JP2002249973A - Net-like fiber sheet for heat-insulation material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a net-like fiber sheet obtained by allowing a carbon fine powder to be included in the fiber itself of the net-like fiber sheet, and as a result, to provide various kinds of products having excellent flexibility and heat-insulation effects, and capable of exhibiting excellent durability and deodorant effects. SOLUTION: This net-like fiber sheet is produced by extruding a thermoplastic resin containing one or more kinds of the carbon fine powders selected from Bincho-tan (a kind of charcoal), bamboo charcoal, an activated charcoal and a carbon black, and a foaming material, in a molten state from a slit to provide the net-like fiber sheet having 1-50 mm average distance between nodes, >=0.0005 N/dtex tensile strength in the machine direction, and 1-150 μm average diameter of the fiber in the net-like fiber sheet, and extending one, or two or more of the sheets in the transverse direction at a specific magnification.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a mesh fiber sheet for a heat insulating material. More specifically, the present invention relates to a net fiber sheet for a heat insulating material containing fine carbon powder and bubbles. The mesh fiber sheet for a heat insulating material of the present invention can be used in various fields such as sports clothing, casual clothing, inner clothing, and bedding products. The reticulated fiber sheet for heat insulating material of the present invention has a high heat insulating effect even in extremely thin ground, and is particularly suitable for the fields of sports clothing, baby clothing, kotatsu quilts, bedding, underwear and the like.

[0002]

2. Description of the Related Art Various attempts have been made to utilize carbon powder for improving the heat retaining effect of bedding materials, interior materials, etc., but there is a method mainly using a technique of fixing carbon powder with a binder. Many. For example, "a fine powder of charcoal or charcoal in an amount of 10 to 60 g / ^{m 2,} 2m in the void ratio of 50% or more
a nonwoven fabric mat material which is bonded to the entire surface and inside of a nonwoven fabric made of a synthetic fiber having a thickness of m or more via a water-soluble adhesive so as to have a high density at the entangled portion of the fiber " 2000-027071).
Alternatively, there is disclosed "a white charcoal sheet material which is formed into a sheet by compressing a fine particle of white charcoal into a nonwoven fabric core material via a special binder" (JP-A-11-290683). All of these techniques are intended to provide a nonwoven mat material or sheet material excellent in deodorization and humidity control by using carbon powder.

[0003]

However, the above-mentioned prior art utilizing the fixation of carbon powder with a binder has the following disadvantages. (A) In the fixing treatment of carbon powder with a binder, for example, an emulsion of carbon powder and an acrylate ester is uniformly kneaded during the processing step, uniformly applied and adhered on a sheet, and the binder is cured by heat treatment. Therefore, the process must be discontinuous and long, and it is difficult to increase the productivity. (A) Since the carbon powder is fixed to the sheet only by adhering the carbon powder on the sheet or between the sheets, it may be repeatedly rubbed, worn or repeatedly washed.
It is unavoidable that the adhered carbon powder gradually peels off and falls, and a reduction in durability cannot be denied. (C) In the case where the surface of the carbon powder is coated with a resin to increase the durability, the layer having such a configuration gives a stiff feeling to the product and impairs flexibility.

[0004]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the reticulated fiber sheet for a heat insulating material according to the present invention comprises a thermoplastic resin containing at least one carbon fine powder selected from the group consisting of Bincho charcoal, bamboo charcoal, activated carbon and carbon black, and a foamable substance. A reticulated fiber sheet obtained by extrusion in a molten state, wherein the average distance between bonding points in the sheet is 1 to 50 mm, the tensile strength in the vertical direction is 0.0005 N / dtex or more, and the average fiber diameter is 1
It is obtained by extending a reticulated fiber sheet having a thickness of about 150 μm or two or more sheets and extending in the horizontal direction at a magnification A satisfying the following formulas (1) and (2). 100m · L ≦ A ≦ 500m · L (1) 2 ≦ A (2) (m is the tensile strength of the reticulated fiber sheet in the vertical direction (N / d
tex). However, when m is 0.01 N / dtex or more, m is set to 0.01. L indicates the average distance (mm) between the bonding points of the reticulated fiber sheet. At this time, the longest diameter of the carbon fine powder is 500 μm, and the content of the carbon fine powder is 2 to 14% by weight.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The carbon fine powder used in the present invention is at least one selected from the group consisting of Bincho charcoal, bamboo charcoal, activated carbon, and carbon black. Each of these is a carbon group having a very low radiant power of heat rays, and when used for a heat insulating material, can provide a high heat insulating effect.The carbon fine powder may be used alone, but two or more kinds thereof may be used. Even when mixed and used, a heat retaining effect can be obtained similarly.

The average particle size of the carbon fine powder is 120 μm.
The following are preferred. In the case of conventional fibers, since the fiber diameter after drawing is about 10 to 50 μm, the average particle diameter of the metal fine powder generally contained in the fiber is 40 μm.
μm or less, preferably 20 μm or less, the average fiber diameter of the reticulated fiber sheet of the present invention is 1 to 150 μm.
Since the reticulated fiber sheet has an average particle size of m, even a reticulated fiber sheet having an average particle size of 120 μm can be included in the reticulated fiber sheet.

In this case, the content of the fine carbon powder with respect to the weight of the reticulated fiber sheet is preferably in the range of 2 to 14% by weight. In particular, the range of 3 to 12% by weight is more preferable. If it is less than 2% by weight, the heat retention is insufficient, and if it exceeds 15% by weight, the moldability of the reticulated fiber sheet deteriorates, and the physical properties of the reticulated fiber sheet lose practicality.

[0008] The state of the carbon fine powder contained in the fiber is preferably arranged in parallel with the extrusion direction (discharge direction) of the reticulated fiber sheet. For example, when a thermoplastic substance containing carbon fine powder and a foamable substance is extruded from a cylindrical slit, it is preferable that the carbon fine powder be arranged in the cylindrical slit in parallel with the extrusion direction. Such a structure can be formed by extruding the thermoplastic material using a slit die having a core or structure. With such a two-layer structure, the amount of carbon fine powder used can be reduced,
Since the physical properties of the reticulated fiber sheet are maintained by the inner layer portion (core portion) that does not contain the fine carbon powder, the performance of the reticulated fiber sheet due to the inclusion of the fine carbon powder, for example, the strength deterioration, the elongation deterioration, and the like are slightly reduced. Can be stopped.

The reticulated fiber sheet of the present invention is obtained by extruding a thermoplastic resin together with a fine carbon powder and a foamable material in a molten state from a slit die at a draft rate of 10 to 300 times, preferably 20 to 200 times. It has the characteristics described below.

[0010] The thermoplastic resin constituting such a network fiber sheet has a melting point of 70 to 350 ° C, particularly 90 to 300 ° C.
Those in the range of ° C are preferred. Such thermoplastic resins include, for example, (A) ethylene, propylene, styrene,
Acrylic acid ester, vinyl acetate, acrylonitrile,
Homopolymers or two or more copolymers starting from vinyl chloride or the like; (i) for example, phthalic acids (phthalic acid, isophthalic acid, terephthalic acid, their alkyl substituted nuclei), naphthalene dicarboxylic acid, etc. 8 to 1 carbon atoms
At least one dicarboxylic acid component (or a lower alkyl ester thereof) selected from the group consisting of aromatic dicarboxylic acids having 5 carbon atoms, aliphatic dicarboxylic acids having 6 to 30 carbon atoms, and cyclic dicarboxylic acids; A polyester formed from an aliphatic glycol or an alicyclic glycol and at least one glycol component selected from the group consisting of aromatic dihydroxy compounds having 6 to 15 carbon atoms, or a hydroxycarboxylic acid having 4 to 12 carbon atoms ( Or a lower alkyl ester thereof), or a mutual copolymerized polyester thereof, for example, from (a) an aliphatic dicarboxylic acid having 4 to 12 carbon atoms and an aliphatic or aromatic diamine having 4 to 15 carbon atoms. Formed from polyamides or amino acids (or lactams) Polyamide or cross-copolymers thereof, (e) For example, bisphenol-based polycarbonate, (E) polyacetal, and (or) various polyurethanes and the like.

As described above, the thermoplastic resin is extruded together with the carbon fine powder and the foamable substance in a molten state from a slit die to obtain a reticulated fiber sheet. When the foamed substance and the molten resin are extruded from the slit die,
It is a substance that becomes a gas, and the resin itself may have a property of generating such a gas, or may contain a substance that generates a gas. For example, (g) a method of kneading a gaseous substance at room temperature, such as nitrogen gas or carbon dioxide gas, into a molten thermoplastic resin, or (g) a liquid at room temperature, such as water, but a gas at the melting temperature of the thermoplastic resin. A method of kneading a substance that becomes a gas with a molten thermoplastic resin, a method of kneading a substance that generates a gas by decomposition of a diazo compound, sodium carbonate, or the like with the molten thermoplastic resin, a method such as a polycarbonate, There is a method of kneading a polymer that generates a gas by reacting with a part of the molten thermoplastic resin (for example, polyester or polyamide) with such a molten thermoplastic resin.

In any of the methods, when the thermoplastic resin is extruded from the slit die in a molten state, the gas may be generated from the die together with the resin. It is preferable that the resin is kneaded with the thermoplastic resin as much as possible. If the kneading is not sufficient, it is difficult to obtain a reticulated fiber sheet having uniform and desired physical properties. An example of a method of obtaining a reticulated fiber sheet by melting and extruding a thermoplastic resin from a slit die in a molten state together with carbon fine powder and a foamable substance will be described below.

A thermoplastic resin containing fine carbon powder is extruded from a heating extruder having a vent in the middle, and an inert gas such as nitrogen is injected from the middle vent. The resin discharged in this manner contains an inert gas as small bubbles. The molten thermoplastic resin is discharged through a slit die in a pressurized state. At this time, the slit interval of the slit die is set to about 20 μm to 1 mm.
Those having a thickness of from 500 to 500 μm are more preferred. The pressure is 1.
0 Pa / cm ² G or more, preferably 3.0 Pa / cm ² G
The above is appropriate. If less than 1.0 Pa / cm ² G,
A uniform mesh sheet cannot be obtained, or in an extreme case, a sheet like a foamed film can be obtained.

As described above, it is necessary to rapidly cool the resin discharged from the die. This cooling is a factor that particularly determines the size of the mesh, and it is desirable that the cooling be sufficiently controlled. For example, if it is desired to produce a mesh-like fiber sheet having a large mesh, the cooling may be reduced, and if the mesh is made thin, the opposite is true. Generally, this cooling is preferably performed by air cooling, and the mesh is adjusted by changing the air flow. However, it is also possible to use a liquid such as water or to contact a cooled solid. is there.

The resin thus discharged needs to be taken up at a sufficient speed. If the take-up speed is not sufficient, the obtained reticulated fiber sheet is weak, and in extreme cases, the film is perforated. The standard of the take-off speed is expressed by a draft rate, and is usually 10 to 300 times, preferably 2 to 300 times.
Accepted at a draft rate of 0 to 200 times. Here, the draft rate is expressed as a ratio of a take-up speed to a linear speed of a resin passing through a die. If you want to extend the exhibition during collection,
It is natural to convert to the speed when no extension is performed.

Further, as one method of adjusting the size of the mesh of the mesh fiber sheet, there is a method of changing the melt viscosity of the resin. As a method of changing the melt viscosity, for example, there is a method of changing a temperature condition, a method of changing a polymerization degree of a resin, a method of using a plasticizer, or a method of a combination thereof. Simple and preferred.

Although an example of a method for producing a reticulated fiber sheet has been described above, the reticulated fiber sheet of the present invention is not limited to those obtained by the above method. In addition to this, for example, a method in which a carbon fine powder-containing thermoplastic resin is melted together with a substance generating a gas by pyrolysis and extruded from a slit die, and a carbon fine powder-containing thermoplastic resin in a molten state using a gas kneader. After kneading an inert gas, the mixture is extruded from a slit die. Also in these methods, it is desirable that the cooling and take-off operations are performed in the same manner as described above.

The reticulated fiber sheet according to the present invention is obtained by the above-mentioned method, and (a) the average distance between the bonding points is 1 to 50 mm. (B) The tensile strength in the vertical direction is 0.0005 N. / Dte
x or more, and (c) the average diameter of the fibers is 1 to 150 μm.

A reticulated fiber sheet that satisfies all of the above requirements (a), (b) and (c) can be easily extended at a large magnification, and a uniform reticulated fiber sheet can be formed by extension. . Here, the "average distance between bonding points", "vertical tensile strength" and "average fiber diameter" in the present invention are measured by the following methods, respectively.

(A) Average distance between bonding points: L One sheet of a reticulated fiber sheet is doubled in the width direction and 10 cm
The distance between all the bonding points included in No. ³ is measured and calculated according to the following equation (3).

[0021]

[Equation (3)]

(B) Tensile strength in the vertical direction: m The reticulated fiber sheet has a total denier (dtex) of about 10,000 dt.
ex, cut in the vertical direction, give one twist per 1cm length, chuck distance 5cm, pulling speed 5c
The maximum tensile stress at a rate of
The value m is divided by x). When two or more sheets are laminated, the laminate is cut in the vertical direction and the same measurement is performed.

(C) Using a microscope with an average fiber diameter of 400, a straight line was drawn in a direction perpendicular to the fiber, and the fibers on the straight line were sequentially measured for fiber diameters at 10 to 25 points. This method is repeated and the measurement is repeated for a total of 100 points, and the average value of all the points is determined.

The requirements of (a), (b) and (c) of the reticulated fiber sheet of the present invention are determined according to the above-mentioned respective measurements. If the average distance between the joining points is less than 1 mm,
Because the number of connection points becomes too large. A large stretching magnification cannot be obtained, and a uniform reticulated fiber sheet cannot be obtained. On the other hand, if the average distance between the joining points exceeds 50 mm, it is extremely difficult to form a uniform sheet when the sheet is extended. A particularly preferred average distance between bonding points is 2
It is in the range of ４０40 mm.

On the other hand, the reticulated fiber sheet has a tensile strength in the vertical direction of 0.0005 N / dtex or more, preferably 0.001 N / dtex or more. If the tensile strength in the vertical direction is smaller than the above range, not only the spreading becomes substantially difficult, but also it becomes difficult to obtain a reticulated fiber sheet having practically sufficient strength.

As described above, even if (a) the distance between the bonding points and (b) the tensile strength in the vertical direction satisfy the above-mentioned range, (c) a mesh having an average fiber diameter in the range of 1 to 150 μm. Unless the sheet is a fiber sheet, the intended net-like fiber sheet cannot be obtained. It is difficult to obtain a network fiber sheet having an average fiber diameter of less than 1 μm having a stable strength. On the other hand, if the average diameter of the fibers is larger than 150 μm, a flexible and uniform reticulated fiber sheet cannot be obtained.

The reticulated fiber sheet of the present invention is characterized in that
A net-like fiber sheet that satisfies the requirements of (b) and (c) is obtained as it is or by laminating two or more sheets and stretching to a magnification A that is twice or more in the horizontal direction and that satisfies the following formula (1). . 100m · L ≦ A ≦ 500m · L (1) (The definitions of m and L are as described above.)

If the extension ratio in the horizontal direction is smaller or larger than the above range, a uniform reticulated fiber sheet cannot be obtained in any case. The extension of the mesh fiber sheet in the present invention is to expand the mesh in the horizontal direction,
Examples of the method include a method of expanding the mesh fiber sheet in the lateral direction while gripping both ends thereof, and a method of expanding the mesh fiber sheet extruded from the circular slit in the diameter direction of the slit. In particular, a method in which a large number of sheets are stacked and spread in the lateral direction while holding both ends thereof is preferable. Next, a method of expanding in the horizontal direction while holding both ends will be described, but the same can be said for a method of extending in the diameter direction.

When the reticulated fiber sheet is stretched in the weft direction, it is preferable that overfeed is performed 1.3 to 3 times in the vertical direction. This overfeed determines the arrangement angle of the fibers, and when the amount of overfeed increases, the sheet becomes a laterally oriented sheet. The optimum spreading magnification changes depending on the ratio of the overfeed, and when the overfeed is about 3 times, the spreading magnification is 3 to 5 m · L according to the above definition. On the other hand, if the overfeed rate is about 1.3, 100 m・ L magnification is good. The ratio of this overfeed can be determined consciously and is preferable, but in some cases, it may be made naturally. For example, when a finite-length net-like fiber sheet is expanded in the horizontal direction, this case corresponds to a case where the length in the vertical direction becomes short.

It is appropriate to carry out the spreading method in consideration of such overfeed. For example, when both ends are gripped by a pin tenter, the reticulated fiber sheet is fed by a feed roller having a peripheral speed higher than the speed of the pin tenter. Then, there is a method of pushing the pin in the folded state. It is necessary to spread the over-fed net-like fiber sheet in the horizontal direction. The method of expanding in the horizontal direction is, as described above, a method in which only both ends are gripped and expanded, a method in which the zone is divided into several zones in the width direction, and each zone is expanded. Any means can be used as long as it can be uniformly spread so as to achieve the magnification.

The above-mentioned spreading may be carried out by using a net-like fiber sheet as it is, or by laminating two or more sheets. When two or more sheets are laminated, the number is preferably in the range of 2 to 2,000, and more preferably in the range of 10 to 1,000.

The extended reticulated fiber sheet becomes a uniform reticulated fiber sheet. This reticulated fiber sheet is useful as a nonwoven fabric as it is or by a method such as needle punching, stitch bonding, or quilting.

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the following Examples. In the examples, "parts" means parts by weight.

Example 1 (A) 100 parts of polybutylene terephthalate containing 3 wt% of Bincho charcoal fine powder having an average particle diameter of 3 μm, and 1 part of talc were continuously fed to an extruder having a gas inlet having an inner diameter of 30 mm.
A 140 m diameter having an interval of 250 μm while pushing nitrogen gas at a pressure of 5.0 Pa / cm ² G from a gas inlet.
extruded from a circular slit die of m. The temperature at this time is
The feed rate of the cylinder is 240 ° C and the tip of the cylinder is 200 ° C and the die is 280 ° C from the vicinity of the gas inlet. The discharge rate is 45g / min. did. The polymer discharged from the die was immediately cooled by cooling air at 25 ° C., and was taken out at a take-up speed of 80 m / min to obtain a reticulated fiber sheet. The reticulated fiber sheet was wound on a bobbin as a laminate by superposing four weights obtained from the same apparatus. Winding is performed by crushing a sheet obtained in a cylindrical shape into a plane having a width of 20 cm, and one wound laminate is made of eight net-like fiber sheets. The obtained reticulated fiber sheet had a total of 20,000 dtex and a strength of 9.0 N. Converted from these, the tensile strength is 0.0045 N / dtex. The average diameter of the fibers was 30 μm as measured by a microscope. One reticulated fiber sheet was peeled off and enlarged twice in the horizontal direction. The measured average distance between the nodal points was 9.5 mm. The value obtained by multiplying the tensile strength by the average distance between the nodes is 4.3. (B) Twenty laminated net-like fiber sheets obtained in the above (A) were laminated and spread by a pin tenter. This pin tenter has two pairs of pin rows with an entrance width of 160 mm and 3 pins.
They are arranged at a divergent angle at an angle of 5 °, so that the one extended at a pin width of 1280 mm is cut (extension magnification 8 times). At the entrance of this pin tenter, the mesh fiber sheet (A) was extended at a speed 1.8 times the moving speed of the pin (overfeed rate 1.7 times) by pushing both ends of the feed to the pin. The fiber was cut at a pin width of 1280 mm to obtain a mesh fiber sheet. (C) 160 ° C of the reticulated fiber sheet obtained in (A) above
In a hot air dryer for 30 seconds to obtain a bulky nonwoven fabric. The physical properties are shown in Table 1. The obtained reticulated fiber sheet was uniform with little unevenness, extremely good heat retention, good drapeability and washing resistance, and had practical properties in general physical properties.

[0035]

[Table-1]

Examples 2 to 7 Using various carbon fine powders (bincho charcoal, bamboo charcoal, activated carbon, carbon black) alone or as a mixture, a reticulated fiber sheet was prepared in the same manner as in Example 1 (A). did. In addition, Table 1 shows the physical properties of the reticulated fiber sheet obtained by performing the spreading by changing the spreading ratio in the same manner as in (B) and (C) of Example 1. The obtained reticulated fiber sheet is a uniform sheet having good heat retention and drapability, as in Example 1.
The washing resistance was also good, and the general physical properties were within a range in which there was no practical problem.

Comparative Examples 1-4 Sheets prepared in the same manner as in Example 1 except that they did not have carbon fine powder had low heat retention.
Except that polybutylene terephthalate containing 30 wt% of Bincho charcoal fine powder having an average particle diameter of 3 μm was used as the carbon fine powder, the reticulated fiber sheet prepared in the same manner as in Example 1 had low heat retention. Met. Next, the reticulated fiber sheet obtained in (A) of Example 1 was extended by the same pin tenter as in (B). At this time, the procedure was the same as that of Example 1 except that the cutting was performed at a point where the width of the pin was 320 mm (extension ratio was 2). As shown in Table 1, the obtained reticulated fiber sheet had a large basis unevenness. Similarly, when the place to be cut was a point where the width of the pin was 2080 mm (extension magnification: 13 times), a part of the pin was partially broken before reaching the place to be cut, and it was confirmed that it was clearly uneven. .

[0038]

As a result of configuring the present invention as described in detail above, the present invention has the following effects. (A) Unlike a conventional sheet in which carbon fine powder has been subjected to a binder treatment, since the carbon fine powder is contained in the net fiber sheet itself, the net fiber sheet for heat insulating material of the present invention is continuously and continuously formed. It is possible to produce stably. (A) Unlike the conventional sheet in which carbon fine powder is fixed with a binder, the carbon fiber powder itself is contained in the mesh fiber sheet itself, so that the heat retention effect is permanently constant and the washing resistance and the like are maintained. No problem with the durability of the device. (C) Unlike the conventional sheet in which carbon fine powder is fixed with a binder, the net fine fiber sheet itself contains carbon fine powder. Therefore, the stiffness of the sheet with the sheet in which carbon fine powder is fixed with the binder. There is no problem such as impairing the flexibility of the sheet. (D) Since the heat retaining effect of the carbon fine powder-containing fiber is high, the thickness of the sheet can be reduced. Therefore, it has a practical heat retaining property without being formed into a laminate as in a conventional product. In addition, it is easy to commercialize various products having an excellent deodorizing effect.

Claims (2)

[Claims] 1. A mesh obtained by extruding a thermoplastic resin containing at least one carbon fine powder selected from the group consisting of Bincho charcoal, bamboo charcoal, activated carbon and carbon black and a foamable substance in a molten state through a slit. A fibrous sheet, wherein the average distance between the bonding points in the sheet is 1 to 50 mm, the tensile strength in the vertical direction is 0.0005 N / dtex or more, and the average fiber diameter is 1 to 150 μm. Extend two or more pieces and use the following formula (1)
And a netting fiber sheet for a heat insulating material obtained by stretching in the horizontal direction at a magnification A satisfying (2). 100m · L ≦ A ≦ 500m · L (1) 2 ≦ A (2) (m is the tensile strength of the reticulated fiber sheet in the vertical direction (N / d
tex). However, when m is 0.01 N / dtex or more, m = 0.01. L indicates the average distance (mm) between the joining points of the reticulated fiber sheet) 2. The reticulated fiber sheet for heat insulating material according to claim 1, wherein the longest diameter of the carbon fine powder is 500 μm, and the content based on the sheet is 2 to 14% by weight.