JPH1016380A - Treatment agent for ink-jet recording medium and ink-jet recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide various characteristics such as absorptivity of ink, blocking resistance, image density, long-term self stability, uniformity of an image, resolving degree, curing resistance and fingerprint resistance with a good balance by containing modified polyvinyl alcohol having an anionic and/or nonionic radical. SOLUTION: The treatment agent for ink-jet recording media contains modified polyvinyl alcohol(PVA) having an anionic and/or nonionic radical. Modified PVA is obtained by reacting a vinyl compound with vinyl alcohol by Michael addition or obtained by performing Michael addition for both and thereafter partially or completely hydrolyzing the reaction product. In the case of making a medium to be recorded, firstly, a treatment agent is dissolved in water or alcohol and other suitable organic solvent to regulate coating liquid. The obtained coating liquid is applied to the surface of base material by e.g. a roll coater. Thereafter, the surface is dried to obtain an ink-jet recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording medium suitably used for ink jet recording and a treating agent used for obtaining the same.

[0002]

2. Description of the Related Art As a recording medium used for ink-jet recording, a coating medium containing finely divided silica and a water-soluble binder such as polyvinyl alcohol on a base paper as described in Japanese Patent Publication No. 3-26665 has conventionally been used. Recording paper provided with a layer, glossy paper in which a film containing a polyvinyl alcohol having a saponification degree of 50 to 90 mol% and a crosslinking agent is formed on a cast-coated paper as described in JP-B-3-25352, JP-A-3-13993 discloses an overhead recording sheet provided with a hydrophilic film comprising a mixture of a water-soluble polyvinyl alcohol, a water-insoluble polyvinyl alcohol and a water-dispersible polyester on a polyester film. Has been used.

[0003]

However, with the recent improvements in the performance of the ink jet recording apparatus, such as high-speed recording and multi-color printing, higher and broader characteristics are required for the ink jet recording medium. It is becoming. That is, (1) high absorption capacity of ink (large absorption capacity and quick absorption time) (2) high optical density of dots and no blur around the dots (3) dot shape is close to a perfect circle, (4) Changes in characteristics are small due to changes in temperature and humidity, and no curling occurs. (5) No blocking occurs. (6) Images are stable for long-term storage and do not deteriorate. It is required to satisfy the characteristics at the same time.

[0004] However, it is difficult to satisfy these various properties at the same time, and the prior art has not yet succeeded in simultaneously satisfying these properties. For example, the above-described conventional recording media all have reached a certain level in terms of dot shape and blocking resistance, but have insufficient ink absorption capacity, and therefore have a high image density portion, that is, ink. There is a tendency to cause image stains and density unevenness due to overflow of ink in portions where the amount of ejection is large.
In particular, in the case of color printing, there is a problem in that color contamination occurs due to color mixing at the boundary between different colors.

As described above, as the recording speed, the image density, and the colorization progress, the deterioration of the image quality due to poor ink fixing becomes a serious problem.

On the other hand, a recording sheet having an ink receiving layer mainly composed of polyvinylpyrrolidone described in JP-B-3-29596 has a relatively good ink absorption capacity at room temperature and normal humidity, but has a relatively high ink absorption capacity. Under a high humidity condition, the ink dries very slowly, and has a drawback that blocking easily occurs. Further, there is also a problem that the mechanical strength of the recorded image is weak and a scratch is easily formed.

An object of the present invention is to solve these problems and to provide an ink jet recording medium which satisfies the above-mentioned various properties at the same time in a well-balanced manner, and a processing agent for the ink jet recording medium used for obtaining the same. That is.

[0008]

The treating agent for an ink jet recording medium according to claim 1 is a modified polyvinyl alcohol having an anionic and / or nonionic group (hereinafter referred to as a modified polyvinyl alcohol).
Polyvinyl alcohol is abbreviated as PVA).

According to a second aspect of the present invention, in the first aspect, the modified PVA is obtained by Michael addition of a vinyl compound to PVA, or is obtained by partial or complete hydrolysis after Michael addition. Modified PVA.

A third aspect of the present invention is the modified PVA according to the first aspect, wherein the modified PVA is obtained by Michael addition of acrylonitrile or acrylamide to PVA.
A.

A fourth aspect of the present invention is the modified PVA according to the first aspect, wherein the modified PVA is obtained by adding Michael to acrylonitrile or acrylamide to PVA and then partially or completely hydrolyzing the modified PVA.

The ink jet recording medium of claim 5 is
The treatment agent for an ink jet recording medium according to any one of claims 1 to 4 is applied to a surface of a substrate.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The treating agent for an ink jet recording medium of the present invention contains a modified PVA having an anionic and / or nonionic group.

The degree of polymerization of the modified PVA used in the present invention is not particularly limited, but is preferably from 200 to 8,000.
300-4,000 is more preferred. If the degree of polymerization is less than 200, the film strength is low, which is not suitable for the purpose of the present invention. If the degree of polymerization exceeds 8,000, handling properties such as the viscosity of the coating liquid will increase.

The modification rate of the anionic and / or nonionic group of the modified PVA is preferably 2.0 to 40 mol%, more preferably 4.0 to 30 mol%. If it is less than 2.0 mol%, sufficient ink absorption and resolution cannot be obtained. On the other hand, if it exceeds 40 mol%, the production is difficult and the production cost is high.

Examples of the type of the anionic group include a carboxyl group, a sulfone group, and a phosphoric acid group.
A carboxyl group and a sulfone group are desirable from the viewpoint of ease of production.

The carboxyl group-modified P used in the present invention
VA can be obtained, for example, by copolymerizing vinyl acetate and itaconic acid or maleic acid and then saponifying.
So-called copolymer-modified PVA and so-called post-modified PVA in which a carboxyl group is directly introduced into PVA can be used. As a method of introducing a carboxyl group into PVA by post-modification, a method of monoesterifying PVA with maleic anhydride or the like, a method of substituting monochloroacetic acid or the like with PVA, a method of performing a Michael addition reaction of acrylic acid or the like with PVA, Similarly, there is a method in which acrylonitrile, acrylamide and the like are subjected to a Michael addition reaction and then hydrolyzed. Among these, from the viewpoint that a reaction rate is high and a high modification rate can be obtained, a method in which acrylonitrile or acrylamide is added to Michael and then hydrolyzed is desirable.

On the other hand, as a method for introducing a sulfone group into PVA, for example, vinyl acetate and vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid (hereinafter, referred to as PVA) , Abbreviated as AMPS) or the like, followed by saponification, vinyl sulfonic acid or a salt thereof, A
There is a method of Michael-adding MPS or a salt thereof to PVA. Among them, AMPS or a salt thereof is PV
A method of adding Michael to A is desirable.

Next, an example of nonionic modification will be described.

The types of nonionic groups include nitrile groups,
Examples include an amide group and an ester group.

Examples of a method for introducing an amide group into PVA include a method in which acrylamide and vinyl acetate are copolymerized and then saponified, a method in which acrylamide is added to PVA by a Michael addition reaction, and the like. From the viewpoint that a product having a high modification rate can be obtained, a method of subjecting PVA to an addition reaction of acrylamide with Michael is desirable.

In addition, a method of performing a Michael addition reaction of PVA with an acrylate such as methyl acrylate, a method of performing a Michael addition reaction of mono- or diacrylate of polyethylene glycol, and a substitution reaction of mono- or diglycidyl ether of polyethylene glycol. There are methods.

In introducing an anion and / or a nonionic group into these PVAs, two or more methods or agents may be used in combination. In addition, even with one kind of drug, 2
More than one type of modification can also be performed.

As an example of performing two or more types of denaturation with one type of agent, there is a method in which acrylamide is subjected to a Michael addition reaction with PVA and then partially hydrolyzed with an alkali. Thereby, an anionic group (carboxyl group) and a nonionic group (amide group) can be simultaneously introduced.

The ink-jet recording medium of the present invention is a recording medium having an ink receiving layer on the surface of a substrate by coating the surface of the substrate with the treatment agent containing the modified PVA. Various binders, fillers, and additives can be used together within a range that does not hinder achievement of the object of the present invention.

Examples of the binder include conventionally known starch, cationized starch, casein, gelatin, acrylic resin, maleic anhydride resin, melamine resin, urea resin, SBR latex, sodium alginate, polyvinylpyrrolidone and the like. It is not limited to.

Examples of fillers include silica, alumina, aluminum silicate, magnesium silicate, basic magnesium carbonate, talc, clay, calcium carbonate,
Examples include, but are not limited to, titanium oxide, zinc oxide, and plastic pigments such as polyethylene, polystyrene, and polyacrylate.

Examples of additives include various surfactants, dye fixatives (waterproofing agents), defoamers, antioxidants, fluorescent brighteners, ultraviolet absorbers, dispersants, viscosity adjusters, pH adjusters. Agent,
Fungicides and plasticizers. These additives may be arbitrarily selected according to the purpose.

The base material constituting the recording medium of the present invention includes paper such as high quality paper, medium quality paper, art paper, bond paper, recycled paper, baryta paper, cast coated paper, corrugated paper, and the like.
Polyethylene terephthalate, diacetate, triacetate, cellophane, celluloid, polycarbonate, polyimide, polyvinyl chloride, polyvinylidene chloride, polyacrylate and other plastic films or plates, glass plates, or cotton, rayon, acrylic, nylon, silk, polyester, etc. Cloth can be used. These substrates are appropriately selected according to various conditions such as the recording purpose of the recording medium, the use of the recorded image, and the adhesion to the composition coated on the recording medium.

In preparing the recording medium of the present invention, the above-mentioned treating agent is first dissolved or dispersed in water or an alcohol or another suitable organic solvent together with other additives as necessary, and the coating solution is prepared. adjust.

The obtained coating liquid can be used, for example, by a roll coater method, a blade coater method, an air knife coater method, a gate roll coater method, a bar coater method, a size press method, a spray coat method, a gravure coater method, a curtain coater method and the like. On the surface of the base material. Thereafter, drying is performed using, for example, a hot-air drying furnace or a hot drum to obtain the recording medium of the present invention. Further, if necessary, a super calender treatment or the like may be performed to smooth the ink receiving layer or improve the surface strength.

The coating amount of the ink receiving layer is 0.1% in total.
It is preferably from ² to 50 g / m2, more preferably from 0.2 to 50 g / m2.
It is in the range of 20 g / m ² . Coating amount is 0.2 g / m ²
Is less than the case where the ink receiving layer is not provided, there is no effect in terms of the coloring property of the paint.
If the thickness is more than / m ² , powder fall of the coat layer occurs, which is not preferable. When the coating amount is represented by the thickness, the coating amount is preferably in the range of 0.5 to 100 μm in thickness. However, when the coating amount is small, a part of the substrate may be exposed on the surface.

Any known inks can be used for ink-jet recording on the recording medium of the present invention. Further, as a recording agent, a direct dye, an acid dye, a basic dye, a reactive dye, a water-soluble dye represented by an edible dye can be used, and a normal ink jet recording agent can be used without any particular limitation. it can. Such water-soluble dyes are generally present in conventional inks at about 0.1%.
It is used in a proportion occupying up to 20% by weight, and this proportion may be the same in the present invention.

The solvent used in the above ink is water or a mixed solvent of water and a water-soluble organic solvent. Particularly preferred is a mixed solvent of water and a water-soluble organic solvent, and the ink is used as a water-soluble organic solvent. Containing a polyhydric alcohol having a drying prevention effect.

[0035]

EXAMPLES Hereinafter, the treating agent for an ink jet recording medium of the present invention and the ink jet recording medium obtained by using the same will be described in more detail with reference to Examples. In the following description, parts and% are based on weight unless otherwise specified.

Production Example 1 75 parts of vinyl acetate, 500 parts of methanol, 4.85 parts of itaconic acid, 110 parts of NaOH, and 0.3 part of azobisisobutyronitrile were charged into a separable flask and heated at 70 ° C.
For 9 hours. At this time, the polymerization rate was 81%.
After removing unreacted vinyl acetate, 1/10 of the theoretical amount of NaOH was added, and the mixture was saponified at 40 ° C. for 5 hours. The polymerization degree of the obtained carboxy-modified PVA was 1,200 and the saponification degree was 96.3 mol%. In addition, as analyzed by NMR, the carboxyl modification rate was 3.3 mol%.

Production Example 2 PVA (degree of polymerization 1,700, degree of saponification 99.1 mol%)
40 parts, maleic anhydride 15 parts, sodium hydrogen carbonate 4
Parts, 350 parts of toluene were charged into a separable flask,
Stirred at 70 ° C. for 5 hours. After filtering the obtained product, it was purified several times with methanol and acetone. In addition, the carboxyl modification rate obtained from the colloid equivalent value of this was 7.3 mol%.

Production Example 3 PVA (degree of polymerization: 50) was placed in a 4-liter horizontal blender.
0, saponification degree 88.2 mol%) 490 parts, NaOH 20
0 parts, 420 parts of a 50% -monochloroacetic acid aqueous solution and 200 parts of isopropyl alcohol were added, and the mixture was stirred at 60 ° C. for 8 hours. The obtained product was purified with methanol, dried, and analyzed by colloid titration. As a result, the carboxyl modification rate was 16.2 mol%.

Production Example 4 PVA (degree of polymerization 2.5, 5) was placed in a 4-liter horizontal blender.
00, degree of saponification 98.8 mol%) 440 parts, 30% -N
200 parts of an aOH aqueous solution and 484 parts of a 50% -acrylamide aqueous solution were added, followed by stirring at 60 ° C. for 8 hours. Next, 100 parts of 50% -NaOH was added, and hydrolysis was performed at 90 ° C. for 1 hour.

When the obtained powder was analyzed by NMR,
The carboxyl modification rate was 29.3 mol% and the amide modification rate was 0.0 mol%.

Preparation Example 5 Preparation Example 4 was repeated except that 250 parts of acrylonitrile were used instead of 484 parts of the 50% aqueous acrylamide solution.
Denaturation was carried out in the same manner as described above.

When the obtained powder was analyzed by NMR,
The carboxyl modification rate was 37.6 mol%, and the cyano modification rate was 0.0 mol%.

Production Example 6 PVA (polymerization degree: 1,7) was added to a 4-liter horizontal blender.
00, degree of saponification 98.5 mol%) 440 parts, 50% -N
280 parts of aOH aqueous solution and 50% -AMPS aqueous solution 8
28 parts were added and stirred at 80 ° C. for 7 hours.

When the obtained powder was analyzed by NMR,
The modification ratio of the sulfone group was 14.3 mol%.

Production Example 7 PVA (polymerization degree 5, 0) was placed in a 4-liter horizontal blender.
00, saponification degree 98.2 mol%) 440 parts, 30% -N
70 parts of an aOH aqueous solution and 284 parts of a 50% -acrylamide aqueous solution were added, and the mixture was stirred at 60 ° C for 4 hours. Then 5
125 parts of 0% -NaOH was added, and the mixture was hydrolyzed at 70 ° C. for 1 hour.

Next, 460 parts of a 50% -AMPS sodium salt aqueous solution was added, and the mixture was stirred at 80 ° C. for 4 hours.

When the obtained powder was analyzed by NMR,
The carboxyl modification rate was 12.3 mol%, the sulfone group modification rate was 6.5 mol%, and the amide modification rate was 4.3 mol%.

Production Example 8 PVA (polymerization degree 1,7) was placed in a 4-liter horizontal blender.
00, degree of saponification 98.8 mol%) 440 parts, 30% -N
200 parts of an aOH aqueous solution and 484 parts of a 50% -acrylamide aqueous solution were added, followed by stirring at 60 ° C. for 8 hours. Next, 50 parts of 50% -NaOH was added, and the mixture was hydrolyzed at 70 ° C. for 1 hour.

When the obtained powder was analyzed by NMR,
The carboxyl modification rate was 16.3 mol% and the amide modification rate was 10.5 mol%.

Production Example 9 PVA (degree of polymerization 2.5, 5) was placed in a 4-liter horizontal blender.
00, degree of saponification 98.8 mol%) 440 parts, 30% -N
30 parts of an aOH aqueous solution and 484 parts of a 50% -acrylamide aqueous solution were added, and the mixture was stirred at 25 ° C for 7 hours.

When the obtained powder was analyzed by NMR,
The amide modification rate was 26.5 mol% and the carboxyl modification rate was 0.0 mol%.

[0052] 95 parts of water the resulting polymer 5 parts in Production Example 1 was added with stirring a mixture of isopropyl alcohol 5 parts dissolution. Using a wire bar, the obtained coating liquid was applied to a high-quality paper (Silver Ring, manufactured by Sanyo Kokusaku Pulp) so that the coating thickness after drying was 4 microns, and then dried at 70 ° C. for 10 minutes. The recording medium of the present invention was obtained by processing with a super calender. Color recording was performed on the recording medium under the following conditions by using an ink jet recording apparatus in which the ink having the following composition was foamed by thermal energy to discharge the ink.

Ink composition dye 3 parts Diethylene glycol 15 parts Water 82 parts
.

Dye T: C.I. I. Direct Yellow # 86 M: C.I. I. Reactive Red # 23 C: C.I. I. Acid Blue # 9 Bk: C.I. I. Reactive Black # 31
.

Recording conditions Discharge frequency: 3 KHz Appropriate volume of discharge liquid: 30 pl Recording density: 400 DPI Maximum amount of single-color ink applied: 7.4 ml / mm ^2. Maximum number of superimposed colors: 3 colors
.

The following items were evaluated for the obtained color print samples.

Evaluation Item (1) Ink Absorbability After recording on full dots of three colors of yellow, cyan and magenta, the ink was left at room temperature (20 ° C., 65% RH) for 30 seconds and then touched the recorded image. At times, it was determined whether or not the ink was taken into the ink receiving layer and did not adhere to the finger.し な い indicates no attachment, X indicates attachment, and Δ indicates the middle.

(2) Blocking resistance After recording on full dots of three colors of yellow, cyan and magenta, warm air (100 ° C., air velocity 1 m / sec) is applied to the recording surface for 1
After exposure for 0 seconds, clear pocket (Lion, polypropylene film) on the recorded image at a pressure of 40 g / cm ²
Was determined based on whether or not this film could be easily peeled when laminated.場合 indicates that the film can be easily peeled, X indicates that the film requires considerable force, and 、 indicates the middle.

(3) Image Density The black (Bk) image density of a solid printed image using the printer described above was measured using a Macbeth densitometer RD-918.
Was evaluated using

(4) Storage Property Each recording medium was stored under an environment of 35 ° C. and 90% RH.
After being stored for one day, it was stored for one day in an environment of 23 ° C. and 55% RH, and then evaluated using the above printer in an environment of 23 ° C. and 55% RH.

As compared with the recording medium before storage, ink overflow,
When the bleeding and character thickening occurred and the image quality was remarkably inferior, x was given, when there was no change, ○ was given, and in the middle, △ was given. Are XX.

(5) Image unevenness In the printed matter solid-printed using the above-described printer, the one in which the above-mentioned unevenness in density was not recognized was evaluated as ○, and the one in which the printed matter and the eyes could be confirmed visually from a distance of 50 cm. ×, intermediates between them were rated as Δ.

(6) Resolution A recorded image is projected on a screen by an OHP, and a clear and easy-to-view image with high contrast is obtained. O, bleeding or the like is caused, and the boundary between two different colors is blurred or pitched. When a line having a width of 1 mm and a thickness of 0.3 mm could not be clearly discriminated, the result was evaluated as x, and the middle thereof was evaluated as Δ.

(7) Curling Resistance The printed film was placed on an overhead projector (Model 4000) manufactured by Sumitomo 3M Limited. After 3 minutes, the lift of the corner was measured with a JIS first-grade metal scale. 10 mm was marked as Δ, and 10 mm or more was marked as x.

(8) Fingerprint resistance When the right thumb was pressed firmly against the printed film and projected by OHP, the mark with almost no visible fingerprint was marked with “O”, the one with slightly visible fingerprint was marked with “も の”, and the one with sharply visible fingerprint was marked with “X”. .

Examples 2 to 10 and Comparative Examples 1 to 3 Various recording media were prepared in the same manner as in Example 1.
Color recording was performed. As comparative examples, similar evaluations were made on commercially available recording paper and transparency films for inkjet. The contents of the recording medium and the evaluation results are shown below.

[0067]

[Table 1]

[0068]

According to the fifth aspect of the present invention, the ink jet recording medium of the present invention has an ink absorption capacity, blocking resistance, image density, long-term preservability, image uniformity, resolution, curling resistance, and fingerprint resistance. And other characteristics in a well-balanced manner, and is suitably used for inkjet recording regardless of the type of ink. Further, according to the processing agent for an inkjet recording medium of the first to fourth aspects, the inkjet recording medium can be easily obtained.

Claims (5)

[Claims] 1. A treating agent for an inkjet recording medium comprising a modified polyvinyl alcohol having an anionic and / or nonionic group. 2. The modified polyvinyl alcohol is obtained by Michael addition of a vinyl compound to polyvinyl alcohol, or modified polyvinyl alcohol obtained by partial or complete hydrolysis after Michael addition. The treatment agent for an inkjet recording medium according to claim 1. 3. The treatment agent for an inkjet recording medium according to claim 1, wherein the modified polyvinyl alcohol is a modified polyvinyl alcohol obtained by adding acrylonitrile or acrylamide to polyvinyl alcohol by Michael. 4. The modified polyvinyl alcohol according to claim 1, wherein the modified polyvinyl alcohol is a modified polyvinyl alcohol obtained by Michael addition of acrylonitrile or acrylamide to polyvinyl alcohol, and then partially or completely hydrolyzing. Processing agent for inkjet recording media. 5. An ink jet recording medium obtained by applying the treatment agent for an ink jet recording medium according to claim 1 to a surface of a substrate.