JPH0832478B2 - Recording medium for ink - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an ink recording medium, and particularly to an ink recording having excellent absorbability of a water-based ink for ink jet recording or a water-based ink for pen plotter, and also having extremely excellent water resistance. Regarding the medium.

B. Conventional technology In recent years, the ink jet recording method is being applied to various printers and printers because of its low noise, easy colorization, and high-speed recording. . Also, for pen plotters, a method of using water-based ink is becoming popular because the pen tip is hard to dry and is easy to use, and recording can be performed smoothly.

Conventionally, ordinary paper has been used as a recording material used in these recording methods. However, with the improvement of the performance of the recording machine such as high-speed recording or multicolor recording, more advanced characteristics are required for the ink recording medium.
That is, first, the ink absorption speed is high, secondly, the ink does not bleed, for example, when used as an ink jet recording medium, the diameter of the ink dot does not become larger than necessary, and thirdly, the ink recording medium. It has high water resistance.

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 ink, but if the ink absorption speed is increased, remarkable bleeding may occur (for example, for ink jet recording). When used as a medium, the ink dot diameter becomes larger than necessary), the water resistance becomes significantly low, etc.
The current situation is that it does not fall far short of practical requirements.

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

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

D. Means for Solving the Problems The inventors of the present invention have solved the above-mentioned problems and have conducted diligent studies to achieve the above-mentioned objects. As a result, a polyvinyl alcohol-based resin (hereinafter, polyvinyl alcohol is abbreviated as PVA is referred to as a supporting substrate). ), A recording medium for ink containing chitosan and an aldehyde compound, especially on the surface of a supporting substrate, PV.
The present invention finds that an ink recording medium having an ink absorbing layer containing an A-based resin, chitosan and an aldehyde compound is an ink recording medium having excellent ink absorbability and extremely excellent water resistance, and completes the present invention. It has come to.

 The present invention will be described in more detail below.

The PVA-based resin used in the present invention may be any water-soluble resin, and in addition to ordinary PVA, silane-modified P
Anion-modified PVA such as VA, carboxyl group-modified PVA, sulfonic acid group-modified PVA, phosphoric acid group-modified PVA or cation-modified PVA
PVA or ethylene, vinyl ether having a long chain alkyl group, vinyl ester, (meth) acrylamide,
Modified PVA or the like obtained by copolymerizing alfa olefin or the like can also be used.

The degree of polymerization of these PVA-based resins is not particularly limited, but is usually selected from the range of 100 to 3000, and the degree of saponification is not particularly limited as long as it is in the water-soluble range, but is usually 70 to 100.
It is selected from the range of mol%.

The chitosan used in the present invention has an amino group of 40
% Or more, preferably 80% or more, or those in which some or all of these amino groups are converted to ammonium groups by an acid are used.

The molecular weight of the chitosan is not particularly limited and various ones can be used, but the viscosity of a 1% aqueous solution at 20 ° C. (by a BL type viscometer: hereinafter the same) is 70 centipoise (hereinafter centipoise is abbreviated as cp). Those having a molecular weight of more than 1 have a high viscosity of the coating liquid composed of the PVA-based resin and chitosan and the aldehyde-based compound used in the present invention, and are compatible with the PVA-based resin when the concentration of the coating liquid is high. In some cases, the water resistance effect may not be sufficiently exhibited, and therefore the viscosity of the 1% aqueous solution is preferably 1 to 70 cp, and more preferably 1 to 30 cp.

The chitosan used in the present invention can be dissolved in water or an aqueous solution containing an acid. The acid is usually acetic acid,
Formic acid, lactic acid, citric acid, benzoic acid, sulfamic acid, hydrochloric acid, sulfuric acid, phosphoric acid, fumaric acid, maleic acid and the like are used.

As the aldehyde compound used in the present invention, any compound that is water-soluble and generates an aldehyde in an aqueous solution may be used, and specifically, for example, formalin, acetaldehyde, propionaldehyde, monoaldehyde such as butyraldehyde, glyoxal, Glutaraldehyde,
Polyaldehyde such as dialdehyde starch, condensate of formalin and ammonia such as hexamethylenetetramine,
Examples thereof include dimethylol urea, methylol amide such as N-methylol acrylamide, urea formalin resin, melamine formalin resin and the like.

Among the above-mentioned aldehyde compounds, glyoxal or hexamethylene is used from the viewpoint of ease of use of the coating solution composed of the PVA resin used in the present invention and chitosan and the aldehyde compound (odorless, viscosity stability, etc.) and water resistance. Tetramine is preferably used.

Further, the weight blending ratio of the PVA-based resin and the chitosan and the aldehyde-based compound is such that the chitosan is 1 to 50 parts, preferably 5 to 30 parts, and the aldehyde-based compound is 0.1 to 10 parts, preferably 100 to 10 parts of the PVA-based resin. 0.5-5 parts is preferred. If the amount of chitosan is less than 1 part, there is no effect, and if it exceeds 50 parts, the viscosity of the above-mentioned coating solution increases, which is not preferable. If the amount of the aldehyde compound is less than 0.1 part, no effect is obtained, and if it exceeds 10 parts, the viscosity stability of the above-mentioned coating solution is deteriorated.

The composition comprising the PVA resin, chitosan and aldehyde compound used in the present invention can be used alone or in combination with other water-soluble or water-dispersible resin.

Other water-soluble or water-dispersible resins that can be used in combination include albumin, gelatin, casein, starch, gum arabic, cellulose derivatives such as methyl cellulose and hydroxyethyl cellulose, polyamide resin, melamine resin, poly (meth) acrylamide, polyvinylpyrrolidone, etc. Nonionic water-soluble resin, CMC, poly (meth)
Anionic water-soluble resins such as sodium acrylate, sodium alginate, water-soluble polyester, polyethyleneimine, polyvinylamine, polyallylamine, polyallylaminesulfone copolymers or their ammonium salts, cationized starch, cationized poly (meth) ) Acrylamide, cationic water-soluble resin such as cationized polyamide resin, water such as SBR latex, NBR latex, vinyl acetate emulsion, ethylene / vinyl acetate copolymer emulsion, (meth) acrylic ester emulsion, vinyl chloride emulsion A dispersible resin can be used.

The combination ratio of these water-soluble or water-dispersible resins used in combination with the composition used in the present invention is 100 parts by weight or less, preferably 50 parts by weight, relative to 100 parts by weight of the PVA-based resin of the present invention. Used in parts by weight or less.

Further, the PVA-based resin used in the present invention, a composition composed of chitosan and an aldehyde-based compound is used in combination with a filler such as silica, clay, talc, diatomaceous earth, xeraoite, calcium carbonate, alumina, zinc oxide, and satin white. It can also be used. In this case, the combination ratio differs between the recording medium having excellent transparency and the other cases, but the PVA resin / filler of the present invention is usually used in a weight ratio of 1: 1.
It is selected from the range of 100 to 100/1, preferably 5/100 to 100/5.

The PVA-based resin used in the present invention, a composition composed of chitosan and an aldehyde-based compound, which itself can be used as an ink absorbing layer because of its excellent ink absorbency, can be used as an ink absorbing material made of another ink absorbing material. A layer made of the composition may be formed on the layer and used as a water resistant layer.

As the support substrate used in the present invention, any of conventionally known support substrates having transparency and opacity can be used. Examples of the transparent support substrate include films such as polyester, polystyrene, polyvinyl chloride, polymethylmethacrylate, cellulose acetate, polycarbonate, polyimide, cellophane and celluloid, and sheets or highly transparent paper. 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 recording medium having excellent transparency, which is one of the objects of the present invention, a transparent supporting substrate is used.

In the present invention, as a method of incorporating a composition comprising a PVA-based resin, chitosan and an aldehyde-based compound into a supporting substrate, an aqueous solution of the above-mentioned composition or a mixed aqueous solution of the same with another water-soluble or water-dispersible resin or filler is used. Alternatively, the supporting substrate is impregnated with the aqueous dispersion by a conventional coating method such as a size press, an air knife coater, a roll coater, a bar coater, or a blade coater, or both the upper surface and the upper and lower surfaces of the supporting substrate are impregnated. A method such as forming a coat layer on the surface can be used.

It is also possible to coat the supporting substrate with an adhesive resin and then coat the composition described above thereon. Examples of the adhesive resin used in this case include a composition of polyurethane and isocyanate, a rubber-based adhesive, an emulsion-based adhesive, and the like.

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.

The content of the composition comprising the PVA-based resin, chitosan and aldehyde-based compound in the recording medium for an ink of the present invention is not particularly limited, but is usually 0.1 to 200 g / m ² , preferably 1 to 100 g / m 2. ² is used.

The recording medium for ink of the present invention is useful as a medium for ink jet recording to record mainly by spraying a liquid ink, particularly an aqueous ink, but is not limited to this.
It is similarly useful as a recording medium for a pen plotter or a recording pen for recording by directly contacting a liquid ink, particularly an aqueous ink, with the recording medium.

E. Action and Effect of the Invention The reason why the ink recording medium of the present invention has excellent ink absorbability and remarkably excellent water resistance is not fully understood, but it is presumed as follows.

The PVA-based resin used in the present invention, a composition consisting of chitosan and an aldehyde-based compound is water-soluble before film formation and hydrophilic even after film formation, but the resulting film is remarkably high in water resistance. It is presumed that it is possible to form a recording medium for ink that is extremely excellent in water resistance as well as absorbency.

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

 In addition, the measuring method of various physical properties in an Example is 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 color inks to evaluate the recording characteristics.

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 rate After recording with ink, rub the print on the recording sheet with a finger at regular intervals until the print part does not change. Was measured. The shorter the time, the faster the ink absorption rate.

(3) Degree of bleeding The diameter of the printed dots was measured by a stereoscopic microscope to show how many times the number of ink droplets dropped on the ink jet. The lower the magnification, the less bleeding.

(4) Transparency The visible light transmittance (%) of the non-printed portion of the ink recording medium was measured with a spectrophotometer using visible light having a wavelength of 500 nm. This transmittance is defined as 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 recording was soaked with ink and rubbed with a finger to dissolve or bleed the printed portion.

5: No change.

4: Slight bleeding but no dissolution.

3: Bleeding, no dissolution but swelling.

2: There is bleeding and it dissolves a little.

1: Bleed and dissolve.

Example 1 PVA (Kuraray Bopearl) having a degree of polymerization of 550 and a degree of saponification of 80 mol%
PVA-405) 100 parts and 15% chitosan having a viscosity (viscosity measured by a BL type viscometer) at 20 ° C. of a 1% aqueous solution of 13 cp and an amino group content of 89% were dissolved in an acidic acetic acid aqueous solution to prepare a 15% aqueous solution. Was prepared.

40% glyoxal is added to this aqueous solution as PVA in terms of solid content.
To 2% to prepare a coating liquid.

This coating liquid was applied onto a polyester sheet having a thickness of 50 μm and a transparency of 95% so that the coating amount after drying was 20 g / m ^2, and dried to obtain a recording medium for ink. Table 1 shows the ink absorption rate, bleeding degree, transparency and water resistance when ink jet recording was performed on this sheet.

Examples 2 to 8 PVA-based resin or chitosan content of Example 1
The same procedure as in Example 1 was carried out except that the changes were made as shown in the table.
The results are shown in Table 1.

Comparative Examples 1 to 4 The procedure of Example 1 was repeated, except that the following resin was used instead of the composition used in Example 1. Combined results 1st
Shown in the table.

Resin used in Comparative Example 1: 15% aqueous solution consisting of 100 parts of PVA-405 and 2 parts of glyoxal.

Resin used in Comparative Example 2: 10% aqueous solution containing only chitosan used in Example 1.

Resin used in Comparative Example 3: 10% aqueous solution containing only polyvinylpyrrolidone.

Resin used in Comparative Example 4: containing 2 mol% of cationic group, polymerization degree 1750, saponification degree 88
A 15% aqueous solution consisting only of mol% cation-modified PVA.

Examples 9 to 12 Table 2 shows the viscosities of 100 parts of modified PVA having a polymerization degree of 1750 and a saponification degree of 80 mol% and a 1% aqueous solution (viscosity measured by a BL type viscometer) containing 2 mol% of cationic group units. 10 parts of chitosan having the value shown and an amino group content of 85% was dissolved in an acidic aqueous solution of lactic acid to prepare a 15% aqueous solution. To this aqueous solution, 40% glyoxal was added at a ratio of 1% with respect to PVA in terms of solid content to prepare a coating liquid.

This coating solution was applied onto a transparent polyester film sheet having a thickness of 75 μm so that the coating amount after drying was 5 g / m ^2, and dried to obtain a recording medium for ink. Table 2 also shows the ink absorption speed and water resistance when recording was performed on the sheet with an ink jet.

Examples 13 to 15 The procedure of Example 9 was repeated, except that the addition amount of glyoxal used in Example 9 was changed as shown in Table 2. The results are also shown in Table 2.

Examples 16 to 20 Glyoxal used in Example 9 (1% / PV
Example 9 was carried out in the same manner as in Example 9 except that the aldehyde compound shown in Table 2 and the addition amount were used instead of A). The results are also shown in Table 2.

Example 21 Recording for ink by applying the composition used in Example 8 on the polyvinylpyrrolidone layer of the recording medium for ink obtained in Comparative Example 3 so as to have a dry solid content of 5 g / m ² and drying. The medium was obtained. The results are shown in Table 3.

Example 22 Cation modification of recording medium for ink obtained in Comparative Example 4
The composition used in Example 1 was applied to a layer of PVA with a dry solids content of 3
A recording medium for ink was obtained by coating so as to be g / m ² and drying. The results are also shown in Table 3.

Example 23 Example 23 was repeated except that art paper was used as the supporting substrate. The ink absorption speed is 25 seconds, and the degree of bleeding is
The water resistance was 2.1 times and the water resistance was 5.

Example 24 Using fine paper as a supporting substrate, a coating solution having the following composition using the composition used in Example 1 was applied by a bar coater to a dry solid content of 20 g / m ² and dried to obtain an ink. A recording medium for use was obtained. Ink absorption rate, bleeding degree, and water resistance of this sheet are shown in Table 4.

Comparative Example 5 Example 24 was repeated except that the composition used in Example 24 was replaced with the PVA used in Comparative Example 1. The results are also shown in Table 4.

Example 25 Using high-quality paper as a supporting substrate, the composition used in Example 2 was applied to a dry solid content of 5 g / m ² and dried to obtain an ink recording medium. The performance of this sheet is shown in Table 5.

Comparative Example 6 The procedure of Example 25 was repeated except that polyvinyl pyrrolidone was used instead of the composition used in Example 25.
The results are also shown in Table 5.

Example 26 Using the recording medium obtained in Example 9, a pen having one of each of the four colors of ink used in the ink jet was used to draw straight lines and overlapping solid fill circles with a pen plotter.

Immediately after recording with the pen, the printed portion did not change even if the recorded portion was rubbed with a finger. In addition, it was possible to record the orthogonal portions and overlapping filled circles without bleeding of the inks from each other and without blurring of the coat layer.

 The water resistance after the recording was 5.

Comparative Examples 7 to 8 The procedure of Example 26 was repeated except that the following recording media were used. The results are as follows.

Recording medium used in Comparative Example 7: the one obtained in Comparative Example 1.

Ink bleeding was severe at the orthogonal portion and the overlapping circle portion, and the water resistance was 1.

Recording medium used in Comparative Example 8: the one obtained in Comparative Example 3.

At the orthogonal part and the part of the overlapping circles, the blurring of the pen caused by scratching of the pen and the bleeding of the ink became intense. The water resistance was 1.

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Claims (11)

[Claims] 1. A supporting substrate is a polyvinyl alcohol-based resin,
A recording medium for ink having excellent water resistance, which comprises chitosan and an aldehyde compound. 2. A recording medium for ink having excellent water resistance according to claim 1, further comprising an ink absorbing layer containing a polyvinyl alcohol resin, chitosan and an aldehyde compound on the surface of the supporting substrate. 3. The blending ratio of polyvinyl alcohol resin, chitosan and aldehyde compound is 1 to 50 parts by weight of chitosan and 0.1 to 10 parts by weight of aldehyde compound to 100 parts by weight of polyvinyl alcohol resin. An ink recording medium having excellent water resistance according to claim 1. 4. The recording medium for ink having excellent water resistance according to claim 1, wherein chitosan has a viscosity of a 1% aqueous solution at 20 ° C. of 1 to 70 centipoise. 5. The recording medium for ink having excellent water resistance according to claim 4, wherein chitosan has a viscosity of 1 to 30 centipoise as a 1% aqueous solution at 20 ° C. 6. The aldehyde compound is one or more selected from the group consisting of water-soluble monoaldehydes, polyhydric aldehydes, condensates of amines and formalin, methylolamide, urea formalin resins or melamine formalin resins. A recording medium for ink having excellent water resistance according to claim 1, which is a compound of 7. The method according to claim 6, wherein the aldehyde compound is glyoxal or hexamethylenetetramine.
A recording medium for ink having excellent water resistance according to the item. 8. The recording medium for ink having excellent water resistance according to claim 1, wherein the supporting substrate is a transparent film or sheet. 9. The recording medium for ink having excellent water resistance according to claim 1, wherein the supporting substrate is paper. 10. The recording medium for ink according to claim 1, wherein the recording medium for ink is a recording medium for ink jet recording. 11. The ink recording medium according to claim 1, wherein the ink recording medium is a pen plotter recording medium using a water-based ink.