JP3191889B2 - Antistatic method for liquid crystal substrate - Google Patents

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 easily damaged by static electricity. In particular, the generation of static electricity is fatal to the active element because it is not grounded during the edge cutting step or during transportation. In general, a self-discharge type or an AC power type static eliminator is used as an antistatic method for such a substrate, and a blower type static eliminator that sends ions generated by static elimination by wind to remove static electricity on both surfaces is used. Is effective. However, for example, in the case of a self-discharge type static eliminator, discharge is caused by the charge generated by the charged body, and the charge is neutralized. Therefore, if the charge level of the charged body is too low, the effect is not exhibited. In addition, the AC method uses AC corona discharge, so its ability is relatively high and can handle both positive and negative charging polarities.However, since the discharge characteristics are positive and negative and not the same, the positive and negative ions generated every half cycle When applied to an unequal number of uncharged films, the charge will be of either polarity, albeit at a lower level. In the case of a blower type static eliminator, there is a problem in static elimination ability because ions are reduced in the middle of blowing. Other methods include discharging static electricity into the air by increasing the environmental humidity, ionizing or oxidizing the surface on which static electricity is generated by chemical treatment, and adding conductivity to the surface by adding an antistatic agent. The addition of an antistatic agent was most common because of its superiority in terms of surface and certainty of the effect.

[0003] Examples of such conductive materials using an antistatic agent include (1) metal, (2) metal oxide, (3) carbon, and (4) surfactant. When metal or carbon is used, the purpose is often to shield electromagnetic waves rather than to prevent static electricity. In addition, in the method of adding a surfactant, it is generally added in a large amount to play a role as an antistatic agent, and may impair the basic characteristics (mechanical and transparency) of the base resin. Even in the case of a structure that does not impair basic characteristics, it is difficult to remove the antistatic component in the crosslinked portion after achieving the role of antistatic. Further, in the type in which an antistatic film is formed and the film is peeled off after achieving the object, there is a problem that static electricity is easily generated newly.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and is directed to forming a film made of a resin composition having an antistatic function on the surface of a liquid crystal substrate, and thereafter cutting the end surface of the ground circuit portion. Temporarily protects the substrate from static electricity generated at the time, and provides a temporary antistatic method for the liquid crystal substrate, which is quickly peeled off with water, warm water, acidic aqueous solution, or alkaline aqueous solution after the process such as cutting and transporting the end surface of the earth circuit part It is something you want to do.

[0005]

Antistatic method for a liquid crystal substrate according to the present invention SUMMARY OF THE INVENTION may, on the surface of the liquid crystal substrate, having an unsaturated double bond in the (a) molecule, a weight average molecular weight
Is in the range of 100 to 50,000,
Glycol of polyoxyalkylene glycolic acid having a number of 5 or more
100 parts by weight of sidyl (meth) acrylate and (b) two or more unsaturated double bonds per molecule
Having polyfunctional oxyalkylene (meth) acrylate
After forming a cured film of a resin composition containing 1 to 300 parts by weight of the nomer as an essential component and achieving the purpose of antistatic, the film is peeled off with water, hot water, an acidic aqueous solution, or an alkaline aqueous solution. I do.

Hereinafter, the present invention will be described in detail. The polyoxyalkylene (meth) acrylate oligomer used in the present invention is usually obtained by a condensation polymerization method. 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 acids in the molecule. A polymer having the following formula:

The polyoxyalkylene glycol according to the present invention
When the molecular weight of glycidyl (meth) acrylate of cholic acid is smaller than 100, the concentration of oxyethylene groups per molecule decreases, so that the hydrophilicity decreases, and it becomes difficult to remove the glycidyl (meth) acrylate with water for a short time. On the other hand, if the molecular weight is larger than 50,000, crystallinity due to the repeating structure of the oxyalkylene is developed and uniform coating becomes difficult.
Those in the range of 5,000 are more preferred.

Next, polyfunctional oxyalkylene (meth) acrylate monomers having two or more unsaturated double bonds in the molecule include 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, and allyl alcohol diacrylate. Acrylates, resorcinol diacrylates, adipic diacrylates, phthalic diacrylates, polyethylene glycol diacrylates having an added mole number of 5 or less, trimethylolpropane triacrylate, glycerin triacrylate, pentaerythritol tetraacrylate, sorbitol tetraacrylate, etc. ) Acrylic acid adducts. The group having an unsaturated double bond introduced into the molecule is, similarly to the case of the oligomer, a vinyl group, a vinyloxy group, an acryloyl group, and a methacryloyl group, and among them, particularly, the reactivity of the acryloyl group and the methacryloyl group is fast and good. Results are obtained. Monofunctional or polyfunctional silicone (meth) acrylates having one or more silyl groups and one or more unsaturated double bonds in the molecule include dimethylolsilane,
Trimethylolsilane and tetramethylolsilane 2
-Hydroxyethyl (meth) acrylate adduct can be used. In this case, as in the case of the oligomer or the monomer, as the group having an unsaturated double bond to be introduced into the molecule, a vinyl group, a vinyloxy group, an acryloyl group, and a methacryloyl group are effective, and an acryloyl group and a methacryloyl group are particularly good. Results are obtained. One or more unsaturated double bonds are required per molecule in order to increase curability and increase the degree of crosslinking.

The above polyfunctional oxyalkylene (meth)
Acrylate monomer is used as an essential component,
Monofunctional or polyfunctional silicone (meth) acrylates
Used as needed. Although the resin is a solventless resin containing a relatively low molecular weight oligomer as a main component, a small amount of a solvent may be used from the viewpoint of coating workability.

The aforementioned oligomer, ie, polyoxy
Glycidyl (meth) acryle of alkylene glycolic acid
Against over 100 parts by weight, the amount of mono- or polyfunctional monomer, 5 to 300 parts by weight, respectively is preferred. When curing the resin composition of the present invention by ultraviolet light, at least one photoinitiator or sensitizer is essential, other diluents, thickeners, plasticizers, antioxidants, fillers,
Additives such as a coloring agent, a conductivity-imparting material, and a swelling agent may be blended. The coating thickness of the resin composition is 0.1 μm to 1 mm
And preferably in the range of 1 μm to 100 μm.

The radiation dose referred to in the present invention is 0.1 to 30 Mrad, more preferably 1 to 10 Mrad in terms of absorbed dose.
d, are used in a range of cases 0.01~30J / cm ² of ultraviolet preferred over 0.05~3J / cm ^2. Attention should be paid to the irradiation in which the active radical is deactivated by oxygen. In order to minimize these effects, it is necessary to shield the oxygen with an appropriate oxygen concentration using an inert gas such as nitrogen or by laminating a plastic film on a resin. At this time, a photoinitiator such as benzophenone or Michler's ketone, a sensitizer or a derivative thereof is used as an essential component in an amount of 0.1 to 30 parts per 100 parts of the oligomer.
Parts, preferably 0.5 to 10 parts,
The initiation reaction can be performed efficiently.

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

The antistatic resin composition thus obtained has a surface hardness and an excellent antistatic function.
It is applied to temporary antistatic applications such as FT-type liquid crystal substrates, and provides a film that can be quickly peeled off after achieving the purpose of cutting or transporting the end face of the ground part.

[0014]

The reason why the effects of the present invention are realized is not necessarily clear, but is presumed as follows. That is, the unsaturated double bond of the oligomer, monomer and monofunctional or polyfunctional silicone starts radical polymerization by irradiation,
Further, since the reaction points of the monomer and the monofunctional or polyfunctional silicone are very large, a highly crosslinked network structure is formed, which becomes a tough film. On the other hand, since the resin composition forming this film has a very strong hydrophilicity,
The volume specific resistivity is small, and unlike the case where a normal antistatic agent is added, the entire film has an antistatic function. Next, the mechanism of occurrence of peeling is considered as follows. That is, polymerization shrinkage occurs due to excessive reaction points due to monomer and monofunctional or polyfunctional silicone, but at this time, the resin is restrained on the liquid crystal substrate and apparent shrinkage does not occur,
It will have residual stress. Here, it is considered that when water, an acidic or alkaline aqueous solution enters, the hydrophilic resin swells, nuclei of cracks are generated, and the swollen antistatic film easily peels off. In addition, in this peeling step, since the film is peeled off in a state of being immersed in water, there is no stagnation of static electricity, so that it is considered that the film has a very excellent antistatic function.

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. (Production method of oligomer 1) 2-hydroxyethyl methacrylate 15 parts, methyl acrylate 9.5 parts, acrylic acid 0.5 parts, polyoxyethylene diglycolic acid (ethylene addition mole number 9) 70 parts, β-mercaptopropionic acid 2.5 parts of 4,4′-azobis-4-cyanovaleric acid was reacted at 70 ° C. for 5 hours under N 2 for 5 hours, 10 parts of glycidyl methacrylate, 0.01 part of hydroquinone, N, N ′
-Dimethyl dodecylamine (0.05 part) was added, and the temperature was raised to 85.
C. 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 glycolic acid to the acrylic macromer was approximately 7: 3.

(Production Method of Oligomer 2) 15 parts of 2-hydroxyethyl acrylate, 5 parts of acrylamide, 13 parts of ethyl acrylate, 0.5 part of acrylic acid, polyoxydiethylene diglycolic acid (1 mole of ethylene added)
3) After reacting 60 parts, 4 parts of thioglycolic acid, 3 parts of 4,4'-azobis-4-cyanovaleric acid at 70 ° C for 5 hours under N2, 10 parts of glycidyl methacrylate, 0.01 part of hydroquinone, N, N'- After adding 0.05 part of dimethyldodecylamine, the mixture was reacted at a temperature rise of 90 ° C. for 5 hours to obtain a polymer having an unsaturated double bond at a terminal or a side chain. At this time, the ratio of the glycidyl methacrylate adduct of polyethylene glycol acid to the acrylic macromer was approximately 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 resin obtained by mixing and stirring a predetermined amount of the oligomer and monomer obtained as described above 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 a liquid crystal substrate coated with these resins, an atmosphere having an oxygen concentration of 100 ppm or less was applied while purging with nitrogen, and ultraviolet rays were irradiated with an ultraviolet irradiation device for 1 hour.
J / cm ^{2 was} irradiated. The ground portion of the thus prepared liquid crystal substrate with an antistatic film was cut at the end face, and the amount of generated static electricity was measured. Thereafter, the surface was visually observed, and the state at that time was compared with the initial state. Further, the liquid crystal substrate provided with the antistatic film was immersed in water, the peeling time of the film was measured, and the surface state of the liquid crystal substrate after peeling was observed with an electron microscope and compared with the first one. The measurements of the pencil hardness and the volume resistivity of the film were also performed at the same time. Table 1 shows the results.

[0019]

[Table 1]

[0020]

As is clear from the embodiments shown in the table, the method for preventing electrification of a TFT type liquid crystal substrate or the like according to the present invention has a static voltage generated at the time of cutting the end face of the ground portion of 50 to 100.
V, the volume resistivity is as small as 108 Ω · cm, so that it becomes a tough transparent film with excellent antistatic properties. After use, it is completely peeled off with water within tens of seconds.
Since it does not contaminate the O surface, it is clear that it is suitable for a method for preventing charging of a liquid crystal substrate.

Continued on the front page (72) Inventor: Yutaka Yamaguchi 1500, Oji, Shimodate, Ibaraki Pref.Hitachi Chemical Industry Co., Ltd. (56) References JP-A-60-202158 (JP, A) JP-A-60-42469 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 5/20

Claims (1)

(57) [Claims] To 1. A liquid crystal substrate surface, it has an unsaturated double bond in the (a) molecule, a weight average molecular weight
Is in the range of 100 to 50,000,
Glycol of polyoxyalkylene glycolic acid having a number of 5 or more
100 parts by weight of sidyl (meth) acrylate and (b) two or more unsaturated double bonds per molecule
Having polyfunctional oxyalkylene (meth) acrylate
After forming a cured film of a resin composition containing 1 to 300 parts by weight of the nomer as an essential component and achieving the purpose of antistatic, the film is peeled off with water, hot water, an acidic aqueous solution, or an alkaline aqueous solution. Liquid crystal substrate antistatic method.