JP2005111769A - Manufacturing method of laminated film and surface protective film for liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a laminated film suitable as a surface protective film, excellent in blocking resistance, having no pollution problem due to dust in air and preventing the transfer of a pressure-sensitive adhesive to the surface of an adherend when the surface protective film is peeled after use, and the surface protective film for a liquid crystal display. <P>SOLUTION: In the manufacturing method of the laminated film wherein a pressure-sensitive adhesive layer is arranged between a peel layer and a base material layer, a polyamide resin, a polycarbonate resin, a polyester resin or a mixture of them is used in the peel layer and a polyolefin resin is used in the base material layer while a hydrogenated material of a random copolymer comprising styrene and a diene-based hydrocarbon, a mixture thereof or an ethylene/vinyl acetate copolymer mixture is used in the pressure-sensitive adhesive layer. The resins of the respective layers are together extruded into a cylindrical shape by a multilayered coextrusion circular die before cooled. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a laminated film and a surface protective film for a liquid crystal display, and more particularly relates to a method for producing a laminated film suitable as a surface protective film and a surface protective film for a liquid crystal display.

The surface protective film is used for protecting the surface of the liquid crystal display or the like by bonding it to various surfaces. Conventionally, as the layer structure of such a surface protective film, those of a base material layer / release layer and a release layer / base material layer / adhesive layer are known. As a resin for each layer, a polyolefin resin for the base layer, a thermoplastic resin for the release layer, a hydrogenated random copolymer composed of styrene and a diene hydrocarbon, a mixture thereof, or ethylene Vinyl acetate copolymer mixtures are known and are produced by coextruding each layer of resin into a cylinder with a multilayer coextrusion circular die and then air cooling.
JP-A-8-276485 JP-A-11-207882

  However, the surface protective film as described above has at least a drawback that it is easily blocked in the production process, and the adhesive is applied to the adherend surface when the surface protective film is peeled off from the adherend after use. There is also the disadvantage of transferring.

  The present invention has been made in view of the above circumstances, and the purpose thereof is a laminated film suitable as a surface protective film, which has excellent blocking resistance and is free from contamination problems due to dust in the air. An object of the present invention is to provide a method for producing a laminated film in which the transfer of the adhesive to the adherend surface is prevented when the surface protective film is peeled off later. Another object of the present invention is to provide a surface protective film for a liquid crystal display which is excellent in blocking resistance and does not have to worry about contamination due to dust in the air.

  As a result of various studies, the present inventor has obtained the following knowledge. That is, according to the laminated film in which the adhesive layer is disposed between the release layer and the base material layer, the blocking problem and the contamination problem due to dust in the air are eliminated, and the base material layer includes a polyolefin as a resin of each layer. Polyamide resin, polycarbonate resin, polyester resin or a mixture thereof for the resin and release layer, and a hydrogenated random copolymer composed of styrene and diene hydrocarbon, a mixture thereof, or an ethylene-vinyl acetate copolymer for the adhesive layer By adopting a specific manufacturing method using the mixture, the problem of transfer of the adhesive to the adherend surface is prevented.

  The present invention has been completed based on the above findings, and the first gist thereof is a method for producing a laminated film in which an adhesive layer is disposed between a release layer and a base material layer, the release layer being Is a polyamide resin, a polycarbonate resin, a polyester resin or a mixture thereof, a polyolefin resin is used for the base layer, and a hydrogen of a random copolymer composed of styrene and a diene hydrocarbon is used for the adhesive layer. An additive, a mixture thereof, or an ethylene-vinyl acetate copolymer mixture is used, and a resin in each layer is coextruded into a cylindrical shape by a multilayer coextrusion circular die, and then cooled, and then a method for producing a laminated film.

  And the 2nd summary of this invention is the surface protection film for liquid crystal displays which laminated | stacked the adhesion layer between the peeling layer and the base material layer, Comprising: The said peeling layer is a polyamide resin, polycarbonate resin, polyester resin, or The adhesive layer is composed of a random copolymer hydrogenated mixture of styrene and a diene hydrocarbon, a mixture thereof or an ethylene-vinyl acetate copolymer mixture, and the base layer is composed of a polyolefin resin. It exists in the surface protection film for liquid crystal displays characterized by being comprised.

  According to the present invention, the occurrence of blocking is prevented in the manufacturing process, the production can be efficiently performed, and the clean state can be maintained until just before use, so that contamination due to dust in the air can be prevented. The industrial value of the invention is remarkable. Moreover, when the surface protective film for liquid crystal displays is peeled off from the adherend after use, the adhesive does not tear or tear, and the adhesive is not transferred to the surface of the liquid crystal display.

  Hereinafter, the present invention will be described in detail. First, the manufacturing method of the laminated | multilayer film of this invention is demonstrated. The laminated film of the present invention comprises three functional layers as well as a conventionally known surface protective film, for example, a surface protective film comprising a release layer / base material layer / adhesive layer. The resin used for each layer is basically the same as a conventionally known surface protective film.

  The resin for forming the release layer may be any resin that is not thermally fused to the adhesive layer, for example, a polyamide resin such as 6 nylon or 6/66 nylon, a polycarbonate resin, a polyester resin such as polyethylene terephthalate, polybutylene terephthalate, or the like. The mixture can be used. A polyamide resin is particularly preferable.

  The resin constituting the base layer may be any resin that adheres to the adhesive layer, for example, a polyethylene resin such as a low density polyethylene resin, a medium density polyethylene resin, a high density polyethylene resin, a linear low density polyethylene resin, Polyolefin resin such as polypropylene resin can be used. In particular, a polypropylene resin is preferable.

  Examples of the resin forming the adhesive layer include a hydrogenated random copolymer composed of styrene and a diene hydrocarbon, a mixture of a random copolymer hydrogenated from a styrene and diene hydrocarbon added with a polypropylene resin, and A mixture of an ethylene-vinyl acetate copolymer to which a terpene phenol resin is added can be used. Examples of the hydrogenated product include a hydrogenated random copolymer composed of 1 to 50% by weight of styrene and 99 to 50% by weight of diene hydrocarbon such as isoprene and butadiene. In particular, a hydrogenated product of a styrene-butadiene random copolymer is preferable. The amount of the polypropylene resin in the mixture of the random copolymer hydrogenated product comprising styrene and diene hydrocarbon is usually 30% by weight or less. The amount of terpene phenol resin in the ethylene-vinyl acetate copolymer mixture is usually 5 to 30% by weight.

  It is important that the laminated film of the present invention has a layer structure (peeling layer / adhesive layer / base material layer) in which an adhesive layer is disposed between the release layer and the base material layer. By adopting such a layer structure, the problem of blocking and contamination due to dust in the air are eliminated.

  The production method of the laminated film according to the present invention is basically the same as the conventionally known multilayer coextrusion inflation method, a step of coextrusion into a cylindrical shape by a multilayer coextrusion circular die, and a step of cooling the cylindrical film including. In the present invention, after the cylindrical film is cooled, it is folded and pulled by a conventionally known method, the step of opening both ends, and a laminated film or outer layer comprising a release layer, an adhesive layer and a base material layer. You may perform the process of winding up the laminated | multilayer film which consists of an adhesion layer and a base material layer, peeling off the peeling layer.

  In a specific production method, a resin constituting each layer is introduced into a multilayer coextrusion circular die so as to have a layer structure in which an adhesive layer is disposed between the release layer and the base material layer, and coextruded into a cylindrical shape. Then, air is introduced into the co-extruded cylindrical molten film to be expanded, and then cooled and solidified.

  In the production method of the present invention, water or air, preferably water, is used as the cooling medium in the cooling and solidifying step. In particular, the pressure-sensitive adhesive layer of the laminated film obtained by the water cooling method is more flexible and more transparent than the pressure-sensitive adhesive layer of the laminated film obtained by the air cooling method.

  Cooling and solidification with water is performed, for example, by flowing water through a sizing ring installed around a cylindrical film.

  The thickness of the release layer of the laminated film obtained by the above method is usually 10 to 100 μm, preferably 20 to 50 μm, and the thickness of the adhesive layer is usually 5 to 50 μm, preferably 10 to 30 μm. The thickness is usually 10 to 100 μm, preferably 30 to 70 μm.

  If the thickness of the release layer is less than 10 μm, there is a risk of tearing at the time of release, and if it exceeds 100 μm, an economic problem occurs. When the thickness of the adhesive layer is less than 5 μm, it is difficult to obtain a uniform adhesive force due to uneven thickness of the adhesive layer. And when the thickness of a base material layer is less than 10 micrometers, there exists a possibility of breaking at the time of peeling of the surface protection film after use, and when it exceeds 100 micrometers, an economical problem arises.

  Next, the surface protective film for liquid crystal displays of the present invention will be described. The surface protective film for a liquid crystal display of the present invention is a surface protective film for a liquid crystal display in which an adhesive layer is laminated between a release layer and a base material layer, and the release layer comprises a polyamide resin, a polycarbonate resin, a polyester resin or The adhesive layer is composed of a random copolymer hydrogenated mixture of styrene and a diene hydrocarbon, a mixture thereof or an ethylene-vinyl acetate copolymer mixture, and the base layer is composed of a polyolefin resin. It is configured. And according to the preferable aspect of this invention, it manufactures by the method of coextruding the resin of each layer to a cylinder shape with a multilayer coextrusion circular die, and then cooling.

  The surface protective film for a liquid crystal display of the present invention is used to protect the surface of the liquid crystal display by being bonded to the surface. That is, in the layer structure of release layer / adhesion layer / base material layer, the release layer is peeled off and used, and the surface protective film (adhesion layer / base material layer) is peeled off from the surface of the liquid crystal display after use. At that time, the pressure-sensitive adhesive is not transferred to the surface of the liquid crystal display in the surface protective film for liquid crystal display of the present invention.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example, unless the summary is exceeded. The transferability of the pressure-sensitive adhesive, the extrusion moldability, the inner surface blocking property of the cylindrical film, and the blocking property during storage of the surface protective film were measured by the following methods.

  The transferability of the adhesive was measured by the following transfer test method. A surface protective film was attached to a light guide plate whose surface was not contaminated so that no air bubbles would enter it, placed in a high-temperature and high-humidifier at 60 ° C. and 95% RH, and left for 120 hours. When the temperature of the surface protective film reached room temperature, the surface protective film on the light guide plate was peeled off, and the presence or absence of transfer was visually confirmed using a backlight. The transferability of the pressure-sensitive adhesive was represented by the evaluation that ○: no transfer, Δ: slight transfer, x: transfer remarkably unusable.

  Extrudability was expressed by evaluating the molding state of the multilayer coextrusion circular die by visual observation, ○: stable, Δ: unstable, ×: unmoldable.

  The inner surface blocking property of the tubular film was expressed by evaluating the workability when the both ends of the film were cut open, ○: can be opened, △: wrinkled when opened, ×: not opened at all. .

Example 1:
6 nylon (trade name “1022ck7” manufactured by Mitsubishi Engineering Plastics Co., Ltd.) as a resin for forming an outer release layer, and a random copolymer of 10% by weight of styrene and 90% by weight of butadiene as a resin for forming an adhesive layer of an intermediate layer Hydrogenated product (manufactured by JSR, trade name “1320P”), random PP (manufactured by Nippon Polychem, trade name “EG7F”) is used as the resin for forming the inner base material layer, the outer layer thickness is 40 μm, and the intermediate layer A cylindrical extrusion is performed by a three-layer coextrusion inflation method so that the thickness of the inner layer becomes 10 μm and the thickness of the inner layer becomes 60 μm, and air is introduced into the obtained cylindrical molten film to be inflated, and then installed around the cylindrical molten film It is obtained after releasing water from the sizing ring, cooling and solidifying the cylindrical molten film, folding it with a pinch roll, taking it off, and cutting both ends. Film was wound.

Example 2:
In Example 1, as a resin for forming the adhesive layer, an ethylene-vinyl acetate copolymer (manufactured by Nippon Polychem, trade name “LV441” was used instead of a random copolymer hydrogenated product of 10% by weight of styrene and 90% by weight of butadiene. A film was prepared in the same manner as in Example 1 except that a mixture of 90% by weight and 10% by weight of terpene phenol resin (trade name “YS Polystar TH-130” manufactured by Yashara Chemical Co., Ltd.) was used.

Comparative Example 1:
In Example 1, a film was prepared in the same manner as in Example 1 except that the cylindrical molten film was extruded by a three-layer coextrusion inflation method so that the base layer was an intermediate layer and the adhesive layer was an inner layer. .

Comparative Example 2:
In Example 1, a film was prepared in the same manner as in Example 1 except that the cylindrical molten film was extruded by a three-layer coextrusion inflation method so that the adhesive layer was an outer layer and the release layer was an intermediate layer.

  Table 1 shows the results of the transferability of the pressure-sensitive adhesive, the extrusion moldability, the inner surface blocking property of the tubular film, and the blocking property during storage of the surface protective film obtained in the examples and comparative examples described above.

  As is clear from the above results, in the case of Examples, blocking of the inner surface of the film and blocking during storage of the film were not confirmed. And the transfer of the adhesive was not confirmed on the surface of the light guide plate after the high temperature and high humidity test. On the other hand, in the case of Comparative Example 1 in which the adhesive layer was arranged as the inner layer, the inner surface of the film was blocked, and the opening process could not be performed. And in the case of the comparative example 2 by which the adhesion layer was arrange | positioned as an outer layer, dust and other foreign materials have adhered to the adhesion layer, and when it winds up, a tarmi and a wrinkle generate | occur | produce, Furthermore, blocking occurs at the time of storage of a film. The film could not be opened.

Claims (2)

  A method for producing a laminated film in which an adhesive layer is disposed between a release layer and a substrate layer, wherein the release layer uses a polyamide resin, a polycarbonate resin, a polyester resin, or a mixture thereof, Uses a polyolefin resin, and the adhesive layer uses a hydrogenated random copolymer of styrene and diene hydrocarbon, a mixture thereof, or an ethylene-vinyl acetate copolymer mixture. A method for producing a laminated film, comprising coextruding into a cylindrical shape by an extrusion circular die and then cooling.   A surface protective film for a liquid crystal display in which an adhesive layer is laminated between a release layer and a base material layer, wherein the release layer is composed of a polyamide resin, a polycarbonate resin, a polyester resin, or a mixture thereof, A liquid crystal display comprising a random copolymer hydrogenated product comprising styrene and a diene hydrocarbon, a mixture thereof or an ethylene-vinyl acetate copolymer mixture, wherein the base layer is composed of a polyolefin resin. Surface protective film.