JP2987534B2 - Thermal transfer recording sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer recording sheet used for a thermal transfer ribbon used in a thermal transfer type hard code printer, and more particularly, to a backing layer which does not contain a heat-meltable ink and which directly contacts a thermal head. About.

[0002]

2. Description of the Related Art In recent years, as a method of recording information created by a computer, a word processor, or the like, a recording method by a thermal transfer method in which ink is melted by the heat of a thermal head is (1) low cost, (2)
(3) there is no danger of information being recorded like thermal recording paper being erased due to changes in the surrounding environment;
(4) It is rapidly becoming popular because it can be easily stored after printing. Accordingly, higher performance of the heat-sensitive transfer film such as higher printing speed and higher sensitivity is required.

[0003] For this purpose, the surface of the base sheet made of polyester or the like opposite to the heat-fusible ink layer, that is, the layer (back layer) that directly contacts the thermal head.
There has been a demand for higher performance, and much research has been conducted on it. As a typical example, Japanese Patent Application Laid-Open No.
In addition to the method of depositing a metal such as aluminum as disclosed in JP-A-143152, there is a method of providing a heat-resistant resin layer such as a silicone resin or an epoxy resin as disclosed in JP-A-55-7467. As means for improving the lubricity in order to cope with high-speed printing, as disclosed in JP-A-56-155794, a highly lubricious inorganic pigment such as talc, mica and silica is used. A method of incorporating the compound into a resin having
As disclosed in Japanese Patent Application Laid-Open No. 9-259, a method in which a resin contains a surfactant such as sodium stearate or polyoxyethylene stearate, and a method disclosed in JP-A-60-259495.
As disclosed in Japanese Patent Application Laid-Open No. H10-260, there is a method of improving heat resistance by crosslinking an acrylic polymer with a crosslinking agent such as a polyvalent isocyanate or an epoxy resin.

[0004]

However, Japanese Patent Application Laid-Open No.
The method of depositing a metal such as aluminum as disclosed in JP-A-143152 is too expensive for the deposition equipment, and it is difficult to sufficiently increase the printing sensitivity because the film thickness cannot be reduced. The method of providing a heat-resistant resin layer such as silicone disclosed in Japanese Patent No. 7467 has a problem that it is difficult to have sufficient activity for heat transfer printing and heat resistance. Further, in the method of incorporating an inorganic lubricating pigment such as talc into a resin as disclosed in JP-A-56-155794, the lubricity may certainly be improved, but the hardness of the inorganic substance is extremely high. However, as many prints are made, the thermal head which plays an important role in printing may be significantly damaged. In the method disclosed in JP-A-57-129789, in which a surfactant such as sodium stearate is contained in a resin, although the lubricity is improved, the surfactant is transferred to the ink surface during storage and the printed image May be affected, and JP-A-60-259495
In the method of improving the heat resistance of an acrylic polymer as shown in Japanese Patent Publication No. JP-A-2002-15095 with a cross-linking agent such as isocyanate, aging by heat is necessary, and there is a risk of causing wrinkles to the base material, Is that there is little certainty about the progress of the process.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a thermal transfer recording sheet having both lubricity and heat resistance that can sufficiently withstand high-speed printing at low cost.

[0006]

As a result of extensive studies, the present inventor has found that an electron beam or ultraviolet curable resin of silicon-modified epoxy acrylate, or a silicon-modified epoxy is provided on the surface of the base sheet opposite to the hot-melt ink layer. The present inventors have found that a heat-sensitive transfer recording sheet having a back layer formed of an electron beam or an ultraviolet curable resin of urethane acrylate is suitable for the above object, and have completed the present invention.

That is, according to the present invention, there is provided a heat-sensitive transfer recording sheet comprising a heat-fusible ink layer provided on one side of a base sheet and a back layer provided on the other side of the base sheet. Wherein the thermal transfer recording sheet comprises at least one of the following cured resins. (A) A photopolymerizable prepolymer having active acryloyl groups added to both ends of a silicon-modified epoxy resin,
A silicon-modified epoxy acrylate electron beam curing resin cured by irradiating an electron beam of 0 to 5000 eV. (B) A silicon-modified epoxy resin cured by irradiating a photopolymerizable prepolymer having active acryloyl groups added to both ends of the silicon-modified epoxy resin and a photoinitiator or a photosensitizer with ultraviolet rays of 200 to 400 nm. Acrylate UV curable resin. (C) A photopolymerizable prepolymer obtained by adding active acryloyl groups to both ends of a silicon-modified urethane resin,
A silicon-modified urethane acrylate electron beam curable resin cured by irradiating an electron beam of 0 to 5000 eV. (D) A silicon-modified epoxy cured by irradiating a photopolymerizable prepolymer in which active acryloyl groups are added to both ends of a silicon-modified urethane resin and a photoinitiator or a photosensitizer with ultraviolet rays of 200 to 400 nm. Acrylate UV curable resin.

In the thermal transfer recording sheet of the present invention, the back layer made of the above-mentioned cured resin is provided on the surface of the base sheet opposite to the heat-meltable ink layer, so that the heat received from the thermal head during printing can be reduced. It has both heat resistance that can withstand and good lubrication that is indispensable for high-speed printing.

Hereinafter, the present invention will be described in more detail. The invention according to claim 1 is a silicon-modified epoxy acrylate electron beam cured by irradiating an electron beam of 250 to 5000 eV to a photopolymerizable prepolymer in which active acryloyl groups are added to both ends of a silicon-modified epoxy resin. A back layer made of a cured resin is provided on the surface of the base sheet opposite to the heat-fusible ink layer.

The photopolymerizable prepolymer used in the present invention is obtained by adding active acryloyl groups to both ends of a silicon-modified epoxy resin and has the properties of a silicon-modified epoxy resin, and has hardness and flexibility. Combine,
Excellent curability. Silicon-modified epoxy acrylate is generated by esterifying an epoxy group of an epoxy oligomer with acrylic acid.

In the present invention, the above prepolymer is applied to the surface of the base sheet opposite to the hot-melt ink layer, and the applied surface is irradiated with an electron beam of 250 to 5000 eV to cure the silicon-modified epoxy acrylate. A back layer made of resin is formed. As a method of applying the prepolymer, since no solvent is used, an offset gravure coat or a multi-stage roll coat is preferable in order to obtain a uniform application state. In addition, in the present invention, an electron beam irradiating device is required as a minimum, so that a large-scale drying device is not required. In addition, since no solvent is used, no equipment is required for the recovery of the scattered components of the organic solvent, which is a problem in the normal heat drying process, and the energy required for coating requires heat drying. There is an advantage that about 3% of the cost is reduced.

In the formation of the back layer, the amount of adhesion is preferably 0.45 to ensure sufficient heat resistance without deteriorating sensitivity.
g / m ² to 0.10 g / m ² is preferable, and since the hardening of the coated surface is completed in 1 to 5 seconds, the coating speed can be increased to 150 m / min. is there. The electron beam irradiation equipment used here is 25
No special conditions are required as long as light having a wavelength of 0 to 5000 eV can be emitted.

According to a second aspect of the present invention, there is provided a photopolymerizable prepolymer in which active acryloyl groups are added to both ends of a silicon-modified epoxy resin and a photoinitiator or photosensitizer.
A back layer made of a silicon-modified epoxy acrylate ultraviolet curable resin cured by irradiating ultraviolet rays of 00 to 400 nm is provided on the surface of the base sheet opposite to the heat-meltable ink layer.

The photopolymerizable prepolymer used here is obtained by adding active acryloyl groups to both ends of a silicon-modified epoxy resin, and is the same as that used in the invention of claim 1. It is. In this method, the prepolymer and the photoinitiator or photosensitizer are applied to the surface of the base sheet opposite to the heat-meltable ink layer, and the applied surface is irradiated with ultraviolet rays of 200 to 400 nm. By
A back layer made of a silicone-modified epoxy acrylate cured resin is formed.

The photoinitiator or photosensitizer as referred to in the present invention is activated immediately upon irradiation with ultraviolet rays of 200 to 400 nm, and reacts with an acrylate group located at the terminal end of the photopolymerizable prepolymer by a curing reaction. Specifically, biacetyl, acetophenone,
Examples include benzophenone, Michler's ketone, benzyl, benzoin, benzoisobutyl ether, benzylmethyl ketal, tetramethylthiuram sulfide, azobisisobutylnitrile, benzoyl peroxide and the like.

As a method for applying the above-mentioned prepolymer and photoinitiator or photosensitizer, no solvent is used at all, as in the case of the first aspect of the present invention. Coats and multi-stage roll coats are preferred. Further, in the present invention, it is sufficient that the ultraviolet irradiation device is the minimum required, and a large-scale drying device is not required. In addition, since no solvent is used, no equipment is required to recover the scattered components of the organic solvent, which is a problem during the normal heat drying process.The energy required for coating requires heat drying. There is an advantage that about one tenth of the above is required.

In the formation of the back layer, the amount of adhesion is preferably 0.45 to ensure sufficient heat resistance without deteriorating the sensitivity.
g / m ² to 0.10 g / m ² is preferable, and since the hardening of the coated surface is completed in 3 to 10 seconds, the coating speed can be increased to 150 m / min. is there. The ultraviolet irradiation equipment used here is 2
No special conditions are required as long as light having a wavelength of 50 to 400 nm can be emitted.

According to a third aspect of the present invention, there is provided a silicon-modified urethane cured by irradiating an electron beam of 250 to 5000 eV to a photopolymerizable prepolymer having an active acryloyl group added to both ends of the silicon-modified urethane resin. A back layer made of an acrylate electron beam curable resin is provided on the surface of the base sheet opposite to the hot-melt ink layer.

The photopolymerizable prepolymer used here is obtained by adding an active acryloyl group to both ends of a silicon-modified urethane resin, and has excellent flexibility and curability unique to urethane. The silicon-modified urethane acrylate is generated by reacting an acrylate having a hydroxy bond (—OH) with an isocyanate group (—NCO) when a urethane bond (—NHCO) is generated.

The method of applying the prepolymer, its conditions, advantages and the like can be said to be the same as those of the first aspect of the present invention.

According to a fourth aspect of the present invention, a photopolymerizable prepolymer having an active acryloyl group added to both ends of a silicon-modified urethane resin and a photoinitiator or photosensitizer are used.
A back layer made of a silicon-modified urethane acrylate ultraviolet-curable resin cured by irradiating ultraviolet rays having a wavelength of 00 to 400 nm is provided on a side of the base sheet opposite to the hot-melt ink layer.

The photopolymerizable prepolymer used here is obtained by adding an active acryloyl group to both ends of a silicon-modified urethane resin, and is the same as that used in the invention of claim 3. It is. In this method, the prepolymer and the photoinitiator or photosensitizer are applied to the surface of the base sheet opposite to the heat-meltable ink layer, and the applied surface is irradiated with ultraviolet rays of 200 to 400 nm. By
A back layer made of a silicone-modified urethane acrylate cured resin is formed.

The above photoinitiator and photosensitizer are described in claim 2
The same ones as those used in the invention of the invention are used, and the method of applying the prepolymer and the photoinitiator or the photosensitizer, its conditions, advantages and the like are the same as those of the invention of the second aspect. I can say that.

In the present invention, as the substrate sheet (substrate film), a conventionally known substrate film is used as it is, as long as it has heat resistance and strength enough to withstand continuous printing, and it is particularly limited. Not something. For example, 0.40
Polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol having a thickness of about 0.6 μm, inexpensive and having a constant production capacity Plastic films such as polyethylene terephthalate and polyethylene naphthalate, and paper such as condenser paper and paraffin paper are used.

In the present invention, a conventionally known heat-fusible ink layer is used as it is as the heat-fusible ink layer, and is not particularly limited. That is, the heat-fusible ink layer used in the present invention is composed of a heat-fusible substance, a thermoplastic substance, a colorant, an oil or the like, and is formed by appropriately formulating and dispersing and applying these substances.

In this case, specific examples of the heat-fusible substance include waxes such as paraffin wax, carnauba wax, microcrystalline wax, beeswax, selenium wax, low molecular weight polyethylene, low molecular weight polystyrene, and low molecular weight polyamide. Rosin, petroleum resin, terpene resin and the like. Specific examples of the thermoplastic substance include methyl cellulose, hydroxyethyl cellulose, cellulose resin containing a functional group such as carboxymethyl cellulose, polyvinylpyrrolidone, polyvinyl alcohol, vinyl acetate resin, vinyl chloride resin, vinylidene chloride resin and the like. Examples include vinyl resins, polyacrylamide, gelatin, acrylic resins, methacrylic resins, and the like.

As the colorant, inorganic and organic dyes or pigments used in printing inks, dyes and the like can be used, and the color of the colorant is not limited. Specific examples thereof include direct dyes such as carbon black, red iron red, disazo yellow, Priliant Carmine 6B, Lake Red C, Fast Sky Blue, and Phthalocyanine Green, oily dyes, and basic dyes.

In the present invention, if necessary, an intermediate layer for improving adhesion to the substrate, a mat layer for matting, and an ink between the hot-melt ink layer and the substrate sheet. It is also possible to provide a release layer or the like for assisting the transfer of the layer, or to provide an over layer on the hot-melt ink layer in order to improve thermal sensitivity or fixability.

[0029]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited thereto. The percentages and parts shown below are all based on weight.

Example 1 [Solution A] 5 parts of silicon-modified epoxy acrylate (photopolymerizable prepolymer) First, [Solution A] was applied using a gravure coater so that the adhesion amount was about 0.50 g / m ² . The composition was applied on a polyester film having a thickness of 0.45 μm, and irradiated with an electron beam using an electron beam irradiation apparatus having a main wavelength of 500 eV for 2 seconds to cure the applied product, thereby forming a back layer of the thermal transfer sheet.

Next, a mixture having the following composition was dispersed at 110 ° C. for 8 hours using a sand mill to prepare [Solution B]. [B liquid] Paraffin wax 60 parts Carnauba wax 20 parts Carbon black 15 parts Ethylene / vinyl acetate copolymer resin 5 parts

Subsequently, [A] of the polyester film
[Liquid] was applied to the surface not coated with [Liquid] using a hot melt gravure coater so that the coating amount was 4.0 g / m ² , and a heat-meltable ink layer was formed. Created.

After cutting this thermal transfer film into a printable form, a personal word processor NL manufactured by Ricoh Co., Ltd.
At -1, printing was performed using high-quality paper and evaluated. Even if the printing level of the thermal head was adjusted from the lowest level to the highest level at any time, the printing state and running state did not become abnormal, and the sensitivity was extremely high and It was found to have high heat resistance. Table 1 shows the results.

Example 2 A thermal transfer film was prepared in the same manner as in Example 1 except that the [A liquid] applied to the polyester film was cured for 1 second by an electron beam curing device having a main wavelength of 1000 eV. Was prepared, and printing evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 1 The procedure of Example 1 was repeated except that the [solution A] coated on the polyester film was irradiated with an electron beam of 500 eV.
A heat transfer film was prepared in the same manner as in Example 1 except that the infrared ray of 00 nm was irradiated, and printing evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 [solution A] applied on a polyester film
Except that electron beam irradiation was not performed, a thermal transfer film was prepared in the same manner as in Example 1, and printing evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Example 3 [Solution C] Silicon-modified epoxy acrylate 5 parts (photopolymerizable prepolymer) Benzyldimethyl ketal 0.5 part (photoinitiator)

First, the [liquid C] was coated with a gravure coater to a thickness of about 0.50 g / m ² so as to have an adhesion amount of about 0.50 g / m ² .
Apply 45 μm on a polyester film, and irradiate 8
The coating was cured for 2 seconds to form a back layer of the thermal transfer sheet.

Next, the polyester film [C
[Liquid B] was applied to the surface not coated with [Liquid] in the same manner as in Example 1 to form a heat-meltable ink layer, thereby producing a thermal transfer film.

When the printing evaluation of this transfer film was performed in the same manner as in Example 1, even if the printing level of the thermal head was adjusted from the lowest level to the highest level at any time, abnormalities occurred in the printing state and running state. It was found to have extremely high sensitivity and high heat resistance. Table 1 shows the results.

Example 4 [Solution D] Silicon-modified epoxy acrylate 5 parts (photopolymerizable prepolymer) Benzophenone 0.5 part (photoinitiator)

A thermal transfer film was prepared in the same manner as in Example 3 except that [Liquid C] was changed to [Liquid D] in Example 3, and printing evaluation was performed in the same manner as in Example 3. . Table 1 shows the results.

Comparative Example 3 A thermal transfer film was prepared in the same manner as in Example 3 except that [Liquid C] was changed to [Liquid A].
Printing evaluation was performed in the same manner as in Example 3. Table 1 shows the results.

Comparative Example 4 A thermal transfer film was produced in the same manner as in Example 3 except that the UV light was not applied to the [liquid C] applied on the polyester film. Print evaluation was performed. Table 1 shows the results.

Example 5 [Solution E] Silicon-modified urethane acrylate 5 parts (photopolymerizable prepolymer) In the same manner as in Example 1, except that [Solution A] was replaced with [Solution E]. To produce a thermal transfer film.

When the printing evaluation was performed on this transfer film in the same manner as in Example 1, even if the printing level of the thermal head was adjusted from the lowest level to the highest level at any time, abnormalities were observed in the printing state and running state. It was found to have extremely high sensitivity and high heat resistance. Table 1 shows the results.

Example 6 In Example 5, the [E solution] applied to the polyester film was irradiated with an electron beam at a main wavelength of 1000 eV.
A thermal transfer film was prepared in the same manner as in Example 5, except that the electron beam was irradiated with the electron beam irradiation apparatus of Example 5, and printing evaluation was performed in the same manner as in Example 5. Table 1 shows the results.
Shown in

Comparative Example 5 Instead of irradiating the [solution E] applied on the polyester film in Example 5 with an electron beam of 500 eV,
A thermal transfer film was prepared in the same manner as in Example 5, except that the infrared ray of 700 nm was irradiated, and printing evaluation was performed in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 6 [E liquid] applied on a polyester film
Except that electron beam irradiation was not performed, a thermal transfer film was prepared in the same manner as in Example 5, and printing evaluation was performed in the same manner as in Example 5. Table 1 shows the results.

Example 7 [Solution F] Silicon-modified urethane acrylate 5 parts (photopolymerizable prepolymer) Benzyldimethyl ketal 0.5 part (photoinitiator)

A thermal transfer film was prepared in the same manner as in Example 3, except that [Solution C] was changed to [Solution F].

When the printing evaluation of this transfer film was performed in the same manner as in Example 3, even if the printing level of the thermal head was adjusted from the lowest level to the highest level as needed, abnormalities were found in the printing state and running state. It was found to have extremely high sensitivity and high heat resistance. Table 1 shows the results.

Example 8 [Solution G] Silicon-modified urethane acrylate 5 parts (photopolymerizable prepolymer) Benzophenone 0.5 part (photoinitiator)

A heat transfer film was prepared in the same manner as in Example 7 except that [Solution F] was replaced with [Solution G], and printing evaluation was performed in the same manner as in Example 7. . Table 1 shows the results.

Comparative Example 7 A thermal transfer film was prepared in the same manner as in Example 7, except that [Solution F] was changed to [Solution E].
Printing evaluation was performed in the same manner as in Example 7. Table 1 shows the results.

Comparative Example 8 A thermal transfer film was produced in the same manner as in Example 7 except that the [F solution] applied to the polyester film was not irradiated with an electron beam. The printing was evaluated. Table 1 shows the results.

[0057]

[Table 1] Note) Heat resistance: Heat resistance at the maximum concentration. Runnability: The runnability of the film before and after printing during 50 m printing. Printability: Print quality before and after printing during 50 m printing. 〇: good △: slightly poor ×: bad

As is evident from Table 1, all of the thermal transfer films of Examples 1 to 8 have excellent heat resistance and sufficient lubricity, and can form excellent images in high-speed printing. On the other hand, the thermal transfer films of Comparative Examples 1 to 2 and 5 to 6 did not undergo electron beam irradiation and thus were not sufficiently cured, sticking occurred, and Comparative Examples 3 and 7
The thermal transfer films of Nos. 1 and 2 did not contain a photoinitiator, and the thermal transfer films of Comparative Examples 4 and 8 were not irradiated with ultraviolet rays.

[0059]

According to the thermal transfer recording sheet of the present invention, since the back layer having the above-described structure is provided on the surface of the base sheet opposite to the surface of the heat-meltable ink layer, the heat-meltable ink may be applied to the ink layer. However, the use of the compound has excellent heat resistance and sufficient lubricity, and can produce excellent images even in high-speed printing.

Further, the thermal transfer recording sheet of the present invention requires less energy as compared with a sheet which is crosslinked by heat such as polyvalent isocyanate because the back layer is formed by an electron beam irradiation apparatus or an ultraviolet irradiation apparatus. There is also an advantage that curing proceeds reliably in a short time.

Claims (4)

(57) [Claims] 1. A heat-sensitive transfer recording sheet comprising a heat-fusible ink layer provided on one surface of a substrate sheet and a back layer provided on the other surface of the substrate sheet, wherein the back layer is made of a silicon-modified epoxy resin. Of the photopolymerizable prepolymer having active acryloyl groups added to both ends of
A heat-sensitive transfer recording sheet comprising a silicon-modified epoxy acrylate electron beam curable resin cured by irradiation with an electron beam of 0 eV. 2. The method according to claim 1, wherein the back layer comprises a photopolymerizable prepolymer in which active acryloyl groups are added to both ends of a silicon-modified epoxy resin and a photoinitiator or photosensitizer.
2. The heat-sensitive transfer recording sheet according to claim 1, wherein the heat-sensitive transfer recording sheet is made of a silicon-modified epoxy acrylate ultraviolet-curable resin cured by irradiating ultraviolet light having a wavelength of about 400 nm. 3. A silicon-modified urethane acrylate in which the back layer is cured by irradiating an electron beam of 250 to 5000 eV to a photopolymerizable prepolymer obtained by adding active acryloyl groups to both ends of a silicon-modified urethane resin. 2. The heat-sensitive transfer recording sheet according to claim 1, comprising an electron beam-curable resin. 4. The method according to claim 1, wherein the back layer comprises a photopolymerizable prepolymer obtained by adding active acryloyl groups to both ends of a silicon-modified urethane resin and a photoinitiator or photosensitizer.
2. The heat-sensitive transfer recording sheet according to claim 1, wherein the heat-sensitive transfer recording sheet is made of a silicon-modified urethane acrylate ultraviolet-curable resin cured by irradiating ultraviolet light having a wavelength of 400 nm.