JP6217498B2 - Thermal transfer ink sheet - Google Patents

Description

  The present invention relates to a thermal transfer ink sheet of a thermal melt transfer system.

  The thermal transfer ink sheet of the thermal melt transfer system has a structure in which a hot melt ink layer is formed on one side of a base film and a heat resistant slipping layer is formed on the other side. In order to improve sticking resistance and blocking resistance, it has been proposed that such heat-resistant slipping layers contain silicone compounds such as silicone oils and silicone-modified resins that function as lubricants (Patent Documents). 1, 2).

Japanese Patent Laid-Open No. 5-8569 Japanese Patent Laid-Open No. 5-64987

  However, when silicone compounds are used in the heat-resistant slip layer of the thermal transfer ink sheet, the heat-resistant slip, sticking resistance and blocking resistance are improved, but on the other hand, the print quality is reduced and the print quality is reduced. In some cases, the performance of the electronic device, which is an object, is degraded. For example, when the thermal transfer ink sheet is manufactured or stored, since the thermal transfer ink sheet is wound in a roll shape, as a result, the heat-resistant slip layer and the heat-meltable ink layer are overlaid. For this reason, the silicone compound in the heat resistant slipping layer may migrate to the heat-meltable ink layer itself. In such a case, there is a problem that printing failure or adhesion failure of the transferred ink layer occurs. In addition, during heat-melt transfer, volatile low-molecular silicone (for example, cyclic siloxane oligomer), which is an impurity of a silicone compound, may scatter from the heat-resistant slipping layer that is in contact with the heating head and adheres to the transferred portion. When a thermal transfer ink sheet is applied to a precision electronic device, it may cause a printing failure and adhere to a part to be electrically connected (for example, a solder reflow processing unit), resulting in poor connection or reduced conduction reliability. There was a problem of causing. These problems become significant not only due to the migration of migratory substances such as monomer components, oligomer components, and coloring components that remain in the heat-resistant slipping layer of the thermal transfer ink sheet, but also silicone compounds. There are concerns.

  The object of the present invention is to solve the above-mentioned problems of the prior art, and is small from the adverse effect of the migrating substance in the heat-resistant slip layer, and exhibits good sticking resistance and blocking resistance. It is to provide a thermal transfer ink sheet having a conductive layer.

  The present inventors have found that the object of the present invention can be achieved by blending an olefin-based liquid polymer having a specific viscosity as a lubricant in the heat-resistant slip layer of the thermal transfer ink sheet, and to complete the present invention. It came.

  That is, the present invention relates to a thermal transfer ink sheet having a base film, a heat-meltable ink layer formed on one side of the base film, and a heat-resistant slip layer formed on the other side of the base film. A heat transfer ink sheet is provided in which the heat-resistant slip layer contains an olefin-based liquid polymer having a viscosity of 50 mPa · s or more and 10,000 mPa · s or less as a liquid lubricant measured at 25 ° C. according to JIS Z8803.

  The thermal transfer ink sheet of the present invention has a base film, a heat-meltable ink layer formed on one surface thereof, and a heat-resistant slip layer formed on the other surface, and the heat-resistant slip layer is a liquid lubricant. As described above, it contains an olefin liquid polymer having a viscosity of 50 mPa · s or more and 10,000 mPa · s or less measured at 25 ° C. according to JIS Z8803. For this reason, the bad influence by the migratory substance in a heat resistant slipping layer is small, and it can implement | achieve favorable sticking resistance and blocking resistance in a heat resistant slipping layer.

FIG. 1 is a schematic cross-sectional view of the thermal transfer ink sheet of the present invention. FIG. 2 is a schematic sectional view of the thermal transfer ink sheet of the present invention.

  The thermal transfer ink sheet of the present invention will be described in detail with reference to the drawings.

<< Thermal transfer ink sheet >>
An example of the thermal transfer ink sheet of the present invention is shown in FIG. The thermal transfer ink sheet 10 is composed of a base film 1, a hot-melt ink layer 2 formed on one side thereof, and a heat-resistant slip layer 3 formed on the other side of the base film 1. As shown in FIG. 2, a release layer 4 can be provided between the base film 1 and the hot-melt ink layer 2. In the thermal transfer ink sheet 10 of the present invention, the heat-resistant slip layer 3 contains, as a liquid lubricant, an olefin liquid polymer having a viscosity of 50 mPa · s or more and 10,000 mPa · s or less measured at 25 ° C. according to JIS Z8803. Yes. First, the heat resistant slipping layer 3 will be described.

<Heat resistant slip layer 3>
The heat-resistant slip layer 3 is a layer for imparting sticking resistance and blocking resistance to the thermal transfer ink sheet. Therefore, in the present invention, the heat-resistant slip layer 3 contains a liquid lubricant having a predetermined viscosity. In addition, the heat-resistant slip layer 3 can be mixed with a solid lubricant, a heat-resistant resin, an adhesive resin, and an inorganic filler.

(Liquid lubricant)
The liquid lubricant is generally a substance having fluidity at normal temperature (usually 5 ° C. or more and 35 ° C. or less). Specifically, the viscosity measured at 25 ° C. according to JIS Z8803 is 50 mPa · s or more and 10,000 mPa · s or less. Preferably, it is an olefin liquid polymer having a viscosity of 50 mPa · s to 5000 mPa · s. If the olefin-based liquid polymer is in this viscosity range, when the thermal transfer ink sheet is stored in the form of a roll, the liquid lubricant is prevented from transferring to the heat-meltable ink layer 2 and has good sticking resistance and resistance. Blocking properties can be realized.

  The number average molecular weight of such an olefin liquid polymer by GPC method is preferably 500 or more and 5000 or less, more preferably 500 or more and 3000 or less. If the number average molecular weight is within this range, good sticking resistance and blocking resistance can be realized.

  Further, the molecular weight distribution (Mw / Mn) of the olefin-based liquid polymer is preferably 3.0 or less, more preferably 2.4 or less, in order to achieve stabilization of polymer properties and good anti-sticking property.

  Preferable examples of such olefinic liquid polymers include homopolymers or copolymers of α-olefins or mixtures thereof. Of these, α-olefin homopolymers are preferred. Preferred α-olefins include α-olefins having 6 to 21 carbon atoms.

  In addition, the α-olefin copolymer includes a plurality of different α-olefin copolymers, polymerization of one or more α-olefins, ethylene, an acrylate monomer, a methacrylate ester monomer, an alkanoyloxyvinyl monomer, and the like. Preferable examples include a copolymer with a polymerizable unsaturated compound.

  The blending amount of the liquid lubricant in the heat resistant slipping layer is preferably 1% by weight to 30% by weight, more preferably 5% by weight to 20% by weight, based on the total weight of the heat resistant slipping layer, from the viewpoint of improving the sticking resistance. % Or less.

(Solid lubricant)
In the present invention, as described above, in addition to the liquid lubricant, it is preferable to use a solid lubricant in combination for the purpose of improving the transportability of the thermal transfer ink sheet. Here, the solid of the solid lubricant is a substance that generally does not exhibit fluidity at room temperature or lower (usually 5 ° C. or higher and 35 ° C. or lower). Specifically, the lubricant has a melting point measured according to JIS K7121 of 70 ° C. or higher, preferably 90 ° C. or higher and 150 ° C. or lower. As such a solid lubricant, it can be used by appropriately selecting from conventional solid lubricants blended in the heat-resistant slip layer of the thermal transfer ink sheet. Among them, it is preferable to use hydrocarbon synthetic waxes such as Fischer-Tropsch wax, polyethylene wax, and polypropylene wax, and modified products thereof, and particularly acid-modified polyethylene wax can be preferably used.

(Combination of liquid lubricant and solid lubricant)
In the case where the liquid lubricant and the solid lubricant described above are used in combination, when the content of the liquid lubricant in the heat-resistant lubricant layer 3 is x mass% and the content of the solid lubricant is y mass%, the present invention It is preferable that the following relational expressions (1) to (4) are satisfied.

"Formula (1)"
Formula (1) means that the content basis content range of the liquid lubricant in the heat resistant slipping layer 3 is 1% or more and 30% or less. If the lower limit is not reached, the possibility of sticking increases, and if the upper limit is exceeded, the possibility of blocking tends to increase. In addition, from the viewpoint of preventing sticking and blocking, a preferable range of the formula (1) is 5% or more and 20% or less.

"Formula (2)"
Formula (2) means that the mass-based content range of the solid lubricant in the heat resistant slip layer 3 is 1% or more and 30% or less. Outside this range, there is an increased possibility of poor transfer of the thermal transfer ink sheet. Note that the preferable range of the formula (2) is 5% or more and 24% or less from the viewpoint of preventing the occurrence of poor conveyance of the thermal transfer ink sheet.

"Formula (3)"
Formula (3) means that the total content on a mass basis of the liquid lubricant and the solid lubricant in the heat resistant slip layer 3 is 2% or more and 50% or less. Outside this range, the possibility of sticking and poor transfer of the thermal transfer ink sheet increases. From the viewpoint of preventing the occurrence of sticking and thermal transfer ink sheet conveyance failure, the preferred range of Equation (3) is 10% or more and 30% or less.

"Formula (4)"
Formula (4) means that the mass-based content ratio of the liquid lubricant to the solid lubricant is 0.25 or more and 4 or less. Outside this range, the possibility of sticking and poor transfer of the thermal transfer ink sheet increases.

(Other components of heat-resistant slip layer 3)
As already described, the heat-resistant slip layer 3 in the present invention can usually contain a heat-resistant resin, an adhesive resin, and further an inorganic filler in addition to the liquid lubricant.

"Heat resistant resin"
The heat resistant resin is a resin component for imparting heat resistance to the heat resistant slipping layer 3. Here, the term “heat resistance” refers to heat resistance not less than that which does not stick to heating means such as a thermal head during thermal transfer. Specifically, the glass transition temperature measured according to JIS K7121 is preferably 90 ° C. or higher. Indicates a glass transition temperature of 120 ° C. or higher. As such a heat resistant resin, it can be used by appropriately selecting from conventional heat resistant resins blended in the heat resistant slipping layer of the thermal transfer ink sheet. For example, a polyamide resin, a polyimide resin, a polyamideimide resin, a polyester resin, a polyether ether ketone resin, a phenol resin, a cellulose acetate resin, and the like can be given. Among these, cellulose acetate resins, particularly cellulose acetate propionate resins can be preferably used from the viewpoints of solvent solubility, flexibility, and coating characteristics.

  In addition, in the range which does not impair the effect of this invention, in order to provide the heat-resistant slipping layer of a thermal transfer ink sheet with a higher level of heat-resistant slipping, the conventional silicone mix | blended with the heat-resistant slipping layer of a thermal transfer ink sheet System compounds can be blended.

  The content of the heat resistant resin in the heat resistant slip layer 3 is preferably 20% by mass to 97% by mass, and more preferably 40% by mass to 90% by mass. If it is this range, favorable heat resistance can be provided to a heat-resistant slipping layer.

"Adhesive resin"
The adhesive resin is a resin component for imparting adhesiveness to the base film 1 in the heat-resistant slip layer 3. Here, the meaning of “adhesiveness” is that the heat-resistant slip layer 3 is adhered to an extent that does not peel off from the base film 1. Such an adhesive resin is preferably a resin having a glass transition temperature measured in accordance with JIS K7121 of 80 ° C. or more, and is appropriately selected from the adhesive resins blended in the heat resistant slipping layer of the conventional thermal transfer ink sheet. Can be used. For example, an acrylic resin, a polyester resin, a polyurethane resin, etc. can be mentioned. Among these, a polyester resin can be preferably used from the viewpoints of heat resistance, adhesion to a base film, and workability of paint.

  The content of the adhesive resin in the heat resistant slip layer 3 is preferably 1% by mass or more and 40% by mass or less, more preferably 1% by mass or more and 30% by mass or less. If it is this range, the adhesiveness with respect to the base film 1 and heat resistance can be provided to the heat-resistant slipping layer 4.

"Inorganic filler"
The heat-resistant slip layer 3 improves the slip between the heating means such as a thermal head used at the time of thermal transfer and the heat-resistant slip layer 3, and an inorganic filler is used to clean the dust attached to the heating means. Can be contained. As such an inorganic filler, it can select from the conventional inorganic filler mix | blended with the heat-resistant slip layer of a thermal transfer ink sheet suitably, and can be used. For example, alumina, talc, mica, silica, aluminum hydroxide, calcium carbonate, or the like can be used. Of these, talc, mica, aluminum hydroxide, calcium carbonate and the like having a Mohs hardness of less than 5 can be preferably used in order to suppress wear on the surface of a heating means such as a thermal head.

  The particle size of these inorganic fillers is preferably laser diffraction conforming to JIS Z8825-1: 2001 so as not to disturb the slipperiness of the heat resistant slipping layer 3 and to be able to clean the heating means satisfactorily. It is preferable to use those having an average particle size of 0.1 μm or more and 7.0 μm or less measured by an equation particle size distribution analyzer.

  The content of the inorganic filler in the heat-resistant slip layer 3 is preferably 1% by mass or more and 30% by mass or less, more preferably 5% by mass or more and 20% by mass or less. If it is this range, the cleanability with respect to a heating means can be ensured, without inhibiting the slipperiness of the heat-resistant slip layer 4.

Coating amount after drying of the heat-resistant lubricating layer 4 is usually 0.01 g / ^{m 2} or more 1.00 g / ^{m 2} or less, preferably 0.05 g / ^{m 2} or more 0.50 g / ^{m 2} or less.

<Base film 1>
The base film 1 functions as a holding layer for the heat-meltable ink layer 2. As such a base film 1, what is conventionally used as a base film of a thermal transfer ink sheet can be applied. Specific examples of the base film 1 include a polyethylene terephthalate film, a polypropylene film, a polystyrene film, a polyimide film, an aramid film, and a polyamide film. Among these, a polyethylene terephthalate film can be preferably used from the viewpoints of heat resistance and availability.

  The thickness of the base film 1 varies depending on the use of the thermal transfer ink sheet in addition to its strength, heat resistance, thermal conductivity, and thermal expansion coefficient, but is usually 2 μm or more and 12 μm or less, preferably 2 μm or more and 6 μm or less.

<Hot-melting ink layer 2>
The heat-meltable ink layer 2 is softened or melted when heated from the heat-resistant slipping layer 3 side by a heating means such as a thermal head in a state where the heat-meltable ink layer 2 is in contact with the transfer medium, and the softened or melted portion is covered. It is transferred to a transfer body. As such a heat-meltable ink 3, those conventionally used generally as a heat-meltable ink layer of a heat transfer ink sheet can be applied. For example, a heat melting property obtained by dispersing a pigment such as carbon in a solvent dispersion such as toluene in a wax having a melting point of 60 to 120 ° C. adjusted to have a solid content of 5% to 30% by a known method. An ink layer forming paint, a binder made of a base resin such as a polyester resin having a softening point of 100 ° C. or higher and 170 ° C. or lower, and a tackifying resin such as a rosin ester resin having a softening point of 60 ° C. or higher and 160 ° C. or lower; Examples thereof include those formed from a paint having a heat-meltable ink layer formation amount in which a pigment is mixed at a mass ratio of 9: 1 to 5: 5.

The coating amount after drying of the heat-meltable ink layer 3 varies depending on the adhesion between the heat-meltable ink layer 3 and the material of the heat-meltable ink layer 3, but is usually 0.5 g / m ² or more and 3.0 g / m. m ² or less, preferably 0.5 g / m ² or more and 1.5 g / m ² or less.

<Peeling layer 4>
The thermal transfer ink sheet of the present invention is used for facilitating transfer of the heat-meltable ink layer 2 from the base film 1 to the transfer medium during thermal transfer between the base film 1 and the thermal transfer ink layer 2 as necessary. A release layer 4 can be provided as a layer. As such a release layer 4, a release layer that is generally provided between a heat-meltable ink layer of a thermal transfer ink sheet and a base film can be applied. For example, from a blend polymer in which a polyethylene wax having a melting point of 90 ° C. or higher and 130 ° C. or lower and an ethylene-vinyl acetate copolymer having a melting point of 50 ° C. or higher and 80 ° C. or lower are mixed in a mass ratio of 9: 1 to 7: 3. What was formed is mentioned.

The coating amount after drying of the release layer 4 varies depending on the adhesion between the release film 4 and the material of the heat-meltable ink layer 2, but is usually 0.1 g / m ² or more and 3.0 g / m ² or less. It is preferably 0.5 g / m ² or more and 1.5 g / m ² or less.

<< Manufacture of thermal transfer ink sheet >>
The thermal transfer ink sheet 10 of the present invention can be manufactured using a known technique. For example, a coating material for forming a hot-melt ink layer in which a component constituting the hot-melt ink layer 2 is dispersed or dissolved in a solvent such as toluene or MEK by a known method on one surface of the base film 1 is used as a gravure coater or the like. It forms by apply | coating with a well-known coating method, and drying with a well-known method. Next, in addition to the liquid lubricant constituting the heat-resistant slip layer 3, other components such as a heat-resistant resin are added to the other surface of the base film 1, that is, the surface opposite to the surface on which the heat-meltable ink layer 2 is provided. Formed by applying a heat-resistant slipping resin composition for forming a heat-resistant slipping layer dispersed or dissolved in a solvent such as MEK by a known method by a known coating method such as a gravure coater and drying by a known method To do. Thereby, the thermal transfer ink sheet 10 of FIG. 1 can be obtained.

  The thermal transfer ink sheet 10 in FIG. 2 is a release layer forming coating material in which components constituting the release layer 2 are dispersed or dissolved in a solvent such as toluene or MEK prior to the formation of the heat-meltable ink layer 2. Is applied by a known coating method such as a gravure coater, and dried by a known method to form a release layer 4, a hot-melt ink layer 2 is formed thereon, and the base film 1 is further coated. It can be manufactured by forming the heat-resistant slip layer 3 on the other surface.

<< Heat-resistant slipping resin composition >>
The configuration of the heat resistant slipping resin composition suitable for forming the heat resistant slipping layer 3 of the thermal transfer ink sheet 10 of the present invention is the same as or equivalent to the configuration described in the heat resistant slipping layer of the thermal transfer ink sheet of the present invention. is there. Specifically, this heat-resistant slipping resin composition contains, as a liquid lubricant, an olefin liquid polymer having a viscosity of 50 mPa · s or more and 10,000 mPa · s or less measured at 25 ° C. according to JIS Z8803. The content of the liquid lubricant in the heat resistant slipping resin composition is preferably 1% by mass or more and 30% by mass or less on a mass basis excluding the solvent.

  The number average molecular weight of such an olefin liquid polymer by GPC method is preferably 500 or more and 5000 or less, more preferably 500 or more and 3000 or less. Examples of such olefinic liquid polymers include α-olefin homopolymers or copolymers, or α-olefin polymers that are mixtures thereof, with α-olefin homopolymers being preferred. The α-olefin preferably has 6 to 21 carbon atoms. The molecular weight distribution (Mw / Mn) of the olefin liquid polymer is preferably 2.4 or less.

  The heat-resistant slipping resin composition can further contain a hydrocarbon-based synthetic wax having a melting point of 90 ° C. or higher and 150 ° C. or lower as a solid lubricant. As the hydrocarbon synthetic wax, an acid-modified polyethylene wax can be preferably used.

  When the heat-resistant lubricating resin composition contains a solid lubricant in addition to the liquid lubricant, the following relational expression (1) is assumed when the content of the liquid lubricant is x mass% and the content of the solid lubricant is y mass%. ) To (4) are preferably satisfied.

  The heat-resistant slipping resin composition further comprises 20% to 97% by weight of a heat-resistant resin having a glass transition temperature of 90 ° C. or higher according to JIS K7121, and 1% to 40% by weight of an adhesive resin having a glass transition temperature of 80 ° C. or higher. It can be contained in the following.

  Here, as the heat resistant resin, a cellulose acetate resin is preferable, and a cellulose acetate propionate resin is particularly preferable. As the adhesive resin, a polyester resin is preferable.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

Reference Example 1 (Preparation of paint for forming release layer)
8 parts by mass of a polyethylene wax having a melting point of 100 ° C. and 2 parts by mass of an ethylene-vinyl acetate copolymer having a melting point of 65 ° C. are put into a mixed solvent of 70 parts by mass of toluene and 20 parts by mass of MEK, and are dissolved by heat. A release layer-forming coating material was prepared by gradually cooling to room temperature while stirring.

Reference Example 2 (Preparation of paint for forming a hot-melt ink layer)
After 12 parts by mass of a polyester resin having a glass transition temperature of 60 ° C. and 4 parts by mass of a rosin ester resin having a softening point of 95 ° C. are put into a mixed solvent of 40 parts by mass of toluene and 40 parts by mass of MEK and thermally dissolved, The mixture was cooled to room temperature with uniform stirring, and 4 parts by mass of carbon was added to the solution, followed by dispersing the carbon with a disperser to prepare a paint for forming a hot-melt ink layer.

Reference Example 3 (Preparation of a laminate comprising a base film / release layer / hot-melt ink layer)
On one surface of a polyethylene terephthalate film having a thickness of 4.5 μm, the release layer-forming coating material prepared in Reference Example 1 was applied with a gravure coater so that the coating amount after drying was 0.5 g / m ^2. A release layer was formed by drying in a dryer at ° C. On the obtained release layer, the heat-meltable ink layer-forming paint prepared in Reference Example 2 was applied with a gravure coater so that the dry adhesion amount was 1.0 g / m ^2, and a dryer at 60 ° C. It was dried in to form a hot-melt ink layer. This obtained the laminated body which consists of a base film / release layer / heat-meltable ink layer.

Examples 1-7, Comparative Examples 1-4 (Creation of thermal transfer ink sheet)
On the premise that liquid lubricants A to F having the physical properties shown in Table 1 or liquid paraffin are used, the components of the formulation in Table 2 are dissolved in a dissolution vessel, and then cooled to room temperature with stirring and mixing using a dissolver. Thus, a heat resistant slipping resin composition for forming a heat resistant slipping layer was prepared. This heat-resistant slipping resin composition was applied to the opposite surface of the heat-meltable ink layer of the laminate prepared in Reference Example 3 with a gravure coater so that the dry adhesion amount was 0.1 g / m ^2. A thermal transfer ink sheet was obtained by drying in a dryer at 0 ° C. to form a heat-resistant slipping layer.

<< Evaluation >>
Using the obtained thermal transfer ink sheet, a printing test was performed as described below and evaluated from the viewpoint of sticking. In addition, blocking resistance and lubricant migration were evaluated as described below. The obtained results are shown in Table 2.

<Print test>
Printer: Thermal transfer printer Printing resolution: 300 dpi
Print pattern: 5cm x 5cm full surface solid print medium: PP label Temperature and humidity conditions: 23 ° C 65% RH

<Print evaluation>
The printed matter and the thermal transfer ink sheet after printing were visually observed and evaluated according to the following evaluation criteria, and the degree of sticking was ranked in four stages.

Rank: Standard
AA: When no sticking is observed A: When the area ratio of white spots caused by sticking on the printed matter is less than 2% B: The area ratio of white spots caused by sticking on the printed matter is 2% or more and less than 10% Case C: When the area ratio of white spots caused by sticking on the printed matter is 10% or more

<Blocking resistance evaluation>
A thermal transfer ink sheet is slit into a ribbon having a width of 60 mm and a length of 300 m and wound around an ABS core to prepare a sample for evaluation. Samples for evaluation after being stored in a constant temperature layer at 60 ° C. for 96 hours were visually observed and evaluated according to the following evaluation criteria, and the degree of blocking was ranked in four stages.

Rank: Standard
AA: When no blocking occurs at the core part.
A: When a slight blocking occurs in the core part.
B: When blocking partially occurs from the core part to 5 m or less.
C: When blocking occurs even if it exceeds 5 m from the core part.

<Evaluation of impacts due to transition materials such as lubricants>
As described below, the evaluation of the influence due to the transition material such as the lubricant was evaluated by the wetting tension. That is, a 20 μm-thick PET film was coated with the ingredients of the formulation shown in Table 1 using a gravure coater so that the dry adhesion amount was 0.1 g / m ² and dried in a constant temperature layer at 60 ° C. Samples were made by forming layers. An unpainted PET film with a thickness of 20 μm is bonded to the surface of the prepared sample coated with a heat-resistant slip layer, and the film is cut into a 5 cm × 5 cm square, and a 45 ° C. environment is applied while applying a 5 kg load. Hold under 72 hours. Then, the wet tension of the surface opposite to the surface bonded to the remaining uncoated PET film sample from which the sample was peeled was measured according to JIS K6768. The wetting tension approximates the maximum surface tension of the liquid material that can be applied to the surface of the substance, and the larger the wetting tension, the more liquid material with a higher surface tension can be applied. The uncoated PET film itself has a wetting tension (JIS K6768) of 40 mN / m, and in the present invention, it is preferably 36 mN / m or more.

  As can be seen from Table 2, in the thermal transfer ink sheets of Examples 1 to 7, the heat-resistant slipping layer contains an olefin liquid polymer having a viscosity (25 ° C.) in the range of 50 to 10,000 mPa · s as a liquid lubricant. Therefore, a good print evaluation result in which the occurrence of sticking was suppressed was shown. In addition, excellent blocking resistance was exhibited, and the evaluation of influence by a transition material such as a lubricant was also a favorable result. Moreover, it can be seen from the results of Example 7 that preferable results can be obtained even when a silicone-modified polyester resin is used in combination with the olefin liquid polymer as a lubricant.

  On the other hand, since the thermal transfer ink sheet of Comparative Example 1 does not contain any liquid lubricant in the heat resistant slipping layer, the printing evaluation was C evaluation. The thermal transfer ink sheet of Comparative Example 2 containing liquid paraffin as a liquid lubricant was inferior to the Examples in blocking resistance. Since the thermal transfer ink sheet of Comparative Example 3 used a liquid lubricant having a viscosity exceeding 10,000 mPa · s, the state of occurrence of sticking was worse than that of the Example, and the printing evaluation was B evaluation. In addition, the thermal transfer ink sheet of Comparative Example 4 in which the heat-resistant slip layer was composed only of the silicone-modified polyester resin did not cause sticking at all and had good blocking resistance. However, the influence evaluation by a migrating substance such as a lubricant was performed. The wetting tension is considerably smaller than that of the example, and there is a concern that the transferability and adhesion of the hot-melt ink layer may be lowered.

Examples 8-15, Comparative Examples 5-6
The components of the formulation shown in Table 3 were dissolved in a dissolution vessel, and then cooled to room temperature with stirring and mixing using a dissolver to prepare a heat resistant slipping resin composition for forming a heat resistant slipping layer. This heat-resistant slipping resin composition was applied to the opposite surface of the heat-meltable ink layer of the laminate prepared in Reference Example 3 with a gravure coater so that the dry adhesion amount was 0.1 g / m ^2. A thermal transfer ink sheet was obtained by drying in a thermostat at 0 ° C. to form a heat-resistant slipping layer.

  A printing test and blocking resistance were evaluated in the same manner as in Example 1 using the obtained thermal transfer ink sheet. The obtained results are shown in Table 3. Furthermore, the transportability of the thermal transfer ink sheet was evaluated as described below.

<Thermal transfer ink sheet conveyance test>
A thermal transfer ink sheet is set on the thermal transfer printer, and the thermal transfer ink sheet is conveyed 100.0 mm with a feed button of the printer without printing in an environment of 23 ° C. and 65% RH, and then conveyed. The degree of transportability of the thermal transfer ink sheet was ranked into four levels according to the following evaluation criteria.

Rank: Standard
AA: Length of conveyed thermal transfer ink sheet is 99.5 mm or more and 100.0 mm or less A: Length of conveyed thermal transfer ink sheet is 99.0 mm or more and less than 99.5 mm B: Length of conveyed thermal transfer ink sheet Is 98.0 mm or more and less than 99.0 mm C: The length of the conveyed thermal transfer ink sheet is less than 98.0 mm

  From the results of Table 3, since the thermal transfer ink sheets of Examples 8 to 15 satisfy the following formulas (1) to (4), it is a favorable print evaluation result in which sticking is suppressed. The transportability was also good and the blocking resistance was also good.

  On the other hand, the thermal transfer ink sheets of Comparative Examples 5 and 6 do not use a liquid lubricant, and therefore do not satisfy the formula (1). Sheet transportability was also poor.

  The thermal transfer ink sheet of the present invention has a base film, a heat-meltable ink layer formed on one surface thereof, and a heat-resistant slip layer formed on the other surface, and the heat-resistant slip layer is a liquid lubricant. As described above, since the olefin-based liquid polymer having a viscosity of 50 mPa · s or more and 10000 mPa · s or less according to JIS Z8803 is contained, good anti-sticking property and anti-blocking property can be realized. Therefore, it is useful for hot melt transfer recording.

DESCRIPTION OF SYMBOLS 1 Base film 2 Heat-meltable ink layer 3 Heat resistant slipping layer 4 Release layer 10 Thermal transfer ink sheet

Claims (12)

In a thermal transfer ink sheet having a base film, a heat-meltable ink layer formed on one side of the base film, and a heat-resistant slip layer formed on the other side of the base film,
A thermal transfer ink sheet in which the heat-resistant slip layer contains, as a liquid lubricant, an olefinic liquid polymer having a viscosity of 50 mPa · s or more and 10,000 mPa · s or less measured at 25 ° C. according to JIS Z8803.   The thermal transfer ink sheet according to claim 1, wherein the olefin liquid polymer has a number average molecular weight of 500 or more and 5000 or less by GPC method.   The thermal transfer ink sheet according to claim 1 or 2, wherein the olefin liquid polymer is an α-olefin polymer which is a homopolymer or copolymer of α-olefin or a mixture thereof.   The thermal transfer ink sheet according to claim 1 or 2, wherein the olefin liquid polymer is an α-olefin homopolymer.   The thermal transfer ink sheet according to claim 3 or 4, wherein the α-olefin has 6 to 21 carbon atoms.   The thermal transfer ink sheet according to any one of claims 1 to 5, wherein the content of the liquid lubricant in the heat resistant slipping layer is 1% by mass or more and 30% by mass or less.   The thermal transfer ink sheet according to any one of claims 1 to 6, wherein the heat-resistant slip layer further contains a hydrocarbon-based synthetic wax having a melting point of 90 ° C or higher and 150 ° C or lower as a solid lubricant.   The thermal transfer ink sheet according to claim 7, wherein the hydrocarbon-based synthetic wax is an acid-modified polyethylene wax. The following relational expressions (1) to (4) are satisfied when the content of the liquid lubricant in the heat resistant slipping layer is x mass% and the content of the solid lubricant is y mass%. The thermal transfer ink sheet described.

  The heat-resistant slipping layer further comprises 20% by mass to 97% by mass of a heat-resistant resin having a glass transition temperature of 90 ° C. or higher measured according to JIS K7121, and 1% by mass to 40% by mass of an adhesive resin having a glass transition temperature of 80 ° C. or higher. The thermal transfer ink sheet according to any one of claims 1 to 9, which is contained below.   The thermal transfer ink sheet according to claim 10, wherein the heat-resistant resin is a cellulose acetate-based resin, and the adhesive resin is a polyester resin.   The thermal transfer ink sheet according to claim 11, wherein the cellulose acetate resin is a cellulose acetate propionate resin.

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