JP2750433B2 - Inkjet recording paper - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an ink jet recording sheet, and more particularly, to an ink jet recording sheet which is excellent in ink absorption capacity, has a high resolution, and forms a clear recorded image.

[Prior Art] The inkjet recording method is being applied to facsimile machines, various printers, and the like. Properties required for the recording material used in the ink jet recording method include a high ink absorption speed and a requirement that the diameter of the ink dot does not become larger than necessary.

As a method for improving such a defect, for example, Japanese Patent Application Laid-Open
As disclosed in JP 134291, it has been proposed that various polyvinyl alcohol (hereinafter abbreviated as PVA) resins be present in paper and / or in a coating layer.

[Problems to be Solved by the Present Invention] However, since the present inventors cannot always respond to the recent demand for high quality, it has been found that a higher-resolution and higher-resolution recording screen with higher ink absorption capacity can be obtained. It has become clear that there is a need to provide an inkjet recording paper that can be formed.

[Means for Solving the Problems] As a result of further studies, the present inventor has reported that a 4% aqueous solution of a PVA resin having an anionic group having a viscosity at 20 ° C. of 2 to 60 cps is applied to paper and / or coated. It has been found that the ink jet recording paper present in the layer can achieve the object, and the present invention has been completed.

The anionic group referred to in the present invention is typically a sulfonic acid group or a carboxyl group.

 Hereinafter, a specific description will be given.

 The sulfonic acid group-containing PVA is produced as follows.

A method for further saponifying a polymer obtained by polymerizing an olefin sulfonic acid such as ethylene sulfonic acid, allyl sulfonic acid, methallyl sulfonic acid or a salt thereof with a vinyl ester such as vinyl acetate in an alcohol or an alcohol / water mixed solvent. .

[R is an alkyl group, R 'is an alkylene group, M is hydrogen or an alkali metal, ammonium ion] and a vinyl ester such as vinyl acetate is copolymerized. How to
Examples of the sulfoalkyl malate include sodium sulfopropyl 2-ethylhexyl malate, sodium sulfopropyl tridecyl malate, and sodium sulfopropyl eicosyl malate.

[R ₁ hydrogen or a methyl group, R ₂ is a hydrogen or an alkyl group,
R 'and M are the same as defined above]
A method of copolymerizing acrylamide, for example, sodium salt of N-sulfoisobutyleneacrylamide with a vinyl ester such as vinyl acetate, and saponifying the resulting copolymer. More general formula A method of copolymerizing a sulfoalkyl (meth) acrylate, for example, sodium 2-sulfoethyl acrylate, with a vinyl ester such as vinyl acetate, and saponifying the resulting copolymer.

In the case of these copolymerizations, it is possible to introduce an optional third component such as an ethylenically unsaturated carboxylic acid alkyl ester, α-olefin, or alkyl vinyl ether.

A method in which PVA is treated with bromine and iodine and then heated in an aqueous sodium acid sulfite solution.

 A method of heating PVA in a concentrated aqueous sulfuric acid solution.

A method of acetalizing PVA with an aldehyde compound containing a sulfonic acid group.

And so on.

The sulfonic acid group may be in the form of a free acid or in the form of a sodium salt, a potassium salt, an ammonium salt or the like.

The content of the sulfonic acid group in the sulfonic acid group-containing PVA resin is 0.1 to 20 mol%, preferably 1 to 10 mol%.
Are suitable for the purpose of the present invention.

The degree of saponification is 40 to 100 mol%, preferably 60 to 100 mol%.
Is practical, and the viscosity of the 4% aqueous solution at 20 ° C. needs to be 2 to 60 cps, preferably 3 to 40 cps.
Those of the order of ps are useful.

On the other hand, as a method of introducing a carboxyl group into PVA, a method of copolymerizing with a monomer copolymerizable with a vinyl ester and saponifying a method of grafting PVA, or a method of graft-polymerizing a polyvinyl ester and saponifying a method of PVA Examples include a method by a chemical reaction.

Examples of the method include an unsaturated basic acid, an unsaturated dibasic acid, an anhydride thereof, or an ester thereof, such as an acrylic acid, which can be copolymerized with an organic acid vinyl ester such as vinyl formate, vinyl acetate, or vinyl propionate. Acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride, by saponifying a copolymer such as itaconic anhydride, or the above vinyl esters and acrylonitrile, methacrylonitrile, acrylamide, By saponifying a copolymer with methacrylamide, a target polyvinyl alcohol derivative having a carboxyl group in the molecule can be produced.

Examples of the method include a method in which polyvinyl ester such as PVA or polyvinyl acetate, acrylonitrile, acrylamide, or the like is graft-polymerized and saponified.

As a method, a dibasic acid such as maleic acid, fumaric acid, phthalic acid, oxalic acid, malonic acid, succinic acid, adipic acid or an anhydride thereof is reacted with PVA to introduce a carboxyl group by a single esterification reaction. Can be done.

The content of the carboxyl group in the carboxyl group-containing PVA resin is 0.1 to 20 mol%, preferably 1 to 10%.
Mole is preferred for the purposes of the present invention.

The degree of saponification is 40 to 100 mol%, preferably 60 to 100 mol%.
Is practical, and the viscosity of the 4% aqueous solution at 20 ° C. needs to be 2 to 60 cps, preferably 3 to 40 cps.
Those of the order of ps are useful.

In the present invention, as a method of incorporating a PVA-based resin having an anionic group in the inkjet recording paper,
A method of applying or impregnating the surface by spraying or side-pressing the ink jet recording paper made by a known method, or when manufacturing a known coated paper type ink jet recording paper, mixing in the coating paint, blade, air knife, Examples thereof include a method of applying with a coating machine such as a roll coater, and a method of internally adding at the time of making ink jet recording paper.

The anionic group-containing PV in an ink jet recording paper
The addition amount of the A resin usually 0.01 to 10 g / m ² is preferably
0.05-5 g / m ² is used. If it is less than 0.01 g / m ² , there is no effect of improving the ink absorption capacity and resolution, and if it is more than 10 g / m ² , the water resistance tends to decrease.

During the production of such recording paper, talc, kaolin, calcium carbonate, non-colloidal silica powder, recording paper having various fillers such as fine powder urea formalin resin filler, or non-colloidal silica powder, acid clay, clay, talc, calcium carbonate, Contains anionic group in recording paper etc. which have white pigment such as diatomaceous earth, titanium oxide, barium sulfate etc. as coating layer
By applying PVA, it is possible to obtain an ink jet recording paper having a high ink absorption capacity and a high resolution and capable of forming a clear recorded image.

In the production of recording paper, polyacrylamide, starch, casein, gum arabic, carboxymethylcellulose, methylcellulose, ordinary PVA, aqueous resin such as sodium polyacrylate, synthetic resin latex such as synthetic rubber latex, dispersed fluorescent dye, pH control material, Various additives such as a foaming agent, a lubricant, a preservative, and a surfactant can be used in combination.

[Operation and Effect] The ink jet recording paper of the present invention has a high ink absorption capacity, a high resolution and gives a clear recorded image.

EXAMPLES Next, the present invention will be described in more detail by way of examples.

Example 1 The content of sodium sulfonate obtained by saponifying a copolymer of sodium allyl sulfonate and vinyl acetate was 5 mol%, and the saponification degree of the vinyl acetate component was 88 mol%.
The following coating solution was prepared using sodium sulfonate-modified PVA having a 5% aqueous solution viscosity (20 ° C.).

Non-colloidal silica powder 100 parts Anionic group-containing PVA resin 50 parts Water 600 parts On the other hand, the sizing degree based on JIS P8122
Using a general high-quality paper (basis weight 65 g / m ² ) of 20 seconds, apply the above coating composition on this base paper with a blade coater to a dry coating amount of 10 g / m ² and dry. Thus, an ink jet recording paper was obtained. Color ink jet recording was performed on this recording paper using the following two color inks, and recording characteristics were evaluated.

 Cyan ink (composition) C.I. Direct Blue 86 2 parts Diethylene glycol 30 parts Water 70 parts Black ink (composition) C.I. Direct Black 19 2 parts Diethylene glycol 30 parts Water 70 parts The evaluation results of the recording paper are shown in Table 1.

However, the dot density was measured for black dots among the dots formed on the surface of the recording material using a Sakura Micro Densidometer PDM-5 (manufactured by Konishi Roku Kogyo Kogyo) by applying JISK7505 to printing microdots. .

The ink absorptivity was evaluated by performing a double-color hitting twice using an IBM3852 color inkjet printer, and when each ink was completely absorbed in the ink receiving layer after 1 second without blurring.

Examples 2 to 4 The same procedure was performed as in Example 1 except that the following modified PVA was used instead of the anion-modified PVA used in Example 1. Table 1 also shows the evaluation results.

Example 2; sodium allyl sulfonate-modified PVA sodium allyl sulfonate: 1 mol% Degree of saponification of vinyl acetate component: 98 mol% 4% aqueous solution viscosity (20 ° C.): 10 cps Example 3: sodium N-sulfoisobutylene acrylamide modified
PVA sodium N-sulfoisobutylene acrylamide: 1
0 mol% Saponification degree of vinyl acetate component: 88 mol% 4% Aqueous solution viscosity (20 ° C.): 20 cps Example 4 Monomethyl maleate-modified PVA monomethyl maleate: 5 mol% Degree of saponification of vinyl acetate component: 90 mol% 4% aqueous solution viscosity (20 ° C): 30 cps Comparative Example 1 Same as Example 1 except that PVA (degree of saponification 98.5, degree of polymerization 1750) was used instead of the anionic group-containing PVA resin used in Example 1. I went to.

 The results are shown in Table 1.

Comparative Example 2 The content of the monomer unit having a cationic group obtained by saponifying a copolymer of vinyl acetate and trimethyl-3- (1-acrylamidopropyl) ammonium chloride was 3 mol%, and the vinyl acetate unit was 98.5 mol% of saponification degree of
The same experiment as in Example 1 was performed, except that the one having a polymerization degree of 1750 was used.

 The results are shown in Table 1.

Claims (2)

(57) [Claims] 1. A 4% aqueous solution in paper and / or a coating layer.
An ink jet recording paper comprising a polyvinyl alcohol resin having an anionic group having a viscosity at 20 ° C. of 2 to 60 cps. 2. The ink jet recording paper according to claim 1, wherein the polyvinyl alcohol-based resin having an anionic group is a polyvinyl alcohol-based resin containing a sulfonate group.