JPH0122314B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to colored polymer-based aqueous ink compositions. More specifically, the present invention relates to an aqueous ink composition comprising a colored polymer obtained by dyeing a water-soluble polymer containing a hydroxyl group and a sulfonic acid group with a basic dye and a water-soluble organic solvent. Conventionally, water-based inks have been known in which water-based dyes, such as direct dyes, acid dyes, and basic dyes, are dissolved in water, and wetting agents, preservatives, etc. are added. Therefore, the recorded ink easily dissolves when it comes into contact with water or a damp object, causing the printed area to smear and become smudged or unclear, and has the drawback of poor water resistance. In addition, water-based inks using basic dyes have superior advantages over water-based inks using direct dyes and acid dyes, such as richer colors, more vivid colors, and a darker color per unit of weight. On the other hand, it has drawbacks such as poor light resistance and limited solubility, and its range of use is extremely limited. As a result of research aimed at providing an excellent ink composition by eliminating the drawbacks of the water resistance of water-based inks using the above-mentioned water-based dyes and the light resistance and solubility of basic dyes, the present inventors found that We have discovered that an aqueous ink composition consisting of a colored polymer obtained by dyeing a water-soluble polymer containing hydroxyl groups and sulfonic acid groups with a basic dye and a water-soluble organic solvent has excellent water resistance, light resistance, and solubility. The invention has been completed. That is, the present invention provides hydroxyl groups greater than or equal to 1 x 10 ^-3 gram equivalents/gram polymer and 1 x
A mixed solvent solution of water and a water-soluble organic solvent of a colored polymer containing sulfonic acid groups of 10 ^-4 gram equivalent/gram polymer or more and dyed with a basic dye to become water-insoluble. The gist is an aqueous ink composition comprising: In the present invention, a water-insoluble colored polymer is obtained by dyeing a water-soluble polymer containing a hydroxyl group and a sulfonic acid group with a basic dye using a commonly used dyeing method. This can basically be achieved by adding a water-soluble organic solvent before or after dyeing to dissolve the colored polymer in water. It is not theoretically clear why the colored polymer of the present invention is insoluble in water, but the sulfonic acid groups in the water-soluble polymer and the basic dye are ionicly bonded to become hydrophobic, and most of the sulfonic acid groups are It is thought that when ionically bonded with a basic dye, it becomes a water-insoluble colored polymer. On the other hand, the obtained colored polymer has a hydroxyl group and an ionic bonding group in the polymer, so it has excellent affinity with water, and even if it is water-insoluble, it can be used in a relatively small amount of water-soluble organic solvent. It is assumed that it can be dissolved in water. However, a water-insoluble polymer dyed with a basic dye cannot be dissolved in water using a small amount of a water-soluble organic solvent. Based on these facts, the aqueous ink composition of the present invention has excellent water resistance because it uses a water-insoluble colored polymer as a base material, and also has excellent light resistance because the basic dye is ionically bonded to the sulfonic acid group in the polymer. It is considered to have excellent properties and solubility. Furthermore, by increasing the content of sulfonic acid groups in the polymer, it is possible to dye with a basic dye in an amount that could not be obtained conventionally, and a deep-colored aqueous ink can be obtained. For the water-soluble polymer containing hydroxyl groups and sulfonic acid groups used in the present invention, a method of introducing hydroxyl groups and sulfonic acid groups into a pre-produced polymer is also adopted, but in general, a method that is easy to operate is adopted. , a method is employed in which a radically polymerizable vinyl monomer containing a hydroxyl group and a radically polymerizable vinyl monomer containing a sulfonic acid group are polymerized, and/or these monomers and other radically polymerizable vinyl monomers are polymerized. . Examples of the radically polymerizable vinyl monomer containing a hydroxyl group include hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, polyethylene glycol monomethacrylate, methylol acrylamide, and methylol methacrylamide. Examples of radically polymerizable vinyl monomers containing sulfonic acid groups include vinyl sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, acrylamide methylpropanesulfonic acid,
Examples include unsaturated sulfonic acids such as styrene sulfonic acid, vinylbenzyl sulfonic acid, acroyloxyethyl sulfonic acid, methacroyloxyethyl sulfonic acid, and salts thereof, such as lithium salts, sodium salts, potassium salts, ammonium salts, etc. can. Furthermore, other vinyl monomers that can be radically polymerized with the above-mentioned hydroxyl group- and sulfonic acid group-containing monomers include hydrophilic vinyl monomers such as acrylamide, methacrylamide, aminoethyl acrylate, aminoethyl methacrylate, methyl acrylate, ethyl acrylate, Examples include hydrophobic vinyl monomers such as propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, vinyl acetate, acrylonitrile, methacrylonitrile, and styrene; The composition must be such that the polymer obtained is water soluble. Next, these monomers are polymerized to obtain a water-soluble polymer. For example, in a solvent such as water, at a polymerization temperature of 100°C or less, each monomer is combined in bulk or in portions with a normal radical polymerization initiator. This can be easily carried out by introducing the polymer into the polymerization vessel either selectively or continuously. Examples of the radical polymerization initiator used include persulfates such as potassium persulfate and ammonium persulfate;
Alternatively, organic peroxides such as kyumene hydroperoxide and t-butyl hydroperoxide can be used. Further, redox initiators used in combination with reducing agents such as acidic sulfites and ferrous sulfates can also be used. The molecular weight of the resulting water-soluble polymer depends on the concentration of each monomer present in the polymerization system, the amount of radical polymerization initiator used, the polymerization temperature, and the like. The monomer concentration can be selected arbitrarily, but it can generally be carried out at 5 to 50%. Polymerization at a high concentration is not preferred because the viscosity of the polymerization system increases and it becomes difficult to remove the heat of polymerization. Furthermore, polymerization at low concentrations is not preferred for economic reasons. When the amount of the radical polymerization initiator used is increased, the molecular weight of the water-soluble polymer tends to decrease, and when it is decreased, the molecular weight of the water-soluble polymer tends to increase. The molecular weight of the thus obtained water-soluble polymer containing hydroxyl groups and sulfonic acid groups is an important factor as it affects the viscosity of the aqueous ink, and the average molecular weight is 5×10 ⁵ or less, preferably 1×
It should be 10 ⁵ or less. In the present invention, the amount of hydroxyl groups and sulfonic acid groups contained in the water-soluble polymer obtained by the above polymerization method etc. is determined based on the water resistance, light resistance, solubility, viscosity stability, etc. of the ink. The hydroxyl group is at least 1×10 ^-3 gram equivalent/
gram polymer or more, preferably 3×10 ⁻³ gram equivalent/gram polymer or more, and the content of sulfonic acid groups is 1×10 ⁻⁴ gram equivalent/gram polymer or more, substantially 2×10 ⁻⁴ gram equivalent/gram polymer. If it is contained in an amount of gram polymer or more and 3×10 ^-3 gram equivalent/gram polymer or less, satisfactory physical properties can be obtained as a base material for the aqueous ink composition of the present invention. If the content of hydroxyl groups is low, the amount of water-soluble organic solvent used will be large, causing problems such as ink bleeding and set-off, which is not preferable. On the other hand, if the content of sulfonic acid groups is low, not only the ink concentration will be low but also the viscosity stability of the ink will be poor. On the other hand, if the amount is too large, the light resistance of the ink deteriorates, which is not preferable. For the purpose of the present invention, the method of obtaining such a water-soluble polymer is not limited. Next, as basic dyes for dyeing the obtained water-soluble polymer containing hydroxyl groups and sulfonic acid groups, conventional triphenylmethane-based, azo-based, methine-based, oxazine-based, and anthraquinone-based dyes are known. The basic dyes and cationic dyes classified in the Dye Handbook (edited by the Organic Synthetic Chemistry Association, published by Maruzen Co., Ltd.) are used. That is, the "basic dye" in this specification
In a broad sense, it also means cationic dyes. For example, for yellow colors, CI (abbreviation for Color Index) Basic Yellow 11 CI Basic Yellow 13 CI Basic Yellow 14 〃 19 〃 21 〃 25 〃 28 〃 32 〃 36 〃 67 〃 73 etc. For example, examples of orange colors include CI Basic Orange 15 CI Basic Orange 21 〃 22 〃 32 〃 33 〃 34. For example, for red colors, CI Basic Cred 9 CI Basic Cred 13 〃 14 〃 15 〃 18 〃 23 〃 24 〃 27 〃 29 〃 36 〃 38 〃 46 CI Basic Violet 1 CI Basic Violet 3 〃 10 〃 14 〃 15 〃 21 〃 25 〃 27 〃 28 etc. For example, in blue colors, CI Basic Blue 1 CI Basic Blue 3 5 7 9 21 22 25 26 41 44 45 47 64 65 129, etc. For example, in the border color system, CI Basic Green 1 CI Basic Green 4 〃 6 etc. For example, for black, CI Basic Black 2 CI Basic Black 8 etc. are available. Such basic dyes are dyed through ionic bonds with sulfonic acid groups of water-soluble polymers to give colored polymers. The dyeing method is to dye a water-soluble polymer containing hydroxyl groups and sulfonic acid groups with an organic acid such as formic acid, acetic acid, butyric acid, tartaric acid, or malic acid, or with an inorganic acid such as hydrochloric acid or sulfuric acid. Alternatively, it can be carried out by adjusting the pH to a range of 2 to 7 using an aqueous solution of sodium hydroxide, sodium carbonate, etc., and then adding a dye solution. In addition, at this time, for example, the following general formula [] or []
The aqueous ink composition of the present invention can be obtained by adding the water-soluble organic solvent represented by the formula before or after dyeing. General formula []

[Formula] (R ₁ represents H or CH ₃ ; R ₂ and R ₃ both represent H, CH ₃ or C ₂ H _5. ) General formula []

[Formula] (R ₄ represents H or CH ₃ ; X represents NH, NCH ₃ or O; Y represents CH ₂ or O.) Examples of the water-soluble organic solvent represented by the general formula [] include formamide, N-methylformamide, N,N'-dimethylformamide, N,
N'-diethylformamide, acetamide, N
- Examples include methylacetamide. Examples of the water-soluble organic solvent represented by the general formula [] include ethylene carbonate, propylene carbonate, γ-butyrolactone, γ-methylbutyrolactone, 2-pyrrolidone, N-methyl-
Examples include 2-pyrrolidone and 1,3-dimethylimidazolidinone. The amount of water-soluble organic solvent used is usually 5 to 50 wt%, preferably 10 to 40 wt%.
If the amount of water-soluble organic solvent used is large, problems such as ink bleeding and set-off may occur, which is not preferable. For the purposes of the present invention, such dyeing methods are not limited. The aqueous ink composition of the present invention can be used as an aqueous ink by itself, but if necessary, adjuvants commonly used in aqueous inks may be added, such as ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, etc.
Wetting agents such as glycerin and triethanolamine, phenols, paraoxybenzoic acid alkyl esters, sodium omazine, antifungal agents or rust inhibitors such as dioxin, surfactants, and the like can also be added. The aqueous ink composition of the present invention thus obtained has the following characteristics. First, it has excellent water resistance because it is based on a water-insoluble colored polymer. Therefore, the drawbacks of conventional water-based inks, such as ink smearing due to water, sweat, etc., and printed areas disappearing, are eliminated. Second, the disadvantages of salt dyes, which were thought to have low light resistance and solubility, have been overcome by dyeing water-soluble polymers with basic dyes. In other words, it is possible to provide a water-based ink that has the characteristics of a basic dye, such as the richness of colors, the vividness of the color, or the appearance of a deep color per weight unit, and has excellent light resistance and solubility. be. EXAMPLES The present invention will be described in more detail below with reference to Examples, but the present invention is not limited by these Examples. Note that parts and percentages in the examples are based on weight. Water-soluble polymer synthesis example 1 Add 40 parts of water to a nitrogen-substituted polymerization flask and add 90 parts of water.
The temperature was raised to ℃. Spinomer NaSS (sodium P-styrene sulfonate purity 81.0% manufactured by Toyo Soda Kogyo) 56 parts, 2-hydroxyethyl methacrylate
A monomer aqueous solution was prepared by dissolving 116 parts in 488 parts of water. A polymerization initiator aqueous solution was prepared by dissolving 3 parts of ammonium persulfate in 97 parts of water. A monomer aqueous solution and a polymerization initiator aqueous solution were added over 3 hours and polymerized at 90°C. The mixture was further polymerized at 90° C. for 2 hours and cooled. The solution viscosity at 25°C was 32 cps. When the amount of unreacted monomer was determined by the bromine addition method, the polymerization rate of the monomer was 99.1%. In addition, when the average molecular weight of the polymer was determined using the gel permits chromatography method, w3
It was ×10 ⁴ . The polymer was purified, and the sulfur analysis revealed that the polymer contained 1.70×10 ^-3 gram equivalent/gram polymer of sulfonic acid groups, which was the same as the calculated value from the amount of monomer charged. Similarly, the content of hydroxyl groups is 5.6 x 10 ^-3 gram equivalents/gram polymer. Water-soluble polymer synthesis example 2 Pour 50 parts of water into a nitrogen-substituted polymerization flask and add 90 parts of water.
The temperature was raised to ℃. Spinomer NaSS (sodium P-styrene sulfonate purity 81.9% manufactured by Toyo Soda Kogyo) 73 parts, 2-hydroxyethyl methacrylate
A monomer aqueous solution was prepared by dissolving 122 parts of 2-hydroxyethyl acrylate in 603 parts of water. A polymerization initiator aqueous solution was prepared by dissolving 24 parts of ammonium persulfate in 56 parts of water. A monomer aqueous solution and a polymerization initiator aqueous solution were added over 3 hours and polymerized at 90°C. The mixture was further polymerized at 90°C for 2 hours and cooled. The solution viscosity at 25°C was 255 cps. In the same manner as Synthesis Example-1, the polymerization rate of the monomer is
99.5%, and the average molecular weight was w1×10 ⁴ . In addition, the sulfonic acid group in the polymer is 9×10 ^-4 gram equivalent/gram polymer, and the hydroxyl group is 6.6×
It was 10 ^-3 gram equivalent/gram polymer. Water-soluble polymer synthesis example 3 Pour 50 parts of water into a nitrogen-substituted polymerization flask and add 90 parts of water.
The temperature was raised to ℃. A monomer aqueous solution was prepared by dissolving 117 parts of spinomer NaSS (sodium P-styrene sulfonate, purity 81.9%, manufactured by Toyo Soda Kogyo Co., Ltd.), 106 parts of 2-hydroxyethyl methacrylate, and 40 parts of acrylamide in 657 parts of water. A polymerization initiator aqueous solution was prepared by dissolving 19 parts of ammonium persulfate in 61 parts of water. A monomer aqueous solution and a polymerization initiator aqueous solution were added over 3 hours and polymerized at 90°C. The mixture was further polymerized at 90° C. for 2 hours and cooled. The solution viscosity at 25°C was 65 cps. In the same manner as Synthesis Example-1, the polymerization rate of the monomer is
99.3%, and the average molecular weight was w=1×10 ⁴ . In addition, the sulfonic acid group in the polymer is 1.9×
10 ⁻³ gram equivalents/gram polymer, the hydroxyl groups were 3.4×10 ⁻³ gram equivalents/gram polymer. Examples 1 to 3 25 parts of the water-soluble polymer obtained in Water-soluble polymer synthesis example-1, 3 parts of basic dye (manufactured by Hodogaya Chemical),
1 part of acetic acid was dissolved in 51 parts of water and added, and 1 part of acetic acid was dissolved at 60°C.
A colored polymer was prepared by stirring for a period of time, and 20 parts of γ-butyrolactone was added to prepare a water-based ink.

[Table] JIS P3201 writing paper A using felt-tip pens filled with each water-based ink obtained in Examples 1 to 3.
After 1 minute, the writing paper was immersed in water for 1 hour and the state of the handwriting was observed.The handwriting was hardly smudged or smeared, and the density did not change. Furthermore, each water-based ink was applied to the above writing paper using a 1 mil doctor blade and measured using a xenon fade meter (black panel temperature 65°C ± 3°C relative humidity 35 ± 5°C).
%), the sunlight fastness was tested and JIS L-
When compared with the degree of discoloration on the 0841 blue scale, the sunlight fastness of each dye itself was about 1st grade on the blue scale, but all of the above water-based inks were 3rd to 4th grade on the blue scale. Examples 4 to 6 10 parts of the water-soluble polymer obtained in Water-soluble Polymer Synthesis Example-2, 2 parts of basic dye (manufactured by Nippon Kayaku), 1 part of acetic acid, 20 parts of N-methyl-2-pyrrolidone, and 67 parts of water.
10 parts of ethylene glycol and P-
A water-based ink was prepared by adding 0.5 part of methyl hydroxybenzoate.

[Table] Each of the water-based inks obtained in Examples 4 to 6 was subjected to a water resistance test in the same manner as in Examples 1 to 3, but the handwriting did not smear or stain, and the density did not change. Further, the sunlight fastness of each aqueous ink was about grade 4. Examples 7 to 9 20 parts of the water-soluble polymer obtained in Water-soluble polymer synthesis example-3, 6 parts of basic dye (manufactured by Hodogaya Chemical),
1 part acetic acid, 20 parts N,N'-dimethylformamide,
53 parts of water was added and stirred at 60°C for 1 hour to produce a colored polymer, and 15 parts of diethylene glycol was added to prepare a water-based ink.

[Table] The water-based inks obtained in Examples 7 to 9 were subjected to water resistance tests in the same manner as in Examples 1 to 3.
The handwriting did not smear, there was hardly any dirt, and the density remained the same. In addition, the sunlight fastness of each water-based ink is 4.
It was about average. Examples 10-12 10 parts of a basic dye (manufactured by Hodogaya Chemical Co., Ltd.) was added to 50 parts of the water-soluble polymer obtained in Water-soluble Polymer Synthesis Example-2.
40 parts of water was added and stirred at 60°C for 1 hour to produce a colored polymer, and 30 parts of γ-butyrolactone was added to prepare a water-based ink.

[Table] The water resistance and sunlight fastness of each of the aqueous inks obtained in Examples 10 to 12 were comparable to those of Examples 1 to 3. In addition, while each of the water-based inks mentioned above is a uniform aqueous solution, in the case where no water-soluble polymer is used and other conditions are the same, the water-based ink of each dye itself contains insoluble matter of the basic dye. There was a large amount of it, and it was not possible to form a uniform aqueous solution.

Claims (1)

[Scope of Claims] 1. A water-soluble polymer containing hydroxyl groups of 1×10 ^-3 gram equivalent/gram polymer or more and sulfonic acid groups of 1×10 ^-4 gram equivalent/gram polymer or more is dyed with a basic dye. An aqueous ink composition comprising a solution of a colored polymer that is water-insoluble in a mixed solvent of water and a water-soluble organic solvent. 2. The water-based ink composition according to claim 1, wherein the water-soluble organic solvent is represented by the following general formula [] or []. General formula [] [Formula] (R ₁ represents H or CH ₃ ; R ₂ and R ₃ both represent H, CH ₃ or C ₂ H _5. ) General formula [] [Formula] (R ₄ represents H or CH ₃ ; X represents NH, NCH ₃ or O; Y represents CH ₂ or O.)