JPS63176174A - Inkjet recording sheet with excellent water resistance - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording sheet, and more particularly to an inkjet recording sheet that has excellent ink absorbency and extremely excellent water resistance.

B. Conventional technology The inkjet recording method is being applied to facsimiles, various printers, etc. because of its low noise, ease of colorization, and high-speed recording. Conventionally, ordinary paper has been used as a recording material used in inkjet recording methods. but,
BACKGROUND ART As the performance of inkjet recording machines improves, such as faster recording and multicolor recording, more advanced properties are required of inkjet recording sheets. That is, the first
The first is that the ink absorption speed is high, the second is that the diameter of the ink dots does not become larger than necessary, and the third is that the inkjet recording sheet itself has high water resistance.

In order to meet these demands, various studies have been made in the past, such as using paper or water-soluble resin as an absorbing material for aqueous inkjet ink, but increasing the ink absorption speed resulted in an unnecessarily large ink dot diameter. The current situation is that it is far from meeting the requirements for practical use, such as significantly lower water resistance.

C0 Problems to be Solved by the Present Invention An object of the present invention is to provide an inkjet recording sheet that satisfies the above requirements and is particularly excellent in ink absorbency and water resistance.

Yet another object of the present invention is to use an optical device such as a slide or an OHP to project a recorded image onto a screen for observation, or to use it for observation of transmitted light such as a color display. An object of the present invention is to provide an inkjet recording sheet with excellent transparency.

The present inventors solved the above-mentioned problems and made extensive studies to achieve the above-mentioned objectives.
An inkjet recording sheet containing a waterproofing agent (abbreviated as VA) and a waterproofing agent containing two or more epoxy groups or ethyleneimine groups in the molecule has excellent ink absorption properties,
The present inventors discovered that the inkjet recording sheet had excellent water resistance and completed the present invention.

The carboxyl-modified PVA used in the present invention can be obtained by saponifying a copolymer of a vinyl ester and a carboxyl group-containing olefinic unsaturated monomer.

Vinyl esters used in the present invention include vinyl acetate, vinyl propionate, and vinyl formate, but vinyl acetate is preferred from an economical standpoint.

In addition, examples of the carboxyl group-containing olefinically unsaturated monomer used in this method include: leic acid,
Dicarboxylic acids such as fumaric acid and itaconic acid, their anhydrides, salts and alkyl esters thereof, monocarboxylic acids such as (meth)acrylic acid, salts thereof and alkyl esters thereof, but dicarboxylic acids Preferable 0 When carrying out the above-mentioned copolymerization, in addition to these, other copolymerizable monomers such as ethylene, propylene, styrene, alkyl vinyl ether, vinyl versatate, (meth)acrylamide, trimethyl-3 -(1-(
meth)acrylamido-1,1-dimethylpropyl)ammonium chloride, trimethyl-3-(1-(meth)acrylami)'-1,1-dimethylethyl)ammonium chloride, trimethyl-3-(1-(meth)acrylamide propyl) ammonium chloride, N-
A small amount of a monomer having an amide group or an ammonium group such as vinylimidazole, N-vinyl-N-methylimidazole, and quaternized products thereof can also be used in combination.

The content of carboxyl groups in the modified PVA used in the present invention is selected from the range of 0.1 to 10 moles, preferably 0.5 to 5 moles, as carboxyl group-containing olefinically unsaturated monomer units. The degree of saponification of the vinyl ester unit may be within a water-soluble range, and although it varies depending on the content of the monomer unit having a carboxyl group, it is usually 50 to 100 mol, preferably 70 to 100 mol.
Selected from the range of 95 molti. Further, the degree of polymerization of the modified PVA is not particularly limited, but is usually selected from the range of 50 to 3,000, preferably 100 to 2,500.

In addition, carboxyl-modified PV used in the present invention
As A, a modified PVA having a carboxyl group and a craft or block copolymer of (meth)acrylamide, (meth)acrylonitrile, (meth)acrylic acid ester, etc. can also be used.

Examples of the water-resistant agent containing two or more epoxy groups or ethyleneimine groups in the molecule used in the present invention include ethylene oxide, propylene oxide, trimethylolpropane, glycerin, or a reaction product of a condensate thereof and epichlorohydrin; A reaction product of a polyamide resin obtained by condensation of an alkyl polyamine compound and an alkyl dicarboxylic acid and epichlorohydrin,
Examples include reaction products of hexamethylene diisocyanate or methylene bisdiphenyl diisocyanate and ethyleneimine.

The blending ratio of the above-mentioned modified PVA and the water resistant agent used in the present invention is 10015 to 1.00150 by weight,
It is preferably selected from the range of IQO/10 to 100/40.

The modified PVA and water-resistant agent used in the present invention can be used alone or in combination with other water-soluble or water-dispersible resins.

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, ordinary unmodified PVA, and polyamide resin. 7-ionic water-soluble resins such as (meth)acrylamide and polyvinylpyrrolidone,
CMC, sodium poly(meth)acrylate, sodium alginate, anionic water-soluble resin such as water-soluble polyester, polyethyleneimine, polyvinylamine, polyallylamine, polyallylamine sulfone copolymer or ammonium salt thereof, cationized starch, Cationized poly(meth)acrylamide, cation-modified PV
A, cationic water-soluble resin such as cationized polyamide resin, SBR latex, NBR latex, acid 0-rabinyl emulsion, ethylene/vinyl acetate copolymer emulsion resin, (meth)acrylic ester emulsion,
Examples include water-dispersible resins such as vinyl chloride emulsions.

These water-soluble or water-dispersible 1'! When li1 fat is used in combination with the modified PVA and waterproofing agent used in the present invention, the proportion of the combined use is as follows:
V A 100 Mn is used in an amount of less than 100 parts by weight, preferably less than 50 parts by weight.

Furthermore, the modified PVA and waterproofing agent used in the present invention can also be used in combination with fillers such as silica, clay, talc, diatomaceous earth, zeolite, calcium carbonate, alumina, zinc oxide, and satin white. . In this case, the proportion of the combined use differs depending on the recording sheet with excellent transparency and other cases, but usually the modified PV of the present invention
A/The filler is selected from the range of 1/100 to 100/1, preferably 5/100 to 10015 in terms of weight ratio. It can also be used as an ink absorbing layer because of its excellent properties, but it can also be used as a water-resistant layer by forming a layer called υ on an ink absorbing layer made of another ink absorbing material. You can also do that.

The supporting substrate used in the present invention is transparent.

Any conventionally known opaque support substrate can be used.

Transparent support substrates include, for example, polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate,
Examples include films and sheets of cellulose acetate, polycarbonate, polyimide, hexachloride, celluloid, and highly transparent paper. Examples of the opaque support substrate include ordinary paper, pigment-coated paper, cloth, wood, metal plates, synthetic paper, and synthetic resin films or sheets that have been opaquely treated.

In the case of an inkjet recording sheet that has excellent transparency, which is one of the objects of the present invention, a transparent support substrate is used.

In the present invention, the method of incorporating a mixture of modified PVA and a water resistant agent into the supporting substrate includes an aqueous solution of the above-mentioned mixture of modified PVA and a water resistant agent, or a mixture of this and other water-soluble or water-dispersible resins, or The aqueous solution or aqueous dispersion of the mixture with the filler is processed using a size press, air knife coater,
The coating layer may be impregnated into the support substrate using a conventional coating method such as a roll coater, bar coater, or plate coater, or a coating layer may be formed on the upper surface or both the upper and lower surfaces of the support substrate. method can be used.

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

The above-mentioned modified P in the inkjet recording sheet of the present invention
There is no particular restriction on the content of the composition consisting of VA and a water resistant agent, but it is usually 0.1 to 2001 P/rr! Preferably 1 to 100r/rr? is used.

86 Actions and Effects of the Invention The reason why the inkjet recording sheet of the present invention has excellent ink absorbency and extremely excellent water resistance is not fully elucidated, but is presumed to be as follows.

The carboxyl-modified PVA used in the present invention and the water-resistant agent containing two or more epoxy groups or ethyleneimine groups in the molecule are water-soluble before film formation, and after film formation are hydrophilic. However, since the obtained film has extremely high water resistance, it is presumed that an inkjet recording sheet having extremely excellent ink absorbency and water resistance can be formed.

The present invention will be explained in more detail with reference to Examples below.
The present invention is not limited thereby. In the examples, unless otherwise specified, "width 6; and r section" represent the electrolytic corrosion standard.

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

(1) Inkjet Recording Method 5 Using a recording apparatus having an on-demand inkjet recording head with an ejection orifice diameter of Q prn, color inkjet recording was performed using the following four color inks, and the recording characteristics were evaluated.

Yellow ink (composition) C, I acid yellow 2.3 2 parts diethylene glycol 30 parts water
70 parts Magenta ink (composition) C, I, Acid Red 32 2 parts diethylene glycol 30 parts water
70 parts Cyan ink (composition) C, 1, 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
After inkjet recording of 70 copies, the print on the recording sheet was rubbed with a finger at regular intervals, and the time until the print area stopped changing was measured. The shorter the time, the faster the ink absorption speed.

(Al Bleeding degree) The diameter of the printed dot was measured using a stereomicroscope, and the diameter was shown as how many times larger than the ink droplet.The lower the magnification, the less the bleeding.

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

(5) Water resistance When the printed area of the sheet after inkjet recording was soaked in water and rubbed with a finger, judgment was made based on whether the printed area dissolved or smeared. 5: No change to 1: Bleeding and dissolution.

Example 1 A polyester sheet with a thickness of 50 μm and a transparency of 95% contains t-1 mol of carboxyl group units obtained by saponifying a copolymer of vinyl acetate and itaconic acid, and the saponification degree of vinyl acetate units is 88. A 10% aqueous solution of cP containing 100 parts of modified PVt with a degree of polymerization of 1750 and 30 parts of a reaction product of a polyamide resin and epichlorohydrin was applied so that the coating amount after drying was 15 f/♂, dried, and in-jet recording was performed. Ink absorption speed, K bleed, transparency, and water resistance of the sheet are shown in Table 1.Example 2 Instead of the water resistance agent used in Example 1, methylene bisdiphenyl diisocyanate and ethyleneimine were used. Example 1 was carried out in the same manner as in Example 1 except that the reaction product with was used. Results first
0 Comparative Example 1 shown in the table as well. ~5 The results were also shown in Table 1 in the same manner as in Example 1, except that the following resin was used in place of the blend of modified PVA and waterproofing agent used in Example 1.

Resin used in Comparative Example 1: degree of polymerization 1750, degree of saponification 98
．． Only 5 molti PVA.

Resin used in Comparative Example 2: Only the modified PVA used in Example 1.

Resin used in Comparative Example 3: Only the water resistant agent used in Example 1.

Resin used in Comparative Example 4: polyvinylpyrrolidone.

Resin used in Comparative Example 5: Contains 2 moles of cationic group fe, polymerization degree 1750. Only cationically modified PVA with a saponification degree of 88 mol.

Example 3 The formulation used in Example 1 was applied onto the polyvinylpyrrolidone layer of the inkjet recording sheet obtained in Comparative Example 4 to a dry solid content of 5f/rT! An inkjet recording sheet was obtained by coating and drying. The results are also shown in Table 1.

Example 4 The formulation used in Example 2 was applied onto the cation-modified PVA layer of the inkjet recording sheet obtained in Comparative Example 5 so that the dry solid content was 10f/n11, and dried to obtain an inkjet recording sheet. I got it. The results are also shown in Table 1.

Examples 5 to 10 Art paper was used as the supporting substrate, and the modified PVA contained 2 mol of maleic anhydride units obtained by saponifying a copolymer of vinyl acetate and maleic anhydride, and the degree of saponification of the vinyl acetate units was Modified P with 93 molti and degree of polymerization 1800
Example 1 Using VA and further using glycerol polyglycidyl ether (a reaction product of glycerin and epichlorohydrin) as a water resistant agent in the ratio shown in Table 2.
An inkjet recording sheet was obtained in the same manner as above.

Table 2 shows the ink absorption speed, degree of bleeding, and water resistance of the obtained sheet.

2g2 Table Example 11 A coating solution with the following composition using high-quality paper as a supporting substrate and the formulation used in Example 1 was coated with a dry solid content of 20 r/
n? The recording sheet was coated with a bar coater and dried to obtain a recording sheet. The ink absorption speed, degree of bleeding, and water resistance of this sheet are shown in Section I.

Comparative Example 6 The same procedure as Example 11 was carried out except that the PVA used in Comparative Example 1 was used instead of the formulation used in Example 11. The results are also shown in Table 3.

Table 3 Example 12 A recording sheet was obtained by applying the formulation used in Example 2 to a dry solid content of 5 P/rfl'' using high-quality paper as a supporting substrate and drying it.Performance of this sheet are shown in Table 4.

Comparative Example 7 The same procedure as in Example 12 was carried out except that polyvinylpyrrolidone was used instead of the formulation used in Example 12. The pastes are also shown in Table 4.

Table 4

Claims (2)

[Claims] (1) An inkjet recording sheet with excellent water resistance, characterized in that the supporting substrate contains carboxyl-modified polyvinyl alcohol and a water-resistant agent containing two or more epoxy groups or ethyleneimine groups in the molecule. (2) The blending ratio of carboxyl-modified polyvinyl alcohol and a water-resistant agent containing two or more epoxy groups or ethyleneimine groups in the molecule is former/latter = 100
The inkjet recording sheet with excellent water resistance according to claim 1, wherein the water resistance is from /5 to 100/50.