JPH0342282A - Thermal transfer sheet - Google Patents

Abstract

PURPOSE:To ensure that heat resistance, slipping and barrier properties are given to a rear layer simultaneously by forming a dye layer on the surface of a base film and a rear layer on the other surface, and forming the rear layer with a binder and the polyvalent metal salt of alkylphosphate. CONSTITUTION:A dye layer consisting of dye and binder resin is formed on the one surface of a base film, and a rear layer is formed with the binder and the polyvalent salt of alkylphosphate on the other surface. The dye layer should be 0.2 to 5.0 mum thick, preferably about 0.4 to 2.0mum. In addition, sublimable dye in the dye layer is equivalent to 5 to 90 wt% of the weight of the dye layer, ideally 10 to 70 wt%. The polyvalent metal salt of alkylphosphate is a compound expressed by formula (I) (in formula (I), R is a C12 or more alkyl group, M is an alkali earth metal, zinc or aluminum, n is the atomic valence of M). The preferable amount of use of the polyvalent metal salt is in the range of 10 to 200 pts.wt. for each 100 pts.wt. of binder.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a thermal transfer sheet using a sublimable dye (thermally transferable dye), and more specifically, it has excellent heat resistance, slip property and dye barrier, Therefore, it is an object of the present invention to provide a thermal transfer sheet with good storage stability.

(Prior art and its problems) Inkjet methods, thermal transfer methods, etc. have been developed as methods for providing excellent monochrome or full-color images simply and at high speed in place of conventional general printing methods. Among these, the so-called sublimation thermal transfer method using a sublimable dye is the most excellent as it has excellent continuous M gradation properties and provides a full-color image comparable to a color photograph.

The thermal transfer sheet used in the above-mentioned sublimation type thermal transfer method forms a dye layer containing a sublimable dye on one side of a base film such as a polyester film, and on the other side, it prevents the thermal head from sticking and improves slip properties. For this purpose, a back layer is generally used on the other side of the base film.

The dye layer surface of such a thermal transfer sheet is placed on an image receiving sheet having an image receiving layer made of polyester resin or the like, and by heating the thermal transfer sheet in an imagewise manner from the back side with a thermal head, the dye in the dye layer is transferred to the image receiving sheet. A desired image is formed.

Thermal transfer sheets as described above are generally manufactured using a continuous film as a base film, and are generally stored in a roll form from the time of manufacture until the time of use.

When the sheet is wound up into a roll and stored in this manner, a problem unique to sublimation thermal transfer sheets is that the dye layer and the back layer overlap, resulting in the dye in the dye layer transferring to the back layer. Therefore, the back layer is required to have 3 fl functions of dye barrier properties in addition to heat resistance and slip properties.

As a method of imparting dye barrier properties to the back layer, a method of forming a cured resin film that does not have dye stainability on the back layer has been proposed. However, when such a film is formed, the back layer may slip. This will result in a decline in sexuality. In order to improve this slip property, relatively low melting point silicone oil, wax, surfactant, etc. are added to the back layer, but because these additives have a low melting point,
On the other hand, there is a problem in that it migrates to the surface of the dye layer and impedes the transferability of the dye in the dye layer. Therefore, in the prior art, it has been extremely difficult to simultaneously impart heat resistance, slip properties, and barrier properties to the back layer.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a thermal transfer sheet having a back layer having excellent dye barrier properties as well as heat resistance and slip properties, and therefore also having excellent storage stability. It is.

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a thermal transfer sheet in which a dye layer consisting of a dye and a binder resin is formed on one side of the surface of a base film, and a back layer is formed on the other side, wherein the back layer is made of a binder and an alkyl resin. A thermal transfer sheet characterized in that it is formed from a polyvalent metal salt of a phosphoric acid ester.

(Function) By containing a polyvalent metal salt of alkyl phosphate ester as a lubricant in the back layer, a back layer having excellent dye barrier properties as well as heat resistance and slip properties is formed, and therefore thermal transfer with excellent preservability. A sheet is provided.

(Preferred Embodiments) Next, the present invention will be described in more detail by citing preferred embodiments.

The base film of the thermal transfer sheet of the present invention may be any conventionally known film having a certain degree of heat resistance and strength, for example, a thickness of about 0.5 to 50 μm, preferably about 3 to 10 μm. paper, various processed papers, polyester film, polystyrene film, polypropylene film, polysulfone film, aramid film, polycarbonate film, polyvinyl alcohol film, cellophane, etc., and particularly preferred is polyester film.

When the base film as described above has poor adhesion to the dye layer formed on its surface, it is preferable to subject the surface to an adhesion-facilitating treatment such as a brimer treatment or a corona discharge treatment.

The sublimable (thermally transferable) dye layer formed on the base film as described above is a layer in which a dye is supported by an arbitrary binder resin.

As the dye to be used, any dye used in conventionally known thermal transfer sheets can be effectively used in the present invention.
For example, some preferred dyes include red dyes, MS Red G, Macr
olex Red Violet R, Ceres R
ed7B, Samaron Red HBSL, R
Examples of yellow dye include e5olin Red F2O3, and examples of yellow dye include Holon Brilliant Yellow 6GL.
, PTY-52, Macrolex Yellow 6G, etc., and as the blue dye, Kayaset Blue 14
, Watasorin Blue AP-FW, Holon Brilliant Blue S-R, &IS Blue 100, and the like.

As the binder resin for supporting the heat-transferable dye as described above, any conventionally known binder resin can be used, and preferred examples include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, and acetic acid. Cellulose, cellulose resins such as cellulose acetate butyrate, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinylpyrrolidone,
Examples include vinyl resins such as polyacrylamide, polyesters, etc., and among these, cellulose-based, acetal-based, butyral-based, polyester-based, etc. are particularly preferred.

The dye layer of the thermal transfer sheet of the present invention is basically formed from the above-mentioned materials, but may also contain various conventionally known additives as required.

Preferably, such a dye layer is prepared by adding the above-mentioned sublimable dye, binder resin, and other optional components to a suitable solvent and dissolving or dispersing each component to prepare a paint or ink for forming the dye layer. It is formed by coating and drying on the above base film.

The dye layer formed in this way has a thickness of 0.2 to 5.0 am,
The thickness is preferably about 0.4 to 2.0 am, and the sublimable dye in the dye layer accounts for 5 to 90% of the weight of the dye layer.
Suitably it is present in an amount of 10% to 70% by weight.

The back layer, which mainly characterizes the present invention, is formed from a binder resin, a polyvalent metal salt of an alkyl phosphate ester, and other necessary additives.

As the binder resin, for example, ethyl cellulose,
Hydroxyethylcellulose, ethylhydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, cellulose acetate, lt[M cellulose, cellulose resins such as nitrified cotton, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acecool, polyvinylpyrrolidone, polyacrylamide, acrylonitrile - Vinyl resins such as styrene copolymers,
Examples include polyester resin, polyurethane resin, silicone-modified or fluorine-modified urethane. Among these, it is preferable to use those having some reactive groups, for example, hydroxyl groups, and to use polyisocyanate or the like as a crosslinking agent in combination to form a crosslinked resin layer.

Furthermore, as the binder resin, an acrylonitrile/styrene copolymer is particularly preferred since it can form a back layer with excellent heat resistance without crosslinking.

The above styrene/acrylonitrile copolymer.

It is obtained by copolymerizing styrene and acrylonitrile, such as Sevian AD, Sevian LD,
Products of various grades are easily available on the market under names such as Cevian NA (manufactured by Daicel Chemical Company), and any of them can be used in the present invention, and can be easily produced according to conventional methods.

Particularly suitable styrene/acrylonitrile copolymers have a molecular weight of 10,000 to 200,000, preferably 150,000 to 190,000, and an acrylonitrile content of 20,000 to 200,000, among various grades.
The content is 0 to 40 mol%, preferably 25 to 30 mol%, and those with a softening temperature of 400° C. or higher as determined by differential thermal analysis are preferred from the viewpoint of dissolution stability in organic solvents and heat resistance.

When a polyethylene terephthalate film is selected as the base film, the above styrene/acrylonitrile copolymer does not have sufficient adhesion to the base film, so when producing the styrene/acrylonitrile copolymer, a small amount, e.g. It is preferable to copolymerize a monomer (for example, meth (acrylic acid, etc.)) having several mol % of a functional group.

Alternatively, a method can be used in which a small amount of other adhesive resin is used in combination, or a method in which a primer layer is previously formed on the base film using these adhesive resins.

Preferred adhesive resins are amorphous linear saturated polyester resins with a glass transition point of 50°C or higher, such as products such as Vylon (manufactured by Toyobo), Elitere (manufactured by Unitika), and Polyester (manufactured by Nippon Gosei Kagaku). Various grades are available on the market, and any of them can be used in the present invention.

A particularly preferred example is Vylon RV290 (manufactured by Toyobo, epoxy group-introduced product, molecular weight 20,000 to 25,000, 7 g 77°C, softening point 180°C, hydroxyl value 5 to 8).

When forming a primer layer using the above polyester resin, it is preferable to form a layer with a thickness of about 0.05 to 0.5 μm. If it is too thin, the adhesiveness will be insufficient, while if it is too thick, the sensitivity of the thermal head will increase. This is not preferable because it may cause a decrease in heat resistance.

When mixed with the styrene/acrylonitrile copolymer, it is preferably used at a ratio of 1 to 30 parts by weight per 100 parts by weight of the styrene/acrylonitrile copolymer. If the amount used is too small, adhesion may occur. On the other hand, if the amount is too high, the heat resistance of the back layer will decrease and sticking property will occur, which is not preferable.

The polyvalent metal salt of an alkyl phosphate used in the present invention and which mainly characterizes the present invention is obtained by replacing the alkali metal salt of an alkyl phosphate with a polyvalent metal, and is itself an additive for plastics. It is known as an agent, and various grades are available on the market, and any of them can be used in the present invention.

A particularly preferred polyvalent metal salt of an alkyl phosphate ester in the present invention is represented by a structural formula, in which R is an alkyl group having 12 or more carbon atoms such as a cetyl group, a lauryl group, or a stearyl group, particularly a stearyl group, and M is an alkaline earth metal such as barium, calcium, magnesium, zinc or aluminum. Note that n represents the valence of M.

The amount of the polyvalent metal salt of the alkyl phosphate ester used above is:
The range is preferably 10 to 100 parts by weight per 100 parts by weight of the binder, and if the amount used is less than the above range,
On the other hand, if it exceeds the above range, the physical strength of the back layer will decrease, which is not preferable.

In addition, in the present invention, when forming the back layer from the above-mentioned materials, thermal mold release agents such as wax, higher fatty acid amide, ester, surfactant, higher fatty acid metal soap, etc. or a lubricant.

In addition, in order to improve the heat resistance of the back layer, as a heat resistant agent,
Hydrotalcite DHT-4A (manufactured by Kyowa Chemical Industry)
, Talc Micro Ace L-1 (manufactured by Nippon Talc), Teflon LeBron L-2 (manufactured by Daikin Industries), Graphite Fluoride 5CP-1o (manufactured by Sanpo Chemical Industries), Graphite AT40S
(manufactured by Oriental Sangyo) or include fine particles of silica, calcium carbonate, precipitated barium, urea resin crosslinked powder, styrene/acrylic resin crosslinked powder, amino resin crosslinked powder, silicone powder, wood powder, molybdenum disulfide, boron nitride, etc. I can do it.

Further, a conductive agent such as carbon black can also be added for the purpose of imparting antistatic properties to the back layer.

To form the back layer, prepare a coating solution by dissolving or dispersing the above materials in a suitable solvent such as acetone, methyl ethyl ketone, toluene, xylene, etc., and apply this coating solution to a gravure coater, roll coater, etc. It is formed by coating with a conventional coating means such as , wire bar, etc. and drying.

The coating amount, that is, the thickness of the back layer is also important, and in the present invention, the solid content is 0.5 g/d or less, preferably 0.1 g/d or less.
A back layer having sufficient performance can be formed with a thickness of 0.5 g/rn' to 0.5 g/rn'.

If the back layer is too thick, the sensitivity during transfer will decrease, which is not preferable.

The image-receiving sheet used to form an image using the thermal transfer sheet as described above may be of any type as long as its recording surface has dye-receptive properties for the above-mentioned dyes. In the case of paper, metal, glass, synthetic resin film or sheet, etc., which do not have a dye, a dye-receiving layer may be formed on at least one surface thereof using a resin having good dye-dyeability. In addition, in such a dye-receiving layer, solid waxes such as polyethylene wax, amide wax, and Teflon powder, which are known as release agents, fluorine-based or phosphate-based surfactants, silicone oil, etc. are used for the purpose of the present invention. It can be contained within a range that does not interfere with.

As the means for applying thermal energy during thermal transfer using the thermal transfer sheet of the present invention, any conventionally known applying means can be used, such as a recording device such as a thermal printer (for example, Video Printer VY-100 manufactured by Hitachi, Ltd.) By controlling the recording time, the intended purpose can be fully achieved by applying thermal energy of about 5 to 100 mJ/mm'.

(Effects) According to the present invention as described above, although the polyvalent metal salt of alkyl phosphate used in the present invention has extremely excellent slip properties, it does not exceed 150°C in many cases. 2
Since it has a melting point of 00℃ or higher, it has excellent heat resistance, does not contaminate other articles or the thermal head, and does not wear out the thermal head, and has even better dye barrier properties. A thermal transfer sheet is provided.

(Example) Hereinafter, the present invention will be explained in more detail by giving Examples and Comparative Examples. In the text, parts or percentages are based on weight unless otherwise specified.

Examples 1 to 5 Voice Ink Material l Polyvinyl butyral resin (S-LEC 0X-1゜ manufactured by Fountain Chemical Co., Ltd.) 6.0 parts Zinc stearyl phosphate (LBT 1830, manufactured by Sakai Kagaku ■)
6.0 parts Urea resin powder (organic filler, manufactured by Nippon Kasei ■) 1.8 parts Solvent HMε/toluene = 1/11
86. 2 parts Ink 2 Polyvinyl butyral resin (S-LEC BX-1° manufactured by Fountain Chemical Co., Ltd.) 4.0 parts Polyvinyl butyral resin (S-LEC BLS).

2.0 parts Aluminum stearyl phosphate (LOT1813, manufactured by Sakai Kagaku ■) 6.0 parts Melamine resin powder (Eposter S, manufactured by Nippon Shokubai Chemical ■)
1.8 parts acrylic resin crosslinking (GL-1o
o, manufactured by Soken Kagaku ■) 2,0 parts Yoshii II (MEK/) Luene = l/l)
84. After stirring and mixing 2 parts of the above composition and dispersion treatment for 3 hours with a paint shaker, treated product 10
0 parts to 16 parts of polyisocyanate curing agent (Coronate, manufactured by Nippon Polyurethane Kiki) and diluting solvent fMEK/
An appropriate amount of toluene (l/1) was added to prepare ink for each back layer.

Each of the above inks was applied to a polyester film (thickness 6 μm).
Solid content 0.2g/d and 0.5g/r on one side of m1 Lumirror F-53 (manufactured by Toshi ■) using a wire bar coater.
After coating at a ratio of n'', heat treatment was performed in an oven at 60° C. for 48 hours to form a back layer.

1 Ink 3 Styrene/acrylonitrile copolymer (Sevian AD,
Daicel Chemical ■) 6.0 parts Cotton-like saturated polyester resin (Eliteir UE3200, Unitika ■) 0.3 parts Zinc stearyl phosphate 1- (LBT 1830, Sakai Chemical ■)
3.0 parts urea resin powder (organic filler,
Nippon Kasei (manufactured by Tsuyoshi) 3.0 parts melamine resin powder (Eposter S, manufactured by Nippon Shokubai Kagaku ■)
l, 5 parts elution II fM
EK/) Luen = 1/11
86. 2 parts Ink Material 4 Nitrified cotton H1/2 second resin (Seltsuba BTHI/2, manufactured by Mukaseikyo) 10.0 parts Linear saturated polyester resin (Eritaire UE3200, manufactured by Unitika ■) 2.0 parts Zinc stearyl phosphate (LBT 1830. Manufactured by Sakai Chemical)
5.0 parts Urea resin cross-linked powder (organic filler, manufactured by Nippon Kasei ■) 3.0 parts Melting method fMEK/) Lumira = 1/11
80. 0 parts Ink 5 Cellulose acetate propionate resin (CAP 4
82-05, made by Eastman Kodak) 10.0 parts cotton-like saturated polyester resin (Elytail UE3200,
2.0 parts zinc stearyl phosphate (LBT 1830, manufactured by Sakai Kagaku ■)
3.0 parts Lithium stearate (S-7000, manufactured by Sakai Chemical ■) 5.0 parts Solvent J (MEK/) Lumira 1/11
80. 0 parts After stirring and mixing the above composition,
Dispersion treatment for 3 hours with a paint shaker and dilution solvent fME
An appropriate amount of Lumira/l/1) was added to prepare ink for each back layer.

Each of the above inks was applied to a polyester film (thickness 6 μm).
Solid content 0.2g/M and 0.5g/m with a wire bar coater on one side of Lumirror F-53, manufactured by Toshi ■
After coating at a ratio of 100%, the film was dried with hot air to form a back layer.

Next, an ink composition for forming a dye layer having the following composition was prepared, and applied to the other side of the base film on which the back layer was formed using a wire bar so that the dry coating amount was 2.0 g/m' and dried. A thermal transfer sheet of the present invention was obtained.

Disperse dye (Kayaset Blue 14, Nipponka Yakuri) 4,
0 parts Polyvinyl butyral resin (S-LEC BX-1, manufactured by Mikki Kagaku) 4.3 parts Methyl ethyl ketone/toluene (weight ratio 171180.0 parts Isobutanol 10.0 parts Synthetic paper' (Yupo FRG-150, thickness 150 μm 1 Oji) A coating solution with the following composition was applied using a bar coater at a drying rate of 4.0 g/d on one side of the paper (Yuka Co., Ltd.) and dried to form a dye-receiving layer, and a thermal transfer image-receiving sheet was formed. Obtained.

Standing limb targeting polyester (Byron 103, manufactured by Toyobo Co., Ltd.) 8,0 parts Polymer plasticizer (Elvaloy 741P, manufactured by Mitsui Polychemicals ■) 2,0 parts Amino-modified silicone oil (KF-393, manufactured by Shin-Etsu Silicone Co., Ltd.)
0.125 parts epoxy modified silicone oil (X-22-343, manufactured by Shin-Etsu Silicone Kiki)
0.125 parts toluene 7
0.0 part Methyl ethyl ketone 10.0 parts Cyclohexanone 20.0 parts Using the thermal transfer sheet of the present invention obtained above, the output IW/dot was 0.3 to 4.5 m5e during pulse with a thermal printer.
When printing was performed on the above image receiving sheet at a dot density of 3 dots/mm, no sticking phenomenon occurred, no wrinkles occurred, and the thermal transfer sheet ran smoothly without any problems.

Furthermore, wrap the thermal transfer sheet around the paper tube. When the dye layer and the back layer were in close contact with each other, an accelerated aging test was conducted for 14 days in an oven at 50°C, and it was found that the back layer was contaminated due to migration of the dye in the dye layer, and the back layer was contaminated due to migration of the dye in the dye layer. No contamination of the dye layer due to migration was observed.

Comparative Example 1 A thermal transfer sheet of a comparative example was obtained in the same manner as in Example 1 except that zinc stearyl phosphene was not used.

When a printing test was conducted in the same manner as in Example 1, the sticking phenomenon was severe and printing was impossible.

Further, as a result of a similar accelerated test, migration of the dye layer was severe and the back layer was strongly colored.

Furthermore, when the thermal transfer sheets of Examples and Comparative Examples were measured for staking resistance and stain resistance, the results shown in Table 1 below were obtained.

Sticking resistance: fil test machine thin film head 6d/mm 17V2
ms=1.66mJ/d solid printing (2) Practical i Thin film head 6d/mm 12V8
ms = 1.66 mJ/d Printing storage stability: The dye layer surface and back layer surface of a test piece (50 x 50 mm) were overlapped and a constant load was applied using a blocking tester to compare performance under the following conditions.

(1) 55℃/5Kg/crn”/48 hours (2) 60℃/2Kg/cm”/24 hours

Claims (2)

[Claims] (1) In a thermal transfer sheet in which a dye layer consisting of a dye and a binder resin is formed on the surface of a base film, and a back layer is formed on the other surface, the back layer is a binder and a polyvalent metal salt of an alkyl phosphate ester. A thermal transfer sheet characterized by being formed from. (2) The polyvalent metal salt of alkyl phosphate ester has the formula ▲,
There are chemical formulas, tables, etc. ▼ and/or ▲ mathematical formulas, chemical formulas,
There are tables etc. ▼ Claim 1 which is a compound represented by (R is an alkyl group having 12 or more carbon atoms, M is an alkaline earth metal, zinc or aluminum, and n represents the valence of M) Thermal transfer sheet described. (3) The thermal transfer sheet according to claim 1, wherein the polyvalent metal salt of the alkyl phosphate ester is present in an amount of 10 to 200 parts by weight per 100 parts by weight of the binder.