JPH08230337A - Thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE: To provide a thermal transfer image receiving sheet made writable on its rear surface side by a pencil or an aq. pen and excellent not only in the feed properties and releasability in a printer but also in blocking resistance and antistaining properties. CONSTITUTION: An image receiving surface is provided on one surface of a base material sheet and a first layer consisting of microsilica and a thermoplastic resin and a second layer composed of cellulose acetate are successively laminated on the other surface of the base material sheet to form a rear surface layer and writing properties and releasability are applied to the rear surface layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving sheet, and more specifically, an image can be formed on the front surface by a thermal transfer method, the back surface can be written with a pencil or a water-based pen, and the transportability in a printer can be improved. The present invention relates to a thermal transfer image-receiving sheet having excellent releasability, blocking resistance, and stain resistance.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods are known. Among them, a sublimable dye is used as a recording agent, and a sublimable dye is used as a thermal transfer sheet by supporting it on a base material sheet such as polyester film. Transferable material that can be dyed, for example,
There has been proposed a method of forming various full-color images on a thermal transfer image-receiving sheet having a dye-receptive layer formed on paper or plastic film.

In this case, a thermal head of a printer is used as a heating means, and a large number of three-color or four-color dots are transferred to a thermal transfer image-receiving sheet by heating for an extremely short time, and the original is formed by the multi-color dots. It reproduces a full-color image. The image formed in this way is
It is very vivid because the coloring material used is a dye,
And because it is excellent in transparency, the obtained image has excellent reproducibility and gradation of intermediate colors, is similar to the image by conventional offset printing or gravure printing, and has a high quality image comparable to a full color photographic image. It can be formed.

[0004]

In order to effectively carry out the above-mentioned thermal transfer method, not only the structure of the thermal transfer sheet but also the structure of the thermal transfer image-receiving sheet for forming an image are important. For example, the conventional thermal transfer image-receiving sheet is
Synthetic paper, plastic film, OHP as its base material
Although a sheet or the like is used, since these base material sheets have a low dye-receptive property, a dye-receptive layer made of a resin having a good dyeing property is formed on the image forming surface. When it is necessary to cut such a thermal transfer image-receiving sheet into a postcard size, form a photographic image of the family on the front side, and write an address on the back side, it is difficult to write on the back side with a pencil or a water-based pen. .

As a method of imparting such writability, conventionally, a hydrophilic filler is used to form a porous layer on the back surface of a thermal transfer image-receiving sheet, or fine irregularities are imparted by a hard filler or a hard resin to form an aqueous pen. A method of imparting writability with a pencil or a pencil is known. However, in the above-mentioned conventional method, the transportability of the thermal transfer image-receiving sheet in the printer and the releasability of the back surface when the front and back of the thermal transfer image-receiving sheet are mistakenly recognized are not taken into consideration, and the problem of double feeding during image formation occurs. appear. Also, blocking may occur when the thermal transfer image receiving sheets are stacked with the image receiving surface and the back surface facing each other,
Further, when the printed matter is stacked with the image receiving surface and the back surface facing each other, there is a problem that the dye migrates from the printed image to the back surface and the back surface is contaminated. Therefore, the object of the present invention is to solve the above-mentioned problems of the conventional art, the back surface of which can be written with a pencil or a water-based pen, and which is excellent in transportability in a printer and releasing property, and further has blocking resistance, It is intended to provide a thermal transfer image-receiving sheet excellent in stain resistance.

[0006]

The above object can be achieved by the present invention described below. That is, the present invention is a back surface layer in which a first layer composed of microsilica and a thermoplastic resin and a second layer composed of cellulose acetate are sequentially laminated on the other surface of the base sheet having an image receiving surface on one surface. And a writing property and a releasability are given to the back surface layer.

[0007]

By sequentially laminating the first layer made of microsilica and a thermoplastic resin and the second layer made of cellulose acetate on the back surface of the thermal transfer image-receiving sheet, the back surface can be written with a pencil or an aqueous pen, and the printer can be used. It is possible to provide a thermal transfer image-receiving sheet which is excellent in internal transportability and releasability, and is also excellent in blocking resistance and stain resistance.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. Examples of the base sheet used in the thermal transfer image-receiving sheet of the present invention include synthetic paper (polyolefin-based, polystyrene-based, etc.), fine paper, art paper,
Coated paper, cast coated paper, wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin internal paper, paperboard, etc., cellulose fiber paper, polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, poly Films or sheets of various plastics such as methacrylate and polycarbonate can be used, and a white opaque film formed by adding a white pigment or a filler to these synthetic resins or a foamed foamed sheet can also be used. Not limited.

Further, a laminated body made of any combination of the above-mentioned substrate sheets can also be used. As an example of a typical laminated body,
Examples include synthetic paper made of cellulose fiber paper and synthetic paper or cellulose fiber paper and plastic film or sheet. The thickness of these substrate sheets may be arbitrary, for example,
The thickness is generally about 10 to 300 μm. When the substrate sheet as described above has poor adhesion to the low-elasticity resin layer, it is preferable to subject its surface to primer treatment or corona discharge treatment.

In the present invention, the back surface layer is formed on the surface of the base sheet opposite to the image forming surface. This back surface layer is formed by sequentially laminating a first layer made of microsilica and a thermoplastic resin and a second layer made of cellulose acetate. The microsilica used in the present invention forms minute irregularities on the back surface of the thermal transfer image-receiving sheet to impart pencil writability, and the -SiOH group (hydrophilic group) that the microsilica surface has.
The purpose is to impart writing properties with a water-based pen and adhesion to stamps. First, with regard to the above-mentioned minute uneven shape, the degree of the minute uneven shape formed is determined by the average particle diameter of the microsilica. That is, if the particle size is too small, a sufficient minute uneven shape cannot be obtained, and if the particle size is too large, the surface friction characteristics are affected and proper slipperiness cannot be obtained. Therefore, the average particle size of the microsilica used in the present invention is preferably 1 to 10 μm.

Next, -SiO which micro silica has on the surface
Regarding the H group, there are some microsilicas that have been surface-treated for the purpose of imparting hydrophobicity to the -SiOH group in order to improve suitability for coating, but the microsilica used in the present invention imparts hydrophilicity. For this purpose, it is preferable to use untreated microsilica. Further, in order that the microsilica has higher hydrophilicity, it is preferable that the specific surface area of the microsilica is large, and for example, the specific surface area by the BET method is preferably 20 m ² / g or more.
In addition, microsilica has an effect of preventing blocking. As such a micro silica, trade name P-7
3: Specific surface area 300 to 350, average particle diameter 3.0 ± 0.
5, trade name P-801: specific surface area 100 to 150, average particle size 2.8 ± 0.5, trade name P-527: specific surface area 30
˜60, average particle size 1.8 ± 0.3, and the like.

As the thermoplastic resin used as the binder of microsilica, polyurethane resin, polyester resin, polyvinyl acetate resin, polyvinyl acetal resin, polyvinyl butyral resin, cellulose plastic, polyolefin resin, acrylic resin and the like are used, and particularly, Not limited. As the amount of the above-mentioned microsilica and resin used, the ratio of microsilica / thermoplastic resin is preferably in the range of 0.1 to 3.0. If the proportion of microsilica used is too low, the writability with an aqueous pen is insufficient. On the other hand, if the proportion used is too high, proper slipperiness cannot be obtained, and so on.

Although the above are the essential components of the first layer of the back surface layer, a white pigment or a fluorescent whitening agent may be added for the purpose of increasing the whiteness of the back surface layer, and if necessary, a colorant. Etc. can also be added. Regarding whiteness, a layer containing a white pigment may be formed on the surface of the base material sheet before forming the back surface layer. In particular, by including a nylon filler in this first layer, the transportability of the thermal transfer image-receiving sheet in the printer can be improved. The nylon filler preferably has a molecular weight of 100,000 to 900,000 and is spherical, and has an average particle diameter of 0.01 to 30 μm, and particularly preferably has a molecular weight of 100,000 to 500,000 and an average particle diameter of 0.1.
It is more preferably from 01 to 10 μm. Further, as the type of nylon filler, nylon 12 filler is more preferable than nylon 6 and nylon 66 because it has excellent water resistance and does not change in characteristics due to water absorption.

Nylon fillers have a high melting point, are thermally stable, and have good oil resistance, chemical resistance, etc., and therefore are difficult to be dyed with a dye. Further, it has self-lubricating property, has a low friction coefficient, and when the molecular weight is 100,000 to 900,000, it is hardly worn and the mating material is not damaged. Further, a preferable average particle diameter is 0.1 to 30 μm when used for a thermal transfer image receiving sheet for a reflection image, and 0.01 to 1 μm when used for a thermal transfer image receiving sheet for a transmission image.
If the particle size is too small, the filler is hidden in the slippery back surface layer, and does not perform the function of sufficient slipperiness, and if the particle size is too large, the protrusion from the slippery back surface layer becomes large, resulting It is not preferable because the friction coefficient is increased and the filler is lost.

The blending ratio of the nylon filler to the thermoplastic resin is preferably in the range of 0.01 to 200% by weight. When used in a thermal transfer image-receiving sheet for a reflection image, 1 to 100% by weight is more preferable, and in the case of a thermal transfer image-receiving sheet for a transmission image, 0.05 to 2% by weight is more preferable. If the blending ratio of the nylon filler is less than 0.01% by weight, the slipperiness of the back surface layer will be insufficient, causing problems such as paper jams. On the other hand, if it exceeds 200% by weight, it is not preferable because it is too slippery and causes troubles such as color shift on the printed screen.

The first layer is a solution or dispersion prepared by dissolving and dispersing microsilica and a thermoplastic resin in a suitable organic solvent or water, and further, for example, a gravure printing method, a screen printing method, It is formed by applying and drying by a forming means such as a reverse roll coating method using a gravure plate. Its thickness is generally 0.2 to 20 μm. Incidentally, in forming the above-mentioned first layer, by adding a crosslinking agent such as a polyisocyanate or a chelating agent in the coating liquid,
By making the formed layer a crosslinked product, the solvent resistance and film strength of the film can be further improved.

In the present invention, a second layer made of cellulose acetate is formed on the surface of the first layer. This means that when the first layer is on the outermost surface, the surface friction characteristics and releasability required cannot be obtained on that surface, and by forming the second layer, it is necessary for the back surface layer. Provides surface friction characteristics and releasability. By using cellulose acetate for the formation of the second layer, the thermal transfer image-receiving sheet is provided with appropriate releasability, stain resistance, and surface friction characteristics, and even if the front and back are improperly printed, abnormal transfer will occur. It can be prevented, and blocking resistance can be imparted. Cellulose acetate is
Since the solubility and releasability in a solvent vary depending on the degree of acetylation and the degree of polymerization, the solubility of the solvent is good in the range of 40 to 60%, and the degree of polymerization is 100 to 30.
The range of 0 is preferable. If the degree of polymerization is too low, the releasability decreases, and if the degree of polymerization is too high, processability (solvent solubility)
Is reduced, which is not preferable.

The second layer is a solution of cellulose acetate and necessary additives dissolved / dispersed in an appropriate organic solvent or water.
The dispersion is applied and dried by a forming means such as a gravure printing method, a screen printing method, and a reverse roll coating method using a gravure plate to form the dispersion. By forming such a second layer, suitable back surface layer friction characteristics and releasability are obtained, transportability in the printer is improved, blocking resistance is improved, and further when printed matter is stacked. At the same time, the set-off problem that the dye forming the image is transferred to the back surface layer to stain the back surface layer is solved. The thickness of the second layer is preferably 0.01 to 1.0 μm. When the thickness is less than 0.01 μm, the above properties, particularly releasability cannot be obtained, and when the thickness exceeds 1.0 μm, the surface of the back surface layer becomes smooth and the writing provided by microsilica in the first layer. And stickiness of stamps are reduced.

In the present invention, when the thermal transfer image-receiving sheet of the present invention is used as a sublimation transfer type image-receiving sheet, an intermediate layer made of an elastic resin such as polyurethane resin is optionally formed on the other surface of the above-mentioned substrate sheet. To form a dye receiving layer for the sublimable dye. Examples of the resin forming the intermediate layer include chlorinated polypropylene, acrylic resin, vinyl chloride / vinyl acetate copolymer resin, polyurethane resin, ethylene / vinyl acetate copolymer resin, acrylic modified ionomer resin and the like. The intermediate layer is a dispersion of the resin dissolved in an appropriate organic solvent or dispersed in an organic solvent or water, for example, a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, etc. It is formed by applying and drying by means. Its thickness is generally 0.5-10.0 μm.

Further, the dye receiving layer is for receiving the sublimable dye transferred from the thermal transfer sheet and maintaining the formed image, and as the resin for forming the dye receiving layer, for example, Polyolefin resin such as polypropylene, halogenated polymer such as polyvinyl chloride and polyvinylidene chloride, vinyl polymer such as polyvinyl acetate and polyacrylic ester, polyester resin such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resin, polyamide Resins, copolymer resins of olefins such as ethylene and propylene with other vinyl monomers, ionomers, cellulosic resins such as cellulose diacetate, polycarbonates, etc., and particularly preferable ones are vinyl resins and polyester resins. Is. In forming the dye receiving layer, pigments or fillers such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate, fine powder silica, etc. are used for the purpose of improving the whiteness of the dye receiving layer and further improving the sharpness of the transferred image. Agents can be added.

The above-mentioned dye-receptive layer is prepared by dissolving the above resin with necessary additives such as a releasing agent and a crosslinking agent in an appropriate organic solvent or dispersing it in an organic solvent or water. The body, for example, gravure printing, screen printing,
A dye receiving layer is formed by coating and drying by a forming means such as a reverse roll coating method using a gravure plate. The dye receiving layer formed as described above may have any thickness, but it is generally 1 to 50 μm thick. Further, such a dye receiving layer is preferably a continuous coating, but it may be formed as a discontinuous coating by using a resin emulsion or a resin dispersion.

Further, the thermal transfer image-receiving sheet of the present invention may be provided with a detection mark. The detection mark is extremely convenient when positioning the thermal transfer sheet and the thermal transfer image receiving sheet, and for example, a detection mark that can be detected by a photoelectric tube detection device can be provided on the other surface of the thermal transfer image receiving sheet by printing or the like. . The sublimation type thermal transfer sheet used when performing thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is one in which a dye layer containing a sublimable dye is provided on a paper or a polyester film, which is conventionally known. Any thermal transfer sheet can be used as it is in the present invention.

Further, as the means for applying the thermal energy during the thermal transfer, any conventionally known applying means can be used.
By controlling the recording time with a recording device such as a thermal printer (for example, video printer VY-100 manufactured by Hitachi, Ltd.), 5 to 100 mJ / m
The intended purpose can be sufficiently achieved by applying thermal energy of about m ² .

[0024]

EXAMPLES Next, the present invention will be described more specifically with reference to Reference Examples, Examples and Comparative Examples. In the text, parts and% are based on weight unless otherwise specified. Reference Example 1 Synthetic paper (Yupo FPG150, thickness 1
50 μm), one side of which is coated with an ink for an intermediate layer having the following composition by a roll coating method at a ratio of 2.0 μm when dried, and then the following ink for a dye receiving layer is dried. At that time, it was coated by a roll coating method at a rate of 4 μm, immediately dried briefly with a dryer, and then dried in an oven at 120 ° C. for 5 minutes to form a dye receiving layer to obtain a thermal transfer image receiving sheet.

Ink for intermediate layer : Polyurethane resin (N5199, manufactured by Nippon Polyurethane Industry) 50 parts Titanium oxide (TCA-888, manufactured by Tochem Products) 50 parts Methyl ethyl ketone / toluene (1: 1) 400 parts Ink for dye receiving layer Chloride Vinyl-vinyl acetate copolymer (# 1000A, manufactured by Denki Kagaku Kogyo) 75 parts Polyester resin (Toyobo, Byron 600) 25 parts Catalyst curable silicone (X62-1212 manufactured by Shin-Etsu Chemical Co., Ltd.) 6 parts Platinum catalyst (Shin-Etsu Chemical) Industrial, PL-50T) 3 parts Methyl ethyl ketone / toluene (1: 1) 400 parts

Example 1 Reference example 1 was formed on the back surface of the thermal transfer image-receiving sheet in reference example 1.
With the same coating method as in,
A single layer and a second layer are formed to obtain the thermal transfer image-receiving sheet of the present invention.
Was.Ink for the first layer (Thickness 2.0 μm) Polyurethane resin (HMS-20, manufactured by Nippon Polyurethane Industry) 50 parts Micro silica (P-73, manufactured by Mizusawa Chemical Industry) 50 parts Methyl ethyl ketone / toluene (1: 1) 400 parts Ink for the second layer (Thickness 0.4 μm) Cellulose acetate (L-40, manufactured by Daicel Chemical Industries) 100 parts Methyl ethyl ketone 900 parts

Example 2 The following ink was used in place of each ink in Example 1.
In the same manner as in Example 1 except for the above, the thermal transfer image receiving sheet of the present invention is used.
Got A white layer is formed before the first and second layers are formed.
did.Ink for white layer (1.0 μm) Polyurethane resin (N5199, manufactured by Nippon Polyurethane Industry) 50 parts Titanium oxide (TCA-888, manufactured by Tochem Products) 50 parts Methyl ethyl ketone / toluene (1: 1) 400 parts Ink for the first layer (Thickness 2.0 μm) Polyurethane resin (HMS-20, manufactured by Nippon Polyurethane Industry) 50 parts Micro silica (P-73, manufactured by Mizusawa Chemical Industry) 50 parts Methyl ethyl ketone / toluene (1: 1) 400 partsInk for the second layer (Thickness 0.3 μm) Cellulose acetate (L-30, manufactured by Daicel Chemical Industries, Ltd.) 100 parts Methyl ethyl ketone 900 parts

Example 3 A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that the following ink was used in place of each ink in Example 1. Ink for first layer (thickness 3.0 μm) Polyurethane resin (N5199, manufactured by Nippon Polyurethane Industry) 40 parts Micro silica (P-801, manufactured by Mizusawa Chemical Industry) 50 parts Isocyanate (Takenate D-160N, manufactured by Takeda Chemical Industries) 10 Parts Methyl ethyl ketone / toluene (1: 1) 400 parts Second layer ink (thickness 0.4 μm) Cellulose acetate (L-30, manufactured by Daicel Chemical Industries) 100 parts Methyl ethyl ketone 900 parts

Example 4 A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that the following ink was used in place of each ink in Example 1. Ink for the first layer (thickness 2.5 μm) Polyvinyl butyral (# 3000-1, manufactured by Denki Kagaku Kogyo) 30 parts Micro silica (P-527, manufactured by Mizusawa Chemical Co., Ltd.) 60 parts Nylon filler (MW-330, Shinto paint) 10 parts Methyl ethyl ketone / toluene (1: 1) 900 parts Second layer ink (thickness 0.5 μm) Cellulose acetate (L-40, manufactured by Daicel Chemical Industries) 100 parts Methyl ethyl ketone 900 parts

Example 5 A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that the following ink was used in place of each ink in Example 1. Ink for the first layer (thickness 3.5 μm) Polyvinyl butyral (# 5000A, manufactured by Denki Kagaku Kogyo) 30 parts Micro silica (P-527, manufactured by Mizusawa Chemical Co., Ltd.) 60 parts Nylon filler (MW-330, manufactured by Shinto Paint Co., Ltd.) 10 parts Methyl ethyl ketone / toluene (1: 1) 900 parts Ink for second layer (thickness 0.5 μm) Cellulose acetate (L-40, manufactured by Daicel Chemical Industries) 100 parts Methyl ethyl ketone 900 parts

Comparative Example 1 A thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that the following ink was used in place of each ink in Example 1. First layer ink (thickness 2.0 .mu.m) polyurethane resin (HMS-20, manufactured by Nippon Polyurethane Industry Co.) 50 parts microsilica (P-73, Mizusawa Chemical Industries, Ltd.) 50 parts Methyl ethyl ketone / toluene (1: 1) 400 Part No ink formation for two layers

Tests and Results The thermal transfer image-receiving sheets of Examples 1 to 5 and Comparative Example 1 prepared as described above were tested for the following items. The results are shown in Table 1. (1) Writability Characters and the like were written on the sample (back side) with a pencil and a water-based pen, and the writability was evaluated. ◯ ... Both pencils and water-based pens show good writability. B: Both pencils and water-based pens can be written, but there are problems such as poor fixability. ×: Both the pencil and / or the water-based pen have no writability at all.

(2) Releasability A gradation pattern was printed on a sample (rear surface) using a thermal transfer sheet using a cyan dye, and the degree of heat fusion between the sample and the thermal transfer sheet was evaluated. ◯: No heat fusion, and light peeling. Δ: There is almost no heat fusion, but peeling is heavy. ×: There is a portion where the sample and the thermal transfer sheet are not separated due to heat fusion. (3) Surface Friction Characteristics Printing was performed continuously with a printer, and the number of printed sheets was evaluated by the number of sheets in which double feeding occurred. ○: No troubles such as double feeding occur. △: 1 to 5 out of 50 problems such as double feeding occurred. ×: Six or more out of 50 problems such as double feeding occurred.

(4) Contamination resistance A thermal sublimation transfer printer (VY-
50 Hitachi, Ltd.), and a gradation pattern was printed using a thermal transfer sheet using yellow, magenta and cyan dyes. Using this as a sample, each cut into a size of 14 x 4 cm, the print screen and the back surface are overlapped, sandwiched between smooth metal plates, and a load of 1.5 kg is applied from above and left in an oven at 50 ° C for 7 days. did. Then, the sample was taken out and the dye transfer to the back surface was observed. ○: Almost no migration of dye is observed. △: Transfer of dye is recognized depending on the color. ×: Transfer of dye is observed regardless of color. Almost no migration of dye is observed.

Table 1

[0036]

[Effects] According to the present invention as described above, a back surface of a thermal transfer image-receiving sheet is sequentially laminated with a first layer made of microsilica and a thermoplastic resin and a second layer made of cellulose acetate, so that the back surface is made of pencil or pencil. It is possible to provide a thermal transfer image-receiving sheet which can be written with an aqueous pen, has excellent transportability in a printer and releasability, and has excellent blocking resistance and stain resistance.

Claims (10)

[Claims] 1. A back surface layer obtained by sequentially laminating a first layer composed of microsilica and a thermoplastic resin and a second layer composed of cellulose acetate on the other surface of a base sheet having an image receiving surface on one surface. A thermal transfer image-receiving sheet characterized in that the backside layer is provided with writability and releasability. 2. The thermal transfer image-receiving sheet according to claim 1, wherein the first layer is a layer cured by a curing agent. 3. The thermal transfer image-receiving sheet according to claim 1, wherein the curing agent is polyisocyanate or a chelating agent. 4. The thermal transfer image-receiving sheet according to claim 1, wherein the first layer contains a nylon filler. 5. The thermal transfer image-receiving sheet according to claim 1, which has a white intermediate layer between the base sheet and the first layer. 6. The average particle size of microsilica is 1 to 10 μm.
The thermal transfer image-receiving sheet according to claim 1, which is m. 7. The thermal transfer image-receiving sheet according to claim 1, wherein the second layer has a thickness of 0.01 to 1.0 μm. 8. The thermal transfer image-receiving sheet according to claim 1, wherein the microsilica / thermoplastic resin ratio of the first layer is 0.1 to 3.0. 9. The thermal transfer image-receiving sheet according to claim 1, wherein a dye-receiving layer dyed with a sublimable dye is formed on the image-receiving surface. 10. The thermal transfer image-receiving sheet according to claim 1, which has a postcard shape.