JP3912861B2 - Method for producing field-selective film having craze - Google Patents

Description

上記の結果から明らかなように、本発明方法による実施例１及び２で得られた視野選択性フィルムは比較例１のものと比べ、入射角度が大きくなるにつれて透過率が低くなっており、良好な視野選択性を有していた。
【００６９】
実施例３
ポリスチレン樹脂（６６６Ｒ：旭化成工業社）をメチルエチルケトン、トルエンの混合溶媒に溶解し、ワイヤーバーにより厚さ５０μｍの透明ポリエステルフィルム上に塗布した後、加熱乾燥することにより、塗膜厚２０μｍのフィルムを得た。
【００７０】
得られたフィルムを、下記黒色着色液２を用いる以外は実施例１と同様の処理を行い、クレイズ部分が黒色に着色した視野選択性フィルムを得た。
【００７１】
黒色着色液２組成
・黒色染料（ＷＡＴＥＲ ＢＬＡＣＫ ２０重量部
４２Ｂ：中央合成化学社）
・水 ８０重量部
【００７２】
実施例４
実施例３で作成したポリスチレン樹脂塗工フィルムを上記黒色着色液２を用いる以外は実施例２と同様に処理し、クレイズ部分が黒色に着色された視野選択性フィルムを得た。
【００７３】
比較例２
実施例３で作成したポリスチレン樹脂塗工フィルムを上記黒色着色液２を用いる以外は比較例１と同様に処理し、クレイズ部分が薄く黒色に着色した視野選択性フィルムを得た。
【００７４】
実施例３，４及び比較例２の視野選択性フィルムを目視評価したところ、実施例３，４で作製したフィルムは透過性に明確な角度依存性が有り、斜めから見た場合の透過性が落ちるという視野選択性効果を示したが、比較例２で作製したフィルムは透過性の変化が少なく視野選択性効果が弱かった。
【００７５】
実施例５
次の組成の透明プラスチックフィルム用の塗工液を調製した。
・アクリディックＡ−８０７ ２０重量部
（５０％）（大日本インキ化学工業社）
・バーノック Ｄ−７５０ ２．８８重量部
（７５％）（大日本インキ化学工業社）
・メチルエチルケトン ６重量部
・トルオール ６重量部
【００７６】
この塗工液をワイヤーバーにより厚さ５０μｍの透明ポリエステルフィルム上に塗布した後、加熱乾燥することにより、塗膜厚２０μｍのフィルムを得た。これをさらに６０℃で４８時間キュアリングした。
【００７７】
得られたフィルムを実施例１と同様に処理し、クラック部分が黒色に着色した視野選択性フィルムを得た。
【００７８】
実施例６
実施例５で作成した樹脂塗工フィルムを実施例２と同様に処理し、クラック部分が黒色に着色した視野選択性フィルムを得た。
【００７９】
比較例３
実施例５で作成した樹脂塗工フィルムを比較例１と同様に処理し、クラック部分が極くわずかに着色した視野選択性フィルムを得た。
【００８０】
実施例５、６及び比較例３の視野選択性フィルムを目視評価したところ、実施例５、６で作製したサンプルは透過性に明確な角度依存性が有り、斜めから見た場合の透過性が落ちるという視野選択性効果を示したが、比較例３で作製したサンプルは透過性の変化が少なく視野選択性効果が弱かった。
【００８１】
実施例７
黒色着色液１の代わりに下記顔料分散液を用いる以外は、実施例１と同様にしてポリプロピレンフィルムのクレイズ部分に光散乱性物質が充填された視野選択性フィルムを得た。
【００８２】
顔料分散液組成
・酸化亜鉛（ＦＩＮＥＸ−２５： ２０重量部
堺化学工業社）
・アクリディックＡ−１６５ ９重量部
（４５％、大日本インキ化学工業社）
・メチルエチルケトン ２０重量部
・トルオール ２０重量部
【００８３】
実施例８
黒色着色液１の代わりに前記顔料分散液を用いる以外は実施例２と同様にしてポリプロピレンフィルムのクレイズ部分に光散乱性物質が充填された視野選択性フィルムを得た。
【００８４】
比較例４
黒色着色液１の代わりに前記顔料分散液を用いる以外は比較例１と同様にしてポリプロピレンフィルムのクレイズ部分に光散乱性物質が充填された視野選択性フィルムを得た。
【００８５】
実施例７，８及び比較例４の視野選択性フィルムを目視評価したところ、実施例７，８で作製したサンプルは透過性及び散乱性に明確な角度依存性が有り、斜めから見た場合の透過性が落ち、さらに散乱性を増すという視野選択性効果を示したが、比較例４で作製したサンプルは透過性及び散乱性の変化が少なく視野選択性効果が弱かった。
【００８６】
【発明の効果】
本発明の方法によれば、優れた視野選択性を有する、クレイズを利用した視野選択性フィルムを製造することができる。
【００８７】
また、本発明の方法によれば、クレイズは形成と同時に着色されるので形成されたクレイズを容易に認識でき、不良なクレイズ形成部分をクレイズ形成時に発見してその部分を除去したり、製造条件等を補正することができる。従って、クレイズを形成してから着色する場合に、着色されていないクレイズが判別しにくいためにクレイズ形成時に不良なクレイズ形成を発見できず、フィルム全体にクレイズを形成した後に着色して初めてクレイズ形成の不良が発見されるというような問題を回避することができる。
【００８８】
さらに本発明の方法によれば、クレイズの形成と着色を同時に行うので視野選択性フィルムの製造を一工程で行うことができ、製造工程を短縮することができるので、高い製造効率が得られる。
【図面の簡単な説明】
【図１】 本発明の方法により製造される視野選択性フィルムの機能を説明する図である。
【図２】 本発明の視野選択性フィルムの製造方法を説明する図である。
【図３】 本発明の視野選択性フィルムの製造方法を説明する図である。
【符号の説明】
１．．．視野選択性フィルム
２．．．クレイズ
３．．．物体
４．．．観察者
５．．．観察者
６．．．プラスチックフィルム
７．．．ブレード
８．．．小径のローラ
９．．．折り曲げ部
１０．．．着色液塗布装置
１１、１２．．．ローラ
１３．．．着色液
１４．．．着色液浴[0001]
[Industrial application fields]
The present invention relates to a method for producing a visual field selective film having a property of allowing light to pass in a specific range direction but not passing light in other directions, utilizing a regularly directional craze. In particular, the present invention relates to a method that can sufficiently fill a coloring substance in a craze and can produce a visual field selection film having excellent visual field selectivity.
[0002]
[Prior art]
Conventionally, as a film or sheet having visual field selectivity, a type that obtains visual field selectivity by scattering light in a specific direction and a film that obtains visual field selectivity by shielding light in a specific direction are known.
[0003]
In recent years, a visual field selective sheet using a large number of crazes regularly formed in a film has been developed, such as JP-A-6-82607, JP-A-7-146403, JP-A-7-241917, etc. Is disclosed.
[0004]
In these publications, a transparent polymer resin film having molecular orientation is bent using a blade or the like so that the molecular orientation direction is parallel to the blade of the blade, and in this state, tension is applied in the molecular orientation direction. In contrast, it is produced by taking up vertically in the vertical direction and generating stripes of crazes substantially parallel to the direction of molecular orientation. Light is scattered by the crazes themselves, or is blocked by a light-absorbing substance introduced into the crazes. Discloses a method for producing a visual field selective film that exhibits visual field selectivity.
[0005]
In the conventional field-selective film or sheet as described above, a film that uses only light scattering in the craze cannot completely block the light beam, and is not suitable for an application that dislikes glare.
[0006]
In JP-A-6-82607, a colorant can be introduced into the craze of the film formed as described above, and in JP-A-7-146403, a light-absorbing substance is introduced into the craze, thereby improving the light-shielding property of the craze. It also describes improvement, and when a light-absorbing substance, a light-scattering substance, or the like is filled in a craze or crack, a field-selective film with improved light-shielding properties and scattering properties than those not filled is obtained. It is done.
[0007]
However, in the prior arts including the above-mentioned publications, a light-absorbing substance is filled after forming crazes or cracks. In such a method, air already exists in a fine space in the crazes. For this reason, the entire space in the craze cannot be filled with a light-absorbing substance or the like.
[0008]
[Problems to be solved by the invention]
Therefore, the present invention has been completed to solve the above-mentioned problems, and in the production of a visual field selective film using craze, the craze is filled with a substance such as a light-absorbing substance in the craze. It is an object of the present invention to provide a method for producing a visual field selective film using craze, which can be sufficiently filled with the above-mentioned substances, and thus can further improve the visual field selectivity.
[0009]
[Means for Solving the Problems]
The present invention is a method for producing a field-selective sheet made of a transparent plastic film having a large number of regularly oriented crazes containing a coloring substance, wherein the directional crazes are formed on the plastic film, The present invention provides a method for producing a visual field selective film comprising introducing a coloring substance into a craze and forming the craze in the presence of a coloring liquid containing the coloring substance.
[0010]
In one aspect of the method of the present invention, a local fold is formed on the film by linearly applying a force to a plastic film to which tension is applied, and the film is pulled perpendicularly to the fold direction of the fold. A large number of crazes having a regular direction substantially parallel to the bending direction are formed on the film.
[0011]
In one specific example of the above aspect, the craze is generated in the presence of the coloring liquid by applying the coloring liquid to the surface of the film where the craze is formed before forming the local bent portion in the plastic film.
[0012]
In another specific example of the above-described embodiment, craze is generated in the presence of the coloring liquid by forming a local bent portion of the plastic film in the coloring liquid bath.
[0013]
In another aspect of the method of the present invention, the plastic film laminated on the other layer is peeled off so as to form a local fold, thereby forming a regular direction substantially parallel to the fold direction. A large number of crazes having the property are formed.
[0014]
In one specific example of the above embodiment, the craze is formed in the presence of the coloring liquid by disposing a locally bent portion of the film in the coloring liquid bath.
[0015]
In yet another embodiment of the method of the present invention, the film is treated with a solvent and / or surfactant prior to forming a local fold in the plastic film.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the manufacturing method of the visual field selectivity film of this invention is demonstrated in detail.
[0017]
The method of the present invention is a film that transmits light that is incident from a certain direction but cannot transmit light that is incident from another direction. Is a method for producing a film having a characteristic (visual field selectivity) that cannot be visually recognized from another direction. The visual field selectivity referred to in the present invention includes a property that light incident from a certain direction is transmitted but light having a specific wavelength incident from another direction cannot be transmitted. That is, when viewed from a certain direction, it is substantially colorless and transparent, but when viewed from another direction, it is transparent but colored in a specific color, and the object of that color behind the film is from that direction. Characteristics that cannot be visually recognized are also included in the visual field selectivity.
[0018]
The field-selective film produced by the method of the present invention is made of a transparent plastic having regular directional crazes containing coloring substances.
[0019]
The “craze” in the present invention refers to a substantially straight crack or crack formed on the surface of the plastic film. In general, resin fibrils that remain between the walls of cracks or cracks formed on a plastic film are referred to as "crazes", and those that are spread and have no resin fibrils remaining are referred to as "cracks". In some cases, the craze referred to in the present invention includes any of them.
[0020]
Further, “regular directionality” indicates that the above-mentioned crazes are formed in stripes substantially parallel to a certain direction, and each craze is also substantially parallel in the depth direction. The “transparent plastic film” referred to in the present invention means a plastic film having such a light transmittance that the film or the like that is behind it can be visually recognized by the naked eye. In addition, the film referred to in the present invention generally has a thickness of 10 μm to 2 mm, and includes both films and sheets in the normal sense.
[0021]
The function of the visual field selective film produced by the method of the present invention will be described with reference to the schematic diagram shown in FIG. The field-selective film 1 shown in cross section in FIG. 1 has a number of crazes 2 containing a light-absorbing substance therein. Therefore, the object 3 behind the visual field selection film 1 can be visually recognized from the direction of the observer 4, but cannot be visually recognized from the direction of the observer 5 by being crazed. Although the object etc. which are behind it can be visually recognized, it has the visual field selectivity that it cannot visually recognize from another direction.
[0022]
Also, Craze 2 may not completely block visible light, but may block only light of a specific wavelength. Such a craze is transparent but colored in a specific color. According to a film having such a craze, an object or the like behind it can be visually recognized from a certain direction. The field of view selectivity that the object of the same color as Craze cannot be visually recognized from the direction is obtained.
[0023]
The transparent plastic film used for the field-of-view selective film of the present invention is not particularly limited as long as it can form a regular directional craze by a method as described later. An amorphous thermoplastic resin, a thermosetting resin, an ultraviolet curable resin, or the like can be used.
[0024]
The transparent plastic film is not limited to a single layer made of one kind of resin, and may be a multilayer plastic film made of one or more kinds of resins. In the case of a multilayer plastic film, crazes can be formed in at least one of the layers.
[0025]
When a single-layer plastic film is used, it is appropriate that the film itself has a certain degree of flexibility (or high toughness). Otherwise, the film is easy to break and difficult to use practically. On the other hand, in the case of using a multilayer plastic film, in addition to the above-mentioned one that can be used for practical purposes by causing crazing with a single layer, if the crazing occurs because of its rigidity and brittleness, it breaks by itself. Even if it has physical properties that would cause a problem, it can be used practically by being laminated on a tough base film. Specifically, for example, a material exhibiting a flexural modulus of 3000 MPa or more can be said to have high rigidity and brittleness, and such a material is preferably used by being laminated on a base film. Conversely, a material having a flexural modulus lower than the above, preferably a flexural modulus of 2800 MPa or less, can be suitably used as a single layer film. However, in order to form crazes on a film by a method as described later, the flexural modulus is preferably 300 MPa or more.
[0026]
Examples of the resin capable of causing regular crazing as described above include polyvinylidene fluoride, polypropylene, polyamide, cellulose and the like as the thermoplastic crystalline resin, polystyrene as the thermoplastic amorphous resin, and the like. Examples include styrene resins such as styrene acrylonitrile, acrylonitrile butadiene styrene, styrene butadiene, polymethyl methacrylate, polyvinyl chloride, polyvinyl acetate, polycarbonate, etc. Thermosetting resins include epoxy resins, acrylic / epoxy resins, polyols Isocyanate urethane resins, phenol resins, melamine resins, etc., and UV curable resins include acrylic acrylate, polyester acrylate, urethane acrylate, epoxy acrylate. .
[0027]
If a thermosetting resin or ultraviolet curable resin is used, the physical properties of the resin can be changed by appropriately selecting the type of the main agent and the curing agent, or the reactive monomer or oligomer, so that an appropriate craze can be obtained. The physical properties of the resin can be easily obtained. Further, since the thermosetting resin and the ultraviolet curable resin are excellent in heat resistance, weather resistance, and the like, they are also excellent in stability for preserving the crazed state after the formation of the craze.
[0028]
Base films for laminating films of rigid and brittle materials as described above include polyethylene terephthalate, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyethylene naphthalate, polyethylene, ethylene vinyl acetate copolymer, ethylene vinyl. Examples thereof include at least one kind of alcohol copolymer, polypropylene, polyurethane, styrene butadiene copolymer and the like.
[0029]
A plastic film that generates crazing may or may not craze depending on the temperature of the material in the process of generating crazing (generally the atmospheric temperature of the process), and crazing may occur depending on the type of resin, molecular weight, etc. The temperature to do can be different.
[0030]
For example, when a resin material that causes craze at room temperature is selected, it can be manufactured at room temperature, which is extremely advantageous from the viewpoint of productivity. However, since the visual field selective film obtained by using such a resin causes a new craze by bending, it is laminated on a base material having an appropriate hardness so that it does not bend after the craze is formed. Or you have to put it on where you need it.
[0031]
Conversely, when a resin material that produces crazes only at a low temperature such as 0 ° C. or lower is selected, it is disadvantageous in terms of productivity because a low-temperature environment is required when producing crazes. However, a field-selectivity film manufactured from such a material does not generate new crazes even when it is bent at room temperature, so that stable field-selectivity can be obtained.
[0032]
As the plastic film used in the method of the present invention, considering the above points, a material suitable for the purpose and application can be selected based on the flexural modulus and the like.
[0033]
Two or more kinds of the above-mentioned resins for forming crazes may be mixed in order to adjust the width, interval, angle, length, and depth of the crazes, and the surface thereof may be matted. Organic or inorganic dyes, pigments and the like may be added. Additives such as an antistatic agent and an adhesion improver can be optionally contained.
[0034]
The method of producing a transparent plastic film that causes these regular crazing is not particularly limited, and generally a melt T-die extrusion method, an inflation method, a calendar method ( Rolling method), hot pressing method, etc., and multilayer products are generally prepared by melt coextrusion method, laminating method, coating method and the like.
[0035]
These plastic films may be molecularly oriented or may be substantially not molecularly oriented. Use of a molecularly oriented film is preferred because crazes are easily formed in the molecular orientation direction. When such molecular orientation is obtained by uniaxial stretching, although it depends on the resin used, generally a stretching ratio of about 1.2 to 6.0 times is preferable. If it is less than 1.2 times, the effect of orientation cannot be obtained, and if it is 6.0 times or more, it tends to tear in the orientation direction.
[0036]
Next, a method for causing craze in the transparent film as described above will be described. The method for producing crazing in a transparent film is not particularly limited as long as it can form crazing that imparts the above-mentioned field of view selectivity. Generally, a film or a roll having a small diameter is applied by applying tension to the film. To form a local fold in the film, and by pulling the film perpendicular to the fold direction, the fold is continuously formed in the entire film, and a large number of the film is substantially parallel to the fold direction. A method of forming a craze, a part of a layer including a film that generates crazing of a multi-layered film is peeled, and a local bent portion similar to the above method is formed by bending at the time of peeling. The method etc. which produce can be used.
[0037]
In the above method, when the film is bent, a stress is applied to the back (convex) side surface of the folded portion of the film in a direction perpendicular to the folding direction, and thereby the surface is substantially parallel to the folding direction. Crazes are formed as cracks in the film, and when the film is taken or peeled, bent portions are continuously formed in a certain direction over the entire film surface, and a large number of crazes with regular orientation are formed on the entire film. It is.
[0038]
The film having a craze obtained as described above can provide a certain visual field selectivity by incident light scattering at a regularly formed craze portion even under an appropriate condition, but as described above. In order to obtain high-performance visual field selectivity, it is preferable to contain a coloring substance functioning as a light-absorbing substance, a light-scattering substance or the like in the space of the craze.
[0039]
In a conventionally known method, a regular craze was previously formed on the above-mentioned film, and then the film was immersed in a solution or dispersion of a dye, pigment or the like, and the dye or the like was filled in the craze. However, in this method, it was not possible to sufficiently fill the craze with a dye or the like, and thus sufficient field selectivity could not be obtained.
[0040]
For example, when a craze having a width of about 0.1 μm to several μm is formed on a film in advance, air exists in the space, and a solution such as a dye or a dispersion is later applied to the film. Alternatively, even if the film is immersed in them, the solution or dispersion cannot be completely replaced with the air in the craze. Furthermore, in the case of a typical craze, there are many fibrils (molecular bundles) and voids (voids) in the space, and it has a fine sponge-like structure, which intrudes the solution and dispersion liquid. It also depends on obstruction.
[0041]
On the other hand, according to the method of the present invention, crazes are formed in the presence of a colored liquid that is a solution or dispersion containing a coloring substance. The entire volume of the craze is replaced and filled with the coloring liquid without leaving a space such as. This makes it possible to introduce a larger amount of coloring material into the film after forming the craze in the air and then introducing a solution such as the above dye into the film. Can be formed, and the visual field selectivity of the obtained visual field selective film is more excellent. Also, since the colored liquid fills the space of the craze simultaneously with the formation of the craze, the colored liquid does not enter as described above and the colored liquid contacts the entire surface of the craze wall, and the craze wall surface is not oxidized or contaminated by foreign substances. Adhesiveness to the craze wall surface is improved, and as a result, dyeing property is improved. In the present invention, “in the presence of a coloring liquid” means that there is sufficient coloring liquid to satisfy the entire capacity of the craze formed on the plastic surface on which the craze is formed during craze formation.
[0042]
In order to form a craze in the presence of a coloring liquid, when forming a craze by forming a local fold in the film and pulling the film perpendicular to the folding direction, for example, a schematic diagram is shown in FIG. As shown, a craze formation site formed by pressing a blade 7 (FIG. 2 (a)) or a small-diameter roller 8 (FIG. 2 (b)) against a plastic film 6 taken from a roller 11 to a roller 12 is bent. Before the film reaches the portion 9, the surface of the film is uniformly formed by using a coloring liquid coating apparatus 10 or a brush or the like which is composed of a hollow body provided with slits and the colored liquid 13 supplied into the hollow body is ejected from the slits. A coloring liquid is applied to the film 6 and the film is passed through the bent portion 9 in this state, or the film 6 has a blade 7 (FIG. 3A) as shown in FIG. It may be used or a method of placing a small diameter roller 8 (FIG. 3 (b)) of craze formation portion formed by pressing the bent portion 9 in the coloring baths 14.
[0043]
The blade or the small-diameter roller as described above is preferably made of a material that is not affected by the immersion color liquid, such as a metal or a fluororesin, and particularly in the case of a blade, it is precise from the viewpoint of friction with a film that causes craze. Those subjected to polishing are preferred.
[0044]
In addition, when a part of the multilayered film is peeled to form a craze by forming a local bent part on the film that generates craze, the bent part formed at the time of peeling is colored. This can be done by placing it in a liquid bath.
[0045]
Also, the resin solvent When treated with a surfactant or the like, the internal stress increases and a craze can be formed more easily (see JP-A-9-166702). Plastic film solvent , Treatment with surfactants, etc. solvent It can be carried out by immersing in a surfactant and a solution thereof. Used for such processing solvent Examples thereof include alcohols such as methyl alcohol, ethyl alcohol and isopropyl alcohol, hydrocarbons such as hexane and heptane, ketones such as acetone and methyl ethyl ketone, and mixtures thereof. Examples of the surfactant include polyoxyethylene alkyl ether, Examples include polyoxyethylene phenyl ether, alkylbenzene sulfonate, dialkyl sulfosuccinate and the like. When processing with such a solvent etc., a coloring substance can exist in these solvents etc., and crazes can also be formed in the solvent etc.
[0046]
After generating crazing and introducing a colored substance as described above, unnecessary liquid on the surface is removed by wiping with a roller or cloth, and unnecessary solvent is removed by drying, evaporation, etc. Can be obtained.
[0047]
In the present invention, the color of the coloring substance used as the light-absorbing substance is not particularly limited, and the types of dyes and pigments are not particularly limited. Preferable materials include pigments such as carbon black, aniline black, iron black, molybdenum red, and blue blue, and various dyes.
[0048]
Further, even when a light scattering material is used as the coloring material filled in the craze, good visual field selectivity can be obtained. Examples of such substances include pigments such as zinc oxide, titanium dioxide, calcium carbonate, and silica, and metal powders such as aluminum powder.
[0049]
These substances are usually used by dissolving or dispersing them in water or an organic solvent, but they may be used after further adding a resin.
[0050]
View selectivity by Craze, that is, the front transmittance of light (transmittance in the direction perpendicular to the film surface of Craze), the viewing angle (visible angle), etc. are the width, depth, distance between crazes formed, It may vary depending on the type, amount, etc. of the colored substance introduced into the craze. For example, the greater the width of the craze (the distance between the upper edges of the craze walls on the film surface when a colored substance is introduced and the plastic film is held flat), the more the distance between crazes (the distance between adjacent crazes) The smaller the is, the lower the front transmittance, and the narrower the interval between crazes, and the greater the craze depth, the narrower the viewing angle.
[0051]
In order to adjust the depth, angle, spacing (craze density), and the amount of colored substance introduced, etc., so as to obtain the desired field of view selectivity, the resin type, thickness, folding angle, folding, etc. of the film The curvature, film tension, take-up speed, process temperature, etc. can be adjusted appropriately. For example, the higher the rigidity of the selected resin, the smaller the width and interval of the craze and the greater the density. The greater the film folding angle, the higher the craze density and the greater the craze depth. In order to obtain a general field-selectivity film, the desired field-selectivity can be obtained by adjusting the folding angle, the film tension and the take-off speed if the resin type and thickness of the film are selected. it can. Although these conditions vary depending on the type of resin, etc., generally the folding angle is 30 to 150 ° (the film plane after the folding part is on the opposite side of the film plane before the folding part from the roller or blade). Angle, θ in FIGS. 2 and 3),
The tension can be adjusted within the range of a tension of 0.5 to 10 kgf / mm 2 and a take-up speed of 10 mm / min to 10 m / min.
[0052]
In addition, as described above, a craze that does not completely block visible light but blocks only light of a specific wavelength, the type of the colored substance as described above, the concentration of the solution or dispersion (colored liquid), It can be obtained by appropriately selecting and / or adjusting the size of the craze and the like as described above.
[0053]
The width of the craze obtained as described above is usually about 0.1 to 10 μm, and by using such a width, it is possible to obtain a light-shielding craze without greatly affecting the front transmittance. If the depth of the craze is about 1 μm, the visual field selectivity can be obtained, and the larger the viewing angle, the smaller the viewing angle. However, the upper limit may be the depth to reach the film on which the craze is formed. Crazes deeper than about 1 μm among the crazes formed as described above contribute to visual field selectivity. The length of the craze does not particularly affect the visual field selectivity and is not limited, but is usually several μm to several tens of mm.
[0054]
The visual field selective film thus obtained can be applied with a protective layer or laminated with a protective film for surface protection or the like.
[0055]
【Example】
EXAMPLES Hereinafter, although this invention is further demonstrated based on the following examples, this invention is not limited to these Examples.
[0056]
[I] Craze formation method
As shown in FIG. 2 (a) or 3 (a), a blade is applied to the film drawn between the rollers so that a local fold is formed at a fixed fold angle, and the film is formed at a predetermined tension and speed. The crazing is continuously generated in the blade portion by pulling off. In the following examples, the folding angle (the angle formed by the film plane after the folded portion on the side opposite to the blade with respect to the film plane before the folded portion, θ in FIGS. 2 (a) and 3 (a)) is 60. The tension was 0.68 kgf / mm2, and the take-up speed was 30 mm / min.
[0057]
[II] Coloring method
The present invention was carried out by the following three methods: a) and b) according to the present invention, and c) as a prior art method.
[0058]
a) Method of applying colored liquid to sample before craze formation
As shown in FIG. 2 (a), a colored liquid is uniformly applied using a brush to the surface of the film where the craze is formed before passing through the blade of the film to be taken. The craze formation and the crazing portion are colored simultaneously. Then, the excess colored liquid on the surface layer is wiped off.
[0059]
b) Method of forming crazes in a colored liquid
As shown in FIG. 3 (a), a container filled with the coloring liquid is set in the craze forming apparatus so that the blade tip enters the coloring liquid, and the film is taken out in this state. As a result, the film passes through the coloring liquid at the blade portion, and the formation of the craze and the coloring in the craze can be performed simultaneously. Then, the excess coloring liquid on the surface layer and the back surface is wiped off.
[0060]
c) Method of coloring after forming crazes
After forming the craze, a colored liquid is applied to the crazed portion with a brush and left for a predetermined time, and then the excess colored liquid on the surface layer is wiped off.
[0061]
[III] Evaluation method
A light source and a light receiving portion are installed so that the laser light emitted from the laser light source strikes the light receiving portion of an optical power meter (Optical Power Meter TQ8210: Advantest), and a sample of a visual field selective film is colored in this laser light path. Set up a sample installation place so that the part comes. By changing the installation angle of the sample, the incident angle, that is, the angle formed by the optical path with respect to the direction perpendicular to the film surface of the field-selective film sample is changed every 10 degrees from -60 degrees to 60 degrees. Then, change the incident angle of the laser beam to the sample, and obtain the transmittance at each incident angle from the value of the power meter at each angle. The incident angle is changed with the craze length direction of the sample as an axis. The transmittance at each angle is calculated by the following equation.
[0062]
Transmittance = Measured value when the sample is installed at each angle / Measured value when there is no sample × 100 (%)
[0063]
Example 1
A uniaxially stretched polypropylene film having a thickness of 25 μm and a stretching ratio of about 3 times was cut into 5 cm wide strips so that the stretching direction was the width direction, and this was formed into a craze by the above-described craze forming method a) and colored. . The following black colored liquid 1 was used as the colored liquid. Thereafter, the excess black colored liquid on the surface layer was wiped off with a cloth impregnated with meta-modified alcohol to obtain a film in which only the craze portion was colored black.
[0064]
Black colored liquid 1 composition
・ Black dye (VALIFAST 10 parts by weight
BLACK 3810: Orient Chemical Industry Co., Ltd.)
・ Methyl ethyl ketone 45 parts by weight
・ 45 parts by weight of toluol
[0065]
Example 2
Using the same uniaxially stretched polypropylene film sample as in Example 1, crazes were formed and colored by the above-mentioned craze formation method b). The black colored liquid 1 was used as the colored liquid. Thereafter, excess colored liquid on the film surface layer and the back surface was wiped off with a cloth soaked with meta-modified alcohol to obtain a film in which only the craze portion was colored black.
[0066]
Comparative Example 1
Using the same uniaxially stretched polypropylene film sample as in Example 1, crazes were formed by the above-described craze formation method c), and then colored. The black colored liquid 1 was used as the colored liquid. Thereafter, the excess colored liquid on the surface layer of the film was wiped off with a cloth soaked with meta-modified alcohol to obtain a film in which only the craze portion was colored black.
[0067]
About the film produced in Examples 1, 2 and Comparative Example 1, the measurement result of the laser beam transmittance in each incident angle is described in the following table. The measurement followed the method described above.
[0068]
[Table 1]

As is clear from the above results, the visual field selective film obtained in Examples 1 and 2 according to the method of the present invention has a lower transmittance as the incident angle becomes larger than that of Comparative Example 1, and is good. It had excellent visual field selectivity.
[0069]
Example 3
A polystyrene resin (666R: Asahi Kasei Kogyo Co., Ltd.) is dissolved in a mixed solvent of methyl ethyl ketone and toluene, applied onto a transparent polyester film having a thickness of 50 μm with a wire bar, and then dried by heating to obtain a film having a coating thickness of 20 μm. It was.
[0070]
The obtained film was treated in the same manner as in Example 1 except that the following black colored liquid 2 was used to obtain a visual field selective film in which the craze portion was colored black.
[0071]
Black colored liquid 2 composition
・ Black dye (WATER BLACK 20 parts by weight)
42B: Chuo Synthetic Chemical Co., Ltd.)
・ 80 parts by weight of water
[0072]
Example 4
The polystyrene resin-coated film prepared in Example 3 was treated in the same manner as in Example 2 except that the black colored liquid 2 was used to obtain a visual field selective film in which the craze portion was colored black.
[0073]
Comparative Example 2
The polystyrene resin-coated film prepared in Example 3 was treated in the same manner as in Comparative Example 1 except that the black colored liquid 2 was used to obtain a visual field selective film in which the craze portion was lightly colored black.
[0074]
Examples 3 and 4 and Comparative Example 2 Field of view selectivity film As a result of visual evaluation, the films produced in Examples 3 and 4 had a clear angle dependency in permeability, and showed a visual field selectivity effect in which the transparency when viewed from an oblique direction was lowered. Comparative Example 2 The film produced in step 1 had little change in permeability and weak visual field selectivity effect.
[0075]
Example 5
A coating solution for a transparent plastic film having the following composition was prepared.
・ Acridick A-807 20 parts by weight
(50%) (Dainippon Ink Chemical Co., Ltd.)
・ Bernock D-750 2.88 parts by weight
(75%) (Dainippon Ink Chemical Co., Ltd.)
・ Methyl ethyl ketone 6 parts by weight
・ Toluol 6 parts by weight
[0076]
This coating solution was applied on a transparent polyester film having a thickness of 50 μm with a wire bar, and then dried by heating to obtain a film having a coating thickness of 20 μm. This was further cured at 60 ° C. for 48 hours.
[0077]
The obtained film was processed in the same manner as in Example 1 to obtain a visual field selective film in which the crack portion was colored black.
[0078]
Example 6
The resin coated film prepared in Example 5 was processed in the same manner as in Example 2 to obtain a visual field selective film in which the crack portion was colored black.
[0079]
Comparative Example 3
The resin-coated film prepared in Example 5 was processed in the same manner as in Comparative Example 1 to obtain a visual field selective film in which crack portions were very slightly colored.
[0080]
When the visual field selectivity films of Examples 5 and 6 and Comparative Example 3 were visually evaluated, the samples produced in Examples 5 and 6 had a clear angle dependency in the transparency, and the transparency when viewed from an oblique direction was observed. Although the visual field selectivity effect of falling was shown, the sample produced in Comparative Example 3 had little change in permeability and weak visual field selectivity effect.
[0081]
Example 7
A field-selective film was obtained in the same manner as in Example 1 except that the following pigment dispersion was used instead of the black colored liquid 1 and the light scattering material was filled in the crazed portion of the polypropylene film.
[0082]
Pigment dispersion composition
・ Zinc oxide (FINEX-25: 20 parts by weight
Sakai Chemical Industry)
・ Acridic A-165 9 parts by weight
(45%, Dainippon Ink & Chemicals, Inc.)
・ Methyl ethyl ketone 20 parts by weight
・ Toluol 20 parts by weight
[0083]
Example 8
A visual field selective film was obtained in which the light scattering material was filled in the crazed portion of the polypropylene film in the same manner as in Example 2 except that the pigment dispersion was used instead of the black colored liquid 1.
[0084]
Comparative Example 4
A field-selective film in which a light scattering material was filled in a crazed portion of a polypropylene film was obtained in the same manner as in Comparative Example 1 except that the pigment dispersion was used instead of the black colored liquid 1.
[0085]
Examples 7 and 8 and Comparative Example 4 Field of view selectivity film As a result of visual evaluation, the samples produced in Examples 7 and 8 have a clear angle dependency in the transparency and the scattering property, the transparency when viewed from an oblique direction is lowered, and the viewing selectivity is further increased. Showed effect, but comparative example 4 The sample produced in (1) had little change in transmission and scattering, and the visual field selectivity effect was weak.
[0086]
【The invention's effect】
According to the method of the present invention, it is possible to produce a visual field selective film using craze having excellent visual field selectivity.
[0087]
Further, according to the method of the present invention, since the craze is colored at the same time as the formation, the formed craze can be easily recognized, and a defective craze formation portion is found at the time of craze formation and the portion is removed, or the manufacturing conditions Etc. can be corrected. Therefore, when coloring after forming a craze, it is difficult to identify uncolored crazes, so it is not possible to find bad craze formation at the time of craze formation. It is possible to avoid such a problem that a defect is found.
[0088]
Furthermore, according to the method of the present invention, the formation of the craze and the coloration are simultaneously performed, so that the visual field selective film can be manufactured in one step, and the manufacturing process can be shortened, so that high manufacturing efficiency can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating the function of a visual field selective film produced by the method of the present invention.
FIG. 2 is a diagram for explaining a method for producing a visual field selective film of the present invention.
FIG. 3 is a diagram for explaining a method for producing a visual field selective film of the present invention.
[Explanation of symbols]
1. . . Field selective film
2. . . Craze
3. . . object
4). . . Observer
5. . . Observer
6). . . Plastic film
7). . . blade
8). . . Small diameter roller
9. . . Bending part
10. . . Coloring liquid applicator
11, 12. . . roller
13. . . Coloring liquid
14 . . Colored liquid bath

Claims (6)

  A method for producing a field-selective sheet comprising a transparent plastic film having a large number of regularly oriented crazes containing a coloring substance, comprising forming crazes having a regular direction on a plastic film, A method for producing a visual field selective film, comprising introducing a coloring substance, and forming crazes in the presence of a coloring liquid containing the coloring substance. By applying a force linearly to a plastic film to which tension is applied, a local fold is formed in the film, and the film is taken in a direction perpendicular to the fold direction of the fold in the plane of the film. The method according to claim 1, wherein a plurality of crazes having a regular direction substantially parallel to a bending direction is formed.   The craze is generated in the presence of the coloring liquid by applying the coloring liquid to the surface of the film on which the crazing is formed before forming the local bent portion on the plastic film. the method of.   3. The method according to claim 2, wherein craze is generated in the presence of the coloring liquid by forming a local fold of the plastic film in the coloring liquid bath. The plastic film laminated on the other layer is peeled off in a colored liquid bath so as to form a local fold, thereby allowing the film to have a large number of regular orientations substantially parallel to the fold direction. The method according to claim 1, wherein craze is formed.   The method according to claim 4, wherein the film is treated with a solvent and / or a surfactant before the local fold is formed in the plastic film.

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