JPH0987560A - Recording liquid - Google Patents

Abstract

(57) [Summary] [Problem] Water resistance is good even when recorded on plain paper.
High-density recording is possible, the printed matter has excellent abrasion resistance, the printed matter has good printing quality, and it is possible to perform recording with good fastness other than water resistance such as light resistance, and for inkjet and writing instruments. A recording liquid suitable for other uses is provided without stopping. SOLUTION: A soap-free emulsion having carbon black and a glass transition point (Tg) of 20 ° C. or higher in an aqueous medium (for example, a hydrophilic monomer selected from acrylic acid and methacrylic acid, a lower alkyl acrylate and methacrylic acid). It is characterized by containing an acid lower alkyl ester (having a glass transition point of 50 to 100 ° C., which is obtained by soap-free polymerization of a hydrophobic monomer selected from an alkyl group having 1 to 6 carbon atoms). Recording liquid to be.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous medium recording liquid, particularly to an inkjet recording liquid or a recording liquid suitable for a writing instrument.

[0002]

2. Description of the Related Art Conventionally, as a recording liquid for ink jet recording, an aqueous ink in which an acidic dye or a direct dye is dissolved in an aqueous medium, or a solvent-based ink in which an oil-soluble dye is dissolved in an organic solvent has been used. . Since the solvent-based ink uses a solvent and has a problem in terms of environmental safety, its use is limited, and it is not suitable for use in offices and the like. On the other hand, since the water-based ink uses a water-soluble pigment, there is a problem that the recorded matter has poor water resistance, particularly when recorded on plain paper. Further, the recorded matter of the ink using these dyes is insufficient in light resistance. The recording liquid for writing instruments also has the same problems as those for inkjet recording.

In order to improve the above-mentioned problems, an aqueous dispersion ink in which carbon black excellent in water resistance and light resistance is used as a coloring material and carbon black is dispersed in an aqueous medium is used. However, the conventional aqueous dispersion ink of carbon black has a problem that the durability of the recorded matter when the printed matter recorded with it is rubbed with a finger or the like, that is, the abrasion resistance is not sufficient. In order to improve this, it is possible to add a water-soluble resin or a resin emulsion to the recording liquid, but in the system in which the former is added, the viscosity of the recording liquid increases and ejection failure occurs. Further, as an example in which the latter is added, for example, JP-A-3-56573 describes that an emulsion obtained by emulsion polymerization is used as organic ultrafine particles. In JP-A-3-160069, a special emulsion called a core shell emulsion is used. JP-A-4-18462 also describes that a soap-free emulsion can be used, but none of them used in the examples was obtained by soap-free polymerization. JP-A-4-332774
No. 6,212,106 and 6-14557.
None of the emulsions used in No. 0 was obtained by soap-free polymerization. In addition, all of these have insufficient scratch resistance, and carbon black causes aggregation, or a surfactant added to maintain the stability of the emulsion lowers the surface tension of the ink, Will penetrate into the recording material such as paper, making it impossible to perform high-density recording.

[0004]

DISCLOSURE OF THE INVENTION The present invention has excellent water resistance even when recorded on plain paper for ink jet recording or for writing instruments, enables high density recording, and is excellent in abrasion resistance of printed matter. The print quality of the recorded matter is good, and it is possible to record with good fastness other than water resistance such as light resistance.
It is an object of the present invention to provide an aqueous dispersion ink using carbon black, which has good stability when stored for a long time.

[0005]

The gist of the present invention is that carbon black and glass transition point (Tg) are 2 in an aqueous medium.
A recording liquid containing a soap-free emulsion at 0 ° C. or higher.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
As a result of testing various rub resistance improvers on the aqueous dispersion ink of carbon black, the present inventors have found that the soap-free emulsion exhibits a particularly excellent effect as a rub resistance improver, and the present invention has been completed. It is a thing. The recording liquid prepared by using these compounds has good water resistance, can obtain a high-density recorded matter, has excellent scratch resistance of printed matter, and has good fastness other than water resistance such as light resistance. Recording is possible, the stability of the recording liquid is good, and sedimentation of carbon black does not occur during long-term storage.

The soap-free emulsion used in the recording liquid of the present invention is a resin emulsion obtained by a soap-free polymerization method, and in the present invention, it means an aqueous emulsion. Then, using one or more hydrophilic monomers selected from acrylic acid, methacrylic acid, hydroxyethyl acrylate, acrylamide, etc. and one or more hydrophobic monomers selected from acrylic acid esters, methacrylic acid esters, etc. It is an emulsion obtained by soap-free copolymerization. Also, a monomer having both a hydrophobic group and a hydrophilic group in one molecule can be used.

Further, this soap-free emulsion is
It is necessary that the glass transition point (hereinafter, Tg) is 20 ° C. or higher, and among them, those having a particle diameter of 80 nm or less are preferable, and further, Tg is 50 ° C. or higher and the particle diameter is 40 to 80.
Those in the nm range are more preferable. If the Tg is lower than 20 ° C, the effect of improving the abrasion resistance is not sufficient. Particle size 80
If it is larger than nm, the ejection property is poor, and if it is smaller than 40 nm, the abrasion resistance is not sufficiently expressed. A commercially available product may be used as such a soap-free emulsion.

The soap-free emulsion used in the present invention includes hydrophilic monomers selected from acrylic acid and methacrylic acid, acrylic acid lower alkyl esters and methacrylic acid lower alkyl esters (wherein the alkyl group has 1 to 6 carbon atoms). A resin having a glass transition point of 50 to 100 ° C. obtained by soap-free polymerization of a hydrophobic monomer selected from the group consisting of acrylic acid and methacrylic acid as hydrophilic parts and acrylic ester as a hydrophobic part. Is preferred.

If a styrene-based monomer is used as the monomer of the soap-free polymerization copolymer component, there is a problem in the light resistance of the recorded matter, which is not preferable. The amount of the soap-free emulsion added is usually 0.5 to 5% by weight (solid content), preferably 2 to 4.5% by weight (solid content) with respect to the recording liquid. If the amount of soap-free emulsion is less than this range, the abrasion resistance is not improved, and conversely, if it is more than this range, the viscosity tends to increase, and the ejection stability is impaired, which is not preferable.

As the carbon black used in the recording liquid of the present invention, commercially available general products can be used, the primary particle diameter of which is 10 to 100 nm, and the DBP oil absorption is 40 to 150 ml / 100 g. A substance having a pH of 3 to 9 is preferable, a substance having a primary particle diameter of 10 to 50 nm and a DBP oil absorption amount of 50 to 130 ml / 100 g is particularly preferable. Specifically, products of Mitsubishi Chemical Co., Ltd. # 5, # 10, # 3
0, # 33, # 40, # 42, # 45, # 48, # 5
2, # 95, # 260, # 2600, MA7, MA8,
MA11, MA100, MA230, MA600 (all are trade names) and the like. In addition, these carbon blacks are chemically treated (ozone oxidation treatment, fluorination treatment, etc.), and those obtained by physically or chemically bonding dispersants, surfactants, etc. (grafted carbon, dispersants are dispersed). It is also possible to use carbon black or the like, which was previously adsorbed in advance. Further, these pigments such as carbon black may be used in combination of two or more kinds. The physical property values of carbon black are shown in Table 1 below.

Carbon black is usually used in the range of 1 to 10% by weight based on the total weight of the recording liquid, but 3 to 8% by weight.
Is preferred. A dispersant may not be used in the recording liquid of the present invention, but may be added. However, when adding, the kind and amount suitable for the dispersion of carbon black are selected and used. In particular, when preparing a recording liquid and adding an emulsion before milling and dispersion treatment, it is preferable not to use a dispersant.

When a dispersant is used, various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, polymeric dispersants and the like can be mentioned. Anionic surfactants include fatty acid salts, alkyl sulfate ester salts, alkylbenzene sulfonates, alkylnaphthalene sulfonates, alkylsulfosuccinates, alkyl diphenyl ether disulfonates, alkyl phosphates, polyoxyethylene alkyl sulfate salts , Polyoxyethylene alkylaryl sulfate ester salts, alkane sulfonates,
Examples include naphthalenesulfonic acid formalin condensates, polyoxyethylene alkyl phosphates, α-olefin sulfonates, and the like. As the nonionic surfactant, polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, polyoxyethylene derivatives, oxyethylene, oxypropylene block copolymers, sorbitan fatty acid esters,
Examples thereof include polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, glycerin fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene alkylamines and the like. Examples of the cationic surfactant and the amphoteric surfactant include alkylamine salts, quaternary ammonium salts, alkylbetaines, and aminooxides. As the polymer dispersant, polyacrylic acid, styrene / acrylic acid copolymer, styrene / acrylic acid / acrylic acid ester copolymer, styrene / maleic acid copolymer, styrene / maleic acid / acrylic acid ester copolymer are used. Polymer, styrene / methacrylic acid copolymer, styrene / methacrylic acid / acrylic ester copolymer, styrene / maleic acid half ester copolymer, vinylnaphthalene /
Examples thereof include maleic acid copolymers, vinylnaphthalene / acrylic acid copolymers and salts thereof.

The dispersant is usually used in the range of 3 to 100% by weight, preferably 5 to 50% by weight, based on the carbon black. The aqueous medium used in the recording liquid of the present invention is mainly water, but it is preferable to use a water-soluble organic solvent added to water. As water-soluble organic solvents, ethylene glycol, propylene glycol, butylene glycol,
Diethylene glycol, triethylene glycol, polyethylene glycol (average molecular weight about 190 to 400),
Glycerin, alkyl ethers of the above glycols,
N-methylpyrrolidone, 1,3-dimethylimidazolinone, thiodiglycol, 2-pyrrolidone, sulfolane,
Examples include dimethyl sulfoxide, diethanolamine, triethanolamine, ethanol, isopropanol and the like.

The amount of the water-soluble organic solvent used in the recording liquid is 5 to 5.
The range is 30% by weight, but 10 to 20% by weight is preferable. One of these carbon blacks, the polymer and the organic solvent may be used alone, but in some cases, two or more of them may be used in combination to further enhance the effect.

In addition to the above components, a surface tension adjusting agent, a water-soluble resin, an antifungal agent, a bactericidal agent, a pH adjusting agent, urea and the like may be added to the recording liquid of the present invention as required. The method of preparing the recording liquid of the present invention is carried out by mixing the above-mentioned components, grinding the carbon black into fine particles using a disperser, and subjecting the fine particles to a dispersion treatment. As the disperser, a ball mill, a roll mill, a sand grind mill or the like is used, and a sand grind mill is particularly preferable. After milling and dispersion treatment, coarse particles are removed using a filter or a centrifuge. It is desirable that the particle size of the carbon black be adjusted to 1 μm or less. Components other than carbon black, a dispersant, and water may be added after grinding and dispersion treatment. Also, milling,
Since the dispersion treatment can be efficiently carried out by preparing it at a high concentration, it is preferable to adjust the concentration of the recording liquid by finally diluting the treatment liquid prepared at a high concentration with an aqueous medium.

[0017]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited thereto. Example 1 (Preparation of recording liquid) Composition of dispersion liquid Amount used (part) Glycerin 16 Ethylene glycol 18 Carbon black # 260 11 (manufactured by Mitsubishi Chemical Corporation) Liporan PB-800 2 (trade name, α-olefin sulfonic acid Sodium salt type anionic surfactant, product of Lion Co., Ltd. Deionized water 53 ──────────────────────────────── ─ 100 in total

The above components were placed in a stainless steel container and crushed for 60 hours using a sand grinder together with 152 parts of glass beads having an average diameter of 0.5 mm.
The obtained dispersion was diluted with 100 parts of ion-exchanged water and stirred, and then an aqueous soap-free emulsion liquid (trade name: Jacryl C-37 (translucent liquid), Rohm & Haas product, solid content 25 to 30%, Tg: 60 ° C., minimum film forming temperature 40 ° C., average particle size 40 nm) 27 parts, and No.
The liquid obtained by pressure filtration using 5C filter paper was used as a recording liquid.

(Printing test) An ink jet printer (a product of Hewlett-Packard Company, trade name: Desk) was prepared using the recording liquid obtained by the method described in the above example.
Inkjet recording on electrophotographic paper (Xerox product, 4024 paper) with Writer C)
Stable and good dischargeability without clogging was obtained, and a print with good print quality was obtained.

(Evaluation of Printing Density) The density of the printed matter obtained in the above printing test was measured using a Macbeth reflection densitometer (RD914). The evaluation results are shown in Table 2 below.

(Water resistance test) The printed matter obtained in the printing test was immersed in tap water in a beaker for 5 seconds. After the printed matter is dried,
The presence or absence of character stains was visually evaluated. The results are classified as follows and shown in Table 2 below. ○ ────Almost no stains on the character △ ────Slightly stains on the characters, but there is no practical problem.

(Light resistance test) The printed matter was visually evaluated for discoloration and fading after irradiation for 100 hours using a xenon fade meter (manufactured by Suga Test Instruments Co., Ltd.). The results are classified as follows and shown in Table 2 below. ○ ────Good △ ──── Discoloration and discoloration, but practically no problem × ──── Discoloration and discoloration is severe

(Storage stability test of recording liquid) The recording liquid was sealed in a Teflon container and stored at 60 ° C for 1 month. The presence or absence of gelation or precipitate was visually evaluated. The results are classified as follows and shown in Table 2 below. ○ ──── Almost no gelation or precipitate △ ──── A slight gelation or precipitate is observed, but there is no problem in practical use × ──── Gelation or precipitation is severe

(Abrasion resistance test) The presence or absence of background stain when the printed matter obtained in the print test was traced from above with a finger was visually judged.
The results are classified as follows and shown in Table 2 below. ○ ─── Almost no background stain △ ─── Slightly background stain, but practically no problem × ─── Severe background stain

Example 2 (Preparation of Recording Liquid) Composition of Dispersion Amount Used (Part) Glycerin 16 Ethylene Glycol 18 Carbon Black MA8 11 (Mitsubishi Chemical Co., Ltd. Product) POLYSTAR S2-1020 (Nonvolatile) 2 (trade name) , Styrene-maleic acid type copolymer (anionic surfactant), NOF CORPORATION product ion-exchanged water 53 ───────────────────── ────────── Total 100

The above components were placed in a stainless steel container and crushed for 60 hours by using a sand grinder together with 152 parts of glass beads having an average diameter of 0.5 mm.
The obtained dispersion was diluted with 120 parts of ion-exchanged water and stirred, and then 7 parts of an aqueous soap-free emulsion liquid (trade name: Jacryl C-37) was added. The liquid obtained by pressure filtration using 5C filter paper was used as a recording liquid. The printing test, the water resistance test, the light resistance test, the storage stability test, and the evaluation were performed in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

Example 3 (Preparation of Recording Liquid) Composition of Dispersion Amount Used (Part) Glycerin 16 Ethylene Glycol 18 Carbon Black MA230 11 (Product Name, Mitsubishi Chemical Corporation Product) Polystar OM (Nonvolatile) 2 (Product Name, diisobutylene-maleic acid copolymer (anionic surfactant, product of NOF CORPORATION) Ion-exchanged water 53 ──────────────────── ─────────── Total 100

Each of the above components was placed in a stainless steel container and pulverized with 152 parts of glass beads having an average diameter of 0.5 mm using a sand grinder for 60 hours.
The obtained dispersion was diluted with 100 parts of ion-exchanged water and stirred, and then 27 parts of an aqueous soap-free emulsion liquid (trade name, Jacryl C-37) was added. The liquid obtained by pressure filtration using 5C filter paper was used as a recording liquid. The printing test, the water resistance test, the light resistance test, the storage stability test, and the evaluation were performed in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

Example 4 (Preparation of Recording Liquid) Composition of Dispersion Amount Used (Part) Glycerin 16 Ethylene Glycol 18 Carbon Black # 960B 11 (trade name, Mitsubishi Chemical Co., Ltd. product) Liporan PB-800 3 Ion-exchanged water 52 ─────────────────────────────── Total 100

Each of the above components was placed in a stainless steel container and pulverized with 152 parts of glass beads having an average diameter of 0.5 mm for 60 hours using a sand grinder.
The obtained dispersion was diluted with 100 parts of ion-exchanged water and stirred, and then 27 parts of an aqueous soap-free emulsion liquid (trade name, Jacryl C-37) was added. The liquid obtained by pressure filtration using 5C filter paper was used as a recording liquid. The printing test, the water resistance test, the light resistance test, the storage stability test, and the evaluation were performed in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

Example 5 (Preparation of Recording Liquid) Composition of Dispersion Amount Used (Part) Glycerin 16 Ethylene Glycol 18 Carbon Black # 10 11 (trade name, product of Mitsubishi Chemical Corporation) Liporan PB-800 1 ion-exchanged water 54 ─────────────────────────────── Total 100

Each of the above components was placed in a stainless steel container and crushed for 60 hours using a sand grinder together with 152 parts of glass beads having an average diameter of 0.5 mm.
The obtained dispersion was diluted with 100 parts of ion-exchanged water and stirred, and then 27 parts of an aqueous soap-free emulsion liquid (trade name, Jacryl C-37) was added. The liquid obtained by pressure filtration using 5C filter paper was used as a recording liquid. The printing test, the water resistance test, the light resistance test, the storage stability test, and the evaluation were performed in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

Example 6 (Preparation of Recording Liquid) Composition of Dispersion Amount Used (Part) Glycerin 16 Ethylene Glycol 18 Carbon Black MA220 11 (trade name, manufactured by Mitsubishi Chemical Corporation) Emulgen A500 1 (trade name, ethylene oxide) Monoalkyl ethers, nonionic surfactants, Kao product) Ion-exchanged water 54 ───────────────────────────── ── Total 100

Each of the above components was placed in a stainless steel container and crushed for 60 hours using a sand grinder together with 152 parts of glass beads having an average diameter of 0.5 mm.
The obtained dispersion was diluted with 100 parts of ion-exchanged water and stirred, and then 27 parts of an aqueous soap-free emulsion liquid (trade name, Jacryl C-37) was added. The liquid obtained by pressure filtration using 5C filter paper was used as a recording liquid. The printing test, the water resistance test, the light resistance test, the storage stability test, and the evaluation were performed in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

Comparative Example 1 (Preparation of Recording Liquid) The same procedure as in Example 1 was carried out except that ion-exchanged water was used in place of the aqueous soap-free emulsion liquid Jacryl C-37 (trade name) in Example 1. A recording liquid was prepared and the obtained liquid was used as the recording liquid. Printing test,
The water resistance test, the light resistance test, the storage stability test, the abrasion resistance test and the evaluation thereof were performed in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

Comparative Example 2 (Preparation of Recording Liquid) Instead of using the water-based soap-free emulsion liquid Jacryl C-37 (trade name) in Example 1, VONDIC 1670NS (trade name, emulsion polymerization / milky white liquid, Dainippon Ink and Co., Ltd. ) A recording liquid was prepared in the same manner as in Example 1 except that an emulsion having a product, a solid content of 30% and a minimum film forming temperature of 40 ° C.) was used, and the obtained liquid was used as the recording liquid. The printing test, the water resistance test, the light resistance test, the storage stability test, the abrasion resistance test and the evaluation thereof were performed in the same manner as in Example 1. The evaluation results are shown in Table 2 below.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

EFFECTS OF THE INVENTION By using the recording liquid of the present invention, even when recorded on plain paper, the water resistance is good, high density recording is possible, the printed material is excellent in abrasion resistance, and the printed material is printed. It is possible to record with good quality and fastness other than water resistance such as light resistance. Since the present invention has the above-mentioned characteristics, it is not limited to ink jet and writing instruments, and can be used as a recording liquid for other purposes.

Claims (4)

[Claims] 1. A recording liquid comprising an aqueous medium containing carbon black and a soap-free emulsion having a glass transition point (Tg) of 20 ° C. or higher. 2. A soap-free emulsion is selected from hydrophilic monomers selected from acrylic acid and methacrylic acid, acrylic acid lower alkyl esters and methacrylic acid lower alkyl esters (wherein the alkyl group has 1 to 6 carbon atoms). The recording liquid according to claim 1, wherein the glass transition point obtained by soap-free polymerization of the hydrophobic monomer is 50 to 100 ° C. 3. A soap-free emulsion having an average particle size of 4
The recording liquid according to claim 1 or 2, wherein the recording liquid has a thickness of 0 to 80 nm. 4. A soap-free emulsion (solid content) is contained in an amount of 0.5% by weight to 5% by weight.
The recording liquid according to claim 3.