JP3277742B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic transfer paper for obtaining a high-quality copy and an image forming method using toner.

[0002]

2. Description of the Related Art Hitherto, in order to obtain a high quality image by electrophotographic copying, it has been practiced to reduce the particle size of toner to improve the graininess. In order to further reduce the granularity of the toner, attempts have been made to reduce the amount of toner (g / cm ² ) fixed on the transfer paper by increasing the content of the colorant in the toner and the like. Also, in order to obtain high-quality images as in flat plate offset printing, electrophotographic methods also use surface-coated paper such as art paper or coated paper, in which case conventional electrophotographic methods are used. As compared with rough paper used in the method, an image is faithfully reproduced, and image quality of a copied image is improved, such as an increase in image gloss, a decrease in gloss unevenness, and an improvement in color reproducibility. For example, Japanese Patent Publication No. 5-82939 and Japanese Patent Publication No.
JP-A-82940 describes a coated paper which has been coated with a paint containing a pigment having an average particle size of 1.5 μm or less and subjected to a smoothing treatment.

[0003] By the way, using the above-mentioned smooth coated paper and using a toner having a diameter smaller than the printing dot as a developer,
Even if an image is formed by electrophotography using a small amount of fixing toner (g / cm ² ) and using a high gloss toner,
It was not possible to obtain an image equivalent to high quality print quality on coated paper as in flat plate offset printing. Considering the reason, as one of the major reasons, in flat plate offset printing, the ink used permeates on paper, whereas in the case of electrophotographic toner, since it has a solid volume, even after heat fixing, It is considered that the toner forms a convex image on the smooth coated paper surface, and irregular surface reflection occurs, and this is sensed as noise, so that the image has an appearance different from that of printing.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to prevent the occurrence of image quality defects in the conventional electrophotographic method. That is, the object of the present invention is:
An object of the present invention is to provide an image forming method capable of obtaining a high-quality copy image in which a convex image is not formed by toner even after toner fixing.

[0005]

The image forming method of the present invention According to an aspect of the toner image which has been visualized on the latent image bearing member, electrophotographic transfer comprising only set the <br/> resin layer on the base paper It has a process of transferring and fixing on paper, and the toner itself has a temperature of 150 ° C.
When the storage modulus at 150 ° C. of the resin on the transfer paper surface is G′2 and the storage elastic modulus at 150 ° C. is G′2, the toner image is transferred and fixed under the conditions satisfying the following equation. I do. G'1 -15≤G'2≤G'1 + 150

Hereinafter, the present invention will be described in detail. In the present invention, as the latent image carrier, any material that can carry an electrostatic latent image, such as a photoreceptor or a dielectric recording material used in electrophotography, can be used. . The electrostatic latent image is formed by a well-known method,
The toner image is formed by toner to form a toner image, and then transferred onto an electrophotographic transfer paper.

[0007] The electrophotographic transfer paper is obtained by providing a resin layer on a base paper, and the resin layer is preferably transparent. The resin layer has a solubility parameter (SP value) of 1
It is preferably made of a resin having a storage elastic modulus (G'2) of 10 to 200 Pa at 0 to 13 and 150 ° C. When the storage elastic modulus of the resin layer is lower than 10 Pa, offset of the resin layer occurs at the time of fixing, and when the storage elastic modulus is higher than 200 Pa, the toner does not penetrate into the resin layer even after fixing, and a convex image is generated. Become like The storage elastic modulus is a certain temperature, a certain angular frequency ω
Is defined as the elastic term of the viscoelastic function of the substance, and indicates the degree of elasticity of the resin itself at that temperature. The value can be determined with a rotary rheometer [Dynamic Analyzer RDAII (Rheometrics)].

Examples of the resin constituting the resin layer include polyester resin, styrene-acrylate resin, styrene-methacrylate resin, etc., and polyester resin is particularly preferably used. Examples of the polyhydric alcohol component and the polyhydric carboxylic acid component constituting the polyester resin include the following.

The polyhydric alcohol component includes ethylene glycol, propylene glycol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, Neopentylene glycol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, bisphenol A, hydrogenated bisphenol A, and the like can be used. Among these, bisphenol A, derivatives thereof, alkylene oxide adducts thereof, hydrogenated bisphenol A and the like are preferable, and bisphenol A derivatives represented by the following formula (I) are particularly preferable.

[0010]

Embedded image (In the formula, R ¹ and R ² each represent an ethylene group or a propylene group, a and b are each an integer, and the sum of both is 2 to 7.) Specific examples thereof include polyoxypropylene ( 6) -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 and the like.
Glycerin, sorbitol, 1,4-sorbitan, trimethylolpropane, and the like can be used as the trihydric or higher alcohol component.

Examples of the polycarboxylic acid component include maleic acid, maleic anhydride, fumaric acid, phthalic acid, terephthalic acid, isophthalic acid, malonic acid, succinic acid, glutaric acid, dodecenyl succinic acid, n-octyl succinic acid, n
-Dodecenyl succinic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid,
1,2,4-naphthalenetricarboxylic acid, 1,2,5-
Hexanetricarboxylic acid, 1,3-dicarboxy-2-
Methyl-2-methylenecarboxypropane, tetra (methylenecarboxy) methane, 1,2,7,8-octanetetracarboxylic acid, trimellitic acid, pyromellitic acid and lower alkyl esters of these acids can be used.

The resin layer may contain a pigment, a release agent and the like as far as the transparency is not impaired. Even in such a case, the amount of the resin must be 80% by weight or more.
The electrophotographic transfer paper of the present invention can be produced by applying a resin solution to one or both sides of a base paper to form a resin layer, and then subjecting the surface to a smoothing treatment. The smoothing treatment of the resin layer after application can be performed by passing a nip between a rigid roll and an elastic roll many times, such as a super calender or a gloss calender. In the smoothing process, the center line average roughness according to JIS B0601 is set to 2.
It is preferable to adjust the thickness to be 0 μm or less, particularly 1.5 μm or less.

In this case, it is preferable that the standard deviation of the coefficient of static friction between the sheets in the deposited state is adjusted to 0.05 or less, or the air permeability is adjusted to 4000 seconds or less. Further, it is preferable that the resin layer is adjusted to have a surface resistance of 8.0 × 10 ⁸ Ω or more at a temperature of 20 ° C. and a relative humidity of 85%. In order to impart air permeability to the resin layer, a pigment having a small average particle size and a large oil absorption may be blended. For example, the average particle size is 1.5 μm or less, preferably 1.0 μm.
m or less, calcium carbonate, silica, calcined clay, aluminum hydroxide, lithopone, zinc oxide, titanium dioxide,
Barium sulfate or the like can be used. In the transfer paper for electrophotography according to the present invention, the resin layer may be provided on both sides of the base paper. As a coating method, a commonly used method, for example, blade coating, air knife coating, roll coating, bar coating, or the like can be applied. The thickness of the resin layer varies depending on the particle size of the toner to be fixed, but is generally preferably in the range of 3 to 20 μm.

An adhesive layer is provided between the transparent layer and the base paper.
Alternatively, a pigment layer for smoothing may be provided. Examples of the pigment include calcium carbonate, silica, calcined clay, aluminum hydroxide, lithopone, zinc oxide, titanium dioxide, barium sulfate and the like. These pigments are
It is desirable that the average particle size is 1.5 μm or less. As an adhesive used for the adhesive layer or the pigment layer, a base paper, a water-soluble polymer having a strong adhesive force to a pigment and the like, and having a low blocking property, for example, polyvinyl alcohol, starch, methyl cellulose, hydroxyethyl cellulose, styrene-acryl resin, Isobutylene-maleic anhydride resin, water-soluble resin such as carboxymethyl cellulose, acrylic resin emulsion, vinyl acetate resin emulsion,
A vinylidene chloride resin emulsion, a polyester resin emulsion, a styrene-butadiene copolymer latex, an acrylonitrile-butadiene copolymer latex, or the like can be used. The pigment layer can be formed by applying a coating liquid in which the pigment and the adhesive are mixed at a mixing ratio of 95: 5 to 60:40.

On the other hand, the toner used in the present invention is:
It is composed mainly of a colorant and a binder resin. In the present invention, as the colorant to be contained in the binder resin, any known colorant can be used.
For example, carbon black, aniline blue, calcoil blue, chrome yellow, ultramarine blue, Dupont oil red, quinoline yellow, methylene blue chloride, phthalocyanine blue, malachite green oxalate, lamp black, rose bengal,
C. I. Pigment Red 48: 1, C.I. I. Pigment Red 122, C.I. I. Pigment Red 5
7: 1, C.I. I. Pigment Yellow 97, C.I. I.
Pigment Yellow 12, C.I. I. Pigment Yellow 17, C.I. I. Pigment Blue 15: 1, C.I.
I. Pigment Blue 15: 3 can be exemplified as a typical example. The content of the coloring agent is preferably in the range of 2% by weight to 8% by weight. When the content of the coloring agent is less than 2% by weight, the coloring power is weakened, and when it is more than 8% by weight, the transparency of the color toner is deteriorated.

The binder resins used in the present invention include styrenes such as styrene and chlorostyrene, monoolefins such as ethylene, propylene, butylene and isoprene, vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate. Vinyl esters, methyl acrylate, ethyl acrylate, butyl acrylate, dodecyl acrylate, octyl acrylate, phenyl acrylate,
Α-methylene aliphatic monocarboxylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, dodecyl methacrylate, vinyl methyl ether,
Homopolymers and copolymers such as vinyl ethers such as vinyl ethyl ether and vinyl butyl ether, and vinyl ketones such as vinyl methyl ketone, vinyl hexyl ketone and vinyl isopropenyl ketone can be exemplified. Particularly typical binder resins include polystyrene resin, polyester resin, styrene-alkyl acrylate copolymer, styrene-alkyl methacrylate copolymer,
Styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer,
Examples include polyethylene resin and polypropylene resin. Further, polyurethane resins, epoxy resins, silicone resins, polyamide resins, modified rosins, paraffins, waxes and the like can be mentioned. Among these resins, it is particularly preferable to use the same type of polyester resin as that used for the resin layer of the transfer paper. In the present invention, the binder resin preferably has a storage modulus of 10 to 300 Pa measured at 150 ° C. at an angular frequency of 10 rad / sec.

The toner according to the present invention comprises the above colorant and the binder resin as main components, and those having an average particle size in the range of 3 to 15 μm, particularly 5 to 10 μm are preferably used. You. Also, the temperature of the toner itself is
Storage elastic modulus G'1 (angular frequency 10 rad / se)
c) is preferably in the range of 10 to 200 Pa.

Further, an external additive may be added to the toner. As the external additive, inorganic compound fine powder and organic compound fine particles are used. The inorganic compound fine particles are SiO ₂ ,
TiO ₂ , Al ₂ O ₃ , CuO, ZnO, SnO ₂ , F
e ₂ O ₃ , MgO, BaO, CaO, K ₂ O, Na
₂ O, ZrO ₂ , CaO.SiO ₂ , K ₂ O. (TiO
₂ ) _n , Al ₂ O ₃ .2SiO ₂ , CaCO ₃ , MgC
O ₃ , BaSO ₄ , MgSO _{4 and the} like can be exemplified. Examples of the organic compound fine particles include fine powders of fatty acids or derivatives thereof, metal salts thereof, and the like, and fine resin powders such as fluororesins, polyethylene resins, and acrylic resins.

In the present invention, a toner image formed by using the above toner is transferred to the above electrophotographic transfer paper,
At the time of fixing, when the storage elastic modulus at 150 ° C. of the toner itself is G′1 and the storage elastic modulus at 150 ° C. of the resin on the surface of the transfer paper is G′2, the condition satisfying the following expression (1) is satisfied. It is necessary to carry out transfer and fixing. G′1 −15 ≦ G′2 ≦ G′1 +150 (1) Preferably, the range satisfies the following expression (2). G'1 .ltoreq.G'2 .ltoreq.G'1 +50 (2) If the value of G'2 is within the range of the above formula (1), a smooth copy without a convex image can be obtained after fixing. Also,
If the value of G'2 is within the range of the above equation (2), it is obvious that the copy after fixing is smooth without a convex image.
It is more preferable because it has excellent compatibility with adjacent toner and color mixing property, and provides a sharp image. That is, the above equation (1)
When the condition (1) is satisfied, the surfaces of the toner and the resin layer are melted at the time of fixing, and the toner enters the resin layer and solidifies, thereby forming a smooth surface after the fixing. If the value of G'2 is smaller than G'1 -15, the compatibility with the adjacent toner is reduced, resulting in an image having poor color mixing. If the value of G'2 is larger than G'1 +150, the image is transferred during fixing. The toner cannot enter the resin on the surface of the paper, resulting in an image having irregularities and deteriorating the image quality.

[0020]

EXAMPLE 50 g / m2 of paper made by adding 100 parts by weight of bleached hardwood kraft pulp having a beating degree of 530 cc, 10 parts by weight of clay, 2 parts by weight of starch, 1.5 parts by weight of a rosin sizing agent and 1 part by weight of a sulfuric acid band. Table 1 using ^two high quality papers
A coating solution obtained by dissolving the resin described in above in toluene was applied to one surface of the high-quality paper using a blade coater, and then subjected to a smoothing treatment using a super calender to obtain a film
Thus, a copy paper having a resin layer of m was formed.

On the other hand, as a toner, the resins shown in Table 1 were used as a binder resin, and 95 parts by weight thereof were used as C.I. I. 5 parts by weight of CI Pigment Red 57: 1 by a Banbury mixer, pulverized by a jet mill, and classified. 5% of particles having a particle diameter of 7 μm and 4 μm (pop) or less is 5%, 16 μm (v
ol) to obtain a 0.1% toner. Further, 2 parts by weight of titanium oxide (10% triethoxydecylsilane treatment) having an average particle diameter of 20 nm was added to 100 parts by weight of the toner, and mixed with a Henschel mixer to obtain a toner. Table 2 shows the storage modulus G'1 of the toner itself.

[0022]

[Table 1] Further, a developer obtained by coating ferrite particles having an average particle diameter of 50 μm with a 1.0% styrene acrylic resin coating as a carrier and mixing the toner with the above toner at a ratio of 100: 10 was obtained.

Using the developer obtained as described above,
Copying was performed by a copying machine (A-Color 635), and the image quality of the obtained copied image was evaluated. Table 2 shows the results. In Table 2, the offset was evaluated by observing the adhesion of the resin layer to the second copy. The evaluation criteria are as follows. ○:
No adhesion, ×: Adhered. The smoothness of the resin layer surface is determined by JI
Judgment was made based on the center line average roughness of the surface according to SB0601. The evaluation criteria are as follows. ：: 2.0 μm
Less than: Δ: 2.0 μm or more and 3.0 μm or less, ×: More than 3.0 μm. The sharpness of the character image was determined by visual observation of the size of Japanese text. The evaluation criteria are as follows. ○: 4-point Japanese text is legible,
Δ: 6-point Japanese text is legible, ×: 6-point Japanese text is not legible. The evaluation criteria for the overall image quality are as follows. ：: excellent over all, △: usable, ×: inferior.

[0024]

[Table 2]

[0025]

As described above, according to the present invention, when a toner image is transferred and fixed to an electrophotographic transfer paper having a resin layer provided on a base paper, the storage elastic modulus of the toner itself and the storage of the resin layer are determined. Since the transfer and fixing are performed such that the elastic modulus is set within the specific range described above, a sharp image is formed because a convex image is not formed on the paper surface and scattering of reflected light is suppressed. Is obtained.

Continuation of the front page (72) Inventor Kiyoshi Hosoi 2274 Hongo, Ebina-shi, Kanagawa Fuji Xerox Co., Ltd. (56) References JP-A-2-263642 (JP, A) JP-A-2-26362 (JP, A JP-A-6-175395 (JP, A) JP-A-6-506307 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/16 101 G03G 7/00 101 G03G 9/08 G03G 15/20 101

Claims (2)

(57) [Claims] [Claim 1] transferring the toner image on the electrophotographic transfer paper comprising a resin layer set only on the base paper, in an image forming method having the step of fixing, the storage modulus at 0.99 ° C. of the toner itself G ' 1 and 150 ° C of the resin on the transfer paper surface
An image forming method wherein a toner image is transferred and fixed under the conditions satisfying the following equation, where the storage elastic modulus is G'2. G'1 -15≤G'2≤G'1 + 150 2. A solubility parameter (SP value) of 10 to 13 and a storage modulus (G'2) at 150 ° C. of 1
The image forming method according to claim 1, wherein an electrophotographic transfer paper having a resin layer made of a resin having 0 to 200 Pa provided on a base paper is used.