JPH01197586A - Production of colored powdery adhesive - Google Patents

Abstract

PURPOSE:To obtain a colored powdery adhesive having a high adhesive force and not undergoing bleeding of dye, by introducing a dye having amino groups as dye sites into epoxy resin particles and then introducing amino groups into the particles in coloring epoxy resin particles with said dye. CONSTITUTION:In coloring epoxy resin particles (e.g., bisphenol A epoxy resin) with a dye having amino groups as dye sites (e.g., an acid dye having a carboxyl or sulfo group in the molecule or an azo dye metallized with, e.g., Cr), said dye is first introduced into said epoxy resin particles and then amino groups are introduced into the particles. According to this process, a colored epoxy resin powdery adhesive having a strong adhesive force and not undergoing bleeding of dye can be obtained. These particles can be particularly desirably used as a spot adhesive for liquid crystal elements such as liquid crystal display cells, and light-intensity varying glass, and can improve their impact resistance and long-term stability markedly without detriment to their image quality.

Description

[Detailed description of the invention] [Industrial application field].

The present invention relates to a method for coloring an epoxy powder adhesive.

The colored powder adhesive of the present invention is particularly suitable for use as a spot adhesive for liquid crystal devices.

[Prior Art] Regarding point adhesives for liquid crystal elements, the present inventor has proposed
No. 1-219274@ proposed a thermosetting material whose main component is epoxy resin.

One of the problems when using such a dot adhesive when dot-bonding a liquid crystal element is that its presence is conspicuous within the screen. Particularly in types that use a backlight to achieve high contrast, the adhesive spots tend to scatter polarized light and become bright spots. In dark areas, their presence is emphasized, just like stars in the night sky, and image quality inevitably deteriorates.

As a countermeasure to this problem, it has been considered to reduce the light transmittance of the point adhesive particles, that is, to color the particles. An example of such a known example is Japanese Patent Application Laid-Open No. 61-69839,
Colored epoxy spherical fine particles cured with an amine curing agent and colored with a dye have been proposed.

[Problems to be Solved by the Invention] However, in this known technique, the particles are hardened by heating during dyeing, and the heat meltability and adhesive strength are already reduced before use, making it difficult to use as a point adhesive for liquid crystal elements. It was insufficient for use.

Another method is to color the material using a raw material containing an oil-soluble dye dissolved therein, but the dye seeps into the liquid crystal or a fluorocarbon-based dispersion medium such as Freon 113 used when spraying spot adhesive onto the substrate. There is a problem that comes up.

An object of the present invention is to provide a method for producing a colored powder adhesive that has high adhesive strength and does not ooze out dye.

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

When coloring epoxy resin particles with a dye that uses an amine group as a dyeing site, the dye is introduced into the particle, an amino group is introduced into the particle, or a dye and an amino group are simultaneously introduced into the particle. A method for producing a colored powder adhesive characterized by: (1) dyeing the amine groups within the particles with a dye;
Prevents dye from seeping into fluorocarbon-based dispersion media and liquid crystals.

(2) However, since the amino group hardens the epoxy resin, if the amino group is introduced first, a hardening reaction will occur due to the heating during dyeing, and the adhesive strength of the particles will decrease significantly. For this purpose, the dye is introduced into the particles when there are no amino groups yet, or the amino groups and the dye are introduced simultaneously.

That is what it is.

Detailed explanation of the present invention The epoxy compounds (resins) used in the present invention include:
Those containing two or more epoxy groups in the molecule are preferred. For example, bisphenol A, B
, F, S, H and its condensed dicrycidyl ether,
Neopentyl glycol dicrycidyl ether, 1,6
-Hexane diglycidyl ether, polyethylene glycol diglycidyl ether, alicyclic epoxy resin, etc. Among those having three or more epoxy groups,
There are polyglycidyl ethers of phenol novolac type compounds and N,N,N',N-tetraglycidyl m-xylene diamines, which can be used alone or in combination. It is also possible to use a compound having one epoxy group in the molecule, for example, 2-ethylhexyl glycidyl ether, if necessary.

It is preferable to add a latent curing agent to the epoxy compound before micronizing the epoxy compound and making it into a powder adhesive.

Examples of latent curing agents include dicyandiamide,
Imidazoles, Lewis acid complexes, phenols, bisphenols, phenol novolacs, polyvinylphenols, carboxylic acids, acid anhydrides, acidic polyesters, styrene maleic acid copolymers, etc., polymers containing oleboxyl groups, hydrazides, polyamines, There are modified polyamines.

Combinations of the epoxy compound and the latent curing agent exhibiting at least partial compatibility, preferably complete compatibility, are preferably used in the present invention.

The latent curing agent is usually preferably 0.05 to 1 epoxy group per epoxy group of the epoxy compound, but as described later, an amine curing agent can be used to form emulsions and suspension particles of the epoxy compound. When partially curing (B-staged), the optimum value may be considerably smaller.

When a catalytic latent curing agent is used, it is used in an amount of approximately 20% or less based on the weight of the epoxy compound.

The dye having an amino group as a dyeing site used in the present invention is
It forms an ionic bond with an amino group, and includes acid dyes and metal complex azo dyes such as Or, which have a carboxyl group or a sulfone group in the molecule. The carboxyl group and sulfone group in the dye may be neutralized with an alkali metal or the like or not.

The most preferred dye for achieving the present invention is one that is easily soluble in ethyl alcohol, or in other words, one that is both water-soluble and oil-soluble. Dyes with many sulfonic groups tend to be less oil-soluble. However, even with such a dye, it is possible to color the particles in a light color according to the present invention.

Next, a method for coloring particles with the above dye and a method for preparing particles will be described in detail.

First, regarding the pulverization of epoxy compounds, if the epoxy compound is a non-adhesive solid at around room temperature, there is a method of mechanically pulverizing it by means such as freeze pulverization (mechanical pulverization method).
. However, since this method results in irregularly shaped particles, there is a method in which the pulverized particles are made spherical by floating in a hot section or falling by gravity (the first method).
.

Another method is to suspend (emulsion or suspension) an epoxy compound in a water-based liquid to form spheres (this is the second method).

In the present invention, the above-described first method and second method are not particularly limited, but the second method is particularly preferred from the viewpoint of particle uniformity, sphericity, etc.

A typical example belonging to the second method is shown below.

■ A method in which the epoxy compound or its solution is continuously discharged from a nozzle that vibrates in the air or in the liquid, cutting it into droplets and collecting it in the liquid.

■ A method in which an epoxy compound or its solution is ejected in pulses from a nozzle in the air or in a liquid, and then collected in the liquid.

■ A method of emulsifying an epoxy compound using a surfactant.

■ A method of emulsifying an epoxy compound using a powder emulsifier.

■ A method of emulsifying epoxy compounds with water containing protective colloidal substances. □ Among the above methods, methods 1 to 2 are preferably used in the present invention from the viewpoint of productivity, but a combination of methods 1 to 2 is also preferably used in the present invention.

In addition, the surfactant used in the above method is not particularly limited, but examples include ether type nonionic interfaces such as polyoxyethylene/phenol substituted ether type, polyoxyethylene/polyoxypropylene block/polyether type, etc. Typical active agents include ester-type nonionic surfactants such as higher fatty acid esters of polyethylene glycol and fatty acid esters of polyhydric alcohols, and nonionic surfactants such as alkoxylated rosins.

The surfactant is added in an amount of about 2 to 30 wt % to a mixture (resin mixture) of an epoxy compound, an accelerator rubber component, and if necessary a latent curing agent, or a solution thereof. Powder emulsifiers include finely powdered crystalline cellulose and barium sulfate powder.
About t% is used. Further, protective colloidal substances include polyvinyl alcohol chillulose, gelatin, sodium alginate, etc., and are generally used after being dissolved in water at about 0.5 to 20 wt%.

The method of introducing dye into particles will be described in sequence.

First, there is a method in which a dye is blended in advance into a resin mixture that serves as a raw material. Since the dye used in the present invention has a slow rate of dissolution into the resin mixture within the membrane, it is usually mixed into the resin mixture after being dissolved in a common solvent for both dyes. The amount of dye added is preferably about 1 to 15 wt% of the resin mixture, and if it is less than 1 wt%, the coloring effect will be low;
When the amount exceeds %, the dye tends to seep out from the particles.

As the solvent used in the present invention, a solvent having a boiling point lower than that of water and having low solubility in water is preferable in relation to subsequent steps (emulsification and desolvation). Examples include chloroform, methylene chloride, carbon tetrachloride, ethyl needles, ethyl acetate, and benzene. Note that there is no problem even if these organic solvents contain about 5 Qwt% of a water-soluble organic solvent such as methanol, ethanol, or acetone.

In the mechanical grinding method, it is preferable to grind the mixture of the resin mixture, dye and solvent from which the solvent has been removed, and in the first method to obtain spherical particles, the solvent is removed while passing through a heating cylinder. It is also possible.

In the second method for obtaining spherical particles, the solvent can be removed by heating or reducing pressure from the suspension.

Another method for introducing the dye is to add the above-mentioned dye to an aqueous suspension of particles, with or without a solvent, and, if necessary, to dye the particles by heating to 60 to 98°C. As for dye presentation, 1wt to 15w to the resin mixture.
Although approximately t% is added within the membrane, even if the amount is increased, the dye will not be dyed onto the particles, so this will not pose an essential problem in achieving the present invention.

This method is common to the first method and the second method for forming particles, and in the first method, the obtained particles are dispersed in water and applied.

In the above method, when a solvent is included, dyeing is generally carried out after solvent removal, but dyeing and solvent removal can also be carried out simultaneously. If the particles contain a solvent,
In cases where the softening point is low and fusion bonding is performed at the dyeing temperature,
In both the dyeing and solvent removal processes, if the aforementioned protective colloidal substance such as polyvinyl alcohol or gum arabic is dissolved in water, growth and coarsening due to bonding of particles can be prevented. This method can also be applied when removing the solvent when a resin mixture pre-mixed with a dye is used as a raw material.

Next, we will discuss how to introduce amine groups into particles.

If the dye is pre-blended in the resin mixture, the same u
Sea urchin amine compounds such as piperazine, hydrazine, ethylenediamine, diethylenetriamine, triethylenetetramine and other polyethylene polyamines, monoethanolamine and other alcohol amines, N(2-aminoethyl)piperazine, diaminodiphenylmethane, diaminodiphenyl sulfone, adipic acid dihydrazide ,
It may also contain polyamide polyamine and the like. Among these, those that serve as room-temperature curing agents for epoxy compounds are particularly preferably difunctional ones such as piperazine and hydrazine, which are used in an amount of about 0.1 to 1 mole relative to the epoxy compound, and are used at room temperature to 40'C. The mixture is introduced over a period of one day or more while being allowed to stand still or with gentle stirring.

On the other hand, in the case of a heat curing type (latent type curing agent) such as diaminodiphenylmethane, approximately 1 equivalent is used. This difference in the amount used is determined by the thermal fusing properties and adhesive strength of the particles.
For example, if one equivalent is used, particles with poor thermal meltability will be obtained.

However, when the dye forms a neutralized product with an amine as a carboxylic acid or sulfonic acid, the inherent curing effect of the amine compound may be reduced, so the amount of the amine compound to be used in such a case should be the same as above. be greater than the amount of

Furthermore, when using an amine compound that cures at room temperature, the desolvation temperature should be kept low, and conditions around room temperature using a vacuum desolvation method are preferred. Also, the first method for obtaining spherical particles cannot usually be used.

In contrast, a method for introducing amino groups into particles when dyeing is carried out by adding a dye to an aqueous suspension of particles will be described.

(This method can also be applied when the aforementioned dyes are pre-blended in the resin mixture.

In this case, water-soluble amine compounds such as piperazine, hydrazine,
Ethylenediamine, diethylenetriamine, triethylenetetramine, etc. ．． Add approximately 0.1 to 2 ethylene polyamines, alcohol amines such as monoethanolamine, N(2-aminoethyl>piperazine, etc.).
It is preferable to add it to the aqueous suspension after cooling it to room temperature to about 40'C, but even during dyeing, it is possible to add the dye and the amine compound 9 simultaneously for a short time of about 1 hour. It is. In addition, the introduction of the amine compound into the particles
The purpose is to form a dyeing seat (amino group) and to B-stage the epoxy compound.
This is achieved by standing at about 0°C or under gentle stirring for over a day.

Any of the above-mentioned powdering methods for epoxy compounds,
In any dye introduction method or any amino group introduction method, it is preferable that 7JO of the latent curing agent of the epoxy compound is obtained, as described above. However, it goes without saying that latent curing agents that cause curing under heating conditions during solvent removal or dye introduction are not preferred.

Latent curing agents commonly preferably used in the present invention are:
Phenolic curing agents such as phenol novolacs, polyvinylphenols, diglycidyl ethers of bisphenols or their condensates, and polyhydric phenol compounds have high adhesive strength and good storage stability at room temperature.

Other additives may be included in the present invention. The most typical additive is a rubber component added to give particles low-temperature flexibility, and includes rubbers and acrylic rubbers that use at least butadiene as one of the copolymer components. Thermosetting resin component (mixture of epoxy compound and curing agent>30 to 95 wt%, rubber component 5 to
It is preferable to add it at a blending ratio of about 7Qwt%. In many cases, the rubber component is phase-separated from the thermosetting resin component in a sea-island pattern within the particles. Further, fine powder with a sharp particle size distribution, such as crushed glass fibers, glass beads, alumina spheres, and crosslinked polystyrene spheres, may be similarly included, and adhesive fine particles containing spacers can be obtained by this method. Also, 0.5μ such as silica sol and alumina sol
It is also possible to mix or dye about 0.05 to 5 wt % of ultrafine particles with a particle diameter of 0.0 m or less to prevent blocking or charging of the particles after drying.

The particle size of the particles of the present invention is preferably in the range of 0.1 to 500 μm, more preferably 0.5 to 200 μm.

It is substantially difficult to prepare particles with a particle size of less than 0.1 μm, and the function as an adhesive deteriorates. on the other hand,
If the particle size exceeds 500 μm, the particle size is too large for use as a powder adhesive or for powder coating, which poses a practical problem.

When the particles obtained in the present invention are used as a point adhesive for liquid crystal elements, the average particle diameter is preferably in the range of 1 to 100 μm, more preferably in the range of 1.5 to 60 μm. In these ranges, the lower limit value is naturally determined by the lower limit of the substrate gap that can be realized in the liquid crystal element.

On the other hand, the upper limit of the average particle diameter is related to the lower limit of the size at which the presence of particles can be significantly detected with the naked eye in actual usage conditions, and if the particle size is larger than this, the quality of the liquid crystal element will be significantly impaired.

In addition, when used as a liquid crystal element, the particle size fluctuation rate is
It is preferably within 30%, more preferably within 20%. Fine particles will not reach between the rain plates and will only adhere to one side, making them unnecessary particles that do not contribute to the adhesive force at all. Large particles will stand out and reduce the quality of the liquid crystal element, so make sure to keep them as sharp as possible. It is generally preferred to have a distribution.

Note that the particle size variation rate refers to the value obtained by dividing the standard deviation (α) of the particle size distribution by the average particle size and multiplying the result by 100.

[Example] Example 1 Epicote 828, a bisphenol A-based diglycidyl ether (oiled shell epoxy, epoxy equivalent 19
0) and Epicote 1001 (oil-based oil epoxy, -
5 g each of epoxy equivalent (475) and 1.5 q of phenolic latent curing agent Epicure 171N (oil-based shell epoxy, phenolic OH equivalent maximum 220) were placed in a 100 CC polyethylene cup, and quickly melted and kneaded at 95°C to form a uniform mixture. Made into a compatibilist. Heat the container to 50°C from the surrounding area to lower the viscosity, and add 4wt of polyvinyl alcohol Gohsenol EGO5 (Nippon Gosei Kagaku, polymerization degree of about 500>
% aqueous solution at 1.5cc each, 4 times at 1 minute intervals, total 6c
c was added to the above compatible solution and emulsified. To the colander, 5 cc of Gohsenol EGO 54 wt % aqueous solution and 6 cc of water were added to dilute.

Karan Black 2RL, a metal complex azo dye (
Purified product of Nippon Herbal Medicine, CI Acid Black 155) (temporarily removed insoluble matter in acetone, deacetonized) > 0.4 CI was added, and 80
The temperature was raised to 0.degree. C., and the dyeing process was continued for 30 minutes.

After cooling to room temperature, 10 g of hydrated hydrazine was added and left at room temperature for 10 days with gentle stirring to introduce amino groups into the particles and B-stage them.

The particles were filtered and the utilization rate of the dye was determined from the absorbance of the filtrate (dye dyed on the particles/dye used for dyeing x1QQwt
%) was 75%, and 49 spherical black particles with an average particle diameter of 11 μm were obtained.

Sandwich the air-dried particle size 5mc+ between two glass slides,
When it was fixed with a clip and heat-treated in a hot air dryer at 130° C. for 30 minutes, it melted into a black transparent film. In addition, the splitting strength against glass pieces was measured according to JIS K6853 (0.5 ma sample was 15 mm x 15 m
50k (value measured by curing the material sprayed on the substrate at 180° C. for 2 hours) is 50k (1/15 mm).

On the other hand, 100 mg of each of the above particles were placed in two 10CC sample tubes, and one was filled with 6 g of Freon 113 (Mitsui DuPont Fluorochemical > 96 wt%/4 wt% ethanol mixed solution).
and 6 g of TN liquid crystal ZLI-1565 (Merck Japan) was added to the other side and left for 40 days, but no dye seepage was observed from either side.

Comparative Example 1 In Example 1, 1 q of hydrazine was added and gently stirred at room temperature for 10 days to introduce amine groups into the particles and B-staging them without performing the dyeing treatment after emulsification. The 1q particles were spherical and white in color and had an average particle diameter of 10 μm.

After redispersing the particles in 18 g of water, 0.4 g of Kayakaran Black 2RL purified product used in Example 1 was added, and dyeing was carried out at 70° C. for 20 minutes with stirring. The various properties obtained in the same manner as in Example 1 are as follows.

The dye utilization rate was 4 Qwt%, the heat meltability did not form into a film at 130°C, and the splitting strength was 10 km and 15 mm.

Comparative Example 2 The 8-staged particles before dyeing obtained in the same manner as Comparative Example 1 were redispersed in 18 g of water, and then 0°40 of Kayakaran Black 2RL purified product used in Example 1 was added. The dyeing process was carried out by gently stirring at room temperature for 10 days.

The properties obtained in the same manner as in Example 1 are as follows.

The dye utilization rate was 1% or less, the heat meltability was formed into a film at 130° C., and the splitting strength was 60 ko/15 mm.

Example 2 Epicoat 828 5C11 engineered Picoat 10015g,
1.5 g of Epicure 171N, 0.4 C of Kayakaran Black 2RL purified product] and 0.8 g of piperazine were dissolved in chloroform 10Q.

Emulsification and dilution were performed in the same manner as in Example 1 except that the temperature was room temperature.

Chloroform was evaporated from the particles under reduced pressure while stirring gently at room temperature.

Further, the mixture was left at room temperature for 6 days with gentle stirring to perform B-stage formation, thereby obtaining spherical black particles with an average particle diameter of 8 μm.

The properties of the particles determined in the same manner as in Example 1 are as follows.

Dyeing 1'l utilization rate is 60%, heat meltability is filmed at 130℃, splitting strength is 65kmM15mm, Freon 113 9
6wt%/ethanol 4wt% mixture and TN liquid crystal Z
There was no dye bleed for LI-1565.

Example 3 Instead of the dye Kayakaran Black 2 RLM product, Red 1, which is an acid dye with sodium carboxylate as the dyeing polar group, was used.
Using 0.6q of No. 04 (Phloxine B), 1q of red spherical particles with an average particle diameter of 12 μm were prepared in the same manner as in Example 1. This dye 1 dissolves well in ethanol.

The properties of the particles determined in the same manner as in Example 1 are as follows.

Dye utilization rate is 60%, heat meltability is made into a film at 130'C, splitting strength is 50km/15mm, Freon 113 9
6wt%/ethanol 4W↑% mixed liquid and TN liquid crystal Z
There was no dye bleed for LI-1565.

[Effects of the Invention] According to the manufacturing method of the present invention, an epoxy resin-based colored powder adhesive with high adhesive strength and no seepage of dye 1 can now be produced.

The adhesive particles of the present invention are particularly suitable for use as point adhesives for liquid crystal devices such as liquid crystal display cells and light control glasses, and can dramatically improve impact resistance and long-term stability without reducing image quality. It is effective for

Claims (2)

[Claims] (1) A method for producing a colored powder adhesive, characterized in that when epoxy resin particles are colored with a dye that uses amino groups as dyeing sites, the dye is introduced into the epoxy particles, and then the amino groups are introduced. (2) A method for producing a colored powder adhesive, which comprises simultaneously introducing a dye and an amino group into the epoxy resin particles when coloring the epoxy resin particles with a dye that uses amino groups as dyeing sites.