JPH0259040A - Microcapsule - Google Patents

Abstract

PURPOSE:To prepare a microcapsuled org. acid having hydrophilicity as a core by dissolving or dispersing an org. acid or phosphoric ester in a hydrophobic substance liquid at ambient temp. to use the same as a core substance. CONSTITUTION:A 6C or more org. acid having hydrophilicity such as caproic acid or enanthic acid or phosphoric ester such as tributyl phosphate is dissolved or dispersed in hydrocarbon, natural fat and oil (triglyceride) or phthalic ester liquid at ambient temp. Subsequently, a wall film of gelatin is formed by a complex coacervation method. By this method, the org. acid or phosphoric ester having hydrophilicity difficult to encapsulate is used as a core substance to prepare a microcapsule.

Description

Detailed Description of the Invention (-) l-1 Field of Invention (Industrial Application Field) The present invention relates to organic acids having 6 or more carbon atoms (hereinafter simply referred to as "organic acids") or phosphoric acid. The present invention relates to microcapsules having esters as core materials, and more specifically to microcapsules formed by coating these core materials with a gelatin wall film using a complex coacervation method or a simple coacervation method.

The microphone of the present invention can be used by being added to various surface chemical materials such as surfactants, magnetic fluids, adhesives, paints, lubricants, and materials.

[Conventional technology]

There are many known methods for microencapsulating hydrophobic substances, such as the 21-merlenox coacervation method, the simple coacervation method, the interfacial polymerization method, the in-5iLu polymerization method, and the submerged drying method. The most typical method is the complex coacervation method described in US Pat. No. 2,800,457.

This method consists of (1) ionizing a hydrophilic colloid sol in water, and mixing a hydrophilic sol and a core substance having an opposite charge to the sol to create an oil-in-water (0/W) solution.
The process of forming an emulsion. (2) A step of causing coacervation by adding water to the emulsion or by adjusting pII31:i to cause coacervate droplets to adhere around the core material. (3) A step of cooling a drop onto the core cell to a temperature below the gel point of the initial woody colloid to gel it. (4) Adding a hardening agent to crosslink the wall film. (5) The process consists of adding an aqueous alkali hydroxide solution to neutralize and raise the temperature to prevent the capsules from coming together.

That is, the combination coacerhesion method uses two types of colloidal substances with opposite charges, for example, positively charged colloidal substances such as gelatin, casein, albumin, and fibrinogen, and Arahiago J8, carbo-1-dimethylcellulose, -1. is formed into a complex core cell that becomes the capsule wall membrane using electrical interaction with negatively charged colloid particles such as cellulose phthalate.
It's something like U.

[Problem to be solved by the invention 1 to 4''] The formation of such a complex core cell is caused by proteins aggregating into a sol in an unstable state near their isoelectric point. You can see it.

The important points in microencapsulation are to form the sol efficiently and to efficiently adhere the sol to the surface of the core substance and gel it.

Since the sol itself is an extremely surface-active substance, the larger the free energy on the surface of the core substance, the more easily it will adhere to the core substance and become stable. Conversely, if the free energy on the surface of the core material is small, then the core material may be an organic acid or phosphate ester (
When the hydrophobicity is not sufficiently large as in y and the sol has a certain degree of hydrophilicity, it becomes difficult for the sol to adhere to the surface of the core material, making it difficult to carry out the microencapsulation reaction with good yield.

Furthermore, in the conventional method, in the step (5) of adding and neutralizing an aqueous alkali hydroxide solution, a part of the organic acid or phosphoric acid ester of the core substance is also neutralized and converted into an organic acid metal salt or a phosphate metal salt. It also had the disadvantage of being

(B) Structure of the Invention [Means for Solving the Problems] The present inventors, in order to solve these problems, have diligently investigated J.L.
As a result of repeated research, we discovered that this problem could be solved by dissolving or dispersing an organic acid or phosphoric ester (negative) in a hydrophobic substance that is liquid at room temperature, and using this solution or dispersion as a core material. The invention was completed.

The organic acid serving as the core material in the present invention has 6 or more carbon atoms, and preferably has hydrophilicity,
For example, caproic acid, enane 1-rM, caprylic acid, pelargonic acid, capric acid, undecylic acid, oleic acid,
These include se1-leic acid, erucic acid, linault acid, F1, lylunic acid, and arachidonic acid.

Non-acid esters include phosphate esters and phosphite esters. These monoesters and diesters are acidic, and triesters are neutral, but triesters are easily hydrolyzed by acids or alkalis, resulting in -.
becomes a diester. For this reason, triesters also have some degree of hydrophilicity.

Specific examples of phosphate esters include hydrophilic ones such as tributyl phosphate, triphenyl phosphate, tricresyl phosphate, hensyl diphenyl phosphate, allyl diphenyl phosphate, ethyl diphenyl phosphate, and octyl phosphate.
ruphenyl, 2-ethyl nonate-1-sildiphenyl,
Examples include acidic diphenyl phosphate, acidic dicresyl phosphate, triphenyl phosphite, and acidic diphenyl phosphite. In addition, the phosphoric acid esters (i) of the present invention may also include metaphosphoric acid esters 1n.

Examples of liquids that dissolve or disperse organic acids or Nistelha phosphates (at room temperature) include (liquid hydrocarbons, natural oils and fats (triglycerides), phthalate esters, adipate esters, or citric acid esters, which are hydrophobic). (hereinafter referred to as "hydrophobic liquid").

Specifically, hydrocarbons include mineral oil, octane, decane, petroleum naphtha, solvent naphtha, liquid paraffin, etc.;
Natural oils and fats (triglycerides include animal oils such as beef tallow, lard, whale oil, shark oil, and mutton fat; vegetable oils such as rapeseed oil, sesame oil, soybean oil, cottonseed oil, and safflower oil; phthalate esters include dibutyl phthalate) , dioctyl phthalate, etc.; examples of adipate esters include dioctyl adipate, etc.; examples of citric acid esters include tributyl citrate, etc.

The microcapsules of the present invention are prepared by dissolving or dispersing the organic acid or phosphate ester x1 in the hydrophobic liquid, and then forming a gelatin wall film by a conventional complex coacervation method or simple coacervation method. This is what I got.

The blending ratio of the organic acid or phosphoric acid ester and the hydrophobic liquid is preferably 0.1 to 60% by weight, with the total amount of both being 1. 0
．． If it is less than 1% by weight, the effect of the organic acid or phosphoric acid ester will not be fully expressed, while if it exceeds 60% by weight, it will be difficult to encapsulate, and if it is neutralized with alkali hydroxide after capsule formation, the core material will be The organic acids or phosphoric esters contained therein are likely to be affected, so each is not preferred.

The microcapsules of the present invention include surfactants, magnetic fluids,
It is used by being added to various surface chemical materials such as adhesives, paints, lubricants, and film materials, and exhibits oxidation-preventing, friction-preventing, and rust-preventing effects.

[Effect]

A solution or dispersion obtained by dissolving or dispersing an organic acid or phosphoric acid ester in a hydrophobic liquid can be used to form a gelatin wall film by the usual complex coacervation method or simple coacervation method. Furthermore, even when neutralized with alkali hydroxide in the capsule production process, the organic acids and phosphoric acid esters in the core material are hardly affected.

This is because in the solution or dispersion, there is mainly a hydrophobic liquid near the interface between the core material and water, and this increases the free energy of the core material'ff/water interface, causing the sol to reach the surface of the core material. This is thought to be because it becomes easier to adhere and encapsulation is performed with good yield. Furthermore, since no organic acid or phosphoric acid ester is present near the interface, neutralization with alkali hydroxide has little effect.

(Example〕 Hereinafter, the present invention will be explained in more detail in Examples.

In addition, in the examples, "%" indicates "% by weight".

Example 1 10% gelatin water? Warm 300g of Yoonya to 43°C, and add a 10% cottonseed oil solution of caprylic acid at 43°C9.
0 g was added and emulsified using a homomixer to form fine oil droplets with an average particle size of 3.5 μm.

Then, while stirring at a rotation speed of 400 rpm,
300 g of a lO% gum arabic aqueous solution warmed to 100 g was added.

Next, 1400 g of pure water heated to 40°C was gradually added, and the pH was further adjusted to 4 using a 10% acetic acid aqueous solution.

Subsequently, the liquid temperature was continuously lowered to 10°C.

The cooling temperature gradient was -1°C/3 minutes.

When the liquid temperature dropped to 10°C, 30 mff1 of a 50% aqueous solution of glutaraldehyde was added.

Next, IN NaOH was added to adjust the pH to 7, and the temperature was raised to return to room temperature.

As a result, a dispersion of polynuclear capsules with an average particle size of 30 μm was obtained.

This capsule had sufficient wall strength and could withstand filtration.

Example 2 Oleic acid was used instead of caprylic acid in Example 1, lard was used instead of cottonseed oil, and a homomixer was not used for dispersion, only stirring at a rotational speed of 40 rpm was used, but the other conditions were the same as in Example 1. When the capsules were manufactured, a mononuclear capsule dispersion having an average particle size of 50 μm was obtained.

This capsule had wall strength that could withstand filtration.

Example 3 Pelargonic acid instead of oleic acid in Example 2,
Capsules were manufactured under the same conditions as in Example 2 except that liquid paraffin was used instead of lard, and the average particle size was 40.
A mononuclear capsule dispersion of μrn was obtained.

This capsule had wall strength that could withstand over-separation.

Examples 4 to 6 Capsules were manufactured under the same conditions as in Example 1 except that the concentration of caprylic acid in the cottonseed oil solution of caprylic acid in Example 1 was 20.30.40%. A similar capsule dispersion was obtained.

This capsule had wall strength that could withstand filtration.

Example 7 Example 2 except that tricresyl phosphate was used instead of oleic acid and mineral oil was used instead of lard.
As a result of manufacturing capsule bodies under the same conditions, the average particle size was 50
A mononuclear capsule dispersion of μm size was obtained.

This capsule had wall strength that could withstand filtration.

Comparative Example 1 90 g of 10% cottonseed oil solution of caprylic acid in Example 1
When 90 g of caprylic acid was used instead, no capsules were formed.

Comparative Example 2 90 g of 10% lard solution of oleic acid in Example 2
When 90 g of oleic acid was used instead, no capsules were formed.

Comparative Example 3 10% Ra 1' solution of oleic acid in Example 2 90
When a 70% lard solution of oleic acid was used instead of oleic acid, capsules were formed, but the film strength was very low and a large percentage of the capsules were destroyed in the filtration step A1.

The filtration valve 111 obtained in Examples 1 to 6 [later capsules and a small amount of capsules that could be filtered and separated in Comparative Example 3] was analyzed for the ratio of organic acid/sodium organic acid in the core material by the following method. .

The capsules are filtered and washed with pure water, and then filtered and separated again.

Analysis of the organic acid I-lium was carried out by determining sodium by atomic absorption.

Analysis of organic acids was performed by grinding the capsules in a mortar, adding a 1/1 solution of tetrahydrofuran/ethanol, and then adding 10% NaOH dissolved in a 9:1 ethanol:water (YL mixture) medium. The acid value was determined by neutralization titration at night.

The ratio of organic acid to sodium organic acid (-100 x organic acid/(organic acid to organic acid 1-IJum) (%)) of the core material 11 of the nuclear capsule obtained from the analysis value is as follows. there were.

Example 1 98% Example 2 97% Example 3 98% Example 4 95% Example 5 91% Example 6 69% Comparative Example 3 11% As shown above, the microphone 11 capsule of the present invention has a core Most of the substances remain as organic acids.

Comparative Example 4 90 g of tricresyl phosphate was used instead of 90 g of 10% 1 L oil solution of tricresyl phosphate in Example 7, and the other conditions were the same as in Example 7. No capsules were formed. There wasn't.

(c) Effects of the Invention The microcapsules of the present invention are novel in that their core material is a hydrophilic organic acid or phosphate ester, which has been difficult to encapsulate in the past, and their wall film is gelatin.

In addition, even when neutralized with alkali hydroxide in the production process, the purity of the core material is maintained because the acids and phosphoric esters in the core material are not affected much. .

Claims (1)

[Claims] 1. The core material is an organic acid or phosphate ester having 6 or more carbon atoms dissolved or dispersed in a hydrocarbon, natural oil (triglyceride), phthalate ester, adipate ester, or citric acid ester, which is liquid at room temperature, and gelatin microcapsules as a wall membrane substance.