JPH0444890A - Thermal transfer element - Google Patents

Abstract

PURPOSE:To enable the same process to be applied as for thermally plastic resin by adding thermally plastic resin and solvent-soluble wax having a hydroxyl group in the molecule as a binder in an ink layer. CONSTITUTION:The content of solvent-soluble wax having a hydroxy in the molecule in a binder is preferably be 10 to 20wt.%. If the content of the solvent- soluble wax having a hydroxyl in the molecule in the binder is 10wt.% or less, the resin binder cannot display the effect to eliminate its own defect. If the content of the wax in the binder is 20wt.% or less, the wax binder begins to indicate its defeat, so that the print becomes less resistant to rubbing. The thermally plastic resin which is used as a binder by mixing it with the solvent- soluble wax having a hydroxyl in the molecule is ideal for this type of application and is such as polyamide and an ethylene-vinylacetate copolymer.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a thermal transfer body, Regarding improvements to the binder.

In more detail, [Prior Art] A heat-sensitive transfer body is one in which a heat-melting ink layer is provided on one side of a base material to be melted by heating and transferred onto a transfer target. The constituting ink generally uses a binder whose main component is wax [for example, a technical report by Japan Communication Technology Co., Ltd.].

Since the wax is extremely difficult to dissolve in solvents, when ink is prepared by dispersing pigments in a binder or when the ink is applied to a substrate, it is processed in a heated and molten state.

In addition, the ink using the wax-based binder obtained in this way melts easily when heated by a thermal head and is easily transferred to the transfer target, but it melts too much and printing (in this specification, transfer There are disadvantages such as the transferred images of characters, figures, etc. (printed images) may be unclear, the printing may not be sufficient on paper with a rough surface, or the printing may be susceptible to scratches. Was.

Therefore, in order to eliminate the drawbacks of inks using such wax-based binders, it may be possible to make the main component of the binder a thermoplastic resin that is soluble in solvents. However, due to the strong cohesive force of the binder, it is difficult to release the ink from the substrate during transfer, it is difficult to cut between the ink during transfer, and the melt viscosity is high, so it does not penetrate sufficiently into the transfer target. There was a problem in that the adhesion to the transfer body was insufficient and sharp (that is, high resolution) printing could not be obtained.

[Problem to be solved by the invention]

As mentioned above, in thermal transfer materials having an ink layer using a conventional wax-based binder, there are processing problems in that the ink must be prepared and applied to the substrate in a molten state, and There are problems such as unclear printing or resistance to scratching, and thermal transfer materials with ink layers using resin binders have problems with the release of the ink from the substrate and the ink gap during transfer. There were problems in that the adhesiveness to the object to be transferred was insufficient, making it impossible to obtain sharp prints.

Therefore, the present invention solves the above-mentioned problems of the conventional thermal transfer material, has good processability in preparing the ink and applying the ink to the substrate, and has excellent propertyability and transferability from the ink substrate. An object of the present invention is to provide a heat-sensitive transfer member which has good properties, provides sharp prints, and has excellent durability against rubbing of the prints.

[Means for Solving the Problems] The present invention has achieved the above object by using a solvent-soluble wax having a hydroxyl group in the molecule as a binder component in a heat-sensitive transfer material whose main binder is a thermoplastic resin. It is something.

In other words, the above wax having a hydroxyl group in its molecule is
Since it is soluble in solvents due to its hydroxyl groups, it can be handled in the same way as thermoplastic resins during processing. Therefore, when waxes having hydroxyl groups in their molecules are used in combination with thermoplastic resins as a binder, it is necessary to prepare the ink using a solvent method in which they are mixed in the presence of a solvent, or to form an ink layer on the substrate. Application by solvent coating method is possible.

The solvent-soluble waxes that have hydroxyl groups in their molecules have excellent heat responsiveness similar to paraffin wax and microcrystalline wax, and easily soften and melt when heated. When a solvent-soluble wax with a thermoplastic resin is used in combination with a thermoplastic resin,
Disadvantages of using only thermoplastic resin as a binder include poor releasability from the substrate during transfer, poor separation of ink between printed and non-printed areas during transfer, and poor bonding to the transferred material. Problems such as poor adhesion are eliminated, and the releasability and transferability of the ink from the substrate are improved, making it possible to obtain sharp prints similar to those obtained using a wax-based binder.

In addition, since the binder contains thermoplastic resin, there are problems with printing that is unclear due to excessive melting, poor transferability to rough paper, and durability against scratching when using only a wax-based binder. Bad sex will also be eliminated.

The content of the solvent-soluble wax having a hydroxyl group in the molecule in the binder is preferably 10 to 20% by weight. Content is 1
If it is less than 0% by weight, the effect of eliminating the drawbacks of the resin binder will not be sufficiently exhibited, and if the content of the solvent-soluble wax having a hydroxyl group in the molecule in the binder exceeds 20% by weight, The disadvantages of wax-based binders begin to appear, and the durability of printed characters against scratches decreases.

As the thermoplastic resin used as a binder in combination with the solvent-soluble wax having a hydroxyl group in the molecule, any thermoplastic resin that can be used for this type of use may be used.
For example, polyamide, ethylene-vinyl acetate copolymer,
Examples include ethylene-ethyl acrylate copolymer, styrene-butadiene-styrene block copolymer, aliphatic polycarbonate, aromatic ester-containing polyurethane, lactone type polyester, and solvent-soluble petroleum resin.

The binder is composed of the above-mentioned thermoplastic resin and a solvent-soluble wax having a hydroxyl group in the molecule, but if necessary, a small amount of a dispersant or the like may be added.

The ink is composed of a colorant such as carbon black and a binder, and the amount of the colorant in the ink is usually 15 to 5.
0% by weight. However, since the ink can be prepared by a solvent method, it is prepared as a paint for forming an ink layer in the presence of a solvent, and this paint is applied to one side of the substrate, dried, and then An ink layer is formed by removing the solvent from the paint.

〔Example〕

Next, the present invention will be described in more detail with reference to Examples.

Example 1 A polyethylene terephthalate film with a thickness of 5.5 μm was used as a base, and a heat-resistant back layer made of a silicone-acrylic copolymer was coated on one side of the base made of this polyethylene terephthalate film to a thickness of 0.4 μm. The paint for ink layer formation shown in Table 1 below is applied to the surface of the substrate opposite to the side on which the back layer is provided so that the thickness after drying is 2.1 μm, and dried. A thermal transfer member was produced by forming an ink layer.

Table 1 *1: Byron HT-8200 manufactured by Toyobo Co., Ltd. *2:
POPKO-5000 manufactured by Noda Wax Co., Ltd. is a solvent-soluble wax that has a hydroxyl group in its molecule.

*3: NUC-3170 manufactured by Nippon Unicar *4: MA-8 manufactured by Mitsubishi Chemical Industries, Ltd. *5: Volume ratio of methyl isobutyl ketone to toluene 1
: Mixed solvent of 1 The above paint for forming the ink layer was prepared by dispersing in a ball mill for 100 hours while heating at 35 to 40°C to help dissolve the compounded materials.

The cross-sectional structure of the produced thermal transfer body is schematically shown in the first diagram.
As shown in the figure.

In Figure 1, (1) is a base, and this base (1)
is made of polyethylene terephthalate film. (2) is an ink layer formed on one side of the substrate (1) as described above, and (3) is a heat-resistant back layer made of silicone-acrylic copolymer; 3) is formed on the surface of the substrate (1) opposite to the side on which the ink layer (2) is provided. However, this back layer (3
) is not necessarily necessary if the substrate (1) has sufficient heat resistance.

Example 2 The amount of alcohol wax (alcohol wax refers to a solvent-soluble wax having a hydroxyl group in the molecule; the same applies hereinafter) was increased to 20 parts by weight, and the aromatic ester content was increased to 20 parts by weight. A heat-sensitive transfer member was produced in the same manner as in Example 1, except that the amount of polyurethane was reduced to 60 parts by weight.

Comparative Example 1 An attempt was made to prepare a paint for forming an ink layer by adding the same amount (20 parts by weight) of carnauba wax No. 1 instead of the alcohol wax in the paint for forming an ink layer in Example 1. Even when heated to 40° C., only about 3 to 5 parts by weight of carnauba wax No. 1 was dissolved in the solvent, making it impossible to prepare a paint for forming an ink layer.

Comparative Example 2 An attempt was made to prepare a paint for forming an ink layer by adding the same amount (20 parts by weight) of paraffin wax instead of the alcohol wax in the paint for forming an ink layer in Example 1.
Even when heated to 0℃, paraffin wax remains in the solvent for 3 to 30 minutes.
Only about 5 parts by weight of the solution was dissolved, making it impossible to prepare a paint for forming an ink layer.

Comparative Example 3 A thermal transfer member was produced in the same manner as in Example 1, except that no alcohol wax was blended and the amount of aromatic ester-containing polyurethane was increased to 80 parts by weight.

Comparative Example 4 An ink with a wax-based binder shown in Table 2 was prepared,
A thermal transfer member was produced in the same manner as in Example 1, except that this ink was coated on one side of the same substrate as in Example 1 using a hot melt coating method.

Table 1 Next, using the thermal transfer bodies of Examples 1 to 2 and Comparative Examples 3 to 4 above, a polyethylene terephtha notebook film whose surface was ester-treated was printed using a thermal printer equipped with a thermal head of Energy 301 Ij/Kaku 1. (a) releasability of the ink from the substrate, (b) transferability of the ink to the film, (c) cut-off of print (print resolution)
and (d) printing durability (durability against rubbing of printing). The results are shown in Table 3.
In Table 3, samples with good properties are indicated by G, and samples with poor properties are indicated by NG.

As shown in Table 3, alcohol-based wax (i.e.
The thermal transfer materials of Examples 1 and 2 containing a solvent-soluble wax having a hydroxyl group in the molecule have good ink releasability and transferability, and prints with good sharpness (that is, high resolution). was obtained, and the durability against abrasion of the printed characters was excellent.

On the other hand, in the thermal transfer material of Comparative Example 3, in which the resin-based binder ink does not contain any alcohol-based wax (that is, a solvent-soluble wax having a hydroxyl group in the molecule), the transfer energy was 30 mj/Sono 2. It didn't transcribe at all. In addition, in the thermal transfer material of Comparative Example 4, which used an ink with a wax-based binder, the ink properties and transferability were good, but when the printed surface was rubbed, the ink spread and the durability of the print was affected. The print quality was very poor, and the print quality was also poor due to excessive melting.

〔Effect of the invention〕

As explained above, in the present invention, by using a solvent-soluble wax having a hydroxyl group in the molecule as a binder component of the ink, a paint for forming an ink layer by a solvent method can be prepared, and an ink by a solvent coating method can be prepared. It is possible to apply the layer-forming paint to the substrate, has excellent processability, and has good release and transfer properties of the ink from the substrate, as well as providing sharp prints and eliminating scratches in the prints. It was possible to provide a heat-sensitive transfer member having good durability against.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing an example of a thermal transfer body according to the present invention.

Claims (2)

[Claims] (1) A heat-melting ink layer (2) on one side of the substrate (1)
), wherein the ink layer (2) contains a thermoplastic resin and a solvent-soluble wax having a hydroxyl group in the molecule as a binder. (2) A heat-melting ink layer (2) on one side of the substrate (1)
), wherein the ink layer (2) contains a thermoplastic resin as a binder and a solvent-soluble wax having a hydroxyl group in the molecule; A heat-sensitive transfer material characterized in that the wax content in the binder is 10 to 20% by weight.