JP2012215705A - Method for manufacturing hard coat film and hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a hard coat film, which suppresses occurrence of curling without impairing surface hardness of the film, and a hard coat film obtained by the method.SOLUTION: A method for manufacturing a hard coat film includes a step for forming a hard coat layer by polymerizing a photopolymerizable compound by photoirradiation after applying a composition containing the photopolymerizable compound on a base material. In the step for forming the hard coat layer, a film surface temperature is controlled to be 20-30°C during the photoirradiation, the photoirradiation is performed twice or more, and non-irradiation times each of which has 10-60 seconds are set between each photoirradiation time.

Description

  The present invention relates to a method for producing a hard coat film and a hard coat film.

  In recent years, liquid crystal display devices (LCD) have increased in screen size, and for example, liquid crystal display devices having an optical film such as an antireflection film or a light diffusion sheet are increasing. For example, the antireflection film is used in various image display devices such as a liquid crystal display device (LCD), a plasma display panel (PDP), an electroluminescence display (ELD), and a cathode ray tube display device (CRT). Is disposed on the surface of the display in order to prevent a decrease in contrast due to the reflection of the image. The light diffusion sheet is used on the backlight side of the liquid crystal display device.

The optical film is usually produced by laminating a light diffusing (hard coat) layer or a high refractive index layer and a low refractive index layer on a transparent support.
Since an optical film is used on the outermost surface of a display, various film strengths such as scratch resistance against fine scratches and film hardness that can withstand pressure when written with a writing instrument are required.
In order to meet these requirements, a method of laminating a hard layer on the surface, a method of forming a layer containing an organosilane compound, a method of increasing the thickness of the layer to be laminated, and the like have been performed.
As a method for increasing such film strength, for example, in Patent Document 1, from the viewpoint of scratch resistance, in the method for producing an optical film, in a curing step after application and drying, a heat treatment and a light irradiation step are performed. The method of performing this several times sequentially or simultaneously is described.
In addition, from the viewpoint of suppression of molding defects such as high hardness, cracks, and cracks, a method of photocuring by changing light irradiation in multiple stages is known (for example, see Patent Documents 2 and 3). For example, Patent Document 2 describes a method of forming a cured coating film by irradiating ultraviolet rays in multiple stages on the surface of a plastic molded product.
On the other hand, in order to make the surface of the display film thinner, it is required to make the support thinner.
When the film strength is imparted or the support is thinned, the curl becomes large, and there is a problem that the handleability in the production and processing of the surface film becomes difficult.
Further, in the development of optical films, when curling is suppressed, there is a problem that the film surface hardness decreases, and the development of an optical film that achieves both surface hardness and curling suppression has been desired.

JP 2007-256925 A JP-A-61-238 JP-A-3-90320

  An object of the present invention is to provide a method for producing a hard coat film in which the occurrence of curling is suppressed without impairing the surface hardness of the film, and a hard coat film obtained thereby, in view of the above-mentioned problems of the prior art. It is in.

The above object of the present invention is achieved by the following means.
[1]
A method for producing a hard coat film, comprising: applying a composition containing a photopolymerizable compound on a substrate; and then polymerizing the photopolymerizable compound by light irradiation to form a hard coat layer. In the step of forming the hard coat layer, the film surface temperature when performing the light irradiation is controlled to 20 ° C. to 30 ° C., the light irradiation is performed twice or more, and 10 seconds to 60 seconds are not applied between each light irradiation. A method for producing a hard coat film, wherein an irradiation time is provided.
[2]
The method for producing a hard coat film according to [1], wherein the first unirradiated time is provided after 30% to 50% of the hard coat layer is cured by polymerization of the polymerizable compound.
[3]
The manufacturing method of the hard coat film as described in [1] or [2] whose irradiation time in the 1st light irradiation is 0.01 to 1 second.
[4]
The hard according to any one of [1] to [3], wherein the light illuminance after curing at least 50% as a curing rate of the hard coat layer by polymerization of the photopolymerizable compound is 100 mW / cm ² or less. A method for producing a coated film.
[5]
The method for producing a hard coat film according to any one of [1] to [4], wherein the unirradiated time is provided once or twice in the step of forming the hard coat layer.
[6]
The method for producing a hard coat film according to any one of [1] to [5], wherein the film surface temperature when performing the light irradiation is controlled by a temperature-controlled wind and a roller.
[7]
The hard coat film manufactured by the manufacturing method of any one of [1]-[6].

The method for producing a hard coat film of the present invention can produce a hard coat film in which the occurrence of curling is suppressed without impairing the surface hardness of the film.
Moreover, the hard coat film of the present invention obtained by the above production method can achieve both high surface hardness and curl generation suppression.

  In this specification, when a numerical value represents a physical property value, a characteristic value, or the like, the description “(numerical value 1) to (numerical value 2)” represents the meaning of “numerical value 1 or more to numerical value 2 or less”. In the present specification, the description “(meth) acrylate” means “at least one of acrylate and methacrylate”. The same applies to “(meth) acrylic acid” and the like.

  In the method for producing a hard coat film of the present invention, a composition containing a photopolymerizable compound (hereinafter also simply referred to as “curable compound”) is applied on a substrate, and then the photopolymerizable compound is irradiated with light. Is a method for producing a hard coat film having a step of forming a hard coat layer, and in the step of forming the hard coat layer, the film surface temperature when performing the light irradiation is 20 ° C. to 30 ° C. Control, perform two or more times of light irradiation, and provide 10-60 seconds of non-irradiation time between each light irradiation.

The inventor of the present invention is that, as the polymerization reaction of the photopolymerizable compound (curable compound) proceeds during the hard coat layer formation and the hard coat layer is cured, the shrinkage stress increases in the layer, and is cured to some extent ( It has been found that when the polymerization is advanced, the occurrence of curling abruptly increases due to the shrinkage stress, and when the curing (polymerization) is continued as it is, the generated curl cannot be restored. On the other hand, even if the shrinkage stress is increased inside the hard coat layer as the hardening progresses, the shrinkage stress can be relieved as described below, and curling can be suppressed. I find that there is. The present invention has been made based on this finding.
The reason why the hard coat film production method of the present invention suppresses the occurrence of curling is not clear, but is estimated as follows.
By providing a non-irradiation time during light irradiation, curling can be suppressed by relaxing the shrinkage stress caused by the hardening of the hard coat layer by thermal diffusion of the polymerization reaction product. It is presumed that a hard coat layer can be formed without curling by repeating curing by irradiation and relaxation of the shrinkage stress by non-irradiation.

[Light irradiation]
After application, when thermal polymerization (thermosetting) is performed, the resin is cured in a thermally expanded state, and heat shrinkage occurs when the temperature returns to room temperature after curing, generating a large shrinkage stress and causing curling.
On the other hand, the light irradiation in the method for producing a hard coat film of the present invention can be performed by light irradiation, electron beam irradiation, or the like without performing thermal polymerization (thermosetting) after the coating, and the polymerizable compound. Can be polymerized or crosslinked to form a hard coat layer, and shrinkage stress and curling can be suppressed.
In the method for producing a hard coat film of the present invention, from the viewpoint of alleviating the shrinkage stress caused by the progress of curing, the light irradiation in the step of forming the hard coat layer is performed twice or three times, and each light irradiation is performed. It is preferable that the non-irradiation time provided between them is 1 or 2 times.
In the present invention, the non-irradiation time refers to a time during which light is not substantially irradiated, for example, an environment with an illuminance of 1 mW / cm ² or less, preferably 0.2 mW / cm ² or less. .
Preferably there is no particular limitation on the light intensity in the first light irradiation (first irradiation) is 10 to 1,000 / cm ^2, and more preferably 20 to 500 mW / cm ^2.
Although there is no restriction | limiting in particular as irradiation time in the 1st light irradiation, It is preferable that it is 0.01 to 1 second from a viewpoint of achieving the following hardening rate 30 to 50%, and 0.02 to 0.5 second. It is more preferable that
In the method for producing a hard coat film of the present invention, the first non-irradiation time is preferably provided after being cured by 30% to 50% as a curing rate of the hard coat layer by polymerization of the polymerizable compound, It is more preferable to provide after 50% curing. When the first non-irradiation time is set, the productivity is good because the curing rate is 30% or more, and the shrinkage stress generated in the hard coat layer can be relaxed when the curing rate is 50% or less. Curling can be suppressed.
In the method for producing a hard coat film of the present invention, for example, after curing at 30% to 50% as a curing rate of the hard coat layer by polymerization of the photopolymerizable compound by light irradiation such as the first time, It is more preferable to provide the non-irradiation time of 10 seconds to 60 seconds from the viewpoint of suppressing curling by relaxing the generated shrinkage stress, and considering not only the viewpoint of curling suppression but also productivity, More preferably, the unirradiated time of 20 seconds is provided.
Each non-irradiation time after the second time is 10 to 60 seconds, and preferably 10 to 20 seconds.
In the method for producing a hard coat film of the present invention, from the viewpoint of further curling suppression, the light illuminance after the hard coat layer is cured by 50% or more by polymerization of the photopolymerizable compound (for example, second time, 3 The light irradiation such as the second time is preferably 100 mW / cm ² or less, and more preferably ²⁰ to 50 mW / cm ² .
Although there is no restriction | limiting in particular as each irradiation time in each light irradiation after the 2nd time, it is preferable that it is 0.1-20 seconds, and it is more preferable that it is 1-10 seconds.
In the case of ultraviolet irradiation, ultraviolet rays emitted from light such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, a metal halide lamp, etc. can be used.
Curing with ultraviolet rays is preferably performed by nitrogen purge or the like with an oxygen concentration of 4% by volume or less, more preferably 2% by volume or less, and most preferably 0.5% by volume or less. The film surface temperature is controlled to 20 ° C. to 30 ° C. from the viewpoint of suppressing the shrinkage stress and curling.
In the present invention, the rise in the film surface temperature due to the radiant heat of the light source can be suppressed by using a temperature-adjusted wind and roller. UV irradiation dose is preferably ^{20~600mJ / cm 2, 50~300mJ / cm} 2 is more preferable.
In the method for producing a hard coat film of the present invention, the hard coat layer is cured by curing at 70% or more, preferably 80% or more, more preferably 90% or more as a curing rate of the hard coat layer by polymerization of the photopolymerizable compound. Formation can be achieved.

[Base material]
As a substrate in the method for producing a hard coat film of the present invention, it is preferable to use a plastic film, and it is more preferable to use a transparent 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 Film), polyamide, polycarbonate, polyester (eg, polyethylene terephthalate, polyethylene). Naphthalate), polystyrene, polyolefin, norbornene 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.
[Application method]
Although there is no restriction | limiting in particular as a coating system in the manufacturing method of the hard coat film of this invention, The composition for coating (coating liquid) for forming a hard-coat layer is a bar coating method, a dip coating method, an air knife coating method, It is preferably coated on a substrate by curtain coating, roller coating, gravure coating or die coating, and then heated and dried, more preferably by bar coating, micro gravure coating or die coating. It is particularly preferable to apply by a coating method.
Thereafter, the photopolymerizable compound that forms the hard coat layer can be polymerized and cured by light irradiation. Thereby, a hard coat layer is formed. If necessary, the hard coat layer may be a plurality of layers. Thus, the hard coat film in the present invention is obtained.
Similarly, a coating solution for forming a low refractive index layer is applied on the functional layer, and is irradiated with light or heated (irradiated with ionizing radiation such as ultraviolet rays, preferably cured by irradiation with ionizing radiation under heating. And) a low refractive index layer may be formed.

[Composition forming a hard coat layer]
The composition for forming the hard coat layer in the method for producing a hard coat film of the present invention, that is, the coating composition or the coating liquid is mainly composed of the photopolymerizable compound such as a curable monomer, oligomer or polymer as a matrix-forming binder. contains. In addition, it may contain a photopolymerization initiator and an organic solvent, and if necessary, translucent particles having the specific particle size ratio, additives for increasing film hardness, curl reduction, refractive index adjustment, etc. May contain an inorganic fine particle filler, a coating aid, and the like.

  Here, the binder refers to a film component excluding translucent particles, the photopolymerizable compound and a photocurable resin obtained by polymerization thereof, a polymer compound described later, an organosilicon compound, and a surface activity. Including agents.

[Polymerizable compound]
In the present invention, one or two or more arbitrary acrylate compounds can be used as the photopolymerizable compound (curable compound). Among them, it is possible to suitably use an acrylate-based compound that has three or more (meth) acryloyl groups in one molecule and forms a hardened cured material widely used in the industry. Examples of such compounds include esters of polyhydric alcohol and (meth) acrylic acid {for example, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO-modified tris. Methylolpropane tri (meth) acrylate, PO-modified trimethylolpropane tri (meth) acrylate, EO-modified tri (meth) acrylate phosphate, trimethylolethane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol Tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate DOO, 1,2,3-cyclohexane tetramethacrylate, polyurethane polyacrylate, polyester polyacrylate and caprolactone-modified tris (acryloyloxyethyl) isocyanurate.

  As specific compounds of polyfunctional acrylate compounds having three or more (meth) acryloyl groups, KAYARAD DPHA, DPHA-2C, PET-30, TMPTA, and TPA-320 manufactured by Nippon Kayaku Co., Ltd. , TPA-330, RP-1040, T-1420, D-310, DPCA-20, DPCA-30, DPCA-60, GPO-303, V made by Osaka Organic Chemical Industry Co., Ltd. An esterified product of a polyol such as # 400, V # 36095D and (meth) acrylic acid can be used. Also, purple light UV-1400B, UV-1700B, UV-6300B, UV-7550B, UV-7600B, UV-7605B, UV-7610B, UV-7620EA, UV-7630B, UV-7630B, UV-7640B. UV-6630B, UV-7000B, UV-7510B, UV-7461TE, UV-3000B, UV-3200B, UV-3210EA, UV-3210EA, UV-3310EA, UV-3310B, UV-3500BA , UV-3520TL, UV-3700B, UV-6100B, UV-6640B, UV-2000B, UV-2010B, UV-2250EA, UV-2750B (manufactured by Nippon Synthetic Chemical Co., Ltd.), UL-503LN (manufactured by Kyoeisha Chemical Co., Ltd.), Unidic 17-80 17-813, V-4030, V-4000BA (Dainippon Ink Chemical Co., Ltd.), EB-1290K, EB-220, EB-5129, EB-1830, EB-4358 (Daicel UCB ( Ltd.), High Corp AU-2010, AU-2020 (manufactured by Tokushi Co., Ltd.), Aronix M-1960 (manufactured by Toagosei Co., Ltd.), Art Resin UN-3320HA, UN-3320HC, UN-3320HS, UN Trifunctional urethane acrylate compounds such as -904, HDP-4T, Aronix M-8100, M-8030, M-9050 (manufactured by Toagosei Co., Ltd., KBM-8307 (manufactured by Daicel Cytec Co., Ltd.)) The above polyester compounds and the like can also be suitably used.

  Furthermore, as the photopolymerizable compound in the present invention, a resin having three or more (meth) acryloyl groups, for example, a relatively low molecular weight polyester resin, a polyether resin, an acrylic resin, an epoxy resin, a urethane resin, an alkyd resin, a spiro resin. Examples also include oligomers or prepolymers such as polyfunctional compounds such as acetal resins, polybutadiene resins, polythiol polyene resins, and polyhydric alcohols.

  The polymerizable compound (for example, a trifunctional or higher polyfunctional (meth) acrylate compound) used in the present invention is contained in the composition for forming the hard coat layer so as to be 40 to 99% by mass with respect to the total amount of the binder. Preferably, it is contained in the composition for forming the hard coat layer so as to be 50 to 98% by mass, and is contained in the composition for forming the hard coat layer so as to be 60 to 98% by mass. More preferably.

[Photopolymerization initiator]
The photopolymerization initiator used in the present invention is a compound that generates a radical capable of initiating a radical polymerization reaction upon irradiation with ionizing radiation. “Latest UV Curing Technology” (p.159, publisher; Kazuhiro Takasawa, published) (Corporate Information Association, published in 1991), Ciba Specialty Chemicals catalog, JP-A-2001-139663, JP-A-5-83588, JP-A-5-83588, JP-A No. 1-304453, U.S. Pat. No. 3,479,185, JP-A-5-239015, JP-A-8-134404, JP-A-11-217518, JP-A-2002-116539, JP-A-2002-116539, etc. Various known photopolymerization initiators described in the above publication can be used. Among them, a photoinitiator having a photosensitivity wavelength of 300 nm to 430 nm and having a high photoinitiating ability is preferably used because the photosensitivity wavelength is matched with a light source such as a high-pressure mercury lamp or a metal halide lamp and exhibits high sensitivity. From the viewpoint of coloring the film, those having a photosensitive wavelength of 300 nm to 380 nm are more preferable.

  The photopolymerization initiator is preferably used in correspondence with the polymerizable compound, and is preferably used in a range of 0.1 to 15 parts by mass with respect to 100 parts by mass of the polymerizable compound as a total amount of the polymerization initiator. The range of 1-10 mass parts is more preferable. Specific photopolymerization initiators are listed below, but are not limited thereto.

  Among the above compounds, the trihalomethyl-s-triazine initiators described in C-1 to C-6, the acylphosphone initiators described in C-13, C-14, C-16, and C-17, An α-cleavage type initiator of C-18, C-23, C-22, and C-29 and a ketoxime initiator of C-26 and C-28 are preferable because of high sensitivity and little coloring.

(Polymer compound)
The composition forming the hard coat layer according to the present invention may contain a polymer compound. By containing a polymer compound, curing shrinkage can be reduced, and the viscosity of the coating solution can be adjusted more favorably with respect to the dispersion stability (cohesiveness) of the resin particles, and further solidified during the drying process. It is preferable because the agglomeration behavior of the resin particles can be changed by controlling the polarity of the product, and drying unevenness in the drying process can be reduced.

  The polymer compound has already formed a polymer when it is contained in the composition for forming the hard coat layer. Examples of the polymer compound include cellulose esters (for example, cellulose triacetate, cellulose diacetate, cellulose Pionate, cellulose acetate propionate, cellulose acetate butyrate, cellulose nitrate, etc.), urethanes, polyesters, (meth) acrylic acid esters (for example, methyl methacrylate / methyl (meth) acrylate copolymer, Methyl methacrylate / ethyl (meth) acrylate copolymer, methyl methacrylate / butyl (meth) acrylate copolymer, methyl methacrylate / styrene copolymer, methyl methacrylate / (meth) acrylic acid copolymer, Polymethyl methacrylate, etc.) Resins such as styrene are preferably used.

From the viewpoint of the effect on curing shrinkage and the effect of increasing the viscosity of the composition forming the hard coat layer, the polymer compound is preferably 10 to 60% by mass with respect to the total binder contained in the layer containing the polymer compound, More preferably, it contains in the range of 20-50 mass%.
Further, the molecular weight of the polymer compound is preferably from 30,000 to 400,000 in terms of mass average, more preferably from 50,000 to 300,000, and even more preferably from 50,000 to 200,000.

  The refractive index of the binder is preferably 1.40 to 2.00, more preferably 1.45 to 1.90, still more preferably 1.48 to 1.85, and particularly preferably as the whole matrix. Is 1.51-1.80. The refractive index of the binder is a value measured by removing resin particles from the components of the hard coat layer.

  It is preferable to contain the binder of a hard-coat layer in 20-95 mass% with respect to the solid content of the composition which forms a hard-coat layer.

(Translucent particles)
The light diffusible hard coat layer can be formed by adding translucent particles to the composition forming the hard coat layer in the present invention.
The composition forming the hard coat layer in the present invention may contain translucent particles having an average particle size of 0.2 to 0.8 times the thickness of the obtained hard coat layer. preferable. A more preferable average particle diameter is 0.3 to 0.8 times, more preferably 0.4 to 0.7 times the thickness of the hard coat layer. When the average particle diameter is in the above range, the screen is excellent in blackening and has a moderate anti-glare property, and there is little roughness, and when viewing a high-definition display caused by surface irregularities called glare Can be reduced.

In order to effectively exhibit the light diffusing effect, it is preferable that the translucent particles have the above average particle diameter range and adjust the difference in refractive index with the binder described above. Specifically, the refractive index difference between the translucent particles and the binder is 0.02 or more, more preferably 0.03 or more and 0.25 or less, and particularly preferably 0.04 or more and 0.2 or less.
Further, the resin particles are preferably those in which the crosslinking agent is contained in an amount of 3 mol% or more with respect to all monomers before the particles are synthesized.
The content of the translucent particles with respect to the binder is preferably 2 to 40% by mass in the total solid content of the composition forming the hard coat layer, and particularly preferably 4 to 25% by mass.
The coating amount of the light-transmitting particle is preferably ^{10mg / m 2 ~10000mg / m 2} , more preferably ^{50mg / m 2 ~4000mg / m 2} .

  Specific examples of the translucent particles according to the present invention include resin particles such as crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles, crosslinked polystyrene particles, and crosslinked methyl methacrylate-methyl acrylate. Preferred examples include polymer particles, crosslinked acrylate-styrene copolymer particles, melamine resin particles, benzoguanamine resin particles, and polycarbonate particles. Furthermore, so-called surface-modified particles in which compounds containing fluorine atoms, silicon atoms, carboxyl groups, hydroxyl groups, amino groups, sulfonic acid groups, phosphoric acid groups and the like are chemically bonded to the surface of these resin particles are also preferred. Of these, crosslinked styrene particles, crosslinked polymethyl methacrylate particles, crosslinked methyl methacrylate-styrene copolymer particles, and the like are preferable.

As the shape of the resin particles, either a true sphere or an indefinite shape can be used. The particle size distribution is preferably monodisperse particles because of the haze value, controllability of diffusibility, and uniformity of the coated surface. 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, more preferably 0.1% or less of the total number of particles. Yes, more preferably 0.01% or less. Particles having such a particle size distribution are obtained by classification after a normal synthesis reaction, and particles having a more preferable distribution can be obtained by increasing the number of classifications or increasing the degree of classification.
Specific examples of the inorganic particles of the light transmissive particles, such as silica particles, hollow silica particles, alumina particles, TiO ₂ particles, Mg0 ₂ particles, Sr0 ₂ particles, BaO ₂ particles, SrSO ₄ particles, SnO ₂ particles, ZnO ₂ Examples thereof include metal oxide particles such as particles. These are also preferably secondary particles or amorphous secondary particles in order to suppress particle settling during production.

  The particle size distribution of the particles is measured by a Coulter counter method, and the measured distribution is converted into a particle number distribution. The average particle size is calculated from the obtained particle distribution.

(Inorganic filler)
In the composition forming the hard coat layer in the present invention, in order to increase the hardness of the layer, decrease the curing shrinkage, and further increase the refractive index, in addition to the above-described translucent particles, the inorganic filler is adjusted to adjust the refractive index, It can also be contained for the purpose of adjusting the film strength.
The content of the inorganic filler is preferably 10% by mass or more, preferably 15% by mass to 80% by mass, more preferably 20% by mass to 70% by mass, based on the total solid content of the composition forming the hard coat layer.
The inorganic filler is made of an oxide of at least one metal selected from titanium, zirconium, aluminum, indium, zinc, tin, and antimony, and the average primary particle diameter is generally 0.2 μm or less, preferably It is also preferable to contain a fine inorganic filler of 0.1 μm or less, more preferably 0.06 μm or less.

  Conversely, in a light diffusible hard coat layer using resin particles having a high refractive index, it is also preferable to lower the refractive index of the binder in order to increase the difference in refractive index from the particles. For this purpose, silica fine particles, hollow silica fine particles and the like can be used as the inorganic filler. The preferred particle size is the same as that of the above-mentioned high refractive index fine inorganic filler.

Specific examples of these finely divided inorganic _{filler, TiO 2, ZrO 2, Al} 2 O 3, In 2 O 3, ZnO, SnO 2, Sb 2 O 3, ITO ( indium oxide doped with Sn), SiO ₂ or the like Can be mentioned. TiO ₂ and ZrO ₂ are particularly preferable in terms 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 fine inorganic filler does not scatter because the particle size is sufficiently shorter than the wavelength of light, and the dispersion in which the filler is dispersed in the binder polymer has the property of an optically uniform substance.

(Organic solvent)
The coating composition for forming the hard coat layer preferably contains at least one organic solvent.
As an organic solvent, for example, in an alcohol system, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, isoamyl alcohol, 1-pentanol, n-hexanol, methyl amyl alcohol In the ketone system, methyl isobutyl ketone, methyl ethyl ketone, diethyl ketone, acetone, cyclohexanone, diacetone alcohol, etc., in the ester system, methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, isobutyl acetate, n-butyl acetate, Isoamyl acetate, n-amyl acetate, methyl propionate, ethyl propionate, methyl butyrate, ethyl butyrate, methyl acetate, methyl lactate, ethyl lactate, ether, acetal, 1,4 dioxane, te In hydrocarbons such as lahydrofuran, 2-methylfuran, tetrahydropyran, diethyl acetal, etc., hexane, heptane, octane, isooctane, ligroin, cyclohexane, methylcyclohexane, toluene, xylene, ethylbenzene, styrene, divinylbenzene, etc., halogen hydrocarbons In, carbon tetrachloride, chloroform, methylene chloride, ethylene chloride, 1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene, tetrachloroethylene, 1,1,1,2-tetrachloroethane In the case of polyhydric alcohols and derivatives thereof, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoacetate, diethylene glycol, In fatty acid systems such as lenglycol, dipropylene glycol, butanediol, hexylene glycol, 1,5-pentadiol, glycerin monoacetate, glycerin ethers, 1,2,6-hexanetriol, formic acid, acetic acid, propionic acid, In the case of nitrogen compounds such as butyric acid, isobutyric acid, isovaleric acid, and lactic acid, formamide, N, N-dimethylformamide, acetamide, acetonitrile, etc., and in the case of sulfur compounds, dimethyl sulfoxide and the like can be mentioned.
Among these, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, acetone, toluene, xylene, ethyl acetate, 1-pentanol and the like are particularly preferable. For the purpose of controlling aggregation, an alcohol or a polyhydric alcohol solvent is appropriately mixed. It may be used.
These organic solvents may be used alone or in combination, and the coating composition preferably contains 40% by mass to 98% by mass, and preferably 60% by mass to 97% by mass, as the total amount of the organic solvent. More preferably, it is most preferable to contain 70 mass%-95 mass%.

(Surfactant)
The composition for forming the hard coat layer in the present invention is a fluorine-based or silicone-based surfactant, or both, particularly in order to ensure surface uniformity such as coating unevenness, drying unevenness, and point defects. Is preferably contained in the coating composition for the hard coat layer. In particular, a fluorine-based surfactant is preferably used because an effect of improving surface defects such as coating unevenness, drying unevenness, and point defects of the hard coat film of the present invention appears in a smaller addition amount.
The purpose is to increase productivity by giving high-speed coating suitability while improving surface uniformity.
Preferable examples of the fluorosurfactant include a copolymer (so-called fluoropolymer) containing any fluoroaliphatic group.

The thickness of the hard coat layer in the hard coat film obtained by the production method of the present invention is preferably 0.03 to 0.20 times the thickness of the substrate, and 0.05 to 0.17 times. Is more preferable, and 0.07 to 0.15 times is more preferable. When the thickness is within this range, the film hardness is excellent, there are no defects such as curl, haze value, and glare, and the adjustment of anti-glare property and darkness is easy. For example, when the thickness of the base material is 80 μm, the thickness of the hard coat layer is preferably 2.4 μm to 16 μm, and when the thickness of the base material is 40 μm, it is preferably 1.2 μm to 8 μm.
The strength of the hard coat layer is preferably 3H or more in a pencil hardness test according to JIS K5400.

  As described above, the hard coat layer in the hard coat film obtained by the production method of the present invention may or may not contain translucent particles. It may be a hard coat layer having an antiglare property) or a hard coat layer having no light diffusibility. Moreover, one layer may be sufficient and it may be comprised by multiple layers, for example, 2-4 layers, and the combination of the light diffusible hard-coat layer and the transparent hard-coat layer which does not have light diffusibility may be sufficient. The refractive index of the material other than the light-transmitting particles of the hard coat layer is preferably in the range of 1.45 to 2.00.

  In this specification, a hard coat layer containing translucent particles on the order of several μm that changes light scattering properties or antiglare properties is also referred to as a light diffusing hard coat layer, and the hard coat does not contain the translucent particles. The layer is also referred to as a transparent hard coat layer.

  The laminated arrangement of the transparent hard coat layer and the light diffusing hard coat layer is not particularly limited. The transparent hard coat layer and the light diffusing hard coat layer may be arranged in this order from the substrate side, or the opposite arrangement may be employed.

  The hard coat film in the present invention may be coated with a functional layer other than the hard coat layer. Examples of these layers include an antistatic layer, a high refractive index layer, a low refractive index layer, and an antifouling layer. Is mentioned. The antistatic layer preferably contains conductive inorganic fine particles. The high refractive index layer preferably has a refractive index in the range of 1.50 to 2.00. The low refractive index layer preferably has a refractive index in the range of 1.20 to 1.48, and is preferably coated adjacent to the outside of the hard coat layer or the high refractive index layer. Also good. Further, an antifouling layer may be further provided on the low refractive index layer.

(Low refractive index layer)
The hard coat film in the present invention may be provided with a layer having a refractive index lower than that of the substrate (low refractive index layer) on the hard coat layer, and can also be used as an antireflection film.
In the present invention, a low refractive index layer can be provided outside the hard coat layer, that is, on the side farther from the substrate. By having a low refractive index layer, it is possible to impart an antireflection function to the antiglare film and further improve the antiglare property. The refractive index of the low refractive index layer is preferably set lower than the refractive index of the hard coat layer. When the refractive index difference between the low refractive index layer and the hard coat layer is too small, the antireflection property is lowered, and when it is too large, the color of the reflected light tends to be strong. The difference in refractive index between the low refractive index layer and the hard coat layer is preferably from 0.01 to 0.30, more preferably from 0.05 to 0.20.
The low refractive index layer can be formed using a low refractive index material. A low refractive index binder can be used as the low refractive index material. Further, the low refractive index layer can be formed by adding fine particles to the binder.

  As the low refractive index binder, a fluorine-containing copolymer can be preferably used. The fluorinated copolymer preferably has a structural unit derived from a fluorinated vinyl monomer and a structural unit for imparting crosslinkability.

(Fluorine-containing copolymer)
Examples of the fluorinated vinyl monomer mainly constituting the fluorinated copolymer include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, etc.), a part of (meth) acrylic acid or a fully fluorinated alkyl. Ester derivatives {for example, “Biscoat 6FM” (trade name), Osaka Organic Chemical Industry Co., Ltd., “R-2020” (trade name), manufactured by Daikin Industries, Ltd., etc.}, fully or partially fluorinated vinyl ethers, etc. Of these, perfluoroolefins are preferable, and hexafluoropropylene is particularly preferable from the viewpoint of refractive index, solubility, transparency, availability, and the like.

  Increasing the composition ratio of these fluorinated vinyl monomers can lower the refractive index, but the film strength tends to decrease. In the present invention, the fluorine-containing vinyl monomer is preferably introduced so that the fluorine content of the copolymer is 20 to 60% by mass, more preferably 25 to 55% by mass, and particularly preferably 30 to 50%. This is a case of mass%.

Examples of the structural unit for imparting crosslinking reactivity include units represented by the following (A), (B), and (C).
(A): a structural unit obtained by polymerization of a monomer having a self-crosslinkable functional group in the molecule in advance such as glycidyl (meth) acrylate or glycidyl vinyl ether,
(B): a monomer having a carboxy group, a hydroxy group, an amino group, 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.}
(C): A group having a crosslinkable functional group separately from a group that reacts with the functional groups (A) and (B) in the molecule and a structural unit of the above (A) and (B). Examples of the structural unit to be obtained (for example, a structural unit that can be synthesized by a technique such as allowing acrylic acid chloride to act on a hydroxy group).

  In the structural unit (C), the crosslinkable functional group is preferably a photopolymerizable group. Examples of the photopolymerizable group include (meth) acryloyl group, alkenyl group, cinnamoyl group, cinnamylideneacetyl group, benzalacetophenone group, styrylpyridine group, α-phenylmaleimide group, phenylazide group, sulfonylazide group, Carbonyl azide group, diazo group, o-quinonediazide group, furylacryloyl group, coumarin group, pyrone group, anthracene group, benzophenone group, stilbene group, dithiocarbamate group, xanthate group, 1,2,3-thiadiazole group, cyclopropene group And azadioxabicyclo group. These may be not only one type but also two or more types. Of these, a (meth) acryloyl group and a cinnamoyl group are preferable, and a (meth) acryloyl group is particularly preferable.

Specific methods for preparing the photopolymerizable group-containing copolymer include, but are not limited to, the following methods.
a. A method of esterifying by reacting a (meth) acrylic acid chloride with a crosslinkable functional group-containing copolymer containing a hydroxyl group,
b. A method of urethanization by reacting a (meth) acrylic acid ester containing an isocyanate group with a crosslinkable functional group-containing copolymer containing a hydroxyl group,
c. A method of reacting (meth) acrylic acid with a crosslinkable functional group-containing copolymer containing an epoxy group,
d. A method in which a crosslinkable functional group-containing copolymer containing a carboxy group is reacted with a containing (meth) acrylic acid ester containing an epoxy group for esterification.

The amount of the photopolymerizable group introduced can be arbitrarily adjusted. From the viewpoints of surface stability of the coating film, reduction of surface failure when coexisting with inorganic particles, and improvement of film strength, carboxy groups, hydroxy groups, etc. You may leave.
The introduction amount of the structural unit for imparting crosslinkability in the copolymer is preferably 10 to 50 mol%, more preferably 15 to 45 mol%, and particularly preferably 20 to 40 mol%. Is the case.

  The fluorine-containing copolymer particularly useful in the present invention is a random copolymer of a perfluoroolefin and vinyl ethers or vinyl esters. In particular, it preferably has a group capable of undergoing 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 polymerized units of the polymer. Regarding preferred polymers, JP-A-2002-243907, JP-A-2002-372601, JP-A-2003-26732, JP-A-2003-222702, JP-A-2003-294911, JP-A-2003-329804, JP-A-2004. -4444 and JP-A-2004-45462.

  In addition, the fluorine-containing copolymer useful in the present invention preferably has a polysiloxane structure introduced for the purpose of imparting antifouling properties. The method for introducing the polysiloxane structure is not limited. For example, as described in JP-A-6-93100, JP-A-11-189621, JP-A-11-228631, and JP-A-2000-313709, silicone macroazo A method for introducing a polysiloxane block copolymer component using an initiator; a method for introducing a polysiloxane graft copolymer component using a silicone macromer as described in JP-A-2-251555 and JP-A-2-308806. Is preferred. Particularly preferred compounds include the polymers of Examples 1, 2, and 3 of JP-A-11-189621, and copolymers A-2 and A-3 of JP-A-2-251555. It is preferable that these polysiloxane components are 0.5-10 mass% in a polymer, Most preferably, it is 1-5 mass%.

  The preferred molecular weight of the copolymer that can be preferably used in the present invention is a mass average molecular weight of 5000 or more, preferably 10,000 to 500,000, and most preferably 15,000 to 200,000. By using polymers having different average molecular weights in combination, it is possible to improve the surface state of the coating film and the scratch resistance.

  As described in JP-A-10-25388 and JP-A-2000-17028, a curing agent having a polymerizable unsaturated group may be appropriately used in combination with the above copolymer. Further, as described in JP-A-2002-145952, combined use with a compound having a fluorine-containing polyfunctional polymerizable unsaturated group is also preferable. Examples of the compound having a polyfunctional polymerizable unsaturated group include the polyfunctional monomer described in the antiglare layer. These compounds are particularly preferred because they have a large combined effect for improving scratch resistance, particularly when a compound having a polymerizable unsaturated group is used in the copolymer body.

(Fine particles)
The low refractive index layer may contain fine particles.
The coated amount of the fine particles may be contained in the low refractive index layer is preferably from 1 to 100 mg / ^{m 2,} more preferably 1 to 80 mg / ^{m 2,} more preferably from 1~70mg / ^{m 2.} If the coating amount of the fine particles is greater than or equal to the lower limit value, the effect of improving the scratch resistance is clearly manifested. If the coating amount is smaller than or equal to the upper limit value, fine irregularities are formed on the surface of the low refractive index layer, and the appearance and integrated reflectivity. This is preferable because there is no problem such as deterioration. Since the fine particles are contained in the low refractive index layer, the low refractive index is preferable.

  Specifically, the fine particles contained in the low refractive index layer are inorganic fine particles, hollow inorganic fine particles, or hollow organic resin fine particles, preferably having a low refractive index, particularly hollow inorganic fine particles. preferable. Examples of the inorganic fine particles include silica or hollow silica fine particles.

  The average particle size of such fine particles is preferably 30% or more and 100% or less of the thickness of the low refractive index layer, more preferably 30% or more and 80% or less, and further preferably 35% or more and 70% or less. That is, when the thickness of the low refractive index layer is 100 nm, the particle size of the fine particles is preferably 30 nm to 100 nm, more preferably 30 nm to 80 nm, and still more preferably 35 nm to 70 nm.

  The (hollow) silica fine particles as described above clearly show the effect of improving the scratch resistance if the particle diameter is not less than the above lower limit value, and if the particle diameter is not more than the above upper limit value, fine particles are formed on the surface of the low refractive index layer. This is preferable because irregularities are formed and problems such as deterioration in appearance and integrated reflectance do not occur.

  The (hollow) silica fine particles may be either crystalline or amorphous, and may be monodispersed particles or aggregated particles (in this case, the secondary particle diameter is 15% to 150% of the layer thickness of the low refractive index layer). It may be preferable). Two or more types of particles (types or particle sizes) may be used. The particle shape is most preferably a spherical diameter, but there is no problem even if it is indefinite.

In order to lower the refractive index of the low refractive index layer, it is particularly preferable to use hollow silica fine particles. The hollow silica fine particles have a refractive index of 1.17 to 1.40, more preferably 1.17 to 1.35, and still more preferably 1.17 to 1.33. 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, the radius r _i of the holes in the _particle, the radius of the outer shell of the particle is r _o, the porosity x is calculated by the following equation (3).

Equation (3): x = (4πr i 3/3) / (4πr o 3/3) × 100

  The porosity x is preferably 10 to 60%, more preferably 20 to 60%, and most preferably 30 to 60%. 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 difficult. In addition, the refractive index of these hollow silica particles was measured with an Abbe refractometer {manufactured by Atago Co., Ltd.}.

  From the viewpoint of improving antifouling properties, it is preferable to further reduce the surface free energy on the surface of the low refractive index layer. Specifically, it is preferable to use a fluorine-containing compound or a compound having a polysiloxane structure for the low refractive index layer.

  Examples of the additive having a polysiloxane structure include a reactive group-containing polysiloxane {for example, “KF-100T”, “X-22-169AS”, “KF-102”, “X-22-3701IE”, “X-22”. -164B "," X-22-5002 "," X-22-173B "," X-22-174D "," X-22-167B "," X-22-161AS "(product name), "AK-5", "AK-30", "AK-32" (trade name), manufactured by Toa Gosei Co., Ltd .; "Silaplane FM0725", "Silaplane FM0721" It is also preferable to add (trade name), manufactured by Chisso Corporation, etc.}. Moreover, the silicone type compound of Table 2 and Table 3 of Unexamined-Japanese-Patent No. 2003-112383 can also be used preferably. These polysiloxanes are preferably added in the range of 0.1 to 10% by mass of the total solid content of the low refractive index layer, particularly preferably 1 to 5% by mass.

  When the hard coat film obtained by the production method of the present invention is used in a liquid crystal display device, it is preferably disposed on the outermost surface of the display by providing an adhesive layer on one side. Further, the hard coat film obtained by the production method of the present invention may be used as an antireflection film as described above, and a polarizing plate may be combined. When the substrate is triacetylcellulose, triacetylcellulose is used as a protective film for protecting the polarizing layer of the polarizing plate. Therefore, it is preferable in terms of cost to use the antireflection film as it is for the protective film.

When the hard coat film obtained by the production method of the present invention is disposed on the outermost surface of the display by providing an adhesive layer on one side, or is used as it is as a protective film for a polarizing plate, it is sufficiently adhered. For this purpose, it is preferable to carry out a saponification treatment after forming the outermost layer on the substrate. 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 performing the saponification treatment, the surface of the substrate 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 with respect to water of the surface of the substrate opposite to the side having the outermost layer is 40 ° or less. More preferably, it is 30 ° or less, particularly preferably 20 ° or less.

〔Polarizer〕
The polarizing plate is mainly composed of two protective films that sandwich the polarizing film from both sides. The hard coat film in the present invention is preferably used for at least one of the two protective films sandwiching the polarizing film from both sides. The manufacturing cost of a polarizing plate can be reduced because the hard coat film in this invention serves as a protective film. Further, by using the hard coat film of the present invention as the outermost layer, reflection of external light and the like can be prevented, and a polarizing plate having excellent scratch resistance, antifouling property and the like can be obtained.
(Image display device)
The hard coat film in the present invention is used for image display devices such as liquid crystal display devices (LCD), plasma display panels (PDP), electroluminescence displays (ELD), cathode ray tube display devices (CRT), and surface electric field displays (SED). Can be applied. Particularly preferably, it is used for a liquid crystal display (LCD) and an electroluminescence display (ELD). Since the hard coat film in the present invention has a substrate, the substrate side is adhered to the image display surface of the image display device.

  The hard coat film in the present invention, when used as one side of the surface protective film of the polarizing film, is twisted nematic (TN), super twisted nematic (STN), vertical alignment (VA), in-plane switching (IPS), optical It can be preferably used for a transmissive, reflective, or transflective liquid crystal display device of a mode such as a curry compensate bend cell (OCB).

  In order to describe the present invention in more detail, examples will be described below, but the present invention is not limited thereto. Unless otherwise specified, “part” and “%” are based on mass.

[Examples 1 to 6, Comparative Examples 1 and 2]
(1) Preparation of coating liquid for hard coat layer

{Preparation of hard coat layer coating solution (HC1)}
Mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate 45.1 parts by mass (Nippon Kayaku Co., Ltd .: PET30)
38.7 parts by mass of silica fine particles (manufactured by Nissan Chemical Industries, Ltd .: MEK-ST; particle size: 10 to 20 nm)
Irgacure 184 (C-18 in the text) 1.4 parts by mass (photopolymerization initiator; manufactured by Ciba Specialty Chemicals Co., Ltd.)
Methyl ethyl ketone 4.4 mass parts Methyl isobutyl ketone 10.5 mass parts

Similarly, the following coating liquid for hard coat layer (HC2) was also prepared.
{Preparation of hard coat layer coating solution (HC2)}
Dipentaerythritol hexaacrylate 56.3 parts by weight Irgacure 184 1.7 parts by weight Methyl ethyl ketone 31.5 parts by weight Methyl isobutyl ketone 10.5 parts by weight

(2) Coating of hard coat layer The coating liquid for hard coat layer was applied to a triacetyl cellulose film (TAC-TD80U, manufactured by FUJIFILM Corporation. Refractive index 1.48) having a thickness of 80 μm. The film surface temperature, illuminance, and irradiation time described in Table 1 below were applied under a nitrogen purge after coating with a bar coater to a solid film thickness of 15 μm as described in 1 and drying at 60 ° C. for 60 seconds. The film was cured by irradiating with ultraviolet rays for a non-irradiation time to form a hard coat layer, and a hard coat film was produced. In each example, the film surface temperature was controlled to 25 ° C. by using a temperature-controlled wind and a temperature-controlled roller in order to prevent an increase in the film surface temperature due to the radiant heat of the light source. However, the film surface temperature was measured with a non-contact infrared temperature measuring device at the temperature-controlled outlet of the roller. Further, non-irradiation was performed by passing through a light-shielded zone in which a plurality of rollers were arranged. At this time, the ambient temperature and the roller temperature were about 25 ° C.
The film thickness of any hard coat layer was 15 μm.
Moreover, the hardening rate (%) in the following table | surface was measured as follows.
The absorption intensity at 812 cm ⁻¹ , which is the characteristic absorption of the out-of-plane nucleation vibration of the acrylic group, is measured by FT-IR (apparatus: manufactured by Thermo Nicolet Japan, Nicolet 710), and the curing rate (%) is calculated from the following formula. did.

[Comparative Example 3]
A hard coat film was produced in the same manner as in Example 1 except that a temperature-controlled wind and a temperature-controlled roller were not used during light irradiation.

[Comparative Example 4]
A hard coat film was produced in the same manner as in Example 1 except that the film surface temperature at the second light irradiation was set to 100 ° C.

(3) Evaluation of hard coat film About these obtained hard coat film samples, the following items were evaluated. The results are shown in Table 1.

[1. Curl evaluation]
Each hard coat film was cut into a size of 3 mm × 35 mm, and was classified according to the following criteria from the radius of curvature thereof to evaluate curl properties.
◎: 20 cm or more ○: larger than 10 cm and less than 20 cm ×: 10 cm or less

[2. Pencil hardness evaluation]
The pencil hardness evaluation described in JIS K 5400 was performed as an index of scratch resistance. Each hard coat film was conditioned at a temperature of 25 ° C. and a humidity of 60% RH for 1 hour, and then, using a 3H test pencil specified in JIS S 6006, scratches were evaluated in an evaluation of n = 5 at a load of 500 g. Those having less than 3 were evaluated as 3H, and the same evaluation was performed using a 4H pencil, and those having less than 3 scratches were evaluated as 4H.

As is apparent from the results shown in Table 1, it can be seen that Comparative Examples 1 and 2 in which the light irradiation was not performed twice or more and the non-irradiation time was not provided have a large curl. Moreover, the comparative example 3 which does not use the temperature-controlled wind and temperature-controlled roller at the time of light irradiation exceeds the film surface temperature of 20 to 30 ° C., and even if the light irradiation is performed twice or more, the curl does not occur. You can see that it ’s big. It can be seen that even when the light irradiation is performed twice or more, the curl is large also in Comparative Example 4 in which the film surface temperature is irradiated at 100 ° C. without controlling the film surface temperature at 20-30 ° C.
On the other hand, in Examples 1 to 6, in which light irradiation was performed twice or more and an unirradiation time of 10 to 60 seconds was provided between each irradiation, the hardness of the hard coat layer was high and the scratch resistance of a pencil or the like was also good. And the curl is small.
In particular, it can be seen that Example 3, which has a long non-irradiation time of 60 seconds, is particularly excellent in curling suppression although the productivity is inferior due to the long non-irradiation time.
Moreover, it turns out that curl suppression is especially excellent also about Example 5 which suppressed light illuminance after making it harden | cure 50% or more to 100 mW / cm < ² > or less, and increased the frequency | count of irradiation.

Claims (7)

  A method for producing a hard coat film, comprising: applying a composition containing a photopolymerizable compound on a substrate; and then polymerizing the photopolymerizable compound by light irradiation to form a hard coat layer. In the step of forming the hard coat layer, the film surface temperature when performing the light irradiation is controlled to 20 ° C. to 30 ° C., the light irradiation is performed twice or more, and 10 seconds to 60 seconds are not applied between each light irradiation. A method for producing a hard coat film, wherein an irradiation time is provided.   The method for producing a hard coat film according to claim 1, wherein the first non-irradiation time is provided after 30% to 50% of the hard coat layer is cured by polymerization of the polymerizable compound.   The manufacturing method of the hard coat film of Claim 1 or 2 whose irradiation time in the 1st light irradiation is 0.01 to 1 second. The hard coat film according to any one of claims 1 to 3, wherein the light illuminance after curing by 50% or more as a curing rate of the hard coat layer by polymerization of the photopolymerizable compound is 100 mW / cm ² or less. Manufacturing method.   The manufacturing method of the hard coat film of any one of Claims 1-4 which provides the said non-irradiation time 1 or 2 times in the process of forming the said hard-coat layer.   The manufacturing method of the hard coat film of any one of Claims 1-5 by which control of the film surface temperature when performing the said light irradiation is performed with the temperature-controlled wind and the temperature-controlled roller.   The hard coat film manufactured by the manufacturing method of any one of Claims 1-6.