JP2003138196A - Ink for ballpoint pen and ballpoint pen charged with the ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide ink which has good temporal stability, does not cause the leakage of the ink from the tip of a ballpoint pen, even when used in an ordinary single color ballpoint pen and in a composite/multicolor ballpoint pen at ordinary temperature and humidity and at high temperatures and high humidity, and can give smooth writing touches, and to provide a ballpoint pen using the ink. SOLUTION: Acrylic ultra fine particles are added to a ballpoint ink having a viscosity of 1,500 to 8,000 mPa.s at 25 deg.C and at a shear rate of 9.60 S<-1> .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink for a ballpoint pen and a ballpoint pen filled with the ink for the ballpoint pen. More specifically, it is suitable for use in a ballpoint pen having a structure having an ink containing tube of a small diameter. The present invention relates to a ballpoint pen ink that does not cause tip leakage and has a smooth writing taste, and a ballpoint pen filled with the ink for a ballpoint pen.

[0002]

2. Description of the Related Art Ballpoint pen inks are usually composed of colorants, resins, solvents, lubricants and the like. In general, the ink for ball-point pens has a very high viscosity of 10,000 to 20,000 mPa.s at a shear rate of 9.60 S ^-1, and therefore the ink from the tip of the ball-point pen tip under normal temperature and humidity conditions. Although there is almost no problem with the natural outflow of the so-called “blow-out phenomenon” (hereinafter referred to as “tip leakage”), there is a problem that the writing quality is heavy. Viscosity of 1,500 to 8,000 mPa.s to improve writing
If it is lowered to 1, a smooth writing feeling can be obtained, but since the viscosity decreases due to the moisture absorption of the ink after manufacturing, tip leakage easily occurs even at room temperature. In addition, in a compound / multicolor ballpoint pen that has many cores mounted on one shaft, the tip leakage is higher than that of a normal single color ballpoint pen under high temperature and high humidity conditions such as a chest pocket due to the mechanism. Easily occur.

Various methods have been proposed as methods for preventing tip leakage. For example, JP-A-9-078021 proposes a method of blending a crosslinked N-vinylacetamide polymer, which can impart pseudoplasticity to the ink and further impart appropriate viscoelasticity and spinnability. Have been described. However, since the cross-linked N-vinylacetamide polymer has high hygroscopicity and poor stability over time,
There is a problem that it is easy to cause phenomena such as bloating and crying, and it is difficult to obtain normal ballpoint pen performance for a long period of time.

Further, JP-A-7-196972 and JP-A-7-19727.
In JP-A-268368 and JP-A-9-302298, there is proposed a method of adding a fatty acid amide wax to impart shear thinning property to the ink to prevent tip leakage, but when added to an ink having a relatively low viscosity. Or composite /
When used in a multicolor ballpoint pen, it is difficult to prevent tip leakage even under normal temperature and humidity conditions. In addition, the wax-based non-Newtonian viscosity-imparting agent has a problem in that it is inferior in stability over time and it is difficult to obtain ordinary ballpoint pen performance for a long period of time. In addition, JP-A-8-311
In 388, a method of improving writing performance such as tip leakage and fluffiness and crying is proposed, but problems such as character breakage, directionality occur and ink followability deteriorates, and writing performance of ballpoint pen Is not satisfied enough.

Further, in JP-A-2-233785, the average particle size is 0.01 to 1.0 μm and the oil absorption is 50 cc / 100.
Although a method of adding a powder having a large structure of g or more has been proposed, it is difficult to completely prevent tip leakage even when mounted on an ink having a relatively low viscosity even under normal temperature and humidity conditions. is there. In addition, JP-A-10-1
95365 and Japanese Patent Application Laid-Open No. 10-204368 propose a method of containing fine particle silica having a primary particle diameter of 7 to 40 nm or a specific surface area of 50 to 380 m ² / g, but it is possible to surely prevent tip leakage. However, the mechanism causes a problem that writing performance becomes very poor, and the writing performance of the ballpoint pen is not sufficiently satisfied.

Further, Japanese Patent Laid-Open No. 11-116879 proposes a method for solving the problem by neutralizing a crosslinked acrylic acid polymer with triethanolamine and a water-insoluble organic amine and swelling it, but it can be used. It has been found that such additives are limited and have poor long-term stability.

[0007]

DISCLOSURE OF THE INVENTION The inventors of the present invention have conducted extensive studies to solve the above problems, and as a result, by adding acrylic ultrafine particles to the ink for ballpoint pens, the viscosity of the ink for ballpoint pens was increased to 25 ° C. Shear rate 9.60
It was found that the above object can be achieved even under the condition of S ⁻¹ of 1,500 to 8,000 mPa.s, and the present invention has been completed. The object of the present invention is good stability over time, No tip leakage occurs when used not only for ordinary single color ballpoint pens but also for composite / multicolored ballpoint pens under conditions of humidity and / or high temperature and high humidity.
Another object of the present invention is to provide an ink capable of providing a smooth writing taste and a ballpoint pen using the ink.

[0008]

The gist of the present invention is a ball-point pen ink containing a colorant, a resin, a solvent, and an additive, and containing acrylic ultrafine particles,
The ballpoint pen ink further contains acrylic ultrafine particles, and the ballpoint ink has a shearing speed of 9.60 S ^-1 at 25 ° C. of 1,500 to 8,000 mPa.s.
It is an ink for a ball-point pen characterized by being s,
It is a ballpoint pen filled with this. The average particle size of the acrylic ultrafine particles is preferably in the range of 0.05 to 1.0 μm, and the addition amount to the ink is preferably in the range of 0.01 to 10.0% by weight. . Furthermore, the present invention utilizes the high yield value resulting from pseudoplastic flow caused by containing acrylic ultrafine particles, and prevents the tip leakage phenomenon at the tip of the ballpoint pen tip when storing the ballpoint pen even with relatively low viscosity ink, Moreover, the ink flows out easily from the tip of the tip by flowing easily when writing with a light writing pressure,
You can get smooth writing.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The ink of the present invention contains ultrafine acrylic particles, has a viscosity of 25 ° C. and a shear rate of 9.60 S.
^-1 has a characteristic of 1,500 to 8,000 mPa.s.

The acrylic ultrafine particles used in the present invention are polymer ultrafine particles in which an acrylate is internally cross-linked and have an average particle diameter of 0.05 to 1.0 μm. Reactive monomers that can be used in the acrylic ultrafine particles synthesized by emulsion polymerization include ethyl acrylate and
Methyl acrylate, n-propyl acrylate, i-
Propyl acrylate, n-butyl acrylate, i-
Butyl acrylate, t-butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, n-
Octyl acrylate, nonyl acrylate, decyl acrylate, undecyl acrylate, lauryl acrylate, myristyl acrylate, cetyl acrylate, stearyl acrylate, 2-methoxymethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, benzyl acrylate, 2-
Examples thereof include acrylic acid esters such as hydroxyethyl acrylate, glycidyl acrylate, and neopentyl glycol dimethacrylate. As these reactive monomers, one type or two or more types of acrylic can be appropriately selected and used according to desired particles. The addition amount is 0.01 to 10.0% by weight, preferably 0.01 to 5.0% by weight, based on the total amount of the ink. If the average particle size is smaller than 0.05 μm, the desired pseudo-plastic fluid cannot be obtained, and the effect of preventing tip leakage is weak.
If it exceeds μm, the yield value becomes too high and the ink is difficult to flow out smoothly, which is not preferable. These acrylic ultrafine particles are first dispersed in the organic solvent of the ink to be used and then added to the ink so that the required concentration is obtained.

As the organic solvent used in the present invention, a known solvent in which alcohols, glycols, glycol ethers and colorants, resins and additives can be obtained as oily ballpoint pens to obtain a desired dissolving power and dispersing power can be used. is there. Specifically, benzyl alcohol, phenoxyethanol,
Ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, glycerin, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol Examples include monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monophenyl ether, triethylene glycol monobutyl ether, propylene glycol monophenyl ether, tripropylene glycol monomethyl ether, and tripropylene glycol monobutyl ether. These organic solvents can be used alone or in combination of two or more, and the content is 30 to 9
It is 0% by weight.

The colorant used in the present invention is usually
It is possible to use known dyes and pigments used in writing instruments and paint inks. As the dye, an alcohol-soluble dye, an oil-soluble dye, a metal-containing dye, a basic dye, an acid dye, a direct dye, and various salt-forming dyes can be used. For example, Nigrosine base, Spiron Black GMH Special, Spiron Blue # 111, Spiron Violet C-RH, # 510, Spiron Red #.
530, same C-GH, same C-BH, spirone orange #
6, the same GRH, Spyron Yellow 2GH, the same C-GH,
Same # 510, Same # 530 (above, Hodogaya Chemical Co., Ltd.), Varifast Black # 1802, Same # 180.
5, # 3820, Varifast Blue # 1601, Varifast Violet # 1701, Varifast Yellow AUM, # 3104, Varifast Red # 23.
20, No. 1320 (all manufactured by Orient Chemical Industry Co., Ltd.), auramine, rhodamine, methyl violet red base, Victoria blue base and the like.

As the pigment, an inorganic pigment or an organic pigment can be used as it is, and a processed pigment or a dispersed toner whose surface is modified with a resin or a surfactant can also be used. Examples thereof include titanium oxide, carbon black, metal powder, phthalocyanine pigment, azo pigment, anthraquinone pigment, quinadrine pigment, nitro pigment and nitroso pigment.

These colorants may be used alone or in combination of two or more. Further, the addition amount is not particularly limited as long as it is an amount depending on the solubility and dispersive power of the colorant or an amount suitable for a desired hue and concentration. The preferred content is 5 to 40% by weight.

In the present invention, it is preferable to use a spinnability imparting agent. Examples of the spinnability imparting agent include polyvinylpyrrolidone and polyvinyl alcohol. It is a known material that is used to prevent phenomena such as crying and bloating on the pen tip during writing, but as a result of intensive research, its mechanism is not clear, but by using it in combination with acrylic ultrafine particles, Improves the fluidity of the ink when
It was found that the writing performance such as bloating and crying was improved. The blending amount is 0.1 to 2.0% by weight with respect to the total amount of ink.
If the amount is less than 0.1% by weight, the effect is thin and 2.0
If it exceeds 5% by weight, writing lines and other writing lines will become abnormal, so
It is preferably in the range of 0.1 to 2.0% by weight.

The water-insoluble thickener used in the present invention includes
Examples thereof include ketone resins, rosin resins, sulfamide resins, maleic acid resins, ester gums, xylene resins, alkyd resins and phenol resins. It is a known material used for adjusting the adhesion of a colorant to a paper surface at the time of writing, improving weather resistance and dispersion stability, and adjusting an ink to a desired viscosity. These resins may be used alone or in combination of two or more, and the content thereof is
It is 0.1 to 30.0% by weight.

In the ballpoint pen ink of the present invention, if necessary, it is possible to use an auxiliary agent used in the ballpoint ink, such as an antiseptic agent or a rust preventive agent.

The viscosity of the obtained ink for a ballpoint pen of the present invention is preferably such that the ink viscosity at 25 ° C. and a shear rate of 9.60 S ^{−1 is} in the range of 1,500 to 8,000 mPa · s. (EHD type viscometer 25 ° C 2.5
rpm 9.60S ^-1 manufactured by Toki Sangyo Co., Ltd.). 1,50
If it is less than 0 mPa.s, the ball sinks easily, and the paper fiber or the like is easily caught. If it exceeds 8,000 mPa.s, the characters are broken,
Phenomena such as line skipping and ball sinking occur and good writing lines cannot be obtained.

The ballpoint pen of the present invention comprises a ball, a pen tip composed of a ball holder, an ink containing tube, a pen shaft, and the like, and the ink containing tube is filled with the above-described ink for a ballpoint pen of the present invention.

The gap between the ball at the tip of the ballpoint pen and the holder for supporting the ball is generally several μm to 1 μm.
5 μm, the viscosity is several thousand to several hundred mP.s. The low viscosity ink of s easily flows out through the gap. The ink for a ballpoint pen of the present invention utilizes a high yield value resulting from pseudo-plastic flow caused by containing ultrafine acrylic particles, and prevents even a relatively low viscosity ink from leaking at the tip of the ballpoint pen tip during ballpoint pen storage. To do. Furthermore, since the ink of the present invention is an ink using resin fine particles, it easily flows when writing with a light writing pressure, so that the writing feel is smooth like an aqueous ballpoint pen.

[0021]

The present invention will be described in more detail by way of examples. The ball-point pen used in the test had a polypropylene ink storage tube with an inner diameter of 2.0 mm and a stainless tip (balls were made of cemented carbide and had a diameter of 0.7 mm). The inks obtained in Examples and Comparative Examples were used. It was filled and mounted on our oil-based ballpoint pen (trade name: Object K4) and evaluated in the following test. The present invention is not limited to this embodiment.

Test item 1) The value measured by an E-type viscometer (manufactured by Toki Sangyo Co., Ltd.) at a viscosity of 25 ° C. and a shear rate of 9.60 S ^-1 in mPa.s. 2) Tip leakage test With the tip of 20 ballpoint pens filled with the specified ink facing down, place it in a thermo-hygrostat at a temperature of 40 ° C and a relative humidity of 60%.
After leaving it for a day, the degree of tip leakage was examined, and ⊚ was evaluated for almost nothing, ∘ for slightly present, Δ for slightly more, and x for very much. 3) Writing taste test It was evaluated by handwriting. 4) Writing test A ballpoint pen filled with a predetermined ink is left at room temperature for 24 hours and then written. At that time, the distance until the writing line was visually recognized was measured.

Example 1 Acrylic ultrafine particles are dispersed in a main solvent with a sand mill. Separately, use a high-speed propeller stirrer to
After stirring and mixing at a temperature of 0 ° C. or lower, the above dispersion liquid was stirred and mixed to produce a ballpoint pen ink.

Example 2 The same formulation as in Example 1 was used.

Example 3

Example 4 The pigment is dispersed in the main solvent using a homogenizer. Separately, the acrylic ultrafine particles dispersed in the main solvent by a sand mill and the rest of the materials were charged and further stirred and mixed at a temperature of 100 ° C. or lower to produce a ballpoint pen ink.

Comparative Example 1 Using a high speed propeller stirrer, an ink for a ballpoint pen was produced at a temperature of 100 ° C. or lower with the following composition.

Comparative Example 2 The same composition as in Comparative Example 1 was used.

Comparative Example 3 The same composition as in Example 1 was used.

Comparative Example 4 The same formulation as in Example 1 was used.

Comparative Example 5 The same formulation as in Example 1 was used.

Comparative Example 6 The pigment is dispersed in the main solvent using a homogenizer. Then, the pigment dispersion liquid, the fine particle dispersion liquid, and the remaining materials were stirred and mixed at a temperature of 100 ° C. or less to produce an ink for a ballpoint pen.

Table 1 shows the test results of the ballpoint pen inks obtained in Examples and Comparative Examples.

[Table 1]

From the results in Table 1, it is clear that the inks of the examples prevent the tip leakage phenomenon at the tip of the ballpoint pen during storage of the ballpoint pen, and provide a smooth writing feel during writing.

[0035]

INDUSTRIAL APPLICABILITY According to the present invention, the fluidity of ink during storage of a ballpoint pen and during writing is improved, and the phenomenon of ink tip leakage at the tip of the ballpoint pen tip is not caused. The ball-point pen filled with this ink was able to obtain a smooth writing feel during writing without causing a blowing phenomenon at the tip end portion.

Claims (6)

[Claims] 1. A ball-point pen ink comprising a colorant, a resin, an organic solvent and an additive, wherein the ball-point pen ink further contains acrylic ultrafine particles, and the ball-point pen ink at 25 ° C., Ink viscosity at a shear rate of 9.60 S ^-1 is 1,500 to 8,000 mPa.s
Ink for ballpoint pens characterized by being 2. The ink for a ballpoint pen according to claim 1, wherein the acrylic ultrafine particles have an average particle size of 0.05 to 1.0 μm. 3. The amount of acrylic ultrafine particles added to the ink is in the range of 0.01 to 10.0% by weight.
Alternatively, the ink for a ballpoint pen according to claim 2. 4. The ink for a ballpoint pen according to claim 1, which contains 0.1 to 2.0% by weight of a spinnability imparting agent. 5. The ink for a ballpoint pen according to claim 1, which contains 1 to 30.0% by weight of a water-insoluble thickener. 6. A ball-point pen filled with the ink for a ball-point pen according to any one of claims 1 to 5.