JPH07224239A - Polymer fine particles for inkjet recording ink - Google Patents

Abstract

(57) [Summary] [Purpose] When recording is performed by flying as droplets discharged from the discharge orifice of the recording head, it is excellent in dryness,
To obtain polymer particles which are excellent in printing quality such as bleeding, sharpness of contour, sharpness and durability, and which are excellent in ink jet recording stability. [Structure] The surface of crosslinked polymer particles (A) obtained by polymerizing a polymerizable monomer having a crosslinkable monomer content of 10 wt% or more has a crosslinkable monomer content of 10 wt%.
(B) obtained by polymerizing less than 1 polymerizable monomer
Partially or wholly covered with and the weight ratio of (A) / (B) is 100 / 0.01 to 900.
Polymer fine particles for ink jet recording ink, characterized in that they are parts by weight.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is excellent in drying property when ink is ejected as droplets ejected from an ejection orifice of a recording head to cause bleeding, sharpness of contour, sharpness and durability. For example, the present invention relates to polymer particles capable of producing an inkjet recording ink having excellent printing quality and excellent nozzle ejection stability.

[0002]

2. Description of the Related Art Conventionally, those that have a high drying speed after printing are
There is a problem that nozzle ejection stability is deteriorated due to clogging that accompanies drying and solidification of ink, and conversely, those having good ejection stability have poor drying properties. To achieve both of these, JP-A-55-1
No. 6042, JP-A-55-29546, etc.
It has been proposed to use a dye, a specific high-boiling point water-soluble solvent (wetting agent) and water as main components in order to improve nozzle ejection stability, and various surfactants for improving quick drying property.
However, the ink penetrates too much into the paper, causing bleeding,
There were new problems such as sharpness of contour, sharpness, and durability, which deteriorated the printing quality, which was not satisfactory. On the other hand, in JP-A-3-79678, 50-30
A method of adding a 0 angstrom ultrafine particle emulsion is disclosed. Also, JP-A-54-5850
4, JP-A-60-38481, JP-A-55-139.
No. 471, JP-A-3-250069, a hydrophobic dye,
An ink jet recording ink comprising a polymer emulsion colored with a basic dye and a disperse dye is disclosed. However, in these methods, although the blurring and the sharpness of the contour are good, there is a problem that the nozzle is hard to be clogged because the film forming property of the fine particles is too good, the nozzle ejection stability is deteriorated, and the printing is blurred.

[0003]

SUMMARY OF THE INVENTION The present invention has been made against the background of the above-mentioned conventional technical problems, and is excellent in drying property and excellent in print quality such as bleeding, sharpness of contour, sharpness and durability. Further, it is an object of the present invention to provide polymer fine particles for inkjet recording ink, which can provide an inkjet recording ink excellent in nozzle ejection stability.

[0004]

Means for Solving the Problems According to the present invention, the surface of crosslinked polymer particles (A) obtained by polymerizing a polymerizable monomer having a crosslinkable monomer content of 10% by weight or more has a crosslinkable monomer content of Is partially or entirely coated with a polymer (B) obtained by polymerizing a polymerizable monomer of less than 10% by weight, and the weight ratio of (A) / (B) is 1
The present invention provides polymer fine particles for ink jet recording ink, characterized in that the amount is 00 / 0.01 to 900 parts by weight. Hereinafter, the present invention will be described in detail.

The fine polymer particles for ink jet recording ink of the present invention have a group containing a polymerizable double bond in the molecule.
The content of the crosslinkable monomer (hereinafter, simply referred to as "crosslinkable monomer") having 10 or more of the crosslinkable monomer is 10% by weight or more. Polymer (B) obtained by polymerizing a polymerizable monomer in an amount of less than 20% by weight is partially or entirely laminated, and the weight ratio of (A) / (B) is 10
The particles are 0 / 0.01 to 900 parts by weight. The content of the crosslinkable monomer in the polymerizable monomer used in the crosslinked polymer particles (A) is 10% by weight or more, preferably 15% by weight or more, more preferably 20% by weight or more. If the content of the crosslinkable monomer is less than 10% by weight, clogging of the dried and solidified ink becomes strong and the nozzle ejection stability becomes poor. Polymer (B)
The content of the crosslinkable monomer in the polymerizable monomer used in step 1 is less than 10% by weight, preferably 8% by weight or less, more preferably 5% by weight or less. The content of the crosslinkable monomer in the polymerizable monomers constituting the polymer (B) is 10
When the content is more than 5% by weight, the adhesiveness of the polymer fine particles is completely lost, the fixability of the printed ink becomes poor, and the printing durability becomes poor.

The amount of the polymer (B) laminated partially or entirely on the surface of the crosslinked polymer particles (A) is 0.01 to 900 based on 100 parts by weight of the crosslinked polymer particles (A).
The amount is preferably 10 to 900 parts by weight, more preferably 20 to 400 parts by weight. When the amount of the polymer (B) is less than 0.01 parts by weight, the printing durability is deteriorated, while when it exceeds 900 parts by weight, the nozzle ejection property is deteriorated. Further, the polymer (B) is a group having chemical reactivity or ionicity in the molecule and has a functional group (hereinafter, simply referred to as “functional group”) excluding a group containing a polymerizable double bond. In that case, the ink fixability and the printing durability can be further improved. Here, as the functional group, a carboxyl group, a hydroxyl group, an N-methylol group, a sulfone group, a maleic anhydride unit, an epoxy group, an amino group, an amide group,
It is at least one selected from reactive functional groups such as a nitrile group. Preferred functional groups are carboxyl group, hydroxyl group, amino group and amide group.

The average particle diameter of the polymer fine particles for ink jet recording ink of the present invention is 0.01 to 2 μm, preferably 0.02 to 1 μm, and more preferably 0.04 to 0.
It is 5 μm. The average particle diameter here is measured by the following method. The average particle diameter of the polymer fine particles for ink jet recording ink is measured by directly measuring 100 particles by a transmission electron micrograph (if the particles are not spherical, the long diameter and the short diameter are measured and the average value thereof is measured). Is calculated.) Is performed.

The glass transition temperature of the above polymer (B) is preferably 50 ° C. or lower, particularly 20 ° C. or lower. When the glass transition temperature of the polymer (B) is 50 ° C. or higher, the durability of printing is lowered, which is not preferable. Examples of the crosslinkable monomer used in the crosslinked polymer particles (A) and the polymerizable (B) include a non-conjugated vinyl compound represented by divinylbenzene or a polyvalent acrylate compound represented by trimethylenepropanetrimethacrylate. The following compounds having one or more copolymerizable double bonds are mentioned, and these are used alone or in combination of two or more.

Specific examples of the crosslinkable monomer include polyethylene glycol diacrylate, 1,3-butylene glycol diacrylate, 1,6-butylene glycol diacrylate, 1,6-hexanelenglycol diacrylate and neopentyl glycol diacrylate. ,
Polypropylene diacrylate, 2,2'-bis (4-
Acryloxyproproxyphenyl) propane, 2,
Diacrylate compounds such as 2'-bis (4-acryloxydiethoxyphenyl) propane, trimethylolpropane triacrylate, trimethylolethane triacrylate, triacrylate compounds such as tetramethylolmethane triacrylate, ditrimethylolpropane tetraacrylate, Tetramethylolmethane tetraacrylate, tetraacrylate compounds such as pentaerythritol tetraacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol methacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene Glycol dimethacrylate, 1,6-hexane glycol dimethacrylate, Methane compounds such as opentyl glycol dimethacrylate, dipropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 2,2-bis (4-methacryloxydiethoxyphenyl) propane, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, etc. Examples thereof include trimethacrylate compounds, methylenebisacrylamide and divinylbenzene.
Of the above, divinylbenzene, ethylene glycol dimethacrylate, or trimethylolpropane trimethacrylate is preferably used, and divinylbenzene is particularly preferable.

Among the polymerizable monomers other than the crosslinkable monomer, examples of the monomer having no functional group include the following compounds, which may be used alone or in combination of two or more.
Aromatic monovinyl compounds such as styrene, ethylvinylbenzene, α-methylstyrene, fluorostyrene, vinylpyrine, butyl acrylate, 2-ethylhexyl acrylate, β-methacryloyloxyethyl hydrogendiene phthalate, N, N′-dimethylaminoethyl acrylate, etc. Acrylic ester monomer, 2
-Methacrylic acid ester monomers such as ethylhexyl methacrylate, methoxydiethylene glycol methacrylate, methoxypolyethylene glycol methacrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, N, N'-dimethylaminoethyl methacrylate, silicon-modified monomers, macromonomers and the like. Further, conjugated double bond compounds such as butadiene and isoprene, vinyl ester compounds such as vinyl acetate, 4-methyl-1-pentene and other α-olefin compounds can be mentioned.

Among the polymerizable monomers other than the crosslinkable monomer, those having a functional group include mono- or dicarboxylic acid monomers such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, and 2-acryloyloxyethyl-2-. Hydroxyethylphthalic acid, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxyethyl methacrylate, N-methylol acrylamide, sodium styrenesulfonate, maleic anhydride,
Glycidyl acrylate, glycidyl methacrylate,
Examples thereof include amide compounds such as acrylamide, methacrylamide, and methylenebisamide; vinyl cyanide compounds such as acrylonitrile and methacrylonitrile. In the present invention, the functional group-containing monomer is contained in the monomer constituting the polymer (B) in an amount of 0.05 to 20% by weight, and preferably 0.1 to 15% by weight, of the polymer particles for inkjet recording ink. It is preferable from the viewpoint of improving the ink fixability and the printing durability. Preferred polymerizable monomers are styrene, ethyl vinyl benzene, acrylonitrile, tyl methacrylate, butyl acrylate, and functional group-containing monomers.

Preferred combinations of the polymerizable monomers constituting the crosslinkable polymer particles (A) include crosslinkable monomers such as non-conjugated vinyl compounds and polyvalent methacrylate compounds and aromatic monovinyl compounds, acrylic acid ester monomers, methacrylic acid esters. Examples thereof include a combination with a polymerizable monomer such as a monomer, and a combination of a non-conjugated divinyl compound and an aromatic monovinyl compound is particularly preferable. Further, as a preferable combination of the polymerizable monomers constituting the polymer (B), a crosslinkable monomer such as a non-conjugated vinyl compound, a polyvalent acrylate or a polyvalent methacrylate compound and an aromatic monovinyl compound, an acrylic acid ester monomer, methacrylic acid A combination of a polymerizable monomer such as an ester monomer and a monomer having a functional group can be mentioned, and a combination of a non-conjugated vinyl compound, an aromatic monovinyl compound and a di- or monocarboxylic acid is particularly preferable.

Next, a preferred method for producing the polymer fine particles for ink jet recording ink of the present invention will be described. First,
A polymerizable monomer having a content of the crosslinkable monomer of 10% by weight or more is preferably polymerized by the emulsion polymerization method to obtain crosslinked polymer particles (A). The average particle size of the crosslinked polymer particles (A) at this time is not particularly limited, and the crosslinkability is set so that the desired average particle size of the finally obtained polymer fine particles for inkjet recording ink can be obtained. The average particle size of the polymer particles (A) is appropriately determined. The average particle diameter of the crosslinked polymer particles (A) can be controlled by the amount of the emulsifier, stirring, and other known methods. In the presence of 100 parts by weight of the crosslinked polymer particles (A), the content of the crosslinkable monomer is less than 10% by weight, and preferably the content of the monomer having a functional group is 0.05 to 20% by weight. Monomer 0.0
By polymerizing 1 to 900 parts by weight, preferably by an emulsion polymerization method, the polymer (B) is appropriately laminated on the entire surface of the crosslinked polymer particles (A) or partially. In the present invention, partially coating the surface of the crosslinked polymer particles with the polymer (B) means that less than 100% of the total surface area of the crosslinked polymer particles, preferably 0.00001% or more and less than 100% of the polymer ( It shows that it coats with B).

The method of adding the polymerizable monomer in the polymerization to obtain the polymer (B) is preferably a method of adding a part or the whole amount continuously or intermittently. Regarding the method of imparting a functional group to the above polymer (B) by chemical treatment, for example, after obtaining the polymer (B) having an epoxy group, it is treated with ammonia, methylamine or the like. An amino group can be added or a sulfone group can be added by treatment with sodium hydrogen sulfite or sulfuric acid. The polymerization initiator used in the above emulsion polymerization is not particularly limited as long as it is used in ordinary emulsion polymerization and suspension polymerization, but potassium persulfate, sodium persulfate, persulfate salts such as ammonium persulfate are used. The initiator, azo-based initiator, hydrogen peroxide, organic peroxide and the like may be used alone or in combination with various reducing agents such as ascorbic acid.

In the above emulsion polymerization, a suspension protective agent or a surfactant is used in order to enhance the stability of the polymerization reaction system. Usual surfactants can be used, for example, dodecylbenzene sulfonate, dodecyl sulfate, lauryl sulfate, dialkyl sulfosuccinate, polyoxyethylene alkyl phenyl ether sulfate, polyoxyethyne aralkyl propenyl. Examples thereof include anionic surfactants such as phenyl ether sulfate and formalin condensate of naphthalenesulfonic acid. Here, examples of the salt include sodium and ammonium. Furthermore, it is also possible to use nonionic surfactants such as polyoxyethylene nonylphenyl ether, polyethylene glycol monostearate, polyoxyethylene alkylpropenyl phenyl ether, sorbitan monostearate.

Further, it is possible to use a generally known reactive emulsifier such as sodium naphthalenesulfonate alone or in combination with the above-mentioned surfactant. As a preferable suspension protector, water-soluble polymers such as polyvinyl alcohol, polyvinylpyrrolidone, carboxymethyl cellulose, sodium polyacrylate, and hydroxypropyl cellulose can be used. They are,
They may be used alone or in combination. A preferable combination is a combination of an anionic surfactant, a nonionic surfactant and a water-soluble polymer. In the production of the polymer fine particles for inkjet recording ink of the present invention, the polymerization of the crosslinked polymer particles (A) to the polymerization of the polymer (B) may be carried out in the same reaction system, or the crosslinked polymer particles (A) The polymerization and the polymer (B) may be carried out in separate reaction systems. When the polymerization of the crosslinked polymer particles (A) and the polymerization of the polymer (B) are carried out in the same reaction system, the polymerization addition rate of the crosslinked polymer particles (A) is 70.
The monomer constituting the polymer (B) may be added when the amount reaches 90% by weight, preferably 90% by weight. When the crosslinked polymer particles (A) are polymerized, it is preferable to use polystyrene particles as a seed.

The polymer fine particles for ink jet recording ink can basically be mixed with a dye (or pigment) and a medium to prepare an ink jet recording ink. Examples of dyes that can be used in the present invention include acid dyes, basic dyes, direct dyes, disperse dyes, and reactive dyes. Specifically, as the black dye, direct black # 19 (CI.35255), direct black # 154, hood black # 2 (CI.27).
755), Solvent Black # 3, Solvend Block # 22, Solvent Black # 23, and the like, and Acid Yellow # 23 (C.I. 1914) as a yellow dye.
0), Solvent Yellow # 19, Solvent Yellow # 21, Solvent Yellow # 61, Solvent Yellow # 80, etc., and Acid Red # as a magenta dye.
87 (C.I. 45380), Acid Red # 106.
(C.I. 45100), Solvent Red # 8,
Solvent Red # 49, Solvent Red # 81, Solvent Red # 82, Solvent Red # 83, Solvent Red # 84, Solvent Red # SO100, Solvent Red # 109, Solvent Red # 121, etc. (C.I.
42090), Direct Blue # 86 (C.I. 74)
180), Solvent Blue # 11, Solvent Blue # 12, Solvent Blue # 25, Solvent Blue #
36, Solvent Blue # 55, Solvent Blue # 7
3 and the like.

As the pigment, those in which ordinary organic pigments or inorganic pigments are dispersed in fine particles are used, and those in which the particle diameter of the pigment is 0.1 μm or less are preferable. If the amount of the dye or pigment added is less than 0.5% by weight of the ink jet recording ink, sufficient color tone and density cannot be obtained, and if it exceeds 10% by weight, clogging is likely to occur. % Is preferred. Further, as the medium, water or other aqueous medium, for example, ethylene glycol, prolene glycol butylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol 200, 400, 600, 150.
0, glycerin, n-methylolprolidone, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol diethyl ether and the like.
These aqueous media are usually added in an amount of 10 to 99% by weight of the inkjet recording ink. The polymer fine particles for an inkjet recording ink of the present invention have a total solid content of the inkjet recording ink of 5 to 90% by weight, preferably 10 to 7.
It is added so as to be 0% by weight. In addition to the above, the ink jet recording ink further includes a water-soluble polymer, a polymer emulsion, a surfactant, a pH adjusting agent, an antiseptic / antifungal agent,
A rust preventive agent, a chelating agent, an ultraviolet absorber, an infrared absorber and the like can be added.

[0019]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited thereto. In the following description, "part" means "part by weight" and "%" means "% by weight". Example 1 As a first step, divinylbenzene (commercial product, purity 55
%, The remaining 40% is ethyl vinyl benzene, the remaining 5%
Is diethylbenzene) 35 parts, styrene 55 parts, acrylic acid 10 parts, sodium dodecylbenzenesulfonate 1
5 parts, ion-exchanged water 900 parts and sodium persulfate 1
One part was placed in a reaction vessel and polymerized under stirring at 80 ° C. for 1 hour. Then, subsequently, as a second step, 30 parts of methyl methacrylate, 60 parts of n-butyl acrylate, 9 parts of methacrylic acid and 1 part of ethylene glycol methacrylate.
Then, a mixed monomer consisting of parts was continuously added for 3 hours to complete the polymerization to obtain polymer fine particles a for inkjet recording ink. The average particle diameter of the obtained polymer fine particles a for inkjet recording ink (hereinafter referred to as particles a) was measured and found to be 0.05 μm. An ink jet recording ink having the following composition was prepared using the obtained polymer fine particles a. Direct black # 19 3% Glycerin 4% Polymer fine particles a 10% Water 83% The above components were thoroughly mixed and stirred in a container, and filtered with a membrane filter having a pore size of 0.5 μm to prepare an inkjet recording ink.

Using the ink jet recording ink thus obtained, printing was carried out using a commercially available ink jet printer, and the following evaluations were carried out. The results are shown in Table 1. As the evaluation paper, PPC paper having a size of 17 seconds and stock form paper having a size of 16 seconds were used. (1) Drying speed After printing for 5 seconds, the printed portion was rubbed with a finger and the presence or absence of deviation of the ink was observed. ◯: No misalignment was found between the two types of paper. X: A slight deviation is recognized on either of the two types of paper. (2) Sharpness After printing, bleeding of the screen and uneven density were visually observed. ◯: Both types of paper bleed at all and no density unevenness is observed. X: Bleeding and density unevenness are recognized even on either of the two types of paper. (3) Jetting stability After the ink was filled in the printer and left for 3 months, reprinting was performed to evaluate whether or not printing could be performed smoothly. ◯: Printing was successful. X: Clogging was observed in the nozzle and printing was impossible.

Comparative Example 1 Polymeric particles b having an average particle size of 0.04 μm were produced by carrying out only the first step in Example 1. An inkjet recording ink was prepared in the same manner as in Example 1 using the obtained polymer fine particles b, and the drying rate, sharpness and jetting stability were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 2 Divinylbenzene 5 in the first step in Example 1
Polymer fine particles c having an average particle diameter of 0.06 μm were produced in the same manner as in Example 1 except that 5 parts, 10 parts of acrylic acid and 35 parts of styrene were replaced with 90 parts of styrene and 10 parts of acrylic acid. An inkjet recording ink was prepared in the same manner as in Example 1 using the obtained polymer fine particles b, and the drying rate, sharpness and jetting stability were evaluated in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 3 An ink jet recording ink was prepared in the same manner as in Example 1 except that no polymer fine particles were used.
The sharpness and jetting stability were evaluated in the same manner as in Example 1.
The results are shown in Table 1.

[0024]

[Table 1]

[0025]

INDUSTRIAL APPLICABILITY The ink jet recording ink using the polymer fine particles for ink jet recording ink of the present invention is excellent in quick-drying property, is excellent in print quality such as bleeding, sharpness of contour, sharpness and durability, and further has a nozzle Excellent discharge stability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Ito 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd.

Claims (1)

[Claims] 1. The surface of crosslinked polymer particles (A) obtained by polymerizing a polymerizable monomer having a crosslinkable monomer content of 10% by weight or more has a polymerizable content of the crosslinkable monomer of less than 10% by weight. The polymer (B) obtained by polymerizing the monomers is partially or entirely coated, and the weight ratio of (A) / (B) is 100 / 0.01 to 90.
0 parts by weight of polymer fine particles for ink jet recording ink.