JPH10318445A - Insulated piping material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully exert a sufficient thermal insulating property even with thin insulating layer by forming the insulating layer having one or more than two types of mixtures selected from a group consisting of superfine grains of silica, titanium oxide, aluminum oxide and iron oxide as a main component. SOLUTION: In this insulated piping material useful as an insulated pipe, an insulating layer having one or more than two types of mixtures consisting of superfine grains of silica, titanium oxide, aluminum oxide and iron oxide is formed. For example, in the case where it is applied to a piping consisting of two resin hot and cold water feeding pipes 1 surrounded with insulating material, the insulating material composed of polyethylene foam 2 kneaded with superfine grain powder 3 is used. In manufacturing, polyethylene pellets is knead with the superfine grain powder to form pellets of polyethylene/ superfine grains, to manufacture a sheet consisting of the polyethylene/superfine grain powder foam, and then the insulated piping material is constituted with this sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-insulating pipe, and more particularly, to a heat-insulating pipe for transporting a heat medium such as hot water, cold water, oil or the like with minimum thermal loss, and a heat-insulating pipe useful as the heat-insulating layer. About materials. The heat insulating piping material of the present invention
Specifically, it is useful as an insulated pipe used in a hot water heating device including a gas water heater and a floor heater, and in a device inside, outside, or between devices of a cooling / heating device.

[0002]

2. Description of the Related Art Insulation of a liquid supply pipe (transport pipe) for a heating medium such as hot water, cold water, oil, etc. is a technology having a long history.
At present, organic heat insulating materials (polyethylene foam, polystyrene foam, polyurethane foam, etc.) and inorganic heat insulating materials (glass wool, rock wool, foam molded products mainly composed of calcium silicate) are used.

[0003] As a technique currently used, a method of covering a resin or metal pipe (pipe) with a heat insulating material such as polyethylene foam, polystyrene foam, or polyurethane foam is generally used for heat insulation of a hot water pipe. (JP-A-1-57026, JP-A-4-26048)
No. 5). Even in a large-scale district heating / cooling system, the insulation of the hot / cold water pipe is the same (Japanese Patent Laid-Open No. 3-20536).

For applications requiring nonflammability, such as electrical applications, glass wool, rock wool, and foamed molded products mainly composed of calcium silicate are used (JP-A-3-234).
741) and other uses requiring nonflammability include calcium silicate molded products.

[0005] The heat insulating material used in the prior art described above reduces the thermal conductivity due to air bubbles, and cannot have a thermal conductivity lower than that of air in principle. Currently, there is a demand for a heat insulating material having a heat conductivity equal to or lower than that of air and its application technology.

[0006] The heat insulating property of the heat insulating pipe is determined by the thermal conductivity of the heat insulating material. Currently used heat insulating materials exhibit heat insulating properties by air or other gas-filled air bubbles, and therefore do not reach thermal conductivity equal to or lower than air, and have insufficient performance. Actually, polyethylene foam having a thickness of 12 mm is used for hot water piping, and there is a problem in workability at the time of piping (the piping cannot be provided in a narrow space). In the piping inside the equipment, this heat insulating material is an obstacle to the spread of small and small space equipment. At the same time, transportation of hot water (liquid sending)
There is still a problem in improving energy loss at the time.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a piping material having excellent heat insulating properties. An object of the present invention is to provide a piping material having a thin heat insulating layer and sufficient heat insulating properties. An object of the present invention is to provide a foamed resin having excellent heat insulating properties and suitable as a heat insulating material for a heat insulating piping material.

[0008]

The present invention comprises, as a main component, one or a mixture of two or more selected from the group consisting of ultrafine silica, ultrafine titanium oxide, ultrafine aluminum oxide and ultrafine iron oxide. The heat insulating piping material has at least one heat insulating layer. The present invention relates to one or two kinds selected from the group consisting of ultrafine silica, ultrafine titanium oxide, ultrafine aluminum oxide and ultrafine iron oxide.
A heat-insulating piping material provided with at least one foamed resin heat-insulating layer containing a mixture of two or more kinds. The present invention provides one or two kinds selected from the group consisting of ultrafine silica, ultrafine titanium oxide and ultrafine iron oxide in a resin matrix.
A foamed resin characterized in that a mixture of more than one kind is dispersed. In the present invention, “ultrafine particles” mean particles having a primary particle size of 30 μm or less.

In the present invention, instead of the conventionally used heat insulating material (thermal conductivity k = 0.04 to 0.038 W / mK), an ultrafine powder heat insulating material having a lower heat conductivity than the new air ( A heat-insulating pipe using a thermal conductivity (k = 0.021 W / mK) is used. The ultrafine powder itself is very fragile, so improve the fragility by dispersing the ultrafine particles in a small amount of binder, or solve the problem of fragility by providing a surface protective layer, and A new level of heat insulation pipe.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION By providing a heat insulating layer on the outer periphery of a pipe for transporting a heat medium, it is possible to provide a piping material with less thermal loss of the heat medium during transportation. The type, shape, and size of the pipe are not particularly limited as long as the heat medium can be transported, and can be appropriately selected according to the type of the heat medium, the application and use form of the piping material, and the like. As the pipe, for example, a metal pipe and a resin pipe can be used.

[0011] One or a mixture of two or more selected from the group consisting of ultrafine silica, ultrafine titanium oxide, ultrafine aluminum oxide and ultrafine iron oxide is used on the outer periphery of the pipe (hereinafter also referred to as "ultrafine particles"). By installing a heat insulation layer (hereinafter also referred to as “ultra fine particle heat insulation layer”),
Thermal loss (heat radiation, heat absorption) of the heat medium from around the pipe
Can be suppressed. The ultra-fine particle heat insulating layer can be individually installed (laminated) on the outer circumference of each pipe,
It can be installed to surround a bundle of two or more pipes.

As the ultrafine particle heat insulating layer, a heat insulating layer containing ultrafine particles as a main component (for example, a molded product containing ultrafine particles as a main component and ultrafine particles dispersed in a binder) or a matrix resin in which the ultrafine particles are dispersed can be used. Can be used. By using the ultrafine particles in a state in which the primary particles do not substantially contain particles having a particle diameter exceeding 30 nm, the average particle diameter is particularly 10 nm or less (usually 5 to 9 n).
By using the powder of m), good properties can be exhibited as a heat insulating material.

The ultrafine particles can be used as a mixture with a powder having a primary particle diameter of more than 30 nm within a range that does not have a fatal adverse effect on the heat insulating properties. Normal,
The ultrafine particles can exhibit good properties as a heat insulating material even when the ultrafine particles contain 10% by weight or less, preferably 5% by weight or less, particularly preferably 3% by weight or less of particles having a primary particle diameter exceeding 30 nm. it can.

As a binder for dispersing the ultrafine particles, various organic binders and inorganic binders can be used. As organic binders, thermosetting resins such as phenolic resins (resole resins, novolak resins), epoxy resins, urethane resins, polyamides,
A heat-resistant thermoplastic resin such as polyester can be used. Water glass or the like can be used as the inorganic binder.

Although not particularly limited, a good heat insulating layer can be provided usually by using a binder in an amount of about 5 to 50% by weight, preferably about 10 to 20% by weight of the ultrafine particle heat insulating layer. If the amount of binder used is small,
The effect of using the binder is low, and it becomes difficult to maintain the shape of the obtained ultrafine particle heat insulating layer. If the amount of the binder used is too large, the heat insulating property due to the ultrafine particles is reduced.

The ultrafine particles are dispersed in a solution or dispersion in which a resin or the like serving as a binder is dissolved or dispersed in an appropriate solvent, and the solvent is removed to form a molded body in which the ultrafine particles are dispersed in the binder. Can be manufactured. As the solvent for dissolving or dispersing the resin or the like as the binder, various solvents can be used in consideration of the solubility in the binder and the ease of removal (boiling point) according to the type of the binder. And various organic solvents (especially volatile organic solvents) such as esters, ketones, ethers and alcohols.

A foamed resin in which ultrafine particles are dispersed in a matrix resin can be produced by foaming a foamed resin material containing ultrafine particles. For example, when the matrix resin is a thermoplastic resin,
It can be manufactured by blending ultrafine particles and a foaming agent, melting a resin, and performing foam molding (for example, injection molding). When the matrix resin is a thermosetting resin, it can be produced by heating, foaming and curing a resin composition containing a raw material resin, ultrafine particles and a foaming agent.

The heat insulating layer of ultrafine particles has a lower thermal conductivity than a conventionally used thermal insulating material (thermal conductivity k = 0.04 to 0.038 W / mK), particularly a lower thermal conductivity than air (0.
0256W / mK or less, usually 0.015 to 0.025W
/ MK). The piping material of the present invention has at least one heat insulating layer of ultrafine particles. By providing two or more heat insulating layers of ultrafine particles, heat insulating properties can be improved. In the piping material of the present invention, the ultrafine particle heat-insulating layer can be laminated and installed with another type of heat-insulating layer. As other heat insulating layers, resin foams such as polystyrene foam, polyurethane foam and polyethylene foam, foam glass, perlite, inorganic heat insulators such as vermiculite,
A woven or non-woven fabric of organic or inorganic fibers can be used.

[0019]

In the heat-insulating piping material of the present invention, the ultrafine particles are considered to have the following effects: (1) Reduction of heat conduction in a solid: In the case of ultrafine powder, the heat-insulating area of the solid portion through which heat can be transmitted and Since the contact area between the particles is small and the heat conduction in the solid is small, it is possible to provide a heat insulating layer having a fine porous structure with small heat conduction by using ultrafine powder.

(2) Reduction of gas convection: In general porous materials, convection tends to occur as the temperature and the temperature difference increase, but the heat insulating layer using ultrafine particles has a dense concept, Since the gas does not easily flow, heat conduction is small.

(3) Reduction of radiation heat: a heat-resistant metal oxide that scatters infrared rays (for example, TiO ₂ , Al ₂ O ₃ , F
By using e ₂ O ₃ ), heat conduction of the heat insulating layer due to radiant heat can be reduced.

(4) Decrease in heat conduction in stationary gas: Most of the volume of a general porous material is occupied by gas. However, when a fine porous structure is formed by ultra-fine particles, heat conduction of gas does not occur. This is the mean free path (0
° C, 1 atm gas molecule for about 100 nm). Heat (ie, kinetic energy) between gas molecules is transferred by collision between molecules. The void formed by the ultrafine particles is smaller than the mean free path of the gas molecules (about 100 nm). In this fine void, collision between the gas molecules hardly occurs, so that gas heat conduction hardly occurs. This is a factor that reduces the thermal conductivity of the heat insulating layer using the ultrafine particles of the present invention to below air.

[0023]

The heat-insulating pipe of the present invention has a heat-insulating performance (reciprocal of the energy loss ratio in consideration of the thickness of the heat-insulating material) of at least twice (usually 2.6 to 3.0) as compared with the conventional product.
(About 4 times). This is because if the thickness of the heat insulating material is the same, the heat loss of the heat insulating pipe of the present invention due to heat radiation during transportation of the heat medium is １ ／ or less (usually 1 /
About 2.6 to 1 / 3.4).

[0024]

Embodiment 1 FIG. 1 shows a cross-sectional view of a pipe member of this embodiment. It has a structure in which two resin-made hot and cold water supply pipes (polyethylene 10A) are surrounded by a heat insulating material. The heat insulating material is obtained by kneading ultrafine powder with polyethylene foam. As a manufacturing method, polyethylene pellets and ultrafine particles were kneaded with a twin screw extruder, and a pellet of polyethylene / ultrafine particles was manufactured using a pelletizer. The weight ratio of polyethylene to ultrafine powder was 100 parts / 50 parts. The pellets produced here were processed by the same process as before using a polyethylene / ultrafine powder foam (foam) with a thickness of 7 mm.
Was prepared. The prepared sheet was used, combined with two liquid feeding pipes, and assembled into the configuration shown in FIG.

As the ultrafine powder, SiO ₂ (6) having a maximum primary particle diameter of 30 nm and an average particle diameter of 7 nm is used.
_{5.0wt%), TiO 2 (31.5wt} %), Al 2 O
₃ (2.5 wt%) and Fe ₂ O ₃ (1.0 wt%) ultrafine particles (ultrafine particles used in coil wrap type microtherm manufactured by Nippon Microtherm Co., Ltd.)
It was used. The raw material of this ultrafine particle powder is ultrafine particles (1
Secondary particles), but they are agglomerated,
The secondary particles have a size of several microns or more and can be kneaded with the resin.

Embodiment 2 FIG. 2 shows a cross-sectional view of the piping material of this embodiment. Each of the resin-made hot and cold water supply pipes (polyethylene 10A) is surrounded by a heat insulating material (thickness: 5 mm) formed by molding ultrafine powder.
Furthermore, a polyethylene foam sheet (thickness 2)
mm).

The heat insulating material is formed by adding a binder to ultrafine powder and molding. The same powder as in Example 1 was used as the ultrafine powder, and a resol resin was used as the resin binder. The ultrafine powder was dispersed in a mixed solvent solution of a resole resin, ethyl acetate, methyl ethyl ketone, and ethyl cellosolve, and evaporated and dried at low temperature as it was. According to the measurement of the weight change, the resol resin was 17 parts with respect to 100 parts of the ultrafine particle powder.

The dried product is pulverized again, filled in a mold, lightly pressurized, and then directly heated at 150 ° C. for 15 minutes to melt and harden the resol resin to obtain an ultrafine powder molded object. Obtained. The shape of the molded product is a hollow cylindrical shape. A hole having a length of 300 mm, a diameter of 20 mm, and a diameter of 10 mm passes through the center. A hot / cold water feed pipe was passed through this hole. Therefore, the thickness of the heat-insulating material of the ultrafine powder molded product is 5 mm.
It is. Two of these were arranged and covered with a polyethylene foam sheet having a thickness of 2 mm to obtain the structure shown in FIG.

Comparative Example 1 FIG. 3 shows a cross-sectional view of the piping material of this comparative example. In this comparative example, a hot and cold water supply pipe (polyethylene 10A: used in Examples 1 and 2), which is generally widely used, is used.
The book was structured to be surrounded by a conventional heat insulating material (polyethylene foam).

[Results] In order to examine the heat insulating properties of the heat insulating piping materials of Examples 1 and 2 and Comparative Example 1, each pipe was heated at 60 ° C.
Was flowed, and a thermocouple was installed on the surface of the heat insulating layer and on the surface of the liquid sending pipe inside the heat insulating layer to measure the temperature. The atmosphere around the measurement was 18 ° C. and 60% RH. The results are summarized in Table 1.

[0031]

[Table 1]

In Table 1, the heat insulating performance ratio representing the heat insulating property was defined and calculated as follows: Heat insulating performance ratio = (Thickness of heat insulating material layer of Comparative Example 1: 12 m)
m) / (thickness of heat insulating material layer of Example 1 or 2: 7 mm) ×
(Temperature difference from the atmosphere of Comparative Example 1: 12 ° C.) / (Example 1)
Or the temperature difference of 2) This numerical value represents the heat insulation performance of the example relative to the comparative example (the reciprocal of the ratio of the energy loss in consideration of the thickness of the heat insulating material).
According to Table 1, it can be seen that both Example 1 and Example 2 are heat-insulating pipes exhibiting excellent heat-insulating properties with small energy loss due to heat radiation when sending hot water.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a heat-insulating piping material of Example 1.

FIG. 2 is a schematic cross-sectional view of the heat-insulating piping material of Example 2.

FIG. 3 is a schematic sectional view of a piping material of Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid sending pipe 2 Polyethylene foam 3 Ultra fine particle 4 Polyethylene 5 Air bubble 6 Ultra fine particle heat insulating layer (ultra fine particle + binder) 7 Binder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Ayumu Yasuda Inside Kyoto Research Park Research Institute, Inc. 17 Teranicho Kyoto Research Park Kansai New Technology Research Institute

Claims (3)

[Claims] An ultrafine silica, an ultrafine titanium oxide,
A heat-insulating piping material provided with at least one heat-insulating layer mainly composed of one or a mixture of two or more selected from the group consisting of ultrafine aluminum oxide and ultrafine iron oxide. 2. Ultrafine silica, ultrafine titanium oxide,
A heat insulating piping material comprising at least one foamed resin heat insulating layer containing one or a mixture of two or more selected from the group consisting of ultrafine aluminum oxide and ultrafine iron oxide. 3. Ultrafine silica in a resin matrix,
A foamed resin characterized in that one or a mixture of two or more selected from the group consisting of ultrafine titanium oxide, ultrafine aluminum oxide and ultrafine iron oxide is dispersed.