Stock material or miscellaneous articles – Composite – Of polyamidoester
Reexamination Certificate
2000-03-22
2001-10-16
Chen, Vivian (Department: 1773)
Stock material or miscellaneous articles
Composite
Of polyamidoester
C428S480000, C428S483000, C428S690000, C428S910000, C528S308000, C427S372200, C427S384000, C427S385500, C427S393500
Reexamination Certificate
active
06303228
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a thermal transfer ribbon and to a base film thereof. More specifically, it relates to a thermal transfer ribbon for use as a transfer material for a thermal transfer printer, which has excellent printing performance without blurred ink at the time of high-speed printing and without wrinkles formed by friction with a head and to a base film thereof.
BACKGROUND ART
As a base film for a thermal transfer ribbon for use in a thermal transfer printer, one having a specific surface roughness (JP-A 62-299389) is known.
Of thermal transfer recording materials, demand for a sublimation-type transfer recording system has been sharply growing because the recording system is capable of outputting a high-quality full-color image with ease. The sublimation-type thermal transfer is a system in which only a thermally sublimating dye contained in a binder sublimes by heat and is absorbed into the image receiving layer of paper to which an image is transferred to form a gradation image. Since the temperature of a thermal head at the time of printing has become higher along with recent demand for higher printing speed, the quantity of heat received by a thermal transfer printer ribbon has increased. Therefore, the deformation of a film used as a base film of the ribbon has become larger, whereby an unclear printed image is produced or wrinkles are produced in a ribbon at the time of printing, or in an extreme case, printing is utterly impossible. Therefore, the improvement of printing performance has been desired.
Further, in sublimation-type thermal transfer, only a thermally sublimating dye contained in a binder sublimes by heat and is absorbed into the image receiving layer of paper to which an image is transferred to form a gradation image. In order to sublimate only the dye, high adhesion is required between the binder and the base film and, further, the adhesion must not be reduced by environmental changes and the passage of time. When the adhesion is not sufficient, the binder layer transfers to the paper and greatly impairs gradation, thereby causing an “over-transfer” phenomenon. Since a polyester film generally has highly oriented crystals, the film has such poor adhesion that an ink layer is not adhered to the polyester film at all even when it is formed on the film directly. Therefore, to improve the adhesion of the polyester film to the ink layer, a physical or chemical treatment is given to the surface of the film. However, sufficient adhesion still cannot be obtained even by the treatment.
When the ribbon is separated from an image-received sheet after printing, the ink layer may be taken away by the image-received sheet due to the delamination of the surface of the base film, which may cause abnormal transfer. Therefore, the improvement with regard to this has been desired.
DISCLOSURE OF THE INVENTION
It is an object of the present invention to provide a base film for a thermal transfer ribbon which has excellent printing performance without blurred ink at the time of high-speed printing and without wrinkles formed by friction with a head.
It is another object of the present invention to provide a base film for a thermal transfer ribbon, which is not heavily deformed at the time of heating, has excellent adhesion to a thermal transfer ink layer and can give a transferred image having excellent gradation.
It is still another object of the present invention to provide a thermal transfer ribbon comprising the above base film of the present invention as a base film and having the above excellent characteristic properties.
Other objects and advantages of the present invention will become apparent from the following description.
According to the present invention, firstly, the above objects and advantages of the present invention are attained by a base film for a thermal transfer ribbon, which is a biaxially oriented polyester film comprising polyethylene-2,6-naphthalene dicarboxylate as a main constitutional element, wherein in a temperature-dimensional change curve under load in the longitudinal direction of the film, the dimensional change from the original length of the film at temperatures of up to 200° C. is 1.0% or less and the dimensional change from the original length of the film at temperatures of up to 230° C. is 3.0% or less.
According to the present invention, secondly, the above objects and advantages of the present invention are attained by a thermal transfer ribbon comprising the above base film of the present invention and a sublimation-type thermal transfer ink layer formed on the base film.
PREFERRED EMBODIMENT OF THE INVENTION
The present invention will be described in detail hereunder.
Polyethylene-2.6-naphthalene Dicarboxylate
The thermal transfer ribbon of the present invention comprises polyethylene-2,6-naphthalene dicarboxylate as a main constitutional element. This polyethylene-2,6-naphthalene dicarboxylate is preferably a homopolymer whose recurring units are all ethylene-2,6-naphthalene dicarboxylate or a copolymer comprising ethylene-2,6-naphthalene dicarboxylate in an amount of at least 80 mol % of the total of all the recurring units. When the ethylene-2,6-naphthalene dicarboxylate is contained in an amount of 80 mol % or more of the total of all the recurring units, a film which undergoes only a small dimensional change at high temperatures can be obtained without impairing the characteristic properties of polyethylene-2,6-naphthalene dicarboxylate heavily.
A preferred copolymer component is a compound having two ester-forming functional groups in the molecule, as exemplified by dicarboxylic acids such as oxalic acid, adipic acid, phthalic acid, sebacic acid, dodecanedicarboxylic acid, succinic acid, isophthalic acid, 5-sodium sulfoisophthalic acid, terephthalic acid, 2-potassium sulfoterephthalic acid, 2,7-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, phenylindanedicarboxylic acid and diphenyl ether dicarboxylic acid, and lower alkyl esters thereof; oxycarboxylic acids such as p-oxyethoxybenzoic acid, and lower alkyl esters thereof; and glycols such as propylene glycol, 1,2-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, p-xylylene glycol, adduct of bisphenol A with ethylene oxide, triethylene glycol, polyethylene oxide glycol, polytetramethylene oxide glycol and neopentyl glycol.
The polyethylene-2,6-naphthalene dicarboxylate may have some or all of its terminal hydroxyl groups and/or carboxyl groups capped with a monofunctional compound such as benzoic acid or methoxypolyalkylene glycol, or it may be modified by such a trace amount of a polyfunctional ester-forming compound having 3 or more functional groups such as glycerin or pentaerythritol that a substantially linear polymer can be obtained.
Additives
The polyethylene-2,6-naphthalene dicarboxylate base film of the present invention may contain such additives as a stabilizer, dye, lubricant, ultraviolet absorber and flame retardant as desired.
To provide preferable slipperiness for the film, it is preferable that the film contain a small amount of inert fine particles. Illustrative examples of the inert fine particles include inorganic particles such as spherical silica, porous silica, calcium carbonate, silica alumina, alumina, titanium dioxide, kaolin clay, barium sulfate and zeolite; and organic particles such as silicone resin particles and crosslinked polystyrene particles. Synthetic inorganic particles are preferred to natural ones because they are uniform in size, and inorganic particles of any crystal form, hardness, specific gravity and color may be used.
The average particle diameter of the above inert fine particles is preferably in the range of 0.05 to 5.0 &mgr;m, more preferably 0.1 to 3.0 &mgr;m.
The content of the inert fine particles is preferably 0.001 to 1.0 wt %, more preferably 0.03 to 0.5 wt %.
The inert fine particles to be added to the film may consist of a sing
Harada Nobuyuki
Suzuki Kenji
Watanabe Shinya
Yano Shinji
Chen Vivian
Sughrue Mion Zinn Macpeak & Seas, PLLC
Teijin Limited
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