JPS5855812B2 - Manufacturing method of microcapsules - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing microcapsules collectively in a liquid manufacturing vehicle.

The method involves liquid-liquid phase separation of a relatively concentrated solution of the polymeric material used to form the walls of the microcapsules.

Methods for producing microcapsules in bulk typically require large amounts of liquid production vehicle and generally result in low yields of capsules.

Capsule manufacturing systems and processes that use relatively small amounts of manufacturing vehicle to produce relatively large amounts of microcapsules are believed to be useful from a variety of perspectives.

For example, shipping costs for manufactured capsule products are reduced due to the small amount of vehicle included in the product.

As another example, when the capsule product is applied as a dry film onto a sheet substrate, coating costs are reduced because less liquid vehicle is removed from the substrate.

In the past, physical features with capsule walls! Numerous combinations of materials have been used in the search for compositions to obtain or enable the encapsulation process to be carried out under certain desired or required conditions.

Examples of desirable capsule properties may include small size, impermeability of the capsule wall to diffusion, and capsule 1 strength to withstand the forces exerted during normal handling.

Examples of desirable manufacturing conditions include a relatively high pH of 1, a relatively short turnaround time, and relatively high yields and concentrations.

It is therefore an object of the present invention to provide a method for producing capsules in which the capsules are produced in high yield and in high concentration.

In addition, it is an object of the present invention to provide a method that takes advantage of advantageous manufacturing conditions while requiring relatively short completion times.

Furthermore, it is an object of the present invention to provide a method for producing microcapsules with capsule walls that have a large degree of impermeability.

In addition, it is an object of the present invention to provide a method for producing very small capsules with an outstanding single particle capsule core.

In particular, a capsule manufacturing method is provided in which the capsule wall material is composed of a polymer formed starting from urea-formaldehyde, dimethylol urea, or methylated dimethylol urea, and the wall material is produced by an in situ condensation reaction. It is an object of the present invention to provide.

It is a further object of the present invention to transform the capsule wall material into an improved condensation reaction carried out in the presence of a negatively charged, carboxyl-substituted, linear aliphatic hydrocarbon polyelectrolyte material dissolved in the capsule manufacturing vehicle. It is provided by.

South African Patent No. 6 issued on March 6, 1972
No. 2/939 and corresponding U.S. Pat. No. 351 in many respects.
No. 6941 discloses a method for producing microcapsules by in situ polymerization of amides or amines with aldehydes.

There is no disclosure herein of the use of negatively charged polyelectrolyte materials to modify or otherwise affect polymerization reactions or products.

US Pat. No. 3,516,941 contains a disclosure of the adverse effects found in this type of capsule manufacturing process when using certain wetting agents.

U.S. Patent No. 3755, issued August 28, 1973
No. 190 discloses a method for making microcapsules in which the capsule wall material is a polyhydric phenol/aldehyde polymeric material produced in the presence of polyvinyl alcohol.

U.S. Patent No. 3726 issued April 10, 1973
No. 803 discloses a composite capsule wall structure of a hydrophilic polymeric material modified by a hydrophobic polymeric material.

Hydrophobic polymeric materials are disclosed as in situ formed condensates of polyhydric phenolic materials and aldehydes.

U.S. Patent No. 30163 issued January 9, 1962
No. 08 discloses a process for making capsules by continuous polymerization of urea/formaldehyde resin dissolved in an aqueous production vehicle with a polymeric wetting agent.

This method uses a urea/formaldehyde resin as the starting material and a small amount of wetting agent to maintain the emulsion during continuous polymerization.

According to the invention, urea and formaldehyde, dimethylol urea (DMU) or methylated dimethylol urea (MD
Using MU) as a starting material, the condensation polymer produced in an aqueous capsule-making vehicle results in a brittle film of capsule wall material and nothing more can be obtained.

In order to obtain a suitable molecular weight for phase separation, the polymeric material produced from the aqueous solution of the starting material has a tendency to separate from the solution as crystals, lumps, or solids.

This precipitation phase separation can be adjusted to produce a relatively concentrated liquid separated phase of polymeric material, but this adjustment requires frequent and precise dilution to maintain a normal polymer concentration. I need.

For example, capsule manufacturing methods using urea/formaldehyde production and stepwise and continuous dilution of the manufacturing vehicle can yield capsules of sufficient quality for various uses, although the capsule wall material is brittle and weak. can.

Dilution of the manufacturing vehicle in previously developed capsule manufacturing processes that utilize the formation of urea/formaldehyde polymers is required to reduce the formation of solid lumps of polymeric material; Dilution is also necessary to maintain the capsule production system at a workable viscosity.

Urea/formaldehyde polymeric materials have certain desirable qualities for use as microcapsule wall materials.

However, previously disclosed methods require substantial improvements in the production of microcapsules in order to produce polymeric materials in commercially acceptable quantities and quality.

The process of the present invention has the advantage of well-produced condensation polymers, but without the disadvantages of required dilution and lump formation that plagued previous processes, urea and formaldehyde, dimethylol urea, or methyl The present invention provides for the production of capsule walls by polymerization of dimethylol urea.

With respect to dilution and agglomeration, it is noteworthy that the capsule manufacturing method of the present invention operates efficiently at higher capsule concentrations than previously thought possible.

Furthermore, at such high capsule concentrations, the ferrous viscosity remains within effective, operable liquid limits in the manufacturing process of the present invention.

In addition, the manufacturing method of the present invention provides a method for manufacturing capsule walls that have significantly greater impermeability and strength compared to urea/formaldehyde polymer capsule walls made by previously known methods.

The iron-based component materials specifically used in the process of the present invention are those considered necessary to realize all of the benefits described herein, and contain an average of approximately It is a negatively charged, polymeric polyelectrolyte material with a linear aliphatic hydrocarbon backbone depicting two carboxyl (or anhydride) groups.

The use of appropriate types and amounts of system modifiers allows the production of microcapsules with high capsule concentrations of DMU or MDMU wall material, low vehicle viscosity, and urea/formaldehyde at advantageous high pH conditions. is necessary.

Previously, polyvinyl alcohol has been used as a support polymer in the production of certain special condensation polymers in microcapsule manufacturing.

The condensation polymers in this type of production process are products of polyhydric phenolic substances having at least two phenolic hydroxyl groups and aldehydes.

However, polyvinyl alcohol is disclosed as the only preferred support polymer and only phenolic materials having at least two phenolic hydroxyl groups are disclosed to be used as co-reactants of the aldehyde.

The present invention uses urea/formaldehyde, dimethylol urea, or methylated dimethylol urea as a starting material to form a condensation polymer as a capsule wall, and provides a process that does not have the disadvantages and has the advantages previously disclosed. This is what we provide.

The dimethylol urea or methylated dimethylol urea starting material can be used either as a monomer or as a low molecular weight polymer thereof, and references to this in this application are meant to include all these forms.

The system of the present invention is similar in certain respects to the polyvinyl alcohol supported polymers described above.

However, the system modifiers of the present invention must have a negative carboxyl charge in aqueous solution, and only certain carboxyl-substituted materials have been found to be particularly useful.

The inventors +3 do not believe that the system modifier forms a strong complex or substantial bond with the starting material before polymerization, but believe that this would interfere with the polymerization reaction in some way. There is.

Although the mechanism of this interference is unknown, the effect of this interference allows microcapsules to be produced en masse by in situ polymerization at surprisingly high viscosity and high concentration in the production vehicle.

The system modifier is hardly contained in the finished capsule wall.

The system modifier increases the optimum pH for polymerization, increases the polymerization component Q efficiency, and lowers the viscosity of the system even at high polymer concentrations. It has an active effect.

Nevertheless, the finished capsule wall contains only a small amount of system modifier.

To be effective, the system modifier must be introduced into the capsule manufacturing system before the polycondensation reaction begins.

Although the inherent brittleness of the resulting polymeric capsule wall material is improved somewhat by a negligible residue of the modifier, the effect is mostly a fortuitous advantage.

Examples of preferred carboxyl group-based modifiers include ethylene-anhydrous maleate copolymer (EMA), methyl vinyl ether-
Maleic anhydride copolymer (PVMMA), propylene-
Maleic anhydride copolymer (PMA), inbutylene-maleic anhydride copolymer (iBMA), butadiene-maleic anhydride copolymer (BMA), vinyl acetate-maleic anhydride copolymer (PVAMA), etc. and polyacrylic acid or similar polyacrylates.

Furthermore, it is clear that there is a molecular weight range for preferred system modifiers that provides the best results.

Preferred system modifiers enable and maintain the polymerization of the capsule-making system with urea and formaldehyde, DMU or MDMU at fairly low and workable viscosities.

Negatively charged substances that are normally suitable as system modifiers are not suitable at very low molecular weights.

Inexplicably, system modifiers below a certain molecular weight will thicken and gel the system, whereas modifiers with appropriately sized high molecular weights will maintain the viscosity of the system at a reasonably low level.

This viscosity effect is not yet understood and no further explanation can be given; however, a high molecular weight modifier is used to reduce the viscosity, and a low molecular weight modifier is used to increase the viscosity.

Rather than exhibiting a sharp change from usable to unusable, the critical molecular weight is indicated by a transition from favorable viscosity to gelation as the molecular weight decreases.

Moreover, the critical value of low molecular weight varies slightly depending on the type of suitable system modifying substance.

For example, preferred ethylene-maleic anhydride copolymers should have a molecular weight of about 1,000 or more, methyl vinyl ether-maleic anhydride copolymers should have a molecular weight of about 250,000, and polyacrylic acids should have a molecular weight of about 20,000 or more. .

The material contained within the capsule walls formed according to the present invention, i.e., the capsule inner phase or capsule core material, is relatively unimportant to the practice of the present invention and may be any material that is substantially water-insoluble; Any substance may be used as long as it does not interfere with the intended capsule wall material or other components of the capsule manufacturing system and does not impair the process.

Some examples of materials that can be used as the internal capsule phase include, among many others, water-insoluble or substantially water-insoluble liquids such as olive oil, fish oil, vegetable oil, whale oil, mineral oil, xylene, toluene, kerosene, Biphenyl chloride and methyl salicylate: Similar substantially water-insoluble solid substances that exhibit meltability, such as naphthalene and cocoa butter: Water-insoluble metal oxides and salts: Fibrous materials, such as cellulose or asbestos: Water-insoluble synthetics Polymeric substances: Minerals: Pigments Nigaras: Elemental substances including solids, liquids, and gases:
There are seasonings: fragrances: reactants: bactericidal compositions: physiological compositions, fertilizer compositions, etc.

The method of the invention particularly and preferably, in one embodiment,
Preparing an aqueous single phase solution of the system modifier and urea and dispersing the intended capsule core material within this solution (
This core material is substantially insoluble in the supernatant solution and does not react with either the system modifier or the urea).

When formaldehyde is added to the system while maintaining its dispersion power, the reaction between urea and formaldehyde causes the urea/formaldehyde polymer material to form its own characteristic liquid solution phase of relatively high concentration of urea/formaldehyde. Separate from the solution.

A separate liquid phase containing urea/bormaldehyde wettingly envelops the particles of the dispersed capsule core material, creating liquid-walled immature capsules.

Continuous reaction of the urea/formaldehyde materials, preferably with stirring, results in a solid, substantially water-insoluble capsule wall.

Stirring is not necessarily required to carry out the condensation reaction.

What is important is that (a) there is no dilution step in the process after the iron system has been blended and the capsule wall forming condensation reaction has started, and (b) the presence of a system modifier allows for high concentration urea/urea with relatively low viscosity. Formaldehyde polymers can be produced and (e) the resulting high-concentration-low-viscosity system allows separation of the liquid phase, followed by polymerization and solidification to produce capsules, in a production vehicle that was not previously possible. It is carried out all at once at a concentration (volume) of .

In another embodiment of the invention, an aqueous single phase solution of dimethylol urea or methylated dimethylol urea and the system modifier or supporting colloid is prepared and the internal phase capsule core material is dispersed therein.

This internal phase capsule core material consists of an oily solution of a colorless color-forming dye material used in carbonless copy paper, and for convenience of explanation is hereinafter referred to as the "standard internal phase" or "standard IpJ."

Preferably by stirring and heating, the condensation reaction proceeds and the condensation polymer separates from the solution as a liquid solution phase;
The particles of dispersed capsule core material are wetted and surrounded to produce a liquid-walled immature capsule that eventually solidifies into a substantially water-insoluble capsule wall.

Alternatively, the various system components can be combined in any order, with the only limitation being that the system modifier must be present in the system when the polymerization reaction begins.

The capsule core material can be dispersed in the iron system at any time before the separate liquid phase of the polymeric material becomes solid or polymerized to such an extent that the dispersed capsule core particles are encapsulated by the resulting polymer.

Even when modified with a system modifier, the polymerization reaction is a condensation reaction that occurs in an acidic medium.

This condensation can be carried out in an aqueous system with a pH of about 0 to 7, although the required time and temperature can be varied to optimize the reaction.

In correlation with the effect of the system modifier Q on the condensation reaction, the preferred pH for the operation of the present invention is 2.5 to 5.0, and the most preferred pH is 3.5.

Regarding the relationship between the amounts of urea and formaldehyde used, it has been found that the molar ratio of formaldehyde to urea is at least 1.6, preferably from 1.6 to about 3.

After the reaction has proceeded to the point where the capsule walls have solidified and capsule production is complete, the capsules are separated from the production vehicle by filtration and washed with water.

The capsule is then placed in a forced air dryer to dry the capsule walls.

However, it should be understood that the capsule need not be dry walled or separated from the liquid vehicle prior to its use.

If necessary or desired for a particular purpose, the capsule products of the present invention can be added to a liquid carrier (manufacturing vehicle) for applications already taught in the prior art, such as paper-coating compositions, paints, pesticides, etc. Individual capsules prepared by the method of the present invention, provided as a capsule slurry in (or otherwise), can be bispherical and have diameters from less than 1 micron to about 100 microns. However, the preferred size range is about 1 to 50 microns in diameter.

The capsule products of the present invention are comprised of individual capsules with each entity having one particle of capsule core material as the internal phase or individual capsules with aggregates having several particles of capsule core material. Made in any form of aggregate.

Capsule aggregates are formed with diameters ranging from several microns to several hundred microns, depending on the state and size of the core material they contain.

Unless otherwise specified below, all percentages and parts are by weight and all temperatures are in °C.

All solutions +-3 are aqueous unless otherwise specified.

Example 1 In this preferred embodiment, a negatively charged ethylene-maleic anhydride copolymer is used to modify a urea/formaldehyde capsule manufacturing system to produce capsules ranging in size from 1 to 15 microns.

The capsule contents (standard internal phase) consist of an oily solution of a carbonless, color-forming dye material for use in copy paper, which is described below in connection with the testing of the capsule product according to this example.

Hedimethylol urea (D) in a beaker equipped with a magnetic stirrer
DMU is dissolved in 200 cc of water by adding MU) 20f to 200 cc of boiling water.

The solution was cooled to about 45°C and then added with about 2.7 cc of 20 percent sodium hydroxide, hydrolyzed ethylene-
Maleic anhydride copolymer (molecular weight 75,000-9,000
0) LOOP and resorcinol 11 are added to this.

The pH of the final solution is approximately 3.5.

Standard internal phase 1801 is added into the solution as capsule core material and emulsified.

The iron system is then heated to a temperature of 55°C in a water bath.

After continuing stirring and heating for 2 hours, the temperature was lowered to room temperature (approximately 25°C).

The produced capsules of the oily dye solution have a uniform size ranging from 1 to 15 microns, representing over 40 volume percent of the capsule manufacturing system.

Example 2 50 g of a 10 percent solution of methyl vinyl ether-anhydrofrey 4 copolymer (molecular weight 75,000) (Gantrez 149), resorcinol 0.51.20 percent NaOH 1.4 cc and 101' boiling water (95°C)
) to prepare a solution by mixing 10 g of dimethylol urea dissolved in

The pH is adjusted to 3.5.

The standard internal phase (standard IP) 90? described in Example 1? (10
0 cc) is added into the solution and emulsified, and the emulsion is placed in a water bath maintained at a temperature of 55°C.

After 4 hours, drawdown of this emulsion on a CF test sheet yielded a reflectance value of 63%.

The CF drawdown test is a method of testing capsule wall formation.

The capsule emulsion containing all of the capsule-forming ingredients is coated onto reactive CF paper.

Color development is achieved by reaction of the dye with the CF coating.

Formation of the capsule wall is evidenced by a reduction in color when the emulsion is applied to the back column and the reflectance of the applied area is measured by an opacity meter.

Example 3 As described in Example 2, 2 of polyacrylic acid (AcrysOlA-5, molecular weight 35,000 or less)
5% solution 20? , water 30P, resorcinol 0.5P
, about 1.5 cc1 of 20% NaOH and boiling water (95°C)
Mix 1(l) of dimethylol urea dissolved in 10 M'.

Adjust pH to 3.5. Standard IP9 o? (1ooc
c) is added to the solution and emulsified.

The solution is placed in a water bath maintained at a temperature of 55°C.

After 1 hour and 20 minutes, a sample of the emulsion coated on a CF test piece exhibited a reflectance value of 61%.

Example 4 Propylene-maleic anhydride copolymer (specific viscosity Q, 55
5 of 10% solution of ), 0.5 of resinol of resin, 2
1.4cc of 0% NaOH and 100P hot water (95℃
) to form a solution.

The pH is adjusted to 3.5.

Standard xp9oy (io 0cc) is added to the solution to emulsify and the solution is placed in a water bath maintained at a temperature of 55°C.

After 1 hour, a sample of this emulsion applied onto a CF test piece had a reflectance value of 68%.

Example 5 Inbutylene-maleic anhydride copolymer (specific viscosity 1.9
A 10% solution of 9) is made by dissolving with the use of NaOH.

The resulting solution is then treated with a strong cation exchange resin (Ambarai IR120).

The pH of this solution is 3.5 when diluted with 2 parts of water.

10 of the above-mentioned inbutylene-maleic anhydride copolymer
% solution 5O? , resorcinol o, 5P and 10 t of dimethylol urea dissolved in 100 ml of hot water at 95° C. are mixed.

Standard 1p91' (100 CC) is added into the solution and emulsified and placed in a water bath maintained at a temperature of 55°C.

After 1 hour, a sample of this emulsion coated on a CF test piece showed a reflectance value of 52%.

A sample of this emulsion when coated on non-reactive paper showed a reflectance of 53%.

Example 6 13% solution of butadiene-maleinoic anhydride copolymer (Borgwarner, Maldene 285) 38
．． 5? , resorcinol 0.51.20% Na0HQ,
9 cc, 10? dissolved in 11.5 f of water and 100 g of 95°C hot water. Prepare a solution with dimethylol urea.

Adjust pH to 3.5. Standard 1p91' (100cc
) is added to this solution to emulsify it and then placed in a water bath maintained at a temperature of 55°C.

After 1 hour and 15 minutes, a sample of this emulsion applied onto a CF test piece showed a reflectance value of 62%.

Example 7 40 oz water, ethylene-anhydrous Frey 4 copolymer (EM
10% of A 31 , molecular weight 75,000-90,000)
A solution consisting of 200 P of aqueous solution and 2 g of resorcinol is adjusted to pH 3.5 using 20% NaOH.

400 mg of standard IP as described in Example 1 in this solution.
Add rd and emulsify.

Sample A The above emulsion 484? 22% of methylated dimethylol urea resin (American Sianami Fa, Beetle 5° Resin) while stirring in a water bath at 55°C.
．． Add a solution of 8P and 15.0y' of water.

Sample B 4841 parts of the above emulsion was mixed with methylated dimethylol urea resin (American cyanamide male, 13eetle 6!5 resin) while stirring in a water bath at 55°C.
Add a solution of 20.1 F and 17.7 F of water.

Samples A and B, and the bunch prepared in Example 1 above (
Sample C) was ground and stirred in a water tank, respectively.Heating to the water tank was stopped 2 hours after the addition of the reactant.

Three batches of samples were drawn down onto CF sheets at various time intervals to test the extent of encapsulation by application.

The reflectance values below were obtained when each batch was tested after stirring overnight (19 hours).

CF Top Top Lower Down Opacity Meter Reading Each batch of these samples A, B, C was quantified and coated to produce a satisfactory CB sheet.

Example 8 Water 10oS', methyl vinyl ether-maleic anhydride copolymer (Gantrez 169, molecular weight 1125
000) (7) 10% solution 5 (l and fillet resorcinol/1
/ 0.5 F mixed solution with 20% NaOH to pH 3,
Adjust to 5.

Standard IP100rrLl is added to this solution and emulsified.

The emulsion was placed in a water bath at 55°C and methylated dimethylol urea resin (Beetle 65) 10? And add 8 to 9 liters of water to this.

Stirring continued for 19 hours, but heating was stopped after 3 hours.

The drawdown reflectance reading of the CF sheet after 19 hours was 60.

Example 9 130 g of water, polyacrylic acid (Acrysol A5
, molecular weight 35,000 or less) 40% solution 2 (1) and a solution of resorcinol 0.51 with 20% NaOH to pH 3,
Adjust to 5.

Add 100 ml of standard IP into it and emulsify.

The emulsion was placed in a water bath at 55°C and methylated dimethylol urea resin (Beetle 65) 10? A solution of 8.91 parts of water and 8.9 parts of water is added to this.

Stirring continues for 19 hours, but heating is discontinued after 2.5 hours.

After 19 hours, the drawdown reflectance value reading on the CF sheet was 74.

Example IO Propylene-maleic anhydride copolymer (specific viscosity 0.55
) 10% solution 501, water 100g, methylated dimethylol urea resin (Beetle 65.100% solids) 1
01 and resorcinol O,5? A mixed solution of 20% N
Adjust the pH to 3.5 with aOH.

Add standard IP90P (100ml>) to this solution, emulsify it, and place it in a water bath at 55°C.

After 2 hours, a sample of the emulsion coated on a CF test piece had a reflectance of 60%.

The sample coated on non-reactive paper had a reflectance of 61%.

Example 11 Inbutylene-anhydrous Frey 4 copolymer (specific viscosity 1.99
) 10% solution 5 (1, water 100f 1.% tylated dimethylol urea resin (Beetle 65) 10g and resorcinol 0.51 mixed solution with NaOH pH 3,
Adjust to 5.

Standard IP90P (100 ml) is added to this solution, emulsified, and placed in a water bath at 55°C.

After 2 hours, a sample of the emulsion applied to a CF test piece had a reflectance of 53%.

When applied to non-reactive paper, the reflectance was 54%.

Example 12 13% solution of butadiene-maleic anhydride copolymer (Maldene 285) 38. Fl
, water 101.5 P, methylated dimethylol urea resin (
Beetle 65) 107 and resorcinol 0
．． The pH of the mixed solution of 51 is adjusted to 3.5 with NaOH.

Standard Ip90y (100 mO) is added into this solution to emulsify and placed in a water bath at 55°C.

After 2 hours and 30 minutes, the sample applied to the CF test piece had a reflectance of 48%.

Samples coated on non-reactive paper had a reflectance of 50%.

The amounts and types of capsule-making materials used in each of the above examples may be any of those previously described.

The pH during capsule manufacturing may be pH 0-7 and the molar ratio of formaldehyde to urea may be between 1.6 and 3.

Increasing the pH of the system helps increase the temperature of the capsule manufacturing system.

Usable operating temperatures are 25 to 100'C at room temperature, but preferably about 50 to 55'C.

When a stirring device is used, by adjusting the degree of stirring, the size of droplets to be used as the capsule core material can be adjusted to any size between several microns to several hundred microns.

Furthermore, by varying the amount of core material intended, the amount of finished capsule, ie, the amount of internal phase relative to capsule wall material, can be varied.

Capsules typically contain less than 50% to 95% internal phase.
Even more than that can be made.

In practicing the present invention, the amount of system modifier in the capsule manufacturing system is believed to be important, but a minimum amount ensures adequate interference with the condensation reaction to form the polymer. The maximum amount is determined by economic reasons.

Of course, if the concentration of system modifier becomes too high, the viscosity of the iron system becomes unmanageably high.

Typically, the capsule manufacturing system should contain at least 0.75 percent system modifier.

Regarding the maximum value, it must be remembered that it is not possible to determine an exact general maximum value due to the differences in solution viscosities of these various amounts of material resulting from the variety of materials available.

It can be said that there is almost no use or need for more than 10%.

However, amounts of system modifier up to about 15 percent can be used if desired.

Generally speaking, it can be said that the amount of system modifier used will modify the polymerization of urea and formaldehyde in one embodiment of the invention and the polymerization of dimethylol urea or methylated dimethylol urea in another embodiment. in an amount sufficient to enable modification of the polymer to form a polymeric capsule wall;
That's what it means.

It goes without saying that the invention described above can be modified in various ways.

These changes are not considered to be a departure from the spirit and scope of the invention, and many of these changes are within the scope of the following claims.

Claims (1)

[Scope of Claims] 1. A method for producing microcapsules in batches in an aqueous production vehicle, comprising: (a) monomeric dimethylol urea, methylated dimethylol urea, and low molecular weight polymers thereof; an ethylene-maleic anhydride copolymer, an ethylene-maleic anhydride copolymer, Methyl vinyl ether-maleic anhydride copolymer, polyacrylic acid, glopyrene-maleic anhydride copolymer, inbutylene-maleic anhydride copolymer, butadiene-maleic anhydride copolymer, and vinyl acetate-maleic anhydride copolymer a system-modifying material selected from the group consisting of: and particles of the intended capsule core material substantially insoluble within said system, wherein said modifying material is present before the initiation of polycondensation and before addition of said particles. ←) The dimethylol urea or methylated dimethylol urea is polycondensed under acidic conditions to form a polycondensate, so that soluble Separating the polycondensate exceeding the molecular weight into a liquid-liquid phase and continuously polycondensing the separated polycondensate to form individual solid capsule wall materials around the dispersed capsule core material particles; A method for producing microcapsules, characterized by: 2. The method according to claim 1, wherein the polymerization condensation reaction is carried out while the aqueous system is continuously stirred. 3. The ethylene-maleic anhydride 4 copolymer has a molecular weight of 1000 or more, and the vinyl methyl ether-maleic anhydride copolymer has a molecular weight of about 25oOo. or more, and the polyacrylic acid has a molecular weight of about 2000
The method according to claim 1, characterized in that the method has a molecular weight of 0 or more. 4. The method of claim 1, wherein the aqueous production vehicle has a volumetric capacity of 60% or less relative to iron. 5. Claim 1, characterized in that the aqueous production vehicle is less than 50% by volume relative to the iron-based production vehicle.
Section method. 6. The method of claim 1, wherein the aqueous system comprises an additional compound selected from the group consisting of resorcinol, orcinol and gallic acid. 7. The method of claim 6, wherein the additional compound is present in the system in a weight ratio of 5 to 30 percent relative to the bound urea in dimethylol urea or methylated dimethylol urea. Method. 8. The method of claim 1, wherein the pH value of the aqueous production vehicle is maintained between 3 and 7 throughout the step. 9. The method of claim 1, wherein the amount of iron-based modifying material is about 0.75 to 15 percent by weight of said aqueous production vehicle (7). 10. The method of claim 1, wherein the dimethylol urea or methylated dimethylol urea is added to an agitated aqueous system containing the modified material and the capsule core material. 11 Stirring unit containing the starting material and the modified substance
2. The method of claim 1, wherein the particles are dispersed in the phase aqueous solution system after it has been prepared. 12. The method of claim 11, wherein the amount of said System Q modifier is from about 0.75 to about 15 percent by weight of said aqueous production vehicle.