Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D101/00—Coating compositions based on cellulose, modified cellulose, or cellulose derivatives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/65—Additives macromolecular
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L59/00—Thermal insulation in general
  • F16L59/02—Shape or form of insulating materials, with or without coverings integral with the insulating materials

Definitions

• the present invention relates to a heat insulating paint and a heat insulating material using silica airgel.
• Silica airgel is a porous material in which silica fine particles are linked to form a skeleton and have a pore structure of about 10 to 50 nm.
• the thermal conductivity of silica airgel is lower than that of air. For this reason, the development of a heat insulating material utilizing the high heat insulating properties of silica airgel is in progress.
• Patent Document 1 describes an article containing silica airgel bonded by a water-dispersible polyurethane and having a thermal conductivity of 0.025 W / m ⁇ K or less.
• Patent Document 2 discloses an aqueous dispersion of silica airgel particles including silica airgel particles, organic nanofibers having an anionic functional group, a water-soluble nonionic surfactant, a water-soluble resin, and water. And drying it to produce thermal insulation.
• Patent Literature 3 describes a heat insulating material including silica airgel particles, a hydrophilic adhesive such as a phenol resin, and an amphiphilic compound (surfactant) having a hydrophilic group and a hydrophobic group.
• silica aerogels used as heat insulators have hydrophobic parts on the surface to prevent moisture and the like from entering inside and crushing the pores.
• a urethane binder is used for the purpose of fixing silica airgel or the like
• a hydrophobic solvent is used as a dispersion medium
• the solvent permeates the pores of the silica airgel.
• a coating material is prepared by adding silica airgel to a dispersion in which a urethane binder is dispersed in water instead of a hydrophobic solvent.
• silica airgel has a hydrophobic portion on its surface, and therefore is not easily adapted to water.
• the heat insulating material described in Patent Document 2 contains organic nanofibers.
• the fibrous substance is entangled around the silica airgel, and exhibits a thickening effect and an effect of suppressing separation of the silica airgel from the dispersion medium.
• a fibrous substance when a fibrous substance is blended, it becomes a heat transfer path, and as the blending amount increases, the thermal conductivity of the heat insulating material increases and the heat insulating property decreases. I understood.
• the present invention has been made in view of such circumstances, and it is an object of the present invention to provide a heat insulating paint having good coatability, in which silica airgel hardly separates. Another object is to provide a heat insulating material which is easy to manufacture and has excellent heat insulating properties by using the heat insulating material paint.
• the heat insulating coating material of the present invention is characterized by having silica airgel, an aqueous emulsion binder, and a polysaccharide.
• the heat insulating material of the present invention has a cured product of the heat insulating coating material of the present invention described in the above (1) on at least a part of the surface and inside of the substrate.
• the paint for heat insulating material of the present invention has a polysaccharide.
• the polysaccharide is one in which one or more monosaccharides are glycoside-linked, and has high viscosity.
• the viscosity of the coating material is increased, and the silica airgel is hardly separated from the dispersion medium. Thereby, the silica airgel is stably held in the paint.
• the viscosity of the paint is high, it is difficult to drip, so that the paint is easily applied to the base material.
• Polysaccharides suppress the separation of silica airgel by increasing the viscosity due to entanglement of molecular chains. For this reason, even if the polysaccharide is blended, unlike the fibrous substance, a heat transfer path is hardly formed. Therefore, even if the blending amount of the polysaccharide is increased, the heat insulating property does not easily decrease.
• silica airgel has a hydrophobic portion on its surface, thereby maintaining the pore structure.
• the hydrophobic portion selectively binds to the hydrophobic portion of the silica airgel, and the hydrophilic portion is disposed so as to surround the silica airgel, thereby protecting the silica airgel. It becomes like a colloid. This action also suppresses the separation of the silica airgel from the dispersion medium and improves the dispersibility of the silica airgel. As a result, the time required for dispersion can be reduced, and coating can be easily performed.
• polysaccharides having a hydrophilic portion are less likely to enter the pores of silica airgel.
• the silica airgel can be easily dispersed, and the time of the dispersion step can be shortened.
• the silica airgel is difficult to separate from the dispersion medium such as water after preparing the coating material, restrictions on the working process are reduced. That is, since the next step does not need to be performed immediately after preparing the paint, the next step can be performed after several days.
• coating by a coating machine becomes possible, and it can respond to continuous production.
• the viscosity of the paint is high, it can be easily applied to a film-like base material, and various types of heat insulating materials can be easily manufactured. Polysaccharides are also used as additives for foods and the like, and are easily available and inexpensive. Therefore, according to the heat insulating material paint of the present invention, the heat insulating material can be manufactured at low cost.
• Patent Documents 2 and 3 describe that a surfactant is blended.
• the surfactant has a protective colloid property, its viscosity is poor, so that the effect of improving the coatability is small.
• the heat insulating material of the present invention is easy to manufacture because the heat insulating paint of the present invention, which has excellent coatability, is used.
• the cured product constituting the heat insulating material of the present invention contains silica aerogel, and also contains a polysaccharide in which a heat transfer path is less likely to be formed than a fibrous substance. Therefore, the thermal conductivity of the cured product can be reduced, and a heat insulating material having high heat insulating properties can be realized. For example, when a polysaccharide having a long main chain and easily causing entanglement of molecular chains is used, the retention of silica airgel becomes higher. Thereby, falling off of the silica airgel (so-called powder dropout) in the cured product can be suppressed. In addition, cracks and the like can be suppressed by increasing the strength of the cured product.
• heat-insulating paint and the heat insulating material of the present invention will be described.
• the heat-insulating paint and heat-insulating material of the present invention are not limited to the following forms, and various modifications and alterations that can be made by those skilled in the art without departing from the gist of the present invention. Can be implemented.
• the coating material for a heat insulating material of the present invention (hereinafter, appropriately referred to as “paint”) has silica airgel, an aqueous emulsion-based binder, and a polysaccharide.
• the structure, shape, size, etc. of the silica airgel are not particularly limited.
• the diameter of the silica fine particles (primary particles) forming the skeleton of the silica airgel is preferably about 2 to 5 nm, and the size of the pores formed between the skeletons is preferably about 10 to 50 nm.
• Most of the pores are so-called mesopores of 50 nm or less. Since the mesopores are smaller than the mean free path of the air, the convection of the air is restricted and heat transfer is hindered. Thereby, the silica airgel has high heat insulating properties.
• the shape of the silica airgel is spherical or irregularly shaped lump, but spherical is preferable.
• the dispersibility is improved, so that it is easy to make a paint.
• the close-packing is easy, the filling amount can be increased, and the effect of improving the heat insulating property is increased.
• the surface area is reduced, the amount of the binder having a relatively large thermal conductivity can be reduced, which leads to an improvement in heat insulation.
• the average particle diameter is desirably about 1 to 200 ⁇ m.
• the small-diameter silica airgel enters the gap between the large-diameter silica airgels, so that the filling amount can be increased, and the effect of enhancing the heat insulating property is increased.
• the silica airgel has a hydrophobic portion on at least the surface out of the surface and the inside.
• This type of silica airgel can be manufactured by performing a hydrophobic treatment such as imparting a hydrophobic group in a manufacturing process.
• a hydrophobic treatment such as imparting a hydrophobic group in a manufacturing process.
• permeation of moisture or the like can be suppressed, so that the pore structure is maintained and the heat insulating property is not easily impaired.
• the method for producing the silica airgel is not particularly limited, and the drying step may be performed at normal pressure or may be performed at supercritical conditions. For example, if the hydrophobizing treatment is performed before the drying step, supercritical drying is not required, that is, drying may be performed at normal pressure, and therefore, production may be easier and at lower cost.
• silica airgel can be produced through an aqueous silica sol preparation step ⁇ an emulsion formation step ⁇ a gelation step ⁇ a solvent replacement step ⁇ a hydrophobic treatment step ⁇ a drying step.
• the emulsion forming step the aqueous silica sol obtained in the previous step is dispersed in a hydrophobic solvent to form a W / O emulsion (an emulsion in which water droplets are dispersed in the hydrophobic solvent).
• the silica sol which is a dispersoid, becomes spherical due to surface tension or the like, and is gelled in a subsequent step, whereby a spherical gelled body can be obtained.
• polysaccharides examples include carboxymethyl cellulose, carboxyethyl cellulose, carboxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, xanthan gum, agarose, and carrageenan. Above all, from the viewpoint of suppressing infiltration of the silica airgel into the pores, those having high compatibility with water are desirable. For example, when the solubility parameter (SP value) is 21 or more, It is desirable to adopt a close one. Polysaccharides having an SP value close to that of water have high compatibility with water (is easily soluble in water). According to the simulation software described later, the SP value of water is estimated to be 29.7.
• polysaccharides having an SP value of 21 or more have high hydrophilicity and low affinity with hydrophobic pores, and thus do not easily enter the pores of silica airgel. More preferably, the SP value of the polysaccharide is 34 or more. On the other hand, the SP value of the polysaccharide is desirably 50 or less.
• a value calculated by a material property simulation software “J-OCTA (registered trademark)” manufactured by JSOL Corporation is used as a solubility parameter.
• the SP value is estimated using the group contribution method.
• the polysaccharides those with a long main chain and no or short side chains have more entangled molecular chains. Thereby, the holding property of the silica airgel is increased, and thus the silica airgel in the cured product can be prevented from falling off. Further, by increasing the strength of the cured product, cracks and the like can be suppressed. From such a viewpoint, carboxymethyl cellulose is particularly preferable.
• the polysaccharide desirably has a hydrophilic part and a hydrophobic part.
• the molecular weight of the polysaccharide is large.
• the molecular weight is preferably 70,000 or more, 100,000 or more, and more preferably 300,000 or more.
• the content is desirably 0.08% by mass or more when the whole coating material is 100% by mass, because a desired thickening effect is exhibited. It is more preferable that the content be 0.2% by mass or more. On the other hand, if the viscosity is too high, the coatability may be reduced. Therefore, the carboxymethylcellulose content is preferably 4% by mass or less when the whole coating material is 100% by mass. It is preferably at most 2% by mass, more preferably at most 0.6% by mass.
• the aqueous emulsion binder is an emulsion binder using water as a solvent.
• the aqueous emulsion-based binder is emulsified by introducing a surfactant or a hydrophilic group.
• a surfactant or a hydrophilic group volatilize at the time of drying to lower the hydrophilicity and become less soluble in water.
• the method of emulsification may be a forced emulsification type using a surfactant as an emulsifier, or a self-emulsification type in which a hydrophilic group is introduced.
• the binder component may be a resin or rubber. That is, it may be a resin emulsion or a rubber emulsion.
• the resin include an acrylic resin, a urethane resin, and a mixture of an acrylic resin and a urethane resin.
• the rubber include styrene butadiene rubber, nitrile rubber, silicone rubber, urethane rubber, and acrylic rubber. From the viewpoint of softening the cured product of the paint, urethane resin, styrene-butadiene rubber and the like are preferred.
• the binder component may be crosslinked using a crosslinking agent or the like. That is, the heat insulating coating material of the present invention may contain other components such as a crosslinking agent in addition to the silica airgel, the aqueous emulsion binder, and the polysaccharide.
• the coating material for a heat insulating material of the present invention may be prepared by adding silica aerogel, an aqueous emulsion-based binder, a polysaccharide and, if necessary, an additive to water and stirring.
• silica airgel having a hydrophobic portion on its surface or inside is not easily adapted to water.
• the specific gravity is small, it easily floats on water and is hardly dispersed. Therefore, in consideration of the dispersibility of the silica airgel, it is desirable to increase the viscosity of the liquid by adding an aqueous emulsion binder and a polysaccharide to water before adding the silica airgel.
• the stirring may be blade stirring, but may be positively applying a shearing force or applying ultrasonic waves.
• a rotation orbital stirring device or a media type stirring device may be used.
• the heat insulating material of the present invention has a cured product of the above-described heat insulating material paint of the present invention on at least a part of the surface and inside of the base material.
• the material of the base material include a cloth such as a non-woven fabric and a resin.
• the shape of the substrate is not particularly limited, and may be a film or a molded product.
• the heat insulating material of the present invention can be produced by applying the heat insulating material coating material of the present invention to the surface of a substrate and drying the coating film.
• a coating machine such as a bar coater, a die coater, a comma coater (registered trademark), a roll coater, or the like, or a spray may be used.
• the base material may be immersed in the heat insulating coating material of the present invention and then dried.
• a part of the applied paint impregnates the inside of the substrate.
• the cured product of the heat insulating paint contains silica airgel, an aqueous emulsion binder, and a polysaccharide. Each component is as described in the heat insulating paint of the present invention.
• the content of the silica airgel in the cured product is desirably 40% by mass or more when the mass of the entire cured product is 100% by mass, from the viewpoint of improving the heat insulating properties of the cured product. More preferably, it is 50% by mass or more and 65% by mass or more.
• the content of the silica airgel is desirably 75% by mass or less when the mass of the entire cured product is 100% by mass.
• Examples 1 to 3 First, in water, a urethane resin emulsion (“Permarin (registered trademark) UA-368, manufactured by Sanyo Chemical Industries, Ltd., solid content: 50% by mass)” as an aqueous emulsion-based binder, and carboxymethyl cellulose (CMC: (SP value 34.4, molecular weight 380,000) and stirred. Thereto, spherical silica airgel (average particle diameter: 10 ⁇ m) was added and stirred to prepare a coating. Silica airgel is produced according to the method described in the above-mentioned Japanese Patent No. 4960534, and has a hydrophobic portion on the surface and inside. Three types of paints were prepared by changing the amount of CMC added, and used as paints of Examples 1 to 3. The paints of Examples 1 to 3 are included in the concept of the paint for heat insulating material of the present invention.
• a urethane resin emulsion (“Permarin (registered trademark) UA-368, manufactured by San
• Example 4 A coating material of Example 4 was prepared in the same manner as in Example 1 except that the type (molecular weight) of CMC was changed. In Example 4, CMC having a molecular weight of 100,000 was used. The paint of Example 4 is included in the concept of the paint for heat insulating material of the present invention.
• Example 5 A coating material of Example 5 was prepared in the same manner as in Example 3 except that xanthan gum (SP value: 34.7, molecular weight: 2,000,000 or more) was used instead of CMC as a polysaccharide.
• the paint of Example 5 is included in the concept of the paint for heat insulating material of the present invention.
• Example 6 Except for using hydroxyethylcellulose (HEC: “Natrosol (registered trademark) HH” manufactured by Ashland, SP value 31.7, molecular weight 1.3 million) instead of CMC as the polysaccharide, A paint of Example 6 was prepared. The paint of Example 6 is included in the concept of the heat-insulating paint of the present invention.
• HEC hydroxyethylcellulose
• Example 7 Except for using hydroxypropylcellulose (HPC: "Klucel (registered trademark) H” manufactured by Ashland, SP value 28.5, molecular weight 1.15 million) instead of CMC as the polysaccharide, the same procedure as in Example 1 was carried out. The coating material of Example 7 was prepared. The paint of Example 7 is included in the concept of the paint for heat insulating material of the present invention.
• HPC hydroxypropylcellulose
• SP value 28.5 molecular weight 1.15 million
• Comparative Example 1 Instead of polysaccharide, 9.89% by mass of thickener 1 (nonionic synthetic associative thickener: "Aquaflow (registered trademark) XLS-530" manufactured by Ashland, SP value 19.5) was added. A coating material of Comparative Example 1 was prepared in the same manner as in Example 1 except for the above points.
• thickener 1 nonionic synthetic associative thickener: "Aquaflow (registered trademark) XLS-530" manufactured by Ashland, SP value 19.5
• Comparative Example 2 instead of polysaccharides, 9.89% by mass of thickener 2 (nonionic synthetic associative thickener: “Aquaflow (registered trademark) NHS-350” manufactured by Ashland, SP value 20.1) was added. A coating material of Comparative Example 2 was prepared in the same manner as in Example 1 except for the above points.
• the thickener 2 is a thickener that forms a network by associating with a hydrophobic component. For this reason, the viscosity does not increase much when used alone, but increases when hydrophobic particles are added.
• Comparative Example 3 A coating material of Comparative Example 3 was prepared in the same manner as in Example 1, except that 2.67% by mass of polyvinylpyrrolidone (PVP: SP value: 36.4, molecular weight: 2,000,000) was added instead of the polysaccharide.
• PVP polyvinylpyrrolidone
• the prepared paint was blade-coated on a polyethylene terephthalate (PET) film.
• PET polyethylene terephthalate
• good coating properties were obtained (indicated by a mark “ ⁇ ” in Table 1 below), but coating was possible, but there were some problems such as uneven thickness. If there was, the coatability was normal (indicated by the symbol ⁇ in the table), and if the coating could not be applied due to repelling or solid separation, the coatability was poor (indicated by the mark x in the table). evaluated.
• Silica airgel was added to an aqueous solution in which additives (polysaccharides in Examples 1 to 7, and thickener 1, thickener 2, and PVP in Comparative Examples 1 to 3) were sequentially dissolved in water, followed by stirring.
• additives polysaccharides in Examples 1 to 7, and thickener 1, thickener 2, and PVP in Comparative Examples 1 to 3
• the silica aerogel did not settle, there was no intrusion into the pores (indicated by a triangle in Table 1 below), and when the silica aerogel settled, there was intrusion into the pores (the crosses in the same table). ).
• the prepared paint was applied to a substrate and dried to produce a heat insulating material, and the heat insulating property, cracks in the coating film and the presence or absence of silica airgel were evaluated.
• a sample for evaluation of heat insulation was produced as follows. First, the prepared paint was blade-coated on both sides of a non-woven fabric (manufactured by Kurashiki Fiber Processing Co., Ltd., thickness 5 mm, basis weight 130 g / m 2 ), and dried at 100 ° C. for 1 hour. At the time of blade coating, care was taken not to form an air layer inside the nonwoven fabric. Two nonwoven fabrics each having a coating film formed on both surfaces in this way were prepared, and the same coating material was overlaid on each surface and blade-coded, and then the one surfaces were bonded to each other. Then, a weight of 1 kg was placed on the two nonwoven fabrics that were superimposed, and dried at 100 ° C.
• thermo conductivity of the manufactured sample was measured using a heat flux meter “HC-074” manufactured by Eiko Seiki Co., Ltd., which complies with the heat flow meter method of JIS A1412-2 (1999).
• the coating film of the manufactured sample was visually observed to check for cracks.
• Table 1 the case where there was no crack is indicated by a mark, and the case where there is no crack is indicated by a cross.
• a weak adhesive tape (“Scotch (registered trademark) peelable tape” (product number: 811-3-12) manufactured by 3M) was applied to the coating film of the sample, and when the tape was peeled off, silica airgel was applied. It was examined whether or not it adhered. In the case where the silica airgel did not adhere, there was no detachment (indicated by the symbol “ ⁇ ” in Table 1 below). In the case where the test was performed, it was evaluated that the sample dropped out (indicated by a cross in the same table).
• Table 1 shows the content of each component in the prepared coating material, the evaluation result of the coating material, and the evaluation result of the heat insulating material.
• the content of the silica airgel in the coating film of the sample used for the evaluation of the heat insulating material is as follows (the entire coating film is 100% by mass). Examples 1, 4, 6, 7: 72.2% by mass, Example 2: 72.8% by mass, Examples 3, 5: 71.7% by mass, Comparative Examples 1, 2: 46.3% by mass, Comparative Example 3: 64.3% by mass.
• thermo conductivity of air at 40 ° C. is 0.0272 W / m ⁇ K or less. Therefore, it is understood that the samples using the paints of Examples 1 to 7 have higher heat insulating properties than the air.
• xanthan gum has a short main chain and side chains, so that the entanglement of molecular chains is reduced and the retention of silica airgel is reduced.
• the silica airgel was often dropped and cracked. It is considered that the reason for this is that HEC and HPC have large molecular weights, because the side chains are long, and the retention of silica airgel is reduced due to less entanglement of the main chain as compared with CMC.
• the heat insulating material of the present invention is suitable for heat insulating interior materials for automobiles, heat insulating materials for houses, heat insulating materials for home appliances, heat insulating materials for electronic components, heat insulating materials for heat insulation and cooling containers, and the like.

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• 2018
  • 2018-08-24 JP JP2018156903A patent/JP6836556B2/ja active Active
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