JPH06100810A - Aqueous pigment ink, inkjet recording method and inkjet recording apparatus using the same - Google Patents

Abstract

(57) [Summary] [Purpose] The printed matter has excellent fastness and no scratching problems.
(EN) Provided are a water-based pigment ink for inkjet recording, which can always perform stable ejection even when the driving condition is changed or is used for a long time, an inkjet recording method using the same, and an inkjet recording apparatus. A water-soluble resin of a water-based pigment ink for inkjet recording is a graft copolymer composed of a hydrophilic part and a hydrophobic part, and the weight ratio of both is in the range of 20:80 to 80:20, and The number average molecular weight of the copolymer is 1000 to 1
0000, weight average molecular weight 1500 to 200
Water-based pigment ink containing a polymer compound in the range of 00,
Also provided are an inkjet recording method and an inkjet recording apparatus using the ink.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-soluble resin for dispersing a pigment, an aqueous pigment ink containing the resin, and a recording liquid suitable for use in an ink jet printer, and further recording using the recording liquid. The present invention relates to an ink jet recording method for ejecting a recording liquid from an orifice of a head by the action of thermal energy to perform recording on a recording paper, and an inkjet recording device.

[0002]

[Prior art]

(Aqueous pigment ink for stationery) The present invention relates to an aqueous pigment ink made of a novel water-soluble resin, an inkjet recording method using the same, and an inkjet recording apparatus.
In general, water-based pigment inks have been widely used as writing instrument inks having good water resistance. In order to put water-based pigment inks for stationery into practical use, the main technical problems were dispersion stability in writing instruments, outflow, prevention of ink solidification at the pen tip, and prevention of abrasion of ballpoint pen balls.

As an example of studying dispersion stability, prevention of solidification of ink at a pen tip, and prevention of abrasion of balls of a ballpoint pen for practical use of an aqueous pigment ink, Japanese Patent Laid-Open No. 58-80 is cited.
No. 368, No. 61-200182, No. 61-2477
No. 74, No. 61-272278, No. 62-568,
JP-A Nos. 62-101671, 62-101672, JP-A 1-249869, 1-249869, and 1-301760 can be cited.

(Aqueous Pigment Ink for Printer) As these problems have been overcome and related products have been developed, attempts have been made to apply the aqueous pigment ink to a printer. However, when the conventional water-based pigment ink for stationery is mounted on a recording device such as an ink jet printer and used, there are various new problems, and in recent years, considerable proposals have been made as solutions to them.

As an ink jet ink using an aqueous pigment ink, a pigment ink using a specific water-soluble solvent and a polymer dispersant is disclosed in JP-A-56-147859 and JP-A-56-147860. Is disclosed in.
Further, JP-A-4-57859 and JP-A-4-57860 each propose an example of an ink in which a pigment and a dye are used in combination.

The problems required when the water-based pigment ink is mounted in the ink jet recording apparatus are (1) high stability of ink physical properties in the recording apparatus (2) stable droplet forming ability according to the principle of ejection (3) It is difficult for the ink to dry on the surface of the nozzle, and even if the ink is dried and the viscosity increases, it has the recoverability to clean the surface of the nozzle.

The above-mentioned (1) is a common problem with the water-based pigment ink for stationery, but it is a difficult problem because the required level is high and there are many kinds of parts in contact. In the case of (2), when used in an ink jet recording apparatus of a system in which a recording liquid is ejected by the action of thermal energy to perform recording, when a pulse is applied to ink, the heat causes a deposit on the thin film resistor, There is a special difficulty that non-ejection occurs because the ink is not completely bubbled and the ejection of the droplet cannot respond to the applied pulse. Since the conventional stationery inks do not satisfy these performances, various inconveniences as described above inevitably occur. (3) is a common problem when applied to an inkjet device.

In the recording head of the ink jet recording apparatus, the physical properties of the surface around the ejection port are extremely important for constantly and stably ejecting the recording liquid from the ejection port. That is, when the recording liquid flows around the outer surface of the ejection port when the recording head is used and a liquid pool occurs even in a part around the ejection port, when the recording liquid is ejected from the ejection port, the flight direction is normal. It will come off from the direction of (predetermined direction),
Good recording becomes difficult.

Furthermore, when the entire circumference of the discharge port is covered with the recording liquid film, a so-called splash phenomenon occurs,
Scattering of the recording liquid occurs, and stable recording becomes extremely difficult. Alternatively, when the liquid pool covering the ejection port becomes large, it becomes even impossible to eject liquid droplets from the recording head.

In order to solve such a drawback, it has been proposed as a solution to treat the outer surface surrounding the discharge port with a silicone resin or a fluorine resin to make it water-repellent or oil-repellent. For example, as described in JP-A-64-31642, a cured film of a polymerization-curable coating film-forming composition mainly composed of a fluorine-based polymer and a specific polymerization-curable monomer and / or oligomer. Many methods of coating have been reported.

However, when a long-term printing durability test is carried out using a conventional water-based pigment ink, even if the liquid-repellent treatment is performed on the peripheral portion of the ejection port as described above, the water-based pigment ink on the peripheral portion of the ejection port is Occurrence of liquid pool was observed. Such a problem does not occur in the aqueous dye ink. As a result of analyzing the factors of these various problems in discharge performance, it was found that the structure of the dispersant polymer as a surfactant is an important factor.

There are various dispersants used in water-based pigment inks for recording apparatuses that have been proposed in the past. Examples of such dispersants are disclosed in JP-A-56-147863 and JP-A-56-147863.
No. 147868, No. 56-157470, No. 61-2
No. 00182, No. 60-223074, No. 60-22
The substances disclosed in JP-A No. 3075 and JP-A-4-18461 can be mentioned.

The dispersant polymer disclosed in the above-mentioned prior art is considered to have at least a property as a polymer surfactant. However, it has been found that the above-mentioned various problems cannot be solved only by using these substances.

[0014]

The cause is that the dispersant polymer disclosed in the prior art has the same hydrophobic monomer and hydrophilic or alkali-soluble property as used in aqueous printing inks and coatings. The monomer is only a polymer compound obtained by random copolymerization. Also, their molecular weight was relatively high. However, it has become clear that there are still various problems in using the recording liquid by mounting it on a recording device of an actual product.

The present invention solves these problems and is excellent in long-term storage stability. At the same time, it is possible to always perform stable ejection even when the driving conditions are changed and the ink is used for a long time. It is an object of the present invention to provide an aqueous pigment ink for inkjet recording, which realizes prevention of solidification, an inkjet recording method using the same, and an inkjet recording apparatus.

[0016]

[Means and Actions for Solving the Problems] The role of the dispersant as a polymer surfactant is to have particles in a crystalline state or a non-crystalline state because it has few functional groups on the surface and low solubility. It is to reduce the interfacial tension with the aqueous medium while making the pigment particles as fine particles, and to create a stable state without agglomeration.

The stabilizing action is said to have both an interfacial electrochemical action (electrical repulsion due to the zeta potential) and a steric action (thermodynamic stabilization against approach of particles). For any reason, it is ideal that the hydrophobic polymer particle adsorbs the hydrophobic polymer segment on the side, while the outside of the particle that contacts the aqueous medium is surrounded by a layer of dissociated carboxyl group anions. It is believed that

The inner hydrophobic segment needs an intermolecular attractive force that has a large surface area and is easily adsorbed on the surface of the active pigment particle. Also, morphological familiarity is required but mobility is not required, and the aromatic nucleus is required. Suitable are organic pigments having polynuclear aromatic nuclei, or styrene derivatives, acrylates, etc. as anchors to carbon black.

On the other hand, as the outer segment, an acrylic acid and / or a hydroxyl group-containing monomer which is hydrophilic and gives an electric repulsive force is suitable. Further, in order to prevent aggregation of particles, it is desirable that the hydrophilic segment has mobility (degree of freedom) in which it is easily dissolved in a medium solvent. However, if these monomers are present in the chain at random relative to each other like the dispersant of the prior art, the respective functions have a negative effect on the contrary. The essential cause of the loss of stability is thought to be here in the first place.

Functions such as prevention of drying on the surface of the nozzle, non-adhesiveness with the water-repellent surface, re-dissolution to the medium, hydrophilicity of the particle surface, ionic electrification, and degree of freedom of segment for re-dissolution, etc. It is thought that it works effectively by.

That is, by taking the following concrete means according to the present invention, the above-mentioned various problems are solved, the long-term storage stability is excellent, and at the same time, stable ejection is always achieved even when the driving conditions are changed and the device is used for a long time. In addition, it is possible to provide an ink jet recording liquid in which solidification of ink at the head tip is eliminated.

The present invention provides a water-based pigment ink for ink jet recording containing a pigment, a water-soluble resin, a hydrophilic organic solvent and water, wherein the water-soluble resin is (1) (meth).
Hydrophilic polymerization chain portion containing 80 mol% or more of a monomer selected from the group consisting of acrylic acid, maleic acid and (meth) acrylic acid hydroxyalkyl ester, and styrenes and (meth) acrylic acid alkyl ester A graft copolymer comprising a hydrophobic polymerization chain part containing 80 mol% or more of a monomer selected from the group consisting of: (2) a hydrophilic polymerization chain part of the copolymer; The weight ratio of the polymerized chain portion is 20:80 to 80:
20, and (3) a high molecular compound in which the number average molecular weight of the copolymer is in the range of 1,000 to 10,000 and the weight average molecular weight is in the range of 1,500 to 20,000. It is a water-soluble resin of a water-based pigment ink for inkjet recording.

Further, according to the present invention, the water-based pigment ink contains the water-soluble resin, and by using such a recording liquid, ejection energy corresponding to a recording signal is applied to the recording liquid. Thus, the inkjet recording method and the inkjet recording apparatus are characterized in that recording is performed by ejecting the recording liquid as droplets from the fine holes. Hereinafter, the present invention will be described in detail.

(Synthesis of Graft Copolymer) In order to synthesize the graft copolymer of the present invention, a macromonomer is used because it has a relatively low molecular weight as a dispersant and a polar monomer may be introduced into the side chain. Method or ionic polymerization method is used. As the graft copolymerization method, a macromonomer method, an ionic polymerization method, a chain transfer method, a method of polymerizing a different monomer by forming an active site in a polymer by radiation, a method of bonding a prepolymer having a telechelic functional group, etc. Is conventionally known.

However, the macromonomer method is most suitable for synthesizing a polymer having a high surface activity and a low molecular weight as in the present invention. The reason is, especially used for pigment dispersion,
In order to have excellent adsorptivity to the pigment surface and to enable stable dispersion in an aqueous medium, it is necessary that the degree of polymerization of hydrophobic and hydrophilic polymerization chain moieties and the manner of connection can be structurally controlled. Because there is.

A method for synthesizing a macromonomer is described in Kaw.
Although various techniques are described in the review article by Akami et al. (Kagaku No. 37, No. 8, 1982), three methods for synthesizing the copolymer of the present invention will be described below. The polymerization method is not limited to these.

(Synthesis of Hydrophobic Macromonomer) Styrenes and / or (meth) acrylic esters are solution polymerized with thioglycolic acid as a chain transfer agent and azobisisobutyronitrile as a polymerization initiator, An oligomer having a terminal carboxyl group of a chain transfer agent is obtained.

Then, this oligomer is reacted with a glycidyl group-containing acrylic monomer such as glycidyl (meth) acrylate using a quaternized alkylammonium salt as a catalyst to purify and remove an excess glycidyl group-containing monomer. Is a vinylated oligomer. A method for producing a graft copolymer using such a chain transfer agent is described in J. Oil Color Chem. Tech. ，
34, 342 (1971) (FA Waite) and the like.

(Synthesis of Macromonomer Composed of Hydrophilic Monomer) Since a hydrophilic monomer cannot be directly subjected to living anionic polymerization, the hydrophilic group is protected in advance by esterification, alkyl etherification, silyl etherification, etc. Living polymerization is performed later. That is, in the case of a hydroxyl group-containing monomer, trimethylsilyl chloride is reacted to form trimethylsilyl ether. The produced monomer was treated with sodium naphthalene, n-butyllithium, sec-butyllithium and t in THF at -78 ° C.
A living oligomer is obtained by polymerizing with a usual anion initiator such as ert-butyllithium or 1,1-bis (trimethylsiloxy) -2-methylpropane.

The resulting oligomer is reacted with a vinyl halide monomer such as (meth) acrylic acid chloride or with an alkylene oxide, and then with a vinyl halide monomer to give a vinyl terminal. To be a modified oligomer. Next, a hydrolysis deprotecting group treatment is carried out under mildly acidic conditions to obtain a macromonomer having a hydroxyl group as a side chain.

In the case of a carboxyl group, a protection method such as alkyl esterification, alkylsilyl esterification, oxazoline cyclization and the like is taken. For example, in the case of methacrylic acid,
Then, trimethylsilyl methacrylate is used, and thereafter, polymerization and deprotection treatment are similarly performed to obtain a macromonomer having a carboxyl group as a side chain.

(Synthesis of hydrophilic group-containing macromonomer)
By using a carboxyl group-containing polymerization initiator such as 4,4'-azobis-4-cyanovaleric acid to polymerize a hydrophilic monomer in the presence of an aqueous solvent, an oligomer having a carboxyl group at the terminal can be obtained. By reacting this with glycidyl (meth) acrylate, 2-methylglycidyl (meth) acrylate, allyl glycidyl ether, allyl-2-methyl glycidyl ether, etc., a macromonomer having a vinyl group at the terminal is obtained.

Examples of (meth) acrylic acid hydroxyesters used in the present invention include hydroxyethyl (meth) acrylate and hydroxypropyl (meth).
Acrylate, hydroxybutyl (meth) acrylate, diethylene glycol, triethylene glycol,
Examples thereof include mono (meth) acrylic acid esters such as polyethylene glycol, and (meth) acrylic acid monoesters of polyhydric alcohols such as ethylene glycol, diethylene glycol, glycerin, and bisphenol A.

As the carboxyl group-containing monomer, for example, a reaction product of an unsaturated acid such as (meth) acrylic acid and maleic acid, a saturated dibasic acid such as succinic acid and phthalic acid, and glycidyl (meth) acrylate is used. Used.

Examples of the hydrophobic monomer used in the present invention include styrenes such as styrene, α-methylstyrene and vinyltoluene, and (meth) acrylic acid alkyl esters.

Examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate and sec-butyl. (Meth) acrylate, tert-butyl (meth) acrylate, 2-
Methylbutyl (meth) acrylate, 2-ethylbutyl (meth) acrylate, 3-methylbutyl (meth) acrylate, 1,3-dimethylbutyl (meth) acrylate, pentyl (meth) acrylate, 3-pentyl (meth) acrylate, hexyl (meth ) Acrylate, 2
-Ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, 2-ethoxyethyl acrylate, 3-ethoxypropyl acrylate, 2-ethoxybutyl acrylate, 3-ethoxybutyl acrylate, 3 -Ethoxybutyl acrylate, dimethylaminoethyl acrylate and the like can be mentioned.

The alcohol component used for half-esterification is, for example, methanol, ethanol or propanol, and the optionally used monomer is, for example, (meth) acrylamide, N-methylol (meth) acrylamide, diacetone acrylamide. Etc.

As described above, it is possible to synthesize a hydrophilic macromonomer or a hydrophobic macromonomer. Further, the macromonomer synthesized in this manner is subjected to radical copolymerization in the presence of any hydrophilic monomer, hydrophobic monomer and an initiator as listed above to obtain the graft polymer of the present invention. Copolymers can be synthesized.

That is, by random copolymerization of the hydrophilic macromonomer and the above-mentioned hydrophobic monomer, a graft polymer having a hydrophobic trunk and hydrophilic branches is obtained, and the hydrophobic macromonomer and the above-mentioned hydrophilic monomer are also obtained. By random copolymerization with, a graft polymer having a hydrophilic backbone and hydrophobic branches is obtained. Also, there is a concern that the reactivity of the terminal double bond may be low in these macromonomers, but it has been found that they have the same reactivity as the corresponding low-molecular model (polymer, 31 , 988
(1982)).

The graft copolymer thus synthesized is preferably used as a dispersant for the aqueous pigment ink in the present invention. In this case, the weight ratio of the hydrophilic polymer chain portion to the hydrophobic polymer chain portion of this graft copolymer is in the range of 20:80 to 80:20, and the number average molecular weight of the polymer is 1000. To 10,000, and the weight average molecular weight is preferably in the range of 1,500 to 20,000, and the effects of the present invention can be sufficiently exhibited.

These resins are soluble in water or in an aqueous solution in which a base is dissolved. The use of an alkali-soluble resin is preferable because it has the advantages that the viscosity of the dispersion liquid can be reduced and the dispersion is easy. Furthermore, pH 6
The resin that starts aggregation below is particularly preferable for improving the printing density. However, of course, it is not limited to this. The water-soluble resin is 0.1% with respect to the total amount of the recording liquid.
It is preferably contained in the range of 5 to 5% by weight.

The amount of the pigment contained in the ink used in the present invention is 1 to 20% by weight, preferably 2-1.
It is in the range of 2% by weight. As the pigment used in the present invention, any pigment can be used as long as it satisfies the above-mentioned performance, but as the carbon black used in the black ink, carbon black produced by the furnace method or the channel method is used. The primary particle diameter is 15 to 40 μm, the specific surface area by BET method is 50 to 300 m ² / g, the DBP oil absorption is 40 to 150 ml / 100 g, the volatile content is 0.5 to 10%, and the pH is in the range of 2 to 9. Those having a value of are preferred.

For example, NO. 2300, NO. 900,
MCF88, NO. 33, NO. 40, NO. 45, N
O. 52, MA7, MA8, NO. 2200B (Made by Mitsubishi Kasei), RAVEN1255 (Colombia), R
EGAL400R, REGAL330R, REGAL6
60R, MOGUL L (above made by Cabot), Col
or Black FW1, Color Black
FW18, ColorBlack S170, Colo
r Black S150, Printex35, Pr
A commercially available product such as index U (above made by Degussa) can be used.

As the pigment used for the yellow ink, C.I. l. Pigment Yellow 1,
C. l. Pigment Yellow 2, C.I. l.
Pigment Yellow 3, C.I. l. Pigm
ent Yellow 13, C.I. l. Pigment
Yellow 16, C.I. l. Pigment Ye
LLOW 83, a pigment used as a magenta ink includes C.I. l. Pigment Red 5, C.I.
l. Pigment Red 7, C.I. l. Pigme
nt Red 12, C.I. l. Pigment Red
48 (Ca), C.I. l. Pigment Red 4
8 (Mn), C.I. l. Pigment Red 57
(Ca), C.I. l. Pigment Red 112,
C. l. Pigment Red 122 and the like.

As the pigment used as the cyan ink, C.I. l. Pigment Blue 1, C.I.
l. Pigment Blue 2, C.I. l. Pigm
ent Blue 3, C.I. l. Pigment Bl
ue 15: 3, C.I. l. Pigment Blue
16, C.I. l. Pigment Blue 22, C.I.
l. Vat Blue 4, C.I. l. Vat Blue
6 and the like, but not limited to these. In addition, those newly manufactured for the present invention can also be used.

In the recording liquid of the present invention, it is preferable that the entire recording liquid is adjusted to be neutral or alkaline to improve the solubility of the dispersant, which is a water-soluble resin composed of the graft copolymer, and It is desirable because the recording liquid can be excellent in long-term storage stability. However, in this case, it may cause corrosion of various members used in the ink jet recording apparatus. Therefore, it is preferable that the pH value is in the range of 7 to 10.

Examples of the pH adjusting agent include various organic amines such as diethanolamine and triethanolamine, inorganic alkali agents such as alkali metal hydroxides such as sodium hydroxide, lithium hydroxide and potassium hydroxide, and Organic acids and mineral acids can be used, and the pigment and water-soluble resin as described above are dispersed or dissolved in a water-soluble medium.

The aqueous medium preferably used in the recording liquid of the present invention is a mixed solvent of water and a water-soluble organic solvent,
Water is not ordinary water containing various ions,
It is preferable to use ion-exchanged water (deionized water).

In addition, as other optional solvent components which can be used in combination, examples of the water-soluble organic solvent used by mixing with water include, for example, methyl alcohol, ethyl alcohol, n.
-Propyl alcohol, isopropyl alcohol, n-
Butyl alcohol, sec-butyl alcohol, ter
alkyl alcohols having 1 to 4 carbon atoms such as t-butyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyethylene glycol; Polyalkylene glycols such as polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6
-Hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol and other alkylene groups having an alkylene group containing 2 to 6 carbon atoms; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, Lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like.

Among these many water-soluble organic solvents,
Preferred are polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether.

Further, in order to obtain stable ejection, it is effective to add ethanol or isopropyl alcohol in an amount of 1% or more. It is considered that the addition of these solvents makes it possible to more stably foam the recording liquid on the thin film resistor.

The content of the water-soluble organic solvent in the recording liquid of the present invention is generally in the range of 3 to 50% by weight, preferably 3 to 40% by weight, based on the total weight of the recording liquid.
The water used is in the range of 10 to 90% by weight, preferably 30 to 80% by weight, based on the total weight of the recording liquid. In addition to the above components, the recording liquid of the present invention contains a surfactant, a defoaming agent, a surfactant, and a defoaming agent in order to obtain a recording liquid having desired physical properties, if necessary.
A preservative or the like can be added, and a commercially available water-soluble dye or the like can also be added.

For example, the surfactant that can be used is
The ink is not limited as long as it does not adversely affect the storage stability of the ink, and examples thereof include fatty acid salts,
Anionic surfactants such as higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, alkylallyl sulfonates, polyoxyethylene alkyl ethers,
There are nonionic surfactants such as polyoxyethylene alkyl esters, polyoxyethylene sorbitan alkyl esters, acetylene alcohol, and acetylene glycol, and one or more of these can be appropriately selected and used.

The amount used varies depending on the dispersant, but is preferably 0.01 to 5% by weight with respect to the total amount of the ink. At this time, it is preferable to determine the addition amount of the activator so that the surface tension of the recording liquid becomes 30 dyne / cm or more.

As the method for preparing the ink of the present invention, first, the pigment is added to the dispersion resin of the present invention and an aqueous solution containing at least water, the mixture is stirred, and then dispersed using the following dispersing means, if necessary. According to the centrifugation process,
Obtain the desired dispersion. Next, the compound used in the present invention and the components as listed above are added to this dispersion, and the mixture is stirred to prepare a recording liquid. When using an alkali-soluble resin, it is necessary to add a base to dissolve the resin.

Further, it is effective to carry out premixing for 30 minutes or more before the dispersion treatment of the aqueous solution containing the pigment. This premixing operation improves the wettability of the pigment surface and promotes adsorption on the pigment surface.

As the bases added to the dispersion when the alkali-soluble resin is used, amines such as monoethanolamine, diethanolamine, triethanolamine, amine methyl propanol and ammonia, or potassium hydroxide, Inorganic bases such as sodium hydroxide are preferred.

On the other hand, the disperser used in the present invention may be any disperser generally used, and examples thereof include a ball mill, a roll mill and a sand mill. Among them, a high speed type sand mill is preferable, for example, a super mill, a sand grinder, a bead mill,
Agitator mills, Glen mills, Dyno mills, Pearl mills, Cobol mills (all are trade names) and the like can be mentioned.

In the present invention, as a method for obtaining a pigment having a desired particle size distribution, the size of the pulverized media of the disperser is reduced, and the packing ratio of the pulverized media is increased.
Further, methods such as lengthening the processing time, slowing the discharge speed, and classifying with a filter or a centrifuge after crushing are used, but a combination of these methods may be used.

A recording apparatus suitable for recording using the ink of the present invention is an apparatus which applies thermal energy corresponding to a recording signal to the ink in the chamber of the recording head and generates a droplet by the energy. To be

Further, particularly in the present invention, the nozzle surface of the recording head does not need to be ink-repellent treated,
It is more desirable and effective to be treated. When the ink repellent treatment is not carried out, the occurrence of liquid pools in the peripheral portion of the ejection port is remarkable even in the case of the dye-based ink, but particularly when the ink according to the present invention is used, the head subjected to the ink repellent treatment is effective. is there. The ink repellent method is not particularly limited, and examples thereof include treating the head surface with silicon oil, fluorine-containing low molecular weight compounds and high molecular weight compounds.

A specific example of such an ink repellent agent (trade name)
As KP-801 (manufactured by Shin-Etsu Silicon), Defencer (manufactured by Dainippon Ink), CTX-105, 805 (manufactured by Asahi Glass), Teflon AF (manufactured by DuPont), and many others are used. As for the treatment method, for example, a known method disclosed in JP-A-64-31642 can be used.

An example of the structure of the head, which is the main part of the ink jet recording apparatus of the present invention, is shown in FIGS. 1 (a) and 1 (b).
And shown in FIG. The head 13 is made of glass, ceramics, a plastic plate or the like having grooves 14 through which ink passes,
Heating head 15 used for thermal recording (thin film head is shown in the figure, but not limited to this)
It is obtained by bonding and.

The heating head 15 includes a protective film 16 made of silicon oxide and aluminum electrodes 17-1, 17-.
2. A heating resistor layer 18 made of nichrome, a heat storage layer 19, and a substrate 20 having a good heat dissipation property such as alumina. The ink 21 reaches the ejection orifice (fine hole) 22 and forms a meniscus 23 by the pressure P.

Now, when an electric signal is applied to the electrodes 17-1 and 17-2, the area indicated by n of the heating head 15 rapidly generates heat, and bubbles are generated in the ink 21 in contact therewith, The pressure causes the meniscus 23 to project and the ink 21
Is ejected, and becomes a recording droplet 24 from the orifice 22 and flies toward the recording medium 25.

FIG. 2 shows an external view of a multi-head in which many heads shown in FIG. 1 (a) are arranged. The multi-head is made by bonding a glass plate 27 having multi-grooves 26 and a heating head 28 similar to that shown in FIG. 1A is a cross-sectional view of the head 13 along the ink flow path, and FIG. 1B is a cross section taken along the line AB of FIG. 1A.

FIG. 3 shows an example of an ink jet recording apparatus incorporating such a head. In FIG. 3, reference numeral 61 denotes a blade as a wiping member, one end of which is held by a blade holding member to serve as a fixed end, which is in the form of a cantilever. The blade 61 is arranged at a position adjacent to the recording area by the recording head, and in the case of this example,
The recording head is held in a protruding form in the moving path of the recording head.

Reference numeral 62 denotes a cap, which is arranged at a home position adjacent to the blade 61, and has a structure for moving in a direction perpendicular to the moving direction of the recording head to come into contact with the ejection surface for capping. Further, 63 is an ink absorber provided adjacent to the blade 61.
Similarly to the above, it is held in a protruding form in the recording head moving path.

The blade 61, the cap 62 and the absorber 63 constitute an ejection recovery section 64, and the blade 61 and the absorber 63 remove water, dust and dust on the ink ejection port surface. Reference numeral 65 denotes a recording head which has an ejection energy generating means and ejects ink to a recording material facing the ejection port surface where the ejection ports are arranged for recording, and 66 denotes a recording head 65 mounted to move the recording head 65. It is a carriage for performing.

The carriage 66 is slidably engaged with the guide shaft 67, and a part of the carriage 66 is connected (not shown) to a belt 69 driven by a motor 68.
As a result, the carriage 66 can move along the guide shaft 67, and the recording head 65 can move the recording area and its adjacent area.

Reference numeral 51 is a paper feed section for inserting a recording material, and 52 is a paper feed roller driven by a motor (not shown). With such a configuration, the recording material is fed to a position facing the ejection opening surface of the recording head, and is ejected to a paper ejection unit provided with a paper ejection roller 53 as the recording progresses.

In the above structure, when the recording head 65 returns to the home position after the recording is completed, the head recovery unit 64
The cap 62 is retracted from the moving path of the recording head 65, but the blade 61 is projected in the moving path.
As a result, the ejection port surface of the recording head 65 is wiped. When the cap 62 comes into contact with the ejection surface of the recording head 65 to perform capping, the cap 62 moves so as to project into the moving path of the recording head.

When the recording head 65 moves from the home position to the recording start position, the cap 62 and the blade 61 are in the same position as the above-mentioned position during wiping. As a result, even during this movement, the ejection port surface of the recording head 65 is wiped. The above-described movement of the recording head to the home position is performed not only at the end of recording and at the time of ejection recovery, but also at the home position adjacent to the recording area at a predetermined interval while the recording head moves in the recording area for recording. It moves, and the wiping is performed along with this movement.

FIG. 4 is a diagram showing an example of an ink cartridge 45 in which the ink supplied to the head through the ink supply tube is contained. Here, 40 is an ink bag containing supply ink, and a rubber stopper 4 is provided at the tip thereof.
Two are provided. By inserting a needle (not shown) into this stopper 42, the ink in the ink bag 40 can be supplied to the head. An ink absorber 44 receives the waste ink.

The ink jet recording apparatus used in the present invention is not limited to the one in which the head and the ink cartridge are separated as described above, and one in which they are integrated as shown in FIG. 5 is also preferable. Used for.

In FIG. 5, reference numeral 70 denotes an ink jet cartridge in which an ink absorber impregnated with ink is stored, and the ink in the ink absorber has a head portion 71 having a plurality of orifices. It is configured to be ejected as an ink droplet from. Reference numeral 72 is an atmosphere communication port for communicating the inside of the cartridge with the atmosphere. The inkjet cartridge 70 is used in place of the recording head 65 shown in FIG. 3, and is detachable from the carriage 66.

[0077]

The present invention will be described in detail below with reference to examples.
The present invention is not limited to these. Unless otherwise specified, the indication of parts in the text means weight basis. Example 1 (Synthesis of Macromonomer M1) 80 parts of styrene and 20 parts of ethyl acrylate were used in a mixed medium of methyl cellosolve and xylene at a polymerization temperature of 76 ° C. while being added dropwise under N ₂ gas flow to generate azobisiso. Radical chain transfer polymerization was carried out using butyronitrile and thioglycolic acid. The resulting oligomer solution is dehydrated at 130 ° C. under reflux conditions,
Glycidyl methacrylate 10 parts, hydroquinone 0.
01 parts and 0.05 parts of N, N-dimethyldodecylamine were added and reacted at 90 ° C. for 5 hours.

Then, excess glycidyl methacrylate was removed by precipitation purification to obtain a macromonomer M1 having a vinylated terminal. The number average molecular weight of this macromonomer M1 was 1800, and the weight average molecular weight was 4100.

(Synthesis of Graft Copolymer C1) Next, 55 parts of this macromonomer M1 as a solid content, 30 parts of acrylic acid and 15 parts of 2-hydroxyethyl acrylate were used in a mixed solvent of methyl cellosolve and xylene. hand,
Using azobisisobutyronitrile as a catalyst under N ₂ stream, reaction was carried out at 70 ° C. for 8 hours to carry out radical copolymerization. From the reaction solution, the unreacted macromonomer and the monomer were removed by precipitation purification. Obtained graft copolymer C
The number average molecular weight of 1 is 9000, and the weight average molecular weight is 130.
It was 00.

(Preparation of Pigment Dispersion P1) Graft Copolymer C1 1.5 parts Monoethanolamine 1 part Ion-exchanged water 76.5 parts Diethylene glycol 5 parts The above components are mixed and heated to 70 ° C. in a water bath,
Completely dissolve the resin component. 15 parts of carbon black (MCF88 manufactured by Mitsubishi Kasei) newly prototyped in this solution,
After adding 1 part of isopropyl alcohol and performing premixing for 30 minutes, dispersion treatment was performed under the following conditions. Disperser Sand grinder (made by Igarashi Machinery) Grinding media Zirconium beads (1mm
Diameter) Packing rate of crushed media 50% (volume) Crushing time 3 hours Further centrifugal treatment (12000 RPM, 20 minutes) was performed to remove coarse particles to obtain a dispersion P1.

(Preparation of Ink I1) Dispersion P1 30 parts Glycerin 2 parts Diethylene glycol 15 parts N-methylpyrrolidone 5 parts Isopropyl alcohol 3 parts Ion-exchanged water 45 parts The above components are mixed and the pH is adjusted to 8 to 10 with monoethanolamine.
It was adjusted to 10. The ink prepared in this way is treated on the nozzle surface (face surface) with a water repellent CYTOP (trade name, made by Asahi Glass), and the ink is ejected by applying thermal energy according to the recording signal. The test was conducted using an inkjet recording apparatus having a multi-type recording head.

Example 2 (Synthesis of Macromonomer M2) 2-Hydroxyethyl acrylate was reacted with chlorotrimethylsilane to give
Obtain trimethylsilyl etherified ethyl acrylate, wash with water and dry. Then it is dissolved in THF,
Anion polymerization is carried out at −78 ° C. for 4 hours under an N ₂ stream using sodium naphthalene as an initiator.

The obtained living oligomer is reacted with ethylene oxide and then with acrylic acid chloride to vinylate the terminal. Next, hydrolysis treatment is performed with acetic acid (pH 4.5) to remove the trimethylsilyl group. The obtained poly 2-
Hydroxyethyl acrylate (macromonomer M2)
Has a number average molecular weight of 3,000 and a weight average molecular weight of 4,500.
Met.

(Synthesis of Graft Copolymer C2) 40 parts of the macromonomer M2 as a solid content, methacrylic acid 1
5 parts, 30 parts of styrene, and 15 parts of n-butyl acrylate were used, in a mixed solvent of methyl cellosolve and toluene, under a N ₂ stream, using azobisisobutyronitrile as a catalyst and reacting at 80 ° C. for 7 hours. I went. Unreacted macromonomer and monomer were removed from the reaction solution by precipitation purification. The graft copolymer C2 thus obtained had a number average molecular weight of 8,800 and a weight average molecular weight of 14,500.

(Preparation of Pigment Dispersion Liquid P2) Graft Copolymer C2 3 parts Aminomethyl propanol 2 parts Ion-exchanged water 78 parts Diethylene glycol 5 parts The above components are mixed and heated to 70 ° C. in a water bath.
The resin component was completely dissolved. 12 parts of carbon black (manufactured by Mitsubishi Kasei Co., Ltd.) was added to this solution, premixed for 30 minutes, and then dispersed under the following conditions. Dispersing machine Pearl mill (manufactured by Ashizawa) Crushed media glass beads (1 mm
Diameter) Filling ratio of crushed media 50% (volume) Discharge rate 100 ml / min. Further, a centrifugal separation treatment (12000 RPM, 20 minutes) was performed to remove coarse particles to obtain a dispersion P2.

(Preparation of Recording Liquid Ink I2) Dispersion P2 25 parts Glycerin 8 parts Ethylene glycol 5 parts Ethanol 5 parts Demol P (manufactured by Kao) 0.05 parts Ion-exchanged water 56.95 parts The above components are mixed and pH adjusted. Was adjusted to 8 to 10 with aminomethyl propanol. The ink prepared in this way is treated with a water repellent CYTOP (trade name, manufactured by Asahi Glass) on the nozzle surface (face surface), and the ink is ejected by applying thermal energy according to the recording signal. The test was conducted using an inkjet recording apparatus having a multi-type recording head.

Example 3 (Synthesis of macromonomer M3) 30 parts of 2-hydroxyethyl acrylate, 70 parts of Bremmer PE200 (trade name, below), 10 parts of 4,4'-azobis-4-cyanovaleric acid, 80 parts of methanol , Ethyl cellosolve 12
A solution consisting of 0 parts was dropped into a solution consisting of 40 parts of methanol and 260 parts of diethylene glycol at 80 ° C. under a N ₂ stream in 5 hours, and after the reaction was continued for 4 hours, the reflux temperature was 140 to 150. The solvent was removed until the temperature reached.

Glycidyl methacrylate 1 was added to this solution.
0 part, 0.02 part of hydroquinone and 0.15 part of N, N-dimethyldodecylamine were added and the reaction was carried out at 140 ° C. for 4 hours to obtain a diethylene glycol / methyl cellosolve solution of a vinyl group-terminated macromonomer. The number average molecular weight of the macromonomer M3 in this solution was 3,000, and the weight average molecular weight was 7,300. In addition, the above-mentioned Blemmer P
E200 is a CH ₂ = CH- product represented by the formula _{(CH 2 CH 2 O) n} -H (n = 4) Nitto Chemical Corporation.

(Synthesis of Graft Copolymer C3) 40 parts of the above-mentioned macromonomer M3 as a solid content, styrene 35
Part, ethyl acrylate 30 parts, toluene 40 parts, methyl cellosolve 60 parts, azobisisobutyronitrile 0.
A solution of 3 parts was subjected to a polymerization reaction at 80 ° C. for 10 hours under N ₂ gas flow. The resulting graft copolymer C3 is
The number average molecular weight was 9600 and the weight average molecular weight was 12,500.

(Preparation of Pigment Dispersion Liquid P3) Graft Copolymer C3 1.5 parts Ion-exchanged water 77.5 parts Ethylene glycol 5 parts The above components are mixed and heated to 70 ° C. in a water bath,
The resin component was completely dissolved. Carbon black S170 (trade name, made by Degussa) 15 newly prototyped in this solution
Parts and 1 part of isopropyl alcohol were added, and after premixing for 60 minutes, dispersion treatment was carried out under the following conditions. Disperser Sand grinder (made by Igarashi Machinery) Grinding media Zirconium beads (0.5 mm diameter) Packing ratio of grinding media 70% (volume) Grinding time 10 hours Centrifugation treatment (12000 RPM, 20 minutes) is performed to remove coarse particles. A dispersion P3 was obtained.

(Preparation of Ink I3) Dispersion P3 30 parts Glycerin 12 parts Diethylene glycol 15 parts 2-Pyrrolidone 5 parts Isopropyl alcohol 3 parts Surfynol 61 (manufactured by Kawaken Fine Chemicals) 0.1
Part Ion-exchanged water 34.9
Parts The above ingredients were mixed and the pH was adjusted to 8 with monoethanolamine.
It was adjusted to 10. The ink thus prepared is treated with a water repellent defencer (trade name, manufactured by Dainippon Ink and Chemicals) on the nozzle surface (face surface), and the ink is ejected by applying thermal energy according to a recording signal. The test was conducted using an inkjet recording apparatus having an on-demand type multi recording head.

Example 4 (Synthesis of Macromonomer M4) In the same manner as in the synthesis method of Example 1, 40 parts of n-butyl acrylate and 60 parts of α-methylstyrene were used to obtain a hydrophobic macromonomer M4.

(Synthesis of Graft Copolymer C4) Using 60 parts of the above macromonomer M4 and 40 parts of maleic anhydride, solution polymerization was carried out in toluene under the same conditions as in Example 1. After the completion of polymerization, n-propanol was added to 60
The maleic anhydride group was half-esterified with n-propanol by reacting at 3 ° C for 3 hours. Thus, the graft copolymer C4 was obtained. The graft copolymer C4 thus obtained had a number average molecular weight of 12,000 and a weight average molecular weight of 19,200.

(Preparation of Pigment Dispersion Liquid P4 and Ink I4)
In the preparation of the pigment dispersion of Example 1 and the preparation of the ink, the graft copolymer C4 prepared by synthesizing the dispersion resin described above was used.
The pigment dispersion P4, the ink I4, and the printing test were performed in the same manner as in Example 1 except that the above was changed to.

Example 5 (Synthesis of Macromonomer M5) Methyl Methacrylate 2
Macromonomer M5 in the same manner as in Example 3 except that 0 part and 80 parts of Bremmer PE350 (trade name, below) were used.
Was synthesized. The Bremmer PE350 is polyethylene glycol monomethacrylate (made by NOF CORPORATION).

(Synthesis of Graft Copolymer C5) Using 60 parts of the above macromonomer M5, 20 parts of 2-ethoxyethyl methacrylate and 20 parts of methyl methacrylate,
Solution polymerization was carried out in the same manner as in Example 3. The resulting graft copolymer C5 had a number average molecular weight of 8,500 and a weight average molecular weight of 13,800.

(Preparation of Pigment Dispersion Liquid P5 and Ink I5)
In the preparation of the pigment dispersion and the ink of Example 2, the pigment dispersion P5 and the ink I5 were prepared in exactly the same manner as in Example 2 except that the above-mentioned graft copolymer C5 was used as the dispersion resin. And a printing test was conducted.

Example 6 (Synthesis of Macromonomer M6) The product (M1) obtained in Example 1 was used as it was.

(Synthesis of Graft Copolymer C6) Example 1
Radical copolymerization was carried out in the same manner as in Example 1 by using 80 parts of the hydrophobic macromonomer M1 obtained in the above and 20 parts of methacrylic acid. The resulting graft copolymer C6 had a number average molecular weight of 6,500 and a weight average molecular weight of 11,200. (Preparation of Pigment Dispersion Liquid P6 and Ink I6) Pigment dispersion was carried out in the same manner as in Example 1 except that the dispersion resin was changed to the above graft copolymer C6 in the preparation of the pigment dispersion liquid and ink of Example 1. Liquid P6 was prepared, ink I6 was prepared, and a printing test was performed.

Example 7 (Synthesis of Macromonomer M7) The product (M3) obtained in Example 3 was used as it was.

(Synthesis of Graft Copolymer C7) Example 3
80 parts of macromonomer M3 obtained in
Copolymerization was carried out in the same manner as in Example 3 using the parts. The number average molecular weight of the obtained graft copolymer C7 is 460.
0, the weight average molecular weight was 9700.

(Preparation of Pigment Dispersion Liquid P7 and Ink I7)
In the preparation of the pigment dispersion and the ink of Example 3, the pigment dispersion P7 and the ink I7 were prepared in exactly the same manner as in Example 3 except that the above-mentioned graft copolymer C7 was used as the dispersion resin. A printing test was conducted.

Comparative Example 1 The dispersion resin in Example 1 was changed to styrene-butyl acrylate random copolymer (prototype, acid value 116, weight average molecular weight 3700): C1 ', and the others were completely used in Example 1
Pigment Dispersion Liquid P1 ′ and Ink I1 ′ were prepared in the same manner as in, and a printing test was performed.

Comparative Example 2 The dispersion resin used in Example 2 was styrene-maleic acid random copolymer SMA resin 1440 (trade name, ARC).
O Chem. Co. Manufacture, acid value 175, weight average molecular weight 2500): C2 ′, except that pigment dispersion P2 ′ and ink I2 ′ are prepared in the same manner as in Example 2,
A printing test was conducted.

Comparative Example 3 The dispersing resin in Example 3 was changed to condensed naphthalenesulfonic acid soda salt Rome D (trade name, manufactured by San Nobuco Co., Ltd., weight average molecular weight 1800): C3 ′, and others were completely used.
Pigment Dispersion P3 ′ and Ink I3 ′ were prepared in the same manner as in, and a printing test was performed.

(Evaluation Test 1: Print Density) Printing was performed on Canon NP-DRY copy paper using the above ink jet recording apparatus, and the print density of the printed matter was measured with a Macbeth densitometer (TR918).

(Evaluation Test 2: Print Deflection) Continuous printing was carried out using the above-mentioned ink jet recording apparatus, and the number of sheets at which the print deviation occurred was checked.

(Evaluation Test 3: Ink Non-Ejection) Using the above-mentioned ink jet recording apparatus, continuous printing was performed, and the number of sheets at which non-ejection of ink occurred was checked.

(Evaluation Test 4: Liquid Pool) Using the above-mentioned ink jet recording apparatus, continuous printing was performed on ten sheets, and the face surface of the recording head was observed with a microscope. If the face surface was close to the initial state without doing it, it was rated as ◯.

(Evaluation Test 5: Light Resistance and Water Resistance) The above-mentioned printed matter was immersed in tap water for 5 minutes, the print density before and after the test was measured, and the print density residual ratio was calculated. did. Further, the above-mentioned printed matter was irradiated with an atlas fade meter for 200 hours, the printed density before and after the test was measured, and the residual density of the printed density was calculated to obtain the light resistance of the printed matter.

(Evaluation test 6: Scratchability) After printing the above-mentioned printed matter for 5 minutes, the solid portion was rubbed with a finger, and the recording liquid did not adhere to the finger as ◯, slightly adhered as Δ, and clearly adhered. What was done was marked with x.

(Evaluation Test 7: Storage Stability) After sealing the above water-based pigment ink in a glass container and storing it at 60 ° C. for 6 months, pigment particles aggregated or increased in viscosity. The ones that were marked as ◯. These evaluation tests 1 to 7
The results are shown in Table 1.

[0113]

[Table 1]

[0114]

According to the ink, the ink jet recording method and the ink jet recording apparatus of the present invention, when recording is performed using an ink jet printer, the ink at the tip of the head does not solidify even after being left for a long time, which is practical. It has storage stability, can be ejected stably even when driving conditions change and is used for a long time, has excellent reliability, and has robustness such as light resistance and water resistance of printed matter. No sexual problems,
A very useful effect can be obtained.

[Brief description of drawings]

FIG. 1A is a schematic cross-sectional view showing an example of a head,
FIG. 3B is a schematic elevational view showing an example of a head (A-B cut surface).

FIG. 2 is a schematic external view showing an example of a multi-head.

FIG. 3 is a schematic external view showing an example of an inkjet recording apparatus.

FIG. 4 is a schematic cross-sectional view showing an example of an ink cartridge.

FIG. 5 is a schematic external view showing an example of a configuration in which an ink cartridge and a head are integrated.

[Explanation of symbols]

 13 Head 14 Ink Groove 15 Heating Head 16 Protective Film 17-1, 17-2 Aluminum Electrode 18 Heating Resistor Layer 19 Heat Storage Layer 20 Substrate 21 Ink 22 Ejection Orifice 23 Meniscus 24 Recording Droplet 25 Recording Medium 26 Multi-groove 27 Glass Plate 28 Heating Head 40 Ink Bag 42 Rubber Plug 44 Ink Absorber 45 Ink Cartridge 51 Paper Feeding Section 52 Paper Feeding Roller 53 Paper Discharging Roller 61 Blade 62 Cap 63 Ink Absorber 64 Discharge Recovery Section 65 Recording Head 66 Carriage 67 Guide 68 Motor 69 Belt 70 Inkjet cartridge 71 Head 72 Atmosphere communication port

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fumi Takade 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor, Yui Shirota 3-30-2 Shimomaruko, Ota-ku, Tokyo Non non corporation

Claims (5)

[Claims] 1. An aqueous pigment ink for ink jet recording comprising a pigment, a water-soluble resin, a hydrophilic organic solvent and water, wherein the water-soluble resin is (1) (meth) acrylic acid, maleic acid and ( A hydrophilic polymer chain portion containing 80 mol% or more of a monomer selected from the group consisting of (meth) acrylic acid hydroxyalkyl esters, and a monomer selected from the group consisting of styrenes and (meth) acrylic acid alkyl esters. A graft copolymer comprising a hydrophobic polymerization chain portion containing 80% by mole or more of a monomer,
(2) The weight ratio of the hydrophilic polymer chain portion to the hydrophobic polymer chain portion of the copolymer is in the range of 20:80 to 80:20, and (3) the number average of the copolymer. A water-soluble resin for an aqueous pigment ink for inkjet recording, which is a polymer compound having a molecular weight of 1,000 to 10,000 and a weight average molecular weight of 1,500 to 20,000. 2. A water-based pigment ink for ink-jet recording, wherein the water-based pigment ink contains the water-soluble resin according to claim 1. 3. An ink jet recording method using an ink as a recording liquid, wherein the aqueous pigment ink according to claim 2 is used as the recording liquid, and thermal energy corresponding to a recording signal is applied to the recording liquid to form fine particles. An ink jet recording method, wherein recording is performed by ejecting a recording liquid as a droplet from a hole. 4. An ink jet recording apparatus for recording by an ink jet recording method using an ink as a recording liquid, wherein the aqueous pigment ink according to claim 2 is used as the recording liquid. 5. An ink jet recording apparatus for performing recording by an ink jet recording method using ink as a recording liquid, wherein the ink jet recording method is the ink jet recording method according to claim 3.