JP2010217817A - Image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method that forms an image in decoration color and also suppresses image defect in the formed image. <P>SOLUTION: The image forming method includes forming a particle image on an image support using coloration particles including: a piece of color display layer which comprises at least particles for structural color and matrix and which develops the structural color; and a thermoplastic resin; and fixing the particle image by heat treatment. In the method, the particle image is preferably formed by an electrophotographic method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming method using colored particles that express structural colors.

In the printing field, for example, there is a demand for a home party guide letter by a full-color printer, a small-scale store flyer, creation of advertisements, and the like. In many cases, a color with a rich decorative property (hereinafter, also referred to as “decorative color”) such as gold, silver, pearl, or the like is desired as the color used for these.
In order to print such gold, silver, and pearl colors, for example, image forming materials such as toner containing metal as a colorant have been proposed (see, for example, Patent Documents 1 and 2).

  However, in order to exhibit a desired color by such an image forming material, a large amount of colorant must be introduced per unit area. Therefore, when fixing by heating, a fixing agent such as a binder resin is used. There is a problem that thermal deformation is hindered and fixing property is lowered, and as a result, an image defect or the like occurs in the formed image.

JP 2008-139464 A JP 2006-308673 A

  The present invention has been made on the basis of the above circumstances, and an object of the present invention is to be able to form an image with a decoration color and to suppress the image loss of the formed image. An object of the present invention is to provide an image forming method that can be used.

  The image forming method of the present invention forms a particle image on an image support by using colored particles including at least a color display layer composed of structural color particles and a matrix and expressing a structural color, and a thermoplastic resin. The particle image is fixed by heat treatment.

  In the image forming method of the present invention, the particle image is preferably formed by an electrophotographic method.

  In the image forming method of the present invention, the color display layer piece preferably has a major axis diameter of 3 to 75 μm and a minor axis diameter of 1 to 50 μm.

  In the image forming method of the present invention, in the particle image formed on the image support, the content of the color display layer piece in the colored particles is in the range of 0.1 to 50% by mass. Can do.

  In the image forming method of the present invention, when the structural color particles constituting the color display layer piece related to the colored particles are made of a resin, the resin constituting the structural color particles is the heat treatment. It is preferable that it has a glass transition temperature (Tg) higher than the temperature.

  In the image forming method of the present invention, it is preferable that the thermoplastic resin constituting the colored particles has a softening point temperature (Tsp) equal to or lower than the temperature of the heat treatment.

  Further, in the image forming method of the present invention, when the structural color particles constituting the color display layer piece relating to the colored particles are made of a resin and the matrix is air, the structural color particles It is preferable that the resin constituting the colorant and the thermoplastic resin constituting the colored particles are incompatible with each other.

  In the image forming method of the present invention, the material constituting the matrix constituting the color display layer piece relating to the colored particles and the thermoplastic resin constituting the colored particles are incompatible with each other. It is preferable that

  Furthermore, in the image forming method of the present invention, a colorant may be contained in a portion of the colored particles containing a thermoplastic resin.

According to the image forming method of the present invention, since the specific colored particles including the color display layer piece that expresses the structural color are used, the amount of the colored particles required for forming a decorative color image having a desired luminance is small. Therefore, even when the particle image is fixed by heat treatment, the inhibition of thermal deformation of the material related to fixing is suppressed, and thus a high-quality image in which image defects are suppressed can be stably obtained. .
In particular, according to the image forming method using colored particles made of resin as the structural color particles constituting the color display layer piece, there is no need to use a substance that inhibits thermal deformation of a material related to fixing, such as metal. In addition, it is possible to reliably obtain a high-quality image with image defects suppressed.

It is a perspective view for explanation which shows typically an example of composition of a colored particle used for an image forming method of the present invention. It is sectional drawing for description which shows typically the cross section of the color display layer piece which comprises the colored particle | grains of FIG. It is sectional drawing for description which shows typically the cross section of another example of the color display layer piece used for the image forming method of this invention. It is an explanatory perspective view showing typically another example of the composition of the colored particles used in the image forming method of the present invention. It is explanatory drawing for demonstrating the image forming method of this invention.

  Hereinafter, the present invention will be specifically described.

In the image forming method of the present invention, a particle image is formed on an image support by colored particles including at least a structural color particle and a matrix and a color display layer piece expressing a structural color and a thermoplastic resin. In this method, the particle image is fixed by heat treatment.
According to such an image forming method, an image colored with a decorative color having an appropriate structural color can be obtained.

[Colored particles]
FIG. 1 is an explanatory perspective view schematically showing an example of the configuration of colored particles used in the image forming method of the present invention.
The colored particles 10 used in the image forming method of the present invention are those in which the color display layer piece 11 expressing a structural color is contained in the fixing layer 20 containing at least a thermoplastic resin. No. 10 may be used, for example, in an image forming method of an electrophotographic method in a state in which an external additive composed of an appropriate post-treatment agent is added in order to improve various properties such as fluidity and chargeability.

The content of the color display layer piece 11 in the colored particles 10 is, for example, 0.1 to 50% by mass. When the content of the color display layer piece 11 in the colored particles 10 is within the above range, an image free from image defects can be obtained without hindering thermal deformation of the thermoplastic resin during fixing.
On the other hand, when the content of the color display layer piece 11 in the colored particles 10 is less than 0.1% by mass,
There is a possibility that it is difficult to form a decorative color image having a desired luminance, and when the content of the color display layer piece 11 exceeds 50% by mass, more heat energy is required for fixing. There is a fear.

  The particle size of the colored particles 10 used in the image forming method of the present invention varies depending on the specific method of the image forming method, such as an electrophotographic method or a powder coating method. The thickness is preferably 100 μm, more preferably 5 to 30 μm.

The volume-based median diameter is measured and calculated using a device in which a computer system for data processing is connected to “Multisizer 3” (manufactured by Beckman Coulter, Inc.).
Specifically, 0.02 g of the colored particles is added to 20 ml of a surfactant solution (for example, a surfactant solution obtained by diluting a neutral detergent containing a surfactant component 10 times with pure water for the purpose of dispersing colored particles. ), Ultrasonic dispersion is performed for 1 minute to prepare a sample dispersion, and this sample dispersion is placed in a beaker containing “ISOTON II” (manufactured by Beckman Coulter) in a sample stand. Pipette until 8% and measure with a measuring machine count of 2500. The aperture size of the multisizer 3 is 50 μm.

[Color display layer piece]
The color display layer piece 11 has a specific size of a major axis diameter of preferably 3 to 75 μm, more preferably 10 to 30 μm, and a minor axis diameter of preferably 1 to 50 μm, more preferably 5 to 5 μm. 15 μm.
The major axis diameter and the minor axis diameter of the color display layer piece 11 are obtained by taking a photograph of the color display layer piece 11 with a scanning electron microscope at a magnification such that the area ratio of the colored particles to the frame area of the photograph is 2%. The major axis diameter and minor axis diameter of 100 color display layer pieces 11 in the photographic image are measured by an image processing analysis apparatus “Luzeck IID” (manufactured by Nireco Co., Ltd.). Is.
The major axis diameter refers to the maximum diameter of the colored particles in the photographic image, and the minor axis diameter refers to the maximum length among the diameters perpendicular to the major axis diameter. Here, the maximum diameter means the width of the colored particles that maximizes the interval between the parallel lines when the image of the colored particles is sandwiched between two parallel lines.

  The color display layer piece 11 constituting the colored particles 10 is formed by forming the periodic structure 16 in the matrix M, and such a periodic structure is formed in the color display layer piece 11. Chromatic colors are perceived by irradiation with visible light.

Specifically, as shown in FIG. 2, the color display layer pieces 11 are structural color particle layers that are regularly formed, for example, by contacting the structural color particles 12 made of solid particles in the surface direction. 15 has a configuration in which the structural color particles 12 are regularly arranged in the thickness direction in contact with each other.
For example, when the matrix M is solid, the structural color particles 12 are regularly arranged in a non-contact state in the surface direction in the matrix M as shown in FIG. The structural color particle layer 15 may have a configuration in which the structural color particles 12 are regularly arranged in a non-contact state even in the thickness direction.
The structural color particle layer 15 has a configuration in which the structural color particles 12 are regularly arranged in one direction with respect to the direction in which light is incident. In particular, the periodic structure has a face-centered cubic structure or the like. It is preferable that the structural color particles 12 are arranged so as to exhibit a close-packed structure such as a cubic close-packed structure or a hexagonal close-packed structure.

In the color display layer piece 11, the absolute value of the difference between the refractive index of the structural color particles 12 and the refractive index of the matrix M (hereinafter referred to as “refractive index difference”) is 0.02 to 2.0. It is preferably 0.1 to 1.6.
The matrix M is air, and the material constituting the fixing layer 20 has a characteristic of being filled between the structural color particles 12 constituting the color display layer piece 11 by being melted by heating at the time of fixing. In this case, the difference in refractive index between the refractive index of the structural color particles 12 and the refractive index of the thermoplastic resin constituting the fixing layer 20 may be within the above range. Further, when the material constituting the matrix M and the thermoplastic resin constituting the fixing layer 20 are compatible with each other, the refraction between the refractive index of the compatible substance and the refractive index of the structural color particles 12 is obtained. It is only necessary that the rate difference is within the above range.
When this difference in refractive index is less than 0.02, the structural color is difficult to develop, and when this difference in refractive index is greater than 2.0, the structural color becomes white turbid due to large scattering of light. The display color is difficult to recognize.

The thickness of the structural color particle layer 15 in the color display layer piece 11 is preferably 0.1 to 100 μm, for example.
When the thickness of the structural color particle layer is less than 0.1 μm, the resulting structural color is thin, while when the thickness of the structural color particle layer is greater than 100 μm, light scattering is greatly generated. As a result, the structural color becomes cloudy and the display color becomes difficult to recognize.

The period number of the structural color particle layer 15 in the color display layer piece 11 needs to be at least 1 or more, preferably 5 to 500.
When the number of periods is less than 1, the color display layer piece does not develop a structural color.

  In the image obtained by the image forming method of the present invention, the display color based on the structural color is a color having a peak wavelength in the visible range.

The layer interval D in the color display layer piece 11 is preferably 50 to 500 nm.
When the layer distance D is in the above range, the structural color expressed in the obtained color display layer piece 11 becomes a display color having a peak wavelength in the visible range. On the other hand, when the layer distance D is larger than 500 nm, the obtained color display layer piece 11 may not exhibit a structural color.

[Structural color]
The structural color obtained in the color display layer piece 11 is not a color due to light absorption of a pigment or the like but a color expressed by selective light reflection due to a periodic structure or the like.
The color display layer piece 11 has a structure in which light can be reflected by the color display layer piece 11, and light having a wavelength defined based on the observation angle is selectively reflected. The appearance of color is visible.

The light selectively reflected by the color display layer piece 11 is light having a wavelength represented by the following formula (1) based on Bragg's law and Snell's law.
In addition, the following formula (1) and the following formula (2) are approximate formulas, and in practice, these calculated values may not completely match.
Formula (1): λ = 2 nD (cos θ)
In this formula (1), λ is the peak wavelength of the structural color, n is the refractive index of the color display layer piece 11 represented by the following formula (2), and D is the layer spacing of the structural color particle layer 15 (for structural color). (Interval in the perpendicular direction of the color display layer piece 11 of the particles 12), θ is an observation angle with the perpendicular of the color display layer piece 11.
Formula (2): n = {na · c} + {nb · (1-c)}
In this formula (2), na is the refractive index of the structural color particles 12, nb is the refractive index of the matrix M, and c is the volume ratio of the structural color particles 12 in the color display layer piece 11.
Here, the peak wavelength λ of the structural color can be measured using “MCPD-3700” (manufactured by Otsuka Electronics Co., Ltd.) that can confirm the relationship between the reflection light source and the observation angle using a fiber.

  In the formed image, when the substance filled between the structural color particles 12 of the color display layer piece 11 is different from the matrix M constituting the color display layer piece 11, in the formed image, The resulting structural color can be calculated by changing the refractive index of the matrix M to the refractive index of the substance in the above formula (2).

[Structural color particles]
In the present invention, the structural color particles are preferably substances having a roughly spherical shape in three dimensions. This substance is preferably in a solid form, but if the matrix M is in a solid form and is not deformed by heat for fixing and pressure applied as necessary, the substance is a gas. It may be in the form of a liquid or liquid. When the substance is in a liquid state, the boiling point is preferably larger than the heat for fixing.
When the structural color particles 12 are solid, the structural color particles 12 are not deformed by heat for fixing and pressure applied as necessary.

The material constituting the structural color particles 12 of the color display layer piece 11 is preferably a resin having a glass transition temperature (Tg) higher than the temperature of the heat treatment in the image forming method of the present invention.
The material constituting the structural color particles 12 can be appropriately selected depending on the combination with the material for forming the matrix M.
Specifically, it is necessary that the refractive index is different from the refractive index of the material that forms the matrix M and that the material that forms the matrix M is incompatible with each other. When the matrix M is air, the material constituting the structural color particles 12 is preferably incompatible with the thermoplastic resin constituting the fixing layer 20.
Further, as the material constituting the structural color particles 12, a material having high affinity with the material for forming the matrix M is preferable.

Examples of the structural color particles 12 constituting the color display layer piece 11 include various types.
Specifically, for example, styrene monomers such as styrene, methylstyrene, methoxystyrene, butylstyrene, phenylstyrene, chlorostyrene; methyl acrylate, ethyl acrylate, (iso) propyl acrylate, butyl acrylate, acrylic Acrylic acid ester or methacrylic acid ester monomer such as hexyl acid, octyl acrylate, ethyl hexyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethyl hexyl methacrylate; acrylic acid, methacrylic acid, itaconic acid, fumarate Examples thereof include particles obtained by polymerizing one kind of a polymerizable monomer such as a carboxylic acid monomer such as an acid, or organic particles comprising a resin obtained by copolymerizing two or more kinds.
The resin constituting the structural color particles 12 may be a polymer obtained by adding a crosslinkable monomer to a polymerizable monomer, and examples of the crosslinkable monomer include divinylbenzene, ethylene glycol diester. Examples thereof include methacrylate, tetraethylene glycol dimethacrylate, and trimethylolpropane trimethacrylate.
Moreover, for example, inorganic oxides and composite oxides such as silica, titanium oxide, aluminum oxide, and copper oxide, inorganic particles formed of glass, ceramics, and the like can be given.
Further, for example, core-shell type particles in which the above organic particles or inorganic particles are used as core particles, and a shell layer made of a material different from the material constituting the core particles is formed on the surface thereof. The shell layer can be formed using metal fine particles, metal oxide fine particles made of titania, metal oxide nanosheets made of titania, or the like.
Further examples include hollow particles obtained by removing the core particles from the core-shell particles by a method such as firing or extraction.
Of these particles, organic particles are preferably used.

The average particle size of the structural color particles 12 needs to be set in relation to the refractive index of the structural color particles 12 and the refractive index of the matrix M, and at least the size of the dispersion becomes a stable colloidal solution. For example, the thickness is preferably 50 to 500 nm.
When the average particle diameter of the structural color particles 12 is in the above range, the dispersion can be made into a stable colloidal solution, and the structural color expressed in the resulting color display layer piece 11 is visible. The color has a peak wavelength.
On the other hand, when the average particle diameter of the structural color particles is less than 50 nm, the visible structural color may have a low color density. When the average particle diameter of the structural color particles is larger than 500 nm, In some cases, the structural color that is visually recognized becomes white turbid due to the large scattering of light, and the display color is difficult to be recognized.

The CV value representing the particle size distribution is preferably 10 or less, more preferably 8 or less, and particularly preferably 5 or less.
When the CV value is larger than 10, the structural color particle layer to be regularly arranged is greatly disturbed, and the obtained color display layer piece becomes clouded and its structural color is difficult to recognize. May be.
The average particle size is 50,000 times using a scanning electron microscope “JSM-7410” (manufactured by JEOL Ltd.), and each of the 200 structural color particles 12 in this photographic image has a maximum length. Is obtained, and the number average value thereof is calculated. Here, the “maximum length” refers to the maximum distance between two points between any two points on the circumference of the structural color particle 12.
When the structural color particles 12 are photographed as aggregates, the maximum length of primary particles (structural color particles) forming the aggregates is measured.
The CV value is calculated from the following formula (CV) using the standard deviation in the number-based particle size distribution and the above average particle size value.
Formula (CV): CV value (%) = ((standard deviation) / (average particle size)) × 100

The refractive index of the structural color particles 12 can be measured by various known methods, and the refractive index of the structural color particles 12 in the present invention is a value measured by an immersion method.
As specific examples of the refractive index of the structural color particles 12, for example, polystyrene is 1.59, polymethyl methacrylate is 1.49, polyester is 1.60, fluorine-modified polymethyl methacrylate is 1.40, polystyrene. -Butadiene copolymer 1.56, polymethyl acrylate 1.48, polybutyl acrylate 1.47, silica 1.45, titanium oxide (anatase type) 2.52, titanium oxide (rutile type) Is 2.76, copper oxide is 2.71, aluminum oxide is 1.76, barium sulfate is 1.64, and ferric oxide is 3.08.

  The structural color particles 12 constituting the structural color particle layer 15 may be a single composition or a single composition, but the structural color particles are bonded to the surface of the structural color particles. The material to be adhered may be attached, or the material for adhering the structural color particles may be introduced into the structural color particles. By using such an adhesive substance, structural color particles can be adhered to each other even if the structural color particles are made of a substance that hardly causes self-alignment or the like when the structural color particle layer 15 is formed. Further, when the structural color particles are formed of a material having a high refractive index, a low refractive index substance may be internally added.

The structural color particles 12 constituting the structural color particle layer 15 are preferably highly monodispersed because they are easily arranged regularly when forming the structural color particle layer 15.
In order to obtain structural color particles having high monodispersity, when the structural color particles are organic particles, the structural color particles are usually used in a soap-free emulsion polymerization method, suspension polymerization method, emulsification It is preferably obtained by a polymerization method such as polymerization.

  The structural color particles 12 may be subjected to various surface treatments in order to increase the affinity with the matrix M.

〔matrix〕
The matrix M constituting the color display layer piece 11 may be in a gaseous state or in a solid state. When the matrix M is solid, the resulting color display layer piece 11 has high strength, structural color particle peeling inhibiting ability, and flexibility.
The material for forming the matrix M may be a substance different from the thermoplastic resin constituting the fixing layer 20 of the colored particles 10, or the same substance as shown in FIG. The region between the structural color particles 12 of the piece 11 may also be the fixing layer 20, but if it is a different substance, it may be incompatible with the thermoplastic resin constituting the fixing layer 20. preferable.
In the case where the matrix M is solid, a material whose refractive index is different from that of the structural color particles 12 can be appropriately selected as a material for forming the matrix M. As a material for forming the matrix M, a material having high affinity with the structural color particles 12 is preferable.
Further, when the material for forming the matrix M is a substance different from the thermoplastic resin constituting the fixing layer 20, it may be melted by heat treatment relating to fixing, or may not be melted. Good.
When the matrix M is solid and the structural color particles 12 are gaseous or liquid, the matrix M is not deformed by heat for fixing and pressure applied as necessary. Is done.

When the matrix M is solid, the refractive index of the matrix M can be measured by various known methods. In the present invention, the refractive index of the matrix M is a thin film made of only the matrix M separately. And this thin film was measured with an Abbe refractometer.
Specific examples of the refractive index of the matrix include 1.41 for silicone gel, 1.53 for gelatin / gum arabic, 1.51 for polyvinyl alcohol, 1.51 for sodium polyacrylate, and fluorine-modified acrylic resin. 1.34, poly N-isopropylacrylamide is 1.51, and foamed acrylic resin is 1.43.

Examples of materials to form the matrix M when the matrix M is solid include resins, hydrogels, oil gels, photocuring agents, thermosetting agents, and moisture curing agents.
Specific examples of resins that are soluble in organic solvents include polystyrene resins, acrylic resins, and polyester resins. Examples of resins that are soluble in water include polyacrylic acid, polyvinyl alcohol, and polyvinyl chloride. Is mentioned.
Specific examples of hydrogels include gels obtained by mixing gelatin, carrageenan, polyacrylic acid, sodium polyacrylate and other gelling agents with water, and oil gels include silicone gels and fluorine-modified silicone gels. And gels obtained by mixing gelling agents such as amino acid derivatives, cyclohexane derivatives and polysiloxane derivatives with silicone oil and organic solvents.

[Method for producing color display layer piece]
Such a color display layer piece 11 is, for example, a period in which an aqueous dispersion of structural color particles 12 is prepared, applied to the surface of a substrate or the like and self-aligned, and the structural color particles 12 are regularly arranged. After the structure 16 is formed and dried, if necessary, a solution for forming the matrix M prepared in a liquid form is applied to the periodic structure 16 and filled between the structural color particles 12 without any gaps. It can be solidified and peeled from the substrate to obtain a large piece of the color display layer, which can be produced by a method of pulverizing and classifying it.

As the substrate, for example, rubber, glass, ceramics, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) film or sheet can be used.
When the color display layer piece 11 is produced using an aqueous dispersion of structural color particles 12, the substrate preferably has a surface contact angle with water that is somewhat low. Moreover, since a thing with high surface smoothness is preferable, you may perform an appropriate surface treatment about a board | substrate. Moreover, it can also be used in a state where the structural color particles are easily adhered by blasting or the like.

  As an application method of the aqueous dispersion of the structural color particles 12, a screen coating method, a dip coating method, a spin coating method, a curtain coating method, an LB (Langmuir-Blodgett) film forming method, or the like can be used.

For pulverizing the large pieces of the color display layer, for example, “Hammer Mill” (manufactured by Hosokawa Micron Corporation), “Turbo Mill T-400 Model” (manufactured by Turbo Industry Co., Ltd.) or the like can be used.
For classification, for example, an air classifier can be used.

(Fixing layer)
The fixing layer 20 in the colored particles 10 used in the image forming method of the present invention contains at least a thermoplastic resin, and the thermoplastic resin has a softening point temperature (not more than the temperature of the heat treatment in the image forming method of the present invention). Tsp).

  Examples of the thermoplastic resin constituting the fixing layer 20 include styrene resins, (meth) acrylic resins, styrene- (meth) acrylic copolymer resins, vinyl resins such as olefin resins, polyester resins, and polyamide resins. Examples include various known thermoplastic resins such as resins, polycarbonate resins, polyethers, polyvinyl acetate resins, polysulfone resins, polyurethane resins, and the like. In particular, in order to improve transparency, styrene-based resins, acrylic resins, and polyester-based resins having high transparency, low melting properties, and high sharp melt properties are preferable. These can be used alone or in combination of two or more.

  The content of the thermoplastic resin is 50 to 100% by mass in the fixing layer 20. When the content of the thermoplastic resin is less than 50% by mass in the fixing layer, the thermal deformation of the thermoplastic resin is hindered when fixing by heating, and the fixability is lowered. There is a risk of image loss.

  The softening point temperature (Tsp) of the thermoplastic resin is preferably 70 to 140 ° C., for example.

The softening point temperature (Tsp) of the thermoplastic resin is measured as follows.
That is, first, in an environment of 20 ° C. and 50% RH, 1.1 g of a thermoplastic resin was placed in a petri dish, leveled, and allowed to stand for 12 hours or more. Then, a molding machine “SSP-10A” (manufactured by Shimadzu Corporation) was used. Pressurized with a force of 3820 kg / cm ² for 30 seconds to prepare a cylindrical molded sample having a diameter of 1 cm. Then, the molded sample was subjected to a flow tester “CFT-500D” in an environment of 24 ° C. and 50% RH ( Shimadzu Corporation) with a load of 196 N (20 kgf), a starting temperature of 60 ° C., a preheating time of 300 seconds, and a heating rate of 6 ° C./min. extruded from the time of preheating ends with piston, offset method temperature T _offset measured by setting the offset value 5mm at a melt temperature measurement method of temperature ramps are thermoplastic soft It is the point temperature (Tsp).

  The thermoplastic resin preferably has a number average molecular weight (Mn) measured by gel permeation chromatography (GPC) of 3,000 to 6,000, more preferably 3,500 to 5,500, and a weight average molecular weight. The ratio Mw / Mn between (Mw) and the number average molecular weight (Mn) is preferably 2.0 to 6.0, more preferably 2.5 to 5.5, and the glass transition temperature (Tg) is preferred. Is 40-70 degreeC, More preferably, it is 45-65 degreeC.

The molecular weight measurement by GPC is performed as follows. That is, using an apparatus “HLC-8220” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZM-M3 series” (manufactured by Tosoh Corporation), while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) was used as a carrier solvent at a flow rate of 0. 2 ml / min, and the thermoplastic resin is dissolved in tetrahydrofuran to a concentration of 1 mg / ml under a dissolution condition in which the treatment is performed for 5 minutes using an ultrasonic disperser at room temperature, and then the membrane is filtered with a membrane filter having a pore size of 0.2 μm. A sample solution is obtained by processing, 10 μL of this sample solution is injected into the apparatus together with the above carrier solvent, detected using a refractive index detector (RI detector), and the molecular weight distribution of the measurement sample is monodispersed polystyrene Calculate the molecular weight using a calibration curve measured using standard particles. Put out. As standard polystyrene samples for preparing a calibration curve, molecular weights of 6 × 10 ² , 2.1 × 10 ³ , 4 × 10 ³ , 1.75 × 10 ⁴ , 5.1 × 10 ⁴ , 1 manufactured by Pressure Chemical are used. .1 × 10 ⁵ , 3.9 × 10 ⁵ , 8.6 × 10 ⁵ , 2 × 10 ⁶ , 4.48 × 10 ⁶ , and at least about 10 standard polystyrene samples were measured, and a calibration curve Create A refractive index detector is used as the detector.

  The glass transition temperature (Tg) is measured using a differential scanning calorimeter “DSC-7” (manufactured by PerkinElmer) and a thermal analyzer controller “TAC7 / DX” (manufactured by PerkinElmer). . Specifically, 4.50 mg of thermoplastic resin is sealed in an aluminum pan “KITNO.0219-0041”, which is set in a sample holder of “DSC-7”, and an empty aluminum pan is used for reference measurement. Heat-cool-Heat temperature control is performed at a measurement temperature of 0 to 200 ° C. under measurement conditions of a temperature increase rate of 10 ° C./min and a temperature decrease rate of 10 ° C./min. Data on Heat is acquired, and the glass transition point is the intersection of the baseline extension before the rise of the first endothermic peak and the tangent line indicating the maximum slope between the rise of the first endothermic peak and the peak apex. It was shown as temperature (Tg). 1st. The heat was raised at 200 ° C. for 5 minutes.

  The fixing layer 20 used in the image forming method of the present invention may contain a wax or a colorant in addition to the thermoplastic resin.

The wax that can be contained in the fixing layer 20 is not particularly limited, and various known waxes can be used.
The melting point of the wax varies depending on the temperature of the heat treatment in the image forming method, but is preferably 60 to 100 ° C., and more preferably 65 to 85 ° C., for example.
The melting point of the wax indicates the temperature at the top of the endothermic peak, and the differential scanning calorimeter “DSC-7” (manufactured by PerkinElmer) and the thermal analyzer controller “TAC7 / DX” (manufactured by PerkinElmer) DSC is measured by analysis.
Specifically, 4.5 mg of wax was sealed in an aluminum pan (KITNO.0219-0041), set in a sample holder of “DSC-7”, measured at 0 to 200 ° C., and heated at a rate of 10 Heat-cool-Heat temperature control was performed under the measurement conditions of ° C / min and a temperature drop rate of 10 ° C / min. Analysis is based on data in Heat. However, an empty aluminum pan is used for the reference measurement.

  The content of the wax is preferably 1 to 30% by mass in the fixing layer 20, and more preferably 5 to 20% by mass. By setting the content of the wax within the above range, the obtained image 25 (see FIG. 4B) can obtain a uniform and high gloss.

  The colorant that can be contained in the fixing layer 20 is not particularly limited, and various known dyes and pigments can be used.

  The content of the colorant can be 0 to 10% by mass in the fixing layer 20. When the content of the colorant exceeds 10% by mass in the fixing layer, the colorant obtained may cause liberation of the colorant, which may affect the chargeability.

The fixing layer 20 used in the image forming method of the present invention is translucent.
Here, the translucent fixing layer refers to a layer that does not completely obstruct the viewing of the structural color related to the color display layer piece even when the color display layer piece is viewed through the fixing layer.

(Image forming method)
FIG. 5 is an explanatory diagram for explaining the image forming method of the present invention.
In the image forming method of the present invention, the particle image forming step for electrostatically forming the particle image 23 on the image support P using the colored particles 10, and the particle image 23 on the image support P are heated. The fixing agent layer 27 containing at least the thermoplastic resin of the fixing layer 20 constituting the colored particles 10 is formed through the heat fixing step of fixing by the above, whereby the image 25 is obtained.
In the image 25, the entire color display layer piece 11 is not limited to being buried in the fixing agent layer 27, and each color display layer piece 11 only needs to be fixed in a state where it is not detached from the image support P. .

[Particle image forming step]
In this particle image forming step, various known methods can be adopted as a method for electrostatically forming the particle image 23 on the image support P. For example, a static image can be formed on the photoreceptor by electrophotography. An object to be grounded by charging the colored particles 10 and the fixing particles 20 using a spray gun by a method of forming an electrostatic latent image and transferring it to the image support P or by a powder coating method. And a method of applying by static electricity.

[Heat fixing process]
As the heat treatment method in the heat fixing step, various known methods can be used without limitation, and examples thereof include a method such as heat roller fixing by an electrophotographic method.
The temperature of the heat treatment may be any temperature that is higher than the softening point temperature (Tsp) of the thermoplastic resin that constitutes the fixing layer 20, and may be, for example, 100 to 250 ° C.

  In this heat-fixing step, in addition to heat, other external stimuli that do not involve deformation of the structural color particles 12 such as pressure and light irradiation may be further applied.

(Image support)
Examples of the image support P used in the image forming method of the present invention include plain paper from thin paper to thick paper, high-quality paper, coated printing paper such as art paper or coated paper, commercially available Japanese paper or postcard paper, Various examples such as a plastic film and cloth for OHP can be mentioned, but the invention is not limited thereto.

According to the image forming method as described above, since the specific colored particles 10 including the color display layer pieces 11 that express the structural colors are used, the colored particles 10 required for forming a decorative color image having a desired luminance are used. Since the amount is small, even when the particle image 23 is fixed by heat treatment, inhibition of thermal deformation of the material related to fixing is suppressed, and thus a high-quality image 25 in which image defects are suppressed is stabilized. Can be obtained.
In particular, according to the image forming method using the colored particles 10 in which the structural color particles 12 constituting the color display layer piece 11 are made of a resin, it is necessary to use a substance that inhibits thermal deformation of a material related to fixing, such as metal. Therefore, it is possible to reliably obtain a high-quality image 25 in which image loss is suppressed.

  Although the embodiments of the present invention have been specifically described above, the embodiments of the present invention are not limited to the above examples, and various modifications can be made.

  Hereinafter, specific examples of the present invention will be described, but the present invention is not limited thereto. In the following, the average particle diameter and CV value of the structural color fine particles, the thickness in the surface direction of the toner particles, the major axis diameter and the minor axis diameter were measured by the same method as described above.

[Synthesis Example 1 of Structural Color Particles]
A monomer solution was prepared by heating 72 parts by mass of styrene, 20 parts by mass of n-butyl acrylate, and 8 parts by mass of acrylic acid to 80 ° C. On the other hand, after mixing a surfactant solution prepared by dissolving 0.2 parts by mass of sodium dodecylsulfonate in 263 parts by mass of ion-exchanged water at 80 ° C. and the above monomer mixture, (CLEARMIX) "(manufactured by M Technique Co., Ltd.) was subjected to a dispersion treatment for 30 minutes to prepare an emulsified dispersion.
The emulsified dispersion and 0.1 parts by weight of sodium dodecyl sulfonate were dissolved in 142 parts by weight of ion-exchanged water in a reaction vessel equipped with a stirrer, a heating / cooling device, a nitrogen introduction device, and a raw material / auxiliary charging device. The surfactant solution was charged, and the internal temperature was raised to 80 ° C. while stirring at a stirring speed of 200 rpm under a nitrogen stream. To this solution, 1.4 parts by mass of potassium persulfate and 54 parts by mass of water were added, and a dispersion of fine particles was obtained by performing polymerization for 3 hours, and this was separated into large / small particles by a centrifuge, A highly monodispersed dispersion of true spherical fine particles [1] was obtained. The structural color particles [1] in the dispersion [1] had an average particle size of 250 nm and a CV value of 5.

[Production example 1 of decorative color toner]
(1) Manufacture of color display layer pieces The above dispersion [1] is applied to a cleaned glass plate by a bar coating method, and dried for 20 minutes in an environment of a temperature of 20 ° C. and a humidity of 50% RH, and a thickness of 20 μm. A periodic structure having an area of 100 cm × 100 cm was formed, peeled off from the glass plate, pulverized at 15,000 rpm by a pulverizer “Turbomill pulverizer” (manufactured by Turbo Kogyo Co., Ltd.), and the Coanda effect was utilized. By performing classification with an airflow classifier, a color display layer piece [1] according to the present invention having a major axis diameter of 20 μm and a minor axis diameter of 5 μm was obtained.

(2) Production of thermoplastic resin 50 parts by mass of component A made of styrene and having a maximum molecular weight of 3,600 and a glass transition temperature of 62 ° C., 73 parts by mass of styrene, 25 parts by mass of n-butyl acrylate, and acrylic acid It consists of 2 parts by mass and has a maximum molecular weight of 100,000 and a glass transition temperature of 52 ° C., 20 parts by mass of B component, 80 parts by mass of styrene and 20 parts by mass of n-butyl acrylate, and a maximum molecular weight of 600,000. Then, 25 parts by mass of C component having a glass transition temperature of 60 ° C. was dissolved in xylene and mixed, and this resin solution was dried under reduced pressure to obtain a styrene acrylic resin [1].

(3) Granulation Resin: Styrene acrylic resin [1] 100 parts by weight Color display layer piece: Color display layer piece [1] 10 parts by weight Release agent: Natural gas Fischer-Tropsch wax (melting point 100 ° C.) From 4 parts by weight The material group C is mixed with a Henschel mixer for 20 minutes, then kneaded at a temperature of 115 ° C. using a twin-screw kneading extruder, and the volume-based median diameter is determined using a jet-type pulverizer and an air classifier. Colored particles [1] having a size of 20.0 μm were obtained. Decorative color toner [1] was obtained by mixing 100 parts by weight of the colored particles [1] and 0.6 parts by weight of hydrophobic silica “R-805” (manufactured by Aerosil) with a Henschel mixer.

[Manufacturing Examples 2-3 for Decorated Color Toner]
In the process of producing the color display layer piece of Production Example 1 of the decorative color toner, the color display layer piece having the major axis diameter and the minor axis diameter shown in Table 1, respectively, by appropriately changing the pulverization conditions [2] Decorative toners [2] to [3] having [3] to [3] were obtained.

[Production Examples 4 to 5 for decorative color toner]
In the same manner as in the granulating step of the decorative color toner production example 1, except that the addition amount of the color display layer piece [1] is changed to the amount shown in Table 2, the decorative color toner [4] to [5] was obtained.

[Production Example 6 for decorative color toner]
In the process of producing the color display layer piece of the decorative color toner production example 1, a periodic structure obtained by drying for 20 minutes in an environment of a temperature of 20 ° C. and a humidity of 50% RH is applied to a polycrystal having a refractive index of 1.36. A decorative color toner [6] having a color display layer piece [4] was obtained in the same manner except that (2,2,2-trifluoroethyl methacrylate) resin was filled.

[Production Example 7 for decorative color toner]
In the process for producing the thermoplastic resin of the decorative color toner production example 1, styrene having the maximum molecular weight of 10,000 was used as the component A to form the thermoplastic resin in the same manner. A decorative color toner [7] containing an acrylic resin [2] was obtained.

[Manufacture Example 8 for Decorated Color Toner]
The decorative color toner was manufactured in the same manner as in the granulating process of Production Example 1 except that 0.1 part by mass of carbon black “Regal 330R” (Cabot) was added to the material group C. A color toner [8] was obtained.

[Production Example 1 of Metallic Gloss Toner]
-420 parts by mass of polyester resin "FC-1198" (Mitsubishi Rayon Co., Ltd.)-174 parts by mass of yellow colorant "Hansa Yellow G Rhodamine 6C Lake Pigment" (manufactured by Clariant Japan)-Magenta colorant "Quinacridone pigment" (large (Manufactured by Nissei Kasei Co., Ltd.) 5.4 parts by mass • A raw material consisting of 0.6 parts by mass of a cyan colorant “phthalocyanine pigment” (manufactured by Dainichi Seika Co., Ltd.) is mixed with a super mixer, and after hot melt kneading with a biaxial kneader, The mixture was pulverized with a jet mill and then classified with a dry air classifier to obtain ocher toner base particles [x] having a volume average particle diameter (D50) of 9.0 μm. The volume average particle diameter (D50) is a volume-based integrated 50% value by “Coulter Counter TA-II” (manufactured by Beckman Coulter). The same applies to the following.
Then
-Toner base particle [x] 600 parts by mass-Polyester resin "FC-1198" (Mitsubishi Rayon Co., Ltd.) 2556 parts by mass-Pearl pigment "Pearl Glaze MM-100R" (Nihon Koken Co., Ltd.) 284 parts by mass-Carnauba wax 280 parts by weight of “Carnava No. 2 powder” (manufactured by Kato Yoko Co., Ltd.) ・ 80 parts by mass of the charge control agent “Bontron S-34” (manufactured by Orient Chemical Co., Ltd.) was dry-mixed for 20 minutes with a super mixer, and the twin-screw kneader “ PCM-65 ”(manufactured by Ikegai Co., Ltd.) was melt-kneaded at 120 to 160 ° C. to obtain a plate-like melt-kneaded product having a thickness of 2 to 3 mm. Next, the melt-kneaded product is pulverized by a jet mill and then classified by a dry air classifier to obtain a glossy toner having a volume average particle size of 9.0 μm. The following external additive is added to 100 parts by mass of the glossy toner. The agent was mixed with a 300 L Henschel mixer at a rotation speed of 1,220 rpm for 15 minutes to obtain a metallic glossy toner [x] exhibiting a gold color.
・ Silica (manufactured by Clariant Japan; average primary particle size 17.5 μm, specific surface area 140 m ^{2 /} g) 0.2 parts by mass ・ Resin fine powder “HYLAR461” (manufactured by AUSIMONT) 0.3 parts by mass ・ Titanium oxide (Japan) Manufactured by Aerosil; average primary particle size 10 nm, BET specific surface area 65 ± 10, treatment agent octylsilane) 0.5 parts by mass

[Production Example 2 of Metallic Gloss Toner]
A metallic glossy toner [y], which is made of a polyester resin vapor-deposited as a light reflecting material and a polyester resin colored with a yellow dye and which does not contain a release agent, was produced.

  By mixing 93 parts by mass of an acrylic-coated ferrite carrier with 7 parts by mass of the above decorative color toners [1] to [8] and metallic glossy toner [x], [y], decorative color development is performed. Agents [1] to [8], [x] and [y] were obtained.

<Examples 1-8, Comparative Examples 1-2>
The decorative color toners [1] to [8] and the metallic glossy toners [x] and [y] have a pixel ratio of the decorative color toner of 30% by the copying machine “Bizhub C 650” (manufactured by Konica Minolta Business Technologies). A half-tone image is formed, and the monitor is visually observed by five people who select the image quality arbitrarily, and the metal gloss and image defect are subjected to sensory evaluation according to the following evaluation criteria. Evaluated according to many evaluation criteria. In both evaluations of metallic luster and image loss, the case of “◯” is judged as acceptable, and otherwise it is judged as unacceptable. The results are shown in Table 2.
-Evaluation criteria-
(Metal gloss)
○: Brightness is high and the metallic luster is sufficiently visible.
(Triangle | delta): Although brightness is a little inferior, a metallic luster is visually perceived.
X: The brightness is low and the metallic luster is not visible.
(Image loss)
○: Image defect is not seen.
Δ: Some image loss is observed.
X: Many image defects are seen.

DESCRIPTION OF SYMBOLS 10 Colored particle 11 Color display layer piece 12 Structural color particle 15 Structural color particle layer 16 Periodic structure 20 Fixing layer 23 Particle image 25 Image 27 Fixing agent layer D Layer interval M Matrix P Image support

Claims (9)

  A particle image is formed on an image support with colored particles containing at least a structural color particle and a matrix and displaying a structural color and a thermoplastic resin, and the particle image is heated. An image forming method characterized in that fixing is performed by the method.   The image forming method according to claim 1, wherein the particle image is formed by an electrophotographic method.   The image forming method according to claim 1, wherein the color display layer piece has a major axis diameter of 3 to 75 μm and a minor axis diameter of 1 to 50 μm.   4. The image forming method according to claim 1, wherein a content of the color display layer piece in the colored particles is in a range of 0.1 to 50 mass%.   The structural color particles constituting the color display layer piece relating to the colored particles are made of a resin, and the glass transition temperature (Tg) of the resin constituting the structural color particles is higher than the temperature of the heat treatment. The image forming method according to claim 1, wherein the image forming method comprises:   6. The image formation according to claim 1, wherein the thermoplastic resin constituting the colored particles has a softening point temperature (Tsp) equal to or lower than the temperature of the heat treatment. Method.   The structural color particles constituting the color display layer piece relating to the colored particles are made of resin, and the matrix is air, and the heat constituting the colored particles and the resin constituting the structural color particles. The image forming method according to claim 1, wherein the plastic resin is incompatible with each other.   The material constituting the matrix constituting the color display layer piece relating to the colored particles and the thermoplastic resin constituting the colored particles are incompatible with each other. The image forming method according to claim 6. The image forming method according to claim 1, wherein a colorant is contained in a portion of the colored particles containing a thermoplastic resin.

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