JP2018053182A - Water-based ink composition for writing instrument and writing instrument using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based ink composition for writing instrument which suppresses settlement of a pigment in an ink composition for writing instrument, and can suppress the settlement when using ink for writing instrument having low viscosity, and to provide a writing instrument using the same.SOLUTION: There are provided a water-based ink composition for writing instrument which contains water, a pigment and a biomass nanofiber and has specific ink viscosity; and a writing instrument using the same.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a water-based ink composition for writing instruments. More specifically, the present invention relates to a water-based ink composition for a writing instrument containing a pigment and biomass nanofibers, and a writing instrument using the same.

  Conventionally, an ink composition for a writing instrument using a thermochromic microcapsule pigment in which a reversible thermochromic composition is encapsulated in a microcapsule is known as a pigment. Writing instruments using these inks for ballpoint pens or markers are known, but the microcapsule pigment may settle or float due to the difference in specific gravity between the microcapsule pigment and the vehicle in which it is dispersed. Therefore, in order to stably disperse the microcapsule pigment, a loose bridging structure is prepared by blending a shear thinning agent such as a so-called gelling agent (for example, Patent Document 1) or using a polymer flocculant. And improving the redispersibility of the microcapsule pigment (for example, Patent Document 2) to obtain an ink composition. However, the ink composition has a high apparent viscosity and is difficult to use for a writing instrument having an ink supply mechanism using a comb groove using a low-viscosity ink typified by a fountain pen. There were problems such as the handwriting being smeared and the ink not being able to be supplied to the writing tip.

  On the other hand, the use of biomass nanofibers as industrial products has been studied. Biomass nanofibers are those in which cellulose, chitin, and chitosan are uniformly formed into nanofibers at the nano level, and their use in aqueous emulsion compositions has been studied (for example, Patent Document 3). Moreover, using the modified cellulose nanofiber which has a complicated structure for a water-based ink composition is performed (for example, patent document 4 etc.). Patent Document 4 describes that a specific modified cellulose fiber having a complicated structure is used in a water-based ink composition and a writing instrument. However, the ink viscosity is several tens of mPa · s or more, and a comb groove is used. As with the above ink composition, the ink viscosity is high, the ink may be blurred, or the ink may not be supplied. I was not satisfied.

JP 2014-189686 A JP, 2015-10124, A JP-A-10-95922 JP 2013-181167 A

  The present invention suppresses the sedimentation of the pigment in the ink composition for writing instruments, can suppress the sedimentation even when used in a low-viscosity ink for writing instruments, and does not blur the handwriting when writing. A water-based ink composition for a writing instrument and a writing instrument using the same are provided.

In the present invention, the above-mentioned problems have been solved by blending biomass nanofibers in the ink composition for writing instruments to obtain a specific ink viscosity.
That is, the present invention
“1. A water-based ink composition for a writing instrument comprising a pigment, water, and biomass nanofibers, and having a viscosity measured at 30 rpm using a BL-type viscometer at 20 ° C. of 1 to 20 mPa · s. .
2. 2. The water-based ink composition for a writing instrument according to item 1, wherein the pigment is a microcapsule pigment containing a functional material.
3. The functional material is
(A) a component comprising an electron-donating color-forming organic compound;
(B) a component comprising an electron-accepting compound;
(C) a reaction medium for reversibly causing an electron transfer reaction by the component (a) and the component (b) in a specific temperature range;
The water-based ink composition for a writing instrument as described in item 2, wherein the composition is a reversible thermochromic composition.
4). The water-based ink for a writing instrument according to any one of Items 1 to 3, wherein the biomass nanofiber is one or more selected from cellulose nanofiber, chitin nanofiber, and chitosan nanofiber. Composition.
5. A writing instrument comprising the water-based ink composition for a writing instrument according to any one of items 1 to 4.
6). The writing instrument according to claim 5, wherein the writing instrument is a writing instrument including an ink flow rate adjusting mechanism using comb grooves. ".

  According to the present invention, by using biomass nanofibers in the water-based ink composition for writing instruments, it is possible to suppress sedimentation of the pigment even when used in low-viscosity ink, and the storage stability of the ink composition is improved. It has excellent effects such as improvement.

It is explanatory drawing which shows the discoloration behavior of the microcapsule pigment which included the heat decoloring type reversible thermochromic composition. It is explanatory drawing which shows the discoloration behavior of the microcapsule pigment which included the heat decoloring type reversible thermochromic composition which has color memory property. It is explanatory drawing which shows the discoloration behavior of the microcapsule pigment which included the heating coloring type reversible thermochromic composition.

  Hereinafter, embodiments of the present invention will be described in detail. In the present specification, “part”, “%”, “ratio” and the like indicating the composition are based on mass unless otherwise specified.

  The ink composition for a writing instrument according to the present invention is characterized by using biomass nanofibers. Biomass nanofibers according to the present invention are cellulose, chitin, and chitosan uniformly refined at the nano level, and are physically processed without using chemical treatment using water and raw materials. Biomass nanofibers used in the present invention are fibers having a large aspect ratio with a fiber diameter of 1 to 100 nm and an aspect ratio of 100 or more. As a measuring method of a fiber diameter, it can measure with an electron micrograph.

  In the water-based ink composition for a writing instrument according to the present invention, biomass nanofibers are uniformly dispersed in the ink composition. It is considered that the biomass nanofibers are maintained in a uniformly dispersed state as a result of bonding of the functional groups of the nanofibers and water molecules. And when making a uniformly dispersed state, since it is dispersed in a state where the thermochromic microcapsule pigment is incorporated in the mesh, it is possible to suppress the aggregation of the microcapsule pigments, and to suppress the sedimentation, the dispersed state Is considered to be stable.

  The aqueous ink composition for writing according to the present invention comprises biomass nanofibers, and the biomass nanofibers are not particularly limited as long as they can be uniformly dispersed in the ink composition. Specifically, commercially available biomass nanofibers or biomass nanofibers described in JP 2011-56456 A, International Publication 2010/073758, and the like can be used. In addition, as commercially available biomass nanofibers, “BiNFi-s” series, BiNFi-sIMa-10002, BiNFi-sBMa-120002, BiNFi-sWMa-1202, BiNFi-sAMa-10002, BiNFi-sFMa- manufactured by Sugino Machine Co., Ltd. 10002 (all product names, cellulose nanofibers), BiNFi-sSFo-20002 (product name, chitin nanofibers), BiNFi-sEFo-08002 (product name, chitosan nanofibers), “Cerish” series manufactured by Daicel Finechem, KY100S, KY100G, KY110N (all product names, cellulose nanofibers) and the like can be used.

  The aspect ratio of the biomass nanofiber used in the present invention is 100 or more, but the aspect ratio is preferably 1000 or less, and more preferably 300 or less. The aspect ratio is determined by the ratio between the fiber diameter and the fiber length, but if the fiber length is large, the ink viscosity tends to increase, and the target low-viscosity ink composition may not be obtained. It is preferable that it is the said range.

  The blending ratio of the biomass nanofiber is preferably 0.05 to 0.5% by mass, more preferably 0.1 to 0.3% by mass with respect to the total mass of the ink composition. More preferably, it is 0.15-0.25 mass%. If the amount is less than the above range, the effect of maintaining the dispersion in a stable state of the microcapsule pigment by the biomass nanofibers may not be sufficiently exhibited.If the amount is more than the above range, the ink viscosity tends to increase, and the aim is The resulting low viscosity ink composition may not be obtained. It is considered that the above range is preferable because the microcapsule pigment can stably maintain a dispersion by the mechanism, and an ink having a target viscosity can be obtained.

  The biomass nanofibers used in the present invention may be blended directly into the ink composition or may be blended as a dispersion.

  In the present invention, pigments that are usually used in ink for writing instruments and the like can be used as pigments. For example, in addition to organic pigments, plastic pigments, and inorganic pigments that are usually used for writing instrument inks, metallic pigments with metallic luster, colored metal powder pigments, metal deposited powder pigments, glass flakes, and colors such as iris colors Non-discoloring pigments such as pearl pigments, liquid crystals, reversible thermochromic compositions, microcapsule pigments encapsulating functional materials such as photochromic materials, and the like can be used.

  Specific examples of organic pigments include Hansa Yellow, Benzidine Yellow, Permanent Red, Lake Red, Victoria Blue Lake, Phthalocyanine Blue, Phthalocyanine Green, and Aniline Black.

  When using plastic pigments that can select white or colorful pigments with a relatively low specific gravity that can easily prevent sedimentation in the ink composition, some processed pigments have a low specific gravity. When a pigment is used, it is possible to increase the blending amount of the pigment itself, to obtain an ink composition with higher dispersion stability, and even when used in combination with a pigment whose specific gravity is lightened by processing. Very effective. Examples of plastic pigments include Ropeke OP-62, OP-84J, OP-91, and HP1055 (above, manufactured by Rohm and Haas), Epocolor FP-1000N, FP-112, and FP-113. FP-114, FP-115, FP-116, FP-117, FP-101, FP-101, MA-1002FW, FP-1050 (above, manufactured by Asahi Chemical Co., Ltd.), Lumicol NKP-8604, The same NKP-8605, the same NKP-8607, the same NKP-9203, the same NKP-9207, the same NKP-9237, the same NKP-9238 (manufactured by Nippon Fluorescent Chemical Co., Ltd.) and the like. Further, not only the processed pigment but also the pigment having a low specific gravity can improve the dispersion stability.

  Examples of inorganic pigments include carbon black, ultramarine, kaolin, and various types of titanium oxide such as rutile and anatase types. Commercially available titanium oxides include Tytone SR-1, R-650, R-3L, A-110, A-150 (above, manufactured by Sakai Chemical Industry Co., Ltd.), Typek R-580, R-550, R-780 (above, manufactured by Ishihara Sangyo Co., Ltd.), Kronos KR-310, KR-380, KR-480, KA-10, KA-15 (above, Titanium Industry ( Co., Ltd.), Taipur R-900, R-931, R-960 (above, manufactured by DuPont Japan Limited), Titanic JR-301, JR-600A, JR-603, JA -4 (manufactured by Teika Co., Ltd.). In addition, LIOFAST WHITE H201, EM WHITE H, EM WHITE FX9048 (manufactured by Toyo Ink Co., Ltd.), Pollux White PC-CR (manufactured by Sumitomo Color Co., Ltd.), FUJI SP WHITE 11, 1011, 1036, It is preferable to use a commercially available titanium oxide aqueous dispersion such as 1051 (manufactured by Fuji Pigment Co., Ltd.) because the dispersion step in production can be omitted and ink can be easily formed.

  Titanium oxide is one of pigments having a high specific gravity among various pigments. However, by incorporating the titanium oxide nanotubes used in the present invention, a certain degree of dispersion stability can be obtained even in a low viscosity ink.

  As the metal powder pigment, metal powder pigments having a metallic luster such as aluminum powder, brass powder, stainless steel powder, bronze powder may be used as they are, or metal pigments in which a colorant is adsorbed to these metal powder pigments may be used. . In addition, the metal powder pigment such as aluminum powder may be processed and dispersed in advance with a surfactant, resin, solvent, etc. to form a paste-like pigment dispersion or liquid metal pigment dispersion, Further, the metal powder pigment such as aluminum powder is processed with wax, surfactant, resin or the like, but may be a solid metal pigment containing no solvent.

  Examples of the aluminum paste include WXM0630, WB0230, 400SW, FM4010WG (above, manufactured by Toyo Aluminum Co., Ltd.), and examples of the colored aluminum pigment include F503RG, F503BG, F500SI, F500RE, F500RE, F500BL (above, Toyo Aluminum Co., Ltd.) Etc.) and solid-state RotosafeAqua 250 042, 250 022, 260 003, etc. (above, manufactured by ECKART Co., Ltd.).

  Examples of the aluminum powder include AA12, AA8, No. 900, no. 18000 (manufactured by Fukuda Metal Foil Powder Co., Ltd.).

  As metal-deposited powder pigments, Elgi Silver # 500, # 325, # 200 (above, Oike Kogyo Co., Ltd.) obtained by vacuum-depositing aluminum on a synthetic resin and protecting the metal layer with the resin and pulverizing it into pieces. Etc.). In addition, L.G. Gold # 500, ibid. Gold # 500, ibid. Gold # 325, ibid. Gold # 325, Red # 325, Blue # 325, Green # 325, Violet # 325, Black # 325, Copper # 325, R.P. Gold # 200, B.D. Gold # 200, Red # 200, Blue # 200, Green # 200, Violet # 200, Black # 200, Copper # 200 (above, manufactured by Oike Kogyo Co., Ltd.).

  As the glass flake pigment, metashine REFSX-2015PS, -2025PS, -2040PS, RCFSX-5030NS, -5030NB, -5030PS, -5015PS, 5090GG (Nippon Sheet Glass Co., Ltd.) etc. are mentioned.

  Examples of pearl pigments include Iriodin 120 Luster Satin, 123 Bright Luster Satin, 201 Rutile Fine Gold, 211 Rutine Fine Red, 221 Rutine Fine Blue, 223 Rutine Fine G, 223 Rutine Fine L 323 Royal Gold Satin, 520 Bronze Satin, 522 Red Brown Satin, 524 Red Satin (manufactured by Merck Japan Ltd.).

  Furthermore, as the pigment according to the present invention, a microcapsule pigment containing a functional material can be used, but it is preferable because handwriting with various functions can be obtained. Examples of the functional material include liquid crystals such as cholesteric liquid crystal and nematic liquid crystal, reversible thermochromic composition, and photochromic material.

  Examples of the liquid crystal include Helicon HC SLM 90020, 90120, 90220, 90320 (above, manufactured by Wacker Chemie).

  The reversible thermochromic microcapsule pigment that can be used in the present invention will be described below. Examples of the reversible thermochromic microcapsule pigment include a predetermined temperature (discoloration point) described in JP-B-51-44706, JP-B-51-44707, JP-B-1-29398, and the like. Before and after the color change, the color disappears in the temperature range above the high temperature side discoloration point, and the color develops in the temperature range below the low temperature side discoloration point. The other state is maintained while the heat or cold required to develop the state is applied, but when the heat or cold is no longer applied, the hysteresis width returns to the state exhibited in the normal temperature range. Applying a reversible thermochromic microcapsule pigment containing a reversible thermochromic composition that has a relatively small characteristic (ΔH = 1 to 7 ° C.) (decolored by heating and develops color by cooling) (Fig. 1 Irradiation).

In addition, large hysteresis characteristics (ΔH _B = 8 to 50 ° C.) described in JP- _B -4-17154, JP-A-7-179777, JP-A-7-33997, JP-A-8-39936, and the like. ), That is, when the shape of the curve plotting the change in the color density due to the temperature change is lowering the temperature from the lower temperature side than the color changing temperature range, as opposed to increasing the temperature from the lower temperature side. In the specific temperature range, the color changes in a low temperature range below the complete color development temperature (t ₁ ) or the color erase state in the high temperature range above the complete color erase temperature (t ₄ ). A reversible thermochromic composition having a color memory property in a temperature range between t _{2 and} t ₃ (substantially two-phase holding temperature range) (decolored by heating and developed by cooling). Reversible thermochromic micro Capsule pigments can also be applied (see FIG. 2).

  The hysteresis characteristics in the color density-temperature curve of the microcapsule pigment encapsulating the reversible thermochromic composition will be described below with reference to the graph of FIG.

In FIG. 2, the vertical axis represents color density and the horizontal axis represents temperature. The change in color density due to the temperature change proceeds along the arrow. Here, A is a point indicating a density at a temperature t ₄ (hereinafter referred to as a complete decoloring temperature) reaching a completely decolored state, and B is a temperature t ₃ (hereinafter referred to as a decoloring start temperature) at which decoloring starts. C is a point indicating a density at a temperature t ₂ at which color development starts (hereinafter referred to as a color development start temperature), and D is a temperature t ₁ at which a fully colored state is reached (hereinafter referred to as a color development start temperature). , Referred to as a complete color development temperature).

  The length of the line segment EF is a scale indicating the discoloration contrast, and the length of the line segment HG is a temperature width indicating the degree of hysteresis (hereinafter referred to as hysteresis width ΔH). It is easy to maintain each state before and after the color change.

Here, the difference between t ₄ and t ₃ , or the difference between t ₂ and t ₁ (Δt) is a scale indicating the sensitivity of discoloration.

Further, only one specific state (coloring state) exists in the room temperature range among the color development and decoloring states of the reversible thermochromic composition, and the handwriting by the reversible thermochromic composition is easily caused by frictional heat generated by friction. In order to change color (discolor), it is preferable that the complete color erasing temperature (t ₄ ) is 50 to 95 ° C. and the color development start temperature (t ₂ ) is −50 to 10 ° C.

Here, the color development state can be maintained in a normal temperature range, and in order to facilitate the discoloration due to the friction of the handwriting, the complete color erasing temperature (t ₄ ) is 50 to 95 ° C., and the color development start temperature (t ₂ ). When the heating is stopped without reaching the complete decoloring temperature (t ₄ ) from the color developing state through the decoloring start temperature (t ₃ ), the first state again The state in which color development occurs is maintained even if the cooling is stopped in a state where the phenomenon does not reach the complete color development temperature (t ₁ ) through the color development start temperature (t ₂ ) from the decolored state. Therefore, if the complete color erasing temperature (t ₄ ) is 50 ° C. or more exceeding the normal temperature range, the color development state is maintained in the normal use state, and the color development start temperature (t ₂ ) is below the normal temperature range. If the temperature is −50 to 10 ° C., the decolored state is maintained in normal use. Is done.

In the temperature setting of the complete color erasing temperature (t ₄ ), a higher temperature is preferable in order to maintain the color development state in a normal use state, and the frictional heat due to friction is a complete color erasure temperature ( In order to exceed t ₄ ), a low temperature is preferred. Therefore, the complete decoloring temperature (t ₄ ) is preferably 50 to 90 ° C., more preferably 60 to 80 ° C. Further, in the temperature setting of the color development start temperature (t ₂ ) described above, it is preferably a lower temperature in order to maintain the decolored state in a normal use state, and −50 to 5 ° C. is preferable. -50-0 degreeC is more suitable. In the present invention, the hysteresis width (ΔH) is in the range of 50 ° C. to 100 ° C., preferably 55 to 90 ° C., more preferably 60 to 80 ° C.

As the microcapsule pigment that can be used in the aqueous ink composition for writing according to the present invention, a reversible thermochromic composition having a complete decoloring temperature (t ₄ ) on the higher temperature side than the above-mentioned color changing temperature range can also be used.

While only one specific state (coloring state) is present in the normal temperature range among the color development and decoloring states of the reversible thermochromic composition, the handwriting by the reversible thermochromic composition is generated by heat obtained from a heating eraser or the like. In order to erase the color, the complete color erasing temperature (t ₄ ) is 80 ° C. or higher and the color development start temperature (t ₂ ) is 15 ° C. or lower. Here, the color development state can be maintained in a normal temperature range, and the color erasure state is maintained in normal use. Therefore, the complete color erasure temperature (t ₄ ) is 80 ° C. or more and the color development start temperature (t ₂ ). If the heating is stopped in a state where the color disappearance temperature does not reach the complete color erasing temperature (t ₄ ) from the color developing state through the color erasing start temperature (t ₃ ), the state returns to the first state again. And the state in which color development is maintained even if the cooling is stopped in a state where the color development start temperature (t ₂ ) has not reached the complete color development temperature (t ₁ ) from the decolored state. When the complete color erasing temperature (t ₄ ) is 80 ° C. or more exceeding the normal temperature range, the color development state is maintained in a high temperature environment such as a car in summer and the color development start temperature (t ₂ ) is 15 ° C. below the normal temperature range. The decolored state is maintained in normal use at the following temperatures. Further, if the complete color erasing temperature (t ₄ ) is 90 ° C. or higher, the color development state is more maintained in a high temperature environment, and if the color development start temperature (t ₂ ) is 10 ° C. or lower, the color erasure state is normal. More maintained in use. Accordingly, the temperature setting is an important requirement for selectively displaying a discolored image on the image surface to be viewed, and the image can achieve the intended purpose. In the above-described temperature setting of the complete color erasing temperature (t ₄ ), it is preferable that the color development state be higher in order to be maintained in a high temperature environment, and the complete color erasing temperature (t ₄ ) is preferably 90 °. More than 100 degreeC, More preferably, it is 100 degreeC or more. Furthermore, in the temperature setting of the color development start temperature (t ₂ ) described above, it is preferably a lower temperature in order to maintain the decolored state in a normal use state, and −50 to 10 ° C. is preferable. -50-5 degreeC is more suitable. In order to bring the reversible thermochromic composition into a colored state in advance, it is preferable to cool in a general-purpose freezer as a cooling means, but considering the cooling capacity of the freezer, the limit is up to −50 ° C., Accordingly, the complete color development temperature (t ₁ ) is −50 ° C. or higher. In the present invention, the hysteresis width (ΔH) is in the range of 70 ° C to 150 ° C.

  By using the reversible thermochromic composition, the handwriting formed on important documents and the like is not discolored even if left in a high temperature environment such as in a car in the summer, and is applicable as a water-based ink composition for writing instruments. Can be spread. Furthermore, since it becomes difficult to erase by rubbing with the friction member, it can be used to determine the authenticity of the document.

  Hereinafter, the components (a), (b) and (c) constituting the reversible thermochromic composition will be described.

  In the present invention, the component (a) is an electron-donating colorant that develops color by donating electrons to the component (b), which is a developer, and opening a ring structure such as a lactone ring of the component (a). It consists of an organic compound. Examples of such electron-donating color-forming organic compounds include diphenylmethane phthalides, phenyl indolyl phthalides, indolyl phthalides, diphenyl methane azaphthalides, phenyl indolyl azaphthalides, fluorans, styrinoquinolines. , Diazarhodamine lactones, pyridines, quinazolines, bisquinazolines and the like.

  As the electron-accepting compound of component (b), a group of compounds having active protons, a group of pseudo-acidic compounds (a group of compounds that are not acids but act as an acid in the composition and cause component (a) to develop color), electrons There is a group of compounds having pores.

  Examples of compounds having active protons include monophenols to polyphenols as compounds having phenolic hydroxyl groups, and alkyl groups, aryl groups, acyl groups, alkoxycarbonyl groups, carboxy groups and esters thereof as substituents. Alternatively, those having an amide group, a halogen group, etc., and bis-type and tris-type phenols, phenol-aldehyde condensation resins and the like can be mentioned. Moreover, the metal salt of the compound which has the said phenolic hydroxyl group may be sufficient.

  Examples of the (c) component of the reaction medium that causes the electron transfer reaction by the (a) component and the (b) component to occur reversibly in a specific temperature range include alcohols, esters, ketones, and ethers. .

  The component (c) is preferably a large hysteresis characteristic regarding the color density-temperature curve (a curve plotting a change in color density due to a temperature change changes the temperature from the low temperature side to the high temperature side and the high temperature side to the low temperature side). A carboxylic acid ester compound having a ΔT value (melting point-cloud point) of 5 ° C. or more and less than 50 ° C., which can form a reversible thermochromic composition exhibiting color memory properties, which changes color when changing to the side) Used. As such a compound, various compounds have been proposed and can be arbitrarily selected and used. Specific examples thereof include the following.

（式中、Ｒ１は水素原子又はメチル基を示し、ｍは０〜２の整数を示し、Ｘ１、Ｘ２のいずれか一方は−（ＣＨ２）ｎＯＣＯＲ２又は−（ＣＨ２）ｎＣＯＯＲ２、他方は水素原子を示し、ｎは０〜２の整数を示し、Ｒ２は炭素数４以上のアルキル基又はアルケニル基を示し、Ｙ１及びＹ２は水素原子、炭素数１〜４のアルキル基、メトキシ基、又は、ハロゲンを示し、ｒ及びｐは１〜３の整数を示す。） First, as the component (c), a compound represented by the following general formula (1) described in JP-A No. 2006-137886 is suitably used.

(In the formula, R1 represents a hydrogen atom or a methyl group, m represents an integer of 0 to 2, one of X1 and X2 represents — (CH2) nOCOR2 or — (CH2) nCOOR2, and the other represents a hydrogen atom. , N represents an integer of 0 to 2, R2 represents an alkyl group or alkenyl group having 4 or more carbon atoms, Y1 and Y2 represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen. , R and p represent an integer of 1 to 3)

Among the compounds represented by the formula (1), when R ₁ is a hydrogen atom, it is preferable because a reversible thermochromic composition having a wider hysteresis width can be obtained, and R ₁ is a hydrogen atom, and , M is more preferably 0.

（式中のＲは炭素数８以上のアルキル基又はアルケニル基を示すが、好ましくは炭素数１０〜２４のアルキル基、更に好ましくは炭素数１２〜２２のアルキル基である。） Of the compounds represented by the formula (1), a compound represented by the following general formula (2) is more preferably used.

(In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, more preferably an alkyl group having 12 to 22 carbon atoms.)

（式中、Ｒは炭素数８以上のアルキル基又はアルケニル基を示し、ｍ及びｎはそれぞれ１〜３の整数を示し、Ｘ及びＹはそれぞれ水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、ハロゲンを示す。） Furthermore, a compound represented by the following general formula (3) can also be used as the component (c).

(In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, m and n each represents an integer of 1 to 3, X and Y represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, carbon, respectively. (The alkoxy group of Formula 1-4 is shown, and a halogen.)

  Furthermore, a compound represented by the following general formula (4) can also be used as the component (c).

（式中、Ｘは水素原子、炭素数１〜４のアルキル基、メトキシ基、ハロゲン原子のいずれかを示し、ｍは１乃至３の整数を示し、ｎは１〜２０の整数を示す。） (I) an electron donating color-forming organic compound, (b) an electron accepting compound, (c) a reaction medium that reversibly causes an electron transfer reaction by the components (a) and (b) in a specific temperature range; A reversible thermochromic microcapsule pigment in which a reversible thermochromic composition comprising at least the above is encapsulated in microcapsules will be described below.

(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom, m represents an integer of 1 to 3, and n represents an integer of 1 to 20).

（式中、Ｒは炭素数１乃至２１のアルキル基又はアルケニル基を示し、ｎは１〜３の整数を示す。） Furthermore, a compound represented by the following general formula (5) can also be used as the component (c).

(In the formula, R represents an alkyl group or alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3).

（式中、Ｘは水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、ハロゲン原子のいずれかを示し、ｍは１〜３の整数を示し、ｎは１〜２０の整数を示す。） Furthermore, a compound represented by the following general formula (6) can also be used as the component (c).

(In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, m represents an integer of 1 to 3, and n represents 1 to 20) Indicates an integer.)

（式中、Ｒは炭素数４〜２２のアルキル基、シクロアルキルアルキル基、シクロアルキル基、炭素数４〜２２のアルケニル基のいずれかを示し、Ｘは水素原子、炭素数１〜４のアルキル基、炭素数１〜４のアルコキシ基、ハロゲン原子のいずれかを示し、ｎは０又は１を示す。） Furthermore, a compound represented by the following general formula (7) can also be used as the component (c).

(In the formula, R represents any of an alkyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, a cycloalkyl group, and an alkenyl group having 4 to 22 carbon atoms, and X represents a hydrogen atom and an alkyl having 1 to 4 carbon atoms. A group, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, and n represents 0 or 1.)

（式中、Ｒは炭素数３〜７のアルキル基を示し、Ｘは水素原子、メチル基、ハロゲン原子のいずれかを示し、Ｙは水素原子、メチル基のいずれかを示し、Ｚは水素原子、炭素数１〜４のアルキル基、炭素数１又は２のアルコキシ基、ハロゲン原子のいずれかを示す。） Furthermore, a compound represented by the following general formula (8) can also be used as the component (c).

(In the formula, R represents an alkyl group having 3 to 7 carbon atoms, X represents a hydrogen atom, a methyl group or a halogen atom, Y represents a hydrogen atom or a methyl group, and Z represents a hydrogen atom. Or an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a halogen atom.)

  Further, as the electron-accepting compound, a specific alkoxyphenol compound having a linear or side chain alkyl group having 3 to 18 carbon atoms can be used (Japanese Patent Laid-Open Nos. 11-129623 and 11-5973), Hydroxybenzoic acid esters (Japanese Patent Laid-Open No. 2001-105732), gallic acid esters and the like (Japanese Patent Publication No. 51-44706, Japanese Patent Laid-Open No. 2003-253149) are used. A microcapsule pigment containing a reversible thermochromic composition that is decolored by cooling) can also be applied (see FIG. 3).

  The proportions of the components (a), (b), and (c) depend on the concentration, color change temperature, color change form, and type of each component, but generally desired color change characteristics can be obtained. The component ratio is in the range of (b) component 1 to (b) component 0.1 to 50, preferably 0.5 to 20, (c) component 1 to 800, preferably 5 to 200 (see above). All percentages are based on mass). Moreover, you may use each component in mixture of 2 or more types, respectively.

  The reversible thermochromic composition is encapsulated in microcapsules and used as a reversible thermochromic microcapsule pigment. This is because the reversible thermochromic composition can be kept in the same composition under the various use conditions and can exhibit the same effects.

  Methods for microencapsulating the reversible thermochromic composition include interfacial polymerization, interfacial polycondensation, in situ polymerization, in-liquid curing coating, phase separation from aqueous solution, and phase separation from 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 use. Furthermore, a secondary resin film may be provided on the surface of the microcapsule according to the purpose to impart durability, or the surface characteristics may be modified for practical use.

  Here, the mass ratio of the reversible thermochromic composition to the microcapsule wall membrane satisfies the range of 7: 1 to 1: 1, preferably 6: 1 to 1: 1.

  The reversible thermochromic microcapsule pigment has an average particle size of 0.1 to 5 [mu] m, preferably 0.1 to 3 [mu] m, more preferably 0.5 to 3 [mu] m. When the average particle size exceeds 5 μm, the microcapsule pigment may lack dispersion stability, and when the average particle size is less than 0.1 μm, it is difficult to exhibit high density color development. The particle size is measured using a laser diffraction / scattering particle size distribution measuring device (manufactured by Horiba, Ltd .; LA-300), and the average particle size (median diameter) is calculated on the basis of the numerical value. To do.

  When the ratio of the reversible thermochromic composition to the wall film is larger than the above range, the thickness of the wall film becomes too thin, and the resistance to pressure and heat tends to decrease, and the ratio of the wall film to the reversible thermochromic composition When the value is larger than the above range, color density and sharpness during color development tend to be reduced.

  The reversible thermochromic microcapsule pigment includes antioxidants, ultraviolet absorbers, infrared absorbers, dissolution aids, antiseptic / antifungal agents, non-thermochromic dyes and pigments as long as they do not affect their functions. Various additives such as can be added.

Examples of the photochromic material include spirooxazine derivatives and spiropyran derivatives.
Spirooxazine derivatives include indolinospirobenzoxazine compounds such as 1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzo Oxazine], 6'-chloro-5-fluoro-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 3,3-dimethyl-1-ethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5,7-difluoro-1,3,3 -Trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5-cyano-3,3-dimethyl-1- (methoxycarbonyl) methylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 1'-methyldispiro [cyclohexane-1,3'-[3H] indole-2 '( 1'H), 3 "-[3H] pyrido [4,3-f] [1,4] benzoxazine], 1'-methyl-5'-nitrodispiro [cyclopentane-1,3 '-[3H]- Indole-2 '(1'H), 3 "-[3H] pyrido [4,3-f] [1,4] benzoxazine], 1,3,3,5'-tetramethylspiro [2H-indole- 2,3 ′-[3H] pyrido [4,3-f] [1,4] benzoxazine], 6′-fluoro-1′-methyldispiro [cyclohexane-1,3 ′-[3H] indole-2 ′ ( 1'H), 3 "-[3H] pyrido [4,3-f] [1,4 Benzoxazine], 1-benzyl-6′-chloro-3,3-dimethylspiro [2H-indole-2,3 ′-[3H] pyrido [4,3-f] [1,4] benzoxazine], 6'-methoxy-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5-chloro-1,3 , 3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5-bromo-1,3,3-trimethylspiro [2H- Indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5-iodo-1,3,3-trimethylspiro [2H-indole-2,3'-[ 3H] pyrido [4,3-f] [1,4] benzox Gin], 5-trifluoromethyl-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 3,3 -Diethyl-1-methylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 1,3,3,6'-tetramethylspiro [2H -Indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 6-chloro-1,3,3-trimethylspiro [2H-indole-2,3'- [3H] pyrido [4,3-f] [1,4] benzoxazine], 5'-fluoro-1'-methyldispiro [cyclohexane-1,3 '-[3H] indole-2'(1'H), 3 "-[3H] pyrido [4,3-f] [1,4 Benzoxazine], 5-cyano-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5-ethoxycarbonyl -1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 4', 6'-difluoro-1'- Methyl dispiro [cyclohexane-1,3 ′-[3H] indole-2 ′ (1′H), 3 ″-[3H] pyrido [4,3-f] [1,4] benzoxazine], 3,3-dimethyl -1- (methoxycarbonyl) methylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 3,3-dimethyl-1-phenylspiro [2H -Indole-2, '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 5-methoxy-1,3,3-trimethylspiro [2H-indole-2,3'-[3H] pyrido [4 , 3-f] [1,4] benzoxazine], 1,3,3,5-tetramethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4 Benzoxazine], 7'-chloro-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 1, 3,3,7'-tetramethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3-f] [1,4] benzoxazine], 7'-methoxy-1,3,3 -Trimethylspiro [2H-indole-2,3 '-[3H] pyrido [4,3- f] [1,4] benzoxazine], 1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 6 '-Chloro-5-fluoro-1,3,3-trimethylspiro [2H-indole-2,3'-[3H] pyrido [2,3-f] [1,4] benzoxazine], 5-chloro- 1,3-dimethyl-3-ethyl-5'-methoxyspiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 3,3-diethyl -1-methyl-5-nitrospiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 1', 6'-dimethylspiro [cyclohexane-1 , 3 '-[3H] indole-2'(1'H) 3 "-[3H] pyrido [2,3-f] [1,4] benzoxazine], 9"-bromo-1'-methoxycarbonylmethyl-5'-trifluoromethyldispiro [cyclopentane-1,3 '-[3H] -indole-2'[1'H], 3 "-[3H] pyrido [2,3-f] [1,4] benzoxazine], 1-benzyl-3,3-di-n Butyl-7'-ethyl-5-methoxyspiro [2H-indole-1,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 1'-n-butyl-6' -Iododispiro [cycloheptane-1,3 '-[3H] -indole-2'(1'H), 3 "-[3H] pyrido [2,3-f] [1,4] benzoxazine], 3, 3-Dimethyl-9'-iodo-1-naphthylspiro [2H-indole 2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 4'-cyano-1'-(2- (methoxycarbonyl) ethyl) dispiro [cyclohexane-1,3 ' -[3H] indole-2 '(1'H), 3 "-[3H] pyrido [2,3-f] [1,4] benzoxazine], 7-methoxycarbonyl-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 4-bromo-3,3-diethyl-9'-ethoxy-1- (2- Phenyl) ethylspiro [2H-indole-2,3 '-[2,3-f] [1,4] benzoxazine], 1'-methyldispiro [cyclohexane-1,3'-[3H] -indole-2 '( 1'H), 3 "-[3H] pyrido [2,3 -F] [1,4] benzoxazine], 6-fluoro-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] Benzoxazine], 5-ethyl-9-fluoro-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 1'-benzyl-6 "-iododispiro [cyclopentane-1,3 '-[3H] -indole-2'(1'H),3"-[3H] pyrido [2,3-f] [1,4 Benzoxazine], 5-ethoxy-1,3,3-trimethylspiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 1'- Methyl-5'-trichloromethyldispiro [cyclohexane- , 3 '-[3H] -indole-2'(1'H), 3 "-[3H] pyrido [2,3-f] [1,4] benzoxazine], 1,3-diethyl-3-methylspiro [2H-indole-2,3 '-[3H] pyrido [2,3-f] [1,4] benzoxazine], 1'-methoxycarbonylmethyldispiro [cyclohexane-1,3'-[3H]- Indole-2 '(1'H)-[3H] pyrido [2,3-f] [1,4] benzoxazine] and the like, indole and spirobenzoxazine indole and benzene ring halogen, methyl, ethyl, methylene Each substituent such as ethylene, hydroxyl group and the like can be exemplified.

Examples of indolinospironaphthoxazine compounds include 1,3,3-trimethyl-spiroindoline naphthoxazine, 1,3,3-trimethyl-5-chloro-spiroindoline naphthoxazine, 1,3,3-trimethyl-5- Bromo-spiroindoline naphthoxazine, 1,3,3,5-tetramethyl-spiroindoline naphthoxazine, 1,3,3-trimethyl-5-n-propyl-spiroindoline naphthoxazine, 1,3,3-trimethyl- 5-iso-butyl-spiroindoline naphthoxazine, 1,3,3-trimethyl-5-methoxy-spiroindoline naphthoxazine, 1,3,3-trimethyl-5-n-propoxy-spiroindoline naphthoxazine, 1,3 , 3-Trimethyl-5-cyano-spiroindori Naphthoxazine, 1-n-propyl-3,3-dimethyl-spiroindoline naphthoxazine, 1-iso-butyl-3,3-dimethyl-spiroindoline naphthoxazine, 1-n-octyl-3,3-dimethyl-spiro Indoline naphthoxazine, 1-n-octadecyl-3,3-dimethyl-spiroindoline naphthoxazine, sodium 1,3,3-trimethyl-8'-sulfonate-spiroindoline naphthoxazine,
1,3,3-trimethyl-9'-methoxyspiroindoline naphthoxazine, 1,3,3-trimethyl-8'-cyano-spirobenzoindoline naphthoxazine, 1,3,3-trimethyl-5-trifluoro-spiro Indoline naphthoxazine, 1- (4′-methylphenyl) -3,3-dimethyl-spiroindoline naphthoxazine, 1,3,3-trimethyl-6 ′-(2,3-dihydro-1-indolino) -spiroindoline Naphthoxazine, 1,3,3-trimethyl-6 '-(1-piperidinyl) -spiroindoline naphthoxazine, 1,3,3-trimethyl-6'-(1-morpholino) -spiroindoline naphthoxazine, 1-ethyl -3,3-dimethyl-6-trifluoromethyl-6 '-(1-morpholino) -spi Indoline naphthoxazine, 1,3,3-trimethyl-6-trifluoromethyl-6 '-(1-piperidinyl) -spiroindoline naphthoxazine, 1-benzyl-3,3-dimethyl-spiroindoline naphthoxazine, 1- ( 4-methoxybenzyl) -3,3-dimethyl-spiroindoline naphthoxazine, 1- (4-chlorobenzyl) -3,3-dimethyl-spiroindoline naphthoxazine, 1-ethyl-3,3-dimethyl-spiroindoline naphtho Oxazine, 1-isopropyl-3,3-dimethyl-spiroindoline naphthoxazine, 1- (2-phenoxyethyl) -3,3-dimethyl-spiroindoline naphthoxazine, 1,3-dimethyl-3-ethyl-spiroindoline naphtho Oxazine, 1,3,3-trimethyl Ru-9'-hydroxy-spiroindoline naphthoxazine, 1,3-dimethyl-3-ethyl-8'-hydroxy-spiroindoline naphthoxazine, 1,3,3,5-tetramethyl-9'-methoxy-spiroindoline Naphthoxazine, 1,3,3,5,6-pentamethyl-9'-methoxy-spiroindoline naphthoxazine, 1,3,3-trimethyl-4-trifluoromethyl-5'-methoxy-spiroindoline naphthoxazine, 1 , 3,3-trimethyl-5'-methoxy-6'-trifluoromethyl-spiroindoline naphthoxazine, 1,3,3-trimethyl-4-trifluoromethyl-9'-methoxy-spiroindoline naphthoxazine, 1, 3,5,6-tetramethyl-3-ethyl-spiroindoline naphtho Gin, 1,3,3,5,6-pentamethyl-spiroindoline naphthoxazine, 1-methyl-3,3-diphenyl-spiroindoline naphthoxazine, 1- (4-methoxybenzyl) -3,3-dimethyl-spiro Indoline Spiro, such as indoline naphthoxazine, 1- (3,5-dimethylbenzyl) -3,3-dimethyl-spiroindoline naphthoxazine, 1- (2-fluorobenzyl) -3,3-dimethyl-spiroindoline naphthoxazine Examples of naphthoxazine indole and benzene ring halogens such as halogen, methyl, ethyl, methylene, ethylene, and hydroxyl groups.

  Examples of naphthopyran compounds include 3,3,9,9-tetraphenyl-3H, 9H-naphtho [2,1-b: 6,5-b ′]-dipyran, 3,3,10,10-tetraphenyl- 3H, 10H-naphtho [2,1-b: 7,8-b ′] dipyran, 3,3,9,9-tetraphenyl-3H, 10H-naphtho [4,3-b: 8,7-b] -Dipyran, 3,3-diphenyl-9-methoxy-3H-naphtho [4,3-b] pyran, 3,3-diphenyl-10-methyl-3H-naphtho [2,1-b: 5,6-b Dipyran-8-one, 3,3,9,9-tetra (4′-methoxy-phenyl) -3H, 9H-naphtho [2,1-b: 6,5-b ′]-dipyran, 3,3 -Diphenyl-8- (2- (4-dimethylamino) phenyl) ethene-3H-naphtho [4,3- ] Pyran, 3,3-diphenyl-5-acetoxy-3H-naphtho [4,3-b] pyran, 3,3-diphenyl-8- (1H-benzotriazol-1-yl) carbonyl-3H-naphtho [4] , 3-b] pyran.

  Examples of indolinospirophenanthrooxazine compounds include 1,3,3-trimethyl-spiroindoline phenanthrooxazine, 1,3,3-trimethyl-5-chloro-spiroindoline phenanthrooxazine, and indolinospiro. Examples of the substituents such as halogen, methyl, ethyl, methylene, ethylene, and hydroxyl groups of the indole ring and benzene ring of phenanthrooxazine can be given.

  Examples of indolinospiroquinolinoxazine compounds include 1,3,3-trimethyl-spiroindoline quinolinoxazine, indole ring of indolinospiroquinolinoxazine and benzene ring halogen such as methyl, ethyl, methylene, ethylene, hydroxyl group, etc. Each substituent can be illustrated.

Among the photochromic compounds, spiropyran derivatives are shown below, but the present invention is not limited thereto.
1,3,3-trimethylindolinobenzopyrospirane, 1,3,3-trimethylindolino-6'-bromobenzopyrrirospirane, 1,3,3-trimethylindolino-8'-methoxybenzopyrriros Examples include pyran, 1,3,3-trimethylindolino-β-naphthopyrilospirane, 1,3,3-trimethylindolino-6′-nitrobenzopyrospirane and the like.

  The pigments may be used alone or in combination of two or more. In addition, pigments and dyes having different specific gravities may be used in combination as long as they do not affect the stability. Furthermore, dyes that do not completely dissolve in water can be used because they can provide a sedimentation-inhibiting effect as insoluble particles. The addition amount of these pigments and / or dyes is not particularly limited as long as a sufficient concentration can be obtained as a water-based ink composition for writing instruments. Further, the particle diameters of these pigments and / or dyes are not particularly limited as long as they are within a range suitable for the recording method used.

  The water-based ink composition for writing according to the present invention comprises a pigment, water, and at least biomass nanofibers.

  As a medium of the water-based ink composition for writing according to the present invention, water and, if necessary, a water-soluble organic solvent are used. Examples of the water-soluble organic solvent include glycols such as glycerin, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,3-butylene glycol, ethylene glycol monomethyl ether, and their lower alkyl ethers, 2-pyrrolidone, N- Examples include vinyl pyrrolidone and urea.

  The water-based ink composition for a writing instrument according to the present invention may contain additives such as a pH adjuster, a preservative, or an antifungal agent as necessary.

  Examples of the pH adjuster include inorganic basic salts such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide and sodium acetate, and organic basic compounds such as water-soluble amine compounds such as triethanolamine and diethanolamine.

  Examples of the preservative or antifungal agent include carboxylic acid, sodium salt of 1,2-benzisothiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2, 3, 5, 6 -Tetrachloro-4- (methylsulfonyl) pyridine and the like.

  In addition, an antifoaming agent such as a fluorine-based surfactant that improves the permeability of the solvent, a nonion, an anion, a cationic surfactant, or dimethylpolysiloxane may be added.

  It should be noted that a non-thermochromic dye or pigment is blended in the ink composition so that a thermochromic image exhibiting tautomerism from colored (1) to colored (2) can be formed by temperature change. Can do.

  The water-based ink composition for writing instruments preferably has an ink viscosity of 1 to 20 mPa · s, more preferably 3 to 15 mPa · s, measured at 30 ° C. using a BL type viscometer at 20 ° C. The water-based ink composition for a writing instrument of the present invention exhibits the maximum effect in suppressing sedimentation of microcapsule pigments when used in a low viscosity ink.

  The blending ratio of the microcapsule pigment can be appropriately selected depending on the type of pigment used and the function to be obtained, but is preferably 1 to 50% by weight based on the total amount of the water-based ink composition for writing instruments. If it is less than this range, the color density tends to decrease, and if it is more than this range, the ink viscosity tends to increase in the ink composition, and it is possible that a low-viscosity ink cannot be obtained.

  The water-based ink composition for writing instruments according to the present invention can be used as a water-based ink for various writing instruments such as fountain pens, ballpoint pens, brush pens, calligraphic pens, and various markers. In particular, it has an ink supply mechanism that utilizes capillary action, such as a writing instrument that has an ink supply mechanism that uses a comb groove such as a fountain pen, and a writing instrument that has an ink supply mechanism that uses a fiber converging body typified by markers. Because writing instruments cannot use inks with high ink viscosity due to their ink supply mechanism, etc., it is necessary to use low-viscosity inks. In conventional writing instrument ink compositions, when writing due to pigment settling, etc. However, in the ink composition for writing instruments according to the present invention, it is possible to suppress the sedimentation of the pigment even in the low viscosity ink, so that it is preferably used. .

  As described above, the water-based ink composition for writing according to the present invention can be provided in various writing tools, and it is possible to form handwriting using the writing tool. Further, when a thermochromic composition represented by a reversible thermochromic microcapsule pigment is used as a colorant, the handwriting (hereinafter sometimes referred to as thermochromic handwriting) The color can be changed by applying a heating tool or a cooling tool.

  Examples of the heating tool include a heating color changing tool equipped with a resistance heating element, a heating color changing tool filled with warm water, and a hair dryer. Preferably, a friction member is used as a means capable of changing color by a simple method. It is done. In particular, an elastic body that does not substantially wear during rubbing is preferable.

  As the friction member, an elastic body such as an elastomer or a plastic foam which is rich in elasticity and can generate frictional heat by rubbing at the time of rubbing is suitable. As the material of the friction member, silicone resin, SEBS resin (styrene ethylene butylene styrene block copolymer), polyester resin, polyester elastomer and the like are used. Although the said friction member can also combine a writing instrument and the friction body which is a member of the arbitrary shapes of a different body, it can also obtain a writing instrument set, However, By providing a friction member in a writing instrument, it will become the thing excellent in portability.

  Examples of the cooling / heating tool include a cooling / heating discoloration tool using a Peltier element, a cooling / heating discoloration tool filled with a refrigerant such as cold water and ice pieces, a cold insulation agent, and application of a refrigerator and a freezer.

    The thermochromic handwriting can be discolored by applying a heat discoloring tool or a cooling / discoloring tool. Examples of the heating color changing tool include an energization heating color changing tool equipped with a resistance heating element such as a PTC element, a heating color changing tool filled with a medium such as hot water, a heating color changing tool using steam or laser light, and an application of a hair dryer. However, preferably, an energization heating discoloration tool is used. Examples of the energization heating color changing tool include an energization heating color changing tool using a thermal head, a heat roller, and a hot stamp.

(Production of microcapsule pigment A)
(I) Component, 2.5 parts of 1,3-dimethyl-6-diethylaminofluorane, (b) Component, 2,2-bis (4'-hydroxyphenyl) hexafluoropropane, 5.0 parts, 1,1- A reversible thermochromic composition having color memory composed of 3.0 parts of bis (4'-hydroxyphenyl) n-decane and 50.0 parts of 4-benzyloxyphenylethyl caprate as component (c) is dissolved by heating. Then, a solution prepared by mixing 30.0 parts of an aromatic isocyanate prepolymer and 40.0 parts of a co-solvent as a wall film material is emulsified and dispersed in an 8% polyvinyl alcohol aqueous solution. 2.5 parts of a functional aliphatic modified amine was added, and stirring was continued to obtain a reversible thermochromic microcapsule pigment suspension. The suspension was centrifuged to isolate a reversible thermochromic microcapsule pigment.
The average particle diameter D of the microcapsule pigment is 2.0 μm, t ₁ : −18 ° C., t ₂ : −9 ° C., t ₃ : 45 ° C., t ₄ : 64 ° C., temperature-sensitive color change color memory. Composition: wall membrane = 2.6: 1.0 A behavior having hysteresis characteristics was exhibited, and the color changed reversibly from orange to colorless and from colorless to orange.

Example 1
Reversible thermochromic microcapsule pigment A 15.0 parts by mass Biomass nanofibers 0.2 parts by mass (cellulose nanofibers aspect ratio 150
Made by Sugino Machine, trade name: BiNFi-s FMa-1202)
Glycerin 20.0 parts by mass Urea 23.0 parts by mass Triethanolamine 0.02 parts by mass Antiseptic and mildew-proofing agent 0.2 parts by mass (1,2-benzisothiazolin-3-one manufactured by Arch Chemical Co., Ltd., trade name: Proxel XL-2)
41.78 parts by weight of water The above composition was stirred and mixed with a homogenizer to obtain a water-based ink composition for writing instruments.
The viscosity of the ink composition was 12.6 mPa · s when measured at 30 rpm at 20 ° C. using a BL type viscometer.

(Example 2)
Reversible thermochromic microcapsule pigment A 15.0 parts by mass Biomass nanofibers 0.15 parts by mass (chitin nanofibers aspect ratio 250
Made by Sugino Machine Co., Ltd., trade name: BiNFi-s SFo-20002)
Glycerin 20.0 parts by mass Urea 23.0 parts by mass Triethanolamine 0.02 parts by mass Antiseptic and mildew-proofing agent 0.2 parts by mass (1,2-benzisothiazolin-3-one manufactured by Arch Chemical Co., Ltd., trade name: Proxel XL-2)
41.63 parts by weight of water The above composition was stirred and mixed with a homogenizer to obtain a water-based ink composition for writing instruments.
The viscosity of the ink composition was 10 mPa · s when measured at 30 rpm at 20 ° C. using a BL type viscometer.

(Example 3)
Reversible thermochromic microcapsule pigment A 15.0 parts by mass Biomass nanofiber 0.1 part by mass (chitosan nanofiber aspect ratio 250
(Sugino Machine, trade name: BiNFi-s EFo-08002)
Glycerin 20.0 parts by mass Urea 23.0 parts by mass Triethanolamine 0.02 parts by mass Antiseptic and mildew-proofing agent 0.2 parts by mass (1,2-benzisothiazolin-3-one manufactured by Arch Chemical Co., Ltd., trade name: Proxel XL-2)
Water 41.68 parts by mass The above composition was stirred and mixed with a homogenizer to obtain a water-based ink composition for a writing instrument.
The viscosity of the ink composition was 10 mPa · s when measured at 30 rpm at 20 ° C. using a BL type viscometer.

(Comparative Example 1)
A water-based ink composition for a writing instrument of Comparative Example 1 was obtained in the same manner as in Example 1 except that the biomass nanofiber was not used.

  The water-based ink compositions for writing instruments obtained in Examples 1 to 3 and Comparative Example 1 were visually evaluated for ink storage stability in the following manner. The results are shown in (Table 1).

分散安定性：実施例１〜３、比較例１の筆記具用水性インキ組成物を２０ｍｌスクリュー管に充填し、分散安定性を目視により確認した。
○：２週間経過後も顔料の沈降はみられず均一に分散した状態を保っているている。
△：２週間経過後にわずかに顔料の沈降がみられるがほとんど均一に分散している。
×：３日後には、顔料の沈降がみられ、顔料の分散安定性を保つことが出来ない。
××：スクリュー管に充填後から顔料の沈降がみられ、分散安定性を保つことが出来ない。

筆記性能試験：（株）パイロットコーポレーション製万年筆（ルシーナ）に、筆記具用水性インキ組成物を充填し、１日間筆記先端を下向きにして放置した後、印刷用紙Ａ（日本製紙（株）社製、しらおい四六判換算５５ｋｇ）に筆記をし、筆記性能を評価した。
○：筆跡にかすれなど無く筆記性良好。
△：筆跡がかすれる。
×：筆記不能。

Dispersion stability: The aqueous ink compositions for writing instruments of Examples 1 to 3 and Comparative Example 1 were filled in a 20 ml screw tube, and the dispersion stability was confirmed by visual observation.
◯: The pigment is not precipitated even after 2 weeks, and is kept in a uniformly dispersed state.
Δ: Slight pigment settling after 2 weeks, but almost uniformly dispersed.
X: After 3 days, precipitation of the pigment was observed, and the dispersion stability of the pigment could not be maintained.
XX: Sedimentation of the pigment is observed after filling the screw tube, and the dispersion stability cannot be maintained.

Written performance test: A fountain pen made by Pilot Corporation (Lucina) was filled with a water-based ink composition for writing instruments and left for one day with the writing tip facing downward, and then printing paper A (manufactured by Nippon Paper Industries Co., Ltd., Written in Shiraoi (sixty-six size equivalent 55kg) and evaluated the writing performance.
○: Writability is good with no blur on the handwriting.
Δ: The handwriting is faded.
X: Writing is impossible.

  As is clear from the results shown in (Table 1), the water-based ink composition for writing instruments according to the present invention maintains good dispersion stability, and good handwriting is obtained even when used by filling the writing instrument. It was revealed that the water-based ink composition for writing instruments has excellent performance. On the other hand, in Comparative Example 1, sedimentation of the microcapsule pigment was observed when stored in the screw tube, and the dispersion stability was inferior to that of the Example. Furthermore, in writing performance, problems occurred and the writing performance was inferior.

  The water-based ink composition for writing instruments according to the present invention can be used as water-based inks for various writing instruments such as fountain pens, ballpoint pens, brush pens, calligraphic pens, and various markers. In particular, it can be suitably used for a writing instrument using a low-viscosity ink.

t ₁ Full color development temperature of microcapsule pigment encapsulating reversible thermochromic composition of heat decoloring type t ₂ Color development start temperature of microcapsule pigment encapsulating reversible thermochromic composition of heat decoloring type t ₃ Heat decoloration Decoloration start temperature of microcapsule pigment encapsulating reversible thermochromic composition of color type t ₄ Complete decolorization temperature of microcapsule pigment encapsulating reversible thermochromic composition of heat decoloring type T ₁ complete decoloring temperature T ₂ heat-coloring type of decoloring starting temperature T ₃ heating color development type reversible thermal discoloration microcapsule pigment enclosing a reversible thermochromic composition of the microcapsule pigment enclosing a reversible thermochromic composition Color development start temperature of the microcapsule pigment encapsulating the composition T ₄ Complete color development temperature of the microcapsule pigment encapsulating the reversible thermochromic composition of the ₄ heating color development type ΔH Hysteresis width

Claims (6)

  A water-based ink composition for a writing instrument, comprising a pigment, water, and biomass nanofibers, and having a viscosity of 1 to 20 mPa · s measured at 30 rpm using a BL type viscometer at 20 ° C.   The water-based ink composition for a writing instrument according to claim 1, wherein the pigment is a microcapsule pigment containing a functional material. The functional material is
(A) a component comprising an electron-donating color-forming organic compound;
(B) a component comprising an electron-accepting compound;
(C) a reaction medium for reversibly causing an electron transfer reaction by the component (a) and the component (b) in a specific temperature range;
The water-based ink composition for a writing instrument according to claim 2, wherein the composition is a reversible thermochromic composition.   The said biomass nanofiber is 1 or 2 or more chosen from a cellulose nanofiber, a chitin nanofiber, and a chitosan nanofiber, The aqueous ink composition for writing instruments of any one of Claims 1-3 characterized by the above-mentioned. .   A writing instrument comprising the water-based ink composition for a writing instrument according to any one of claims 1 to 4.   The writing instrument according to claim 5, wherein the writing instrument is a writing instrument including an ink flow rate adjusting mechanism using a comb groove.

Images