JP2014091324A - Thermal transfer sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal transfer sheet printable to a smooth film not subjected to surface treatment such as a film for packaging and further having excellent adhesion, scratch resistance, heat resistance and heat shock resistance in a thermally transferred printed matter.SOLUTION: Provided is a thermal transfer sheet in which the surface of a base material film is at least provided with a release layer, an ink layer and an adhesive layer, and the opposite side thereof is provided with a heat resistant lubricity layer, the adhesive layer comprises a novolak type phenol resin and a polyamide resin in which the softening point (softening point JIS K5601-2-2(1999) by a ring and ball method) lies in the range of 100 to 160°C, and the ink layer comprises a thermoplastic resin in which the softening point (ring and ball method) lies in the range of 75 to 170°C as the main component.

Description

  The present invention relates to a thermal transfer sheet, and more particularly to a thermal transfer sheet that can be printed on various packaging films and that is excellent in adhesion, scratch resistance, heat resistance, and heat shock resistance of a heat-transferred printed matter.

  The thermal transfer sheet of the hot melt transfer system, in which a hot melt ink layer containing a colorant such as pigment and a binder such as resin / wax is provided on a base film, can perform various types of printing easily with a thermal head. Because of its excellent maintainability, it is often used for product management and logistics management by printing barcodes on labels etc. at factories. In recent years, the required performance and applications have diversified, and the need for a thermal transfer sheet excellent in heat resistance, scratch resistance, solvent resistance, etc. of printed matter has been gradually increased. For example, as a thermal transfer sheet excellent in heat resistance, scratch resistance, and solvent resistance, a raw material excellent in heat resistance, scratch resistance, and solvent resistance was used on a base film as shown in Japanese Patent Laid-Open No. 3-169692. A thermal transfer sheet provided with a release layer, a print protection layer, and an ink layer is known.

JP-A-3-166922

  However, in the thermal transfer sheet shown in Patent Document 1, for the transfer medium subjected to surface treatment or surface processing for improving printability such as a label, the printed matter exhibits sufficient performance, When printing is performed on a packaging film having a smooth surface such as a food packaging film, the printed matter cannot be transferred satisfactorily. Even if the printed matter is transferred to the packaging film, the adhesion of the printed matter to the packaging film is poor. If the cellophane tape is attached to the printed matter and then peeled off, the printed matter can be easily removed. There was a problem such as. In an actual factory or the like, a boil treatment and a rapid cooling process may be continuously performed in a sterilization process or the like after printing the expiration date on a food packaging film using a thermal transfer sheet. At that time, if the adhesion between the printed matter and the packaging film is poor, the printed matter is not flexible, or the coating film strength of the printed matter is fragile, the interface between the printed matter and the packaging film respectively It may be destroyed by a stress change (heat shock) caused by the difference in thermal expansion coefficient, and the printed matter may be peeled off from the packaging film, or the printed matter may be cracked or voided. The present invention has been made in view of such a situation, and is capable of printing on various packaging films, and further has a thermal transfer excellent in adhesion, scratch resistance, heat resistance, and heat shock resistance of a heat-transferred printed matter. The invention of the sheet is the main problem.

  In order to solve these problems, the present inventor has provided a release layer, an ink layer, and an adhesive layer on a base material, and in the thermal transfer sheet having a heat resistant slipping layer on the opposite side, the adhesive layer is softened. Point (softening point by ring and ball method JIS K5601-2-2 (1999)) containing novolac-type phenol resin and polyamide resin in the range of 100 to 160 ° C., and ink layer has softening point (ring and ball method) 75 to 170 ° C. The inventors have invented a thermal transfer sheet mainly containing a thermoplastic resin in the range of. According to this configuration, it is possible to provide a thermal transfer sheet that is excellent in transferability to a packaging film and excellent in adhesion of printed matter, scratch resistance, heat resistance, and heat shock resistance.

  Further, by selecting the blending ratio of the novolac type phenol resin and the polyamide resin used in the adhesive layer in the range of 8: 2 to 3: 7 by weight, transferability to various packaging films and adhesion of printed matter. The heat shock resistance can be further improved.

  In addition, by using a dimer acid polyamide resin as the polyamide resin contained in the adhesive layer, it is possible to further improve transferability to various packaging materials, adhesion of printed matter, and heat shock resistance.

  Further, by adding 1-30% of an organic particulate lubricant having an average particle diameter of 1-10 μm and not dissolving in the adhesive layer coating material to the adhesive layer, transferability and printed matter can be obtained. It has become possible to further improve the adhesion and heat shock resistance of

  Further, a polyester resin having a glass transition point Tg (DSC method) of 40 to 90 ° C. and a number average molecular weight Mn of 2000 to 25000 is selected as a thermoplastic resin used as a main component in the ink layer. As a result, it became possible to further improve the scratch resistance and heat resistance of the printed matter.

  According to the present invention, in a thermal transfer sheet having a release layer, an ink layer, and an adhesive layer on a base material and having a heat-resistant slipping layer on the opposite side, a smooth film with no surface treatment such as a packaging film In contrast, it is possible to provide a thermal transfer sheet that is excellent in transferability and excellent in adhesion of printed matter, heat resistance, scratch resistance, and heat shock resistance.

It is typical sectional drawing which shows the thermal transfer sheet which concerns on embodiment of this invention. It is typical sectional drawing which shows the thermal transfer sheet which concerns on embodiment of this invention. It is typical sectional drawing which shows the sea island structure inside the contact bonding layer which concerns on embodiment of this invention.

  As shown in FIG. 1, the thermal transfer sheet 7 of the present invention basically includes a release layer 3 provided on a substrate 4, a thermal melt transfer layer 6 comprising an ink layer 2 and an adhesive layer 1, and a substrate. 4 comprises a heat-resistant slipping layer 5 provided on the opposite side with 4 interposed therebetween, and if necessary, improves the scratching and heat resistance of printing between the ink layer 2 and the release layer 3 as shown in FIG. A heat-resistant printing protective layer 8 may be provided.

  The substrate 4 used in the present invention is not particularly limited as long as it has a certain degree of heat resistance and strength, and a conventionally known material can be appropriately selected and used. Examples of the substrate 4 include a polyethylene terephthalate film (PET), a polypropylene film, a polystyrene film, a polyethylene film, a polyimide film, an aramid film, a polyamide film, a polycarbonate film, and a polyvinyl chloride film. The thickness of these base materials 4 is appropriately considered according to the material so that the strength, heat resistance and thermal conductivity are appropriate, and the range may be 2 to 12 μm, but the thermal conductivity is good. The range of 2 to 6 μm is more preferable for the reason. If the thickness of the base material 4 is less than 2 μm, the heat resistance and strength are inferior and the base material may be broken. Conversely, if the thickness exceeds 12 μm, the strength is sufficient but the thermal conductivity is inferior. Printing failure occurs due to insufficient heat transfer from the head.

  The thermal transfer sheet 7 of the present invention has a base plate 4 for fusing to the head element of the printer during printing to prevent sticking phenomenon in which the base material 4 is wrinkled and breakage of the base material 4 due to heat. Mainly various known heat-resistant resins such as silicon resin, fluorine resin, nitrocellulose resin, silicon-modified urethane resin, silicon-modified acrylic resin, and polyamide-imide resin are opposite to the surface of the material 4 on which the release layer 3 is applied. A heat resistant slipping layer 5 made of a raw material and a mixture of a curing agent and a lubricant as an auxiliary material may be provided.

The coating amount of the heat-resistant slip layer 5 may be arbitrarily selected from the range of 0.05 to 0.50 g / m ² depending on the use situation and the type of printer, but the reason for cost and performance stability To 0.10 to 0.20 g / m ² is more preferable. When the coating amount is less than 0.05 g / m ² , the expected heat resistance effect cannot be obtained. Conversely, when the coating amount is 0.5 g / m ² or more, problems such as foil dropping occur.

  The paint for the heat resistant slipping layer 5 is prepared by dissolving the main raw material in various organic solvents and thoroughly stirring and mixing with other auxiliary raw materials with a dissolver or the like.

  There are no particular restrictions on the method of coating the heat-resistant slip layer 5, and various known coating methods such as bar coating, spray coating, slit reverse coating, direct gravure coating, reverse gravure coating, and offset gravure coating are appropriately selected. The coating material may be formed by coating the base material 4 with the paint by the above-described method and evaporating and drying the organic solvent with a dryer.

  The release layer 3 used in the present invention is appropriately selected so that the melting point (DSC method) or softening point (ring and ball method) of the entire release layer 3 is in the range of 80 to 170 ° C., more preferably 100 to 130 ° C. There is no particular limitation as long as a known hot-melt material or thermoplastic resin is selected and configured. When the melting point (DSC method) or softening point (ring and ball method) of the adhesive layer 3 is less than 80 ° C., the heat resistance tends to decrease. Conversely, the melting point (DSC method) and softening point (ring and ball method) are 160 ° C. or higher. In this case, a large amount of heat is required to melt the release layer during printing, which may cause blurring of printing and poor transfer.

  It is preferable to use various known waxes as the hot-melt material of the release layer 3. Since the wax is hard at room temperature, it does not reduce the scratch resistance of the printed matter. Further, it melts at the time of heating and has a very low viscosity, which has the effect of improving the foil sharpness and releasability of the transfer layer 6.

  Examples of the wax include, but are not limited to, carnauba wax, montanic acid wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene wax, polyolefin wax, amide-modified wax, and fluorine-modified wax. There is nothing. You may use the said wax individually or in mixture of multiple.

  If necessary, the release layer 3 may contain various known thermoplastic resins in combination with wax. The type of thermoplastic resin is soft and flexible, and has the effect of preventing the transfer layer from falling off by giving appropriate adhesiveness between the substrate 4 and the transfer layer 6, and the tailing phenomenon of printing. Resins that can prevent the above and obtain the effect of clear printing are preferable.

  Examples of the thermoplastic resin include ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, polyvinyl acetate, polyamide resin, polyester Examples thereof include, but are not limited to, resins, polyurethane resins, and adhesive polyolefin resins. The thermoplastic resins may be used alone or in combination.

  The ratio of the wax and the thermoplastic resin contained in the release layer 3 is not particularly limited, but may be appropriately selected from the range of 95: 5 to 5:95 by weight according to necessity.

  In addition, the release layer 3 may contain various known surfactants, fillers, and lubricants as auxiliary materials as needed, and may improve and adjust the viscosity, foil breakability, and paintability.

The coating amount of the release layer 3 may be appropriately selected from the range of 0.1 to 3.0 g / m ² depending on the required quality, and is 0.3 to 1.5 g / in terms of cost and performance stability. it is more preferably selected from the range of m ^2. If the coating amount of the release layer 3 is less than 0.1 g / m ² , a sufficient ink layer release property cannot be obtained and transfer failure occurs. On the contrary, when the coating amount of the release layer 3 exceeds 3.0 g / m ² , the sensitivity of the print layer becomes insufficient, or the release layer component transferred to the printed matter increases, resulting in a coating film on the printed matter. Strength and heat resistance will deteriorate.

  The coating material for the release layer 3 is prepared by sufficiently stirring and mixing a material obtained by melting the main raw material with heat, dissolving or dispersing in various organic solvents, or emulsifying in water with other auxiliary materials. Furthermore, if necessary, it may be prepared by appropriately dispersing the particle size of the non-dissolved material with various known dispersers (for example, bead mill, pin mill, etc.).

There are no particular restrictions on the coating method of the release layer 3, and various known coating methods such as bar coating, spray coating, slit reverse coating, direct gravure coating, reverse gravure coating, offset gravure coating, etc. are appropriately selected. A coating film may be formed by applying a paint on a substrate and evaporating and drying an organic solvent with a dryer.
In the case of a heat-melted paint, it is also possible to select a method such as hot melt gravure coating or hot melt die coating to form a coating film.

  In the present invention, an ink layer 2 mainly composed of various known colorants such as pigments and dyes and a binder component is provided between the release layer 3 and the adhesive layer 1. The addition amount of the colorant is preferably appropriately selected from the range of 10 to 50% of the total weight of the ink layer according to the usage situation. When the addition amount is less than 10%, the print density of the printed matter is not sufficient, and when it exceeds 50%, the transfer property of the print is adversely affected.

  The ink layer 2 used in the present invention is particularly limited as long as it is mainly composed of a thermoplastic resin having a softening point (ring ball method) of 75 to 170 ° C., more preferably 100 to 160 ° C. However, a conventionally known material can be appropriately selected and used. When the softening point (ring and ball method) is less than 75 ° C., the heat resistance is drastically lowered. On the other hand, when the softening point (ring and ball method) is 170 ° C. or higher, a large amount of heat is required for the release layer to melt during printing, which causes blurring of printing and poor transfer.

  As a thermoplastic component used for the ink layer 2, it is preferable to use a thermoplastic resin having a strong cohesive force and having heat resistance and coating strength as a main component. Examples of such thermoplastic resins include polyester resins, polyurethane resins, polyamide resins, acrylic resins, phenol resins, coumarone resins, ketone resins, styrene resins, terpene resins, and their modified resins or copolymers. Examples include, but are not limited to, a coalesced resin. The thermoplastic resins may be used alone or in combination. As the thermoplastic resin used in the present invention, a polyester resin having particularly excellent heat resistance and coating strength is particularly preferable.

  More preferably, the glass transition point Tg (DSC method) of the polyester resin is appropriately selected from the range of 40 to 90 ° C. When the glass transition point Tg (DSC method) is 40 ° C. or lower, the heat resistance and the coating strength of the printed matter gradually decrease, and therefore the printed matter is likely to be lost when the printed matter comes into contact with something. The problem occurs. On the contrary, if the glass transition point Tg (DSC method) exceeds 90 ° C., a large amount of energy is required for printing, which causes blurring of printing and poor transfer.

  The number average molecular weight Mn of the polyester is preferably in the range of 2000 to 25000, more preferably in the range of 5000 to 20000. If the number average molecular weight Mn is less than 2000, the heat resistance of the printed matter and the coating film strength of the printed matter are weak. Conversely, if the number average molecular weight Mn exceeds 25,000, the coating strength of the printed matter becomes too strong, and the foil breakage at the time of printing. Negatively impacts.

  Waxes may be added to the ink layer 2 as an auxiliary material in order to improve the foil cutting property and the thermal sensitivity. Examples of the wax include carnauba wax, montanic acid wax, paraffin wax, microcrystalline wax, Fischer-Tropsch wax, and polyethylene wax, but are not particularly limited thereto. The waxes may be used alone or in combination.

  The melting point (DSC method) of the wax added to the ink layer may be appropriately selected from the range of 80 to 160 ° C. according to the application, but more preferably is in the range of 100 to 130 ° C. The amount added is preferably 20% or less of the total weight of the ink layer. If the amount of the wax added exceeds 20% of the total weight of the ink layer, the adhesion strength of the printed matter to the printing medium will suddenly decrease or the coating strength will be weakened.

  The ink layer 2 may appropriately contain various known surfactants and fillers as auxiliary materials to improve and adjust the dispersibility of the colorant, the ink foil breakage, the paint viscosity, and the like.

The coating amount of the ink layer 2 may be appropriately selected from 0.5 to 3.0 g / m ² depending on the required quality, but is 1.0 to 2.0 g / m from the viewpoint of cost and performance stability. ^It is more preferable to select from the range of ² . If the coating amount is less than 0.5 g / m ² , sufficient printing density and coating film strength cannot be obtained. On the other hand, when the coating amount exceeds 3.0 g / m ² , the printing sensitivity and the foil cutting property are rapidly deteriorated.

  The coating material for the ink layer 2 is obtained by sufficiently stirring and mixing a colorant and other auxiliary materials with a dissolver or the like in a material in which a binder component is dissolved in various known organic solvents or emulsified in water. Thereafter, in order to disperse and color the colorant and the like, it may be prepared by appropriately dispersing with various known dispersers (for example, bead mill and pin mill).

  There are no particular restrictions on the coating method of the ink layer 2, and various known coating methods such as bar coating, spray coating, slit reverse coating, direct gravure coating, reverse gravure coating, offset gravure coating, and the like can be selected as appropriate. What is necessary is just to paint on the material and evaporate and dry the organic solvent with a dryer.

  In the present invention, an adhesive layer 1 containing both a phenol resin and a polyamide-based resin is provided on the ink layer 2 in order to improve the adhesion to the printing medium.

  The types of phenol resins are largely classified into resol type phenol resins and novolac phenol resins. As the phenol resins used in the present invention, novolac type phenol resins are particularly preferable. The resol type phenolic resin is a thermosetting resin, and further self-curing, so that various physical properties change with time, and handling is difficult. On the other hand, the novolac type phenol resin is a thermoplastic resin and is easy to handle because it is not self-curing. Novolac type phenolic resin has high coating film hardness, excellent moisture resistance, heat resistance, and scratch resistance, and also has high cohesive strength, so it has excellent adhesion to various packaging films and is suitable for the present invention. Resin.

  The softening point (ring and ball method) of the phenol resin is preferably selected as appropriate from the range of 100 to 160 ° C, more preferably from 110 to 150 ° C. When the softening point (ring and ball method) is less than 100 ° C., the heat resistance and scratch resistance of the printed matter rapidly decrease. On the other hand, if the softening point (ring and ball method) exceeds 160 ° C., the energy at the time of printing is insufficient, and problems such as blurred printing and insufficient adhesion strength occur.

  The type of the polyamide resin is not particularly limited. For example, a polyamide resin obtained by polycondensation reaction of ω amino acids, a fatty acid polycondensation polyamide resin obtained by cocondensation polymerization of a higher fatty acid and a polyamine, and homonylon monomers are copolymerized. It may be appropriately selected from copolymerized nylon and an elastomer containing the above-described resin structure, but it is preferable to select a polyamide-based resin that dissolves in a solvent and has a relatively low softening point from the viewpoint of processability. In the present invention, it is particularly preferable to use a dimer acid polyamide resin which is particularly excellent in adhesion to various packaging material films, moisture resistance, heat resistance, flexibility and the like.

  The softening point (ring and ball method) of the polyamide-based resin is preferably selected as appropriate from the range of 100 to 160 ° C, more preferably from 110 to 150 ° C. When the softening point (ring and ball method) is less than 100 ° C., the heat resistance and scratch resistance of the printed matter rapidly decrease. On the other hand, if the softening point (ring and ball method) exceeds 160 ° C., the energy at the time of printing is insufficient, and problems such as blurred printing and insufficient adhesion strength occur.

Generally, a solubility parameter (SP value) is used as a measure for estimating the adhesion between objects. In general, it is considered that the closer the SP values are to each other, the easier the adhesion is, but the structure in the polymer such as the crystallinity of the resin and hydrogen bonds also affects the adhesion. Packaging films include low-polarity polyolefin films such as polyethylene and polypropylene and high-polarity films such as nylon and PET. Since the dimer acid polyamide resin has a long-chain alkyl group with low polarity in the composition, the SP value is close to the SP value of the polyolefin film, and exhibits excellent adhesion to the polyolefin film and the like. At the same time, since it has a highly polar amide group, it has excellent adhesion to highly polar nylon, PET and the like. Although other polyamide resins are excellent in adhesion to nylon and PET, the length of the alkyl group is shorter than that of dimer acid polyamide, so the SP value is high and the adhesion to polyolefin films and the like is poor. In addition, since dimer acid polyamide resin is amorphous, it has excellent flexibility, strong impact resistance and coating strength, very good moisture resistance, is easily dissolved in solvents, and has excellent workability. It has excellent characteristics.
Therefore, it is particularly preferable to use a dimer acid polyamide resin formed by condensation polymerization of dimer acid and polyamine as the polyamide resin used in the present invention.

  The blending ratio of the phenol resin and the polyamide-based resin may be appropriately selected from the range of 8: 2 to 3: 7, and more preferably 7: 3 to 6: 4. Transferability and adhesion to packaging film are not sufficient with both phenolic resin and polyamide resin alone, but transfer to various packaging films by mixing two resins and selecting the above blending ratio The present inventor has found that the properties and adhesion are significantly improved. As for the tendency of individual resins, a larger amount of phenol resin is excellent in printing sharpness and heat resistance, but if it is too much, adhesion, transferability and flexibility tend to deteriorate. Conversely, the more the polyamide-based resin, the better the printing sensitivity, the transferability and the flexibility. However, if the amount is too much, the heat resistance and the printing sharpness tend to deteriorate, and at the same time, the transferability and adhesion are also deteriorated.

  You may add the particulate lubricant which consists of organic substance to the contact bonding layer 1 as needed. For the organic particulate lubricant to be added, it is necessary to select a raw material that does not dissolve in the solvent used for the coating material of the adhesive layer 1. Examples of such organic particulate lubricants include carnauba wax, montanic acid wax, Fischer-Tropsch wax, paraffin wax, polyethylene wax, polypropylene wax, amide-modified wax, fluorine-modified wax, silicone-modified wax, and the like, and Resins and elastomers such as fluororesin powder, silicon resin powder, and silicon rubber powder are exemplified, but not limited thereto. Further, the lubricant may be added alone, or a plurality of lubricants may be mixed and used as necessary.

  The lubricant added to the adhesive layer 1 is uniformly dispersed inside the adhesive layer 1 to form a sea-island structure as shown in FIG. Since the adhesive layer 1 has a sea-island structure, the foil cutting property at the time of printing is improved, and at the same time, the particulate lubricant that appears on the surface of the adhesive layer is also effective in preventing blocking. When a lubricant such as carnauba wax or polyethylene wax is melted at the time of printing and a wax lubricant compatible with the binder component of the adhesive layer 1 is added to the adhesive layer 1, it melts at the time of printing and the printing sensitivity is increased. It has the effect of improving the adhesion strength by improving the wettability. When a resin or elastomer lubricant that is not melted and incompatible with the binder component of the adhesive layer 1 is added to the adhesive layer 1 during printing such as fluororesin powder or silicon resin powder, the sea-island structure is maintained even in the printed matter. This contributes to lowering the elastic modulus of the printed matter, and has an effect of making it difficult for the coating film on the printed matter to be destroyed even with a stress change due to heat shock.

  The shape of the organic particulate lubricant is not particularly limited and may be indefinite, but a spherical diameter is more preferable. The average particle size of the organic particulate lubricant is not particularly limited, but is preferably 1 to 10 μm, and is desirably selected as appropriate from 10 times or less, more preferably 2 times or less the thickness of the adhesive layer 1. If the average particle size of the organic particulate lubricant is 1 μm or less, the effect of cutting off the foil and the effect of lowering the elastic modulus of the coating film will not appear sufficiently. Resulting in. Furthermore, when the average particle diameter is larger than 10 times the thickness of the adhesive layer 1, transferability and adhesion to the packaging film tend to be lowered.

  The melting point (DSC method) of the wax lubricant is not particularly limited among the organic particulate lubricants, but it is desirable to appropriately select from the range of 80 to 160 ° C., more preferably 100 to 150 ° C. If the melting point (DSC method) of the wax lubricant to be added is less than 80 ° C., the heat resistance of the printed matter is remarkably lowered, and if it exceeds 160 ° C., the print sensitivity expected to be improved may not be expected.

  The organic particulate lubricant is added in an amount of 1 to 30%, more preferably 5 to 20% of the total weight ratio of the adhesive layer 1. If the addition amount is less than 1%, the expected effect of the lubricant to be added is not obtained at all. If the addition amount exceeds 30%, the transferability and adhesion to the packaging film are deteriorated, and the coating film strength is rapidly reduced. End up.

  The adhesive layer 1 may contain various known surfactants and fillers as auxiliary materials as appropriate to improve and adjust the dispersibility of the lubricant, foil breakage, paint viscosity, and the like.

The coating amount of the adhesive layer 1 may be appropriately selected from 0.1 to 1.5 g / m ² depending on the required quality, but is 0.1 to 1.0 g / m from the viewpoint of cost and performance stability. ^It is more preferable to select from the range of ² . Adhesiveness to the packaging film that is expected to be less than 0.1 g / m ² applied to the adhesive layer 1 becomes insufficient. On the contrary, when the application amount of the adhesive layer 1 exceeds 1.5 g / m ² , the heat resistance is gradually weakened.

  The paint for the adhesive layer 1 is prepared by dissolving the binder component in various known organic solvents and then thoroughly stirring and mixing the organic particulate lubricant and other auxiliary materials with a dissolver. The organic solvent that dissolves the binder must be selected so as not to dissolve the organic particulate lubricant.

  There are no particular restrictions on the coating method of the adhesive layer 1, and various known coating methods such as bar coating, spray coating, slit reverse coating, direct gravure coating, reverse gravure coating, offset gravure coating, and the like can be selected as appropriate. What is necessary is just to paint on the material and evaporate and dry the organic solvent with a dryer.

  Next, an example is given and the present invention is explained concretely.

(Example 1 base material and heat-resistant slip layer)
With a gravure coater, a silicon resin was applied to one side of a 4.5 μm thick polyethylene terephthalate film (PET film) and dried to form a heat resistant slipping layer having a coating amount of 0.2 g / m ² .

(Example 1 release layer)
The release layer coating 1 shown below is applied on the opposite side of the PET film on the surface coated with the heat-resistant slip layer by a gravure coating machine, and dried to provide a release layer having a coating amount of 1.0 g / m ^2. Formed.

(Release layer coating 1)
Ingredient Part by weight • Polyethylene wax (melting point 110 ° C., density 0.92) in toluene dispersion (solid content 10%) 90.0
-Ethylene-vinyl acetate copolymer (melting point 72 ° C) dissolved in toluene (solid content 10%) 10.0
The release layer coating 1 includes a wax dispersion obtained by hot-melting polyethylene wax in toluene in a melting pot and then slowly cooling the solution to room temperature. The polymer (EVA) was melted in toluene and then dissolved in a resin, which was cooled to room temperature, and then stirred and mixed with a dissolver. If necessary, the wax dispersion may be pulverized to an appropriate particle size by a bead mill or the like.

(Example 1 ink layer)
On the release layer, the ink layer paint 1 shown below was applied with a gravure coater and dried to form an ink layer having a coating amount of 1.0 g / m ² .

(Ink layer paint 1)
Ingredient Weight part / polyester resin (softening point 95 ° C., Tg 65 ° C., Mn 16000) 3.8
Styrene resin (softening point 120 ° C) 3.8
・ Carbon 2.0
-Toluene dispersion of polyethylene wax (melting point 110 ° C, density 0.92) (solid content 10%) 4.0
Toluene 43.2
・ Methyl ethyl ketone 43.2
In the ink layer coating 1, a polyester resin and a styrene resin are dissolved in a mixed solvent of toluene and methyl ethyl ketone, and then a toluene dispersion of polyethylene wax and carbon are added and sufficiently stirred and mixed with a dissolver. Finally, carbon or the like is dispersed and colored using a dispersing machine such as a bead mill.

(Example 1 adhesive layer)
The adhesive layer paint 1 shown below was applied on the ink layer with a gravure coater and dried to form an adhesive layer having an application amount of 0.5 g / m ² .

(Adhesive layer coating 1)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 8.0
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C.) 2.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The adhesive layer coating 1 is prepared by dissolving each resin in toluene and isopropyl alcohol.

  Example 2 has the same conditions except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 2 described below.

(Adhesive layer paint 2)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 6.0
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C.) 4.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 1.

  Example 3 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the following adhesive layer coating material 3.

(Adhesive layer coating 3)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C) 3.0
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C.) 7.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 1.

  Example 4 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 4 described below.

(Adhesive layer coating 4)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 7.2
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C) 1.8
・ Polyethylene wax powder (melting point 125 ° C., particle size 7 μm) 1.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The adhesive layer coating 4 is prepared by dissolving each resin in toluene and isopropyl alcohol, adding polyethylene wax, and thoroughly stirring and mixing with a dissolver.

  Example 5 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 5 described below.

(Adhesive layer coating 5)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 5.4
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C.) 3.6
・ Polyethylene wax powder (melting point 125 ° C., particle size 7 μm) 1.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 4.

  Example 6 is the same as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 6 described below.

(Adhesive layer coating 6)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 2.7
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C.) 6.3
・ Polyethylene wax powder (melting point 125 ° C., particle size 7 μm) 1.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 4.

  Example 7 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 7 described below.

(Adhesive layer coating 7)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 8.0
Dimer acid polyamide resin (softening point 138 ° C) 2.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The adhesive layer coating 1 is prepared by dissolving each resin in toluene and isopropyl alcohol.

  Example 8 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 8 described below.

(Adhesive layer coating 8)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 6.0
Dimmer acid polyamide resin (softening point 138 ° C) 4.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 1.

  Example 3 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 9 described below.

(Adhesive layer coating 9)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C) 3.0
Dimer acid polyamide resin (softening point 138 ° C.) 7.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 1.

  Example 10 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the adhesive layer coating material 10 described below.

(Adhesive layer coating 10)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 7.2
-Dimer acid polyamide resin (softening point 138 ° C) 1.8
・ Polyethylene wax powder (melting point 125 ° C., particle size 7 μm) 1.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The adhesive layer coating 10 is prepared by dissolving each resin in toluene and isopropyl alcohol, adding polyethylene wax, and thoroughly stirring and mixing with a dissolver.

  Example 11 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 11 is replaced with the following adhesive layer coating material 11.

(Adhesive layer coating 11)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 5.4
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C.) 3.6
・ Polyethylene wax powder (melting point 125 ° C., particle size 7 μm) 1.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 4.

  Example 12 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the following adhesive layer coating material 12.

(Coating layer coating 12)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 2.7
Fatty acid-based polycondensation polyamide resin (softening point 138 ° C.) 6.3
・ Polyethylene wax powder (melting point 125 ° C., particle size 7 μm) 1.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 4.

  Example 13 has the same conditions as Example 11 except that the ink layer coating material 1 of Example 11 is replaced with the ink layer coating material 2 described below.

(Ink layer paint 2)
Component Weight part / Polyester resin (softening point 110 ° C., Tg 16 ° C., Mn 6000) 3.5
Styrene resin (softening point 120 ° C) 3.5
・ Carbon 2.0
・ Toluene dispersion of polyethylene wax (melting point 110 ° C., density 0.92) (solid content 10%) 10.0
・ Toluene 40.0
・ Methyl ethyl ketone 41.0
The paint preparation method is the same as that of the ink layer paint 1.

<Comparative Example 1>
Comparative Example 1 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the following adhesive layer coating material 13.

(Adhesive layer coating 13)
Ingredient Weight part, novolac type phenolic resin (softening point 90 ° C.) 6.0
・ Dimer acid polyamide resin (softening point 115 ° C.) 4.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 1.

<Comparative example 2>
Comparative Example 2 has the same conditions as Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the following adhesive layer coating material 14.

(Adhesive layer coating 14)
Ingredient Weight part, novolac type phenolic resin (softening point 120 ° C.) 10.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 1.

<Comparative Example 3>
Comparative Example 3 has the same conditions as in Example 1 except that the adhesive layer coating material 1 of Example 1 is replaced with the following adhesive layer coating material 16.

(Adhesive layer coating 15)
Ingredient Weight part / dimer acid polyamide resin (softening point 115 ° C.) 10.0
・ Toluene 30.0
・ Isopropyl alcohol 60.0
The paint preparation method is the same as that of the adhesive layer paint 1.

<Comparative Example 4>
Comparative Example 4 has the same conditions as Example 11 except that the ink layer coating material 1 of Example 11 is replaced with the ink layer coating material 3 described below.

(Ink layer paint 3)
Component Weight part / Polyester resin (softening point 95 ° C., Tg 65 ° C., Mn 16000) 3.5
Petroleum resin (softening point 70 ° C) 3.5
・ Carbon 2.0
・ Toluene dispersion of polyethylene wax (melting point 110 ° C., density 0.92) (solid content 10%) 10.0
・ Toluene 40.0
・ Methyl ethyl ketone 41.0
The paint preparation method is the same as that of the ink layer paint 1.

<Comparative Example 5>
Comparative Example 5 has the same conditions as Example 1 except that the adhesive layer was not painted in Example 1.

<Printing conditions>
Printing was performed on the surface layer of the packaging film under the following conditions using the thermal transfer sheets obtained in the above Examples and Comparative Examples.
Printer: SMRATED SD3C (made by Markem)
Print resolution: 300 dpi
Printing speed: 150mm / sec
Print density: 140%
Printed material: ONY / LLDPE
Surface untreated biaxially stretched nylon film (surface layer) / linear low density polyethylene wax (heat seal layer)

<Evaluation of printing>
Print samples prepared under the above print conditions were evaluated under the following conditions.
◎ ... Good (no transfer failure at all), ○ ... Yes (transfer failure is a little in details), △ ... No (partial transfer failure and print blurring are seen), × ... Defective (no transfer at all)

<Evaluation of adhesion>
The adhesion evaluation method is generally referred to as a cellotropic test. Specifically, a cellophane tape having a width of 18 mm is pressed with a roller having a weight of 200 g so that air does not enter the print surface of the print sample. Leave it for 1 hour or more after it has been put into close contact. Thereafter, the bonded cellophane tape is peeled off at a peeling angle of 90 ° and a tensile force of 4.9N. Evaluation was made under the following conditions based on the traces of the prints attached to the cellophane tape after peeling.
◎ ... Good (printing is almost impossible), ○ ... possible (printing is thin), △ ... impossible (printing is clearly removed), × ... defect (printing is almost complete) )

<Evaluation of scratch resistance>
Scratch resistance was evaluated based on the following conditions based on the state of printing after applying a 1 cm diameter ABS resin ball to the printing surface with a point load of 500 g and making 50 reciprocations per second. did.
◎ ・ ・ ・ Good (no missing prints / print deformation), ○ ・ ・ ・ Yes (no missing prints / small print deformation), △ ・ ・ ・ No (small print missing / large print deformation), × ・ ・ ・ Bad (Large missing print / large deformation)

<Evaluation of heat resistance>
The heat resistance is evaluated by molding the packaging material into a bag shape with the print side of the print sample facing up, filling it with water and boiling it in boiling water for 1 hour, Evaluation was performed under the following conditions based on the state of printing after rubbing the printed part 10 times with a point load of 200 g with the attached cotton cloth.
◎ ... Good (no print deformation), ○ ... Yes (print deformation small), △ ... No (print deformation), × ... Bad (large print deformation)

<Heat shock resistance>
The heat shock resistance was evaluated by forming a packaging material into a bag shape with the printing surface of the printed sample front side, filling it with water, boiling it in boiling water for 30 minutes, and then boiling the bag. The print sample is immediately put into ice water from hot water, rapidly cooled for 10 minutes or more, taken out, and the print surface is wiped off with cotton cloth while rubbed it 20 times. Evaluation was performed under the following conditions based on the state of printing after repeating this process twice.
◎ ・ ・ ・ Good (no missing print, no decrease in print density), ○ ・ ・ ・ possible (small print missing, no decrease in print density), △ ・ ・ ・ No (less print, small change in print density), × ..Defective (large print missing, large change in print density)

  Samples were prepared by printing on packaging films using the thermal transfer sheets obtained in the examples and comparative examples, and based on the evaluation methods described above, printing, adhesion, scratch resistance, heat resistance, heat seal resistance The results of the evaluation are shown in Table 1 below.

  From the results of Table 1, when the thermal transfer sheets of Examples 1 to 13 were used, the transferability of printing on the packaging film was good, and the heat resistance, scratch resistance, adhesion resistance, and heat shock resistance were excellent. . On the other hand, when the thing (90 degreeC) with a low softening point (ring ball method) of a novolak-type phenol resin is used for the contact bonding layer 1 like the comparative example 1, heat resistance and heat shock resistance fell. Further, as in Comparative Examples 2 and 3, when only one of the novolak type phenol resin and the polyamide resin was used for the adhesive layer 1, the printing was not transferred to the packaging film. Moreover, when the thing (70 degreeC) with a low softening point (ring ball method) of a thermoplastic resin was used for the ink layer 2 like the comparative example 4, heat resistance and heat shock resistance fell. Further, as in Comparative Example 5, unless the adhesive layer 1 was applied, the printing was not transferred to the packaging material film.

  When Examples 1-6 and Examples 7-12 are compared, it turns out that adhesiveness, abrasion resistance, and heat shock resistance are improving clearly by changing a polyamide-type resin to dimer acid polyamide. In addition, when Examples 1 to 3 and Examples 4 to 6 are compared, by adding an organic particulate lubricant to the adhesive layer, print transferability, adhesion, scratch resistance, heat shock resistance, and the like are improved. It was confirmed that there was a tendency. Similarly, when the glass transition point Tg (DSC method) of the polyester resin contained in the ink layer 2 is low (15 ° C.) as in Example 11, the scratch resistance, heat resistance, and heat shock resistance are reduced. It was confirmed that there was a tendency.

  The thermal transfer sheet of the present invention can be used not only for printing on general distribution labels, but also for printing on a wide variety of packaging films, as well as adhesion, heat resistance, and scratch resistance to various packaging films. Because it is excellent in heat resistance and heat shock resistance, it can be used for food packaging materials and heat-resistant retort foods in the processes that require heat sterilization from the printing for displaying the expiration date and contents on various food packaging materials. Can be used in a wide range of applications up to printing on packaging materials.

DESCRIPTION OF SYMBOLS 1; Adhesive layer 2; Ink layer 3; Release layer 4; Heat-resistant base film 5; Heat-resistant slip layer 6; Transfer layer 7; Thermal transfer sheet 8; Heat-resistant printing protective layer 9; )
10: Binder component of the adhesive layer (sea part)

Claims (5)

  In a thermal transfer sheet having at least a release layer, an ink layer, and an adhesive layer on a base film, and a heat-resistant slipping layer provided on the opposite side, the adhesive layer has a softening point (softening point by ring and ball method JIS K5602-1-2- 2 (1999)) Contains a novolac-type phenolic resin and a polyamide-based resin in the range of 100 to 160 ° C., and the ink layer contains a thermoplastic resin as a main component in the softening point (ring and ball method) range of 75 to 170 ° C. Heat transfer sheet.   2. The thermal transfer sheet according to claim 1, wherein a mixing ratio of the novolac type phenol and the polyamide-based resin contained in the adhesive layer is in a range of 8: 2 to 3: 7 by weight ratio.   The thermal transfer sheet according to claim 1 or 2, wherein the polyamide-based resin contained in the adhesive layer is a dimer acid polyamide resin.   The organic particulate lubricant having an average particle diameter in the range of 1 to 10 μm that does not dissolve in the solvent used in the adhesive layer coating is contained in the range of 1 to 30% by weight ratio of the entire adhesive layer. The thermal transfer sheet according to 1 to 3.   The thermoplastic resin used as a main component in the ink layer is a polyester resin, and has a glass transition point Tg (DSC method) of 40 to 90 ° C and a number average molecular weight Mn of 2000 to 25000. The thermal transfer sheet described in 1.

Images