JPS63183874A - Ink jet recording sheet superior in water resistance - Google Patents

Abstract

PURPOSE:To obtain an ink jet recording sheet superior in transparency, by a method wherein a cationic water-soluble resin and an anionic water-soluble resin are contained in a substrate in the molar ratio of the both radical ions ranging 1/4-4/1. CONSTITUTION:As a cationic water-soluble resin, polyvinyl pyridine, polyvinyl imidazole, cation-modified polyvinyl alcohol, and others are used. As an anionic water-soluble resin, poly(met)acrylic acid, anion-modified PVA, CMC, and others are cited. As the combination of these resins, the cation-modified PVA and the anion-modified PVA are preferably combined from the standpoint of water resistance. Additionally, it is necessary that the use ratio of the cationic water- soluble resin and the anionic water-soluble resin is selected from the molar ratios of the both radical ions ranging 1/4-4/1. As a transparent substrate, a film or sheet made of polyester, polystyrene, or the like or a high-transparency paper is used.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application 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 for inkjet and jet recording systems. However, as the performance of inkjet recording machines improves, such as faster recording and multicolor recording, sheets for inkjet recording are also required to have more advanced properties. Firstly, the ink absorption speed is high; secondly, the diameter of the ink dots does not become larger than necessary; and thirdly, the inkjet recording sheet itself has high water resistance.

In order to meet these requirements, various studies have been made (such as using paper or water-soluble resin as an absorbing material for water-soluble inkjet ink), but increasing the ink absorption speed may result in the ink dot diameter becoming larger than necessary. There were some drawbacks, such as the water resistance being significantly lower.

In addition, a water-soluble polymer having an anionic hydrophilic group or a water-soluble polymer having a cationic hydrophilic group is used alone, and these 6i! A method of forming a layer (Japanese Unexamined Patent Publication No. 60-17] 143) has also been disclosed, but in this case there is a problem that the water resistance is still insufficient.

An object of the present invention is to provide an inkjet recording sheet that satisfies the above-mentioned requirements and is particularly excellent in ink absorbency and water resistance.

Yet another object of the present invention is to create a transparent display that can be used for observation by projecting a recorded image onto a screen or the like using an optical device such as a slide or OHP, or for observation of transmitted light such as a color display. Our objective is to provide an excellent inkjet recording sheet.

The present inventors have solved the above-mentioned problems and, as a result of intensive studies to achieve the above-mentioned objects, have determined that the molar ratio of the cationic water-soluble resin and the anionic water-soluble resin to the supporting substrate is the same as that of the amphoteric groups] The present inventors have discovered that an inkjet recording sheet with excellent ink absorbency and extremely excellent water resistance can be obtained when the content is in the range of /4 to 4/1, and the present invention has been completed.

The cationic water-soluble resin used in the present invention includes polyvinylpyridine, polyvinylimidazole, polyethyleneimine, polyvinylamine, polyallylamine, polyallylamine sulfone copolymer or ammonium salt thereof, cationized starch, cationized poly(
meth)acrylamide, cation-modified polyvinyl alcohol (hereinafter polyvinyl alcohol is abbreviated as PVA)
etc. can be mentioned.

Examples of the anionic water-soluble resin include poly(meth)acrylic acid, salts thereof, copolymers of (meth)acrylic acid, anion-modified PVA, and CMC.

As the combination of the above-mentioned cationic water-soluble resin and anionic water-soluble resin, a combination of cation-modified PVa and anion-modified PVA is preferably used from the viewpoint of water resistance.

The above-mentioned modified PVA can generally be obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a carboxyl group, a sulfonic acid group, and an ammonium group and a vinyl ester.

Here, the ethylenically unsaturated monomer having a carboxyl group includes ethylenically unsaturated carboxylic acids or salts thereof such as rotonic acid, itaconic acid, monomethyl maleate, acrylic acid, methyl acrylate, and maleic anhydride;
Or its lower alkyl ester or acid anhydride.

Examples of the ethylenically unsaturated monomer having a sulfonic acid group include ethylenically unsaturated sulfonic acids or salts thereof such as vinylsulfonic acid, allylsulfonic acid, and N-(meth)acrylamidopropanesulfonic acid.

Further, as the ethylenically unsaturated monomer having an ammonium base, specifically, trimethyl-3-(1-(meth)
acrylamide-1,1-dimethylpropyl) ammonium chloride, trimethyl-3-(1-(meth)acrylamido-1,1-dimethylethyl) ammonium chloride, trimethyl-3-(1-(meth)acrylamidopropyl) ammonium chloride, Examples thereof include N-vinylimidazole, N-vinyl-N-methylimitasole, and quaternized products thereof.

The content of anionic or cationic group units in the modified PVA is preferably in the range of 0.1 to 10 mol%. Further, depending on the purpose, it is not necessary to further copolymerize other ethylenically unsaturated monomers. In this case, the content of other ethylenically unsaturated monomer units may be as long as the modified PVA is water-soluble and varies depending on the content of ionic group units and the degree of saponification, but is usually 0. A range of 1 to 10 mol % is desirable.

The degree of saponification of the vinyl acetate unit of the modified PVΔ may vary depending on the content of ionic groups or may be water-soluble, and is usually selected from the range of 50 to 100 mol%, preferably 70 to 99 mol%. The degree of polymerization of modified PVA is not particularly limited and is appropriately selected depending on the purpose, but is usually ILIO to
A range of 3000 is used.

In the present invention, the usage ratio of the cationic water-soluble resin and the anionic water-soluble resin is such that the molar ratio of the amphoteric groups is 1/4.
It is necessary to select from the range of 1/3 to 3/14, more preferably 1/2 to 2/1. If the molar ratio of the amphoteric groups is outside the range of 1/4 to 4/1, sufficient water resistance cannot be obtained.

The composition of the cationic water-soluble resin and the anionic water-soluble resin used in the present invention in a specific ratio can be used alone, or can be further combined with water-soluble materials such as ordinary PVA, polyacrylamide, starch, cellulose derivatives, etc. Water-dispersible resins such as polymers, 8BB latex, N15B latex, vinyl acetate emulsion, ethylene/[1 vinyl copolymer emulsion, (meth)acrylic ester emulsion, and vinyl chloride emulsion can also be used together. Colander. The proportion used in combination is 50% by weight or less, preferably 20% by weight or less, based on the weight part of the water-soluble resin composition having an ionic group.

Furthermore, the water-soluble resin composition having an ionic group used in the present invention may be used in combination with fillers such as silica, clay, talc, diatomaceous earth, zeolite, calcium carbonate, alumina zinc oxide, and sathion white. You can also do it. In this case, the ratio of the water-soluble resin composition/filler having an ionic group of the present invention is usually 1/10 to 100 by weight, although it differs depending on the recording sheet with excellent transparency and other cases. /1, preferably 5/1oo~1
Selected from a range of 15 old elephants.

The water-soluble resin composition having an ionic group used in the present invention has excellent ink absorption properties and can be used as an ink absorption layer, but it can also be used as an ink absorption layer made of other ink absorption materials. It is also possible to form a layer made of the composition on top and use it as a water-resistant Jm.

21. used in the present invention. As the supporting substrate, any conventionally known transparent or opaque supporting substrate can be used. Examples of transparent supporting substrates include films and sheets of polyester, polystyrene, polyvinyl chloride, polymethyl methacrylate, cellulose acetate, polycarbonate, polyimide, cellophane, celluloid, and highly transparent paper. Examples of the opaque support substrate include general paper, pigment-coated paper, cloth, wood, metal plate, synthetic paper,
Examples include synthetic resin films or sheets that have been opaquely treated.

In the case of an inkjet recording sheet with 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 making the supporting substrate contain a composition of a cationic water-soluble resin and an anionic water-soluble resin in a specific ratio includes an aqueous solution of the above-mentioned composition, or other water-soluble or water-dispersible resin, or filling. An aqueous solution or aqueous dispersion of the mixture with the material is impregnated into the supporting substrate using a conventional coating method such as a size press, air knife coater, roll coater, bar coater, or blade coater, or it is coated on the upper surface of the supporting substrate or on the upper and lower surfaces of the supporting substrate. A method such as forming a coating layer on both surfaces can be used.

In addition, when the supporting substrate is paper, the above-mentioned method of internally adding an aqueous solution or aqueous dispersion during paper making may also be used.

After being impregnated or coated in the manner described above, it is then dried. The drying temperature at this time is 60℃~18L1℃,
Preferably 80°C to 15t1°C, more preferably tUO
It is selected from the range of °C to 130 °C. If the drying temperature is less than 60°C, it is difficult to develop water resistance, and if it exceeds 180°C, the ink absorbency tends to decrease.

The content of the above-mentioned composition in the inkjet recording sheet of the present invention is not particularly limited, but is usually u, 1 to 2.
u o a/nl, preferably 1 to l (l U Q
/yl is used.

E0 action and effects of the present invention The inkjet recording sheet of the present invention has excellent ink absorption properties and extremely excellent water resistance. The reason why an inkjet recording sheet having the above-mentioned excellent performance can be obtained is not fully elucidated, but is presumed to be as follows.

That is, it is presumed that the cationic water-soluble resin and anionic water-soluble resin used in the present invention form an ionic complex during the heat drying process, forming an aqueous and water-insoluble film.

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, "%" and "part" represent weight basis.

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

(1) Inkjet Recording Method Color inkjet recording was performed using the following four color inks using a recording apparatus having an on-demand inkjet recording head with an ejection orifice diameter of 60 μm, and the recording characteristics were evaluated.

Yellow ink (composition) 0.1. Acid Yay - 2,32 parts diethylene glycol 30 parts water
70 parts Magenta ink (composition) ・O, 1, Acid Red 32 2N diethylene glycol 30 parts Water
70 parts Cyan ink (composition) C01, Direct Blue 86 2 parts diethylene glycol 30 parts water
70 copies black ink (
Composition] U, 1. Direct black 19 2 parts diethylene glycol 3 () gamma-hydrogenated water
70 copies (2) Ink absorption speed After inkjet recording, 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.

The diameter of the printed dot was measured using a stereomicroscope to show how many times larger it was than the ink droplet. The lower the magnification, the less blurring.

(4) Transparency The visible light transmittance of the non-printed portion of the inkjet recording sheet was measured using a spectrophotometer using visible light having a wavelength of 5 υg 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: Smudged or dissolved.

Example 1 A monomer having a cationic group obtained by saponifying a copolymer of trimethyl-3-(1-methacrylamidobrobyrne ammonium chloride and vinyl acetate) was placed on a transparent polyester sheet of 50 μm thick (9596). The saponification degree of vinyl acetate units is 88 mol% at a content of 3 mol% of vinyl acetate units. The content of monomer units having groups is 2 mol%, the degree of saponification of vinyl acetate units is 88 mol%, polymerization jJj175
0 modified PVA [cationic group/carboxyl group]
1()% of the composition blended to have a molar ratio of 271
The coating amount after drying the aqueous solution was 159. It was coated in a uniform manner and dried at 120° C. for 2 minutes to obtain an inkjet recording sheet. Table 1 shows the ink absorption speed, degree of bleeding, transparency, and water resistance of this sheet.

Comparative Examples 1 to 4 Comparative examples were carried out in the same manner as in Example 1 except that the following resins were used in place of the composition used in Example 1. The results are also shown in Table 1.

Resin used in Comparative Example 1: Only cation-modified 1'VA used in Example 1.

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

Resin used in Comparative Example 3: Modified PV used in Example 1
A composition containing A in a molar ratio of [cationic group/carboxyl group] of 571.

Resin used in Comparative Example 4: Modified PV used in Example 1
A composition containing A in a molar ratio of [cationic group/carboxyl group] of 115.

Example 2 A sheet for inkjet recording was obtained in the same manner as in Example 1 except that art paper was used as the support substrate. The performance of this sheet is shown in Table 2.

Examples 3 to 7 The same procedure as in Example 2 was conducted except that the modified PVA used in Example 2 was used in the composition shown in Table 2 instead of the composition used in Example 2.

The results are also shown in Table 2.

Tokuhan Applicant: CLAN Co., Ltd.

Claims (2)

[Claims] (1) Water resistance characterized in that the supporting substrate contains a cationic water-soluble resin and an anionic water-soluble resin in a molar ratio of amphoteric groups of 1/4 to 4/1. Excellent inkjet recording sheet. (2) The inkjet recording sheet with excellent water resistance according to claim 1, wherein the cationic water-soluble resin is cation-modified polyvinyl alcohol, and the anionic water-soluble resin is anion-modified polyvinyl alcohol.