JPS6082320A - Meshy fiber sheet for heat insulating material - Google Patents

Abstract

PURPOSE:To render a meshy fiber sheet for heat insulating material soft with a higher productivity and higher durability by using a meshy fiber sheet as intact or laminated in more than one layers after obained by extrusion of a specified metal fine powder and thermoplastic resin being melted with a slit die. CONSTITUTION:A metal fine powder selected from the group of aluminum, copper, nickel, brass and iron and a thermoplastic resin containing foaming material are extruded as melted from a slit die to make a meshy fiber sheet. The meshy fiber sheet has such characteristics as average distance (l) between connection points of 1-50mm., vertical tensile strength (m) more than 0.05g/de and average diameter (d) of fiber 1-100mum. This can be extended and expanded easily with a large multiplying factor and moreover, an even meshy fiber sheet can be formed by extension and expansion. The meshy fiber sheet thus obtained is used as intact or laminated in more than one layer and extended and expanded more than twice laterally and with a multiplying factor A to meet 1m.l<=A<=5m.l to obtain a meshy fiber sheet for heat insulating material.

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a reticulated fiber sheet for heat insulating material. Specifically, the present invention relates to a reticulated m-fiber sheet for heat insulating material containing fine metal powder and air bubbles. The reticulated fiber sheet for heat insulating materials of the present invention can be used in various fields such as sports clothing, casual clothing, and bedding. The reticulated fiber sheet for heat insulating materials of the present invention has a high heat insulating effect even when it is extremely thin, so it is particularly suitable for fields such as sports clothing, clothing for infants, kotatsu blankets, and bedding. BACKGROUND OF THE INVENTION Various methods have been attempted in the past to improve the heat retention effect of metal bedding materials, vehicle interior materials, etc., but most of them have mainly utilized metal vapor deposition technology. For example, a metallized nonwoven fabric is made by stacking a thin web layer with a sheet whose surface is metallized and then needle-punching both to make some of the fibers that make up the thin web layer protrude onto the surface of the metallized sheet, thereby integrating the two. "A kotatsu futon" (Fukosho No. 58-10916) is made by stacking a cotton layer with a cotton layer so that the metal-deposited surface is the outer surface, and covering both with a side cloth. Alternatively, in order to solve the drawbacks of metal vapor-deposited nonwoven fabrics, such as the tendency of the vapor-deposited metal to peel off, [after vacuum-depositing aluminum on polyester fiber fabric, isophthalic acid or its derivatives, neobenthyl glycol, polyalkylene glycol, etc. Softening point: 60
A method for producing an aluminum vapor-deposited polyester fabric with excellent durability, characterized in that a composition having a temperature of 0.3% by weight or more and less than 3% by weight is deposited on the fabric at a temperature of 0.3% by weight or more and less than 3% by weight J</If- Publication No. 58-136891) is disclosed. All of these techniques use metal evaporated bodies and are aimed at preventing heat from escaping to the outside as much as possible or cutting off heat from the outside. OBJECTS OF THE INVENTION However, the above-mentioned conventional buttons using metal vapor deposition technology have the following drawbacks. (1) Since the metal vapor deposition process involves depositing gold < M in the air to a thickness greater than λ that reflects hot rays, the manufacturing process must be discontinuous and require long-term pressure, so the degree of continuity is low. Therefore, it is difficult to increase productivity. (2) Metal evaporation is simply a matter of depositing metal onto a target object, so for example,
Even if the device is constructed as described in the 916 publication, it may suffer from abrasion due to rubbing, repeated washing, or massaging at °C.
It is inevitable that the metal deposited during the first step will gradually peel off. In other words, it has the disadvantage of low durability. (3) The surface of the vapor-deposited metal is coated with a resin as in the invention described in JP-A-58-136891 mentioned above.
When durability is increased, the layer composed of vapor-deposited metal and surface coating resin has the drawback of giving the heat insulating material a stiff feeling and impairing its flexibility. The inventors of the present invention have conducted studies to solve these drawbacks of heat insulating materials in the prior art, and as a result, have arrived at the present invention. A reticulated fiber sheet obtained by extruding a thermoplastic resin containing one or more fine metal powders selected from the group consisting of copper and iron and a foamable substance in a molten state through a slit die, The average distance between bonding points is 1 to 5° Inff+, the tensile strength in the longitudinal direction is 0.05, lit/de
As described above, the following formula (1) is obtained by laminating two or more reticular fiber sheets with an average fiber weight of 1 to 1100p as is or by laminating two or more sheets.
A reticulated fiber sheet for heat insulating material obtained by spreading in the horizontal direction at a magnification (5) that satisfies (2) and Tensile strength in the direction (Ji'
/de). If ω and m is greater than or equal to IJ7/de, m = 1. l represents the average distance between bonding points of the reticular fiber sheet. ) (2) A reticulated fiber sheet for heat insulating material according to claim (1), in which the fine metal powder is in the form of flakes (3) The longest diameter of the fine metal powder is 10071 m
A reticulated fiber sheet for heat insulating material according to claim (1) or (2). The metal used in the present invention is aluminum. One or more types selected from the group consisting of copper, nickel, brass, and iron. All of these metals have extremely low heat ray radiation, and when used as heat insulators, they can have a high heat retention effect.These metals can be used alone, but two or more types can be used together. Even if they are used in combination, the same heat retention effect can be obtained. Aluminum is particularly preferred in terms of availability, ease of handling, quantity, etc. The shape of the metal may be in the form of a fine powder, but preferably a non-spherical shape. Non-spherical shapes include linear, rod-like, flaky, etc. Thin flakes, long flakes, #4 flakes, and cloud-shaped ones are rated 4 in terms of heat shielding effect (heat retention effect). preferred. The average particle size of the fine metal powder is preferably 80/7 m or less, and if it is a normal fiber, the M fiber diameter of the stretched edge is approximately 10 to 5071
m, the average particle diameter of the Kinzo fine powder contained in the fiber is limited to 40 μm or less, preferably 201 trn or less, but unlike ordinary fibers, the reticular fiber sheet produced by Kinei Meijyo has an average fiber diameter of 1 to 10011 m. Since it is a reticulated fiber sheet, even an average particle size of 80 μn1 can be contained in the reticulated fiber sheet. The content ratio of the fine metal powder to the weight of the reticular fiber sheet IJIK is preferably 1 to 60% by weight. Especially 5 to 40 weight il
A range of l is more preferred. If the weight ratio is less than 1 weight, the heat retention property is insufficient. If it exceeds 30% by weight, the moldability of the reticulated fiber sheet may deteriorate.

[・The physical properties of the sticky reticular fiber sheet lose its practicality. The fine metal powder contained in the fibers is preferably arranged in parallel to the extrusion direction (discharge direction) K of the reticular fiber sheet. For example, when a thermoplastic material containing a scaly metal powder and a foamable substance is extruded through a cylindrical slit, the scaly metal fine powder is preferably arranged in parallel to the extrusion direction within the cylindrical slit. Such a structure can be formed by extruding the thermoplastic material using a slit die having a core-sheath structure. With such a two-layer structure, the amount of metal fine powder used can be reduced.
Since the physical properties of the reticulated fiber sheet are maintained by the inner layer (core) that does not contain fine metal powder, the performance deterioration of the reticulated fiber sheet due to the inclusion of fine metal powder, such as strength deterioration and elongation deterioration, is only slightly reduced. can be kept at Of course, even if the entire cross section of the reticulated fiber sheet contains gold FA fine powder, the heat retention effect can be achieved, but the reticulated M1. Maintains the performance of fiber sheets. A two-layer structure is preferable from the viewpoint of high heat retention effect. The reticulated fiber sheet in the present invention is produced by extruding a thermoplastic resin together with a fine metal powder and a foamable material in a molten state through a slit die.
It is obtained by winding at twice the draft rate, and has the characteristics described below. The thermoplastic resin that makes up this reticulated fiber sheet is
Its melting point is 70-3 Fi O'C1 especially 90-300
Preferably, the temperature is within the range of °C. Such thermoplastic resins include, for example, diethylene, propylene, styrene, acrylic ester, vinyl acetate,
Homopolymers or copolymers of two or more of starting materials such as acrylonitrile and vinyl chloride (11) For example, phthalic acids (phthalic acid, in-7thalic acid, terephthalic acid, and their nuclear alkyl substituted products), naphthalene dicarboxylic acid Aromatic dicarboxylic acids having 8 to 15 carbon atoms such as, 6 to 3 carbon atoms
At least one dicarboxylic acid component selected from the group consisting of aliphatic dicarboxylic acids and alicyclic dicarboxylic acids (
or its lower alkyl ester) and a carbon number of 2 to 1
Polyester or charcoal formed from at least one glyfur component selected from the group consisting of aliphatic glyfur or alicyclic glycol of 2 and an aromatic dihydroxy compound having 6 to 15 carbon atoms! l! A polyester formed from two human mixed carboxylic acids (or lower alkyl esters thereof), or a mutual copolymer polyester thereof (for example, an aliphatic dicarboxylic acid having 4 to 12 carbon atoms and an aliphatic dicarboxylic acid having 4 to 12 carbon atoms) Polyamide or amino acid formed from J5 aliphatic or aromatic diamine (
Examples include polyamides formed from [7-lactams] or their mutual copolymers, Oψ such as bisphenol-based polycarbonates, (Vl polyacetals, etc.), and various polyurethanes. A reticulated fiber sheet is obtained by extruding the powder and a foamable substance in a molten state through a slit die.The foamable substance is a substance that becomes a gas when the molten resin is extruded from the slit die. It may itself have the property of generating such a gas, or it may contain a substance that generates a gas. For example, (Al nitrogen) is liquid at room temperature, but at the melting temperature of thermoplastic resin. A method of kneading a gaseous substance with a molten thermoplastic resin, (C) for example, a diazo compound,
(d) A method of kneading a substance that generates a gas by decomposition, such as soda carbonate, with a molten thermoplastic resin; There are methods such as mixing the coalesce with such molten thermoplastic resin. In either method, when the thermoplastic resin is extruded in a molten state through a slit die, it is sufficient that a gas co-occurring with the resin is generated from the die, but the various foamable substances and metal fine powders mentioned above can be produced. It is preferable that only the thermoplastic resin be sufficiently kneaded with the thermoplastic resin. If this crosstalk is not sufficient, it will be difficult to obtain a reticulated fiber sheet that is uniform and has desired physical properties. An example of a method for obtaining a reticulated fiber sheet by melting and extruding a thermoplastic resin together with a fine metal powder and a foamable substance through a slit die in a molten state will be described below. Vent a thermoplastic resin containing fine metal powder in the middle
It is extruded from a heating extruder with In this way (-[The discharged resin contains an inert gas as small bubbles.The molten thermoplastic resin containing the gas is discharged under pressure through a slit die.The slit interval of this slit die is , preferably about 20 μ to 1 mm, and 50 μ to 1 mm.
μ to 500 μ is more preferable. The pressure at this time is 9 in 10
/cIIG or more preferably 3okg/cr! G or higher is appropriate. If it is less than 10 kg/iG, a sheet with a uniform mesh cannot be obtained, or in extreme cases, a foamed film-like sheet may be obtained. As mentioned above, it is necessary to quickly cool the resin discharged from the die. This cooling is a factor that determines the size of the mesh, so it is desirable to manage it adequately. For example, if it is desired to produce a reticulated fiber sheet with a large mesh, it is sufficient to reduce the amount of cooling, and if the mesh is to be made thin, the opposite is true. For this cooling, air cooling method is preferable.
The mesh can be adjusted by changing the air volume. However, it is also possible to use liquids, such as water, or contact with cooled solids. The thus discharged resin needs to be taken up at a sufficient speed. If this take-up speed is not sufficient, the obtained reticular fiber sorting may be weak, or in extreme cases, the film may have holes. The guideline for this take-up speed is expressed as a draft rate, and the take-up is usually done at a draft rate of 10 to 300 times, preferably 20 to 200 times. Here, the draft rate is expressed as the ratio of the drawing speed to the linear speed of the resin passing through the die. If spreading is performed during pick-up, it is natural to convert the speed to the speed when spreading is not performed. Furthermore, one method for adjusting the mesh size of the reticulated fiber sheet is to change the melt viscosity of the resin. Methods for changing the melt viscosity include, for example, changing the temperature conditions, changing the degree of polymerization of the resin, using plasticizers, etc., or using a combination of these methods, but the most effective method is to change the temperature conditions. easy and preferred). An example of the method for producing a reticulated fiber sheet has been described above [5] However, the reticulated fiber sheet of the present invention is in no way limited to that obtained by the Queen's method. In addition, for example, a thermoplastic resin containing fine metal powder is melted together with a gas-generating substance by thermal decomposition and extruded through a slit die; There is a method in which resin is kneaded with an inert gas and then extruded through a slit die. In these methods as well, it is preferable that the cooling and take-up be performed in the same manner as described above and in Jff1. The reticulated fiber sheet in the present invention is obtained by the method described above, and (1) has an average distance between bonding points of 1 to 50 ml11 (2)
It has the following characteristics: a tensile strength in the longitudinal direction of 0.05 g/de or more, and (3) an average fiber diameter of 1 to 100 μm. A reticular fiber sheet that satisfies all of the requirements (+), (2), and (3) above can be easily stretched at a large magnification, and can also be stretched to form a uniform reticular fiber sheet. . In the present invention, the above-mentioned "average distance between bonding points,""tensile strength in the girder direction," and "average diameter of fibers" are each measured by the following methods. (1) Average distance between bonding points (71 Spread one reticular fiber sheet twice in the horizontal direction by 1 c and 10 c
111, and calculate the total denier (de) of the reticular fiber sheet by measuring the distance between all the bonding points included in Cut the hook in the vertical direction to 10,000 deK, give one twist per 1α of length, and pull at a distance between chucks of 50 and a pulling speed of 56 m/min.The value is the maximum tensile stress divided by the denier (de). .When laminating two or more sheets, cut the object vertically and measure in the same way.Dan = U!'' YoJ LiaoL Use a 400x magnification mirror to draw a straight straight line in the direction perpendicular to the fibers. Then, measure the fiber diameter of the fibers on the W line in order at VC10 to 25 points, cross the samples, repeat this method, measure a total of 100 points, and take the average value of all of them. For the reticulated #fiber sheet, the requirements of (11, f21 and (3)) are determined according to each measurement described above. If the average distance between bonding points is shorter than I Fm, the number of bonding points becomes too large and It is not possible to obtain a stretching magnification, and a uniform reticular fiber sheet cannot be obtained.On the other hand, if the average distance between bonding points exceeds 50 mm, it becomes extremely difficult to form a uniform sheet in the same manner as when it is stretched.Especially The distance between bonding points is preferably in the range of 2 to 40. On the other hand, the reticulated fiber sheet has a tensile strength in the longitudinal direction of O
-05Ji'/de or more, preferably o,t g/de
That's all. If the tensile strength in the longitudinal direction is smaller than the above range, not only will it be substantially difficult to spread, but it will also be difficult to obtain a reticulated fiber sheet with practically sufficient strength. As mentioned above, even if (1) the distance between bonding points and (2) the tensile strength in the longitudinal direction satisfy the above ranges (unless it is a reticular fiber sheet whose average diameter of 31 m fibers satisfies the range of 1 to Zooμ), It is not possible to obtain the desired reticular fiber sheet.It is difficult to obtain a reticular fiber sheet with stable strength when the average fiber diameter is smaller than 1β.On the other hand, when the average fiber diameter is larger than 100μ, it is difficult to obtain a reticular fiber sheet with stable strength. It is not possible to obtain a uniform reticulated fiber sheet with good properties.The reticulated fiber sheet of the present invention is made by using reticular fiber sheets that satisfy the requirements of (11, (21) and (3) above, either as they are or by laminating two or more sheets). It can be obtained by expanding in the horizontal direction to a magnification (Δ) that is twice or more and satisfies the following formula +11. If the spreading magnification of 7.1 in this direction is smaller or larger than the above range, a uniform reticular fR
You can't get a seat. The stretching of the reticulated fiber sheet in the present invention involves expanding the mesh in the horizontal direction, and the methods include (for example, the method of spreading a reticulated fiber sheet in the horizontal direction while gripping both ends of the reticulated fiber sheet, and the circular There is a method in which a mesh or fiber sheet extruded from a shaped slit is undulated in the diametrical direction of the slit.In particular, a method in which a large number of sheets are laminated (7) and spread horizontally while grasping both ends is preferred.Next A method of applying pressure waves in the horizontal direction while gripping both ends will be explained below, but the same applies to a method of rolling it in the diametrical direction. It is preferable to over-eed the fibers by twice as much. This overfeed determines the orientation angle of the fibers, and as the amount of overfeed increases, the sheet becomes horizontally oriented. Also, the optimal spreading magnification changes depending on the overfeed ratio. , when overfeeding about 3 times,
According to the above definition, the spreading magnification is 3~s m- times, and on the other hand, if the overfeed rate is about 1.3 times, 1 m
-1x spreading magnification is good. This overfeed rate can be determined consciously, which is preferable.
Sometimes it happens naturally. For example, when a finite length reticular fiber sheet is expanded in the horizontal direction, the length in the vertical direction becomes shorter. It is appropriate to carry out the spreading method in consideration of such overfeeding. For example, when holding both ends with a pin tenter, the reticular fiber sheet is fed and woven with a feed roller having a peripheral speed faster than the speed of the pin tenter. There is a way to stick it in a bottle while it is folded. It is necessary to spread the reticulated fiber sheet that has been overfed in this way in the horizontal direction. The method of expanding in the horizontal direction is to grip only both ends and expand as described above, to expand each zone in several zones in the width direction, or any other method. Any means that can spread it evenly will suffice. As mentioned above, the stretching may be carried out with the reticular fiber sheet as it is or with two or more sheets laminated. When two or more sheets are laminated, the number is 2 to 2000, preferably 10 to 1.
A range of 000 sheets is desirable. The reticulated fiber sheet thus spread becomes a uniform reticulated fiber sheet. This reticulated fiber sheet is useful as a nonwoven fabric as it is or by methods such as needle punching, stitch pounding, and quilting. Effects of the Invention As a result of configuring the present invention as described in detail above, the present invention has the following effects. (1) Unlike conventional metal vapor-deposited sheets, the reticulated fiber sheet for heat insulating materials of the present invention can be continuously produced because metal is contained within the reticulated fiber sheet itself. (2) Unlike conventional metal vapor-deposited sheets, the reticulated fiber sheet itself contains metal, so the heat retention effect is permanently constant and there are no durability problems such as washing resistance. (3) Unlike conventional metal vapor-deposited sheets, vapor-deposited gold J
There are no problems such as the stiffness of the sheet due to qK or the loss of flexibility of the sheet. (4) The sheet can be made thinner because the fiber containing fine metal powder has a high heat retention effect. Therefore, it has practical heat retention properties without being molded into a laminate like conventional products. The present invention will be specifically explained below in Examples, but the present invention is not limited to the following implementation side pressures. Note that "parts" in the examples refer to parts by weight. Example 1 (5) Average particle size] Polypropylene 100% talc 1 containing 10 wt% of 0.2 μm flaky aluminum powder
Continuously feed the part into an extruder with a gas inlet with an inner diameter of 30mm, and while pushing nitrogen gas through the gas inlet at a pressure of sokg/7G, extrude the extruder with a diameter of 140mm with an interval of 250μm.
It was extruded through a circular slit die. At this time, the temperature is 240℃ near the feed part of the cylinder, 300℃ at the cylinder tip, and 280℃ at the die, and the discharge rate is 45I/min. regulated by a gear pump. The polymer discharged from the die was immediately cooled by cooling air at 25° C. and taken off at a taking-off speed of 80 m/min to obtain a reticulated fiber sheet. This reticulated fiber sheet was obtained from a similar device.
They were stacked one on top of the other and wound up on a bobbin as a laminate. Winding was performed by crushing the obtained cylindrical sheet into a flat shape with a width of 20 m, and one laminate that was wound up was composed of 8 reticulated fiber sheets. The total strength of the fiber sheet was 20,000 de, and the strength was 3.1 y. Based on this, the tensile strength was O-151/de. The average diameter of the fibers was 36 μm as measured using a microscope. The average distance between the nodal points was 16.5 mm when one reticulated fiber sheet was peeled off and expanded horizontally to twice the size of C.The value obtained by multiplying this tensile strength by the average distance between the nodal points was 16.5 mm. is 2.5. (Bl 84 pieces of the orange waste of the reticulated fiber sheet obtained in (5) above were spread using a 1I pin tenter. Two pairs of rows of bottles were arranged at 160 mm in the inlet of the pin tenter.
It was constructed so that it was spread out at an angle of 5°, and the pin was spread out at a width of 1280 mm and then cut (spreading magnification: 8 times). The inlet of this pin tenter is 1.8 times the moving speed of the pin (overfeed rate 1.
The reticulated fiber sheet of (2) was fed at a speed of 7 times) and spread by inserting both ends into a bottle. It was cut at a pin width of 1280 mrn to obtain a reticulated m-fiber sheet. (q The reticular fiber sheet obtained in the above (Bl) was heated to 160°C
Treatment in a hot air dryer for 30 seconds [1. A bulky nonwoven fabric was obtained. The physical properties are shown in Table-1. The obtained reticulated 11i fiber sheet has few spots and is uniform.
Moreover, the heat retention property was extremely good, the drapability and washing resistance were also good, and the general physical properties were of practical use. Examples 2 to 7 Various metal fine powders (aluminum, copper, nickel, brass,
A reticulated fiber sheet was prepared in the same manner as in Example 1 (3) using iron) alone or in combination. Also, the number 1 of Example 1. (Table 1 shows the physical properties of the reticulated fiber sheet obtained by spreading the sheet in the same manner as in Example 1 while changing the spreading ratio.)
2.3.4 Not containing fine metal powder The sheet prepared using the same treatment method as in Example 1 had low heat retention. In addition, the reticulated fiber sheet produced in the same manner as in Example 1 except that polypropylene containing 10 wt % of chromium-nickel alloy fine powder with an average particle size of 10.28 m as the metal fine powder was used, and the heat retention was low. Next, the reticular fiber sheet obtained in (4) of Example 1 (B
It was spread using a pin tenter similar to 1. At this time, the cutting place is set at the point where the width of the bottle is 320 mm (spreading magnification: 2x) r-
The procedure was the same as in Example 1 except that the steps were carried out. The obtained reticular rJ/1. The fiber sheet is as shown in Table-1.
There was a lot of unevenness. Similarly, if we set the point where the pin width is 2080 mm (spreading magnification: 13x) at the point where the pin is to be cut, it was confirmed that there would be some cracks in some parts before reaching the cutting point, and the result would be clearly uneven. Ta. Comparative Example 5 A reticulated fiber sheet was obtained in the same manner as in Example ICA1, but with a slit interval of 1ffIff+ and drawing from the die at a drawing speed of 411 rn/min. This cotton fiber sheet has an average diameter of 15
(lμ, distance between nodes 12.2 mm, tensile strength 0
．． It was 11/de. The obtained reticulated fiber sheet had a marked thickness unevenness in appearance and was unsuitable for use as a heat insulating material. As a result, reticular fiber sheets with varying distances between bonding points and tensile strength were obtained.The results of measuring the physical properties of the obtained reticulated fiber sheets and the state when stretched are shown in Table 2.Distance between bonding points If the tensile strength is too short, it will not be possible to form a uniform reticulated fiber sheet even if it is spread, and if the tensile strength is weak, the reticulated fiber sheet may be cut or uneven during stretching, making it impossible to obtain a uniform reticulated fiber sheet. Examples 8 to 11 One piece of aluminum scale-like fine powder with an average particle size of 10.2 μm was
Using various polymers containing 0 wt% or aswt%, a reticulated fiber sheet was created by changing the melting temperature, gas inlet temperature, die temperature, discharge amount, take-up speed, cooling rate, etc.
Ta. Table 1 shows the properties of the reticular fiber sheet obtained by spreading in the same manner as Q31° (C1) in Example 1.The obtained cotton fiber sheet had good heat retention and drapability. The washing resistance was also good, and the physical properties were within a practical range.The results are shown in Table 2. Comparative Example 8 Aluminum scrap square foil (maximum diameter 1 mm)
An attempt was made to obtain a reticulated ##A sheet in the same manner as in Example 1 using polypropylene containing 9 wt. I couldn't get it. Comparative Examples 9 and 10 Non-spherical aluminum fine powder 0.5wt% or 6
An experiment was conducted to obtain a reticulated fiber sheet in the same manner as in Example 1 using polypropylene containing 3 wt%. The results are shown in Table 2. o, swt%, high heat retention properties could not be obtained, and although various conditions were investigated for sawtqb, it was not possible to obtain a reticulated fiber sheet.

Claims (1)

[Claims] A thermoplastic resin containing one or more fine metal powders selected from the group consisting of (11) aluminum, copper, nickel, brass, and a foamable substance is melted through a slit die. A reticular fiber sheet obtained by extrusion, wherein the average distance between bonding points on the sheet is 1 to 50 mm,
Reticular fiber sheets having a tensile strength in the longitudinal direction of n, o s g/de or more and an average fiber diameter of 1 to 100 μm are used as they are or two or more sheets are laminated to form the following formulas (1) and (2).
) is the tensile strength of the reticulated fiber sheet in the vertical direction. Strength (#/c
te). However, when m is 1 l / d6 or more, m = 1. l indicates the average distance (distance) between bonding points of the reticular fiber sheet. ) (2) Claim No. 2 in which the fine metal powder is in the form of flakes (
Claim (1) wherein the longest diameter of the reticulated fiber sheet for heat insulating material (3) metal fine powder is 600 pm as described in item (1)
) or (21) reticulated fiber sheet for heat insulating material