JP4296874B2 - Hard coat film and method for producing the same - Google Patents

Description

  The present invention relates to a hard coat film having a coating layer on a hard coat layer, which has improved surface defects such as repellency and leakage generated when a coating liquid is applied onto a hard coat layer containing a pigment.

  In recent years, there is an application in which a functional thin film is formed on the hard coat layer in order to impart functionality such as antireflection, improvement of transmittance, antistatic, and near infrared ray blocking on the surface of the hard coat film. Usually, many hard coat films are obtained by applying and curing an acrylic monomer such as dipentaerythritol hexaacrylate on a substrate, and the surface of the hard coat layer is hydrophobic. When applying a hard coat layer coating solution, a fluorine leveling agent and / or a silicone leveling agent may be added as a coating aid in order to ensure a good coating surface. However, the addition of these auxiliaries reduces the surface energy of the hard coat layer, and when the functional thin film is formed on the hard coat layer by a wet method, surface defects such as repellency and leakage are likely to occur. Become. Furthermore, when the hard coat layer has irregularities in order to impart antiglare properties, there has been a problem that planar defects such as repellency and leakage are more likely to occur starting from surface protrusions.

In JP 2002-293964 A and JP 2002-361769 A, chemical treatments such as physical treatment such as corona treatment, plasma treatment and ozone treatment, and chemical treatment such as alkali treatment are performed in order to eliminate surface defects such as repellency and leakage. It is reported to be effective to do. However, in this method, when the surface roughness (SRa) of the substrate exceeds 0.10, surface defects such as repellency and leakage are likely to occur from the surface protrusion, and the substrate is deformed when the degree of treatment is increased. There was a problem that occurred.
Further, JP 2001-272503 A discloses a case where a hard coat layer is hydrophilized and a corona discharge treatment that deforms the base material is not performed even when a hydrophilic functional layer is applied. A technique for suppressing repellency and leakage is disclosed. However, since a surfactant is added to the hard coat layer, there is a problem that the hardness of the hard coat layer is lowered.

JP 2002-293964 A JP 2002-361769 A JP 2001-272503 A

  In the conventional technology, when irregularities are formed on the surface of the hard coat layer in order to impart anti-glare properties, defects such as repellency and leakage are more likely to occur than hard coat layers with high surface smoothness. Had.

  The present invention has been made in view of the circumstances of the prior art, and the object thereof is a hard coat layer having an antiglare property due to surface irregularities, and a functional thin film having no surface defects such as repellency and leakage on the hard coat layer. It is to provide a hard coat film provided with a coating layer.

It has been found that these problems can be achieved by the following method of the present invention. That is, the present invention is a hard coat film in which a hard coat layer and a functional thin film layer are formed in this order on at least one surface of a transparent substrate, the hard coat layer comprising silicon dioxide fine particles and a polymerizable unsaturated double bond-containing compound. It is basically formed from a crosslinked form, and the SRa measured by three-dimensional surface roughness meter (center plane average roughness) is 0.10～0.40Myuemu, the functional thin film, the surface energy y (MN / m) On the hard coat layer satisfying the relationship of 15x + 29 ≦ y <37, when SRa (center plane average roughness) measured by a three-dimensional surface roughness meter is x (μm) , surface tension Is formed by applying a functional thin film forming coating solution having a thickness of 20.0 to 30.0 mN / m, and the thickness of the functional thin film is 0.005 μm to 0.5 μm. Characteristic hard coat film A. In particular, when the fluorine-based and / or silicon-based surfactant is contained in the hard coat layer coating solution, a great effect is achieved.

Further, the present invention is basically composed of a crosslinked body of silicon dioxide fine particles and a polymerizable unsaturated double bond-containing compound on at least one surface of a transparent substrate, and SRa (measured with a three-dimensional surface roughness meter). After providing a hard coat layer having a center surface average roughness (0.10 to 0.40 μm), the hard coat layer is subjected to corona treatment, and the surface energy of the hard coat layer is set to y (mN / m) After adjusting SRa (central surface average roughness) measured with a three-dimensional surface roughness meter of the hard coat layer to x (μm) , the surface tension was 28.0. A function in which a coating solution for forming a functional thin film in a range of ˜30.0 mN / m is applied and dried on a hard coat layer after corona treatment by a wet method, and a film thickness is 0.005 μm to 0.5 μm. Characterized by forming a conductive thin film It is a method of manufacturing a hard coat film to

  In the present invention, by measuring the surface roughness of the hard coat layer, it is possible to estimate the amount of treatment required at the time of corona discharge, and there is no surface defects such as repellency, leakage, and surface deterioration of the hard coat layer, A hard coat film provided with a functional coating layer can be formed.

  Although it does not specifically limit as a base material which has transparency in the hard coat film of this invention, Various polymer films excellent in heat resistance are suitable. Specific examples include a wide range of polymer films such as polyethylene terephthalate, polycarbonate, polyvinyl chloride, polyethylene, polypropylene, polyamide, norbornene resin (cyclic olefin copolymer), cellulose resin such as triacetyl cellulose, and polysulfone. Although it is possible, it is not particularly limited to these.

  The thickness of these films is not particularly limited. However, if the thickness is too thin, the film strength becomes weak, and if it is too thick, winding becomes difficult. However, the thickness is preferably 20 to 1000 μm, but is not limited thereto.

  The hard coat layer of the present invention is basically composed of a crosslinked product of silicon dioxide fine particles and a polymerizable unsaturated double bond-containing compound. As the polymerizable unsaturated double bond-containing compound, a curable resin such as a thermosetting resin or a radiation curable resin can be used, and it is particularly preferable to use a polyfunctional polymerizable unsaturated double bond-containing compound. It is more preferable to add a polymerization initiator, a polymerization accelerator, a leveling agent, and a filler to these compounds as necessary.

  Polyfunctional polymerizable unsaturated double bond-containing compounds include esters of polyhydric alcohols and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-dichlorohexane diacrylate, pentaerythritol tetra ( (Meth) acrylate), pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, di Pentaerythritol hexa (meth) acrylate, 1,3,5-cyclohexanetriol trimethacrylate, polyurethane polyacrylate, polyester polyacrylate), derivatives of vinylbenzene (eg, 1 Examples include 4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg, divinyl sulfone), acrylamide (eg, methylenebisacrylamide), methacrylamide, and the like. However, the present invention is not limited to this.

  It is particularly effective to add a polymerization initiator for the purpose of efficiently initiating the polymerization of these polyfunctional polymerizable unsaturated double bond-containing compounds. As the polymerization initiator, acetophenones, benzophenones, Michler's benzoyl are used. Benzoates, α-amyloxime esters, tetramethylthiuram monosulfide and thioxanthones are preferred. In addition to a polymerization initiator, a sensitizer may be used for the purpose of promoting polymerization. Examples of the sensitizer include n-butylamine, triethylamine, tri-n-butylphosphine, Michler's ketone, and thioxanthone skeleton compounds. 0.1-15 weight part is preferable with respect to 100 weight part of polymeric compounds, and, as for the addition amount of these initiators and a polymerization accelerator, 1-10 weight part is more preferable. If it is 15 parts by weight or more, it will start to inhibit curing, and if it is too little, the effect cannot be obtained.

  Examples of the active energy ray for curing these polyfunctional polymerizable unsaturated double bond-containing compounds include radiation, electron beam, particle beam, gamma ray, ultraviolet ray and the like. From near-ultraviolet rays using mercury lamps to vacuum ultraviolet rays using excimer lasers can be used.

In the present invention, the silicon dioxide fine particles to be contained in the hard coat in order to impart antiglare properties are not particularly limited, but the surface of the silicon dioxide fine particles is subjected to surface treatment with an organic substance or the like from the viewpoint of pigment dispersion stability. It is preferable to use silicon dioxide fine particles.
Examples of such silicon dioxide include hydrophobic micronized silica “Silo Hovic” manufactured by Fuji Silysia. Furthermore, it is preferable to coat the pigment surface with an additive such as a dispersant and / or an anti-settling agent for the purpose of improving the affinity with the hard coat resin and preventing aggregation and settling of the pigment.

  As a method for coating the surface of the silicon dioxide fine particles, it is preferable to be performed in a solution. When the silicon dioxide fine particles are mechanically finely dispersed, a surface modifier is present together or the silicon dioxide fine particles are finely dispersed. Later, a method of adding a surface modifier and stirring can be raised. As the solvent in this case, an organic solvent having a high polarity such as alcohols, ketones and esters is preferable. Examples of the disperser include an ultrasonic disperser, a disper, a homogenizer, a dissolver, a polytron, a paint shaker, a sand grinder, a kneader, an Eiger mill, a dyno mill, and a coball mill, but are not limited thereto.

  The hard coat layer of the present invention can have sufficient antiglare properties when the SRa (center surface average roughness) measured with a three-dimensional surface roughness meter is 0.10 to 0.40 μm.

  The leveling agent added to the coating solution to prevent coating unevenness, drying unevenness, point-like defects, etc. when applying the hard coat layer, and to obtain good surface properties is fluorine and / or silicon leveling. It is preferable to use an agent. Examples of the fluorine leveling agent include perfluoroalkyl sulfone group-containing oligomers. Examples of the silicon-based leveling agent include polydimethylsiloxane in which side groups and terminal groups of the main chain are modified with various substituents such as oligomers such as ethylene glycol and propylene glycol. By blending a fluorine-based or silicone-based leveling agent in the hard coat layer coating liquid, it is possible to provide the hard coat layer with a uniform thickness, but as a result, the surface energy of the hard coat layer is reduced. It becomes difficult to provide a coating layer on the hard coat layer. For this reason, in the present invention, corona treatment is performed on the hard coat layer.

  Next, corona discharge treatment for setting the surface energy of the hard coat layer to a desired surface energy will be described. The corona discharge treatment is the most well-known physical treatment for controlling the surface energy, and the treatment can be performed by a known method.

In the present invention, the corona treatment is preferably performed in the following range. That is, when the surface energy of the hard coat layer after the corona treatment is y (mN / m) and the surface roughness (SRa) of the hard coat layer is x (μm) , the surface energy y is in the range of 15x + 29 ≦ y <37. Control with. When the surface energy is small, the coating defects of the coating layer provided on the hard coat layer increase. As the surface roughness of the hard coat layer increases, repelling is more likely to occur. Therefore, a suitable surface energy value varies depending on the surface roughness of the hard coat layer. In addition, when the corona treatment strength is increased to increase the surface energy of the hard coat layer, the surface energy can be increased, but during the treatment, a strong discharge occurs between the pigment projections and the electrodes of the hard coat layer. Only the portion is damaged and may cause appearance defects, which is not preferable.

The surface energy can be controlled by returning the treatment intensity of the corona treatment. In order to set the surface energy of the hard coat layer within the above range, the corona treatment strength is preferably 0.001 to 3 KV · A · min / m ² , more preferably 0.15 to 0.5 KV · A ·. Min / m ² . If the treatment strength is lower than 0.001 KV · A · min / m ² , the surface treatment effect cannot be obtained, and if it is higher than 3 KV · A · min / m ^{2, the} hard coat film is generated by heat generated during the treatment. It itself is deformed and is not preferable.

  In the present invention, the functional thin film is formed by coating a functional thin film forming coating solution on the hard coat layer. In particular, when the thickness of the functional thin film is as thin as 0.005 μm to 0.5 μm, the solid content concentration of the coating liquid becomes small, and the coating liquid (coating liquid for functional thin film formation) becomes solvent-rich. The surface tension is as small as 28.0 to 30.0 mN / m. When a coating liquid having a small surface tension is applied to an uneven surface, coating defects (missing and repelling) are likely to occur, but this can be suppressed in the present invention.

  The functions here include durability, corrosion resistance, sliding resistance, antifouling properties, design, conductivity, insulation, antistatic properties, dielectric properties, superconductivity, optical properties (transparency, low refractive index, The components include silane compounds, silica, alumina, zirconia, yttria, tin oxide, barium titanate, TiC, TiN, SiC, Si3N4, ITO, silicon, silicide, tungsten. , Aluminum and its alloys, molybdenum and its alloys, titanium and its alloys, platinum and its alloys, palladium and its alloys, copper and its alloys, iron and its alloys, gold, various oxides and non-oxide amorphous be able to. Among these, optical characteristics can be cited as a function suitable for application of the present invention.

  In the present invention, as a means for forming the hard coat layer and the functional thin film, a commonly known wet coating method such as a bar coater, a die coater, a gravure coater, or a roll coater can be used.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, the characteristic value in an Example is measured with the following method.
(1) Surface roughness (SRa)
SRa (central surface average roughness) was measured using a three-dimensional surface roughness meter (SE-30K) manufactured by Kosaka Laboratory.
(2) Surface energy Plastics specified in JIS K6768 using a mixture for wetting tension test (No. 22.6 to No. 73.0, manufactured by Wako Pure Chemical Industries, Ltd.) in an environment of a temperature of 23 ° C. and a humidity of 65%. Measurements were made by film and sheet-wetting tension test methods.

(3) Planar defect Using a magnifying glass with a magnification of 50 times, the state of repelling and missing was confirmed.
○: No repelling is observed when the haze degree is increased or confirmed by a loupe. Δ: No increase in haze degree is observed, but a slight repellency that does not cause a problem at the pigment protrusion is observed slightly when confirmed by a loupe. X: Increase in haze degree is observed, and noticeable repellency is observed in the pigment protrusions as confirmed by a loupe. (4) Surface degradation of hard coat layer ○: No change is observed before and after corona treatment ×: Partial after corona treatment (5) Surface Tension Measurement Using a Shimadzu Corporation, Dunui surface and an interfacial tension tester, measurement was performed at a liquid temperature of 20 ° C.

-Examples 1-3 and Comparative Examples 2-4
<Creation of hard coat layer>
A transparent polyethylene terephthalate film (PET) (manufactured by Teijin Limited: SG-50) having a thickness of 50 μm was used as a support. The hard coat layer coating solution was adjusted to 40 parts by weight so that the following silicon dioxide pigment and UV curable resin ratio (P / B) would be 1/99, and 0.3 parts by weight of the following silicon leveling agent was added. Was diluted with a solvent of toluene / MIBK = 50/50 so as to be 100 parts by weight. The hard coat layer coating solution was applied onto the support using a Meyer bar so that the dry film thickness was 4 μm, and then dried at 80 ° C. for 1 minute, and then 250 mJ / cm ² . A hard coat layer was prepared by irradiating with ultraviolet rays and cured, and the surface roughness SRa was measured.
・ Silicon dioxide pigment (manufactured by Fuji Silysia Co., Ltd .: silo hovic 100)
・ UV curable resin (Arakawa Chemical Co., Ltd .: Beam Set KU575CS-B)
・ Silicon-based leveling agent (BYK-325, manufactured by BYK Chemie)

<Corona treatment of hard coat film>
A sample which was not subjected to corona discharge treatment in the hard coat film prepared above was designated as Comparative Example 2. By using a corona treatment machine manufactured by Kasuga Denki Co., Ltd., the gap between the electrode at the time of treatment and the dielectric roll is 1.6 mm, corona discharge treatment is performed, and the speed during corona treatment is changed to 0.16, 0.26. , 0.39, 0.52, 1.04 KV · A · min / m ² were subjected to corona treatment, and the obtained samples were respectively Comparative Example 3, Examples 1, 2, 3, and Comparative Examples. The sample of No. 4 was observed, and the surface state of the hard coat layer was observed and the surface energy was measured.

-Example 4 and Comparative Examples 5-7
Example 4, Comparative Example 5-7 In the preparation of the hard coat layer described above, silicon dioxide pigments and the ultraviolet curing resin ratio (P / B) was prepared in the same manner except that the 15/85, the surface roughness SR a Measurements were made. Samples that were not subjected to corona discharge treatment were referred to as Comparative Example 5, and samples obtained by performing corona treatment at treatment amounts of 0.16, 0.39, 0.52 KV · A · min / m ² were compared. In Example 6, Example 4, and Comparative Example 7, the surface state of the hard coat layer was observed and the surface energy was measured.

Examples 5-7, Comparative Example 8
Examples 5 to 7 and Comparative Example 8 were the same except that the silicon dioxide pigment was silophobic 603 and the ratio of silicon dioxide pigment and ultraviolet curable resin (P / B) was 5/95 in the preparation of the hard coat layer. The surface roughness SRa was measured. Samples that were not subjected to corona discharge treatment were referred to as Comparative Example 8, and samples obtained by performing corona treatment at treatment amounts of 0.16, 0.26, 0.39 KV · A · min / m ² were carried out. In Examples 5, 6, and 7, the hard coat layer surface state was observed and the surface energy was measured.

-Examples 8-9, comparative examples 9-10
In Examples 8 to 9 and Comparative Examples 9 to 10, in the production of the above hard coat layer, the silicon dioxide pigment was silo hovic 200, and the silicon dioxide pigment and ultraviolet curable resin ratio (P / B) was 5/95. The surface roughness SRa was measured in the same manner. Samples that were not subjected to corona discharge treatment were referred to as Comparative Example 9, and samples obtained by performing corona treatment at treatment amounts of 0.16, 0.26, 0.39 KV · A · min / m ² were compared. In Example 10 and Examples 8 and 9, the hard coat layer surface state was observed and the surface energy was measured.

Example 10 and Comparative Examples 11-14
Example 10 and Comparative Examples 11 to 14 were the same except that the silicon dioxide pigment was silo-hovic 200 and the silicon dioxide pigment to ultraviolet curable resin ratio (P / B) was 10/90 in the preparation of the hard coat layer. The surface roughness SRa was measured. A sample which was not subjected to corona discharge treatment was obtained as Comparative Example 11, and obtained by performing corona treatment at a treatment amount of 0.16, 0.26, 0.39, 0.52 KV · A · min / m ² . The samples were set as Comparative Examples 12 and 13, Example 10, and Comparative Example 14, respectively, and the surface state of the hard coat layer was observed and the surface energy was measured.

Comparative example 1
A sample that was not subjected to corona discharge treatment in a hard coat film prepared in the same manner except that no pigment was added in the preparation of the hard coat layer was used as Comparative Example 1, and the surface roughness SRa was measured. Observation and measurement of surface energy were performed.

(3) Coating liquid for hard coat layer coating On the hard coat layer of the hard coat films of Examples 1 to 10 and Comparative Examples 1 to 14 obtained above, a coating liquid having the following composition was applied to the Mayer bar. Table 1 shows the results of coating the hard coat layer so that the dry film thickness was 0.1 μm, and then drying at 120 ° C. for 1 minute to confirm the surface defects.
(Coating liquid for hard coat layer overcoating)
Silane coupling agent 20.0 parts by weight (manufactured by Nihon Unicar Co., Ltd .: APZ-6633)
IPA 80.0 parts by weight The surface tension of the coating solution was 28.6 mN / m.

As is clear from the above results, when the surface roughness is different, the surface tension of the coated substrate is the same, but the susceptibility to surface defects such as repellency and leakage is different. If the amount of corona treatment discharge is not increased, surface defects such as repellency and leakage cannot be eliminated, but if the amount of discharge is increased, the hard coat layer surface deteriorates. Both defects and surface degradation of the hard coat layer were good.

Claims (3)

A hard coat film in which a hard coat layer and a functional thin film layer are formed in this order on at least one surface of a transparent substrate, and the hard coat layer is basically composed of a crosslinked product of silicon dioxide fine particles and a compound containing a polymerizable unsaturated double bond. SRa (central surface average roughness) measured by the three-dimensional surface roughness meter is 0.10 to 0.40 μm, the surface energy is y (mN / m), and the three-dimensional surface roughness When the SRa (center surface average roughness) measured by the meter is x (μm) , the functional thin film has a surface tension of 28.0 on the hard coat layer satisfying the relationship of 15x + 29 ≦ y <37. A hard coat characterized by being formed by applying a functional thin film forming coating solution of 30.0 mN / m, and the functional thin film having a thickness of 0.005 μm to 0.5 μm the film. The hard coat film according to claim 1, characterized in that it contains a fluorine-based and or silicon-based surfactant in the hard coat layer.
SRa (central surface average roughness) measured basically with a three-dimensional surface roughness meter composed essentially of a crosslinked product of silicon dioxide fine particles and a polymerizable unsaturated double bond-containing compound on at least one surface of a transparent substrate. Is applied to the hard coat layer, the surface energy of the hard coat layer is set to y (mN / m) , and the hard coat layer is coated with a hard coat layer having a thickness of 0.10 to 0.40 μm. The surface tension is adjusted to 28.0 to 30.0 mN / m after adjusting so that 15x + 29 ≦ y <37 when SRa (central surface average roughness) measured by a three-dimensional surface roughness meter is x (μm). A functional thin film having a thickness of 0.005 μm to 0.5 μm is formed by applying a coating solution for forming a functional thin film in the range of 1 to 5 mm on the hard coat layer after corona treatment by a wet method. Hard coat characterized by Method of producing a film.