JPH11148040A - Water base ink composition for ball-point pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject composition capable of supplying a right amount of the ink necessary for writing and having excellent time preservability and excellent writing touch by including a coloring agent, water and a specific thickener. SOLUTION: The ink composition comprises (A) a coloring agent [a dye (for example, C.I. ACID BLUE 90 or the like) and/or a pigment (for example, black iron oxide), (B) water (purified water), and (C) two or more kinds of thickeners selected from the group consisting of (i) a thickening polysaccharide (for example, xanthane gum), (ii) a clay thickener (for example, bentonite), and (iii) a polyacrylic acid-based thickener (for example, polyacrylic acid). The components A and B are preferably contained in amounts of 0.01-30 wt.% and >=5 wt.%, respectively, in the composition. The components Ci, Cii, and Ciii are preferably contained in amounts of 0.01-0.5 wt.%, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ballpoint pen ink composition for directly storing ink in an ink storage tube. The present invention relates to an excellent water-based ink composition for ballpoint pens.

[0002]

2. Description of the Related Art Conventionally, an aqueous ballpoint pen in which ink is directly accommodated in an ink container may be provided with plasticity or pseudoplasticity, for example, by imparting thixotropy to the ink. This has the effect of preventing blurring and line skipping due to excessive supply of ink or insufficient supply of ink during writing, as well as suppressing bleeding of the written lines. It also has the effect of suppressing.

The most effective example of imparting plasticity or pseudoplasticity to the ink based on the above technical idea is, for example, an aqueous ballpoint pen ink containing 0.20 to 0.45% by weight of xanthan gum. Composition (Japanese Patent Publication No. Sho 6)
4-8663) and xanthan gum in 0.1%.
20 to 0.45% by weight and 0.5 to 10.
An aqueous ballpoint pen ink composition characterized by containing 0% by weight (Japanese Patent Publication No. 1-16437). In these publications, pseudoplastic viscosity is imparted by including a specific amount of xanthan gum in the ink. As seen in the text of the above publications in experiments by the present inventors, 0.30 to 0.3. The content of 40% shows the most preferable pseudoplastic viscosity.

The most preferable pseudoplastic viscosity is defined by experiments conducted by the present inventors. The standard cone (1 °) of an E-type viscometer (ELD, EMD, EHD, etc.) manufactured by Toki Sangyo Co., Ltd.
34 ') / measured on a plate, in the range of 50 to 500 mPa · sec at 10 rotations (about 38 sec ^-1 ) and 1
10 rotations to 80 mPa · sec at 00 rotation (about 380 sec ^-1 )
Is in the range of

If the viscosity at 10 rotations is less than 50 mPa · sec, the ink is excessively supplied during writing, and the effect of suppressing the backflow of the ink during non-writing is small. 10
When the viscosity at the time of rotation exceeds 500 mPa · sec, an insufficient supply of ink occurs at the time of writing, and flaring and line skipping tend to occur. In particular, it is remarkable at a writing speed of 10 cm / sec (about writing a straight line using a ruler) or more. Viscosity at 100 rotations is 10
If it is less than mPa · sec, the ink may be excessively supplied during writing. However, if the setting of the viscosity at low rotation is appropriate, there is often no problem. When the viscosity at 100 revolutions exceeds 80 mPa · sec, the surplus ink accumulates on the pen tip, which drops and stains the paper surface, so-called “botte”.
The phenomenon of “dropping” occurs. These tests by the present inventors are completely consistent with the viscosity data described in JP-B 64-8673 and the like, and the numerical value of 0.20 to 0.45% as the added amount of xanthan gum is set appropriately. It can be said.

[0006] However, at present, water-based ballpoint pens filled with an ink containing xanthan gum often fail to write when stored at room temperature for six months to one year. A possible reason for this is that xanthan gum is an ionic polysaccharide and is described in Japanese Patent Publication No. 64-86.
No. 73 and Japanese Patent Publication No. 1-16437, 0.20 to 0.45% by weight of xanthan gum, or 0.7 to 6% by weight as described in U.S. Pat. No. 5,013,361. %, It reacts with the ionic material in the ink and adversely affects the storage stability of the pen over time.

That is, when a large amount of an ionic polysaccharide such as xanthan gum is used, for example, in the case of an ink system using a pigment as a colorant, the dispersion system of the pigment is destroyed, causing aggregation and sedimentation of the pigment. There is a problem that makes it impossible. Further, even in an ink using a dye as a coloring agent, since most water-soluble dyes are ionic, there is the same concern as the pigment such as precipitation and precipitation of crystals. Furthermore, in addition to the dispersants for dyes and pigments, ionic compounds such as rust inhibitors, fungicides, and lubricants are added to the aqueous ballpoint pen ink. These are selected from those that do not (and are difficult) to react with the dye in the process of developing a long aqueous ink, and are not guaranteed to hardly react with ionic polysaccharides such as xanthan gum. Therefore, it is necessary to select an ink material that does not easily react with ionic polysaccharides such as xanthan gum.However, it is very difficult to satisfy the performance required for ink such as writing quality, initial brushability, and line fastness. is there.

On the other hand, the present applicant has filed an application for an ink composition for an aqueous ballpoint pen in which the amount of ionic polysaccharide added is minimized and the viscosity is obtained by utilizing the synergistic effect with the nonionic polysaccharide. (Japanese Patent Application Laid-Open No. 6-256700), but because of the use of natural products having similar compositions, there are large variations among material lots, and there are many products that cause abnormal thickening and products that aggregate and separate. Can be seen. In addition, the nonionic thickening polysaccharide generally has a large amount of addition because of a smaller thickening effect than the ionic polysaccharide, and 0.5 to 3 weight% is required to obtain a preferable viscosity by adding alone. % Is usually used, but in this case, too, the production amount of the polysaccharide varies greatly. Therefore, as in the case of the ionic polysaccharide, the amount of addition must be minimized at present. Rather, the variation cannot be suppressed unless it is within 0.5% by weight, which has no effect alone.

Further, the polyacrylic acid-based thickener satisfies the above-defined viscosity conditions, and a good writing line may be obtained in some cases. It is a little difficult to prevent sedimentation of the pigment due to its small size, and at the same time, the leakage when the ballpoint pen cap is removed and the pen tip is left in contact with nothing without contact (hereinafter, this is defined as the term "DC") ) Is likely to occur. Inorganic fine particle thickeners such as fine particle silica have little effect in the presence of alcohols, which greatly restricts the design of the ink as a whole. Clay thickeners also tend to have a poor writing quality, and alone do not tend to fall into the viscosity range defined above.

As described in Japanese Patent Application Laid-Open No. 6-256700, if the amount of ionic polysaccharide is small, the adverse effect on ink can be minimized if the amount is small. % By weight.

On the other hand, ionic polysaccharides and nonionic polysaccharides can obtain large viscosities due to a unique synergistic effect. However, even in the case of other thickeners, there is no thickening due to the synergistic effect. A viscosity suitable for a ballpoint pen is obtained. In addition, even if the amount of the inorganic fine particle thickener is very small, the writing taste tends to be remarkably deteriorated.

As described above, ionic polysaccharides such as xanthan gum have the advantage of having a large thickening effect when added in a small amount, being easy to dissolve, and giving a suitable pseudoplasticity. It is very difficult to use as an ionic compound because of its poor nature. Also,
Nonionic polysaccharides must be diligent in controlling variability and cannot be used as a sole thickener in the manufacture of inks as industrial products. In addition, clay thickeners have a great effect of preventing the sedimentation of pigments due to the card house structure in water, which is the mechanism of thickening, but the above-mentioned ink viscosity is difficult to obtain and the tendency to impair writing taste. Therefore, it cannot be used alone.

Further, the polyacrylic acid-based thickener has less variation in the material lot and can obtain an ink that is stable over time. However, as described above, the sedimentation of a pigment having a high specific gravity or a large pigment of a particle system can be obtained. Since the deterrent effect is small and the direct current prevention effect is also small, the pigment used and the ink concentration are greatly restricted.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems and the like, and is intended to solve the problem. The present invention utilizes the thickening effect of a thickening polysaccharide and uses it alone. An aqueous ballpoint pen ink composition that solves the problems of clay thickeners and polyacrylic acid thickeners, supplies the necessary amount of ink needed for writing, and has excellent storage stability over time and excellent writing. The purpose is to provide.

[0015]

Means for Solving the Problems The present inventors have considered that the adverse effect on the writing taste of the clay thickener is smaller than that of the fine particle thickener. This is because, in the case of a fine particle thickener, an oxide of silicon, titanium or aluminum exists in the ink as it is. Although they are very hard and very fine particles, they become trapped between the ball at the tip of the ballpoint pen and the holder, impairing smoothness. In contrast, clay thickeners, especially smectites / permiculites, swell in water or organic solvents and exist in the ink in a soft form, so that they do not lose the smoothness of inorganic fine particles. That is, the fine particle thickener deteriorates the writing taste even with a small addition, whereas the clay thickener should have a range in which the addition of a small amount does not adversely affect the writing taste. The present inventors have, based on the above hypothesis, as a result of diligently searching for a range in which the mutual disadvantages of the polysaccharide thickener and the clay thickener or the polyacrylic acid-based thickener do not appear, as a result, the nonionic thickening polysaccharide If the content of ionic polysaccharides such as xanthan gum, clay thickener, and polyacrylic acid-based thickener is used in a specific range, the ink has an appropriate viscosity as an aqueous ballpoint pen ink that can directly store the ink in the ink storage tube. It has been found that an intended water-based ink for ballpoint pens can be obtained which does not exhibit both disadvantages. Furthermore, since the thickening mechanism of the clay thickener becomes a steric hindrance effective in suppressing the sedimentation of the pigment, when used in combination with a polyacrylic acid-based thickener, the advantages of both appear and the ink is suitable for aqueous ballpoint pens. By supplementing with a small amount of a thickening polysaccharide, it was found that suppression of sedimentation of the pigment of the ink using the polyacrylic acid-based thickener and improvement of the DC performance were found, and the present invention was completed. It was reached.

That is, the aqueous ink composition for a ballpoint pen according to the present invention includes the following (1) to (3). (1) It contains at least a colorant and water, and contains two or more types of thickeners selected from the group of thickener polysaccharides, clay thickeners, and polyacrylic acid thickeners. Aqueous ballpoint pen ink composition. (2) 0.01% to 0.5% by weight of a thickening polysaccharide;
The above-mentioned containing two or more kinds of thickeners selected from the group consisting of 01 wt% to 0.5 wt% clay thickener and 0.01 wt% to 0.5 wt% polyacrylic acid thickener. The ink composition for an aqueous ballpoint pen according to (1). (3) The thickening polysaccharide is an ionic polysaccharide represented by xanthan gum, welan gum and the like, and the content thereof is not more than 0.2% by weight based on the total amount of the ink composition (1) or (2). A) An ink composition for an aqueous ballpoint pen according to the above).

[0017]

Embodiments of the present invention will be described below in detail. The ink composition for an aqueous ballpoint pen of the present invention contains at least a colorant and water, and at least two types of thickeners selected from the group consisting of thickener polysaccharides, clay thickeners, and polyacrylic acid thickeners. It is characterized by containing an agent.

The thickening polysaccharides used in the present invention include, for example, ionic polysaccharides and nonionic polysaccharides. As ionic polysaccharides,
For example, at least one selected from ionic heteropolysaccharides represented by xanthan gum, welan gum, pectin, lanzan gum, leozan, etc. (one or more, the same applies hereinafter). Examples of the nonionic polysaccharide include, for example, at least one kind (one or more kinds, hereinafter the same) selected from guar gum, guar gum derivatives, locust bean gum and the like. As preferred thickening polysaccharides, ionic polysaccharides represented by xanthan gum, welan gum and the like are desirable in that high pseudoplasticity can be obtained with a small amount of addition.

Examples of the clay thickener used in the present invention include natural or synthetic clay thickeners. For example, at least one selected from smectite and permiculite represented by bentonite, montmorillonite, synthetic smectite and the like. No. Examples of the polyacrylic acid-based thickener used in the present invention include at least one of polyacrylic acid, sodium polyacrylate, and the like.

When each of the above-mentioned thickening polysaccharides, clay thickeners and polyacrylic acid-based thickeners are used alone in aqueous ballpoint pen inks, the outflow of the ink required for writing becomes poor. Or the storage stability with time is deteriorated, and the writing taste is poor. On the other hand, when a specific amount of two or more kinds of thickeners selected from the group of the thickening polysaccharides, clay thickeners and polyacrylic acid-based thickeners is used in the aqueous ballpoint pen ink, An object of the present invention is to solve the problem when used alone, and to obtain a water-based ink composition for a ball-point pen, which can exhibit the advantages of each of them in a synergistic manner. In the present invention, preferred embodiments of the two or more types of thickeners are combinations of at least one type selected from thickening polysaccharides and at least one type selected from clay thickeners, and selected from thickening polysaccharides. At least one
A combination of a type and at least one selected from polyacrylic acid-based thickeners, at least one selected from thickened polysaccharides, at least one selected from clay thickeners, and a polyacrylic acid-based thickened A combination with at least one selected from agents is desirable.

The content of the above-mentioned various thickening polysaccharides, clay thickeners and polyacrylic acid-based thickeners is preferably 0.01% by weight to 0.5% by weight with respect to the total amount of the ink composition. Is from 0.1% by weight to 0.5% by weight. If the content of each is less than 0.01% by weight, the effect of the addition is not exhibited, and the content of each is 0.5% by weight.
Exceeding the range is unfavorable because the writing quality is impaired, the ink viscosity exceeds the appropriate viscosity range, and the ink does not follow well when used as a ballpoint pen.

When ionic polysaccharides such as xanthan gum and welan gum are used as the thickening polysaccharide, the content thereof is 0.2% by weight or less based on the total amount of the ink composition. , Preferably 0.05% to 0.2% by weight. If the content of the ionic polysaccharide exceeds 0.2% by weight, it will react with other components in the ink and the like, resulting in poor storage stability over time, causing clogging by precipitates, Dispersion stability may be lost, resulting in poor writing.

Further, as described above, in the aqueous ballpoint pen ink composition of the present invention, even when an ionic polysaccharide or the like is used in the ink, the addition of the ionic polysaccharide or the like is minimized to prevent interference with other ink formulations. Since it has become possible to suppress the aging with no problem, all materials conventionally used for aqueous ballpoint pen inks can be used without any problem. That is, dyes and / or pigments can be used as the colorant used in the ink of the present invention. As a dye,
For example, C.I. I. ACID YELLOW 1, C.I.
I. ACID YELLOW 3, C.I. I. ACID
YELLOW 23, C.I. I. ACID YELLOW
36, C.I. I. ACID YELLOW 42, C.I.
I. ACID YELLOW 73, C.I. I. ACID
RED 27, C.I. I. ACID RED 18,
C. I. ACID RED 14, C.I. I. ACIDR
ED 13, C.I. I. ACID RED 26, C.I.
I. ACID RED 51, C.I. I. ACID RED
87, C.I. I. ACID RED 92, C.I. I. A
CID RED 94, C.I. I. ACID RED 5
2, C.I. I. ACID ORANGE 10, C.I. I.
ACID GREEN 16, C.I. I. ACID BL
UE 9, C.I. I. ACID BLUE 1, C.I. I.
ACID BLUE 74, C.I. I. ACID VIO
LET 49, FOOD RED 1, FOOD YE
LLOW 3, FOOD GREEN 3, FOODB
ROW 3, C.I. I. ACID BLACK 2,
C. I. Acidic dyes such as ACID BLUE 90;

Further, C.I. I. BASIC YELLOW
2, C.I. I. BASIC YELLOW 28, C.I.
I. BASIC YELLOW 36, C.I. I. BAS
ICRED 1, C.I. I. BASIC RED 18,
C. I. BASIC RED 36, C.I. I. BASI
C RED 37, C.I. I. BASIC VIOLET
1, C.I. I. BASIC VIOLET 3, C.I.
I. BASIC BLUE 1, C.I. I. BASIC
BLUE 3, C.I. I. BASIC BLUE5, C.I.
I. BASIC BLUE 7, C.I. I. BASIC
BLUE 9, C.I. I. BASIC BLUE 24,
C. I. BASIC BLUE 26, C.I. I. BAS
IC BLUE 45, C.I. I. BASIC BLUE
47, C.I. I. BASIC GREEN 1, C.I.
I. BASIC GREEN 4, C.I. I. BASIC
BLACK 2, C.I. I. BASIC BLACK
And 8 basic dyes. Further, C.I. I. DIR
ECT YELLOW 1, C.I. I. DIRECT Y
ELLOW 8, C.I. I. DIRECT YELLOW
26, C.I. I. DIRECT YELLOW 44,
C. I. DIRECT YELLOW 100, C.I.
I. DIRECT ORANGE 29, C.I. I. DI
RECT RED1, C.I. I. DIRECT RED
2, C.I. I. DIRECT RED 4, C.I. I. DI
RECT RED 13, C.I. I. DIRECT RE
D23, C.I. I. DIRECT RED 31, C.I.
I. DIRECT RED 75, C.I. I. DIREC
T RED 81, C.I. I. DIRECT BLUE
1, C.I. I. DIRECT BLUE 2, C.I. I. D
IRECT BLUE 6, C.I. I. DIRECT B
LUE 8, C.I. I. DIRECT BLUE 15,
C. I. DIRECT BLUE 86, C.I. I. DI
RECT BLUE168, C.I. I. DIRECT G
REEN 1, C.I. I. DIRECT GREEN
6, C.I. I. DIRECT GREEN 8, C.I. I.
DIRECTBROWN 1, C. I. DIRECT
BROWN 2, C.I. I. DIRECT BLACK
17, C.I. I. DIRECT BLACK 19, C.I.
I. DIRECT BLACK 22, C.I. I. DIR
ECT BLACK 118, C.I. I. DIRECT
And direct dyes such as BLACK 154.

Examples of the pigment include carbon black, titanium white, titanium black, zinc white, red iron oxide, chromium oxide, iron black, cobalt blue, alumina white, iron oxide yellow, viridian, zinc sulfide, lithopone, cadmium yellow, and vermilion. , Cadmium red, graphite, molybdenum orange, zinc chromate, strontium chromate, white carbon, clay, talc, ultramarine,
Inorganic pigments such as sedimentable barium sulfate, barite powder, calcium carbonate, lead white, navy blue, manganese violet, aluminum powder, brass powder and the like. I. PIGM
ENT YELLOW 34, C.I. I. PIGMENT
RED 104, C.I. I. PIGMENT BLUE
27, C.I. I. PIGMENT BLUE 17,
C. I. Pigment Red 81, C.I. I. PI
GMENT VIOLET 1, C.I. I. Pigmen
T BLUE 1, C.I. I. PIGMENT VIOL
ET3, C.I. I. Pigment Red 53, C.I.
I. Pigment Red 49, C.I. I. PIGME
NT RED 57, C.I. I. PIGMENT RED
48, C.I. I. PIGMENT YELLOW 3,
C. I. Pigment Yellow 1, C.I. I.
Pigment Yellow 74, C.I. I. PIG
MENT YELLOW 167, C.I. I. PIGME
NT YELLOW 12, C.I. I. PIGMENT
YELLOW 14, C.I. I. PIGMENT YEL
LOW 17, C.I. I. PIGMENT YELLOW
13, C.I. I. PIGMENT YELLOW 5
5, C.I. I. PIGMENT YELLOW 83,
C. I. PIGMENT ORANGE 16, C.I.
I. PIGMENT ORANGE 13, C.I. I. P
IGMENT ORANGE5, C.I. I. Pigmen
T RED 38, C.I. I. PIGMENT RED2
2, C.I. I. Pigment Red 5, C.I. I. P
IGMENT RED 146, C.I. I. Pigmen
T RED 245, C.I. I. PIGMENT VIO
LET 50, C.I. I. PIGMENT BLUE 1
5, C.I. I. PIGMENT GREEN 7, C.I.
I. Pigment Yellow 95, C.I. I. P
IGMENT YELLOW 166, C.I. I. PIG
MENTVIOLET 19, C.I. I. PIGMENT
And organic pigments such as VIOLET 23. The above various dyes and / or pigments can be used alone or in combination of two or more, and the content thereof is 0.01 to 30% by weight based on the total amount of the ink composition.

In order to dissolve the above-mentioned thickener polysaccharide or polyacrylic acid thickener, or to swell the viscosity thickener effectively, 5% by weight or more based on the total amount of the ink composition is used. Preferably, water (purified water) of 40% or more is required. Further, the moisturizing properties of ethylene glycol, diethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, thiodiglycol, glycerin, diglycerin, 2-pyrrolidone, n-methyl-2-pyrrolidone, dimethylformamide, dimethylimidazolidinone, etc. It is preferable to use one or more kinds of water-soluble organic solvents.

In addition, as required, ammonia, urea, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium carbonate and the like, alkali metal salts of carbonic acid and phosphoric acid, hydroxides of alkali metals such as sodium hydroxide, etc. PH adjuster, phenol, sodium omazine, sodium pentachlorophenol, 1,2-benzisothiazoline 3-one,
2,3,5,6-tetrachloro-4 (methylsulfonyl) pyridine, benzoic acid such as sodium benzoate, alkali metal salts of sorbic acid or dehydroacetic acid, preservatives or fungicides such as benzimidazole compounds, benzotriazole, Dicyclohexylammonium nitrite,
Rust inhibitors such as diisopropylammonium nitrite and tolyltriazole; polyoxyethylene and polyoxypropylene such as polyoxyethylene lauryl ether; and derivatives of polyoxyethylene or polyoxyethylene polyoxypropylene.
Derivatives of glycerin, diglycerin or polyglycerin such as tetraglyceryl distearate, sorbitan derivatives such as sorbitan monooleate, surfactants having a fluorinated alkyl group such as perfluoroalkyl phosphate, polyethylene glycol adducts of dimethyl polysiloxane, etc. And a lubricating and wetting agent such as polyether-modified silicone.

When an inorganic or organic pigment is used as a colorant, the surfactants exemplified as the lubricating and wetting agents also have a function as a dispersion stabilizer, but the alkylated sulfonic acid of the higher fatty acid amide is used. Salts, anionic surfactants such as alkyl allyl sulfonates, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylic acid, acrylic acid copolymer, acrylic methacrylic resin, styrene acrylic resin, maleic resin, styrene maleic acid It is preferable to use a water-soluble polymer such as a resin as a dispersant.

In the production of the ink of the present invention, no particular attention should be paid to the production method of other water-based ball-point pen inks. Absent. As an example of a simple method for producing the ink of the present invention, when a dye is used as a coloring agent, water, a humectant, a lubricant, and the like are dissolved at room temperature to form a thickening polysaccharide, a clay thickener, and a polyacryl. Two or more thickeners selected from acid thickeners are dissolved and dispersed until uniform. Thickeners may be combined after separately homogenizing.

Next, a dye and optional additives are added. In this case, it may be preferable to add the pH adjuster prior to the dye in some cases, but even at the same time or later, there is no effect on the performance of the resulting ink. Moreover, any order of blending does not affect the performance of the resulting ink. After the compounding agent is uniformly dissolved or dispersed, it is desirable to perform filtration. In the present invention, since it is assumed that the ballpoint pen is used for an aqueous ballpoint pen having a simple structure as shown in FIG. 1, if undissolved matter or dust is mixed in, it may be clogged around the pen tip ball. It is. Filtration is
Pressure filtration is considered to be the most efficient in terms of industrial production using ordinary filter paper, but there is no effect on ink performance under normal pressure or reduced pressure filtration. At the time of filtration, filtration can be performed more efficiently by using a filter aid such as celite.

When a pigment is used as a coloring agent, or when a dye and a pigment are used in combination, there are some restrictions on the preparation procedure. This is because the molecules of the polysaccharide or polyacrylic acid to be added may be cut by the shearing force applied when dispersing the pigment. In order to avoid this, for example, an ink is prepared by the following method. First, a liquid in which a humectant or a lubricant is dissolved in water (hereinafter referred to as a vehicle) contains a dispersant and a pigment, and, if necessary, one or more additives other than a thickening polysaccharide and a polyacrylic acid-based thickener. Add parts or all. At this point, if a clay thickener is added, the viscosity may increase and it may be difficult to handle. However, in order to disperse the clay more uniformly, the clay thickener should also be used with a dispersing machine. At this time, the vehicle is not used in the final desired blending amount, but in such a blending amount that the pigment can be dispersed most efficiently by the disperser used, such as a three-roll mill, a bead mill, or a kneader. Then, after uniformly dispersing with a disperser, the coarse particles of the pigment, undissolved matter and contaminated solid matter are removed by centrifugation or filtration, and the remaining water and additives are added, and the ionic polysaccharide is added. Stir until uniform to obtain ink. If it is difficult to handle the clay thickener when it is added first, the clay thickener is added simultaneously or in the same manner as the other thickeners. Finally one more
It is preferable to filter coarsely to remove coarse solids.

The water-based ink for a ballpoint pen of the present invention configured as described above can supply the ink required for writing without excess or shortage, and is excellent in storage stability over time and writing quality. That is, ionic xanthan gum, welan gum, etc., which provide an appropriate viscosity to the aqueous ballpoint pen ink that directly stores the ink in the ink storage tube, impart ideal viscoelasticity to the ink. In addition to the poor storage stability over time due to the reaction with the components in the ink, the use of clay thickeners, polyacrylic acid-based thickeners, etc. alone has unique disadvantages. Therefore, when the upper limits of the amounts used are determined and two or more types are used in combination, the dispersion is less than when each thickener is used alone, and an ideal viscosity is obtained, and the sedimentation property of the pigment is also improved. In addition, the stability over time is improved (these points will be described in more detail in Examples and the like described later).

[0033]

Next, the present invention will be described in detail with reference to examples and comparative examples, but the present invention is not limited to these examples. Hereinafter, the blending unit “parts by weight” is abbreviated as “parts”.

(Preparation of Black Ink Base 1) Water Black 187 (Black Dye; trade name of Orient Chemical Co., Ltd.) 7.0 parts Propylene glycol 30.0 parts Potassium oleate 0.5 parts Sodium omadine 0.1 parts Urea 1.0 part Water 41.4 parts The above mixture was stirred to prepare a black ink base 1.

(Preparation of Black Ink Base 2) PRINTEX 25 (Carbon Black: trade name of Tegusa Company) 7.0 parts Julimer AT-960P (styrene-acrylic resin: trade name of Nippon Pure Chemical Co., Ltd.) 3.5 parts Glycerin 20.0 parts Triethanolamine 0.3 parts Potassium ricinoleate 0.5 parts 1,2-Benzisothiazoline 3-one 0.1 parts Water 48.6 parts After kneading the above with a horizontal bead mill for 30 minutes, centrifugation To remove black particles to prepare a black ink base 2.

(Preparation of Black Ink Base 3) MCF-88 (carbon black: trade name of Mitsubishi Kasei Co., Ltd.) 7.0 parts SMA 1000 (styrene-maleic resin: trade name of ATOCHEM company) 3.0 parts diethylene glycol 10 0.0 parts Propylene glycol 15.0 parts Triethanolamine 0.3 parts Phosphanol RE510 (phosphate ester: trade name of Toho Chemical Co., Ltd.) 0.5 parts 1,2-benzisothiazoline 3-one 0.1 parts Water 44.1 parts The above was kneaded with a horizontal bead mill for 30 minutes, and then coarse particles were removed by centrifugation to prepare a black ink base 3.

(Preparation of Blue Ink Base 1) Blue No. 404 (legal dye: manufactured by Kishi Kasei Co., Ltd.) 7.0 parts Joncryl 62 (styrene acrylic acid 34% ammonia neutralized aqueous solution; Johnson Co., Ltd.) 7.0 parts Glycerin 30.0 parts Potassium oleate 0.5 parts Urea 1.0 parts 1,2-Benzisothiazoline 3-one 0.1 parts Water 34.4 parts After kneading the above with a horizontal bead mill for 30 minutes, Coarse particles were removed by centrifugation to prepare Blue Ink Base 1.

Example 1 Black ink base 1 80 parts KIA 96 (Welan gum; trade name of Sansei Co., Ltd.) 1% aqueous solution 10 parts SWN (synthetic smectite; Corp Chemical Co., Ltd.) 5% aqueous dispersion Example 1 was obtained by filtering the mixture of 10 parts or more after stirring.

(Example 2) Black ink base 2 80 parts Xanthan gum 1.5% aqueous solution 10 parts Junron PW-110 (polyacrylic acid; trade name of Nippon Pure Chemical Co., Ltd.) 2% aqueous solution 10 parts After stirring, the mixture was filtered to obtain Example 2.

(Example 3) Black ink base 3 80 parts Junron PW-110 (same as Example 2) 2% aqueous solution 10 parts SWF (synthetic smectite; trade name of Corp Chemical Co.) 1% aqueous dispersion 10 parts After stirring the above mixture, the mixture was filtered to obtain Example 3.

(Example 4) Blue ink base 1 80 parts Xanthan gum 1.5% aqueous solution 10 parts SWF (same as in Example 3) 4% aqueous dispersion 5 parts Rheogic 250H (sodium polyacrylate; Nippon Pure Chemical Co., Ltd.) ) Trade name: 5% 2% aqueous solution The above mixture was filtered after stirring, and Example 4 was obtained.

(Example 5) Black ink base 3 80 parts Junron PW-110 (same as Example 2) 0.2 parts SWF (same as Example 3) 0.1 parts Water 19.7 parts The above was treated with a homogenizer. After stirring, the mixture was filtered to obtain Example 5.

Example 6 Black ink base 3 80 parts SWF (same as Example 3) 0.1 part Water 9.9 parts After kneading the above with a horizontal bead mill for 5 minutes, Junron PW-110 (Example 2) 10% of a 2% aqueous solution was added, and the mixture was stirred and filtered, whereby Example 6 was obtained.

(Comparative Example 1) Black ink base 1 80 parts KIA96 (same as in Example 2) 1% aqueous solution 10 parts Guarcoal (guar gum; trade name of Sanseki Co., Ltd.) 5% aqueous solution 10 parts After filtration, Comparative Example 1 was obtained.

(Comparative Example 2) Black ink base 2 80 parts Xanthan gum 1.5% aqueous solution 20 parts The above composition was stirred and then filtered to obtain Comparative Example 2.

(Comparative Example 3) Black ink base 3 80 parts Carbopol 940 (alkali thickening type acrylic resin; trade name of BF Goodrich Co., Ltd.) 1% aqueous solution 20 parts Comparative Example 3 was obtained.

(Comparative Example 4) Black ink base 3 80 parts KIA96 (same as in Example 2) 2% aqueous solution 10 parts Aerosil # 380 (fine particle silica; trade name of Nippon Aerosil Co., Ltd.) 1% aqueous dispersion 10 parts or more After stirring, the mixture was filtered to obtain Comparative Example 4.

(Comparative Example 5) Blue ink base 3 80 parts SWF (same as in Example 2) 3% aqueous dispersion 20 parts

(Comparative Example 6) Blue ink base 1 80 parts Xanthan gum 1.5% aqueous solution 9 parts SWF (same as in Example 2) 5% aqueous dispersion 11 parts The above mixture was filtered after stirring, and Comparative Example 6 I got

The above six types of inks of Examples 1 to 6 and the inks of Comparative Examples 1 to 6 were prepared as prototypes, and subjected to physical properties tests such as viscosity, writability test, and direct current test by the following measuring methods. evaluated. The results are shown in Table 1 below.

Test 1 (Physical property test such as viscosity) The initial value of the ink viscosity was determined at 10 rotations (about 40
If the pen is filled in a range of 50 to 500 mPa · sec in c- ¹ ) and 80 mPa · sec or less at 100 rotations (about 400 sec ⁻¹ ), a good result may be obtained when the pen is filled. ○ ”, if one of them is out of order,“ x ”
It was determined. Further, the sample was sealed in a 50 ml sample tube and allowed to stand for 6 months, and the viscosity of the ink was measured. Those with a significant difference (more than ± 20%) compared to the initial viscosity,
Those which did not fall within the same viscosity range as the initial value were judged to be unfavorable, and were judged to be "x". A sample having a small change in viscosity and falling within the acceptable range of the initial value was judged as “○”. The viscosity was measured at 10 rpm and 100 rpm using an EMD viscometer and an EHD viscometer manufactured by Toki Sangyo Co., Ltd. In this test, if both items are not "O", the ink is judged to be unsuitable as an ink for an aqueous ballpoint pen.

Test 2 (Writing Test) Each of Examples 1 to 6 and Comparative Examples 1 to 6 was assembled into a ballpoint pen having the form shown in FIG. 1 and a sensory test was conducted by a monitor of 20 persons. 5 points for light, smooth and beautiful drawing lines, 4 points for 3 points that lack smoothness or lightness, or lines with varying thickness or cut off The score of 20 people was superior, with 1 score being heavy and lacking smoothness, broken lines or changing thickness, and 0 score being unable to draw. The best point is 100 points, but since there was no defect in the written inspection at the time of sample assembly, the lowest point was actually 20 points.

Test 3 (DC Test) The cap of the form shown in FIG. 1 was removed, and 20 samples of each sample suspended in the test tube with the pen point down and not touching anywhere were allowed to stand at room temperature for 1 week. Then, the amount of leaked ink was observed. 5 points where no ink has leaked from the tip of the chip, 4 points where the leaked ink is approximately the same size as the ball, 3 points where the volume of ink is about 3 times the size of the ball, about 1 mm in diameter Up to the hemisphere of 2
Point, one with more leakage on the pen tip
The points and those that leaked were regarded as 0 points, and the evaluation was made based on a total of 20 points. The higher the score, the better the result.

[0055]

[Table 1]

(Consideration of Table 1) As is apparent from the results of Table 1, the initial value of the viscosity of Test 1 was originally designed to fall within the range of all Examples 1 to 6 and Comparative Examples 1 to 6. However, Comparative Example 1 and Comparative Example 6 have deviated.
Comparative Example 1 is a combination of an ionic polysaccharide and a nonionic polysaccharide. Originally, good results are often obtained for all items, but the viscosity variation of guar gum alone,
Or, it may be a variation in compatibility with kiwelan gum (good results may be obtained depending on the material lot), or the viscosity may be excessively increased as in this case, resulting in a poor ink output and a ballpoint pen which is difficult to write. Comparative Example 6 is an example in which the use of a large amount of any clay thickener results in excessive thickening, impairing the function as a ballpoint pen ink.

Next, the viscosity measurement after 6 months shows that Comparative Example 2 was poor. This is probably because the xanthan gum in the ink has reacted with other ink components. According to the test by the present inventors, when xanthan gum is added in excess of 0.2% by weight, the viscosity tends to increase with time, and the alkali-thickened polyacrylic as in Comparative Example 3 is observed. There is a tendency for the system resin alone to decrease. The former believes that the xanthan gum reacts with the components in the ink to cause partial gelation. The latter is due to the effects of excretion and dead bodies of fungi present in trace amounts in the ink, and the decomposition of ethylene and propylene chains contained in additives and solvents into formic acid and glycolic acid.
This is because H decreases.

In the writing taste test of Test 2, Comparative Example 4 using the inorganic fine particle thickener and Comparative Example 5 using only the clay thickener gave poor results as described in the text. Also,
Comparative Examples 1 and 6 whose viscosities were not within the allowable range were also evaluated very poorly. Further, in the DC test of Test 3, the results obtained by thickening with the alkali thickening type acrylic resin of Comparative Example 3 showed bad results as described in the text, for example, 11 out of 20 ink drops were confirmed to fall. ing. Also,
Even though Aerosil 380, which is the class having the highest thickening effect, was used as the inorganic fine particle thickener, Comparative Example 4 in which the viscosity was increased with the inorganic fine particle thickener also showed relatively poor results.

On the other hand, Embodiment 3 and Embodiments 5 and 6
Is a difference in the blending procedure, but similar good results are obtained in any of the physical property test such as viscosity test, writing taste test, and direct current test. In Example 4 and Comparative Example 6, the blue ink was used, but no specific tendency was observed as compared with the black ink.
Further, when a test according to the present example was performed with other colors for reference, no specific tendency due to color difference was observed.

Comprehensively evaluating the results in Table 1 above, the inks of Examples 1 to 6 which fall within the scope of the present invention are selected from the group consisting of thickening polysaccharides, clay thickeners, and polyacrylic acid thickeners. 2
It is clear that a thickening effect can be exerted with a small amount of addition of more than one kind of thickener, and the degree of displacement is stable with time, and it is clear. As described above, it has been found that the aqueous ballpoint pen ink of the present invention is an excellent one that can stably maintain the thickening effect over time by using an ionic polysaccharide and a clay thickener.

[0061]

According to the present invention, there is provided an ink composition for a water-based ball-point pen which supplies an adequate amount of outflow of ink required for writing, and has excellent storage stability over time and writing quality.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an aqueous ballpoint pen using the ink follower of the present invention.

[Explanation of symbols]

 A water-based ballpoint pen 1 cap 2 rubber for pen tip sealing 3 pen tip 4 ball 5 joint between pen tip and ink storage tube 6 ballpoint pen shaft 7 ink storage tube 8 ink 9 ink follower 10 tail plug

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shigeru Miyazaki 2-5-1-12 Irie, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside Mitsubishi R & D Co., Ltd. Yokohama Research and Development Center (72) Inventor Miki Sugiyama, Kanagawa-ku, Yokohama-shi, Kanagawa 2-5-12 Irie Inside the Yokohama R & D Center, Mitsubishi Pencil Co., Ltd. (72) Katsuhiko Shiraishi 2-5-1-12 Irie, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Yokohama R & D Center, Mitsubishi Pencil Co., Ltd.

Claims (3)

[Claims] 1. A method comprising: containing at least a colorant and water; and containing two or more kinds of thickeners selected from the group consisting of thickener polysaccharides, clay thickeners, and polyacrylic acid thickeners. A water-based ink composition for a ballpoint pen. 2. 0.01% to 0.5% by weight of a thickening polysaccharide, 0.01% to 0.5% by weight of a clay thickener and 0.01% to 0.5% by weight. The water-based ink composition for a ball-point pen according to claim 1, comprising two or more kinds of thickeners selected from the group consisting of polyacrylic acid-based thickeners. 3. The thickening polysaccharide is an ionic polysaccharide represented by xanthan gum, welan gum and the like, and its content is 0.2% by weight or less based on the total amount of the ink composition. A water-based ink composition for a ballpoint pen according to the above.