JPH10219222A - Microcapsule type adhesive particle for adhesion of liquid crystal display panel board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject particles used for adhering and fixing two liquid crystal display panel boards in a uniform fine interval by regulating the average particle diameter of microcapsules and membrane thickness of the wall membrane so as to be within a specific region. SOLUTION: This microcapsule type adhesive particles are constituted of spherical microcapsules having a microcapsule core material comprising a homogenous mixture of (A) an epoxy resin-based adhesive, (B) an elastic reinforcing material and (C) a heat-activating type latent hardener encapsulated with resin wall membranes, and have membrane thicknesses of the wall membranes within the range of 0.005-1μm and average particle diameter within the range of 1.5-10μm. The component B is preferably at least one of epoxy resins of glycidyl ester type of dimer acid, a polypropylene glycol type and a nuclear- containing polyol type.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microcapsule-type heat-adhesive particle used for adhering and fixing two liquid crystal display panel substrates at a uniform minute interval. The present invention also relates to such a method for bonding substrates.

[0002]

2. Description of the Related Art In a liquid crystal display panel, liquid crystal is sealed in a flat cell formed between two glass or plastic plates, and an electrode is formed on the inner surface of the glass or plastic substrate. It is common to have a structure in which a film is provided to control the orientation of the liquid crystal in the cell. The spacing between such two substrates corresponds to the thickness of the encapsulated liquid crystal layer. If cells are not formed so that the thickness of the liquid crystal layer is uniform over the entire panel, the liquid crystal response speed will vary due to poor alignment of the liquid crystal, and the display screen will become unclear and uneven. Is generated.

In particular, when the liquid crystal is a ferroelectric liquid crystal (FLC), the thickness of the liquid crystal layer is about 1.2 μm, and when the liquid crystal is a super twisted nematic liquid crystal (STN), the thickness of the liquid crystal layer is 5 μm.
And the interval between the panel substrates usually needs to be very narrow so as to be in the range of 1 to 8 μm. For this reason, as described above, securing uniformity of the substrate spacing is a major issue in liquid crystal panels. Furthermore, when the liquid crystal panel surface is a large screen such as 10 inches, not only the uniformity of the substrate spacing but also the securing of mutual fixation between the front substrate and the rear substrate has become an important issue. .

[0004] In order to solve such a problem, several proposals have conventionally been made. For example,
Japanese Patent Application Laid-Open Publication No. H11-163873 discloses a spherical particulate adhesive whose main component is at least an epoxy resin, wherein the epoxy resin contains a latent curing agent inside the particles, and is partially cured with a water-soluble amine-based curing agent. An epoxy-based spherical particulate adhesive characterized by the following has been proposed. It is preferable that the average particle size of the spherical particulate adhesive is 0.3 to 500 μm. Such an adhesive in the form of microsphere-like particles is dispersed on a liquid crystal panel substrate together with silica or other inorganic spacer particles having a defined particle size, and is then placed under pressure after further laminating another substrate. It can be used to heat and bond and fix both substrates at regular intervals.

The production of the particulate adhesive disclosed in Japanese Patent Publication No. 4-2637 requires that after the emulsion of the epoxy resin is formed, the surface and a part of the interior of the epoxy resin particles are partially cured with a water-soluble amine curing agent. Therefore, it has a drawback that it is complicated, requires more than one month to manufacture, is not suitable for mass production, and is expensive. Further, the particulate adhesive disclosed in Japanese Patent Publication No. 4-2637 has a strong tackiness even after its partial curing, so that it is difficult to monodisperse the particles.

[0006] Therefore, the particles are agglomerated and scattered when sprayed. Therefore, when the partial curing of the particulate adhesive is further strengthened, segregation and separation of various components such as a curing agent occur inside the particles, and an adhesive having good adhesiveness, elasticity, dispersibility, and orientation is obtained. I couldn't.

Japanese Patent Application Laid-Open No. 57-29031 discloses that a microencapsulated adhesive is scattered together with spacer particles between a front substrate and a rear substrate of a liquid crystal display panel, and then the adhesive is applied to both substrates. A liquid crystal display panel having a structure sealed by pressure and heat is described.

The microencapsulated adhesive proposed in JP-A-57-29031 uses gelatin, urethane or epoxy resin as a wall material of the microcapsule and an epoxy resin adhesive as a core material adhesive. However, there is no description in JP-A-57-29031 of a concretely manufactured embodiment of the microencapsulated adhesive proposed here.

[0009] The inventors of the present invention have conducted additional tests on the microencapsulated adhesive disclosed in Japanese Patent Application Laid-Open No. 57-29031, and found that when gelatin is used as the microcapsule wall film material, Generally, gelatin requires a method for producing microcapsules by a phase separation method, so that the film thickness of the gelatin wall is absolutely too thick. It was confirmed that the microcapsules whose wall film was made of gelatin did not collapse even when heated and pressed, and showed practically no adhesive strength. Gelatin is a substance mainly composed of collagen and has high ionicity.
LC or STN liquid crystal is also not preferable because it adversely affects the liquid crystal. On the other hand, when urethane is used as the microcapsule wall film material, the urethane is a thermosetting resin with a high glass transition temperature of 150 ° C or higher. However, there was a defect that the internal epoxy resin-based adhesive could not flow out to the contact interface with the substrate and did not exhibit any adhesive force.

Further, when an epoxy resin is used as a wall film material instead of the urethane resin, the epoxy resin is cured to a certain extent and is effective as a wall material film for covering a core material which is an epoxy resin adhesive. When this was done, it was recognized that the epoxy resin wall material film exhibited the same defects as in the case of urethane resin.

[0011]

SUMMARY OF THE INVENTION To solve the practical disadvantages of the adhesive particles or microencapsulated adhesive disclosed in the above-mentioned publication used for bonding a liquid crystal panel substrate proposed in the above prior art. The present inventors have conducted various studies to create a novel particulate adhesive or adhesive particles that can be satisfactorily used for bonding a liquid crystal display panel substrate. As a result, it was recognized that it was a good idea to make a new improvement to the microencapsulated adhesive, and the wall material and wall thickness of the microcapsule, the composition of the core material adhesive, and the microcapsule diameter Various factors were considered. The present inventors have devised the following novel microcapsule-type adhesive particles for bonding a liquid crystal display panel substrate.

[0012]

According to a first aspect of the present invention, there is provided a microcapsule core material comprising a homogeneous mixture of an epoxy resin-based adhesive, an elasticity-enhancing agent, and a heat-activated latent curing agent. Are adhesive particles formed in the form of spherical microcapsules covered with a resin wall material film having a glass transition temperature in the range of 60 to 120 ° C., and the microcapsule wall material film 0.00
Microcapsule-type adhesive particles for bonding a liquid crystal display panel substrate are provided, wherein the adhesive particles are in the range of 5 μm to 1 μm and the average particle size of the microcapsules is in the range of 1.5 μm to 10 μm. .

The microcapsule-type adhesive particles according to the first aspect of the present invention are interspersed with spacer particles having a constant particle size between two liquid crystal display panel substrates, and then the substrates are bonded by heating under pressure. By fusing and fixing the conductive particles, the front substrate and the rear substrate are firmly bonded together while securing a uniform fine spacing suitable for forming a liquid crystal layer of uniform thickness over the entire surface of the substrate. It can be used.

Next, a specific method for using the microcapsule type adhesive particles of the first invention for bonding a liquid crystal display panel substrate will be described, and in connection with this, the present invention will be described. The structure and the effect of the adhesive particles will also be described.

That is, when using the microcapsule-type adhesive particles of the present invention, they are dispersed together with spacer particles in a liquid dispersion medium, for example, isopropyl alcohol, to prepare a dispersion. When the dispersion liquid is uniformly applied to the electrode surface of the panel substrate and then the dispersion medium is evaporated, the adhesive particles and the spacer particles of the present invention are scattered on the substrate. In this case, generally, the adhesive particles of the present invention having a larger particle size than the spacer particles are used. Next, the second substrate is overlaid, pressure is applied between the two substrates, and heating is performed to fuse the adhesive particles to both substrates. The adhesive particles of the present invention can increase elastic strain due to the elastic reinforcing agent contained therein,
Even under pressure, the spacer particles are not broken between the substrates, and the substrates are bonded and fixed together in a state where the distance between the substrates is uniformed to the length of the diameter of the spacer particles. The adhesive particles of the present invention scattered between the substrates are such that a portion of the microcapsule wall material film is selectively destroyed at a contact interface with the substrate by pressurization and heating through the substrate, and the internal epoxy It is necessary that the resin adhesive and the latent curing agent flow out to the substrate contact interface. However, in general, when the diameter of the microcapsules is in a very small range of 1.5 to 10 μm, it is necessary to apply a pressure of 300 to 1000 kg / cm ² to mechanically break the microcapsules. When such a microcapsule is in contact with a glass substrate, it is very difficult to mechanically break the microcapsule because pressure cannot be concentrated at one point, and in some cases, the glass substrate itself is broken.

The adhesive particles of the present invention are designed so that the microcapsule wall material film is made of a resin having a glass transition temperature of 60 to 120 ° C. so that it can be melt-ruptured under pressure and heat. Was. In the interfacial region where the microcapsules of the present invention are in contact with the glass substrate, the strongest heat energy is obtained by heat conduction to soften and the elongation pressure is concentrated. And be destroyed.

Furthermore, the adhesive particles of the present invention are in the form of microcapsules, and are covered with the above-mentioned resin microcapsule wall material film.
It has the advantage of preventing aggregation of the adhesive particles, maintaining high dispersibility of the microcapsules in a dispersion liquid dispersed in isopropyl alcohol or other liquid, and being able to be monodispersed and dispersed as a single particle on a substrate. .

Further, the microcapsule wall material film of the adhesive particles of the present invention is softened in a contact interface region with the substrate at a processing temperature of 120 to 150 ° C. by pressurizing and heating the substrate after being sprayed on the substrate. Although it is necessary to melt and break it, after the adhesive curing reaction between the latent curing agent in the microcapsule and the epoxy adhesive, it is cooled down to room temperature again, so that it maintains a certain hardness and also contacts the liquid crystal Therefore, it must be made of a resin that has good compatibility with the liquid crystal and does not hinder the alignment of the liquid crystal.

In the present invention, the glass transition temperature (T _G ) of the microcapsule wall material which can satisfy the above conditions is as follows.
A resin having a temperature of 60 ° C. or higher and a temperature of 120 ° C. or lower, which is lower than the above pressurizing / heating temperature of 120 to 150 ° C., was selected. When the _{TG of the} resin is less than 60 ° C., the surface of the microcapsules is softened and adhered at around normal temperature, and the microcapsules are easily aggregated, which is inappropriate.

On the other hand, if the _{TG of the} resin is higher than 120 ° C., the microcapsule wall is not sufficiently softened to adhere to the substrate and is not broken because the temperature is higher than the heat treatment temperature.

In the adhesive particles of the microcapsule type according to the present invention, as the adhesive encapsulated as a core substance in the microcapsules, a known adhesive containing an epoxy resin as a main component is used. This epoxy adhesive is a bisphenol A type-diglycidyl ether type epoxy resin or a condensed bisphenol A-diglycidyl ether type epoxy resin, or a polyglycidyl ether of a phenol novolak type compound, a diglycidyl ether of polyethylene glycol, a bisphenol F type. Diglycidyl ether or glycidylamine resins are suitable.

The latent curing agent mixed with the epoxy resin adhesive as the core material of the microcapsule of the present invention is stable at room temperature and has no curing effect, but activates when heated. Those which cause a curing reaction at 120 to 150 ° C are preferred. Specific examples of such a curing agent include a polyamine salt (for example, a salt of phenylphosphonic acid and o-phenylenediamine or a salt of phenylphosphoric acid and p-phenylenediamine), melamine and a derivative thereof (for example, diallyl melamine). , Diaminomaleonitrile and its derivatives, BF ₃ -monoethylamine complex, or phenolic compounds (for example, diglycidyl ether of phenol novolaks or adducts of condensates thereof with bisphenols) and the like are suitable.

In the microcapsule-type adhesive particles of the present invention, if the core material is composed of a mixture of only the epoxy resin-based adhesive and the curing agent, the mechanical strength at the time of pressurization and heating is insufficient, Further, since the impact resistance of the panel is not sufficient, it is necessary to additionally add an elasticity reinforcing agent to the core material. Such an elastic reinforcing agent is an epoxy resin having a low elastic modulus, specifically, a dimer acid type epoxy resin (diglycidyl ester type), a polypropylene glycol type epoxy resin, or a bisphenol side chain type epoxy resin [bisphenol A is propylene Epoxidized nucleated polyol to which oxide has been added]. In addition, the said dimer acid points out what dimerized by heating the long-chain unsaturated fatty acid obtained by hydrolysis of fats and oils. It is preferable to add 2 to 30% by weight of the elastic reinforcing agent to the epoxy resin adhesive as the main component. Thereby, the elastic modulus of the microcapsules of the adhesive particles of the present invention is 20 to
35 mgf / μm ² , giving excellent impact resistance.

The resin forming the microcapsule wall material film of the adhesive particles of the present invention needs to have a glass transition temperature of 60 to 120 ° C. in order to obtain various effects as described above. As the resin for the wall material film, polymethyl methacrylate (PMMA), polystyrene, polyamide, polyvinyl alcohol (PVA), polyvinyl chloride (PVC), polyethylene (PET), polypropylene and the like are suitable. This wall material film can be a composite wall film composed of two or more layers of different materials.

Further, even if a thermosetting resin is usually seen, a polymer having a linear structure without forming a three-dimensional network and having a glass transition of 60 to 120 can be obtained by devising the synthesis conditions. It is known that a resin at ℃ can be produced,
Such a resin can be used as a microcapsule wall film material in the present invention.

In the adhesive particles of the present invention, a preferable example of the resin forming the wall material film of the microcapsule is a mixture of urea and melamine and formaldehyde, with 1.2 to 1.7 parts of formaldehyde per part of the mixture. A glass formed by using a prepolymer produced by partially condensing a blend obtained by blending in a certain ratio by weight, and polymerizing the prepolymer by an in situ polymerization method under acidic conditions at the time of preparing microcapsules. It is a linear urea-melamine-formaldehyde resin having a transition temperature of 60 to 120 ° C.

The thickness of the wall material film of the microcapsules which are the adhesive particles of the present invention is in the range of 0.005 μm to 1 μm. If the thickness is more than 1 μm, the microcapsules having a diameter of 1.5 μm to 10 μm are hard to break. Further, even if it is broken, the adhesion between the mixture containing the epoxy resin adhesive and the wall material film, which forms the core substance, becomes weak and peels off, and fragments are generated, which adversely affects the liquid crystal, which is inconvenient.

On the other hand, if the film thickness is less than 0.005 μm,
When the core material in the microcapsule contains epoxy resin that has fluidity at around room temperature, the function of solidifying granules is insufficient,
It is difficult to maintain the particle form, the aggregation between the particles becomes very large, the dispersibility of the particles becomes worse, the adhesion between the substrates becomes non-uniform and the fixability is bad, and not only the liquid crystal panel image becomes uneven, but also In addition, the panel life is shortened.

Further, the average diameter of the adhesive particle microcapsules of the present invention is in the range of 1.5 to 10 μm, preferably in the range of 2 to 8 μm. For this, a value slightly larger than the thickness of the liquid crystal layer determined in consideration of the orientation of the liquid crystal depending on the type of the liquid crystal, that is, the particle diameter of the spacer particles is selected. For example, in the case of FLC liquid crystal, since the diameter of the spacer particles is 1.2 μm, the diameter of the microcapsules of the adhesive particles of the present invention is preferably about 4 μm. In the case of STN liquid crystal, since the particle size of the spacer particles is 5 μm, the microcapsule particle size of the adhesive particles of the present invention is 8 μm.
Those having a size of about μm are suitable.

In the present invention, the fluctuation range of the diameter of each microcapsule is within ± 25% of the average particle diameter, or 80% or more of the microcapsules in terms of the number-based cumulative distribution of the diameter of each microcapsule. It is preferable that the particles have a diameter whose number falls within ± 25% of the median average particle diameter.

If the variation range of the particle diameter of each microcapsule is larger than the above value, for example, if the diameter of the microcapsules is smaller than that of the spacer particles, the particles cannot be pressed and held between the substrates, and the adhesive floating in the liquid crystal will not be adhered. This is not preferred because it produces conductive particles. In addition, when the diameter is large, the influence of the adhesive particles is detected by the naked eye as white slime, bleeding, or the like on the panel surface.

Further, if the diameter of each of the microcapsules of the adhesive particles of the present invention has a large fluctuation range, the capsules are destroyed in a nonuniform manner, resulting in a difference in the adhesive strength between the panel positions, and a panel joined body. Even then, the adhesive strength between the substrates becomes insufficient.

The microcapsule-type adhesive particles according to the present invention can be produced by using a known microcapsule production technique. That is, a well-known method using a homogeneous mixture of the above-mentioned adhesive, curing agent and elasticity reinforcing agent as a core material to be microencapsulated, and using a resin of the above-described type for forming a microcapsule wall material film. With interfacial polymerization method,
The microcapsule-type adhesive particles of the present invention can be prepared by an interfacial precipitation method, an in situ method, a spray drying method, a liquid, air curing method, coacervation or other methods.

In the case of preparing microcapsules by the interfacial polymerization method, a hydrophobic monomer and a hydrophilic monomer are generally used in combination, and when both types of monomers are polymerized in water, the hydrophobic reaction is caused by the interfacial reaction. A microcapsule wall is formed from the reactive monomer. For example, in the case of preparing the microcapsules of the present invention, a mixture of a monomer for forming a resin adhesive, a curing agent and a monomer for forming an elastic reinforcing agent is used as a core substance, a polybasic acid halide is used as an oil-soluble monomer, and a water-soluble monomer is used. By using polyamine as a monomer and performing an interfacial reaction while polymerizing them in water, microcapsules having a polyamide wall film that covers the resin of the core substance can be obtained.

In the in situ method, a monomer or prepolymer for forming a wall material film and a catalyst are dissolved in two phases that do not mix with each other, for example, one of an oil phase and an aqueous phase. In this method, both phases are forcibly stirred to form an emulsion so that the monomer or prepolymer causes a polymerization reaction at the interface, thereby forming a uniform wall material film on the surface of the fine particles composed of the core material.

For example, an epoxy resin forming a core material,
Using a mixture of a latent curing agent and an elasticity reinforcing agent as an oil phase, and using an aqueous solution containing a melamine-urea prepolymer and an acidic catalyst as an aqueous phase, and mixing and heating these two phases under stirring. Then, a urea-melamine-formaldehyde condensate film is formed as a wall material film on the surface of the core substance fine particles.

When it is desired to form a styrene wall material film, while stirring an aqueous solution containing gum arabic as a dispersant, a polymerization initiation catalyst (such as uraroyl peroxide), a styrene monomer, an epoxy resin, It is obtained by adding a reactive curing agent, an elasticity enhancer, and divinylbenzene, and reacting them under a nitrogen atmosphere. Similarly, a wall material film made of polymethyl methacrylate (PMMA) can be prepared.

The interfacial precipitation method is a method also called a secondary emulsion method, in which a polymer that has been polymerized in advance is (W / O) W
Alternatively, a capsule wall is formed by using an (O / W) O type emulsion. A microcapsule wall film can be formed with polystyrene and styrene maleic acid derivatives.

The spray drying method is a method in which an emulsion of a core substance and an emulsion of a wall substance are simultaneously sprayed, brought into contact with hot air, and evaporated to dryness to obtain microcapsules. IN SITU method, interfacial polymerization method,
An emulsion containing microencapsulation prepared by an interfacial precipitation method or a coacervation method may be used as a stock solution to be sprayed. In the case of direct microencapsulation, a triple nozzle is used.The core material emulsion is sprayed from the center nozzle, the wall material emulsion is sprayed from the outer nozzle, and compressed and dried air is sprayed from the outermost nozzle. This is a method of microencapsulation. PMMA and polystyrene walls can be formed by microcapsules.

In preparing the microcapsules of the present invention,
In the various methods of microencapsulation, the wall thickness of the microcapsules is determined by the concentration ratio or the mixing ratio of the core material and the wall material,
Alternatively, a predetermined wall thickness can be obtained by strictly selecting and controlling the concentrations of the core substance and the wall substance with respect to the reaction solution, or various reaction conditions (catalyst amount, pH, temperature, time, etc.).

In order to adjust the particle diameter of the microcapsules, in addition to the above conditions, the strength of the stirring speed of the reaction system, the shape of the reaction tank, the diameter of the spray nozzle, the pressure, etc. are strictly selected and controlled. Is obtained.

When the core material is used in the form of an emulsion and microencapsulated, a predetermined particle size can be achieved by controlling the type and amount of the surfactant, the emulsification temperature, the rotation speed of the reaction tank, and the like. .

If necessary, the microcapsules thus prepared may have a particle size using a wet classification method such as a water-evaporation method or a centrifugal separation method, or a dry classification method such as a cyclone method or a turbojet method. By separately classifying, microcapsule adhesive particles having a predetermined particle size can be obtained.

Next, the method of using the microcapsule type adhesive particles according to the first invention will be described with reference to FIGS. 1, 2 and 3 of the accompanying drawings.
Will be described.

FIG. 1 shows a microcapsule-type adhesive particle 3 of the present invention and a spacer particle 4 on a front substrate 1 provided with an electrode layer 2 used for manufacturing a liquid crystal display panel.
Are scattered, and then the back substrate 1 'on which the electrode layer 2' is provided is superposed. Each microcapsule particle 1 is composed of a core material 5 and a microcapsule wall material film 6.
Having. The microcapsule-type adhesive particles and the spacer particles may be scattered on the rear substrate first, and then the front substrate may be overlapped.

FIG. 2 shows the arrangement when the substrates 1 and 1 ′ are pressurized so that the distance between the substrates matches the particle size of the spacer particles 4 and the microcapsule particles 3 are somewhat flattened. Show.

FIG. 3 shows a state in which the wall material film 6 of the microcapsule particles 3 is broken between the substrates 1 and 1 'in the region of the contact interface with the substrate, and the core material 5 flows out and adheres to the inner surface of the substrate. The following shows the arrangement.

The microcapsule type adhesive particles according to the present invention, when bonding a liquid crystal display panel substrate, selectively break the microcapsule wall material film only in the region of the contact interface with the substrate, and the internal adhesive The agent-containing core material flows out to create a state of contact with the inner surface of the substrate, and operates uniquely to allow the adhesive reaction to proceed and complete.

Therefore, in the second aspect of the present invention, the electrode layer used for manufacturing a liquid crystal display panel is provided on the electrode layer side surface of the first panel substrate provided on the inner surface. The above microcapsule-type adhesive particles, and spacer particles having a defined particle size in the range of 1.2 μm to 5 μm are scattered and adhered, and then the electrode layer and the conductive film are formed on the inner surface in the same manner. The second panel substrate having the structure is superimposed and held on the first panel substrate at a position parallel to the direction in which the electrode layers are directed inward, and both superimposed substrates are pressed from the outside under pressure. The microcapsule-type adhesive particles are compressed and flattened between the panel substrates, but the length of the interval between both panel substrates matches the particle size of the spacer particles. In the position While softening, the portion of the wall material film of the microcapsule-type adhesive particles is softened and broken under the action of pressure and heat only in the region in contact with the inner surface of the panel substrate. The core material of the microcapsule directly in contact with the inner surface of the substrate in the area where
In addition, the microcapsule wall material film is left unbroken in a place other than the contact area, and is further heated under pressure until the adhesive bonding reaction between the core material and the inner surface of the substrate in contact with the core material is completed. This provides a method for bonding substrates of a liquid crystal display panel, which comprises bonding and fixing both substrates by point bonding with the adhesive particles while maintaining a uniform and minute gap.

[0050]

Next, the present invention will be described in detail with reference to examples.

Example 1 90 parts by weight of a bisphenol A-diglycidyl ether type epoxy resin (adhesive) and 10 parts by weight of a commercially available glycidyl ester dimer acid type epoxy resin (elasticity enhancer)
1: 1 of phenylphosphonic acid and O-phenylenediamine
A homogeneous mixture with 20 parts by weight of the mixture (latent curing agent) was prepared. This mixture was dispersed in pure water together with 10 parts by weight of polyoxyethylene alkylphenyl ether (surfactant) to prepare an emulsion for forming a microcapsule core material.

On the other hand, by subjecting methyl methacrylate to suspension polymerization in the presence of a benzoyl peroxide polymerization catalyst, 44% (weight) dispersed particles of polymethyl methacrylate (PMMA) having a degree of polymerization of about 800 are contained. The aqueous suspension was prepared as a suspension for the formation of the microcapsule wall membrane.

Using a triple nozzle commonly used for preparing microcapsules by spray drying, the above-mentioned emulsion for forming a core substance was sprayed through a central tube of the triple nozzle. Simultaneously, the PMMA suspension is sprayed through the second pipe of the triple nozzle and heated air (air gauge pressure 1 kg) is passed through the outermost third pipe of the nozzle.
/ Cm ² under pressure). The feeding speed of the emulsion and the suspension was adjusted to 20 ml / min, and the surface drying temperature of the sprayed liquid particles was adjusted to 80 ° C.

In this manner, microcapsule-type adhesive particles were prepared in which the core substance was a homogeneous mixture of the above-mentioned adhesive resin, elastic reinforcing resin, and curing agent, and the wall material film was PMMA.

When the physical properties of the microcapsules were evaluated, the glass transition temperature of the microcapsule wall film was 105 ° C., the wall thickness was 0.05 μm, and the median average particle size (number basis,
D ₅₀ ) is 8 μm, and the diameter variation range of the microcapsules is ± 23.
%Met.

The above microcapsules were used as the adhesive particles of the present invention and dispersed in isopropyl alcohol in an amount of 5% (weight / volume) together with silica spacer particles having a particle size of 5 μm to obtain a dispersion. On a glass substrate equipped with an electrode layer for a 10-inch liquid crystal display panel,
The dispersion was sprayed and applied so that the amount of the adhesive particles (microcapsules) in the amount of mg was evenly sprayed. The isopropyl alcohol was evaporated from the coating film by heating and dried. Laminate the second substrate and pressurize at 130 ℃, 2
After heating for a time, the substrate was bonded.

The obtained bonded substrate has a uniform spacing of 5 μm between the substrates, an excellent adhesive strength of 40 kg, and an elastic modulus of 25 mgf / μm ² , which is excellent in durability. Excellent impact properties.

Further, an STN liquid crystal was sealed in the cell between the substrates of the above-prepared substrate assembly to produce a liquid crystal display panel. When an orientation test was performed on this panel, it was confirmed that the panel exhibited excellent performance and gave a very clear image.

Example 2 85 parts by weight of a commercially available condensed bisphenol A (having a condensed bisphenol moiety having a molecular weight of 1100) -diglycidyl ether type epoxy resin (adhesive) and a polypropylene glycol type epoxy resin (elastic reinforcing agent) A homogenous mixture of 15 parts by weight and 15 parts by weight of diallyl melamine (latent curing agent) was prepared, which was then combined with 5 parts by weight of polyoxyethylene alkyl phenyl ether (surfactant) in pure water and ethanol. To prepare a water-based emulsion for forming a microcapsule core material.

The aqueous emulsion was mixed with 45
% (Weight) in an organic solution of polystyrene obtained by dissolving in methine chloride. The resulting mixture is immediately
The mixture was dispersed by agitation at 1200 rpm for 30 seconds. The obtained dispersion was placed in a 3% aqueous solution of polyvinyl alcohol and reacted at 70 ° C. for 10 hours. Methylene chloride was degassed and removed from the reaction solution. Thus, the microcapsule-type adhesive particles of the present invention having the composite wall film composed of the polystyrene layer and the polyvinyl alcohol layer were obtained by the interface precipitation method.

When the physical properties of the above microcapsules were evaluated after dry classification, the microcapsule wall film had a glass transition point of 100 ° C., a wall thickness of 0.07 μm, a median average particle diameter (number basis, D ₅₀ ) of 5.0 μm. The diameter fluctuation range was ± 25%.

Further, the adhesion test of the panel substrate was performed in the same manner as in Example 1 to evaluate the adhesive strength of the bonded substrate. As a result, the adhesive strength was 35 kg, and the elastic modulus was 35 mgf /
μm ² , showing good impact resistance.

Further, it was recognized that the liquid crystal panel produced by sealing the FLC liquid crystal in the cell of the substrate joined body thus produced exhibited excellent liquid crystal orientation.

Example 3 Epoxidation of 97 parts by weight of a bisphenol A-diglycidyl ether type epoxy resin (adhesive) and a nucleated polyol obtained by adding propylene oxide to bisphenol A as a nucleated polyol type epoxy resin. A homogeneous mixture of 3 parts by weight of the obtained resin (elastic reinforcing agent) and 15 parts by weight of an adduct of diglycidyl ether of condensed bisphenol A as a phenolic latent curing agent and bisphenol A was prepared. This mixture was dispersed in pure water together with 7 parts by weight of polyoxyethylene alkylphenyl ether (surfactant) to prepare an emulsion for forming a microcapsule core material.

On the other hand, 1 part by weight of a (1: 1) mixture of urea and melamine was mixed with 1.5 parts by weight of formaldehyde, and the resulting liquid mixture was treated under alkaline conditions of pH 8.5 with 600 parts by weight.
A prepolymer for forming a microcapsule wall material film was prepared by carrying out the reaction for 2 hours with stirring at 65 ° C. and rpm. After diluting the prepolymer 10-fold with pure water, the emulsion for forming the core substance was added to the diluted solution,
Microcapsules were prepared by an in situ method by performing a polymerization reaction under acidic conditions of 00 rpm, 45 ° C. and pH 4.0 for 24 hours. The microcapsule-type adhesive particles of the present invention were obtained by further washing and dehydrating and separating. When the physical properties of this microcapsule were evaluated, the microcapsule had a glass transition point of 110 ° C. and a wall thickness of 0.1 ° C.
μm, median average particle size (number basis, D ₅₀ ) is 4.0μ
m, the diameter variation width of the microcapsules was ± 20%.

A microcapsule was added to isopropyl alcohol in an amount of 5% (weight / volume) to form a dispersion, which was sprayed on a substrate in the same manner as in Example 1, and a second substrate was overlaid and pressurized and heated ( (120 ° C., 2 hours) to bond the substrates. The obtained substrate joined body showed a very high adhesive strength of 45 kg. On the other hand, the elastic modulus of the bonded substrate was 30 mgf / μm ^2, which was an extremely excellent value of impact resistance.

Further, a panel in which an FLC liquid crystal was sealed was produced using this substrate assembly, and the orientation of the liquid crystal was observed. As a result, it was found that a very clear image was obtained.

[0068]

The adhesive particles of the present invention contain a viscous epoxy resin as the core material of the microcapsule, but are covered with the wall material film, and the particles do not stick and agglomerate. It has excellent dispersibility and is easily monodispersed.

The wall material of the microcapsule, the particle size,
Because the fluctuation width and core material composition are well selected, when used for bonding substrates, the core material inside the microcapsule is melted and broken by pressurization and heating, and the core material inside contacts the substrate. It flows out to the interface, cures and undergoes an adhesive reaction. A very high adhesive strength of 35 to 50 kg can be exhibited by the substrate joined body. In addition, an extremely high impact resistance of the bonded substrate can be obtained.

Further, a resin for a microcapsule wall material film which is familiar with the liquid crystal without disturbing the liquid crystal can be selected.
When a substrate bonded with the adhesive particles of the present invention is used, a panel having excellent liquid crystal orientation can be obtained.

The microcapsule-type adhesive particles of the present invention require only about two to three days to produce, and can be produced in a short period of time, thus enabling a significant cost reduction. A black colorant can be mixed into the inside of the microcapsule of the present invention, and the contrast of the display image on the liquid crystal panel can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic view schematically showing an arrangement in which microcapsule-type adhesive particles and spacer particles of the present invention are scattered on a substrate with an electrode layer for a liquid crystal display panel, and a second substrate is overlaid.

FIG. 2 is a schematic diagram schematically showing an arrangement when two substrates are pressed until the adhesive particles between the two substrates shown in FIG. 1 are flattened.

FIG. 3 shows that the microcapsule wall material film of the adhesive particles between the two substrates shown in FIG. 2 is broken at the contact interface with the substrate,
FIG. 4 is a schematic diagram schematically showing an arrangement in which a core substance flows out and directly forms an adhesive portion with a substrate.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 front substrate 1 ′ back substrate 2 electrode layer 2 ′ electrode layer 3 microcapsule-type adhesive particles 4 spacer particles 5 microcapsule core material 6 microcapsule wall material film

Claims (6)

[Claims] 1. A microcapsule core material comprising a homogeneous mixture of an epoxy resin-based adhesive, an elastic reinforcing agent, and a heat-activated latent curing agent has a glass transition temperature in the range of 60 to 120 ° C. Adhesive particles configured in the form of spherical microcapsules covered with a resin wall material film, and the film thickness of the microcapsule wall material film is
Microcapsule-type adhesive particles for bonding a liquid crystal display panel substrate, wherein the adhesive particles are in the range of 0.005 μm to 1 μm and the average particle size of the microcapsules is in the range of 1.5 μm to 10 μm. 2. The adhesive particles according to claim 1, wherein the elastic reinforcing agent comprises at least one of glycidyl dimer acid epoxy resin, polypropylene glycol epoxy resin and nucleated polyol epoxy resin. 3. The resin forming the wall material film of the microcapsules is polymethyl methacrylate, polystyrene, polyamide, polyvinyl alcohol, polyvinyl chloride,
2. The adhesive particle according to claim 1, comprising at least one of polyethylene and polypropylene. 4. The resin forming the wall material film of the microcapsule is formed by mixing a mixture of urea and melamine with formaldehyde, and forming a mixture of the mixture of
A prepolymer produced by partially condensing a composition obtained by blending at a weight ratio in a range of 1.7 parts is used, and the prepolymer is prepared under acidic conditions during the preparation of microcapsules.
Glass transition temperature of 60 produced by itu polymerization
The adhesive particle according to claim 1, which is a linear urea-melamine-formaldehyde resin having a temperature of up to 120 ° C. 5. The variation range of the diameter of each microcapsule is within ± 25% of the average particle size, or 80% or more of the microcapsules in the number-based cumulative distribution of the diameter of each microcapsule are in the range of ± 25%. The adhesive particles according to claim 1, having a diameter falling within ± 25% of the average particle size. 6. The microcapsule-type adhesiveness according to claim 1, wherein an electrode layer used for manufacturing a liquid crystal display panel is provided on an inner surface of a first panel substrate on an electrode layer side. Particles and spacer particles having a defined particle size in the range of 1.2 μ to 5 μ are scattered and deposited,
Next, a second panel substrate having a similar structure in which the electrode layer and the conductive film are provided on the inner side surface is superimposed and held on the first panel substrate at a position parallel to the direction in which the electrode layers become inward. Then, the two superimposed substrates are heated while being pressed against each other from the outside under pressure, and the microcapsule-type adhesive particles are compressed between the panel substrates to form a flattened form. While maintaining the state in which the length of the interval between the spacer particles coincides with the particle diameter of the spacer particles, only the portion of the wall material film of the microcapsule-type adhesive particles that is in contact with the inner surface of the panel substrate is maintained. It softens and breaks under the action of pressure and heat, thereby bringing the core material of the microcapsule into direct contact with the inner surface of the substrate in the above-mentioned contact area. The cell wall material film is left in an unbroken state, and heating is continued under pressure until the curing and bonding reaction of the adhesive between the core material and the inner surface of the substrate in contact therewith is completed. A method for bonding substrates of a liquid crystal display panel, comprising bonding and fixing the adhesive particles by point bonding with uniform and minute intervals.