JPH0773669B2 - Microcapsules containing diazonium salt and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a method for producing microcapsules containing a diazonium salt used in a novel heat-developable copying material. More specifically, the present invention relates to a method for producing a microcapsule having a wall film made of a polymer substance and having substantially no solvent in the capsule of 0.3 μ to 12 μ.

<Prior Art> A number of methods are known as methods for producing microcapsules containing a hydrophobic liquid. The enumeration is as follows.

Phase separation method from aqueous solution (US Pat. Nos. 2900457 and 2900)
No. 800458), which is the most common and practical one and utilizes coacervation of hydrophilic colloid sol.

Interfacial polymerization method (JP-B-38-19574, JP-B-42-446,
Japanese Examined Patent Publication No. 42-771, British Patent Nos. 989264, 950443
No., No. 867797, No. 1069140, No. 1046409)
The first wall film is prepared by allowing a monomer or an initial condensate, which is a first wall film-forming substance, to exist in an oily liquid to be incorporated without using a polymer that has been completed as a wall film substance of a microcapsule. Second having a group capable of reacting with a forming substance
Is dissolved in a polar solvent immiscible with the oily liquid, and the first wall film forming substance and the second wall film forming substance are polymerized at the interface between the oil droplets of the oily liquid and the polar solvent. Form a wall membrane.

Method by polymerization of monomer in oil droplets (Japanese Patent Publication No. 36-91)
No. 68), an acrylic compound, a compound having a double bond such as styrene and vinyl acetate is dissolved in an oil droplet, and a peracid compound is used as a catalyst to advance radical polymerization to obtain an oil-insoluble polymer. To generate.

Melting dispersion cooling method (UK Patent Nos. 952807 and 965074)
Then, a stable substance that is solid at room temperature and liquid when heated is used as a microcapsule wall film. Wax or thermoplastic resin is used.

Spray drying method (U.S. Pat. No. 3111407, British Patent No. 930422), which applies the principle of spray drying, in which solid particles or liquid emulsified and dispersed in a polymer solution is applied to a spray dryer, and the dispersion liquid is obtained from an atomizer. Are flicked out in the form of fine particles, and at that moment, the polymer surrounds the internal substance, and so on.

These methods are complicated in terms of manufacturing method, and in addition to manufacturing problems such as difficult control of capsule size, there is also a problem that the performance of the capsule is largely controlled by the solvent present as the core substance. Have In particular, in the capsule containing a diazonium salt as in the present invention, the property may be hidden by the coexisting solvent even if the characteristics of the diazonium salt are to be extracted.

Therefore, a first object of the present invention is to provide diazonium salt-encapsulating microcapsules that are substantially solvent-free.

It is a second object of the present invention to provide a method for stably producing diazonium salt-encapsulating microcapsules that are substantially free of solvent.

<Means for Solving the Problems> The above object of the present invention is to provide a non-aqueous solvent having a boiling point of 40 ° C. or more and 95 ° C. or less at a normal pressure with a diazonium salt and the same or different species which react with each other to produce a polymeric substance. Disperse and emulsify the solution of the compound in the hydrophilic protective colloidal solution, raise the temperature of the system to move the wall-forming substance to the oil droplet surface, and promote the polymer formation reaction on the oil droplet surface to promote the wall formation. This is achieved by a method for producing a microcapsule containing a diazonium salt in the microcapsule and being substantially free of a solvent, which is characterized in that a film is formed. At this time, it is preferable to distill off the non-aqueous solvent while reducing the pressure in the reaction vessel during the reaction for forming the wall film.

Further, in the above production method, the non-aqueous solvent is preferably a halogenated hydrocarbon or at least one compound selected from fatty acid esters, ketones and ethers, and the polymer substance forming the wall of the microcapsule is polyurethane. It is preferably formed by at least one selected from polyurea.

The nonaqueous solvent having a boiling point of 40 ° C. or higher and 95 ° C. or lower at atmospheric pressure used in the present invention is preferably used in a ratio of 5 to 100 parts by weight with respect to 10 parts by weight of the solute diazonium salt.

Specific examples of the non-aqueous solvent used in the present invention are listed below, but the present invention is not limited thereto.
The value in () indicates the boiling point at normal pressure.

Acetone (56), Isoamyl methyl ether (91), Isopropyl methyl ketone (94) Methyl isobutyrate (92),
Ethyl isobutyl ether (79), ethyl isopropyl ether (54), ethyl propyl ether (64), t-amyl chloride (86), ethylene chloride (84) isobutyl chloride (69), butyl chloride (78), ethylidene chloride (57) ), Propyl chloride (46), methylene chloride (42), ethyl formate (5
4), propyl formate (81), chloromethyl methyl ether (59), methyl chloroformate (71), ethyl acetate (7
7), Methyl acetate (57), Carbon tetrachloride (77), 1,1-Dichloropropane (86), Trichloroethylene (87), Methyl propionate (80), Propyl ether (91), Methyl chloroform (74) ), Chloroform (61) The same or different compounds that react with each other to form a polymer substance forming the wall of the microcapsule used in the present invention are the corresponding monomers when the preferable polymer substance is polyurea or polyurethane. Is selected from the isocyanate compounds shown below. The amount of the monomer used is determined so that the average particle size of the microcapsules is 0.3 μ to 12 μ and the wall thickness is 0.01 μ to 0.3 μ.

Specific examples of the monomer used in the present invention are listed below, but the present invention is not limited thereto.

General formula [1] (N is an integer of 0 to 10) The aromatic isocyanate used in the present invention may be a single product of n = 0,1,2,3, ... It may be a mixture.

Specific examples of the aliphatic polyvalent isocyanate used in the present invention include hexamethylene diisocyanate,
Propylene-1,2-diisocyanate, butylene-1,2-
Diisocyanate, ethylidine diisocyanate, cyclohexylene 1,4-diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and trimethylolpropane adduct, hexamethylene diisocyanate and hexanetriol adduct, hexamethylene diisocyanate biuret, hexamethylene diisocyanate isocyanate Examples include nurate and isocyanurate of isophorone diisocyanate.

For the purpose of changing the physical properties of the walls of the microcapsules, diamines and diols may be allowed to coexist with the above isocyanate to carry out a polymerization reaction.

The diazonium salt used in the present invention mainly refers to an aromatic diazonium salt.

The diazonium salt is a compound represented by the general formula ArN ₂ X. (In the formula, Ar represents a substituted or unsubstituted aromatic ring, N ₂ represents a diazonium group, and X represents an acid anion.) Specific examples of the diazo compound used in the present invention include the following. An example is given.

4-diazo-1-dimethylaminobenzene 4-diazo-2-butoxy-5-chloro-1-dimethylaminobenzene 4-diazo-1-methylbenzylaminobenzene 4-diazo-1-ethylhydroxyethylaminobenzene 4-diazo -1-Diethylamino-3-methoxybenzene 4-diazo-1-morpholinobenzene 4-diazo-1-morpholino-2,5-dibutoxybenzene 4-diazo-1-toluylmercapto-2,5-diethoxybenzene 4- Diazo-1-piperazino-2-methoxy-5-chlorobenzene 4-diazo-1- (N, N-dioctylaminocarbonyl) benzene 4-diazo-1- (4-tert-octylphenoxy) benzene 4-diazo-1 -(2-Ethylhexanoylpiperidino) -2,5-dibutoxybenzene 4-diazo-1- ( 2,5-di-tert-amylphenoxy-α-butanoylpiperidino) benzene 4-diazo-1- (4-methoxy) phenylthio-2,5
-Diethoxybenzene 4-diazo-1- (4-methoxy) benzamide-2,5
-Diethoxybenzene 4-diazo-1-pyrrolidino-2-methoxybenzene Specific examples of the acid forming the diazonium salt with the diazo compound include the following examples.

C _n F _{2n + 1} COOH (n is an integer of 1 to 9) C _m F _{2m + 1} SO ₃ H (m is an integer of 1 to 9) Boron tetrafluoride, tetraphenyl boron hexafluorophosphoric acid, aromatic carvone Acid aromatic sulfonic acid, metal halide (zinc chloride, cadmium chloride, tin chloride)
Etc.) When the microcapsule of the present invention is used in a copying material, it is preferable to include a free radical generator and a vinyl monomer in the microcapsule together with the diazonium salt, if necessary.

Examples of the hydrophilic protective colloid of the present invention include natural or synthetic hydrophilic polymer substances such as gelatin, gum arabic, casein, carboxymethyl cellulose, starch and polyvinyl alcohol. Further, a surfactant may be used for emulsifying and dispersing, for example, alkylbenzene sulfonate, alkylnaphthalene sulfonate, polyoxyethylene sulfate, anionic one such as funnel oil, polyoxyethylene alkyl ether. , Sorbitan fatty acids such as non-ionic ones.

The microcapsule of the present invention has a characteristic that it does not substantially contain a non-aqueous solvent, but the present inventors have investigated the non-aqueous solvent contained in the microcapsule by the following method. Quantitation was developed and defined as "substantially free" of the present invention.

The microcapsule of the present invention is rarely used alone as a capsule liquid, and is generally used by forming a coating liquid together with a coupler and a base, applying the coating liquid, and allowing the coating liquid to be present in a film of a copying material. Therefore, the non-aqueous solvent, which was contained in the capsule liquid at a level of several percent, was below the detection limit in the coating film.

0.1 g of microcapsule liquid produced by the production method of the present invention
Was weighed into a 20 cc volumetric flask, methanol was added to make exactly 20 cc, and the mixture was left for 30 minutes. The above methanol solution (2 cc) was weighed with a microsyringe and injected into a gas chromatograph mass spectrometer (M-80B, Hitachi Ltd.). The column used was TENAX 3 mmφ × 1 m. It quantified using the m / z peak according to the solvent to be measured. (For example, in the case of ethyl acetate, m / z = 43, and in the case of methylene chloride, the peak of 84 was used.) According to this measuring method, the microcapsule solution of the present invention
It contained 0.01 to 3.00% of non-aqueous solvent.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Example 1> 1-morpholino-2,5-dibutoxybenzene-4-diazonium hexafluorophosphate group 3.45 parts and xylylene diisocyanate and trimethylolpropane (3: 1)
18 parts of the adduct was added to 10 parts of ethyl acetate and dissolved by heating.
A solution of this diazonium salt was added to polyvinyl alcohol 5.
Two parts were mixed with an aqueous solution in which 58 parts of water was dissolved and emulsified and dispersed at 20 ° C. to obtain an emulsion having an average particle size of 2.5 μ. 100 parts of water was added to the obtained emulsion, and the mixture was heated to 60 ° C with stirring,
After 2 hours, a capsule liquid containing a diazonium salt as a core substance was obtained. During the reaction, the container was 100 mmHg-1 with a water pump.
It was kept under a reduced pressure of 30 mmHg.

Ethyl acetate in the capsule liquid was quantified by the above-mentioned measuring method to obtain a value of 0.87%.

Example 2 Next, 10 parts of 2-hydroxy-3-naphthoic acid anilide and 10 parts of triphenylguanidine were added to 200 parts of a 5% aqueous solution of polyvinyl alcohol and dispersed in a sand mill for about 24 hours to obtain a dispersion having an average particle size of 3 μm. Got

To 50 parts of the diazonium salt capsule solution obtained in Example 1, 50 parts of a dispersion of a coupling component and triphenylguanidine and 10 parts of a 40% calcium carbonate dispersion were added to prepare a coating solution. This coating solution was applied to a smooth high-quality paper (75 g / m ² ) so as to have a dry weight of 10 g / m ² using a coating bar, and dried at 50 ° C. for 1 minute to prepare a copying material.

When 0.05 m ² of this copying material was immersed in 20 cc of methanol for 1 hour and the extract was measured by the above-mentioned method, the content of ethyl acetate was below the detection limit.

Claims (4)

[Claims] 1. A hydrophilic protective colloid prepared by dissolving a solution of a diazonium salt and the same or different compound that reacts with each other to form a polymeric substance in a non-aqueous solvent having a boiling point of 40 ° C. to 95 ° C. at atmospheric pressure. After being dispersed and emulsified in a solution, the temperature of the system is raised to move the wall forming substance to the oil droplet surface, and the polymer forming reaction is allowed to proceed on the oil droplet surface to form a wall film. 1. A method for producing microcapsules containing a diazonium salt and containing substantially no solvent. 2. The method for producing microcapsules according to claim 1, wherein the non-aqueous solvent is distilled off while reducing the pressure in the reaction vessel during the reaction for forming a wall film, thereby substantially containing no solvent. A method for producing a microcapsule for obtaining a microcapsule. 3. A non-aqueous solution in which a diazonium salt is dissolved,
The method for producing microcapsules according to claim 1, which is at least one compound selected from halogenated hydrocarbons, fatty acid esters, ketones, and ethers. 4. The microcapsules obtained by the method for producing microcapsules according to claim 1, wherein the polymer substance is formed of at least one selected from polyurethane and polyurea. capsule.