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
  • B41M5/52—Macromolecular coatings
  • B41M5/5254—Macromolecular coatings characterised by the use of polymers obtained by reactions only involving carbon-to-carbon unsaturated bonds, e.g. vinyl polymers

Definitions

• This invention relates to a recording medium to be used preferably for ink jet recording method, particularly to a recording medium excellent in ink receptivity and giving sharpness and water resistance of the recorded image.
• Ink jet recording method performs recording by generating small droplets of ink according to various ink - (recording liquid) discharging systems, such as an electrostatic attraction system, a system of giving mechanical vibration or displacement to ink by use of a piezoelectric element, a system utilizing pressure of bubbles formed by heating ink and permitting ink droplets to fly and attach a part or whole thereof onto a recording medium such as paper.
• This method is now attracting attention as a recording method which generates less noise and is capable of performing high speed printing and multi-color printing.
• inks For ink jet recording, inks have been used which is composed mainly of water in view of safety and recording characteristics. In most cases, a polyhydric alcohol is added to inks for the purpose of prevention of clogging of nozzles and improvement of discharging stability.
• recording media to be used for the ink jet recording method there have been employed recording media comprising a porous ink receiving layer provided on an ordinary paper or a substrate called as the ink jet recording paper.
• the recording medium for ink jet recording for obtaining recorded images of high resolution and high quality needs to satisfy various basic requirements as follows:
• Uses of the recording medium other than for surface image observation may include those in which recorded images are projected onto a screen, etc. by means of an optical instrument such as a slide or an OHP (overhead projector), etc. and those in which images are observed by means of color resolution plates during preparation of a positive plate for color printing, and a CMF (a color mosaic filter), etc. to be used for color display such as liquid crystal, etc.
• the transmitted light through the recorded images becomes a problem in the recording medium in these uses, which is different from the uses for surface image observation where diffused light mainly from a recorded image is observed. Accordingly, light transmissivity, particularly excellent linear transmittance is required in addition to the requisite performances in general of the recording medium for ink jet recording.
• a non-volatile component such as polyhydric alcohol, etc. in the ink will remain even after recording on the surface of the recording medium for a long time, whereby drying for fixing ink is prolonged, this involving the drawbacks such that ctothings may be soiled by contact with the recorded images or that the recorded images may be damaged.
• the surface of the ink receiving layer becomes sticky under highly humid conditions, whereby the problems arises such that it is adhered onto the delivery roller when mounted on a printer, thus failing to be conveyed, and also that the recording medium will be subject to blocking when placed one upon another.
• an object of the present invention is to provide a recording medium for use in ink jet recording which is particularly excellent in ink receptivity and giving water resistance and sharpness of recorded image.
• Another object of the present invention is to provide a recording medium for use in full color ink jet recording which is excellent in ink receptivity, and giving sharpness of recorded image and surface gloss, and also free from stickiness of the surface, blocking, etc. even under highly humid conditions.
• Still another object of the present invention is to provide a recording medium for use in ink jet recording, which can be used for observation by projection of recorded image by means of an optical instrument such as a slide or an OHP, or which can be used for observation of transmit-1ed light such as a color resolution plate during preparation of a positive plate for color printing or a CMF, etc. to be used for color display such as liquid crystal.
• an optical instrument such as a slide or an OHP
• transmit-1ed light such as a color resolution plate during preparation of a positive plate for color printing or a CMF, etc.
• a recording medium which comprises having an ink receiving layer containing a polymer complex of a basic polymer and an acidic polymer.
• a recording method which performs recording by forming liquid droplets of a recording liquid and permitting the liquid droplets to be attached on the surface of a recording medium, wherein the recording liquid is an aqueous ink and the surface of the recording medium contains a polymer complex of a basic polymer and an acidic polymer.
• the recording medium of the present invention is characterized principally in that its ink receiving layer comprises a polymer complex of a basic polymer and an acidic polymer and the objects of the present invention can be accomplished primarily by such a characteristic.
• the recording medium of the present invention generally comprises a substrate as the supporting material and a recording surface, namely an ink receiving layer, provided on its surface.
• a substrate as the supporting material
• a recording surface namely an ink receiving layer, provided on its surface.
• particularly preferred embodiments may include the following:
• the ink receiving layer may also serve as a support.
• the polymer complex which characterizes principally the present invention comprises a basic polymer and an acidic polymer.
• polymer complexes comprising a basic polymer and an acidic polymer are known as disclosed in, for example, Japanese Patent Publication Nos. 37017/1976 and 42744/1980.
• preferable basic polymers may include, for example, those as set forth below:
• copolymerizable monomers to be used for the above copolymers may include methacrylate, acrylate, acrylamide, acrylonitrile, vinyl ether, vinyl acetate, vinylimidazole, ethylene, styrene and other monomers in general.
• Particularly useful in the present invention are homopolymers and copolymers of N-vinylpyrrolidone, N-vinylpiperidone, N-vinylcaprolactam, N-vinylmorpholine, N-vinyl-2-oxazolidone, N-viryl-5-methyl-2-oxazolidone, etc.
• the nitrogen-containing monomer as described above in the copolymers is preferably contained in an amount of 50 mole % or more.
• the acidic polymer capable of forming a polymer complex with the above basic polymer may include, for example, polymers shown below.
• the "acidic polymer" in the present invention is also inclusive of those having alcoholic hydroxyl groups, other than those having suffonic acid groups, carboxylic acid groups, sulfuric acid ester groups, phosphoric acid ester groups, or phenolic hydroxyl groups in its molecule.
• Carboxyl terminated polyesters obtained by the reaction of polycarboxylic acids such as citric acid, tartaric acid, phthalic acid with polyhydric alcohols such as ethylene glycol, 1,4-butane diol, diethylene glycol, etc. in the presence of acids in excess.
• polycarboxylic acids such as citric acid, tartaric acid, phthalic acid
• polyhydric alcohols such as ethylene glycol, 1,4-butane diol, diethylene glycol, etc. in the presence of acids in excess.
• Acidic cellulose derivatives modified with various kinds of polycarboxylic acids see Japanese Patent Publication No. 5093/1960;
• Cellulose derivatives such as O-ethylcellulose acetate hydrogen sulfate hydrogen phthalate, cellulose acetate hydrogen sulfate hydrogen phthalate, ethylcellulose hydrogen-O-sulfobenzoate, O-P-sulfonbenzylcellulose acetate, 0-ethyl-O-P-sulfoethylcellulose acetate, etc. (see Japanese Patent Publication No. 5093/1960);
• Sulfonic acid-modified polymers of polyvinyl alcohol or vinyl alcohol copolymer with sulfonic acid compounds e.g. O-sulfobenzoic acid, sulfopropionic acid, sulfovaleric acid, sulfobenzaldehyde, sulfophthalic acid, etc.
• sulfonic acid compounds e.g. O-sulfobenzoic acid, sulfopropionic acid, sulfovaleric acid, sulfobenzaldehyde, sulfophthalic acid, etc.
• phenolic acidic polymers there may be included specifically those having phenolic hydroxyl groups in their main chains and/or side chains.
• Such phenolic acidic polymers may include so-called phenol resins or initial condensates thereof obtained by addition-condensation reaction of monomers of phenols having hydroxyl groups in the aromatic ring such as phenol, m-cresol, 3,5-xylenol, p-alkylphenol, resorcin, a- or ⁇ -naphthol, etc. or derivatives thereof with an aldehyde such as formalin.
• These polymers may be either homopolymers or copolymers, which may be either random, block or graft copolymers.
• Such phenolic acidic polymers may have various molecular weights from relatively lower molecular weights which are soluble in water or organic solvents to those with higher molecular weights which are insoluble and unmel- table.
• those soluble in water, organic solvents such as alcohol, ketone, etc., for example, initial condensates of phenol resins are particularly useful.
• phenolic acidic polymers are generally hydrophilic, but they are hard and can form only brittle coated films, and therefore are not applicable at all for the ink receiving layer of a recording medium.
• ink receiving layers having various excellent performances can be formed.
• polymers or copolymers with other monomers in general of vinyl monomers having phenolic hydroxyl groups such as vinylphenol vinylnaphthol, etc.
• Any of the acidic polymers as described above can preferably be used:
• the present inventors have further investigated comprehensively uses of these polymer complexes, and found that these polymer complexes, although they are markedly hydrophilic, are resistant to water and humidity and exhibit ink receptivity comparable to that of water-soluble polymers of the prior art to give sharp images, and yet their surfaces will not become sticky even under highly humid conditions. Further, it has also been found that, when a phenolic polymer is used as the acidic polymer, the strength at the portion which has received ink becomes more strong, and the film will not easily be peeled off nor broken even when touched with a finger or a thing.
• the polymer complex of the present invention may be isolated by dissolving each of the starting polymers in a poor solvent respectively and then mixing both solutions.
• a solution of a polymer complex can be obtained by dissolving the starting polymers in a relatively good solvent such as dimethylfomamide, dimethylacetamide, dimethylsulfoxide, etc.
• Preferable basic polymers and acidic polymers for formation of a polymer complex as described above may be those having respective molecular weights of 500 or more, preferably 1,000 or more, and an ink receiving layer with great strength excellent in ink receptivity giving sharpness of the image, water resistance and ink resistance can be formed from both types of polymers of such molecular weights.
• the proportion of both polymers to be employed may be within the range of 20/1 to 1/10 in terms of weight ratio of basic polymer to acidic polymer, preferably a ratio at which the basicity and the acidity of the respective polymers are approximately equal. Outside the range of the above weight ratio, bonding between both polymers will be insufficient, whereby the objects of the present invention cannot fully be achieved. For example, With a large excess of the basic polymer, water resistance will be reduced, while with a large excess of the acidic polymer, ink receptivity will be reduced.
• a condensation product of D-sorbitol and benzaldehyde may be added to the above polymer complex at a proportion of 0.1 to 50 % by weight
• the ink receiving layer of the recording medium of the present invention can be formed by use of the polymer complex as described above, but it is also possible in the present invention to use additionally other polymers than the polymer complex as described above, for example, other light transmissive polymers in combination with the above polymer complex.
• Preferred as such other polymers are natural resins such as albumin, gelatin, casein, starch, cationic starch, gum arabic, sodium alginate, etc.; and synthetic resins such as polyvinyl alcohol, polyamide, polyacrylamide, quatemariz- ed polyvinyl pyrrolidone, polyethyleneimine, polyvirnyl- pyridinium halide, melamine resin, polyurethane, polyester, sodium polyacrylate, etc. At least one of these materials may be used in combination, if desired.
• resins such as SBR tatex, NBR latex, polyvinylformal, polymethyl methacrylate, polyvinylbutyral, polyacrylonitrile, polyvinyl chloride, polyvinyl acetate, phenol resin, alkyd resin may also be used in combination, if necessary.
• ink absorptivity of the ink receiving layer it is possible to disperse fillers such as silica, clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, aluminum silicate, synthetic zeolite, alumina, zinc oxide, lithopon, satin white, etc. in the ink receiving layer.
• fillers such as silica, clay, talc, diatomaceous earth, calcium carbonate, calcium sulfate, barium sulfate, aluminum silicate, synthetic zeolite, alumina, zinc oxide, lithopon, satin white, etc.
• the substrate to be used as the supporting material for the ink receiving layer in the present invention may be any substrate known in the art, transparent or opaque.
• transparent substrates may include films or plates such as of polyester resins, diacetate resins, polycarbonate resins, polyvinyl chloride resins, polyimide resins, cellophane, celluloid, etc. and glass plates.
• Preferable opaque substrates may include, for example, paper, cloth, wood, metal plate, synthetic paper in general, or otherwise the above transparent substrates which have been made opaque according to known means.
• the recording medium of the present invention is formed by use of the main materials as described above.
• both of the substrate and the ink receiving layer are light transmissive, with the linear transmittance being 10 % or higher, and it is an embodiment in which the recording medium as a whole is light transmissive.
• the recording medium of this embodiment is particularly excellent in light transmissivity and employed primarily in the uses such as an OHP, etc. in which recorded image is projected onto a screen, etc. by means of an optical instrument, thus being useful for observation with transmitted light
• Such a light transmissive recording medium can be prepared by forming a light transmissive ink receiving layer from a polymer complex as described above alone or a mixture of this polymer complex with another light transmissive polymer on the light transmissive substrate as described above.
• a coating solution is prepared by dissolving or dispersing the above polymer complex or a mixture with another appropriate polymer and said solution is coated on the light transmissive substrate according to the known method such as roll coating, rod bar coating, spray coating, air knife coating, etc., followed by rapid drying, or a method in which one solution of either the basic polymer or the acidic polymer is applied and then the other solution to form a polymer complex on the substrate.
• the recording medium according to the embodiment - (1) formed as described above is a light transmissive recording medium having sufficient light transmissivity.
• the sufficient light transmissivity as herein mentioned means that the linear transmittance of the recording medium should desirably exhibit at least 2 %, preferably 10 % or higher.
• the recorded image can be observed by projection by, for example, an OHP onto a screen. Further, in order for the fine portion of the recorded image to be observed sharply, the linear transrrittance should desirably be 1 0 % or higher.
• the linear transmittance T (%) as herein mentioned is a value which is determined by measuring the spectral transmittance of the linear light which enters a sample perpendicularly, transmits through the sample, passes through a slit on the light receiving side which is located at least 8 cm apart form the sample on the line extended from the incident light pathway and is received on a detector, by means of, for example, 323 Model Hitach Automatic Recording Spectrophotometer (produced by Hitachi, Ltd.), further determining the Y value of tristimulus values of color and calculating from the following formula:
• the linear transmittance as mentioned in the present invention is relative to linear light, and it is different from diffuse transmittance (transmittance is determined so as to be inclusive of diffused light by providing an integrating sphere at the back of a sample) or opacity (determined from the ratio of values when white and black backings are placed on the back of a sample) according to the method in which light transmissivity is evaluated with diffused light
• the non-recorded portion in the projected image is required to be light, namely the linear transmittance of the recording medium should be at a certain level or higher.
• the linear transmittance of the recording medium needs to be 2 % or higher, preferably 10 % or higher in order to obtain a sharper image. Therefore, the recording medium suited for this purpose is required to have a linear transmittance which is at least 2 %.
• the embodiment (2) as mentioned above is also a modification of the above embodiment (1), and it is characterized by that the surface of its ink receiving layer is smooth and has a 45 degree mirror surface gloss of at least 30 % based on JIS Z8741.
• the recording medium of said type is particularly excellent in surface gloss and particularly useful as a recording medium for observation of a surface image which is of full color and excellent in sharpness.
• the recording medium according to this embodiment may be either transparent or opaque, and any of the above transparent and opaque materials can be used.
• the ink receiving layer may be either transparent or opaque.
• the materials and the method to be used for formation of the ink receivng layer may be the same as described above embodiment (1), but the above-mentioned fillers can be used even to the extent such that the ink receiving layer may become' opaque, provided that the surface of the ink receiving layer can retain its smoothness.
• the ink receiving layer to be formed on the substrate may have a thickness of generally 1 to 200 ⁇ m, preferably 3 to 100 ⁇ m, more preferably 5 to 30 ⁇ m.
• organic or inorganic fine powder imparted at a proportion of about 0.01 to about 1.0 g/m 2 on the recording surface of the recording medium of various embodiments as described above will further improve the conveying characteristic within the printer, antiblocking characteristic during piling, fingerprint resistance, etc. of the recording medium obtained.
• the recording medium of the present invention will not of course be limited to these embodiments.
• the ink receiving layer and/or the ink permeable layer may contain various known additives, including dispersing agents, fluorescent dyes, pH controllers, defoaming agents, lubricants, preservatives, surfactants. etc.
• the recording medium of the present invention is not necessarily required to be colorless, but it may also be a colored recording medium.
• the recording medium of the present invention can exhibit excellent ink receptivity similarly as that having an ink receiving layer formed with a water-soluble polymer of the prior art and provide a recorded image of excellent sharpness, with its surface not becomig tacky or sticky.
• the recording medium of the present invention does not become tacky or sticky on the surface of the ink receiving layer, being different from the recording medium using a water-soluble polymer of the prior art, even when recording as described above may be performed under highly humid conditions, there will be caused no trouble in the printer: neither blocking nor color transfer occurs when they are placed one upon another.
• Such excellent effects under highly humid conditions may be considered to be due to formation of a polymer complex through generation of some weak bonding between the molecules of the two kinds of the polymers used for formation of the ink receiving layer such as electrostatic force between ions, hydrogen bonding, Van der Waals force, partial charge transfer, etc., thus exhibiting excellent water resistance even under highly humid conditions, while retaining high ink receptivity.
• the present invention it is also possible to provide a recording medium excellent in surface gloss which has not been found in the recording medium for ink jet recording of the prior art. Further, it can be applied for uses other than surface image observation of the prior art such as for observation by projection of a recorded image by an optical instrument such as a slide, an OHP, etc., a color resolution plate during preparation of a positive plate for color printing, or a CMF, etc. to be used for color display such as liquid crystal, etc.
• An amount of 66 parts of an aqueous 10 % polyvinylpyrrolidone solution (PVPK-90, produced by GAF) was mixed with 34 parts of an aqueous 10 % solution of a methyl vinyl ether/mateic anhydride copolymer (GANTREZ AN-169, produced by GAF).
• the mixture gelled to form a polymer complex
• a polyethylene terephthalate film with a thickness of 100 ⁇ m (produced by Toray) was employed, and a coating solution having the composition shown above was applied onto this substrate film to a thickness after drying of 8 ⁇ m according to the bar coater method, and dried under the conditions of 80 °C and 10 minutes to give a light transmissive recording medium of the present invention.
• the recording medium of the present invention thus obtained was found to be colorless and transparent
• coating solutions were prepared and 4 kinds of light transmissive recording media of the present invention and 3 kinds of comparison recording media were obtained by forming an ink absorbing layer on the same polyethylene terephthalate film as used in Example 1 in the same manner as in Example 1 .
• a polyethylene terephthalate film with a thickness of 100 ⁇ m (produced by Toray) was employed, and a coating solution having the composition shown above was applied onto this substrate film to a thickness after drying of 8 ⁇ m according to the bar coater method, and dried under the conditions of 80 °C and 10 minutes to give a light transmissive recording medium of the present invention.
• the recording medium of the present invention thus obtained was found to be colorless and transparent.
• compositions as shown below By use of the compositions as shown below, coating solutions were prepared and 3 kinds of light transmissive recording media of the present invention and 2 kinds of recording media for comparative purpose were obtained by forming an ink absorbing layer on the same polyethylene terephthalate film as used in Example 9 in the same manner as in Example 9.
• ink jet recording was practiced by use of the four kinds of ink as shown below by means of a recording device having an on-demand type ink jet recording head which discharges ink by a piezoelectric vibrator (discharge orifice diameter: 60 ⁇ m, piezoelectric vibrator driving voltage: 70 V, frequency 2 KHz).

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Ink Jet Recording Methods And Recording Media Thereof (AREA)
• Duplication Or Marking (AREA)
• Ink Jet (AREA)

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Cited By (15)

Citations (5)

• 1986
  • 1986-02-14 EP EP86301024A patent/EP0191645A3/fr not_active Withdrawn

Patent Citations (5)

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