JP7353972B2 - Near-infrared absorbing fiber, its manufacturing method, and textile products using the same - Google Patents

Description

The present invention relates to a near-infrared absorbing fiber containing a material that absorbs infrared rays from sunlight and the like, a method for producing the same, and a textile product with high heat retention obtained by processing the fiber.

A variety of cold-weather clothing, interior goods, and leisure goods with enhanced heat retention effects have been devised and put into practical use. There are roughly two methods for increasing the heat retention effect. The first method is to physically increase the air layer in the winter clothing by, for example, controlling the weaving and knitting structure in the winter clothing or making the fibers used hollow or porous. This method maintains heat retention by reducing heat dissipation. The second method is, for example, in the cold-weather clothing, by chemically or physically processing the entire clothing or the fibers constituting the cold-weather clothing to radiate the heat generated from the human body back to the human body. This is a method of actively storing heat and improving heat retention by converting some of the sunlight that winter clothing receives into heat.

As the first method mentioned above, methods have been adopted such as increasing the air space in clothing, making the fabric thicker, making the mesh finer, or making the clothing darker. For example, clothing used in winter, such as sweaters. Furthermore, for example, clothing that has been commonly used for winter sports has a batting between the outer fabric and the lining, and the thickness of the air layer in the batting maintains heat retention. However, when padding is added, the clothing becomes heavy and bulky, which causes problems for sports applications that require ease of movement. In order to solve these problems, in recent years, the second method mentioned above, which actively utilizes internally generated heat or heat from the outside, has begun to be adopted.

One way to implement the second method is to deposit metals such as aluminum or titanium on the lining of clothing, and reflect the radiant heat emitted from the body on the metal-deposited surface, thereby actively reducing heat. There are known methods to prevent the spread. However, with these methods, not only does it cost a lot to vapor-deposit metal onto clothing, but also the yield is poor due to uneven vapor deposition, which results in an increase in the price of the product itself.

In addition, as another method for carrying out the second method, ceramic particles such as alumina, zirconia, and magnesia are kneaded into the fiber itself, and the far-infrared radiation effect of these inorganic particles and light are converted into heat. A method has been proposed that utilizes the changing effect, that is, a method that actively incorporates external energy.

For example, Patent Document 1 describes inorganic fine particles such as silica or barium sulfate that have near-infrared radiation characteristics and contain at least one kind of metal or metal ion with a thermal conductivity of 0.3 kcal/ ^m2 ·sec·°C or higher. A technique is described in which near-infrared emissive fibers containing one or more of the inorganic fine particles are prepared, and the fibers are used to improve heat retention.

Patent Document 2 discloses that ceramic fine particles having a light absorption heat conversion ability and far infrared radiation ability and aluminum oxide fine particles are contained in the fiber in an amount of 0.1 to 20% by weight based on the weight of the fiber. It is described that the fiber exhibits excellent heat retention properties.

Patent Document 3 proposes an infrared absorbing processed fiber product in which a binder resin containing an infrared absorber made of an amino compound, an ultraviolet absorber used as necessary, and various stabilizers is dispersed and fixed.

Patent Document 4 discloses that dyeing is performed by combining a dye selected from direct dyes, reactive dyes, naphthol dyes, and vat dyes that has a property of absorbing more in the near-infrared region than black dye, and other dyes. A near-infrared absorption processing method has been proposed to obtain a cellulose-based fiber structure that absorbs near-infrared rays (within the near-infrared wavelength range of 750 to 1,500 nm, the spectral reflectance of the fabric is 65% or less). There is.

In Patent Document 5 and Patent Document 6, the present inventors proposed a material that has high transmittance and low reflectance for visible light, but low transmittance and high reflectance for light in the near-infrared region. We select hexaboride, tungsten oxide fine particles, and composite tungsten oxide fine particles, and propose fibers containing these fine particles as near-infrared absorbing components, and textile products obtained by processing the fibers.

Japanese Patent Application Publication No. 11-279830 Japanese Patent Application Publication No. 5-239716 Japanese Patent Application Publication No. 8-3870 Japanese Patent Application Publication No. 9-291463 Japanese Patent Application Publication No. 2005-9024 Japanese Patent Application Publication No. 2006-132042

When inorganic fine particles such as silica containing metal etc. that have near-infrared emitting properties are prepared and near-infrared emissive fibers containing the inorganic fine particles are manufactured, since the amount of the inorganic fine particles added to the fiber is large, the fiber There have been problems such as the increased specific gravity of the fibers, which makes clothes heavier and the difficulty of uniformly dispersing them during melt-spinning. Furthermore, a technique is also known in which metal powder such as aluminum or titanium is attached to fibers by adhesion or vapor deposition to provide a radiation reflecting effect and improve heat retention. However, the color of the fibers changes significantly due to fixation and vapor deposition, which limits its uses, increases the cost associated with vapor deposition, and causes vapor deposition spots due to delicate handling of the fabric during the preparation process before vapor deposition, and when washing or wearing the fabric. There have been various problems such as a drop in heat retention performance due to the vapor-deposited metal falling off due to friction.

In the method of incorporating ceramic fine particles and aluminum oxide fine particles into the fiber, since the infrared absorbing agent used is an organic material or black dye, there are problems in that it deteriorates significantly due to heat and humidity and has poor weather resistance. are doing. Furthermore, since the material is colored darkly by applying the material, it cannot be used for light-colored products, and there is a drawback that the fields in which it can be used are limited.

In the case of fibers containing hexaboride fine particles, higher near-infrared absorption properties are required in order to make practical textile products with heat retention properties, and there is still room for improvement in near-infrared absorption properties in such fibers as well. It had
According to the applicant's study, tungsten oxide fine particles or composite tungsten oxide fine particles produced by the method disclosed in Patent Document 6, for example, have low crystallinity. The near-infrared absorption properties of the material were not sufficient.

The present invention was made to solve these problems, and provides a near-infrared absorbing fiber that efficiently absorbs near-infrared rays from sunlight and has excellent heat retention, a method for producing the same, and the fiber. The purpose is to provide textile products using.

The present inventors conducted extensive research to achieve the above object. Then, in the X-ray diffraction (sometimes referred to as "XRD" in the present invention) pattern of the composite tungsten oxide ultrafine particles, the composite tungsten oxide ultrafine particles have a peak top intensity ratio value of a predetermined value. I found out. Specifically, when the value of the XRD peak intensity related to the (220) plane of a silicon powder standard sample (manufactured by NIST, 640c) is set to 1, the value of the ratio of the XRD peak top intensity of the composite tungsten oxide ultrafine particles These are composite tungsten oxide ultrafine particles in which the tungsten oxide is 0.13 or more.
The composite tungsten oxide ultrafine particles were transparent in the visible light region and had excellent near-infrared absorption characteristics due to their high crystallinity. Moreover, the composite tungsten oxide ultrafine particles were versatile and capable of producing a dispersion containing the composite tungsten oxide ultrafine particles with high productivity.

Fibers in which the composite tungsten oxide ultrafine particles are dispersed in an appropriate medium and the dispersion is contained on the surface and/or inside the fibers have a higher light absorption ability than near-infrared absorbing fibers according to conventional technology. The present inventors have discovered that sunlight, especially light in the near-infrared region, can be absorbed more efficiently without using the interference effect, and at the same time, light in the visible region can be transmitted, and the present invention has been completed.

That is, the first invention for solving the above problems is as follows:
A near-infrared absorbing fiber containing ultrafine particles having near-infrared absorbing properties inside the fiber,
The ultrafine particles having near-infrared absorption characteristics are composite tungsten oxide ultrafine particles,
The composite tungsten oxide ultrafine particles have a ratio of XRD peak top intensity of 0.13 or more when the XRD peak intensity value of the (220) plane of a silicon powder standard sample (manufactured by NIST, 640c) is set to 1. This is a near-infrared absorbing fiber characterized by being made of ultrafine composite tungsten oxide particles.
The second invention is
The composite tungsten oxide ultrafine particles have a general formula MxWyOz (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, One or more elements selected from Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, Yb, W is tungsten, O is oxygen, 0.001≦x/y≦1 , 2.0<z/y≦3.0) The near-infrared absorbing fiber according to the first aspect of the invention is characterized in that it is a composite tungsten oxide ultrafine particle expressed as: , 2.0<z/y≦3.0).
The third invention is
The near-infrared absorbing fiber according to the first or second invention, wherein the composite tungsten oxide ultrafine particles have a crystallite diameter of 1 nm or more and 200 nm or less.
The fourth invention is
The near-infrared absorbing fiber according to any one of the first to third inventions, wherein the composite tungsten oxide ultrafine particles include a hexagonal crystal structure.
The fifth invention is
The near-infrared absorbing fiber according to any one of the first to fourth aspects of the invention, wherein the volatile component content of the composite tungsten oxide ultrafine particles is 2.5% by mass or less.
The sixth invention is
According to any one of the first to fifth inventions, wherein the content of the composite tungsten oxide ultrafine particles is 0.001% by mass or more and 80% by mass or less based on the solid content of the fiber. is a near-infrared absorbing fiber.
The seventh invention is
A fiber further containing fine particles of a far-infrared emitting substance on the surface and/or inside of the near-infrared absorbing fiber according to any one of the first to sixth inventions,
The near-infrared absorbing fiber is characterized in that the content of the fine particles of the far-infrared emitting substance is 0.001% by mass or more and 80% by mass or less based on the solid content of the fiber.
The eighth invention is
The fibers are selected from one or more of synthetic fibers, semi-synthetic fibers, natural fibers, regenerated fibers, inorganic fibers, or mixed yarns formed by blending, doubling, or blending these fibers. The near-infrared absorbing fiber according to any one of the first to seventh aspects of the invention.
The ninth invention is
The synthetic fibers are selected from polyurethane fibers, polyamide fibers, acrylic fibers, polyester fibers, polyolefin fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, and polyether ester fibers. The near-infrared absorbing fiber according to the eighth invention is characterized in that it is one or more kinds of synthetic fibers.
The tenth invention is
The method according to the eighth or ninth invention, wherein the semi-synthetic fiber is one or more semi-synthetic fibers selected from cellulose fibers, protein fibers, chlorinated rubber, and hydrochloric acid rubber. It is an infrared absorbing fiber.
The eleventh invention is
The near-infrared absorbing fiber according to any one of the eighth to tenth inventions, characterized in that the natural fiber is any one or more natural fibers selected from vegetable fibers, animal fibers, and mineral fibers. be.
The twelfth invention is
Items 8 to 11, characterized in that the regenerated fiber is any one or more regenerated fibers selected from cellulose fibers, protein fibers, algin fibers, rubber fibers, chitin fibers, and mannan fibers. The near-infrared absorbing fiber according to any one of the inventions.
The thirteenth invention is
The near-infrared absorbing device according to any one of the eighth to twelfth inventions, wherein the inorganic fiber is any one or more inorganic fibers selected from metal fibers, carbon fibers, and silicate fibers. It is a fiber.
The fourteenth invention is
The first to thirteenth inventions are characterized in that the surface of the composite tungsten oxide ultrafine particles is coated with a compound containing any one or more elements selected from silicon, zirconium, titanium, and aluminum. The near-infrared absorbing fiber according to any one of the above.
The fifteenth invention is
The near-infrared absorbing fiber according to the fourteenth invention, wherein the compound is an oxide.
The 16th invention is
A textile product characterized in that the near-infrared absorbing fiber according to any one of the first to fifteenth inventions is processed.
The seventeenth invention is
A method for producing a near-infrared absorbing fiber containing ultrafine particles having near-infrared absorbing properties, the method comprising:
The ultrafine particles having near-infrared absorption characteristics are composite tungsten oxide ultrafine particles,
The composite tungsten oxide particles have an XRD peak top intensity ratio value of 0.13 or more, where the value of the XRD peak intensity of the (220) plane of a silicon powder standard sample (manufactured by NIST, 640c) is set to 1. It is obtained by firing it so that
The method for producing a near-infrared absorbing fiber is characterized in that the obtained composite tungsten oxide particles are incorporated into the fiber while maintaining the ratio of the XRD peak top intensities to 0.13 or more.

The near-infrared absorbing fiber according to the present invention is a fiber containing composite tungsten oxide ultrafine particles as a near-infrared absorbing component, which absorbs sunlight, particularly light in the near-infrared region, more efficiently, and at the same time absorbs sunlight in the visible light region. It is a fiber that exhibits excellent heat retention by allowing light to pass through. Due to its excellent near-infrared absorption properties, textile products using the fibers of the present invention can be used for textile products such as cold-weather clothing, sports clothing, stockings, curtains, etc. that require heat retention, and other industrial textiles. It can be used for various purposes such as materials.

1 is a conceptual diagram of a high frequency plasma reaction device used in the present invention. 1 is an X-ray diffraction pattern of fine particles before pulverization according to Example 1.

Embodiments for carrying out the near-infrared absorbing fiber according to the present invention will be described in the order of [1] composite tungsten oxide ultrafine particles and [2] near-infrared absorbing fiber.

[1] Composite tungsten oxide ultrafine particles Regarding the composite tungsten oxide ultrafine particles according to the present invention, [a] Characteristics of the composite tungsten oxide ultrafine particles, [b] Synthesis method of composite tungsten oxide ultrafine particles, [c] Composite The volatile components of ultrafine tungsten oxide particles, the drying method thereof, and [d] the composite ultrafine tungsten oxide particle dispersion will be explained in this order.

[a] Characteristics of composite tungsten oxide ultrafine particles The composite tungsten oxide ultrafine particles according to the present invention have near-infrared absorption characteristics, and the XRD peak intensity related to the (220) plane of a silicon powder standard sample (manufactured by NIST, 640c) The value of the ratio of the XRD peak top intensity of the composite tungsten oxide ultrafine particles when the value of is 1 is 0.13 or more.
The following describes the characteristics of the composite tungsten oxide ultrafine particles according to the present invention: (1) XRD peak top intensity ratio, (2) composition, (3) crystal structure, (4) BET specific surface area, (5) dispersed particle diameter. , (6) volatile components, (7) surface coating, and (8) summary.

(1) Ratio of XRD peak top intensities A powder X-ray diffraction method is used to measure the XRD peak top intensities of the above-mentioned composite tungsten oxide ultrafine particles. At this time, in order to give objective quantitative properties to the measurement results among the samples of composite tungsten oxide ultrafine particles, a standard sample is determined, the peak intensity of the standard sample is measured, and the peak intensity of the standard sample is compared with the peak intensity of the standard sample. The XRD peak top intensity of each ultrafine particle sample was measured using the value of the ratio of the XRD peak top intensities of the ultrafine particle sample.

Here, the standard sample used is a silicon powder standard sample (manufactured by NIST, 640c), which is universal in the industry. The (220) plane was used as a reference.

Furthermore, in order to ensure objective quantification, other measurement conditions were also kept constant.
Specifically, an ultrafine particle sample is filled into a sample holder with a depth of 1.0 mm by a known operation for X-ray diffraction measurement. Specifically, in order to avoid preferential orientation (crystal orientation) in the ultrafine particle sample, it is preferable to fill the sample randomly and gradually, and to fill it as evenly and as densely as possible.

As an X-ray source, an X-ray tube with an anode target material of Cu was used with an output setting of 45 kV/40 mA, and a step scan mode (step size: 0.0165° (2θ) and counting time: 0.022 msec) was used. /step) was decided to be measured by θ-2θ powder X-ray diffraction method.
At this time, since the XRD peak intensity changes depending on the usage time of the X-ray tube, it is desirable that the usage time of the X-ray tube is almost the same between samples. In order to ensure objective quantification, it is necessary that the difference in X-ray tube use time between samples be kept to at most one-twentieth or less of the expected lifespan of the X-ray tube. A more desirable measurement method is a method in which a silicon powder standard sample is measured every time the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles is measured, and the ratio of the XRD peak top intensities is calculated. This measurement method was used in the present invention. The expected lifespan of the X-ray tube of commercially available X-ray equipment is more than several thousand hours, and the measurement time per sample is often less than a few hours. Therefore, by implementing the preferred measurement method described above, The influence of the tube usage time on the XRD peak top intensity ratio can be made negligibly small.
Further, in order to keep the temperature of the X-ray tube constant, it is desirable to keep the temperature of the cooling water for the X-ray tube constant.

Note that the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles is an X-ray diffraction pattern of a large number of composite tungsten oxide ultrafine particles constituting the composite tungsten oxide powder sample. It is also an X-ray diffraction pattern of composite tungsten oxide ultrafine particles after they have been crushed, pulverized, or dispersed to obtain a composite tungsten oxide ultrafine particle dispersion, which will be described later. The X-ray diffraction pattern of the composite tungsten oxide ultrafine particles according to the present invention or the composite tungsten oxide ultrafine particles contained in the dispersion thereof is the same as the X-ray diffraction pattern of the composite tungsten oxide ultrafine particle dispersion according to the present invention. is also maintained.

The XRD peak top intensity is the peak intensity at 2θ with the highest peak count in the X-ray diffraction pattern. In hexagonal Cs composite tungsten oxide and Rb composite tungsten oxide, the peak count 2θ in the X-ray diffraction pattern appears in the range of 25° to 31°.

The XRD peak top intensity of the above-mentioned composite tungsten oxide ultrafine particles has a close relationship with the crystallinity of the ultrafine particles, and further has a close relationship with the free electron density in the ultrafine particles. The present inventors have discovered that the XRD peak top intensity greatly affects the near-infrared absorption characteristics of the composite tungsten oxide ultrafine particles. Specifically, it has been found that when the value of the XRD peak top intensity ratio is 0.13 or more, the free electron density in the ultrafine particles is ensured and desired near-infrared absorption characteristics can be obtained. . Note that the value of the XRD peak top intensity ratio may be 0.13 or more, and preferably 0.7 or less.

The XRD peak top intensity of the composite tungsten oxide ultrafine particles will be explained from a different perspective.
The value of the XRD peak top ratio of the composite tungsten oxide ultrafine particles of 0.13 or more indicates that composite tungsten oxide ultrafine particles with good crystallinity and containing almost no foreign phase are obtained. That is, it is considered that the obtained composite tungsten oxide ultrafine particles are not amorphous (non-crystalline). As a result, by dispersing ultrafine composite tungsten oxide particles that contain almost no foreign phase into a liquid medium such as an organic solvent that transmits visible light, or a solid medium such as resin that transmits visible light, near-infrared It is considered that sufficient absorption characteristics can be obtained.
In the present invention, the term "different phase" refers to a phase of a compound other than the composite tungsten oxide. Further, by analyzing the X-ray diffraction pattern obtained when measuring the XRD peak top intensity, the crystal structure and crystallite diameter of the composite tungsten oxide ultrafine particles can be determined.

(2) Composition The composite tungsten oxide ultrafine particles according to the present invention have the general formula MxWyOz (where M is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, One or more elements selected from Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, Yb, W is tungsten, O is oxygen, 0 It is preferable that the composite tungsten oxide ultrafine particles be expressed as: .001≦x/y≦1, 2.0<z/y≦3.0).

The composite tungsten oxide ultrafine particles represented by the general formula MxWyOz will be explained.
The M elements, x, y, and z in the general formula MxWyOz and their crystal structure have a close relationship with the free electron density of the composite tungsten oxide ultrafine particles, and have a large influence on the near-infrared absorption characteristics.

Generally, tungsten trioxide (WO ₃ ) has low near-infrared absorption characteristics because there are no effective free electrons.
Here, the present inventors added M element (however, M element is H, He, alkali metal, alkaline earth metal, rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, One or more elements selected from among Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, I, and Yb) to form a composite tungsten oxide. Then, free electrons are generated in the composite tungsten oxide, and absorption characteristics derived from free electrons are expressed in the near-infrared region, making the composite tungsten oxide effective as a near-infrared absorbing material with a wavelength of around 1000 nm. It was discovered that this material remains chemically stable and is effective as a near-infrared absorbing material with excellent weather resistance. Furthermore, it is preferable that the M element is Cs, Rb, K, Tl, Ba, Cu, Al, Mn, or In. Among them, when the M element is Cs or Rb, the composite tungsten oxide has a hexagonal structure. It becomes easier to take. As a result, it has been found that it transmits visible light and absorbs near-infrared rays, which is particularly preferable for reasons described later.

Here, the findings of the present inventors regarding the value of x indicating the amount of addition of the M element will be explained.
If the value of x/y is 0.001 or more, a sufficient amount of free electrons will be generated and the desired near-infrared absorption characteristics can be obtained. As the amount of M element added increases, the amount of free electrons supplied increases and the near-infrared absorption characteristics also improve, but this effect is saturated when the value of x/y is about 1. Further, it is preferable that the value of x/y is 1 or less, since it is possible to avoid the formation of impurity phases in the composite ultrafine tungsten particles.

Next, the findings of the present inventors regarding the value of z, which indicates the control of the amount of oxygen, will be explained.
In the composite tungsten oxide ultrafine particles represented by the general formula MxWyOz, the value of z/y is preferably 2.0<z/y≦3.0, more preferably 2.2≦z/y≦3. .0, more preferably 2.6≦z/y≦3.0, most preferably 2.7≦z/y≦3.0. If the value of z/y is 2.0 or more, it is possible to avoid the appearance of a crystal phase of WO ₂ which is not the intended purpose in the composite tungsten oxide, and it is also chemically stable as a material. This is because it can be used as an effective infrared absorbing material. On the other hand, if the value of z/y is 3.0 or less, the required amount of free electrons will be generated in the tungsten oxide, making it an efficient infrared absorbing material.

(3) Crystal structure The composite tungsten oxide ultrafine particles according to the present invention have a tetragonal or cubic tungsten bronze structure in addition to a hexagonal structure, but they are effective as a near-infrared absorbing material in any of the structures. be. However, the absorption position in the near-infrared region tends to change depending on the crystal structure of the composite tungsten oxide ultrafine particles. That is, the absorption position in the near-infrared region tends to shift toward longer wavelengths in tetragonal crystals than in cubic crystals, and further toward longer wavelengths in hexagonal crystals than in tetragonal crystals. Further, along with the variation of the absorption position, the hexagonal crystal has the least absorption in the visible light region, followed by the tetragonal crystal, and the cubic crystal has the highest absorption among these.
From the above knowledge, it is most preferable to use hexagonal tungsten bronze for applications that transmit more light in the visible light region and absorb more light in the near-infrared region. When the composite tungsten oxide ultrafine particles have a hexagonal crystal structure, the fine particles have improved transmission in the visible light region and improved absorption in the near-infrared region.

That is, in the composite tungsten oxide, if the value of the XRD peak top intensity ratio satisfies the above-mentioned predetermined value and it is a hexagonal tungsten bronze, excellent optical properties will be exhibited. In addition, when the composite tungsten oxide ultrafine particles have an orthorhombic crystal structure or a monoclinic crystal structure similar to WO _2.72 called Magnelli phase, they may not absorb infrared rays. It is excellent and may be effective as a near-external radiation absorbing material.

From the above findings, when the composite tungsten oxide ultrafine particles having a hexagonal crystal structure have a uniform crystal structure, the amount of the added M element should be 0.2 or more and 0.5 or less in terms of x/y. Preferably, 0.29≦x/y≦0.39 is more preferable. Theoretically, it is considered that when z/y=3, the value of x/y is 0.33, so that the added M element is arranged in all the hexagonal voids. Typical examples include Cs _0.33 WO ₃ , Cs _0.03 Rb _0.30 WO ₃ , Rb _0.33 WO ₃ , K _0.33 WO ₃ , Ba _0.33 WO ₃ and the like. .

Further, the composite tungsten oxide ultrafine particles according to the present invention are preferably single crystals in which the volume ratio of the amorphous phase is 50% or less.
When the composite tungsten oxide ultrafine particles are single crystals with an amorphous phase volume ratio of 50% or less, the crystallite diameter can be reduced to 200 nm or less while maintaining the XRD peak top intensity. By setting the crystallite size of the composite tungsten oxide ultrafine particles to 200 nm or less, the dispersed particle size can be set to 1 nm or more and 200 nm or less, more preferably 10 nm or more and 200 nm or less.
That is, if the ultrafine composite tungsten particles are single crystals with an amorphous phase volume ratio of 50% or less, the ultrafine composite tungsten particles will have an XRD peak top intensity ratio of 0.13 or more, and have sufficient near-infrared absorption characteristics. It is preferable that it is expressed in
On the other hand, from the viewpoint of near-infrared absorption characteristics, the crystallite diameter of the composite tungsten oxide ultrafine particles is preferably 10 nm or more. Further, it is more preferable that the crystallite diameter of the composite tungsten oxide ultrafine particles is 200 nm or less and 10 nm or more. This is because when the crystallite diameter is in the range of 200 nm or less and 10 nm or more, the value of the XRD peak top intensity ratio exceeds 0.13, and even more excellent near-infrared absorption characteristics are exhibited.
Note that the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles in the composite tungsten oxide ultrafine particle dispersion after being crushed, pulverized, or dispersed, which will be described later, is based on the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles in the composite tungsten oxide ultrafine particle dispersion according to the present invention. The X-ray diffraction pattern of the composite tungsten oxide ultrafine particles obtained by removing the volatile components of the composite tungsten oxide ultrafine particles and the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles contained in the dispersion obtained from the dispersion liquid are also maintained. Ru.
As a result, the crystal state such as the XRD pattern, XRD peak top intensity, and crystallite diameter of the composite tungsten oxide ultrafine particles in the composite tungsten oxide ultrafine particle dispersion and the composite tungsten ultrafine particle dispersion obtained from the dispersion is The effects of the present invention are exhibited as long as the composite tungsten oxide ultrafine particles that can be used in the present invention are in a crystalline state.

In addition, the fact that the composite tungsten oxide ultrafine particles are single crystals is because in electron microscope images such as transmission electron microscopes, no crystal grain boundaries are observed inside each fine particle, and only uniform lattice stripes are observed. It can be confirmed. In addition, the fact that the volume ratio of the amorphous phase in the composite tungsten oxide ultrafine particles is 50% or less means that uniform lattice stripes are observed throughout the particles in transmission electron microscopy images, and most of the parts where the lattice stripes are unclear are This can be confirmed by not being observed. Since the amorphous phase often exists at the outer periphery of the particle, it is often possible to calculate the volume ratio of the amorphous phase by focusing on the outer periphery of the particle. For example, in a truly spherical composite tungsten oxide ultrafine particle, if an amorphous phase with unclear lattice fringes exists in a layer on the outer periphery of the particle, if the thickness is 10% or less of the particle diameter, the composite tungsten oxide The volume ratio of the amorphous phase in the ultrafine particles is 50% or less.
On the other hand, the composite tungsten oxide ultrafine particles are applied to a coating film constituting the composite tungsten oxide ultrafine particle dispersion, a film obtained by subjecting the coating film to a predetermined operation and curing the resin of the coating film (in the present invention, a "cured film" is used). ), if it is dispersed inside a resin, etc., the difference between the average particle diameter of the dispersed composite tungsten oxide ultrafine particles minus the crystallite diameter is 20% or less. For example, the composite tungsten oxide ultrafine particles can be said to be a single crystal with an amorphous phase volume ratio of 50% or less, and are substantially single crystal.
Here, the average particle diameter of the composite tungsten oxide ultrafine particles is determined by measuring the particle diameter of 100 composite tungsten oxide ultrafine particles using an image processing device from a transmission electron microscope image of the composite tungsten oxide ultrafine particle dispersion. , can be obtained by calculating the average value. and a step of synthesizing the composite tungsten oxide ultrafine particles such that the difference between the average particle diameter and the crystallite diameter of the composite tungsten oxide ultrafine particles dispersed in the composite tungsten oxide ultrafine particle dispersion is 20% or less, What is necessary is just to adjust a pulverization process and a dispersion process suitably according to manufacturing equipment.

(4) BET specific surface area The BET specific surface area of the above-mentioned composite tungsten oxide ultrafine particles is closely related to the particle size distribution of the ultrafine particles. This greatly affects productivity, the near-infrared absorption characteristics of the ultrafine particles themselves, and the light resistance that suppresses photocoloring.

The fact that the BET specific surface area of the ultrafine particles is small indicates that the crystallite diameter of the ultrafine particles is large. Therefore, if the BET specific surface area of the ultrafine particles is greater than or equal to a predetermined value, it is possible to produce a near-infrared absorbing dispersion that is transparent in the visible light region and can suppress the blue haze phenomenon described above. There is no need to pulverize the ultrafine particles to make them finer, and it is possible to improve the productivity of the near-infrared absorbing dispersion liquid.

On the other hand, the fact that the BET specific surface area of the ultrafine particles is less than a predetermined value, for example, 200 m ² /g or less, indicates that the BET particle size is 2 nm or more when the particle shape is assumed to be perfectly spherical. This means that there are almost no ultrafine particles with a crystallite diameter of less than 1 nm that do not contribute to near-infrared absorption characteristics. Therefore, when the BET specific surface area of the ultrafine particles is less than or equal to a predetermined value, the near-infrared absorption characteristics and light resistance of the ultrafine particles are ensured.

Of course, if the BET specific surface area of the ultrafine particles is 200 m ² /g or less and the above-mentioned XRD peak top intensity value is a predetermined value or more, the crystallite size of less than 1 nm, which does not contribute to near-infrared absorption characteristics, Since there are almost no ultrafine particles and there are ultrafine particles with good crystallinity, it is thought that the near-infrared absorption characteristics and light resistance of the ultrafine particles are ensured.

In the measurement of the BET specific surface area of the composite tungsten oxide ultrafine particles described above, nitrogen gas, argon gas, krypton gas, xenon gas, etc. are used as gases used for adsorption. However, when the measurement sample is a powder and has a specific surface area of 0.1 m ² /g or more, such as the composite tungsten oxide ultrafine particles according to the present invention, nitrogen gas, which is relatively easy to handle and low cost, is used. It is desirable to do so. The BET specific surface area of the composite tungsten oxide ultrafine particles is preferably 30.0 m ² /g or more and 120.0 m 2 /g or less, more preferably 30.0 ^{m 2 /} g or more and 90.0 m ² /g or less. , more preferably 35.0 m ² /g or more and 70.0 m ² /g or less. The BET specific surface area of the composite tungsten oxide ultrafine particles is desirably the above-mentioned value both before and after the pulverization and dispersion when obtaining the composite tungsten oxide ultrafine particle dispersion.

(5) Dispersed particle size The dispersed particle size of the composite tungsten oxide ultrafine particles is preferably 200 nm or less, more preferably 200 nm or less and 10 nm or more. The dispersed particle diameter of the composite tungsten oxide ultrafine particles is preferably 200 nm or less, and this also applies to the composite tungsten oxide ultrafine particles in the composite tungsten oxide ultrafine particle dispersion. If the dispersed particle size is 200 nm or less, spinnability such as clogging of the filter and yarn breakage can be avoided during the subsequent fiberizing process such as spinning and stretching. Furthermore, even if spinning can be carried out, problems such as yarn breakage may occur during the drawing process, and it may also become difficult to mix and disperse the particles uniformly in the spinning raw material. The diameter is preferably 200 nm or less.

On the other hand, when considering the dyeability and other design aspects of clothing and other textile materials containing composite tungsten oxide ultrafine particles, the ultrafine particles must efficiently absorb near-infrared rays while maintaining transparency. . The near-infrared absorbing component containing the composite tungsten oxide ultrafine particles according to the present invention largely absorbs light in the near-infrared region, particularly in the wavelength range of 900 to 2200 nm, so its transmitted color tone ranges from blue to green. There are many. Here, if the dispersed particle diameter of the ultrafine particles is smaller than 200 nm, coloring due to the composite tungsten oxide ultrafine particles becomes less likely to occur in textile materials such as clothing. Therefore, when avoiding coloring is important, the dispersed particle diameter of the composite tungsten oxide ultrafine particles is set to 150 nm or less, more preferably 100 nm or less. On the other hand, if the dispersed particle size is 1 nm or more, industrial production is easy.

(6) Volatile Component The above-described composite tungsten oxide ultrafine particles may contain a component that volatilizes upon heating (sometimes referred to as a "volatile component" in the present invention). The volatile components are components that are adsorbed by the composite tungsten oxide ultrafine particles when they are exposed to the storage atmosphere or the atmosphere, or during the synthesis process. Here, specific examples of the volatile component include water and a solvent for the dispersion liquid described later. It is an ingredient that

The volatile components and their content in composite tungsten oxide ultrafine particles are related to the amount of moisture adsorbed when the ultrafine particles are exposed to the atmosphere, etc., and the amount of solvent remaining in the drying process of the ultrafine particles. The volatile component and its content may greatly influence the dispersibility when the ultrafine particles are dispersed in a resin or the like.
For example, if the resin used in the near-infrared absorbing dispersion described below has poor compatibility with the volatile components adsorbed on the ultrafine particles, and the content of the volatile components in the ultrafine particles is high, This may cause haze (deterioration in transparency) of the produced near-infrared absorbing dispersion. In addition, when the produced near-infrared absorbing dispersion is placed outdoors for a long period of time and exposed to sunlight or wind and rain, the composite tungsten oxide ultrafine particles may be detached from the near-infrared absorbing dispersion, or the film may be damaged. Peeling may occur. That is, the deterioration in the compatibility between the ultrafine particles and the resin causes deterioration of the produced near-infrared absorbing dispersion. In other words, whether or not the composite tungsten oxide ultrafine particles containing a large amount of volatile components are well dispersed may depend on the compatibility with the dispersion medium used in the dispersion system. It means that. Therefore, if the volatile component content of the composite tungsten oxide ultrafine particles according to the present invention is a predetermined amount or less, wide versatility is exhibited.

According to the studies conducted by the present inventors, if the content of volatile components in composite tungsten oxide ultrafine particles is 2.5% by mass or less, the ultrafine particles will be effective against the dispersion medium used in most dispersion systems. It was discovered that the composite tungsten oxide ultrafine particles are dispersible and versatile.
On the other hand, it has also been found that there is no particular restriction on the lower limit of the content of the volatile components.
As a result, if ultrafine particles with a content of volatile components of 2.5% by mass or less are not excessively secondary agglomerated, a tumbler, Nauta mixer, Henschel mixer, super mixer, planetary mixer, etc. The ultrafine particles can be dispersed in resin, etc. using a method of uniformly mixing (including melt mixing) with a mixer, and a kneading machine such as a Banbury mixer, kneader, roll, single screw extruder, or twin screw extruder. .

The content of volatile components in the composite tungsten oxide ultrafine particles can be measured by thermal analysis. Specifically, the weight loss may be measured by holding the composite tungsten oxide ultrafine particle sample at a temperature lower than the temperature at which the composite tungsten oxide ultrafine particles thermally decompose and higher than the temperature at which the volatile components volatilize. . Moreover, when identifying volatile components, gas mass spectrometry may be used in combination.

(7) Surface coating In order to improve the weather resistance of the composite tungsten oxide ultrafine particles, the surface of the composite tungsten oxide ultrafine particles is coated with a compound containing one or more elements selected from silicon, zirconium, titanium, and aluminum. It is also preferable to do so. These compounds are basically transparent, and their addition does not reduce the visible light transmittance of the composite tungsten oxide ultrafine particles, so that the design of the fibers is not impaired. Moreover, it is preferable that these compounds are oxides. The oxides of these compounds have a high ability to emit far-infrared rays, and they have the ability to receive the energy absorbed by ultrafine composite tungsten oxide particles, which are near-infrared absorbing materials, and convert that energy into thermal energy at mid- and far-infrared wavelengths, and radiate it. have. Therefore, the oxides of these compounds are also effective in keeping the fibers warm.

(8) Summary The XRD peak top intensity value and BET specific surface area of the composite tungsten oxide ultrafine particles described in detail above can be controlled by predetermined manufacturing conditions. Specifically, the temperature at which the ultrafine particles are generated by a thermal plasma method or solid phase reaction method (calcination temperature), the generation time (calcination time), the generation atmosphere (calcination atmosphere), the form of the precursor raw material, It can be controlled by appropriately setting manufacturing conditions such as post-generation annealing treatment and doping with impurity elements. On the other hand, the content of volatile components in composite tungsten oxide ultrafine particles depends on appropriate manufacturing conditions such as the storage method and storage atmosphere of the ultrafine particles, the temperature when drying the ultrafine particle dispersion, drying time, and drying method. Can be controlled by settings. The content of volatile components in the composite tungsten oxide ultrafine particles does not depend on the crystal structure of the composite tungsten oxide ultrafine particles or the synthesis method such as the thermal plasma method or solid phase reaction described below.

[b] Method for synthesizing ultrafine composite tungsten oxide particles The method for synthesizing ultrafine composite tungsten oxide particles according to the present invention will be described.
Methods for synthesizing the composite tungsten oxide ultrafine particles according to the present invention include a thermal plasma method in which a tungsten compound starting material is introduced into thermal plasma, and a solid phase reaction method in which a tungsten compound starting material is heat-treated in a reducing gas atmosphere. Can be mentioned. Ultrafine composite tungsten oxide particles synthesized by thermal plasma method or solid phase reaction method are subjected to dispersion treatment or pulverization/dispersion treatment.
Hereinafter, (1) thermal plasma method, (2) solid phase reaction method, and (3) synthesized composite tungsten oxide ultrafine particles will be explained in this order.

(1) Thermal plasma method The thermal plasma method will be explained in the following order: (i) raw materials used in the thermal plasma method, and (ii) the thermal plasma method and its conditions.

(i) Raw material used in thermal plasma method When synthesizing the composite tungsten oxide ultrafine particles according to the present invention by a thermal plasma method, a mixed powder of a tungsten compound and an M element compound can be used as a raw material.
Examples of tungsten compounds include tungstic acid (H ₂ WO ₄ ), ammonium tungstate, tungsten hexachloride, tungsten hydrate obtained by adding water to tungsten hexachloride dissolved in alcohol, hydrolyzing it, and then evaporating the solvent. It is preferable that it is one or more types selected from.
Moreover, as the M element compound, it is preferable to use one or more selected from oxides, hydroxides, nitrates, sulfates, chlorides, and carbonates of the M element.

An aqueous solution containing the above-mentioned tungsten compound and the above-mentioned M element compound is prepared such that the ratio of M element to W element is MxWyOz (where M is the M element, W is tungsten, O is oxygen, and 0.001≦x/ Wet mixing is carried out so that the ratio of the M element to the W element is such that y≦1.0, 2.0<z/y≦3.0). Then, by drying the obtained mixed liquid, a mixed powder of the M element compound and the tungsten compound is obtained, and the mixed powder can be used as a raw material for the thermal plasma method.

In addition, the composite tungsten oxide obtained by firing the mixed powder in the first stage in an atmosphere of an inert gas alone or a mixture of an inert gas and a reducing gas is used as a raw material for the thermal plasma method. You can also do that. In addition, in the first stage, the product is fired in a mixed gas atmosphere of an inert gas and a reducing gas, and in the second stage, the fired product is fired in an inert gas atmosphere. The composite tungsten oxide obtained by the stepwise calcination can also be used as a raw material for the thermal plasma method.

(ii) Thermal plasma method and its conditions As the thermal plasma used in the present invention, for example, any one of DC arc plasma, high frequency plasma, microwave plasma, low frequency AC plasma, or a superimposition of these plasmas, or , plasma generated by an electrical method by applying a magnetic field to DC plasma, plasma generated by irradiation with a high-power laser, and plasma generated by a high-power electron beam or ion beam can be applied. Of course, whichever thermal plasma is used, it is preferably a thermal plasma that has a high temperature part of 10,000 to 15,000 K, and in particular, a plasma that can control the generation time of ultrafine particles.

The raw material supplied into the thermal plasma having the high temperature section instantly evaporates in the high temperature section. Then, the evaporated raw material is condensed in the process of reaching the plasma tail flame, and rapidly solidified outside the plasma flame to produce composite tungsten oxide ultrafine particles.

The synthesis method will be described with reference to FIG. 1, taking as an example a case where a high frequency plasma reaction device is used.

First, the inside of the reaction system consisting of the inside of the water-cooled quartz double tube and the inside of the reaction vessel 6 is evacuated to about 0.1 Pa (about 0.001 Torr) using a vacuum evacuation device. After evacuating the inside of the reaction system, the inside of the reaction system is then filled with argon gas to create an argon gas flow system at 1 atm.
Thereafter, a gas selected from argon gas, a mixed gas of argon and helium (Ar-He mixed gas), or a mixed gas of argon and nitrogen (Ar- _N2 mixed gas) is introduced into the reaction vessel as a plasma gas. is introduced at a flow rate of 30 to 45 L/min. On the other hand, an Ar--He mixed gas is introduced at a flow rate of 60 to 70 L/min as a sheath gas to be flowed just outside the plasma region.
Then, alternating current is applied to the high-frequency coil 2 to generate thermal plasma using a high-frequency electromagnetic field (frequency: 4 MHz). At this time, the high frequency power is set to 30 to 40 kW.

Furthermore, from the raw material powder supply nozzle 5, the mixed powder of the M element compound and the tungsten compound obtained by the above synthesis method or the composite tungsten oxide is supplied with 6 to 98 L/min of argon gas supplied from the gas supply device. As a carrier gas, it is introduced into the thermal plasma at a supply rate of 25 to 50 g/min to carry out a reaction for a predetermined period of time. After the reaction, the generated composite tungsten oxide ultrafine particles are deposited on the filter 8 and are collected.

The carrier gas flow rate and raw material supply rate greatly affect the generation time of ultrafine particles. Therefore, it is preferable to set the carrier gas flow rate to 6 L/min or more and 9 L/min or less, and to set the raw material supply rate to 25 to 50 g/min.
Further, it is preferable that the plasma gas flow rate is 30 L/min or more and 45 L/min or less, and the sheath gas flow rate is 60 L/min or more and 70 L/min or less. The plasma gas has the function of maintaining a thermal plasma region having a high temperature part of 10,000 to 15,000 K, and the sheath gas has the function of cooling the inner wall surface of the quartz torch in the reaction vessel and preventing the quartz torch from melting. At the same time, since the plasma gas and sheath gas affect the shape of the plasma region, the flow rates of these gases are important parameters for controlling the shape of the plasma region. As the plasma gas and sheath gas flow rates are increased, the shape of the plasma region extends in the gas flow direction, and the temperature gradient in the plasma tail flame section becomes gentler, which lengthens the generation time of the ultrafine particles and produces ultrafine particles with good crystallinity. will be able to generate. Thereby, the value of the XRD peak top intensity ratio of the composite tungsten oxide ultrafine particles according to the present invention can be set to a desired value. Conversely, as the plasma gas and sheath gas flow rates are lowered, the shape of the plasma region shrinks in the gas flow direction and the temperature gradient in the plasma tail flame region becomes steeper, which shortens the generation time of ultrafine particles and increases the BET ratio. It becomes possible to generate ultrafine particles with a large surface area. Thereby, the value of the ratio of the XRD peak top intensities of the composite tungsten oxide ultrafine particles according to the present invention can be set to a predetermined value.
When the composite tungsten oxide synthesized by the thermal plasma method has a crystallite size exceeding 200 nm, or when the composite tungsten oxide obtained by the thermal plasma method is synthesized, When the dispersed particle size of the composite tungsten oxide exceeds 200 nm, a pulverization/dispersion treatment described below can be performed. When synthesizing a composite tungsten oxide by a thermal plasma method, the plasma conditions and the subsequent pulverization and dispersion treatment conditions are appropriately selected so that the value of the XRD peak top intensity ratio is 0.13 or more. If the difference between the average particle diameter of the composite tungsten oxide ultrafine particles of the composite tungsten oxide ultrafine particle dispersion in the coating of the composite tungsten oxide ultrafine particle dispersion is 20% or less, the present invention can be achieved. The effect is demonstrated.

(2) Solid phase reaction method The solid phase reaction method will be explained in the following order: (i) raw materials used in the solid phase reaction method, (ii) calcination in the solid phase reaction method and its conditions.

(i) Raw materials used in solid phase reaction method When synthesizing the composite tungsten oxide ultrafine particles according to the present invention by solid phase reaction method, a tungsten compound and an M element compound are used as raw materials.
Tungsten compounds include tungstic acid (H ₂ WO ₄ ), ammonium tungstate, tungsten hexachloride, tungsten hydrates obtained by adding water to tungsten hexachloride dissolved in alcohol, hydrolyzing it, and then evaporating the solvent. It is preferable that it is one or more types selected from.
Further, in a more preferred embodiment, the general formula MxWyOz (where M is one or more elements selected from Cs, Rb, K, Tl, and Ba, 0.001≦x/y≦1, 2.0< The M element compounds used to produce the raw material for composite tungsten oxide ultrafine particles represented by z/y≦3.0) include oxides, hydroxides, nitrates, sulfates, chlorides, carbonates, and It is preferable that it is one or more types selected from.
Further, a compound containing one or more impurity elements selected from Si, Al, and Zr (sometimes referred to as an "impurity element compound" in the present invention) may be included as a raw material. The impurity element compound does not react with the composite tungsten compound in the subsequent firing step, suppresses crystal growth of the composite tungsten oxide, and functions to prevent crystal coarsening. The compound containing an impurity element is preferably one or more selected from oxides, hydroxides, nitrates, sulfates, chlorides, and carbonates, and colloidal silica and colloidal alumina with a particle size of 500 nm or less are particularly preferred. preferable.

The tungsten compound and the aqueous solution containing the M element compound are prepared such that the ratio of M element to W element is MxWyOz (where M is the M element, W is tungsten, O is oxygen, 0.001≦x/y≦ Wet mixing is performed so that the ratio of M element to W element is 1.0, 2.0<z/y≦3.0). When containing an impurity element compound as a raw material, wet mixing is performed so that the impurity element compound is 0.5% by mass or less. Then, by drying the obtained liquid mixture, a mixed powder of an M element compound and a tungsten compound, or a mixed powder of an M element compound and a tungsten compound containing an impurity element compound is obtained.

(ii) Firing in the solid phase reaction method and its conditions A mixed powder of an M element compound and a tungsten compound produced by the wet mixing, or a mixed powder of an M element compound and a tungsten compound containing an impurity element compound, is Firing is performed in one step in an atmosphere of an active gas alone or a mixed gas of an inert gas and a reducing gas. At this time, the firing temperature is preferably close to the temperature at which the composite tungsten oxide ultrafine particles begin to crystallize. Specifically, the firing temperature is preferably 1000°C or lower, more preferably 800°C or lower, and 800°C or lower. A temperature range of 500°C or lower is more preferable. By controlling this firing temperature, the value of the ratio of the XRD peak top intensities of the composite tungsten oxide ultrafine particles according to the present invention can be set to a predetermined value.
Of course, in the synthesis of the composite tungsten oxide ultrafine particles, tungsten trioxide may be used instead of the tungsten compound.

(3) Synthesized composite tungsten oxide ultrafine particles A composite tungsten oxide ultrafine particle dispersion described below was prepared using composite tungsten oxide ultrafine particles obtained by a synthesis method using thermal plasma method or solid phase reaction method. In this case, if the dispersed particle size of the ultrafine particles contained in the dispersion liquid exceeds 200 nm, it may be pulverized and dispersed in the process of producing a composite tungsten oxide ultrafine particle dispersion liquid described later. If the value of the ratio of the XRD peak top intensity of the composite tungsten oxide ultrafine particles obtained through the pulverization and dispersion treatment is within the range of the present invention, then the composite tungsten oxide ultrafine particles according to the present invention The composite tungsten oxide ultrafine particle dispersion obtained from the dispersion can realize excellent near-infrared absorption characteristics.

[c] Volatile components of composite tungsten oxide ultrafine particles and method for drying the same As described above, the composite tungsten oxide ultrafine particles according to the present invention may contain volatile components, but the content of the volatile components is It is preferably 2.5% by mass or less. However, if the composite tungsten oxide ultrafine particles are exposed to the atmosphere and the volatile component content exceeds 2.5% by mass, it is not possible to reduce the volatile component content by drying. I can do it.
Specifically, the composite tungsten oxide synthesized by the method described above is pulverized and dispersed into fine particles to produce a composite tungsten oxide ultrafine particle dispersion (pulverization/dispersion treatment process), and the manufactured tungsten oxide is The composite tungsten oxide ultrafine particles according to the present invention can be produced by drying the composite tungsten oxide ultrafine particle dispersion to remove the solvent (drying step).

Since the pulverization and dispersion process will be described in detail in the section "[d] Composite tungsten oxide ultrafine particle dispersion" described later, the drying process will be described here.
In the drying process, the composite tungsten oxide ultrafine particle dispersion obtained in the pulverization and dispersion process described below is dried to remove volatile components in the dispersion, thereby producing the composite tungsten oxide ultrafine particles according to the present invention. This is what you get.

Equipment for drying treatment includes an atmospheric dryer, universal mixer, ribbon mixer, vacuum fluidized fluid dryer, and vibratory fluidized fluid dryer, as they are capable of heating and/or depressurizing, and are easy to mix and collect the ultrafine particles. Dryers, freeze dryers, ribocones, rotary kilns, spray dryers, parcon dryers, etc. are preferred, but are not limited to these.
Hereinafter, as examples thereof, (1) a drying process using an atmospheric dryer, (2) a drying process using a vacuum fluidized dryer, and (3) a drying process using a spray dryer will be described. Hereinafter, each drying process will be explained in order.

(1) Drying treatment using an atmospheric dryer This is a treatment method in which a composite tungsten oxide ultrafine particle dispersion obtained by the method described below is dried using an atmospheric dryer to remove volatile components in the dispersion. In this case, it is desirable to perform the drying treatment at a temperature higher than that at which the volatile component is volatilized from the composite tungsten oxide ultrafine particles and at which element M is not desorbed, and preferably at a temperature of 150° C. or lower.
The composite tungsten oxide ultrafine particles produced by drying in the atmospheric dryer are weak secondary aggregates. Even in this state, it is possible to disperse the composite tungsten oxide ultrafine particles in resin, etc., but it is also preferable to crush the ultrafine particles using a crusher or the like in order to make the dispersion easier. .

(2) Drying treatment using a vacuum fluidized dryer This is a treatment method for removing volatile components in a composite tungsten oxide ultrafine particle dispersion by performing a drying treatment using a vacuum fluidized dryer. In the vacuum fluidized dryer, drying and crushing are performed simultaneously in a reduced pressure atmosphere, so the drying speed is fast and aggregates are not formed as seen in the products dried in the above-mentioned atmospheric dryer. Furthermore, since drying is performed under a reduced pressure atmosphere, volatile components can be removed even at relatively low temperatures, and the amount of remaining volatile components can be minimized.
The drying temperature is preferably a temperature at which the element M is not desorbed from the composite tungsten oxide ultrafine particles, and is preferably higher than the temperature at which the volatile components are volatilized, and is preferably 150° C. or lower.

(3) Drying treatment using a spray dryer This is a treatment method in which volatile components of the composite tungsten oxide ultrafine particle dispersion are removed by performing a drying treatment using a spray dryer. With this spray dryer, secondary agglomeration due to the surface force of volatile components is less likely to occur when volatile components are removed during drying, and composite tungsten oxide is produced that is relatively free of secondary agglomeration even without crushing. Ultrafine particles are obtained.

By dispersing the composite tungsten oxide ultrafine particles that have been subjected to the drying treatment according to (1) to (3) above in a resin etc. by an appropriate method, high visible light transmittance and near-infrared absorption function can be achieved. It is possible to form a composite tungsten oxide ultrafine particle dispersion, which is a near-infrared absorbing material fine particle dispersion that has optical properties such as low solar transmittance and a low haze value.

[d] Composite tungsten oxide ultrafine particle dispersion A composite tungsten oxide ultrafine particle dispersion for producing near-infrared absorbing fibers will be described.
The composite tungsten oxide ultrafine particle dispersion is made from the composite tungsten oxide ultrafine particles obtained by the above synthesis method, water, an organic solvent, a liquid resin, a liquid plasticizer for plastics, a polymer monomer, or a mixture thereof. The liquid medium of the selected mixed slurry and appropriate amounts of a dispersant, a coupling agent, a surfactant, etc. are pulverized and dispersed in a media stirring mill.
Further, it is characterized in that the fine particles are well dispersed in the solvent and have a dispersed particle diameter of 1 to 200 nm. Further, the content of the composite tungsten oxide ultrafine particles contained in the composite tungsten oxide ultrafine particle dispersion is preferably 0.01% by mass or more and 80% by mass or less.
Below, regarding the composite tungsten oxide ultrafine particle dispersion according to the present invention, (1) solvent, (2) dispersant, (3) dispersion method, (4) dispersed particle size, (5) binder, other additives, I will explain in this order.

(1) Solvent The liquid solvent used for the composite tungsten oxide ultrafine particle dispersion is not particularly limited, and depends on the coating conditions and coating environment of the composite tungsten oxide ultrafine particle dispersion, as well as the inorganic binder and the like that are added as appropriate. It may be selected appropriately depending on the resin binder and the like. For example, the liquid solvent is water, an organic solvent, an oil or fat, a liquid resin, a liquid plasticizer for a medium resin, a polymer monomer, or a mixture thereof.

Here, various organic solvents can be selected, such as alcohol-based, ketone-based, hydrocarbon-based, glycol-based, and water-based. Specifically, alcohol solvents such as methanol, ethanol, 1-propanol, isopropanol, butanol, pentanol, benzyl alcohol, and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; Ester solvents such as 3-methyl-methoxy-propionate; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol isopropyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol methyl ether acetate, propylene Glycol derivatives such as glycol ethyl ether acetate; amides such as formamide, N-methylformamide, dimethylformamide, dimethylacetamide, and N-methyl-2-pyrrolidone; aromatic hydrocarbons such as toluene and xylene; ethylene chloride, Chlorbenzene and the like can be used. Among these organic solvents, dimethyl ketone, methyl ethyl ketone, methyl isobutyl ketone, toluene, propylene glycol monomethyl ether acetate, n-butyl acetate and the like are particularly preferred.

The oil is preferably a vegetable oil or a vegetable-derived oil. Vegetable oils include drying oils such as linseed oil, sunflower oil, tung oil, and eno oil; semi-drying oils such as sesame oil, cottonseed oil, rapeseed oil, soybean oil, rice bran oil, and poppy oil; olive oil, coconut oil, palm oil, and dehydrated castor oil. Non-drying oils such as As compounds derived from vegetable oils, fatty acid monoesters and ethers, which are obtained by directly esterifying fatty acids of vegetable oils and monoalcohols, are used. In addition, commercially available petroleum solvents can also be used as fats and oils, such as Isopar E, Exol Hexane, Exol Heptane, Exol E, Exol D30, Exol D40, Exol D60, Exol D80, Exol D95, Exol D110, Exol D130 (the above, (manufactured by ExxonMobil), etc.

As the liquid plasticizer for the medium resin, known liquid plasticizers typified by organic acid esters, phosphate esters, and the like can be used.

Here, the liquid plasticizer includes, for example, a plasticizer that is a compound of a monohydric alcohol and an organic acid ester, an ester plasticizer such as a polyhydric alcohol organic acid ester compound, an organic phosphate plasticizer, etc. Examples include phosphoric acid-based plasticizers, and those that are liquid at room temperature are preferred. Among these, plasticizers that are ester compounds synthesized from polyhydric alcohols and fatty acids are preferred.

Ester compounds synthesized from polyhydric alcohols and fatty acids are not particularly limited, but include glycols such as triethylene glycol, tetraethylene glycol, and tripropylene glycol, and butyric acid, isobutyric acid, caproic acid, 2-ethylbutyric acid, and heptylic acid. Examples include glycol-based ester compounds obtained by reaction with monobasic organic acids such as , n-octylic acid, 2-ethylhexylic acid, pelargonic acid (n-nonylic acid), and decylic acid. Also included are ester compounds of tetraethylene glycol, tripropylene glycol, and the above-mentioned monobasic organic compounds.
Among them, fatty acid esters of triethylene glycol such as triethylene glycol dihexanate, triethylene glycol di-2-ethyl butyrate, triethylene glycol di-octanate, and triethylene glycol di-2-ethyl hexanoate are preferred. be.

Furthermore, a polymer monomer is a monomer that forms a polymer through polymerization, etc., and preferred polymer monomers used in the present invention include methyl methacrylate monomer, acrylate monomer, and styrene resin. Examples include monomers.

The liquid solvents described above can be used alone or in combination of two or more. Furthermore, if necessary, an acid or alkali may be added to these liquid solvents to adjust the pH.

(2) Dispersant Furthermore, in order to further improve the dispersion stability of the composite tungsten oxide ultrafine particles in the composite tungsten oxide ultrafine particle dispersion and to avoid coarsening of the dispersed particle size due to re-agglomeration, various It is also preferable to add dispersants, surfactants, coupling agents, and the like. The dispersant, coupling agent, and surfactant can be selected depending on the intended use, but preferably have an amine-containing group, a hydroxyl group, a carboxyl group, or an epoxy group as a functional group. These functional groups are adsorbed onto the surface of the composite tungsten oxide ultrafine particles to prevent agglomeration, and have the effect of uniformly dispersing the composite tungsten oxide ultrafine particles according to the present invention even in the infrared absorbing film. A polymeric dispersant having any of these functional groups in its molecule is more desirable.

Preferred specific examples of commercially available dispersants include SOLSPERSE3000, SOLSPERSE9000, SOLSPERSE11200, SOLSPERSE13000, SOLSPERSE13240, SOLSPERSE13650, and SOLSPERSE13940 manufactured by Nippon Lubrizol Co., Ltd. , SOLSPERSE16000, SOLSPERSE17000, SOLSPERSE18000, SOLSPERSE20000, SOLSPERSE21000, SOLSPERSE24000SC, SOLSPERSE24000GR, SOLSPERSE2600 0, SOLSPERSE27000, SOLSPERSE28000, SOLSPERSE31845, SOLSPERSE32000, SOLSPERSE32500, SOLSPERSE32550, SOLSPERSE32600, SOLSPERSE33000, SOLSPERSE33500, S OLSPERSE34750, SOLSPERSE35100, SOLSPERSE35200, SOLSPERSE36600, SOLSPERSE37500, SOLSPERSE38500, SOLSPERSE39000, SOLSPERSE41000, SOLS PERSE41090, SOLSPERSE53095, SOLSPERSE55000, SOLSPERSE56000, SOLSPERSE76500, etc.;
Disperbyk-101, Disperbyk-103, Disperbyk-107, Disperbyk-108, Disperbyk-109, Disperbyk-110, Disperbyk-111, Disperbyk-112 manufactured by Big Chemie Japan Co., Ltd. , Disperbyk-116, Disperbyk-130, Disperbyk-140 , Disperbyk-142, Disperbyk-145, Disperbyk-154, Disperbyk-161, Disperbyk-162, Disperbyk-163, Disperbyk-164, Disperbyk-165, Disperby k-166, Disperbyk-167, Disperbyk-168, Disperbyk-170, Disperbyk -171, Disperbyk-174, Disperbyk-180, Disperbyk-181, Disperbyk-182, Disperbyk-183, Disperbyk-184, Disperbyk-185, Disperbyk-190, Disp erbyk-2000, Disperbyk-2001, Disperbyk-2020, Disperbyk-2025 , Disperbyk-2050, Disperbyk-2070, Disperbyk-2095, Disperbyk-2150, Disperbyk-2155, Anti-Terra-U, Anti-Terra-203, Anti-Terra-204, BY K-P104, BYK-P104S, BYK-220S , BYK-6919, etc.;
Manufactured by BASF Japan Co., Ltd. EFKA4008, EFKA4046, EFKA4047, EFKA4015, EFKA4020, EFKA4050, EFKA4055, EFKA4060, EFKA4080, EFKA4300, EFKA4330, EFKA4400, E FKA4401, EFKA4402, EFKA4403, EFKA4500, EFKA4510, EFKA4530, EFKA4550, EFKA4560, EFKA4585, EFKA4800 , EFKA5220, EFKA6230, JONCRYL67, JONCRYL678, JONCRYL586, JONCRYL611, JONCRYL680, JONCRYL682, JONCRYL690, JONCRYL819, JONCRYL-JDX5050 etc;
Examples include Ajisper PB-711, Ajisper PB-821, and Ajisper PB-822 manufactured by Ajinomoto Fine-Techno, Inc.

(3) Dispersion method The method for dispersing the composite tungsten oxide ultrafine particles into the dispersion liquid is not particularly limited as long as the fine particles can be uniformly dispersed in the dispersion liquid without agglomeration. Examples of the dispersion method include a pulverization and dispersion treatment method using a device such as a bead mill, a ball mill, a sand mill, a paint shaker, and an ultrasonic homogenizer. Among these, pulverization and dispersion using media such as beads, balls, and Ottawa sand using a media agitation mill such as a bead mill, ball mill, sand mill, or paint shaker is preferable because it takes less time to reach the desired dispersed particle size. .
Through pulverization and dispersion treatment using a media agitation mill, ultrafine composite tungsten oxide particles are dispersed into the dispersion liquid, and at the same time, ultrafine composite tungsten oxide particles collide with each other and the medium collides with the ultrafine particles, resulting in fine particles. The process progresses, and the composite tungsten oxide ultrafine particles can be made into finer particles and dispersed (that is, they are subjected to pulverization and dispersion treatment).
At this time, in pulverizing and dispersing the composite tungsten oxide ultrafine particles, when the value of the XRD peak intensity of the (220) plane of the silicon powder standard sample (manufactured by NIST, 640c) is set to 1, the composite tungsten oxide ultrafine particles The process conditions for pulverization and dispersion are set so that the ratio of the XRD peak top intensities of 0.13 or more can be ensured. With this setting, the near-infrared absorbing fiber containing the composite tungsten oxide ultrafine particles exhibits excellent optical properties.

When dispersing the composite tungsten oxide ultrafine particles in a plasticizer, it is also preferable to further add an organic solvent having a boiling point of 120° C. or lower, if desired.
Specific examples of the organic solvent having a boiling point of 120°C or lower include toluene, methyl ethyl ketone, methyl isobutyl ketone, butyl acetate, isopropyl alcohol, and ethanol. Of course, any material can be selected as long as it can uniformly disperse fine particles having a boiling point of 120° C. or less and exhibiting a near-infrared absorbing function. However, when the organic solvent is added, a drying step is carried out after the dispersion is completed, and the organic solvent remaining in the near-infrared absorbing interlayer film, which will be described later as an example of a near-infrared absorbing ultrafine particle dispersion, is 5% by mass or less. It is preferable to do so.

(4) Dispersed particle size If the dispersed particle size of the composite tungsten oxide ultrafine particles is 1 to 200 nm, light in the visible light range of wavelengths 380 nm to 780 nm will not be scattered due to geometric scattering or Mie scattering. This is preferable because haze can be reduced and visible light transmittance can be increased. Furthermore, in the Rayleigh scattering region, scattered light is reduced in proportion to the sixth power of the particle size, so as the dispersed particle size decreases, scattering decreases and transparency improves. Therefore, it is preferable that the dispersed particle size is 200 nm or less, since the amount of scattered light will be very small and the blue haze phenomenon can be suppressed, thereby further increasing transparency.

Here, the dispersed particle diameter of the composite tungsten oxide ultrafine particles in the composite tungsten oxide ultrafine particle dispersion will be briefly explained. The dispersed particle size of ultrafine composite tungsten oxide particles refers to the particle size of single particles of ultrafine composite tungsten oxide particles dispersed in a solvent or aggregated particles of the ultrafine composite tungsten oxide particles. It can be measured using various commercially available particle size distribution analyzers. For example, a sample of the composite tungsten oxide ultrafine particle dispersion can be collected and measured using ELS-8000 manufactured by Otsuka Electronics Co., Ltd., which is based on the dynamic light scattering method.

Further, a composite tungsten oxide ultrafine particle dispersion in which the content of composite tungsten oxide ultrafine particles obtained by the above synthesis method is 0.01% by mass or more and 80% by mass or less has excellent liquid stability. If an appropriate liquid medium, dispersant, coupling agent, and surfactant are selected, the dispersion will not gel or the particles will settle for more than 6 months even when placed in a constant temperature bath at a temperature of 40°C. The dispersed particle size can be maintained within the range of 1 to 200 nm.
Note that the dispersed particle diameter of the composite tungsten oxide ultrafine particle dispersion may differ from the average particle diameter of the composite tungsten oxide ultrafine particles dispersed in the threads or the like constituting the near-infrared absorbing fiber. This is because the composite tungsten oxide ultrafine particles may be aggregated in the composite tungsten oxide ultrafine particle dispersion, while the near-infrared absorbing fiber is constructed using the composite tungsten oxide ultrafine particle dispersion This is because the agglomeration of the composite tungsten oxide ultrafine particles is resolved when the thread or the like is manufactured and processed.

(5) Binder and other additives The composite tungsten oxide ultrafine particle dispersion may contain one or more resin binders as appropriate. The type of resin binder contained in the composite tungsten oxide ultrafine particle dispersion is not particularly limited, but the resin binder may be a raw material polymer for the near-infrared absorbing fiber, or may be compatible with the raw material polymer. Thermoplastic resins such as acrylic resins, thermosetting resins such as epoxy resins, etc. can be used.

In addition, in order to improve the near-infrared absorption characteristics of the composite tungsten oxide ultrafine particle dispersion according to the present invention, the dispersion according to the present invention may be added to the general formula XBm (where X is an alkaline earth element or a rare earth element containing yttrium). It is also a preferable configuration to appropriately add near-infrared absorbing ultrafine particles such as a metal element selected from the elements, a boride represented by 4≦m≦6.3, ATO, and ITO, as desired. Note that the addition ratio at this time may be appropriately selected depending on the desired near-infrared absorption characteristics.
Further, in order to adjust the color tone of the composite tungsten oxide ultrafine particle dispersion, known inorganic pigments such as carbon black and Bengara, and known organic pigments can also be added.
A known ultraviolet absorber, a known organic infrared absorber, or a phosphorus coloring inhibitor may be added to the composite tungsten oxide ultrafine particle dispersion.
Furthermore, fine particles having the ability to emit far infrared rays may be added. For example, metal oxides such as ZrO ₂ , SiO ₂ , TiO ₂ , Al ₂ O ₃ , MnO ₂ , MgO, Fe ₂ O ₃ , CuO, etc., carbides such as ZrC, SiC, TiC, ZrN, Si ₃ N ₄ , AlN Examples include nitrides such as.

[2] Near-infrared absorbing fiber The near-infrared absorbing fiber according to the present invention will be explained.
The near-infrared absorbing fiber is obtained by dispersing the composite tungsten oxide ultrafine particles obtained by the above-mentioned synthesis method in an appropriate medium, and containing the dispersion on the surface and/or inside the fiber.
The content of the composite tungsten oxide ultrafine particles is 0.001% by mass or more and 80% by mass or less based on the solid content of the fiber.
Hereinafter, the near-infrared absorbing fiber according to the present invention will be explained in the following order: (1) fiber, (2) method for dispersing ultrafine particles into the fiber, and (3) additive.
(1) Fiber

The fibers used in the present invention can be selected from various types depending on the purpose, and include synthetic fibers, semi-synthetic fibers, natural fibers, recycled fibers, inorganic fibers, or mixed yarns such as blends, doublings, and mixed fibers of these fibers. It doesn't matter which one you use. Furthermore, synthetic fibers are preferable in view of incorporating ultrafine composite tungsten oxide particles into fibers in a simple manner and maintaining heat retention.

The synthetic fibers used in the present invention are not particularly limited, but include, for example, polyurethane fibers, polyamide fibers, acrylic fibers, polyester fibers, polyolefin fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, and polyvinyl chloride fibers. Examples include polyester fibers, polyetherester fibers, and the like.

Examples of polyamide fibers include nylon, nylon 6, nylon 66, nylon 11, nylon 610, nylon 612, aromatic nylon, and aramid.
Further, examples of acrylic fibers include polyacrylonitrile, acrylonitrile-vinyl chloride copolymer, modacrylic, and the like.
Further, examples of polyester fibers include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polyethylene naphthalate.
Furthermore, examples of polyolefin fibers include polyethylene, polypropylene, polystyrene, and the like.
Further, examples of polyvinyl alcohol fibers include vinylon and the like.
Furthermore, examples of polyvinylidene chloride fibers include vinylidene and the like.
Furthermore, examples of polyvinyl chloride fiber include polyvinyl chloride.
Further, examples of polyetherester fibers include Lexe and Success.
When the fiber used in the present invention is a semi-synthetic fiber, examples thereof include cellulose fiber, protein fiber, chlorinated rubber, hydrochloric acid rubber, and the like.
Further, for example, cellulose fibers include acetate, triacetate, oxidized acetate, and the like.
Further, for example, protein fibers include Promix and the like.
When the fiber used in the present invention is a natural fiber, examples thereof include vegetable fiber, animal fiber, mineral fiber, and the like.
Further, examples of the plant fibers include cotton, kapok, flax, hemp, jute, Manila hemp, sisal hemp, New Zealand hemp, Rabun hemp, palm, rush, and wheat straw.
Examples of animal fibers include wools such as wool, goat hair, mohair, cashmere, alpaca, angora, camel, and vicuña, silk, down, and feathers.
Further, examples of mineral fibers include asbestos and asbestos.
When the fiber used in the present invention is a regenerated fiber, examples thereof include cellulose fiber, protein fiber, algin fiber, rubber fiber, chitin fiber, mannan fiber, and the like.
For example, cellulose fibers include rayon, viscose rayon, cupro, polynosic, cuprammonium rayon, and the like.
Further, examples of the protein fiber include casein fiber, peanut protein fiber, corn protein fiber, soybean protein fiber, and regenerated silk thread.
When the fibers used in the present invention are inorganic fibers, examples thereof include metal fibers, carbon fibers, silicate fibers, and the like.
Further, examples of the metal fibers include metal fibers, gold threads, silver threads, heat-resistant alloy fibers, and the like.
Furthermore, examples of silicate fibers include glass fibers, mineral slag fibers, rock fibers, and the like.

The cross-sectional shape of the fiber according to the present invention is not particularly limited, but examples thereof include circular, triangular, hollow, flattened, Y-shaped, star-shaped, core-sheath shape, and the like. The inclusion of ultrafine particles on the surface and/or inside of the fiber is possible in various shapes; for example, in the case of a core-sheath type, ultrafine particles may be contained in the core of the fiber or in the sheath. I don't mind. Further, the shape of the fibers of the present invention may be filaments (long fibers) or staples (short fibers).

(2) Method for dispersing ultrafine particles into fibers The method for uniformly incorporating ultrafine composite tungsten oxide particles into the surface and/or inside of the fibers according to the present invention is not particularly limited. For example, (a) a method in which ultrafine composite tungsten oxide particles are directly mixed into a raw material polymer for synthetic fibers and then spun; (b) a method in which the ultrafine composite tungsten oxide particles are included in a part of the raw material polymer in advance at a high concentration; (c) The composite tungsten oxide ultrafine particles are uniformly dispersed in a raw material monomer or oligomer solution in advance. , a method in which the desired raw material polymer is synthesized using this dispersion solution, and at the same time, the composite tungsten oxide ultrafine particles are uniformly dispersed in the raw material polymer, and then spun; Examples include a method of attaching the composite tungsten oxide ultrafine particles to the surface of the fiber using a binder or the like.

Here, a preferred example of the method described in (b), in which a masterbatch is produced, diluted and adjusted during spinning, and then spun will be described in more detail.
The method for producing the masterbatch is not particularly limited, but for example, a composite tungsten oxide ultrafine particle dispersion, thermoplastic resin powder or pellets, and other additives as necessary are mixed in a rib blender or a tumbler. The solvent is removed using mixers such as Nauta mixer, Henschel mixer, super mixer, planetary mixer, etc., and kneading machines such as Banbury mixer, kneader, roll, kneader-ruder, single screw extruder, twin screw extruder, etc. By uniformly melting and mixing the thermoplastic resin, a masterbatch can be prepared as a mixture in which ultrafine particles are uniformly dispersed in the thermoplastic resin.

Furthermore, after preparing the composite tungsten oxide ultrafine particle dispersion, the solvent of the dispersion is removed by a known method, and the obtained powder, thermoplastic resin powder or pellets, and other It is also possible to produce a mixture in which the ultrafine particles are uniformly dispersed in a thermoplastic resin by uniformly melt-mixing the additives. In addition, it is also possible to use a method in which the powder of composite tungsten oxide ultrafine particles is directly added to the thermoplastic resin and uniformly melted and mixed.

A mixture of the composite tungsten oxide ultrafine particles obtained by the method described above and a thermoplastic resin is kneaded in a pent-type single-screw or twin-screw extruder and processed into pellets to produce a near-infrared absorbing component-containing master. You can get a batch.

Here, methods (a) to (d) for uniformly containing composite tungsten oxide ultrafine particles in the fibers used in the present invention described above will be explained with specific examples.
Method (a): For example, when using polyester fiber as the fiber, a composite tungsten oxide ultrafine particle dispersion is added to polyethylene terephthalate resin pellets, which is a thermoplastic resin, and the mixture is uniformly mixed in a blender, and then the solvent is removed. . The mixture from which the solvent has been removed is melt-kneaded using a twin-screw extruder to obtain a masterbatch containing ultrafine composite tungsten oxide particles. This composite tungsten oxide ultrafine particle-containing masterbatch and a target amount of a masterbatch made of polyethylene terephthalate without the addition of ultrafine particles are melt-mixed at around the melting temperature of the resin and spun according to a known method.

Method (b): In the same manner as in (a) except for using the masterbatch containing composite tungsten oxide ultrafine particles prepared in advance, a masterbatch containing composite tungsten oxide ultrafine particles and a masterbatch containing no ultrafine particles were used. A target amount of a masterbatch made of polyethylene terephthalate is melt-mixed at around the melting temperature of the resin, and spun according to a known method.

Method (c): For example, when using urethane fibers as fibers, a polymeric diol containing ultrafine composite tungsten oxide particles and an organic diisocyanate are reacted in a twin-screw extruder to synthesize an isocyanate group-terminated prepolymer. Thereafter, a chain extender is reacted thereto to produce a polyurethane solution (raw material polymer). The polyurethane solution is spun according to a known method.

Method (d): For example, in order to attach composite tungsten oxide ultrafine particles to the surface of natural fibers, first, composite tungsten oxide ultrafine particles and at least one type of compound selected from acrylic, epoxy, urethane, and polyester are used. A processing liquid is prepared by mixing a binder resin and a solvent such as water. Next, by immersing the natural fiber in the prepared treatment liquid, or by impregnating the natural fiber with the prepared treatment liquid by padding, printing, spraying, etc., and drying, the composite tungsten oxide is applied to the natural fiber. Ultrafine particles can be attached. In addition to the above-mentioned natural fibers, the method (d) can be applied to any of semi-synthetic fibers, regenerated fibers, inorganic fibers, blends, yarns, mixed fibers, etc. thereof.

In addition, when carrying out the above-mentioned methods (a) to (d), the dispersion method of the composite tungsten oxide ultrafine particles may be any method as long as the composite tungsten oxide ultrafine particles can be uniformly dispersed in the liquid. Any method may be used, and for example, methods such as a medium stirring mill, a ball mill, a sand mill, and ultrasonic dispersion can be suitably applied.
In the dispersion of the composite tungsten oxide ultrafine particles, when the XRD peak intensity value of the (220) plane of the silicon powder standard sample (manufactured by NIST, 640c) is set to 1, the XRD peak top of the composite tungsten oxide ultrafine particles The dispersion process conditions are set so that the intensity ratio value is 0.13 or more. By doing so, the near-infrared absorbing fiber according to the present invention exhibits excellent optical properties.

Further, the dispersion medium for the composite tungsten oxide ultrafine particles is not particularly limited, and can be selected depending on the fibers to be mixed. Various organic solvents and water can be used.

Furthermore, when adhering and mixing the composite tungsten oxide ultrafine particles to the fiber or the polymer that is its raw material, the dispersion liquid of the composite tungsten oxide ultrafine particle is directly mixed with the fiber or the polymer that is its raw material. I don't mind. In addition, if necessary, an acid or alkali may be added to the dispersion liquid of composite tungsten oxide ultrafine particles to adjust the pH, and various surfactants may be added to further improve the dispersion stability of the ultrafine particles. It is also preferable to add a coupling agent or the like.

Here, the content of the composite tungsten oxide ultrafine particles will be explained. Since the composite tungsten oxide ultrafine particles according to the present invention have a very high near-infrared absorbing ability per unit weight, they exhibit their effect with a usage amount of about 4 to 10 times lower than that of ITO or ATO. Specifically, the content of the composite tungsten oxide ultrafine particles contained on the surface and/or inside of the fiber is between 0.001% by mass and 80% by mass based on the solid content of the fiber. It is preferable. Furthermore, when considering the weight of the fiber after addition of fine particles and the cost of raw materials, it is preferable to select between 0.005% by mass and 50% by mass. If the usage amount is 0.001% by mass or more, sufficient near-infrared absorption effect can be obtained even if the fabric is thin, and if it is 80% by mass or less, filter clogging or thread breakage may occur during the spinning process. It is more preferable that the amount is 50% by mass or less, since the decrease in spinnability due to the above can be avoided. Furthermore, since the amount of ultrafine particles added is small, the physical properties of the fibers are not impaired.

(3) Additives In addition, depending on the purpose, antioxidants, flame retardants, deodorants, insect repellents, antibacterial agents, ultraviolet absorbers, and It can be used by containing agents, etc.

Furthermore, in addition to the near-infrared absorbing material according to the present invention, fine particles of a far-infrared emitting substance capable of emitting far-infrared rays may be contained on the surface and/or inside the fiber. For example, metal oxides such as ZrO ₂ , SiO ₂ , TiO ₂ , Al ₂ O ₃ , MnO ₂ , MgO, Fe ₂ O ₃ , CuO, etc., carbides such as ZrC, SiC, TiC, ZrN, Si ₃ N ₄ , AlN Examples include nitrides such as.
The composite tungsten oxide ultrafine particles, which are the near-infrared absorbing material according to the present invention, have the property of absorbing solar energy in the wavelength range of 0.3 to 3 μm, especially in the wavelength range of around 0.9 to 2.2 μm. It selectively absorbs near-infrared light and converts it into heat or re-radiates it. On the other hand, far-infrared emitting material particles have the ability to receive the energy absorbed by composite tungsten oxide ultrafine particles, which are near-infrared absorbing materials, and convert the energy into thermal energy at mid- and far-infrared wavelengths and radiate it. There is. For example, ZrO ₂ fine particles convert this energy into thermal energy with a wavelength of 2 to 20 μm and radiate it. Therefore, when the fine particles that have the ability to emit far infrared rays coexist with the fine particles that emit far infrared rays in the composite tungsten oxide ultrafine particles in the fibers and on the surface, the sunlight energy absorbed by the near infrared absorbing material is absorbed. It is efficiently consumed inside and on the surface of the fibers, resulting in more effective heat retention.

Further, the content of fine particles of the far-infrared emitting substance on the fiber surface and/or inside the fiber is preferably between 0.001% by mass and 80% by mass based on the solid content of the fiber. If it is used in an amount of 0.001% by mass or more, sufficient thermal energy radiation effect can be obtained even if the fabric is thin, and if it is less than 80% by mass, it may clog the filter or break the yarn during the spinning process. It is possible to avoid a decrease in spinnability.

As explained above, the near-infrared-absorbing fiber according to the present invention uniformly contains composite tungsten oxide ultrafine particles as a near-infrared-absorbing component, and furthermore, the near-infrared ray-absorbing fiber evenly contains fine particles that emit far-infrared rays. By including a small amount of the fine particles, it is possible to efficiently absorb near-infrared rays from sunlight, etc., and provide fibers with excellent heat retention even with a small amount of composite tungsten oxide ultrafine particles added. And so. In addition, it has good weather resistance, excellent transparency, and low cost, and because the amount of composite tungsten oxide ultrafine particles added is small, it does not impair the design of textile products and improves the basic properties of fibers such as strength and elongation. It was also possible to avoid deterioration of physical properties. As a result, the fibers according to the present invention can be used in various applications such as textile products such as cold-weather clothing, sports clothing, stockings, curtains, etc. that require heat retention, and other industrial textile products.

The present invention will be specifically described below with reference to Examples. However, the present invention is not limited to the following examples.
The optical properties of the dispersions and coating films in Examples and Comparative Examples were measured using a spectrophotometer (U-4100 manufactured by Hitachi, Ltd.), and the visible light transmittance and solar transmittance were determined according to JISR3106. Calculated. Further, the dispersed particle diameter was expressed as an average value measured using a particle diameter measuring device based on a dynamic light scattering method (ELS-8000, manufactured by Otsuka Electronics Co., Ltd.).
In addition, the content of volatile components in Examples and Comparative Examples was determined by using a moisture meter MOC63u manufactured by Shimadzu Corporation, and heating the measurement sample from room temperature to 125°C in 1 minute from the start of measurement. It was held for 9 minutes. The weight loss rate of the measurement sample 10 minutes after the start of the measurement was defined as the volatile component content. The average particle diameter of the composite tungsten oxide ultrafine particles dispersed in the near-infrared absorbing material fine particle dispersion or in the solar radiation absorbing interlayer film can be determined by observing a transmission electron microscope image of a cross section of the dispersion or interlayer film. It was measured by Transmission electron microscope images were observed using a transmission electron microscope (HF-2200, manufactured by Hitachi High-Technologies Corporation). The transmission electron microscope image was processed with an image processing device, and the particle size of 100 composite tungsten oxide ultrafine particles was measured, and the average value was taken as the average particle size. The X-ray diffraction pattern was measured by powder X-ray diffraction method (θ-2θ method) using a powder X-ray diffraction device (X'Pert-PRO/MPD manufactured by PANalytical, Spectris Co., Ltd.). In addition, in order to ensure objective quantitative performance, each time the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles is measured, the X-ray diffraction pattern of the silicon powder standard sample is measured, and the peak intensity ratio is calculated each time. Calculated.

[Example 1]
Dissolve 0.216 kg of Cs ₂ CO ₃ in 0.330 kg of water, add this to 1.000 kg of H ₂ WO ₄ and stir thoroughly, then dry to obtain a Cs _0.33 WO ₃ mixed powder with the desired composition. I got a body.

Next, using the high-frequency plasma reaction apparatus explained in FIG. 1, the inside of the reaction system was evacuated to about 0.1 Pa (about 0.001 Torr) using a vacuum evacuation device, and then completely replaced with argon gas to 1 atm. distribution system. Thereafter, argon gas was introduced into the reaction vessel as a plasma gas at a flow rate of 30 L/min, and as a sheath gas, argon gas was introduced spirally from the sheath gas supply port at a flow rate of 55 L/min and helium gas was introduced at a flow rate of 5 L/min. Then, high-frequency power was applied to a water-cooled copper coil for high-frequency plasma generation to generate high-frequency plasma. At this time, the high frequency power was set to 40 kW in order to generate thermal plasma having a high temperature part of 10,000 to 15,000 K.

After generating high-frequency plasma in this manner, the mixed powder was supplied into the thermal plasma at a rate of 50 g/min while argon gas was supplied as a carrier gas from a gas supply device at a flow rate of 9 L/min.
As a result, the mixed powder was instantaneously evaporated in the thermal plasma, rapidly solidified in the process of reaching the plasma tail flame, and became ultra-fine. The generated ultrafine particles were deposited on the collection filter.

The deposited ultrafine particles were collected, and the X-ray diffraction pattern was measured by powder X-ray diffraction method (θ-2θ method) using a powder X-ray diffraction device (X'Pert-PRO/MPD manufactured by PANalytical, Spectris Co., Ltd.). .

The X-ray diffraction pattern of the obtained ultrafine particles is shown in FIG. As a result of phase identification, the obtained ultrafine particles were identified as a hexagonal Cs _0.33 WO ₃ single phase. Further, crystal structure analysis was performed by Rietveld analysis using the X-ray diffraction pattern, and the crystallite diameter of the obtained ultrafine particles was 18.8 nm. Further, the peak top intensity value of the X-ray diffraction pattern of the obtained ultrafine particles was 4200 counts.

The composition of the obtained ultrafine particles was investigated by ICP emission spectrometry. As a result, the Cs concentration was 13.6% by mass, the W concentration was 65.3% by mass, and the Cs/W molar ratio was 0.29. It was confirmed that the remainder other than Cs and W was oxygen, and no other impurity elements contained at 1% by mass or more were present.

The BET specific surface area of the obtained ultrafine particles was measured using a BET specific surface area measuring device (HMmodel-1208, manufactured by Mountech Co., Ltd.), and was found to be 60.0 m ² /g. Note that nitrogen gas with a purity of 99.9% was used to measure the BET specific surface area.

Further, the content of volatile components in the composite tungsten oxide ultrafine particles according to Example 1 was measured and found to be 1.6% by mass.

10 parts by weight of the obtained ultrafine composite tungsten oxide particles, 80 parts by weight of toluene, and an acrylic polymer dispersant having an amine-containing functional group (acrylic resin with an amine value of 48 mg KOH/g and a decomposition temperature of 250°C). 10 parts by weight of the dispersant) (hereinafter referred to as "dispersant a") were mixed to prepare 3 kg of slurry. This slurry was put into a media stirring mill together with beads, and pulverized and dispersed for 0.5 hours. The medium stirring mill used was a horizontal cylindrical annular type (manufactured by Ashizawa Co., Ltd.), and the inner wall of the vessel and the rotor (rotating stirring part) were made of zirconia. Furthermore, beads made of YSZ (Yttria-Stabilized Zirconia) with a diameter of 0.1 mm were used. The rotation speed of the rotor was 14 rpm/sec, and the pulverization and dispersion treatment was performed at a slurry flow rate of 0.5 kg/min to obtain a composite tungsten oxide ultrafine particle dispersion according to Example 1.
The manufacturing conditions are shown in Table 1. Table 1 also describes the manufacturing conditions of Examples 2 to 13, which will be described later.

The value of the peak top intensity of the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles contained in the composite tungsten oxide ultrafine particle dispersion according to Example 1, that is, the composite tungsten oxide ultrafine particles after the pulverization and dispersion treatment, is 3000 counts. The peak position was 2θ=27.8°.
On the other hand, a silicon powder standard sample (640c manufactured by NIST) was prepared, and the peak intensity value of the silicon powder standard sample based on the (220) plane was measured and found to be 19,800 counts.
Therefore, when the value of the peak intensity of the standard sample is set to 1, it was found that the ratio of the XRD peak intensity of the ultrafine composite tungsten oxide particles after the pulverization and dispersion treatment according to Example 1 was 0.15. did.
Moreover, the crystallite diameter of the composite tungsten oxide ultrafine particles after the pulverization and dispersion treatment according to Example 1 was 16.9 nm.

Further, the dispersed particle size of the composite tungsten oxide ultrafine particle dispersion according to Example 1 was measured using a particle size measuring device based on a dynamic light scattering method, and was found to be 70 nm. In addition, as settings for particle size measurement, the particle refractive index was set to 1.81, and the particle shape was set to be non-spherical. Moreover, the background was measured using toluene, and the solvent refractive index was set to 1.50.

Toluene was removed from the composite tungsten oxide ultrafine particle dispersion according to Example 1 using a spray dryer to obtain a composite tungsten oxide ultrafine particle dispersion powder according to Example 1.
The results are shown in Table 3. Table 3 also lists the results of Examples 2 to 13, which will be described later.

The obtained composite tungsten oxide ultrafine particle dispersion powder is added to polyethylene terephthalate resin pellets, which is a thermoplastic resin, and mixed uniformly with a blender.The mixture is then melt-kneaded and extruded with a twin-screw extruder. The resulting strands were cut into pellets to obtain a masterbatch containing 80% by mass of composite tungsten oxide ultrafine particles as a near-infrared absorbing component.
The obtained masterbatch and a masterbatch of polyethylene terephthalate prepared in the same manner without adding ultrafine composite tungsten oxide particles were mixed at a weight ratio of 1:1, and the ultrafine composite tungsten oxide particles were mixed at 40% by mass. A mixed masterbatch according to Example 1 was obtained.
The mixed masterbatch according to Example 1 was melt-spun and then stretched to produce a polyester multifilament yarn according to Example 1. The average particle diameter of the composite tungsten oxide ultrafine particles at that point was calculated using an image processing device using a transmission electron microscope image, and was found to be 17 nm, which was approximately the same value as the crystallite diameter of 16.9 nm described above.
The obtained polyester multifilament yarn was cut to produce a polyester staple, and this was used to manufacture a spun yarn. Then, using this spun yarn, a knit product having heat retention properties according to Example 1 was obtained. (Here, the solar reflectance of the produced knit product sample was adjusted to 8%. In addition, the adjustment of the solar reflectance of the knit product sample to 8% is performed in the Examples and Comparative Examples described later. I went with everything.)

The spectral characteristics of the produced knit product were measured by the transmittance and reflectance of light with a wavelength of 200 to 2100 nm using a spectrophotometer manufactured by Hitachi, Ltd., and the solar absorption rate was calculated according to JIS A5759. The solar absorption rate was calculated from solar absorption rate (%) = 100% - solar transmittance (%) - solar reflectance (%). The calculated solar radiation absorption rate was 51.0%.
The results are shown in Table 5. Table 5 also lists the results obtained in Examples 2 to 28 and Comparative Examples 1 to 4, which will be described later.

Next, the effect of increasing the temperature on the back side of the fabric of the produced knit product was measured as follows.
In an environment of 20°C and 60% RH, a solar ray approximation spectrum lamp (Solar Simulator XL-03E50 Modified by SELIC Co., Ltd.) is irradiated from a distance of 30 cm from the fabric of the knit product at fixed intervals (0 seconds, The temperature of the back side of the fabric was measured at 30 seconds, 60 seconds, 180 seconds, 360 seconds, and 600 seconds using a radiation thermometer (HT-11 manufactured by Minolta Co., Ltd.).
The results are shown in Table 6. Table 6 also lists the results obtained in Examples 2 to 28 and Comparative Examples 1 to 4, which will be described later.

[Examples 2 to 6]
The composite tungsten oxide ultrafine particles and composite tungsten oxide according to Examples 2 to 6 were prepared by performing the same operations as in Example 1 except for changing the carrier gas flow rate, plasma gas flow rate, sheath gas flow rate, and raw material supply rate. An ultrafine particle dispersion was produced. The changed carrier gas flow rate conditions, raw material supply rate conditions, and other conditions are listed in Table 1. The same evaluation as in Example 1 was performed on the composite tungsten oxide ultrafine particles and the composite tungsten oxide ultrafine particle dispersion liquids according to Examples 2 to 6.
The manufacturing conditions and evaluation results are shown in Tables 1 and 3.

Further, in the same manner as in Example 1 except that the composite tungsten oxide ultrafine particle dispersion according to Examples 2 to 6 was used, the composite tungsten oxide ultrafine particle dispersion powder and the mixed master batch according to Examples 2 to 6 were used. Polyester multifilament yarns and knitted products were obtained and evaluated.
The evaluation results are shown in Tables 5 and 6.

[Example 7]
A composite represented by Cs _0.33 WO ₃ obtained by firing the mixed powder of Cs ₂ CO ₃ and H ₂ WO ₄ described in Example 1 at 800° C. in a mixed gas atmosphere of nitrogen gas and hydrogen gas. It was changed to tungsten oxide and used as a raw material to be fed into a high frequency plasma reactor. Other than that, the composite tungsten oxide ultrafine particles and composite tungsten oxide ultrafine particle dispersion according to Example 7 were produced in the same manner as in Example 1. The obtained ultrafine particles and their dispersion were evaluated in the same manner as in Example 1.
The manufacturing conditions and evaluation results are shown in Tables 1 and 3.

Further, in the same manner as in Example 1 except that the composite tungsten oxide ultrafine particle dispersion according to Example 7 was used, the composite tungsten oxide ultrafine particle dispersion powder according to Example 7, the mixed masterbatch, and the polyester multifilament yarn were prepared. and knitted products.
The evaluation results are shown in Tables 5 and 6.

[Example 8]
Composite tungsten oxide ultrafine particles and a composite tungsten oxide ultrafine particle dispersion according to Example 8 were produced by performing the same operations as in Example 7, except that the carrier gas flow rate and raw material supply rate were changed. The obtained ultrafine particles and their dispersion were evaluated in the same manner as in Example 1.
The manufacturing conditions and evaluation results are shown in Tables 1 and 3.

Further, in the same manner as in Example 1 except that the composite tungsten oxide ultrafine particle dispersion according to Example 8 was used, the composite tungsten oxide ultrafine particle dispersion powder according to Example 8, the masterbatch, and the polyester multifilament yarn were prepared. The knitted products were obtained and evaluated.
The evaluation results are shown in Tables 5 and 6.

[Examples 9 to 13]
Dissolve 0.148 kg of Rb ₂ CO ₃ in 0.330 kg of water, add this to 1.000 kg of H ₂ WO ₄ , stir thoroughly, and then dry to obtain the desired composition of Rb _0.32 WO ₃ . A mixed powder according to Example 9 was obtained.
Dissolve 0.375 kg of K ₂ CO ₃ in 0.330 kg of water, add this to 1.000 kg of H ₂ WO ₄ , stir thoroughly, and then dry to obtain the desired composition of K _0.27 WO _3. A mixed powder according to Example 10 was obtained.
Dissolve 0.320 kg of TlNO ₃ in 0.330 kg of water, add this to 1.000 kg of H ₂ WO ₄ , stir thoroughly, and then dry to obtain Example 11 of Tl _0.19 WO ₃ with the target composition. A mixed powder was obtained.
Dissolve 0.111 kg of BaCO ₃ in 0.330 kg of water, add this to 1.000 kg of H ₂ WO ₄ , stir thoroughly, and then dry to obtain Example 12 of Ba _0.14 WO ₃ with the target composition. A mixed powder was obtained.
Dissolve 0.0663 kg of K ₂ CO ₃ and 0.0978 kg of Cs ₂ CO ₃ in 0.330 kg of water, add this to 1.000 kg of H ₂ WO ₄ , stir thoroughly, and then dry to obtain the desired composition. A mixed powder of K _0.24 Cs _0.15 WO ₃ according to Example 13 was obtained.

The composite tungsten oxide ultrafine particles according to Examples 9 to 13 were prepared in the same manner as in Example 1, except that the mixed powders according to Examples 9 to 13 were used as raw materials to be introduced into the high-frequency thermal plasma reactor. A composite tungsten oxide ultrafine particle dispersion was produced. The obtained ultrafine particles and their dispersion were evaluated in the same manner as in Example 1.
The manufacturing conditions and evaluation results are shown in Tables 1 and 3.

Further, in the same manner as in Example 1 except that the composite tungsten oxide ultrafine particle dispersion according to Examples 9 to 13 was used, the composite tungsten oxide ultrafine particle dispersion powder according to Examples 9 to 13 and the mixed masterbatch were mixed. Polyester multifilament yarns and knitted products were obtained and evaluated.
The evaluation results are shown in Tables 5 and 6.

[Example 14]
10.8 g of Cs ₂ CO ₃ was dissolved in 16.5 g of water, and the solution was added to 50 g of H ₂ WO ₄ , thoroughly stirred, and then dried. The dried material was heated while supplying 2% H ₂ gas using N ₂ gas as a carrier, and baked at a temperature of 800° C. for 30 minutes. Thereafter, a composite tungsten oxide according to Example 14 was obtained by a solid phase method of firing at 800° C. for 90 minutes in an N ₂ gas atmosphere.
The manufacturing conditions are shown in Table 2. Table 2 also describes the manufacturing conditions of Examples 15 to 28 and Comparative Examples 1 to 4, which will be described later.

Except for this, a composite tungsten oxide ultrafine particle dispersion according to Example 14 was produced in the same manner as in Example 1. However, the time for the pulverization and dispersion treatment using the media stirring mill was 2 hours. The obtained ultrafine particles and their dispersion were evaluated in the same manner as in Example 1.
As a result of measuring the X-ray diffraction pattern of the obtained ultrafine particles and identifying the phase, the obtained ultrafine particles were identified as a hexagonal Cs _0.33 WO ₃ single phase.
The results are shown in Table 4. Table 4 also describes the manufacturing conditions of Examples 15 to 28 and Comparative Examples 1 to 4, which will be described later.

Further, in the same manner as in Example 1 except that the composite tungsten oxide ultrafine particle dispersion according to Example 14 was used, the composite tungsten oxide ultrafine particle dispersion powder according to Example 14, the mixed masterbatch, and the polyester multifilament yarn were prepared. and knitted products.
The evaluation results are shown in Tables 5 and 6.

[Example 15]
0.216 kg of Cs ₂ CO ₃ was dissolved in 0.330 kg of water, and the resulting solution was added to 1.000 kg of H ₂ WO ₄ and sufficiently stirred, followed by drying to obtain a dried product. The dried material was heated while supplying 5% H ₂ gas using N ₂ gas as a carrier, and baked at a temperature of 800° C. for 1 hour. Thereafter, a solid phase reaction method of firing at 800° C. for 2 hours in an N ₂ gas atmosphere was further carried out to obtain a composite tungsten oxide according to Example 15.

10 parts by weight of the obtained composite tungsten oxide according to Example 15 and 90 parts by weight of water were mixed to prepare about 3 kg of slurry. Note that no dispersant was added to this slurry. This slurry was put into a media stirring mill together with the beads, and pulverized and dispersed for 2 hours. The medium stirring mill used was a horizontal cylindrical annular type (manufactured by Ashizawa Co., Ltd.), and the inner wall of the vessel and the rotor (rotating stirring part) were made of zirconia. Furthermore, beads made of YSZ (Yttria-Stabilized Zirconia) with a diameter of 0.1 mm were used. The rotational speed of the rotor was 14 rpm/sec, and the pulverization and dispersion treatment was performed at a slurry flow rate of 0.5 kg/min to obtain a composite tungsten oxide ultrafine particle aqueous dispersion according to Example 15.
The dispersed particle diameter of the aqueous dispersion of composite tungsten oxide ultrafine particles according to Example 15 was measured and found to be 70 nm. Note that the settings for measuring the dispersed particle size were such that the particle refractive index was 1.81 and the particle shape was non-spherical. Further, the background was measured using water, and the solvent refractive index was set to 1.33.

Next, about 3 kg of the obtained ultrafine composite tungsten oxide particle dispersion was dried in an atmospheric dryer to obtain ultrafine composite tungsten oxide particles according to Example 15. As the atmospheric dryer, a constant temperature oven (Model SPH-201 manufactured by ESPEC Co., Ltd.) was used, the drying temperature was 70° C., and the drying time was 96 hours.
The manufacturing conditions are shown in Table 2.

As a result of measuring the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles according to Example 15 and identifying the phase, the obtained ultrafine particles were identified as a hexagonal Cs _0.33 WO ₃ single phase. Further, the peak top intensity value of the X-ray diffraction pattern of the obtained ultrafine particles was 4200 counts, the peak position was 2θ=27.8°, and the crystallite diameter was 23.7 nm. On the other hand, a silicon powder standard sample (manufactured by NIST, 640c) was prepared, and the peak intensity value based on the (220) plane in the silicon powder standard sample was measured and found to be 19,800 counts. Therefore, when the value of the peak intensity of the standard sample is set to 1, it was found that the ratio of the XRD peak intensity of the composite tungsten oxide ultrafine particles after the pulverization and dispersion treatment according to Example 15 was 0.21. did.

The composition of the obtained composite tungsten oxide ultrafine particles according to Example 15 was investigated by ICP emission spectrometry. As a result, the Cs concentration was 15.2% by mass, the W concentration was 64.6% by mass, and the Cs/W molar ratio was 0.33. The remainder other than Cs and W was oxygen. It was also confirmed that there were no other impurity elements contained in an amount of 1% by mass or more.

The BET specific surface area of the pulverized composite tungsten oxide ultrafine particles according to Example 15 was measured and was found to be 42.6 m ² /g.

Further, the volatile component content of the composite tungsten oxide ultrafine particles according to Example 15 was measured and found to be 2.2% by mass.

10 parts by weight of the obtained composite tungsten oxide ultrafine particles were dispersed in 80 parts by weight of toluene as a solvent and 10 parts by weight of dispersant A to prepare 50 g of a dispersion liquid, and the dispersed particle diameter of the dispersion liquid was measured and found to be 80 nm. Met. In addition, as settings for measuring the dispersed particle size, the particle refractive index was set to 1.81, and the particle shape was set to be non-spherical. Further, it was diluted with toluene and measured, and the solvent refractive index was set to 1.50.
The results are shown in Table 4.

Toluene was removed from the composite tungsten oxide ultrafine particle dispersion according to Example 15 using a spray dryer to obtain a composite tungsten oxide ultrafine particle dispersion powder according to Example 15.
The obtained composite tungsten oxide ultrafine particle dispersion powder is added to polyethylene terephthalate resin pellets, which is a thermoplastic resin, and mixed uniformly with a blender.The mixture is then melt-kneaded and extruded with a twin-screw extruder. The resulting strands were cut into pellets to obtain a masterbatch containing 80% by mass of composite tungsten oxide ultrafine particles as a near-infrared absorbing component.
The obtained masterbatch and a masterbatch of polyethylene terephthalate prepared in the same manner without adding ultrafine composite tungsten oxide particles were mixed at a weight ratio of 1:1, and the ultrafine composite tungsten oxide particles were mixed at 40% by mass. A mixed masterbatch according to Example 15 was obtained.
The mixed masterbatch according to Example 15 was melt-spun and then stretched to produce a polyester multifilament yarn according to Example 15. The average particle diameter of the composite tungsten oxide ultrafine particles at that point was calculated using an image processing device using a transmission electron microscope image, and was found to be 23 nm, which was approximately the same value as the crystallite diameter of 23.7 nm described above.
The obtained polyester multifilament yarn was cut to produce a polyester staple, and this was used to manufacture a spun yarn. Using this spun yarn, a knit product having heat retention properties according to Example 15 was obtained.

The spectral characteristics of the produced knit product were measured by the transmittance and reflectance of light with a wavelength of 200 to 2100 nm using a spectrophotometer manufactured by Hitachi, Ltd., and the solar absorption rate was calculated according to JIS A5759. The solar absorption rate was calculated from solar absorption rate (%) = 100% - solar transmittance (%) - solar reflectance (%). The calculated solar radiation absorption rate was 52.3%.
The results are shown in Table 5.

Next, the effect of increasing the temperature on the back side of the fabric of the produced knit product was measured as follows.
In an environment of 20°C and 60% RH, a solar ray approximation spectrum lamp (Solar Simulator XL-03E50 Modified by SELIC Co., Ltd.) is irradiated from a distance of 30 cm from the fabric of the knit product at fixed intervals (0 seconds, The temperature of the back side of the fabric was measured at 30 seconds, 60 seconds, 180 seconds, 360 seconds, and 600 seconds using a radiation thermometer (HT-11 manufactured by Minolta Co., Ltd.).
The results are shown in Table 6.

[Example 16]
Composite tungsten oxide ultrafine particles and composite tungsten oxide ultrafine particle dispersion according to Example 16 were prepared in the same manner as in Example 15, except that the drying process using an atmospheric dryer was changed to a vacuum drying process using a vacuum stirring and crushing machine. A masterbatch mixed with a composite tungsten oxide ultrafine particle dispersion powder, a polyester multifilament yarn, and a knitted product were manufactured and evaluated.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.
The vacuum stirring and crushing machine used was an Ishikawa type stirring and crushing machine 24P type (manufactured by Tajima Kagaku Kikai Co., Ltd.), and the drying temperature in the vacuum drying process was 80°C, the drying time was 32 hours, and the rotation frequency of the kneading mixer was The frequency was 40 Hz, and the pressure inside the vacuum container was 0.001 MPa or less.

[Example 17]
A composite of the composite tungsten oxide ultrafine particles according to Example 17 and the composite tungsten oxide ultrafine particle dispersion was prepared in the same manner as in Example 15 except that the drying process using an atmospheric dryer was changed to a spray drying process using a spray dryer. A tungsten oxide ultrafine particle dispersion powder, a mixed masterbatch, a polyester multifilament yarn, and a knit product were produced and evaluated.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.
The spray dryer used was a spray dryer model ODL-20 (manufactured by Okawara Kakoki Co., Ltd.).

[Examples 18-20]
The composite tungsten oxide ultrafine particles and composite tungsten oxide ultrafine particle dispersions according to Examples 18 to 20 were prepared in the same manner as in Examples 15 to 17, except that the pulverization and dispersion treatment time using the media stirring mill was changed to 1 hour. A composite tungsten oxide ultrafine particle dispersion powder, a mixed masterbatch, a polyester multifilament yarn, and a knit product were produced and evaluated.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Examples 21 to 23]
In preparing the composite tungsten oxide ultrafine particle dispersion, the same procedure as in Examples 15 to 17 described above was carried out, except that 10 parts by weight of the composite tungsten oxide and 90 parts by weight of propylene glycol monoethyl ether were mixed as a solvent. By the synthetic manufacturing method, the composite tungsten oxide ultrafine particles, composite tungsten oxide ultrafine particle dispersion, composite tungsten oxide ultrafine particle dispersion powder, mixed masterbatch, polyester multifilament yarn, and knit product according to Examples 21 to 23 were produced. manufactured and evaluated.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Example 24]
Composite tungsten oxide ultrafine particles were obtained in the same manner as in Example 1. Thereafter, 10 parts by weight of the obtained ultrafine particles, 80 parts by weight of toluene, and 10 parts by weight of dispersant a were mixed to prepare 50 g of slurry. This slurry was subjected to dispersion treatment for 0.5 hours using an ultrasonic homogenizer (US-600TCVP manufactured by Nippon Seiki Seisakusho Co., Ltd.) to obtain a composite tungsten oxide ultrafine particle dispersion according to Example 24, and the same as in Example 1. A composite tungsten oxide ultrafine particle dispersion powder, a mixed masterbatch, a polyester multifilament yarn, and a knitted product were produced and evaluated using the method described above.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Example 25]
A nylon 6 masterbatch containing 30% by mass of composite tungsten oxide ultrafine particles was prepared in the same manner as in Example 1, except that nylon 6 resin pellets were used as the thermoplastic resin, and a composite prepared in the same manner was This was mixed with a nylon 6 masterbatch to which no ultrafine tungsten oxide particles were added at a weight ratio of 1:1 to obtain a mixed masterbatch according to Example 25 containing 15% by mass of ultrafine composite tungsten oxide particles.
The mixed masterbatch according to Example 25 was melt-spun and then stretched to produce a nylon multifilament yarn. The obtained multifilament yarn was cut to produce a nylon staple, which was used to manufacture a spun yarn. A nylon fiber product with heat retention properties was manufactured using this spun yarn. The produced mixed masterbatch, nylon multifilament yarn, and nylon fiber product were evaluated in the same manner as in Example 1.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Example 26]
A polyacrylonitrile masterbatch containing 50% by mass of composite tungsten oxide ultrafine particles was prepared in the same manner as in Example 1, except that acrylic resin pellets were used as the thermoplastic resin, and composite tungsten prepared in the same manner was prepared. A mixed masterbatch according to Example 26 containing 25% by mass of composite tungsten oxide ultrafine particles was obtained by mixing with a polyacrylonitrile masterbatch to which no ultrafine oxide particles were added at a weight ratio of 1:1.
The mixed masterbatch according to Example 26 was spun and then stretched to produce an acrylic multifilament yarn. The obtained multifilament yarn was cut to produce an acrylic staple, and a spun yarn was produced using this. An acrylic fiber product with heat retention properties was manufactured using this spun yarn. The produced mixed masterbatch, acrylic multifilament yarn, and acrylic fiber product were evaluated in the same manner as in Example 1.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Example 27]
Polytetramethylene ether glycol (PTG2000) containing 30% by mass of composite tungsten oxide ultrafine particles according to Example 1 was reacted with 4,4-diphenylmethane diisocyanate to prepare an isocyanate group-terminated prepolymer. Next, the prepolymer was polymerized by reacting 1,4-butanediol and 3-methyl-1,5-pentanediol as chain extenders to produce a thermoplastic polyurethane solution.
The obtained thermoplastic polyurethane solution was used as a spinning dope and was spun, and the spun yarn was subsequently drawn to obtain polyurethane elastic fibers. A urethane fiber product having heat retention properties was manufactured using this polyurethane elastic fiber. The produced polyurethane elastic fibers and urethane fiber products were evaluated in the same manner as in Example 1.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Example 28]
Composite tungsten oxide ultrafine particles were obtained in the same manner as in Example 1. Thereafter, 10 parts by weight of the obtained ultrafine particles, 5 parts by weight of ZrO ₂ fine particles having an average particle size of 30 nm, 70 parts by weight of toluene, and 15 parts by weight of dispersant a were mixed to prepare 3 kg of slurry. This slurry was subjected to the same pulverization and dispersion treatment as in Example 1 to obtain a composite tungsten oxide ultrafine particle dispersion according to Example 28, and further in the same manner as in Example 1 to obtain a composite tungsten oxide ultrafine particle dispersion powder. A mixed masterbatch, polyester multifilament yarn, and knitted products were produced and evaluated.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Comparative Examples 1 and 2]
Composite tungsten oxide ultrafine particles and composite tungsten oxide ultrafine particles according to Comparative Examples 1 and 2 were prepared in the same manner as in Example 1, except that the carrier gas flow rate, plasma gas flow rate, sheath gas flow rate, and raw material supply rate were changed. A dispersion liquid, a composite tungsten oxide ultrafine particle dispersion powder, a mixed masterbatch, a polyester multifilament yarn, and a knit product were manufactured and evaluated.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Comparative example 3]
The composite tungsten oxide ultrafine particles according to Comparative Example 3 and the composite tungsten oxide ultrafine particles according to Comparative Example 3 were prepared in the same manner as in Example 1, except that the high frequency power was 15 kW in order to generate a thermal plasma having a high temperature part of 5000 to 10000 K. A tungsten oxide ultrafine particle dispersion, a composite tungsten oxide ultrafine particle dispersion powder, a mixed masterbatch, a polyester multifilament yarn, and a knit product were produced and evaluated.
The manufacturing conditions and evaluation results are shown in Tables 2, 4, 5, and 6.

[Comparative example 4]
Comparative results were obtained by performing the same operation as in Example 15, except that the aqueous dispersion of composite tungsten oxide ultrafine particles according to Example 15 was obtained by 20 hours of pulverization and dispersion treatment instead of 2 hours of pulverization and dispersion treatment. A composite tungsten oxide ultrafine particle aqueous dispersion according to Example 4 was obtained. The dispersed particle diameter of the composite tungsten oxide ultrafine particle aqueous dispersion according to Comparative Example 4 was measured and found to be 120 nm. Note that the settings for measuring the dispersed particle size were such that the particle refractive index was 1.81 and the particle shape was non-spherical. Further, the background was measured using water, and the solvent refractive index was set to 1.33.
The results are shown in Table 2.

As a result of measuring the X-ray diffraction pattern of the composite tungsten oxide ultrafine particles according to Comparative Example 4 and identifying the phase, the obtained ultrafine particles were identified as having a hexagonal Cs _0.33 WO ₃ single phase. Further, the peak top intensity value of the X-ray diffraction pattern of the obtained ultrafine particles was 1300 counts, the peak position was 2θ=27.8°, and the crystallite diameter was 8.1 nm. On the other hand, a silicon powder standard sample (manufactured by NIST, 640c) was prepared, and the peak intensity value based on the (220) plane in the silicon powder standard sample was measured and found to be 19,800 counts. Therefore, when the peak intensity value of the standard sample is set to 1, the ratio of the XRD peak intensity of the composite tungsten oxide ultrafine particles after the pulverization and dispersion treatment according to Example 1 was found to be 0.07. did.

When the BET specific surface area of the composite tungsten oxide ultrafine particles according to Comparative Example 4 obtained by pulverization was measured, it was 102.8 m ² /g.
Further, the volatile component content of the composite tungsten oxide ultrafine particles according to Comparative Example 4 was measured and found to be 2.2% by mass.

10 parts by weight of the obtained composite tungsten oxide ultrafine particles were dispersed in 80 parts by weight of toluene and 10 parts by weight of dispersant a to obtain 50 g of a composite tungsten oxide ultrafine particle dispersion according to Comparative Example 4. The dispersed particle diameter of the composite tungsten oxide ultrafine particle dispersion was measured and found to be 120 nm. Note that the settings for measuring the dispersed particle size were such that the particle refractive index was 1.81 and the particle shape was non-spherical. Note that the background was measured using toluene, and the solvent refractive index was set to 1.50.
The results are shown in Table 4.

Toluene was removed from the composite tungsten oxide ultrafine particle dispersion according to Comparative Example 4 using a spray dryer to obtain a composite tungsten oxide ultrafine particle dispersion powder according to Comparative Example 4.
The obtained composite tungsten oxide ultrafine particle dispersion powder is added to polyethylene terephthalate resin pellets, which is a thermoplastic resin, and mixed uniformly with a blender.The mixture is then melt-kneaded and extruded with a twin-screw extruder. The resulting strands were cut into pellets to obtain a masterbatch containing 80% by mass of composite tungsten oxide ultrafine particles as a near-infrared absorbing component.
The obtained masterbatch and a masterbatch of polyethylene terephthalate prepared in the same manner without adding ultrafine composite tungsten oxide particles were mixed at a weight ratio of 1:1, and the ultrafine composite tungsten oxide particles were mixed at 40% by mass. A mixed masterbatch according to Comparative Example 4 was obtained.
The mixed masterbatch according to Comparative Example 4 was melt-spun and then stretched to produce a polyester multifilament yarn according to Comparative Example 4. The average particle diameter of the composite tungsten oxide ultrafine particles at that point was calculated using an image processing device using a transmission electron microscope image, and was found to be 120 nm, which is significantly larger than the crystallite diameter of 8.1 nm mentioned above. Indicated.
The obtained polyester multifilament yarn was cut to produce a polyester staple, and this was used to manufacture a spun yarn. Using this spun yarn, a knit product having heat retention properties according to Comparative Example 4 was obtained.

The spectral characteristics of the produced knit product were measured by the transmittance and reflectance of light with a wavelength of 200 to 2100 nm using a spectrophotometer manufactured by Hitachi, Ltd., and the solar absorption rate was calculated according to JIS A5759. The solar absorption rate was calculated from solar absorption rate (%) = 100% - solar transmittance (%) - solar reflectance (%). The calculated solar radiation absorption rate was 43.3%.
The results are shown in Table 5.

Next, the effect of increasing the temperature on the back side of the fabric of the produced knit product was measured as follows.
In an environment of 20°C and 60% RH, a solar ray approximation spectrum lamp (Solar Simulator XL-03E50 Modified by SELIC Co., Ltd.) is irradiated from a distance of 30 cm from the fabric of the knit product at fixed intervals (0 seconds, The temperature of the back side of the fabric was measured at 30 seconds, 60 seconds, 180 seconds, 360 seconds, and 600 seconds using a radiation thermometer (HT-11 manufactured by Minolta Co., Ltd.).
The results are shown in Table 6.

[summary]
As is clear from Tables 3 and 4, the composite tungsten oxide ultrafine particles contained in the filament yarns according to Examples 1 to 28 have the XRD peak intensity value of the silicon powder standard sample (manufactured by NIST, 640c) (220) plane. The ratio of the XRD peak top intensity of the previous composite tungsten oxide ultrafine particles to the composite tungsten oxide ultrafine particles was 0.13 or more, and the composite tungsten oxide ultrafine particles had a crystallite diameter of 1 nm or more. Here, in the examples, since the average particle diameter and crystallite diameter of the composite tungsten oxide ultrafine particles in the filament yarn are almost the same, the composite tungsten oxide ultrafine particles used have a volume ratio of the amorphous phase. It is considered that they are single-crystal composite tungsten oxide ultrafine particles with a particle size of 50% or less.
On the other hand, in Comparative Examples 1, 2, and 4, the average particle diameter of the composite tungsten oxide ultrafine particles in the filament yarn was larger than the crystallite diameter, and it is considered that they were not single crystals. Further, in Comparative Example 3, different phases (WO ₂ and W) were generated.
The filament yarn manufactured using the composite tungsten oxide ultrafine particles according to this example exhibited excellent near-infrared absorption characteristics as shown in Table 5. Furthermore, when compared with the comparative example, the fabric back surface temperature of each textile product according to the example was higher by 6° C. or more on average, as shown in Table 6, and it was found that the fabric was excellent in heat retention.

1 Thermal plasma 2 High frequency coil 3 Sheath gas supply nozzle 4 Plasma gas supply nozzle 5 Raw material powder supply nozzle 6 Reaction vessel 7 Suction tube 8 Filter

Claims (15)

A near-infrared absorbing fiber containing ultrafine particles having near-infrared absorbing properties inside the fiber,
The ultrafine particles having near-infrared absorption characteristics have the general formula MxWyOz (where M is one or more elements selected from alkali metals, alkaline earth metals, and Tl, W is tungsten, O is oxygen, .001≦x/y≦1, 2.0<z/y≦3.0),
The crystallite diameter is 10 nm or more and 200 nm or less,
When the value of the XRD peak intensity of the (220) plane of the silicon powder standard sample (manufactured by NIST, 640c) is taken as 1, the value of the ratio of the XRD peak top intensity is 0.13 or more. Composite tungsten oxide ultrafine particles. A near-infrared absorbing fiber characterized by: The near-infrared absorbing fiber according to claim 1, wherein the composite tungsten oxide ultrafine particles have a hexagonal crystal structure. The near-infrared absorbing fiber according to claim 1 or 2, wherein the volatile component content of the composite tungsten oxide ultrafine particles is 2.5% by mass or less. The method according to any one of claims 1 to 3, wherein the content of the composite tungsten oxide ultrafine particles is 0.001% by mass or more and 80% by mass or less based on the solid content of the fiber. Infrared absorbing fiber. A fiber further containing fine particles of a far-infrared emitting substance on the surface and/or inside of the near-infrared absorbing fiber according to any one of claims 1 to 4,
A near-infrared absorbing fiber characterized in that the content of the fine particles of the far-infrared emitting substance is 0.001% by mass or more and 80% by mass or less based on the solid content of the fiber. The fibers are selected from one or more of synthetic fibers, semi-synthetic fibers, natural fibers, regenerated fibers, inorganic fibers, or mixed yarns formed by blending, doubling, or blending these fibers. The near-infrared absorbing fiber according to any one of claims 1 to 5. The synthetic fibers are selected from polyurethane fibers, polyamide fibers, acrylic fibers, polyester fibers, polyolefin fibers, polyvinyl alcohol fibers, polyvinylidene chloride fibers, polyvinyl chloride fibers, and polyether ester fibers. The near-infrared absorbing fiber according to claim 6, wherein the near-infrared absorbing fiber is one or more types of synthetic fiber. The near-infrared absorbing material according to claim 6 or 7, wherein the semi-synthetic fiber is one or more semi-synthetic fibers selected from cellulose fiber, protein fiber, chlorinated rubber, and hydrochloric acid rubber. fiber. The near-infrared absorbing fiber according to any one of claims 6 to 8, wherein the natural fiber is any one or more natural fibers selected from vegetable fibers, animal fibers, and mineral fibers. 10. The regenerated fiber according to claim 6, wherein the regenerated fiber is any one or more regenerated fiber selected from cellulose fiber, protein fiber, algin fiber, rubber fiber, chitin fiber, and mannan fiber. Near-infrared absorbing fiber according to any one of the above. The near-infrared absorbing fiber according to any one of claims 6 to 10, wherein the inorganic fiber is any one or more inorganic fibers selected from metal fibers, carbon fibers, and silicate fibers. Any one of claims 1 to 11, wherein the surface of the composite tungsten oxide ultrafine particles is coated with a compound containing any one or more elements selected from silicon, zirconium, titanium, and aluminum. A near-infrared absorbing fiber described in Crab. The near-infrared absorbing fiber according to claim 12, wherein the compound is an oxide. A textile product obtained by processing the near-infrared absorbing fiber according to any one of claims 1 to 13. A method for producing a near-infrared absorbing fiber containing ultrafine particles having near-infrared absorbing properties, the method comprising:
The ultrafine particles having near-infrared absorption characteristics have the general formula MxWyOz (where M is one or more elements selected from alkali metals, alkaline earth metals, and Tl; W is tungsten; O is oxygen; .001≦x/y≦1, 2.0<z/y≦3.0),
The crystallite diameter is 10 nm or more and 200 nm or less,
The composite tungsten oxide particles have an XRD peak top intensity ratio value of 0.13 or more, where the value of the XRD peak intensity of the (220) plane of a silicon powder standard sample (manufactured by NIST, 640c) is set to 1. Obtained by synthesizing so that
A method for producing a near-infrared absorbing fiber, comprising incorporating the obtained composite tungsten oxide particles into the fiber while maintaining the ratio of the XRD peak top intensities to 0.13 or more.