JPS59188429A - Heat-insulating coating material having excellent execution performance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heat insulating coating material with excellent construction performance. For more information, please refer to the prevention of condensation in fluid piping such as water pipes, refrigeration equipment piping, air-conditioning equipment piping, water heater piping, etc., cold storage/thermal insulation,
It relates to a heat insulating coating material for the purpose of heat insulation.

Conventionally, tubular or sheet-shaped foams made of low-density polyethylene, cross-linked polyethylene, and cross-linked polypropylene have been known as heat-insulating coating materials for the various fluid piping mentioned above, but low-density polyethylene foams have poor heat resistance and are 70℃
It could only be used for hot water piping of about 10,000 yen, and cross-linked polyethylene had a cost of about 10,000 yen at most. Further, although the crosslinked polypropylene foam has heat resistance and can be used up to 120° C., it easily deteriorates due to contact with the metal of piping, which poses a practical problem. In response, pipe coating materials with excellent heat resistance have been developed using mixed resins of high-density polyethylene and ionomer, or mixed resins of high-density polyethylene and low-density polyethylene, and some have been put into practical use.
The heat resistance temperature is at most 110°C, and its uses are extremely...
It was limited to the department. In addition, these mixed resin foams are
Defects such as tears, wrinkles, and dents are likely to occur during construction, and it is necessary to use a separate covering material to cover the curved pipe, which takes a long time to install and has poor construction performance.

In addition, in order to improve the compressive strength, bending strength, etc. of the foam,
Foams with a specific distribution of air bubbles are known, for example, as disclosed in Utility Model Publication No. 49-3639.
No. 57 of the Publication of Utility Model, which has a thick epidermis on the surface and a layer of flat bubbles on the inside that is in contact with it.
No.-5'5063 has a structure in which the central part is radially oriented and elongated, and the peripheral part is circular (see Figure 2). However, the foams described in these publications are for the purpose of improving their strength, and if foams with the same structure as these are used for the same purpose as the present application, that is, as a heat insulating coating material for fluid piping, construction will not be possible. Occasionally, the foam layer would crack, wrinkle, dent, etc., creating two problems in practical use.

The present invention relates to a new heat-insulating coating material that solves the problems mentioned above.It has excellent heat resistance and heat insulation properties, can be coated on curved pipe parts, and has drawbacks such as tearing, wrinkles, and dents when covering pipes. Concerning heat insulating coating materials with poor construction performance.

That is, in the present invention, in a cylindrical foam made of polyethylene, the polyethylene has a density o and 940 g/c+n''
J: 0, within the range of 966 g/cm' or less, melt index O, OIg/'l O min or less 4-15.5 g
The present invention relates to a cylindrical foam, which is made of high-density polyethylene within a range of /10 minutes or less, and characterized in that the W homogeneous cell system inside the cylindrical foam layer is 2.0 mm or less.

The density of the high-density polyethylene constituting the cylindrical foam of the present invention is 0.966 g/cm at 0.940 g/cm3 or more
It is within the range of 3 or less. If polyethylene with a density of less than 0.940 is used, the maximum operating temperature of the foam will be low, and it is not preferred as a heat insulating coating material for high temperature liquid piping, which is the object of the present invention. Furthermore, high-density polyethylene with a density greater than 0.966 is undesirable because it lacks flexibility and has poor workability in curved pipe sections. Also, the apparent density is 0, 040g/cm3 or more.
It becomes difficult to achieve high foaming.

The Nord index (190' (!, measured value at a load of 2160 gr) of the high-density polyethylene constituting the cylindrical foam of the present invention is within the range of 0.01 g/10 minutes or more and 5 g/10 minutes or less. Melt index is 0.01g
If the heating time is less than 10 minutes, the surface layer tends to become uneven, the appearance is poor, and the adhesive force when applying an exterior material to the foam is undesirable.

Further, a foam made of a resin having a melt index of more than 5 g/10 minutes is not preferable because the cells do not have a closed cell structure but contain many open cells, and furthermore, the foam has poor compression recovery properties and poor workability.

The high-density polyethylene constituting the cylindrical foam of the present invention is
Density is within the range of 0°950 or more and 0.966 or less, and melt index is 0.01g/10 minutes or less.Ig/'
A time within the range of 10 minutes or less is more preferable because it has particularly excellent workability.

In the cylindrical foam of the present invention, the average cell diameter of the inside of the foam, that is, the inner layer excluding the outer surface layer and the inner layer of the cylindrical foam is 2. It is a foam of On+m or less. If the average cell diameter of the inner layer is larger than 2.0 mm, the surface layer of the foam will be more likely to break when bending pipes into curved pipe sections, such as elbows, spiral sections, etc., and the flow area will be limited. When performing construction using a cylindrical foam with a back-split shape, cracks tend to occur in the surface layer of the foam, which serves as the bending portion, which is undesirable because wrinkles, dents, and other defects occur.

On the other hand, the lower limit of the average cell diameter of the inner layer is not particularly limited, but is generally 0.2 mm or more from the viewpoint of heat insulation performance.

In particular, it is preferable that the thickness be 0.5+nm or more in order to reduce variations in the wall thickness of the cylindrical foam.

The cylindrical foam of the present invention may have any shape as long as it can cover fluid piping, and generally has a concentric circular cross section, an elliptical outer circumference, and two circular hollow parts at approximately symmetrical positions inside the foam. It is a foam body having a cross section having a cross section of 1, a glasses-shaped cross section in the form of two concentric circular cross sections joined in parallel, etc., and having an arbitrary length in the direction perpendicular to the cross section, generally 1° of the major axis of the cross section, It is a foam with a length of .

In the cylindrical foam of the present invention, the cylindrical foam layer must have a cross-sectional area of about 2 cm2 or more. The reason for this is
When insulating a foam layer for various fluids, if the cross section 111 of the foam layer is smaller than 2 cm2, the insulation performance will be poor, which is particularly the object of the present invention.
This is because the heat insulation performance for high-temperature fluids around 0°C is poor, which is not preferable. In general, 1-equipment area 2 cm
When the thickness is 2 or more, the thickness of the foam layer is 5 mm or more, and practically 10 mm to 0 mm or more is preferable.

The foam according to claim 2 of the present invention, that is, the foam in which the cells in the outer surface layer and the inner layer are flat in the direction of the surface layer, and the cells in the inner layer are substantially isotropic polyhedral, Application to piping - No damage such as cracks or wrinkles after 1 year of aging,
More preferred.

As is clear from the comparison with the conventionally known cylindrical foam of low-density polyethylene shown in the comparative example in Table 3, or the cylindrical foam of 4-combined resin of high-rich polyethylene and ethylene ionomer, the present invention If the cell structure of the high-rich polyethylene cylindrical foam of the invention is made into a twisted structure with a conventionally known foam, defects such as cracks and dents will occur during bending or bending. On the other hand, by making the cell structure of the surface layer and the inner layer as in the present invention, the second drawback can be improved.

Although the reason for this is not clear, it is presumed that by creating the cell structure described above, the stretching orientation of the cell membrane in each part is different during the foam molding process, and the durability against bending deformation is improved.

The thickness of the outer surface layer and the inner surface layer of the cylindrical foam of the present invention may be equivalent to the thickness of two to three cells laminated in the portion,
The shape of the flat bubbles in the relevant part is based on the minimum average bubble diameter.
It suffices if the long-sleeve length is 1.5 times or more and within 4 times the length, such as a rugby shape or a Go stone shape. However, it is necessary that the direction of the minimum diameter of the flat cells coincides with the direction from the inner center of the cylindrical foam toward the outer surface layer.

Further, the cells in the inner layer of the cylindrical foam of the present invention are substantially isotropic polyhedral. This inner layer is a portion excluding the surface layer and the inner surface layer. In addition, an isotropic polyhedron is one in which the average cell diameters in the radial direction parallel to the outer and inner surfaces in the cross section of the cylindrical foam and in the longitudinal direction of the foam are approximately equal to each other, or are equal to or equal to the minimum average diameter. The ratio to the maximum average diameter is 1.2 or less.

The cylindrical foam of the present invention is produced by conventionally known foaming methods, but extrusion foaming is preferred because it is excellent in continuous production of long products and production of various cross-sectional shapes.

Specifically, the resin supply port and foaming agent injection port were
A cooling device is connected to the tip of the extruder, followed by a foam molding device with a die slit that has an opening shape that matches the cross-sectional shape of the product, and the resin and foaming agent are heated under pressure and uniformly inside the extruder. The mixture is mixed with a cooling device, cooled to a temperature suitable for foam molding, and extruded into the atmosphere through a die slit to produce a cylindrical foam.

The blowing agent used is preferably a volatile organic compound, including halogenated hydrocarbons such as aliphatic hydrocarbons, chlorinated hydrocarbons, and fluorinated chlorinated hydrocarbons, alcohols, ethers,
There are esters, etc., and those selected from one combination thereof, such as propane, butane, pentane, hexyne, fl, methyl monide, methylene chloride, dichlorodifluoromethane, dichlorofluoromethane, chlorodifluoromethane, A selection of cyclothiI-lafluoroethane and trichlorotrifluoroethane is used.

More preferably, a mixed blowing agent of dichlorotetrafluoroethane and one selected from other halogenated hydrocarbons and aliphatic hydrocarbons, or a mixed blowing agent of dichlorotetrafluoroethane and one selected from other halogenated hydrocarbons and A mixed blowing agent with one selected from aliphatic hydrocarbons, containing 20 to 80 mol% of dichlorotetrafluoroethane.
It contains.

In addition, when manufacturing the cylindrical foam of the present invention, an effective modifier is used to improve the foaming behavior and to obtain a cylindrical foam of excellent quality consisting of a foam layer of 5 mm or more with little thickness unevenness. May be used.

As this modifier, general formula (I) shown below, (]1
) and (m) are preferred because they exhibit particularly excellent effects.

As a modifier, the general formula %% () (in the formula, R is an alkylene group having 1 to 5 carbon atoms, Aeyl is a hydrogen atom or an acyl group, n is an integer from 1 to 10, and X is O or 1 to 5 An integer of 2) An amine represented by the general formula (R' in the formula is a hydrocarbon group having 1 to 23 carbon atoms,
R, n, x have the same meanings as above), and polyoxyethylene represented by the general formula % (in which a, b and C are integers of 1 or more). At least one selected from polyoxypropylene block polymers is used.

Among the compounds represented by the general formulas (1), (TI) and (Ill), the compound (T) is preferred, and a particularly preferred foaming modifier is a mixture of (1) and (II). It is. (T) and (II)
) is suitably in the range of 1:4 to 4:1 by weight, and preferably in the range of 3 to 7:3.

The amount of these compounds used is in the range of 0.05 to 15 parts by weight, preferably 0.05 to 15 parts by weight, based on 100 parts by weight of polyethylene.
It ranges from 1 to 10 parts by weight.

Specific examples of the compound represented by the general formula (T) include 2-hydroxyethylamine, di-2-hydroxyethylamine, tri-2-hydroxyethylamine,
2-hydroxypropylamine, di-2-hydroxypropylamine, tri-2-hydroxypropylamine,
2-hydro2-xypropylamine, di-2-hydroxypropylamine, tri-2-hydroxypropylamine, tri-polyoxyethylamine, and ester compounds of these with fatty acids, such as tri-2-hydroxyethylamine monostearate, tri-2-hydroxy Examples include ethylamine distearate, tri-2-hydroxyethylamine tristearate, tri-2-hydroxyethylamine monolaurate, tri-2-hydroxyethylamine dilaurate, tri-2-hydroxyethylamine trilaurate, and particularly preferred ones include 2-hydroxyethylamine trilaurate. These are ethylamine, di-2-hydroxyethylamine, tri-2-hydroxyethylamine, 2-hydroxypropylamine, di-2-hydroxypropylamine, and tri-2-hydroxypropylamine. These compounds may be used alone or in combination of two or more.

As the compound represented by the above general formula (1'I),
For example, N-2-hydroxyethyl-hexanamide, N
-2-hydroxyethyl-off3 tanamide, N-2-hydroxyethyl-decanamide, N-2-hydroxyethyl-dodecanamide, N-2
-Hydroxyethyl-tetradecanamide, N-2-hydroxyethyl-hexadecanamide, N-2-hydroxyethyl-octadecanamide, N,N-di-2-hydroxyethyl-hexanamide, N,N-di-2-hydroxyethyl- Octaneamide, N,N-di-2-hydroxyethyl-decanamide, N,N-di-2-hydroxyethyl-dodecanamide, N.

N-di-2-hydroxyethyl-tetradecanamide,
N,N-di-2-hydroxyethyl-hexadecanamide, N,N-di-2-hydroxyethyl-octadecanamide, N-2-hydroxypropyl-hexanamide, N-2-hydroxypropyl-octanamide, N-
2-Hydroxypropyl-decanamide, N-2-hydroxypropyl-dodecanamide, N-2-hydroxypropyl-tetradecanamide, N-2-hydroxypropyl-hexadecanamide, N-2-human 4-roxypropyl-octadecaneamide, N , N-G2
-Hydroxypropyl-hexanamide, N,N-di-2-hydroxypropyl-octanamide, N,N-di-2-hydroxypropylhexanamide, N,N-di-2-hydroxypropyl-dodecanamide, N,N-
Di-2-hydroxypropyl-tetradecanamide, N
, N-di-2-hydroxypropyl-hexadecaneamide, N,N-2-hydroxypropyl-octadecanamide, polyoxyethylenehexanamide, polyoxyethyleneoctanamide, polyoxyethylenedecaneamide, polyoxyethyleneoctanamide, polyoxy Examples include ethylenetetradecanamide, polyoxyethylene hexadecaneamide, polyoxyethylene octadecaneamide, etc. N- (or N, N-
di) 2-hydroxyethyl-hexanamide, N-(
or N,N-di)2-hydroxyethyl-octanamide, N-(or N,N-di)2-hydroxyethyl-dodecanamide and N-1g(or N,N-di)2-hydroxypropylhexane Amide, N-(or N,N-di)2-hydroxypropyl-octanamide, N-(or N,N-di)2-
Hydroxypropyl-dodecanamide.

These compounds may be used alone or in combination of two or more.

Further, the compound polyoxyethylene-polyoxypropylene block polymer represented by the above general formula (II) can be obtained, for example, by addition polymerizing ethylene oxide to both ends of polypropylene glycol obtained by polymerizing propylene oxide. It will be done. Among these polyoxyethylene-polyoxypropylene block polymers, preferred are those in the general formula (Ill) in which a is 17 to 34, b is 7 to 90, and C is 7 to 90. These compounds may be used alone or in combination of two or more.

The cylindrical foam of the present invention has the cross-sectional shape as described above, but in order to make it easier to cover the pipes,
The cylindrical foam of the present invention may have a split shape with a cut or a notch in a part of the cylindrical cross section along its length. A film, a multilayer sheet of these materials, or a material processed with a covering material such as asphalt may be used.

The cylindrical foam of the present invention may contain a colorant, an ultraviolet absorber, an antioxidant, an antistatic agent, an adhesion improver, a lubricant, etc., depending on its use and purpose. In some cases, other resins may be included within the range where the content of high-density boron IJ-r-1) in the base resin is 80% by weight or more.

Hereinafter, the present invention will be explained in detail with reference to Examples. In the examples, parts are parts by weight. The resins used in the examples are as follows.

1. Test methods and evaluation methods in Examples of the present invention are as follows.

JIS cut out small pieces of resin that make up the cell membrane of the bullet-proof foam
Measurement was performed using a density gradient tube described in K6760.

JIS cut out small pieces of resin that make up the cell membrane of the wood foam
It was measured by the method described in K6760.

Measurement conditions were temperature 190fO, 5°C, load 216°±l.
It is og.

1 digit density of 1 body It was measured by the method described in JIS K6767.

=1-l-average''1\ A sample thinly sliced in the cross-sectional direction and length direction of the cylindrical foam was placed under a magnifying projector, and each part of the cylindrical foam (outer surface layer, inner layer, and inner layer) was examined. For each of the randomly selected bubbles, measure the length in the radial direction in the cross section of the foam, in the direction parallel to the surface and inner surface, and in the longitudinal direction of the foam, and calculate the length in each direction. The average length was determined. In the case of anisotropy, the average length in each direction was taken as the average bubble diameter in each direction, and in the case of almost isotropy, the overall average length was taken as the average bubble diameter.

If the average cell diameter is different in each part of the foam, divide it into each part (outer surface layer, inner layer, and inside) and find the average cell diameter in each part, and if the foam is homogeneous, calculate the overall average value. It was taken as the average cell diameter of the foam.

J- No. 1, Ch. When measuring the average bubble diameter, the shape of the bubbles in each part was visually observed.

-]- On a 20 cm long sample of crystalline cylindrical foam, mark lines were drawn at intervals of 10 cm in the center, and the intervals were measured with calipers. to 4
After being left for 8 hours, it was left to stand at room temperature for 24 hours, and the distance between the marked lines was measured again using a caliper to determine the rate of change from the original length. A similar test was performed by sequentially changing the temperature of the thermostatic chamber to 0. The temperature at which the rate of change was 2% was defined as the maximum operating temperature.

[Kono Nisashi] 1 A cylindrical foam having a concentric cross section with an outer diameter of 50 m+n and an average wall thickness of 10+n+n was used to evaluate the following items.

1.1 - Place a 50cm long foam perpendicular to the length of a 30mm steel pipe, fix one end of the foam, bend the other end around the steel pipe, and crack the foam. , the minimum bending angle without causing cracks, etc. was determined.

The smaller this value is, the more preferable it is, since it is possible to cover piping with a small radius of curvature or a right-angled pipe section using an elbow.

2.1 Reno: A test piece made by cutting a part of the circumference of a 10 cm long cylindrical foam in the longitudinal direction and splitting the back is pressed open from the split back part, and the foam, especially when pushed open. The cracks, cracks, etc. at the bent portion were measured and evaluated according to the following evaluation criteria.

1 Evaluation Foam situation A: There are no cracks or cracks at all.

B: There are no cracks, but some cracks occur on the inner surface layer of the foam.

A C crack occurred and the original cylindrical shape was restored. do not have.

3. Wrinkles and dents After the foam was pushed open in the same manner as in 2 above, it was returned to its original state and the condition of the outer surface layer of the foam was observed and evaluated using the following criteria.

Evaluation Foam situation A: No wrinkles or dents remain.

B: A few wrinkles will remain, but they will return to normal within a day.

C: Wrinkles remain and recover even after - days Instead, it remains as a dent.

Support-1-l-l A vertical steel pipe with an outer diameter of 30 mm and a length of 2 m was coated with a cylindrical foam having a length of 1 m that was split in the back, and evaluated according to the following criteria.

2 Evaluation Foam situation 8. The foam is held in the pipe.

B The foam does fall down a little, but the movement is gradual.

C The foam will not be retained in the piping and will be removed immediately. Fall down.

It is preferable that the foam has good recovery properties and is well retained in the piping during construction by splitting the foam, as it facilitates post-processing such as processing of exterior materials.

5. Compression recovery rate A cylindrical foam cut to a length of 5 cm was compressed in the radial direction to 80% of its outer diameter, and the recovery rate in the radial direction was determined 1 minute after release.

The larger this value is, the better the compression recovery properties of the foam itself are, and the better the appearance after applying the exterior material.

The basic properties and workability of the Komshi foam were comprehensively evaluated and evaluated using the following criteria.

Rating 3 A: Heat resistance (maximum operating temperature) 120°C or higher, and workability is all A rank.

B Heat resistance: 120°C or higher, and workability includes some B ranks.

C# Thermal temperature is lower than 120°C or there are items with C rank in the construction method.

′:″z 1, ”1 Bore diameter 65m with foaming agent injection port and resin supply port
100 parts of resin A (density 0.860, melt index 0.3), 0.5 parts of talc, polyoxyethylene-polyoxypropylene block poly-y-(a=1
7. b=7. A mixed blowing agent of 1.5 parts of c=7), 28 parts of dichlorotetrafluoroethane, and 14 parts of methylene chloride is supplied, heated to 198°C, mixed uniformly, cooled to 126°C with a cooling device, and exposed to air. A cylindrical foam was obtained by extrusion foaming. The molding die was adjusted so that the cylindrical foam had a concentric cross section with an outer fL of 5.4 mm and an inner diameter of 30 mm. The cylindrical foam obtained by the above process has an apparent density of 0.021 g/c+n'', and the average cell diameter in the outer surface layer and inner layer of the foam is 0.5 mm in the radial direction of the cylindrical foam.
, flat bubbles with an average length of 1.111 m in the surface direction, 2 ~
It forms three layers each, and the bubbles inside are almost isotropic in both the radial direction and the surface direction, with an average diameter of 1.1 mm.
Met. As a result of evaluating the maximum operating temperature and construction performance of this foam, both showed poor performance. The results are shown in Table 1, Experiment No. 1. Similarly, resin B,
The results of evaluation using Resin C are shown in Table i1. (Experiment No. 2.3 respectively) Also, for comparison, resin D and resin E
Table 1 shows the results of evaluation using and Resin F.

(Respectively, between experiments, 4, 5, 6) As is clear from Table 1, when the density of the resin constituting the foam is greater than 0966, cracks, wrinkles, -2 lumps, etc. are likely to occur during construction, and the melt index If the weight is larger than 5.5g/10 minutes, wrinkles and dents are likely to occur. Also, the density is 0,
Polyethylene smaller than 9405 had a low maximum operating temperature and poor heat resistance. Note that the density and melt index of the resin constituting the foam were measured by slicing the foam into thin pieces using a sheet slicer, and then slicing the sliced sheets in a direction perpendicular to the sheet surface repeatedly to obtain micropiece samples.

6 C-912・2 Example 1 (
A cylindrical foam having a concentric circular cross section with an outer diameter of 50 mm and an inner diameter of 30 mm was produced in the same manner as in Experiment 1) except that the amount of talc added was changed. The average cell diameter inside the foam was 0.9 mm, 1°5 mm, (hereinafter referred to as 2 Examples, Experiment N, 7., '?) and 1.7 mm (Comparative Example, Experiment N).
The heat resistance and workability of the foams of o and 10) were evaluated in the same manner as in Example 1.

These results are shown in Table 2. In Table 2,
Experiment No. 8 is the evaluation result of the same foam as in Example 1 (Experiment No. 1).

As is clear from Table 2, if the average cell diameter inside the foam is larger than 2.0cm, the minimum angle during bending will become large, and it is clear that cracks and wrinkles will occur, resulting in poor construction performance. be.

8 172- Comparative Example 3 A cylindrical foam with an outer diameter of 50 m+n and an inner diameter of 30 mm was produced by extrusion foaming in the same manner as in Example 1 (experimental experiment, 1) except that the cooling temperature of the mixed resin was 127°C. I got it. The cells in the outer and inner surface layers of the obtained foam had an average cell diameter in the radial direction of 1.1 mm and an average cell diameter in the surface direction of 1.1 mm.
The bubbles inside the foam had a substantially isotropic shape with an average cell diameter of 1.2 mm. When the construction performance of this foam was evaluated, it was found to be poor in construction performance as shown in Experiment No. 12 in Table 3.

Comparative Example 4 A cylindrical foam was produced in the same manner as in Example 1, except that 100 parts of resin G, 0.5 parts of talc, and 28 parts of dichlorodifluoromethane were used. The cooling temperature is 106°C.
It was extruded and foamed.

The cells of the obtained foam had a substantially isotropic shape in the outer surface layer, inner surface layer, and inside, and the average cell diameter was 0.9 mm.

The results of evaluating the workability of the foam are shown in Table 3. Komama, 13.

Comparative Example 5 60 parts of resin H, 40 parts of Surlyn A (registered trademark) 1706, known as an ethylene ionomer, and 0.0 parts of talc.
A cylindrical foam was produced in the same manner as in Example 1, except that 5 parts of water, 0.5 parts of water, and 28 parts of dichlorodifluoromethane were used. Note that extrusion foaming was performed at a cooling temperature of 125°C.

The cells of the obtained foam exhibited a substantially isotropic shape in the outer surface layer, inner surface layer, and inside, and the average cell diameter was 0.9 mm.

Table 3 shows the results of evaluating the workability of the foam.
4.

As is clear from Table 3, unlike conventionally known polyethylene resin foams, the foam made using the resin of the present invention has poor construction performance if it has a uniform cell structure, and the surface layer cannot have a flat structure. The preference is clear.

1

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a known polyethylene foam consisting of cells with a substantially isotropic shape, and FIG. 2 is a cross-sectional view of a known polyethylene foam with cells oriented radially in the central portion, which improves the compressive deformation bending strength. It is a cross-sectional view of a known foamed plastic pipe that is elongated and circular at the peripheral portion 11, and FIGS. 3 and 4 are cross-sectional views of the heat-insulating coating material of the present invention having excellent construction performance. 1... Heat insulating coating material 2.2'... Bubbles in the outer surface layer and inner layer 3... Bubbles in the inner layer Applicant Asahi Kasei Corporation Agent Yutaka 1 ■ Yu Yoshi 3

Claims (1)

[Claims] 1) In a cylindrical foam made of polyethylene, the polyethylene has a density of 0, 940 g/cm" or less J-0,96
Within the range of 6g/am3 or less, the melt index is 0.
A cylindrical foam characterized by being made of high-density polyethylene within a range of 0.01 g/10 minutes or more and 5.5 g/10 minutes or less, and the average cell size inside the cylindrical foam layer is 2.0 mm or less. body. 2) Cellularity of a cylindrical foam layer 1 (i is an oblate polyhedron in which the cells in the outer surface layer and the inner layer of the foam layer extend in the direction of the surface layer, and the cells in the inner layer are almost an isotropic polyhedron. The foam according to claim 1.