JP2009057403A - Oily ink for ballpoint pen - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oily ink for ballpoint pens, that hardly cause the blurring of handwriting at the beginning of the writing, even when left in a state contacted with outside air for a long time. <P>SOLUTION: This oily ink for ballpoint pens comprises a colorant, an organic solvent, and a copolymer comprising the constituting units of a monomer having at least carboxyl group in the molecule and the constituting units of a monomer having a styrene group, or a hydroxyl group-having polyvinyl butyral resin, and a silicone whose both ends are modified with amino groups. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an oil-based ink for ballpoint pens that can be smoothly written without blurring of handwriting at the time of writing even after long-term storage.

As a pigment dispersant in oil-based ink, Patent Document 1 discloses an ink using a styrene / acrylic acid copolymer and polyvinyl butyral. Patent Document 2 discloses an ink using polyvinyl butyral having an average molecular weight of 15,000 to 60000. Further, Patent Document 3 discloses an ink jet ink using various amino-modified silicone oils as a pigment dispersant.
Japanese Patent Laid-Open No. 10-330677 JP 2001-123102 A JP 2004-217703 A

  As in the invention described in the above-mentioned patent document, it is possible to improve the dispersibility of the pigment as an ink by selecting a dispersant, but a liquid medium such as a solvent is a component that gradually volatilizes, particularly like a pen tip. The solvent volatilizes at the part that comes into contact with the outside air, the ink pigment concentration and the solid content concentration such as resin are increased, the fluidity of the ink is inhibited, the rotation of the ball is inhibited, and the handwriting is blurred There were problems such as.

  That is, the present invention relates to a colorant, an organic solvent, a copolymer containing at least a monomer having a carboxylic acid group in the molecule and a monomer having a styrene group as a constituent unit or a polyvinyl butyral resin having a hydroxyl group, The gist is an oil-based ink for ballpoint pens containing at least a modified silicone.

When a copolymer containing at least a monomer having a carboxylic acid group in the molecule and a monomer having a styrene group or a polyvinyl butyral resin having a hydroxyl group and a both-end amino-modified silicone are used in combination, the functionality of the both-end amino-modified silicone Since the distance between the parts is sufficiently far away, the network structure due to the hydrogen bond between the two becomes moderate and moderate, and in a stationary state where no external force is applied, the liquid medium is held plentifully, apparently swollen Forms a system, does not form an interface where solids such as pigments and resins are present at high concentrations, and forms a gently swelled state, so external forces such as writing pressure are applied. It is presumed that the ink can flow easily and does not hinder the rotation of the ball, so that ink discharge can form a sufficient handwriting.
Therefore, even if the ink is left in contact with the outside air for a long time, it is possible to obtain ink that is less likely to cause handwriting blurring at the beginning of writing.

The invention is described in detail below.
Examples of the colorant include pigments and dyes.
As the pigment, those generally used can be used. For example,
Carbon black, insoluble azo pigment, azo lake pigment, condensed azo pigment, diketopyrrolopyrrole pigment, phthalocyanine pigment, quinacridone pigment, isoindolinone pigment, isoindoline pigment, anthraquinone pigment, dioxazine pigment, Conventionally known general pigments such as organic pigments such as indigo pigments, thioindigo pigments, quinophthalone pigments, perinone and perylene pigments can be used. These pigments may be used alone or in combination of two or more.
The amount of these pigments to be used is preferably 1% by weight or more and 40% by weight or less, and more preferably 3% by weight or more and 20% by weight or less, based on the total amount of oil-based ink for ballpoint pens. If the amount used is less than 1% by weight, the handwriting is too thin and difficult to read. On the other hand, when the amount is more than 40% by weight, it becomes easy to cause a problem that writing becomes unsatisfactory due to clogging due to sedimentation with time, and an increase in the solid content in oil-based ink for ballpoint pens.

Carbon black can be used as the black pigment. For example, Printex 3, 25, 30, 35, 40, 45, 55, 60, 75, 80, 85, 90, 95, 300, Special Black 4, 5, 100, 250, 550 (Degussa Huls Japan Co., Ltd.). Mitsubishi Carbon Black # 2700, # 2650, # 2600, # 2400, # 2350, # 2300, # 2200, # 1000, # 990, # 980, # 970, # 960, Same # 950, Same # 900, Same # 850, Same # 750, Same # 650, Same # 52, Same # 52, Same # 50, Same # 47, Same # 45, Same # 45L, Same # 44, Same # 40, Same # # 33, # 32, # 30, # 25, # 20, # 10, # 5, # 95, # 260, CF9, MCF88, MA600, MA77, MA7, MA11, MA100, MA100R, MA100S, MA100S, MA220, MA230 (above, manufactured by Mitsubishi Chemical Corporation), Talker Black # 8500 / F, # 8300 / F, # 7550SB / F, # 7400, # 736 SB / F, the # 7350 / F, the # 7270SB, the # 7100 / F, the # 7050 (all manufactured by Tokai Carbon Co., Ltd.) and the like.
Examples of blue pigments include C.I. I. Pigment Blue 2, 9, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 16, 17, 28, 29, 36, 60, 68, 76, 80, etc. can be used.
Examples of red pigments include C.I. I. Pigment Red 2, 3, 5, 8, 14, 17, 17, 22, 31, 31, 48: 1, 48: 2, 48: 3, 48: 4, 53 : 1, 53: 2, 57: 1, 112, 122, 144, 146, 149, 166, 170, 175, 176, 177, 179, 184, same 185, 187, 188, 202, 207, 208, 209, 210, 211, 213, 214, 242, 253, 254, 255, 256, 257, 264, 266, 268, 270, 272, etc. can be used.
Examples of yellow pigments include C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 16, 17, 55, 73, 74, 79, 81, 83, 93, 94, 95, the same 97, 109, 110, 111, 120, 128, 133, 136, 138, 139, 147, 151, 154, 155, 167, 173, 174, 175, 176, 180, 185, 191, 194, 213, etc. can be used.
Examples of orange pigments include C.I. I. Pigment Orange 5, 13, 13, 16, 34, 36, 38, 43, 62, 68, 72, 74, and the like.
Examples of green pigments include C.I. I. Pigment Green 7, 36, 37, etc. can be used.
Examples of purple pigments include C.I. I. Pigment Violet 19, 23 and the like can be used.

Examples of dyes include SPILON BLACK GMH SPECIAL, SPILON RED C-GH, SPILON RED C-BH, SPILON BLUE C-RH, SPILON BLUE BPNH, SPILON YELLOW C-2GH, SPILON VIOLET C-RH, S. P. T.A. ORANGE6, S. P. T.A. BLUE111 (made by Hodogaya Chemical Co., Ltd.), etc. VALIFAST BLUE 1601, VALIFAST BLUE 1603, VALIFAST BLUE 1621, VALIFAST BLUE 2601, VALIFAST YELLOW 1110, VALIFAST YELLOW 3104, VALIFAST YELLOW 3105, VALIFAST INDUSTRY Varifast color, orient oil color, rhodamine B base, solder red 3R, methyl violet 2B base, Victoria Blue F4R, etc., and Neo Super Blue C-555 (manufactured by Chuo Synthetic Chemical Co., Ltd.). It is done. These colorants may be used alone or in combination of two or more.
The amount of these dyes to be used is preferably 1% by weight or more and 50% by weight or less, and more preferably 3% by weight or more and 20% by weight or less, based on the total amount of oil-based ink for ballpoint pens. If the amount used is less than 1% by weight, the handwriting is too thin and difficult to read. On the other hand, if it exceeds 50% by weight, the dye may be precipitated.

A copolymer containing at least a monomer having a carboxylic acid group in the molecule and a monomer having a styrene group as a constitutional unit or a polyvinyl butyral resin having a hydroxyl group is a loose network having a moderate space due to hydrogen bonding with both terminal amino-modified silicones. It is used to form a structure and prevent the occurrence of handwriting blur at the beginning of writing.
Specific examples include styrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-maleic anhydride copolymer, methoxyethylene-maleic anhydride copolymer, isobutylene-maleic anhydride. Examples include copolymers and polyvinyl butyral resins. Among them, a copolymer of styrene and acrylic acid or maleic anhydride and polyvinyl butyral are particularly effective and preferable.
Examples of the styrene-maleic acid resin include SMA1000, SMA2000, SMA3000, SMA EF30, SMA EF40, SMA1440, SMA17352, SMA2625, SMA3840 (manufactured by Kawa Crude Chemical Co., Ltd.) and the like. Mwital B20H, B30B, B30H, B60T, such as Jonkrill 678, Jonkrill 586, Jonkrill 611, Jonkrill 680, Jonkrill 682, Jonkrill 683, Jonkrill 690 (manufactured by Johnson Polymer Co., Ltd.) , B60H, B60HH, B70H (manufactured by Hoechst), ESREC B, ESREC BH-3, ESREC BL-1, ESREC BL-2, ESREC BL-L, ESREC B L-S, S-Rec BM-1, S-Rec BM-2, S-Rec BM-5, S-Rec BM-S (manufactured by Sekisui Chemical Co., Ltd.), Denka Butyral # 2000-L, Denka Butyral # 3000-1, Denka Butyral # 3000-2, Denkabutyral # 3000-3, Denkabutyral # 3000-4, Denkabutyral # 3000-K, Denkabutyral # 4000-1, Denkabutyral # 5000-A, Denkabutyral # 6000-C (Electrochemical Industry ( Etc.). These may be used alone or in combination of two or more.
The carboxylic acid group in these copolymers or the hydroxyl group in the polyvinyl butyral resin is preferably present in an acid state rather than as a salt because it is necessary to hydrogen bond with the amino-modified silicone at both ends. Cross-linked polymers and copolymers are not preferred because it is difficult to form a moderate network structure having an appropriate space due to hydrogen bonds with both terminal amino-modified silicones.
The copolymer containing at least a monomer having a carboxylic acid group in the molecule and a monomer having a styrene group as a constituent unit preferably has a weight average molecular weight in the range of 1,000 to 18,000. When the weight average molecular weight is less than 1000, it is difficult to form a moderate network structure having an appropriate space due to hydrogen bonds with both terminal amino-modified silicones, and when it exceeds 18000, the solubility in a solvent is lowered and the dissolution stability with time is reduced. There is a fear of getting worse.
Moreover, it is preferable that the polyvinyl butyral resin which has a hydroxyl group exists in the range whose weight average molecular weight is 10,000 or more and 150,000 or less. When the weight average molecular weight is less than 10,000, it is difficult to form a moderate network structure having an appropriate space due to hydrogen bonds with both terminal amino-modified silicones, and when it exceeds 150,000, the solubility in a solvent is lowered and the dissolution stability with time is reduced. There is a fear of getting worse.
The amount of the copolymer containing at least a monomer having a carboxylic acid group in the molecule and a monomer having a styrene group as a constituent unit or a polyvinyl butyral resin having a hydroxyl group is 0.1% by weight based on the total amount of oil-based ink for ballpoint pens. The amount of 40% by weight or less can be suitably used, and 0.5% by weight or more and 20% by weight or less is more preferable. If the amount used is less than 0.1% by weight, a sufficient amount of network structure cannot be formed. On the other hand, when the amount is more than 40% by weight, a problem that the writing taste becomes heavy tends to occur.

  The organic solvent is a main medium of the ink and can be used without particular limitation as long as it is conventionally used for oil-based ballpoint pens, and glycol ethers, glycols, and alcohols are preferable. Specific examples include phenyl glycol, phenyl dipropylene glycol, 3-methyl-3methoxybutanol, benzyl alcohol, propylene glycol, dipropylene glycol, isobutyl glycol, isobutyl diglycol, hexylene glycol, phenyl diglycol, benzyl glycol Benzyl diglycol, propylene glycol monophenyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monobutyl ether, etc. I can list them. These solvents can be used alone or in combination, and the amount used is preferably 10% by weight or more and 80% by weight or less based on the total amount of the ink.

Both-end amino-modified silicone has a structure in which an alkylamine is bonded to dimethylsiloxane molecules at both ends of polydimethylsiloxane, and has at least a monomer having a carboxylic acid group and a monomer having a styrene group in the molecule as structural units. It is used to form a loose network structure having an appropriate space by hydrogen bonding with a copolymer or a polyvinyl butyral resin having a hydroxyl group, and to prevent the occurrence of handwriting blurring at the beginning of writing.
Examples of both terminal amino-modified silicones include diaminopropyltetramethyldisiloxane and 3-aminopropyl-terminated polydimethylsiloxane.
As a specific example, PAM-E, KF-8010, X-22-161A, X-22-161B, KF-8012, KF-8008, X-22-1660B-3 (manufactured by Shin-Etsu Chemical Co., Ltd.) ), BY16-871, BY16-853C, BY16-853U (manufactured by Toray Dow Corning Co., Ltd.), and the like.
The use amount of these both terminal amino-modified silicones is suitably 0.1% by weight or more and 20% by weight or less, more preferably 0.5% by weight or more and 10% by weight or less, based on the total amount of oil-based ink for ballpoint pens. If the amount used is less than 0.1% by weight, a sufficient amount of network structure cannot be formed. On the other hand, if it exceeds 20% by weight, the amino-modified silicone at both ends will be insoluble.

  Further, even if it is a side chain amino-modified silicone in which alkylamine is bonded to the side chain of polydimethylsiloxane, a copolymer containing at least a monomer having a carboxylic acid group and a monomer having a styrene group in the molecule as a constituent unit, or Hydrogen bonds with a polyvinyl butyral resin having a hydroxyl group to form a network structure, but since the amino group is located in the side chain, the polydimethylsiloxane chain is the main chain of the copolymer or the polyvinyl butyral resin. Since they are bonded in parallel with the chain, it is difficult to form a moderate network structure having an appropriate space, which is not preferable.

  Moreover, since it has only one functional part per molecule of silicone, it is not preferable that it is a one-terminal amino-modified silicone because a network structure cannot be formed.

  Further, when water is present in an amount exceeding 15% by weight, the amino groups of both terminal amino-modified silicones are hydrated, and at least a monomer having a carboxylic acid group in the molecule and a monomer having a styrene group are included in the constituent unit. Hydrogen bonds between the polymer or the polyvinyl butyral resin having a hydroxyl group and the amino-modified silicone at both ends are not formed. Therefore, the water content is desirably 15% by weight or less, preferably 10.0% by weight or less, and more preferably 5.0% by weight or less.

In addition to the above ingredients, lubricants and viscosity modifiers, shear thinning agents, rust preventives, antiseptics, antifoaming agents, anti-scratch agents, dispersants, stringers used as ink raw materials for oil-based ballpoint pens as necessary It is also possible to use additives such as a property-imparting agent and leveling property-imparting agent in combination.
Lubricants are used to give smooth writing, but cutting oils, higher fatty acids, phosphate esters, acylamino acids, and thiazoles are generally used.

  As the viscosity modifier, polyvinyl pyrrolidone, ketone resin or the like is preferably used, and those soluble or dispersed in one of the organic solvents can be used, but soluble ones are preferred.

Examples of shear thinning agents include cellulose derivatives such as hydroxypropylcellulose, hydroxyethylcellulose, ethylhydroxyethylcellulose, ethylcellulose, water-soluble polysaccharides such as hyaluronic acid, silicic anhydride, hydrous silicic acid, hydrous silicic acid metal salts, aluminum oxide , Zinc oxide, metal phosphate calcium phosphate, metal phosphate iron phosphate, manganese hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, basic magnesium carbonate, dessant, nacrite, cutisotile, antigora, hematite, magnetite , Ferrite, barium ferrite, mullite, zirconia, lithopone, talc, clay, kaolinite, halosite, muscovite, phlogopite, biotite, pyroferrite, vermiculite, montmorillonite, Inorganic such as psitet, boehmite, cristobalite, crystallite, beidellite, tellurite, laterite, jewelite, zeolite, celite, bentonite, chlorite, sericite, allophane, smectite, hydrotalcite, silica sand, carbon black, graphite Compound, poly-N-vinylacetamide, cross-linked poly-N-vinylacetamide, poly-N-isopropylacrylamide, a polymer of acrylic acid or methacrylic acid or a copolymer thereof with an alkyl ester, and a cross-linked product of these are also used. Is possible.
Of these, cellulose derivatives are particularly preferred because of their high shear thinning. Of these, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, and the like, which have good solubility characteristics and viscosity characteristics, are preferable. The amount of the shear thinning agent used can be 0.02% by weight or more and 3.0% by weight or less, preferably 0.02% by weight or more and 2.0% by weight or less based on the total amount of oil-based ink for ballpoint pens. If the amount is less than 0.02% by weight, sufficient shear thinning cannot be imparted to the ball-point pen oil-based ink. If the amount is more than 3.0% by weight, the viscosity of the ball-point pen oil-based ink becomes too high and the fluidity is reduced. Since the character becomes worse, the writing taste becomes heavier and the wrinkle of the writing line becomes larger.
In addition, when shear thinning is applied, the purpose is to make writing quality lighter by preventing leakage of ink for ballpoint pens when the pen tip is left facing down and by making the viscosity decrease during writing optimal. And the shear thinning index at 25 ° C. must be 0.3 or more and 0.9 or less.

In the case of using a pigment in the present invention, it is usually possible to disperse the pigment by a general method. For example, a pigment, an organic solvent, and a dispersant are mixed and stirred uniformly with a propeller stirrer or the like, and then the pigment is dispersed with a disperser. A dispersing machine such as a roll mill, a ball mill, a sand mill, a bead mill, or a homogenizer is appropriately selected depending on the amount of solvent of the ink and the pigment concentration.
In order to produce an ink, the above-described pigment, a copolymer containing at least a monomer having a carboxylic acid group in the molecule, a terminal amino-modified silicone, and other components such as a viscosity modifier, a solvent, a color tone It is obtained by mixing oil-based dyes, lubricants, etc. for adjustment, and dissolving and mixing until uniform with a stirrer such as a homomixer. The obtained ink may be filtered or centrifuged to remove coarse particles and insoluble components.
Further, the viscosity of the ink of the present invention is 500 to 100,000 mPa · s, 10 / s when the shear rate is 1 / s in consideration of ink discharge and ink leakage from the pen point when the pen point is left facing down. In this case, 300 to 1500 mPa · s is preferable.

  Hereinafter, it demonstrates still in detail based on an Example and a comparative example. In each example, “part” simply means “part by weight”.

(Example 1)
Special Black 4 (carbon black, manufactured by Degussa Huls Japan Co., Ltd.)
15.0 parts benzyl glycol 50.5 parts isobutyl diglycol 16.8 parts ESREC BL-1 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) 9.2 parts ESREC BH-3 (polyvinyl butyral, Sekisui Chemical Co., Ltd.) )) 0.5 part SK resin (ketone resin, manufactured by Degussa Japan Co., Ltd.) 8.0 parts X22-161A (both ends amino-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd.) 2.0 parts Among them, 6.0 parts of S-Rec BL-1, 30.0 parts of benzyl glycol, and 10.0 parts of isobutyl diglycol were heated and stirred at about 70 ° C. and uniformly dissolved, and then the total amount of Special Black 4 was added. Mix evenly. This was allowed to cool to room temperature and then passed 10 times with a three roll mill to obtain a red paste. Next, 3.2 parts of ESREC BL-1, and all of ESREC BH-3 and SK resin were added to 20.5 parts of benzyl glycol and 6.8 parts of isobutyl diglycol, and heated at about 70 ° C. using a propeller stirrer. The total amount of X22-161A was added to the stirred and uniformly dissolved solution, and further stirred for 1 hour to uniformly dissolve. Then, add the entire amount of black paste to this, mix and stir for 2 hours until it becomes uniform at about 70 ° C., press filter with filter paper (5A, manufactured by Toyo Filter Paper Co., Ltd.), and red oil ink for ballpoint pens. Got. The viscosity of this ink was 2910 mPa · s at a shear rate of 1 / s at 6200 mPa · s and at 10 / s.

(Example 2)
NOVOPERM RED F3RK 70 (CI Pigment Red 170, Clariant Japan Co., Ltd.) 4.0 parts benzyl glycol 48.2 parts isobutyl diglycol 16.1 parts ESREC BL-1 (polyvinyl butyral, Sekisui Chemical Co., Ltd.) )) 5.2 parts ESREC BH-3 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) 0.5 parts SK resin (ketone resin, manufactured by Degussa Huls Japan Co., Ltd.) 8.0 parts Eisen Spiron YELLOW C -GNH (dye, manufactured by Hodogaya Chemical Co., Ltd.) 4.1 parts Eisen Spiron RED C-BH (dye, manufactured by Hodogaya Chemical Co., Ltd.) 5.2 parts Eisen Spiron RED C-GH (dye, Hodogaya Chemical) 6.7 parts X22-161A (both ends amino-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.0 part Of the above components, 2.0 parts of ESREC BL-1, 10.0 parts of benzyl glycol, and 3.5 parts of isobutyl diglycol were heated and stirred at about 70 ° C. and uniformly dissolved, then NOVOPER RED The whole amount of F3RK 70 was added and mixed uniformly. This was allowed to cool to room temperature and then passed 10 times with a three roll mill to obtain a red paste. Next, 3.2 parts of ESREC BL-1, and the total amount of ESREC BH-3 and SK resin were added to 38.2 parts of benzyl glycol and 12.6 parts of isobutyl diglycol, and heated at about 70 ° C. using a propeller stirrer. The total amount of Eisen spiron YELLOW C-GNH, Eisen spirone RED C-BH, Eisen spirone RED C-GH, and X22-161A was added to the stirred and uniformly dissolved solution, and the mixture was further stirred for 1 hour to uniformly dissolve. Add the whole amount of red paste to this, mix and stir for 2 hours until it becomes uniform at about 70 ° C., press filter with filter paper (5A, manufactured by Toyo Filter Paper Co., Ltd.), and red oil ink for ballpoint pen. Got. The viscosity of this ink was 3060 mPa · s at a shear rate of 1 / s and 6140 mPa · s at 10 / s.

(Example 3)
HOSTAPERM BLUE B2G-D (CI Pigment Blue 15: 1, manufactured by Clariant Japan Co., Ltd.) 15.0 parts benzyl glycol 59.4 parts isobutyl diglycol 19.8 parts Jonkrill 678 (styrene-acrylic acid copolymer) , Weight average molecular weight 8500, manufactured by BASF Japan Ltd.) 3.5 parts Crucell H (hydroxypropylcellulose, shear thinning agent, manufactured by Sanki Co., Ltd.)
0.3 part BY16-853U (both end amino-modified silicone, manufactured by Toray Dow Corning Co., Ltd.)
2.0 parts Among the above components, the total amount of Joncrill 678, 30.0 parts of benzyl glycol, and 10.0 parts of isobutyl diglycol were heated and stirred at about 70 ° C. and dissolved uniformly, and then HOSTAPER BLUE B2G- The whole amount of D was added and mixed uniformly. This was allowed to cool to room temperature and then passed 10 times with a three roll mill to obtain a blue paste. Next, the total amount of Crucell H is added to 29.4 parts of benzyl glycol and 9.8 parts of isobutyl diglycol, and the total amount of BY16-853U is added to the liquid that is uniformly dissolved by heating and stirring at about 70 ° C. using a propeller stirrer. Furthermore, it stirred for 1 hour and melt | dissolved uniformly. Then, the whole amount of blue paste is added to this, mixed and stirred for 2 hours until it becomes uniform at about 70 ° C., pressure filtered using filter paper (5A, manufactured by Toyo Filter Paper Co., Ltd.), and black oil-based ink for ballpoint pens. Got. The viscosity of this ink was 1780 mPa · s at a shear rate of 1 / s and 860 mPa · s at 10 / s.

Example 4
Special Black 4 (carbon black, manufactured by Degussa Huls Japan Co., Ltd.) 5.0 parts benzyl glycol 45.2 parts isobutyl diglycol 15.1 parts Jonkrill 678 (styrene-acrylic acid copolymer, weight average molecular weight 8500, BASF Japan Co., Ltd.) 0.3 parts Jonkrill 682 (styrene-acrylic acid copolymer, weight average molecular weight 1700, BASF Japan Co., Ltd.) 0.7 parts Eisen Spiron YELLOW C-GNH (dye, Hodogaya) Chemical Co., Ltd.) 2.5 parts Eisen Spiron RED C-BH (dye, Hodogaya Chemical Co., Ltd.) 3.7 parts Neo Super Blue C-555 (dye, Chuo Synthetic Chemical Co., Ltd.) 13. 8 parts ESREC BL-1 (polyvinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) 3.2 parts ESREC BH-3 (Po Vinyl butyral, manufactured by Sekisui Chemical Co., Ltd.) 0.5 parts SK resin (ketone resin, manufactured by Degussa Huls Japan Co., Ltd.) 8.0 parts X22-161A (both ends amino-modified silicone, Shin-Etsu Chemical Co., Ltd.) 2.0 parts Among the above components, the total amount of Jonkrill 678 and Jonkrill 682, 15.0 parts of benzyl glycol, and 5.0 parts of isobutyl diglycol are heated and stirred at about 70 ° C. and dissolved uniformly. After that, all the special black 4 was added and mixed uniformly. This was allowed to cool to room temperature and then passed 10 times with a three roll mill to obtain a black paste. Next, the total amount of ESREC BL-1, ESREC BH-3 and SK resin was added to 29.9 parts of benzyl glycol and 9.9 parts of isobutyl diglycol, and the mixture was uniformly dissolved by heating and stirring at about 70 ° C. using a propeller stirrer. The total amount of Eisen Spiron YELLOW C-GNH, Eisen Spiron RED C-BH, Neo Super Blue C-555 and X22-161A was added to the solution, and the mixture was further stirred for 1 hour to uniformly dissolve. Then add the whole amount of black paste to this, mix and stir for 2 hours until it becomes uniform at about 70 ° C., and filter with pressure using filter paper (5A, manufactured by Toyo Filter Co., Ltd.). Got. The viscosity of this ink was 6300 mPa · s at a shear rate of 1 / s and 4300 mPa · s at 10 / s.

(Example 5)
In Example 2, red oil-based ink for ballpoint pens was obtained in the same manner except for adding 6.7 parts of benzyl glycol and 9.0 parts of ion-exchanged water instead of 2.3 parts of isobutyl diglycol. The viscosity of this ink was 1130 mPa · s at a shear rate of 1 / s and 2020 mPa · s at 10 / s.

(Comparative Example 1)
A black ballpoint pen-based oil-based ink was obtained in the same manner as in Example 1 except that benzyl glycol was added instead of X22-161A. The viscosity of the ink was 2360 mPa · s at 3900 mPa · s at a shear rate of 1 / s and 10 / s.

(Comparative Example 2)
In Example 2, red oil-based ink for ballpoint pens was obtained in the same manner except that benzyl glycol was added instead of X22-161A. The viscosity of this ink was 2220 mPa · s at 4050 mPa · s at a shear rate of 1 / s and 10 / s.

(Comparative Example 3)
In Example 3, blue oil-based ink for ballpoint pens was obtained in the same manner except that benzyl glycol was added instead of BY16-853U. The viscosity of this ink was 1720 mPa · s at a shear rate of 1 / s and 780 mPa · s at 10 / s.

(Comparative Example 4)
In Example 4, black oil-based ink for ballpoint pens was obtained in the same manner except that benzyl glycol was added instead of X22-161A. The viscosity of this ink was 2690 mPa · s at a shear rate of 1 / s and 1620 mPa · s at 10 / s.

(Comparative Example 5)
A black ballpoint pen oil-based ink was obtained in the same manner as in Example 1 except that KF-865 (side chain amino-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd.) was added instead of X22-161A. The viscosity of this ink was 1500 mPa · s at a shear rate of 1 / s at 2240 mPa · s and at 10 / s.

(Comparative Example 6)
In Example 2, red oil-based ink for ballpoint pens was obtained in the same manner except that KF-865 (side chain amino-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd.) was added instead of X22-161A. The viscosity of the ink was 1620 mPa · s at 2500 mPa · s at a shear rate of 1 / s and 10 / s.

(Comparative Example 7)
In Example 3, a blue ballpoint pen oil-based ink was obtained in the same manner except that BY16-890 (side chain amino-modified silicone, manufactured by Toray Dow Corning Co., Ltd.) was added instead of BY16-853U. The viscosity of this ink was 1720 mPa · s at a shear rate of 1 / s and 780 mPa · s at 10 / s.

(Comparative Example 8)
In Example 4, black oil-based ink for ballpoint pens was obtained in the same manner except that KF-865 (side chain amino-modified silicone, manufactured by Shin-Etsu Chemical Co., Ltd.) was added instead of X22-161A. The viscosity of this ink was 2980 mPa · s at a shear rate of 1 / s and 1810 mPa · s at 10 / s.

(Comparative Example 9)
In Example 1, 4.5 parts of K90 (polyvinyl pyrrolidone, manufactured by IPS Japan Co., Ltd.) is added instead of 4.5 parts of S-REC BL-1, and 4.7 parts of S-REC BL-1 are added. A black oil-based ink for ballpoint pens was obtained in the same manner except that 5.2 parts of benzyl glycol was added in place of 0.5 parts of SREC BH-3. The viscosity of this ink was 3370 mPa · s at a shear rate of 1 / s at 6120 mPa · s and at 10 / s.

(Comparative Example 10)
In Example 2, Gantrez AN-119 (methyl vinyl ether / maleic anhydride copolymer, manufactured by ASP Japan Co., Ltd.) was added in place of S-Rec BL-1, and benzyl glycol was used in place of S-Rec BH-3. Except for the addition, red oil-based ink for ballpoint pens was obtained in the same manner. The viscosity of this ink was 2100 mPa · s at 4890 mPa · s at a shear rate of 1 / s and 10 / s.

(Comparative Example 11)
In Example 3, black oil-based ink for ballpoint pens was obtained in the same manner except that Decaglyn 1-O (decaglyceryl monooleate, manufactured by Nikko Chemicals Co., Ltd.) was added instead of Joncrill 678. The viscosity of this ink was 1890 mPa · s at 4450 mPa · s at a shear rate of 1 / s and 10 / s.

(Comparative Example 12)
In Example 2, red oil-based ink for ballpoint pens was obtained in the same manner except that 12.0 parts of benzyl glycol and 4.0 parts of isobutyl diglycol were added instead of 16.0 parts of ion-exchanged water. The viscosity of this ink was 1010 mPa · s at a shear rate of 1 / s at 1890 mPa · s and at 10 / s.

As mentioned above, the following test was done about the ink composition obtained by the Example and the comparative example. The results are shown in Table 1.
The viscosity was measured by attaching a 40-diameter parallel rotor to a rheometer VAR-100 manufactured by Jusco International Co., Ltd., adjusting the gap between the sample stage to 0.8 mm, and adjusting the shear rate to 1 at a constant speed. / S was performed at 25 ° C.

(Preparation of test ballpoint pen)
0.3 g of the oil-based ballpoint pen ink obtained in the above Examples and Comparative Examples was applied to a writing instrument having the same structure as a commercially available oil-based ballpoint pen (.e-ball, product code BK127, manufactured by Pentel Co., Ltd. (ball diameter φ0.7)). After filling, a centrifugal force was applied with a centrifuge to degas bubbles in the ink, and a test ballpoint pen was produced.

Initial writing property: A straight line of 30 cm was written at a load of 150 g, a writing speed of 7 cm / sec and a writing angle of 70 ° in a constant temperature room at 25 ° C. and 65 ± 5%, and the shading length of the drawn line at the beginning of writing was measured. The conditions are as follows.
Initial test: Written immediately after ink filling.
Heating accelerated test: After being left in a constant temperature bath at a temperature of 50 ° C. and a humidity of 30% for 7 days, it was transferred to a constant temperature room at 25 ° C. and 65 ± 5% and immediately written.

  As described above in detail, the ink of the present invention relates to an oil-based ink for ballpoint pens that can be smoothly written without blurring of handwriting at the time of writing even after long-term storage.

Claims (1)

Contains at least a coloring agent, an organic solvent, a copolymer containing at least a monomer having a carboxylic acid group in the molecule and a monomer having a styrene group as a constituent unit or a polyvinyl butyral resin having a hydroxyl group, and an amino-modified silicone at both ends Oil-based ink for ballpoint pens.