JPS59172659A - Polychromatic picture formation - Google Patents

Abstract

PURPOSE:To obtain a picture in the 2nd color which is not influenced by the color of a background by forming a picture of a toner layer in the 2nd color with high hiding power on the 1st picture or a colored base. CONSTITUTION:An electrostatic latent image formed by an electrostatic photographing method is formed on a picture base which has a picture in the 2nd color obtained by being developed by toner which has the 2nd color and <=0.6 hiding power and a picture in the 1st color at least partially, and fixation is carried out to attain the purpose. The amount of a coloring agent in the toner is increased to set the hiding power of the color toner to <=0.6 effectively, and the addition of material which has a >=0.6, preferably, >=0.2 refractive index is specially effective.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improved multicolor image forming system using electrostatic recording, and more specifically, to an improved multicolor image forming system suitable for forming so-called functional color images. The present invention relates to an image forming method.

[Prior art]

To record color images using electrostatic recording, one method of color copying is generally used, which reproduces the colors of the original image by combining three-color separation exposure and subtractive affi color (or four colors including black) color toner. However, apart from that, it is useful to display specific characters, figures, graphs, etc. on the screen using colors other than the commonly used dot colors, or to use an image support that has been colored with % compression to help identify and emphasize them. There is a so-called functional color system that gives C1 or a special meaning. Functional color methods do not reproduce natural colors as they are, but due to the free use of colors, they can record a much larger amount of information than monochromatic recordings, and depending on the purpose, they can be used as color recordings to reproduce original paintings. can be used as another powerful means of expressing information.

In the conventional color image forming method using the subtractive color method, toners of three primary colors or four colors, including black, are overprinted in a single layer to produce a large number of (intermediate) colors. On the other hand, with functional color, the purpose is to distinguish by color, and there is no need to express intermediate colors by mixing colors. There are various ways to use it, such as overprinting a second color image on a ready-made object printed with various characters, figures, forms, grids, etc. In any case, the second color image is It is necessary to exhibit clear coloring without being affected by the first color that serves as the base.

Conventional image forming methods using highly transparent color toners have the disadvantage that overprinted images transmit the underlying color and do not provide the clear colors required for functional color copying.

[Purpose of the invention]

The object of the present invention is to ensure that the second color image formed on the image support is not affected by the underlying image or the first color applied to the image support (so that the image has a clear coloration). It is an object of the present invention to provide a color image forming method suitable for functional color that maintains the image quality.

[Structure of the invention]

The above object is to develop an electrostatic latent image formed by electrostatic photography using a toner having a second color and an opacity of 0.6 or less to obtain an image of the second color. This was achieved by forming an image on an image support having a first color, or at least a portion of the image is colored in the first color, and then fixing the image.

The hiding power of the above toner is measured as follows and is a value of t.

(Measurement of Concealability) 25 g of the toner to be tested is dissolved in 150 g of trimethyl ethyl chloride, and the solution is coated onto a 100 μm thick polyester film using a wire bar to give a dry film thickness of 10 to 15 μm and dried.

The dried sample was placed in close contact with a glossy white board with a reflection density of 0.12 and a glossy black board with a reflection density of 2.04, and measured without using a filter using a Sakura PDA-65 type reflection densitometer (manufactured by Konishiroku Photo Industry ■). The respective reflection densities Dw and DB are measured. At the same time, the dry film thickness d (unit: μm) of each sample is measured, and the hiding property H is defined by the following formula.

H= (DB - Dw) X 10/d Therefore H
The smaller the value, the higher the concealment.

The color toner used in the method of the present invention may have the above-mentioned hiding power of 0.6 or less, and its composition is not particularly limited, but may include toner copolymers, olefin-vinyl acetate copolymers, etc. Known synthetic resins commonly used in electrostatic recording toners, such as polymers, epoxy resins, polyester resins, polyolefins, and styrene-butadiene copolymers, are used, and as colorants, various organic pigments, dyes, and inorganic pigments are used. Although pigments can be used, it is preferable to use organic pigments such as monoazo, azo lake, condensed azo, and polycyclic pigments, or dyes such as azo dyes, anthraquinone dyes, and phthalocyanine dyes.

Other color toners used in the method of the present invention include various charge control agents, hydrophobic silica, fatty acid metal salts, and other substances that improve the fluidity and cleanability of the toner, or polyethylene, polypyrene, wax, etc. Various additives commonly used in toners, such as those that improve the fixing properties of toners, can also be added.

The opacity of the color toner used in the method of the present invention is 0.
．． In order to make it 6 or less, it is effective to increase the amount of colorant in the toner, but it is also effective to add a substance with a refractive index of 1.6 or more, particularly preferably 2.0 or more, to the toner. Particularly effective. Refractive index 1.6 used for the above purpose
Preferred examples of the above substances include white pigments such as titanium oxide, zinc oxide, antimony oxide, tin oxide, zirconium oxide, zinc sulfide, barium sulfate, and lithopone.

The toner used in the method of the present invention can be manufactured by a conventional toner manufacturing method in which the above-mentioned raw materials are mixed, mixed with a melting wire, cooled, and then crushed and classified.

In order to obtain a multicolor record by the method of the present invention, a normal monochrome electrostatic recording device is loaded with the following color toners with an opacity of 0.6 or less, and a ready-made copy, printed matter, colored paper, etc. is image-supported. It is sufficient to form an image as a body, and various known multicolor electrostatic recording devices, such as Japanese Patent Application Laid-Open No. 56-25751, are used.
Image formation may be performed by loading a plurality of toners using an apparatus such as that disclosed in the above publication.

[Function and effect of the invention]

In conventional methods that use highly transparent color toners, in areas where images overlap, the color of the first image that serves as the base passes through the color of the second image formed on top of it, resulting in a mixed and unclear color. However, according to the method of the present invention, a second image having a high hiding property is formed on the first image or the colored support.
Since an image consisting of a single layer of toner of a color is formed, it is possible to obtain a second color image that maintains a clear color without being affected by the underlying first image or the color of the support. can.

This will be explained below using examples.

[Example 1] A red toner was experimentally produced using the following formulation. (Numbers in the prescription indicate parts by weight.) Sample A Inm ■ Synthetic resin 1) 100 100 100 10
0 red pigment 2) 0.5 1 5
Titanium trioxide - -0,091)
Styrene/methyl methacrylate/butyl methacrylate composition ratio 50:20:300 copolymer 2) Chromophthalene, ) BRN (manufactured by Cibasha Geigy) Condensed azo organic pigment For each sample, the above materials were mixed in a ball mill for 10 hours. The mixture was melted and kneaded using a two-screw extruder (PCM-30 manufactured by Ikegai Iron Works Co., Ltd.), and after cooling, it was pulverized using a jet pulverizer and classified to obtain four types of trial toners having an average particle size of 11 to 12 μm.

Furthermore, carrier (DSP-135,
(manufactured by Dowa Iron Powder Co., Ltd.) were mixed and stirred to obtain four types of developers.

These developers are transferred to an electrostatic copier U-Bix 3000.
(manufactured by Nishiroku Photo Industry ■), and a practical test was conducted using a lattice pattern with a width of 1 cIrL as an original. In order to observe the influence of the color of the base, white paper and black paper were used as image supports, and the color of the formed red image was visually evaluated. In parallel with this, the hiding properties (H) of each toner were measured according to the method described above.

The test results are shown in Table 1.

Table 1 Sample A I II III I
V Color development on white paper ○ ○ ○ ○ Color development on black paper Me Δ× ○ ○HO
, 710, 640, 450, 39 A red image was obtained.

[Example 2] A yellow toner was prototyped using the following formulation.

Sample A VVI Synthetic resin 1) 100 100 Organic pigment 2) 33 Titanium oxide 0.09 -1) Copolymer of styrene/butyl methacrylate composition ratio 85:15 2) Two types of Sumitone Fast Yellow HRT toners were obtained. Two types of developers were prepared by thoroughly mixing 24 g of each toner and 1186 g of a spherical carrier coated with a copolymer of methyl methacrylate/styrene (composition ratio 70/30). A practical experiment was conducted.

First, a normal black toner was loaded into a copying machine, and three copies were made on white paper using a chart having 1 cm wide vertical black stripes as an original. Next, using the same type of copying machine loaded with the above prototype yellow toner, a yellow copy image is formed and fixed on the paper on which the above black image has been formed, using the chart with black horizontal stripes of 1 cIIL width as the original image. did. The coloration of the portion where the yellow line on the obtained copy overlapped with the first black image and the portion where the yellow line did not overlap but was directly formed on the white paper were visually evaluated. In addition, we used this together to measure the hiding power H of each toner.

The test results are shown in Table 2.

Table 2 Sample shop VVI Coloration on white paper C) 0 Coloration on black image ○ ×HO, 440,
69 As shown in the table, when a toner with an opacity of 0.6 or less was used, a clear color suitable for functional oak was obtained even on a black image.

Agent Yoshimi Kuwahara

Claims (1)

[Claims] (1) carrying an image of a first color (-1, or at least partially on an image support colored in a first color, on said image cover or colored part; In a multicolor image forming method in which an image of a second color is formed by electrostatic photography using 711, an electrostatic latent image is formed using a toner having the second color and having an opacity of 0.6 or less. forming an image of the second color obtained by developing the image on an image support having the image of the first color, or at least a part of which is colored in the first color; A multicolor image forming method characterized by fixation.