Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/502—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording characterised by structural details, e.g. multilayer materials
  • B41M5/508—Supports
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
  • B41M5/50—Recording sheets characterised by the coating used to improve ink, dye or pigment receptivity, e.g. for ink-jet or thermal dye transfer recording
  • B41M5/52—Macromolecular coatings

Definitions

• the present invention relates to an ink-jet recording medium and to an ink-jet recording method employing an improved recording medium and inks suited for this recording medium to provide good quality records.
• ink-jet recording methods are greatly noticed because of advantages thereof such that high-speed and low- noise recording is possible and color recording is easy.
• ink-jet recording papers include so-called non-sized paper, which is a common paper untreated with size, and a coated paper having a porous ink-absorbing layer on the surface thereof.
• a non-coated paper has drawbacks in that inks on adhering thereto diffuse along fibers thereof and shapes of ink dots are hence disordered, and that recording agents (dyes) penetrate inside the paper, thus the optical density of recorded images being lowered.
• a coated paper has drawbacks in that it is deficient in the feel of common paper since it is a special processed paper, and that, when ink droplets are applied thereon, microscopically ink dots are good in shape and high in optical density, but macroscopically the ink dot diameter varies from part to part of the paper, unevenness of optical density is observed, and the recorded image looks roughened.
• An object of the invention is to correct the above- noted drawbacks of existing ink-jet recording papers and additionally provide an ink-jet recording method which gives good quality image records.
• a first aspect of the invention there is provided use in ink-jet recording of recording medium comprising a base paper and an ink acceptor coated on the base paper, characterised in that the base paper has a basis weight of 50 to 90 g/m 2 and a sizing degree of 5 to 100 seconds.
• an ink-jet recording method in which a recording is made by jetting ink onto a recording medium, characterised in that the recording medium comprises a base paper and an ink acceptor coated on the base paper, the base paper having a basis weight of 50 to 90 g/m 2 and a sizing degree of 5 to 100 seconds, and that the water content of the ink is in the range of 10 to 90 % by weight.
• an ink-jet recording method in which a recording is made by jetting ink onto a recording medium, characterised in that the recording medium comprises a base paper and an ink acceptor coated on the base paper, the base paper having a basis weight of 50 to 90 g/m 2 and a sizing degree of 5 to 100 seconds, and that the surface tension of the ink is in the range of-20 to 60 dyn/cm at 20°C.
• an ink-jet recording method in which a recording is made by jetting ink onto a recording medium, characterised in that the recording medium comprises a base paper and an ink acceptor coated on the base paper, the base paper having a basis weight of 50 to 90 g/m 2 and a sizing degree of 5 to 100 seconds, and that the viscosity of the ink is 25 cp or less at 25°C.
• the main feature of the present invention consists in the recording medium having specific structure. Important preferred features lie in the use of inks appropriate to said recording medium.
• the preferred recording medium featuring first the present invention is described below in detail.
• the recording medium can be obtained by providing an ink acceptor on a base paper, in the other words, applying an aqueous coating composition comprising a known filler such as an extender pigment or inorganic pigment, a water-soluble binder such as polyvinyl alcohol, cellulose derivative, polyacrylamide, or starch, and/or an aqueous emulsion (if necessary, a fluorescent whitening agent, dispersant, defoaming agent, surfactant and the like are added) on the base paper of specific properties.
• a fluorescent whitening agent, dispersant, defoaming agent, surfactant and the like are added
• a neutral paper sized in a neutral state is favorably used. That is, according to detailed studies made by the present inventors, ink-jet recording on recording media produced by using prior art papers as base materials of the media raises occasionally various problems such as defective coloration of inks or discoloration or fading of images after recording; further studies made by the present inventors, for the purpose of solving these problems have revealed that almost all the papers hitherto widely used as the base materials have been sheeted under acidic conditions, these acidic papers contain large amounts of acidic components, particularly aluminum sulfate, this aluminum sulfate and other components migrate into ink-receiving layers formed on the papers or adversely affect the ink-receiving layers, changing the layers in quality, and the aluminum sulfate causes defective coloration of dyes contained in inks and discoloration or fading of the dyes after recording.
• the neutral paper preferably used in the present invention is a paper produced by sheeting in a neutral state using not aluminum sulfate, which is used in the prior art, but such an paper-making auxiliary as an alky- lketene dimer, and is noticed in that, even after preservation over a long period (several decades to several hundred years), strength of the papers does not vary differing from the acidic paper hitherto generally used.
• the base paper used for the recording medium in the invention has a basis weight of 50 to 90 g/m 2 .
• the basis weight of the paper is less than 50 g/m 2 , a large portion of the aqueous coating material applied will penetrate the paper and this will tend to develop uneven coating thickness after drying.
• the basis weight is heavier than 90 g/m 2 , the paper may be too thick, inferior in feel and undesirable with respect to the recording workability of the resulting recording medium. Measurement of the basis weight of paper is possible in accordance with JIS P 8110 and P 8111, and also in the present invention, was made in accordance therewith.
• the base paper used in the invention needs to have a sizing degree of 5 to 100 seconds.
• the sizing degree is a value indicating the resistance of paper to wetting with a liquid. Based on this value, it is possible to know the degree of the permeation of an aqueous coating material to the paper .
• the sizing degree is less than 5 seconds even the binder contained in the applied coating material will diffuse into the paper and the paper will swell, resulting in waviness, i.e. minute projections and depressions, on the recording surface.
• the sizing degree exceeds 100 seconds, the applied coating material will scarcely permeate the paper and be repelled by the paper surface, failing in perfect covering of the paper or causing curling of the recording medium on drying.
• the above sizing degree was measured in accordance with JIS P 8122.
• the present inventors have found that papers of basis weights ranging from 50 to 90 g/m 2 and of sizing degrees ranging from 5 to 100 seconds are appropriate as supports for the recording media used in the present invention.
• the thickness of the base paper is desired to be in the range of 60 to 100 ⁇ m. When the paper thickness is less than 60 pm, the paper will result in inconvenient handling because of limpness of itself. When the thickness exceeds 100 ⁇ m, the recording medium will.be felt to be bulky, that is, the preferable feel thereof as a recording medium will be impaired.
• the recording medium favourably used in the present invention is obtained by using such a specific base paper as described above and coating the base paper with a known aqueous coating material by a known method.
• the ink preferably used in the method of the present invention is composed basically of a recording agent, i.e. a colourant such as a dye, and a liquid medium.
• a recording agent i.e. a colourant such as a dye
• Suitable liquid media for the ink include mixtures of water with various organic solvents.
• the water content of the ink used is preferably adjusted to be from 10 to 90 %, more preferably 30 to 70 %, by weight.
• the affinity of the ink to the surface of the recording medium may prove insufficient even for the recording surface of the above described recording medium, in which case the absorbability of the ink will be low, the ink fixing time will be prolonged, the recording speed will be restricted, and additionally with ink droplets overlap at the recording surface, inks dissimilar in colour will mix together and unnecessary spread of ink dots or disorder thereof will occur. Moreover such an ink tends to involve problems in discharge stability and solution stability of the recording agent.
• the water content of the ink is less than 10 % by weight, the coloration, spread, and shape of ink dots may prove insufficient even on the recording surface of the above described recording medium.
• liquid physical properties viscosity, surface tension, etc.
• the rate of ink absorption decreases nearly in inverse proportion to the ink viscosity and thereby the ink dot diameter tends to become smaller.
• Such degrees of changes in recording characteristics vary with the structure and quality of the recording medium.
• liquid physical properties of the ink need to be matched to the recording medium.
• Liquid medium components of the inks used in the method of the present invention may include not only water alone but preferably mixtures of water with various water-miscible organic solvents.
• the viscosity of the resulting ink preferably exceeds 25 cp, more preferably 15 cp, particularly preferably 12 cp.
• the ink viscosity at 25 °C exceeds 25 cp, the ink absorbability of even the above described specific recording medium will be low and therefore the ink fixing time will be prolonged and the recording speed will be restricted, and additionally when ink droplets overlap each other at the recording surface, inks dissimilar in colour will tend to mix together and unnecessary spread of ink dots or disorder thereof may occur, which is undesirable.
• the ink used in the method of the present invention preferably has a surface tension from 20 to 60 dyn/cm, more preferably 35 to 55 dyn/cm, particularly preferably 40 to 50 dyn/cm, at 20°C.
• the spread of ink dots may be too large though the wettability of the recording medium will be high.
• the wettability of the recording medium will be reduced and as a result the absorbability of the ink and the optical density of ink dots will be reduced.
• Liquid medium components of the ink used in the method of the present invention may include not only water alone but preferably mixtures of water with various water-miscible orgnaic solvents.
• Water-miscible organic solvents suitable for use in the preparation of such inks as stated above include; C 1 - c 4 alkyl alcohols, e.g. methanol, ethanol, n-propanol, isopropanol, n-butanol, see-butanol, tert-butanol and isobutanol; amindes, e.g. dimethylformamide and dimethu- lacetamide; ketones or ketone alcohols, e.g. acetone and diacetone alcohol; ethers, e.g. tetrahydrofurane and dioxane; nitrogent-containing heterocyclic ktones, e.g.
• polyalkylene glycols e.g. polyethylene glycol and polypropylene glycol
• alkylene glycols e.g. having 2 to 6 carbon atoms in the alkylene group, e.g. ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, and diethylene glycol
• glycerol lower alkyl ethers of polyhydric alcohols, e.g. ethylene glycol methyl ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or monoethyl) ether.
• diethylene glycol which is a polyhydric alcohol
• triethylene glycol monomethyl (or monoethyl) ether which is a lower alkyl ether of polyhydric alcohol.
• Polyhydric alcohols are particularly favorable because of the great effect thereof as wetting agents for preventing the clogging of the nozzle with the recording agent precipitated on evaporation of water from the ink.
• a solubilization agent may be added to the ink.
• the solubilization agents are nitrogen-containing heterocyclic ketones and the expected action thereof it to improve markedly the solubility of the recording agent in the solvent.
• N-methyl-2-pyrrolidone and 1,3-dimethyl-2-imidazolidinone are favorably used.
• Inks per se prepared from such components as described above are superior in recording characteristics (signal responsiveness, stability for producing droplets, discharge stability, continuous recording workability for many hours, and discharge stability after a long rest), storage stability, and also in such characteristics on the above specified recording medium as dot density, dot shape, degree of spread, clearness of color, ink absorbability, and ink fixability.
• various additives may be incorporated into the inks for the purpose of further improving these characteristics. These additives include; viscosity modifiers, e.g. polyvinyl alcohol, cellulosic resins, and other water-soluble resins; various surfactants of cationic, anionic, and nonionic types; surface tension modifiers, e.g. diethanolamine and triethanolamine; and pH conditioners such as buffers.
• an inorganic salt such as lithium chloride, ammonium chloride, or sodium chloride is used as a resistivity modifier.
• Urea or thiourea is favorably used for improving the water-holding ability of the ink at a head of a discharge orifice.
• thermal properties e.g. specific heat, coefficient of thermal expansion, and heat conductivity
• the ink-jet recording method of the present invention employing the above specified ink and recording medium may be applied on the basis of any technique that is capable of discharging the ink effectively through nozzles and making it adhere to the above specified recording medium that is the target. Representatives of such techniques are detailed, for example, in IEEE Transactions on Industry Applications, Vol, IA-13, No. 1 (Feb. and Mar. 1977), "Nikkei Electronics” issued April 19, 1976, January 29, 1973 and May 6, 1974.
• the first is the electrostatic attraction technique, which comprises (1) applying a strong electric field between a nozzle and an accelerating electrode placed apart from several milli meters in front of the nozzle to withdraw ink particles successively through the nozzle and applying information signals to deflecting electrodes when the ink particles fly between these electrodes or (2) jetting ink particles in response to information signals without deflecting the path of each particle, thereby recording information.
• the second is the supersonic vibration technique, which comprises applying high pressure with a small pump to the ink vibrating the nozzle mechanically by means of e.g. a quartz oscillator to jet fine ink particles forcibly, giving electric charge at the same time to jetted ink particles in response to information signals, and deflecting the path of each ink particles passing between deflecting electrode plates, in response to amount of the charge given to the particles.
• a quartz oscillator to jet fine ink particles forcibly, giving electric charge at the same time to jetted ink particles in response to information signals, and deflecting the path of each ink particles passing between deflecting electrode plates, in response to amount of the charge given to the particles.
• micro-dot ink-jet technique which comprises discharging two groups of ink droplets different in size through a nozzle by keeping the ink pressure and vibration conditions within respective proper ranges, and utilizing the smaller ink droplets alone for recording.
• This technique is characterized in that fine ink droplets can be produced even by using a usual large diameter nozzle.
• the third is the piezoelectric device technique, which, unlike the other techniques, utilises not any mechanical means such as a pump but a piezoelectric device.
• This technique comprises jetting ink droplets through a nozzle by applying electric signal to the piezoelectric device to cause mechanical displacement to pressurize the ink. Any of the above various ink-jet recording techniques can be used in the present invention.
• the recording medium above described preferably in conjunction with inks as described to obtain good recording results, as will be shown in the following examples, such that the optical density of ink dots is uniform throughout the recording surface, shapes of almost all the ink dots are circles of similar sizes without distortion, and the spread of ink dots is appropriate. Accordingly, the invention permits very distinct, high quality images to be obtained, free of unevenness throughout the recording surface. In addition, the recording medium shows no curling after recording as well and has a good feel.
• a coating composition was prepared by using precipitated calcium carbonate (average particle size 1 ⁇ m) as a filler and poly (vinyl alcohol) and an SBR latex as binders according to the following recipe:
• This coating composition was applied on a wood-free paper, as a base paper of 52 g/m 2 in basis weight, 12 seconds in sizing degree, and 65 ⁇ m in thickenss by means of a blade coater to give a coating thickenss of 2 pm, and was dried in the ordinary way.
• the thus obtained recording medium was free of the unevenness of coating thickness and the curling.
• Ink-jet recording on this recording medium was performed by using the following six kinds of inks and a recorder provided with an on-demand type of ink-jet recording head (discharge orifice diameter 65 pm, piezoelectric oscillator driving voltage 70 V, its frequency 3 KHz) for discharging ink droplets therefrom by means of the piezoelectric oscillator, and recording characteristics of the recording medium were evaluated. Thus, extremely distinct images free of recording irregularity were obtained. The recording medium did not curl after recording and was good in feel as a paper.
• Example la Using each sample medium shown in Table 2a, the recording procedure of Example la was followed (ink No. Ba was used). After recording, the irregularity in dot diameters was determined on each sample. Results thereof are shown in Table 2a.
• a coating composition was prepared by using a silica powder (tradename: Nipsil E 220 A, supplied by Nippon Silica Kogyo Co., Ltd., average particle size 1.0 pm) as a filler according to the following recipe:
• a coating composition was prepared by using precipitated calcium carbonate (average particle size 1 pm) as a filler and polyvinyl alcohol and an SBR latex as binders according to the following recipe:
• This coating composition was applied on a wood-free base paper of 52 g/m 2 in basis weight, 12 seconds in sizing degree and 65 ⁇ m in thickness by means of a blade coater to give a coating thickness of 2 pm, and was dried in the ordinary way.
• the thus obtained recording medium was free of the unevenness of coating thickness and the curling.
• Ink-jet recording on this recording medium was performed by using the following 6 kinds of inks and a recorder provided with an on-demand type of ink-jet recording head (discharge orifice diameter 65 pm, piezoelectric oscillator driving voltage 70 V, its frequency 3 KHz) for discharging ink droplets therefrom by means of the piezoelectric oscillator, and recording characteristics of this recording medium were evaluated. Thus, extremely distinct images free of recording unevenness were obtained. The recording medium did not curl on recording and was good in feel as paper.
• Example lb Using each sample medium shown in Table 2b, the recording procedure of Example lb was repeated (ink No. Cb was used). After recording, the irregularity in dot diameters was determined on each sample. Results thereof are shown in Table 2b.
• a coating composition was prepared by using a silica powder (tradename: Nipsil E 220 A, supplied by Nippon Silica Kogyo Co., Ltd., average particle size 1.0 ⁇ m) as a filler according to the following recipe:
• Example 3b Various grodes of base papers, as shown in Table 4, different in basis weight and definite in sizing degree (12 seconds) and in thickness (70 pm and 85 pm) were coated similarly to Example 3b with a portion of the coating composition prepared in Example 3b, thus preparing recording media.
• a coating composition was prepared by using precipitated calcium carbonate (average particle size 1 ⁇ m) as a filler and poly (vinyl alcohol) and an SBR latex as binders according to the following recipe:
• This coating composition was applied on a wood-free base paper of 52 g/m 2 in basis weight, 12 seconds in sizing degree, and 65 pm in thickness by means of a blade coater to give a coating thickness of 2 pm, and was dried in the ordinary way.
• the thus obtained recording medium was free of the unevenness of coating thickness and the curling.
• Ink-jet recording on this recording medium was performed by using the following 6 kinds of inks and a recorder provided with an on-demand type of ink-jet recording head (discharge orifice diameter 65 ⁇ m, piezoelectric oscillator driving voltage voltage 70 V, its frequency 3 KHz) for discharging ink droplets therefrom by means of the piezoelectric oscillator, and recording characteristics of this recording medium were evaluated. Thus, extremely distinct images free of recording unevenness were obtained. The recording medium did not curl after recording and was good in feel as paper.
• Example lc Using each sample medium shown in Table 2c, the recording procedure of Example lc was followed (ink No.Cc was used). After recording, the irregularity in dot diameters was determined on each sample. Results thereof are shown in Table 2c.
• a coating composition was prepared by using a silica powder (tradename: Nipsil E220A, supplied by Nippon Silica Kogyo Co., Ltd., average particle size 1.0 pm) as a filler according to the following recipe:
• this coating composition was applied on a wood-free base paper of 60g/m 2 in basis weight, 20 seocnds in sizing degree, and 73 ⁇ m in thickness by means of a blade coater to give a coating thickness of 2 ⁇ m, and was dried in the ordinary way, giving recording medium.
• the un--evenness of coating thickness or the coat-lacking site was not observed at all and the curling did not result.
• Recording on this recording medium in a similar way as in Example 1c gave extremely distinct images free of recording irregularity. This recording medium did not curl on recording and was good in feel as paper. Results of evaluating recording characteristics are shown in Table 3c.
• Example 4c Various grades of base paper, as shown in Table 4c, different in basis weight and definite in sizing degree (12 seconds) and in thickness (70 pm and 85 pm) were coated similarly to Example 3c with a portion of the coating composition prepared in Example 3c, thus preparing recording media.
• the ink-jet recording and the evaluation of the ink recording characteristics of the recording medium were repeated similarly to Examples la to 4a except for using a neutral paper of 90 g/m in basis weight and 0 seconds in sizing degree being prepared as base paper by mixing a hard wood bleached kraft pulp and a soft wood bleached kraft pulp, as raw material pulps, in a weight ratio of 1 : 1, and beating the mixture in a refiner to a freeness of 100 ml, followed by sheeting, in place of the papers used in Examples la to 4a. Similar results to Examples la to 4a were obtained.
• Example lb to 4b The ink-jet recording and the evaluation of the ink recording characteristics of the recording medium were repeated similarly to Examples lb to 4b except for using a neutral paper of 50g/m 2 in basis weight and 30 seconds in sizing degree being prepared as base paper in the same manner as in Example ld but using an alkyl- ketene dimer (Size Pine K-902, supplied by Arakawa Chemical Co., Ltd.) in the sheeting process as an auxiliary for preparing neutral paper. Similar results to Examples lb to 4b were obtained.

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• 1985
  • 1985-09-12 EP EP85306499A patent/EP0174859A3/fr not_active Withdrawn

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