JPH02192993A - Medium for thermal transfer recording - Google Patents

Abstract

PURPOSE:To ensure that a highly compatible and subsequently, temporally extremly stable composition or a coat is obtained by adding a specific percent by weight of polyester resin and chlorinated paraffin within a specific melting point or softening point range to ink. CONSTITUTION:This medium for thermal transfer recording has transferrable heat-melting ink applied one side of a substrate. In addition, the medium contains 15 to 70 percent by weight of polyester resin within a softening point or melting point range of 55 to 120 deg.C and 1 to 20 percent by weight of chlorinated paraffin within a melting point or softening point range of 55 deg.C in ink. If the polyester resin can be used at a melting point or a softening point of 55 to 120 deg.C for heat-transferrable ink, it is acceptable regardless of its type. However, the preferable type of the resin is crystalline polyester resin with a number average molecular weight of 500 to 6,000 and a melting point range of 55 to 120 deg.C, or low crystalline or non-crystalline polyester resin with a glass transition point of 30 to 100, a softening point of 55 to 120 deg.C and an endothermic amount of 10cal/g or less due to a crystal fusion.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a heat-sensitive recording medium that transfers a recorded image by heating, and more specifically, the present invention relates to a heat-sensitive recording medium that transfers a recorded image by heating. This invention relates to a heat-sensitive recording medium with excellent control.

[Problems to be solved by conventional technology and inventions] The thermal transfer recording method uses an extremely thin base film (mainly a few microns).
polyethylene terephthalate (PET) film)
It is constructed by applying heat-melting ink made of various resins, wax, carbon black, etc. As thermal transfer printers have been developed in various fields in recent years, various properties have been required of ink as a recording medium. As a result, the number of types of resins, waxes, etc. used has increased, and there is a need to make good use of some components that are essentially not suitable for thermal transfer printing systems.

Even in the application of polyester resins to thermal transfer inks, which are expected to have a variety of functions, problems have been observed due to incompatibility of physical properties. One is the case of using a linear polyester resin that is sharp melt and is expected to have functionality such as low printing energy and multiple printing. In this case, since the polyester resin used is crystalline, the coating film becomes brittle and the strength of the coating film decreases. As a result, productivity decreases in post-processing steps such as slitting and rewinding, and paper surface contamination and powder falling due to ribbon end surfaces during printing occur. Furthermore, when a polyester resin with a high melt viscosity is used, especially a glass-like polyester resin that is expected to have good print fastness, rough surface printing, etc., the melt viscosity becomes extremely high, often resulting in poor transfer.

Conventional technology deals with these problems by adding ordinary oils, plasticizers, etc. in the same way as with ordinary resins (Japanese Patent Application Laid-open No. 62-1989-1).
(See Publication No. 13383). However, when considering combinations with polyester resins, problems remain with respect to compatibility, etc., and no product has been obtained that satisfies all of the above requirements.

[Means to solve the problem]

The present inventors have made extensive studies to solve these problems, and as a result, have arrived at the present invention.

That is, the present invention provides a thermal transfer recording medium in which transferable heat-melt ink is coated on one side of a base material, in which 15 to 70 weight of a polyester resin having a melting point or softening point range of 55 to 120° C. is added to the ink. %, and the melting point or softening point is 5
The present invention provides a thermal transfer recording medium characterized by containing 1 to 20% by weight of chlorinated paraffin having a temperature of less than 5°C.

The polyester resin used in the present invention may be any polyester resin as long as it has a melting point or softening point in the range of 55 to 120"C and can be used in thermal transfer inks. However, in particular, a polyester resin with a number average molecular weight of 500 to 6
000, a crystalline polyester resin with a melting point range of 55 to 120°C, or a low crystalline resin with a glass transition point of 30 to 100°C, a C1 softening point of 55 to 120°C, and an endothermic amount due to melting of crystals of 10 cal/g or less Amorphous polyester resins are preferred.

The crystalline polyester resin described above is synthesized by a polycondensation reaction between a polyhydric alcohol and a polyhydric carboxylic acid, preferably a dioxy compound and a dibasic acid, its lower alcohol ester, or its acid anhydride. Examples of dibasic acids include oxalic acid, malonic acid, geltaric acid, adipic acid, pimelic acid, azelaic acid, cepacic acid, succinic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedioic acid, and diglycolic acid. , n-
Examples include butylsuccinic acid, isobutylsuccinic acid, n-octylsuccinic acid, isooctylsuccinic acid, n-dodecylsuccinic acid, isododecylsuccinic acid, hexahydroterephthalic acid, and the like.

Examples of dioxy compounds include ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, ■, 7-
Hebutanediol, 1,8-octanediol, 1,9
-nonanediol, 1゜10-decanediol, undecamethylene glycol, dodecamethylene glycol, tridecamethylene glycol, tetradecamethylene glycol, octadecamethylene glycol, eicosamerethylene glycol, neopentyl glycol, diethylene glycol, triethylene glycol, Tetraethylene glycol, hexaethylene glycol, glycerol,
Examples include pentaerythritol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, cyclohexane dimetatool, and the like.

In addition, in the present invention, it is also possible to use the polyester resin described above with ethylenically unsaturated bonds introduced therein. The polyhydric carboxylic acid containing an ethylenically unsaturated bond constituting the polyester resin, which may have a bond introduced therein, is, for example, a dibasic acid having 4 to 24 carbon atoms containing an ethylenically unsaturated bond (for example, fumaric acid, maleic acid, itaconic acid,
Citraconic acid, traumatic acid, Intermediate oil manufacturing (7) UL
B-20, IPU-22 and its lower alcohol esters and acid anhydrides, etc.), polymerized fatty acids obtained by polymerizing drying oil or semi-drying oil fatty acids (e.g. tall oil fatty acids, etc.) generally called dimer acids, Examples include alkenylsuccinic acids and their acid anhydrides such as butenylsuccinic acid, octenylsuccinic acid, and dodecenylsuccinic acid, muconic acid, polybutadiene dicarboxylic acid, tetrahydrophthalic acid, and its acid anhydrides.

Furthermore, as polyhydric alcohols containing ethylenically unsaturated bonds constituting the polyester resin, 1,4-butynediol, polybutadiene diol (hydrogenated product of dimer acid), and the above-mentioned ethylenically unsaturated bonds containing Reaction product of polyhydric carboxylic acid and alkyl glycidyl ether (
Examples include compounds obtained by the reaction shown by the following reaction formula.

(In the formula, R represents an alkylene group containing an ethylenically unsaturated bond, and R1 represents an alkyl group.) Examples of the aforementioned low crystallinity or non-crystalline polyester resin include phthalic acid,
Phthalic anhydride, isophthalic acid, terephthalic acid, hexahydrophthalic anhydride, malonic acid, succinic acid, curtaric acid,
Saturated dibasic acids such as adipic acid and cepatic acid, unsaturated dibasic acids such as maleic anhydride, fumaric acid, itaconic acid, and tetrahydrophthalic anhydride, or dimer acids obtained by trimerizing riluic acid, etc., and ethylene glycol. , Engineering, 2
-propylene glycol, 1,6-hexanediol,
Alternatively, polyester resins obtained by polycondensation of bisphenol compounds and diols such as propylene oxide adducts and ethylene oxide adducts thereof may be mentioned.

The aforementioned polyester resins may be used individually in combination with chlorinated paraffin, or may be mixed and further combined with chlorinated paraffin to form a three-component system. Of course, it is also possible to use it in combination with a third component other than the polyester resin and chlorinated paraffin.

In the present invention, the melting point or softening point range is 55 to 120
℃ polyester resin is blended in the ink in an amount of 15 to 70% by weight. If this amount is less than 15% by weight, the low energy properties and robustness inherent to polyester resins will be insufficient. Moreover, if it exceeds 70% by weight, the amount of colorant and binder will be relatively reduced, which will cause problems in terms of coloring power and film-forming properties.

The chlorinated paraffin used in the present invention is chlorinated paraffin wax or normal paraffin.
Any material having a melting point or softening point of less than 55° C. can be used. However, if you expect a clear effect from the introduction of chlorine groups, the chlorine content should be between 10 and 75.
The chlorine content is preferably 30% by weight or more, and more preferably 30% by weight or more. Furthermore, when solubility or ease of handling are important, liquid or low melting point chlorinated paraffins are desirable.

In the present invention, the amount of chlorinated paraffin added is preferably 1 to 20% by weight in the ink; if it is less than 1% by weight, the addition does not exhibit the effects of improving flexibility, improving compatibility, etc. If it is added in an amount exceeding 20% by weight, the coating film will become too soft and there is a concern that problems may arise in environmental resistance, which is not preferable.

The polyester resins described in this invention perform specifically in combination with the chlorinated paraffins described in this invention. Combinations of softeners and thinners and polyester resins, which can be easily inferred from the prior art, did not provide performance comparable to that of the present invention. In particular, the combinations of the invention are characterized by good compatibility, resulting in formulations or coatings that are extremely stable over time.

The ink constructed according to the present invention can be applied to a substrate as a solvent-based paint dissolved or dispersed in a solvent or as a true melt paint to form a thermal transfer recording medium such as a thermal transfer ink sheet.

As the base material used in the present invention, resin films such as polyethylene terephthalate, polycarbonate, polyethylene, polystyrene, polypropylene, and polyimide, which are used in conventional thermal recording media, are suitably used.

(Examples) The effectiveness of the present invention will be shown below by Examples, but the present invention is not limited to these Examples.

The polyester resin and chlorinated paraffin used in the examples are shown below.

Crystalline polyester resin (1): Decanediol adibate, melting point 75°C, average molecular weight 3,000 Crystalline polyester resin (2): Hexanedioldodecadiacid, melting point 68°C, average molecular weight 2,000 Crystalline polyester resin (3): Ethylene glycol cedar Patic acid melting point 72°C 1 average molecular weight 1700 Amorphous polyester resin (1): Bisphenol A glycol ester glass transition point 6
7℃1 Softening point 101'C Number average molecular weight 1700, Heat of fusion Ocal/g Chlorinated paraffin (1): Chlorination rate 40-42%, Freezing point -20''C Chlorinated paraffin (2): Chlorination rate 64~ 67%, freezing point 45°C Example 1 Attritor MA of the formulation shown in Table 1 at 90°C.
-01C (manufactured by Mitsui Miike Kakoki) to obtain a hot melt ink. This ink was applied onto a 5.7 μm thick PET film (Toshi Lumirror) by hot melt coating to a coating weight of 7.5 g/n+'' to prepare a thermal transfer ink sheet.

Table 1 Table 2 Example 2 The formulation shown in Table 2 was added to a mixed solvent of toluene/methyl ethyl ketone/cyclohexanone = 5/3/2 at a solid content ratio of 30.
% and kneaded with a sand mill (Dyno Mill X [IL type, manufactured by Shinmaru Enterprises) to obtain a solvent-based ink. This was coated on a PET film (Toshi Lumirror) with a thickness of 3.5 μm at a coating thickness of 4.5 g/m” to prepare a thermal transfer ink sheet.

Example 3 The formulation shown in Table 3 was kneaded in the same manner as described in Example 2, and further coated in the same manner as described in Example 2 to prepare a thermal transfer ink sheet.

Table Comparative Example 1 The formulation shown in Table 4 was kneaded in the same manner as in Example 2,
Furthermore, a thermal transfer ink sheet was prepared by coating in the same manner.

The results are shown in Table 5, and the coating film strength was significantly improved by the addition of chlorinated paraffin, and it was confirmed that the coating film was softened by the chlorinated paraffin.

Table 5 Comparative Example 2 The formulation shown in Table 6 was made into a paint and applied in the same manner as in Example 2 to obtain a thermal transfer ink sheet.

Table Test Example 1 The coating strength of the ink sheets obtained in Examples 1 to 3 and Comparative Example 1 was evaluated by a repeated bending test. That is, strip-shaped samples each having a width of 30 mm and a length of 100 mm were cut out, and subjected to a bending test 50 times, and the shedding of the ink coating film at the bent portions was evaluated in terms of area %. The evaluation was performed on two types of film strength: immediately after the film was formed, and 20 days after the film was formed, taking into account changes over time.

Table 6 The obtained ink sheet contained a large amount of liquid chlorinated paraffin, so the coating film was smeared, and when printing was performed with a printer, a large amount of background staining occurred. Blocking problems also occurred at room temperature, and it became clear that the ink formulation was not practical as an ink sheet.

Example 4 The formulation shown in Table 7 was added to a mixed solvent of toluene/methyl ethyl ketone/cyclohexanone = 5/3/2 at a solid content ratio of 30.
% and kneaded with a sand mill (Dyno Mill KDL type manufactured by Shinmaru Enterprises) to obtain a solvent-based ink.

Table 7 Table Comparative Example 3 The formulation shown in Table 8 was made into a paint in the same manner as in Example 4,
A solvent-based ink was obtained.

Test Example 2 The solvent-based inks obtained in Example 4 and Comparative Example 3 were distilled off to obtain an ink with a solid content of 100%, and the melt viscosity was measured (E-type viscometer/120'C/shear rate 0. IS-'
).

The results are shown in Table 9.

Table 9 As shown above, the ink melt viscosity was reduced by adding chlorinated paraffin.

Due to this effect, when an ink containing chlorinated paraffin is actually printed using a printer, the coverage rate increases and the dot reproducibility improves.

Claims (1)

[Claims] 1. A thermal transfer recording medium in which transferable heat-melt ink is coated on one side of a base material, in which a polyester resin having a melting point or softening point range of 55 to 120° C. is added to the ink.
70% by weight, and 1 to 20% by weight of chlorinated paraffin having a melting point or softening point of less than 55°C. 2. Polyester resin has a number average molecular weight of 500 to 6000
The thermal transfer recording medium according to claim 1, which is a crystalline polyester resin having a melting point range of 55 to 120°C. 3. Polyester resin has a glass transition point of 30-100℃,
The thermal transfer recording medium according to claim 1, which is a low-crystalline or non-crystalline polyester resin having a softening point of 55 to 120°C and an amount of heat absorbed due to melting of crystals of 10 cal/g or less. 4. Chlorine content of chlorinated paraffin is 10 to 75% by weight
The thermal transfer recording medium according to claim 1.