JPH08311148A - Ink modifier for water-based ball-point ink - Google Patents

Abstract

PURPOSE: To obtain an ink modifier, comprising a specific water-soluble polyurethane compound and excellent in prevention of tip leakage of the ink and sedimentation of a colorant (shelf life) without deteriorating discharging properties of the ink. CONSTITUTION: This ink modifier comprises (C) a water-soluble polyurethane compound, derived by reacting (A) a water-soluble polyoxyalkylene polyol (preferably an ethylene oxide homopolymer and/or a random or a block copolymer of ethylene oxide and propylene oxide, e.g. polyethylene glycol) with (B) an organic polyisocyanate (preferably at least one selected from the group consisting of 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate) and having at least 60wt.% content of a polyoxyethylene unit.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an ink modifier for water-based ballpoint pens.

[0002]

2. Description of the Related Art Water-based ballpoint pens have solved the drawbacks of oil-based ballpoint pens, such as line cracking and fatigue during long-time writing. That is, the ink for water-based ballpoint pens has a low viscosity and thus has a light writing feel and a strong writing line. Besides that, light resistance,
It has become popular because of its features such as excellent water resistance. However, the low viscosity of the water-based ballpoint pen also causes ink leakage from the pen tip and sedimentation of the colorant. In order to solve this problem, a method of adding a gel-forming polymer substance such as polyvinyl alcohol or carrageenan as a modifier is known.

[0003]

However, even if a polymer substance is added so that the viscosity does not impair the writability, ink leakage from the pen tip and sedimentation of the colorant cannot be completely prevented. Also, although increasing the added amount can prevent ink leakage from the pen tip and sedimentation of the colorant,
There is a problem that the dischargeability of ink is reduced. .

[0004]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors solved the conventional drawbacks by using a specific water-soluble polyurethane compound as an ink modifier for an aqueous ballpoint pen. The present invention has been accomplished by finding that an aqueous ballpoint pen ink composition which can be obtained is obtained. That is, the present invention provides a water-soluble polyurethane compound (C) having a oxyethylene unit content of at least 60% by weight, which is derived by reacting a water-soluble polyoxyalkylene polyol (A) with an organic polyisocyanate (B). It is an ink modifier for water-based ballpoint pens.

In the present invention, as the water-soluble polyoxyalkylene compound (A), for example, ethylene oxide (hereinafter abbreviated as EO) homopolymer; EO / propylene oxide (hereinafter abbreviated as PO) copolymer; hydroxyl group Compound (a) having EO alone or EO and other alkylene oxide [PO, 1,2-butylene oxide, tetrahydrofuran, α-olefin oxide, alkylene oxide substitution product (epichlorohydrin, styrene oxide, etc.)] And a compound obtained by co-adding; and a mixture of two or more thereof.

Examples of the above (a) include polyhydric alcohols (ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, polypropylene glycol, polytetramethylene ether glycol, polybutadiene glycol, polycaprolactone polyol, dimethylolpropionic acid ( Salt), glycerin, trimethylolpropane, trimethylolethane,
Pentaerythritol, sorbitol, sucrose, etc.);
Polyhydric phenols (hydroquinone, catechol, etc.);
Bisphenols (bisphenol A, bisphenol S, tetramethylbisphenol A, tetramethylbisphenol S, etc.); water; and a mixture of two or more thereof. Of these, preferred are ethylene glycol, propylene glycol and water.

The addition mode when other alkylene oxides are used together with EO may be random addition or block addition, but the terminal portion of the polyoxyalkylene chain constituting (A) has a point of reactivity with organic polyisocyanate. Therefore, those having a hydroxyethyl group are preferable. The average oxyethylene unit content in (A) when EO and an alkylene oxide other than EO are used in combination is
It is usually 65% by weight or more, preferably 70% by weight or more.

Particularly preferable ones exemplified above as (A) are polyethylene glycol and EO /
It is a PO copolymer.

The number average molecular weight of (A) is usually 1,000 to
It is 30,000, preferably 2,000 to 25,000. When the number average molecular weight of (A) is less than 1,000, the content of polyisocyanate residues increases, and the polyurethane compound becomes poorly soluble in water, and when it exceeds 30,000, the reactivity with the organic polyisocyanate (B) is poor. It becomes difficult to obtain the polyurethane compound (C) having the desired performance.

In addition to the above (A) as a polyol component constituting (C), a compound having another hydroxyl group (provided that water is excluded, if necessary) within a range that does not impair the water solubility of (C). ) Can be used together. Examples of the other compound having a hydroxyl group include the above (a)
A compound having a hydroxyl group exemplified as (however,
Excluding water. ). The amount of the compound used is usually 10% by weight or less based on (A).

As the organic polyisocyanate (B),
For example, 4,4′-diphenylmethane diisocyanate (MDI), 2,4- or 2,6-tolylene diisocyanate (TDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPD)
I), ethylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-
Diisocyanates such as phenylene diisocyanate and xylylene diisocyanate; reaction products of tolylene diisocyanate and trimethylolpropane; polyphenylmethane polyisocyanates obtained by phosgenating polyamines obtained by reacting aniline with formaldehyde in the presence of hydrochloric acid; Mention may be made of crude polyisocyanates obtained in these production steps; and mixtures of two or more thereof. Among these, preferred are diisocyanates and crude diphenylmethane diisocyanate, and particularly preferred are MDI, TDI and I.
PDI and HDI.

In the present invention, the hydroxyl group of (A) and (B)
The equivalent ratio of the isocyanate group (hereinafter referred to as NCO group) is usually 1: (0.8 to 1.0), preferably 1:
(0.9 to 0.98). If the NCO group is less than 0.8 equivalent, the molecular weight of (C) becomes low, and sufficient viscosity cannot be obtained, causing sagging, and if it exceeds 1.0 equivalent, the residual NCO group reacts with water to cause water solubility. It is not preferable because it decreases.

The weight average molecular weight of the water-soluble polyurethane compound (C) in the present invention is usually 20,000 to 50.
30,000, preferably 30,000 to 400,000
Is. If the weight average molecular weight is less than 20,000, it is impossible to completely prevent ink leakage from the pen tip.
If it exceeds 000, the dischargeability of the ink is deteriorated.

The content of oxyethylene units in (C) is usually 60% by weight or more, preferably 80% by weight or more. If the content of oxyethylene units in (C) is less than 60% by weight, the water solubility will be insufficient.

The method for producing (C) is not particularly limited, and it can be obtained by reacting (A) with an organic polyisocyanate by a usual method for producing a polyurethane resin (one-shot method or multistage method). The reaction temperature for urethanization is usually 30 to 200 ° C, preferably 50 to 180 ° C.
The reaction time is usually 0.1 to 30 hours, preferably 0.1 to
8 hours. The urethanization reaction is usually carried out in a solventless system, but if necessary, it may be carried out in an organic solvent inert to isocyanate. Examples of the organic solvent include acetone, tetrahydrofuran, dimethylformamide, dimethyl sulfoxide, toluene, dioxane and the like. When a solvent is used, the solvent is usually distilled off after the reaction to obtain the water-soluble polyurethane resin (C).

The aqueous ball-point pen ink using the modifier of the present invention comprises the modifier, a colorant such as pigment and / or dye, a water-soluble organic solvent and water. In addition, known additives such as a surfactant, an antiseptic, an anticorrosive, and a dispersion stabilizer may be added if necessary. The amount of the modifier of the present invention to be added is usually 0.5 to 15 parts, preferably 3 to 12 parts with respect to 100 parts by weight of the ink (hereinafter, the parts are simply referred to as "parts"). If it is less than 0.5 parts, ink leakage from the pen tip cannot be sufficiently prevented, and if it exceeds 15 parts, the ink ejection property is deteriorated. Colorant amount is usually 5-10
Parts, the amount of water-soluble organic solvent is usually 10 to 30 parts, and additives such as surfactants, preservatives, rust preventives and dispersion stabilizers are usually 0.
It is from 05 to 10 parts. Examples of the colorant include organic pigments such as azo pigments, condensed polyazo pigments, phthalocyanine pigments, quinacridone pigments, indigo pigments, and thioindigo pigments, inorganic pigments such as carbon black, barium yellow, navy blue, and Bengal, and C.I. I. Acid Red 52, C.I.
I. Acid Blue 1, C.I. I. Acid dyes such as Acid Black 2, C.I. I. Direct Black 19, C.I.
I. Direct dyes such as Direct Blue 86, C.I. I. Basic Blue 7, C.I. I. Basic dyes such as Basic Red 1 are listed. Examples of water-soluble organic solvents include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, thiodiethylene glycol, propylene glycol, 1,3-butylene glycol, glycols such as glycerin, cellosolves such as ethylene glycol monomethyl ether, and diethylene glycol monomethyl ether. Carbitols, 2-pyrrolidone and the like.

The ink modifier of the present invention is used, for example, as follows. A colorant is added to a mixed solution containing the ink modifier of the present invention, a water-soluble organic solvent, water and, if necessary, other additives, and the mixture is stirred to obtain an aqueous ballpoint pen ink. In this case, the mixed solution is preferably stirred by a high speed stirrer having a high shearing force.

[0018]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. In the following, "part" means part by weight and "%" means% by weight.

Example 1 Polyethylene glycol (number average molecular weight 8,000) 1
00 parts and 2.05 parts of HDI were reacted at 170 ° C. for 5 hours to obtain a modifier [1] of the present invention composed of a water-soluble polyurethane resin. The weight average molecular weight by gel permeation chromatography (1) according to the above [1] is 8
It was 5,000.

Example 2 Polyethylene glycol (number average molecular weight 20,000)
100 parts, polyethylene glycol (number average molecular weight 8,
000) 100 parts, propylene glycol 2 parts and M
DI 8.7 parts was reacted at 180 ° C. for 3 hours to obtain the modifier [2] of the present invention composed of a water-soluble polyurethane resin. The weight average molecular weight of the [2] was 72,000.

Example 3 Polyethylene glycol (number average molecular weight 20,000)
90 parts, polyoxyethylene oxypropylene glycol [polypropylene glycol (number average molecular weight 3,50
0) with EO added; number average molecular weight 15,000
0] 10 parts, 3 parts of polytetramethylene ether glycol (number average molecular weight 1,000) and 1.4 parts of TDI are reacted at 160 ° C. for 5 hours to give the modifier [3] of the present invention comprising a water-soluble polyurethane resin. Obtained. The weight average molecular weight of the [3] was 89,000.

Example 4 Polyoxyethylene oxypropylene glycol [Polypropylene glycol (number average molecular weight 1,700) E
O added; 100 parts of number average molecular weight 8,500] and 2.5 parts of IPDI are reacted at 170 ° C. for 5 hours,
The modifier of the present invention comprising a water-soluble polyurethane resin [4]
I got The weight average molecular weight of the [4] was 69,000.

Example 5 200 parts of polyoxyalkylene polyol [hexylene glycol with random addition of EO and PO; number average molecular weight 15,000, EO = 75% by weight] and TD
2.2 parts of I was reacted at 150 ° C. for 8 hours to obtain a modifier [5] of the present invention composed of a water-soluble polyurethane resin. The weight average molecular weight of the [5] was 75,000.

Example 6 Polyoxyalkylene polyol [Glycerin with EO and PO randomly added; number average molecular weight of 30,000]
0, EO content = 80%] and 200 parts of MDI (1.7 parts) were reacted at 150 ° C. for 8 hours to obtain a modifier [6] of the present invention composed of a water-soluble polyurethane resin. The weight average molecular weight of the [6] was 62,000.

Performance Test Example 1 The modifiers [1] to [6] obtained in Examples 1 to 6 and carrageenan (Toyo Rayon product) as a comparative example, polyvinyl alcohol (“Gohsenol NH-17Q”; Nippon Synthetic Chemistry) 5% each, carbon black 8%, diethylene glycol monoethyl ether 20%, diethylene glycol monobutyl ether 5% and water 62%
To obtain a water-based ink. The diameter of each ink is 0.7 mm using a super hard ball.
Fill 5mm sheep white chips into a product and observe the ink leakage and storability according to the following test method.
The dischargeability of the ink was measured. The results are shown in Table 1.

(Test method) Pre-leakage of ink: The tip of the metal chip was faced downward in a temperature control room at room temperature of 23 ° C. and a humidity of 50% and left for a day and night. ○ indicates no ink leakage from the tip, Δ indicates slight leakage, leakage. There was an X. Storability: The colorant was allowed to stand for 3 months under the conditions of a temperature of 40 ° C. and a humidity of 60% and the sedimentation of the colorant was observed. No sedimentation was evaluated as ◯, small sedimentation was evaluated as Δ, and large sedimentation was evaluated as x. Ink dischargeability: The ink discharge amount when 100 m was written under the conditions of a writing speed of 400 cm / min, a writing angle of 70 °, and a writing load of 100 g, and 100 to 150 mg was ◯, 50 to 100 mg and 150 to 200 mg was Δ,
Those less than 50 mg and more than 200 mg were rated as x.

[0027]

[Table 1]

[0028]

INDUSTRIAL APPLICABILITY The ink for a water-based ballpoint pen using the modifier of the present invention prevents the ink from leaking out and settling the colorant without impairing the ejection property of the ink, as compared with the ink using the conventional modifier. It is extremely superior in terms of prevention (storability).

Claims (3)

[Claims] 1. A water-soluble polyurethane compound (C) derived from a reaction of a water-soluble polyoxyalkylene polyol (A) and an organic polyisocyanate (B) and having an oxyethylene unit content of at least 60% by weight. An ink modifier for water-based ballpoint pens. 2. The modifier according to claim 1, wherein (A) is an ethylene oxide homopolymer and / or a random or block copolymer of ethylene oxide and propylene oxide. 3. The modifier according to claim 1, wherein (B) is at least one selected from the group consisting of 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, isophorone diisocyanate and hexamethylene diisocyanate. .