JPH10272831A - Ink jet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high water resistance by a method wherein a recording medium prepared by providing an ink receiving layer consisting of a neutralized matter obtained by reacting a copolymer, which is prepared by compounding a maleic anhydride unit and two specified structural units at specified compounding ratios, with ammonia. SOLUTION: As a recording medium, one, which is produced by providing a specified ink receiving layer on a support. The specified ink receiving layer is made of a neutralized matter obtained by reacting a copolymer consisting of a maleic anhydride unit, a structural unit represented by a formula I, in which R<1> -R<3> are hydrogen atoms or the like, and a structural unit represented by a formula II, in which R<4> represents hydrogen atom or the like and R<5> represents alkyl group or the like and having the compositional molar ratio of the laleic adhydride : the structural unit represented by the formula I : the structural unit represented by the formula II = 1:0.8-1.2:0-2, with ammonia. Then, by heat treating the recording medium after images are formed thereon at the temperature higher than 80 deg.C, an excellent water resistance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an ink jet recording method.

[0002]

2. Description of the Related Art The ink jet recording method has been applied to facsimile machines and various printers because of its low noise, easy recording of recorded images, and high speed recording. . Conventionally, paper has been used as a recording medium in the ink jet recording method, and a polyester film or the like having poor ink absorption has not been used. However, with the improvement of the performance of the ink jet printing apparatus such as high-speed printing and multi-color printing, more advanced characteristics are required for the printing medium. Specifically, the ink absorption speed is high, the diameter of the ink dot does not become larger than necessary (less bleeding), and the water resistance of the recorded image is improved. Further, it is required to enable recording even on a polyester film which has not been used as a recording medium.

[0003]

As a recording medium in the ink jet recording method, an ink receiving layer made of a water-soluble or hydrophilic resin such as a polyvinyl alcohol resin is provided on a support such as paper or a polyester film. Although a recording medium is known, in a recording medium after forming an image, the recorded image is affected by humidity in the air, water droplets, and the like because the resin forming the ink receiving layer is water-soluble or hydrophilic. It tends to be unclear, and there is a problem in the water resistance of the recorded image. For this reason, it is necessary to pay sufficient attention to storage of the recorded image, and it is difficult to apply it to an outdoor poster or the like. The present invention has been made in view of the problems of the related art, and an object of the present invention is to provide an ink jet recording method capable of forming a recorded image having high water resistance.

[0004]

According to the present invention, an object of the present invention is to provide an ink-jet recording method for performing recording by ejecting ink onto a recording medium to form an image on the recording medium. Unit, equation (1)

[0005]

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(Wherein R ¹ and R ² each represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ³ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms and a cycloalkyl having 3 to 12 carbon atoms. A structural unit represented by the formula (2):

[0007]

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Wherein R ⁴ is a hydrogen atom or a methyl group;
R ⁵ is an alkyl group having 1 to 18 carbon atoms or 3 to 1 carbon atoms.
And a compositional molar ratio thereof is [maleic anhydride unit]: [structural unit represented by formula (1)]: [formula (2) Structural unit represented] = 1: 0.8 to 1.2: 0 to 2 (hereinafter abbreviated as a maleic anhydride copolymer), which is obtained by reacting a copolymer with ammonia. The problem is solved by providing an ink jet recording method comprising using a recording medium having an ink receiving layer made of a material on a support, and heat-treating the recording medium after image formation at a temperature of 80 ° C. or higher. Is done.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The structural unit represented by the formula (1) and the structural unit represented by the formula (2) constituting the maleic anhydride copolymer in the present invention are represented by the following formula (3), respectively. It is derived from a monomer represented and a (meth) acrylate-based monomer represented by the following formula (4).

[0010]

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(Wherein R ¹ , R ² and R ³ are as defined above)

[0012]

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(Wherein R ⁴ and R ⁵ are as defined above)

In the above formulas (3) and (4), R
^1, the alkyl group of R ² and 8 carbon atoms R ³ represents, for example a methyl group, an ethyl group, a propyl group, an isopropyl group, n- butyl group, etc. n- octyl group. Examples of the alkyl group having 1 to 18 carbon atoms represented by R ^5, for example a methyl group, an ethyl group, n- butyl group, and stearyl group. And R ³ and R ⁵
Examples of the cycloalkyl group having 3 to 12 carbon atoms represented by include a cyclopropyl group and a cyclohexyl group.

Here, examples of the monomer represented by the formula (3) include a linear or branched α-olefin and a vinyl monomer having a benzene ring such as styrene. Examples of the monomer represented by the formula (3) include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 2-methyl-1-butene, 1-hexene, and 2-hexene.
Methyl-1-pentene, 3-methyl-1-pentene, 4
Examples thereof include -methyl-1-pentene, 2-ethyl-1-butene, and styrene. Of these, isobutylene is preferable. The monomers represented by the formula (3) may be used alone or in combination of two or more.

The (meth) acrylate monomer represented by the formula (4) includes, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl ( Examples thereof include (meth) acrylate and cyclohexyl (meth) acrylate, and among them, methyl methacrylate and n-butyl acrylate are preferable. The (meth) acrylate monomers represented by the formula (4) may be used alone or in combination of two or more.

The above maleic anhydride copolymer can be prepared by changing the composition molar ratio of the maleic anhydride unit, the structural unit represented by the formula (1) and the structural unit represented by the formula (2). It has characteristics. The composition molar ratio of each structural unit is usually [maleic anhydride unit]: [structural unit represented by formula (1)]: [structural unit represented by formula (2)] = 1: 0.8 to 1.2: 0 to 2, but from the viewpoints of ink absorbency, flexibility, strength and the like when the ink receiving layer is used, [maleic anhydride unit]: [the structural unit represented by the formula (1)] ]: [Structural unit represented by formula (2)] = 1: 0.9 to 1.1: 0 to 1.5 is preferable. From the viewpoint of workability in forming the ink receiving layer, the maleic anhydride copolymer is represented by the formula (2)
It is preferable to contain the structural unit represented by the formula at a ratio of 0.1 mol or more per 1 mol of the maleic anhydride unit.

The number average molecular weight of the above-mentioned maleic anhydride copolymer is usually 1,000 to 500,000, but the strength when used as an ink receiving layer, workability when forming an ink receiving layer, and the like. 5,000 to 10
Preferably it is 000.

The maleic anhydride copolymer according to the present invention comprises a maleic anhydride, a monomer represented by the formula (3) and, if necessary, a (meth) acrylate monomer represented by the formula (4) (Hereinafter, these are abbreviated as raw material monomers) and can be produced according to a conventional method. For example, it can be produced by charging a raw material monomer in a reaction vessel and copolymerizing it in a solvent by a solution polymerization method using a radical polymerization initiator.

As the radical polymerization initiator, those conventionally used can be used without particular limitation.
For example, di (dodecanoyl) peroxide, benzoyl peroxide, cumene hydroperoxide, t
Organic peroxides such as butyl hydroperoxide;
2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), dimethyl-2,
2′-azobisisobutyrate, α, α′-azo-α-
An azo compound such as ethylbutyronitrile can be used. The amount of the radical polymerization initiator used is not particularly limited, but is usually in the range of 0.05 to 5 parts by weight based on 100 parts by weight of the raw material monomer.

Examples of the solvent used in the polymerization include various solvents which do not inhibit radical polymerization, for example, ketones such as acetone and methyl ethyl ketone; aliphatic hydrocarbons such as n-hexane and n-octane; benzene, toluene And aromatic hydrocarbons such as ethylbenzene; fatty acid esters such as ethyl acetate and isopropyl acetate; ethers such as diisopropyl ether, dioxane and tetrahydrofuran; and chlorinated hydrocarbons such as methylene chloride and chloroform. . These solvents may be used alone or as a mixture of two or more.

The molar ratio of the charged amounts of the raw material monomers is the same as the composition molar ratio of the structural units constituting the maleic anhydride copolymer, that is, [maleic anhydride]: [monomer represented by the formula (3)] Monomer]: [(meth) acrylate-based monomer represented by formula (4)] = 1: 0.8 to 1.2: 0.

When the raw material monomers are charged, the maleic anhydride copolymer having a uniform composition can be obtained by charging the raw material monomers in consideration of the difference in reactivity.
For example, when the reactivity of the (meth) acrylate-based monomer represented by the formula (4) is low, it is necessary to charge the (meth) acrylate-based monomer in the initial stage of the polymerization reaction so as to increase the concentration of the (meth) acrylate-based monomer. Is preferred. Further, it is preferable that maleic anhydride is charged in such a ratio that the concentration in the reaction system becomes constant throughout the polymerization reaction.

The polymerization temperature varies depending on the solvent and the radical polymerization initiator used, but is generally in the range of 0 to 200 ° C., preferably 20 to 150 ° C. The polymerization time is
It generally ranges from 1 to 50 hours, preferably from 2 to 20 hours. The polymerization can be carried out under normal pressure, under pressure or the like.

After the completion of the polymerization reaction, the obtained maleic anhydride copolymer can be separated and obtained according to a conventional method. For example, filtration of the precipitated maleic anhydride copolymer,
A method of removing liquid and then drying, a method of removing a solvent from a solution of the maleic anhydride copolymer, and then drying the remaining maleic anhydride copolymer are exemplified.

Since the above maleic anhydride copolymer contains maleic anhydride units, its acid anhydride groups react with ammonia to form salts and become neutralized products. The neutralized product of the maleic anhydride copolymer exhibits water solubility.

Ammonia has a degree of neutralization of usually 0.3 to 1, preferably 0.5 to 1, with respect to the maleic anhydride copolymer.
Use amounts that fall in the range of 0.8. Here, the degree of neutralization indicates the ratio between the acid groups in the maleic anhydride copolymer and ammonia, and the number of moles of the carboxyl groups in the maleic anhydride copolymer is x (mol). When the amount of ammonia thus obtained is y (mole), it is given by y / x. The calculation is made on the assumption that the acid anhydride groups in the maleic anhydride copolymer correspond to two carboxyl groups. In the above description, as the degree of neutralization of the maleic anhydride copolymer increases, the ink absorption rate of the ink receiving layer tends to increase.

The reaction between the maleic anhydride copolymer and ammonia can be carried out according to a conventional method, but it is convenient to carry out the reaction in the presence of water to obtain a neutralized product of the maleic anhydride copolymer as an aqueous solution. At this time, ammonia can be used as aqueous ammonia.

In the present invention, in addition to ammonia, alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, lithium hydroxide and calcium hydroxide may be used insofar as the gist of the invention is not impaired. Hydroxide; alkali metal carbonates such as sodium carbonate and potassium carbonate; alkali metal acetates such as sodium acetate and potassium acetate; and other basic substances such as ammonium acetate may be used in combination.

In the present invention, when forming the ink receiving layer on the recording medium, other resins can be used in combination with the above-mentioned neutralized material, if necessary. Here, as other resins, for example, polyvinyl alcohol resins such as polyvinyl alcohol and modified polyvinyl alcohol, albumin, gelatin, casein, starch, gum arabic, cellulose derivatives such as methylcellulose and hydroxyethylcellulose, poly (meth) acrylamide, polyvinyl Nonionic water-soluble resin such as pyrrolidone; anionic water-soluble resin such as carboxymethyl cellulose (CMC), sodium poly (meth) acrylate, sodium alginate, water-soluble polyester; cationized starch, cationized poly (meth) acrylamide , A cationic water-soluble resin such as a cationized polyamide resin; SBR latex,
Water-dispersible resins such as NBR latex, vinyl acetate emulsion, ethylene-vinyl acetate copolymer emulsion, (meth) acrylate ester emulsion, vinyl chloride emulsion and the like. Among them, it is preferable to use a polyvinyl alcohol resin in combination from the viewpoint of workability when forming the ink receiving layer. The amount of the polyvinyl alcohol resin used is preferably 500 parts by weight or less based on 100 parts by weight of the neutralized product of the maleic anhydride copolymer.

In forming the ink receiving layer, a filler such as silica, clay, talc, diatomaceous earth, zeolite, calcium carbonate, alumina, zinc oxide, and satin white (white pigment) can be used in combination. . Further, various additives such as a dispersed fluorescent dye, a pH adjuster, an antifoaming agent, a lubricant, a preservative, and a surfactant can be used in combination.

On the other hand, as the support constituting the recording medium in the present invention, any known support which is transparent or opaque can be used. As a transparent support,
For example, films, sheets, highly transparent papers and the like of polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polycarbonate, polyimide, cellophane, celluloid and the like can be mentioned. Examples of the opaque support include general paper, pigment-coated paper, cloth, metal foil, synthetic paper, opaque synthetic resin-based films and sheets.

The recording medium of the present invention can be obtained by providing an ink receiving layer comprising a neutralized maleic anhydride copolymer on a support. As a method for providing the ink receiving layer on the support, a known method can be used. An aqueous solution of a neutralized product of a maleic anhydride copolymer or an aqueous solution of a mixture of the maleic anhydride copolymer and another resin or a filler or an aqueous dispersion thereof is used. The method of applying and impregnating the liquid on the support by usual coating means such as a size press, an air knife coater, a roll coater, a bar coater, a blade coater, or forming a coat layer on one or both surfaces of the support is used. it can.

Further, the support may be coated with an adhesive resin, and a neutralized maleic anhydride copolymer may be coated thereon. As the adhesive resin used in this case,
For example, a composition of a polyurethane and an isocyanate, a rubber-based adhesive, an emulsion-based adhesive, and the like can be given. The content of the neutralized product of the maleic anhydride copolymer in the recording medium used in the present invention is not particularly limited,
Usually, it is 100 g / m ² or less.

In the ink jet recording method according to the present invention, the method of forming an image on a recording medium is not particularly limited, and it can be carried out in the same manner as a conventional ink jet recording method. Further, as the ink used for recording, those conventionally used in an ink jet recording method can be used.

In the present invention, the recording medium after image formation is heat-treated at a temperature of 80 ° C. or higher. By such heat treatment, ammonia is released from the neutralized product of the maleic anhydride copolymer to form an acid anhydride group. Therefore, it is considered that the hydrophilicity of the resin forming the ink receiving layer is reduced, and as a result, the water resistance of the recorded image is improved. Heat treatment is 8
It is necessary to carry out at a temperature of 0 ° C. or more, and 100 to 16
It is preferably carried out at a temperature in the range of 0 ° C. If the heat treatment temperature is lower than 80 ° C., the water resistance of the recorded image is not sufficiently improved. The time required for the heat treatment varies depending on the temperature at which the heat treatment is performed, but is usually 30 seconds to 10 minutes.

In the present invention, the heat treatment of the recording medium after the image formation is performed simply by leaving the recording medium after the image formation under a predetermined temperature atmosphere using a drier, a gear oven or the like. Can be. The heat treatment can be performed under normal pressure, reduced pressure or the like. In the heat treatment, it is preferable to reduce the amount of coexisting moisture, for example, by lowering the humidity.

[0038]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited to these examples. In the examples, the water resistance of a recorded image obtained by inkjet recording was evaluated by the following method. That is, a bubble jet color printer, B
Black using JC-455J (manufactured by CANON)
Color ink jet recording (printing) is performed using four types of inks of yellow, red and blue. The obtained recording medium is immersed in water for 1 minute, and the printed portion after taking out is observed to see whether the printed portion bleeds or dissolves, and is evaluated according to the following three grades. Evaluation ：: No change in the printed portion. Δ: The printed portion slightly bleeds, but does not dissolve. ×: The printed portion was melted, and the print was not legible.

Reference Example 1 An autoclave having an internal volume of 1 liter equipped with a stirrer was
Under a nitrogen atmosphere, 307.4 g of acetone and 18.5 g (0.33 mol) of isobutylene were charged, and the internal temperature was increased to 70 ° C.
The temperature rose. Next, 29.4 g (0.3 mol) of separately prepared maleic anhydride, 20.0 g (0.2 mol) of methyl methacrylate, and 2,2′-azobis (2-methylbutyronitrile) were added to the obtained solution. 1.92 g (0.01
Mol) and 100 g of acetone were continuously charged over 4 hours, and further polymerized at 70 ° C. for 1 hour.

After the completion of the polymerization reaction, the reaction mixture in the autoclave was taken out, air-dried overnight, and vacuum-dried at 90 ° C. to obtain 63.2 g of maleic anhydride copolymer A. ¹ H-N
As a result of MR analysis, it was found that the maleic anhydride unit, isobutylene unit and methyl methacrylate unit in the maleic anhydride copolymer A had a composition molar ratio of 1: 1: 0.65.

The properties of the obtained maleic anhydride copolymer A are shown below. (1) Average molecular weight (determined as a molecular weight in terms of polystyrene by GPC) Number average molecular weight = 13,200 Weight average molecular weight = 30,800 (2) Acid value: 467 mg KOH / g (3) Infrared absorption spectrum (ν: cm ^-1 ) 1380 (derived from isobutylene unit), 1460 (derived from isobutylene unit), 1770 (derived from maleic anhydride unit), 1860 (derived from maleic anhydride unit), 1
740 (derived from n-methyl methacrylate unit)

Reference Example 2 An autoclave equipped with a stirrer and having a volume of 1 liter was prepared.
Under a nitrogen atmosphere, 349.5 g of ethylbenzene, 39.2 g (0.4 mol) of maleic anhydride and isobutylene 3
3.7 g (0.6 mol) was charged, and the internal temperature was raised to 100 ° C. Then, the solution obtained was prepared separately from 2,
2'-azobis (2-methylbutyronitrile) 1.54
g (0.08 mol) and methyl ethyl ketone 61.6
g of the solution was continuously charged over 4 hours, and further polymerized at 100 ° C. for 1 hour.

After the completion of the polymerization reaction, the reaction mixture in the autoclave was taken out, and the precipitated polymer was separated by filtration by suction filtration, and then dried in vacuo at 90 ° C. to obtain 60.8 g of maleic anhydride copolymer B. Obtained. As a result of ¹ H-NMR analysis, it was found that the composition molar ratio of the maleic anhydride unit and the isobutylene unit in the maleic anhydride copolymer B was 1: 1.

The physical properties of the obtained maleic anhydride copolymer B are shown below. (1) Average molecular weight (determined by GPC as a molecular weight in terms of polystyrene) Number average molecular weight = 14,300 Weight average molecular weight = 28,900 (2) Acid value: 710 mg KOH / g (3) Infrared absorption spectrum (ν: cm ^-1 ) 1380 (derived from isobutylene unit), 1460 (derived from isobutylene unit), 1770 (derived from maleic anhydride unit), 1860 (derived from maleic anhydride unit)

Example 1 10.0 g of the maleic anhydride copolymer A obtained in Reference Example 1
0.85 g of ammonia (an amount equivalent to neutralize the acid anhydride groups in the maleic anhydride copolymer A by 60%:
The solution was added to 44.3 g of an aqueous solution containing (calculated from the above acid value), heated to 90 ° C. and stirred, and completely dissolved in 1 hour to form a transparent aqueous solution (hereinafter, this aqueous solution is abbreviated as aqueous solution A). Do). The concentration of the neutralized product of the maleic anhydride copolymer A in the aqueous solution A is 20% by weight.

The aqueous solution A obtained above was coated on a polyester film (OHP film, manufactured by Plus Co., Ltd.) with a thickness of 50 μm using a bar coater, and dried with a hot air dryer at 105 ° C. for 5 minutes. Then, a recording medium was obtained. After ink jet recording was performed by the above method, heat treatment was performed by leaving the internal temperature in a hot air dryer set at 140 ° C. for 3 minutes, and the water resistance of the recorded image was evaluated. Table 1 shows the results. When the recorded image after the heat treatment was visually observed, all the four colors of black, yellow, red, and blue showed the same coloring tendency, and only a specific color was not emphasized. No fading due to the heat treatment was observed.

Examples 2 and 3 10 of aqueous solution A used in Example 1 and polyvinyl alcohol [PVA-217 (trade name) manufactured by Kuraray Co., Ltd .: polymerization degree 1700, saponification degree 88 mol%] separately prepared % Aqueous solution (hereinafter, abbreviated as PVA aqueous solution) was mixed at a ratio shown in Table 1, and 50 μm was mixed using a bar coater.
After coating on polyester film with thickness of 105 ℃
Was dried for 5 minutes with a warm air dryer to obtain a recording medium. Ink jet recording was carried out by the above method, and heat treatment was carried out by leaving the inside of the apparatus in a hot air drier set at 140 ° C. for 3 minutes to evaluate the water resistance of the recorded image. Table 1 shows the results. In addition, when the recorded image after the heat treatment was visually observed, all the four colors of black, yellow, red, and blue showed the same coloring tendency. No fading due to the heat treatment was observed.

Example 4 10.0 g of the maleic anhydride copolymer B obtained in Reference Example 2
1.32 g of ammonia (an amount equivalent to neutralizing the acid anhydride groups in the maleic anhydride copolymer B by 60%)
Into 46.6 g of an aqueous solution containing, heated to 90 ° C.,
When the mixture was stirred, it was completely dissolved in 1 hour to form a transparent aqueous solution (hereinafter, abbreviated as aqueous solution B). The concentration of the neutralized product of the maleic anhydride copolymer B in the aqueous solution B is 20% by weight. The aqueous solution B obtained above and the PVA aqueous solution were mixed at a ratio shown in Table 1 and applied to a polyester film with a thickness of 50 μm using a bar coater, and then a hot air dryer at 105 ° C. for 5 minutes. It was dried to obtain a recording medium. Perform ink jet recording by the above method,
Heat treatment was performed by leaving the inside of the apparatus in a hot air dryer set at 140 ° C. for 3 minutes to evaluate the water resistance of the recorded image. Table 1 shows the results. In addition, when the recorded image after the heat treatment was visually observed, all the four colors of black, yellow, red, and blue showed the same coloring tendency. No fading due to the heat treatment was observed.

Comparative Examples 1-4 After ink jet recording was performed in Examples 1-4,
The water resistance of the recorded image was evaluated without heat treatment. Table 1 shows the results.

[0050]

[Table 1]

[0051]

According to the ink jet recording method of the present invention, a recorded image having excellent water resistance can be formed.

 ──────────────────────────────────────────────────続 き Continued from the front page (72) Inventor Masao Ishii 36 Towada, Kamisu-cho, Kashima-gun, Ibaraki Pref. Kuraray Co., Ltd.

Claims (1)

[Claims] 1. An ink jet recording method for performing recording by ejecting ink onto a recording medium to form an image on the recording medium, comprising a maleic anhydride unit represented by the formula (1): (Wherein, R ¹ and R ² each represent a hydrogen atom or a carbon atom 1
Represents 8 alkyl group, R ³ is a hydrogen atom, 1 to carbon atoms
8 represents an alkyl group, a cycloalkyl group having 3 to 12 carbon atoms or a phenyl group) and a structural unit represented by the formula (2): (Wherein R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ represents an alkyl group having 1 to 18 carbon atoms or a cycloalkyl group having 3 to 12 carbon atoms). When the ratio is [maleic anhydride unit]: [formula (1)
[Structural unit represented by formula]: [Structural unit represented by formula (2)] = 1: 0.8 to 1.2: Neutralized product obtained by reacting a copolymer with 1.2 to 2 with ammonia An ink jet recording method comprising using a recording medium having an ink receiving layer formed of a support on a support, and heat-treating the recording medium after image formation at a temperature of 80 ° C. or higher.