JPH08169172A - Ink-jet recording sheet - Google Patents

Abstract

PURPOSE: To provide an ink-jet recording sheet which has high printing density, good ink absorption, light resistance of an image, and a non-yellowing property of blank parts. CONSTITUTION: An ink-jet recording sheet in which an ultraviolet absorbing cationized polymer from a copolymer of a polymerizable vinyl compound having quaternary ammonium base and a polymerizable vinyl compound having a structural unit with ultraviolet absorbing power is incorporated into neutral paper containing 3-20wt.% (to pulp) of calcium carbonate as a filler and alkyl ketene dimer or alkenyl succinic anhydride as an internal sizing agent. Preferably, the structural unit with ultraviolet absorbing power is 2- hydroxybenzophenone residue or 2-hydroxybenzotriazol residue.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording sheet, and more particularly, an ink jet ink having a high printing density, excellent ink absorbency and light fastness of an image, and excellent yellowing resistance of a white paper portion. It concerns recording sheets.

[0002]

2. Description of the Related Art The ink jet recording system is a system in which minute droplets of ink are ejected by various operating principles to adhere to recording paper such as paper to record images, characters, etc., but at high speed and low noise. , Easy to multicolor, great flexibility of recording pattern, no need for development-fixing,
As a recording device for various figures including Kanji and color images, it is rapidly spreading in various applications. further,
An image formed by the multicolor inkjet system can obtain a print comparable to that of the multicolor printing by the plate making system or the printing by the color photographic system. Also,
For applications requiring a small number of copies, it is being widely applied to the field of full-color image recording because it is cheaper than the photographic technique.

When an ink jet recording sheet is viewed from the surface of the recording paper, in order to obtain a high quality image, the ink adhered on the recording paper mainly made of pulp does not spread irregularly on the surface, and It needs to be absorbed promptly.

Therefore, for the purpose of improving the ink absorbency, a recording paper having a high water absorbency such as non-size paper is conventionally used on the basis of acid paper, or an absorbent coating layer such as silica is used. To install (Japanese Patent Publication No. 60-275)
88 and 63-65037) have been proposed.

However, since such a coating type ink jet recording sheet has a coating layer containing silica as a main component on its surface, it impairs the natural feeling of the recording sheet and is high in cost. There is an increasing demand for such a plain paper type that has excellent ink absorbency and high printing density. Regarding the sharpness of the recorded image, the sizing of the recording sheet affects the recorded image, and when the sizing is low, the water-based ink sinks in the recording sheet, and the spread of recording dots and feathering may occur. A so-called whisker-like blur is likely to occur.

On the other hand, in the case of an ink jet recording sheet, various improvements have been conventionally made to prevent yellowing of the recording sheet itself or to improve the light resistance of a recorded image.

A method for coating a surface of a base paper with a cationic resin comprising a polyalkylene polyamine dicyandiamide ammonium salt condensate for improving the light resistance of recorded images, preventing yellowing of white paper, and improving water resistance (Japanese Patent Publication No. 2-35675). ) Is proposed.

However, the ink jet recording sheet is often exposed to various environmental conditions such as ultraviolet rays and temperature / humidity during storage or handling of the recording sheet before or after recording. Further, there are various handling methods such as storing the recording sheet in a file of polyethylene, polypropylene, vinyl chloride resin or the like, attaching an adhesive tape, or the like.

Various materials such as polyethylene, polypropylene, vinyl chloride resin files, adhesives, glues, rubbers, etc. are stable against light and heat by the addition of phenolic antioxidants and hindered amine light stabilizers. Have been converted. Many polypropylenes, polyethylenes and the like have kneaded and mixed with an antioxidant having a phenol group in the molecule such as butylhydroxytoluene (hereinafter abbreviated as BHT). These phenolic antioxidants are oxidized to give quinone. It is well known that the structure makes it yellow.

A large amount of filler (inorganic pigment) is internally added to the base paper, that is, the ink jet recording sheet, but when the recording sheet is in contact with the above material such as a polyethylene file for a long time, it is contained in the above material. The phenolic antioxidant present is volatilized and is absorbed by the filler in the recording sheet,
This will be oxidized and the recording sheet itself will turn yellow.

[0011]

SUMMARY OF THE INVENTION From the above, it is an object of the present invention to provide an ink jet recording sheet having high printing density, excellent ink absorbency and light fastness of an image, and excellent yellowing resistance of a white paper portion. It is a thing.

[0012]

DISCLOSURE OF THE INVENTION As a result of intensive studies in view of the above, the present inventor has invented the ink jet recording sheet of the present invention. That is, the ink jet recording sheet of the present invention is mainly composed of wood pulp and a filler, containing 3 to 20% by weight of calcium carbonate as a filler (to pulp) and an alkyl ketene dimer or alkenyl succinic anhydride as an internally added sizing agent. A neutral paper containing an ultraviolet-absorbing cationized polymer comprising a copolymer of a polymerizable vinyl compound having a quaternary ammonium salt group and a polymerizable vinyl compound having a structural unit having an ultraviolet-absorbing ability. It is what

In the ink jet recording sheet of the present invention, preferably, the structural unit having an ultraviolet absorbing ability is a 2-hydroxybenzophenone residue or a 2-hydroxybenzotriazole residue.

The ink jet recording sheet of the present invention will be described in detail below. The inkjet recording sheet of the present invention may contain a filler in an amount of 3 to 20% by weight, preferably 5 to 17% by weight, based on pulp. Inorganic pigments such as calcium carbonate, talc, kaolin, and titanium dioxide are generally used as the type of filler, but when printing is performed by an inkjet recording method, dot spreading and whisker-shaped whiskers called feathering are used. From the viewpoint of preventing the occurrence of bleeding, calcium carbonate is particularly preferable.

Here, when the content of the filler is less than 3% by weight, when printing is carried out by an ink jet recording method using a water-based ink, permeation of the ink into the recording sheet is suppressed so that the water-based ink dries slowly. There is a problem of becoming. On the other hand, if it exceeds 20% by weight, the ink permeability in the ink jet recording method is too large and the print density is lowered.

There is a certain degree of correlation between the printability of the ink jet recording method using aqueous ink and the size property of the ink jet recording sheet. The Steckigt sizing degree is preferably 5 to 25 seconds from the viewpoint of printability. Here, when the Steckigt sizing degree is 5 seconds or less,
When printing is performed by the ink jet recording method using a water-based ink, the ink sinks because the ink penetrates too much into the paper, which not only lowers the print density but also refers to dot spread and feathering. Whisker-like bleeding easily occurs. Further, when the Steckigt sizing degree is 25 seconds or more, the drying property of the ink becomes slow.

As means for controlling the permeability of the water-based ink by the ink jet recording method, a method of changing the compounding amount of the internally added sizing agent, an acrylic acid-based agent in the size press liquid,
A method of adding a surface sizing agent such as an α-olefin type or styrene-maleic acid type, a method of adding a surfactant to the size press liquid, and the like can be used.

Further, by changing the blending amount of the internally added sizing agent,
There is also a method of changing the size of the base paper itself. As the internally added sizing agent, one or more of known sizing agents such as alkyl ketene dimer, alkenyl succinic anhydride, styrenic polymer and neutral rosin sizing agent classified for neutral papermaking are appropriately used. Used in combination.

In the UV-absorbing cationized polymer of the present invention, structural units having UV-absorbing ability, that is, 2-hydroxybenzophenone residue, 2-hydroxybenzotriazole residue and the like are bonded to the main chain of the polymerizable vinyl compound monomer. And a polymerizable vinyl compound having a quaternary ammonium salt group bonded thereto.

The copolymerization ratio (p / q) in the copolymer of the polymerizable vinyl compound (p) having a structural unit having ultraviolet absorbing ability and the polymerizable vinyl compound (q) having a quaternary ammonium salt group is , Can be set appropriately. The water-soluble or self-dispersible UV-absorbing cationized polymer can be obtained by changing the ratio of p and q. For example, when the ratio of the polymerizable vinyl compound to which a quaternary ammonium salt group is bound is reduced, the water-soluble type is shifted to the self-dispersible type.

As the structural unit having an ultraviolet absorbing ability,
A 2-hydroxybenzophenone derivative, a 2-hydroxybenzotriazole derivative, a salicylic acid derivative, a cyanoacrylate derivative, and the like, preferably a 2-hydroxybenzophenone derivative and a 2-hydroxybenzotriazole derivative can be mentioned. For example, they are exemplified as follows. be able to.

1) 2-hydroxybenzophenone derivative 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4-methoxy-5-sulfo Benzophenone, 2,
4-dihydroxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, bis (2
-Methoxy-4-hydroxy-5-benzoylphenyl) methane, 2-hydroxy-4-acryloyloxybenzophenone, 2-hydroxy-4-methacryloyloxybenzophenone, 2-hydroxy-4- (2-acryloyloxy) ethoxybenzophenone, 2 -Hydroxy-4- (2-methacryloyloxy) ethoxybenzophenone, 2-hydroxy-4- (2-methyl-2)
-Acryloyloxy) ethoxybenzophenone and the like.

2) 2-Hydroxybenzotriazole derivative 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-5'-t-)
Butylphenyl) benzotriazole, 2- (2'-hydroxy-5'-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-
3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-
3 ', 5'-di-t-amylphenyl) benzotriazole, 2- {2'-hydroxy-3'-(3 ", 4",
5 ", 6" -tetrahydrophthalimidomethyl) -5 '
-Methylphenyl} benzotriazole, 2,2-methylenebis {4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol}, 2- {2'- Hydroxy-5 '-(methacryloyloxy) phenyl} benzotriazole, 2-
{2'-hydroxy-5 '-(acryloyloxy) phenyl} benzotriazole, 2- {2'-hydroxy-3'-t-butyl-5'-(methacryloyloxy)
Phenyl} benzotriazole, 2- {2'-hydroxy-3'-methyl-5 '-(acryloyloxy) phenyl} benzotriazole, 2- {2'-hydroxy-
5 '-(methacryloyloxypropyl) phenyl}-
5-chlorobenzotritriazole, 2- {2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl} benzotriazole, 2- {2'-hydroxy-
5 '-(acryloyloxyethyl) phenyl} benzotriazole, 2- {2'-hydroxy-3'-t-butyl-5'-(methacryloyloxyethyl) phenyl} benzotriazole, 2- {2'-hydroxy-
3'-methyl-5 '-(acryloyloxyethyl) phenyl} benzotriazole, 2- {2'-hydroxy-5'-(methacryloyloxypropyl) phenyl}
-5-chlorobenzotriazole, 2- {2'-hydroxy-5 '-(acroyloxybutyl) phenyl}-
5-methylbenzotriazole, {2-hydroxy-3
-T-butyl-5- (acryloyloxyethoxycarbonylethyl) phenyl} benzotriazole and the like.

3) Salicylic Acid Derivatives Phenyl salicylate, pt-butylphenyl salicylate, p-octylphenyl salicylate and the like.

4) Cyanoacrylate-based derivatives 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate, ethyl-2-cyano-3,3'-diphenyl acrylate and the like.

The polymerizable vinyl compound having a quaternary ammonium salt group is a polymerizable vinyl compound having a copolymerizable polymerizable vinyl compound having a tertiary amino group in the molecule as a monomer and a structural unit having an ultraviolet absorbing ability. After being copolymerized with a compound, the amino group is quaternized with an alkylating agent, or the tertiary amino group of the monomer is converted into a quaternary ammonium salt with an alkylating agent in advance, and then this is copolymerized. By doing so, it can be introduced into the ultraviolet absorbing cationized polymer.

Examples of the copolymerizable polymerizable vinyl compound having a tertiary amino group in the molecule include N, N-dimethylaminopropyl acrylate, N, N-diethylaminoethyl acrylate and N, N-dimethylaminoethyl methacrylate. , N, N-diethylaminoethyl methacrylate, N, N-dimethylaminopropyl methacrylate, N, N-dimethylaminobutyl methacrylate, N, N-dimethylaminoethyl acrylate, N,
N-dimethylaminopropyl acrylamide, N, N-
Examples thereof include dimethylaminoethylacrylamide, acryloylmorpholine, N-2-hydroxy-3-acryloyloxypropyl-N, N-dimethylamine, N-3-methacryloyloxy-2-hydroxypropyl-N, N-diethylamine and the like.

Examples of the alkylating agent for converting the amino group of the polymerizable vinyl compound having a tertiary amino group into a quaternary ammonium salt include halogenated alkyls such as benzyl chloride and methyl chloride; sulfuric acid such as dimethyl sulfuric acid and diethyl sulfuric acid. Examples thereof include esters, and the betaine-type quaternary ammonium group can be obtained by reacting with monochloroacetic acid, β-propiolactone and the like.

Examples of the polymerizable vinyl compound containing a quaternary ammonium salt group include glycidyl trimethyl ammonium chloride, 3-chloro-2-hydroxypropyl trimethyl ammonium chloride, and 3-chloro-2-hydroxypropyl trimethyl ammonium chloride.
Chloro-2-hydroxypropyltriethanolammonium chloride, glycidyldimethylbenzylammonium chloride, glycidyldimethylbutylammonium chloride, N-2-hydroxy-3-acryloyloxypropyl-N, N, N-trimethylammonium chloride, N-methacryloylaminoethyl -N,
N, N-dimethylbenzyl ammonium chloride, N
-Methacryloxy-N, N, N-triethylammonium ethyl sulfuric acid and the like can be mentioned.

As described above, in the ink jet recording sheet of the present invention, the ultraviolet ray absorbing cationized polymer is contained in the base paper mainly composed of the wood pulp and the filler, so that a yellowing phenomenon occurs in the white paper portion of the ink jet recording sheet. Can be prevented, and the light resistance of the recorded image can be remarkably improved. It is presumed that this is because the cationized polymer strongly adheres to the base paper while maintaining the ultraviolet absorbing ability.

The yellowing of the ink jet recording sheet with respect to the white paper portion can be simplified by using BHT dimer (4,4'-methylenebis-2,6-di-t-butylphenol) which is considered as one of the causes. The characteristic of yellowing with respect to the inkjet recording sheet can be estimated.

Specifically, a 1% alcohol (ethanol, isopropyl alcohol, etc.) solution of a BHT dimer was spotted on an ink jet recording sheet so as to have a solid content of 0.5 g / m ^2. Dried, 20
It can be left for 3 days under the condition of 65 ° C. and RH, and L ^* a ^* b ^* (a colorimetric method according to CIE) before and after the standing can be measured by a color difference meter (CR100: manufactured by Minolta). Here, the degree of yellowing is the difference between b ^* before and after the treatment (△
b ^*) can be determined from, small enough yellowing less numerically, △ b ^* is preferably 15 or less, not a practical problem as long as 10 or less. Such a measuring method has a correlation with the evaluation actually stored in a file or the like.

The base paper used in the present invention will be described. The pulp for base paper according to the present invention is LBKP, NBK.
Chemical pulp such as P, GP, PGW, RMP, TMP,
Mechanical pulp such as CTMP, CMP and CGP, waste paper pulp such as DIP, and wood pulp such as can be used.

In producing the base paper, various devices such as a fourdrinier paper machine, a cylinder paper machine, an on-top paper machine and a twin wire paper machine can be used.

In the ink jet recording sheet of the present invention, a size press process may be provided on the surface of the base paper, and examples of the sizing agent include starch, polyvinyl alcohol, latex, maleic anhydride size, α
-Various surface sizing agents such as olefin-based sizes and styrene-acrylic acid-based sizes, dimensional stabilizers such as ethylene-urea resins, inorganic conductive agents such as sodium chloride and potassium chloride, organic conductive agents such as dimethylaminoethyl methacrylate. Agents, surfactants, pigments, dyes, pH adjusters,
An internal additive for papermaking such as a defoaming agent, a pitch control agent and a slime control agent can be applied.

As a method of coating in the size press step, it is of course possible to use an apparatus such as a conventional size press, a gate roll size press, a metering blade type size press, a bill blade or a short dwell coater.

The base paper produced as described above may be used as it is, or a calendering device such as a machine calender, a TG calender or a soft calender may be used for the purpose of controlling flattening.

The ink jet recording sheet of the present invention is in an uncoated state or has a functional coating layer coated on the surface,
It can also be used as various recording media such as coated paper for printing, thermal recording paper, magnetic recording paper, image receiving paper for sublimation type thermal transfer recording and pressure sensitive recording paper.

[0039]

The ink jet recording sheet of the present invention is a neutral paper mainly composed of wood pulp and a filler, containing a specific amount of calcium carbonate and a specific sizing agent as the filler, and
By containing an ultraviolet-absorbing cationized polymer composed of a copolymer of a polymerizable vinyl compound having a primary ammonium salt group and a polymerizable vinyl compound having a structural unit having an ultraviolet-absorbing ability, the printing density is high and the ink It has the characteristics of excellent absorbency and light resistance of the image, and excellent yellowing resistance of the white paper portion.

The reason is that, firstly, it is considered that the use of a specific filler and sizing agent contributes to the ink absorptivity and can suppress the spread of the dots. As a result, the ink absorptivity can be reduced. And the print density can be improved. Second, the UV absorbing cationized polymer is
It is presumed that this is because the structural unit having an ultraviolet absorbing ability is stabilized by being bonded to the polymerizable vinyl compound having a quaternary ammonium salt group, without being affected by external conditions. The polymerizable vinyl compound itself having a quaternary ammonium salt group bonded thereto has a role as an adhesive in the base paper or on the surface when it is contained or coated on the base paper.
It will be firmly fixed. As a result, the inkjet recording sheet of the present invention can have the above characteristics.

On the other hand, conventionally used UV absorbers are mixed with a resin for fixing the UV absorbers and contained in the coating layer of the base paper, or mixed with pulp slurry and internally added to the base paper. Since the ultraviolet absorbent itself exists independently, it has a drawback that it migrates to the surface of the base paper or the coating layer over time depending on the external environment and loses its function.

[0042]

EXAMPLES The present invention will be described in detail below with reference to examples. The present invention is not limited to this. All parts and% in the following are by weight.

Preparation examples of the ultraviolet absorbing cationized polymer are shown below in advance. Preparation Example 1 UV absorber polymer was prepared in the same manner as in Preparation Example 1 using 30 g of 2- [2′-hydroxy-5 ′-(methacryloyloxy) phenyl] benzotriazole, 70 g of N, N-diethylaminoethyl acrylate and 100 g of ethyl cellosolve. An aqueous solution was synthesized. Subsequently, 30 g of monochloroacetic acid was added dropwise over 30 minutes, and the reaction was performed for 2 hours in a nitrogen atmosphere. After completion of the reaction, the mixture was cooled to room temperature and diluted with water to obtain an ultraviolet absorbing cationized polymer aqueous solution (solid content 20% by weight) of Preparation Example 1.

Preparation Example 2 2-hydroxy-4- (2-methacryloyloxy) ethoxybenzophenone 30 g, N-2-hydroxy-3
-Preparation Example 1 using 70 g of acryloyloxypropyl-N, N-dimethylamine and 100 g of ethyl cellosolve
An ultraviolet absorbent polymer aqueous solution was synthesized in the same manner as in.
Subsequently, 30 g of methyl chloride was added dropwise over 30 minutes, and the reaction was performed in a nitrogen atmosphere for 2 hours. After completion of the reaction, the mixture was cooled to room temperature and diluted with water to obtain an ultraviolet absorbing cationic polymer aqueous solution (solid content 20% by weight) of Preparation Example 2.

Preparation Example 3 2- [2'-hydroxy-5 '-(methacryloyloxy) phenyl] -5-chlorobenzotriazole 30
g, N, N-diethylaminoethyl acrylate 70
g and 100 g of ethyl cellosolve, an ultraviolet absorbent polymer aqueous solution was synthesized in the same manner as in Preparation Example 1. Subsequently, 30 g of benzyl chloride was added dropwise over 30 minutes, and the reaction was performed in a nitrogen atmosphere for 2 hours. After completion of the reaction, the mixture was cooled to room temperature and diluted with water to obtain an ultraviolet absorbing cationized polymer aqueous solution (solid content 20% by weight) of Preparation Example 3.

Preparation Example 4 2-hydroxy-4-methacryloyloxybenzophenone (30 g), N, N-dimethylaminopropylacrylamide (70 g) and ethyl cellosolve (100 g) were added to a separa equipped with a Dimroth, a dropping funnel, a thermometer, a nitrogen introducing tube, and a stirrer. The mixture was charged into a bull flask and the temperature was raised to 80 ° C. while introducing nitrogen from a nitrogen introducing pipe. After that, 0.1 g of azobisisobutyronitrile dissolved in a small amount of ethyl cellosolve was divided into 4 portions and added dropwise over 30 minutes. After completion of the dropping, reaction was carried out for 2 hours in a nitrogen atmosphere to synthesize an ultraviolet absorbent polymer aqueous solution. Subsequently, 30 g of diethyl sulfuric acid
Was added dropwise over 30 minutes, and the reaction was performed for 2 hours under a nitrogen atmosphere. After the reaction is complete, cool to room temperature, dilute with water,
An ultraviolet absorbing cationic polymer aqueous solution (solid content 20% by weight) of Preparation Example 4 was obtained.

Example 1 70 parts of LBKP (freezing degree 350 mlcsf) and NBKP
(Freeness 400 mlcsf) To 100 parts of wood pulp consisting of 30 parts, calcium carbonate (manufactured by Okutama Kogyo; T
P-121) 10 parts, alkyl ketene dimer size agent (manufactured by Dick Hercules; Harcon 603S) 0.
09 parts, 0.4 parts of sulfuric acid band, 0.8 parts of amphoteric starch (Oji National Co .; Cato3210), 0.02 parts of retention aid (HYMO Co .; NR-11LS) were mixed to form a pulp slurry. Was used to produce a base paper with a basis weight of 64 g / m ² using a Fourdrinier paper machine.

On this base paper, the ultraviolet absorbing cationized polymer prepared in Preparation Example 1 (adjusted to a concentration of 10% aqueous solution)
Was applied by a size press to a coating amount of 3.0 g / m ² to obtain an inkjet recording sheet of Example 1.

Example 2 In the pulp slurry formulation of Example 1, 20 parts of calcium carbonate and an alkyl ketene dimer sizing agent of 0.
An inkjet recording sheet of Example 2 was manufactured in the same manner as in Example 1 except that the amount was 15 parts.

Example 3 In the pulp slurry formulation of Example 1, the calcium carbonate was 3 parts, and the alkyl ketene dimer sizing agent was replaced with an alkenyl succinic anhydride sizing agent. Cationized polymer (10
% Aqueous solution), the inkjet recording sheet of Example 3 was prepared in the same manner as in Example 1 except that the UV absorbing cationized polymer of Preparation Example 2 (adjusted to 10% aqueous solution) was used. Manufactured.

Example 4 80 parts of LBKP (freezing degree of 400 mlcsf) and NBKP
(Freeness 480 mlcsf) To 100 parts of wood pulp consisting of 20 parts, calcium carbonate (manufactured by Okutama Kogyo; T
P-121) 17 parts, alkyl ketene dimer size agent (manufactured by Dick Hercules; Hercon 603S) 0.
A pulp slurry was prepared by mixing 10 parts, 2.0 parts of the UV-absorbing cationized polymer of Preparation Example 3, 0.5 part of a sulfuric acid band, and 0.02 part of a retention aid (manufactured by Hymo Co .; NR-11LS) into a pulp slurry. Papermaking with a Fourdrinier paper machine using
An inkjet recording sheet of Example 4 made of 4 g / m ² of base paper was obtained.

Example 5 In the pulp slurry formulation of Example 4, calcium carbonate was replaced by 20 parts, and the ultraviolet absorbing cationized polymer of Preparation Example 4 was used in place of the ultraviolet absorbing cationized polymer of Preparation Example 3. Except for the above, papermaking was performed in the same manner as in Example 4 to obtain an inkjet recording sheet of Example 5.

Comparative Example 1 An ink jet recording sheet of Comparative Example 1 was prepared by using the same base paper as that prepared in Example 1, but without size press.

Comparative Example 2 In the pulp slurry formulation of Example 1, 23 parts of calcium carbonate and 0.
An ink jet recording sheet of Comparative Example 2 was manufactured in the same manner as in Example 1 except that the amount was 18 parts.

COMPARATIVE EXAMPLE 3 2 parts of calcium carbonate and 0.1 parts of alkylketene dimer sizing agent were used in the pulp slurry of Example 1.
An inkjet recording sheet of Comparative Example 3 was manufactured in the same manner as in Example 1 except that the amount was 8 parts.

Comparative Example 4 As a UV absorber, 2- (2'-hydroxy-) was previously prepared.
5'-t-butylphenyl) benzotriazole (10 parts) was used.
0 part was mixed and dispersed by a ball mill to prepare a dispersion liquid.

Next, the same base paper as that prepared in Example 1 was coated by a size press to a coating amount of 2.5 g / m ² , to obtain an ink jet recording sheet of Comparative Example 4.

The inkjet recording sheets obtained in Examples 1 to 5 and Comparative Examples 1 to 4 were evaluated by the following evaluation methods, and the results are shown in Table 1 below. 1) Printing density Cut the inkjet recording sheet into A4 size,
After conditioning the humidity for 24 hours or more in a constant temperature and humidity chamber under the conditions of ℃ and 65% RH, two positions above and below the recording sheet using a Canon inkjet printer (BJ-10V),
Solid printing was performed at three places on the right and left, and the printed portion was measured at 12 points with a Macbeth reflection type densitometer (manufactured by Macbeth; RD-918), and this average value was used as the print density.

2) Ink absorbency: Characters are printed every 5 seconds on an inkjet recording sheet cut to A4 size, and 50 g / cm ^{2 on} sillbon paper after printing is completed.
The time (seconds) when the load starts to be pulled and the tailing starts to occur.
Was visually observed and evaluated as ink absorbency. The evaluation criteria are ○ within 5 seconds, △ within 5 to 10 seconds, and × within 1.
It was set to 0 seconds or more.

3) Feathering Using the same printer as in 1) above, a horizontal ruled line pattern and alphabet letters were printed on an A4 size cut ink jet recording sheet, and the line thickening was evaluated by visual observation. As the evaluation criteria, ◯ was good, Δ was slightly good, and X was bad.

4) Yellowing of white paper [BHT method] BHT dimer (4,4'-methylenebis-
2,6-di-tert-butylphenol) isopyl alcohol 1% solution was spotted on an inkjet recording sheet so that the solid content was 0.5 g / m ² .
L ^* a ^* before and after standing for 3 days at 20 ° C. and 65% RH
b ^* (color specification method based on CIE) is a color difference meter (CR
100: manufactured by Minolta). Then, the degree of yellowing of the white paper portion was evaluated by the difference in b ^* before and after the treatment (Δb ^* ). It should be noted that the smaller this value is, the smaller the yellowing change is.

[File Method] A polypropylene plastic file bag (A4 size) containing 1.0% by weight of commercially available BHT was cut into a square of 5 cm × 5 cm in the vicinity of the center of one side so that the coating layer surface had holes. Put it in a file bag so that it hits the file side, leave it for a month in the room, take out the sample, and color the inkjet recording sheet before and after processing L ^* a ^* b ^* (coloring method according to CIE) It was measured with a color difference meter (CR100: manufactured by Minolta). The degree of yellowing of the white paper part depends on the difference in b ^* before and after processing (△
b ^* ), and a smaller value indicates less yellowing.

5) Lightfastness of Image Regarding the lightfastness of the image, solid printing of magenta ink was performed using an ink jet printer (MJ-700V2C, manufactured by EPSON). The inkjet recording sheet after recording was used with a xenon arc fade meter, Atlas Ci-35f, and a black panel temperature of 63.
The color difference of the magenta ink color before and after light irradiation for 30 hours was measured under the environment of ° C and relative humidity of 65% RH. The color difference is
According to L ^* a ^* b ^* (color specification method based on CIE), it can be defined by the following mathematical formula 1 based on the result of measuring the color of each inkjet recording sheet before and after light irradiation. The larger the color difference, the more the color deterioration occurs. The measurement was performed using a standard light C, CR100 manufactured by Minolta. If the color difference is less than 1.0, it is almost impossible to visually recognize the color difference.

[0064]

## EQU1 ## ΔE = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 where ΔE is the color difference, ΔL ^* and Δa ^* and Δb ^* Is the difference between L ^* and a ^* and b ^* before and after light irradiation.

[0065]

[Table 1]

Evaluation: From the results in Table 1 above, the ink jet recording sheets of Examples 1 to 5 according to the present invention are excellent in print density, ink absorbency, feathering, light fastness of images, and yellowing resistance of white paper. It had the following characteristics.

On the other hand, in the ink jet recording sheet of Comparative Example 1, the base paper itself of Example 1 was used as the ink jet recording sheet, but the yellowing of the white paper portion and the light fastness of the image were poor. The inkjet recording sheet of Comparative Example 2 contained a large amount of filler and was inferior in feathering.
On the contrary, the ink jet recording sheet of Comparative Example 3 contained a small amount of the filler and was inferior in ink absorbency. In the inkjet recording sheet of Comparative Example 4, the coating liquid for size press was composed of a single ultraviolet absorber, and the ink absorbency was poor, and the yellowing of the white paper portion was also poor.

[0068]

The ink jet recording sheet of the present invention is
By using a neutral paper containing a specific amount of filler and sizing agent as a support and containing an ultraviolet-absorbing cationized polymer, the print density is high, and the ink-jet recording characteristics such as ink absorbability and It has excellent effects on light resistance and yellowing resistance of white paper.

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[Procedure amendment]

[Submission date] March 3, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction content]

Preparation examples of the ultraviolet absorbing cationized polymer are shown below in advance. Preparation Example 1 2- [2'-hydroxy-5 '-(methacryloyloxy) phenyl] benzotriazole (30 g), N, N-diethylaminoethyl acrylate (70 g), ethyl cellosolve (100 g) were added to a Dimroth, a dropping funnel, a thermometer, and nitrogen.
Put into a separable flask equipped with an element introduction tube and a stirrer
Then, while introducing nitrogen from the nitrogen introduction pipe, raise the temperature to 80 ° C.
Warmed. Then, dissolve in a small amount of ethyl cellosolve.
Divide 0.1g of zobisisobutyronitrile into 4 parts, 30 minutes
Dropped between. After dropping, react for 2 hours under nitrogen atmosphere
Then, an ultraviolet absorbent polymer aqueous solution was synthesized. Subsequently, 30 g of monochloroacetic acid was added dropwise over 30 minutes, and the reaction was performed for 2 hours in a nitrogen atmosphere. After completion of the reaction, the mixture was cooled to room temperature and diluted with water to obtain an ultraviolet absorbing cationized polymer aqueous solution (solid content 20% by weight) of Preparation Example 1.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0046

[Correction method] Change

[Correction content]

[0046] Preparation Example 4 2-hydroxy-4-methacryloyloxy benzophenone 30 g, N, N-dimethylaminopropyl acrylamide 70 g, ethyl cellosolve 100g used, the preparation
A UV absorber polymer aqueous solution was synthesized in the same manner as in Example 1 . Subsequently, 30 g of diethyl sulfuric acid was added dropwise over 30 minutes, and the reaction was performed for 2 hours under a nitrogen atmosphere. After completion of the reaction, the mixture was cooled to room temperature and diluted with water to obtain an ultraviolet absorbing cationic polymer aqueous solution (solid content 20% by weight) of Preparation Example 4.

Claims (2)

[Claims] 1. A neutral paper comprising mainly wood pulp and a filler, containing 3 to 20% by weight of calcium carbonate as a filler (relative to pulp) and an alkyl ketene dimer or alkenyl succinic anhydride as an internally added sizing agent. An inkjet recording sheet containing an ultraviolet-absorbing cationized polymer comprising a copolymer of a polymerizable vinyl compound having a quaternary ammonium salt group and a polymerizable vinyl compound having a structural unit having an ultraviolet-absorbing ability. . 2. A structural unit having an ultraviolet absorbing ability is 2-
A hydroxybenzophenone residue or a 2-hydroxybenzotriazole residue.
The inkjet recording sheet described.