JP2020071388A - Image forming method - Google Patents

Abstract

To provide means that can form an image that has improved metallic properties, such as a pearl tone and a mirror tone and prevents a powder from being easily peeled off.SOLUTION: An image forming method includes a step of softening a resin layer formed on a recording medium, and a step of supplying a powder onto the recording medium, wherein the resin layer includes at least one type of inorganic particles, and the inorganic particles have a number average primary particle diameter of 5 nm or more and 500 nm or less.SELECTED DRAWING: None

Description

  The present invention relates to an image forming method.

  In recent years, in the on-demand printing market, demand for special color printing and high value-added printing is increasing. In particular, demands for metallic printing and pearl printing are particularly great, and various kinds of studies have been conducted on a printing technique capable of imparting a texture such as a glossy feeling (for example, metallic feeling, a pearly tone).

  As one of the methods, a method of using a toner as an adhesive layer and transferring a foil such as a metal foil or a resin foil has been studied. For example, Patent Document 1 proposes a technique of forming a toner image and adhering the transfer foil only to the toner image portion. In this method, when the foil body is selectively transferred to only a part of the image, all the foil body which is not transferred is discarded, which is economically unfavorable. Further, when printing a plurality of glossy images having different glossiness such as a combination of a mirror tone and a glitter tone, it is necessary to prepare a plurality of types of foil bodies according to each texture.

  On the other hand, studies have also been conducted on a technique of adding a bright pigment to a toner. For example, Patent Document 2 proposes a technique in which toner particles containing a glitter pigment are used to impart glitter to only a necessary image portion to form an image having a metal-like texture.

  However, in the technique described in Patent Document 2, it was difficult to express a desired texture. Therefore, as a method different from each of the above methods, a technique has been proposed in which a decorative powder is attached to a resin layer formed on a recording medium to form a metal-like decorative image (Patent Document 1). 3). According to such a technique, a sufficient metallic feeling or pearly feeling can be efficiently imparted only to a necessary portion of an image.

JP-A-1-200985 JP, 2014-157249, A JP, 2013-178452, A

  However, as a result of the studies by the present inventors, in the technique described in Patent Document 3, the decorative powder is excessively embedded in the resin layer when the resin layer is softened, so that the powder surface There is a problem that the light reflection area becomes small and it is difficult to make an adjustment for finishing a metallic image into a desired mirror tone or pearl tone.

  Further, the adhesion of the decorative powder is weak, so that the image surface is roughened, and there is a problem that the surrounding image is contaminated due to the powder peeling.

  Therefore, an object of the present invention is to provide a means capable of forming a decorative image in which metallic properties such as a mirror tone and a pearl tone are improved and powder is hardly peeled off.

  The above problems of the present invention are solved by the following means.

An image forming method comprising: a step of softening a resin layer formed on a recording medium; and a step of supplying powder onto the recording medium,
The image forming method, wherein the resin layer contains at least one kind of inorganic particles, and the number average primary particle diameter of the inorganic particles is 5 nm or more and 500 nm or less.

  According to the present invention, there is provided a means capable of forming a decorative image in which metallic properties such as a mirror tone and a pearl tone are improved and powder is hardly peeled off.

It is a figure for explaining a powder supply means and an image forming method concerning one embodiment of the present invention. It is a figure for demonstrating the powder supply means and image forming method which concern on other embodiment of this invention. It is a figure for explaining the powder supply means and the image forming method concerning other embodiments of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described. The present invention is not limited to the following embodiments. Further, in the present specification, “X to Y” indicating a range includes X and Y and means “X or more and Y or less”. Further, in the present specification, unless otherwise specified, operations and measurements of physical properties and the like are performed at room temperature (20 to 25 ° C.) / Relative humidity of 40 to 50% RH.

  In addition, in this specification, "(meth) acrylic" means "acrylic and / or methacrylic".

  An image forming method according to an embodiment of the present invention is an image forming method including a step of softening a resin layer formed on a recording medium and a step of supplying powder onto the recording medium. In the image forming method, the resin layer contains at least one kind of inorganic particles, and the inorganic particles have a number average primary particle diameter of 5 nm or more and 500 nm or less. According to such an image forming method, it is possible to form a decorative image in which metallic properties such as a mirror tone and a pearl tone are improved and the powder is hardly peeled off.

  Although the details of the reason why the above-described effects are obtained by the image forming method according to an aspect of the present invention are unknown, it is considered that the mechanism is as follows. However, the following mechanism is speculative, and its correctness does not affect the technical scope of the present embodiment.

  In the present invention, the presence of the particles of 5 nm to 500 nm in the resin layer exerts a filler effect and hardens the surface portion of the resin layer. Then, since the appropriate hardness can be maintained when the resin layer is softened, it is possible to prevent the powder from being buried when the powder is decorated. As a result, the image formation is completed while keeping the powder reflection surface wide, so it is possible to form an image with improved metallicity such as a mirror tone or a pearl tone without limiting the image forming process to specific conditions. It is thought that you can do it. Inorganic particles having a number average primary particle diameter of less than 5 nm can prevent the powder from being buried because the filler effect is stronger, but the resin surface becomes too hard and the adhesion of the powder becomes weak and the resin surface Since the amount of powder adhered on the top surface is reduced, it is considered that the metallic properties such as pearly tone and mirror tone are reduced as a result. When inorganic particles having a number average primary particle diameter of more than 500 nm are used, the inorganic particles themselves impede the adhesion of the powder, so that the adhesion of the powder to the softening resin is weakened and the powder easily peels off. As a result, it is considered that the metallic properties such as pearly tone and mirror tone are deteriorated.

<Resin layer>
The resin layer is formed on the recording medium and contains a resin. In addition to the resin, the resin layer may contain other components such as a colorant, a release agent, a charge control agent, an external additive, a dispersant, a surfactant, a plasticizer, and an antioxidant. Here, “formed on a recording medium” may be formed directly on the recording medium or may be formed on the recording medium via another layer (for example, a layer having a decorative powder). It means good. Hereinafter, each component of the resin layer will be described.

[Polyester resin]
(Amorphous polyester resin)
In the image forming method of the present invention, the resin layer preferably contains an amorphous polyester resin. By containing the amorphous polyester resin, the degree of softening becomes uniform at the time of softening after forming the resin layer, and the powder adhesion state is also stabilized, which is advantageous from the viewpoint of providing metallic properties.

  Here, the amorphous polyester resin is a known polyester obtained by a polycondensation reaction between a divalent or higher carboxylic acid component (polyvalent carboxylic acid component) and a divalent or higher valent alcohol component (polyhydric alcohol component). Among the resins, it is a resin that does not have a melting point and has a relatively high glass transition temperature (Tg) when a differential scanning calorimetry (DSC) is performed. The amorphous polyester resin is not particularly limited, and a conventionally known amorphous polyester resin in this technical field can be used.

  As the polycarboxylic acid component constituting the amorphous polyester resin, it is preferable to use unsaturated aliphatic polycarboxylic acid and / or aromatic polycarboxylic acid. Note that a saturated aliphatic polycarboxylic acid may be used in combination so long as it can form an amorphous polyester resin.

  Examples of the unsaturated aliphatic polycarboxylic acid include methylene succinic acid, fumaric acid, maleic acid, 3-hexenedioic acid, 3-octenedioic acid, an alkyl group having 1 to 20 carbon atoms or 2 to 2 carbon atoms. Unsaturated aliphatic dicarboxylic acids such as succinic acid substituted with 20 alkenyl groups: 3-butene-1,2,3-tricarboxylic acid, 4-pentene-1,2,4-tricarboxylic acid, aconitic acid and the like Saturated aliphatic tricarboxylic acids; unsaturated aliphatic tetracarboxylic acids such as 4-pentene-1,2,3,4-tetracarboxylic acid, and the like, and lower alkyl esters and acid anhydrides thereof may also be used. it can. Specific examples of the succinic acid substituted with an alkyl group having 1 to 20 carbon atoms or an alkenyl group having 2 to 20 carbon atoms include dodecyl succinic acid, dodecenyl succinic acid, octenyl succinic acid, decenyl succinic acid and the like. Moreover, these lower alkyl esters and acid anhydrides can also be used. Among them, the unsaturated aliphatic polycarboxylic acid is preferably at least one of fumaric acid and dodecenylsuccinic acid from the viewpoint of further improving the effect of the present invention.

  Examples of aromatic polycarboxylic acids include phthalic acid, terephthalic acid, isophthalic acid, t-butylisophthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-phenylenediacetic acid and 2,6-naphthalenedicarboxylic acid. Aromatic dicarboxylic acids such as 4,4′-biphenyldicarboxylic acid and anthracenedicarboxylic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,3,5-benzenetricarboxylic acid (trimesic acid), 1 Aromatic tricarboxylic acids such as 2,2,4-naphthalene tricarboxylic acid and hemimellitic acid; Aromatic tetracarboxylic acids such as pyromellitic acid and 1,2,3,4-butanetetracarboxylic acid; Aromatic hexa such as mellitic acid Carboxylic acid, etc., and lower alkyl esters of these (eg, methyl Ester, can also be used ethyl ester, etc.) or an acid anhydride. Among them, from the viewpoint of further improving the effect of the present invention, the aromatic polycarboxylic acid is at least one selected from the group consisting of terephthalic acid, isophthalic acid, trimellitic acid, and lower alkyl esters and acid anhydrides thereof. Is preferred.

  Examples of the saturated aliphatic polycarboxylic acid include saturated aliphatic dicarboxylic acids among the polycarboxylic acid components listed in the section of the crystalline polyester resin described later, and among them, adipic acid is preferable.

  As the polyhydric alcohol component constituting the amorphous polyester resin, it is preferable to use an aromatic polyhydric alcohol and / or an aliphatic polyhydric alcohol.

  Examples of aromatic polyhydric alcohols include bisphenol A (2,2-bis (4-hydroxyphenyl) propane), bisphenol F (bis (4-hydroxyphenyl) methane) and 2,2-bis (4-hydroxy-). 3,5-Dimethylphenyl) propane, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxy-3,5-diphenyl) ) Butane, 2,2-bis (4-hydroxy-3,5-diethylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, and 1-phenyl-1,1-bis (4-hydroxyphenyl) ) Bisphenol compounds such as ethane and their alkylene oxide adducts, 1,3,5-benzenetriol, 2,4 benzene triol, such as 1,3,5-trihydroxy methyl benzene and the like, can also be used derivatives thereof. Among them, from the viewpoint of further improving the effects of the present invention, the aromatic polyhydric alcohol is preferably at least one selected from the group consisting of bisphenol A and alkylene oxide adducts thereof. Here, examples of the alkylene oxide adduct include an ethylene oxide adduct and a propylene oxide adduct.

  The aliphatic polyhydric alcohol may be saturated or unsaturated. Examples of the saturated aliphatic polyhydric alcohol include ethylene glycol, propylene glycol, neopentyl glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1 , 6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1, 13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol, neopentyl glycol and the like can be mentioned. Examples of the unsaturated aliphatic polyhydric alcohol include 2-butene-1,4-diol, 3-butene-1,4-diol, 2-butyne-1,4-diol, 3-butyne-1,4-. Examples include unsaturated aliphatic diols such as diol and 9-octadecene-7,12-diol. Examples of the saturated aliphatic polyhydric alcohol include glycerin, trimethylolpropane, pentaerythritol, sorbitol and the like. Furthermore, these derivatives can also be used. Among them, the aliphatic polyhydric alcohol is preferably a saturated aliphatic polyhydric alcohol, and more preferably at least one selected from the group consisting of ethylene glycol, propylene glycol, and neopentyl glycol.

  The polyhydric alcohol component may be used alone or in combination of two or more.

  A polyester resin obtained by polycondensation of a polyvalent carboxylic acid and a polyhydric alcohol is further added with a monocarboxylic acid and / or a monoalcohol to esterify the hydroxyl group and / or the carboxyl group at the polymerization end. Alternatively, the acid value of the polyester resin may be adjusted. Examples of the monocarboxylic acid include acetic acid, acetic anhydride, benzoic acid, trichloroacetic acid, trifluoroacetic acid and propionic anhydride, and examples of the monoalcohol include methanol, ethanol, propanol, octanol, 2-ethylhexanol and trifluoroethanol. , Trichloroethanol, hexafluoroisopropanol, phenol and the like.

  The method for producing the amorphous polyester resin is not particularly limited, and the resin is produced by polycondensing (esterifying) the polyvalent carboxylic acid component and the polyhydric alcohol component using a known esterification catalyst. can do.

Examples of catalysts that can be used in the production include alkali metal compounds such as sodium and lithium; compounds containing Group 2 elements such as magnesium and calcium; aluminum, zinc, manganese, antimony, titanium, tin, zirconium, germanium and the like. Examples thereof include metal compounds; phosphorous acid compounds; phosphoric acid compounds; and amine compounds. Considering availability, dibutyltin oxide, tin octylate, tin dioctylate, their salts, tetrabutoxy titanate (tetrabutyl orthotitanate, Ti (O-nBu) ₄ ), tetraisopropyl titanate (titanium tetraisopropoxy). It is preferable to use a)), tetramethyl titanate or the like. You may use these individually by 1 type or in combination of 2 or more type.

  The use ratio of the polyhydric alcohol component and the polycarboxylic acid component is the equivalent ratio ([OH]: [COOH] of the hydroxyl group [OH] of the polyhydric alcohol component and the carboxyl group [COOH] of the polyhydric carboxylic acid component. ) Is preferably 0.5: 1 to 2.5: 1.

  The temperature of polycondensation (esterification) is not particularly limited, but it is preferably 150 to 250 ° C. The polycondensation (esterification) time is not particularly limited, but is preferably 0.5 to 15 hours. During the polycondensation, the pressure inside the reaction system may be reduced if necessary.

  The lower limit of the weight average molecular weight (Mw) of the amorphous polyester resin is preferably 4,000 or more, more preferably 6,000 or more, and even more preferably 8,000 or more.

  The upper limit of the weight average molecular weight (Mw) of the amorphous polyester resin is preferably 250,000 or less, more preferably 200,000 or less, still more preferably 150,000 or less.

  In addition, in this specification, the value measured by gel permeation chromatography (GPC) shall be adopted as the weight average molecular weight (Mw) of each resin. Specifically, using an apparatus “HLC-8120GPC” (manufactured by Tosoh Corporation) and a column “TSKguardcolumn + TSKgelSuperHZ-M3 series” (manufactured by Tosoh Corporation) while maintaining the column temperature at 40 ° C., tetrahydrofuran (THF) as a carrier solvent. ) At a flow rate of 0.2 mL / min. The measurement sample (resin) is dissolved in tetrahydrofuran so that the concentration becomes 1 mg / ml. The preparation of the solution is performed by using an ultrasonic disperser for 5 minutes at room temperature. Next, a sample solution is obtained by treating with a membrane filter having a pore size of 0.2 μm, 10 μL of this sample solution is injected into the apparatus together with the above-mentioned carrier solvent, and detection is performed using a refractive index detector (RI detector). The molecular weight distribution of the measurement sample is calculated based on a calibration curve prepared using monodisperse polystyrene standard particles. Ten points are used as the polystyrene for measuring the calibration curve.

(Crystalline polyester resin)
In the image forming method according to the present invention, the resin layer preferably contains a crystalline polyester resin in addition to the amorphous polyester resin. By using the amorphous polyester resin and the crystalline polyester resin in combination, the adhesion between the resin layer and the decorated powder is further improved, and the powder peeling is further suppressed.

  The crystalline polyester resin is a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polyvalent carboxylic acid) and a divalent or higher valent alcohol (polyhydric alcohol), and differential scanning calorimetry In (DSC), it means a resin having a clear endothermic peak instead of a stepwise endothermic change. The definite endothermic peak is specifically a half-value width of the endothermic peak within 15 ° C. when measured at a temperature rising rate of 10 ° C./min in differential scanning calorimetry (DSC) described in Examples. It means the peak.

  The polyvalent carboxylic acid component and the polyhydric alcohol component constituting the crystalline polyester resin each have a valence of preferably 2 to 3, and particularly preferably 2 respectively, and thus when the valence is 2, That is, the dicarboxylic acid component and the diol component will be described.

  An aliphatic dicarboxylic acid is preferably used as the dicarboxylic acid component, and an aromatic dicarboxylic acid may be used in combination. As the aliphatic dicarboxylic acid, it is preferable to use a linear one. The use of the straight chain type has an advantage that the crystallinity is improved. The dicarboxylic acid component is not limited to one type, and two or more types may be mixed and used.

  Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid. Acid (dodecanedioic acid), 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid (tetradecanedioic acid), 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecane Examples thereof include dicarboxylic acid and 1,18-octadecanedicarboxylic acid.

  Examples of the aromatic dicarboxylic acid that can be used together with the aliphatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, t-butylisophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid and the like. Is mentioned. Among these, terephthalic acid, isophthalic acid, and t-butylisophthalic acid are preferably used from the viewpoint of easy availability and easy emulsification.

  In addition, trivalent or higher polyvalent carboxylic acids such as trimellitic acid and pyromellitic acid, and anhydrides of the above carboxylic acid compounds or alkyl esters having 1 to 3 carbon atoms can also be used.

  As the dicarboxylic acid component for forming the crystalline polyester resin, the content of the aliphatic dicarboxylic acid is preferably 50 constituent mol% or more, more preferably 70 constituent mol% or more, and further preferably 80 constituent mol% or more. And particularly preferably 100 constituent mol%. Within the above range, the crystallinity of the crystalline polyester resin can be sufficiently ensured.

  As the diol component, it is preferable to use an aliphatic diol, and if necessary, a diol other than the aliphatic diol may be contained. As the aliphatic diol, it is preferable to use a straight-chain type. The use of the straight chain type has an advantage that the crystallinity is improved. The diol components may be used alone or in combination of two or more.

  Examples of the aliphatic diol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7- Heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14- Examples thereof include tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol neopentyl glycol.

  Examples of the diol other than the aliphatic diol used as necessary include a diol having a double bond and a diol having a sulfonic acid group. Specifically, the diol having a double bond may be, for example, 1 , 4-butenediol, 2-butene-1,4-diol, 3-butene-1,6-diol, 4-butene-1,8-diol and the like. Further, trihydric or higher polyhydric alcohols such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol can be used.

  As the diol component for forming the crystalline polyester resin, the content of the aliphatic diol is preferably 50 constituent mol% or more, more preferably 70 constituent mol% or more, and further preferably 80 constituent mol%. % Or more, particularly preferably 100 constituent mol%. Within the above range, the crystallinity of the crystalline polyester resin can be secured.

  The method for producing the crystalline polyester resin is not particularly limited, and it can be produced by polycondensing (esterifying) the polyvalent carboxylic acid and the polyhydric alcohol using a known esterification catalyst.

  The catalyst that can be used in the production of the crystalline polyester resin is the same as the catalyst used in the above-mentioned method for producing the amorphous polyester resin.

  The polymerization temperature is not particularly limited, but it is preferably 150 to 250 ° C. The polymerization time is not particularly limited, but it is preferably 0.5 to 10 hours. During the polymerization, the pressure inside the reaction system may be reduced if necessary.

  The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 3,000 to 100,000, more preferably 5,000 to 50,000, and even more preferably 10,000 to 30,000. is there.

  The crystalline polyester resin preferably has a melting point (Tm) of 50 to 80 ° C. The melting point of the crystalline polyester resin indicates the temperature at the peak top of the endothermic peak, and is a value measured by differential scanning calorimetry using "Diamond DSC" (manufactured by Perkin Elmer Co., Ltd.). Specifically, 1.0 mg of a measurement sample (crystalline polyester resin) is enclosed in an aluminum pan (KIT No. B0143013), which is set in a sample holder of "Diamond DSC" at a measurement temperature of 0 to 200 ° C. The temperature control of heating-cooling-heating is performed under the measurement conditions of the temperature rising rate of 10 ° C / min and the temperature lowering rate of 10 ° C / min, and the data is analyzed based on the data in the second heating.

[Other resins]
In the image forming method of the present invention, the resin layer may contain a resin other than a polyester resin (hereinafter, also simply referred to as “other resin”), and specific examples thereof include (meth) acrylic resin, Styrene resin, styrene acrylic resin, olefin resin (including cyclic olefin resin), polycarbonate resin, polyamide resin, polyphenylene ether resin, polyphenylene sulfide resin, halogen-containing resin (polyvinyl chloride, polyvinylidene chloride, fluorine resin, etc.), polysulfone resin (Polyether sulfone, polysulfone, etc.), cellulose derivative (cellulose ester, cellulose carbamate, cellulose ether, etc.), silicone resin (polydimethylsiloxane, polymethylphenylsiloxane, etc.), polyvinyl ester Resin (polyvinyl acetate, etc.), acrylonitrile-butadiene-styrene copolymer (ABS resin), polyvinyl alcohol resin and derivatives thereof, rubber or elastomer (polybutadiene, diene rubber such as polyisoprene, styrene-butadiene copolymer, acrylonitrile) -Butadiene copolymer, acrylic rubber, urethane rubber, etc.) and the like. These can be used alone or in combination of two or more.

  The other resin may be a copolymer, and the form of the copolymer may be any of a block copolymer, a random copolymer, a graft copolymer, and an alternating copolymer.

  The content of the other resin is preferably less than 60% by mass, more preferably less than 50% by mass, even more preferably less than 40% by mass, and even more preferably, the total amount of the resin in the resin layer. Is less than 20% by mass, particularly preferably less than 10% by mass, and most preferably less than 1% by mass (lower limit: 0% by mass).

  The other resin may be a synthetic product or a commercially available product. The method for synthesizing the other resin is not particularly limited, and a known polymerization method such as a high-pressure radical polymerization method, a medium-low pressure polymerization method, a solution polymerization method, a slurry polymerization method, a bulk polymerization method, an emulsion polymerization method, or a gas phase polymerization method is used. be able to. Further, the radical polymerization initiator and catalyst used during the polymerization are not particularly limited, and examples thereof include radical polymerization initiators such as azo or diazo polymerization initiators and peroxide polymerization initiators; peroxide catalysts and Ziegler-Natta. Polymerization catalysts such as catalysts and metallocene catalysts; and the like can be used. In the case of the emulsion polymerization method, persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and water-soluble radical polymerization initiators such as hydrogen peroxide can be used. ..

  In the image forming method of the present invention, when the softening step described later is performed, the other resin is composed of (meth) acrylic resin, styrene resin and styrene acrylic resin from the viewpoint of easily controlling the surface state of the resin layer. At least one selected from the group is preferable, and styrene acrylic resin is more preferable.

(Styrene acrylic resin)
In the present specification, the styrene acrylic resin is a resin obtained by copolymerizing a styrene monomer and a (meth) acrylic acid ester monomer.

The styrene monomer includes styrene represented by a structural formula of CH ₂ ═CH—C ₆ H ₅ as well as those having a known side chain or functional group in the styrene structure. Specifically, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene. , Pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, and derivatives thereof.

The (meth) acrylic acid ester monomer has a functional group having an ester bond in the side chain. _{Specifically,} CH 2 = CHCOOR (R is an alkyl group) other acrylic acid ester monomer represented _by, methacrylic acid ester represented by _{CH 2 = C (CH 3)} COOR (R is an alkyl group) A vinyl ester compound such as a monomer is included. Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isopropyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate. , N-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, phenyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth ) Dimethylaminoethyl acrylate and derivatives thereof.

  Further, the styrene acrylic resin includes general vinyl monomers (olefins, vinyl esters, in addition to the above-mentioned copolymer formed only of styrene monomer and (meth) acrylic acid ester monomer). Copolymers formed by further using vinyl ethers, vinyl ketones, N-vinyl compounds and the like) are also included.

  In addition to styrene monomers, (meth) acrylic acid ester monomers and other general vinyl monomers, styrene acrylic resins include polyfunctional vinyl monomers and ionic dissociative groups on the side chains. Copolymers formed using vinyl monomers having (carboxyl group, sulfonic acid group, phosphoric acid group, etc.) are also included. Examples of such vinyl monomers include, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like.

  The content of the resin in the resin layer (that is, the total content of the polyester resin and other resins) is not particularly limited, but it is said that the surface of the resin layer is softened in the softening step to facilitate control of the surface state of the resin layer. From the viewpoint, it is preferably 60 to 100% by mass, and more preferably 75 to 95% by mass.

[Colorant]
Examples of the colorant that may be contained in the resin layer of the present invention include known colorants. Specifically, for example, C.I. I. Solvent Yellow 19, the same 44, the same 77, the same 79, the same 81, the same 82, the same 93, the same 98, the same 103, the same 104, the same 112, the same 162, C.I. I. Pigment Yellow 14, the same 17, the same 74, the same 93, the same 94, the same 138, the same 155, the same 180, the same 185; I. Solvent Red 1, 49, 52, 58, 63, 111, 122, C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122, 139, 144, 149, 166, 177, 178, 222; C.I. I. Pigment Blue 15: 3; carbon black such as channel black, furnace black, acetylene black, thermal black and lamp black, ferromagnetic metals such as iron, nickel and cobalt, alloys containing these ferromagnetic metals, strong such as ferrite and magnetite. Compounds of magnetic metals, Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, magnetic materials such as alloys that do not contain ferromagnetic metals such as chromium dioxide but exhibit ferromagnetism by heat treatment; titanium black, etc. Can be mentioned. The colorants may be used alone or in combination of two or more.

  The content of the colorant in the resin layer is not particularly limited as long as it does not impair the effects of the present invention, but is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the total resin in the resin layer. , More preferably 1 to 10 parts by mass, and even more preferably 2 to 9 parts by mass.

[Release agent]
The release agent that may be contained in the resin layer is not particularly limited, and known release agents can be used. Polyolefin wax such as polyethylene wax and polypropylene wax; branched hydrocarbon wax such as microcrystalline wax; long-chain hydrocarbon wax such as paraffin wax and sazol wax; distearyl ketone Dialkyl ketone waxes such as carnauba wax, montan wax, behenyl behenate (behenyl behenate), trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribe. Ester waxes such as henate, 1,18-octadecanediol distearate, tristearyl trimellitate and distearyl maleate; ethylenediamine behenylamide, trimellitic Amide wax such as preparative acid tristearyl amide include, but are not limited thereto.

  The content of the release agent in the resin layer is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 1 to 30 parts by mass with respect to 100 parts by mass of the total resin amount of the resin layer. , And more preferably 2 to 20 parts by mass.

[Charge control agent]
The charge control agent that may be contained in the resin layer is not particularly limited, and a known charge control agent can be used.

  The content of the charge control agent in the resin layer is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 0.01 to 30 parts by mass with respect to 100 parts by mass of the total resin amount in the resin layer. And more preferably 0.1 to 10 parts by mass.

[External additive]
Examples of the external additive that may be contained in the resin layer include known metal oxide particles. For example, silica particles, titania (titanium oxide) particles, bismuth oxide particles, alumina (aluminum oxide) particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, Examples thereof include tellurium oxide particles, manganese oxide particles, iron (III) oxide particles, and boron oxide particles. These may be used alone or in combination of two or more. In addition, organic particles such as homopolymers of styrene and methyl methacrylate and copolymers thereof may be used as an external additive. Further, as the external additive which may be contained in the resin layer, a lubricant may be mentioned. For example, salts of zinc, aluminum, copper, magnesium, calcium, etc. of stearic acid, salts of zinc, manganese, iron, copper, magnesium, etc. of oleic acid, zinc salts of palmitic acid, salts of zinc, copper, magnesium, calcium, etc., linoleic acid. Examples thereof include metal salts of higher fatty acids such as salts of zinc and calcium, and salts of ricinoleic acid such as zinc and calcium. The shape of these external additives is not limited. Examples thereof include spherical shape, flat shape, flat plate shape, and needle shape. The external additives may be used alone or in combination of two or more.

  The content of the external additive in the resin layer is not particularly limited as long as the effect of the present invention is not impaired, but is preferably 0.1 to 15 parts by mass with respect to 100 parts by mass of the total resin amount of the resin layer. And more preferably 1 to 5 parts by mass.

[Method of forming resin layer]
The method for forming the resin layer on the recording medium is not particularly limited. For example, it can be formed by coating the surface of a recording medium with a solution obtained by dissolving the above resin layer constituent components in a suitable solvent and drying. In this case, the resin layer can be applied by a commonly used method such as gravure coating, roll coating, blade coating, extrusion coating, dip coating, and spin coating.

  Further, the resin layer may be an image printed on a recording medium by a printing method such as an inkjet method or an electrophotographic method. The image formation by the inkjet method and the electrophotographic method can be performed by known image forming apparatuses.

  From the viewpoint that the effect of the present invention can be more easily obtained, the resin layer is preferably an image formed by an electrophotographic method. In the electrophotographic method, toner particles containing resin layer constituents are manufactured, the toner particles are attached to an electrostatic latent image pattern on the surface of a photoconductor to form a toner image, and the toner image is formed on a recording medium such as paper. Transcribe.

  Hereinafter, a method of manufacturing toner particles will be described.

(Method of manufacturing toner particles)
The method for producing toner particles (hereinafter, also simply referred to as “toner”) is not particularly limited, and kneading and pulverizing method, suspension polymerization method, emulsion aggregation method, dissolution suspension method, polyester elongation method, dispersion polymerization method, etc. are known. The method of is mentioned. Among these, it is preferable to employ the emulsion aggregation method from the viewpoints of uniformity of particle diameter, controllability of shape, and ease of forming a core-shell structure described later.

  In the emulsion aggregation method, a dispersion liquid of resin particles (hereinafter, also referred to as “resin particles”) dispersed by a surfactant or a dispersion stabilizer is mixed with a dispersion liquid of toner particle constituents such as colorant particles. In this method, toner particles are formed by adding an aggregating agent to agglomerate the toner particles until a desired toner particle diameter is obtained, and then or simultaneously with the agglomeration, resin particles are fused and shape control is performed. ..

  When the toner particles contain an internal additive, the resin particles may contain an internal additive (for example, a release agent, a colorant, etc.), or a separate internal additive (for example, a release agent). , A colorant, etc.) may be prepared, and the internal additive particles may be aggregated together when the resin particles are aggregated.

  Further, toner particles having a core-shell structure can be obtained by the emulsion aggregation method. Specifically, for toner particles having a core-shell structure, first, resin particles for a core particle and a colorant are aggregated (and fused) to prepare a core particle, and then in a dispersion liquid of the core particle. Can be obtained by adding resin particles for the shell layer to, and aggregating and fusing the resin particles for the shell layer on the surface of the core particle to form a shell layer covering the surface of the core particle.

  When the toner is produced by the emulsion aggregation method, the method for producing the toner according to the preferred embodiment is the step of (a) dispersing the resin layer constituent components (polyester resin etc.) in an aqueous medium to prepare a dispersion liquid (hereinafter, referred to as " (Also referred to as "dispersion preparing step") and (b) a step of mixing the dispersions obtained in (a) above to agglomerate and fuse the resin particles (hereinafter also referred to as "agglomeration / fusion step"). ) And, including.

  Hereinafter, each of the steps (a) and (b) and each of the steps (c) to (e) optionally performed other than these steps will be described in detail.

(A) Dispersion Liquid Preparation Step The step (a) is a polyester resin dispersion liquid preparation step, and if necessary, a dispersion liquid preparation step of another resin, a colorant dispersion liquid preparation step, and a release agent dispersion liquid preparation step. Including etc.

  The process of preparing each dispersion will be described below.

(A-1) Polyester resin dispersion liquid preparation step In the polyester resin dispersion liquid preparation step, the above polyester resin (amorphous polyester resin, crystalline polyester resin) is synthesized, and the polyester resin is dispersed in an aqueous medium. This is a step of preparing a dispersion liquid of polyester resin particles. Since the method for producing the polyester resin is as described above, the details are omitted.

  As a method for preparing the polyester resin dispersion, for example, a method of performing a dispersion treatment in an aqueous medium without using a solvent, a polyester resin is dissolved in a solvent to form a solution, and the aqueous medium is added to the solution, followed by removal. Examples include a method of performing solvent treatment. The latter method is preferred in the present invention. The solvent used in the latter method is not particularly limited, and examples thereof include isopropanol, butanol, methyl ethyl ketone and the like.

  Here, the "aqueous medium" means one containing at least 50% by mass or more of water, and examples of the components other than water include organic solvents soluble in water, such as methanol, ethanol, isopropanol, and the like. Examples thereof include butanol, acetone, dimethylformamide, methyl cellosolve, tetrahydrofuran and the like. Among these, it is preferable to use an alcohol-based organic solvent such as methanol, ethanol, isopropanol or butanol, which is an organic solvent that does not dissolve the resin. Preferably, only water is used as the aqueous medium.

  The polyester resin may contain a carboxyl group. Therefore, in order to ionically dissociate the carboxyl group and stably and smoothly emulsify the polyester resin in the water phase to smoothly promote the emulsification, ammonia, sodium hydroxide or the like may be added.

  Furthermore, a dispersion stabilizer may be dissolved in the aqueous medium, and a surfactant, resin particles and the like may be added for the purpose of improving the dispersion stability of oil droplets.

  As the dispersion stabilizer, known ones can be used, for example, it is preferable to use those soluble in an acid or an alkali such as tricalcium phosphate, or from the viewpoint of the environment, by an enzyme. It is preferable to use one that can be decomposed.

  As the surfactant, known anionic surfactants, cationic surfactants, nonionic surfactants and amphoteric surfactants can be used.

  Examples of resin particles for improving dispersion stability include polymethylmethacrylate resin particles, polystyrene resin particles, and polystyrene-acrylonitrile resin particles.

  Such dispersion treatment can be performed by utilizing mechanical energy, and the disperser is not particularly limited, and includes a homogenizer, a low speed shearing disperser, a high speed shearing disperser, and a friction disperser. Machines, high-pressure jet dispersers, ultrasonic dispersers, high-pressure impact dispersers Ultimizer, and the like.

  The average particle diameter of the polyester resin particles in the polyester resin dispersion is, as a volume-based median diameter, preferably 60 to 1000 nm, more preferably 80 to 500 nm, and even more preferably 100 to 250 nm. The volume-based median diameter (D50) is a value measured by Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.).

  The content of the polyester resin particles in the polyester resin dispersion liquid is preferably in the range of 10 to 50 mass% with respect to 100 mass% of the dispersion liquid, and more preferably in the range of 15 to 40 mass%. Within the above range, the spread of the particle size distribution can be suppressed.

(A-2) Dispersion Preparation Step of Other Resin Here, the dispersion preparation step will be described by taking a styrene-acrylic resin as an example of “other resin”.

  The styrene acrylic resin dispersion liquid preparing step is a step of synthesizing a styrene acrylic resin and dispersing the styrene acrylic resin in an aqueous medium to prepare a dispersion liquid of styrene acrylic resin particles.

  The method for dispersing the styrene acrylic resin in the aqueous medium is not particularly limited, but for example, styrene acrylic resin particles are formed from a monomer for obtaining the styrene acrylic resin, and an aqueous dispersion of the styrene acrylic resin particles is prepared. The method of preparation is preferred.

  In this method, a monomer for obtaining a styrene acrylic resin is added to a water-based medium together with a polymerization initiator for polymerization. The aqueous medium is as described in (a-1) above, and an interface of sodium dodecyl sulfate, sodium polyoxyethylene-2-dodecyl ether sulfate, or the like is added to the aqueous medium for the purpose of improving dispersion stability. Activators, resin particles and the like may be added.

  As the polymerization initiator, a water-soluble polymerization initiator can be used. As the water-soluble polymerization initiator, for example, water-soluble radical polymerization initiators such as potassium persulfate and ammonium persulfate can be preferably used.

  In this method, a commonly used chain transfer agent can be used for the purpose of adjusting the molecular weight of the styrene acrylic resin. Examples of the chain transfer agent include mercaptans such as octyl mercaptan, dodecyl mercaptan, and t-dodecyl mercaptan; mercaptopropionic acid such as n-octyl-3-mercaptopropionate and stearyl-3-mercaptopropionate; and styrene dimer. Can be used. These can be used alone or in combination of two or more.

  In the method (I), when a styrene acrylic resin particle is formed from a monomer for obtaining a styrene acrylic resin, a release agent is dispersed together with the monomer so that the styrene acrylic resin particle is separated. A mold agent may be included. Further, a dispersion liquid of styrene acrylic resin particles may be prepared by a multi-step polymerization reaction.

  The particle size of the styrene acrylic resin particles in the styrene acrylic resin dispersion is a volume-based median size, preferably 60 to 1000 nm, more preferably 80 to 500 nm, and even more preferably 100 to 250 nm. The volume-based median diameter (D50) is a value measured by Microtrac UPA-150 (manufactured by Nikkiso Co., Ltd.).

  The content of styrene acrylic resin particles in the styrene acrylic resin dispersion is preferably 5 to 50% by mass, more preferably 10 to 40% by mass. Within such a range, the spread of the particle size distribution can be suppressed.

(A-3) Colorant Dispersion Liquid Preparation Step / Release Agent Dispersion Liquid Preparation Step The colorant dispersion liquid preparation step is a step of dispersing a colorant in an aqueous medium to prepare a dispersion liquid of colorant particles. The release agent dispersion liquid preparation step is a step of dispersing a release agent in an aqueous medium to prepare a dispersion liquid of release agent particles.

  The aqueous medium is as described in (a-1) above, and a surfactant, resin particles, or the like may be added to the aqueous medium for the purpose of improving dispersion stability.

  The colorant / release agent can be dispersed by utilizing mechanical energy, and such a disperser is not particularly limited, and the disperser described in the above (a-1) is used. be able to.

(B) Aggregation / fusion step In this aggregation / fusion step, the above-mentioned polyester resin particles in the aqueous medium, and, if necessary, other resin particles, colorant particles, and release as required In this step, the agent particles are aggregated, and at the same time, these particles are fused to obtain toner base particles.

  In this step, the dispersions obtained in (a) above are mixed. Here, by adjusting the blending amount of each dispersion liquid, the content ratio of the crystalline polyester resin, the amorphous polyester resin, and the other resin can be controlled within a preferable range.

  Next, after adding an alkali metal salt, a salt containing a Group 2 element, an aluminum salt or the like as an aggregating agent, heating is performed at a temperature equal to or higher than the glass transition temperature of the resin to promote aggregation, and at the same time, the resin particles are fused to each other. Let Next, when the size of the aggregated particles reaches a target size, salt such as saline is added to stop the aggregation.

  In the aggregating step, it is important to continue the fusion by maintaining (aging) the temperature of the aggregating dispersion for a certain period of time, preferably until the volume-based median diameter becomes 4.5 to 7.0 μm. is there. Further, it is preferable to measure the average circularity of the particles during aging and perform the aging step (also referred to as a crystal aging step) until the average circularity is preferably 0.920 to 1.000.

(C) Cooling Step This cooling step is a step of cooling the dispersion liquid of the toner base particles. The cooling rate in the cooling treatment is not particularly limited, but is preferably 0.2 to 20 ° C./minute. The cooling treatment method is not particularly limited, and examples thereof include a method of cooling by introducing a refrigerant from the outside of the reaction vessel and a method of directly charging cold water into the reaction system to cool.

(D) Filtering, Washing, and Drying Steps In the filtering step, the toner base particles are filtered out from the dispersion liquid of the toner base particles. The filtration method includes, but is not particularly limited to, a centrifugation method, a vacuum filtration method using a Nutsche or the like, and a filtration method using a filter press or the like.

  Then, the toner base particles (cake-like aggregates) filtered out by washing in a washing step remove deposits such as surfactants and aggregating agents. The washing treatment is performed by washing with water until the electric conductivity of the filtrate reaches, for example, a level of 5 to 20 μS / cm.

  In the drying step, the washed toner base particles are dried. Examples of the dryer used in this drying step include known dryers such as a spray dryer, a vacuum freeze dryer, a vacuum dryer, a stationary shelf dryer, a mobile shelf dryer, a fluidized bed dryer, and a rotary dryer. It is also possible to use a dryer or a stir dryer. The amount of water contained in the dried toner base particles is preferably 5% by mass or less, and more preferably 2% by mass or less.

  Further, when the dried toner base particles are aggregated by a weak interparticle attraction force, the crushing process may be performed. As the crushing treatment device, a mechanical crushing device such as a jet mill, a Henschel mixer (registered trademark), a coffee mill, or a food processor can be used.

(E) External Additive Treatment Step This step is a step of producing toner particles by adding and mixing an external additive to the surface of the dried toner base particles as needed. The addition of the external additive improves the fluidity, charging property, cleaning property, etc. of the toner particles, so that the resin layer can be formed smoothly.

(Developer)
The toner particles obtained as described above can also be used as a magnetic or non-magnetic one-component magnetic toner. Further, it may be mixed with a carrier and used as a two-component developer.

  When a two-component developer is used, the carrier that constitutes the two-component developer is made of a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of those metals with a metal such as aluminum or lead. Magnetic particles can be used, and it is particularly preferable to use ferrite particles.

  As the carrier, a coated carrier in which the surface of magnetic particles is further coated with a coating agent such as a resin, or a dispersion type carrier in which a magnetic fine powder is dispersed in a binder resin may be used. The resin composition for coating is not particularly limited, but for example, an olefin resin, a cyclohexyl methacrylate-methyl methacrylate copolymer, a styrene resin, a styrene acrylic resin, a silicone resin, an ester resin, a fluororesin or the like is used. In addition, the resin (binder resin) for forming the dispersion type carrier is not particularly limited, and known ones can be used, and examples thereof include acrylic resin, styrene acrylic resin, polyester resin, fluororesin, and phenol resin. Can be used.

  The volume-based median diameter (volume average particle diameter) of the carrier is preferably 15 to 100 μm, more preferably 25 to 80 μm. The volume-based median diameter (d50) of the carrier can be typically measured by a laser diffraction type particle size distribution measuring device "HELOS" (manufactured by SYMPATEC) equipped with a wet dispersion machine. it can.

[Characteristics of resin layer]
The thickness of the resin layer formed on the recording medium is not particularly limited as long as the decorated powder is retained, but is, for example, 3 to 20 μm. The thickness of the resin layer may be uniform or non-uniform. As a measure of the thickness of the resin layer, for example, (if the resin layer is a toner image) when the resin layer is formed by the toner, the toner adhering amount ^is at 0.1g / ^{m 2} ~25.0g / m 2 preferably when ^there, and more preferably a ^{1.0g / m 2 ~20.0g / m 2} .

<Powder (decorative powder)>
In the image forming method according to an aspect of the present invention, the powder (decorated powder, also simply referred to as “powder” in the present specification) is appropriately selected according to the purpose of the decoration and the desired texture. be able to.

  The shape and size of the powder supplied to the resin layer are not particularly limited, and it is preferable to select an appropriate shape and size in order to achieve the desired texture.

  From the viewpoint of shape, powder is roughly classified into spherical (spherical powder) and non-spherical (non-spherical powder). Here, the “spherical powder” refers to a powder whose cross-sectional shape or projected shape has an average circularity of 0.970 or more (upper limit: 1.000). The average circularity can be obtained by a known method. For example, the average circularity can be obtained by capturing a photographic image taken by a scanning electron microscope with a scanner and analyzing the image with an image processing analysis device. Can be measured at. Specifically, it is possible to obtain the circle equivalent diameter perimeter and perimeter from the analyzed image, then determine the circularity of 50 powders according to the following formula, and average them.

  In the above equation, A represents the projected area of the powder and B represents the perimeter of the powder. The circularity is a true sphere when 1.0, and the lower the value, the higher the degree of irregular shape.

  Further, the "non-spherical powder" is a powder other than the spherical powder and has a cross-sectional shape or projected shape with an average circularity of less than 0.970. The lower limit of the average circularity of the non-spherical powder is not particularly limited, but it is preferably 0.001 or more.

  Above all, the desired texture (in particular, mirror-like and pearl-like) can be obtained by controlling the orientation of the powder, and therefore the powder is preferably non-spherical. That is, the powder preferably contains a non-spherical powder. At this time, it is preferable that the content of the non-spherical powder is large relative to the total amount of the powder. Specifically, the content of the non-spherical powder with respect to the total mass of the powder is preferably 50 to 100% by mass, and more preferably 70 to 100% by mass. From the same viewpoint, it is more preferable that the non-spherical powder contains a flat powder (that is, particles having a flat shape). At this time, it is preferable that the content of the flat powder is large relative to the total amount of the non-spherical powder. Specifically, the content of the flat powder with respect to the total mass of the non-spherical powder is preferably 50 to 100% by mass, and more preferably 70 to 100% by mass. Here, the “flat shape” or the “flat shape” means that the maximum length of the powder (particle) is the major axis L, the maximum length in the direction orthogonal to the major axis L is the minor axis 1, and the major axis L. When the minimum length in the orthogonal direction is the thickness t, it means that the ratio of the minor axis l to the thickness t (l / t) is 5 or more. The terms "flat" and "flat shape" include, for example, shapes called flakes, scales, plates, flakes, and the like.

  The average particle diameter of the powder (when the powder is a non-spherical powder, the average value of the lengths of the longest linear portions) is preferably 0.5 to 1000 μm, and 1 to 500 μm. Is more preferable and 5 to 150 μm is particularly preferable. Within the above range, the resin layer is well fixed to the resin layer, and the texture of the decorated image is also good.

  The average particle diameter of the powder is an average value of particle diameters measured for 100 powder particles. The individual particle diameter (including the long diameter and the short diameter) can be measured, for example, by observing with a scanning electron microscope. Further, as the values of the major axis, the minor axis and the thickness of the flat powder, the average value of the values measured by the above method is adopted.

  The material of the powder is not particularly limited, and various materials such as resin, glass, metal and metal oxide can be used. Above all, the powder preferably contains at least one of a metal and a metal oxide, and more preferably contains a metal. When the metal is included, the metallic appearance of the decorative image can be satisfactorily exhibited. The material constituting the decorative powder may be one kind alone, or two or more kinds. When the powder contains two or more kinds of materials, it may have a form in which they are uniformly dispersed, or a form in which one material is laminated (coated) with another material. Good. As such a form, for example, a form in which a coating film (shell) made of a metal and / or a metal oxide is laminated on a base material (core) made of a resin or glass; a group made of a metal and / or a metal oxide. Examples include, but are not limited to, a form in which a coating film (shell) made of resin, glass or the like is laminated on a material (core).

  The powder may be a synthetic product or a commercially available product. Examples of non-spherical powders are ERGI neo (Oike Imaging Co., Ltd.), Metashine (registered trademark) (Nippon Sheet Glass Co., Ltd.), Sunshine baby chrome powder, Aurora powder, Pearl powder (GG Corporation), ICEGEL. Mirror Metal Powder (TAT Co., Ltd.), Pica Ace (registered trademark) MC Shine Dust, Effect C (Kurachi Co., Ltd.), Pregel (registered trademark) Magic Powder, Mirror Series (Preampha Co., Ltd.), Bonail (registered trademark) Shine Powder ( K's Planning Co., Ltd.), ergi neo (registered trademark) (Oike Industry Co., Ltd.), UBS-0010E (manufactured by Unitika Ltd.) and the like. Further, examples of the spherical powder include high-precision Unibeads (registered trademark) (Unitika Ltd.), Finesphere (registered trademark) (manufactured by Nippon Electric Glass Co., Ltd.) and the like.

  The powder used in the image forming method of the present invention may be only one kind or a combination of two or more kinds.

<Inorganic particles>
The resin layer of the present invention contains at least one kind of inorganic particles, and the inorganic particles have a number average primary particle diameter of 5 nm or more and 500 nm or less. Particles having a number average primary particle size of less than 5 nm have a stronger filler effect and can prevent powder embedding, but the resin surface becomes too hard, resulting in weak adhesion of the powder on the resin surface. Since the amount of powder adhering decreases, the metallic property of the image deteriorates. In the case of inorganic particles having a number average primary particle diameter of more than 500 nm, the inorganic particles themselves hinder the embedding of the powder, which weakens the adhesion of the powder to the softening resin and makes it easier for the powder to peel off. The metallic property such as mirror tone is deteriorated. From the viewpoint of exhibiting the filler effect more appropriately, the number average primary particle diameter of the inorganic particles is preferably 6 nm or more and 450 nm or less, more preferably 6 nm or more and 370 nm or less, and further preferably 6 nm or more and 50 nm or less. preferable.

  Further, here, a photographic image taken by using a scanning electron microscope (SEM) "JSM-7401F" (manufactured by JEOL Ltd.) is captured by a scanner, and an image processing analysis device LUZEX AP (manufactured by NIRECO CORPORATION) is used. The inorganic particles of the photographic image are binarized. Then, the Feret diameter in the horizontal direction for 100 inorganic particles is calculated, and the average value thereof is taken as the number average primary particle diameter.

  In a preferred embodiment, the inorganic particles contain a compound derived from an element having a thermal conductivity of 20 W · mK or higher at a temperature of 300K. This thermal conductivity is higher than the thermal conductivity of the resin, and when the resin layer is heated and softened, it is possible to uniformly conduct heat to the entire resin layer. As a result, the softened state of the surface of the resin layer becomes uniform, and it is possible to prevent the state in which the powder is embedded locally during powder decoration, which leads to an improvement in the metallic property of the image and suppression of powder peeling. it is conceivable that. Examples of the element having a thermal conductivity of 20 W · mK or more at a temperature of 300 K include Si, Ti, Al, Zn, Fe, Mg, Sn, Cu, Ce, Ru, Zr, and Bi elements. From the viewpoint of easy handling, the inorganic particles are at least one selected from the group consisting of silica, titanium oxide, bismuth oxide, aluminum oxide, iron (III) oxide, tin oxide and zinc oxide. preferable. Above all, the use of silica is more preferable because peeling of the decorated powder is further suppressed while maintaining high metallicity.

  In a preferred embodiment, in the resin layer, the ratio of the amount of silicon element to the total of the amount of carbon element, the amount of oxygen element, and the amount of silicon element measured by X-ray photoelectron spectroscopy (ESCA) is as follows (1). Fulfill.

  When the silicon element amount in the resin layer measured by ESCA is 0.4 atm% to 11 atm% with respect to the total of the carbon element amount, the oxygen element amount, and the silicon element amount, the resin layer is appropriately softened. Since the hardness can be maintained, it is considered that the powder can be prevented from being buried when the powder is decorated, and the powder adhesion can be excellent. When the amount of silicon element (abundance ratio) is 0.4 atm% or more, the amount of the inorganic particles for exhibiting the filler effect is sufficient and the resin layer can be appropriately cured, so that the burying of the powder is suppressed. When the amount of silicon element (abundance ratio) is 11 atm% or less, the ratio of the inorganic particles to the resin layer is not too large and the thermal conductivity does not become excessive, so that the softening of the resin is less likely to cause burying of the powder. Further, the amount of silicon element (abundance ratio) is a number average primary particle diameter of a compound made of a silica-derived compound in the inorganic particles, the addition amount of silica particles, the addition amount of a hydrophobizing agent having a silicon atom, the amount of copolymerization monomer, It can be controlled by the amount of the crosslinking agent. The silicon element amount in the resin layer measured by ESCA is more preferably 0.5 atm% to 9.5 atm% with respect to the total of the carbon element amount, the oxygen element amount, and the silicon element amount. More preferably, it is 0 atm% to 8.0 atm%.

  In a preferred embodiment, the amount of an element having a thermal conductivity of 20 W · mK or more at a temperature of 300 K measured by X-ray photoelectron spectroscopy (ESCA) of the resin layer is X, and powder is supplied to the resin layer. When the abundance of the element exhibiting the metallic property measured by ESCA of the subsequent image is Y, the following formula (2) is satisfied.

  If the formula (2) is satisfied, it becomes easy to form an image having a more metallic property such as a mirror tone or a pearl tone. When the amount of the decorated powder is too much with respect to the amount of the inorganic particles, the filler effect of the inorganic particles is weakened and the sinking of the decorated powder into the resin layer may be increased. From the same viewpoint, X / Y ≦ 6.0 is more preferable, X / Y ≦ 3.0 is further preferable, and X / Y ≦ 1.0 is particularly preferable.

  In addition, the element exhibiting metallic property in the decorated powder refers to an element derived from a metal contained in the decorated powder, as described above. In the case of powder in which two or more metals are mixed, the amounts (abundance ratios) of two or more elements measured by ESCA are added together.

  Similarly, when there are two or more kinds of elements having a thermal conductivity of 20 W · mK or more at a temperature of 300 K, the amounts (abundance ratios) measured by ESCA are summed up.

  The inorganic particles used in the image forming method of the present invention may be only one kind or a combination of two or more kinds.

  The method for adding the inorganic particles to the resin layer is not particularly limited. For example, in the step of forming a resin layer, when printing is performed on a recording medium by an electrophotographic method, a toner layer containing a resin layer constituent component and predetermined inorganic particles as an external additive or a colorant is produced, A method of forming a resin layer containing inorganic particles by adhering the toner particles to an electrostatic latent image pattern on the surface of a photoconductor to form a toner image and transferring the toner image to a recording medium such as paper is cited. Be done.

  In addition, when a resin-containing solution is applied to form a resin layer, or when an inkjet method is used to form a resin layer, a colorant containing predetermined inorganic particles should be contained in the solution or ink. Thus, the inorganic particles can be added to the resin layer.

<Recording medium>
The recording medium used in the image forming method according to an aspect of the present invention is not particularly limited, and for example, coated printing paper such as plain paper from thin paper to thick paper, fine paper, art paper or coated paper. Paper such as commercially available Japanese paper and postcard paper; plastic films such as polypropylene (PP) film, polyethylene terephthalate (PET) film and triacetyl cellulose (TAC) film; cloth and the like. It is not limited. The color of the recording medium is not particularly limited, and various color recording media can be used.

  When the image forming method of the present invention has a softening step involving heating, the recording medium preferably has heat resistance. By using such a recording medium, the resin layer and the powder are stably held, and the durability of the obtained decorative image is improved. The term "heat resistance" means that the change in the surface state of the recording medium, the chemical change, and the physical change are small with respect to the highest surface temperature of the recording medium reached in the softening step.

<Image forming method>
The image forming method according to the present invention includes (I) a powder supply step of supplying powder onto the recording medium (hereinafter, also simply referred to as “powder supply step”), and (II) formation on the recording medium. And a softening step of softening the resin layer (hereinafter, also simply referred to as "softening step"). The (II) softening step may be performed before, after the (I) powder supplying step, or may be performed at the same time.

  In the image forming method according to an aspect of the present invention, in addition to the above-mentioned (I) powder supply step and (II) softening step, a resin layer optionally supplied with (III) decorative powder is provided from the resin layer side. It may further include a rubbing step of rubbing (hereinafter, also simply referred to as “rubbing step”).

  Hereinafter, each step will be described.

[(I) Powder supply process]
In the powder supply step, powder is supplied onto the recording medium. Here, “supplying the powder onto the recording medium” means supplying the powder directly above the recording medium or supplying the powder onto another layer (for example, a resin layer) formed on the recording medium. It means that it may be in any form. Above all, it is preferable to supply the powder onto the resin layer formed on the recording medium in the powder supplying step, since a good texture can be expressed by using a small amount of the powder.

  In the powder supply step, powder is supplied onto the recording medium. The powder supply method is not particularly limited. As the powder supplying means used in the powder supplying step, a known device can be used depending on the properties of the powder. For example, the powder supply means described in JP2013-178452A can be used as the powder supply means according to the present invention. Further, the powder supply device according to one embodiment of the present invention may be a powder supply device 10 including a powder container 11 and a powder supply roller 12 as shown in FIGS. 1 to 3.

  The amount of powder supplied to the recording medium is not particularly limited, and is not particularly limited as long as the desired texture can be expressed.

  When the powder is supplied onto the resin layer formed on the recording medium, the powder may be selectively supplied only to the portion where the resin layer is formed, or the portion where the resin layer is formed. Not only may it be supplied to the entire surface of the recording medium, including the portion where the resin layer is not formed. Further, the powder may be supplied to a part of the surface of the resin layer or may be supplied to the entire surface of the resin layer.

[(II) Softening step]
The softening step may be performed before the (I) powder supplying step, may be performed after the (I) powder supplying step, or may be performed simultaneously with the (I) powder supplying step. You may break. In the softening step, the resin layer is softened (melted) by, for example, heating the resin layer or irradiating the resin layer with light. Above all, it is preferable that the softening step includes heating the resin layer because the entire resin layer can be uniformly softened and the work is easy.

  From the viewpoint of energy saving, the upper limit of the heating temperature of the resin layer is preferably 100 ° C or lower, more preferably 90 ° C or lower, and even more preferably 85 ° C or lower. Moreover, the lower limit of the heating temperature of the resin layer is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, and even more preferably 60 ° C. or higher, from the viewpoint of quickly softening the resin layer. The heating time of the resin layer is not particularly limited, but is preferably about 10 seconds to 5 minutes from the viewpoint of moderately softening the resin layer.

  The heating means used in the softening step is not particularly limited, and a known device can be used. As shown in FIGS. 1 to 3, a heating device 20 as a heating device according to an embodiment of the present invention is provided in front of a powder supply device (powder supply device) 10 with respect to a recording medium conveyance direction. It may be provided, or may be provided after the powder supply device (powder supply means) 10. The arrangement order of these devices is appropriately determined according to the order of performing the (I) powder supply step and the (II) softening step. Further, by using an apparatus equipped with equipment capable of simultaneously supplying and heating powder, (I) powder supplying step and (II) softening step can be carried out simultaneously.

  The heating device 20 (hereinafter, also referred to as “heat source”) as a heating means may be any device that can heat the resin layer to the extent that it softens, and examples thereof include an infrared lamp, a hot plate, a nichrome wire, and hot air.

  In the softening step, the arrangement of the heating means, the recording medium and the resin layer is not particularly limited. That is, for example, in FIGS. 1 to 3, the heating device 20 is arranged on the side of the recording medium 1 opposite to the side on which the resin layer 2 is formed, but on the side of the recording medium on which the resin layer is formed. A heating device may be arranged.

  The heating may be performed while the recording medium on which the resin layer is formed is allowed to stand, or while the recording medium is moved. As a method of heating the recording medium while moving it, for example, a method of heating the recording medium while moving it by a conveying means such as a belt conveyor can be mentioned. At this time, the moving (conveying) speed of the recording medium is not particularly limited. It can be set as appropriate in consideration of productivity and ease of obtaining a desired texture.

[(III) Rubbing process]
In the image forming method according to an aspect of the present invention, after the (I) powder supply step and the (II) softening step, the resin layer to which the decorative powder is supplied is rubbed from the resin layer side. It is preferable to include a rubbing step. By performing the rubbing step, the adhesiveness between the powder and the resin layer is improved and the powder is less likely to peel off, so that the image durability and the environmental durability are improved. Also, excess powder can be removed. Furthermore, since the orientation state of the powder with respect to the resin layer can be made uniform and the in-plane gloss can be made uniform, a high metallic feeling can be obtained. Here, the "rubbing" means that the rubbing means (rubbing member) moves along the surface of the resin layer on the recording medium relative to the resin layer while contacting the surface of the resin layer. Say. Further, it is preferable that the step of rubbing the resin image supplied with the powder from the resin layer side includes rubbing by a relative speed difference between the recording medium and the rubbing member.

  Moreover, it is preferable that the above-mentioned "rubbing" is accompanied by pressing of the resin layer (the resin layer to which the decorative powder is attached). That is, the rubbing step preferably includes rubbing and pressing the resin layer to which the powder is supplied. By pressing the resin layer, a part of the powder is pushed into the resin layer, so that the adhesion of the powder to the resin layer can be strengthened. Therefore, the strength of the finally formed gloss image can be improved, and the desired appearance such as a mirror tone or a pearl tone in the formed gloss image can be made clear. Here, “pressing” means pressing the surface of the resin layer in a direction intersecting with the surface of the resin layer (for example, a vertical direction).

  The rubbing step is performed by rubbing the resin layer to which the powder adheres with a rubbing means. Specifically, in the rubbing step, a rubbing member as a rubbing means is brought into contact with the resin layer to which the decorative powder is attached, and the rubbing member is moved relative to the resin layer. By At this time, the direction in which the rubbing member is moved is not particularly limited, and may be only one direction, reciprocating motion, or more directions. However, from the viewpoint of easily controlling the orientation of the powder and forming a texture such as a mirror tone or a pearl tone with less irregular reflection, it is preferable that the sliding member moves in only one direction.

  When pressing is performed together with rubbing, the pressing force is not particularly limited, but is preferably 1 to 30 kPa with respect to the surface of the resin layer. When it is 1 kPa or more, the adhesion strength of the powder to the resin layer can be sufficiently obtained, and the image durability becomes good. Further, when it is 30 kPa or less, the resin layer formed on the recording medium can be stably held, and the image durability is improved.

  The rubbing means used in the rubbing step is not particularly limited, and a known device can be used. As shown in FIGS. 2 to 3, a rubbing member 30 as a rubbing means according to an embodiment of the present invention is provided with a powder feeding device (powder feeding means) 10 in the conveyance direction of the recording medium. It may be provided after or after the heating device (heating means) 20. The arrangement order of these devices is appropriately determined according to the order in which each process is performed.

  The rubbing member provided in the rubbing means may be, for example, a rotating member as shown in FIGS. 2 to 3, or a non-rotating member such as a reciprocating member or a fixed member. It may be. More specifically, the rubbing member may be a member that is in contact with the surface of the resin layer having a horizontal surface and is movable in the horizontal direction relative to the surface, or the surface of the resin layer. It may be a rotatable roller (rotating roller) in contact with. Among them, from the viewpoint of work efficiency, the rubbing member is preferably a rotating member, and more preferably a rotatable roller (rotating roller).

  It is preferable that the surface of the rubbing member is configured to be movable relative to the surface of the resin layer while pressing the resin layer. When the rubbing member presses, for example, the conveyed recording medium (recording medium on which the resin layer is formed) may be pressed by the fixed rubbing member. Alternatively, the pressing may be performed by rubbing with a roller that rotates in the same direction as the recording medium conveyance direction and that rotates at a slower speed than the recording medium conveyance speed, or the recording medium may be pressed. It may be carried out by rubbing with a roller that rotates in a direction opposite to the conveying direction of the recording medium, or a rotatable roller arranged such that its rotation axis is oblique to the conveying direction of the recording medium. The pressing may be performed by rubbing with, or the pressing may be performed by rubbing with a member that reciprocates on the surface of the resin layer.

  Therefore, it is preferable that the rubbing member is configured to be movable in different directions relative to the recording medium while pressing the surface of the resin layer.

  Moreover, it is preferable that the rubbing member has flexibility. The flexibility of the rubbing member is preferably, for example, such that the surface of the rubbing member is deformed to the extent that it can follow the shape of the surface of the resin layer during rubbing. That is, it is preferable that the rubbing member has deformation followability. Examples of such a flexible rubbing member include, but are not limited to, sponges and brushes.

  The image forming method according to an aspect of the present invention includes, for example, a resin layer forming step and a powder removing step in addition to the above (I) powder supplying step, (II) softening step and optionally (III) rubbing step. It may include a step such as an additional printing step.

[Resin layer forming step]
The image forming method according to an aspect of the present invention may further include a resin layer forming step before the (I) powder supplying step and the (II) softening step.

  In the resin layer forming step, a resin layer is formed on the recording medium. The method for forming the resin layer is as described above.

  Further, in the image forming method according to an aspect of the present invention, the resin layer may be an image before being fixed on a recording medium (unfixed image) or a fixed image (fixed image). It may be. From the viewpoint of easily disposing the powder on the surface of the resin layer and easily forming an image having sufficient glossiness, the resin layer is preferably a fixed image fixed on the recording medium. That is, it is preferable that the image forming method according to an aspect of the present invention further includes a fixed image forming step before the (I) powder supplying step and the (II) softening step. Since the surface of the fixed image is uniformly smoothed, the embedding of the decorative powder in the resin layer is suppressed, and a decorative image having a good texture can be obtained. In addition, since it is possible to arrange the decorative powder on the surface of the resin layer while suppressing the embedding of the decorative powder, it is not necessary to use a large amount of the decorative powder, which is also preferable from the economical point of view. ..

  The fixed image forming step can be performed by a known fixed image forming apparatus, particularly an image forming apparatus using an electrophotographic system. As an example of a fixed image forming method, a method of applying heat and pressure to a recording medium onto which a toner image has been transferred by a fixing unit to fix the toner image on the recording medium onto the recording medium can be adopted. By carrying out the image forming method according to one embodiment of the present invention using the toner image formed by the method as the resin layer, as described above, it is possible to suppress the embedding of the decorative powder in the resin layer and to improve the texture. A good decorative image can be obtained.

[Powder removal process]
The image forming method according to an aspect of the present invention further includes a powder removing step after the (I) powder supplying step and the (II) softening step, and optionally after the (III) rubbing step. May be included. In the powder removing step, the decorative powder that has not adhered to the resin layer is removed from the recording medium. At this time, the decorative powder removed from the recording medium may be collected and reused. That is, in the image forming method according to an aspect of the present invention, after the (I) powder supplying step and the (II) softening step, or (III) a rubbing step that is performed as necessary, the toner is attached to the resin layer. The method may further include a powder collecting step of collecting the undecorated decorated powder from the recording medium. In this way, it is preferable to collect the extra decorative powder that has not been used for decoration, from the viewpoint of economy and reduction of environmental load.

  The method for removing or collecting the decorated powder is not particularly limited, and a known method can be used. For example, a method of scraping with a member such as a brush or a brush, a method of removing with an adhesive member such as an adhesive tape, a method of sucking with a known device such as a dust collector capable of sucking or adsorbing powder can be cited. .. As described above, as the powder removing means (member) or the powder collecting means (member) for performing the powder removing or collecting step, as described above, a member such as a brush or a brush, or a powder is used. An adhesive member having adhesiveness, a dust collector having a suction member for sucking powder, or the like can be used. When the powder is magnetic powder, a dust collector having a magnet member may be used.

[Overprint printing process]
The image forming method according to an aspect of the present invention includes (I) a powder supplying step and (II) a softening step, and (III) a rubbing step and / or a powder removing step, which are performed as necessary. The additional printing process may be further included. In the additional printing process, an image is further formed on the recording medium having the resin layer to which the powder adheres (that is, the powder decoration image). The overprinting method is not particularly limited, and a known method can be used, for example, a printing method such as an inkjet method or an electrophotographic method can be used. A known device can be used as the additional printing means for performing the additional printing process. It is useful because the printed matter having various added values can be obtained and the various needs can be satisfied by further including the additional printing process.

[Order of each process]
The image forming method according to an aspect of the present invention includes (I) a powder supplying step and (II) a softening step, and the order of each of these steps is not particularly limited. That is, the (II) softening step may be performed before or after the (I) powder supplying step, or may be performed simultaneously.

(Image forming method of performing (II) softening step after (I) powder supplying step)
In the image forming method according to an aspect of the present invention, (II) the softening step may be performed after the (I) powder supplying step. (II) When the powder is supplied onto the resin layer after the resin layer is softened by the softening step, the resin layer is cured and the powder adheres to the resin layer between the softening of the resin layer and the supply of the powder. It may be difficult to do. Therefore, when the (II) softening step is performed first, it is necessary to raise the heating temperature of the resin layer. On the other hand, by performing (I) the powder supplying step first, the powder is heated on the resin layer and the resin layer is softened, so that the heating can be minimized. Further, since the decorated portion can be formed even if the time from the powder supplying step (I) to the softening step (II) becomes long, it is not necessary to increase the process speed. Therefore, from the viewpoint of energy efficiency, it is preferable to perform each step in the above order.

(Image forming method of performing (I) powder supply step after (II) softening step)
In the image forming method according to an aspect of the present invention, (I) the powder supplying step may be performed after the (II) softening step. When the powder is placed on the resin layer and heated, heat may be diffused by the powder. On the other hand, by performing the (II) softening step first, such heat diffusion can be suppressed, and the end portion of the portion to which gloss is imparted can be formed more clearly. That is, it is possible to sharply form the edge of the portion to which gloss is applied.

(Image forming method of simultaneously performing (I) powder supply step and (II) softening step)
In the image forming method according to an aspect of the present invention, (I) powder supplying step and (II) softening step may be performed simultaneously. Specifically, a method of heating the resin layer at a position where the decorative powder is supplied at least while the powder is being supplied may be used. In this embodiment, the (II) softening step may be performed at least during the (I) powder supplying step, and for example, the (II) softening step may be performed immediately before the (I) powder supplying step is started. May be started, and (II) the softening step is ended when (I) the powder supply step is ended. Further, the (II) softening step may be ended immediately after the (I) powder supplying step.

  In this way, by adopting a mode in which (I) powder supply step and (II) softening step are performed simultaneously, energy (heat) loss can be reduced, and the edge of the portion to which gloss is imparted is sharply formed. There is an advantage that can be done.

(Preferred form)
As described above, in the image forming method according to the present invention, it is preferable to further perform (III) a rubbing step after the steps (I) and (II). Therefore, a preferable mode of the image forming method according to the present invention includes performing (I) powder supplying step, (II) softening step, (III) rubbing step, and these steps in this order. Further, another preferable mode of the image forming method according to the present invention includes performing (II) a softening step, (I) a powder supplying step, and (III) a rubbing step in this order. Furthermore, another preferable mode of the image forming method according to the present invention is that after performing (I) powder supply step and (II) softening step at the same time, (III) rubbing step is further performed. Including.

  Further, as described above, it is preferable to perform the resin layer forming step before these steps (I) to (III), and it is preferable that the resin layer forming step is a fixed image forming step. That is, as a preferable mode of the image forming method according to the present invention, the fixed image forming step, (I) powder supplying step, (II) softening step, and (III) rubbing step are performed in this order. including. Further, another preferable embodiment of the image forming method according to the present invention comprises a fixed image forming step, (II) softening step, (I) powder supplying step, and (III) rubbing step in this order. Including doing. Further, another preferable mode of the image forming method according to the present invention is that after the fixing image forming step, (I) powder supplying step and (II) softening step are performed at the same time, and then (III) sliding The method further includes performing a rubbing step.

  Further, as described above, after the steps (I) to (III), a powder removing step (preferably a powder collecting step) and / or a reprint printing step may be further performed.

<Image forming device>
An image forming apparatus for performing an image forming method according to an aspect of the present invention includes a powder supply unit that supplies powder onto a recording medium, and a heating unit that heats a resin layer formed on the recording medium. It is preferable to have. Further, the image forming apparatus for performing the image forming method according to an aspect of the present invention may include a powder supply and heating unit that supplies and heats the powder onto the recording medium. Further, the image forming apparatus includes a rubbing means for rubbing the resin layer to which the powder has been supplied (the resin layer to which the powder has adhered), and the powder which has not adhered to the resin layer to the recording medium, if necessary. An image is further formed on a recording medium having a powder removing means (preferably a powder collecting means) to be removed from above and a resin layer to which the powder is attached (that is, a gloss image which has already been decorated). It is preferable to further include an image forming unit (additional printing unit) for performing. These rubbing means, powder removing means (preferably powder collecting means), and image forming means (overprinting printing means) may be provided alone or in combination of two or more in the image forming apparatus. Above all, it is preferable that the image forming apparatus further includes the image forming unit (overprinting printing unit) from the viewpoint of enhancing productivity of an image having high added value.

  The detailed description of the powder supplying means, heating means, rubbing means, powder removing means (powder collecting means), image forming means (overprinting printing means), etc. will be made in connection with the above steps. As described in.

  The above-mentioned image forming apparatus may be provided in the same housing as the above-mentioned housing in which the fixed image forming apparatus is installed, or may be installed outside the housing in which the fixed image forming apparatus is installed. It may be.

  The effects of the present invention will be described using the following examples and comparative examples. In the following examples, "parts" and "%" mean "parts by mass" and "% by mass", respectively, unless otherwise specified. The present invention is not limited to the examples below.

<Preparation of resin particle dispersion liquid 1 for core particles>
(First stage polymerization)
A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device was charged with 8 parts by mass of sodium lauryl sulfate and 3000 parts by mass of ion-exchanged water, and stirred while stirring at a stirring speed of 230 rpm under a nitrogen stream. The temperature was raised to 80 ° C. After the temperature was raised, a solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added, the liquid temperature was again set to 80 ° C., and a mixed liquid of the following monomers was added dropwise over 1 hour.
Styrene 540 parts by mass n-Butyl acrylate 270 parts by mass Methacrylic acid 65 parts by mass n-octyl mercaptan 17 parts by mass After dropping the above mixed solution, the monomer is polymerized by heating and stirring at 80 ° C. for 2 hours, A resin particle dispersion liquid (a-1) was prepared.

(Second-stage polymerization)
A solution prepared by dissolving 7 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate in 3000 parts by mass of ion-exchanged water was charged into a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device. Heated to ° C. After heating, 80 parts by mass of the resin particle dispersion liquid (a-1) prepared by the above first-stage polymerization in terms of solid content, and the following monomer, chain transfer agent and release agent were dissolved at 90 ° C. And the mixture.

Styrene 285.0 parts by mass n-Butyl acrylate 65.0 parts by mass Methacrylic acid 20.0 parts by mass n-octyl-3-mercaptopropionate (chain transfer agent) 2.0 parts by mass Behenyl behenate (release agent, Melting point 73 ° C) 151.0 parts by mass.

  A mechanical disperser CLEARMIX (registered trademark) (manufactured by M Technique Co., Ltd.) having a circulation path was subjected to a mixing and dispersing treatment for 1 hour to prepare a dispersion liquid containing emulsified particles (oil droplets). To this dispersion was added a solution of a polymerization initiator in which 6 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water, and the system was heated and stirred at 84 ° C. for 1 hour to carry out polymerization. A resin particle dispersion liquid (b-1) was prepared.

(Third stage polymerization)
400 parts by mass of ion-exchanged water was further added to the resin particle dispersion liquid (b-1) obtained by the second-stage polymerization and well mixed, and then 11 parts by mass of potassium persulfate was dissolved in 400 parts by mass of ion-exchanged water. The allowed solution was added. Furthermore, under a temperature condition of 82 ° C., a mixed liquid of the following monomer and chain transfer agent was added dropwise over 1 hour.

Styrene 450 parts by mass 2-ethylhexyl acrylate 140 parts by mass Methacrylic acid 52.0 parts by mass n-octyl-3-mercaptopropionate 8.0 parts by mass.

  After completion of the dropwise addition, polymerization was carried out by heating and stirring for 2 hours and then cooled to 28 ° C. to prepare resin particle dispersion liquid 1 for core particles. The weight average molecular weight (Mw) of the resin in the dispersion was 30,000. The resin particles in the dispersion had a volume-based median diameter of 205 nm.

<Synthesis of crystalline polyester resin and preparation of dispersion C1 thereof>
(Synthesis of crystalline polyester resin)
A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe and a nitrogen introducing device was charged with 281 parts by mass of tetradecanedioic acid and 206 parts by mass of 1,6-hexanediol, and the system was stirred for 1 hour. The internal temperature was raised to 190 ° C. After confirming that the catalyst was uniformly stirred, Ti (O-nBu) ₄ as a catalyst was added in an amount of 0.003 mass% with respect to 100 mass% of tetradecanedioic acid charged.

  Then, while distilling off the produced water, the internal temperature is raised from 190 ° C. to 240 ° C. over 6 hours, and the dehydration condensation reaction is continued for 6 hours under the condition of the temperature of 240 ° C. to carry out polymerization. As a result, a crystalline polyester resin was obtained. The obtained crystalline polyester resin had an acid value of 20.9, a weight average molecular weight (Mw) of 25,200, a melting point (Tm) of 74.9 ° C, and a recrystallization temperature (Rc) of 69.7 ° C. It was

(Preparation of Crystalline Polyester Resin Particle Dispersion C1)
Next, 100 parts by mass of the obtained crystalline polyester resin was dissolved in 400 parts by mass of methyl ethyl ketone and mixed with 638 parts by mass of a 0.26% by mass concentration sodium lauryl sulfate solution prepared in advance. While stirring the mixed solution, ultrasonic dispersion treatment was performed with an ultrasonic homogenizer US-150T (manufactured by Nippon Seiki Seisakusho Co., Ltd.) at V-LEVEL 300 μA for 30 minutes.

  Then, in a state of being heated to 40 ° C., a diaphragm vacuum pump V-700 (manufactured by BUCHI) was used to completely remove methyl ethyl ketone while stirring under reduced pressure for 3 hours to obtain a crystalline polyester resin particle dispersion liquid. Prepared. The crystalline polyester resin particles in the dispersion had a volume-based median diameter of 160 nm.

<Synthesis of amorphous polyester resin for shell layer and preparation of dispersion S1 thereof>
(Synthesis of amorphous polyester resin for shell layer)
A mixture of a monomer having a substituent capable of reacting with any of the following styrene acrylic resin monomers, amorphous polyester resins and styrene acrylic resins, and a polymerization initiator was placed in a dropping funnel.

Styrene 80.0 parts by mass n-Butyl acrylate 19.0 parts by mass Acrylic acid 12.0 parts by mass Di-t-butyl peroxide (polymerization initiator) 16.0 parts by mass In addition, a unit amount of the following amorphous polyester resin The body was placed in a four-necked flask equipped with a nitrogen introduction tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170 ° C. to dissolve it.

Bisphenol A Propylene oxide 2 mol adduct 285.7 parts by mass Terephthalic acid 66.9 parts by mass Fumaric acid 47.4 parts by mass With stirring, the mixed solution placed in the dropping funnel was added dropwise to the four-necked flask over 90 minutes. After aging for 60 minutes, unreacted monomers were removed under reduced pressure (8 kPa).

Then, 0.4 parts by mass of titanium tetrabutoxide (Ti (n-OBu) ₄ ) was added as an esterification catalyst, the temperature was raised to 235 ° C, and the pressure was further reduced under normal pressure (101.3 kPa) for 5 hours. The reaction was carried out at a lower temperature (8 kPa) for 1 hour.

  Then, the mixture was cooled to 200 ° C., reacted under reduced pressure (20 kPa), and then desolvated to obtain a hybrid amorphous polyester resin for shell.

(Preparation of Amorphous Polyester Resin Particle Dispersion S1 for Shell Layer)
72 parts by mass of the shell layer amorphous polyester resin obtained above was stirred and dissolved in 72 parts by mass of methyl ethyl ketone at 70 ° C. for 30 minutes. Next, to this solution, 3.0 parts by mass of a 25% by mass aqueous sodium hydroxide solution was added. This solution was placed in a reaction vessel having a stirrer, and 252 parts by mass of water warmed to 70 ° C. was added dropwise to the mixture over 70 minutes while stirring. The liquid in the container became cloudy during the dropping, and a uniform emulsified state was obtained after the entire amount was dropped.

  Then, while keeping this emulsion at 70 ° C., a diaphragm vacuum pump “V-700” (manufactured by BUCHI) was used to stir for 3 hours under reduced pressure at 15 kPa (150 mbar) to distill away methyl ethyl ketone. An aqueous dispersion S1 of an amorphous polyester resin was prepared. As a result of measurement with the above particle size distribution analyzer, the particles contained in the above dispersion had a volume average particle diameter of 92 nm.

<Preparation of colorant particle dispersion>
While stirring a solution prepared by adding 90 parts by mass of sodium lauryl sulfate to 1600 parts by mass of ion-exchanged water, 420 parts by mass of copper phthalocyanine (CI Pigment Blue 15: 3) was gradually added. A colorant particle dispersion liquid was prepared by performing a dispersion treatment using a stirrer Clearmix (registered trademark) (manufactured by M Technique Co., Ltd.). The colorant particles in the dispersion had a volume-based median diameter of 110 nm.

(Production of Toner 1)
In a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling pipe, 300 parts by mass of a resin particle dispersion liquid 1 for core particles (solid content conversion) and 1% by mass of dodecyldiphenyl ether disulfonic acid sodium salt in resin ratio (solid content conversion). And 2000 parts by mass of ion-exchanged water were added. The pH was adjusted to 10 by adding 5 mol / L sodium hydroxide aqueous solution at room temperature (25 ° C.). Further, 30 parts by mass of the colorant particle dispersion (solid content conversion) was added, and a solution of 60 parts by mass of magnesium chloride dissolved in 60 parts by mass of ion-exchanged water was added under stirring at 30 ° C. for 10 minutes. .. After standing for 3 minutes, the temperature was raised to 80 ° C. over 60 minutes, and after the liquid temperature reached 80 ° C., 22 parts by mass of crystalline polyester resin particle dispersion C1 (solid content conversion) was added over 20 minutes. Thereafter, the stirring speed was adjusted so that the growth rate of the particle diameter was 0.01 μm / min, and the volume-based median diameter measured by Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.) was grown to 6.0 μm. Let

  Then, 37 parts by mass of the amorphous polyester resin particle dispersion S1 for shell layer (solid content conversion) was added over 30 minutes, and when the supernatant of the dispersion (reaction liquid) became transparent, 190 parts of sodium chloride was added. An aqueous solution having 760 parts by mass of ion-exchanged water dissolved therein was added to stop the growth of the particle size.

  Further, by heating and stirring in a state of 80 ° C., the fusion of particles is promoted, and the average circularity is 0.970 by using a toner average circularity measuring device “FPIA-3000” (manufactured by Sysmex). Then, the temperature was lowered to 30 ° C. at a cooling rate of 2.5 ° C./min.

  Next, solid-liquid separation and dehydration of the toner cake are redispersed in ion-exchanged water and solid-liquid separation is repeated three times, and after washing, toner particles are obtained by drying at 40 ° C. for 24 hours.

  To 100 parts by mass of the obtained toner particles, 1.4 parts by mass of hydrophobic silica particles (number average primary particle size: 500 nm, hydrophobicity: 94) as an external additive were added, and a Henschel mixer (Mitsui Miike Kakoki Co., Ltd.) was added. Mixing) for 15 minutes at 32 ° C. at a rotor blade peripheral speed of 35 mm / sec. After mixing, coarse particles were removed using a sieve with an opening of 45 μm to obtain Toner 1. The volume-based median diameter of the toner 1 was 5.9 μm.

(Production of Toners 2 to 13)
Toners 1 to 13 were produced in the same manner as Toner 1 except that the particle diameter of the hydrophobic silica particles as the external additive was changed as shown in Table 1 below in the production of Toner 1.

(Production of Toner 14)
Toner 14 was prepared in the same manner as Toner 1 except that titanium oxide particles (number average primary particle diameter: 20 nm, degree of hydrophobicity: 84) were used as external additives instead of hydrophobic silica particles in the production of Toner 1. Was manufactured.

(Production of Toner 15)
Toner 15 was manufactured in the same manner as Toner 1 except that titanium oxide particles (number average primary particle diameter: 9 nm, hydrophobicity: 84) were used as the external additive instead of hydrophobic silica particles in the production of Toner 1. Was manufactured.

(Production of Toner 16)
Toner 16 was produced in the same manner as Toner 1 except that bismuth oxide particles (number average primary particle diameter: 13 nm) were used as the external additive in place of the hydrophobic silica particles in the production of Toner 1.

(Production of Toner 17)
In the production of Toner 1, except that hydrophobic silica particles having a number average primary particle diameter of 20 nm were used as an external additive and the addition amount was changed to 2.2 parts by mass with respect to 100 parts by mass of the toner particles. Toner 17 was manufactured in the same manner as Toner 1.

(Production of Toner 18)
Toner 1 was manufactured except that the addition amount of hydrophobic silica particles (number average primary particle diameter: 20 nm) as an external additive was changed to 3.5 parts by mass with respect to 100 parts by mass of toner particles. Toner 18 was manufactured in the same manner as in.

(Production of Toner 19)
In the production of Toner 1, except that the addition amount of hydrophobic silica particles (number average primary particle diameter: 20 nm) as an external additive was changed to 4.2 parts by mass with respect to 100 parts by mass of the toner particles, Toner 1 Toner 19 was manufactured in the same manner as in.

(Production of Toner 20)
In the production of Toner 1, except that the addition amount of hydrophobic silica particles (number average primary particle diameter: 20 nm), which is an external additive, was changed to 11.3 parts by mass with respect to 100 parts by mass of the toner particles, Toner 1 Toner 20 was manufactured in the same manner as in.

(Production of Toners 21 to 26)
Toner 1 to Toner 26 were produced in the same manner as Toner 1 except that the two types of inorganic particles shown in Table 1 were used as the external additives in the production of Toner 1.

(Production of Toners 27 to 29)
In the production of Toner 1, the toners 27 to 29 are the same as Toner 17, except that the addition amount of the hydrophobic silica particles (number average primary particle diameter: 20 nm) as the external additive is changed as shown in Table 1. Was manufactured.

(Production of Toner 30)
Toner 30 was produced in the same manner as Toner 1, except that the external additive was not used in the production of Toner 1.

(Production of Toners 31 to 33)
Toners 31 to 33 were manufactured in the same manner as Toner 1 except that the particle diameter of the hydrophobic silica particles as the external additive was changed as shown in Table 1 below in the manufacture of Toner 1.

(Production of toners 34 and 35)
Toners 34 and 35 were prepared in the same manner as Toner 1 except that the type of the external additive was changed to magnesium stearate (MgSt) and calcium stearate (CaSt) as shown in Table 1 in the production of Toner 1. Manufactured.

<Preparation of developer>
Ferrite carrier particles having a volume average particle diameter of 40 μm, the surface of which is coated with a copolymer of methyl methacrylate and cyclohexyl methacrylate, are mixed with the toner particles in an amount such that the toner concentration is 6% by mass, and a developer is prepared. It was made.

<Image formation>
A developer and a recording medium (OK Top Coated Paper (157 g / m ² ) manufactured by Oji Paper Co., Ltd.) are accommodated in a modified machine of “AccurioPress C2060” (manufactured by Konica Minolta Co., Ltd., “AccurioPress” is a registered trademark of the same company). A 2 cm × 2 cm square patch image (8 g / m ² ) was formed on a recording medium using a modified machine, and a toner image (resin image) having the patch image was output on the recording medium.

  The recording medium on which a resin image was formed was placed on a hot plate heated to 80 ° C. with the patch image facing upward, and on the patch image, as a powder, ergi neo (manufactured by Oike Imaging Corporation). , Average particle diameter 55 μm) was sprayed in a prescribed amount, and the surface of the patch image of the resin image was rubbed with a sponge roller for 25 seconds. The rubbing direction is limited to one direction for the experimenter, and the pressing force is about 10 kPa. Further, the powder rubbed at this time was flat, and the ratio (1 / t) of the minimum length (minor diameter) in the direction orthogonal to the major axis L to the thickness of the powder was 10. .. After the rubbing, the resin image was cooled under room temperature conditions, and the remaining powder was removed from the surface of the patch image by a brush. The portion of the patch image (final image) in the resin image thus obtained exhibited a metallic image. For Examples 1 to 26 and 28 to 35 below, 0.3 g of the powder was applied, and for Example 27, 0.02 g of the powder was applied.

  In addition, each component used in each example and comparative example is collectively shown in Table 2.

<Measurement and evaluation>
(Elemental analysis of resin image surface by X-ray photoelectron spectroscopy analysis (ESCA))
The amount (abundance ratio) of silicon element on the resin image surface in each of Examples and Comparative Examples was determined as follows.

  The amount (abundance ratio) of the silicon element on the resin image surface was determined by using an X-ray photoelectron spectroscopy analyzer "K-Alpha" (manufactured by Thermo Fisher Scientific) under the following conditions. Was carried out, and the relative ratio of the atomic peak area was used to calculate the outermost surface of the resin image and the silicon element abundance ratio within 3 nm from the outermost surface in the depth direction. The results are shown in Table 2.

  The measurement conditions are as follows.

X-ray: Al Monochromatic X-ray source Acceleration: 12 kV, 6 mA
Resolution: 50 eV
Beam diameter: 400 μm
Pass energy: 50 eV
Step size: 0.1 eV
In each of the examples and the comparative examples, the total amount (X) of the amounts of the elements corresponding to the elements having the thermal conductivity of 20 W · mK or more at the temperature of 300 K measured by ESCA for the resin images before the powder is supplied The abundance (Y) of the element exhibiting the metallic property measured by ESCA of the image after supplying the powder to the resin layer was determined as follows.

  First, for (X), a resin image before powder supply was prepared, and quantitative analysis of the elements contained in the resin image was performed by ESCA. When a plurality of corresponding elements are contained in the resin layer image, the plurality of elements were analyzed and the calculated abundance ratios were added. For (Y), an image after the powder was supplied to the resin layer was prepared, and quantitative analysis of elements contained in the supplied powder and exhibiting metallic property was performed by ESCA. In principle, ESCA has a measurement depth of several nanometers on the surface layer of the sample. Therefore, even if the powder to be decorated and the inorganic particles are the same element, the result of measuring the image after decoration shows only the decorated powder. It can be regarded as detecting.

The measurement conditions are as follows.
X-ray: Al Monochromatic X-ray source Acceleration: 12 kV, 6 mA
Resolution: 50 eV
Beam diameter: 400 μm
Pass energy: 50 eV
Step size: 0.1 eV.

(Powder adhesion evaluation)
In Examples and Comparative Examples, the fixing strength of images after powder decoration was evaluated by the tape peeling test method. Specifically, an adhesive tape (cellophane tape manufactured by Nichiban Co., Ltd.) with a width of 18 mm is attached to the fixed image, a cylindrical block is rolled in the circumferential direction on the adhesive tape, and the tape is imaged with a linear pressure of 300 g / cm. It was brought into close contact with the surface and then the adhesive tape was peeled off and evaluated according to the following criteria. Ranks 2 to 5 are practical, and rank 1 results are not acceptable. The results are shown in Table 2.
5: The image after powder decoration was missing from the image at an area ratio of less than 1.8%.
4: The image after powder decoration was missing from the image at an area ratio of 1.8% or more and less than 3%.
3: The image after powder decoration was missing from the image at an area ratio of 3% or more and less than 4%.
2: The image after powder decoration was missing from the image at an area ratio of 4% or more and less than 6%.
1: The image after powder decoration was missing from the image at an area ratio of 6% or more.

  Regarding the image defect, the image after the powder decoration was converted into data as a photograph, and then binarized using ImageJ software to determine the image defect. The range used for the determination is the area where the adhesive tape was used for peeling.

(Evaluation of metallicity of image)
The flop index value (color change depending on the viewing angle) was used as an index for evaluating the metallic property of the images obtained in each of the examples and comparative examples.

The flop index value is calculated by the following Expression 3. The value of lightness (L ^* ) required for calculation was measured with a multi-angle colorimeter (BYK-mac i). L ^* 15 ° is the lightness measured from the angle of 15 ° with respect to the image, and L ^* 45 ° is the lightness measured from the angle of 45 ° with respect to the image, L ^* 110 °. Is the lightness measured from the angle of 110 ° with respect to the image. Also, the higher the flop index value, the greater the color change depending on the viewing angle, and the higher the metallicity.

Based on the obtained flop index value, the metallic property was evaluated based on the following evaluation criteria. In addition, the result of x is not acceptable. The results are shown in Table 2.
⊚: Flop index value is 9.0 or more ○: Flop index value is 8.0 or more and less than 9.0 ×: Flop index value is less than 8.0

As can be seen from Table 2, Examples 1 to 30 are excellent in both the metallic property of the image and the powder adhesion property, and of these, Examples 8 to 12 have the best results. Comparing Example 8 and Example 14, the metallicity is almost the same in the case of using silica as in the case of using titanium oxide as the inorganic particles, but the peeling of the decorated powder is easy. Is considered to be suppressed. From the viewpoint of thermal conductivity, it is considered that Ti <Si, and Ti does not soften the entire resin layer uniformly as compared with Si, and a portion where the powder easily peels off occurs.
Examples 21 to 26 show that it is possible to contain a plurality of types of inorganic particles. In contrast to Examples 22 to 26, Example 8 is excellent in metallicity because the content of the whole inorganic particles in the resin layer is a preferable amount, and the powder to be decorated has a good adhesion. Can be considered. Further, it is considered that since it does not contain inorganic particles derived from an element having a high thermal conductivity other than silica, it is in a state in which the powder is unlikely to sink.

  On the other hand, in Comparative Example 1, since the inorganic particles are not used, the powder is embedded in the image, the metallic property of the image is deteriorated, and the powder is embedded unevenly, so that the image of the powder is formed. It is arranged so as to project to the surface, and the state in which it is easily removed reduces the adhesion of the powder. In Comparative Examples 2 to 6, it is considered that the number average primary particle diameter of the inorganic particles was out of the range of the present invention, the image defect rate was high, and as a result, the metallic property of the image was also lowered.

1 Recording Medium 2 Fixed Image 10 Powder Supply Device (Powder Supply Means)
11 powder container 12 powder supply roller 20 heating device (heating means)
30 rubbing member (rubbing means)

Claims (7)

An image forming method, comprising: a step of softening a resin layer formed on a recording medium; and a step of supplying powder onto the recording medium,
The image forming method, wherein the resin layer contains at least one kind of inorganic particles, and the number average primary particle diameter of the inorganic particles is 5 nm or more and 500 nm or less.   The image forming method according to claim 1, wherein the inorganic particles contain a compound derived from an element having a thermal conductivity of 20 W · mK or more at a temperature of 300K. The said resin layer WHEREIN: The ratio of the amount of silicon elements with respect to the total of the amount of carbon elements, the amount of oxygen elements, and the amount of silicon elements measured by X-ray photoelectron spectroscopy analysis (ESCA) satisfy | fills the following (1), 1 or 2. The image forming method described in 2.
The amount of an element having a thermal conductivity of 20 W · mK or higher at a temperature of 300 K measured by X-ray photoelectron spectroscopy (ESCA) of the resin layer is defined as X, and ESCA of the image after the powder is supplied to the resin layer The image forming method according to claim 2 or 3, wherein the following formula (2) is satisfied, where Y is the amount of the element exhibiting the metallic property to be measured.
  The image forming method according to claim 1, further comprising a step of rubbing the resin image supplied with the powder from the resin layer side.   The image forming method according to claim 5, wherein the step of rubbing the resin image supplied with the powder from the resin layer side includes rubbing by a relative speed difference between a recording medium and a rubbing member. ..   The image forming method according to claim 1, wherein the powder is a non-spherical powder.