JPH01139256A - Recording sheet - Google Patents

Abstract

PURPOSE:To provide a recording layer and enable excellent printing of characters and graphics by a pen plotter utilizing a water based ink or the like, by applying a mixed composition comprising hydrophilic monofunctional and multifunctional monomers and/or oligomers, and hardening the composition by irradiation with ionizing radiations. CONSTITUTION:An ionizing radiation-curable type hydrophilic monofunctional monomer and/or oligomer may be a carboxyl-containing monofunctional monomer or oligomer represented by, for example, an ethylenically unsaturated monocarboxylic acid or an ethylenically unsaturated polycarboxylic acid, whereas an ionizing radiation-curable type multifunctional monomer and/or oligomer is a monomer or oligomer having at least two inonizing radiation-curable unsaturated double bonds. A mixed composition containing these two materials is applied to a base, and is irradiated with inonizing radiations, whereby the two materials are efficiently copolymerized to form a recording layer comprising a hydrophilic hardened film having an appropriate crosslinked structure. By this, water absorptivity is obtained while maintaining water resistance, and a water based ink is rapidly absorbed and fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sheet that has excellent aptitude for recording with aqueous ink, and in particular has excellent aptitude for writing with aqueous pens, inkjet printing, etc.
The present invention relates to a recording sheet that is highly suitable for use in various types of printers that use water-based ink, such as pen blocks.

(Prior Art) Plastic films, metallized paper, metal foil, film laminated paper, etc. are currently used in various fields, but problems may occur depending on the use because they are inferior in recording suitability with water-based inks.

For example, plastic films are widely used as projection recording sheets for overhead projectors (hereinafter abbreviated as OHP) by copying characters and drawings from books, literature, etc. using electronic copying machines such as Xerox. However, text and drawings produced by such copiers are generally monochromatic, and it is effective to color them to make them visually appealing. There is a problem in that it cannot be written with a marker (coloring), and there is also a problem in that sufficient recording cannot be obtained even with an inkjet or water-based pen plotter using water-based ink.

Additionally, plastic films coated with resin such as polyester are also commercially available as OHP films to improve toner fixability and image density when used with electronic copying machines, but such films cannot be used with water-based inks. It has the drawbacks of poor writing and drying properties, and no absorbency or fixing properties.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problems, has excellent writing properties, absorbency, drying properties, and fixing properties of water-based ink, and allows writing and coloring with water-based pens and water-based markers. Furthermore, another object of the present invention is to provide a recording sheet that can be printed and printed with excellent quality using an inkjet printer, pen protector, etc. using water-based ink.

(Means for Solving the Problems) The present invention provides a method for forming (al) ionizing radiation-curable hydrophilic monofunctional monomers and/or oligomers and (bl ionizing radiation-curable polyfunctional monomers and/or oligomers) on a support. This is a recording sheet characterized in that a recording layer is formed by applying a mixed composition containing the above-mentioned composition and irradiating it with ionizing radiation.

(Function) The support used in the present invention is not particularly limited, and examples thereof include plastic films, metal foils, metallized paper, film laminated paper, coated paper, and plain paper. Although improvements can be made, plastic films are mainly used from the viewpoint of transparency, especially when used for OHP purposes. Plastic films include polypropylene, polyethylene,
Examples include polycarbonate, but when using an electronic copying machine, it is particularly desirable to use films with excellent heat resistance such as polyester, polysulfone, cellulose ester, polyamide, polyimide, etc.

In the present invention, first, <8) ionizing radiation-curable hydrophilic monofunctional monomer and/or oligomer and (b
(a) A mixed composition containing an ionizing radiation-curable polyfunctional monomer and/or oligomer is applied; (a) An ionizing radiation-curable hydrophilic monofunctional monomer or/and oligomer such as the following is used. can be mentioned.

(a) (meth)acrylic acid, CHw = CR-C
OO・(cHz 'CHR-COO)ll-H(n≧
1. R contains a carboxyl group represented by (meth)acrylic acid dimer, (meth)acrylic acid trimer, ethylenically unsaturated monocarboxylic acid, or ethylenically unsaturated polycarboxylic acid represented by H or CH3) Monofunctional monomers or oligomers containing carboxylic acid groups such as alkali metal salts, ammonium salts, and amine salts thereof.

(b) An amide group-containing monofunctional monomer or oligomer represented by ethylenically unsaturated (meth)acrylamide, alkyl-substituted (meth)acrylamide, N-vinylpyrrolidone, etc.

(c) Monofunctional monomers or oligomers containing sulfonic acid groups such as aliphatic or aromatic vinyl sulfonic acids, and monofunctional monomers or oligomers containing sulfonic acid groups such as alkali metal salts, ammonium salts, and amine salts thereof.

(d) OH group-containing monofunctional monomers or oligomers such as 2-hydroxyethyl (meth)acrylate.

(e) Epoxy group-containing monofunctional polymers or oligomers such as glycidyl (meth)acrylate.

(f) Quaternary ammonium base-containing monofunctional monomers or oligomers.

Among the above, (a) and (b) are particularly preferably used because they are excellent in the desired effects of the present application.

(b) Ionizing radiation-curable polyfunctional monomers and/or oligomers are not particularly limited as long as they have two or more ionizing radiation-curable unsaturated double bonds, such as hexanediol diacrylate, trimethylol, etc. Polyfunctional monomers such as propane triacrylate and pentane erythritol triacrylate, or polyfunctional oligomers such as ordinary polyester acrylate, epoxy acrylate, and urethane acrylate can also be used, but they have good copolymerizability with (a) and are efficient. It is desirable to have a well-crosslinked structure and a uniform crosslinking distribution.
Furthermore, those exhibiting hydrophilicity are preferable because they have good compatibility with the above-mentioned (a) and suitability for recording with aqueous inks.

Examples of such monomers or oligomers exhibiting hydrophilicity include the following.

(a) Ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, glycerin tri(meth)acrylate, etc. Representative polyhydric alcohols or polyhydric alcohol condensates and condensates of multiple (meth)acrylic acids.

(b) N,N'-methylenebis(meth)acrylamide (c) Polybasic acids and allyl alcohols represented by diallyl phthalate, diallyl maleate, diallyl terephthalate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, etc. ester of.

(d) By reacting acrylamide or an acrylamide derivative with a (di)aldehyde such as glyoxal in the presence of a catalyst, a small amount of radiation-reactive functional group (both H0H (R is a hydrogen atom or an alkyl group) is added to the side chain. A natural or synthetic water-soluble polymer compound that has been introduced with

Natural polymer compounds include casein, gelatin, starch polysaccharides (dextrin, soluble starch, pregelatinized starch, Brilan, etc.) and their derivatives, and cellulose derivatives [nitrocellulose, carboxymethylcellulose (cMC), methylcellulose (MC), etc.] ), hydroxypropyl methylcellulose (HPMC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC)
)and so on.

Examples of the synthetic polymer compound include completely saponified or partially saponified polyvinyl alcohol.

(e) Polyvinyl alcohol and the like having at least one functional group selected from a (meth)acryloyl group, a haloalkyl (meth)acryloyl group, and N-methylolacrylamide.

Among these, (a), (b), and (d) are preferably used because they are easily hardened by ionizing radiation.

The mixing ratio of these (a) ionizing radiation-curable hydrophilic monofunctional monomers and/or oligomers and (b) ionizing radiation-curable polyfunctional monomers and/or oligomers is as follows:
It is necessary to select the appropriate amount according to each type, but in general, if the proportion of (a) is small, sufficient writing and fixing properties of the water-based ink cannot be obtained, and if the proportion of (a) is too large, the water resistance of the recording layer will be poor. Since only products with inferior properties can be obtained, (a) in terms of weight ratio
: (b) is 98=2~20:80. Preferably 90
:10 to 50:50.

The reason why a sheet with excellent recording properties with water-based ink can be obtained in the present invention is that (a) and (b) are efficiently copolymerized to form a recording layer consisting of a hydrophilic cured film with an appropriate crosslinked structure. This is thought to be because the That is, since this recording layer has a hydrophilic network structure, it is assumed that it has water absorbing ability while maintaining water resistance, and water-based ink is quickly absorbed and fixed.

The reason why monofunctional monomers and/or oligomers were particularly selected as (a) ionizing radiation-curable hydrophilic monomers and/or oligomers is that polyfunctionality would result in too high a cured density, which would reduce the water absorption of the recording layer. This is because you will only get something that is inferior in ability.

In the present invention, when fc) a polymer having a hydrophilic group is further added to (a) and (a) above as a mixed composition for forming a recording layer, the effects of the present invention, i.e., the writability and fixation of aqueous ink, can be improved. - It is possible to suppress the occurrence of curls due to curing shrinkage after irradiation with ionizing radiation without impairing drying properties.

(c) Polymers having hydrophilic groups include, for example, carboxyl groups, sulfonic acid groups, carboxylic acid groups, sulfonic acid groups, hydroxyl groups, ether groups, acid amide groups, primary to tertiary amino groups, and quaternary ammonium groups. It is a polymer having hydrophilic groups such as.

(c) Polymers having hydrophilic groups are usually water-soluble, such as poly(meth)acrylic acid and its salts, polyvinyl alcohol, hydroxyethyl cellulose, carboxymethyl cellulose, starch, polyacrylamide,
Examples include polyvinylpyrrolidone, acrylic acid-vinyl alcohol copolymer, and the like.

In addition, in the recording sheet of the present invention, when a graft polymer and/or a block polymer having a hydrophilic segment is especially blended as the polymer having a hydrophilic group (c), the effect of the present invention, that is, the writability of the water-based ink is improved. ,
Fixing and drying properties are further improved, and curling due to curing shrinkage after irradiation with ionizing radiation can be suppressed.

The reason why the effect of the present invention is further improved by blending these graft polymers and/or block polymers is not necessarily clear, but the presence of these polymers increases the efficiency of copolymerization of (a) and (b). It is presumed that this is because it takes a crosslinked structure, which is often carried out and is more favorable in terms of ink absorption.

The above-mentioned graft polymer and/or block polymer are functionally separated polymers in which two or more types of segments with different properties exist in a separated form, unlike ordinary random polymers, and at least one of these segments is strongly hydrophilic. It is preferable that the material has a certain property.

Here, examples of segments having strong hydrophilicity include (meth)acrylic acid, acrylamide, N-methylolacrylamide, hydroxyethyl (meth)acrylate,
Examples include homopolymers such as vinylpyrrolidone and vinyl alcohol, and copolymers of two or more of these.

Specifically, graft polymers such as comb-shaped polymers in which branch chains are composed of polyN-methylolacrylamide, etc., and trunk chains are composed of copolymers of methyl methacrylate and hydroxyethyl medacrylate, polymethyl methacrylate, polyhydroxyethyl methacrylate, etc. Examples include hydrophilic block polymers having polyhydroxyethyl methacrylate segments and polymethyl methacrylate segments.

(c) The amount of the polymer having a tJl aqueous group is appropriately adjusted depending on the type, but the weight ratio is ((a) + (b)
)):(c) is 98:2 to 20:80. Preferably 90
:10-40:60 is used. On this occasion(
If the amount of c) is too small, a sufficient anti-curl effect cannot be obtained, and if it is too large, problems may arise, such as a decrease in water resistance of the recording layer or a decrease in coating film strength, depending on the type.

The coating compositions forming the recording layer of the present invention are (a) and (b).
Alternatively, the main components are (a), (b) and (c), but if necessary, antistatic agents, lubricants, dispersants, etc.
Dyes, pigments, anti-blocking agents, wetting agents, leveling agents, antifoaming agents, as well as other ionizing radiation curable resins not included in (a) and (b) and other polymers not included in <c>. It can also be added within a range that does not impede the effects of the present invention.

The coating composition thus prepared is applied to at least one side of the support by a conventional coating means such as a bar coater, roll coater, air knife coater, or gravure coater.

Coating compositions containing (a) and (b) may be prepared in an anhydrous or solvent-free manner, but generally when a polymer having a (cl hydrophilic group) is blended into the coating composition, water or It is necessary to dissolve and dilute with a solvent, and a coating composition based on a solvent such as water, methyl alcohol, ethyl alcohol, isopropyl alcohol, methyl cellosolve, or a mixed solvent thereof is used.

If the amount of water or solvent is small, the water or solvent may evaporate and dry when irradiated with ionizing radiation, but especially if the solid content concentration is low, drying may occur before and/or after ionizing radiation irradiation. Requires a process.

The coating amount of the above coating composition is 0.1 to 20 g/r in solid amount.
rr is preferably in the range of 0.5 to 10 g/cd.

Incidentally, if it is less than 0.1 g/n, the desired effect of the present invention is hardly obtained, and if it is more than 20 g/rrr, the effect is saturated and is not necessary.

The coated surface of the support may be pretreated as necessary by anchor coating treatment, corona discharge treatment, radiation treatment, plasma treatment, etc. to improve the wettability of the coated surface and the adhesion of the recording layer. can do.

In the recording sheet of the present invention, the coating composition layer formed as described above is cured by irradiation with ionizing radiation. Examples of ionizing radiation include electron beams, ultraviolet rays, alpha rays, beta rays, gamma rays, and X-rays. etc.

Since alpha rays, beta rays, gamma rays, and X-rays are associated with the problem of danger to the human body, electron beams and ultraviolet rays are preferably used because they are easy to handle and are widely used industrially.

When using an electron beam, the amount of electron beam irradiated is 0.1~
It is desirable to adjust within a range of about 20 Mrad. 0.
If it is less than 1 Mrad, sufficient irradiation effect cannot be obtained;
Irradiation in excess of Mrad is undesirable because it may deteriorate the support, especially paper and some types of plastics. As the electron beam irradiation method, for example, a scanning method, a curtain beam method, a broad beam method, etc. are adopted, and the acceleration voltage when irradiating the electron beam is 100 to 30
Approximately 0KV is appropriate. The electron beam irradiation method has higher productivity than ultraviolet irradiation, has no problems with odor or coloration due to the addition of a sensitizer, and has the advantage of easily forming a uniform crosslinked structure.

When using ultraviolet light, it is necessary to incorporate a sensitizer into the coating composition, such as thioxanthone, benzoin, benzoin alkyl ether xanthone, dimethylxanthone, benzophenone, anthracene, 2,2-jethoxyacetophenone, benzyldimethyl. ketal,
Diphenyl disulfide, anthraquinone, 1-chloroanthraquinone, 2-ethylanthraquinone, 2-te
r-butylanthraquinone, N,N'-tetraethyl-
One or more sensitizers such as 4,4'-diamylebenzophenone and 1,1-dichloroacetophenone are appropriately blended.

The amount of the sensitizer used is 0.2 to 10% by weight based on the ionizing radiation curable monomer/oligomer in the coating composition.
It is desirable to adjust the amount preferably within a range of about 0.5 to 5% by weight. Furthermore, in addition to such sensitizers, to accelerate curing, e.g. triethanolamine, 2-dimethylaminoethanol, dimethylaminobenzoic acid, isoamyl dimethylaminobenzoate, dioctylaminobenzoic acid, lauryl dimethylaminobenzoate, It is also possible to blend tertiary amines such as 0.05 to 3% by weight based on the ionizing radiation curable monomer/oligomer in the coating composition.

As a light source for ultraviolet irradiation, 1 to 50 ultraviolet lamps (for example, low-pressure, medium-pressure, high-pressure mercury lamps with operating pressures from several mm Hg to about 10 atmospheres), xenon lamps, tungsten lamps, etc. are used. , 5000-8
Ultraviolet light having an intensity of approximately 000 p W/cm'' is preferably irradiated.

(Example) The present invention will be explained in more detail with reference to Examples below.
Of course, it is not limited to these.

Note that unless otherwise specified, "parts" and "%" in the examples indicate "parts by weight" and "% by weight," respectively.

Example 1 The following mixed composition was coated on a polyethylene terephthalate film (thickness 100 μm) that had been subjected to anchor coating treatment with a thermosetting resin so that the dry weight was 4 g/m2, and then an electron beam irradiation device (electron beam irradiation device) was applied. curtain CB
A recording sheet was obtained by irradiating the recording sheet with an electron beam of 5 Mrad.

Mixed composition: (a) 100 parts of a 50% aqueous solution of acrylamide as an ionizing radiation-curable hydrophilic monofunctional monomer (
Polyethylene glycol diacrylate (KA) as a polyfunctional monomer curable by ionizing radiation
YARAD PEG400DA; manufactured by Nippon Kayaku ■) 25
and (c) a branched polyN-methylol acrylamide as a graft polymer having a hydrophilic segment;
A comb-shaped polymer (LH) whose backbone chain is composed of a copolymer of methyl methacrylate and hydroxyethyl methacrylate
48; Soken Kagaku side type) 25% methyl cellosolve solution 1
00 parts (solid content 25 parts) of the mixed composition.

Example 2 A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

Mixed composition: (a) 66 parts (solid content) of a 50% aqueous solution of acrylamide as an ionizing radiation-curable hydrophilic monofunctional monomer;
YARAD PEG400DA; manufactured by Nippon Kayaku ■) 33
and (c) a branched polyN-methylol acrylamide as a graft polymer having a hydrophilic segment;
A comb-shaped polymer (LH) whose backbone chain is composed of a copolymer of methyl methacrylate and hydroxyethyl methacrylate
48; 25% methyl cellosolve solution 1 (manufactured by Soken Kagaku ■)
33 parts (33 parts solids) of mixed composition.

Example 3 A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

Mixed composition: (a) 100 parts of a 50% aqueous solution of acrylamide as an ionizing radiation-curable hydrophilic monofunctional monomer (
(solid content: 50 parts), (b) 33 parts of polyethylene glycol diacrylate (KAYARAD PEG400DA; manufactured by Nippon Kayaku ■) as an ionizing radiation-curable polyfunctional monomer, and (c) a branched polymer as a graft polymer having a hydrophilic segment. 68 parts of a 25% methyl cellosolve solution (solid content: 17 parts) of a comb-shaped polymer (LH48; manufactured by Souken Kagaku ■) whose main chain is composed of poly N-methylol acrylamide and a copolymer of methyl methacrylate and hydroxyethyl methacrylate. Mixed composition.

Example 4 A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

Mixed composition = (a) 100 parts of a 50% aqueous solution of sodium acrylate with a degree of neutralization of 50% (solid content 50 parts) instead of 100 parts of a 50% aqueous solution of acrylamide as an ionizing radiation-curable hydrophilic monofunctional monomer. The same mixed composition as in Example 1 was used except that it was used.

Example 5 A recording sheet was obtained in the same manner as in Example 1 except that the mixed composition was as follows and was dried at 100° C. for 2 minutes after electron beam irradiation.

Mixed composition: (b) Polyethylene glycol diacrylate (KA
YARAD PEG400DA: Nippon Kayaku ■) 25
20% aqueous solution of modified polyvinyl alcohol having an OHOH functional group (AT-197, manufactured by Dainippon Ink & Chemicals) in place of 1
Same as Example 1 except that 25 parts (solid content: 25 parts) was used.

Example 6 A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

Mixed composition: (c) Instead of a comb-shaped polymer (LH48; manufactured by Souken Kagaku ■), which is a graft polymer having a hydrophilic segment, a hydrophilic block having a polyhydroxyethyl methacrylate segment and a polymethyl methacrylate segment is used. Modiper H, a polymer
A mixed composition similar to Example 1 except that 100 parts (solid content: 25 parts) of a 25% methyl cellosolve solution of 100 (manufactured by NOF ■) was used.

Example 7 A recording sheet was obtained in the same manner as in Example 1 except that the mixed composition was changed to the following.

Mixed composition: (c) Instead of using a comb-shaped polymer (LH48; manufactured by Souken Kagaku ■), which is a graft polymer having a hydrophilic segment, (c) a quaternary acrylic acid, which is a polymer having a hydrophilic group; Gosefheimer C-8, an ammonium salt ester/styrene copolymer
83 parts of 30% aqueous solution of 20 (Nippon Gosei Chemical Industry side type) (
A mixed composition similar to Example 1 except that 25 parts of solid content was used.

Example 8 The following mixed composition was heated at 100°C before electron beam irradiation.
A recording sheet was obtained in the same manner as in Example 1, except that it was dried for 15 seconds.

Mixed composition: (c) Instead of using a comb-shaped polymer (LH48; manufactured by Souken Kagaku ■), which is a graft polymer having a hydrophilic segment, (c) polyvinyl alcohol (PVA-), which is a polymer having a hydrophilic group, is used. 1)7;
250 parts of a 10% aqueous solution (solid content: 25 parts) of Kuraray ■
The same mixed composition as in Example 1 except that .

Example 9 A recording sheet was obtained in the same manner as in Example 1 except that the mixed composition was changed to the following.

Mixed composition = (a) 170 parts of a 50% aqueous solution of acrylamide as an ionizing radiation-curable hydrophilic monofunctional monomer (
(solid content: 85 parts), (b) polyethylene glycol diacrylate (as an ionizing radiation-curable polyfunctional monomer)
KAYARAD PEG400DA; manufactured by Nippon Kayaku ■)
A mixed composition consisting of 15 parts and 0.02 parts of Florado FC170G (manufactured by Jujutsu 3M ■) as a wetting agent.

Example 10 A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

Mixed composition: [a) 50% of sodium acrylate with a degree of neutralization of 50% as an ionizing radiation-curable hydrophilic monofunctional monomer
Using 170 parts of an aqueous solution (solid content: 85 parts), (b) 15 parts of diethylene glycol diacrylate as an ionizing radiation-curable polyfunctional monomer and Florado F as a wetting agent.
A mixed composition consisting of 0.02 part of C170C (manufactured by Jujutsu 3M ■).

Example 1) A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

Mixed composition = (a) 90 parts of a 50% aqueous solution of acrylamide (solid content: 45 parts) and 40 parts of N-vinylpyrrolidone instead of 100 parts of a 50% aqueous solution of acrylamide as an ionizing radiation-curable hydrophilic monofunctional additive. A mixed composition consisting of 15 parts of diethylene glycol diacrylate as an ionizing radiation-curable polyfunctional monomer and 0.02 part of Florard FC170C (manufactured by Sumitomo 3M ■) as a wetting agent.

Comparative Example 1 A recording sheet was obtained in the same manner as in Example 1 except that the mixed composition was changed to the following.

Mixed Composition A mixed composition in which 0.02 part of Florard FC170C (manufactured by Jujutsu 3M) was added as a wetting agent to 200 parts of a 50% aqueous solution of niacrylamide.

Comparative Example 2 A recording sheet was obtained in the same manner as in Example 1, except that the coating composition was changed to the following.

Coating composition: polyethylene glycol diacrylate (
KAYARAD PEG400DA; manufactured by Nippon Kayaku ■)
was used as a coating composition.

Comparative Example 3 A recording sheet was obtained in the same manner as in Example 1, except that the coating composition was changed to the following.

Coating composition Gocefaimer C-82, which is a quaternary ammonium salt of acrylic acid ester/styrene copolymer
A 30% aqueous solution of 0 (manufactured by Nippon Gosei Kagaku Kogyo ■).

Comparative Example 4 A recording sheet was obtained in the same manner as in Example 1, except that the coating composition was changed to the following.

Coating composition: A comb-shaped polymer (L
H48; 25% methyl cellosolve solution (manufactured by Souken Kagaku ■).

Comparative Example 5 A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

Mixed composition: polyethylene glycol diacrylate (
KAYARAD PEG400DA; manufactured by Nippon Kayaku ■)
30 parts and comb-shaped polymer (LH48; manufactured by Souken Kagaku ■)
A mixed composition of 280 parts of a 25% methyl cellosolve solution (solid content 70 parts).

Comparative Example 6 A recording sheet was obtained in the same manner as in Example 1, except that the mixed composition was changed to the following.

100 parts of a 50% aqueous solution of mixed composition niacrylamide (
A mixed composition of 200 parts of a 25% methyl cellosolve solution (solid content: 50 parts) of a comb-shaped polymer (LH48; manufactured by Souken Kagaku ■).

Comparative Example 7 Polyethylene terephthalate film (thickness: 10 mm) treated with thermosetting resin anchor coating.

μm).

Comparative Example 8 Polyethylene terephthalate film (thickness 100 μm) not subjected to thermosetting resin anchor coating treatment.

The 19 types of recording sheets obtained as described above were evaluated in terms of writing performance of water-based ink, fixation/drying property of water-based ink, water resistance, solvent resistance, and curling suitability as follows, and the results were evaluated. It is shown in Table 1.

[Writability of water-based ink]

It was written on a recording sheet using a water-based marker (manufactured by KOKUYO Co., Ltd.), and the presence or absence of flickering was visually determined.

◎: No repelling occurred at all.

O: Although there was some repelling, it was at a level that caused no practical problems.

△: There was repellency and the level was problematic in practice.

×: It was difficult to write due to the sharpness.

[Fixing/drying properties of water-based ink] After writing on a recording sheet using a water-based marker (manufactured by KOKUYO Co., Ltd.), the time required for the ink to be fixed was evaluated by rubbing lightly with a finger.

It was fixed within 0.025 seconds.

It was fixed within 0.760 seconds and was at a level that caused no practical problems.

Δ: Fixing took 60 seconds to 24 hours, which was at a level that was problematic in practice.

×: It was not fixed even after 24 hours, and a record could be taken by rubbing with a finger.

〔water resistance〕

Damage to the recording layer was evaluated after 5 drops of water were dropped onto the recording layer using a dropper and wiped off with gauze.

O: There was no damage to the recording layer at all.

Δ: There was damage to the recording layer, which was at a level that caused problems in practice.

x: The entire recording layer was wiped off.

[Solvent resistance]

Damage to the recording layer was evaluated after 5 drops of ethanol was dropped onto the recording layer using a dropper and wiped off with gauze.

○: There was no damage to the recording layer at all.

×: There was damage to the recording layer, which was at a level that caused problems in practical use.

[Curling suitability]

The curl height when the recording sheet was cut into A4 size and placed on a horizontal table was expressed in mm.

■=Curl height 3mm or less.

○: Curl height 3 to 1Qmm.

Δ: Curl height 10 to 20 mm.

Table 1 (Effects) The present invention has excellent writing properties, fixing and drying properties of water-based ink,
In addition, the recording sheet had a recording layer with excellent water resistance and solvent resistance, and the one in which a wood-loving polymer was blended in the mixed composition forming the recording layer also had excellent curling properties.

Claims (3)

[Claims] (1) A mixed composition containing (a) an ionizing radiation-curable hydrophilic monofunctional monomer or/and oligomer and (b) an ionizing radiation-curable polyfunctional monomer or/and oligomer is applied onto a support. A recording sheet comprising a recording layer formed by irradiation with ionizing radiation. (2) The recording sheet according to claim (1), wherein the mixed composition contains (c) a polymer having a hydrophilic group. (3) The recording sheet according to claim (2), wherein the polymer having a hydrophilic group (c) is a graft polymer and/or a block polymer having a hydrophilic segment.