JP3055811B2 - Thermal transfer sheet and manufacturing method thereof - 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 sheet and a method for producing the same, and more particularly, to a novel OHP in which a thermal transfer sheet and a transparent resin film for OHP are temporarily bonded in advance.
And a method for producing the same.

[0002]

2. Description of the Related Art Conventionally, overhead projectors (OHs) have been used in lectures, school lessons, and other briefings.
P) is widely used. The transparent sheet used in the OHP is a sheet or a film mainly composed of a transparent resin such as polyester or polypropylene and having a thickness of several tens to several hundreds of micrometers. Has been adopted. When an image is formed on the OHP sheet by the thermal transfer method, it is possible to separately supply the thermal transfer sheet and the OHP sheet to the printer. However, since the OHP sheet is usually a sheet-fed type, the OHP sheet surface is set in advance. It is preferable to use a so-called co-winding thermal transfer sheet in which the thermal transfer sheet is temporarily fixed so that it can be peeled off. In this case, it is possible to form an OHP image with a simple printer.

[0003]

BRIEF are trying to solve problems] In the case of forming the co-winding the thermal transfer sheet is normally forming a pressure-sensitive adhesive layer from the pressure-sensitive adhesive of an aqueous emulsion system in the ink layer surface of the thermal transfer sheet but, OHP sheet in this case There is a problem that the hydrophobicity is high and the adhesion between the two is insufficient. O for this
Adhesive aqueous emulsion type even attempt to form an adhesive layer on HP sheet surface is uniform coating is difficult, yet another problem surfaces of OHP sheet sticky also printing surface as could coating occurs I do. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide an OHP thermal transfer sheet which has good adhesion between the thermal transfer sheet and the OHP sheet and has less stickiness on the OHP sheet surface.

[0004]

The above object is achieved by the present invention described below. That is, the present invention includes a thermal transfer sheet obtained by forming a heat-fusible ink layer on one surface of the substrate film, and releasably adhered a transparent resin sheet provided with a pressure-sensitive adhesive layer obtained by adding port Resocia titanate A thermal transfer sheet for OHP, comprising an adhesive and a polysocyanate
The transparent resin sheet organic solvent solution was applied and dried to form a pressure-sensitive adhesive layer containing bets, peelably to the ink layer of the thermal transfer sheet obtained by forming a heat-fusible ink layer on one surface of the substrate film This is a method for producing a thermal transfer sheet for OHP, which is characterized by bonding.

[0005]

[Action] By using the transparent resin sheet provided with an adhesive layer comprising a polyisocyanate, a good adhesion to the thermal transfer sheet, little OHP sheet with stickiness O
A thermal transfer sheet for HP is provided.

[0006]

Next, the present invention will be described in more detail with reference to preferred embodiments. FIG. 1 is a sectional view of a preferred example of the thermal transfer sheet of the present invention. The thermal transfer sheet of the present invention comprises a thermal transfer sheet A and a transparent resin sheet B as shown.
This is a heat transfer sheet for OHP, which is releasably adhered by a pressure-sensitive adhesive layer C containing polyisocyanate . In the thermal transfer sheet A, a heat-meltable ink layer 2 composed of a pigment and a binder is formed on a base film 1 as shown in the figure, and the heat-fusible ink layer 2 is separated between the base film 1 and the ink layer 2 as necessary. A layer 3 is formed, and a slip layer 4 is formed on the back surface.

As the substrate film used in the thermal transfer sheet of the present invention, the same substrate film as used in the conventional thermal transfer sheet can be used as it is, and other materials can be used. Not restricted. Specific examples of preferred base film include, for example, polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chloride rubber, ionomer, etc. Paper, such as plastic, condenser paper, paraffin paper, and non-woven fabric, and a base film in which these are combined. The thickness of the base film can be appropriately changed depending on the material so that the strength and the thermal conductivity become appropriate, but the thickness is preferably, for example, 2 to 25 μm.

[0008] The hot-melt ink layer provided on the base film may be composed of a pigment and a binder, and may further contain various additives as necessary. The pigment is preferably carbon black for monochromatic printing, and chromatic pigments such as cyan, magenta, and yellow are used for multicolor printing. It is generally preferred that these pigments be used in an amount of about 5 to 70% by weight in the ink layer. As the binder, a mixture containing wax as a main component and other derivatives of wax and a drying oil, resin, mineral oil, cellulose, or rubber is used. Representative examples of the wax include microcrystalline wax, carnauba wax, and paraffin wax. Furthermore, Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, whale wax, Ibota wax, wool wax, shellac wax, candelilla wax, petrolactam,
Various waxes such as polyester wax, partially modified wax, fatty acid ester and fatty acid amide are used. In the present invention, the wax can be mixed with a thermoplastic resin having a relatively low melting point to improve the adhesion of the ink to the material to be transferred.

As a method for forming a hot-melt ink layer on a substrate film, necessary components such as a binder mainly composed of a pigment and a wax are melt-kneaded and applied by a hot-melt coating method or the like. A method in which an emulsion obtained by emulsifying or dispersing a binder mainly composed of a wax in an aqueous medium which may contain an alcohol or the like, and an emulsion ink obtained by mixing an aqueous dispersion of a pigment, and the like are formed by coating and drying. It is preferable to use a thermoplastic resin in addition to the wax as a binder,
10 to 10 parts by weight of thermoplastic resin per 100 parts by weight of wax
It is preferable to use 0 parts by weight. The ink layer thus formed is usually preferably formed to a thickness of about 2 to 20 μm. In forming the ink layer, a transparent release layer made of wax may be formed on the surface of the base film in advance so that the transferred image has a surface layer after the transfer. Such a release layer is also preferably formed from the wax as described above. Such a wax layer generally has a thickness of about 1 to 5 μm.

As the material to be transferred B, any transparent resin sheet may be used as long as it is conventionally used as an OHP sheet. For example, polyester, polypropylene,
Examples include sheets or films of cellophane, polycarbonate, cellulose acetate and the like. The thickness of these transparent resin sheets may be in the range of tens to hundreds of μm.

The pressure-sensitive adhesive layer C for temporarily bonding the thermal transfer sheet A and the material to be transferred B may be any conventionally known pressure-sensitive adhesive containing polyisocyanate , but a preferable pressure-sensitive adhesive is a pressure-sensitive adhesive resin having a low glass transition temperature. To polyisocyanate
Consisting of added . Adhesion of such pressure-sensitive adhesive layer (g)
Cuts out a sample of 25 mm (width) x 55 mm (length) and uses a surface friction meter (HEIDON-14, manufactured by Shinto Kagaku) at 1800 mm / min. Is preferably in the range of 300 to 2000 g when measured at a pulling speed of. When the adhesive strength is less than the above range, the adhesive strength between the thermal transfer sheet and the material to be transferred is too low, the two easily peel off, and the thermal transfer sheet is more likely to wrinkle. On the other hand, if the adhesive strength exceeds the above range, the adhesive strength is sufficient, but the ink layer is easily transferred to the material to be transferred even in the non-printed area, and the material to be transferred is contaminated. However, when the amount of the thermoplastic resin in the ink layer is, for example, an ethylene-vinyl acetate copolymer having a vinyl acetate content of 28% by weight,
When the solid content in the ink layer is 9% by weight or more, the adhesiveness between the base film and the ink layer is increased accordingly.
Even when the amount is in the range of 000 g, a thermal transfer sheet that does not cause contamination of the transfer material can be obtained.

The adhesive resin has a glass transition temperature of -90.
C. to -60.degree. C., and examples of such an adhesive resin include a rubber-based adhesive resin, an acrylic-based adhesive resin, and a silicone-based adhesive resin. Although it can be used in the present invention, particularly preferred in the present invention are acrylic pressure-sensitive adhesives. In the present invention, the adhesive resin is preferably used as an organic solvent solution having a solid content of about 5 to 40% by weight such as toluene, xylene, methyl ethyl ketone, ethyl acetate, and butyl acetate. In addition, when such an organic solvent solution is used, good adhesiveness can be imparted to the transparent resin sheet, but as it is, a sticky feeling remains on the surface of the transparent resin sheet,
In the present invention, you combination polyisocyanate. Any conventionally known port Such polyisocyanate
Although polyisocyanate can also be used, particularly preferred Po
Liisocyanate is a polyisocyanate such as toluene diisocyanate-isocyanurate, isophorone diisocyanate trimethylolpropane adduct,
It is preferable to use 5 to 10 parts by weight per 100 parts by weight of the adhesive. If the amount of the polyisocyanate is too small, a sticky feeling remains, while if it is too large, the tackiness is undesirably reduced. The pressure-sensitive adhesive layer has a thickness of 0.1
〜１０10 μm (0.1 to 5 g / m ² as solid coating amount)
Is preferred.

The adhesion between the thermal transfer sheet A and the transfer material B is as follows.
This is performed by continuously adhering the thermal transfer sheet while forming an adhesive layer on the surface of the transparent resin sheet, and winding it up in a roll shape. May be placed on the outside, and these may be cut into single sheets. The above is the basic configuration of the co-winding thermal transfer sheet of the present invention. Of course, as shown in FIG. 1, a slip layer 4 for preventing adhesion of the thermal head and improving the slipperiness is provided on the back surface of the thermal transfer sheet. In the field of thermal transfer sheets, for example, a wax layer or mat layer 3 serving as a surface layer after transfer is provided between the material film and the ink layer to make the print matte, and to make the ink layer a hue other than black. Any of the well-known techniques can be added to the thermal transfer sheet of the present invention.

The above-described thermal transfer sheet of the present invention is, for example,
The printer is set on a printer or plotter, conveyed as indicated by an arrow in FIG. 2, and the thermal transfer head 5 peels off the transferred material B after printing, thereby forming a desired image 6 on the transferred material B.

[0015]

The present invention will be described more specifically below with reference to examples and comparative examples. In the following description, parts and% are based on weight unless otherwise specified.

Example 1 A 4.5 μm-thick polyethylene terephthalate film having a slip layer provided on the back surface was used as a base film, and the following ink composition was coated on the surface with a solid content of 4 g / m 2.
^An ink layer was formed by coating at a ratio of ² to obtain a thermal transfer sheet. Ink composition carnauba wax 15 parts Ethylene / vinyl acetate copolymer 10 parts Carbon black 20 parts Polyethylene wax 55 parts Petroleum resin 10 parts Next, an adhesive having the following composition has a coating amount of 0.5 g when dried by a gravure coating method. / M ² on a 100 μm-thick polyester sheet and dried.
° C., the thermal transfer sheet and laminated with nip pressure 5 kg / cm ^2, to obtain a thermal transfer sheet of the present invention. Adhesive composition Acrylic adhesive resin (glass transition temperature -58 ° C) 10 parts Polyisocyanate 1 part Toluene 44 parts Methyl ethyl ketone 44 parts

Example 2 An ink layer was formed by applying the following ink composition to one surface of the same base film as in Example 1 at a solid content of 2 g / m ^2. A thermal transfer sheet was used. Ink composition carnauba wax 15 parts Ethylene / vinyl acetate copolymer 5 parts Carbon black 20 parts Polyethylene wax 55 parts Petroleum resin 10 parts Next, the adhesive amount of the following composition when dried by the gravure coating method is 0.5 g. / M ² on a 120 μm thick polypropylene sheet and dried at a nip temperature of 5
At 0 ° C., a nip pressure of 5 kg / cm ² was applied to the thermal transfer sheet to obtain a thermal transfer sheet of the present invention. Adhesive composition Acrylic adhesive resin (glass transition temperature -52 ° C) 10 parts Polyisocyanate 2 parts Toluene 44 parts Methyl ethyl ketone 44 parts

Example 3 A 6.0 μm thick polyethylene terephthalate film having a slip layer provided on the back surface was used as a base film, and the following ink composition was coated on the surface at a solid content of 2 g / m 2.
^An ink layer was formed by coating at a ratio of ² to obtain a thermal transfer sheet. Ink composition carnauba wax 15 parts Ethylene / vinyl acetate copolymer 10 parts Carbon black 25 parts Polyethylene wax 55 parts Petroleum resin 10 parts Next, an adhesive having the following composition has a coating amount of 0.5 g when dried by a gravure coating method. / M ² was applied to a cellulose triacetate sheet having a thickness of 150 μm and dried, and bonded to the thermal transfer sheet at a nip temperature of 50 ° C. and a nip pressure of 5 kg / cm ² to obtain a thermal transfer sheet of the invention. Adhesive composition Acrylic adhesive resin (glass transition temperature -60 ° C) 20 parts Polyisocyanate 1 part Toluene 44 parts Methyl ethyl ketone 44 parts

Comparative Example 1 A thermal transfer sheet of Comparative Example was obtained in the same manner as in Example 1 except that a pressure-sensitive adhesive containing no polyisocyanate was used. Each of the thermal transfer sheets of the above Examples and Comparative Examples was loaded into a large printer for printing, and the transparent resin sheet was peeled off. In the case of the Example, no stickiness was observed on the surface of the resin sheet. In the case of the example, the surface of the resin sheet was entirely solid.

[0020]

According to the present invention as described above, the polyisocyanate
By using the transparent resin sheet provided with an adhesive layer containing bets, it has good adhesion to the thermal transfer sheet, OHP
A thermal transfer sheet for OHP with less stickiness of the sheet is provided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a cross section of a thermal transfer sheet of the present invention.

FIG. 2 is a diagram schematically illustrating a cross section of the thermal transfer sheet of the present invention.

[Explanation of symbols]

 A: Thermal transfer sheet B: Transparent resin sheet C: Adhesive layer 1: Base film 2: Ink layer 3: Release layer 4: Slip layer 5: Thermal head 6: Image

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-56-121791 (JP, A) JP-A-2-38094 (JP, A) JP-A-3-1986 (JP, A) 22860 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (2)

(57) [Claims] 1. A thermal transfer sheet having a heat-fusible ink layer formed on one surface of a substrate film, and a polysocyanate
OHP thermal transfer sheet, characterized in that by comprising releasably adhered a transparent resin sheet provided with an adhesive layer was added. Wherein the organic solvent solution coating and drying a transparent resin sheet to form a pressure-sensitive adhesive layer containing an adhesive and Po Resocia sulfonate, to form a heat-fusible ink layer on one surface of the substrate film A method for producing a thermal transfer sheet for OHP, wherein the thermal transfer sheet is releasably adhered to an ink layer of the thermal transfer sheet.