JPH09124993A - Thermochromic water-base ballpoint ink and ballpoint pen using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermochromic water-base ballpoint ink and a ballpoint pen using it, which enable smooth writing and give a thermochromic writing. SOLUTION: This thermochromic water-base ballpoint ink 6 consists of essential constituents comprising a microencapsulated thermochromic pigment, a substance whose viscosity decreases by shear, and an aqueous medium containing water and a water-soluble organic solvent, wherein the microencapsulated pigment is dispersed in the aqueous medium. The ballpoint pen 1 is provided with such a tip structure as to properly deliver the ink.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a thermochromic water-based ballpoint pen ink and a ballpoint pen using the same.

[0002]

2. Description of the Related Art Several proposals have been disclosed for water-based ballpoint pen inks that are made writable by reducing the viscosity by the shearing action caused by the rotation of the ball during writing (Japanese Patent Publication No. 64-8673, Japanese Patent Publication No. Fair 7-17872
No.). However, no effective proposal has been disclosed yet for a water-based ballpoint pen that gives thermochromic handwriting.

[0003]

The present inventor has earnestly pursued a ball-point pen ink containing a thermochromic microcapsule pigment and a ball-point pen mechanism for effectively drawing out the ball-point pen ink, and has a smooth writing feeling and a uniform writing feeling. Disclosed is a thermochromic ballpoint pen ink capable of continuously forming stable thermochromic handwriting and a ballpoint pen using the same.

Conventionally, a solid writing material in which a thermochromic microcapsule pigment is dispersed in an excipient such as wax has been disclosed in JP-B-51-48085. , Had some problems. First, there is a problem that the microcapsules are broken by the writing pressure during writing as the main reason. That is, when a dispersion ink of a thermochromic microcapsule pigment is applied in a system that is made into a highly viscous oil-based ink and is derived from an oil-based ballpoint pen mechanism, the handwriting density is insufficient, and the microcapsule pigment itself is a brush when writing. It is apt to be destroyed by pressure, and proper thermochromic handwriting cannot be continuously formed. Such a phenomenon can be easily understood in consideration of the fact that pressure-sensitive copying paper, so-called carbonless paper, can be copied on the bottom sheet side by writing with a ball-point pen and breaking it.

In recent years, an aqueous ballpoint pen using an ink of an aqueous medium to which thixotropy is imparted has been put into practical use. This type of ink has the characteristic that it has a high viscosity when it is allowed to stand, and a low viscosity when it is highly sheared during writing.The ink ejection mechanism at the tip part is based on the non-shear thinning oil-based ballpoint pen ink system. It is very different compared to. That is, the difference between the inner diameter of the ball housing portion and the outer diameter of the ball is large, that is, the gap is large, and the ink whose viscosity has been reduced by the shearing action passes through the gap by the capillary action and is transferred to the paper surface. The present inventor first ensures the passage of the gap by adjusting the size of the microcapsule pigment particles in a predetermined particle range sufficient to pass through the gap, and further, in the above-mentioned problem of destruction and deterioration of the microcapsule. On the other hand, the viscosity of the ink during writing is about 160 m.s. Pa. It has been found that when it is s or less, the capsule pigment particles move so as to slip out of the writing pressure and have a pressure relaxation property. It was also found that as the viscosity of the ink becomes higher, the ejection property of the ink becomes poorer, and at the same time, the degree of escape from the writing pressure of the capsule pigment itself decreases, so that the capsule pigment particles tend to break accordingly. It was

Further, as a result of earnest research, the shape of the microcapsule pigment has a shape having depressions (recesses) on its surface, as compared with a spherical body having a perfect circular cross section (see FIG. 1).
It was found that even with ink having the same viscosity, the degree of destruction of the capsule itself is further alleviated. It is considered that the microcapsule pigment having the dents (recesses) is caused by the stress being relieved by the elastic deformation of the microcapsule pigment even if the microcapsule pigment receives an external force (pressure generated during writing). In fact, in this kind of thermochromic microcapsule pigment, the phase change of the thermochromic composition (homogeneous phase solution) which is the inclusion due to the change of temperature, that is, liquid phase (color development) and solid phase (erasing) The volume expansion coefficient of the encapsulated material changes accordingly when the color is reversibly changed, and at the same time, the capsule membrane is deformed by the internal pressure and follows the phenomenon. Based on the above-mentioned findings, the present inventor constructed a ballpoint pen ink of an aqueous medium using a thermochromic microcapsule pigment, which has been considered difficult in the past, as a colorant, and applied it in combination with a specific ballpoint pen mechanism to generate heat. We succeeded in being able to continuously form a uniform handwriting without any deterioration of the color-changing function.

A problem with the second thermochromic microcapsule pigment is handwriting density. In recent years, in water-based ballpoint pens, water-based ballpoint pens that use fluorescent pigments, gold, and silver pigments in addition to those using general dyes and pigments as colorants have been commercially available. The biggest difference between the dye and pigment system as described above and the microencapsulated thermochromic pigment system relates to the color density of the pigment particles themselves.

The thermochromic microcapsule pigment contains, in addition to an electron-donating color-developing organic compound such as a leuco dye and an electron-accepting compound such as a phenolic compound as an encapsulating material, in order to control the color-changing temperature, Various organic medium compounds having a polarity of about 20 to 50 times by weight that of the above-mentioned two compounds are blended. As a result, the leuco dye, which determines the original concentration, is about 20% in the state of the encapsulating composition.
It is diluted about 50 times.

In an attempt to increase the concentration of the microcapsule pigment itself, the ratio of leuco dye and corresponding phenolic compound can be increased. However,
Increasing the density of the pigment particles themselves by such a method causes a residual color at the time of erasing with respect to the thermochromic function, resulting in a decrease in contrast at the time of discoloring such as lack of handwriting magic. The present inventor diligently studied the relationship between the solid content concentration and the handwriting concentration of the thermochromic microcapsule pigment, and as a result, the microcapsule pigment in the ink composition was in the range of 5% by weight or more and 45% by weight or less. , Can form handwriting as a ballpoint pen. However, 5
In the system of up to 15% by weight, there is no problem in the ink ejection property, but the handwriting density (concentration that makes the thermochromic effect of the handwriting visible clearly) is insufficient, and in practice, 15% by weight or more is practically used. It is difficult to satisfy the density of handwriting unless it is blended, and as the blending amount increases, it tends to be possible to form high-density handwriting, but even if the shear thinning effect at the time of writing is added, 40
If it exceeds 5% by weight, the ink ejection property tends to deteriorate. Considering the above-mentioned ink dischargeability, handwriting density, and shear thinning property imparted to the ink, the most preferable solid content concentration of the thermochromic microcapsule pigment is 20% by weight or more,
It was found to be 0% by weight or less. The present invention has been completed by further studying on the basis of the above-mentioned knowledge and combining this with an appropriate ballpoint pen mechanism.

[0010]

The thermochromic ballpoint pen ink of the first invention will be described. The ink of the present invention comprises (a) a thermochromic microcapsule pigment, (b) an aqueous medium containing a shear thinning substance, water and a water-soluble organic solvent as essential components, and the microcapsule pigment is dispersed in the aqueous medium. It is required to be in a state. Furthermore, the thermochromic microcapsule pigment is obtained by coating a wall film with a homogenous compatible solution containing an electron-donating organic compound, an electron-accepting compound and a reaction medium for controlling the color-changing temperature as essential components. It is a pigment that occupies 95% by volume or more in the range of 0.5 μm to 20 μm, and the thermochromic microcapsule pigment is composed of a wall film formed by an interfacial polymerization or an interfacial polycondensation method having depressions on at least a part of the outer surface. Pigment, 15 to 45% by weight (solid content) of thermochromic microcapsule pigment whose particle distribution occupies 95% by volume or more in the range of 0.5 to 20 μm, shear thinning resin 0.1 to
0.5% by weight, containing 5 to 35% by weight of water-soluble organic solvent,
The balance is water, and the viscosity is 40 to 160 m. Pa. s
It is in the range of (value at 100 rpm in EM type rotational viscometer) and satisfies the shear thinning viscosity index of 0.1 to 0.6, and the like.

The shear thinning viscosity of the above-mentioned ink is an exponential exponential formula (T = K) obtained from a rheological measurement by a viscometer such as a shear stress value (T) and a shear rate (j) value.
j ⁿ : K and n are calculated constants). As the n value, 0.
1 to 0.6, preferably 0.20 to 0.60 is effective. Outside the above range, the effect due to shear thinning is not appropriate, and ink dischargeability and handwriting performance are impaired. In connection with this, the viscosity of the ink depends on the high shear rate (specifically 100 rpm, 25 rpm) generated by the ball rotation during writing.
40-160 m. Pa. S, preferably 60-1
40 mPa. S range of 160 mPa.s. If it exceeds S, defective ink ejection properties occur. The appropriate range that does not cause scratches on the handwriting, line breaks, ink drops, etc. is the range described above. By configuring the ink having the above-mentioned physical property values, it is difficult for the ink to flow in the ink containing tube due to the thixotropic property, but as the ink is used, it moves due to the viscosity of the ink, and the ink is stirred at a high speed in the ball containing portion. Therefore, the viscosity is low and the ink is properly ejected.

The thermochromic material, which is an encapsulated material and is composed of a homogeneous compatible solution of the above-mentioned electron-donating color-developing organic compound, electron-accepting compound and color-changing temperature controlling agent, is emitted at a predetermined temperature by an electron transfer reaction. A conventionally known type that erases color,
For example, JP-B-51-44706 and JP-B-51-44
708, Japanese Patent Publication No. 52-7764, Japanese Patent Publication No. 51-35
No. 414, Japanese Patent Publication No. 1-29398, Japanese Patent Laid-Open No. 7-1
86546, etc., Japanese Patent Publication No. 4-17154 previously proposed by the present applicant, and Japanese Patent Laid-Open No. 7-1.
No. 79777, JP-A No. 7-33997, etc., a thermochromic material containing a color-memory thermosensitive dye that exhibits large hysteresis characteristics and changes color (that is,
The shape of the curve plotting the coloring density due to temperature change has a significantly different path depending on whether the temperature rises from the lower temperature side than the discoloration temperature range or on the contrary lowers from the higher temperature side than the discoloration temperature range. Type that follows discoloration: It is effective to be able to store and retain the appearance of changes at temperatures below the low temperature side discoloration point or above the high temperature side discoloration point in the normal temperature range between the low temperature side discoloration point and the high temperature side discoloration point. .

The microencapsulation is carried out by a conventionally known interfacial polymerization method, interfacial polycondensation method, in situ polymerization method, in-liquid curing coating method, coacervate method or other phase separation method from an aqueous solution, or a phase separation method from an organic solvent. There are a melt dispersion cooling method, an air suspension coating method, a spray drying method and the like, which are appropriately selected according to the application. Examples of the microcapsule pigment 5 effective in the present invention include those in which the inclusions are covered with the wall film 51, as illustrated in FIGS. 1 to 5, and may have the depressions 52. A single system of these shapes,
Alternatively, a mixed system is effective. Apart from this, it may be in the form of solid solution. Incidentally, the surface of the microcapsules may be provided with a secondary resin coating to impart durability, or the surface characteristics may be modified for practical use according to the purpose. As an ink for water-based ballpoint pens, in order for the ink to smoothly move in a relatively narrow gap between the ball and the ball containing portion, the thermochromic microcapsule pigment is basically preferably a mononuclear pigment, and is not required to have a small size. Easy,
An encapsulation method with a more uniform particle size is preferred.

As a result of studying various microencapsulation methods in this regard, microcapsules obtained by a phase separation method from an aqueous solution such as a coacervate method are used in an aqueous medium because a hydrophilic resin is used as an encapsulating material. Since the crosslinked film itself has a water swelling property, the film thickness is large in the particle size, which is disadvantageous in obtaining an effective handwriting density. Examples of the in-situ encapsulation from the aqueous phase include a method of reacting a urea-formalin initial condensate with a catalyst to form a film from the outside of the inclusion. The point is that agglomerated particles are likely to occur.
The agglomerates formed during the reaction are mixed into the ink without being re-dissociated, and finally are cumulatively trapped in the space between the ball and the ball accommodating portion, so that writing failure is likely to occur. The spray-drying method or other encapsulation methods also tend to cause similar problems.

As a result of studying the most preferable encapsulation method satisfying the above-mentioned performance, the inventor of the present invention basically uses an interfacial polymerization method or an interfacial polycondensation method of reacting at the interface between an aqueous phase and an oil phase to form a membrane wall. The encapsulation method has an advantage that the particle size set by emulsification can be easily maintained even after the capsule is finished, because the particle distribution is narrow and aggregation does not occur. Furthermore, the external shape of the capsule obtained by the method has at least one depression (recess), and has a hemispherical flat appearance as a whole.

When used as an ink for a water-based ballpoint pen, such a special shape has the following advantages.
One is that the pressure during writing can be relieved by deforming the pressure itself, and breakage and deterioration of the capsule can be significantly reduced.
Another advantage is that the hemispherical flat microcapsule pigment has a difference between the inner diameter of the ball receiving portion and the outer diameter of the ball of 20μ.
m, that is, when one side passes through a gap of 10 μm,
The true spherical microcapsule pigment has a diameter of 10 μm.
If it exceeds, it will be difficult to eject. The hemispherical flat microcapsule pigment preferably used in the present invention has a good discharge property from the gap even if the major axis direction is approximately 15 μm if the minor axis direction is 5 μm. It is considered that the capsule pigment is ejected while being oriented along the streamline direction of the ink flow direction. In practice, the average particle size is made smaller so that the particle size is set so that it can more easily pass through the narrowest gap between the ball and the ball housing portion. With respect to the ejection of the capsule-containing ink having a distribution, it has a great advantage.

The ink of the present invention is not limited to microcapsule pigments having a single thermochromic point, but pigments having a plurality of colorchanging points and general non-thermochromic dyes are also included in order to diversify the change. A pigment or the like can be used together.

As the shear thinning substance, a substance which is substantially soluble in water is effective, and xanthan gum, welan gum, and succinoglycan (average molecular weight), whose constituent monosaccharides are organic acid-modified heteropolysaccharides of glucose and galactose. About 1 to 8 million), guar gum, locust bean gum and its derivatives, hydroxyethyl cellulose, alginic acid alkyl esters, polymers having a molecular weight of 100,000 to 150,000 and containing methacrylic acid alkyl ester as a main component, glycomannan, agar and carrageenan. Examples thereof include gelling-capable carbohydrates extracted from seaweeds such as benzylidene sorbitol, benzylidene xylitol or their derivatives, and crosslinkable acrylic acid polymers, which may be used alone or in combination. In particular, xanthan gum and succinoglycan are preferable because they have stable physical properties even after storage for a long period of time.

The water-based ball ink containing the thermochromic microcapsule pigment of the present invention has a high content of the pigment as a colorant, so that the microcapsule pigment and the vehicle component containing no shear-thinning resin have already been used. The viscosity is quite high. Therefore, the blending amount of the shear thinning resin cannot be increased, unlike the ink using general dyes and pigments. That is, in the ink composition,
The range of 0.1 to 0.5% by weight is preferable. The most preferred range is 0.10 to 0.30% by weight.

As the water-soluble organic solvent, ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, propylene glycol, butylene glycol, dipropylene glycol, thiodiethylene glycol, sorbitol, glycerin,
Polyhydric alcohols such as polyethylene glycol, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, etc., and wetting agents such as triethanolamine, pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide, urea, ethyleneurea, and thiourea.
Other water retention agents and the like can be used alone or in combination. These are selected according to the purpose of suppressing the drying of the ink at the tip of writing, imparting water resistance to the handwriting, or a solubilizing agent for the dye, and are used in the range of 5 to 35% by weight in the ink composition. Water is used as the main solvent.

Other aqueous media include various surfactants for improving the fluidity of ink and stabilizing dispersion, polyvinylpyrrolidone, polyvinyl alcohol, and water-soluble acrylic for the purpose of preventing handwriting bleeding and as a protective colloid of pigments. resin,
If necessary, a water-soluble resin such as arabic rubber, a lubricant, a moisturizer, an antiseptic such as sodium benzoate and sodium dehydroacetate, an anticorrosive such as benzotriazole, an antifoaming agent and the like can be added.

The specific gravity of the microcapsule pigment is 25
Although it is generally in the range of 0.95 to 1.05 at ° C, the storage stability can be improved by appropriately adjusting the specific gravity in combination with the vehicle. Usually, it is preferable to adjust the difference in specific gravity between the microcapsule pigment and the vehicle within the range of 0.05. There are two methods of adjusting the specific gravity, one is a method of adding a compound having a large specific gravity in a range that does not affect the thermochromic function and does not deteriorate the color changing function, and the other is a minute method. A film agent having a specific gravity of more than 1 is applied when forming the capsule.

These methods are effective in reducing the difference of the specific gravity of the fine particles smaller than 1 and the difference in specific gravity from the aqueous vehicle to 0.1 or less, when the difference is 0.1 or more. When the difference in specific gravity is more than 0.05 and less than 0.1, it can be adjusted by microencapsulation with an ordinary film agent.

Examples of the compound having a large specific gravity include halides, for example, chlorine, bromine, and iodine as halogen atoms, and bromine, which has a large effect of increasing specific gravity and is present in various kinds of compounds, is preferable. Specifically, hexabromobenzene, hexachlorobenzene, brominated phenylmethacrylic acid ester, brominated phenylacrylic acid ester, tetrachlorobisphenol A, decabromobiphenol ether, dibromostearic acid ester, chlorinated paraffin, tris (2,3- Dibromopropyl) phosphate, dibromophenol, 2,3
-Dibromopropanol, tetrachlorophthalic anhydride,
Perchlorpentacyclodecane, tetrabromobutane,
Examples thereof include halogen-substituted aromatic and aliphatic compounds having a specific gravity of 1.2 or more such as chlorinated polyphenyl.

As the film agent used for adjusting the specific gravity, a main agent and a curing agent or a catalyst are used which form the film agent without inhibiting the color-changing function of the inclusions and have the effect of increasing the specific gravity.

When the difference in specific gravity between the thermochromic composition and the inclusion is relatively large (specific gravity difference> 0.1), and it is difficult to adjust the specific gravity with an ordinary film forming agent, a halogen-substituted resin is preferable,
For example, brominated epoxy resin, chlorinated epoxy resin, brominated unsaturated polyester resin, brominated acrylic resin, brominated urethane resin, brominated styrene, vinyl chloride, vinylidene chloride, etc. The thing used is mentioned. One kind or two or more kinds of these resins are appropriately used in combination with a curing agent or a catalyst to be used as a film agent for microcapsules.

When the specific gravity of the thermochromic composition is approximately 1 and is close to the specific gravity of the aqueous vehicle, it is not always necessary to add the above-mentioned halogen-containing compound or halogen-containing resin, and fine adjustment with a usual film agent is required. Good.

Next, the drawings relating to the ballpoint pen of the second invention will be described (see FIGS. 6 to 11). A ball-point pen 1 applied to the present invention is a ball-point pen 1 that is provided with a tip that holds a ball 2 rotatably, and that is configured to draw out ink stored in an ink storage unit 4 so that writing is possible.
The ink containing portion is composed of (a) a thermochromic microcapsule pigment, (b) an aqueous medium containing a shear thinning substance, water and a water-soluble organic solvent, and the microcapsule pigment is in a dispersed state in the aqueous medium. A discolorable water-based ballpoint pen ink 6 is filled. Further, an ink follower is arranged in contact with the rear end portion of the thermochromic ball-point pen ink 6 accommodated in the ink accommodating portion 4, and the ball accommodating portion 3 that rotatably holds the ball 2 is provided. The difference between the inner diameter A of the ball 2 and the outer diameter B of the ball 2 is 10 to 60 μm, and the difference between the inner diameter A and the ball outer diameter B of the ball accommodating portion 3 that rotatably holds the ball 2 is 10 to 60 μm. And the ball 1 is provided with a space C capable of moving in the axial direction of 20 to 100 μm. The thermochromic water-based ballpoint pen ink 6 has a particle size distribution of 0.5 to 20 μm and is 95% by volume in thermochromic color. Microcapsule pigment 15-45% by weight (solid content), shear thinning resin 0.1-0.5% by weight, water-soluble organic solvent 5-35% by weight, the balance being composed of water, viscosity Is 40 to 160 m. Pa. s (value at 100 rpm of EM type rotational viscometer),
It satisfies the shear thinning index of 0.1 to 0.6. In the above, the inner diameter A of the ink containing portion 3 and the outer diameter B of the ball
Difference from 10 to 60 μm, more preferably 15 to 40 μm
By setting m, a smooth writing feeling is satisfied and a handwriting with an appropriate density is given. The length of the ball 2 that can be moved in the axial direction is 20 to 100 μm, preferably 40 to
By setting the thickness to 80 μm, the ejection property for satisfying the appropriate handwriting density is satisfied.

As for the structure of the writing tip as described above, a general-purpose mechanism has been conventionally effective, and the ink containing portion 4 is integrally formed by pressing and deforming the vicinity of the tip of the metal pipe inward from the outer surface. The mechanism (see FIGS. 6 to 7), or
A mechanism for forming the ink containing portion 4 by cutting a metal material with a drill or the like, and arranging the ball receiving seat 33, the central hole 31, and the radial lead-out groove 32 (see FIGS. 8 to 9) or a spring body. Mechanism that urges the ball forward (Fig. 1
0) etc. can be applied.

The ink follower 7 is for preventing ink leakage and the like when the ballpoint pen 1 is turned upside down or sideways, and is immiscible and insoluble with the ink, and is a conventionally known viscous agent such as polybutene. A gel-like backflow preventer based on an elastic body or silicone oil is particularly effective, but a conventionally known solid stopper or the like may be used.

The balls 2 may be made of cemented carbide, stainless steel, ruby, ceramics or the like having a diameter of 0.3 to 1.2 mm.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. The term "parts in the formulation" in the examples means parts by weight. Example 1 A method for preparing the thermochromic microcapsule pigment used in this example is described. A thermochromic composition comprising 2 parts of 6- (ethylisobutylamino) benzofluorane, 6 parts of bisphenol A, 30 parts of cetyl alcohol and 20 parts of stearyl caprate, and 1 part of tinuvin 326 as a light resistance imparting agent, and then as a film material. Epoxy equivalent 190 obtained by reaction of bisphenol A with epichlorohydrin
15 parts of the epoxy resin of 1 was uniformly heated and dissolved, and emulsified with 100 parts of the aqueous protective colloid medium preheated at 70 ° C. with a homomixer so that the average particle diameter was 5 μm. Then, 5 parts of an aliphatically modified polyamine curing agent was added and stirring was continued at 90 ° C. for 5 hours to obtain a microcapsule dispersion liquid by an interfacial polymerization method. Centrifugation treatment was performed for the purpose of concentrating the microcapsules, and the water-containing cake 1
I got 00 parts. The water content of the capsule slurry was measured and found to be 38%.

Further, in order to measure the particle size distribution, a centrifugal sedimentation type automatic particle size distribution measuring device (manufactured by Horiba, CAPA-30)
0) was used. When the particle diameter is D, the relationship between the particle diameter and the occupied volume% [shown in ()] was as follows. In the above, a total of 98 of 0.5 μm ≦ D ≦ 20 μm
%, And the average particle size is 4.2 μm.

When the obtained microcapsules were observed with a microscope, it was confirmed that they were hemispherical flat capsules having concave portions. Flatness increased as the particle size increased. The thermochromic properties of the thermochromic microcapsule pigment were magenta at 27 ° C. or lower, colorless at 32 ° C. or higher, and a transitional range of discoloration between both temperatures.

An aqueous ballpoint pen ink was prepared using the obtained microcapsule slurry as a colorant. An example of the formulation is shown below. [Parts by weight] Microcapsule slurry 44.00 (solid content 27.3%) Xanthan gum 0.33 Water 32.86 Urea 11.00 Glycerin 11.00 Nopco SW-WET-366 0.55 Nopco 8034 0.13 Proxel XL -2 0.13 ─────────────────────── Total 100.00

The viscosity of the ink was measured with an EMD type viscometer.
As a result of measurement at 5 ° C., 10 rpm at 1 rpm. Pa.
84 m.s. at 100 rpm. Pa. s, and the shear thinning index was n0.48. In addition, Nopco SW-WE
T-366 is a nonionic penetrating agent manufactured by San Nopco, Nopco 8034 is a modified silicone defoaming agent manufactured by San Nopco, and Proxel XL-2 is an I.D. C. It is a benzothiazoline preservative manufactured by Company I.

Preparation of Ballpoint Pen Using a 0.8 mm stainless steel ball, a difference S (A−B) between the inner diameter of the ball receiving portion and the outer diameter of the ball = 20 μm, and a space C = 70 μm movable in the axial direction are provided. A cutting type ball-point pen tip which is arranged is used. 0.8 g of the thermochromic ink was suction-filled into a polypropylene pipe having an inner diameter of 3.3 mm and was connected to the ballpoint pen tip through a resin holder. Then, from the tail of the polypropylene pipe, fill a polybutene-based viscoelastic ink follower (liquid stopper), and after incorporating the external pen shaft, cap, cap, and tail stopper, centrifuge and de-air treatment. Then, a thermochromic water-based ballpoint pen was obtained. When writing on a report paper with the thermochromic water-based ballpoint pen, good pink density and handwriting were obtained from the writing. Then, the user continued to write, but all of the ink could be consumed without any undesired phenomena such as ink dripping, remarkable line breakage, blurring, and handwriting skipping. Furthermore, in order to confirm the destruction / deterioration of the microcapsules due to the writing pressure during writing, the ink on the written paper surface was collected, and the appearance of the capsules was examined under a microscope. No capsule destruction was observed. .

As a result of testing the thermochromic property of the handwriting, it showed magenta color at 27 ° C. or less and colorless thermochromic property at 32 ° C. or more. It showed the same thermochromic property as the microcapsule slurry used as a raw material for inking, and it was confirmed that the thermochromic function was maintained after writing. Separately, a ballpoint pen having the same specifications was prepared and left for 30 days in a constant temperature chamber at 50 ° C in an upright, inverted, and horizontal state, and then a writing test was performed. As a result, good results were obtained as in the initial test. Obtained.

Example 2 2- (4-diethylamino-2-ethoxyphenyl)-
3- (1-ethyl-2-methylindol-3-yl)
A thermochromic composition comprising 2.5 parts of -4-azaphthalide, 5 parts of 2,2-bis (4-hydroxyphenyl) hexafluoropropane and 50 parts of neopentyl stearate and 1 part of tinuvin 326 as a light resistance imparting agent; Then, 15 parts of an oligomer obtained by reacting an aromatic diisocyanate and glycol with a film material was dissolved by heating together with 30 parts of a co-solvent, and the average particle size was added to 100 parts of the aqueous protective colloid medium preheated at 70 ° C. The mixture was emulsified with a homomixer so that the diameter was 2.5 μm. Then, 5 parts of an aliphatically modified polyamine curing agent was added, and stirring was continued at 90 ° C. for 5 hours to evaporate and remove the cosolvent to obtain a microcapsule dispersion liquid by an interfacial polymerization method. Centrifugation treatment was performed for the purpose of concentrating the microcapsules to obtain 98 parts of a slurry-like water-containing cake. 32% when the water content of the capsule slurry was measured
Met.

Further, in order to measure the particle size distribution, a centrifugal sedimentation type automatic particle size distribution measuring device (manufactured by Horiba, CAPA-30)
0) was used. When the particle diameter is D, the relationship between the particle diameter and the occupied volume% [shown in ()] was as follows. The cumulative total of 0.5 μm ≦ D ≦ 20 μm was 97%, and the average particle size was 2.7 μm.

When the obtained microcapsules were observed under a microscope, hemispherical flat capsules having concave portions (see FIG. 2) were obtained.
(See ~ 5). Flatness increased as the particle size increased. The thermochromic properties of thermochromic microcapsule pigments are blue at 32 ° C and below 32 ° C.
It was colorless above 0 ° C, had a wide hysteresis characteristic between both temperatures, and was capable of producing the two states of color. An aqueous ball-point pen ink was prepared using the obtained microcapsule slurry as a colorant. An example of the formulation is shown below. [Parts by weight] Microcapsule slurry 53.92 (solid content 36.7%) Xanthan gum 0.24 Water 32.60 Urea 11.00 Glycerin 0.88 Nopco SW-WET-366 1.10 Nopco 8034 0.13 Proxel XL -2 0.13 ───────────────────────── Total 100.00

The viscosity of the ink was measured with an EMD type viscometer.
As a result of measuring at 5 ° C., at 1 rpm, 1306 m.p.m. Pa.
122 m.s. at 100 rpm. Pa. s, shear thinning index n0.49.

Preparation of Ballpoint Pen Using a 0.5 mm stainless steel ball, a difference S (A−B) between the inner diameter of the ball receiving portion and the outer diameter of the ball = 20 μm, and a space C = 40 μm movable in the axial direction are provided. A cutting type ball-point pen tip which is arranged is used. 0.8 g of the thermochromic ink was suction-filled into a polypropylene pipe having an inner diameter of 3.3 mm and was connected to the ballpoint pen tip through a resin holder. Then, from the tail of the polypropylene pipe, fill a polybutene-based viscoelastic ink follower (liquid stopper), and after incorporating the external pen shaft, cap, cap, and tail stopper, centrifuge and de-air treatment. Then, a thermochromic water-based ballpoint pen was obtained. When writing on a report paper using the thermochromic water-based ballpoint pen, good pink density and handwriting were obtained from the writing. Then, the user continued to write, but all of the ink could be consumed without any undesired phenomena such as ink dripping, remarkable line breakage, blurring, and handwriting skipping.

Further, in order to confirm the destruction / deterioration of the microcapsules due to the writing pressure during writing, the ink on the surface of the written paper was collected and the appearance of the capsules was examined with a microscope. Was not done. As a result of testing the thermochromic property of the handwriting, a blue color at 14 ° C or lower,
It was colorless at 32 ° C. or higher, and showed the same color change property as that of the capsule slurry used as a raw material for making an ink in hysteresis characteristics between both temperatures.

Example 3 Using the same capsule slurry (moisture content 38%) as in Example 1, the type of shear thinning resin in the ink formulation was changed to succinoglucan, and the addition amount was also an appropriate viscosity. changed.

The specifications of the ballpoint pen followed the same method as in Example 1. An example of ink formulation is shown below. [Parts by weight] Microcapsule slurry 44.00 (solid content 27.3%) Succinoglucan 0.24 Water 32.95 Urea 11.00 Glycerin 11.00 Nopco SW-WET-366 0.55 Nopco 8034 0.13 Proxel XL-2 0.13 ───────────────────────── Total 100.00

Example 4 The same capsule slurry (moisture content of 38%) as in Example 1 was used, and the type of shear thinning resin in the ink formulation was changed to a cross-linkable acrylic water-soluble resin (Sumitomo Seika, Acpec H).
V501] and changed its weight.

The specifications of the ballpoint pen were the same as in Example 1. An example of ink formulation is shown below. [Parts by weight] Microcapsule slurry 44.00 (solid content 27.3%) ACPEK HV501 0.15 water 33.04 25% ammonia water 0.45 urea 11.00 glycerin 11.00 Nopco SW-WET-366 0. 55 Nopco 8034 0.13 Proxel XL-2 0.13 ───────────────────────── Total 100.00

Example 5 The same ink as in Example 2 was used, and the ballpoint pen tip portion was changed from the cutting type to the pipe pressing deformation type (FIGS. 6 to 7).
A ballpoint pen was manufactured by changing the method. That is, 0.7m
m stainless steel ball was used, and the ball accommodating portion was a ballpoint pen tip having a space S = (A−B) = 30 μm between the pipe inner diameter and the ball outer diameter, and a space C = 25 μm that was axially movable. . 0.8 g of the thermochromic ball-point pen ink was suction-filled in a polypropylene tube having an inner diameter of 3.3 mm and connected to the ball-pe tip through a resin holder. Then, from the tail of the polypropylene tube, fill the polybutene-based viscoelastic ink follower (liquid stopper), and after incorporating the external pen shaft, cap, cap, and tail stopper, centrifuge and deaeration. Then, a thermochromic water-based ballpoint pen was obtained.

When writing on a report paper using the thermochromic water-based ballpoint pen, good pink density and handwriting were obtained from the writing. Then, the user continued to write, but all of the ink could be consumed without any undesired phenomena such as ink dripping, remarkable line breakage, blurring, and handwriting skipping. Furthermore, in order to confirm the destruction / deterioration of the microcapsules due to the writing pressure during writing, the ink on the written paper surface was collected, and the appearance of the capsules was examined under a microscope. No capsule destruction was observed. . As a result of thermochromic test of the handwriting, it was blue at 14 ° C or lower and colorless at 32 ° C or higher, and the hysteresis property between both temperatures was the same as that of the capsule slurry used as a raw material for ink formation. Showed sex.

Example 6 Using the microcapsule slurry of Example 2, a general fluorescent pigment (pink) was blended in the ink formulation to prepare an ink having a color-to-color discoloration property. The fluorescent pigment SW-27 is a pink fluorescent pigment manufactured by Shin Loihi. An example of ink formulation is shown below. [Parts by weight] Microcapsule slurry 53.92 (solid content 36.7%) Xanthan gum 0.24 Water 27.64 Urea 11.00 Glycerin 0.88 Nopco SW-WET-366 1.10 Nopco 8034 0.13 Proxel XL -0.13 Fluorescent pigment SW-27 (pink) 5.00 ────────────────────────── Total 100.00

A 0.5 mm stainless steel ball was used for the above ink, and the difference S (A
-B) = 20 μm, axially movable space C = 4
A ballpoint pen having a cutting type ballpoint pen tip having a space of 0 μm was used. 0.8 g of the thermochromic ball-point pen ink was suction-filled in a polypropylene tube having an inner diameter of 3.3 mm and connected to the ball-pe tip through a resin holder. Then, from the tail of the polypropylene tube, fill the polybutene-based viscoelastic ink follower (liquid stopper), and after incorporating the external pen shaft, cap, cap, and tail stopper, centrifuge and deaeration. Then, a thermochromic water-based ballpoint pen was obtained.

When writing on the report paper, a good purple handwriting was obtained from the writing. Then, the user continued to write, but all of the ink could be consumed without any undesired phenomena such as ink dripping, remarkable line breakage, blurring, and handwriting skipping. Furthermore, in order to confirm the destruction / deterioration of the microcapsules due to the writing pressure during writing, the ink on the written paper surface was collected, and the appearance of the capsules was examined under a microscope. No capsule destruction was observed. . As a result of testing the handwriting for thermal discoloration, 1
It had a purple color at 4 ° C. or lower and a fluorescent pink at 32 ° C. or higher, and exhibited the same color change property as the color change property of the capsule slurry used as a raw material for ink formation also in the hysteresis characteristic between both temperatures.

Example 7 2- (2-chloroanilino) -6-dibutylfluorane 3 parts, 1,1-hexylidenebisphenol 8 parts, n-butyl stearate 30 parts, n-butyl palmitate 2
A thermochromic composition consisting of 0 part, 2 parts of Tinuvin 328 (made by Ciba-Geigy, an ultraviolet absorber), 20 parts of a phenol novolac-based epoxy resin, and 50 parts of a cosolvent were added to 70 ° C.
The inclusion solution that was heated and dissolved in 1. was emulsified and dispersed in an aqueous protective colloid resin medium with a homomixer. The particle size at the time of emulsification was set while adjusting the rotation speed of the homomixer so that the average particle size was 10 μm. Then, a water-soluble diamine compound was added as a curing agent, and stirring was continued at 90 ° C. for 8 hours to complete encapsulation. After the reaction, the capsule dispersion liquid was diluted with twice the amount of water, and then filtered through a 625-mesh stainless mesh, and 105 g of microcapsules was isolated as a water-containing cake by centrifugation. The cake had a water content of 38%.

The particle size distribution of the microcapsules was measured by the same method as in Example 1. The above is a cumulative total of 97 when 0.5 μm ≦ D ≦ 20 μm.
%, And the average volume average particle diameter was 12 μm.

When the obtained microcapsules were observed with a microscope, it was confirmed that they were hemispherical flat capsules having recesses.

Thermochromic properties of the microcapsule pigment were black at 12 ° C or lower and colorless at 17 ° C or higher. A transition region of discoloration was shown between both temperatures. Using the obtained microcapsule pigment, a ballpoint pen was prepared with the same ink formulation and ballpoint pen specifications as in Example 1. When I wrote it down on the report paper, good ink ejection was observed from the start of writing, and the handwriting density was also reasonable. As a result of continuously writing the circular loop, it was possible to consume all the filled ink. After leaving the handwriting in a constant temperature bath at 50 ° C. for 10 days, its discoloration property was examined. As a result, the thermochromic property is 1
It was black at 2 ° C or lower and colorless at 17 ° C, and there was no deterioration in the discoloration function of the handwriting including the transitional region of discoloration.

Comparative Example 1 A ballpoint pen was manufactured in the same procedure as in Example 1 except that the average particle size at the time of emulsification was set to 15 μm for microcapsulation in order to change only the particle distribution of Comparative Example 1. did. The particle size distribution of the obtained microcapsule slurry was as follows. The above is a cumulative total of 81 when 0.5 μm ≦ D ≦ 20 μm.
%, And the average particle size was 16 μm.

When a writing test was conducted, the ink was faint from the start of writing, and after a while, the ink started to be ejected, but the density was extremely thin and the handwriting density was somewhat unsatisfactory. When 0.1 g of ink was consumed, it became faint, so when the ballpoint pen was disassembled and the ink in the ball storage part, especially the ink near the ball was observed with a microscope, mononuclear particles of 25-30 μm but large particles were dense. Was there.

Comparative Example 2 Using the same microcapsule slurry as in Example 1,
The amount of shear thinning resin in the ink formulation was increased. The ballpoint pen specification was manufactured in the same manner as in Example 1. An example of ink formulation is shown below. [Parts by weight] Microcapsule slurry 44.00 (solid content 27.3%) Xanthan gum 0.60 Water 32.59 Urea 11.00 Glycerin 11.00 Nopco SW-WET-366 0.55 Nopco 8034 0.13 Proxel XL -0.13 ───────────────────────── 100.00

When a writing test was performed using the thermochromic water-based ballpoint pen obtained as described above, no ink was ejected from the beginning of writing, and no change occurred even if writing was continued for a while. When the ink viscosity was measured, the viscosity was high as shown in the table below, which is considered to be due to the insufficient reduction of the viscosity at the time of shear peculiar to the aqueous ball.

The solid content of the thermochromic pigments in Examples 1 to 6 and Comparative Examples 1 and 2, the average particle diameter, the ink viscosity, the shear thinning viscosity, the ball diameter, the clearance and the evaluation in the writing test are shown in the table.

[Table 1]

[0062]

INDUSTRIAL APPLICABILITY The present invention is a shear-thinning thermochromic ink in which a thermochromic microcapsule pigment is dispersed and a ballpoint pen using the same, which satisfies a smooth writing feeling.
It is possible to provide a uniform and stable thermochromic handwriting continuously and provide a new and convenient writing material. A solid writing material in which a thermochromic microcapsule pigment is dispersed in an excipient such as wax has been conventionally disclosed as an application of the thermochromic material to a writing material. The width of handwriting cannot be formed continuously, the writing feeling is not smooth, and even if it has applicability in the field of art materials, it is not practical as a writing instrument.

The ballpoint pen of the present invention has practical utility in various fields. Specifically, the application of the water-based thermochromic ballpoint pen of the present invention will be illustrated. (1) Write a secret message or pattern on a New Year's card, Christmas card, greeting card, etc. with a thermochromic ball-point pen, or combine various ball-point pens and printed patterns so that the pattern will change. Can be created. (2) Similarly, when creating a confidential memo, it is possible to fill in with the ballpoint pen of the present invention. Discoloration point 10 ℃
If a thermochromic material that develops color only upon cooling is applied, it will be in a decolored state at room temperature, so that even if it is lost, there is an advantage that the description cannot be read by a third party. (3) The thermochromic water-based ballpoint pen of the present invention exhibits a particular effect when used for learning. That is, for example, if you use a ballpoint pen that has a large hysteresis characteristic for discoloration for questions, tests, drills, English translation,
Once you have filled in the answers and supplementary items in the colored state of the thermochromic ink and learned, then if you want to review again or check the memory, once erase all the items by applying heat. Then, in the completely reset state,
You can work on the problem again. Since this operation can be repeated any number of times, it has an advantage as a writing instrument for learning field as a useful material that has never existed before. (4) It can also be used as a normal writing instrument.
That is, if a thermochromic ink having a discoloring temperature that maintains a colored state at room temperature, for example, a 33 ° C discoloring ink is used, it can be written like a general writing instrument, and the colorful color change of the handwriting can be enjoyed. You can also In such a case, in addition to those that change from color to colorless, by using dichroic change that changes from color to color, or by using thermochromic capsules of different colors with different discoloration temperatures, you can blow it or warm it by hand. By doing so, it is possible to enjoy a variety of color changes according to temperature changes.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of the outer shape of an example of a microcapsule pigment. (A) shows an external appearance, and (B) shows a cross-sectional state.

FIG. 2 is a schematic explanatory view of the outer shape of another example of the microcapsule pigment. (A) shows the appearance and (B) shows the cross-sectional state.

FIG. 3 is a schematic explanatory view of the outer shape of another example of a microcapsule pigment. (A) shows the appearance and (B) shows the cross-sectional state.

FIG. 4 is a schematic explanatory view of the outer shape of another example of a microcapsule pigment. (A) shows the appearance and (B) shows the cross-sectional state.

FIG. 5 is a schematic explanatory view of the outer shape of another example of the microcapsule pigment. (A) shows the appearance and (B) shows the cross-sectional state.

FIG. 6 is a vertical cross-sectional explanatory view of an embodiment of the tip portion of the ballpoint pen of the present invention.

FIG. 7 is a sectional view taken along line XX of FIG. 6;

FIG. 8 is an explanatory longitudinal sectional view of another example of the tip portion of the ballpoint pen of the present invention.

9 is a sectional view taken along line XX of FIG.

FIG. 10 is an explanatory longitudinal sectional view of another example of the tip portion of the ballpoint pen of the present invention.

FIG. 11 is a vertical cross-sectional explanatory view of an embodiment of the ball-point pen of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ball-point pen 2 Ball 3 Ball accommodating part 31 Center hole 32 Outlet groove 33 Ball receiving seat 4 Ink accommodating part 5 Microcapsule pigment 51 Wall film 52 Dimple 53 Thermochromic composition 6 Thermochromic water-based ballpoint ink 7 Ink follower A Internal diameter B outer diameter C space

Claims (9)

[Claims] 1. An aqueous medium containing (a) a thermochromic microcapsule pigment, (b) a shear thinning substance, water and a water-soluble organic solvent as essential components, wherein the microcapsule pigment is dispersed in the aqueous medium. Thermochromic water-based ballpoint pen ink in a state. 2. A thermochromic microcapsule pigment is obtained by coating a wall film with a homogenous solution containing an electron-donating organic compound, an electron-accepting compound and a reaction medium for controlling the color change temperature as essential components. Is a pigment occupying 95% by volume or more in the range of 0.5 μm to 20 μm. 3. The thermochromic water-based ballpoint pen ink according to claim 1, wherein the thermochromic microcapsule pigment is a pigment composed of a wall film formed by an interfacial polymerization or interfacial polycondensation method having a depression on at least a part of its outer surface. . 4. The particle distribution is within the range of 0.5 to 20 μm.
Thermochromic microcapsule pigment occupying 5% by volume or more 1
5 to 45 wt% (solid content), shear thinning resin 0.1
0.5% by weight, containing 5 to 35% by weight of water-soluble organic solvent,
The balance is water, and the viscosity is 40 to 160 m. Pa. s
The thermochromic water-based ballpoint pen ink according to any one of claims 1 to 3, which is in a range of (value at a rotation speed of 100 rpm in an EM type rotational viscometer) and satisfies a shear thinning viscosity index of 0.1 to 0.6. 5. A ball-point pen having a tip that rotatably holds a ball so that the ink contained in the ink containing portion can be drawn out for writing, and (a) the thermochromic microcapsule is contained in the ink containing portion. A pigment, (b) an aqueous medium containing a shear thinning substance, water and a water-soluble organic solvent, wherein the microcapsule pigment is filled with a thermochromic aqueous ball-point pen ink in a dispersed state. And a ballpoint pen. 6. The ball-point pen according to claim 5, wherein the ink follower is arranged in contact with the rear end of the thermochromic ball-point pen ink in the ink storage portion. 7. The ball-point pen according to claim 5, wherein the difference between the inner diameter of the ball housing portion that rotatably holds the ball and the outer diameter of the ball is 10 to 60 μm. 8. The difference between the inner diameter of the ball accommodating portion that rotatably holds the ball and the outer diameter of the ball is 10 to 60 μm,
7. The ball-point pen according to claim 5, wherein the ball is provided with a space capable of moving in the axial direction by 20 to 100 μm. 9. The thermochromic water-based ballpoint pen ink comprises 15 to 45% by weight of thermochromic microcapsule pigment (solid content), which accounts for 95% by volume in a particle distribution of 0.5 to 20 μm, and a shear thinning resin. 1 to 0.5% by weight, a water-soluble organic solvent 5 to 35% by weight, and the balance being water, and the viscosity is 40 to 160 m.p. Pa. s (value at 100 rpm of EM type rotational viscometer),
The water-based ballpoint pen according to claim 5, which satisfies a shear thinning index of 0.1 to 0.6.