JPH06212101A - Method of destaticizing liquid crystal substrate - Google Patents

Abstract

PURPOSE:To destaticize temporarily a liquid crystal substrate by forming an antistatic resin film on the surface of the substrate, curing the film by irradiation, thereby temporarily protecting the substrate by grounding to eliminate the static electricity built up during transporkation, etc., and releasing the film from the substrate by treatment with water, warm water, an aqueous acid solution or an aqueous alkali solution as early as possible after the completion of the step of chamfering a grounded circuit part or the step of transportation. CONSTITUTION:A film made from a resin composition essentially consisting of a specified polyoxyalkylene (meth)acrylate monomer and a specified polyfunctional silicone (meth)acrylate is formed on the surface of a liquid crystal substrate subjected to the step of circuit formation and the step of chamfering a grounded part and is cured by irradiation. After the antistatic treatment has been accomplished, the film is released from the substrate by treatment with water, warm water, an aqueous acid solution or an aqueous alkali solution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antistatic method for a liquid crystal substrate, particularly a TFT type liquid crystal substrate having an active element therein.

[0002]

2. Description of the Related Art Active elements mounted on a liquid crystal substrate are prone to electrostatic breakdown. In particular, the generation of static electricity during transportation is fatal to the active element because it is not grounded because the chamfering process of the ground circuit section is completed. As a method for preventing the electrification of such a substrate, a self-discharge type or AC power source type static eliminator is generally used, and a blower type static eliminator for sending ions generated by the static eliminator by a wind is used in order to neutralize both sides. Is effective. However, for example, in the case of a self-discharge type static eliminator, since it is a principle that discharge is caused by the charge generated by the charged body and the charge is neutralized, the effect is not exhibited if the charged level of the charged body is too low. In addition, since the AC type uses AC corona discharge, it has a relatively high capacity and can handle both positive and negative charging polarities, but since the discharge characteristics are not the same in positive and negative, the positive and negative ions generated every half cycle are When applied to an uncharged film that is unequal in number, it will charge to either polarity at a low level. Further, in the case of the blower type static eliminator, there is a problem in the static erasing ability because the number of ions is reduced during the blowing. Other methods include discharging static electricity into the air by increasing the environmental humidity, ionizing or oxidizing the surface where static electricity is generated by chemical treatment, and adding conductivity by adding an antistatic agent. The addition of an antistatic agent was the most common because of its superiority and certainty of effect. As a material for electrical conductivity using such an antistatic agent, (1) metal, (2) metal oxide,
Known are (3) carbon and (4) surfactants.

[0003]

By the way, when metal or carbon is used, the purpose is often electromagnetic wave shielding rather than antistatic. In addition, in the method of adding a surfactant, it is generally added in a large amount in order to play a role as an antistatic agent.
(Transparency) may be impaired. Even when the structure is such that the basic properties are not impaired, it is difficult to remove the antistatic component in the crosslinked portion after achieving the role of antistatic.

The present invention has been made in view of the above point, and is a resin composition having an antistatic function, which temporarily protects a substrate by grounding static electricity generated during transportation after irradiation of radiation by grounding it. Immediately after finishing the process such as cutting the end face of the circuit part and transportation, water, warm water, acidic aqueous solution,
Another object of the present invention is to provide a temporary antistatic method for a liquid crystal substrate which is peeled off with an alkaline aqueous solution.

[0005]

According to the method of preventing static charge of a liquid crystal substrate of the present invention, the following (a), (b) and (c) are applied to the surface of the liquid crystal substrate on which the circuit formation and the chamfering process of the ground portion are completed. After forming a film made of a resin composition as an essential component, irradiating radiation to cure the film, and after achieving the purpose of antistatic, peel the film with water, warm water, acidic aqueous solution, or alkaline aqueous solution. Is characterized by. (A) 100 parts by weight of a polyoxyalkylene (meth) acrylate oligomer having an unsaturated double bond in the molecule, a weight average molecular weight of 100 to 50,000, and an alkylene addition mole number of 5 or more; ) 1 to 300 parts by weight of a polyfunctional oxyalkylene (meth) acrylate monomer having two or more unsaturated double bonds per molecule, (c) one silyl group and one unsaturated double bond in the molecule. 1 to 300 parts by weight of monofunctional or polyfunctional silicone (meth) acrylate having the above combination.

The present invention will be described in detail below. The polyoxyalkylene (meth) acrylate oligomer used in the present invention is usually obtained by a condensation polymerization method. Examples of these polyoxyalkylene (meth) acrylate oligomers include polyols such as polyoxyethylene diglycol, polyoxyethylene diglycolic acid, polyoxypropylene diglycol and polyoxypropylene diglycolic acid, and polar groups such as polyol acid in the molecule. Polymers having In addition to the condensation polymerization type oligomer, an oligomer obtained by a transesterification reaction of a polyoxyalkylene type oligomer having an unsaturated double bond in the molecule with (meth) acrylic acid or a reaction of (meth) acrylic isocyanate, There are oligomers obtained by the reaction of polyoxyalkylene glycol acid and glycidyl (meth) acrylate, oligomers obtained by the reaction of polyoxyalkylene glycol with epichlorohydrin, and the like. For example, (meth) acrylic acid adduct of polyethylene glycol or polypropylene glycol, (meth) acrylic isocyanate adduct of polyethylene glycol or polypropylene glycol, glycidyl (meth) acrylate adduct of polyethylene glycol acid or polypropylene glycol acid, polyethylene glycol monoglycidyl ether. , (Meth) acrylic acid adducts of polyethylene glycol diglycidyl ether. As the group having an unsaturated double bond to be introduced into the molecule, among the vinyl group, vinyloxy group, acryloyl group, methacryloyl group, etc., the reactivity of the acryloyl group and the methacryloyl group is fast and good results can be obtained. When the molecular weight of such an oligomer is less than 100, the concentration of oxyethylene groups per molecule is reduced, so that the hydrophilicity is reduced and it becomes difficult to peel the oligomer for a short time with water or the like. Further, if the molecular weight is larger than 50,000, the crystallinity due to the repeating structure of oxyethylene is developed and uniform coating becomes difficult. Therefore, the weight average molecular weight is selected within this range, and 200 to 5,000 is selected. Those in the range are more preferable.

Next, as the polyfunctional oxyalkylene (meth) acrylate monomer having two or more unsaturated double bonds in the molecule, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, allyl alcohol diacrylate are used. Acrylate, resorcinol diacrylate, adipic acid diacrylate, phthalic acid diacrylate, polyethylene glycol diacrylate with an addition mole number of 5 or less, trimethylolpropane triacrylate, glycerin triacrylate, pentaerythritol tetraacrylate, sorbitol tetraacrylate, etc. ) Acrylic acid adducts may be mentioned. As in the case of the oligomer, the group having an unsaturated double bond to be introduced into the molecule is preferably a vinyl group, a vinyloxy group, an acryloyl group or a methacryloyl group. Among them, the reactivity of the acryloyl group and the methacryloyl group is particularly fast and good. Results are obtained. As the monofunctional or polyfunctional silicone (meth) acrylate having one or more silyl groups and one or more unsaturated double bonds in the molecule, dimethylolsilane,
2 of trimethylolsilane and tetramethylolsilane
-Hydroxyethyl (meth) acrylate adduct and the like can be used. Also in this case, as in the case of the oligomer or the monomer, a vinyl group, a vinyloxy group, an acryloyl group or a methacryloyl group is effective as the group having an unsaturated double bond to be introduced into the molecule, and the acryloyl group and the methacryloyl group are particularly good. Results are obtained. Two or more unsaturated double bonds are necessary in order to increase the curability and cross-linking degree.

The above-mentioned monofunctional or polyfunctional monomers may be used alone or in combination of two or more if necessary. The resin is a solventless resin whose main component is a relatively low molecular weight oligomer, but from the viewpoint of coating workability,
You can use a small amount of solvent.

The amount of the oligomer, monofunctional or polyfunctional monomer used in the present invention is determined in consideration of the viscosity of the entire resin composition, the adhesion to the liquid crystal substrate, the ease of peeling the resin with water or an aqueous solution, the heat resistance and the like. However, the oligomers exhibiting good properties are such that the blending amount of the monofunctional or polyfunctional monomer is 5 to 300 per 100 parts by weight of the polyoxyalkylene (meth) acrylate oligomer.
It is a part by weight. When the resin of the present invention is cured by ultraviolet rays, at least one of a photoinitiator and a sensitizer is essential, but in addition to that, a diluent, a thickener, a plasticizer, an antioxidant, a filler, a colorant, a conductive agent. You may mix additives, such as a sex imparting agent and a swelling agent. Resin coating thickness is 0.1
in the range of 1 μm to 1 mm, preferably 1 μm to 100 μm
The range is selected.

The radiation dose referred to in the present invention is an absorbed dose of 0.1 to 30 Mrad, more preferably 1 to 10 Mra.
In the case of d and ultraviolet rays, it is used in the range of 0.01 to 30 J / cm2, more preferably 0.05 to 3 J / cm2.
What needs attention during irradiation is the deactivation of active radicals by oxygen. In order to prevent these effects to a minimum, it is necessary to use an inert gas such as nitrogen to obtain an appropriate oxygen concentration or to laminate a plastic film on a resin to shield the oxygen. As an essential component in this case, a photoinitiator such as benzophenone or Michler's ketone, a sensitizer or a derivative thereof is used in an amount of 0.1 per 100 parts of the oligomer.
The initiation reaction can be carried out efficiently by adding -30 parts, preferably 0.5-10 parts.

As the stripping solution for the protective resin irradiated with radiation used in the present invention, water having a water temperature of 0 ° C. or more and 100 ° C. or less, or hot water (hot water) can be used, but from the viewpoint of ease of use and safety,
The water temperature is preferably 20 ° C to 60 ° C. As the stripping liquid other than water, an acid / alkali aqueous solution can be used.
Their concentration can be 0.1% to 90%, but 1
An aqueous solution of 0% or less is more preferable from the viewpoint of safe workability.

The protective resin composition thus obtained has a surface hardness and has an excellent antistatic function.
It is applied to temporary antistatic applications such as liquid crystal substrates, and provides a film that can be quickly peeled off after the purpose of processing and transportation is achieved.

[0013]

The reason why the effect of the present invention is exhibited is not always clear, but it is presumed as follows. That is, the unsaturated double bond between the oligomer and the monofunctional or polyfunctional monomer initiates radical polymerization upon irradiation with radiation, and the number of reaction sites of the monofunctional or polyfunctional monomer is very large, so that a highly crosslinked network structure is formed. Is formed, and this becomes a strong film. On the other hand, since the resin composition forming this film is extremely hydrophilic, it has a small volume specific resistance, and unlike the case of adding an ordinary antistatic agent, the entire film has antistatic ability. become. Next, the mechanism of exfoliation is considered as follows. That is, polymerization shrinkage occurs due to an excessive number of reaction points due to monofunctional or polyfunctional monomers, but at this point the resin is constrained on the liquid crystal substrate and no apparent shrinkage occurs, and the resin has residual stress. here,
It is considered that when water, an acidic or alkaline aqueous solution enters, the hydrophilic resin swells to generate nuclei for cracking, and the swollen antistatic coating easily peels off.

[0014]

EXAMPLES The present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. (Method for producing oligomer 1) 2-hydroxyethyl methacrylate 15 parts, methyl acrylate 9.5 parts, acrylic acid 0.5 part, polyoxyethylene diglycolic acid (ethylene addition mole number 9) 70 parts, β-mercaptopropionic acid 2.5 parts 4,4′-azobis-4-cyanovaleric acid 3 parts were reacted under N _{2 at} 70 ° C. for 5 hours to allow 10 parts glycidyl methacrylate, 0.01 parts hydroquinone, and N, N′-dimethyldodecylamine 0.05. Part is added and the temperature is raised to 85 ° C
At room temperature for 5 hours to obtain a glycidyl methacrylate adduct of polymerized polyethylene glycol acid having an unsaturated double bond at the terminal or side chain. At this time, the ratio of the glycidyl methacrylate adduct of polyethylene glycol acid to the acrylic macromer was about 7: 3.

(Production Method of Oligomer 2) 15 parts of 2-hydroxyethyl acrylate, 5 parts of acrylate, 13 parts of ethyl acrylate, 0.5 part of acrylic acid, polyoxydiethylenediglycolic acid (number of moles of ethylene added is 1).
3) 60 parts, 4 parts of thioglycolic acid, 4 parts of 4,4'-azobis-4-cyanovaleric acid were reacted under N2 at 70 ° C for 5 hours, and then 10 parts of glycidyl methacrylate, 0.01 parts of hydroquinone, N, N'- Dimethyldodecylamine (0.05 part) was added and the reaction was carried out at a temperature of 90 ° C. for 5 hours to obtain a polymer having an unsaturated double bond at the terminal or side chain. At this time, the ratio of the glycidyl methacrylate adduct of polyethylene glycol acid and the acrylic macromer was about 6: 4.

Oligomer 3: Polyoxyethylene diacrylate (molecular weight: about 300) Oligomer 4: Polyoxyethylene diacrylate (molecular weight: about 500) Oligomer 5: Polyoxyethylene diacrylate (molecular weight: about 700) Oligomer 6: Polyoxypropylene diacrylate (Molecular weight about 300) Oligomer 7: Polyoxypropylene diacrylate (Molecular weight about 500) Oligomer 8: Polyoxypropylene diacrylate (Molecular weight about 800) Monomer 1: 1, 6-hexanediol diacrylate Monomer 2: Trimethylolpropane triacrylate Monomer 3: Triethylene glycol dimethacrylate

A predetermined amount of the oligomer and the monomer obtained as described above were mixed and stirred, and the resin was applied to a liquid crystal substrate on which an ITO film was formed by a vapor deposition method and a sputtering method so as to have a thickness of 10 μm. On the liquid crystal substrate coated with these resins, while purging with nitrogen, an atmosphere having an oxygen concentration of 100 ppm or less was prepared, and ultraviolet rays were irradiated by an ultraviolet ray irradiator.
It was irradiated with J / cm 2. Static electricity was forcibly generated on the circuit-formed surface of the liquid crystal substrate with an antistatic film thus produced, and the amount of static electricity generated was measured. After that, the surface was visually inspected, and the state at that time was compared with the initial state.
Further, the liquid crystal substrate with the antistatic film was immersed in water, the peeling time of the film was measured, and the surface condition of the liquid crystal substrate after peeling was observed with an electron microscope to compare with the first one. The pencil hardness and volume resistivity of the film were also measured at the same time. The results are shown in Table 1.

(Measurement of the amount of static electricity) The generation conditions were as follows: cotton gauze was used, a load of 200 g was applied to an area of 4 cm × 5 cm of the glass substrate with a protective film, and a distance of 8.5 cm was repeated 20 times for 30 seconds. The electrostatic voltage immediately after rubbing was measured with an electrostatic voltage measuring device. The condition when measuring is the temperature 24
The temperature was 60 ° C. and the humidity was 60% RH.

[0019]

[Table 1]

[0020]

As is apparent from the examples in the table, the antistatic method for a TFT type liquid crystal substrate or the like according to the present invention has a generated static voltage of 100 V or less and a volume resistivity of 10 ⁸ Ω.
Since it is as small as cm, it is a tough transparent film with excellent antistatic properties. After use, it completely peels off within a few tens of seconds and does not contaminate the ITO surface, making it suitable for antistatic methods for liquid crystal substrates. It is clear that

Front page continued (72) Inventor Yutaka Yamaguchi 1500 Ogawa, Shimodate-shi, Ibaraki Hitachi Chemical Co., Ltd. Shimodate Research Laboratory (72) Inventor Hisao Kawaguchi 22-22 Abenocho, Osaka City Osaka Prefecture Sharp Corporation

Claims (4)

[Claims] 1. A film is formed on the surface of a liquid crystal substrate on which the circuit formation and the chamfering process of the ground portion have been completed, and after achieving the purpose of preventing static electricity, the film is removed with water, warm water, an acidic aqueous solution, or an alkaline aqueous solution. A method for preventing electrification of a liquid crystal substrate, comprising: 2. A film is formed on the surface of a liquid crystal substrate and then the film is cured by irradiation with radiation.
An antistatic method for a liquid crystal substrate as described above. 3. The method for preventing static charge of a liquid crystal substrate according to claim 1, wherein the film formed on the surface of the liquid crystal substrate is a resin composition containing the following (a) and (b) as essential components. (A) 100 parts by weight of a polyoxyalkylene (meth) acrylate oligomer having an unsaturated double bond in the molecule, a weight average molecular weight of 100 to 50,000, and an alkylene addition mole number of 5 or more; ) 1 to 300 parts by weight of a polyfunctional oxyalkylene (meth) acrylate monomer having two or more unsaturated double bonds per molecule in the molecule. 4. The method for preventing static charge of a liquid crystal substrate according to claim 1, wherein the film formed on the surface of the liquid crystal substrate is a resin composition containing the following (a), (b) and (c) as essential components. (A) 100 parts by weight of a polyoxyalkylene (meth) acrylate oligomer having an unsaturated double bond in the molecule, a weight average molecular weight of 100 to 50,000, and an alkylene addition mole number of 5 or more; ) 1 to 300 parts by weight of a polyfunctional oxyalkylene (meth) acrylate monomer having two or more unsaturated double bonds per molecule, (c) one silyl group and one unsaturated double bond in the molecule. 1 to 300 parts by weight of monofunctional or polyfunctional silicone (meth) acrylate having the above combination.