JP2014189610A - Erasable ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an erasable ink composition which can achieve both erasability with an eraser and prevention of dirt caused when handwriting is rubbed with a finger and the like, and which prevents disappearance of handwriting even when placed in a high temperature environment.SOLUTION: Provided is an erasable ink composition comprising at least a pigment, a film-forming resin, a paraffin wax with a melting point of 40 to 60°C, and water.

Description

  The present invention relates to an erasable ink for a writing instrument in which handwriting written on a paper surface can be easily erased with an eraser and is hardly peeled off by normal rubbing caused by touching the handwriting with a finger or the like.

Conventionally, various proposals have been made on inks that can be erased by using an eraser or a special erasing tool. For example, Patent Document 1 discloses a water-based ink composition for an eraser-erasable ballpoint pen using a resin having a glass transition temperature or a minimum film-forming temperature of more than 0 ° C. and less than 40 ° C. This is because when a resin having a glass transition temperature or a minimum film-forming temperature of 40 ° C. or higher is used, the film is not formed at room temperature. For this reason, the film adheres firmly to the paper surface, making it difficult to erase. Therefore, the balance of scratch resistance and erasability with a finger or the like is achieved.
Further, in Patent Document 2, a dissolution medium that melts by heat such as rubbing to dissolve a leuco dye or a developer is used as a decolorizer, and this decolorizer is encapsulated in a capsule together with a leuco dye and a developer. An erasable ink for use as a capsule pigment is disclosed. In this decolorizable ink, when friction is applied to the handwriting and heat is applied to the microcapsule pigment, the decolorizer melts and dissolves the leuco dye or developer, and the dissolution medium becomes the developer. By acting, the color developing effect of the developer on the leuco dye is lost, and the handwriting is in a decolored state.

JP 2000-136339 A JP 2008-280440 A

The water-based ink composition for eraser erasable ballpoint pens using a resin having a glass transition temperature or a minimum film forming temperature of more than 0 ° C. and less than 40 ° C. described in Patent Document 1 has an erasing property at room temperature with reduced fixability. It just balances the resistance and scratch resistance with fingers. Then, a part of the pigment written on the paper surface enters between the paper fibers, and the eraser does not reach and remains in that part, so that sufficient erasability cannot be obtained.
The erasable ink composition described in Patent Document 2 controls the color development and color erasure state by the thermal hysteresis width of the color erasing agent that is a dissolution medium of the leuco dye and the developer. Therefore, when the place where the handwriting or the ink is placed becomes higher than the temperature at which the erasing state is reached, there is a problem that the handwriting is discolored and becomes unreadable or the ink is colorless.

  The gist of the present invention is an erasable ink composition comprising at least a pigment as a colorant, a film-forming resin, a paraffin wax having a melting point of 40 to 60 ° C., and water.

The film formed from the erasable ink composition of the present invention contains at least a color pigment, a film-forming resin, and a paraffin wax having a melting point of 40 to 60 ° C. Since paraffin wax has a linear molecule, its film is hard but brittle. Moreover, when the heat | fever more than melting | fusing point is applied and it melt | dissolves, there exists a property that the viscosity of the liquid will become low compared with other waxes. If a strong rubbing force is applied to the film with an eraser or the like, the film is brittle and cracks or cracks first. Next, since it is heated to about 60 ° C. by rubbing with an eraser or the like, the paraffin wax having a melting point of 40 to 60 ° C. on the surface of the coating melts to become a low viscosity liquid of several mPa · s. This enters the adhesive part between the film and paper fibers from around the cracked part and the film, and acts as a release agent. Then, since the entire film formed of the film-forming resin is peeled off by rubbing with an eraser or the like, it is presumed that the pigment that has entered the gap between the paper fibers is pulled out and high erasability is obtained. However, when lightly rubbing with a finger or the like, the film does not exceed 40 ° C., and the paraffin wax does not melt and the pigment is stretched, and the paper surface is not soiled.
Furthermore, even if this film is placed in an environment higher than the melting point of the wax and the wax melts, the colored pigment remains in place as long as no force such as rubbing is applied, so it is not erased.

Color pigments include carbon black, titanium oxide and other inorganic pigments, azo pigments, naphthol pigments, phthalocyanine pigments, selenium pigments, quinacridone pigments, anthraquinone pigments, dioxane pigments, dioxazine pigments, indigo pigments , Organic pigments such as thioindigo pigments, perinone pigments, indolenone pigments, perylene pigments, azomethine pigments, metal pigments such as aluminum powder and bronze powder, pigment particles dispersed in resin particles, and particle surfaces Are coated with pigments, and dyes are chemically bonded and colored. Specific examples of the colored particles include Love Color 020 (3M) Black (average particle size 3.0 μm), 040 (3M) Red (average particle size 3.0 μm), and 060 (3M) Blue (average particle size). (Diameter: 3.0 μm), 818 (3M) White (average particle size: 3.0 μm), 220 (M) Black (average particle size: 8.5 μm) (above, Dainichi Seika Kogyo Co., Ltd.), Epocolor MA0502B ( And an average particle diameter of 2 ± 1 μm, black), MA0504B (average particle diameter of 4 ± 1 μm, black) (manufactured by Nippon Shokubai Co., Ltd.).
Further, colorless resin particles, inorganic particles, and the like can be used by coloring them with dyes or pigments. As colorless resin particles, Chemisnow MX-150 (average particle size 1.5 μm), MX-180 (average particle size 1.8 μm), MX-300 (average particle size 3.0 μm) made of acrylic resin or styrene resin. MX-500 (average particle size 5.0 μm), MX-1000 (average particle size 10 μm), MX-1500H (average particle size 15 μm), MR-7G (average particle size 7 μm), MR -3GSN (average particle size 3 μm), MR-5GSN (average particle size 5 μm), MR-2G (average particle size 1.0 μm), MR-2HG (average particle size 2.0 μm), MG-10G (Average particle size 9 μm), MP-1400 (average particle size 1.5 μm) (above, manufactured by Soken Chemical Co., Ltd.), SX8705 (P) -01 (average particle size 1.5 μm), SX8703 (A) − 01 (average particle size 2.0 μm) (above JSR Co., Ltd.), Ropeke HP-91 (average particle size 1.0 μm) (above, Rohm and Haas Japan Co., Ltd.), inorganic particles include calcium carbonate, barium sulfate, silica, alumina, Examples include magnesium hydroxide, kaolinite, and clay. The addition amount is preferably 5 to 30% by weight based on the total amount of ink.

  The film-forming resin is used to fix the pigment on the paper and to remove the pigment together with the resin film when the paraffin wax is melted by heat generated by rubbing with an eraser or the like. Specific examples include water-soluble acrylic resins, acrylic resin emulsions, vinyl acetate resin emulsions, urethane resin emulsions, polyvinyl pyrrolidone, and polyvinyl alcohol. As commercially available, Joncryl 52J (nonvolatile content 60.0%), 57J (nonvolatile content 37.0%), 60J (nonvolatile content 34.0%), 63J (nonvolatile content) made of water-soluble acrylic resin. 30.0%), 70J (nonvolatile content 30.0%), PDX-6180 (nonvolatile content 27.0%), HPD-196 (nonvolatile content 36.0%), HPD-96J (nonvolatile content) 34.0%), PDX-6137A (nonvolatile content 28.0%), 6610 (nonvolatile content 33.5%), JDX-6500 (nonvolatile content 29.5%), PDX-6102B (nonvolatile content) 24.5%), PDX-6124 (non-volatile content 24.5%) (above, BASF (Germany), made of acrylic resin emulsion, Joncry 7100 (non-volatile content 48.0%), 711 ( Volatile content 42.0%), PDX-7370 (nonvolatile content 42.0%), PDX-7323 (nonvolatile content 42.0%), PDX-7611 (nonvolatile content 36.5%), 352D ( Nonvolatile content 45.0%), 538J (nonvolatile content 45.0%), PDX-7700 (nonvolatile content 48.0%), PDX-7177 (nonvolatile content 36.0%) (above, manufactured by BASF ( Germany), Polysol S-5J made of vinyl acetate resin emulsion (non-volatile content 52%), AX-590 (non-volatile content 49%), AX-751 (non-volatile content 46%), AX-428J (non-volatile) 46%), AX-510ZL (non-volatile content 43%), AX-951 (non-volatile content 41%), AX-1000 (non-volatile content 39%), BX-8004 (non-volatile content 48%), AX-747L ( Volatile content 50%), P-503 (non-volatile content 40%), PS-120 (non-volatile content 50%), S-65 (non-volatile content 50%) (above, Showa Denko KK), urethane U-coat UX-300 (evaporation residue 38%), UX-310 (evaporation residue 40%), UWS (evaporation residue 35%) consisting of resin emulsion (Sanyo Chemicals Co., Ltd.), polyvinylpyrrolidone PVP K 15 (average molecular weight 10,000), PVP K 30 (average molecular weight 40000), PVP K 60 (average molecular weight 220,000), PVP K 90 (average molecular weight 630000) (manufactured by Tokyo Chemical Industry Co., Ltd.), polyvinyl PVA102, PVA103, PVA105, PVA110, PVA117, PVA120, PVA124, PVAHC, P made of alcohol A-CST, PVA-617, PVA-613, PVA-706, PVA203, PNA205, PVA210, PVA217, PVA220, PVA224, PVA235, PVA217E, PVA217EE, PVA220E, PVA224E, PVA403, PVA405, PVA420, PVA420H, PVA420H, PVA420H 8, L-9, L-9-78, L-10, PVA-505 (manufactured by Kuraray Co., Ltd.) and the like.

  The paraffin wax having a melting point of 40 to 60 ° C. imparts fixability to the paper surface and is mainly composed of a linear saturated hydrocarbon having 20 to 36 carbon atoms. Specifically, heneicosane (melting point: 40.4 ° C.), docosane (melting point: 44.4 ° C.), tricosane (melting point: 47.7 ° C.), tetracosane (melting point: 51.1 ° C.), pentacosane (melting point: 54.0 ° C.), Hexacosane (melting point 56.5 ° C), heptacosane (melting point 60.0 ° C), and a mixture mainly composed of linear saturated hydrocarbons, Paraffin Wax-135 (melting point 59 ° C), 130 (melting point 53 ° C), 125 (melting point 50 ° C.), 155 (melting point 48 ° C.) (manufactured by Nippon Seiwa Co., Ltd.), as an emulsion of paraffin wax, TRASOL PF60 (melting point 60 ° C.), (above, Chukyo Yushi Co., Ltd.) Manufactured). The total amount of film-forming resin and paraffin wax having a melting point of 40 to 60 ° C. is preferably 1 to 30% by weight based on the total amount of ink. Further, the preferred ratio of the water-soluble resin or resin emulsion (solid content) to the paraffin wax having a melting point of 40-60 ° C. is the film-forming resin (solid content): the paraffin wax having the melting point of 40-60 ° C. = 1: 9- 9: 1.

  The solvent is water. The addition amount is preferably 30 to 70% with respect to the total amount of ink. In addition, water-soluble organic solvents such as ethylene glycol, diethylene glycol, glycerin, propylene glycol, and 1,3-butylene glycol can be used in combination with water.

  In addition, since it is formed as an erasable ink composition, a shear thinning agent, a dye compound, a resin dispersion emulsifier and a fixing agent for preventing sedimentation of the colorant, preventing ink leakage from the pen tip, an appropriate discharge amount, etc. Lubricants, antiseptic / antifungal agents, rust preventives, antifoaming agents, dyes, pigments and the like for preventing wear of the ball seats can be appropriately contained. When a coloring component such as a dye or a pigment is added, the decoloring ink component is decolored from the mixed state at the time of color development and the handwriting is in a discolored state.

  A water-soluble polymer compound can be used as the shear thinning agent. For example, gum arabic, gum tragacanth, guar gum, locust bean gum, alginic acid, carrageenan, gelatin, casein, xanthene gum, dextran, welan gum, rhamzan gum, alka gum, methylcellulose, ethylcellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium starch glycolate, sodium alginate, Propylene glycol alginate, hydroxypropylated guar gum, methylcellulose, ethylcellulose, polyvinylpyrrolidone, polyvinylmethylether, polyacrylic acid, carboxyvinyl polymer, polyethylene oxide, copolymer of vinyl acetate and polyvinylpyrrolidone, acrylic resin salt, acrylic acid and alkyl Methacrylate copolymer or Their salts can be used in combination of one or more kinds. The addition amount is preferably 0.05 to 10% with respect to the total amount of ink.

  Examples of the colorant dispersant include anionic surfactants such as higher alcohol sulfates, liquid fatty acid sulfates, alkylallyl sulfonic acids, polyvinyl alcohol, polyoxyethylene alkyl ethers, sorbitan alkyl esters, polyoxy Nonionic surfactants such as ethylene sorbitan alkyl esters, cationic surfactants and amphoteric surfactants. The addition amount is preferably 0.5 to 10% with respect to the total amount of ink.

  In addition to paraffin wax having a melting point of 40 to 60 ° C., other waxes and resins may be used in combination. Examples of waxes that can be used in combination include candelilla wax, carnauba wax, rice wax, wax, jojoba oil, beeswax, lanolin, spermaceti, montan wax, polyethylene wax, Fischer-Tropsch wax, and fatty acid amide wax. The addition amount is preferably 10% or less with respect to the paraffin wax having a melting point of 40 to 60 ° C.

  Examples of antiseptic / antifungal agents include chloroacetamide, 1,2-benzisothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, 2-pyridinethiol-1-oxide sodium salt, sodium dehydroacetate, sodium benzoate, sodium sorbate, potassium sorbate, thiabendazole, phenoxyethanol, sodium fluoride, 4- (2-nitrobutyl) morpholine, 1,3-dimorpholino 2-ethyl-2-nitropropane, 2-bromo-2-nitropropane-1,3-diol, and the like. The addition amount is preferably 0.05 to 5% with respect to the total amount of ink.

  Examples of the surface tension adjustment and antifoaming agent include silicon surfactants and fluorine surfactants. The addition amount is preferably 0.05 to 5% with respect to the total amount of ink.

  It can be dispersed with a roll mill, ball mill, sand grinder, attritor, homogenizer and the like.

  EXAMPLES Next, although an Example and a comparative example demonstrate this invention still in detail, this invention is not limited to the following Example etc.

Example 1
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 15.1 parts by weight Joncryl 711 (styrene acrylic resin emulsion, film-forming resin, nonvolatile content 42 %, Manufactured by BASF (Germany) 10.7 parts by weight TRUSOL PF60 (paraffin wax emulsion, solid content 40% by weight, melting point 60 ° C., manufactured by Chukyo Yushi Co., Ltd.) 1.3 parts by weight water 54.9 parts by weight ethylene Glycol 5.0 parts by weight Glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 8.0 parts by weight The above components were stirred with a magnetic stirrer for 2 hours to obtain an erasable ink. .

Example 2
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 15.1 parts by weight Joncryl 711 (styrene acrylic resin emulsion, film-forming resin, nonvolatile content 42 %, Manufactured by BASF (Germany)) 6.0 parts by weight Torasol PF60 (paraffin wax emulsion, solid content 40% by weight, melting point 60 ° C., manufactured by Chukyo Yushi Co., Ltd.) 6.3 parts by weight water 53.6 parts by weight ethylene Glycol 5.0 parts by weight Glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 9.0 parts by weight The above components were stirred with a magnetic stirrer for 2 hours to obtain an erasable ink. .

Example 3
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 15.1 parts by weight Joncryl 711 (styrene acrylic resin emulsion, film-forming resin, nonvolatile content 42 %, Manufactured by BASF (Germany)) 11.3 parts by weight Torasol PF60 (paraffin wax emulsion, solid content 40% by weight, melting point 60 ° C., manufactured by Chukyo Yushi Co., Ltd.) 1.2 parts by weight water 52.4 parts by weight ethylene Glycol 5.0 parts by weight Glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 10.0 parts by weight The above components were stirred with a magnetic stirrer for 2 hours to obtain an erasable ink. .

Example 4
(Adjustment of Haneiko sun wax emulsion)
To 60 parts by weight of 5% PVA205 (emulsifier polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) aqueous solution heated to 50 ° C., 40 parts by weight of melted heneicosane is added and emulsified with a homogenizer at 6500 RPM for 10 minutes. Got.
(Adjustment of erasable ink composition)
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 10.6 parts by weight Joncryl 711 (styrene acrylic resin emulsion, film-forming resin, nonvolatile content 42 %, Manufactured by BASF, Germany) 6.0 parts by weight Heneicosan wax emulsion (solid content 40% by weight, melting point 40.4 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) 6.3 parts by weight water 57.1 parts by weight Ethylene glycol 5.0 parts by weight Glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 10.0 parts by weight The above components were stirred with a magnetic stirrer for 2 hours to obtain an erasable ink. It was.

Example 5
Laborol 020 (3M) Black (black resin particles, average particle size 3.0 μm, manufactured by Dainichi Seika Co., Ltd.) 10.0 parts by weight TRUSOL PF60 (paraffin wax emulsion, solid content 40% by weight, melting point 60 ° C., Chukyo) (Oil & Fats Co., Ltd.) 5.0 parts by weight Joncryl 63J (styrene-acrylic resin aqueous solution, film-forming resin, solid content 30%, manufactured by BASF, Germany) 14.0 parts by weight water 51.0 parts by weight ethylene glycol 0 parts by weight glycerin 5.0 parts by weight Kelzan AR6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 10.0 parts by weight Each of the above components except for TRUSOL PF60 and Kelzan AR6% aqueous solution was dispersed for 24 hours in a ball mill. Torasol PF60 and Kelzan AR 6% aqueous solution were added and stirred with a magnetic stirrer for 2 hours to obtain an erasable ink.

Comparative Example 1
(Eicosan wax emulsion adjustment)
40 parts by weight of melted eicosane (melting point: 37.0 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) is added to 60 parts by weight of an aqueous solution of 5% PVA205 (emulsifier, polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) heated to 50 ° C. The mixture was emulsified with a homogenizer at 6500 RPM for 10 minutes to obtain an eicosan wax emulsion.
(Adjustment of erasable ink composition)
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 10.6 parts by weight Joncryl 711 (styrene acrylic resin emulsion, film-forming resin, nonvolatile content 42 %, Manufactured by BASF (Germany)) 6.0 parts by weight Eicosane wax emulsion (solid content 40% by weight, melting point 37.0 ° C., manufactured by Tokyo Chemical Industry Co., Ltd.) 6.3 parts by weight Water 57.1 parts by weight Ethylene glycol 5.0 parts by weight Glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 10.0 parts by weight The above components were stirred with a magnetic stirrer for 2 hours to obtain an erasable ink. It was.

Comparative Example 2
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 10.6 parts by weight Joncryl 711 (styrene acrylic resin emulsion, film-forming resin, nonvolatile content 42 %, Manufactured by BASF (Germany)) 6.0 parts by weight Cybinol PC-10 (paraffin wax emulsion, solid content 50%, melting point 64 ° C.
5.0 parts by weight water 58.4 parts by weight ethylene glycol 5.0 parts by weight glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 10.0 parts by weight Part Each of the above components was stirred with a magnetic stirrer for 2 hours to obtain an erasable ink.

Comparative Example 3
(Preparation of polyoxyethylene behenyl ether emulsion)
40 weight parts of melted NIKKOL BB-10 (polyoxyethylene behenyl ether, manufactured by Nikko Chemicals Co., Ltd.) in 60 parts by weight of an aqueous solution of 5% PVA205 (emulsifier, polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) heated to 80 ° C. In addition, the mixture was emulsified with a homogenizer at 6500 RPM for 10 minutes to obtain a polyoxyethylene behenyl ether emulsion.
(Adjustment of erasable ink composition)
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 10.6 parts by weight Joncryl 711 (styrene acrylic resin emulsion, film-forming resin, nonvolatile content 42 %, Manufactured by BASF, Germany) 6.0 parts by weight polyoxyethylene behenyl ether emulsion (solid content 40% by weight, melting point 50-60)
° C) 6.3 parts by weight water 57.1 parts by weight ethylene glycol 5.0 parts by weight glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 10.0 parts by weight Stirring with a tic stirrer for 2 hours gave an erasable ink.

Comparative Example 4
Thermochromic microcapsule pigment (interfacial polymerization method)
(Creation of core material emulsion)
2- (2-Chloroanilino) -6-di-n-butylaminofluorane (black leuco dye)
4.5 parts by weight 1,1-bis (4′-hydroxyphenyl) n-decane (developer) 4.5 parts by weight 1,1-bis (4′-hydroxyphenyl) hexafluoropropane (developer)
7.5 parts by weight 4-benzyloxyphenylethyl caprate (decolorant) 50.0 parts by weight The above components were stirred with a magnetic stirrer at 50 ° C. for 1 hour to obtain thermochromic compound 1.
Thermochromic compound 1 56.5 parts by weight Coronate HX (polyisocyanate, manufactured by Nippon Polyurethane Industry Co., Ltd.) 30.0 parts by weight Isobutyl acetate 40.0 parts by weight The above components were stirred with a magnetic stirrer for 1 hour and heated. An isobutyl acetate solution of the color changing compound and polyisocyanate was obtained.
Water 92.0 parts by weight PVA205 (polyvinyl alcohol, manufactured by Kuraray Co., Ltd.) 8.0 parts by weight The above components were mixed and stirred with a magnetic stirrer for 1 hour to obtain an aqueous polyvinyl alcohol solution.
70.0 parts by weight of a thermochromic compound and a polyisocyanate isobutyl acetate solution are added to 66.5 parts by weight of a polyvinyl alcohol aqueous solution, and the mixture is stirred for 20 minutes at 13500 rpm with a homogenizer, and the thermochromic compound and isobutyl acetate of a polyisocyanate are mixed. An aqueous dispersion having the solution as droplets was obtained.
(Adjustment of curing agent)
A mixture of 3.0 parts by weight of diethyltriamine (curing agent for capsule film) and 27.0 parts by weight of water was stirred with a magnetic stirrer to obtain a diethyltriamine aqueous solution.
(Microencapsulation)
Add 136.5 parts by weight of the above core substance emulsion and 30.0 parts by weight of diethyltriamine aqueous solution, and stir for 3 hours with a magnetic stirrer on the surface of the core substance droplet of the isobutyl acetate solution of the discolorable compound and polyisocyanate. A microcapsule dispersion having an average particle size of 3.0 μm was obtained by polymerizing polyurethane by reaction of polyisocyanate and diethyltriamine.
(Ink)
Microcapsule dispersion 25.70 parts by weight Succinoglucan (shear thinning agent, manufactured by Sanki Co., Ltd.) 0.20 parts by weight urea 5.50 parts by weight glycerin 7.50 parts by weight Nopco SW-WET-366 ( Non-ionic surfactant, manufactured by San Nopco)
0.03 parts by weight FS Antifoam 013A (silicone defoaming agent, manufactured by Toray Dow Corning Co., Ltd.)
0.15 parts by weight Proxel XL-2 (benzoisothiazolin-3-one, manufactured by ICI Japan Ltd.)
0.10 parts by weight Prisurf A212C (polyoxyalkylene alkyl ether phosphate, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.50 parts by weight Triethanolamine 0.50 parts by weight Water 59.82 parts by weight Succinoglucan Each of the above components is dispersed with a magnetic stirrer, succinoglucan is added, and the mixture is stirred with a magnetic stirrer for 2 hours. Then, it was left to stand at −20 ° C. for 24 hours to obtain a black ink composition.

Comparative Example 5
CMX-600RBK (W) (black colored resin particles, solid content 66% by weight, average particle size 6 μm, manufactured by Soken Chemical Co., Ltd.) 15.1 parts by weight Nipol MH5055 (modified styrene / acrylic resin, non-film-forming resin ( Resin particles), Nippon Zeon Co., Ltd.) 5.0 parts by weight Torasol PF60 (paraffin wax emulsion, solid content 40% by weight, melting point 60 ° C., manufactured by Chukyo Yushi Co., Ltd.) 6.3 parts by weight Water 54.6 parts by weight Ethylene glycol 5.0 parts by weight Glycerin 5.0 parts by weight Kelzan AR 6% aqueous solution (xanthan gum, manufactured by Sanki Co., Ltd.) 9.0 parts by weight The above components are stirred with a magnetic stirrer for 2 hours to obtain an erasable ink. It was.

  The following tests were performed on the ink compositions of these Examples and Comparative Examples. The results are shown in Table 1.

Eraser erasability test The erasable ink compositions obtained in the examples and comparative examples were filled in a writing instrument (hybrid ballpoint pen K105 (ball diameter 0.5 mm) manufactured by Pentel Co., Ltd.) and fine paper (JIS P3201 writing paper A). Next, write a 5cm straight line in a width of 1.5cm with no gap between the straight line, erase 10 times with Pentel Click Eraser For Pro (ZE31-A), and then use the color computer to erase the Y value. Was measured.

Written rubbing test The erasable ink compositions obtained in the examples and comparative examples were filled in a writing instrument (hybrid ballpoint pen K105 (ball diameter 0.5 mm) manufactured by Pentel Co., Ltd.) and used on fine paper (JIS P3201 writing paper A). After writing, the finger was placed on the handwriting for 10 seconds and then rubbed once with the finger to visually check the scratched portion.
○: Slightly soiled ×: Stained

Handwriting heat resistance test Example and erasable ink composition obtained in Comparative Example were filled in a writing instrument (hybrid ballpoint pen K105 (ball diameter 0.5 mm) manufactured by Pentel Co., Ltd.) and high quality paper (JIS P3201 writing paper A) After writing a straight line of 5 cm in parallel within a width of 1.5 cm with no gap between the straight lines, the handwriting was left at 70 ° C. for 1 hour, and the Y value of the erased portion was measured with a color computer.

  The erasability of the erasable ink compositions of Examples 1 to 5 is better than that of Comparative Examples 2 to 3. In the ink of Comparative Example 1, the paper surface was soiled by the degree of rubbing process by the palm, and when the erasable ink composition of Comparative Example 4 was placed in an environment of 70 ° C., the handwriting was decolored. Furthermore, the erasable ink composition of Comparative Example 5 using a non-film-forming resin was not sufficiently erasable because the colored pigment that had entered the gaps in the paper fibers could not be removed even when rubbed with an eraser. It was.

Claims (1)

An erasable ink composition comprising at least a coloring pigment, a film-forming resin, paraffin wax having a melting point of 40 to 60 ° C., and water.