JPH07238243A - Recording ink - Google Patents

Abstract

PURPOSE:To obtain an ink useful for ink jet recording capable of obtaining stable, high-grade printings regardless of the kind of recording paper, also with no problem of safety. CONSTITUTION:This recording ink contains 1-12wt.% of a partially or fully saponified polyvinyl alcohol having 500-2500 in average polymerization degree. Another version of this recording ink contains 1-12wt.% of a partially or fully saponified polyvinyl alcohol having 500-2500 in average polymerization degree and 10-40wt.% of ethanol as solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording ink used in an ink jet recording apparatus, and more particularly to a recording ink capable of obtaining stable and high quality printing regardless of a recording medium.

[0002]

2. Description of the Related Art The ink jet recording system has a diameter of 20 to
Desired recording is made possible by a means for generating minute ink droplets of 150 μm and a means for causing the droplets to fly to a predetermined position on the recording medium. The liquid droplets are generated by ejecting a recording ink under pressure from a fine nozzle orifice having an inner diameter of about 15 to 150 μm, and the liquid droplets are recorded by applying an electric charge to the liquid droplets and operating an electric field. There are an electrostatic deflection type inkjet system in which a droplet is jetted to a predetermined position of a medium, a drop-on-demand inkjet system in which droplets are generated from a plurality of nozzle orifices only at a required position and directly jetted to a recording medium.

In any case, as a recording ink for ink jet recording, it is necessary that the recording medium has a sufficiently high print density and does not bleed, and the recording ink dries quickly after recording. It is desirable not to contaminate the surface of the recording medium. Conventionally, as a recording ink for ink jet recording, for example, JP-A-60-601 has been used.
No. 70, which comprises a liquid medium of polyhydric alcohol, lower alkyl ether, and nitrogen-containing 5-membered ring keto acid, and those whose surface tension is adjusted as shown in JP-A-63-213581 are known. In particular, in the case of enabling high-quality printing on plain paper, the recording ink contains a basic substance and the pH value of the recording ink is set to 12 to 14 as in JP-A-1-213376. It is known that at least one of the constituent fiber material, sizing material and surface treatment material is chemically dissolved to reduce the bleeding of recording ink on plain paper.

[0004]

However, JP-A 1-2
A recording ink capable of high-quality printing on plain paper as shown in No. 13376 is a recording ink containing a hydroxide of an alkali metal such as sodium hydroxide or potassium hydroxide as a basic substance. In addition, since the pH is 12-14 and strongly alkaline, when the user touches the recording ink directly or with the recording ink recorded on the surface of the recording paper, irritation peculiar to the skin or the like is caused to the skin. Therefore, it was difficult to ensure safety.

Further, when performing color printing using the above-described recording ink, it is necessary to add dyes of yellow color, magenta color, cyan color and the like to the recording ink. There is a problem that a desired color cannot be obtained because a strong alkali of 14 causes a chemical change and the absorption spectrum peculiar to the dye changes.

Furthermore, even if the recording ink as described above is used, it has no effect on recording on a transparent film used in an overhead projector or the like, and for this purpose, the recording ink is used. There is a problem in that a film dedicated to inkjet recording, which has been subjected to a special treatment on the surface so as not to flow, must be used.

Therefore, an object of the present invention is to solve the conventional problems as described above, to secure the safety for the user, and to have a high quality similarly to all recording media including transparent film or plain paper. It is an object to provide a recording ink capable of printing and also capable of color printing.

[0008]

In order to solve the above problems, in the present invention, a recording ink used in an ink jet recording apparatus which ejects from a nozzle for recording has a saponification rate of 75 to 97.5%. Partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol having a saponification rate of 97.5% or more is contained, and the average degree of polymerization of the above partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol is 500 to 3,000, particularly preferably. Is 1000 to 1800, and the amount of the partially saponified polyvinyl alcohol or the completely saponified polyvinyl alcohol contained in the recording ink is 0.5 to 15% by weight, particularly preferably 3 to 9% by weight. %
Is characterized in that.

Further, in the present invention, in the recording ink used in the ink jet recording apparatus for recording by jetting from the nozzle, the partially saponified polyvinyl alcohol having a saponification rate of 75 to 97.5% or the saponification rate of 97. 5
% Or more of completely saponified polyvinyl alcohol and 10 to 40% by weight, particularly preferably 10 to 35% by weight of ethanol as a solvent for dissolving the above partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol. It is characterized by doing.

[0010]

FUNCTION The structural formula of polyvinyl alcohol is shown below.

[0011]

[Chemical 1]

This is

[0013]

[Chemical 2]

It is produced by hydrolyzing polyvinyl acetate shown in (1) in alkali. Thus, the C of polyvinyl acetate
The one in which a part or all of the OOR group is replaced with an OH group is generally referred to as polyvinyl alcohol. Particularly, the one in which this replacement is performed for 97.5% or more is a completely saponified polyvinyl alcohol, less than 97.5%. The one adjusted for replacement may be referred to as partially saponified polyvinyl alcohol, and the solubility or viscosity in a solvent changes depending on the replacement ratio.

Regarding the solubility in water, the completely saponified polyvinyl alcohol has a characteristic that it swells in room temperature water at about 20 ° C. but hardly dissolves, and dissolves in warm water at 80 ° C. or higher. The lower the rate of substitution with OH groups, the higher the solubility in room temperature water.

Further, although it shows almost no solubility in solvents other than water, it shows solubility in a mixed solvent of water with respect to methanol and ethanol, and 40% with methanol and ethanol in a completely saponified polyvinyl alcohol. %, Which can be dissolved in a mixed solvent of about C
It has a characteristic that the lower the replacement ratio of the OOR group to the OH group, the more soluble it is in a mixed solvent having a high mixing ratio of methanol or ethanol.

An aqueous solution of fully saponified polyvinyl alcohol or partially saponified polyvinyl alcohol, or a mixed solution of water and an organic solvent exhibits high viscosity and adhesiveness, and the viscosity is a fully saponified polyvinyl alcohol contained in the solution. Alternatively, the higher the average degree of polymerization of partially saponified polyvinyl alcohol, the higher the content, and the higher the content, the higher the level.
The adhesive strength is greater as the rate of replacement of the completely saponified polyvinyl alcohol or the partially saponified polyvinyl alcohol in the solution from the COOR group to the OH group is lower, and the higher the content is.

In the recording ink of the present invention, the saponification ratio is 75.
To 97.5% of partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol having a saponification rate of 97.5% or more, and recording on a recording medium by utilizing the aforementioned characteristics By increasing the adhesiveness and further increasing the viscosity of the recording ink, bleeding and flow of the recording ink are suppressed, and high-quality printing can be performed without being affected by the type of recording medium.

As can be seen from the fact that polyvinyl alcohol is widely used as a synthetic paste and an additive when making paper from pulp, it is a very inexpensive material, and provides an inexpensive and safe recording ink. It is possible to
As described above, the recording ink according to the present invention ensures the safety for the user and is capable of high quality printing on any recording medium including a transparent film or plain paper. Since the chemical influence on the dye is extremely small, it is an inexpensive recording ink that enables color printing.

[0020]

EXAMPLES Hereinafter, examples of the present invention will be described, but these examples further specifically describe the present invention, and the embodiments are not limited thereto. (Example 1) C.I. which is a black dye. I. DirectB
A recording ink containing completely saponified polyvinyl alcohol was prepared using rack168.

The above C. I. DirectBlack1
The content of 68 was 3% by weight. For the completely saponified polyvinyl alcohol contained, four kinds of materials having different average degrees of polymerization were prepared as shown below, and the contents in the recording ink were 1% by weight, 3% by weight, 6% by weight, and 9% by weight, respectively. % By weight, 12
Each was adjusted to be a weight%.

Saponification rate 98.5% or more Average degree of polymerization about 500 (Unitika KK trade name UF-050G) Saponification rate 98.0 to 99.0% Average degree of polymerization about 1000 (Unitika Ltd. trade name) UF-100G) Saponification rate 98.0-99.0 Average degree of polymerization about 1700 (Unitika Ltd. product name UF-170G) Saponification rate 99.0% or more Average degree of polymerization about 2500 (Unitika Ltd. name) UF-250G) For comparison, a recording ink containing no completely saponified polyvinyl alcohol was also prepared.

The solvents of the above 21 kinds of recording inks are all water. Each of the recording inks adjusted as described above is suctioned and filled in an inkjet recording device, and is a plain paper PPC-K which is a general recording paper for electrophotography, which is generally called PPC. ) Product name) was recorded with dots.

The size of the opening of the nozzle orifice of the ink jet recording apparatus used in this embodiment is 25 μm in length.
It has a quadrilateral shape with a width of 40 μm and a diameter of 30-40 at a time.
It is possible to eject a recording ink droplet of about μm. Printing recording of 100 dots was performed with each recording ink, and the printed dots were observed with a microscope. The measurement results of the diameter and roundness of the printed dots are shown in FIG.

According to FIG. 1, all of the recording inks of the present invention containing completely saponified polyvinyl alcohol (abbreviated as PVA in FIG. 1) have a small diameter of 125 μm or less and a roundness of 1. Although high-quality printing and recording are being performed in the near future, the diameter of the recording ink containing no completely saponified polyvinyl alcohol for comparison is 110 to 140.
It has a large blur of μm and a roundness of 1.15.
Since the shape of the circle is 1.75, the shape of the circle is greatly broken, and high-quality printing cannot be expected.

Further, according to FIG. 1, in order to perform higher quality print recording, the average degree of polymerization of the completely saponified polyvinyl alcohol contained is particularly preferably 1000 or more,
The content is particularly preferably 3 to 12% by weight. As described above, it was confirmed that the recording ink of the present invention enables high-quality printing without bleeding or the like without being affected by the recording medium.

(Example 2) C.I. I. D
A recording ink containing partially saponified polyvinyl alcohol was prepared using erectBlack 168. The C. I. The content of DirectBlack 168 was 3% by weight.

For the partially saponified polyvinyl alcohol contained, three types of materials having different average degrees of polymerization were prepared as shown below, and the content in the recording ink was 1% by weight:
The amounts were adjusted to be 6% by weight, 6% by weight, 9% by weight and 12% by weight, respectively. Saponification rate 94.0-95.0% Average degree of polymerization about 500 (Unitika KK trade name UF-050MG) Saponification rate 95.5-97.5% Average degree of polymerization about 1700 (Unitika Ltd. trade name) UF-170MG) Saponification ratio 96.0-98.0 Average degree of polymerization about 2300 (Unitika KK trade name UF-230MG) A recording ink containing no partially saponified polyvinyl alcohol was also prepared for comparison.

The solvents of the above 16 kinds of recording inks are all water. Each of the recording inks adjusted as described above is suctioned and filled in an inkjet recording device, and is a plain paper PPC-K which is a general recording paper for electrophotography, which is generally called PPC. ) Product name) was recorded with dots.

The size of the opening of the nozzle orifice of the ink jet recording apparatus used in this embodiment is 25 μm in length,
It has a quadrilateral shape with a width of 40 μm and a diameter of 30-40 at a time.
It is possible to eject a recording ink droplet of about μm. Printing recording of 100 dots was performed with each recording ink, and the printed dots were observed with a microscope. The measurement results of the diameter and roundness of the printed dots are shown in FIG.

According to FIG. 2, the recording ink of the present invention containing partially saponified polyvinyl alcohol (abbreviated as PVA in FIG. 2) has a small diameter of 125 μm or less and a circularity of 1. Although high-quality printing and recording are being performed in the near future, the diameter of the recording ink containing no partially saponified polyvinyl alcohol for comparison is 110 to 140.
It has a large blur of μm and a roundness of 1.15.
Since the shape of the circle is 1.75, the shape of the circle is greatly broken, and high-quality printing cannot be expected.

Further, according to FIG. 2, the average degree of polymerization of the partially saponified polyvinyl alcohol contained is particularly preferably 1700 or more, in order to perform higher quality print recording.
The content is particularly preferably 3 to 12% by weight. As described above, it was confirmed that the recording ink of the present invention enables high-quality printing without bleeding or the like without being affected by the recording medium.

(Example 3) C.I. which is a blue dye. I. D
A recording ink containing partially saponified polyvinyl alcohol was prepared by using irectBlue199. The C. I. The content of DirectBlue199 was 3% by weight.

For the partially saponified polyvinyl alcohol to be contained, 5 kinds of materials having different average degrees of polymerization were prepared as shown below, and the content in the recording ink was 1% by weight: 3%.
The amounts were adjusted to be 6% by weight, 6% by weight, 9% by weight and 12% by weight, respectively. Saponification rate 87.0-89.0% Average degree of polymerization about 500 (Unitika Co., Ltd. trade name UP-050G) Saponification rate 86.0-90.0% Average degree of polymerization about 1000 (Unitika Ltd. trade name) UP-100G) Saponification rate 86.0-90.0 Average degree of polymerization about 1500 (Unitika Co., Ltd. trade name UP-150G) Saponification rate 87.0-89.0 Average degree of polymerization 1800 (Unitika Co., Ltd.) Trade name UP-180G) Saponification rate 87.0-89.0% Average degree of polymerization about 2400 (Unitika Co., Ltd. trade name UP-240G) Also, for comparison, recording inks containing no partially saponified polyvinyl alcohol are used. It was adjusted.

The solvents of the above 26 kinds of recording inks are all water. Each of the recording inks adjusted as described above is suctioned and filled in an inkjet recording device, and is a plain paper PPC-K which is a general recording paper for electrophotography, which is generally called PPC. ) Product name) was recorded with dots.

The size of the opening of the nozzle orifice of the ink jet recording apparatus used in this example is 25 μm in length.
It has a quadrilateral shape with a width of 40 μm and a diameter of 30-40 at a time.
It is possible to eject a recording ink droplet of about μm. Printing recording of 100 dots was performed with each recording ink, and the printed dots were observed with a microscope. The measurement results of the diameter and roundness of the printed dots are shown in FIG.

According to FIG. 3, the recording ink of the present invention containing partially saponified polyvinyl alcohol (abbreviated as VPA in FIG. 3) has a small diameter of 120 μm or less and a roundness of 1. Although high-quality printing and recording have been performed in the near future, the diameter of the recording ink containing no completely saponified polyvinyl alcohol for comparison is 110 to 145.
It has a large blur of μm and a roundness of 1.15.
The shape of the circle is 1.80 and the shape of the circle is greatly broken, and high-quality printing cannot be expected.

Further, according to FIG. 3, in order to carry out print recording with higher image quality, the average degree of polymerization of the partially saponified polyvinyl alcohol contained is particularly preferably 1,000 or more,
The content is particularly preferably 3 to 12% by weight. As described above, it was confirmed that the recording ink of the present invention enables high-quality printing without bleeding or the like without being affected by the recording medium.

Example 4 A black dye C.I. I. D
A recording ink containing completely saponified polyvinyl alcohol and ethanol was prepared using erectBlack 168. The C. I. DirectBlack1
The content of 68 was 3% by weight.

As the completely saponified polyvinyl alcohol to be contained, two kinds of materials having different average degrees of polymerization are prepared as shown below, and the content in the recording ink is 1% by weight, 5% by weight and 10% by weight. Each was adjusted so that Saponification rate 98.0-99.0% Average degree of polymerization about 1000 (Unitika Ltd. trade name UF-100G) Saponification rate 98.0-99.0 average degree of polymerization about 1700 (Unitika Ltd. trade name UF) -170G) The content of ethanol is 10 in the recording ink.
The amounts were adjusted to be 20% by weight, 20% by weight, and 35% by weight, respectively, and a recording ink containing no ethanol was also prepared for comparison.

The solvent of the above 24 kinds of recording ink is water except for ethanol. Each of the recording inks adjusted as described above is sucked and filled in an inkjet recording device, and a plain paper PPC-which is a general recording paper for electrophotography, which is generally called PPC.
Dot recording was performed on K (trade name of Daishowa Paper Manufacturing Co., Ltd.).

The size of the opening of the nozzle orifice of the ink jet recording apparatus used in this embodiment is 25 μm in length,
It has a quadrilateral shape with a width of 40 μm and a diameter of 30-40 at a time.
It is possible to eject a recording ink droplet of about μm. The size of the plain paper PPC-K used in this embodiment is 2
It has a quadrilateral shape of 10 mm x 297 mm.

Plain recording paper PPC with each recording ink
-180 mm x 267 m leaving 15 mm from each side of -K
In the range of m, the interval between the centers of the dots was set to 141 μm to perform solid printing, and the undulated state and curled state of the plain paper PPC-K after printing are shown in FIG.

The undulations in FIG. 5 are those in which the surface irregularities are large and undulating, x, those in which the surface has irregularities and undulations, and those in which there are almost no surface irregularities and sigma, Those having no unevenness and no waviness on the surface are indicated by ⊚. In the curled state in FIG. 5, as shown in FIG. 4, the length of the plain paper PPC-K in the long side direction is L, one short side is fixed to a plane, and the other short side is the above-mentioned. The height floating from the plane is defined as V, and the ratio is expressed as a percentage of V and L.

According to FIG. 5, with the recording ink of the present invention containing completely saponified polyvinyl alcohol (abbreviated as VPA in FIG. 5) and ethanol, the waviness is generated even under difficult printing conditions such as solid printing on the entire surface. It can be seen that there is no curl and there is very little curl and high-quality printing is performed, but the recording ink for comparison, which does not contain ethanol, has large undulations and curls, resulting in poor quality.

As described above, in the recording ink of the present invention, the inclusion of completely saponified polyvinyl alcohol enables not only high quality printing but also the inclusion of ethanol enhances the quality of the recording paper after printing. I confirmed that is possible. (Example 5) C.I. I. DirectB
A recording ink containing partially saponified polyvinyl alcohol and ethanol was prepared using rack168.

The above C. I. DirectBlack1
The content of 68 was 3% by weight. The partially saponified polyvinyl alcohol contained has an average degree of polymerization of 1 as shown below.
Material having a saponification ratio of 700 and a saponification ratio of 95.5 to 97.5% (Unitika Co., Ltd., trade name UF-170MG), and the content in the recording ink is 1% by weight, 5% by weight, and 10% by weight. Adjusted to.

The content of ethanol was adjusted so that the content in the recording ink was 10% by weight, 20% by weight, and 35% by weight, and the recording ink containing no ethanol was also prepared for comparison. The solvent of the above 12 kinds of recording ink is water except for ethanol.

Each of the recording inks adjusted as described above is sucked and filled in the ink jet recording apparatus,
Dot recording was performed on plain paper PPC-K (trade name of Daishowa Paper Manufacturing Co., Ltd.), which is a general recording paper for electrophotography generally called PPC. The size of the opening of the nozzle orifice of the ink jet recording apparatus used in this example is 25 in length.
It has a quadrangle with a width of 40 μm and a diameter of 30 μm at a time
It is possible to eject recording ink droplets of approximately 40 μm. Further, the size of the plain paper PPC-K used in this embodiment is a quadrangle of 210 mm × 297 mm.

Plain paper PPC with each recording ink
-180 mm x 267 m leaving 15 mm from each side of -K
In the range of m, the interval between the centers of the dots was set to 141 μm to perform solid printing, and the undulated state and curled state of the plain paper PPC-K after printing are shown in FIG.

The evaluation of the undulation state in FIG. 6 is the same as that shown in (Example 4). The evaluation of the curl state in FIG. 6 is also as shown in FIG. According to FIG. 6, with the recording ink of the present invention containing partially saponified polyvinyl alcohol and ethanol, there is no waviness, very little curling, and high quality even under difficult printing conditions such as solid printing on the entire surface. Printing is done,
It can be seen that in the comparative recording ink containing no ethanol, the waviness and curl are large and the quality is deteriorated.

As described above, in the recording ink of the present invention, the inclusion of partially saponified polyvinyl alcohol enables not only high quality printing but also the inclusion of ethanol enhances the quality of the recording paper after printing. I confirmed that is possible. (Example 6) C.I. which is a blue dye. I. DirectB
The recording ink containing partially saponified polyvinyl alcohol and ethanol was prepared using lue199.

The above C. I. DirectBlue19
The content of 9 was 3% by weight. For the partially saponified polyvinyl alcohol to be contained, two kinds of materials having different average degrees of polymerization are prepared as shown below so that the content in the recording ink becomes 1% by weight, 5% by weight and 10% by weight. Adjusted to each.

Saponification rate 86.0-90.0% Average degree of polymerization about 1000 (Unitika Ltd. trade name UP-100G) Saponification rate 87.0-89.0 Average degree of polymerization about 1800 (Unitika Ltd.) Trade name UF-180G) The content of ethanol is 10 in the recording ink.
The amounts were adjusted to be 20% by weight, 20% by weight, and 35% by weight, respectively, and a recording ink containing no ethanol was also prepared for comparison.

The solvents of the above 24 kinds of recording inks are all water except ethanol. Each of the recording inks adjusted as described above is sucked and filled in an inkjet recording device, and a plain paper PPC-which is a general recording paper for electrophotography, which is generally called PPC.
Dot recording was performed on K (trade name of Daishowa Paper Manufacturing Co., Ltd.).

The size of the opening of the nozzle orifice of the ink jet recording apparatus used in this embodiment is 25 μm in length,
It has a quadrilateral shape with a width of 40 μm and a diameter of 30-40 at a time.
It is possible to eject a recording ink droplet of about μm. The size of the plain paper PPC-K used in this embodiment is 2
It has a quadrilateral shape of 10 mm x 297 mm.

Plain recording paper PPC with each recording ink
-180 mm x 267 m leaving 15 mm from each side of -K
In the range of m, the interval between the centers of the dots is set to 141 μm to perform solid printing, and the undulated state and curled state of the plain paper PPC-K after printing are shown in FIG. 7.

The evaluation of the undulation state in FIG. 7 is the same as that shown in (Example 4). The evaluation of the curl state in FIG. 7 is also as shown in FIG. According to FIG. 7, in the recording ink of the present invention containing partially saponified polyvinyl alcohol and ethanol, there is no waviness, very little curling, and high quality even under difficult printing conditions such as solid printing on the entire surface. Printing is done,
It can be seen that in the comparative recording ink containing no ethanol, the waviness and curl are large and the quality is deteriorated.

As described above, in the recording ink of the present invention, the inclusion of partially saponified polyvinyl alcohol enables not only high-quality printing, but also the inclusion of ethanol enhances the quality of the recording paper after printing. I confirmed that is possible. As described in each of the above examples, in the recording ink of the present invention, the average degree of polymerization is 500 to 2
500, other characteristics such as the possibility of nozzle clogging caused by an increase in the viscosity due to an increase in the average degree of polymerization, particularly preferably in the range of 1000 to 1800, and a saponification ratio of 75 to 97. Use of 5% partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol having a saponification rate of 97.5% or more at a content of 1 to 12% by weight, particularly preferably 3 to 12% by weight. High quality ink jet recording is possible without being affected by the type of recording medium used.

In the recording ink of the present invention, that is, the recording ink containing 1 to 12% by weight of partially saponified or fully saponified polyvinyl alcohol having an average degree of polymerization of 500 to 2500, the above partial saponification is used. The inclusion of ethanol as a solvent that dissolves the fully or fully saponified polyvinyl alcohol does not affect the diameter and roundness of the printed dots.

Further, from FIGS. 5 to 7, it is inferred that the waviness and curl of the recording medium are good up to an ethanol content of about 40%. Therefore, in the recording ink of the present invention, the average degree of polymerization is 500 to 300.
1 to 12% by weight of partially saponified polyvinyl alcohol having a saponification rate of 75 to 97.5% or a fully saponified polyvinyl alcohol having a saponification rate of 97.5% or more in the range of 0, particularly preferably 1000 to 1800. , Particularly preferably in a content of 3 to 12% by weight, as a solvent for dissolving the above-mentioned partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, 10 to 40% by weight, particularly preferably 10 to 35% by weight The inclusion of the above-mentioned ethanol not only enables high-quality inkjet recording without being affected by the type of recording medium, but it also consists of natural pulp like plain paper, and the quality of the paper itself deteriorates due to water absorption. For recording media that are easy to
High-quality inkjet recording is possible.

In this embodiment, the black and blue recording inks have been described as an example, but it goes without saying that the effects of the present invention are the same for inks of other colors.

[0063]

INDUSTRIAL APPLICABILITY In the recording ink of the present invention, a partially saponified polyvinyl alcohol having an average degree of polymerization of 500 to 2500, particularly preferably 1000 to 1800 and a saponification rate of 75 to 97.5%, or saponification is used. Rate 97.
By containing 5% or more of completely saponified polyvinyl alcohol in an amount of 1 to 12% by weight, particularly preferably 3 to 12% by weight, a high-quality inkjet is not affected by the type of recording medium used. There is an effect that recording is possible. .

Further, in the recording ink of the present invention,
Average degree of polymerization 500 to 2500, particularly preferably 100
Saponification rate in the range of 0 to 1800 75 to 97.5%
Partially saponified polyvinyl alcohol or saponification rate 9
1% of fully saponified polyvinyl alcohol of 7.5% or more
Content of 1 to 12% by weight, particularly preferably 3 to 12% by weight, as a solvent for dissolving the above partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, 10 to 40% by weight, particularly preferably 10
By containing 35% by weight to 35% by weight of ethanol, not only high quality ink jet recording is possible without being affected by the type of recording medium, but it is also made of natural pulp like plain paper and the paper itself absorbs moisture. There is an effect that high quality ink jet recording is possible even on a recording medium whose quality is likely to deteriorate.

[Brief description of drawings]

FIG. 1 is a list showing the measurement results of print dots of Example 1 using a recording ink of the present invention.

FIG. 2 is a list showing the measurement results of print dots of Example 2 using the recording ink of the present invention.

FIG. 3 is a list showing the measurement results of print dots of Example 3 using the recording ink of the present invention.

FIG. 4 is a diagram showing examples 4, 5 in which the recording ink of the present invention is used.
6 is a conceptual diagram illustrating a method of calculating the amount of curl used in FIG.

FIG. 5 is a list showing the state of the recording paper after printing in Example 4 using the recording ink of the present invention.

FIG. 6 is a list showing the state of the recording paper after printing in Example 5 using the recording ink of the present invention.

FIG. 7 is a list showing the state of the recording paper after printing in Example 6 using the recording ink of the present invention.

[Explanation of symbols]

 1 Flat 2 Recording paper after printing 3 Fixed edge

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Masayoshi Shiraishi 6-31-1, Kameido, Koto-ku, Tokyo Seiko Electronics Industry Co., Ltd.

Claims (3)

[Claims] 1. A recording ink used in an ink jet recording apparatus which ejects from a nozzle to perform recording, wherein a partially saponified polyvinyl alcohol having a saponification rate of 75 to 97.5% or a saponification rate of 97.5% or more. A recording ink containing completely saponified polyvinyl alcohol. 2. The partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol contained has an average degree of polymerization of 500 to 2500, and the content of the partially saponified polyvinyl alcohol or the completely saponified polyvinyl alcohol is 1 to 12. The recording ink according to claim 1, wherein the recording ink is wt%. 3. The recording ink according to claim 1, which contains 10 to 40% by weight of ethanol as a solvent.