JP4069499B2 - Hard coat film or sheet - Google Patents

Description

【００２６】
ハードコート層の弾性率
以下に示す内部応力の式を用い、ハードコート層の弾性率(Ef ）を算出した。ポリエステルフィルムの弾性率(Es ）、及びポリエステルフィルム／ハードコート層から成る複合膜の弾性率（Ec）は引っ張り強度試験機を用いて、その応力- 歪み曲線の初期傾斜から求めた。但し、ハードコート層にはクラックが生じ易い為、クラックが発生する破壊歪み以下での応力- 歪み曲線を用いた。
σc(b+d)= σfd+ σsb
Ec(b+d)=Efd+Esb
∴Ef=(Ec(b+d)-Esb)/d
σc ：複合膜全体の内部応力
σf ：ハードコート層の内部応力
σs ：ポリエステルフィルムの内部応力
Ec：複合膜全体の弾性率
Ef：ハードコート層の弾性率
Es：ポリエステルフィルムの弾性率
b ：ポリエステルフィルムの厚さ
d ：ハードコート層の厚さ
【００２７】
鉛筆硬度
異なる硬度の鉛筆を用い、１K g 荷重下でJIS K5400 で示される試験法での傷の有無を判定した。
【００２８】
耐擦傷性
＃0000のスチールウールにより、ハードコート膜の表面を400gの荷重をかけながら10回摩擦し、傷の発生の有無及び傷の程度を目視により観察し、以下の判定基準に従って評価した。
A ：傷の発生が全く認められない。
B ：数本の細い傷が認められる。
C ：無数の傷が認められる。
【００２９】
＊評価結果
下記の表１にハードコート層のみの弾性率、鉛筆硬度、耐擦傷性、及びハードコート層上に導電性反射防止層を設けた形態での鉛筆硬度、耐擦傷性の評価結果を示す。
【００３０】
【表２】

【００３１】
ハードコート組成のソフト成分割合が増加するに比例してハードコート層の弾性率、鉛筆硬度、耐擦傷性が低下する。一方、ハードコート層上に機能性無機薄膜層として導電性反射防止層を設けた場合、ハードコート層の弾性率が高すぎても、低すぎても鉛筆硬度が低下し、最適な弾性率の範囲が存在する。
【００３２】
ハードコート層の弾性率が約0.5 〜5.2GPaの範囲内で最も高い鉛筆硬度を示し、特にソフト成分が20〜30% 、弾性率にして約2.8 〜4.2GPaの範囲でハードコート層の最高硬度である3Hより優れる4Hの硬度が得られた。
【００３３】
耐擦傷性はハードコート層の影響が小さく、主に無機薄膜層に依存する。導電性反射防止層上に形成された鉛筆での引っ掻き傷を顕微鏡で拡大観察すると、ハードコートの弾性率が高すぎる場合、無機薄膜層である導電性反射防止層に応力が集中し、無機薄膜層のみが表面から削り取られているように見えた。またハードコート層の弾性率が低すぎる場合には、ハードコートと無機薄膜層全体が支持体であるポリエステルフィルム表面から削り取られている。
【００３４】
一方、ハードコート層の弾性率が最適な範囲であれば、鉛筆の先端からの応力をハードコート層の変形によって分散、吸収することができ、無機薄膜層のみへの応力集中が緩和されると解釈できる。
【００３５】
【発明の効果】
上述の実施例の説明からも明らかなように、本発明による無機薄膜形成用ハードコートフィルムもしくはシート上に機能性無機薄膜層を設けることによって、表面硬度に優れる機能性フィルムを製造することができ、特にハードコート層の膜厚を変えることなく、その弾性率を特定の範囲に制御することによって、鉛筆硬度で3H〜4Hの水準を実現することができる。さらに本発明のハードコートは、表面硬度に優れる反射防止機能を持つ光学フィルムへの利用が可能である。[0001]
[Technical field to which the invention belongs]
The present invention provides a thin film composed mainly of an inorganic material having various functions such as an infrared absorption effect, an infrared reflection effect, an electromagnetic wave shielding effect, an antistatic effect, an ultraviolet absorption effect, an antireflection effect, and a reflection enhancement effect. It is related to a hard coat film or sheet to be provided on a display, especially as various display devices such as liquid crystal display devices, CRT display devices, plasma display devices, electrochromic display devices, light emitting diode display devices, EL displays. Suitable for surface functionalization of devices.
[0002]
[Prior art]
Conventionally, thin films mainly composed of inorganic materials having various functions such as infrared absorption effect, infrared reflection effect, electromagnetic wave shielding effect, antistatic effect, ultraviolet ray absorption effect, antireflection effect, reflection enhancement effect have been deposited and sputtered. It can be manufactured by forming by a dry coating process such as CVD or a wet coating process in which the above-mentioned resin composition in which functional fine particles having various effects are dispersed is applied to a plastic film, a sheet or the like. Are known. In order to give such functional films and sheets further performance such as scratch resistance, scratch resistance, chemical resistance, etc., active energy ray curable resin, thermosetting as an intermediate layer on the film and sheet base material A functional film or sheet imparted with mechanical hardness is produced by forming a hard coat layer of a mold resin or the like and providing a functional inorganic thin film thereon by a method such as vapor deposition, sputtering or coating. It has been known.
[0003]
By providing a hard coat layer between the functional inorganic thin film layer and the base film or sheet, the mechanical strength can be mainly improved. In general, a hard coat refers to one that exhibits a hardness of H or higher in the pencil hardness test shown in JIS K5400. Actually, when a plastic film or sheet is used as a support, the hard coat layer alone is 2H to 3H. It is common to indicate pencil hardness.
[0004]
[Problems to be solved by the invention]
However, even if a hard coat layer alone can achieve a pencil hardness of 2H to 3H, when a functional inorganic thin film layer is provided on the surface, insufficient adhesion between the hard coat layer and the functional inorganic thin film layer, There are many problems that hardness decreases due to poor hardness balance.
[0005]
Therefore, the present invention can control the elastic modulus within a specific range without changing the film thickness of the hard coat layer in order to produce a functional film having a surface with a functional inorganic thin film layer and excellent in surface hardness. The objective is to achieve a pencil hardness of 3H-4H. A further object of the present invention is to provide an antireflection film and sheet in which a functional film having a functional inorganic thin film layer on the surface and excellent in surface hardness has an antireflection function.
[0006]
[Means for Solving the Problems]
In order to solve this problem, the present invention provides a hard coat film in which a cured resin coating layer is provided on at least one surface of a plastic film or a sheet base material, wherein the cured resin coating layer is a trifunctional or higher polyfunctional monomer and An active energy ray-curable resin containing a urethane acrylate material is cross-linked through a processing step using ultraviolet light or electron beam irradiation, and the active energy ray-curable resin is a trifunctional or higher polyfunctional monomer and the urethane. An acrylate material is included in a weight composition ratio of 90:10 to 70:30, and an elastic modulus of the cured resin coating layer is equal to or less than a fracture strain of 2.8 GPa to 5.2 GPa. it is to Ruha over de coat film or sheet.
[0007]
Further, the film thickness of the cured resin coating layer is more than 0.5 [mu] m, a hard coat film or sheet you wherein a is 20μm or less, further wherein the cured resin coating layer is an average particle size 0.01~10μm The hard coat film or sheet according to any one of claims 1 to 3, wherein the hard coat film or sheet contains inorganic or organic fine particles, or has a concavo-convex surface .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail. First, the constituent material of the hard coat film or sheet for forming an inorganic thin film will be described, and then the manufacturing method will be described.
[0010]
The transparent plastic film or sheet used in the present invention is not particularly limited, and can be appropriately selected from known transparent plastic films or sheets. Specific examples include polyester, polyethylene, polypropylene, cellophane, triacetyl cellulose, diacetyl cellulose, acetyl cellulose butyrate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene vinyl alcohol, polystyrene, polycarbonate, polymethylpentene, polysulfone. , Polyether ether ketone, acrylic, nylon, fluorine resin, polyimide, polyether imide, polyether sulfone, and the like. In the present invention, particularly triacetyl cellulose film and uniaxially stretched polyester are used. In addition to being excellent in transparency, it is preferable in that there is no optical anisotropy.
[0011]
For the cured resin coating layer, it is particularly preferable to use an active energy ray-curable resin because of its high processing speed and low thermal damage to the support. The active energy ray-curable resin is not particularly limited, and any resin can be used as long as it provides a coating film having a pencil hardness of H 2 or more by ultraviolet ray or electron beam curing. Examples of such ultraviolet curable resins are synthesized from polyfunctional acrylate resins such as acrylic acid or methacrylic acid ester of polyhydric alcohol, diisocyanate, polyhydric alcohol and hydroxyalkyl ester of acrylic acid or methacrylic acid. Such polyfunctional urethane acrylate resins can be mentioned. Furthermore, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins and the like can be suitably used as necessary.
[0012]
Reactive diluents for these resins include 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, hexanediol (meta ) Bifunctional or higher monomers and oligomers such as acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, neopentyl glycol di (meth) acrylate, and monofunctional monomers For example, acrylic esters such as N-vinyl pyrrolidone, ethyl acrylate, propyl acrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate , Hexyl methacrylate, isooctyl methacrylate, methacrylic acid esters such as 2-hydroxyethyl methacrylate, cyclohexyl methacrylate, nonylphenyl methacrylate, tetrahydrofurfuryl methacrylate, and its caprolactone derivatives, styrene, α-methylstyrene, acrylic Acids and the like and mixtures thereof can be used.
[0013]
In the present invention, when the active energy ray is ultraviolet light, it is necessary to add a photosensitizer (radical polymerization initiator), such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzyl methyl. Benzoins such as ketals and their alkyl ethers; acetophenones such as acetophenone, 2,2, -dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone; methyl anthraquinone, 2-ethylanthraquinone, 2-amylanthraquinone, etc. Anthraquinones; thioxanthones such as thioxanthone, 2,4-diethylthioxanthone, and 2,4-diisopropylthioxanthone; ketones such as acetophenone dimethyl ketal and benzyl dimethyl ketal Benzophenones such as benzophenone and 4,4-bismethylaminobenzophenone and azo compounds. These can be used alone or as a mixture of two or more thereof, and further, tertiary amines such as triethanolamine and methyldiethanolamine; benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and 4-dimethylaminoethylethylbenzoate, etc. It can be used in combination with a photoinitiator aid or the like. The usage-amount of an organic peroxide and a photoinitiator is 0.5-20 weight part with respect to 100 weight part of polymeric components of the said resin composition, Preferably it is 1-15 weight part.
[0014]
In addition, as an optical function by forming irregularities on the hard coat layer surface, if you want to obtain an antiglare effect, make the hard coat agent contain inorganic or organic fine particles, or form irregularities on the surface by embossing You can reach your goals.
[0015]
In particular, inorganic or organic fine particles can be arbitrarily used as long as they maintain fine transparency in the active energy ray-curable resin.
[0016]
In general, fine particles made of silica, alumina, titania, zirconia, etc. are used as the inorganic fine particles. Among them, silica particles, particularly synthetic silica particles are preferable in terms of antiglare properties, resolution, hard coat properties and the like. . Conductive transparent fine particles such as tin oxide, indium oxide, cadmium oxide, and antimony oxide can also be used regardless of imparting antistatic properties.
[0017]
Further, as the organic fine particles, hard fine particles that have an appropriate crosslinking structure inside the particles and do not swell due to an active energy ray-curable resin, a monomer, a solvent, or the like can be used. For example, particle internal cross-linked styrene resin, styrene-acrylic copolymer resin, acrylic resin, divinylbenzene resin, silicone resin, urethane resin, melamine resin, styrene-isoprene resin, benzoguanamine resin, other reactive microgels Etc. can be used. The blending amount of the transparent fine particles is 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight per 100 parts by weight of the active energy ray-curable resin.
[0018]
Moreover, a well-known general coating additive can be mix | blended as needed. For example, silicone-based and fluorine-based additives that impart leveling, surface slip properties, etc. are effective in preventing scratches on the surface of the cured film, and when using ultraviolet rays as active energy rays, the additive air Bleeding to the interface can reduce the inhibition of curing of the resin by oxygen, and an effective degree of curing can be obtained even under low irradiation intensity conditions. Appropriate amounts of these additives are 0.01 to 0.5 parts by weight per 100 parts by weight of the active energy ray-curable resin.
[0019]
Although the main constituent materials that can be used in the present invention have been described above, a method for producing a hard coat film or sheet for forming an inorganic thin film will be specifically described. The method for applying the hard coat layer is arbitrary, but in the production stage, a roll coater, a reverse roll coater, a gravure coater, a knife coater, a bar coater or the like is generally used. When ultraviolet rays are used as an active energy ray source, light sources such as high pressure mercury lamp, low pressure mercury lamp, ultra high pressure mercury lamp, metal halide lamp, carbon arc, xenon arc, etc. can be used. A metal halide lamp is generally used when a filler is included or a thick film is cured. In the case of curing using an electron beam, it is emitted from various electron beam accelerators such as a Cockloftwald type, a bandecraft type, a resonant transformation type, an insulating core transformer type, a linear type, a dynamitron type, and a high frequency type. An electron beam having an energy of ˜1000 KeV, preferably 100 to 300 KeV can be used.
[0020]
【Example】
Next, the present invention will be specifically described with reference to examples.
<Example 1>
EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Parts and% are based on weight unless otherwise specified.
[0021]
* Hard coat layer Compared to the electron beam curable resin composition consisting of the hard components shown below, the soft component that is also an electron beam curable resin is 0%, 10%, 20%, 30%, 60% by weight composition ratio. , 100%, and a coating composition prepared by adding 2-butanone so that the resin solid content was 70 wt% was used as a hard coating agent.
(Hard ingredients)
・ Pentaerythritol triacrylate 4 parts by weight ・ Trimethylolpropane triacrylate 1 part by weight (soft component)
・ Urethane acrylate oligomer (NK Oligo U-1084A, Shin-Nakamura Chemical Co., Ltd.)
[0022]
Next, the electron beam curable hard coat agent was applied to one side of a 150 μm-thick double-sided easily-adhesive polyester film with a wire bar to evaporate the solvent, thereby forming a coating layer having a thickness of about 5 μm. Thereafter, a hard coat resin layer was prepared by curing an electron beam with an acceleration voltage of 200 KeV from the coating film side under the condition of an absorbed dose of 3 Mrad. The adhesion between the polyester film and the hard coat layer was good.
[0023]
* Inorganic thin film layer As a specific example of the functional inorganic thin film layer, a conductive antireflection layer was formed on the hard coat layer by the following constitution and method. First, indium tin oxide (ITO) was formed as a high refractive index layer by a sputtering method, and an antireflection layer made of silicon oxide was formed by a plasma assisted deposition method as a low refractive index layer. The refractive index n, shape film thickness d, and optical film thickness nd of each layer are
PET film (n = 1.62)
Hard coat layer (n = 1.52 d = about 5 μm)
First layer: ITO (nH = 0.25 d = about 58 nm)
Second layer: SiO2 (nL = 1.46 d = about 38 nm)
3rd layer: ITO (nH = 2.05 d = approx. 125nm)
Fourth layer: SiO2 (nL = 1.46 d = about 140 nm)
It was. However, nH is a high refractive index and nL is a low refractive index. The optical film thickness was monitored by an optical film thickness monitor, and when the target light quantity value was reached, the film formation was stopped and a predetermined optical film thickness was obtained. The reflectance was 1% or less in the wavelength range of 430 to 680 nm. The adhesion between the hard coat layer and the conductive antireflection layer was good.
[0024]
* Evaluation Method For the conductive antireflection film obtained by the above method, the mechanical properties were measured by the following measurement method, and the evaluation results are shown in Table 1 below.
[0025]
[Table 1]

[0026]
The elastic modulus (Ef) of the hard coat layer was calculated using the internal stress formula shown below. The elastic modulus (Es) of the polyester film and the elastic modulus (Ec) of the composite film composed of the polyester film / hard coat layer were determined from the initial slope of the stress-strain curve using a tensile strength tester. However, since cracks are likely to occur in the hard coat layer, a stress-strain curve below the fracture strain at which cracks occur was used.
σc (b + d) = σfd + σsb
Ec (b + d) = Efd + Esb
∴Ef = (Ec (b + d) -Esb) / d
σc: Internal stress of the entire composite film σf: Internal stress of the hard coat layer σs: Internal stress of the polyester film
Ec: Elastic modulus of the entire composite membrane
Ef: Elastic modulus of hard coat layer
Es: Elastic modulus of polyester film
b: Polyester film thickness
d: Hard coat layer thickness [0027]
Pencil hardness Using pencils with different hardnesses, the presence or absence of scratches in the test method shown in JIS K5400 was determined under a 1 kg load.
[0028]
The surface of the hard coat film was rubbed 10 times with a steel wool of scratch resistance # 0000 while applying a load of 400 g, and the presence or absence of scratches and the extent of the scratches were visually observed and evaluated according to the following criteria.
A: No scratches are observed.
B: Several thin scratches are observed.
C: Countless scratches are recognized.
[0029]
* Evaluation results Table 1 below shows the evaluation results of the elastic modulus, pencil hardness, and scratch resistance of only the hard coat layer, and the pencil hardness and scratch resistance in a form in which a conductive antireflection layer is provided on the hard coat layer. Show.
[0030]
[Table 2]

[0031]
As the soft component ratio of the hard coat composition increases, the elastic modulus, pencil hardness, and scratch resistance of the hard coat layer decrease. On the other hand, when a conductive antireflection layer is provided as a functional inorganic thin film layer on the hard coat layer, the pencil hardness decreases even if the elastic modulus of the hard coat layer is too high or too low. A range exists.
[0032]
The hard coat layer exhibits the highest pencil hardness in the range of about 0.5 to 5.2 GPa, especially the soft component is 20 to 30%, and the maximum hardness of the hard coat layer is in the range of about 2.8 to 4.2 GPa. A hardness of 4H, which is better than 3H, was obtained.
[0033]
The scratch resistance is less affected by the hard coat layer and mainly depends on the inorganic thin film layer. When the scratches with a pencil formed on the conductive antireflection layer are observed with a microscope, if the elastic modulus of the hard coat is too high, stress concentrates on the conductive antireflection layer, which is an inorganic thin film layer, and the inorganic thin film Only the layer appeared to be scraped off the surface. When the elastic modulus of the hard coat layer is too low, the entire hard coat and the inorganic thin film layer are scraped from the surface of the polyester film as the support.
[0034]
On the other hand, if the elastic modulus of the hard coat layer is in the optimum range, the stress from the tip of the pencil can be dispersed and absorbed by the deformation of the hard coat layer, and the stress concentration only on the inorganic thin film layer is relieved. Can be interpreted.
[0035]
【The invention's effect】
As is clear from the description of the above-described Examples, a functional film having excellent surface hardness can be produced by providing a functional inorganic thin film layer on a hard coat film or sheet for forming an inorganic thin film according to the present invention. In particular, a pencil hardness of 3H to 4H can be achieved by controlling the elastic modulus within a specific range without changing the film thickness of the hard coat layer. Furthermore, the hard coat of the present invention can be used for an optical film having an antireflection function excellent in surface hardness.

Claims (3)

A hard coat film provided with a cured resin coating layer on at least one surface of a plastic film or a sheet substrate,
The cured resin coating layer is obtained by cross-linking an active energy ray-curable resin containing a trifunctional or higher polyfunctional monomer and a urethane acrylate material through a processing step by ultraviolet ray or electron beam irradiation, and
The active energy ray-curable resin contains the polyfunctional monomer having three or more functional groups and the urethane acrylate material in a weight composition ratio of 90:10 to 70:30, and
A hard coat film, wherein an elastic modulus of the cured resin coating layer below a fracture strain is in a range of 2.8 GPa to 5.2 GPa. The hard coat film or sheet according to claim 1, wherein the thickness of the cured resin coating layer is 0.5 μm or more and 20 μm or less. The hard coat film according to claim 1 or claim 2, wherein the cured resin coating layer contains an inorganic or organic fine particles having an average particle diameter of 0.01 to 10 [mu] m, or surface, characterized in that has a concave-convex shape Or a sheet.