JP5218868B2 - Method for producing antireflection film with improved water / oil repellency and scratch resistance - Google Patents

Description

The present invention relates to a method for producing an antireflection film used on the surface of optical articles such as liquid crystal displays and plasma displays, which has a low refractive index layer, which has water and oil repellency and also has scratch resistance. About.

  In order to improve the visibility of a display surface of an optical article such as a liquid crystal display or a plasma display, it is required that the reflection of light emitted from an external light source such as a fluorescent lamp is small. In order to perform such antireflection, an antireflection film in which a low refractive index layer having a refractive index lower than the refractive index of the lower layer is formed on an optical article directly or via another layer on a transparent plastic substrate film. It is done to stick on the surface of. The low refractive index layer in the antireflection film needs to have a low refractive index. However, since it is disposed on the outermost surface of the display, the antireflective film further has a repellent property to prevent contamination due to adhesion of water or oil. It is necessary to impart water resistance and oil repellency, and to impart scratch resistance to prevent scratches.

  In JP-A-2002-82206 (Patent Document 1) and JP-A-2003-202406 (Patent Document 2), a low refractive index layer (antireflection layer) is used to impart anti-contamination properties to the antireflection film. It is shown that a water repellent layer is laminated thereon. Since the water repellent layer of Patent Document 2 directly faces the surface of the antireflection film, there is a problem that the scratch resistance is poor. In order to solve such a problem of scratch resistance, it is possible to ensure scratch resistance as an antireflection film by imparting scratch resistance to a layer other than the water repellent layer which is the outermost surface layer. Has been done. However, in such an antireflection film, in order to impart stain resistance and scratch resistance, a water repellent / oil repellent layer and a scratch resistant layer are separately provided in addition to the low refractive index layer (antireflection layer). An increase in the manufacturing process is inevitable.

  In JP-A-8-211202 (Patent Document 3), light in which an antireflection film comprising a large number of antireflection ultrafine particles coated with a fluorine-containing silane compound having water and oil repellency is formed on a transparent substrate. A reflector is shown. The ultrafine particles of Patent Document 3 are fixed by firing at 200 ° C. with a binder of ethyl silicate. In the technique requiring high-temperature firing as in Patent Document 3, a plastic film substrate that is heat-sensitive is used. An antireflection film cannot be made.

JP 2002-82206 A JP 2003-202406 A JP-A-8-211202

The present invention relates to a method for producing an antireflection film having a low refractive index layer formed on a plastic film substrate, with or without other layers, having water and oil repellency and scratch resistance. The purpose is to provide.

The manufacturing method of the antireflection film of the present invention for solving the above-described problem is a method for forming an antireflection film, which forms a low refractive index layer as an outermost surface layer directly or through another layer on a transparent plastic substrate film. In the production method, the low refractive index layer contains silica fine particles having voids subjected to a treatment for introducing a water- and oil-repellent group and a treatment for introducing a crosslinking group. Silica fine particles having voids subjected to the treatment of introducing an oily group and the treatment of introducing a crosslinking group are produced using the following steps 1) to 3) :
1) A step of increasing the activity of silanol groups on the surface of silica fine particles by removing impurity ions by pretreating silica fine particles having voids with an ion exchange resin;
2) a step of introducing a water- and oil-repellent group by adding a water- and oil-repellent treatment agent to silica fine particles having voids with enhanced activity of the silanol group, and heating;
3) A step of introducing a crosslinking group by adding a compound having a crosslinkable group to the silica fine particles having voids into which the water / oil repellent group has been introduced, and refluxing .
The amount of the water / oil repellent treatment agent applied to the silica fine particles is 3 to 25 parts by mass with respect to 100 parts by mass of the silica fine particles, and the silica fine particles are treated with the compound having a crosslinkable group. The amount is 5 to 25 parts by mass with respect to 100 parts by mass of silica fine particles, and the total amount of the water / oil repellent treatment agent and the compound having a crosslinkable group is 100 parts by mass of silica fine particles. On the other hand, it is a manufacturing method of the antireflection film characterized by being 8 mass parts-30 mass parts.

  The silica fine particles having voids contained in the low refractive index layer are compounds having a crosslinkable group (curing treatment agent) after the introduction of the water / oil repellent group by the water / oil repellent treatment agent. Thus, it is desirable to introduce a crosslinkable group.

  In this specification, “water / oil repellency” means both water repellency and oil repellency, or either water repellency or oil repellency.

  The silica fine particles are reacted with both the water / oil repellent treating agent and the curable treating agent to obtain water repellent / scratch resistant silica fine particles. Silica fine particles can be treated with a water- and oil-repellent compound and a curable compound in the order of a water- and oil-repellent treatment agent, followed by a curable treatment agent. It is preferable for preventing the appearance from being damaged.

In order to further impart scratch resistance to the antireflection film obtained by the production method of the present invention, a hard coat layer is optionally provided between the transparent plastic substrate film and the low refractive index layer. It may be provided. In order to impart antistatic properties to the antireflection film of the present invention, an antistatic layer may be provided between the transparent plastic substrate film and the low refractive index layer as necessary.

In the antireflective film obtained by the production method of the present invention, the low refractive index layer has a water repellent / oil repellent group introduced by a water repellent / oil repellent treatment and a compound having a crosslinkable group (curing treatment agent). since) is by crosslinking group contains silica fine particles having an introduced treated voids, antireflective film obtained by the producing method of the present invention, there is stain resistance to oil and / or water, and, Excellent scratch resistance.

<About the processing method of silica fine particles>
Silica fine particles The silica fine particles used in the present invention are “silica fine particles having voids” having a refractive index lower than that of ordinary silica fine particles. The term “fine particles having voids” means that the gas has a structure in which gas is filled and / or a porous structure containing gas, or the fine particles form an aggregate, so that the gas has a refractive index of 1.0. In the case of air, the fine particles and their aggregates whose refractive index has decreased in inverse proportion to the occupancy ratio of air in the fine particles compared to the original refractive index of the fine particles. The average particle diameter of the fine particles is 5 nm or more and 300 nm or less, preferably the lower limit is 8 nm or more and the upper limit is 100 nm or less, more preferably the lower limit is 10 nm or less and the upper limit is 80 nm or less. When the average particle diameter of the silica fine particles is within this range, excellent transparency can be imparted to the low refractive index layer.

  When imparting water repellency and scratch resistance to the surface of the silica fine particles, the silica fine particles may be used as they are without pretreatment. Preferably, however, as a pretreatment, the silica fine particles are surfaced using an ion exchange resin or the like. After enhancing the activity of the silanol group, water / oil repellent treatment and scratch resistance treatment are preferably performed.

Water repellent / oil repellent treatment agent As a method of introducing a water repellent group on the surface of silica fine particles, there are many silanol groups on the surface of the silica fine particles, so this silanol group reacts with a hydrophobic compound having a hydrophobic group. A method for introducing a water-repellent group by treating, a method for treating the surface of silica fine particles with a surfactant having a hydrophobic group, a method for coating the surface of silica fine particles with a polymer having a hydrophobic group, containing a hydrophobic group There is a method in which the plasma polymerized film is light-watered on the silica surface in the presence of gas.

  Examples of the hydrophobic compound having a hydrophobic group include hydrophobic compounds containing a perfluoro group, an alkyl group, a trimethylsilyl group, a dimethylsilylene group, a phenyl group, a polydimethylsiloxane segment, and the like. Among these hydrophobic compounds, it is particularly preferable to combine a compound having a perfluoroalkyl group having both water repellency and oil repellency with a silanol group on the surface of the silica fine particles because water and oil repellency can be imparted.

  As a method for perfluoroalkylation on the surface of the silica fine particles, a method of reacting a metal alkoxy compound containing at least one perfluoroalkyl group, a metal halogen compound, a metal isocyanate compound or the like with a silanol group on the surface of the silica fine particles, Examples thereof include a method of treating silica fine particles with a fluorosurfactant, a method of coating silica fine particles with a polymer having a fluoroalkyl group, and a method of forming a plasma polymerized film on the surface of silica fine particles in the presence of a fluorine-containing gas. Among these, it is desirable to use a metal alkoxy compound, a metal halogen compound, and a metal isocyanate compound as a water / oil repellency treatment agent. Among metal compounds, a compound containing silicon is most preferable.

  Examples of the perfluoroalkyl group-containing compound include 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3,3,3-trifluoropropyltriisopropoxysilane, 3 , 3,3-trifluoropropyltrichlorosilane, 3,3,3-trifluoropropyltriisocyanate silane, 2-perfluorooctyltrimethoxysilane, 2-perfluorooctylethyltriethoxysilane, 2-perfluorooctylethyltri Examples include isopropoxysilane, 2-perfluorooctylethyltrichlorosilane, and 2-perfluorooctyl isocyanate silane.

  The perfluoroalkyl group has a water / oil repellency improvement structure in which the end of the perfluoroalkyl group is a trifluoro group (CF3) and the length of the alkyl chain of the perfluoroalkyl group is (CF2) 3 or more. Preferably there is. Further, a compound in which the terminal described above has both a trifluoro group (CF3) and an alkyl chain length of (CF2) 3 or more is most preferable.

Compound having a crosslinkable group (curable agent)
Since silica fine particles and binder resin are bonded by introducing a crosslinkable group by treating with a compound having a crosslinkable group into silica fine particles subjected to water / oil repellency treatment, the silica fine particles are contained. The coating film has improved scratch resistance. As a method for introducing the crosslinkable group into the silica fine particles, the same method as the method for introducing the water / oil repellent compound into the silica fine particles can be used. For example, a metal alkoxy compound having one or more crosslinkable groups Metal halide compounds and metal isocyanate compounds can be used. Examples of the crosslinkable group include those in which the reaction proceeds by a polymerization reaction such as photo radical polymerization, photo cation polymerization, or photo anion polymerization, or a reaction mode such as addition polymerization or condensation polymerization that proceeds through photodimerization. Among them, in particular, an ethylenically unsaturated bond group such as an acrylic group, a vinyl group, and an allyl group is directly irradiated by an ionizing radiation such as an ultraviolet ray or an electron beam, or indirectly by receiving an action of an initiator. A photo-radical polymerization reaction is caused, and it is preferable because it is relatively easy to handle including a photocuring step.

Surface treatment In the above water / oil repellency treatment and crosslinkable group introduction treatment, a compound having a crosslinkable group (curing treatment agent) is prepared after reacting the water / oil repellency treatment agent on the surface of the silica fine particles. It is preferable to react to introduce a crosslinkable group. This is because by performing the water / oil repellency treatment and the crosslinkable group introduction treatment in this order, it is possible to prevent the unreacted water / oil repellency compound from decreasing and to impair the appearance of the coating film surface.

  The processing amount of the water / oil repellent treatment agent to the silica fine particles is preferably 3 parts by mass to 25 parts by mass with respect to 100 parts by mass of the silica fine particles. If the amount is 3 parts by mass or less, water / oil repellency cannot be imparted, and if it is 25 parts by mass or more, the appearance of the coating film is impaired. The amount of the curable treatment agent applied to the silica fine particles is preferably 5 to 25 parts by mass with respect to 100 parts by mass of the silica fine particles. If it is 5 parts by mass or less, the strength of the coating film cannot be obtained, and if it is 25 parts by mass or more, improvement of the film strength cannot be obtained.

  When combining the water / oil repellent treatment agent and the curable treatment agent, the total amount of both treatments is preferably 8 to 30 parts by mass with respect to 100 parts by mass of the silica fine particles. If it is 8 parts by mass or less, it is difficult to achieve both water and oil repellency and film strength. Moreover, when it is 30 mass parts or more, the external appearance of a coating film will be impaired.

<About the creation of a low refractive index layer>
The low-refractive index layer is a coating for a low-refractive index layer formed by mixing and dispersing silica fine particles subjected to the above water / oil repellency treatment and curable treatment in an ionizing radiation curable resin and a solvent as a binder resin. The composition is formed by coating and ionizing radiation curing so as to be lower than the refractive index of the lower layer. The following can be used for the ionizing radiation curable resin and the solvent.

  The coating composition for the low refractive index layer is, for example, spin coating method, dip method, spray method, slide coating method, bar coating method, roll coater method, meniscus coater method, flexographic printing method, screen printing method, bead coater method, etc. It can apply | coat on a base material with these various methods. The coated material is usually dried as necessary, and then a low refractive index layer is formed by irradiating and curing ionizing radiation such as ultraviolet rays and electron beams.

Ionizing radiation curable resins Ionizing radiation curable resins undergo a reaction that causes polymerization or dimerization to proceed directly when irradiated with ionizing radiation or indirectly through the action of an initiator. Monomers, oligomers and polymers having a polymerizable functional group to wake up can be used. Specifically, radically polymerizable monomers and oligomers having an ethylenically unsaturated bond such as an acryl group, a vinyl group, and an allyl group are preferable, and polymerization is performed in one molecule so that cross-linking occurs between molecules of the binder component. It is desirable that it is a polyfunctional binder component having 2 or more, preferably 3 or more functional functional groups. However, other ionizing radiation curable binder components may be used. For example, a photocationically polymerizable monomer or oligomer such as an epoxy group-containing compound may be used.

  When the binder resin is a photocurable resin, it is desirable to use a photoinitiator to initiate radical polymerization. The photoinitiator is not particularly limited, and examples thereof include acetophenones, benzophenones, ketals, anthraquinones, disulfide compounds, thiuram compounds, and fluoroamine compounds.

An organic solvent for dissolving and dispersing the solvent solid component is essential and the type thereof is not limited, but alcohols such as methanol, ethanol and isopropyl alcohol; ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; ethyl acetate And esters such as butyl acetate; halogenated hydrocarbons; and aromatic hydrocarbons such as toluene and xylene.

<About making antireflection film>
Transparent plastic substrate film The material of the transparent plastic substrate film is not particularly limited, but general materials used for antireflection films can be used, such as triacetate cellulose (TAC), polyethylene terephthalate (PET), diacetyl. Films made of various resins such as cellulose, acetate butyrate cellulose, polyethersulfone, acrylic resin, polyurethane resin, polyester, polycarbonate, polysulfone, polyether, trimethylpentene, polyetherketone, (meth) acrylonitrile, etc. It can be illustrated. The thickness of the substrate is usually about 25 μm to 1000 μm.

Hard coat layer The hard coat layer may be formed on the antireflection laminate as necessary for the purpose of improving performance such as scratch resistance and strength. The “hard coat layer” refers to a layer having a hardness of “H” or higher in a pencil hardness test specified in JIS 5600-5-4: 1999.

  The hard coat layer is preferably formed using an ionizing radiation curable resin composition, and more preferably has a (meth) acrylate-based functional group, such as a relatively low molecular weight polyester resin or polyether resin. , Acrylic resin, epoxy resin, urethane resin, alkyd resin, spiroacetal resin, polybutadiene resin, polythiol polyether resin, polyhydric alcohol, ethylene glycol di (meth) acrylate, pentaerythritol di (meth) acrylate monostearate, etc. (Meth) acrylate; tri (meth) acrylate such as trimethylolpropane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; pentaerythritol tetra (meth) acrylate derivative, dipentaerythritol Monomers as polyfunctional compounds such as penta (meth) acrylate; or may use oligomers such as epoxy acrylate or urethane acrylate.

  The hard coat layer can be formed by the same method as the low refractive index layer.

Antistatic layer The antistatic layer may be provided in the antireflection laminate as necessary in order to suppress the generation of static electricity, to eliminate the adhesion of dust, and to suppress the electrostatic damage from the outside. The antistatic layer preferably has a function of reducing the surface resistance value of the antireflection laminate to 1012 Ω / □ or less. On the other hand, even if the surface resistance value is 1012 Ω / □ or more, it is possible to suppress the generation of static electricity. An antistatic layer is preferably provided as long as the above functions can be exhibited.

  The coating composition for forming the antistatic layer may be an ink-made one, or may be prepared by combining conductive fine particles, ionizing radiation curable resin, solvent, other components, and the like. In order to prepare a coating composition for forming an antistatic layer using each of the above components, it may be dispersed according to a general method for preparing a coating solution. For example, if the conductive fine particles are in the form of a colloid, they can be mixed as they are, and if they are in the form of powder, a medium such as beads is put into the obtained mixture, and it is appropriately used with a paint shaker or a bead mill. By carrying out the dispersion treatment, a composition for forming an antistatic layer for coating can be obtained.

  Coating compositions for forming an antistatic layer include, for example, spin coating, dip, spray, slide coating, bar coating, roll coater, meniscus coater, flexographic printing, screen printing, bead coater, etc. It can apply | coat on a base material with these various methods. The coated material is usually dried and cured as necessary, or an antistatic layer is formed by curing by irradiating with ionizing radiation such as ultraviolet rays or electron beams.

Examples 1 and 2 and Comparative Examples 1 to 4 Production of an antireflection film comprising transparent plastic substrate film / hard coat layer / low refractive index layer of Examples 1 and 2 and Comparative columns 1 to 4 is as follows. I went there.

  On the laminated film consisting of a transparent plastic substrate film / hard coat layer, a coating composition for forming a low refractive index layer having the composition shown below is bar-coated, and after removing the solvent by drying, an ultraviolet irradiation device (fusion UV system) Made by Japan Co., Ltd.), an ultraviolet ray is irradiated at an irradiation dose of 260 mJ / cm @ 2, the coating film is cured, and the film thickness of the refractive index layer is about 100 nm. A laminate (antireflection film) comprising a refractive index layer was obtained. As the silica sol having the surface-treated voids, those obtained in Examples 1 and 2 and Comparative Examples 1 to 4 below were used.

Preparation of coating composition for forming low refractive index layer A composition for forming a low refractive index layer was prepared by mixing the components of the following composition.

Silica sol (10% methyl isobutyl ketone solution) with surface-treated voids
28.56 parts by mass Pentaerythritol triacrylate (PETA) 1.90 parts by mass Irgacure 907 (trade name, manufactured by Ciba Specialty Chemicals) 0.02 parts by mass Irgacure 184 (trade name, manufactured by Ciba Specialty Chemicals) 0.07 mass Part TSF4460 (trade name, manufactured by GE Toshiba Silicone Co., Ltd.) 0.24 parts by mass Methyl isobutyl ketone 69.21 parts by mass

<Evaluation method>
The reflectance was measured using a spectrophotometer (manufactured by Shimadzu Corporation, UV-3100PC: trade name) equipped with a minimum reflectance 5 ° C. regular reflection measuring device. In addition, the reflectivity shows a value (minimum reflectivity) when it becomes a minimum value near a wavelength of 550 nm.

Scratch resistance evaluation test The surface of the antireflection laminate was subjected to 30 reciprocating frictions using a # 0000 steel wool with a predetermined friction load (200 g), and the surface of the antireflection laminate was not damaged. The scratch resistance of the antireflection laminate was evaluated with Δ for those having 1 to 10 scratches and x for those with 10 or more scratches.

Contact angle measurement Using a microscope contact angle meter CA-QI series manufactured by Kyowa Interface Science Co., Ltd., water repellency was measured with water, and oil repellency was measured with liquid paraffin.

[Example 1] (Surface treatment of silica fine particles)
Overnight ion exchange resin (AG r 501-x8 (D) Resin: trade name, BIO-RAD Laboratories INC.) 93 parts by mass of silica sol (10% solution of isopropyl alcohol) having voids from which impurity ions have been removed 0.5 parts by mass of a fluorine-based silane coupling agent (TSL-8233: trade name, manufactured by Toshiba Silicone) was added, and 5.5 parts by mass of isopropyl alcohol was added as a solvent. Water was further added to the obtained mixture. The amount of water added was 3 mol per 1 mol of the fluorinated silane coupling agent. Moreover, after adjusting the whole solution to pH = 4 with HCl aqueous solution, it heated and stirred at 80 degreeC for 2.5 hours. Next, 1 part by mass of a methacrylic silane coupling agent (KBM-503: trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) is added to the processed product, and the mixture is further refluxed and stirred at 80 ° C. for 2.5 hours. Water- and oil-repellent and scratch-resistant silica fine particles were obtained. The prepared solution was subjected to solvent substitution from isopropyl alcohol to methyl isobutyl ketone.

[Example 2] (Surface treatment of silica fine particles)
In the surface treatment of the silica fine particles of Example 1, the same treatment as in Example 1 was performed except that the fluorine-based silane coupling agent (TSL-8233: trade name, manufactured by Toshiba Silicone) was changed to 1 part by mass. The surface-treated silica fine particles of Example 2 were obtained.

[Comparative Example 1]
Silica sol (10% solution of isopropyl alcohol) having voids from which impurity ions were removed with an ion exchange resin overnight was used.

[Comparative Example 2]
In the surface treatment of the silica fine particles of Example 1, the same treatment as in Example 1 was performed except that the treatment with the methacrylic silane coupling agent was not performed, and the surface-treated silica fine particles of Comparative Example 2 were obtained.

[Comparative Example 3]
In the surface treatment of the silica fine particles of Example 1, the same treatment as in Example 1 was performed except that the treatment with the fluorine-based silane coupling agent was not performed, and the surface-treated silica fine particles of Comparative Example 3 were obtained.

[Comparative Example 4]
In the surface treatment of the silica fine particles of Example 1, the same treatment as in Example 1 was performed except that the treatment with the fluorine-based silane coupling agent and the treatment with the methacrylic silane coupling agent were performed at room temperature. The surface-treated silica fine particles of Comparative Example 4 were obtained.

  The results of each evaluation for the antireflection films produced using the surface-treated silica fine particles of Examples 1 and 2 and Comparative Examples 1 to 4 are shown in Table 1 below.

  According to Table 1, it can be seen that the antireflection films of Examples 1 and 2 are both excellent in water repellency and oil repellency and excellent in scratch resistance.

The antireflection film obtained by the production method of the present invention can be applied to image display devices such as liquid crystal displays and plasma displays, and is excellent in antifouling property against water and / or oil and excellent in scratch resistance.

Claims (1)

A method for producing an antireflection film in which a low refractive index layer is formed as an outermost surface layer on a transparent plastic substrate film directly or via another layer,
In the low refractive index layer, silica fine particles having voids subjected to water repellent / oil repellent group introduction treatment and crosslinking group introduction treatment are included,
The silica fine particles having voids subjected to the introduction treatment of the water / oil repellency group and the introduction treatment of the crosslinking group are produced using the following steps 1) to 3) :
1) A step of increasing the activity of silanol groups on the surface of silica fine particles by removing impurity ions by pretreating silica fine particles having voids with an ion exchange resin;
2) a step of introducing a water- and oil-repellent group by adding a water- and oil-repellent treatment agent to silica fine particles having voids with enhanced activity of the silanol group, and heating;
3) A step of introducing a crosslinking group by adding a compound having a crosslinkable group to the silica fine particles having voids into which the water / oil repellent group has been introduced, and refluxing .
The amount of the water / oil repellent treatment agent applied to the silica fine particles is 3 to 25 parts by mass with respect to 100 parts by mass of the silica fine particles.
The processing amount of the compound having a crosslinkable group to the silica fine particles is 5 parts by mass to 25 parts by mass with respect to 100 parts by mass of the silica fine particles.
The total amount of the water / oil repellent treatment agent and the compound having a crosslinkable group is 8 to 30 parts by mass with respect to 100 parts by mass of the silica fine particles. .