JP2012159098A - Thermal insulating pipe cover - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal insulating pipe cover in which the number of bubble walls in the thermal insulating pipe cover are controlled to exert higher thermal insulating properties than those of conventional covers.SOLUTION: The thermal insulating pipe cover is manufactured by winding a resin foam tape 18 and joining side edges of the resin foam tape. The resin foam tape is formed by a thermoplastic resin, and the density of the thermal insulating pipe cover is 0.02-0.09 g/cm.

Description

  The present invention relates to a heat insulating pipe cover that is used around a pipe of a refrigerator or an air conditioner. More specifically, the present invention relates to a heat insulating pipe cover having a circular shape with a uniform cross-sectional shape and high heat insulating properties.

The heat insulating pipe cover is a cylindrical heat insulating body attached so as to cover a tubular body such as a pipe (pipe) from the outside so as to cover the outer surface. For example, it is used to keep the refrigerant pipe in the refrigeration equipment, the refrigerant pipe between the refrigeration equipment cool, or to keep the pipe through which the thermal fluid flows. The heat insulating pipe cover is often formed of a thick foam material in order to obtain good heat insulating properties.
As a conventional heat insulation pipe cover, as shown in Patent Document 1, a polyethylene resin foam sheet is processed into a strip shape, then rolled in the width direction, and welded at the end face to be joined to form a pipe cover Is common.
In addition, as in Patent Document 2, the foam tape is spirally formed such that one side of the wound tape and one side of the tape adjacent thereto are abutted with each other or overlapped with each other. And a foamed inner cylinder layer formed by joining the side edges that are wound together and butted or overlapped to each other by thermal fusion, and a tape wound on the inner cylinder layer and a tape adjacent thereto. The side edges of each roll are abutted with each other, or the side edges are overlapped with each other, the foam tape is spirally wound, and the side edges that have been abutted or overlapped are heat-bonded to each other. A heat insulating pipe cover characterized by comprising a laminated cylinder with a foamed outer cylinder layer formed by bonding is also manufactured.
However, since the heat insulating pipe cover of Patent Document 1 has difficulty in making the wall thickness and shape uniform, there is a problem that the heat insulating property varies depending on the position of the pipe cover.
Further, in Patent Document 2, a cylindrical heat insulating pipe cover having a uniform wall thickness can be obtained. As in the foamed tape used as the material, a polyethylene resin cross-linked foam sheet is used as in Patent Document 1. In addition to polyethylene having a relatively high thermal conductivity, polyethylene cross-linked foam sheet tends to increase the distance between the bubble walls, making it difficult for the thermal conductivity to decrease. It was necessary to increase the thickness of the pipe cover. Here, the distance between bubbles is a distance between bubble walls adjacent in the thickness direction. For example, when the bubble is a perfect sphere, it is the same value as the bubble diameter. However, if the thickness of the pipe cover is large, the necessary space for installing the pipe becomes large, so that there is a difficulty that it is difficult to install in a small building or a detached house, for example.

Japanese Patent No. 3510364 Japanese Patent No. 3384948

  The present invention has been made in view of the above problems, and it is an object to provide a heat insulating pipe cover that exhibits higher heat insulating properties than conventional products by controlling the number of bubble walls in the thickness direction of the heat insulating pipe cover. And

The object of the present invention has been achieved by the following means.
(1) A heat insulating pipe cover manufactured by joining side edges of a wound resin foam tape, wherein the resin foam tape is made of a thermoplastic resin, and the density of the heat insulating pipe cover is 0.02 to 0.02. A heat-insulating pipe cover characterized by being 0.09 g / cm ³ .
(2) The heat insulating pipe cover according to item (1), wherein the number of bubble walls per 10 mm thickness of the heat insulating pipe cover is 80 or more.
(3) The distance between the bubble walls of the heat insulating pipe cover is 20 to 60% in the thickness direction of 10 to 100 μm, and 40 to 80% in the range of 100 to 400 μm. The heat insulating pipe cover according to item (1) or (2).
(4) The heat insulating pipe cover according to any one of (1) to (3), wherein a cross-sectional shape of the heat insulating pipe cover is a shape in which a number of strips are bundled.
(5) About the thickness direction of a pipe cover, the aspect ratio of a bubble diameter inclines from an outer peripheral side toward an inner diameter side, The heat insulation pipe in any one of the (1)-(4) term | claim characterized by the above-mentioned cover.

  The heat insulating pipe cover according to the present invention has high heat insulating properties, so that the heat insulating effect can be enhanced and the thickness of the heat insulating material can be made smaller than that of the conventional one.

FIG. 1 is a schematic representation of the extrusion system described in Example 1. FIG. 2 is an explanatory view showing a part of the porous die described in Example 1 in an enlarged manner. FIG. 3 is a schematic view of the mantle molding machine described in the first embodiment. FIG. 4 is a perspective view of the pipe cover, illustrating the flow and the thickness direction. FIG. 5 is a front view of the pipe cover. FIG. 6 is a cross-sectional view of the pipe cover taken along the line AA. FIG. 7 is an SEM photographic image showing an enlarged vertical section of the foam tape forming the pipe cover, and is also an illustration regarding a method for calculating the distance between the bubble walls and the number of bubble walls. FIG. 8 is a cross-sectional view schematically showing the cross-sectional shape of the foam tape.

The heat insulating pipe cover obtained in the present invention supplies a foaming resin to an extruder, extrudes the resin from a die and simultaneously supplies the foamed tape obtained by foaming directly to the mantle molding machine, on the mantle molding machine It is obtained by a manufacturing method in which foamed tapes are wound in parallel while the side edges of adjacent foamed tapes are heat-sealed. By using this manufacturing method, a uniform cylindrical pipe cover can be manufactured.
The relationship between the flow of the heat insulating pipe cover, the thickness direction 42 and the cross section is shown in a perspective view in FIG. 4, and the distance 71 between the bubble walls and the number of the bubble walls 72 can be calculated from FIG.

  The inner diameter of the heat insulating pipe cover can be arbitrarily set according to the outer diameter of the pipe covered with the heat insulating pipe cover, but is generally in the range of 9.52 mm to 53.98 mm. The wall thickness is preferably in the range of 10 mm to 80 mm, more preferably 20 mm to 50 mm. When the wall thickness is less than 10 mm, the heat insulating property is deteriorated, and when it exceeds 80 mm, the pipe cover becomes too large to be practical. The width and thickness of the foam tape are not particularly limited as long as they can be wound spirally, but a tape having a width in the range of 10 mm to 70 mm and a thickness in the range of 4 mm to 10 mm is easy to wind.

Although the density of a heat insulation pipe cover can be determined according to a use, it is preferable that it is 0.02-0.09 g / cm < ³ > when the softness and heat insulation of a foam are considered. When the density exceeds 0.09 kg / cm ³ , the heat insulating property is inferior, and when the density is less than 0.02 g / cm ³ , it is too soft. For example, when a copper tube is passed through the pipe cover, it is crushed by its own weight. May occur. Further, considering practicality and production stability, the density is more preferably 0.03 to 0.06 g / cm ³ .
The number of bubble walls per 10 mm thickness of the heat insulating pipe cover shown in FIGS. 4 and 5 is preferably 80 or more, and more preferably 100 or more and 2000 or less. If the number of bubble walls is too small, the ability to reflect infrared rays is inferior, so that sufficient heat insulation performance cannot be exhibited. Moreover, when it exceeds 2000 pieces, it will permeate | transmit without reflecting infrared rays, and heat insulation performance will fall. Here, the bubble wall refers to a resin wall between adjacent bubbles in the thickness direction. The number of bubble walls is the number of bubble walls in the thickness direction. The method for measuring the number of bubble walls is as follows. The number of bubble walls intersecting the straight line is enlarged and projected on a screen or monitor using a microscope or the like, and a line segment 73 is drawn in the thickness direction 42 on the projection image as shown in FIG. 72 is counted. Usually, the sample thickness is cut out and observed so as to be 10 mm. However, when the thickness is not exactly 10 mm, the number of bubble walls may be calculated in terms of the thickness of 10 mm. The number of cell walls can be adjusted to the above range by, for example, extruding and foaming a resin, mixing an appropriate amount of a foaming agent, and adjusting the extrusion temperature within an appropriate range. At this time, adjustment is facilitated by using a cell nucleating agent.

The cross-sectional shape of the foam tape preferably shows a structure in which a large number of strips 80 are bundled as shown in FIG. This strip itself is foamed. It is preferable that the stripes overlap in a close-packed structure. However, the shape is not limited to this shape, and for example, a structure that is aligned in the thickness direction 42 may be used. By taking such a structure, the portion near the bonding surface between the strips has a small distance between the bubble walls, and the central portion of the strip can easily increase the distance between the bubble walls. Here, the distance between the bubble walls refers to the inner diameter of the bubble on the line segment in the thickness direction. Further, the shape, width, and thickness of the foam tape are not particularly specified, and any foam tape may be used as long as it can be wound to join the side edges. Since the strips are closely packed, there are practically no voids.
For air bubbles contained in the heat insulating pipe cover, with respect to the distance between the bubble walls in the pipe cover thickness direction 42 to be described later, 10 to 100 μm bubbles (small bubbles A) in the thickness direction are 20 to 60%, 101 to 400 μm. The bubbles (large bubbles B) are preferably contained in a proportion of 40 to 80%. The presence of the bubbles A and the bubbles B in the above ratio makes it possible to reflect a wide range of infrared rays and improve the heat insulation. If the proportion of the small bubbles A is too large, the infrared reflection effect on the long wavelength side is diminished, and if it is too small, the infrared reflection effect on the short wavelength side is diminished.
Further, when the bubble diameter is viewed in the thickness direction, the above-mentioned heat insulating pipe cover has an inclined aspect ratio of the distance between the bubble walls (ratio of the distance between the bubble walls in the thickness direction to the distance between the bubble walls in the width direction). It is preferable. The aspect ratio may be inclined such that the inner diameter side is small and gradually increases toward the outer peripheral side, or the outer peripheral side is small and the inclination may be gradually decreased toward the inner diameter side, but particularly from the outer peripheral side toward the inner diameter side. It is preferable to have an inclination that reduces the aspect. By generating bubbles having such an inclination, it is possible to reflect a wide range of infrared rays, and there are the following effects.

The reason why the heat insulating effect of the pipe cover of the present invention is excellent is not yet clear, but is estimated as follows. In order to improve the heat insulating property of the pipe cover, the reflection of infrared rays that try to pass through the pipe cover is an effective means. An electromagnetic wave including infrared rays has a property of reflecting at an interface of objects having different refractive indexes, and the wavelength of the reflected infrared rays varies depending on the difference in refractive index and the size of the object. That is, if bubbles exist in the resin, infrared rays are reflected at the interface between the resin and air. However, for example, infrared rays emitted from a black body at 23 ° C. have a wide range of 2 to 100 μm, and when bubbles are uniform in size, only infrared rays having a certain wavelength can be reflected. As described above, it is presumed that when there is a distribution in the size of bubbles, infrared rays in a wide wavelength range can be reflected.
In order to incline the aspect ratio, for example, it can be performed by a method such as stretching or compressing only one side of the tape.

  The extruder used for extrusion foaming is not particularly limited, and a single screw extruder, an extruder in which two or more multi-screw extruders are used singly or in combination may be used. From the viewpoint of sufficiently cooling the resin temperature near the exit of the extruder and improving the expansion ratio, it is preferable to use a system in which two or more extruders are connected.

The die used for extrusion foaming is not particularly limited, and a rod die, a T die, a porous die, or the like can be used. In order to control the distance between the bubble walls, it is preferable to use a porous die.
As a method for producing a resin foam, gas foaming, chemical foaming, or the like can be used. In the case of gas foaming, as a foaming agent, in addition to an inert gas such as carbon dioxide, nitrogen gas, helium and argon, a volatile foaming agent such as butane, pentane and tetrafluoropropene may be used. In the case of chemical foaming, azodicarbonamide, sodium hydrogen carbonate, a multilayer, or the like may be used as the chemical foaming agent. Carbon dioxide gas is preferably used from the viewpoint of affinity with the resin and safety.

The thermoplastic resin used for the foam tape is not particularly limited as long as it is a resin that can be extruded and foamed. For example, polyolefin resins such as polypropylene, polystyrene, polyvinyl chloride, olefin elastomer, styrene elastomer, and polyacryl A product obtained by extrusion foaming an acid ester resin or a polycarbonate resin may be used alone or in combination of two or more. In order to achieve both foamability and heat insulation, it is preferable to use a polypropylene resin.
The thermoplastic resin may contain a cell nucleating agent having a nucleating action. Specific examples include talc and metal soap, and the amount is usually 10% by mass or less.

  An infrared shielding material may be added to the material of the foamed tape for the purpose of improving heat insulation. This material includes polystyrene, polyacrylate resin, polycarbonate, polyethylene terephthalate, polylactic acid, and organic compounds such as copolymers thereof, as well as aluminum hydroxide, magnesium hydroxide, aluminum oxide, magnesium oxide, lithium carbonate. Inorganic compounds such as titanium oxide, hydrotalcite, wollastonite, zeolite, antimony trioxide, antimony pentoxide, titanium nitride, potassium titanate, and graphite can be used, but are not limited thereto.

  In the present invention, the crystallization accelerator, antioxidant, antistatic agent, anti-UV agent, light stabilizer, fluorescent whitening agent, pigment, and dye are added to the thermoplastic resin before foaming as long as it does not affect the properties. Various additives such as a compatibilizer, a lubricant, a reinforcing agent, a flame retardant, a cross-linking agent, a cross-linking aid, a plasticizer, a thickener, and a thinning agent may be blended. Moreover, the resin containing the said additive may be laminated | stacked on the obtained thermoplastic resin foam, and the coating material containing the said additive may be coated. From the viewpoint of fire prevention, the foam is preferably flame retardant.

  An exterior tape made of a material different from the foam material, such as an aluminum film, a polyvinyl chloride film, or a polyethylene film, on the outside of the laminated cylindrical body of the heat insulating pipe cover, preferably an adhesive having an adhesive surface on one side, for example. A tape may be wound or attached in a longitudinal direction so as to improve waterproofness and integrity and improve the appearance. Pasting may be performed on the entire surface or may be performed partially. Moreover, you may use such a tape for the cylinder layer inside a laminated cylinder. The affixing method may be adhesion by an adhesive or adhesion by heat fusion. The cross-sectional shape of the inner hollow portion of the heat insulating pipe cover is arbitrary, and may be, for example, a circle, a triangle, or an ellipse.

Next, the manufacturing method of the heat insulation pipe cover which joins the end of the wound resin foam tape of the present invention is explained. The foaming agent is supplied to the extruder together with the resin, and the resin is foamed at the same time as the resin is extruded from the die. Get. That is, a foamed tape is obtained by so-called extrusion foaming.
The foamed tape obtained by extruding the resin from the die (porous die) and foamed at the same time is supplied directly (without cutting) to the mantle molding machine, and the foamed tape is melted while fusing the side edges of the foamed tape with heat. Wind in parallel. This winding is performed spirally.

  Hereinafter, a preferred specific example of a method for producing a heat insulating pipe cover according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic view showing an example of a manufacturing process.

  In FIG. 1, the extruder is a tandem system in which a first extruder 11 for heating and melting and kneading resin and a second extruder 12 for cooling the resin are connected. The first extruder 11 includes a hopper 13, and a resin as a material is supplied to the hopper 13 and heated and melted. As for the gas which is a foaming agent, the gas pressurized from the gas cylinder 14 as a source is supplied from the gas port 16 of the first extruder 11 and is sufficiently mixed (kneaded) with the molten resin in the extruder. Gas bubbles are dispersed in the resin. The molten resin and gas mixture is conveyed to the second extruder 12 and is sufficiently cooled as it travels through the flow path.

  Next, the resin and gas mixture is extruded from the perforated die 17 and foamed simultaneously. The rod-like foamed resin extruded from the perforated die 17 is fused to each other by foaming to become a foamed tape 18. The surface of the foamed tape 18 is immediately after coming out of the perforated die 17, for example It is melted lightly by a heater 19 installed in the vicinity of 18 and sent as a foamed tape 18 to a mantle molding machine 110.

  The heated and lightly melted foam tape 18 is supplied between the mantle molding machine 110 and the pressure roller 111, and is automatically wound, and is wound while fusing the melted end of the foam tape. By rotating, the heat insulation pipe cover 112 is obtained continuously.

FIG. 2 is an explanatory view showing an enlarged part 21 of the porous die 17 in which the porous 22 is formed.
As the mantle molding machine 110, a machine known per se can be used as shown in FIG. 3, and in particular, a machine having a structure in which a flexible shaft 32 is spirally wound around a mantle shaft 31 is preferably used. It is done. That is, when the flexible shaft 32 connected to the gear box 33 rotates around the axis, the resin foam tape 18 supplied from the part 21 of the perforated die 17 is wound around the mantle shaft 31. Can do. Reference numeral 111 denotes a pressure roller, which acts to reliably wind the supplied foam tape 18 around the mantle shaft 31 by its rotation.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
Measurement and evaluation of each physical property of the pipe cover samples obtained in Examples and Comparative Examples were performed by the following methods. The results are shown in Table 1.
(Measurement of number of bubble walls and distance between bubble walls)
As shown in FIG. 4, a part is cut out from the obtained pipe cover 112 to obtain the sample shown in FIG. Using the scanning electron microscope (SEM) according to the above method, a microphotograph of the cross section of the bubble film part of the sample at a magnification of 30 times was taken, and the number of bubble walls 72 per 10 mm thickness and the distance between the bubble walls were measured by the above method. 71 was obtained (see FIG. 7).

(Evaluation of thermal insulation)
In the present invention, the following method was used as a method for evaluating heat insulation. A test specimen having a length of 500 mm was cut out in the flow direction 41 of FIG. 4 from the foamed pipe cover immediately after production, and the test piece was stored in an atmosphere of 23 ° C. and 50% humidity. Ten days after production, a copper tube suitable for the test specimen was inserted and introduced into a device in which a 0 ° C. refrigerant could flow inside. This apparatus was kept for 24 hours or more in an atmosphere of 30 ° C. and 50% humidity, the surface temperature near 250 mm from the end of the test specimen was measured, and the temperature difference between the ambient temperature and the surface temperature was used as an index for evaluating heat insulation. The evaluation criteria are good (◯) if the temperature difference is less than 2 ° C., 2 ° C. or more and 2.5 or less is a practical range (Δ), and those exceeding 2.5 ° C. are defective ( X).

Example 1
Here, the system shown in FIG. 1 was used. The first extruder 11 was a Φ40 mm single screw extruder, and the second extruder 12 was a Φ65 mm single screw extruder. Polypropylene (MFR = 2) was used as the material, and carbon dioxide gas with a purity of 99% was used as the gas. As the die, a porous die 17 having the surface shown in FIG. 2 was used. The hole diameter (22 diameter) of the porous die 17 was 1 mm, and the number of holes per area of 20 mm ² was 15.
First, polypropylene was supplied to the hopper 13 of FIG. 1, and the resin was melted in the first extruder 11 set to 170 to 210 ° C. On the other hand, carbon dioxide gas whose pressure was increased to 10 MPa by the booster 15 was supplied from the gas port 16, and the resin and gas were kneaded in the first extruder 11. The mixture of resin and gas was conveyed to the second extruder 12 set to 165 to 200 ° C., and cooled uniformly as it proceeded through the extruder.
Finally, the foam tape 18 was extruded from the perforated die 17 of FIG. The pressure of the porous die 17 was 12 MPa. The extruded foam tape 18 had a parallelogram shape with a base of 20 mm and a height of 15 mm. The surface of the foamed tape 18 was lightly melted with a lyster and supplied between a mantle molding machine 110 adjusted to an outer diameter of 30 mm and a pitch of 13 mm and a pressing roller 111. The rotational speed of the flexible shaft 32 of the mantle molding machine 110 was set slightly higher than the linear speed of the foamed tape 18 to be extruded so that the foamed tape was slightly tensioned. The wound foam tape 18 was heat-sealed at the ends, and finally, a heat insulating pipe cover 112 having an inner diameter of 30 mm and a thickness of 15 mm was obtained.

(Example 2)
The experiment was conducted in the same manner as in Example 1 except that 99% of polypropylene (MFR = 2) was mixed with 1% of a cell nucleating agent (Polyslen EE207E (manufactured by Eiwa Kasei)).

(Example 3)
An experiment was conducted in the same manner as in Example 1 except that 2% of a cell nucleating agent (Polyslen EE207E (manufactured by Eiwa Kasei)) was mixed with 98% of polypropylene (MFR = 2) as a material.

In Examples 1 to 3, the density, the number of bubble walls, and the ratio were within the ranges shown above, and the evaluation values were within the acceptable range.
In Examples 4 and 5, the foam was supplied to the mantle molding machine in the same manner as in Example 1 except that the density of the foam was 0.06 g / cm ³ . Moreover, in Example 6, the foam was supplied to the mantle molding machine in the same manner as in Example 1 except that the density of the foam was 0.07 g / cm ³ . The results of Examples 4 to 6 were as shown in Table 1 below.
In Comparative Example 1, the foam was supplied to the mantle molding machine in the same manner as in Example 1 except that the density of the foam was 0.1 g / cm ³ . However, in this case, since the density was larger than 0.09 g / cm ³ , it was rejected as shown in Table 1 below.

11 First Extruder 12 Second Extruder 13 Hopper 14 Gas Cylinder 15 Booster 16 Gas Port 17 Porous Die 18 Foam Tape 19 Heater 22 Hole 31 Mantle Shaft 32 Flexible Shaft 33 Gear Box 110 Mantle Molding Machine 111 Pressing Roll 112 Heat Insulating Pipe Cover

Claims (5)

A heat insulating pipe cover manufactured by joining side edges of a wound resin foam tape, wherein the resin foam tape is made of a thermoplastic resin, and the density of the heat insulating pipe cover is 0.02 to 0.09 g. A heat insulating pipe cover characterized by being / cm ³ .   2. The insulated pipe cover according to claim 1, wherein the number of bubble walls per 10 mm thickness of the insulated pipe cover is 80 or more.   The distance between the bubble walls of the heat insulation pipe cover is 20 to 60% in the thickness direction of 10 to 100 μm, and 40 to 80% in the range of 100 to 400 μm. The heat insulation pipe cover of 1 or 2.   The heat insulating pipe cover according to any one of claims 1 to 3, wherein a cross-sectional shape of the heat insulating pipe cover is a shape in which a number of strips are bundled.   The heat insulating pipe cover according to any one of claims 1 to 4, wherein the aspect ratio of the bubble diameter is inclined from the outer peripheral side toward the inner diameter side in the thickness direction of the pipe cover.