JPH02206661A - Ink composition - Google Patents

Abstract

PURPOSE:To obtain a composition providing excellent printing having high fixing strength, frictional resistance and excellent dot reproducibility regardless of paper quality in a composition for ink jet recording device comprising a vehicle and a coloring material, by adding a specific amount of an antioxidant to the composition. CONSTITUTION:An ink composition which comprises a vehicle [preferably mixture of (semi)solid such as carnauba wax having melting point or pour point higher than normal temperature and fluid such as liquid paraffin] and a coloring material (preferably oil-soluble dye having heat resistance and water resistance) and delivered from an ink jet recording device at normal temperature-high temperature is blended with 0.1-50wt.%, preferably 3.0-40wt.% antioxidant (preferably phenol-based antioxidant having 50-150 deg.C melting point) to give a composition having excellent thermal stability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ink composition used in an inkjet recording device. More specifically, the present invention relates to an ink composition that is used for inkjet recording at temperatures higher than room temperature. [Prior Art] Inkjet recording is excellent in quietness during recording and high-speed printing performance. BACKGROUND ART Liquid ink compositions based on water or the like have conventionally been used as ink compositions for inkjet recording. However, since ink is recorded by soaking into the paper, it has the disadvantage that when recording on paper where ink easily soaks, bleeding occurs, the periphery of the recorded dots becomes unclear, and the print quality deteriorates. For this reason, the heat related to paper quality (as an ink composition that provides good print quality, U.S. Patent No. 4390369.44849
Publication No. 48.4659383, JP-A-55-54368
．． Japanese Unexamined Patent Publication No. 58-108271 proposes a method of using a hot-melt ink composition that is solid at room temperature, heating and melting the solid ink at a high temperature, causing it to fly, and cooling and solidifying it on recording paper to form recording dots. has been done. [Problems to be Solved by the Invention] In ink compositions based on water or the like, the printing quality varies depending on the paper quality of the recording paper, ranging from good printing quality to extremely poor printing quality. In fact, an ink composition that satisfies both has not been realized because the dependence is large and the ink takes a long time to dry after printing. In addition, although conventional hot melt ink compositions have good compatibility with recording paper and drying properties after printing, ink droplets rapidly cool and solidify on the surface of the recording paper during recording. The ink dots are raised and have low fixation strength with the recording paper, causing them to peel off due to external friction, heat, pressure, etc., and cause the ink image to become smeared. Furthermore, rapid heating and cooling cycles tend to oxidize the ink material and increase the viscosity of the ink, resulting in the problem of unstable ink ejection from the head nozzles. The present invention is intended to solve the above-mentioned problems, and its purpose is to achieve high print quality with low ink dot height, good fixing strength, and high thermal stability regardless of the quality of the recording paper. An object of the present invention is to provide a good ink composition. [Means for Solving the Problems] The ink composition of the present invention is ejected from an inkjet recording device at a temperature higher than room temperature. The ink composition consisting of a vehicle and a coloring material is characterized in that it does not contain an antioxidant in an amount of 0.1 to 50% by weight. Further, the vehicle is characterized in that it is a solid or semi-solid that exhibits a melting point or pour point higher than normal temperature; It is characterized by being a mixture of. Further, the antioxidant is selected from the phenolic group and has a melting point of between 50°C and 200°C. (Here, normal temperature is 15℃ to 30℃
) The proportion of antioxidant in the ink composition of the present invention is 0.
．． It is preferably contained between 1 and 50% by weight,
Furthermore, in consideration of the viscosity suitability of the ink suitable for high responsiveness, it is preferable that the content is between 3.0 and 40% by weight. [Function] The ink composition of the present invention is ejected in a uniform solution state by an inkjet recording device and solidified after being printed on recording paper. The antioxidant has a strong supercooling property, which causes a delay in the solidification time of the ink on the surface of the recording paper, causing the ink droplets to flatten and collapse on the surface, and some of the formed dots to be absorbed into the fibers near the surface of the recording paper. Since it solidifies while penetrating the surface, it has scratch resistance, high adhesion, and high print quality. Furthermore, phenolic antioxidants are generally used as radical chain inhibitors (primary antioxidants) to prevent the oxidation of plastics and rubber, and their effect is largely due to their thermal stability in the ink composition of the present invention. Sexuality also improves dramatically. [Example 1] The present invention will be explained below with reference to Examples. The ink composition of the present invention can be prepared by a known method, in which a vehicle component (1) is mixed with a coloring material and a supercooling agent, heated to melt at a temperature higher than the melting point of the vehicle component, preferably 80° C. or higher, and then heated to a temperature higher than 80°C. After heat loss, the composition is made into a homogenized solution, and if necessary, it is filtered through a filter in a high-temperature molten state, and then cooled.6 Physical properties of the ink include operating temperatures ranging from approximately 80°C. The ink viscosity at a temperature of 120°C is determined to be 15.0 milliPascal seconds (mPa,
s) The following is required, and in order to achieve even higher response (2)
~7.0 mP for achieving response of 3 KHz or higher)
a, s to 2.0 mPa, s is more preferable 0 surface tension affects meniscus formation near the nozzle, and 50 dyne
/cm or less is preferable, and more preferably 35 dyne/cm or less is more preferable in order to flatten the dots in the supercooled state of the ink on the recording paper ball after printing and promote permeability. Solid or semi-solid vehicles exhibiting a melting point or pour point above normal temperature include, for example, carnauba wax, paraffin, paraffin wax, microcrystalline wax, synthetic wax, fatty acids. There are solid waxes selected from fatty acid amides, aromatic amides, aromatic sulfonamides, etc., semi-solid petrolatum, petrolatum, lanolin wax, and liquid paraffin is selected as a vehicle that is liquid at room temperature. . Specifically, (paraffin) n-paraffin and isotype paraffin (paraffin wax) with carbon numbers from 23 to 32 No. 115, 120, 125.130° 135.14
0,150.155 HNP-3,9,10, SP (
SP) -0145,1035°3040,3035. 01 l O (Microcrystalline wax, others) Hi-Mitsuku 2045.1045, Cartowax-3025, 3735° (all manufactured by Nippon Seiro ■) (Synthetic wax) Stearon, decanediol. Monostearin, dodecanediol (fatty acid), lauric acid, valmitic acid, stearic acid, behenic acid,
Brassic acid (fatty acid amide) Erucic acid amide, lauric acid amide, stearic acid amide, palmitic acid amide, behenic acid amide, brassic acid amide, oleic acid amide, Amide HT-P, C (manufactured by Lion Kiki) Fatty acid amide-5, T, P, 0 (manufactured by Kao ■) (Aromatic amide, aromatic sulfonamide) para-toluene sulfonamide, ortho-toluene sulfonamide [liquid paraffin] High White-70,350 (Nippon Oil (for commercial use) Silcol P-55 ((manufactured by Matsuzai Petroleum Research Institute), etc. In addition, two or more types of these may be mixed depending on the case. Also, as a phenolic antioxidant, it is suitable for use in high-temperature environments such as cars as printed materials. Considering storage stability to avoid ink bleeding at the bottom and sticking to the laminate, etc., a material with a melting point of at least 50°C is selected.The maximum melting point is 200°C or less depending on the heating condition of the head. is desirable, and more desirably 150°C or less.Specifically, Monophenol Sumilizer BHT (m, p, 69°C) (2,6-di-t-butyl-P-cresol) (manufactured by Injection Kagaku FM) Orient BHA (m, p, 57°C) (butylated hydroxyanisole) (manufactured by Orient Chemical Co., Ltd.) Irganox 1107 6 (, p, 50-53°C) (octadecyl-3-(3,5-di-t) -butyl-4-
Bitroxyphenyl) propionate) (manufactured by Ciba Geigy) Bisphenol-based ANTAGE W-400 (m, p, 120°C) (2,2'-methylene-bis-(4-methyl-6-t-
Butylphenol)) (manufactured by Kawaguchi Chemical ■) Antage W-500 (m, p, 119℃) (2,2°-methylene-bis-(4-ethyl-6-t-
butylphenol)) (manufactured by Kawaguchi Chemical ■) Sumilizer WX (m, p, 150℃) (4,4'-
Thiobis-(3-methyl-6-t-butylphenol)
) (manufactured by Inu Kagaku ■) Polymer phenolic Irganox 1222 (m, p, 50-53℃) (octadecyl-3-(3,5-di-t-butyl-4-
(bitroxyphenyl) propionate)) (manufactured by Ciba Geigy) Dopanol CA (m, p, 185-188°C) (1,1,3-tris-(2-methyl-4-hydroxy-5-t-butylphenyl) butane) (1, C, 1, manufactured by Co., Ltd.), etc. Moreover, two or more types of these may be mixed depending on the case. Moreover, as the coloring material, an oil-soluble dye having heat resistance and water resistance is selected. in particular. [Black Dye] C, 1, Solvent Black 3, 22.23C,! , Acid Black 123 Nigroshin Sumiplast Black-G (BKG), '3B (Su
miplast Black GiBKGl, 3BAl
(manufactured by Inu Kagaku Kogyo ■) Sumisol Black-ARsol (Sumisol Black ARsol, l (
Same as above) GAI Black DT (J, 1.Black DT) (Same as above) [Yellow dye] C, 1, Solvent Yellow 19.21.61.80 Eisen Spiro] / Yellow G RH Special fAi
zen 5pilon Yeilow GR)l 5p
ecfal) (manufactured by Odugaya Chemical Industry) Sumiplast Yellow-GG, FC (S+l11iplast Yellow GG,
PCI (manufactured by Inu Kagaku Kogyo Co., Ltd.) [Red, magenta dye] C, R, Solvent red 8.49.81.82.83.84゜too, 109.121 C, 1, Disperse red 9 Sumiplast red -A3.3B, FB (Sumipl
ast Red AS, 3B, FBI (Injection Chemical Industry (use rack) Aizensbiron Red〇EH Special (Aize
n 5pilon Red GE)l 5special
) (Odogaya Chemical Industry (use rack) [Blue, cyan dye] C,!, Solvent Blue 11.12.25.36.55.73 Sumiplast Blue 3R, BG (Su+5iplast BLUE 3R1BGI
(Manufactured by Inu Kagaku Kogyo Co., Ltd.) Sumiplast Turquoise B
lue Bl (same as above) [Complementary color dye 1 Aizen Violet C-RHiAizen
5pilon Violet C-RHI (manufactured by Odogaya Chemical Industry (#@)) Aizens Violet Yellow C-GNH New (Aize
n 5pilon Yellow C-GNHn
ewl (same as above) Aizen Methyl Violet Ba5e
l (same as above) Aizen Crystal Violet Powder (Aizen
Crystal Violet powder (same as above) Aizen Methyl Violet Pure Special (Aizen Methyl Violet p
ure 5special (same as above) Aizen Victoria pure Blue BOH conch (Aizen Victoria pure Blue
BOHconc, 1 (same as above) Aizen Green C-G11 (same as above) Aizen S, P, T Orange 61
(Same as above) etc. The amount of the coloring material added is preferably 1000% by weight or less, and more preferably 5.0% by weight or less in consideration of flight stability and appropriate viscosity under high response of the head. In addition, two or more types of dyes can be appropriately mixed and used for adjusting the color tone. Next, specific examples of the above components will be shown. Example 1 Composition Weight % Color Material: Solvent Black 23 3.0 Vehicle:) INF-960.0 Stearic acid amide 7.0 Antioxidant Nilganox 1076 30.0 The above acid mixture was melted at 120°C, After heating and stirring for an hour, the molten state was filtered under pressure using a Teflon membrane filter with a pore size of 5 microns.
The viscosity at 0°C is 7.0 mPa, and the surface tension is 27.
An ink composition of 5 dyne/cm was obtained. Next, a known ink-on-demand type inkjet printer head compatible with heat-melting ink was kept at 120°C, and the ink composition shown in Example 1 was filled into it, and the inkjet printer head was used to print on general high-quality paper, bond paper, PPC paper, etc. After performing bit image printing, character printing, etc., the Al-A3 was evaluated as described below. In addition, the ink was evaluated on A4 paper with thermal stability. (At) Printing abrasion resistance: After printing on various types of recording paper, the presence or absence of stains caused by rubbing the printed surface with tissue paper is evaluated based on the elapsed time after printing. ・No stains after 10 seconds ・・・Suitable (0)・20
-No occurrence after 30 seconds... Appropriate (0) - Occurrence after 30 seconds or more - Unsuitable (x) When classified and evaluated, all were rated as ``Appropriate'', although there were slight differences depending on the paper quality.
That was it. (A2) Printed matter blocking property: After stacking blank recording paper on top of the recording paper at a high temperature of 50°C and leaving it under pressure from above for 24 hours, the ink smeared on the recording paper surface and the stacked recording paper Check for ink transfer to. - No ink bleeding, no ink transfer - Appropriate (0) - Ink bleeding, ink transfer - Unsuitable (x) As a result of the classification and evaluation, the dot diameter before leaving was the same as before, no ink bleeding occurred, and the ink did not bleed. No transcription was confirmed either. (A3) Ink dot flatness: Measure the height of the ink dot on the recording paper and evaluate its adhesion to the recording paper.Dot height is 5 microns or less and adhesion is sufficient.
... Suitable (0) - Dot height is 5 to 10 microns and adhesion is sufficient...
- Appropriate (0) - Dot height is higher than 10 microns and adhesion is insufficient... When classified and evaluated by unsuitable (x), all were ``suitable'' or higher. Dot reproducibility based on three evaluation results. Printed matter with good abrasion resistance was obtained. (A4) Ink thermal stability: The ink was placed in a Pyrex glass container and kept at 150° C. for 1000 hours, and evaluated by the increase in viscosity. Viscosity increase up to 20%...Suitable (0) Viscosity increase up to 30%...Suitable (0) Viscosity increase 30%
Exceeding...Unsuitable (×) Example 1 in this evaluation
The initial viscosity of the ink was 7.0mPa,s (110℃)
The pressure was reduced to 8.3 mPa, s, and there was no problem with ink ejection. Ink compositions having the compositions shown in Table 1: Examples 2 to 8 were obtained in the same manner as in Example 1. The dough is based on the specific examples of the vehicles described in Wj) and shows seven combinations with different amounts of antioxidant and fi types. Among these, in Example 4, the main component of the vehicle used is semi-solid or liquid at room temperature, so due to the synergistic effect with the antioxidant, the colorant component remains on the surface of the recording paper and selectively penetrates into the paper. showed the effect of In Examples 2 to 8, Al-
When A4 was evaluated, the results shown in Table 2 were obtained. Comparative Example Ink compositions of Comparative Examples 1 to 3 having the compositions shown in Table 1 were prepared in the same manner as in Example 1. These comparative examples were also evaluated for A1-A4 in the same manner as in Example 1, and the results shown in Table 2 and below were obtained. Comparative Example 1 Since more than 50% of the antioxidant was used in the vehicle, the cooling solidification on paper deteriorated significantly, and in terms of print abrasion resistance (evaluation AI), it took more than 120 seconds for the dots to solidify.
Moreover, the evaluation of blocking property (evaluation A2) was unsuitable. Comparative Example 2 Since it does not contain an antioxidant but uses a supercooled substance, the print condition has good scratch resistance, blocking properties, and ink dot flatness, but the ink stability (rating A-
In 4), the viscosity was 7.5 mPa,s, but 1
The pressure increased by 5 mPa,s (100%), which was inappropriate. Comparative Example 3 Ink flatness during printing (evaluation A3) because it does not contain antioxidants and does not use supercooled substances
All the printed dots were solidified only on the surface of the recording paper, and the fixation to the paper was incomplete, and the printed dots peeled off when the printed surface was rubbed, which was unsuitable. In addition, regarding the ink stability (evaluation A4), the viscosity of the ink which was 8.3 mPa, s increased to 13.6 mPa, s (64%), which was unsuitable. Note that the present invention is not limited to the above embodiments. [Effects of the Invention] As described above, ink is ejected from an inkjet recording device under conditions higher than room temperature. The ink composition consisting of a vehicle and a coloring material is characterized by containing an antioxidant selected from phenols in an amount of 0.1 to 50.0 weight percent, so that the fixing strength is increased regardless of the quality of the recording paper. is high<1i4tli! It has the effect of providing good printing with good dot reproducibility and dot reproducibility, and also has the effect of providing excellent thermal stability of the ink. Furthermore, by using the antioxidant used in the present invention, it is possible to increase the solubility of the coloring agent in the vehicle, and it has the special effect of increasing the printing rate of recorded matter.

Claims (4)

[Claims] (1) An ink composition comprising a vehicle and a coloring material that is ejected from an inkjet recording device at a temperature higher than room temperature and containing an antioxidant in an amount of 0.1 to 50% by weight. . (2) The ink composition according to claim 1, wherein the vehicle is a solid or semisolid having a melting point or pour point higher than room temperature. (3) The ink composition according to claim 1, wherein the vehicle is a mixture of a solid or semi-solid having a melting point or pour point higher than room temperature and a liquid at room temperature. (4) Claim 1, characterized in that the antioxidant is selected from phenolics and has a melting point between 50°C and 200°C.
The ink composition described.