JP2021074950A - Image receiving sheet for sublimation transfer - Google Patents

Abstract

To provide an image receiving sheet for sublimation transfer which has a uniform image quality and can obtain sufficient maximum concentration.SOLUTION: The image receiving sheet for sublimation transfer has resin layers 3 on both surfaces of a base material 2 and at least a heat insulating layer 4 and a dye receiving layer 5 from a side closer to the base material on one or both surfaces provided with the resin layers of the base material. Thermal conductivity of the resin layer on a side where the heat insulating layer is provided is 0.15 W/(mK) or less, and a maximum valley depth of a waviness curve measured from the surface of the resin layer on a side where the heat insulating layer is provided (JISB0601:2013) Wv [unit: μm] is 1.5 μm or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image receiving sheet for sublimation transfer.

Generally, the thermal transfer recording medium is an ink ribbon called a so-called thermal ribbon used in a thermal transfer printer. This ink ribbon includes, for example, a base material, a thermal transfer layer containing ink provided on one surface of the base material, and a heat-resistant slipping layer (backcoat layer) provided on the other side of the base material. , Equipped with. In a thermal transfer printer, the heat generated by the thermal head is applied to the thermal transfer layer of the ink ribbon to sublimate (sublimate transfer method) or melt (melt transfer method) the ink contained in the thermal transfer layer, and the ink is subjected to thermal transfer image reception. It is transferred to a sheet, and a film made of ink is formed on the thermal transfer image receiving sheet. Characters and images are formed on the heat transfer image receiving sheet by the film made of this ink. The thermal transfer image receiving sheet generally has a structure in which an image receiving layer of sublimation ink or molten ink is provided on a base material such as paper, and various resin layers or the like may be provided as needed.

Among thermal transfer printers, sublimation transfer printers can easily form various images in full color due to the advanced functionality of the printer, so self-printing of digital cameras, printing of cards such as identification cards, and output for amusement. It is widely used for printing things. With the diversification of such thermal transfer printers, there is a demand for miniaturization, high speed and low cost of printers, and durability of the obtained printed matter. In addition, the spread of smartphones has increased the demand for photographic prints at home, the shipment of small sheet-fed printers for home use has increased, and sublimation transfer consisting of ink ribbons for sheet-fed and image-receiving sheets for sublimation transfer has increased. Recording media for printing are also widespread.

Under such circumstances, the cost reduction of media is required with the diversification and widespread use of sublimation transfer printers. In order to reduce the cost of media, it is required to sufficiently develop color even if an inexpensive general-purpose dye is used.

As a method of obtaining sufficient color development using an inexpensive general-purpose dye, for example, as in Patent Document 1, by providing a heat insulating layer on the image receiving sheet for sublimation transfer, the thermal conductivity of the heat insulating layer is lowered, and the surface of the dye receiving layer is reduced. It has been proposed to raise the temperature of the dye to improve the color development characteristics. Although it is possible to improve the color development characteristics with the heat insulating layer, a suitable thickness is required to secure the thermal conductivity only with the heat insulating layer, which in turn leads to an increase in the cost of the recording medium for sublimation transfer. It is desired to improve the color development characteristics after making the layer as thin as possible.

Further, in sublimation printing, the smoothness of the surface of the sublimation transfer recording medium (ink ribbon and sublimation transfer image receiving sheet) is also important. Due to the nature of sublimation printing, the unevenness of the recording medium for sublimation transfer affects the local print density and greatly affects the image quality, so it is necessary to maintain the smoothness of the surface. Various indexes of smoothness are defined. For example, Patent Document 2 discloses an example using SRa.

In order to ensure the smoothness of the surface of the recording medium for sublimation transfer, it is important to maintain the smoothness of each layer, and in particular, maintain the smoothness of the surface of the resin layer between the paper substrate of the image receiving sheet for sublimation transfer and the heat insulating layer. It is important to do.

International Publication No. 2008/129715 Japanese Unexamined Patent Publication No. 2011-16295

The present invention has been made in view of the above problems, and an object of the present invention is to provide an image receiving sheet for sublimation transfer, which can obtain a uniform image quality and a sufficient maximum density even if the heat insulating layer is thinned. To do.

The inventors have found that the above problems can be achieved by using not only the hollow particles but also the thermal conductivity of the binder for controlling the thermal conductivity of the resin layer in the image receiving sheet for sublimation transfer, and complete the present invention. It came to.

In order to solve the above problems, in the invention according to claim 1, resin layers are provided on both sides of paper as a base material, and a heat insulating layer and a dye are provided on one or both surfaces of the resin layer in order from the side closer to the base material. An image receiving sheet for sublimation transfer provided with at least a receiving layer, the resin layer on the side provided with the heat insulating layer has a thermal conductivity of 0.15 W / (mK) or less, and a waviness curve measured from the surface of the resin layer. This is an image receiving sheet for sublimation transfer, characterized in that the maximum valley depth (JISB0601: 2013) Wv [unit: μm] is 1.5 μm or less.

The invention according to claim 2 is characterized in that the heat insulating layer is made of a film containing voids.

The invention according to claim 3 is characterized in that the film containing the above-mentioned voids contains at least polypropylene.

The invention according to claim 4 is characterized in that the film containing the voids contains at least a polyester resin.

The invention according to claim 5 is characterized in that the heat insulating layer is made of at least a pigment and a resin.

The invention according to claim 6 is characterized in that the pigment is composed of hollow particles.

The invention according to claim 7 is characterized in that the hollow particles in the first half of the period are crosslinked acrylic-styrene copolymers.

According to the present invention, it is possible to maintain a uniform image quality and obtain a sufficient maximum density even if the heat insulating layer is thinned.

It is sectional drawing which shows typically the image-receiving sheet for sublimation transfer which concerns on embodiment of this invention.

An embodiment of the image receiving sheet for sublimation transfer of the present invention will be described.
It should be noted that the present embodiment is specifically described in order to better understand the gist of the invention, and is not limited to the present invention unless otherwise specified.

[Image receiving sheet for sublimation transfer]
FIG. 1 is a cross-sectional view schematically showing an image receiving sheet for sublimation transfer according to an embodiment of the present invention. The image receiving sheet 1 for sublimation transfer according to the present embodiment includes a base material 2, a resin layer 3 provided on both sides thereof, a heat insulating layer 4 and a dye receiving layer 5 which are sequentially laminated on one surface of the resin layer 3. Be prepared.

The base material 2 is not particularly limited, and conventionally known ones are used. Examples of the base material 2 include condenser paper, glassin paper, sulfate paper, high-sized paper, synthetic paper (dioxide-based, polystyrene-based), high-quality paper, art paper, coated paper, resin-coated paper, cast-coated paper, and the like. Examples include wallpaper, backing paper, synthetic resin or emulsion impregnated paper, synthetic rubber latex impregnated paper, synthetic resin inner paper, paperboard, etc., cellulose fiber paper, etc., but from the viewpoint of material cost, high quality paper, coated paper, etc. are used. It is desirable to use it. As the base material 2, one kind of these synthetic papers or papers may be used alone, or two or more kinds may be used in combination as a composite.

The thickness of the base material 2 is preferably 25 μm or more and 250 μm or less, and more preferably 50 μm or more and 200 μm or less.
When the thickness of the base material 2 is within the above range, the elasticity, strength and heat resistance required for the printed matter can be sufficiently obtained when the printed matter is formed.

When the resin layer 3 is provided on the base material 2, the surface of the resin layer 3 is made smooth (waviness maximum valley depth (JISB0601: 2013) Wv is 1.5 μm or less, more preferably 1.3 μm or less. (Achievement) and the addition of elasticity to the heat transfer image receiving sheet, which is insufficient with the paper base material alone, are required. It is also required that the dye receiving layer 5 does not transfer the dye received by transfer to the base material 2.

Therefore, examples of the material of the resin layer 3 include low-density polyethylene resin, high-density polyethylene, resin, acrylic resin, polypropylene resin, polycarbonate resin, urethane resin, vinyl chloride resin, ethylene / vinyl acetate copolymer resin, and the like. The present invention is not limited to this, and a mixture of resins and additives may be added.

Further, the thickness of the resin layer 3 can be appropriately changed depending on the smoothness of the base material 2, but if the resin layer 3 is thicker than the thickness of the base material 2, the texture of the paper is lost and the material cost increases. Therefore, it is desirable to keep the thickness in the range of 10 μm to the thickness of the base material 2 or less.

The heat insulating layer 4 in the present invention has a heat insulating property capable of preventing the heat applied during image formation by thermal transfer from being lost due to heat transfer to the base material 2 and the like.
The heat insulating layer 4 provided on the surface of one of the resin layers 3 can be a conventionally known one, and can be a pigment, particularly a pigment composed of hollow particles and a binder resin, a foamed polypropylene film or a foamed polyethylene. Examples thereof include a heat insulating layer using a film having voids inside, such as a foamed film such as terephthalate, and a composite film having a skin layer which is a smooth layer on one side or both sides of the foamed film. As the hollow particles, for example, those made by cross-linking an acrylic-styrene copolymer can be used. However, as the heat insulating layer using a foamed film or the like, it is preferable to use a heat insulating layer using hollow particles in consideration of cost and the tendency for curling to occur in the bonding process with the base material.

In addition, the thermal conductivity of the binder resin is preferably 0.15 W / (mK) or less. If the thermal conductivity is higher than this, it becomes difficult to obtain a sufficient maximum concentration.

The dye receiving layer 5 receives the sublimating dye transferred from the ink ribbon at the time of image formation by thermal transfer, and holds the received sublimating dye in the receiving layer to form an image on the surface of the dye receiving layer 5. And can be maintained. The dye receiving layer 5 may further contain a mold release agent, a filler, and the like in addition to the binder resin.
As the binder resin, acrylic resin, vinyl chloride resin, polyolefin resin such as polyethylene and polypropylene, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer (salt vinegar vinyl resin), halogenation of polyvinylidene chloride and the like. Polymers, polyvinyl acetate / acrylic copolymers, vinyl polymers such as polyacrylic acid esters, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene with other vinyl monomers, ionomers, cellulose di Examples thereof include cellulose-based resins such as acetate, polycarbonate and the like, and mixed systems of these resins, but the present invention is not limited thereto. It is preferably a vinyl chloride resin, and among the vinyl chloride resins, at least one vinyl chloride resin selected from a vinyl chloride / vinyl acetate copolymer and a vinyl chloride / acrylic copolymer is more preferable. ..

The dye receiving layer 5 may also contain a curing agent. As an example, if it is a polyisocyanate, a conventionally known one can be used.
The content of polyisocyanate is preferably 0.3 to 1.5 times equivalent or less with respect to the acid value of the resin. If the equivalent is less than 0.3 times, there is a risk that a sufficient addition effect cannot be obtained. Further, when the equivalent is larger than 1.5 times, the releasability is improved, but there is a high possibility that transfer failure or concentration decrease of the overcoat layer will occur.

Examples of the release agent include silicone oil, a fluorine-based additive, and an organic wax, and silicone oil is particularly preferable because it is easy to use.

Silicone oils include amino-modified silicones, alcohol-modified silicones, vinyl-modified silicones, urethane-modified silicones, epoxy-modified silicones, polyester-modified silicones, polyether-modified silicones, polyester-modified silicones, acrylic-modified silicones, aralkyl-modified silicones, and amide-modified silicones. Silicone oil can be mentioned, but is not limited to this. In the present invention, these can be mixed or polymerized using various reactions before use.

Examples of the filler include silica fine particles (coroidal silica, fumed silica, etc., regardless of manufacturing method), alumina fine particles, polyethylene beads, polypropylene beads, etc., but the particle size is not limited to 2 μm as secondary particles. Hereinafter, the primary particles are preferably 500 nm or less.

The thickness of the dye receiving layer 5 is preferably 0.1 μm or more and 10 μm or less, and more preferably 0.5 μm or more and 8 μm or less.

When the thickness of the dye receiving layer 5 is 0.1 μm or more, sufficient mechanical strength can be obtained for the dye receiving layer 5, so that poor image quality is less likely to occur. On the other hand, when the thickness of the dye receiving layer 5 is 10 μm or less, it is possible to prevent surface defects such as cracks.

Further, in the image receiving sheet 1 for sublimation transfer of the present embodiment, an adhesive layer may be provided between the resin layer 3 and the heat insulating layer 4 in order to improve the adhesiveness between the resin layer 3 and the heat insulating layer 4.
The material for forming the adhesive layer is not particularly limited, and conventionally known materials are used. Examples of the material for forming the adhesive layer include polyolefin resins such as polyethylene, urethane resins, acrylic resins, polyester resins and the like. Among these, urethane-based resin and acrylic-based resin are preferable.

Further, in the sublimation transfer image receiving sheet 1 in which the dye receiving layer 5 is installed on only one side in the present embodiment, the resin layer 3 on the side of the base material 2 opposite to the side on which the dye receiving layer 5 is provided is placed. A back surface layer may be provided.
This back surface layer is provided to improve printer transportability, prevent blocking with the dye receiving layer 5, and prevent curling of the image receiving sheet 1 for sublimation transfer before and after printing.

The material for forming the back surface layer is not particularly limited, and conventionally known materials are used. Examples of the material forming the back surface layer include polyolefin resins such as polyethylene resin and polypropylene resin, acrylic resins, polycarbonate resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyester resins, polystyrene resins, and binder resins such as polyamide. And so on.
Further, a known additive such as a filler or an antistatic agent may be added to the material forming the back surface layer, if necessary.

Further, the sublimation transfer image receiving sheet 1 of the present embodiment is provided with an undercoat layer between the heat insulating layer 4 and the dye receiving layer 5 as long as the performance of the sublimation transfer image receiving sheet 1 of the present embodiment is not impaired. May be.

The thickness of the undercoat layer is preferably 0.1 μm or more and 6 μm or less, and more preferably 0.2 μm or more and 5 μm or less.
When the thickness of the undercoat layer is 0.1 μm or more, not only the film thickness of the undercoat layer can be easily adjusted, but also the print density is unlikely to vary. Further, the adhesion between the undercoat layer, the heat insulating layer 4 and the dye receiving layer 5 becomes sufficient. On the other hand, when the thickness of the undercoat layer is 6 μm or less, the printing density at the time of high-speed printing does not decrease. Further, from the viewpoint of cost, the thickness of the undercoat layer is preferably 6 μm or less.

As the resin used for the undercoat layer, conventionally known resins can be used, and examples thereof include gelatin, polyvinyl alcohol, acrylic, polyester, styrene-butadiene latex, and polyvinylpyrrolidone.

According to the image receiving sheet 1 for sublimation transfer of the present embodiment, it is possible to obtain a sufficient maximum concentration even in a media configuration using a general-purpose dye.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.
The term "part" in the text is based on mass unless otherwise specified.

[Example 1]
A high-quality paper having a thickness of 140 μm was used as a base material, and a first polypropylene resin layer having a thickness of 30 μm was formed as a resin layer on one surface by a melt extrusion method so that the Wv of the surface was 1.4 μm. .. Further, a second polyethylene resin layer having a thickness of 40 μm was formed as a resin layer on the other surface of the woodfree paper by a melt extrusion method.

Next, the heat insulating layer coating liquid 1 having the following composition is applied onto the first polypropylene resin layer so that the thickness after drying is 25 μm to form a coating film, and the coating film is dried. As a result, a heat insulating layer was formed.

"Insulation layer coating liquid 1"
Hollow particles (trade name: LaTeX SN-1055, hollow ratio: 55%): 58.5 parts Natural rubber (LATEX LA): 29.5 parts Pure water: 12.0 parts

Then, a dye receiving layer coating liquid a having the following composition is applied onto the heat insulating layer so that the thickness after drying is 3 μm to form a coating film, and the coating film is dried to obtain a dye. A receiving layer was formed, and an image receiving sheet for sublimation transfer of Example 1 was obtained.

"Dye receiving layer coating liquid a"
Vinyl chloride / vinyl acetate modified resin (trade name: Solvine C (manufactured by Nisshin Chemical Industry Co., Ltd.): 60.0 parts by mass Silicone oil release agent (trade name: KF868): 0.09 parts by mass Methyl ethyl ketone: 140. 0 parts by mass

[Example 2]
An image receiving sheet for sublimation transfer of Example 2 was obtained in the same manner as in Example 1 except that the Wv of the first polypropylene resin layer was 1.1 μm.

[Example 3]
An image receiving sheet for sublimation transfer of Example 3 was obtained in the same manner as in Example 1 except that the Wv of the first polypropylene resin layer was 1.5 μm.

[Example 4]
An image receiving sheet for sublimation transfer of Example 4 was obtained in the same manner as in Example 1 except that the thickness of the heat insulating layer after drying was 30 μm.

[Example 5]
An image receiving sheet for sublimation transfer of Example 5 was obtained in the same manner as in Example 1 except that the heat insulating layer was a foamed polypropylene film having a thickness of 30 μm.

[Example 6]
An image receiving sheet for sublimation transfer of Example 6 was obtained in the same manner as in Example 1 except that the heat insulating layer was a foamed polypropylene film having a thickness of 40 μm.

[Comparative Example 1]
A high-quality paper having a thickness of 140 μm was used as a base material, and a first polyethylene resin layer having a thickness of 30 μm was formed as a resin layer on one surface by a melt extrusion method so that the Wv of the surface was 1.4 μm. .. Further, a second polyethylene resin layer having a thickness of 40 μm was formed as a resin layer on the other surface of the woodfree paper by a melt extrusion method.

Next, the heat insulating layer coating liquid 1 is applied onto the first polyethylene resin layer so that the thickness after drying is 25 μm to form a coating film, and the coating film is dried to insulate. A layer was formed.

Then, a dye receiving layer coating liquid a having the following composition is applied onto the heat insulating layer so that the thickness after drying is 3 μm to form a coating film, and the coating film is dried to obtain a dye. A receiving layer was formed, and an image receiving sheet for sublimation transfer of Comparative Example 1 was obtained.

"Dye receiving layer coating liquid a"
Vinyl chloride / vinyl acetate modified resin (trade name: Solvine C (manufactured by Nisshin Chemical Industry Co., Ltd.): 60.0 parts by mass Silicone oil release agent (trade name: KF868): 0.09 parts by mass Methyl ethyl ketone: 140. 0 parts by mass

[Comparative Example 2]
An image receiving sheet for sublimation transfer of Comparative Example 2 was obtained in the same manner as in Example 1 except that the Wv of the first polypropylene resin layer was 1.7 μm.

[Preparation of test transfer recording medium]
A polyethylene terephthalate film with a single-sided easy-adhesion treatment having a thickness of 4.5 μm was used as a base material, and a heat-resistant slip layer coating liquid having the following composition was applied to the non-easy-adhesion-treated surface, and the amount applied after drying was 1.0 g / It ^{was applied and dried to a thickness of m 2} to obtain a base material with a heat-resistant slippery layer.
Next, a thermal transfer layer coating liquid having the following composition is applied to the easily adhesive-treated surface of the base material with a heat-resistant slipping layer so that the coating amount after drying is 1.0 g / m ^2, and the thermal transfer layer is dried. Was formed to obtain a thermal transfer recording medium.

"Heat-resistant slip layer coating liquid"
Silicone acrylic graft polymer (trade name: US-350, manufactured by Toagosei Co., Ltd.): 50.0 parts by mass Methyl ethyl ketone: 50.0 parts by mass

"Thermal transfer layer coating liquid"
C. I. Solvent Blue 63: 5.0 parts by mass Polyvinyl acetal resin: 5.0 parts by mass Toluene: 45.0 parts by mass Methyl ethyl ketone: 45.0 parts by mass

-Evaluation of print density Using a thermal transfer image receiving sheet and a test transfer recording medium, printing was performed with a thermal simulator, and the 255 gradation density was evaluated. All printing is done under the following conditions.
-Printing environment: 23 ° C 50% RH
・ Applied voltage: 24V
-Printing speed: 10 inches / sec
-Print density: main scan 300 dpi, secondary scan 300 dpi
・ Printing pressure: 10kgf
A print density of 1.30 or higher is considered acceptable.

-Evaluation of image quality of prints Using a thermal transfer image receiving sheet and a transfer recording medium for testing, printing was performed with a thermal simulator, and the image quality of the printed matter was visually evaluated. The printing is solid printing with 96 gradations, and all are performed under the following conditions.
-Printing environment: 23 ° C 50% RH
・ Applied voltage: 24V
-Printing speed: 10 inches / sec
-Print density: main scan 300 dpi, secondary scan 300 dpi
・ Printing pressure: 4kgf
Image quality Sensory evaluation Good: ◎, Average: ○, Bad: ×

The image receiving sheet for sublimation transfer of the present invention can be applied to a printer of the sublimation transfer method, and it is possible to obtain sufficient color development and good image quality.

1 ... Image receiving sheet for sublimation transfer 2 ... Base material 3 ... Resin layer 4 ... Insulation layer 5 ... Dye receiving layer

Claims (7)

An image receiving sheet in which resin layers are provided on both sides of a paper serving as a base material, and at least a heat insulating layer and a dye receiving layer are provided on one or both surfaces of the resin layer from the side close to the base material, and the side on which the heat insulating layer is provided. The thermal conductivity of the resin layer is 0.15 W / (mK) or less, and the maximum valley depth (JISB0601: 2013) Wv [unit: μm] of the waviness curve measured from the surface of the resin layer is 1.5 μm or less. An image receiving sheet for sublimation transfer, which is characterized by being. The image receiving sheet for sublimation transfer according to claim 1, wherein the heat insulating layer is made of a film containing voids. The image receiving sheet for sublimation transfer according to claim 2, wherein the film containing the voids contains at least polypropylene. The image receiving sheet for sublimation transfer according to claim 2 or 3, wherein the film containing the voids contains at least a polyester resin. The image receiving sheet for sublimation transfer according to claim 1, wherein the heat insulating layer is made of at least a pigment and a resin. The image receiving sheet for sublimation transfer according to claim 5, wherein the pigment is made of hollow particles. The image receiving sheet for sublimation transfer according to claim 5 or 6, wherein the hollow particles in the first half are formed by cross-linking an acrylic-styrene copolymer.

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