JP2009167652A - Building heat shielding material excellent in lightweight properties - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a building heat shielding material which is excellent not only lightweight properties and heat shielding properties but also in weatherability including air permeability and water permeability. <P>SOLUTION: The building heat shielding material to be set outside a building is made of a fiber structure using synthetic fibers each having discontinuous hollow portions in a fiber axial direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a building heat shield material excellent in lightness. More specifically, the present invention relates to a heat insulating material for buildings that is used outdoors and is made of a fiber structure that is excellent in light weight and heat ray reflectivity and can easily release hot air.

  In recent years, the technological development of synthetic fibers has made remarkable progress, and fibers with various new functions have been developed. Among them, with regard to the development of fibers or fiber structures that control “heat”, (1) with the declining birthrate and aging, the market for comfortable clothing that can control the environment in clothes has expanded, and (2) the popularity of outdoor sports・ It has attracted attention from the standpoints such as the expansion of the market for thermal insulation clothing due to its establishment, and (3) changes in the structure of various interior and exterior materials (from heavy and long to light, thin and short) as energy conservation increases. In the control of these heats, the fact is that weight reduction is often required.

  The method of supporting these heat control functions on the fiber itself forming the fiber structure is mainly a material (metal or metal oxide, phase transition) having a specific heat different from that of the material forming the fiber (generally a polymer material). Material) and a method of providing an air layer (for example, a hollow portion) having a large specific heat. However, in the former case, in many cases, the apparent specific gravity of the fiber becomes large in order to form a fiber material having an excellent function, that is, the fiber structure tends to be heavy. On the other hand, the method of providing a hollow portion in the fiber like the latter can certainly have light weight, but the hollow portion is crushed and loses its function. In addition, since the hollow portion is made smaller in order to prevent the hollow portion from being crushed, the lightness tends to be inferior.

  For example, the technique about the heat insulation structure used for the inside of the building using a hollow polyester fiber is proposed (refer to patent documents 1). In this technology, a non-woven fabric using the heat insulating effect of the hollow fiber is prepared and used as a heat insulating material on the wall inside the building (for example, attic), but only the heat insulating effect by the air layer of the hollow portion is used. Therefore, there was no breathability and there was no technical guidance or suggestion for outdoor use.

The present inventors have already proposed fiber products (curtains, blinds, or tents) that are excellent in lightness and light shielding properties, which are made of fibers having countless hollow portions in the fibers (see Patent Document 2). In the technology, the innumerable hollow parts in the fiber have high lightness and light reflectivity, and since the hollow part is fine, the hollow part is not easily crushed, and these performances may deteriorate over a long period of time. Absent. However, it is aimed at a fiber structure that does not allow light transmission so as to have high light reflection performance, and furthermore it is weather resistant, especially for outdoor use, technical guidelines in applications exposed to strong wind and rain It was not what I found.
Japanese translation of PCT publication No. 2003-525772 (Claims, paragraph [0046]) JP 2005-248340 A (Claims, paragraph [0090])

  An object of the present invention is to provide a heat insulating material for a building having a fiber structure having a sufficient weather resistance, which is excellent in light weight and heat insulating properties, is suitable for outdoor use, and solves the problems of the above-described conventional technology. There is.

  The present invention employs the following configuration in order to solve the above problems.

  (1) A heat insulating material for buildings for outdoor installation, comprising a fiber structure using a synthetic fiber having hollow portions that are discontinuous in the fiber axis direction.

  (2) The heat insulating material for buildings as described in (1) above, which is a fiber structure using colored synthetic fibers.

  (3) The heat insulating material for buildings as described in (1) or (2) above, wherein the fiber structure is a knitted fabric and / or a net-like material.

  (4) The thermal insulation material for buildings according to any one of (1) to (3), wherein a space filling rate of the synthetic fiber in the fiber structure is 40% by volume to 95% by volume.

  (5) The building heat shielding material as described in any one of (1) to (4) above, wherein a transmitted light rate in a wavelength region of 600 to 1400 nm is 40% or less.

(6) The building heat-insulating material according to any one of (1) to (5), wherein the air permeability is 10 cc / cm ² / second or more.

  (7) The heat insulating material for buildings according to any one of (1) to (6), wherein the heat insulating material is for installation on a roof.

  The heat insulating material for buildings of the present invention is characterized by the fact that the discontinuous hollow portion in the fiber axis direction is innumerable in the fiber cross section perpendicular to the fiber axis direction, that is, the fine hollow portion is a characteristic of the fiber itself. Since there are many in the fiber, a fiber structure with high lightness and excellent light shielding performance is formed, and as a result, it reflects the heat rays emitted from the sun and has high heat shielding performance. ing. In addition, by optimizing the specifications (fabric structure, air permeability, fiber space filling rate) as a fiber structure, it can be used as a heat shield according to the mechanism of the place where it is installed. Or, since it can form a highly water-permeable fiber structure such as rainwater, for example, when passing typhoons with strong wind and rain, it is possible to effectively release rainwater and wind, and coupled with the high breaking strength of the fiber itself, It is possible to obtain a heat shield material that is not easily damaged and has excellent weather resistance. In particular, the heat insulating material for buildings of the present invention can contribute to energy saving in summer (high temperature period) by preventing the temperature rise of the building, and it is easy to carry because it is lightweight in terms of construction and high heat shielding even in a small amount. Since it has performance, it is excellent in flexibility and flexibility.

  As the fiber material forming the building heat insulating material of the present invention, those capable of forming a fibrous structure such as polyolefin, polyamide, polyester, polyacrylonitrile, polyphenylene sulfide, fluorine-based polymer, and cellulose-based polymer are preferably used. Polyester is particularly preferable because it is excellent in durability and weather resistance of the material when installed outdoors and can be easily molded by melt spinning. The polyester referred to in the present invention is a polyester formed by an esterification reaction of a carboxylic acid and an alcohol, and can include a polymer formed from an ester bond of a dicarboxylic acid compound and a diol compound. As polyethylene terephthalate (hereinafter abbreviated as PET polymer), polypropylene terephthalate (also referred to as polytrimethylene terephthalate, hereinafter abbreviated as 3GT polymer), polybutylene terephthalate (also referred to as polytetramethylene terephthalate, hereinafter referred to as PBT). And polyethylene naphthalate (hereinafter abbreviated as PEN polymer), polycyclohexanedimethanol terephthalate (hereinafter abbreviated as PCHDMT polymer), and the like.

  In addition, the polymer formed from the ester bond of these dicarboxylic acid compound and diol compound is copolymerized with other components within the range of not impairing the object of the present invention, that is, high lightness and high light shielding property (heat shielding property). As a copolymerization component, for example, as a dicarboxylic acid compound, for example, isophthalic acid, naphthalene dicarboxylic acid, diphenyl dicarboxylic acid, anthracene dicarboxylic acid, phenanthrene dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenoxyethane dicarboxylic acid, diphenylethane Fragrances such as dicarboxylic acid, adipic acid, sebacic acid, 1,4-cyclohexanedicarboxylic acid, 5-sodium sulfoisophthalic acid, 5-tetrabutylphosphonium isophthalic acid, azelaic acid, dodecanedioic acid, hexahydroterephthalic acid , Aliphatic, alicyclic dicarboxylic acids and their derivatives such as alkyl, alkoxy, allyl, aryl, amino, imino, halides, adducts, structural isomers, optical isomers, and these dicarboxylic acid compounds Of these, one type may be used alone, or two or more types may be used in combination as long as the object of the invention is not impaired.

  Examples of the copolymer component include diol compounds such as ethylene glycol, propylene glycol, butylene glycol, pentanediol, hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, hydroquinone, resorcin, dihydroxybiphenyl, naphthalenediol, anthracene. Aromatic, aliphatic and alicyclic diol compounds such as diol, phenanthrenediol, 2,2-bis (4-hydroxyphenyl) propane, 4,4′-dihydroxydiphenyl ether, bisphenol S, and their alkyl, alkoxy, allyl, Derivatives, adducts, structural isomers, and optical isomers such as aryl, amino, imino, and halide can be listed. One of these diol compounds can be used alone. Also it may be, or object may be used in combination of two or more in a range that does not impair the invention.

  Examples of the copolymer component include a compound having a hydroxyl group and a carboxylic acid in one compound, that is, a hydroxycarboxylic acid. Examples of the hydroxycarboxylic acid include lactic acid, 3-hydroxypropionate, and 3-hydroxybutyrate. Aromatic, aliphatic and alicyclic diol compounds such as acrylate, 3-hydroxybutyrate valerate, hydroxybenzoic acid, hydroxynaphthoic acid, hydroxyanthracenecarboxylic acid, hydroxyphenanthrenecarboxylic acid, (hydroxyphenyl) vinylcarboxylic acid, and their Derivatives, adducts, structural isomers and optical isomers such as alkyl, alkoxy, allyl, aryl, amino, imino, and halide can be mentioned, and one of these hydroxycarboxylic acids may be used alone. Or invention It may be used in combination of two or more in a range that does not impair the purpose.

  Further, the copolymer component may be a polyfunctional molecule having three or more ester-forming functional groups in one molecule in one compound. Examples of the ester-forming functional group include a hydroxyl group, a carboxyl group, Any functional group of an ester bond formed by condensation of a hydroxyl group and a carboxyl group may be used. Examples of the polyfunctional molecule include pentaerythritol, pyromellitic acid, trimethylolpropane, trimellitic acid, and dimethylol. Propionic acid, dipentaerythritol, glycerol, sorbitol, trimethylolethane, trimethylolbutane, 1,3,5-trimethylolbenzene, 1,2,6-hexanetriol, 2,2,6,6-tetramethylolcyclohexanol , Hemimetic acid, trimesic acid, prenitic acid, merophanic acid 5-hydroxyisophthalic acid, 2,5-dihydroxyisophthalic acid, 2,5-dihydroxyterephthalic acid, and the like, and ester compounds thereof, such as alkyl, alkoxy, allyl, aryl, amino, imino, halide, etc. Derivatives, adducts, structural isomers, and optical isomers may be used, and one of these polyfunctional molecules may be used alone, or two or more of them may be combined in a range that does not impair the purpose of the invention. May be used. When these polyfunctional molecules are copolymerized, it is preferable because the number of hollow portions is larger or smaller and densely formed.

  The polyester in the present invention may be a polymer in which one compound such as aromatic, aliphatic, alicyclic, etc. is mainly composed of a hydroxycarboxylic acid compound having both a carboxylic acid and a hydroxyl group. Examples of the polymer include poly (hydroxycarboxylic acid) such as polylactic acid, poly (3-hydroxypropionate), poly (3-hydroxybutyrate), and poly (3-hydroxybutyrate valerate). In addition, these poly (hydroxycarboxylic acids) can be aromatic, aliphatic, alicyclic dicarboxylic acids, or aromatic, aliphatic, alicyclic diol components as long as the object of the present invention is not impaired. May be used, or a plurality of hydroxycarboxylic acids may be copolymerized.

  Of these polyesters, PET-based polymers, 3GT-based polymers, PBT-based polymers, or polylactic acid are more preferable, and PET-based polymers, 3GT-based polymers, and PBT-based polymers are particularly light in weight and have a high melting point. Most preferred because of its excellent deformation resistance.

  As the above-mentioned polyester which is a preferred fiber material, a polyester having an intrinsic viscosity (hereinafter referred to as IV) which is usually used for synthetic fibers can be used. In the case of a PET-based polymer, IV is preferably 0.4 to 1.5, more preferably 0.5 to 1.3. Moreover, if it is a 3GT-type polymer, it is preferable that it is IV0.7-2.0, and it is more preferable that it is 0.8-1.8. Or if it is a PBT-type polymer, it is preferable that it is IV0.8-2.5, and it is more preferable that it is 1.0-2.0. Polyesters used in the present invention include poly (hydroxycarboxylic acids) represented by polylactic acid that are not evaluated in IV, and these are described in terms of weight average molecular weight (hereinafter sometimes simply referred to as average molecular weight). For example, in the case of polylactic acid, those having an average molecular weight of 50,000 to 500,000 are usually used, preferably 100,000 to 300,000, and an average of 150,000 to 250,000 in view of processability and spinnability Molecular weight polylactic acid is more preferably used.

  In the building heat-shielding material of the present invention, the polyester content in the polyester fiber, which is preferable, is preferably 50% by weight or more from the viewpoint of excellent weather resistance. In particular, since the strength in fiber properties can be increased, the polyester content in the fiber is preferably as high as possible, preferably 70% by weight or more, more preferably 80% by weight or more, and even more preferably 85% by weight or more. is there. In addition, since the polyester contains a polymer incompatible with the polyester so as to form a discontinuous hollow portion in the fiber, the content of the polyester in the fiber is preferably 99% by weight or less.

  The fiber made of polyester that is preferably used for the heat insulating material for buildings of the present invention (hereinafter sometimes abbreviated as polyester fiber) is composed of the above-mentioned polyester and a polymer incompatible with the polyester (hereinafter referred to as non-phase). Blended fiber) (sometimes abbreviated as dissolved polymer). Specifically, since the incompatible polymer is incompatible with the polyester, it appears to be island-like in a single fiber cross section perpendicular to the fiber axis direction of the polyester fiber. In the present invention, “incompatible” means that the polyester and the incompatible polymer are not compatible with each other in the molecular chain size order of the polymer, and the average size of islands formed by the incompatible polymer in the polyester (islands) The length corresponding to the shortest diameter) of at least 10 nm. When the polyester and the incompatible polymer are compatible, that is, when the average size of the island-shaped incompatible polymer is 10 nm or less, the obtained fiber is a hollow portion discontinuous in the fiber axis direction (hereinafter referred to as fiber). The hollow part discontinuous in the axial direction may not be simply abbreviated as “hollow part”), or the hollow part necessary to become a lightweight fiber is not sufficiently developed. . That is, the resulting fiber is inferior in lightness.

  A wide variety of polymers can be used as the incompatible polymer in the present invention as long as they are incompatible with polyester as described above. As the polymer, for example, polymers such as polyamide, polyolefin, other vinyl polymers, fluorine polymers, silicone polymers, and the like can be preferably mentioned.

  More specifically, for example, polyolefins or other vinyl polymers in which a monomer having a vinyl group is synthesized by an addition polymerization reaction such as radical polymerization, anionic polymerization, or cationic polymerization, or a ring-opening polymerization reaction can be given. . Polyolefins include homopolymers, copolymers, and derivatives of polyethylene, polypropylene, polybutylene, and polymethylpentene. Other vinyl polymers include polystyrene, polyacrylic acid, polymethacrylic acid, and polymethylmethacrylate. , Polyacrylonitrile, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene chloride, poly (vinylidene chloride), and copolymers and derivatives thereof, etc., of these polymers synthesized by addition polymerization reaction or ring-opening polymerization reaction. Among them, from the viewpoint that the interface with the polyester that is preferable in the above description is easy to peel off due to low critical surface tension, and that a hollow part is easily formed in the fiber, or that the polymer density is low, and that the lightweight property is excellent. And preferred Mention may be made of polyolefin Te.

  Preferred polyolefins include polyethylene, polypropylene, polybutene, polymethylbutene, polymethylpentene, polyethylpentene, polyhexene, and the like. Among these polyolefins, polypropylene, polybutene, and polymethylpentene are particularly preferred because of their high melting point and low critical surface tension. These preferred polyolefins may be either a copolymer in which the monomer accounts for 80 mol% or more, or a homopolymer composed of a single monomer, and more preferably a homopolymer. In particular, the polymethylpentene is most preferable because it has a high melting point of 200 ° C. or higher and a low critical surface tension.

  In addition, polyolefins having a cyclic structure represented by the following chemical formula 1, chemical formula 2, or chemical formula 3, which are synthesized by ring-opening polymerization or addition polymerization of an alicyclic monomer, are preferable.

Here, each of the substituents X and Y is a group selected from hydrogen, an alkyl group, an alicyclic group, a cyano group, an alkyl ester group, and an alicyclic ester group.

  The polyolefin used as the incompatible polymer may be a homopolymer using one kind of monomer alone, or may be a copolymer using a plurality of kinds. A copolymer obtained by copolymerizing a vinyl compound may be used. Specific examples of the copolymer component include vinyl esters of saturated aliphatic carboxylic acids having 2 to 6 carbon atoms, acrylic acid esters and methacrylic acid esters derived from alcohols having 1 to 20 carbon atoms, Unsaturated carboxylic acids such as fumaric acid, maleic acid, itaconic acid, citraconic acid, tetrahydrophthalic acid, methyltetrahydrophthalic acid, nadic acid, acid halides, amides, imides, acid anhydrides and esters of the unsaturated carboxylic acids, Examples thereof include vinyl compounds such as styrene or styrene derivatives, acrylonitrile or acrylonitrile derivatives, vinyloxyalkyl derivatives (alcohol type or carboxylic acid type), or vinyl compounds having an aliphatic cyclic structure (alicyclic structure).

  As the incompatible polymer, a polymer having a high glass transition temperature (Tg) is preferable from the viewpoint of being difficult to be deformed, and a polymer that is preferred today is polystyrene, polyacrylic acid, polymethacrylic acid, polymethyl methacrylate, or polyacrylonitrile. Can be mentioned. In particular, a crosslinked structure of polystyrene or polymethyl methacrylate has a high Tg of 100 ° C. or higher and extremely poor deformability due to the crosslinked structure, and also has a high affinity with the polyester preferred as described above. Since it can disperse | distribute, in the polyester fiber used by this invention, since a fine hollow part can be produced | generated efficiently, the lightweight property of a fiber is high as a result, and it is preferable.

  As the incompatible polymer in the fiber used in the present invention, one of various polymers listed above may be used alone, or a plurality of them may be used in combination as long as the object of the invention is not impaired. good.

  The fiber used in the building heat shield of the present invention is a fiber-forming polymer, particularly preferably a fiber having a hollow portion made of polyester and an incompatible polymer, but discontinuous in the fiber axis direction in the fiber. Since the hollow portion is dense and excellent in lightness, the average dispersion diameter in a single fiber cross section perpendicular to the fiber axis of the incompatible polymer is preferably 5 μm or less. The fiber in the present invention is a fiber in which an incompatible polymer is blended. As described above, when the polymer forming the fiber is the sea component and the incompatible polymer forms the island component, the island component is the fiber axis. Dispersed or elongated in a discontinuous direction. Therefore, the area of the blend interface between the polymer forming the fiber and the incompatible polymer in the fiber of the present invention becomes very large, and when it is a lightweight fiber, it is seen in the fiber cross section perpendicular to the fiber axis. The number of hollow portions that are discontinuous in the fiber axis direction is greatly increased, and as a result, the fiber is excellent in lightness. However, when the island component in the fiber is continuous in the fiber axis direction, that is, when the fiber is a core-sheath composite fiber or a sea-island composite fiber, it is no longer a blended fiber but its composite interface (core-sheath interface or The area of the sea-island interface) is very small compared to the blended fiber, and the hollow part is not generated or is significantly reduced and is very light.

  Further, as described above, when the average dispersion diameter in the fiber cross section perpendicular to the fiber axis of the incompatible polymer is 5 μm or less, the area of the blend interface becomes extremely large as described above, and the discontinuous hollow in the fiber axis direction. In addition to the fact that the number of parts becomes very large and the polyester fiber is extremely excellent in lightness, the generated hollow part is not excessively large and is not likely to be a fiber defect. It is very excellent without degrading. The average dispersion diameter in the fiber cross section perpendicular to the fiber axis of the incompatible polymer is preferably smaller than the single fiber diameter of the fiber, preferably 3 μm or less, more preferably 1 μm or less, and even more preferably 0.5 μm. It is as follows. The ratio of the average dispersion diameter to the diameter of the fiber cross section perpendicular to the fiber axis (in other words, the single fiber diameter) is such that more hollow parts are formed or the fiber physical properties are excellent [single fiber diameter / The average dispersion diameter of the island component] is preferably 5 or more, more preferably 10 or more, and even more preferably 100 or more.

The above-mentioned incompatible polymer preferably has a density of 1.0 g / cm ³ or less because the lightness of the building heat shield is further increased. The incompatible polymer is more suitable as the density is smaller, preferably the density is 0.95 g / cm ³ or less, particularly preferably 0.90 g / cm ³ or less. In particular, polypropylene has a specific gravity of 0.91 g / cm ³ and polymethylpentene has a specific gravity of 0.83 g / cm ^3, which are preferable as having a low density. Further, the average molecular weight of these incompatible polymers is preferably 2,000 to 10,000,000, preferably 5,000 to 5,000,000 in terms of excellent kneadability with polyester, or in view of shape retention and rigidity in fibers. Is more preferable, and it is still more preferable that it is 10,000-1 million.

  The content of these incompatible polymers in the fiber is preferably 1 to 30% by weight in the fiber in terms of more excellent lightness and excellent yarn physical properties of the obtained polyester fiber. It is more preferably 20% by weight, and even more preferably 3 to 15% by weight.

  In addition, these incompatible polymers make it easy to form a hollow part at the blend interface when forming the hollow fiber of the present invention, resulting in a lower specific gravity and excellent lightness. The surface tension is preferably 35 dyne / cm or less, more preferably 33 dyne / cm or less, and particularly preferably 32 dyne / cm or less. Although the critical surface tension of the incompatible polymer is preferably as low as possible, the critical surface tension of the incompatible polymer usually obtained is 10 dyne / cm or more.

  On the other hand, as for the critical surface tension of the polymer constituting the fiber, it is preferable that the releasability from the incompatible polymer is higher when the hollow portion discontinuous in the fiber axis direction is generated as described above. The critical surface tension is preferably higher than 35 dyne / cm, and more preferably 38 dyne / cm or higher. For example, a polyester polymer having a high critical surface tension, such as 44 dyne / cm for a PET polymer and 43 dyne / cm for a 3GT polymer, is preferable. Polylactic acid, which is an aliphatic polyester, has a critical surface tension of about 36 dyne / cm. In addition, copolymer components that can increase the critical surface tension, for example, a copolymer polyester obtained by copolymerizing a component having a polar group such as sulfoisophthalate or a phosphate, co-polymerize these components having a polar group. Compared to unpolymerized polyester, it is preferable because it can have a larger critical surface tension. The critical surface tension is described in G. It is defined by the method.

  The incompatible polymer in the present invention preferably has a melting point (Tm) of 150 ° C. or higher, more preferably 180 ° C. or higher, in that the heat resistance of the polyester fiber is good and the lightness at high temperature is excellent. preferable. Here, the melting point (Tm) means F. It is defined by the method.

As the melt viscosity of the incompatible polymer in the present invention, a polymer having a shear rate of 12.16 sec ^{-1 and} a shear viscosity of 50 to 2000 Pascal seconds ([Pa · second]) is usually used at the melt spinning temperature of the polyester used. , Preferably 80 to 1000 [Pa · sec]. Here, the melt viscosity is described in J. It can be measured by this method.

  The incompatible polymer in the present invention may contain a small amount of additives such as a flame retardant, a lubricant, an antioxidant, a crystal nucleating agent, and a terminal group sealing agent as long as the object of the invention is not impaired.

  The fibers used for the building heat-shielding material of the present invention have poor compatibility between the polymer constituting the fibers and the incompatible polymer, so that fine voids are hardly generated, and the lightness may be poor. Therefore, it is preferable to contain a compatibilizing agent so that the hollow portion formed in the fiber becomes fine. The compatibilizing agent in the present invention means that when an incompatible polymer is contained in a sea component (polyester as a preferable one), the interaction at the blend interface is changed to increase the compatibility between the two, and the dispersion diameter of the incompatible polymer is increased. It is a compound that controls As the compatibilizing agent, a wide variety of compounds such as low molecular weight compounds or high molecular weight compounds can be adopted, and preferred are polyalkylene oxide, poly (alkylene oxide-ethylene) copolymer, poly (alkylene oxide-propylene). ) Copolymers of alkylene oxides and respective vinyl derivatives such as copolymers, or derivatives of polyalkylene oxides, copolymers of alkylene terephthalate and alkylene glycol, copolymers of alkylene terephthalate and poly (alkylene oxide) glycol, copolymers of alkylene terephthalate and polyalkylene diol, And the like.

  The content of these compatibilizers is such that the compatibilization is more effectively expressed, and the fiber properties of the resulting polyester fiber are excellent. It is preferably 10 to 200% by weight, more preferably 20 to 100% by weight.

  The fiber used for the heat insulating material for buildings of the present invention refers to one having an elongated shape and a ratio of the length to the apparent diameter of at least 20. In addition, long fibers (filaments) or short fibers (staples) may be used, but long fibers are preferable in consideration of handleability. In addition, the fiber diameter is preferably 5000 μm or less in terms of the fiber single fiber diameter, which is excellent in fiber physical properties, and further improves the handleability or workability when formed as a building heat shield. More preferably, it is 2000 micrometers or less, and it is still more preferable that it is 1000 micrometers or less. In addition, the lower limit of the fiber diameter is preferably 1.0 μm or more, and preferably 10 μm or more, because the lower limit of the fiber diameter needs to be sufficiently large to form the hollow portion as compared with the size of the incompatible polymer. More preferred.

  The fiber which has a hollow part used for the heat insulating material for buildings of the present invention has a discontinuous hollow part in the fiber axis direction as described above. The building heat shielding material of the present invention is extremely lightweight due to having the characteristic hollow portion, and the sun is blocked by the heat shielding material by extremely irregularly reflecting the heat rays from the sun. Against heat. In addition, since the hollow portions are fine one by one, they are unlikely to be a defect in the fiber structure and are not easily crushed. The reason why the discontinuous hollow part is generated in the fiber axis direction or the details of the mechanism is unclear, but probably the hollow part peels off the blend interface between the polymer forming the fiber and the incompatible polymer. 2) The incompatible polymer splits and spreads without following the deformation of the polymer forming the fiber at the time of spinning or drawing, and (3) the fiber starts from the interface between the polymer forming the fiber and the incompatible polymer. Phenomenon such as exfoliation and splitting, such as the polymer to be formed itself or the composite of the polymer that forms the fiber and the incompatible polymer is torn apart rather than singly, and synergistic effects toward the fiber axis direction It is assumed that a discontinuous hollow part is generated. Furthermore, since this hollow part production | generation expresses randomly and innumerably in a fiber, it is estimated that a hollow part is discontinuous in the fiber axis direction.

  The hollow part discontinuous in the fiber axis direction preferably has an average diameter of the hollow part of 0.10 to 5.0 μm in the fiber cross section perpendicular to the fiber axis. When the average diameter is within this range, the hollow portion is not easily crushed as well as being excellent in lightness. The average diameter is more preferably 0.10 to 3.0 μm, and particularly preferably 0.15 to 1.0 μm. As for the average diameter of the hollow part, the distribution in the fiber cross section can be related to the crushing of the hollow part. In particular, in the fiber cross section perpendicular to the fiber axis, the fiber radius is half and the center of the cross section is shared. When the original fiber cross-sectional shape is divided into the outer layer portion and the inner layer portion of the fiber by the similar cross-sectional shape, the fiber axis in which the average diameter of the hollow portion discontinuous in the fiber axis direction existing in the inner layer portion exists in the outer layer portion It is preferably larger than the average diameter of hollow portions that are discontinuous in the direction. As a result, a hollow portion having a large diameter is disposed in the center portion of the fiber, and a dense hollow portion having a small diameter is disposed in the outer layer portion of the fiber. It can have the property. The average diameter of the hollow portion is described later in C.I. Measured by the term. In particular, the average diameter of the hollow portion discontinuous in the fiber axis direction existing in the inner layer portion is preferably 1.2 times or more larger than the average diameter of the hollow portion discontinuous in the fiber axis direction existing in the outer layer portion.

  In addition, regarding the hollow portion discontinuous in the fiber axis direction, the average number of hollow portions discontinuous in the fiber axis direction having a diameter of 0.10 μm or more in the fiber cross section perpendicular to the fiber axis (that is, the average number of hollow portions) is Since it is preferable that a hollow part is not crushed, it is preferable that it is 100-100,000, It is more preferable that it is 300-50,000, It is especially preferable that it is 500-30,000. The average number of hollow portions is C. It is calculated by the method in the section.

  Moreover, about the hollow part ratio which shows the ratio of the volume of the hollow part in a fiber, the apparent specific gravity of the fiber in this invention is small as mentioned later, and the hollow part ratio of 15% or more from the point which can be excellent in lightweight property It is preferable to have a hollow portion ratio of 25% or more.

  As described above, the fiber used for the building heat-shielding material of the present invention preferably has an apparent specific gravity of 1.20 or less because the heat-shielding material itself is excellent in lightness. Many conventional heat shields are made of fiber materials, but they were heavy with many coating layers on the fiber structure to improve heat insulation, but the apparent specific gravity of the fibers was small. When a heat shielding material is formed, it is very preferable in terms of handling properties, particularly in terms of construction, to have an equivalent bulk (volume) and excellent lightness. The apparent specific gravity of the polyester fiber is preferably 1.10 or less, more preferably 1.05 or less, still more preferably 1.00 or less, and particularly preferably 0.95 or less. Moreover, although the smaller the apparent specific gravity is, the better and preferable, the lower limit is that it can be produced. As a result, the apparent specific gravity is usually 0.40 or more, and it is possible to produce lightweight fibers having a hollow part of 0.50 or more for general use. .

  When formed as a building heat shield, it is preferably strong and does not break easily, and there is no problem in construction. This is related to the breaking strength of the fiber. The breaking strength of the fiber used is preferably 4.0 cN / dtex or more in consideration of these practicalities. The strength of the polyester fiber is preferably 4.2 cN / dtex or more, more preferably 4.5 cN / dtex or more, and even more preferably 4.7 cN / dtex or more. Higher strength is preferable, but fibers with a strength of 10 cN / dtex or less can be obtained at most, and fibers with a strength of 8 cN / dtex or less can be obtained for general use.

  The fibers used in the building heat-shielding material of the present invention retain a small amount of additives such as flame retardants, lubricants, antioxidants, crystal nucleating agents, and end group sealants as long as the object of the invention is not impaired. Also good.

  The building heat-shielding material of the present invention is a fiber structure, but the fiber structure, that is, the form as a fabric is actually used in addition to having light weight, heat-shielding properties, and light-shielding properties as described above. In some cases, a woven fabric and / or a knitted fabric and / or a net-like material are preferable in order to ensure air permeability and water permeability for exhibiting excellent weather resistance. Weaving structures include plain weaves such as broad, voile, lawn, gingham, tropical, taffeta, shantung and desin, twills such as denim, surge and gabardine, satin weaves such as satin and doskin, baskets, panama, mats, hopsacks, Nanako weaves such as Oxford, woven fabrics such as grosgrain, ottoman, hair cord, steep slashes such as French twill, herringbone, broken twill, sloppy slashes, Yamagata slashes, tear slashes, flying slashes, curved syllabaries, Ornamental text, irregular vermilion, stacked vermilion, spread vermilion, vermilion vermillion, day / night vermilion, honeycomb, hack, satin, Niagara, etc. are preferred. The finished double woven fabrics include warp double weaves such as picket and puffer weaves, weft double weaves such as Bedford cords, air weaves and bag weaves. Double weave such can be mentioned as preferred. The knitting structure includes flat knitting such as tengu and single, rib knitting such as rubber knitting and milling, pearl knitting such as lynx, kanoko, pear fabric, accordion knitting, small pattern, lace knitting, fleece knitting, and one piece Weft knitting such as knitting, double knitting, ripple, Milan rib, double picket, warp knitting such as tricot, Russell, Miranese, etc. are preferable. These knitted and / or reticulated materials may be subjected to processing such as conventional scouring, dyeing, and heat setting, as well as physical processing such as flexible processing and heat setting, coating processing, antifouling processing, Chemical treatments such as water repellent, antistatic, flameproof, insecticidal, hygienic, foam resin, and other applications such as microwave, ultrasonic, far-infrared, ultraviolet, and low-temperature plasma Application processing such as may be performed.

  The heat insulating material for buildings of the present invention is for outdoor installation. It is installed outside the building to block the building from being exposed to heat rays, especially sunlight, directly on at least a part of the building. In the outdoors, it is possible to block the irradiation to the walls of the building or to block the irradiation to the roof, but it is more preferable for installation on the roof of the building.

  The building heat shielding material of the present invention is preferably colored in order to prevent the building from being irradiated with heat rays. As the coloring method, either the method in which the heat shielding material of the present invention is formed using a fiber that has been colored in advance, or coloring after the heat shielding material is formed may be used. It is preferable that the heat insulating material for buildings is made of a fiber structure using fibers in which the fibers themselves are colored in advance, in that the properties and the light weight of the heat insulating material itself are more excellent. The colored fibers include those in which a colorant is attached to the fiber surface, or the fiber itself containing a colorant such as a dye or pigment in the fiber at any stage before the fiber is formed. However, it is preferable that the fiber itself is colored at the time when the fiber is formed because it is more durable and can be uniformly colored.

  The heat insulating material for buildings of the present invention preferably has a space filling rate of 40% to 80% by volume of the synthetic fiber in the fiber structure as the fiber structure. In the range of the space filling rate, as described above, in addition to lightness and heat insulation, air permeability and water permeability can be provided, and when the present invention is installed outside a building, an effective heat insulation effect can be obtained. Even when exposed to wind and rain, it is easily surpassed and has excellent weather resistance. Here, the space filling factor is a ratio R (the ratio R to the actual volume (B) that increases in this case when a heat shielding material whose theoretical volume (A) calculated from the area and thickness is known in advance is placed in 4 ° C water. R = B / A) and calculated from the average of the three measurements.

  The building heat-shielding material of the present invention preferably has a transmittance of 40% or less in a wavelength range of 600 nm to 1400 nm, and more preferably 35% or less. The lower the transmitted light rate, the better the desired heat shielding effect in the present invention. The lower the transmittance, the more preferable, and 30% or less is particularly preferable.

Since the heat insulating material for buildings of the present invention has excellent weather resistance as described above, the air permeability is preferably 10 cc / cm ² / second or more, and preferably 20 cc / cm ² / second or more. More preferred. Within this range, even when exposed to wind and rain, wind pressure and rainwater can be easily released, and the durability is excellent.

  Hereinafter, the present invention will be described specifically and in detail by way of examples. Naturally, the present invention is not limited to the following examples. In addition, the physical-property value in an Example was measured with the following method.

A. Measurement of fiber breaking strength Using a Tensilon tensile tester manufactured by Orientec Co., Ltd., using a fiber filament taken out from a heat shield, measured at an initial sample length of 50 mm and a tensile speed of 200 mm / min, and measured an average value measured five times. Value.

B. Measurement of apparent specific gravity of fiber taken out from heat shield and calculation of hollow portion ratio Apparent specific gravity of fiber taken out from heat shield was measured and calculated by the following methods (a) and (b).

(A) When the apparent specific gravity of the fiber is 0.659 or more JIS-L-1013 (1999) 8.17.1 (published by the Japanese Standards Association, chemical fiber filament yarn test method) If the apparent specific gravity of the fiber is 1 or more at a temperature of 20 ° C. ± 0.1 ° C., an aqueous NaBr solution is used. If the apparent specific gravity of the fiber is between 1 and 0.789, water is reduced to the heavy liquid. If the apparent specific gravity of the fiber is between 0.789 and 0.659 in the mixed liquid using ethyl alcohol as the liquid, the mixed liquid using ethyl alcohol as the heavy liquid and n-hexane as the light liquid, The equilibrium state after the fiber was allowed to stand for 30 minutes was confirmed, and as described in 8.17.1 above, the specific gravity value of the mixed liquid that did not float or sink was measured, and the average specific gravity value obtained by measuring five fibers The value was defined as a measured specific gravity value (Q).

(B) When the apparent specific gravity of the fiber is less than 0.659 The weight is measured in advance using 100 g ± 10 g of the heat shield material of the present invention, and a weight whose volume and volume are known is fixed to a tubular knitted fabric in advance. After submerging in ion-exchanged water prepared at 4 ° C ± 1 ° C and defoaming with ultrasonic waves for 5 minutes, measure the volume of the heat shield and measure the average of the specific gravity values of the 10 heat shields Was the measured specific gravity value (Q).

The following formula was used to calculate the hollow ratio.
Hollow portion ratio (%) = 100 (1-Q / R), R = 100 / (S1 / V1 + S2 / V2 + (100-S1-S2) / Vp)
However,
R: Apparent specific gravity of fiber when there is no hollow part S1: Amount of incompatible polymer added (% by weight)
S2: Amount of compatibilizer added (% by weight)
V1: Density of incompatible polymer (g / cm ³ )
V2: density of compatibilizer (g / cm ³ )
Vp: density of the base polymer forming the fiber (g / cm ³ )
For the density (V1, V2, Vp) of the incompatible polymer, the compatibilizing agent, and the base polymer forming the fiber, the average value of the values measured three times based on the above-mentioned (a) floatation method was used. For example, when polyester is used as a base polymer for forming fibers and the polyester is polyethylene terephthalate, 1.34 is obtained for an undrawn yarn and 1.38 is obtained for a drawn yarn. Numbers were used. However, since Alcox (registered trademark, type E-30 or R-150), which is poly (ethylene oxide) manufactured by Meisei Chemical Co., Ltd. used as a compatibilizing agent, which was described later, could not be measured by the floatation method, the density was 1 Calculated as 0.0 g / cm ³ .

C. Confirmation of single fiber diameter, average number of hollow parts, such as average diameter of hollow parts, and discontinuity in the fiber axis direction of hollow parts Single fiber is placed on a carbon tape affixed to a sample stage, and platinum deposition treatment (deposition film) Pressure: 25 to 50 angstroms (processing time: about 120 seconds), and then accelerated with a focused ion beam (FIB) cutting-scanning electron microscope (SEM) observation device (STRAIDB235 manufactured by FEI) at an acceleration voltage of 30 kV By using the Ga focused ion beam, the degree of vacuum is 1. in two steps of rough cutting (current: about 7000 pA, processing time: about 20 minutes) and precision cutting (current: about 3000 pA, processing time: about 4 minutes). When observing the fiber cross section in an atmosphere of 4 × 10 ⁻¹³ Pa, the sample is cut perpendicular to the fiber axis direction, and when observing the fiber longitudinal section, the fiber of the sample The vicinity of the center was cut parallel to the fiber axis direction with a length of 5 times the fiber diameter or more. After cutting, using a scanning electron microscope possessed by the apparatus, in an atmosphere with a vacuum degree of 1.4 × 10 ⁻¹⁹ Pa, with a sample inclination of 52 degrees and an acceleration voltage of 5 kV, a magnification of 200 to 100,000 The fiber cross section (confirmation of fiber diameter) and the fiber longitudinal section (confirmation of discontinuity in the fiber axis direction of the hollow portion) were performed at an arbitrary magnification of twice. Here, the discontinuity was confirmed by the presence of a hollow portion interrupted in the fiber axis direction in one longitudinal sectional photograph. Evaluation was made as ○ when the hollow portion was discontinuous in the fiber axis direction, and × when the hollow portion was continuous or had no hollow portion. Further, the average diameter and the average number of hollow portions discontinuous in the fiber axis direction were calculated by digitizing the image of the fiber cross section in black and white and using WinROOF (version 2.3) manufactured by Mitani Corporation of computer software. . For the average diameter of the hollow portion, calculate the area of all of the top 100 hollow portions from the largest in order of the hollow portion present on the cross-sectional image, and determine the hollow portion calculated by determining that the area is substantially circular from the area value. The average value was calculated from the diameter. Further, the average number of hollow portions having a diameter of 0.1 μm or more is calculated by counting the number of hollow portions having a diameter of 0.1 μm after calculating the diameters of all hollow portions in the fiber cross-sections as described above. The average number of hollow portions was determined for five arbitrary fiber cross-sections that were separated from the fiber diameter by the method. Furthermore, regarding the comparison of the average diameters of the hollow portions that are discontinuous in the fiber axis direction between the outer fiber layer and the inner fiber layer in the fiber cross section perpendicular to the fiber axis, the fiber cross section is considered to be approximately circular, and is half the diameter. The average diameter of the outer layer part and the inner layer part was compared. As a result of comparison, the ratio of average diameters (= [average diameter of hollow parts discontinuous in the fiber axis direction of the inner layer part) / [average diameter of hollow parts discontinuous in the fiber axis direction of the outer layer part]) is 1.0. Less than (less) was evaluated, (△), 1.0 or more was evaluated as good (◯), and 1.2 or more was evaluated as excellent (double circle).

D. Confirmation of incompatibility and average dispersion diameter in fibers of incompatible polymers Dye a block in which fibers are embedded in epoxy resin with ruthenium oxide solution, and cut with an ultramicrotome in a direction perpendicular to the fiber axis. An ultra-thin section having a single-fiber cross section is manufactured and traversed at an arbitrary magnification of 5000 to 1000000 times at an accelerating voltage of 75 kV with a transmission electron microscope (TEM) observation device (H-7100FA type manufactured by Hitachi, Ltd.). Surface observation was performed and the resulting photograph was digitized in black and white. The cross-sectional photograph was image-analyzed with a computer software WinROOF (version 2.3) manufactured by Mitani Corporation to confirm the incompatibility and the average dispersion diameter of the incompatible polymer. The average dispersion diameter was calculated by calculating the areas of all the top 100 incompatible polymers in the descending order of the incompatible polymers present on the cross-sectional photograph, and calculating the non-circularity calculated from the area values as being substantially circular. It calculated by the average value of the diameter of a compatible polymer. Further, regarding incompatibility, if the average dispersion diameter was 10 nm or more, it was judged to be incompatible.

F. Measurement of Glass Transition Temperature (Tgp or Tg) and Melting Point (Tm) Measurement was performed with a differential scanning calorimeter (DSC-2) manufactured by PerkinElmer Co., Ltd., with a sample temperature of 10 mg and a heating rate of 16 ° C./min. The definitions of Tm and Tg are as follows: after observing the endothermic peak temperature (Tm1) observed once at a rate of temperature increase of 16 ° C./min, hold at a temperature of Tm1 + 20 ° C. for 5 minutes, and then rapidly cool to room temperature. (The quenching time and the room temperature holding time are kept for 5 minutes), and when the measurement is again performed at a temperature rise of 16 ° C./min, the endothermic peak temperature observed as a step-like baseline deviation is defined as Tg, and the melting temperature of the crystal And the endothermic peak temperature observed as Tm.

G. Measurement of critical surface tension In a film made of a base polymer or an incompatible polymer forming a fiber, pure water 72.8 dyne / cm, ethyl alcohol (special grade or higher) 22.3 dyne / cm, dioxane 33.6 dyne / cm, hexane 18 Using 5 types of liquids of 4 dyne / cm and 20% aqueous ammonia 59.3 dyne / cm, the liquid droplets were placed on a flat sample under the conditions of 20 ° C., 60% humidity and standing, and the liquid droplets were stationary. Sometimes, the angle formed by the solid plane in contact with the droplet and the surface of the droplet in contact with the air layer is measured as the contact angle θ, and cos θ is plotted against the surface tension of the liquid used (Zisman). (Plot), the critical surface tension was obtained by extrapolating the points where the surface tension when completely wetted, that is, when cos θ = 1, was plotted.

H. Measurement of weight average molecular weight when polylactic acid is used as polyester LC-6A (differential refractometer RID-6A, pump LC-9A, column oven CTO-6A, column Shim-pack, manufactured by Shimadzu Corporation) GPC-801C, -804C, -806C, -8025C), column with chloroform (flow rate 1mL / min, sample volume 200μL (however, 0.5w / w% sample dissolved in chloroform)) Obtained by measuring at a temperature of 40 ° C.

I. Measurement of Intrinsic Viscosity (IV) A sample was dissolved in an orthochlorophenol solution and measured at 25 ° C. using an Ostwald viscometer.

J. et al. Measurement of melt viscosity Using a Capillograph 1B manufactured by Toyo Seiki Co., Ltd., in a nitrogen atmosphere, with a barrel diameter of 9.55 mm, a nozzle length of 10 mm, a nozzle inner diameter of 1 mm, and a shear rate of 12.16 [sec ⁻¹ ] Asked. And the average value of the value calculated | required 5 times was made into the measured value of melt viscosity. Regarding measurement time, 5 measurements were completed within 30 minutes in order to prevent deterioration of the sample.

K. Method for evaluating transmittance of fiber structure at 600 nm to 1400 nm The spectral transmittance characteristic of a fabric sample (fiber structure) with respect to a standard white plate is 600 nm to 1400 nm using an ultraviolet-visible near-infrared spectrophotometer UV-3600 manufactured by Shimadzu Corporation. The heat ray transmittance of the range was measured. In each sample, the average transmittance in the wavelength region was determined from the spectral transmittance characteristics obtained by averaging the results of measuring three times for each measurement location and three times at different measurement locations. And as evaluation of light-shielding properties, those having an average transmittance of 30% or less are double circles (excellent), those having an average transmittance of 30% or more and 40% or less are good (good), and those having an average transmittance of 40% or more are 50% or less. The product was evaluated as Δ (available), and the product exceeding 50% was evaluated as × (inferior).

L. Air permeability
Measurement was performed according to JIS L 1096-1999 8.27.1 A method (fragile type method) using a Fragile type air permeability tester AP-360SM manufactured by Daiei Kagaku Seiki Seisakusho. Test specimens of about 20 cm × 20 cm were collected from five different heat shielding materials (samples), and the specimens were attached to one end (intake side) of the cylinder using a Fragile type tester. When attaching the test piece, the test piece was placed on the cylinder, and a load of about 98 N (10 kgf) was applied evenly from above the test piece so as not to block the intake portion, thereby preventing air leakage at the test piece attachment portion. After attaching the test piece, the suction fan was adjusted so that the inclination type barometer showed a pressure of 125 Pa by an adjusting resistor, and from the pressure indicated by the vertical type barometer and the type of air hole used, The amount of air passing through the test piece was obtained from a table attached to the test machine, and the average value for the five test pieces was calculated.
<Manufacture of a fiber having a hollow portion discontinuous in the fiber axis direction>
[Production of polyester]
To a low polymer obtained by ordinary esterification reaction from 166 parts by weight of terephthalic acid and 75 parts by weight of ethylene glycol, 0.03 part by weight of 85% phosphoric acid aqueous solution as a coloring inhibitor and antimony trioxide as a polycondensation catalyst The polycondensation reaction was performed by adding 0.06 parts by weight of cobalt acetate tetrahydrate as a toning agent to obtain a commonly used polyethylene terephthalate having an IV of 0.70.

  Using this polyester, when performing melt spinning using a biaxial extruder type melt spinning machine, as an incompatible polymer, JSR Co., Ltd. norbornene resin Arton (registered trademark, Example 17, type F5023, 10% by weight of Arton), melt spinning using a die having a spinning temperature of 290 ° C., a hole diameter of 0.3 mm, and a number of holes of 24, and taking up at a take-up speed of 1500 m / min, 722 dtex-24 A polyester multifilament fiber having a round cross-sectional shape was obtained. No yarn breakage occurred during spinning, and the yarn making property was excellent.

When the obtained polyester fiber is stretched, the yarn feeding speed of the yarn feeding roller is 100 m / min, and a length of 50 cm is used for stretching between the first roller and the second roller installed next to the yarn feeding roller. A hot plate heated to 70 ° C. is installed, and the fiber is passed through this surface, so that it is stretched at a draw ratio of 5.0 times, the second roller is heat-treated at 120 ° C., and then threaded with a 25 ° C. cold roller. After cooling, it was wound up. No thread breakage occurred during drawing, and the drawability was excellent.
The properties of the obtained yarn are: strength 5.1 cN / dtex, elongation 21%, specific gravity 0.86, fiber diameter 29.9 μm, average number of hollow parts 7,808, average diameter of hollow parts 0.191 μm, non-phase The average dispersion diameter of the soluble polymer was 0.116 μm, the average dispersion diameter of the single fiber diameter / island component (incompatible polymer) was 257, and the hollow portion was discontinuous in the fiber axis direction and excellent in lightness.

Examples 1-3
The obtained yarn was changed to 55 combined yarns (total fineness of about 7942 dtex). As shown in Table 1, the production density of the net in Example 2 is different from that in Example 1 in that the network structure is different. In Example 3, the fiber structure of Example 1 was colored gray to produce a heat shielding material, and the respective transmitted light rates and space filling rates were measured. Then, the fiber structure was placed on the roof as a heat shield, and the location and temperature of the roof on which the heat shield was not placed were measured to measure the reduced temperature on the roof. On the day of the measurement, the temperature was evaluated as the temperature at the same time (2 pm) under the conditions of weather: clear weather and a temperature of 16.3 ° C. at 2 pm.

  As shown in Table 1, it was found that the reduced temperature on the roof can be controlled by the space filling factor and the color of the heat shield.

  Since the heat shielding material of the present invention reflects heat rays emitted from the sun and has high heat shielding performance, it can be used not only in ordinary households but also in commercial buildings and convenience stores that use large amounts of electricity in the summer. It can contribute to energy saving by improving cooling efficiency. Also, in terms of construction, it is easy to carry because it is lighter than conventional materials, and because it has high heat shielding performance even in a small amount, it is also excellent in flexibility and flexibility, more versatile, suitably Used.

Claims (7)

  A heat insulating material for buildings for outdoor installation, comprising a fiber structure using a synthetic fiber having a hollow portion that is discontinuous in the fiber axis direction.   2. The building heat insulating material according to claim 1, wherein the building heat insulating material is a fiber structure using colored synthetic fibers.   The building heat-insulating material according to claim 1 or 2, wherein the fiber structure is a knitted fabric and / or a net-like material.   The thermal insulation material for buildings according to any one of claims 1 to 3, wherein a space filling rate of the synthetic fiber in the fiber structure is 40% by volume to 95% by volume.   The heat-shielding material for buildings according to any one of claims 1 to 4, wherein a transmittance of light in a wavelength region of 600 to 1400 nm is 40% or less. The thermal insulation for buildings according to any one of claims 1 to 5, wherein the air permeability is 10 cc / cm ² / second or more.   The building heat-shielding material according to any one of claims 1 to 6, wherein the building heat-shielding material is used for installation on a roof.