JPH06247059A - Heat transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To prevent the dots omission of transferred image, nonuniform density and the like from developing by a method wherein base material for support is made from base paper, in which the standard deviation of the mass variation due to wire marks and that due to the dispersion of fibers are respectively represented by specified values. CONSTITUTION:The heat transfer image receiving sheet used in a device utilizing heat transfer recording system such as color hard copy or the like has image receiving layer for receiving dye, which is transferred heat transferring medium through heat solvent or sublimation at heating, on at least one side of support. In this case, as the base paper used in some part of the support, the base paper having the standard deviation of the mass variation due to wire marks of 1.0g/m<2> or less that due to the dispersion of fibers of 4.0g/m<2> or less is employed. Further, in the support, resin covered paper prepared by covering with polyolefin resin is used in the base material for the support. Thus, image receiving sheet, in which the dots omission of transferred image, nonuniform density and the like do not develop, is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving sheet, and more particularly to a thermal transfer image-receiving sheet free from missing dots and uneven density in a transferred image.

[0002]

2. Description of the Related Art In recent years, as a means for color hard copy, an apparatus using a thermal transfer recording system has been widely used because of its advantages such as light weight, compact size, no noise, excellent operability and maintainability. . This thermal transfer recording system is roughly classified into two types, which are a heat melting type and a heat transfer type or a sublimation type. In particular, the latter is excellent in reproducibility of multicolor gradation images and is printed by using a sublimation type thermal transfer type printer. The principle of such a sublimation type thermal transfer type printer is that an image is converted into an electric signal, and further this electric signal is converted into a heat signal by a thermal head, and a heat transfer medium coated with a heat transferable dye (hereinafter , An ink donor sheet) is heated and dye is transferred from the ink donor sheet to the image-receiving layer of the thermal transfer image-receiving sheet by sublimation or diffusion in a medium, thereby recording information. As a support for the thermal transfer image-receiving sheet, polyolefin resin-coated paper, synthetic paper or laminated paper with a synthetic film is generally used. A thermal transfer image-receiving sheet using a support such as laminated synthetic paper or synthetic film is disclosed in JP-A-63-290790 and 63-231.
As described in Japanese Patent Publication No. 984, etc., the quality of the transferred image is relatively high because of its good smoothness and heat insulation, but on the other hand, it is costly. Therefore, JP-A-6
0-236794, U.S. Pat. No. 5,059,58.
If a polyolefin-coated paper as described in No. 0 or the like is used as a support, it is a low-cost image-receiving sheet for thermal transfer whose appearance and feel are similar to paper.
The needs are also strong.

[0003]

However, with respect to the support using the base paper as a part of the support, uneven formation of the base paper, density unevenness, that is, local mass variation is caused by the thermal head at the time of printing. Since it affects the adhesion of the printed image, dot loss of the transferred image, non-transferred image of a larger area, so-called uneven density of the transferred image, etc. occur, and the quality is remarkably impaired. In particular, in recent years, it has been required to improve the transfer density from the viewpoint of increasing the printing speed, and as one means for achieving such high sensitivity, it is necessary to increase the pressure between the thermal head and the platen roll, that is, the platen pressure. The method of reducing the applied energy loss between the thermal head and the thermal transfer image-receiving sheet that is pressed against the thermal head is used, but if the paper mass fluctuation is large, dot omission and density unevenness will occur. As a result, the quality of the transferred image is further deteriorated.

[0004]

Means for Solving the Problems As a result of intensive studies by the present inventors, a fine mass variation with a wavelength of 1 mm or less in a base paper causes a dot dropout in a transferred image when printing is performed by a sublimation type thermal transfer printer. It was also found that a relatively large mass variation such that the wavelength on the base paper exceeds 1 mm influences the density unevenness of the transferred image.

Therefore, the present invention provides a thermal transfer image-receiving sheet in which at least one of the supports is provided with an image-receiving layer for receiving a dye which migrates from the thermal transfer medium by heat melting or sublimation upon heating. An object of the present invention is to provide an image-receiving sheet for thermal transfer, which is free from missing dots and uneven density of a transferred image by making the mass distribution of the body substrate uniform.

The present inventors have investigated in detail the relationship between dot loss and density unevenness of a transfer image and a mass image obtained from β rays or transmission rays of a support base material, Standard deviation of mass variation due to wire mark is 1.0
When it is g / m ² or less and the coefficient of mass variation due to fiber dispersion is 4.0 g / m ² or less, a good thermal transfer image-receiving sheet free from missing dots in the transferred image and uneven density can be obtained. The present invention has been completed and the present invention has been completed.

Further, the thermal transfer image-receiving sheet of the present invention is characterized in that the support is a resin-coated paper obtained by coating a support base material with a polyolefin resin.

Here, the mass distribution of the base material for the support does not mean a general formation represented by fluctuations in the transmittance of visible light, laser light and the like. That is, the change in light transmittance is
It is commonly used as a substitute index for mass fluctuation,
A. KOMPPA was published by Paperi Puu magazine (1
As described in No. 3, 1988, p. 243), in lightly beaten paper or paper subjected to calendering, the change in light transmittance may not necessarily correspond to the change in mass.

The mass image of the base material for the support in the present invention is as follows. NORMAN and D.I. WAHREN is Svens
k Paperstidning. Magazine (7 July 1972)
Β-radiograph as described in Vol. 5, No. 29, p. E. FARRINGTON. Jr is Ta
ppi Journal magazine (May 1988 issue 140)
It can be obtained by a method using a soft X-ray radiograph, etc. By using radiation that is less scattered than light and has excellent mass-correlation of transmittance, it is possible to obtain a light and shade that responds to mass fluctuations without being affected by density fluctuations of the base material for the support and optical properties of pulp. An image is obtained. still,
It is possible to calibrate a grayscale image into a mass image by imprinting a standard step wedge of known mass into the film at the same time as the sample when photographing the β radiograph or soft X-ray radiograph.

In the present invention, the standard deviation of the mass fluctuation derived from the dispersion of the wire mark and the fiber is such that the mass image is two-dimensionally Fourier transformed by an image analyzer under the condition that one pixel is 0.1 mm square and the periodicity is determined. The peaks in the power spectrum from the wiremarks of the above are separated from the other components of the power spectrum from the dispersion of the aperiodic fiber, and then the standard deviation of the mass variation is measured for each inverse Fourier transform image. Required by Details of this method are described in H. Praast and L.M. GOTTSCHI
Reported by NG. (Das Papier
Magazine (1987, Vol. 41 No. 3, page 105))

As a specific method for producing the base material for the support of the support of the present invention, the following methods can be used alone or in combination. (1) The freeness (csf) of the headbox material is 150
The weight average fiber length is 0.45 to 0.65 at ~ 300 ml.
Use mm pulp. (2) Use 2.5-fold or 3-fold woven plastic wire for paper making. These wires are used in the paper and pulp technology Times magazine (May 1988, 15
A wire having a cross-sectional structure of more than two layers, as described in (Page). (3) Manufactured with a hybrid former. A hybrid former is, for example, a journal of Japan Pulp and Paper Technology Association (198
This is a Fourdrinier paper machine having an upper dewatering mechanism as described in the July 8 issue, page 23).

The base material for the support constituting the support of the present invention is usually used in papermaking such as a filler, a dye, a sizing agent, a dry paper strength enhancer, a wet paper strength enhancer, a fixing agent and a yield improving agent. Additives can be included as needed. Surface treatment with starch, polyvinyl alcohol, gelatin, etc., and antistatic treatment with Glauber's salt, sodium chloride, aluminum chloride, organic conductive agents, etc. can be carried out on the base material for the support, if necessary.

The basis weight of the support base material of the present invention is 50 to 30.
It is 0 g / m ² , and it is possible to perform pressing or calendering treatment if necessary.

The support used in the present invention is preferably a substrate obtained by extrusion coating a polyolefin resin on at least one of the base materials for the support, that is, resin-coated paper, and if necessary, synthetic paper or synthetic resin. It is also possible to attach films, etc. Further, the base paper having the improved mass uniformity according to the present invention can be used as a support by itself.

As the polyolefin resin, there can be used polyolefin resins which are generally used in general such as low density polyethylene, high density polyethylene, low density polypropylene and high density polypropylene. The coating amount of the polyolefin resin is preferably ¹ to 30 g / m ² .

As the synthetic resin film, any of the commonly used porous or non-porous films such as polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene and polycarbonate can be appropriately used according to the purpose.

The image-receiving sheet for thermal transfer of the present invention comprises an image-receiving layer having a dyeing property to a dye which is melted or sublimated by heat and migrates, which is provided on a support. As the binder resin having a dye-dyeing property, any binder resin having a strong interaction with the dye and capable of stably diffusing the dye into the resin can be preferably used. For example, a polyester resin having an ester bond,
Polyacrylic ester resin, polycarbonate resin,
Polyvinyl acetate resin, styrene acrylate resin, etc .;
Polyurethane resin having a urethane bond; polyamide resin (nylon) having an amide bond; urea resin having a urea bond; and polycaprolactone resin, polystyrene resin, polyvinyl chloride , Polyacrylonitrile resin, etc. can be used. Further, it is also possible to use a copolymer containing at least one of the constitutional units of the above resin as a main component, for example, a vinyl chloride-vinyl acetate copolymer, a styrene-butadiene copolymer and the like. The resins may be used alone or in combination of two or more.

The above-mentioned resin can be dissolved in water or an organic solvent and applied on a support, or can be emulsified in an aqueous solution and applied as an emulsion. If necessary, the resin can be easily adhered to the support. It can be treated to improve the adhesion to the image receiving layer.

As a method for making the support easily adhesive, a method of modifying the surface of the support by corona discharge treatment, plasma treatment, or the like, or applying a resin having good adhesiveness to both the support and the image receiving layer Etc. As such a resin, any resin having good adhesiveness to both the support and the image receiving layer can be preferably used. For example, acrylic resin, vinyl chloride resin, vinyl acetate resin, urethane resin , A styrene-butadiene-based resin, or a copolymer thereof is preferable.

Further, on the side opposite to the image receiving layer of the support, a back surface layer containing an inorganic fine powder is provided in order to impart roll slipperiness during transfer and writing on the back surface, or the back coating layer. An antistatic agent may be added therein for the purpose of antistatic. When an adhesive resin is mixed in the back surface layer, it is also possible to mix the adhesive resin and an antistatic agent to cause bleeding on the resin surface, and as a result, to provide it on the resin layer. Examples of the antistatic agent include surfactants such as cationic surfactants (quaternary ammonium salts, polyamine derivatives, etc.), anionic surfactants (alkyl phosphates, etc.), zwitterionic surfactants, or nonionics. Type surfactants and the like.

In the present invention, a releasing agent can be added to the image receiving layer in order to prevent blocking with the ink donor sheet. Examples of such a releasing agent include higher fatty acids or esters thereof, amides or metal salts thereof, waxes such as shellac wax, montan wax, carnauba wax, polyethylene wax and Teflon powder; fluorine-based and phosphoric ester-based surfactants. Silicone oil, modified silicone oil such as amino-modified silicone, epoxy-modified silicone, alkyd-modified silicone, polyester-modified silicone, etc. are used. or,
As the silicone compound, a reaction-curable type, an ionizing radiation-curable type, a catalyst-curable type or the like can be used if necessary.

Further, if necessary, additives such as dyes, pigments, wetting agents, defoaming agents, dispersants, antistatic agents, fluorescent whitening agents, ultraviolet absorbers and light stabilizers are added to the image receiving layer. You can also do it. As the pigment, silica, alumina, titanium oxide, calcium carbonate, kaolin, clay, zinc oxide,
Inorganic particles typified by barium sulfate and the like can also be added.

In the present invention, the coating amount of the image receiving layer is preferably in the range of 0.5 to 30 g / m ² in terms of dry solid content. or,
As a method of providing the image receiving layer, an air knife coater,
Curtain coater, die coater, blade coater,
A gate roll coater, bar coater, rod coater, roll coater, bill blade coater, short dwell blade coater, etc. can be used.

[0024]

According to the present invention, a thermal transfer image-receiving sheet free from dot omission and density unevenness is obtained by using a paper having less mass fluctuation due to poor dispersion of wire marks or fibers as a base material for a support constituting the support. Is obtained. That is, the dot omission of the transferred image when printing with a sublimation type thermal transfer printer is caused by the wire mark having a wavelength of 1 mm.
The standard deviation of the following small mass fluctuations is set to 1.0 g / m ² or less, and the density deviation of the transferred image has a standard deviation of 4.0 on the relatively large scale due to the dispersion of the fibers.
It can be improved by setting it to g / m ² or less.

[0025]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the contents of the present invention are not limited to these. Also, "part" and "%" shown in the examples are
All are parts by weight and% by weight.

[Preparation of Ink Donor Sheet] A sublimation dye solution having the following composition was pulverized in a ball mill for 2 days, and then 1.
An ink donor sheet coated with 5 g / m ² was used for evaluation. Sublimation dye liquid formulation: Kayaset Blue 906 (Nippon Kayaku, sublimation dye) 10 parts Ethyl Semellose 10 parts Syloid 244 (Fuji Davison silica gel) 10 parts Isopropyl alcohol 30 parts

Example 1 Using a double disc refiner, a hardwood bleached kraft pulp beaten to a Canadian standard freeness of 240 ml and a softwood bleached pulp beaten to 280 ml were mixed at a ratio of 7: 3 by weight to 100 parts of the following: 150 g / m ² and a density of 1 by using a hybrid former (Bellbond former) that uses 2.5-fold weave plastic wire (LL70E, manufactured by Nippon Falcon Co., Ltd.) as a paper material by adding the additive mixture of A base paper of 0.01 g / cm ³ was obtained. The weight average fiber length of the cellulose fibers in the head box was 0.6 mm. This base paper was used as the base material for the support of Example 1. [Addition of additives] Higher fatty acid amide 0.3 part Cationic starch 2 parts Alkyl ketene dimer 0.3 part Polyamide epichlorohydrin resin 0.3 part

Example 2 The basis weight was 150 g / m ² and the density was 1.01 g / cm ^{3 in the same} manner as in Example 1 except that the raw paper was made by a Fourdrinier paper machine.
I got the base paper. This base paper was used as the base material for the support of Example 2.

Example ³ A base paper having a basis weight of 150 g / m ² and a density of 1.01 g / cm ^{3 was} prepared in the same manner as in Example 1 except that a double-woven plastic wire (LL400, manufactured by Nippon Falcon Co., Ltd.) was used. Obtained. This base paper was used as the base material for the support of Example 3.

Example 4 A base paper was produced in the same manner as in Example 1 except that the bleached hardwood sulfite pulp beaten to 120 ml at Canadian standard freeness (csf) was used. The base material thus obtained has a basis weight of 150 g / m ² and a density of 1.04 g / c.
It was m ³ . The weight average fiber length of the cellulose fibers in the head box was 0.4 mm. This base paper was used as the base material for the support of Example 4.

Example 5 A base paper was produced in the same manner as in Example 2, except that the bleached hardwood sulfite pulp beaten to 120 ml at Canadian standard freeness (csf) was used. The base material thus obtained has a basis weight of 150 g / m ² and a density of 1.03 g / c.
It was m ³ . The weight average fiber length of the cellulose fibers in the head box was 0.4 mm. This base paper was used as the base material for the support of Example 5.

COMPARATIVE EXAMPLE 1 A double-woven plastic wire (LL400, Nippon Falcon Japan) was used, using bleached hardwood kraft pulp beaten to 340 ml at Canadian standard freeness (csf) and bleached softwood pulp beaten to 350 ml. The base paper was manufactured in the same manner as in Example 1 except that the product was manufactured by the company. The basis weight of the obtained support base material is 150 g / m.
² and the density was 1.02 g / cm ³ . The weight average fiber length of the cellulose fibers in the head box was 0.
It was 7 mm. This base paper was used as the base material for the support of Comparative Example 1.

Comparative Example 2 The same procedure as in Comparative Example 1 was used except that the bleached hardwood sulfite pulp beaten to 350 ml at Canadian standard freeness (csf) was used, and the basis weight was 150 g / m ² and the density was 1.0.
A base paper of ³ g / cm ³ was obtained. The weight average fiber length of the cellulose fibers in the head box was 0.8 mm. This base paper was used as the base material for the support of Comparative Example 2.

Comparative Example 3 A Fourdrinier paper machine using double woven plastic wire (LL400, manufactured by Nippon Falcon Co., Ltd.) using a bleached hardwood sulphite pulp beaten to 350 ml at Canadian standard freeness (csf). The same method as in Example 1 except that the paper is made into paper, the basis weight is 150 g / m ² , and the density is 1.0.
A base paper of ³ g / cm ³ was obtained. The weight average fiber length of the cellulose fibers in the head box was 0.8 mm. This base paper was used as the base material for the support of Comparative Example 3.

Comparative Example 4 All procedures were the same as in Comparative Example 1 except that a hardwood bleached kraft pulp beaten to 360 ml at Canadian standard freeness (csf) and a softwood bleached pulp beaten to 380 ml were used. A base paper with m ² and a density of 0.99 g / cm ³ was obtained. The weight average fiber length of the cellulose fibers in the head box was 0.9 mm. This base paper was used as the base material for the support of Comparative Example 4.

Comparative Example 5 The same procedure as in Comparative Example 1 was repeated except that the bleached hardwood sulfite pulp beaten to 380 ml at Canadian standard freeness (csf) was used, and the basis weight was 150 g / m ² and the density was 0.
A base paper of 99 g / cm ³ was obtained. The weight average fiber length of the cellulose fibers in the head box was 1.0 mm. This base paper was used as the base material for the support of Comparative Example 5.

Comparative Example 6 The same procedure as in Comparative Example 1 was repeated except that the hardwood bleached kraft pulp beaten to 380 ml and the softwood bleached pulp beaten to 390 ml at the Canadian standard freeness (csf) were used. A base paper with m ² and a density of 0.99 g / cm ³ was obtained. The weight average fiber length of the cellulose fibers in the head box was 1.1 mm. This base paper was used as the base material for the support of Comparative Example 6.

Comparative Example 7 The same procedure as in Comparative Example 5 was repeated except that the paper was made using a Fourdrinier paper machine using a double-woven plastic wire (LL400, manufactured by Nippon Falcon Co., Ltd.), and the basis weight was 150 g / m ^2. ,
A base paper having a density of 1.01 g / cm ³ was obtained. The weight average fiber length of the cellulose fibers in the head box is 1.
It was 0 mm. This base paper was used as the base material for the support of Comparative Example 7.

Next, on the front and back surfaces of the base materials for the supports of Examples 1 to 5 and Comparative Examples 1 to 7, the coating amount of the polyolefin resin composition having the following composition was 10 g / m ^{2 on} both the front and back surfaces. A melt-extruded laminator was used to coat and produce the support. Subsequently, an image receiving layer coating liquid having the following composition was provided using an air knife coater so that the dry coating amount was 6 g / m ^2, to obtain an image receiving sheet for thermal transfer. [Blending of polyolefin resin composition] Low-density polyethylene 70 parts High-density polyethylene 15 parts Anatase type titanium dioxide 14 parts Ultramarine 1 part [Blending liquid for image-receiving layer] Polyester emulsion 60 parts Polyethylene emulsion 10 parts Colloidal silica 20 parts Amino-modified silicone Emulsion 5 parts Surfactant 4 parts Crosslinking agent 1 part

[Evaluation Method] (1) Wire Standard Deviation, Fiber Dispersion Standard Deviation For the support base materials of Examples 1-5 and Comparative Examples 1-7, a soft X-ray generator (CMR, manufactured by Softex Co.) A soft X-ray radiograph was photographed by using an image analysis device (Luzex 5000X) under the condition that one pixel is 0.1 mm square, and the H. The standard deviation of the mass fluctuation derived from the wire mark and the standard deviation of the mass fluctuation derived from the dispersion of the fibers were determined by the method of PRAST et al. Incidentally, with respect to these support base materials, fluctuations in the amount of transmitted laser light were also measured, but no correlation was found with the fluctuations in mass measured using soft X-ray photography. (2) Dot reproducibility and density unevenness of transferred image After the thermal transfer image-receiving sheets produced using the base materials for the supports of Examples 1 to 5 and Comparative Examples 1 to 7 were left at 45 ° C for 3 days, the ink donor was used. The sheets were overlapped and printed with a sublimation thermal transfer printer (S3600-30, manufactured by Mitsubishi Electric). Regarding the dot reproducibility of the obtained transferred image, by visual evaluation, good results were obtained without any missing dots, Δ was evaluated with slight missing dots, and × was used with many missing dots. Regarding the density unevenness of the transferred image,
By visual evaluation, the case where there was no density unevenness was evaluated as ◯, the case where slight density unevenness occurred was evaluated as Δ, and the case where severe density unevenness occurred was evaluated as x. The evaluation results are summarized in Table 1.

[0041]

[Table 1]

[Evaluation] From the results shown in Table 1, in Examples 1 to 5, the standard deviation of the mass fluctuation derived from the wire mark of the base material for the support was 1.0 g / m ² or less, and the dispersion of the fibers. Since the coefficient of mass variation derived from was less than 4.0 g / m ² , a transferred image without missing dots and uneven density was obtained. In Comparative Examples 1 to 3, dot variation was observed because the mass variation due to the wire mark was large. Comparative Example 4 ~
In No. 6, since the mass variation due to the dispersion of the fibers was large, uneven density was observed. In Comparative Example 7, the quality of the transferred image was remarkably poor because the mass variation due to the wire marks and the dispersion of the fibers were both large.

[0043]

INDUSTRIAL APPLICABILITY According to the present invention, in an image-receiving sheet for thermal transfer having an image-receiving layer provided on a support, fine scale mass variations and fibers due to the wire marks of the support-forming base material constituting the support are provided. By suppressing the standard deviation of the large-scale mass fluctuation caused by the dispersion of No. 1 to be small, it is possible to obtain an image receiving sheet for thermal transfer having no missing dots in the transferred image and uneven density.

Claims (2)

[Claims] 1. A thermal transfer image-receiving sheet in which at least one of the supports is provided with an image-receiving layer for receiving a dye which migrates from a thermal transfer medium by heat melting or sublimation upon heating, and a base material for the support constituting the support. However, the standard deviation of mass variation due to the wire mark is 1.0 g / m ² or less,
Moreover, the standard deviation of the mass variation due to the dispersion of the fibers is 4.0.
An image-receiving sheet for thermal transfer, characterized by comprising a base paper having a weight of not more than g / m ² . 2. An image-receiving sheet for thermal transfer, wherein the support is a resin-coated paper obtained by coating a support base material with a polyolefin resin.