JP2941965B2 - 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.

[0002]

2. Description of the Related Art As a thermal transfer recording medium used for thermal transfer recording, a heat-fusible colored ink (hereinafter, referred to as a pigment) obtained by dispersing a color pigment (hereinafter, referred to as a pigment) in a wax, a heat-fusible resin or the like on a heat-resistant support. , Ink) has been conventionally used.

[0003] Efforts have been made to reduce the amount of the ink applied from the viewpoint of improving the resolution and abrasion resistance of a printed image obtained by thermal transfer, and from the viewpoint of improving the transfer sensitivity for high-speed printing.

However, conventional inks have poor fluidity at the time of melting, so that it is difficult to apply them by hot-melt coating. In particular, it is difficult to obtain a uniform coating film with a low coating amount, and when the amount of pigment in the ink is increased, Since the fluidity is further deteriorated, a sufficient amount of the pigment cannot be added. As a result, there have been disadvantages such as insufficient density of the image obtained by thermal transfer. In particular, pigments having a small particle size, high coloring power, and good resolution have a strong tendency to cause such a problem, so that there is a problem that types of usable pigments are limited.

[0005]

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned drawbacks of the conventional thermal transfer recording medium and achieves a practical image density even at a low coating amount by forming a uniform low-coating amount ink layer having a high pigment concentration. It is an object of the present invention to provide a thermal transfer recording medium in which the resolution of printed images and the abrasion resistance are improved, and the high-speed printing compatibility is further improved.

[0006]

According to the present invention, there is provided a heat transfer recording medium comprising a heat-meltable colored ink containing a color pigment on a heat-resistant support, which is coated with a heat-meltable ink. The present invention relates to a thermal transfer recording medium using a pigment obtained by dispersing a pigment in a heat-fusible medium using a metal phthalocyanine compound as a dispersant.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dispersing one or more kinds of pigments such as copper phthalocyanine pigments and carbon black in a heat-fusible medium by using a metal phthalocyanine compound,
For example, the present invention has been completed by finding a new fact that, when iron phthalocyanine or tin phthalocyanine is used as a dispersant, the fluidity and dispersibility of the ink at the time of melting are improved.

As described above, since the melt fluidity of the ink is improved, a uniform ink layer can be formed even with a small amount of coating. As a result, a thin ink layer having a high pigment concentration can be obtained, so that the resolution and scratch resistance of the printed image can be improved while securing a practical printed image density. Further, since the ink layer is thin and the transfer sensitivity is improved, it is possible to cope with high-speed printing.

The pigment used in the present invention is not particularly limited as long as it is well dispersed using the above-mentioned metal phthalocyanine compound as a dispersant, and preferable examples thereof include copper phthalocyanine pigment and carbon black. Copper phthalocyanine pigments include copper phthalocyanine blue,
Alternatively, those having a structure in which 1 to 16 chlorine atoms or the like are substituted on the phthalocyanine ring, such as copper phthalocyanine green, may be mentioned.

The particle size of the pigment is desirably small from the viewpoint of coloring power and resolution. For example, the average particle size of primary particles is preferably about 0.02 to 0.06 μm. In the present invention, even if such a pigment having such a small particle diameter is used, an ink having good fluidity at the time of melting can be obtained.

In the present invention, a metal phthalocyanine compound is used as a dispersant for dispersing the pigment in a heat-fusible medium. Various metals are known as metal atoms at the center of the compound, and among them, iron phthalocyanine and tin phthalocyanine are particularly preferable.

In the above metal phthalocyanine compounds, iron phthalocyanine and tin phthalocyanine may have one or two chlorine atoms bonded to the central iron or tin atom depending on the production method. Such compounds are also included in the metal phthalocyanine-based compound.

The dispersant is used in an amount of about 5 to 20 parts, preferably about 10 to 15 parts, per 100 parts (parts by weight, hereinafter the same) of the pigment. When the amount of the dispersant is less than the above range, the effect of improving the dispersibility of the pigment cannot be sufficiently obtained, and the improvement of the fluidity of the ink is not sufficient. On the other hand, exceeding the above range is not preferable because the influence on the hue of the final ink becomes large.

The metal phthalocyanine compound used as a dispersant in the present invention has not been expected at all in the past, because it can lower the melt viscosity of the ink and improve the dispersibility of the pigment, thereby increasing the pigment concentration. As a result, the thermal transfer recording medium of the present invention having the above excellent properties has been obtained.

As a material of the heat-fusible medium (hereinafter referred to as a vehicle) in which the pigment is to be dispersed, paraffin wax such as paraffin wax, polyethylene wax, wood wax, beeswax, carnauba wax, microcrystalline wax, ceresin wax Such as natural waxes, furthermore, oxidized waxes, ester waxes, or higher fatty acids such as oleic acid and stearic acid, or waxy substances such as esters thereof, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, vinyl chloride- Synthetic polymers such as vinyl acetate-maleic acid terpolymer, polyvinyl butyral, α-olefin-maleic anhydride copolymer, and petroleum resins are used. These materials may be used alone,
Two or more kinds may be used in combination.

In order to disperse the pigment in a vehicle to form an ink, for example, 4 to 50 parts, preferably 7 to 20 parts, of the pigment are added to 100 parts of the vehicle, and the metal phthalocyanine-based dispersant in the above ratio and a small amount as required. Add other additives of
The mixture is kneaded by passing it through a kneader such as a roll mill or a sand mill several times while being heated to about 90 to 100 ° C. If necessary,
The pigment may be first dispersed in a part of the vehicle, and then the remaining vehicle may be added and uniformly mixed to form an ink.

The obtained ink is applied on a support by hot melt coating. Application amount is about 1-4 g
/ m ^2, and preferably suitably about 1.5 ~2.5g / m ^2. If the coating amount exceeds the above range, the resolution of the printed image will be poor and the high-speed printing compatibility will be poor, and the effect of the present invention will not be exhibited.

In the conventional method, when an attempt is made to disperse the above amount of pigment such as copper phthalocyanine or carbon black, the fluidity at the time of melting deteriorates, and a uniform thin layer can be obtained by hot melt coating. I couldn't hope. In the present invention, the pigment concentration is high, and ink with high fluidity at the time of melting is obtained,
It has become possible for the first time to apply such a thin layer.

The support used in the present invention preferably has a suitable heat resistance and a good thermal conductivity.
For example, a plastic film (a film of polyester, polyethylene, polypropylene, polystyrene, polycarbonate, or the like) having a thickness of about 2 to 10 μm or a high-density paper is used.

A thermal transfer ink layer is provided on one surface of the support, and a silicone resin, a fluororesin, a nitrocellulose resin, or various kinds of lubricity modified by these are optionally provided on the support on the opposite side. A stick prevention layer made of a heat-resistant resin or the like is provided.

As described above, the ink obtained by using an appropriate amount of the dispersant has excellent fluidity when melted.
Further, it has become possible to obtain a thermal transfer recording medium which gives a high-density printed image and has excellent scratch resistance.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

Example 1 16 parts of carbon black and 2 parts of tin phthalocyanine were added to a mixture consisting of 5 parts of carnauba wax, 10 parts of microcrystalline wax, 5 parts of ester wax, 17 parts of petroleum resin and 45 parts of paraffin wax, 100
The ink was obtained by performing a dispersion treatment by passing through a three-roll mill heated to 5 ° C. five times.

The obtained ink was coated on a back surface with a 3.5 μm stick-preventing layer made of silicone-modified urethane resin.
On a polyethylene terephthalate (PET) film having a thickness of m, the composition was applied by hot melt coating to obtain a thermal transfer recording medium. The coating amount of the ink was 2 g / m ² .

Example 2 10 parts of copper phthalocyanine blue and 1 part of tin phthalocyanine were added to a mixture consisting of 5 parts of carnauba wax, 20 parts of microcrystalline wax, 15 parts of ester wax, 5 parts of petroleum resin and 44 parts of paraffin wax. An ink was obtained by performing dispersion treatment in the same manner as in Example 1.

The obtained ink was used in the same PE as in Example 1.
It was coated on a T film in the same manner as in Example 1 to obtain a thermal transfer recording medium.

Example 3 Example 2 was repeated except that 1 part of tin phthalocyanine as a dispersant was replaced by 1 part of iron phthalocyanine in Example 2.
A thermal transfer recording medium was obtained in exactly the same manner as described above.

Example 4 A hot-melt recording medium was obtained in exactly the same manner as in Example 1, except that the ink obtained in Example 1 was applied at a rate of 3 g / m ² .

Comparative Example 1 A hot-melt colored ink was obtained in the same manner as in Example 1 except that tin phthalocyanine as a dispersant was not added. Dispersion of carbon black in this ink was poor.

The ink was applied on a PET film in the same manner as in Example 1 to obtain a thermal transfer recording medium, but in this case, a uniform coated product could not be obtained.

Comparative Example 2 An ink was obtained in the same manner as in Example 1 except that tin phthalocyanine as a dispersant was not added and carbon black as a pigment was reduced to 10.5 parts. A thermal transfer recording medium was obtained by coating on a PET film in the same manner as in Example 1. In this case, uniform coating was difficult.

The ink yield values of the inks obtained in Examples 1 to 4 and Comparative Examples 1 and 2 were measured at a measurement temperature of 90 ° C. using a spread meter manufactured by Yasuda Seiki Seisaku-sho, Ltd. The measurement results are shown in Table 1 together with the types of pigment and dispersant, the content in the ink, and the amount of the ink applied.

[0033]

[Table 1]

From Table 1, it can be seen that the hot-melt colored ink prepared by the method of the present invention using metal phthalocyanine as the dispersant has high fluidity when heated and has excellent coatability.

Using the thermal transfer recording medium obtained in each of the above Examples and Comparative Examples, thermal transfer was performed on a film, and the quality of an image formed by the thermal transfer was evaluated. Evaluation items and evaluation methods are as follows.

Image density: Reflection obtained by measuring an image formed on a Xerox OHP film with a Macbeth reflection densitometer RD-914 using a full-color copier EC-10, a thermal transfer printer manufactured by Fuji Xerox Co., Ltd. Optical density value (OD value). Resolution: The printed image obtained as described above was visually evaluated. ：: The dots are clearly transferred. Δ: Some dots are missing and transferred. C: Many dots are missing and transferred. High speed: thermal transfer printer manufactured by Seiki Industry Co., Ltd., S-Pri
Using 21, a printed image formed at a speed of 11 A4 OHP films / minute was visually evaluated. ：: The dots are clearly transferred. Δ: Some dots are missing and transferred. C: Many dots are missing and transferred. Scratch resistance: The degree of damage of a printed image formed by reciprocating an image formed on an OHP film by reciprocating 50 times with an eraser as in the case of the image density measurement described above. ：: unchanged from before rubbing, without any damage. Δ: Partially abraded image, but practically legible. ×: Abrasion of the image is large and supports reading.

Table 2 shows the evaluation results of the examples and comparative examples.

[0038]

[Table 2]

As can be seen from Table 2, the thermal transfer recording medium of the present invention has a higher image density than that of the comparative example in which no dispersant is used.
It turns out that it has excellent resolution, scratch resistance and high speed.

[0040]

The thermal transfer recording medium of the present invention has a thin ink layer in which pigments are uniformly dispersed, and gives a high density, excellent image resolution and scratch resistance by thermal transfer, and high-speed printing. It is also adaptable.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kiyomi Miyabe 5-4-14 Mundeshima, Nishiyodogawa-ku, Osaka-shi Fuji Chemical Paper Industry Co., Ltd. Technical Center (56) References JP-A-62-77982 (JP, A JP-A-62-222894 (JP, A) JP-A-4-80088 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/38-5/40

Claims (3)

(57) [Claims] 1. A thermal transfer recording medium comprising a heat-meltable colored ink containing a color pigment on a heat-resistant support, which is coated with a heat-meltable ink. A thermal transfer recording medium using a material obtained by dispersing a metal phthalocyanine compound as a dispersant. 2. The thermal transfer recording medium according to claim 1, wherein the coloring pigment is a copper phthalocyanine pigment or carbon black. 3. The metal phthalocyanine-based compound is iron phthalocyanine or tin phthalocyanine.
Or the thermal transfer recording medium according to 2.