JP2019147929A - Irreversible display ink for aqueous brush writing paper - Google Patents

Abstract

To provide an irreversible display ink for aqueous brush writing paper.SOLUTION: An irreversible display ink for aqueous brush writing paper contains a nonvolatile liquid having a 23°C viscosity of 500 mPa s or more and 100,000 mPa s or less.SELECTED DRAWING: None

Description

  The present invention relates to an ink for forming an irreversible display on water pen paper that can be repeatedly written with water.

The water brush paper is a specially processed paper that can be repeatedly written with a brush or the like (Patent Document 1). Waterbrush paper is a colored layer obtained by applying and drying a color material such as black together with a binder on the base paper, and the outermost surface obtained by applying and drying a white low refractive index pigment with a binder. Positioned white layers are stacked in this order.
The waterbrush paper has a large refractive index difference between the white layer pigment and air, and light scatters, so that the appearance when dried is white. When the water brush paper gets wet, the water fills the gaps between the pigments in the white layer. Then, since the refractive index difference between the pigment and water is small, the light is not scattered in the white layer, the concealing property of the white layer is lowered, and the color tone of the colored layer located under the white layer appears and the color tone is revealed. Change. Then, the water pen paper wetted with water permeates or evaporates with time and disappears from the white layer, so that the white layer returns to white tone and is restored to the water pen paper before writing.
Utilizing such performance, the waterbrush paper is used for practicing brush calligraphy and toys for children.

On the other hand, there is also a desire to permanently store an image formed on waterbrush paper. Patent Document 2 discloses a solid object having a refractive index of 1.3 to 1.8 and showing a solid state at 20 ° C. A composition obtained by dissolving / dispersing has been proposed.
The invention described in Patent Document 2 requires uniform dissolution of the solid material or refinement of the solid material and dispersion stability so that the solid material can enter the fine gaps existing between the pigments.

JP 2012-206491 A JP 2005-15777 A

  An object of the present invention is to provide an irreversible display ink for water pen paper.

Means for solving the problems of the present invention are as follows.
1. An irreversible display ink for waterbrush paper, comprising a non-volatile liquid having a viscosity of 500 mPa · s or more and 100,000 mPa · s or less at a temperature of 1.23 ° C.
2. Viscosity at 23 ° C. is 30 mPa · s or more and 300 mPa · s or less. Irreversible display ink for water pen paper described in 1.
3. The non-volatile liquid is a dry oil. Or 2. Irreversible display ink for water pen paper described in 1.

  The irreversible display ink for water pen paper according to the present invention fills the gaps between the pigments of the water pen paper with a non-volatile liquid and does not contain a solid material, so that it is easy to manufacture and has excellent storage stability. The irreversible display ink for water pen paper of the present invention preserves an image with a non-volatile liquid, but since the non-volatile liquid has a high viscosity, there is little flow on the water pen paper and the shape of the image changes with time. Can be suppressed.

  The present invention relates to an irreversible display ink for water pen paper containing a non-volatile liquid having a viscosity at 23 ° C. of 500 mPa · s to 100,000 mPa · s.

"Non-volatile liquid"
In the present invention, the nonvolatile liquid means a compound that is liquid at 20 ° C. and does not boil at 1 atm 150 ° C.
The non-volatile liquid used for the irreversible display ink for water pen paper of the present invention is characterized in that the viscosity at 23 ° C. is 500 mPa · s or more and 100,000 mPa · s or less. When the viscosity is less than 500 mPa · s, the fluidity of the non-volatile liquid is large, and the formed image is deformed due to bleeding over time. Further, if this viscosity is greater than 100,000 mPa · s, the amount of volatile solvent to be added in order to obtain a viscosity suitable for ink increases, so the shape at the time of application comprising a non-volatile liquid and a volatile solvent The difference between the volatile solvent volatilized and the shape after drying consisting only of a non-volatile liquid becomes large. The viscosity at 23 ° C. is more preferably 4,000 mPa · s or more and 50,000 mPa · s or less, and further preferably 8,000 mPa · s or more and 30,000 mPa · s or less.

  The non-volatile liquid used in the present invention can be used without particular limitation as long as it satisfies the above-mentioned viscosity, for example, dry oil such as polymerized linseed oil and polymerized dehydrated castor oil, and non-drying oil such as castor oil. , Nonionic surfactants having a freezing point of less than 20 ° C. (polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene-polyoxypropylene-alkyl ether, polyoxyalkylene ether, polyoxyethylene monoalkyl ester, sorbitan monoalkyl Ester, polyoxyethylene sorbitan monoalkyl ester, glycerin mono fatty acid ester, polyoxyethylene glycerin mono fatty acid ester, polyglycerin alkyl ester, polyalkylene glycol derivative and the like). Among these, drying oil is particularly preferable because it is solidified by oxidative polymerization with oxygen in the air over time, and therefore, there is little bleeding, stickiness, etc., and an image can be stably stored.

"Irreversible display ink for water pen paper"
The irreversible display ink for ink brush paper of the present invention preferably has a viscosity at 23 ° C. of 30 mPa · s or more and 300 mPa · s or less as the whole ink. When the viscosity of the ink as a whole is within the above-described range, the writing feeling with a brush is excellent. Note that the viscosity of the irreversible display ink for ink brush paper of the present invention as a whole is not limited to the above range. For example, when an image is formed with a stamp or the like, the viscosity is higher than 300 mPa · s and 5000 mPa. -It can also be made into s or less.

"Volatile solvent"
In order to adjust the viscosity of the ink as a whole to 30 mPa · s or more and 300 mPa · s or less, a volatile solvent may be added to dilute a high-viscosity nonvolatile liquid. Under the present circumstances, it is preferable that the addition amount of a volatile solvent is 200 mass parts or less with respect to 100 mass parts of non-volatile liquids. When the addition amount of the volatile solvent with respect to 100 parts by mass of the non-volatile liquid is more than 200 parts by mass, the amount of the volatile solvent to be added becomes too large, and the shape at the time of application consisting of the non-volatile liquid and the volatile solvent, The difference with the shape after drying which consists only of a non-volatile liquid will become large. In addition, in this invention, a volatile solvent means the compound whose boiling point is 130 degrees C or less.

  The volatile solvent used in the present invention can be used without any particular limitation on water and organic solvents. Examples of the organic solvent include alcohols such as methanol, ethanol, n-propanol, and isopropanol, hydrocarbons such as n-hexane, n-heptane, and n-octane, propyl formate, butyl formate, propyl acetate, and butyl acetate. Ester series, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexanone, methyl isobutyl ketone and other ketone series, ethylene glycol monomethyl ether and other ether series, and the like can be used. In order to adjust the fragrance of the volatile solvent, a small amount of liquid fragrance (limonene, linalool, citral, etc.) that is liquid at 20 ° C. can be added.

The present invention will be specifically described below with reference to examples. However, the present invention is not limited to these.
"Experiment 1"
Nonvolatile liquids shown in Table 1 below were used as samples. The viscosity of each sample was measured using a Brookfield viscometer (B type viscometer, manufactured by Tokyo Keiki Co., Ltd.) at 23 ° C. 3 or No. Measurement was performed at a rotational speed of 6 rpm using a No. 4 rotor. As the refractive index, a value of 20 ° C. in the sodium D line (589 nm) is described. In addition, each sample was used as a paint, and kana characters were written on a commercially available water pen paper CA black (manufactured by Nippon Paper Papillia Co., Ltd.) using a brush pen for water brush paper (manufactured by Kuretake Co., Ltd.). Evaluation was made in three stages. Table 1 shows the evaluation results. In addition, the water brush paper CA black uses art paper as a base paper, a black base layer composed of a black pigment and a binder resin emulsion is provided on one side, and a porous material composed of a pigment such as fine particle silica and a binder resin emulsion on the black base layer. It is a multilayer coated paper having a configuration in which a white layer is laminated.

"Writability"
○: Appropriate viscosity and good carrying when writing.
X: Viscosity is high, resistance is large when writing, and fading occurs.
XX: Viscosity is very high and difficult to include in a brush.
"Bludge"
○: The original shape is maintained without bleeding even after 24 hours of writing.
X: After 24 hours of writing, it spreads due to bleeding and the original shape is not maintained.

Samples 1 to 6 having a viscosity of 500 mPa · s or more and 100,000 mPa · s or less had high viscosity and had some difficulty in writing, but the written letters maintained the shape as they were without blurring.
Samples 7 to 11 having a viscosity of less than 500 mPa · s were excellent in writing property, but the written characters spread over time and the original shape could not be maintained.
The sample 12 having a viscosity larger than 100,000 mPa · s has a high viscosity and was difficult to be included in the brush. In addition, since the sample 12 was not able to be written, the blur evaluation was not performed.

"Experiment 2"
If necessary, a volatile solvent was added to the non-volatile liquid used in Experiment 1 to adjust the viscosity, thereby preparing irreversible display inks for waterbrush paper of Examples and Comparative Examples. Examples, types of volatile solvents added to irreversible display inks for each ink brush paper in comparative examples, parts by mass of volatile solvent added to 100 parts by mass of nonvolatile liquid, viscosity of ink (B-type viscometer, rotation Several 60 rpm, No. 2 rotor used, value at 23 ° C.). Moreover, the following evaluation was performed using each sample and commercially available waterbrush paper CA black (made by Nippon Paper Industries Papiria Co., Ltd.). Table 2 shows the evaluation results.

"Writability"
Kana characters were written on a water pen paper CA black (manufactured by Nippon Paper Industries Co., Ltd.) using a brush pen for water brush paper (manufactured by Kuretake Co., Ltd.), and the writing property was evaluated in the following three stages.
○: Appropriate viscosity and good carrying when writing.
Δ: Low viscosity and dripping from the brush occurs.
X: Viscosity is high, resistance is large during writing and fading occurs.

"Concentration maintenance"
Using a small desktop printing tester (manufactured by RK Print Coat Instrument Co., Ltd.) equipped with a gravure plate (plate size 106 x 155 mm, solid plate), for each of the ink brush papers of the examples and comparative examples on CA black paper The irreversible display ink was solid-printed by a gravure coating method, and then dried to evaporate a volatile solvent, thereby producing a coated paper having a non-volatile liquid adhesion amount of 12 to 17 g / m ² .
About the part which developed color by the non-volatile liquid adhesion, the color density was visually observed immediately after coating, 4 hours later, 1 day later and 30 days later, and evaluated in the following three stages.
○: The color image density is the same as that immediately after color development.
(Triangle | delta): Although a color development image becomes light color, it can visually recognize.
X: The colored image is extremely light and difficult to view.

"Area change rate"
About the sample which carried out the gravure coating, the color development area was measured from the picked-up image of a color development part using the image-analysis apparatus (Dot Analyzer DA-5000S type, Oji Scientific Instruments Co., Ltd. make). From the measured color development area, the area change rate was calculated by the following formula.
Area change rate (%) = colored area after 4 hours of coating / area of gravure plate × 100

"Shape maintenance"
For Kana characters written with gravure-coated samples and brush pens for water brush paper (manufactured by Kuretake Co., Ltd.), the shape of the portion colored by non-volatile liquid adhesion was visually observed after 4 hours, 1 day and 30 days after coating. In comparison with the shape immediately after coating, the following three stages were evaluated.
○: The visual shape is the same as that immediately after color development.
Δ: Slight deformation is observed in the visual shape.
X: A big change is seen in a visual shape.

  Examples 1 to 9 in which the viscosity at 23 ° C. of the irreversible display ink is 30 mPa · s or more and 300 mPa · s or less were excellent in writing property with a brush. Moreover, Examples 1-5 containing the non-volatile liquid whose viscosity in 23 degreeC is 9900 mPa * s-17,600 mPa * s were excellent in shape maintainability, and were able to maintain the same image after 30 days.

Comparative Examples 1 and 4 to 8 in which the viscosity at 23 ° C. of the irreversible display ink was 30 mPa · s or more and 300 mPa · s or less were excellent in writing property with a brush. However, in Comparative Examples 1, 4 to 7, the viscosity at 23 ° C. of the non-volatile liquid contained was as small as less than 500 mPa · s and spread over time, so the area change rate was as large as 120% or more and the shape could not be maintained. In Comparative Example 8, since the amount of water, which is a volatile solvent, is large, the character is thinned by volatilization of water, the outline is partially lost, the area of the colored portion is reduced, and the area changes The rate changed below 100% and the shape changed.
In Comparative Example 2 having a viscosity at 23 ° C. larger than 300 mPa · s, the resistance was large and the blur occurred when writing with a brush.
In Comparative Examples 3 and 9 having a viscosity at 23 ° C. of less than 30 mPa · s, dripping from the brush occurred. Further, Comparative Examples 3 and 9 have a large amount of n-heptane or water which is a volatile solvent to be contained, so that when these are volatilized, the characters become thin, and the color-developing region and the decolored portion inside Occurred, the area change rate was significantly less than 100%, and the shape immediately after color development could not be maintained.

Claims (3)

  An irreversible display ink for waterbrush paper, comprising a non-volatile liquid having a viscosity at 23 ° C. of 500 mPa · s to 100,000 mPa · s.   The irreversible display ink for waterbrush paper according to claim 1, wherein the viscosity at 23 ° C is from 30 mPa · s to 300 mPa · s.   The irreversible display ink for pen paper according to claim 1 or 2, wherein the non-volatile liquid is a dry oil.