KR101133482B1 - Hard coat film and process for preparation thereof - Google Patents

Abstract

The present invention provides a hard coat film in which a hard coat layer is formed by using a triacetyl cellulose film as a support, which improves the suppression of curl and the humidity dependency of curl, and is excellent in transparency and surface hardness.

The hard coat film of this invention uses a triacetyl cellulose film as a support body, and the hard coat film which formed the hard-coat layer containing an ultraviolet curable resin or a radiation curable resin on it, The hard coat layer is a Japanese industry of the said support body. It is formed on the side of the surface energy measured according to the standard (JIS) K 6768 at least 35mN / m.

Triacetyl cellulose film, hard coat film, hard coat layer

Description

Hard coat film and its manufacturing method {HARD COAT FILM AND PROCESS FOR PREPARATION THEREOF}

The present invention relates to a hard coat film having a small film curl due to hardening shrinkage of the hard coat layer when the hard coat layer is formed on one side of the triacetyl cellulose film, and suppressing humidity dependency. The present invention relates to a hard coat film suitable for protecting the surface of an electronic information display such as a screen display of a mobile phone or a PC and having excellent handling properties.

In order to protect the surface, various display bodies or glass, such as a liquid crystal display, a CRT, a plasma display, an outdoor display panel, and an electronic display board, are used for the hard-coat film which used the thermoplastic resin film as a support body, and formed the hard coat layer on it. . In particular, a flat panel typified by a liquid crystal display has a triacetyl cellulose film being used as the thermoplastic resin film of the support because of its high light transmittance, few defects and no polarization.

In general, as a hard coat treatment method, a hard coat layer is formed by coating an ultraviolet curable resin or a radiation curable resin on the surface of a thermoplastic resin film. The ultraviolet curable resin or the radiation curable resin is composed of a monomer, an oligomer, and a photoinitiator, and the resin is hardened by three-dimensional crosslinking to express rigidity. Film curl arises by hardening shrinkage accompanying hardening of this resin. Although a triacetyl cellulose film is used universally from the said characteristic in a thermoplastic resin film, since the film is low in intensity | strength and film curls remarkably generate | occur | produce, handling property is bad and it causes a productivity fall. Since the demand for thinner and lighter displays becomes higher, the film used as a support becomes thinner and lower in rigidity, and thus the improvement of film curl has become a big problem.

Moreover, since the film hard-treated with the triacetyl cellulose film is used as a structural member of a polarizing plate, saponification process with alkali is given in order to acquire adhesiveness with a polarizing film. At this time, processes such as saponification treatment, washing, and drying are carried out in a high humidity environment, so that if there is a humidity dependency of the film curl, handling properties are deteriorated.

The following techniques are known to improve these film curls. For example, a radiation curable resin containing a polyfunctional urethane acrylate obtained by reacting a polyisocyanate with a radiation curable polyfunctional (meth) acrylate having at least two or more (meth) acryloyl groups and hydroxyl groups in a molecule thereof. A film having a cured coating layer of the composition (Japanese Patent Laid-Open No. 2001-113648) or a crosslinkable polymer containing both of a compound containing two or more ethylenically unsaturated groups in the same molecule, and a ring-opening polymerizable group and ethylene in the crosslinkable polymer Techniques for curing compositions cured by polymerizing both of the unsaturated unsaturated groups and hard coat treated products using the same are disclosed (Japanese Patent Laid-Open No. 2003-147017).

However, it has been found that the above known techniques have the following problems, respectively. Although the effect of the technique of Unexamined-Japanese-Patent No. 2001-113648 is confirmed with respect to a polyester film (thickness 188 micrometers) with a thick base material and high rigidity, a film curl can be suppressed small in the triacetyl cellulose film of low base rigidity. none. Further, the technique described in JP-A-2003-147017 discloses that when a hard coat treatment is performed on a triacetylcellulose film, since the film has a dependency on humidity, the suppression of film curl is not sufficient, and good handling properties cannot be obtained.

Therefore, the present invention is to provide a hard coat film that is excellent in transparency and surface hardness while suppressing film curl and humidity dependence of film curl when a hard coat layer is formed using a triacetylcellulose film as a support. It was set as.

MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, it is not enough to reduce the cure shrinkage of an ultraviolet-ray or radiation-curable resin, and it focuses on the structure of a triacetyl cellulose film, especially the distribution of a plasticizer, and a plasticizer by surface energy. The estimation of distribution of was examined. As a result, it was found that the problem was solved by forming the hard coat layer on the side of the surface of the triacetyl cellulose film as a support, the surface energy measured according to Japanese Industrial Standard (JIS) K 6768 of 35 mN / m or more. .                         

That is, 1st invention is a hard-coat film which formed the hard-coat layer containing an ultraviolet curable resin or a radiation-curable resin on the support body, The support body is a triacetyl cellulose film, The hard coat layer is a Japanese industry of the said support body. It is a hard coat film characterized by forming on the surface of the side whose surface energy measured according to specification (JIS) K6768 is 35 mN / m or more.

In 1st invention, 2nd invention uses the triacetyl cellulose film of thickness 30-90 micrometers as a support body, It is a hard coat film characterized by the above-mentioned.

In 1st invention, 3rd invention uses the triacetyl cellulose film of thickness 30-60 micrometers as a support body, It is a hard coat film characterized by the above-mentioned.

4th invention is a manufacturing method of the hard-coat film which forms the hard-coat layer containing an ultraviolet curable resin or a radiation-curable resin on a support body, The support body is a triacetyl cellulose film, The hard coat layer is a It is a manufacturing method of the hard coat film characterized by forming on the surface of the side whose surface energy measured according to Japanese Industrial Standard (JIS) K 6768 is 35 mN / m or more.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The triacetyl cellulose film dissolves and disperses triacetyl cellulose, a plasticizer, a UV absorber, and a lubricant in a solvent to prepare a transparent viscous dope, and then casts a thin film on a rotating metal plate to produce a film. Then, after drying by hot air and peeling from a metal plate, a transparent triacetyl cellulose film is obtained. In this drying process, in the process of volatilizing a solvent from the surface which contact | connects air, it was confirmed that the highly polar plasticizer has a tendency to be localized on the metal plate side in which the solvent remains higher.

In addition, in the drying process after casting, the triacetyl cellulose film tends to shrink as the solvent volatilizes, but the film surface in contact with the metal plate cannot be shrunk because the film surface is supported by the metal plate, so that the film is produced while maintaining the shrinkage stress. And dry. When used in a treatment or environment in which a film swells, the triacetyl cellulose film which maintains a shrinkage stress, the shrinkage stress which the film itself has open | released, the surface which contact | connects a metal plate, ie, the surface in which the plasticizer is distributed a lot The curl is generated inside. When such a film is used as a support and a hard coat layer is formed using a coating material containing a solvent or the like, curling occurs on the side in contact with the metal plate. Moreover, when a hard coat film is exposed in a humid environment, the shrinkage stress which the film itself had open | releases, and the curl generate | occur | produces similarly with the surface of the side which contact | connected the metal plate inside.

The plasticizer used at the time of manufacture of a triacetyl cellulose film includes triphenyl phosphate, biphenyl diphenyl phosphate, dimethyl ethyl phosphate, ethyl phthalyl ethyl glycolate, etc. These are high in polarity compared with triacetyl cellulose. On the other hand, there is a correlation between the distribution of the plasticizer and the surface energy of the triacetyl cellulose film, and the higher the amount of plasticizer having a higher polarity, the lower the surface energy. In other words, the plasticizer is further ubiquitous on the surface of the side with low surface energy, and the surface (band surface) which is in contact with the metal plate at the time of triacetyl cellulose film production is unevenly distributed, and the surface energy is low. The uneven size of a plasticizer changes also with the drying process of a film, the kind of solvent used at the time of dope preparation, and the kind of plasticizer. The surface with more plasticizer distribution than a fixed standard, ie, the surface of the side whose surface energy measured according to JISK6768 is 35 mN / m or less, is a surface which contact | connects a metal plate normally, and the plasticizer is extremely ubiquitous. Conventionally, forming a hard coat layer on the band surface side is good in adhesion between the hard coat layer and the triacetyl cellulose film. Therefore, it was common to form a hard coat layer on the band surface, that is, the surface on the lower side of the surface energy.

MEANS TO SOLVE THE PROBLEM The present inventors discovered that suppression of a film curl and humidity dependence of a film curl can be improved by forming a hard-coat layer in the surface on the side whose surface energy of a triacetyl cellulose film is 35 mN / m or more, and completed this invention. It came to the following. In particular, in the thin triacetyl cellulose film having a thickness of 30 to 60 µm, the film curls when the hard coat layer is formed on the side of the surface energy of 37 mN / m or more, more preferably 40 mN / m or more. It is possible to suppress it. Moreover, when the surface energy of both surfaces is 35 mN / m or more, you may form a hard-coat layer in either surface. In a normal triacetyl cellulose film, the upper limit of surface energy is 50 mN / m. And when a triacetyl cellulose film whose difference in surface energy of front and back is 2 mN / m or less is used, film curl can be suppressed remarkably.

The triacetylcellulose film is produced by casting on a rotating metal plate to form a film as described above, but it is common to use a metal band or drum as the metal plate. In order to improve the surface energy of the triacetyl cellulose film, it is effective to uniformize the plasticizer distribution in the film thickness direction, but since the plasticizer is more uniformly produced by the drum method, in the present invention, Preference is given to using triacetylcellulose films.

In the triacetyl cellulose film used as a support for the hard coat film of the present invention, the size of the film curl varies depending on the thickness of the film, but the effect of curl suppression is applied when the present invention is applied when the film thickness is 30 to 90 µm. Is recognized, and the effect of curl suppression on the thin film whose film thickness is 30-60 micrometers is especially remarkable.

As described above, the hard coat film of the present invention is a hard coat film having a triacetyl cellulose film as a support and a hard coat layer containing an ultraviolet curable resin or a radiation curable resin on the support. UV-curable resin or radiation-curable resin is used by mixing (dissolving or dispersing) with a solvent as needed. As the solvent to be used, for example, known organic solvents such as aromatics such as toluene, alcohols such as methanol, ethanol and isopropyl alcohol, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellol solve It can be used by mixing. It is preferable that the triacetyl cellulose film has low solvent resistance and uses a solvent containing toluene as a main component in order to prevent whitening. In order to improve performance, the antifoaming agent, the leveling agent, the antistatic agent, the antioxidant, the ultraviolet absorber, the light stabilizer, the polymerization inhibitor, and the like may be contained within a range that does not affect the effect of the present invention. Moreover, in order to provide anti-glare property to an application layer, organic or inorganic fine particles, such as resin beads, such as a silica particle, an acrylic resin, a silicon resin, and a urethane resin, can also be added in the range which does not affect the effect of this invention. .

The ultraviolet curable resin or radiation curable resin used in the present invention is not particularly limited as long as it is a transparent resin that is cured by irradiating an electron beam or ultraviolet ray, and the like, for example, a urethane acrylate resin, a polyester acrylate resin, and an epoxy acryl. It can select suitably from rate resin.

As a preferable thing, what consists of ultraviolet curable polyfunctional acrylate which has two or more (meth) acryloyl groups in a molecule | numerator is mentioned. Specific examples of the ultraviolet curable polyfunctional acrylate having two or more (meth) acryloyl groups in the molecule include neopentyl glycol di (meth) acrylate, 1,6-hexanedioldi (meth) acrylate, trimethyl All propane tri (meth) acrylate, ditrimethylol propane tetra (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexane (meth) acrylate Polyol polyacrylates, diacrylates of bisphenol A diglycidyl ether, diacrylates of neopentyl glycol diglycidyl ether, di (meth) acrylates of 1,6-hexanediol diglycidyl ether Polyester (meth) acrylate obtained by esterifying epoxy (meth) acrylate, polyhydric alcohol, polyhydric carboxylic acid, and / or its anhydride, and acrylic acid, such as these Agent, there may be mentioned polyhydric alcohols, polyvalent isocyanate and hydroxyl group-containing (meth) acrylate obtained by reacting a urethane (meth) acrylate, polysiloxane (meth) acrylate and the like.

The ultraviolet curable polyfunctional acrylate may be used alone or in combination of two or more thereof, and the content thereof is preferably 50 to 95% by weight based on the resin solid content of the paint for hard coat layer. In addition to the above polyfunctional (meth) acrylate, preferably 10 wt% or less of 2-hydroxy (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and glycy to the resin solid content of the coating material for the hard coat layer. Monofunctional acrylates, such as dill (meth) acrylate, can also be added.

Moreover, the polymeric oligomer used for the purpose of adjusting hardness can be added to a hard-coat layer. As such an oligomer, terminal (meth) acrylate polymethyl (meth) acrylate, terminal styryl poly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethylene glycol, terminal (meth) acrylate And macromonomers such as -acrylonitrile-styrene copolymer and terminal (meth) acrylate-styrene-methyl methacrylate copolymer, and the content thereof is preferably from 5 to about the resin solid content in the paint for hard coat. 50 wt%.

The hard coat layer of the present invention is formed by applying a coating composition on a transparent support using a known coating apparatus, and then irradiating and curing ionizing radiation. As a known coating apparatus, a coating apparatus such as a micro gravure coater, gravure coater, mayiba coater, die coater, or the like can be used. The viscosity and density | concentration of the coating composition at the time of application | coating can be adjusted to an appropriate value with the coating apparatus to be used. The film thickness of the hard coat layer after hardening is 1-20 micrometers normally, Preferably it is 2-10 micrometers. If the film thickness is less than 1 µm, the rigidity is lowered, and if it is thicker than 20 µm, the curl is large.

Example

Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to this. "Part" and "%" in an Example represent the "weight part" and the "weight%", respectively, unless there is particular notice.

The following items were evaluated about the hard coat film prepared in the Example and the comparative example.

1) surface energy

The surface energy of the support was measured according to JIS K 6768. In Table 4, the surface energy of the film used as a support body in an Example and a comparative example is shown.

2) transparency of coating layer

The haze degree of the hard coat film was measured based on JISK-7105 using the haze meter (made by Murakami Color Research Institute).

3) Adhesion

, 도포층 전체의 90% 미만이 박리된 것을

, 도포층 전체의 90% 이상이 박리된 것을 ×로 하였다.It evaluated by the board scale test based on JISK5400 (gap gap 1mm). The coating layer does not peel off at all from the base film

Less than 90% of the entire coating layer

The thing which 90% or more of the whole application layer peeled was made into x.

4) Pencil Hardness

It carried out based on JISK5400 using HEIDON14.

5) film curl

Chip-cut the hard coat film to A4 size (29.7 x 21.0 cm), and after 24 hours humidity control under normal environment (23 ° C, 50% RH), and high humidity (30 ° C, 90% RH), film curl The height was measured. The average value of the height of four corners was computed. Average height was 0 mm-15 mm: Very good, 15 mm-30 mm: Good, 30 mm-50 mm: Bad, and the cylindrical shape exceeding 50 mm: It was set as remarkably bad.

Example 1

A coating composition A shown in Table 1 below was coated with a bar coater on a surface having a triacetyl cellulose film (Fuji Photo Film Co., Ltd. type A) having a thickness of 80 μm as a support, and its surface energy of 37 mN / m. After evaporating the diluting solvent with a 80 degreeC dryer, UV light was irradiated and the hard coat film was obtained. The thickness of the hard coat layer at this time was 5 micrometers. About the obtained hard coat film, the transparency, adhesiveness, pencil hardness, and film curl of an application layer were evaluated, and the evaluation result was shown in Table 5.

Coating Composition A UV curable resin (trade name: UV-1700B, manufactured by Nippon Synthetic Chemical Co., Ltd.) 95.0 parts by weight Initiator (trade name: Irugacure 184, manufactured by Chiba Co., Ltd.) 5.0 parts by weight toluene 200.0 parts by weight Isopropyl Alcohol 50.0 parts by weight Fluorine-based surfactants (trade name: Megapak F-177, manufactured by Dainippon Ink Co., Ltd.) 0.05 parts by weight

[Example 2]

The same procedure as in Example 1 was carried out except that the coating composition A was applied to a surface having a triacetyl cellulose film (Fuji Photo Film Co., Ltd. type A) having a thickness of 80 µm as a support and its surface energy was 39 mN / m. The hard coat film was produced, and evaluation of the transparency, adhesiveness, pencil hardness, and film curl of the coating layer was made, and the evaluation results are shown in Table 5.                     

Example 3

It was the same as Example 1 except having used the triacetyl cellulose film (Fuji Photo Film Co., Ltd. type B) of 80 micrometers in thickness as a support body, and apply | coating coating composition A to the surface of this side whose surface energy is 41 mN / m. The hard coat film was produced, and evaluation of the transparency, adhesiveness, pencil hardness, and film curl of the coating layer was made, and the evaluation results are shown in Table 5.

Example 4

It was the same as Example 1 except having used the triacetyl cellulose film (Fuji Photo Film Co., Ltd. type B) of 80 micrometers in thickness as a support body, and apply | coating coating composition A to the surface of this side whose surface energy is 40 mN / m. The hard coat film was produced, and evaluation of the transparency, adhesiveness, pencil hardness, and film curl of the coating layer was made, and the evaluation results are shown in Table 5.

Example 5

It was hardly carried out similarly to Example 1 except having used the triacetyl cellulose film (Konica Co., Ltd. type C) of 80 micrometers in thickness as a support body, and apply | coating coating composition A to the surface whose surface energy is 37 mN / m. A coat film was produced and evaluated for transparency, adhesion, pencil hardness, and film curl of the coating layer, and the evaluation results are shown in Table 5.

[Example 6]

It was the same as Example 1 except having used the triacetyl cellulose film (Fuji Photo Film Co., Ltd. type D) of 40 micrometers in thickness as a support body, and apply | coating paint composition A to the surface whose surface energy is 40 mN / m. The hard coat film was produced, and evaluation of the transparency, adhesiveness, pencil hardness, and film curl of the coating layer was made, and the evaluation results are shown in Table 5.                     

Example 7

Except having apply | coated the coating composition B of Table 2, the hard coat film was produced like Example 1, the transparency, adhesiveness, pencil hardness, and film curl of the coating layer were evaluated, and the evaluation result was shown in Table 5.

Coating Composition B UV curable resin (trade name: UV-1700B, manufactured by Nippon Synthetic Chemical Co., Ltd.) 92.5 parts by weight Cyrisia 430 (manufactured by Fuji-Sirisia Co., Ltd.) 2.5 parts by weight Initiator (trade name: Irugacure 184, manufactured by Chiba Co., Ltd.) 5.0 parts by weight toluene 200.0 parts by weight Isopropyl Alcohol 50.0 parts by weight Siloxane-Based Surfactant (Brand Name: BYK-325, manufactured by Vicchemy) 0.05 parts by weight

Comparative Example 1

It was hardly carried out similarly to Example 1 except having used the triacetyl cellulose film (Konica Co., Ltd. type C) of 80 micrometers in thickness as a support body, and apply | coating paint composition A to the surface of the side whose surface energy is 34 mN / m. A coat film was produced and evaluated for transparency, adhesion, pencil hardness, and film curl of the coating layer, and the evaluation results are shown in Table 5.

Comparative Example 2

A polyester film having a thickness of 38 μm (trade name: A4300, manufactured by Toyo Spinning Co., Ltd.) was used as a support, and the same as that in Example 1 except that the coating composition A was applied to a surface having a surface energy of 48 mN / m. The hard coat film was produced, and evaluation of the transparency, adhesiveness, pencil hardness, and film curl of the coating layer was made, and the evaluation results are shown in Table 5.

Comparative Example 3                     

A coating composition C shown in Table 3 below using a triacetyl cellulose film (Konica Co., Ltd. type C) having a thickness of 80 µm as a support and a resin having a small curing shrinkage on the surface thereof having a surface energy of 34 mN / m. A hard coat film was produced in the same manner as in Example 1 except that the coating was carried out. The transparency, adhesion, pencil hardness, and film curl of the coating layer were evaluated, and the evaluation results are shown in Table 5.

Paint Composition C UV curable resin (trade name: UV-7640B, manufactured by Nippon Synthetic Chemical Co., Ltd.) 95.0 parts by weight Initiator (trade name: Irugacure 184, manufactured by Chiba Co., Ltd.) 5.0 parts by weight toluene 200.0 parts by weight Isopropyl Alcohol 50.0 parts by weight Fluorine-based surfactants (trade name: Megapak F-177, manufactured by Dainippon Ink, Inc.) 0.05 parts by weight

Support Surface energy (mN / m) Surface energy (mN / m) Metal plate type at the time of filmmaking Fuji Photo Film Co., Ltd. Type A 39 37 Metal band Fuji Photo Film Co., Ltd. Type B 41 40 drum Konica Corporation Type C 37 34 Metal band Fuji Photo Film Co., Ltd. Type D 40 39 Metal band A4300 (Two-Sided Adhesive Layer Treatment) 48 48 -

Haze degree (%) Adhesion Surface hardness Film curl Under normal circumstances In a humid environment Example 1 0.2 ○ 2H Very good Good Example 2 0.2 ○ 2H Very good Very good Example 3 0.2 ○ 2H Very good Very good Example 4 0.2 ○ 2H Very good Very good Example 5 0.1 ○ 2H Very good Very good Example 6 0.1 ○ 2H Very good Very good Example 7 5.3 ○ 2H Very good Very good Comparative Example 1 0.2 ○ 2H Bad Markedly bad Comparative Example 2 0.5 ○ 2H Good Good Comparative Example 3 0.2 ○ H Very good Markedly bad

As shown in Table 5, in the hard coat film of Examples 1-7 which formed the hard-coat layer on the surface of the triacetyl cellulose film which is a support body with the surface energy of 35 mN / m or more, film curl is remarkably suppressed and adhesiveness There was no problem in surface hardness. Example 7 mix | blended silica as a pigment and provided anti-glare property to the hard-coat film, but was also a problem also in adhesiveness and surface hardness similarly to Examples 1-6. On the other hand, the hard coat film of the comparative example 1 which provided the hard-coat layer in the surface of the side whose surface energy is less than 35 mN / m was not enough in suppressing film curl. In addition, in Comparative Example 3 in which the hard coat layer was formed on the surface having a surface energy of 34 mN / m and the resin had a small curing shrinkage, the surface hardness was lowered and the film curl suppression effect under general environment was confirmed. Inhibition of film curl under high humidity environment could not be obtained. Moreover, the hard coat film of the comparative example 2 which used the polyester film as a support body does not have the humidity dependence of the film curl as shown to a triacetyl cellulose film, and there was no problem also about adhesiveness and surface hardness.

 According to the present invention, it is possible to provide a hard coat film having a triacetyl cellulose film as a support and improving the suppression of film curl and the humidity dependency of the film curl when the hard coat layer is formed, and having excellent transparency and surface hardness. have.

Claims (4)

A hard coat film in which a hard coat layer containing an ultraviolet curable resin or a radiation curable resin is formed on a support, wherein the support is a triacetyl cellulose film, and the hard coat layer is subjected to Japanese Industrial Standard (JIS) K 6768 of the support. The hard coat film which is formed in the surface of the side which the surface energy measured according to is 35-50 mN / m. The hard coat film according to claim 1, wherein a triacetyl cellulose film having a thickness of 30 to 90 µm is used as the support. The hard coat film according to claim 1, wherein a triacetyl cellulose film having a thickness of 30 to 60 µm is used as the support. In the method for producing a hard coat film for forming a hard coat layer containing an ultraviolet curable resin or a radiation curable resin on a support, the support is a triacetyl cellulose film, and the hard coat layer is a Japanese Industrial Standard (JIS). A method for producing a hard coat film, characterized in that the surface energy measured in accordance with K 6768 is formed on the surface of the side of 35 to 50mN / m.