JPH08288090A - Static charge preventing method for liquid crystal substrate - Google Patents

Abstract

PURPOSE: To provide a static charge preventing method for a liquid crystal substrate, which can effectively prevent the breakdown of an active element due to the static electricity to be generated at the time of transportation, in a liquid crystal substrate loaded with an active element, in which the trimming process of an earth circuit is concluded. CONSTITUTION: A static charge preventing tape 20, a liquid crystal substrate 10 and a conductive film 30 are provided, and at least a circuit terminal part 11 of the liquid crystal substrate 10 is coated with the static charge preventing tape 20, and the static charge preventing tape 20 and the conductive film 30, which is arranged on the bottom surface of the liquid crystal substrate 10, are adhered to each other. With this structure, the terminal part 11 of the liquid crystal substrate 10 can be securely protected from the electrostatic charge, and after the use, the static charge preventing tape 20 can be easily peeled off from the liquid crystal substrate 10 by water, hot water, acid solvent or alkaline solvent.

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 Usually, an active element mounted on a liquid crystal substrate is susceptible to electrostatic breakdown because it causes logic inversion at a static voltage exceeding a threshold voltage. In particular, the generation of static electricity during product transportation is fatal to the active element because it is not grounded because the chamfering process of the ground circuit section is completed.

Generally, a self-discharge type or AC power source type static eliminator is used as a method of preventing static charge on a liquid crystal substrate. Further, in order to neutralize both surfaces, a blower blows ions generated by the static eliminator by wind. It is effective to use a static eliminator.

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 charged level of the charged body is too low.

Further, since the AC power source type static eliminator uses AC corona discharge, it has a relatively high capacity and can cope with both positive and negative charging polarities, but the discharge characteristics are not the same for positive and negative, so every half cycle. When the number of positive and negative ions generated in the film is not equal and it is applied to an uncharged film, the film is charged to either polarity although the level is low.

Further, in the case of a 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 the above-described static elimination method is effective during the manufacturing process and storage of the liquid crystal substrate, there is a problem that the cost and labor required for moving and transporting it become enormous.

Effective countermeasures against static electricity during transportation 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 in terms of cost advantages and certain effects.

[0009]

As materials for making conductive using the above-mentioned antistatic agent, there are (1) metal, (2) metal oxide, (3) carbon, (4) surfactant and the like. When using metal or carbon, 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 adhesion are often impaired. The problem was pointed out.

On the other hand, the method of adding a surfactant serves as an antistatic agent, and therefore, like the conductive particles,
When added in a large amount, the basic properties (mechanical and transparency) of the base resin were often impaired.

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, it enters into a minute gap of a liquid crystal substrate. Since the resin does not peel off with water and remains easily,
There is a problem that the residue adversely affects the electric characteristics when the drive circuit is connected.

Further, even if a commercially available antistatic tape or the like is used to achieve this object, 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.

The present invention has been made in view of the above circumstances, and has been made as a result of years of earnest research by the present inventors. The present invention provides electrostatic discharge of a liquid crystal substrate which is effective during movement and conveyance. As a countermeasure, the basic properties of the base resin are not impaired, an effective antistatic function is achieved, and after use, the protective tape can be easily and easily peeled off from the liquid crystal substrate. Another object of the present invention is to provide a method for preventing static charge of a liquid crystal substrate.

[0014]

In order to achieve the above object, an antistatic method for a liquid crystal substrate according to the present invention provides a conductive film, a liquid crystal substrate, an antistatic property, a pressure sensitive adhesive property and a water swelling property. The circuit of the liquid crystal substrate is constituted by an antistatic tape that has, the circuit terminal portion of the liquid crystal substrate is covered with the antistatic tape, and the antistatic tape is adhered to a conductive film disposed on the bottom surface of the liquid crystal substrate. While protecting the terminal part, after using water, warm water,
The antistatic tape and the conductive film are separated from the liquid crystal substrate by using an acidic aqueous solution, an alkaline aqueous solution or a polar organic solvent.

The antistatic property of the antistatic tape means that the surface resistivity is 10 ¹² Ω or less. Moreover, the pressure-sensitive adhesive property means that it has tackiness at room temperature and its adhesive force is 10 g.
f / cm (peeling speed 50 mm / cm) or more. Also, water swellability means that the water vapor permeability is 100 g / m ² · 2.
4h · 40 ° C or higher. The following materials are suitable as constituent materials that satisfy these requirements.

First, as the tape base material, PVA (polyvinyl alcohol), cellophane, nylon, EVA
A water-swellable base material such as (ethylene-vinyl acetate copolymer), EVOH (ethylene-vinyl alcohol copolymer) or paper is suitable, and those having a thickness of 10 to 200 μm can be used, but a thickness of 20 to 100 μm. Are more suitable.

Next, an acrylic polymer is suitable as the main component of the adhesive applied to the tape substrate, and the monomers constituting this acrylic polymer include methyl (meth) acrylate, ethyl (meth) acrylate,
In addition to (meth) acrylic acid esters such as butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate, acrylic acid, itaconic acid, hydroxylethyl (meth) acrylate, ethoxoethyl acrylate,
(Meth) acrylamide, diacetonoacrylamide,
Examples include hydrophilic functional group-containing monomers such as N-methylol (meth) acrylamide, dimethylaminoethyl (meth) acrylate, and N-vinylpyridone.

As an essential component, the copolymer composition of acrylic acid ester constituting the main component of the skeleton of the acrylic polymer is
A composition in the range of 10 to 60 parts by weight of ethyl acrylate and 90 to 40 parts by weight of butyl acrylate is more preferable.

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 the one having a weight average molecular weight of 50,000 or more is selected.

On the other hand, as a curing agent, an isocyanate compound having at least two isocyanate groups in one molecule is effective, and aromatic compounds such as tolylene diisocyanate and trimethylol propane tris- (tolylene diisocyanate) are effective. Aliphatic isocyanates such as group isocyanate, hexamethylene diisocyanate, trimethylhexamethylene didiisocyanate can be used.

The resin used in the present invention may optionally contain additives such as tackifier, diluent, plasticizer, antioxidant, filler and swelling agent.

Next, the composition of the adhesive and the application of the adhesive to the tape base material are good when 0.1 to 10 parts by weight of the trifunctional isocyanate is added to 100 parts by weight of the acrylic polymer. However, the best tape characteristics are obtained in the range of 1 to 5 parts by weight.

When the amount of both of the trifunctional isocyanates is 10 parts by weight or more, the adhesive strength is decreased due to excessive crosslinking, and
If it is less than 1 part by weight, cohesive failure of the adhesive occurs due to insufficient crosslinking. The thickness of the adhesive layer is in the range of 0.1 to 100 μm, but is preferably 1 to 30 μm from the viewpoint of heat resistance, ease of handling, cost, etc., and is applied to the above-mentioned tape base material, if necessary. And then subjected to the drying process.

Next, as a conductive film used in the present invention, a metal vapor deposition film and a metal foil-plastic are used.
A (multi) layer film may be mentioned. PE (polyethylene), PP (polypropylene), PET (polyethylene terephthalate), etc. can be used as a plastic base material of a vapor deposition film. In the case of a vapor-deposited metal film, aluminum, copper or the like can be made to be conductive by vacuum-depositing 0.001 to 1.0 μm on these plastic films, if necessary. Further, as the metal foil for the two (multi) layer film, aluminum, copper,
It is possible to use gold, silver, or the like having a thickness of 0.1 μm or more and 100 μm or less, and by bonding these with an appropriate adhesive or the like, a conductive two (multi) layer film can be obtained.

Further, regarding the peeling method of the antistatic tape, the antistatic tape prepared through the above steps is used for the antistatic use of the liquid crystal substrate, and then water, warm water, acidic aqueous solution, alkaline aqueous solution, methanol, etc. By spraying or immersing the entire surface with the polar organic solvent, the film is promptly removed from the liquid crystal substrate.

[0026]

The action of the method of the present invention is presumed as follows.

First, the reason why the method of the present invention develops the antistatic property of the liquid crystal substrate is that the most effective antistatic method for the liquid crystal substrate is to ground the chamfering process part, but the liquid crystal substrate protection of this construction is performed. In the method, the terminal part that has finished the chamfering process is protected by an antistatic tape having an antistatic function, and even if a minute charge is generated on the antistatic tape, it flows on the conductive film on the opposite surface. , The effect is considered to be great.

The reason why the antistatic tape peels well from the liquid crystal substrate when immersed in water, an acidic aqueous solution, an alkaline aqueous solution or an organic solvent is that the unsaturated double bond in the hydrophilic prepolymer and the polyfunctional monomer is used. Undergo a radical chain reaction to form a highly crosslinked network structure. Since the polyfunctional monomer has a large number of reaction points, polymerization shrinkage occurs, but apparent shrinkage does not occur while the adhesive is constrained on the tape base material, resulting in residual stress.

It is considered that since water or the like is infiltrated onto the hydrophilic substrate film to swell the film and the resin, residual stress is released and the antistatic tape easily peels off from the glass surface of the liquid crystal substrate. .

[0030]

Embodiments of the method of the present invention will be described in detail below with reference to the accompanying drawings.

1 and 2 show a liquid crystal substrate protection structure according to the method of the present invention. The liquid crystal substrate 10 is provided with an antistatic tape 20 and a conductive film 30 which are attached or superposed on the front and bottom surfaces of the liquid crystal substrate 10. Especially the terminal part 1 of the circuit
1 protects 1 from electrostatic charge.

More specifically, the antistatic tape 20 is composed of a tape base material 21 and an adhesive 22, and the materials used specifically will be described later.

The conductive film 30 is formed by vapor-depositing metal such as vapor-deposited aluminum 32 or a metal foil on one surface of the plastic film 31.

First, as shown in FIG. 1, the bottom surface of the liquid crystal substrate 10 is overlapped with the metal vapor deposition (or metal foil) 32 surface of the conductive film 30 which is cut out to be larger than the surface area of the liquid crystal substrate 10 and used in the present invention. The antistatic tape 20 is cut into a larger amount than the surface area of the liquid crystal substrate 10, and the adhesive 22
The surface is attached to the surface of the liquid crystal substrate 10.

The antistatic tape 20 protruding from the liquid crystal substrate 10 is bonded to the conductive film 30 on the opposite surface, which also protrudes from the liquid crystal substrate 10.

Further, as shown in FIG. 2, the antistatic tape 20 used in the present invention is cut out in a larger size than the surface area of the liquid crystal substrate 10, and the adhesive 22 surface thereof is bonded to the surface of the liquid crystal substrate 10 to form a liquid crystal substrate. Metal deposition (or metal foil) of the conductive film 30 that is cut out larger than the surface area of 10
The 32nd surface is attached to the bottom surface of the liquid crystal substrate 10. And
The conductive film 30 protruding from the liquid crystal substrate 10 is bonded to the antistatic tape 20 on the opposite surface, which also protrudes from the liquid crystal substrate 10.

The antistatic tape 20 may be cut into a suitable size and attached so as to cover only the terminal portion 11 of the liquid crystal substrate 10. As described above, the liquid crystal substrate 10
Is covered with an antistatic tape 20 and a conductive film 30 and transported in a state where protection from electrostatic charge is achieved, and then sprayed with a polar organic solvent such as water, warm water, acidic aqueous solution, alkaline aqueous solution or methanol. By doing so, or by immersing the entire surface, the antistatic tape 20 is promptly peeled off from the liquid crystal substrate 10.

Next, the specific structure of the antistatic tape 20 used in the present invention will be described below.

First, as the adhesive 22, <acrylic polymer 1> 40 parts by weight of butyl methacrylate, 40 parts by weight of ethyl acrylate, 10 parts by weight of acrylic acid, 5 parts by weight of 2-hydroxyethyl methacrylate,
After reacting 5 parts by weight of 4,4′-azobis-4-cyanovaleric acid under N _{2 at} 70 ° C. for 5 hours, 0.01 parts by weight of hydroquinone was added to obtain an acrylic polymer. The critical surface tension when this polymer is formed into a film is 38 dyn /
The cm and Mw were about 150,000.

<Acrylic polymer 2> 75 parts by weight of butyl methacrylate, 12.5 parts by weight of acrylonitrile, 7.5 parts by weight of acrylic acid, 2 parts by weight of 2-hydroxyethyl methacrylate, 4,4'-azobis-4-cyanovaleric acid 3 After reacting 4 parts by weight under N _{2 at} 70 ° C. for 4 hours,
An acrylic polymer was obtained by adding 0.01 part by weight of hydroquinone. The critical surface tension when the polymer was formed into a film was 33 dyn / cm, and the Mw was about 150,000.

<Acrylic Polymer 3> 40 parts by weight of butyl methacrylate, 40 parts by weight of ethyl acrylate, 12.5 parts by weight of acrylamide and 7.5 parts by weight of 2-hydroxyethyl methacrylate were reacted under N _{2 at} 70 ° C. for 4 hours. And 0.01 parts by weight of hydroquinone were added to obtain an acrylic polymer. The critical surface tension when the polymer was formed into a film was 35 dyn / cm, and the Mw was about 75,000.

<Acrylic Polymer 4> 30 parts by weight of butyl methacrylate, 50 parts by weight of ethyl acrylate, 10 parts by weight of acrylic acid and 10 parts by weight of 2-hydroxyethyl methacrylate were reacted under N _{2 at} 70 ° C. for 5 hours, and then hydroquinone 0 was added. An acrylic polymer was obtained by adding 0.01 part by weight. The critical surface tension when the polymer was formed into a film was 44 dyn / cm, and the Mw was about 650,000.

<Acrylic polymer 5> 40 parts by weight of butyl methacrylate, 50 parts by weight of ethyl acrylate, 2-
10 parts by weight of ethylhexyl acrylate at 70 ° C. under N ₂
After reacting for 5 hours, 0.01 part by weight of hydroquinone was added to obtain an acrylic polymer. The critical surface tension when the polymer was formed into a film was 28 dyn / cm, and the Mw was about 450,000.

<Polyisobutylene 1> MML-120
(Polyisobutylene manufactured by Exxon Chemical Co., Ltd.) was used.
The critical surface tension of this polymer formed into a film is 29 dy.
The n / cm and Mw were about 100,000.

<Aromatic polyfunctional isocyanate 1> Trimethylolpropane tris- (tolylene diisocyanate) <Aromatic polyfunctional isocyanate 2> Tolylene diisocyanate <Aliphatic polyfunctional isocyanate 3> Trimethylhexamethylene diisocyanate A predetermined amount of functional isocyanate was mixed and stirred. This resin composition has a thickness of about 40 μm.
On the PVA film, cellophane film or kraft paper that is the tape base material 21 of
And was heated at 90 ° C. for 20 minutes. The obtained composition was aged in air at 80 ° C. for 12 hours, and the following Examples 1 to 6 and Comparative Examples 1 to 5 were obtained.
Each of the antistatic tapes 20 was produced.

After that, the liquid crystal substrate 10 whose chamfering process has been completed by the above-mentioned method is combined with the antistatic tape 20 and 0.05 μm.
The conductive film 30 made of the film 31 having the aluminum layer 32 of m deposited therein was sandwiched, and a predetermined amount of static electricity was forcibly applied by the static electricity generator to measure the withstand voltage of the antistatic tape 20. After the measurement, the antistatic tape 20 was immersed in distilled water and peeled off, and the surface condition of the liquid crystal substrate 10 was observed.

[Example 1] Acrylic polymer 1 100 parts by weight Polyfunctional isocyanate 1 2.5 parts by weight Tape base material PVA 30 μm [Example 2] Acrylic polymer 2 100 parts by weight Polyfunctional isocyanate 1 7.5 parts by weight Tape base material PVA 30 μm [Example 3] Acrylic polymer 3 100 parts by weight Polyfunctional isocyanate 2 2.5 parts by weight Tape base material PVA 30 μm [Example 4] Acrylic polymer 4 100 parts by weight Polyfunctional isocyanate 3 5 parts by weight Tape base material PVA 30 μm [Example] 5] Acrylic polymer 1 100 parts by weight Polyfunctional isocyanate 1 5 parts by weight Tackifier YS Polystar T-100 (terpene phenol; manufactured by Yasuhara Yushi Co., Ltd.) 5 parts by weight Tape base material cellophane 30 μm [Example 6] Acrylic polymer 2 100 parts by weight Cyanate 1 7.5 part by weight tackifier Hitanoru 2084 (alkylene phenol, manufactured by Hitachi Chemical Co., Ltd.) 5 parts by weight base tape kraft paper 100μm

[Comparative Example 1] Acrylic polymer 2 100 parts by weight Polyfunctional isocyanate 1 7.5 parts by weight Tape base material PVA 30 μm [Comparative example 2] Acrylic polymer 5 100 parts by weight Polyfunctional isocyanate 1 5 parts by weight Tape base material PVA 30 μm [ Comparative Example 3 100 parts by weight of acrylic polymer 1 Tape base material PVA 30 μm [Comparative example 4] 100 parts by weight of acrylic polymer 2 20 parts by weight Polyfunctional isocyanate 1 30 μm tape base material PVA 30 μm [Comparative example 5] 100 parts by weight of acrylic polymer 2 Polyfunctional isocyanate 25 parts by weight Tape base material PE 30 μm

Table 1 shows the withstand voltage of each antistatic tape 30, the peeling time, and the surface tension of the liquid crystal substrate 10 after peeling.
Shown in

[0050]

[Table 1]

[0051]

As described above, according to the method of preventing static electricity of a liquid crystal substrate according to the present invention, as is clear from the results of Table 1, the antistatic property and the change in surface tension of the liquid crystal substrate after peeling are small. After use, it can be easily peeled off with water, which is a very effective method for countermeasures against static electricity when moving and transporting liquid crystal substrates.

[Brief description of drawings]

FIG. 1 is a sectional view showing a protective structure of a liquid crystal substrate according to the method of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of another embodiment of the liquid crystal substrate protection structure according to the method of the present invention.

[Explanation of symbols]

 10 Liquid Crystal Substrate 11 Terminal 20 Antistatic Tape 21 Tape Base Material 22 Adhesive 30 Conductive Film 31 Plastic Film 32 Evaporated Aluminum

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasushi Oyama 1150 Gozamiya, Shimodate City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Inside the Yuki Plant

Claims (4)

[Claims] 1. A conductive film, a liquid crystal substrate, and an antistatic tape having antistatic properties, pressure-sensitive adhesive properties, and water swelling properties, at least a circuit terminal portion of the liquid crystal substrate being covered with the antistatic tape, and , The antistatic tape adheres to the conductive film placed on the bottom surface of the liquid crystal substrate to protect the circuit terminal part of the liquid crystal substrate, and after use, water, hot water, acidic aqueous solution, alkaline aqueous solution or polar organic solvent An antistatic method for a liquid crystal substrate, characterized in that the antistatic tape and the conductive film are peeled off from the liquid crystal substrate by means of. 2. The antistatic tape comprises a tape base material and an adhesive composed of the following composition coated on the liquid crystal substrate side of the tape base material. Antistatic method for liquid crystal substrates. The main component of the skeleton is composed of an acrylic acid ester copolymer, has at least one kind of functional group of a hydroxyl group, a carboxyl group or an amino group, and has a weight average molecular weight of 50,000 or more to form a film. The critical surface tension of the adhesive surface is 32 dyn /
With respect to 100 parts by weight of the acrylic polymer that is cm or more,
A composition comprising 0.1 to 10 parts by weight of an isocyanate compound having at least two isocyanate groups in one molecule. 3. The composition according to claim 2, wherein the composition is in the range of 10 to 60 parts by weight of ethyl acrylate and 90 to 40 parts by weight of butyl acrylate as an essential component of the copolymerization composition of acrylic acid ester. Antistatic method for liquid crystal substrates. 4. The antistatic method for a liquid crystal substrate according to claim 1, wherein the tape base material of the antistatic tape is a composition made of polyvinyl alcohol, cellophane or paper.