JPH06166844A - Oil-base white ink - Google Patents

Abstract

PURPOSE:To obtain the subject ink reduced in precipitation after the lapse of time and being therefore good in redispersibility and desirable for use in especially ink-containing writing utensils by compounding at least specified particles and an organic solvent. CONSTITUTION:The objective ink comprises hollow particles of a polymer, desirably a polyamide, an acrylic resin or an acryl/styrene copolymer as a white colorant, and an organic solvent (e.g. denatured alcohol), desirably selected from among alcohols, ketones and aromatic compounds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oily white ink. More specifically, the present invention relates to a white ink which has little sedimentation after aging and is particularly suitable for use in a writing instrument with a built-in ink.

[0002]

2. Description of the Related Art Conventionally, an oily white ink is composed of a white pigment, an organic solvent and a resin soluble in the organic solvent. Titanium oxide is used as the white pigment because of its whiteness.

By the way, since titanium oxide has a disadvantage that it has a large specific gravity and easily precipitates with time, when a white ink using titanium oxide is built in a writing instrument,
A stirring member such as a metal ball is built in the ink containing portion, and when used, the writing instrument is shaken up and down to re-disperse the titanium oxide that has settled by the stirring force of the stirring member, and has a thickening effect. By adding substances, the viscosity of the ink is increased to prevent the sedimentation of titanium oxide.

[0004]

[Problems to be Solved by the Invention] However, (1)
In the method using the above stirring member, in order to redisperse the precipitated titanium oxide, not only it is necessary to shake a large number of writing instruments, but also the stirring member does not move due to sediment and the titanium oxide cannot be redispersed. Relaxed
(2) When the viscosity of the ink is increased, there is a problem that the ink is not ejected from the pen tip. An object of the present invention is to obtain an oily white ink which is suitable for use in a writing instrument with a built-in ink, which has little sedimentation after aging and is suitable for use.

[0005]

DISCLOSURE OF THE INVENTION The gist of the present invention is an oil-based white ink containing at least a polymer hollow particle and an organic solvent.

The details will be described below. The polymer hollow particles are used as a coloring material. After writing, the hollow particles made of a polymer are white because the solvent inside the hollow particles evaporates and is replaced with air, so that light scattering occurs between the polymer layer which is the shell and the air inside so that it appears white. Can be used as a coloring material. As the polymer, polyamide, acryl, and acryl-styrene copolymer are preferable, and acryl-styrene copolymer is preferable in consideration of hardness of the shell.
An example of a commercially available product is SX863 (P) (manufactured by Nippon Synthetic Rubber Co., Ltd.). In addition, SX863 (A) and SX8 supplied in the form of water-based emulsions
64 (B), SX865 (B) (all manufactured by Nippon Synthetic Rubber Co., Ltd.), ROPAQUE OP42M, and OP6.
2. OP84 (Rohm and Haas, UK)
It is also possible to use such a thing. Of course, the water-based emulsion type is used after evaporating water into powder. The amount used is 1 to 40% by weight, more preferably 10 to 40% by weight based on the total amount of the oily white ink.
35% by weight.

Examples of the organic solvent include alcohol solvents such as methyl alcohol, ethyl alcohol, normal propyl alcohol, isopropyl alcohol, normal butyl alcohol and isobutyl alcohol, ketone solvents such as methyl ethyl ketone, methyl propyl ketone and methyl isobutyl ketone, toluene, Examples include aromatic solvents such as xylene.

In addition to the above components, titanium oxide, zinc oxide, aluminum oxide, lithopone, etc., which are usually used as white pigments, may be used as a coloring material. Furthermore, those conventionally used for oil-based inks can be appropriately selected and used according to the application. As the binder, polyvinyl butyral resin, polyvinyl pyrrolidone, rosin-modified maleic acid resin, acrylic resin, ketone resin, polyamide resin, polyvinyl methyl ether, or the like can be used, and other surfactants as wettability improvers, Propylene glycol monomethyl ether, cellosolve, carbitol, and a rust preventive can be added as a dryness adjusting agent.

The oily white ink according to the present invention can be easily prepared by agitating and mixing the above components using a commonly known stirrer when the polymer hollow particles are used alone as a colorant. When it is used in combination with a white pigment such as titanium oxide, it can be obtained by adding the other components to a dispersion of the white pigment in advance by a known disperser, followed by stirring and mixing.

[0010]

The oily white ink of the present invention contains polymer hollow particles as a coloring material. Since the hollow particles have a small specific gravity with respect to titanium oxide, little sedimentation occurs. Therefore, the viscosity of the ink is high. Since it can be kept low, there is little sedimentation over time, and it is presumed that it is particularly suitable for writing instruments.

[0011]

EXAMPLES The present invention will be described in more detail based on the following examples, but the numerical values in the examples of Table 1 and the comparative examples of Table 2 indicate “parts by weight”.

[0012]

[Table 1]

[0013]

[Table 2]

Description of Tables 1 and 2 (1) SX863 (P): hollow particle made of styrene-acrylic copolymer, average particle diameter 0.35 μm, manufactured by Nippon Synthetic Rubber Co., Ltd. (2) SX864 (B): styrene -Acrylic copolymer hollow particles Average particle size 0.45 µm, manufactured by Nippon Synthetic Rubber Co., Ltd., by evaporating water to give powder (3) ROPAQUE OP42M: Styrene-acrylic copolymer hollow particles An average particle diameter of 0.55 μm, manufactured by Rohm and Haas Co., Ltd. in the form of powder by evaporating water (4) ROPAQUE OP62: hollow particles made of styrene-acrylic copolymer Average particle size 0.4 μm, Rohm and UK Water vaporized powder from Haas Co. (5) Denka Butyral 2000L: Polyvinyl butyral, manufactured by Denki Kagaku Co., Ltd. (6) PVP K- 30: Polyvinylpyridone, manufactured by Kanto Chemical Co., Ltd. (7) Halon 110H: Ketone resin, Honshu Chemical Co., Ltd.
(8) Solmix AP-4: Denatured alcohol, Nippon Alcohol Sales Co., Ltd.

Production Method of Oily White Ink (Examples 1, 2 and 5) Each component was mixed with a well-known stirrer with blades.
An oily white ink was obtained by stirring for a time. (Examples 3 and 4, Comparative Examples 1 and 2) Titanium oxide and a binder were dispersed in a ball mill in a component, and the mixture was made into a paste to which other components were added and stirred for 2 hours to obtain an oily white color. I got ink.

The white inks obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were tested. The results are shown in Table 3.

[0017]

[Table 3]

[0018] * 1. Storage stability test 10cc of oily white ink in a test tube (15mm diameter) with a stopper
It was left to stand for 3 days, and after 3 days, the sedimentation state was visually evaluated. ○: No sedimentation △: Slight sedimentation ×: Sedimentation

* 2. Redispersibility test * 1. Make the same sample as in * 1, put one stirring ball (made of stainless steel) in them, and leave it for 3 months, then shake the test tube with a plug up and down until the stirring ball moves. Was measured.

[0020] * 3. Writability test A batting type marker (whiteboard marker: manufactured by Pentel Co., Ltd.) is filled with 4 cc of white ink, and the batting type marker is left to stand sideways until the ink penetrates into the pen tip.
Spiral handwriting was handwritten on the glass plate, and the handwriting was visually observed and judged. ◯: Good handwriting Δ: Slight blurring X: Scratching occurs

[0021]

As described above in detail, the oil-based white ink according to the present invention has less sedimentation with time and therefore has good redispersibility, and is particularly suitable for use in a writing instrument with a built-in ink. The oily white ink according to the present invention is
Other than a writing instrument, for example, it can be used as a so-called pen type using a brush, brush, etc., of course, a stamp ink,
It is a good ink that can be used as a recording ink, and can also be used as a white ink for jet printing, which has been difficult to put into practical use because an inorganic pigment has been used conventionally.

Claims (1)

[Claims] 1. An oil-based white ink comprising at least a polymer hollow particle and an organic solvent.