KR100644905B1 - Powdered microcapsules and their preparation methods - Google Patents

Abstract

The present invention provides microcapsules capable of exhibiting excellent dispersibility. In addition, the present invention provides a method for producing a microcapsule comprising: (1) a first step of dispersing a hydrophobic material in an aqueous solution containing an anionic water-soluble polymer material; (2) a second step of preparing a slurry containing microcapsules having a resin film formed on the surface of a hydrophobic substance by blending an aminoaldehyde resin with the aqueous solution; And (3) a third step of carrying out the following step a) or step b); a) surface-treating the microcapsules recovered by removing the aqueous solution from the slurry with a surfactant; b) there is provided a method for producing the powdered microcapsules, which has a step of removing the aqueous solution from the slurry so that the content of the anionic water-soluble high molecular material to the powdered microcapsules is 0.01% by weight or less.

Powdered Microcapsules, Dispersible, Anionic Water Soluble Polymer, Hydrophobic Material, Aminoaldehyde Resin, Resin Coating, Surfactant

Description

Powdered microcapsules and its preparation method {POWDERED MICROCAPSULES AND THEIR PREPARATION METHODS}             

1 is a diagram showing a cross-sectional configuration of an electromotive force checker manufactured in Example 13. FIG.

The present invention relates to powdered microcapsules and a method for preparing the same. The present invention also relates to a reversible thermochromic coating and electromotive force checker using powdered microcapsules.

Microcapsules are granular bodies whose core material is coated on a wall material, and are widely used in various fields as medicines, cosmetics, pesticides, perfumes, adhesives, colorants, catalysts, and the like.

As a manufacturing method (microencapsulation method) of microcapsules, various methods, such as a chemical manufacturing method and a physical manufacturing method, have been proposed until now. As a chemical manufacturing method, a spray-drying method, a freeze drying method, a hot air fluidized bed method, etc. are known as physical manufacturing methods, such as an interfacial polymerization method, an in situ polymerization method, a coacervation method, etc., respectively.

In the physical preparation, microcapsules tend to aggregate and form secondary particles, whereas in chemical preparation, in particular, microcapsules can be obtained as a relatively well dispersed water (or aqueous solvent) dispersion. For this reason, the chemical manufacturing method can be said to be more advantageous than the physical manufacturing method in the use which can use a microcapsule as a water dispersion as it can preserve the favorable dispersibility as it is.

By the way, when water (solvent) is removed from the water dispersion obtained by the chemical manufacturing method, and microcapsules are used as powder (dry powder), problems of aggregation occur. That is, in the water dispersion, the dispersibility of the microcapsules is good, but if the microcapsules are taken out and dried, the microcapsules stick together to form aggregates. Once the aggregate is formed, significant energy (load) is required to disperse it. For this reason, it is very difficult to redisperse such powdered microcapsules in a solvent.

  In contrast, a method for producing powdered microcapsules without aggregation and destruction from an aqueous dispersion of microcapsules, wherein the aqueous dispersion of a higher fatty acid amide or a higher fatty acid metal salt is contained in an aqueous dispersion of microcapsules containing a hydrophobic liquid. A method of producing a powdered microcapsule, characterized in that the weight solid ratio of the high fatty acid amide or the higher fatty acid metal salt is mixed at 1: 0.05 to 1: 3, dried by freeze-vacuum drying or spray-drying. This is proposed (Japanese Patent Laid-Open No. 8-182927). According to this method, it is possible to produce powdered microcapsules with low aggregation.

However, even with the above method, the anti-agglomeration effect of the powdered microcapsules is insufficient, and further improvement is needed. In particular, when the powdered microcapsules are used as printing inks, it is also necessary to increase the dispersibility of the microcapsules in the oily medium.

  In addition, since the above method requires a drying step by a freeze vacuum drying method or a spray dry method, it can be said to be complicated as a process and also disadvantageous in terms of productivity, economy and the like.

On the other hand, in order to improve the dispersibility of the microcapsules, in the microcapsule manufacturing method of forming a resin film at the interface formed by dispersing the core material in the continuous phase of the liquid vehicle, needle-like resin pieces are fixed as the resin film on the outermost peripheral surface. A method for producing microparticle microcapsules, which is precipitated in a liquid vehicle continuous phase in advance and then fixed, has been proposed (Japanese Patent Laid-Open No. 5-212268). According to this production method, it is possible to obtain microparticle microcapsules in which aggregation and aggregation are prevented.

However, even in the microcapsules according to the above method, dispersibility is insufficient, and further improvement is required.

In addition, in the said method, it actually consists of two steps of the film forming process of a primary resin film, and the film forming process of a secondary resin film, and it is complicated as a process, and it can be said that it is disadvantageous also in terms of productivity, economy, etc.

In addition, in the above method, when the acicular fine resin fragments do not deposit on the outermost membrane and are present as primary particles, the particle size distribution of the solids becomes wider, and the voids between the particles become narrower, and thus, the filtration / drying takes a long time. There may be a need for it.

Accordingly, the main object of the present invention is to efficiently produce powdered microcapsules capable of exhibiting excellent dispersibility.

MEANS TO SOLVE THE PROBLEM As a result of earnest research in view of the prior art, it discovered that the said objective can be achieved by manufacturing powdered microcapsule by the manufacturing method which consists of a specific process, and finally came to complete this invention.

 That is, the present invention relates to the following powdered microcapsules and a preparation method thereof.

1. In the manufacturing method of the microcapsules,

(1) a first step of dispersing a hydrophobic substance in an aqueous solution containing an anionic water soluble high molecular substance;

(2) a second step of preparing a slurry containing microcapsules having a resin film formed on the surface of a hydrophobic substance by blending an aminoaldehyde resin with the aqueous solution; And

(3) Third step of carrying out step a) or step b) below

a) surface-treating the microcapsules recovered by removing the aqueous solution from the slurry with a surfactant;

b) A method for producing the powdered microcapsules, which comprises the step of removing the aqueous solution from the slurry such that the content of the anionic water-soluble high molecular substance in the powdered microcapsules is 0.01% by weight or less.

2. The process according to 1, wherein the surfactant in step a) of the third step is a cationic surfactant or a nonionic surfactant.

3. The process according to 1 above, wherein the aqueous solution is removed so that the content of the anionic water-soluble polymer substance in the microcapsules is 0.3% by weight or less.

4. The method according to the above 1, wherein in step a) or b) of the third step, the aqueous solution is removed by filtration or centrifugation.

5. The method according to item 1, wherein the pH of the slurry in step b) of the third step is adjusted to 2-4.

 6. Powdered microcapsules obtainable by the process according to any one of items 1 to 5.

 7. Printing ink which is made by dispersing powdered microcapsules according to item 6 in an oily medium.

8. As a coating film formed on a base material, the microcapsule containing a reversible thermochromic composition as a core material exists in the said coating film, and the particle size of the said microcapsule does not exceed 20 micrometers. Reversible thermochromic coating, characterized in that not.

9. The reversible thermochromic coating film according to item 8, wherein the glossiness (60 °) of the coating film is 60 or more.

10. The reversible thermochromic coating film according to item 8 or 9, wherein the discoloration temperature range is 4 ° C or less.

11. The reversible thermochromic coating film according to any one of items 8 to 10, wherein a color difference (ΔE * ab) before and after discoloration is 50 or more.

12. An electromotive force checker comprising at least a substrate, a conductive layer and a thermochromic layer, wherein said thermochromic layer consists of the reversible thermochromic coating film of any one of paragraphs 8 to 11. Electromotive force checker.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail based on embodiment.

1. Material used

(1) anionic water soluble high molecular substance

The polymer material is not particularly limited as long as it is anionic and soluble in water, and known or commercially available products can be used. For example, high molecular materials, such as maleic anhydride type, acrylic acid type, and sulfonic acid type, can be used. Examples of maleic anhydride include ethylene-maleic anhydride copolymer, methylvinyl ether-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, butadiene-maleic anhydride copolymer, isobutylene-maleic anhydride copolymer, and styrene Maleic anhydride copolymers, αmethylstyrene-maleic anhydride copolymers, and the like. Examples of the acrylic acid include polyacrylic acid, itaconic acid-acrylic acid copolymers, methacrylic acid-acrylic acid copolymers, and the like. Examples of the sulfonic acid system include polystyrene sulfonic acid, polyvinyl toluene sulfonic acid, styrene sulfonic acid-maleic anhydride copolymer, vinyl toluene sulfonic acid-maleic anhydride copolymer, and the like. These anionic water soluble high molecular materials can be used 1 type or in 2 or more types. In this invention, maleic anhydride type is especially preferable, and ethylene-maleic anhydride type copolymer is the most preferable among these.

(2) aminoaldehyde resin

The aminoaldehyde resin is not particularly limited as long as it can form the wall material of the powdered microcapsules according to the present invention, and a known or commercially available product can also be used. For example, urea-formaldehyde type resin, melamine-formaldehyde type resin, benzoguanamine resin, butylated melamine resin, butylated urea resin, urea-melamine type resin, etc. are mentioned. These aminoaldehyde resins can be used by 1 type (s) or 2 or more types. In this invention, melamine-formaldehyde type resin is especially preferable.

In addition, the degree of polymerization of these resins can be appropriately set according to the use of the final product, the kind of the polymer substance, and the like. For example, melamine-formaldehyde initial condensate can be suitably used as a melamine-formaldehyde resin. Such condensates are also known and can be prepared according to known methods.

(3) hydrophobic substances

The hydrophobic substance is to be the core substance in the powdered microcapsules of the present invention, and the hydrophobic substance is not particularly limited as long as it can be microencapsulated with the aminoaldehyde resin as the resin coating, and can be appropriately selected according to the use of the final product. Specifically, a hydrophobic substance can be suitably employed according to the use of pesticides, pigments, adhesives, pharmaceuticals, liquid crystal materials, adhesives, various wax oils and cosmetics.

In particular, when the powdered microcapsules are used as ink for printing, in addition to various colorants (inorganic pigments, organic pigments, dyes, etc.) as a hydrophobic substance, a colorant, a binder, a solvent, an ultraviolet absorber, a preservative, a drying accelerator, and an oxidation Additives, such as an inhibitor and an ultraviolet stabilizer, can also be used. Therefore, by combining these ink components, in addition to the ordinary printing ink, printing inks having various functions such as thermosetting type, ultraviolet curing type and electron beam curing type can also be produced.

In the present invention, a reversible thermochromic composition can be used as the hydrophobic material (center material). As a reversible thermochromic composition, a well-known thing or a commercial item can be used. For example, the composition which has three components of an electron-donating coloring organic compound, an electron accepting compound, and a sensitizer as an essential component is mentioned. Examples of the electron-donating color organic compound include triphenylmethane phthalide compounds, fluorane compounds, spiropyran compounds, indolinophthalide compounds, rhodamine lactam compounds, leucoolamine compounds, and the like. have. As an electron accepting compound, a phenolic compound, a thiourea derivative, an oxyaromatic carboxylic acid, carboxylic acid, its metal salt, etc. are mentioned, for example. As a sensitizer, high boiling alcohols, esters, acid amides, carboxylic acid, etc. are mentioned, for example. Thereby, the reversible thermochromic coating film of this invention can be obtained suitably.

(4) surfactant

As surfactant, it can select from a well-known thing or a commercial item suitably according to the property of a microcapsule, the use of a final product, etc. For example, as anionic surfactant, carboxylic acid type, such as fatty acid soap, sulfuric acid ester type, such as a long-chain alcohol sulfate, sulfonic acid type, such as an alkylbenzene sulfonate, and phosphate ester type, such as polyoxyethylene alkylphenyl ether phosphate ester, Etc; Examples of the cationic surfactant include amine salts such as long-chain primary amine salts, quaternary ammonium salts such as alkyltrimethylammonium salts, dialkyldimethylammonium salts and alkylpyridinium salts, and aliphatic amines such as polyoxyethylene alkylamines and alkylimides. Heterocyclic amines such as sleepy; As a nonionic surfactant, Ether type, such as polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene hardened castor oil, polyoxyethylene alkyl thioether, polyoxyethylene mono fatty acid ester, polyoxyethylene difatty acid ester Esters such as polyoxyethylene propylene glycol fatty acid ester, propylene glycol fatty acid ester, polyoxyethylene sorbitan mono fatty acid ester, glycerin mono fatty acid ester, sucrose fatty acid ester, alkanolamide type such as polyoxyethylene alkylamide, etc. N-alkylamino acid type, imidazoline type, etc. are mentioned as surfactant. Among these surfactants, nonionic surfactants (particularly HLB 3 to 9) or cationic surfactants are preferable in the present invention.

(5) other ingredients

In the said aqueous solution, an additive etc. can also be mix | blended in order to adjust pH of aqueous solution as needed in the range which does not prevent the effect of this invention.

2. Manufacturing method

As described above, the method for preparing the powdered microcapsules of the present invention

(1) a first step of dispersing a hydrophobic material in an aqueous solution containing an anionic water-soluble high molecular material,

(2) a second step of preparing a slurry containing microcapsules having a resin film formed on the surface of a hydrophobic substance by blending an aminoaldehyde resin with the aqueous solution; and

(3) Third step of carrying out step a) or step b) below

a) removing the aqueous solution from the slurry and surface treating the recovered microcapsules with a surfactant

b) removing the aqueous solution from the slurry so that the content of the anionic water-soluble high molecular substance in the powdered microcapsules is 0.01% by weight or less.

(1) First step

In the first step, the hydrophobic material is dispersed in an aqueous solution containing an anionic water soluble high molecular material. The concentration of the anionic water-soluble polymer substance in the aqueous solution may be appropriately set according to the type of the anionic water-soluble polymer substance to be used, but is usually about 0.1 to 20% by weight, preferably 2 to 8% by weight.

The amount of hydrophobic material used may be appropriately set depending on the purpose of the final product and the type of hydrophobic material. For example, when using the powdered microcapsules as printing ink, it is usually set in the range of about 50 to 120 parts by weight, preferably 70 to 90 parts by weight based on 100 parts by weight of the aqueous solution.

The dispersion method is not particularly limited as long as the hydrophobic material can be uniformly dispersed, and can be carried out according to a known method. For example, it can disperse | distribute using well-known stirring apparatuses, such as a homomixer, a homogenizer, and a dissolver. In addition, dispersion in this invention is a concept containing not only dispersion but an emulsion. Therefore, it can also be set as the O / W type emulsion formed by disperse | distributing a hydrophobic substance.

In this invention, after disperse | distributing a hydrophobic substance, you may adjust pH according to the kind of aminoaldehyde resin etc. which are mix | blended in a 2nd process. For example, when using melamine-formaldehyde-type resin etc. as an aminoaldehyde resin, what is necessary is just to adjust the pH of the said aqueous solution to about 3.5-6.5.

(2) second process

In the second step, an aminoaldehyde resin is blended with the aqueous solution to prepare a slurry containing microcapsules in which a resin film is formed on the surface of a hydrophobic substance.

Although the compounding quantity of aminoaldehyde resin may be changed suitably according to the kind of aminoaldehyde resin to be used, desired film thickness, etc., about 1-25 weight part is preferable with respect to 100 weight part of aqueous solutions (dispersion liquid) after disperse | distributing a hydrophobic substance normally Preferably it is 10-15 weight part.

(3) Third process

In a 3rd process, following process a) or process b) is performed.

a) removing the aqueous solution from the slurry and surface treating the recovered microcapsules with a surfactant

b) removing the aqueous solution from the slurry such that the content of the anionic water-soluble high molecular material in the powdered microcapsules is 0.01% by weight or less.

Process a)

In step a), the microcapsules recovered by removing the aqueous solution from the slurry are surface treated with a surfactant.

First, the aqueous solution is removed from the slurry prepared in the second step to recover the microcapsules. The method of removing the aqueous solution is not particularly limited as long as the microcapsules can be recovered, and can be carried out according to a known solid-liquid separation method. As a solid-liquid separation method, filtration, centrifugation, etc. can be employ | adopted suitably, for example. After removing the said aqueous solution, you may wash with water as needed, or may disperse in water, and perform the same solid-liquid separation.

In process a), it is preferable to remove the said aqueous solution so that content of the anionic water-soluble polymer substance with respect to a microcapsule (solid content) may be 0.3 weight% or less. Therefore, you may repeat said solid-liquid separation and water washing as needed until it becomes the said content.

The microcapsules are then surface treated with a surfactant. The treatment method is not particularly limited as long as the surfactant can be imparted to the surface of the microcapsule. Preferably, the method can be carried out by dispersing and stirring the microcapsule in an aqueous solution containing the surfactant. Although the density | concentration of surfactant in this aqueous solution can be set suitably according to the kind etc. of surfactant used, Usually, about 0.001 to 5 weight%, Preferably you may be 0.01 to 0.5 weight%. If the concentration of the surfactant is too low, the surfactant cannot be sufficiently provided to the microcapsule surface. If the concentration is too high, it may be difficult to obtain the powdered microcapsules in a dry state.

  In addition, the amount (throughput) of the microcapsules (solid content) with respect to the aqueous solution is not particularly limited as long as stirring is possible, but is usually about 1 to 100 parts by weight, preferably 10 to 30 parts by weight, based on 100 parts by weight of the aqueous solution. Do it.

The microcapsules may be stirred in an aqueous solution containing a surfactant, followed by solid-liquid separation according to a conventional method. Moreover, in this invention, you may repeat surface treatment and solid-liquid separation by said surfactant as needed. After solid-liquid separation, you may dry as needed. As a drying method, a well-known method may be employ | adopted and any of natural drying or forced drying may be sufficient.

Process b)

In step b), the aqueous solution is removed from the slurry so that the content of the anionic water-soluble high molecular substance in the powdered microcapsules is 0.01% by weight or less, preferably 0.005% by weight or less. When the content exceeds 0.01% by weight, the powdered microcapsules are easily aggregated as they are. The method of removing the aqueous solution is not particularly limited as long as the content can be controlled, and can be carried out according to a known solid-liquid separation method. As a solid-liquid separation method, filtration, centrifugal separation, etc. can be employ | adopted suitably, for example. After removing the aqueous solution, washing with water or dispersion in water, if necessary, can be carried out in the same solid-liquid separation. In addition, you may repeat each operation of these solid-liquid separation or water washing as needed.

After solid-liquid separation or water washing, you may dry as needed. A drying method may employ | adopt a well-known method, for example, any of natural drying or forced drying may be sufficient.

In process b), it is preferable to adjust pH of a slurry to 2-4 beforehand. That is, it is preferable to control the pH of the slurry after microcapsules are produced in the range of 2-4. By controlling the pH to this range, the above-mentioned solid-liquid separation (especially filtration, centrifugation, etc.) becomes easy. As a result, even a slurry prepared at any pH can be easily liquid-liquid separated. As a pH adjuster, a well-known thing can be used. For example, inorganic acids such as hydrochloric acid and phosphoric acid, organic acids such as acetic acid, malic acid, tartaric acid and citric acid, and, in some cases, alkalis such as ammonia, sodium hydroxide, potassium hydroxide and triethanolamine can also be used.

3. Powdered microcapsules and printing inks

The powdered microcapsules of the present invention can be obtained, for example, by the production method of the present invention. Although the average particle diameter of the powdered microcapsules varies depending on the use of the final product and the like, it can usually be controlled in the range of about 1 to 100 µm, preferably 2 to 10 µm.

The powdered microcapsules according to the present invention are difficult to aggregate and may exist in the state of almost primary particles. Moreover, even if it is temporarily aggregated, it can become a state of primary particle easily. The dispersibility of the powdered microcapsules is generally 10 μm or less by grinding gauge.

In particular, the powdered microcapsules of the present invention exhibit excellent dispersibility even in an oil-based medium, and thus can be efficiently used, for example, as printing masters, as well as various master batches, various paints, and the like.

 When using as a printing ink, printing ink can be manufactured according to the manufacturing method of a well-known printing ink except using the powdered microcapsules obtained by this invention as microcapsules. For example, printing ink in which the powdered microcapsules are dispersed in an oily medium can be prepared by mixing and stirring the powdered microcapsules using a core material containing a colorant with an organic solvent or the like. In addition, this printing ink can be printed on paper, an inorganic material, a resin sheet, or the like according to known printing methods such as screen printing, offset printing, and gravure printing.

4. Reversible thermochromic coating

The reversible thermochromic coating film of the present invention is a coating film formed on a substrate, wherein microcapsules containing a reversible thermochromic composition as a central substance are present in the coating film, and the particle size of the microcapsules does not exceed 20 μm. It is characterized by.

  As a base material, if the coating film of this invention can be formed, it will not specifically limit. For example, metals, alloy materials, ceramics, plastics, glass, paper, fibers, or the like or composite materials thereof can be used.

The composition of the microcapsules is not particularly limited as long as it includes a reversible thermochromic composition as a core material. As such a composition itself, a well-known ink can be used, for example, the composition which has three components, such as an electron-donating color organic compound, an electron accepting compound, and a sensitizer, as an essential component can be used.

Moreover, the wall material of a microcapsule is not limited, either, Usually, it can form by a resin film. Although the kind is not limited as resin in a resin film, In particular, an aminoaldehyde resin can be used suitably. As aminoaldehyde resin, the various things mentioned above can be employ | adopted.

Such microcapsules are preferably used microcapsules obtained by the production method of the present invention. Especially as a coating film of this invention, particle size is adjusted in the range which particle size does not exceed 20 micrometers, Preferably it is about the range of particle size about 1-10 micrometers. Particle size adjustment is unnecessary when the powdered microcapsules obtained by the above-mentioned production method are already constituted with a particle diameter of 20 µm or less. On the other hand, when the powdered microcapsules obtained by the above-described production method include those having a particle size of more than 20 µm, those having more than 20 µm may be removed by a known classification method.

The glossiness (60 degrees) of the coating film of this invention is 60 or more normally, Preferably it is 80 or more. In addition, the discoloration temperature range of a coating film is 4 degrees C or less normally, Preferably it is 3.5 degrees C or less. Moreover, the color difference ((DELTA) E * ab) before and after discoloration of the coating film of this invention is 50 or more normally, Preferably it is 70 or more. By having 1 or 2 or more of these properties, more excellent thermochromic performance, for example, more excellent glossiness, thermal response, color density, sharpness of discoloration, etc. can be obtained.

The coating film of this invention can be formed, for example by apply | coating said printing ink of this invention on a base material by a well-known method. Such a reversible thermochromic coating film can be applied to electromotive force checkers, for example. That is, the present invention includes an electromotive checker comprising at least a substrate, a conductive layer and a thermochromic layer, wherein the thermochromic layer comprises the reversible thermochromic coating film of the present invention.

The electromotive force checker of this invention can employ | adopt a well-known element other than using this invention coating film as a thermochromic layer. For example, a film-like substrate such as polyimide film or polyethylene terephthalate (PET) is used as the substrate, and a conductive layer formed of a conductive ink is laminated on the surface of the substrate, and a thermochromic layer is formed on the back surface of the substrate. What is necessary is just to form by the coating film of this invention. In this case, as needed, you may interpose the thermochromic layer which does not discolor by heat between a board | substrate and a thermochromic layer. If necessary, a protective layer made of a transparent resin or the like can be provided on the thermochromic layer. Although the thickness of each of these layers may be set suitably according to the purpose of use of a final product, etc., what is necessary is just to determine within the range of about 0.01-1 mm normally. In the electromotive force checker of the present invention, by bringing the electrode of the battery into contact with the contact portion of the conductive layer, heat generated in the conductive layer is transferred to the thermochromic layer, and discoloration of the thermochromic layer occurs. In this way, the electromotive force of the battery is specified by the change of the thermochromic layer (in some cases, the color difference with the thermochromic layer). More specifically, it is also possible to quantitatively measure the electromotive force of the battery to be measured depending on the magnitude of the area of the discolored region of the thermochromic layer set in relation to the electromotive force. The electromotive force checker of the present invention is useful as, for example, a battery electromotive force checker such as a battery.

An Example and a comparative example are shown to the following, and the characteristic of this invention is more clear. However, this invention is not limited to these Examples.

Example 1

(1) Preparation of microcapsule slurry

First, an aminoaldehyde resin was prepared. 6 weight part of melamine was mix | blended with 14 weight part of 37 weight% formaldehyde solutions, and it melt | dissolved at 60 degreeC by heating. After dissolution, cooling to room temperature gave a melamine-formaldehyde initial condensate.

On the other hand, an ethylene-maleic anhydride copolymer (manufactured by D LAND Chemical Co., Ltd.) was used as the anionic water-soluble high molecular substance, which was dissolved in water to prepare a 5% by weight aqueous solution, and further adjusted to pH 4.0.

As a hydrophobic substance, a mixture of 2 parts by weight of crystal violet lactone and 4 parts by weight of bisphenol A was dissolved in 70 parts by weight of stearyl alcohol, and the mixture was mixed with the aqueous solution and stirred with a homomixer to form a median diameter of 3 µm O /. W-type emulsion was prepared.

After adding 20 weight part of said melamine-formaldehyde initial condensates with stirring with respect to 100 weight part of this emulsion, it heated up at 60 degreeC and continued stirring for further 2 hours. Then, the microcapsule slurry was obtained by stirring for 1 hour after turning on a cooler.

(2) Recovery of Powdered Microcapsules

200 g of the slurry was suction filtered through Buchnerot to obtain a wet cake. Subsequently, the cake was introduced into 100 g of water, followed by suction filtration to obtain a cake in the same manner. This cake had a weight of 120 g and a water content of 40%. Furthermore, this cake was thrown into a mixed liquid of 500 g of water and 0.1 g of polyoxyethylene dodecylamine (made by "Nimine L-202" Nihon Holding) to be reslurried. The slurry thus obtained was suction filtered in the same manner as above to recover microcapsules, and then dried to obtain powdered microcapsules. As a result of observing this powdered microcapsules with a scanning electron microscope, it was confirmed that the microcapsules existed in the state of almost primary particles without aggregation.

(3) Preparation of ink for printing

Printing inks were prepared using the powdered microcapsules. First, 40 parts by weight of the microcapsules were mixed and stirred with 100 parts by weight of an epoxy resin (manufactured by Epicoat 828 Yucca Shell) to obtain an ink main body. Subsequently, 25 weight part of hardening | curing agents (made by "Epicure U" yucca shell) were mixed and stirred on this subject, and the printing ink was obtained.

(4) printing by printing ink

Using this printing ink, a printing film was formed by printing on a white plate using a 200 mesh silk screen and heating at 120 ° C. for 30 minutes. There was no clogging of the screen during printing, and the formed coating film surface was very smooth. From this, it can be seen that the microcapsules in the printing ink have excellent dispersibility.

Example 2

Printing inks were prepared using the powdered microcapsules obtained in Example 1. First, 25 parts by weight of the microcapsules, 1 part of 2,4-diethyl thioxanthone, 40 parts by weight of an aromatic urethane acrylate ("Alonics M-1100" manufactured by Toago Seika Chemical Co., Ltd.) and neopentyl glycol diacrylate The ink for printing was obtained by mixing and stirring to 30 weight part.

Using this printing ink, after printing on a polyethylene terephthalate white film using a 200 mesh silk screen, it was irradiated with ultraviolet rays (irradiation with a high pressure mercury lamp of 120 W / cm, irradiation distance 10 cm, conveyor speed 10 m / min). To form a cured coating film. There was no clogging of the screen during printing, and the formed coating film surface was very smooth. From this, it can be seen that the microcapsules in the printing ink have excellent dispersibility.

Example 3

First, using the microcapsule slurry obtained in Example 1 (1), powdered microcapsules were prepared.

First 200 g of the microcapsule slurry was suction filtered through Buchnerot to obtain a wet cake. Subsequently, the cake was introduced into 100 g of water, followed by suction filtration to obtain a cake in the same manner. This cake had a weight of 120 g and a water content of 40%. Furthermore, this cake was thrown into a mixed liquid of 500 g of water and 0.8 g of polyoxyethylene nonylphenyl ether ("non-ion NS-204.5" Nihon Holding), and then reslurried. The slurry thus obtained was suction filtered in the same manner as above to recover microcapsules, and then dried to obtain powdered microcapsules. As a result of observing this powdered microcapsule with a scanning electron microscope, it was confirmed that it was in a state of almost primary particles without aggregation.

Using the obtained powdered microcapsules, printing inks were prepared in the same manner as in Example 1 (3). Using this printing ink, silkscreen printing was performed on a white plate in the same manner as in Example 1 (4). There was no clogging of the screen during printing, and the formed coating film surface was very smooth. From this, it can be seen that the microcapsules in the printing ink have excellent dispersibility.

Example 4

A printing ink was prepared in the same manner as in Example 2 except that the powdered microcapsules obtained in Example 3 were used. Using this printing ink, silkscreen printing was performed on the polyethylene terephthalate white film in the same manner as in Example 2, and then a cured coating film was formed by ultraviolet irradiation. There was no clogging of the screen during printing, and the formed coating film surface was very smooth. From this, it can be seen that the microcapsules in the printing ink have excellent dispersibility.

Comparative Example 1

200 g of the microcapsule slurry obtained in Example 1 was suction filtered through Buchnerot to obtain a wet cake. Subsequently, the cake was introduced into 100 g of water, followed by suction filtration to obtain a cake in the same manner. This cake had a weight of 120 g and a water content of 40%. This was dried to obtain powdered microcapsules. The microcapsules were observed with a scanning electron microscope, and as a result, numerous aggregates were formed.

Using this powdered microcapsules, printing ink was prepared in the same manner as in Example 1 (3). Using the obtained printing ink, silkscreen printing was carried out on the white plate in the same manner as in Example 1 (4), and then heated to form a printed coating film. Clogging of the screen during printing occurred, and the presence of coarse particles was confirmed on the formed coating film surface.

Comparative Example 2

After using the powdered microcapsules of Comparative Example 1 and silkscreen printing on a white film made of polyethylene terephthalate in the same manner as in Example 2, a cured coating film was formed by ultraviolet irradiation. Clogging of the screen during printing occurred, and the presence of coarse particles was confirmed on the formed coating film surface.

Test Example 1

The remaining amount of the anionic water-soluble polymer substance of the powdered microcapsules in Examples and Comparative Examples, the properties of the powdered microcapsules, the dispersibility of the powdered microcapsules in the printing ink, the state of the printing coating film, and the like were investigated. . The results are shown in Table 1. In addition, each physical property was measured with the following method, respectively.

(1) Residual amount of anionic water-soluble high molecular substance

Each powdered microcapsules were reslurried with water to a solid content concentration of 40% by weight, and the content of the anionic water-soluble high molecular substance in the slurry was measured by GPC (gel permeation chromatography). As a measuring apparatus, "GPC chromatography GULLIVER series" Japanese spectroscopy (use column: TOSOHTSK-GEL G4000 PW) was used.

(2) Powdered Microcapsule Dispersibility

The grind gauge (100 micrometers) was used, the scale of the location where the microcapsule particle in the medium was confirmed was read, and the dispersion degree was investigated.

(3) State of coating film

The coating film surface was visually observed. (Circle) that coarse particle was not recognized by the naked eye, and what made coarse particle visible with coarse particle were made into x.

Residue in Powder * (% by weight) Presence of surfactant SEM observation of powder state Dispersibility ** Coating state Example 1 0.08 U Almost primary particles 10μm or less ○ Example 2 0.08 U Almost primary particles 10 μm or less ○ Example 3 0.09 U Almost primary particles 10μm or less ○ Example 4 0.09 U Almost primary particles l0μm or less ○ Comparative Example 1 0.08 radish Forming aggregates 100 μm or more × Comparative Example 2 0.08 radish Forming aggregates l00μm or more ×

* Residual amount of anionic water-soluble high molecular substance

** Dispersibility of Powdered Microcapsules

As is clear from Table 1, it is understood that the powdered microcapsules according to the present invention exist in the form of almost primary particles and exhibit excellent dispersibility even in printing inks.

Example 5

(1) Preparation of microcapsule slurry A

First, an aminoaldehyde resin was prepared. 6 weight part of melamine was mix | blended with 14 weight part of 37 weight% formaldehyde solutions, and it melt | dissolved at 60 degreeC by heating. After dissolution, cooling to room temperature gave a melamine-formaldehyde initial condensate.

On the other hand, ethylene-maleic anhydride copolymer (manufactured by Di-Land Chemical Co., Ltd.) was used as the anionic water-soluble high molecular substance, which was dissolved in water to prepare a 5% by weight aqueous solution, and further adjusted to pH 4.0. As a hydrophobic substance, 70 parts by weight of a synthetic perfume (Nisshin Co., Citrus) was blended with the aqueous solution, and stirred with a homomixer to prepare an O / W emulsion having a median diameter of 3 μm.

After adding 20 weight part of said melamine-formaldehyde initial condensates with stirring with respect to 100 weight part of this emulsion, it heated up at 60 degreeC and continued stirring for further 2 hours. Thereafter, after cooling, the mixture was stirred for 1 hour to obtain a microcapsule slurry A.

(2) Preparation of Microcapsule Slurry B

A microcapsule slurry B was obtained in the same manner as in the slurry A except that vinyltoluenesulfonic acid-maleic anhydride copolymer (manufactured by Kanebo NSC Corporation) was used in place of the ethylene-maleic anhydride copolymer as an anionic water-soluble high molecular material.

Example 6

200 g of the slurry A was adjusted to 3 using a 10 wt% aqueous hydrochloric acid solution. Thereafter, the slurry was suction filtered through Buchnerot, whereby a wet cake could be easily obtained without any problem. Furthermore, the said cake was made to flow in 100 g of water, and the operation of carrying out suction filtration was repeated three times. The resulting cake was heated to dry at 50 ° C. to obtain powdered microcapsules. As a result of observing this microcapsule with a scanning electron microscope, it was confirmed that it existed in the state of almost primary particle, without aggregation.

Example 7

200 g of the slurry B was adjusted to 3 using a 10 wt% aqueous hydrochloric acid solution. Thereafter, the slurry was centrifuged to settle the microcapsules. The separated supernatant was removed, and the same amount of water was further added, followed by centrifugation in the same manner. Furthermore, water addition and centrifugation were repeated twice. The precipitate obtained was heated to 50 ° C. to obtain powdered microcapsules. As a result of observing this microcapsule with a scanning electron microscope, it was confirmed that it existed in the state of almost primary particle, without aggregation.

Comparative Example 3

200 g of the slurry A was adjusted to 3 using a 10 wt% aqueous hydrochloric acid solution. Thereafter, the slurry was suction filtered through Buchnerot, whereby a wet cake could be easily obtained without any problem. The obtained cake was heated to 50 DEG C without washing with water to obtain powdered microcapsules. This microcapsules are agglomerated and difficult to touch by hand.

Comparative Example 4

200 g of the slurry B was adjusted to 3 using a 10 wt% aqueous hydrochloric acid solution. The slurry was then centrifuged to settle the microcapsules. The sediment obtained was heated to 50 ° C. without washing with water to obtain powdered microcapsules. This microcapsules are agglomerated and difficult to touch by hand.

Test Example 2

The content of the anionic water-soluble high molecular substance of the powdered microcapsules obtained in Examples 6 and 7, and Comparative Examples 3 and 4 was investigated. In the measurement method, the powdered microcapsules were reslurried with water to have a solid content of 40% by weight, and the content of the anionic water-soluble high molecular substance (ethylene-maleic anhydride copolymer) in the slurry was analyzed by GPC (gel permeation chromatography). Quantitative. As a GPC apparatus, "GPC chromatography GULLIVER series" Nihon Bunko Co., Ltd. (use column: TOSOH TSK-GEL G 4000PW) was used. These results are shown in Table 2 together with the state of the powdered microcapsules.

Residue in Powder * (% by weight) SEM observation of powder state Example 6 0.005 Almost primary particles Example 7 0.004 Almost primary particles Comparative Example 3 0.09 congelation Comparative Example 4 0.02 congelation

 * Residual amount of anionic water-soluble high molecular substance

As is apparent from the results in Table 2, the powdered microcapsules of Examples 6 and 7 having a content of anionic water-soluble high molecular weight of the powdered microcapsules by 0.01% by weight or less were prepared by the use of the primary particles. While present in the form, it can be seen that in Comparative Examples 3 and 4 in which the content is more than 0.01% by weight, agglomeration occurs, and the dispersibility is inferior to that of the examples.

Example 8

(1) Preparation of Powdered Microcapsules A

200 g of the microcapsule slurry obtained in Example 1 was adjusted to 3 using a 10 wt% aqueous hydrochloric acid solution. Thereafter, the slurry was suction filtered through Buchnerot, whereby a wet cake could be easily obtained. Further, 100 g of water was introduced into the cake, followed by repeated suction filtration three times. The cake obtained was heated to 50 ° C. to obtain powdered microcapsules. As a result of observing this microcapsule with a scanning electron microscope, it was confirmed that it existed in the state of almost primary particle, without aggregation. The residual amount of the anionic water-soluble high molecular substance of the powdered microcapsules was measured in the same manner as in Test Example 1, and found to be 0.005% by weight.

(2) Preparation of Powdered Microcapsules B

200 g of the microcapsule slurry obtained in Example 1 was suction filtered through Buchnerot to obtain a wet cake. 100 g of water was made to flow on this cake, and suction filtration was performed continuously. The cake obtained had a weight of 120 g and a water content of 40%. Furthermore, this cake was reslurried in 500 g of water and 0.1 g of polyoxyethylene dodecylamine (made by "Nimine L-202" Nihon holding). The resulting slurry was filtered and dried to obtain powdered microcapsules. As a result of observing this microcapsule with a scanning electron microscope, it was confirmed that it existed in the state of almost primary particle, without aggregation. The residual amount of the anionic water-soluble high molecular substance of the powdered microcapsules was measured in the same manner as in Test Example 1, and found to be 0.08% by weight.

(3) Preparation of Powdered Microcapsules C

200 g of the microcapsule slurry obtained in Example 1 was suction filtered through Buchnerot to obtain a wet cake. Furthermore, 100 g of water was flowed into this cake, and suction filtration was performed subsequently. The cake obtained had a weight of 120 g and a water content of 40%. The microcapsules were observed with a scanning electron microscope to confirm that aggregates were formed. The residual amount of the anionic water-soluble polymer substance in the powdered microcapsules was measured in the same manner as in Test Example 1, and found to be 0.08% by weight.

Example 9

40 parts by weight of the powdered microcapsules A of Example 8 and 100 parts by weight of an epoxy resin (manufactured by "Epicoat 828" Yucca Shell) were mixed and stirred to obtain an ink main body. Furthermore, 25 weight part of hardening | curing agents (made by "Epicure U" yucca shell) were mixed and stirred on this subject, and the printing ink was obtained. This ink was printed on a white plate using a 150 mesh silk screen, and heated at 120 ° C. for 30 minutes to obtain a printed coating film. The coating film surface had a very smooth surface, did not block the screen at the time of printing, and was very good in dispersibility.

Example 10

40 parts by weight of the powdered microcapsules B of Example 8 and 100 parts by weight of an epoxy resin (manufactured by Epicoat 828 oil car shell) were mixed and stirred to obtain an ink main body. Furthermore, 25 weight part of hardening | curing agents (made by "Epicure U" yucca shell) were mixed and stirred on this subject, and the printing ink was obtained. This ink was printed on a white plate using a 150 mesh silk screen, and heated at 120 ° C. for 30 minutes to obtain a printed coating film. The coating film surface had a very smooth surface, had no clogging of the screen during printing, and had very good dispersibility.

Example 11

25 parts by weight of the powdered microcapsules A of Example 8 1 part by weight of 2,4-diethyl thioxanthone, 40 parts by weight of an aromatic urethane acrylate ("Alonics M-1100" manufactured by Toago Seikagaku Co., Ltd.) and Neo 30 weight part of pentyl glycol diacrylates were mixed and stirred, and the printing ink was obtained. This ink was printed on a white PET (polyethylene terephthalate) film using a 200 mesh silk screen, and irradiated with ultraviolet light at a irradiation distance of 10 cm and a conveyor speed of 10 m / min using a high pressure mercury lamp of 120 W / cm to obtain a cured coating film. did. The coating film surface had a very smooth surface, had no clogging of the screen during printing, and had very good dispersibility.

Example 12

25 parts by weight of the powdered microcapsules B of Example 8 1 part by weight of 2,4-diethyl thioxanthone, 40 parts by weight of an aromatic urethane acrylate ("Alonics M-1100" manufactured by Toago Seikagaku Co., Ltd.) and neo 30 weight part of pentyl glycol diacrylates were mixed and stirred, and the printing ink was obtained. This ink was printed on a white PET film using a 200 mesh silk screen, and was irradiated with ultraviolet light at an irradiation distance of 10 cm and a conveyor speed of 10 m / min using a high-pressure mercury lamp of 120 W / cm to obtain a cured coating film. The coating film surface had a very smooth surface, did not block the screen at the time of printing, and was very good in dispersibility.

Example 13

Using the printing ink prepared in Example 11, the electromotive checker for batteries was produced by printing on the surface of a film-form substrate made of PET having a conductive layer formed on its back surface so as to obtain a thermochromic layer having a thickness of 0.5 mm. The outline of the structure is shown in FIG. In the checker, a thermochromic layer 3 which is not discolored by heat, and a thermochromic layer 4 are sequentially formed on the surface of the film-like substrate 1 on which the conductive layer 2 is formed on the rear surface thereof. . The battery remaining amount of the battery was checked by contacting the contact portions 5 and 6 of the checker with the battery electrode, and it was confirmed correctly after about 10 seconds.

Example 14

Using the printing ink prepared in Example 12, printing was carried out on the same substrate as in Example 13 so that a thermochromic layer having a thickness of 0.5 mm was obtained, and an electromotive force checker for batteries having the same configuration as in Example 13 was produced. Using this, the battery remaining amount of the battery was checked in the same manner as in Example 13, and was confirmed accurately after about 10 seconds.

Comparative Example 5

40 parts by weight of powdered microcapsules C and 100 parts by weight of an epoxy resin (made by Epicoat 828) were obtained by mixing and stirring to obtain an ink main body. Furthermore, 25 weight part of hardening | curing agents (made by "Epicure U" yucca shell) were mixed and stirred on this subject, and the printing ink was obtained. This ink was printed on a white plate using a 200 mesh silk screen, and heated at 120 ° C. for 30 minutes to obtain a printed coating film. The presence of aggregates of microcapsules on the surface of the coating film was visually observed.

Comparative Example 6

25 parts by weight of the above-mentioned powdered microcapsules C 1 part by weight of 2,4-diethyl thioxanthone, 40 parts by weight of an aromatic urethane acrylate ("Alonics M-1100" manufactured by Toago Seika Chemical Co., Ltd.) and neopentyl glycol 30 weight part of diacrylates were mixed and stirred, and the printing ink was obtained. This ink was printed on a white PET film using a 200 mesh silk screen and irradiated with ultraviolet light at a irradiation distance of 10 cm and a conveyor speed of 10 m / min using a high-pressure mercury lamp of 120 W / cm to obtain a cured coating film. It was observed visually that aggregates of microcapsules existed on the surface of the coating film.

Comparative Example 7

Using the printing ink prepared in Comparative Example 6, a thermochromic layer having a thickness of 0.5 mm was printed on the same substrate as in Example 13 to produce an electromotive force checker for dry batteries having the same structure as in Example 13. Using this, the battery remaining amount of the battery was examined in the same manner as in Example 13, and it took about 13 seconds until the battery remaining amount could be accurately confirmed.

Test Example 3

The dispersibility of the powdered microcapsules used in Examples 9 to 12 and Comparative Examples 5 to 6 and the properties of the printed coating film were investigated, respectively. The results are shown in Table 3.

  Dissipation ** Coating state Discoloration temperature range (℃) Glossiness (60 °) Color difference △ E * ab before and after color change Example 9 10μm or less ○ 3.5 87 75 Example 10 10μm or less ○ 3.5 85 74 Example 11 10μm or less ○ 3.0 66 74 Example 12 10μm or less ○ 3.0 63 74 Comparative Example 5 40 μm × 4.5 58 35 Comparative Example 6 40 μm X 4.1 18 29

** Dispersibility of Powdered Microcapsules

In addition, the measuring method of each physical property of Table 3 was implemented with the following method.

(1) Powdered Microcapsule Dispersibility

Investigation was carried out in the same manner as in Example 1.

(2) state of coating film

Investigation was carried out in the same manner as in Example 1.

(3) discoloration temperature range

The coating film is heated from 20 ° C to 60 ° C at a heating rate of 0.5 ° C / sec, and the chromaticity of the surface of the coating film is measured with an L * a * b * colorimeter every 0.5 ° C. Subsequently, the color difference ΔE * ab between the coating film surface at the start and the heated coating film surface is calculated, respectively, and the temperature range from the temperature at which the value of the color difference becomes 2 or more to the temperature at which the value of the color difference starts to stabilize is discolored temperature. I made a range.

In addition, the color difference (DELTA) E * ab was calculated | required by the following formula for the measurement of chromaticity L * a * b * using the color difference meter (CR-300 "Minolta).

ΔE * ab = {(ΔL *) ² } + (Δa *) ² + (Δb *) ² } ^1/2

(4) glossiness

The measurement angle measured using the glossmeter (the "IG-310" Horiba Corporation make) of 60 degrees -60 degrees.

(5) color difference before and after discoloration

The color difference between the chromaticity L * a * b * at the time of color development of the coating film surface, and L * a * b * at the time of bleaching was calculated | required. The measurement of chromaticity was performed by the same method as the case of said (3).

Since the manufacturing method of this invention provides surfactant to a microcapsule surface by a specific process, the powdered microcapsule excellent in dispersibility can be obtained. In particular, since the powdered microcapsules exist substantially as primary particles in the oil medium, and exhibit good dispersibility, they can be suitably used for conventional applications such as printing inks and various paints.                     

In addition, the powdered microcapsules can be produced by a relatively simple process in the production method of the present invention, which is suitable for production on the industrial scale of the powdered microcapsules, and also exhibits excellent productivity, economy and the like.

Since the reversible thermochromic coating film of this invention contains the specific microcapsule which consists essentially of a primary particle, it can exhibit the outstanding thermochromic performance, etc. In particular, excellent effects can be obtained in glossiness, thermochromic properties (thermal responsiveness), color density, sharpness of discoloration, and the like. Such a coating film is useful as an electromotive force checker used for a battery etc., for example.

Claims (12)

In the manufacturing method of the microcapsules, (1) a first step of dispersing a hydrophobic substance in an aqueous solution containing an anionic water soluble high molecular substance; (2) a second step of preparing a slurry containing microcapsules having a resin film formed on the surface of a hydrophobic substance by blending an aminoaldehyde resin with the aqueous solution; And (3) Third step of carrying out step a) or step b) below a) surface-treating the microcapsules recovered by removing the aqueous solution from the slurry with a surfactant; b) A method for producing the powdered microcapsules, which comprises the step of removing the aqueous solution from the slurry such that the content of the anionic water-soluble high molecular substance in the powdered microcapsules is 0.01% by weight or less. The method of claim 1, A method for producing powdered microcapsules, wherein the surfactant in step a) of the third step is a cationic surfactant or a nonionic surfactant. The method of claim 1, The process for producing powdered microcapsules according to step a) of the third step, wherein the aqueous solution is removed so that the content of the anionic water-soluble polymer substance in the microcapsules is 0.3% by weight or less. The method of claim 1, The process for producing powdered microcapsules in step a) or step b) of the third step, wherein the aqueous solution is removed by filtration or centrifugation. The method of claim 1, The manufacturing method of the powdered microcapsule which adjusts pH of the slurry in the process b) of 3rd process to 2-4. delete A printing ink comprising powdered microcapsules obtained by the manufacturing method according to any one of claims 1 to 5, (1) The wall material of the powdered microcapsules is an aminoaldehyde resin, (2) the core material of the powdered microcapsules is a hydrophobic material, (3) The ink for printing, wherein the dispersibility of the powdered microcapsules is 10 µm or less in terms of a grind gauge. As a coating film formed on a base material, the powdered microcapsules obtained by the manufacturing method according to claim 1 containing a reversible thermochromic composition as a central substance are present in the coating film, and the particle size of the microcapsules is 1 Reversible thermochromic coating, characterized in that ~ 10 μm. The method of claim 8, A reversible thermochromic coating with a glossiness of 60 ° or more. The method according to claim 8 or 9, Reversible thermochromic coating film with discoloration temperature range of 4 ℃ or less. The method according to claim 8 or 9, A reversible thermochromic coating film having a color difference (ΔE * ab) of 50 or more before and after discoloration. An electromotive force checker comprising at least a substrate, a conductive layer and a thermochromic layer, wherein the thermochromic layer is made of the reversible thermochromic coating film according to any one of claims 8 to 11. Electromotive checkers.

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