JP2019002004A - Photothermal conversion material, photothermal conversion composition and photothermal conversion molded body - Google Patents

Abstract

To provide a photothermal conversion material including a composite containing metal microparticles and fine cellulose exerting notable photothermal conversion characteristics, and also to provide a photothermal conversion composition, a photothermal conversion molded body and a usage.SOLUTION: A photothermal conversion material is a composite 1 in which metal microparticles and at least one fine cellulose 12 are composite. A photothermal conversion composition includes the photothermal conversion material. The photothermal conversion molded body is manufactured using the photothermal conversion composition, and includes a resin at least containing one of a water-soluble polymer, an aqueous dispersion, an aqueous emulsion and a photocurable resin.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light-to-heat conversion material, a light-to-heat conversion composition, and a light-to-heat conversion molded article including a composite containing metal fine particles and refined cellulose.

  In recent years, functional materials using natural polymers, which are environmentally friendly materials that can be used continuously, have been actively developed, and replacement from petroleum-derived materials to biomass materials is expected. For example, plant materials such as cellulose are known as environmentally friendly natural polymer materials having biodegradability. Cellulose, the main component of plants and wood, is a natural polymer material that is accumulated in large quantities on the earth. In the wood, dozens or more cellulose molecules are bundled in wood to form fine fibers (microfibrils) having a high crystallinity and a fiber diameter on the order of nanometers. Furthermore, a large number of fine fibers are hydrogen-bonded to each other to form cellulose fibers, which are plant supports.

There is known a method of using this cellulose fiber by making it finer (nanofiber) until the fiber diameter becomes nanometer order. For example, a method is known in which an N-oxyl compound is used as an oxidation catalyst to oxidize part of a hydroxyl group of cellulose to at least one functional group selected from the group consisting of a carboxy group and an aldehyde group. According to this method, refined cellulose (hereinafter sometimes referred to as “CSNF”) having a cellulose I-type crystal structure having a maximum fiber diameter of 1000 nm or less and a number average fiber diameter of 2 nm to 150 nm is obtained. (For example, refer to Patent Document 1).
The refined cellulose has been studied for use in gas barrier packaging materials (see Patent Document 2) and for improving the strength of the resin by compounding with the resin (see Patent Document 3).

  In Patent Document 4, when metal ions are reduced and precipitated in the presence of micronized cellulose, the growth of metal microparticles is controlled by micronized cellulose, and a metal / micronized cellulose composite in which metal microparticles and micronized cellulose are combined. Is disclosed. This metal / micronized cellulose composite has the characteristics of nano-sized particles (hereinafter referred to as “fine particles”).

In the metal fine particles, a phenomenon in which an electric field and an external electric field (light, etc.) resonate occurs due to vibration of free electrons (localized surface plasmon resonance (LSPR)). This LSPR causes light absorption in a specific wavelength region according to the metal species, shape and particle diameter of the metal fine particles, and the surrounding dielectric constant.
In particular, the resonance wavelength of anisotropic metal fine particles varies greatly depending on, for example, the particle diameter / thickness aspect ratio in the case of a flat plate.
Therefore, even in the metal / micronized cellulose composite, it is possible to absorb light in a specific wavelength region such as the visible light region to the near infrared region by controlling the aspect ratio.

JP 2008-1728 A JP 2012-149114 A Japanese Patent No. 6020334 International Publication No. 2015/170613 International Publication No. 2016/039129

  As a result of studies on the metal / micronized cellulose composite by the present inventors, it has been found that the metal / micronized cellulose composite absorbs light and exhibits photothermal conversion characteristics that generate heat. The metal / micronized cellulose composite has remarkable photothermal conversion characteristics and exhibits its effect in a small amount. Regarding the photothermal conversion characteristics of the metal / micronized cellulose composite, the characteristics and configurations and applications that utilize the characteristics have not been known.

  The present invention has been made in view of the above-described circumstances, and provides a photothermal conversion material, a photothermal conversion composition, and a photothermal conversion, including a composite containing metal fine particles and fine cellulose, which exhibit remarkable photothermal conversion characteristics. It aims at providing a molded object and an application.

  The photothermal conversion material according to one embodiment of the present invention is a composite in which metal fine particles and at least one or more refined celluloses are combined.

  The photothermal conversion composition concerning one mode of the present invention contains the above-mentioned photothermal conversion material.

  The photothermal conversion molded body according to an aspect of the present invention is produced using the above photothermal conversion composition, and includes a resin having at least one of a water-soluble polymer, an aqueous dispersion, an aqueous emulsion, and a photocurable resin.

  According to the present invention, there are provided a photothermal conversion material, a photothermal conversion composition, a photothermal conversion molded body, and a use including a composite containing metal fine particles and finely divided cellulose that exhibit remarkable photothermal conversion characteristics. Can do.

It is a figure which shows typically the photothermal conversion material which concerns on one Embodiment of this invention. It is a figure (transmission electron microscope image) which shows the result of having observed the photothermal conversion material which concerns on one Embodiment of this invention by uranyl dyeing | staining and expanding by the transmission electron microscope (TEM). It is a figure which shows the result of having observed the photothermal conversion material which concerns on one Embodiment of this invention with the scanning electron microscope (SEM). It is a figure which shows the result of having expanded and observed the photothermal conversion material which concerns on one Embodiment of this invention with a scanning transmission electron microscope (STEM). It is a figure which shows the result of having expanded and observed the photothermal conversion material which concerns on one Embodiment of this invention with the scanning electron microscope (SEM). It is a figure (transmission electron microscope image) which shows the result of having observed the photothermal conversion material which concerns on one Embodiment of this invention from the cross-sectional direction with the transmission electron microscope (TEM). It is a figure which shows typically the photothermal conversion molded object which concerns on one Embodiment of this invention. It is a figure which shows the result of having expanded and observed an example (complex A) of the photothermal conversion material which concerns on one Embodiment of this invention with a scanning transmission electron microscope (STEM). It is a figure which shows the result of having expanded and observed an example (composite B) of the photothermal conversion material which concerns on one Embodiment of this invention with a scanning transmission electron microscope (STEM). It is a figure (transmission electron microscope image) which shows the result of having measured the temperature rise of the film which provided the photothermal conversion material (complex A and composite B) which concerns on one Embodiment of this invention on the base material. It is a figure which shows the result of having measured the transmittance | permeability of the micronized cellulose aqueous dispersion of Example 1. FIG. It is a figure which shows the evaluation result of the viscosity characteristic of the micronized cellulose aqueous dispersion of Example 1. It is a scanning transmission electron microscope (STEM) image of an example (composite C) of the photothermal conversion material which concerns on one Embodiment of this invention.

  Embodiments to which the present invention is applied will be described below in detail with reference to the drawings. Note that the drawings used in the following description are for explaining the configuration of the embodiment of the present invention, and the size, thickness, dimensions, and the like of each part shown in the drawings may differ from the actual dimensional relationship.

FIG. 1 is a diagram schematically showing a complex 1 according to the present embodiment.
As shown in FIG. 1, the photothermal conversion material includes a composite 1 containing metal fine particles 11 and refined cellulose 12.

  While examining the functionalization of the micronized cellulose 12, the composite 1 of the metal microparticle 11 and the micronized cellulose 12, which is a novel material in which the metal microparticles 11 and the micronized cellulose 12 are combined, was developed. The complex 1 can shield light in a specific wavelength region from the visible light region to the infrared region by LSPR (Localized Surface Plasmon Resonance (LSPR)), which is a feature of the metal fine particles 11.

  As a result of investigations by the inventors, it was found that the composite 1 exhibits light-to-heat conversion characteristics that absorb light and generate heat, and that the composite 1 can be provided as a photothermal conversion material. It has been found that a conversion composition and a photothermal conversion molding can be provided.

  Hereinafter, after describing in detail the composite body 1, the manufacturing method of the composite body 1, the photothermal conversion molded body 2, and the photothermal conversion composition, the uses of the composite body 1 and the like will be described.

[Composite 1]
The composite 1 is a composite (metal / fine cellulose composite) having metal fine particles 11 and fine cellulose 12.
As shown in FIG. 1, the composite 1 is a composite of metal fine particles 11 and finely divided cellulose 12 in which metal fine particles 11 and at least one or more finely divided cellulose 12 are combined. Yes, it can be used as a photothermal conversion material.
In this embodiment, as shown in FIG. 1, the composite 1 is a flat plate in which flat metal fine particles (flat metal fine particles) 11 and at least one or more refined cellulose are combined. Each of the finely divided celluloses 12 is at least partially (partially) or entirely incorporated into the flat metal fine particles 11 and the remainder is the flat metal fine particles 11. It is preferable to be composited so as to be exposed on the surface of the film.
Since the photothermal conversion molded body 2 to be described later contains the composite 1, the photothermal conversion molded body 2 that can selectively shield light in a specific wavelength region can be obtained, and the strength of the photothermal conversion molded body 2 is improved. Dimensional stability and gas barrier properties can be imparted and improved.

FIG. 2 is an observation image obtained by observing the composite 1 with uranyl staining and enlarged with a transmission electron microscope (TEM).
Fig.3 (a) is the observation image which observed the composite_body | complex 1 with the scanning electron microscope (SEM), (a) FIG.3 (b) is a schematic diagram of Fig.3 (a).
4A is an observation image obtained by magnifying and observing the composite 1 with a scanning transmission electron microscope (STEM), and FIG. 4B is a schematic diagram of FIG. 4A.
FIG. 5A is an observation image obtained by magnifying the composite 1 with a scanning electron microscope (SEM), and FIG. 5B is a schematic diagram of FIG.

  As shown in FIGS. 2 to 5, each refined cellulose 12 includes a portion (one end portion) 12 a taken in the flat metal fine particles 11 and a portion (others) exposed on the surface of the flat metal fine particles 11. End) 12b. Then, due to the presence of the one end portion 12 a taken into the flat metal fine particles 11, the flat metal fine particles 11 and the respective refined cellulose 12 are in an inseparable state. That is, the flat metal fine particles 11 and the refined cellulose 12 are physically at least partly obtained by incorporating at least a part (that is, one end portion 12a) of the refined cellulose 12 into the flat metal fine particles 11. Combined and inseparable.

  Here, in the composite 1, that at least a part (that is, one end portion 12 a) of the refined cellulose 12 is taken into the plate-like metal fine particles 11 in the growth stage of the plate-like metal fine particles 11. Is the same as the state in which the one end portion 12a of the micronized cellulose 12 is sandwiched.

  In the composite 1, the “inseparable” state means that it cannot be separated into the flat metal fine particles 11 and the fine cellulose 12 by a physical method such as a centrifuge. .

  In addition, the composite 1 includes a configuration in which all parts (the whole) of all the refined cellulose 12 are taken into the flat metal fine particles 11 and there are no exposed parts on the surface of the flat metal fine particles 11. It is. Also in the composite body 1 having such a configuration, as shown in FIG. 4, it is possible to confirm the presence of a portion (one end portion) 12 a that is taken into the flat metal fine particles 11 in the refined cellulose 12.

  The refined cellulose 12 is cellulose having at least one side of the structure of nanometer order, and the preparation method is not particularly limited. Usually, micronized cellulose has a fiber shape derived from a microfibril structure. Therefore, as the refined cellulose 12 in the composite 1, the above-described fibrous one is preferable. By using fibrous refined cellulose, the composite body 1 is controlled in shape and size. The details of the refined cellulose 12 will be described later.

(Observation of complex 1)
The observation of the complex 1 can be performed, for example, by the following method.
The composite 1 is purified by high-speed cooling centrifugation, etc., cast on a transmission electron microscope grid, stained with uranyl, and observed with a transmission electron microscope, so that a transmission electron microscope image as shown in FIG. 2 is obtained. can get. According to this transmission electron microscope image, it is possible to observe the flat metal fine particles 11 and the other end portion 12b of the refined cellulose 12 exposed on the surface thereof.

  The composite 1 was purified by high-speed cooling centrifugation, etc., and the resulting composite was cast on a silicon wafer plate and subjected to platinum deposition treatment, and then a scanning electron microscope (trade name: S-4800, Hitachi High-Technologies) By scanning), a scanning electron microscope image as shown in FIGS. 3 and 5 is obtained. According to this scanning electron microscopic image, it is possible to observe the flat metal fine particles 11 and the other end portion 12b of the refined cellulose 12 exposed on the surface thereof.

  Moreover, by purifying the complex produced by the method for producing complex 1 described later by high-speed cooling centrifugation or the like, casting the obtained complex 1 to a grid, and observing with the above-mentioned scanning transmission electron microscope A scanning transmission electron microscope image as shown in FIG. 4 is obtained. According to this scanning transmission electron microscope image, it is possible to observe the flat metal fine particles 11 and the one end refined cellulose 12a taken into the flat metal fine particles 11.

  In addition, the composite 1 is purified by high-speed cooling centrifugation, etc., and the obtained composite 1 is cast on a grid, and is observed with the above-mentioned scanning electron microscope in an undeposited state, followed by energy dispersive X-ray analysis The elemental mapping is performed, and the detection of carbon by the flat metal fine particles 11 and the refined cellulose 12 can confirm the composite of the flat metal fine particles 11 and the refined cellulose 12.

Generally, a metal surface and a solvent do not have a strong affinity, and particles will aggregate and precipitate as they are. However, the composite 1 is reduced in the presence of metal ions and micronized cellulose 12, whereby metal atoms are generated, and flat metal particles 11 are generated through nucleation and growth. In this process, it is considered that the flat metal fine particles 11 and the refined cellulose fibers interact to affect the form and aggregation of the flat metal fine particles 11, and the composite 1 having a controlled shape and particle diameter can be obtained. .
In the composite 1 thus obtained, at least a part or all of the refined cellulose 12 is taken into the flat metal fine particles 11 and the remaining part is exposed on the surface of the flat metal fine particles 11. In the composite 1, it is preferable that the flat metal fine particles 11 and the finely divided cellulose 12 are inseparable from the viewpoint of dispersion stability.

  Hereinafter, details of the flat metal fine particles 11 and the refined cellulose 12 will be described.

(Metal fine particles)
It is possible to control the wavelength region to be shielded by controlling the particle diameter and shape of the metal fine particles. Free electrons on the surface of the metal fine particles may collectively vibrate due to an external electric field such as light. Since electrons are charged particles, an electric field is generated around them when they vibrate. A phenomenon in which an electric field generated by free-electron vibration and an external electric field (light, etc.) resonates is called localized surface plasmon resonance (LSPR). By this LSPR, absorption or reflection of light in a specific wavelength region occurs and can be shielded. Compared with organic pigments generally used as color materials, metal fine particles have high stability and can stably shield a specific wavelength region over a long period of time.

  Among the metal nanoparticles having such an anisotropic shape, silver nanoparticles are particularly expected to be applied. For example, it is known that spherical silver nanoparticles having a particle diameter of several nanometers to several tens of nanometers have a yellowish color due to absorption in the vicinity of a wavelength of 400 nm by the LSPR. However, the anisotropically grown silver nanoparticles are not limited to this, and it is known that, for example, tabular silver nanoparticles are red-shifted in absorption peak. At this time, it has been confirmed that the absorption / reflection peak shifts to the longer wave side as the aspect ratio (that is, particle diameter / thickness) of the tabular silver nanoparticles increases. That is, the tabular silver nanoparticles can be used as an optical material that absorbs / reflects an arbitrary wavelength. Further, if the absorption / reflection wavelength is controlled in the visible light region, flat silver nanoparticles exhibiting a vivid color tone such as red and blue in addition to yellow can be obtained, and use as a functional color material can be expected. Further, depending on the aspect ratio of the tabular silver nanoparticles, the absorption peak can be shifted to the near infrared region outside the visible light region.

  The complex 1 strongly interacts with light in a specific wavelength region due to the effect of LSPR, and exhibits strong absorption. The light emission quantum yield of the flat metal fine particles 11 is extremely low, and the absorbed light energy is efficiently converted into heat energy. Also in the complex 1, the light absorbed by the effect of LSPR can be efficiently converted into heat energy.

In the present embodiment, visible light refers to an electromagnetic wave having a wavelength range of approximately 400 nm to 700 nm, and near infrared refers to an electromagnetic wave having a wavelength range close to visible light (approximately 700 nm to 2500 nm) among infrared rays. .
In particular, when absorption is present in the near-infrared region, both transparency and high photothermal conversion characteristics can be achieved. Therefore, in the transmittance spectrum of the composite dispersion, the transmittance is minimized in the wavelength region of 700 nm to 2500 nm. It preferably has a wavelength (λmax). The composite dispersion is a dispersion containing at least the composite 1 and a solvent. The complex dispersion liquid is sufficient if the complex is dispersed in a solvent. For example, the complex dispersion liquid refers to a dispersion liquid after the complex preparation reaction. Moreover, it may be diluted with a solvent such as pure water as necessary, and the solvent may be substituted if at least a part of the complex is dispersed.

  In the composite 1 of this embodiment, the metal fine particles are preferably flat metal fine particles 11, but the shape of the metal fine particles is not limited thereto. For example, the shape of the metal fine particles may be spherical, flat, or rod-shaped. In particular, from the viewpoint of controlling the resonance wavelength, the shape of the metal fine particles is preferably a flat plate shape or a rod shape, and more preferably a flat plate shape.

  The flat metal fine particles 11 are flat metal fine particles, and in the present embodiment, the fine particles are particles having a volume particle diameter of 10 μm or less.

Here, as shown in FIG. 1, the equivalent particle diameter (equivalent circle diameter) is calculated from the area when the shape of the front surface 13 or the rear surface 14 of the flat metal fine particle 11 of the composite 1 is approximated by a circle. Particle diameter. The particle diameter in the plane direction is referred to as particle diameter d. The particle diameter d is the particle diameter d of the composite 1. The length of the portion of the flat metal fine particle 11 perpendicular to the planar direction is defined as the thickness h of the composite 1.
The particle diameter d with respect to the thickness h of the flat metal fine particles 11 of the composite 1 is defined as the aspect ratio (d / h) of the composite 1. “Plate shape” of the plate-like metal fine particles 11 of the composite 1 indicates that the particles are plate-like, and the plate-like shape has an average aspect ratio (d / h) of 1. 1 or more.
In addition, although the shape of the surface 13 and the back surface 14 of the composite 1 is not specifically limited, Usually, they are polygons, such as a hexagon and a triangle. When the front surface 13 and the back surface 14 are polygons, ellipses, etc., the particle diameter d (circle equivalent particle diameter, circle equivalent diameter, diameter) is calculated assuming that the surface 13 or the surface 14 has an equivalent area. To do.
Moreover, the surface 13 and the back surface 14 of the composite 1 may have either large area, and both surfaces do not need to be parallel.

From the viewpoint of controlling the optical characteristics, the shape of the tabular metal fine particles 11 is preferably a tabular shape, and its particle diameter d, thickness h, and aspect ratio are preferably within the following ranges. In addition, the particle diameter d, thickness h, and aspect ratio of the flat metal fine particles 11 are equal to the particle diameter d, thickness h, and aspect ratio of the composite 1.
The average value of the particle diameter d of the tabular metal fine particles 11 is preferably 2 nm or more and 1000 nm or less, more preferably 20 nm or more and 500 nm or less, and further preferably 20 nm or more and 400 nm or less.
The average value of the thickness h of the flat metal fine particles 11, that is, the average value of the distance h between the front surface 13 and the back surface 14 is preferably 1 nm or more and 100 nm or less, and more preferably 5 nm or more and 50 nm or less.
In addition, said average value is calculated | required, for example by measuring 100 particle | grains.

  The average aspect ratio (average value of d / average value of h) of the plate-like fine metal particles 11 is preferably 1.1 or more, more preferably 2.0 or more and 100 or less, and 2.0 or more and 50 More preferably, it is as follows. In particular, an average aspect ratio of 4.0 or more and 20.0 or less is preferable because it can have absorption in the near infrared region.

  The composite 1 can change the color tone by arbitrarily changing the average value of the particle diameter d and controlling the average aspect ratio. Moreover, the composite body 1 should just contain the flat metal fine particle 11 and the refined cellulose 12, and may contain the other component.

The shape and size of the flat metal fine particles 11 can be evaluated using a scanning electron microscope, a transmission electron microscope, and a scanning transmission electron microscope.
Examples of the method for measuring the particle diameter d and thickness h of the flat metal fine particles 11 and the method for calculating the aspect ratio include the following methods.

(1) Measuring method of particle diameter d The dispersion liquid containing the composite 1 was cast on a copper grid with a support film for transmission electron microscope observation and air-dried, and then observed with a scanning transmission electron microscope. A scanning transmission electron microscope image as shown in FIG. The diameter of the flat metal fine particles 11 in the scanning transmission electron microscope image approximated by a circle is calculated as the particle diameter in the planar direction (particle diameter d). The average value is obtained by measuring 100 particles.

(2) Measuring method of thickness h As shown in FIG. 6, a dispersion containing the composite 1 was cast on a polyethylene terephthalate (PET) film 16, air-dried, and fixed with an embedding resin 17 with a microtome. By cutting in the cross-sectional direction and observing with a transmission electron microscope, a transmission electron microscope image as shown in FIG. 6 is obtained. FIG. 6 is a diagram (transmission electron microscope image) showing the result of observation of the flat metal fine particles 11 from the cross-sectional direction with a transmission electron microscope. The thickness h of the flat metal fine particles 11 in the transmission electron microscope is calculated as the thickness h perpendicular to the plane direction. The average value is obtained by measuring 100 particles.

(3) Aspect Ratio Calculation Method The average value of the particle diameter d (equivalent circle diameter, equivalent circle diameter, diameter) with respect to the average value of the thickness h of the plate-like fine metal particles 11 obtained as described above is calculated as a flat plate shape. The average aspect ratio of the metal fine particles 11 (average value of d / average value of h) is calculated.

  The method for measuring the particle diameter d and thickness h of the flat metal fine particles 11 and the method for calculating the aspect ratio are examples. The method for measuring the particle diameter d and thickness h of the flat metal fine particles 11 and the calculation of the aspect ratio. The method is not particularly limited to these.

  The method for measuring the transmittance spectrum of the complex dispersion liquid is not particularly limited, but the complex dispersion liquid after the complex preparation reaction is used as it is, or diluted with a solvent such as pure water as necessary and placed in a quartz cell, and then the spectrophotometer It can be measured using a meter.

The metal or metal compound which comprises the flat metal fine particle 11 is not specifically limited, Arbitrary metals or metal compounds can be used according to a use. Examples of the metal or metal compound constituting the flat metal fine particles 11 include gold, silver, copper, aluminum, iron, platinum, zinc, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, manganese, and vanadium. And metals such as molybdenum, gallium, and aluminum, metal salts, metal complexes and alloys thereof, oxides, and double oxides. Among them, it is preferable to include at least one of gold, silver, and copper. In particular, when at least silver is included, the composite 1 can shield light having a wavelength from the visible light region to the near infrared region, and has antibacterial properties. Can also be given.
The ratio of the metal contained in the composite 1 is not particularly limited.

(Micronized cellulose 12)
The refined cellulose 12 only needs to have a nanometer order on at least one side of the structure, and the preparation method is not particularly limited. Usually, since the refined cellulose has a fiber shape derived from a microfibril structure, the refined cellulose 12 used in the method for producing the composite 1 of the present embodiment is preferably a fiber in the following range. . By using the fibrous refined cellulose 12, it is possible to manufacture the composite body 1 whose shape and size are more controlled.

The refined cellulose 12 contained in the composite 1 can control the particle diameter and shape by controlling the growth of the flat metal fine particles 11 to be generated. Moreover, in the photothermal conversion molded body described later, it is possible to improve the dimensional stability as well as the strength of the photothermal conversion molded body 2.
From the viewpoint of improving transparency and strength, improving dimensional stability, and controlling the shape of the flat metal fine particles 11 in the composite 1, it is preferable that the minor axis diameter of the micronized cellulose 12 is sufficiently small.

  The kind of plant cellulose used as a raw material of the refined cellulose 12 is not particularly limited. As a raw material of the refined cellulose 12, for example, cotton linter, bamboo, hemp, bagasse, kenaf and the like can be used in addition to wood-based natural cellulose. Moreover, as a raw material of the refined cellulose 12, for example, non-wood type natural cellulose such as bacterial cellulose, squirt cellulose, and valonia cellulose, and regenerated cellulose represented by rayon fiber and cupra fiber can be used. Preferably, natural cellulose having crystalline form I is desirable because of its high material properties such as mechanical properties, thermal properties and chemical resistance.

Although it does not specifically limit as a refinement | purification processing method of a cellulose, For example, the method of refinement | miniaturizing using the chemical modification | denaturation and mechanical treatment of a cellulose other than the mechanical processing by a grinder is mentioned.
Bacterial cellulose can also be used as the refined cellulose 12. Further, finely regenerated cellulose fibers obtained by dissolving various natural celluloses in various cellulose solvents and then performing electrospinning may be used.
The chemical modification method of cellulose is not particularly limited. For example, N-oxyl compounds such as 2,2,6,6-tetramethyl-1-piperidine-N-oxy radical (hereinafter referred to as “TEMPO”) are used. The oxidation method, the dilute acid hydrolysis treatment, the enzyme treatment, and the like that have been used in combination with the mechanical treatment can be used.

The refined cellulose 12 is preferably chemically modified refined cellulose. The chemically modified finely divided cellulose is not particularly limited, but, for example, defibrate chemically modified cellulose such as carboxylated cellulose (hereinafter referred to as “oxidized cellulose”), carboxymethylated cellulose, and phosphate esterified cellulose. Can be obtained by:
In chemically modified micronized cellulose, the introduced functional groups such as carboxy group, carboxymethyl group, and phosphoric acid group serve as base points for the production of metal fine particles, and the shape and size of the composite can be easily controlled.

Carboxymethylated cellulose can be obtained from a cellulose raw material by a known method.
For example, an etherification agent such as monochloroacetic acid and a catalyst, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, is added to cellulose raw material, and water or a solvent mainly composed of lower alcohol such as methanol, ethanol, isopropyl alcohol, etc. It is obtained by reacting below. The carboxymethylated cellulose is sufficient if at least a part of glucopyranose is carboxymethylated, and the degree of substitution of carboxymethylcellulose is preferably 0.01 or more and 0.60 or less.

In particular, as shown in the method of Patent Document 1, in the oxidation reaction using an N-oxyl compound such as TEMPO, the primary hydroxyl group at the 6th position of the glucopyranose unit of the cellulose molecular chain on the crystal surface is highly selective. Oxidized cellulose that has been converted to a carboxy group via an aldehyde group can be obtained. Since an electrostatic repulsive force acts between celluloses having a carboxy group introduced on the crystal surface in this way, cellulose single nanofibers (hereinafter referred to as “CSNF”) dispersed to microfibril units in an aqueous medium. .) Can be obtained. Therefore, when CSNF is used, it is easy to control the shape and size of the composite.
The oxidation reaction using the N-oxyl compound will be described in detail later.

  If this CSNF is used, the composite 1 having a sufficiently controlled shape and size can be produced. CSNF, which is fibrous and has a uniform minor axis diameter, is suitable for controlling the particle diameter and shape of the flat metal fine particles 11 in the composite. CSNF regularly has carboxy groups on the fiber surface. This carboxy group is suitable for the production of the composite 1 because it is considered that the metal ion is coordinated to produce the composite 1 when the composite 1 is produced.

The viscosity characteristics of the micronized cellulose 12 are preferably as follows. 0.5 wt% dispersion of the fine cellulose 12 (25 ° C.) is, 30 mPa · s or more 2000 mPa · s or less at a shear rate of ^{1s -1, 20mPa} · s or more when shear rate of 100s ^-1 200 mPa -It is preferable that it is below s. More preferably, when the viscosity (25 ° C.) of the 0.5 mass% dispersion of fine cellulose is 100 mPa · s to 1000 mPa · s when the shear rate is 1 s ⁻¹ , and the shear rate is 100 s ⁻¹ . 30 mPa · s or more and 80 mPa · s or less.

  If the viscosity characteristics of the micronized cellulose 12 are within the above range, the micronized cellulose 12 has a low viscosity, so that it can be used at a high concentration, and the composite 1 can be produced with high productivity. If the viscosity characteristics are within the above range, the crystal structure and the surface structure are maintained, and the carboxy group is regularly used as a starting point for complexing with the metal fine particles, so that the complex is stably controlled in shape. 1 can be manufactured. Furthermore, if the viscosity characteristic is within the above range, the metal salt and the fine cellulose 12 can be uniformly mixed in the step b described later, and the reduction reaction can be promoted uniformly in the step c described later. .

The micronized cellulose 12 preferably has a minor axis number average axis diameter of 1 nm to 50 nm, a major axis number average axis diameter of 0.1 μm to 10 μm, and a minor axis number average axis diameter of 1 nm to 10 nm. Hereinafter, it is more preferable that the number average axis diameter of the major axis is 0.2 μm or more and 2 μm or less.
When the number average axis diameter of the minor axis of the micronized cellulose 12 is less than 1 nm, a highly crystalline rigid micronized cellulose structure cannot be obtained, and the composite 1 having a sufficiently controlled size and shape can be obtained. It becomes difficult. Moreover, it becomes difficult to obtain the photothermal conversion molded body 2 having good strength and dimensional stability.
On the other hand, when the number average axial diameter of the minor axis of the refined cellulose 12 exceeds 50 nm, the viscosity of the dispersion of the refined cellulose 12 is increased and the operability is deteriorated. 12 is difficult to mix uniformly, and in the step c described later, the reduction reaction cannot be progressed uniformly, and it is difficult to obtain the complex 1 whose size and shape are sufficiently controlled. Moreover, the transparency of the photothermal conversion molded body 2 may be reduced, and the strength may also be reduced.
If the number average axial diameter of the major axes of the micronized cellulose 12 is less than 0.1 μm, it is difficult to obtain the composite 1 having a controlled shape and size. On the other hand, if the number average axial diameter of the major axis of the fine cellulose 12 exceeds 10 μm, the viscosity of the dispersion of the fine cellulose 12 becomes high and the operability deteriorates. It becomes difficult to uniformly mix the modified cellulose 12, and the reduction reaction cannot be progressed uniformly in step c to be described later, and it is difficult to obtain the composite 1 whose size and shape are sufficiently controlled. Moreover, it becomes difficult to mix the resin and the complex-containing material obtained by concentrating the complex from the complex dispersion. Details of the composite-containing material will be described later.

  The minor axis number average axis diameter of the micronized cellulose 12 is determined by measuring the minor axis diameter (minimum diameter) of 100 fibers by transmission electron microscope observation and atomic force microscope observation, and obtaining the average value. On the other hand, the number average axis diameter of the major axis of the fine cellulose is obtained as an average value obtained by measuring the major axis diameter (maximum diameter) of 100 fibers by observation with a transmission electron microscope and observation with an atomic force microscope.

  Although the measuring method is not specifically limited about the short axis diameter of the refined cellulose 12, and a long axis diameter, For example, it can measure with the following method. A solution obtained by dispersing finely divided cellulose 12 in water so that the solid content concentration is in the range of 0.001 wt% or more and 0.01 wt% or less is developed on mica and dried naturally. Then, the minor axis diameter and major axis diameter of the refined cellulose 12 can be confirmed (measured) by observing the refined cellulose 12 with a transmission electron microscope.

  The crystallinity of the micronized cellulose 12 is preferably 70% or more. When the crystallinity of the micronized cellulose 12 is less than 70%, a rigid micronized cellulose structure cannot be obtained, and it becomes difficult to stably produce the composite 1, and the dimensional stability of the photothermal conversion molded body 2 is stabilized. The improvement effect and strength may be reduced.

The amount of carboxy groups in the finely divided cellulose 12 is preferably 0.1 mmol or more and 3.0 mmol or less, and more preferably 0.5 mmol or more and 2.0 mmol or less per 1 g of the dry weight of the fine cellulose 12.
When the amount of carboxy groups in the micronized cellulose 12 is less than 0.1 mmol / g, the dispersibility is poor, and when it is 0.1 mmol / g or more, the dispersion stability is improved due to electrostatic repulsion due to the carboxy groups. On the other hand, when the amount of carboxy groups in the refined cellulose 12 is 3.0 mmol / g or less, the crystal structure of the refined cellulose 12 is sufficiently retained, and the shape control performance is improved.

  When the cellulose fiber is dispersed to the microfibril unit, the light transmittance at a wavelength of 660 nm is increased. In a dispersion having a solid content concentration of 1%, the refined cellulose preferably has an optical path length of 1 cm, a wavelength of 660 nm, and a light transmittance of 80% or more using the dispersion medium as a reference. By using the micronized cellulose 12 having high transparency, the transparency of the photothermal conversion molded body 2 is increased.

  The refined cellulose 12 is not particularly limited, but those produced by the following oxidation process and refinement process can be used (a refined cellulose production process).

(Oxidation process)
Examples of natural cellulose used as a raw material for the finely divided cellulose 12 include wood pulp such as mechanical pulp, chemical pulp, and semi-chemical pulp. Specifically, bleached and unbleached kraft wood pulp, hydrolyzed kraft wood pulp, sulfite wood pulp, etc., as well as used paper, bacterial cellulose, valonia cellulose, squirt cellulose, cotton cellulose, hemp cellulose and mixtures thereof are used. be able to. Moreover, you may use any of the substance which processed these physically and chemically. It is preferable to use various wood pulps as a raw material from the viewpoint of ease of material procurement and price.

In the presence of an N-oxyl compound, as a method for oxidizing cellulose using a co-oxidant, alcoholic primary carbon is selectively oxidized while maintaining the crystal structure of cellulose as much as possible under relatively mild conditions in water. Is possible. Examples of the N-oxyl compound include TEMPO, 2,2,6,6-tetramethyl-4-hydroxypiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-N—. Examples include oxyl, 4-ethoxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamido-2,2,6,6-tetramethylpiperidine-N-oxyl. Among these, TEMPO is preferable.
The amount of the N-oxyl compound used is not particularly limited as long as it is an amount as a catalyst. Usually, the usage-amount of an N-oxyl compound is about 0.01 mass%-about 5.0 mass% with respect to the whole quantity of solid content of the wood type natural cellulose to oxidize.

  Examples of the method for oxidizing cellulose using an N-oxyl compound include a method in which wood-based natural cellulose is dispersed in water and oxidized in the presence of an N-oxyl compound. At this time, it is preferable to use a co-oxidant together with the N-oxyl compound. In this case, in the reaction system, the N-oxyl compound is sequentially oxidized by a co-oxidant to produce an oxoammonium salt, and cellulose is oxidized by the oxoammonium salt. According to such oxidation treatment, the oxidation reaction proceeds smoothly even under mild conditions, and the introduction efficiency of the carboxy group is improved. When the oxidation treatment is performed under mild conditions, it is easy to maintain the crystal structure of cellulose.

As a co-oxidant, halogen, hypohalous acid, halohalic acid or perhalogenic acid, or a salt thereof, halogen oxide, nitrogen oxide, peroxide, etc., as long as it can promote the oxidation reaction Any oxidizing agent can be used. From the standpoint of availability and reactivity, sodium hypochlorite is preferred as the co-oxidant.
The amount of the co-oxidant used is not particularly limited as long as it is an amount capable of promoting the oxidation reaction of cellulose. Usually, it is about 1% by mass to 200% by mass with respect to the total solid content of the wood-based natural cellulose to be oxidized.

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

The pH of the reaction system during the oxidation reaction of cellulose is preferably 9-11. When the pH is 9 or more, the reaction can be efficiently advanced. It is known that the oxidation efficiency by the N-oxyl compound is significantly reduced when the pH is out of the range. In the above oxidation treatment, as the oxidation proceeds, a carboxy group is generated, which lowers the pH in the reaction system. Therefore, the pH of the reaction system is preferably maintained at 9 to 11 during the oxidation treatment.
Examples of a method for maintaining the pH of the reaction system at 9 to 11 include a method of adding an alkaline aqueous solution in accordance with a decrease in pH.
Examples of the alkaline aqueous solution include sodium hydroxide aqueous solution, lithium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonia aqueous solution, tetramethylammonium hydroxide aqueous solution, tetraethylammonium hydroxide aqueous solution, tetrabutylammonium hydroxide aqueous solution, and benzyltrimethylammonium hydroxide. Examples include organic alkalis such as aqueous solutions. Among these, an aqueous sodium hydroxide solution is preferable from the viewpoint of cost and the like.

The reaction temperature of the oxidation reaction of cellulose is preferably 4 ° C. or higher and 50 ° C. or lower, and more preferably 30 ° C. or higher and 50 ° C. or lower.
The oxidation reaction itself with a normal N-oxyl compound proceeds sufficiently even in the region of 4 ° C. or higher and 50 ° C. or lower. It was found that the dispersion of finely divided cellulose 12 obtained as it was was reduced in viscosity. This is because the amorphous region periodically exists in the major axis direction of the cellulose microfibril, so that the oxidation reaction by the N-oxyl compound proceeds to the amorphous region, and the generated glucuronic acid unit has pH 9 in the reaction temperature region. It is considered that it is decomposed because it is unstable under the conditions of ˜11, and as a result, shortening of the fiber proceeds. When the reaction temperature exceeds 50 ° C., sodium hypochlorite self-decomposes due to side reaction, so that the oxidation reaction itself stops.

  The degree of oxidation in the oxidation treatment of cellulose can be appropriately set in consideration of the reaction temperature, the desired amount of carboxy groups, and the like. However, it is preferable that at least the amount of sodium hydroxide used in the oxidation reaction is 1.0 mmol / g or more and 5.0 mmol / g or less per dry weight of the natural cellulose used as a raw material. When the amount of sodium hydroxide added is less than 1.0 mmol / g, the amount of carboxy groups introduced is small, and sufficient electrostatic repulsion between microfibrils required for dispersion as CSNF cannot be obtained. On the other hand, if the amount of sodium hydroxide added exceeds 5.0 mmol / g, decomposition other than the amorphous region proceeds, the microfibril surface structure is lost, and the yield before and after the oxidation treatment is significantly reduced.

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

  The reaction solution after the oxidation treatment may be directly subjected to a refinement process, but in order to remove a catalyst such as an N-oxyl compound, impurities, etc., the oxidized cellulose contained in the reaction solution is recovered and washed with a washing solution. It is preferable. Oxidized cellulose can be collected by a known method such as filtration using a glass filter or a nylon mesh having a 20 μm pore size. Distilled water is preferable as the cleaning liquid used for cleaning the oxidized cellulose.

(Miniaturization process)
The micronization process is a process of obtaining a dispersion of micronized cellulose 12 by defibrating oxidized cellulose by light mechanical processing.
In the method of refining cellulose, first, a solvent is added to cellulose and suspended.
Although it does not specifically limit as a solvent, The thing similar to the solvent which disperse | distributes refined cellulose 12 can be used, Among these, water is especially preferable. If necessary, the pH of the suspension may be adjusted in order to improve the dispersibility of cellulose and the refined cellulose 12 to be produced. Examples of the alkaline aqueous solution used for adjusting the pH include the same alkaline aqueous solution as mentioned in the description of the oxidation step of oxidized cellulose.

Subsequently, the cellulose is refined by subjecting the suspension to physical defibrating treatment.
Examples of physical fibrillation treatment include high-pressure homogenizer, ultra-high-pressure homogenizer, ball mill, roll mill, cutter mill, planetary mill, jet mill, attritor, grinder, juicer mixer, homomixer, ultrasonic homogenizer, nanogenizer, underwater collision And other mechanical treatments. By performing such physical fibrillation treatment on, for example, TEMPO oxidized cellulose, the cellulose in the suspension is refined, and a dispersion of CSNF having a carboxy group on the fiber surface can be obtained.

Since the refined cellulose 12 obtained as described above maintains the crystal structure, the composite 1 can be produced stably.
The obtained dispersion liquid can be used as a reaction field for reducing and precipitating metal fine particles as it is, or by diluting, concentrating, solvent substitution and the like as necessary.
The dispersion liquid of the refined cellulose 12 may contain other components other than the components used for adjusting the cellulose and the pH as long as the effects of the present embodiment are not impaired. Other components are not particularly limited, and can be appropriately selected from known additives depending on the application.
Specifically, as other components, organometallic compounds such as alkoxysilanes or hydrolysates thereof, inorganic layered compounds, inorganic needle minerals, antifoaming agents, inorganic particles, organic particles, lubricants, antioxidants Agents, antistatic agents, ultraviolet absorbers, stabilizers, magnetic powders and the like. The composite 1 may be produced after mixing the aqueous dispersion component and the aqueous emulsion component with the finely divided cellulose dispersion.

[Method for producing composite 1]
Although the manufacturing process (complex preparation process) of the composite 1 is not specifically limited, For example, the process a, the process b, and the process c shown below are provided.
Step a is a micronized cellulose-containing liquid preparation step in which a solution or dispersion containing at least one type of micronized cellulose 12 is prepared and a micronized cellulose-containing liquid is prepared.
Step b includes preparing a solution or dispersion liquid containing at least one kind of metal salt and at least one kind of micronized cellulose 12, and preparing a metal salt and a micronized cellulose-containing liquid. It is a liquid preparation process.
Step c is a reaction solution preparation step in which metal ions in the metal salt and the refined cellulose-containing solution are reduced to prepare a reaction solution to obtain a composite dispersion.

  The refined cellulose 12 used for producing the composite is preferably chemically modified refined cellulose. Since the metal ion is reduced in a state where the metal ion is coordinated to the functional group introduced by the chemical modification and the metal fine particles are generated based on the metal ion, the composite and shape control are facilitated.

(Process a: Refined cellulose dispersion preparation process)
In the manufacturing method of the composite body 1, in step a, at least one type of fine cellulose dispersion is prepared.

The solid content concentration of the refined cellulose dispersion in at least one kind of refined cellulose dispersion is not particularly limited, but is preferably 0.01% by mass or more and 90% by mass or less, and more preferably 0.1% by mass or more and 50% by mass. % Or less is more preferable.
When the solid content concentration of the fine cellulose dispersion is less than 0.01% by mass, it is difficult to control the shape of the composite 1. On the other hand, when the solid content concentration of the fine cellulose dispersion exceeds 90% by mass, the viscosity of the fine cellulose dispersion increases, and in step b (metal salt and fine cellulose-containing liquid preparation step), metal salt and fine It becomes difficult to mix the cellulose acetate 12 uniformly, and the reduction reaction cannot be progressed uniformly in step c (reaction liquid preparation step).

The solvent in which the fine cellulose 12 is dispersed is not particularly limited as long as the fine cellulose 12 is sufficiently dissolved or dispersed. From the viewpoint of environmental load, it is preferable to use water as the solvent.
From the viewpoint of dispersibility of the flat metal fine particles 11 and the refined cellulose 12, it is preferable to use water or a hydrophilic solvent as the solvent. Although it does not specifically limit as a hydrophilic solvent, Alcohols, such as methanol, ethanol, isopropanol, are preferable.

  The pH of at least one type of fine cellulose dispersion is not particularly limited, but is preferably pH 2 or more and pH 12 or less.

(Process b: Metal salt and refined cellulose containing liquid preparation process)
In the production method of the composite 1, in step b, a solution or dispersion containing at least one type of metal salt and at least one type of refined cellulose 12 is prepared, and a metal salt and a refined cellulose-containing solution are prepared. .

  The method for preparing a solution or dispersion containing at least one metal salt and at least one micronized cellulose 12 is not particularly limited. For example, a solution or dispersion containing at least one type of micronized cellulose 12 (a micronized cellulose dispersion) and a solution containing at least one type of metal salt (a metal salt-containing solution) are prepared. It can be prepared by adding the metal salt-containing solution to the finely divided cellulose dispersion while stirring the dispersion. Further, a solid metal salt may be added directly to the fine cellulose dispersion, or the fine cellulose dispersion may be added to the metal salt-containing solution.

  As the metal salt, from the group consisting of silver nitrate, silver chloride, silver oxide, silver sulfate, silver acetate, silver nitrite, silver chlorate, chloroauric acid, sodium gold chloride, potassium gold chloride, platinum chloride, platinum oxide and platinum oxide It is preferable that there is at least one selected. These metal salts may be used individually by 1 type, and may be used in combination of 2 or more types.

When preparing a metal salt-containing solution, the solvent used in the metal salt-containing solution is not particularly limited as long as the metal salt is sufficiently dispersed or dissolved.
From the viewpoint of environmental load, it is preferable to use water as the solvent.
From the viewpoint of solubility of the metal salt, it is preferable to use water or a hydrophilic solvent as the solvent. Although it does not specifically limit as a hydrophilic solvent, Alcohols, such as methanol, ethanol, isopropanol, are preferable.
Further, the concentration of the metal salt in the metal salt-containing solution is not particularly limited.

  The concentration of the metal salt and the metal salt in the fine cellulose dispersion is not particularly limited, but is preferably 0.002 mmol / L or more and 20.0 mmol / L or less. In particular, when CSNF is used as the micronized cellulose 12, the metal ion is coordinated to the carboxy group present on the fiber surface, so the metal salt concentration (metal ion concentration) is adjusted to be less than the carboxy group amount. It is preferable. If the concentration of metal salt (concentration of metal ions) exceeds the amount of carboxy groups present on the surface of the refined cellulose 12, CSNF may aggregate.

The solvent used for the metal salt and the refined cellulose-containing liquid is not particularly limited as long as the refined cellulose 12 is sufficiently dispersed or dissolved.
From the viewpoint of environmental load, it is preferable to use water as the solvent.
From the viewpoint of the dispersibility of the complex 1, it is preferable to use water or a hydrophilic solvent as the solvent. Although it does not specifically limit as a hydrophilic solvent, Alcohols, such as methanol, ethanol, isopropanol, are preferable.

The solid content concentration of the refined cellulose 12 in the metal salt and the refined cellulose dispersion is not particularly limited, but is preferably 0.01% by mass or more and 90% by mass or less, and 0.1% by mass or more and 50% by mass or less. It is more preferable that
If the solid content concentration of the micronized cellulose 12 is less than 0.01% by mass, it is difficult to control the shape of the composite 1. On the other hand, when the solid content concentration of the refined cellulose 12 exceeds 90% by mass, the viscosity of the refined cellulose dispersion increases, and it becomes difficult to uniformly mix the metal salt and the refined cellulose 12 in step b. In step c, the reduction reaction cannot proceed uniformly. When the composite is used as a conductive material, it becomes difficult to sinter at a low temperature when the solid content concentration of the micronized cellulose 12 becomes high, and a step of removing the micronized cellulose 12 is necessary.

The solvent of the metal salt and the refined cellulose-containing liquid is not particularly limited as long as the refined cellulose 12 is sufficiently dissolved or dispersed.
From the viewpoint of environmental load, it is preferable to use water as the solvent.
From the viewpoint of dispersibility of the flat metal fine particles 11 and the refined cellulose 12, it is preferable to use water or a hydrophilic solvent as the solvent. Although it does not specifically limit as a hydrophilic solvent, Alcohols, such as methanol, ethanol, isopropanol, are preferable.

The pH of the metal salt and the refined cellulose-containing liquid is not particularly limited, but is preferably pH 2 or more and pH 12 or less.
The temperature of the metal salt and the refined cellulose-containing liquid is not particularly limited, but when water is used as the solvent, it is preferably 4 ° C. or higher and 100 ° C. or lower.

(Process c: Reaction liquid preparation process)
In the manufacturing method of the composite body 1, in step c, metal ions in the metal salt and the fine cellulose-containing liquid are reduced to prepare a reaction liquid to obtain a composite dispersion.

  The method for reducing the metal ions in the metal salt and the refined cellulose-containing liquid is not particularly limited, and a known method can be used. For example, a method using a reducing agent, ultraviolet rays, electron beams, liquid plasma, or the like can be employed. A known reducing agent can be used as a reducing agent used for reducing metal ions.

  Examples of the reducing agent include metal hydride-based, borohydride-based, borane-based, silane-based, hydrazine and hydrazide-based reducing agents. In general, in the liquid phase reduction method, sodium borohydride, dimethylamine borane, sodium citrate, ascorbic acid and alkali metal ascorbate, hydrazine, and the like are used as the reducing agent.

The amount of reducing agent added in the metal salt and refined cellulose-containing liquid (reducing agent concentration) is not particularly limited, but should be equal to or greater than the concentration of metal salt and metal salt in the refined cellulose-containing liquid. Is preferable, and more preferably 0.002 mmol / L or more and 2000 mmol / L or less.
If the concentration of the reducing agent in the metal salt and the refined cellulose-containing liquid is equal to or less than the concentration of the metal salt in the metal salt and the refined cellulose-containing liquid, unreduced metal ions remain in the metal salt and the refined cellulose-containing liquid. Resulting in.

Although there is no particular limitation on the method of adding the reducing agent in the case of reducing the metal ion in the liquid containing the metal salt and the refined cellulose using the reducing agent, the reducing agent is dissolved or dispersed in a solvent such as water in advance, The solution or dispersion may be added to the metal salt and refined cellulose-containing solution.
Moreover, the addition rate of the reducing agent with respect to the metal salt and the refined cellulose-containing liquid is not particularly limited, but it is preferably added by a method in which the reduction reaction proceeds uniformly.

  In addition, although the manufacturing method of the composite_body | complex 1 is not specifically limited, It is preferable that the above-mentioned process a, process b, and process c are included at least. Another process may enter between each process.

  In the composite 1, it is preferable that at least a part of the surface of the composite 1 is coated with a semiconductor, a metal, or a metal oxide thereof. By covering the surface of the composite 1, the stability can be further improved. . The semiconductor or metal used for the coating and its oxide are not particularly limited. For example, gold, silver, copper, aluminum, iron, platinum, zinc, palladium, ruthenium, iridium, rhodium, osmium, chromium, cobalt, nickel, Examples thereof include metals such as manganese, vanadium, molybdenum, gallium, and aluminum, metal salts, metal complexes, and alloys thereof, or oxides, double oxides, and silica. In particular, it is preferable to coat gold and silica from the viewpoint of stability and versatility.

Although not particularly limited, the composite may be fractionated and concentrated as necessary from the composite dispersion when the photothermographic product is produced. When the amount of the solvent is excessive, the concentration of the photothermal conversion composition described later becomes low. For example, when producing a sheet-like molded product, energy is required to remove the solvent, and productivity is poor. By concentrating the composite, the solid content concentration of the photothermal conversion composition is increased, and the amount of the solvent in producing the molded body is reduced. Therefore, the molded body can be produced efficiently. Examples of the fractionation / concentration method include centrifugation, gel filtration column, gel electrophoresis, lyophilization, ultrafiltration, precipitation, and the like. A plurality of fractionation and concentration methods may be combined. Hereinafter, the complex dispersion and the complex recovered by fractionation or concentration are referred to as a complex-containing material.
When micronized cellulose is concentrated by centrifugation, it must be concentrated with an ultracentrifuge, but the plate-like silver / micronized cellulose composite (composite) settles because high-density metals are bound. The coefficient becomes high, and it is possible to concentrate very efficiently as compared with the case of using the finely divided cellulose dispersion alone. For this reason, it is possible to reduce the ratio of the solvent of the photothermal conversion composition, and it becomes possible to obtain a molded object efficiently.

[Production Method of Photothermal Conversion Molded Body 2]
Hereinafter, the manufacturing method of the photothermal conversion molded object 2 which concerns on this embodiment is demonstrated. The photothermal conversion molded body 2 is not particularly limited, but can be formed by coating the photothermal conversion composition on a substrate or the like, removing the solvent, and if necessary, a curing reaction. The photothermal conversion molded body 2 can also be obtained as a self-supporting film by forming a photothermal conversion composition on a substrate and then peeling it.
The photothermal conversion composition according to this embodiment is a photothermal conversion composition containing at least the composite 1.

  The method for preparing the photothermal conversion composition is not limited as long as at least the complex-containing material and the resin are sufficiently dissolved or dispersed within a range not causing trouble. Each may be prepared and mixed in advance as a solution or dispersion. For example, the complex-containing material may be added to the resin dispersion or solution, or the resin may be added in the complex-containing dispersion to prepare a solution. In addition, various materials such as resins and cross-linking agents may be heated in the preparation stage in order to increase dispersibility in the solution. The complex-containing material refers to a complex dispersion and a concentrate obtained by concentrating the complex.

  You may perform a dispersion | distribution process as needed. Examples of the dispersion treatment include homomixer treatment, mixer treatment with a rotary blade, high pressure homogenizer treatment, ultrahigh pressure homogenizer treatment, ultrasonic homogenizer treatment, nanogenizer treatment, disc type refiner treatment, conical type refiner treatment, double disc type refiner treatment, There are grinder processing, ball mill processing, kneading processing with a biaxial kneader, underwater facing processing, and the like. Among these, the mixer treatment with a rotary blade, the high-pressure homogenizer treatment, the ultra-high pressure homogenizer treatment, and the ultrasonic homogenizer treatment are preferable from the viewpoint of miniaturization efficiency. Of these processes, two or more processing methods can be combined and distributed.

Here, the solid content of the composite-containing material in the photothermal conversion composition is preferably 0.1% by mass or more and 50% by mass or less, and more preferably 5% by mass or more and 30% by mass or less. When the solid content of the composite is less than 0.1% by mass, the characteristics such as sufficient low linear expansion and high elastic modulus cannot be exhibited. On the other hand, if it exceeds 50% by mass, the brittleness becomes prominent due to the rigidity of the refined cellulose, and the processing / moldability of the molded article deteriorates.
Further, the solid content of the metal contained in the photothermal conversion composition is preferably 0.0001 mass% or more and 50.00 mass% or less, and preferably 0.01 mass% or more and 10 mass% or less. . If the solid content of the metal is within this range, the photothermal conversion characteristics are sufficiently exhibited.

Although the solvent of a photothermal conversion composition is not specifically limited, It is preferable that water is included from a dispersible viewpoint of a composite_body | complex. Further, a known solvent other than water may be included. From the viewpoint of dispersibility of the complex 1, it is preferable to use a hydrophilic solvent as the solvent. Although it does not specifically limit as a hydrophilic solvent, Alcohols, such as methanol, ethanol, isopropanol, are preferable.
Of these solvents, ethanol is preferred.

Although there is no restriction | limiting in particular as a method of forming the photothermal conversion molded object 2 using the photothermal conversion composition prepared in this way, Since the photothermal conversion composition has fluidity | liquidity, it is a resin base material or a glass group. The photothermal conversion molded body 2 can be obtained by wet coating on a support such as a material, drying, and curing as necessary.
As a coating method, a known method can be used. Specifically, bar coating, dip coating, spin coating, flow coating, spray coating, roll coating, gravure roll coating, air doctor coating, blade coating, wire doctor coating, knife coating Methods, reverse coating method, transfer roll coating method, micro gravure coating method, kiss coating method, cast coating method, slot orifice coating method, calendar coating method, die coating method and the like can be used.

  The substrate (support) 23 for forming the photothermal conversion molded body 2 is not particularly limited, and paper, nonwoven fabric, glass substrate, plastic substrate, or the like can be used according to the purpose.

  For the purpose of improving the wettability and adhesion of the substrate 23 to which the photothermal conversion composition is applied, the substrate 23 may be pretreated. The pretreatment method is not particularly limited. For example, an anchor layer may be formed in advance, or corona treatment, plasma treatment, flame treatment, or the like may be performed.

Next, a method for producing the photothermal conversion molded body 2 will be described. For example, the photothermal conversion composition is applied onto the base material 23 using the above-described method, heated with light irradiation such as infrared rays or hot air to remove the solvent, and when a cross-linking agent is included, a cross-linking reaction with the cross-linking agent. Promote. A molded body as a self-supporting film can be formed by removing the support as necessary.
The reactivity of the crosslinking reaction varies depending on the heating temperature, and the temperature is preferably 100 ° C. or higher, preferably 120 ° C. or higher. However, when the treatment is carried out at 160 ° C. or higher, the decomposition of the cellulose fibers proceeds and the deterioration of the properties of the molded product causes yellowing.
When a photothermal conversion composition containing a photocurable resin and a photopolymerization initiator is applied, after removing the solvent by heating, light having a wavelength that allows the polymerization reaction to proceed, for example, ultraviolet light (UV) or visible light (Vis) And cured by irradiation with infrared light (IR).
The progress of the polymerization reaction or the formation of a crosslinked structure by heating or light irradiation is referred to as curing, the curing by heat is thermosetting, and the curing by light is photocuring.

[Photothermal conversion composition, photothermal conversion molding 2]
FIG. 7 is a diagram schematically showing the photothermal conversion molded body 2 according to the present embodiment. The photothermal conversion molded body 2 is a molded body including the composite body 1. The photothermal conversion molded body 2 can be manufactured using a photothermal conversion composition containing the composite 1.

(resin)
Since the photothermal conversion composition containing at least the composite 1 contains the finely divided cellulose 12, the photothermal conversion molded body 2 can be produced using the photothermal conversion composition without containing a resin. The photothermal conversion composition including the composite body 1 and the photothermal conversion molded body 2 may include a resin 21 in order to control the characteristics thereof. The resin 21 is not particularly limited, and a known resin can be used. In particular, it is preferable to use a water-soluble polymer, an aqueous emulsion, an aqueous dispersion, a resin obtained by curing a photocurable material, or the like. . You may knead | mix to a thermoplastic resin etc.

(A) Water-soluble polymer At 85 ° C., the water-soluble polymer is an alcohol aqueous solution containing 50% by mass of methanol, ethanol, propanol or isopropyl alcohol, and 100 parts by mass of a solvent containing at least one of water. On the other hand, it is a compound having a molecular weight of 1000 or more that dissolves 1 part by mass or more.
Examples of the water-soluble polymer include proteins, vinyl resins, acrylic resins, polyethylene resins, urethane resins, and epoxy resins.
Examples of proteins include gelatin, casein, and sodium chondroitin sulfate.
Examples of the vinyl resin include polyvinyl alcohol, polyvinyl pyrrolidone, and polyvinyl pyrrolidone / vinyl acetate copolymer.
Examples of the acrylic resin include sodium polyacrylate, carboxyvinyl polymer, polyacrylamide, and acrylamide / acrylate copolymer.
Examples of the polyethylene resin include polyethyleneimine, polyethylene oxide, polyethylene glycol, and the like.
Only one type of water-soluble polymer may be used, or two or more types may be used.

  From the viewpoint of the dispersibility of the composite 1 and the strength and dimensional stability of the photothermal conversion molded body 2, it is particularly preferable to use a polyvinyl alcohol (PVA) polymer. As the PVA-based resin, it is preferable to use an unmodified PVA resin typified by a saponified product of vinyl acetate homopolymer. However, as long as the effect of the present embodiment is not hindered, the vinyl ester in vinyl acetate is used. On the other hand, other vinyl compounds may be copolymerized.

  The degree of polymerization of the PVA polymer is not particularly limited, but is preferably from 300 to less than 3000, and more preferably from 500 to less than 2500. When the degree of polymerization is less than 300, the interaction between PVA molecules is lowered, which may lead to a decrease in mechanical properties. In addition, when the degree of polymerization is greater than 3000, the viscosity of the coating liquid becomes too high, the film thickness of the photothermal conversion molded body 2 becomes non-uniform, and it becomes difficult to remove the dispersion medium during the drying process. It becomes difficult.

  The degree of saponification of the PVA polymer is preferably 90 mol% or more and less than 100 mol%, and more preferably 95 mol% or more and less than 100 mol%. When the degree of saponification is less than 90 mol%, hydrogen bonds in the PVA polymer molecules due to the hydroxyl groups are lowered, and the mobility of the molecules becomes particularly active at high temperatures, which easily causes thermal deformation. Moreover, it is difficult to obtain a saponification degree of 100 mol% in the production process.

  In the present embodiment, the photothermal conversion composition containing the composite 1 preferably contains a crosslinking agent. It is preferable to obtain the photothermal conversion molded body 2 having desired characteristics by forming a crosslinked structure with the PVA polymer. That is, by forming a crosslinked structure, it is possible to exhibit characteristics such as high mechanical characteristics, retention of a low coefficient of linear expansion at high temperatures, and significant improvement in water resistance. As a crosslinking agent used for this embodiment, it is preferable to raise | generate a crosslinking reaction at least with a PVA-type polymer, and what raise | generates a crosslinking reaction also with a cellulose fiber is more preferable.

  The crosslinking agent used in this embodiment is a polymer having a molecular weight of 10,000 or more and less than 5,000,000. More preferably, a molecular weight of 50,000 or more and less than 1,000,000 is more suitably used. If the molecular weight is too small, it becomes difficult to form a three-dimensional structure together with the PVA polymer, and it becomes difficult to incorporate micronized cellulose having a rigid shape into the crosslinked structure. In this case, it is difficult to achieve water resistance and a low coefficient of linear expansion at high temperatures. Furthermore, if the molecular weight is too large, it is difficult to dissolve uniformly, and handling becomes difficult. Moreover, since the access frequency of the active site in the reaction system, that is, the carboxylic acid and the hydroxyl group is lowered, the reactivity is lowered.

A crosslinking agent is not specifically limited, A well-known crosslinking agent can be used. For example, as a crosslinking agent that forms a crosslinked structure by heating, oxazoline, divinylsulfone, carbodiimide, dihydrazine, dihydrazide, epichlorohydrin, glyoxal, an organic titanium compound, an organic zirconium compound, or the like can be used.
Among these, a crosslinking agent having a carboxylic acid or a carboxylic acid anhydride having good reactivity based on the hydroxyl group contained in the PVA polymer and the hydroxyl group of the cellulose fiber is preferable. A strong cross-linked structure is formed by the reaction between the hydroxyl groups of the PVA polymer or cellulose fiber and the carboxylic acid contained in the cross-linking agent. The said crosslinking agent may be used individually by 1 type, and may use 2 or more types together.

The addition rate of the crosslinking agent in the case of adding the crosslinking agent is not limited as long as the effect of the present embodiment is not impaired, but the solid content in the photothermal conversion composition is 0.01% by mass or more and 20% by mass or less. It is preferable that
When a crosslinking agent having a carboxylic acid or a carboxylic acid anhydride is used, the number of functional groups of the carboxylic acid is preferably 1% or more and less than 50%, more preferably 5% with respect to the number of functional groups of the hydroxyl group in the photothermal conversion composition. It can be suitably used when it is less than 20%. That is, when there are too few crosslinking agents containing carboxylic acid, a crosslinked structure will not fully develop and the effect of a crosslinking agent will fall. If the amount is too large, the excess cross-linking agent that does not proceed with the reaction may cause a reduction in characteristics, and hydrogen bonds between hydroxyl groups in the molded body may decrease, resulting in a decrease in characteristics of various species.

(B) Photocurable resin Moreover, the photothermal conversion composition containing the composite 1 can contain a photocurable material and a photopolymerization initiator. After coating the photothermal conversion composition, a molded body containing a cured resin can be obtained by removing the solvent and irradiating with light.
As the photocurable material, it is preferable to use a material such as a photo radical curing system or a photo cation curing system.
Examples of the photo-radical curing system include acrylic materials, which are synthesized from (meth) acrylate compounds such as acrylic acid or methacrylic acid ester of alcohol, diisocyanate and alcohol, and hydroxyester of acrylic acid or methacrylic acid. Such urethane (meth) acrylate compounds can be used.
Further, polyether resins having an acrylate functional group, polyester resins, epoxy resins, alkyd resins, spiroacetal resins, polybutadiene resins, polythiol polyene resins, and the like can be used. In addition, polyfunctional here means having a functional group which has activity by two or more light irradiation in a molecule | numerator.

  As the photopolymerization initiator, acetophenones, benzoins, benzophenones, phosphine oxides, ketals, anthraquinones, and thioxanthones can be used. Moreover, the addition amount of a photoinitiator is 0.1 weight part-10 weight part with respect to 100 weight part of photocurable compounds, Preferably it is 1 weight part-7 weight part, More preferably, it is 1 weight part-5 weight. Part.

(C) Aqueous Dispersion and Aqueous Emulsion The aqueous dispersion and the aqueous emulsion are sometimes called an aqueous dispersion and an aqueous emulsion, respectively, and are aqueous resins dispersed in an aqueous dispersion medium containing water. These aqueous dispersions and aqueous emulsions are those in which water is used as a main dispersion medium and a polymer is dispersed in a particle size of submicron to several microns. By volatilizing these dispersion media, the polymers are deformed and fused to form a continuous structure.

  Aqueous dispersions and aqueous emulsions have the advantage that the degree of freedom in design is higher than that of water-soluble monomers and water-soluble oligomers as a resin, and materials can be selected according to the intended performance and function. Furthermore, although the dispersion stability in a dispersion medium is provided by addition of an emulsifier or introduction of a hydrophilic group into the resin, the synthetic resin itself is hydrophobic and has high water resistance and moisture resistance. Therefore, it is difficult to be influenced by the external humidity environment, and when the moisture content is changed as the photothermal conversion molded body 2, there is no significant deformation, and the structure as the photothermal conversion molded body 2 can be maintained.

  In addition, aqueous dispersions and aqueous emulsions have a high degree of polymerization of the resin, but the resin forms individual fine particles, so that the viscosity as a coating liquid is low. Therefore, even if the composite-containing material that is a constituent material of the present embodiment has a high viscosity, good mixing properties can be obtained.

  Aqueous dispersions and aqueous emulsions are roughly classified into anionic, cationic and nonionic properties depending on ionicity. In the present embodiment, any use is not limited. However, when the micronized cellulose 12 of the complex 1 to be mixed is anionic, mixing with a cationic resin may inhibit the charge, so anionic or Nonionic properties are preferred.

Examples of the resin composed of an aqueous dispersion or an aqueous emulsion include vinyl acetate, urethane, acrylic, styrene, phenol, amino, amide, polyester, ethylene, and polyvinyl alcohol. These may be used alone, or may be copolymerized or used in combination of two or more.
Also, a reactive synthetic resin may be used. In that case, for example, a curing agent, a curing catalyst, a photopolymerization initiator, a chain transfer agent, and the like can be used in combination.

Here, the solid content rate (solid content rate of the cellulose component and the metal component) of the composite-containing material (composite dispersion or composite concentrate) in the photothermal conversion molded body 2 is 0.1% by mass or more and 50% by mass. % Or less, more preferably 10% by mass or more and 30% by mass or less. When the solid content of the composite is less than 1% by mass, characteristics such as sufficient low linear expansion, water resistance, and high modulus cannot be exhibited. Moreover, when it exceeds 50 mass%, the brittleness derived from the rigidity of micronized cellulose will become obvious, and the processing and moldability of a molded object may worsen.
Moreover, it is preferable that the solid content rate of the metal contained in the photothermal conversion molded object 2 is 0.0001 mass% or more and 50.00 mass% or less, and it is 0.01 mass% or more and 10 mass% or less. preferable. If the solid content of the metal is within this range, the photothermal conversion characteristics are sufficiently exhibited.

  The thickness T of the photothermal conversion molded body 2 obtained in this embodiment is preferably in the range of 1 μm to 500 μm, more preferably in the range of 10 μm to 200 μm, and particularly preferably in the range of 20 μm to 100 μm. When the thickness T is less than 1 μm, the strength of the molded body becomes extremely weak and unsuitable for production. On the other hand, if the thickness exceeds 500 μm, the drying speed is very long, and the productivity is extremely lowered, and excessive moisture remains in the photothermal conversion molded body 2, which is not preferable.

Since the composite 1 has a high sedimentation coefficient, it can be efficiently concentrated by centrifugation or the like, and a high-concentration composition can be obtained with high productivity. Less energy is required. For this reason, a thick molded body having high strength and excellent dimensional stability can be efficiently produced.
In addition, due to the photothermal conversion characteristics of the composite 1, even in the thick photothermal conversion molded body 2, the irradiation effect of various lamps such as an infrared lamp can be further promoted, and the coating film can be dried and thermally cured. In addition, when a photo-curable resin is included, when irradiating a lamp such as infrared rays before and after irradiation with UV light or the like, effects such as uniform reaction promotion, improvement of scratch resistance by stress relaxation, curl suppression, etc. Can be further improved.

  Since the refined cellulose 12 of the composite 1 in the photothermal conversion molded body 2 is highly dispersed in the photothermal conversion molded body 2, the transmittance in the visible light region is increased and high transparency is obtained. In particular, by using the composite 1 having absorption in the near infrared region having a wavelength of 700 nm or more and 2500 nm or less, the photothermal conversion molded body 2 having both high photothermal conversion characteristics and visible light transmittance can be obtained. The photothermal conversion molded body 2 preferably has a light transmittance at 660 nm of 50% or more, more preferably 70% or more.

  By using the above-mentioned method, it becomes possible to form the photothermal conversion molded body 2 with a resin while maintaining a highly dispersed state of the composite 1 that has been difficult in the past. The photothermal conversion molded body 2 utilizing the photothermal conversion characteristics and the excellent reinforcing characteristics and low linear expansion characteristics derived from the refined cellulose can be obtained.

  The photothermal conversion molded body 2 may contain various additives as necessary. For example, chemically modified cellulose, carrageenan, xanthan gum, guar gum, gum arabic, sodium alginate, agar, solubilized starch, glycerin, sorbitol, antifoaming agent, water-soluble polymer, synthetic polymer and the like can be included. Various dyes, pigments, organic fillers, inorganic fillers and the like may be included for the purpose of imparting design properties. In addition, for the purpose of improving moldability and suppressing deterioration, improving the dispersibility of optical materials, etc., heat stabilizers, stabilizing aids, plasticizers, antioxidants, light stabilizers, flame retardants, lubricants, antistatic agents May be included.

[Photothermal conversion characteristics of photothermal conversion molded body 2]
Next, the photothermal conversion characteristics of the photothermal conversion molded body 2 are measured and the results are shown.

  The method for measuring the transmission spectrum is not particularly limited, but can be measured by the following method. The reference was measured in the sky, and the light transmittance of the photothermal conversion molding 2 was measured with a spectrophotometer UV-3600 (manufactured by Shimadzu Corporation) from a wavelength of 220 nm to 2500 nm. The wavelength at which the light transmittance is minimized from the obtained light transmittance is defined as λmax (nm) of the photothermal conversion molded body 2.

A dispersion of one example of complex 1 (complex A and complex B) was prepared using CSNF, and a complex A-containing material and a complex B-containing material were obtained by concentration by centrifugation. As a base material, a PET film having a thickness of 25 μm (hereinafter sometimes referred to as a PET base material) is subjected to corona treatment, and the composite A-containing material and the composite B-containing material are coated and heated using a bar coater. A photothermal conversion molded body 2 having a composite layer having a thickness of about 1 μm obtained by drying was produced.
As a reference, a molded body in which a CSNF layer having a film thickness of about 1 μm was provided on a PET substrate was produced.

FIG. 8 is a diagram showing a result of observing an example of the complex 1 (complex A, λmax = 906 nm) with a scanning transmission electron microscope (STEM). These are STEM photographs of the complex A.
FIG. 9 is a diagram showing a result of observing an example of the complex 1 (complex B, λmax = 729 nm) with a scanning transmission electron microscope (STEM). These are STEM photographs of the complex A.

FIG. 10 is a diagram showing the measurement result of the photothermal conversion characteristics of the photothermal conversion molded body 2.
As a result of measuring the transmittance of each photothermal conversion molded body 2 in the wavelength region of 220 nm to 2500 nm, the results shown in FIG. 10 were obtained. A thermocouple was attached to the opposite side of the CSNF layer, composite A layer, and composite B layer of the PET base material of each photothermal conversion molded body 2 using a heat-resistant tape, and peaked at about 1200 nm while measuring the temperature. A near-infrared lamp having
As a result, it was found that the temperature of the photothermal conversion molded body 2 provided with the composite layer was remarkably increased as compared with the molded body provided with the CSNF layer. In particular, the temperature was highest in the photothermal conversion molded body 2 provided with the composite A layer having absorption in a region near the peak wavelength of the near infrared lamp.
As described above, it was found that by providing the composite layer on the base material, the temperature of the PET base material was remarkably increased, and the remarkable photothermal conversion characteristics of the composite body 1 were shown.

[Effect of this embodiment]
Since the photothermal conversion molded body 2 according to the present embodiment includes the composite 1 having absorption in a specific wavelength region, it may have a minimum wavelength (λmax) in which the transmittance is minimum in a wavelength region of 400 nm to 2500 nm. preferable. In particular, when λmax is in the near infrared region of 700 nm or more and 2500 nm or less, the composite 1 exhibits a remarkable photothermal conversion characteristic, and a photothermal conversion molded body 2 having high visible light transmittance can be obtained.

  The photothermal conversion characteristic of the composite 1 can obtain, for example, the drying efficiency, the acceleration of thermal curing (crosslinking), or the acceleration effect of the UV curing reaction when forming a sheet-like molded body.

  As a result of the inventors providing a layer containing micronized cellulose on a PET substrate, and heating and drying and thermosetting to produce a sheet-like molded product, the high-temperature region of the sheet-like molded product was obtained by the effect of the micronized cellulose It has been found that the linear expansion coefficient in can be reduced. However, when the thickness of the sheet-like molded body is increased, a sufficient effect of lowering the linear expansion coefficient cannot be seen due to insufficient drying or curing on the substrate side. On the other hand, in the case of providing a layer containing the composite 1 in which fine cellulose and metal fine particles are combined, in the heat drying by irradiation with an infrared lamp (far infrared, middle infrared, near infrared) under the condition that the film thickness is thick It is easily heated and the linear expansion coefficient is further reduced. Further, by including the composite 1, the heating effect by the infrared lamp is enhanced, and it is possible to efficiently dry and cure the sheet, and the produced sheet-like molded product is imparted with photothermal conversion characteristics, and the photothermal conversion molded product 2. It can be used for various purposes.

Moreover, as described in Patent Document 5, when infrared rays (IR) are irradiated before UV light curing, the initiator is activated and the curing efficiency is increased. Furthermore, effects such as an improvement in the smoothness and flexibility of the coating film and a reduction in the viscosity of the coating liquid can be obtained. Irradiation after UV photocuring reduces stress and reduces curl. In cationic curing systems, acceleration of curing speed improves productivity and stabilizes curing. Removal of polymerization initiator removes decomposition odor. It becomes possible to reduce.
By including the composite 1, not only the effect of infrared irradiation, but also the photothermal conversion characteristics of the composite 1, the temperature of the coating film increases, the reactivity is improved, the crosslinking density is improved, and the scratch resistance is improved. improves.

Moreover, the strength of the photothermal conversion molded body 2 is improved by the effect of the composite 1 in the photothermal conversion molded body 2. The photothermal conversion molded body 2 preferably has a maximum strength of 50 N / mm ² or more and a breaking elongation of 10% or more.
The maximum strength and elongation at break are not particularly limited, but can be measured by, for example, the following method. The photothermal conversion molded body 2 is cut into a 15 mm width strip, and a small tabletop testing machine EZ-LX (manufactured by Shimadzu Corporation) is used, with a load cell of 1.000 N and a tensile speed of 5 mm / min. The tensile strength (N / mm ² ) and elongation at break (%) can be measured by detecting the elongation and strength in the long side direction while chucking both ends. The photothermal conversion molded body 2 is conditioned in a constant temperature and humidity chamber at 23 ° C. and 47 to 50% RH at least one day before the measurement, and the measurement is also performed in the same environment.

Furthermore, the photothermal conversion molded body 2 has a reduced linear expansion coefficient and increased dimensional stability. The linear expansion coefficient of the photothermal conversion molded body 2 is preferably 100 × 10 ⁻⁵ / K or less, more preferably 50 × 10 ⁻⁵ / K or less. When the linear expansion coefficient is within this range, the dimensional stability becomes high.
The linear expansion coefficient is not particularly limited, but can be measured by the following method. The photothermal conversion molded body 2 is cut into a strip of 4 mm in length of 15 mm, and the elongation in the long side direction when heated at 5 ° C./min from 15 to 180 ° C. while chucking both ends with a tension of 50 mN, The linear expansion coefficient is calculated from the sample elongation from 140 ° C. to 160 ° C., which is Tg or higher, using a mechanical device TMA / SS-6000 (manufactured by Seiko Instruments).

Although not particularly limited, the reaction rate of the crosslinking reaction can be measured with a Fourier transform infrared spectrophotometer (FT-IR). For example, using FT / IR-6300 (JASCO), the substrate side of the light-to-heat conversion layer, for a substrate opposite the scope of 400～4000Cm ^-1 by ATR respectively, resolution ^{4 cm -1,} number of integration 160 times Measure with In the case of an acrylic resin, the peak at 810 cm ⁻¹ (= C—H out-of-plane deformation angle; A) derived from a double bond is normalized by the peak at 1730 cm ⁻¹ (C═O stretching; B), and crosslinked. It can be used as an index of reaction reactivity. It can be judged that the lower the A / B peak intensity ratio is, the more the double bond is consumed and the cross-linking reaction proceeds.

[Use of Composite 1, Photothermal Conversion Molded Body 2, and Photothermal Conversion Composition]
Next, the use of the remarkable effect of the composite 1 will be described in detail.

The composite 1 efficiently absorbs light and emits it as thermal energy by LSPR that strongly absorbs light in a specific wavelength region as collective vibration of free electrons. As a result, heat diffuses into the medium around the composite 1. Since the composite 1 exhibits excellent light-to-heat conversion characteristics, the amount used can be reduced, and even when the amount used is reduced, the composite 1 has both high visible light transmittance and light-heat conversion characteristics. Furthermore, since the composite 1 has high stability and safety and does not select the type of resin when it is contained in the resin, it can be used in contact with the skin or in vivo.
On the other hand, near-infrared absorbing materials of organic compounds may be colored, have low durability, and may be decomposed by resins and additives. Moreover, the near-infrared absorbing material of a metal oxide may be colored by being reduced. Moreover, metal vapor deposition films, such as titanium, chromium, and nickel, have a metallic luster and visibility is inferior.

The composite 1 can directly use thermal energy by utilizing its photothermal conversion characteristics.
Examples of a method of directly using thermal energy include use as a material for photothermal treatment and a textile product.
Further, the composite 1 can be used for enhancing the functionality of the photothermal conversion molded body 2.
Further, by combining the composite 1 with a heat-responsive material, for example, as an optical recording material, a photosensitive material, a photothermal therapeutic material, a near-infrared light-responsive self-healing material, a laser irradiation peeling material, and a cell culture substrate Can be used.

The complex 1 can also be placed in the body in contact with the skin. For example, since the complex 1 generates heat in the skin or in vivo due to electromagnetic radiation from outside the body, the complex is accumulated in a malignant tumor site such as cancer in the skin or in vivo, and is killed by heat to perform photothermal treatment. Available to:
Further, by using the composite 1 for a textile product, warm clothes can be provided even in a cold season.

The composite 1 is irradiated with a lamp such as an infrared ray due to its photothermal conversion characteristics, whereby the coating film is heated and dried, that is, the solvent is removed and the photocuring material or thermosetting material is cured and photocured. It was suggested that it promotes and exhibits the effect of improving the strength and dimensional stability of the photothermal conversion molded body 2.
Usually, when a photothermal conversion composition 2 is used to produce a thick photothermal conversion molded body 2, the method of heating and drying the coating film with hot air tends to dry the surface side of the coating film. Is difficult to dry. On the other hand, if the heating is performed by irradiation with a lamp such as infrared rays, the photothermal conversion molded body 2 can be uniformly dried. At this time, drying by lamp irradiation, that is, solvent removal, thermal curing, and photocuring are promoted by the photothermal conversion characteristics of the composite 1.
By combining the composite 1 with a resin, in addition to the photothermal conversion characteristics of the composite 1, the effect of the micronized cellulose 12 bonded to the composite 1 allows the mechanical characteristics and the photothermal conversion molded body 2 to be formed at a high temperature. Dimensional stability that prevents expansion and contraction can be improved.
Furthermore, the composite 1 contained in the photothermal conversion molded body 2 according to the present embodiment can be concentrated by centrifuging at a low centrifugal acceleration, and is easy to concentrate compared to the refined cellulose 12 alone. Since the composite-containing material can be obtained at a concentration, the photothermal conversion molded body 2 having high strength and high dimensional stability can be obtained by removing the solvent with high productivity.

The composite 1 can be used to develop photoresponsiveness in combination with a thermoresponsive material, such as an optical recording material, a photosensitive material, a photothermal therapeutic material, a near-infrared light responsive self-repair. It can be used as a material, a laser irradiation peeling material, and a cell culture substrate. A thermoresponsive material is a material that changes physically and chemically by heat. Although not particularly limited, the physical change and the chemical change are a phase transition, a change in crystallinity, a change in the phase structure of a liquid crystal material, a change in a three-dimensional structure, decomposition or condensation due to heat, and the like.
Examples of the thermoresponsive material include poly (N-isopropylacrylamide) that causes swelling and shrinkage depending on temperature, a polymer that causes swelling / shrinkage, dispersion / aggregation, and sol-gel transition depending on temperature, water that is vaporized by heating, and the like. Examples thereof include a solvent, a crosslinking agent that causes a crosslinking reaction by heat, and a protein whose steric structure changes by heat.
Although not particularly limited, it can be used repeatedly by using a heat-responsive material that reversibly changes depending on the temperature.

Further, the photothermal conversion characteristics of the composite 1 can provide a near-infrared response and self-healing material that causes gel-sol change upon irradiation with near-infrared rays.
In the process of manufacturing a flexible display, a laser beam is irradiated by using the composite 1 in a sacrificial layer provided between a glass substrate and a heat-resistant plastic substrate for forming an electronic element or the like. Thermal deformation, thermal decomposition, peeling, etc. are possible.
By applying the composite 1 to a scaffold for cell culture, the scaffold material can be induced to be denatured by heat generated by laser irradiation, and the cultured cells can be detached without damage.

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

<Example 1>
(1-1 Preparation of sample)
(1-1-1 Production of Fine Cellulose 12)
The reagents and materials used for producing the fine cellulose 12 are shown below.
Cellulose: Bleached Kraft Pulp (Fletcher Challenge Canada “MACHENZIE”)
TEMPO: Commercial product (Tokyo Chemical Industry Co., Ltd., 98%)
Sodium hypochlorite: Commercial product (Wako Pure Chemical Industries, CL: 5%)
Sodium bromide: Commercial product (Wako Pure Chemical Industries, Ltd.)

70 g of softwood kraft pulp was suspended in 3500 g of distilled water to prepare a suspension.
To this suspension was added a solution prepared by dissolving 0.7 g of TEMPO and 7 g of sodium bromide in 350 g of distilled water, and cooled to 20 ° C.
To this solution, 450 g of an aqueous sodium hypochlorite solution having a concentration of 2 mol / L and a density of 1.15 g / mL was added dropwise to start an oxidation reaction. The temperature in the system during the reaction was always kept at 40 ° C. Further, the pH in the system was lowered during the reaction, but the pH was kept at 10 by successively adding a 0.5N aqueous sodium hydroxide solution.
When sodium hydroxide reached 3.0 mmol / g based on the mass of cellulose, an excessive amount of ethanol was added to stop the reaction.
Then, after filtering the mixture after reaction with a glass filter, the cellulose oxide was obtained by repeating the water washing and filtration by sufficient quantity of water.

1 g of oxidized cellulose obtained by TEMPO oxidation was dispersed in 99 g of distilled water.
And the refinement | purification process was performed to the dispersion liquid containing an oxidized cellulose using the high pressure homogenizer, and the refinement | purification cellulose (CSNF) aqueous dispersion liquid whose content of refinement | purification cellulose is 1 mass% was obtained.

(1-1-2 Production of Complex 1)
Subsequently, 500 mg of silver nitrate was dissolved in 100 mL of distilled water to prepare an aqueous silver nitrate solution.
Sodium borohydride 500mg was dissolved in distilled water 100mL, and sodium borohydride aqueous solution was prepared.
1 L of the above-mentioned fine cellulose aqueous dispersion was put in a container, and 10 g of an aqueous silver nitrate solution was added while stirring with a stirring blade to prepare a dispersion containing fine cellulose and silver nitrate. Subsequently, a sodium borohydride aqueous solution was added to the dispersion containing finely divided cellulose and silver nitrate and reacted to produce a composite dispersion. The complex 1 in the obtained complex dispersion is designated as complex A.

(1-1-3 Recovery of complex-containing material)
The complex A dispersion was diluted in a 1 L centrifuge tube, centrifuged at 10,000 × g (g is gravitational acceleration), and the sedimented complex was recovered. The solid content concentration was 10% by mass, A composite A-containing material having a silver concentration of 0.4% by mass was obtained.

(1-1-4 Production of Photothermal Conversion Composition and Photothermal Conversion Molded Body 2)
(1-1-4-1 Preparation of photothermal conversion composition)
PVA (Kuraray PVA-117, average polymerization degree 1,700, saponification degree 99.0 mol%) and methyl vinyl ether maleic anhydride copolymer (International Specialty Products GANTREZ AN119, average molecular weight 130,000 as a crosslinking agent) ) Was dissolved in hot water. PVA, a crosslinking agent, and the composite A were mixed so that the solid content weight ratio was 77:13:10 in this order to obtain a composition having a solid content concentration of 15% by mass. In addition, the solid content rate of the silver in a composition was 0.05 mass%.

(1-1-4-2 Production of Photothermal Conversion Molded Body 2)
The prepared solution was applied to a PET base material (Lumirror T60-75 μm: Toray) with an applicator and dried for 5 minutes with a near infrared dryer SIR-760 (manufactured by Toko) (lamp peak about 1200 nm). By peeling the PET substrate, a 40 μm thick photothermal conversion molded body 2 was produced.

(1-2 procedure)
About the obtained oxidized cellulose and refined cellulose, the measurement and calculation of the amount of carboxy groups, crystallinity, number average axis diameter of major axis, light transmittance and rheology were performed as follows.

(1-2-1 Measurement of carboxy group amount)
For the oxidized cellulose before the dispersion treatment, the amount of carboxy group was calculated by the following method.
0.2 g of dry weight equivalent of oxidized cellulose was taken in a beaker, and 80 mL of ion-exchanged water was added.
Thereto was added 5 mL of 0.01 mol / L sodium chloride aqueous solution, and 0.1 mol / L hydrochloric acid was added while stirring to adjust the whole to pH 2.8.
Then, using an automatic titration apparatus (trade name: AUT-701, manufactured by Toa DKK Co., Ltd.), a 0.1 mol / L sodium hydroxide aqueous solution was injected at 0.05 mL / 30 seconds, and the conductivity every 30 seconds was measured. The pH value was measured and the measurement was continued until pH 11.
From the obtained conductivity curve, the titration amount of sodium hydroxide was determined, and the content of carboxy group was calculated.

(1-2-2 Calculation of crystallinity)
The crystallinity of TEMPO oxidized cellulose was calculated.
For TEMPO-oxidized cellulose, using a sample horizontal multi-purpose X-ray diffractometer (trade name: Ultimate III, manufactured by Rigaku), X-ray output: (40 kv, 40 mA) under the condition of 5 ° ≦ 2θ ≦ 35 ° The line diffraction pattern was measured. Since the obtained X-ray diffraction pattern is derived from the cellulose I-type crystal structure, the crystallinity of TEMPO-oxidized cellulose was calculated by the following method using the following formula (2).
Crystallinity (%) = [(I22.6-I18.5) /I22.6] × 100 (2)
However, I22.6 is the diffraction intensity of the lattice plane (002 plane) (diffraction angle 2θ = 22.6 °) in X-ray diffraction, and I18.5 is the diffraction of the amorphous portion (diffraction angle 2θ = 18.5 °). Indicates strength.

(1-2-3 Calculation of number average axial diameter of major axis of fine cellulose)
The number average axial diameter of the major axis of the refined cellulose was calculated using an atomic force microscope.
First, after diluting the micronized cellulose aqueous dispersion to 0.001%, it was cast on a mica plate by 20 μL and air-dried.
After drying, the shape of the refined cellulose was observed in the DFM mode using an atomic force microscope (trade name: AFM5400L, manufactured by Hitachi High-Technologies Corporation).
The number average axial diameter of the major axes of the fine cellulose was determined by measuring the major axis diameter (maximum diameter) of 100 fibers from an image observed with an atomic force microscope, and obtaining the average value.

(1-2-4 Measurement of light transmittance of finely divided cellulose aqueous dispersion)
The light transmittance was measured for the finely divided cellulose aqueous dispersion.
One of the quartz sample cells is filled with water as a reference, and the other is filled with a finely divided cellulose aqueous dispersion so that bubbles are not mixed. It was measured with a meter (trade name: NRS-1000, manufactured by JASCO Corporation).

(1-2-5 Rheological measurement)
The rheology of a dispersion of 0.5% by mass of fine cellulose was measured with a rheometer (trade name: AR2000ex, manufactured by TA Instruments Inc.) using a cone plate with an inclination angle of 1 °.
The temperature of the measurement part was adjusted to 25 ° C., and the shear viscosity was continuously measured at a shear rate of 0.01 s ⁻¹ to 1000 s ⁻¹ . Table 1 shows the shear viscosity when the shear rate is 1 s ⁻¹ and 100 s ⁻¹ .

(1-3 results)
The obtained evaluation results are shown in Table 1, FIG. 11 and FIG. FIG. 11 is a graph showing the results of measuring the transmittance of the finely divided cellulose aqueous dispersion of Example 1. 12 is a graph showing the evaluation results of the viscosity characteristics of the finely divided cellulose aqueous dispersion of Example 1. FIG.
From the results of Table 1, FIG. 11 and FIG. 12, it was found that in Example 1, high crystallinity, high transmittance in the visible light region, and low viscosity refined cellulose could be produced.

  Next, a total of 14 types of samples of the resin molded body produced in Example 1, 7 types of additional examples (Examples 2 to 8) and 6 types of comparative examples (Comparative Examples 1 to 6) were combined. A sample of a resin molded body was prepared. After describing 14 types of samples, the results of experiments performed on each sample will be described. Table 2 shows the conditions for producing a sample of the resin molded body 1.

(2-1 Sample preparation)
<Example 2>
A photothermal conversion molded body 2 was produced under the same conditions as in Example 1 except that the solid content weight ratio of PVA, composite, and crosslinking agent was 82: 13: 5 in this order.

<Example 3>
A photothermal conversion molded body 2 was produced under the same conditions as in Example 1 except that an isobutylene maleic anhydride copolymer (Isoban 110 manufactured by Kuraray Co., Ltd., average molecular weight 170,000) was used as a crosslinking agent.

<Example 4>
A photothermal conversion molded body 2 was produced under the same conditions as in Example 1 except that PVA (PVA-105 manufactured by Kuraray Co., Ltd., average polymerization degree 500, saponification degree 99.0 mol%) was used.

<Example 5>
In the composite preparation step, a photothermal conversion molded body 2 was prepared under the same conditions as in Example 1 except that the composite B-containing material prepared by adding 20.0 g of the silver nitrate aqueous solution was used.

<Example 6>
In the composite preparation step, a photothermal conversion molded body 2 was prepared under the same conditions as in Example 1 except that the composite C-containing material prepared by adding 30.0 g of the silver nitrate aqueous solution was used.

<Example 7>
A photothermal conversion molded body 2 was produced in the same manner as in Example 1 except that the solid content ratio of the urethane resin dispersion HW171 (manufactured by DIC) and the composite A was 90:10 in this order.

<Example 8>
The composition was the same as in Example 1 except that the solid content ratio of acrylamide HEAA (manufactured by KJ Chemical), photopolymerization initiator Irgacure 2959 (manufactured by BASF), and composite A in this order was 89: 1: 10. Produced. In the same manner as in Example 1, the PET substrate was coated using an applicator, the solvent was removed, and then IR irradiation and 300 mJ / cm ² ultraviolet irradiation were performed using an ultraviolet irradiation conveyor device (made by Heraeus) with an infrared heater. Thus, a photothermal conversion molded body 2 was produced.

<Comparative Example 1>
A molded body was produced under the same conditions as in Example 1 except that the composite A was not added and the solid content weight ratio of PVA117, AN119, and CSNF was changed to 77:13:10 in this order.

<Comparative Example 2>
A molded body was produced under the same conditions as in Example 1 except that the composite A was not added and the solid content weight ratio of PVA117 and AN119 was changed to 86:14 in this order.

<Comparative Example 3>
A molded body was produced in the same manner as in Example 7 except that the composite A was not added and the solid content ratio of HW171 and CSNF was 90:10 in this order.

<Comparative example 4>
A molded body was produced in the same manner as in Example 7 except that the composite A was not added and only the composition of HW171 was obtained.

<Comparative Example 5>
A molded body was prepared in the same manner as in Example 8 except that the composite A was not added and the composition had a solids weight ratio of acrylamide HEAA, photopolymerization initiator Irgacure 2959, and CSNF in this order of 89: 1: 10. .

<Comparative Example 6>
A molded body was produced in the same manner as in Example 8 except that the composite A was not added and the composition was a solid weight ratio of acrylamide HEAA and a photopolymerization initiator Irgacure 2959 of 99: 1 in this order.

(2-2 Procedure)
Measurement and calculation of the amount of carboxy groups, the degree of crystallinity, the number average axis diameter of the major axis, the light transmittance and the rheology of the photothermal conversion molded body 2 and the molded body produced under the conditions shown in Table 2 are as follows. Went to.

(2-2-1 Measurement of λmax of complex)
The light transmittance of the inclusions of the composite A to the composite C in Examples 1 to 8 was measured.
A sample or reference was placed in a quartz sample cell, and the light transmittance from a wavelength of 220 nm to 1300 nm at an optical path length of 1 cm was measured with a spectrophotometer UV-3600 (manufactured by Shimadzu Corporation). The complex-containing material was appropriately diluted with water and measured in a quartz cell so that bubbles were not mixed. From the obtained light transmittance, the wavelength at which the light transmittance was minimized was defined as λmax (nm) of the dispersion.

(2-2-2 Observation of product)
The contents of composite A to composite C in Examples 1 to 8 were appropriately diluted, cast on a copper grid with a support film and air-dried, and then scanned with an electron microscope (trade name: S-4800, Hitachi) The composite A to the composite C of Example 1 to Example 8 were observed in the STEM mode.

(2-2-2-1 Calculation of average particle diameter)
The inclusions of composite A to composite C in Examples 1 to 8 were cast on a copper grid with a support film for transmission electron microscope observation and air-dried, and then observed with a scanning transmission electron microscope. The equivalent circle particle diameter is calculated as the particle diameter in the planar direction (particle diameter d) from the area when the flat metal particles in the scanning transmission electron microscope image are approximated by a circle. The particle diameter d of 100 particles was measured, and the average value was determined as the average particle diameter.

(2-2-2-2 Average aspect ratio calculation method)
The average aspect ratio of the composite A to the composite C in Example 1 to Example 8 was a value obtained by dividing the average particle diameter obtained as described above by the average thickness. The dispersion containing the composite is cast on a polyethylene terephthalate (PET) film, air-dried, fixed with an embedding resin, cut in the cross-sectional direction with a microtome, and observed with a transmission electron microscope. The transmission electron microscope image of the flat metal fine particle observed from the above was obtained. The thickness of the flat metal fine particles in this transmission electron microscope is calculated as the thickness h perpendicular to the plane direction, the thickness h perpendicular to the plane direction of 100 particles is measured, and the average value is obtained as the average thickness. It was.
The average value (average particle diameter) of the particle diameter d in the plane direction with respect to the average value (average thickness) of the thickness h of the flat metal fine particles is the average aspect ratio of the flat metal fine particles (average value of d / average value of h). Calculated as

(2-2-3 Film temperature measurement)
The photothermal conversion molded body 2 was cut out to 50 mm × 50 mm, and the thermocouple was attached to the side where the substrate 23 was peeled off using a heat resistant tape. The temperature of the film (from which the substrate 23 of the photothermal conversion molded body 2 has been peeled off) 30 seconds after irradiation with a near infrared lamp SIR-760 (manufactured by Toko) having a peak at about 1200 nm and the irradiation of the lamp is started. Was measured. Only in Example 1 (2), the base material 23 of the photothermal conversion molded body 2 created in Example 1 was not peeled off, and a thermocouple was attached to the base material 23 to measure the temperature of the base material 23.

(2-2-4 Tensile properties)
The obtained photothermal conversion molded body 2 was cut into a strip shape having a width of 15 mm, and an evaluation part of 50 mm was obtained using a small desktop tester EZ-LX (manufactured by Shimadzu Corporation) under the conditions of a load cell of 1.000 N and a tensile speed of 5 mm / min. The elongation and strength in the long side direction were detected while chucking both ends with an interval of λ, and the maximum strength (N / mm ² ) and elongation at break (%) were measured. The photothermal conversion molded body 2 was conditioned in a constant temperature and humidity chamber at 23 ° C. and 47 to 50% RH one day or more before the measurement, and the measurement was performed in the same environment.

(2-2-5 linear expansion coefficient)
The molded body I was cut into a strip shape of 15 mm length and 4 mm width, and the elongation in the long side direction when heated at 5 ° C./min from 15 to 180 ° C. while chucking both ends with a tension of 50 mN It measured using apparatus TMA / SS-6000 (made by Seiko Instruments), and the linear expansion coefficient was computed from the linear expansion coefficient of 20 to 40 degreeC, and the sample elongation of 140 to 160 degreeC more than Tg.

(2-2-6 Line light transmittance measurement)
The reference is measured in the sky, and the light transmittance of the photothermal conversion molded body 2 is measured with a spectrophotometer UV-3600 (manufactured by Shimadzu Corporation) from a wavelength of 220 nm to 2500 nm, and the transmittance values at a wavelength of 660 nm and a wavelength of 1200 nm. Got. From the obtained light transmittance, the wavelength at which the light transmittance was minimized was defined as λmax (nm) of the photothermal conversion molded body 2.

(2-2-7 Scratch resistance test)
In the steel wool test, COLOR-RASNESS RUBING TES (manufactured by Tester Sangyo Co., Ltd.) and Bonster # 0000 were used and rubbed 10 times with a load of 50 Hz and 200 g, and scratches were observed. If the number of scratches is 5 or less, “◯” is indicated. If the number of scratches is 6 or more and 10 or less, “Δ” is indicated. If the number of scratches is 11 or more, “X” is indicated.

(2-2-8 pencil hardness test)
Using a pencil scratch hardness tester (manufactured by Tester Sangyo), a scratch test was performed 5 times using a H pencil with a load of 500 g. When there were 5 or more and 4 or less, “△”, and when there were 5 scratches, “×”.

(2-3 results)
Table 3 shows λmax and average particle values for the complex A (FIG. 8), the complex B (FIG. 9), and the complex C (FIG. 13) used in Examples 1 to 4 and Examples 7 to 8. The measurement results of diameter, average thickness, and average aspect ratio are shown.
Table 4 shows the results of producing the photothermal conversion molded body 2 under the conditions described in Table 3 and evaluating the light transmittance, photothermal conversion characteristics, mechanical characteristics, linear expansion coefficient, scratch resistance, and pencil hardness.
In Comparative Examples 1 to 6, the film temperature was about 100 ° C., whereas in Examples 1 to 8, the film temperature was high and had high photothermal conversion characteristics. There was found. In particular, when the composite A having absorption near 1200 nm which is the peak of the lamp was used, remarkable photothermal conversion characteristics were confirmed. In Examples 1 to 8, the scratch resistance and pencil hardness were good, and it is considered that the physical properties of the film were improved by the photothermal conversion characteristics of the composite. In Example 1 (2), it was confirmed that the temperature of the base material also rose remarkably.
In addition, Example 1 is compared to Comparative Example 1 to Comparative Example 2, Example 7 is compared to Comparative Example 3 to Comparative Example 4, and Example 8 is compared to Comparative Example 5 to Comparative Example 6. The coefficient of linear expansion was low. It is considered that the drying and curing of the film was promoted by the photothermal conversion characteristics of the composite.

The photothermal conversion characteristic of the composite 1 can convert the irradiated light into thermal energy. By using the composite 1 for a textile product, it is possible to provide warm clothes even in the cold season having a heat generation effect using light energy.
It can also be used as a material for photothermal treatment. The complex 1 can also be placed in the body in contact with the skin. Since complex 1 generates heat by irradiation with electromagnetic waves from outside the body even in skin or in vivo, it can be used for photothermal treatment by accumulating complex 1 in malignant tumor sites such as cancer in the skin or in vivo and killing it by heat. it can.

The photothermal conversion characteristics of the composite body 1 can be used to improve the strength and dimensional stability of the photothermal conversion molded body 2 by promoting heat drying, thermal curing, and UV curing reaction by infrared lamp irradiation.
Usually, when the light-to-heat conversion molded body 2 having a large thickness is produced, only the surface side is dried by heating and drying with hot air, but the light-to-heat conversion molded body 2 is uniformly dried by heating by lamp irradiation such as infrared rays. It becomes possible. At this time, drying and thermosetting by lamp irradiation are promoted by the photothermal conversion characteristics of the composite 1.
Moreover, in photocuring such as UV light, the film is heated by irradiating a lamp such as infrared rays before or after photocuring, and curling can be suppressed by accelerating curing or stress relaxation. This promotes this effect.

Furthermore, the composite 1 and the thermoresponsive material can be combined to provide an optical recording material, a photosensitive material, a near-infrared light-responsive self-healing material, a laser irradiation peeling material, a cell culture substrate, and the like.
A composite 1 and a thermosensitive coloring material are mixed and coated on a base material, or a thermosensitive coloring material layer is provided on a base material, and a composite layer is provided thereon to form an optical recording medium by laser light irradiation. Can be used. When used as an optical recording medium by laser irradiation, the recording medium is not colored in a normal state, and a low output laser is used, and a sufficient recording density is obtained at a high recording speed.
Furthermore, when the organic compound is contained in the resin 21, there may be a problem in stability such as fading or decomposition depending on the type of the resin 21 or the like. The composite 1 has high stability and can be used repeatedly.
The photothermal conversion characteristics of the composite 1 can provide a near-infrared response and self-healing material that causes gel-sol change upon irradiation with near-infrared rays. In the process of manufacturing a flexible display, a laser beam is irradiated by using the composite 1 in a sacrificial layer between a glass substrate and a heat-resistant plastic substrate that forms an electronic element or the like, and the resin is efficiently thermally deformed. Thermal decomposition, peeling, etc. are possible. By applying the composite 1 to a scaffold for cell culture, the scaffold material can be induced to be denatured by heat generated by laser irradiation, and the cultured cells can be detached without damage.

DESCRIPTION OF SYMBOLS 1 ... Composite 11 ... Flat metal fine particle 12 ... Refined cellulose 12a ... Refined cellulose (part taken in the inside of a metal microparticle)
12b ... Refined cellulose (part exposed on metal fine particle surface)
d ... particle diameter h ... thickness 2 ... photothermal conversion molding 21 ... resin 23 ... base material

Claims (19)

  A photothermal conversion material, which is a composite of metal fine particles and at least one or more refined celluloses.   The photothermal conversion material according to claim 1, which is used for utilizing thermal energy.   The photothermal conversion material according to claim 1, wherein the photothermal conversion material is used in combination with a photocurable material or a thermosetting material, and used to promote thermal curing or photocuring of the photocurable material or the thermosetting material.   The photothermal conversion material according to claim 1, wherein the photothermal conversion material is used in combination with a resin and used for promoting solvent removal of a coating film for producing a photothermal conversion molded article.   The photothermal conversion material according to claim 1, wherein the photothermal conversion material is used in combination with a thermoresponsive material to develop photoresponsiveness. The metal fine particles are tabular metal fine particles;
At least a part or all of each of the finely divided cellulose is incorporated in the flat metal fine particles, and if there is a remainder, it is compounded so that the remainder is exposed on the surface of the flat metal fine particles,
The photothermal conversion material according to any one of claims 1 to 5. In the transmittance spectrum, in the wavelength region of 700 nm or more and 2500 nm or less, the transmittance has a minimum wavelength that minimizes the transmittance.
The photothermal conversion material according to any one of claims 1 to 6. The average value of the thickness h of the metal fine particles is in the range of 1 nm to 50 nm,
The average value of the particle diameter d is in the range of 2 nm to 1000 nm,
The average aspect ratio is 4.0 or more and 20.0 or less,
The photothermal conversion material according to any one of claims 1 to 7. The metal fine particles include at least one of gold, silver, and copper;
The photothermal conversion material according to any one of claims 1 to 8. The photothermal conversion material according to any one of claims 1 to 9, wherein at least a part of a surface of the composite is covered with a metal or a metal oxide. The micronized cellulose is fibrous and has a minor axis number average axis diameter of 1 nm to 50 nm and a major axis number average axis diameter of 0.1 μm to 10 μm.
The photothermal conversion material according to any one of claims 1 to 10. The fine cellulose has a minor axis number average axis diameter of 1 nm to 10 nm, a major axis number average axis diameter of 0.2 μm to 2 μm,
At least a portion of the glucopyranose is selectively oxidized at the C6-position OH group,
The photothermal conversion material according to any one of claims 1 to 11, wherein the amount of carboxy group is 0.1 mmol / g or more and 3.0 mmol / g or less.   The photothermal conversion composition containing the photothermal conversion material as described in any one of Claims 1-12. It is manufactured using the photothermal conversion composition according to claim 13,
Including a resin having at least one of a water-soluble polymer, an aqueous dispersion, an aqueous emulsion, and a photocurable resin,
Photothermal conversion molding. The resin has a crosslinked structure;
The resin is a polyvinyl alcohol polymer;
The crosslinked structure is formed by a crosslinking agent,
The crosslinking agent is a polymer having a molecular weight of 10,000 or more and less than 5,000,000,
The photothermal conversion molded object according to claim 14. The photothermal conversion molded article according to claim 14 or 15, wherein a content of the composite is 0.1% or more and 50% or less in terms of weight. The light-heat conversion molded article according to any one of claims 14 to 16, having a breaking strength of 50 N / mm ² or more and a breaking elongation of 10% or more. The linear expansion coefficient is 100 × 10 ⁻⁵ / K or less,
The photothermal conversion molded article according to any one of claims 14 to 17. The photothermal conversion molded article according to any one of claims 14 to 18, wherein the transmittance spectrum has a minimum wavelength at which the transmittance is minimum in a wavelength region of 700 nm to 2500 nm.