JP2588260B2 - Thermal transfer ink sheet and heat-resistant film used therefor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer ink sheet and a material thereof, and more particularly, to a thermal transfer ink sheet having improved heat resistance by a back coat material and a heat resistant ink used for the same. It is about a film.

[Problems to be solved by conventional technology and invention]

At present, thermal transfer type printers are widely used as small, lightweight and inexpensive popular printers. Examples of the heat-sensitive transfer medium include a heat transfer sheet provided with a heat sublimable dye on a support and a receiving sheet receiving a heat sublimable dye image by thermal printing from the back of the sheet, or a heat fusible substance and a pigment. A combination of a transfer sheet and a receiving sheet provided with a transfer layer of a dye or a dye on a support is also known. In addition, substances which react with each other and generate color by heat are supported on separate supports. There is also known a thermal transfer medium in which thermal printing is performed by contacting the thermal transfer media with each other.

As the application field of the thermal transfer type printer expands in this way, new requirements have never been created before.
The main ones are rough surface paper printing and high-speed printing. In response to these demands, printers have been widely improved together with inks. Particularly significant improvements include (1) changing the shape of the thermal head to a projection type, and (2) platen pressure (thermal head pressing pressure).
And (3) increasing the printing energy. As a result, while the printing conditions have become severer and the printing quality has made remarkable progress, a new important issue has arisen how to improve the heat resistance of the base film (mainly PET film) and the thermal transfer ink sheet.

To cope with such a problem, a silicone resin, an epoxy resin, a phenol resin, a fluororesin, a polyimide resin, a nitrocellulose resin, and the like as disclosed in JP-A-55-7467 have been used. These resins are insufficient in heat resistance and running properties.

In the case of using a liquid oil such as a silicone oil, a mineral oil, a vegetable oil, or a synthetic oil as disclosed in Japanese Patent Application Laid-Open No. 59-148797, the liquid oil is transferred to the ink side over time, resulting in a long period of time. At present, there is no satisfactory heat-resistant film for a thermal transfer ink sheet, for example, the runnability is extremely deteriorated after storage.

[Means for solving the problem]

The present inventors have conducted intensive studies in view of the above problems,
The present inventors have found that the running properties and heat resistance of a thermal transfer ink sheet can be improved by applying a combination of a specific resin and an oil to one surface of a film, thereby completing the present invention.

That is, the present invention relates to a thermal transfer ink sheet in which a thermal transfer ink layer is provided on a base film and a back coat material film is provided on the back surface of the base film, wherein the back coat material is a modified heat-resistant resin capable of forming an ionic bond or an ion pair. A thermal transfer ink sheet having increased thermal stability, characterized by containing a modified silicone oil, and a heat-resistant film for the thermal transfer ink sheet, wherein modified heat resistance can form ionic bonds or ion pairs on one surface of the film. An object of the present invention is to provide a heat-resistant film having increased thermal stability, characterized by being coated with a compound containing a resin and a modified silicone oil.

The modified heat-resistant resin capable of forming an ionic bond or an ion pair according to the present invention is a resin having a functional group capable of forming an ionic bond or an ion pair with a modified silicone oil,
Examples of the functional group include a carboxyl group, an amino group, a sulfonic group, and a phosphoric group. Specifically, the softening points of carboxyl-modified nitrocellulose resin, carboxyl-remaining polyester resin, carboxyl-remaining polyamide resin, amino-group-remaining polyamide resin, carboxyl-modified polyurethane resin, carboxyl-modified vinyl chloride-vinyl acetate copolymer, carboxyl-modified acrylic resin, etc. Is 10
Resins at 0 ° C. or higher are mentioned.

The modified silicone oil capable of forming an ionic bond or an ion pair according to the present invention is a silicone oil having a functional group capable of forming an ionic bond or an ion pair with the above-mentioned modified heat-resistant resin. Group, carboxyl group and the like. Specific examples include amino-modified silicone oil and carboxyl-modified silicone oil.

Preferred combinations of the back coat materials of the present invention include the combinations shown in Table 1.

As described above, the heat-resistance imparting agent (backcoat material) combining the modified heat-resistant resin and the modified silicone oil does not impair the lubricity of the silicone oil even after being applied to the film and suppresses migration of the silicone oil for a long time. It was also found to be stable to storage and excellent in running properties and heat resistance.

In the present invention, a carboxyl-modified nitrocellulose resin is particularly preferred as the modified heat-resistant resin, and an amino-modified silicone oil is particularly preferred as the modified silicone oil.

The carboxyl-modified nitrocellulose resin according to the present invention is, for example, a hydroxyl group (-OH) of purified natural cellulose.
The obtained by introducing a cellulose derivative obtained by replacing the nitrate group (-ONO ₂₎ (nitrocellulose resin) further oxidized to a carboxyl group (-COOH).

 An example of the structure of nitrocellulose is shown below.

Although the structure of the carboxyl-modified nitrocellulose is not clear, it is presumed that a carboxyl group is introduced at the terminal of the nitrocellulose.

Even when carboxyl-modified nitrocellulose is used alone as a back coat material for a thermal transfer ink sheet, the lubricity is insufficient.

The amino-modified silicone oil used in the present invention may be any silicone oil in which a compound having an amino group or an amino group in a molecule is introduced,
For example, there is a silicone oil in which a part of amino groups of a methyl group of dimethylpolysiloxane or an organic group having an amino group is introduced, and an example of the structure is shown below.

Wherein R represents a CH ₃ group or an OCH ₃ group, and n and m
Represents an integer of 1 or more. In addition, the amino-modified silicone oil according to the present invention utilizes a functional group of a modified silicone oil other than amino-modified such as alcohol-modified silicone oil, carboxyl-modified silicone oil, and epoxy-modified silicone oil. An amino group-containing silicone oil into which an amino group is introduced secondarily is also included. An example of a possible method for preparing an amino group-containing silicone oil is shown below.

(In the above formula, R represents an alkylene group or an arylene group.) In the present invention, the blending ratio of the modified heat-resistant resin and the modified silicone oil is preferably in the range of the following formula (1).

(Note) *: The functional group equivalent is an average molecular weight having 1 equivalent of a functional group. In the present invention, the blending ratio of the modified heat-resistant resin and the modified silicone oil preferably satisfies the formula (1), but generally, A blend in which 1 to 50 parts by weight of a modified silicone oil is added to 100 parts by weight of a modified heat-resistant resin can be used. If the amount of the modified silicone oil is less than 1 part by weight, the lubricating property which is the main function of the silicone oil cannot be sufficiently exhibited. On the other hand, when the amount exceeds 50 parts by weight, the coated surface after coating is not preferred because contamination of the solid ink surface increases.

Further, the coating amount of the back coat material in the present invention is 0.05
To 2.0 g / m ² (dry) it is suitable. If the amount is less than this range, the function of the composition as a back coat material becomes insufficient. If the amount is more than this range, heat conduction from the thermal head is hindered, and ink transfer failure may be caused.

The functional group equivalent of the modified heat-resistant resin used in the present invention is 2,000 to
The range of 20000 is preferable, and if it is less than 2000, it is not preferable because the heat resistance is insufficient or the coating strength is insufficient, and if it exceeds 2000, the addition amount of the modified silicone oil to be combined has to be reduced, so that it is required as a back coat material. It is not preferable because lubricity is insufficient.

The functional group equivalent of the modified silicone oil used in the present invention is
The range of 300 to 20,000 is preferable, and if it is less than 300, the added amount of the modified silicone oil is too small and the lubricity as a back coat material is insufficient, and if it exceeds 20,000, the coated surface of the back coat material becomes sticky and the ink surface It is not preferable because contamination increases.

In the present invention, other heat-resistant components (for example, silicone resin, epoxy resin, nitrocellulose resin, polyimide resin, polyvinyl chloride resin, etc.) or other lubricants may be added to the blend of the above-mentioned modified heat-resistant resin and modified silicone oil. It is possible to add an imparting component (for example, silicone oil, silica fine powder, alkyl phosphate, fluorine compound, etc.) according to the purpose. It is also possible to add a pigment such as carbon black to the back coat material in order to prevent static charge or leakage of confidential information.

As the film used in the present invention, a film having heat resistance, high dimensional stability and high surface smoothness is desirable, and specifically, polyethylene terephthalate (hereinafter, polyethylene terephthalate) which has been mainly used as a base film of a thermal transfer ink sheet. In addition to PET, a resin film made of polycarbonate, polyethylene, polystyrene, polypropylene, polyimide, or the like and having a thickness of 2 to 20 μm is suitably used.

The thermal transfer ink used in the present invention is not particularly limited,
Any of those used for ordinary thermal transfer ink sheets can be used.

〔Example〕

Hereinafter, the present invention will be described in more detail with reference to examples, and its advantages will be shown. However, the present invention is not limited to these examples.

In the examples, “parts” and “%” are based on weight unless otherwise specified.

Example 1 Amino-modified silicone oil (SF, manufactured by Toray Silicone Co., Ltd.) was applied to a carboxyl-modified nitrocellulose resin (Celnova BTK1 / 8, carboxyl equivalent 12500) manufactured by Asahi Kasei Corporation.
8417, amino equivalent 3500) in a weight ratio of 100: 20 (backcoat material) was used as a 10% by weight solution of toluene / cyclohexanone = 1/1 to form 0.3 g / m ² ( (At the time of drying) to obtain a heat-resistant film.

An actual running test was performed using a commercially available personal word processor (α-10, manufactured by Canon Inc.) using this heat-resistant film. That is,
An ordinary thermal transfer ink was applied to the opposite side of the surface of the heat-resistant film coated with the back coat material, and printing was performed while heating with a thermal head from the surface coated with the back coat material to evaluate heat resistance. As a result, it was found that even when the energy level of the thermal head was changed from the lowest level to the highest level by the print density adjusting dial, an extremely high-performance heat-resistant layer was formed without impairing the printing performance and running performance.

Example 2 Amino-modified silicone oil (SF 841 manufactured by Toray Silicone Co., Ltd.) was applied to a carboxyl-modified nitrocellulose resin (Celnova BTK SL, carboxyl equivalent 10,000) manufactured by Asahi Kasei Corporation.
A mixture obtained by mixing 7) at a weight ratio of 100: 30 is used as a 10% by weight toluene / cyclohexanone = 1/1 solution to prepare a 3.5 μM PET.
One side of the film was coated at a coating amount of 0.1 g / m ² (when dried) to obtain a heat-resistant film.

An actual running test was performed using a commercially available personal word processor (α-10, manufactured by Canon Inc.) using this heat-resistant film.
That is, a normal thermal transfer ink was applied to the opposite side of the heat-resistant film coated with the back coat material, and printing was performed while heating with a thermal head from the surface coated with the back coat material to evaluate heat resistance. As a result, it was found that even when the energy level of the thermal head was changed from the lowest level to the highest level by the print density adjusting dial, an extremely high-performance heat-resistant layer was formed without impairing the printing performance and running performance.

Example 3 A carboxyl-modified nitrocellulose resin (Celnova BTK SL) manufactured by Asahi Kasei Corporation was mixed with an amino-modified silicone oil (KF 861, amino equivalent: 2000) made by Shin-Etsu Silicone Co., Ltd.
The mixture blended at a weight ratio of 00:10 was made into a 10% by weight solution of toluene / methyl ethyl ketone = 1/1, and applied to one side of a 3.5 μm PET film at a coating amount of 1.2 g / m ² (when dried). A heat-resistant film was obtained.

An actual running test was performed using a commercially available personal word processor (α-10, manufactured by Canon Inc.) using this heat-resistant film.
That is, a normal thermal transfer ink was applied to the opposite side of the heat-resistant film coated with the back coat material, and printing was performed while heating with a thermal head from the surface coated with the back coat material to evaluate heat resistance. As a result, it was found that even when the energy level of the thermal head was changed from the lowest level to the highest level by the print density adjusting dial, an extremely high-performance heat-resistant layer was formed without impairing the printing performance and running performance.

COMPARATIVE EXAMPLE 1 The same amino-modified silicone oil as described in Example 1 alone was used as a 5% by weight cyclohexanone solution.
A heat-resistant film was obtained by applying a coating amount (at the time of drying) of 0.2 g / m ^{2 on} one surface of a PET film of μ. Although the coated surface was sticky, the same evaluation as in Example 1 was performed. At the same time, contamination of the thermal head with silicone oil was observed,
Due to stickiness of the silicone oil, conveyance failure occurred inside the thermal transfer cassette.

Comparative Example 2 A 10% by weight toluene coating of a back coat material containing the same carboxyl-modified nitrocellulose resin as described in Example 1 and an unmodified silicone oil (SH200) manufactured by Toray Silicone Co., Ltd. in a weight ratio of 100: 20. / Cyclohexanone = 1/1 solution, 0.2g / on one side of 3.5μ PET film
A heat-resistant film was obtained by coating with a coating amount of m ² (when dried).
When the same evaluation as in Example 1 was carried out, it was found that immediately after the application of the back coat material, an extremely high-performance heat-resistant layer was formed without impairing the running property and the printing performance. However, it was found that the silicone oil migrated to the ink surface during storage, which hindered the running performance.

Example 4 The ink sheets obtained in Examples 1 to 3 and Comparative Example 2 were subjected to a long-term storage stability test by the following method.

 Table 2 shows the results.

<Test Conditions> The ink sheets were pressed together at 50 ° C., 80% humidity and a pressure of 1 kg / cm ² so that the ink surface and the back coat application surface were overlapped, and allowed to stand for 30 days. Thereafter, the same evaluation as in Example 1 was performed.

As a result of the long-term storage stability test, all of the ink sheets of Examples 1, 2, and 3 showed good running properties and printing performance. However, in the ink sheet of Comparative Example 2, since the silicone oil migrated to the ink surface during long-term storage, the ink sheet had poor running properties and was fused to the thermal head.

Example 5 Amino-modified silicone oil (SF 841) manufactured by Toray Silicone Co., Ltd. was compared with a carboxyl residual polyester resin (Vylon 260, carboxyl equivalent 9350) manufactured by Toyobo Co., Ltd.
A mixture (backcoat material) obtained by mixing 7) in a weight ratio of 100: 10 was mixed with 10% by weight of toluene / methyl ethyl ketone = 8 /
Two solutions were applied to one side of a 3.5 μm PET film at 0.5 g / m ² (when dried) to obtain a heat-resistant film. When the same evaluation as in Example 1 was performed, it was found that an extremely high-performance heat-resistant layer was formed without impairing the running property and the printing performance.

Claims (8)

(57) [Claims] 1. A thermal transfer ink sheet having a thermal transfer ink layer provided on a base film and a back coat material film provided on the back surface of the base film, wherein the back coat material has a functional group capable of forming an ionic bond or an ion pair with each other. A thermal transfer ink sheet comprising a modified heat-resistant resin and a modified silicone oil. 2. A thermal transfer ink sheet having a thermal transfer ink layer provided on a base film and a back coat material film provided on the back surface of the base film, wherein the back coat material comprises a modified heat-resistant resin containing a carboxyl group in the molecule and a molecule. A thermal transfer characterized in that it contains a modified silicone oil containing an amino group in the molecule or a modified heat resistant resin containing an amino group in the molecule and a modified silicone oil containing a carboxyl group in the molecule. Ink sheet. 3. The thermal transfer ink sheet according to claim 2, wherein the modified heat-resistant resin is a carboxyl-modified nitrocellulose resin, and the modified silicone oil is an amino-modified silicone oil. 4. The back coat material is a composition in which 1 to 50 parts by weight of an amino-modified silicone oil is added to 100 parts by weight of a carboxyl-modified nitrocellulose resin.
The thermal transfer ink sheet as described in the above. 5. The thermal transfer ink sheet according to claim 3, wherein the carboxyl equivalent of the carboxyl-modified nitrocellulose resin is in the range of 2,000 to 20,000. 6. The thermal transfer ink sheet according to claim 3, wherein the amino equivalent of the amino-modified silicone oil is in the range of 300 to 20,000. 7. A thermal transfer ink obtained by applying on one surface of a film a compound containing a modified heat-resistant resin having a functional group capable of forming an ionic bond or an ion pair with a modified silicone oil. Heat resistant film for sheet. 8. A heat-resistant ink sheet for heat transfer, characterized in that one side of a film is coated with a composition obtained by adding 1 to 50 parts by weight of an amino-modified silicone oil to 100 parts by weight of a carboxyl-modified nitrocellulose resin. the film.