JP5294547B2 - Recording liquid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording liquid which gives image having excellent solidity and particularly excellent light resistance and reproduces colors in a wide range while maintaining tint. <P>SOLUTION: The recording liquid comprises particles which contain at least a color material and an ultraviolet ray absorbent or an antioxidant, and are dispersed in a medium. In above particles, the relationship of (&Sigma;m<SB>i</SB>&lambda;<SB>i</SB>)/M&lt;320, where m<SB>i</SB>(g) is the weight of the component i, either the ultraviolet ray absorbent or the antioxidant; &lambda;<SB>i</SB>(nm) is the maximum absorption wavelength of the component i; and M(g) is the weight of the color material. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a recording liquid that is particularly suitably used as an ink for an ink jet image forming apparatus.

Conventionally, techniques for improving the fastness of an image by a recording liquid, that is, water resistance, light resistance, gas resistance and the like have been studied and improved. As such a technique, a number of methods for improving the light resistance by changing the structure of the coloring material itself and a method for preventing fading by adding an antioxidant or an ultraviolet absorber have been reported (Patent Document 1, etc.). . For example, Patent Document 1 proposes a method of arranging an additive in the vicinity of the color material by adding an additive such as an ultraviolet absorber or an antioxidant together with the color material when microencapsulating the color material. Yes. According to this technique, the additive can be used efficiently, and an improvement in the fastness of the image is confirmed.
Japanese Patent No. 2562634 (registered on September 19, 1996)

  However, in the technique described in Patent Document 1, the inventors use the additive to lower the color developability of the recording liquid, resulting in a new problem that a desired image quality cannot be obtained. I found. This is considered to be because the additive has absorption in the visible light region, and in particular, the whole image tends to be yellowish. As a result, the color reproduction range becomes narrow, and even if the image is just formed, sufficient image quality may not be obtained.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a recording liquid capable of realizing sufficient fastness of an image without impairing the original color developability of a color material.

The recording liquid of the present invention is a recording liquid in which particles containing at least a coloring material and an ultraviolet absorber or an antioxidant are dispersed in a medium. The particles are provided with a film on the surface thereof. The material and the ultraviolet absorber or antioxidant are contained only in the particles, and the coloring material is C.I. I. In the case of Solvent Red 24, the ultraviolet absorber is Tinuvin (registered trademark) 326, or Tinuvin (registered trademark) 1577, and the ultraviolet absorber is Tinuvin (registered trademark) 326, component i which is an ultraviolet absorber. The weight m _i (g) of the component, the maximum absorption wavelength λ _i (nm) of the component i, and the weight M (g) of the coloring material are represented by the following formula (I):
274.6 ≦ (Σm _i λ _i ) / M ≦ 318.5 (I)
Meet the,
When the ultraviolet absorber is Tinuvin (registered trademark) 1577, the weight _mi (g) of the component i that is the ultraviolet absorber, the maximum absorption wavelength λ _i (nm) of the component i , and the weight M (g of the color material) ) Is represented by the following formula (II)
274.6 ≦ (Σm _i λ _i ) /M≦315.1 (II)
To meet.

  The mode value of the particle diameter of the recording liquid may be 5 μm or less.

Recording liquid of the present invention, by the particles satisfying the formula (I) or (II), the passage of time, during which the light, while preventing thus the discoloration of the image caused by gas or the like to the ultraviolet absorber, colorant the original chromogenic therefore less likely to compromise on these ultraviolet absorbers. That is, the recording liquid satisfying the above formula (I) or (II) has a wide color reproduction range, can improve the image quality immediately after the image formation, and reduce the deterioration of the image quality over a long time. can do.

Recording liquid of the present invention contains at least coloring material and an ultraviolet absorber.

  As the color material, any color material that has been used in conventional recording liquids can be used. Is preferred. Specific examples of the pigment or oil-soluble dye include inorganic pigments such as carbon black, insoluble organic pigments such as furacyanine pigments, azo pigments, and lake pigments. Specific examples include carbon black, furothocyanin blue, furothocyanin green, Hansa yellow, permanent red, solvent red, solvent blue, solvent black, and the like. It is also possible to use a water-insoluble dye by exchanging counter ions (sodium, potassium, ammonium ions) of a water-soluble dye with an organic amine or the like. The proportion of the color material in the entire recording liquid is not particularly limited, but is preferably about 0.1% by weight to 20% by weight.

  Any conventionally known substance can be used as the ultraviolet absorber. As the ultraviolet absorber, specifically, an ultraviolet absorber such as benzotriazole, triazine, or benzophenone can be used. More specifically, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2, 2′-dihydroxy-4,4′-dimethoxy-5-sulfobenzophenone Na salt, 2,2′-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2 ( 2'-hydroxy-5-methylphenyl) benzotriazole and the like are used.

When the ultraviolet absorber is Tinuvin (registered trademark) 1577, the weight _mi (g) of the component i that is the ultraviolet absorber , the maximum absorption wavelength λ _i (nm) of the component i, and the weight M (g of the color material) ) Is represented by the following formula (I)
274.6 ≦ ( Σm _i λ _i ) /M≦318.5 (I)
Meet the,
When the ultraviolet absorber is Tinuvin (registered trademark) 1577, the weight _mi (g) of the component i that is the ultraviolet absorber, the maximum absorption wavelength λ _i (nm) of the component i , and the weight M (g of the color material) ) Is represented by the following formula (II)
274.6 ≦ (Σm _i λ _i ) /M≦315.1 (II)
It can be set arbitrarily within a range that meet the.

“Σm _i λ _i ” in the above formula is the sum of products of the weight of the component i, which is an ultraviolet absorber , and the maximum absorption wavelength of the component i. If, as the particles comprise ultraviolet absorber a, the b, UV absorber incorporated a, the weight of b, _{respectively,} m a, _{m b,} the maximum absorption wavelength lambda _a, and lambda _b Then, these values The weights m _a , m _b , and the color material may be adjusted so that the above satisfies the above formula (I) or (II) .

When the weight m _i (g) of the component i, the maximum absorption wavelength λ _i (nm) of the component i, and the weight M (g) of the coloring material satisfy the above formula (I) or (II) , the ultraviolet absorber is obtained. Therefore, it is possible to suppress the influence of these additives on the color developability of the color material while protecting the image.

Further, when an additive such as an ultraviolet absorber undergoes a structural change such as decomposition in the process of exhibiting its function, the color of these additive itself changes, thereby changing the color of the image. On the other hand, when the recording liquid satisfies the formula (I) or (II) , the image quality can be maintained over a long period of time without causing such a change in hue. Can play.

And the colorant, and ultraviolet absorber, constitutes the particles in the recording liquid. In the particles, the coloring material and the ultraviolet absorber may be mixed, or the ultraviolet absorber may be arranged so as to cover the coloring material. In particular, the particles are preferably microencapsulated.

  In the recording liquid, the particle diameter of the particles including the colorant is preferably 5 μm or less, preferably 1 μm or less, in terms of storage stability of the recording liquid and nozzle clogging. Is more preferable.

The proportion of particles in the entire recording liquid is not particularly limited, but is preferably about 5% to 90% by weight .

  The recording liquid contains a medium in which the particles are dispersed. As the medium, any liquid medium used in conventional recording liquids can be used, and a water-soluble solvent is particularly preferable. Examples of the water-soluble solvent include water, a water-soluble organic solvent, or a mixture of water and a water-soluble organic solvent. Specific examples of the water-soluble organic solvent include alkyl having 1 to 4 carbon atoms such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol. Alcohols; Amides such as dimethylformamide and dimethylacetamide; Ketones or ketoalcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Ethylene glycol and propylene Such as glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, etc. Alkylene glycols in which the ren group contains 2 to 6 carbon atoms; glycerin; polyhydric alcohols such as ethylene glycol methyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether Lower alkyl ethers; N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferred.

  The ratio of the water-soluble organic solvent in the entire recording liquid is not particularly limited as long as the characteristics (fast drying, color development, etc.) as the recording liquid can be realized. Specifically, it is 0 to 95% by weight, preferably 10 to 80% by weight, and more preferably 20 to 50% by weight.

If the particles are those that are microencapsulated, as a method for microencapsulation of water-insoluble solvent and colorant and an ultraviolet absorber dissolved or dispersed to prepare a mixed solution, a water-soluble the mixture An interfacial polymerization method that forms a microcapsule by polymerizing a film-forming material, which is dispersed in a solvent and then separately added to both the water-insoluble solvent and the water-soluble solvent, at the interface of these solvents, a water-insoluble solvent In addition, the so-called In-Situ polymerization method that forms a microcapsule by adding a material that forms a film only, the polymer phase is separated by changing the pH, temperature, concentration, etc. of the aqueous solution of the polymer. Examples include a coacervation method to be formed.

  Water-insoluble solvents used for microencapsulation include vegetable oils (for example, olive oil, soybean oil, castor oil, etc.), mineral oils (for example, petroleum, kesilon, paraffin, etc.), hydrocarbons (for example, alkyl-substituted benzene, alkyl Substituted naphthalene, alkyl-substituted biphenyl, etc.), esters (eg, phthalate ester, benzoate ester, fatty acid ester, citrate ester, phosphate ester, etc.), ethers (eg, glycol ethers), higher alcohols, higher alcohols Water-insoluble solvents such as fatty acids, amides, chlorinated paraffins and silicone oils are preferred.

  When the water-insoluble solvent is dispersed in the water-soluble solvent, ultrasonic waves, various dispersers, and a stirrer can be used. At this time, if necessary, various emulsifiers and dispersants, and further emulsification or dispersion aids such as protective colloids can be used. For example, polymer substances such as PVA, PVP and gum arabic, anionic surfactants, nonionic surfactants and the like can be mentioned.

  Examples of film forming materials include terephthaloyl chloride, toluene diisocyanate, bisphenol A, ethylene diamine, ethylene glycol, styrene, divinylbenzene, gelatin, gum arabic, carboxymethyl cellulose, and the like.

  In the formation of microcapsules, a pH adjuster may be used. Examples of the pH adjuster include various organic amines such as diethanolamine and triethanolamine, sodium hydroxide, lithium hydroxide, potassium hydroxide, and the like. Examples thereof include inorganic alkali agents such as alkali metal hydroxides, organic acids such as acetic acid, and mineral acids.

  The recording liquid may be a medium in which the water-soluble solvent used for the formation of the particles is dispersed, and the particles may be dispersed as is in this medium. The particles may be dispersed in a medium.

  The recording liquid is suitably used as ink for an ink jet printing apparatus. The recording material to be used can be any of general paper, coated paper, synthetic paper, various plastic films and the like, and is not particularly limited.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. However, the following is only an example, and the present invention has the effects described above in the technical scope described in the claims. is there. In the following description, “%” means “% by weight” unless otherwise specified.

[Reference Example 1]
10 g of tri-n-butyl phosphate, C.I. I. 2 g of Solvent Red 24 (manufactured by Orient Chemical Co., Orient Oil Red RR) and 1.5 g of ultraviolet absorber Tinuvin 326 (trade name, manufactured by Ciba Specialty Chemicals Inc., maximum absorption wavelength 353 nm) were mixed. This was added to 30 g of a 10% gelatin aqueous solution, and emulsified and dispersed by mixing for 15 minutes at 12,000 rpm using a homomixer manufactured by Tokushu Kika Kogyo, and then added and mixed with 30 g of a 10% aqueous gum arabic solution. Further, 40 g of water at 40 ° C. was added, and the pH was adjusted to 4.0 to 4.4 with 10% acetic acid. This was cooled to 5 ° C., 1 g of 30% formalin was added, and the pH was adjusted to 9 with 10% NaOH. The temperature was gradually raised to 50 ° C. to form microcapsules.

To 15 g of microcapsules taken out from the reaction solution, 5 g of polyethylene glycol, 5 g of N-methyl-2-pyrrolidone and 75 g of distilled water were added and stirred for 2 hours to obtain the ink of Reference Example 1 .

[Reference Example 1]
According to the formulation of the microcapsules of this reference example, (Σm _i λ _i ) / M is {353 (nm, maximum absorption wavelength of Tinuvin 326) × 1.5 (g, addition amount of Tinuvin 326) } / 2 (g, C.I. smaller than the addition amount) = 264.75 and become by 320 of solvent Red 24.

[ Examples 1-3 ]
In Reference Example 1 , inks shown in Table 1 were obtained by adjusting the amount of the ultraviolet absorber.

[ Example 4 ]
Reference Example 1, an ultraviolet absorber Tinuvin326 the Tinuvin1577 (trade name, manufactured by Ciba Specialty Chemicals Ltd., maximum absorption wavelength 274 nm) was changed to 2.3g was obtained an ink of Example 4 in the same manner as in Reference Example 1 .

According to the formulation of the microcapsules of this example, (Σm _i λ _i ) / M is {274 (nm, maximum absorption wavelength of Tinuvin 1577) × 2.3 (g, addition amount of Tinuvin 1577) / 2 (g, C .I. becomes amount) = 315.1 solvent Red 24, satisfies the above inequality (II).

[ Examples 5-7 ]
In Example 4 , the amount of the ultraviolet absorber was adjusted to obtain inks shown in Table 1.

[Comparative Example 1]
Reference Example 1, except that the amount of the ultraviolet absorber Tinuvin326 was 2g was obtained an ink of Comparative Example 1 in the same manner as in Reference Example 1.

According to the composition of this comparative example, (Σm _i λ _i ) / M is {353 (nm, maximum absorption wavelength of Tinuvin 326) × 2 (g, addition amount of Tinuvin 326)} / 2 (g, CI solvent. (Addition amount of red 24) = 353, which is larger than 320, and does not satisfy the inequalities (I) and (II) .

[Comparative Example 2]
In Comparative Example 1, the amount of the ultraviolet absorber was adjusted to obtain inks shown in Table 1.

[Comparative Examples 3 to 4]
In Example 4 , the amount of the ultraviolet absorber was adjusted to obtain inks shown in Table 1.

[Comparative Example 5]
In Reference Example 1 , an ink of Comparative Example 5 was obtained in the same manner as Reference Example 1 except that the ultraviolet absorber Tinuvin 326 was not added.

〔Evaluation method〕
Copy paper using an ink jet recording apparatus having an on-demand type recording head (ejection orifice system 50 μm, piezo vibrator driving voltage 18 V, frequency 10 KHz) that ejects ink by a piezo vibrator using the inks of the above and comparative examples, respectively. An image was formed by printing. A xenon fade meter (manufactured by Gas Tester) was used for the image thus obtained, and light was irradiated for 100 hours. The color difference ΔE ₁ before and after light irradiation of the same image was obtained with RD-19I manufactured by Gretag Macbeth. A smaller value ΔE ₁ means that the color change due to light is small, that is, the light resistance is excellent. Further, the color change due to the addition of the additive is determined by the color difference ΔE ₂ obtained by calculating the difference between the chromaticity of the image before irradiation in each of the examples and the comparative examples and the chromaticity of the image before irradiation in the comparative example 5 . Evaluated. The evaluation results are shown in Table 1.

〔result〕
1 and 2 are graphs of the results shown in Table 1. FIG. 1 shows the results of Reference Example 1 (a), Examples 1 to 3 ( b to d), and Comparative Examples 1 (e) and 2 (f), and FIG. 2 shows Examples 4 to 7 (g to j) represents the results of Comparative Examples 3 (k) and 4 (l). The vertical axis is the color difference, and the horizontal axis is (Σm _i λ _i ) / M.

As shown in FIG. 1, Reference Example 1 (a) and Examples 1 to 3 ( b to d) have a color difference ΔE ₂ with Comparative Example 1 (e) and Comparative Example 5 that does not use an ultraviolet absorber. It was smaller than 2 (f). Further, as apparent from the color difference ΔE ₁ before and after the irradiation, the same light resistance as in Comparative Examples 1 (e) and 2 (f) was exhibited. That is, it was possible to realize good light resistance without deteriorating the color developability of the ink by the color material.

In addition, as shown in FIG. 2, Examples 4 to 7 (g to j) have a color difference ΔE _{2 from} Comparative Example 5 that is smaller than Comparative Examples 3 (k) and 4 (l), and sufficient light resistance. Showed sex. That is, it was possible to realize good light resistance without deteriorating the color developability of the ink by the color material.

Reference Example 1 (a) of the present invention, Examples 1 to 3 ( b to d), and Comparative Examples 1 (e) and 2 (f) before and after light irradiation ΔE ₁ (♦) and Comparative Example 5 color difference ΔE ₂ (■) is a graph showing a. Color difference ΔE ₁ (♦) before and after light irradiation and Comparative Example 5 color difference ΔE ₂ (■) in Examples 4 to 7 (g to j) and Comparative Examples 3 (k) and 4 (l) of the present invention are shown. It is a graph.

Claims (3)

A recording liquid in which particles containing at least a coloring material and an ultraviolet absorber are dispersed in a medium,
The particles comprise a film on the surface,
In the recording liquid, the colorant and the ultraviolet absorber are contained only in the particles,
The color material is C.I. I. Solvent Red 24,
The ultraviolet absorber is Tinuvin (registered trademark) 326, or Tinuvin (registered trademark) 1577,
When the ultraviolet absorber is Tinuvin (registered trademark) 326, the weight _mi (g) of the component i that is the ultraviolet absorber, the maximum absorption wavelength λ _i (nm) of the component i, and the weight M ( g) is represented by the following formula (I)
274.6 ≦ (Σm _i λ _i ) /M≦318.5 (I)
The filling,
When the ultraviolet absorber is Tinuvin (registered trademark) 1577, the weight _mi (g) of the component i which is the ultraviolet absorber, the maximum absorption wavelength λ _i (nm) of the component i, and the weight M ( g) is represented by the following formula (II)
274.6 ≦ (Σm _i λ _i ) /M≦315.1 (II)
Recording liquid that satisfies It is 5μm or less mode of the particle diameter before Symbol particles, recording liquid according to claim 1. A recording liquid obtained by mixing at least a medium and particles containing at least a coloring material and an ultraviolet absorber,
The particles comprise a film on the surface,
When performing the mixing, the colorant and the ultraviolet absorber are included only in the particles,
The color material is C.I. I. Solvent Red 24,
The ultraviolet absorber is Tinuvin (registered trademark) 326, or Tinuvin (registered trademark) 1577,
When the ultraviolet absorber is Tinuvin (registered trademark) 326, the weight _mi (g) of the component i that is the ultraviolet absorber, the maximum absorption wavelength λ _i (nm) of the component i, and the weight M ( g) is represented by the following formula (I)
274.6 ≦ (Σm _i λ _i ) /M≦318.5 (I)
The filling,
When the ultraviolet absorber is Tinuvin (registered trademark) 1577, the weight _mi (g) of the component i which is the ultraviolet absorber, the maximum absorption wavelength λ _i (nm) of the component i, and the weight M ( g) is represented by the following formula (II)
274.6 ≦ (Σm _i λ _i ) /M≦315.1 (II)
Recording liquid that satisfies

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