JP2006263681A - Microcapsule granulated product and method of using the same - Google Patents

Abstract

To obtain a microcapsule granulated product having a high packing density per unit volume, high strength against bending and shearing, and excellent fluidity.
An average particle diameter of a microcapsule granulated product is set to 100 μm to 30 mm, and a roundness (short diameter / long diameter) is set to a range of 0.2 to 1. The compound in the microcapsule is preferably a heat storage material, and more preferably used as a heat storage material for air conditioning, a bedding material, or a building material.
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Description

  The present invention relates to a microcapsule containing a compound, in particular, a microcapsule granule in which a microcapsule containing a heat storage material is fixed or supported, and a method of using the same.

  As a method for effectively storing heat energy, various heat storage materials, in particular, a method using a latent heat storage material accompanying a phase change of a substance has been mainly used for air conditioning. Compared to the method using only sensible heat without phase change, this method can store a large amount of thermal energy in a narrow temperature range including the melting point, thus not only reducing the capacity of the heat storage material, Since a large temperature difference does not occur for a large amount of heat storage, the heat loss can be suppressed to a small amount.

  Since latent heat storage materials are difficult to handle with solid and liquid phase changes during melting and solidification, a method of microencapsulating the heat storage materials has been proposed to apparently suppress phase changes. A microcapsule is always in a liquid state when dispersed in a medium such as water and can transfer latent heat in a fluid state, and therefore has been proposed as a heat medium for air conditioning (for example, Patent Document 1). reference). On the other hand, by removing the dispersion medium by a method such as drying or filtration, it can always be used as a solid heat storage material, and it can be used for underfloor air conditioning, heating equipment, etc. Proposals have been made (see, for example, Patent Documents 2 to 5).

  A plurality of microcapsules can be bound and processed into a granulated product having a size of several μm to several cm. Unlike the case of powder, the granulated product is difficult to scatter, and since a void passage is obtained between particles, heat can be exchanged between gas and solid by flowing air between them, which is an industrially preferable form. . For example, in the extrusion granulation method, after adding moderate moisture to the microcapsule powder, pressure is applied, and pressure is applied through a hole having a desired diameter to extrude a rod-like or granular granulated product. . The size of the granulated product can be adjusted by cutting the extruded die diameter and the extruded bar-shaped granulated product into an appropriate length (see, for example, Patent Documents 2 to 4).

However, it has been found that various problems arise when the shape of the granulated product obtained by the above method is very long, that is, the ratio of the major axis to the minor axis is too large. For example, when it is used as a solid heat storage material for air conditioning, if it is too long, the bulk density will be small when filled in a container under the floor or a fixed volume, the amount that can be accommodated and retained will be small, and the amount of heat storage will be insufficient. There was a thing. In addition, when kneaded into the building material board, the heat storage material may protrude from the board, or the strength of the board may decrease. Furthermore, when applied to bedding applications such as pillows, if the length is too long, it may break or bend during use. Furthermore, since the slipperiness between the granulated materials is poor, there is a sense of incongruity as a tactile sensation, and when the granulated material is moved by a conveyor as a problem in the manufacturing process, the fluidity as the granulated material is poor. Often, the granulated material is clogged, for example, when it is stagnant or transported in a cylindrical pipe.
JP-A-5-163486 JP 2001-81447 A JP 2001-303031 A JP 2001-303032 A JP 2001-58126 A

  An object of the present invention is to obtain a microcapsule granulated product having a high packing density per unit volume, high strength against bending and shearing, and excellent fluidity.

  In the microcapsule granulated product whose main component is a microcapsule encapsulating the compound, the average particle size of the microcapsule granulated product is 100 μm to 30 mm, and the roundness (minor axis / major axis) is 0. It has been found that the problem can be solved by setting in the range of 2-1.

  The microcapsule granulated product shown in the present invention is obtained by fixing a plurality of microcapsules, and the ratio between the maximum length and the shortest length (roundness) of the granulated product is set within a certain range. As a result, first of all, it is possible to efficiently fill a large volume of granulated material in a certain volume, especially when the compound is a heat storage material, etc. A maximum heat storage density can be obtained by using it in a regenerative air conditioning system. Secondly, it is difficult to break against physical external pressure, especially when it is filled in bedding, etc., and it can be used as a very stable building material when kneaded into cement, plaster, resin, etc. The fluidity of the granulated product is increased, and the effects such as the transportability and the feel of the filling material in the bag are preferable.

  Examples of the compound encapsulated in the microcapsule used in the present invention include fragrances, dyes, pharmaceuticals, foods, and adhesives, but it is most preferable to use a heat storage material. In particular, the latent heat storage material is used for the purpose of storing heat using latent heat accompanying phase transition, and any compound having a melting point or a freezing point can be used. Specific heat storage materials include aliphatic hydrocarbon compounds (paraffin compounds) such as tetradecane, hexadecane, octadecane, and paraffin wax, inorganic eutectics and inorganic hydrates, and fatty acids such as palmitic acid and myristic acid. , Aromatic hydrocarbon compounds such as benzene and p-xylene, ester compounds such as isopropyl palmitate and butyl stearate, and compounds such as alcohols such as stearyl alcohol, preferably having a heat of fusion of about 80 kJ / kg or more. Compounds that are chemically and physically stable and inexpensive are used. These may be used as a mixture, and a supercooling preventing material, a specific gravity adjusting material, a deterioration preventing agent and the like may be added as necessary. It is also possible to use a mixture of two or more microcapsules having different melting points.

  As a method for producing the microcapsules of the present invention, a physical method and a chemical method are known. In particular, as a method for microencapsulating a latent heat storage material, an encapsulation method by a composite emulsion method (Japanese Patent Laid-Open No. Sho 62-1452). Gazette), a method of spraying a thermoplastic resin on the surface of the heat storage material particles (Japanese Patent Laid-Open No. 62-45680), and a method of forming a thermoplastic resin in the liquid on the surface of the heat storage material particles (Japanese Patent Laid-Open No. 62-149334). Publication), a method of polymerizing and coating a monomer on the surface of heat storage material particles (Japanese Patent Laid-Open No. 62-225241), a method for producing a polyamide-coated microcapsule by interfacial polycondensation reaction (Japanese Patent Laid-Open No. 2-258052), and the like. Method is used.

  As the membrane material of the microcapsule, polystyrene, polyacrylonitrile, poly (meth) acrylate, polyamide, polyacrylamide, ethylcellulose, polyurethane, which are obtained by a method such as an interfacial polymerization method, an in-situ method, a radical polymerization method, Aminoplast resin, or synthetic or natural resin using gelatin and carboxymethylcellulose or gum arabic coacervation method is used, melamine formalin resin, urea formalin resin, polyamide, polyurea, polyurethaneurea are preferred, and physical It is particularly preferable to use a microcapsule using a melamine formalin resin film or a urea formalin resin film by an in situ method that is chemically and chemically stable.

  The volume average particle diameter of the microcapsule single particle according to the present invention is preferably in the range of 0.1 to 20 μm, and more preferably in the range of 1 to 10 μm. When the particle diameter is larger than 20 μm, the mechanical shearing force tends to be extremely weak, and when the particle diameter is smaller than 0.1 μm, the fracture is suppressed, but the film thickness becomes thin and the heat resistance tends to be poor. The volume average particle diameter described in the present invention represents the average particle diameter of the microcapsule particles in terms of volume, and in principle, particles having a fixed volume are sieved in order from the smallest, and the particles corresponding to 50% of the volume. Means the particle size at the time of separation. The volume average particle size can be calculated by actual measurement by microscopic observation, but it can be automatically measured by using a commercially available electrical or optical particle size measuring device. Measurement was performed using a particle size measuring device Multisizer type II manufactured by Coulter.

  The microcapsule granulated product of the present invention is particles in a form in which microcapsules are fixed alone or together with a binder or the like. As a method of obtaining the granulated product of the present invention, there is a method of obtaining a powder or granulated product in a single step by using a microcapsule dispersion using various drying devices such as a spray dryer, drum dryer, freeze dryer and the like. However, only this drying process can obtain a powder having a low bulk density of several tens of μm at most, and it has been difficult to finish a granulated product with a high bulk density of several millimeters to several centimeters in diameter.

  In contrast to the above method, there is known a method in which a microcapsule dispersion liquid is made fluid and processed into a clay shape to apply a pressure to granulate it into a desired shape and size. In the pressure granulation method, the microcapsule particles are close to a closely packed structure and the bulk density is increased, resulting in an increase in particle strength. As a method of processing the microcapsule dispersion into a clay, a water-absorbing pigment is added until the dispersion becomes a clay, or after the microcapsule dispersion is made into a powder, a binder and appropriate moisture are added. A method is mentioned. As specific examples of the pressure-type granulation method, an extrusion-type granulation method, a rolling granulation method, a compression molding machine, and the like are preferable methods. In addition, as a method of increasing the roundness rate, there is a method of sizing while rotating at high speed on a rotating square mesh and gradually grading the angle. To increase the roundness rate, the rotational speed can be increased. In addition, the roundness is closer to 1 by adjusting the size for a long time.

  Further, as a method for obtaining a microcapsule granulated product having a high roundness, there is a method in which microcapsules are attached to solid particles that are close to a perfect spherical shape as a core material. As solid particles, for example, porous silica, calcium carbonate, calcium silicate, organic polymer particles, and fibrous particles can be used as base particles, and a microcapsule dispersion or a microcapsule powder can be used around these solid particles. By adhering while flowing, a granulated product similar to the solid particles is obtained. The larger the microcapsule mass ratio with respect to the solid particles, the better. The mass ratio of the solid particles is preferably 50% or less, preferably 30% or less of the amount of the finished microcapsule granulated substance.

  The microcapsule granulated product of the present invention is preferably a microcapsule containing a heat storage material, and is particularly preferable because it is most effective when used as a heat storage material for air conditioning, bedding material, or building material. In these applications, the average particle diameter of the microcapsule granulated product is 100 μm to 30 mm, preferably 500 μm to 10 mm, and the roundness (short diameter / major diameter) is 0.2 to 1, more preferably 0.5 to. In the range of 1, the closer to 1, that is, the closer to the true sphere, the higher the packing density per unit volume, the higher the bending strength, and the better the fluidity. A granulated product having an average particle size of less than 100 μm is almost powdery and may be harsh in handling. If it exceeds 30 mm, it may be too large to be used as a bedding or building material. is there. In addition, the object of the present invention may not be achieved below the roundness. The short diameter, the long diameter, and the average particle diameter described in the present invention indicate the shortest diameter, the longest diameter, and the average value obtained by measuring at least 10 granulated particles with an industrial caliper or an optical microscope having a measuring function. .

  The binder used in the microcapsule granulated product of the present invention is a component that has the effect of increasing the cohesive strength, water resistance and strength between the microcapsules, and the microcapsule is in a dispersion state or a powder state before the granulation step Added to the inside. Specific examples of the binder used in the present invention include conventionally known natural polymers having a binding ability and film-forming ability, natural polymer modified products (semi-synthetic products), synthetic polymers and inorganic compounds. be able to.

  Examples of natural polymer substances include polysaccharides such as oxidized starch and phosphated starch, and proteins such as gelatin, casein, glue and collagen. Semi-synthetic products include propylene glycol alginate, viscose, methylcellulose, ethylcellulose, methylethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxypropylethylcellulose, carboxymethylhydroxyethylcellulose, and hydroxypropylmethylcellulose. Fibrin derivatives such as phthalate are used.

  Synthetic polymers include polyvinyl alcohol, partially acetalized polyvinyl alcohol, allyl-modified polyvinyl alcohol, modified polyvinyl alcohols such as polyvinyl methyl ether, polyvinyl ethyl ether, and polyvinyl isobutyl ether, poly (meth) acrylic acid esters, poly ( Hydrophilic polymers of meth) acrylic acid ester partial saponified products, poly (meth) acrylic acid derivatives such as poly (meth) acrylic amide, polyethylene glycol, polyethylene oxide, polyvinyl pyrrolidone, and vinyl pyrrolidone vinyl acetate copolymers, Polyvinyl acetate, polyurethane, styrene butadiene copolymer, carboxy-modified styrene butadiene copolymer, acrylonitrile butadiene copolymer, methyl acrylate acrylate copolymer Body, and latexes such as ethylene-vinyl acetate copolymer, melamine-formaldehyde precondensate, a urea-formalin precondensate, thermoplastic elastomers, and the like.

  The binder is used in the range of 1 to 80% (m / m), preferably 3 to 50% (m / m) with respect to the mass of the microcapsule solid content. If it exceeds 80% (m / m), the heat storage performance may be lowered, and if it is less than 1% (m / m), the binding ability may be lowered.

  The microcapsule granulated product according to the present invention can be used alone, but is dispersed and mixed with fibers, resin, cement, gypsum, etc., compounded with a gas adsorbent or a heating material, or filled in a packaging material. It is possible to use it. Further, it can be used in combination with a fragrance, a preservative, a colorant, a deterioration inhibitor, a gas adsorbent, a heating material, and the like.

  Hereinafter, the present invention will be described in more detail by way of examples. However, the present invention is not limited to these examples. In addition, the percentage in an Example is a mass reference | standard. The bulk density described in the examples and comparative examples indicates the bulk density in a state where forced filling such as vibration of the granulated product and taps is not performed.

  Preparation of microcapsule dispersion: 60 g of normal octadecane having a melting point of 28 ° C. and normal nonadecane as a latent heat storage material in 100 g of a sodium salt aqueous solution of 5% styrene-maleic anhydride copolymer adjusted to pH 4.5. 20 g of the mixture (melting point about 30 ° C.) was added with vigorous stirring and emulsification was performed. Next, 6 g of melamine, 9 g of 37% formaldehyde aqueous solution and 15 g of water were mixed, adjusted to pH 8, and a melamine-formalin initial condensate aqueous solution was prepared at about 80 ° C. The total amount was added to the above emulsion and heated and stirred at 70 ° C. for 2 hours to carry out an encapsulation reaction. Then, the pH of this dispersion was adjusted to 9 to complete the encapsulation, and the heat storage material microcapsule dispersion Got. The volume average particle size of the obtained microcapsules was 2.5 μm.

When this microcapsule dispersion was spray-dried with a spray dryer, a powder having a volume average particle size of 50 μm was obtained. To 100 g of this powder, 50 g of a commercial acrylic latex having a solid content concentration of 40% was added in a dispersion and mixed well, and then a granulated product having a minor axis of 3 mm and a major axis of 20 mm was obtained using an extrusion granulator. . Further, the granulated product was cut using a granulator, and wet particles having a minor axis of 3 mm and a major axis of 6 mm were obtained. By drying the wet particles at 100 ° C. for 30 minutes, a microcapsule granulated product having a particle size of 4.5 mm, a roundness of 0.50 and high strength and high fluidity was obtained. The bulk density of the granulated product was 0.53 g / cm ³ .

  After 100 g of Portland cement and 30 g of water were mixed well for 2 minutes, 30 g of the granulated product obtained in Example 1 was added and kneaded for 2 minutes to obtain a mortar slurry. The obtained mortar slurry was subjected to dehydration press molding using a mold and cured at 30 ° C. for 12 hours to obtain a plate-like molded body. The obtained plate-shaped molded article had sufficient strength as a building material. In addition, it was confirmed that an indoor environment that hardly rises above 30 ° C. in summer can be obtained by using the building material having heat storage properties as an interior material for a house.

  As a latent heat storage material, a product obtained by dissolving 15 g of dicyclohexylmethane 4,4-diisocyanate (aliphatic isocyanate manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name Desmodur W) as polyvalent isocyanate in 80 g of dodecyl decanoate having a melting point of 23 ° C. This was added to 100 g of an aqueous solution of 5% polyvinyl alcohol (trade name POVAL 117, manufactured by Kuraray Co., Ltd.), and stirred and emulsified at room temperature until the average particle size became 3 μm. Next, after adding 60 g of 3% polyether aqueous solution (polyether manufactured by Asahi Denka Kogyo Co., Ltd., trade name Adeka Polyether EDP-450) to this emulsion, heating and stirring were performed at 60 ° C. A heat storage material microcapsule dispersion having low viscosity and good dispersion stability was obtained. The volume average particle size of the obtained microcapsules was 3.2 μm.

To 100 g of this microcapsule dispersion, 20 parts of a commercially available acrylic latex having a solid content of 40% and 20 g of fine silica particles as a water-absorbing material were mixed and mixed well with a kneader to form a clay, and then short using an extrusion granulator. A wet granulated product having a diameter of 200 μm and a major axis of 5 mm was obtained. This granulated product was adjusted to have a short diameter of 200 μm and a long diameter of 500 μm using a granulator, and was thermally dried in the same manner as in Example 1. A microcapsule granulated product of 42 g / cm ³ was obtained. To 200 g of this granulated product and 800 g of β hemihydrate gypsum, 500 parts of water and 13 g of a water reducing agent were added, stirred with a mixer and poured into a mold to obtain a gypsum board having a heat storage performance of 10 mm in thickness.

  The gypsum board obtained here was affixed to four walls of 6 tatami mats in a test wooden house, and the room temperature was measured by giving a thermal history between 15 ° C and 30 ° C with a period of 3 hours. The room temperature did not rise above 23 ° C, and it was not felt hot even in the bodily sensation. On the other hand, when a thermal history was given under the same conditions using only a gypsum board without a heat storage sheet, the room temperature was a very unpleasant environment showing a temperature change behavior that was almost the same as the outside temperature.

A microcapsule powder was obtained by the same production method as in Example 1 except that heptadecane having a melting point of 22 ° C. was used as the heat storage material. While rolling 100 g of spherical particles made of porous calcium silicate having a particle size of 10 mm on a rotating disk, while gradually dropping 100 g of this microcapsule powder and 20 g of acrylic latex with a solid content concentration of 40%, around the spherical particles A strong microcapsule granulated product having a particle diameter of 20 mm, a roundness of 0.90, and a bulk density of 0.52 g / cm ³ was obtained. This granulated material is spread under the floor in a residential room at a rate of about 4 kg / m ² and applied to an underfloor regenerative air conditioning system that passes cold air between the particles at night to store cold energy. It was possible to cover most of the cooling capacity in the space under the floor.

A microcapsule dispersion was obtained in the same manner except that instead of n-hexadecane of Example 1, fragrance extracted from wood and hiba oil which is a repellent component were used. This Hiba oil encapsulated microcapsule dispersion was used to obtain a powder having a particle size of 50 μm using a spray dryer. After adding 30 g of a vinyl acetate copolymer latex having a solid content concentration of 50% to 100 g of this powder with water, a rod-like wet having a minor axis of 1 mm and a major axis of 5 mm using the same extrusion granulator as in Example 2. A granulated product was obtained and dried at 100 ° C. for 30 minutes. The dried granulated product was prepared into a hiba oil microcapsule granulated product having a major axis of 2.5 mm, a roundness of 0.40, and a bulk density of 0.56 g / cm ³ using a dry mill.

100 g of this granulated product and 400 g of pulverized wood were mixed well and 20 g of thermosetting resin was mixed, followed by pressure molding at 150 ° C. for 20 minutes to obtain a particle board in which hibera oil-encapsulated microcapsules were kneaded. The destruction of the microcapsules contained in Hiba oil in the board was not observed. The bulk density of this granulated product was 0.42 g / cm ³ . The board filled with this Hiba oil-encapsulated microcapsule granule had aroma and insect repellent effect for a long time.

(Comparative Example 1)
After thoroughly mixing 100 g of the microcapsule powder used in Example 3 and 20 g of the same acrylic latex, using a compression molding machine briquette machine, the particle diameter was 50 mm, the roundness was 0.90, and the bulk density was 0.30 g / cm ^3. A microcapsule granulated product was obtained. Although this granule was tried to be used as a pillow for bedding, it was uncomfortable and could not be used as a pillow. Moreover, although utilization was tried as the heat storage material for building materials similar to Example 1 and Example 3, and the heat storage material for an air conditioning, the packing density was small or it could not be kneaded in a board.

(Comparative Example 2)
When the microcapsule dispersion obtained in Example 1 was dried with a drum dryer, a powder having a particle diameter of 80 μm, a roundness of 0.18, and a bulk density of 0.12 g / cm ³ was obtained. This granulated product not only has a small particle size and a lot of powder, but is very bulky and therefore has a low filling efficiency, and is difficult to use for any of heat storage materials for air conditioning, bedding, and building materials.

(Comparative Example 3)
The granulated product in a wet state having a minor axis of 3 mm and a major axis of 20 mm obtained in Example 1 was dried to have a particle diameter of 11.5 mm, a roundness of 0.15, and a bulk density of 0.18 g / A microcapsule granulated product of cm ³ was obtained. Since this granulated material is very easy to break and bulky, it is difficult to use it for any of heat storage materials for air conditioning, bedding, and building materials.

  In addition to granule granulated products according to the present invention, building materials such as ceilings, walls, and floors, bedding such as pillows and bed pads, and building heat storage for buildings, floor heating, overheating prevention, adsorption heat suppression, hot water storage It can be applied to various fields of use such as applications, air conditioning, civil engineering materials such as roads and bridges, industrial and agricultural thermal insulation materials, clothing materials, household goods, health supplies, and medical materials.

Claims (5)

  In the microcapsule granulated product mainly composed of the microcapsules encapsulating the compound, the average particle size of the microcapsule granulated product is in the range of 100 μm to 30 mm, and the roundness (minor axis / major axis) is in the range of 0.2 to 1. A microcapsule granulated product.   The microcapsule granulated product according to claim 1, wherein the compound is a heat storage material.   A heat storage material for air conditioning comprising the microcapsule granulated product according to claim 2.   A bedding material comprising the microcapsule granulated product according to claim 2.   A building material comprising the microcapsule granulated product according to claim 2.