JPH01188576A - Ink composition for board marker - Google Patents

Abstract

PURPOSE:To obtain the subject ink composition for use to a white board, electronic blackboard, etc., having no problem about odor and toxicity, having excellent erasability, by mixing a coloring agent with a specific binding agent, release agent and water-insoluble inorganic powder in a specific ratio and using water as a dispersing medium. CONSTITUTION:Water is used as a dispersing medium and 0.1-8wt.%, preferably 0.2-5wt.% calculated as solid content of a coloring agent is mixed with 2-10wt.%, preferably 2-6wt.% binding agent comprising a water-soluble synthetic resin consisting essentially of PVA of <=1000 degree of polymerization, 5-10wt.% release agent having a surfactant silicone base [preferably a copolymer of the formula (R<1> is alkylene; R<2> is alkyl or H; m and n >=1; a and b>=0 and at least one of the both is >=1)] and 0.2-8wt.% water-insoluble inorganic powder (preferably one having 10-40 milli mum average particle diameter of primary particle and silicon dioxide is preferable) to afford the aimed composition.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applicable to whiteboards, electronic blackboards, etc.
A board that allows you to write on a smooth ink-permeable writing surface made of wax, metal, glass, plastic, plastic laminated paper, etc., and erase the dry handwriting by gently wiping it with a regular blackboard eraser or cloth material. The present invention relates to an ink composition for markers.

[Prior art and its problems]

BACKGROUND ART In recent years, water-based inks have been increasingly used in general writing instruments with penetrating pen cores, such as marking pens and felt-tip pens, instead of oil-based inks that are problematic due to the toxicity and flammability of organic solvents. Such a water-based ink has a basic composition in which a pigment, a water-soluble resin, and a dispersant are contained in an aqueous solvent containing a water-soluble organic solvent.

However, oil-based inks using highly volatile organic solvents such as ketone, ester, and alcohol-based solvents are still used as inks for board markers, which are writing tools used on whiteboards and electronic blackboards, and water-based inks are still being used. It has not been put into practical use.

This is because on whiteboards and electronic blackboards, handwriting is erased many times and the same writing surface is used over and over again. It must be able to be erased without leaving any traces, which means that unlike inks for regular writing instruments such as marking pens, it has a unique ability to not stick to the writing surface and is easy to peel off, and erasing is often done immediately after writing. However, with water-based inks, it is difficult to provide good releasability and quick-drying properties, and drying is delayed, especially in high humidity environments, and once dry handwriting becomes wet, making erasability worse. A major factor is that it has some drawbacks. Also, since the writing surface mentioned above is very smooth,
Water-based inks have difficulty in producing beautiful lines due to the high surface tension of the water, which is one of the reasons for the inability to put them into practical use.

Therefore, current board markers that use oil-based ink are commonly used for commercial purposes such as offices and factories, but are not suitable for use in educational settings or homes due to the odor, toxicity, and flammability characteristic of organic solvents. There were also problems, and because it was highly volatile, if you forgot to tighten the cap, the pen core would quickly dry up and become unusable.

[Means for solving problems]

In order to solve the above-mentioned conventional problems, the inventor conducted detailed research over many years to create a water-based board marker ink that could replace oil-based inks. The basic composition contains a certain blending ratio of a release agent and a release agent↓A water-based ink containing a specific powder has sufficient erasability and quick-drying properties for practical use as a board marker, and is particularly effective under high humidity conditions. It was discovered that the pen has excellent erasability, good stability over time, and is less likely to cause dry-up of the pen core, leading to the creation of this invention.

That is, this invention uses water as a dispersion medium, a coloring agent of 0.1 to 8% by weight in terms of solid content, and a binder made of a water-soluble synthetic resin mainly composed of polyvinyl alcohol with a degree of polymerization of 1° OOO or less. 10% by weight, 5-18% by weight of a release agent containing a silicone surfactant, and 0.1% by weight of a water-insoluble inorganic powder.
The present invention relates to an ink composition for a board marker containing 2 to 8% by weight.

[Structure and operation of the invention]

As described above, the binder in the ink composition of the present invention has a polymerization degree of 1. It is made of a water-soluble synthetic resin mainly composed of polyvinyl alcohol of less than ooo, but unlike the binder in ordinary writing instrument inks and paints, it is not used for the purpose of forming an ink film or adhering to the writing surface, but only for the erasability of the ink. It is used to improve the

In other words, in the formulation of the present invention, when the ink written on a writing surface such as a whiteboard dries, the polyvinyl alcohol described above causes the fine particles of the colorant in the ink to become coagulated and become coarse particles. On the other hand, it has poor adhesion to the writing surface, and the formed film is not very hard and has appropriate flexibility. Therefore, with water-based ink using this, after writing on the writing surface, when the handwriting is erased by wiping, the ink film tends to peel off from the writing surface.

In addition, the above-mentioned polyvinyl alcohol has a low surface tension and low viscosity in an aqueous solution, so it can improve the flow and writing properties of the ink with the permeable pen core made of fiber for board markers. Since the hygroscopicity of the film formed is relatively low, it has the advantage that handwriting is less likely to become sticky even under high humidity.

However, the degree of polymerization of this polyvinyl alcohol is 1.00
If it exceeds 0, the adhesiveness of the ink to the writing surface becomes excessive, the erasability of handwriting deteriorates, making it unsuitable for use as a board marker, and the viscosity of the ink increases, resulting in poor writing performance.

In addition, as this polyvinyl alcohol, a partially saponified type (approximately 86 to 89 mo1%) is particularly recommended,
In addition, the viscosity (20°C) of a 4% by weight aqueous solution is 3 to 1 Qcps.
It is preferable that the

As a suitable commercial product, for example, Gohsenol GL-03 manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd. GL-05, Poval PA-10゜PA-05 manufactured by Shin-Etsu Chemical Co., Ltd., Poval PVA-203, PVA-204 manufactured by Kuraray Co., Ltd.
Examples include the same PVA-205.

As the binder used in this invention, the above-mentioned polyvinyl alcohol may normally be used alone, but other water-soluble synthetic resins may be used in combination as a subcomponent if necessary.

The amount of the binder used may be relatively small because the function required of the binder in the present invention is to bind the fine particles of the colorant to each other to form coarse particles as described above.
As mentioned above, the amount is in the range of 2 to 10% by weight, particularly preferably 2 to 6% by weight, based on the total amount of the ink composition. If the amount used exceeds 10% by weight, the erasability of handwriting will deteriorate and the ink will thicken, resulting in poor writing performance;
If it is less than that, the above effect will be insufficient.

Natural adhesives include glue, gelatin, dextrin, etc., but inks using these agents are prone to rot and mold, and have the disadvantage of blocking colorants at high temperatures, so they are not suitable for board markers. It is unsuitable for ink.

The release agent used in this invention contains a silicone surfactant as described above, and the surfactant penetrates between the pigment particles and helps form a colored film when the written ink dries and is effective during erasing. It has the effect of making the peeling of the film extremely easy and reliable, and also has a superior surfactant effect compared to ordinary hydrocarbon-based surfactants. While it improves ``glue'' to surfaces, it also has an antistatic effect.

Various types of silicone surfactants can be used as the above silicone surfactant, but a copolymer in which the hydrophobic part is made of a silicone component and the hydrophilic part is made of a polyether component is preferred, and in particular, a copolymer made of dimethylpolysiloxane is preferred. A graft copolymer in which a polyether is bonded as a side chain to a linear chain is most suitable.

Such copolymers include the following:
1 is an alkylene group, R2 is an alkyl group or a hydrogen atom,
(m and n are integers of 1 or more, a and b are integers of 0 or more, and at least one of them is 1 or more) Furthermore, among the copolymers of the above formula, especially those with an average molecular weight of 1
,000 to about 12,000, degree of polymerization (number of Si atoms) 2
It is preferable that the weight ratio of the silicone component/polyether component is about 70/30 to 40/60, and the viscosity (at 25 DEG C.) is about 40 to 600 cst.

Suitable commercial products of such copolymers include, for example, L-7600, L-7604, and L-7600 manufactured by Nippon Unicar Co., Ltd.
-7607, TSF-4440 manufactured by Toshiba Silicone Corporation,
YSA-6403, KF-35 manufactured by Shin-Etsu Silicone Co., Ltd.
1, KF-353, KF-354. Same KF-355
etc.

Further, in the present invention, the above-mentioned silicone surfactant may be used alone as a release agent, but a release agent component made of another non-volatile substance may also be used in combination. As such other release agent components, polyhydric alcohols and derivatives thereof and dimethylpolysiloxane are recommended, with the latter being particularly preferred.

The above-mentioned polyhydric alcohols and their derivatives intervene as a lubricating film at the interface between the coarse pigment particles generated when the written ink dries and the writing surface, thereby weakening the adhesion at the interface and weakening the adhesion during erasing. The ink film is made to slide from the writing surface to make it easier to peel off, and in addition to acting as a release agent, the formulation of the present invention has been found to have the effect of improving the stability of the ink over time.

Preferred specific examples of the polyhydric alcohol and its derivatives include ethylene glycol, diethylene glycol,
Triethylene glycol, hexylene glycol, polyethylene glycol phenyl ether, average molecular weight 60
Examples include water-soluble polyhydric alcohols such as polyethylene glycol having an average molecular weight of 0 or less, polypropylene glycol having an average molecular weight of 400 or less, and glycerin, and derivatives thereof.

In addition, dimethylpolysiloxane is used in the form of an emulsion, spreads on the marking surface to form a silicone molecular film, and exhibits the effect of increasing the contact angle of the coarse pigment particles with the marking surface due to its ↑Ω aqueous property. This facilitates stripping, and in addition to acting as a stripping agent, the formulation of this invention has been found to have the effect of improving the stability of ink over time, similar to the water-soluble polyhydric alcohol described above. It is being

As such a dimethylpolysiloxane emulsion, one with an active ingredient concentration of about 27 to 38% by weight is suitable, and the viscosity of the base oil (25°C) is L
A value of 0OOcst or less is recommended. Commercially available products include LE-45 and LE-48 manufactured by Nippon Unicar Co., Ltd.
, LE-450, LE-460, KM-722, KM-740 manufactured by Shin-Etsu Chemical Co., Ltd. Same KM-742. KM-780, KM-786. KM-787, TSM-630, TSM-'631 manufactured by Toshiba Silicone Co., Ltd.
．． Examples include TSM-632.

When a silicone surfactant and the other release agent components mentioned above are used together as a release agent, the ratio of use is preferably in the range of about i:o, s to 5 by weight of the former: PIT.
If the latter is too small, effects such as stability over time will be insufficient, while if it is too large, handwriting tends to become sticky.

In addition, the amount of release agent used is within the range of 5 to 18% by weight based on the total amount of ink; if it is less than this range, the erasability will be poor, and on the other hand, if it is too much, the viscosity of the ink will increase, making it difficult to write. There is a problem that the stability over time deteriorates as well.

Coloring agents include various water-soluble dyes such as triallylmethane dyes and azo dyes, various organic pigments such as insoluble azo pigments, phthalocyanine pigments, and threne pigments, carbon blanks, and various inorganic pigments such as titanium oxide. Any of these water-dispersed pigments, which are obtained by kneading and grinding pigments in an aqueous medium containing a dispersant, can be used, but water-soluble dyes and water-dispersed pigments are particularly preferred from the viewpoint of preventing color separation. . The blending amount of such a colorant is 0.1 to 8% by weight, particularly preferably 0.1 to 8% by weight based on the total amount of the ink composition in terms of solids.
It should be in the range of 2 to 5% by weight; if it is more than 8% by weight, there is a problem that the ink flow (writing properties) deteriorates due to increased viscosity and solid content, and 0.1% by weight.
If the amount is too small, the coloring will be insufficient.

The water-insoluble inorganic powder significantly improves the erasability of water-based ink under high humidity by blending it with the above-mentioned binder made of water-soluble synthetic resin, release agent containing silicone surfactant, and coloring agent. , also acts to speed up drying.

In other words, even water-based inks containing the above-mentioned binder, release agent, and coloring agent within the above specified ranges exhibit sufficient erasability and quick-drying properties under normal conditions, but under high humidity conditions such as rainy weather or the rainy season, handwriting becomes difficult to write. It becomes difficult to dry, and even once it dries, it absorbs moisture and becomes incompletely erased, and colorant powder from the eraser transfers to the erased traces, making them more likely to stain. However, when the above-mentioned fine powder is blended into this water-based ink, the R
It dries quickly even under high humidity conditions, and can be erased without leaving any traces by just wiping it lightly, making it fully compatible with the strict erasing characteristics required of recent board markers. Furthermore, the addition of the powder also provides the secondary effect of preventing ink from dripping from the application site when using the board marker.

As such water-insoluble inorganic powder, in general board marker ink in which an impregnating material made of long fibers such as polyethylene or polyester is loaded in the application container, B.
A fine powder having a specific surface measured by the ET method of about 50 to 300 r+(/g) and an average particle size of its secondary particles of about 10 to 40 mm is suitable.

There are various types of oxide powders as the above-mentioned fine powder, but powders mainly made of ultrafine silicon dioxide produced by a vapor phase method are particularly preferred, and among these, powders containing hydrophobic groups such as methyl groups on the particle surface are particularly preferable. A fine powder consisting of bonded hydrophobic silica alone, and a small amount of about 1 to 20% by weight of hydrophobic silica and/or ultrafine aluminum dioxide produced by a gas phase method are mixed with ordinary wood-loving silica. Mixed oxide fine powder is recommended. In addition, commercial products of fine powder consisting of the above-mentioned hydrophobic silica alone include Aerosil R-972, Aerosil R-974, and Aerosil RX-200 manufactured by Nippon Aerosil Co., Ltd., and Silica D-10 and Aerosil D- manufactured by Degussa Japan Co., Ltd. 17, HDK-Hl 5 and HDK-H20 manufactured by Wacker Chemicals East Asia Co., Ltd., and the like. In addition, as the above-mentioned mixed oxide fine powder, Aerosil MO manufactured by Nippon Aerosil Co., Ltd.
Examples include X-80 (SiO□ contains 1% by weight of AltO), MOX-170 (same as above), and C0K-84 (SiO□ contains 20% by weight of A1zO3).

In addition to the fine oxide powder mentioned above, ink for valve action type board markers also contains various oxide powders with relatively large particle sizes, and ordinary paint fillers such as precipitated barium sulfate powder and talc powder. Water-insoluble inorganic powders similar to those described above can also be used.

The amount of water-insoluble inorganic powder used is 0.2 of the total amount of ink.
If the amount is less than this range, the erasability will be poor, and if it is too much, the viscosity of the ink will increase and the writing property will be deteriorated. The optimum range of the amount used is about 0.5 to 5% by weight.

The ink composition of the present invention contains each of the above components using water as a dispersion medium, but various additives such as other surfactants and preservatives can be appropriately blended with these components as necessary. . For example, by blending a fluorine-based surfactant in an amount of about 0.1 to 1.0% by weight based on the total amount of the ink composition, the surface tension of the ink is reduced and uneven dispersion when handwriting dries is eliminated. This has the advantage that it is possible to prevent the lines from becoming tacky.

The ink composition for board markers according to the present invention is suitable for writing on whiteboards, electronic blackboards, and other ink-permeable smooth writing surfaces such as wax, metal, glass, plastic, and plastic laminated paper. That's fine.

Furthermore, since the ink composition of the present invention has low volatility, a board marker containing it can be rewritten for up to about 5 hours even if you forget to close the camp.

〔Example〕

Hereinafter, this invention will be specifically explained based on examples.

In addition, parts and % below refer to parts by weight and %, respectively.
Means weight %.

Example 1 Polyvinyl alcohol (Poval PA-05, degree of polymerization 5
00-6001 Partially saponified type, 4% aqueous solution viscosity 5.0
±1. Oc ps.

)...4.0 parts dimethylsiloxane-polyether copolymer (L-7600,
)...6.0 parts Hydrophobic silica fine powder (Aerosil R-972, mentioned above)...
・3.0 parts preservative (KM-101A manufactured by Hoechst Synthetic Co., Ltd.
)...0.2 parts water ・ ・ ・ 2
5.0 parts After thoroughly dispersing and mixing the above composition in a ball mill, a water-dispersible pigment (Lafutimin Color Scarlet FL-G manufactured by Dainichiseika Chemical Co., Ltd., solid content 20-25 %)
...7.4 parts 35% dimethylpolysiloxane emulsion water ・ ・ 3
7. 4 parts were added and sufficiently dispersed and mixed using a homomixer, and coarse particles were removed by filtration to obtain a red ink for board markers.

Example 2 TS as dimethylsiloxane-polyether copolymer
I-4.440 (supra), KM-740 as dimethylpolysiloxane emulsion (38% concentration, supra)
Same as Example 1, except that the same amount of each was used and 2.5 parts of silica-alumina mixed oxide fine powder (Aerosil MOX-170. mentioned above) was used in place of the hydrophobic silica fine powder. A red ink for board markers was obtained.

Example 3 A red ink for a board marker was obtained in the same manner as in Example 1, except that 2.6 parts of HDK-Hl5 (described above) was used as the hydrophobic silica fine powder.

Example 4 Polyvinyl alcohol (Gohsenol GL-031 polymerization degree 300-4001 partial comparison, viscosity of 4% aqueous solution 3.5 ± 0.5 cps, above)
...4.0 parts dimethylsiloxane-polyether copolymer (same as Example 1) ...5.2 parts hydrophobic silica fine powder (same as Example 1) ...1.0 part fluorine-based Surfactant (Surf 1:l:/S manufactured by Asahi Glass Co., Ltd.
-141) -...0.6 part preservative (same as Example 1)...0.2 part water
・ ・ ・ 30.0 parts After thoroughly dispersing and mixing the above composition in a ball mill, a water-dispersed pigment (Lafutimin Color Blank FL-I,
Solid content 30-40%, above)...6.0 parts Polypropylene glycol (Mitsui Polyol #400 manufactured by Mitsui Toatsu Co., Ltd. Average molecular weight 400)...7.0 parts Water ・ ・ ・ 47
．． 0 parts were added and sufficiently dispersed and mixed using a homomixer, and coarse particles were removed by filtration to obtain a black ink for board markers.

Example 5 Polyvinyl alcohol (same as Example 1)...4.0
Dimethylsiloxane-polyether copolymer (Example 1)
)...6.0 parts Silica-alumina mixed oxide fine powder (Aerosil C0K-84, mentioned above)
...2.0 parts preservative (same as Example 1)
・0.2 parts water ・
25.0 parts of the above composition was sufficiently dispersed and mixed in a ball mill, and then an azo dye (Red No. manufactured by Mihara Kako Co., Ltd.) was added to the dispersion.

1, Cl-No. 16255) -0.5 parts 35% concentration dimethylpolysiloxane emulsion (same as Example 1)...20.0 parts water
・ ・ ・ 44.3 parts were added and sufficiently dispersed and mixed using a homomixer, and coarse particles were removed by filtration to obtain a red ink for board markers.

Comparative Example 1 Example 1 except that hydrophobic silica fine powder was not used.
A red ink for board markers was obtained in the same manner as above.

Comparative Example 2 Example 3 except that hydrophobic silica fine powder was not used.
A red ink for board markers was obtained in the same manner as above.

Comparative Example 3 A red ink for a board marker was obtained in the same manner as in Example 4, except that the amount of hydrophobic silica fine powder used was 10 parts.

An appropriate amount of the inks of the above Examples and Comparative Examples were filled into a tube feeder equipped with a polyester fiber pen core at the tip and filled with polyethylene long fibers as an ink absorber inside to make a board marker. We used the ink pen to write on the surface of an ink-permeable writing board, and examined the erasability and stickiness of the handwriting under various conditions. The stability of each ink over time was also tested. These results are shown in the table below. The types of writing boards, test methods and evaluations for each item are as follows.

(Writing board) A...Aluminum hauro whiteboard (manufactured by Plus) B...Polyethylene terephthalate laminate electronic blackboard (Board Fax, manufactured by Plus) (erasability under normal conditions) 20 copies, 3°C, 60 After 5 minutes of writing under the condition of ±5% RH, the normal felt eraser attached to the above writing board.
Erasing pressure 50-100 g/ca, erasing speed approximately 60c
An erasing operation was performed using m/sec as a standard, and the traces of handwriting were observed and evaluated in the next step.

○... Completely erased without leaving any traces.

△: Slight traces were observed.

×... Traces were clearly recognized.

(Erasability under high humidity) 5 minutes after writing on 25 copies under the conditions of 3° C. and 90±5% RH, the erasing operation and evaluation were performed in the same manner as above.

(Repeated erasability under high humidity) Writing under conditions of 25 ± 3°C and 290 ± 5% RH and the above erasing operation were repeated four times a day, and stains due to ink staining on the writing surface were observed after - weeks. It was evaluated in the following three stages.

○: No stains are seen at all.

△: Slight stains.

×: Significant dirt.

〔Effect of the invention〕

According to this invention, it is highly safe water-based with no odor or toxicity problems, and has excellent erasability, so even under high humidity, handwriting can be wiped lightly with a blackboard eraser or cloth material, etc. without leaving any traces. To provide an ink for a board marker that can be erased and does not easily stain the writing surface even if erased repeatedly under high humidity. Further, a board marker using this ink has the advantage that it can be rewritten even after a long period of time has elapsed after forgetting to tighten the cap, and that ink does not drip when writing.

Procedural amendment (voluntary) 1. Display of incident 1988 Patent Application No. 13759 3. Person who makes corrections Relationship to the incident: Patent applicant Address: 5-5-12 Tsuruhashi, Ikuno-ku, Osaka City, voluntary correction 5. Subject of correction The “Detailed Description of the Invention” column of the specification.

6. Contents of the amendment (1) In page 5, line 10, the phrase "of coloring agents" is corrected to "of coloring agents, inorganic fine powders, etc."

(2) In the 1st and 2nd lines of page 6, the phrase ``Small...hardly occurs'' should be corrected to ``Small (makes it difficult for sticky handwriting to occur.'')

(3) On page 13, lines 13-14, the phrase "coloring agent powder" is corrected to "colored powder of destroyed paint film."

(4) "Example 3" on page 21, line 9 is corrected to "Example 2."

(5) On page 21, lines 13-14, "red ink" should be corrected to "black ink."

that's all

Claims (1)

[Claims] (1) Using water as a dispersion medium, 0.1 to 8% by weight in terms of solid content
coloring agent, binder 2 to 10 consisting of a water-soluble synthetic resin mainly composed of polyvinyl alcohol with a degree of polymerization of 1,000 or less
Weight % and release agent containing silicone surfactant 5 to 1
An ink composition for a board marker, comprising 8% by weight of water-insoluble inorganic powder and 0.2 to 8% by weight of a water-insoluble inorganic powder.