JP3004062B2 - Inks and colorants for inks - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink used for a writing instrument, a stamp, a printing, an ink jet, a recorder, and the like, and a colorant for the ink. More specifically, the present invention provides an ink in which carbon black is uniformly dispersed, has an appropriate viscosity and has good writability, and has good dispersibility in a dispersion medium and when dispersed in a dispersion medium. The present invention relates to a colorant for an ink which can impart an appropriate viscosity to the ink.

[0002]

2. Description of the Related Art Carbon black is widely used as a black colorant in the field of inks and coatings, and inks using such carbon black exhibit good properties such as water resistance and stability over time. It is. However, carbon black has a weaker affinity with other substances, such as organic polymers, water and organic solvents, than the cohesive force between particles. In general, it is necessary to use a refining and dispersing apparatus such as a roll mill or a ball mill and consume a large amount of energy to loosen the structure and secondary agglomeration of carbon black. Further, it is common to use a dispersant such as a surfactant or a water-soluble polymer to assist dispersion and prevent sedimentation or aggregation during storage as an ink or paint, but dispersibility can be sufficiently satisfied even by using this method. Not a thing,
In addition, the dispersant used tends to lower the performance of inks and paints.

In order to overcome such disadvantages, for example, Japanese Patent Publication Nos. 4222047 and 44-3826,
JP-B-45-17284, U.S. Pat. No. 3,557,040
It is proposed to use a carbon black graft polymer obtained by polymerizing a polymerizable monomer in the presence of carbon black. According to such a method, the hydrophilicity and / or lipophilicity of the carbon black graft polymer obtained by appropriately selecting the type of the polymerizable monomer can be appropriately changed, so Can be expected to improve dispersibility. However, the yield of the carbon black graft polymer obtained by the method disclosed in the above-mentioned literature is as low as several% to several tens%, and most of the carbon black graft polymer exists in the form of a vinyl homopolymer, and the surface treatment efficiency of the carbon black is high. Is extremely poor, so that the affinity with other substances was not improved as expected, and the dispersion state often varied depending on the mixing or dispersion conditions.

Further, in JP-A-63-265913 and JP-A-1-79278, a carbon black graft polymer is obtained by reacting carbon black with a polymer having reactivity with the carbon black under specific conditions. Thus, the carbon black graft polymer thus obtained was rich in affinity for water and organic solvents, and exhibited excellent dispersibility in these media. However, although this dispersion can be suitably used as a pigment paste for toning of inks, paints, plastics, and the like, when this dispersion itself is used as an ink, particularly an aqueous ink, the ink viscosity becomes too high, and it is used for writing implements and the like. When used, the ink comes out from the pen tip, and ink bleeding or handwriting bleeding or strike-through becomes remarkable, and when used for inkjet, the ink particle diameter cannot be controlled.

[0005]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel ink used for a writing instrument, a stamp, a printing, an ink jet, a recorder, and the like. Another object of the present invention is an ink containing carbon black as a coloring agent, wherein the carbon black is uniformly finely dispersed in a dispersion medium and has an appropriate viscosity for its use. It is intended to provide. Still another object of the present invention is to provide a colorant for ink which has improved dispersibility of carbon black in a dispersion medium and has good viscosity characteristics.

[0006]

SUMMARY OF THE INVENTION The above objects are as follows.
100 parts by weight of carbon black and general formula (A)

[0007]

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(Wherein R is a C ₁ -C ₃₀ alkyl group, aryl group, alkylaryl group, or halogenated aryl group, n = 1-50, and R
Is the ratio of the number of carbon atoms Cm to the total number of ethylene oxide units n,
0.02 <Cm / n <5 is satisfied. ), A number
Compounds 5 to 200 having an average molecular weight of 150 to 2000
Of a treated carbon black obtained by heating and mixing the ink colorant at 50 ° C. to 350 ° C. and an ink obtained by dispersing the ink colorant in a dispersion medium. .

The carbon black used in the present invention has carboxyl groups and / or
Or any one having a hydroxyl group, for example, any type of furnace black, channel black, acetylene black, lamp black and the like can be used. Considering the reactivity of the compound represented by the formula (1) with the epoxy group which is a terminal reactive group, the carbon black preferably has a pH of 8 or less, preferably 6 or less. That is, when the pH of the carbon black is extremely high, the reactivity with the epoxy group decreases. The test method for the pH of carbon black is JIS
K 6211.

On the other hand, such a compound to be grafted onto carbon black is represented by the general formula (A).

[0011]

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In the general formula (A), R represents C ₁ to
C ₃₀ , an aryl group, an alkylaryl group, or a halogenated aryl group, of which a C ₆ -C ₂₀ straight-chain or branched-chain alkyl group such as dodecyl and tridecyl, for example, phenyl, naphthyl and the like are preferable. halogenated having an aryl group, p-dodecylphenyl, alkylaryl group C ₄ -C _20, such as para-tertiary butyl phenyl, chlorophenyl, dichlorophenyl, bromophenyl, dibromophenyl, 1-4 halogen substituents, such as bromine chlorophenyl An aryl group,
More preferably, it is a C ₆ -C ₂₀ linear or branched alkyl group. In the general formula (A), the number of repetitions n of ethylene oxide (— (CH ₂ CH ₂ O) —) is 1 to 5
0, but more preferably 5 to 30. Further, the ratio of the carbon number Cm of R to the total number n of ethylene oxide molecules in the general formula (A) is 0.02 <Cm / n <5, more preferably 0.2 <Cm / n <3. Is desired. That is, if Cm / n is less than 0.02, the water resistance of the ink according to the present invention may not be sufficient, while if Cm / n exceeds 5, the dispersion of the treated carbon black obtained may be insufficient. There is a great risk that the performance will be reduced. Further, it is desired that the number average molecular weight of the polymer represented by the general formula (A) is about 150 to 2,000, more preferably about 300 to 1500. That is, when the number average molecular weight of the polymer represented by the general formula (A) is less than 150, even if such a polymer is grafted, the dispersibility of carbon black cannot be sufficiently improved. When the number average molecular weight exceeds 2,000, the viscosity of the ink according to the present invention increases, and the ink is not suitable for writing instruments, stamps, printing, ink jets, recorders, and the like. This is because there is a fear.

Preferred examples of the polymer represented by the general formula (A) include, for example, lauryl alcohol (ethylene oxide) ₁₅ glycidyl ether and phenol (ethylene oxide) ₅ glycidyl ether.

The colorant for an ink of the present invention is obtained by adding the compound represented by the general formula (A) as described above to carbon black.
It is composed of a treated carbon black obtained by heating and mixing at a temperature of 0 to 350 ° C, more preferably 100 to 200 ° C. If the treatment temperature condition is higher than 350 ° C., the compound represented by the general formula (A) is likely to deteriorate, while if the treatment temperature condition is lower than 50 ° C., a sufficient reaction cannot be caused. The graft ratio of the compound to carbon black is lowered, and the cohesiveness of carbon black cannot be improved.

Further, in the colorant for ink of the present invention,
The ratio of the carbon black to the compound represented by the general formula (A) is 5 to 200 parts by weight of the compound represented by the general formula (A) based on 100 parts by weight of the carbon black. That is, when the amount of the compound represented by the general formula (A) is less than 5 parts by weight based on 100 parts by weight of the carbon black, the dispersibility of the treated carbon black in a dispersion medium is insufficient. If the amount exceeds 200 parts by weight, the viscosity of the ink obtained when the amount of carbon black in the ink is adjusted to an optimum amount becomes high, and the versatility becomes poor.

At the time of this reaction, it is desirable to carry out stirring and mixing, whereby the carbon black in a secondary agglomerated state used as a raw material is efficiently pulverized when mixed and reacted to produce fine and fine particles. It has a uniform particle size,
In addition, since the efficiency of the reaction is improved, the characteristics of the obtained treated carbon black are further enhanced. Further, this stirring and mixing is performed by mixing the carbon black and the polymer represented by the general formula (A) with a torque value of 0.1 to 20 kg.
m, more preferably in the range of 0.3 to 10 kg · m.

In the production of the treated carbon black used as the colorant for the ink of the present invention, the heating and mixing for causing the reaction between the carbon black and the compound represented by the general formula (A) involves heating and mixing only these two components. Or a polymer other than the compound represented by the general formula (A),
Polymerizable monomer, organic solvent, may be a method of heating and mixing under the mixture of other substances such as water, but considering the viscosity of the ink when the ink goes into a smooth process and ink,
A method of heating and mixing in the presence of a water-soluble polymer other than the compound represented by the general formula (A) is preferable. Examples of such a water-soluble polymer include nonionic surfactants such as polyethylene glycol, polypropylene glycol, polyvinyl alcohol, polyoxyalkylphenol ether, and polyoxyethylene fatty acid ester, and sodium salts of β-naphthalene sulfonate formaldehyde condensate. And anionic surfactants such as sodium ligninsulfonate, and polyethylene glycol is most preferable from the combined effect with the compound represented by the general formula (A). In addition, the molecular weight of these water-soluble polymers is 150 to 10,000 in consideration of the viscosity of the ink.
0, more preferably 150 to 1,000. As an example specifically showing an embodiment of the method for producing the treated carbon black contained in the ink of the present invention, for example, 5 to 200 parts by weight of the polymer represented by the general formula (A) based on 100 parts by weight of carbon black Parts, preferably 10 to 100 parts by weight, 0 to 200 parts by weight of a water-soluble polymer other than the polymer represented by the general formula (A), preferably 5 to 5 parts by weight.
A mixture obtained by mixing 200 parts by weight, 0 to 200 parts by weight of a polymerizable monomer, and 0 to 200 parts by weight of an organic solvent or water is stirred and mixed at a temperature of 50 to 350 ° C.

The treated carbon black thus obtained is obtained by reacting the compound represented by the general formula (A) with the carbon black, and the epoxy group, which is a reactive group in the compound, is applied to the surface of the carbon black. Since the compound has high reactivity with a functional group, the compound is grafted onto the surface of carbon black with high efficiency. For this reason, the obtained treated carbon black has improved affinity with various substances, for example, has excellent dispersibility in organic polymers, water, organic solvents, and the like, and particularly has excellent dispersibility in water. Because it is remarkably excellent and has good lubricity,
It exhibits an appropriate viscosity when dispersed in various dispersion media, and can be suitably used as a coloring agent for inks, particularly water-soluble inks. It is very easy to disperse the treated carbon black in the dispersion medium, and it is not necessary to apply a high shearing force for the dispersion, and the treated carbon black and water and / or an organic solvent, such as a propeller blade, are added at room temperature or under heating. It can be dispersed in a dispersion medium simply by stirring with a stirrer equipped with a paddle-shaped blade. In addition, when the heating and mixing of the carbon black and the compound represented by the general formula (A) are performed in the presence of water and / or an organic solvent, the treated carbon black is obtained as a dispersion. It can be used, and the amount of the treated carbon black to the dispersion medium can be adjusted as needed.

The ink of the present invention is obtained by dispersing a treated carbon black obtained by reacting the compound represented by the general formula (A) with carbon black as described above in a dispersion medium. The amount of the black in the dispersion medium depends on the type of the dispersion medium used.
The content of 50% by weight, more preferably 3 to 30% by weight, provides good writability, does not cause bleeding or strike-through on paper quality, and provides good ink output for a long period of time. desirable.

As the dispersion medium used in the ink of the present invention, water, an organic solvent or a mixture of water and an organic solvent can be used. Of these, water, ethylene glycol, diethylene glycol and triethylene glycol are preferred. , Glycol solvents such as propylene glycol and 1,8-butylene glycol, glycol ether solvents such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate and ethylene glycol monoethyl ether acetate Glycol ether ester solvents such as glycerin, 2-pyrrolidone and N-
Pyrrolidone solvents such as methyl-2-pyrrolidone, amino alcohol solvents such as triethanolamine, diethanolamine and monoethanolamine, and water-soluble organic solvents such as sulfolane, or a mixture of water and these water-soluble organic solvents. And especially water and a mixture of water and a water-soluble organic solvent. When water-soluble organic solvents as described above are used in addition to water as a dispersion medium, these water-soluble organic solvents function as an evaporation inhibitor, so that the storage stability of the ink over time and the non-evaporation property can be expected. The ratio of these water-soluble organic solvents to water is
Water 10 depends on the type of water-soluble organic solvent.
The amount is 70 parts by weight or less, more preferably 5 to 60 parts by weight, based on 0 parts by weight of the water-soluble organic solvent. That is, water 100
If the amount of the water-soluble organic solvent exceeds 100 parts by weight with respect to the parts by weight, the viscosity of the obtained ink will be excessively increased, resulting in poor ink ejection, or marked blurring or strike-through of the handwriting. This is because there is a high risk of occurrence.

In the ink of the present invention, in addition to the above-described treated carbon black and dispersion medium, various known additives can be further added as necessary. Examples of the additive include nonionic surfactants such as polyethylene glycol, polyoxyalkylphenol ether, and polyoxyethylene fatty acid ester, and β.
-Lubricants such as sodium salts of naphthalene sulfonate formaldehyde condensate, anionic surfactants such as sodium lignin sulfonate, silicone resins, phosphate esters, fluorine surfactants, dithiophosphates, dithiocarbamic acid derivatives and molybdates Fungicides such as sodium benzoate and sodium dihydroacetate; rust preventives such as dialkylthiourea, benzotriazole or phosphate; preservatives such as phenol and 1,2-benzisothiazolin-3-one; dextrin and sorbitol. Examples of such a saccharide viscosity-imparting agent, a pen tip drying inhibitor such as urea or a urea derivative, and a pH adjuster such as sodium carbonate and ethanolamines.

[0022]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples. In the following examples, "parts" indicates parts by weight.

Example 1 Carbon black MA-100 (Mitsubishi Kasei Kogyo Co., Ltd.)
100 parts) and Denacol EX-171 (manufactured by Nagase Kasei Kogyo Co., Ltd., lauryl alcohol (ethylene oxide))
25 parts of ₁₅ glycidyl ether) and PEG 200 (manufactured by Sanyo Chemical Industries, Ltd.)
5)) 75 parts and Labo Plastomill (Toyo Seiki Co., Ltd.)
Was kneaded under the conditions of 150 ° C. and 100 rpm for 15 minutes, and cooled to obtain treated carbon (1). Treated carbon (1) 10 parts Propylene glycol 10 parts Ethylene glycol 20 parts Water 60 parts And the treated carbon (1) thus obtained
Was mixed with the dispersing medium in the above mixing ratio and dispersed with a stirrer to prepare an aqueous ink. The particle size of carbon black in the obtained ink was measured by a centrifugal sedimentation method and found to be about 0.03 μm. When this was used as an ink for a water-based felt-tip pen, there were no defects such as blurred handwriting even after writing 3000 characters, and the water resistance was excellent.
There was no change in quality even after several months of standing, indicating good writability.

Comparative Example 1 An aqueous ink was prepared in the same manner as in Example 1, except that 5 parts of untreated carbon black MA-100 was used instead of 10 parts of the treated carbon (1). The particle size of carbon black in the obtained ink was measured by a centrifugal sedimentation method and found to be 5.0 μm. The dispersion was unstable and some carbon black precipitated immediately. In a writing test using this as an aqueous ink for a felt-tip pen, handwriting was blurred.

Example 2 Carbon black MA-100R (Mitsubishi Chemical Industry Co., Ltd.)
100 parts) and 50 parts of Denacol EX-145 (manufactured by Nagase Kasei Kogyo Co., Ltd., phenol (ethylene oxide) ₅ glycidyl ether) and PEG 400 (manufactured by Sanyo Kasei Kogyo Co., Ltd., polyethylene glycol (degree of polymerization 7 to 8))
50 parts were kneaded using a Labo Plastomill (manufactured by Toyo Seiki Co., Ltd.) at 160 ° C. and 100 rpm for 15 minutes, and then cooled to obtain a treated carbon (2). Treated carbon (2) 21 parts Diethylene glycol 20 parts PEG200 10 parts Water 60 parts And the treated carbon (1) thus obtained
Was mixed with the dispersing medium in the above mixing ratio and dispersed with a stirrer to prepare an aqueous ink. The particle size of carbon black in the obtained ink was measured by a centrifugal sedimentation method and found to be about 0.02 μm. When this was used as an ink for ink-jet printing, an extremely clear printed image without clogging and without blurring was obtained.

[0026]

As described above, the ink of the present invention is represented by the formula (A) with 100 parts by weight of carbon black.
Compounds 5 to 20 having a number average molecular weight of 150 to 2000
0 parts by weight are reacted under a temperature condition of 50 ° C. to 350 ° C. to obtain a treated carbon black dispersed in a dispersion medium, and the treated carbon black is represented by the general formula (A). The polymer is efficiently and firmly bonded to the surface of the carbon black, the surface characteristics of the carbon black are modified, and it has good affinity for various dispersion media used, especially aqueous dispersion media, and at the same time has good lubricity , Carbon black is uniformly and micro-dispersed in the ink of the present invention, and has an appropriate viscosity. Therefore, the ink according to the present invention, particularly the water-based ink, has no ink spots or blurred handwriting, and has a good writing property because smooth ink can be obtained over a long period of time. Further, even when used in an ink jet, it is easy to control the ink particle diameter, and furthermore, it has properties such as good water resistance, coloring properties, and stability over time due to the use of carbon black as a coloring agent. For writing instruments, stamps, printing,
It is suitable for inkjet, recorder, and the like. Further, the treated carbon black is one which is remarkably improved in that the carbon black has a low dispersibility in a dispersion medium, and has a good viscosity characteristic, and thus is suitably provided as an ink colorant. It is.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-64-79278 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 11/00-11/20 C09C 1 / 48-1/60

Claims (7)

(57) [Claims] 1. 100 parts by weight of carbon black and the general formula (A) (Wherein, R is a C ₁ -C ₃₀ alkyl group, an aryl group, an alkylaryl group, or a halogenated aryl group, n is 1 to 50, and the carbon number of R is Cm
And the total number n of ethylene oxide units is 0.02 <Cm
/ N <5 is satisfied. ), Having a number average molecular weight of 1
5 to 200 parts by weight of a compound which is 50 to 2000
An ink obtained by dispersing a treated carbon black obtained by heating and mixing under a temperature condition of from C to 350C in a dispersion medium. 2. The method according to claim 1, wherein the treated carbon black has an ink composition of 1 to 3.
The ink according to claim 1 , which is contained at 50% by weight. 3. The ink according to claim 1, wherein the dispersion medium is water, a water-soluble organic solvent, or a mixture of water and a water-soluble organic solvent. 4. The ink according to claim 1 , wherein the dispersion medium is water. 5. The treated carbon black is obtained by heating and mixing in the presence of a water-soluble polymer in addition to carbon black and the compound represented by the general formula (A). The ink according to any one of the above. 6. 100 parts by weight of carbon black and the general formula (A) (Wherein, R is a C ₁ -C ₃₀ alkyl group, an aryl group, an alkylaryl group, or a halogenated aryl group, n is 1 to 50, and the carbon number of R is Cm
And the total number n of ethylene oxide units is 0.02 <Cm
/ N <5 is satisfied . ), Having a number average molecular weight of 1
5 to 200 parts by weight of a compound which is 50 to 2000
A colorant for an ink comprising a treated carbon black obtained by heating and mixing under a temperature condition of from 0 ° C to 350 ° C. 7. The treated carbon black according to claim 6 , which is obtained by heating and mixing in the presence of a water-soluble polymer in addition to the carbon black and the compound represented by the general formula (A). Colorant for ink.