JP3368383B2 - Thermal transfer recording medium - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording medium used in printers such as computers and word processors, bar code printers and the like.

[0002]

2. Description of the Related Art In recent years, a thermal transfer recording method using a thermal head is advantageous in that it is noiseless, that the apparatus is relatively inexpensive and can be downsized, that maintenance is easy, and that printed images are stable. It has been used a lot since. Typical examples of the thermal transfer recording medium used in such a thermal transfer recording system are: (1) A heat-meltable ink layer comprising a colorant and a binder is directly provided on a support. (2) One in which a heat-meltable ink layer composed of a colorant and a binder is provided on a support through a release layer containing wax as a main component, and the like. (1) and (2)
In this type, a conventionally known wax is used as a main component, and an oil-based ink layer or release layer is applied in a state of being melted or dispersed in a hot melt or an aqueous or non-aqueous solvent, and water contained in a coating liquid is used. Alternatively, it is formed by completely removing the organic solvent by drying.

In recent years, various resins and waxes can be used, and the ratio thereof can be changed greatly, so that various functions such as heat resistance, scratch resistance and solvent resistance can be exerted, and thin film coating is possible. The so-called solvent coating type, in which the latter is applied in a state of being dissolved or dispersed in an aqueous or non-aqueous solvent and then dried, is increasing because the particulate coating can be freely performed. In the case of an aqueous solvent, it is even more safe, and
When the coating layer is laminated, there is an advantage that the lower layer is not dissolved.

However, in the case of an aqueous system, the surface tension is large (72.8 dyn / cm), and in the case of an ink solution or a stripping solution, the solution is repelled when applied on a substrate such as a polyester film or a stripping layer mainly composed of wax. However, there was a drawback that a uniform thin film coating could not be performed.

[0005]

An object of the present invention is to form a uniform thin film without causing cissing even when applied on a polyester film substrate or a wax-based release layer.
The object is to obtain a thermal transfer recording medium which is excellent in heat sensitivity and resolution as well as in abrasion resistance of an image.

[0006]

According to the present invention , the following is provided.
An invention is provided . In a thermal transfer recording medium formed by laminating a release layer on a support and further a heat-meltable ink layer thereon, the heat-meltable ink layer comprises a colorant, waxes and
And / or a heat-meltable component consisting of resins only as the main component
The heat-meltable ink layer is formed by an aqueous coating liquid containing an alcohol-based surfactant having an acetylene group in an amount of 0.01 to 20% by weight based on the solid content of the coating liquid component. Thermal transfer recording medium.

It has already been proposed that the heat-meltable ink layer contains a polyhydric alcohol having an acetylene group to improve heat resistance and the like (JP-A-3-2445).
No. 90). However, with these methods,
Since the polyhydric alcohol is used in a relatively large amount due to the difference in the purpose of use (30% or more, preferably 50 to 150% with respect to the solid content of the coating liquid), it has a cissing prevention effect,
Aggregates are likely to appear, which tends to cause unevenness. In this respect, even if the addition amount is large, it is 20% with respect to the solid content of the aqueous coating solution.
%, And if it is in the range of at least 0.01%, there is also a cissing-preventing effect, and uniform coating can be carried out without producing aggregates.

In addition, those containing a fluorine-based or silicon-based surfactant (see JP-A-3-2092) and those containing a polyhydric alcohol (JP-A-5-205).
No. 8-129074) is known, but in the former case, the surface tension is too low and bubbles tend to form, and it is difficult to obtain a uniform coating film surface. In the latter case,
The surface tension is not lowered, which is not suitable for the purpose of the present invention.

In the present invention, the acetylene group-containing alcoholic surfactant preferably used is a compound represented by the following general formula (I), (II) or (III).

[0010]

[Chemical 5] (In the formula, R _{1 and} R ₂ represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and 1 = 0 to 30)

[0011]

[Chemical 6] (In the formula, R _{1 to} R ₄ represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and m + n = 0 to 30)

[Chemical 7] (In the formula, R _{1 to} R ₄ represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and m + n = 1 to 30)

[0012]

[Table 1]

These compounds have surface tensions of 31 to 31.
With 50 dyn / cm, a good coating liquid can be prepared with excellent wettability and less liquid bubbles. Further, even if it is applied on a carnauba wax or a PET film (support) with an aqueous coating liquid, there is no cissing, and even if the coating liquid is applied on it, no cissing occurs and it can be applied neatly.

As described above, the amount added is 0.01 to 20%, preferably 0.03 to 10%, based on the solid content of the coating liquid. If the amount is too small, the cissing prevention effect is not exhibited, and if the amount is too large, the heat resistance and abrasion resistance of the ink are deteriorated. If l and m + n of the compound of the above general formula are too large, bubbles are large, and the heat resistance and abrasion resistance of the ink are deteriorated.

On the other hand, when a thermal transfer ink layer containing an organic solvent is coated with an organic solvent, the repellency does not occur and the coatability is good, but the particle size becomes large and the ink layer easily slips and scumming easily occurs. Become.

Typical examples of the layer structure of the present invention are shown in FIGS. 2 to 3, but are not limited to these. At least the heat-meltable ink layer 3 of the layer constitution in which the release layer 4 is further formed on the support 1 and the heat-melted ink layer 3 is further formed thereon, contains an acetylene group-containing alcoholic surfactant.
Further, it may be added to the release layer 4 and the over layer 5, and it is particularly preferable to add it when the release layer 4 and the over layer 5 are coated with an aqueous system. It should be noted that FIG. 1 does not include the release layer 4, and shows the layer structure of Reference Example 1.

As the support, for example, polyester,
In addition to relatively heat-resistant plastic films such as polycarbonate, triacetyl cellulose, nylon, and polyimide, there are glassine paper, condenser paper, metal foil, etc., the thickness of which is about 2 to 15 μm, preferably 3 to 10 μm.
It is in the range of μm.

The surface of the support which is in contact with the thermal head (the surface opposite to the side where the ink layer 3 is present) is, if necessary, silicone rubber, silicone resin,
The heat resistance of the support can be improved by providing the heat resistant protective layer 2 made of fluororesin, polyimide resin, epoxy resin, phenol resin, melamine resin, nitrocellulose, cellulose acetate propionate or the like, or Support materials which could not be used can also be used.

The peeling layer 4 is composed of at least one of waxes, resins and unvulcanized rubber.

Examples of the waxes include natural waxes such as carnauba wax, candelilla wax, beeswax, wood wax, montan wax and whale wax; paraffin wax, microcrystalline wax, oxidized wax,
Synthetic waxes such as polyethylene wax; other higher fatty acids such as margaric acid, lauric acid, mistyric acid, palmitic acid, stearic acid, flomenic acid and behenic acid and their metal salts; higher alcohols such as stearyl alcohol and behenyl alcohol; sorbitan Esters such as fatty acid esters; and amides such as stalinamide and oleinamide.

As the resins, polyamide type, polyester type, polyurethane type, vinyl chloride type, vinyl chloride vinyl acetate type,
In addition to cellulose-based, rosin-based, petroleum-based, styrene-based, butyral-based, terpene-based, and phenol-based resins, ethylene-vinyl acetate copolymers and ethylene-acrylic resins are listed.

Examples of the unvulcanized rubber include polyisoprene, polybutadiene, styrene butadiene rubber, nitrile rubber, ethylene propylene rubber, butyl rubber, silicon rubber, fluorine rubber and urethane rubber. Particularly preferred are polyisoprene, polybutadiene, ethylene propylene rubber, butyl rubber and nitrile rubber.

The peeling layer 4 is formed by applying and drying in a state of being dissolved or dispersed in hot melt or a solvent or in a state of being dispersed in water. The amount of the adhering substance is 0.3 to 5 g / m ² , preferably 0.5 to 3 g / m ² .

The heat-meltable ink layer 3 is composed of at least one layer and is composed of a conventionally known heat-meltable layer. Specifically, it mainly contains a colorant, waxes and resins.

The colorant is appropriately selected from conventionally known dyes and pigments.

Examples of waxes include paraffin wax, microcrystalline wax, oxidized paraffin wax, candelilla wax, carnauba wax, montan wax, ceresin wax, polyethylene wax, oxidized polyethylene wax, castor wax beef tallow oil, lanolin, wood. Wax substances such as wax, sorbitan stearate, sorbitan palmitate, stearyl alcohol, polyamide wax, oleylamide, stearylamide, hidoxystearic acid, synthetic ester wax, etc. may be mentioned.

As the resins, polyamide type, polyester type, polyurethane type, vinyl chloride type, vinyl chloride vinyl acetate type,
In addition to cellulose-based, rosin-based, petroleum-based, styrene-based, butyral-based, and phenol-based resins, ethylene-vinyl acetate copolymers and ethylene-acrylic resins can be mentioned. The coating amount (adhesion amount) of the heat-meltable ink layer is 1 to
It is 10 g / m ² , preferably 1 to 3 g / m ² .

The over layer can also be provided by a material and coating method similar to that of the release layer. The layer may contain a coloring agent to the extent that it does not cause scumming. The adhesion amount is 0.1 to 3 g / m ² , preferably 0.3 to ² g / m ² .

[0029]

The present invention will be further described with reference to the following examples. All are expressed in parts by weight.

Reference Example 1 Polyethylene terephthalate (PE having a thickness of 4.5 μm)
T) After the liquid of the following component A is dried on the film, the adhesion amount is 2.
Apply with a wire bar so that the amount becomes 5g / m2, and apply at 60 ℃ for 2
It was dried for a minute to form a heat-meltable ink layer. (Component A) Carnauba wax water dispersion (average particle size 1.5 μm, solid content 30%) 56 parts Carbon black water dispersion (solid content 20%) 16 parts Water 14 parts Methanol 13.5 parts Table 1 Compound of (3) 0.1 part (0.5% relative to the solid content of component A) Further, a 1% toluene solution of silicone rubber was dried on the ink layer and the surface on the reflection side by a wire bar, and the adhesion amount was 0.05 g /
m2 was applied and dried at 50 ° C for 2 minutes to obtain a thermal transfer recording medium.

Example 1 The following component B was dispersed on one side of a (PET) film having a thickness of 4.5 μm by a ball mill for 10 hours to give an average particle size of 3.0 μm.
After the coating solution for release layer was dried, it was applied with a wire bar so as to have an adhesion amount of 1.5 g / m ² , and dried at 40 ° C. for 2 minutes. (Component B) Powdered carnauba wax (100 mesh all-through) 9 parts Ethylene vinyl acetate copolymer 1 part Toluene 60 parts MEK 30 parts Next, a heat-meltable ink layer coating solution of the following component C is dried on this release layer. After that, it was applied with a wire bar so that the adhesion amount was 2.0 g / m ² , and dried at 60 ° C. for 2 minutes. (Component C) Carnauba wax water dispersion (average particle size 0.4 μm, solid content 30%) 40 parts Carbon black water dispersion (solid content 20%) 15 parts Hydrogenated rosin water dispersion (solid content 30 %) 10 parts Water 34 parts Compound of (7) in Table 1 0.5 parts (2.8% based on solid content of C component) 1% toluene of silicone rubber on the surface opposite to the ink layer of the PET film The solution was dried with a wire bar, then applied so that the amount of adhesion was 0.05 g / m ² , and dried at 50 ° C. for 2 minutes to provide a heat resistant protective layer to obtain a thermal transfer recording medium.

Example 2 On the ink layer of Example 1, an overlayer coating liquid of the following component D was further dried and then applied with a wire bar so that the amount of adhesion would be 1.0 g / m ² , and the temperature was 60 ° C. And dried for 2 minutes. (Component D) Carnauba wax aqueous dispersion (average particle size 0.4 μm, solid content 30%) 40 parts Water 40 parts Compound (8) in Table 1 (m = 2, n = 2) 0.3 parts (2.5% based on the solid content of component D)

Example 3 In Example 1, the compound of (8) (m = 5, n = 5) was used in place of the compound (7) (2.8% based on the component C solid content). A thermal transfer recording medium was prepared in the same manner as in Example 1 except for the above.

Comparative Example 1 A thermal transfer recording medium was prepared in the same manner as in Example 1 except that the compound (7) was not added in Example 1.

Comparative Example 2 A thermal transfer recording medium was prepared in the same manner as in Example 2, except that a silicon-based surfactant was used instead of the compound (8) in the coating liquid .

Comparative Example 3 In Reference Example 1, the amount of the compound (7) added was 5 parts (C
A thermal transfer recording medium was prepared in the same manner as in Reference Example 1 except that the solid content of the components was 28%).

The thermal transfer recording media of Reference Example 1, Examples 1 to 3 and Comparative Examples 1 to 3 were printed on cast coated paper using a thermal transfer simulator. Printing conditions are printing speed 100 mm / sec, printing energy 20 mj /
mm ² (thin film glaze thermal head, 8 dots /
mm). The results are shown in Table 2.

[0038]

[Table 2]

[0039]   Print density: Measured with a Macbeth reflection densitometer. Resolution: Excellent ... 1 dot line for every 1 dot is independent.         Good …… One dot line for each dot is connected here and there. Image rub resistance: Excellent ... Even if the cardboard is rubbed 100 times at 50 ° C, there is no effect.               Good …… Spot image when rubbing cardboard 100 times at 50 ℃                     It is disturbed but legible.               Defective ... When rubbing cardboard 100 times at 50 ° C, the image is distorted                     Unreadable

It is apparent from Table 2 that the coatings obtained in Examples are clean without cissing and have good image rub resistance as well as image density and resolution.

[0041]

As described above, the heat-meltable ink layer is formed by the water-based coating liquid containing a small amount of the alcohol-based surfactant having an acetylene group, so that a uniform thin film without cissing during the coating film formation can be obtained. It is possible to obtain a thermal transfer recording medium having excellent image abrasion resistance and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a layer structure of Reference Example 1.

FIG. 2 is a sectional view showing a layer structure of the present invention.

FIG. 3 is a sectional view showing a layer structure of the present invention.

[Explanation of symbols]

1 support 2 Heat-resistant protective layer 3 Heat-meltable ink layer 4 Release layer 5 over layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor, Tadafumi Tadafumi               1-3-3 Nakamagome, Ota-ku, Tokyo Stock               Inside the ceremony company Ricoh (72) Inventor Shinji Okada               1-3-3 Nakamagome, Ota-ku, Tokyo Stock               Inside the ceremony company Ricoh                (56) References JP-A-61-255896 (JP, A)                 JP-A-3-293189 (JP, A)                 JP 58-89392 (JP, A)                 JP-A-3-43291 (JP, A)

Claims (3)

(57) [Claims] 1. A thermal transfer recording medium comprising a support, a release layer, and a heat-meltable ink layer laminated thereon, wherein the heat-meltable ink layer comprises a colorant, waxes, and / or wax.
Alternatively, the main component is a heat-meltable component consisting only of resins
It is characterized in that the heat-meltable ink layer is formed by an aqueous coating liquid containing an alcohol-based surfactant having an acetylene group in an amount of 0.01 to 20% by weight based on the solid content of the coating liquid component. Thermal transfer recording medium. 2. The thermal transfer recording medium according to claim 1, wherein the alcohol-based surfactant having an acetylene group is a compound represented by the following general formula (I) or (II). [Chemical 1] (In the formula, R _{1 and} R ₂ represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and 1 = 0 to 30) (In the formula, R ₁ to R ₄ represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and m + n = 0 to 30) 3. A thermal transfer recording medium comprising a support, a release layer, and a heat-meltable ink layer laminated on the release layer, wherein the heat-meltable ink layer comprises a colorant, waxes, and / or wax.
Alternatively, the main component is a heat-meltable component consisting only of resins
The thermal transfer recording medium is characterized in that the heat-meltable ink layer is formed from an aqueous coating liquid containing a compound represented by the following general formula (I) or general formula (III). [Chemical 3] (In the formula, R _{1 and} R ₂ represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and 1 = 0 to 30). (In the formula, R _{1 to} R ₄ represent hydrogen or an alkyl group having 1 to 6 carbon atoms, and m + n = 1 to 30)