JP2000044841A - Powder coating coated sheet and powder coating composition therefor - Google Patents

Abstract

(57) Abstract: A method for producing a white powder coating composition containing a fluorescent whitening agent and having an enhanced whiteness, and a sublimation dye thermal transfer image receiving using the white powder coating composition. An object of the present invention is to provide a method for producing a powder coating sheet having high whiteness, which can be suitably used as a sheet or an image receiving sheet for inkjet recording. The method for producing a white powder coating composition for a powder coating sheet according to the present invention comprises a white pigment and a softening point of 15 or more.
In a thermogravimetric analysis, a thermoplastic resin having a melting point of 150 ° C. or higher and a fluorescent whitening agent 0.1 to 2.5% by weight which does not lose weight at a temperature of 150 ° C. or lower is mixed with a thermoplastic resin of 0 ° C. or lower.
The method is characterized in that the thermoplastic resin is melted by heating to a temperature of 180 ° C., kneaded together with the white pigment and the fluorescent whitening agent, cooled, pulverized, and classified into an average particle diameter of 5 to 30 μm. The method for producing a powder coating sheet according to the present invention is a heating roll in which the white powder coating composition obtained as described above is dry-coated on a substrate and has a temperature in the range of 150 to 200 ° C. , And are heated and melted and fixed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a powder coating composition containing a fluorescent whitening agent and having high brightness and saturation, preferably
A method for producing a white powder coating composition having a visually high whiteness, and a recording containing a fluorescent whitening agent, having a high brightness and a high chroma, preferably having a high visual whiteness and therefore having a clear contrast. The present invention relates to a method for producing a powder coating coated sheet which can be suitably used as a sublimable dye thermal transfer image receiving sheet for giving an image or an image receiving sheet for ink jet recording.

[0002]

2. Description of the Related Art Conventionally, various recording systems are known. In recent years, a sublimable dye recording system in which an image is thermally transferred to an image receiving sheet using a sublimable dye,
2. Description of the Related Art An ink jet recording method of ejecting ink toward an image receiving paper, attaching the ink, and recording the ink has been widely used.

A recording method for thermally transferring a sublimable dye is, for example, a thermal transfer sheet (also referred to as an ink sheet or an ink film, hereinafter referred to as an ink sheet or ink film) in which a sublimable dye layer is formed on a suitable support such as a polyethylene terephthalate film. Ink sheet) is prepared, and separately, a thermal transfer recording image receiving paper having a receiving layer for receiving the dye on its surface is prepared, and the surface of the ink sheet on the dye layer side is placed on the receiving layer side of the image receiving paper. The ink sheet is heated according to the image information by a heat-sensitive means such as a thermal head, and the dye is transferred to the receiving layer of the image receiving paper in accordance with the image information. The image is thermally transferred from the printer to the image receiving paper for thermal transfer recording.

In such a sublimation dye thermal transfer recording system, conventionally, an image receiving paper for thermal transfer recording has a receiving layer comprising a resin layer in which a dye of an ink sheet can be diffused or transferred by heat on an appropriate substrate. And a plurality of resin layers composed of a release layer composed of a resin layer for preventing fusion between the receiving layer and the ink sheet during heating, which are manufactured by sequentially laminating a plurality of resin layers by a wet coating method. ing.

That is, in the conventional image receiving paper for sublimation dye thermal transfer recording, a solution containing the resin constituting the receiving layer as described above is applied on a substrate and dried to form a receiving layer. A resin layer for forming a release layer is applied thereon,
It is manufactured by drying to form a release layer, and thus separating and laminating a plurality of resin layers for each function. If necessary, an undercoat layer or an intermediate layer may be formed between the base sheet and the receiving layer. Therefore, such a conventional image-receiving paper for sublimable dye thermal transfer recording includes a multi-stage wet process, and its manufacturing process is complicated, and thus the manufacturing cost is high.

[0006] On the other hand, an ink jet recording system is also well known. Conventionally, an image receiving paper used for ink jet recording is manufactured by wet-coating a solution containing a resin, a pigment, and other additives on a base material and drying the solution to form a resin layer. That is, this resin layer in the ink-jet recording image receiving paper is composed of a resin layer containing a pigment in order to secure the absorbency and the color-forming property of the aqueous ink-jet ink. It is used only when it is water-soluble or water-swellable.

As described above, a high-quality recorded image can be obtained for the first time by using a dedicated image receiving paper regardless of whether the thermal transfer recording is performed by the sublimable dye or the inkjet recording.

However, from the viewpoint of the production, such a dedicated image receiving paper is formed by wet coating a resin or other additives on a base material to form a receptor layer. At the time of removal, consideration for the environment is required, and the resin used is limited as described above. Therefore, the obtained image receiving paper is expensive due to the large number of manufacturing steps and the use of organic solvents. It is.

As described above, in conventional sublimation dye thermal transfer recording or ink jet recording, a special dedicated image receiving paper is required to obtain a high quality recorded image, and ordinary plain paper is used. In such a case, an intended high-quality recorded image cannot be obtained.

Therefore, the present inventors have already disclosed in Japanese Patent Laid-Open No.
In JP-A-112974 and JP-A-8-112974, a powder coating composition containing a white colorant is dry-coated on a substrate, heated and melted and fixed to produce a sublimable dye thermal transfer image-receiving sheet. Suggest a way. However, blending a white pigment such as titanium dioxide in the powder coating composition and making it only white makes the resulting image-receiving sheet insufficient in whiteness, making it difficult to obtain a clear color image with regret. However, there is a problem that the whiteness of the receiving layer is liable to decrease with time, and an image receiving sheet having a high whiteness has conventionally been required. Here, high whiteness means visually high whiteness, which means pale white.

As described above, for a sublimation dye thermal transfer image-receiving sheet which forms a receptor layer by applying a solution containing a resin constituting the receptor layer on a substrate and drying, a fluorescent whitening agent is added to the receptor layer. (Fluorescent white dye) has already been proposed in JP-A-61-237693 to increase the whiteness. In the case of manufacturing an image receiving sheet by such a wet method, in the manufacturing process, the optical brightener used is not melted by heating or causes a structural change by heating, and a small amount thereof is compounded. Accordingly, it is possible to obtain an image receiving sheet whose whiteness is increased by the fluorescent whitening agent.

However, for the production of a white powder coating composition,
Mixing a fluorescent whitening agent with a thermoplastic resin and a pigment and including a step of melt-kneading the same. In this process, most of the fluorescent whitening agent melts or undergoes a structural change due to heating, resulting in whitening. Since the effect is lost, the resulting powder coating composition does not improve whiteness at all, and of course, even with such a powder coating composition, a powder coating composition sheet excellent in whiteness, especially However, an image receiving sheet for sublimation dye thermal transfer recording or an image receiving sheet for ink jet recording cannot be obtained.

[0013]

SUMMARY OF THE INVENTION The present inventors have investigated the production of powder coating compositions by adding pigments, especially
The melting point is 150 ° C. or higher together with the chromatic pigment, and
In thermogravimetric analysis, a fluorescent whitening agent that does not lose weight at a temperature of 150 ° C. or less is mixed with a thermoplastic resin, the mixture is heated, the thermoplastic resin is melted, and these are kneaded to form a resin. After dispersing the pigment and the optical brightener,
By cooling, pulverizing and classifying, it is possible to obtain a powder coating composition with increased lightness and saturation, and further,
By dry-coating such a powder coating composition on a substrate, heat-melting, and fixing, it has been found that a powder coating sheet with increased lightness and saturation can be obtained, and in particular, When a white pigment is used as the pigment, a powder coating composition having an increased visual whiteness can be obtained. By using such a powder coating composition, a visual white color can be obtained. The present inventors have found that a powder coating sheet having an increased degree can be obtained, and have reached the present invention.

Further, according to the present inventors, as a result of intensive studies on thermal transfer of a sublimable dye by dry coating of a powder coating composition and production of an image receiving sheet by ink jet recording, not by wet coating, The powder coating composition is mixed with inorganic fine particles at a predetermined ratio to form a powder mixture, which is dry-coated on a substrate, melted by heating, and fixed to form a single-layer receiving layer. In the meantime, it has been found that a sublimable dye thermal transfer image-receiving sheet or an ink-jet recording image-receiving sheet capable of obtaining a high-quality recorded image can be obtained, and the present invention has been accomplished.

[0015]

The process for producing a powder coating composition for a powder coating sheet according to the present invention comprises a pigment, a thermoplastic resin having a softening point of 150 ° C. or lower, and a melting point of 150 ° C. or higher. At the same time, in thermogravimetric analysis, 0.1 to 2.5% by weight of a fluorescent whitening agent that does not lose weight at a temperature of 150 ° C. or less is heated to a temperature of 150 to 180 ° C. to melt the thermoplastic resin. After kneading with the pigment and the fluorescent whitening agent, the mixture is cooled, pulverized, and classified into an average particle diameter of 5 to 30 μm.

In the method for producing a powder coating sheet according to the present invention, the powder coating composition obtained as described above is dry-coated on a substrate and has a temperature in the range of 150 to 200 ° C. It is characterized in that it is guided to a heating roll, heated and melted, and fixed.

A preferred method for producing a powder coating sheet according to the present invention is to mix the powder coating composition obtained as described above with 0.5 to 12% by weight of inorganic fine particles having an average particle diameter of 1 to 1 μm. The powder mixture is dry-coated on a substrate, guided to a heating roll having a temperature in the range of 150 to 200 ° C., melted by heating, and fixed.

In particular, according to the present invention, as the pigment,
By using a chromatic pigment, it is possible to obtain a powder coating composition and a powder coating sheet for a powder coating sheet with increased lightness and saturation, and on the other hand, as the pigment, a white pigment By using, a white powder coating composition for a powder coating sheet and a white powder coating sheet with an increased visual whiteness can be obtained.

Further, according to the present invention, by using hydrophilic inorganic fine particles as the inorganic fine particles, it is possible to obtain a powder coating sheet which can be used as a high quality image receiving sheet for ink jet recording. , On the other hand,
By using hydrophobic inorganic fine particles as the inorganic fine particles, it is possible to obtain a powder coating sheet which can be used as an image receiving sheet for high quality sublimable dye thermal transfer recording.

Thus, according to the present invention, by using a white pigment as the above-mentioned pigment and using hydrophilic inorganic fine particles, it is possible to obtain a high-quality image-receiving sheet for inkjet recording which forms a clear contrast image. On the other hand, by using hydrophobic inorganic fine particles as the inorganic fine particles, it is possible to obtain a high-quality image-receiving sheet for sublimation dye thermal transfer recording which forms a clear image.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION In a preferred embodiment of the present invention, a white powder coating composition having a high visual whiteness is obtained by using a white pigment as a pigment, and a clear contrast image is formed using the white powder coating composition. Since the present invention is intended to obtain a high-quality image-receiving sheet for ink jet recording or an image-receiving sheet for sublimable dye thermal transfer recording to be formed, the present invention will be specifically described below with respect to this aspect. However, in the following, in place of the white pigment, by using various chromatic pigments, it is possible to obtain a powder coating composition with increased brightness and saturation,
It will be apparent from the following description that a powder paint coated sheet having increased lightness and saturation can be obtained by using the same.

First, the production of the white powder coating composition for a powder coating sheet according to the present invention will be described.

The white powder coating composition for a powder coating sheet according to the present invention comprises a white pigment, a thermoplastic resin having a softening point of 150 ° C. or lower, a melting point of 150 ° C. or higher, and a thermogravimetric analysis. A brightening agent that does not lose weight at a temperature of 150 ° C. or less and 0.1 to 2.5% by weight is heated to a temperature of 150 to 180 ° C. to melt the thermoplastic resin, After kneading with whitening agent, cool, pulverize,
It can be obtained by classifying into an average particle size of 5 to 30 μm.

The white pigment is used to give a base material a white ground color. As the white pigment, for example, titanium oxide or zinc oxide is preferably used, but is not limited thereto. The white pigment is used in the powder coating composition in an amount of usually 1 to 50% by weight, preferably 5 to 40% by weight.

First, the thermoplastic resin has a role as a binder resin for collecting various components of the powder coating composition into powder. Second, as described below, whether the powder coating composition is used for manufacturing an ink-jet recording image-receiving sheet,
Alternatively, they have different roles depending on whether they are used for producing a sublimable dye thermal transfer image-receiving sheet.

Examples of such a resin include a saturated polyester resin, a polyamide resin, a poly (meth) acrylate resin, a polyurethane resin, a polyvinyl alcohol resin, a polyvinyl acetal resin, a vinyl chloride resin, a vinyl acetate resin, and a vinyl chloride resin. Styrene resins such as vinyl acetate copolymer resin, vinylidene chloride resin, polystyrene resin, styrene / acryl copolymer resin, styrene / butadiene copolymer resin, polyethylene resin, ethylene / vinyl acetate copolymer resin, polyethylene resin, cellulose And the like. These resins are used alone or as a mixture of two or more.

In the present invention, when the white powder coating composition is used for producing a sublimable dye thermal transfer image-receiving sheet, the resin may be a saturated polyester resin or styrene.
An acrylic copolymer resin or a mixture thereof is preferably used. When the white powder coating composition is used for producing a sublimable dye thermal transfer image-receiving sheet, the resin is not particularly limited.

In the production of the white powder coating composition according to the present invention, a fluorescent whitening agent which has a melting point of 150 ° C. or more and does not lose weight at a temperature of 150 ° C. or less in thermogravimetric analysis is used. Here, in the present invention, the melting point of the optical brightener is determined by a differential scanning calorimetry (DSC method). Thermogravimetric analysis (TG) is a type of analysis method that continuously measures the change in weight of a sample while heating the sample (edited by Toshiyuki Shono et al., “Introductory Instrumental Analysis Chemistry” (1992).
6th year, published by Sankyo Publishing Co., Ltd.) p. 258). Therefore, in thermogravimetric analysis, a fluorescent whitening agent that does not lose weight at a temperature of 150 ° C. or less means that a flat TG curve is obtained at a temperature of 150 ° C. or less when a sample is heated at a constant rate in thermogravimetric analysis. Refers to the fluorescent whitening agent to be drawn.

In the present invention, the optical brightener used is:
The chemical structure is not subject to any restrictions, but it must satisfy the above thermal conditions. Specific examples of such a fluorescent whitening agent include, for example, a stilbene fluorescent agent (manufactured by Kasano Kosan, melting point 189.3 ° C.), Ubitex OB (manufactured by Nippon Ciba Geigy, melting point 174.4).
° C).

Further, in the present invention, in order to produce a powder-coated sheet as a sublimable dye thermal transfer image-receiving sheet or an ink-jet recording image-receiving sheet, the powder coating composition must have an average particle diameter of 5 to 30 μm. In order to obtain such a powder coating composition, it is preferable to uniformly disperse a fluorescent whitening agent together with a white pigment in a molten thermoplastic resin to obtain the image receiving sheet having high whiteness. To
The fluorescent whitening agent contains 50% of particles having a particle diameter of 5 μm or less.
And the number of particles having a particle diameter of 10.6 μm or less is 90
% Or more, and more preferably such an optical brightener is used in the range of 0.1 to 2.5% by weight.

When the amount of the fluorescent whitening agent is less than 0.1% by weight based on the powder coating composition, the whiteness of the obtained powder coating composition or powder coating sheet is increased. On the other hand, when it exceeds 2.5% by weight, the powder coating composition itself becomes yellowish due to the tint of the fluorescent whitening agent, that is, yellowish, and the visual whiteness is reduced. Can't increase.

According to the present invention, after the powder coating composition is dry-coated on the surface of the base material, it is heated and melted, and the above-mentioned thermoplastic resin and the white resin are used so as not to cause offset when being fixed. Along with pigments and optical brighteners, if necessary,
An offset preventing agent may be used. As the anti-offset agent, usually, various waxes having a melting point in the range of 50 to 150 ° C. are preferably used. Specific examples include paraffin wax, polyolefin wax such as polyethylene and polypropylene, fatty acid metal salts, fatty acid esters, higher fatty acids, higher alcohols, and the like. Such an anti-offset agent is usually added to the powder coating composition in an amount of 0.1 to 20% by weight, preferably 0.5 to 1% by weight.
It is used in the range of 0% by weight.

The powder coating composition according to the present invention is prepared by mixing the above-mentioned thermoplastic resin, colorant and fluorescent whitening agent together with other necessary additives, if necessary, and
It can be obtained by melt-kneading at a temperature in the range of 180 ° C. for several minutes, usually about 3 to 5 minutes, cooling, and then classifying into an average particle diameter of 5 to 30 μm.

According to the present invention, by selecting and using a fluorescent whitening agent having the above-mentioned thermal characteristics, it is heated to a temperature of 150 to 180 ° C. together with a thermoplastic resin and a white pigment, and is melt-kneaded. Even so, the fluorescent whitening agent does not lose the whitening effect during that time, and effectively improves the whiteness of the obtained powder coating composition.

The powder coating sheet according to the present invention is obtained by dry-coating such a white powder coating composition on a substrate,
It can be obtained by introducing a heating roll having a temperature in the range of 0 to 200 ° C., heating and melting and fixing, and the fluorescent whitening agent is fixed during fixing on the substrate of the powder coating composition. Thus, a powder coating sheet having high whiteness can be obtained without losing the whitening effect.

According to the present invention, such a white powder coating composition is preferably mixed with inorganic fine particles having an average particle diameter of 1 nm to 1 μm, preferably 2 to 50 nm to form a powder mixture. Dry-coated on a substrate, heated and melted, fixed, the particles of the powder coating composition are separated from each other by a substantially continuous film composed of the inorganic fine particles, separated, and a gap therebetween. It can be obtained by forming a resin layer having on a base material.

In the present invention, the substrate is usually
Paper, synthetic paper, synthetic resin sheet and the like are preferably used.
Examples of the synthetic resin sheet include sheets made of polyester, polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate, polycarbonate, polyamide, and the like. As a synthetic paper, for example, a polyolefin resin or other synthetic resin is used as a resin component, and a required inorganic filler or the like is mixed with the resin component.
Examples include those obtained by extrusion. In particular, by using paper as the base material, the powder-coated sheet according to the present invention, that is, the ink-jet recording image receiving sheet or the sublimable dye thermal transfer image receiving sheet can be manufactured at low cost.

In the present invention, the thickness of the resin layer comprising the above powder mixture is usually in the range of 1 to 100 μm,
Preferably, it is in the range of 2 to 80 μm, particularly preferably in the range of 5 to 50 μm.

FIG. 1 schematically shows a cross section of such a powder coating sheet according to the present invention. On the substrate 11,
The individual powder coating composition particles 12 are covered with a film 14 in which inorganic fine particles 13 are substantially connected and are isolated from each other to form a resin layer 15 having an interval or a gap therebetween. Reference numeral 13 is partially exposed on the surface of the resin layer 15.

In order to form a resin layer having such a specific structure, it is necessary to mix inorganic fine particles at a required ratio with respect to the powder coating composition. According to the present invention, the proportion of the inorganic fine particles is usually 1 to 12% by weight in the powder mixture comprising the powder coating composition and the inorganic fine particles.
, Preferably in the range of 3 to 10% by weight, most preferably in the range of 5 to 8% by weight. When the blending ratio of the inorganic fine particles is too small, the inorganic fine particles are substantially continuous in a film form, coat the individual powder coating particles, isolate and separate each other, and form a resin layer having voids therebetween. Cannot be formed. On the other hand, when the amount is too large, the fixing property of the receiving layer to the base material is poor. For example, when the base material is bent, the receiving layer peels off from the base material.

According to the present invention, the inorganic fine particles are selected depending on whether the obtained powder coating sheet is used for a sublimation dye thermal transfer image receiving sheet or an image receiving paper for ink jet recording. That is, when the obtained powder paint coated sheet is used for a sublimable dye thermal transfer image receiving sheet,
As the inorganic fine particles, hydrophobic ones are used. On the other hand,
When the obtained powder coating sheet is used for an image receiving paper for inkjet recording, hydrophilic inorganic fine particles are used. However, in order to adjust the adsorptivity of the aqueous inkjet ink in the ink receiving layer, hydrophilic inorganic fine particles and hydrophobic inorganic fine particles can be used in combination, if necessary. Both such hydrophilic inorganic fine particles and hydrophobic inorganic fine particles are preferably inorganic oxide fine particles.

Such inorganic oxide fine particles can be easily obtained as a commercial product. Commercially available hydrophilic inorganic oxide fine particles include, for example, Aerosil (registered trademark) 50, 9 which is anhydrous silica manufactured by Nippon Aerosil Co., Ltd.
0G, 130,200,200V, 200CF, 200
FAD, 300, 300CF, 380, OX50, TT
600, MOX80, MOX170, COK84, etc.
Aluminum oxide C, titanium dioxide P25, etc., Carplex (registered trademark) silica BS- manufactured by Shionogi & Co., Ltd.
304F, etc., and anhydrous silicas S13, V15, N20, T30, T30 manufactured by Wacker Chemicals East Asia.
40 and the like.

In addition to the inorganic oxide, for example, calcium carbonate, barium sulfate or the like is used as hydrophilic inorganic fine particles.

On the other hand, commercially available hydrophobic inorganic oxide fine particles include, for example, Aerosil R972, R972V, and R972 which are anhydrous silica manufactured by Nippon Aerosil Co., Ltd.
CF, R974, R202, R805, R812S, titanium dioxide T805, RX200, RY200, etc., and anhydrous silica H1 manufactured by Wacker Chemicals East Asia
5, H20, H30, H2000, H2000 / 4, H
3004, H2015EP, H2050EP and the like.

As described above, the powder coating paper according to the present invention is coated with particles of the powder coating composition by a substantially continuous film composed of inorganic fine particles, isolated from each other, and separated from each other. Having a resin layer,
As described above, not only the inorganic fine particles are exposed in the form of a film on the surface of the resin layer, but also there is usually an interval of about 1 to 200 nm between the particles of the powder coating composition. Some gaps exist between the powder coating composition particles.

Thus, the powder-coated sheet according to the present invention can be suitably used as an image-receiving sheet for ink-jet recording and as a sublimable dye thermal transfer image-receiving sheet.

That is, when such a powder coating sheet according to the present invention is used as a sublimation dye thermal transfer image-receiving sheet, the powder coating composition particles that receive the dye are each coated with a film composed of inorganic fine particles. Since it is separated, it only has a single-layer receiving layer composed of powder coating composition particles on the base material, but the receiving layer itself has already excellent releasability from the ink sheet. Have.

On the other hand, when the powder coating sheet according to the present invention is used as an image receiving sheet for ink jet recording,
If the aqueous inkjet ink adheres to the ink, the ink penetrates into the receiving layer along the film composed of the hydrophilic inorganic fine particles between the powder coating composition particles, and is quickly adsorbed and captured by the inorganic fine particles. Therefore, a high-density and accurate ink-jet recorded image can be obtained.

In order to form a resin layer comprising the powder coating composition particles as described above on a substrate, a powder mixture of the powder coating composition and inorganic fine particles is dry-coated on the substrate, This is melted by heating and fixed. As described above, the thickness of the resin layer is preferably in the range of 2 to 80 μm.
It is preferably in the range of 0 μm.

In the present invention, in order to dry-coat a powder coating composition containing inorganic fine particles on a substrate, for example, electrostatic coating such as electrostatic spraying or electrostatic immersion, spraying, spraying, etc. Powder coating such as coating method, dispersion method, powder melt lamination method, dusting method, cascade method, magnetic brush developing method,
Electrophotographic methods such as a powder cloud method, an open chamber method, a liquid developing method, a fur developing method, a printing developing method, and a developing method by electrostatic induction can be used.

Among these dry coatings, in the present invention, for example, an electrostatic spray method can be preferably used. This electrostatic spraying method is a kind of powder coating, and specifically, a mixture of a fine powder coating composition and inorganic fine particles (hereinafter referred to as a powder mixture) at the tip of a spray gun is air. And a negative high voltage (for example,
-50 to -90 kV) to apply a negative charge to the powder mixture and, along with a grounded electrode to the back surface of the substrate,
Thus, the negatively charged powder mixture is carried to the substrate and electrostatically deposited by the electric field present between the spray gun and the grounded electrode.

FIG. 2 shows a preferred embodiment of the method of the present invention using such an electrostatic spray method. That is, roll 2
A continuous long substrate (for example, plain paper) 22 rewound from 1 is guided into a booth 24 by a conveyor belt 23, where the powder mixture is electrostatically sprayed, as described later. Is dry-coated, heated and melted by a fixing roll 25, fixed, and then wound around a roll or cut as appropriate. The conveyor belt 23 is grounded on the back side along the base material that the conveyor belt 23 conveys (ie,
(Positive electrode) 26. The powder mixture is stored in storage tank 27
From compressed air to the spray gun 28,
A high negative voltage is applied by a DC power supply 29 to a needle electrode (not shown) incorporated at the tip of the spray gun, and the powder mixture is negatively charged. Thus, the powder mixture is carried to and adheres to the base paper by the electric field present between the spray gun and the electrodes along the substrate on the conveyor belt. In this way, the substrate on which the powder mixture is dry-coated is guided to the fixing roll 25, where the powder mixture is heated and melted, fixed on the substrate, and a resin layer is formed. The powder coating paper 30 according to the present invention can be obtained.

Therefore, according to such an electrostatic spraying method, not only a resin layer is formed on the entire surface of the base material, but also, if necessary, only a part of the base material or a required portion can be easily formed. A resin layer can be formed.

Thus, according to the present invention, despite the step of heating and melting the powder mixture on a substrate with a fixing roll at 150 to 200 ° C., In the meantime, the function is not lost, and thus a powder paint coated sheet having high whiteness can be obtained.

The powder coating sheet according to the present invention has CI
E (International Commission on Illumination) chromaticity diagram (white point x = y = 0.33
33. ), X ≦ 0.3110, y ≦
A powder paint coated sheet having a chromaticity coordinate of 0.3300 and having a visually high whiteness (hence, visually pale) can be obtained. The original white point is, as described above,
It has a yellow tint.

[0056]

As described above, according to the method of the present invention,
In the thermogravimetric analysis, a fluorescent whitening agent having a melting point of 150 ° C. or higher and not losing weight at a temperature of 150 ° C. or lower is selected, and this is mixed with a thermoplastic resin and a pigment at 150 to 18%.
By heating to a temperature of 0 ° C., melt-kneading, cooling, pulverizing, and classifying to an average particle diameter of 5 to 30 μm,
The visual whiteness of the obtained white powder coating composition can be effectively improved without structural change of the fluorescent whitening agent.

Then, the white powder coating composition is dry-coated on a substrate, guided to a heating roll having a temperature in the range of 150 to 200 ° C., melted by heating, and fixed to obtain the above-mentioned composition. It is possible to obtain a powder paint coated sheet maintaining the whiteness of the powder paint composition.

In particular, according to the present invention, the above-mentioned white powder coating composition is blended with inorganic fine particles having an average particle diameter of 1 to 1 μm to form a powder mixture. The powder coating composition particles are covered by a substantially continuous film of such inorganic fine particles by being guided to a heating roll having a temperature in the range of ~ 200 ° C, heated and melted and fixed, and Isolated, separated, it is possible to obtain a powder coating sheet having a resin layer composed of powder coating composition particles having an interval between the particles of the individual powder coating composition on a substrate, Due to such a structure, such a powder coating sheet can form a high-density accurate image even when used as an ink-jet recording image-receiving sheet or as a sublimation dye thermal transfer image-receiving sheet. It can be.

[0059]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited by these examples. FIG. 3 shows a TG curve of a stilbene fluorescent agent manufactured by Kasano Kosan used in the following examples, and FIG. 4 shows a TG curve of Ubitex OB manufactured by Ciba-Geigy Japan. As described above, a flat TG curve is drawn at a temperature of 150 ° C. or less, and there is no weight loss.

FIG. 5 shows the TG curve of White Flower B manufactured by Sumika Color Co., Ltd. used in the following comparative examples. T
The G curve is shown in FIG. White Flower B is 150
It draws a flat TG curve at a temperature below ℃,
There is no weight loss, but the melting point is 74.8 ° C. Mike Fall BN conc. Has a melting point of 88.1 ° C., and its TG curve shows a T
The G curve is curved and there is a weight loss.

In the following, the CIE chromaticity coordinates (x, y) of the image receiving paper are represented by a color difference meter ZE-
It is a value obtained by measuring using 2000 and taking an average value of five measured values.

Example 1 (Preparation of Powder Coating Composition and Powder Mixture) 70 parts by weight of a saturated polyester resin (FC-714 manufactured by Mitsubishi Rayon Co., Ltd.) and a white pigment (titanium oxide manufactured by Ishihara Sangyo Co., Ltd. A220 ”) 24.9 parts by weight and a fluorescent whitening agent (a stilbene fluorescent agent manufactured by Kasano Kosan, melting point: 189.3 ° C., number of particles having a particle diameter of 5 μm or less: 72.95%, number of particles having a particle diameter of 10.6 μm or less) 0.1 parts by weight (95.0%, average particle size: 14.88 μm) was melt-kneaded at 150 to 160 ° C. for 3 to 5 minutes by a biaxial melt kneader. After cooling, the obtained kneaded product was pulverized and classified to obtain a white powder coating composition having an average particle size of 11.0 μm. 95 parts by weight of this white powder coating composition was added to hydrophobic anhydrous silica (Hacker Chemicals manufactured by Wacker Chemicals East Asia).
5 parts by weight (2000/4, average particle size 16 nm) were mixed to obtain a white powder mixture for dry coating by an electrostatic spray method.

(Manufacture of Sublimation Dye Thermal Transfer Image Receiving Paper) The above white powder mixture is adhered to the entire surface of a commercially available plain paper using a commercially available electrostatic spray device, and then heated, melted and fixed. Thus, a sublimable dye thermal transfer image-receiving paper having a receiving layer having a thickness of 20 μm was obtained. The whiteness of the image receiving paper was evaluated by chromaticity evaluation of CIE chromaticity coordinates. In addition, a sensory evaluation of visual whiteness was performed. Table 1 shows the results.

(Thermal Transfer Recording from Ink Sheet) The sublimation dye thermal transfer printer (Color Paint 1835PSJ, manufactured by Seiko Instruments Inc.) was used on the image receiving paper thus obtained. When the sublimable dye was thermally transferred, a high-density thermal transfer image could be obtained. Further, at the time of this thermal transfer, the presence or absence of fusion between the image receiving paper and the ink sheet was examined. Table 1 shows the results.

Example 2 In Example 1, 23.5 parts by weight of a white pigment and a fluorescent whitening agent (Ubitex OB manufactured by Ciba-Geigy Japan, melting point: 174.
At 4 ° C., the number of particles having a particle diameter of 5 μm or less 59.99%, the number of particles having a particle diameter of 10.6 μm or less 90.9%, and the average particle diameter is 1
6.52 μm) A white powder mixture having the composition shown in Table 1 was prepared in the same manner as in Example 1 except that 1.5 parts by weight was used, and this was used to form a 20 μm thick film on a commercially available plain paper. Was formed to obtain a sublimable dye thermal transfer image-receiving paper.

The whiteness of the image receiving paper was evaluated by evaluating the chromaticity of the CIE chromaticity coordinates. In the same manner as in Example 1, visual sensory evaluation of whiteness and presence / absence of fusion at the time of thermal transfer from the ink sheet were examined. Table 1 shows the results.

Comparative Example 1 In Example 1, 24.95 parts by weight of a white pigment and a fluorescent whitening agent (a stilbene fluorescent agent manufactured by Kasano Kosan, melting point 189.3 ° C.) were used.
A white powder mixture having the composition shown in Table 1 was prepared in the same manner as in Example 1 except that 05 parts by weight was used, and a receiving layer having a thickness of 20 μm was formed on commercially available plain paper using the mixture. Thus, a sublimable dye thermal transfer image-receiving paper was obtained.

The whiteness of the image receiving paper was evaluated by chromaticity evaluation of CIE chromaticity coordinates. In the same manner as in Example 1, visual sensory evaluation of whiteness and presence / absence of fusion at the time of thermal transfer from the ink sheet were examined. Table 1 shows the results.

Comparative Example 2 In Example 1, 22.0 parts by weight of a white pigment and a fluorescent whitening agent (Ubitex OB manufactured by Nippon Ciba Geigy, melting point: 174.
4 ° C.) A white powder mixture having the composition shown in Table 1 was prepared in the same manner as in Example 1 except that 3.0 parts by weight was used.
Using this, a receiving layer having a thickness of 20 μm was formed on commercially available plain paper to obtain a sublimable dye thermal transfer image-receiving paper.

The whiteness of the image receiving paper was evaluated by evaluating the chromaticity of CIE chromaticity coordinates. In the same manner as in Example 1, visual sensory evaluation of whiteness and presence / absence of fusion at the time of thermal transfer from the ink sheet were examined. Table 1 shows the results.

Comparative Example 3 In Example 1, 24.0 parts by weight of a white pigment and a fluorescent whitening agent (White Flour B manufactured by Sumika Color Co., Ltd.) were used.
B), melting point 74.8 ° C.) A white powder mixture having the composition shown in Table 1 was prepared in the same manner as in Example 1 except that 1.0 part by weight was used. 20 thickness on plain paper
A sublimation dye thermal transfer image-receiving paper was obtained by forming a μm receiving layer.

The whiteness of the image receiving paper was evaluated by evaluating the chromaticity of the CIE chromaticity coordinates. In the same manner as in Example 1, visual sensory evaluation of whiteness and presence / absence of fusion at the time of thermal transfer from the ink sheet were examined. Table 1 shows the results.

Comparative Example 4 In Example 1, 24.0 parts by weight of a white pigment and a fluorescent whitening agent (Mikefall BNconc.
kephor BN conc.), melting point 88.1 ° C.) A white powder mixture having the composition shown in Table 1 was prepared and used in the same manner as in Example 1 except that 1.0 part by weight was used. A sublimation dye thermal transfer image-receiving paper was obtained by forming a receptor layer having a thickness of 20 μm on a commercially available plain paper.

The whiteness of the image receiving paper was evaluated by evaluating the chromaticity of CIE chromaticity coordinates. In the same manner as in Example 1, visual sensory evaluation of whiteness and presence / absence of fusion at the time of thermal transfer from the ink sheet were examined. Table 1 shows the results.

Comparative Example 5 The procedure of Example 1 was repeated, except that 25.0 parts by weight of a white pigment was used and no fluorescent whitening agent was used.
A white powder mixture having the composition shown in Table 1 was prepared and used to form a receiving layer having a thickness of 20 μm on commercially available plain paper to obtain a sublimable dye thermal transfer image-receiving paper.

The whiteness of the image receiving paper was evaluated by chromaticity evaluation of CIE chromaticity coordinates. In the same manner as in Example 1, visual sensory evaluation of whiteness and presence / absence of fusion at the time of thermal transfer from the ink sheet were examined. Table 1 shows the results.

[0077]

[Table 1]

Example 3 (Preparation of powder coating composition and powder mixture) Styrene / acrylic copolymer resin (CPR-200, Mitsui Chemicals, Inc.)
70 parts by weight, 24.9 parts by weight of white pigment (titanium oxide "Taipek A220" manufactured by Ishihara Sangyo Co., Ltd.) and fluorescent whitening agent (stilbene fluorescent agent manufactured by Kasano Kogyo, melting point: 189.3 ° C.) 0.1
Parts by weight at 150-160 ° C with a twin-screw kneader at 3-5
Melted and kneaded for minutes. After cooling, the obtained kneaded product was pulverized and classified to obtain a white powder coating composition having an average particle size of 11.0 μm. 95 parts by weight of this white powder coating composition was mixed with hydrophilic anhydrous silica (Aerosil 20 manufactured by Nippon Aerosil Co., Ltd.).
(0, average particle diameter: 12 nm) was mixed with 5 parts by weight to obtain a white powder mixture for dry coating by an electrostatic spray method.

(Production of Inkjet Recording Image Receiving Paper) The above white powder mixture was adhered to the entire surface of a commercially available plain paper using a commercially available electrostatic spray device, and then heated, melted and fixed. Thus, an image receiving paper for ink jet recording having a receiving layer having a thickness of 20 μm was obtained. The whiteness of the image receiving paper was evaluated by chromaticity evaluation of CIE chromaticity coordinates. Also,
Sensory evaluation of visual whiteness was performed. Table 2 shows the results.

(Ink-jet recording) When ink-jet recording was performed on the image-receiving paper thus obtained using a commercially available ink-jet printer (manufactured by Epson), a high-quality recorded image could be obtained quickly. Was. In addition, Table 2 shows the results of examining the presence or absence of ink repelling on the image receiving paper during ink jet recording.

Example 4 In Example 3, 23.5 parts by weight of a white pigment and a fluorescent whitening agent (Ubitex OB manufactured by Ciba-Geigy Japan, melting point: 174.
4 ° C.) A white powder mixture having the composition shown in Table 2 was prepared in the same manner as in Example 3 except that 1.5 parts by weight was used.
Using this, a receiving layer having a thickness of 20 μm was formed on a commercially available plain paper to obtain an image receiving paper for ink jet recording.

The whiteness of the image receiving paper was evaluated by chromaticity evaluation of CIE chromaticity coordinates. In the same manner as in Example 3, the visual sensory evaluation of whiteness and the presence or absence of ink repelling on the image receiving paper during ink jet recording were examined. Table 2 shows these results.
Shown in

Comparative Example 6 In Example 3, 24.95 parts by weight of a white pigment and a fluorescent whitening agent (a stilbene fluorescent agent manufactured by Kasano Kosan, melting point 189.3 ° C.) were used.
A white powder mixture having the composition shown in Table 3 was prepared in the same manner as in Example 3 except that 05 parts by weight was used, and a receiving layer having a thickness of 20 μm was formed on commercially available plain paper using this mixture. Thus, an image receiving paper for ink jet recording was obtained.

The whiteness of the image receiving paper was evaluated by chromaticity evaluation of CIE chromaticity coordinates. In the same manner as in Example 3, the visual sensory evaluation of whiteness and the presence or absence of ink repelling on the image receiving paper during ink jet recording were examined. Table 2 shows these results.
Shown in

Comparative Example 7 In Example 3, 22.0 parts by weight of a white pigment and a fluorescent whitening agent (Ubitex OB manufactured by Ciba-Geigy Japan, melting point: 174.
4 ° C.) A white powder mixture having the composition shown in Table 1 was prepared in the same manner as in Example 3 except that 3.0 parts by weight was used.
Using this, a receiving layer having a thickness of 20 μm was formed on a commercially available plain paper to obtain an image receiving paper for ink jet recording.

The whiteness of the image receiving paper was evaluated by evaluating the chromaticity of the CIE chromaticity coordinates. In the same manner as in Example 3, the visual sensory evaluation of whiteness and the presence or absence of ink repelling on the image receiving paper during ink jet recording were examined. Table 2 shows these results.
Shown in

Comparative Example 8 In Example 3, 24.0 parts by weight of a white pigment and a fluorescent whitening agent (white flower B, Sumika Color, melting point 74.8 ° C.)
A white powder mixture having the composition shown in Table 2 was prepared in the same manner as in Example 1 except that 1.0 part by weight was used, and a 20 μm-thick receiving layer was formed on a commercially available plain paper using the mixture. Thus, an image receiving paper for ink jet recording was obtained.

The whiteness of the image receiving paper was evaluated by chromaticity evaluation of CIE chromaticity coordinates. In the same manner as in Example 3, the visual sensory evaluation of whiteness and the presence or absence of ink repelling on the image receiving paper during ink jet recording were examined. Table 2 shows these results.
Shown in

Comparative Example 9 The procedure of Example 3 was repeated except that 24.0 parts by weight of a white pigment and 1.0 of a fluorescent whitening agent (Wykefall BNconc., Melting point: 88.1 ° C.) were used.
Except for using parts by weight, a white powder mixture having the composition shown in Table 2 was prepared in the same manner as in Example 3, and this was used to form a 20 μm-thick receiving layer on commercially available plain paper. Thus, an image receiving paper for ink jet recording was obtained.

The whiteness of the image receiving paper was evaluated by evaluating the chromaticity of CIE chromaticity coordinates. In the same manner as in Example 3, the visual sensory evaluation of whiteness and the presence or absence of ink repelling on the image receiving paper during inkjet recording were examined. Table 2 shows these results.
Shown in

[0091]

[Table 2]

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a preferred example of a powder coating sheet according to the present invention.

FIG. 2 shows an example of an apparatus configuration for manufacturing a powder-coated paper according to the present invention.

FIG. 3 shows a TG curve of an example of an optical brightener that can be used in the present invention.

FIG. 4 shows a TG curve of another example of the optical brightener that can be used in the present invention.

FIG. 5 shows a TG curve of the optical brightener used in Comparative Example.

FIG. 6 shows T of another optical brightener used in the comparative example.
The G curve is shown.

[Explanation of symbols]

11: base material, 12: powder coating composition particles, 13: inorganic fine particles, 14: film composed of inorganic fine particles, 15: resin layer, 2
DESCRIPTION OF SYMBOLS 1 ... Roll, 22 ... Base paper, 23 ... Conveying belt, 24 ... Booth, 25 ... Fixing roll, 26 ... Electrode, 27 ... Powder coating composition storage tank, 28 ... Spray gun, 29 ... DC power supply,
30 ... powder coated paper.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09B 57/00 B41J 3/04 101Y 4J038 C09D 7/12 B41M 5/26 101H F-term (Reference) 2C056 FC06 2H086 BA02 BA31 BA33 BA34 BA41 BA45 2H111 BA03 BA32 BA38 BA53 BA55 BA71 BA74 DA01 4D075 AA09 AA52 AA76 BB29Z DA04 DC27 EA02 EA17 EC11 4H056 DA01 FA02 4J038 CG141 CR071 DD001 DH001 HA216 KA08 KA20 LA06 MA02

Claims (11)

[Claims] 1. A pigment, a thermoplastic resin having a softening point of 150 ° C. or lower, and a fluorescent whitening agent having a melting point of 150 ° C. or higher and having no weight loss at a temperature of 150 ° C. or lower in thermogravimetric analysis. 1 to 2.5% by weight is heated to a temperature of 150 to 180 ° C. to melt the thermoplastic resin, kneaded with the pigment and the fluorescent whitening agent, and then cooled and pulverized to obtain an average particle size of 5%.
A method for producing a powder coating composition for a powder coating sheet, characterized in that the composition is classified to 30 μm. 2. The fluorescent whitening agent according to claim 1, wherein the number of particles having a particle diameter of 5 μm or less is 50% or more, and the number of particles having a particle diameter of 10.6 μm or less is 90% or more. A method for producing a powder coating composition for a powder coating sheet. 3. The method for producing a powder coating composition for a powder coating sheet according to claim 1, wherein the pigment is a white pigment. 4. A pigment, a thermoplastic resin having a softening point of 150 ° C. or lower, and a fluorescent whitening agent having a melting point of 150 ° C. or higher and having no weight loss at a temperature of 150 ° C. or lower in thermogravimetric analysis. 1 to 2.5% by weight is heated to a temperature of 150 to 180 ° C. to melt the thermoplastic resin, kneaded with the pigment and the fluorescent whitening agent, and then cooled and pulverized to obtain an average particle size of 5%.
The powder coating composition thus obtained is dry-coated on a substrate, guided to a heating roll having a temperature in the range of 150 to 200 ° C., heated and melted, and fixed. A method for producing a powder coating sheet. 5. The fluorescent whitening agent according to claim 4, wherein the number of particles having a particle diameter of 5 μm or less is 50% or more, and the number of particles having a particle diameter of 10.6 μm or less is 90% or more. Production method of powder coating sheet. 6. The method according to claim 4, wherein the pigment is a white pigment. 7. A pigment, a thermoplastic resin having a softening point of 150 ° C. or less, and a fluorescent whitening agent having a melting point of 150 ° C. or more and having no weight loss at a temperature of 150 ° C. or less in thermogravimetric analysis. 1 to 2.5% by weight is heated to a temperature of 150 to 180 ° C. to melt the thermoplastic resin, kneaded with the pigment and the fluorescent whitening agent, and then cooled and pulverized to obtain an average particle size of 5%.
To 30 μm, and 0.5 to 12% by weight of inorganic fine particles having an average particle diameter of 1 to 1 μm in the powder coating composition thus obtained.
Into a powder mixture, dry-coating the powder mixture on a substrate, guiding the powder mixture to a heating roll having a temperature in the range of 150 to 200 ° C., heating and melting, and fixing. Manufacturing method of powder paint coated sheet. 8. The fluorescent whitening agent according to claim 7, wherein the number of particles having a particle diameter of 5 μm or less is 50% or more, and the number of particles having a particle diameter of 10.6 μm or less is 90% or more. Production method of powder coating sheet. 9. The method according to claim 7, wherein the inorganic fine particles are hydrophobic inorganic fine particles as an image receiving sheet for thermal transfer recording of a sublimable dye. 10. The method according to claim 7, wherein the inorganic fine particles are hydrophilic inorganic fine particles as an image receiving sheet for ink jet recording. 11. The method according to claim 7, wherein the pigment is a white pigment.