JP2000352476A - Cylindrical foam body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve fitting execution efficiency and dimensional stability by forming a foam body made by a cross-linking foam body mainly composed of propylene thermoplastic elastomer. SOLUTION: A cylindrical foam body is formed by a propylene thermoplastic elastomer cross-linking foam body. When the outer peripheral surface thereof is coated with olefin resin cross-linking foam body, the mechanical strength of the cylindrical foam body is improved. The foaming resin composite is supplied to an extruder, and fused and kneaded at 180-190 deg.C to extrude a foaming resin sheet. Electron beams of 2.2 Mrad are applied to both surfaces of the foaming resin sheet to perform cross-linking, and the foaming resin sheet is supplied to a hot air foaming furnace kept at about 280 deg.C to be heated and foamed, thereby obtaining a reactor TPO cross-linking foam body 4.5 mm thick and having a foaming magnification of about 35 times. Seven sheets of reactor TPO cross-linking foam body are provided, and three of them are laminated by heat and cut to a width of 168 mm to form a three-layer laminated sheet, and the sheet is supplied to a forming metal mold to be formed cylindrical.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a tubular foam suitable for use as a heat insulating material for pipes, which is excellent in terms of workability of being inserted into the outer peripheral surface of a pipe and having excellent dimensional stability after the work.

[0002]

2. Description of the Related Art Conventionally, insulation work on refrigerant pipes for freezing and refrigeration is often performed simultaneously with pipe work. And
The heat insulation tube used for the heat insulation work of the refrigerant pipe for freezing / refrigeration can be easily inserted into the outer peripheral surface of the straight pipe, and easily inserted into the outer peripheral surface of the rigid curved pipe. The workability of inserting into the outer peripheral surface of the pipe such that it can be fitted, the workability of being able to be cut in accordance with the shape of the pipe, and the dimensional stability after being fitted to the pipe, for example, the pipe support It is required that the compression creep property due to the load of the pipe in Example 1 is small, and the dimensional change rate of heating at high temperatures such as 100 to 120 ° C. during the defrosting operation is small.

As such heat insulating tubes, rubber heat insulating tubes (see JP-A-51-110753 and JP-A-52-109652) and heat insulating tubes made of a low-density polyethylene cross-linked foam are provided. ing.

[0004] However, the above rubber insulation tube is excellent in the workability and workability of insertion into a pipe, but is inferior in dimensional stability. There is a problem in that settling occurs in the heat-insulating tube, exposing the internal piping, and condensing on the outer peripheral surface of the piping.

Further, the heat insulating tube made of the low-density polyethylene cross-linked foam is inferior in flexibility and is inferior in the workability of insertion into a curved tube. A slit is formed to penetrate the inner and outer surfaces in the length direction, and a piping method is adopted in which a pipe is inserted into the heat insulating tube through the slit portion. There is a problem that the heat insulation effect may be insufficient at the slit due to the formation of the slit.

[0006]

SUMMARY OF THE INVENTION According to the present invention, even a curved pipe can be easily and reliably inserted into the outer peripheral surface thereof. A tubular foam suitable for a heat insulating material for a refrigerant pipe having excellent dimensional stability after being fitted is provided.

[0007]

The tubular foam of the present invention comprises:
It is characterized by comprising a crosslinked foam mainly composed of a propylene-based thermoplastic elastomer. The propylene-based thermoplastic elastomer is not particularly limited as long as a foam can be obtained, and examples thereof include a reactor-type propylene-based thermoplastic elastomer obtained by multi-stage polymerization of a propylene-based resin and ethylene-propylene rubber. Can be The propylene-based thermoplastic elastomer includes a low-density polyethylene, a high-density polyethylene, an ethylene-vinyl acetate copolymer, an olefin-based elastomer, and a linear chain as long as the flexibility and heat resistance of the obtained tubular foam are not impaired. Low-density polyethylene, polypropylene or the like may be added.

The range in which the flexibility and heat resistance are not impaired is
For example, when adding a linear low-density polyethylene, a low-density polyethylene, etc., if the addition amount is large, the flexibility is reduced and the insertion workability is reduced. When adding polypropylene or the like, if the addition amount is large, the flexibility is reduced, and the insertion workability is reduced. Therefore, the addition amount is 30% by weight or less. When the ethylene-vinyl acetate copolymer is added, the added amount is Increases, the heat resistance and the insertion workability decrease.
% By weight or less.

As the propylene-based thermoplastic elastomer, those which exhibit the following characteristics when subjected to temperature separation elution fractionation by a cross fractionation method are preferred. That is,
If the amount of resin eluted at 0 ° C. or more and 10 ° C. or less is large, the heat resistance of the obtained foam may be insufficient, and dimensional stability may be reduced. Since the workability of inserting the tubular foam into the pipe may be reduced, the total propylene-based thermoplastic elastomer may have a thickness of 30 to 70%.
%, More preferably 35 to 60% by weight.

If the amount of resin eluted at a temperature higher than 10 ° C. and 60 ° C. or lower is large, an elution component at a temperature of 0 ° C. or higher and 10 ° C. or lower and an elution component at a temperature higher than 60 ° C. and 130 ° C. or less will be obtained. Since it may be difficult to achieve both the flexibility and heat resistance of the tubular foam at the same time, the amount is preferably 0 to 30% by weight, more preferably 0 to 20% by weight.

If the resin elution amount is higher than 60 ° C. and lower than 130 ° C., if the amount is large, the flexibility of the obtained tubular foam may be reduced, and the workability of insertion into a pipe may be reduced. Since the heat resistance and the dimensional stability of the obtained tubular foam may be reduced, the weight is preferably 15 to 65% by weight, more preferably 20 to 55% by weight.

When the weight average molecular weight is large, the productivity of the foam, that is, the extrudability may be reduced.
When it is small, the elongation and heat resistance of the obtained tubular foam may be reduced, and the workability of inserting into a pipe and the dimensional stability may be reduced, so that 80,000 to 500,000 is preferable.

The above-mentioned cross fractionation method is performed by the following method. That is, in the cross fractionation method, the propylene-based thermoplastic elastomer is first dissolved in o-dichlorobenzene at 140 ° C. or at a temperature at which the propylene-based thermoplastic elastomer is completely dissolved, and this solution is cooled at a constant rate and prepared in advance. A thin polymer layer is formed on the surface of the inert carrier in the order of high crystallinity and high molecular weight. Next, the temperature is raised continuously or stepwise, the concentrations of the components eluted sequentially are detected, and the knitting distribution (crystallinity distribution) is measured.
This was eluted by elevating the temperature (TREF = Temperature Risi
ng Elution Fractionation).

Along with the temperature-rise elution fractionation, the molecular weight and molecular weight distribution of the sequentially eluted components are measured by high-temperature GPC. In the present invention, the temperature rising elution fractionation part and the high temperature GPC (SEC = Size Exclusion Chromatogra
ph) as a system (for example, "CF" manufactured by Mitsubishi Yuka Co., Ltd.
The above data is measured using "CT-150A type").

If the rate of change of the heating dimension of the above-mentioned tubular foam is large, when the tubular foam is used by being fitted to the pipe, when the surface temperature of the pipe becomes around 120 ° C. An unexpected situation such as fusion of the tubular foam to the surface occurs, that is, heat resistance may be reduced, and 5%
Or less, more preferably 4% or less.

The heating dimensional change rate is JIS K6.
It refers to a value measured at a temperature of 110 ° C. in accordance with 767, and specifically, the upper and lower surfaces are parallel and 150 mm in length and 1 in width.
A 50 mm square flat plate is prepared. A square is drawn in the center of the flat plate by drawing a straight line parallel to each of the four outer circumferential edges of the flat plate on an inner portion only 25 mm from each of the four outer circumferential edges of the flat plate, and the center of the opposite side of the square is drawn. Draw a crosshair in the square by connecting the parts. Then, measure the length of each side of the square and the length of two lines connecting the opposite sides of the square,
The average is obtained, and this value is used as the initial dimension.

Then, the test piece was placed horizontally in a hot air circulating dryer in which the flat plate was kept at 110 ° C., heated for 22 hours, taken out, and left for 1 hour to leave each side of the square. And the length of two lines connecting the opposite sides of the square are measured, the average thereof is determined, and this value is defined as the dimension after heating, and the heating dimensional change rate is calculated by the following equation.

(Rate of change in heating dimension) = 100 × | [(dimension after heating−initial dimension) / (dimension after heating)] |

When the Young's modulus in the length direction and the radial direction of the above-mentioned tubular foam is high, the flexibility of the obtained tubular foam is reduced, and the workability of insertion into the outer peripheral surface of the curved pipe is reduced. In some cases, when the content is low, the moldability during molding of the tubular foam may decrease. Therefore, the content is preferably 0.5 to ¹² kgf / cm ^{2, and} more preferably 1 to 10 kgf / cm ² .

In the present invention, the Young's modulus is defined as JI
A tensile strength-strain curve is determined by a tensile force test specified in SK6767, and the gradient value of a linear portion in an initial rising region of the curve is referred to. The test piece shall be a JIS No. 1 dumbbell collected from a cylindrical foam. The Young's modulus in the length direction of the tubular foam refers to the Young's modulus in the surface direction of the test piece, and the Young's modulus in the radial direction refers to the Young's modulus in the thickness direction of the test piece.

When the expansion ratio of the propylene-based thermoplastic elastomer crosslinked foam is high, the heat insulation performance and mechanical strength may be reduced if the expansion ratio is high.
20 to 50 times is preferable, and 25 to 45 times is more preferable, since the workability of insertion into the outer peripheral surface of the pipe may be deteriorated. The expansion ratio of the foam in the present invention is JI
It is measured according to SK6767.

A lubricating powder is applied or sprayed on the inner surface of the propylene-based thermoplastic elastomer crosslinked foam,
The workability of inserting the tubular foam into the pipe may be improved.

Further, the outer peripheral surface of the propylene-based thermoplastic elastomer crosslinked foam may be embossed,
When embossing is performed in this way, it plays a role of a non-slip when the tubular foam is inserted into the outer peripheral surface of the pipe, and is suitable.

Further, the outer peripheral surface of the propylene-based thermoplastic elastomer crosslinked foam may be coated with a soft olefin-based resin film as long as the processability of the tubular foam is not impaired.

The outer peripheral surface of the above-mentioned tubular foam may be entirely coated with an olefin-based resin cross-linked foam, and with such a configuration, the mechanical strength of the tubular foam can be improved. For example, even when used in a part to which a large load is applied, such as a pipe support part, there is no unexpected situation such as a backlash.

As the olefin resin, for example,
Low density polyethylene, high density polyethylene, ethylene-
Vinyl acetate copolymer, ethylene-acrylic acid copolymer,
Examples include a copolymer of ethylene and an α-olefin, a copolymer of ethylene and an α-olefin using a metallocene catalyst, and the like, and these may be used alone or in combination. In addition, as said alpha-olefin, 1-butene,
1-pentene, 1-hexene, 1-octene, 4-methyl-1-pentene, and the like.

When the expansion ratio of the crosslinked olefin resin foam is large, the mechanical strength of the obtained tubular foam may decrease, and when the expansion ratio is small, the crosslinked olefin resin foam becomes hard, Since the expansion and contraction of the propylene-based thermoplastic elastomer cross-linked foam of the flexible inner layer is suppressed, and the workability of insertion into the outer peripheral surface of the pipe may be reduced,
0 times is preferable, and 25 to 50 times is more preferable.

Further, the outer peripheral surface of the crosslinked olefin resin foam may be embossed. When the embossing is performed as described above, the outer peripheral surface of the tube is prevented from slipping when the cylindrical foam is inserted into the outer peripheral surface of the pipe. It plays a role of and is suitable. Further, the outer peripheral surface of the crosslinked olefin resin foam may be coated with a soft olefin resin film as long as the workability of the cylindrical foam is not impaired.

Next, a method for producing the above-mentioned tubular foam will be described. First, a method for producing a tubular foam made of a propylene-based thermoplastic elastomer cross-linked foam whose outer peripheral surface is not coated with the olefin-based resin cross-linked foam will be described. As a method for producing such a tubular foam, a conventionally used method for producing a foam is employed. For example, a propylene-based thermoplastic elastomer, a pyrolytic foaming agent, a crosslinking aid, if necessary, A foaming aid, an antioxidant, a foamable resin composition containing a lubricant and the like are supplied to an extruder, melt-kneaded and extruded from the foamable resin sheet. Crosslinking is performed by irradiating ionizing radiation such as X-rays, α-rays, β-rays, and γ-rays, and then the foamable resin sheet is heated and foamed to obtain a plate-like crosslinked foam. A method for producing a tubular foam by forming the plate-like cross-linked foam into a cylindrical shape and integrating opposing both end surfaces by appropriate means such as heat fusion. A propylene-based thermoplastic elastomer, a pyrolytic foaming agent, a peroxide, and, if necessary, a foaming resin composition containing a foaming aid, an antioxidant, a lubricant, etc., are supplied to an extruder and melted. After kneading and extruding the foamable resin sheet,
The foamable resin sheet is heated and foamed simultaneously with crosslinking to obtain a plate-like crosslinked foam. Then, a method of producing the tubular foam by forming the plate-like crosslinked foam into a cylindrical shape and integrating the opposing end faces with each other by an appropriate means such as heat fusion is exemplified.

Depending on the desired thickness, a plurality of the above plate-like crosslinked foams may be laminated and then formed into a cylindrical shape.

The pyrolytic foaming agent is not particularly limited as long as it has been conventionally used in the production of foams. Examples thereof include azodicarbonamide, hydrazodicarbonamide, barium azodicarboxylate, Nitrosoguanidine, p, p ^, -oxybisbenzenesulfonylsemicarbazide, benzenesulfonylhydrazide, N, N
^, -Dinitrosopentamethylenetetramine, toluenesulfonylhydrazide, 4,4-oxybis (benzenesulfonylhydrazide), azobisisobutyronitrile and the like. Among them, the decomposition temperature is 180 to 270 ° C.
Is preferred.

The amount of the pyrolytic foaming agent added is
It is appropriately adjusted according to the desired expansion ratio of the crosslinked foam. However, if the amount is too large, the foam may be broken, and if the amount is small, the foam may not be foamed. It is preferably from 40 to 40 parts by weight, more preferably from 4 to 25 parts by weight.

As the crosslinking aid, generally used polyfunctional monomers and monofunctional monomers are used, for example, divinylbenzene, trimethylolpropane trimethacrylate, 1,9-nonanediol dimethacrylate, 10-decanediol dimethacrylate, triallylic acid triallyl ester, triallyl isocyanurate, ethylvinylbenzene, neopentyl glycol dimethacrylate, 1,2,4-benzenetricarboxylic acid triallyl ester, 1,6-hexanediol dimethacrylate , Lauryl methacrylate, stearyl methacrylate and the like, which may be used alone or in combination.

If the amount of the crosslinking aid is small, the crosslinking density becomes insufficient and a homogeneous crosslinked foam may not be obtained. If the amount is large, the crosslinking density increases and the flexibility of the crosslinked foam increases. May decrease, so that the total amount of resin is 100
The amount is preferably 0.5 to 10 parts by weight, and more preferably 0.5 to 10 parts by weight.
8 to 6 parts by weight are more preferred.

The degree of crosslinking by ionizing radiation is as follows:
The gel fraction is adjusted as a guide, as the gel fraction,
If it is large, the moldability of the crosslinked foam may decrease,
Also, when the particle size is small, the bending strength of the crosslinked foam may decrease. Therefore, the amount is preferably adjusted to 30 to 70% by weight, more preferably 40 to 65% by weight. 1 to 20 Mrad.

In the present invention, the gel fraction means a value measured by the following method. First, a predetermined amount of the crosslinked foam was weighed, and was placed in 25 ml of xylene at 120 ° C. for 24 hours.
After soaking for an hour, the mixture is filtered through a 200-mesh stainless steel wire gauze, and the insoluble matter on the wire gauze is vacuum-dried. Next, the weight of the vacuum-dried insoluble matter is weighed, and the gel fraction is calculated by the following equation. [Gel fraction (%)] = (weight of insoluble matter / weight of weighed crosslinked foam) × 100

The peroxide is not particularly limited as long as it is used for crosslinking a foam.
Isobutyl peroxide, dicumyl peroxide,
2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3,1,3-bis (t-butylperoxyisopropyl) benzene, t-butylcumyl peroxide, di-t-butylperoxide Oxide, t-butylperoxybenzoate, cyclohexane peroxide, 1,1-bis (t-butylperoxy) cyclohexane, 1,1-bis (t-butylperoxy) 3,3
5-trimethylcyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,4-bis (t-butylperoxy) bellate, benzoyl peroxide, cumylperoxy neodecaneate, 5
-Dimethyl-2,5-di (benzoyloperoxy) hexane, t-butylperoxyisopropyl carbonate, t-butylperoxyallyl carbonate, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) Butane, di-t-butylperoxyisophthalate, t-butylperoxymaleic acid and the like.

If the amount of the peroxide is too small, the crosslinking density is insufficient and the shear viscosity required for foaming cannot be obtained. If the amount is too large, the crosslinking density becomes too high and foaming may not occur. 0.1 to 10 parts by weight is preferable for 100 parts by weight.

Next, a method for producing a tubular foam obtained by coating a crosslinked olefin resin foam on the outer peripheral surface of a crosslinked foam of a propylene-based thermoplastic elastomer will be described.
As a method for producing such a tubular foam, a conventionally used production method is employed. For example, while producing a tubular propylene-based thermoplastic elastomer cross-linked foam in the above-described manner, the propylene-based thermoplastic elastomer is used. A plate-like crosslinked foam of an olefin resin is produced in the same manner as in the case of the plastic elastomer crosslinked foam. Then, the propylene-based thermoplastic elastomer cross-linked foam is formed by heating the whole surface of the olefin-based resin cross-linked foam and covering the entire outer peripheral surface of the tubular propylene-based thermoplastic elastomer cross-linked foam. A method for producing a tubular foam in which an outer peripheral surface of a body is coated with an olefin-based resin crosslinked foam is exemplified.

The thickness ratio between the two layers of the propylene-based thermoplastic elastomer cross-linked foam and the olefin-based resin cross-linked foam is such that the thickness of the propylene-based thermoplastic elastomer cross-linked foam is large. And, the mechanical strength of the obtained tubular foam may be reduced, and if the thickness of the propylene-based thermoplastic elastomer crosslinked foam is thin, the workability of inserting the obtained tubular foam into a pipe can be improved. From 1: 9 to 4:
6 is preferred.

[0041]

Since the tubular foam of the present invention is formed from a propylene-based thermoplastic elastomer crosslinked foam, it is excellent in flexibility and can be smoothly applied to, for example, a large bent pipe such as 90 °. In addition, it is possible to smoothly and easily perform the work of inserting the cylindrical foam into the outer peripheral surface of the curved pipe, and it is excellent in heat resistance. Even when the pipe becomes hot due to the above, it does not shrink inadvertently, so that after the tubular foam is fitted on the curved pipe, the inner curved pipe is inadvertently exposed. No surprises occur.

When the cross-linked olefin-based resin foam is coated on the outer peripheral surface of the cross-linked foam of propylene-based thermoplastic elastomer, the mechanical strength of the cylindrical foam can be improved. However, even when used in a portion to which the addition is applied, there is no unexpected situation that the tubular foam is sagged.

[0043]

EXAMPLES In Examples 1 to 14 and Comparative Examples 1 to 6, the following resins were used. Reactor TPO: ethylene-propylene random copolymer obtained by multistage polymerization (flexural modulus = 900 j)
g / cm ² , melt index = 0.45 g / 10 min (temperature: 190 ° C., load: 2.degree. C. based on JIS K7210)
Measured under conditions of 16 kgf), density = 0.88
g / cm ³ , propylene content = 30% by weight, the resin elution amount from 0 ° C. to 10 ° C. is 48% by weight, and exceeds 10 ° C.
17% by weight at 0 ° C or less, 3% at 60 ° C or more and 130 ° C or less
5% by weight, weight average molecular weight = 310,000)

PP: ethylene-propylene random copolymer (melt index = 2 g / 10 min (JIS K
Measured under the conditions of a temperature of 190 ° C. and a load of 2.16 kgf), density = 0.90 g / cm ³ )

HDPE: high-density polyethylene (melt index = 6.5 g / 10 min (measured under the conditions of 190 ° C. under a load of 2.16 kgf based on JIS K7210), density = 0.957 g / cm ³ )

LDPE: low density polyethylene (melt index = 4 g / 10 min (measured under the conditions of 190 ° C. under a load of 2.16 kgf based on JIS K7210), density = 0.92 g / cm ³ )

LLDPE: Linear low-density polyethylene (melt index = 8 g / 10 min (JIS K72)
Measured under the conditions of a temperature of 190 ° C. and a load of 2.16 kgf based on No. 10), density = 0.91 g / cm ³ )

EVA: ethylene-vinyl acetate copolymer (melt index = 2.5 g / 10 minutes (JIS K
Measured at a temperature of 190 ° C. under a load of 2.16 kgf) based on G.7210), density = 0.94 g / cm ³ ,
(Vinyl acetate content = 19% by weight)

(Examples 1 to 6 and Comparative Examples 1 to 6) Reactors TPO, PP, HDPE,
A foamable resin composition comprising LDPE, LLDPE, EVA, azodicarbonamide, 1,10-decanediol dimethacrylate and an effective amount of 2,6-di-t-butyl-4-methylphenol is supplied to an extruder. 180 ~
The foamable resin sheet was extruded by melt-kneading at 190 ° C.
After irradiating a 2.2 Mrad electron beam to both sides of the foamable resin sheet to perform a cross-linking treatment, the foamable resin sheet is supplied to a hot-air foaming furnace maintained at about 280 ° C. and heated to foam. A reactor TPO crosslinked foam having a thickness of 4.5 mm and an expansion ratio of about 35 was obtained.

Seven crosslinked reactor TPO foams obtained as described above were prepared, three of them were thermally laminated, and then cut to a width of 168 mm to form a three-layer laminated sheet. It is formed into a cylindrical shape (tube shape) by supplying it to a mold, and the opposite end faces are heat-sealed and integrated by passing through a sealing blade at 350 ° C. to have an inner diameter of 26.5 mm and a thickness of 13.5 mm. Was obtained. Next, the remaining four sheets are laminated after heat lamination and cut to form a four-layer laminated sheet having a width of 285 mm. One surface is heated to about 200 to 450 ° C. with hot air and a heater, and the heated surface is further placed on the outer periphery of the three-layer tube. It was wound and heat-sealed by passing the facing end faces through a seal blade at 350 ° C. to obtain a seven-layer tubular foam. The inner diameter of the obtained tubular foam was 26.5 mm, and the thickness was 32 mm.

The expansion ratio, Young's modulus, and heating dimensional change of the sheet obtained by laminating seven crosslinked reactor TPO foams were as shown in Table 1. The insertability of the obtained tubular foam was evaluated, and the results are shown in Table 1.

(Examples 7 to 14) Reactors TPO, LLDPE, azodicarbonamide, 1,10-decanediol dimethacrylate, and an effective amount of 2,6-di-t-butyl- The foamable resin composition comprising 4-methylphenol is supplied to an extruder,
The foamable resin sheet was extruded by melt-kneading at ~ 190 ° C. After irradiating a 2.2 Mrad electron beam to both sides of the foamable resin sheet to perform a cross-linking treatment, the foamable resin sheet is supplied to a hot-air foaming furnace maintained at about 280 ° C. and heated to foam. And a reactor TPO crosslinked foam having a thickness of 5 mm and an expansion ratio shown in Table 2 was obtained.

The two reactor TPO crosslinked foams obtained as described above are laminated and integrated in a state of being overlapped by heat fusion to obtain an inner layer laminate, and this inner layer laminate is supplied to a molding die. To form a cylindrical shape (tubular shape), and the opposite end faces are heat-sealed and integrated by passing through a 350 ° C. seal blade.
An inner tube having a thickness of 7 mm and a thickness of 10 mm was obtained.

On the other hand, a predetermined amount of the foamable resin composition comprising LDPE and azodicarbonamide shown in Table 2 was supplied to an extruder and melt-kneaded at 180 to 190 ° C. to extrude a foamable resin sheet. 5Mr on both sides of foaming resin sheet
After irradiating with an electron beam of ad and performing a cross-linking treatment, the foamable resin sheet was supplied to a hot-air foaming furnace maintained at about 220 ° C., heated and foamed, and the thickness was 5 mm and shown in Table 2. A low density polyethylene crosslinked foam having an expansion ratio was obtained.

The two low-density polyethylene crosslinked foams obtained as described above were laminated and integrated in a state where they were overlapped by heat fusion to obtain a laminate for an outer layer. One surface of the laminate for the outer layer was heated at 300 ° C. After heating for 1 second with hot air, the tube was immediately wound around the outer surface of the inner layer tube, and both end surfaces were heat-sealed and integrated by passing through a seal blade at 350 ° C. The low-density polyethylene crosslinked foam was integrated in the same manner as above to obtain a cylindrical foam having an inner diameter of 27 mm and a thickness of 30 mm.

The obtained tubular foam was evaluated for insertability, workability and sag. The results are shown in Table 2. (Evaluation) The insertability, workability and set of the tubular foam obtained above were measured by the following methods.

(Embedding workability) A copper pipe (curvature radius = 50R, outer diameter = 25.4 mm) bent at 90 ° by a bender is fixed in a plane L shape, and a length of 1 m from one end of the copper pipe. The tubular foam was fitted to the bent portion of the copper pipe by a method of pulling in the tubular foam with both hands. The workability at that time was judged based on the following criteria.・: The tubular foam could be easily fitted to the bent portion of the copper tube. Δ: The tubular foam could be fitted onto the bent portion of the copper tube, but it required a force. X: The tubular foam could not be inserted into the copper tube.

(Workability) The workability when the tubular foam was cut in the radial direction with a cutter was judged according to the following criteria. ○ ・ ・ Cutting was possible in the radial direction of the cylindrical foam and was not required much force △ ・ ・ Cut was possible in the radial direction of the cylindrical foam Required to some extent. X: The cut surface of the cylindrical foam was uneven, and it could not be cut smoothly.

(Set) The tubular foam was cut into a length of 100 mm, a load of 2 kg was applied to the tubular foam in the radial direction for 7 days, and the thickness change rate of the tubular foam after the removal of the load was measured. did.

[0060]

[Table 1]

[0061]

[Table 2]

[0062]

The tubular foam according to the first aspect of the present invention has the above-described structure, and therefore has excellent insertability to the outer peripheral surface of the pipe and dimensional stability after the application. ing. Since the tubular foam of the present invention according to claim 2 or 3 of the present invention has the above-described configuration, it has excellent dimensional stability even at a high temperature such as at the time of a defrosting operation, and has good insertion workability. Excellent in both flexibility. The tubular foam of the present invention according to claim 4 of the present invention has the above-described configuration, and thus has excellent mechanical strength, is difficult to set, and has heat insulating properties even in a portion where a high load is applied, such as a pipe support portion. Etc. are not impaired.
In addition, since the elongation in the length direction of the tubular foam is reduced at the time of the insertion work, the insert workability is improved. Claim 5 of the present invention
Since the tubular foam described in (1) is fitted on a curved tube, excellent heat insulating properties can be imparted even to a curved portion where a heat insulating material has conventionally been difficult to be fitted.

Continuation of the front page F term (reference) 3H036 AA01 AA05 AB18 AB25 AC01 AD01 AE13 3L051 BF03

Claims (5)

[Claims] 1. A tubular foam comprising a crosslinked foam mainly composed of a propylene-based thermoplastic elastomer. 2. A propylene-based thermoplastic elastomer,
When the temperature rise elution fractionation was performed by the cross fractionation method,
The resin elution amount at 30 ° C. or more and 10 ° C. or less is 30 to 70% by weight of the total amount of the propylene-based thermoplastic elastomer, and 10 ° C.
The resin elution amount at a temperature exceeding 60 ° C. and not more than 60 ° C. is 0 to 30% by weight based on the total amount of the propylene-based thermoplastic elastomer, and the resin elution amount at a temperature exceeding 60 ° C. and 130 ° C. or less is 15 to 30% by weight of the total propylene-based thermoplastic elastomer. The cylindrical foam according to claim 1, wherein the weight is 65% by weight and the weight average molecular weight is 80,000 to 500,000. 3. The heating dimensional change rate is 5% or less, and the Young's modulus in the length direction and the radial direction is 0.5 to 12.0 kgf / c.
The tubular foam according to claim 1 or 2, wherein m is m. 4. The cross-linked olefin resin foam is coated on the outer peripheral surface thereof.
The tubular foam according to any one of the above. 5. The tubular foam according to claim 1, wherein the tubular foam is fitted on a rigid curved tube.