JPH10130563A - Aqueous ink for ball point pen - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject ink satisfying a cap off resistant performance and also capable of writing with maintaining a clear handwriting not having a penetration to the back of a paper by containing a coloring agent, a water soluble organic solvent containing a specific ratio of water and urea and a polysaccharide reducing a shearing viscosity. SOLUTION: This aqueous ink for a ball point pen contains (A) a coloring material, (B) a water soluble organic solvent containing 30-50wt.% water and 10-30wt.% urea in the solvent and (C) a polysaccharide reducing a shearing viscosity (preferably a succinoglycan). The ink preferably shows viscosities in EMD type rotaviscometer at 20 deg.C, 25-100mPa.s at 100r.p.m, 150-300mPa.s at 10r.p.m and 1,200-1,800mPa.s at 1r.p.m. And it is preferable to add a phosphoric acid ester-based lubricant to the ink for reasons such as for improving the lubricating property of the ink, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a water-based ink for ballpoint pens. More specifically, the present invention relates to a water-based ink for ball-point pens exhibiting shear thinning. More specifically, the present invention relates to a water-based ink for a ballpoint pen having shear-thinning viscosity, which satisfies cap-off resistance, has no penetrating of handwriting, and can write clear handwriting while maintaining a smooth writing feeling.

[0002]

2. Description of the Related Art Conventionally, there have been proposed several water-based ballpoint pens using a shear-thinning ink, which is reduced in viscosity by a shearing force due to the rotation of a ball during writing.
For example, U.S. Pat. No. 4,671,691 discloses an aqueous ink comprising a colorant, a shear-thinning polymeric material, a polar organic solvent, and at least 50% by weight of water as a main solvent of the polar organic solvent. A composition is disclosed.
U.S. Pat. No. 5,466,281 discloses that in this type of shear-thinning ink, the mixing ratio of water is specified to not more than 20%, and the cap-off resistance, that is, the state in which the cap is removed. Even if it is left for about 7 to 30 days, the writing property is maintained and the performance satisfying the practicality is provided. By the way, when the former is left in the air for a long time with the cap removed, the proportion of water in the solvent is large, so the water content in the ink present in the gap between the ball at the tip of the writing tip and the ball holding part is high. Since the amount of evaporation is large, the ink viscosity is increased or the ink is solidified. This may hinder the outflow of ink at the time of writing, may cause blurring of handwriting, or may make writing impossible, and it is difficult to satisfy the cap-off performance. On the other hand, the latter is intended to reduce the proportion of water in the solvent and to add a large amount of a moisturizing water-soluble organic solvent such as ethylene glycol to suppress the evaporation of the solvent. Depending on the type of the water-soluble organic solvent, there is a problem in that handwriting oozes or ink penetrates to the back side of the paper surface, that is, so-called strikethrough occurs.
Further, in a system in which a high molecular weight polysaccharide is applied as a shear-thinning agent, the colloidal dispersibility of the polysaccharide is insufficient due to a small amount of water, and the desired shear-thinning property is reduced. Viscosity cannot be sufficiently exhibited, which adversely affects ink outflow.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional shear-thinning inks, satisfies the cap-off resistance and maintains clear handwriting without penetrating the handwriting with a smooth writing feeling. To provide a writable shear-thinning water-based ink for ballpoint pens.

[0004]

SUMMARY OF THE INVENTION The present invention relates to an aqueous ink for a ballpoint pen, comprising a water-soluble organic solvent containing water and urea as a coloring agent and a solvent, and a shear-thinning polysaccharide, wherein water is contained in the solvent. A water-based ink for ballpoint pens containing 30 to 50% by weight and 10 to 30% by weight of urea is required.
Further, the shear-thinning polysaccharide is a succinoglycan, and the viscosity in an EMD-type rotational viscometer at 20 ° C. is 100 r. p. 25 to 100 mPa · s in m,
10r. p. m at 150-300 mPa · s, 1r.
p. It is required that m be 1200 to 1800 mPa · s, and further that a phosphate ester-based lubricant be blended.

The water-based ink for a ballpoint pen of the present invention contains water and urea as essential components as a solvent. The water is 30
To 50% by weight, preferably 35 to 50% by weight. If the content is less than 30% by weight, the ratio of the water-soluble organic solvent in the ink excluding urea increases, so that it is difficult to obtain desired handwriting, and the dispersion stability of the shear-thinning polysaccharide is reduced.
In particular, the colloidal dispersion stability of succinoglycan is deteriorated, and the shear thinning effect cannot be effectively exhibited.
On the other hand, if it exceeds 50% by weight, the desired cap-off resistance cannot be obtained.

The urea is 10 to 30% by weight in a solvent,
Preferably, it is used in the range of 15 to 30% by weight. If the content is less than 10% by weight, good cap-off resistance is not exhibited. If the content is more than 30% by weight, the handwriting becomes difficult to dry due to the moisture retention of urea. By blending urea in the above weight range into the ink, the cap-off resistance is improved and the blending amount of other water-soluble organic solvents can be reduced.

Further, the water-based ink for a ball-point pen of the present invention comprises:
At 20 ° C., the viscosity in an EMD type rotational viscometer is 100
r. p. m: 25 to 100 mPa · s, 10 r. p. m
150 to 300 mPa · s and 1 r. p. 12 in m
00 to 1800 mPa · s, more preferably 100 r.p.m. p. 40 to 70 mPa · s in m, 10
r. p. m to 180 to 260 mPa · s, 1r. p. m
Satisfies the viscosity characteristic of 1350 to 1700 mPa · s, effectively achieving both low viscosity effective for writing by rotation of the ball at the writing tip and high viscosity in normal state (stationary state). Express and satisfy writing performance.

The water-soluble organic solvents other than urea can be used alone or in combination of two or more. For example, ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine,
Monoethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2- Pyrrolidone, N-methyl-2-pyrrolidone and the like.

The above-mentioned shear-thinning polysaccharides include polysaccharides such as xanthan gum, carrageenan gum, welan gum, guar gum, locust bean gum and derivatives thereof, and hydroxyethylcellulose. / Pyruvic acid or a salt thereof / succinic acid or a salt thereof / acetic acid in a molar ratio of 5 to 8/1 to 2 / 0.5 to 2 / 0.5 to 2 / 0.5 to 1.
An average molecular weight of about 10 consisting of a basic unit composed of
From 10,000 to about 8 million organic acid-modified heteropolysaccharides are preferably used. The succinoglycan is composed of a heteropolysaccharide having a side chain composed of glucose and galactose in the above molar ratio as a skeleton, and pyruvate is ketal-bonded to carbons at positions 4 and 6 of a monosaccharide at a side chain terminal, One carboxyl group of acetic acid and succinic acid is in the form of an ester bond with a free hydroxyl group of a constituent monosaccharide, and the free carboxyl group of pyruvic acid and succinic acid may be in the form of a sodium, potassium or calcium salt. . These polysaccharides are used in an amount of 0.01 to 8% by weight, preferably 0.1 to 4% by weight in the ink composition.

As the phosphate ester lubricant used in the present invention, a phosphate ester of polyoxyethylene alkylaryl ether or a derivative thereof is suitably used. For example, Plysurf A212E, A217E, and A2
15C and A219B (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.). L. B is preferably used because phosphate ester-based lubricants having 14 or more are excellent in solubility,
It is possible to obtain a water-based ink for a ball-point pen, which improves the lubricity of the ink, provides good ink output, and enables smooth writing.

As the colorant used in the ink composition of the present invention, all dyes and pigments that can be dissolved or dispersed in an aqueous medium can be used, and specific examples thereof are shown below. As the dye, an acid dye, a basic dye, a direct dye, or the like can be used. Examples of acid dyes include Newcoccin (CI. 16255), Tartrazine (CI. 19140), Acid Blue Black 10
B (CI. 20470), Acid Red M-81
(CI. 27290), Guinea Green (CI. 4)
2085), Brilliant Blue FCF (CI.42)
090), Acid Violet 6B (CI.425)
35), Acid Blue PG (CI. 42655),
Soluble Blue (C.I. 42755), Naphthalene Green (C.I.44025), Eosin (C.I.4)
5380), Phloxine (CI. 45410), Erythrosin (CI. 45430), Nigrosine (C.I.
I. 50420), acid flavin (CI. 562)
05) etc. are used.

As the basic dye, chrysoidin (C.I.
I. 11270), methyl violet FN (CI.
42535), crystal violet (C.I.42)
555), malachite green (CI. 4200)
0), Victoria Blue FB (CI.44045),
Rhodamine B (CI. 45170), Acridine Orange NS (CI. 46005), Methylene Blue B
(C.I. 52015) and the like are used.

As direct dyes, Congo Red (CI. 22120) Direct Sky Blue 5B (CI. 24400) Violet BB (CI. 27905) Direct Deep Black EX (CI. 3023)
5) Kayalas Black G Conch (CI. 35225) Direct Fast Black G (CI. 35255) Phthalocyanine blue (CI. 74180) or the like is used.

Examples of the pigment include inorganic pigments such as carbon black and ultramarine blue, and organic pigments such as copper phthalocyanine blue and benzidine yellow, as well as water that is already finely and stably dispersed in an aqueous medium using a surfactant. Dispersed pigment products and the like are used. I. Pigment 15: 3B [Product name: S.I. S.
Blue GLL, pigment content 24%, manufactured by Sanyo Dyeing Co., Ltd.] C.I. I. Pigment Red 146 [Product name:
S. S. Pink FBL, pigment content 21.5%, manufactured by Sanyo Dyeing Co., Ltd.] C.I. I. Pigment Yellow 81 [Product name:
TC YellowFG, pigment content: about 30%, manufactured by Dainichi Seika Kogyo Co., Ltd.] I. Pigment Red 220/166 [product name: TC Red FG, pigment content: about 35%, manufactured by Dainichi Seika Kogyo Co., Ltd.] and the like. As the fluorescent pigment, a fluorescent pigment in the form of fine particles of a synthetic resin in which various fluorescent dyes are made into a solid solution in a resin matrix can be used. Other examples include pearl pigments, gold and silver metallic pigments, luminous pigments, white pigments such as titanium oxide used for correction pens, metal powders such as aluminum, thermochromic microcapsule pigments, fragrances and fragrance capsule pigments.

The colorants may be used alone or in admixture of two or more, and are used in an amount of 1 to 40% by weight, preferably 2 to 35% by weight in the ink composition.

Also, alkyd resins as water-soluble resins,
One or more of acrylic resin, styrene-maleic acid copolymer, cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol, dextrin and the like can be used for imparting sticking property to the paper surface and the like.
It is used in the range of 30 to 30% by weight.

In addition, pH adjusting agents such as inorganic salts such as sodium carbonate, sodium phosphate and sodium acetate, organic basic compounds such as water-soluble amine compounds, benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite , Saponin and other rust inhibitors, sodium carbonate, 1,2-benzthiazolin-3-one sodium salt, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3,5,6-tetrachloro Preservatives or fungicides such as -4- (methylsulfonyl) pyridine, nonionic surfactants, humectants such as sorbitol, mannitol, sucrose, glucose, reduced starch hydrolyzate, sodium pyrophosphate, and defoamers To improve ink penetration Fluorine-based surfactants and nonionic surfactants may be used.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The aqueous ink of the present invention is prepared by adding a colorant and a water-soluble organic solvent to an aqueous paste obtained by dissolving a shear-thinning polysaccharide in water in advance, and heating as necessary. It is prepared by stirring and dissolving the components.

According to the above ink preparation method, inks of Examples and Comparative Examples were prepared, and a stainless steel tip holding a ball having a diameter of 0.4 mm was filled in a ballpoint pen refill fitted to one end of a polypropylene pipe. Thereafter, the ballpoint pen refill was incorporated into an exterior to obtain an aqueous ballpoint pen. The compositions of the aqueous inks for ballpoint pens of Examples and Comparative Examples are shown. In addition, the numerical value of the composition in a table | surface shows a weight part.

[Table 1]

[Table 2]

The contents of the raw materials in the table will be described along the note numbers. (1) Water black R510 [C. I. 542
0, manufactured by Orient Chemical Industry Co., Ltd.] (2) Eosin [C. I. 45380, manufactured by Daiwa Kasei Co., Ltd.) (3) Phloxine [C. I. 45410, manufactured by Eisen Co., Ltd.) (4) Acid Blue PG [C. I. 42655, manufactured by Sumitomo Mikuni Co., Ltd.) (5) Belson Crystal 120 (trade name of Daiwa Kasei Co., Ltd.) (6) Plysurf M208B (trade name of Daiichi Kogyo Seiyaku Co., Ltd.)

The following tests were performed using the aqueous ballpoint pens of Examples 1 to 7 and Comparative Examples 1 to 8. (1) Cap-off resistance test Using five water-based ballpoint pens, the cap was removed, placed horizontally at room temperature (20 ° C. to 27 ° C.) and humidity of 55 to 75% RH, and left for 10 days. I wrote on paper and examined how many blank writings were required before I could write (ink bleeds from the tip of the writing). (2) Writing feeling Five water-based ballpoint pens were written on paper, and the writing feeling was examined. (3) Bleeding of Handwriting The degree of bleeding of handwriting on the paper surface on which the writing feeling was examined was visually examined. (4) Penetration of Handwriting The degree of the strikethrough of the ink on the back side of the paper surface on which the writing feeling was examined was visually examined. (5) Dryness of handwriting Using five water-based ballpoint pens, writing was performed on paper, and after leaving it for 10 seconds, the handwriting was touched to check whether the handwriting was dry.

The test results are shown in the table.

[Table 3]

[Table 4] The contents of the test result evaluation symbols are as follows. (1) Cap-off resistance ◎: Immediate writing possible ○: Writable within 1 line (continuous circle about 15 cm, the same applies hereinafter) △: Writable within 1 to 3 lines ×: Until writing is possible (3) Writing feeling ：: Smooth writing is possible. Δ: Lack of smoothness, but at a level where writing is possible. ×: Not smooth, with a rough brush feel. (3) Blurring of handwriting ○: Handwriting does not blur. Δ: slight bleeding X: bleeding is severe. (4) Penetration of handwriting ○: Handwriting is not visible from the back side of the paper. Δ: Handwriting is slightly observed from the back side of the paper. ×: Handwriting is read from the back side of the paper. (5) Dryness of handwriting ：: Handwriting is dry, and the paper surface is not stained even when touched with a finger. Δ: The paper surface is slightly stained when touched with a finger. X: The paper surface becomes dirty when touched.

[0023]

According to the water-based ink for a ballpoint pen of the present invention, by specifying the weight of water and urea in a solvent, the cap-off resistance is improved, and the written characters are blurred.
The ink does not penetrate to the back side of the paper surface, the desired shear thinning function can be sustained and effectively developed, the appropriate amount of ink can be discharged, and a phosphate ester lubricant is added In such a system, the lubricity of the ink can be improved, a more uniform ink flow rate can be given, and a smooth writing feeling can be given.

Claims (4)

[Claims] 1. An aqueous ink for a ballpoint pen comprising a water-soluble organic solvent containing water and urea as a coloring agent and a solvent, and a shear-thinning polysaccharide, wherein 30 to 50% by weight of water and urea are contained in the solvent. An aqueous ink for a ballpoint pen, comprising 10 to 30% by weight. 2. The water-based ink for a ball-point pen according to claim 1, wherein the shear-thinning polysaccharide is a succinoglycan. 3. The water-based ink for a ball-point pen has a temperature of 20 ° C.
At a viscosity of 100 r.m. p.
m: 25 to 100 mPa · s, 10 r. p. 150 at m
~ 300 mPa · s, 1r. p. 1200 to 180 in m
The water-based ink for ball-point pens according to claim 1 or 2, which has a pressure of 0 mPa · s. 4. The water-based ink for ball-point pens according to claim 1, further comprising a phosphate ester-based lubricant.