Heat insulating material having heat storage property and method for producing same

Abstract

To provide a heat insulating material having heat storage characteristics. In particular, the present invention provides a heat insulating material capable of preventing an increase in surface temperature of an electronic device or a housing and having high strength and excellent economic efficiency, and a method for producing the same.SOLUTION: The heat insulating material of the present invention has heat storage properties and is made of a nonwoven fabric in which 0% by weight to 70% by weight of a short fiber (A) having a softening point of 100 °C or higher and 100% by weight to 30% by weight of a core-sheath fiber (B) including a core portion (B1 portion) and a sheath portion (B2 portion) are uniformly bonded per 100% by weight of a total of the following (A) and (B): The core (B1) contains 10% by weight to 90% by weight of a heat storage polymer having a heat absorption temperature of - 20 °C. to 60 °C., and the sheath (B2) contains 90% by weight to 10% by weight of a heat storage polymer having a softening point of 100 °C. or higher, based on 100% by weight of a total of the following (B1) and (B2): SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a heat insulating material having heat storage properties, particularly to a heat insulating material capable of preventing an increase in the surface temperature of an electronic device or a housing, and to a method for manufacturing the same. [Background technology]

[0002] As electronic devices have become smaller and their processing speeds have increased in recent years, heat countermeasures have become increasingly important. In particular, small electronic devices such as smartphones and tablet PCs have become smaller, thinner, and more highly integrated as their processing power has improved. This has created a need not only to protect electronic components from the heat they generate, but also to prevent low-temperature burns on the surface of the housing during use. One solution to these issues has been to place heat-dissipating and insulating materials between the heat-generating element and the housing. A composite sheet has been proposed that layers heat-dissipating and insulating materials between the heat-generating element and the housing.

[0003] For example, Patent Document 1 proposes using a graphite sheet to diffuse heat from a heat source to prevent local temperature increases, while also achieving both heat dissipation and insulation by placing a sheet containing a material with low thermal conductivity, such as silica aerogel, between the graphite sheet and the housing.

[0004] Another example is a thermal insulator that includes a composite layer containing fibers and silica aerogel and resin struts arranged in the thickness direction of the composite layer. This invention aims to obtain a thermal insulator that maintains its structure against compressive stress and suppresses deterioration of thermal conductivity, and it discloses that this thermal insulator is placed between battery cells of an automotive battery (see, for example, Patent Document 2).

[0005] Furthermore, a polymer foam has been disclosed that includes a thermoplastic polymer matrix having dispersed bubbles, an infrared attenuating agent dispersed in the matrix at 2% by weight or more and 5% by weight or less, a brominated flame retardant dispersed in the matrix at 2.5 to 3.5% by weight, and an epoxy stabilizer dispersed in the matrix at at least 0.1% by weight. This invention is primarily intended for application in building and construction applications (see, for example, Patent Document 3).

[0006] Furthermore, a heat insulating material has been disclosed that includes a core-sheath fiber in which the core contains a heat-storing and heat-dissipating material having a melting point or crystallization temperature of 60° C. to 140° C., and the sheath contains a thermoplastic resin having a melting point of 150° C. or higher. This invention is intended for use as thermal insulation around automobile engines (see, for example, Patent Document 4).

[0007] Furthermore, a core-sheath composite fiber has been disclosed in which a side-chain melting type heat storage resin (A) is arranged in the core and a thermoplastic resin (B) is arranged in the sheath, and the difference (ΔT) between the endothermic peak temperature (Tm) during heating and the exothermic peak temperature (Tc) during cooling between 0 and 100°C is 5°C or less. This invention is intended for use in clothing with temperature regulating functions (see, for example, Patent Document 5).

[0008] Furthermore, for example, structures described in Patent Documents 6, 7, 8, 9, 10 and 11 are described as polymers, resin compositions, sheets and molded articles having heat storage properties. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2016-28880 A [Patent Document 2] Japanese Patent Application Publication No. 2017-215014 [Patent Document 3] Patent No. 5785159 [Patent Document 4] Japanese Patent Application Publication No. 2019-143270 [Patent Document 5] JP 2019-77979 A [Patent Document 6] Japanese Patent Application Laid-Open No. 2016-180120 [Patent Document 7] JP 2024-60192 A [Patent Document 8] Japanese Patent Application Publication No. 2022-149721 [Patent Document 9] Japanese Patent Publication No. 2022-149663 [Patent Document 10] Japanese Patent Publication No. 2022-149655 [Patent Document 11] Japanese Patent Publication No. 2022-11733 Summary of the Invention [Problem to be solved by the invention]

[0010] The heat insulating sheet of the invention in Patent Document 1 is both non-flammable and insulating, but is intended for use in railway vehicles. Its use of a powder such as silica aerogel makes it difficult to use as an insulating material for small electronic devices such as smartphones and tablet PCs. Furthermore, this invention also discloses a method of bonding a surface sheet made of inorganic fiber woven fabric or felt to a sheet body having a thickness of 10 to 100 mm with an adhesive resin. However, it is unable to maintain sufficient adhesive strength, resulting in poor durability.

[0011] In the invention of Patent Document 2, the fibers of the composite layer can be made of polyethylene terephthalate, and the resin supports can be made of polystyrene, polypropylene, etc., so no particular consideration is given to their use as insulation for small electronic devices, and there is a problem that they cannot be made small and thin.

[0012] The invention of Patent Document 3 uses a foamable polymer, but since the bubbles mixed in have an average size of 0.1 to 0.4 mm, this material is intended for use in large, thick building materials, and has the problem that it cannot be used to insulate small equipment.

[0013] The invention described in Patent Document 4 uses fibers with a core-sheath structure, but it is preferable to store heat at 60°C to 140°C. However, this type of structure poses problems when used in small devices and when dealing with low-temperature burns.

[0014] The invention of Patent Document 5 uses fibers with a core-sheath structure, but since it is intended for use as clothing, its use as a heat insulating material is not taken into consideration, and therefore density and thermal conductivity are not taken into consideration.

[0015] Furthermore, the above Patent Documents 6, 7, 8, 9, 10 and 11 are inventions relating to heat storage performance structures, and do not disclose or suggest the use of core-sheath fibers or methods for manufacturing heat insulating materials.

[0016] Small electronic devices such as smartphones and tablet PCs are equipped with battery packs that have a modular structure of multiple lithium-ion battery cells, which are secondary batteries. Because lithium-ion batteries are chemically unstable, if a short circuit occurs due to deterioration or some other reason, the secondary battery cell may generate heat and experience thermal runaway. This can then transfer heat to adjacent secondary battery cells, causing successive thermal runaways and leading to a major accident. To prevent this, thin thermal insulation materials are required.

[0017] The present invention aims to solve the above-mentioned problems by providing a heat insulating material that has high heat insulating properties that can effectively block heat, is thin enough to be compatible with small electronic devices such as smartphones and tablet PCs, and is also high-strength and economical, as well as a method for manufacturing the same. [Means for solving the problem]

[0018] In order to solve the above problems, the thermal insulation material of the present invention is a thermal insulation material with heat storage properties, and is composed of a nonwoven fabric in which, per 100% by weight of the total of the following (A) and (B), 0% to 70% by weight of short fibers (A) having a softening point of 100°C or higher and 100% to 30% by weight of core-sheath fibers (B) comprising a core (B1) and a sheath (B2) are uniformly bonded, wherein, per 100% by weight of the total of the following (B1) and (B2), the core (B1) contains 10% to 90% by weight of a heat storage resin having an endothermic temperature of -20°C to 60°C, and the sheath (B2) contains 90% to 10% by weight of a thermoplastic resin having a softening point of 100°C or higher. By using this configuration, a flame-retardant thermal insulation material composed of a nonwoven fabric that is both thin and has thermal insulation properties can be obtained.

[0019] In this case, it is preferable that the tensile strength is 0.5 MPa or more. If the tensile strength is 0.5 MPa or more, stable work can be performed without tearing when the fabric is placed around a secondary battery cell such as a lithium ion battery. The tensile strength is preferably 1 MPa or more, and more preferably 3 MPa or more. If the tensile strength is less than 0.5 MPa, the fabric is prone to tearing and stable work cannot be performed. The tensile strength varies depending on the density at which the fibers are entangled by mechanical bonding, but the upper limit of the tensile strength in the present invention may be set to the tensile strength normally used for nonwoven fabrics, which may be approximately 10 MPa or less.

[0020] Next, in the method for producing a thermal insulating material having heat storage properties of the present invention, when forming the thermal insulating material by uniformly bonding 0% by weight to 70% by weight of short fibers (A) having a softening point of 100°C or higher and 100% by weight to 30% by weight of core-sheath fibers (B) per 100% by weight of the total of (A) and (B) below, the bonding is performed by a mechanical entanglement method or a wet paper-making method. In this case, the mechanical entanglement method may be needle punching or water jet punching.

[0021] By using this manufacturing method, no adhesives or the like are used when manufacturing the nonwoven fabric, so that a flame-retardant heat insulating material can be manufactured with good reproducibility without reducing the thickness or heat insulating properties. [Effects of the Invention]

[0022] The heat insulating material of the present invention is lightweight, has excellent heat resistance and flexibility, and can also ensure the required tensile strength and increase interlaminar strength, so it is highly effective when used in fields where flame retardancy and heat insulating properties are required, such as in insulating components for electronic devices and secondary batteries. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present invention will be described in detail. (short fibers)

[0024] In the present invention, the staple fibers (A) have a softening point of 100°C or higher. In the present invention, the staple fibers (A) can be one or more of synthetic fibers, chemical fibers such as rayon, natural fibers such as cotton, hemp, jute, and wool, or their retread fibers (recycled and recycled fibers). Among these, synthetic fibers are preferred from the viewpoint of durability. Examples of such fibers include thermoplastic fibers such as polyester fibers, polyamide fibers, acrylic fibers, polypropylene fibers, and polyethylene fibers. These fiber materials can be produced by known methods such as wet spinning, dry spinning, or melt spinning. Among these, polyester fibers such as polyethylene terephthalate fibers, polypropylene fibers, and polyamide fibers are preferred from the viewpoint of durability and abrasion resistance. These fibers can be used alone or in combination in any ratio. In particular, polyester fibers are most preferred because the raw polyester can be easily recycled, they are economical, and the resulting insulating material has good strength, flexibility, and processability. Some or all of these thermoplastic fibers may be retread fibers.

[0025] Note that short fibers and long fibers are distinguished by fiber length, and fibers having a length of several hundred mm or less are generally referred to as short fibers, but there is no clear definition. Most natural fibers, except silk threads, are short fibers. Long fibers are produced by chemical synthesis, and short fibers can be obtained by appropriately cutting long fibers produced by chemical synthesis. The short fibers (A) used in the present invention are short fibers obtained by cutting long fibers or fibers of a certain length to the desired fiber length. Their fineness is preferably 0.1 to 10 dtex. The fiber length of the short fibers (A) in the present invention is not particularly limited as described above and can be appropriately determined depending on processability and heat insulating properties. However, a length of 100 mm or less is preferable, and a length of 1 to 80 mm is particularly preferable. (sheath-core fiber)

[0026] In the present invention, the core-sheath fiber (B) must contain, per 100% by weight of the core (B1) and sheath (B2), 10% by weight to 90% by weight of a heat-storing resin having an endothermic temperature of -20° C. to 60° C., and 90% by weight to 10% by weight of a thermoplastic resin having a softening point of 100° C. or higher. Furthermore, the heat insulating material of the present invention is made of a nonwoven fabric in which, per 100% by weight of the core (B1) and sheath (B2), 0% by weight to 70% by weight of staple fibers (A) and 100% by weight to 30% by weight of sheath-core fibers (B) are uniformly bonded.

[0027] The core (B1) in the present invention has an endothermic temperature of -20°C to 60°C, preferably -10°C to 55°C, and more preferably 0°C to 50°C. Examples of heat storage methods for the heat storage material used in the core (B1) include latent heat storage using phase transition heat or crystalline melting, sensible heat storage using specific heat, and chemical heat storage using endothermic and exothermic heat generated during a chemical reaction. Among these, latent heat storage is superior in terms of heat storage density (efficiency), durability, cost, safety, and processability.

[0028] A side-chain melting type can be used as the heat storage resin for the core (B1). The side chains of the side-chain melting type polymer are characterized by being composed of crystalline units that can crystallize with each other. Examples of the core (B1) include heat storage compositions made from the above resins, their crosslinked products, or mixtures with other synthetic resins and additives.

[0029] By adjusting the length of the side chains, it is possible to control the phase transition (melting / solidification) temperature of the side chains and the amount of latent heat absorbed and released during the phase transition. Furthermore, because the main chain does not melt at the melting temperature of the side chains, this type of heat storage resin has excellent shape retention. It also has better heat resistance than main chain melting type heat storage resins.

[0030] The main chain of the side-chain melting type heat storage resin of the present invention has a structure shown in, for example, formulas (1) and (2) in Chemical Formula 1. The side chain of the side-chain melting type heat storage resin of the present invention is composed of, for example, a hydrocarbon group having four or more carbon atoms, and the number of carbon atoms can be selected according to the desired phase transition temperature. The upper limit of the number of carbon atoms is about 30 from the viewpoint of an appropriate phase transition temperature. The hydrocarbon group of the side chain is bonded to the main chain by a methylene group, an ether group, an ester group, or the like. Representative examples of the side-chain melting type heat storage resin of the present invention include heat storage resins manufactured by Sumitomo Chemical Co., Ltd.

[0031] [ka]

[0032] The latent heat storage material usable for the core (B1) can be a heat storage resin composition comprising paraffin and a styrene-based elastomer. As the styrene-based elastomer, a triblock styrene-based elastomer and a diblock styrene-based elastomer can be used in combination, or a styrene-ethylene / propylene-styrene copolymer can be used. By adjusting the blending ratio, a heat storage resin composition can be used that not only has excellent moldability, strength in the operating temperature range, and heat storage performance during phase transition, but also suppresses leakage of paraffin, resulting in an excellent balance of properties.

[0033] Examples of paraffin compounds include aliphatic saturated hydrocarbons (alkanes). While the paraffin compound is not particularly limited as long as it is an aliphatic saturated hydrocarbon (alkane), from the viewpoints of safety and operating temperature, those that are liquid or solid at room temperature are preferred. Among these, saturated hydrocarbons with a main chain of 10 to 30 carbon atoms, particularly linear saturated hydrocarbons, can be used, allowing the phase transition temperature to be arbitrarily selected within the practical temperature range, making them suitable for a wide range of applications. Among these, linear saturated hydrocarbons with a phase transition temperature near room temperature are preferred. Specifically, the paraffin compound is preferably a linear saturated hydrocarbon with a carbon number of 14 to 24, and more preferably a linear saturated hydrocarbon with a carbon number of 16 to 22. The above-mentioned paraffin compounds may be used alone or in combination of two or more. Furthermore, branched saturated hydrocarbons having a branched chain may be used instead of the linear saturated hydrocarbons.

[0034] Styrenic elastomers include both triblock and diblock styrene elastomers. Triblock styrene elastomers are block copolymers that have hard segments made of polystyrene at both ends of the polymer chain. Examples of triblock styrene elastomers include styrene-butadiene / butylene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene / butylene-styrene copolymer, styrene-ethylene / propylene-styrene copolymer, styrene-ethylene / ethylene / propylene-styrene copolymer, and styrene-isobutylene-styrene copolymer. Among these, in terms of heat storage performance during phase transition and moldability, it is preferable to use styrene-ethylene / propylene-styrene copolymer and styrene-ethylene / butylene-styrene copolymer as the triblock styrene elastomer.

[0035] A diblock styrene elastomer is a block copolymer consisting of a hard segment made of polystyrene and a soft segment made of an aliphatic polyolefin. Examples of diblock styrene elastomers include styrene-isoprene copolymer, styrene-butadiene copolymer, styrene-butadiene / butylene copolymer, styrene-ethylene / butylene copolymer, styrene-ethylene / propylene copolymer, and styrene-isobutylene copolymer. Among these, in terms of suppressing bleeding of paraffin in the heat storage resin composition, it is preferable to use a styrene-ethylene / propylene copolymer, a styrene-ethylene / butylene copolymer, or a styrene-ethylene / butylene copolymer as the diblock styrene elastomer.

[0036] The proportion of the paraffin compound in the core (B1) composition is preferably 10 to 49% by weight, and more preferably 15 to 45% by weight, based on 100% by weight of the entire heat storage resin composition. If the proportion of the paraffin compound is within this range, the latent heat performance of the heat storage material can be improved while also imparting strength within the operating temperature range.

[0037] The sheath portion (B2) of the core-sheath fiber (B) in the present invention is a thermoplastic resin having a softening point of 100° C. or higher, preferably 110° C. or higher, and more preferably 150° C. or higher. Any melt-spinnable, fiber-forming polymer may be used, and specific examples of such polymers include polyamides such as nylon 6 and nylon 66, aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and wholly aromatic polyesters, aliphatic polyesters such as polylactic acid and polybutylene succinate, polyolefins such as polyethylene and polypropylene, and polymers containing these as the main component, as well as heat-resistant thermoplastic polymers such as polyphenylene sulfide and polyether ether ketone.

[0038] Furthermore, silane-modified polyolefins can be used as the shell (B2) resin of the present invention. Due to the presence of silanol groups, etc., silane-modified polyolefins undergo crosslinking reactions when exposed to moisture, thereby increasing the softening point while maintaining flexibility.

[0039] When used as a heat insulating material, nylon 6, polyethylene terephthalate, polylactic acid, polyethylene, and polypropylene are more preferable from the viewpoint of flexibility. Polyethylene terephthalate is most preferable from the viewpoint of heat resistance and ease of processing. Small amounts of other optional polymers, antioxidants, antistatic agents, pigments, delustering agents, antibacterial agents, inert fine particles, and other additives may also be added. (Insulating material manufacturing method)

[0040] The method for producing a thermal insulating material having heat storage properties of the present invention is characterized in that when forming a thermal insulating material by uniformly bonding 0% by weight to 70% by weight of short fibers (A) having a softening point of 100°C or higher and 100% by weight to 30% by weight of core-sheath fibers (B) per 100% by weight of the total of (A) and (B) below, the bonding is carried out by a mechanical entanglement method or a wet paper-making method.

[0041] The mechanical entanglement method includes the steps of forming a web using 0 to 70% by weight of short fibers (A) having a softening point of 100°C or higher and 100 to 30% by weight of core-sheath fibers (B), where the total of (A) and (B) is 100% by weight, and bonding the web by mechanical entanglement to form a nonwoven fabric. The web can be produced using a known web-forming device and a conventional web-forming method.

[0042] In this case, the mechanical entanglement may be needle punching or water jet punching. By carrying out mechanical entanglement, the abrasion resistance and interlaminar strength of the heat insulating material can be improved.

[0043] If the mechanical entanglement density is too low, the tensile strength and interlaminar strength of the insulation material will be insufficient, while if it is too high, the bulk density will decrease and the air volume fraction in the insulation material will decrease, resulting in a loss of insulation effect.2 , preferably 80 to 200 times / cm 2 It is preferable to set the following.

[0044] In the present invention, needle punching can be carried out using a known needle punching device according to a known method. After needle punching, the insulating material of the present invention can be obtained by drying in a conventional manner.

[0045] The water jet punch is a device in which a large number of injection holes, each having a diameter of 0.05 to 2.0 mm, are arranged in one or more rows at intervals of 0.3 to 10 mm, and the injection pressure is 90 to 250 kg / cm. 2 This can be done according to a conventional water jet punching method using a water jet punching device G that sprays a high-pressure water stream. The distance between the spray hole and the web is preferably about 1 to 10 cm. After water jet punching, the insulating material of the present invention can be obtained by drying in the same manner as in the conventional method.

[0046] Furthermore, in the present invention, a thermal insulating material can be produced by a wet papermaking method using 0 to 70% by weight of short fibers (A) with a softening point of 100°C or higher and 100 to 30% by weight of core-sheath fibers (B), per 100% by weight of the total of (A) and (B) below. First, the short fibers (A) and the core-sheath fibers (B) are uniformly dispersed in water, and then a slurry is prepared by a process such as screening (removal of foreign matter, lumps, etc.). The final fiber concentration of the slurry is preferably 0.01 to 0.50% by mass. The slurry is then papered on a papermaking machine to obtain a wet paper. During this process, chemicals such as dispersants, antifoaming agents, hydrophilic agents, antistatic agents, polymeric thickeners, release agents, antibacterial agents, and disinfectants may be added.

[0047] Examples of papermaking machines that can be used include those using a single papermaking screen, such as a Fourdrinier, cylinder, or inclined wire, and combination papermaking machines in which two or more papermaking screens of the same or different types are installed online. The nonwoven fabric may also have a multilayer structure of two or more layers. In this case, the nonwoven fabric can be produced by a papermaking method in which wet papers produced by each papermaking machine are laminated, or by a casting method in which one layer is formed and then a slurry containing dispersed fibers is cast onto the layer to form a laminate. When the slurry containing dispersed fibers is cast, the previously formed layer may be in a wet paper state or in a dry state. Furthermore, two or more dry layers can be heat-sealed to form a multilayer nonwoven fabric.

[0048] In the wet papermaking method, a wet paper produced on a papermaking net and squeezed out of water in a wet press section is dried in a dryer such as a Yankee dryer, air dryer, cylinder dryer, suction drum dryer, or infrared dryer to obtain a wetlaid nonwoven fabric. When drying the wet paper, the smoothness of the contact surface is improved by contacting the wet paper with a heated roll such as a Yankee dryer and drying it under heat and pressure. Heat and pressure drying refers to drying the wet paper by pressing it against a heated roll with a touch roll or the like. The surface temperature of the heated roll is preferably 100 to 180°C, more preferably 100 to 160°C, and even more preferably 110 to 160°C. The pressure is preferably 50 to 1000 N / cm, more preferably 100 to 800 N / cm.

[0049] The heat-resistant wetlaid nonwoven fabric of the present invention can be subjected to thermal calendering. During thermal calendering, the roll surface temperature is preferably 100 to 260°C, more preferably 130 to 255°C, and even more preferably 150 to 250°C. The nip pressure during thermal calendering is preferably 190 to 1800 N / cm, more preferably 390 to 1500 N / cm. The processing speed is preferably 5 to 150 m / min, more preferably 10 to 80 m / min.

[0050] In the present invention, when the thermal insulation material has a multilayer structure, it may be a multilayer structure in which each layer has the same fiber blend, or a multilayer structure in which each layer has a different fiber blend. In the case of a multilayer structure, the basis weight of each layer is reduced, which allows the fiber concentration of the slurry to be reduced, improving the formation of the thermal insulation material, and as a result, improving the uniformity of the formation of the thermal insulation material. Furthermore, even if the formation of each layer is uneven, it can be compensated for by stacking them. Furthermore, the papermaking speed can be increased, which also has the effect of improving operability. (base material)

[0051] The heat insulating material of the present invention may optionally use a substrate to further improve its tensile strength and interlayer strength. The substrate may be a cloth or film made of glass fiber or filaments, or a nonwoven fabric made of polyester. Substrates made from these materials are excellent in heat insulating properties and flexibility, making them suitable for use as a substrate for heat insulating materials. (Insulation material)

[0052] In the present invention, the thickness of the heat insulating material is not particularly limited and can be determined appropriately depending on the purpose and use. However, from the viewpoints of economy and ease of processing, the thickness of the heat insulating material is preferably 100 mm or less, more preferably 0.03 mm to 50 mm, even more preferably 0.1 mm to 30 mm, and particularly preferably 0.3 mm to 10 mm.

[0053] The heat insulating material of the present invention has a density of 0.01 to 0.2 g / cm from the viewpoints of heat insulating property, tensile strength, flexibility, processability, etc. 3 The range is preferably 0.01 to 0.1 g / cm 3 It is more preferable that the range is 0.01 to 0.08 g / cm. 3 , and particularly preferably 0.02 to 0.05 g / cm 3 By controlling the density of the heat insulating material in this way, the proportion of air (oxygen) in the heat insulating material can be controlled within a certain range, thereby imparting excellent thinness, heat insulating properties, and tensile strength.

[0054] The heat insulating material of the present invention may be colored with a dye or pigment as needed. As a coloring method, a dye or pigment may be mixed with a polymer before spinning and spun to form a dyed yarn, which may be used as the staple fiber (A) and the sheath-core fiber (B). Alternatively, staple fiber (A) and sheath-core fiber (B) colored by various methods may be used. Alternatively, the heat insulating material itself may be colored with a dye or pigment.

[0055] In order to impart flame retardancy or further improve the tensile strength and interlaminar strength, the heat insulating material of the present invention may be coated or impregnated with an acrylic resin emulsion or an acrylic resin solution containing a known flame retardant such as an acrylic resin emulsion, a phosphate ester-based flame retardant, a halogen-based flame retardant, or a hydrated metal compound, as necessary.

[0056] Various additives can be added to the heat insulating material of the present invention depending on the purpose. Examples of additives include organic phosphorus-based and thioether-based antioxidants, hindered amine-based light stabilizers, benzophenone-based, benzotriazole-based, and benzoate-based ultraviolet absorbers, antistatic agents, bisamide-based, wax-based, and organometallic salt-based dispersants, amide-based and organometallic salt-based lubricants, flame retardants such as bromine-containing organic compounds, phosphoric acid compounds, melamine cyanurate compounds, and antimony trioxide, stretching aids such as low-density polyethylene and linear low-density polyethylene, organic pigments, inorganic pigments, inorganic fillers, organic fillers, and metal ion-based inorganic and organic antibacterial agents.

[0057] The thermal insulation material of the present invention has a thermal conductivity of 0.20 W / m·K or less, preferably 0.15 W / m·K or less, more preferably 0.10 W / m·K or less, even more preferably 0.08 W / m·K or less, particularly preferably 0.05 W / m·K or less, and most preferably 0.03 W / m·K or less. If the thermal conductivity is within the above range, the flame-retardant thermal insulation material 10 of the present invention can exhibit high thermal insulation properties. (Example)

[0058] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples. The measurement methods for each property value in the following examples and comparative examples are as follows. (1) Thickness: Measured in accordance with JIS L-1096 at a load of 0.3 kPa. (2) Density: The thickness and basis weight were measured and calculated using the following formula. The lower the density, the more bulky the insulation material. Density (g / cm 3 )={Basis weight (g / m 2 ) / Thickness (mm)} / 1000 (3) Tensile strength: The tensile strength in the longitudinal direction was measured in accordance with JIS L-1096. From the viewpoints of processability, durability, and abrasion resistance, it must be 0.5 MPa or more, preferably 1 MPa or more, and more preferably 3 MPa or more. (4) Thermal conductivity: Measured in accordance with JIS A-1412-2. (5) Endothermic temperature, heat storage capacity: Using a differential scanning calorimeter (DSC), the heat storage capacity [J / g] of the heat storage resin composition was measured during the temperature rise process at a heating rate of 10°C / min from -40°C to 200°C. The heat storage capacity is 3 J / g or more, preferably 5 J / g or more, more preferably 7 J / g or more, and particularly preferably 10 J / g or more. (6) Durability: In accordance with JIS C-60068-2-14, a 5-cycle thermal shock test was conducted at -55°C and 125°C for 3 hours, and the insulation shape was visually maintained as ◯, and not maintained as ×. (7) Softening point: Measured in accordance with JIS K-7206 First, three types of cores (B1) for use in the present invention were prepared, which will be described as (Reference Example 1), (Reference Example 2) and (Reference Example 3). (Reference example 1)

[0059] The core (B1) of Reference Example 1 was produced by steps (1-1) to (1-3). (1-1) Synthesis of ethylene-methyl acrylate copolymer Ethylene and methyl acrylate were copolymerized in an autoclave reactor at a reaction temperature of 195°C and a reaction pressure of 160 MPa using tert-butyl peroxypivalate as a radical polymerization initiator to obtain an ethylene-methyl acrylate copolymer. The composition and MFR of the copolymer obtained were as follows: number of structural units derived from ethylene: 87.1% (68.8 wt%), number of structural units derived from methyl acrylate: 12.9% (31.2 wt%), MFR (measured at 190°C and 21 N): 40.5 g / 10 min (1-2) Synthesis of ethylene-n-hexadecyl acrylate-methyl acrylate copolymer

[0060] After the inside of a 0.3 L separable flask equipped with a stirrer was replaced with nitrogen, 80.00 g of the ethylene-methyl acrylate copolymer of item (1-1) above, 58.83 g of Kalcol 6098 (Kao Corporation, n-hexadecyl alcohol), and 1.65 g of tetra(n-octadecyl) orthotitanate were added, and the oil bath temperature was set to 130°C, followed by heating and stirring under reduced pressure of 1 kPa for 12 hours to obtain an ethylene-n-hexadecyl acrylate-methyl acrylate copolymer. (1-3) Synthesis of Reference Example 1 (Resin Composition Containing Ethylene-n-Hexadecyl Acrylate-Methyl Acrylate Copolymer and Polypropylene Homopolymer)

[0061] 80 parts by weight of the polymer obtained in (1-2) above, 20 parts by weight of Noblen D101 (Sumitomo Chemical Co., Ltd., propylene homopolymer, melting point 163°C), 0.1 parts by weight of IRGANOX1010 (BASF, pentaerythritol tetrakis[3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]), and 0.1 parts by weight of IRGAFOS168 (BASF, tris(2,4-di-tert-butylphenyl)phosphite) were kneaded using a twin-screw extruder at a kneading temperature of 220°C, a residence time of 2 minutes, and a screw rotation speed of 500 rpm to synthesize Reference Example 1 (a resin composition containing an ethylene-n-hexadecyl acrylate-methyl acrylate copolymer and a polypropylene homopolymer). The endothermic temperature of the resulting heat storage resin composition was 10°C. (Reference example 2)

[0062] Septon 2104 (SEPS, manufactured by Kuraray Co., Ltd., styrene content = 64 wt%) and Kraton G1701M (SEP, manufactured by Kraton Co., Ltd., styrene content = 37 wt%) (final blending ratio 30 / 30 (mass%)) as styrene-based elastomers were supplied to a Plastograph Mixer manufactured by Toyo Seiki Seisakusho, and melt-kneaded for 2 minutes at a temperature of 200°C and a rotation speed of 60 rpm. After that, PCM-18 (octadecane, manufactured by Miki Riken Co., Ltd., melting point = 28°C), a paraffin compound, was supplied so that the blending ratio of PCM-18 to the styrene-based elastomer was 40 / 60 (wt%), and the mixture was melt-kneaded for 5 minutes at a temperature of 200°C and a rotation speed of 60 rpm, to obtain a heat-storage resin composition. The endothermic temperature of the obtained heat-storage resin composition was 45°C. (Reference example 3)

[0063] Septon 2002 (SEPS, manufactured by Kuraray Co., Ltd., styrene content = 30 wt%) as a styrene-based elastomer was supplied to a Plastograph Mixer manufactured by Toyo Seiki Co., Ltd., and melt-kneaded for 2 minutes at a temperature of 200°C and a rotation speed of 60 rpm. After that, PCM-18, a paraffin compound, was supplied so that the mixing ratio of PCM-18 to Septon 2002 was 40 / 60 (wt%), and melt-kneaded for 5 minutes at a temperature of 200°C and a rotation speed of 60 rpm, to obtain a heat-storage resin composition. The endothermic temperature of the obtained heat-storage resin composition was 25°C. (Other materials) (1) High-density polyethylene (HDPE) Novatec HD HE481, manufactured by Japan Polyethylene Co., Ltd., softening point = 123°C (2) Polypropylene (PP) Novatec PP MA3H manufactured by Japan Polypropylene Co., Ltd., softening point = 165°C (3) Hydrocarbon wax (paraffin) Paraffin wax-155, manufactured by Nippon Seiro Co., Ltd., melting point = 69°C (4) Polyethylene terephthalate (PET) TRN-MTJ manufactured by Teijin, softening point = 254°C (5) Nylon 6 1022 UBE, softening point = 220℃ (6) Polyphenylene sulfide (PPS) FZ-2100 manufactured by DIC Corporation, softening point = 280℃ (7) Low-density polyethylene (LDPE) Novatec LD LC-720, softening point = 85℃ (8) Silane-modified high-density polyethylene Linkron HM600A manufactured by Mitsubishi Chemical, softening point = 118°C (9) Nonwoven fabric Milife TY0503FE, manufactured by ENEOS Techno Materials, tensile strength = 25N / 50mm Example 1

[0064] Using Reference Example 1 as the core (B1) and polyethylene terephthalate (PET) as the sheath (B2), the core and sheath were fed into a twin-screw extruder at 10 g / min and 10 g / min, respectively, and melted separately. The spun yarn was obtained by extruding the core-sheath fiber from a core-sheath spinneret at a spinning temperature of 230° C. The spun yarn was cooled and cut to obtain a sheath-core fiber (B) having a core of 50% by weight, a sheath of 50% by weight, a fineness of 2.8 dtex, and a fiber length of 51 mm.

[0065] A spun woven fabric with a weight of 150 g / m2 was fabricated using 70% by weight of the core-sheath fiber (B) and 30% by weight of polyester melt-spun fiber (fineness 2.8 dtex, fiber length 51 mm) as staple fiber (A). 2This web was prepared in a conventional manner with a needle density of 70 needles / cm. 2 The fibers were entangled and fixed by needle punching at a needle depth of 12.0 mm, and then dried in the usual manner to obtain a thermal insulating material. The measured physical properties of the obtained thermal insulating material are shown in Table 1. (Examples 2 to 5, Comparative Example 1)

[0066] Insulating materials were obtained in the same manner as in Example 1, except that the ratio of short fibers (A) to sheath-core fibers (B) was changed or short fibers (A) were not used. The content ratios of short fibers (A) to sheath-core fibers (B) and the results of the obtained insulating materials are shown in Table 1.

[0067] As can be seen from Table 1, for the Examples (Examples 1 to 5) in which the short fibers (A) were 0% to 65% by weight, all of the physical property evaluation results achieved the target values. However, in Comparative Example 1 in which the short fibers (A) were 85% by weight, the heat storage amount was 0, and the target value (3 J / g or more) was not achieved. Therefore, further prototypes were produced and evaluated between 65% and 85% by weight, and it was found that the target values ​​for the physical property evaluation could be achieved if the short fibers (A) were up to 70% by weight. (Examples 6 to 8)

[0068] A thermal insulating material was obtained in the same manner as in Example 1, except that melt-spun fibers of high-density polyethylene (HDPE), polypropylene (PP), and nylon 6 were used instead of polyester melt-spun fibers as the short fibers (A). The types and content ratios of the short fibers (A) and core-sheath fibers (B), and the results of the obtained thermal insulating material are shown in Table 1.

[0069] As can be seen from Examples 6 to 8 in Table 1, not only polyester melt-spun fibers but also high-density polyethylene (HDPE), polypropylene (PP) and nylon 6 were used as short fibers (A), and all of them achieved the target values ​​for the physical property evaluation. (Comparative Examples 2 to 3, Examples 9 to 11)

[0070] A thermal insulating material was obtained in the same manner as in Example 1, except that the ratio of the core (B1) to the sheath (B2) in the core-sheath fiber (B) was changed. The content ratios of short fiber (A), sheath-core fiber (B), core (B1), and sheath (B2), and the results of the obtained thermal insulating material are shown in Table 1.

[0071] As shown in Table 1, in Comparative Example 2, the core (B1) was 5 wt % and the sheath (B2) was 95 wt %, resulting in a heat storage of 0 and not achieving the target value (3 J / g or more). In Comparative Example 3, the core (B1) was 95 wt % and the sheath (B2) was 5 wt %, resulting in a tensile strength of 0.2 MPa and not achieving the target value (0.5 MPa or more). On the other hand, in Examples 9, 10, and 11, all of the targets were achieved. Furthermore, prototypes were produced and evaluated with core (B1) contents ranging from 5 wt % to 30 wt % and from 70 wt % to 95 wt %, and it was confirmed that the target values ​​for all physical property evaluations were met when the core (B1) content was 10 wt % or more and 90 wt % or less. (Examples 12 to 13)

[0072] A thermal insulating material was obtained in the same manner as in Example 1, except that Reference Example 2 or Reference Example 3 was used instead of Reference Example 1 as the core (B1) in the core-sheath fiber (B). The types and content ratios of the short fibers (A), core-sheath fiber (B), core (B1), and sheath (B2), and the results of the obtained thermal insulating material are shown in Table 1.

[0073] As can be seen from Table 1, Example 12 uses the material of Reference Example 2 for the core (B1), and Example 13 uses the material of Reference Example 3 for the core (B1). However, the physical property evaluation results all achieved the target values, and it was found that good results can be obtained even when using these materials. (Examples 14 to 15, Comparative Example 4)

[0074] In Example 1, nylon 6, polyphenylene sulfide (PPS), and low-density polyethylene (LDPE) were used as the sheath (B2) in the core-sheath fiber (B) instead of polyethylene terephthalate (PET). Except for this, a thermal insulating material was obtained in the same manner as in Example 1. The types and content ratios of the short fiber (A), core-sheath fiber (B), core (B1), and sheath (B2), and the results of the obtained thermal insulating material are shown in Table 1.

[0075] As can be seen from Table 1, in Example 14, nylon 6 was used as the sheath (B2), and all of the physical property evaluation results achieved the target values. In Example 15, polyphenylene sulfide (PPS) was used as the sheath (B2), and all of the physical property evaluation results achieved the target values. However, when low-density polyethylene (LDPE) was used as the sheath (B2), the tensile strength was 0.2 MPa, which did not achieve the target value. Nylon 6 has a softening point of 220°C, polyphenylene sulfide (PPS) has a softening point of 280°C, and low-density polyethylene (LDPE) has a softening point of 85°C, confirming the influence of softening point. Further prototypes were produced and evaluated for softening point, and it was confirmed that all of the target values ​​for physical property evaluation were met if the softening point was 100°C or higher. Example 16

[0076] A thermal insulating material was obtained in the same manner as in Example 1, except that instead of using polyethylene terephthalate (PET) as the sheath portion (B2) in the core-sheath fiber (B), silane-modified high-density polyethylene (HDPE) was used and the sheath portion (B2) was cured by a silane coupling reaction. The types and content ratios of the short fibers (A), core-sheath fiber (B), core portion (B1), and sheath portion (B2), and the results of the obtained thermal insulating material are shown in Table 1.

[0077] In Example 16, modified HDPE cured by silane coupling was used as the sheath (B2), and it was confirmed that all target values ​​for physical property evaluation were met. It was found that high-density polyethylene (HDPE) cured in this way can also be used as the sheath (B2). (Examples 17 to 18)

[0078] A thermal insulating material was obtained in the same manner as in Example 1, except that the basis weight was changed. The types, content ratios, basis weights of the short fibers (A), core-sheath fibers (B), core (B1), and sheath (B2), and the results of the obtained thermal insulating material are shown in Table 1.

[0079] As can be seen from Table 1, Example 17 has a basis weight of 400 g / m 2 In Example 18, the basis weight was 1500 g / m 2 However, both of them satisfied all of the target values ​​for the physical property evaluation. In addition, the numerical values ​​obtained were almost the same as those in Example 1. Example 19

[0080] In Example 1, instead of performing needle punching, the water pressure was set to 300 to 800 kg / cm 2 A thermal insulating material was obtained in the same manner as in Example 1, except that the fibers were entangled using a water jet punch while adjusting the fiber diameter within the range. Table 1 shows the types and content ratios of the short fibers (A), core-sheath fibers (B), core (B1), and sheath (B2), and the results of the obtained thermal insulating material.

[0081] In Example 19, entanglement was performed using a water jet punch, but the physical property evaluation values ​​obtained were almost the same as those obtained using the needle punching process in Example 1. Therefore, it was confirmed that the present invention is not limited to needle punching, and that entanglement using a water jet punch is also acceptable. Examples 20 to 22

[0082] In Example 1, the fineness and fiber length of the staple fibers (A) and sheath-core fibers (B) were changed to 1.8 dtex and 3 mm, respectively, and the fibers were dispersed in water at a dispersion concentration of 0.2% by mass for 10 minutes to form a wet paper using a papermaking machine, which was then dried under heat and pressure in a Yankee dryer at a surface temperature of 150°C to obtain a thermal insulating material. The types, content ratios, and basis weight of the staple fibers (A), sheath-core fibers (B), core (B1), and sheath (B2), as well as the results of the obtained thermal insulating material, are shown in Table 1.

[0083] As can be seen from Table 1, in Examples 20 to 22, the heat insulating materials were produced by the wet papermaking method, and it was confirmed that all of the target values ​​for the physical property evaluation were met. As a result, it was found that the wet papermaking method is also acceptable in the present invention.

[0084] Example 23 A thermal insulating material was obtained in the same manner as in Example 1, except that the prepared web was laminated on a nonwoven fabric substrate and entangled by needle punching at a needle density of 70 / cm2 and a needle depth of 12.0 mm according to a conventional method. The types, content ratios, and basis weight of the short fibers (A), core-sheath fibers (B), core (B1), and sheath (B2), as well as the results of the obtained thermal insulating material, are shown in Table 1.

[0085] As can be seen from Table 1, Example 23 has a laminated structure with a nonwoven fabric substrate, but all target values ​​for physical property evaluation were met. As a result, it was confirmed that the present invention may also be applied to a laminated structure with a substrate.

[0086] [Table 1]

[0087] Since the heat insulating material of the present invention is in the form of a sheet, it can be easily processed into an appropriate size, shape, etc. by applying a known method according to the purpose and use, and therefore can be used for a variety of purposes.

[0088] The heat insulating material of the present invention can be used in all applications requiring flexibility and heat insulating properties, such as interior materials for vehicles such as automobiles and freight cars, and transportation equipment such as aircraft and ships, civil engineering and construction materials such as wall members, floor members and ceiling members, packaging materials for refrigerated containers and the like, bedding, and sound absorbing materials.

[0089] In addition, it can be used for a wide range of applications, such as automobile ceiling materials, rear packages, door trim applications, dashboard insulators for automobiles, trains, and aircraft, various heat retaining materials, heat shielding materials, and heat insulating materials, protective clothing, protective gloves, and protective hats for firefighting and high-temperature work, protective sheets for welding sites, weed control materials, speaker diaphragms, and laminated materials for electric carpets. [Industrial Applicability]

[0090] The heat insulating material of the present invention is in the form of a thin sheet, so is flexible and can be easily punched into the required shape, making it useful in a wide range of fields where heat shielding or heat insulating properties are required.

Claims

1. A thermal insulating material having heat storage properties, comprising a nonwoven fabric in which 0 to 70% by weight of short fibers (A) having a softening point of 100°C or higher and 100 to 30% by weight of core-sheath fibers (B) comprising a core (B1) and a sheath (B2) are uniformly bonded together, per 100% by weight of the total of (A) and (B) below, wherein, per 100% by weight of the total of (B1) and (B2) below, the core (B1) contains 10 to 90% by weight of a heat storage resin having an endothermic temperature of -20 to 60°C, and the sheath (B2) contains 90 to 10% by weight of a thermoplastic resin having a softening point of 100°C or higher.

2. 2. The heat insulating material according to claim 1, wherein the heat insulating material has a tensile strength of 0.5 MPa or more.

3. A method for producing a thermal insulating material having heat storage properties, characterized in that when forming the thermal insulating material by uniformly bonding 0 to 70% by weight of short fibers (A) having a softening point of 100°C or higher and 100 to 30% by weight of core-sheath fibers (B) per 100% by weight of the total of the following (A) and (B), the bonding is carried out by a mechanical entanglement method or a wet paper-making method.

4. 4. The method for producing a heat insulating material according to claim 3, wherein the mechanical entangling method is needle punching or water jet punching.

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