JPH0757553B2 - Inkjet recording sheet with excellent water resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an ink jet recording sheet, and more particularly to an ink jet recording sheet having excellent ink absorbency and remarkably excellent water resistance.

B. Conventional Technology The ink jet recording method is being applied to facsimiles, various printers, etc. because of its low noise, easy colorization, and high-speed recording. Conventionally, ordinary paper has been used as a recording material used in the ink jet recording system. But,
As the performance of the ink jet recording machine is improved by increasing the recording speed or increasing the number of colors, more advanced characteristics are required for the ink jet recording sheet. Ie the first
First, the ink absorption rate is high, secondly, the diameter of the ink dots is not larger than necessary, and thirdly, the water resistance of the ink jet recording sheet itself is high.

In order to meet these requirements, various studies have been made so far, such as using paper or a water-soluble resin as an absorbent for water-soluble inks for ink jet, but increasing the ink absorption speed causes the ink dot diameter to become larger than necessary. At present, it is far from meeting the requirements of a practical level, such as significantly lowering the water resistance.

C. Problems to be Solved by the Present Invention An object of the present invention is to provide an ink jet recording sheet which satisfies the above-mentioned requirements and is particularly excellent in ink absorbency and water resistance.

Still another object of the present invention is that it is used for observation by projecting a recorded image on a screen or the like with an optical device such as a slide or OHP, or has excellent transparency that can be used for transmitted light observation such as color display. Another object is to provide an ink jet recording sheet.

D. Means for Solving the Problems The present inventors have made extensive studies to solve the above problems and achieve the above objects, and as a result, have the following general formula (I) in the supporting substrate and / or the surface. The ink jet recording sheet containing a modified polyvinyl alcohol having a unit (hereinafter, polyvinyl alcohol is abbreviated as PVA) and a water resistant agent is an ink jet recording sheet having excellent ink absorbability and remarkably excellent water resistance. The present invention has been completed and the present invention has been completed.

(Here, R ¹ and R ² represent a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or an alkyl group having 4 or less carbon atoms.) Modified PVA having a unit represented by the general formula (I) used in the present invention. Is a vinyl ester and the following general formula (I
It can be obtained by saponifying a copolymer with the monomer represented by I).

(Here, R ¹ and R ² represent a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or an alkyl group having 4 or less carbon atoms.) Examples of the vinyl ester used in the present invention include vinyl acetate, vinyl propionate, Although vinyl formate can be mentioned, vinyl acetate is preferable from the economical point of view.

In addition, specific examples of the monomer represented by the general formula (II) used in the present invention include N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide and the like. Is mentioned.

When carrying out the copolymerization of the monomer represented by the general formula (II) and the vinyl ester, other copolymerizable monomers other than these, for example, ethylene, propylene, styrene, alkyl Unsaturated acids such as vinyl ether, vinyl versatate, (meth) acrylic acid, maleic anhydride, crotonic acid, itaconic acid, fumaric acid and their alkyl esters, alkali salts, trimethyl-3- (1-
(Meth) acrylamide-1,1-dimethylpropyl) ammonium chloride, trimethyl-3- (1- (meth) acrylamide-1,1-dimethylethyl) ammonium chloride, trimethyl-3- (1- (meth) acrylamidopropyl) A small amount of a monomer having an amino group or an ammonium base such as ammonium chloride, N-vinylimidazole, N-vinyl-N-methylimidazole and quaternary compounds thereof can be used together.

The content of the monomer unit represented by the general formula (II) in the modified PVA used in the present invention is 0.1 to 50 mol%, preferably 0.5 to 20 mol%, more preferably 1 to 1
It is selected from the range of 0 mol%.

The degree of saponification of the vinyl ester unit may be in the water-soluble range, usually 60 to 100 mol%, preferably 70 to 9
It is selected from the range of 5 mol%. Further, the degree of polymerization of the modified PVA is not particularly limited, but usually 50 to 3000, preferably 100 to 2
Selected from the range of 500.

As the water resistant agent used in the present invention, oxalic acid,
Organic acids such as tartaric acid, lactic acid, citric acid, maleic anhydride, itaconic acid, fumaric acid, p-toluenesulfonic acid and sulfamic acid, inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid, or ammonium salts of these acid compounds, chloride Aluminum, aluminum sulfate, magnesium chloride, zinc nitrate and other water-soluble metal hydrochlorides, metal nitrates, metal nitrates, or methylol group-containing compounds such as dimethylol urea, methylol melamine, and methylolated polyamide resin are used, and especially the pH of the aqueous solution. Is preferably near neutral and the viscosity stability of the aqueous solution mixed with the modified PVA is good, and therefore ammonium salts of acids or methylol group-containing compounds are preferably used.

The amount of the waterproofing agent used in the present invention is selected from the range of 0.5 to 50 parts by weight, preferably 1 to 30 parts by weight, based on 100 parts by weight of the modified PVA. The amount of waterproofing agent used
If it is less than 0.5 parts by weight, water resistance tends to be insufficient,
If it exceeds 0 part by weight, the viscosity stability of the aqueous solution tends to be poor, and the ink absorbency tends to be poor.

The modified PVA used in the present invention and the above water-proofing agent may be used alone, or may be used in combination with other water-soluble resin, water-dispersible resin, inorganic filler or the like.

Other water-soluble or water-dispersible resins that can be used in combination include albumin, gelatin, casein, starch, gum arabic, methyl cellulose, cellulose derivatives such as hydroxyethyl cellulose, polyamide resin, melamine resin, PVA, vinylpyrrolidone-modified PVA, N- Substituted or non-substituted (meth) acrylamide modified PVA, poly (meth) acrylamide, nonionic water-soluble resin such as polyvinylpyrrolidone, CMC, sodium poly (meth) acrylate, anion-modified PVA, anion such as sodium alginate, water-soluble polyester Water-soluble resin, polyethyleneimine, polyvinylamine, polyallylamine, polyallylamine sulfone copolymer or their ammonium salts, cationized starch, cationized poly (meth)
Cationic water-soluble resin such as acrylamide, cation-modified PVA, cationized polyamide resin, SBR latex, N
BR latex, vinyl acetate emulsion, ethylene /
Examples of the water-dispersible resin include vinyl acetate copolymer emulsion, (meth) acrylic ester emulsion, vinyl chloride emulsion and the like. Among them, modified or unmodified PVA is preferable, and cation-modified PVA is particularly preferable.

When these water-soluble or water-dispersible resins are used in combination with the modified PVA and the waterproofing agent used in the present invention, the combined ratio is 500 parts by weight or less, preferably 100 parts by weight of the modified PVA of the present invention, Is used up to 300 parts by weight.

Further, as the inorganic filler that can be used in combination in the present invention, silica, clay, talc, diatomaceous earth, zeolite,
Examples include calcium carbonate, alumina, suboxide, and satin white. The combined ratio in this case is different between the recording sheet having excellent transparency and the other cases, but usually [modified PVA / filler used in the present invention] is 1/10 to 100
/ 1, preferably 5/10 to 100/5.

The composition composed of the modified PVA and the water-proofing agent used in the present invention can be used as the ink absorbing layer because it has excellent ink absorbability by itself, but the composition of the ink absorbing layer made of another ink absorbing material It is also possible to form a layer of the composition on the surface and use it as a water resistant layer.

As the supporting substrate used in the present invention, any conventionally known supporting substrate having transparency and opacity can be used. Examples of the transparent supporting substrate include polyester, polystyrene, polyvinyl chloride, polymethylmethacrylate, cellulose acetate, polycarbonate, polyimide, cellophane,
Films such as celluloid, sheets, highly transparent paper, etc. may be mentioned. Examples of the opaque support substrate include general paper, pigment-coated paper, cloth, wood, metal plate, synthetic paper, opaque synthetic resin film or sheet, and the like.

In the case of an ink jet recording sheet having excellent transparency which is one of the objects of the present invention, a transparent supporting substrate is used.

In the present invention, the method for incorporating the composition comprising the above-mentioned modified PVA and the water-proofing agent into the supporting substrate and / or the surface is as an aqueous solution of the above-mentioned composition or other water-soluble or water-dispersible resin or filler. A mixture aqueous solution or water dispersion with a material is impregnated into a supporting substrate by an ordinary coating method such as a size press, an air knife coater, a roll coater, a bar coater, or a blade coater, or an upper surface or an upper surface of the supporting substrate. A method of forming a coat layer on both the lower surface and the lower surface can be used.

When the supporting substrate is paper, a method of internally adding the above-mentioned aqueous solution or aqueous dispersion during papermaking can also be used.

After impregnating or coating by the method as described above, it is then dried. The drying temperature at this time is selected from the range of 60 ° C to 180 ° C, preferably 80 ° C to 150 ° C, and more preferably 100 ° C to 130 ° C. If the drying temperature is lower than 60 ° C, the water resistance is difficult to develop, and if the drying temperature is higher than 180 ° C, the ink absorbency tends to decrease.

The content of the aforementioned composition in the ink jet recording sheet of the present invention is not particularly limited, but is usually 0.1 to 200 g / m ^2.
Preferably 0 to 100 g / m ² is used.

E. Action and Effect of the Invention The ink jet recording sheet of the present invention has excellent ink absorbency and remarkably excellent water resistance. The reason why the ink jet recording sheet having the above-described excellent performance can be obtained is not fully understood, but it is presumed as follows.

That is, it is presumed that the modified PVA used in the present invention forms a hydrophilic and water-insoluble film by forming a hydrophilic and water-insoluble film by heating and drying in the presence of the above-mentioned waterproofing agent to form a cross-linkage bond with a hydroxyl group.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The present invention is not limited thereby. In the examples, "%" and "parts" are based on weight unless otherwise specified.

The methods for measuring various physical properties in the examples are shown below.

(1) Ink Jet Recording Method Using a recording apparatus having an on-demand type ink jet recording head having an ejection orifice diameter of 60 μm, color ink jet recording was performed using the following four colors of ink, and the recording characteristics were evaluated.

Yellow ink (composition) CI Acid Yellow 2.3 2 parts Diethylene glycol 30 parts Water 70 parts Magenta ink (composition) CI Acid Red 32 2 parts Diethylene glycol 30 parts Water 70 parts Cyan ink (composition) CI Direct Blue 86 2 parts Diethylene glycol 30 parts Water 70 Part Black ink (composition) CI Direct black 19 2 parts Diethylene glycol 30 parts Water 70 parts (2) Ink absorption speed Time until the printed part does not change after rubbing the print on the recording sheet with a finger after every fixed time after ink jet recording. Was measured. The shorter the time, the faster the ink absorption rate.

(3) Degree of bleeding The diameter of the printed dots was measured with a stereoscopic microscope to show how many times the number of ink droplets increased. A lower magnification indicates less bleeding.

(4) Transparency The visible light transmittance (%) of the non-printed portion of the ink jet recording sheet was measured with a spectrophotometer using visible light having a wavelength of 500 nm. This transparency is used as the transparency. The higher the transmittance, the higher the transparency.

(5) Water resistance It was judged whether or not the printed portion of the sheet after ink jet recording was soaked with water and rubbed with a finger, the printed portion was dissolved or smeared. 5: No change ~ 1: Bleeding and dissolution.

Example 1 A polyester sheet having a thickness of 50 μm and a transparency of 95% contains 5 mol% of an acrylamide unit obtained by saponifying a copolymer of vinyl acetate and N-butoxymethylacrylamide, and a saponification degree of the vinyl acetate unit. 88 mol%, degree of polymerization
10 including 1800 modified PVA 100 parts and ammonium chloride 10 parts
% Solution so that the applied amount after drying is 15 g / m ^2.
It was dried at 0 ° C. for 2 minutes to obtain an ink jet recording sheet. Ink absorption rate, bleeding degree, transparency,
The water resistance is shown in Table 1.

Comparative Examples 1 to 3 The procedure of Example 1 was repeated, except that the following resin was used instead of the composition used in Example 1. The results are also shown in Table 1.

Resin used in Comparative Example 1: Modified PVA used in Example 1
only.

Resin used in Comparative Example 2: polyvinylpyrrolidone.

Resin used in Comparative Example 3: a cation-modified PVA containing 2 mol% of cationic groups, having a degree of polymerization of 1750 and a degree of saponification of 88 mol%.

Example 2 The procedure of Example 1 was repeated except that the composition used in Example 1 was replaced with a mixture of 100 parts of the composition and 200 parts of the cation-modified PVA used in Comparative Example 3. The results are also shown in Table 1.

Example 3 Art paper was used as a supporting substrate, and 1 mol% of acrylamide units obtained by saponifying a copolymer of vinyl acetate and N-methoxymethylacrylamide were contained on the surface of the art paper. Is 85 mol%, degree of polymerization is 15
A 10% aqueous solution consisting of 100 parts of modified PVA of 00 and 20 parts of methylolated polyamide resin was applied so that the coating amount after drying was 20 g / m ^2, and dried at 130 ° C. for 1 minute to obtain an ink jet recording sheet. . The performance of this sheet is also shown in Table 1.

Example 4 In place of the composition used in Example 3, 100 parts of the composition and 10 mol% of vinylpyrrolidone units were contained, and the saponification degree was
The same procedure as in Example 3 was carried out except that a mixture of 80 mol% and 100 parts of modified PVA having a polymerization degree of 1000 was used. The results are also shown in Table 1.

Comparative Examples 4 to 5 The procedure of Example 3 was repeated, except that the following resin was used instead of the composition used in Example 3. The results are also shown in Table 1.

Resin used in Comparative Example 4: saponification degree 88 mol%, polymerization degree 1750
100 parts of PVA and 20 parts of the methylolated polyamide resin used in Example 3.

Resin used in Comparative Example 5: Only the methylolated polyamide resin used in Example 3 was used.

Example 5 Using a high quality paper as a supporting substrate, a coating solution having the following composition using the composition used in Example 3 was applied by a bar coater to a dry solid content of 20 g / m ^2, and the temperature was increased to 130 ° C. It was dried for 30 seconds to obtain a recording sheet. The ink absorption rate, the degree of bleeding, and the water resistance of this sheet are shown in Table 2.

Comparative Example 6 The procedure of Example 5 was repeated, except that the composition used in Comparative Example 4 was used instead of the composition used in Example 5. The results are also shown in Table 2.

Example 6 Using high-quality paper as a supporting substrate, the mixture used in Example 2 was applied so as to have a dry solid content of 5 g / m ² and dried to obtain a recording sheet. The performance of this sheet is shown in Table 3.

Comparative Example 7 Example 6 was repeated except that polyvinyl pyrrolidone was used instead of the mixture used in Example 6. The results are also shown in Table 3.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Junnosuke Yamauchi 1621 Sakata, Kurashiki City, Okayama Prefecture Kuraray Co., Ltd. (56) References JP-A-61-134291 (JP, A)

Claims (2)

[Claims] 1. A sheet for ink jet recording excellent in water resistance, which comprises a modified polyvinyl alcohol having a unit represented by the following general formula (I) in a supporting substrate and / or on the surface thereof and a waterproofing agent. . (Here, R ¹ and R ² represent a hydrogen atom or a methyl group, and R ³ represents a hydrogen atom or an alkyl group having 4 or less carbon atoms.) 2. The ink jet recording sheet according to claim 1, wherein the weight blending ratio of the modified polyvinyl alcohol and the waterproofing agent is 100 / 0.5 to 100/50.