JP2005200528A - Cationic polymerizable composition and hardening method using the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cationic polymerizable composition in which the dipersibility of a pigment to be a coloring material is satisfactory and a dark reaction can be suppressed, and which is superior in long term storage, highly sensitive, and can be hardened rapidly even in a thin film state, and a hardening method using the composition. <P>SOLUTION: The cationic polymerization composition which contains a cationic polymerization compound, a cationic polymerization initiator, a coloring material, a dispersing agent, and a basic compound as a polymerization inhibitor, is characterized in that the coloring material is a pigment surface-treated by using any of polarity, acids, and bases. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a colored cationic polymerizable composition that is cured by ultraviolet rays and a curing method using the same, and in particular, is excellent in storage stability, and particularly has a low viscosity and a stable viscosity over a long period of time, such as flexographic ink and inkjet ink. The present invention relates to a required cationic polymerizable composition and a curing method using the same.

  The cationic polymerizable composition is not subject to polymerization inhibition by oxygen at the time of polymerization, has a small odor, and can be reduced in viscosity by using oxetane, vinyl ether, etc., so that a curable composition for flexographic ink, inkjet ink, and three-dimensional modeling is used. Application to an adhesive for electronic materials that require high leveling properties is being studied.

  The cationic polymerizable composition mainly composed of oxetane and alicyclic epoxy has a problem of long-term preservation because a dark reaction proceeds with a very small amount of acid.

  Japanese Patent Application Laid-Open Nos. 2000-186079 and 2003-292606 add basic compounds, and Patent Document 1 attempts to improve storage stability by adding water. However, there is no description about the surface treatment of the pigment.

  On the other hand, when a polymerizable composition is used as an ink, a pigment is usually used as a coloring material and dispersed. When used as an ink-jet ink, the dispersibility of the pigment greatly affects the discharge properties. Examples of the ultraviolet curable ink-jet ink include WO99 / 29787, WO99 / 29788, WO97 / 31071, JP-A-5-214280, JP-A-2002-188025, JP-A-2003-321628, JP-A-2003-321629, and Patent Document 2. Has been proposed. However, there is no description about the polymerization inhibitor as a cationically polymerizable composition.

  The UV curable ink jet recording system has the advantage that it can be recorded on a substrate that does not absorb ink, but on the other hand, the reactive diluent (polymerizable monomer, oligomer, etc.) evaporates or shrinks. However, since it remains as it is, there is a drawback that the image becomes embossed and the texture is impaired.

  The present inventor has studied to obtain a high image quality by ejecting ink droplets of a finer size and leveling the droplets thinly to a level of 5 μm or less with an ultraviolet curable ink jet recording system. . In such thin film curing, radically polymerizable inks are strongly affected by oxygen inhibition, and it is difficult to achieve high sensitivity. On the other hand, the cationic polymerizable ink can be highly sensitive even in a thin film.

However, when a cationically polymerizable composition is used as an ink, using only the above technique suppresses both reaggregation of the dispersed pigment as a colorant and dark reaction of the polymerizable composition, and provides long-term stability. It was difficult to obtain curing sensitivity and to obtain discharge stability with a fine droplet size.
JP 2003-252979 A JP 2003-253155 A

  The object of the present invention is to suppress dispersibility of a pigment as a coloring material, dark reaction of the polymerizable composition, excellent long-term storage stability, and high sensitivity cationic polymerizable composition that can be cured at high speed even in a thin film state. It is providing a thing and the hardening method using the same.

The above object of the present invention is achieved by the following configurations.
(Claim 1)
In a cationically polymerizable composition containing a cationic polymerizable compound, a cationic polymerization initiator, a colorant, a dispersant, and a basic compound as a polymerization inhibitor, the colorant is surface-treated with one of polar, acid, and base. A cationically polymerizable composition characterized by being a pigment.
(Claim 2)
2. The cationically polymerizable composition according to claim 1, wherein the surface treating agent of the pigment is a sulfonic acid modified product of the pigment.
(Claim 3)
The cationically polymerizable composition according to claim 1 or 2, wherein the dispersant is a polymer dispersant having a base.
(Claim 4)
The cationically polymerizable composition according to any one of claims 1 to 3, wherein the acid value of the dispersant is larger than the amine value.
(Claim 5)
A curing method, comprising curing the cationically polymerizable composition according to any one of claims 1 to 4 by irradiating with ultraviolet rays in a thin film state of 5 μm or less.

  According to the present invention, a highly sensitive cationic polymerizable composition capable of suppressing dispersibility of a pigment serving as a colorant and a dark reaction of the polymerizable composition, having excellent long-term storage stability and capable of being cured at high speed even in a thin film state, and A curing method using this can be provided.

  As a result of intensive studies, the present inventor has found that a cationic polymerizable composition, a cationic polymerization initiator, a coloring material, a dispersing agent and a cationic polymerizable composition containing a basic compound as a polymerization inhibitor, the coloring material is polar, acid The cationically polymerizable composition is characterized by being a pigment surface-treated with any of the bases, and the dispersibility of the pigment as the colorant and the dark reaction of the polymerizable composition are suppressed, and it is excellent in long-term storage The present inventors have found that a highly sensitive cationic polymerizable composition capable of being cured at high speed even in a thin film state and a curing method using the same can be obtained.

  In cationic polymerization, it is preferable to add a base (excluding those derived from dispersants and pigments) as a polymerization inhibitor, but if added simply, the polymerization inhibitor has polarity, so the bond between the pigment and the dispersant tends to be broken. . In the present invention, in order to further strengthen the bond between the pigment and the dispersant, the surface of the pigment is surface-treated with one of polar, acid, and base, thereby improving the stability of the pigment and the dark reaction of the polymerizable composition. It can be prevented at the same time.

  The present invention will be described in detail below.

[Pigment]
The cationically polymerizable composition of the present invention contains a pigment.

  The pigment needs to be subjected to any surface treatment of polar, acid, or base. As the surface treatment method, it is preferable to use a synergist having a structure similar to that of the pigment and subjected to any of polar, acid and base treatment.

  Synergists have the same structure as pigments, and are modified with polar groups such as acidic groups and basic groups, or organic substances having organic pigment mother nuclei, with polar groups bonded directly or through joints. Say what you are. The dispersibility of the pigment is improved by adsorbing it on the pigment surface and bonding it to the dispersant. Most of these synergists are inferior in light resistance, and excessive treatment cannot exhibit the light resistance of the original pigment.

  Examples of the polar group include a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a boric acid group, and a hydroxyl group. Preferred are a sulfonic acid group and a carboxylic acid group. In the present invention, a sulfonic acid group is particularly preferred.

  When a sulfonic acid modified product of a pigment is used as a pigment surface treatment agent, the dispersion stability is particularly good even in the presence of a polymerization inhibitor. In this case, a sulfonic acid-modified pigment similar to the pigment to be dispersed is preferable. For example, when using phthalocyanine blue as a pigment, it is preferable to use a phthalocyanine sulfonic acid compound as a surface treatment agent, when using quinacridone as a pigment, a quinacridone sulfonic acid compound, and when using benzimidazolone, a benzimidazolone sulfonic acid compound is preferably used. .

  Examples of a method for obtaining pigment particles having a polar group on the surface include WO97 / 48769, JP-A-10-110129, JP-A-11-246807, JP-A-11-57458, JP-A-11-189739, JP-A-11-189739. By treating the surface of the pigment particles described in JP-A Nos. 11-323232 and 2000-265094 with an appropriate oxidizing agent, polar groups such as sulfonic acid groups or salts thereof are formed on at least a part of the pigment surface. The method to introduce is mentioned. Specifically, it is prepared by oxidizing carbon black with concentrated nitric acid, or in the case of color pigments by oxidizing with sulfamic acid, sulfonated pyridine salt, amide sulfuric acid, etc. in sulfolane or N-methyl-2-pyrrolidone. can do. A pigment dispersion can be obtained by removing and purifying a substance that has been excessively oxidized and becomes water-soluble by these reactions. Moreover, when a sulfonic acid group is introduced onto the surface by oxidation, the acidic group may be neutralized with a basic compound as necessary.

  Other methods include a method of adsorbing the pigment derivatives described in JP-A-11-49974, JP-A-2000-273383, JP-A-2000-303014, etc. on the surface of the pigment particles by a treatment such as milling. Examples include a method of dissolving the pigment described in each publication such as 2002-179777, 2002-20141, and the like together with a pigment derivative, followed by crystallization in a poor solvent. Pigment particles having a polar group on the surface can be obtained.

  In the present invention, the polar group may be free or in a salt state, or may have a counter salt. Examples of the counter salt include inorganic salts (lithium, sodium, potassium, magnesium, calcium, aluminum, nickel, ammonium) and organic salts (triethylammonium, diethylammonium, pyridinium, triethanolammonium, etc.), preferably 1 A counter salt having a valence.

  As the synergist, those modified with acid such as sulfonic acid modification, carboxyl group modification and the like having an amine value larger than the acid value are preferable.

  These synergists are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  In the present invention, the amine value of the pigment is larger than the acid value, and the difference is preferably 1 mg / g KOH or more and less than 10 mg / g. The acid value and amine value of the pigment can be determined by potentiometric titration. For example, it can be measured by the method described in Color Material Association Journal 61, [12], 692-698 (1988).

Various pigments can be used as the pigment that can be used in the present invention. The following pigments can be used as specific examples of the pigment, but the present invention is not limited to these.
C. I. Pigment Yellow;
1, 2, 3, 12, 13, 14, 16, 17, 73, 74, 75, 81, 83, 87, 93, 95, 97, 98, 109, 114, 120, 128, 129, 138, 151, 154, 180
C. I. Pigment Red;
5, 7, 12, 22, 38, 48: 1, 48: 2, 48: 4, 49: 1, 53: 1, 57: 1, 63: 1, 101, 112, 122, 123, 144, 146, 168, 184, 185, 202
C. I. Pigment Violet;
19, 23
C. I. Pigment Blue;
1, 2, 3, 15: 1, 15: 2, 15: 3, 15: 4, 18, 22, 27, 29, 60
C. I. Pigment Green;
7, 36
C. I. Pigment Black;
7
C. I. Pigment White;
6, 18, 21
For example, a process color ink set having preferable pigment types is prepared by appropriately combining four types of the following pigments.
Y: C.I. I. Pigment Yellow; 120, 128, 74, 83, 138, 151, 120
M: C.I. I. Pigment Violet; 19,122
C :. I. Pigment Blue; 15; 4
K: C.I. I. Pigment Black; 7
W: C.I. I. Pigment White; 6
For pigment dispersion, the selection of the pigment, dispersant, and dispersion medium, dispersion conditions, and filtration conditions are appropriately set so that the average particle diameter of the pigment particles is 80 to 150 nm. For the dispersion of the pigment, a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, a paint shaker, or the like can be used. The average particle diameter can be measured by laser scattering or the like. By controlling the particle size, when the cationic polymerizable composition is used as an inkjet ink (hereinafter also referred to as ink), the clogging of the head nozzle is suppressed, and the storage stability of the ink, the transparency of the ink, and the curing sensitivity are maintained. Can do.

  In the cationically polymerizable composition of the present invention, the pigment concentration is preferably 1 to 10% by mass of the entire cationically polymerizable composition.

[Dispersant]
In the present invention, the dispersion stability is improved by using a dispersant having an acid value larger than the amine value. The acid value of the dispersant is larger than the amine value, and the difference is preferably 1 mg / g KOH or more and less than 30 mg / g KOH. If it is less than 1 mg / g KOH, the effect is not obtained, and if it is 30 mg / g KOH or more, there is a concern that it is cured by a thermal reaction. The acid value and amine value of the dispersant can be determined by the above potentiometric titration as in the case of the pigment.

  As the dispersant, any of low molecular weight and high molecular weight can be used, but a polymer type dispersant is preferable. Polymer type dispersants preferably have a base or acid as an adsorption site for the pigment, and good results can be obtained with either a base or an acid. However, when dispersing a surface-treated pigment, a base should be used. The polymer dispersant possessed has particularly good dispersion stability. Even in the case of a basic dispersant, when the amine value and acid value are measured, the amine value is not necessarily higher than the acid value. The present invention pays attention to this point, and has discovered that, as a whole, the dispersant has a higher acid value than the amine value for the discharge stability, rather than the type of anchor. The weighted average value can be used for the amine value and acid value when a plurality of dispersants are used.

  Specific examples of the polymeric dispersant include Ajinomoto Fine Techno Co., Ltd. Ajisper PB822, Ajisper PB821, PB817, Avisia Solsperse 24000GR, 32000, Enomoto Kasei Disparon DA-703-50, DA-705, DA-725, etc. Is mentioned.

  The amount of the dispersant used is 10 to 100% by mass, preferably 15 to 50% by mass, based on the pigment.

[Cationically polymerizable compound]
As the cationically polymerizable compound that can be used in the present invention, various known cationically polymerizable compounds can be used. For example, in JP-A-6-9714, JP-A-2001-31892, 2001-40068, 2001-55507, 2001-310938, 2001-310937, 2001-220526, etc. Examples include epoxy compounds, vinyl ether compounds, oxetane compounds and the like.

  In the case of a cationically polymerizable composition, it is preferable to contain at least one oxetane compound and at least one compound selected from an epoxy compound and a vinyl ether compound. Particularly, an oxetane compound and an alicyclic epoxy compound are used in combination. It is preferable to do. As the epoxy compound, an alicyclic epoxide is particularly preferable. As the alicyclic epoxide, a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring is converted to an appropriate oxidation such as hydrogen peroxide or peracid. A cyclohexene oxide or cyclopentene oxide-containing compound obtained by epoxidation with an agent is preferred.

(Cationic polymerization initiator)
In the present invention, in order to perform the curing reaction more efficiently, a cationic polymerization initiator is added and cured. The polymerization initiator is a radical generator when a radical polymerizable compound is used as the polymerizable compound, and is a photoacid generator when a cationic polymerizable compound is used as the polymerizable compound as in the present invention.

  As the photoacid generator, for example, a chemically amplified photoresist or a compound used for photocationic polymerization is used (edited by Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), 187. To page 192). Examples of compounds suitable for the present invention are listed below.

First, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium, etc. be able to.

  Specific examples of onium compounds that can be used in the present invention are shown below.

  Secondly, sulfonated substances that generate sulfonic acid can be mentioned, and specific compounds thereof are exemplified below.

  Of these, triarylsulfonium salts are preferred. Of the sulfonium salts, the monocation type is preferred. For example, an initiator containing a dicationic type salt, such as UVI6992, destabilizes the dispersibility of the pigment.

  Thirdly, halides that generate hydrogen halide can also be used, and specific compounds thereof are exemplified below.

  Fourthly, an iron allene complex can be mentioned.

  As the cationic polymerization initiator, a commercially available product can be used as it is. Obtained under CI-1370, CI-2064, CI-2397, CI-2624, CI-2624, CI-2734, CI-2758, CI-2823, CI-2855 and CI-5102 as representative examples of commercial products Possible commercial products (both made by Nippon Soda Co., Ltd.), commercial products available under PHOTOINITIATOR 2047 (made by Rhodia), commercial products available under the trade names UVI-6974 and UVI-6990 (both unions) Carbite).

(Polymerization inhibitor)
In the present invention, a polymerization inhibitor that suppresses polymerization by heat or actinic rays is added to the cationic polymerizable composition. In the present invention, a basic compound is used as a polymerization inhibitor. As the basic compound, basic inorganic compounds such as alkali metal hydroxides and basic organic compounds such as amines can be used.

  Examples of the basic inorganic compound include lithium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate, magnesium hydroxide, calcium hydroxide and potassium carbonate. Among these, for the cationically polymerizable compound, From the viewpoint of solubility, alkali metal hydroxides such as lithium hydroxide, sodium hydroxide and potassium hydroxide are preferred.

  In addition, as the basic organic compound, a wide range of bases such as amine compounds and quaternary ammonium salts can be used, but those that are not ionic salts from the viewpoint of dispersion stability and compatibility with the polymerizable composition. An amine compound is preferable. Examples of the amine compound include octylamine, naphthylamine, xylenediamine, dibenzylamine, diphenylamine, dibutylamine, dioctylamine, dimethylaniline, quinuclidine, tributylamine, trioctylamine, tetramethylethylenediamine, tetramethyl-1,6- Monovalent tertiary alkanolamines such as hexamethylenediamine, hexamethylenetetramine, dimethylaminoethanol, dimethylamino-2-propanol and dimethylaminomethylpropanol, and third compounds such as dimethylisopropylamine and dimethyloctylamine. Secondary alkylamines. Of these, dimethylamino-2-propanol, dimethylaminomethylpropanol and dimethylisopropylamine are preferable for ink applications because they are excellent in pigment dispersion stability.

  The amine compound is preferably added in an amount of 0.01 to 1% by mass based on the entire cationic polymerizable composition. If it is less than 0.01% by mass, storage stability cannot be obtained. When it is larger than 1% by mass, the curing sensitivity is lowered.

  Other polymerization inhibitors can be used in combination. As the polymerization inhibitor that can be used in combination, various compounds are known, and those widely blended in general polymerizable compositions can be used as they are. For example, phenolic antioxidants, amines In addition to compounds, phosphorus-based antioxidants, hydroquinone monomethyl ether widely used for (meth) acrylic monomers, hydroquinone, t-butylcatechol, pyrogallol, water and the like can be used. These are detailed in “Development Technology of Polymer Additives” (issued by CMC).

  These polymerization inhibitors are preferably added at the time of preparing the pigment dispersion. However, excessive addition of the polymerization inhibitor causes a decrease in sensitivity as the cationic polymerizable composition. It is desirable that the amount is set appropriately so as to prevent polymerization at the time of pigment dispersion while maintaining the storage stability. Or it is preferable to mix | blend excessively and to extract after dispersion | distribution and to reduce the quantity of a polymerization inhibitor.

[Other additives]
Moreover, although the cationically polymerizable composition of the present invention is cured by irradiation with ultraviolet rays, a photosensitizer can be used in combination in order to perform the curing reaction more efficiently. Examples of such a photosensitizer include triethanolamine, methyldiethanolamine, triisopropanolamine, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, benzoic acid ( 2-dimethylamino) ethyl, 4-dimethylaminobenzoic acid (n-butoxy) ethyl, amines such as 4-dimethylaminobenzoic acid 2-ethylhexyl, cyanine, phthalocyanine, merocyanine, porphyrin, spiro compound, ferrocene, fluorene, fulgide , Imidazole, perylene, phenazine, phenothiazine, polyene, azo compound, diphenylmethane, triphenylmethane, polymethine acridine, coumarin, ketocoumarin, quinacridone, indigo, styryl, pyriri Compounds, pyromethene compounds, pyrazolotriazole compounds, benzothiazole compounds, barbituric acid derivatives, thiobarbituric acid derivatives and the like, and further, European Patent No. 568,993, US Patent No. 4,508,811 No. 5,227,227, JP-A-2001-125255, JP-A-11-271969, and the like can also be used. The usage-amount of a photosensitizer has the preferable range of 0.01-10.00 mass% in a cationically polymerizable composition.

  The cationic polymerizable composition of the present invention preferably contains a surfactant. As the surfactant, any of cationic, anionic, amphoteric and nonionic can be used.

  The emulsifier or dispersant is preferably an anionic surfactant or a polymer surfactant, and an anionic surfactant is particularly preferable. The activator for adjusting the surface tension of the cationic polymerizable composition is preferably a nonionic surfactant.

  Examples of the cationic surfactant include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts, and the like.

  Examples of anionic surfactants include fatty acid soap, N-acyl-N-methylglycine salt, N-acyl-N-methyl-β-alanine salt, N-acyl glutamate, alkyl ether carboxylate, acylated peptide , Alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, dialkyl sulfosuccinate, alkyl sulfoacetate, α-olefin sulfonate, N-acylmethyl taurine, sulfated oil, higher alcohol sulfate Salts, secondary higher alcohol sulfates, alkyl ether sulfates, secondary higher alcohol ethoxy sulfates, polyoxyethylene alkylphenyl ether sulfates, monoglyculates, fatty acid alkylolamide sulfates, alkyl ether phosphates Salt, alkyl phosphate ester salt and the like.

  Examples of amphoteric surfactants include carboxybetaine type, sulfobetaine type, aminocarboxylate, imidazolinium betaine and the like.

  Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene secondary alcohol ether, polyoxyethylene alkylphenyl ether (eg, Emulgen 911), polyoxyethylene sterol ether, polyoxyethylene lanolin derivative, polyoxyethylene Polyoxypropylene alkyl ether (for example, Newpol PE-62), polyoxyethylene glycerin fatty acid ester, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, polyethylene glycol fatty acid ester, Fatty acid monoglyceride, polyglycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol fatty acid ester, ® sugar fatty acid esters, fatty acid alkanolamides, polyoxyethylene fatty acid amides, polyoxyethylene alkyl amines, alkyl amine oxides, acetylene glycol, acetylene alcohol, and the like. In addition, examples of the surfactant include dispersants Demol SNB, MS, N, SSL, ST, and P (trade names) manufactured by Kao Corporation.

  When using these surfactants, they can be used singly or in combination of two or more, and can be added in the range of 0.001 to 1.0 mass% with respect to the total amount of the cationic polymerizable composition. The surface tension of the cationically polymerizable composition can be arbitrarily adjusted. When the cationic polymerizable composition is used as an inkjet ink, the surface tension of the ink is 22 to 38 mN / m, more preferably 24 to 35 mN / m. When implementing this invention, it is not limited to these. In order to maintain the long-term storage stability of the cationic polymerizable composition, an antiseptic and an antifungal agent may be added to the cationic polymerizable composition.

  Moreover, the following water-soluble resins can be used as the polymer surfactant, and the use of a cationically polymerizable composition as the ink is preferable from the viewpoint of ejection stability. As the water-soluble resin, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer are preferably used. Polymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer Etc. Other examples of the polymer surfactant include Jonkrill, an acrylic-styrene resin (Johnson Corporation). Two or more of these polymer surfactants can be used in combination.

  As addition amount with respect to the dispersion cationic polymerizable composition whole quantity of said each polymeric surfactant, 0.1-10 mass% is preferable, More preferably, it is 0.3-5 mass%. If the blending amount is less than 0.01% by mass, it is difficult to reduce the particle size of the suspension, and if it exceeds 10% by mass, the particle size of the suspension may increase or the suspension stability may decrease and gelation may occur. .

  In addition, it is preferable to contain 1 to 3% of water in the cationic polymerizable composition. The cationic polymerizable composition of the present invention is a solvent-free and active energy ray-curable composition comprising a cationic polymerizable compound, a cationic polymerization initiator, a coloring material, a dispersant, and a polymerization inhibitor. When the cationic polymerizable composition is irradiated with active energy rays, it generates cations from the cationic polymerization initiator, and initiates polymerization of the cationic polymerizable compound by the action of the cations to cure. During storage, water is present as an electron donor in the cationic polymerizable composition, so that when a cation is generated from the cationic polymerization initiator, it is trapped and functions as a polymerization inhibitor, and the gel of the cationic polymerizable composition Stable storage is possible. This cation scavenging effect improves as the amount of water added increases. Therefore, the cationic polymerizable composition of the present invention can contain a desired amount of water as long as the form of the solventless composition is not impaired. Since water is harmless, increasing the content in the cationically polymerizable composition does not cause environmental and sanitary inconveniences. In addition, since water contained in the cationic polymerizable composition evaporates from the cationic polymerizable composition due to heat accompanying irradiation of active energy rays during curing, the curability of the cationic polymerizable composition may be impaired. In particular, when forming a thin film or a printed image with the cationic polymerizable composition, it is advantageous because water is evaporated and removed more rapidly.

  The water used in the present invention is preferably ion-exchanged water or distilled water from which impurities such as inorganic salts have been removed. By using these waters, nozzle clogging caused by water-soluble impurities such as inorganic salts can be prevented.

[Curing method]
In the case of curing by irradiating with ultraviolet rays in a thin film state of 5 μm or less, the above cationic polymerizable composition of the present invention is not inhibited by polymerization and can be cured at high speed. In the ink jet recording method, such a thin film state is obtained when the droplet size is 10 to 20 pl or less, although it varies depending on the base material and the irradiation timing of ultraviolet rays.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[Synthesis of Cationic Polymerization Initiator 1]
20 ml of tin tetrachloride was added to a 500 ml three-necked flask, and 48.1 g of anisole was added with stirring. This solution was ice-cooled and 6.75 g of thionyl chloride was added dropwise while maintaining a temperature range of 10 to 15 ° C. At this time, the reaction became dark brown. Stirring was continued for 4 hours at room temperature, and 70 ml of water was added to the reaction solution. The oil layer was then removed and washed 3 times with diethyl ether. To this was added 18.4 g of KPF ₆ dissolved in 100 g of water, and the mixture was allowed to stand overnight. The oil layer was taken out again, washed with diethyl ether and dried under reduced pressure to obtain 32.3 g (yield 59.6%) of white powder of tris (4-methoxyphenyl) sulfonium hexafluorophosphate. The structure of this cationic polymerization initiator 1 was identified by infrared absorption spectrum, elemental analysis and NMR.

[Preparation of Cationic Polymerizable Compositions 1-7]
Cationic polymerizable compositions 1 to 7 having the compositions described in Table 1 below were prepared by a conventional method. The pigment, dispersant and polymerizable compound were dispersed in a bead mill for 3 hours, and then a cationic polymerization initiator, a surfactant and a basic compound were added, mixed and filtered to obtain a cationic polymerizable composition.

  The compounds used are shown below.

PR122: Pigment Red 122 (quinacridone pigment, acid value 4.4, amine value 4.5)
PR122 acid treatment: Pigment Red 122 surface acid-treated product (pigment obtained by acid-treating the surface of quinacridone pigment, acid value 4.7, amine value 6.1)
PB821: Ajisper PB821 manufactured by Ajinomoto Fine Techno Co., Ltd. (dispersant, acid value 30.4, amine value 10.2)
PB822: Ajimoto PB822 manufactured by Ajinomoto Fine Techno Co., Ltd. (dispersant, acid value 18.5, amine value 15.9)
S32000: Avecia Solsperse 32000 (dispersant, acid value 24.8, amine value 27.1)
OXT221: Aron Oxetane OXT221 (cationic polymerizable compound) manufactured by Toa Gosei Co., Ltd.
C2021P: Daicel's Celoxide 2021P (cationic polymerizable compound)
TAS1: Cationic polymerization initiator 1
SP152: SP152 manufactured by Asahi Kasei Corporation (monocation type, active ingredient 50%, cationic polymerization initiator)
UVI6992: Dow Chemical's UVI6992 (Cation polymerization initiator of dication and monocation mixed type, active ingredient 50%)
F1405: Dai Nippon Ink Co., Ltd. MegaFuck F1405 (surfactant)
TIPA: Triisopropanolamine (basic compound)
MTAC: Methyl trioctyl ammonium chloride (basic compound)

[Measurement and Evaluation of Characteristic Values of Cationic Polymerizable Composition]
The characteristic value of the cationic polymerizable composition was measured and evaluated by the following method. The results are shown in Table 2.

(Measurement of moisture content)
Immediately after preparing the cationic polymerizable composition, the water content was measured by the Karl Fischer method (automatic moisture measuring device AQV-2000 manufactured by Hiranuma Sangyo Co., Ltd.).

(Evaluation of storage stability)
The prepared cationic polymerizable composition is sealed in a glass bottle at a filling rate of 95% or more, subjected to an acceleration treatment for storage for 1 week at 70 ° C. in a light-shielding container, and then combined with the sample before storage, The average particle size, viscosity, satellite generation rate, intermittent discharge rate reduction rate, continuous discharge property and curing rate were evaluated by the method.

<Average particle size>
Immediately after the cationic polymerizable composition was diluted to a pigment concentration of about 0.5% by mass and then subjected to ultrasonic treatment for 5 minutes with an ultrasonic cleaner at 100 W and 28 kHz, a photon correlation method zeta manufactured by malvern was used. When measured with a sizer 1000HS, ZAve. Is the value of

<viscosity>
The viscosity was measured using a rheometer MCR300 (manufactured by Physica) under the conditions of 55 ° C. and Shear Rate = 1000 (1 / s).

<Satellite generation speed>
A piezo-type head capable of expressing 6 gradations by continuously discharging 5 drops of 4 pl of cationically polymerizable composition droplets heated to 55 ° C. at a driving frequency of 4 kHz and adjusting the driving voltage. While changing the drop speed, the minimum drop speed (m / s) at which satellites began to occur following the main drop was measured.

<Intermittent discharge speed reduction rate>
A piezo-type head capable of expressing 6 gradations by continuously discharging 5 drops of 4 pl of a cationic polymerizable composition heated to 55 ° C. per cycle at a driving frequency of 4 kHz, with a droplet speed of 6 m / s. The drive voltage was adjusted so that the first drop velocity reduction rate (%) immediately after stopping for 5 seconds after continuous ejection was measured.

<Continuous discharge>
A piezo-type head capable of expressing 6 gradations by continuously discharging 5 drops of 4 pl of a cationic polymerizable composition heated to 55 ° C. per cycle at a driving frequency of 4 kHz, with a droplet speed of 6 m / s. The drive voltage was adjusted so that the discharge was continued for 30 minutes, and the discharge state from the nozzles of each recording head was visually observed, and the continuous discharge property was evaluated according to the following criteria.

○: No nozzle missing even after 30 minutes of continuous discharge △: No nozzle missing due to continuous 30 minute discharge, but slightly satellite generated ×: No nozzle missing at several nozzles over 30 minutes of continuous ejection <Curing speed>
In an environment of 30 ° C. and 60% RH, 5 dots (drops) of 4 pl droplets of each cationic polymerizable composition heated to 55 ° C. by changing the piezo head speed from 50 to 800 mm / s in units of 50 mm / s. ) Discharge onto the YUPO substrate one by one, and after curing with an H bulb (1.5 kW light source), the surface of each dot is rubbed with a finger so that the cured cation polymerizable composition droplets do not peel off from the substrate. The head speed was determined and this was set as the curing speed (mm / s). The maximum film thickness was 2.0 to 2.5 μm.

  As is clear from the results in Table 2, by combining a basic compound as a polymerization inhibitor and a surface-treated pigment, both dispersion preservability (particle size) and dark reaction preservability (viscosity) can be achieved. When used as an inkjet application, it is possible to maintain ejection stability over a long period of time as described above, and because it has good curability with a thin film, high-speed printing with 4 pl droplets is possible. I understand that there is.

Claims (5)

In a cationically polymerizable composition containing a cationic polymerizable compound, a cationic polymerization initiator, a colorant, a dispersant, and a basic compound as a polymerization inhibitor, the colorant is surface-treated with one of polar, acid, and base. A cationically polymerizable composition characterized by being a pigment. 2. The cationically polymerizable composition according to claim 1, wherein the surface treating agent of the pigment is a sulfonic acid modified product of the pigment. The cationically polymerizable composition according to claim 1 or 2, wherein the dispersant is a polymer dispersant having a base. The cationically polymerizable composition according to any one of claims 1 to 3, wherein the acid value of the dispersant is larger than the amine value. A curing method, comprising curing the cationically polymerizable composition according to any one of claims 1 to 4 by irradiating with ultraviolet rays in a thin film state of 5 μm or less.