JPS63218780A - Powdery adhesive and powdery adhesive for liquid crystal element utilizing said adhesive - Google Patents

Abstract

PURPOSE:To obtain a powdery adhesive, having a component with a constant average particle diameter, substantially spherical shape, ethylenic double bonds in particles, hot melt and thermosetting properties and suitable as point bonding elements of liquid crystal elements. CONSTITUTION:The aimed hot melt and thermosetting type powdery adhesive having at least a component with 0.5-500mum (preferably 1-50mum) average particle diameter (preferably within 30% coefficient of variation of the particle diameter) in substantially spherical shape having ethylenic double bonds in particles (preferably polyfunctional maleimide, unsaturated polyester or polyfunctional oligoacrylate). Furthermore, the unsaturated polyester and polyfunctional oligoacrylate are preferably bisphenol based substances and the component having ethylenic double bonds is preferably an epoxy resin (preferably bisphenol based epoxy resin). The aimed adhesive is used for bonding or sealing glass, metal and electronic materials.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a powder adhesive that exhibits heat melting properties and is thermosetting.

Since the adhesive obtained in the present invention is in the form of spherical particles, it is particularly suitable as a powder adhesive for spot bonding between substrates in order to maintain a constant gap between the substrates of a liquid crystal element.

[Prior Art] As the display area of liquid crystal elements increases, for example, it becomes difficult to maintain a constant gap between substrates in a portion filled with liquid crystal, which causes image distortion. By fixing this part with a tiny particulate adhesive that is difficult to discern with the naked eye, it can be fixed without compromising the quality of the display.
This makes it possible to achieve larger scale.

As a spherical powder adhesive with a narrow particle size distribution,
In JP-A No. 10-208333, a polyolefin powder modified with an unsaturated carboxylic acid or a derivative thereof is used, and in JP-A No. 10-208334, a polyolefin powder modified with an unsaturated carboxylic acid or a derivative thereof is JP-A No. 61-57617 discloses a thermoplastic polyester powder. All of these powders are thermoplastic polymer powders.

[Problems to be Solved by the Invention] In any of the three disclosed techniques described above, even when used as a point adhesive for a liquid crystal display element, the powder after adhesion does not form a crosslinking bond.

In the polymer, a phenomenon of creeping under load is observed at -m. Creep is more likely to occur at higher temperatures, so in applications where the adhesive gap must be strictly maintained, polymers with glass transition temperatures significantly higher than the operating temperature must be used as adhesives. However, thermoplastic or linear polymers are unavoidable to creep even at temperatures below their glass transition point, and as with liquid crystal display devices (long-term stability tests have been conducted at temperatures exceeding 10°C), Therefore, point bonding with thermoplastic adhesive is not practical.In fact, when using thermoplastic adhesive, a phenomenon has been observed in which the gap between the substrates gradually changes during use of the liquid crystal display element. For large vertical screens,
A blistering phenomenon may be seen due to the gravitational movement of the liquid crystal toward the bottom of the screen.

In contrast, the present invention provides a powder adhesive capable of three-dimensional crosslinking, in which the adhesive gap is less likely to change due to creep during use.

[Means for Solving the Problems] In order to achieve the above object, the present invention has the following configuration.

That is, the present invention provides [(1) an average particle diameter of 0.5 to 500 μm, a substantially spherical shape, and at least a component having an ethylenic double bond in the particle, and A powder adhesive characterized by being a hot melt thermosetting type.

(2) A powder adhesive having an average particle size of 1 to 50 μm, a spherical shape with a particle size variation rate of within 30%, and at least a component having an ethylenic double bond in the particles. , a powder adhesive for liquid crystal elements, characterized in that it is used as a point adhesive for liquid crystal elements. ” regarding.

The polyfunctional maleimides preferably used in the present invention include diphenylmethane bismaleimide, diphenyl ether bismaleimide, 3.3°-dimethyldiphenylmethane bismaleimide, metaphenylene bismaleimide, paraphenylene bismaleimide, 2-methylmethane bismaleimide, Examples include phenylene bismaleimide, and phenol novolak-type polyfunctional maleimides are examples of bifunctional or higher functionality. These may be used alone or in combination, or in combination with a monofunctional maleimide.

Furthermore, it may be used in combination with a copolymerizable monomer having an allyl group or an acrylic group, such as 0,0°-diallylbisphenol A or oligoacrylates. but,
Preferably, these mixtures are in a compatible state. When the maleimide component is 20% by weight or more of the total weight, it exhibits strong adhesion to the polyimide alignment film on the substrate, and often exhibits excellent properties as a point adhesive between the substrates of a liquid crystal device.

In the present invention, unsaturated boreesters suitably used include terephthalic acid-propylene glycol-maleic acid copolymer, isophthalic acid-propylene glycol-maleic acid copolymer, and bisphenol A-propylene glycol-maleic acid copolymer. In particular, those containing bisphenols in their structure have high compatibility with the bisphenol-based epoxy resin described below, and are preferably used in the present invention.

Examples of polyfunctional oligoacrylates preferably used in the present invention include polyol acrylates, polyester acrylates, urethane acrylates, and epoxy acrylates, but particularly preferred in the present invention are bisphenol-based epoxy acrylates. It has bisphenols in its structure. This is because, as will be described later, it has high compatibility with bisphenol-based epoxy resins, and it is easy to improve the thermal meltability and toughness of the particles.

If the above-mentioned component having an ethylenic double bond is liquid at room temperature, or if it is solid but has a low molecular weight and exhibits brittle properties, it may be impossible to make it into particles, or
The drawback is that the particles are easily crushed after preparation. In such cases, the common method is to blend a component with a relatively large molecular weight that is solid at room temperature into the above component, but it is an important requirement that the component and the compounded component exhibit compatibility. .

Further, even if the components to be blended are liquid at room temperature, as long as they can be solidified by some means after blending, the components to be blended can be selected within the limited range of compatibility.

Among epoxy resins, bisphenol-based epoxy resins are most suitable as such components, and components with the above-mentioned ethylene and gender double bonds that are compatible with these include those that have bisphenols in their structures. It will be done. In this case, the bisphenol-based epoxy resin has a total of 80%
It is preferable to use it in an amount of about % by weight or less. When the amount of bisphenol-based epoxy resin used increases, the crosslinkability due to ethylenic double bonds decreases, and the crosslinking density decreases, which tends to impair creep resistance, which is the original objective.

Representative examples of methods for obtaining spherical objects from the aforementioned polyfunctional maleimides, unsaturated polyesters, polyfunctional oligoacrylates, and compatible mixtures of these and compounds such as bisphenol-based epoxy resins will be described below.

Generally, emulsion-mediated methods are preferred.

In this method, the compound to be spheronized is dispersed in a dispersion medium that is incompatible with the compound, and then the dispersed particles are solidified by some method to form spheroids.

When the compound for spheroidization, such as the above-mentioned polyfunctional maleimide, is a liquid or solution at room temperature, it is necessary to use a lipophilic or hydrophilic compound (water is sufficient in many cases) that is incompatible with it. It can be dispersed relatively easily in a dispersion medium. In such cases, the droplet particles after dispersion cannot be recovered as particles unless they are solidified, but as mentioned above, the method is to dissolve and blend in advance components that are compatible, have a relatively large molecular weight, and are solid at room temperature. It is possible that

When a polyester resin, acrylic resin, or epoxy resin is used as such a compounding component, it has high compatibility with -JR. Even if the epoxy resin is a liquid, it is necessary to add a curing agent in advance.
Same (No. 10-156717, No. 10-16391)
As disclosed in Japanese Patent No. 6, it is also possible to solidify the mixture by curing the epoxy resin portion by adding a curing agent to the slurry after dispersion. By such methods it is also possible to improve the physical properties of the particles, in particular their brittleness, melting point, softening point and even adhesive strength.

If the compound for spheroidization is solid at room temperature,
During dispersion, it is necessary to achieve liquefaction by adopting a temperature condition higher than the melting point (softening point) of the compound, or by dissolving the compound in a solvent.

In the former, by cooling after dispersing in a dispersion medium,
Dispersed particles can be solidified. In the latter case, after being dispersed in a dispersion medium, the dispersed particles can be solidified by stirring at a temperature near or above the boiling point of the solvent, or by evaporating the solvent under reduced pressure. Even in this case, it is possible to blend and cure components such as polyester resins and epoxy resins as described above in order to improve the physical properties of the particles.

In the above-mentioned emulsion method, when the compound or compound for spheroidization is insoluble in water or dissolved in a water-insoluble solvent, it is common to disperse it in water. be. As a dispersion method, well-known emulsification techniques can be used. An example of this is as follows: a method in which an anionic, nonionic, or cationic surfactant is added in an amount of 1 to 20% by weight based on the weight of the material to be emulsified, and the material to be emulsified and the dispersion medium are vigorously stirred. be. The surfactant may be added to either or both of the emulsifier and the dispersion medium. Instead of a surfactant, use a polymeric protective colloidal compound such as polyvinyl alcohol or hydroxypropyl cellulose at 0.0%.
There is also a method in which a compound for spheroidization is dispersed in water in which 5 to 20% by weight is dissolved.

Although not intended to limit the present invention, a compound for spheroidization or a mixture thereof is dissolved in a solvent with a low boiling point due to water, such as benzene or chloroform, and polyvinyl alcohol is added to it while stirring vigorously. An example of a preferred dispersion method is a method in which water in which a protective colloidal compound is dissolved is gradually added to prepare an O/W emulsion via a W10 emulsion. The solvent can be removed from this emulsion by heating, stirring, depressurization, or the like. Further, when the epoxy resins are mixed in a compatible manner, it is also possible to cure the emulsion by adding water-soluble amines to the emulsion.

When the compound for spheroidization or a mixture thereof is dissolved in a water-soluble solvent such as dimethylformamide or ethyl alcohol, a dispersion medium that does not show solubility therein, such as liquid paraffin, is used. A common method is to disperse it in a liquid.

It is preferable that the spherical particles contain a curing catalyst or a curing accelerator inside the particles, if necessary. The curing catalyst preferably used in the present invention is preferably a peroxide such as benzoyl peroxide, methyl ethyl ketone peroxide, or cumene hydroperoxide, or an oil-soluble initiator such as azobisisobutyronitrile. Examples include cobalt naphthenate, cobalt octenoate, dimethylaniline, and acetylacetone. These are added to the compound for spheroidization, or a mixture thereof, or a solution thereof, and are preferably present therein in a compatible state, and are integrally emulsified and incorporated into the particles. Most recommended. However, a similar effect can be expected by adding a curing catalyst, a curing accelerator, or an emulsion of a solution thereof to a slurry of particles after spheroidization and allowing the particles to absorb it.

In addition to curing catalysts and curing accelerators, spheroidized particles contain amine compounds that can crosslink with ethylenic double bonds, such as p°-diaminodiphenylmethane, and inorganic compounds such as silica. Fillers, dyes, and pigments may be included, and can be added to the particles in the same manner as the curing catalysts and curing accelerators described above.

In addition, fine sol or powder of 0.1 μm or smaller silica or alumina may be mixed with the particles after spheroidization, either as a slurry in one stage or as a powder after filtration and drying, or they may be adsorbed onto the surface. By doing so, blocking properties, fluidity, and charging properties can be improved.

Separate the spherical particles prepared as above from the dispersion medium,
The hot melt thermosetting powder obtained by drying preferably has an average particle size in the range of 0.5 to 500 μm, more preferably 1 to 300 μm. When the average particle diameter is smaller than this, it is difficult to recover the spherical particles from the dispersion medium, and when it is larger than this, it is not suitable for bonding fine parts.

One of the preferred uses of the above powder is to adhere narrow gaps in the form of dots, in which case the average particle size is 1 to 5.
It is preferably 0 μm, more preferably 2 to 30 μm, and the particle size variation rate (standard deviation of particle size distribution divided by average particle size and multiplied by 100) is 30% or less, more preferably 20% or less. It is preferable that A typical example of such uses is point adhesion of liquid crystal display elements. In this application, since the adhesive is adhered in dots within the image, if large particles are mixed in, they will be visible to the naked eye, causing a reduction in image quality. In addition, small particles do not reach the side substrate and therefore do not contribute to adhesion.

The powder adhesive of the present invention can be used not only for displays but also for liquid crystal shutters, liquid crystal projectors, etc. in relation to liquid crystal elements. Other uses include adhesion of glass, metal, and ceramic materials, adhesion and sealing of electronic materials such as IC sealants,
It can be added to plastics to modify them, and can also be used as toner for electronic copying machines.

[Example] The present invention will be further described below with reference to Examples, but the present invention is not limited thereto.

Example 1 3.3′-dimethyldiphenylmethane bismaleimide (
0.1 g of tertiary butyl perbenzoate was dissolved in 10 g of a chloroform solution in which 15% by weight of Mitsui Toatsu, BM IT) was dissolved. Put it in a 100CC poly cup,
Stirrer with Teflon plate blades at the tip 800 r
Polyvinyl alcohol EG-05 while stirring to pm
(Nippon Gosei Kagaku) 8g of 8g aqueous solution was added four times at 1 minute intervals to emulsify the chloroform solution.

Furthermore, add 10g of water to dilute, and then mix the whole (10℃
The temperature was raised to , and chloroform was evaporated from the particles while stirring gently.

After the bubbles on the surface of the emulsion due to evaporation of chloroform stopped and the chloroform odor disappeared, the particles were washed temporarily and air-dried. A spherical particle powder with an average particle diameter of 18 μm was obtained. A small amount of this powder is sandwiched between two glass plates whose surfaces are coated with polyimide.
It was placed in an oven at 190° C. while being held down with a clip, and processed for 2 hours. After cooling, the glass plate is firmly bonded.
I couldn't peel it off.

Example 2 3,3°-dimethyldiphenylmethane bismaleimide 4. Og and 6.0 g of Epicote 828 (oiled shell epoxy, epoxy equivalent 190), which is a bisphenol A-based diglycidyl ether, were
Dissolved in 0 g of chloroform. Furthermore, after dissolving 0.2 g of dicumyl peroxide, a polyvinyl alcohol solution was added and the whole was emulsified in the same manner as in Example 1. In addition to the emulsion, polyvinyl alcohol EG0
After adding 20g of 8% by weight aqueous solution of No. 5, the whole was (1
The temperature was raised to 0° C., and chloroform was completely volatilized from the particles while stirring gently.

After cooling, 0.3 g of hydrated hydrazine was added, and the epoxy resin portion was partially cured at 20° C. for one week with gentle stirring.

After repeating the process of "ultrasonic cleaning - once redispersing in water" four times, it was finally redispersed in water. Average particle size 12μm
Spherical particles were obtained, and the particle size was adjusted to an average particle size of 10 μm and a particle size variation rate of 12% by combining water sieve classification and sieve classification.

Example 3 10 g of an unsaturated polyester resin of terephthalic acid/propylene glycol/maleic acid = 1/2/1 (mole ratio) with a molecular weight of about 15,000 was placed in a 300 cc polycup, dissolved in 40 g of chloroform, and then dissolved in polyvinyl alcohol EG-05. Emulsification was carried out in the same manner as in Example 1 using an 8% by weight solution of and further diluted.

The whole was heated to 10° C., filtered, washed, and air-dried while stirring gently to completely volatilize chloroform. The average particle diameter of the obtained particles was 30 μm.

When the glass plate was cured for 2 hours in an oven at 150°C in the same manner as in Example 1, the glass plate was firmly adhered and could not be peeled off.

Example 4 Unsaturated polyester resin Log with a molecular weight of about 1 (1000 bisphenol A diglycidyl ether/maleic acid = 1/1 (mole ratio)) was placed in a 300CC polycup, and
40 g of chloroform and 0.4 g of dicumyl peroxide
It dissolved together with g. Emulsify in the same manner as in Example 3,
The chloroform was evaporated. After washing in the same manner as in Example 2, the particles were finally redispersed in water, and the particles with an average particle size of 15 μm were divided into particles with an average particle size of 12 μm and a particle size variation rate of 18 by a combination of water-based classification and sieve classification. % particles.

Example 5 6 g of bisphenol F diglycidyl ether/maleic acid = 1/1 (mole ratio) having a molecular weight of about 3500 and 4 g of Epicoat 828 were placed in a 100 cc polycup, and 20 g of methylene chloride and 0.2 g of dicumyl peroxide were added and dissolved. Emulsify with a 4% by weight aqueous solution of polyvinyl alcohol EG-05 in the same manner as in Example 1, further dilute with 10 g of water, heat the whole to 40 ° C., and volatilize methylene chloride from the particles while stirring gently. Ta.

After cooling, 0.2 g of hydrated hydrazine was added, and the epoxy resin was partially cured over one week while being gently stirred.

In the same manner as in Example 2, after washing the particles, the particles are classified using water and sieve, and the particles with an average particle size of 15 μm are adjusted to particles with an average particle size of 10 μm and a particle size variation rate of 22%.

Example 6 Bisphenol A with 1 mole of ethylene glycol added to both ends/tolylene diisocyanate = 2/
1 (molar ratio) of a reactant, 4 g of oligoacrylate in which acrylic acid was ester-bonded to both terminal OH groups, and 8286 g of Ebico were dissolved in 10 g of methylene chloride and 0.2 g of dicumyl peroxide. Emulsification and volatilization of methylene chloride were carried out in the same manner as in Example 5.

After cooling, 0.3 g of hydrazine hydrate was added, and the epoxy resin was partially cured over one week while being gently stirred.

The particles were classified in the same manner as in Example 5 to obtain powder having an average particle diameter of 10 μm and a particle size variation rate of 12% from particles having an average particle diameter of 18 μm.

Example 7 5 g of propylene oxide, epichlorohydrin-modified bisphenol A dimethacrylate (Kyoeisha Yushi Evolite 3002M), 5 g of Epicote 10 (11 <oiled shell epoxy, epoxy equivalent 475), which is a bisphenol A-based diglycidyl ether, and tertiary butyl peroxide. 0.3 g of benzony) was placed in a 100 cc polycup and dissolved in 10 g of chloroform. Emulsification was carried out in the same manner as in Example 1 using a 4% by weight aqueous solution of polyvinyl alcohol EG-05. After further adding Log of water, the temperature was raised to 10℃ and chloroform was volatilized from the particles with gentle stirring.
Nippon epoxy resin was partially cured.

After thoroughly passing through and washing the particles, the particles were subjected to water brine classification and sieve classification to obtain particles with an average particle size of 20 μm to uniform particles with an average particle size of 12 μm and a particle size variation rate of 15%.

Example 8 Epicote 1004, a bisphenol A-based diglycidyl ether (oiled shell epoxy, epoxy equivalent 9
10 g of oligoacrylate having methacrylic acid added to both ends of 25) and 0.05 g of dicumyl peroxide were dissolved in chloroform Log. Furthermore, crystalline cellulose Avicel RC-591 (Asahi Kasei>Ig) was added as a powder emulsifier and well dispersed.

Emulsification was carried out in the same manner as in Example 1 using a 2% by weight aqueous solution of polyvinyl alcohol EG-05, followed by EG-05.
-058% by weight aqueous solution Log was added to dilute.

The temperature was raised to 50°C, and the chloroform was volatilized with gentle stirring, and finally the temperature was raised to 65°C to complete the volatilization.

The obtained particles had an average particle diameter of approximately 200 μm, and when the dry powder was sandwiched between slide glasses and the adhesive force was examined after treatment at 130° C. for 2 hours, it was found that they were firmly adhered.

Example 9 Average particle size is 10-12 μm, particle size variation rate is 12-2
Each of the 2% powder adhesives of Examples 2, 4, 5, and 6.7 was evaluated as follows.

An alignment film consisting of a transparent electrode film and a rubbed polyimide film was formed on the surface, and 10 particles of the above powder adhesive were placed on one side of two glass substrates for liquid crystal display cells of 6 sizes.
As a spacer, about 1000 pieces/cnf of crushed glass fiber particles having a particle diameter of 6±0.2 μm and about 00 pieces/clf were sprinkled.

After applying an epoxy resin adhesive to the periphery of the surface of the glass substrate, the two sheets were stacked together, and only the powder of Example 2 was coated with 180 ml of powder.
The other powders were pressed at 140°C for 2 hours to obtain a cell structure in which the powder adhesive and the peripheral portion were thermoset.

When this cell structure was filled with TN liquid crystal and operated with electricity, good alignment images were obtained for all powder adhesives. The obtained liquid crystal display cell has strong point adhesion within the image, so it is resistant to impact and does not operate stably for a long period of time.

[Effects of the Invention] The powder according to the present invention is suitably used as a point adhesive element for liquid crystal devices such as TN liquid crystal, SBE liquid crystal, and ferroelectric liquid crystal, and provides high adhesive strength, good operability, and long-term stability. . Since the particle size is small, it is not noticeable in an image, and a high-performance and high-quality liquid crystal element can be provided.

Further, the powder adhesive of the present invention can be manufactured with a relatively simple method and can be manufactured at low cost.

Claims (11)

[Claims] (1) The particles have an average particle diameter of 0.5 to 500 μm, are substantially spherical, have at least a component having an ethylenic double bond in the particles, and are of a hot melt thermosetting type. A powder adhesive characterized by: (2) The powder adhesive according to claim (1), wherein the component having an ethylenic double bond is a polyfunctional maleimide. (3) Claim (1) characterized in that the component having an ethylenic double bond is an unsaturated polyester.
Powder adhesive as described in section. (4) The powder adhesive according to claim (1), wherein the component having an ethylenic double bond is a polyfunctional oligoacrylate. (5) The powder adhesive according to claim (3), wherein the unsaturated polyester is bisphenol-based. (6) The powder adhesive according to claim (4), wherein the polyfunctional oligoacrylate is bisphenol-based. (7) The powder adhesive according to claim (1), wherein the component having an ethylenic double bond contains an epoxy resin. (8) The powder adhesive according to claim (7), wherein the epoxy resin is bisphenol-based. (9) The powder adhesive according to claim (1), which has an average particle diameter of 1 to 50 μm. (10) The powder adhesive according to claim (1), wherein the particles have a particle size variation rate of 30% or less. (11) A powder adhesive having an average particle size of 1 to 50 μm, a spherical shape with a particle size variation rate of within 30%, and at least a component having an ethylenic double bond in the particles. , a powder adhesive for liquid crystal elements, characterized in that it is used as a point adhesive for liquid crystal elements.