JP2007291306A - Additive for inkjet recording sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an additive for an inkjet recording sheet excellent in high density color developing properties. <P>SOLUTION: This additive for inkjet recording sheet comprises an emulsified product obtained by copolymerizing (A) butyl methacrylate of 20-80 mol%, (B) acrylic amide of 20-80 mol% and (C) a copolymerizable monomer of 0-20 mol% other than the 2 components described above, as monomer components, wherein A+B+C is 100 mol%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an additive for inkjet recording paper. More specifically, the present invention relates to an additive for ink jet recording paper that develops high density color developability when printing with an ink jet printer.

In recent years, personal computers and ink jet printers have become quite popular in general households, and many high-performance digital cameras have also become popular. As a result, it has become possible to easily print high-quality images such as photographs.

Further, from these users, it is desired to further improve the color developability of an image printed on an ink jet recording paper by an ink jet printer. Conventionally, ink jet recording paper coating methods are roughly classified into pigment-coated paper and non-coated paper. The former pigment-coated paper is generally called (matte paper, glossy paper), and the ink receiving layer is formed by coating the base paper with a coating liquid composed of a porous pigment such as silica or alumina, a binder or the like. For this reason, the density color development can be improved, but it is not sufficient. Further, since many expensive pigments and binders are used, there is a disadvantage that the cost is high. On the other hand, non-coated paper is generally called plain paper, which is obtained by subjecting a coating liquid made of inexpensive starch or the like without using a pigment to a size press process, and is very inexpensive. However, since the ink receiving layer is paper itself, there is a drawback that it is difficult to develop high density color development of printed ink.

Conventionally, as a color development improving method, a solution obtained by dissolving a water absorbent resin such as a reaction product of cellulose ether and N-methylolacrylamide and a polymer binder such as polymethyl methacrylate in a solvent such as methyl ethyl ketone. It is coated on paper. (See Patent Document 1)

Moreover, the thing which used the emulsion polymer of methyl methacrylate as an active ingredient, or the thing which used the emulsion copolymer of methyl methacrylate and (meth) acrylamide as an active ingredient is disclosed. (See Patent Document 2)
However, in Patent Document 1, the color developability is not yet sufficient, and further, since an organic solvent is used, there is a problem that the working environment is deteriorated. Further, although Patent Document 2 shows some improvement in color developability, it is still not sufficient.
JP-A-57-173194 JP 2002-46345 A

Problems to be solved by the invention

An object of the present invention is to develop an additive that is more excellent in density color development than ever in inkjet recording paper.

Means for solving the problem

In order to solve the above problems, the present inventor considered that high-density color development can be obtained by suppressing the permeability of ink to paper, and as a result of careful examination, (A) methacrylic acid of the present invention was obtained. 20-80 mol% of butyl acid, 20-80 mol% of (B) acrylamide, and (C) an emulsion obtained by copolymerizing 0-20 mol% of a copolymerizable monomer other than the above two components (however, The present invention has been completed by finding an excellent color density at A + B + C = 100 mol%.

That is, the present invention provides a monomer component comprising A) 20-80 mol% butyl methacrylate, (B) 20-80 mol% acrylamide, and (C) a monomer copolymerizable with the above two components. It is an additive for inkjet recording paper comprising an emulsion copolymerized at 0 to 20 mol% (provided that A + B + C = 100 mol%).

As the monomer component of the present invention, (A) 20-80 mol% butyl methacrylate, (B) 20-80 mol% acrylamide, It is an additive for ink jet recording paper comprising an emulsion copolymerized at 20 mol% (provided that A + B + C = 100 mol%). These additives for ink jet recording paper can be used by coating or internally adding to the ink jet recording paper, respectively.

As described above, in the present invention, as a monomer component, A) 20 to 80 mol% of butyl methacrylate, (B) 20 to 80 mol% of acrylamide, and (C) other than the above two components as a monomer component An emulsion obtained by copolymerizing a nonionic or anionic monomer copolymerizable at 0 to 20 mol% (provided that A + B + C = 100 mol%) is necessary to improve density color development. If the content of butyl methacrylate is less than 20 mol% or more than 80 mol%, the density color developability is not improved. On the other hand, if the amount of acrylamide is 20 mol% or less, the stability of the emulsion is poor and the density color development is also poor. Further, as the copolymerizable monomer other than butyl methacrylate and acrylamide, any of nonionic, anionic and cationic monomers can be used, and nonionic and anionic monomers are particularly preferable. . These copolymerizable monomers can be contained in a proportion of 0 to 20 mol%. However, if it exceeds 20 mol%, the effect of improving density color development cannot be obtained. The detailed mechanism of this density coloring improvement is not clear, but it is more hydrophobic than methyl methacrylate, and in addition, the refractive index of butyl methacrylate is higher than that of methyl methacrylate and the refractive index of this polymer is higher. It is thought that the density color development is specifically improved. That is, the present invention provides a monomer component comprising A) 20-80 mol% butyl methacrylate, (B) 20-80 mol% acrylamide, and (C) a monomer copolymerizable with the above two components. An additive for inkjet recording paper, which is an emulsion copolymerized at 0 to 20 mol% (provided that A + B + C = 100 mol%).

Examples of copolymerizable anionic monomers other than butyl methacrylate and acrylamide that can be used in the present invention include monocarboxylic acids such as (meth) acrylic acid, crotonic acid, and (meth) allylcarboxylic acid, and maleic acid. Dicarboxylic acids such as fumaric acid, itaconic acid and muconic acid, organic sulfonic acids such as vinyl sulfonic acid, styrene sulfonic acid, acrylamide 2-methylpropyl sulfonic acid, (meth) allyl sulfonic acid, or sodium salts of these various organic acids And alkali metal salts such as potassium salts. Nonionic monomers include, for example, acrylic acid esters (1 to 18 carbon atoms), ethyl methacrylate, propyl methacrylate, methacrylic acid esters (5 to 18 carbon atoms), methacrylamide, t-butylacrylamide, and styrene. , Hydroxymethyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 2-ethylhexyl methacrylate, vinyl chloride, glycidyl (meth) acrylate, methacrylic acid Examples include allyl, cyclohexyl methacrylate, and benzyl methacrylate.

Catalysts for initiating the reaction are peroxides such as ammonium persulfate, potassium persulfate, sodium persulfate, t-butyl hydroperoxide, 2,2′-azobis (2-amidinopropane) hydrochloride, 2,2 '-Azobis [2- (2-imidazolin-2-yl) propane] sulfate, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] hydrochloride, 2,2'-azobis [ 2- (5-methyl-2-imidazolin-2-yl) propane] hydrochloride, 2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] hydrochloride, etc. A general catalyst such as an azo catalyst such as hydrogen peroxide-iron ion (II), a redox catalyst such as benzoyl peroxide-dimethylaniline can be used.

As the polymerization method, general radical polymerization methods such as dispersion polymerization, suspension polymerization, and emulsion polymerization are used.

Any nonionic, anionic, cationic active agent, nonionic, anionic or cationic polymer can be used if necessary, but in particular, nonionic, anionic active agent, nonionic, anionic It is preferable to use a polymer.

While the reaction temperature varies depending on the catalyst used, the reaction is carried out at 10 ° C to 100 ° C, more preferably 40 ° C to 80 ° C.

A detailed synthesis method of the copolymer will be described later as a synthesis example.

Detailed methods for coating the paper surface will be described later in Examples and Comparative Examples.

Synthesis examples and examples of the present invention will be described below, but it is needless to say that the examples are illustrative and the present invention is not limited thereto.

Synthesis example 1
Add 277.0 g of water, 102.86 g of n-butyl methacrylate, and 17.14 g of acrylamide to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1300 mPa · s was obtained.

Synthesis example 2
Add 277.0 g of water, 80 g of n-butyl methacrylate, and 40 g of acrylamide to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1400 mPa · s was obtained.

Synthesis example 3
To a 500 ml separable flask, add 277.0 g of water, 48 g of n-butyl methacrylate and 72 g of acrylamide, and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1500 mPa · s was obtained.

Synthesis example 4
To a 500 ml separable flask, add 277.0 g of water, 53.73 g of n-butyl methacrylate, 59.08 g of acrylamide, and 8.07 g of butyl acrylate, and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. An opalescent liquid of 2200 mPa · s was obtained.

Synthesis example 5
In a 500 ml separable flask, add 277.0 g of water, 50.39 g of n-butyl methacrylate, 54.59 g of aquaacrylamide, and 15.03 g of lauryl methacrylate, and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. An opalescent liquid of 2100 mPa · s was obtained.

Synthesis Example 6
To a 500 ml separable flask, add 277.0 g of water, 54.41 g of n-butyl methacrylate, 58.95 g of acrylamide, and 6.64 g of styrene, and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1800 mPa · s was obtained.

Synthesis example 7
Add 277.0 g of water, 53.67 g of n-butyl methacrylate, 58.14 g of acrylamide, and 8.19 g of 2-hydroxyethyl methacrylate to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 2000 mPa · s was obtained.

Synthesis example 8
Add 276.77 g of water, 51.82 g of n-butyl methacrylate, 56.14 g of acrylamide, 12.04 g of 2-ethylhexyl methacrylate, and 0.23 g of sodium methallyl sulfonate to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1800 mPa · s was obtained.

Synthesis Example 9
Add 277.0 g of water, 54.94 g of n-butyl methacrylate, 59.52 g of acrylamide, and 5.54 g of methacrylic acid to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. An opalescent liquid of 2100 mPa · s was obtained.

Comparative Synthesis Example 1
Add 273.6 g of water, 120.00 g of methyl methacrylate, and 2.4 g of sodium laurylbenzenesulfonate to a 500 ml separable flask and stir well. While adding 4.0 g of 1% aqueous potassium persulfate as a catalyst while replacing the inside of the reaction system with nitrogen, water was added to the milky white liquid obtained by reacting at 80 ° C. for 7 hours to adjust the polymer concentration to 30%. A milky white liquid of 120 mPa · s was obtained.

Comparative Synthesis Example 2
To a 500 ml separable flask, add 276.0 g of water, 95.95 g of methyl methacrylate, and 24.05 g of acrylamide, and stir well. While adding 4.0 g of 1% aqueous potassium persulfate as a catalyst while replacing the inside of the reaction system with nitrogen, water was added to the milky white liquid obtained by reacting at 80 ° C. for 7 hours to adjust the polymer concentration to 30%. A milky white liquid of 400 mPa · s was obtained.

Comparative Synthesis Example 3
To a 500 ml separable flask, add 276.0 g of water, 58.07 g of methyl methacrylate, and 61.93 g of acrylamide, and stir well. While adding 4.0 g of 1% aqueous potassium persulfate as a catalyst while replacing the inside of the reaction system with nitrogen, water was added to the milky white liquid obtained by reacting at 80 ° C. for 7 hours to adjust the polymer concentration to 30%. A milky white liquid of 630 mPa · s was obtained.

Comparative Synthesis Example 4
To a 500 ml separable flask, add 279.0 g of water, 21.82 g of n-butyl methacrylate and 98.18 g of acrylamide, and stir well. 1.0 g of 1% potassium persulfate aqueous solution was added as a catalyst while replacing the inside of the reaction system with nitrogen, and the polymer concentration was adjusted to 30% by adding water to the milky white liquid obtained by reacting at 80 ° C. for 8 hours. A milky white liquid of 440 mPa · s was obtained.

Comparative Synthesis Example 5
Add 277 g of water, 113.68 g of n-butyl methacrylate, and 6.32 g of acrylamide to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1700 mPa · s was obtained.

Comparative Synthesis Example 6
To a 500 ml separable flask, add 277.0 g of water, 34.27 g of n-butyl methacrylate, 47.12 g of acrylamide, and 38.62 butyl acrylate, and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1800 mPa · s was obtained.

Comparative Synthesis Example 7
To a 500 ml separable flask, add 277.0 g of water, 26.02 g of n-butyl methacrylate, 35.78 g of acrylamide, and 58.2 g of lauryl methacrylate, and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1900 mPa · s was obtained.

Comparative Synthesis Example 8
Add 277.0 g of water, 36.47 g of n-butyl methacrylate, 50.14 g of acrylamide, and 33.39 g of styrene to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 2000 mPa · s was obtained.

Comparative Synthesis Example 9
To a 500 ml separable flask, add 277.0 g of water, 34.09 g of n-butyl methacrylate, 46.88 g of acrylamide, and 39.03 g of 2-hydroxyethyl methacrylate, and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 2000 mPa · s was obtained.

Comparative Synthesis Example 10
Add 277.0 g of water, 29.14 g of n-butyl methacrylate, 40.07 g of acrylamide, and 50.79 g of 2-ethylhexyl methacrylate to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. An opalescent liquid of 2200 mPa · s was obtained.

Comparative Synthesis Example 11
Add 277.0 g of water, 38.32 g of n-butyl methacrylate, 52.68 g of acrylamide, and 29 g of methacrylic acid to a 500 ml separable flask and stir well. While replacing the inside of the reaction system with nitrogen, 3.0 g of 1% potassium persulfate aqueous solution was added as a catalyst, and water was added to the milky white liquid obtained by reacting at 80 ° C. for 6 hours to adjust the polymer concentration to 30%. A milky white liquid of 1800 mPa · s was obtained.

In addition, Table 1 shows mol% of the monomer composition used in Synthesis Examples and Comparative Synthesis Examples.

Example 1
58.4% by weight of water, 10.0% by weight of silica, 25.0% by weight of 12% aqueous solution of PVA-120 (Kuraray) and 6.6% by weight of the polymer described in Synthesis Example 1 (2.0% by weight in terms of solid content) %) Was applied to paper with a bar coater so that the coating amount was about 8 g / m ² and dried at 110 ° C. The coated paper was printed with an inkjet printer PM-G800 (manufactured by Seiko Epson Corporation), and a performance test was performed. The performance test will be described in detail later.

Example 2
A coated paper was prepared in the same manner as in Example 1 except that the polymer described in Synthesis Example 2 was used instead of the polymer of Synthesis Example 1 described in Example 1, and a performance test was performed.

Example 3
A coated paper was prepared in the same manner as in Example 1 except that the polymer described in Synthesis Example 3 was used instead of the polymer of Synthesis Example 1 described in Example 1, and a performance test was performed.

Example 4
The same procedure as in Example 1 was performed except that the polymer described in Synthesis Example 4 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Example 5
The same procedure as in Example 1 was performed except that the polymer described in Synthesis Example 5 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Example 6
The same procedure as in Example 1 was performed except that the polymer described in Synthesis Example 6 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Example 7
The same procedure as in Example 1 was conducted except that the polymer described in Synthesis Example 7 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Example 8
The same procedure as in Example 1 was performed except that the polymer described in Synthesis Example 8 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Example 9
The same procedure as in Example 1 was performed except that the polymer described in Synthesis Example 9 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 1 (no additive)
Apply a coating solution containing 65% water, 10.0% silica, and 25.0% 12% aqueous solution of PVA-120 (Kuraray) to a paper so that the coating amount is about 8 g / m ^2. Treated with a coater and dried at 110 ° C. The coated paper was printed with an inkjet printer PM-G800 (manufactured by Seiko Epson Corporation), and a performance test was performed. The performance test will be described in detail later.

Comparative Example 2
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 1 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 3
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 2 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 4
The same procedure as in Example 1 was conducted except that the polymer described in Comparative Synthesis Example 3 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 5
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 4 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 6
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 5 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 7
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 6 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 8
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 7 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 9
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 8 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 10
The same procedure as in Example 1 was conducted except that the polymer described in Comparative Synthesis Example 9 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 11
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 10 was used instead of the polymer of Synthesis Example 1 described in Example 1.

Comparative Example 12
The same procedure as in Example 1 was performed except that the polymer described in Comparative Synthesis Example 11 was used instead of the polymer of Synthesis Example 1 described in Example 1.

The performance test was a print density test. The test method will be described in detail.

The printing density test was performed by printing solid black, yellow, magenta, and cyan on each recording paper of Examples 1 to 10 and Comparative Examples 1 to 10 using an inkjet printer PM-G800 (manufactured by Seiko Epson Corporation). The image density after printing was measured with a Macbeth densitometer (RD-19), and the image density coloring property of each recording paper was evaluated.

Table 2 shows the test results of Examples 1 to 10 and Comparative Examples 1 to 10.

Symbols in Table 2 indicate evaluation of density color development. Evaluation criteria are as follows: Evaluation of density color developability A: Color developability improved by 0.1 or more than Comparative Example 1 (no addition).
○: 0.09 to 0.06 color developability improved from Comparative Example 1 (no addition).
Δ: 0.05 to 0.02 color development improved from Comparative Example 1 (no addition) ×: 0 to 0.01 color development improved from Comparative Example 1 (no addition).

From the results in Table 2, it is clear that the use of an additive comprising the copolymer of the present invention provides high density color development of images printed on coated paper and inkjet recording paper. It can also be used in non-coated paper.

The invention's effect

When the copolymer of the present invention is used as an additive for ink jet recording paper, high color density can be obtained.

Claims (1)

As monomer components, A) 20 to 80 mol% of butyl methacrylate, (B) 20 to 80 mol% of acrylamide, and (C) 0 to 20 mol% of a copolymerizable monomer other than the above two components. An additive for ink jet recording paper for coated paper, comprising an emulsion copolymerized with (provided that A + B + C = 100 mol%).