JPH0292642A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To improve fixing strength by providing a thermal head for thermally fixing ink composition after flying and adhering. CONSTITUTION:An ink jet head 16 has a plurality of nozzles capable of controlling injection of ink droplets independently of the head 16, swept in the axial direction of a platen, and ink droplets are selectively discharged from the nozzles to form an ink image on a recording sheet 10. Thermal heads 18a, 18b having a plurality of heaters capable of controlling dot heating independently follow the head 16, and scanned axially of the platen. In case of unidirectional printing, only the head 18a is heated. In case of bidirectional printing, the head 18a is heated at the time of rightward printing, while the head 18b is heated at the time of leftward printing, and an ink image formed by the head is selectively heated and fixed. Thus, the dots are blurred flatly, the dots are partly resolidified in a state of penetration into fiber near the surface of a recording sheet. Accordingly, fixing strength is satisfactory, scuffing resistance is provided, and high adhesive properties, high printing quality can be obtained.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an inkjet recording device.

More specifically, the present invention relates to an inkjet recording device that ejects an ink composition at a temperature higher than room temperature.

1. Prior Art 1 Inkjet recording is excellent in quietness during recording and high-speed printing performance. BACKGROUND ART Liquid ink compositions based on water or the like have conventionally been used as ink compositions for inkjet recording. However, since ink is recorded by soaking into the paper, it has the disadvantage that when recording on paper where ink easily soaks, bleeding occurs, the periphery of the recorded dots becomes unclear, and the print quality deteriorates.

For this reason, as a means to obtain good print quality regardless of the paper quality, US Patent No. 4390369.4484948.465
Using a hot-melt ink composition based on a wax or the like that is solid at room temperature, as shown in Japanese Patent Application Laid-open No. 9383 and Japanese Patent Application Laid-open No. 58-108271, the solid ink is melted by heating at a high temperature and then blown onto the recording paper. A hot-melt inkjet recording device is known that forms recorded dots by cooling and solidifying the ink.

[Problems to be Solved by the Invention] However, although conventional hot-melt inkjet recording devices can obtain good print quality regardless of paper quality, ink droplets swell up on the recording paper surface as shown in Figure 3. Because it solidifies in a state where it is
They have problems such as peeling off due to external friction, heat, pressure, etc., sticking to stacked objects, and causing printing to bleed. As a method to solve this problem, methods have been tried to fix the ink composition after flying and adhering using a roll heater, a light source, etc., but all of these methods consume a large amount of power and also require heat to be applied during the device operation. This poses a problem in that the device itself is complicated and cannot be miniaturized. .

The present invention is intended to solve these problems, and its purpose is to provide an inkjet recording device that has good fixing strength and can provide high print quality regardless of the quality of the recording paper.

1. Means for Solving Problems] The inkjet recording device of the present invention is an inkjet recording device that flies an ink composition at a temperature higher than room temperature, and a thermal fixing method that heats and fixes the ink composition after flying and adhering. It is characterized by having a head.

As the thermal head of the present invention, any conventionally known thermal head can be used as is, as long as it has the same dot pitch as an inkjet head. According to the present invention, since a thermal head is used, power consumption is low, and in addition, only printed dots can be selectively heated and fixed, thereby avoiding wasteful power consumption.

The temperature at which the thermal head generates heat depends on the physical properties of the ink and the printing speed, but it is suitable to be in the vicinity of the melting point, specifically in the range of 10°C lower than the melting point to 30°C higher than the melting point, and 20°C higher than the melting point. A further range of temperatures from 20°C below the melting point remains.

If the temperature is too high than the melting point, smearing or printed characters will occur, and if it is lower than the melting point, the fixing will be insufficient and adhesion and abrasion resistance will not be obtained.

When ink ejected by an inkjet head and cooled and solidified is heated and fixed by a thermal head, there is a problem that the ink comes into direct contact with the thermal head, staining the thermal head. This problem can be solved by heat fixing using an ink-repellent film such as naphthalate or polytetrafluoroethylene.

[Function] In the inkjet recording device of the present invention, the ejected ink collides with the recording paper, cools and solidifies, and is then heated and fixed by the thermal head, thereby flattening the dots as shown in FIG. Since a part of the adhesive penetrates into the fibers near the surface of the recording paper and is re-assimilated, it has good fixing strength and one-shot resistance, and it is possible to obtain high adhesion and high print quality.

[Example] Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto.

FIG. 1 is a perspective view of an inkjet recording apparatus showing an embodiment of the present invention. In this figure, recording paper 10 is wound around platen 11 and is pressed by feed rollers 12, 13. An inkjet head 16 and thermal heads 18a and 18b are mounted on both sides of the inkjet head 16 on a carriage 15 that is guided by guide shafts 14 and 17 and movable in a direction parallel to the platen axis. The inkjet head 16 has a plurality of nozzles that can independently control the ejection of ink droplets, and is scanned in the platen axis direction, selectively ejecting ink droplets from the nozzles to form an ink image on the recording paper 10. A thermal head 18a is provided on both sides of the inkjet head 16 and has a plurality of heating elements that can also independently control dot heating.
18b follows the inkjet head 16 and scans in the platen axis direction, and in the case of unidirectional printing, the thermal head 18
Only a generates heat, and in the case of bidirectional printing, the thermal head 18a is used when printing in the right direction, and the thermal head 18 is used when printing in the left direction.
b generates heat and selectively heats and fixes the ink image formed by the inkjet head. The recording paper 10 is conveyed in a sub-scanning direction perpendicular to the scanning direction by rotation of a platen 11 and feed rollers 12 and 13, and printing is performed on the surface of the recording paper.

The temperature of the thermal head when it generates heat is controlled to be close to the melting point of the ink, as described above.

After performing bit image printing, character printing, etc. on general high-quality paper, bond paper, PPC paper, etc. using the ink composition shown in Table 1 according to the inkjet recording method of the present invention,
When A1-A3 were evaluated, good results were obtained.

(A1) Printing abrasion resistance: After printing on various types of recording paper, the printed surface is rubbed with a sand eraser under a load of 500 g/cm', and the presence or absence of stains is evaluated by the number of times of rubbing. No occurrence after 30 reciprocations or more 09. Suitable (O)・20
Occurred after ~30 reciprocating frictions 60. Appropriate (0) - Occurred after 10 reciprocating frictions 61. When classified and evaluated by unsuitability (X), all of them were rated "suitable" or higher, although there were some differences depending on the paper quality.

(A2) Printed matter blocking property: After placing blank recording paper on top of the recording paper at a high temperature of 60°C and leaving it under pressure from above for 24 hours, the ink smeared on the recording paper surface and the overlapped recordings were observed. Inspect the presence or absence of ink transfer to the paper. ・Ink smudge, no ink transfer 09. Fair (0) - Ink bleeding and ink transfer 18. As a result of classification and evaluation based on unsuitability (x), no ink bleeding occurred and no ink transfer was observed.

(A3) Ink dot flatness: Measure the height of the ink dot on the recording paper and evaluate its adhesion to the recording paper.Dot height is 10 microns [1/1/2 or less, and adhesion is sufficient.
... Suitable (o) - Dot height is 10 to 20 microns and has sufficient adhesion.
... Suitable (0) - Dot height is higher than 20 microns and adhesion is insufficient ... Unsuitable (x)
When categorized and evaluated by

As a comparative example, similar printing was carried out on various types of recording paper using a conventional hot-melt inkjet recording device using ink having the composition shown in Table 1.
As a result of the evaluation, the results shown in Table 2 were obtained.

(Composition) Carnauba wax 20. Owt% Lauron 65.2wt% Palmitic Acid Amide 9.8wt% Polyseed) (1-sense fluorocarbon GHH) (Hodogaya Chemical Industry) 5.0
wt% (physical properties) Melting point 67.4 °C Viscosity (10
0°(:) 5.3 mPa-5
1st front bond paper a:! Standard paper b: Run h Starboard PPC paper a: Paper (l book-4024 PPC paper b: Seven-print paper B) It goes without saying that the effects of the present invention can be achieved with any mechanism as long as the ink image ejected and printed is fixed by heating using a thermal head.

For example, the effects of the present invention can be achieved even in an apparatus in which 16 in FIG. 1 is replaced with a thermal head and 18 is replaced with an inkjet head.

1 Effects of the Invention 1 As described above, in an inkjet recording device that flies an ink composition at a temperature higher than room temperature, recording can be achieved by having a thermal head that heats and fixes the ink composition after it flies and adheres. It has the effect of providing good printing with high fixing strength, good abrasion resistance, and good dot reproducibility, regardless of the paper quality.

In addition, since the ink dots are flat, when printing in color, the color mixture in the overlapping areas of different color ink dots is uniform and clear, and even when printing in color on OHP sheets, there is no unevenness in the projected image, which is a special effect. It also has

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of an inkjet recording apparatus of the present invention. FIG. 2 is a cross-sectional view of an ink image printed by the inkjet recording apparatus of the present invention. FIG. 3 is a cross-sectional view of an ink image printed by a conventional inkjet recording device. 10 δ Self-recording paper 16 Inkjet head 18 Thermal head 20 Ink and above Applicant Seiko Epson Co., Ltd. Representative Patent Attorney Mitsuki Sanbe and 1 other person Figure 1

Claims (1)

[Claims] An inkjet recording device that jets an ink composition at a temperature higher than room temperature, the inkjet recording device comprising a thermal head that heats and fixes the jetted and adhered ink composition.