JP6446829B2 - Infrared shielding material, coating composition, and infrared shielding film - Google Patents

Description

  The present invention relates to an infrared shielding material, a coating composition using the same, and an infrared heat shielding film.

  In recent years, interest in energy conservation has increased and has attracted attention in various fields. Especially in Japanese houses and buildings, energy consumption by air conditioning is high. An infrared shielding film is known as a method for suppressing energy consumption by air conditioning.

  Sunlight can be classified into the ultraviolet region, visible light region, and infrared region. Of these, the infrared region is also called heat rays, and the absorbed light changes into heat in a wavelength region that is easily absorbed by all substances. . Therefore, infrared rays can be selectively shielded from direct sunlight by applying an infrared shielding film to a window, and an increase in indoor temperature can be suppressed. This leads to a reduction in heating and cooling costs and an energy saving effect.

  For example, Patent Document 1 includes at least an alkaline earth metal element and at least one element selected from titanium, zirconium, and niobium, and a periodic table of manganese and / or iron elements, aluminum, gallium, and the like as necessary. An infrared reflecting material of a perovskite complex oxide containing a group IIIa element, a zinc element or the like is disclosed. However, in Patent Document 1, it is difficult to improve dispersibility when an infrared reflective material is used as a coating liquid.

  For example, Patent Document 2 discloses an infrared shielding film having at least one unit formed by laminating a high refractive layer and a low refractive layer, each including a high refractive material and a low refractive material having different refractive indexes. Yes. In Patent Document 2, it is necessary to stack a plurality of layers for shielding infrared rays, and productivity is not good.

  For example, Patent Document 3 discloses a heat ray reflective layer made of a noble metal formed on a substrate by sputtering, and a metal mainly composed of aluminum or a metal mainly composed of aluminum and silicon formed on the heat ray reflective layer. The heat ray reflective plate which has visible light transmittance | permeability which has the coating layer which consists of oxynitride of this is disclosed. In Patent Document 3, a heat ray reflector is manufactured by a sputtering method, and there remains a problem in productivity, and the cost is high.

  For example, Patent Document 4 discloses an infrared reflective black pigment in which the surface of core particles made of cupric oxide is coated with a surface treatment agent, and the coating layer has acid resistance. Disclosure. Patent Document 4 is a black pigment, and is not suitable for cases where transparency is required, such as buildings and car windows.

  On the other hand, in recent years, functional materials using natural polymers, which are environmentally friendly materials that can be used continuously, have been actively developed in order to solve the problem of fossil resource depletion. However, Patent Documents 1 to 4 do not use environmentally conscious materials.

  Plant materials such as cellulose are known as environmentally friendly natural polymer materials having biodegradability. Cellulose, the main component of plants and wood, is a natural polymer material that is accumulated in large quantities on the earth. In wood, dozens or more of cellulose molecules are bundled to form fine fibers (microfibrils) having a high crystallinity and a nanometer order fiber diameter, and many fine fibers are hydrogen-bonded to each other. Cellulosic fibers are formed to become a plant support.

  There is known a method of using this cellulose fiber by making it fine (nanofiber) until the fiber diameter becomes nanometer order. Using an N-oxyl compound as an oxidation catalyst, a part of the hydroxyl group of cellulose is oxidized to at least one functional group selected from the group consisting of a carboxy group and an aldehyde group, and the maximum fiber diameter is 1000 nm or less and the number average fiber diameter is 2 A refined cellulose having a cellulose I-type crystal structure of 150 nm is known (Patent Document 5). As an example using fine cellulose, for example, as a packaging material having gas barrier properties such as oxygen, a packaging material containing at least fine cellulose, an inorganic layered compound and a water-soluble polymer on a substrate is also known (patent) Reference 6).

International Publication No. 2009/142254 International Publication No. 2013/077274 Japanese Patent Laid-Open No. 1-206035 International Publication No. 2010/073633 JP 2008-1728 A JP 2012-149114 A

  An object of the present invention is to provide an infrared shielding material that reduces environmental burden and has good dispersibility in a coating composition or a molding material, and a coating composition and an infrared shielding film using the same.

One aspect of the present invention for solving the above problems includes a composite in which flat metal fine particles and at least one or more refined celluloses are combined, and the flat metal fine particles include at least one kind of metal. Alternatively, each of the micronized celluloses has a minor axis number average axis diameter of 1 nm or more and 200 nm or less, a major axis number average axis diameter of 0.05 μm or more and 50 μm or less, and is entirely flat. Incorporated into the inside of the metal fine particles, or part is taken into the inside of the plate-like metal fine particles, and the rest is exposed on the surface of the plate-like metal fine particles, and has an absorption maximum in a wavelength region of 700 nm to 2500 nm. Infrared shielding material.

  In addition, the flat metal fine particles and the finely divided cellulose may be inseparable.

  Further, the flat metal fine particles may be silver.

  Moreover, 0.1 mmol / g or more and 3.0 mmol / g or less of the carboxy group amount of refined cellulose may be sufficient.

  Further, the thickness of the metal fine particles may be 1 nm or more and 100 nm or less.

  Another aspect of the present invention is a coating composition containing the above-described infrared shielding material.

  The coating composition further includes at least one or more types of water-soluble polymer (a), and the water-soluble polymer (a) contains 50 masses of any one of methanol, ethanol, propanol, and isopropyl alcohol at 85 ° C. It may be a compound having a molecular weight of 1000 or more, which dissolves 1 part by mass or more with respect to 100 parts by mass of a solvent containing at least one of water and an aqueous alcohol solution containing at least one kind.

  Another aspect of the present invention is an infrared shielding film including a substrate and a coating layer formed on at least one surface of the substrate, and the coating layer includes the above-described coating composition.

  Moreover, you may include at least 1 or more types of molding materials (b) and the above-mentioned infrared shielding material.

  Further, the substrate may be any of polyolefin, polyester, polyamide, polystyrene, ethylene vinyl alcohol, polyvinyl chloride, polyimide, polyvinyl alcohol, polycarbonate, polyethersulfone, and acrylic cellulose.

  The molding material (b) is polystyrene, ABS resin (A: acrylonitrile, B: butadiene, S: styrene), AS resin, polyethylene, EVA resin, polypropylene, methacrylic resin, cellulose acetate, polycarbonate, polyamide, polyacetal, polysulfone. , Polyethylene terephthalate, polybutylene terephthalate, or vinyl chloride resin.

  Further, the light transmittance may be 70% or less in a wavelength region of 900 nm to 1000 nm.

  Moreover, you may further contain the hard-coat layer laminated | stacked on the coating layer, and the adhesive layer formed in the surface on the opposite side to the surface in which the coating layer of the base material is formed. Alternatively, the molding material and the infrared shielding material may constitute a composite layer, and may further include a hard coat layer laminated on one surface of the composite layer and an adhesive layer formed on the other surface of the composite layer.

  INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide an infrared shielding material that reduces environmental burden and has good dispersibility in a coating composition or resin, and a coating composition and an infrared shielding film using the same.

It is sectional drawing of one Embodiment of the infrared shielding film which concerns on this invention. It is sectional drawing of one Embodiment of the infrared shielding film which concerns on this invention. It is a figure which shows typically the structure of the composite_body | complex which is one Embodiment to which this invention is applied. The observation result is shown with the scanning electron microscope (SEM) of the infrared shielding material of this invention, (a) is a SEM image, (B) is a schematic diagram of (A). The result which expanded and observed the infrared shielding material of this invention with the scanning transmission electron microscope (STEM) is shown, (A) is a STEM image, (B) is a schematic diagram of (A). The result which expanded and observed the infrared shielding material of this invention with the scanning electron microscope (SEM) is shown, (A) is a SEM image, (B) is a schematic diagram of (A). It is a figure (TEM image) which shows the result of having observed the infrared shielding material of this invention from the cross-sectional direction with the transmission electron microscope (TEM). It is a schematic diagram for demonstrating a part of process of the manufacturing method of the composite_body | complex which is one Embodiment to which this invention is applied.

  The technology disclosed herein relates to an infrared shielding material containing a natural polymer and metal fine particles, a coating composition using the infrared shielding material, and an infrared shielding thermal insulation film.

  In recent years, the use of environmentally conscious materials has been demanded while environmental problems are attracting attention. Moreover, it is a subject to manufacture an infrared shielding material and an infrared shielding film with low energy from a viewpoint of environmental impact. The infrared shielding material is desired to have good dispersibility when used as a coating composition or when it is combined with a molding material. Infrared shielding films are often used for buildings, car windows, and the like, and are required to be transparent, and long-term durability is important because of their usage.

  The present disclosure provides an infrared shielding material and an infrared shielding film that reduce environmental burden, have good dispersibility in a coating composition or a molding material, and have high durability.

  That is, flat metal fine particles and at least one or more refined celluloses are combined, and the flat metal fine particles are at least one kind of metal or a compound thereof, and each of the refined celluloses is at least partially. Alternatively, it is an infrared shielding material in which all is taken into the flat metal fine particles, and the remainder is exposed on the surface of the flat metal fine particles and has an absorption maximum in a wavelength region of 700 nm to 2500 nm.

  According to the present disclosure, there is provided an infrared shielding material that can be produced with low energy using a natural polymer having a low environmental load and is excellent in dispersibility, heat resistance, and light resistance. Furthermore, the present invention provides a coating composition having excellent coatability and forming a coating. Moreover, it is possible to shield infrared rays without laminating a plurality of layers, and an infrared shielding film can be manufactured at low cost with high productivity.

  1 and 2 are cross-sectional views of an embodiment of an infrared shielding film according to the present disclosure. In the infrared shielding film 1 shown in FIG. 1, a coating layer 12 containing an infrared shielding material is provided on one surface of a substrate 11, and a hard coat layer 13 is further provided on the surface of the coating layer 12 opposite to the substrate 11. An adhesive layer 14 is provided on the surface of the substrate 11 opposite to the coating layer 12.

The infrared shielding film 2 shown in FIG. 2 is provided with a hard coat layer 22 on one surface of a composite layer 21 of an infrared shielding material and a molding material, and a hard coat layer of a composite composition 21 of an infrared shielding material and a molding resin. An adhesive layer 23 is provided on the surface opposite to the surface 22.
(Infrared shielding material)
The infrared shielding material according to the present disclosure contains a natural polymer and metal fine particles, the natural polymer and the metal fine particles are physically inseparable, and has a characteristic of shielding light in a wavelength region of 700 nm or more. Specifically, it is preferable that the light transmittance in the wavelength region of 800 nm to 1000 nm is 70% or less. Since a natural polymer is used, environmental impact is low, and it can be manufactured without complicated processes. An infrared shielding material containing metal fine particles and a natural polymer is excellent in dispersibility, heat resistance, and light resistance.

  As shown in FIGS. 1 and 2, the composite composition 21 of the infrared shielding material and the molding material and the coating layer 12 containing the infrared shielding material can be used for the infrared shielding films 1 and 2 having an infrared shielding function. . Furthermore, the infrared shielding material according to the present disclosure is excellent in dispersibility in a solvent, and the coating composition containing this infrared shielding material is also excellent in coatability. In the present disclosure, shielding refers to a decrease in light transmittance due to absorption or reflection.

  FIG. 3 is a diagram schematically showing a configuration of an infrared shielding material which is an embodiment to which the present invention is applied. As shown in FIG. 3, the infrared shielding material 3 according to the present embodiment includes a plate-like metal fine particle 31 in which a plate-like metal fine particle 31 and at least one or more refined cellulose 32 are combined, and a finer structure. Is the composite with cellulose 32, and the flat metal fine particles 31 are at least one kind of metal or a compound thereof, and are all the finely divided celluloses 32 taken into the flat metal fine particles 31? , At least a part (a part) is taken into the inside of the plate-like metal fine particles 31 and the rest is exposed so as to be exposed on the surface of the metal fine particles 31.

  FIG. 4 shows the result of observing the infrared shielding material of the present invention with a scanning electron microscope (SEM), and (B) is a schematic diagram of (A). FIG. 5 shows the result of magnifying and observing the infrared shielding material of the present invention with a scanning transmission electron microscope (STEM), (A) is a STEM image, and (B) is a schematic diagram of (A). It is. FIG. 6: has shown the result of having expanded and observed the infrared shielding material of this invention with the scanning electron microscope (SEM), (A) is a SEM image, (B) is the schematic diagram of (A). It is.

  As shown in FIGS. 4, 5, and 6, each refined cellulose 32 includes a portion 32 a that is taken into the interior of the metal microparticle 31 and a portion 32 b that is exposed on the surface of the metal microparticle 31. Has been.

  Then, due to the presence of the taken-in portion 32a, the metal fine particles 31 and the respective refined cellulose 32 are inseparable. That is, at least a part of the fine metal particles 31 and the fine cellulose 32 are physically bonded to each other when at least a part (that is, the part 32 a) of the fine cellulose 32 is taken into the flat metal fine particles 31. Therefore, it is preferable to be in an indivisible state.

  Here, in the infrared shielding material 3 of the present embodiment, at least a part of the micronized cellulose 32 (that is, the part 32a) is taken into the inside of the metal fine particles 31 as described in the manufacturing method described later. In the growth stage of the fine particles 31, this is synonymous with the state in which the fine cellulose is sandwiched along the grain boundary of the metal fine particle unit.

  Moreover, in the infrared shielding material 3 of this embodiment, the state in which both the metal fine particles 31 and the fine cellulose 32 are “indivisible” means that the metal fine particles 31 and the fine cellulose are obtained by a physical method such as a centrifuge. This means that it cannot be separated into 32. Since the metal fine particles 31 and the refined cellulose 32 are inseparable, the dispersion stability is increased.

  In addition, the infrared shielding material 3 has a configuration in which the entire portion (the whole) of all the refined cellulose 32 constituting the infrared shielding material 3 is taken into the metal fine particles 31 and there is no portion exposed on the surface of the metal fine particles 31. Is included in the scope of the present invention as long as the presence of the incorporated portion 32a can be confirmed.

  The observation of the complex can be performed by the following method. The composite is purified by a high-speed cooling centrifuge, cast on a silicon wafer plate, subjected to platinum vapor deposition, and then observed from the vertical direction using a scanning electron microscope (S-4800, manufactured by Hitachi High-Tech). Thus, as shown in FIGS. 4 and 6, it is possible to observe the flat metal fine particles 31 and the refined cellulose 32 b exposed on the surface. Further, by observing with a scanning transmission electron microscope as shown in FIG. 5, it is possible to confirm the refined cellulose 32 a taken into the flat metal fine particles 31. In addition, the composite was cast on a silicon wafer plate, observed with a scanning electron microscope without vapor deposition, and then element mapping was performed by energy dispersive X-ray analysis, and the composite was detected by detection of carbon with metal and refined cellulose. Can be confirmed.

  Moreover, the manufacturing method of the said infrared shielding material is although it does not specifically limit, It can manufacture by reduce | restoring a precursor metal ion in presence of refined | miniaturized cellulose. Precursor metal ions are reduced to form metal atoms, and in the process of forming metal fine particles through nucleation and growth, metal fine particles interact with finely divided cellulose, affecting the shape and aggregation of metal fine particles. It is considered that the fine particles and the finely divided cellulose are combined. In the composite formed in such a process, at least a part or all of each of the fine cellulose is taken into the metal fine particles, and the remaining part is exposed on the surface of the metal fine particles. In the infrared shielding material of the present invention, the metal fine particles and the refined cellulose are preferably inseparable from the viewpoint of dispersion stability.

  The infrared shielding material according to the present disclosure has an absorption maximum in a wavelength region of 700 nm to 2500 nm. The infrared ray shielding composition or infrared ray shielding film of the present invention can prevent infrared rays from being transmitted, that is, can block infrared rays, by absorbing infrared rays or reflecting them by re-radiation by an infrared ray shielding material.

  The absorption maximum can be evaluated by measuring the transmittance or absorbance of a dispersion containing an infrared shielding material using a spectrophotometer. Using a cell having an optical path length of 1 cm, a wavelength region of 220 nm to 2500 nm is measured using a dispersion medium as a reference. When measuring the transmittance, it is preferable that the transmittance of light in the wavelength region of 900 nm to 1000 nm is 70% or less. Since the refined cellulose is used, the environmental load is low, and it can be produced without including complicated processes. The infrared shielding material according to the present invention is an infrared shielding material excellent in dispersibility, heat resistance, and light resistance.

  Free electrons on the metal surface may collectively vibrate due to an external electric field such as light (surface plasmon). Since electrons are charged particles, an electric field is generated around them when they vibrate. In the metal fine particles, an electric field generated by free electron vibration and an external electric field (light etc.) resonate (surface plasmon resonance (SPR)). The surface plasmon resonance causes light absorption in a specific wavelength range. This light absorption wavelength region varies depending on the size and shape of the particles.

  Since the resonance wavelength of the metal fine particles changes depending on the aspect ratio, it is considered that the resonance wavelength changes due to anisotropy when the metal fine particles and the natural polymer form a complex. In the infrared shielding material according to the present invention, the shape of the metal fine particles preferably has an anisotropy such as a flat plate shape or a rod shape in order to shield light in a wavelength region of 700 nm or more. In particular, a plate-like composite is preferable because of easy shape control. The shape of the infrared shielding material according to the present invention is observed with a scanning electron microscope, a transmission electron microscope, and a scanning transmission electron microscope. The infrared shielding material according to the present disclosure contains finely divided cellulose and metal fine particles, and the finely divided cellulose and metal fine particles may be physically inseparable, and may contain other components as necessary.

  In the present embodiment, the term “flat plate” refers to plate-like particles. When the area of the front surface 33 or the back surface 34 is a particle diameter d corresponding to a circle, the average aspect obtained by dividing the particle diameter d by the particle thickness h. It means particles having a ratio (d / h) of 2.0 or more. In addition, although the shape of the surface 33 and the back surface 34 is not specifically limited, Usually, they are polygons, such as a hexagon and a triangle. The front surface 33 and the back surface 34 are not particularly limited, and the front surface 33 and the back surface 34 may be reversed, and either area may be large.

  In order to shield infrared rays, the particle size of the tabular metal fine particles 31 is preferably 20 nm or more and 500 nm or less, and more preferably 20 or more and 400 nm or less.

  The particle thickness of the flat metal fine particles 31 is preferably 1 nm or more and 100 nm or less, and more preferably 5 nm or more and 50 nm or less.

  The average aspect ratio (d / h) is preferably 2.0 or more, more preferably 2.0 or more and 100 or less, and still more preferably 2.0 or more and 50 or less.

  The shape and size of the infrared shielding material according to the present disclosure can be evaluated using a scanning electron microscope, a transmission electron microscope, and a scanning transmission electron microscope.

When the infrared shielding material is flat, specific examples of the method for measuring the particle diameter and thickness of the metal fine particles and the method for calculating the aspect ratio include the following methods.
(1) Measuring method of particle diameter A dispersion containing an infrared shielding material is cast on a copper grid with a support film for TEM observation and air-dried, and then observed with a transmission electron microscope. The diameter when the metal fine particles in the obtained image are approximated by a circle is calculated as the particle diameter in the plane direction.
(2) Thickness measurement method FIG. 7 shows the result of cross-sectional observation of a flat infrared shielding material for the purpose of measuring thickness. The thickness was measured by the following method. A dispersion containing an infrared shielding material is cast on a PET film, air-dried and fixed with an embedding resin, cut in a cross-sectional direction with a microtome, and observed with a transmission electron microscope. The thickness of the tabular silver fine particles in the obtained image is calculated as the particle diameter in the plane direction.
(3) Aspect Ratio Calculation Method When the particle diameter obtained as described above is d and the particle thickness is h, the value obtained by dividing the particle diameter d by the particle thickness h is the aspect ratio = d / h. calculate.

The measurement method and the calculation method described above are examples, and are not particularly limited to these.
(Natural polymer)
Natural polymers used in the infrared shielding material according to the present disclosure are polymers produced by animals, plants, and microorganisms. Natural polymers are generally known as polysaccharides and polypeptides. Examples of the polysaccharide include starch, cellulose, chitin / chitosan, cellulose, dextran, pullulan, curdlan, alginic acid, and hyaluronic acid. Examples of the polypeptide include gluten, zein, collagen, gelatin, fibroin, sericin, keratin and the like.

  Especially, it is preferable to use the refined cellulose refined | miniaturized by the method shown below. By using micronized cellulose, an infrared shielding material containing a natural polymer and metal fine particles can be efficiently produced with low energy, and the dispersibility in a solvent is particularly good.

The refined cellulose used in the infrared shielding material according to the present disclosure may have at least one side of its structure on the order of nanometers, and the preparation method is not particularly limited. Usually, since the refined cellulose takes a fiber shape derived from a microfibril structure, the refined cellulose used in the production method of the present embodiment is preferably a fiber shaped product in the following range. That is, the refined cellulose is preferably a refined cellulose of fibers.
(Micronized cellulose and its production method)
The refined cellulose used in the infrared shielding material according to the present disclosure is not particularly limited, but the shaft diameter is preferably within the range shown below. Moreover, the preparation method is not particularly limited. That is, the number average minor axis diameter is preferably 1 nm or more and 200 nm or less, more preferably 1 nm or more and 50 nm or less. If the number average minor axis diameter is less than 1 nm, a highly crystalline rigid refined cellulose structure cannot be obtained. On the other hand, when it exceeds 100 nm, the viscosity becomes high, workability is poor, and it becomes difficult to produce an infrared shielding material. As for the major axis diameter, the number average major axis diameter is preferably 0.05 μm or more and 50 μm or less, and more preferably 0.1 μm or more and 10 μm or less. When the number average major axis diameter of the major axis diameter is within this range, it is easy to produce an infrared shielding material. If the number average shaft diameter is smaller than 0.05 μm, it is difficult to produce an infrared shielding material. Moreover, when it exceeds 50 micrometers, a viscosity will be high and workability | operativity will worsen.

  The number average minor axis diameter of the refined cellulose is obtained as an average value obtained by measuring the minor axis diameter (minimum diameter) of 100 fibers by observation with a transmission electron microscope and observation with an atomic force microscope. On the other hand, the number average major axis diameter of the refined cellulose is obtained as an average value obtained by measuring the major axis diameter (maximum diameter) of 100 fibers by observation with a transmission electron microscope and observation with an atomic force microscope.

  The kind of plant cellulose that can be used as a raw material for the refined cellulose is not particularly limited. For example, in addition to wood-based natural cellulose, cotton linter, bamboo, hemp, bagasse, and kenaf can be used. Further, non-wood type natural cellulose such as bacterial cellulose, squirt cellulose, and valonia cellulose, and regenerated cellulose represented by rayon fiber and cupra fiber can also be used.

The method for refining cellulose fibers is not particularly limited. For example, in addition to mechanical treatment by a grinder, oxidation treatment using N-oxyl compounds such as TEMPO, dilute acid hydrolysis treatment, enzyme treatment, etc. are used in combination with mechanical treatment. A method for miniaturization is known. Bacterial cellulose can also be used as refined cellulose. Furthermore, finely regenerated cellulose fibers obtained by dissolving various natural celluloses in various cellulose solvents and then performing electrospinning may be used. In particular, as shown in the method of Patent Document 5, in the oxidation reaction using an N-oxyl compound such as TEMPO, the —CH ₂ OH at the 6th position of the glucopyranose unit of the cellulose molecular chain on the crystal surface is high. It is oxidized selectively and converted to a carboxy group via an aldehyde group. In this way, electrostatic repulsion acts between the refined cellulose having carboxy groups introduced on the crystal surface, so that cellulose single nanofibers (CSNF) dispersed in microfibril units in an aqueous medium can be obtained. Can do. The oxidation reaction using the N-oxyl compound will be described in detail later. If this refined cellulose is used, the shape of the metal fine particles can be sufficiently controlled.

  The content of carboxy groups in the refined cellulose is preferably in the range of 0.1 mmol to 3.0 mmol, more preferably 0.5 mmol to 3.0 mmol, per gram of refined cellulose. When the carboxy group amount is 0.1 mmol / g or more, the dispersion stability is good. When it is 3.0 mmol / g or less, the crystal structure of the fine cellulose is sufficiently retained, and an infrared shielding material can be easily produced.

Hereinafter, an example of a method for preparing a dispersion of fine cellulose having a carboxy group introduced by an oxidation reaction using an N-oxyl compound from wood-based natural cellulose will be described. The preparation method of this example includes a step (oxidation step) in which wood-based natural cellulose is oxidized using an N-oxyl compound to obtain oxidized cellulose, and the oxidized cellulose is refined in an aqueous medium to obtain a refined cellulose dispersion. And a step of preparing (miniaturization step).
(Oxidation process)
The raw material of the fine cellulose is not particularly limited, and when wood cellulose is used, commonly used materials such as softwood pulp, hardwood pulp, and waste paper pulp can be used. Softwood pulp is preferred because it is easily refined and refined. Examples of N-oxyl compounds include TEMPO (2,2,6,6-tetramethylpiperidinyl-1-oxy radical), 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, 4 -Methoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamido-2,2,6,6 -Tetramethylpiperidine-N-oxyl, etc. Among these, TEMPO is preferable. The amount of the N-oxyl compound used is not particularly limited, and may be an amount as a catalyst. Usually, it is about 0.01% by mass or more and 5.0% by mass or less with respect to the solid content of the wood-based natural cellulose to be oxidized.

  Examples of the oxidation method using an N-oxyl compound include a method in which a cellulose raw material is dispersed in water and oxidized in the presence of the N-oxyl compound. At this time, it is preferable to use a co-oxidant together with the N-oxyl compound. In this case, in the reaction system, the N-oxyl compound is sequentially oxidized by the cooxidant to produce an oxoammonium salt, and the cellulose is oxidized by the oxoammonium salt. According to such oxidation treatment, the oxidation reaction proceeds smoothly even under mild conditions, and the introduction efficiency of the carboxy group is improved. When the oxidation treatment is performed under mild conditions, it is easy to maintain the crystal structure of cellulose. Co-oxidants include halogens, hypohalous acids, halous acids and perhalogen acids, or salts thereof, halogen oxides, nitrogen oxides, peroxides, etc., as long as they can promote the oxidation reaction. Any oxidizing agent can be used. Sodium hypochlorite is preferred because of its availability and reactivity. The amount of the co-oxidant used is not particularly limited, and may be an amount that can promote the oxidation reaction. Usually, it is about 1 mass% or more and 200 mass% or less with respect to the solid content of the cellulose to oxidize.

  Along with the N-oxyl compound and the co-oxidant, at least one compound selected from bromide and iodide may be further used in combination. Thereby, an oxidation reaction can be advanced smoothly and the introduction efficiency of a carboxy group can be improved. As the compound, sodium bromide or lithium bromide is preferable, and sodium bromide is more preferable from the viewpoint of cost and stability. The amount of the compound used is not particularly limited, and may be an amount that can promote the oxidation reaction. Usually, it is about 1 to 50% by mass relative to the solid content of wood-based natural cellulose to be oxidized.

  The reaction temperature of the oxidation reaction is preferably 4 ° C. or higher and 50 ° C. or lower, and more preferably 10 ° C. or higher and 50 ° C. or lower. If it is lower than 4 ° C., the reactivity of the reagent is lowered and the reaction time is prolonged. If the temperature exceeds 50 ° C., the side reaction is promoted to lower the molecular weight of the sample, and the fiber shape cannot be maintained. The reaction time of the oxidation treatment can be appropriately set in consideration of the reaction temperature, the desired amount of carboxy group, and the like, and is not particularly limited, but is usually about 1 hour to 5 hours.

  The pH of the reaction system during the oxidation reaction is preferably 9 or more and 11 or less. When the pH is 9 or more, the reaction can be efficiently carried out. If the pH exceeds 11, side reactions may progress and the decomposition of the sample may be accelerated. In the oxidation treatment, as the oxidation proceeds, the pH in the system decreases due to the formation of a carboxy group. Therefore, it is preferable to maintain the pH of the reaction system at 9 or more and 11 or less during the oxidation treatment. Examples of a method for maintaining the pH of the reaction system at 9 or more and 11 or less include a method of adding an alkaline aqueous solution in accordance with a decrease in pH. Examples of alkaline aqueous solutions include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, tetrabutylammonium hydroxide aqueous solution, and benzyltrimethylammonium hydroxide aqueous solution. And organic alkalis. A sodium hydroxide aqueous solution is preferable from the viewpoint of cost.

  The oxidation reaction with the N-oxyl compound can be stopped by adding alcohol to the reaction system. At this time, the pH of the reaction system is preferably maintained within the above-mentioned range. The alcohol to be added is preferably a low molecular weight alcohol such as methanol, ethanol or propanol in order to quickly terminate the reaction, and ethanol is particularly preferred from the viewpoint of safety of by-products generated by the reaction.

The reaction solution after the oxidation treatment may be directly subjected to a refinement process, but in order to remove a catalyst such as an N-oxyl compound, impurities, etc., the oxidized cellulose contained in the reaction solution is recovered and washed with a washing solution. It is preferable. Oxidized cellulose can be collected by a known method such as filtration using a glass filter or a nylon mesh having a 20 μm pore size. Distilled water is preferable as the cleaning liquid used for cleaning the oxidized cellulose.
(Miniaturization process)
In order to refine the oxidized cellulose, first, an aqueous medium is added to the oxidized cellulose and suspended. Examples of the aqueous medium include those described above, and water is particularly preferable. If necessary, the pH of the suspension may be adjusted in order to increase the dispersibility of the oxidized cellulose and the fine cellulose to be produced. Examples of the alkaline aqueous solution used for pH adjustment include the same alkaline aqueous solution as mentioned in the description of the oxidation step.

  Subsequently, the suspension is subjected to a physical defibrating treatment to refine the oxidized cellulose. For physical fibrillation treatment, high pressure homogenizer, ultra high pressure homogenizer, ball mill, roll mill, cutter mill, planetary mill, jet mill, attritor, grinder, juicer mixer, homomixer, ultrasonic homogenizer, nanogenizer, underwater facing collision, etc. Mechanical treatment is mentioned. By performing such physical fibrillation treatment, the oxidized cellulose in the suspension is refined, and a dispersion of refined cellulose having a carboxy group on the fiber surface can be obtained. The number average minor axis diameter and number average major axis diameter of the refined cellulose contained in the obtained refined cellulose dispersion can be adjusted by the time and number of times of physical fibrillation treatment at this time.

  As described above, a dispersion of fine cellulose having a carboxy group introduced therein is obtained. The obtained dispersion can be used as a reaction field for reducing and precipitating metal fine particles as it is or by diluting, concentrating and the like.

The finely divided cellulose dispersion may contain cellulose and components other than the components used for pH adjustment, as long as the effects of the present disclosure are not impaired. Other components are not particularly limited, and can be appropriately selected from known additives depending on the application. Specifically, organometallic compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic needle minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants, antistatic agents, An ultraviolet absorber, a stabilizer, magnetic powder, etc. are mentioned.
(metal)
The metal fine particles can absorb light of any wavelength ranging from visible light to near infrared light by shape control, and have light selectivity by absorbing in a desired wavelength region according to the use of various compositions. The metal species to be combined with the natural polymer is not particularly limited, gold, silver, copper, aluminum, iron, platinum, zinc, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, Examples thereof include metals such as manganese, vanadium, molybdenum, gallium, and aluminum, metal salts, metal complexes, alloys thereof, oxides, and double oxides. In particular, for the purpose of shielding infrared rays, at least one kind containing at least silver is preferable.

The deposited metal fine particles 31 may be coated with another metal or metal oxide to improve the stability of the metal fine particles. Similarly, the micronized cellulose 32 may be covered with another metal or metal oxide. The metal species used for the coating is not particularly limited, for example, gold, silver, copper, aluminum, iron, platinum, zinc, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, manganese, vanadium, molybdenum, Examples include metals such as gallium and aluminum, metal salts, metal complexes, and alloys thereof, or oxides and double oxides.
(Production method of infrared shielding material)
The method for producing the infrared shielding material is not particularly limited, but can be prepared by a liquid phase reduction method which is a general wet method. The surface of the metal fine particles and the solvent do not have a strong affinity, and the particles will aggregate and precipitate as they are. Due to the presence of the natural polymer, the characteristics of the metal fine particles are greatly changed.

  Although an infrared shielding material is not specifically limited, For example, it can manufacture with the following method. First, a finely divided cellulose dispersion and a solution containing a metal salt are mixed to obtain a mixing solution. Specifically, a metal salt is dissolved in a solvent to prepare a solution containing precursor metal ions. Next, the precursor metal ion-containing solution is added to the fine cellulose dispersion and mixed. Subsequently, the precursor metal ions in the mixed solution are reduced to grow metal fine particles, and the metal fine particles and fine cellulose are combined. FIG. 8 shows how the primary particles 31a of the metal fine particles grow and form a composite with the refined cellulose 32.

  By adding a reducing agent in the presence of natural polymers such as finely divided cellulose and precursor metal ions, the precursor metal ions are reduced to form metal atoms, and nucleation and growth generate metal fine particles. . In this process, it is considered that the metal fine particles and finely divided cellulose interact to affect the shape and aggregation of the metal fine particles. Due to the interaction between the natural polymer and the precursor metal ion, anisotropic metal fine particles are generated and photoselectivity is generated. For example, spherical silver fine particles usually have absorption in the vicinity of 400 nm, but become anisotropic particles when combined with fine cellulose, and have absorption in a wavelength region of 700 nm or more.

  In particular, in the case of micronized cellulose having a carboxy group on the surface, metal fine particles and micronized cellulose are compounded from the carboxy group as a starting point by reducing metal ions coordinated to the carboxy group. It is considered that the crystal growth and aggregation of the fine particles are controlled, and the morphology is controlled.

  The solvent used for dispersion of the fine cellulose is not particularly limited as long as the fine cellulose is sufficiently dispersed or dissolved. It is preferable to use water from the viewpoint of environmental load. When using micronized cellulose, it is preferable to use water or a hydrophilic solvent from the viewpoint of dispersibility. Although there is no restriction | limiting in particular about a hydrophilic solvent, Alcohols, such as methanol, ethanol, isopropanol, are preferable.

  The concentration of the fine cellulose dispersion used for the preparation is not particularly limited, but is preferably 0.1% or more and less than 50%. If it is less than 0.1%, the shape control effect of the metal fine particles is insufficient, and if it is 50% or more, the viscosity increases rapidly and workability deteriorates. The concentration of the precursor metal ion added to the dispersion of the natural polymer is not limited. The precursor metal ion concentration and the solid content concentration of the refined cellulose affect the shape and size of the infrared shielding material to be produced, and further the optical characteristics. The optical selectivity of the infrared shielding material varies greatly depending on its shape. The specific method for producing the infrared shielding material is described in detail in the examples.

  The precursor metal ion is not particularly limited, and a commonly used precursor metal ion such as chloroauric acid, silver nitrate, silver cyanide, and silver acetate can be used. When using a precursor silver ion source, it is preferable to use silver nitrate from the viewpoint of safety.

  The concentration of the precursor metal ion is not particularly limited. Depending on the precursor metal ion concentration, the interaction between the metal fine particles and the refined cellulose, and further the crystal growth and aggregation of the metal fine particles can be controlled, and the metal fine particles having a desired shape can be produced.

  It is preferable that the amount of precursor metal ions in the dispersion is less than the carboxy group present on the surface of the refined cellulose. When the amount of metal ions in the dispersion exceeds the amount of carboxy groups present on the surface of the refined cellulose, the refined cellulose may aggregate.

A known method can be used for the reduction of the precursor metal ion. For example, a method of irradiating ultraviolet rays or a reducing agent can be added. In the case of adding a reducing agent, the reducing agent can be dissolved in a solvent in advance and added dropwise to a dispersion (hereinafter referred to as a reaction system) containing precursor metal ions and refined cellulose.
(Reducing agent)
A known reducing agent can be used as the reducing agent used for reducing the precursor metal ion. Examples thereof include metal hydride-based, borohydride-based, borane-based, silane-based, hydrazine, and hydrazide-based reducing agents. In general, sodium borohydride, citric acid, hydrazine and the like are used in the liquid phase reduction method. It is preferable to stir by a known method such as a stirring blade or a stirring bar.
(Coating composition, coating, infrared shielding film)
The infrared shielding material is separated from the dispersion of the infrared shielding material thus obtained, and is not particularly limited, but can be applied to windows as a coating composition for forming a coating. The infrared shielding film 1 can be obtained by applying the coating composition to at least one surface of the substrate 11 and providing the coating layer 12 containing an infrared shielding material. Further, the infrared shielding film 2 can be obtained by combining an infrared shielding material with a molding material. The infrared shielding films 1 and 2 preferably have a light transmittance of 70% or less in a wavelength region of 900 nm or more and 1000 nm or less.

  When using an infrared shielding material for a coating composition or an infrared shielding film coated with the same, it is preferable to fractionate the infrared shielding material from a dispersion of the infrared shielding material. As a method for fractionating the infrared shielding material, a known method such as precipitation, centrifugation, gel filtration column, gel electrophoresis or the like can be used. A plurality of fractionation methods may be combined.

  As a method for redispersing the infrared shielding material, a known method can be used. Examples thereof include a dispersion device in liquid such as a stirring type disperser, a high speed rotary shearing device, a mill type dispersing device (ball mill, bead mill, colloid mill, etc.), a high pressure jet device, and an ultrasonic dispersing device. You may disperse | distribute by adding a dispersing agent.

  Although it does not specifically limit when obtaining a coating composition and the coating material which apply | coated this, or the infrared shielding film 1, Although it does not specifically limit, an infrared shielding material can be fractionated and used from the dispersion liquid of an infrared shielding material.

  The coating composition is not particularly limited as long as it can form a film on the substrate 11. The coating composition preferably contains an infrared shielding material and at least one water-soluble polymer (a). By using the water-soluble polymer (a), it is possible to obtain a coating composition having good dispersibility of the infrared shielding material and good coatability, and obtaining high infrared shielding properties without laminating a plurality of layers. In other words, it is possible to obtain a coating or an infrared shielding film 1 having excellent light resistance. Further, the adhesion with the substrate 11 is improved.

  The water-soluble polymer (a) is 85 ° C. with respect to 100 parts by mass of an aqueous alcohol solution containing 50% by mass of any one of methanol, ethanol, propanol and isopropyl alcohol, and 100 parts by mass of a solvent containing at least one of water. It is a compound having a molecular weight of 1000 or more that dissolves by mass parts or more. In the present disclosure, the term “dissolving of a compound” includes not only a dissolved state in which the compound is completely molecularly dispersed, but also that the compound is swollen and dispersed to show a uniform dissolved state. That is, an alcohol aqueous solution containing 50% by mass of methanol, ethanol, propanol, or isopropyl alcohol, and an emulsion that is dispersed in an amount of 1 part by mass or more with respect to 100 parts by mass of a solvent containing at least one of water.

  Examples of the water-soluble polymer (a) include protein, vinyl resin, acrylic resin, polyethylene, urethane resin, and epoxy resin.

  Examples of proteins include gelatin, casein, and sodium chondroitin sulfate.

  Examples of the vinyl resin include polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl pyrrolidone / vinyl acetate copolymer.

  Examples of the acrylic resin include sodium polyacrylate, carboxyvinyl polymer, polyacrylamide, and acrylamide / acrylate copolymer.

  Examples of the polyethylene resin include polyethyleneimine, polyethylene oxide, polyethylene glycol, and the like.

  Among these, vinyl resins and polyethylene resins are preferable because the infrared shielding material is easily dispersed. As the water-soluble polymer (a), only one type may be used, or two or more types may be used. Further, from the viewpoint of environmental load, it is desirable that the polymer is a naturally derived polymer.

  Although the solvent of a coating composition is not specifically limited, It is preferable to use water and a hydrophilic solvent from a dispersible viewpoint. Although there is no restriction | limiting in particular about a hydrophilic solvent, Alcohols, such as methanol, ethanol, isopropanol, are preferable. Of these, water and ethanol are preferable.

  The coating layer 12 formed by the coating composition includes an infrared shielding material. As a method for forming the coating layer 12, known methods such as room temperature dry coating, heat-curing coating, and electrodeposition coating can be used. Although the film thickness of the coating layer 12 is not specifically limited, It is preferable that it is the range of 1 nm or more and 10000 nm or less. When it is 5 nm or more, the coating property of the coating composition containing the infrared shielding material is good. If it is 10,000 nm or more, it takes time to dry, and the adhesion between the substrate 11 and the coating layer 12 may deteriorate.

  Although the material of the base material 11 which forms the coating layer 12 is not specifically limited, A well-known plastic material can be used. In the infrared shielding application for windows, a transparent substrate is preferable.

  Examples of the material of the substrate 11 include polyolefin (polyethylene, polypropylene, etc.), polyester (polyethylene naphthalate, polyethylene terephthalate, etc.), polyamide (nylon-6, nylon-66, etc.), polystyrene, ethylene vinyl alcohol, Polyvinyl chloride, polyimide, polyvinyl alcohol, polycarbonate, polyether sulfone, acrylic cellulose (triacetylyl cellulose, diacetyl cellulose, etc.) and the like can be mentioned.

  Although the film thickness of the base material 11 is not specifically limited, From the viewpoint of productivity, moldability, and operability during construction, the thickness of the base material 11 is preferably 5 μm or more and 1000 μm or less, and is 10 μm or more and 500 μm or less. Is more preferable.

  The surface of the substrate 11 on the side where the coating layer 12 is provided may be subjected to surface treatment, and a surface treatment layer may be provided as necessary. By performing the surface treatment, it is easy to perform coating on the base material, and adhesion between the base material 11 and the coating layer 12 can be improved. Examples of the surface treatment include corona treatment and plasma treatment.

  An adhesive layer may be provided for the purpose of improving the adhesion between the substrate 11 and the coating layer 12. Examples of the adhesive component used for forming the adhesive layer include adhesion of phenol resin, urea resin, melamine resin, polyvinyl resin, polyolefin resin, urethane resin, epoxy resin, acrylic resin, polyester resin, polyamide resin, polystyrene resin, etc. Resin. Among these, as the adhesive resin, it is preferable to use a polyvinyl resin, a polyolefin resin, or an acrylic resin from the viewpoint of good adhesion.

  As the composite 21 of the infrared shielding material and the molding material, the infrared shielding film 2 can be manufactured. A known plastic material can be used as the molding material to be combined with the infrared shielding material.

  As the plastic material, generally used thermoplastic resins and thermosetting resins can be used. It is preferable to contain a molding material (b) from the viewpoint of ease of compounding with an infrared shielding material and molding.

  The molding material (b) includes polystyrene, ABS resin (A: acrylonitrile, B: butadiene, S: styrene), AS resin, polyethylene, EVA resin, polypropylene, methacrylic resin, cellulose acetate, polycarbonate, polyamide, polyacetal, polysulfone, Polyethylene terephthalate, polybutylene terephthalate, and vinyl chloride resin are preferred.

  In particular, it is preferable to use biomass plastics using renewable resources. As biomass plastics using renewable resources, it is preferable to use polylactic acid, polyolefin, or polyamide.

  A known method can be used as a composite method when combining the infrared shielding material and the molding material (b).

  A known method can be used as the molding method. For example, injection molding, compression molding, lamination molding, transfer molding, extrusion molding, inflation molding, T-die molding, extrusion lamination, blow molding, vacuum molding, splash molding, low pressure lamination molding Is mentioned.

  The structure of the infrared shielding films 1 and 2 is not particularly limited. For example, the coating layer containing the infrared shielding material may not be a single layer but may be provided with multiple layers. The composite layer 21 of the infrared shielding material and the molding material may have a laminated structure.

  The coating layer 12 containing the infrared shielding material and the composite layer 21 of the infrared shielding material and the molding material are mixed with known additives for the purpose of improving moldability, suppressing deterioration, and improving the dispersibility of the infrared shielding material. can do. For example, a heat stabilizer, a stabilizing aid, a plasticizer, an antioxidant, a light stabilizer, a flame retardant, a lubricant, and an antistatic agent may be included.

  In order to obtain scratch resistance, the coating layer 12 containing the infrared shielding material and the composite layer 21 of the infrared shielding material and the molding material are preferably provided with a hard coat layer 13 or a hard coat layer 22. Although a hard coat layer (13, 22) is not specifically limited, Thermosetting type or photocurable type resins, such as urethane resin, acrylic resin, silicone resin, a fluorine resin, are mentioned. Although it does not specifically limit, it is preferable that the thickness of a hard-coat layer is 0.5 micrometer or more and 100 micrometers or less. When the thickness of the hard coat layer is less than 0.5 μm, sufficient scratch resistance cannot be obtained, and when it is 100 μm or more, the transparency is liable to be lost, and the operability is deteriorated when being attached to a window.

  The adhesive layer 14 or the adhesive layer 23 is provided on the opposite surface of the coating layer 12 containing the infrared shielding material of the substrate 11 and the opposite surface of the composite layer 21 of the infrared shielding material and the molding material to the hard coat layer 22. Is preferred. The adhesive layer can be attached to, for example, a building or a car window. The material used for the adhesive layer is not particularly limited. For example, a known resin can be used, and examples thereof include a urethane resin, an acrylic resin, a polyester resin, and a silicone resin. One or more of these can be used. The method for forming the adhesive layer is not particularly limited, but the adhesive layer can be formed by a known coating technique. For example, the support layer can be coated with the adhesive layer 14 and bonded to the surface of the substrate 11 opposite to the coating layer 12. Even when the composite layer 21 of the infrared shielding material and the molding material is used, it can be bonded after the support layer is coated with the adhesive layer 23. As a bonding method, a known method such as dry lamination or heat lamination can be used.

  Although the thickness of the adhesion layers 14 and 23 is not specifically limited, It is preferable that they are 0.05 micrometer or more and 20 micrometers or less. Within this range, the adhesiveness of the adhesive layers 14 and 23 will be good.

(TEMPO oxidation of cellulose raw material)
70 g of softwood kraft pulp was suspended in 3500 g of distilled water, and a solution of 0.7 g of TEMPO and 7 g of sodium bromide dissolved in 350 g of distilled water was added and cooled to 20 ° C. 450 g of sodium hypochlorite aqueous solution having a concentration of 2 mol / L and a density of 1.15 g / mL was added dropwise thereto to initiate an oxidation reaction. The temperature in the system was always kept at 20 ° C., and the decrease in pH during the reaction was kept at pH 10 by adding a 0.5N aqueous sodium hydroxide solution. When sodium hydroxide reached 3.00 mmol / g based on the mass of cellulose, an excessive amount of ethanol was added to stop the reaction. Thereafter, filtration and washing with distilled water were repeated using a glass filter to obtain oxidized pulp.
(Measurement of carboxy group content of oxidized cellulose)
Oxidized pulp obtained by the above TEMPO oxidation was weighed by 0.1 g in terms of solid content, dispersed in water at a concentration of 1%, and hydrochloric acid was added to adjust the pH to 2.5. Thereafter, the amount of carboxy groups (mmol / g) was determined by conductivity titration using a 0.5 M aqueous sodium hydroxide solution. The result was 1.6 mmol / g.
(Defibration treatment of oxidized cellulose)
1 g of oxidized pulp obtained by TEMPO oxidation was dispersed in 99 g of distilled water and refined with a juicer mixer for 30 minutes to obtain a CSNF aqueous dispersion having a CSNF concentration of 1%. The number average minor axis diameter of CSNF contained in the CSNF aqueous dispersion was 4 nm, and the number average major axis diameter was 1110 nm. Further, when steady viscoelasticity measurement was performed using a rheometer, the CSNF dispersion showed thixotropic properties.
(Preparation of silver nitrate aqueous solution)
Silver nitrate was dissolved in 50 mL of distilled water to prepare an aqueous silver nitrate solution.
(Preparation of aqueous sodium borohydride solution)
Sodium borohydride was dissolved in 50 mL of distilled water to prepare a sodium borohydride aqueous solution.
(Production of infrared shielding material)
To 50 g of 1% CSNF aqueous dispersion, 0.5 g of an aqueous silver nitrate solution was added with stirring at room temperature (25 ° C.). After stirring for 30 minutes, an aqueous sodium borohydride solution was added to produce an infrared shielding material.
<Example 1>
A CSNF aqueous dispersion was prepared by the above-described method, an aqueous silver nitrate solution was added to the CSNF aqueous dispersion, and sodium borohydride as a reducing agent was added after a while to obtain a silver / CSNF composite. The infrared shielding material was fractionated by centrifugation and dispersed in an aqueous solution of polyvinyl alcohol PVA124 (manufactured by Kuraray Co., Ltd.) to prepare a coating composition. A 50 μm PET film was subjected to corona treatment, and the coating composition was applied using a bar coater to a dry film thickness of 200 nm, and dried at 120 ° C.
<Example 2>
A CSNF aqueous dispersion was prepared in the same manner as in Example 1, an aqueous silver nitrate solution was added to the CSNF aqueous dispersion, and sodium borohydride as a reducing agent was added after a while to obtain an infrared shielding material. The silver / CSNF complex was fractionated by centrifugation, and dispersed in an aqueous solution of Arrowbase (registered trademark) SD-1200 (manufactured by Unitika Ltd.) to prepare a coating composition. A 50 μm PET film was subjected to corona treatment, and the coating composition was applied with a bar coater so that the dry film thickness was 200 nm, and dried at 120 ° C.
<Example 3>
A CSNF aqueous dispersion was prepared in the same manner as in Example 1, an aqueous silver nitrate solution was added to the CSNF aqueous dispersion, and sodium borohydride as a reducing agent was added after a while to obtain an infrared shielding material. The silver / CSNF complex was fractionated by centrifugation and dispersed in an aqueous solution of Arrowbase SD-1200 (manufactured by Unitika Ltd.) to prepare a coating composition. A 100 μm PET film was subjected to corona treatment, and the coating composition was applied with a bar coater so that the dry film thickness was 400 nm, and dried at 120 ° C.
<Example 4>
A CSNF aqueous dispersion was prepared in the same manner as in Example 1, an aqueous silver nitrate solution was added to the CSNF aqueous dispersion, and sodium borohydride as a reducing agent was added after a while to obtain a dispersion of an infrared shielding material. It was. The infrared shielding material was fractionated by centrifugation and dispersed in an aqueous solution of Arrow Base SD-1200 (manufactured by Unitika Ltd.) to prepare a coating composition. A 50 μm PET film was subjected to corona treatment, and the coating composition was applied using a bar coater so that the dry film thickness was 400 nm, and dried at 120 ° C.
<Example 5>
A CSNF aqueous dispersion was prepared in the same manner as in Example 1, an aqueous silver nitrate solution was added to the CSNF aqueous dispersion, and sodium borohydride as a reducing agent was added after a while to obtain a dispersion of an infrared shielding material. It was. The silver / CSNF composite was fractionated by centrifugation and kneaded into a resin GS Pla (registered trademark) FZ91P (manufactured by Mitsubishi Chemical Corporation) to form a film having a thickness of 20 μm.
<Comparative Example 1>
A silver nitrate aqueous solution was added to water, and sodium borohydride as a reducing agent was added after a while.
<Comparative Example 2>
Silver nitrate was added to polyvinyl alcohol PVA124 (manufactured by Kuraray Co., Ltd.), and sodium borohydride as a reducing agent was added after a while.
<Comparative Example 3>
Sodium borohydride as a reducing agent was added to the CSNF aqueous dispersion.
<Comparative example 4>
Silver nitrate was added to the CSNF aqueous dispersion.
<Comparative Example 5>
Corona treatment was applied to a 50 μm PET film.
<Comparative Example 6>
A coating composition containing only an aqueous solution of polyvinyl alcohol PVA124 (manufactured by Kuraray Co., Ltd.) was prepared. A 50 μm PET film was subjected to corona treatment, and the coating composition was applied using a bar coater so that the dry film thickness was 200 nm, and dried at 120 ° C.
<Comparative Example 7>
A coating composition containing only an aqueous solution of Arrowbase SD-1200 (manufactured by Unitika Ltd.) was prepared. A 50 μm PET film was subjected to corona treatment, and the coating composition was applied using a bar coater so that the dry film thickness was 200 nm, and dried at 120 ° C.
<Comparative Example 8>
It was kneaded into a molding material GSPla FZ91P (manufactured by Mitsubishi Chemical Corporation) and molded into a film shape so as to have a film thickness of 20 μm.

In Examples 1 to 4 and Comparative Examples 6 to 7, a hard coat layer was provided on the opposite side of the coating layer from the substrate, and an adhesive layer was provided on the opposite side of the substrate from the coating. In Example 5 and Comparative Example 8, a hard coat layer was provided on one side of the film-like composite composition or molding material, and an adhesive layer was provided on the other side. In Comparative Examples 1 to 4, an infrared shielding material could not be obtained.
(Formation of hard coat layer)
The hard coat layer was diluted with pentaerythritol acrylate (PETA) having a solid content of 100% by mass using isopropyl alcohol (IPA) so that the solid content concentration of PETA was 50%. To this diluted solution, 5 parts by mass of Irgacure (registered trademark) 184 (manufactured by BASF Japan Ltd.) is added to 100 parts by mass of PETA to prepare a paint for forming a hard coat layer. Worked.
(Formation of adhesive layer)
An adhesive layer was formed by coating olivine (registered trademark) BPS5296 (manufactured by Toyochem Co., Ltd.) on a polyester film so as to have a thickness of 10 μm, and was bonded to the opposite surface of the hard coat layer of the base material or infrared shielding composite composition .
(Evaluation method of complex formation)
The formation of the complex is observed using a scanning transmission electron microscope, a scanning electron microscope, and a transmission electron microscope. When the metal and fine cellulose form a complex, “○” is formed. If not, “×” was assigned.
(Infrared shielding evaluation method)
The infrared shielding property of the infrared shielding film was measured from 220 nm to 2500 nm using a spectrophotometer UV-3600 (Shimadzu Corporation) with the empty state as a reference. The infrared shielding performance was “◯” when the transmittance of light having a wavelength of 900 nm was 70% or less, and “X” when the transmittance was 70% or more. The shielding coefficient was determined according to JIS A5759.

  As shown in Table 1, in Examples 1 to 5, an infrared shielding film having a low shielding coefficient was obtained with an infrared shielding material having a transmittance at 900 nm of 60% or less. In Comparative Examples 1 to 4, no complex of metal and refined cellulose was observed. In Comparative Examples 5 to 8, the transmittance at 900 nm was not less than 70% and the shielding coefficient was close to 1.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the infrared shielding composition and infrared shielding film containing the infrared shielding material obtained by the low environmental load and simple process using biomass material.

DESCRIPTION OF SYMBOLS 1, 2 Infrared shielding film 11 Base material 12 Coating layer containing infrared shielding material 13 Hard coat layer 14 Adhesive layer 21 Composite layer of infrared shielding material and resin 22 Hard coat layer 23 Adhesive layer 3 Infrared shielding material 31 Metal fine particles (silver) Fine particles)
31a Primary particles of fine metal particles 32 Refined cellulose (CSNF)
32a Part taken into metal fine particle 32b Part exposed on metal fine particle surface 33 Front surface 34 Back surface 35 Side surface 36 PET layer 37 Embedded resin layer d Particle diameter h Thickness

Claims (14)

Comprising a composite of flat metal fine particles and at least one or more refined cellulose;
The flat metal fine particles are at least one kind of metal or a compound thereof,
The micronized cellulose has a minor axis number average axis diameter of 1 nm to 200 nm, a major axis number average axis diameter of 0.05 μm to 50 μm, and all are taken into the flat metal fine particles. Alternatively, a part is taken into the flat metal fine particles, and the rest is exposed on the surface of the flat metal fine particles,
An infrared shielding material having an absorption maximum in a wavelength region of 700 nm to 2500 nm.   The infrared shielding material according to claim 1, wherein the flat metal fine particles and the fine cellulose are inseparable.   The infrared shielding material according to claim 1, wherein the flat metal fine particles are silver. The infrared shielding material according to any one of claims 1 to 3 , wherein the amount of carboxy groups in the micronized cellulose is 0.1 mmol / g or more and 3.0 mmol / g or less. The infrared shielding material according to any one of claims 1 to 4 , wherein a thickness of the tabular metallic silver fine particles is 1 nm or more and 100 nm or less. Claims 1 comprises an infrared shielding material according to any one of 5, the coating composition. Further comprising at least one or more water-soluble polymers,
The water-soluble polymer is 1 part by mass or more at 85 ° C. with respect to 100 parts by mass of an alcohol aqueous solution containing 50% by mass of methanol, ethanol, propanol or isopropyl alcohol and at least one of water. The coating composition according to claim 6 , which is a compound having a molecular weight of 1000 or more that dissolves. The infrared shielding film which has a base material and the coating layer formed with the coating composition of Claim 6 or 7 on the at least one surface of the said base material. Comprising at least one or more of the molding material, and an infrared shielding material according to any one of claims 1 to 5, the infrared shielding film. The infrared shielding film according to claim 8 , wherein the base material includes any of polyolefin, polyester, polyamide, polystyrene, ethylene vinyl alcohol, polyvinyl chloride, polyimide, polyvinyl alcohol, polycarbonate, polyethersulfone, and acrylic cellulose. The molding material is polystyrene, ABS resin (A; acrylonitrile, B; butadiene, S; styrene), AS resin, polyethylene, EVA resin, polypropylene, methacrylic resin, cellulose acetate, polycarbonate, polyamide, polyacetal, polysulfone, polyethylene terephthalate, The infrared shielding film according to claim 9 , comprising any one of polybutylene terephthalate and vinyl chloride resin. The infrared shielding film according to any one of claims 8 to 11 , wherein the transmittance of light in a wavelength region of 900 nm or more and 1000 nm or less is 70% or less. The hard coat layer laminated | stacked on the said coating layer, The adhesive layer formed in the surface on the opposite side to the surface in which the said coating layer is formed of the said base material is further included of Claim 8 or 10 . Infrared shielding film. The molding material and the infrared shielding material form a composite layer,
A hard coat layer laminated on one side of the composite layer;
The infrared shielding film according to claim 9 or 11 , further comprising an adhesive layer formed on the other surface of the composite layer.