JP7159698B2 - heat transfer sheet - Google Patents

Description

The present invention relates to thermal transfer sheets.

Conventionally, energy is applied from the back layer side using a thermal head or the like to a thermal transfer sheet comprising a back layer, a substrate such as a resin film, and a transfer layer having a colored layer containing a coloring material. 2. Description of the Related Art A thermal fusion transfer method is known in which a printed matter is produced by transferring a transfer layer onto a transfer material such as paper or a plastic sheet and forming an image thereon.
Since images formed by the thermal fusion transfer method have high density and excellent sharpness, the method is suitable for recording binary images such as characters and line drawings. Further, according to the thermal fusion transfer method, variable information such as address, customer information, numbering, bar code, etc. can be recorded on the transferred material using a computer and a thermal transfer printer.

The thermal transfer sheet used for producing the printed matter is generally required to have high adhesion to a transfer medium and high blocking resistance such that adhesion does not occur when the sheet is rolled up and stored.

By the way, in recent years, for the purpose of improving the productivity of printed matter, the development of a thermal transfer printer capable of transferring a transfer layer provided in a thermal transfer sheet onto a transfer material at a high printing speed (about 50 m/min.) has progressed. When the thermal transfer sheet of No. 1 is used at a high printing speed, the formed image has defects and blurring, and the quality of the printed matter is significantly deteriorated.

In addition, when the transfer layer is transferred at a high speed, the damage to the back layer is greater than when the transfer is performed at a normal printing speed (approximately 30 to 40 m/min.). In some cases, this may cause omission or blurring.

The present invention has been made in view of the above problems, and the problem to be solved is to provide a thermal transfer sheet having excellent high-speed transfer aptitude, head residue prevention, adhesion to a transfer receiving material, and blocking resistance. It is to be.

The thermal transfer sheet of the present invention comprises a transfer layer having a colored layer, a substrate, and a back layer,
The colored layer contains an ethylene-vinyl acetate copolymer, a terpene resin, a polyolefin and a coloring agent,
a back layer comprising a filler;
The ratio of the average particle size of the filler to the thickness of the back layer (average particle size of the filler/thickness of the back layer) is 0.8 or more and 3.5 or less.

In one embodiment, the filler has an average particle size of 0.05 μm or more and 1.5 μm or less.

In one embodiment, the filler content in the back layer is 1% by mass or more and 10% by mass or less.

In one embodiment, the thickness of the back layer is between 0.03 μm and 1 μm.

In one embodiment, the back layer includes at least one of a (meth)acrylic resin and a silicone-modified (meth)acrylic resin.

In one embodiment, the ethylene-vinyl acetate copolymer melt flow rate is 100 g/10 min. Above 1000g/10min. It is below.

In one embodiment, the softening point of the terpene resin is 70°C or higher and 140°C or lower.

In one embodiment, the polyolefin has a melting point of 50° C. or higher and 140° C. or lower.

In one embodiment, the thickness of the transfer layer is between 0.5 μm and 2.5 μm.

According to the present invention, it is possible to provide a thermal transfer sheet having excellent high-speed transfer aptitude, head residue prevention, adhesion to a transfer-receiving body, and blocking resistance.

1 is a schematic cross-sectional view showing one embodiment of a thermal transfer sheet of the present invention; FIG. 1 is a schematic cross-sectional view showing one embodiment of a thermal transfer sheet of the present invention; FIG.

(Thermal transfer sheet)
The thermal transfer sheet 10 of the present invention comprises, as shown in FIG.
In one embodiment, the transfer layer 12 further comprises a release layer 15 below the colored layer 11, as shown in FIG.
Furthermore, in one embodiment, the thermal transfer sheet 10 of the present invention may further include a release layer and a primer layer on the substrate (not shown).

Each layer included in the thermal transfer sheet according to the present invention will be described below.

(Base material)
The base material has heat resistance to withstand the thermal energy applied during thermal transfer (for example, heat from a thermal head), and has mechanical strength and solvent resistance to support the colored layer, etc. provided on the base material. If so, you can use it without any restrictions.

Examples of base materials include polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), 1,4-polycyclohexylene dimethylene terephthalate, terephthalic acid-cyclohexanedimethanol-ethylene glycol copolymer, and the like. polyester, polyamides such as nylon 6 and nylon 6,6, polyolefins such as polyethylene (PE), polypropylene (PP) and polymethylpentene, polyvinyl chloride, polyvinyl alcohol (PVA), polyvinyl acetate, vinyl chloride-vinyl acetate Copolymers, vinyl resins such as polyvinyl butyral and polyvinylpyrrolidone (PVP), (meth)acrylic resins such as polyacrylate, polymethacrylate and polymethyl methacrylate, imide resins such as polyimide and polyetherimide, cellophane, cellulose acetate , cellulose resins such as nitrocellulose, cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB), styrene resins such as polystyrene (PS), polycarbonates, and films composed of ionomer resins (hereinafter simply “ "Resin film") can be used.
Among the above resins, polyesters such as PET and PEN are preferable, and PET is particularly preferable, from the viewpoint of heat resistance and mechanical strength.
In the present invention, "(meth)acryl" means to include both "acryl" and "methacryl". Moreover, "(meth)acrylate" means to include both "acrylate" and "methacrylate".

Moreover, the laminated body of the above-mentioned resin film can also be used as a base material. A laminate of resin films can be produced by using a dry lamination method, a wet lamination method, an extrusion method, or the like.

When the substrate is a resin film, the resin film may be a stretched film or an unstretched film. It is preferred to use

The thickness of the substrate is preferably 2 μm or more and 25 μm or less, more preferably 3 μm or more and 10 μm or less. Thereby, the mechanical strength of the substrate and the transmission of thermal energy during thermal transfer can be improved.

(transfer layer)
The transfer layer included in the thermal transfer sheet of the present invention includes at least a colored layer. Also, in one embodiment, the transfer layer further comprises a release layer below the colored layer.

The thickness of the transfer layer is more preferably 0.5 μm or more and 2.5 μm or less, more preferably 0.8 μm or more and 2.2 μm or less, and particularly preferably 1.2 μm or more and 2.2 μm or less. Thereby, the high-speed transfer aptitude of the thermal transfer sheet of the present invention can be further improved. Furthermore, the abrasion resistance (hereinafter simply referred to as abrasion resistance) of printed matter produced from the thermal transfer sheet of the present invention can be improved.

(Colored layer)
The thermal transfer sheet of the present invention comprises a colored layer containing an ethylene-vinyl acetate copolymer, a terpene resin, a polyolefin and a coloring agent.

In the present invention, the ethylene-vinyl acetate copolymer is a copolymer obtained by copolymerizing an ethylene monomer and a vinyl acetate monomer. Other monomers other than monomers can be included. The proportion of structural units derived from the other monomer in the ethylene-vinyl acetate copolymer is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less. preferable.

The melt flow rate (MFR) of the ethylene-vinyl acetate copolymer was 100 g/10 min. Above 1000g/10min. It is preferably less than 300g/10min. Above 800g/10min. The following are more preferable. Thereby, the high-speed transfer aptitude of the thermal transfer sheet of the present invention can be further improved.
In the present invention, MFR is measured in accordance with JIS K 7210 under conditions of a temperature of 190°C and a load of 2.16 kg.

The proportion of structural units derived from a vinyl acetate monomer in the ethylene-vinyl acetate copolymer (hereinafter referred to as vinyl acetate composition proportion) is preferably 10% by mass or more and 35% by mass or less, and 14% by mass or more. It is more preferably 30% by mass or less. Thereby, the high-speed transfer aptitude of the thermal transfer sheet of the present invention can be further improved.
In addition, in this invention, a vinyl acetate composition ratio is measured based on JISK7192 using a Fourier-transform infrared spectrophotometer.

Also, the colored layer can contain two or more ethylene-vinyl acetate copolymers.

The content of the ethylene-vinyl acetate copolymer in the colored layer is preferably 5% by mass or more and 30% by mass or less, more preferably 8% by mass or more and 23% by mass or less. Thereby, the high-speed transfer aptitude of the thermal transfer sheet of the present invention can be further improved.

In the present invention, the terpene resin is a polymer of terpene monomers, and examples of terpene monomers include α-pinene, β-pinene, dipentene, limonene, myrcene, alloocimene, ocimene, α-phellandrene, and α-terpinene. , γ-terpinene, terpinolene, 1,8-cineole, 1,4-cineole, α-terpineol, β-terpineol, γ-terpineol and sabinene.

Further, in the present invention, the terpene resin includes modified terpene resins, such as aromatic modified terpene resins, which are copolymers of terpene monomers and aromatic monomers.
Examples of aromatic monomers include styrene, α-methylstyrene, p-styrene, 3,4-dimethylstyrene, o-divinylbenzene, p-divinylbenzene, α-chlorostyrene, p-chlorostyrene, 2,4- dichlorostyrene, vinyltoluene, 1-vinylnaphthalene and the like.

Moreover, in the present invention, the terpene resin includes a terpene phenol resin which is a copolymer of a terpene monomer and a phenol monomer.
Phenolic monomers include, for example, phenol, cresol, xylenol, catechol, resorcin, hydroquinone, bisphenol A, and the like.

In addition, the terpene resin can contain monomers other than the above-mentioned monomers within a range that does not impair the characteristics of the present invention. The proportion of structural units derived from the other monomers in the terpene resin is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less.

Also, the colored layer can contain two or more terpene resins.

The softening point of the terpene resin is preferably 70°C or higher and 140°C or lower, more preferably 90°C or higher and 120°C or lower. Thereby, the high-speed transfer suitability and blocking resistance of the thermal transfer sheet of the present invention can be further improved.
In addition, in this invention, the softening point of terpene resin is measured based on JISK7234.

The content of the terpene resin in the colored layer is preferably 5% by mass or more and 30% by mass or less, more preferably 7% by mass or more and 25% by mass or less, and 8% by mass or more and 23% by mass or less. is more preferred. Thereby, the high-speed transfer suitability and blocking resistance of the thermal transfer sheet of the present invention can be further improved.

In the present invention, polyolefin is a polymer of α-olefin monomers, and examples of α-olefin monomers include ethylene, propylene, 1-butene, isobutylene, 1-pentene, 1-hexene and the like.
Moreover, the polyolefin may contain monomers other than the α-olefin monomer as long as the characteristics of the present invention are not impaired. The content of the other monomer is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

The melting point of the polyolefin is preferably 50° C. or higher and 140° C. or lower, more preferably 75° C. or higher and 140° C. or lower. As a result, the thermal transfer sheet of the present invention can be further improved in its suitability for high-speed transfer, head residue prevention and anti-blocking properties.
In the present invention, the melting point of polyolefin is measured according to JIS K 7121.

The polyolefin content in the colored layer is preferably 10% by mass or more and 40% by mass or less, more preferably 15% by mass or more and 35% by mass or less. Thereby, the high-speed transfer aptitude and adhesion of the thermal transfer sheet of the present invention can be further improved.

The colored layer contains at least one colorant. The coloring material is not particularly limited, and is preferably selected appropriately according to the desired color tone, and inorganic pigments, organic pigments, dyes, and the like can be used. For example, when it is desired to form a bar code image, it is preferable to use a material that has sufficient black density and does not discolor or fade due to light, heat, or the like. Examples of such coloring materials include carbon black such as lamp black, graphite, and nigrosine dyes.

The content of the coloring material in the colored layer is preferably 10% by mass or more and 60% by mass or less, and more preferably 15% by mass or more and 50% by mass or less. As a result, the density of the image formed on the transferred material can be improved while maintaining the high-speed transfer suitability, head residue prevention, adhesion and blocking resistance of the thermal transfer sheet of the present invention.

The colored layer may contain a resin material other than the ethylene-vinyl acetate copolymer, terpene resin and polyolefin within the range that does not impair the properties of the present invention. Examples thereof include polyamide, vinyl resin, (meth)acrylic resin, imide resin, cellulose resin and styrene resin.

The colored layer may contain additives such as fillers, plasticizers, antistatic agents, ultraviolet absorbers, inorganic particles, organic particles, release agents and dispersing agents, as long as the properties of the present invention are not impaired.

The thickness of the colored layer is preferably 0.2 μm or more and 2 μm or less, more preferably 0.5 μm or more and 1.5 μm or less. Thereby, the high-speed transfer aptitude and adhesion of the thermal transfer sheet of the present invention can be further improved.

The colored layer is formed by dispersing or dissolving the above material in water or an appropriate solvent, and coating the material by known means such as roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating and rod coating. , to form a coating film on a substrate or the like, and then drying the film.

(back layer)
The thermal transfer sheet of the present invention comprises a back layer containing at least one filler on the side of the substrate on which the transfer layer is not provided.

The filler contained in the back layer may be an organic filler, an inorganic filler, or a combination thereof.
Examples of organic fillers include particles containing resin materials such as melamine resins, benzoguanamine resins, (meth)acrylic resins, polyamides, fluororesins, phenolic resins, polyolefins, and silicone resins.
Inorganic fillers include clay minerals such as talc and kaolin, carbonates such as calcium carbonate and magnesium carbonate, hydroxides such as aluminum hydroxide and magnesium hydroxide, sulfates such as calcium sulfate, and oxides such as silica. , graphite, saltpeter, and boron nitride.
Among the above, particles containing a resin material are preferable, particles containing at least one of a melamine resin and a benzoguanamine resin are more preferable, and particles containing a melamine resin and a benzoguanamine resin are even more preferable, from the viewpoint of head residue prevention and blocking resistance. .

The shape of the filler may be spherical, elliptical, cylindrical, prismatic, or the like, and is preferably spherical from the viewpoint of head residue prevention and blocking resistance.
The sphericity of the filler is preferably 1 or more and 1.3 or less, more preferably 1 or more and 1.1 or less.
In the present invention, the sphericity ratio means the longest diameter/shortest diameter of the filler.

Moreover, the surface of the filler may be treated with a surface treatment agent such as a silane coupling agent.

The average particle size of the filler is preferably 0.05 μm or more and 1.5 μm or less, more preferably 0.1 μm or more and 1.2 μm or less, and particularly preferably 0.1 μm or more and 1.0 μm or less. . As a result, the head residue prevention property and anti-blocking property of the thermal transfer sheet of the present invention can be further improved.
In the present invention, the average particle size means volume average particle size and is measured according to JIS Z 8819-2.

The filler content in the back layer is preferably 1% by mass or more and 10% by mass or less, more preferably 3% by mass or more and 7% by mass or less. As a result, the head residue prevention property and anti-blocking property of the thermal transfer sheet of the present invention can be further improved.

In one embodiment, the back layer comprises a resin material, such as cellulose resin, styrene resin, vinyl resin, polyester, polyurethane, (meth)acrylic resin and modified resins thereof. Among these, (meth)acrylic resins and silicone-modified (meth)acrylic resins are preferred, and silicone-modified (meth)acrylic resins are more preferred, for the reasons of head residue prevention and blocking resistance.

The content of the resin material in the back layer is preferably 80% by mass or more and 99% by mass or less, more preferably 85% by mass or more and 95% by mass or less. As a result, the head residue prevention property and anti-blocking property of the thermal transfer sheet of the present invention can be further improved.

The back layer can contain the above-described additives as long as the characteristics of the present invention are not impaired.

The thickness of the back layer is preferably 0.03 μm or more and 1 μm or less, more preferably 0.05 μm or more and 0.6 μm or less. As a result, the head residue prevention property and anti-blocking property of the thermal transfer sheet of the present invention can be further improved.

In the thermal transfer sheet of the present invention, the ratio of the average particle size of the filler contained in the back layer to the thickness of the back layer (average particle size of the filler/thickness of the back layer) is 0.8 or more and 3.5 or less. It is preferably 1 or more and 3 or less. As a result, the head residue prevention property and anti-blocking property of the thermal transfer sheet of the present invention can be remarkably improved.

The back layer is formed by dispersing or dissolving the above material in water or an appropriate solvent, and coating the material by known means such as roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating and rod coating. , to form a coating film by applying it on a substrate, and drying it.

(Release layer)
In one embodiment, the transfer layer included in the thermal transfer sheet of the present invention includes a release layer below the colored layer. Thereby, the high-speed transfer aptitude of the thermal transfer sheet of the present invention can be further improved.

In one embodiment, the release layer contains wax as a major component. Examples of waxes include natural waxes such as beeswax, spermaceti, Japan wax, rice bran wax, carnauba wax, candelilla wax and montan wax, paraffin wax, microcrystalline wax, oxidized wax, ozokerite, ceresin, ester wax and polyethylene wax. synthetic waxes, higher saturated fatty acids such as margaric acid, lauric acid, myristic acid, palmitic acid, stearic acid, furoic acid and behenic acid, higher saturated monohydric alcohols such as stearyl alcohol and behenyl alcohol, higher esters such as fatty acid esters of sorbitan , higher fatty acid amides such as stearic acid amide and oleic acid amide.
Among these, carnauba wax and paraffin wax are preferable from the viewpoint of high-speed transfer suitability.
In addition, the release layer can contain two or more kinds of waxes.

The wax content in the release layer is preferably 70% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 98% by mass or less. Thereby, the high-speed transfer aptitude of the thermal transfer sheet of the present invention can be further improved.

Also, in one embodiment, the release layer contains a resin material as a main component. By including a resin material as a main component in the release layer, the abrasion resistance of the printed matter can be further improved. Examples of resin materials include (meth)acrylic resins, cellulose resins, vinyl resins, polyurethanes, silicone resins, and fluorine resins.

The content of the resin material in the release layer is preferably 70% by mass or more and 99% by mass or less, more preferably 80% by mass or more and 98% by mass or less. Thereby, the high-speed transfer aptitude and abrasion resistance of the thermal transfer sheet of the present invention can be further improved.

The thickness of the release layer is preferably 0.1 μm or more and 3 μm or less, more preferably 0.2 μm or more and 2 μm or less. Thereby, the high-speed transfer aptitude and abrasion resistance of the thermal transfer sheet of the present invention can be further improved.

The release layer can be formed by dispersing or dissolving the above material in water or an appropriate solvent, followed by known methods such as roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating and rod coating. It can be formed by applying it on a base material or the like by means to form a coating film, and drying it.

(release layer)
In one embodiment, the thermal transfer sheet of the present invention comprises a release layer between the substrate and the transfer layer. Thereby, the high-speed transfer aptitude of the thermal transfer sheet of the present invention can be further improved.

In one embodiment, the release layer comprises a resin material, such as (meth)acrylic resins, polyurethanes, acetal resins, polyamides, polyesters, melamine resins, polyol resins, cellulose resins and silicone resins.

In one embodiment, the release layer contains a release material such as silicone oil, phosphate ester plasticizer, fluorine compound, wax, metal soap and filler.

The thickness of the release layer is not particularly limited, and can be, for example, 0.2 μm or more and 2 μm or less.

The release layer is formed by dispersing or dissolving the above material in water or an appropriate solvent, and applying known means such as roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating and rod coating. It can be formed by coating on a base material or the like to form a coating film and drying it.

(primer layer)
In one embodiment, the thermal transfer sheet of the present invention comprises a primer layer between any layers. This can improve the adhesion between adjacent layers.

In one embodiment, the primer layer comprises resinous materials such as polyesters, vinyl resins, polyurethanes, (meth)acrylic resins, polyamides, polyethers, styrene resins and cellulose resins.

The thickness of the primer layer is not particularly limited, and can be, for example, 0.2 μm or more and 2 μm or less.

The primer layer is formed by dispersing or dissolving the above materials in water or an appropriate solvent, and applying the coating by known means such as roll coating, reverse roll coating, gravure coating, reverse gravure coating, bar coating and rod coating. , to form a coating film by applying it on a substrate, and drying it.

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1
A PET film having a thickness of 4.5 μm was prepared, and a release layer forming coating liquid having the following composition was applied to one surface of the PET film and dried to form a release layer having a thickness of 0.5 μm.
<Coating solution for forming release layer>
・ Carnauba wax 50 parts by mass (manufactured by Konishi Co., Ltd.)
・ Paraffin wax 50 parts by mass (manufactured by Konishi Co., Ltd.)
・Water 100 parts by mass ・Isopropanol (IPA) 100 parts by mass

A colored layer-forming coating liquid having the following composition was applied onto the release layer formed as described above and dried to form a colored layer having a thickness of 1 μm.
<Coating liquid for forming colored layer>
・Carbon black 40 parts by mass ・Ethylene-vinyl acetate copolymer 20 parts by mass (Mitsui DuPont Chemical Co., Ltd., Evaflex (registered trademark) EV 220ETR, MFR 150 g / 10 min., melting point 71 ° C., vinyl acetate composition ratio 28 mass %)
- Terpene resin 20 parts by mass (manufactured by Yasuhara Chemical Co., Ltd., Polystar (registered trademark) T100, terpene phenol resin, softening point 100 ± 5 ° C.)
・ Polyolefin 20 parts by mass (manufactured by Nippon Paper Industries Co., Ltd., Auroren (registered trademark) 100S, melting point 75 to 85 ° C.)
・Methyl ethyl ketone (MEK) 100 parts by mass ・Toluene 100 parts by mass

On the other side of the PET film, a coating solution for forming a back layer having the following composition was applied and dried to form a back layer having a thickness of 0.1 μm to obtain a thermal transfer sheet.
<Coating solution for forming back layer>
・ Silicone modified (meth) acrylic resin 9.5 parts by mass (manufactured by Natoco Co., Ltd., Polyalloy (registered trademark) NSA-X55)
・ Filler 0.5 parts by mass (manufactured by Nippon Shokubai Co., Ltd., Eposter (registered trademark) SS, average particle size 0.1 μm)
・MEK 20 parts by mass ・Toluene 20 parts by mass

Examples 2-25 and Comparative Examples 1-7
Example 1 except that at least one of the thickness of the substrate, the thickness of the release layer, the configuration and thickness of the colored layer, and the configuration and thickness of the back layer was changed to the values shown in Tables 1 and 2. A thermal transfer sheet was prepared in the same manner as above.
Details of each component in Tables 1 and 2 are as follows, and MFR units are omitted in the tables.
<Colored layer>
(ethylene-vinyl acetate copolymer)
Evaflex (registered trademark) EV210ETR: manufactured by Mitsui DuPont Chemical Co., Ltd., MFR 400 g/10 min. , melting point 73 ° C., vinyl acetate composition ratio 28% by mass
Evaflex (registered trademark) EV205WR: manufactured by Mitsui DuPont Chemical Co., Ltd., MFR 800 g/10 min. , melting point 73 ° C., vinyl acetate composition ratio 28% by mass
(terpene resin)
・ Polystar (registered trademark) T130: manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 130 ± 5 ° C.
Polystar (registered trademark) T80: manufactured by Yasuhara Chemical Co., Ltd., terpene phenol resin, softening point 80 ± 5 ° C.
・ YS resin TO105: manufactured by Yasuhara Chemical Co., Ltd., softening point 105 ± 5 ° C.
・YS Resin PX1000: manufactured by Yasuhara Chemical Co., Ltd., softening point 100±5° C.
(polyolefin)
・ Auroren (registered trademark) 150S: manufactured by Nippon Paper Industries Co., Ltd., melting point 105 to 135 ° C.
・ Auroren (registered trademark) 200S: manufactured by Nippon Paper Industries Co., Ltd., melting point 60 to 70 ° C.
・ Auroren (registered trademark) 350S: manufactured by Nippon Paper Industries Co., Ltd., melting point 65 to 75 ° C.
・Ceramer 1608: manufactured by Toyo Adol Co., Ltd., melting point 78°C
<Back layer>
(Silicone modified (meth)acrylic resin)
・Polyalloy (registered trademark) SX-082: manufactured by Natoco Co., Ltd. ・Polyalloy (registered trademark) NSA-B20: manufactured by Natoco Co., Ltd. (filler)
・ Eposter (registered trademark) S, manufactured by Nippon Shokubai Co., Ltd., average particle size 0.2 μm
・ Eposter (registered trademark) S6, manufactured by Nippon Shokubai Co., Ltd., average particle size 0.4 μm
・ Eposter (registered trademark) S12, manufactured by Nippon Shokubai Co., Ltd., average particle size 1.2 μm

Comparative example 7
A thermal transfer sheet was produced in the same manner as in Example 1, except that the composition of the coating solution for forming the back layer was changed as follows and the thickness of the back layer was changed to 0.2 μm.
<Coating solution for forming back layer>
・Styrene-acrylonitrile copolymer 11 parts by mass ・Linear saturated polyester 0.3 parts by mass ・Zinc stearyl phosphate 6 parts by mass ・Melamine resin particles (average particle diameter 0.4 μm) 3 parts by mass ・MEK 80 parts by mass

<<High-speed transfer aptitude evaluation-1>>
Using the thermal transfer sheets obtained in the above Examples and Comparative Examples and a printer (SDX60, manufactured by Markem Image Co., Ltd.) equipped with an end-face type thermal head with a resolution of 300 dpi, a laminate of a PET film and an LLDPE film, which are transfer materials (manufactured by Dai Nippon Printing Co., Ltd., hereinafter referred to as transfer material 1) was printed on the surface of a PET film at a printing density of 130% and a printing speed of 40 m/min. A 2-dot character pattern image and a barcode image were formed under the conditions of , and a print 1 was obtained.
Similarly, an image was formed on the surface of the stretched PP film of the laminate of the stretched PP film and the non-axially stretched PP film (hereinafter referred to as the stretched PP film 2) to obtain a print 2.
The images formed on the above two transfer-receiving materials were visually observed and evaluated according to the following evaluation criteria. The evaluation results are summarized in Tables 1-3.
(Evaluation criteria)
A: It was confirmed that a good image was formed without omission or fading in both prints 1 and 2.
B: It was confirmed that a good image was formed on either one of the printed matter 1 or 2 without missing or blurring. omission and fading were observed.
NG: In both Prints 1 and 2, voids and blurring to the extent of practical problems were observed.

<<High-speed transfer aptitude evaluation-2>>
A printing speed of 50 m/min. An image was formed and evaluated in the same manner as above, except that it was changed to . The evaluation results are summarized in Tables 1-3.

<<Evaluation of suitability for high-speed transfer-3>>
A printing speed of 60 m/min. An image was formed and evaluated in the same manner as above, except that it was changed to . The evaluation results are summarized in Tables 1-3.

<<Head scum prevention property evaluation>>
Using the thermal transfer sheets obtained in the above Examples and Comparative Examples and a printer (Markem Image, SDX60) equipped with an end-face thermal head with a resolution of 300 dpi, a print density of 130 was printed on the PET film surface of the transfer material 1. %, printing speed 40 m/min. A 3-dot character pattern image was formed under the conditions of , and 1,000 prints were produced.
Next, a tape (Scotch (registered trademark) tape (BK-24) manufactured by 3M) was attached to the thermal head, left to stand for 1 minute, and then peeled off. Images formed on the peeled tape and printed matter were visually observed and evaluated based on the following evaluation criteria. The evaluation results are summarized in Tables 1-3.
(Evaluation criteria)
A: Adhesion of head scum was hardly observed.
B: Adhesion of head scum was observed a little, but the formed image was neither missing nor blurred, and there was no problem in practical use.
NG: Adhesion of head scum was often observed, and voids and blurring of the formed image were observed.

<<Adhesion Evaluation>>
A tape (Scotch (registered trademark) tape (BK-24) manufactured by 3M) was placed on the barcode image of printed matter 1 prepared in high-speed transfer suitability test-1 in an environment of 25° C. and relative humidity of 60%. A pressure of 200 g was evenly applied once using a rubbing tester (manufactured by Suga Test Instruments Co., Ltd.) for adhesion. After standing in that state for 10 minutes, the tape was peeled off. The bar code image after peeling was visually observed and evaluated based on the following evaluation criteria. The evaluation results are summarized in Tables 1-3.
(Evaluation criteria)
A: No change was observed in the image before and after the tape was peeled off.
B: Part of the image was chipped due to peeling of the tape, but there was no practical problem.
NG: Due to peeling of the tape, a large defect was observed in the image, and the judgment result by a bar code checker (Quick Check 850 manufactured by Honeywell) was E, F, or judgment impossible, which was a practical problem.

<<Blocking resistance evaluation>>
Two thermal transfer sheets obtained in the above Examples and Comparative Examples were superimposed so that the colored layer and the back layer faced each other, and a pressure of 0.196 MPa was applied, and the sheet was left still for 24 hours at 45° C. and a relative humidity of 85%. placed. After standing still, the colored layer and the back layer were peeled off and evaluated based on the following evaluation criteria. The evaluation results are summarized in Tables 1-3.
(Evaluation criteria)
A: The colored layer and the back layer can be easily peeled off.
B: Slight sticking between the colored layer and the back layer occurs, but there is no practical problem.
NG: Sticking between the colored layer and the back layer occurs, which poses a practical problem.

<<Scratch resistance evaluation>>
The bar code image of printed matter 1 prepared in high-speed transfer suitability test-1 was rubbed with corrugated cardboard under a load of 500 g using a friction resistance tester (manufactured by Suga Test Instruments Co., Ltd.). The state of the bar code image after 50 reciprocating rubbings and 100 reciprocating rubbings was visually observed and evaluated based on the following evaluation criteria. The evaluation results are summarized in Tables 1-3.
(Evaluation criteria)
A: No defects were observed in the bar code image even after 100 reciprocating rubbings.
B: No chipping was observed in the barcode image after 50 reciprocating rubbings, but chipping was observed in the barcode image after 100 reciprocating rubbings.
C: Defects were observed in the bar code image after 50 reciprocating rubbings.

10: Thermal transfer sheet, 11: Colored layer, 12: Transfer layer, 13: Base material, 14: Back layer, 15: Release layer

Claims (9)

A transfer layer having a colored layer, a substrate, and a back layer,
The colored layer contains an ethylene-vinyl acetate copolymer, a terpene resin, a polyolefin, and a coloring agent, and the content of the ethylene-vinyl acetate copolymer in the colored layer is 5% by mass or more and 30% by mass or less. ,
The back layer contains a filler,
A thermal transfer sheet, wherein the ratio of the average particle size of the filler to the thickness of the back layer (average particle size of filler/thickness of back layer) is 0.8 or more and 3.5 or less. 2. The thermal transfer sheet according to claim 1, wherein the filler has an average particle size of 0.05 [mu]m or more and 1.5 [mu]m or less. 3. The thermal transfer sheet according to claim 1, wherein the content of said filler in said back layer is 1% by mass or more and 10% by mass or less. The thermal transfer sheet according to any one of claims 1 to 3, wherein the back layer has a thickness of 0.03 µm or more and 1 µm or less. The thermal transfer sheet according to any one of claims 1 to 4, wherein the back layer contains at least one of a (meth)acrylic resin and a silicone-modified (meth)acrylic resin. The melt flow rate of the ethylene-vinyl acetate copolymer is 100 g/10 min. Above 1000g/10min. The thermal transfer sheet according to any one of claims 1 to 5, wherein: The thermal transfer sheet according to any one of claims 1 to 6, wherein the terpene resin has a softening point of 70°C or higher and 140°C or lower. The thermal transfer sheet according to any one of claims 1 to 7, wherein the polyolefin has a melting point of 50°C or higher and 140°C or lower. The thermal transfer sheet according to any one of claims 1 to 8, wherein the transfer layer has a thickness of 0.5 µm or more and 2.5 µm or less.

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