JP2016187870A - Hard coat film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard coat film which is formed by providing a hard coat layer on at least one surface of a cycloolefin film via an easy-to-adhere layer and is excellent in adhesiveness with time under ordinary conditions and under moisture- and heat-resistant conditions and causes no occurrence of cracking under heat resistant conditions.SOLUTION: There is provided a hard coat film 10 formed by providing a hard coat layer 3 on at least one surface of a cycloolefin film 1 via an easy-to-adhere layer 2. The easy-to-adhere layer 2 contains a mixture of a polyolefin-based resin and a methyl methacrylate-based resin and the blending ratio (pts.wt.) of the polyolefin-based resin and the methyl methacrylate-based resin is, for example, in the range of 90/10 to 40/60. In addition, the hard coat layer 3 contains an ionizing radiation curable resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hard coat film, and more specifically, flat panel displays such as liquid crystal display devices, plasma display devices and electroluminescence (EL) display devices, display device parts such as touch panels, and buildings, automobiles, and train windows. The present invention relates to a hard coat film in which a hard coat layer is provided via an easy-adhesion layer on a cycloolefin film that can be used as a protective film such as glass.

  A display surface of a flood panel display such as a liquid crystal display device (LCD) is required to be provided with scratch resistance so that the surface is not damaged due to scratches during handling. Therefore, it is generally performed to impart scratch resistance using a hard coat film in which a hard coat layer is provided on a base film. In recent years, with the spread of touch panels that can input data and instructions by touching with a finger, pen, etc. while viewing the display on the display screen, functional requirements for hard coat film having optical visibility maintenance and scratch resistance are It is growing.

Therefore, a cycloolefin film excellent in transparency, heat resistance, dimensional stability, low hygroscopicity, low birefringence, and optical isotropy as a base film is expected to be used for optical member applications. A hard coat layer is provided on a cycloolefin film. However, unlike an acrylic film or a polyester film, the cycloolefin film has a problem in that the adhesion between the base film and the hard coat layer is poor because the number of polar groups on the film surface is small.
Therefore, conventionally, methods for imparting easy adhesion with a hard coat layer to a cycloolefin film are disclosed in Patent Document 1, Patent Document 2, and the like.

JP 2001-147304 A JP 2006-110875 A

  Conventionally, Patent Document 1 discloses corona treatment, plasma treatment, UV treatment, and the like as methods for imparting easy adhesion with a hard coat layer to a cycloolefin film. Adhesion with the hard coat layer is insufficient, and there is a problem that adhesion failure with time tends to occur.

  Patent Document 2 discloses that an anchor coating agent made of an olefin resin is coated on a cycloolefin film. This anchor coat treatment improves the adhesion between the cycloolefin film and the hard coat layer to some extent, but the anchor coat layer is inferior in solvent resistance, so when forming the hard coat layer on the anchor coat layer, the anchor coat layer However, there is a problem in that the adhesion of the hard coat layer is inferior due to erosion by the solvent in the hard coat agent. In addition, in the anchor coat layer where the coating film is flexible and stretched and the hard coat layer where the coating film is hard and does not stretch, both coating films shrink under heat resistant conditions (for example, stored in a dryer at a temperature of 100 ° C. for 5 minutes). Due to the difference, there was a problem that cracks (film cracks, cracks, etc.) were likely to occur on the hard coat layer surface.

  Therefore, in the conventional hard coat film, it is difficult to achieve both adhesion (particularly adhesion over time) with the hard coat layer when using a cycloolefin film as a base material and prevention of crack generation under heat resistant conditions, which is a problem. It was.

  Accordingly, the present invention is a hard coat film in which a hard coat layer is provided on at least one surface of a cycloolefin film via an easy-adhesion layer, and has excellent temporal adhesion under normal conditions and moist heat resistance, and is heat resistant. An object is to provide a hard coat film free from cracking under conditions.

As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by having the following configuration.
That is, the present invention has the following configuration.
A first invention is a hard coat film in which a hard coat layer is provided on at least one surface of a cycloolefin film via an easy adhesion layer, and the easy adhesion layer is a mixture of a polyolefin resin and a methyl methacrylate resin. And the hard coat layer contains an ionizing radiation curable resin.

  Moreover, 2nd invention is the said 1st invention. WHEREIN: The compounding ratio (weight part) of the said polyolefin resin and the said methylmethacrylate resin in the said easily bonding layer is in the range of 90 / 10-40 / 60. It is a hard coat film characterized by being.

  The third invention is the hard coat film according to the first or second invention, wherein the methyl methacrylate resin has a glass transition point of 90 degrees or more.

  Moreover, 4th invention contains the polyfunctional acrylate which has 3 or more (meth) acryloyloxy groups in 1 molecule in said 1st thru | or 3rd invention in said invention. It is a hard coat film characterized by doing.

  The fifth invention is the hard coat film according to any one of the first to fourth inventions, wherein the easy-adhesion layer has a thickness in the range of 0.1 μm to 1.0 μm. .

  According to the present invention, there is provided a hard coat film in which a hard coat layer is provided on at least one surface of a cycloolefin film via an easy-adhesion layer, which has excellent adhesion over time under normal conditions and moist heat resistance, and is heat resistant. A hard coat film free from cracking under conditions can be obtained.

It is sectional drawing which shows the layer structure of one Embodiment of the hard coat film which concerns on this invention.

Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not necessarily limited to the following embodiment.
As shown in FIG. 1, the layer constitution of the hard coat film 10 of one embodiment of the present invention is such that the hard coat layer 3 is provided on at least one surface of a cycloolefin film 1 as a base film via an easy adhesion layer 2. Is provided. The easy adhesion layer 2 contains a mixture of a polyolefin resin and a methyl methacrylate resin, and a hard coat layer 3 containing an ionizing radiation curable resin is formed on the easy adhesion layer 2.

[Base film]
First, the base film of the hard coat film will be described.
In the present invention, as the base film of the hard coat film 10, a cycloolefin film excellent in transparency, heat resistance, dimensional stability, low hygroscopicity, low birefringence, optical isotropy, and the like is used. Features. Specifically, cycloolefin units are polymerized alternately or randomly in the polymer skeleton and have an alicyclic structure in the molecular structure, and include norbornene compounds, monocyclic cyclic olefins, cyclic conjugated dienes and vinyl fatty acids. A cycloolefin copolymer film or a cycloolefin polymer film, which is a (co) polymer comprising at least one compound selected from cyclic hydrocarbons, is selected and used as appropriate. Also, in selecting a cycloolefin film, the cycloolefin copolymer film is slightly inferior in hygroscopicity to the cycloolefin polymer film, but has excellent adhesion to other component resins because it has a polar group on the surface of the substrate. Therefore, it is necessary to select according to the purpose of the product.

  Moreover, in this invention, although the thickness of the said cycloolefin film 1 is suitably selected according to the use for which a hard coat film is used, from the viewpoint of mechanical strength, handling property, etc., in the range of 10 micrometers-300 micrometers. It is preferable that it is in the range of 20 μm to 200 μm.

  In the present invention, when the heat resistance of the cycloolefin film 1 is used for a hard coat film, a thermogravimetry (TG) method for measuring a thermal change when a temperature change is applied to a sample or a differential scanning calorific value. The use of a film having a glass transition temperature measured by a measurement (DSC) method or the like of about 120 ° C. to 170 ° C. is preferred.

  In the present invention, when the cycloolefin film 1 is used for a hard coat film, a resin obtained by kneading a cycloolefin resin and an ultraviolet absorber is used in the form of a film for the purpose of preventing coating film deterioration and adhesion failure due to ultraviolet rays. Alternatively, a film or a film obtained by coating a cycloolefin film with one or both surfaces coated with a thermoplastic or thermosetting resin and an ultraviolet absorber may be used. As for the UV-cutting property, the transmittance at a wavelength of 380 nm as measured by a spectrophotometer is preferably 10% or less. More preferably, it is 7% or less.

[Easily adhesive layer]
Next, the said easily bonding layer 2 is demonstrated.
In the present invention, the easy-adhesion layer 2 needs to contain a mixture of a polyolefin resin and a methyl methacrylate resin.

  In the present invention, the polyolefin resin constituting the easy-adhesion layer 2 is a resin blended for the purpose of imparting adhesion between the cycloolefin film 1 and the hard coat layer 3. As a result of intensive studies on the resin for an easy adhesion layer having excellent adhesion to both the cycloolefin film 1 and the hard coat layer 3, the present inventors have found that a polyolefin-based resin having excellent flexibility is suitable.

  The polyolefin resin used for the easy-adhesion layer 2 in the present invention is not particularly limited, but examples of the resin having excellent adhesion to the substrate include 2 such as ethylene-propylene copolymer and propylene-butene copolymer. Those constituting the copolymer with more than one type of monomer are preferred, and those containing a propylene monomer in the copolymer are particularly preferred. The molecular weight is not particularly limited, but those having a weight average molecular weight in the range of 10,000 to 200,000 are preferable from the viewpoint of the balance between flexibility and adhesion. Examples of such polyolefin resins include commercially available Unistor (trade name: manufactured by Mitsui Chemicals), Surflen (trade name: manufactured by Mitsubishi Chemical), and Auroren (trade name: Nippon Paper Industries Co., Ltd.). Manufactured) and the like.

  In addition, since this polyolefin-type resin is resin excellent in a softness | flexibility, there exists a problem which is easy to crimp | bond when forming an easily bonding layer and winding up a film. Therefore, it is preferable to prevent pressure-bonding by adding a high hardness resin, inorganic or organic fine particles to the easy-adhesion layer, or attaching a protective film to the back surface of the cycloolefin film from the viewpoint of preventing blocking between films.

  In the blending of inorganic or organic fine particles, the blending amount (parts by weight) is in the range of resin / inorganic or organic fine particles forming the easy-adhesion layer 2 = 99.8 / 0.2 to 95.0 / 5.0. It is preferable. When the blending amount of the fine particles exceeds 5.0 parts by weight, it is not preferable because the transparency and the adhesion to the cycloolefin film are lowered. On the other hand, there is a concern that a sufficient effect is not exhibited when the amount of the fine particles is less than 0.2 parts by weight.

  Examples of inorganic fine particles include fine particles such as alumina, zinc oxide, silica, titanium oxide, and cerium oxide. Examples of organic fine particles include fine particles such as acrylic, melamine / formaldehyde condensate, polyethylene, styrene acrylic, and polyester. It can be illustrated. As the particle size, for example, it is preferable to use fine particles of 0.05 μm to 0.20 μm. A particle diameter of less than 0.05 μm is not preferable because the effect of preventing pressure bonding is low. On the other hand, if the particle diameter exceeds 0.20 μm, the effect of preventing further press-bonding cannot be obtained, resulting in an increase in cost, an increase in external haze, and a decrease in transparency, which is not preferable.

In the present invention, the easy adhesion layer 2 further contains a methyl methacrylate resin. The main performance required for the easy-adhesion layer is that it is not eroded by the solvent in the hard coat agent applied to the surface and has excellent adhesion to the hard coat layer 3, and heat with the hard coat layer 3. It is required to reduce the shrinkage difference and prevent the occurrence of cracks under heat resistant conditions. In particular, regarding cracks, in order to ensure the adhesion between the cycloolefin film substrate 1 and the hard coat layer 3, the use of a polyolefin-based resin is effective, but the coating film is a resin that is flexible and has a large elongation. Therefore, the coating film is hard and has a large shrinkage difference from the hard coat layer 3 with little elongation, and cracks are likely to occur. In order to prevent such cracks, it is essential to suppress the elongation of the easy-adhesion layer 2, and it is necessary to add a hardened resin having good compatibility with the polyolefin resin. As those satisfying such required performance, that is, excellent in hardness, heat resistance, solvent resistance, and compatibility with polyolefin resins, methyl methacrylate resins can be preferably used in the present invention. Among these methyl methacrylate resins, those having particularly excellent hardness and heat resistance are preferably those having a glass transition temperature of 90 ° C. or higher, and particularly preferably those having a glass transition temperature of 100 ° C. or higher. The upper limit temperature of the glass transition temperature is usually determined by the compound characteristics, but is usually desirably 120 degrees or less. In the present invention, a glass transition temperature of about 105 ° C. can be preferably used. The glass transition temperature is measured by a thermogravimetry (TG) method, a differential scanning calorimetry (DSC) method, or the like.
Specific examples of the methyl methacrylate resin used in the present invention include, for example, a commercially available thermolac resin (trade name: manufactured by Soken Chemical Co., Ltd.), acrylate resin (trade name: manufactured by Taisei Fine Chemical Co., Ltd.), diamond Nal resin (trade name: manufactured by Mitsubishi Rayon Co., Ltd.) and the like.

In the present invention, the blending ratio (parts by weight) of the polyolefin resin and the methyl methacrylate resin contained in the easy-adhesion layer 2 is desirably in the range of 90/10 to 40/60.
If the blending ratio of the polyolefin-based resin exceeds 90 parts by weight, the easily adhesive layer that is formed is soft and easily stretched. Therefore, due to the difference in shrinkage from the hard coat layer that does not stretch hard, it is stored at 100 ° C. for 5 minutes ), Cracks are likely to occur, scratch resistance is reduced, and when a hard coat layer is formed on the easy-adhesion layer, the easy-adhesion layer is eroded by the solvent in the hard coat agent, and the adhesion of the hard coat layer is reduced. There is a problem that the coating film hardness (pencil hardness) tends to decrease. On the other hand, when the blending ratio of the polyolefin resin is less than 40 parts by weight, the difference in shrinkage between the easy-adhesion layer and the hard coat layer is small and cracks are not generated under heat resistant conditions. There is a problem that the adhesion with the film is lowered.

  Further, the coating thickness of the easy-adhesion layer 2 is not particularly limited, but is 0 in a range that does not adversely affect the adhesion between the cycloolefin film and the hard coat layer or the pencil hardness of the hard coat layer. It is desirable that the thickness is 1 μm to 1.0 μm, and more desirably 0.2 μm to 0.6 μm. If the thickness of the easy-adhesion layer 2 is less than 0.1 μm, the adhesion with the hard coat layer is lowered, which is not preferable. On the other hand, when the thickness of the easy-adhesion layer 2 exceeds 1.0 μm, an easy-adhesion layer having low hardness is formed in the lower layer of the hard coat layer, and the pencil hardness of the hard coat film is reduced (for example, hardness H To hardness HB), and cracks are likely to occur under heat resistant conditions.

  The easy-adhesion layer 2 can be blended with a leveling agent for the purpose of improving coatability. For example, a known leveling agent such as a fluorine-based, acrylic-based, siloxane-based, or an adduct or mixture thereof is used. Is possible. The blending amount can be, for example, in the range of 0.03 to 3.0 parts by weight with respect to 100 parts by weight of the resin component of the easy-adhesion layer.

  The easy-adhesion layer 2 can be blended with a benzotriazole-based UV absorber or a benzophenone-based UV absorber for the purpose of imparting light-resistant adhesion. The blending amount is preferably 0.05 to 10.0 parts by weight with respect to 100 parts by weight of the resin component of the easy-adhesion layer. Particularly preferred is 1.0 to 5.0 parts by weight.

  Further, as other additives to be added to the easy-adhesion layer 2, an antifoaming agent, an antifouling agent, an antioxidant, an antistatic agent, a light stabilizer, and the like are required as long as the effects of the present invention are not impaired. May be blended.

  In the present invention, the easy-adhesion layer 2 is coated on the cycloolefin film 1 with a paint obtained by dissolving and dispersing other additives in an appropriate organic solvent in addition to the polyolefin resin and the methyl methacrylate resin. Processed, dried, or then cured and formed. The organic solvent in this case can be appropriately selected according to the solubility of the resin contained therein, and is a solvent that can uniformly dissolve or disperse at least a solid content (resin and other additives), and at the time of coating. The use of an organic solvent having a boiling point of 50 ° C. to 160 ° C. is preferred from the viewpoints of workability and drying properties. Examples of such solvents include aromatic solvents such as toluene, xylene and n-heptane, aliphatic solvents such as cyclohexane, methylcyclohexane and ethylcyclohexane, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and acetic acid. Known organic solvents such as ester solvents such as butyl and methyl lactate, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, and alcohol solvents such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol and butanol These can be used alone or in appropriate combinations of several kinds.

  In the present invention, the method for applying the coating material for the easy adhesion layer onto the cycloolefin film 1 includes gravure coating, microgravure coating, fountain bar coating, slide die coating, slot die coating, and screen printing. It can be applied by a known coating method such as a spray coating method. The paint applied on the cycloolefin film 1 is usually dried at a temperature of about 50 to 120 ° C. to remove the solvent, and then cured by applying external energy such as heat energy or ultraviolet rays or electron beams to form a coating film. Form.

[Hard coat layer]
Next, the hard coat layer 3 will be described.
In the present invention, the resin contained in the hard coat layer 3 can be used without particular limitation as long as it is a resin that forms a film, but particularly provides the surface hardness (pencil hardness, scratch resistance) of the hard coat layer. In addition, it is preferable to use an ionizing radiation curable resin in that the degree of crosslinking can be adjusted by the exposure amount of ultraviolet rays, and the surface hardness of the hard coat layer can be adjusted.

  The ionizing radiation curable resin used in the present invention is a transparent resin that is cured by irradiation with ultraviolet rays (hereinafter abbreviated as “UV”) or electron beams (hereinafter abbreviated as “EB”). Although not particularly limited, UV or EB having three or more (meth) acryloyloxy groups in one molecule in order for the coating film hardness and the hard coat layer 3 to form a three-dimensional cross-linked structure. It is preferable to use a polyfunctional acrylate which can be cured. Specific examples of UV or EB curable polyfunctional acrylate having 3 or more (meth) acryloyloxy groups in the molecule include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (Meth) acrylate, dipentaerythritol tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, trimethylolpropane ethoxytriacrylate, glycerin propoxy Examples include triacrylate and ditrimethylolpropane tetraacrylate. A plurality of polyfunctional acrylates may be mixed.

  Moreover, as resin contained in the said hard-coat layer 3, other than the above-mentioned ionizing radiation curable resin, thermoplastic resins, such as polyethylene, a polypropylene, a polystyrene, a polycarbonate, polyester, an acryl, styrene-acryl, a fiber, You may mix | blend thermosetting resins, such as a phenol resin, urea resin, unsaturated polyester, an epoxy, and a silicon resin, in the range which does not impair the hardness of a hard-coat layer, and scratch resistance.

  In addition, as a photopolymerization initiator of the ionizing radiation curable resin contained in the hard coat layer 3, acetophenones such as commercially available IRGACURE 651 and IRGACURE 184 (both are trade names: manufactured by BASF), IRGACURE 500 ( Benzophenones such as trade name: BASF) can be used.

  In the present invention, the hard coat layer 3 may contain inorganic oxide fine particles to further improve the surface hardness (scratch resistance). In this case, the average particle diameter of the inorganic oxide fine particles is preferably in the range of 5 to 50 nm, more preferably in the range of 10 to 20 nm. If the average particle size is less than 5 nm, it is difficult to obtain sufficient surface hardness. On the other hand, when the average particle diameter exceeds 50 nm, the gloss and transparency of the hard coat layer are lowered, and the flexibility may be lowered.

  In the present invention, examples of the inorganic oxide fine particles include alumina and silica. Among these, alumina containing aluminum as a main component is particularly suitable because it has a high hardness and can obtain an effect with a smaller amount of addition than silica.

  In the present invention, the content of the inorganic oxide fine particles is preferably 0.1 to 10.0 parts by weight with respect to 100 parts by weight of the solid content of the hard coat layer coating composition. When the content of the inorganic oxide fine particles is less than 0.1 parts by weight, it is difficult to obtain an effect of improving the surface hardness (abrasion resistance). On the other hand, if the content exceeds 10.0 parts by weight, the haze increases, which is not preferable.

For the hard coat layer 3, a leveling agent can be used for the purpose of improving coatability. For example, a known leveling agent such as fluorine-based, acrylic-based, siloxane-based, or an adduct or mixture thereof is used. Is possible. The blending amount can be in the range of 0.03 to 3.0 parts by weight with respect to 100 parts by weight of the solid content of the resin of the hard coat layer. In touch panel applications, when adhesion to the cover glass (CG), transparent conductive member (TSP), liquid crystal module (LCM), etc. of the touch panel terminal is required using an optical transparent resin OCR. Is preferably an acrylic leveling agent or a fluorine leveling agent having a high surface free energy (approximately 40 mJ / cm ² or more).

  As other additives to be added to the hard coat layer 3, as long as the effects of the present invention are not impaired, an antifoaming agent, a surface tension adjusting agent, an antifouling agent, an antioxidant, an antistatic agent, an ultraviolet absorber, light You may mix | blend a stabilizer etc. as needed.

  The hard coat layer 3 is formed by applying and drying a paint obtained by dissolving and dispersing a polymerization initiator, other additives and the like in an appropriate solvent in addition to the ionizing radiation curable resin. Formed. The solvent can be appropriately selected depending on the solubility of the resin to be blended, and may be any solvent that can uniformly dissolve or disperse at least solids (resin, polymerization initiator, and other additives). Examples of such solvents include aromatic solvents such as toluene, xylene and n-heptane, aliphatic solvents such as cyclohexane, methylcyclohexane and ethylcyclohexane, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate and acetic acid. A known organic solvent such as an ester solvent such as butyl or methyl lactate, a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone, or an alcohol solvent such as methanol, ethanol, isopropyl alcohol, or n-propyl alcohol. Or it can also be used in combination of several kinds as appropriate.

  The coating method of the hard coat layer 3 is not particularly limited, but gravure coating, micro gravure coating, fountain bar coating, slide die coating, slot die coating, screen printing method, spray coating method, etc. After coating by the known coating method, it is usually dried at a temperature of about 50 to 120 ° C.

  The coating thickness of the hard coat layer 3 is not particularly limited, but is preferably in the range of 1.0 μm to 12.0 μm, for example. If the coating thickness is less than 1.0 μm, it is difficult to obtain the required surface hardness. On the other hand, when the coating thickness exceeds 12.0 μm, curling is strongly generated, and handling properties are reduced in the manufacturing process and the like, which is not preferable. The coating thickness of the hard coat layer 3 can be measured by actually measuring with a micrometer.

  In the present invention, the hard coat layer coating containing the ionizing radiation curable resin is applied to a cycloolefin film having an easy-adhesion layer, dried, and then irradiated with UV or EB to cause photopolymerization and hard properties. Can be obtained. In particular, a hard coat layer having a pencil hardness of B to 2H specified in JIS K5600-5-4 is preferable.

  As described in detail above, the hard coat film of the present invention is provided with a hard coat layer on at least one side of the cycloolefin film via an easy-adhesion layer, and the easy-adhesion layer comprises a polyolefin resin and a methyl methacrylate resin. By containing the mixture, the adhesion between the cycloolefin film and the hard coat layer can be improved, and in particular, the adhesion over time under normal conditions and heat-and-moisture resistance conditions is excellent. Moreover, even when it preserve | saves on heat resistant conditions by reducing the shrinkage | contraction difference of an easily bonding layer and a hard-coat layer, generation | occurrence | production of a crack can be prevented.

EXAMPLES Next, although an Example and a comparative example are given and this invention is explained in full detail concretely, this invention is not limited to a following example.
Unless otherwise specified, “parts” and “%” described below represent “parts by weight” and “% by weight”, respectively.

[Example 1]
<Preparation of easy adhesion layer paint>
First, 70 parts of polyolefin-based resin “Surflen P-1000 (trade name)” (solid content 20%, manufactured by Mitsubishi Chemical Corporation) and the above-mentioned methyl methacrylate-based resin “thermolac LP45M30 (trade name)” (solid content 30 %, Manufactured by Soken Chemical Co., Ltd.), and the solid content is butyl acetate / toluene = 85/15 (% by weight) until the solid content ratio of the polyolefin resin and the methyl methacrylate resin is 70/30. An easy-adhesion layer coating material was prepared by diluting to a concentration of 7%.

<Preparation of hard coat layer paint>
Urgyl acrylate UV curable resin "Shikou UV-7630B (trade name)" (solid content 100%, (meth) acryloyloxy group number: 6, manufactured by Nippon Synthetic Chemical Co., Ltd.) 100 parts, Irgacure 184 (photopolymerization) 3.5 parts of initiator, manufactured by BASF, 2.5 parts of hindered amine light stabilizer “TINUVIN 292 (trade name)” (manufactured by BASF), and leveling agent RS75 (fluorine leveling agent, DIC Corporation) (Manufactured) 0.3 parts diluted with butyl acetate / n-propyl alcohol = 50/50 (parts by weight) until the solid content concentration in the paint of the UV curable resin is 45% and stirred sufficiently to hard coat layer paint Was prepared.

<Preparation of hard coat film>
Apply the above-mentioned easy-adhesion layer paint using a bar coater on one side of a ZEONOR film ZF14 (manufactured by Nippon Zeon Co., Ltd.) having a thickness of 60 μm as a cycloolefin film, and dry and solidify with hot air in a 90 ° C. drying oven for 1 minute. Then, an easy-adhesion layer having a coating thickness of 0.4 μm was formed to obtain a film with an easy-adhesion layer.
Next, the above-mentioned hard coat layer paint is applied on the easy-adhesion layer of the film with the easy-adhesion layer using a bar coater and dried with hot air in a drying furnace at 80 ° C. for 1 minute to obtain a coating thickness of 5. A 0 μm coating layer was formed. This was cured using a UV irradiation apparatus set at a height of 60 mm from the coated surface at a UV irradiation amount of 150 mJ / cm ² to form a hard coat layer, and a hard coat film of this example was produced.

[Example 2]
A hard coat film was obtained in the same manner as in Example 1 except that the solid content ratio of the polyolefin resin and methyl methacrylate resin in the easy adhesion layer of Example 1 was 90/10.

[Example 3]
A hard coat film was obtained in the same manner as in Example 1 except that the solid content ratio of the polyolefin resin and methyl methacrylate resin in the easy-adhesion layer of Example 1 was 40/60.

[Example 4]
A hard coat film was obtained in the same manner as in Example 1 except that the coating thickness of the easy-adhesion layer in Example 1 was 0.1 μm.

[Example 5]
A hard coat film was obtained in the same manner as in Example 1 except that the thickness of the easy-adhesion layer in Example 1 was 1.0 μm.

[Example 6]
Instead of using the methyl methacrylate resin thermolac LP-45M30 used in the easy-adhesion layer of Example 1, “methyl methacrylate resin acrylate 0502TC (trade name)” (solid content 50%, manufactured by Taisei Fine Chemical Co., Ltd.) Obtained a hard coat film in the same manner as in Example 1.

[Example 7]
A hard coat film was obtained in the same manner as in Example 1 except that the cycloolefin film of Example 1 was changed to “ARTON FILM FEKP100 (trade name)” (manufactured by JSR Corporation) having a thickness of 100 μm.

[Example 8]
“UA-306H (trade name)” (solid content 100%, (meth) acryloyloxy group number: 3, in place of the urethane acrylate ultraviolet curable resin “purple light UV-7630B” used in the hard coat layer of Example 1 A hard coat film was obtained in the same manner as in Example 1 except that Kyoeisha Chemical Co., Ltd. was used.

[Example 9]
A hard coat film was obtained in the same manner as in Example 1 except that the solid content ratio of the polyolefin resin and methyl methacrylate resin in the easy adhesion layer of Example 1 was 37 parts / 63 parts.

[Example 10]
A hard coat film was obtained in the same manner as in Example 1 except that the solid content ratio of the polyolefin resin and methyl methacrylate resin in the easy-adhesion layer of Example 1 was 93 parts / 7 parts.

[Comparative Example 1]
Except that the solid content blending ratio of the polyolefin resin and methyl methacrylate resin of the easy-adhesion layer of Example 1 was 100 parts / 0 parts (that is, the polyolefin resin was used alone), it was the same as Example 1. To obtain a hard coat film.

[Comparative Example 2]
The same as Example 1 except that the solid content ratio of the polyolefin resin and methyl methacrylate resin in the easy-adhesion layer of Example 1 was 0 part / 100 parts (that is, the methyl methacrylate resin was used alone). Thus, a hard coat film was obtained.

The hard coat films of Examples and Comparative Examples produced as described above were evaluated for the following items, and the results are summarized in Table 1.
(1) Film thickness The formation thickness of the easy-adhesion layer and the hard coat layer was measured using Thin-Film Analyzer F20 (trade name) (manufactured by FILMETRICS).

(2) Transparency The total light transmittance was measured by the test method shown in JIS K7136 for the hard coat films prepared in each Example and Comparative Example.

(3) Adhesion (initial adhesion and adhesion over time)
The adhesion was evaluated according to JIS-K5600-5-6. In addition, in order to confirm the adhesion between the easy-adhesion layer and the cycloolefin film and the adhesion between the easy-adhesion layer and the hard coat layer, the easy-adhesion layer and the cycloolefin were formed by forming an easy-adhesion layer on the cycloolefin film. The adhesiveness to the film (indicated by “base material / easy-adhesive layer” in Table 1) is confirmed, and an easy-adhesion layer and a hard coat layer are formed on a cycloolefin film. Adhesion with the coating layer (indicated as “easily adhesive layer / hard coating layer” in the items in Table 1) was evaluated.
First, the adhesion (initial adhesion) between the easy-adhesion layer and the cycloolefin film is 1 mm using a cross-cut peel test jig under normal conditions, that is, constant temperature and humidity conditions (23 ° C., 53% RH). 100 cross-cuts of ² were prepared, Sekisui Chemical Co., Ltd. adhesive tape No. 252 was applied on it, pressed evenly with a spatula, then peeled in the direction of 90 degrees, leaving an easily adhesive layer The number was evaluated in four stages.
Next, the adhesion (initial adhesion) between the easy-adhesion layer and the hard coat layer was evaluated in the same manner. In addition, in the adhesion test of the hard coat layer where peeling occurred at the interface between the cycloolefin film and the easy adhesion layer, it was evaluated as “easy adhesion layer peeling”.
The evaluation criteria are as follows, and ◎ and ○ evaluation products were judged to have passed.
Evaluation criteria ◎: 100 pieces ○: 99 to 95 pieces △: 94 to 50 pieces ×: 49 to 0 pieces

  Furthermore, with respect to the adhesiveness over time, each hard coat film (with a hard coat layer coated on the easy-adhesive layer) prepared in the examples and comparative examples was sampled in a blow dryer at a temperature of 90 ° C. After storing for 30 days, a sample was taken out, and adhesion was evaluated according to JIS-K5600-5-6 described above. The evaluation criteria are the same as in the case of the above initial adhesiveness. For those with poor adhesiveness, the peeling interface was specified and listed in Table 1.

(4) Heat-resistant cracks Each hard coat film produced in Examples and Comparative Examples was suspended and stored for 5 minutes using a sample holder in a dryer at 100 ° C, and then the hard coat film sample was taken out and checked for cracks. Visual evaluation was made. The degree of occurrence of cracks was evaluated according to the following criteria. ○ The evaluation product was considered to have good heat-resistant cracks.
Evaluation criteria ○: No cracks occurred △: Some cracks occurred ×: Cracks occurred

(5) Scratch resistance About each hard coat film produced by the Example and the comparative example, the hard-coat layer surface was made into steel wool # 0000 by the test method according to JIS-K5600-5-10, and 1 kg of loads were applied. 10 times reciprocating friction was applied, and the degree of scratching was evaluated according to the following criteria. ○ Although the evaluation product has good scratch resistance, the evaluation product can also be used as a product.
Evaluation criteria ○: No scratches occurred. Δ: Some scratches occur. X: Innumerable scratches occur.

(6) Pencil hardness About the hard coat film produced by each Example and the comparative example, pencil hardness was measured by the test method according to JISK5600-5-4. The hardness without scratches on the surface was indicated.

  As is clear from the results of Table 1 above, according to the examples of the present invention, the cycloolefin film and the hard coat layer were formed by an easy-adhesion layer containing (in combination with) a mixture of polyolefin resin and methyl methacrylate resin. Adhesiveness with both can be improved, and a hard coat film having excellent adhesion over time under normal conditions and heat-and-moisture resistance conditions and free from cracks under heat-resistant conditions can be obtained. In addition, when an ionizing radiation curable resin contained in the hard coat layer has a resin having three or more (meth) acryloyloxy groups in one molecule, it has excellent surface hardness (abrasion resistance, pencil hardness). A coated film can be obtained.

  Moreover, the effect of this invention is more exhibited because the solid content mixture ratio (parts by weight) of the polyolefin resin and the methyl methacrylate resin in the easy-adhesion layer is in the range of 90/10 to 40/60. . Further, when the solid content blending ratio (parts by weight) of the polyolefin resin and the methyl methacrylate resin was 93 parts / 7 parts (Example 10) or 37 parts / 63 parts (Example 9), The quality was inferior due to the occurrence of any problems such as generation, deterioration of scratch resistance, and problems of poor adhesion with time.

  On the other hand, in Comparative Examples 1 and 2 in which any resin is used alone without using a polyurethane-based resin and a methyl methacrylate-based resin in combination in the easy-adhesion layer, the initial adhesion (with the easy-adhesion layer and the hard coat layer). Adhesiveness), adhesiveness over time under heat and humidity conditions is inferior, cracks are likely to occur under heat resistant conditions (Comparative Example 1), and initial adhesiveness (adhesion between easy-adhesion layer and cycloolefin film) Further, there was a problem (Comparative Example 2) that the adhesion with time was inferior under wet heat resistance.

1 Cycloolefin film 2 Easy adhesion layer 3 Hard coat layer 10 Hard coat film

Claims (5)

A hard coat film in which a hard coat layer is provided on at least one side of a cycloolefin film via an easy adhesion layer,
The easy-adhesion layer contains a mixture of a polyolefin resin and a methyl methacrylate resin, and the hard coat layer contains an ionizing radiation curable resin.   The hard coat film according to claim 1, wherein a blending ratio (parts by weight) of the polyolefin resin and the methyl methacrylate resin in the easy-adhesion layer is in a range of 90/10 to 40/60. .   The hard coat film according to claim 1 or 2, wherein the methyl methacrylate resin has a glass transition point of 90 degrees or more.   4. The hard coat film according to claim 1, wherein the ionizing radiation curable resin contains a polyfunctional acrylate having 3 or more (meth) acryloyloxy groups in one molecule. 5.   The hard coat film according to any one of claims 1 to 4, wherein the easy adhesion layer has a thickness in a range of 0.1 µm to 1.0 µm.

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