JP2013164494A - Spacer formation ink for liquid crystal display device, liquid crystal display device, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spacer formation ink that enables elastic recovery even when a load is applied on spacer resin, has excellent flexibility, and causes no low-temperature bubbles under low temperature, and provide a liquid crystal display device using the same and a method of manufacturing the same.SOLUTION: A spacer formation ink for a liquid crystal display device includes (1) a curable resin, and (2) a solvent as components; (1) the curable resin is a multifunctional epoxy resin having an epoxy equivalent of less than 200 and having three or more functional groups; and glass-transition temperature of a cured resin product is equal to or more than 250°C.

Description

  The present invention relates to a spacer forming ink for a liquid crystal display device, a liquid crystal display device, and a manufacturing method thereof.

  In recent years, a liquid crystal display device is used as a display device such as a monitor for a color television or a personal computer. In a liquid crystal display device, generally, a pair of transparent substrates having transparent electrodes and the like are arranged to face each other with a gap of 1 to 10 μm, and a liquid crystal layer is formed by enclosing a liquid crystal substance between the pair of substrates. It has a configuration. By applying an electric field to the liquid crystal layer through an electrode, the liquid crystal material is aligned, and the alignment of the liquid crystal material controls transmission / non-transmission of light from the backlight to display an image.

  If the thickness of the liquid crystal layer of the liquid crystal display device is non-uniform, display unevenness and contrast abnormality occur. Therefore, it is necessary to keep the gap between the substrates constant and make the thickness of the liquid crystal layer uniform. Therefore, conventionally, the gap between the substrates is made by a method in which beads such as silica particles, metal oxide particles, and thermoplastic resin particles having a uniform particle size distribution are spread on the substrates and these are arranged as spacers between the substrates. A method of keeping constant has been used.

  However, in the above-described conventional method using dispersed beads as spacers (particulate spacers), the beads are not fixed. Therefore, there is a problem in that the beads move due to vibration of the liquid crystal display device and display variation occurs. In addition, since it is difficult to accurately place beads at a desired position when spraying, the distribution tends to vary, and in some cases, beads are placed in the display area of the liquid crystal display device, and the beads are displayed. In some cases, it may cause display defects such as variations and light loss.

  Therefore, a method of forming a spacer on one substrate by a photolithography method using a photosensitive resin has been studied. According to this method, it is possible to form a resist pattern as a spacer at a desired position with high positional accuracy. In general, since the adhesion force of the resist pattern to the substrate is relatively high, the particulate spacer is used. Compared to the case of using, it can be improved in terms of alignment abnormality and contrast reduction.

  However, in a liquid crystal display device manufactured using spacers formed by a photolithography method, the liquid crystal flows downward during use, and the color called gravity failure is caused by the difference in the thickness of the liquid crystal layer in the vertical direction of the liquid crystal display device. The occurrence of uneven defects has been a problem. This is because the liquid crystal expands in a high temperature environment and the thickness of the liquid crystal layer increases, the spacer cannot follow the change in thickness, the spacer is separated from the substrate, and the liquid crystal that is no longer held by the spacer flows downward. Possible cause.

  To eliminate the poor gravity, the liquid crystal expands in a high-temperature environment, and when the spacer is released from the compressed state, the spacer elastically recovers to follow the change in the thickness of the liquid crystal layer. It is effective not to cause

  In addition, a liquid crystal display device manufactured using a spacer formed by a photolithography method has a liquid crystal thermally contracted in a low temperature environment and its volume is reduced. On the other hand, a spacer whose thermal expansion coefficient is lower than that of liquid crystal is not thermally contracted. The layer thickness is retained. As a result, dissolved air in the liquid crystal is precipitated to generate bubbles in order to compensate for the lack of volume associated with the thermal contraction of the liquid crystal. This phenomenon is called low-temperature foaming and is a factor that impairs the reliability of the liquid crystal display device.

  In order to eliminate low-temperature foaming, it is effective that when the liquid crystal thermally shrinks in a low-temperature environment, the spacer flexibly compresses and deforms to follow the change in the thickness of the liquid crystal layer and does not decrease the internal pressure of the liquid crystal cell ( Patent Documents 1 and 2).

JP 2008-003261 A JP 2008-292770 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a manufacturing method for forming a spacer with an ink containing a resin and a solvent that dissolves the resin, which does not substantially contain solid particles. It is an object of the present invention to provide a spacer-forming ink that recovers elastically even when a load is applied to the spacer resin, is excellent in flexibility, and does not generate low-temperature bubbles even at a low temperature in a liquid crystal cell produced using the spacer. It is another object of the present invention to provide a liquid crystal display device having a spacer for a liquid crystal display device using the spacer forming ink and a method for manufacturing the same.

In the case of forming a spacer for a liquid crystal display device by removing the solvent from droplets composed of an ink containing a resin and a solvent in which the resin is dissolved substantially free of solid particles, the resin composition functions as a spacer. For this reason, as in the case of the spacer formed by the photolithography method, it is a problem to suppress poor gravity under a high temperature environment and low temperature foaming under a low temperature environment.
In order to solve the above-mentioned problems, it is necessary that the resin has excellent resilience from compression deformation and has high flexibility.
In the present invention, the elastic recovery rate of the spacer resin at a maximum load of 50 mN is 90% or more, excellent in flexibility, and the liquid crystal cell produced using the spacer does not generate low-temperature bubbles when stored at −30 ° C. In addition to providing ink, a liquid crystal display device using a spacer forming ink and a manufacturing method thereof are provided.
In order to achieve the above object, in the present invention, (1) a curable resin, (2) a spacer forming ink for a liquid crystal display device containing a solvent as a component, and (1) a curable resin, Provided is a spacer-forming ink for a liquid crystal display device, which is a polyfunctional epoxy resin having an epoxy equivalent of less than 200 and a trifunctional or higher functionality, and having a glass transition temperature of a resin cured product of 250 ° C. or higher.
In the spacer forming ink for a liquid crystal display device of the present invention, it is preferable that the surface shape of the resin cured product of the formed spacer is a convex curved surface.

  The spacer forming ink for a liquid crystal display device of the present invention has a high crosslink density of a cured resin made of a cured resin composition and a high elastic recovery from compression deformation. The glass transition temperature tends to increase as the resin composition has a higher crosslink density. When the resin composition is 250 ° C. or higher, the elastic recovery rate is 90% or higher during a compression test at a maximum load of 50 mN. Moreover, it is preferable to use the condensate of phenols and aldehydes as a hardening | curing agent of a polyfunctional epoxy resin for the spacer formation ink for liquid crystal display devices.

  In general, a resin composition having a high crosslink density is hard and has low flexibility, and therefore easily foams in a low temperature environment. Since the resin cured product of the resin composition formed using the spacer-forming ink for the liquid crystal display device of the present invention is a semi-elliptical sphere and the surface shape is a convex curved surface, the contact between the resin composition and the substrate near the top of the resin composition The area is small, and the load density applied to the resin composition during compression is high. For this reason, when the same compressive load is applied, the load density is higher than that of a photo spacer whose shape near the apex is nearly flat, and the shape is easily deformed flexibly. For this reason, even if it is a resin composition with a high crosslinking density, it has the softness | flexibility sufficient to suppress low temperature foaming.

  The resin in the spacer forming ink for a liquid crystal display device is preferably a thermosetting resin. Since the viscosity of the thermosetting resin before curing is relatively low, the viscosity of the ink is reduced by using the thermosetting resin, and a more stable ejection property can be obtained. The spacer for a liquid crystal display device formed by ejecting ink is formed by heating the droplet on the substrate to remove the solvent from the droplet and curing the thermosetting resin.

  In the spacer forming ink for a liquid crystal display device of the present invention, the thermosetting resin preferably contains the epoxy resin and its curing agent. By appropriately selecting the type of epoxy resin or curing agent, the cured product constituting the spacer can have desired physical properties relatively easily. The epoxy resin is a polyfunctional epoxy resin having an epoxy equivalent of less than 200 and a tri- or higher functionality from the viewpoint of crosslink density. When the epoxy equivalent exceeds 200, the crosslink density decreases due to the increase in molecular weight between crosslink points. On the other hand, when the number of functional groups is 2 or less, the crosslinking density is low because there are few crosslinking points.

  The spacer forming ink for a liquid crystal display device of the present invention contains substantially no solid particles. “Substantially no solid particles” means that no single particles are contained that can maintain the thickness of the liquid crystal layer of the liquid crystal display device. Thereby, the positional accuracy of the spacer for liquid crystal display devices formed can be improved.

  In another aspect, the present invention relates to a method for manufacturing a spacer for a liquid crystal display device. In the present invention, a droplet made of an ink containing a curable resin and a solvent in which the resin is dissolved and substantially not containing solid particles is printed on a substrate by an inkjet method, and the solvent is removed from the droplet on the substrate. A method for manufacturing a spacer for a liquid crystal display device, wherein the spacer is removed to form a spacer disposed at a predetermined position on the substrate, wherein the resin is an epoxy equivalent of less than 200 and is a polyfunctional epoxy resin having three or more functions. A method for producing a spacer for a liquid crystal display device in which the glass transition temperature of the cured resin is 250 ° C. or higher is provided. In this production method, the surface shape of the cured resin (cured resin composition) is preferably a convex curved surface.

  In still another aspect, the present invention relates to a method of manufacturing a liquid crystal display device including a pair of substrates arranged opposite to each other, a liquid crystal layer disposed between the pair of substrates, and a spacer for a liquid crystal display device. The manufacturing method of the liquid crystal display device according to the present invention includes the step of forming the spacer for liquid crystal display device on at least one substrate by the method for manufacturing the spacer for liquid crystal display device according to the present invention. That is, the present invention is a method of manufacturing a liquid crystal display device including a pair of substrates arranged opposite to each other, a liquid crystal layer disposed between the pair of substrates, and a spacer for a liquid crystal display device, and has a curability. A droplet made of an ink containing a resin having a solvent and a solvent that dissolves the resin and substantially free of solid particles is printed on the substrate by an ink jet method, and the solvent is removed from the droplet on the substrate to obtain a predetermined on the substrate. A method of manufacturing a liquid crystal display device including a step of forming a spacer having a convex curved surface at the position is provided.

  According to the manufacturing method of the present invention, a spacer for a liquid crystal display device having excellent elastic recovery from compression deformation and sufficient flexibility can be formed with sufficiently excellent positional accuracy. Moreover, such a spacer for a liquid crystal display device can be formed by a simple process.

  In still another aspect, the present invention relates to a liquid crystal display device. A liquid crystal display device according to the present invention includes a pair of substrates disposed to face each other, a liquid crystal layer disposed between the pair of substrates, and a spacer for a liquid crystal display device. The liquid crystal display device spacer is formed by the above liquid crystal display device spacer forming ink and manufacturing method according to the present invention.

  In the liquid crystal display device according to the present invention, spacers that are excellent in elastic recovery from compression deformation and have sufficient flexibility are arranged with sufficiently excellent positional accuracy. For this reason, display defects such as poor gravity and low-temperature foaming can be sufficiently suppressed.

  According to the present invention, there is provided a spacer forming ink for a liquid crystal display device that can form a spacer for a liquid crystal display device that is excellent in elastic recovery from compression deformation and has sufficient flexibility to suppress low-temperature foaming. can do. Moreover, the manufacturing method of the spacer for liquid crystal display devices using this ink, a liquid crystal display device provided with the spacer for liquid crystal display devices formed by this manufacturing method, and its manufacturing method can be provided.

It is a schematic cross section which shows one Embodiment of the spacer for liquid crystal display devices formed on the board | substrate using the ink for spacer formation for liquid crystal display devices of this invention. It is a schematic cross section which shows another embodiment of the spacer for liquid crystal display devices formed on the board | substrate using the ink for spacer formation for liquid crystal display devices of this invention. FIG. 3 is a top view of the spacer of FIG. 2. It is a schematic cross section which shows one Embodiment of the liquid crystal display device of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a spacer for a liquid crystal display device formed by the method for manufacturing a spacer for a liquid crystal display device of the present invention. The liquid crystal display device spacer 11 made of the resin layer 20 is provided on the substrate 23. Hereinafter, a method for forming the liquid crystal display device spacer 11 will be described.

  In the method for forming a spacer for a liquid crystal display device according to this embodiment, first, a spacer forming ink for a liquid crystal display device that contains a resin and a solvent and does not substantially contain solid particles is formed on a substrate 23 used in the liquid crystal display device. Print by inkjet method. Then, for example, the resin layer 20 can be formed by removing the solvent by heat treatment or the like. As a result, the liquid crystal display device spacer 11 made of the resin layer 20 can be formed on the substrate 23. The height H of the spacer 11 is preferably 2.0 to 5.0 μm, and the diameter of the spacer 11 is preferably 5 to 50 μm. As in the present embodiment, the surface shape of the spacer for a liquid crystal display device is preferably a convex curved surface.

  As the ink jet method, for example, a general discharge method such as a piezo method that discharges a liquid by vibration of a piezo element or a thermal method that discharges a liquid by utilizing expansion of the liquid by rapid heating can be used. In order to carry out such an ink jet method, for example, a normal ink jet apparatus can be used.

  As a method of removing the solvent after the ink has landed on the substrate 23, for example, a heat treatment method of heating the substrate or blowing hot air can be employed. Such heat treatment can be performed, for example, at a heating temperature of 150 to 250 ° C. and a heating time of 0.2 to 1.0 hour. When a thermosetting resin is used as the resin, the resin can be cured after removing the solvent or simultaneously with removing the solvent.

  FIG. 2 is a schematic cross-sectional view showing another embodiment of a spacer for a liquid crystal display device formed on a substrate by the method for manufacturing a spacer for a liquid crystal display device of the present invention. The spacer 12 for a liquid crystal display device in which the resin layer 20 and the resin layer 22 are laminated in this order is provided on the substrate 23. Hereinafter, a method for forming the liquid crystal display device spacer 12 will be described.

  First, on the resin layer 20 formed on the substrate 23 in FIG. 1, a spacer forming ink for a liquid crystal display device containing a resin and a solvent and substantially not containing solid particles is printed by an inkjet method. That is, the spacer forming ink for a liquid crystal display device is printed at the same position as the position where the resin layer 20 is formed on the substrate 23. The ink may have the same composition as the ink used for forming the resin layer 20 or a different composition. As described above, the resin layer 22 can be formed on the resin layer 20 by printing the ink on the resin layer 20 and then removing the solvent in the same manner as when forming the resin layer 20. As a result, the liquid crystal display device spacer 12 in which the resin layer 20 and the resin layer 22 are laminated in this order on the substrate 23 as shown in FIG. 2 can be formed.

  FIG. 3 is a top view of the spacer 12 of FIG. The resin layer 22 is provided so as to cover the resin layer 20 (FIG. 2). Thus, the spacer forming ink of the present invention can be ejected one or more times in one forming region. Thereby, the spacer for liquid crystal display devices which can respond easily to the gap height of the liquid crystal layer in a wide range can be formed.

  Here, the board | substrate 23 is a board | substrate used for a liquid crystal display device, and can use the thing which has an electrode and an orientation layer, for example in the surface side in which the spacer 11 (12) for liquid crystal display devices is formed. The spacer forming ink for a liquid crystal display device is preferably ejected onto the surface of one of the two substrates opposed to each other in the liquid crystal display device, and the region where the spacer is arranged is a black matrix of a color filter. It is preferable to be on a non-display area.

  In this embodiment, after the spacer forming ink is printed on the substrate 23, the heat treatment is performed to once form the resin layer 20. However, after the spacer forming ink for the liquid crystal display device is printed on the substrate 23, the heating is performed. The resin layer 20 and the resin layer 22 may be formed at the same time by printing the spacer forming ink for a liquid crystal display device on the same position without performing the treatment, and then removing the solvent by a heat treatment or the like. Further, a spacer forming ink for a liquid crystal display device containing a resin and a solvent and substantially not containing solid particles is further printed on the resin layer 22 by an inkjet method to remove the solvent. A resin layer may be formed. In this way, by printing the ink on the resin layer 22 and removing the solvent, a spacer for a liquid crystal display device composed of three or more resin layers can be formed on the substrate 23.

  Next, the spacer formation ink for liquid crystal display devices used for the manufacturing method of the spacer for liquid crystal display devices is demonstrated in detail. In the method for producing a spacer for a liquid crystal display device of the present invention, an ink containing a resin and a solvent in which the resin is dissolved and substantially free of solid particles is used. Here, “substantially does not contain” means that a single particle does not contain particles that can maintain the thickness of the liquid crystal layer of the liquid crystal display device.

  In the spacer forming ink for a liquid crystal display device of this embodiment, that is, the ink, it is preferable that the resin is uniformly dissolved in the solvent. Here, “the resin is uniformly dissolved” means that the solid content of the spacer to be filtered when the ink is filtered at room temperature (15 to 25 ° C.) with a 1 μm aperture filter. It means less than 0.3% by mass with respect to the ink mass.

  The spacer forming ink for a liquid crystal display device of this embodiment preferably has a surface tension of 20 mN / m or more. When the surface tension of the spacer forming ink for liquid crystal display device is less than 20 mN / m, the ink droplet tends to spread after landing on the substrate, and there is a tendency that the spacer cannot be reliably formed in the non-display area of the narrow width of the liquid crystal display device. is there. The surface tension of the liquid crystal display device spacer forming ink is more preferably in the range of 20 to 80 mN / m. This is because when the surface tension of the ink exceeds 80 mN / m, the ink jet nozzles tend to be clogged.

  The viscosity of the liquid crystal display device spacer-forming ink of this embodiment is preferably 50 mPa · s or less at 25 ° C. If the viscosity of the spacer forming ink for liquid crystal display devices is 50 mPa · s or less, it is possible to more reliably prevent the occurrence of non-ejection nozzles during nozzle printing and the occurrence of nozzle clogging. The viscosity of the spacer-forming ink for liquid crystal display devices is more preferably 1.0 to 30 mPa · s at 25 ° C. By setting the ink viscosity within the above range, there is a tendency that the droplet diameter can be reduced and the landing diameter of the ink can be further reduced.

The vapor pressure at 25 ° C. of the solvent contained in the spacer-forming ink for liquid crystal display devices is preferably less than 1.34 × 10 ³ Pa. With such a solvent, an increase in ink viscosity due to volatilization of the solvent can be suppressed. For example, when an ink having a vapor pressure of 1.34 × 10 ³ Pa or more is used, the ink droplets are easily dried, and it becomes difficult to eject the droplets from the nozzles of the inkjet head, resulting in clogging of the inkjet head. It tends to be easier. By making the vapor pressure of the solvent contained in the spacer forming ink less than 1.34 × 10 ³ Pa, the above-mentioned problems can be avoided. Note that a solvent having a vapor pressure of less than 1.34 × 10 ³ Pa and a solvent having a vapor pressure of 1.34 × 10 ³ Pa or more may be used in combination, but in that case, the vapor pressure is 1.34 × The mixing ratio of the solvent of 10 ³ Pa or more is preferably 60% by mass or less, more preferably 50% by mass or less, and further preferably 40% by mass or less, based on the mass of the total amount of the solvent. Various solvents can be used as long as the vapor pressure is in a desired range and the insulating resin is dispersed or dissolved.

Specific examples of the solvent having a vapor pressure of less than 1.34 × 10 ³ Pa at 25 ° C. include γ-butyrolactone, cyclohexanone, N-methyl-2-pyrrolidone, anisole, ethylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, Examples include triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol dimethyl ether. Specific examples of the solvent having a vapor pressure at 25 ° C. of 1.34 × 10 ³ Pa or more include methyl ethyl ketone, methyl isobutyl ketone, toluene, isopropyl alcohol and the like. These solvents can be used alone or in combination of two or more.

  The content ratio of the solvent in the ink is not particularly limited, and it is preferable to appropriately adjust the ink so that the viscosity and the surface tension at 25 ° C. are within the above ranges. It is preferable to set it as 99 mass%.

  The resin contained in the spacer forming ink for a liquid crystal display device is a curable resin, and is a polyfunctional epoxy resin having an epoxy equivalent of less than 200 and a trifunctional or higher functionality. A material that exhibits electrical insulation and can be attached to a substrate within a range that does not impair the crosslinking density and Tg by using a polyfunctional epoxy resin. For example, epoxy resins other than those described above, phenol resins, polyimide resins , Polyamide resin, polyamideimide resin, silicone-modified polyamideimide resin, polyester resin, cyanate ester resin, BT resin, acrylic resin, melamine resin, urethane resin, alkyd resin, etc., alone or in combination of two or more May be.

  In the case of using a polyfunctional epoxy resin having an epoxy equivalent of less than 200 and a trifunctional or higher and other thermosetting resins as the resin, monomers, oligomers, etc. are dissolved in a solvent as necessary and printed on the substrate. The solvent can be removed and / or the resin can be cured by heat treatment. The spacer forming ink for a liquid crystal display device may contain a curing agent and, if necessary, a curing accelerator, a coupling agent, an antioxidant, and a filler.

The polyfunctional epoxy resin used in the present invention has three or more epoxy groups in one molecule. For example, 1,1,1-tris (4-hydroxyphenyl) methane, 4,4- (1- (4 Epoxy resin obtained by glycidylation of trisphenols such as (1- (4-hydroxyphenyl) -1-methylethyl) phenyl) ethylidene) bisphenol; 1,1,2,2, -tetrakis (4-hydroxyphenyl) ethane An epoxy resin obtained by glycidylating tetrakisphenols such as phenol novolak, cresol novolak, bisphenol A novolak, brominated phenol novolak, brominated bisphenol A novolak, naphthol novolak, phenol-cresol co-condensed novolak, naphthol-phenol co-condensed novolak, Naphthol-Crezo Novolac-type epoxy resin obtained by glycidylating novolaks such as co-condensed novolaks; naphthol-aralkyl-type epoxy resin obtained by glycidylating naphthol aralkyl resins; An epoxy resin etc. are mentioned.
Moreover, a polyfunctional glycidyl ether type epoxy resin, a polyfunctional glycidyl amine type epoxy resin, etc. can be illustrated. Examples of the polyfunctional glycidyl ether type epoxy resin include triphenyl glycidyl ether and tetraphenyl glycidyl ether ethane, and a hydrophobic group such as a t-butyl group can be introduced into the molecule. Examples of the polyfunctional glycidylamine type epoxy resin include triglycidylaminophenol, triglycidyl isocyanurate, tetraglycidylmetaxylenediamine, and tetraglycidylaminodiphenylmethane. These are trifunctional, tetrafunctional, etc., and can increase the crosslinking density by increasing the amount of epoxy groups in the composition.

  Examples of the curing agent used together with the epoxy resin include amines such as diethylenetriamine, triethylenetetramine, metaxylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, m-phenylenediamine, and dicyandiamide; phthalic anhydride, tetrahydrophthalic anhydride, hexahydro Phthalic anhydride, methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, methyl nadic anhydride, pyromellitic anhydride, trimellitic anhydride and other acid anhydrides, imidazole, 2-ethylimidazole, 2-ethyl-4- Methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 4,5-diphenylimidazole, -Methylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline, 2-heptadecylimidazoline, 2-isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole, 2-ethylimidazoline, 2-isopropyl Imidazoles such as imidazoline, 2,4-dimethylimidazoline, 2-phenyl-4-methylimidazoline; imidazoles whose imino group is masked with acrylonitrile, phenylene diisocyanate, toluidine isocyanate, naphthalene diisocyanate, methylene bisphenyl isocyanate, melamine acrylate, etc. Phenols such as bisphenol F, bisphenol A, bisphenol S, and polyvinylphenol; phenol, cresol, Le Kill phenol, catechol, bisphenol F, bisphenol A, etc. condensates and their halides and aldehydes such as phenol with formaldehyde and salicylaldehyde, such as bisphenol S and the like. Among these, from the viewpoint of heat resistance and adhesiveness, a condensate of phenols and aldehydes is preferable. These compounds may have any molecular weight, and these may be used alone or in combination of two or more.

  The content ratio of the insulating resin (polyfunctional epoxy resin, curing agent, etc.) in the spacer forming ink for liquid crystal display devices is appropriately adjusted so that the viscosity and surface tension of the ink at 25 ° C. are within the above ranges. However, it is usually preferably 1 to 50% by mass with respect to the ink mass.

  Next, the liquid crystal display device of the present invention will be described. The liquid crystal display device according to the present invention includes a pair of substrates arranged opposite to each other, a liquid crystal layer made of a liquid crystal material sealed between the pair of substrates, and a gap between the substrates in order to keep the thickness of the liquid crystal layer constant. And a spacer for a liquid crystal display device arranged. The liquid crystal display device spacer is formed at a desired position on the substrate by the ink jet printing method using the liquid crystal display device spacer forming ink of the present invention. Here, the spacer for the liquid crystal display device is obtained by, for example, applying the ink for forming the spacer for the liquid crystal display device to a desired position on the substrate by the ink jet printing apparatus, and curing the resin and / or removing the solvent by heat treatment. Can be formed.

  FIG. 4 is a schematic cross-sectional view showing an embodiment of the liquid crystal display device of the present invention. As shown in FIG. 4, the liquid crystal display device 1 has a pair of substrate members 6 a and 6 b disposed to face each other. The substrate member 6a includes an electrode 2a, a color filter 7, a substrate 3a, a retardation plate 8, and a polarizing plate 5a, which are stacked in this order. Moreover, the board | substrate member 6b consists of the electrode 2b, the board | substrate 3b, and the polarizing plate 5b, and these are laminated | stacked in this order. Further, a backlight 9 is disposed outside the polarizing plate 5b in the substrate member 6b. Further, alignment layers 17a and 17b are laminated on the side of the substrate members 6a and 6b where the electrodes 2a and 2b are formed. The liquid crystal layer 18 is sandwiched between the substrate members 6a and 6b via the alignment layers 17a and 17b. And the sealing material 13 is provided between the board | substrate members 6a and 6b in the peripheral part of the liquid-crystal layer 18, Thereby, the board | substrate members 6a and 6b are couple | bonded.

  In such a liquid crystal display device, as shown in FIG. 4, the liquid crystal display device spacer 10 is disposed at a predetermined position of the liquid crystal display device 1 in order to keep the thickness of the liquid crystal layer 18 constant. From the viewpoint of displaying a high-quality image, the liquid crystal display device spacer 10 is preferably disposed at a position other than the display dot portion which is a light transmitting portion.

  In addition, the liquid crystal display device spacers 10 are preferably arranged at equal intervals over the entire screen display area. Since the liquid crystal display device spacer 10 is formed by the ink jet printing method using the liquid crystal display device spacer forming ink of the present invention, the liquid crystal display device spacer 10 is disposed with sufficiently high positional accuracy over the entire screen display area. Display defects such as variations and light leakage can be sufficiently suppressed.

  In such a liquid crystal display device, droplets made of ink containing a resin and a solvent and substantially not containing solid particles are printed on the alignment layer 17b provided on the substrate 3b by an ink jet method to remove the solvent. By doing so, it can be manufactured by a manufacturing method including a step of forming the spacer 10 for a liquid crystal display device. The spacer 10 for a liquid crystal display device can be adjusted to a desired height by forming the above-described ink by printing two or more times by an inkjet method.

  Note that the substrate members 6a and 6b shown in FIG. 4 each have a structure in which the above-described layers are stacked, but it is not always necessary to stack all of them. In addition, the substrate members 6a and 6b may be further provided with an insulating layer, a black matrix layer, a buffer material layer, a TFT, and the like as necessary.

  As the electrodes 2a and 2b, transparent electrodes such as tin-doped indium oxide (ITO) can be used. Moreover, as a board | substrate 3a, 3b, a plastic plate, a glass plate, etc. can be illustrated. As the color filter 7, the retardation plate 8, the polarizing plates 5 a and 5 b, and the backlight 9, known ones can be used. The alignment layers 17a and 17b can also be formed using a known liquid crystal aligning agent.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention more concretely, this invention is not limited to a following example. In addition, when the spacer formation ink for liquid crystal display devices of each Example is separated by filtration, the amount of solid content to be filtered is filtered at room temperature (25 ° C.) using a filter having an opening of 1 μm. The mass after the filtered solid content was dried at a temperature of 200 ° C. for 1 hour was measured.

(Preparation of spacer forming ink 1 for liquid crystal display device)
11.9 g of tetrafunctional naphthalene type epoxy resin (manufactured by DIC Corporation, trade name: HP4710, epoxy equivalent 170), 8.0 g of bisphenol novolac resin (trade name: VH-4170, manufactured by DIC Corporation), 2-ethyl-4 -0.1 g of methylimidazole (trade name: 2E4MZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was dissolved in 80.0 g of γ-butyrolactone as a solvent to prepare spacer forming ink 1 for a liquid crystal display device.

  The amount of solid content to be filtered off of the prepared ink was 0.001% by mass.

(Preparation of spacer forming ink 2 for liquid crystal display device)
Triphenylmethane type epoxy resin (Mitsubishi Chemical Corporation, trade name: 1032H60, epoxy equivalent 169) 11.9 g, bisphenol novolak resin (DIC Corporation, trade name: VH-4170) 8.0 g, 2-ethyl- 0.1 g of 4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name: 2E4MZ) was dissolved in 80.0 g of γ-butyrolactone as a solvent to prepare spacer forming ink 2 for a liquid crystal display device.

  The amount of solid content to be filtered off of the prepared ink was 0.001% by mass.

(Preparation of spacer forming ink 3 for liquid crystal display device)
11.9 g of triphenylmethane type epoxy resin (manufactured by Mitsubishi Chemical Corporation, trade name: 1032H60, epoxy equivalent 169), 8.0 g of bisphenol novolac resin (trade name: KH-6021, manufactured by DIC Corporation), 2-ethyl- 4-methylimidazole (trade name: 2E4MZ, manufactured by Shikoku Kasei Kogyo Co., Ltd.) (0.1 g) was dissolved in 80.0 g of γ-butyrolactone as a solvent to prepare spacer forming ink 3 for liquid crystal display devices.

  The amount of solid content to be filtered off of the prepared ink was 0.001% by mass.

(Preparation of spacer forming ink 4 for liquid crystal display device)
Bisphenol A novolac type epoxy resin (DIC Corporation, average functional number 5.6, trade name: N865, epoxy equivalent 208) 12.8 g, bisphenol novolak resin (DIC Corporation, trade name: VH-4170) 7. 0 g, 0.1 g of 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name: 2E4MZ) was dissolved in 80.0 g of γ-butyrolactone as a solvent, and a spacer forming ink 4 for a liquid crystal display device was obtained. Prepared.

  The amount of solid content to be filtered off of the prepared ink was 0.001% by mass.

(Preparation of spacer forming ink 5 for liquid crystal display device)
13.6 g of bisphenol A novolac type epoxy resin (manufactured by DIC Corporation, average functional number 5.6, trade name: N865, epoxy equivalent 208), triphenolalkane type phenol resin (made by Meiwa Kasei Co., Ltd., trade name: MEH-) 7500) 6.3 g, 2-ethyl-4-methylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., trade name: 2E4MZ) 0.1 g was dissolved in 80.0 g of γ-butyrolactone as a solvent, and a spacer for a liquid crystal display device Forming ink 5 was prepared.

  The amount of solid content to be filtered off of the prepared ink was 0.001% by mass.

Example 1
A spacer forming ink for a liquid crystal display device is filtered through a membrane filter having an opening of 1 μm to remove foreign matter, and a piezo-type inkjet device (trade name: Nano Printer 1000, manufactured by Microjet Co., Ltd.) equipped with a head having a diameter of 50 μm. ).

(Printing of spacer forming ink for liquid crystal display device, formation of spacer for liquid crystal display device)
Using the inkjet device, a liquid crystal display device has a droplet capacity of 15 pL at intervals of 150 μm on the surface of the glass plate (substrate) on which the alignment film for VA (Vertical Alignment) liquid crystal is formed. The spacer forming ink was printed. After the ink was printed once, the substrate was quickly transferred onto a hot plate heated to 180 ° C., and dried and cured for 30 minutes to form a spacer.

(Evaluation of landing position accuracy)
The formed spacer for a liquid crystal display device was observed with a metallographic microscope, and an image was taken in a state where a total of 80 spacers of 8 rows × 10 points were included in one visual field. After that, a grid pattern image with a width of 50 μm prepared in advance is superimposed on this image so that the center of an arbitrary spacer is an arbitrary intersection of the grid pattern on the screen of a personal computer. Was evaluated (n = 80). The evaluation results were as shown in Table 1.

<Evaluation criteria for landing position accuracy and satellite generation rate>
A: The ratio of the spacers arranged so that the center point of the spacer for liquid crystal display device is located within the frame of the lattice is 98% or more. B: The center point of the spacer for liquid crystal display device is located within the frame of the lattice. Less than 98% of spacers placed

(Evaluation of adhesion)
After a commercially available cellophane tape was strongly pressure-bonded to the formed spacer for a liquid crystal display device, the cellophane tape was peeled off at once, and the presence or absence of the spacer was checked to evaluate the adhesion. The evaluation criteria for adhesion are as follows. The evaluation results of adhesion were as shown in Table 1.

<Adhesion evaluation criteria>
A: The spacer for liquid crystal display devices is not peeled off at all by the tape test.
B: At least a part of the spacer for liquid crystal display device is peeled off by the tape test.

(Evaluation of spacer height for liquid crystal display devices)
The height of the formed spacer for the liquid crystal display device was measured by a three-dimensional non-contact surface shape measurement system (trade name: Vertscan 2.0) manufactured by Ryoka System Co., Ltd. (n = 96), and the average value and standard of the measured values Deviation was determined. The evaluation results were as shown in Table 1.

(Evaluation of spacer diameter)
The diameter of the formed spacer for a liquid crystal display device was measured by observing with a microscope (n = 96). The evaluation results were as shown in Table 1.

(Evaluation of glass transition temperature of spacer resin composition for liquid crystal display device)
A spacer forming ink for a liquid crystal display device was applied onto a glass plate by an applicator and heated and dried at 180 ° C. to prepare a cured resin film. The glass transition temperature of the resin film obtained by peeling this cured resin film from the glass plate was measured in a tensile mode using RSAIII (manufactured by TA Instruments). The test conditions were a frequency of 1 Hz, a measurement temperature of 20 to 300 ° C., and a heating rate of 5 ° C./min. The evaluation results were as shown in Table 1.

(Evaluation of elastic recovery rate of spacer)
In a room adjusted to a temperature of 25 ° C., the spacer for the liquid crystal display device is compressed at a load application speed of 2.5 mN / s, held at a load of 50 mN for 5 seconds, and the load is removed at a load application speed of 2.5 mN / s to remove elasticity. The recovery deformation of the spacer height due to recovery was measured. The amount of deformation of the spacer when the compression deformation during this time becomes maximum is H1, and the amount of deformation of the spacer when the load is removed is H2. The elastic recovery rate of the spacer was calculated by the following formula (1) using the obtained value.
Elastic recovery factor = [(H1-H2) / H1] × 100
The evaluation results were as shown in Table 1.

(Production of simple liquid crystal cell for reliability test)
A spacer pattern ink was printed on an ITO glass substrate (100 mm × 100 mm) coated with an alignment film for VA liquid crystal under predetermined conditions to form a spacer pattern. A sealing material mixed with beads having a predetermined particle diameter was applied to the substrate side on which the spacers were formed. The seal pattern was a double seal drawing a square at 4.0 mm and 7.5 mm positions from the substrate edge. 22.1 mg of liquid crystal material was dropped inside the double seal, and then the ITO glass substrate was made to face, and alignment and superposition were performed in a vacuum chamber under reduced pressure. The cell where the superposition was completed was taken out from the decompression chamber to the atmospheric pressure. The above operation was performed using a homemade liquid crystal cell laminating apparatus. Thereafter, ultraviolet irradiation (6000 mJ / cm ² ) and heating (120 ° C./1 h) were performed to cure the sealing material and obtain a cell in which liquid crystal was sealed.

(Low temperature reliability test)
The prepared liquid crystal cell was allowed to stand for 500 hours in an environment of −30 ° C., and then the presence or absence of bubbles was examined with an optical microscope. The evaluation results were as shown in Table 1.

(Example 2)
A liquid crystal display spacer was formed on the substrate in the same manner as in Example 1 except that the liquid crystal display spacer formation ink 2 was used in place of the liquid crystal display spacer formation ink 1, and each evaluation was performed. . The evaluation results were as shown in Table 1.

(Example 3)
A liquid crystal display device spacer was formed on the substrate in the same manner as in Example 1 except that the liquid crystal display device spacer formation ink 3 was used instead of the liquid crystal display device spacer formation ink 1, and each evaluation was performed. . The evaluation results were as shown in Table 1.

(Comparative Example 1)
A liquid crystal display device spacer was formed on the substrate in the same manner as in Example 1 except that the liquid crystal display device spacer formation ink 4 was used instead of the liquid crystal display device spacer formation ink 1, and each evaluation was performed. . The evaluation results were as shown in Table 1.

(Comparative Example 2)
A liquid crystal display device spacer was formed on the substrate in the same manner as in Example 1 except that the liquid crystal display device spacer formation ink 5 was used instead of the liquid crystal display device spacer formation ink 1, and each evaluation was performed. . The evaluation results were as shown in Table 1.

  In Examples 1 to 3, which is a polyfunctional epoxy resin having an epoxy equivalent of less than 200 and a trifunctional or higher functionality, and the glass transition temperature of the cured resin is 250 ° C. or higher, the elastic recovery rate of the spacer resin is 90% or higher, and − Low temperature foaming of the liquid crystal cell stored at 30 ° C. was not generated and was good.

  On the other hand, although it is a polyfunctional type epoxy resin more than trifunctional, and Comparative Examples 1 and 2 exceeding the epoxy equivalent 200, the low temperature foaming of the liquid crystal cell stored at −30 ° C. did not occur, but the elastic recovery rate of the spacer resin Was less than 90%.

1: Liquid crystal display device 2a, 2b: Electrode 3a, 3b: Substrate 5a, 5b: Polarizing plate 6a, 6b: Substrate member 7: Color filter 8: Retardation plate 9: Backlight 10: Spacer for liquid crystal display device 11: Liquid crystal Display device spacer 12: Liquid crystal display device spacer 13: Sealing material 17a, 17b: Alignment layer 18: Liquid crystal layer 20, 22: Resin layer 23: Substrate 23a: Substrate surface

Claims (5)

  (1) A curable resin, (2) a spacer-forming ink for a liquid crystal display device containing a solvent as a component, and (1) the curable resin has an epoxy equivalent of less than 200 and a trifunctional or higher functionality. A spacer-forming ink for a liquid crystal display device, which is a functional epoxy resin and has a glass transition temperature of 250 ° C. or higher of the cured resin.   Furthermore, the spacer formation ink for liquid crystal display devices of Claim 1 which contains a hardening | curing agent and a hardening | curing agent is a condensate of phenols and aldehydes.   A method of manufacturing a liquid crystal display device comprising a pair of substrates arranged opposite to each other, a liquid crystal layer and a spacer for the liquid crystal display device disposed between the pair of substrates, and comprising a curable resin and dissolving the same A droplet made of ink containing a solvent that does not substantially contain solid particles is printed on a substrate by an ink jet method, and the solvent is removed from the droplet on the substrate so that the surface shape is at a predetermined position on the substrate. A manufacturing method of a liquid crystal display device including a step of forming a spacer which is a convex curved surface.   The method for manufacturing a liquid crystal display device according to claim 3, wherein the ink is a spacer forming ink for a liquid crystal display device according to claim 1.   A liquid crystal display device formed by the manufacturing method according to claim 3.

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