CN116762043A - Toner and image reading method - Google Patents

Toner and image reading method Download PDF

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Publication number
CN116762043A
CN116762043A CN202280012088.1A CN202280012088A CN116762043A CN 116762043 A CN116762043 A CN 116762043A CN 202280012088 A CN202280012088 A CN 202280012088A CN 116762043 A CN116762043 A CN 116762043A
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China
Prior art keywords
toner
gold
gold nanorods
image
range
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CN202280012088.1A
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Chinese (zh)
Inventor
吉正泰
山本毅
山火智
大桥良太
斋藤宏
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Canon Inc
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Canon Inc
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Priority claimed from JP2021151226A external-priority patent/JP2022117406A/en
Application filed by Canon Inc filed Critical Canon Inc
Priority claimed from PCT/JP2022/002904 external-priority patent/WO2022163709A1/en
Publication of CN116762043A publication Critical patent/CN116762043A/en
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Abstract

A toner comprising toner particles. The toner is characterized by containing gold nanorods, and is characterized in that, when an aspect ratio distribution of the gold nanorods contained in the toner is measured, an average value μ in the aspect ratio distribution is 6.0 to 13.0, and a standard deviation σ is 0.5 to 4.5.

Description

Toner and image reading method
Technical Field
The present disclosure relates to a toner and an image reading method.
Background
Recently, for the purpose of security enhancement such as copyright protection and forgery prevention, a "invisible printing" technique for embedding information as an invisible image in a printed material has attracted attention. In invisible printing, even when an invisible image is superimposed on a visible image, the invisible image is less likely to deteriorate the appearance of the visible image. Thus, the invisible image can be used in combination with the embedded information while maintaining the quality of the general printed material. Such invisible printing is expected to be applied to various fields including security fields.
Japanese patent application laid-open No.2007-219103 discusses a technique of forming an invisible image using a toner containing specific gold nanorods without impairing the quality of the visible image.
CITATION LIST
Patent literature
PTL 1: japanese patent laid-open No.2007-219103
Disclosure of Invention
As a result of studying the toner discussed in japanese patent application laid-open No.2007-219103, the present inventors have recognized that it is expected to further improve the invisibility of an image in the visible light region and the reading performance of an image in the near infrared region.
An aspect of the present disclosure is directed to providing a toner with which an invisible image having excellent invisibility in a visible light region and excellent reading performance in a near infrared region can be obtained.
Another aspect of the present disclosure is directed to an image reading method for reading an image formed using a toner according to the present disclosure.
According to one aspect of the present disclosure, the toner includes toner particles, wherein the toner includes gold nanorods, and wherein in the case of measuring an aspect ratio distribution of the gold nanorods included in the toner, an average μ in the aspect ratio distribution is in a range of 6.0 to 13.0, and a standard deviation σ in the aspect ratio distribution is in a range of 0.5 to 4.5.
According to another aspect of the present disclosure, there may be provided an image reading method including a process of reading an image formed with a toner according to the present disclosure using an apparatus equipped with a near infrared sensor.
According to one aspect of the present disclosure, a toner with which an invisible image having excellent invisibility in the visible light region and excellent reading performance in the near infrared region can be obtained can be provided.
According to another aspect of the present disclosure, there may be provided an image reading method including a process of reading an image formed with a toner according to the present disclosure using an apparatus equipped with a near infrared sensor.
Drawings
Fig. 1 is a schematic diagram showing an image observation state in image quality evaluation in the near infrared region.
FIG. 2 is the light absorption spectrum of PEDOT-PSS.
Detailed Description
Unless otherwise indicated, the descriptions of "xx above and yy below" and "xx to yy" representing numerical ranges are meant to include the numerical ranges including the lower and upper limits as endpoints. In addition, in the case where numerical ranges are described in sections, the upper limit and the lower limit of each numerical range may be arbitrarily combined.
The toner according to the present disclosure may preferably be a toner for invisible image formation.
< cause of the invention >
According to the technique discussed in japanese patent application laid-open No.2007-219103, image reading performance in the near infrared region can be reliably enhanced. On the other hand, the present inventors found that if the content of gold nanorods is increased to enhance image reading performance, the invisibility of the image is more likely to deteriorate. The inventors speculate that this is because the maximum absorptance in the near infrared region is not sufficiently large with respect to the maximum absorptance in the visible region in the light absorption spectrum of the fixed image. Therefore, the present inventors speculate that as the content of gold nanorods contained in the toner increases, not only the maximum absorbance in the near infrared region but also the maximum absorbance in the visible light region increases with the increase in the gold nanorod content, which results in deterioration of the invisibility of the image.
The invisible image forming toner is required to be capable of forming an image having excellent invisible property and excellent reading property. Accordingly, the present inventors have recognized that improvement is expected to be made to obtain an image in which the maximum absorption in the near infrared region is sufficiently large with respect to the maximum absorption in the visible region.
As a result of the study based on the above-described presumption, the present inventors found that a toner containing gold nanorods in which the average value of the aspect ratio was controlled to fall within the range of 6.0 to 13.0 and the standard deviation of the aspect ratio was controlled to fall within the range of 0.5 to 4.5 was effective for forming an image including the above-described features.
As a result, it was found that the average value and standard deviation of the aspect ratio of gold nanorods contained in the toner were respectively controlled to fall within the above ranges, so that the peak in the light absorption spectrum of the fixed image was sharper, and the maximum absorption rate in the near infrared region was made relatively larger. This makes it possible to easily obtain an image having excellent invisibility and excellent reading performance even in the case where the content of the gold nanorods in the toner is the same.
< gold nanorods >
The toner contains gold nanorods. In the present disclosure, gold nanorods are metallic nanorods consisting essentially of gold. The metal nanorod mainly composed of gold refers to a metal nanorod in which the content ratio of metallographic phase to mass of the metal nanorod is 80% or more.
The metal nanorods refer to a fine metal material formed of a metal material of noble metals such as gold and silver, and have a major axis diameter and a minor axis diameter in a Transmission Electron Microscope (TEM) image. Specifically, the metal nanorods in the TEM images were observed as a substantially rectangular shape. The metal nanorods typically have a short axis length of 1nm to 60nm and a long axis length of 20nm to 500nm. The value obtained by dividing the long axis length of the metal nanorods by the short axis length of the metal nanorods is called an aspect ratio. In the present disclosure, a metal nanorod having an aspect ratio of 1.5 or more is regarded as a gold nanorod. Gold nanorods respectively exhibit two characteristic plasmon absorption bands (bands corresponding to the excitation of the surface plasmon bands) due to the long axis of the rod and the short axis of the rod. For example, in the case of gold nanorods, an absorption band due to a short axis exists near 530nm, and an absorption band due to a long axis exists in the range of 650nm to 2000 nm.
The gold element and the metal element other than gold in the gold nanorods may have an alloy form obtained by compounding the elements at an atomic level, or may have a core-shell form in which the nanorods composed only of gold are coated with the metal element other than gold. The gold nanorods may be coated with, for example, an inert shell, such as silica or polystyrene. For example, depending on the intended use, the surface of the gold nanorods may be modified with appropriate molecules, such as surfactants, to disperse the gold nanorods into the medium.
< aspect ratio distribution >
The value obtained by dividing the long axis length of the metal nanorods by the short axis length of the metal nanorods is called an aspect ratio. The aspect ratio of the gold nanorods contained in the toner has a distribution, and the aspect ratio distribution is represented by an average value and a standard deviation in the distribution. The distribution may be a normal distribution, an irregular distribution or a multimodal distribution having a plurality of peaks.
The light absorption spectrum of gold nanorods varies in a complex manner with the change of the aspect ratio distribution. However, as a result of intensive studies, the present inventors found that, when measuring the aspect ratio distribution of gold nanorods contained in a toner, a toner containing gold nanorods in which the average value μ in the aspect ratio distribution is in the range of 6.0 to 13.0 and the standard deviation σ in the aspect ratio distribution is in the range of 0.5 to 4.5 was used, so that an invisible image having excellent invisibility in the visible light region and excellent reading performance in the near infrared region can be easily formed.
If the above average value μ falls within the range of 6.0 to 13.0, an image having a peak in the wavelength range of 1000 to 1600nm in the light absorption spectrum can be easily obtained. As a result, it was found that if the average value is less than 6.0, the peak position in the light absorption spectrum is more likely to be close to the visible light region, and therefore the invisibility of the image is insufficient. This seems to be because light having a wavelength in the visible light region can be absorbed more easily. As a result, it was also found that if the average value is greater than 13.0, the peak position in the light absorption spectrum may be too far on the long wavelength side, and the reading performance of an apparatus such as an InGaAs camera that reads wavelengths in the near infrared region is more likely to deteriorate.
In view of the above, the average value μ in the aspect ratio distribution is 6.0 or more, preferably 7.0 or more, and more preferably 8.0 or more. Further, the average value μmay be 13.0 or less, preferably 12.0 or less, and more preferably 11.0 or less. Specifically, for example, the average value μ is preferably in the range of 7.0 to 12.0, and more preferably in the range of 8.0 to 11.0.
The present inventors have also found that when the standard deviation σ in the aspect ratio distribution is 4.5 or less, the absorption wavelength in the near infrared region due to the gold nanorods is unlikely to change, and the maximum absorption in this region is relatively larger than the maximum absorption in the visible region.
An invisible image having excellent invisible property and excellent invisible image reading performance can be easily obtained. Therefore, the standard deviation σ may be 4.5 or less, preferably 3.5 or less, and more preferably 2.5 or less. Although the lower limit is not particularly limited, the standard deviation σ may be 0.5 or more.
Specifically, for example, the standard deviation σ may be preferably in the range of 0.5 to 3.5, and more preferably in the range of 0.5 to 2.5.
The average value μ and standard deviation σ can be controlled by adjusting the reaction conditions and refining conditions as described below.
Further, the average value of the long axis lengths of the gold nanorods contained in the toner particles is preferably less than or equal to 1/4 of the weight average particle diameter (D4) of the toner particles. The average value of the long axis length of the rod is set to be less than or equal to 1/4 of the weight average particle diameter of the toner particles, preventing the size of the gold nanorods from being extremely larger than the size of the toner particles. Further, the volume resistivity of the toner is less likely to deteriorate, so that appropriate charging characteristics of the toner can be easily obtained, and a high-quality invisible image can be easily obtained.
Further, the average value of the long axis lengths of the gold nanorods contained in the toner is preferably in the range of 50 to 110 nm.
The toner according to the present disclosure may be obtained by dispersing gold nanorods that satisfy the range of the average value μ and the range of the standard deviation σ according to the present disclosure into the toner, but alternatively, the toner may contain gold nanorods (hereinafter also referred to as "second gold nanorods") that do not satisfy the range of the average value μ and the range of the standard deviation σ according to the present disclosure without deviating from these values. Examples of the gold nanorods that may be contained in the toner may include gold nanorods whose average value of the aspect ratio distribution is in the range of 1.6 to 2.6 when the aspect ratio distribution is measured, and gold nanorods whose average value of the aspect ratio distribution is in the range of 2.0 to 2.2. When the light absorption spectrum of the gold nanorods was measured, the spectrum had peaks in the range of 580 to 650 nm.
In gold nanorods whose average value μ satisfies the range of 6.0 to 13.0 and whose standard deviation σ satisfies the range of 0.5 to 4.5, a large peak due to the long axis of each gold nanorod can be observed in the wavelength range of 1000 to 1600nm in the light absorption spectrum. On the other hand, a small peak due to the short axis of each gold nanorod can be observed around 530mm as a visible light region, and can appear slightly in red. Therefore, the addition of the above-described gold nanorods having peaks in the range of 580 to 650nm in the light absorption spectrum makes it possible to easily obtain an image having flatter optical absorption characteristics in the visible light region, i.e., an image having lower chromaticity and less likely to be visually observed.
< content ratio of gold nanorods >
The content ratio of the gold nanorods contained in the toner is preferably in the range of 0.005 to 0.200 mass%. If the content ratio of gold nanorods is 0.005 mass% or more, an invisible image having excellent reading performance in the near infrared region can be easily obtained. Therefore, the content ratio of the gold nanorods is preferably 0.005 mass% or more, and more preferably 0.010 mass% or more. If the content ratio of gold nanorods is 0.200 mass% or less, the volume resistivity of the toner is less likely to deteriorate, and a high-quality invisible image can be easily obtained. Therefore, the content ratio of the gold nanorods is preferably 0.200 mass% or less, and more preferably 0.100 mass% or less.
< gold nanoparticle >
Preferably, the toner does not contain gold nanoparticles, or contains gold nanoparticles at 30% or less relative to the number of gold nanorods contained in the toner. In the present disclosure, gold nanoparticles are nanomaterials composed mainly of gold, and are regarded as nanoparticles having an aspect ratio of less than 1.5 in TEM images. Gold nanoparticles can be produced during the preparation of gold nanorods. Depending on the particle size, gold nanoparticles exhibit light absorption in the visible region. For example, gold nanoparticles having a particle size of 20nm exhibit light absorption around 520 nm.
If the toner does not contain gold nanoparticles or contains gold nanoparticles at 30% by number or less relative to the number of gold nanorods, the light absorptivity in the visible light region corresponding to the absorption wavelength of the gold nanoparticles is small, and thus an image having excellent invisibility can be easily obtained. More preferably, the toner does not contain gold nanoparticles, or contains gold nanoparticles in a proportion of 15% or less. More preferably, the toner does not contain gold nanoparticles, or contains gold nanoparticles at a ratio of 10% or less. More preferably, the toner does not contain gold nanoparticles, or contains gold nanoparticles in a proportion of 5% or less.
The number ratio of gold nanoparticles can be controlled based on the reaction conditions and refining conditions as described below.
<PEDOT-PSS>
Toners according to the present disclosure may comprise poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonic acid) (PEDOT-PSS). In the present disclosure, poly (3, 4-ethylenedioxythiophene) is also known as PEDOT, and poly (styrenesulfonic acid) is also known as PSS. The PEDOT-PSS according to the present disclosure is considered to be a complex of PEDOT and PSS.
PEDOT-PSS will be described. When an electron acceptor (acceptor) or an electron donor (donor) is added to a conjugated polymer, a carrier (hole or electron) is generated in the main chain of the conjugated polymer, and a polymer complex having conductivity is formed. Such polymer composites are generally called conductive polymers. Typical examples of conjugated polymers include aliphatic conjugated polyacetylenes, aromatic conjugated poly (p-phenylene), heterocyclic conjugated polypyrroles, polythiophenes, and heteroatom conjugated polyanilines. Examples of acceptors include halogens and lewis acids. Examples of donors include alkali metals and alkaline earth metals.
The conductive polymer exhibits infrared absorption due to the plasma oscillation of carriers. In other words, it is considered that the infrared absorption property is exhibited when a polymer complex of a conjugated polymer and an electron acceptor or an electron donor is formed. Since the infrared absorption of the conductive polymer is proportional to the carrier density, the conductive polymer having higher conductivity exhibits higher infrared absorption.
In the PEDOT-PSS included in the toner according to the present disclosure, the PEDOT functions as a conjugated polymer, the PSS functions as a receptor, and the PEDOT and the PSS form a polymer complex, which exhibits high infrared absorption.
FIG. 2 shows the light absorption spectrum of PEDOT-PSS. Based on the plasma oscillation of carriers in the infrared region, PEDOT-PSS has a large light absorption band. Therefore, an image having excellent reading performance in the near infrared region can be easily obtained using the toner containing PEDOT-PSS.
In fig. 2, light absorption due to plasma oscillation of carriers reaches not only the infrared region but also the visible region of 500 to 800 nm. The light absorption reaching the visible light region makes a small peak existing around 530nm flatter due to the short axis satisfying each gold nanorod having the average value μ in the range of 6.0 to 13.0 and the standard deviation σ in the range of 0.5 to 4.5, and makes it possible to easily obtain an image having a lower chromaticity and less likely to be visually observed.
PEDOT-PSS can also be produced by, for example, carrying out the oxidative polymerization of 3, 4-ethylenedioxythiophene in the presence of PSS. Commercially available products (for example, denatron PT-300 (trade name) manufactured by Nagase ChemteX Corporation) can also be obtained and used.
< preparation of gold nanorods >
Examples of the method for producing gold nanorods include electrolytic methods (Y.Yuhoka, J.Phys.Chem, B,101, 6661 (1997)) and chemical synthesis methods (N.R.Janahoka, J.Phys.Chem.B,105, 4065 (2001)).
For example, a method of synthesizing gold nanorod particles by reducing gold ions in an aqueous solution containing an excessive amount of cetyltrimethylammonium bromide (CTAB) as a quaternary ammonium base can be used. For details of this method, see, for example, japanese patent application laid-open No.2006-118036, japanese patent application laid-open No.2006-169544, chem. Commun. (2003), pages 2376-2377. In this method, a solution containing seed particles is prepared by first adding a CTAB aqueous solution to an aqueous solution of chloroauric acid tetrahydrate (hydrogen tetrachloroaurate tetrahydrate), and further adding sodium borohydride to the aqueous solution. A solution obtained by mixing silver nitrate, chloroauric acid tetrahydrate, L-ascorbic acid, and CTAB was added to the solution and held for a certain period of time, or gradually added little by little, thereby promoting anisotropic growth of seed particles as cores and obtaining gold nanorods.
Further, in the case of growing seed particles, gold nanorods having a large aspect ratio can be obtained by adding benzyl dimethyl hexadecyl ammonium chloride. In addition, gold nanorods having a large aspect ratio can also be obtained by performing a reduction treatment using sodium borohydride as a strong reducing agent and then performing a reduction treatment using triethylamine as a weak reducing agent in the first stage.
Furthermore, gold nanorods can be refined as desired, and the aspect ratio distribution can be tuned and used. As the purification method, any known method can be used. For example, a density gradient ultracentrifugation separation method can be used. For details on this approach, see, for example, li.S, et al, nano Res.4,723-728 (2011). Specifically, first, mixed solutions of sucrose and CTAB at different concentrations were prepared, and these solutions were stacked in the centrifuge tube in order of concentration gradient. A sample of gold nanorods is superimposed on the solution, and then subjected to a centrifugation process, thereby separating the gold nanorods based on the concentration and size of the gold nanorods. The separation and refining process makes it possible to reduce the standard deviation σ and obtain gold nanorods with a narrower aspect ratio distribution.
< toner and toner particles >
The toner particles preferably contain a binder resin. The binder resin is not particularly limited. Specific examples of the binder resin may include styrene acrylic resins, polyester resins, and epoxy resins. These resins may be used alone or as a mixture. The binder resin may be a resin having a linear molecular structure, a resin having a branched shape, a crosslinked resin, or a mixture thereof.
< light absorptance in visible light region >
At a toner loading of 0.30mg/cm 2 In the spectral analysis of a fixed image formed using the toner according to the present disclosure, the maximum value of the light absorptance in the wavelength range of 400nm to 800nm is preferably 10% or less. The wavelength range is a wavelength region corresponding to the visible light region. If the light absorptivity is 10% or less, an image which is substantially not recognized with the naked eye and thus has excellent invisibility in the visible light region can be obtained.
< light transmittance in visible light region >
In terms of the invisibility of the image, the loading amount of the toner was 0.30mg/cm 2 In the spectral analysis of a fixed image formed using the toner according to the present disclosure, the maximum value of the light transmittance in the wavelength range of 400nm to 800nm is preferably 90% or more.
< light absorptance in near infrared region >
At a toner loading of 0.30mg/cm 2 Spectrum of a fixed image formed in the case of (a)In the analysis, the maximum value of the absorbance of light in the wavelength range of 900nm to 1800nm is preferably 5% or more. The wavelength range is a wavelength region corresponding to the near infrared region. If the light absorptivity is 5% or more, an invisible image can be clearly read using a near infrared camera such as an InGaAs camera. More preferably, the light absorptance is 10% or more.
If toner is used as the invisible toner in practice, a camera equipped with a sensor having sensitivity in the range of 900nm to 1800nm (InGaAs sensor or the like) may be used to visualize light absorption in the invisible region, for example.
By adjusting the aspect ratio distribution of the gold nanorods, the light absorptivity in the visible light region and the infrared region can be controlled.
< image reading method >
The method for reading an image formed using the toner according to the present disclosure is not particularly limited. An image formed using the toner according to the present disclosure is more likely to absorb wavelengths in the near infrared region, and thus it is desirable to employ an image reading method using an apparatus equipped with a near infrared sensor. More preferably, a device equipped with InGaAs sensors may be used. More preferably, an InGaAs camera may be used. An image reading method using light in a wavelength range of 900 to 2500nm, and more preferably in a wavelength range of 900 to 1800nm can be preferably employed.
< weight average particle diameter (D4) of toner particles >
The weight average particle diameter (D4) of the toner particles is preferably in the range of 4.0 μm to 9.0 μm, and more preferably in the range of 5.0 μm to 7.0 μm. The weight average particle diameter (D4) within this range is advantageous for the formation of high-definition images.
< method for producing toner >
The toner manufacturing method is not particularly limited. For example, the following toner manufacturing methods (1) to (3) may be used.
(1) Crushing method
In the case of manufacturing a toner by pulverization, metal nanorods including gold nanorods are first thoroughly mixed with a binder resin as a dispersion medium or another additive by a mixer such as a henschel mixer or a ball mill. The mixture is melted and kneaded using a thermal kneader such as a kneader or an extruder using thermal and mechanical shearing force and the resins are made compatible with each other. The melted and kneaded material is cooled and solidified, and then the solidified material is pulverized, and the pulverized material is classified, thereby obtaining toner particles having a desired particle diameter.
(2) Suspension polymerization process
In the suspension polymerization method, for example, a metal nanorod including a gold nanorod, a polymerizable monomer that can form a binder resin, and if necessary, a polymerization initiator, a crosslinking agent, a charge control agent, and other additives are uniformly dispersed, thereby obtaining a polymerizable monomer composition. Thereafter, the obtained polymerizable monomer composition is dispersed and granulated in a continuous layer (e.g., aqueous phase) containing a dispersion stabilizer using an appropriate mixer, and a polymerization reaction process is performed using a polymerization initiator, thereby obtaining toner particles having a desired particle diameter.
(3) Emulsion coalescence method
In the case of manufacturing a toner by emulsion coalescence, each material such as a metal nanorod including a gold nanorod, a binder resin, and other additives is first dispersed and mixed in an aqueous medium containing a dispersion stabilizer. The surfactant may be added to the aqueous medium. Thereafter, the toner particles are agglomerated by adding a flocculant to obtain a desired toner particle diameter. Thereafter, or simultaneously with the coalescing, the resin fine particles are fused. Further, shape control is performed using heat as needed, thereby forming toner particles. Thereafter, a filter cleaning process and a drying process are performed, thereby obtaining toner particles.
If desired, a series of toner manufacturing processes may include a process of dispersing metal nanorods in a binder resin.
As a method of dispersing the metal nanorods in the binder resin, for example, a method using a master batch during the toner manufacturing process may be used. Specifically, the metal nanorods are mixed with some binder resin so that the metal nanorods are contained at a high concentration, and a melting and kneading process is performed with a high shear force applied, thereby manufacturing a master batch in which the metal nanorods are finely dispersed. Thereafter, the master batch is melted and kneaded while being diluted with the remaining binder resin. As a melting and kneading apparatus suitable for producing the master batch, a kneader, a banbury mixer, a two-roll, or a three-roll mill, or the like can be used. These may be used alone or in combination. As the melting and kneading apparatus for dilution and kneading, a biaxial kneader or the like can be used.
The series of toner manufacturing processes may include a process of preventing aggregation of metal nanorods, as needed.
As a method of preventing aggregation of the metal nanorods in the toner manufacturing process, for example, a method of quenching the metal nanorods after the melting and kneading process may be used. For example, the melted and kneaded material spreads in a sheet shape on a water-cooled metal belt, so that the melted and kneaded material can be quenched. Rapid cooling prevents aggregation of the metal nanorods caused during cooling. As cooling apparatuses suitable for rapid cooling, for example, "NR twin-belt cooler for high viscosity (manufactured by Nippon Belting co., ltd.)," cooling and solidifying machine belt roller tablet press (manufactured by Nippon Coke & Engineering co., ltd.), "and" cooling and solidifying apparatus roller tablet press (manufactured by Katsuragi Industry co., ltd.), "can be used.
The process of dispersing the metal nanorods in the binder resin and the method of preventing aggregation of the metal nanorods may be used in combination.
< various additives >
The toner may contain one or more kinds of additives selected from the group consisting of wax, charge control agent, external additive, and the like as necessary. Further, the toner according to the present disclosure preferably does not contain any coloring component that can change the fixed image into a visible image.
< wax >
The wax is not particularly limited, but colorless or pale colored wax is preferably used. The following waxes may be used.
Hydrocarbon waxes, ester waxes, amide waxes, higher fatty alcohols, higher fatty acids, and the like can be used. One kind of wax may be used alone, or plural kinds of waxes may be used in combination.
< Charge control agent >
The charge control agent is not particularly limited, but a colorless or pale-colored charge control agent is preferably used. Examples of the charge control agent are described below.
Examples of the charge control agent include aromatic hydroxycarboxylic acids, metal compounds of aromatic hydroxycarboxylic acids, boron compounds, quaternary ammonium salts, calixarenes, resins containing sulfonic acid (salt) groups, and resins containing sulfonate ester groups. One kind of charge control agent may be used alone, or plural kinds of charge control agents may be used in combination.
< external additive >
The external additive is not particularly limited, but a colorless or pale-colored external additive is preferably used. The following external additives may be used.
Silica, alumina, titania, strontium titanate, silicon nitride, polytetrafluoroethylene, zinc stearate, and the like can be used. The surface of the external additive may be subjected to a hydrophobization treatment.
The average particle diameter of the primary particles of the external additive is preferably 1/10 or less of the weight average particle diameter (D4) of the toner particles.
< developer >
The toner may be used as a one-component developer, or may be used as a two-component developer by mixing the toner with a carrier. As the carrier, for example, metals such as iron, ferrite, and magnetite, an alloy of these metals with another metal such as aluminum or lead, and magnetic particles composed of a known material can be used. In addition, a coated carrier whose surface is coated with a coating agent such as a resin, a resin dispersion type carrier obtained by dispersing magnetic particles in a binder resin, or the like may also be used. The volume average particle diameter of the support is preferably in the range of 15 μm to 100 μm, and more preferably in the range of 25 μm to 80 μm.
< methods of measuring various kinds >
Various physical properties were measured as follows.
< method for measuring weight average particle diameter (D4) of toner particles >
The weight average particle diameter (D4) of the toner particles is calculated as follows.
As the measurement apparatus, a precision particle size distribution measurement apparatus "Coulter Counter Multisizer" (registered trademark, manufactured by Beckman Coulter, inc.) provided with a 100 μm mouth tube and employing resistance pulse sensing was used. The measurement conditions were set and the measurement data were analyzed using the accompanying proprietary software "Beckman Coulter Multisizer 3version 3.51" (manufactured by Beckman Coulter, inc.). Measurements were made with 25000 valid measurement channels.
As the aqueous electrolyte solution for measurement, an aqueous solution obtained by dissolving extra sodium chloride in ion-exchanged water at a concentration of about 1 mass%, for example, "ISOTON II" (manufactured by Beckman Coulter, inc. Can be used.
The above dedicated software is set up as follows before measurement and analysis.
On the "standard measurement method (SOM) change" interface of the above dedicated software, the total count value of the control mode was set to 50,000 particles, the number of measurements was set to 1, and the value obtained using "standard particle 10.0 μm" (manufactured by Beckman Coulter, inc.) was set to Kd value. The threshold and noise level are automatically set by pressing the "threshold/noise level measurement button". The current was set at 1600 μa, the gain was set at 2, and the electrolyte solution was set at ISOTON II, then "post-measurement flush port tube" was checked. On the interface of the above-described dedicated software "pulse-to-particle diameter conversion setting", the element pitch was set to logarithmic particle diameter, the number of particle diameter elements was set to 256, and the particle diameter range was set to a range of 2 μm to 60 μm.
Specific measurement methods are described below.
(1) About 200mL of the aqueous electrolyte solution was placed in a 250mL round bottom beaker made of glass dedicated to Multisizer 3. The beaker was set on a sample stand and the aqueous electrolyte solution in the beaker was stirred with a stirring bar in a counter-clockwise direction at 24 revolutions per second. Then, dirt and bubbles in the mouth tube are removed by the "flush mouth tube" function of the dedicated software.
(2) About 30mL of the aqueous electrolyte solution was placed in a 100mL flat bottom beaker made of glass. About 0.3mL of a dilution solution obtained by diluting "conteminon N" (a 10 mass% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, including a nonionic surfactant, an anionic surfactant, and an organic auxiliary agent manufactured by FUJIFILM Wako Pure Chemical Corporation) with ion-exchange water by about 3 times by mass was added thereto as a dispersant.
(3) An ultrasonic disperser "Ultrasonic Dispersion System Tetora" having an electrical output of 120W (manufactured by Nikkaki Bios co.ltd.) was prepared by introducing two oscillators having oscillation frequencies of 50kHz in a state where the phases of the respective oscillators were shifted by 180 degrees. About 3.3l of ion-exchanged water was placed in a water tank of an ultrasonic disperser, and about 2mL of Contaminon N was added to the water tank.
(4) The beaker in the step (2) is arranged in a beaker fixing hole of the ultrasonic disperser, and the ultrasonic disperser is activated. The height position of the beaker is adjusted so that the resonance state of the liquid level of the electrolyte aqueous solution in the beaker is maximized.
(5) In a state where the aqueous electrolyte solution was irradiated with ultrasonic waves, about 10mg of toner particles were gradually added little by little and dispersed in the aqueous electrolyte solution in the beaker described in section (4). Then, the ultrasonic dispersion treatment was continued for another 60 seconds. The temperature of the water in the water tank is suitably adjusted so as to be maintained in the temperature range of 10 to 40 ℃ at the time of ultrasonic dispersion.
(6) Part (5) of the aqueous electrolyte solution in which toner particles were dispersed was dropped by means of a pipette into the round-bottomed beaker described in part (1) placed on the sample holder, and the measured concentration was adjusted to about 5%. The measurement was performed until the number of measurement particles reached 50,000.
(7) The measurement data were analyzed using the above-described dedicated software attached to the apparatus, and the weight average particle diameter was calculated (D4). When the graph/volume% is set by dedicated software, the "average diameter" on the "analysis/volume statistics (arithmetic average)" interface corresponds to the weight average particle diameter (D4).
< method for quantifying the Metal content in Metal nanorod Dispersion >
The metal content in the metal nanorod dispersion can be quantified by an Inductively Coupled Plasma (ICP) emission spectrometry method based on Japanese Industrial Standard (JIS) K0116-2014. First, the metal nanorod dispersion was heated at 60 ℃ on a hot plate, and dried and hardened. Then, aqua regia was added to the resultant, and microwave-assisted acidolysis was performed using ETHOS PRO (manufactured by Milestone General k.k.) or the like. ICP emission spectroscopic analysis was performed on the liquid using a CIROS CCD (manufactured by spectra inc.) so that the metal content could be quantified.
< method for measuring aspect ratio distribution of gold nanorods contained in toner >
To measure the aspect ratio distribution of gold nanorods contained in the toner, the gold nanorods contained in the toner were first separated and collected.
First, a solvent that can dissolve the binder resin is used to dissolve the toner. Next, gold nanorods were precipitated by centrifugation, and the supernatant was separated. Centrifugation was again performed by adding new solvent, and the supernatant was separated. This operation was repeated several times for cleaning. Then, the solvent is finally dried and removed, so that the gold nanorods can be separated and collected from the toner. The collected gold nanorods are redispersed in a solvent such as Tetrahydrofuran (THF), thereby obtaining a measurement sample.
The measurement sample dispersed in the solvent was dropped onto a support film and dried, whereby TEM observation was performed with a transmission electron microscope "Technai F30 (manufactured by FEI Corporation)" or the like. The observed long axis length and short axis length of the gold nanorods are obtained by image processing software such as Photoshop, and the average value and standard deviation of the aspect ratio distribution of the gold nanorods and the average value of the long axis length can be obtained.
< method for measuring the number ratio of gold nanoparticles to gold nanorods contained in toner >
The ratio of the number of gold nanoparticles to the number of gold nanorods contained in the toner may be measured such that the number of gold nanoparticles and the number of gold nanorods are counted by TEM observation, and the ratio between the number of gold nanoparticles and the number of gold nanorods is calculated.
< method for measuring the content of gold nanorods contained in toner >
The content (mass%) of gold nanorods contained in the toner was quantified by fluorescent X-ray analysis. The measurement is based on JIS K0119-1969 as described in detail below.
As the measurement apparatus, a wavelength dispersion type fluorescent X-ray analysis apparatus "Axios" (manufactured by Malvern Panalytical ltd.) and accompanying dedicated software "SuperQ ver.4.0f" (manufactured by Malvern Panalytical ltd.) were used for measurement condition setting and measurement data analysis. Note that Rh was used as an anode of the X-ray tube, a vacuum atmosphere was set as a measurement atmosphere, a measurement diameter (collimator mask diameter) was 27mm, and a measurement time was 10 seconds. The light elements are measured using a Proportional Counter (PC) and the heavy elements are measured or detected using a Scintillation Counter (SC).
As a measurement sample, 4g of toner particles were placed in a dedicated aluminum ring for pressing, flattened and pressed for 60 seconds at a pressure of 20MPa using a tablet forming compressor "BRE-32" (manufactured by Maekawa Testing Machine mfg. co., ltd.) and formed into pellets having a thickness of 2mm and a diameter of 39 mm. The pellets thus obtained were used.
The measurement was performed under the above conditions, the element was discriminated based on the peak position of the obtained X-rays, and the count rate (unit: kcps) was measured as the number of X-ray photons per unit time. Then, the content of gold nanorods contained in the toner was calculated using a calibration curve created separately. In the case of creating the calibration curve, finely pulverized material of the styrene-based resin and a predetermined amount of gold nanorods were uniformly mixed with each other using a coffee grinder, and pellets produced in the same manner as described above were used as measurement samples.
Examples
The present disclosure will be described in more detail below with reference to examples. However, the present disclosure is not limited to these embodiments. The measurement results in the examples were obtained by the above-described measurement methods.
Preparation example of gold nanorod Dispersion A
First, a seed particle solution is prepared. Then, 500ml of an aqueous solution of 0.0005mol/L chloroauric acid tetrahydrate (chloroauric acid tetrahydrate) (Kishida Chemical co., ltd.) and 500ml of an aqueous solution of 0.2mol/L cetyltrimethylammonium bromide (Kishida Chemical co., ltd.) were mixed. Then, 60ml of 0.01mol/L sodium borohydride (Tokyo Chemical Industry co., ltd.) was added to the aqueous solution, thereby obtaining a seed particle solution (solution a).
Next, 10g of cetyltrimethylammonium bromide was dissolved in 500ml of 0.15mol/L aqueous benzyl dimethyl cetylammonium chloride (Tokyo Chemical Industry co., ltd.). Then, 20mL of a 0.004mol/L aqueous silver nitrate solution was added to the aqueous solution containing both surfactants. Furthermore, 500ml of a 0.001mol/L aqueous solution of chloroauric acid tetrahydrate was added to the aqueous solution, followed by further addition of 7ml of a 0.078mol/L L-aqueous solution of ascorbic acid (Kishida Chemical co., ltd.). This solution was used as solution B.
Next, 10g of cetyltrimethylammonium bromide was dissolved in 500ml of 0.15mol/L aqueous benzyl dimethyl cetylammonium chloride (Tokyo Chemical Industry co., ltd.). Then, 20mL of a 0.004mol/L aqueous silver nitrate solution was added to the aqueous solution containing both surfactants. To the aqueous solution was added 500mL of a 0.0005mol/L aqueous solution of chloroauric acid tetrahydrate, followed by further addition of 3.6mL of a 0.078mol/L L-aqueous solution of ascorbic acid (Kishida Chemical Co., ltd.). This solution was used as solution C.
Then, 1.2mL of the solution A was added dropwise to the solution B, and 2.0mL of the solution C was added at a rate of 1.0mL/20min, and seed particles as nuclei were anisotropically grown. After centrifugation at 10,000Xg for 5 minutes, the gold nanorods were redispersed in THF to obtain a content ratio of 0.02 mass%, and a gold nanorod dispersion (dispersion A) was obtained. Table 1 illustrates the physical properties of the gold nanorods contained in the dispersion a.
Preparation examples of gold nanorod Dispersion solutions B to J
Dispersions B to J were obtained by performing operations similar to those in the preparation example of dispersion a except that the amount of solution C was changed as shown in table 1 and the following refining process was performed in the preparation example of gold nanorod dispersion a.
(refining Process)
The gold nanorod dispersion obtained in 6mL was subjected to a centrifugal separation process at 10,000Xg for 5 minutes, and then the obtained pellet was resuspended in 0.05mL 0.01M CTAB aqueous solution to obtain a gold nanorod suspension. In addition, sucrose solutions were prepared by adding sucrose to 0.01M CTAB aqueous solutions at 10 mass%, 15 mass%, 20 mass% and 25 mass%, respectively. Then, 3mL of each solution containing sucrose was placed in a 15mL centrifuge tube (polyallomer) in the order of decreasing sucrose concentration, and finally the above gold nanorod suspensions were stacked. Then, a centrifugation process was performed at 25℃and 10750 Xg for 15 minutes using a high-speed cryocentrifuge "Avanti JXN-30". After the centrifugation process, the solution was separated into 300. Mu.L of fractions, and TEM images of the fractions containing gold nanorods were observed. Among these fractions, centrifugal separation process was performed at 10,000×g for 5 minutes for each fraction in which the average μ and standard deviation σ of aspect ratios calculated based on TEM images were desired values, and gold nanorods as precipitates were collected. Then, the collected gold nanorods were redispersed in THF to obtain a content ratio of 0.02 mass%.
< preparation example of gold nanorod Dispersion K >
[ preparation of seed particle solution ]
First, a seed particle solution (solution a) similar to the above was prepared.
Next, 5.0ml of 0.004mol/L silver nitrate (Kishida Chemical co., ltd.) aqueous solution was added to 500ml of 0.2mol/L cetyltrimethylammonium bromide aqueous solution in another container. Then, 500ml of a 0.001mol/L aqueous solution of chloroauric acid tetrahydrate was added to the aqueous solution, and 7ml of a 0.078mol/L L-aqueous solution of ascorbic acid (Kishida Chemical co., ltd.) was further added. This solution was used as solution B.
Then, 1.2mL of solution A was added dropwise to solution B. The temperature of the solution was maintained at 30℃for 20 minutes, and seed particles were anisotropically grown as nuclei, thereby obtaining a particle dispersion K1.
[ refining Process ]
Using the particle dispersion K1 obtained as described above, a dispersion K was prepared by performing an operation similar to the refining process in the production example of the dispersion a. Table 1 shows physical properties of gold nanorods (second gold nanorods) contained in the dispersion K. When the light absorption spectrum of the gold nanorods contained in the dispersion liquid K was measured, the peak wavelength of light absorption in the spectrum was 610nm.
TABLE 1
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Production example of saturated polyester 1 Dispersion
20.0 parts by mass of a saturated polyester 1 (polycondensate of ethylene oxide-modified bisphenol A and terephthalic acid, glass transition temperature 60 ℃, weight-average molecular weight 29000, and number-average molecular weight 6000)
80.0 parts by mass of THF
The above materials were thoroughly mixed to obtain a saturated polyester 1 dispersion.
Production example of toner 1
33.0 parts by mass of gold nanorod dispersion A
67.0 parts by mass of a saturated polyester 1 dispersion
The above materials were sufficiently stirred with a magnetic stirrer, and added dropwise to heptane (Kishida chemical co., ltd.) and reprecipitated. The precipitate was collected by suction and filtration, and a mixture of gold nanorods and saturated polyester in a powder state was obtained. Then, 5.0 parts by mass of an ester wax (peak temperature of the maximum endothermic peak in Differential Scanning Calorimetry (DSC) measurement=70 ℃, mn=704) was added to 100 parts by mass of the mixture, and the above materials were thoroughly mixed with an FM mixer (manufactured by Nippon spike & Engineering co., ltd.). Then, the mixture was melted and kneaded using a "PCM-30 type" (manufactured by Ikegai Corporation) with the temperature set to 130 ℃, thereby obtaining a kneaded material. The obtained kneaded material was spread in a sheet form on a water-cooled metal belt and quenched, and then coarsely pulverized to 1mm or less with a hammer mill, whereby a coarsely pulverized material was obtained. The coarsely crushed material was finely crushed with "T-250" (manufactured by Freund-Turbo Corporation). Further, classification was performed using "200TSP" (manufactured by Hosokawa Micron Corporation), whereby toner particles 1 having a weight average particle diameter of 5.9 μm were obtained.
< procedure of external addition >
The obtained toner particles 1 and hydrophobic silica fine powder surface-treated with hexamethyldisilazane (number average particle diameter of primary particles: 7 nm) were mixed with each other in amounts of 100.0 parts by mass and 1.0 parts by mass, respectively, using an FM mixer (manufactured by Nippon Coke & Engineering Co., ltd.).
[ production examples of toners 2 to 13, 15 to 18, 21, 22 ]
Toners 2 to 13, 15 to 18, 21 and 22 were obtained by performing operations similar to those of the production example of toner 1 except that the kind and amount of the gold nanorod dispersion liquid and the amount of the saturated polyester dispersion liquid were changed as shown in table 2. Table 2 shows physical properties of toners 2 to 13, 15 to 18, 21, and 22.
[ production example of toner 14 ]
< Process for producing aqueous Medium >
First, 1000.0 parts by mass of ion-exchanged water and 14.0 parts by mass of potassium phosphate-12 hydrate were injected into a reaction vessel, and kept at 65 ℃ for one hour under a nitrogen purge. Then, the solution was stirred at 12,000rpm using a high-speed stirrer "t.k.homomixer" (manufactured by PRIMIX Corporation). An aqueous solution of calcium chloride obtained by dissolving 9.2 parts by mass of calcium chloride-2 hydrate in 20.0 parts by mass of ion-exchanged water was injected all at once to prepare an aqueous medium containing a fine dispersion stabilizer.
< preparation Process of polymerizable monomer composition >
The mixture was obtained by mixing the following materials.
-44.8 parts by mass of gold nanorod dispersion liquid I
-128.9 parts by mass of styrene
-34.0 parts by mass of n-butyl acrylate
1.0 parts by mass of an aluminum salicylate compound (Bontron E-88,Orient Chemical Industries Co, manufactured by Ltd.)
5.0 parts by mass of a saturated polyester 2 (polycondensate of bisphenol A modified with propylene oxide and isophthalic acid, glass transition temperature 65 ℃, weight-average molecular weight 10,000, number-average molecular weight 6,000)
10.0 parts by mass of ester wax (melting point 73 ℃ C.)
-0.1 part by mass of divinylbenzene
The polymerizable monomer composition was prepared by maintaining the temperature of the mixture at 65℃and uniformly dissolving and dispersing the mixture at 500rmp using a T.K.homomixer.
< granulation Process >
The above-mentioned polymerizable monomer composition was put into an aqueous medium containing the above-mentioned dispersion stabilizer while maintaining the temperature of the aqueous medium at 70℃and the rotational speed of the T.K.homomixer at 12,000rpm, and 10.0 parts by mass of t-butyl peroxypivalate was added as a polymerization initiator. Thereafter, the resultant was granulated for 10 minutes while the rotation speed was maintained at 12,000rpm.
< polymerization Process >
After the granulation process, the polymerization process was carried out for 5 hours while stirring the solution at 150rpm using a propeller stirring blade instead of a stirrer, and the temperature was maintained at 70 ℃. Then, the temperature was raised to 85℃to heat the solution for two hours, thereby completing the polymerization reaction.
< washing and drying Process >
After the polymerization process was completed, the liquid was cooled to room temperature, and the pH of the solution was adjusted to pH 1.5 by adding dilute hydrochloric acid, and stirred for 3 hours. Thereafter, the filtration and washing processes are repeated, and a toner cake is obtained.
The resulting toner cake was chopped and then dried with an air flow dryer. Further, the toner cake was cut into fine powder and coarse powder with a multistage classifier utilizing the coanda effect, whereby toner particles 14 having a weight average particle diameter (D4) of 6.3 μm were obtained.
< procedure of external addition >
First, 100.0 parts by mass of the obtained toner particles 14 and 1.0 part by mass of hydrophobic silica fine powder (primary particles having a number average particle diameter of 7 nm) surface-treated with hexamethyldisilazane were mixed by a high-speed Mixer "FM Mixer" (manufactured by Nippon Coke & Engineering co., ltd.) to obtain toner 14. Table 2 shows the physical properties of the toner 14.
[ production example of toner 19 ]
Toner 19 was obtained by performing an operation similar to that in the production example of toner 1, except that gold nanorod dispersion D was used instead of gold nanorod dispersion a and 33.0 parts by mass of PEDOT-PSS dispersion was added in the production example of toner 1. Table 2 shows the physical properties of the toner 19.
[ production example of toner 20 ]
Toner 20 was obtained by performing operations similar to those in the production example of toner 1, except that gold nanorod dispersions F and H were used instead of gold nanorod dispersion a in the production example of toner 1, and 2.0 parts by mass of dispersion K (second gold nanorod dispersion) was added. Table 2 shows the physical properties of the toner 20. When the aspect ratio distribution of the gold nanorods contained in the toner 20 was measured, the average value μ in the aspect ratio distribution was 7.6, and the standard deviation σ was 2.1.
TABLE 2
The average value of the long axis lengths in table 2 is an average value of the long axis lengths of gold nanorods contained in the toner. The number ratio of gold nanoparticles is a ratio of the number of gold nanoparticles to the number of gold nanorods contained in the toner.
Example 1 ]
< evaluation of image quality in near-infrared region >
A color printer (trade name: LBP652C manufactured by Canon inc.) modified to arbitrarily change the development contrast was used as the image forming apparatus, and the toner in the black developing device was replaced with toner 1. An A4 paper (trade name: GF-C081, canon Marketing Japan inc.) was used as the output paper, and an image was output in an environment where the temperature was 25 ℃ and the relative humidity was 60%.
Fine line images (20 lines, line width 100 μm, pitch 500 μm, and line length 20 mm) were formed in the center portion of A4 paper using a black developing device. Next, using an A4 paper sheet on which a fine line image is formed and a yellow developing device, a yellow solid image is formed to cover the fine line image. Thus, an evaluation image was obtained.
Next, as shown in fig. 1, a light source 202 and a camera 203 are mounted, and an evaluation image 201 is observed. Specifically, the evaluation image was placed on a table in a stationary state, and irradiated with infrared rays at an angle of 15 ° with respect to the evaluation image using the light source 202 at a position about 1m from the evaluation image. The camera 203 is installed at a distance of 15cm right above the evaluation image, and captures the evaluation image. As the light source 202, a halogen lamp light source (trade name: PCS-UHX-150, manufactured by NIPPON p·ico ltd.) equipped with a visible light cut filter unit was used. As the camera 203, a near infrared camera (trade name: NVU3VD, inGaAs camera manufactured by IRspec Corporation) was used in which a filter cutting wavelength components of 800nm or less was attached to a lens unit. The spectral sensitivity wavelength range of the near infrared camera is 970 to 1650nm.
The captured image is displayed on a display to check 20 thin lines formed at the center portion of the evaluation image, and count the number of thin lines that are complete and continuous over the entire length and can be clearly observed. Then, the image quality of the thin line image is evaluated based on the counted number of thin lines. Table 3 shows the results. It was determined that when the count number of the thin lines was 13 or more, an advantageous effect was obtained.
< evaluation of invisibility in visible light region >
< method for measuring absorbance of light in wavelength range of 400nm to 800nm >
The loading amount using the image forming apparatus and the toner 1 was 0.30mg/cm 2 The A4 paper of (2) forms a rectangular image of 1cm by 10cm, thereby obtaining a sample image.
In the above sample image, spectral measurement in the wavelength range of 400nm to 800nm was performed using a photometer, and the maximum absorbance in the measurement was set as a measured value (%) of the sample image. As the photometer, an ultraviolet-visible-near infrared spectrophotometer (trade name: UV-3600, manufactured by Shimadzu Corporation) equipped with an integrating sphere attachment (trade name: ISR-240A, manufactured by Shimadzu Corporation) was used. Spectral measurements were also performed on a single sheet (paper with no image formed thereon) as a blank.
The value obtained by subtracting the blank measurement value (%) from the measurement value (%) of the sample image is set as the visible light absorbance (%), and the invisibility of the toner is evaluated using the visible light absorbance (%). Table 3 shows the results. When an image having a visible light absorptivity of 11% is visually inspected, it is determined that the quality of the image is sufficient for use as an invisible image. When an image having a visible light absorptivity of 13% is visually inspected, it is determined that the quality of the image is insufficient for use as an invisible image.
< evaluation of near-infrared region reading Performance >
< method for measuring absorbance of light in the wavelength range of 900nm to 1800nm >
On the sample image for the invisibility evaluation, spectroscopic measurement was performed in a wavelength range of 900nm to 1800nm using an ultraviolet-visible-near infrared spectrophotometer (trade name: manufactured by MV-3300,JASCO Corporation). The maximum absorbance in the measurement is set as the measured value of the sample image. Spectral measurement was also performed on a single sheet as a blank, and a value obtained by subtracting a measurement value of the blank from a measurement value of a sample image was set as an infrared absorption rate (%). Table 3 shows the results. When an image having an infrared absorption of 3% is inspected using a camera, it is determined that the quality of the image is sufficient to read as an invisible image. However, when an image having an infrared absorption of 2% is inspected using a camera, it is determined that the quality of the image is insufficient for reading as an invisible image. It was also determined that the advantageous effects of the present disclosure were obtained for images in which the ratio of infrared absorption rate (%) to visible light absorption rate (%) was 1.50 or more. Table 3 shows the results.
< method for measuring light transmittance in wavelength range of 400nm to 800nm >
The loading amount of toner 1 was 0.30mg/cm 2 A rectangular image of 1cm by 10cm was formed on a PET film (trade name: lumirrorT 60 (manufactured by Toray Industries, inc.)) to thereby obtain a sample image.
On the above sample image, spectral measurement was performed in a wavelength range of 400nm to 800nm using a photometer, and the maximum transmittance in the measurement was set as a measurement value (%) of the sample image. Spectral measurements were also performed on a single PET film (PET film on which no image was formed) as a blank. The value obtained by subtracting the blank measurement value (%) from the measurement value (%) of the sample image is set as the visible light transmittance (%). Table 3 shows the results.
< examples 2 to 20 and comparative examples 1 and 2>
Evaluation was performed in the same manner as in example 1 except that toner 1 and toners 2 to 22 were changed as shown in table 3. Table 3 shows the results.
TABLE 3
The present invention is not limited to the above-described exemplary embodiments, and various changes and modifications may be made without departing from the spirit and scope of the present invention. Accordingly, the appended claims are attached to disclose the scope of the invention.
The present application is based on and claims the benefit of priority of Japanese patent application Nos. 2021-012778 filed on 29 of 2021 and 2021-151226 filed on 16 of 2021, 9, the disclosures of which are incorporated herein by reference in their entireties.

Claims (14)

1. A toner includes toner particles,
characterized in that the toner comprises gold nanorods, and
wherein, in the case of measuring an aspect ratio distribution of gold nanorods contained in the toner, an average μ in the aspect ratio distribution is in a range of 6.0 to 13.0, and a standard deviation σ in the aspect ratio distribution is in a range of 0.5 to 4.5.
2. The toner according to claim 1, wherein the standard deviation σ is in a range of 0.5 to 2.5.
3. The toner according to claim 1 or 2, wherein the average value μ is in a range of 8.0 to 11.0, and the standard deviation σ is in a range of 0.5 to 2.5.
4. The toner according to any one of claims 1 to 3, wherein a content ratio of gold nanorods contained in the toner is in a range of 0.005 to 0.200 mass%.
5. The toner according to any one of claims 1 to 4, wherein the toner does not contain gold nanoparticles, or contains gold nanoparticles at a ratio of 15% by number or less relative to the number of gold nanorods contained in the toner.
6. The toner according to any one of claims 1 to 5, wherein the toner particles have a weight average particle diameter D4 of 4.0 μm or more and 9.0 μm or less.
7. The toner according to any one of claims 1 to 6, wherein an average value of long axis lengths of gold nanorods contained in the toner is 1/4 or less of a weight average particle diameter D4 of the toner particles.
8. The toner according to any one of claims 1 to 7, wherein an average value of long axis lengths of gold nanorods contained in the toner is in a range of 50 to 110 nm.
9. The toner according to any one of claims 1 to 8, wherein the toner further contains poly (3, 4-ethylenedioxythiophene) -poly (styrenesulfonic acid), PEDOT-PSS.
10. The toner according to any one of claims 1 to 9, wherein, at a toner loading amount of 0.30mg/cm 2 In the case of using a toner, the maximum value of the absorbance of light in the wavelength range of 400nm to 800nm is 10% or less in the spectral analysis of a fixed image formed.
11. The toner according to any one of claims 1 to 10, wherein, at a toner loading amount of 0.30mg/cm 2 In the case of using a toner, the maximum value of the absorbance of light in the wavelength range of 900nm to 1800nm is 5% or more in the spectral analysis of a fixed image formed.
12. The toner according to any one of claims 1 to 11, wherein, at a toner loading amount of 0.30mg/cm 2 In the case of using a toner, the maximum value of the light transmittance in the wavelength range of 400nm to 800nm is 90% or more in the spectral analysis of a fixed image formed by using the toner.
13. The toner according to any one of claims 1 to 12, wherein the toner is a toner for invisible image formation.
14. An image reading method, characterized in that it comprises:
a step of reading an image formed with the toner according to any one of claims 1 to 13 using an apparatus equipped with a near infrared sensor.
CN202280012088.1A 2021-01-29 2022-01-26 Toner and image reading method Pending CN116762043A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2021-012778 2021-01-29
JP2021-151226 2021-09-16
JP2021151226A JP2022117406A (en) 2021-01-29 2021-09-16 Toner and image reading method
PCT/JP2022/002904 WO2022163709A1 (en) 2021-01-29 2022-01-26 Toner and method for reading image

Publications (1)

Publication Number Publication Date
CN116762043A true CN116762043A (en) 2023-09-15

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Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
CN (1) CN116762043A (en)

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