JP7289721B2 - white toner - Google Patents

Description

The present invention relates to a white toner used in an electrophotographic image forming method.

In recent years, with the development of image forming apparatuses such as copiers and printers, there is a demand for toners that can be used with various media. Among them, a technique has been developed to obtain a printed matter with a high added value by using a special color toner such as a transparent toner or a white toner.

A white toner is used to form a white image on colored paper or a transparent film, and it is important that it has a high hiding rate. In order to achieve high hiding power, a toner using a material having a high refractive index such as titanium oxide has been developed (Patent Document 1).

JP-A-2000-56514

Generally, in order to form a white image using a white toner and express a sufficient white color, it is preferable to hide the underlying color so that it cannot be recognized. Such image hiding properties are manifested by scattering of light in the image film, so the pigment should be colorless and have a large difference in refractive index from the binder resin, that is, a material with a high refractive index. is required.

Furthermore, in the white toner, in order to exhibit sufficient hiding power, it is necessary to contain the above white pigment in the toner in a large amount and with good dispersibility as compared with other colors.

In order to solve such a problem, by using a resin having a low refractive index such as a silicone resin as a main component as a binder resin, it is possible to increase the difference in refractive index from that of the white pigment and improve the degree of whiteness. . However, since these resins have high releasability and low adhesiveness to various media, the images tend to be inferior in abrasion resistance.

As a result of intensive studies by the present inventors, it has been found that the above problems can be solved by using resin A containing either one of a siloxane group and a fluoro group and further containing an ester group as the main component of the binder resin in the toner. I found

Since the resin contains a siloxane group or a fluoro group, the refractive index of the resin is lowered. As a result, the difference between the refractive index and the white pigment is increased, and the whiteness is improved. In addition, by including an ester group, the cohesive force of the toner layer increases, and as a result of the bonding force such as hydrogen bonding and electrostatic interaction between the resin and the media, the degree of adhesion of the image to the media increases. , the scratch resistance of the image is improved. Further, in the case of the present invention, these units are contained within the same resin. It is believed that the cohesive force of the toner layer in the image is higher than when individual resins are mixed, and as a result, an image with a high degree of whiteness can be obtained while maintaining high abrasion resistance.

That is, the toner of the present invention is
A white toner comprising toner particles having a binder resin and a white pigment,
The binder resin contains resin A,
Resin A is
(i) at least one selected from the group consisting of a siloxane bond and a fluoro group, and an ester bond;
(ii) contained in the binder resin in an amount of 50% by mass or more;
A white toner characterized by:

According to the present invention, it is possible to provide a white toner excellent in whiteness and abrasion resistance.

In the present invention, unless otherwise specified, the descriptions of "○○ or more and XX or less" and "○○ to XX", which represent numerical ranges, mean numerical ranges including the lower and upper limits that are endpoints.

The white toner of the present invention comprises toner particles. The toner particles contain a binder resin and a white pigment.

Each component is described below.

<Binder resin>
In the present invention, resin A is included in the binder resin.

Resin A contains (i) one of a siloxane bond and a fluoro group, and (ii) an ester bond. A siloxane bond represents (≡Si—O—), a fluoro group represents (—F), and an ester bond represents (—C(=O)—O—).

Specific examples of resin A include silicone-modified (meth)acrylic resins, silicone-modified styrene-(meth)acrylic resins, silicone-modified polyesters, fluorine-containing (meth)acrylic resins, fluorine-containing styrene-(meth)acrylic resins, fluorine-containing A polyester etc. are mentioned. Among these, silicone-modified polyester is preferable from the viewpoint of abrasion resistance.

The polyester portion contained in the silicone-modified polyester is preferably a polycondensation product of an alcohol component and an acid component. The following compounds are mentioned as a monomer which produces|generates a polyester part.

Examples of the alcohol component include the following divalent dialcohol components. Ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol , 2-ethyl-1,3-hexanediol, hydrogenated bisphenol A, bisphenol represented by the following formula (I) and derivatives thereof, and diols represented by the following formula (II) .

(In the formula, R represents an ethylene group or a propylene group, X and Y are each an integer of 0 or more, and the average value of X + Y is 0 or more and 10 or less.)

Bisphenols represented by formula (I) include polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (3.3)-2,2-bis( 4-hydroxyphenyl)propane, polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl)propane , polyoxypropylene (2.0)-polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl)propane, polyoxypropylene (6)-2,2-bis(4-hydroxyphenyl) propane and the like.

As the alcohol component, 1,2,3-propanetriol, trimethylolpropane, hexanetriol, pentaerythritol, etc. may be used as polyhydric alcohols having a valence of 3 or more.

Among these, as the alcohol component, aliphatic diols and bisphenols represented by formula (I) are preferable, and ethylene glycol and polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane are more preferred, and both are most preferred.

Divalent carboxylic acid is mentioned as an acid component. Benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride, and acid anhydrides or lower alkyl esters thereof; alkyldicarboxylic acids such as succinic acid, adipic acid, sebacic acid and azelaic acid, and these acids anhydride or lower alkyl ester; succinic acid substituted with an alkyl group having 6 to 18 carbon atoms or an alkenyl group having 6 to 18 carbon atoms, and its acid anhydride or lower alkyl ester; fumaric acid, maleic acid, citraconic acid, Unsaturated dicarboxylic acids such as itaconic acid, and their acid anhydrides or lower alkyl esters.

It is also preferable to use a polyvalent carboxylic acid having a valence of 3 or more as the acid component. Examples thereof include 1,2,4-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, pyromellitic acid, and acid anhydrides or lower alkyl esters thereof.

Among these, benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid and phthalic anhydride, and their acid anhydrides or lower alkyl esters are preferable as the acid component. Especially preferred are terephthalic acid and its acid anhydrides or lower alkyl esters (eg dimethyl terephthalate).

The resin A is contained in an amount of 50% by mass or more in the binder resin. More preferably, it is 60% by mass or more, and particularly preferably 80% by mass or more. Within the above range, the refractive index of the binder resin is lowered and the cohesive force of the toner layer is improved, so that both whiteness and abrasion resistance can be achieved.

The refractive index n1 of the binder resin containing the resin A is preferably 1.55 or less, more preferably 1.52 or less. Within the above range, the balance between the refractive index and the cohesive force of the binder resin is improved, and both whiteness and abrasion resistance can be achieved.

The ester bond concentration contained in Resin A is preferably 5% to 30% by mass, more preferably 10% to 20% by mass. Within the above range, the cohesive force of the resin A and the interaction with the media are strengthened, and the abrasion resistance is improved.

The binder resin may contain a resin other than the resin A, and known polymers can be used as the other resin. Specifically, the following polymers can be used.

Homopolymers of styrene and substituted products thereof such as polystyrene, poly-p-chlorostyrene and polyvinyltoluene; styrene-p-chlorostyrene copolymers, styrene-vinyltoluene copolymers, styrene-vinylnaphthalene copolymers, styrene - acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-methyl chloromethacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether Styrenic copolymers such as copolymers, styrene-vinyl methyl ketone copolymers, styrene-acrylonitrile-indene copolymers; polyvinyl chloride, phenolic resin, natural resin-modified phenolic resin, natural resin-modified maleic acid resin, acrylic Resins, methacrylic resins, polyvinyl acetate, polyesters, polyurethanes, polyamides, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone-indene resins, petroleum-based resins, and the like. These resins may be used individually by 1 type, and may use 2 or more types together.

<White pigment>
The toner particles of the present invention contain a white pigment.

Examples of white pigments include titanium oxide particles, magnesium oxide particles, aluminum oxide particles, zinc oxide particles, barium sulfate particles), calcium carbonate particles, calcium titanate particles, strontium titanate particles, silica particles, clay, talc, and the like. mentioned. These white pigments may or may not be surface-treated.

Among these, titanium oxide particles and calcium titanate particles are preferred. Titanium oxide particles with a high refractive index are preferred from the viewpoint of whiteness, and calcium titanate particles with a high surface interaction force are preferred from the viewpoint of abrasion resistance.

The white pigment content in the toner particles is preferably 10% to 40% by volume, more preferably 15% to 35% by volume. By being within the above range, the white pigment is present in an appropriate amount, so that both whiteness and scratch resistance are achieved.

Further, when the refractive index of the white pigment is n2, the refractive index n1 and the refractive index n2 of the binder resin are
n2-n1≧0.80
preferably satisfies
n2-n1≧0.88
It is more preferable to satisfy Within the above range, the difference in refractive index between the resin and the white pigment is increased, and the degree of whiteness is improved.

The volume average particle size Dw of the white pigment is preferably 150 nm to 550 nm, more preferably 180 nm to 300 nm. Within the above range, the whiteness is improved.

The volume average particle size Dw (nm) of the white pigment preferably satisfies the following formula in relation to the refractive index n1 of the binder resin and the refractive index n2 of the white pigment.
550/{2.1(n2-n1)}-50≤Dw≤550/{2.1(n2-n1)}+50
The above relational expression is a formula that represents the particle size of the white pigment that maximizes the scattering of light with a wavelength of 550 nm (second edition, titanium oxide (Gihodo Publishing), pp. 130-131). Good light scattering efficiency and good whiteness can be obtained.

<Release agent>
The toner particles may optionally contain a release agent.

Examples of release agents include the following. low molecular weight polyolefins such as polyethylene; fatty acid amides such as oleic acid amide, erucic acid amide, ricinoleic acid amide and stearic acid amide; ester waxes such as stearyl stearate; carnauba wax, rice wax, candelilla wax , wood wax and jojoba oil; animal waxes such as beeswax; mineral and petroleum waxes such as montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax, Fischer-Tropsch wax and ester wax; and modified products thereof.

The release agent is preferably contained in the toner particles in an amount of 1% by mass to 10% by mass.

The melting point of the release agent is preferably 50°C to 100°C, more preferably 70°C to 100°C.

<Method for producing toner particles>
A method for producing toner particles is not particularly limited, and known methods such as an emulsion aggregation method, a pulverization method, and a suspension polymerization method can be used.

In the following, the toner manufacturing procedure using the pulverization method will be described as an example.

In the raw material mixing step, predetermined amounts of other components such as a binder resin, a white pigment, and, if necessary, a release agent and a charge control agent are weighed and mixed as materials constituting toner particles. Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a Nauta mixer, and a Mechanohybrid (manufactured by Nippon Coke Kogyo Co., Ltd.).

The mixed materials are then melt-kneaded. In the melt-kneading step, a batch-type kneader such as a pressure kneader or a Banbury mixer, or a continuous kneader can be used, and a single-screw or twin-screw extruder is preferable from the standpoint of continuous production. The melt-kneading temperature is preferably about 100 to 200°C. Examples of kneaders include KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), PCM kneader (manufactured by Ikegai Iron Works), twin-screw extruder (Kei · C.K. Co., Ltd.), Co-kneader (manufactured by Buss Co., Ltd.), Kneadex (manufactured by Nippon Coke Kogyo Co., Ltd.), and the like. After melt-kneading, the resulting resin composition is rolled with two rolls or the like, and quenched with water or the like in the cooling step.

The cooled resin composition is then ground to the desired particle size in a grinding step. In the pulverization process, for example, after coarse pulverization with a pulverizer such as a crusher, hammer mill, or feather mill, for example, Kryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), Turbo · Finely pulverize with a mill (manufactured by Turbo Kogyo) or an air jet type pulverizer.

After that, if necessary, inertial classification method Elbow Jet (manufactured by Nittetsu Mining Co., Ltd.), centrifugal force classification method Turboplex (manufactured by Hosokawa Micron Corporation), TSP Separator (manufactured by Hosokawa Micron Corporation), Faculty (manufactured by Hosokawa Micron Corporation) Classify using a classifier or sieving machine to obtain a classified product.

Furthermore, if necessary, the obtained classified product may be subjected to shape adjustment and surface treatment by using a heating surface treatment apparatus as shown in FIG.

In FIG. 1, the mixture supplied by the raw material constant supply means 1 is guided to the introduction pipe 3 installed on the central axis of the processing chamber 6 by the compressed gas adjusted by the compressed gas adjustment means 2 . The mixture that has passed through the introduction pipe is uniformly dispersed by a conical protruding member 4 provided in the central portion of the raw material supply means, is guided to the supply pipes 5 extending radially in eight directions, and is fed to the powder particle supply port 14. From there, it is led to a processing chamber 6 where heat treatment is performed.

At this time, the flow of the mixture supplied to the processing chamber 6 is regulated by the regulating means 9 provided in the processing chamber 6 for regulating the flow of the mixture. Therefore, the mixture supplied to the processing chamber 6 is heat-treated while swirling in the processing chamber 6 and then cooled.

Hot air for heat-treating the supplied mixture is supplied from the hot-air inlet 7 of the hot-air supply means 7, and the hot air is helically swirled and introduced into the processing chamber 6 by the swirling member 13 for swirling the hot air. be done. As for the configuration, the swirling member 13 for swirling the hot air has a plurality of blades, and the swirling of the hot air can be controlled by the number and angle of the blades. At this time, the substantially conical distribution member 12 can reduce the unevenness of the swirling hot air.

The hot air supplied into the processing chamber 6 preferably has a temperature of 100° C. to 300° C. at the hot air outlet 11 of the hot air supplying means 7 . If the temperature at the hot air outlet 11 of the hot air supply means 7 is within the above range, the toner particles can be uniformly sphericalized while preventing the toner particles from being fused or coalesced due to excessive heating of the mixture. becomes possible.

The toner particles obtained through the above steps may be used as a toner as they are. If necessary, the surface of the toner particles may be externally added with an external additive to form a toner. As a method for externally adding an external additive, toner particles and various known external additives are blended in a predetermined amount, and mixed with a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, a nauta mixer, and a mechanohybrid (mechanohybrid). Nippon Coke Kogyo Co., Ltd.), Nobilta (Hosokawa Micron Co., Ltd.) or other mixing device is used as an external addition device to stir and mix.

In the present invention, the toner preferably has a volume-based median diameter of 3.0 μm to 30.0 μm, more preferably 4.0 μm to 20.0 μm.

<Method for measuring each physical property>
Methods for measuring physical properties related to the present invention are described below.

[Content of Resin A in Binder Resin in Toner Particles]
160 g of sucrose (manufactured by Kishida Chemical Co., Ltd.) is added to 100 mL of ion-exchanged water and dissolved in a hot water bath to prepare a concentrated sucrose solution. In a centrifugation tube, 31 g of the concentrated sucrose solution, Contaminon N (a 10% by mass aqueous solution of a neutral detergent for cleaning precision measuring instruments at pH 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, (manufactured by Wako Pure Chemical Industries, Ltd.) is added to prepare a dispersion. 1.0 g of toner is added to this dispersion, and clumps of toner are loosened with a spatula or the like. The centrifuge tube is then shaken on a shaker. After shaking, the solution is replaced in a swing rotor glass tube (50 mL) and separated in a centrifuge at 3500 rpm for 30 minutes. This operation separates the toner particles from the detached external additive. After visually confirming that the toner particles and the aqueous solution are sufficiently separated, the toner particles are collected, filtered with a vacuum filter, and then dried with a dryer for 1 hour or longer to separate the external additives from the toner particles. get

Next, the binder resin or resin A is separated from the toner particles by utilizing the difference in solubility in the solvent, and the mass of each is measured to determine the resin A content. Specific methods for separation include, for example, the following methods.

First separation: Toner particles are dissolved in methyl ethyl ketone (MEK) at 23° C. to separate soluble matter (binder resin containing resin A) and insoluble matter (white pigment, release agent, etc.). By drying and solidifying the soluble component and measuring the mass, the mass of the binder resin in the toner is obtained.

Second separation: The soluble matter (binder resin containing resin A) obtained in the first separation is dissolved in ethyl acetate at 23°C to separate the soluble matter and the insoluble matter. At this time, since the resin A according to the present invention is usually insoluble in ethyl acetate, the insoluble matter becomes the resin A. The obtained insoluble matter is dried and the mass is measured to obtain the mass of the resin A in the toner.

Then, the content of resin A is calculated from the masses of the binder resin and resin A thus obtained.

[Volume average particle size Dw of white pigment]
An Os film (5 nm) and a naphthalene film (20 nm) were applied to the toner particles as protective films using an osmium plasma coater (OPC80T, manufactured by Filgen), and embedded in a photocurable resin D800 (JEOL Ltd.). An ultrasonic ultramicrotome (UC7, Leica) is used to prepare a toner particle cross section with a film thickness of 60 nm at a cutting speed of 1 mm/s. A toner particle cross section is observed using a transmission electron microscope or the like to obtain a toner particle cross section image. Particles in the cross-sectional image are identified using an energy dispersive X-ray spectrometer (EDX) or the like.

The area of the white pigment present in the cross-sectional image of the toner particles is measured to calculate the equivalent circle diameter. This is performed for 100 white pigments, and the volume average particle diameter is calculated based on the circle equivalent diameters of 100 particles.

Toner particle cross-sectional images to be measured are selected as follows. From the toner particle cross-sectional image, the cross-sectional area of the toner particle is determined, and the diameter of a circle having an area equal to the cross-sectional area (equivalent circle diameter) is determined. The domain diameter is calculated only for toner particle cross-sectional images in which the absolute value of the difference between the equivalent circle diameter and the weight average particle diameter (D4) of the toner is within 1.0 μm. Since the domain diameter may change depending on the particle size of the toner particles, the average domain diameter can be calculated in this manner.

[Content ratio of white pigment in toner particles (% by volume)]
Since the white pigment is usually insoluble in the solvent, the white pigment may be separated by removing the other components using the solvent. Specific methods for separation include, for example, the following methods.

The insoluble matter (white pigment, release agent, etc.) obtained in the first separation described above is dissolved in toluene at 100° C. to separate the soluble matter and the insoluble matter. At this time, since the white pigment is insoluble in toluene, the insoluble portion becomes the white pigment. The obtained insoluble matter is dried and the mass of the obtained white pigment is measured. Further, the density of the white pigment is measured using a true densitometer, and the volume is calculated.

On the other hand, the volume of the toner particles is measured using means such as the above-described true density meter or Coulter particle size distribution analyzer (eg, Beckman Coulter, Multisizer series).

The content ratio (% by volume) of the white pigment is calculated from the volumes of the obtained white pigment and toner particles.

[Refractive index of resin A]
Using the binder resin separated by the above method, refracting is performed with an Abbe refractometer (eg, DR-M2 (manufactured by Ohara Co., Ltd.)) or a spectroscopic ellipsometer (eg, VASE, manufactured by J.A. Woollam Japan, etc.). Make rate measurements.

[Refractive index of white pigment]
Using the white pigment isolated by the above method, Abbe refractometer (e.g., DR-M2 (manufactured by Ohara Co., Ltd.)), or spectroscopic ellipsometer (e.g., VASE, JA Woollam Japan, etc.) Refraction Make rate measurements.

EXAMPLES The present invention will be described in more detail below using examples and comparative examples, but these are not intended to limit the present invention in any way. In the following prescriptions, "parts" are based on mass unless otherwise specified.

<Example 1>
(Synthesis of silicone-modified polyester 1)
・Dimethyl terephthalate 386 parts ・Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane
206 parts Ethylene glycol 25 parts The above materials were added to a reactor equipped with a condenser, stirrer, nitrogen inlet, and thermocouple. Further, a titanium-based catalyst (tetrabutyl titanate) was added, and after the inside of the reactor was replaced with nitrogen gas, the temperature was gradually raised while stirring, and the polymerization reaction was carried out while stirring at 200° C. and reducing the pressure. After cooling to room temperature and removing unreacted monomers and generated methanol, 125 parts of one-end alcohol-modified silicone oil (X-22-170DX: manufactured by Shin-Etsu Chemical Co., Ltd.) is added, and the inside of the reaction vessel is replaced with nitrogen gas. bottom. Thereafter, the temperature was gradually raised while stirring, and the mixture was reacted at 200° C. while stirring and reduced pressure to obtain a silicone-modified polyester 1 (Mw=41000, Mw/Mn=9).

(Preparation of Toner 1)
・Silicone-modified polyester 1 48 parts ・Titanium oxide particles 1 (rutile type, volume average particle diameter 210 nm) 48 parts ・Fischer-Tropsch wax (melting point 78 ° C.) 4 parts ) was used to mix at a rotation speed of 20 s ⁻¹ and a rotation time of 5 min, and then kneaded with a twin-screw kneader (PCM-30 type, manufactured by Ikegai Co., Ltd.) set at a temperature of 130°C. The resulting kneaded product was cooled to 25° C. and coarsely pulverized to 1 mm or less with a hammer mill to obtain a coarsely pulverized product. The coarsely crushed product obtained was finely pulverized with a mechanical pulverizer (T-250, manufactured by Turbo Kogyo Co., Ltd.). Furthermore, classification was performed using Faculty F-300 (manufactured by Hosokawa Micron Corporation).

Further, the classified particles were heat-treated by the surface treatment apparatus shown in FIG. The operating conditions were feed rate = 3 kg/hr, hot air temperature = 130°C, hot air flow rate = 6 m ³ /min, cold air temperature = -5°C, cold air flow rate = 4 m ³ /min, blower air flow rate = 20 m ³ /min, The injection air flow rate was set to 1 m ³ /min. By performing heat treatment, toner particles 1 having an average circularity of 0.96 were obtained.

For 100 parts of the obtained toner particles 1,
・ 1.5 parts of hydrophobized silica fine powder having a primary particle number average diameter of 10 nm ・ 2.5 parts of hydrophobized silica fine powder having a primary particle number average diameter of 100 nm Toner 1 was obtained by dry-mixing at a manufacturer. The volume-based median diameter of Toner 1 was 6.5 μm.

<Example 2>
(Synthesis of silicone-modified styrene methacrylic resin 1)
・One-end vinyl-modified silicone oil (X-22-2475: manufactured by Shin-Etsu Chemical Co., Ltd.) 20 parts ・Styrene 54 parts ・Methyl methacrylate 26 parts ・Toluene 800 parts In a heat-dried two-necked flask, while introducing nitrogen. The above materials were mixed and heated to 70° C. to dissolve completely. The temperature was lowered to 25° C. while stirring, nitrogen was bubbled through the mixture, and then 0.6 part of azobismethoxydimethylvaleronitrile was mixed as a polymerization initiator. After that, the mixture was heated at 75° C., reacted for 6 hours, further heated to 80° C., and reacted for 1 hour. After filtering the resulting reaction solution, toluene was removed by drying to obtain a silicone-modified styrene methacrylic resin 1 (Mw=48000, Mw/Mn=5).

(Preparation of Toner 2)
・Silicone-modified styrene methacrylic resin 1 48 parts ・Titanium oxide particles 1 (rutile type, volume average particle diameter 210 nm) 48 parts ・Fischer-Tropsch wax (melting point 78 ° C.) 4 parts In the same manner as in Example 1 except that the above materials are used. , Toner 2 was obtained.

<Example 3>
(Synthesis of fluorine-containing styrene acrylic resin 1)
・2,2,2-Trifluoroethyl methacrylate 40 parts ・Styrene 55 parts ・Butyl acrylate 5 parts ・Toluene 800 parts In a heat-dried two-necked flask, the above materials were mixed while introducing nitrogen, and the temperature was raised to 70 ° C. Heat to dissolve completely. The temperature was lowered to 25° C. while stirring, nitrogen was bubbled through the mixture, and then 0.6 part of azobismethoxydimethylvaleronitrile was mixed as a polymerization initiator. After that, the mixture was heated at 75° C., reacted for 6 hours, further heated to 80° C., and reacted for 1 hour. After filtering the resulting reaction solution, the toluene was removed by drying to obtain fluorine-containing styrene acrylic resin 1 (Mw=47000, Mw/Mn=5).

(Preparation of Toner 3)
・Fluorine-containing styrene acrylic resin 1 48 parts ・Titanium oxide particles 1 (rutile type, volume average particle diameter 210 nm) 48 parts ・Fischer-Tropsch wax (melting point 78 ° C.) 4 parts In the same manner as in Example 1 except that the above materials are used. , Toner 3 was obtained.

<Examples 4 to 7>
Toners 4 to 7 were obtained in the same manner as in Example 1, except that titanium oxide particles 1 were changed to the following titanium oxides.
Example 4: Titanium oxide particles 2 (rutile type, volume average particle size 150 nm)
Example 5: Titanium oxide particles 3 (rutile type, volume average particle size 290 nm)
Example 6: Titanium oxide particles 4 (rutile type, volume average particle size 130 nm)
Example 7: Titanium oxide particles 5 (rutile type, volume average particle size 600 nm)
<Example 8>
(Synthesis of silicone-modified polyester 2)
Silicone-modified polyester 2 (Mw = 45000, Mw/Mn=11).

(Preparation of Toner 8)
Toner 8 was obtained in the same manner as in Example 1, except that silicone-modified polyester 1 was changed to silicone-modified polyester 2.

<Examples 9 to 12>
Toners 9 to 12 were obtained in the same manner as in Example 1, except that the amounts of silicone-modified polyester 1 and titanium oxide particles 1 added were changed as shown in Table 1.

<Example 13>
(Synthesis of silicone-modified styrene methacrylic resin 2)
・One-end vinyl-modified silicone oil (X-22-2475: manufactured by Shin-Etsu Chemical Co., Ltd.) 20 parts ・Styrene 70 parts ・Methyl methacrylate 10 parts ・Toluene 800 parts In the same manner as in Example 2 except that the above materials are used. , a silicone-modified styrene methacrylic resin 2 (Mw=49000, Mw/Mn=5) was synthesized.

(Preparation of Toner 13)
Toner 13 was obtained in the same manner as in Example 1, except that silicone-modified polyester 1 was changed to silicone-modified styrene methacrylic resin 2.

<Example 14>
・ Silicone-modified polyester 1 27 parts ・ Polyester 1 23 parts [composition (mol%) [polyoxyethylene (2.2)-2,2-bis (4-hydroxyphenyl) propane / polyoxypropylene (2.2)- 2,2-bis(4-hydroxyphenyl)propane/terephthalic acid/fumaric acid = 60/40/90/10], Mw = 45000, Mw/Mn = 10]
• Titanium oxide particles 1 (rutile type, volume average particle size: 210 nm) 46 parts • Fischer-Tropsch wax (melting point: 78°C) 4 parts Toner 14 was obtained in the same manner as in Example 1 except that the above materials were used.

<Comparative Example 1>
- Silicone-modified polystyrene 1 47 parts [styrene-dimethylsiloxane-styrene block copolymer, composition (mol%) [styrene/dimethylsiloxane/styrene = 30/40/30], Mw = 30,000, Mw/Mn = 3 ]
• Titanium oxide particles 1 (rutile type, volume average particle size: 210 nm) 49 parts • Fischer-Tropsch wax (melting point: 78°C) 4 parts Toner 15 was obtained in the same manner as in Example 1 except that the above materials were used.

<Comparative Example 2 (manufacture of reference toner)>
(Synthesis of Polyester 2)
・Dimethyl terephthalate 386 parts ・Polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl)propane
206 parts Ethylene glycol 25 parts To a reaction vessel equipped with a condenser, stirrer, nitrogen inlet tube, and thermocouple, the above materials were added. Furthermore, after adding a titanium-based catalyst (tetrabutyl titanate) and replacing the inside of the reaction vessel with nitrogen gas, the temperature is gradually raised while stirring, and the polymerization reaction is performed while stirring at 200 ° C. and reducing the pressure to polyester 2. (Mw=35000, Mw/Mn=8).

(Preparation of Toner 16)
Polyester 2 52 parts Titanium oxide particles 1 (rutile type, volume average particle diameter 210 nm) 44 parts Fischer-Tropsch wax (melting point 78° C.) 4 parts Toner 16 was prepared in the same manner as in Example 1 except that the above materials were used. Obtained.

<Comparative Example 3 (manufacture of reference toner)>
(Synthesis of styrene methacrylic resin 1)
- Styrene 54 parts - Methyl methacrylate 26 parts - Toluene 800 parts In a heat-dried two-necked flask, while introducing nitrogen, the above materials were mixed and heated to 70°C to dissolve completely. The temperature was lowered to 25° C. while stirring, nitrogen was bubbled through the mixture, and then 0.6 part of azobismethoxydimethylvaleronitrile was mixed as a polymerization initiator. After that, the mixture was heated at 75° C., reacted for 6 hours, further heated to 80° C., and reacted for 1 hour. After filtering the obtained reaction solution, toluene was removed by drying to obtain styrene methacrylic resin 1 (Mw=43000, Mw/Mn=4).

(Preparation of Toner 17)
・Styrene methacrylic resin 1 50 parts ・Titanium oxide particles 1 (rutile type, volume average particle diameter 210 nm) 46 parts ・Fischer-Tropsch wax (melting point 78° C.) 4 parts A toner was prepared in the same manner as in Example 1 except that the above materials were used. 17 was obtained.

<Comparative Example 4 (manufacture of reference toner)>
(Synthesis of styrene acrylic resin 1)
- Styrene 55 parts - Butyl acrylate 5 parts - Toluene 800 parts In a heat-dried two-necked flask, the above materials were mixed while introducing nitrogen and heated to 70°C to dissolve completely. The temperature was lowered to 25° C. while stirring, nitrogen was bubbled through the mixture, and then 0.6 part of azobismethoxydimethylvaleronitrile was mixed as a polymerization initiator. After that, the mixture was heated at 75° C., reacted for 6 hours, further heated to 80° C., and reacted for 1 hour. After filtering the obtained reaction solution, toluene was removed by drying to obtain styrene acrylic resin 1 (Mw=41000, Mw/Mn=4).

(Preparation of Toner 18)
・Styrene acrylic resin 1 50 parts ・Titanium oxide particles 1 (rutile type, volume average particle diameter 210 nm) 46 parts ・Fischer-Tropsch wax (melting point 78° C.) 4 parts A toner was prepared in the same manner as in Example 1 except that the above materials were used. 18 was obtained.

<Comparative Examples 5 to 8 (production of reference toner)>
Toners 19 to 22 were obtained in the same manner as in Comparative Example 2, except that titanium oxide particles 1 were changed to titanium oxide particles 2 to 5.
Comparative Example 5: Titanium oxide particles 2 (rutile type, volume average particle diameter 150 nm)
Comparative Example 6: Titanium oxide particles 3 (rutile type, volume average particle diameter 290 nm)
Comparative Example 7: Titanium oxide particles 4 (rutile type, volume average particle size 130 nm)
Comparative Example 8: Titanium oxide particles 5 (rutile type, volume average particle diameter 600 nm)

<Comparative Examples 9 to 12 (production of reference toner)>
Toners 23 to 26 were obtained in the same manner as in Comparative Example 2, except that the amounts of polyester 2 and titanium oxide particles 1 added were changed as shown in Table 1.

<Comparative Example 13 (manufacture of reference toner)>
(Synthesis of styrene methacrylic resin 2)
- Styrene 70 parts - Methyl methacrylate 10 parts - Toluene 800 parts In a heat-dried two-necked flask, the above materials were mixed while introducing nitrogen, and heated to 70°C to dissolve completely. The temperature was lowered to 25° C. while stirring, nitrogen was bubbled through the mixture, and then 0.6 part of azobismethoxydimethylvaleronitrile was mixed as a polymerization initiator. After that, the mixture was heated at 75° C., reacted for 6 hours, further heated to 80° C., and reacted for 1 hour. After filtering the resulting reaction solution, toluene was removed by drying to obtain styrene methacrylic resin 2 (Mw=44000, Mw/Mn=4).

(Preparation of Toner 27)
・Styrene methacrylic resin 2 50 parts ・Titanium oxide particles 1 (rutile type, volume average particle diameter 210 nm) 46 parts ・Fischer-Tropsch wax (melting point 78° C.) 4 parts A toner was prepared in the same manner as in Example 1 except that the above materials were used. 27 was obtained.

<Comparative Example 14 (manufacture of reference toner)>
Toner 28 was obtained in the same manner as in Comparative Example 1, except that silicone-modified polystyrene 1 was changed to polystyrene 1 [Mw=20,000, Mw/Mn=3].

<Preparation of two-component developer>
Toners 1 to 28 obtained above and a ferrite carrier (number average particle size 42 μm) surface-coated with a silicone resin were mixed so that the toner concentration was 8% by mass to prepare a two-component developer.

Using the obtained two-component developer, the following evaluations were carried out. The evaluation results are shown in Table 3.

<Evaluation of Whiteness>
A commercial full-color digital copier (CLC1100, manufactured by Canon Inc.) was filled with the obtained two-component developer, and an unfixed area of 2 cm x 5 cm was placed in the center of black paper (Nagatoya Shoten, A4 paper, Na-3285). A toner image (toner lay-on amount: 1.0 mg/cm ² ) was formed. Fixing was performed using a fixing unit removed from a commercially available full-color digital copier (image RUNNER ADVANCE C5051, manufactured by Canon). At this time, fixing was performed while raising the fixing temperature by 5°C from 100°C. Using an X-Rite color reflection densitometer (500 series: manufactured by X-Rite), each fixed image in a fixing temperature range in which no offset occurs was measured for lightness L ^* , and the maximum lightness L ^* among them was measured. was defined as the whiteness of the toner.

Next, the effect of the present invention on whiteness was evaluated as follows.

In the toners of Examples 1 to 14 and Comparative Example 1, the rate of change in whiteness was compared with toners (Comparative Examples 2 to 14) in which Resin A was replaced with a resin that did not contain a siloxane group or a fluoro group. The rate of change was taken as the whiteness improvement rate, and the larger the value, the higher the effect on the whiteness.

For example, in the case of toner 1, toner 16 obtained by replacing silicone-modified polyester 1 with polyester 2 was used as a reference toner, and the whiteness improvement rate was calculated from the following equation.
Whiteness improvement rate (%)=(whiteness of toner 1−whiteness of toner 16)/(whiteness of toner 16)×100
(Evaluation criteria for whiteness)
A: Whiteness improvement rate of 7.0% or more B: Whiteness improvement rate of 5.0% or more and less than 7.0% C: Whiteness improvement rate of 2.0% or more and less than 5.0% D: Whiteness Less than 2.0% improvement

<Evaluation of abrasion resistance>
A commercial full-color digital copier (CLC1100, manufactured by Canon Inc.) was filled with the obtained two-component developer, and an unfixed area of 2 cm x 5 cm was placed in the center of black paper (Nagatoya Shoten, A4 paper, Na-3285). A toner image (toner lay-on amount: 1.2 mg/cm ² ) was formed. Fixing was performed using a fixing unit removed from a commercially available full-color digital copier (image RUNNER ADVANCE C5051, manufactured by Canon). At this time, fixing was carried out while raising the fixing temperature from 100° C. by 5° C., and a weight of 55 g/cm ² was applied to 5 fixed images at the maximum temperature at which high temperature offset did not occur, and rubbed 10 times with silbon paper. bottom. A 512-pixel square area of the cross was then photographed with a CCD camera at a resolution of 800 pixels/inch. The threshold was set to 60%, the image was binarized, and the area ratio of the black portion where the toner was peeled off was measured. The smaller the area ratio of the black portions, the better the scratch resistance.

(Evaluation Criteria for Scratch Resistance)
A: Area ratio of black portion is less than 2.0% B: Area ratio of black portion is 2.0% or more and less than 3.5% C: Area ratio of black portion is 3.5% or more and less than 5.0% D: Black portion Area ratio is 5.0% or more

In Table 1, the resin indicated by *1 and polyester 1 are resins that do not meet the requirements for resin A.

In Table 2, the resin indicated by *1 and polyester 1 are resins that do not meet the requirements for resin A.

Also, the formula of *2 is
550/{2.1(n2-n1)}-50≤Dw≤550/{2.1(n2-n1)}+50
It's about.

Table 3 shows the evaluation results of each example and comparative example. Toner 1 had a whiteness (lightness L ^* ) of 85.

<Example 15>
Toner 29 was obtained in the same manner as in Example 1, except that titanium oxide particles 1 were changed to calcium titanate particles 1 (volume average particle diameter: 300 nm).

<Example 16>
Toner 30 was obtained in the same manner as in Example 2 except that titanium oxide particles 1 were changed to calcium titanate particles 1 .

<Comparative Example 15 (manufacture of reference toner)>
Toner 31 was obtained in the same manner as in Comparative Example 2 except that titanium oxide particles 1 were changed to calcium titanate particles 1 .

<Comparative Example 16 (manufacture of reference toner)>
Toner 32 was obtained in the same manner as in Comparative Example 3 except that titanium oxide particles 1 were changed to calcium titanate particles 1 .

<Example 17>
・Silicone-modified polyester 1 41 parts ・Strontium titanate particles 1 (volume average particle diameter 300 nm) 55 parts ・Fischer-Tropsch wax (melting point 78° C.) 4 parts In the same manner as in Example 1 except that the above materials are used, toner 33 is prepared. Obtained.

<Comparative Example 17 (manufacture of reference toner)>
Polyester 2 45 parts Strontium titanate particles 1 (volume average particle diameter 300 nm) 51 parts Fischer-Tropsch wax (melting point 78° C.) 4 parts Toner 34 was obtained in the same manner as in Example 1 except that the above materials were used. .

<Example 18>
・Silicone-modified polyester 1 38 parts ・Zinc oxide particles 1 (volume average particle diameter: 500 nm) 58 parts ・Fischer-Tropsch wax (melting point: 78°C) 4 parts Toner 35 was obtained in the same manner as in Example 1 except that the above materials were used. rice field.

<Comparative Example 18 (manufacture of reference toner)>
Toner 36 was obtained in the same manner as in Example 1, except that the above materials were used.

<Preparation of two-component developer>
Toners 29 to 36 obtained above and a ferrite carrier (number average particle diameter 42 μm) surface-coated with a silicone resin were mixed so that the toner concentration was 8% by mass to prepare a two-component developer.

The same evaluation as in Example 1 was performed using the obtained two-component developer. The evaluation results are shown in Table 6.

In Table 4, resins marked with *1 are resins that do not meet the requirements for resin A.

Resins marked with *1 in Table 5 are resins that do not meet the requirements for resin A.

Also, the formula of *2 is
550/{2.1(n2-n1)}-50≤Dw≤550/{2.1(n2-n1)}+50
It's about.

Table 6 shows the evaluation results of each example. The whiteness (brightness L ^* ) of Toner 29 was 79.

Claims (9)

A white toner comprising toner particles having a binder resin and a white pigment,
The binder resin contains resin A,
Resin A is
(i) at least one selected from the group consisting of a siloxane bond and a fluoro group, and an ester bond;
(ii) contained in the binder resin in an amount of 50% by mass or more;
A white toner characterized by: 2. The white toner according to claim 1, wherein the white pigment is contained in the toner particles in an amount of 10% by volume to 40% by volume. When the refractive index of the binder resin is n1 and the refractive index of the white pigment is n2, the n1 and the n2 are
n2-n1≧0.80
3. The white toner according to claim 1 or 2, which satisfies: 4. The white toner according to claim 3 , wherein said n1 is 1.55 or less. 5. The white toner according to claim 1, wherein the white pigment has a volume average particle size Dw (nm) of 150 nm to 550 nm. 6. The following formula is satisfied, where Dw (nm) is the volume average particle size of the white pigment, n1 is the refractive index of the binder resin, and n2 is the refractive index of the white pigment. The white toner described in .
550/{2.1(n2-n1)}-50≤Dw≤550/{2.1(n2-n1)}+50 The white toner according to any one of claims 1 to 6, wherein the resin A has an ester bond concentration of 5% by mass to 30% by mass. The white toner according to any one of claims 1 to 7, wherein the resin A is a silicone-modified polyester. The white toner according to any one of claims 1 to 8, wherein the white pigment is titanium oxide particles or calcium titanate particles.