JPH05238172A - Thermal transfer recording image receiving paper - Google Patents

Abstract

PURPOSE:To provide the title image receiving paper excellent in high speed recording properties, generating no transfer irregularity or missing dots, having high contrast, reproducing a natural hue, imparting a sharp color hue, excellent in full-color recording paper aptitude and capable of obtaining a high-grade recording image of high image quality. CONSTITUTION:An image receiving layer is provided on base paper by coating or impregnating the base paper with an aqueous coating solution to obtain thermal transfer recording image receiving paper. In this image receiving paper, Z-axis strength conforming to TAPPIUM-403 is 0.05-0.18 ft.1b and the surface of the image receiving layer measured in a fluorescence-containing state on the basis of the display method prescribed in JIS-Z-8729 simultaneously satisfies the condition of L*>=90 and 1.7(a*-1.5)<2>+0.9(b*+5)<2>+0.6(a*-1.5) (b*+5)<=30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a thermal transfer recording image receiving paper used in a copying machine, a printer, a facsimile or the like utilizing a thermal transfer recording system.

[0002]

2. Description of the Related Art In recent years, with the progress of office automation, copying machines, printers and the like utilizing various recording systems such as electrophotographic systems and thermal transfer recording systems have been widely used. These are also used in, for example, CAD / CAM, etc., depending on their respective uses. In this case, a colored coloring material is used for image formation, but normally, the coloring material is melted, evaporated, sublimated, and transferred onto a recording medium, such as paper or a film sheet, and then the adhesion, adsorption, or dyeing action is performed. A recorded image is obtained.

In this type of recording system, an ink ribbon having a heat-fusible ink layer composed of a coloring material is melted by heat, and the coloring material is transferred to a recording paper to be adhered, adsorbed or dyed. Recently, a hot-melt type thermal transfer recording system for obtaining a recorded image has been attracting attention. As a recording medium using this system, plain paper to coated paper type can be used, and the feature is that the specifications are not selected.

By the way, also in this thermal transfer recording system, as in other recording systems, full-color recording, high-speed recording,
The demand for clear images and high resolution is increasing. For example, in order to perform single-color or multi-color recording with a color thermal transfer printer or the like, a color head such as yellow, magenta, cyan, and black, an ink ribbon containing waxes or resins, and recording paper are combined and applied with a thermal head. A transfer image is formed on the recording paper. In this case, since the inks of the respective colors are overlapped with each other, if plain paper is used as the recording paper, defects such as uneven transfer and dot omission are likely to occur due to the smoothness of the surface of the image receiving layer.

For this reason, many proposals have been made for improving the smoothness of the surface of the image receiving layer. For example, those which specify Beck smoothing (Japanese Patent Laid-Open Nos. 59-133092 and 59-187892),
Those provided with a thermal transfer image-receiving layer containing a specific pigment or binder (JP-A-57-182487, JP-A-59-182787, JP-A-60-11)
No. 489, No. 60-110492, No. 60-192690, No. 61-2172
89, 61-286187, 63-21185) and the like. However, in the case of these conventional methods, although some improvement effects are recognized, transfer unevenness and color misregistration at overlapping portions of color inks in multicolor recording, transfer dot (ink) dropout, dot shape reproducibility failure, etc. The deterioration of the image clarity due to the phenomenon has not been completely solved. Therefore, it is not enough to simply enhance the calendering process to improve smoothness, or to include a specific pigment or adhesive in the thermal transfer image-receiving layer, and it is possible to eliminate the above-mentioned drawbacks and to improve the transferability and dot reproducibility of ink. The reality is that no excellent image-receiving paper for thermal transfer recording has been obtained yet.

Further, with the recent expansion of the field of use of the thermal transfer recording system, and particularly with the spread of color printers, the transferred image in which the inks of respective colors are superposed reproduces a more natural color tone, the color tone is vivid, and the quality is high. The development of recording paper that can obtain high-quality recorded images has attracted attention as an urgent issue.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a transfer image having excellent color reproducibility and image clarity of a thermal transfer recording image receiving paper, and particularly to ink transferability, reproducibility, resolution, gradation and
High-speed, high-quality recording with excellent high-speed recording properties, no transfer unevenness or missing dots, high contrast, more natural color reproduction, and vivid color tones, suitable for full-color recording paper. An image receiving paper for thermal transfer recording on which an image is obtained is provided.

[0008]

The present invention is a thermal transfer recording image-receiving paper having an image-receiving layer formed by coating or impregnating a base paper with an aqueous coating liquid, which is in accordance with TAPPI UM-403 of the image-receiving paper. Axial strength is 0.05-0.18ft ・ lb and the surface of the image receiving layer is JIS-Z-87
An image receiving paper for thermal transfer recording characterized by satisfying the following conditions at the same time when measured in a state of containing fluorescent light based on the display method specified in 29. L * ≧ 90 1.7 (a * -1.5) ² +0.9 (b * + 5) ² +0.6 (a * -1.5) (b * + 5) ≦ 30

[0009]

The present inventors have made earnest studies on a method of solving the above-mentioned problems, capable of reproducing high quality images, and of obtaining high-speed recording as well as thermal transfer recording image-receiving paper excellent in suitability for full-color recording paper. It was As a result, in order to obtain the desired effect, the base paper, which is the main part of the thermal transfer recording image receiving paper, is provided with appropriate voids, cushioning properties, and flexibility, and the adhesiveness between the ink ribbon and the recording image receiving surface or It is extremely important to increase the heat insulation effect of the paper and improve the ink acceptability.
It has been found that it is important to provide a whitening effect on the surface of the image receiving layer, particularly to reproduce a more natural color tone of intermediate tones, and to obtain a clear and high-contrast transferred image.

That is, in addition to specifying the material constituting the thermal transfer recording image-receiving layer, the internal coupling strength (ie, Z-axis strength) of the image-receiving paper in the Z-axis direction and the reflection characteristic of the surface of the image-receiving layer are set within a specific range. The inventors have made adjustments and found that a synergistic effect of these conditions can provide a remarkable effect that cannot be predicted from the known art, and finally the present invention has been completed.

Further, by adjusting the Z-axis strength of the image receiving paper to a specific range to strengthen the paper layer and surface strength, troubles caused by paper dust can be prevented, and high speed recording and multicolor printing can be performed. It was found that an image-receiving paper for thermal transfer recording having an excellent image quality without a loss of transfer dots when being formed can be obtained.

The first feature of the image receiving paper for thermal transfer recording of the present invention is that the Z-axis strength according to TAPPI UM-403 is 0.05 to 0.18 ft.
lb, preferably by adjusting in the range of 0.06 ~ 0.16ft · lb, by imparting appropriate flexibility and cushioning property to the surface of the image receiving paper, the adhesion with the ink ribbon is increased, and the paper layer and the paper layer, Another object of the present invention is to obtain a homogeneous and clear recorded image having a high adhesive strength between the paper layer and the water-based coating layer serving as the image receiving layer, and free from uneven transfer and dot omission.

Generally, the Z-axis strength of an image receiving paper for thermal transfer recording is 0.
Some of them are 20 ft · lb or more, but such conventional thermal transfer recording image-receiving paper has insufficient cushioning and flexibility even if an image-receiving layer surface with good smoothness is formed. When transfer recording is performed by pressing the image receiving paper surface with the ink ribbon and the thermal head by the pressing pressure of the roll, the adhesion between the image receiving paper surface and the ink ribbon becomes non-uniform, resulting in uneven transfer and dot omission etc. However, the image quality was inferior.

Incidentally, if the Z-axis strength is less than 0.05 ft.lb, an image receiving paper having high strength of the surface of the paper layer and the image receiving layer desired in the present invention cannot be obtained, and generation of paper dust cannot be eliminated. Furthermore, when the ink ribbon and the image receiving paper are separated from each other during thermal transfer recording, the surface of the image receiving layer rolls up together with the transfer ink, and transfer dots (inks) are lost, which causes deterioration of image quality, which is not preferable. On the other hand, Z-axis strength is 0.18ft ・ lb
If it exceeds the above range, only an image receiving paper having poor cushioning property and flexibility as described above can be obtained, and a uniform and clear recorded image desired by the present invention cannot be obtained.

The method for adjusting the Z-axis strength of the image-receiving paper for thermal transfer recording within the range of the present invention is as follows: pulp fiber type, blending amount, beating condition, filler type and addition amount, paper strength enhancer type and addition. Amount, coating of surface sizing agents such as starch, polyvinyl alcohol, polyacrylamide, etc. or surface strength agents,
Examples include adjustment of dehydration conditions in a paper machine, wet press conditions, drying conditions, and the like, and an appropriate range can be adjusted by appropriately selecting these methods.

The second feature of the present invention is that the image-receiving paper for thermal transfer recording is measured in a state of containing fluorescent light according to the display method [L *, a *, b *] defined in JIS-Z-8729. The surface color is
It is to be adjusted within the range that satisfies the following conditions and. L * ≧ 90 1.7 (a * -1.5) ² +0.9 (b * + 5) ² +0.6 (a * -1.5) (b * + 5) ≦ 30

An illumination light source is, of course, required to see colors. In addition to natural light, the light source includes incandescent lamps, fluorescent lamps, halogen lamps, xenon lamps, mercury lamps, etc. as artificial light sources, and the color tone (color shade) of objects varies depending on the illumination conditions and observation conditions. Generally, the color tone is observed under a place where there is soft natural light, a fluorescent lamp that is illuminated, or the like.

The color tone of the transferred image obtained by thermal transfer is largely influenced by the color tone of the surface of the recording paper (hereinafter referred to as the reflection characteristic). For example, the transfer image obtained when the reflection characteristic of the recording paper is insufficient. Has a dull image quality. Also, the place where the transferred image is observed is usually a place where there is soft natural light or a place where there is illuminated light, so the degree of fluorescence coloring varies depending on the amount of ultraviolet light from the light source, and depending on the place of observation, the image receiving paper It is also a fact that the color tone of the transferred image is considerably deviated due to the influence of the reflection characteristic of the surface.

JIS-Z-8722 (a method for measuring an object color in a two-degree visual field) is generally well known as a method for measuring the reflection characteristics of a reflective object such as paper. Has not been applied. The present inventors have found that when evaluating a transfer image obtained by a thermal transfer recording method, it is extremely important to evaluate the color tone in a state in which the fluorescent color is added in order to accurately express the substance. It was found that it is important to adjust the reflection characteristics of the surface of the image receiving paper for thermal transfer recording, which has a great influence on the transferred image, in the state of including the fluorescent coloring.

By the way, reproducing more natural colors,
Needless to say, it is desirable to bring the image receiving paper as close to "white" as possible in order to obtain a clear and high-contrast transferred image. However, according to the results of studies by the present inventors, it has been found that the desired transfer image of the present invention can be obtained only when the reflection characteristics of the image receiving paper surface are vivid and slightly bluish. However, the importance of simultaneously satisfying the above conditional expressions and has been found. When the expression on the left side of the conditional expression is called the hue index S, S is an index for characterizing the hue of the image receiving paper.

The value of L * is called the lightness index and indicates the brightness of the color. It is usually displayed in the range of 0 to 100, where 0 means ideal black and 100 means ideal white. Also, a *, b
The value of * is called chromaticity (also called chromaticness index) and is displayed in the range of -100 to +100. Chromaticity a *
Indicates that the larger the value on the positive side, the stronger the degree of red, and the larger the value on the negative side, the greater the degree of green. On the other hand, the chromaticity b * indicates that the larger the value on the positive side, the stronger the degree of yellow, and the larger the value on the negative side, the greater the degree of blue. In general, a hue is represented by a coordinate position with a * on the horizontal axis and b * on the vertical axis. When both a * and b * are 0, it means that the color is achromatic.

Incidentally, when the value of L * is less than 90, the image transferred to the image receiving paper looks black and the sharpness is poor. on the other hand,
If S exceeds 30, the image receiving paper will more strongly feel the hue, for example, redness or blueness, rather than "whiteness", and the image receiving paper can accurately reproduce the original color tone of the transferred image. become unable. Therefore, in the present invention, L * ≧ 90,
It is important that S ≦ 30. And more preferably L * ≧ 93, H ≦ 20, and most preferably L * ≧ 93, S ≦
It is desirable to adjust to 15.

As a method of adjusting the reflection characteristics of the surface of the image-receiving paper for thermal transfer recording, a method of adding a colorant and / or a fluorescent whitening agent to the paper material constituting the image-receiving paper, or coating or impregnation on the base paper A convenient method is to add a colorant and / or a fluorescent whitening agent to the aqueous coating liquid to form the image-receiving layer, and adjust accordingly.

As the colorant in that case, for example, CI Direct Violet 1, the same 7, the same 9, the same 12, the same 35, the same
47, the same 48, the same 51, the same 90, the same 94, CI Direct Blue 1, the same 2, the same 6, the same 8, the same 15, the same 22, the same 25, the same 71, the same 7
6, 78, 86, 98, 108, 120, 158, 192
, 194, 195, 196, 199, 200, 201
, Ibid 202, ibid 203, ibid 207, ibid 236, ibid 237, ibid 246
, CI Direct Red 1, same 2, same 4, same 9, same 1
1, the same 13, the same 20, the same 23, the same 24, the same 28, the same 31, the same 33, the same 3
7, 39, 44, 46, 62, 75, 79, 80, 8
1, 83, 84, 89, 113, 197, 224, 225
, 226, 227, 230 CI Direct Yellow 1
2, the same 26, the same 28, the same 44, the same 50, the same 85, the same 86, the same 88, the same 100
, 142, CI Direct Orange 8, 39, 107
, CI Direct Brown 2, the same 6, the same 44, the same 173, the same
Direct dyes such as 195, CI Direct Green 6, 33 and 37. CI Acid Violet 35, 41, 49, CI
Acid Blue 9, the same 22, the same 40, the same 59, the same 102, the same 120
, CI Acid Red 1, 32, 37, 51, 52,
Same 80, same 87, same 92, same 94, CI Acid Yellow 11, same
Acid dyes 17, 17, 23, 25, CI Acid Orange 7, CI Acid Brown 14, CI Acid Green 3, 25, etc. CI Basic Violet 1, the same 14, CI Basic Blue 1, the same 5, the same 7, the same 9, the same 25, the same 26, CI
Basic Red 1, Same 2, Same as 12, CI Basic Yellow 11, Same as 14, CI Basic Orange 2, Same as 15, CI
Water-soluble dyes such as basic dyes such as Basic Brown 1, CI Basic Green 1, and 4 can be used.

Further, CI Pigment Violet 1, the same 3, the same 19, the same 23, the same 38, CI Pigment Blue 1, the same 2, the same 15, CI Pigment Red 2, the same 3, the same 5, the same 2
2, 23, 81, 112, 114, 146, 150, 1
70, CI Pigment Yellow 1, the same 3, the same 5, the same 12,
Azo pigments such as 13, 13, 14, 17, 55, 81, 83, 97, CI Pigment Orange 1, 13, 16, CI Pigment Green 4, 7, and 36, and disazo pigments Organic coloring pigments such as pigments, naphthol pigments, phthalocyanine pigments, quinacridone pigments, dioxazine pigments, quinophthalone pigments, isoindoline pigments, slene pigments, anthraquinone pigments, perinone pigments, dyed lake pigments, etc. CI Pigment Violet 16, CI Pigment Blue 27, 28, 29, CI Pigment Red 101, 10
4, 105, 106, 108, CI Pigment Yellow 34, 35, 37, 42, 53, CI Pigment Orange 21, CI Pigment Green 17, iron pigments such as 18.
Inorganic coloring pigments such as lead pigments, cadmium pigments, chromium pigments, cobalt pigments, ultramarine blue and dark blue can be used.

Among these dyes and color pigments, organic dyes such as direct dyes, azo pigments, disazo pigments, naphthol pigments, phthalocyanine pigments and dioxazine pigments which have a strong affinity for pulp fibers are It is preferably used because of its vivid color tone and excellent color development and light resistance.

Examples of the fluorescent whitening agent include CI Fluorescent 9, 24, 30, 30, 32, 37, 52, 54, and CI
84, same 85, same 86, same 87, same 90, same 91, same 92, same 104, same
121, same 134, same 153, same 164, same 166, same 167, same 168
, 169, 172, 173, 174, 175, 176,
177, 178, 216, 218, 223, 224, 2
25, same 231, same 239, same 240, same 241, same 242, same 264
Examples thereof include stilbene-based, distilbene-based, coumarin-based, pyrazoline-based, imidazole-based, oxazole-based, triazole-based, and naphthalimide-based fluorescent whitening agents. And among these, the fluorescent whitening agent consisting of 4,4'-bis (triazinylamino) stilbene-2,2'-disulfonic acid derivative is excellent in the effect of expressing fluorescent color and reproduces a more natural whiteness. Therefore, it can be preferably used, and particularly 4,4'-bis [2- (2,5-disulfoanilino) -4-
The optical brightener represented by the structural formula of bis (2-hydroxyethyl) amino-1,3,5-triazinyl-6-amino] stilbene-2,2'-sodium disulfonate is an ordinary optical brightener. As there is no phenomenon in which the whitening effect decreases and the whitening effect decreases, that is, the so-called quanting phenomenon, the effect of improving the fluorescent whitening is dramatically demonstrated, and paper materials and water-based coatings are used. It is most preferably used because it exhibits excellent stability against liquids.

When these colorants and / or optical brighteners (hereinafter, the colorants and / or optical brighteners are simply referred to as brightening agents) are added to the stock constituting the image-receiving paper, Generally, it is used by adding it to a slurry-like paper material (pulp fiber) together with a filler and various internal additives for papermaking. The method of adding the brightening agent, the place of addition, the addition procedure, etc. are not particularly limited,
Also, the amount of addition is adjusted according to the desired reflection characteristics of the surface of the image receiving layer, and is not particularly limited. Normally 0.0001 for absolutely dry pulp fiber
It is added in the range of about 0.1% by weight.

The filler is a publicly known white pigment generally known in the art, and is not particularly limited. For example, talc, kaolin, clay, deramikaolin, calcined kaolin, heavy calcium carbonate, light calcium carbonate, carbonic acid. Magnesium, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, magnesium sulfate, calcium silicate, calcium sulfate, diatomaceous earth, calcined diatomaceous earth, silica, white carbon, aluminosilicate, sericite, bentonite , One or more kinds of fillers such as mineral fillers such as smectite, fine particles such as polystyrene resin, urea resin, acrylic resin, melamine resin and benzoguanamine resin, and organic synthetic fillers such as minute hollow particles are appropriately selected. It can also be used in combination, and even used paper and Filler contained in the stroke and the like is also possible to reuse. A filler having a whiteness of powder of 75% or more, preferably 80% or more is effective for the effect of improving the whiteness of recording paper, and thus can be desirably used.

Further, according to the results of the study by the present inventor, among these fillers, the apparent specific gravity according to JIS-K-6220 (hereinafter simply referred to as apparent specific gravity) is 0.10 to 0.50. g / cm
^3, preferably 0.15~0.40g / cm ³ porous pigments encompassed a large amount of air to the particles, moderate by such pigments (fillers) is conveniently inherent in between pulp fibers It is possible to impart various voids and cushioning properties to the base paper, and as a result, the heat insulating properties of the base paper are remarkably improved, and the opacity and smoothness are effectively improved, and the quality as an image receiving paper for thermal transfer recording is improved. The characteristics are dramatically improved. Therefore, the use of such a porous pigment is one of the preferred embodiments of the present invention.

Incidentally, among the porous pigments, the apparent specific gravity is
If it exceeds 0.50 g / cm ³ , the properties of the porous pigment are reduced by half, the voids in the base paper are reduced, and a dense paper layer structure is formed, resulting in a sharp decrease in the heat insulation efficiency of the base paper. As a result, the receptivity and fixing property of the transfer ink are deteriorated, and it is impossible to obtain a clear image-receiving sheet for thermal transfer recording which is free from the uneven transfer and missing dots desired by the present invention. Further, since the fine voids required for light scattering are reduced, the opacity is significantly reduced. On the other hand, in the case of a porous pigment of less than 0.10 g / cm ^3, the voids in the base paper increase and the heat insulation properties are given more than necessary, making it difficult for the heat from the thermal head to be cooled on the surface of the image receiving layer, and heat storage. As a result, the bleeding of the transfer ink and the bridging phenomenon are induced, and the image quality deteriorates. Further, since the paper layer strength becomes extremely weak, it is not preferable because the transfer dots are lost and the image quality is deteriorated due to the paper dust.

Further, even with the above specific porous pigment,
When the amount used is less than 6% by weight with respect to the absolutely dry pulp constituting the base paper, the desired effect of the present invention cannot be obtained.
When the content is more than 5% by weight, the strength of the paper layer of the base paper becomes weak and paper dust is generated to adversely affect the image quality, which is not preferable.

Specific examples of the porous pigment include white carbon, amorphous silica, fine particle calcium silicate, fine particle magnesium carbonate, fine particle alumina, zeolite, magnesium aluminosilicate, calcined kaolin, diatomaceous earth and calcined diatom. Examples thereof include soil and sea urchin-like or spherical light calcium carbonate formed by agglomeration of a plurality of single particles. Then, among these, a porous pigment satisfying the specific conditions is used. Among these pigments, especially the sea urchin-like or spherical light calcium carbonate is excellent in the fixing property of the transfer ink and the reproducibility of the dot shape, and moreover, the color reproducibility at the time of multicolor overprinting is good, so that the color misregistration is caused. Since an image receiving paper for thermal transfer recording having excellent gradation is obtained, it can be preferably used.

The pulp fiber is not particularly limited and is mainly composed of ordinary wood pulp fiber, and if necessary, non-wood pulp fiber such as kenaf, bamboo, hemp, etc., polyester or polyolefin. Synthetic pulp,
Alternatively, synthetic fibers and further inorganic fibers such as glass fibers and ceramic fibers can be used. The type of pulp fiber, the manufacturing method, etc. are not particularly limited, and examples include KP and S
In addition to chemical pulp fibers such as softwood pulp and hardwood pulp obtained by the P and AP methods and SCP, various high-yield pulps (SGP, BSGP, BCTMP, CTMP, CGP, TMP, RGP,
CMP, etc.) or waste paper pulp such as DIP or recycled pulp. Among these, for example, Kaede,
Chemical pulp fibers obtained from hardwood such as birch, oak, oak, beech, aspen, and eucalyptus have excellent cushioning properties and heat insulating properties, and are particularly effective in improving ink acceptability. it can.

It should be noted that, in addition to pulp fibers and fillers as main components, the stock contains various retention aids and filters conventionally used in the art, as long as the desired effects of the present invention are not impaired. An internal additive for papermaking such as a water improver, a paper strength enhancer, and a sizing agent is appropriately selected and used as necessary. Further, it is also possible to appropriately add an internal additive for papermaking such as a pH adjusting agent, a defoaming agent, a pitch control agent and a slime control agent.

The papermaking method is not particularly limited. For example, an acidic papermaking method having a papermaking pH of about 4.5, a weak pH of about 6 to about 9 with an alkaline filler such as calcium carbonate as a main component. The present invention can be applied to all papermaking methods such as the so-called neutral papermaking method in which the material is weakly alkaline.
Further, as the paper machine, a Fourdrinier paper machine, a twin wire paper machine, a round wire paper machine, a Yankee paper machine or the like can be appropriately used.

When the brightening agent is applied or impregnated on the base paper, for example, one of the brightening agents described above may be used alone or in combination, and the brightening agent may be diluted with water to prepare an aqueous solution or an aqueous dispersion, and then applied on the base paper. Although the method of impregnation is possible, the method of adding it to an aqueous coating liquid containing an adhesive is more preferable. In this case, the coating amount of the brightening agent is adjusted according to the desired reflection characteristics of the image receiving layer surface, and is not particularly limited, but usually 0.0001 to 1.0 per one side in absolute dry weight. g
/ M ² or so.

It is preferable to include an adhesive as a coating composition in the aqueous coating liquid, and the adhesive in this case means a water-soluble and / or water-dispersible polymer compound, It is not particularly limited. For example, oxidized starch,
Enzyme-modified starch, thermochemically modified starch, starch such as esterified starch, and natural or semi-synthetic polymer compounds such as carboxymethyl cellulose, hydroxyethyl cellulose, gelatin, casein, soybean protein, natural rubber; polyvinyl alcohol, polyvinyl acetate, polyvinyl Pyrrolidone, polyvinyl butyral, polypropylene, polyethylene, poly (meth) acrylamide, poly (meth) acrylic acid ester, polyester, polyamide, polyurethane and other synthetic resins, styrene / butadiene, methylmethacrylate / butadiene, acrylonitrile / butadiene,
Examples of the adhesive include synthetic polymer compounds such as chloroprene-based synthetic rubbers, and one or more of them are appropriately selected and used according to the quality target of the image receiving paper for thermal transfer recording.

Further, in order to obtain an image receiving paper for thermal transfer recording capable of enhancing the ink receptivity and exhibiting a desired high image quality, in addition to the above adhesive, an aqueous coating liquid containing a pigment is applied or It is preferred to impregnate and provide an image receiving layer.

As the pigment in this case, various pigments used for general coated paper, for example, kaolin, deramikaolin, aluminum hydroxide, satin white, light calcium carbonate, heavy calcium carbonate, calcium sulfate, barium sulfate, and dioxide. Titanium, calcined kaolin, talc, zinc oxide, zinc carbonate, alumina, diatomaceous earth, magnesium oxide, magnesium carbonate, silica, white carbon,
Mineral pigments such as magnesium aluminosilicate, colloidal silica, bentonite, zeolite, sericite and polystyrene resin, fine particles such as urea resin, melamine resin, acrylic resin, benzoguanamine resin, and fine hollow particles and other organic pigments. Among them, one kind or two or more kinds are appropriately used in combination according to the quality target of the image receiving paper for thermal transfer recording. The amount of the pigment is preferably 0 to 95% by weight, and more preferably 10 to 90% by weight based on the solid content in order to obtain the desired effects of the present invention. Further, when a pigment is contained, it is desirable to use a powder having a whiteness of 75% or more, preferably 80% or more, because the whiteness of the recording paper can be improved.

In the aqueous coating liquid, in addition to these, various auxiliaries such as a surfactant, a pH adjusting agent, a viscosity adjusting agent, a softening agent, a glossing agent, a dispersing agent, a flow modifier, an antistatic agent, Waxes, stabilizers, ultraviolet absorbers, antistatic agents, cross-linking agents, sizing agents, defoaming agents, water-proofing agents, plasticizers, lubricants, preservatives, fragrances and the like can be appropriately used if necessary. ..

The coating liquid thus prepared is coated or impregnated on one side or both sides of the base paper. The coating amount or impregnating amount is not limited as long as the desired effect of the present invention is satisfied. In general, it is not necessary to increase the amount unnecessarily, and the dry weight is generally 0.5 to 15 g / m ² , preferably about 1 to 10 g / m ² per one side. In forming the image-receiving layer by coating or impregnating the base paper with the aqueous coating liquid, whether the layer is a single coating of the aqueous coating liquid or a multilayer structure having two or more layers. Is not particularly limited. Further, in the case of a multi-layer structure, the composition of the coating liquid for each layer does not have to be the same, and is appropriately adjusted according to the required quality level.

The coating or impregnating apparatus is not particularly limited, and examples thereof include a blade coater, an air knife coater, a roll coater, a reverse roll coater, a bar coater, a curtain coater, a die slot coater, a gravure coater, and a chanter. A plex coater, a brush coater, a two-roll or metering blade type size press coater, a bill blade coater, a short dwell coater, a gate roll coater, an apparatus such as a spray or pre-wet method or a float method can be appropriately used. Of course,
These devices may be on-machine or off-machine coaters.

The thus-prepared image-receiving paper for thermal transfer recording is subjected to smoothing treatment in a usual drying step or surface treatment step, and finished with a water content of 3 to 10% by weight, preferably 4 to 8% by weight. Be done. When the thermal transfer recording image receiving paper is smoothed, a normal smoothing device such as a super calender, a gloss calender or a soft calender is appropriately used. Particularly, if a smoothing treatment is carried out by passing the paper between a pressure nip composed of a metal roll heated to 50 ° C. or higher, preferably 80 ° C. or higher and a heated or unheated elastic roll, further desirable results can be obtained. .. It is appropriately used in on-machine or off-machine, and the form of the pressurizing device, the number of pressurizing nips, and the like are appropriately adjusted according to a normal smoothing processing device.

[0045]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, "part" and "%" in an example show "weight part" and "weight%", respectively, unless there is particular notice.

Example 1 [Preparation of base paper] 10 parts of NBKP (material / spruce; freeness = CSF 520 ml) and 90 parts of LBKP (material / maple; freeness = CSF 480 ml) were mixed in a pulp slurry and calcined kaolin as a filler [see Hanging specific gravity = 0.30 g / cm ² ]
A stock was prepared by adding 15 parts, 1.5 parts of rosin emulsion sizing agent, and 2 parts of sulfuric acid band. This stock was made using a twin-wire paper machine, and then applied with a size press machine so that the applied amount of oxidized starch was 2 g / m ^{2 in} dry weight, and dried to obtain a rice weighing of 85 g / m ² . I got a base paper.

[Preparation of coating liquid] Spindle-shaped light calcium carbonate 90 parts (solid content; the same as below) and sodium oxide polyacrylate 0.4 part (solid content ratio to pigment; same below) were added to 10 parts of titanium oxide, Water was dispersed using a disperser to prepare a pigment slurry. Add 15 parts of polyvinyl alcohol, 4 parts of styrene-butadiene type synthetic rubber, stilbene type optical brightener (CI Fluorescent 264) to this pigment slurry.
Parts were added and stirred, and water was further added to prepare a coating liquid having a solid content concentration of 50% by weight.

[Formation of Image Receiving Layer] This coating solution is coated on both sides of the above-mentioned base paper using a bar coater so that the total coating amount is 10 g / m ^{2 in} dry weight, and the temperature is Paper is passed through a pressure nip (nip number 11, nip linear pressure 200Kg / cm) composed of metal roll and elastic roll at 50 ℃
An image receiving paper for thermal transfer recording of m ² was obtained.

Example 2 In the preparation of the coating liquid of Example 1, the amount of the stilbene-based optical brightening agent was reduced to 2 parts, and 0.01 part of a dioxazine-based organic color pigment (CI Pigment Violet 23) was newly added. An image receiving paper for thermal transfer recording having a basis weight of 95 g / m ² was obtained in the same manner as in Example 1 except that the coating liquid was prepared in the same manner as in Example 1.

Example 3 In the preparation of the base paper of Example 2, the filler was changed to 18 parts of talc [apparent specific gravity = 0.75 g / cm ² ] and the basic dye (CI Basic Violet 1) was added. To 0.0004 parts to prepare a paper stock, and in the preparation of the coating liquid, the same procedure as in Example 2 was carried out except that the coating liquid was prepared by reducing the amount of the stilbene optical brightener to 1.2 parts. An image receiving paper for thermal transfer recording having a basis weight of 95 g / m ² was obtained.

Example 4 In the preparation of the base paper of Example 2, sea urchin-like light calcium carbonate [apparent specific gravity = 0.38 g / c] was added to the pulp slurry as a filler.
m ² ], 14 parts, direct dye (CI Direct Violet 3
5) 0.003 parts, sulfuric acid band 0.5 parts, cationic starch 1.5 parts, alkenyl succinic anhydride 1.0 part, and retention improver 0.05 parts were changed to prepare paper stock. In the same manner as in Example 2, an image receiving paper for thermal transfer recording having a basis weight of 95 g / m ² was obtained.

Example 5 In Example 4, a base paper was prepared by reducing the amount of the filler to 7 parts of sea urchin light calcium carbonate, and then 1.2 parts of the stilbene optical brightener was prepared in the preparation of the coating liquid. Weight loss on addition,
And 0.02 parts of the dioxazine-based organic coloring pigment was added, and 0.01 parts by weight of naphthol-based organic coloring pigment (CI Pigment Red 150) was newly added to prepare a coating liquid, and the same procedure as in Example 4 was performed. An image receiving paper for thermal transfer recording having a basis weight of 95 g / m ² was obtained.

Example 6 In Example 4, the filler was amorphous silica (apparent specific gravity = 0.
20 g / cm ² ] and spindle-shaped light calcium carbonate [apparent specific gravity = 0.
59 g / cm ² ] mixed filler (mixing ratio 1: 1) was changed to 20 parts, and 0.0005 parts of a direct dye (CI Direct Red 81) was newly added to prepare a base paper, and then coated. In preparation of the liquid, an image receiving paper for thermal transfer recording having a basis weight of 95 g / m ² was obtained in the same manner as in Example 4 except that the coating liquid was prepared by adding 0.04 parts of the dioxazine-based organic color pigment. ..

Comparative Example 1 The same procedure as in Example 1 was carried out except that the coating solution was prepared without adding the fluorescent whitening agent, and the weight of rice was 95 g / m 2.
^The image receiving paper for thermal transfer recording of No. ² was obtained.

Comparative Example 2 In Example 3, a stock was prepared by adding 0.001 part of the basic dye to prepare a coating material, and then a coating solution was prepared without adding an optical brightening agent in the preparation of the coating solution. An image receiving paper for thermal transfer recording having a basis weight of 95 g / m ² was obtained in the same manner as in Example 3 except for the above.

Comparative Example 3 In Example 1, the filler was kaolin (apparent specific gravity = 0.60 g).
/ cm ² ] was changed to 25 parts by weight to prepare a base paper, and in the preparation of the coating liquid, the amount was reduced to 1 part by weight of a stilbene-based optical brightener, and a phthalocyanine-based organic coloring pigment (CI Pigment Green 7) newly added 0.01 parts of a coating except that the liquid was prepared, in example 1 the basis weight in the same manner as in the 95 g / m ²
An image receiving paper for thermal transfer recording was obtained.

Comparative Example 4 In Example 5, the filler was a spindle-shaped light carbon [apparent specific gravity = 0.59].
g / cm ² ] was changed to 16 parts to prepare a base paper, and then in the preparation of the coating liquid, the coating liquid was prepared by increasing the amount of the naphthol-based organic color pigment to 0.05 part. In the same manner as in Example 5, an image receiving paper for thermal transfer recording having a basis weight of 95 g / m ² was obtained.

Comparative Example 5 In Comparative Example 4, a paper stock was prepared by changing the dye to 0.002 parts of the direct dye (CI Direct Blue 86), and then, in the preparation of the coating liquid, 3 parts of the fluorescent whitening agent were used. 95 g of rice per square meter was prepared in the same manner as in Comparative Example 4 except that the coating liquid was prepared without adding the naphthol-based organic color pigment.
An image-receiving paper for thermal transfer recording of / m ² was obtained.

Comparative Example 6 In the preparation of the base paper of Example 5, the filler was reduced to 5 parts of sea urchin light calcium carbonate, and 0.3 part of cationic polyacrylamide was newly added as a paper strength enhancer. As in Example 5, except that the paper was prepared,
An image receiving paper for thermal transfer recording having a g / m ² was obtained.

The 12 types of image-receiving papers for thermal transfer recording thus obtained were measured and quality-evaluated by the following methods. The obtained results are shown in Table 1.

(Measurement of Z-axis strength) Using an internal bond tester (manufactured by EH Benz), TAPPI
Z-axis strength (ft · lb) was measured according to UM-403.

(Measurement of Reflection Characteristic of Paper Image Receiving Layer Surface) Using EL REFO 2000 (manufactured by Data Color Co., Ltd.), lightness (L *) and chromaticity (a *) of the image receiving layer surface in a state of containing fluorescence. , B *) was measured. The hue index S referred to in the present invention is obtained by the following equation. S = 1.7 (a * -1.5) ² + 0.9 (b * + 5) ² + 0.6 (a * -1.5) (b * + 5)

(Measurement of Image Density) A thermal transfer color printer (CHC-443 type / manufactured by Shinko Electric Co., Ltd.) was used to record and obtain a test pattern having rainbow, grid, halftone dots and gradation recording. The density of the black solid portion of the recorded image was measured with a Macbeth densitometer (RD-100 R type / manufactured by Macbeth).

(Evaluation of Image Quality of Recording Surface) With respect to each recording portion of the recording surface, the quality of the recorded image was visually comprehensively evaluated according to the following evaluation criteria. ◎: There is no color shift or uneven density,
The color tone is very vivid and the natural color tone is reproduced, and the image quality is excellent. ◯: Almost no color misregistration or unevenness of light and shade, the color tone is vivid, and the natural color tone is reproduced, and the image quality is good. Δ: Color misregistration and uneven density are observed, the color tone is not satisfactory, and the image quality is poor.

(Evaluation of dot reproducibility on recording surface) The halftone dot portion of the above recording surface was measured with a dot analyzer (DA-3000).
The image was magnified twice, and the degree of dot omission and sharpness (bleeding) was visually evaluated according to the following evaluation criteria. ⊚: The dots are sharp and there is no omission, which is extremely excellent. ◯: Good with almost no dot bleeding or omission. Δ: There is bleeding or omission of dots and it is slightly inferior. X: Many dots are bleeding or missing and inferior.

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[Table 1]

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As is clear from the results of the examples, the image-receiving paper for thermal transfer recording of the present invention has a high recording density, reproduces a natural color tone, has a vivid color tone, and
It is a high-quality, high-quality image receiving paper for thermal transfer recording with excellent dot reproducibility.

Claims (6)

[Claims] 1. A thermal transfer recording image-receiving paper comprising a base paper coated with or impregnated with an aqueous coating liquid to form an image-receiving layer.
Z-axis strength according to PPI UM-403 is 0.05 ~ 0.18ft · lb,
An image-receiving paper for thermal transfer recording, characterized in that the surface of the image-receiving layer is measured under the condition that it contains fluorescent light based on the display method defined in JIS-Z-8729 and the following conditions are satisfied at the same time. L * ≧ 90 1.7 (a * -1.5) ² +0.9 (b * + 5) ² +0.6 (a * -1.5) (b * + 5) ≦ 30 2. The image-receiving paper for thermal transfer recording according to claim 1, wherein the porous pigment contained in the base paper has an apparent specific gravity of 0.10 to 0.50 g / cm ³ according to JIS-K-6220. 3. The image-receiving paper for thermal transfer recording according to claim 1, wherein the base paper contains a colorant and / or a fluorescent whitening agent. 4. The image-receiving paper for thermal transfer recording according to claim 1, wherein the image-receiving layer contains a colorant and / or a fluorescent whitening agent. 5. The image receiving paper for thermal transfer recording according to claim 3, wherein the fluorescent brightening agent is a 4,4′-bis (triazinylamino) stilbene-2,2′-disulfonic acid derivative. 6. The image receiving paper for thermal transfer recording according to claim 1, wherein the aqueous coating liquid is a coating composition containing a pigment and an adhesive as main components.