JPH01236292A - Capsulated heat storage pellet and preparation thereof - Google Patents

Abstract

PURPOSE:To provide capsulated heat storage pellets improved in mechanical strengths and having a heat storage material prevented from oozing out, by forming resin layers preventive of oozing out of the heat storage material on the surfaces of specific heat storage pellets. CONSTITUTION:Pellets of a polyolefin resin (a) (e.g., PE) crosslinked to a degree of 1-90wt.% (hereinafter merely '%') in terms of the gel content by extraction with xylene is immersed in a molten heat storage material (b) heated to a temp. of at least the m.p. of the crystals of the component (a) to prepare heat storage pellets (A) of 0.5-20mm in maximum size comprising the component (a) impregnated with 40-85% component (b). If necessary, the component (b) adhering to the surfaces of the component A is removed. The surfaces of the component A are then covered with a fine powder insoluble in the component (b). The resulting powder-covered pellets are put into an independently suspended state and spray-coated with a coating liquid (B) contg. a resin preventive of oozing out of the component (b) at a temp. of at most the b.p. of the solvent of the coating liquid to form resin layers 0.5-300mum thick and preventive of oozing out of the component (b) on the surfaces of the component A.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to an encapsulated heat storage pellet and a method for manufacturing the same.

[Conventional technology]

Latent Qfj thermal materials, which have the characteristics of a substantially constant heat dissipation temperature and a large M heat density, are being actively developed for application in fields such as building materials and greenhouse horticulture. This latent heat storage material can be used in the following ways: ■ Use it in bulk as an FJQ tank; ■ Enclose the heat storage material in a small container; ■ Encapsulate or microcapsule (hereinafter referred to as "(micro)encapsulation"). Three forms have been proposed: From the point of view of heat exchange efficiency, form (2) is preferable to forms (2) and (2), which have a small surface area per volume.

By the way, heat storage materials made of crystalline long-chain alkyl hydrocarbons, higher fatty acids, higher fatty acid esters, and crystalline organic compounds such as higher aliphatic alcohols do not undergo phase separation as seen in inorganic hydrated salt-based heat storage materials. This is preferable since there are no problems such as overcooling or overcooling. As a (micro)capsule of such an M thermal material, a heat storage pellet made by impregnating a crosslinked polyolefin resin pellet with this fjQ material has been proposed (Japanese Patent Application Laid-Open No. 187782/1982).

These heat storage pellets can be manufactured more economically than the conventional encapsulation method, ie, the orifice method. Furthermore, even when the heat storage material impregnated in the obtained heat storage pellets is melted, the cross-linked polyolefin resin that is the carrier maintains the mechanically strong pellet shape, and the heat storage material is not as strong as when there is no pellet. It is excellent in that there is no problem of leakage.

[Problem to be solved by the invention]

However, the heat storage pellets described in the above-mentioned publication are simply impregnated crosslinked polyolefin resin pellets with a heat storage material and support the heat storage material in the resin, so when the melting-solidification cycle is repeated, the heat storage material is It turned out that there was a problem with it seeping out from inside.

In particular, when the amount of impregnation of the heat storage material is high, for example, when the amount of impregnation is 70% or more, the seepage is significant. In heat storage pellets, the higher the content of heat storage material, the greater the amount of heat storage and the better the efficiency.Therefore, it is desired to develop a method to prevent such seepage of heat storage material and a heat storage pellet without seepage of heat storage material. ing.

In view of the above, the first object of the present invention is to provide an encapsulated heat storage pellet that has excellent mechanical strength and does not allow heat storage material to seep out.

Furthermore, a second object of the present invention is to provide a method for manufacturing encapsulated heat storage pellets that have excellent mechanical strength and do not allow heat storage material to seep out.

[Means to solve the problem]

In order to solve the above first problem, the encapsulated N-thermal pellet of the invention according to claim 1 has a stain of the M-thermal material on the surface of the heat storage pellet formed by impregnating a crosslinked polyolefin resin pellet with a heat storage material. A release-preventing resin layer is formed.

In order to solve the above second problem, the method for producing encapsulated heat storage pellets according to each of the inventions of claims 2 to 5 includes independently floating heat storage pellets formed by impregnating crosslinked polyolefin resin pellets with a heat storage material. Spray coating the heat storage pellets with a seepage-preventing resin coating solution,
A seepage prevention resin layer is formed on the surface of the N heat paste L/7.

In addition to the above, the manufacturing method according to the invention of claim 3 further comprises:
The heat storage pellets are coated with the resin to prevent staining and bleeding at a temperature lower than the boiling point of the solvent in the coating liquid.

In addition to the above, the manufacturing method according to the invention of claim 4 further comprises:
The M heat material adhering to the surface of the heat storage pellets is removed in advance before the coating liquid is sprayed.

In addition to the above, the manufacturing method according to the invention of claim 5 further comprises:
The surface of the heat storage pellets is coated with fine powder that is insoluble in the heat storage material, and then the coating liquid is sprayed.

[For production]

The seepage prevention resin layer prevents the heat storage material impregnated in the heat storage pellet from seeping onto the surface of the encapsulated N heat pellet.

With the heat storage pellets suspended, a coating liquid of a seepage prevention resin is sprayed onto the heat storage pellets, so that the coating liquid adheres to the surface of the heat storage pellets, and the solvent of the coating liquid evaporates, preventing heat storage. A seepage prevention resin layer is formed on the pellet surface.

By performing the coating treatment at a temperature lower than the boiling point of the solvent of the coating liquid, the solvent evaporates from the surface of the coating liquid adhering to the surface of the heat storage berent, forming a seepage-preventing resin layer.

By removing the heat storage material adhering to the surface of the heat storage pellets in advance and then spraying the coating liquid, it is possible to prevent the pellets from sticking to each other during Ha, and preventing the pellets from flowing.

By pre-sprinkling the surface of the heat storage pellets with fine powder that is insoluble in the heat storage material and then spraying the coating liquid, it is possible to prevent the pellets from sticking to each other when floating and preventing the pellets from flowing.

〔Example〕

The heat storage material used in this invention is a so-called latent heat type material that stores and radiates heat through a phase change. Examples of the M heat material include, but are not limited to, crystalline long-chain alkyl hydrocarbons that are compatible with polyolefin resins and have a melting point and freezing point of about 5 to 50°C, crystalline higher fatty acids, crystalline higher Preferred are fatty acid esters and crystalline organic compounds (hereinafter referred to as "waxes") such as crystalline higher aliphatic alcohols. these are,
Each can be used alone or in a mixture of two or more.

The polyolefin resin used as a carrier for the heat storage material in this invention is not particularly limited, but is
As stated in the publication, polyethylene,
Polypropylene, polybutene (including polybutylene)
, crystalline polystyrene, poly(4-methyl-pentene-1), and the like. Crosslinking of polyolefin resins can be carried out by known or well-known methods such as electron beam irradiation, gamma ray irradiation, peroxide treatment, silane crosslinking, etc., as described in JP-A-62-187782. can.

The degree of crosslinking of the crosslinked polyolefin resin is such that the gel content (gel residual amount) after xylene extraction is 10 to 90% by weight.
(Hereinafter, "wt%" is simply referred to as "%j"), and more preferably 30 to 50%.If the gel content is less than 10%, the impregnated pellets For example, something soft and sticky, ``mochi-like.''
), which may make it easier for them to stick together. Furthermore, if the gel content exceeds 90%, wax impregnation may become difficult.

As the polyolefin resin, polyethylene is preferred because of ease of crosslinking, ease of impregnation, and ease of availability.

To impregnate the heat storage material, for example, heat the molten M heat material to a temperature higher than the crystal melting point of the crosslinked polyolefin resin, place the crosslinked polyolefin resin pellets therein, continue heating and stirring, and heat storage in the crosslinked polyolefin resin pellets. This is done by impregnating the material, but other methods may also be used.

When a heat storage material having good compatibility with the polyolefin resin, such as the above-mentioned wax, is used, the M heat material penetrates into the crosslinked polyolefin resin, swells the pellet, and is fixed in the resin molecules. After heating and stirring for a desired time, the pellets are taken out from the M heat material to obtain impregnated pellets, that is, N heat pellets.

The amount of heat storage material impregnated varies depending on the degree of crosslinking of the pellet, the impregnation temperature, and the time, but it is 40% based on 100% of the total weight of the crosslinked polyolefin resin pellet and the impregnated heat storage material.
The shape of the pellet, which is preferably ~85%, is generally spherical or cylindrical, but is not limited to these, and may have a flat shape, fibrous shape, cubic shape, rectangular parallelepiped shape, irregular shape, etc. You can. The shape of the pellets is preferably a shape without sharp corners in order to make the thickness of the seepage prevention resin layer of the heat storage material uniform and to make coating easier. Although the pellet size is not intended to be limited, the maximum dimension after impregnation is 0.5
It is preferable that it is Tsuru - 2ON. If the size is large, it becomes difficult to flow the pellet by air current (for example, air current), and pellets smaller than 0.5 tsuru are difficult to handle.

A ooze-preventing resin N (a ooze-preventing resin film) of the M thermal material is formed so as to cover the entire surface of the heat storage pellet obtained as described above.

As a resin for preventing seepage of heat storage materials, (a) = capable of forming a pinhole-free continuous coating film on the surface of crosslinked polyolefin resin pellets impregnated with heat material (having film formability), (bli heat material) When using the above-mentioned wax as a heat storage material, since the heat storage material has non-polar long chain alkyl groups as its entire or main component, a polar wax with excellent barrier properties that prevents seepage of the impregnated heat storage material is used. (C) A machine that can withstand the expansion and contraction of pellets caused by solidification and melting of the heat storage material due to temperature changes, and can withstand shocks and scratches caused by collisions between pellets or between pellets and turbid objects when handling pellets. It is necessary to have a strong objective.

A so-called fluid coating method is useful as a method for independently forming such a resin film on each heat storage pellet. The fluid coating method involves floating and fluidizing the M thermal pellets one by one using an air current, etc., and spraying a coating liquid of a resin that prevents heat storage material from seeping out onto the pellets in a fluid state. In this method, the solvent is removed by evaporation, etc., and a resin film is formed on the pellet surface. The coating liquid is applied in a film form to the entire surface of the heat storage material by spray painting, and the solvent of the coating liquid is evaporated by airflow or heating to form a seepage-preventing resin film, that is, a seepage-preventing resin layer. do. According to the fluid coating method, a seepage-preventing resin layer having a uniform or substantially uniform thickness is formed over the entire surface of the heat storage pellet.

The temperature of the air stream varies depending on the solvent of the coating liquid, but
The upper limit is the temperature at which the coating liquid does not dry before it is applied to the heat storage pellets, and the lower limit is the temperature at which the heat storage pellets coated with the coating liquid do not coagulate with each other without drying. preferable. Further, it is preferable that the coating treatment with the anti-bleeding resin be performed at a temperature lower than the boiling point of the solvent of the coating liquid. If the coating process is performed at a temperature higher than the boiling point of the solvent, the solvent will not only evaporate from the surface of the coating liquid, but also from within the coating liquid, resulting in the formed seepage-preventing resin layer becoming porous and causing the inside to evaporate. It may not be possible to prevent the heat storage material from seeping out.

Various types of devices for fluid coating are commercially available. For example, Fuji Sangyo's research
Fluidized bed drying/granulation/coating equipment AERO for development
M, ATICAG, fluid granulation coating machine FD-3-
5 (3121), Doria Coater, Okawara Seisakusho's fluidized bed granulation coating machine Flow Coater, super granulation coating machine Spiraflow, and Kikusui Seisakusho's VG Coco.

These fluidized coating devices suspend M-heat pellets placed in a container with airflow from below, and spray a coating liquid in the container to coat the surface of the N-heat pellets with the coating liquid. However, some of the sprayed coating liquids dry and become a solid phase before adhering to the surface of the heat storage pellets. This solid phase is in the form of thin threads like spider threads or particulates, which adhere to the surface of the heat storage pellet and prevent the formation of a uniform, pore-free seepage-preventing resin layer. Sometimes.

Therefore, by performing the coating treatment using the apparatus and method described below, it is possible to reduce the possibility that the coating liquid becomes a solid phase and then adheres to the surface of the object to be coated. Thereby, the number of pores in the film formed on the surface of the object to be coated can be reduced.

FIG. 1 schematically represents an example of an apparatus for carrying out the manufacturing method according to the present invention. This device is equipped with a coating tank 1. At the bottom of the coating tank 1, a porous plate 11 having holes smaller than the object to be coated and through which airflow can pass is arranged. In addition, coating tank 1
On the ceiling surface of the
A filter 12 having holes through which airflow can pass is arranged. An airflow A is sent into the coating tank 1 through the porous plate 11. This airflow A may be heated to a desired temperature by a heater (not shown) or the like before entering the coating bath 1, or may not be heated. Airflow A
The objects 5 to be coated are suspended in an independent state, passed through the filter 12, and discharged to the outside via the exhaust duct 20. If necessary, suspended matter is removed by the filter 12, or suspended matter and evaporated gas of the solvent of the coating liquid are removed during discharge.

A nozzle 3 is provided at the center of the lower part of the coating tank 1 to spray the coating liquid 2 from below to above. The nozzle 3 is a cylindrical flow path forming member 4 installed at the lower center of the coating tank l so as to open vertically.
It faces the opening at the bottom. The object to be coated 5, for example, M thermal pellets enters from the lower opening of the flow path forming member 4 and rises. At this time, the coating liquid 2 sprayed from the nozzle 3 or the like adheres to the object 5 to be coated to form a liquid film.

Inside the coating tank 1, there is a guiding member (for example, a guiding jig) that restricts the floating object 5 from rising.
6 is installed. The guiding member 6 is connected to the coating tank 1
, the height at which the sprayed coating liquid 2 floats and becomes a solid phase 21 due to the airflow A that suspends the object 5 to be coated, or the maximum height at which the coating liquid 2 is in the liquid phase. It is installed at the bottom. That is, the guide member 6 is installed below the part where only the solid phase 21 of the coating liquid 2 is floating.

The guide member 6 has a top-like shape, for example, and its downward surface is curved so that the airflow smoothly flows from the bottom to the top. For example, the lower center part is thin and pointed, and as you go up, it gradually gets thicker, then suddenly becomes thicker, and then the upper end gradually becomes thicker again. As a result, the cross section of the downward surface draws a gentle diagonal 3-shape shape.The upward surface does not need to be flat. is arranged so as to enter a little inside from the upper opening of the flow path forming member 4. When the guiding member 6 is installed as in this example, the upward airflow A near the center of the coating tank 1 is strong. It is better to make it happen.

From the upper opening of the channel-shaped bottom member 4, the object to be coated 5 is
and the sprayed coating liquid 2 exits. The coating liquid 2 or its solid phase 21 is carried by the airflow and quickly flows along the lower surface of the guiding member 6 into the coating tank 1.
rise within. The object to be coated 5 is restricted by the guide member 6 from rising to a region where only the solid phase 21 of the coating liquid is floating, flows laterally and falls, and floats below the guide member 6. During this time, a coating film is formed on the surface of the object 5 to be coated. Such film formation is repeated during the coating process. This makes it difficult for the solid phase 21 of the coating liquid to adhere to the surface of the object 5 to be coated, thereby reducing the number of pores in the coating layer.

Solid phase 2 of the coating liquid rising in the coating tank 1
1 is captured and removed by a filter 12 on the ceiling surface of the coating tank 1, for example.

If the solid phase 21 is actively removed, adhesion to the object to be coated 5 can be further prevented. For example, a passage 13 through which the solid phase 21 can move is provided above the guiding member 6 of the coating tank 1, and
1 is introduced into this passage 13, captured by a filter 15, etc., and removed. The passage 13 is formed, for example, by a duct 14 provided in an inverted U-shape above the ceiling surface of the coating tank 1 . A fan 16 is installed to guide the solid phase 21 to the outlet of the passage 13, and the fan 16 guides the solid phase 21.
is sucked into the passage 13. In addition, if the filter 15 that captures the solid phase 21 of the coating liquid that has entered the passage 13 is installed so that it can be freely attached and detached during the coating process, the filter 15 can be replaced as needed during the coating process, and the captured substances can be removed. This eliminates the need to stop the coating equipment. The passage 13 may lead back to the coating tank 1, but may also lead to the outside.

The channel forming member 4 prevents, for example, the sprayed coating liquid 2 from spreading laterally and becoming a solid phase below the guiding member 6, and also prevents the coating liquid 2 from efficiently adhering to the object to be coated 5. It will be installed as follows.・
Therefore, the flow path forming member 4 does not necessarily need to be provided, nor does it need to be cylindrical.

Note that the guiding member 6, flow path forming member 4, etc. are made of
It is preferable to coat them with tetrafluoroethylene resin (for example, Teflon) or to rotate them around their vertical central axes.

Although the thickness of the seepage prevention resin layer is not particularly limited, it is preferably 0.51 to 300 μm, and 5 to 200 μm.
l is more preferred. If it is too thin, the mechanical strength of this layer will decrease, and even if it is thicker than necessary, the wax barrier properties will not improve, resulting in higher costs and the disadvantage of lowering the volume ratio of the heat storage material. . The thickness of the seepage prevention resin layer can be adjusted by adjusting the amount of coating liquid sent, for example, if the relationship between the amount of coaching beans sent for spraying and its thickness is known in advance.

The seepage prevention resin layer does not necessarily need to be in close contact with or adhere to the heat storage pellets therein, and, for example, does not need to shrink as the pellets shrink.

As a result of studying the above-mentioned oozing-preventing resin and its coating method, the inventors discovered that a coating liquid made by dissolving a certain type of resin in an organic solvent, or a coating liquid consisting of an emulsion containing a certain type of resin as a main component. It has been found that the above-mentioned seepage-preventing resin layer can be formed by fluid coating.

When using a liquid made by dissolving an anti-bleeding resin in an organic solvent as a coating liquid, the resin has excellent wax barrier properties and mechanical properties as described above, and is also soluble in a volatile organic solvent. However, it must have excellent film forming properties. When using the above-mentioned wax as a heat storage material, a polar resin is preferable from the standpoint of wax barrier properties, since the heat storage material contains nonpolar long-chain alkyl groups as the entire or main component. Examples of resins that satisfy such performance include polycarbonate resin, polyurethane resin (including urethane elastomer), methacrylic resin, polyphenylene oxide, modified polyphenylene oxide (modified PPE), polysulfone, and nitrile rubber, each singly or in combination. Blends of the above are useful.

The organic solvent is preferably a solvent that is a good solvent for the oozing-preventing resin and has a boiling point of 150° C. or lower from the viewpoint of volatility. For example, tetrahydrofuran (THF)
, dichloromethane, etc., but are not limited to these. As mentioned above, the coating process is preferably carried out at a temperature below the boiling point of these solvents.

On the other hand, when using an emulsion as a coating liquid, since resin emulsions contain water as a medium, they generally have poor wettability on hydrophobic surfaces such as polyolefin resins, making uniform coating difficult. However, it was surprisingly discovered that it is possible to form a uniform film by performing fluid coating using an emulsion whose main component is a certain type of resin.

Emulsion resins are generally not composed of a single monomer, but rather a skeletal monomer (which accounts for the majority of the polymer components and determines major physical properties such as Young's modulus and water resistance).
, Adhesive hexamer (a hexamer with groups that contribute to adhesion such as carboxyl groups and amino groups), Cross-linked hexamers (a hexamer with two or more vinyl groups, which are cross-linked inside the particle through polymerization) during polymerization), reactive additives (during polymerization,
Stabilizing monomers (hydrophilic and normal, which hardly react while the emulsion is stored, but cross-link when subjected to treatment such as heating after film formation), stabilizing monomers (hydrophilic and normal, which copolymerize and help stabilize the emulsion) ), etc., and emulsions with desired performance are designed by combining these seven factors. Furthermore, pigments, dispersants, thickeners, and other additives are generally added to make this emulsion into a paint. The skeleton itself is often copolymerized with various monomers.

In this invention, the emulsion used in the coating liquid is preferably, for example, an emulsion having the following resin skeleton, but is not limited thereto. That is, it is an emulsion in which the main component of the resin skeleton is an epoxy resin, urethane resin, acrylic resin, polyester resin, NBR (tolyl rubber), vinylidene chloride resin, or a modified product of each of these resins. These emulsions can be used alone, modified, or mixed. In addition, here, emulsion is
It includes not only emulsions in the original sense, but also those called suspensions, disversions, latex, etc.

The epoxy resin emulsion is an emulsion containing an epoxy resin as a main component, and examples of its synthesis are described in, for example, JP-A-53-47454 and JP-A-54-30249. As a commercially available product, for example, there is a modified epoxy resin aqueous dispersion available from Dainippon Ink and Chemicals under the name Pateracol E-385J.

Urethane resin emulsions include, for example, prepolymers obtained from polyethers, polyesters, and diisocyanates, which are optionally emulsified using a surfactant and then chain-extended with a difunctional compound such as 1,2-diamine. There are emulsions whose main components are thermosetting resins made of a mixture of resins, blocked isocyanates, and resins with functional groups (e.g., hydroxyl groups) that are reactive with isocyanate groups. , Japanese Patent Publication No. 50-1
It is described in JP-A No. 4727, JP-A-57-159858, and JP-A-58-132051. Commercially available products include, for example, "
There are water-dispersed urethanes available under the name ``Bondaic Series'' and ionomer type water-based urethanes available under the name ``Hytran Series.''

As the polyester resin emulsion, for example, an aromatic polyester ionomer aqueous dispersion available from Dainippon Ink and Chemicals under the name "Finetex ES series" is used.

As the acrylic emulsion, for example, various copolymer resin emulsions commercially available from Dainippon Ink & Chemicals Co., Ltd. under the trade name "Boncoat" can be used.

The NBR emulsion has acrylonitrile-butadiene as its main component, and for example, carboxylated NBR commercially available from Dainippon Ink and Chemicals under the trade name "Rankstar" is used.

As the vinylidene chloride resin emulsion, for example, a vinylidene chloride resin emulsion commercially available from Kureha Chemical Industry Co., Ltd. under the trade name "Krehalon Latenox" is used.

Since the main component of these emulsions is polar resin, they have excellent wax barrier properties. Among the various emulsions mentioned above, it is preferable to select one that is formed into a film at a drying temperature of 50 to 80°C and has excellent mechanical properties. Even when an emulsion is used as the coating liquid, the coating process is carried out at a temperature lower than the boiling point of the emulsion solvent (for example, at a temperature lower than the boiling point of water).
Preferably, the temperature is lower than 00°C. In addition, the emulsion used here is in the form of particles in which the anti-bleeding resin is independently liberated in the solvent (does not turn into a solid). For this reason, while the solvent is evaporating (drying),
The loose particles fuse together to form a film, forming a seepage-preventing resin layer. At this time, if the drying speed is fast, the film may dry without being fully fused and a film with holes may be formed. Therefore, when an emulsion is used as the coating liquid, it is more preferable to perform the coating treatment at a temperature lower than the boiling point of the solvent of the emulsion and at an air drying temperature. In this way, a seepage-preventing resin film with fewer pores can be produced. The natural drying temperature is, for example, the temperature at which drying is performed without heating, and is 15
The temperature is around ~25°C.

In addition, commercially available emulsions generally have film-forming properties (film-forming properties).
Therefore, even if the same type of resin is used, the dried film may be sticky depending on the product number. When such an emulsion is used in this invention, the resin film may be sticky during fluid coating. If they stick to each other, the film may peel off from the impregnated pellets or the pellets may become unable to flow.To prevent this from happening, use a commercially available emulsion product whose dry film does not have adhesive properties. Alternatively, it is preferable to mix an emulsion with a non-sticky part number with an emulsion that gives a sticky dry film to reduce stickiness. It goes without saying that it is preferable to select a combination that is stable.

By the way, when fluid coating is performed, there is no problem if the melting point of the heat storage material impregnated into the crosslinked polyolefin resin pellets is higher than the drying temperature during fluid coating. However, if the melting point of the heat storage material is lower than the drying temperature (which is often the case), the heat storage material attached to the pellet surface is melted. For this reason, the impregnated pellets tend to stick together, making it difficult for the pellets to flow, and the partially formed coating film tends to peel off from the pellets, making it impossible to encapsulate the pellet surface with the resin film. Problems may arise. Especially when the amount of impregnation of the heat storage material is high,
There is a lot of heat storage material seeping out on the surface of the impregnated pellets, and the coating may not work properly.

According to research conducted by the inventors, it has been found that the following three methods are effective for avoiding these inconveniences.

The first method is to perform a process of washing away the heat storage material adhering to the impregnated pellets with a solvent before fluid coating. The solvent used at this time is preferably a solvent that has high solubility for the heat storage material and is highly volatile. Examples include ketone solvents such as acetone and MEK (methyl ethyl ketone), and halogenated hydrocarbon solvents such as dichloromethane and trichloroethylene (for example, "Triclene" manufactured by Toagosei Kagaku Kogyo ■). After soaking the impregnated pellets in these solvents, the M heat material adhering to the surface can be easily removed by filtering through a coarse filter.

The second method is to centrifuge the impregnated pellets to remove the heat storage material adhering to its surface before fluid coating. Centrifugation can be carried out by a known or well-known method by keeping the temperature of the impregnated pellets at a temperature higher than the melting point of the M heating material. In this case, centrifugation is preferably performed at a temperature higher than the melting point of the Li material. .

The third method is to improve the adhesion of the impregnated pellets by sprinkling fine powder onto the impregnated pellets and allowing the heat storage material adhering to the pellets to be absorbed by the fine powder. is preferably 5001 or less, and is preferably insoluble in the heat storage material.For example, minerals such as kaolin, silica sand, talc, perlite, and bentonite, white carbon, carbon black, and lead white.

Inorganic pigments such as titanium dioxide and titanium black, organic pigments such as phthalocyanine blue and quinacridone, vinyl chloride resin powder (PVC powder), polyamide resin (
(such as those sold under the trade name ``nylon'')
There are fine polymer powders such as powders, and each can be used alone or in combination of two or more.

After performing any of these first to third processes,
When the 71% exudation prevention resin coating liquid is applied by fluid coating, the surface of the crosslinked polyolefin resin pellets is not sticky, so the pellets do not flow and are prevented from sticking to each other. A continuous resin film can be easily formed on the impregnated pellets.

Examples of the present invention are shown below, but the present invention is not limited to the following examples.

In the Examples and Comparative Examples below, a silane crosslinked polyethylene resin "Linkron" commercially available from Mitsubishi Yuka was used in the form of micro pellets as the crosslinked polyolefin resin. As the wax as a heat storage material, in all cases other than Example 7, crystalline fatty acid ester "Thermotop 15" (phase change temperature 15°C) commercially available from Asahi Denka Kogyo was used; A commercially available crystalline fatty acid ester "Thermotop 25" (phase change temperature 25°C) was used. The urethane elastomer used in the coating liquid is Vandesox T-5105J from Dainippon Ink and Chemicals, and the polycarbonate is EPLIm.
``Lexan 101-701J'' was used. Among the coating emulsions, the modified urethane resin aqueous dispersion was ``EXP-382J,'' the modified epoxy resin aqueous dispersion was ``rEXP-385J,'' and the polyurethane ionomer aqueous dispersion was ``EXP-382J.'' Hytran HW340J (all three products are Dainippon Ink & Chemicals products) were used.°.

Examples 1 to 4 - Crosslinked polyethylene resin pellets (pellet size: approx. 1
The pellets are placed in wax at a temperature above the melting point (15.0°C) of 1φ 75% impregnated pellets and 8
0% impregnated pellets 4 were obtained.

A coating liquid was prepared by dissolving the resin listed in Table 1 in a predetermined amount of solvent.

Using a Fuji Sangyo fluid coating test machine (Erocoater), put 200 to 300 g of impregnated pellets into the coating machine, and blow hot air or hot air at the temperature listed in Table 1.
Alternatively, the impregnated pellets are made to flow by passing an air current at an air flow rate of 100 to 120 mF/min, and in this state, the coating liquid is sprayed to form a film having the thickness shown in Table 1 on the surface of the impregnated pellets, and the encapsulated heat storage pellets are was created.

- Comparative Example 1 - A resin film was not formed on the surface of the impregnated pellet obtained in Example 1, and the heat storage pellet was used as it was.

- Comparative Example 2 - A resin film was not formed on the surface of the impregnated pellet obtained in Example 4, and the M heat pellet was used as it was.

Example 5.6 - In Example 1, an encapsulated heat storage pellet was produced in the same manner as in Example 1 except that the coating liquid and coating conditions were as shown in Table 1.

Example 7 - Using the wax shown in Table 1, impregnation was carried out in the same manner as in Example 1 (the pellet size was different) to obtain impregnated pellets of the size shown in Table 1. After performing pretreatment to remove the wax adhering to the surface of the impregnated pellets with dichloromethane, coating was performed in the same manner as in Example 1 using the coating liquid and coating conditions shown in Table 1 to form encapsulated heat storage pellets. was created.

Example 8 - Using the wax shown in Table 1, impregnation was carried out in the same manner as in Example 1 to obtain impregnated pellets of the size shown in Table 1. After performing a pretreatment to remove the wax adhering to the surface of the impregnated pellets by centrifugation at 25°C and a centrifugal acceleration of 2000 g for 1 minute, the coating solution and coating conditions shown in Table 1 were used as described in Example 1. Coating was performed in the same manner to produce an encapsulated heat storage pellet.

Example 9 - Using the wax shown in Table 1, impregnation was carried out in the same manner as in Example 1 to obtain impregnated pellets of the size shown in Table 1. The surface of the impregnated pellets was pretreated by sprinkling fine powder talc and removing excess talc with a sieve, and then coating was carried out in the same manner as in Example 1 using the coating liquid and coating conditions shown in Table 1. A heat storage pellet was fabricated.

Example 1 In Example 2, the coating conditions were changed as shown in Table 2, and the air volume was changed from 1.6 to 2.0 m.
Encapsulated N-thermal pellets were produced in the same manner as in Example 2, except that the heating time was changed to /min.

Example 11 In Example 4, the coating conditions were changed as shown in Table 2, and the air volume was 1.6 to 2, Or#/
Encapsulated heat storage pellets were produced in the same manner as in Example 4, except that the temperature was changed to 10 minutes.

Example 12 - In Example 5, the coating conditions were changed as shown in Table 2, and the air volume was 1.6 to 2, On? /
Encapsulated heat storage pellets were produced in the same manner as in Example 5, except that the temperature was changed to 10 minutes.

Example 13 In Example 6, the coating conditions were changed as shown in Table 2, and the air volume was changed from 1.6 to 2.0 m.
Encapsulated heat storage pellets were produced in the same manner as in Example 6 except that the time was changed to /min.

Each encapsulated heat storage pellet of Examples 1 to 13, and
Regarding the heat storage pellets of Comparative Example 1.2 that are not resin-coated, the solidification (-5°C) - melting (35°C)
) was repeated for 200 cycles, the wax barrier properties were evaluated based on the weight of wax exuding from the pellets (wax iξ amount). The results are shown in Tables 1 and 2.

As shown in Table 1, each of the M heat pellets of Comparative Examples 1 and 2 showed wax exudation. In particular, in Comparative Example 2 in which the amount of wax impregnated was large, seepage was significant. In contrast,
As shown in Tables 1 and 2, each of the encapsulated thermal storage pellets of Examples 1 to 13 had a large amount of wax impregnation.
Wax: The amount of ξ output was zero. In addition, implementation 1fil
Among these, those that have been pretreated as described above before coating do not cause the pellets to stick together and form clumps during fluid coating, which may hinder the flow of the pellets or cause the film on the pellet surface to peel off. There were no inconveniences. These products also had good adhesion of the film to the pellets, and were able to form a continuous film on the pellets.

In Examples 10 and 11, it was also investigated using an electron microscope how the appearance of the seepage prevention resin layer of the obtained encapsulated heat storage pellets changed when the coating treatment temperature was lowered. The lower the temperature, the fewer pores in the seepage prevention resin layer.

In Examples 12 and 13, encapsulated heat storage pellets were obtained by setting three coating treatment temperatures: 70°C, 40°C, and 30°C. For each of the encapsulated heat storage pellets thus obtained, the solidification-melting process was repeated 2000 cycles, and then the weight of wax exuding from the pellets was examined.

As a result, as the coating treatment temperature decreases as mentioned above, the iS output of the M heat material decreases by 6% and 4%, respectively.
, decreased by 3%.

In addition, when the same coating process as each coating process of Examples 10 to 13 was performed using the apparatus shown in FIG.
It was possible to observe with the naked eye that each amount decreased. This is thought to be because during the coating process, the coating liquid becomes less likely to adhere to the surface of the heat storage pellet after it becomes a solid phase.

〔Effect of the invention〕

As described above, the encapsulated iQ pellet according to the invention of claim 1 has excellent mechanical strength, and the heat storage material does not seep onto the surface.

The method for producing encapsulated N-thermal pellets according to each of the inventions of claims 2 to 5 makes it possible to obtain encapsulated heat storage pellets that are excellent in mechanical strength and in which the heat storage material does not ooze out on the surface.

In the manufacturing method according to the third aspect of the present invention, the solvent of the coating liquid adhering to the surface of the heat storage pellet is further prevented from evaporating from the inside, and the number of pores in the seepage prevention resin layer can be further reduced.

The manufacturing methods according to the fourth and fifth aspects of the present invention can further prevent the seepage prevention resin layer from being partially formed, and can better prevent the heat storage material from seeping out.

[Brief explanation of the drawing]

FIG. 1 is a partially sectional side view showing an example of an apparatus used to carry out the method for manufacturing encapsulated heat storage pellets according to the present invention. Agent Patent Attorney Takehiko Matsumoto

Claims (1)

[Scope of Claims] 1. An encapsulated heat storage pellet comprising a crosslinked polyolefin resin pellet impregnated with a heat storage material, and a resin layer to prevent the heat storage material from seeping out is formed on the surface of the heat storage pellet. 2 A method for forming a resin layer for preventing seepage of the heat storage material on the surface of a heat storage pellet obtained by impregnating a heat storage material into a crosslinked polyolefin resin pellet, wherein the heat storage pellet is suspended independently, and the heat storage material is prevented from seeping out. A method for producing encapsulated heat storage pellets, which comprises spraying a coating liquid of a prevention resin onto the heat storage pellets to form the seepage prevention resin layer on the surface of the heat storage pellets. 3. The method for producing encapsulated heat storage pellets according to claim 2, wherein the coating treatment of the seepage prevention resin onto the heat storage pellets is performed at a temperature lower than the boiling point of the solvent of the coating liquid. 4. The method for producing encapsulated heat storage pellets according to claim 2 or 3, wherein the spray coating is performed after removing the heat storage material adhering to the surface of the heat storage pellets in advance. 5. The method for producing encapsulated heat storage pellets according to claim 2 or 3, wherein the spray coating is performed after the surface of the heat storage pellets is previously sprinkled with fine powder insoluble in the heat storage material.