JPH0784092B2 - Flash fixing method Pre-print paper for non-impact printer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved pre-printed paper for a flash fixing type non-impact printer. More specifically, the present invention relates to a print paper for a non-impact printer using a flash fixing method, which has been previously printed with a black ink, and which does not substantially absorb near infrared light as the black ink. The present invention relates to a preprinted paper which is not affected by thermal irradiation due to flash irradiation and is remarkably improved in printer suitability.

2. Description of the Related Art Conventionally, in an electrophotographic non-impact printer (NIP), an image developed with toner on a photosensitive drum or photosensitive belt is transferred onto print paper, and the transferred toner image is transferred. A method of fusing by heat and fixing to the print paper is used. As a heating method for fixing the toner, a heat roll method in which a heat roll is directly pressed against the toner transfer surface to perform heat transfer heating, and a xenon / flash light including near infrared light is flash-irradiated to the toner transfer surface. The absorption of the near-infrared light can be roughly classified into a flash method of directly heating the toner.

In the former hot roll method, the heat resistance of the paper and the preprinted print paper are used because the print paper comes into direct contact with the transferred toner and the hot roll heated to a temperature of about 200 ° C. Ink is required to have heat resistance. Papers and ink materials satisfying such requirements have been developed so far, and printing papers having sufficient printer suitability are currently being supplied.

On the other hand, in the flash method, there is a feature that the toner or the like that absorbs the near-infrared portion of the flash light is selectively heated, and because the majority of the paper and ink that make up the printing paper do not absorb the near-infrared portion, Up until now, no special consideration has been given to print paper. By the way, in recent years, with the rapid increase in non-impact printers of the flash system and the diversification of print paper, there are many cases where print paper preprinted with black ink is used. However, in the preprinted paper, heating due to flash irradiation of black ink causes a decrease in ink adhesive force and distortion (curl, twist) due to heat of the paper, resulting in deterioration of the printer properness. It has been desired to develop a printing paper preprinted with a black ink having excellent suitability.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In response to such a demand, the present invention is hardly affected by thermal irradiation due to flash irradiation, and is a flash fixing method non-impact preprinted with a black ink having excellent printer suitability. -It was made for the purpose of providing print paper for printers.

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors first examined the effect of flash irradiation on the preprinted paper in the flash fixing type non-impact printer. That is, when the emission spectrum of the xenon flash light used in the flash fixing device is examined,
As shown in Fig. 1, a peak is seen near the wavelength of 850 to 1000 nm, and an emission wavelength region is also visible in the visible and near infrared regions. I found that I was involved in wearing.

On the other hand, as black ink, printing with high hiding power and high density is required. Therefore, except for a very small amount of special ink such as iron black, the one using carbon black as the main pigment is used. This carbon black is also blended as a black pigment in gray and dark brown inks, but there is a significant difference in the behavior to near infrared light between the ink containing this carbon black and the ink not containing it. I found out there was.

That is, FIG. 1 is a near-infrared reflection spectrum diagram measured by spreading black ink containing carbon black (A) and black ink not containing carbon black (B) on fine paper, respectively. It was confirmed that both show the same absorption in the wavelength region of 800 nm or less, but only the former is absorbed and the latter is hardly absorbed in the near infrared region of 800 nm or more. Then, when a black ink containing carbon black and a black ink not containing it were spread on fine paper and flash irradiation was tried, no change was observed in the spread on the ink containing no carbon black. However, in the case of ink-colored products containing carbon black, the temperature rise of the color-developed products and the distortion of the paper (curl, twist, etc.) are detected. It was found that the adhesive strength of the ink film decreased depending on the type of ink. On the other hand, the toner absorbs near-infrared light as in the case of carbon black, but has a small area, and the latent heat during fusion suppresses the temperature rise. Is estimated to be low.

Based on these findings, the present inventors pre-printed with a black ink that does not contain carbon black and substantially does not absorb near-infrared light, so that there is almost no thermal influence due to flash irradiation. Found that pre-print paper for flash-fixing non-impact printers with excellent printer suitability can be obtained,
The present invention has been completed.

That is, the present invention is a flash fixing type non-impact printer printing paper preprinted with a black ink, wherein the black ink is an ink that does not substantially absorb near infrared light. It provides pre-printed paper for fixing type non-impact printers.

The paper material used for the preprinted paper of the present invention is not particularly limited, and any of those conventionally used as print paper for flash fixing type non-impact printers can be used.

In the present invention, it is necessary to use a black ink that does not substantially absorb near-infrared light as the black ink used for preprinting the printing paper. The print paper preprinted with such ink is hardly affected by heat due to flash irradiation in the flash fixing type non-impact printer, and thermal denaturation such as distortion and burning does not occur. It excels in printer suitability because it does not reduce the adhesive strength of the ink film.

The black ink that does not substantially absorb near-infrared light, for example, carbon black free ink, that is, does not contain carbon black at all, or even if it contains the amount absorbed in the near-infrared region of wavelength 800nm or more. A small amount of black ink that does not show As such a black ink that does not substantially absorb near infrared light, a black ink prepared by mixing three primary colors of a red pigment, a blue pigment, and a yellow pigment or a black pigment other than carbon black. There is ink. Examples of the three primary color inks include cyan ink that absorbs red light when white light is applied to a color material, magenta ink that also absorbs green light, and yellow ink that absorbs blue-violet light. When the above colorants are mixed, the color light is reduced, so this is called subtractive color mixing, and it is possible to reproduce all colors in the natural world on the paper surface by the mixing ratio.

Such a black ink that does not substantially absorb near-infrared light is considered to be relatively difficult to obtain the hiding power and the density as compared with the black ink using the carbon black, and has not been put to practical use until now. It was However, according to the research conducted by the present inventors, it has been found that the hiding power and the density equivalent to those of the black ink using the carbon black can be obtained by only slightly increasing the amount of the black ink.

An embodiment of the present invention will now be described with reference to the accompanying drawings. FIG. 2 is a partial plan view showing an example of the preprinted paper of the present invention, which is printed on the paper 1 in advance in a printing column 2 , Title 3, and Item 4 are printed with black ink that does not substantially absorb near infrared light.

When non-impact printing is performed on this paper by the flash fixing method, the printed portion hardly absorbs near-infrared light like the paper surface, and therefore no undesired development such as curling or scorching appears.

The black ink is usually used by dispersing it in an ink vehicle appropriately selected depending on the desired type of printing paper, printing method, printing machine type, drying method, printing speed, and the like. In the present invention, the method of preprinting the black ink on the printing paper is not particularly limited, and any method such as letterpress printing, lithographic printing and gravure printing can be used.

EFFECTS OF THE INVENTION The pre-printing paper for flash fixing type non-impact printer of the present invention is not a black ink containing a conventional carbon black that absorbs near infrared light, but a carbon black that does not substantially absorb near infrared light. It is pre-printed with free black ink and is hardly affected by the thermal effect of flash irradiation, and does not cause distortion or charring. Moreover, even if a UV ink vehicle is used, it does not cause a decrease in the adhesive strength of the film, and is excellent in printer suitability.

As described above, the preprinted paper of the present invention does not need to consider the heat generated by the flash irradiation, and thus has a high degree of freedom in designing the paper, and can also support solid black printing, and meet the needs of customers. You can supply what you see.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Commercially available oil-based process ink (oxidized polymer), three colors of cyan, yellow, and magenta were mixed in a weight ratio of 1: 1: 1, and this was further kneaded and toned to visually produce a commercially available oil-based black ink. The color tone was the same as that of (oxidative polymerization type using carbon black).

To a density of 0.80 ± 0.05 on high quality paper (45kg continuous weight),
The kneading toned black ink and a commercially available oil-based black ink (manufactured by Toyo Ink Co., Ltd.) were each subjected to color development, and the reflection spectra of both ink color development products were measured. The results are shown in FIG.
Among these, A is a commercially available oil-based black ink, B is a kneading-toning black ink, and C is the spectrum of the paper itself. As can be seen from this figure, the commercially available oil-based black ink shows flat absorption in the near infrared region, but the kneading-toned ink shows almost no absorption in the long wavelength region of 800 nm or more.

Next, when the above-mentioned developed product was subjected to normal flash irradiation with a flash fixing device in a flash fixing type non-impact printer, a remarkable curl was generated on the paper with the commercially available oil-based black ink, but a kneading-colored black ink Then there was no change.

Example 2 The pigment composition corresponding to Example 1 was dispersed at a high concentration in an offset ink vehicle to prepare a carbon black-free ink having a practical hiding power and concentration.

Next, using this ink and a general black ink for comparison, preprint paper for printer test was prepared by offset printing, and a print test was conducted by a flash fixing type non-impact printer. As a result, preprinted paper using general black ink was curled due to flash irradiation and paper distortion occurred, and it became impossible to fold it with a stacker, but with the prepared carbon black free black ink there was no problem. It never happened. The reflection spectrum of each ink is the third
It was identical to that shown in the figure.

Example 3 The pigment composition corresponding to Example 1 was dispersed in a UV ink vehicle for offset, and the same test as in Example 2 was conducted.

As a result, the preprinted paper using the general UV black ink that absorbs near-infrared light could not be folded by the stacker as in Example 2, and the adhesive force of the ink film was lowered, and the eraser erased. Then, the concentration easily decreased. On the other hand, the preprinted paper using the UV carbon black-free black ink showed no change and showed good printer suitability.

[Brief description of drawings]

FIG. 1 is a near-infrared reflection spectrum of a black ink containing carbon black and a black ink not containing carbon black. FIG. 2 is a partial plan view showing an example of the paper of the present invention. It is a reflection spectrum figure of the paper obtained in the example.

Claims (2)

[Claims] 1. A flash fixing method non-impact printer print paper preprinted with black ink, characterized in that an ink that does not substantially absorb near infrared light is used as the black ink. Pre-printed paper for non-impact printers. 2. The preprint paper according to claim 1, wherein the black ink is a carbon black-free black ink obtained by subtractive mixing of general color pigments that does not substantially absorb near infrared light.