JPH03258871A - Ink and ink-jet recording method using thereof - Google Patents

Abstract

PURPOSE:To obtain ink used in an ink-jet recording method capable of recording to normal paper in high definition and high image quality suitable for a method utilizing thermal energy containing coloring matter, water and hydroxymethyl propanediol. CONSTITUTION:The aimed ink contains coloring matter, water and 2- hydroxymethyl-1,3-propanediol preferably in an amount of 0.1-30wt.%. In recording, liquid drop of said ink is formed by applying thermal energy corresponding to recording signals to the ink and said liquid drop is applied to a recording material to perform recording.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable not only to coated paper specially prepared for inkjet use, but also to other types of copy paper, report paper, pound paper, continuous slip paper, etc. Even for uncoated paper, so-called plain paper, commonly used in offices and homes,
The present invention relates to an ink that enables high-definition, high-quality recording and is suitable for systems that utilize thermal energy, and an inkjet recording method using the same.

[Conventional technology]

Conventionally, inkjet inks having a wide variety of compositions have been reported. In particular, in recent years, detailed research and development has been carried out from various aspects such as composition and physical properties in order to perform good recording on plain paper commonly used in offices such as copy paper, report paper, notebooks, and stationery. has been done.

Various methods have also been proposed for inkjet recording, including a method in which electrically charged droplets are continuously generated and a portion of the droplets are used for recording, and a method in which a signal is applied to a recording head having a piezoelectric element. , a method in which recording is performed by generating droplets of recording liquid in response to the signal, or a method in which thermal energy corresponding to the recording signal is applied to the recording liquid in the chamber of the recording head, and the energy is used to generate droplets to perform recording. There are methods etc.

In particular, the type described in Japanese Patent Application Laid-open No. 54-59936, which ejects ink by the ink bubbling phenomenon caused by thermal energy, has been attracting particular attention recently because it is easy to increase the integration and density of the nozzles. This is a method in which However, because it takes advantage of the phenomenon of foaming that other methods do not have, strict conditions are required for the ink used.

Preferred conditions for the ink used in this method are listed below. does not occur.

(2) Even if the printer is left without a cap during a recording pause, stable ejection can be obtained immediately after recording is resumed. That is, the ink near the ejection ports is less likely to dry and clogging does not occur.

(3) High-quality images without irregular shapes or irregular bleeding can be obtained, especially on plain paper.

(4) Faster fixation (print drying) than on plain paper;
Even if you rub the printed matter, it will not get dirty.

(5) Good storage stability and ink performance maintained over a long period of time.

(6) Excellent safety in terms of toxicity and flammability.

etc.

In response to these demands, conventional ink formulations are not limited to a single thermal energy ejection method, but generally include high-boiling point substances such as glycol in the ink for the purpose of preventing drying and clogging. When recording with such ink on plain paper with a high degree of size because it contains an organic solvent, it is difficult for the ink to penetrate into the inside of the paper and the drying of the recorded area is poor, so it is difficult to manually record the recorded matter. There were problems such as the ink getting on your hands when you touched it, and the letters getting rubbed and getting dirty.

Therefore, in order to improve the permeability of the ink into the inside of the paper, Japanese Patent Application Laid-Open No. 55-29546 proposes a method of adding a large amount of surfactant to the ink. In this case, depending on the paper, there may be a lot of bleeding, or when filling an inkjet head, depending on the structural conditions of the head, the ink may recede from the orifice surface and no ejection occurs, or conversely, the orifice may Problems such as the entire surface getting wet and ink not being ejected were observed.

Furthermore, JP-A-56-57862 proposes a method of making the pH of the ink strongly alkaline, but in this case it is dangerous if the ink is touched by hand, and it also For example, acid-free paper may bleed,
There are drawbacks such as poor drying properties.

In addition to the above, various improvements have been attempted so far, but even without the limitation of using only one type of thermal energy, all of the problems of bleeding, drying, and clogging can be satisfactorily solved. To date, no ink has been known that can do this, and in addition, it is important but extremely difficult to design an ink that has the ability to respond favorably to the phenomenon of foaming, which is unique to thermal energy systems. This is a serious issue.

[Problems to be Solved by the Invention] Therefore, the object of the present invention is to provide a non-coated material that has good foaming response to thermal energy and that is commonly used in offices such as copy paper, report paper, notebooks, and stationery. An object of the present invention is to provide an ink that solves the problem of ink bleeding and slow drying of recorded matter when recording on paper, so-called plain paper, and an inkjet recording method using the same.

Another object of the present invention is to provide an ink that is highly safe for use in offices and homes.

Furthermore, another object of the present invention is to provide an ink that is less likely to cause clogging due to noise in an inkjet recording head and has excellent reliability.

[Means and effects for solving the problems] The above objects are achieved by the present invention as described below.

That is, the present invention is characterized in that ink droplets are formed by applying thermal energy corresponding to a recording signal to the ink, and contain a pigment, water, and 2-hydroxymethyl-1,3-propanediol. This is an inkjet recording method in which recording is performed using such ink.

The inventors of the present invention have found that the invention is particularly suitable for recording in which ink is ejected by the ink bubbling phenomenon caused by thermal energy, improves ink bleeding, drying properties, and permeability on paper, and further prevents clogging in the nozzles of an inkjet recording head. As a result of intensive research into an ink composition that is highly reliable and resistant to bleeding, we found that an ink that contains water and 2-hydroxymethyl-1,3-propanediol as a liquid medium has a good balance in terms of bleeding and permeability. Furthermore, it was discovered that the anti-clogging properties are particularly good, leading to the present invention.

According to the knowledge of the present inventors, glycols such as polyethylene glycol, glycerin, etc. have been used as conventional ink clogging prevention agents, and glycerin in particular can prevent clogging by adding a relatively small amount. It is a particularly preferred anti-clogging agent because it can prevent ink from bleeding on the paper surface. However, since the ink has poor wettability with the sizing agent present in the paper, it has the disadvantage that, depending on the paper, the drying properties and permeability of the ink on the paper surface are extremely poor.

In contrast, 2-hydroxymethyl-1 used in the present invention
, 3-propanediol has the same clogging prevention effect as glycerin, and has a very good balance between ink bleeding and permeability. The reason for this is thought to be that the compound has a low vapor pressure and has three hydroxyl groups like glycerin, so it has excellent dissolution or dispersibility of dyes, and as a result, the clogging prevention effect is obtained. Furthermore, since it has more carbon atoms than glycerin, it has a hydrophilic part and a hydrophobic part in the molecule, so it has good wettability to the sizing agent, and it is thought that this results in a marked improvement in the permeability of the ink on the paper surface.

On the other hand, the responsiveness to foaming is particularly good when the content of the compound in the ink is 0.1 to 30% by weight and water is also contained in 50 to 95% by weight. This is considered to be because the physical properties of the ink mixed at the above ratio and the wettability to each member inside the nozzle are optimal for a recording method in which ink is ejected by a bubbling phenomenon of ink caused by thermal energy.

[Preferred embodiment]

Next, each component of the ink of the present invention will be explained.

2-Hydroxymethyl-1,3-propanediol used in the present invention and which mainly characterizes the present invention is added to the ink alone or in a mixed system. Although it varies depending on the situation, about 0.1 to 30% by weight, preferably 0.1 to 25% by weight,
More preferably, the proportion is 1 to 20% by weight.

When this content is less than 0.1% by weight, no clogging prevention effect is observed. Moreover, if this content exceeds 30% by weight, problems will arise in terms of permeability and bleeding.

The pigments constituting the ink of the present invention include direct dyes, acid dyes, food dyes, basic dyes, reactive dyes, disperse dyes,
architectural dyes, soluble architectural dyes, reactive disperse dyes, oil dyes,
Various pigments may be used, but water-soluble dyes are particularly preferred from the viewpoint of ink performance.

The content of these pigments is determined depending on the type of liquid medium components, the properties required of the ink, etc., but - numerically, it is about 0.2 to 20% by weight in the total amount of ink, preferably 0
．． The proportion is 5 to 10%, more preferably 1 to 5%.

Further, the proportion of water in the ink, which is an essential component of the present invention, is 50 to 95% by weight, preferably 55 to 95% by weight.
, more preferably 60 to 95% by weight. When the amount of water is less than 50% by weight, the amount of organic solvent is large;
The paper will curl and the quality of printing on plain paper will deteriorate significantly. When the amount of water exceeds 95% by weight, the stability of discharge from the nozzle orifice may deteriorate significantly.

The essential components of the ink of the present invention are as described above, but other general organic solvents used in conventionally known inks can also be used in combination.For example, organic solvents include methyl alcohol, ethyl alcohol, n-propyl alcohol, and isopropyl alcohol. Alkyl alcohols having 1 to 5 carbon atoms such as alcohol, n-butyl alcohol, 5ec-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, and n-pentanol; amides such as dimethylformamide and dimethylacetamide; acetone and diacetone Ketones or keto alcohols such as alcohol; ethers such as tetrahydrofuran and dioxane; oxyethylene or oxypropylene addition polymers such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, and polypropylene glycol ; Ethylene glycol, propylene glycol, trimethylene glycol, butylene glycol, 1. 2.
Alkylene glycols in which the alkylene group has 2 to 6 carbon atoms such as 6-hexanetriol and hexylene glycol; thiodiglycol; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether,
Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; lower dialkyl ethers of polyhydric alcohols such as nitriethylene glycol dimethyl (or ethyl) ether and tetraethylene glycol dimethyl (or ethyl) ether; sulfolane , N-methyl-2-pyrrolidone, 1.3-
Examples include dimethyl-2-imidazolidinone.

The content of the water-soluble organic solvent is generally 1 to 49% by weight, preferably 2 to 3% by weight based on the total weight of the ink.
The range is 0%.

When the above-mentioned media are used together, they can be used alone or as a mixture, but the most preferable liquid medium composition contains at least one water-soluble high-boiling organic solvent, such as a polyhydric alcohol such as diethylene glycol, triethylene glycol, or glycerin. It is something to do.

Various other dispersants, surfactants, viscosity modifiers, surface tension modifiers, fluorescent brighteners, etc. can also be added as necessary.

For example, viscosity modifiers such as polyvinyl alcohol, celluloses, and water-soluble resins; various cationic, anionic, or nonionic surfactants; surface tension modifiers such as jetanolamine and triethanolamine; pH modifiers using buffer solutions; Antifungal agents and the like can be mentioned.

Furthermore, the ink of the present invention solves the problem of ink bleeding when recorded on plain paper, dryness, and permeability of the recorded material, and from the aspect of matching with inkjet heads, the ink physical property is that the surface tension at 25°C is 30. to 68 d
It is desirable that the y n e /cm and viscosity be adjusted to 15 cP or less, preferably 1 ocP or less, more preferably 5 cP or less.

A suitable recording device for recording using the ink of the present invention includes a device that applies thermal energy corresponding to a recording signal to a recording liquid in a chamber of a recording head and generates droplets using the energy.

An example of the configuration of the head, which is the main part, is shown in FIG. 1(a).

(b), shown in FIG.

The head 13 includes a glass, ceramic, or plastic plate having grooves 14 through which ink passes, and a heat generating head 15 used for thermal recording (a thin film head is shown in the figure, but is not limited to this). Obtained by gluing. The heat generating head 15 includes a protective film 16 formed of silicon oxide or the like, aluminum electrodes 17-1. 17-2, a heating resistor layer 18 made of nichrome or the like, a heat storage layer 19, and a substrate 20 with good heat dissipation properties such as alumina.

The ink 21 has reached the discharge orifice 22, and the pressure P
A meniscus 23 is formed by this.

Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 suddenly generates heat, bubbles are generated in the ink 21 in contact with this area, and the pressure causes the meniscus 23 to protrudes, and the ink 21 becomes recording droplets 24 from the ejection orifice 22 and flies toward the recording medium 25. FIG. 2 shows an external view of a multi-head in which a large number of heads shown in FIG. 1(a) are arranged. The multi-head is made by adhering a glass plate 27 having multi-grooves 26 and a heating head 28 similar to that described in FIG. 1(a).

Note that FIG. 1(a) shows the head 13 along the ink flow path.
FIG. 1(b) is a sectional view taken along A-B in FIG. 1(a).
This is a cut plane along a line.

An example of an ink jet recording apparatus incorporating the head according to FIG. 3 is shown.

In FIG. 3, 61 is a blade as a wiping member, one end of which is held by a blade holding member and becomes a fixed end in the form of a cantilever. The blade 61 is disposed adjacent to the recording area of the recording head, and in this example, is held in a protruding form in the movement path of the recording head. A cap 62 is disposed at a home position adjacent to the blade 61, and is configured to move in a direction perpendicular to the direction of movement of the recording head and come into contact with the ejection port surface to perform capping. Furthermore, 63 is an ink absorber provided adjacent to the blade 61;
Like the blade 61, it is held in a protruding form in the movement path of the recording head. The blade 61 and cap 62
The absorber 63 constitutes an ejection recovery section 64, and the blade 61 and the absorber 63 remove moisture, dust, etc. from the ink ejection orifice surface.

Reference numeral 65 is a recording head that has an ejection energy generating means and performs recording by ejecting ink onto a recording material facing the ejection orifice surface on which ejection ports are arranged, and 66 is a recording head that mounts the print head 65 and moves the print head 65. It is a carriage for carrying out. The carriage 66 is slidably engaged with a guide shaft 67, and a portion of the carriage 66 is connected to a belt 69 (not shown) driven by a motor 68. This allows the carriage 66 to move along the guide shaft 67, allowing the recording head 65 to move the recording area and its adjacent area.

Reference numeral 51 denotes a paper feeding section for inserting a recording material, and 52 a paper feed roller driven by a motor (not shown). With these configurations, the recording material is fed to a position facing the ejection opening surface of the recording head, and as recording progresses, the recording material is discharged to a paper discharge section provided with a paper discharge roller 53.

In the above configuration, when the recording head 65 returns to the home position after recording ends, etc., the cap 6 of the head recovery section 64
2 is retracted from the moving path of the recording head 65, but the blade 61 protrudes into the moving path. As a result, the ejection port surface of the recording head 65 is wiped. Note that when the cap 62 contacts the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to protrude into the movement path of the recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are in the same position as the wiping position described above. As a result, even during this movement, the ejection orifice surface of the recording head 65 is wiped.

The above-mentioned movement of the print head to the home position is not limited to the end of printing or recovery of ejection, but also the movement of the print head to the home position adjacent to the print area at predetermined intervals while moving the print area for printing. However, along with this movement, the above-mentioned wiping is performed.

FIG. 4 is a diagram showing an example of an ink cartridge containing ink supplied to the head via an ink supply tube. Here, 40 is an ink bag containing supply ink, and a rubber stopper 42 is provided at the tip of the ink bag. By inserting a needle (not shown) into this plug 42,
The ink in the ink bag 40 can be supplied to the head. 44 is an ink absorber that receives waste ink.

The inkjet recording device used in the present invention includes:
The head and ink cartridge are not limited to separate units as described above, but a unit in which they are integrated as shown in FIG. 5 may also be suitably used.

In FIG. 5, 70 is an inkjet cartridge, which houses an ink absorber impregnated with ink. It is configured to be discharged as

Reference numeral 72 denotes an atmosphere communication port for communicating the inside of the cartridge with the atmosphere.

This inkjet cartridge 70 is used in place of the recording head 65 shown in FIG. 3, and is detachable from the carriage 66.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In the text, parts and percentages are based on weight unless otherwise specified.

After mixing the following ingredients and stirring for 5 hours, the pH was adjusted to 7.5 with a 0.1% aqueous solution of sodium hydroxide, and a membrane filter with a pore size of 0.22 microns was added. The inks A to E of the present invention were obtained by pressure filtration using Fluoropore Filter (trade name, manufactured by Sumitomo Electric Corporation).

Next, using the obtained inks A to E, an inkjet printer BJ130 that uses a heating element as an ink ejection energy source is used as an inkjet recording device.
(Product name: manufactured by Canon ■) was used to record on commercially available copy paper and bond paper, and the fixation of the resulting recorded material, the incidence of bleeding, and the clogging during reprinting after printing was stopped. The performance, clogging resistance during reprinting after a long printing stop, and frequency response were evaluated. The results are shown in Table 1.

The evaluation was normally performed at 25° C. and 60% RH.

Ink A C,1, Direct Yellow 86 2-Hydroxymethyl-1,3-propanediol 2 parts 17 parts 81 parts Ink B C,1, Acid Red 35 2-Hydroxymethyl-1,3-propanediol Glycerin water ink C C, 1, Food Black 2 Triethylene glycol 2-hydroxymethyl-1,3-propanediol Ethanol water ink D c, r, Direct Blue 199 Diethylene glycol 2-hydroxymethyl-1,3-propanediol n-
Butanol water 2.5 parts 4 parts 10 parts 2 parts 81.5 parts Ink E C, 1, Direct Black 154 2-Hydroxymethyl-1,3-propanediol Thiodiglycol Diethylene glycol Ethanol Water Sho Jl Yu JLij Examples 1 to Inks F to J of Comparative Examples 1 to 5 were obtained by treating all the components described below in the same manner as in Example 5, and various evaluations were performed in the same manner as in Examples. The results are shown in Table 1.

Ink FC, 1, Direct Yellow 86
2 part glycerin
17 parts water
81 parts ink G C, 1, food black 2
3-part triethylene glycol
12 parts ethanol
3 parts water
82 parts ink H c, r, direct blue 199
2.5M diethylene glycol
14 parts n-butanol
2 parts water
81.5 parts Ink IC, 1, Direct Black 154 PEG 300 Nonionic surfactant (trade name Nirasan Nonion 222
3 manufactured by Nippon Oil & Fats ■) Water ink JC, 1, Food black 2 Ethylene glycol isopropyl alcohol Water 2 parts 14 parts 0.5 parts 83.5 parts 3 parts 15 parts 2 parts 80 parts Measures - ± - Table Example ink ( 1”) Fixability (copy paper) (bond paper) (21) Smearing rate (copy paper) (bond paper) (3°) Clogging after printing stops (4°) After long-term printing stops Clogging resistance (5) Frequency-responsive printing ink (1) Fixability (copy paper) (bond paper) (2) Smearing rate (copy paper) (bond paper) (3) Printing - after time stop Clogging resistance (48) Clogging resistance after long-term printing stop (5°) Frequency response (de) Fixability evaluation 10 seconds after printing on commercially available copy paper and bond paper, 30
After a few seconds, the printed area was rubbed with a filter paper (trade name: No. 5 C, manufactured by Toyo Roshi ■).

◎...Fade in 10 seconds None○...Fade in 10 seconds Small △...Fade in 30 seconds Small ×...Fade in 30 seconds Large (2°) Regarding the incidence of blurring in the shape of dots, After printing 300 dots in a non-consecutive manner using a printer on commercially available copy paper or bond paper, the dots were left to stand for more than 1 hour, and then the number of dots that had bled was counted using a microscope and expressed as a percentage.

○: 10% or less △: 11 to 30% ×: 31% or more (31) Print - Clogging when reprinting after a time stop Print - For clogging when reprinting after a time stop, check the printer according to the specified settings. After filling the ink and printing alphanumeric characters continuously for 10 minutes, stop printing, leave it for 10 minutes without caps, etc., then print alphanumeric characters again and remove any gaps, missing characters, etc. Judgment was made based on the presence or absence of defective parts.

○No defects starting from the knee letter.

△A part of the knee letter is missing or missing.

×The knee character cannot be printed at all.

(4”) Recovery from clogging when reprinting after a long printing stop After filling the printer with the specified ink and printing alphanumeric characters continuously for 10 minutes, stop printing and leave the printer without a cap, etc. After leaving it for a day, we performed an operation to recover from the nozzle clogging, and determined how many times it took to print normally without any gaps or missing characters (60°C, 10 ± 5% R).
Leave it at H).

○: Normal printing is possible after 1 to 5 recovery operations.

△: Normal printing is possible after 6 to 10 recovery operations.

×: Normal printing is possible after 11 or more recovery operations.

(5'') Evaluation of Frequency Responsiveness The printing condition of the obtained printed matter, that is, the condition of smudges and white spots, and the condition of landing point defects such as splash and wobbling were observed and evaluated with the naked eye.

◎・・・The tracking ability of the ink to the frequency is good,
There are no spots, white spots, or poor impact points in both solid printing and character printing.

○: The followability of the ink to the frequency is almost good, and no casts, white spots, or poor landing points are observed in character printing, but a slight cast is observed in solid printing.

△: There are no clumsiness or white spots in character printing, but there are some poor impact points.

Also, in solid printing, there may be shadows or white spots. Approximately 1/3 of the entire solid pattern can be seen.

×: There are many spots and white spots in solid printing, and there are many spots and poor landing points in character printing.

[Effects] As explained above, the ink of the present invention has good foaming response to thermal energy, and can be used on copy paper,
Even on ordinary plain paper commonly used in offices such as report paper, notebooks, and stationery, it is possible to record with no bleeding, excellent quality, and good permeability.

Further, according to the present invention, it is possible to obtain ink that is highly safe even when used in offices and homes.

Further, according to the ink of the present invention, highly reliable recording can be performed without clogging of the nozzles of the inkjet head.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a longitudinal cross-sectional view and a cross-sectional view of a head section of an inkjet recording apparatus. FIG. 2 is an external perspective view of a multi-head head shown in FIG. 1. FIG. 3 is a perspective view showing an example of an inkjet recording apparatus. FIG. 4 is a longitudinal sectional view of the ink cartridge. FIG. 5 is a perspective view of the inkjet cartridge. 61: Wiping member 62: Cap 63: Ink absorber 64: Ejection recovery section 65: Recording head 66: Carriage fact 4-Include

Claims (4)

[Claims] (1) In the ink used in the inkjet recording method, in which thermal energy corresponding to the recording signal is applied to the ink to form ink droplets, and the droplets are applied to the recording material to perform recording, pigments are used. , water and 2-hydroxymethyl-1,
An ink characterized by containing 3-propanediol. (2) The ink according to claim 1, wherein the content of 2-hydroxymethyl-1,3-propanediol is in the range of 0.1 to 30% by weight based on the total weight of the ink. (3) In an inkjet recording method in which thermal energy corresponding to a recording signal is applied to ink to form ink droplets, and the droplets are applied to a recording material to perform recording, the ink contains pigment, water, and water. and 2-hydroxymethyl-1,3-propanediol. (4) The inkjet recording method according to (3), wherein the recording material is uncoated paper.