JPH0527551B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an inkjet recording method, and more particularly to a method for improving multicolor inkjet recording. [Prior Art] The inkjet recording method uses various recording liquid ejection methods (for example, an electrostatic suction method, a method that applies mechanical vibration or displacement to the recording liquid using a piezoelectric element, and a method in which the recording liquid is heated and foamed). (methods that use pressure, etc.)
This method generates small droplets of recording liquid (ink) and makes them fly, and some or all of them adhere to a recording material such as paper to perform recording, but it generates less noise and It is attracting attention as a recording method that allows high-speed printing and multicolor printing. Water-based recording liquids are mainly used for inkjet recording in view of safety and printability, while ordinary paper has conventionally been used as the recording material. When recording using liquid ink, it is generally necessary that the recording liquid does not bleed onto the recording paper and cause the print to become blurry, and that the recording liquid dries as quickly as possible after recording, resulting in unexpected damage. It is desirable not to contaminate the paper surface. In particular, in a multicolor inkjet recording system that uses recording liquids of two or more different colors, 1. The absorption of the recording liquid into the recording material is rapid, and even if different color ink dots overlap,
The recording liquid deposited later should not mix with the recording liquid deposited earlier, disturb the ink dots, or flow out. 2. The recording liquid droplets should not spread on the recording material and the diameter of the ink dots should not be larger than necessary. 3. The shape of the ink dot should be close to a perfect circle, and the periphery should be smooth. 4. The density of the ink dot should be high and the periphery of the dot should not be blurred. 5. The recording material should be white and have a good contrast with the ink dot. 6. The color of the recording liquid does not change depending on the recording material; 7. Dimensional variation of the recording material (e.g. wrinkles, stretching)
It is necessary to satisfy various requirements such as that the amount of data is small before and after recording. However, in the past, it has been understood that satisfying these requirements depends greatly on the characteristics of the recording material and recording liquid used, but in reality, there are no inkjet recording methods that meet the above requirements. It is still not found. For example, if we consider the relationship between the recording material and the recording liquid, we can see that inkjet recording is performed on high-quality office paper using a normal recording liquid (with a water content of about 70%). If this is done, the ink absorption will be poor, the degree of bleeding will be uneven, and the shape of the dots will be extremely poor. When inkjet recording is performed on this paper using a recording liquid with a low water content (50% water or less), the ink absorbency is improved to some extent, but the dot shape and color properties are adversely affected. Furthermore, when inkjet recording is performed on commercially available non-coated paper, the ink absorbency exhibits sufficient characteristics regardless of the water content, but the dot shape and color properties are poor. Furthermore, when inkjet recording is performed on coated paper for printing, the dot shape is good if a recording liquid with a high water content (70% or more water) is used, but the dot density is low and the ink absorption is very poor. bad. Conversely, a recording liquid with a low water content (less than 50% water) has good ink absorption, but the dot density is low. On the other hand, since the inkjet recording method uses water-based ink, there is a problem that the recorded images lack water resistance, and when exposed to water, the ink bleeds and becomes unreadable.There is also a need to solve this problem. It had been. For example, the inkjet recording paper described in JP-A-56-99693 contains quaternary ammonium halide to impart water resistance. However, such water-resistant inkjet recording paper has a drawback in that the light resistance of the recording material (dye, etc.) is significantly reduced. This probably occurs because the photocatalytic action of the halogen promotes photodecomposition of the dye. [Problems to be Solved by the Present Invention] An object of the present invention is to satisfy all the problems that the prior art could not solve in the technical field mentioned above. Particularly, the present invention aims to simultaneously satisfy the above-mentioned requirements in recording color images using a plurality of color recording liquids using an inkjet recording method, particularly excellent water resistance and good light resistance. Another object of the present invention is to provide a new inkjet recording method that can consistently exhibit excellent recording characteristics even when recording liquids with a wide range of water contents are used. The above and other objects are achieved by the following invention. [Structure and operation of the invention] That is, the present invention provides an inkjet recording method in which recording is performed by attaching small droplets of recording liquid to a recording material, in which the recording material is a base material or a coating provided on the base material. Expression in layer () (In the formula, X ^- is a chloride ion, a bromide ion,
containing a polyallylamine salt represented by at least one of iodide ions, nitrate ions, phosphate ions, acetate ions, benzoate ions, and p-toluenesulfonate ions;
and the water content of the recording liquid is less than the total weight of the recording liquid.
This is an inkjet recording method characterized by using an aqueous recording liquid in the range of 20 to 90%. However, in formula (), n is 5 to 10,000, more preferably 10 to 1,000. When n is less than 5, water resistance is insufficient, and when n is greater than 10,000, when made into an aqueous solution, the viscosity is high and workability is poor. The base material of the recording material used in the present invention is typically paper, but cloth, resin film, synthetic paper, etc. can also be used as the base material. Examples of the method for producing the recording material used in the present invention by incorporating a polyallylamine salt represented by the formula () into a base material include, for example, a papermaking method using an aqueous solution of the polyallylamine salt in a papermaking process; There is a post-treatment method in which the polyallylamine salt is added to the impregnating liquid and the substrate is immersed therein, but any method may be used. In these cases, the optimum concentration of the polyallylamine salt aqueous solution varies depending on the viscosity of the aqueous solution and the solubility of the polyallylamine salt, but in general,
It is appropriate to use 0.05 to 2% by weight. Furthermore, if the amount of the polyallylamine salt contained in the base material is too large, ink absorption will decrease, which is not preferable. On the other hand, in the recording material used in the present invention of the type containing the polyallylamine salt of formula () in the coating layer on the base material, the polyallylamine salt is added to the coating liquid, and this coating liquid is applied to the base material. It is manufactured by coating and drying. Other components of the coating liquid in this case include conventionally known fine powder silicic acid, clay,
Talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, titanium oxide, zinc oxide,
Inorganic pigments such as satin white, aluminum silicate, and litovone; Water-soluble polymers such as starch, gelatin, casein, gum arabic, sodium alginate, carboxymethyl cellulose, polyvinyl alcohol, polyvinylpyrrolidone, and sodium polyacrylate; Synthetic rubber latex, etc. Synthetic resin latex: Organic solvent-soluble resins such as polyvinyl butyral and polyvinyl chloride: In addition, various additives such as dispersants, fluorescent dyes, PH adjusters, antifoaming agents, lubricants, preservatives, and surfactants can be mentioned. can. The amount of polyallylamine salt added to the coating solution is suitably in the range of 0.03 to 5% by weight. The coating liquid is usually applied at a rate of about 1 to 50 g/m ² (dry coating amount) by a known method such as a roll coater method, a blade coater method, an air knife coater method, etc.
Coat the amount on the substrate. Preferably 2-30g/
Apply approximately ² m (dry coating amount). On the other hand, the recording liquid used in the method of the present invention consists of a recording agent such as a dye and a liquid medium component. As the liquid medium component of the recording liquid, a mixture of water and various water-soluble organic solvents is used, and the water content in the recording liquid is adjusted to be within the range of 20 to 90% by weight. Ru. If the water content in the recording liquid exceeds 90% by weight, even if the above-mentioned recording material is used, the affinity of the recording liquid to the surface of the recording material will be insufficient, and the absorbency of the recording liquid will decrease. This increases the time it takes for the recording liquid to fix, which limits the recording speed. In addition, when recording liquids overlap, recording liquids of different colors may mix, and ink dots may become unnecessarily enlarged or disordered. It's not appropriate. In addition, such a recording liquid has problems in terms of ejection stability and dissolution stability of the recording agent, and is not suitable. Further, if the water content in the recording liquid is less than 20% by weight, even if the above-mentioned recording material is used, the color property, bleeding, and dot shape will be insufficient, so it is not suitable. Examples of the water-soluble organic solvent include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and isobutyl alcohol, each having 1 to 4 carbon atoms. Amides such as dimethylformamide and dimethylacetamide; Ketones or ketone alcohols such as acetone and diacetone alcohol; Ethers such as tetrahydrofuran and dioxane; Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol , propylene glycol, 1.2.6-hexanetriol, thiodiglycol, hexylene glycol,
2-6 alkylene groups such as diethylene glycol
alkylene glycols containing 5 carbon atoms; glycerin; ethylene glycol methyl ether;
Examples include lower alkyl ethers of polyhydric alcohols such as diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether. 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. Polyhydric alcohols are particularly preferred because they are highly effective as wetting agents to prevent nozzle clogging caused by evaporation of water in the recording liquid and precipitation of the recording agent. A solubilizer can also be added to the recording liquid. Typical solubilizing agents are nitrogen-containing heterocyclic ketones, and their intended action is to dramatically improve the solubility of recording agents in liquid media. For example, N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are preferably used. A recording liquid prepared from such components has its own recording properties (signal response, stability of droplet formation, ejection stability, long-term continuous recording performance, ejection stability after a long period of recording interruption). ), has excellent storage stability and fixability to recording materials, but in order to further improve these properties, various additives may be further included. For example, viscosity modifiers such as polyvinyl alcohol, cellulose, and water-soluble resins; various cationic, anionic, or nonionic surfactants;
Surface tension adjusters such as diethanolamine and triethanolamine: Examples include PH adjusters using buffer solutions. Further, in order to prepare a recording liquid used in an inkjet recording method of the type in which the recording liquid is charged, a resistivity adjusting agent such as inorganic salts such as lithium chloride, ammonium chloride, and sodium chloride is added. Note that when applied to an inkjet method in which the recording liquid is ejected by the action of thermal energy, the thermal properties (e.g., specific heat, coefficient of thermal expansion, thermal conductivity, etc.) may be adjusted. be. [Effects] According to the method of the present invention, the ink is quickly absorbed into the ink, and even when recording liquids of different colors are repeatedly deposited on the same spot within a short period of time, the phenomenon of recording liquid flowing out or seeping out is prevented. You can get high-resolution, clear images. Moreover, the obtained image exhibits excellent properties in both water resistance and light resistance, and is suitable for inkjet recording methods. Hereinafter, the present invention will be explained in more detail according to Examples and Comparative Examples. Example 1 Polyallylamine hydrochloride PAA-HCl-H (manufactured by Nittobo Co., Ltd.) with w (weight average molecular weight determined by ultracentrifugation) 60,000 was used as the polyallylamine salt, and coating was performed based on the following composition. A composition for use was prepared. Fine powder silicic acid 100 parts by weight Polyvinyl alcohol 50 〃 PAA-HC1-H 1 〃 Water 500 parts by weight On the other hand, as a base material, general high-quality paper (basis weight 65 g/m ² ) with a sizing degree of 35 seconds based on JIS P8122 was used. dry coating amount of the above coating composition on this base material.
It was coated at a rate of 15 g/m ² by a blade coater method and dried by a conventional method to obtain a recording material (1). Color inkjet recording was performed on this recording material using the following inks, and the recording characteristics were evaluated. Ink No.A Water content: approx. 90wt% (composition) Glycerin 8 parts by weight Water 90 〃 CI Direct Blue 86 2〃 Ink No.B Water content: approx. 70wt% (composition) Glycerin 28 parts by weight Water 70 〃 CI Direct Blue 86 2 Ink No. C Water content: approx. 50 wt% (composition) Ethylene glycol 48 parts by weight Water 50 CI Direct Blue 86 2 Parts by weight Ink No. D Water content: approx. 30 wt% (composition) Diethylene glycol 20 parts by weight N-methyl -2-pyrrolidone 20 〃 Ethyl cellosolve 28 〃 Water 30 〃 CI Direct Blue 86 2 〃 Ink No. E Water content approximately 20wt% (Composition) Diethylene glycol 10 parts by weight N-methyl-2-pyrrolidone 30 〃 Ethyl cellosolve 38 〃 Water 20 〃 CI Direct Blue 86 2 〃 Ink No.F Water content approximately 10wt% (composition) Diethylene glycol 10 parts by weight N-methyl-2-pyrrolidone 40 〃 Ethyl cellosolve 38 〃 Water 10 〃 CI Direct Blue 86 2 〃 Recording material Table 1 shows the evaluation results of recording characteristics.
The degree of bleeding was determined by measuring the diameter of a printed dot using a stereomicroscope and indicating how many times larger the diameter of the printed dot was than that of an ink droplet. For color development, optical density (OD) was measured using a Macbeth densitometer. Water resistance was evaluated by immersing the recording material in running water for 1 hour and comparing the optical density (OD) measured using a Macbeth densitometer after immersion with the OD value before immersion.
In addition, the light resistance is xenon fade meter 100
The sample was irradiated for a period of time, and the color difference (Hunter ΔE) from that of the non-irradiated sample was determined using a colorimeter ND-1001-DP (manufactured by Nippon Denshoku Kogyo Co., Ltd.). Example 2 As the polyallylamine salt, polyallylamine hydrochloride PAA-HCl-L (manufactured by Nittobo Co., Ltd.) with w (weight average molecular weight determined by ultracentrifugation) 10000 was used, and 1% of polyallylamine hydrochloride was used. Create an aqueous solution and add it to general paper with a size degree of 0 seconds (basis weight 70g/
m ² ), dried, and impregnated with polyallylamine salt in an amount of about 0.5% by weight based on the base material.
I got (2). Table 1 shows the results of evaluating this recording material in the same manner as in Example 1. Example 3 Same as Example 1 except that w5000 polyallylamine phosphate was used as the polyallylamine salt.
Recording material (3) was prepared in the same manner as above. The recording characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 1. Comparative Example 1 A recording material (4) was prepared in the same manner as in Example 1, except that the polyallylamine salt was not added to the coating composition. The recording characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 1. Comparative Example 2 The base material used in Example 2 was used as a recording material (5) without any treatment. The recording characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 1. Comparative Example 3 A recording material (6) was prepared in the same manner as in Example 1, except that lauryltrimethylammonium chloride was used instead of the polyallylamine salt used in Example 1. The recording characteristics were evaluated in the same manner as in Example 1, and the results are shown in Table 1. Comparative Example 4 Table 1 shows the recording characteristics when recording was performed on each of recording materials (1) to (6) using ink No. F (water content 10 wt%). Water resistance and light resistance remained the same, but the degree of bleeding, color, and dot shape were insufficient. As mentioned above, Examples 1 to 3 and Comparative Examples 1 to 4 are summarized in Table 1.

【table】

[Table] Examples 4 to 6 In place of polyallylamine hydrochloride, respectively
A recording material was prepared in the same manner as in Example 1, except that polyallyl acetate of w2000, polyallylamine P-sulfonate of w7000, and polyallylamine benzoate of w100000 were used. The evaluation results of recording characteristics were almost similar to those of Example 1.

Claims (1)

[Scope of Claims] 1. In an inkjet recording method in which recording is performed by attaching droplets of a recording liquid to a recording material, the recording material has a base material or a coating layer provided on the base material having a formula ( ) (In the formula, X ^- is a chloride ion, a bromide ion,
Represents iodide ion, nitrate ion, phosphate ion, acetate ion, benzoate ion, p-toluenesulfonate ion, consisting of at least one type)
1. An inkjet recording method, characterized in that the recording liquid is an aqueous recording liquid containing a polyallylamine salt represented by the following formula, and the water content of the recording liquid is in the range of 20% to 90% of the total weight of the recording liquid.