GB2123019A

GB2123019A - Ink composition for ink-jet recording and method of use thereof

Info

Publication number: GB2123019A
Application number: GB08315365A
Authority: GB
Inventors: Takao Abe; Shigehiro Kitamura
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 1982-06-07
Filing date: 1983-06-03
Publication date: 1984-01-25
Also published as: DE3320373A1; GB8315365D0

Abstract

An ink composition for ink-jet recording which dries quickly after use, but is storage-stable and non- corrosive, forming uniform droplets, contains at least one polyoxyethylene alkylphenyl ether of formula (I) and at least one compound selected from among aliphatic polyvalent alcohols and derivatives thereof: <IMAGE> wherein R1 is an alkyl group having 3 or more carbon atoms; R2 and R3 are each a hydrogen atom or an alkyl group; and when R2 and R3 are hydrogen atoms, R1 has at least one secondary or tertiary carbon atom; p is an integer of 3 or more. During recording, a pressure chamber that is deformable by an electromechanical transducer is filled with the ink and an electrical drive pulse is applied to the electromechanical transducer to displace inwardly the wall of the pressure chamber and suddenly decrease its internal volume, whereby a predetermined quantity of ink is ejected from the nozzle toward the recording medium, thereby recording intelligence patterns such as alphanumeric characters and graphical displays on the recording medium.

Description

SPECIFICATION Ink composition for ink-jet recording and method of use thereof The present invention relates to an ink composition for ink-jet recording and a method thereof.

More particularly, the invention relates to an ink composition adapted to a recording method in which the ink is ejected from a nozzle by a sudden reduction in the internal volume of the ink chamber, as well as an ink-jet recording method using such ink composition.

Ink-jet recording is a method of recording information on a recording medium by directing controlled amounts of ink droplets onto the medium without causing a recording head to make any impact against it. Because of various advantages of this method including silentness, high-speed recording and compatibility with plain paper, ink-jet recording has become increasingly popular and is typically used in printers which comprise computer terminals.

Three basic methods of ink-jet recording are known. In one method, ink droplets are ejected by a sudden reduction in the internal volume of a container, or by forcing or drawing the ink out of the chamber at a constant pressure. In another method, ink droplets are ejected from a nozzle by being accelerated in an electrostatic field formed between the nozzle and an opposite electrode in response to a signal voltage. In the third method which is usually known as the ink mist process, an ink mist is produced by ultrasonic vibrations.

The ink for use in this ink jet printing technique must meet the following requirements: (1) it does not plug the nozzles on a recording head; (2) it has suitable physical properties to provide the desired injection characteristics (e.g. flight stability and frequency response); (3) it does not corrode any material that contacts it; and (4) it can be stored for an extended period without deterioration.

After it is printed on a recording medium, the ink should satisfy the following requirements: (5) it dries quickly; (6) it provides intelligence patterns of good quality; and (7) it produces a recorded image that has a low tendency to deteriorate (e.g. high resistance to light and water).

Some of these requirements are conflicting; for example, the first requirement that the ink does not dry easily is incompatible with the fifth requirement that the ink printed on the recording paper should dry as soon as possible. It is therefore very difficult to prepare an ink composition that satisfies all of the seven requirements, and more often than not composition of one, these requirements have been met by means other than the composition of the ink itself. For example, both requirements 1 and 5 can be fulfilled by equipping the printer with a dryer or by using a recording paper made of an inkabsorbing material. However, the use of the dryer adds to the size of the printer, is not economical from the energy point of view, and requires a special type of recording paper.

While several attempts have been made to improve the ink composition per se, none have proved to satisfy all of the seven requirements listed above. For example, an oily ink has been proposed to satisfy the requirement for quick dryability of (5). True this oily ink dries quickly, but it does not have good injection properties, nor does it provide intelligence patterns of good quality. In other words, the oily ink does not fulfill the second and sixth requirements. Japanese Patent Application (OPI) No.

57862/81 (the symbol OPI as used herein means an unexamined published Japanese patent application) proposes an ink composition that dries quickly by dissolving the components of the recording paper. However, this ink dissolves or otherwise adversely affects the part of the printer which is contacted by the ink and hence it does not meet requirement (3). Furthermore, the very purpose of meeting requirement (5) is not fully attained, and intelligence patterns of good quality (requirement (6)) cannot always be obtained either.

Another ink composition claimed to be "quickly dryable" has been proposed and it consists of a dye, a wetting agent, a surfactant and water. The combination of conventional wetting agents and surfactants may not have notably adverse effects on the other requirements, but the fact is the fifth requirement (quick dryability) or the sixth requirement (intelligence patterns of good quality) cannot be fully met. This is because the ink has an insufficient degree of penetration.

We have made various studies to develop a practically feasible ink composition for ink-jet recording that has an adequate penetrating power and well satisfies the requirements for quick drying and providing intelligence patterns of good quality. As a result, we found a surfactant that could be incorporated in an ink composition to provide it with these desired properties. The present invention has been accomplished on the basis of this finding.

One object of the present invention is to provide an ink composition for ink-jet recording that dries quickly on a recording paper.

Another object of the present invention is to provide an ink composition for ink-jet recording that provides intelligence patterns of good quality.

Still another object of the present invention is to provide an ink composition for ink-jet recording that has the desired characteristics of injection from a nozzle.

A further object of the present invention is to provide a method of ink-jet recording that can be used advantageously with the above described ink composition.

These objects of the present invention can be achieved by an ink composition for ink-jet printing that contains at least one compound selected from among the polyoxyethylene alkylphenyl ethers of formula (I) and at least one compound selected from among aliphatic polyvalent alcohols and derivatives thereof (such ink composition is hereunder referred to as the ink composition of the present invention): Formula (I)

(wherein R1 is an alkyl group having 3 or more carbon atoms, such as a propyl, butyl, amyl, octyl, nonyl or dodecyl group;R2 and R3 are each a hydrogen atom or an alkyl group such as a methyl, ethyl, propyl, butyl, amyl, octyl, nonyl or dodecyl group; if both R2 and R3 are hydrogen atoms, R1 has at least one secondary or tertiary carbon atom; p is an integer of 3 or more.) In a preferred embodiment, formula (I) has at least one secondary or tertiary alkyl group. It is also preferred that at least one of Ra, R2 and R3 be an alkyl group having 3 to 12 carbon atoms. It is further preferred that said aliphatic polyvalent alcohol be glycol, diethylene glycol or triethylene glycol. In another preferred embodiment, the ink composition has a compound of formula (all): Formula (II) CnH2n+1 OXCH2CH20 XH wherein 2~m~6, and and m+1 < n < m+3.

In a preferred embodiment of the method of ink-jet recording according to the present invention, a pressure chamber that communicates with a nozzle and at least part of the wall surface of which is deformed by an electromechanical transducer is filled with an ink composition containing at least one compound selected from among the polyoxyethylene alkylphenyl ethers of formula (I) indicated below and at least one compound selected from among aliphatic polyvalent alcohols and derivatives thereof; an electrical drive pulse is applied to said electromechanical transducer to inwardly displace the wall of said pressure chamber and to suddenly decrease its internal volume so that a predetermined quantity of the ink composition in said pressure chamber is ejected from the nozzle toward the recording medium in the form of at least one ink droplet.

Fig. 1 is a schematic diagram showing one embodiment of the ink-jet recorder using the ink of the present invention.

The compounds of formula (I) according to the present invention provide an ink composition that has high penetrating power and which hence dries quickly and enables the printing of intelligence patterns of good quality.

Typical examples of the polyoxyethylene alkylphenyl ether of formula (I) are listed below: I-7

p = 4-10 I-2

p = 6-12 I-3

p = 7-13 1-4

p = 9-15 I-5

p = 8-14 1-6 1-7 1-8 1-9 I-10 I-li I-12 1-13 1-14 1-15 1-16 I-17 I-18

p = 12-18 p = 12-18 p = 5-11 p = 7-13 p = 4-10 p = 6-12 p = 7-13 p = 9-15 p = 8-14 p = 5-11 p = 7-13 p f 9-14 p = 9-15 1-19 1-20 1-21 1-22 1-23 1-24 1-25 1-26 1-27 1-28

p = 3-8 p = 3-8 p = 4-10 p = 4-10 p = 4-8 p = 5-10 p = 5-11 p = 6-12 p = 6-12 p = 6-12 These compounds bring about the intended results whether they are used alone or in combination.

The polyoxyethylene alkylphenyl ethers according to the present invention are known and can be easily produced by known methods. Some of these compounds are easily available as commercial products. For example, compound I-11 listed above is commercially available under the trade name Octapol 60, 80 or 100 from Sanyo Chemical Industries, Ltd., NIKKOL OP-i 0 from Nikko Chemicals K.K.,TRlTON X-l00from Rohm and Haas Company, or Emulgen-810 from Kao-Atlas Company, Ltd.

Compound 1-12 is available under the trade name NIKKOL NP-5, NP-7,5 or NP-10 from Nikko Chemicals K.K., and compound 1-13 is available under Dodekapol 90 or 120 from Sanyo Chemical Industries, Ltd.

The ink composition for ink-jet printing that contains conventional surfactants is disadvantageous in that it forms a scum around the periphery of nozzles on the recording head. This problem is advantageously avoided by using as a surfactant a compound of formula (I), especially when R1 is an alkyl group having 3 to 5 carbon atoms; R2 and R3 are each a hydrogen atom or an alkyl group having 1 to 4 carbon atoms; when both R2 and R3 are hydrogen atoms, R1 has at least one secondary or tertiary carbon atom.

The tips of the nozzles on the recording head always remain wettable by ink. The periphery of each nozzle becomes wet most markedly when the ink is supplied to the recording head under pressure, but the same phenomenon occurs to some extent in the "negative pressure" method. An ink scum deposited on the nozzle tip has great adverse effects on the subsequent recording cycles. Stated more specifically, ink droplets cannot be continuously ejected at a predetermined time interval. At the same time, the droplets are not ejected in the right direction and cannot be deposited on the recording paper to form a predetermined intelligence pattern. If the printer is shut down for a certain period with the ink scum left on the nozzle tip, it dries up and sticks firmly to the nozzle tip.This causes adverse effects on the injection characteristics of ink droplets after restarting the printing operation, and the quality of intelligence patterns will be markedly reduced. In an extreme case, the dry ink deposit plugs the nozzles and makes further ink ejection impossible.

In this respect, the formation of an ink scum around the tip of a nozzle can be effectively prevented by using compounds 1-1, 1-8, 1-10, 1-15 and 1-19 to 1-28 in the ink composition of the present invention.

The compounds of formula (I) are preferably used in an amount of from 0.5 to 15 parts on the basis of the total weight of the ink composition. If their amount is less than 0.5 part by weight, the ink composition may sometimes fail to dry quickly, and if the amount is more than 15 parts by weight, no further increase in the drying speed can be achieved.

The ink composition of the present invention also contains an aliphatic polyvalent alcohol. It is known to use these compounds in ink for ink-jet printing as wetting agents, but it is entirely unexpected that they exhibit good results when they are combined with the polyoxyethylene alkylphenyl ethers of formula (I). Particularly good results are obtained from ethylene glycol, diethylene glycol or triethylene glycol. Further trimethylene glycol, tetraethylenglycol, 1 ,4-butanediol, 1,5pentandiol, thiodiethanol, propylene glycol, and polyethyleneglycol may also be used as a wetting agent.

These wetting agents are preferably used in an amount of from 5 to 90% by weight of the ink composition. If their amount is less than 5 wt%, the ink evaporates so rapidly that it may plug the nozzle tip, and if the amount exceeds 90 wt%, the ink viscosity may become excessively high. A particularly preferred range is from 30 to 80 wt% of the ink composition.

The ink composition of the present invention may further contain a compound of formula (II) defined above. Typical examples of this compound are listed below.

11-1 C3H7+OCH2CH2+20H 11-2 C4HgAOCH2CH2+20H 11-3 QH11OCH2CH2+2OH 11-4 C4HgAOCH2CH2+30H 11-5 C5H 110CH2CH2&num;30H 11-6 C6H13+oCH2CH243oH 11-7 C5H 11&num;OCH2CH2&num;;40H 11-8 C6H130CH2CH24OH II-9 C7H15#OCH2CH2#4OH II-10 C6H13#OCH2CH2#5OH II-11 C7H15#OCH2CH2#5OH II-12 C8H17#OCH2CH2#5OH II-13 C7H15#OCH2CH2#6OH II-14 C8H17#OCH2CH2#6OH II-15 C9H19#OCH2CH2#6OH Particularly preferred compounds are such that n is equal to m+2, and illustrative compounds satisfying this relationship are 11-2, -5,-8, -11 and -14.

The compounds of formula (II) may be used in any amount, but a preferred range is from 1 to 10 wt% of the ink composition. If their amount is less than 1 wt%, the ink does not have sufficient penetrating power to dry quickly, and if the amount exceeds 10 wt%, the ink has a tendency to attack the ink container or printer.

The compounds of formula (II) may be used either alone or in combination, and in the latter case, the total amount of the compounds should be in the range of 1 to 10 wt% of the ink composition.

The ink composition of the present invention may also contain, as the penetration accelerator, dimethyl sulfoxide, diethanol amine, N-hydroxyethyl-2-pyrrolidone and α-pyrrolidone, which may be used in any amount, but preferably in the range of from 10 to 60 wt% of the ink composition.

The ink composition of the present invention contains as the essential components water, the polyoxyethylene alkylphenyl ether of formula (I), and the wetting agent consisting of at least one compound selected from the aliphatic polyvalent alcohols. The ink composition optionally contains the compound of formula (II) or dimethylsulfoxide, and it may also contain other additives if they are necessary. Typical additives are dyes which are important for printing purposes. The ink composition of the present invention may use any water-soluble dye.

The water-soluble dyes that can be used in the present invention are direct dyes, basic dyes, reactive dyes and acidic dyes. The amount of these dyes added to the ink composition of the present invention is determined by the color intensity of intelligence patterns to be printed on the recording medium, which in turn depends on the interaction between the ink and the recording medium. In other words, the addition of these dyes to the ink is determined by their relationship with the recording medium. Therefore, a yellow, magenta, cyan or black ink composition may be prepared by incorporating preferably 0.2 to 1 5 parts, more preferably 0.5 to 7 parts, of one or more water-soluble dyes on the basis of the total weight of the ink composition.

Illustrative direct dyes, basic dyes, reactive dyes and acidic dyes that can be used in the present invention are disclosed in Japanese Patent Application (OPI) No. 89534/74. Other examples are listed below for each type: (I) Direct dyes Cl. Direct Yellow 27 (C.l.13950) " " " 28 (C.I.19555) " " " 33 (C.I.29020) 39 58 86 100 Red 63 " " " 75 (C.I.25380) " " " 79 (C.I.29065) " " " 80 (C.I.35780) " " " 83 (C.I.29225) 99 220 224 " " " 47 (C.I.25410) " " " 48 (C.I.29125) " " " 51 (C.I.27905) 90 94 " " Blue 1 (C.I.24410) 8 " " " 71 (C.I.34140) " " " 76 (C.I.24411) C.I..Direct Blue 78 (C.I.34200) " " " 80 " " " 86 (C.I.74180) " " " 90 " " " 106 (C.I.51300) " " " 108 (C.I.51320) " " " 123 (C.I.26705) " " " 163 (C.I.33560) " " " 165 " " Black 19 (C.I.35255) " " " 32 (C.I.35440) " " " 38 (C.I.30235) " " " 71 (C.I.25040) " " " 74 (C.I.34180) " " " 75 (C.I.35870) " " " 112 " " " 117 " " " 154 (II) Acidic dyes C.I.Acid Yellow 17 (C.I.18965) " " " 19 " " " 25 (C.I.18835) " " " 29 (C.I.18900) " " " 38 (C.I.25135) " " " 49 " " " 59 " " " 61 " " " 72 " " Red 1 (C.I.18050) " " " 8 (C.I.14900) " " " 32 (C.I.17065) " " " 37 (C.I.17045) " " " 42 (C.I.17070) " " " 57 " " " 115 (C.I.27200) " " " 119 " " " 131 " " " 133 (C.I.17995) " " " 134 (C.I.24810) " " " 154 (C.I.24800) " " " 186 (C.I.18810) " " " 249 (C.I.18134) " " " 254 " " " 256 " " Violet 11 (C.I.17060) " " " 34 (C.I.61710,61800) " " " 75 " " Blue 29 (C.I.20460) " " " 126 " " " 171 " " " 175 " " " 183 " " Black 1 (C.I.20470) " " " 24 (C.I.26370) " " " 26 (C.I.27070) " " " 48 (C.I.65005) " " " 52 (C.I.15711) " " " 58 " " " 60 " " " 107 " " " 109 " " " 119 " " " 131 " " " 155 (III) Reactive dyes C.l.Reactive Blue 7 (C.I.74460) 14 15 18 21 25 Yellow 1 " " " 2 (C.I.18972) " " " 3 (C.I.13245) 13 14 15 17 (C.l.18852) Red 2 " " " 6 (C.I.17965) 11 23 36 " " Violet 2 (C.l.18157) 4 8 9 (IV) Basic dyes C.l. Basic Yellow 11 (C.I.48055) 14 21 32 " " Red 1 (C.I.45160) 2 " " 2 (C.I.50240) " " " 9 (C.I.42500) " " " 12 (C.I.48070) " " " 13 (C.I.48015) " " Violet 3 (C.I.42555) " " 7 (C.I.48020) " " " 14 (C.I.42510) " " Blue 3 (C.I.51005) " " " 9 (C.I.52015) " " " 24 (C.I.52030) " " " 25 (C.I.52025) Other dyes that can also be incorporated in the ink composition of the present invention are chelate dyes and azo dyes, the latter being used in photosensitive materials processed by the "silver dye bleaching method" (e.g. Cibachrome by Ciba-Geigy AG).For details of the chelate dyes, reference can be had to British Patent No. 1,077,484. For details of the azo dyes used in photosensitive materials processed by the "silver dye bleaching method", reference may be had to British Patent Nos.

1,039,458, 1,004,957, 1,077,628, and U.S. Patent No. 2,612,448.

If the ink composition of the present invention is to be stored for an extended period, it may contain preservatives or mold inhibitors that prevent or inhibit the growth of bacteria or molds within the ink. While many preservatives are known to be effective for this purpose, a particularly preferred compound is 1,3,5-hexahydrotriazine derivative (Bacillat 35 by Hoechst Aktiengesellschaft).

In order to control the surface tension that governs the wettability of the recording paper with the ink composition of the present invention, the latter may contain a surfactant other than the polyoxyethylene alkylphenyl ether of formula (I). Any surfactant may be used except for those which have extremely low solubilities or which interact with the dyes.

The pH of the ink composition of the present invention may change if it absorbs carbon dioxide in the air while it is stored in the container or retained within the nozzle. To prevent this phenomenon, the ink composition may contain a pH buffer selected from among many inorganic or organic compounds.

Suitable pH buffers are carbonate salts such as sodium carbonate and potassium carbonate. For practical purposes, these pH buffers are used in an amount of 0.1 to 5 wt%, preferably 0.1 to 2 wt%, of the total ink composition.

The ink composition of the present invention may also contain a chelate agent in order to mask any undesired metals or metal ions. Typical chelate agents include sodium gluconate, ethylenediamine tetraacetic acid (EDTA), disodium ethylenediaminetetraacetate, trisodium ethylenediamine tetraacetate, tetrasodiu m ethylenediaminetetraacetate, and sodium diethylenetriaminopentaacetate.

For practical purposes, these chelate agents are used in an amount of 0.1 to 5 wt%, preferably 0.1 to 2 wt%, of the total ink composition.

The method of ink-jet recording using the ink composition of the present invention is hereunder described by reference to Fig. 1, which is a schematic representation of an apparatus 1 adapted to record information on a recording medium 2 which is stretched between a supply roller 3 and a take-up roller 4 to move in the direction indicated by the arrow. It should be understood that relative movement between the apparatus 1 and the recording medium 2 may be in any suitable manner, with actual movement taking place either by the apparatus 1, the recording medium 2 or both. In the embodiment shown, the recording medium 2 is moved.

The apparatus 1 includes an ink source 6 which is a reservoir for the ink composition of the present invention. Ink source 6 feeds through a tube 7 to an ink drop projecting means or printing head 8. An electronic pulse generator 9 applies pulses to the printing head 8 through an appropriate transmission means 11, such as wires. The generator 9 does not operate at a resonant frequency, rather it calls for a droplet according to the predetermined pattern to be printed.

The apparatus 1 also includes a suitable plate 1 7 that is capable of deflecting into a projection chamber 1 6 upon receiving an electrical signal from the generator 9. The plate 1 7 is an assembly of two piezoelectric crystals 1 9 and 20 bonded together: The electrical connection ii from the generator 9 applies a voltage across the two faces of the plate 1 7 so that the upper segment 1 9 contracts and the lower segment 20 expands, so the entire plate 1 7 flexes inwardly into the chamber 1 6. The plate assembly is attached to the head 8 in such a manner as to permit minute rotations at the edge of the assembly. Such attachment can be made using a wide variety of epoxy adhesives.The inward deflection of the plate 1 7 is shown by the one-iong-and-two-short dashed line in Fig. 1.

Careful positioning of the medium relative to apparatus 1, or vice versa, results in impingement of droplets in a predictable pattern according to signals generated by the electronic pulse generator 9, which is determined by the information to be printed. For the best recording of information, the droplets should be of a precise and predictable shape and volume. That is, each droplet must be precisely the same as the other droplets and it must closely follow the electronic signals from the generator 9 so that equally spaced signals give equally spaced droplets.

The droplet 1 2 is discharged from the printing head 8 by the sudden reduction of volume in the chamber 1 6. This sudden reduction in volume is accomplished by deflecting the plate 1 7 into the chamber 1 6 to displace sufficient ink to form a droplet 12. The deflection must be sudden enough to impart sufficient kinetic energy to the fluid in a nozzle 1 8 to accelerate a portion of it beyond the escape velocity.

In the apparatus 1, upon receiving a pulse from the generator 9, the printing head 8 discharges and projects a single discrete droplet 12 of ink from an orifice 14. Each electrical pulse generates a single droplet, independently of any previous signals, with the volume of the drop being controlled by the applied electrical pulse. For accurate recording of information on the recording medium 2, the droplets 12 from a line 13 on the medium 2 by following a substantially straight trajectory as the medium is moved past the printing head 8. After the droplet has been ejected, the plate returns to its normal position and the meniscus of the liquid is drawn back in the orifice approximately one droplet diameter. This liquid must be replaced before the printer can be activated again to eject another droplet, and the capilary action of the fluid in the orifice provides the required force.

The ink composition of the present invention is most preferably used with the on-demand type ink-jet printing system, although this is not the only system to which said ink composition can be applied. For details of the on-demand type ink-jet printing system as well as modifications thereof, see U.S. Patent Nos. 3,946,398, 4,189,734,4,144,537, and Japanese Patent No.35936/79.

The present invention is hereunder described in greater detail by reference to working examples, to which the scope of the present invention is by no means limited.

Example 1 Components Amount (wit%) Diacid Light Yellow 2GP (product of Mitsubishi Chemical Industries Limited) 3.0 Diethylene glycol 50.0 Compound 1-19 (p=3) 2.0 Potassium carbonate 0.2 Bacillat 35 0.2 Distilled water 44.6 The above indicated components were mixed, stirred at room temperature for 3 hours and passed through a membrane filter (TM-1) with a pore size of 0.65 y to form sample No. 1 of the present invention. It had a viscosity of 7.8 cps and a surface tension of 31.1 dyne/cm at 250C.

Example 2 Components Amount (wit%) Nippon Brilliant Pink B conc (product of Sumitomo Chemical Co., Ltd.) 2.0 Ethylene glycol 15.0 Diethylene glycol 40.0 Compound 1-22 (p=5) 1.0 Potassium carbonate 0.2 Bacillat 35 0.2 EDTA tetrasodium salt 0.3 Distilled water 41.3 The above components were mixed and processed as in Example 1 to prepare sample No. 2 of the present invention. It had a viscosity of 8.1 cps and a surface tension of 34.2 dyne/cm at 250C.

Example 3 Components Amount (wtP/o) Sumilight Supra Turquoise Blue conc (product of Sumitomo Chemical Co.; Ltd.) 1.0 Ethylene glycol 15.0 Triethylene glycol 40.0 Compound 1-26 (p=10) 2.0 Potassium carbonate 0.2 Bacillat 35 0.2 EDTA tetrasodium salt 0.3 Distilled water 41.3 The above components were mixed and processed as in Example 1 to prepare sample No. 3 of the present invention. It had a viscosity of 9.7 cps and a surface tension of 30.5 dyne/cm at 250C.

Example 4 Components Amount (wit%) C.l. Direct Black-32 (C.l. 35440) 3.0 Ethylene glycol 35.0 Diethylene glycol 10.0 Triethylene glycol 10.0 Compound 1-22 (p=8) 2.0 Potassium carbonate 0.2 Bacillat 35 0.2 Distilled water 39.6 The above components were mixed and processed as in Example 1 to prepare sample No. 4 of the present invention. It had a viscosity of 6.8 cps and a surface tension of 34.5 dyne/cm at 250C.

Example 5 Components Amount (wt%) C.l. Direct Black-32 3.0 Ethylene glycol 35.0 Diethylene glycol 10.0 Triethylene glycol 10.0 sec-C5H11430 ( CH2CH2O +3H 1.0 Potassium carbonate 0.2 Distilled water 40.8 The above components were mixed and processed as in Example 1 to prepare sample No. 5 of the present invention. It had a viscosity of 6.8 cps and a surface tension of 30.0 dyne/cm at 250C.

Example 6 Components Amount (wt%) Cl. Direct Black-1 9 (Cl. No.35255) 3.0 Ethylene glycol 63.3 Compound 1-1 (p=5) 1.0 Potassium carbonate 0.2 Distilled water 32.5 The above indicated components were mixed, stirred at room temperature for 3 hours, and passed through a membrane filter (TM-1) with a pore size of 0.65 y to form sample No. 6 of the present invention. It had a viscosity of 7.8 cps and a surface tension of 32.0 dyne/cm at 250C.

Example 7 Components Amount (wit%) Diacid Light Yellow 2GP (product of Mitsubishi Chemical Industries Limited) 3.0 Diethylene glycol 50.0 Compound 1-2 2.0 Potassium carbonate 0.2 Bacillat 35 0.2 Distilled water 44.6 The above components were mixed and processed as in Example 6 to prepare sample No. 7 of the present invention. It had a viscosity of 5.80 cps and a surface tension of 34.4 dyne/cm at 250C.

Example 8 Components Amount (wt%) Nippon Brilliant Park B conc. (Sumitomo Chemical Co., Ltd.) 2.0 Ethylene glycol 15.0 Diethylene glycol 40.0 Compound 1-9 1.0 Potassium carbonate 0.2 Bacillat 35 0.2 EDTA tetrasodium salt 0.3 Distilled water 41.3 The above components were mixed and processed as in Example 6 to prepare sample No. 8 of the present invention. It had a viscosity of 8.1 cps and a surface tension of 33.8 dyne/cm at 250C.

Example 9 Components Amount lwtO/oJ Sumilight Supra Turquoise Blue Conc. (Sumitomo Chemical Co., Ltd.) 1.0 Ethylene glycol 15.0 Triethylene glycol 40.0 Compound 1-5 (p=8) 2.0 Potassium carbonate 0.2 Bacillat 35 0.2 EDTA tetrasodium salt 0.3 Distilled water 41.3 The above components were mixed and processed as in Example 6 to prepare sample No. 9 of the present invention. It had a viscosity of 9.7 cps and a surface tension of 30.0 dyne/cm at 250C.

Example 10 Components Amount (wit%) C.I. Direct Black-32 (C.l. 35440) 3.0 Ethylene glycol 35.0 Diethylene glycol 10.0 Triethylene glycol 10.0 Compound 1-3 (Emulgen-910) 2.0 Potassium carbonate 0.2 Bacillat 35 0.2 Distilled water 39.6 The above components were mixed and processed as in Example 6 to prepare sample No. 10 of the present invention. It had a viscosity of 6.8 cps and a surface tension of 31.4 dyne/cm at 250C.

Example 11 Samples Nos. 1 to 10 and the samples prepared in Comparative Examples 1 to 8 (to be described later) were fed to an ink-jet printer of the type shown in Figs. 1 to 3 of U.S. Patent No. 4,1 89,734 and ink droplets were projected onto sheets of plain paper under the conditions shown in Table 1.

Table 1 Printing speed 2,000 dots/sec Static pressure -0.07 psi Pulse peak pressure 25.3 psi Pulse voltage 120 V Pulse width 110,us Orifice diameter 0.003 inch After the recording, about 1 cc of each ink sample was forced out of the nozzle under pressure to see if there remained any ink scum on the nozzle tip. The results are shown in Table 2.

Table 2 Drying Quality of speed on printed Injection Ink Sample No. paper characters characteristics scum 1 less than good good none 3 sec 2 do. do. do. do.

3 do. do. do. do.

4 do. do. do. do.

5 do. do. do.

6 do. do. do. poor 7 do. do. do. poor 8 do. do. do.

9 do. do. do. poor 10 do. do. do. poor Comp. sample 1 more than poor do. present 60 sec 2 less than rather poor present 3 sec poor 3 30-60 sec poor good 4 more than poor do.

60 sec 5 less than rather poor 3 sec poor 6 30-60 sec poor good 7 do. do. do.

8 20-30 sec do. poor As Table 2 shows, sample Nos. 1 to 10 of the present invention dried quickly, provided characters of good quality and exhibited good injection characteristics. Samples Nos. 1 to 4 were particularly good because they left no ink scum on the nozzle tip.

Comparative Example 1 Components Amount (wit%) Cl. Direct Black-1 9 3.0 Glycerin 15.0 Sodium hydroxide 1.2 Distilled water 80.8 The above components were mixed and processed as in Example 1 to prepare comparative sample No. 1. It had a viscosity of 1.8 cps and a surface tension of 62.5 dyne/cm at 250C.

Comparative Example 2 Components Amount lwto/ol C.l. Solvent Blue 55 (Zapon Fast Blue FLE, product of BASF Aktiengesellschaft) 3.0 Diethanolamine 22.0 Butyl Carbitol 75.0 The above components were mixed and processed as in Example 1 to prepare comparative sample No.2. It had a viscosity of 27.1 cps and a surface tension of 30.2 dyne/cm at 250C.

Comparative Example 3 Components Amount (wit%) Cl. Direct Black-1 9 3.0 Ethylene glycol 35.0 Diethylene glycol 10.0 Triethylene glycol 10.0 Tween 20 (polyoxyethylene sorbitan monolaurate, product of Kao-Atlas Company, Ltd.) 1.0 Potassium carbonate 0.2 Distilled water 40.8 -The above components were mixed and processed as in Example 6 to prepare comparative sample No. 3. It had a viscosity of 6.8 cps and a surface tension of 29.4 dyne/cm at 250C. The characters printed with comparative sample No. 3 had marked feathering and dried slowly.

Comparative Example 4 Components Amount (WtO/o) C.l. Direct Black-19 3.0 Glycerin 15.0 Sodium hydroxide 1.2 Distilled water 80.8 The above components were mixed and processed as in Example 6 to prepare comparative sample No. 4. It had a viscosity of 1.8 cps and a surface tension of 62.5 dyne/cm at 250C. The formulation of this comparative sample was the same as that proposed in Japanese Patent Application (OPI) No. 57862/81, and as shown in Table 2, it dried slowly and produced only intelligence characters of poor quality.

Comparative Example 5 Components Amount (wit%) C.I. Solvent Blue 55 (Zapon Fast Blue FLE, product of BASF Aktiengesellshaft) 3.0 Diethanolamine 22.0 Butyl Carbitol 75.0 The above components were mixed and processed as in Example 6 to prepare comparative sample No. 5. It had a viscosity of 27.1 cps and a surface viscosity of 30.2 dyne/cm at 250C. The formulation of this comparative sample was the same as that proposed in Japanese Patent Application (OPI) No. 65270/80. It dried quickly but since it was discharged in excessively large droplets, it produced only intelligence characters of poor quality. In addition, the injection characteristics of the sample were also poor.

Comparative Example 6 Components Amount (wit%) C.l. Direct Black-19 2.5 Glycerin 30.0 Emulgen-909 1.0 Potassium carbonate 0.2 Distilled water 65.8 The above components were mixed and processed as in Example 6 to prepare comparative sample No. 6. It had a viscosity of 3.9 cps and a surface tension of 32.2 dyne/cm at 250C.

Comparative Example 7 Components Amount (wit%) C.l. Direct Black-32 3.0 Formamide 50.0 Emulgen-909 1.0 Potassium carbonate 0.2 Distilled water 45.8 The above components were mixed and processed as in Example 6 to prepare comparative sample No. 7. It had a viscosity of 3.8 cps and a surface tension of 32.0 dyne/cm at 250C.

Comparative samples No. 6 and No. 7 used wetting agents which were outside the scope of the present invention, so they dried slowly and gave only intelligence characters with marked feathering.

Comparative Example 8 Components Amount (wit%) C.l. Direct Black-32 3.0 Ethylene glycol 13.0 Glycerin 30.0 Polyoxyethylene lauryl ether (Emulgen-147 of Kao-Atlas Company, Ltd.) 20.0 Potassium carbonate 0.2 Distilled water 33.8 The above components were mixed and processed as in Example 6 to prepare comparative sample No. 8. It had a viscosity of 28.4 cps and a surface tension of 34.7 dyne/cm at 250C. The formulation of this comparative sample was the same as what was proposed in Japanese Patent Application (OPI) No. 29546/80, but it dried slowly and produced only intelligence characters of poor quality.

Example 12 Components Amount(wt%) Diacid Light Yellow 2GP (product of Mitsubishi Chemical Industries Limited) 3.0 Ethylene glycol 30.0 Dimethyl sulfoxide 30.0 Compound 1-1 (p=5) 1.0 Potassium carbonate 0.2 Distilled water 35.8 The above indicated components were mixed, stirred at room temperature for 3 hours, and passed through a filter (pore size=0.65,u) to prepare sample No. 11 of the present invention. It had a viscosity of 4.7 cps and a surface tension of 31.8 dyne/cm at 250C.

Example 13 Components Amount (wit%) Kayacyl Pure Blue FGA (Nippon Kayaku Co., Ltd.) 1.5 Diethylene glycol 30.0 Dimethyl sulfoxide 40.0 Compound 1-5 (p=8) 1.0 Potassium carbonate 0.2 EDTA tetrasodium salt 0.3 Distilled water 27.0 The above components were mixed and processed as in Example 12 to prepare sample No. 12 of the present invention. It had a viscosity of 5.5 cps and a surface tension of 30.3 dyne/cm at 250C.

Example 14 Components Amount (wit%) C.I. Direct Black-32 (C.I. No. 35440) 3.0 Ethylene glycol 25.0 Diethylene glycol 10.0 Triethylene glycol 10.0 Dimethyl sulfoxide 20.0 Compound 1-3 2.0 Potassium carbonate 0.2 Distilled water 29.8 The above components were mixed and processed as in Example 12 to prepare sample No. 13 of the present invention. It had a viscosity of 6.2 cps and a surface tension of 32.0 dyne/cm at 250C.

Comparative Example 9 Components Amount (wt%) Direct Black-32 3.0 Ethylene glycol 45.0 Compound 1-3 1.0 Potassium carbonate 0.2 Distilled water 50.3 The above components were mixed and processed as in Example 12 to prepare comparative sample No. 9 which contained no dim ethyl sulfoxide. It had a viscosity of 5.7 cps and a surface tension of 33.9 dyne/cm at 25"C.

Comparative Example 10 Components Amount (wit%) C.l. Direct Black-32 3.0 Ethylene glycol 30.0 Dimethyl sulfoxide 30.0 Potassium carbonate 0.2 Distilled water 36.8 The above components were mixed and processed as in Example 12 to prepare comparative sample No. 10. it had a viscosity of 4.6 cps and a surface tension of 47.9 dyne/cm at 250C.

Example 15 Sample Nos. 12 to 14 and comparative samples Nos. 9 and 10 were supplied to an ink-jet printer of the same type as used in Example 11, and ink droplets were discharged onto sheets of plain paper under the same conditions as used in Example 11. The results are shown in Table 3.

Table 3 Ouality of Drying speed on printed Injection Sample paper characters characteristics 11 less than 3 sec very good very good 12 do. do. do.

13 do. do. do.

Comp. Sample 9 3-5 sec some feathering good occurred 10 more than 60 sec poor good Table 3 shows that the ink samples of the present invention were better than the comparative samples with respect to the drying speed and the quality of printed characters.

Example 16 Components Amount (wit%) Diacid Light Yellow 2GP (Mitsubishi Chemical Industries Limited) 3.0 Ethylene glycol 40.0 Compound l-1 (p=5) 1.0 Compound 11-2 5.0 Potassium carbonate 0.2 Distilled water 50.8 The above components were mixed, stirred at 250C for 3 hours and passed through a filter (pore size=0.65 u) to prepare sample No. 14 of the present invention. It had a viscosity of 4.5 cps and a surface tension of 32.1 dyne/cm at 250C.

Example 17 Components Amount (wit%) Kayacyl Pure Blue FGA (Product of Nippon Kayaku Co., Ltd.) 1.5 Diethylene glycol 40.0 Compound 1-5 (p=8) 1.0 Compound 11-2 8.0 Potassium carbonate 0.2 Distilled water 49.3 The components above were mixed and processed as in Example 16 to prepare sample No. 1 5 of the present invention. It had a viscosity of 5.6 cps and a surface tension of 30.6 dyne/cm at 250C.

Example 18 Components Amount (wt%) Direct Black-32 3.0 Ethylene glycol 40.0 Diethylene glycol 10.0 Tdethylene glycol 10.0 Compound 1-3 1.0 Compound 11-2 5.0 Potassium carbonate 0.2 Distilled water 35.8 The components above were mixed and processed as in Example 16 to prepare sample No. 16 of the present invention. It had a viscosity of 8.9 cps and a surface tension of 32.6 dyne/cm at 25 C.

Comparative Example 11 Components Amount {wP/o) Direct Black-32 3.0 Ethylene glycol 45.0 Compound 1-3 1.0 Potassium carbonate 0.2 Distilled water 50.3 The components above were mixed and processed as in Example 16 to prepare comparative sample No. 11 which contained no compound of formula (II). it had a viscosity of 5.7 cps and a surface tension of 33.9 dyne/cm at 250C.

Comparative Example 12 Components Amount (wit%) Direct Black-32 3.0 Ethylene glycol 45.0 Compound 11-2 10.0 Potassium carbonate 0.2 Distilled water 40.3 The components above were mixed and processed as in Example 16 to prepare comparative sample No. 12 which contained no compound of formula (I). It had a viscosity of 5.5 cps and a surface tension of 33.3 dyne/cm at 25 OC.

Example 19 Sample Nows. 15 to 17 and comparative sample Nos. 11 and 12 were fed to an ink-jet printer of the same type as used in Example ii, and ink droplets were projected onto sheets of plain paper under the same conditions as employed in Example 11. The results are shown in Table 4.

Table 4 Quality of Drying speed printed Injection Sample on paper characters characteristics 14 less than 3 sec very good very good 15 do. do. do.

16 do. do. do.

Comp. Sample 11 3-5 sec some feathering good occurred 12 do. do. do.

As is clear from Table 4, the ink samples of the present invention were better than the comparative samples with respect to the drying speed and the quality of printed characters.

Example 20 Components Amount (wit%) C.l. Direct Black-19 (CI. No.35255) 3.0 Ethylene glycol 63.3 Compound 1-1 (p=5) 1.0 Potassium carbonate 0.2 Distilled water 32.5 The components above were mixed, stirred at room temperature for 3 hours and passed through a membrane filter (TM-1) with a pore size of 0.65 to prepare sample No. 17 of the present invention.

It had a viscosity of 7.8 cps and a surface tension of 34.0 dyne/cm at 250C.

Example 21 Components Amount (wt%) Diacid Light Yellow 2GP (product of Mitsubishi Chemical Industries Limited) 3.0 Diethylene glycol 50.0 Compound 1-11 (Octapol 100) 2.0 Potassium carbonate 0.2 Bacillat 35 0.2 Distilled water 44.6 The components above were mixed and processed as in Example 20 to prepare sample No. 18 of the present invention. It had a viscosity of 6.0 cps and a surface tension of 34.4 dyne/cm at 250C.

Example 22 Components Amount (wit%) Nippon Brilliant Pink B conc. (Sumitomo Chemical Co., Ltd.) 2.0 Ethylene glycol 20.0 Diethylene glycol 40.0 Compound 1-12 (NIKKOL NP-7.5) 1.0 Potassium carbonate 0.2 Bacillat 35 0.2 EDTA tetrasodium salt 0.3 Distilled water 41.3 The components above were mixed and processed as in Example 20 to prepare sample No. 1 9 of the present invention. It had a viscosity of 8.3 cps and a surface tension of 31.4 dyne/cm at 250C.

Example 23 Components Amount fWto/o) Sumilight Supra Turquoise Blue conc. (product of Sumitomo Chemical Co., Ltd.) 1.0 Ethylene glycol 15.0 Triethylene glycol 40.0 Compound 1-14 (p=8) 1.0 Potassium carbonate 0.2 Bacillat 35 0.2 EDTA tetrasodium salt 0.3 Distilled water 41.3 The components above were mixed and processed as in Example 20 to prepare sample No. 20 of the present invention. It had a viscosity of 9.7 cps and a surface tension of 30.0 dyne/cm at 250C.

Example 24 Components Amount (wit%) C.l. Direct Black-32 (C.I. 35440) 3.0 Ethylene glycol 35.0 Diethylene glycol 10.0 Triethylene glycol 10.0 Compound 1-13 (Dodecapol 120) 1.0 Potassium carbonate 0.2 Bacillat 35 0.2 Distilled water 39.6 The components indicated above were mixed and processed as in Example 20 to prepare sample No. 21 of the present invention. It had a viscosity of 6.8 cps and a surface tension of 33.6 dyne/cm at 250C.

Example 25 Samples Nos. 17 to 21 and previously prepared comparative samples Nos. 3 to 8 were fed to an ink-jet printer of the same type as used in Example 11, and ink droplets were projected onto sheets of plain paper under the same conditions as employed in Example 11. The results are shown in Table 5.

Table 5 Quality of Drying speed on printed Injection Sample paper characters characteristics 17 less than 3 sec good good 18 do. do. do.

19 do. do. do.

20 do. do. do.

21 do. do. do.

Com. Sample 3 30-60 sec poor do.

4 more than 60 sec do. do.

5 less than 3 sec rather poor poor 6 30-60 sec poor good 7 do. do. do.

8 20-30 sec do. poor As the above data shows, the ink samples of the present invention dried quickly and provided intelligence characters of good quality. Thus, they resolved the two big problems with the conventional ink composition for use in ink-jet printing.

Claims

1. An ink composition for ink-jet printing, at least one polyoxyethylene alkylphenyl ether of formula (I) and at least one compound selected from among aliphatic polyvalent alcohols and derivatives thereof:

wherein R, is an alkyl group having 3 or more carbon atoms; R2 and R3 are each a hydrogen atom or an alkyl group; and when both R2 and R3 are hydrogen atoms, R1 has at least one secondary or tertiary carbon atom; p is 3 or more.

2. An ink composition according to Claim 1 wherein R, is a secondary or tertiary alkyl group.

3. An ink composition according to Claim 1 or 2 wherein R1 is an alkyl group having 3 to 12 carbon atoms.

4. An ink composition according to any preceding Claim wherein R2 and R3 are each an alkyl group having 1 to 12 carbon atoms.

5. An ink composition according to Claim 4 wherein said alkyl group is a secondary or tertiary alkyl group.

6. An ink composition according to any preceding Claim wherein p is 3 to 20.

7. An ink composition according to Claim 1 wherein R, is an alkyl group having 3 to 5 carbon atoms.

8. An ink composition according to Claim 7 wherein R2 and R3 are each a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and if both R2 and R3 are hydrogen atoms, R, has at least one secondary or tertiary carbon atom.

9. An ink composition according to any preceding Claim wherein the aliphatic polyvalent alcohol is ethylene glycol, diethylene glycol or triethylene glycol.

10. An ink composition according to any preceding Claim which further contains dimethyl sulfoxide, N-hydroxyethyl-2-pyrrolidone or a-pyrrolidone.

11. An ink composition according to any preceding Claim which further contains a compound of formula (all): CnH2n+1O+CH2cH20+mH (II) wherein 2~m~6. and m+1 ~n~m+3.

12. An ink composition according to Claim 11 wherein n=m+2.

1 3. An ink composition according to Claim 1 and substantially as hereinbefore described with reference to any of the Examples.

14. A method of ink-jet recording wherein a pressure chamber that communicates with a nozzle and at least part of whose wall surface is deformable by an electro-mechanical transducer is filled with an ink composition according to any of the preceding Claims, an electrical drive pulse is applied to said electro-mechanical transducer to displace inwardly the wall of said pressure chamber and suddenly to decrease its internal volume, whereby a predetermined quantity of the ink composition in said pressure chamber is ejected from the nozzle toward the recording medium in the form of at least one ink droplet.

1 5. A method according to Claim 14 wherein, after an ink droplet has been ejected in response to a single drive pulse, the internal volume of said pressure chamber is restored to the initial equilibrium state of the ink.

1 6. A method according to Claim 14 and substantially as hereinbefore described.