbols

5 Sample stand 6 Sample 11 Photodetector 12, 13 Fluorescent lamp 20 Computer

Claims (7)

A method for evaluating the scratch resistance of a surface film for evaluating the scratch resistance of a surface film attached to the surface of a flat panel display,
Rubbing step of rubbing the surface film according to predetermined conditions;
A reflected light detection step of detecting first reflected light from the rubbed portion of the surface film and second reflected light from the non-rubbed portion;
A density calculating step for obtaining a first density according to the light quantity of the first reflected light and a second density according to the light quantity of the second reflected light;
A scratch resistance evaluation method for a surface film, comprising: an evaluation step for evaluating the scratch resistance based on a difference between the first concentration and the second concentration. A scratch resistance evaluation method for a surface film according to claim 1,
In the rubbing step, the surface film is rubbed with an eraser. A scratch resistance evaluation method for a surface film according to claim 1,
In the rubbing step, the surface film is rubbed with steel wool. A scratch resistance evaluation method for a surface film according to any one of claims 1 to 3,
A method for evaluating the scratch resistance performance of a surface film, which specifies the number of rubbing times of the surface film and a load applied to the surface film as the predetermined condition. A scratch resistance evaluation method for a surface film according to any one of claims 1 to 4,
A method for evaluating the scratch resistance of a surface film, wherein the surface film is an antireflection film. A surface film that is attached to the surface of a flat panel display,
The surface film whose difference of the said 1st density | concentration and the said 2nd density | concentration was 0.1 or less as a result of performing the abrasion-resistant performance evaluation method in any one of Claims 1-4. The surface film according to claim 6,
The surface film in which the surface film includes an antireflection film.

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