JPH07281163A - Anti-static method of liquid crystal substrate - Google Patents

Abstract

PURPOSE:To prevent the breakdown of an active element caused by static electricity by removing static electricity generated at the time of transporting an active element mounted liquid crystal substrate completed in a chamfering process of an earth circuit part. CONSTITUTION:The liquid crystal substrate on which a connection terminal is formed and having an active element is placed on a conductive film and a tape having antistatic property, pressure sensitive adhesiveness and water swelling property is allowed to contact with and stuck to at least the conductive film and the connection terminal of the liquid crystal substrate and is stripped off with water, a hot water, acidic aq. solution and an alkaline aq. solution after used.

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 An active element mounted on a liquid crystal substrate is prone to electrostatic breakdown because it causes logic inversion at a static voltage exceeding a threshold voltage. In particular, the static electricity generated during transportation is the chamfering process of the ground circuit part (when manufacturing the liquid crystal substrate, the ground circuit part and other connection terminals are connected,
Since the process of removing the connecting portion) is completed, it is not grounded, which is fatal to the active element.

In general, as a method of preventing the electrification of such a substrate, a self-discharge type or AC power source type static eliminator is used, and in order to eliminate static electricity on both sides, a blower type static eliminator which sends ions generated by static elimination by wind. It is effective to use such as.
However, for example, in the case of a self-discharge type static eliminator, discharge is caused by the charge generated by the charged body to neutralize the charge, so that the effect is not exhibited if the charge level of the charged body is too low. Since the AC type static eliminator 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 for positive and negative, the positive and negative generated every half cycle. When applied to an uncharged film with unequal numbers of ions, it will be charged 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. Moreover, even though these static elimination methods are effective during the manufacturing process of the liquid crystal substrate and during storage, it is costly to move and transport.
There is a drawback that the effort becomes enormous.

Effective measures against static electricity during movement and transportation include a method of discharging static electricity into the air by increasing environmental humidity, a method of ionizing or oxidizing the surface where static electricity is generated by chemical treatment, and addition of an antistatic agent. However, the addition of an antistatic agent is the most common method because of its superiority in terms of cost and certain effect. As materials for making conductive using such an antistatic agent, (i) metal, (ii) metal oxide, (iii) carbon,
(Iv) There are surfactants and the like. When a metal or carbon is used, the purpose is to shield electromagnetic waves rather than to prevent static electricity, and since a large amount of conductive particles are usually added at that time, the basic properties of the base resin, such as adhesiveness, are often impaired.
On the other hand, in the method of adding the surfactant, since it plays a role as an antistatic agent, it is added in a large amount like the conductive particles.
After all, the basic properties (mechanical and transparency) of the base resin were often impaired. In any case, even if a configuration that does not impair the basic characteristics is possible,
After achieving the role of antistatic, it has a drawback that it is difficult to remove the antistatic component in the crosslinked portion.

On the other hand, a method using a peelable resin which swells with water is disclosed in JP-A-5-4442 and JP-A-5-4443. At this time, a resin that has entered a minute gap of a liquid crystal substrate. However, there is a problem that the residue is not peeled off with water and is likely to remain, so that the residue adversely affects the electrical characteristics when the drive circuit is connected. Further, even if an attempt is made to achieve this object by using a commercially available antistatic tape or the like, there is a drawback that the active element is destroyed due to a small amount of static electricity generated when the tape is peeled off.

[0006]

DISCLOSURE OF THE INVENTION The present invention has been made as a result of earnest studies in view of the above problems, and eliminates static electricity generated at the time of transportation of an active element-equipped liquid crystal substrate whose chamfering process of a ground circuit section has been completed, It is an object of the present invention to provide a simple method for preventing breakdown of an active element due to static electricity.

[0007]

That is, according to the present invention, a liquid crystal substrate having a connection terminal formed on a conductive film is placed, and at least the connection terminal of the conductive film and the connection terminal of the liquid crystal substrate is brought into contact with the substrate to charge. Prevention, pressure-sensitive adhesiveness
The present invention relates to a method for preventing electrification of a liquid crystal substrate, which comprises applying a water-swelling tape, and after achieving a predetermined purpose, peeling the tape with water, warm water, an acidic aqueous solution or an alkaline aqueous solution. The present invention will be described in detail below.

The antistatic property of the tape of the present invention having antistatic property, pressure-sensitive adhesive property and water swelling property means that the surface resistivity is 108.
Ω · cm or less. Pressure-sensitive adhesiveness means that it has tackiness at room temperature and its adhesive force is 10gf / cm (peeling speed 50mm / c
m) The above. Water swellability means that the water vapor permeability is 100 g /
m2 · 24h · 40 ℃ or higher. Examples of the constituent materials that satisfy these requirements are as follows.

(I) Tape base material Polyvinyl alcohol, cellophane, nylon, EV
A, EVOH (ethylene-vinyl alcohol copolymer,
Water-swellable base materials such as ethylene-vinyl acetate copolymer) or paper are suitable, and those having a thickness of 10 to 200 μm can be used, but those having a thickness of 20 to 100 μm are more suitable.

(Ii) Main component of adhesive A hydrophilic prepolymer having an unsaturated double bond in the molecule is preferable, and a polyoxyalkylene type polymer is subjected to a transesterification reaction with (meth) acrylic acid or (meth) acrylic isocyanate. The polymer obtained by the reaction with, the polymer obtained by the reaction between polyoxyalkylene glycol acid and glycidyl (meth) acrylate, and the polymer obtained by the reaction between polyoxyalkylene glycol and epichlorohydrin are used. 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. Acryloyl group and methacryloyl group have good reactivity as a group to be introduced in the molecule, and good results are obtained.

(Iii) Additive In the present invention, better results can be obtained by incorporating a hydrophilic monomer having a functional group in addition to the above hydrophilic polymer. Examples of such a monomer include epoxy acrylate, urethane acrylate, polyether acrylate and polyester acrylate. Especially from the viewpoint of the adhesiveness of the film and the ease of peeling with water,
Epoxy acrylate and polyether acrylate are excellent. As the epoxy acrylate, 1,6-hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, allyl alcohol diglycidyl ether, resorcinol diglycidyl ether, adipic acid diglycidyl ester, phthalic acid diglycidyl ester, the number of addition moles is (Meth) acrylic acid adducts of polyethylene glycol diglycidyl ether of 5 or less, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether, sorbitol tetraglycidyl ether and the like can be mentioned.

When the chain transfer agent is used in the present invention, a thiol compound having at least two or more mercapto groups in one molecule is necessary. For example, trimethylolpropane tris (β-thiopropionate), trialkyl Methylolpropane triso (thioglycolate), pentaerythritol tetrakisoo (thioglycolate) and the like are effective. These chain transfer agents are added to disperse the crosslinks during radiation curing, but the addition amount is 0.5 to 50 parts by weight with respect to 100 parts by weight of the hydrophilic prepolymer,
It is preferable to select in the range of 1 to 30 parts.

Next, the acrylic polymer having a functional group will be described. As the monomer constituting the polymer, in addition to (meth) acrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate and butyl (meth) acrylate, acrylic acid, itaconic acid, hydroxyethyl (meth) acrylate, Examples include hydrophilic functional group-containing monomers such as ethoxyethyl acrylate, (meth) acrylamide, diacetonoacrylamide, N-methylol (meth) acrylamide, dimethylaminoethyl (meth) acrylate, and N-vinylpyridone. The weight average molecular weight of the polymer can be adjusted by adjusting the concentration of the initiator and the concentration of the chain transfer agent such as a mercapto compound, and a polymer having a weight average molecular weight of 500 to 50,000 is selected. If necessary, the resin used in the present invention may contain additives such as a photoinitiator, a sensitizer, a diluent, a plasticizer, an antioxidant, a filler and a swelling agent.

(Iv) Blending of Adhesive / Coating on Tape Base Material Polyoxyalkylene type polymer which is a hydrophilic polymer
1 to 300 parts by weight of acrylic monomer for 100 parts by weight,
The best tape characteristics can be obtained when 5 to 50 parts by weight of an acrylic polymer is used in combination. The thickness of the adhesive layer is in the range of 0.1 to 100 μm, but 1 to 30 μm is preferable from the viewpoints of heat resistance, handleability, cost, etc., and it is applied to the above-mentioned tape base material and dried if necessary. Be used for the process.

(V) Curing method of adhesive When the radiation curing method is used in the present invention, α ray, β ray, γ ray
Active energy rays such as X-rays, neutron rays, X-rays, accelerated electron rays, and ultraviolet rays can be used. The irradiation dose is usually 0.1 to 100 Mrad for electron beams, but 1 to 2
0Mrad is desirable. 0.01 to 10 J / cm2 for ultraviolet rays
0.1 to 3 J / cm @ 2 is particularly suitable. What needs attention during irradiation is the deactivation of active radicals by oxygen. In order to prevent this, it is necessary to use an inert gas such as nitrogen to obtain an appropriate oxygen concentration.

(Vi) Conductive Film Examples of the conductive film used in the present invention include a metal vapor deposition film and a metal foil-plastic two-layer film. P as a plastic substrate for vapor-deposited films
VA (polyvinyl alcohol), nylon, cellophane, EVA, EVOH (ethylene-vinyl alcohol copolymer, ethylene-vinyl acetate copolymer) and the like can be used. In the case of vapor-deposited metal films, aluminum, copper or the like can be made electrically conductive by vacuum-depositing aluminum, copper or the like on these plastic films, if necessary, in the range of 10 to 10,000 angstroms. Also, as the metal foil for the 2 (multi-layer) film, aluminum, copper, gold, silver, etc. 0.1 μm
It is possible to use a material having a size of at least m and less than 100 μm, and to make it conductive by attaching them with an appropriate adhesive.
A (multi) layer film can be obtained.

(Vii) The method of protecting the liquid crystal substrate according to the present invention is as follows. (A) The bottom surface of the liquid crystal substrate is overlaid on the metal vapor deposition (or metal foil) surface of the conductive film that is cut out larger than the surface area of the liquid crystal substrate, and the tape produced by the present invention is cut off larger than the surface area of the liquid crystal substrate, The adhesive surface is attached to the surface of the liquid crystal substrate including the connection terminals. The tape protruding from the liquid crystal substrate is bonded to the conductive film on the opposite surface, which also protrudes from the liquid crystal substrate (FIG. 1). (B) The tape produced by the present invention is cut into a larger amount than the surface area of the liquid crystal substrate, the adhesive surface is attached to the surface of the liquid crystal substrate, and the metal vapor deposition of the conductive film (or the larger amount than the surface area of the liquid crystal substrate) (or Attach the (metal foil) surface to the bottom surface including the connection terminals of the liquid crystal substrate. The conductive film protruding from the liquid crystal substrate is bonded to the tape on the opposite surface, which also protrudes from the liquid crystal substrate (FIG. 2). Also, by the method (a), the tape is cut into a suitable size,
It may be attached only to a part such as a terminal portion of the liquid crystal substrate.

(Viii) Peeling method of tape The antistatic tape produced through these steps is used for antistatic purposes for liquid crystal substrates, and after use, sprayed or soaked with water, warm water, acidic aqueous solution, alkaline aqueous solution. As a result, the liquid crystal substrate is quickly separated and removed.

[Action] The reason why the effect of the present invention is exhibited is not always clear, but it is presumed as follows. (I) Reason why this composition develops antistatic properties for the liquid crystal substrate The most effective antistatic method for the liquid crystal substrate is to ground the chamfering process section. In the liquid crystal substrate protection method of this configuration, the terminal portion after the chamfering process is protected by the tape having the antistatic function, and even if a minute charge is generated on the tape, it flows on the conductive film on the opposite surface. Therefore, it is considered that the effect is great. (Ii) The composition is treated with water, an acidic aqueous solution, an alkaline aqueous solution,
Or the reason why the tape peels well from the liquid crystal substrate when the organic solvent is binary. Unsaturation in hydrophilic prepolymer and polyfunctional monomer 2
The heavy bonds undergo a radical chain reaction to form a highly crosslinked network structure. Polymerization shrinkage occurs because there are so many reaction points of the polyfunctional monomer, but apparent shrinkage does not occur while the resin is constrained on the base material, resulting in residual stress. Water and the like will infiltrate from above this hydrophilic substrate film,
It is considered that the residual stress is released due to the swelling of the film and the resin, and the tape easily peels off from the glass surface of the liquid crystal substrate. Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

[0020]

【Example】

<Hydrophilic prepolymer 1> Polypropylene glycol dimethacrylate (Mw = 13,000) <Hydrophilic prepolymer 2> Polyethylene glycol diacrylate (Mw = 800) <Acrylic polymer 1> 40 parts butyl methacrylate, 50 parts ethyl acrylate, acrylic After reacting 10 parts of acid, 2.5 parts of β-mercaptopropionic acid, and 3 parts of 4,4′-azobis-4-cyanovaleric acid under N 2 at 70 ° C. for 5 hours, 0.01 part of hydroquinone was added to obtain an acrylic polymer. Mw about 50
10,000%, NV = 10% <Acrylic polymer 2> 80 parts of butyl methacrylate, 12.5 parts of acrylonitrile, 7.5 parts of acrylic acid, 2.5 parts of β-mercaptopropionic acid, 3 parts of 4,4′-azobis-4-cyanovaleric acid and 70 parts of N2 under 70%. After reacting at 5 ° C for 5 hours, 0.01 part of hydroquinone was added to obtain an acrylic polymer. Mw about 15
10,000, NV = 20% <Chain transfer agent 1> Trimethylolpropane triso (β
-Thiopropionate) <Chain transfer agent 2> Pentaerythritol tetrakis (thioglycolate)

The hydrophilic prepolymer and acrylic polymer obtained as described above were mixed with a polyfunctional chain transfer agent and a thermal crosslinking agent (polyisocyanate) in predetermined amounts and stirred. This resin composition was applied onto a PVA or cellophane film having a thickness of 30 to 40 μm so that the coating thickness after drying would be 25 μm, and heated at 90 ° C. for 20 minutes. The resulting composition is (a) irradiated with a certain dose of ultraviolet rays in the air (b) while purging with nitrogen gas so that the oxygen concentration is 500 ppm or less, and an accelerating voltage of 175 KV is applied to a predetermined amount with an electron beam irradiation device. It was irradiated with an electron beam. By the method described above on the liquid crystal substrate after the chamfering process,
This tape was sandwiched between 500 angstrom aluminum vapor-deposited films, and a predetermined amount of static electricity was forcibly applied by a static electricity generator to measure the electrostatic withstand voltage of the antistatic tape. After measurement, dip the tape in distilled water and peel it from the substrate,
The surface condition of the liquid crystal substrate was observed.

Example 1 Hydrophilic prepolymer 1 100 parts Acrylic polymer 1 20 parts Chain transfer agent 1 5 parts Substrate PVA 30 μm Electron beam irradiation dose 5 Mrad

Example 2 Hydrophilic prepolymer 1 100 parts Acrylic polymer 1 20 parts Chain transfer agent 1 5 parts Coronate L (trifunctional isocyanate) 2.5 parts Substrate PVA 30 μm Electron beam irradiation dose 5 Mrad

Example 3 Hydrophilic Prepolymer 1 100 parts Acrylic Polymer 1 10 parts Chain Transfer Agent 1 2.5 parts Substrate PVA 40 μm Electron Beam Irradiation Dose 10 Mrad

Example 4 Hydrophilic prepolymer 2 100 parts Acrylic polymer 1 40 parts Chain transfer agent 1 10 parts Coronate L (trifunctional isocyanate) 2 parts Substrate PVA 30 μm Electron beam irradiation dose 5 Mrad

Example 5 Hydrophilic Prepolymer 2 100 parts Acrylic polymer 2 15 parts Chain transfer agent 2 15 parts Substrate PVA 30 μm Electron beam irradiation dose 5 Mrad

Example 6 Hydrophilic Prepolymer 1 100 parts Acrylic Polymer 1 20 parts Chain Transfer Agent 1 5 parts Substrate PVA 30 μm Electron beam irradiation dose 20 Mrad

Example 7 Hydrophilic Prepolymer 1 100 parts Acrylic Polymer 1 20 parts Chain Transfer Agent 1 5 parts Substrate Cellophane 30 μm Electron beam irradiation dose 5 Mrad

Example 8 Hydrophilic Prepolymer 1 100 parts Acrylic Polymer 1 20 parts Chain Transfer Agent 1 5 parts Base material Cellophane 30 μm Ultraviolet irradiation dose 1.0 J / cm 2

Comparative Example 1 Hydrophilic Prepolymer 1 100 parts Acrylic Polymer None Chain Transfer Agent 1 5 parts Substrate PVA 30 μm electron beam irradiation dose 5 Mrad Comparative Example 2 Hydrophilic Prepolymer 1 100 parts Acrylic Polymer 1 20 parts Chain Transfer Agent None Group Material Cellophane 30 μm Electron beam irradiation dose 5 Mrad

Comparative Example 3 Hydrophilic Prepolymer 2 100 parts Acrylic Polymer 1 20 parts Chain Transfer Agent 1 5 parts Base Material Polyethylene Film 40 μm Electron Beam Dose 5 Mrad Comparative Example 4 Hydrophilic Prepolymer 2 100 parts Acrylic Polymer 2 20 parts Chain Transfer agent 2 5 parts Base material Cellophane 30 μm Electron beam irradiation dose 50 Mrad

[0032]

[Table 1] ───────────────────────────────── Withstand voltage (V) Peeling time (min) After peeling Surface state of the liquid crystal substrate of ───────────────────────────────── Example 1 ＞ 3000 1 No abnormality 2 〃 3 〃 3 〃 2 〃 4 〃 3 〃 5 〃 0.5 〃 6 〃 2 〃 7 〃 1 〃 8 〃 1 〃 ──────────────────────── ──────── Comparative Example 1 No adhesion −−2 Unhardened −− 3 800 Not peelable − 4 2000 〃 − ──────────────────── ─────────────

[0033]

As is apparent from the examples, the antistatic method for liquid crystal substrates using the adhesive tape of the present invention has good antistatic properties and adhesive properties, and can be easily peeled off with water after use. It is useful as an antistatic method for a liquid crystal substrate, particularly a TFT type liquid crystal substrate having an active element inside.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the method of the present invention.

FIG. 2 is a sectional view showing another embodiment of the method of the present invention.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshikatsu Mikami 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Inside Hitachi Chemical Co., Ltd.

Claims (1)

[Claims] 1. A liquid crystal substrate having a connection terminal formed on a conductive film is placed and brought into contact with at least the connection terminals of the conductive film and the liquid crystal substrate to provide antistatic property, pressure-sensitive adhesive property, and water. A method for preventing electrification of a liquid crystal substrate, which comprises applying a swelling tape, peeling the tape with water, warm water, an acidic aqueous solution or an alkaline aqueous solution after use.