JP2007231141A - Correction liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a correction liquid having rapid dryness of a coated film and good stability (re-dispersibility) with time. <P>SOLUTION: In the correction liquid composed of at least titanium oxide, a liquid medium and an acrylic resin which is soluble in the liquid medium, the liquid medium comprises at least a hydrocarbon solvent having ≥700 vaporization rate index at 20°C and ≥6.8 and ≤7.4 solubility parameter and a hydrocarbon solvent having having ≥700 vaporization rate index at 20°C and ≥8.0 and ≤8.1 solubility parameter, and the hydrocarbon solvent having ≥6.8 and ≤7.4 solubility parameter has vaporization rate index which is smaller than that of the hydrocarbon solvent having ≥8.0 and ≤8.1 solubility parameter. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a correction liquid for concealing and erasing typographical characters, and more particularly to a correction liquid having excellent coating film drying properties.

Conventionally, a correction liquid comprising at least a concealing material such as titanium oxide, a hydrocarbon solvent such as methylcyclohexane, and a resin such as acrylic soluble in the solvent is known (see Patent Document 1).
In addition, the correction liquid may correct typographical errors and rewrite on the coating film, and it is preferable that the time until the rewriting is short. However, with a correction liquid using a hydrocarbon solvent such as methylcyclohexane and a resin soluble in the solvent, the solvent evaporation rate is slow, and it takes time for the solvent to evaporate. Had to wait a long time. Therefore, a method using a solvent having a high evaporation rate such as cyclohexane has also been proposed (see Patent Document 2).
JP 57-24765 A Japanese Patent Laid-Open No. 1-292074

When a solvent having a high evaporation rate is used, a thin film is formed on the surface of the coating film during the drying of the coating film, and the solvent under the coating film is difficult to evaporate.
By the way, the evaporation of the solvent from the resin solution by the resin and the solvent that dissolves the resin shows almost the same drying rate as when the solvent is alone at the beginning of drying, but the evaporation rate becomes slower as the solvent evaporates. Become. This tendency occurs at an earlier stage as the solubility parameters of the solvent and the resin are closer, and the evaporation rate becomes slower as the solvent becomes smaller.
The relationship between the organic solvent and the resin soluble in it is that the solubility parameter is close, but as the organic solvent for dissolving the resin, the correction liquid using a solvent whose solubility parameter is close to the resin is the initial one. The drying speed is the same as that when the resin is not dissolved, but the solvent is retained in the resin as the solvent evaporates, and the drying speed becomes slower. In addition, the combination of the resin and the solvent has a good resin solubility, and the resin molecules are sufficiently spread and adsorbed flatly on the titanium oxide surface. Therefore, the dispersibility is good, but there is nothing to support titanium oxide in the liquid medium, so it settles with time and produces a hard cake.
On the other hand, the correction liquid using a solvent whose solubility parameter is far from the resin has the same initial drying speed as that when the resin is not dissolved. This solvent is difficult to be retained in the resin, and the drying speed decreases with evaporation. Since it is small, a decrease in drying property in the later stage of evaporation is small. In addition, this resin / solvent combination has poor resin solubility, and the resin molecules do not spread sufficiently. Therefore, the dispersibility of titanium oxide is reduced and the titanium oxide is easily settled, so that this also forms a hard cake.

  As an improvement measure, the present invention relates to a correction liquid comprising at least a titanium oxide, a liquid medium, and an acrylic resin soluble in the liquid medium, wherein the liquid medium is a hydrocarbon solvent in which the acrylic resin is soluble. At least a hydrocarbon solvent having a solubility parameter of 6.8 or more and 7.4 or less and a hydrocarbon solvent having a solubility parameter of 8.0 or more and 8.1 or less, and having a solubility parameter of The gist is a correction liquid in which a hydrocarbon solvent having a solubility parameter of 6.8 to 7.4 has a lower evaporation rate index than a hydrocarbon solvent having a solubility parameter of 8.0 to 8.1.

The problems to be solved are that it takes a long time to re-write the corrected coating film, and that titanium oxide settles with time, producing a hard cake and cannot be redispersed.
By the way, the solubility parameter of the acrylic resin used in the present invention is approximately 8.0 to 10.0, the evaporation rate index at 20 ° C. is 700 or more, and the solubility parameter is 6.8 to 7.4. A hydrocarbon solvent having at least a hydrogen solvent and a hydrocarbon solvent having a solubility parameter of 8.0 to 8.1 and having a solubility parameter of 6.8 to 7.4 has a solubility parameter of 8.0 to 8. By making the evaporation rate index smaller than that of hydrocarbon solvents of 1 or less, at the beginning of drying, there are more hydrocarbon solvents having a large evaporation rate index of 8.0 or more and 8.1 or less. Evaporate. Therefore, as the evaporation proceeds, the proportion of hydrocarbon solvents having a solubility parameter of 6.8 or more and 7.4 or less increases, so when a hydrocarbon solvent having a solubility parameter of 8.08 or more and 8.1 or less is used alone. Thus, a correction liquid having a small decrease in the evaporation rate in the latter period and a high evaporation rate from the initial stage to the latter stage of drying can be obtained.

Also, by increasing the pigment volume concentration, the ratio of the resin in the coating can be reduced, and more voids can be formed in the coating, so a thin coating can be formed during the drying process using a solvent with a high evaporation rate index. It is possible to suppress as much as possible that the drying rate tends to decrease with evaporation.
Furthermore, by adding the acicular particles, the acicular particles are intricately entangled in the coating film and the concealing material is prevented from being densely overlapped, and a large number of fine voids opened in the coating film are formed. As a result, the drying speed of the coating film is further increased.

  In terms of stability over time, by using a hydrocarbon solvent having a solubility parameter of 6.8 or more and 7.4 or less and a hydrocarbon solvent having a solubility parameter of 8.0 or more and 8.1 or less, the solubility parameter is 8.0. Although the spread of the resin is lower than when the hydrocarbon solvent of 8.1 or less is used alone, the titanium oxide can be sufficiently dispersed. However, since the resin does not spread sufficiently, it does not adsorb flatly on the titanium oxide surface, and there are many portions on the titanium oxide surface where no resin is adsorbed, and the portions where the resin is not adsorbed contact each other To do.

  In a hydrocarbon solvent, since the force of strong polarities between titanium oxides cannot be broken, the contact state is maintained. As a result, since the titanium oxide particles form a weak network due to aggregation, it is presumed that a correction liquid with good redispersion is obtained without generating a hard cake.

Details will be described below.
The correction liquid is used to conceal handwriting and figures that are difficult to erase with an eraser such as a fountain pen or ballpoint pen. The correction liquid covers typographical characters and re-writes on it if necessary. The basic blending is composed of a coloring component that becomes a masking material, a fixing component for the writing surface, and a liquid medium that dissolves and / or disperses them.

  Titanium oxide is a white pigment having the highest hiding power in consideration of the most white color on the paper surface and covering the ground as a correction liquid. Specific examples of the product include TITON SR-1 (specific gravity 4.1), R-650 (specific gravity 4.1), R-62N (specific gravity 3.9), R-42 (specific gravity 4.1). R-7E (specific gravity 3.9), R-21 (specific gravity 4.0) (above, manufactured by Sakai Chemical Industry Co., Ltd.), Kronos KR-310 (specific gravity 4.2), KR-380 ( Specific gravity 4.2), 480 (specific gravity 4.2) (made by Titanium Industry Co., Ltd.), Taipure R-900 (specific gravity 4.0), R-902 (specific gravity 4.0), R- 960 (specific gravity 3.9), R-931 (specific gravity 3.6) (manufactured by DuPont Japan Limited), TITANIX JR-301 (specific gravity 4.1), JR-805 (specific gravity 3.9) JR-603 (specific gravity 4.0), JR800 (specific gravity 3.9), JR-403 (specific gravity 4.0), JR 701 (specific gravity 4.1) (above, manufactured by Teika Co., Ltd.). The amount of titanium oxide added is preferably 30 to 60% by weight based on the total amount of ink.

  In addition, pigments such as carbon black, iron oxide, silica, alumina, calcium carbonate, mica, aluminum silicate, and resin particles that are insoluble in the solvent used to adjust the color tone and gloss of the correction coating Can also be used together. The amount used is preferably 0.01 to 20% by weight based on titanium oxide.

In the present invention, the solvent is a combination of at least two solvents selected from the group A and a solvent selected from the group B, and the evaporation rate index at 20 ° C. of the solvent selected from the group A is: It is necessary to be lower than the evaporation rate index at 20 ° C. of the solvent selected from Group B.
The solvent selected from Group A has a solubility parameter of 6.8 to 7.4. Specific examples thereof include n-hexane (evaporation rate index 1150 at 20 ° C., solubility parameter 7.26), 2-methylpentane. (Evaporation rate index 1626 at 20 ° C., solubility parameter 7.06), 3-methylpentane (evaporation rate index 1455 at 20 ° C., solubility parameter 7.18), 2,2-dibutylbutane (evaporation rate index 2486 at 20 ° C.) , Solubility parameter 6.83), 2,3-dimethylbutane (evaporation rate index 1812 at 20 ° C., solubility parameter 7.04), 2,2-dimethylhexane (evaporation rate index 924 at 20 ° C., solubility parameter 6.92) ), 2,4-dimethylpentane (evaporation rate index 861 at 20 ° C., solubility parameter) 7.02), 3,3-dimethylpentane (evaporation rate index 725 at 20 ° C., solubility parameter 7.22), 2,2,3-trimethylbutane (evaporation rate index 902 at 20 ° C., solubility parameter 7.10) The solvent selected from Group B has a solubility parameter of 8.0 to 8.1, and specific examples thereof include cyclopentane (evaporation rate index 2003 at 20 ° C., solubility parameter 8.08), And methylcyclopentane (evaporation rate index 1021 at 20 ° C., solubility parameter 8.05), cyclohexane (evaporation rate index 718 at 20 ° C., solubility parameter 8.05) and the like. The amount used is preferably 35 to 60% by weight based on the total amount of ink. Further, the ratio of the solvent selected from the A group and the solvent selected from the B group is preferably A group / B group = 1/3 to 3/1.

  The evaporation rate index is a value indicating the easiness of evaporation of the solvent, and is a ratio of the evaporation rate with respect to butyl acetate (evaporation rate 100) and is calculated by the following equation (Equation 1).

  The solubility parameter is a value that characterizes the dissolution of a solvent, a resin, etc., and is calculated from the following formula (Equation 2).

  In addition, methylcyclohexane, normal octane, ethylcyclohexane, or the like may be used in order to adjust the drying speed or prevent the thin coating from spreading on the surface of the coating during drying. These can be used alone or in combination. The amount of these solvents used is preferably 20% by weight or less based on the total amount of ink.

  The acrylic resin soluble in the hydrocarbon solvent causes dispersion of the pigment and fixing of the correction liquid onto the paper surface. Usable monomers are methyl acrylate, ethyl acrylate, isopropyl acrylate, normal butyl acrylate, 2-ethylhexyl acrylate as acrylate ester, and methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl as methacrylic acid ester. Examples include methacrylate, isobutyl methacrylate, 2methyl-2-propyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, lauryl methacrylate, cetyl methacrylate, stearyl methacrylate, oleyl methacrylate, cyclohexyl methacrylate, and benzyl methacrylate. As cationic monomers, N, N-dimethylaminopropyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (Meth) acrylate, N, N-diisopropylaminoethyl (meth) acrylate, N, N-di-2methyl-2propylaminoethyl (meth) acrylate, N, N-dicyclohexylaminoethyl (meth) acrylate, N, N Examples thereof include dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide N, N-dimethylaminopropyl (meth) acrylamide, and N, N-diethylaminopropyl (meth) acrylamide. In addition to these monomers, vinyl acetate, styrene, vinyl toluene, maleic acid, itaconic acid, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, 2-hydroxypropyl acrylate, hydroxypropyl acrylate, acrylamide, N- A copolymerizable vinyl monomer such as methylolacrylamide, diacetoneacrylamide, or glycidylmethacrylate can also be contained.

  Here, the weight average molecular weight is a value measured by a GPC (Gel Permeation Chromatography) analysis method, and is a value obtained by measuring the weight average molecular weight using a polystyrene gel column as a packed column.

  In consideration of the adhesion of the coating film to paper, the glass transition point is preferably -70 ° C to 50 ° C. The glass transition point is the temperature at which the polymer substance changes from glassy to rubbery. The glass transition point is calculated by the following equation (Equation 3) from the glass transition point of the homopolymer of the resin monomer and the weight fraction.

  The pigment volume concentration as used in the field of this invention is calculated | required by a following formula (Formula 4).

  In order to increase the evaporation rate of the solvent of the correction fluid, it is better that the number of resins that can easily hold the solvent is as small as possible. However, when the amount of the resin is decreased, the fixing property of the concealing material to the paper surface is lowered, and further, the sedimentation of the concealing material with time is increased. Therefore, by setting the weight average molecular weight of the resin to 200,000 or more and the pigment volume concentration to 70% or more, a correction liquid having both the coating film drying property, the fixing property to the paper surface, and the pigment settling prevention property can be obtained.

Needle-like particles are intricately entangled with each other in the dry paint film to increase the voids in the paint film, improve the escape of the solvent even if a thin dry film can be formed on the surface of the paint film, and the strength of the paint film It is used to raise
Specifically, silicon nitride whisker, silicon carbide whisker, aluminum borate whisker, zinc oxide whisker, potassium titanate whisker, whisker-like calcium carbonate, whisker-like titanium oxide, alumina diameter whisker, magnesia whisker, mullite whisker, magnesium borate Whisker, titanium boride whisker, alumina and alumina silica short fiber, silica short fiber, zirconia fiber (short fiber), kaolin-based ceramic short fiber, etc., and the amount added depends on the specific gravity and length of the particles, but the ink About 2 to 20% by weight is preferable with respect to the total amount. Moreover, the preferable particle size (major axis) of the acicular particles is 3 to 40 μm.

  For pigment dispersion stability, nonionic surfactants such as alkyl sulfate ester salts, alkyl phosphate salts, polycarboxylic acid polymers, polyethylene alkyl ethers, glycerin fatty acid esters, polyoxyethylene fatty acid esters, etc. A dispersant such as an ionic surfactant, a quaternary ammonium salt, or an alkylamine salt can be added.

  The ink is obtained by dispersing and mixing the above components using a stirring and dispersing machine such as a ball mill, an attritor, a sand grinder, and an impeller.

Hereinafter, the present invention will be described in detail based on examples.
Production Example of Resin (Acrylic Resin) The materials listed in Table 1 below were charged into a 500 ml reaction vessel equipped with a stirrer, nitrogen gas inlet, thermometer, and reflux condenser, and in a nitrogen gas stream at 80 ° C. for 7 hours. Polymerization was conducted with stirring to obtain a transparent and viscous polymer component.

Example 1
TITANIX JR701 (titanium oxide, manufactured by Teika Co., Ltd.) 45.0 parts by weight Dynal BR1122 (acrylic resin, weight average molecular weight 180000, manufactured by Mitsubishi Rayon Co., Ltd.) 7.1 parts by weight 2,4-dimethylpentane (20 ° C. Evaporation rate index 861, solubility parameter 7.02)
13.0 parts by weight methylcyclopentane (20 ° C. evaporation rate index 1021, solubility parameter 8.05)
33.9 parts by weight BYK-108 (surfactant, manufactured by BYK-Chemie (Germany)) 1.0 part by weight Each of the above components was dispersed in a ball mill for 24 hours to obtain a correction liquid having a pigment volume concentration of 65%. .

Example 2
TITANIX JR301 (titanium oxide, manufactured by Teika Co., Ltd.) 35.0 parts by weight Dynal BR102 (acrylic resin, weight average molecular weight 360000, manufactured by Mitsubishi Rayon Co., Ltd.) 4.7 parts by weight 2-methylpentane (20 ° C. evaporation rate) Index 1626, solubility parameter 7.06)
12.5 parts by weight 3-methylpentane (20 ° C. evaporation rate index 1454, solubility parameter 7.18)
12.5 parts by weight cyclopentane (20 ° C. evaporation rate index 2003, solubility parameter 8.08)
25.0 parts by weight Whiscal A (acicular calcium carbonate, manufactured by Maruo Calcium Co., Ltd.) 9.0 parts by weight antigel (surfactant, manufactured by Bernd Schwegmann (Germany))
1.3 parts by weight The above components were dispersed in a ball mill for 24 hours to obtain a correction liquid having a pigment volume concentration of 75%.

Example 3
TITONE R62N (titanium oxide manufactured by Sakai Chemical Industry Co., Ltd.) 50.0 parts by weight Resin 1 (see Table 1) 12.0 parts by weight 2-methylpentane (20 ° C. evaporation rate index 1626, solubility parameter 7.06)
14.0 parts by weight 3-methylpentane (20 ° C. evaporation rate index 1454, solubility parameter 7.18)
14.0 parts by weight cyclopentane (20 ° C. evaporation rate index 2003, solubility parameter 8.08)
9.0 parts by weight DISPARON PW36 (surfactant, manufactured by Enomoto Kasei Co., Ltd.) 1.0 parts by weight Each of the above components was dispersed for 24 hours with a ball mill to obtain a correction liquid having a pigment volume concentration of 80%.

Example 4
TITANIX JR701 (titanium oxide, manufactured by Teika Co., Ltd.) 40.0 parts by weight Resin 2 7.7 parts by weight 2-methylpentane (20 ° C. evaporation rate index 1626, solubility parameter 7.06)
12.0 parts by weight 3-methylpentane (20 ° C. evaporation rate index 1454, solubility parameter 7.18)
11.9 parts by weight cyclopentane (20 ° C evaporation rate index 2003, solubility parameter 8.08)
23.9 parts by weight Anti-Terra-P (surfactant, BYK-Chemie (Germany))
1.0 part by weight Whiscal A (described above) 3.5 parts by weight Each of the above components was dispersed in a ball mill for 24 hours to obtain a correction liquid having a pigment volume concentration of 85%.

Comparative Example 1
A correction fluid was obtained in the same manner as in Example 1 except that 2,4-dimethylpentane was removed from Example 1 and that methylcyclopentane was changed to 46.9 parts by weight.

Comparative Example 2
Except for 2,4-dimethylpentane from Example 1, except that n-hexane (20 ° C evaporation rate index 1150, solubility parameter 7.26) was changed to 13.0 parts by weight, the same modification as in Example 1 was made. A liquid was obtained.

Comparative Example 3
A correction fluid was obtained in the same manner as in Example 1 except that 2,4-dimethylpentane and methylcyclopentane were excluded from Example 1 and that 46.9 parts by weight of n-hexane was used.

Coating Film Drying Test The correction solution obtained in each Example and Comparative Example was applied to high-quality paper with a 250 μ applicator, and the time during which writing on the coating film with a ballpoint pen was taken as the coating film drying time.

Redispersibility test 10 ml of the correction solution obtained in each example and comparative example was collected in a screw mouth bottle (S-5, manufactured by Nidec Rika Glass Co., Ltd.), put one 8 mmφ stainless steel ball, and sealed. Leave at 80 ° C. for 1 month. Then, the screw bottle was shaken and the number of times until the ball moved was measured.

  As described above in detail, the correction liquid of the present invention has good dryness and good redispersibility.

Claims (4)

In a correction liquid comprising at least titanium oxide, a liquid medium, and an acrylic resin soluble in the liquid medium, the liquid medium is a hydrocarbon solvent in which the acrylic resin is soluble, and the evaporation rate index at 20 ° C. is 700 or more. A hydrocarbon solvent having a solubility parameter of 6.8 or more and 7.4 or less and a hydrocarbon solvent having a solubility parameter of 8.0 or more and 8.1 or less, and having a solubility parameter of 6.8 or more and 7.4 or less A correction fluid in which a hydrocarbon solvent has a lower evaporation rate index than a hydrocarbon solvent having a solubility parameter of 8.0 or more and 8.1 or less. The total amount of the hydrocarbon solvent having an evaporation rate index at 20 ° C. of 700 or more and a solubility parameter of 6.8 to 7.4 and a hydrocarbon solvent having a solubility parameter of 8.0 to 8.1 is the total solvent. The correction fluid according to claim 1, wherein the correction fluid is 75% or more. The correction liquid according to claim 1 or 2, wherein the acrylic resin has a weight average molecular weight of 200,000 or more and a pigment volume concentration of 70% or more. The correction liquid according to claim 1 or 2, further comprising acicular particles.