JP3480813B2 - Ink for inkjet printer - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink-jet ink, and more particularly to an ink-jet ink capable of obtaining a thick film printed matter.

[0002]

2. Description of the Related Art Printed matter formed from thick film ink is used in various fields. For example, it is used for printing Braille prints for visually impaired persons, printing product numbers on electronic components such as printed wiring boards, and the like.

For the production of these printed materials, screen printing, gravure printing, and the like, which make it possible to obtain thick film printed materials relatively easily, are widely used, and solvent-based inks and UV-curable inks are used. There is.

However, in screen printing, gravure printing, etc., it is necessary to make a plate in advance, and it is not efficient when printing a large number of small quantities.

Therefore, as a method for obtaining a printed matter without performing plate making, electronically produced image forming data is
There has been proposed a method of outputting to a printer to form an image. To form a thick film image, the applicant has developed and sold an ink containing a heat-sensitive foaming agent. With this ink, a thick film-like printed material can be obtained by foaming the ink by heating. However, the thick film-like printed matter formed by foaming has a problem in that it cannot be obtained sufficiently in an application requiring durability because the inside is not dense.

On the other hand, in order to perform thick film printing, it has been proposed to produce a printed matter by using an ultraviolet curable ink. The UV curable ink uses a photopolymerizable monomer that participates in the polymerization reaction in the UV curing reaction for the purpose of diluting the UV curable composition with the photopolymerizable prepolymer, and the shape retention of the printed ink is It has the characteristic of being good.

[0007]

The ink jet printer is a printing method which can easily print on various substrates to be printed and is widely used. Inkjet printers have a continuous method of charging and deflecting liquid droplets, a piezoelectric method of applying a voltage to a piezoelectric crystal to pressurize it by crystal distortion, and a heating method of forming bubbles by heating ink and ejecting it by the pressure. Although ink-jet type ink jet printers that have a simple structure and are easy to handle, such as piezoelectric or heat-type ink jet printers that mechanically pressurize ink and eject it from a nozzle, It is necessary to reduce the size of the nozzle so that the ink can be easily ejected from the nozzle.

For example, an ink for an ink jet printer made of an ultraviolet curable ink is disclosed in JP-A-7-22424.
As described in Japanese Patent Publication No. 1, however, an aqueous medium is used as a dispersion medium of the ink and contains 50% or more of water based on the total weight of the ink to facilitate jetting. However, in such an ultraviolet curable ink, Thick film printing was not possible.

As described above, the conventional ultraviolet curable ink for ink jet printers can be handled easily if the viscosity of the ink is reduced so that the ink is easily ejected from the nozzle, but a printed matter of sufficient thickness cannot be obtained. There was a problem, and it could not be used for applications such as Braille.

An object of the present invention is to provide an ink for an ink jet printer capable of thick film printing, which is made of an ultraviolet curable ink.

[0011]

The present invention provides a photopolymerizable prepolymer in an ink for an ink jet printer,
An ink comprising a photopolymerizable monomer and a photopolymerization initiator and having a surface tension of 33 mN / m or more. The above ink is one in which no dispersion medium or solvent other than the photopolymerizable monomer is added as a diluent. The photopolymerizable prepolymer is the above-mentioned ink containing an epoxy (meth) acrylate. Photopolymerizable monomer is N
-The above ink containing acryloylmorpholine. The above-mentioned ink which is an ink for braille printing or an ink for thick film printing on synthetic resin, metal, glass or ceramics.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention has found that, by using an ultraviolet curable ink having a large surface tension as an ink for an ink jet printer, thick film printing can be performed regardless of the viscosity of the ink. The present invention has been conceived. The ultraviolet-curable inkjet printer ink of the present invention is a composition containing a photopolymerizable prepolymer, a photopolymerizable monomer, and a photopolymerization initiator, and is prepared by changing the content ratio of each composition. It is possible to obtain an ink having a surface tension of. The ultraviolet curable ink for inkjet printers of the present invention has a surface tension of 33 mN / m or more,
More preferably, it is N / m or more.

In the present invention, photopolymerizability means the property of being polymerized by ultraviolet rays, electron beams, other radiations, etc., and light means ultraviolet rays, electron beams, other radiations capable of causing such a reaction. Also means.

As the photopolymerizable prepolymer that can be used in the present invention, the photopolymerizable prepolymer used in the production of an ultraviolet curable resin can be used. Specifically, polyester (meth) acrylate, bisphenol-based epoxy (meth) acrylate, bisphenol A-based epoxy (meth) acrylate, propylene oxide-modified bisphenol A-based epoxy (meth) acrylate, alkali-soluble epoxy (meth) acrylate, acrylic Modified epoxy (meth) acrylate, phosphoric acid modified epoxy (meth) acrylate, polycarbonate urethane (meth) acrylate, polyester urethane (meth) acrylate, alicyclic urethane (meth) acrylate, aliphatic urethane (meth) acrylate, polybutadiene (Meth) acrylate, polystyryl (meth)
An acrylate etc. can be mentioned.

Specifically, the diamond beam UK6105,
Diamond beam UK6038 (all made by Mitsubishi Rayon
Epoxy acrylate), DiaBeam UK605
5, Diamond Beam UK6063 (all are urethane acrylates made by Mitsubishi Rayon), Diamond Beam UK42
03 (Made by Mitsubishi Rayon, ester acrylate molecular weight 1282), Kayarad R300, Kayarad R13
0, Kayarad R190, Kayarad R280 (all are epoxy acrylates manufactured by Nippon Kayaku), Kayarad UX2201, Kayarad UX3204, Kayarad U
X6101, Kayarad UX8101 (Nippon Kayaku urethane acrylate), Orestar RA15
74 (mixture of epoxy-based, ester-based, and urethane-based acrylates manufactured by Mitsui Chemicals).

In the present invention, one or more of these photopolymerizable prepolymers can be used. In particular, among these, the photopolymerizable prepolymer of epoxy acrylate has a large effect of increasing the surface tension.

In the present invention, (meth) acrylate means acrylate and methacrylate, and may include both.

The photopolymerizable monomer used in the ink of the present invention includes alkyl (meth) acrylate, alicyclic (meth) acrylate, alkylene glycol type (meth) acrylate, ester type (meth) acrylate and trimethylol. Propane type (meth) acrylate,
Pentaerythritol type (meth) acrylate, isocyanurate type (meth) acrylate, phenyl type (meth) acrylate, benzyl type (meth) acrylate,
Phenoxy type (meth) acrylate, bisphenol A
Type (meth) acrylate, alcohol type (meth) acrylate, epoxy type (meth) acrylate, allyl type (meth) acrylate, glycidyl type (meth) acrylate, carboxyl type (meth) acrylate, vinyl type (meth) acrylate, ether type (Meth) acrylate etc. can be mentioned.

Specifically, butanediol mono (meth)
Acrylate, 2-hydroxyethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, polyethylene glycol di (meth) acrylate, N, N-dimethylacrylamide, N-methylolacrylamide , N-vinylformamide, N-acryloylmorpholine, neopentyl glycol di (meth)
Acrylate, 1,6-hexanediol di (meth) acrylate, triethylene glycol di (meth) acrylate, cyclohexyl (meth) acrylate, tetraethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, N-vinyl Pyrrolidone, cyclohexyl (meth) acrylate, tetraethylene glycol methacrylate, isobonyl (meth) acrylate, dicyclopentenyl (meth) acrylate and the like can be mentioned. Among these, N-acryloylmorpholine can be particularly mentioned. One or more of these photopolymerizable monomers can be used.

As the polymerization initiator, acetophenone, 2,2-diethoxyacetophenone, p-dimethylaminoacetophen, p-dimethylaminopropiophenone, benzophenone, 2-chlorobenzophenone, p
p'-dichlorobenzophene, pp'-bisdiethylaminobenzophenone, Michler's ketone, benzyl, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-propyl ether, benzoin isobutyl ether, benzoin-n-butyl ether, benzyl Dimethyl ketal, tetramethyl thiuram monosulfide,
Thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, azobisisobutyronitrile, benzoin peroxide, di-ter-butyl peroxide, 1-hydroxycyclohexyl phenyl ketone, 2
-Hydroxy-2-methyl-1-phenyl-1-one,
1- (4-isopropylphenyl) -2-hydroxy-
2-Methylpropan-1-one and methylbenzoyl formate can be mentioned.

In the case of the cationic polymerization type, a photoinitiator such as an aromatic diazonium salt, an aromatic halonium salt, an aromatic sulfonium salt or a metallocene compound is used.
Specific examples thereof include triphenylsulfonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate and the like. The photopolymerization initiator is
One type or a plurality of types may be used, and the photopolymerization initiator may be used in combination with the sensitizer. Examples of the sensitizer include an aliphatic amine, an amine containing an aromatic group, an amine sensitizer such as piperidine, an aryl sensitizer, a urea sensitizer such as o-tolylthiourea, sodium diethyldithiophosphate, and an aromatic sulfinic acid. Sulfur compound-based sensitizers such as soluble salts of
Nitrile sensitizers such as N, N-di-substituted-p-aminobenzonitrile, phosphorus n-sensitizers such as tri-n-butylphosphine and sodium diethyldithiophosphide, Michler's ketone, N-nitrisohydroxylamine derivatives, oxazolidine Examples thereof include compounds, tetrahydro-1,3-oxazine compounds, nitrogen compound sensitizers such as formaldehyde or a condensate of acetaldehyde and diamine.

The photopolymerizable prepolymer and the photopolymerizable monomer are preferably used in an amount of up to 2000 parts by weight, preferably 100 parts by weight to 800 parts by weight, based on 100 parts by weight of the photopolymerizable prepolymer. Is preferred. The photopolymerization initiator and the sensitizer are preferably used in an amount of 0.1 to 20% by weight based on the total amount of the ultraviolet curable resin.

When the ultraviolet curable ink of the present invention is colored, colorants such as dyes and pigments are mixed. As the dye that can be used, various dyes that have been conventionally used in ink jet inks or ultraviolet curable inks can be used, such as azo dyes, direct dyes such as phthalocyanine dyes, and acid dyes such as anthraquinone dyes. Is mentioned.

As the pigment, it is possible to use various organic and inorganic pigments conventionally used in ink jet inks or ultraviolet curable inks. For example, azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments and chelate azo pigments, phthalocyanine pigments, perylene pigments, antothequinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, polycyclic pigments such as quinophthalone pigments. , Basic dye type lakes and acid dye type lakes, organic pigments such as nitro pigments, nitroso pigments, aniline black and daylight fluorescent pigments, inorganic pigments such as titanium oxide, iron oxides and carbon blacks Is mentioned.
These dyes and pigments may be used in combination.

The ultraviolet-curable ink-jet ink of the present invention contains an acrylic resin, a silicone resin, an acetylene glycol compound, amines, salts, etc. for the purpose of adjusting physical properties such as viscosity and stabilizing the dispersion of pigments. Acids and the like may be used as additives. Also, for the purpose of adjusting the viscosity,
You may use a solvent. Examples of the solvent that can be used include solvents such as ketones, esters, ethers and alcohols.

However, in order to obtain a thick-film printed matter, it is preferable to use only a photopolymerizable monomer as a diluent and use an ink containing no solvent or the like and substantially not using a solvent.

The UV-curable ink jet printer ink of the present invention is prepared by mixing a photopolymerizable prepolymer, a photopolymerizable monomer, a photopolymerization initiator, a coloring material and the like at a predetermined ratio and kneading. be able to. The kneading can be performed using a disperser.

Examples of the disperser include a ball mill, a roll mill and a sand mill. Among them, a high speed type sand mill is preferable, and for example, a super mill, a sand grinder, a bead mill, an agitator mill, a grain mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names).
Etc.

The ink for an ink jet printer of the present invention is a continuous type in which droplets are charged and deflected, a piezoelectric type in which a voltage is applied to a piezoelectric crystal to pressurize it due to crystal distortion, and a bubble is formed by heating the ink. The ink jet printer can be used in any method such as a heating type which ejects by the pressure, but an ink jet printer in which heat is not applied to the ink is preferable from the viewpoint of ink stability.

A color image can be formed by using the ink containing a coloring material as the ink of the present invention.

When one dot size and a predetermined size are required as in Braille, it is necessary to eject an amount of ink corresponding to the dot to be formed from the nozzle of the ink jet printer. is there. In the case of a nozzle having a small discharge amount, ink is discharged a plurality of times at the same location to form dots of a predetermined size.

The ink for an ink jet printer of the present invention is printed on a synthetic resin substrate such as acrylic resin, polycarbonate, polyethylene terephthalate, acryl butadiene styrene copolymer, epoxy resin or phenol resin, or a substrate such as glass. However, in order to obtain a printed matter having a large film thickness, it is preferable to use a substrate to be printed having a small wetting index.

Further, since the printed matter formed by the ink of the present invention is formed by the ultraviolet curable resin, it has high solvent resistance and chemical resistance. It is suitable for printing on various electronic materials that are subjected to cleaning treatment.

The substrate on which the ink of the present invention is adhered is cured by ultraviolet rays, electron beams, etc., but when printing is performed using a plurality of colors of ink, the inks of a plurality of colors are adhered. After irradiating the printing substrate with ultraviolet rays, etc.,
Alternatively, the step of irradiating ultraviolet rays for each color may be repeated for each color.

In the irradiation of ultraviolet rays or the like, the substrate to be printed may be thermally deformed by the heat generated by the ultraviolet lamp. Therefore, an irradiation device is used so that only the ultraviolet rays are irradiated and the heat rays are not irradiated. It is necessary.

[0037]

EXAMPLES The present invention will be described below with reference to examples. Example 1 An ink jet ink was prepared by mixing a photopolymerizable prepolymer, a photopolymerizable monomer, and a photopolymerization initiator whose types and amounts used in Table 1 are expressed in parts by weight and then kneading them for 5 minutes using a ball mill. . The viscosity of the obtained ink is 25 ° C ± 2 ° C.
Under the conditions described above, a viscometer (VDA-K type manufactured by Shibaura System) was used to measure at 6 revolutions / minute, and the results are shown in Table 1.
Similarly, the surface tension is measured by a surface tensiometer (CBVP-Z type manufactured by Kyowa Interface Science Co., Ltd.) under the condition of 25 ° C. ± 2 ° C.,
The measurement results are shown in Table 1.

Next, the obtained ink was applied to a synthetic resin plate A (acrylic butadiene styrene copolymer Psycolac EX-21L manufactured by Ube Saikon Co., Ltd.) and a synthetic resin plate B (polycarbonate Mitsubishi Engineering Plastics Iupilon NF2000). Inkjet printer (Quantum8 made by FOXJET)
So that the amount of ink for one dot is 2 μl
After printing by ejecting ink several times to the dots, the printed matter is irradiated with ultraviolet rays at an intensity of 300 mW /
In cm ^2, integrated light quantity irradiated so that the 1500 mJ / cm ^2, to cure the ink. The ink film thickness of the obtained printed matter was measured with a film thickness meter (digital film thickness meter MG-4 manufactured by Tokyo Process Service Co., Ltd.), and the measurement results are shown in Table 1.
Shown in. The obtained dot-shaped printed matter had a size and height suitable for Braille.

Examples 2 to 6 Comparative Examples 1 to 4 Example 1 except that the photopolymerizable prepolymer and the photopolymerizable monomer of Example 1 were replaced with those shown in Table 1.
Inks of Examples 2 to 18 and Comparative Examples 1 to 4 were prepared in the same manner as in Example 1, and surface tension and viscosity were measured in the same manner as in Example 1 and printing was then performed to obtain a film of the obtained ink. The thickness was measured and the results are shown in Table 1.

[0040]

[Table 1] Photopolymerizable Photopolymerizable Photopolymerizable surface Viscosity Printed film thickness (μm) Polymer monomer Initiator Tension Synthetic resin plate type: weight part Type: weight part weight part mN / m cPs A B Example 1 A: 29.6 a: 66.6 3.8 47 96.6 494 213 Example 2 A: 17.4 a: 66.9 b: 17.4 4.3 42.5 28.8 432 202 Example 3 B: 34.8 a: 60.4 4.3 37.3 96.8 424 233 Example 4 B: 17.4 a: 66.9 b : 17.4 4.3 39 69.3 367 200 Example 5 C: 17.4 a: 78.3 4.3 42.9 55.3 433 200 Example 6 C: 17.4 a: 60.9 b: 17.4 4.3 42.7 50.5 416 198 ───────────── ────────────────────── Comparative Example 1 A: 17.4 a: 60.9 c: 17.4 4.3 32.6 11.9 252 139 Comparative Example 2 D: 17.4 a: 60.9 c: 17.4 4.3 32.9 19.2 252 120 Comparative Example 3 B: 17.4 a: 60.9 c: 17.4 4.3 32.3 22.4 255 138 Comparative Example 4 E: 17.4 a: 51.9 b: 29.6 3.7 31.6 48.5 213 105

However, in Table 1, the photopolymerizable prepolymers A to E, the photopolymerizable monomers a to c, and the photopolymerization initiator are as follows. Photopolymerizable prepolymers A to NA: Diamond Beam UK6105 (Mitsubishi Rayon's epoxy acrylate molecular weight 763) B: Diamond Beam UK6038 (Mitsubishi Rayon urethane urethane acrylate molecular weight 3600 to 3700) C: Diamond Beam UK6074 (Mitsubishi Rayon urethane Acrylate acrylate molecular weight 300 to 900) D: Olester RA1574 (Mitsui Chemicals epoxy, ester, urethane acrylate mixture) E: DIABEAM UK6074 (Mitsubishi Rayon urethane acrylate molecular weight 300 to 900) Photopolymerizable monomer a to c a: acryloylmorpholine b: 1,6-hexanediol acrylate c: 2-ethylhexyl acrylate photoinitiator Irgacure 1700 (Ciba Spec (Made by Charity Chemicals)

[0042]

INDUSTRIAL APPLICABILITY The ink for an ink jet printer of the present invention can easily form a thick film printed matter, and the obtained printed matter has good water resistance, chemical resistance, abrasion resistance, light resistance and the like. It is suitable for printing printed materials in Braille for the visually impaired, guide plates, and various electronic components.

Claims (5)

(57) [Claims] 1. An ink for an inkjet printer, which comprises a photopolymerizable prepolymer, a photopolymerizable monomer, and a photopolymerization initiator, and has a surface tension of 37.3 mN / m or more . 2. The ink according to claim 1, wherein a dispersion medium other than the photopolymerizable monomer or a solvent is not added as a diluent. 3. The photopolymerizable prepolymer contains an epoxy (meth) acrylate.
Or the ink according to any one of 2 above. 4. The photopolymerizable monomer contains N-acryloylmorpholine.
Ink according to any one of. 5. A braille printing ink or synthetic resin,
The ink according to any one of claims 1 to 4, which is an ink for thick film printing on metal, glass or ceramics.