JPS60166026A - Preparation of double nuclear dispersion of microcapsule having synthetic polymer wall film - Google Patents

Abstract

PURPOSE:To prepare the titled dispersion having improved pressure responsiveness by reducing the pH of a single nuclear dispersion of microcapsule having synthetic polymer wall film in the presence of an amphoteric polymer electrolyte and an anionic polymer electrolyte, then hardening the film of the wall of the microcapsule. CONSTITUTION:A hydrophobic substance which is immiscible with a polar dispersion medium is dispersed or emulsified in a soln. of a dispersant or an emulsifier in the polar dispersion medium so as to disperse or emulsify said hydrophobic substance to form discontinuous fine particles. Then, synthetic polymer wall film is formed around said fine particles to obtain a hydrophobic material. The single nuclear dispersion of microcapsule having synthetic polymer wall film comprises the hydrophobic material as the core material. The pH of the single nuclear dispersion is reduced in the presence of an amphoteric polymer electrolyte (e.g. gelatin) and an anionic polymer electrolyte (e.g. ethylene/maleic anhydride copolymer). Thus, plural numbers of the single nuclear microcapsule are agglomerated, then, dissociation of the agglomerate is prevented by affecting a hardening agent such as chrome alum. Obtd. double nuclear capsules have improved pressure responsiveness.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method for producing microcapsules. More specifically, the present invention relates to a method for producing a synthetic polymer-walled microcapsule binuclear dispersion particularly suitable for use in producing carbonless pressure-sensitive recording paper. - B, Prior Art Microcapsules are suitable for stably retaining unstable substances (reactive substances, liquid substances, etc.), and are composed of a core substance and a self-containing material formed around the core substance.

There are various methods for producing microcapsules, but representative examples of generally known methods include physical methods, core cell page sealing methods, interfacial polymerization methods, and in-mouth U polymerization methods5. .

As for physical methods, they are suitable for certain uses - medicines - but because the capsule membrane is incomplete, they are insufficient in terms of retaining the contents, so they cannot be used for carbonless paper. It is not possible.

The coacervation method is covered by US Patent No. ZSOO.

457 and 2,800,458, etc., and has been widely used since then, and is used with contents such as colorless dye for carbonless paper, adhesive, liquid crystal, etc.

In this method, the wall film forming materials are usually gelatin, gum arabic, sodium alginate, CMC1 vinyl acetate-maleic anhydride copolymer, vinyl methyl ether, etc.
One or more types selected from anionic substances such as maleic anhydride copolymer and polyacrylic acid are used. The essential drawbacks are that gelatin is used as the main ingredient, so it has poor water resistance and solvent resistance, and is easily tampered with by microorganisms.
Because the coacervation phenomenon occurs only at low concentrations, it is theoretically difficult to create high-concentration capsule emulsions.

On the other hand, methods for producing microcapsules having a synthetic polymer wall include, for example, an interfacial polymerization method and a 1 nsitu polymerization method. Synthetic polymer wall capsules have the characteristics of being resistant to water and solvents and being able to be manufactured in high concentrations, so they have been actively researched in recent years and are being industrialized one after another.In particular, synthetic polymer wall capsules are new in the field of carbonless paper. It is becoming mainstream.

Among them, the interfacial polymerization method uses polyamide, epoxy resin, polyurethane, etc. at the interface between a hydrophobic liquid and a polar dispersion medium.
It produces a film of polyurea, etc., and depending on the film agent, it is possible to create capsules with excellent retention properties (for example, Japanese Patent Publication No. 38-19574, Japanese Patent Publication No. 1957-1972,
446, Special Publication No. 42-771, Special Publication No. 49-451
33, JP-A-55-159990, British Patent No. 1091077, British Patent No. 1091141, etc.).

In addition, an In 5 ltu polymerization method that utilizes an amino resin as a membrane agent has also been put to practical use, and several patents have been filed.

For example, in JP-A-51-9079, ethylene-maleic anhydride copolymer, methyl vinyl ether-maleic anhydride copolymer, polyacrylic acid, etc. are used as system modifiers (emulsifiers), and urea-formalin resin is encapsulated. The styrene-maleic anhydride copolymer is used as a membrane agent in JP-A-54-49984.
No. 51238 uses polystyrene sulfonic acid as an emulsifier and melamine-formalin resin as a capsule membrane material.

In this way, synthetic polymer wall microcapsules have wall materials that are artificially synthesized, unlike natural products such as gelatin, so the physical properties of the membrane can be improved by selecting various types of chemical raw materials and by chemical modification. can be freely installed,
It has become much easier to obtain industrially suitable wall membrane materials and has brought about a truly revolutionary change in microcapsule manufacturing technology.

In other words, until today, synthetic chemical apolymerization has been applied to wall membrane materials.
Efforts have been made to obtain more advanced microcapsules by performing

Regardless of whether the interfacial polymerization method or the In 5 ltu polymerization method was used, the synthetic polymer wall microcapsule particles were almost spherical mononuclear independent particles that existed separately one by one.

The particle size and film thickness were controlled depending on the purpose. However, the range in which the morphology can be artificially controlled is limited to particle diameter and film thickness, and it has been impossible to impart new properties to the morphology. U.S. Pat. No. 3,041,289 describes a core cell microcapsule agglomerate using gelatin as a wall material, but the purpose of this patent is to be able to control the aggregation of gelatin wall microcapsules. It is seen that there is.

C1 Object of the Invention The present invention mainly relates to the physical form of microcapsules (
The purpose of this research is to obtain microcapsules with new features by changing their morphology, and for all synthetic capsules, including known synthetic polymer wall microcapsules, the main wall material is The present invention provides a method for producing microcapsules made of a synthetic polymeric material and in which a plurality of capsule particles form a plurality of capsules through controlled aggregation.

The present invention is believed to be the first to provide a method for intentionally aggregating synthetic polymer-walled microcapsules.

D0 Structure of the Invention The present invention involves dispersing or emulsifying a hydrophobic substance incompatible with the dispersion medium in a polar dispersant solution of a dispersant or emulsifier so as to form discontinuous microparticles, and then synthesizing it around the microparticles. The pH of a synthetic polymer wall microcapsule mononuclear dispersion containing a hydrophobic substance as a core substance obtained by forming a polymer wall film is lowered in the presence of a male polyelectrolyte and an anionic polyelectrolyte. This is a method for producing a synthetic polymer-walled microcapsule dinuclear dispersion, which comprises aggregating a plurality of mononuclear microcapsules, and then subjecting them to a hardening treatment to prevent them from being dispersed again.

In the production method of the present invention, first, a dispersant or emulsifier having a surfactant effect is dissolved in a polar dispersion medium typified by water, and after dispersing or emulsifying a hydrophobic substance to be a core substance, an interfacial polymerization method is carried out. A synthetic polymer-walled mononuclear microcapsule dispersion is produced using a method such as , in-s mouth polymerization method, or the like. This becomes a -order particle.

Next, add a male polyelectrolyte and an anionic polyelectrolyte such as gelatin, glue, casein, etc. (the initial dispersant or emulsifier may also serve as this, in which case there is no need to add a new one). When acid is then added to lower the pH, a plurality of secondary particles gather together to form secondary particles (agglomerates).

If stirring and addition of acid are carefully performed while sequentially observing and checking with a microscope, secondary particles of the intended size can be obtained with almost uniform size. When lowering -, even if an amphoteric polyelectrolyte such as gelatin is not present, if an anionic polyelectrolyte is present, flocculation will occur, but it is an out-of-control aggregation, and the secondary particles It is not possible to produce a microcapsule binuclear dispersion that is extremely irregular in size and can be used industrially. The use of polyampholytes such as gelatin is one of the keys to the success of the present invention.

After this, if an organic aldehyde compound such as formaldehyde or glutaraldehyde or a hardening agent such as chromium alum is applied, even if the voice rises, it will not become discrete again and return to mononuclear form.

When applying the present invention to carbonless pressure-sensitive recording paper,
- The size of the secondary particles is usually several microns or less, and the size of the secondary particles (agglomerates) is usually several microns to several tens of microns, and can be easily produced in the present invention.

As the anionic polymer electrolyte used in the present invention, those generally used as emulsifiers in the production of microcapsules can be used.5 For example, ethylene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, polyacrylate, etc.
・Rylic acid, styrene-maleic anhydride copolymer ethylene-maleic anhydride-butyl maleate copolymer, polystyrene sulfonic acid, styrene sulfonic acid-methacrylic acid copolymer, isobutylene-mannic anhydride-polymethyl acrylate, acrylic acid -acrylamide copolymer, carboxy-modified PVA, etc., but this does not limit the present invention unless it exceeds the gist of the present invention.

The hydrophobic substance used in the present invention may be a liquid or a gas at room temperature.

For ease of understanding, a specific example of a capsule for carbonless pressure-sensitive recording paper will be shown below, but capsules for other uses can be made in the same way.

E, Examples Example 1゜The hydrophobic substance was 6 parts of 3-diethylamino-6-methyl-7-anilite fluorane (ODB) and 5ASN-296 (
(trade name, oil manufactured by Nippon Petrochemical Co., Ltd.) dissolved in 100 parts.

A styrene-maleic anhydride copolymer having a molecular weight of 100,000 is dissolved in caustic soda to prepare a 5% aqueous solution with a pH of 4.5. 180 parts of the hydrophobic substance (ODB oil solution) was emulsified in 220 parts of this aqueous solution to obtain an emulsion with an average particle size of 2.5 microns.

13 parts of melamine, 25 parts of 37% formalin, and 280 parts of water were adjusted to pH 9 with caustic soda and dissolved by heating at 80°C to obtain a melamine-formalin initial condensate. This initial condensate was added to the emulsion, and the mixture was stirred for 1 hour at a temperature of 60° C., and the formation of mononuclear capsules was confirmed. Next, the liquid temperature is 60
20 parts of a 10% aqueous gelatin solution was added while the mixture was kept at 0.degree. C., and after stirring and mixing, 2% hydrochloric acid was gradually added to adjust the pH to 3, and stirring was continued to obtain binuclear capsules with an average secondary particle size of 9.7 microns. Next, 4 parts of 37% formalin was added and the pH was adjusted to 8 after stirring overnight, but the binuclear capsules no longer dissociated.

Comparative Example 1 When the emulsion of mononuclear capsules obtained in the same manner as in Example 1 was adjusted to pH 3 with 2% hydrochloric acid without adding gelatin, uncontrollable aggregation occurred. This aggregation dissociated when the pH was raised.

Comparative Example 2 When the pH of the emulsion of multinuclear capsules obtained in the same manner as in Example 1 was raised without adding formalin, the emulsion redissociated and returned to mononuclear capsules.

Example 2 The hydrophobic substance was 30 parts of P-phenylphenol-formaldehyde resin (manufactured by Jumin Deretsu) and 5ASN-29.
670 parts was heated and dissolved.

A styrene-maleic anhydride copolymer having a molecular weight of 50,000 is dissolved in caustic soda to prepare a 5% aqueous solution with a pH of 4.2.

360 parts of the above hydrophobic substance was emulsified in 480 parts of this aqueous solution to give an average particle size of 2.3 microns.

30 parts of melamine, 52 parts of 37% formalin, and 520 parts of water were prepared as P)19 with caustic soda, heated at 80°C, and dissolved.
A melamine-formalin initial condensate was obtained. This initial condensate was added to the emulsion, and the mixture was stirred for 1 hour at a temperature of 60° C., and the formation of mononuclear capsules was confirmed. Next, liquid temperature 6
40 parts of a 10% gelatin aqueous solution was added at 0°C, and after stirring and mixing, the liquid temperature was lowered to 40°C, and 4% hydrochloric acid was gradually added to adjust the pH to 3. After stirring for 10 minutes, the liquid temperature was raised to 60°C. When stirring was continued, binuclear capsules with an average particle size of secondary particles of 8.3 microns were obtained.

Example 3 The same procedure as in Example 1 was carried out except that 240 parts of a 6% aqueous solution of imbutylene-maleic anhydride-methyl acrylate copolymer was used as an emulsifier instead of the styrene-maleic anhydride copolymer of Example 1. Thus, mononuclear capsules with an average particle size of 2.5 microns were produced. To this was added 15 parts of a 10% gelatin aqueous solution at 60°C, and after stirring and mixing, 4% hydrochloric acid was gradually added to adjust the pH to 2, and stirring was continued to obtain an average particle size of 6.
8 micron binuclear capsules were obtained.

Example 4 The hydrophobic substances were 3 g of crystal violet lactone and 1 g of benzoylleucomethylene blue, 5ASN-
10g as film-forming material after dissolving in 29697 parts
Sumidur TPL2291 (trimer of hexamethylene diisocyanate, manufactured by Bayer AG) was added and dissolved.

This hydrophobic material was added to 220 g of 5% styrene-maleic anhydride copolymer (pu4.3) with vigorous stirring to form hydrophobic droplets with an average particle size of 3.4 microns. After emulsification, 3.5 g of diethylene triamine and 3 g of caustic soda were dissolved in 300 g of water, added to the system, and the temperature of the system was raised to 60°C.
It was set to ℃.

During this period, PR is maintained around 9.5. At this temperature, 1
When reacted for a period of time, a polyurea resin was formed around the hydrophobic droplets, resulting in microcapsules covering the hydrophobic solution. Add 10% to this mononuclear capsule emulsion at 60°C.
Add 12 parts of gelatin aqueous solution, mix with stirring, add 4% hydrochloric acid to the melon, adjust the pH to 3, and continue stirring to obtain an average particle size of 11.
Dinuclear capsules of Mikuun were obtained.

Example 5 200 parts of the hydrophobic substance used in Example 2 was diluted to pH 3, 5, 5.
% KMA-31 (ethylene-maleic anhydride copolymer manufactured by Monsanto) and emulsified at 60°C so that the average particle size was 2.5 microns. In this emulsion, 20 parts of urea and 2 parts of Resolcif were dissolved. Add 34°0 parts of water, then add 37°
Add 47 parts of % formalin. After stirring at 60°C for 3 hours, 24 parts of a 10% gelatin aqueous solution was added, and after freezing and stirring, 4% hydrochloric acid was clearly added to adjust the pH to 1.5, and stirring was continued, resulting in an average particle size of secondary particles of 10.2. Micron binuclear capsules were obtained.

Synthetic polymer wall membranes manufactured in Examples 1 to 5.

All of the microcapsule dinuclear dispersions were useful for carbonless pressure-sensitive recording paper.

F1 Effects of the Invention According to the present invention, for all synthetic capsules including synthetic polymer wall microcapsules known, the wall material is mainly a synthetic polymer material, and multiple capsule particles are assembled in a controlled manner to form a multinuclear capsule. It has now become possible to produce microcapsules that form .

The synthetic polymer-walled microcapsule assembly produced by the present invention, in other words, the synthetic polymer-walled binuclear capsule, exhibits the following new features not found in conventionally known synthetic polymer-walled mononuclear capsules.

For example, if microcapsules with an oily substance as a core material are coated on paper and then mild to moderate pressure is applied, some of the microcapsules will be destroyed and the core material will be released, but this can then be observed under a microscope. Then, there are only two types of mononuclear capsules: healthy capsules and completely destroyed capsules. For it.

In the binuclear capsule according to the present invention, it seems that only a part of the plurality of primary particles constituting the binuclear capsule is destroyed and the others remain undestructed, depending on the C1 of the healthy capsule and the completely destroyed capsule. An incompletely destroyed binuclear capsule was found. This means that when applied to pressure-sensitive materials such as carbonless pressure-sensitive recording paper, bi-nuclear capsules are more likely to break (i.e. release core material) depending on the applied pressure than mono-nuclear capsules. This is expected to improve the pressure response (that is, the relationship between the applied pressure and the amount of emitted core substance becomes more linear).

[Brief explanation of the drawing]

FIG. 1 is an optical micrograph (4oO
times). FIG. 2 is an optical micrograph (400x magnification) of the microcapsule mononuclear dispersion before the multinucleation treatment in the middle of Example 1. Purification of drawings (no change in content) 1st flash Figure 2 Procedural amendment (method) June 15, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi Stopping torture 1, Indication of the incident 1988 Patent Wish 1 '? OIO No. 3, Relationship with the case of the person making the amendment Patent applicant 4, agent address 5, Mitsubishi Paper Mills Co., Ltd., 3-4-2 Marunouchi, Chiyoda-ku, Tokyo 100, Date of amendment order: April 1982 Month 24th (1L day) (1) Column for a brief explanation of drawings in the specification. "Figure 1 is an optical micrograph (40
0 times). FIG. 2 is an optical micrograph (400x magnification) of the microcapsule mononuclear dispersion before the multinucleation treatment in the middle of Example 1. Figure 1 is a schematic diagram of a synthetic polymer-walled microcapsule dinuclear dispersion produced according to the present invention. Figure 2 is a schematic diagram of a microcapsule mononuclear dispersion before dinucleation treatment according to the present invention. There is.” (2) Amend the drawing as shown in the attached sheet.

Claims (1)

[Claims] 1. A hydrophobic substance incompatible with the dispersion medium is dispersed or emulsified in a polar dispersion medium solution of a dispersant or emulsifier so as to form discontinuous fine particles, and then dispersed or emulsified around the fine particles. Regarding the mononuclear turtle dispersion of synthetic polymer wall microcapsules containing a hydrophobic substance as a core substance obtained by forming a synthetic polymer wall membrane, pH was adjusted in the presence of an amphoteric polymer electrolyte and an anionic polymer electrolyte. A method for producing a synthetic polymer-walled microcapsule dinuclear dispersion, characterized in that a plurality of mononuclei of the microcapsules are aggregated by lowering the microcapsules, and then a hardening treatment is performed to prevent them from being dispersed again.