KR100431584B1 - A Preparation Method of Thermostable Microcapsules Containing Phase Change Materials And Articles Including Microcapsules Prepared Thereby - Google Patents

Abstract

The present invention relates to a method for preparing a microcapsule using a polymer polymerized from a monomer having an alkyl group having 8 to 18 carbon atoms as a phase change material, and an article including the microcapsules prepared accordingly. The microcapsule of the present invention is a polymerizable monomer phase change having an alkyl group having 0 to 70% by weight of a nonpolar organic solvent and 8 to 18 carbon atoms in a solution in which the surfactant is dissolved at 0.2 to 10 parts by weight with respect to 100 parts by weight of water. 10 to 50 parts by weight of an organic phase consisting of 10 to 90% by weight of the substance and 10 to 50% by weight of the compound having two or more isocyanate groups and emulsified under stirring; At least one compound selected from the group consisting of diethylenetriamine, ethylenediamine, triethylenetetraamine, and melamine solution is added to and reacted with a compound having two or more isocyanate groups in a weight ratio of 100: 20 to 300 to form a urea bond. It is prepared by forming a.

The microcapsules prepared according to the present invention are excellent in thermal stability and firm so that the phase change material therein does not flow out of the capsule. Therefore, it has excellent heat storage and heat dissipation properties, and especially when applied to textile products, the structure of the capsule can be maintained even by processing and repeated washing, and the applicability is excellent because the particle size is sufficiently small.

Description

A preparation method of thermostable microcapsules containing phase change materials and articles including microcapsules prepared thereby}

The present invention relates to a method for producing a microcapsule having excellent thermal stability containing a phase change material and to an article comprising the microcapsules produced by the present invention, and more particularly, to polymerized from a monomer having an alkyl group having 8 to 18 carbon atoms. The present invention relates to a method for preparing microcapsules using a polymer as a phase-change material and an article including the microcapsules prepared accordingly.

Phase change material refers to a material that dissipates heat at the freezing point and absorbs heat at the melting point by using the difference between the freezing point and the melting point. Products with such phase change materials are effective in the utilization and management of energy by heat storage and heat radiation due to the above characteristics.

Therefore, as a method of storing energy, various research results and examples using phase change materials have recently been published. In addition, as part of a method for viewing the maximum effect of the phase change material, a method using microcapsules has been developed. For example, Korean Patent Publication Nos. 2000-14626 and 2000-14627 disclose the preparation of microcapsules by coating phase-change organic compounds such as aliphatic or aromatic compounds with a polymer material and containing them in a latent heat storage material. A flooring material effective for heat storage and a method of manufacturing the same are disclosed, and Korean Patent Publication No. 97-8265 discloses a latent heat storage material in the form of a spherical microcapsule that can be used for heating and keeping warm, and a method for manufacturing the same. In the above patents, as the phase change material, an inorganic hydrate or a paraffinic compound having a melting point of 40 ° C. or more is used, and the prepared microcapsules have a particle diameter of about 1 mm. Moreover, in order to provide durability, it has a double and triple shell structure.

On the other hand, U.S. Patent No. 5,290,904 has a diameter of less than 10 µm and contains paraffinic hydrocarbons selected from the group consisting of n-heptacoic acid, n-hexacoic acid, n-pentacoic acid, n-tetracoic acid, etc. as means for absorbing heat energy. Although a heat shield including a plurality of microcapsules is described, the heat shield prepared according to the above method is poor in durability, water vapor permeability, elasticity, etc., and in particular, an acrylic compound is used as a binder. In this case, there is a problem that durability is lowered.

U. S. Patent No. 5,851, 338 also describes dispersion compositions containing encapsulated phase change materials for penetration into foamed substrates that have already been cured and crosslinked, the dispersion composition comprising paraffinic hydrocarbons dispersed through an acrylic binder. It is described as being applied to thin polyurethane foams, including microspheres containing phase change material, having a thickness of 20 mm to 1000 mm.

Meanwhile, in order to absorb heat generated from the human body or to prevent heat radiation from the human body when exposed to a cold external environment, a method of applying a phase change material to the fiber is known. And coating on the back side of the fabric has been used. U. S. Patent No. 6,077, 597 discloses a first layer having a substrate coated with a polymer binder in which a plurality of microspheres containing a phase change material are dispersed, and a second layer of individual fibers in which a plurality of microspheres containing a phase change material are dispersed. And a thermal barrier fiber system consisting of a third layer of flexible substrate. However, this conventional method has a disadvantage in that the feel of the fiber is not good because a large amount of resin is used to attach the microcapsules to the fiber.

Such a conventional microcapsule is a method in which the core located inside the capsule is leaked out through the pores of the shell to exert an effect, or the capsule is broken by an external pressure to exert the effect. There was a problem that was not suitable for use in large fibers.

In particular, the conventional microcapsules have a problem that the heat storage and heat dissipation effect is reduced because the core flows out of the shell when subjected to a high temperature during processing or use, and the effect of heat storage and heat dissipation is reduced by repeated washing.

Accordingly, an object of the present invention is to provide a method for producing a microcapsules excellent in the durability and heat storage, heat dissipation effect excellent in the heat treatment is excellent enough to apply to a variety of applications, the average particle diameter is small enough.

Another object of the present invention is to provide a method for producing a microcapsule having excellent thermal stability having a core-cell structure using a polymer polymerized from an alkyl group-containing monomer having 8-18 carbon atoms as a phase change material.

Another object of the present invention is to provide an article comprising the prepared microcapsules.

According to one aspect of the invention,

In a solution in which the surfactant is dissolved at 0.2 to 10 parts by weight with respect to 100 parts by weight of water,

10 to 90% by weight of a polymerizable monomer phase change material having 0 to 70% by weight of a non-polar organic solvent, an alkyl group having 8 to 18 carbon atoms, and 10 to 50% by weight of a compound having two or more isocyanate groups, the sum of which is 100% by weight Adding an organic phase of 10 to 50 parts by weight and emulsifying under stirring; And

At least one compound selected from the group consisting of diethylenetriamine, ethylenediamine, triethylenetetraamine, and melamine solution is added to and reacted in a weight ratio of 100: 20 to 300 with respect to the compound having two or more isocyanate groups, thereby providing urea. Forming a bond;

Provided is a method for preparing microcapsules having excellent thermal stability including a phase change material to be included.

According to another aspect of the present invention,

Provided is a heat-radiating fiber product, a polymer resin product, a building material, and the like, including microcapsules having excellent thermal stability including a phase change material prepared by the method of the present invention.

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

As described above, the phase change material is generally a material capable of absorbing or releasing thermal energy due to crystallization of liquid to solid and thermal transition of melting based on a constant temperature. It exists in the state and when it cools below the limit temperature, it functions to release thermal energy to the surroundings, causing a phase transition from the liquid state to the solid state. Therefore, the present invention can be variously applied to applications requiring temperature stability. In particular, since it has a heat storage and heat dissipation effect, when applied to the fiber it is possible to maintain a constant body temperature of the fiber wearer regardless of the temperature change of the external environment or human activity. In addition, it is possible to realize excellent temperature stability by using axial heat radiation effect in various fields such as overheating prevention of electronic products, freezing prevention such as water and sewage.

As such a phase change material, inorganic hydroxides such as plastic crystals such as 2,2-dimethyl-1,3-propanediol, calcium chloride hexa hydride, lithium nitride trihydride, and zinc nitride hexa hydride And paraffinic hydrocarbons selected from the group consisting of n-heptacoic acid, n-hexacoic acid, n-pentacoic acid, n-tetracoic acid and the like have been mainly used.

However, the present inventor solves the problems of the prior art and maximizes the effect of the phase change material, and is also suitable for use in the post-treatment of textile products such as clothing, textiles, non-woven fabrics, knitted fabrics, etc. In addition, to prevent overheating or paint of electronic products Studies have been conducted to provide microcapsules of phase change materials that can be applied to heat-retaining properties and applied to building materials. As a result, certain alkyl group-containing monomers and polymers obtained therefrom act as phase change materials. In addition, it has been found that interfacial polymerization of ethylenediamine and isocyanate of a polyfunctional polyurea-forming monomer in the presence of these monomers can form urea bonds to prepare microcapsules having excellent thermal stability having a core-shell structure.

Furthermore, the microcapsules prepared as described above exhibit repetitive phase change behavior and can be easily processed and applied to various articles including fibers, polymer resins, and building materials.

The microcapsules having excellent thermal stability of the present invention include monomers having an alkyl group having 8 to 18 carbon atoms as a phase change material and polymers thereof.

In the present invention, the alkyl group in the polymerizable monomer having an alkyl group having 8 to 18 carbon atoms serving as a phase change material is selected from the group consisting of normal paraffinic and cyclic paraffinic.

Representative examples of the polymerizable monomer having an alkyl group having 8 to 18 carbon atoms include acrylic esters such as octadecane, hexadecane, tetradecane, dodecane, decane, octane, cyclooctane and phenylcyclohexane, methacrylic esters, and the like. Vinyl esters of homologous organic acids, and the like, which may be used alone or in admixture.

It is preferable to include about 0.05-5 equivalent% of the substance which can act as a polymerization initiator in these monomers. As the polymerization initiator, for example, a general radical polymerization initiator including azobisisobutyronitrile (AIBN), benzoyl peroxide and the like can be used. Depending on the type of monomer, various types of polymerization initiators may be used. However, these polymerization initiators are not necessarily required.

In the present invention, the surfactant is first mixed with water so as to emulsify the phase change material forming the core.

As the surfactant, nonionic surfactants, anionic or cationic surfactants may be used. Examples of the nonionic surfactants include nonylphenoxyl polyethoxyethanol, octylphenoxyl polyethoxyethanol, lauryl polyethoxyethanol, cetyl polyethoxyethanol, stearyl polyethoxyethanol, and oleyl polyethoxyethanol. , Sorbitan stearate, polyethoxyethanol sorbitan stearate, sorbitan oleate, polyethoxyethanol sorbitan oleate, sorbitan mono- laurate, polyethoxyethanol sorbitan mono- laurate and the like; It can be used alone or as a mixture of two or more.

Anionic surfactants or cationic surfactants may be used in place of the nonionic surfactants, and examples thereof include sodium lauryl sulfate or cetyltrimethylammonium chloride. Use of anionic or cationic surfactants reduces the size of the resulting microcapsules.

The concentration of the surfactant can be varied depending on the size of the capsule to be prepared. The smaller the amount of surfactant added, the larger the size of the microcapsules.

The surfactant is added in an amount of 0.2 to 10.0 parts by weight, preferably 0.5 to 5.0 parts by weight, based on 100 parts by weight of water. If the added amount of the surfactant is less than 0.2 parts by weight, there is a problem that the size of the particles is non-uniform, if it exceeds 10.0 parts by weight there is a problem that the microcapsule recovery process becomes difficult.

Next, 10-50 parts by weight of an organic phase which is not mixed with water per 100 parts by weight of water is added to the solution containing the surfactant, and emulsified with sufficient stirring at 300-400 rpm.

The solution in which the organic phase is added to the solution containing the surfactant is hereinafter referred to as emulsion. When the content of the organic phase in the emulsion is less than 10 parts by weight, the particles are not uniformly dispersed. When the content of the organic phase is more than 50 parts by weight, the stability of the emulsion is reduced and microcapsules are hardly produced.

The organic phase may be composed of 0 to 70% by weight of a nonpolar organic solvent, 10 to 90% by weight of a phase change material which is a polymerizable monomer having an alkyl group having 8 to 18 carbon atoms, and 10 to 50% by weight of a compound having two or more isocyanate groups. The nonpolar organic solvent, the phase change material, and the compound having two or more isocyanate groups are blended so that the sum is 100% by weight within the above range.

The organic solvent is present in the organic phase a compound containing a phase change material and two or more isocyanate groups, acts as a solvent or a diluent of the phase change material, and prevents the compound containing two or more isocyanate groups from reacting with water do. As the nonpolar organic solvent, at least one solvent selected from the group consisting of cyclohexane, toluene, pentane, hexane, heptane, octane, ethyl acetate, methylene chloride, chloroform, carbon tetrachloride, and the like may be used.

Preferably cyclohexane or toluene is used. If the content of the organic solvent exceeds 70% by weight, there is a problem that the production of empty microcapsules is increased.

The organic solvent may not be used, but when the organic solvent is not used, there is a problem in that side reactions of the isocyanate groups are increased, and the temperature during emulsification should be raised to the extent that the phase change material can be sufficiently liquefied.

The paraffinic compound, which is a polymerizable monomer having an alkyl group having 8 to 18 carbon atoms serving as the phase change material, is contained in an organic phase of 10 to 90% by weight. When the content of the paraffinic compound as a phase change material is less than 10% by weight, there is a problem that the probability of emptying the microcapsules is also increased, and when the content of the paraffinic compound exceeds 90% by weight, the unencapsulated paraffinic compound is increased.

The compound containing two or more isocyanate groups is a group consisting of toluene-2,4-diisocyanate, methylene diphenyl isocyanate, hexyl diisocyanate, hydrogenated biphenylmethane diisocyanate, isophorone diisocyanate, triisocyanate and polyisocyanate It is selected from, and they can be used alone or in mixture of two or more. Preferably toluene-2,4-diisocyanate is used.

When the content of the compound having two or more diisocyanate groups is less than 10% by weight, there is a problem in that the capsule wall is collapsed due to thin capsules, and when the content exceeds 50% by weight, the content of unreacted diisocyanate is increased.

As the water-soluble shell monomer which adds an organic phase to the water containing the surfactant and stirs to emulsify the phase-change substance which forms a core, and forms a shell by urethane bond with an isocyanate group, it is diethylene. One or more mixtures selected from the group consisting of triamine, ethylenediamine, triethylenetetraamine, melamine solution, and the like are added. Diethylenetriamine is the most preferred water soluble shell monomer.

The water soluble shell monomer reacts with a compound containing at least two diisocyanate groups in the organic phase to form urea bonds. That is, a shell having a urea bond is formed on the microparticle core of the phase change material, that is, a microcapsule having a core-shell shape is formed.

The water-soluble shell monomer is added so that the weight ratio of the compound having two or more diisocyanate groups: water-soluble shell monomer is 100: 20 to 300. If the content of the water-soluble shell monomer is less than 20 parts by weight, there is a problem in the mechanical durability of the resulting microcapsules, if more than 300 parts by weight there is a problem that the unreacted amine is increased.

As an example of a method of adding and reacting a water-soluble shell monomer to the emulsion, one water-soluble shell monomer compound selected from the group consisting of diethylenetriamine, ethylenediamine, triethylenetetraamine, and melamine solution is used in the total amount thereof. The amount corresponding to 1/3 is first diluted 5-10 times in water and slowly added to the emulsion, and then the remaining water-soluble shell monomer is added all at once, and the urea bond is formed by constant stirring at 300 to 400 rpm to form a shell. . This reaction is carried out in a temperature range of generally known urea bonds, for example at room temperature (about 25 ° C) to 40 ° C.

As such, by forming the urea bond forming the shell, microcapsules having a core / shell structure are formed.

Thereafter, optionally further, the monomers constituting the core in the microcapsules having a core / shell structure are further polymerized to raise the temperature to 60 to 100 ° C and polymerize for 90 to 100 minutes to further increase the heat resistance of the microcapsules. Prepare capsules.

This allows the chemical reaction in the reactor to proceed very uniformly, not only to increase the encapsulation efficiency but also to promote the diffusion of the reactants, thereby increasing the reaction efficiency and thus forming a rigid shell.

The microcapsules having a core-shell structure are prepared by the method of the present invention, and in the microcapsules of the core-shell structure, the phase change material forms a core and the urea binding component forms a shell. The filling rate of the phase change material in the prepared microcapsules is about 50 to 90%, and the average particle diameter is about 0.4 to 20㎛.

Microcapsules containing the phase change material prepared by the present invention, for example, can be applied to the fibers by mixing and spinning in the spinning step during the manufacturing of the fiber, as well as heat storage and heat-dissipating fibers through the application, etc. in the post-processing step of the fiber It can be used to manufacture products. The textile products include clothing, textiles, nonwovens, and knitted fabrics.

In addition, the microcapsules containing the phase change material, in addition to the textile products, polymer resin products used in the manufacture of overheat prevention parts installed to prevent overheating of electronic products such as computers, mobile phones, automobiles, etc. It can be added when manufacturing sewer construction materials, natural or synthetic rubber, or paints to improve the temperature stability of the final product.

As such, the robust and fine microcapsules prepared according to the present invention are easy to apply to articles, and the articles having the microcapsules prepared according to the present invention not only maintain excellent heat storage and heat dissipation even after processing, In this case, it has a strong durability even after repeated washing.

For example, if the textile product is made using this, the comfort of the textile wearer is enhanced.

Hereinafter, the present invention will be described in more detail with reference to Examples. The following examples illustrate the invention but do not limit the invention.

Example 1

2.5 g of nonylphenoxyl polyethoxyethanol (trade name: NP-10) was dissolved in 97.5 g of distilled water, and then 7.0 g of cyclohexane, 9.0 g of stearyl methacrylate containing 1% of AIBN, and toluene-2,4 3.0 g of diisocyanate was added and stirred at 300 rpm. Then, 1.0 g of diethylenetriamine was diluted in 10 g of distilled water and slowly added at a rate of 2.0 g per minute, and then 2.5 g of diethylenetriamine was added all at once.

The stirrer was kept constant at 300 rpm at room temperature to form a urea bond, after which the temperature of the reactor was raised to 70 ° C. and then reacted for 90 minutes to prepare microcapsules. The average particle diameter of the prepared microcapsules was 0.9 μm. As measured by thermogravimetric analysis, it was observed that there was no weight change up to 290 ° C. when heating at 10 ° C./min.

Comparative Example 1

Microcapsules were prepared using the same content as in Example 1 but using octadecane instead of AIBN 1% containing stearyl methacrylate. The average particle diameter of the prepared microcapsules was 0.9 μm. As a result of measuring by thermogravimetric analysis, it was observed that the weight was reduced from 150 ° C. when heated to 10 ° C./min.

Example 2

The same procedure as in Example 1 was carried out except that the addition amount of the toluene-2,4-diisocyanate and diethylenetriamine was 1: 1.5. The average particle diameter of the prepared microcapsules was 0.9 μm.

Example 3

The same procedure as in Example 1 was carried out except that 0.4% by weight solution of polyethoxyethanol sorbitan monolorate (trade name Tween 80) was used instead of nonylphenoxyl polyethoxyethanol. The average particle diameter of the prepared microcapsules was 20 μm.

Example 4

1.0 g of the microcapsules prepared according to Example 1 were uniformly mixed with a polyurethane coating solution consisting of 0.5 g of polyurethane prepolymer having a number average molecular weight of about 2000 and 3.5 g of methyl ethyl ketone, and then the size of about 100 It was applied to a cotton fabric having a weight of 1.0 g 2 cm 2 and subjected to a dry heat treatment step at 110 ℃. The washing test was performed 10 times by KSK 0810 method and the microscopic observation of the fabric confirmed that the microcapsules of the same degree as before the washing were attached to the fabric. Therefore, it was found that washing durability is excellent.

The endothermic amount of the fabric was measured using a differential scanning calorimeter (Perkin-Elmer DSC-7). An endotherm was observed at 25-35 ° C., 10.5 cal per gram of fabric, and 10.2 cal after 10 washes. The calorific value was the same as the endothermic amount and was observed at 20 to 30 ° C.

Example 5

The microcapsules prepared according to Example 1 were mixed to prepare a polymer resin product for a computer overheat prevention part to prepare a product. As a result of observing the final product containing the microcapsules of the present invention, overheating was reduced compared to the existing product.

Example 6

The microcapsules prepared according to Example 1 were added to product raw materials in the manufacture of shoes to complete the product, and as a result of using the final product, it felt twice as cold as ordinary shoes without the microcapsules according to the present invention. It was confirmed that.

The product manufactured according to the present invention has excellent thermal stability of the microcapsules so that the phase change material therein does not flow out of the capsule and has excellent heat storage and heat dissipation.

In addition, it is possible to maintain the structure of the capsule by the processing for applying to the article, it is advantageously applicable to various applications because the particle size is small enough.

Claims (16)

In a solution in which the surfactant is dissolved at 0.2 to 10 parts by weight with respect to 100 parts by weight of water, 10 to 90% by weight of a polymerizable monomer phase change material having 0 to 70% by weight of a nonpolar organic solvent, an alkyl group having 8 to 18 carbon atoms, and 10 to 50% by weight of a compound having two or more isocyanate groups, the sum of which is 100 Adding 10 to 50 parts by weight of an organic phase, which is mixed to a weight%, and emulsifying under stirring; And At least one compound selected from the group consisting of diethylenetriamine, ethylenediamine, triethylenetetraamine, and melamine solution is added to and reacted with a compound having two or more isocyanate groups in a weight ratio of 100: 20 to 300 to form a urea bond. Forming a; Microcapsule manufacturing method containing a phase change material, characterized in that it comprises a. The method of claim 1, wherein a part or all of the phase change material forming the core of the microcapsules is in a polymerized state. According to claim 1, The phase change material is an acrylic ester, methacryl having one alkyl group selected from the group consisting of octadecane, hexadecane, tetradecane, dodecane, decane, octane, cyclooctane and phenylcyclohexane Microcapsules containing a phase change material, characterized in that selected from esters and vinyl ester compounds of cognate organic acids having the same carbon number as the alkyl group The method of claim 1, wherein the surfactant is nonylphenoxyl polyethoxyethanol, octylphenoxyl polyethoxyethanol, lauryl polyethoxyethanol, cetyl polyethoxyethanol, stearyl polyethoxyethanol, oleyl polyethoxy Nonionics including ethanol, sorbitan stearate, polyethoxyethanol sorbitan stearate, sorbitan oleate, polyethoxyethanol sorbitan oleate, sorbitan mono- laurate, polyethoxyethanol sorbitan mono- laurate Microcapsules containing a phase change material, characterized in that selected from the type of surfactant. The compound of claim 1, wherein the compound containing two or more isocyanate groups is selected from toluene-2,4-diisocyanate, methylene diphenylisocyanate, hexyl diisocyanate, hydrogenated biphenylmethane diisocyanate, isophorone diisocyanate, triisocyanate and A method for producing a microcapsule containing a phase change material, characterized in that it is a single or a mixture of two or more selected from the group consisting of polyisocyanates. The phase change according to claim 1, wherein the nonpolar organic solvent is a single or mixture of two or more selected from the group consisting of cyclohexane, toluene, pentane, hexane, heptane, octane, ethyl acetate, methylene chloride, chloroform and carbon tetrachloride. Microcapsules containing this substance. The method of claim 1, wherein the microcapsules have a core-shell structure, and wherein the phase change material forms a core and the urea binding component forms a shell. The method of claim 1, wherein the microcapsules have a particle diameter of 0.4 to 20 μm. 9. The method of claim 1, further comprising, after forming the urea bond, subsequently polymerizing at 60 to 100 ° C. 10. A heat storage and heat dissipating textile product, characterized in that the microcapsules prepared by the method of any one of claims 1 to 8 are applied. A heat storage and heat dissipating fiber product, characterized in that the microcapsules prepared by the method of claim 9 are applied. 11. The heat storage and heat dissipating textile product according to claim 10, wherein the textile product is clothing, woven fabric, nonwoven fabric and knitted fabric. Claims 1 to 8, wherein the microcapsules prepared by the method of any one of the electronic products, characterized in that the application of the polymer resin product for thermal protection of heat or paint for automotive overheating. A polymer resin product for preventing heat dissipation of heat and paint of electronic products and automobiles, characterized in that the microcapsules manufactured by the method of claim 9 are applied. A heat-radiating building material, characterized in that the microcapsules produced by the method of any one of claims 1 to 8 are applied. A heat-radiating building material, characterized in that the microcapsules prepared by the method of claim 9 are applied.