JP2006168238A - Protective film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a protective film in which a hard coat layer is laminated on a substrate film layer, and production efficiency is good when the hard coat layer is laminated and which is excellent in surface hardness. <P>SOLUTION: In the protective film in which the hard coat layer is laminated on at least one side of the substrate film layer, the hard coat layer is made of a cured membrane obtained by the addition polymerization of the uncured membrane of an acrylic monomer formed by a vacuum evaporation film forming method by irradiating the membrane with ultraviolet rays or electron beams. The acrylate monomer comprises at least one selected from the compounds obtained by replacing at least one acrylic group of pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylol propane triacrylate, and dimethylol tricyclodecane diacrylate with a methacrylic group. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a film used for protecting the surface of various life-related products and various electronic devices.

  Currently, plastics are lightweight and inexpensive in addition to excellent processability and transparency, and also have advantages in their optical properties, but on the other hand, they are softer than glass and are easily scratched. Have the disadvantages. Protective films used to protect the surfaces of various life-related products and various electronic devices are generally laminated with a hard coat layer to prevent scratches on the base film in order to improve these defects. Is used. A thermosetting coating agent such as a silicon coating agent, an acrylic coating agent, or a melamine coating agent is used for the hard coat layer, and a silicon coating agent is often used particularly in terms of hardness. However, the silicon-based coating agent is expensive, and further requires a long time for thermosetting, so a large-scale heat drying furnace is required for the production equipment, and the base film is easily deformed during the thermosetting. There was a negative effect.

  An object of the present invention is to provide a protective film in which a hard coat layer is laminated on a base film layer, which has good production efficiency when the hard coat layer is laminated and has an excellent surface hardness. There is.

  The invention according to claim 1 of the present invention is an acrylic monomer comprising a protective film in which a hard coat layer is laminated on at least one side of a base film layer, wherein the hard coat layer is formed by a vacuum deposition method. It is a protective film characterized by comprising a cured thin film obtained by irradiating an uncured thin film with ultraviolet rays or an electron beam for addition polymerization.

  The invention according to claim 2 of the present invention is the invention according to claim 1, wherein the acrylic monomer is an acrylic of pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, dimethyloltricyclodecanediacrylate. A protective film comprising at least one group in which at least one group is substituted with a methacryl group.

  The protective film of the present invention is a protective film in which a hard coat layer is laminated on at least one side of a base film layer, and an uncured thin film of an acrylic monomer formed by forming the hard coat layer by a vacuum deposition method It is composed of a cured thin film obtained by addition polymerization by irradiating UV or electron beam, and the acrylic monomer is pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, dimethyloltricyclodecanediacrylate Organic compounds that can be formed continuously and efficiently in the laminating process and volatilize to the atmosphere during laminating because they contain at least one acryl group substituted with at least one acrylic group Less hard coat layer And better surface hardness is also hard.

The protective film of this invention is demonstrated along embodiment. FIG. 1 is a side sectional view showing an embodiment of the protective film of the present invention. The protective film (10) has a structure in which a hard coat layer (12) is laminated on one side of a base film layer (11). .

  The film used for the base film layer (11) is polyolefin film, polyester film, polyamide film, polyimide film, acrylonitrile film, polyethersulfone film, polylactic acid film, polycarbonate film, vinyl chloride film, cellophane. A triacetyl cellulose film or the like can be used, and it is desirable to select appropriately according to the application and required physical properties. For example, when used for a furniture top plate, a polyethylene terephthalate film, a vinyl chloride film, a polyolefin film, a polyamide film, etc. are easy to use in terms of cost and are excellent in texture. An acrylic nitrile film having excellent weather resistance is suitable when used for coating signs and signs used outdoors. When used for applications in the field of electronic equipment, a triacetylcellulose film, a polyethersulfone film, a polyethylene terephthalate film, a polycarbonate film and the like are desirable. The thickness is 9 to 200 μm depending on the application.

  The hard coat layer (12) includes at least one obtained by substituting one or more acrylic groups of pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, or dimethyloltricyclodecane diacrylate with a methacrylic group. It is composed of a cured thin film obtained by addition polymerization by irradiating an uncured thin film of an acrylic monomer comprising an ultraviolet ray or an electron beam, and the formation method is performed on a base film layer in a vacuum deposition apparatus. An uncured thin film of the acrylic monomer is laminated, and the uncured thin film is irradiated with ultraviolet rays or an electron beam to undergo addition polymerization and cured to obtain a cured thin film.

  Generally, a hard coat layer made of an acrylic cured film is formed by applying a solution containing an acrylic monomer or oligomer by a die coating method or a lip coding method, and then applying various energies to cure it. However, this forming method is practically very slow at a processing speed of about 10 m / min, is not efficient, and the thickness of the cured film is about several μm. A thin film may be required. Since the hard coat layer (12) of the protective film (10) of the present invention is laminated by the above forming method, it can be made very thin, and the thickness is 0.05 to 20 μm. If it exceeds 20 μm, it is not good because it lacks flexibility and is easily broken.

  Usually, addition polymerization has a smaller volume change before and after polymerization, particularly shrinkage, compared to other polymerizations, and various adverse effects during coating and use are small. On the other hand, condensation polymerization has a low reaction rate and takes a long time to cure, and may contaminate other rolls in the web or migrate to the back surface of the base film layer. Is small. In addition polymerization, those having an acrylic group or a methacryl group are easy to handle, have excellent polymerizability, and the hardness of the thin film is often sufficient. In particular, it is preferable to use a methacrylic group to suppress skin irritation during the formation of a cured thin film or to obtain a hard film. Conversely, it is desirable to obtain a flexible film or polymerize efficiently with a low energy amount. When necessary, it can be appropriately adjusted by using an acrylic group. In practice, it is desirable to use a mixture of various monomers depending on handling properties and finally required physical properties.

Moreover, heat, an electron beam, or an ultraviolet ray is used as the energy applied for addition polymerization of the acrylic monomer. Among these, electron beams or ultraviolet rays are preferable. In this case, although there is polymerization heat generated, the polymerization reaction proceeds at a temperature much lower than that of a general heating method. For example, when an electron beam is used, many addition polymerization reactions proceed easily, but there are problems such as large charge on the base material and large addition to the base material. On the other hand, when ultraviolet rays are used Although a polymerization initiator is necessary and there is a concern that the polymerization initiator remaining after film formation may bleed, the problem of charging is largely eliminated. Accordingly, it is selected appropriately in consideration of the use and reactivity of the monomer used. The method of polymerizing by irradiating with an electron beam or ultraviolet rays allows the polymerization reaction to be performed at a low temperature, and reduces the rate of occurrence of chain transfer reaction, which is one of elementary reactions in radical polymerization, etc. Shift to higher. That is, the low molecular weight component decreases, which contributes to prevention of bleeding and also exhibits mechanical strength. Since the hard coat layer (12) of the protective film (10) of the present invention is formed by curing an acrylic monomer using an electron beam or ultraviolet rays in a vacuum vapor deposition apparatus, high-speed film formation is possible. In addition, the amount of volatile compounds in the atmosphere during lamination is small, and the environmental load is small. In addition, since it is formed under vacuum, there is very little contamination of foreign matters.

  Below, the protective film of this invention is demonstrated in more detail along a specific Example.

  A biaxially stretched polyester film (Toyobo Co., Ltd., trade name: A4300) having a thickness of 100 μm was used as the base film layer (11), and pentaerythritol triacrylate (Kyoeisha Chemical Co., Ltd.) was used in a vacuum film forming apparatus. , Trade name: light acrylate PE-3A) / neopentylglycol diacrylate (Kyoeisha Chemical Co., Ltd., trade name: light acrylate NP-A) = 90/10 (weight% ratio) mixture of monomer liquid under vacuum conditions After heating and evaporating under the condition, it was applied to one side of the biaxially stretched polyester film, and then irradiated with a 15 Mrad electron beam and cured to form a hard coat layer (12) consisting of a cured thin film having a thickness of 0.5 μm. The protective film of this invention was created.

  In Example 1, a monomer liquid composed of a mixture having the same mixing ratio was mixed with a blended liquid in which a benzophenone-based ultraviolet radical initiator was added to one side of a biaxially stretched polyester film, and then irradiated with 120 W / cm high-pressure mercury ultraviolet light. The protective film of the present invention was prepared in the same manner except that a hard coat layer (12) made of a cured thin film having a thickness of 0.5 μm was laminated.

  In Example 1, instead of pentaerythritol triacrylate, a protective film of the present invention was prepared in the same manner except that pentaerythritol tetraacrylate (Kyoeisha Chemical Co., Ltd., trade name: Light acrylate PE-4A) was used. .

  In Example 1, the protective film of this invention was similarly produced except having used trimethylol propane triacrylate (Kyoeisha Chemical Co., Ltd., light acrylate TMP-A) instead of pentaerythritol triacrylate.

  In Example 1, the protective film of the present invention was similarly used except that dimethylol tricyclodecane diacrylate (Kyoeisha Chemical Co., Ltd., trade name: Light acrylate DCP-A) was used instead of pentaerythritol triacrylate. It was created.

  In the following, comparative examples of the present invention will be described.

  A comparative protective film was prepared in the same manner as in Example 1 except that only neopentyl glycol diacrylate (Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate NP-A) was used as the monomer liquid.

<Evaluation>
Using the protective films of Examples 1 to 5 of the present invention and the protective film of Comparative Example 6, the pencil scratch value was measured by the following measurement method, and the hardness of the hard coat layer was evaluated. The results are shown in Table 1.
(1) Pencil Scratch Value Measuring Method The pencil scratch value on the hard coat layer surface of each protective film was measured by a measuring method based on the handwriting method of JIS K-5400, and the quality of the hardness was evaluated.

表１に示すように、本発明の実施例１〜５の保護フィルムのハードコート層はすべて良好な硬度を得た。一方、比較用の実施例６の保護フィルムのハードコート層はその硬度が劣っている。

As shown in Table 1, all the hard coat layers of the protective films of Examples 1 to 5 of the present invention obtained good hardness. On the other hand, the hardness of the hard coat layer of the protective film of Comparative Example 6 is inferior.

It is a sectional side view which shows one Embodiment of the protective film of this invention.

Explanation of symbols

10 ... Protective film 11 ... Base film layer 12 ... Hard coat layer

Claims (2)

  In a protective film in which a hard coat layer is laminated on at least one side of a base film layer, an ultraviolet or electron beam is irradiated onto an uncured thin film of an acrylic monomer formed by vacuum deposition. A protective film comprising a cured thin film obtained by addition polymerization.   The acrylic monomer comprises at least one obtained by substituting one or more acrylic groups of pentaerythritol triacrylate, pentaerythritol tetraacrylate, trimethylolpropane triacrylate, or dimethyloltricyclodecanediacrylate with a methacrylic group. The protective film according to claim 1.

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