JP3565928B2 - Manufacturing method of plastic substrate for liquid crystal display element - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method of manufacturing a plastic substrate for a liquid crystal display element, and more particularly to a method of manufacturing a plastic substrate for a liquid crystal display element that causes less loss of a base sheet and does not adversely affect the optical characteristics of the base sheet.
[0002]
[Prior art]
Plastic substrate liquid crystal display devices using plastic for the substrate are lighter and more flexible than liquid crystal display devices using glass substrates. Application to is expected.
[0003]
That is, glass is a material excellent in transparency, optical isotropy, gas barrier properties, chemical resistance, heat resistance, smoothness, dimensional stability, etc. required for a substrate of a liquid crystal display element, but has flexibility. For example, when used for a display of a portable terminal such as an electronic organizer or a notebook computer, the chip may be damaged.
[0004]
On the other hand, plastic is flexible, light in weight, and has properties such as being capable of being processed in a long length by a roll. Therefore, for example, a substrate of a liquid crystal display element used for a display of the portable terminal is used. It is attracting attention as a material. However, since the plastic sheet alone cannot satisfy the above-mentioned required properties of the substrate material, each functional film such as a gas barrier layer for imparting gas barrier properties and a hard coat layer for imparting high surface hardness is provided. Need to be laminated on plastic sheet. In particular, the gas barrier layer and the hard coat layer are generally laminated on a plastic sheet in this order, and these layers are all formed by a coating method.
[0005]
[Problems to be solved by the invention]
However, when manufacturing a plastic substrate for a liquid crystal display element by a conventional manufacturing method, after applying a functional film forming resin in a solution state directly on a plastic base sheet, heat is applied to dry a solvent component. And the heat may adversely affect the optical properties of the plastic substrate. In addition, when a plastic having poor solvent resistance is used, there is a limitation in manufacturing that a functional film-forming resin must be applied in an aqueous system, for example.
[0006]
Furthermore, in the conventional manufacturing method, coating is performed on a roll or a sheet of plastic base sheet, so if a defective portion occurs during coating, the entire plastic base sheet must be discarded. Loss of the plastic substrate sheet due to repeated coating is a major problem in manufacturing a plastic substrate for a liquid crystal display device.
[0007]
The present invention has been made based on such circumstances, and an object of the present invention is to prevent the optical characteristics of a plastic substrate sheet from being adversely affected, and to prevent the occurrence of loss of a plastic substrate sheet in a manufacturing process. It is an object of the present invention to provide a method for producing a plastic substrate sheet for a liquid crystal display element, which is not restricted by production even when a base sheet made of plastic having poor solvent resistance is used.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a method for producing a plastic substrate for a liquid crystal display element of the present invention comprises:
A method for producing a plastic substrate for a liquid crystal display element, comprising a gas barrier layer and a hard coat layer made of a urethane acrylate resin, a phenoxy ether resin or an epoxy resin laminated in this order on a base material made of a polymer material. After forming a hard coat layer on a heat-resistant support having a high surface smoothness, a gas barrier layer is formed on the hard coat layer to form a transfer laminate, and then a base material made of a polymer material is used. A structure in which the transfer laminate is adhered in a state where one surface of the substrate and the gas barrier layer of the transfer laminate face each other, and then the heat-resistant support constituting the laminate is peeled off. age,
Further, if necessary, a plasma CVD method is used to form the gas barrier layer, and by changing the mixture ratio of a gas obtained by vaporizing an organic silicon compound in the plasma CVD method, oxygen gas, and an inert gas, Forming a silicon oxide film in which the content of one or more of carbon, hydrogen, silicon and oxygen or a mixture or compound of the compounds decreases in the depth direction from the film surface; It was configured as a layer.
[0009]
[Action]
In the method for producing a plastic liquid crystal display element of the present invention, first, a heat-resistant support having high surface smoothness is prepared, and a hard coat layer is formed on the heat-resistant support having high surface smoothness. Next, a gas barrier layer is formed on the hard coat layer. Thereby, a transfer laminate in which a hard coat layer and a gas barrier layer are laminated in this order on a heat-resistant support having high surface smoothness is obtained. On the other hand, a base material made of a polymer material is prepared. Then, the base material made of the polymer material is bonded to the transfer laminate. At this time, the transfer laminate and the base material made of a polymer material are bonded together in a state where the gas barrier layer side of the transfer laminate and one surface of the base material face each other. Thus, the gas barrier layer, the hard coat layer, and the heat-resistant support having high surface smoothness are laminated in this order on the base material made of the polymer material. Thereafter, when the heat-resistant support having high surface smoothness is peeled off, a plastic substrate for a liquid crystal display element in which a gas barrier layer and a hard coat layer are laminated in this order on a base material made of a polymer material is obtained. The plastic substrate for a liquid crystal display element thus obtained has a hard coat layer with high surface smoothness. Therefore, a pair of plastic substrates for a liquid crystal display element manufactured by the method of the present invention are prepared, a transparent electrode layer is provided on the hard coat layer surface of each substrate, and the transparent electrode layer surfaces are arranged facing each other. By injecting and sealing a liquid crystal material between the substrates, it is possible to obtain a liquid crystal display element exhibiting stable performance with a constant substrate spacing. As described above, the production method of the present invention does not directly form a gas barrier layer and a hard coat layer on a base material made of a polymer material, but temporarily forms a hard surface on a heat-resistant support having high surface smoothness. After forming a coat layer and a gas barrier layer in this order to form a laminate, the laminate is adhered to a substrate made of a polymer material from the gas barrier layer side, and then the heat-resistant support having a high surface smoothness is peeled off. By removing, a plastic substrate for a liquid crystal display element in which a gas barrier layer and a hard coat layer are laminated on a substrate made of a polymer material in this order is manufactured. Therefore, according to this method, even when each layer of the gas barrier layer and the hard coat layer is formed by coating, there is no fear that the heat required for drying the solvent component adversely affects the optical characteristics of the base material made of the polymer material. In addition, even when a defective portion occurs at the time of coating, loss of the base material made of a polymer material does not occur. Moreover, according to this method, the hard coat layer, which is the outermost surface on the liquid crystal material side, is protected by the heat-resistant support having high surface smoothness during the manufacturing process, so that the hard coat layer is damaged and contaminated during the manufacturing process. Is prevented.
[0010]
In the method for manufacturing a plastic liquid crystal display element of the present invention, if necessary, a plasma CVD method is used for forming a gas barrier layer, and a gas obtained by vaporizing an organic silicon compound in this plasma CVD method and an oxygen gas are used. By changing the mixing ratio with an inert gas, the content of one or more of a mixture or compound of carbon, hydrogen, silicon and oxygen decreases in the depth direction from the film surface. An object film may be formed, and this silicon oxide film may be used as a gas barrier layer. By doing so, a gas barrier layer composed of a continuous layer of silicon oxide which is dense and has extremely high gas barrier properties and excellent impact resistance is formed. In addition, this silicon oxide film contains one or a mixture or compound of two or more of carbon, hydrogen, silicon, and oxygen, and the content thereof decreases from the film surface in the depth direction. In other words, since it is formed so that the content at the film surface is the highest and the content at the interface with the base material made of a polymer material is the lowest, the gas barrier layer surface where cracks are most likely to occur has an impact resistance While the adhesion between the gas barrier layer and the hard coat layer becomes strong.
[0011]
【Example】
Next, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1A, first, a heat-resistant support 1 having high surface smoothness is prepared. The heat-resistant support 1 needs to have high surface smoothness and excellent heat resistance. The surface smoothness is usually _Ra = 0.2 μm or less, and the heat-resistant temperature is usually 120 ° C. or more. It is. Further, the heat-resistant support 1 needs to have a property capable of being separated from the hard coat layer 2 laminated on the heat-resistant support 1.
[0012]
Examples of a material for forming the heat-resistant support 1 having the above properties include a biaxially stretched polyester film.
The thickness of the heat-resistant support 1 is usually about 25 to 200 μm.
[0013]
Next, as shown in FIG. 1B, a hard coat layer 2 is formed on the heat-resistant support 1.
The hard coat layer 2 has a high surface hardness, imparts impact resistance to the base material 4 without impairing the flexibility of the base material 4 described in detail later, and also prevents the surface of the base material 4 from being damaged or contaminated. It is a layer having an action or a function, and examples of a forming material include a urethane acrylate resin, a phenoxy ether resin, and an epoxy resin.
[0014]
It is possible to suitably employ a coating method for forming the hard coat layer 2. Specifically, any of various coating methods such as a gravure coating method, a roll coating method, a bar coating method, and a die coating method are suitable. Can be adopted.
[0015]
The thickness of the hard coat layer 2 thus formed is usually about 5 to 30 μm.
Next, as shown in FIG. 1C, a gas barrier layer 3 is formed directly on the hard coat layer 2 or via an adhesive. The adhesive includes, for example, polyester urethane-based resin, polyurethane-based resin, and the like.
[0016]
The gas barrier layer 3 is a layer having an action or function of imparting a gas barrier property to the base material 4 described later in detail, and may be applied by applying a coating method or a physical vapor deposition (PVD) method. Alternatively, a continuous layer may be formed by employing a technique such as a chemical vapor deposition (CVD) method.
[0017]
When the gas barrier layer 3 is formed by a coating method, examples of a material for forming the gas barrier layer 3 include polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, polyvinylidene chloride, and polysilazane.
[0018]
The thickness of the gas barrier layer 3 formed by the coating method is usually about 0.3 to 20 μm.
On the other hand, when the gas barrier layer 3 is formed as a continuous film, the following specific plasma CVD method using a mixed gas of a gas obtained by vaporizing an organosilicon compound, oxygen gas, and an inert gas is used. It can be suitably adopted.
[0019]
FIG. 2 is an explanatory view showing an example of a plasma CVD apparatus that can be suitably used in the method for producing a plastic substrate for a liquid crystal display element of the present invention. As shown in FIG. 2, the plasma CVD apparatus 11 includes a chamber 12, a supply roller 13, a take-up roller 14, a cooling / electrode drum 15, and auxiliary rollers 16, 16, which are disposed in the chamber 12. The electrode drum 15 is connected to a power supply 17 and the inside of the chamber 12 is configured to be set to a desired degree of vacuum by a vacuum pump 18. Further, an opening of a raw material supply nozzle 19 is provided in the vicinity of the cooling / electrode drum 15 in the chamber 12, and the other end of the raw material supply nozzle 19 is provided at a raw material vaporizing supply device 21 provided outside the chamber 12. And a gas supply device 22. Further, a magnet 23 for promoting the generation of plasma is provided near the cooling / electrode drum 15.
[0020]
When forming the gas barrier layer 3 using this plasma CVD apparatus, first, the raw material of the heat-resistant support 1 on which the hard coat layer 2 is formed is mounted on the supply roller 13 of the plasma CVD apparatus, An original transfer path is formed to reach the winding roller 14 via the cooling / electrode drum 15 and the auxiliary roller 16.
[0021]
Next, the pressure inside the chamber 12 is reduced to a degree of vacuum of 10 ⁻¹ to 10 ⁻⁸ torr, preferably 10 ⁻³ to 10 ⁻⁷ torr by the vacuum pump 18. Then, the gas obtained by vaporizing the organic silicon compound as the raw material in the raw material vaporizing supply device 21 is mixed with the oxygen gas and the inert gas supplied from the gas supply device 22, and the mixed gas is supplied to the raw material supply nozzle 19. Through the chamber 12. Here, the content of each gas in the mixed gas ranges from 1 to 40% for a gas obtained by vaporizing an organic silicon compound, 10 to 70% for an oxygen gas, and 10 to 60% for an inert gas. For example, the mixing ratio of a gas obtained by vaporizing an organic silicon compound, oxygen gas, and an inert gas can be about 1: 6: 5 to 1:17:14.
[0022]
On the other hand, since a predetermined voltage from the power supply 17 is applied to the cooling / electrode drum 15, glow discharge plasma P is generated near the opening of the raw material supply nozzle 19 in the chamber 12 and the cooling / power supply drum 15. I do. The glow discharge plasma P is derived from one or more gas components in the mixed gas. In this state, the heat-resistant support 1 on which the hard coat layer 2 is formed is transported at a constant speed, and is formed on the heat-resistant support 1 on the peripheral surface of the cooling / electrode drum 15 by the glow discharge plasma P. On the hard coat layer 2, a gas barrier layer 3 composed of a continuous layer of silicon oxide is formed. At this time, the degree of vacuum in the chamber 12 is set to 10 ^-1 to 10 ^-4 torr, preferably 10 ^-1 to 10 ^-2 torr. The transport speed of the heat-resistant support 1 on which the hard coat layer 2 is formed is 10 to 300 m / min, preferably 50 to 150 m / min.
[0023]
The heat-resistant support 1 in which the gas barrier layer 3 is formed on the hard coat layer 2 is wound up by a take-up roller 14.
In a specific plasma CVD method in which the mixing ratio of the gas obtained by vaporizing the organic silicon compound and the mixed gas of the oxygen gas and the inert gas supplied from the gas supply device 22 is changed, The mixed gas is mixed so that the content of one or more of a mixture or compound of carbon, hydrogen, silicon and oxygen contained in the continuous layer of the oxide decreases in the depth direction from the film surface. Change the mixing ratio.
[0024]
In this particular form of the gas barrier layer 3 employing the plasma CVD method, since a thin film on the hard coat layer 2 in the form of SiO _x is formed while oxidized plasma raw material gas with oxygen, which is formed The silicon oxide thin film is a dense and continuous layer with few gaps. Therefore, the barrier property of the gas barrier layer 3 composed of such a continuous layer of silicon oxide is much higher than the barrier property of the silicon oxide film formed by the conventional vacuum deposition. Barrier properties can be obtained. In addition, since the surface of the hard coat layer 2 is cleaned by the SiO _x plasma, and a polar group and free radicals are generated on the surface of the hard coat layer 2, adhesion between the formed silicon oxide thin film and the hard coat layer 2 is performed. It becomes high. Further, as described above, the degree of vacuum at the time of forming the silicon oxide thin film is 10 ^-1 to 10 ^-4 torr, and preferably 10 ^-1 to 10 ^-2 torr. Since the degree of vacuum is lower than the degree of vacuum (10 ⁻⁴ to 10 ⁻⁵ ) torr, it is possible to shorten the time for setting the vacuum state when exchanging the substrate of the heat-resistant support 1 on which the hard coat layer 2 is formed. The temperature is easily stabilized, and the film forming process is stabilized.
[0025]
Examples of the organic silicon compound to be used in the plasma CVD method include 1,1,3,3-tetramethyldisiloxane, hexamethyldisiloxane, vinyltrimethylsilane, methyltrimethoxysilane, hexamethyldisilane, methylsilane, and dimethylsilane. , Trimethylsilane, diethylsilane, propylsilane, phenylsilane, vinyltriethoxysilane, vinyltrimethoxysilane, tetramethoxysilane, tetraethoxysilane, phenyltrimethoxysilane, methylethoxysilane, octamethylcyclotetrasiloxane, and the like. Among them, 1,1,3,3-tetramethyldisiloxane and hexamethyldisiloxane are particularly preferably used. These organosilicon compounds are liquid at normal temperature and normal pressure.
[0026]
The properties of the gas barrier layer 3 formed of a continuous silicon oxide layer obtained in this manner are determined by the value of X and the layer thickness of the composition SiO _x of the silicon oxide continuous layer. A good silicon oxide continuous layer can be formed by optimizing the transport speed of the porous support 1, the electric power during plasma generation, and the mixing ratio of the mixed gas. In particular, the mixed gas is such that the content of a mixture or compound of one or more of carbon, hydrogen, silicon and oxygen is the largest at the film surface and the smallest at the interface with the polymer substrate. By changing the mixing ratio, the impact resistance is improved on the surface of the gas barrier layer where cracks are most likely to occur, while the adhesion between the gas barrier layer 3 and the hard coat layer 2 becomes strong.
[0027]
When the gas barrier layer 3 is formed by employing this specific plasma CVD method, the thickness of the gas barrier layer 3 is usually about 0.02 to 0.1 μm.
In the method of the present invention, the hard coat layer 2 and the gas barrier layer 3 are formed in this order on the heat-resistant support 1 to form the transfer laminate 5 while the base material made of a polymer material is used. Material 4 is prepared.
[0028]
As a material for forming the base material 4, for example, a polycarbonate resin, a polyether sulfone resin, a polyethylene terephthalate resin, or the like is suitably used from the viewpoint of optical characteristics required for a liquid crystal display device.
[0029]
The base material 4 is used in a sheet shape.
As shown in FIG. 1 (d), in the method of the present invention, the substrate 4 and the above-mentioned transfer laminate 5 are adhered to each other with an adhesive or a pressure-sensitive adhesive. This bonding is performed between one surface of the substrate 4 and the gas barrier layer 3 of the transfer laminate 5. In FIG. 1D, reference numeral 6 denotes an adhesive layer.
[0030]
Here, examples of the adhesive and pressure-sensitive adhesive that can be used for bonding include urethane-based adhesives and acrylic-based adhesives.
The thickness of the adhesive layer 6 made of these adhesives / adhesives is usually about 1 to 20 μm.
[0031]
As shown in FIG. 1 (e), in the method of the present invention, after bonding the base material 4 and the above-mentioned transfer laminate 5 as described above, the heat-resistant support constituting the transfer laminate 5 is formed. The body 1 is separated from the interface with the hard coat layer 2 and removed to obtain a plastic substrate 7 for a liquid crystal display element.
[0032]
The plastic substrate 7 for a liquid crystal display element thus obtained is obtained by laminating a gas barrier layer 3 having excellent barrier properties and a hard coat layer 2 having high surface smoothness on a base material 4 made of a polymer material in this order. It has the advantage of being flexible and resistant to cracking, and also satisfies the required optical performance, so that it can be used for liquid crystal display elements of portable terminals such as electronic notebooks, notebook computers, etc. It can be suitably used as a constituent substrate.
[0033]
【The invention's effect】
As described in detail above, according to the method for producing a plastic substrate for a liquid crystal display element of the present invention, a hard coat layer and a gas barrier layer are formed on a heat-resistant support having excellent surface smoothness and heat resistance. After sequentially forming a transfer laminate, the transfer laminate and a base material made of a polymer material are bonded together in a state where the gas barrier layer of the transfer laminate and one surface of the base material face each other. After that, by removing and removing the heat-resistant support constituting the transfer laminate, the gas barrier layer and the hard coat layer were transferred onto the substrate made of a polymer material. According to the method, even when each layer of the gas barrier layer and the hard coat layer is formed by coating, there is no concern that the heat required for drying the solvent component adversely affects the optical characteristics of the base material made of the polymer material. Co Even if a defective portion occurs during Ingu, loss of substrate made of a polymer material does not occur. Moreover, according to this method, the hard coat layer, which is the outermost surface on the liquid crystal material side, is protected by the heat-resistant support having high surface smoothness during the manufacturing process, so that the hard coat layer is damaged and contaminated during the manufacturing process. Is reliably prevented.
[0034]
Further, if the gas barrier layer is formed by forming a continuous layer of a specific silicon oxide on the hard coat layer by adopting a specific plasma CVD method, the gas barrier layer is dense, excellent in the barrier layer, and most cracked. It is possible to efficiently obtain a plastic substrate for a liquid crystal display device having a gas barrier layer having improved impact resistance on the outermost surface where the occurrence of cracks is likely to occur and having strong adhesion to the hard coat layer.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a method for manufacturing a plastic substrate for a liquid crystal display element of the present invention in the order of steps.
FIG. 2 is an explanatory diagram showing a configuration example of a plasma CVD apparatus that can be suitably used in the method of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Heat resistant support 2 ... Hard coat layer 3 ... Gas barrier layer 4 ... Substrate 5 ... Transfer laminate 7 ... Plastic substrate for liquid crystal display element

Claims (2)

A method for producing a plastic substrate for a liquid crystal display element, comprising a gas barrier layer and a hard coat layer made of a urethane acrylate resin, a phenoxy ether resin or an epoxy resin laminated in this order on a base material made of a polymer material. ,
After forming a hard coat layer on a heat-resistant support having a high surface smoothness, a gas barrier layer is formed on the hard coat layer to form a transfer laminate, and then a base material made of a polymer material and The transfer laminate is bonded in a state where one surface of the substrate and the gas barrier layer of the transfer laminate face each other, and then the heat-resistant support constituting the transfer laminate is peeled off. A method for producing a plastic substrate for a liquid crystal display device, characterized by comprising: By using a plasma CVD method for forming the gas barrier layer and changing the mixing ratio of a gas obtained by vaporizing an organic silicon compound, oxygen gas, and an inert gas in the plasma CVD method, carbon, hydrogen, silicon, 2. A silicon oxide film in which the content of one or more of oxygen or a mixture or compound of oxygen decreases in the depth direction from the film surface, and the silicon oxide film is used as a gas barrier layer. The method for producing a plastic substrate for a liquid crystal display element according to the above.

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