JPH04261477A - Recording medium which is solid at ordinary temperature and method for recording - Google Patents

Abstract

PURPOSE:To obtain a recording medium which is a solid at ordinary temperature, containing a carbamic acid ester and a colorant, excellent in fixing properties of recorded images and capable of providing the high-quality recorded images without bleeding even on plain paper. CONSTITUTION:A recording medium which is a solid at ordinary temperature, containing (A) a carbamic acid ester such as methyl carbamate or ethyl carbamate and (B) a colorant such as an oil-soluble dye or a direct dye and capable of effectively converting thermal energy into discharge energy without changing physical properties and causing clogging of nozzles. The aforementioned recording medium is melted by heating and thermal energy according to a recorded signal is further applied to discharge the above-mentioned recording medium from a discharge orifice. Thereby, recording is readily carried out.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a room temperature solid recording medium and a recording method, and more particularly to a room temperature solid recording medium and a recording method used in an inkjet recording method.

0002

[Prior Art] The inkjet recording method uses a recording medium (
Recording is performed by causing small droplets of ink to fly and adhere to a recording material such as paper. In particular, the applicant
1-59911, Japanese Patent Publication No. 61-59912, and Japanese Patent Publication No. 61-59914, by using an electrothermal converter as the ejection energy supply means and applying thermal energy to the ink to generate bubbles. According to the method of ejecting droplets, a high-density multi-orifice recording head can be easily realized, and high-resolution, high-quality images can be recorded at high speed.

On the other hand, the ink used in the inkjet recording method quickly dries and fixes on the recording material, does not dry easily in the nozzle, and is less likely to cause nozzle clogging.
These contradictory characteristics are required.

[0004] In response to this demand, conventional inks generally have water as their main component, and generally contain a water-soluble high boiling point solvent such as glycol for the purpose of preventing drying and clogging. When recording on plain paper using ink, the ink does not dry and fix quickly, and when you touch the printed characters, the ink sticks to your hand or the characters rub, resulting in poor print quality. was there.

[0005] Furthermore, since the permeability of ink varies greatly depending on the type of recording paper, when using conventional inks containing water as a main component, there is a problem that only specific recording papers can be used. Particularly in recent years, there has been a demand for good recording even on so-called plain paper, such as copy paper, report paper, notebook paper, and stationery paper, which are often used in offices.

On the other hand, the present applicant disclosed a recording medium that is solid at room temperature and a recording method using the same in Japanese Patent Laid-Open No. 55-54368. According to this invention, there is no nozzle clogging, the printing fixation speed is fast, and it is possible to perform robust and high-quality recording on plain paper.

[0007]

[Problem to be solved by the invention] However,
No. 54368 discloses various inkjet recording methods (
For example, recording media and recording methods used in devices such as those that eject droplets using a piezo vibrator, those that eject droplets using electrostatic suction, and those that eject droplets using thermal energy, etc.) are not necessarily based on thermal energy. This was not the best method for recording by ejecting droplets, and there was still room for improvement. In other words, a recording medium used in a recording method that ejects droplets by applying thermal energy to ink to generate bubbles has to meet the various characteristics required of a recording medium for inkjet recording. It also needs to be excellent in its ability to convert into

Conventional inks that are solid at room temperature and used in a recording method in which droplets are ejected using thermal energy are disclosed in Japanese Patent Application Laid-open Nos. 1-236287 and 1-263170.
No. 1 and JP-A-1-263171, xylenol, diacetamide, 2,2-dimethyl-1-
An ink containing propanol as a main component is disclosed.

However, with these conventional solid inks, when left in a heated molten state without recording,
The physical properties of the ink changed and nozzle clogging was likely to occur.

The present invention has been made in view of the above-mentioned circumstances, and is capable of providing excellent fixation properties of recorded images, high-quality recorded images without bleeding even on plain paper, and moreover, it is possible to obtain a high-quality recorded image without bleeding even on plain paper. The purpose of the present invention is to provide a room-temperature solid recording medium and a recording method that can be effectively converted into a solid state at room temperature.

[0011]

[Means for Solving the Problems] The room-temperature solid recording medium of the present invention is a recording medium used in a recording method in which recording is performed by ejecting the recording medium from an ejection orifice by applying thermal energy. It is characterized by containing at least an ester and a colorant.

Furthermore, the recording method of the present invention uses a recording medium that is solid at room temperature and contains at least a carbamate ester and a colorant, and the recording medium is heated and melted;
Furthermore, the recording medium is ejected from an ejection orifice by applying thermal energy according to a print signal to perform printing.

[0013] The recording medium of the present invention can be stored at room temperature (5°C to 35°C).
) is fixed. Therefore, when the recording medium of the present invention is used in a recording method in which droplets are ejected using thermal energy, the recording medium is heated and melted, and the molten recording medium is heated in accordance with the recording signal, as will be described in detail later. Recording is performed by ejecting from the ejection orifice by applying energy.

When thermal energy corresponding to a recording signal is applied to the recording medium of the present invention in a molten state, bubbles are generated within the recording medium, and the bubble generation generates ejection energy that causes the recording medium to be ejected from the ejection orifice. occurs. The ejection energy varies depending on the state of bubble generation. The state of bubble generation depends on the physical properties of the recording medium.

The recording medium of the present invention efficiently converts thermal energy corresponding to a recording signal into ejection energy in a molten state, that is, it has excellent ejection characteristics.

The ejection characteristics of the recording medium will be explained in detail below.

The present inventor investigated the ejection characteristics of a room-temperature solid recording medium using the apparatus shown in FIG. The recording apparatus shown in FIG. 1 is designed to allow observation of the foaming state in the recording medium. Using this apparatus, the correlation between the foaming state and the ejection state (quality of ejection) of the recording medium was investigated.

The recording head 6 is provided with walls 68 arranged in parallel on a substrate 61 and a wall 69 forming a liquid chamber 65, as shown in FIGS. 2(a) and 2(b). Furthermore, the wall 68
, 69, a transparent top plate 64 is arranged. Figure 2 (a
), in order to make it easier to see the inside of the recording head 6, the top plate 6 is
4 is shown separated from walls 68, 69. An ink supply port 67 is formed in the top plate 64, and a molten recording medium flows into the liquid chamber 65 from the ink supply port 67. wall 68 and wall 68
Between the walls 68 and 69 are nozzles 62 through which the molten recording medium passes, and the substrate 61 in the middle of each nozzle 62
A heater 63 is provided above to apply thermal energy to the recording medium according to the recording signal. Bubbles are generated in the recording medium due to thermal energy from the heater 63, and the recording medium is discharged from the discharge orifice 62a of the nozzle 62.

A microscope 1 is placed above the nozzle 62 so that the inside of the nozzle 62 can be observed through a top plate 64, as shown in FIG. Strobe 2 for microscope 1
is attached so that the bubbling state of the recording medium can be observed only when the strobe 2 emits light. A strobe drive circuit 3 and a delay circuit 4 cause the strobe 2 to emit light after an arbitrarily set delay time elapses after the heater 63 starts applying heat.

The recording head 6 is provided with a heating means 7, which heats the recording head 6 to a temperature of 10° C. to 2° C. above the melting point of the recording medium.
The recording medium is kept in a molten state by heating to a temperature higher than 0°C. 5
8 is a head drive circuit, and 8 is an external power supply. The dimensions of the nozzle 62 are 25 μm in height, 40 μm in width, and 500 μm in length. The heater 63 has a width of 20 μm and a length of 120 μm.
The distance from the end of the heater 63 on the orifice 62a side to the orifice 62a is 120 μm. The number of nozzles 62 provided in the recording head 6 is 256 nozzles, and the nozzle density is 400 nozzles per inch.

In this way, by filling the liquid chamber 65 with the molten recording medium and energizing the heater 63 in pulses,
Bubbles generated on the heater 63 were observed while changing the delay time of strobe light emission. Note that the recording medium used in the study of ejection characteristics did not contain a colorant, or even if it contained it, it contained only a very small amount. This is because when a large amount of colorant is contained, bubbles become difficult to see. Further, the conditions for energizing the heater 63 are a pulse width of 7 μS, an applied voltage of 25 to 30 V,
The driving frequency was set to 100Hz.

As a result of examining the ejection characteristics, if the ejection of the recording medium is good, as shown in FIG. It was found that a single bubble covered the above (hereinafter referred to as "single boiling"). As shown in Fig. 4, the generated bubbles 33 are transferred to the heater 6.
3, or when multiple small bubbles 34 cover the heater 63 as shown in FIG. 5, and none of the bubbles covers more than 1/2 of the area of the heater 63,
Sufficient ejection energy was not generated, and the recording medium was not ejected from the ejection orifice.

As a result of examining single boiling by changing the main component of the recording medium, it was found that single boiling occurs when the recording medium contains a carbamate ester as the main component. It was also found that the recording medium containing carbamate ester has a reduced amount of evaporation from the recording head, and the physical properties of the recording medium do not change and the nozzles do not become clogged.

As the carbamate ester contained in the recording medium of the present invention, for example, methyl carbamate, ethyl carbamate, propyl carbamate, butyl carbamate, etc. are preferably used.

Further, according to the recording medium of the present invention, the recorded image has good fixing properties, and even when recorded on plain paper, a high-quality recorded image without bleeding can be obtained.

As the coloring agent contained in the recording medium of the present invention, various dyes and pigments such as conventionally known direct dyes, acid dyes, basic dyes, disperse dyes, vat dyes, sulfur dyes, and oil-soluble dyes are effective. It is. Particularly preferably used dyes include oil-soluble dyes listed in the following color index.

C. I. Solvent Yellow
1, 2, 3, 4, 6, 7, 8, 10, 12, 13,
14, 16, 18, 19, 21, 25, 25: 1, 28
,29,30,32,33,34,36,37,38,
40, 42, 43, 44, 47, 48, 55, 56, 5
8, 60, 62, 64, 65, etc.C. I. Solvent Orange 1, 2,
3, 4, 4: 1, 5, 6, 7, 11, 16, 17, 19
,20,23,25,31,32,37,37:1,3
8, 40, 40: 1, 45, 54, 56, 59, 60,
62, 63, 67, 68, 71, 72, 73, 74, 7
5th class C. I. Solvent Red 1, 2, 3, 4
,7,8,13,14,17,18,19,23,24
,25,26,27,29,30,33,35,37,
41, 42, 43, 45, 46, 47, 48, 49, 4
9:1,52,68,69,72,73,74,80,
81, etc.C. I. Solvent Violet 2, 3,
8,9,10,11,13,14,21,21:1,2
4, 31, 32, 33, 34, 36, 37, 38, 45
, 46, 47 etc.C. I. Solvent Blue 2, 4, 5,
7, 10, 11, 12, 22, 25, 26, 35, 36
,37,38,43,44,45,48,49,50,
51, 63, 64, 66, 67, 68, 70 etc.C. I.
Solvent Green 1, 3, 4, 5, 7
,8,9,20,26,28,29,30,32,33
etc.C. I. Solvent Brown 1,1:1
,2,3,4,5,6,12,19,20,22,25
,28,29,31,37,38,42,43,44,
48, 49, 52, 53, 58 etc.C. I. Solvent Black 3, 5, 6
,7,8,13,22,22:1,23,26,27,
28, 29, 33, 34, 35, 39, 40, 41, 4
2, 43, 45, 46, 47, 48, 49, 50, etc. In the recording medium of the present invention, the content of carbamate ester is 50 to 99% by weight based on the recording medium, and more preferably 6
0 to 95% by weight is preferred.

[0028] The content of the colorant is 1 to 1 with respect to the recording medium.
20% by weight, more preferably 3-15% by weight.

The recording medium of the present invention may optionally contain a binder that is solid at room temperature, such as beeswax, lanolin, carnauba wax, candelilla wax, montan wax, ceresin wax, paraffin wax, microcrystalline wax, oxidized wax, and ester. Waxes such as wax, low molecular weight polyethylene wax, polyamide resin, polyurethane resin, polyester resin, epoxy resin, polyolefin resin, polyacrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, etc. It may contain resins. These binders improve the fixability of recorded images. The content of the binder is preferably 0 to 20% by weight based on the recording medium, and the melting point is preferably 40°C to 150°C.

The recording medium of the present invention may also contain organic solvents that are liquid at room temperature, such as 1-hexanol and 1-hexanol, if necessary.
-Alcohols such as heptanol and 1-octanol,
It may contain alkylene glycols such as ethylene glycol, propylene glycol, and triethylene glycol, as well as other ketones, keto alcohols, amides, ethers, and the like. These organic solvents cause bubbles generated in the recording medium to grow larger. The content of the organic solvent is preferably 0 to 10% by weight based on the recording medium, and the boiling point is preferably 150° C. or higher.

In addition to the above, the recording medium of the present invention may contain various additives such as antioxidants, dispersants, and rust preventives.

The recording medium of the present invention can be obtained by mixing the above materials under heating.

Next, a recording method using the recording medium of the present invention will be explained. The apparatus shown in FIG. 6 is an apparatus for carrying out the recording method of the present invention, and a recording medium contained in a tank 41 is supplied to the recording head 6 through a supply path 42. The recording head 6 is similar to that described in FIGS. 2(a) and 2(b). Heating means 40 and 7 are provided in the tank 41, the supply path 42, and the recording head 6, and the recording medium in the apparatus is kept in a liquid state by the heat of the heating means 40 and 7 when the recording apparatus is driven. The heating means 40 and 7 are set to a predetermined temperature by the temperature control means 46. Recording head 6
A recording signal is sent from the drive circuit 45, and the heater 63 of the recording head 6 generates heat in accordance with the recording signal.

In this way, the recording medium in the tank 41 is supplied to the recording head 6 while being kept in a liquid state, and is ejected as small droplets from the ejection orifice of the recording head in accordance with the recording signal onto the recording paper 44. Form a recorded image.

[0035]

[Examples] The present invention will now be described in more detail with reference to Examples.

(Example 1) 95 parts by weight of methyl carbamate was melted by heating, and C.I. I. Solvent black 3
(C.I.Solvent Black 3) 5
After adding parts by weight and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 2) 70 parts by weight of methyl carbamate and 27 parts by weight of paraffin wax (150F, manufactured by Nippon Seiro Co., Ltd.) were heated and melted and mixed, and then C.I. I. Solvent Black 29 (C.I.Solvent Bl
After adding 3 parts by weight of ack29) and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 3) 76 parts by weight of methyl carbamate and microcrystalline wax (Hi-Mic10
20 parts by weight of C.80 (manufactured by Nippon Seiro Co., Ltd.) were heated and melted and mixed. I. Solvent Black 3 (C.I.
After adding 4 parts by weight of Solvent Black 3) and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 4) 81 parts by weight of methyl carbamate and 13 parts by weight of Candelilla wax (Candelilla special edition, manufactured by Noda Wax Co., Ltd.) were heated and melted and mixed, and then C.I. I. Solvent Black 3 (C.I.Sol
After adding 6 parts by weight of vent Black 3) and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 5) 84 parts by weight of methyl carbamate was melted by heating, and 10 parts by weight of ethyl alcohol and C.I. I. Solvent Black 29 (C.I.S.
Add 6 parts by weight of Olvent Black29) and
After stirring for an hour, the mixture of ingredients was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 6) 81 parts by weight of ethyl carbamate and 13 parts by weight of myristic acid were heated and melted, and C
．． I. Solvent Black 3 (C.I.Solve
After adding 6 parts by weight of nt Black3) and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 7) 84 parts by weight of ethyl carbamate was melted by heating, 10 parts by weight of ethyl alcohol and C.I. I. Solvent Black 29 (C.I.Sol
After adding 6 parts by weight of Vent Black 29) and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 8) n-butyl carbamate 90
parts by weight and 5 parts by weight of stearic acid are heated and melted and mixed,
Furthermore, C. I. Solvent Black 3 (C.I.Solv
After adding 5 parts by weight of ent Black 3) and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Example 9) 80 parts by weight of propyl carbamate and 15 parts by weight of palmitic acid were heated and melted and mixed,
Furthermore, C. I. Solvent Black 3 (C.I.Solv
After adding 5 parts by weight of ENT Black3) and stirring for 3 hours, the mixture of the components was filtered. Thereafter, the filtrate was cooled to room temperature to obtain a recording medium of the present invention.

(Comparative Example 1) Recording was carried out in the same manner as in Example 1 except that 95 parts by weight of methyl carbamate was replaced with 95 parts by weight of ester wax (Hoechst Wax E, manufactured by Hoechst Co., Ltd.) using the recording medium of Example 1. Got the medium.

(Comparative Example 2) A recording medium was prepared in the same manner as in Example 2, except that 70 parts by weight of methyl carbamate was replaced with 70 parts by weight of ester wax (Hoechst Wax E, manufactured by Hoechst). I got it.

(Comparative Example 3) In the recording medium of Example 3, 76 parts by weight of methyl carbamate was added to 76 parts by weight of microcrystalline wax (Hi-Mic1080, manufactured by Nippon Seiro Co., Ltd.).
A recording medium was obtained in the same manner as in Example 3 except for changing the parts by weight.

(Comparative Example 4) A recording medium was obtained in the same manner as in Example 6 except that 81 parts by weight of ethyl carbamate was replaced with 81 parts by weight of myristic acid.

(Comparative Example 5) A recording medium was obtained in the same manner as in Example 7 except that 84 parts by weight of ethyl carbamate was replaced with 84 parts by weight of myristic acid.

(Comparative Example 6) A recording medium was obtained in the same manner as in Example 8 except that 90 parts by weight of n-butyl carbamate was replaced with 90 parts by weight of stearic acid.

The recording media obtained in Examples 1 to 9 and Comparative Examples 1 to 6 above were ejected from the recording head 6 of the recording apparatus shown in FIG. 6, and recorded on commercially available copy paper. As the recording head, a recording head similar to that described in FIG. 1 was used. The recording head has a heater voltage of 28.5V.
, pulse width 7 μsec. , and was driven at a driving frequency of 100 Hz.

[0052] Furthermore, the temperature control means 46 controls the tank 41,
The supply path 42 and recording head 6 were heated to 90°C. Figure 6
A microscope 1 shown in FIG. 1 was installed in the recording apparatus shown in FIG. 1, and the discharge state of the recording medium was observed. In this way, the ejection state of the recording medium, the fixation of the recorded image, and the bleeding of the recorded image were evaluated.

To evaluate the ejection state of the recording medium, eject the recording medium continuously, and check the ejection state of the recording medium after one hour (
(presence of clogging, change in discharge speed, etc.) Furthermore, after the ejection of the recording medium was completed, the temperature control means 46 was driven and the ejection was left for 24 hours, and then ejection was performed again and the ejection state was evaluated (presence or absence of clogging). The ejection state was evaluated by ejecting the recording medium from 24 consecutive nozzles.

To evaluate the fixing performance, image signals are applied to 16 heaters 63 in a checkerboard pattern for each pixel, the recording medium is ejected, the recording medium is recorded on copy paper, and 10 seconds later, the recorded image is transferred to filter paper (commercial product). A rubbing evaluation was performed using No. 5c (manufactured by Toyo Roshi Co., Ltd.).

For the evaluation of bleeding, the same recording pattern as in the evaluation of fixability is recorded on copy paper, and the presence or absence of bleeding is observed for each dot making up this recorded pattern using a microscope, and the rate of occurrence of bleeding is determined. evaluated.

The evaluation results for Examples 1 to 9 are shown below.

Regarding the discharge status after continuous discharge for 1 hour,
No clogging occurred in any of the Examples, and no change in discharge speed was observed. Regarding the discharge state after being left for 24 hours, no clogging occurred in any of the Examples.

Fixing was completed within 10 seconds in all Examples, and no stains were observed even when the recorded image was rubbed with filter paper.

Regarding bleeding, no dots with bleeding were observed in any of the examples.

On the other hand, in Comparative Examples 1 to 6, the recording medium could not be ejected and a recorded image could not be formed.

[0061]

As explained above, in the present invention, since the recording medium contains at least a carbamate ester, single boiling occurs on the heater of the recording head, and the recording medium is favorably discharged from the discharge orifice. In addition, the amount of the recording medium that evaporates from the recording head is small, and the physical properties of the recording medium do not change or the nozzles become clogged. Furthermore, since the recording medium of the present invention is resistant to evaporation, its physical properties do not change even after long-term storage.

Furthermore, the recording medium of the present invention has excellent fixation properties of recorded images, and can provide high-quality recorded images without bleeding even on plain paper.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a recording device that allows observation of a foaming state of a recording medium.

FIG. 2 is a diagram of a recording head used in the recording apparatus of FIG. 1;

FIG. 3 is a plan view showing an example of a foamed state observed using the recording device of FIG. 1;

FIG. 4 is a plan view showing an example of a foamed state observed using the recording device of FIG. 1;

FIG. 5 is a plan view showing an example of a foamed state observed using the recording device of FIG. 1;

FIG. 6 is a schematic diagram showing an example of a recording device using the recording medium of the present invention.

[Explanation of symbols]

1　Microscope 2 Strobe 6 Recording head 7 Heating means 32, 33, 34 bubbles 41 Tank 42 Supply route 44 Recording paper 46 Temperature control means 62 Nozzle 62a Discharge orifice 63 Heater 67 Ink supply port

Claims (2)

[Claims] [Claim 1] By applying thermal energy,
A recording medium used in a recording method in which recording is performed by discharging the recording medium from a discharge orifice, which contains carbamate ester,
A recording medium that is solid at room temperature and contains at least a colorant. 2. Using a room-temperature solid recording medium containing at least a carbamate ester and a colorant, the recording medium is heated and melted, and thermal energy corresponding to a recording signal is applied to the discharge orifice. A recording method characterized by performing recording by ejecting a recording medium.