JP3293535B2 - Melt type thermal transfer recording paper - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording paper used in a printer of a fusion type thermal transfer system for performing multi-gradation image recording, and more particularly to a recording paper having good paper feedability and transportability in the printer. The present invention relates to a fusion type thermal transfer recording paper.

[0002]

2. Description of the Related Art Conventionally, a dither method using a plurality of pixels (matrix) or a special thermal head having a small heating resistor has been used to realize multi-tone printing with a heat-meltable ink. Heat concentration method is applied (for example, Photo Industry Publishing Co., Imaging Par
t1, see p103 to p108). In general, in the method using a plurality of pixels described above, there is a problem that the resolution is deteriorated and the image quality is remarkably reduced. In the method using a special thermal head, there is a problem that the cost is increased. In view of this, recently, as a method capable of obtaining a gradation for each pixel, a fusion type thermal transfer recording method using a recording paper having an ink receiving layer formed of a porous material on the surface has been proposed (television set). Conference technical report, IT
E Technical Report, Vol. 17,
No. 27 (May 1993). See pages 19-24). In this method, when the molten ink is transferred from the thermal transfer recording ink ribbon to the porous layer on the surface of the recording paper, the molten ink penetrates into the pores of the porous layer, and a very small amount is caused by the anchoring effect. It is also possible to transfer with ink. Thereby, the molten ink can be transferred from the ink ribbon to the recording paper in accordance with the heating amount in pixel units. Furthermore, not only the porous layer described above, but also
It has been confirmed that a similar effect can be obtained even with a multi-grooved layer, that is, an ink receiving layer having a large number of narrow grooves, as disclosed in Japanese Patent No. 246785.

[0003] Thermal transfer recording paper having an ink receiving layer formed of such a porous layer or a multi-groove layer on its surface can certainly record multi-gradation images. It is required to have excellent performance. Specifically, high recording density (good adhesion and fixability of the molten ink), high surface gloss, no or little curl before and after printing, etc. However, it is particularly important in practical use that the paper supply / discharge property of the printer device is good.

As a method of forming a porous layer or a multi-grooved layer, for example, there is a wet coagulation method generally used in a process of producing artificial leather. In this method, a substrate coated with a dimethylformamide (DMF) solution of a resin is treated in water to replace DMF with water, whereby the resin is coagulated and dried, and simultaneously becomes porous. As the resins, urethane resins are generally used because they have a unique texture, are easily processed by the wet solidification method, and have a high degree of freedom in designing as a polymer material. On the other hand, a back coat layer is provided on the other surface of the recording paper having such a porous layer on the surface in order to secure paper supply / discharge performance as the recording paper. The back coat layer facilitates the feeding of recording paper, prevents double feeding that occurs when two or more recording papers are stacked, and prevents paper jams in the transport path and paper discharge section of the printer. Therefore, a function to reduce the coefficient of friction is required.

[0005]

In a recording paper having a porous layer or a multi-groove layer, the porous layer or the multi-groove layer is provided with a cushioning property in order to soften the contact with the thermal head. . For this reason, the coefficient of friction tends to be large with respect to the space between recording sheets and the material of the conveyance path in the printer, and the smoothness tends to be insufficient. Therefore, as described above, the recording paper needs to be provided with a back coat layer to which a lubricant is added. The problem that arises at this time is that in order to obtain sufficient lubrication, the amount of the liquid or semi-solid lubricant must be large enough to cause adverse effects such as blocking. If the amount of these lubricants is increased or the coating of the lubricant itself is used as a back coat layer, the lubricant contains many low-molecular-weight organic compounds, and bleeds to the surface to form a porous layer or a multi-grooved layer. In some cases, the lubricant may be transferred or stickiness may occur to cause blocking between recording sheets. Further, the lubricant transferred to the porous layer or the multi-grooved layer as described above hinders the transfer of the molten ink, and causes a deterioration in image quality in high-quality recording. SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermal transfer recording method in which a lubricant is not transferred to an ink-receiving layer of a porous layer or a multi-grooved layer, and a back coat layer which realizes a sufficient paper supply / discharge performance for a printer. To provide paper.

[0006]

In order to solve the above-mentioned problems, the present invention has an ink receiving layer having a cushioning property comprising a porous layer or a multi-groove layer on one side, and has an ink receiving layer on the other side. In a fusion-type thermal transfer recording paper having a back coat layer, the back coat layer contains fine particles of tetrafluoroethylene resin, and the pore diameter R of the porous layer is 1 μm or more and 30 μm or more.
m or less, and the groove width L of the multi-grooved material layer is 1 μm or more and 30 μm or less.
Is lower, the 4 average particle diameter φ of tetrafluoroethylene resin particles, larger than the thickness T of the porous layer the pore size R or larger than the groove width L of the multi-grooved porous layer and the back coating layer in particular from the said back coat layer ink
Measurement according to JIS-K-7125 with the surface of the receiving layer
The coefficient of dynamic friction by the conventional method is 0.5 or less, and
Melt-type thermal transfer recording paper characterized in that the static friction coefficient according to a standard method is 1.5 or less .

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have developed a back coat which does not transfer a lubricant to an ink receiving layer of a porous layer or a multi-grooved layer, and realizes a sufficient paper supply / discharge performance for a printer. In order to develop the layer, intensive research was conducted on the lubricant used for the back coat layer. As a result, the average particle diameter φ
Is the pore diameter R of the porous layer or the groove width L of the multi-grooved layer.
By adding tetrafluoroethylene resin fine particles, which are larger and larger than the thickness T of the back coat layer, to the back coat layer as a lubricant, it has been found that a melt-type thermal transfer recording paper solving the problem can be obtained. Since the tetrafluoroethylene resin fine particles are a solid lubricant, there is no transfer to the ink receiving layer irrespective of the added amount. First, a thermal transfer recording system for applying the fusion type thermal transfer recording paper of the present invention will be described with reference to the drawings. As shown in FIG. 1, between the thermal head 3 and the platen roller 4,
The melt-type thermal transfer recording paper 2 and the ink ribbon 1 are superimposed and conveyed, the thermal head 3 is pressed against the platen roller 4, and a heating resistor (not shown) of the thermal head 3 is heated to 1 to a porous layer 2a formed on a recording paper 2
To obtain a recorded image.

In general, the heating resistor of the thermal head 3 is generally formed in a rectangular shape. The temperature distribution of the heating resistor is provided with a temperature gradient that is highest at the center and becomes lower toward the periphery, and a portion of the ink ribbon 1 at a temperature higher than the melting temperature of the ink is melted. By utilizing this temperature gradient, the melting area of the ink can be controlled. When the temperature of the ink ribbon 1 is equal to or higher than the melting point, the higher the temperature, the lower the viscosity of the ink is. Since the viscosity becomes high, the amount of ink penetrating into the recording paper 2 having the porous layer or the multi-grooved layer on the surface of the recording paper base is correspondingly large in the central portion and smaller in the peripheral portion. Therefore, if the current flowing through the heating resistor is changed in accordance with the gradation of the image to be recorded, the amount and area of ink penetration are simultaneously controlled, so that multi-gradation recording is possible.

Next, the structure of the recording paper of the present invention will be described. FIG. 2A shows that a porous layer 2 is formed on one side of a substrate 2.
a, the recording paper 2 on which the back coat layer 2c is formed on the other surface side. FIG. 2B shows a recording paper 2 'in which a multi-grooved layer 2a' is formed on one side of a base 2b and a back coat layer 2c is formed on the other side. Examples of the recording paper substrate 2b include transparent or opaque plastic films such as a polyethylene terephthalate film, a polyimide film, a polyethylene naphthalate film, a polypropylene film, a polyamide film, and an aramid film; uncoated paper such as high-quality paper and PPC paper; Fillers and additives are added to papers such as paper and coated papers such as coated papers, synthetic resin, mixed, melt-kneaded and extruded from die slits to form a film. For example, synthetic papers such as Oji Yuka Synthetic Paper Co., Ltd., trade name YUPO) and synthetic papers such as synthetic paper by a surface coating method in which a white pigment coating layer is provided on the surface of a plastic film, and further, these sheet-like substrates are laminated. Base materials and the like can be given. Among them, for example, synthetic paper (for example, manufactured by Oji Yuka Synthetic Paper Co., Ltd., trade name: YUPO) by the internal paper forming method has water resistance, solvent resistance, heat resistance, surface smoothness, whiteness, strength and the like. It is excellent in that it is preferable as a recording paper substrate. The thickness of the recording paper substrate 2b is preferably about 25 to 500 μm, more preferably about 50 to 500 μm, from the viewpoints of mechanical strength, appropriate rigidity as recording paper, ease of handling, and price. ３００300 μm.

Next, as a method for forming the porous layer 2a formed on the surface of the recording paper substrate, a general method for forming a porous layer can be used. Specifically, for example, a DMF (dimethylformamide) solution of resins is applied on the base 2b and treated in water to obtain a DMF.
Wet coagulation method, which replaces water with water, coagulates and dries the resin, and at the same time makes the resin porous, adds a foaming agent and a foam stabilizer to the aqueous resin solution and stirs to mechanically generate foam, "Mechanical stirring foaming method" to form a porous layer by forming a foam solution, "Pigment addition method" to form a porous layer using porous pigments (inorganic and organic fine particles, etc.).
For certain polymers, add a good solvent and a poor solvent or a non-solvent with a higher boiling point to make a polymer solution,
This is coated and dried, first evaporating a good solvent having a low boiling point, leaving a poor solvent or a non-solvent in the coating film, and gelling a polymer having low solubility in these solvents,
Subsequently, the "solvent solubility method" in which the poor or non-solvent having a high boiling point is evaporated and the volatilized traces become porous, an organic and inorganic compound foaming agent that generates a gas such as nitrogen gas when heated "Blowing agent method", using an inorganic powder such as salt and an organic powder such as starch in a resin coating film, dissolving and removing these powders by washing with water after forming the coating film. And the like.

The structure of the porous layer 2a is desirably a communication hole, and preferably has an escape path for air inside when the molten ink permeates. The depth of the pores of the porous layer depends on the thickness of the ink layer. For example, in the case of transferring using an ink ribbon having a 2 μm-thick four-color ink layer of yellow, magenta, cyan, and black, at least, 8 μm is required. The pore diameter R of the porous layer depends on the type of the coloring material, but is about 1 to 30 μm, and more preferably 1 to 1 μm.
It is preferably about 0 μm. In the case of pores larger than this range, the adhesiveness of the transferred ink tends to decrease, and the ink may return to the ink ribbon side without being transferred. Further, when the pores are smaller than the above range, it may be difficult for the ink to penetrate. The thickness of the porous layer 2a is desirably determined in consideration of the number of colors and thickness of the ink layer, the porosity of the porous layer, the strength as a coating film at the time of transfer, and the like. ~ 50
The range is about μm.

For forming the multi-grooved layer 2a ', a known fine processing technique can be used. For example, a plate-shaped or roll-shaped master having narrow grooves is produced by a known method, and this is superimposed on a recording paper substrate coated with a polymer layer for forming a multi-grooved layer, and heat and pressure are applied. By doing so, it is possible to copy and form the narrow grooves of the original plate on the polymer layer and to manufacture a recording paper with a multi-grooved layer. The production of the master includes, for example, a laser processing method, a chemical etching method using photolithography, a dry etching method, and the like.
The many narrow grooves are formed substantially in parallel or orthogonally, and the groove width is preferably about 1 to 30 μm. If the groove width is 1 μm or less, the ink may not easily penetrate. If the groove width is 30 μm or more, the ink may not easily penetrate by capillary action.

Next, the fine particles of ethylene tetrafluoride resin to be contained in the back coat layer, which is a main part of the present invention, will be described. As a result of various studies of solid lubricants, the tetrafluoroethylene resin fine particles were most effective in reducing the coefficient of friction with respect to the porous layer or the multi-groove layer and the coefficient of friction with respect to the material of the conveyance path in the printer. Things. In order to hold the tetrafluoroethylene resin fine particles in the back coat layer, a binder resin is required. As these binder resins, known thermoplastic resins, thermosetting resins, radiation-curable resins, and the like can be used. These are adhesion to recording paper substrate, dispersibility of amorphous organic resin fine particles,
The selection is made in consideration of economical efficiency, safety, the possibility of preparing a coating material suitable for the coating method, compatibility with other additives, and the like. Specifically, for example, polyester resin, polyurethane resin, epoxy resin, acrylic resin,
Ethylene-based resin such as ethylene-vinyl acetate copolymer, vinyl chloride-based resin such as vinyl chloride-vinyl acetate copolymer,
Emulsion types such as vinyl acetate resins, cellulose resins, polyamide resins, polyolefin resins, styrene resins, petroleum resins, etc., water-soluble types, and solvent-type types can be used.

Fine particles of ethylene tetrafluoride resin are added to these resins as the main components. At this time, the size of the tetrafluoroethylene resin fine particles is such that, when they come into contact with those surfaces of the recording paper having the porous layer or the multi-grooved layer, the pores of the porous layer or the grooves of the multi-grooved layer are formed. It must be large enough to fit. If the particles have a particle diameter smaller than the pore diameter or the groove width, the particles are anchored, and no lubricity can be obtained. Therefore, it is necessary that the average particle diameter φ of the tetrafluoroethylene resin fine particles contained in the back coat layer is larger than the pore diameter R of the porous layer or the groove width L of the multi-grooved layer. Furthermore, the tetrafluoroethylene resin fine particles contained in the back coat layer cannot function as a solid lubricant unless they protrude onto the binder resin layer in the back coat layer. Therefore, the average particle diameter φ of the tetrafluoroethylene resin fine particles must be larger than the backcoat layer thickness T. The back coat layer may further contain an antistatic agent for preventing electrostatic damage, a liquid lubricant for assisting the lubrication of the solid lubricant, a colorant, a pigment, and the like. The coefficient of dynamic friction between the back coat layer containing the fine particles of the tetrafluoroethylene resin and the surface of the ink receiving layer having the porous layer or the multi-grooved layer is JIS-K-71.
It is preferable that the coefficient of static friction be 0.5 or less in the measurement method based on No. 25 and 1.5 or less in the same method. Above the above values, the slippage between the recording sheets may be insufficient, and in this case, multi-feeding in which two sheets are fed in a stacked state is likely to occur. If the coefficient of dynamic friction is 0.5 or less and the coefficient of static friction is 1.5 or less, more excellent and excellent lubricity can be obtained.

Examples 1 and 2 and Comparative Examples 1 to 5 shown below
Hereinafter, the present invention will be specifically described. Using the various resin fine particles shown in Table 1, the following back coat layer compositions for Examples 1 and 2 and Comparative Examples 1 to 5 were respectively prepared. A solution composed of this composition was mixed with synthetic paper (Oji Yuka Synthetic Paper Co., Ltd., F
(PG-150, thickness 150 μm) using a doctor blade and dried at 90 ° C. for 10 minutes to form a back coat layer. See Table 2 for the thickness of the back coat layer. on the other hand,
The following porous layer composition was applied to the opposite surface of each of the seven types of recording paper provided with the back coat layer using a doctor blade, and was then immersed in water at room temperature containing 20% by weight of DMF for 10 minutes to 2 hours.
After immersion for 0 minutes and wet coagulation, by air drying,
Examples 1 and 2 and Comparative Examples 1 to 5 which were fusion-type thermal transfer recording papers having a porous layer on the surface were obtained. The thickness of the porous layer is
It was 20 μm.

[Backcoat layer forming composition] (numerical values indicate parts by weight) Polyester resin 7.43 (Vylon 280, manufactured by Toyobo Co., Ltd.) Antistatic agent 0.07 (Elegan 264, manufactured by NOF Corporation) Antistatic agent 0.37 (manufactured by Sanyo Kasei Co., Chemistat 2500)-Resin fine particles (see Table 1) 2.82-Colorant 0.15 (manufactured by Nippon Kayaku Co., dye)-Toluene 44.58 (solvent)- Methyl ethyl ketone 44.58 (solvent)

[0017]

[Porous layer forming composition] (numerical values indicate parts by weight) ・ Urethane resin 10.79 (Nippon Polyurethane) ・ Vinyl chloride-vinyl acetate resin 2.70 (Nippon Zeon) ・ Pigment ( 1.35 (E-220, manufactured by Nippon Silica Industry Co., Ltd.)-Antistatic agent 0.13 (Elegan 264, manufactured by NOF Corporation)-Fluorescent whitening agent 0.03 (UVITEX-OB, manufactured by Ciba Geigy)・ Dimethylformamide (DMF) 85.00 (solvent)

Next, with respect to Examples 1 and 2 and Comparative Examples 1 to 5 of the melt-type thermal transfer recording paper obtained as described above, a color printer (manufactured by Victor Company of Japan having a thermal head resolution of 300 dots / inch) was used. Trueprin
t 2200). The results are shown in Table 2.

[0020] 1) Actually, the recording paper column shows an example, and the ratio shows a comparative example. 2) The coefficient of friction was measured by a method based on JIS-K7125. μs indicates a static friction coefficient between the porous layer surface and the back coat layer surface of the recording paper, and μk indicates a dynamic friction coefficient between the porous layer surface and the back coat layer surface of the recording paper. 3) Paper feeding / ejecting capability means whether recording paper is fed one by one from the paper feed tray in the printer, and whether paper jams occur in the transport path or paper discharge section of the printer. Say

From the results shown in Table 2, in Comparative Examples 3 to 5, in which the tetrafluoroethylene resin fine particles were not contained in the back coat layer, the average particle diameter φ of the resin fine particles was larger than the pore diameter R of the porous layer, and Even if the thickness is larger than the thickness T of the back coat layer, the paper supply / discharge property is not good. Comparative Examples 1 and 2 contain fine particles of tetrafluoroethylene resin in the back coat layer, and the average particle diameter φ of the fine particles is larger than the pore diameter R of the porous layer and the thickness T of the back coat layer. Since the condition of being larger is not satisfied, the paper feeding / discharging property is not good. Further, in Comparative Examples 1 to 5, both the coefficient of dynamic friction and the coefficient of static friction are large, which causes a sheet feeding failure. On the other hand, the back coat layer contains tetrafluoroethylene resin fine particles, and the average particle diameter φ of the fine particles is larger than the pore diameter R of the porous layer and larger than the thickness T of the back coat layer. 1,2
Can provide good paper supply / discharge properties as recording paper. Also,
Examples 1 and 2 have a dynamic friction coefficient of 0.5 or less and a static friction coefficient of 1.5 or less, and realize an excellent friction coefficient value for obtaining extremely good paper supply / discharge properties.

[0022]

As described above, the fusion type thermal transfer recording paper of the present invention has no transfer of the lubricant to the ink receiving layer and can realize a sufficient paper supply / discharge performance with respect to the printer.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining a fusion-type thermal transfer recording system using one embodiment.

FIG. 2 is a diagram illustrating a configuration of an embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink ribbon 1a Ink layer 1b Ink ribbon base 2 Melt type thermal transfer recording paper 2a Porous layer 2a 'Multi-groove layer 2b Recording paper base 2c Back coat layer 3 Thermal head 4 Platen roller

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-4-232788 (JP, A) JP-A-5-305777 (JP, A) JP-A-6-79845 (JP, A) JP-A-1- 96650 (JP, A) JP-A-6-247068 (JP, A) JP-A-1-228890 (JP, A) JP-A-7-223384 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B41M 5/38-5/40

Claims (1)

(57) [Claims] 1. A fusion-type thermal transfer recording paper having a cushioning ink-receiving layer composed of a porous layer or a multi-grooved layer on one side and a backcoat layer on the other side. Contains tetrafluoroethylene resin fine particles, the pore diameter R of the porous layer is 1 μm or more and 30 μm or less, and the groove width L of the multi-grooved layer is 1 μm or more and 30 μm or less.
Ri, average particle diameter φ of the tetrafluoroethylene resin particles, the larger than the groove width L of the porous layer the pore size R or the multi-grooved porous layer, and the greater than the thickness T of the back coat layer more, J between the backcoat layer and the ink receiving layer surface
Dynamic friction coefficient by the measurement method based on IS-K-7125
Is 0.5 or less, and the coefficient of static friction by the same measuring method
Is 1.5 or less .