WO2023058194A1 - Inkjet ink composition, inkjet recording method, and inkjet recording system - Google Patents

Abstract

The present invention addresses the problem of providing: an inkjet ink composition that provides both flexibility and fastness for recorded matter and that suppresses reductions in the fastness during long-term storage; an inkjet recording method; and an inkjet recording system.　The inkjet ink composition according to the present invention is cured by heat or active-energy radiation, said inkjet ink composition characteristically comprising a polyfunctional compound A and an acrylate oligomer, wherein the degree of resonance stabilization when the polyfunctional compound A has become a radical is the same as or less than that for styrene, and the acrylate oligomer has at least three functional groups.

Description

Inkjet ink composition, inkjet recording method and inkjet recording system

The present invention relates to an inkjet ink composition, an inkjet recording method and an inkjet recording system. More specifically, the present invention relates to an inkjet ink composition that achieves both flexibility and fastness in recorded matter and suppresses deterioration of fastness during long-term storage.

For the purpose of protecting the circuit pattern, the printed circuit board is coated with ink and cured to form an insulating film (solder resist film). As a method for forming a solder resist film, for example, an inkjet method is known. Specifically, an inkjet ink (hereinafter also simply referred to as "ink") is applied, cured by light, and then cured by heat. I do.

In Patent Document 1, (A) a polybranched oligomer or polymer having an ethylenically unsaturated group, (B) a photopolymerization initiator, and (C) a thermosetting compound, a curable composition for inkjet printing has been disclosed. The cured product of the curable composition for inkjet printing has excellent heat resistance, toughness and adhesion to the substrate, but does not have excellent flexibility, so there is room for improvement when mounting it on a flexible device. there were. In addition, it has been difficult to suppress deterioration in fastness during long-term storage of the cured product.

Patent Document 2 discloses a technique for a curable composition for inkjet containing a urethane (meth)acrylate, a compound having a cyclic ether group, a photopolymerization initiator, and a heat curing agent. The cured product of the curable composition for inkjet is excellent in storage stability, heat resistance, insulation reliability, wettability to substrates, and migration resistance, but the cured product deteriorates in robustness during long-term storage. was difficult to suppress.

In addition, since the inks disclosed in Patent Documents 1 and 2 contain a thermosetting compound, the ink is easily cured when ejected at a high temperature, and sufficient ejection stability can be obtained. I had a problem that I couldn't

Patent Document 3 discloses a technique for an active energy ray-curable composition containing a monofunctional monomer composition (A) and a polyfunctional (meth)acrylic monomer (B) and having a ratio of rate constants within a specific range. disclosed. The active energy ray-curable composition is excellent in fast curing when using a light emitting diode (LED) as a light source, but since it is cured only by irradiation with an active energy ray, the active energy ray-curable composition There has been a demand for further improvement in the robustness of the cured product. In addition, it has been difficult to suppress deterioration in robustness of the cured product during long-term storage even with this technique.
In the present specification, "robustness" is used in the sense of "robustness", "scratch resistance (durability)", "abrasion resistance (durability)", "rubbing fastness", etc. .

JP 2019-178260 A JP 2016-147970 A JP 2019-104867 A

The present invention has been made in view of the above problems and circumstances, and the problem to be solved is to provide an inkjet ink composition that achieves both flexibility and fastness in a recorded matter and suppresses deterioration of fastness during long-term storage. An object of the present invention is to provide an inkjet recording method and an inkjet recording system.

In order to solve the above problems, the present inventors investigated the causes of the above problems, and found that the polyfunctional compound A, which has a resonance stabilization degree when it becomes a radical, is equal to or lower than that of styrene, and a functional group. The inventors have found that in a recorded matter obtained by curing an inkjet ink composition containing an acrylate oligomer having three or more acrylate oligomers, both flexibility and toughness are achieved, and a decrease in toughness during long-term storage is suppressed. reached.
That is, the above problems related to the present invention are solved by the following means.

1. An inkjet ink composition that is cured by active energy rays or heat,
Containing a polyfunctional compound A and an acrylate oligomer,
The degree of resonance stabilization when the polyfunctional compound A becomes a radical is equal to or less than that of styrene,
The inkjet ink composition, wherein the acrylate oligomer has 3 or more functional groups.

2. 2. The inkjet ink composition of item 1, wherein the Alfrey-Price Q value of the polyfunctional compound A is in the range of 0.70 to 1.00.

3. 3. The inkjet ink composition of item 1 or 2, wherein the inkjet ink composition has a shear viscosity of 40 to 400 mPa·s at 25° C. and a shear rate of 1000/sec.

4. 4. The inkjet ink composition according to any one of items 1 to 3, wherein the content of the polyfunctional compound A in the inkjet ink composition is in the range of 1 to 15% by mass. thing.

5. 5. The inkjet ink composition according to any one of items 1 to 4, wherein the content of the acrylate oligomer in the inkjet ink composition is in the range of 10 to 40% by mass.

6. Item 6. The inkjet ink composition of any one of Items 1 to 5, wherein the acrylate oligomer is a urethane acrylate oligomer.

7. 7. The inkjet ink composition of any one of paragraphs 1-6, wherein the acrylate oligomer is a hyperbranched acrylate oligomer.

8. Any one of items 1 to 7, further comprising a monomer, wherein the content of the polyfunctional compound B with respect to the total mass of the monomer is in the range of 90 to 100% by mass. The described inkjet ink composition.

9. Item 9. The inkjet ink composition according to any one of items 1 to 8, wherein the polyfunctional compound A is a methacrylate compound.

10. 10. The inkjet ink composition of any one of paragraphs 1 to 9, further comprising a gelling agent.

11. An inkjet recording method using an inkjet ink composition,
Using the inkjet ink composition according to any one of items 1 to 10, and
A step of ejecting the inkjet ink composition from an inkjet head and landing it on a recording medium;
An inkjet recording method, comprising a step of curing the inkjet ink composition that has landed on the recording medium with an active energy ray or heat.

12. An inkjet recording system using an inkjet ink composition,
Using the inkjet ink composition according to any one of items 1 to 10, and
an inkjet head for ejecting the inkjet ink composition;
an active energy ray irradiation unit that irradiates the inkjet ink composition that has landed on a recording medium with an active energy ray, and
An inkjet recording system comprising a heating section for heating the inkjet ink composition irradiated with the active energy ray.

By the above means of the present invention, it is possible to provide an inkjet ink composition, an inkjet recording method, and an inkjet recording system that achieve both flexibility and robustness in recorded matter and suppress deterioration in robustness during long-term storage.

Although the expression mechanism or action mechanism of the effects of the present invention has not been clarified, it is speculated as follows.

In general, active energy ray-curable resins contain oligomers and monomers having functional groups, and radicals and cations generated by irradiation with active energy rays are used as initiating species, and these react to polymerize and crosslink. Harden. It is believed that the inkjet ink composition of the present invention (hereinafter also simply referred to as “ink”) is cured by a radical polymerization reaction.

In the present invention, "polymerization" refers to a reaction of forming a new chemical bond to form a polymer, and "crosslinking" refers to connecting the polymer compounds formed by the polymerization reaction, A reaction that changes physical or chemical properties. The active energy ray-curable resin is cured by progressing polymerization and cross-linking, and by increasing the rate of polymerization and cross-linking, the robustness of the cured product of the active energy ray-curable resin is improved.

Since the acrylate oligomer according to the present invention has 3 or more functional groups, the polymerization reaction occurs more easily than the acrylate oligomer having 1 or 2 functional groups, and a molecule (polymer) having a high polymerization rate is formed at the initial stage of polymerization. Form. In radical polymerization, as the rate of polymerization rises, the viscosity of the system increases, and the diffusion rate of the growing radicals at the ends of the polymer decreases. ).

On the other hand, oxygen contained in the air is highly reactive with radicals and easily reacts with radical active species to form hydroperoxy radicals. Since this radical has poor reactivity with the monomer, the progress of the polymerization reaction is inhibited (polymerization inhibition). However, in the present invention, the rapid increase in viscosity of the system makes it difficult for oxygen to react with radical active species and to generate hydroperoxy radicals. As a result, the polymerization is less likely to be inhibited by oxygen, that is, the polymerization proceeds more easily, and the rapid curability of the ink and the robustness of the cured product are improved.

In addition, the polyfunctional compound A according to the present invention has a resonance stabilization degree equal to or lower than that of styrene when it becomes a radical. That is, the functional groups of the polyfunctional compound A according to the present invention are relatively reactive. Since it is low, some unreacted functional groups remain. As a result, the ink of the present invention is appropriately polymerized and crosslinked, and can achieve both sufficient flexibility and practically acceptable fastness in recorded matter.

Furthermore, the ink of the present invention undergoes polymerization and cross-linking by heating after irradiation with active energy rays, further improving the fastness of the recorded matter. However, since the functional groups of the polyfunctional compound A have relatively low reactivity as described above, some unreacted functional groups remain even after the heat reaction.

Generally, the cured products of active energy ray-curable resins tend to lose their durability during long-term storage due to hydrolysis, etc., which cuts the crosslinked structure. However, in the cured product of the ink of the present invention, while the crosslinked structure is cut by hydrolysis or the like, the above-mentioned unreacted functional groups form new bonds, so that the three-dimensional structure can be maintained, and the recorded material is durable. It is possible to suppress the decline in sexuality.

The inkjet ink composition of the present invention is an inkjet ink composition that is cured by actinic energy rays or heat, contains a polyfunctional compound A and an acrylate oligomer, and is resonance-stabilized when the polyfunctional compound A becomes a radical. The acrylate oligomer has a degree of polymerization equal to or lower than that of styrene, and the acrylate oligomer has 3 or more functional groups.
This feature is a technical feature common to or corresponding to the following embodiments.

In the present invention, the term "recorded material" refers to a material recorded on a recording medium using the ink of the present invention by the inkjet recording method described below, and the term "cured material" simply means the ink of the present invention. is a product obtained by curing the ink composition of , but the meaning is substantially the same.

As an embodiment of the present invention, the Alfrey-Price Q value of the polyfunctional compound A is preferably in the range of 0.70 to 1.00 from the viewpoint of effect expression.

From the viewpoint of obtaining sufficient ejection stability at 80° C. and improving the robustness of recorded matter, the shear viscosity of the inkjet ink composition at 25° C. and a shear rate of 1000/sec is in the range of 40 to 400 mPa·s. is preferably

From the viewpoint of improving the flexibility of recorded matter and the robustness in long-term storage, the content of the polyfunctional compound A in the inkjet ink composition is preferably within the range of 1 to 15% by mass.

From the viewpoint of improving the fastness of recorded matter, the content of the acrylate oligomer in the inkjet ink composition is preferably within the range of 10 to 40% by mass.

From the viewpoint of improving the fastness of recorded matter, the acrylate oligomer is preferably a urethane acrylate oligomer.

From the viewpoint of improving the fastness of recorded matter, the acrylate oligomer is preferably a hyperbranched acrylate oligomer.

From the viewpoint of improving the fastness of the recorded matter, it is preferable that a monomer is further contained and the content of the polyfunctional compound B is in the range of 90 to 100% by mass with respect to the total mass of the monomer.

From the viewpoint of improving the flexibility of recorded matter and the robustness in long-term storage, the polyfunctional compound A is preferably a methacrylate compound.

From the viewpoint of improving the pinning property of the ink and the robustness of the recorded matter, it is preferable to further contain a gelling agent.

Further, the inkjet recording method of the present invention comprises a step of using the inkjet ink composition of the present invention, discharging the inkjet ink composition from an inkjet head, and causing the ink composition to land on a recording medium; The method is characterized by comprising a step of curing the inkjet ink composition with an active energy ray and heat.

The inkjet recording system of the present invention uses the inkjet ink composition of the present invention, includes an inkjet head that ejects the inkjet ink composition, and active energy that irradiates the inkjet ink composition that has landed on a recording medium with an active energy ray. It is characterized by having a ray irradiation section and a heating section for heating the inkjet ink composition irradiated with the active energy ray.

The following is a detailed description of the present invention, its components, and the forms and modes for carrying out the present invention. In the present application, "-" is used to mean that the numerical values before and after it are included as the lower limit and the upper limit.

<<Overview of the inkjet ink composition of the present invention>>
The inkjet ink composition of the present invention (hereinafter also simply referred to as "ink") is an inkjet ink composition that is cured by actinic energy rays or heat, and contains a polyfunctional compound A and an acrylate oligomer. The resonance stabilization degree when the compound A becomes a radical is equal to or lower than that of styrene, and the acrylate oligomer has 3 or more functional groups.

"Curing by active energy rays or heat" means curing by irradiation with active energy rays or heating. In the ink of the present invention, the fastness of the recorded matter is improved by curing by heating after curing by irradiating the active energy ray. The ink of the present invention can be cured only by irradiation with an active energy ray or only by heating, but it is preferable to irradiate at least an active energy ray, and further heating improves the fastness of the recorded matter. From the viewpoint of improvement, it is more preferable.

In general, active energy ray-curable resins are cured by irradiation with active energy rays. More specifically, an oligomer and a monomer having a polymerizable functional group react with radicals and cations generated by irradiation with active energy rays to polymerize and crosslink to cure. In addition, since the active energy ray-curable resin containing a thermosetting agent is cured even by heating, the pencil hardness of the cured product is improved.

In particular, when using an active energy ray-curable resin as a solder resist ink, in addition to robustness, adhesion to the printed wiring board and heat resistance are required, so the ink often contains a thermosetting agent. Effective. However, ink containing a thermosetting agent has a high viscosity at high temperature, and there is a problem that sufficient ink ejection stability cannot be obtained under the temperature environment during ink ejection in the inkjet method.

The ink of the present invention contains a polyfunctional compound A (monomer) and an acrylate oligomer, and it is believed that the polyfunctional compound A and the acrylate oligomer are polymerized by radical polymerization and cured by forming a crosslinked structure. The reaction mechanism of radical polymerization is that a monomer (or oligomer) reacts with a radical active species generated from a small amount of polymerization initiator to generate a monomer (or oligomer) radical (initiation reaction), and this reaction occurs continuously ( growth reaction) polymer. Radical active species attack the ethylenically unsaturated bonds of monomers (or oligomers) to initiate polymerization.

Further, the ink of the present invention undergoes polymerization and cross-linking by further heating, but this polymerization reaction is caused by heating at a relatively high temperature for a long time, and is difficult to occur under the environment during ink ejection. It is considered that sufficient ejection stability can be obtained without increasing the viscosity of the ink.

<<Structure of the inkjet ink composition of the present invention>>
[1 Polyfunctional compound A]
The ink of the present invention contains the polyfunctional compound A whose resonance stabilization degree when converted to radicals is equal to or lower than that of styrene, thereby suppressing deterioration in the fastness of recorded matter during long-term storage.

The "polyfunctional compound" according to the present invention refers to a compound having two or more functional groups, and the "functional group" in the present invention refers to an atom or atomic group that causes reactivity of the compound. Say.
Further, in the present invention, the "resonance stabilization degree when becoming a radical" is used as an index indicating the degree of reactivity in the polymerization reaction of a polyfunctional compound.
Here, the "resonance stabilization degree when it becomes a radical" refers to the degree of stabilization in which the conjugated π-electron system has a lower energy than the isolated π-electron system due to the contribution of the resonance structure. It can be obtained by physical experiments, for example, measurement of radical lifetime and generation rate by an electron spin resonance apparatus (ESR), measurement of bond dissociation energy when radicals are generated, theoretical calculation, and the like.

In the present invention, the degree of resonance stabilization can be quantified as an Alfrey-Price Q value (hereinafter also simply referred to as “Q value”) described later, and the Q value of polyfunctional compound A is 1 or less. . In the present invention, the Q value of the polyfunctional compound A is preferably within the range of 0.70 to 1.00, more preferably within the range of 0.70 to 0.80. Details of the Q value will be described later.

The polyfunctional compound A according to the present invention is a monomer and has a weight average molecular weight of less than 1,000.
In the present invention, when two or more polyfunctional compounds with different Q values are used in combination, the polyfunctional compound with the highest Q value of 1 or less is considered to be the "polyfunctional compound A". Other polyfunctional compounds having a lower Q value than polyfunctional compound A will be referred to as "polyfunctional compound B". A detailed description of the polyfunctional compound B will be given later.

Since it is considered that the composition is cured by radical polymerization, the functional group preferably has an ethylenically unsaturated bond, and examples of the functional group include acryloyl group, methacryloyl group, and maleimide group. At least one of the functional groups of the polyfunctional compound A according to the present invention preferably has a methacryloyl group or a maleimide group, most preferably a methacryloyl group.

In the ink of the present invention, the content of the polyfunctional compound A is preferably in the range of 1 to 15% by mass, more preferably in the range of 2 to 10% by mass, relative to the total mass of the ink. . Within the above range, it is possible to improve the flexibility of the recorded matter and the robustness in long-term storage.

[1.1 Alfrey-Price Q value]
The Q value according to the present invention is an empirical parameter in the Alfrey-Price Q, e theory and is based on styrene (Q value: 1.0, e value: -0.8). The theory of Q and e can be found in general textbooks of polymer chemistry, for example, Takayuki Otsu, "Polymer Synthetic Chemistry" (Kagaku Dojin, 1979), pp. 116-120, Shohei Inoue, "Polymer Synthetic Chemistry" (Shohei Hanafusa, 2011) pp. 89-91, Takeshi Endo, “Synthesis of Polymers (Part 1)” (Kodansha, 2010) pp. 69-71, Tadaomi Nishikubo, “Basic Master Polymer Chemistry” (Ohmsha, 2011) pp. 182 , J. Brandrup, E. H. Immergut, E.; A. There is a description in Polymer Handbook 4th Edition, "Free Radical Copolymerization Reactivity Ratios" edited by Grulke, etc., and the Q value and e value of various monomers are determined based on styrene. Therefore, "equal to or less than styrene" means that the Q value is 1 or less.

The Q value is an index of how much stabilization can be achieved when a radical is added to a monomer, and the higher the value, the greater the resonance stabilization effect. The e value, which indicates the effect of polarity, is used as a measure of the electron density of the ethylenically unsaturated bond. The electron density of unsaturated bonds is small.

Therefore, the Q value can be adjusted by appropriately selecting the type of functional group and the molecular structure of the compound. In the ink, the Q value of the polyfunctional compound A is in the range of 0.70 to 1.00 from the viewpoint of moderate polymerization and cross-linking, and from the viewpoint of achieving both sufficient flexibility and practically no problem fastness of the recorded matter. and more preferably in the range of 0.70 to 0.80.

When the Q value of the polyfunctional compound A is 0.70 or more, the reactivity of the radical of the polyfunctional compound A is relatively lower than that of a compound having a Q value of less than 0.70. Compound A is less likely to be incorporated into the polymer chain, and unreacted functional groups tend to remain after film formation. In addition, when the Q value is 1.00 or less, the reactivity of the polyfunctional compound A is relatively higher than that of the polyfunctional compound having a Q value exceeding 1.00. Therefore, although unreacted functional groups remain, Due to its high reactivity, new bonds can be formed during long-term storage, so that the three-dimensional structure can be maintained in the cured product, improving the fastness of the recorded product.

The Q value according to the present invention can be obtained by theoretical calculation.
When theoretically calculating the Q value and e value, it is necessary to calculate calculation parameters obtained by optimizing the molecular structure of each monomer.
Calculation parameters were calculated with reference to Xinliang Yu, Xueye Wang & Bo Li. Prediction of the Qe parameters from radical structures. Colloid and Polymer Science. 2010 vol. 288, p. 951-958.

Table 1 of the above document describes the calculation results of the quantum chemical descriptor of each compound (monomer) when calculating the Q value. In the same manner as in the above literature, the quantum chemical descriptor of each compound is calculated by DFT calculation (Density Functional Theory), and each descriptor (q _MC2 , Q _AC2 , ΔE _βg ) was obtained and substituted into Equation 4 in the literature to calculate the Q value. Then, the calculation method was applied to each compound in this study to calculate the Q value. When the molecule has two or more functional groups, the calculation was performed assuming that only one of the functional groups is a radical.

Gaussian 16 (Revision B.01, M.J.Frisch, G.W.Trucks, H.B.Schlegel, G.E.Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, G. A. Petersson, H. Nakatsuji, X. Li, M. Caricato, A. V. Marenich, J. Bloino, B. G. Janesko, R. Gomperts, B. Mennucci, H. P. Hratchian, J. V. Ortiz, A. F. Izmaylov, J. L. Sonnenberg, D. Williams-Young, F. Ding, F. Lipparini, F. Egidi, J. Goings, B. Peng, A. Petrone, T. Henderson, D. Ranasinghe, V. G. Zakrzewski, J. Gao, N. Rega, G. Zheng, W. Liang, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, K. Throssell, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. J. Bearpark, J. J. Heyd, E. N. Brothers, K. N. Kudin, V. N. Staroverov, T. A. Keith, R Kobayashi, J. Normand, K. Raghavachari, A. P. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, J. M. Millam, M. Klene, C. Adamo , R. Cammi, J. W. Ochterski, R. L. Martin, K. Morokuma, O. Farkas, J. B. Foresman, and D. J. Fox, Gaussian, Inc., Wallingford CT, 2016.) Software can be used. In the present invention, DFT calculation (density functional theory) was used as the calculation method, UB3LYP was used as the functional, and 6-31G(d) was used as the basis function.

The polyfunctional compound A according to the present invention is not particularly limited as long as it has a Q value of 1 or less, but is preferably methacrylate or maleimide. Further, in the mutual relationship between the Q values of the above-described "polyfunctional compound A" and "polyfunctional compound B", when it corresponds to "polyfunctional compound A", as a specific example of "polyfunctional compound B" described later It may be the acrylate described.
Methacrylates and maleimides preferably used in the present invention are described below.

[1.2 Methacrylate]
Polyfunctional compound A according to the present invention is preferably a methacrylate having a methacryloyl group. By being a methacrylate, the ink of the present invention can be appropriately polymerized and crosslinked, and both sufficient flexibility and practically acceptable fastness of printed matter can be achieved. In addition, during long-term storage, unreacted functional groups form new bonds, so that the three-dimensional structure can be maintained and deterioration of the fastness of the recorded matter can be suppressed.

Examples of polyfunctional methacrylates are given below, among which those having a Q value of 1 or less correspond to the polyfunctional compound A in the present invention, and those having a Q value within the range of 0.70 to 1.00. is more preferred. Further, in the present invention, when two or more polyfunctional compounds with different Q values are used in combination, the polyfunctional compound with the highest Q value of 1 or less corresponds to the polyfunctional compound A, and other polyfunctional compounds The compound corresponds to polyfunctional compound B described later.

The polyfunctional methacrylate is not particularly limited as long as the Q value is within the above range.
Examples of polyfunctional methacrylates include triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, tripropylene glycol dimethacrylate, polypropylene glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexane. Diol dimethacrylate, 1,9-nonanediol dimethacrylate, neopentyl glycol dimethacrylate, tricyclodecane dimethanol dimethacrylate, PO adduct dimethacrylate of bisphenol A, neopentyl glycol hydroxypivalate dimethacrylate, polytetramethylene glycol dimethacrylate Bifunctional methacrylates such as methacrylate and tricyclodecanedimethanol dimethacrylate can be mentioned.

In addition, trimethylolpropane trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, ditrimethylolpropane tetramethacrylate, glycerin propoxytrimethacrylate, and pentaerythritol ethoxytetramethacrylate. and polyfunctional methacrylates containing

The methacrylate may be a modified product. Examples of modified methacrylates include ethylene oxide-modified trimethylolpropane trimethacrylate, ethylene oxide-modified pentaerythritol tetramethacrylate and the like, ethylene oxide-modified methacrylates including caprolactone-modified trimethylolpropane trimethacrylate and the like, and caprolactone-modified methacrylates. , caprolactam-modified methacrylates including caprolactam-modified dipentaerythritol hexamethacrylate and the like.

Examples of commercially available methacrylates having a Q value in the range of 0.70 to 1.00 include DCP, HD-N, 4G, M-40G, 3PG manufactured by Shin-Nakamura Chemical Co., Ltd., and M301 manufactured by Miwon. etc.

[1.3 Maleimide]
Polyfunctional compound A according to the present invention is preferably maleimide. By being maleimide, the ink of the present invention can be appropriately polymerized and crosslinked, and both sufficient flexibility and practically acceptable fastness of printed matter can be achieved.

Examples of polyfunctional maleimides are given below. Among them, those having a Q value of 1 or less correspond to the polyfunctional compound A in the present invention, and those having a Q value within the range of 0.70 to 1.00. is more preferred. Further, in the present invention, when two or more polyfunctional compounds with different Q values are used in combination, the polyfunctional compound with the highest Q value of 1 or less corresponds to the polyfunctional compound A, and other polyfunctional compounds The compound corresponds to polyfunctional compound B described later.

Examples of polyfunctional maleimides include 4,4′-diphenylmethanebismaleimide, phenylmethanemaleimide, bisphenol A bisphenyletherbismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethanebismaleimide. maleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, and the like.

Examples of commercially available products include BMI-1000, BMI-2300, BMI-4000, BMI-5100, and BMI-YMH manufactured by Daiwa Kasei Kogyo Co., Ltd., and BMI manufactured by K.I Kasei Co., Ltd. -70, BMI-80 and the like.

[2 Acrylate Oligomer]
Since the acrylate oligomer according to the present invention has 3 or more functional groups, the polymerization proceeds easily, and the fastness of the recorded matter is improved. The acryloyl group contained in the acrylate oligomer has an ethylenically unsaturated bond and is cured by radical polymerization.

The acrylate oligomer according to the present invention has 3 or more functional groups, and has an acryloyl group as a functional group. All functional groups may be acryloyl groups, or some may be different functional groups. The different functional group is not particularly limited, but is preferably a methacryloyl group from the viewpoint of facilitating the progress of polymerization and improving the fastness of recorded matter.

The number of functional groups in one molecule is not particularly limited as long as it is 3 or more, but it is preferably within the range of 4 to 30. Within the above range, the polymerization proceeds easily, and the fastness of the recorded matter is improved.

In the present invention, the term "oligomer" refers to a compound having a number of monomer bonds (degree of polymerization) within the range of 2-10 and a weight average molecular weight within the range of 1000-15000. In addition, the acrylate oligomer may contain only one type, or may contain two or more types.

In the ink of the present invention, the content of the acrylate oligomer is preferably within the range of 10 to 40% by mass, more preferably within the range of 10 to 30% by mass, relative to the total mass of the ink. By being within the above range, flexibility and robustness are further improved.

The acrylate oligomer is not particularly limited as long as it has 3 or more functional groups.
Examples of acrylate oligomers include urethane acrylate oligomers, polyester acrylate oligomers, epoxy acrylate oligomers, and the like. In addition, a hyperbranched acrylate oligomer having a characteristic structure is also included.

[2.1 Urethane acrylate oligomer]
The acrylate oligomer according to the invention is preferably a urethane acrylate oligomer. Since the urethane acrylate oligomer has a relatively high viscosity, polymerization proceeds easily and a crosslinked structure is easily formed by hydrogen bonding between urethane bonds. In addition, depending on the type of urethane acrylate oligomer, the fastness of the recorded matter is improved.

The urethane acrylate oligomer according to the present invention has a urethane bond and an acryloyl group generated by an addition reaction between an isocyanate group and a hydroxy group. In addition, urethane acrylate may contain only 1 type, and may contain 2 or more types.

A urethane acrylate oligomer can be obtained, for example, by reacting an isocyanate with an acrylic acid derivative having a hydroxy group.

Isocyanates used as raw materials for urethane acrylate oligomers include isophorone diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and diphenylmethane-4,4′-diisocyanate (MDI). , hydrogenated MDI, polymeric MDI, 1,5-naphthalene diisocyanate, norbornane diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), hydrogenated XDI, lysine diisocyanate, triphenylmethane triisocyanate, tris(isocyanatophenyl) thiophosphate , tetramethylxylene diisocyanate, and 1,6,10-undecane triisocyanate.

Isocyanates used as raw materials for urethane acrylate oligomers include those obtained by reacting polyols such as ethylene glycol, glycerin, sorbitol, trimethylolpropane, propylene glycol, carbonate diols, polyether diols, polyester diols, and polycaprolactone diols with excess isocyanate. A chain-extended isocyanate compound may be used.

Examples of acrylic acid derivatives having a hydroxy group that serve as raw materials for urethane acrylate oligomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, and 2-hydroxybutyl acrylate, Dihydric alcohol monoacrylates such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, polyethylene glycol, trimethylolethane, trimethylolpropane, glycerin, etc. trihydric alcohol monoacrylate or diacrylate, epoxy acrylate such as bisphenol A type epoxy acrylate, and the like.

The urethane acrylate oligomer preferably does not have a carboxy group. By using the urethane acrylate oligomer having no carboxy group, the insulation of the recorded matter is improved.

The number of functional groups of acryloyl groups contained in one molecule of the urethane acrylate oligomer is not particularly limited as long as it is 3 or more, but it is preferably in the range of 3 to 20, more preferably in the range of 3 to 15. is more preferable, and the range of 3 to 10 is even more preferable.

The weight average molecular weight of the urethane acrylate oligomer is preferably within the range of 1000-15000. Within the above range, the ink of the present invention can have sufficient ejection stability.

Also, in the production of the ink of the present invention, the urethane acrylate oligomer may contain a diluent. The type of diluent is not particularly limited, and examples thereof include acrylate monomers and solvents. From the viewpoint of reducing volatile organic compounds (VOC), acrylate monomers are preferable.

Examples of commercially available urethane acrylate oligomers include M-1100, M-1200, M-1210, M-1600 (manufactured by Toagosei Co., Ltd.), EBECRYL 230, EBECRYL 270, EBECRYL 4858, EBECRYL 8402, EBECRYL 8804, ＥＢＥＣＲＹＬ　８８０３、ＥＢＥＣＲＹＬ　８８０７、ＥＢＥＣＲＹＬ　９２６０、ＥＢＥＣＲＹＬ　１２９０、ＥＢＥＣＲＹＬ　５１２９、ＥＢＥＣＲＹＬ　４８４２、ＥＢＥＣＲＹＬ　２１０、ＥＢＥＣＲＹＬ　４８２７、ＥＢＥＣＲＹＬ　６７００、ＥＢＥＣＲＹＬ　２２０、ＥＢＥＣＲＹＬ　２２２０（以上、ダイセル・オルネクス社製、なお、「ＥＢＥＣＲＹＬ」は同社の登録Trademark), Artresin UN-9000H, Artresin UN-9000A, Artresin UN-7100, Artresin UN-1255, Artresin UN-330, Artresin UN-3320HB, Artresin UN-1200TPK, Artresin SH-500B (The above are manufactured by Neagari Kogyo Co., Ltd., and “Art Resin” is a registered trademark of the company), U-122P, U-108A, U-340P, U-4HA, U-6HA, U-324A, U-15HA, UA -5201P, UA-W2A, U-1084A, U-6LPA, U-2HA, U-2PHA, UA-4100, UA-7100, UA-4200, UA-4400, UA-340P, U-3HA, UA-7200 , U-2061BA, U-10H, U-122A, U-340A, U-108, U-6H, UA-4000 (manufactured by Shin-Nakamura Chemical Co., Ltd.), and AH-600, AT-600, UA -306H, AI-600, UA-101T, UA-101I, UA-306T, UA-306I (manufactured by Kyoeisha Chemical Co., Ltd.), CN959, CN969NS, CN996NS, CN2920, CN9009, CN9011, CN8885, CN8885NS, CN989, CN989NS , CN9023, CN9290, CN968NS, CN972, CN975NS, CN992 (manufactured by Sartomer), BR-144B, BR-771F, BRC-843 (manufactured by DYMAX) and the like.

In the present invention, the content of the urethane acrylate oligomer is not particularly limited, but it is preferably in the range of 1 to 40% by mass, more preferably in the range of 5 to 30% by mass, based on the total mass of the ink. is more preferable, and more preferably within the range of 10 to 20% by mass.

[2.2 Hyperbranched acrylate oligomer]
The acrylic oligomer according to the invention is preferably a hyperbranched acrylate oligomer. Having a hyperbranched (hyperbranched) structure facilitates polymerization, facilitates formation of a crosslinked structure, and improves the fastness of recorded matter.

In the present invention, the term "hyperbranched structure" refers to a dendritic compound having many branch points in one molecule, for example, an AB ₂ type molecule having a total of 3 or more of two types of substituents in one molecule. or the A ₂ +B ₃ method, which is a condensation reaction between two molecules (A ₂ type, B ₃ type).

Therefore, the hyperbranched structure in the present invention includes dendrimer structures (dendritic structures), star structures and graft structures.

Examples of commercially available hyperbranched acrylate oligomers include V#1000 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), CN2302, CN2303, CN2304 (manufactured by Sartomer), SP1106 (manufactured by Miwon) 6361-100. , 6363 (manufactured by Choko Kagaku Kogyo Co., Ltd.) and the like. These may be used individually by 1 type, and may use 2 or more types together.

[3 Monomer]
The ink of the invention preferably further contains a monomer.
The monomer according to the present invention may be any monomer that causes polymerization or cross-linking reaction upon irradiation with active energy rays. Also, the compound may be a compound that also has the property of causing a polymerization reaction by heating, but it is preferable to contain it to the extent that sufficient ink ejection stability can be obtained. Monomers preferably include both monofunctional and polyfunctional compounds. The content of the polyfunctional compound B with respect to the total weight of the monomers is preferably within the range of 90 to 100% by weight, more preferably 100% by weight. By increasing the content of the polyfunctional compound B, the fastness of the recorded matter is further improved.

In the present invention, the term "monomer" refers to a compound that is a starting material for forming a polymer in a polymerization reaction and has a weight average molecular weight of less than 1,000. functional compound” and “polyfunctional compound B”. Therefore, the polyfunctional compound A is not included in the monomers according to the invention. In addition, each of the monofunctional compound and the polyfunctional compound B may contain only one type, or may contain two or more types.

In the present invention, "monofunctional compound" refers to a compound having one functional group among the above monomers.
Since a monofunctional compound can be used as a reactive diluent, the viscosity of the ink can be adjusted by containing a monofunctional compound having a relatively low viscosity.

In addition, in the present invention, "polyfunctional compound B" refers to a compound having two or more functional groups among the above monomers. In addition, when the ink of the present invention uses two or more polyfunctional compounds with different Q values in combination, other polyfunctional Refers to compounds.

In particular, the ink of the present invention further contains, as the polyfunctional compound B, a compound with a Q value lower than that of the polyfunctional compound A, that is, with high reactivity, so that polymerization and cross-linking proceed appropriately. Therefore, the fast curing property of the ink and the fastness of the recorded matter are improved.

The functional group is not particularly limited, but from the viewpoint of curing by radical polymerization, an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, a vinyl ester group, etc. having an ethylenically unsaturated bond can be mentioned.

The above-mentioned monofunctional compound and polyfunctional compound B having functional groups are preferably unsaturated carboxylic acid ester compounds, more preferably acrylates.

Examples of monofunctional acrylates include isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isomyrstyl acrylate, isostearyl acrylate, 2-ethylhexyl-diglycol acrylate, 2-hydroxybutyl acrylate, 2-acrylate loyloxyethyl hexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, o-phenylphenol acrylate, 2-hydroxy-3-phenoxypropyl acrylate, Cumylphenoxyl ethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-acryloyloxyethyl succinate, 2- acryloyloxyethyl phthalate, 2-acryloyloxyethyl-2-hydroxyethyl-phthalate, and t-butylcyclohexyl acrylate.

Examples of polyfunctional acrylates are given below. In the ink of the present invention, the polyfunctional compound having a Q value of 1 or less and having the highest Q value compared to other polyfunctional compounds used in combination may be the polyfunctional compound described above. It corresponds to polyfunctional compound A, and other polyfunctional compounds correspond to polyfunctional compound B.
Examples of bifunctional acrylates include triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate. Acrylates, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, PO adduct diacrylate of bisphenol A, neopentyl glycol hydroxypivalate diacrylate, polytetramethylene glycol diacrylate , and tricyclodecane dimethanol diacrylate.

Examples of tri- or more functional acrylates include trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxy triacrylate, and pentaerythritol ethoxy tetraacrylate. is mentioned.

Of the above acrylates, phenoxyethyl acrylate, o-phenylphenol acrylate, and 2-hydroxy-3-phenoxypropyl acrylate are preferred from the viewpoint of suppressing curing shrinkage.

From the viewpoint of rapid curing, neopentyl glycol diacrylate, tricyclodecanedimethanol diacrylate, PO adduct diacrylate of bisphenol A, and neopentyl glycol hydroxypivalate diacrylate are preferable.

Incidentally, the acrylate may be a modified product.
Examples of modified acrylates include ethylene oxide-modified trimethylolpropane triacrylate, ethylene oxide-modified pentaerythritol tetraacrylate, ethylene oxide-modified trimethylolpropane triacrylate, and propylene oxide-modified pentaerythritol tetraacrylate. and the like, caprolactone-modified acrylates including caprolactone-modified trimethylolpropane triacrylate, and caprolactam-modified acrylates including caprolactam-modified dipentaerythritol hexaacrylate.

In the ink of the present invention, the monomer content is preferably in the range of 40 to 90% by mass, more preferably in the range of 60 to 85% by mass, relative to the total mass of the ink. By being within the above range, ejection stability can be obtained.

Among them, the content of the polyfunctional compound B is preferably in the range of 90 to 100% by mass with respect to the total mass of the monomer (that is, the total mass of the monofunctional compound and the polyfunctional compound B), and 100 % by mass is more preferred. When the content of the polyfunctional compound B, which has a lower Q value than the polyfunctional compound A described above, that is, a content of the highly reactive polyfunctional compound B, is within the above range, the fastness of the recorded matter is further improved.

[4 Polymerization initiator]
The ink of the invention can be cured by radical polymerization or ionic polymerization, but in the invention, it is preferable to use a radical polymerization initiator as the polymerization initiator.
The ink of the present invention may contain only one polymerization initiator, or may contain two or more polymerization initiators.

Examples of radical polymerization initiators include α-cleavage radical polymerization initiators (also referred to as “Norrish I type polymerization initiators”) and hydrogen abstraction type radical polymerization initiators (also referred to as “Norrish II type polymerization initiators”). be done.

The content of the α-cleavage type radical polymerization initiator is preferably in the range of 0.3 to 6% by mass with respect to the total mass of the ink of the present invention. Also, the content of the hydrogen abstraction type radical polymerization initiator is preferably in the range of 0.5 to 10% by mass with respect to the total mass of the ink of the present invention.

An α-cleaving radical polymerization initiator is an initiator that cleaves after photoexcitation to give the initiating radical directly.
Further, the hydrogen abstraction type radical polymerization initiator is a photopolymerization initiator that is activated by an active energy ray (for example, ultraviolet rays) and generates free radicals by hydrogen abstraction from the second compound. become the starting free radicals. This second compound is called a polymerization synergist or co-initiator.
Both α-cleavage type radical polymerization initiators and hydrogen abstraction type radical polymerization initiators can be used alone or in combination in the present invention.

Examples of α-cleavage radical polymerization initiators include acetophenone-based initiators, benzoin-based initiators, acylphosphine oxide-based initiators, benzyl and methylphenylglyoxyester.

Examples of acetophenone-based initiators include diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethylketal, 1-(4-isopropylphenyl)-2-hydroxy-2- Methylpropan-1-one, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl-phenylketone, 2-methyl-2-morpholino(4-thiomethylphenyl) Propan-1-one and 2-benzyl-2-dimethylamino 1-(4-morpholinophenyl)-butanone.

Examples of benzoin-based initiators include benzoin, benzoin methyl ether and benzoin isopropyl ether.
Examples of acylphosphine oxide initiators include 2,4,6-trimethylbenzoindiphenylphosphine oxide and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide.

Examples of hydrogen abstraction type radical initiators include benzophenone-based initiators, thioxanthone-based initiators, aminobenzophenone-based initiators, 10-butyl-2-chloroacridone, 2-ethylanthraquinone, 9,10- Phenanthrenequinone and camphorquinone are included.

Examples of benzophenone-based initiators include benzophenone, methyl-4-phenylbenzophenone o-benzoylbenzoate, 4,4′-dichlorobenzophenone, hydroxybenzophenone, 4-benzoyl-4′-methyl-diphenylsulfide, acrylated benzophenone. , 3,3′,4,4′-tetra(t-butylperoxycarbonyl)benzophenone and 3,3′-dimethyl-4-methoxybenzophenone.
Examples of thioxanthone-based initiators include 2-isopropylthioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone and 2,4-dichlorothioxanthone.

Examples of aminobenzophenone initiators include Michler's ketone and 4,4'-diethylaminobenzophenone.

[5 Polymerization inhibitor]
The ink of the present invention preferably further contains a polymerization inhibitor. By containing a polymerization inhibitor, adhesion between a plurality of curable compounds can be reduced.
In the present invention, the term “polymerization inhibitor” includes all compounds added to inhibit polymerization reaction during preparation of ink containing a polymerizable compound or during storage after preparation.

In the present invention, various conventionally known polymerization inhibitors can be used. Examples of the polymerization inhibitor include N-oxyl polymerization inhibitors, phenol polymerization inhibitors containing an It is more preferable to contain any one of the polymerization inhibitors having two or more aromatic rings from the viewpoint of effect expression.

Among these, it is more preferable to contain an N-oxyl-based polymerization inhibitor from the viewpoint of adhesion to the printed wiring board.
In the ink of the present invention, the content of the polymerization inhibitor is preferably within the range of 0.05 to 0.5% by mass with respect to the total mass of the ink.

[5.1 N-oxyl polymerization inhibitor]
Examples of N-oxyl polymerization inhibitors include 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), 4-hydroxy-2,2,6,6-tetramethyl- piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4- acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, Irgastab (registered trademark) UV10 (manufactured by BASF) and the like.

[5.2 Phenolic polymerization inhibitor]
Examples of phenolic polymerization inhibitors include 2,6-di-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl 4,6-dimethylphenol, 2,6-di-tert- Butyl-4-methylphenol, 2,4,6-tri-tert-butylphenol, 2,6-di-t-butyl-p-cresol (butylated hydroxytoluene: BHT), 4-methoxyphenol, 2-methoxy- 4-methylphenol and the like.

[5.3 Quinone Polymerization Inhibitor]
Examples of quinone polymerization inhibitors include hydroquinone, methoxyhydroquinone, benzoquinone, 1,4-naphthoquinone, p-tert-butylcatechol and the like.

[5.4 Amine Polymerization Inhibitor]
Examples of amine polymerization inhibitors include alkylated diphenylamine, N,N'-diphenyl-p-phenylenediamine and phenothiazine.

[5.5 Other polymerization inhibitors]
Other examples include copper dithiocarbamate-based polymerization inhibitors such as copper dimethyldithiocarbamate, copper diethyldithiocarbamate, and copper dibutyldithiocarbamate.

These may contain only one type, or may contain two or more types.
Among these, N-oxyl-based and quinone-based polymerization inhibitors are preferable, and 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), 2,6-di-t -Butyl-p-cresol (butylated hydroxytoluene: BHT), 2,4-di-tert-butylphenol, and naphthoquinone as a polymerization inhibitor having two or more aromatic rings are preferred.

[6 Gelling agent]
The ink of the present invention preferably further contains a gelling agent.
By containing the gelling agent, the ink on the recording medium can be temporarily fixed (pinned) in a gel state, and the wetting and spreading of the ink can be suppressed. And the fastness of the recorded matter is improved.

The gelling agent preferably crystallizes at a temperature below the gelling temperature of the ink.
The term “gelling temperature” refers to the temperature at which the gelling agent undergoes a phase transition from sol to gel and the viscosity of the composition suddenly changes when the composition that has been solified or liquefied by heating is cooled.
Specifically, the solified or liquefied composition is cooled while measuring the viscosity with a viscoelasticity measuring device (e.g., MCR300, manufactured by Anton Paar), and the temperature at which the viscosity suddenly increases is It can be the gelling temperature of the composition.

In the present invention, when the gelling agent is crystallized in the ink, a polymerizable compound (polyfunctional compound A, acrylate oligomer, polymerization of a monomer, etc.) is added to the three-dimensional space formed by the plate-like crystallized gelling agent. A so-called card house structure is formed in which the compound involved in In order to form this card house structure, it is preferable that the polymerizable compound dissolved in the ink and the gelling agent are compatible with each other.

Examples of gelling agents suitable for forming card house structures include aliphatic ketones, aliphatic esters, petroleum-based waxes, vegetable-based waxes, animal-based waxes, mineral-based waxes, hydrogenated castor oil, modified waxes, higher fatty acids, Higher alcohols, hydroxystearic acid, fatty acid amides including N-substituted fatty acid amides and special fatty acid amides, higher amines, esters of sucrose fatty acids, synthetic waxes, dibenzylidene sorbitol, dimer acid and dimer diols.

Among them, aliphatic ketones, aliphatic esters, higher fatty acids, and higher alcohols having a hydrocarbon group of 9 to 25 carbon atoms are preferred from the viewpoint of improving pinning properties.
Only one type of gelling agent may be contained, or two or more types may be contained.

[6.1 Aliphatic Ketones]
Examples of aliphatic ketones include dilignoceryl ketone, dibehenyl ketone, distearyl ketone, dieicosil ketone, dipalmityl ketone, dilauryl ketone, dimyristyl ketone, myristyl palmityl ketone and palmityl stearyl ketone. mentioned.

[6.2 Aliphatic Ester]
Examples of aliphatic esters include fatty acid esters of monoalcohols such as behenyl behenate, icosyl icosanoate and oleyl palmitate; glycerin fatty acid esters, sorbitan fatty acid esters, propylene glycol fatty acid esters, ethylene glycol fatty acid esters and polyoxyethylene fatty acid esters. fatty acid esters of polyhydric alcohols such as

Examples of commercially available products of the above-mentioned aliphatic esters include the EMALEX (registered trademark) series manufactured by Nippon Emulsion Co., Ltd., and the Rikemal (registered trademark) series and Poem (registered trademark) series manufactured by Riken Vitamin.

[6.3 Higher Fatty Acid]
Examples of higher fatty acids include behenic acid, arachidic acid, stearic acid, palmitic acid, myristic acid, lauric acid, oleic acid, and erucic acid.

[6.4 Higher alcohol]
Examples of higher alcohols include stearyl alcohol and behenyl alcohol.

[6.5 Suitable Gelling Agents]
In the present invention, the gelling agent is particularly preferably an aliphatic ketone represented by general formula (G1) below or an aliphatic ester represented by general formula (G2) below.

General formula (G1): R ₁ —CO—R ₂

(In the general formula (G1), R ₁ and R ₂ each independently represent an alkyl group containing a linear portion having 12 to 26 carbon atoms and which may contain a branch. R ₁ and R ₂ may be the same or different.)

General formula (G2): R ₃ —COO—R ₄

(In the general formula (G2), R ₃ and R ₄ each independently represent an alkyl group containing a linear portion having 12 to 26 carbon atoms and which may contain a branch. R ₃ and _R4 may be the same or different.)

In the general formulas (G1) and (G2), the linear or branched hydrocarbon group has 12 or more carbon atoms, so that the aliphatic ketone represented by the general formula (G1) or the general formula (G2 ) is more crystalline and more space is created in the card house structure. Therefore, the polymerizable compound is likely to be sufficiently included in the space, and the pinning property of the ink is improved.

Further, when the number of carbon atoms in the linear or branched hydrocarbon group is 26 or less, the aliphatic ketone represented by the general formula (G1) or the aliphatic ester represented by the general formula (G2) The melting point of the ink does not rise excessively, that is, the melting point can be set to a temperature that is easy to handle, and there is no need to excessively heat the ink when ejecting the ink.

Examples of aliphatic ketones represented by the general formula (G1) include dilignoceryl ketones (carbon atoms: 23, 24), dibehenyl ketones (carbon atoms: 21, 22), distearyl ketones (carbon atoms: 17 , 18), dieicosilketone (carbon number: 19, 20), dipalmityl ketone (carbon number: 15, 16), dimyristyl ketone (carbon number: 13, 14), dilauryl ketone (carbon number: 11 , 12), lauryl myristyl ketone (carbon number: 11, 14), lauryl palmityl ketone (carbon number: 11, 16), myristyl palmityl ketone (carbon number: 13, 16), myristyl stearyl ketone (carbon number: 13 , 18), myristyl behenyl ketone (carbon number: 13, 22), palmityl stearyl ketone (carbon number: 15, 18), palmityl behenyl ketone (carbon number: 15, 22) and stearyl behenyl ketone (carbon number: 17 , 22). The number of carbon atoms in parentheses represents the number of carbon atoms in each of the two hydrocarbon groups separated by the carbonyl group.

Examples of commercially available aliphatic ketones represented by the general formula (G1) include 18-Pentatriacontanon and Hentriacontan-16-on manufactured by Alfa Aeser, and Kao Wax T-1 manufactured by Kao Corporation.

Examples of the aliphatic ester represented by the general formula (G2) include behenyl behenate (carbon number: 21, 22), icosyl icosanoate (carbon number: 19, 20), stearyl stearate (carbon number: 17, 18), palmityl stearate (carbon number: 16, 17), lauryl stearate (carbon number: 12, 17), cetyl palmitate (carbon number: 6, 15), stearyl palmitate (carbon number: 15, 18) , myristyl myristate (carbon number: 13, 14), cetyl myristate (carbon number: 13, 16), octyldodecyl myristate (carbon number: 13, 20), stearyl oleate (carbon number: 17, 18), stearyl erucate (carbon number: 18, 21), stearyl linoleate (carbon number: 17, 18), behenyl oleate (carbon number: 18, 22) and arachidyl linoleate (carbon number: 17, 20) . The number of carbon atoms in parentheses represents the number of carbon atoms in each of the two hydrocarbon groups separated by the ester group.

Examples of commercially available aliphatic esters represented by the general formula (G2) include Unistar (registered trademark) M-2222SL and Spermaceti manufactured by NOF Corporation, and Excepar (registered trademark) SS and Excepar (registered trademark) manufactured by Kao Corporation. Trademark) MY-M, EMALEX (registered trademark) CC-18 and EMALEX (registered trademark) CC-10 manufactured by Nihon Emulsion Co., Ltd., and Amleps (registered trademark) PC manufactured by KOKYU ALCOHOL KOGYO CO., LTD.

[6.6 Content of gelling agent]
In the present invention, the content of the gelling agent is preferably in the range of 1 to 10% by weight with respect to the total weight of the ink.

[7 Other components]
[7.1 Surfactant]
The ink of the invention may further contain a surfactant, if desired.
Examples of surfactants include anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates and fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols and polyoxy Examples include nonionic surfactants such as ethylene/polyoxypropylene block copolymers, cationic surfactants such as alkylamine salts and quaternary ammonium salts, and silicone-based and fluorine-based surfactants.

[7.2 Colorant]
The ink of the present invention may further contain a colorant as needed.
The colorant may be a pigment or a dye, but is preferably a pigment from the viewpoint of good dispersibility in ink constituents and excellent weather resistance.
The pigment is not particularly limited, and examples thereof include organic pigments or inorganic pigments having the following numbers described in the Color Index.

The ink of the present invention may contain only one type of coloring agent, or may contain two or more types of coloring agents, and may be mixed to a desired color.
The content of the colorant is preferably in the range of 0.1 to 20% by mass, more preferably in the range of 0.2 to 10% by mass, relative to the total mass of the ink.

(pigment)
《Red or magenta pigment》
Examples of red or magenta pigments are Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53 : 1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144 , 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Pigments selected from Orange 13, 16, 20 and 36, mixtures thereof, and the like.

《Blue or Cyan Pigment》
Examples of blue or cyan pigments are Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17:1, 22, 27, 28, 29, 36 , 60 or a mixture thereof.

《Green Pigment》
Examples of green pigments include pigments selected from Pigment Green 7, 26, 36, 50 or mixtures thereof.

《Yellow Pigment》
Examples of yellow pigments include Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137 , 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193 or a mixture thereof.

《Black Pigment》
Examples of black pigments include pigments selected from Pigment Black 7, 28 and 26, mixtures thereof, and the like.

《Examples of commercially available pigments》
Examples of commercially available pigments include Black Pigment (manufactured by Mikuni), Chromo Fine Yellow 2080, 5900, 5930, AF-1300, 2700L, Chromo Fine Orange 3700L, 6730, Chromo Fine Scarlet 6750, Chromo Fine Magenta 6880, 6886. , 6891N, 6790, 6887, Chromofine Violet RE, Chromofine Red 6820, 6830, Chromofine Blue HS-3, 5187, 5108, 5197, 5085N, SR-5020, 5026, 5050, 4920, 4927, 4937, 4824, 4933GN-EP, 4940, 4973, 5205, 5208, 5214, 5221, 5000P, Chromo Fine Green 2GN, 2GO, 2G-550D, 5310, 5370, 6830, Chromo Fine Black A-1103, Seika Fast Yellow 10GH, A-3 , 2035, 2054, 2200, 2270, 2300, 2400 (B), 2500, 2600, ZAY-260, 2700 (B), 2770, Seika Fast Red 8040, C405 (F), CA120, LR-116, 1531B, 8060R , 1547, ZAW-262, 1537B, GY, 4R-4016, 3820, 3891, ZA-215, Seika Fast Carmin 6B1476T-7, 1483LT, 3840, 3870, Seika Fast Bordeaux 10B-430, Seika Light Rose R40, Seika Light Violet B800, 7805, Seika Fast Maroon 460N, Seika Fast Orange 900, 2900, Seika Light Blue C718, A612, Cyanine Blue 4933M, 4933GN-EP, 4940, 4973 (manufactured by Dainichi Seika Kogyo Co., Ltd., "Chromofine ” is a registered trademark of the company); 310, 336, 337, 338, 346, KET Blue 101, 102, 103, 104, 105, 106, 111, 118, 124, KET Green 201 (manufactured by DIC); Colortex Yellow 301, 314, 315, 316 , P-624, 314, U10GN, U3GN, UNN, UA-414, U263, Finecol Yellow T-13, T-05, Pigment Yellow 1705, Colortex Orange 202, Colortex Red 101, 103, 115, 116, D3B, P-625 , 102, H-1024, 105C, UFN, UCN, UBN, U3BN, URN, UGN, UG276, U456, U457, 105C, USN, Colortex Maroon601, Colortex BrownB610N, Colortex Violet600, Pigment Red76, 1515B Color 122, Color , 519, A818, P-908, 510, Colortex Green 402, 403, Colortex Black 702, U905 (manufactured by Sanyo Pigment Co., Ltd., "Colortex" and "Finecol" are registered trademarks of the company); Lionol Yellow 1405G, Lionol Blue FG7330, FG7350, FG7400G, FG7405G, ES, ESP-S (manufactured by Toyo Ink Co., Ltd., "Lionol" is a registered trademark of the same company), Toner Magenta E02, Permanent Rubin F6B, Toner Yellow HG, Permanent Yellow GG-02, Hostapeam BlueB2G (manufactured by Hoechst Industries); Novoperm P-HG, Hostaperm Pink E, Hostaperm Blue B2G (manufactured by Clariant, where "Novoperm" and "Hostaperm" are registered trademarks of the same company); carbon black #2600, #2400, #2350, #2200, #1000, #990, #980, #970, #960, #950, #850, MCF88, #750, #650, MA600, MA7, MA8, MA11, MA100, MA100R, MA77, #52, #50, #47, #45, #45L, #40, #33, #32, #30, #25, #20, #10, #5, #44, CF9 (Mitsubishi Chemical made) and the like.

《Pigment Dispersion》
The pigment can be dispersed by using, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, and paint shaker.

Dispersion of the pigment is such that the volume average particle diameter of the pigment particles is preferably in the range of 0.08 to 0.5 μm, the maximum particle diameter is preferably in the range of 0.3 to 10 μm, more preferably 0.3 to 3 μm. is preferably within the range of
Dispersion of the pigment is adjusted by selection of the pigment, dispersant and dispersion medium, dispersion conditions, filtration conditions, and the like.

《Dispersant》
The ink of the present invention may further contain a dispersant in order to enhance dispersibility of the pigment.
Examples of dispersants include carboxylic acid esters having hydroxy groups, salts of long-chain polyaminoamides and high-molecular-weight acid esters, salts of high-molecular-weight polycarboxylic acids, salts of long-chain polyaminoamides and polar acid esters, high-molecular-weight unsaturated acid esters, polymer copolymers, modified polyurethanes, modified polyacrylates, polyether ester type anionic surfactants, naphthalene sulfonic acid formalin condensate salts, aromatic sulfonic acid formalin condensate salts, polyoxyethylene alkyl phosphate esters, polyoxyethylene nonylphenyl ether, stearylamine acetate, and the like. Examples of commercially available dispersants include Solsperse (registered trademark) series manufactured by Avecia, PB series manufactured by Ajinomoto Fine-Techno Co., Inc., and the like.

《Dispersing aid》
The ink of the present invention may further contain a dispersing aid, if desired.
A dispersing aid may be selected according to the pigment.
The total content of the dispersant and dispersing aid is preferably in the range of 1 to 50% by weight with respect to the total weight of the pigment.

《Dispersion medium》
The ink of the present invention may further contain a dispersing medium for dispersing the pigment, if necessary.
The ink of the present invention may contain a solvent as a dispersion medium, but in order to suppress the solvent from remaining in the formed image, the aforementioned monomers (especially monomers with low viscosity) may be used as the dispersion medium. preferable.

Further, when a solvent is used as a dispersion medium, when the ink is heated from the viewpoint of ejection stability, the solvent tends to volatilize and the dispersibility of the pigment tends to decrease. A decrease in pigment dispersibility can be suppressed.

[7.3 Other Additives]
The ink of the present invention may further contain a coupling agent, a solvent, etc., if necessary.

(coupling agent)
The ink of the present invention may further contain various coupling agents as necessary. Adhesion to the printed wiring board can be improved by containing the coupling agent.
Examples of various coupling agents include silane-based, titanium-based, and aluminum-based coupling agents.

(solvent)
The ink of the present invention is preferably solventless from the viewpoint of rapid curing and ejection stability, but may be added to adjust the ink viscosity.

≪Physical properties of the inkjet ink composition of the present invention≫

[1 Viscosity at shear rate]
The viscosity of the ink of the present invention at 25° C. and a shear rate of 1000/sec (hereinafter also referred to as “shear rate viscosity (1000/sec)”) is preferably in the range of 40 to 400 mPa·s, more preferably 50 to 250 mPa. · It is more preferable to be within the range of s. Within the above range, the aforementioned viscosity at 80° C. can be adjusted within the range of 3 to 20 mPa·s, and sufficient ejection stability can be obtained.

In addition, by being within the above range, the shear rate viscosity (1000 / sec) at 25 ° C. is higher than that of conventional inkjet ink compositions in which the temperature at the time of ink ejection is 40 to 60 ° C. Since a compound with a high molecular weight is added, a gel effect occurs relatively early, so polymerization inhibition due to oxygen can be suppressed, and fastness is improved.

In the present invention, the viscosity at shear rate (1000/sec) is a value obtained by the following method.
The ink of the present invention was heated to 25° C., and stress-controlled rheometer Physica MCR301 (diameter of cone plate: 75 mm, cone angle: 1.0°, manufactured by Anton Paar) was used at a shear rate of 1000/sec. Measure.

Further, from the viewpoint of obtaining sufficient ejection stability from an inkjet head, the shear rate viscosity of the ink of the present invention within the range of 70 to 90 ° C. is preferably within the range of 7 to 15 mPa s. It is more preferably in the range of ~13 mPa·s, more preferably in the range of 9 to 12 mPa·s.

[2 Viscosity at shear strain]
In the ink of the present invention, it is preferable to optimize or optimize properties such as viscosity depending on the purpose and conditions of use. Also referred to as “shear strain viscosity”) is preferably within the range of 1 to 1×10 ⁴ Pa·s. Moreover, it is more preferably in the range of 1 to 1×10 ² Pa·s, and even more preferably in the range of 1 to 1×10 Pa·s. Within the above range, the pinning property is improved when the ink is applied onto a recording medium and the temperature is lowered to room temperature, and sufficient fastness of the recorded matter can be obtained. Further, since sufficient pinning properties are obtained, the ink of the present invention can be cured all at once. Batch curing will be described later.
The shear strain viscosity can be adjusted within the above range by including the aforementioned gelling agent in the ink of the present invention.

[3 phase transition point]
The ink of the present invention preferably has a phase transition point within the range of 40 to 100.degree.
When the phase transition point is 40° C. or higher, the ink rapidly gels after landing on the recording medium, thereby improving the pinning property.
In addition, since the phase transition point is 100° C. or less, it is possible to achieve both ink handling property and ejection stability.
The phase transition point of the ink of the present invention is more preferably within the range of 40 to 60°C. When the temperature is within the above range, the ink can be ejected at a relatively low temperature, so the load on the recording apparatus due to the temperature can be reduced.

[4 Method for measuring and determining viscosity and phase transition point in shear strain]
The ink of the present invention was heated to 100° C., and a temperature drop rate of 0.1° C./s was measured using a stress-controlled rheometer Physica MCR301 (cone plate diameter: 75 mm, cone angle: 1.0°, manufactured by Anton Paar). , a strain of 5%, and an angular frequency of 10 radian/s, the ink is cooled to 20° C. to obtain a temperature change curve of viscosity.

The viscosity at 80°C and the viscosity at 25°C can be obtained by reading the viscosity at 80°C and 25°C respectively on the viscosity temperature change curve. The phase transition point is determined as the temperature at which the viscosity becomes 200 mPa·s on the viscosity temperature change curve.

<<Method for producing the inkjet ink composition of the present invention>>
The ink of the present invention can be prepared by mixing the aforementioned polymerizable compound and any other ingredients under heating. Moreover, it is preferable to filter the obtained mixed liquid with a predetermined filter. When preparing an ink containing a pigment, it is preferable to prepare a pigment dispersion containing the pigment and the polymerizable compound, and then mix the pigment dispersion with other components. The pigment dispersion may further contain a dispersant.

The pigment dispersion can be prepared by dispersing a pigment in a polymerizable compound. Pigments can be dispersed using, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like. At this time, a dispersant may be added.

<<Inkjet recording method of the present invention>>
The inkjet recording method of the present invention comprises steps of using the inkjet ink composition of the present invention, ejecting the inkjet ink composition from an inkjet head, and causing the inkjet ink composition to land on a recording medium; The method is characterized by comprising a step of curing the composition with active energy rays or heat.

In the inkjet method, ink is ejected from an inkjet head and landed on a recording medium. The inkjet method is particularly suitable for forming a solder resist pattern and printing characters, since it is easy to apply ink only to a necessary portion.

In the step of curing by irradiation with active energy rays, the ink may be cured immediately after the ink landing step, or may be cured all at once after the ink landing step is completed.
The ink of the present invention has a relatively high viscosity at room temperature (25° C.) and does not spread easily after it lands on a recording medium. After the ink is ejected and landed on the recording medium, it can be cured all at once. By collectively curing, ejection defects due to leaked light can be reduced.

In the present invention, the terms “batch irradiation”, “batch heating” and “batch curing” refer to a plurality of ink droplets ejected in a certain/predetermined range and made to land on a recording medium. Curing is performed by irradiating active energy rays or heating all of the ink droplets that have landed at the same time. That is, instead of curing each droplet of ink that has landed on the recording medium, the ink is grouped in units of a certain/predetermined range (for example, all the ink required to form a predetermined image (pattern) is deposited). It refers to performing ink landing, irradiation with active energy rays, or heating and curing.

Further, it is preferable to form a solder resist film used for a printed circuit board by the inkjet recording method of the present invention.

The inkjet recording method of the present invention will be described below. The inkjet recording method of the present invention comprises (1) the step of ejecting the ink of the present invention from an inkjet head and allowing it to land on a recording medium, and (2) the step of curing the ink that has landed on the recording medium with an active energy ray or heat. , has

[Step (1)]
In step (1), the ink of the present invention is ejected from nozzles of an inkjet head and landed on a recording medium. Although the recording medium is not particularly limited, it is preferably a printed circuit board.

Either an on-demand method or a continuous method may be used as the ejection method from the inkjet head.
On-demand type inkjet heads include electro-mechanical conversion types such as single-cavity type, double-cavity type, bender type, piston type, shear mode type and shared wall type, thermal ink jet type and bubble jet (registered trademark). (Bubble jet is a registered trademark of Canon Inc.) type or the like may be used.

Ejection stability can be obtained by ejecting heated ink droplets from the inkjet head. The temperature of the ink when filled in the inkjet head is preferably in the range of 40 to 100° C., and more preferably in the range of 40 to 90° C. from the viewpoint of further enhancing ejection stability. Further, the viscosity of the ink is preferably in the range of 7 to 15 mPa·s, more preferably in the range of 8 to 13 mPa·s at the discharge temperature.

When using a sol-gel phase transition type ink containing a gelling agent, the temperature of the ink when filled in the inkjet head is in the range of (gelling temperature + 10) to (gelling temperature + 30) ° C. preferably within When the temperature of the ink in the inkjet head is (gelling temperature + 10)°C or higher, the ink does not gel in the inkjet head or on the nozzle surface, and sufficient ejection stability can be obtained. In addition, since the temperature of the ink is (gelling temperature+30)° C. or less, each component contained in the ink is prevented from deteriorating due to the temperature.

The method of heating the ink is not particularly limited. For example, at least one of an ink tank constituting the head carriage, an ink supply system such as a supply pipe and an ink tank in the front chamber immediately before the head, a pipe with a filter, a piezo head, etc. is heated by a panel heater, a ribbon heater, or thermal water. be able to.

From the viewpoint of recording speed and image quality, the amount of ink droplets to be ejected is preferably within the range of 2 to 20 pL.

The printed circuit board, which is a recording medium, is not particularly limited. Copper-clad laminates of all grades (FR-4, etc.) using materials such as copper-clad laminates for high-frequency circuits using PPO, cyanate ester, etc., and other polyimide films, PET films, glass substrates, and ceramic substrates. , a wafer plate, a stainless steel plate, or the like.

[Step (2)]
In the step (2), the ink that has landed on the recording medium is cured by active energy rays or heat. The ink of the present invention can be cured only by irradiation with active energy rays or only by heating, but irradiation with at least active energy rays is preferred, and heating is more preferred.

Examples of active energy rays include electron beams, ultraviolet rays, α rays, γ rays, and X rays, and ultraviolet rays are preferred.
Irradiation of ultraviolet rays can be performed under the condition of a wavelength of 395 nm using, for example, a water-cooled LED manufactured by Phoseon Technology. By using an LED as a light source, it is possible to suppress poor curing of the ink due to melting of the ink by the radiant heat of the light source.

The peak illuminance of ultraviolet rays having a wavelength in the range of 370 to 410 nm on the surface of the solder resist film is preferably in the range of 0.5 to 10 W/cm ² and is in the range of 1 to 5 W/cm ² is more preferable, and irradiation with ultraviolet rays is performed so as to be within the above range. From the viewpoint of suppressing the ink from being irradiated with radiant heat, the amount of light irradiated to the solder resist film is preferably less than 1000 mJ/cm ² .

Irradiation with the active energy ray is preferably performed within 0.001 to 300 seconds after the ink has landed, and in order to form a high-definition solder resist film, it is performed within 0.001 to 60 seconds. more preferred.

From the viewpoint of suppressing polymerization inhibition due to oxygen, it is preferable to cure the ink by irradiating the deposited ink with active energy rays in an atmosphere with an oxygen concentration in the range of 0.1 to 10.0% by volume. In addition, from the viewpoint of making it difficult for blooming to occur, the oxygen concentration is more preferably in the range of 0.5 to 8.0% by volume, and more preferably in the range of 0.5 to 6.0% by volume. .

As for the heating method, for example, it is preferable to put it in an oven set within the range of 110 to 180°C for 10 to 90 minutes.

<<Inkjet recording system of the present invention>>
The inkjet recording system of the present invention includes an inkjet head that uses the inkjet ink composition of the present invention and ejects the inkjet ink composition, and an active energy ray irradiation that irradiates the inkjet ink composition that has landed on a recording medium with an active energy ray. and a heating unit for heating the inkjet ink composition irradiated with the active energy ray.

That is, in the system of the present invention, an inkjet head that ejects an inkjet ink composition, an active energy ray irradiation unit that irradiates an active energy ray to the inkjet ink composition that has landed on a recording medium, and an active energy ray irradiation unit that irradiates the active energy ray A recording apparatus having a heating section for heating the inkjet ink composition and the ink of the present invention are used.

It should be noted that the recording method of the inkjet recording apparatus is preferably a scanning method from the viewpoint of ejection stability and printing accuracy.

The inkjet recording apparatus used in the present invention includes an inkjet head that ejects the ink of the present invention onto a recording medium, and an active energy ray (for example, ultraviolet rays) that irradiates the ink of the present invention that has landed on the recording medium to produce the ink of the present invention. and an active energy ray irradiating part that cures and a heating part that heats and further advances curing.

Types of inkjet recording devices (printers) include single-pass printers and serial printers. A single-pass printer is equipped with a line head having a length (recording medium width) corresponding to the width of the recording medium, and the head is (almost) fixed without moving for one pass (single pass). Printing is done in

On the other hand, in a serial printer, printing is normally performed in two or more passes (multipass) while the head reciprocates (shuttles) in a direction perpendicular to the transport direction of the recording medium.

Single-pass printers require a line head by arranging multiple inkjet heads, which requires a relatively large number of inkjet heads. Serial printers, on the other hand, consist of only a small number of recording heads. can be done.

In the present invention, either type of printer can be used, preferably a serial printer.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these. In the examples, "parts" or "%" are used, but "mass parts" or "mass%" are indicated unless otherwise specified.
Also, in the following examples, the operations were carried out at room temperature (25° C.) unless otherwise specified.

[Example 1]
<Preparation of Yellow Pigment Dispersion Liquid Y>
Put the following dispersant 1 and dispersant 2, and the dispersion medium in a stainless steel beaker, heat and dissolve with stirring for 1 hour while heating on a hot plate at 65 ° C., cool to room temperature, add the following pigment, It was placed in a glass bottle together with 200 g of 0.5 mm zirconia beads and sealed.
The zirconia beads were removed after dispersion treatment was carried out with a paint shaker until a desired particle size was obtained.

Dispersant 1: PX4701 (manufactured by BASF) 6.0 parts by mass Dispersant 2: Solsperse 22000 (manufactured by Lubrizol Japan)
0.3 parts by mass dispersion medium: dipropylene glycol diacrylate (containing 0.2% UV-10)
61.5 parts by mass Pigment: PY185 (manufactured by BASF, Paliotol Yellow D1155)
10.2 parts by mass

<Preparation of Cyan Pigment Dispersion Liquid C>
The yellow pigment dispersion was prepared in the same manner as dispersion Y, except that the dispersant, dispersion medium and pigment were changed as shown below.

Dispersant: PX4701 (manufactured by BASF) 7.0 parts by mass Dispersion medium: dipropylene glycol diacrylate (containing 0.2% UV-10)
70 parts by mass Pigment: PB15:4 (manufactured by Dainichiseika, Chromofine (registered trademark) Blue 6332JC)
23 parts by mass

In this experiment, the following compounds were used as polyfunctional compound A, acrylate oligomer, monomer, polymerization initiator, polymerization inhibitor, and gelling agent.

<Polyfunctional compound A>
Maleimide A: BMI-5100, Daiwa Kasei Kogyo Co., Ltd. Maleimide B: BMI-1000, Daiwa Kasei Kogyo Co., Ltd. Maleimide C: N-phenylmaleimide, Tokyo Chemical Industry Co., Ltd. Methacrylate A: DCP, Shin-Nakamura Chemical Co., Ltd. methacrylate B: HD-N, Shin-Nakamura Chemical Co., Ltd. methacrylate C: 4G, Shin-Nakamura Chemical Co., Ltd. methacrylate D: M301, Miwon Co., Ltd. methacrylate E: M-40G, Shin-Nakamura Chemical Co., Ltd. methacrylate F: EM310, Changxing Methacrylate G: M1131 manufactured by Kagaku Kogyo Co., Ltd., manufactured by Miwon

<Acrylate Oligomer>
Urethane acrylate oligomer A:
CN8885, Sartomer urethane acrylate oligomer B:
CN989, Sartomer Urethane Acrylate Oligomer C:
CN972, Sartomer urethane acrylate oligomer D:
CN975NS, Sartomer urethane acrylate oligomer E:
CN992, Sartomer acrylate oligomer A (hyperbranched structure):
CN2304, manufactured by Sartomer Acrylate Oligomer B (hyperbranched structure):
SP1106, Miwon acrylate oligomer C (hyperbranched structure):
6361-100, manufactured by Eternal Chemical Co., Ltd. Polyester acrylate oligomer:
CN2259, manufactured by Sartomer

<Monomer>
[Monofunctional compound]
Acrylate a: M150, manufactured by Miwon Acrylate b: 4-HBA, manufactured by Osaka Organic Chemical Industry Co., Ltd. [Multifunctional compound B]
Acrylate c: M222, manufactured by Miwon Acrylate d: SR259, manufactured by Sartomer Acrylate e: A-DCP, manufactured by Shin-Nakamura Chemical Co., Ltd. Acrylate f: SR492, manufactured by Sartomer

<Polymerization initiator>
Type I type (Norrish type I) A:
Omnirad® 907, IGM Resins B.I. V. Company Type I type (Norish type I) B:
Omnirad® 819, IGM Resins B.I. V. Company Type II type (Norish type II):
Speedcure® ITX, manufactured by Lambson

<Polymerization inhibitor>
Irgastab (registered trademark) UV-10, manufactured by BASF

<Gelling agent>
Gelling agent A: Kaowax T1, manufactured by Kao Corporation Gelling agent B: Excepal SS, manufactured by Kao Corporation Gelling agent C: Amleps PC, manufactured by KOKYU ALCOHOL KOGYO CO., LTD.

<Ink preparation>
Ink 1 was prepared by mixing the following components and filtering through a Teflon (registered trademark) 3 μm membrane filter manufactured by ADVATEC.

<Polyfunctional compound A>
Maleimide A 3.0 parts by mass <Acrylic oligomer>
Urethane acrylate oligomer A 15.0 parts by mass <monomer>
Acrylate b 10.0 parts by mass Acrylate c 36.7 parts by mass Acrylate d 20.0 parts by mass Acrylate f 10.0 parts by mass <Polymerization initiator>
Type I type A 1.0 parts by mass Type I type B 1.0 parts by mass Type II type 2.0 parts by mass <Polymerization inhibitor>
Irgastab (registered trademark) UV-10 0.1 parts by mass <Pigment dispersion>
Dispersion Y 0.7 parts by mass Dispersion C 0.5 parts by mass

Inks 2 to 38 were prepared in the same manner, except that the polyfunctional compound A, acrylate oligomer, monomer, and gelling agent were changed to the types and added amounts shown in Tables I to VII.

<Formation of Cured Ink Film by Inkjet Method (Sample A)>
Each of the prepared inks was loaded into an inkjet recording apparatus having an inkjet recording head equipped with piezo inkjet nozzles. Using this apparatus, a cured ink film was formed on a polyimide film having a thickness of 100 μm.

The ink supply system consists of an ink tank, an ink flow path, a sub-ink tank just before the inkjet recording head, a pipe with a metal filter, and a piezo head. The ink is heated to 80° C. from the ink tank to the head portion. A heater was also incorporated in the piezo head to heat the ink in the recording head to 80.degree. The piezo head has a nozzle diameter of 22 μm and a nozzle resolution of 360 dpi, and is staggered to form a nozzle array of 720 dpi.

Using this inkjet device, a voltage is applied so that the droplet volume becomes a dot of 6.0 pL, and a solid pattern of 20 mm × 50 mm is printed on the substrate so that the thickness is 20 μm. An LED lamp (395 nm, 8 W/cm ² , water cooled unit) manufactured by Phoseon Technology was irradiated at 1 W/cm ² and 500 mJ/cm ² to cure the coating film. After that, it was placed in an oven set at 150° C. for 60 minutes for curing, and a sample A was obtained.

<Solder Resist Pattern Formation by Inkjet Method (Sample B)>
Similarly, a solder resist pattern was formed on a copper clad laminate for printed wiring board (FR-4, thickness 1.6 mm, size 150 mm×95 mm) to obtain sample B.

[evaluation]

<Flexibility>
The prepared sample A was subjected to a flex resistance test according to the method described in "JIS K-5600-5-1".
Specifically, using a cylindrical mandrel bending tester, mandrels with diameters of 2, 3, 4, 5, 6, 7 and 8 mm were used to measure the mandrel diameter at which cracks in the cured ink film were visually confirmed. bottom.
Evaluation was performed according to the following criteria. A value of Δ or more was regarded as a practically acceptable range.
(standard)
A: No cracks were observed on any mandrel.
Good: Cracks were observed on mandrels with a diameter of 4 mm or less, but were not observed on mandrels with a diameter of 5 mm or more.
Δ: Cracks were observed on mandrels with a diameter of 7 mm or less, but were not observed on mandrels with a diameter of 8 mm.
x: A crack was confirmed by the mandrel with a diameter of 8 mm.

<Ruggedness (pencil hardness)>
For the prepared sample B, according to the description method of "JIS Standard K-5400", using Hi-Uni (registered trademark) manufactured by Mitsubishi Pencil, as an evaluation of robustness, that is, "scratch resistance", the pencil hardness of the surface. was measured.

Specifically, the wood part of the pencil was scraped off, and the lead was made 5-6 mm long. A pencil having a circular cross section was used by smoothing the tip of the lead with abrasive paper. The pencil was held at an angle of 45 degrees to the sample surface and the coating was scratched at an angle of 45 degrees with a weight of 1 kg applied to the sample surface. The maximum hardness of the pencil where the coating did not reach the substrate was rated.

Evaluation was performed according to the following criteria. A value of Δ or more was regarded as a practically acceptable range.
(standard)
A: Pencil hardness of 6H or more.
Good: Pencil hardness 5H.
Δ: Pencil hardness of 3H or 4H.
x: Pencil hardness less than 3H.

<Robustness in long-term storage (pencil hardness)>
The prepared sample B was allowed to stand under the conditions of 85° C. and 85% relative humidity for one month, and then the pencil hardness was measured in the same manner as above.
Evaluation was performed according to the following criteria. A value of Δ or more was regarded as a practically acceptable range.
(standard)
A: Pencil hardness of 6H or more.
Good: Pencil hardness 5H.
Δ: Pencil hardness of 3H or 4H.
x: Pencil hardness less than 3H.

Tables I to VII below show the amounts of the components added and the evaluation results for each ink. "-" indicates not applicable or not measured. Especially about the addition amount, it shows that it was not added. Moreover, "monofunctional" indicates a monofunctional compound.

From the above results, the ink of the present invention can achieve both flexibility and fastness in the resulting recorded matter, and even during long-term storage, sufficient fastness can be obtained in the recorded matter, and deterioration of fastness is suppressed. found that it can be done. In addition, it was found that the flexibility, fastness, and fastness to long-term storage of recorded matter are further improved by appropriately selecting polyfunctional compound A, acrylate oligomer, monomer, and gelling agent.

[Example 2]
<Ink preparation>
Inks 39 to 45 were prepared in the same manner, except that the polyfunctional compound A, acrylate oligomer, monomer and gelling agent were changed to the types and added amounts shown in Table VII.

(Measurement of shear rate viscosity)
Then, using a stress-controlled rheometer Physica MCR301 (cone plate diameter: 75 mm, cone angle: 1.0°, manufactured by Anton Paar), the viscosity was measured at a shear rate of 1000/sec.

(Measurement of shear strain viscosity)
In addition, the ink of the present invention was heated to 100° C., and the temperature was lowered to 0.1° C. using a stress-controlled rheometer Physica MCR301 (cone plate diameter: 75 mm, cone angle: 1.0°, manufactured by Anton Paar). /s, a strain of 5%, and an angular frequency of 10 radian/s. Then, the viscosity at 25° C. was determined by reading from the viscosity temperature change curve.

Then, the same evaluation as in Example 1 was performed. The amounts of the components added and the evaluation results for each ink are shown in Table VIII below. "-" indicates not applicable or not measured. Especially about the addition amount, it shows that it was not added. Moreover, "monofunctional" indicates a monofunctional compound.

From the above results, the ink of the present invention has a shear viscosity at 25° C. and a shear rate of 1000/sec in the range of 40 to 400 mPa s, whereby the ejection stability of the ink can be obtained, and the flexibility of the printed matter can be improved. and fastness are further improved, and it was found that by setting the viscosity within the range of 50 to 250 mPa·s, both flexibility and fastness can be achieved in the recorded matter.

In addition, by setting the viscosity to 1 Pa s or more at 25° C., a shear strain of 5%, and an angular frequency of 10 radian/s, the pinning property is improved when the ink is applied to the recording medium and cooled to room temperature. It was found that sufficient fastness was obtained in recorded matter.

By recording using the inkjet ink composition of the present invention, it is possible to achieve both flexibility and robustness in the resulting recorded matter, and to suppress deterioration in robustness during long-term storage. It can be suitably used for solder resist ink that protects patterns.

Claims (12)

An inkjet ink composition that is cured by active energy rays or heat,
Containing a polyfunctional compound A and an acrylate oligomer,
The degree of resonance stabilization when the polyfunctional compound A becomes a radical is equal to or less than that of styrene,
The inkjet ink composition, wherein the acrylate oligomer has 3 or more functional groups. 2. The inkjet ink composition of claim 1, wherein the Alfrey-Price Q value of the polyfunctional compound A is in the range of 0.70 to 1.00. 3. The inkjet ink composition according to claim 1, wherein the inkjet ink composition has a shear viscosity of 40 to 400 mPa·s at 25° C. and a shear rate of 1000/sec. 4. The inkjet ink composition according to any one of items 1 to 3, wherein the content of the polyfunctional compound A in the inkjet ink composition is in the range of 1 to 15% by mass. thing. The inkjet ink composition according to any one of claims 1 to 4, wherein the content of the acrylate oligomer in the inkjet ink composition is in the range of 10 to 40 mass%. The inkjet ink composition according to any one of claims 1 to 5, wherein the acrylate oligomer is a urethane acrylate oligomer. 7. The inkjet ink composition of any one of claims 1-6, wherein the acrylate oligomer is a hyperbranched acrylate oligomer. Any one of claims 1 to 7, further comprising a monomer, wherein the content of the polyfunctional compound B with respect to the total mass of the monomer is in the range of 90 to 100% by mass. The described inkjet ink composition. The inkjet ink composition according to any one of claims 1 to 8, wherein the polyfunctional compound A is a methacrylate compound. 10. The inkjet ink composition of any one of claims 1-9, further comprising a gelling agent. An inkjet recording method using an inkjet ink composition,
Using the inkjet ink composition according to any one of claims 1 to 10, and
A step of ejecting the inkjet ink composition from an inkjet head and landing it on a recording medium;
An inkjet recording method, comprising a step of curing the inkjet ink composition that has landed on the recording medium with an active energy ray or heat. An inkjet recording system using an inkjet ink composition,
Using the inkjet ink composition according to any one of claims 1 to 10, and
an inkjet head for ejecting the inkjet ink composition;
an active energy ray irradiation unit that irradiates the inkjet ink composition that has landed on a recording medium with an active energy ray, and
An inkjet recording system comprising a heating section for heating the inkjet ink composition irradiated with the active energy ray.