JP2005213323A - Cured film in which dispersed fine particles are localized - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cured film which has both good surface hardness and inside flexibility and satisfies optical characteristics, flatness, abrasion resistance (scratch resistance), wear resistance, and adhesiveness to a substrate, when used as a coating film. <P>SOLUTION: This cured film prepared by coating an active energy ray-curable composition containing dispersed fine particles on a substrate and then curing the coating film is characterized in that the dispersed fine particles are localized on the surface of the cured film. It is preferable that an electrophoresis method is used as a means for localizing the dispersed fine particles. It is preferable that UV rays are used as the active energy rays, and it is preferable that the active energy ray-curable composition contains a radical-photopolymerizing component and an ionically photopolymerizing component. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cured film comprising an active energy ray-curable composition and dispersed fine particles, and more particularly to a cured film in the field of optical materials that requires a protective film having a remarkably large surface hardness as a cured film.

Improvement of mechanical strength as a protective film of coated cured film is required in various industrial fields, and in order to improve the friction resistance, scratch resistance, and abrasion resistance of polymer surfaces that are generally easily damaged. In addition, laminates of protective films with high hardness are used as chemical surface treatment methods such as coupling agent treatment, multi-layer polymerization treatment, and hard coat agent coating, and physical surface treatments include plasma treatment and mechanochemical treatment. Etc. are known.
Among these, the method of laminating a protective film with high hardness has various problems such as adhesion to the substrate, warpage and wrinkles.
Among the chemical treatment methods that are commonly used for surface treatment, silicone-based, fluorine-based, polyfunctional acrylic-based (polyol acrylate, polyester acrylate, urethane acrylate, epoxy acrylate, etc.) monomers, oligomers, and polymers A method of polymerizing and curing using a heat or active energy ray after coating a coating solution containing the above is known, and it is known that the friction resistance, scratch resistance, and wear resistance can be improved.

  In particular, in optical materials such as optical disks and optical films, the above-mentioned monomers are used as means for improving durability such as friction resistance and scratch resistance of the coating film surface without reducing optical characteristics, flatness, weather resistance, etc. A method of UV curing after applying an UV curable composition comprising an oligomer or the like is generally known. However, since it is an organic material, its durability is limited. On the other hand, as a means of improving durability by blending inorganic materials, an organic-inorganic hybrid film combining alkoxysilanes is known, but the problem of deformation due to shrinkage when the entire coating film is cured cannot be avoided. .

  Further, among physical treatment methods, a vapor deposition method using a CVD method is widely used as a method for forming a silicon or silicon compound thin film capable of obtaining a high breakdown voltage and high hardness. However, the CVD method is inferior in mass productivity because problems such as abnormal growth of a so-called flake film or damage to other structural films occur when the film forming rate is high. As a method with excellent mass productivity, a silicon or silicon compound thin film manufacturing method in which a material is evaporated using a high-density plasma gun and a silicon or silicon compound thin film is formed on a substrate has been proposed. Compared to the above, mass productivity is inferior, and in particular, application to optical materials requires design and control in consideration of warping of a film or a disk (see Patent Document 1).

  As a method for solving such a problem, water and / or metal alkoxide is polymerized by applying a homogeneous solution comprising an organic polymer, a metal alkoxide and a common solvent thereof onto an organic polymer or an inorganic substrate. A composite composed of an organic polymer component and a metal oxide component, which is obtained by holding the catalyst in an atmosphere containing air and then drying and heat-treating the metal in the depth direction from the surface of the composite. A component gradient composite of an organic polymer and a gold oxide component (see Patent Document 2) having a component gradient structure in which the content of the oxidized component in the complex continuously changes has been proposed.

  In addition, a wet gel prepared from an organic polymer having a metal alkoxy group by a sol-gel method, or the organic polymer dissolved in a solvent and a partial hydrolysis and polymerization of a metal oxide, a metal alkoxide compound, or a metal alkoxide compound. An organic-inorganic component gradient composite having a component gradient structure in which the concentration of the organic polymer component and / or the metal oxide component is continuously changed by contacting the condensate and diffusing each other or from one to the other. A manufacturing method for manufacturing a material (see Patent Document 3) has been proposed.

  Furthermore, a coating liquid comprising a mixture of an organic polymer compound having a metal-containing group capable of binding to a metal oxide by hydrolysis in the molecule and a metal compound capable of forming a metal oxide by hydrolysis is formed from an organic material. An organic-inorganic composite material containing a chemical bond between an organic polymer compound and a metal compound, which is produced by applying a coating on a substrate to form a coating film and then subjecting the material to heat drying. An organic-inorganic composite gradient material (see Patent Document 4) having a component gradient structure in which the content rate of the system compound continuously changes in the depth direction from the surface of the material has been proposed.

  Further, a solution obtained by adding a diluting solvent to an organic-inorganic composite obtained by polymerizing at least one organic compound having a functional group capable of forming an organic polymer chain in the presence of an inorganic polymer compound is used as a basis. It consists of a thin film formed by coating on the material, and due to the layer separation of the organic polymer component and the inorganic polymer component in the film thickness direction, the content of the inorganic component in the thin film becomes deep from the surface of the thin film. An organic-inorganic composite gradient film (see Patent Document 5) characterized by having a component gradient structure that continuously changes in the direction has been proposed. Although an inclined structure can be taken, the localization of inorganic components on the surface of the coating film is insufficient, and there is a limit to increasing the surface hardness of the coating film, and the processing time is significantly required.

Japanese Patent Laid-Open No. 11-6054 JP-A-8-283425 Japanese Unexamined Patent Publication No. 2000-248065 JP 2000-336281 A JP 2002-275284 A

  The purpose of the present invention is excellent in the flatness, friction resistance, scratch resistance, and abrasion resistance of the surface of the cured film, and also has excellent adhesion to the substrate because it retains the flexibility inside the cured film, and is inexpensive. Is to provide a cured film.

The present invention is a cured film obtained by applying an active energy ray-curable composition containing dispersed fine particles to a substrate to form a coated film, and then curing the coated film, wherein the dispersed fine particles are formed on the surface of the cured film. The present invention provides a cured film characterized by being localized in.
Furthermore, the present invention provides the cured film as described above, wherein the cured film obtained by curing the active energy ray-curable composition after coating is a protective film for coating an object to be coated which is a substrate.
Furthermore, the present invention provides a coating with a protective film, wherein at least a part of the surface is coated with the protective film described above.

  In the cured film of the present invention, since the dispersed fine particles in the cured film are localized on the surface of the cured film, the surface has high hardness only on the surface while maintaining flexibility as a cured film containing a resin. The whole material does not become brittle. As a result, when the cured film is used as a protective film, it is possible to achieve both high friction resistance and abrasion resistance and good adhesion to the substrate while maintaining the flatness of the surface.

The dispersed particles in the cured film are not particularly limited, such as crosslinked resin particles, metals, metal oxides, metal salts, etc., but considering the surface hardness and transparency when localized on the coating film surface, silica, alumina, ceria Metal oxides such as zirconia and titanium oxide, metal carbonates such as calcium carbonate and magnesium carbonate, silicates such as talc, calcium silicate and glass, metal titanates such as calcium titanate and barium titanate, etc. Metal oxide is particularly preferable.
In order to disperse the metal oxide, a generally known dispersion method, that is, a dispersant is selected according to the type of the metal oxide, and a known disperser is used together with other compositions of the coating liquid. Fine dispersion may be performed. In addition to these metal oxide dispersion methods, a metal alkoxide such as alkoxysilane may be gelled in another coating solution composition and then mixed to form a cured organic-inorganic hybrid film. In addition, a component gradient film of an inorganic component may be provided by means shown in advance in the patent literature.
When the dispersed fine particles are used as an optical material, the particle diameter of the dispersed fine particles is desirably an average particle diameter of not more than the wavelength of the use wavelength, preferably not more than a half wavelength, in order to ensure transparency.

  The method for localizing dispersed fine particles on the surface of a cured film is to apply a coating liquid comprising an active energy ray-curable composition containing the dispersed fine particles to a substrate, and apply the dispersed fine particles to the surface of the coating film before drying or curing the coating liquid. And it may be dried or solidified when it reaches the desired localized state. The degree of localization is not particularly limited as long as the desired properties of the cured film are satisfied. However, in order to obtain better hardness of the cured film surface, 90% by mass or more of the dispersed particles are preferably present within a depth of 1/5 or less of the thickness of the cured film from the cured film surface. More preferably, it exists in the depth of 1/10 or less of the film thickness of a cured film.

The moving method for localizing the dispersed particles can be performed by magnetophoresis in an applied magnetic field when the dispersed fine particles have magnetism. On the other hand, when the dispersed fine particles have a dielectric or surface charge, it can be carried out by electrophoresis. In particular, electrophoresis is preferable because many materials that do not have magnetism can be localized and used as dispersed fine particles.
When dispersed fine particles are dispersed in a coating solution, the particle surface forms an electric double layer and has a surface potential, but in order to impart a larger surface charge, electrophotographic liquid development A charge control agent such as that used in the agent may be used in combination. When the dispersed fine particles are positively charged, the particles are migrated using the negative electrode as the migration electrode. Conversely, when the dispersed particles are negatively charged, the particles are migrated using the positive electrode as the migration electrode.

  These charge control agents also function as dispersion stabilizers. However, these auxiliary agents can be selected from those usually used for liquid developers for electrostatic charge development for electrophotography. For example, naphthenic acid can be used. Cobalt, copper naphthenate, copper oleate, cobalt oleate, zirconium octylate, cobalt octylate, aluminum oxide acylate, aliphatic metal salts such as naphthenic acid, octenoic acid, oleic acid, stearic acid, sulfosuccinate Metal salt of acid ester, metal salt of oil-soluble sulfonic acid, metal salt of phosphate ester, metal salt of abietic acid or hydrogenated abitinic acid, Ca salt of alkylbenzene sulfonic acid, metal salt of aromatic carboxylic acid or sulfonic acid, polyoxyethyl Nonionic surfactants such as alkylamines, lecithin, flax Fats and oils such as oil, polyvinyl pyrrolidone, polyhydric alcohol organic acid ester, phosphate ester surfactant, sulfonic acid resin, amino acid derivative, copolymer containing maleic acid half amide component, quaternized amine polymer, etc. Are known.

When the dispersed fine particles are migrated using the electrophoresis method, the electric field in the depth direction of the coating necessary for the movement of the dispersed fine particles can be generated by placing the electrodes facing each other across the coating. . When the substrate is an insulator, the counter electrode is placed close to the substrate on the opposite side of the coating film across the substrate, and the substrate is sandwiched between the coating film and the electrode together with the migration electrode installed on the coating film. As a configuration, an electric field can be applied to the entire substrate. On the other hand, a conductive layer, for example, a transparent conductive layer such as ITO, may be provided between the substrate and the coating film to form a counter electrode. When the substrate is a metal, the substrate itself can be used as the counter electrode. With such an electrode arrangement, the distance between the opposing electrodes can be set narrow, so that the electric field strength can be increased.
In the case of roll coating, the migration electrode on the coating film surface side may also be used as the migration electrode. Also, if the electrical resistance of the coating solution is high, corona charging or ion flow charging is applied to the coating surface immediately after coating the coating solution instead of the migration electrode, and before drying or solidification, to apply a potential to the membrane surface. It can be used as an electrophoresis electrode. Rollless coating such as a spin coater, and curing of the coating solution while performing electrophoresis.If the coating solution has high electrical resistance, a device that performs the above-mentioned corona charging or ion flow charging after coating is used. Can be incorporated into coating equipment.
In particular, in the electrophoresis of dispersed fine particles, the dispersed fine particles are diffused by Brownian motion as soon as the electric field is removed. Therefore, it is necessary to cure the coating liquid immediately after migration or while performing migration. Therefore, particularly when the active energy ray is ultraviolet light, it is preferable that at least one of the electrodes is formed of an ultraviolet light transmissive material so that ultraviolet light can be irradiated while applying an electric field. For example, when a transparent conductive layer such as ITO is provided between the substrate and the coating film to form a counter electrode, the coating film can be cured by irradiating the substrate with ultraviolet rays if an ultraviolet transparent material is used. Is possible.
In electrophoresis, there are no particular limitations on the viscosity and electrical resistance value of the coating solution, and a combination of materials may be appropriately selected according to the electrophoresis conditions (voltage, time, distance between electrodes, etc.) to obtain optimum characteristics for electrophoresis.
At this time, in order to perform migration more effectively, it is desirable to apply a bias voltage to the counter electrode to increase the migration voltage.

  The localization of the dispersed fine particles on the surface of the cured film can be controlled by the migration speed and the migration time, and it is not necessary to move to the surface 100%, and the particle density in the cured film may have a gradient structure. good. A cured film having a particle density gradient structure can be obtained by curing the coating film while the localization of the dispersed fine particles on the surface of the uncured coating film is in progress. By adjusting the gradient structure of the particle density and adjusting the degree of localization of the dispersed particles, it becomes possible to reduce the mechanical and optical distortions associated with the heterogeneous two-layer structure, and to disperse the cured film. It becomes possible to produce a cured film having both the flexibility of the organic substance inside the film having a low particle concentration and the hardness of the inorganic substance in the surface portion having a high concentration of dispersed particles in a better state.

A method of coating the active energy ray-curable composition on the substrate and forming a coating film after the dispersed fine particles are localized can be carried out by irradiating and curing the active energy ray sensitive to the composition.
As active energy rays, particle rays such as electron beams, electromagnetic waves such as X-rays and ultraviolet rays can be used. However, ultraviolet rays are preferable in terms of handling and cost, and an ultraviolet curable composition for forming the cured film of the present invention. A thing is used suitably.

As a component for imparting ultraviolet curability of the ultraviolet curable composition, a photo radical polymerizable component or a photo ion polymerization component suitable for the purpose may be appropriately selected and used in combination. There are polyfunctional acrylic monomers and oligomers. Specifically, it is a polyfunctional oligomer having one or more (meth) acryloyl groups in one molecule, a polyfunctional monomer having a (meth) acryloyl group, or a 1-2 functional monomer having a (meth) acryloyl group.
Examples of the polyfunctional oligomer having a (meth) acryloyl group include polyester (meth) acrylate, polyurethane (meth) acrylate, and epoxy (meth) acrylate.

  Examples of polyfunctional monomers having a (meth) acryloyl group include trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, glycerol tri (meth) acrylate, and tris ((meth) acryloyloxyethyl) isocyanate. Nurate, Tris ((meth) acryloyloxypropyl) isocyanurate, Pentaerythritol tri (meth) acrylate, Pentaerythritol tetra (meth) acrylate, Dipentaerythritol tri (meth) acrylate, Dipentaerythritol tetra (meth) acrylate, Dipenta Erythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol tetra (meth) acrylate, tri Pentaerythritol penta (meth) acrylate, tripentaerythritol hexa (meth) acrylate, tripentaerythritol hepta (meth) acrylate, tripentaerythritol octa (meth) acrylate.

Examples of 1-2 functional monomers having a (meth) acryloyl group include cyclohexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, dicyclopentenyl (meth) acrylate, di Cyclopentenyloxyethyl (meth) acrylate, tricyclodecanyl (meth) acrylate, isobornyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxyethoxyethyl (meth) acrylate, ethoxyethoxyethyl ( Monofunctional (meth) acrylate monomers such as (meth) acrylate, phenoxyethyl (meth) acrylate, and phenoxypropyl (meth) acrylate; ethylene glycol di (meth) acrylate 1,6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, neopentyl glycol di (meth) Acrylate, tetraethylene glycol di (meth) acrylate, cyclohexane-1,4-dimethanol di (meth) acrylate, bisphenol A di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, trimethylolpropane di (meth) acrylate , Ethylene oxide modified bisphenol A di (meth) acrylate, neopentyl glycol modified trimethylolpropane di (meth) acrylate, bis- (2-methacryloyloxyethyl) phthale Difunctional (meth) acrylate monomers of bets, and the like.
Many of these ultraviolet curable components can also be used as a curable component when an active energy ray other than ultraviolet rays is used.

  In addition, as a component of the ultraviolet curable composition, if necessary, a protective film can be applied on a thin substrate such as a film, a high molecular weight oligomer component or an organic solvent for dilution is included in the composition. May be used in combination. It is preferable to use a photopolymerization initiator in combination.

  Examples of photopolymerization initiators include benzoin monomethyl ether, benzoin isopropyl ether, benzyl dimethyl ketal, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, methyl phenyl glyoxylate, ethyl phenyl glyoxylate, 2- Examples include acylphosphine oxides such as hydroxy-2-methyl-1-phenylpropan-1-one, 2,4,6-trimethylbenzoylphenylphosphine oxide, and the like. Among these, 1-hydroxycyclohexyl phenyl ketone, methylphenyl glyoxylate, ethylphenyl glyoxylate, and 2-hydroxy-2-methyl-1-phenylpropan-1-one are from the viewpoint of transparency and curability. Is particularly preferred.

In addition, when an ultraviolet curable composition is applied to a substrate having a low energy surface, a surfactant or a coating additive can be added in order to obtain a cured film having good coating quality. For example, wetting and curing with a substrate by adding a fluorine-based nonionic surfactant, a modified silicone-based surfactant, a vinyl-based or acrylic polymer coating additive, etc., alone or in combination to an ultraviolet curable composition. Improves subsequent surface smoothness. Addition of an antistatic agent can suppress dust adsorption.
Further, as an adhesion enhancer with metal, for example, (meth) acrylate having a carboxyl group such as ethylene oxide modified succinic acid (meth) acrylate, ethylene oxide modified phthalic acid (meth) acrylate, or ethylene oxide modified phosphoric acid (meth) acrylate (Meth) acrylate having a phosphoric acid group in the molecule such as ethylene oxide-modified phosphoric acid di (meth) acrylate and caprolactone-modified phosphoric acid group di (meth) acrylate can also be added.
In addition, various durability improvers such as ultraviolet absorbers, light stabilizers and antioxidants, and coating properties of ultraviolet curable compositions may be changed, or inorganic or organic materials may be used to form irregularities on the surface of the cured film. Fillers and coloring agents can be added for coloring.

  The cured film of the present invention exhibits an excellent function when used in the field of optical materials, particularly as a protective surface of an object to be coated. Not only that, but also a printing plate or optical disk using a compound curable by active energy rays It can be used as a technique for improving the wear resistance, scratch resistance and hardness of the surface of the cured film over a wide variety of application fields where the surface hardness of the cured film is important, such as a substrate.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples. First, a solventless ultraviolet curable composition having the composition shown in Table 1 was prepared.

M-315: tris (acryloyloxyethyl) isocyanurate TMP3A: trimethylolpropane triacrylate BP: benzophenone DMAEA: N, N-dimethylaminoethylacrylamide FZ-2188: polyether-modified silicone oil hydrophobic silica manufactured by Nihon Unicar Company, Japan Aerosil R972 (methacrylic silane-treated silica) manufactured by Aerosil

(Example 1 and Comparative Example 1)
An ultraviolet curable composition having the composition of Example 1 in Table 1 or Comparative Example 1 was spin-coated on a substrate so as to have a film thickness of about 5 μm (see FIG. 1), and a voltage of 40 KV was applied to the corona discharge device. Then, the surface of the coating film was positively charged, and hydrophobic silica was electrophoresed toward the surface of the coating film by electrophoresis (see FIG. 2). The conveyor speed was adjusted by a conveyor type ultraviolet curing device (input power 120 W / cm) so that one pass was 0.75 J / cm ^2, and the coating film was cured (see FIG. 3). The flatness and smoothness of the coating surface were good. Thereafter, the surface was rubbed with a Kim wipe impregnated with methanol, and the coating film was confirmed to be cured by the presence or absence of whitening of the surface. In the table, OK represents a case where the surface of the cured film was not affected by the solvent and did not cause whitening, and NG represents a case where whitening was observed.

(Example 2 and Comparative Example 2)
A coating material having the composition of Example 2 in Table 1 or Comparative Example 2 was applied on the substrate so that the film thickness was about 10 μm. In Example 2, a positive voltage of 1 KV was applied to the coating roll, and a comparative example was applied. In No. 2, no voltage is applied to the coating roll, and the conveyor speed is adjusted so that one pass is 0.75 J / cm 2 with a conveyor type ultraviolet curing device (input power 120 W / cm) installed immediately after the coating roll. The film was cured (see FIG. 4). The flatness and smoothness of the cured film surface were good. Thereafter, the surface was rubbed with a Kim wipe impregnated with methanol, and the coating film was confirmed to be cured by the presence or absence of whitening of the surface. In the table, OK represents a case where the surface of the cured film was not affected by the solvent and did not cause whitening, and NG represents a case where whitening was observed.

(Evaluation of surface hardness)
In the same manner as above (however, the curing condition of the paint F is 1.0 J / cm @ 2 for one pass), and a cured coating film is prepared on a transparent glass substrate. The film hardness was evaluated.

(Evaluation of adhesion to cyclic olefin film)
The UV curable composition was applied on an “Arton” film (188 μm thick) manufactured by JSR Co., Ltd. and cured, and the adhesion of the cured film was evaluated. Evaluation of adhesiveness was performed by the crosscut-cello tape (registered trademark) peel test method in accordance with JIS K-5400. In the table, OK represents a case where peeling from the film of the cured coating film was not observed, and NG represents a case where peeling was observed.

  The test results are shown in Table 2.

  As is apparent from Table 2, Examples 1 and 2 achieve higher pencil hardness without impairing adhesiveness and curability as compared with Comparative Examples 1 and 2, respectively.

It is explanatory drawing which showed the example (Example 1) of the manufacturing method of the cured film of this invention, Comprising: It is a figure which shows the state after the coating to the base | substrate of the coating liquid which consists of an ultraviolet curable composition. It is explanatory drawing which showed the example (Example 1) of the manufacturing method of the cured film of this invention, Comprising: It is a figure which shows the process of the dispersion | distribution microparticles | fine-particles by electrophoresis using a corona charge. It is explanatory drawing which showed the example (Example 1) of the manufacturing method of the cured film of this invention, Comprising: It is a figure which shows the process of ultraviolet curing. It is explanatory drawing which showed the example (Example 2) of the manufacturing method of the cured film of this invention, Comprising: (1) Coating to the base | substrate of a coating liquid, (2) Electrophoresis, (3) Process which consists of ultraviolet curing It is the figure shown through.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Uncured coating film 2 Substrate 3 Corona charging electrode 4 Ultraviolet ray 5 Coating roll / electrophoresis electrode 6 Support roll / counter electrode 7 Dispersed particle localized coating film (cured)
8 Coating direction

Claims (7)

A cured film formed by applying an active energy ray-curable composition containing dispersed fine particles to a substrate to form a coating film, and then curing the coating film, wherein the dispersed fine particles are localized on the surface of the cured film. A cured film characterized by having The cured film according to claim 1, wherein the hardness of the surface of the cured film where the dispersed fine particles are localized is higher than the hardness inside the cured film where the dispersed particles are not localized. The cured film according to claim 1, wherein the dispersed fine particles are a metal oxide. The cured film moves the dispersed fine particles in the active energy ray-curable composition in the surface direction of the coating film after application of the composition, and then activates the active energy ray to which the composition is sensitive to the coating film. The cured film according to claim 1, which is produced by irradiation and curing. The cured film according to any one of claims 1 to 4, wherein the dispersed fine particles are moved and localized on the surface of the coating film by electrophoresis. The cured film according to any one of claims 1 to 5, wherein the cured film obtained by curing the active energy ray-curable composition after coating is a protective film that covers an object to be coated that is a substrate. A covering with a protective film, wherein at least a part of the surface is covered with the protective film according to claim 6.

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