JP2008045013A - Light-transmitting flexible heat insulating material and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a heat insulating material having flexibility, light transmission and easy handleability and to provide a method for producing the same. <P>SOLUTION: The light-transmitting flexible heat insulating material has a constitution that foamed cells exist in a polymer matrix and silica gel is filled in the foamed cells. The light-transmitting flexible heat insulating material has an apparent density of the silica gel in the foamed cells of ≤0.6 g/cm<SP>3</SP>, the sizes of foamed cell diameters of ≤1 μm on the average, an average foamed cell density of 10<SP>9</SP>-10<SP>15</SP>cells/cm<SP>3</SP>, a visible light transmittance at 380-780 nm wavelength of ≥50% and a modulus of elasticity of ≤2.0E+10Pa. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light transmissive flexible heat insulating material and a method for producing the same.

  Much of the energy associated with air conditioning in homes and buildings is lost through openings such as windows. Currently used laminated glass and double windows have insufficient heat insulation effects, and vacuum heat insulation windows generally have a high performance, but it is generally difficult to maintain a vacuum for a long period of time. For this reason, the research of the novel heat insulation material which permeate | transmits the light for preventing the heat dissipation from a window is performed widely.

  As a typical example of the light-transmitting heat insulating material, there is silica aerogel which is a dry gel body of extremely low density silica. In general silica airgel, the wet gel body of silica containing a solvent such as alcohol is replaced with another solvent or liquid carbon dioxide, etc., and the temperature is increased and the pressure is raised to bring the solvent into a supercritical state. It is prepared by a technique (supercritical drying) in which the internal solvent is gradually released while keeping the temperature and drying is performed. In the supercritical state, there is no distinction between the gas phase and the liquid phase, and there is no gas-liquid interface, so stress due to interfacial tension does not occur, and drying can be performed while avoiding shrinkage due to this. As a result, a gel body having a general apparent density of 0.05 to 0.2 g / cm 3 and a porosity of 90 to 98% is obtained.

Silica airgel has a high visible light transmittance of over 90% and low thermal conductivity (0.012-0.02 W / mK) comparable to still air, and is known to be able to significantly suppress heat dissipation from windows. ing. This is because the silica airgel has a low density, so the conduction heat transfer is very small, and because many of the pores are 10-20 nm mesopores below the mean free path of the air component gas, the convection heat transfer is also small, Furthermore, the structure of the particles and pores is remarkably smaller than the wavelength of visible light, which is due to the small influence of light scattering and the like.

For example, in the comparison of the heat transmissivity from the window, 5.1 W / m ² K for a single glass window and 1.7-2.9 W / mK for a double-glazed glass (publication of performance values related to thermal insulation of building materials) About Ministry of International Trade and Industry), 1.1-1.3W / m ² K (Nippon Sheet Glass, Spacia) for vacuum insulation windows, Non-Cryst. In Solids 350 and 351 (2004), a value of 0.66 W / m ² K is reported.

  However, silica aerogel is a very brittle solid having a very low mechanical strength due to its low density and lacking flexibility and plasticity. In particular, a monolithic airgel excellent in heat insulation effect and light transmittance is difficult to handle. In addition, since supercritical drying used in the preparation of silica airgel is a high-pressure process, equipment and process running are expensive. Due to these factors, the cost of silica airgel is extremely high, and it has not been widely used as a heat insulating material for windows.

  Many methods for improving manufacturing cost and handling property by making silica aerogel into small pellets have been studied. In addition, low interfacial tension solvents are used as an alternative to supercritical drying, and methods such as modifying bulky molecules on the surface to prevent shrinkage by mutual repulsion to obtain low density silica gel are being studied. Has been. However, the silica airgel obtained by these methods has a problem inferior in heat insulating property and light transmittance as compared with the monolithic silica airgel, and lacks superiority over other heat insulating materials and heat insulating windows.

  As an attempt to improve mechanical strength, Nano Lett., 2, 957 (2002) and the like attempt to improve mechanical strength and handling property by impregnating a silica airgel skeleton with a polymer. However, in these cases, although the mechanical strength is improved, the transparency of the polymer is lost, and since the density is increased, it is considered that the thermal conductivity is also greatly increased.

  Another possible light transmissive insulation is a foamed polymer containing very fine bubbles. In general foamed polymers, the size of the foamed cell is 30 μm or more, and light transmittance cannot be expected. However, if the cell size can be significantly suppressed from the wavelength of visible light, it can be used as a heat-transmitting heat insulating material. Expected to work.

  As such a material, a production method using foaming using a supercritical fluid has already been known. For example, it has a visible light transmission ratio of 70% with respect to a polymer before foaming, and an average pore diameter is 68-. There are 180 nm foamed polymers (see Patent Document 1), and examples of producing foamed polymers having a pore diameter of 2-1 μm and a visible light transmittance of about 70% are shown (see Patent Documents 2 and 3). However, in any case, the pore diameter is larger than that in the case of silica airgel, which is insufficient to achieve both high heat insulation performance and light transmittance. None of the examples mentions heat insulation performance. It is also known that it is relatively difficult to produce such a fine foam structure with good reproducibility. Furthermore, in either case, the production is performed using a batch-type pressure vessel. However, in the production using an extrusion molding machine generally used for preparing a foamed polymer, the size of the foam cell is considerably larger than that of the batch method. It is also known that there are many problems to be solved as a production process.

Relatedly, Yokoyama et al. Generated a nano-sized domain by phase separation in a composite system of a fluoropolymer soluble in supercritical carbon dioxide and another polymer, and eluted one polymer in supercritical carbon dioxide. Thus, a foam having nano-sized pores was prepared (see Patent Documents 4 and 5). However, this method uses an expensive and special supercritical carbon dioxide-soluble polymer and uses a complicated batch process, so it is not suitable for preparing large-scale and large-volume materials. There are many problems in the process of manufacturing the heat insulating material.
JP 2003-176375 A US Patent 6,555,589 B1 US Patent 6,555,590 B1 JP-A-2005-97366 JP-A-2005-290170

  The object of the present invention is to solve the above-mentioned conventional problems, and relates to a heat insulating material that is flexible and light-transmitting and that is easy to handle, and a manufacturing method therefor.

The inventors of the present invention have repeatedly studied to achieve the above object. As a result, the structure in which the foamed cell of the foamed polymer is filled with silica gel, the supercritical carbon dioxide, silicon alkoxide, and the polymer form a uniform phase, the uniform phase is decompressed, the polymer is foamed, and the foam cell The present inventors have found that it can be produced by filling a silicon alkoxide into the inside, and have completed the present invention.

That is, the present invention has a structure in which a polymer base material has foam cells, and the foam cells are filled with silica gel, and the silica gel in the foam cells has an apparent density of 0.6 g / cm ³ or less and a foam cell diameter. The average foam cell density, that is, the number of foam cells per 1 cm ³ is 10 ⁹ to 10 ¹⁵ cells / cm ³ , the visible light transmittance at a wavelength of 380 to 780 nm is 50% or more, and elasticity It is a light-transmitting flexible heat insulating material having a rate of 2.0E + 10 Pa or less.

In the present invention, the silica gel in the foam cell can be an airgel having an apparent density of 0.2 g / cm ³ or less.

  Furthermore, in this invention, the average filling rate of the silica in a foam cell can be 20-100%.

  Furthermore, in the present invention, as the polymer, polylactic acid resin, acrylic resin, olefin resin, polyester resin, polyamide resin, polycarbonate resin, urethane resin, polyvinyl alcohol, vinyl chloride resin, styrene resin. , One or more resins selected from the group consisting of polyacrylonitrile, cellophane, polyvinylidene chloride, fluororesin, polyacetal, polysulfone, ABS, polyether ether ketone, or natural rubber, isoprene rubber, butadiene rubber, 1, 2 -Polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, Tsu containing rubbers, one or two or more may be used selected from elastomer selected from the herd consisting of urethane rubber.

  In the present invention, the polylactic acid resin can be polylactic acid, the acrylic resin can be polymethyl methacrylate or polyacrylic acid, the polyester resin can be polyethyl terephthalate, and the polycarbonate resin can be polycarbonate. .

Furthermore, the present invention includes carbon dioxide, silicon alkoxide, polylactic acid resin, acrylic resin, olefin resin, polyester resin, polyamide resin, polycarbonate resin, urethane resin, polyvinyl alcohol, and vinyl chloride. Resin, styrene resin, polyacrylonitrile, cellophane, polyvinylidene chloride, fluororesin, polyacetal, polysulfone, ABS, one or more resins selected from the group consisting of polyetheretherketone, natural rubber, isoprene rubber, butadiene Rubber, 1,2-polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber A step of mixing one or more polymers selected from an elastomer selected from the group consisting of silicone rubber, fluororubber and urethane rubber under supercritical conditions to form a homogeneous phase, and depressurizing the homogeneous phase. Then, the process of foaming the polymer and filling the silicon alkoxide in the foamed cell, and the method for producing the light-transmitting flexible heat insulating material including the steps of decomposing the silicon alkoxide contained therein.

In the present invention, the silicon alkoxide may be tetraethoxysilane, tetramethoxysilane, tetraisopropoxylsilane, and oligomers thereof.

Furthermore, in the present invention, supercritical drying can be performed in a reduced pressure process.

In the present invention, in the step of decomposing silicon alkoxide, one or more means selected from hydrolysis, thermal decomposition, light irradiation decomposition, and microwave irradiation decomposition can be used.
Furthermore, this invention is a composite_body | complex of the layer which consists of a light-transmitting flexible heat insulating material, and another polymer layer.
Furthermore, this invention is a composition which mix | blended the light transmissive flexible heat insulating material with the soft light transmissive heat insulating material and other polymers.

  As described above, according to the light transmissive flexible heat insulating material of the present invention, it is possible to produce a light transmissive flexible heat insulating material filled with silica gel in the foamed cell of the foamed polymer, and the thermal conductivity is 0.05 W / mK or less.

Embodiments of the present invention will be described as follows.

The polymer used for the light-transmitting heat insulating material of the present invention is preferably a polymer having affinity for supercritical carbon dioxide and silicon alkoxide, having an elastic modulus of 2.0E + 10 Pa or less and capable of swelling and foaming. And mixtures thereof. The copolymer structure may be random, block, or the like, and the stereoregularity may be isotactic, atactic, or syndiotactic.

Olefin resin: α-olefin such as ethylene or propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, or cyclopentene, cyclohexene, cyclooctene, cyclopentadiene, 1,3-cyclohexadiene , Bicyclo [2.2.1] hept-2-ene, tricyclo [4.3.0.1 ^2,5 ] deca-3,7-diene, tetracyclo [4.4.0.1 ^2,5 . ^1,7,10 ] cycloolefin homopolymers such as dodec-3-ene, copolymers of the above α-olefins, and other monomers copolymerizable with α-olefins, vinyl acetate, maleic acid, Examples thereof include copolymers with vinyl alcohol, methacrylic acid, methyl methacrylate, ethyl methacrylate and the like.

  Polyester resins: terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, adipic acid, sebacic acid and other dicarboxylic acid monomers and ethylene glycol, propylene glycol, 1,4-butylene Diols or polyhydric alcohols such as glycol, 1,4-cyclohexanedimethanol, diethylene glycol, polyethylene glycol, polypropylene glycol, polyoxytetramethylene glycol, alkylene oxide adducts of bisphenol compounds or derivatives thereof, trimethylolpropane, glycerin, pentaerythritol Copolymers with monomers, (co) polymers such as hydroxycarboxylic acids such as lactic acid, p-hydroxybenzoic acid, 2,6-hydroxynaphthoic acid, and the like.

  Polyamide-based resin: a polymer having an acid amide bond in a chain obtained by polycondensation of a lactam having three or more members, a polymerizable ω-amino acid, a dibasic acid and a diamine, and specifically, ε-caprolactam , Aminocaproic acid, enantolactam, 7-aminoheptanoic acid, 11-aminoundecanoic acid, 9-aminononanoic acid, α-pyrrolidone, α-piperidone and other polymers, hexamethylenediamine, nonamethylenediamine, undecamethylenediamine, dodeca Polymers obtained by polycondensation with diamines such as methylene diamine and meta-xylene diamine and dicarboxylic acids such as terephthalic acid, isophthalic acid, adipic acid, sebacic acid, dodecane dibasic acid, and glutaric acid, or copolymers thereof. Yes, for example, nylon-4, nylon-6, nylon- , Nylon-8, nylon-11, nylon-12, nylon-6, 6, nylon-6, 10, nylon-6, 11, nylon-6, 12, nylon-6T, nylon-6 / nylon-6, 6 Examples thereof include a copolymer, a nylon-6 / nylon-12 copolymer, a nylon-6 / nylon-6T copolymer, and a nylon-6I / nylon-6T copolymer.

  Other than the above, polycarbonate resin, acrylic resin, urethane resin, polyvinyl alcohol, vinyl chloride resin, styrene resin, polyacrylonitrile, cellophane, polyvinylidene chloride, fluororesin, polyacetal, polysulfone, ABS, polyether ether ketone Resins, natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, many Examples thereof include rubbers such as sulfurized rubber, silicone rubber, fluorine rubber, and urethane rubber, and elastomers. Of the above polymers, polylactic acid, polyacrylic acid and derivatives thereof are preferably used because they have good miscibility with supercritical carbon dioxide and silicon.

Furthermore, in the present invention, a highly transparent material is preferably used. For example, it is desirable that the polylactic acid resin is polylactic acid, the acrylic resin is polymethyl methacrylate or polyacrylic acid, the polyester resin is polyethyl terephthalate, and the polycarbonate resin is polycarbonate.
For the polymer used in the present invention, commonly used additives such as plasticizers, stabilizers, impact resistance improvers, flame retardants, crystal nucleating agents, lubricants, antistatic agents, surfactants, pigments, Dyes, fillers, antioxidants, processing aids, ultraviolet absorbers, antifogging agents, antibacterial agents, antifungal agents, and the like may be added singly or in combination.

The foamed cell diameter in the polymer used in the present invention is 1 μm or less, and the preferred cell diameter is desirably as small as possible, and a structure in which the polymer is uniformly and densely dispersed in the polymer is desirable. The average pore density in the polymer is 10 ⁹ to 10 ¹⁵ / cm ³ .

The density of the silica gel formed in the foamed cell in the present invention is 0.6 g / cm ³ or less, preferably 0.2 g / cm ³ or less. This has a density equivalent to that of silica airgel, and more preferably, the density is 0.15-12 g / cm ³ . This is the density that exhibits the highest heat insulation effect as a silica airgel. In addition, since the effect of the foamed polymer is not changed if the filling rate inside the pores of the produced silica is small, the filling rate is required to be 20% or more, and the structure that completely fills the voids has the thermal conductivity and light transmittance. Desirable from a viewpoint.

  In the present invention, silicon alkoxide is used as a silica precursor, but this is not particularly limited as long as it is compatible with supercritical carbon dioxide and a polymer serving as a matrix, and can form silica by any method. . A mixed system of a plurality of alkoxides can also be used. Specifically, tetrafunctional alkoxides such as tetramethoxysilane, tetraethoxysilane, and tetraisopropoxysilane and their derivatives, trifunctional alkoxides such as methyltrimethylsilane and their derivatives, and oligomers of these alkoxides. Is mentioned. The means for producing silica from these alkoxides is not particularly limited, and examples thereof include hydrolysis, thermal decomposition, light irradiation decomposition, and microwave irradiation decomposition. All of these methods are well known and can be appropriately performed by those skilled in the art.

  The means for producing silica from these alkoxides is not particularly limited, and examples thereof include hydrolysis, thermal decomposition, light irradiation decomposition, and microwave irradiation decomposition. It is also possible to combine a plurality of methods and use a decomposition reaction in a plurality of steps as necessary.

  In order to produce the material of the present invention, first, a polymer molded body and silicon alkoxide are placed in a pressure-controllable container whose temperature can be adjusted, supercritical carbon dioxide is introduced, and the polymer, supercritical carbon dioxide and silicon alkoxide form a homogeneous phase. High pressure conditions In the case of supercritical carbon dioxide, the critical pressure is 7.3 MPa, and the conditions for forming a homogeneous phase with the metal compound and the polymer are generally higher than this, so that the pressure is preferably 9 to 25 MPa. In addition, if a homogeneous phase is generated, it is possible in the present invention to use a subcritical carbon dioxide atmosphere near the critical point. Further, since the critical temperature of supercritical carbon dioxide is 31 ° C., it is preferably carried out at a temperature not lower than the melting temperature of the polymer to be used at 35 ° C. or higher, and when the glass transition temperature of the polymer exceeds the critical temperature, It is preferable to carry out at the glass transition temperature. Further, the time for infiltration is preferably 1 to 48 hours in the case of a polymer molded body, and 5 to 60 minutes in the case of melt kneading.

Next, the pressure inside the pressure vessel is reduced, the polymer, supercritical carbon dioxide and silicon alkoxide are phase-separated, and silica or a precursor is precipitated in the foamed polymer. By controlling the pressure reduction rate and temperature, the silica content with the size of the foam cell can be controlled.
For example, if the pressure is reduced at a rapid rate, the solubility rapidly decreases without the time for the supercritical carbon dioxide and metal compound to diffuse out of the polymer, so the bubbles become larger due to the supercritical carbon dioxide trapped inside, The content of silica increases. On the other hand, if the pressure is reduced at a low speed, the bubble growth is suppressed and the silica content decreases. It is also possible to maintain the silica content while suppressing the bubble size by combining the two appropriately, for example, rapidly reducing the pressure to normal pressure or higher, holding for a certain time, and then slowly reducing the pressure. . In addition, temperature control such as rapid cooling can be combined to change the glass transition / crystallization of the polymer, diffusion and solubility of supercritical carbon dioxide and silicon alkoxide, and adjust the silica content with the size of the foam cell. It is. The pressure reduction rate is generally 20-0.1 MPa / min, and the temperature control is in the range of -196 ° C (liquid nitrogen) -200 ° C.

The deposited silicon alkoxide is converted to silica by a technique such as hydrolysis, thermal decomposition, light irradiation decomposition, microwave irradiation decomposition, or the like after the pressure reduction or in the process of pressure reduction. In the case of hydrolysis, moisture is obtained by a method using water adsorbed on the polymer, a method using water generated by condensation polymerization of the polymer structure, a method of press-fitting with a high-pressure pump, a thermal decomposition of a premixed hydrous compound, etc. And so on. In the process of decompression and phase separation, the decomposition of silicon alkoxide does not need to proceed completely, as long as the solubility in supercritical carbon dioxide or polymer is lowered and the structure can be fixed. It is also possible to combine a plurality of methods as necessary.

If silica is desired to be a silica airgel, the decomposition proceeds at the stage where the alkoxide is deposited in the foam cell to form a skeleton structure of silica, and then the pressure is gradually reduced so as not to fall below the critical temperature of carbon dioxide. . As a result, the carbon dioxide in the cell can be transferred from the supercritical state to the gas phase state, and the silica can be dried while avoiding the generation of the interfacial tension due to the generation of the liquid phase and the collapse of the silica skeleton due to rapid decompression. The temperature in this case is 31 ° C. or higher, preferably 40 ° C. or higher and below the glass transition temperature of the polymer. The pressure reduction rate depends on the size and shape of the polymer, but is generally 1 MPa / min or lower, preferably 0.1 MPa. desirable.

These processes can be carried out continuously using a polymer kneading and extruding apparatus as well as using a polymer molded body in a batch reactor. It is also possible to melt and knead the polymer in the molding machine, introduce supercritical carbon dioxide and silicon alkoxide, and perform a decompression and drying process while controlling the pressure toward the outlet side of the extrusion molding machine.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to these.

In the examples, samples were analyzed as follows.
Average cell diameter and average silica particle size:
A film-like sample was sampled and observed at 10 random locations with a transmission electron microscope (manufactured by JEOL Ltd., TEM-2000FXII), and the average of the measured values was obtained.

Silica content:
It calculated | required by the following formula.
[Silica content (% by mass)] = {[Mass of silica-containing film sample] − [Mass of film alone before silica introduction]} / [Mass of film alone before silica introduction] × 100
The silica content was determined using a differential thermothermal mass simultaneous measurement device (TG / DTA6200 manufactured by SII Nanotechnology).

The apparent density of the silica gel was determined by the following formula.
Density of silica-containing film = 100 / [{100- (silica content)} / density of foamed polymer alone] + [{(silica content) / apparent silica gel density to be obtained}

Light transmittance:
The light transmittance of the film-like sample was measured with an ultraviolet-visible spectrophotometer (JASCO V-570), and the light transmittance was determined based on JIS R 3106.

Heat transfer coefficient:
Measurement was performed using a hot-wire probe type thermal conductivity measuring device (QTM-500, manufactured by Kyoto Electronics Co., Ltd.).

Flexibility:
The value of the elastic modulus at room temperature (around 25 degrees) was determined using a dynamic viscoelasticity measuring device (DMS6100 manufactured by SII Nanotechnology).

  A supercritical carbon dioxide in which tetramethoxysilane is dissolved by placing a polylactic acid film with a thickness of 0.03 mm and 2.0 cm x 2.0 cm in a pressure-resistant container in which tetramethoxysilane has been placed in advance so as not to be immersed in tetramethoxysilane. The fluid was impregnated with polylactic acid and kept under conditions of 80 ° C. and 20 MPa for 24 hours. Under these conditions, the three can form a homogeneous phase. Thereafter, the pressure is reduced by gradual pressure reduction (0.1 MPa / min), phase separation is performed, and the hydrolysis is advanced by water adsorbed on polylactic acid and supplied by polycondensation of the polylactic acid structure. A silica-containing polylactic acid film was obtained. The silica content of the sample was 3.3% by mass, the light transmittance was 68%, and the flexibility and plasticity were almost the same as those of the film before impregnation. It was confirmed by transmission electron microscope (TEM) that bubbles having an average of 1 μm were dispersed almost uniformly in the polymer, and a silica component having an average particle diameter of 50 nm was present in the bubbles. The density of this silica was 0.6 g / cm3. The elastic modulus of this film was 9.3E × 8Pa. The heat transfer coefficient of this film sample was 0.042 W / mK. A schematic diagram of the reaction is shown in FIG.

  A silica gel-containing polylactic acid was obtained in the same manner as in Example 1 except that the pressure reducing method in Example 1 was suddenly reduced (reduced pressure at 2 MPa / min). The sample had a silica content of 2.8% by mass and a light transmittance of 74%, and the flexibility and plasticity were almost the same as those of the film before impregnation. It was confirmed by transmission electron microscope (TEM) that bubbles having an average of 1 μm were dispersed almost uniformly in the polymer as in Example 1, and a silica component having an average particle diameter of 50 nm was present in the bubbles. The apparent density of this silica was 0.6 g / cm3. The elastic modulus of this film was 1.7E × 9Pa. The heat transfer coefficient of this film sample was 0.039 W / mK.

[Comparative Example 1]
Except not impregnating silica in Example 1, a polylactic acid film treated in the same manner was prepared and evaluated. The sample had a silica content of 0% by mass and a light transmittance of 74%, and the flexibility and plasticity were the same as the film before impregnation. As in Example 1, it was confirmed by transmission electron microscope (TEM) that bubbles having an average of 1 μm were dispersed almost uniformly in the polymer. The thermal conductivity of this sample was 0.072 W / mK.

[Comparative Example 2]
A silica wet gel prepared by mixing 4 moles of water, 7.2 moles of methyl alcohol and 0.01 moles of ammonia with 1 mole of tetramethoxysilane was supercritically dried with supercritical carbon dioxide at 20 MPa and 80 ° C. Then, the same decompression process as in Example 1 was performed to prepare silica airgel (diameter 30 mm, height 7 mm). This silica airgel had an apparent density of 0.16 g / cm 3 and a light transmittance of 92%, and was easily broken without any flexibility or plasticity. The thermal conductivity of this sample was 0.014 W / mK.

  The light transmissive flexible heat insulating material of the present invention can be used for packaging films such as heat insulating materials for windows of houses and buildings, heat insulating films for attaching windows, heat insulating materials for automobile windows, and shrink films.

Schematic diagram of a composite material using the light transmissive flexible heat insulating material of the present invention Schematic diagram of reaction in the process of mixing the polymer under supercritical conditions in the present invention to form a homogeneous phase, decompressing the homogeneous phase to foam the polymer and filling the foamed cell with silicon alkoxide

Claims (11)

The polymer base material has foam cells, and the foam cells are filled with silica gel. The silica gel in the foam cells has an apparent density of 0.6 g / cm ³ or less, and the average size of the foam cells is 1 μm. Hereinafter, a light-transmitting flexible heat insulating material having an average foamed cell density of 10 ⁹ to 10 ¹⁵ cells / cm ³ , a visible light transmittance of 50% or more at a wavelength of 380 to 780 nm, and an elastic modulus of 2.0E + 10 Pa or less. The light-transmitting flexible heat insulating material according to claim 1, wherein the silica gel in the foam cell is an airgel having an apparent density of 0.2 g / cm ³ or less.   The light-transmitting flexible heat insulating material according to claim 1 or 2, wherein an average filling rate of silica in the foam cell is 20 to 100%.   The polymer is polylactic acid resin, acrylic resin, olefin resin, polyester resin, polyamide resin, polycarbonate resin, urethane resin, polyvinyl alcohol, vinyl chloride resin, styrene resin, polyacrylonitrile, cellophane, poly One or more resins selected from the group consisting of vinylidene chloride, fluororesin, polyacetal, polysulfone, ABS, polyether ether ketone, or natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene rubber, styrene-butadiene Rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluorine rubber, urethane rubber One or two or more at a light transmissive flexible insulation material selected from elastomer selected from the herd that.   5. The light transmitting property according to claim 4, wherein the polylactic acid resin is polylactic acid, the acrylic resin is polymethyl methacrylate or polyacrylic acid, the polyester resin is polyethyl terephthalate, and the polycarbonate resin is polycarbonate. Flexible insulation. Carbon dioxide, silicon alkoxide, polylactic acid resin, acrylic resin, olefin resin, polyester resin, polyamide resin, polycarbonate resin, urethane resin, polyvinyl alcohol, vinyl chloride resin, styrene resin, poly One or more resins selected from the group consisting of acrylonitrile, cellophane, polyvinylidene chloride, fluororesin, polyacetal, polysulfone, ABS, polyetheretherketone, or natural rubber, isoprene rubber, butadiene rubber, 1,2-polybutadiene Rubber, styrene-butadiene rubber, chloroprene rubber, nitrile rubber, butyl rubber, ethylene-propylene rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, rubber A step of mixing one or two or more polymers selected from an elastomer selected from the group consisting of a base rubber and a urethane rubber under supercritical conditions to form a homogeneous phase, depressurizing the homogeneous phase, A method for producing a light-transmitting flexible heat insulating material, comprising a step of foaming and filling a silicon cell with a silicon alkoxide, and a step of decomposing the silicon alkoxide contained therein. The method for producing a light-transmitting flexible heat insulating material according to claim 6, wherein the silicon alkoxide is tetraethoxysilane, tetramethoxysilane, tetraisopropoxylsilane, or an oligomer thereof. The method for producing a light-transmitting flexible heat insulating material according to claim 6 or 7, wherein supercritical drying is performed in a reduced pressure process. The step of decomposing silicon alkoxide is described in any one of claims 6 to 8 using one or more of means selected from hydrolysis, thermal decomposition, light irradiation decomposition, and microwave irradiation decomposition. Manufacturing method of light-transmitting flexible heat insulating material. 6. A composite of a layer made of the light-transmitting flexible heat insulating material according to claim 1 and another polymer layer. A composition comprising the light transmissive flexible heat insulating material according to any one of claims 1 to 5 blended with another polymer.

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