JP2016088954A - Uv curable hard coating agent and weather-resistant hard coat film applied therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coating agent that can form a hard coat layer that has weather resistance, is easy to clean, and has high surface hardness, and a weather-resistant hard coat film applied therewith.SOLUTION: The present invention provides a hard coating agent comprising a siloxane oligomer added with an acryloyl group, a photopolymerization initiator, and at least one selected from the group consisting of colloidal silica, nano silica, and nano zinc oxide powder.SELECTED DRAWING: None

Description

  The present invention relates to a hard coating agent for forming a hard coat layer on the surface of a film to be attached to a window or the like, and a hard coat film on which the hard coat agent is applied.

  In recent years, transparent window films that absorb infrared and ultraviolet light applied to windows have been used. By sticking such a film to a window, it is possible to provide a heat shielding function or prevent ultraviolet light from entering while maintaining the function as a window.

  A hard coat layer is usually formed on the window film to be attached to the window so that the surface is not damaged. In particular, when a film is applied to the outside of an outdoor window, the hard coat layer is exposed to the outside air, wind and rain, electromagnetic waves, etc., and may deteriorate over time, so a hard coat layer having weather resistance is formed. (For example, patent document 1).

  The hard coat layer having weather resistance has a soft surface and is easily scratched, and dirt such as dust and dust adheres to it. Therefore, time and cost are required for cleaning.

  As a method for improving the cleanability of a film, for example, Patent Document 2 describes a method in which a dot-like material is provided on a hard coat layer and an overcoat layer is further formed thereon.

JP 2008-200903 A Japanese Patent Laid-Open No. 2003-026832

  However, it is necessary to provide a dot-like material on the hard coat layer, and further to provide a layer separately from the hard coat layer, which requires manufacturing costs. Accordingly, an object of the present invention is to provide a hard coating agent that can form a hard coat layer having weather resistance, easy cleaning, and high surface hardness, and a weather resistant hard coat film coated with the hard coating agent.

In order to achieve the above object, the present inventor has conducted extensive research and as a result, the hard coating agent includes a compound having a specific structure, thereby having weather resistance, easy cleaning, and surface hardness. It was found that a hard coating agent capable of forming a hard coat layer having a high thickness and a weather-resistant hard coat film coated with the hard coating agent were obtained. That is, the present invention is a UV curable hard coating agent comprising a siloxane oligomer to which an acryloyl group represented by the following formula (1) is added, and a photopolymerization initiator.
(In the formula, n is an integer of 5 to 20.)

  The present invention also provides a weather resistant hard coat film in which the UV curable hard coating agent is applied to a substrate.

  As described above, according to the present invention, it is possible to provide a hard coating agent capable of forming a hard coat layer having weather resistance, easy cleaning and high surface hardness, and a weather resistant hard coat film coated with the hard coating agent. Can do.

[UV curable hard coating agent]
The UV curable hard coating agent according to the present invention is a solution for forming a hard coat layer on a film or the like. In the present invention, a siloxane oligomer to which an acryloyl group represented by the formula (1) is added (hereinafter, And sometimes a siloxane oligomer) and a photopolymerization initiator.

The siloxane oligomer used in the present invention can be produced, for example, as follows. Alkyl silicate Si (X) ₄ (wherein X is an alkoxy group that produces silanol by hydrolysis, for example, methoxy, ethoxy, propoxy, or butoxy) is hydrolyzed in the presence of a catalyst. After decomposing, the acrylate monomer can be mixed and heated for copolymerization to produce.

  In the siloxane oligomer having an acryloyl group added in the present invention, the silanol group has a hydrophilic property and the acryloyl group has an oiling property. That is, even if dust or dirt adheres to the surface of the hard coat layer, it can be easily washed away with water by washing with water. Since water droplets remain on the normal hard coat layer, it cannot be washed cleanly. However, if the hard coating agent contains the siloxane oligomer used in the present invention, water droplets are hardly formed on the formed hard coat layer.

  Further, the siloxane oligomer used in the present invention has an acryloyl group, and the silanol group simultaneously undergoes condensation polymerization by the reaction heat of the acryloyl group that undergoes radical polymerization when irradiated with UV. Thus, it is presumed that a polymer having a siloxane bond having -Si-O- as the main skeleton can be formed in a short time, and a hard coat layer having a hard, dense and flexible structure can be formed in a short time. Thus, mass production is facilitated if it can be formed in a short time.

  The photopolymerization initiator used in the present invention is not particularly limited as long as it photopolymerizes a siloxane oligomer, and examples thereof include a photopolymerization initiator having an effective excitation wavelength peak of 360 nm or more. Specifically, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, and 2,4,4 Phosphine compounds such as 6-trimethyl-diphenyl-phosphine oxide; Thioxanthone compounds such as 2-chlorothioxanthone, 2-methylthioxanthone, and 2-isopropylthioxanthone; 4,4′-bis (dimethylamino) ) Benzophenone and benzophenone compounds such as 4,4′-bis (diethylamino) benzophenone; 4,4′-diazidochalcone, 1,3-bis (4′-azidobenzal) acetone, 2,6-bis (4 ′) -Azidobenzal) cyclohexanone, 2,6-bis (4'-azi Benzal) -4-methylcyclohexanone, naphthoquinone (1,2) diazide (2) -5-sulfonic acid salt or ester, diazo resin, 4,4'-diazidostilbene-2,2'-disulfonic acid, 3-bis (4'-azidobenzal) -2-propanone-2'-sulfonic acid, sodium 1,3-bis (4'-azidobenzal) -2-propanone-2,2'-disulfonic acid, 1,3-bis (4'-azidocinnalidene) -2-propanone, azidopyrene, 3-sulfonylazide benzoic acid, 4-sulfonylazide benzoic acid, 2,6-bis (4'-azidobenzal) -cyclohexanone-2,2'-disulfone Acid and its sodium salt, and 2,6-bis (4'-azidobenzal) -methyl-cyclohexanone-2,2'-disulfonic acid and Azide compounds such as sodium salt of triphenylpyrylium perchloric acid, 4-methoxyphenyl-2,6-diphenylpyrylium perchloric acid, 4-butoxyphenyl-2,6-diphenylpyrylium perchloric acid, triphenyl Phenylpyrylium compounds such as phenylthiopyrylium perchloric acid and 4-methoxyphenyl-2,6-diphenylthiopyrylium perchloric acid; 2,5-bis (4′-diethylaminobenzal) cyclopentanone, Examples include 1-acetylamino-4-nitronaphthalene, 5-nitroacenaphthene, and 1-nitropyrene. From the viewpoint of a long wavelength UV curable type, a phosphine compound is preferable. The photopolymerization initiator can contain one or more of the above compounds.

  A photoinitiator can be 0.1-15 weight part with respect to 100 weight part of siloxane oligomers shown by Formula (1), It is preferable that it is 0.5-7 weight part. When there are few photoinitiators, photopolymerization may not fully advance, and when there are many, a weather resistance may worsen.

  The hard coating agent according to the present invention preferably contains an ultraviolet absorber. Examples of the ultraviolet absorber include organic and inorganic ultraviolet absorbers having an effective absorption wavelength of 270 to 380 nm. Preferred organic ultraviolet absorbers include benzotriazole and triazine ultraviolet absorbers. Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-t-butylphenyl) benzotriazole, 2- ( 2'-hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2 -(2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3', 5'-di-t-amylphenyl) benzotriazole 2- (2′-hydroxy-4′-octoxyphenyl) benzotriazole, and 2- {2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -te La hydro) -5'-methylphenyl} benzotriazole. Examples of triazine ultraviolet absorbers include hydroxyphenyl triazine ultraviolet absorbers such as 2,4-bis-2-hydroxy-4-butoxyphenyl-6- (2,4-dibutoxyphenyl) -1,3,5 triazine Etc. Examples of the inorganic ultraviolet absorber include zinc oxide, titanium oxide (titania), and cerium oxide. In addition, a copolymer of an organic or inorganic ultraviolet absorber and an organic resin or a silicone resin can also be used. As the ultraviolet absorber, hydroxyphenyltriazine is preferable.

  An ultraviolet absorber can be 0.5-5 weight part with respect to 100 weight part of siloxane oligomer shown by Formula (1), It is preferable that it is 0.8-3.0 weight part. If the amount of the ultraviolet absorber is small, the ultraviolet rays may not be sufficiently absorbed, and if it is large, the UV curing may be inhibited.

  The hard coating agent according to the present invention preferably contains colloidal silica, nano silica, or nano zinc oxide powder, more preferably contains colloidal silica or nano silica, and more preferably contains colloidal silica. By including these, it is possible to improve easy-cleaning properties and the like. Commercial products can be used for these. These can be 5 to 50 parts by weight, preferably 10 to 40 parts by weight, based on 100 parts by weight of the siloxane oligomer represented by the formula (1).

  The hard coating agent according to the present invention preferably contains an infrared absorber. Examples of the infrared absorber include tin oxide, antimony-doped tin oxide, indium oxide, tin oxide-doped indium oxide, lanthanum boride, lanthanum metal oxide, tungsten oxide, and inorganic carbon nanoparticles. The particle size of the particles is, for example, 5 to 200 nm. A commercially available dispersion liquid can be used for these. These can be 10 to 60 parts by weight with respect to 100 parts by weight of the siloxane oligomer represented by the formula (1) in the hard coating agent, and preferably 15 to 30 parts by weight.

  In addition, the hard coating agent according to the present invention may contain GTO gallium-doped tin oxide.

[Weather-resistant hard coat film]
In the weather resistant hard coat film according to the present invention, the UV curable hard coating agent according to the present invention is applied to a substrate. A hard coat layer is formed on the surface of the substrate by curing the applied coating agent. In addition to the hard coat layer, an ultraviolet absorbing layer, an infrared reflecting layer, and the like may be further formed by a known method.

  The substrate is preferably a transparent resin film. Examples of the transparent resin film include polyolefin resins such as polyethylene and polypropylene; polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyamide resins such as nylon-6 and nylon-66; polystyrene resins; Polyvinyl chloride resin; polyimide resin; polyvinyl alcohol resin; ethylene vinyl alcohol resin; (meth) acrylic resin; (meth) acrylonitrile resin; and cellulose resins such as triacetylcellulose, diacetylcellulose, and cellophane And is preferably a polyester-based resin.

  The weather-resistant hard coat film according to the present invention can be obtained by applying the hard coating agent according to the present invention to a substrate by a known method and then curing it by irradiating with ultraviolet rays. Since the hard coating agent according to the present invention is cured in a short time, mass production is easy.

  The weather-resistant hard coat film according to the present invention hardly forms water droplets on the hard coat layer and hardly remains as water droplets on the hard coat layer. Therefore, when the weather-resistant hard coat film according to the present invention is applied to an outdoor window or the like, the dirt on the hard coat layer is washed away by rainwater, and no water droplets remain, thus having a self-cleaning property. Therefore, the weather-resistant hard coat film according to the present invention is preferably used outdoors. Specifically, for example, it can be used for a window of a building, a window of a vehicle, and a window of an aircraft, and is particularly preferably used for a vehicle or an aircraft that moves at high speed.

[Synthesis Example 1]
70 parts by weight of ethyl silicate (ethyl silicate 48, manufactured by Colcoat), 24 parts by weight of deionized water, and 6 parts by weight of 10% paratoluenesulfonic acid in ethyl alcohol were mixed and stirred with a stirrer as an alkyl silicate. 100 parts by weight of decomposition solution was obtained. Since this hydrolyzed solution was unstable and easily gelled, it was diluted with butyl acetate to prepare a 30% solution. Next, 10 parts by weight of pentaerythritol triacrate (Biscoat # 300, manufactured by Osaka Organic Chemical Industry Co., Ltd.) and 1 part by weight of 10% dibutyltin dilaurate ethyl alcohol solution were mixed with a stirrer at 80 ° C. with stirring. Heating was performed for 1 hour to obtain Synthesis Example 1 (a compound represented by the formula (1) (n = about 10)).

[Example 1]
1 part by weight of bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide (Irgacure 819, manufactured by Ciba Japan) as a photopolymerization initiator with respect to 100 parts by weight of the solution obtained in Synthesis Example 1. As a UV absorber, 1.5 parts by weight of hydroxyphenyltriazine (Tinuvin 477, manufactured by BASF) was mixed and stirred to dissolve, and the UV curable hard coating agent according to Example 1 was obtained.

[Example 2]
30 parts by weight of colloidal silica (MIBK-ST, manufactured by Nissan Chemical Industries, Ltd.) was blended with 100 parts by weight of the hard coating agent obtained in Example 1, to obtain a UV curable hard coating agent according to Example 2.

Example 3
30 parts by weight of antimony-doped tin oxide dispersion (CV-40A, manufactured by Iida Research) was blended with 100 parts by weight of the hard coating agent obtained in Example 1 to obtain a UV curable hard coating agent according to Example 3. .

Example 4
25 parts by weight of a tungsten oxide dispersion (SII-30, manufactured by Jetchin Technology) was blended with 100 parts by weight of the hard coating agent obtained in Example 1 to obtain a UV curable hard coating agent according to Example 4. .

Example 5
30 parts by weight of an antimony-doped tin oxide dispersion (CV-40A, manufactured by Iida Research) is further blended with 100 parts by weight of the hard coating agent obtained in Example 2, and the UV curable hard coating according to Example 5 is incorporated. An agent was obtained.

Example 6
25 parts by weight of a tungsten oxide dispersion (SII-30, manufactured by Jetchin Technology) was blended with 100 parts by weight of the hard coating agent obtained in Example 2 to obtain a UV curable hard coating agent according to Example 6. .

[Comparative Example 1]
Dilution adjustment was performed by adding 50 parts by weight of toluene to 50 parts by weight of a commercially available highly weather-resistant silicon-modified acrylic resin (Acridic A871, hydroxyl value 30 mgKOH / g, manufactured by DIC) so as to obtain an appropriate coating viscosity. Next, 2 parts by weight of a benzotriazole ultraviolet absorber (Tinuvin 329FL, manufactured by Ciba Japan Co., Ltd.) was added to the liquid as an ultraviolet absorber, and the mixture was stirred and dissolved to obtain the main agent of the coating agent. 10 parts by weight of polyisocyanate (Bernock DN950) so that the isocyanate group of polyisocyanate (Bernock DN950, NCO 12%, manufactured by DIC) and the hydroxyl value of highly weather-resistant silicone-modified acrylic resin (Acridic A871) are equivalent. Was used as a curing agent. A coating agent according to Comparative Example 1 (two-component mixed coating agent) used at a mass mixing ratio of the main agent and the curing agent of 10: 1 was obtained.

[Comparative Example 2]
Comparative Example 2 is the same as Comparative Example 1 except that 70 parts by weight of the main ingredient obtained in Comparative Example 1 is further blended with 30 parts by weight of antimony-doped tin oxide dispersion (CV-40A, manufactured by Iida Research). A coating agent (two-component mixed coating agent) was obtained.

[Comparative Example 3]
A solvent-soluble fluororesin (Lumiflon LF200, hydroxyl value 30 mgKOH / g, manufactured by Asahi Glass Co., Ltd.) 50 parts by weight employed as an outdoor weather-resistant resin was diluted and adjusted by adding 50 parts by weight of toluene so as to obtain an appropriate coating viscosity. Next, 2 parts by weight of a benzotriazole ultraviolet absorber (Tinuvin 329FL, manufactured by Ciba Japan Co., Ltd.) was added to the liquid as an ultraviolet absorber, and the mixture was stirred and dissolved to obtain the main agent of the coating agent. Curing 10 parts by weight of polyisocyanate (Bernock DN950) so that the isocyanate group of polyisocyanate (Bernock DN950, NCO 12%, manufactured by DIC) and the hydroxyl value of solvent-soluble fluororesin (Lumiflon LF200) are equivalent. An agent was used. As a result, a coating agent (two-component mixed coating agent) according to Comparative Example 3 was obtained.

<Measurement>
Each of the hard coating agents of Examples 1 to 6 and the coating agents according to Comparative Examples 1 to 3 were applied to a 100 micron thick PET film (Cosmo Shine A4300, manufactured by Toyobo Co., Ltd.). The hard coating agents according to Examples 1 to 6 were dried and cured by irradiation with ultraviolet rays, and the hard coating agents according to Comparative Examples 1 to 3 were forcibly dried at 80 ° C. for 1 hour. The following measurements were performed on the hard coat film thus obtained. The results measured 7 days after curing are shown in Table 1, and the results measured after 1000 hours using an accelerated weathering tester (Super Xenon NX75, manufactured by Suga Test Instruments Co., Ltd.) are shown in Table 2.

Pencil hardness:
Using a pencil hardness measuring instrument (Epittsu Code, manufactured by Allgood Co., Ltd.), it was measured according to JIS-K5600 method.
Steel wool friction test:
Steel wool (mesh # 0000) was reciprocated 50 times on the surface of the coated film with a load of 750 g, and the surface was visually confirmed.

Solar radiation transmittance:
Using a spectrophotometer (V670, manufactured by JASCO Corporation), the solar transmittance including UV, visible light, and near infrared light was measured according to JIS A5759 method.
Color difference Delta E:
Immediately after curing, the color difference delta E after the accelerated weather resistance test was measured using a color difference meter (SE6000, manufactured by Nippon Denshoku Industries Co., Ltd.).

Water drop contact angle:
In order to measure self-cleaning properties, a water droplet contact angle serving as an index indicating the degree of hydrophilicity was measured using a water droplet contact angle meter (LCD-700S, manufactured by Kyowa Interface Chemical Co., Ltd.).

Claims (5)

A UV curable hard coating agent comprising a siloxane oligomer to which an acryloyl group represented by the following formula (1) is added, and a photopolymerization initiator.
(In the formula, n is an integer of 5 to 20.)   The UV curable hard coating agent according to claim 1, further comprising an ultraviolet absorber.   The UV curable hard coating agent according to claim 1 or 2, further comprising one or more selected from the group consisting of colloidal silica, nano silica, and nano zinc oxide powder.   The UV curable hard coating agent according to any one of claims 1 to 3, further comprising an infrared absorber. A weather-resistant hard coat film, wherein the UV curable hard coating agent according to claim 1 is applied to a substrate.