JPH07319316A - Full color image forming method - Google Patents

Abstract

PURPOSE:To form an image which does not give unnatural feeling to an image viewing side, to form an image part having gloss well-matched with the gloss of recording paper itself and to prevent the use purpose and the function of the recording paper from being hindered by restraining the difference of the glass between a non-image part and the image part. CONSTITUTION:In this full color image forming method, an expression holds in the case of assuming that the glossiness of an image supporting body is Gp(%), and the gloss part of the image part formed by transferring and fixing toner on the image supporting body is Gt (%).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method obtained by transferring a full-color image with a color toner onto an image support (hereinafter referred to as recording paper) and fixing the image.

[0002]

2. Description of the Related Art The glossiness of a copy image obtained by a full-color image forming method using color toners is an important factor in image quality. It is selected appropriately. For example, when it is used for the purpose of making a copy image of a monochrome character image, by using a low gloss recording paper, the specular reflection light on the surface of the copy image is reduced and the burden on the eyes is reduced. Readability is required. On the other hand, when it is used for the purpose of making a copy image of a color photograph, it is attempted to give a high quality and high quality image to the copy image by using a high gloss recording paper. Even in the image area formed by transferring and fixing toner on the surface of the recording paper, the same consideration should be given to the glossiness as the glossiness of the recording paper itself. It is necessary not to go against the quality. If the image area on the low-gloss recording paper has high gloss, it hinders readability. If the image area on the high-gloss recording paper is low gloss, the full-color copy is performed. The image becomes a poor image that is inferior in quality. In addition, in particular, in the case of a full-color image, increasing the surface glossiness is suitable for expanding the area of subtractive color mixture by toner, that is, providing a good color. Low gloss is not preferred.

As described above, the glossiness of the image portion is controlled in accordance with the glossiness of the recording paper to reduce the difference in glossiness between the non-image portion and the image portion, and the harmony is measured. Is not only a general "paper", but also OH
The same is required when forming an image on a P sheet. That is, the surface of the image area formed on the OHP sheet is made to be smooth with extremely high gloss like the surface of the non-image area, so that light scattering due to unevenness of the surface is suppressed and a good transmission color is obtained. Can be achieved.

As described above, the glossiness of the recording paper is selected according to the purpose of use of the user, and the purpose or function of the recording paper is a manifestation of the glossiness of the image portion formed on the surface of the recording paper. It is not preferable that it is far from its own gloss.

Further, in general, when there is a large difference between the glossiness of the non-image portion and the glossiness of the image portion of the recording paper, the low-gloss portion and the high-gloss portion are mixed in the same copy image. It is not preferable because it gives a psychological discomfort to the viewer.

With respect to the above-mentioned problem regarding the glossiness of the copied image, in the conventional full-color copying machine, the quality of the full-color image is generally emphasized, and the glossiness of the image portion is increased regardless of which recording paper is used. It was designed for. Therefore, the image portion formed on the low-gloss recording paper also has high glossiness, and the difference in glossiness between the non-image portion and the image portion is large, giving a viewer a psychological discomfort. . In particular, in the case of a copy image of a monochrome character image, since the character itself has high gloss, there is a problem that the character shines due to the specular reflection light and becomes difficult to read. For such a problem, for example, Japanese Patent Laid-Open No. 63-3
By designing the viscoelastic characteristics of the black toner when melted to be higher than that of the color toner as in No. 4, the gloss of the monochrome image portion (character image portion) is lowered and the color image portion is A technique for creating a copied image having high gloss has been proposed, but in this case, the fixing performance of the black toner and the color toner is greatly different, and therefore, the fixing conditions that can fix both toners satisfactorily. Becomes an extremely narrow range, and problems such as offset and insufficient fixing strength are likely to occur. Further, as another means, for example, JP-A-63-123
As disclosed in No. 055, a technique has been proposed in which transparent toner is fixed on the entire surface of a copied image to uniformize and control the glossiness, but a huge amount of transparent toner is consumed and a transparent toner development step is added. However, this causes problems such as complication of the device and reduction of copy productivity, and is not actually useful.

[0007]

DISCLOSURE OF THE INVENTION The present invention has been proposed in order to improve the above-mentioned problems in the prior art. That is, the present invention suppresses the difference in glossiness between the non-image area and the image area to form an image that does not give an uncomfortable feeling to the viewer of the image, and is glossy in harmony with the glossiness of the recording paper itself. The purpose is to form an image portion and not to impair the intended use, function, etc. of the recording paper.

[0008]

To achieve the above object, the present invention provides a method for forming a full-color image according to claim 1, wherein the glossiness of the image support is G _p (%). When G _t (%) is the glossy part of the image part formed by transferring and fixing toner on the body, the following relational expression

[0009]

[Equation 3]

[0010] is satisfied. The relational expression according to claim 2,

[0011]

[Equation 4]

Changing the temperature of the fixing roller and the fixing linear velocity is a means for satisfying the above condition. In Claim 3, it is achieved by forming an image on an image support using a toner in which the binder resin is insoluble in chloroform and the insoluble content is less than 30% by weight.

According to the present invention, the glossiness of the image support, that is, the recording paper is G _P (%),
The present invention proposes a full-color image forming method in which the following relational expression holds when the glossiness of an image portion formed by transferring and fixing toner on the recording paper is G _t (%).

[0014]

[Equation 5]

Here, the glossiness G _P (%) and G _t (%)
Is a numerical value that indicates the glossiness of the recording paper and image area according to JIS
-Use the value (%) measured by Method 2 of Z8741 (75 ° specular gloss). For the glossiness of the image area, a fixed image having a toner adhesion amount of 0.7 mg / cm ² on the recording paper is measured.
This is because when the glossiness is a problem, it is remarkable when the amount of adhered toner is large.

Then, by controlling the glossiness of the image portion so that the above relational expression is satisfied according to the glossiness of the recording paper itself, the difference in glossiness between the non-image portion and the image portion is suppressed to give an uncomfortable feeling. It is possible to obtain a full-color image that does not exist.

When the above relational expression is not satisfied, that is,

[0018]

[Equation 6]

In the case of, since the glossiness of the image portion is too low with respect to the glossiness of the recording paper, the image quality is poor and the image is poor, especially when a highly glossy recording paper is used. It becomes an image. In particular, when an OHP sheet is used as a recording paper, the smoothness of the image area becomes insufficient, and the color developability of the transmitted color deteriorates. vice versa,

[0020]

[Equation 7]

In the case of, the glossiness of the image portion is too high with respect to the glossiness of the recording paper, so that the characters in the monochrome character image shine due to specular reflection light, which makes it difficult to read. .

[0022]

Since the glossiness of the image portion is a manifestation of the fixing state in which the toner image formed on the recording paper surface is fixed, the glossiness depends on the viscoelastic characteristics of the toner, the mechanical structure of the fixing device, the fixing conditions, etc. Can change sex. In actual use in a copying machine, it is practically difficult to change the viscoelastic properties of the toner and the mechanical structure of the fixing device sequentially according to the passage of various glossy recording paper. A practical means is to control the glossiness of the image area by sequentially changing the conditions. Specifically, it suffices to change the roller temperature and the fixing linear velocity in a heat roller fixing device which is generally used as a fixing method in the electrophotographic method according to the glossiness of the recording paper. In this case, the glossiness of the image portion correlates with the amount of heat of fixing heat applied to the toner, and therefore the roller temperature is increased and / or the fixing linear velocity is decreased to lengthen the heating time for high gloss. On the contrary, in order to obtain a low gloss, the roller temperature is lowered, and / or the fixing linear velocity is increased to shorten the heating time. Even in this case, changing the roller temperature is accompanied by a waiting time for raising or lowering the temperature. Therefore, it is most preferable to control the glossiness of the image only by changing the fixing linear velocity because the waiting time is not required.

In order to achieve the present invention by the above actions, no restrictions are imposed on the viscoelastic properties of the toner and the mechanical structure of the fixing device, but the variable range of the glossiness of the image is made wide. Further, a more preferable use form for facilitating the controllability will be described below.

First, as a color toner for image formation, its viscoelastic property should be most considered, but as a viscoelastic property that facilitates achievement of the present invention, a conventional full color image forming toner is used. It is particularly preferable to have a design with emphasis on offset resistance since it has a higher elasticity and the latitude for a wide range of fixing conditions for changing the glossiness becomes wide.

As the binder resin of the toner, one having a partially crosslinked molecular structure is particularly preferable as compared with the non-crosslinked resin structure in order to exhibit the above viscoelastic properties.
In this case, the crosslinking degree is preferably less than 30% by weight in terms of chloroform-insoluble matter in the binder resin of the toner. When the content of chloroform insolubles is 30% by weight or more, it is difficult to control the glossiness because the elasticity of the toner when melted is too high.

The chloroform-insoluble matter is measured by the following method.

The binder resin was finely pulverized and 5.00 g of a sample passed through a 40-mesh sieve was collected and put in a container together with 5.00 g of filter aid Radiolite (# 700), and 100 g of chloroform was injected into the container. After that, the sample is placed on a ball mill stand and rotated for 5 hours or more to sufficiently dissolve the sample in chloroform. On the other hand, a filter paper having a diameter of 70 mm is laid in the pressure filter, 5.00 g of radiolite is uniformly pre-coated on the filter paper, and a small amount of chloroform is added to bring the filter into close contact with the filter.
Next, the contents of the container are poured into the filter while thoroughly washing the wall surface deposits in the container with chloroform, and then the filter lid is closed and filtration is performed under a pressure of 4 kg / cm ² or less. After the outflow of chloroform has stopped, new chloroform is added to wash the residue on the filter paper, and pressure filtration is performed again. After the above operation is completed, put the filter paper in the filter, the residue on the filter paper, and the radiolite all on a Petri dish and put in the vacuum dryer. Temperature 80 ~ 100 ℃, pressure 100 mmHg
Total weight of dry solid obtained by drying for 10 hours under the conditions of
(G) is measured, and the chloroform insoluble content Z (% by weight) is calculated by the following formula.

[0028]

[Equation 8]

The chemical structure of the binder resin can be selected from a general range including conventionally known ones. Specific examples of the binder resin include
Examples thereof include styrene, acrylic acid and its ester compound, methacrylic acid and its ester compound, homopolymers or copolymers of acrylonitrile and the like, polyester, polyurethane and polyamide.

As a constituent material of the toner, a coloring agent, a release agent, a charge control agent, which are required in addition to the binder resin,
With regard to materials such as external additives and lubricants, those widely used in general can be selected and used.

Specific examples of the colorant include carbon black and nigrosine dye as the black colorant. CI Pigment Yellow No.12,13,14,15, which is a benzidine yellow pigment as a yellow colorant.
17, 55, 83, 174 etc. can be mentioned. CIPi, a quinacridone-based magenta pigment, as a magenta colorant
gment Red No.122, C. which is an azo lake magenta pigment.
I.Pigment Red No.57-1 etc. can be mentioned. CI Pigmen, a copper phthalocyanine pigment as a cyan colorant
t Blue No.15, 15-3, 15-4, 15-6 etc. can be mentioned.

Specific examples of the releasing agent include low molecular weight polyethylene, low molecular weight polypropylene, amide wax, polyhydric alcohol ester and the like.

The charge control agent, which constitutes a part of the color toner, is preferably colorless or white, and specific examples thereof include salicylic acid or a zinc salt of a salicylic acid derivative.

Specific examples of the external additive include inorganic particles such as silica, alumina and titania, organic particles such as silicone resin particles and fluorine resin particles, and lubricants such as metal salts of higher fatty acids.

As the fixing device, for example, LT is provided on the surface of the heat fixing upper roller on the side where the toner layer on the recording paper comes into direct contact.
It is preferable to use a roller having elasticity such as a V rubber layer. That is, when the surface of the heat fixing upper roller has elasticity, the surface of the heat fixing upper roller itself deforms and presses against the unevenness of the unfixed toner image surface, so that the toner image is uniformly heated. It is possible to pressurize and widen the variable range of glossiness. In this case, the elasticity of the surface of the heat fixing upper roller preferably has a hardness of 50 ° or more and 85 ° or less. When the hardness is less than 50 °, the amount of deformation of the surface of the heat fixing upper roller becomes excessive, which causes a problem in the paper passing property of the recording paper. When the hardness is higher than 85 °, the deformation of the surface of the heat fixing upper roller becomes insufficient, and it becomes impossible to uniformly heat the toner layer. Further, the pressure-bonding lower roller, which is pressure-bonded to the heat-fixing upper roller through the recording paper, has a hardness of the surface of the heat-fixing roller so that the surface of the unfixed toner image is sufficiently pressed against the surface of the heat-fixing upper roller. The hardness is preferably the same as or higher than the hardness of the surface of the working roller. In order to impart elasticity of appropriate hardness as described above to the surfaces of the heat fixing upper roller and the pressure bonding lower roller, an elastic rubber layer made of, for example, silicone rubber or fluororubber may be provided on the roller surfaces. The hardness of the roller surface is measured by an Asker C hardness meter. Furthermore, for the purpose of preventing offset, the surface of the heat fixing upper roller is polyvinylidene fluoride (PV
F), polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA) or the like is preferably provided with a low surface energy coating layer and / or silicone oil is preferably applied. .

[0036]

EXAMPLES Specific examples of this example will be described below, but these examples do not limit the present invention. In addition, "parts" in the examples mean "parts by weight".

Color toner 1 (K1, Y1, M1, C
The production method of 1) is as follows: 100 parts of a polyester resin, which is a polycondensate composed of bisphenol A / propylene oxide, terephthalic acid and trimellitic acid as a binder resin and has an insoluble content in chloroform of 10% by weight,
10 parts of carbon black as a colorant and 3 parts of a low molecular weight polypropylene wax as a release agent were mixed, then melt-kneaded and pulverized and classified to obtain colored particles having a volume average particle diameter of 8.5 μm. Next, to 100 parts of the colored particles, 0.5 part of hydrophobic silica and 1.0 part of hydrophobic titania were added and mixed to prepare a black toner K1 which is an example of the present invention.

Similar to the production of K1, as a colorant, instead of carbon black, as a yellow pigment, CI Pigment Ye
Yellow toner Y1 which is an example of the present invention was obtained by using 8 parts of Low No. 17: 8.

In the same manner as in the production of K1, carbon black was used as the colorant, and CI Pigment Red was used as the magenta pigment.
No. 122: Magenta toner M1 which is an example of the present invention was obtained by using 8 parts.

Similar to the production of K1, CIPigment Blue was used as a cyan pigment instead of carbon black as a colorant.
No. 15-3: Cyan toner C1 which is an example of the present invention was obtained by using 4 parts.

Color toner 2 (K2, Y2, M2, C
The production method of 2) is the same as in the production of the color toner 1 except that the binder resin is changed to a polyester resin which is a polycondensation product of bisphenol A.propylene oxide and fumaric acid. A black toner K2, a yellow toner Y2, a magenta toner M2, and a cyan toner C2 were obtained.

The above toner has a styrene-methylmethacrylate resin coating layer on the surface and has a volume average particle diameter of 45 μm.
A ferrite core carrier of m was mixed so that the toner concentration would be 7% by weight and used as a two-component developer.

A copied image was output using the above-mentioned developer, and evaluated and compared. For image output, the Konica modified the fixing device to the configuration shown in FIG.
A full-color copying machine "DC9028" manufactured by Co., Ltd. was used. That is, in FIG. 1, the toner T is fixed on the recording paper P,
The fixed image T ₁ is formed. Reference numeral 1 is a heater lamp, which is a halogen lamp (600 W) and is fixedly incorporated through a hollow aluminum roller 2 having a diameter of 40 mm. An upper heat fixing roller 7 having an LTV rubber layer 3 and a PFA tube layer 4 formed on the surface of the hollow aluminum roller 2, and an LTV rubber layer 31 and a PFA tube layer 41 formed on the surface of a hollow aluminum roller 21 having a diameter of 40 mm. And a pressure-bonded lower roller 71.
The heat fixing upper roller 7 is provided with a cleaning roller 5 and an oil application roller 6 impregnated with silicone oil.

The surface temperature of the heat fixing upper roller 7 and the fixing linear velocity are controlled by the CPU in accordance with the glossiness of the recording paper P and the viscoelastic characteristics of the toner T. In the evaluation and comparison, the heat-fixing upper roller 7 and the pressure-bonding lower roller of the fixing device are used.
A combination of 71 surface hardnesses as shown in Table 1 was prepared and used.

[0045]

[Table 1]

By using the above-mentioned full-color toners 1 and 2 and the fixing devices 1, 2 and 3 shown in Table 1, the surface temperature and the fixing linear velocity of the heat fixing roller of the fixing device are controlled to obtain recording paper. A copy image was created using high-quality paper, art paper, and OHP sheet. With respect to the obtained copy image, the glossiness of each recording sheet; G _p (%), and the glossiness of the image portion fixed on the recording sheet; G _t (%) were measured. Further, the following evaluation was carried out in relation to the glossiness of the image area according to the type of each recording paper.

(A) When high-quality paper is used as the recording paper.

As the evaluation of the readability of the monochrome character image fixed on the high-quality paper, the following three-stage judgment was made by visual judgment.

◯: The light of characters due to regular reflection is not felt at all, and the reading of a document does not feel any discomfort.

Δ: Character light due to specular reflection can be sensed when viewed from an oblique direction with an incident angle of 60 ° or more, but there is no problem in reading a document.

X: The light of characters due to regular reflection is clearly felt, and the position of the light source is anxious when reading a document.

(B) When art paper is used as the recording paper.

[0053]

[Outer 1]

(C) When an OHP sheet is used as the recording paper.

As an evaluation of the color developability in the projection image of the full-color image fixed on the OHP sheet on the OHP sheet, for the yellow, magenta, and cyan single-color image areas where the toner adhesion amount is 0.7 mg / cm ^2. , The transmittance spectrum of the transmitted color was measured by "330 type self-recording spectrophotometer" manufactured by Hitachi, Ltd., and the transmittance at the transmission part and the absorption part; Δ% T
(%) Was calculated by the following formula.

Yellow single color image portion: Δ% T =% T (650n
m)-% T (450nm) Magenta monochromatic image area; Δ% T =% T (650nm)-% T (550n
m) Cyan monochromatic image area; Δ% T =% T (500 nm) −% T (600 nm) As described above, the higher the value of Δ% T, the better the color development in the OHP projection image.

The evaluation results obtained as described above are shown in Table 2 below.
Indicate.

[0058]

[Table 2]

That is, Examples 1, 4, 7, 10, 1 in Table 2
The copied images created in 3 and 16 are comparative examples 1, 4, 7, and 1.
Compared to 0, 13, and 16, the light of characters due to regular reflection is less in the monochrome character image, and the burden on the eyes is reduced,
It was easy to read.

The copied images prepared in Examples 2, 5, 8, 11, 14, and 17 are compared with Comparative Examples 1, 5, 8, 11, 14, and 17 in the full-color image. It exhibited high glossiness over a long period of time, and was full of high-grade feeling and high-quality images. In particular, due to its high glossiness, it exhibited a wide coloring area.

Compared with Comparative Examples 3, 6, 9, 12, 15, and 18, the copied images prepared in Examples 3, 6, 9, 12, 15, and 18 have sharper projected images at OHP. It showed a color.

[0062]

As described above, according to the present invention, as shown in Examples 1 to 18, the temperature of the heat fixing upper roller and the fixing linear velocity are changed according to the glossiness of the recording paper to change the glossiness of the image area. By controlling the glossiness of the non-image area and the image area in the copied image, the difference in the glossiness between the non-image area and the image area is small, and the glossiness of the image area is less than that of the recording paper. It has become possible to obtain a copied image that does not impede the purpose and required tasks.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing device used in the present invention.

[Explanation of symbols] 1 heater lamp 2,21 hollow aluminum roller 3,31 LTV rubber layer 4,41 PFA tube layer 5 cleaning roller 6 oil application roller 7 heat fixing upper roller 71 pressure bonding lower roller

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 15/01 J

Claims (3)

[Claims] 1. In a full-color image forming method, the glossiness of an image support is G _p (%), and the glossy part of an image portion formed by transferring and fixing toner on the image support is G _p (%). _{When t} (%), the following relational expression A full-color image forming method, characterized in that 2. The relational expression: 2. The full-color image forming method according to claim 1, wherein the temperature of the fixing roller and the fixing linear velocity are changed as means for satisfying the above condition. 3. An image is formed on an image support using a toner in which the binder resin is insoluble in chloroform and the insoluble content is less than 30% by weight.
2 is a full-color image forming method.