JPH1016381A - 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 shelf stability, uniformity of an image, resolving degree, curling resistance and fingerprint resistance by containing modified polyvinyl alcohol having a cationic radical. SOLUTION: As a method for introducing a cationic radical into PVA, cationic vinyl monomer such as N,N-dimethylaminoalkyl acrylamide or its quaternary salt and N,N-dimethylaminoalkyl acrylate or its quaternary salt is copolymerized with vinyl acetate and thereafter saponification is performed. Further, cationic vinyl monomer is reacted with PVA by Michael addition, or glycidyl compound having a cationic radical such as 2,3-epoxymethyltrimethyl ammonium chloride is reacted with PVA.

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]

According to a first aspect of the present invention, there is provided a treating agent for an ink jet recording medium, comprising a modified polyvinyl alcohol having a cationic group.
VA).

According to a second aspect, in the first aspect, the modified PVA is a cationically modified PVA obtained by Michael addition of a cationic vinyl compound to 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 N, N-dimethylaminoalkylacrylamide or a quaternary salt thereof to PVA.

According to a fourth aspect, in the first aspect, the modified PVA is a modified PVA obtained by subjecting PVA to an addition reaction of 2,3-epoxymethyldimethylamine or a quaternary salt thereof.

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]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The treating agent for an ink jet recording medium of the present invention contains a modified PVA having a cationic 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 ratio of the cationic group of the modified PVA used in the present invention is preferably 2.0 to 40 mol%, more preferably 4.0 to 30 mol%. 2.0 mol%
If it is less than 1, sufficient ink absorbency and resolution cannot be obtained. On the other hand, if it exceeds 40 mol%, the production is difficult and the production cost is high.

As a method for introducing a cationic group into PVA, a method for introducing a cationic vinyl such as vinyl acetate and N, N-dimethylaminoalkyl acrylamide or a quaternary salt thereof or N, N-dimethylaminoalkyl acrylate or a quaternary salt thereof is used. Saponification method after copolymerization of monomer, P
A method of reacting the cationic vinyl monomer with VA by a Michael addition reaction or a method of reacting PVA with a glycidyl compound having a cationic group such as 2,3-epoxymethyltrimethylammonium chloride can be used.

Among them, N, N-dimethylaminoalkylacrylamide or a quaternary salt thereof, or 2,3-epoxymethyldimethylamine or a quaternary salt thereof is used for PVA in that a material having a high modification rate is easily obtained. 2,
A method of reacting 3-epoxymethyltrimethylammonium chloride is desirable.

The alkyl group such as N, N-dimethylaminoalkylacrylamide has preferably 1 to 4 carbon atoms.

In introducing a cationic group into these PVAs, if necessary, two or more methods or agents may be used in combination, and so-called amphoteric modified PVA having an anionic group and a cationic group is also used in the present invention. Corresponds to modified PVA.

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, and 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, cardboard 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 solution 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.

[0027] The coating amount of the ink receiving layer is 0.
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 ink 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 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. Containing a polyhydric alcohol having a drying prevention effect.

[0030]

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 PVA (degree of polymerization 2,5) was placed in a 4-liter horizontal blender.
00, saponification degree 98.8 mol%) 200 parts, 25% -N
An aOH aqueous solution (50 g) and a 75% -N, N-dimethylaminopropylacrylamide methyl chloride quaternary salt aqueous solution (420 g) were added, and the mixture was stirred at 50 ° C for 7 hours.

The obtained product was purified with methanol and then dried to obtain a powdery product. As a result of analyzing this product by NMR, the cationic group modification rate was 22.5 mol%.

Production Example 2 PVA (degree of polymerization 1,7) was placed in a 4-liter horizontal blender.
00, saponification degree 98.5 mol%) 200 parts, 25% -N
35 g of aOH aqueous solution and 193 g of 74% aqueous solution of 2,3-epoxymethyltrimethylammonium chloride
Was added and stirred at 70 ° C. for 4 hours.

The obtained product was purified with methanol and then dried to obtain a powdery product. This was analyzed by NMR, and as a result, the modification ratio of the cationic group was 12.3 mol%.

Production Example 3 PVA (degree of polymerization 2,5) was placed in a 4-liter horizontal blender.
00, degree of saponification 98.8 mol%) 440 parts, 30% -N
20 parts of an aOH aqueous solution and 48 parts of a 50% -acrylamide aqueous solution were added, and the mixture was stirred at 60 ° C for 4 hours. Then 50
% -NaOH (100 parts) was added, and the mixture was hydrolyzed at 90 ° C. for 1 hour.

Next, 400 g of an aqueous solution of 70% -N, N-dimethylaminopropylacrylamide methyl chloride quaternary salt was added, and the mixture was stirred at 50 ° C. for 7 hours.

The obtained product was purified with methanol and then dried to obtain a powdery product. As a result of an NMR analysis of this product, the modification ratio of the cationic group was 8.1 mol% and the modification ratio of the carboxyl was 2.3 mol%.

[0038] 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 Discharge volume suitable for discharge liquid: 30 pl Recording density: 400 DPI Maximum single-color ink application amount: 7.4 nl / mm ^2. Maximum color overlap number: 3 colors
.

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

Evaluation Items (1) Ink Absorbency After recording on full dots of three colors of yellow, cyan and magenta, the recording was left for 30 seconds at room temperature (20 ° C., 65% RH) 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 printing on full dots of three colors of yellow, cyan and magenta, warm air (100 ° C., air speed 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,
X indicates bleeding and thickening of the character and the image quality was remarkably inferior, ○ indicates no change, and Δ indicates a medium level. What was done was XX.

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

(6) Resolution A recorded image is projected on a screen by OHP, and a clear and easy-to-view image with high contrast is obtained. 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) Curl 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 class 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 “△”, and the one with sharply visible fingerprint was marked with “×”. .

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.

[0053]

[Table 1]

[0054]

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 a cationic group. 2. The processing agent for an inkjet recording medium according to claim 1, wherein the modified polyvinyl alcohol is a cation-modified polyvinyl alcohol obtained by Michael addition of a cationic vinyl compound to polyvinyl alcohol. . 3. The modified polyvinyl alcohol, wherein the modified polyvinyl alcohol is a modified polyvinyl alcohol obtained by Michael addition of N, N-dimethylaminoalkylacrylamide or a quaternary salt thereof to polyvinyl alcohol.
The treatment agent for an inkjet recording medium according to claim 1. 4. The modified polyvinyl alcohol according to claim 1, wherein the modified polyvinyl alcohol is a modified polyvinyl alcohol obtained by adding 2,3-epoxymethyldimethylamine or a quaternary salt thereof to polyvinyl alcohol. 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.