JP2000118128A - Manufacture of thermal transfer image receiving sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture efficiently a thermal transfer image receiving sheet of given quality free from the defective coating of a powdery coating material composition in a method of forming a dye image receiving layer by using the powdery coating material composition and manufacturing the thermal transfer image receiving sheet. SOLUTION: In a thermal transfer image receiving sheet manufacturing method, a powder layer is formed by making a powdery composition containing a dye uptake resin adhere on a base by the static powder coating process, and the powder layer is heat melted and fixed to form an image receiving layer. In that case, when the powder composition 18 is made to adhere on the base 2 uniformly, a conductive material belt 15 is made to adhere on the opposite face of an acceptive layer forming face, and the conductive material is ground and earthed to increase the adhesion amount of the charged powdery composition 15 on the base 2 and manufacture a thermal transfer image receiving sheet.

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 used in combination with a sublimation type thermal transfer sheet.
The present invention relates to a method for producing a thermal transfer image-receiving sheet having a dye receiving layer formed on plain paper using a powder composition.

[0002]

2. Description of the Related Art Conventionally, as an image receiving sheet of a thermal transfer recording system using a sublimable dye, a composition containing a resin having a dye-dyeing property is coated on the surface of a base sheet such as synthetic paper, and dried to form a dye. Those formed with a receiving layer are known.

[0003] In the conventional thermal transfer image-receiving sheet, the dye-receiving layer has been manufactured using a solvent-type coating composition.
In recent years, a method for producing a thermal transfer image-receiving sheet using a powder coating composition as a composition of a dye receiving layer has been proposed (for example, JP-A-8-112974, JP-A-8-2).
No. 24970). A powder coating composition (a so-called toner) is prepared by melt-kneading a powder coating composition containing a resin component, a white colorant, a charge controlling agent, an anti-offset agent, etc., cooling, and then pulverizing to obtain an appropriate average particle size. What classifies so that it may have is used.

[0004] In the above-mentioned publication, there is a description of an electrophotographic production method as a method for forming a dye receiving layer. In this method, toner is charged on the surface of a sheet serving as a base material such as plain paper by frictional charging or the like, and the toner is attached to the drum surface charged to the opposite polarity by electrostatic attraction. It is transferred to the base material, heated and fixed.

In an electrophotographic copying machine or a laser printer, the drum surface is formed of a photoconductor. As one example of this method, after charging the entire drum surface by corona charging or the like, a desired image portion is neutralized by light irradiation to form a so-called electrostatic latent image, and a powder coating composition is formed on the latent image. There is a means for adhering an object, passing through the above-described transfer and fixing steps, and finally forming a desired image on the substrate to be transferred.

[0006]

However, in order to industrially produce a thermal transfer image-receiving sheet of a constant quality, it is difficult to eliminate unevenness in coating amount, coating defects, and the like in the electrophotographic system. To solve these problems, smoothness of the drum surface and uniform charging of the drum surface are absolutely essential, but it is extremely difficult to completely and uniformly charge a certain area or more. Also, the toner coating
The upper limit of the fixing speed is the speed of a copying machine, and the manufacturing speed is limited. Therefore, it is practically impossible to industrially mass-produce a thermal transfer image-receiving sheet of a constant quality by a conventional production method using an electrophotographic method.

An object of the present invention is to provide a method for producing a thermal transfer image-receiving sheet by providing a dye image-receiving layer using a powder coating composition. It is an object of the present invention to provide a method for manufacturing a thermal transfer image receiving sheet that can efficiently manufacture a thermal transfer image receiving sheet of a constant quality without any processing defects.

[0008]

According to the present invention, there is provided (1) a powder layer containing a dye-dyeable resin adhered to a substrate by an electrostatic powder coating method to form a powder layer; A method for producing a thermal transfer image-receiving sheet for forming an image-receiving layer by heating and fusing and fixing a body layer, when the powder composition is uniformly adhered on a substrate,
A conductive material is brought into close contact with the surface opposite to the receiving layer forming surface, and the conductive material is grounded and grounded to increase the amount of the charged powder composition attached to the substrate. Method for manufacturing thermal transfer image-receiving sheet, (2) After applying the powder composition uniformly on the substrate, static electricity is removed before the substrate is peeled off from the conductive material, and the coating surface is disturbed by peeling discharge (3) The method for producing a thermal transfer image-receiving sheet according to the above (1), wherein the powder composition is uniformly applied on a substrate and then sandwiched between two heat rolls to obtain a powder. (4) The method for producing a thermal transfer image-receiving sheet as described in (1) or (2) above, wherein the body composition is heated and fixed to form a receptor layer. When powder coating is performed and the base material peels from the conductive material belt after electrostatic powder coating (1) The method for producing a thermal transfer image-receiving sheet as described in any one of (1) to (3) above, wherein the powder layer is prevented from being disturbed by peeling discharge, and (5) after applying an antistatic agent to the substrate. Perform electrostatic powder coating, when the substrate is peeled from the conductive material belt after the electrostatic powder coating,
The method for producing a thermal transfer image-receiving sheet according to any one of the above (1) to (3), wherein disturbance of the powder layer due to peeling discharge is prevented, and (6) electrostatic powder coating on a substrate. (1) to (5), wherein after the powder layer is provided, preheating is performed by an indirect heating method, and then fixing is performed.
The method for producing a thermal transfer image-receiving sheet according to any one of the above,
(7) After providing a powder layer on a substrate by electrostatic powder coating,
The method for producing a thermal transfer image-receiving sheet according to any one of the above (1) to (6), wherein the fixing angle by the hot roll is 120 ° or less. It is the gist.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. The production method of the present invention is, as shown in FIG. 1, a base material 2 made of plain paper or the like, and a powder layer 3 made of a powder composition containing a dye-dyeable resin formed on a base material 2 by electrostatic powder coating. After the powder layer 3 is provided, the powder layer 3 is heated and melted, and is pressed and fixed as necessary to form a receiving layer 4. As shown in FIG. 2, the receiving layer 4 is provided on the base material 2. This is a method for producing the thermal transfer image-receiving sheet 1.

As the base material 2, plain paper, synthetic paper, plastic film and the like are used, and plain paper is preferred. As the plain paper used for the base material 2, a paper mainly composed of pulp that is usually used is used. For example, as plain paper,
Examples include high quality paper, art paper, lightweight coated paper, lightly coated paper, coated paper, cast coated paper, synthetic resin or emulsion impregnated paper. The thickness of plain paper is 40-300μ
m, preferably about 60 to 200 μm. In order to give the resulting thermal transfer image-receiving sheet a high texture of plain paper, the total thickness of the thermal transfer image-receiving sheet is desirably about 80 to 200 μm.

The receiving layer 4 is formed from a powder composition mainly composed of a dye-dyeable resin. The powder composition, in addition to the dye-dyeable resin, a release agent for preventing the receiving layer from fusing with the thermal transfer sheet when used after being used as a thermal transfer image-receiving sheet, when producing a thermal transfer image-receiving sheet A charge control agent for adjusting the chargeability as a powder coating, a white colorant for imparting concealment, an anti-offset agent, a fluidity improver, and the like can be added thereto.

The dye-dyeable resin is, for example, a saturated polyester resin, polyamide resin, polyacrylate resin, polycarbonate resin, polyurethane resin, polyvinyl acetal resin, polyvinyl chloride resin, polyvinyl acetate resin, polystyrene resin, styrene-acrylic resin. Resin, styrene-butadiene copolymer resin, vinyl chloride-vinyl acetate copolymer resin, vinyl toluene-acryl resin, cellulose resin and the like. These resins are
They can be used alone or in combination of two or more.
The amount of the dye-dyeable resin is 70% by weight in the powder composition.
If it is less than 70%, the dye-dyeing property is not sufficiently exhibited, and the printing sensitivity may be lowered. Therefore, it is preferable to use 70% by weight or more of the powder composition.

As a releasing agent to be added to the powder composition, silicone oil, phosphate ester plasticizer, fluorine compound, various waxes and the like can be used, but silicone oil is preferable. As silicone oil,
Epoxy modification, alkyl modification, amino modification, carboxyl modification, alcohol modification, fluorine modification, alkyl aralkyl polyether modification, epoxy polyether modification,
A modified silicone oil such as a polyether-modified silicone oil is preferably used. Among them, a reaction product of a vinyl-modified silicone oil and a hydrogen-modified silicone oil, and an amino-modified silicone and an epoxy-modified silicone, or a modified silicone having active hydrogen and active hydrogen A cured product of a curing agent that reacts with the above is preferred. The curing agent having active hydrogen is a non-yellowing type isocyanate compound, specifically, XDI, hydrogenated XDI, TMXDI, HDI, IDI
PDI and the respective adducts / burettes, oligomers and prepolymers are preferred. As the wax, those having a melting point in the range of 50 to 150 ° C. are preferable. For example, fluid or solid paraffin, polyolefin wax such as polyethylene and polypropylene, aliphatic metal salt, fatty acid ester, partially saponified fatty acid ester, higher fatty acid, higher fatty acid Examples include alcohols, silicone varnishes, amide waxes, aliphatic fluorocarbons and modified products thereof. The addition amount of the release agent is preferably 0.2 to 30 parts by weight based on 100 parts by weight of the resin forming the dye receiving layer.

The charge control agent added to the powder composition is for controlling the charging polarity and the charge amount of the powder composition when performing the electrostatic powder coating, and is a known electrostatic latent agent. What is used for the toner for image development can be used. Examples of negatively chargeable charge control agents include 2: 1 metal-containing azo dyes,
Examples thereof include metal complexes of aromatic oxycarboxylic acids and aromatic dicarboxylic acids, sulfonylamine derivatives of copper phthalocyanine dyes, and sulfonamide derivative dyes of copper phthalocyanine. Examples of the positive charge control agent include various nigrosine dyes in addition to quaternary ammonium compounds, alkylpyridinium compounds and alkylpicolinium compounds. The addition amount of the charge control agent is preferably 0.1 to 10 parts by weight, particularly preferably 0.3 to 5 parts by weight, based on 100 parts by weight of the resin of the receiving layer.

The white colorant added to the powder composition is for imparting hiding power and whiteness to the dye-receiving layer.
Examples include calcium carbonate, talc, kaolin, titanium oxide, zinc oxide and the like. The amount of white colorant added is
The amount is preferably 10 to 200 parts by weight based on 100 parts by weight of the resin of the dye receiving layer. If the amount of the white colorant is less than 10 parts by weight, the effect of adjusting the color tone is poor, and if it exceeds 200 parts by weight, the dispersion stability in the dye receiving layer is reduced, and the performance of the resin in the dye receiving layer is sufficiently obtained. It may not be possible.

The flow modifier added to the powder composition includes:
This is for improving the fluidity of the powder composition, and examples thereof include hydrophobic silica.

The powder composition may contain coloring materials such as various pigments, dyes and fluorescent brighteners as components other than the above components. When a thermal transfer image receiving sheet is used as a proofreading output material for printing proofreading, and when the color tone is matched with the corresponding printing paper, a desired color tone can be obtained by appropriately blending these colorants in the powder composition.

The above-mentioned powder composition is appropriately mixed, then melted, kneaded, uniformly dispersed, and then cooled.
After pulverization, if necessary, it is obtained by classifying to a desired average particle size. The average particle size of the powder composition is 1 to
It is preferably 30 μm, more preferably 5 to 15 μm.

When paper is used as the base material, the receiving layer 4 formed from the powder composition preferably has a substantial thickness of 7 μm or more. If the thickness of the receiving layer is less than 7 μm, there is a possibility that sufficient image quality and printing sensitivity may not be achieved due to the influence of surface irregularities derived from the pulp shape of the plain paper as the base material. Further, if the substantial thickness of the receiving layer 4 is 7 μm or more, the image quality and the printing sensitivity are satisfied.
The upper limit is not particularly limited, but if the thickness of the receiving layer is unnecessarily thick, the cost increases. Therefore, the upper limit of the substantial thickness is preferably 30 μm.

The actual thickness of the receiving layer 4 is determined by the thickness of the plain paper as the base material before coating and the thickness of the thermal transfer image-receiving sheet after the powder composition is coated and fixed to form the receiving layer 4. It can be determined by measuring. The inside of the dye receiving layer may be a discontinuous coating layer in which voids, cracks, and the like are formed, as long as the measured thickness is 7 μm or more. In order to make the thickness 7 μm or more, 1) the coating amount of the powder composition is set to a certain value or more. 2) The heating temperature and the pressing pressure are adjusted to melt the powder composition and permeate the plain paper. And the like.

FIG. 3 shows an apparatus for producing a thermal transfer image-receiving sheet by electrostatic powder coating, which is suitably used in the production method of the present invention.
It is explanatory drawing which shows an example. The production apparatus shown in FIG. 3 includes a payout roll 5 for feeding out a roll around which a long base material 2 is wound, and a powder coating for applying powder to the base material 2 to form a powder layer 3. From an electrostatic coating booth 6, a fixing device 7 for melting the powder layer 3 into the receiving layer 4, guide rolls 8, 9 and a winding device 10 for winding the formed thermal transfer image receiving sheet. It is configured. Further, in the apparatus shown in FIG. 3, a spraying device 11 for spraying an antistatic agent onto the base material 2 is installed in front of the electrostatic painting booth 6, and a spraying device 11 is provided between the electrostatic painting booth 6 and the fixing device 7. Is provided with a preheating device 12.

Inside the electrostatic coating booth 6, above the substrate 2, an electrostatic coating gun 1 for supplying a powder composition.
3, and a static eliminator 14 are provided. On the other hand, a conductive material belt 15 is provided below the substrate 2 so as to move in the booth while being in contact with the substrate 2. The inside of the electrostatic coating booth 6 is sealed so that the powder composition does not scatter outside, and a nozzle 17 connected to a dust collector 16 is mounted inside.

The electrostatic coating gun 13 is connected to a storage tank 19 for the powder composition 18 and is configured to transport the powder composition 18 by a driving force such as air. A needle-shaped or ring-shaped corona electrode (not shown) is provided near the outlet at the tip of the electrostatic coating gun 13.
The powder composition is formed so as to be chargeable. This charging voltage is usually formed so that about -20 to -80 kv can be applied.

The belt 15 made of a chargeable material is formed endlessly by conductive rubber, steel, or the like, and is formed to be supported by two rolls and rotated by a driving device.

The fixing device 7 includes two heat rolls 20 and 21 so as to sandwich the substrate 2 from above and below, and is formed so that the substrate 2 can be pressed. Further, a guide roll 8 provided after the heat rolls 20 and 21 of the fixing device.
Is formed so that the position thereof can be arbitrarily changed, and is configured so that the angle of the substrate exiting from the hot rolls 20, 21 can be changed.

Hereinafter, the method for producing the thermal transfer image-receiving sheet of the present invention will be described with reference to FIG. First, the base material 2 is sent out from the feeding roll 5 and sent to the electrostatic painting booth 6. Inside the electrostatic coating booth 6, the base material 2 moves while the lower side is grounded and is in contact with the grounded conductive material belt 15. From above the base material 2, the powder composition 18 inside the storage tank 19 is moved by the air flow or the like to the electrostatic coating gun 13.
From the front end to the vicinity of the surface of the substrate 2. At this time, the powder composition 18 is negatively charged by the discharge of the corona electrode at the tip of the electrostatic spray gun 13, and the powder composition carried to the vicinity of the surface of the substrate 2 is charged by electrostatic attraction to the surface of the substrate 2. To form a powder layer 3. In order to charge the powder composition, a means for stirring the powder composition in a container and frictionally charging the powder composition with the inner wall surface of the container may be used.

In the electrostatic powder coating, the negatively charged powder composition accumulates on the base material having low conductivity such as paper and the powder composition hardly adheres. Therefore, as described above, a belt made of a conductive material is brought into close contact with the surface opposite to the surface on which the powder on the lower surface of the base material is coated, and the belt is grounded to make it easier for the electric charge to escape, so that the powder composition is reduced. The amount of the object 18 adhered to the substrate 2 can be increased.

When a plastic film is used in place of paper as a base material, an ordinary film has almost no conductivity, and a belt made of a conductive material is adhered to the surface opposite to the surface on which the powder composition is applied. Even if the ground is taken, the powder composition is very difficult to adhere. Thus, in the case of such a base material, an antistatic agent is uniformly applied on the base material 2 in advance by using a spraying device 11 or the like provided in front of the electrostatic coating booth 6, and By providing an antistatic layer on the surface of No. 2, it is easy for the electric charge to escape from the conductive material belt, and even if the powder composition is a substrate having almost no conductivity such as a plastic film, The body composition can be satisfactorily adhered.

In addition to spraying the antistatic agent on the substrate 2, the gravure printing method, screen printing method, printing such as reverse roll coating using a gravure plate, or a coating means may be used. Can be applied. Examples of the antistatic agent include fatty acid esters, sulfates, phosphates, amides, quaternary ammonium salts, betaines, amino acids, acrylic resins, and ethylene oxide adducts. The above antistatic agent can be dispersed and mixed in a solvent, a diluent, or the like to form an antistatic liquid by spraying, printing, or coating to form an antistatic layer. When the base material 2 is paper, the effect of preventing the powder layer from being disturbed by the peeling discharge can be obtained by simply using water to make the paper contain water. It is preferable to use it because a better effect can be obtained.

Although the powder composition adheres to the surface of the substrate by the above-mentioned electrostatic powder coating, the powder that does not adhere to the substrate floats in the booth because it is very small. The suspended powder composition is supplied from the nozzle 17 in the electrostatic painting booth to the dust collector 1.
Suctioned by 6 and collected.

After the powder layer 3 is formed by the electrostatic coating gun, the base material 2 is separated from the conductive material belt 15 which is in close contact, and is sent to the fixing device 7. When the substrate 2 is peeled off from the conductive material belt 15, a peeling discharge is generated, and the powder layer 3 attached to the substrate 2 may be disturbed and uneven due to the influence of the peeling discharge. In order to prevent this, it is preferable to perform corona discharge by the charge remover 14 immediately before the base material is separated from the belt 15 to remove the charge from the charged powder layer 3 and the base material 2. Due to the charge removal by the charge remover 14, peeling discharge is prevented, and the powder layer 3 can maintain a uniform powder layer 3 without generating a peeling discharge pattern. In addition, by spraying, printing, or applying the above-mentioned water or an antistatic agent to increase the conductivity of the base material itself, the charge can be easily released, and the same effect as above can be obtained.

The substrate 2 provided with the powder layer 3 exits from the electrostatic coating booth, and is subjected to preliminary heating by indirect heating by a preliminary heating device 12 made of a heating wire of nichrome or the like. The sheet is fed and heated and pressed between the heat rolls 20 and 21 to be fixed. Since the powder layer 3 is melted by the heat of the rolls and the pressure between the rolls is pressurized, the melted material has a smooth surface and is cooled and solidified after passing through the rolls.
Is provided with a receiving layer 4 formed as a continuous resin layer on the surface of the sheet, and the thermal transfer image-receiving sheet 1 is obtained.

The powder layer 3 provided on the substrate 2 by the electrostatic powder coating method can be fixed by heating or / and pressing to form the receiving layer 4. As the heating means at the time of this fixing, any of indirect heating using hot air, infrared rays, microwaves, or the like, or direct heating sandwiched between two heat rolls or two heat plates can be used. Direct heating with a hot roll is particularly preferred.

In the above-mentioned direct heating, it is preferable that the roll or the plate has been subjected to a fluorine treatment, preferably a PFA treatment, since the releasability from the powder composition becomes good. In the thermal transfer image-receiving sheet, since the uniformity of the surface of the image-receiving layer greatly affects the image quality and the like, it is extremely important to form the surface smoothly, so a direct heating means sandwiched between two rolls is effective. .

As shown in FIG. 3, two heat rolls 20, 2
In the case of fixing by the method 1, if the amount of heat is insufficient, the powder composition on the base material does not melt sufficiently and the heat roll 20 on the powder layer 3 side
Cold offset occurs where powder adheres to the surface. Also,
If the amount of heat at the time of fixing is excessive, the entire powder layer 3 is excessively melted, and cohesive failure of the powder layer 3 is likely to occur,
Hot offset occurs in which powder adheres to the roll 20 on the powder layer 3 side. The above-described cold offset and hot offset can be prevented by controlling the heating conditions so that the amount of heat applied to the powder layer 3 falls within an appropriate range.
The adjustment of the amount of heat depends on the temperature of the heat rolls 20 and 21 and the base material 2
, The degree of preheating described later, the hugging angle of the substrate coming out of the hot roll, and the like can be adjusted.

For example, using a plain paper as a base material, a powder composition is applied on the base material to form a powder layer, which is sandwiched between two heat rolls 20 and 21 for a sufficient time. When heated over time, no offset occurs. However, in order to improve the productivity, when the rotation speed of the hot roll is increased, the heating time is shortened, and the amount of heat is insufficient, so that the powder composition does not sufficiently melt, and the powder adheres to the roll side. Cold offset occurs. In order to prevent this cold offset, before performing heat fixing with two rolls,
It is preferable to perform preheating by a preheating device using an indirect heating means as shown in FIG.

By performing preheating, heat can be applied to the base material and the powder composition to raise the temperature immediately before fixing by the hot roll. At this time, a part of the powder layer 3 is melted, and the melted powder is fused to the unmelted powder and the substrate. Furthermore, since the temperature of the powder layer 3 and the base material 2 is already high when passing between the fixing heat rolls 20 and 21, sufficient fixing can be performed even if the heating time is short. Therefore, it greatly contributes to the improvement of productivity.

When fixing is performed by using two heat rolls 20 and 21, as shown in FIG.
Is passed straight through so as to be orthogonal to the line connecting the central axes of the heat rolls 20 and 21, and is similarly output perpendicularly to the line connecting the central axes of the heat rolls 20 and 21, whereby the base material 2 is heated. The distance L1 in contact with the heat roll becomes the shortest time. On the other hand, as shown in FIG. 5, when the substrate 2 is made to have an angle α when exiting from the hot roll, the distance L2 between the hot roll 20 and the substrate 2 is increased, and the heating time can be increased. . The above angle α is referred to as a holding angle.
The same effect can be obtained even if such a holding angle is provided on the side where the substrate 2 enters the heat roll.

When the production speed is increased by increasing the rotation speed of the heat rolls 20 and 21, the heating time applied to the base material is shortened. The amount of heat to be added to the air can be increased to prevent the occurrence of cold offset. This holding angle α is 180
°, but when fixing is carried out with the holding angle α too large, roughness of the surface of the receiving layer of the image receiving sheet is observed, and the offset at which a part of the resin of the receiving layer adheres to the heat roll 20 is reduced. Was seen. Therefore, the above-described holding angle is preferably set to 120 ° or less. The reason is as follows.

When the heating and fixing are performed with the holding angle α increased, as shown in FIG. 6, almost one of the heating rolls 21 on the side of the substrate 2 is heated. For this reason, the temperature difference between the surface side and the substrate side inside the powder layer becomes large. As a result, as shown in FIG.
In this case, the molten state of the heat roll 21 on the side of the base material 2 and the molten state of the heat roll 20 side are different from each other. Stickiness occurs. When the heat roll 20 is peeled off from the powder layer 3, a part of the powder layer 3 is pulled by the heat roll 20, so that the surface of the receiving layer is formed with irregularities and becomes rough. It is considered that the disturbance of the image occurs. Further, a portion near the surface of the powder layer 3 is completely melted, and cohesive failure occurs in the powder layer as shown in FIG.
A hot offset phenomenon occurs in which a part of the powder layer is separated and adheres to the surface of the heat roll 20.

When fixing was performed with the holding angle α exceeding 120 °, wrinkling was observed due to the long heating time. This is presumed to be due to expansion and contraction of paper fibers. Normally, when heated without being sandwiched between heat rolls, even if the fiber of the paper expands and contracts due to heating and causes wrinkles such as slack or tension, it slightly slides on the guide roll. By doing so, slack, tension and the like disappear momentarily, and no wrinkles occur. However, when the paper is sandwiched between the heat rolls, even if the paper fibers shrink due to heating, the paper is sandwiched between the two heat rolls and is in a pressurized state, so that the paper cannot slide and wrinkles occur. It is presumed to be done.

In the production method of the present invention, another layer can be formed on the thermal transfer image-receiving sheet having the above-mentioned receiving layer formed thereon in the same manner as described above.

When a thermal transfer image receiving sheet is used, a sublimation type thermal transfer sheet used in a sublimation transfer recording system is used as the thermal transfer sheet. Application of thermal energy at the time of thermal transfer can use a known means, for example,
An image can be formed by applying a thermal energy of about 5 to 100 mj / mm ² by controlling a recording time by a recording device such as a thermal printer (for example, a printer Rainbow M2720 manufactured by 3M).

[0044]

[Powder coating material composition (all units are parts by weight)]

 -80 parts of polyester resin (Mitsubishi Rayon Co., Ltd .: Diacron FC-611)-20 parts of styrene-acrylic resin (Mitsubishi Rayon Co., Ltd .: FB-206) 20 parts-Charge control agent (Orient Chemical Co., Ltd .: Bontron P-51) 4 Part ・ Titanium oxide (Tochem Products: TCA888) 2 parts ・ Amino-modified silicone (Shin-Etsu Chemical: X22-349) 1 part ・ Epoxy-modified silicone (Shin-Etsu Chemical: KF-393) 1 part

After the raw materials having the above composition were mixed by a mixer, they were heated and melted and kneaded by a melt kneader. The mixture was cooled and solidified, then pulverized and classified to obtain a powder composition having an average particle size of 8 μm. 2 parts by weight of a hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd .: RA-
200H) to obtain a powder coating.

The apparatus shown in FIG. 1 was used.
Using 44.7 g of high quality paper, delivery speed 10 m from the roll
/ Min and sent to the electrostatic painting booth. The electrostatic coating gun applied a high voltage of -80 kv from a high voltage generator to negatively charge the powder. In the electrostatic coating booth, the substrate was brought into close contact with a conductive rubber belt, and the rubber belt was grounded, and the powder could be uniformly distributed on the surface of the substrate by air pressure and electrostatic force. The amount of the powder composition applied was 10 g / m ² . Further, the powder that had not adhered to the base material and floated in the booth was minute, but was collected by suction using a dust collector. The powder adhering to the base material surface is subjected to corona discharge by a static eliminator, and the charged powder and the base material are discharged and separated from the conductive rubber belt. After the powder layer and the base material are preheated and heated by a heating wire, the temperature of the roll surface becomes 150
Under a condition of ℃ and a nip pressure of about 4 kg / 40 cm, the mixture was passed while sandwiching between hot rolls to melt the powder layer and form a receptor layer on the surface of the substrate. The surface roughness (R
a) is 0.2 μm, and the specular gloss of the roll surface (Gs45)
°) was 8%. The holding angle of the heat roll is 6
0 °. After passing through the heat roll, it was guided by a guide roll and wound up by a take-up roll.

[Electrostatic powder coating method] ・ Electrostatic powder coating apparatus: GX5000S, manufactured by Nippon Parkerizing Co., Ltd. ・ Hand gun: GX106N, manufactured by Nippon Parkerizing Co., Ltd. [Fixing conditions] ・ Heat roll diameter: Both the receiving layer side and the back side Diameter 80mm ・ Heat roll material: Surface treatment of PFA on iron roll ・ Heating temperature: 150 ° C on the receiving layer side, 150 ° C on the back side ・ Roll speed: 10mm / min ・ Pressure pressure: 2kg per roll length 25cm ・ Roll surface roughness (Ra): Both rolls are 0.5 μm. Roll specular gloss (Gs 45 °): 8.0%

EXPERIMENTAL EXAMPLES 2-11 Various manufacturing conditions in Example 1 were changed, and the effects were examined as described below. Experimental Example 2 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1, except that the conductive rubber belt was an insulating rubber belt. Experimental Example 3 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1, except that the conductive rubber belt was a steel belt. Experimental Example 4 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the static eliminator by corona discharge was not used. Experimental Example 5 Water was sprayed on the base material by the sprayer 13 to cause water to be contained therein.
A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1, except that the static eliminator by corona discharge was not used. Experimental Example 6 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1, except that an antistatic layer was provided on a base material in advance and a static eliminator by corona discharge treatment was not used. Experimental Example 7 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the preheating was not performed using nichrome heating wire. Experimental Example 8 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the unwinding and winding speed was 5 m / min, and the preheating was not performed with the heating wire 8 of nichrome. Experimental Example 9 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the holding angle was set to 0 °. Experimental Example 10 The hugging angle was set to 0 °, and the paper was unwound and the winding speed was 3
A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1 except that the rate was m / min. Experimental Example 11 A thermal transfer image-receiving sheet was obtained in the same manner as in Example 1, except that the holding angle was 120 °.

The thermal transfer image-receiving sheets of the above Examples and Experimental Examples were evaluated for adhesion to a substrate during powder coating, disturbance due to peeling discharge, and offset when passing through a hot roll in the production stage. Further, the thermal transfer image receiving sheets of Examples and Experimental Examples were evaluated for uniformity of the coated surface, roughness, presence or absence of wrinkles, and defective fixing. Further, the thermal transfer image-receiving sheets of Examples and Experimental Examples were printed using a sublimation transfer printer Rainbow 2720 manufactured by 3M and a dye transfer film for the printer, and each evaluation of print image quality and print sensitivity was performed. Table 1 shows the results of these evaluations. Each evaluation method is as follows.

[0050]

[Table 1]

[Adhesion of Powder Composition to Substrate During Electrostatic Powder Coating] The degree of adhesion of the charged powder composition to the substrate during electrostatic powder coating was visually observed. ：: The charged powder composition adheres to the substrate. X: The charged powder composition hardly adheres to the substrate.

[Offset] When heat and pressure are fixed using a hot roll, the amount of heat is insufficient, or the amount of heat is excessive, so that the powder is not fixed only on the base material and is fixed to the hot roll. The observed phenomenon (offset) was observed. ：: Offset occurs. X: No offset occurs.

[Peeling Discharge Pattern] The receiving layer surface of each thermal transfer image-receiving sheet was visually observed, and a pattern caused by powder disturbance caused by peeling discharge was visually evaluated. ：: No disturbance of the powder composition due to peeling discharge. X: Disturbance of the powder composition due to peeling discharge.

[Roughness of Coated Surface of Powder Composition] Each thermal transfer image-receiving sheet was visually observed to evaluate whether the powder was uniformly applied. ：: No roughness occurs on the coated surface. ×: Roughness occurs on the coated surface.

[Wrinkles] After heating and fixing using a heat roll, the substrate was observed for occurrence of wrinkles. ：: No wrinkles occurred on the substrate. X: Wrinkles are generated on the substrate.

[Print quality] Bk single color density (25% / 10
0%) Bk single color (10%) of solid, 1 dot and 2 dot width
0% / 100%) Fine line, Bk single color (100% / 100%)
%) A character image was prepared and subjected to printing and image evaluation. The print image quality was visually evaluated by sensory evaluation according to the following evaluation criteria. ：: good without missing prints, fine lines, etc. X: Print missing, fine line fading is remarkable.

[Printing Sensitivity] Mg single-color solid image (70% /
100%) and subjected to printing and sensitivity evaluation. The printing sensitivity was measured by GRETAG SPM50 and evaluated according to the following evaluation criteria. ：: OD value 0.9 or more ×: OD value less than 0.8

[0058]

As explained above, the production method of the present invention
In a method for producing a thermal transfer image receiving sheet by providing a dye image receiving layer using a powder coating composition, there is no coating defect of the powder coating composition, and a thermal transfer image receiving sheet of constant quality can be efficiently produced. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a thermal transfer image receiving sheet showing a state in which a powder layer is provided on a substrate.

FIG. 2 is a cross-sectional view showing one example of a thermal transfer image receiving sheet obtained by the production method of the present invention.

FIG. 3 is a schematic view showing one example of a production apparatus suitably used in the production method of the present invention.

FIG. 4 is an explanatory diagram showing a case where the holding angle α is 0 °.

FIG. 5 is an explanatory diagram showing a case where the holding angle α is 60 °.

FIG. 6 is an explanatory diagram showing a case where the holding angle α is 120 °.

FIG. 7 is an enlarged view of a main part for describing a state where an offset has occurred when the holding angle α exceeds 120 °.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal transfer image-receiving sheet 2 Substrate 3 Powder layer 4 Reception layer 5 Feeding roll 6 Electrostatic coating booth 7 Fixing device 8, 9 Guide roll 10 Winding roll 11 Antistatic spraying device 12 Preheating device 13 Electrostatic coating gun 14 Static eliminator 15 Conductive material belt 18 Powder composition 20, 21 Hot roll

Claims (7)

[Claims] Claims: 1. A powder layer containing a dye-dyeable resin is attached to a substrate by an electrostatic powder coating method to form a powder layer.
A method for producing a thermal transfer image-receiving sheet wherein the powder layer is heated and melted and fixed to form an image-receiving layer, wherein when the powder composition is uniformly deposited on a substrate, a conductive layer is formed on the surface opposite to the receiving layer-forming surface. A method for producing a thermal transfer image-receiving sheet, comprising: bringing a conductive material into close contact, grounding the conductive material and grounding to increase the amount of the charged powder composition adhering to the substrate. 2. After the powder composition is uniformly applied on a substrate, static electricity is removed before the substrate is peeled off from the conductive material, thereby preventing disturbance of the coated surface due to peeling discharge. The method for producing a thermal transfer image-receiving sheet according to claim 1. 3. The method according to claim 1, wherein the powder composition is uniformly applied on a substrate, and then sandwiched between two heat rolls to heat and fix the powder composition to form a receptor layer. Claim 1 or 2
The method for producing the thermal transfer image-receiving sheet according to the above. 4. An electrostatic powder coating is performed after spraying an antistatic agent onto a base material, and when the base material is separated from the conductive material belt after the electrostatic powder coating, a powder layer is generated by peeling discharge. The method for producing a thermal transfer image-receiving sheet according to any one of claims 1 to 3, wherein the disturbance is prevented. 5. An electrostatic powder coating is performed after applying an antistatic agent to a base material, and when the base material is separated from the conductive material belt after the electrostatic powder coating, a powder layer is formed by peeling discharge. The method for producing a thermal transfer image-receiving sheet according to any one of claims 1 to 3, wherein the disturbance is prevented. 6. After providing a powder layer on a substrate by electrostatic powder coating, after performing preliminary heating by an indirect heating method,
6. The method according to claim 1, wherein fixing is performed.
3. The method for producing a thermal transfer image-receiving sheet according to item 1. 7. A fixing method using a hot roll after providing a powder layer on a base material by electrostatic powder coating, wherein the holding angle of the base material coming out of the hot roll is 120 ° or less. The method for producing a thermal transfer image receiving sheet according to any one of claims 1 to 6.