JPH06255275A - Thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To provide a thermal transfer image receiving sheet having sufficient forming strength, transfer accepting properties, transfer density properties, resistance to scratching, resistance to wear, and outdoor weather resistance by providing an image receiving layer mainly composed of a polycaprolactone having a main chain structure shown by a specific formula on a substrate. CONSTITUTION:A thermal transfer image receiving sheet is formed by providing an image receiving layer 2 mainly composed of a polycaprolactone having a main chain structure shown by formula I on a substrate 1. The polycaprolactone is a kind of polyester having a main chain structure shown by the formula I and is characterized by its outdoor weather resistance, its high forming strength, and its clear melting point of 100 deg.C or lower, which is based on its high crystallizability in spite of its high molecular weight in comparison with a conventional polyethylene terephthalate polyester. In this manner, the sheet has superior heat sensitive characteristics that it keeps the high forming strength below the melting point without tending to soften but sharply melts when reaching the melting point.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-melting type image-receiving sheet for heat-sensitive transfer, and more specifically, it has a heat-sensitive transfer image-receiving property, and has transferability, transfer adhesion, scratch resistance, abrasion resistance and outdoor weather resistance. The present invention relates to a heat-sensitive transfer image-receiving sheet for obtaining a recorded matter having excellent properties.

[0002]

2. Description of the Related Art In recent years, heat-melt type thermal transfer recording apparatuses are non-impact, noise-free, maintenance-free, low price,
Because of its small size and light weight, it is widely used in facsimiles, word processors, computer terminal printers, etc. A general heat-sensitive transfer material is a thin plastic film substrate such as a polyester film (polyethylene terephthalate, polyethylene naphthalate, etc.) provided with a heat-meltable ink layer containing wax as a main component. The surface and the surface to be transferred, such as plain paper, are superposed, and the heat-meltable ink is transferred from the back surface of the base material to the plain paper surface by heating using a thermal head or the like for recording.

More recently, with the spread of factory automation, store automation and the like, heat-sensitive transfer materials have been used in the fields of labels and bar codes, and recorded materials are required to have various resistances such as scratch resistance and abrasion resistance. As a result, a heat-sensitive transfer material having a transfer layer containing a resin as a main component has been developed.
Various materials such as synthetic paper and plastic sheets are beginning to be used. However, the heat-sensitive transfer material provided with a transfer layer containing a resin as a main component is difficult to transfer to plain paper, synthetic paper,
Although it is transferred to a plastic sheet or the like, the transfer adhesion is insufficient, and there is a drawback that it can be easily removed by adhesive peeling with cellophane tape.

Regarding the image receiving material for improving the resistance to recorded matter, Japanese Patent Laid-Open No. 63-137892 discloses that the melting point on the substrate is 135 ° C.
The following image-receiving sheets provided with a thermoplastic resin layer are disclosed, but the thermoplastic resin layers exemplified as examples are polyethylene or polyolefins having a melting point of 100 to 135 ° C., and thus are usually OHP films other than paper. For example, a substrate such as a polyethylene terephthalate film that is often used for the above has poor adhesion, and the melting point is rather high, so that a thermal transfer material using a resin type thermal transfer layer has a drawback that transferability is poor.

Further, Japanese Patent Laid-Open No. 1-120389 discloses an image-receiving sheet in which a lubricant and an image-receiving layer mainly composed of a thermoplastic resin having a Tg of 50 to 100 ° C. are provided on a substrate. When a lubricant such as wax, synthetic wax, or higher fatty acid metal salt is contained, the surface gloss of the image-receiving layer is inferior, and when used for outdoor applications, the lubricant is inferior in weather resistance and deteriorates due to oxidation or hydrolysis. However, there were defects such as deterioration in gloss.

Usually, a thermoplastic resin having a melting point or a softening point of 100 ° C. or lower is used for the image receiving layer in order to improve the transferability and the transfer adhesion. However, a sharp melting point of such a thermoplastic resin is used. Generally, the polymer has a low molecular weight (approximately 2000 or less) and is an oligomer-like polymer, so that the film-forming strength is low and there is almost no weather resistance. It deteriorated and had a problem in practical use. On the other hand, those showing a softening point without having a sharp melting point have a tack around the softening point from room temperature (approximately 30 ° C), so that when the transfer recorded matter is used for outdoor applications, the surface of the image receiving layer is exposed to sunlight. Since it softens and develops adhesiveness due to temperature rise and the like, problems such as dust adhesion and adsorption of soot and the like and black stains may occur. Also, if the melting point or softening point is 100 ° C or higher, sufficient transferability is obtained unless high energy is applied to overload the thermal head when using a thermal transfer material containing resin as the main component. However, there arises a problem that transfer adhesion cannot be obtained.
Therefore, in the conventional method, sufficient transfer characteristics are obtained when a thermal transfer material having a transfer layer containing a resin as a main component is used.
It was not possible to obtain an image-receiving sheet for thermal transfer which has ink adhesion, scratch resistance and abrasion resistance, and is also excellent in outdoor weather resistance.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors to solve the above-mentioned drawbacks of the prior art, polycaprolactone having a specific structure in its main chain has high crystallinity, resulting in sharpness. It has a melting point and does not soften at lower temperatures, does not tack at room temperature, and has sufficient film-forming strength, transferability, transfer adhesion, scratch resistance, abrasion resistance, and outdoor weather resistance. The inventors have found that they have the present invention and have reached the present invention.

[0008]

Means for Solving the Problems That is, the present invention provides an image-receiving sheet for heat-sensitive transfer, which comprises an image-receiving layer containing a polycaprolactone main chain having a structure of the following general formula (1) as a main component on a substrate. provide.

[Chemical 2]

The surface of the image-receiving layer of the image-receiving sheet for heat-sensitive transfer of the present invention and the transfer surface of the heat-sensitive transfer material comprising a heat-transfer layer containing a resin as a main component on one surface of the substrate are superposed to form a heat-sensitive transfer material. When transferring the thermal transfer layer to the image receiving layer by heat and pressure of the thermal head from the surface opposite to the transfer surface, the image receiving layer and the thermal transfer layer are heat-melted and adhered to each other, and at the same time, the excellent transfer property and the strong transfer adhesive force, A recorded matter having excellent scratch resistance, abrasion resistance and weather resistance can be obtained.

The present invention will be described below in detail with reference to the drawings. 1 and 2 are sectional views of an image-receiving sheet for thermal transfer of the present invention. The image-receiving sheet for heat-sensitive transfer of the present invention has a structure in which an image-receiving layer is provided on the surface of a base material such as a plastic sheet. Specifically, as shown in FIG.
An image-receiving layer (2) whose main chain is mainly composed of polycaprolactone having the structure of the above-mentioned general formula (1) is provided on (1). Further, as shown in FIG. 2, a release paper (4) may be provided on the side of the substrate opposite to the image receiving layer via an adhesive layer (3) as required.

Polycaprolactone used in the present invention is a kind of polyester, and has a main chain of the above general formula.
It has the structure of (1) and has excellent outdoor weather resistance and strong film-forming strength, and at the same time has a high molecular weight (for example, 10,000 to 10,000
However, it is characterized by having a clear melting point of 100 ° C or less due to high crystallinity. For this reason, it has an excellent heat-sensitive property that it does not tend to soften until reaching the melting point, maintains high film-forming strength, and melts sharply when reaching the melting point. Despite having excellent heat-sensitive properties due to this property, when the image-receiving sheet after pattern transfer is used outdoors as a display object, etc. It is possible to prevent the sheet surface from being contaminated due to, and it has excellent weather resistance. As such polycaprolactone, several kinds of polycaprolactone having a melting point of 60 ° C. and different molecular weight distributions are commercially available from Daicel Chemical Industries, Ltd. under the trade name “Placcel”.

Further, the image-receiving layer may contain a fluorine-containing compound having a polyfluoro group or a silicon-modified resin having a polyorganosiloxane unit for the purpose of further improving outdoor stain resistance. The fluorine-containing compound may be one in which the side chain of an acrylic resin is arranged in the main chain of a fluororesin, or a graft polymer (a low molecular oligomer may be used) in which the side chain of a fluororesin is arranged in the main chain of an acrylic resin. A copolymer (a low molecular weight oligomer may be used) of a polyfluoro group-containing vinyl monomer and another vinyl monomer is preferable. The content of the fluorine-containing compound in the image-receiving layer can be appropriately selected within the range of 0 to 50% by weight depending on the kind of the fluorine-containing compound,
1 to 20% by weight is preferable. If it is added over this range, the transferability may be deteriorated.

As the silicone-modified resin, a polymer obtained by graft-modifying or block-modifying polyorganosiloxane on the main chain is preferable, and among them, a compound (or prepolymer) having two or more hydroxyl groups in the molecule and a polymer in the molecule. Silicon-modified polyurethane resin obtained by polyaddition reaction with polyorganosiloxane having one or more hydroxyl groups and a compound (or prepolymer) having two or more isocyanate groups in the molecule, or one or more acrylic monomers A silicone-modified acrylic resin obtained by polymerizing a polyorganosiloxane having a radical-polymerizable double bond is preferred. When a conventionally known silicone oil is used, so-called bleeding or the like may occur, which may result in defective transfer or deterioration in adhesion.

The content of polyorganosiloxane in all the constituents of the silicone-modified resin is preferably 10 to 70% by weight, more preferably 20 to 50% by weight. If the content is less than this, the characteristics as a silicone-modified resin cannot be obtained, and if it is more than the above, the properties similar to the silicone rubber of polyorganosiloxane alone are not obtained, which is not preferable. Depending on the type of silicon-modified resin, the content of silicon-modified resin in the image-receiving layer may range from 0 to
It can be appropriately selected within the range of 50% by weight, but preferably 1 to 20.
Weight% is good. If it is added over this range, the transferability may be deteriorated.

Further, other thermoplastic resins may be added to the image-receiving layer, if necessary, within a range not impairing the properties of polycaprolactone, and one kind or two or more kinds may be used in combination. The content of the thermoplastic resin in the image receiving layer is 0 to 50.
It can be appropriately selected within the range of wt%, but it is preferably not added if possible. When the content is large, problems such as dust and dirt adhering to the image-receiving layer to cause transfer failure, or blackening due to soot during outdoor exposure may occur. Alternatively, the transferability may be deteriorated.

Examples of thermoplastic resins include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers, polyethylene, polypropylene, polyacetal,
Ethylene-vinyl acetate copolymer, ethylene- (meth) acrylic acid ester copolymer, styrene- (meth) acrylic acid ester copolymer, polystyrene, acrylic resin,
Polyamide resin, cellulose derivative, epoxy resin, xylene resin, ketone resin, petroleum resin, rosin or its derivative, coumarone indene resin, terpene resin, polyurethane resin, polyester resin, chlorinated polyolefin, styrene-maleic anhydride resin, Examples thereof include resins such as polyvinylpyrrolidone, vinylpyrrolidone-vinyl acetate copolymer, styrene-butadiene rubber, polyvinyl butyral, nitrile rubber, acrylic rubber, and ethylene-propylene rubber.

The image-receiving sheet for heat-sensitive transfer can be colored in various colors such as white and transparent. That is, an image receiving layer may be provided on a colored plastic sheet, for example, a plastic sheet in which a pigment is kneaded, or a plastic sheet colored on either side by printing or vapor deposition, or may be white or transparent. An image receiving layer containing a colorant may be provided on the plastic film. When a white or transparent plastic sheet is used, by incorporating a coloring material in the image receiving layer, it is possible to easily obtain image receiving sheets for thermal transfer of various colors.

As the colorant, conventionally known pigments such as carbon black, aniline black, titanium oxide, phthalocyanine type, monoazo type, disazo type, nitro type, nitroso type, perylene type, isoindolinone type and quinacridone type pigments. Materials used for ordinary inks such as dyes such as azo, anthraquinone, and nigrosine are used, but pigments are preferable for obtaining a transferred material having particularly good weather resistance, and among them, carbon black, fast yellow, and cadmium yellow. , Yellow iron oxide, chromophthal yellow, anthrapyrimidine yellow, isoindolinone yellow, copper azomethine yellow, benzimidazolone yellow, quinophthalone yellow, nickel dioxine yellow, flavanthron yellow, yellow lead, titanium yellow, disazo yellow , Benzimidazolone orange,
Pyranthrone Orange, Perinone Orange, Para Red, Lake Red, Naphthol Red, Pyrazolone Red, Permanent Red, Madare Lake, Thioindigo Bordeaux, Bengala, Lead Red, Cadmium Red, Quinacridone Magenta, Perylene Vermillion, Perylene Red, Chromophtal Scarlet, Anthron red, dianthraquinolyl red, perylene maroon, benzimidazolone carmine, perylene scarlet, quinacridone red, pyranthrone red, manganese violet, dioxazine violet, phthalocyanine blue, navy blue, cobalt blue, ultramarine blue, indanthrone blue, phthalocyanine green. , Pigment green, nickel azo yellow, chromium oxide, viridian, benzimidazolone brown Bronze powder, white lead, zinc white, lithopone, titanium oxide, pearl pigments, and the like are preferable.
Further, a fluorescent pigment may be used depending on the application.

Further, for the purpose of improving the weather resistance, an ultraviolet absorber, an ultraviolet blocker or the like may be added to the image-receiving layer. As an example of such an ultraviolet absorber, light having a wavelength of 290 to 400 nm is used. Examples of the compound to be absorbed include benzophenone-based, benzotriazole-based, salicylic acid phenyl ester-based, cyanoacrylate-based, cinnamic acid-based, aminobutadiene-based compounds and the like. Further, examples of the ultraviolet blocking agent include those obtained by pulverizing titanium oxide, zinc oxide, talc, kaolin, calcium carbonate, iron oxide and the like into ultrafine particles.

Further, other additives such as dispersants, antistatic agents, plasticizers, antioxidants, etc. may be used in combination for the purpose of adjusting coating suitability and coating film characteristics. Examples of antistatic agents include polyoxyethylene alkyl amines,
Polyoxyalkylamide, polyoxyethylene alkyl ether, glycerin fatty acid ester, sorbitan fatty acid ester, alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate alkyl phosphate, quaternary ammonium sulfate, etc. are mentioned, and particularly transfer void (void) in thermal transfer recording. It is effective in preventing dust collection due to static electricity, which causes
Examples of the plasticizer include basic carboxylic acid compounds such as phthalic acid, isophthalic acid, tetrahydrophthalic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, trimellitic acid and oleic acid, and a monovalent or polyvalent alcohol. Examples thereof include low molecular weight ester plasticizers with compounds, alkyd liquid plasticizers, and oxirane oxygen-containing epoxy plasticizers, which can be freely selected.

As the base material, synthetic paper, polyester, polyvinyl chloride, polyurethane, poly (meth) acrylic acid ester, polycarbonate, polyethylene, polypropylene, polyamide, cellulose-based material, etc., having a thickness of 10 to 500 can be used.
A plastic sheet having a thickness of 50 μm is used, but a plastic sheet having a thickness of 50 to 500 μm such as soft polyvinyl chloride, polyester, or synthetic paper is preferable in terms of excellent weather resistance, flexibility, and beauty. Further, an adhesive layer may be provided between the image receiving layer and the substrate for the purpose of improving the adhesion between the image receiving layer and the substrate. In this case, the material used for the adhesive layer is not particularly limited. As a method for providing the image receiving layer on the surface of the substrate, a solvent coating method in which a composition which constitutes the image receiving layer is dissolved or dispersed in a solvent or water and dried, or a composition which constitutes the image receiving layer is heated and melted. A method such as a hot-melt coating method for coating is then used. The film thickness of the image receiving layer is preferably about 0.1 to 10 μm, and the solvent coating method is preferable for a thin film and the hot melt coating method is preferable for a thick film. More preferably, the film thickness is 0.2 to 2 by the solvent coating method.
It is preferable to set the thickness to about μm.

[0022]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples. In addition, "part" in each Example shows a "weight part."

Example 1 An image receiving sheet 1 was prepared by coating a coating solution having the following composition to a thickness of 1 μm on one side of a soft vinyl chloride sheet having a thickness of 100 μm by a gravure coating method.
Got Polycaprolactone ("Plaxel H7" manufactured by Daicel Chemical Industries) 10 parts Toluene 50 parts Methyl ethyl ketone 40 parts

Example 2 An image receiving sheet 2 was obtained by coating one side of a 100 μm thick polyethylene terephthalate sheet with a coating solution having the following composition in the same manner as in Example 1. Polycaprolactone (Daicel Chemical Industries "Plaxel H7") 9.5 parts Fluorine modified resin (Asahi Glass "Surflon S381") 0.5 parts Toluene 50 parts Methyl ethyl ketone 40 parts

Example 3 An image receiving sheet 3 was obtained by coating one surface of a polyethylene terephthalate sheet having a thickness of 100 μm with a coating solution having the following composition in the same manner as in Example 1. Polycaprolactone ("Plaxel H7" manufactured by Daicel Chemical Industries) 18 parts Silicon modified urethane resin ("Dialomer SP2105" manufactured by Dainichiseika) 2 parts Toluene 50 parts Methyl ethyl ketone 40 parts

Example 4 An image receiving sheet 4 was obtained by coating one side of a 100 μm thick soft vinyl chloride sheet with a coating solution having the following composition in the same manner as in Example 1. Polycaprolactone ("Plaxel H7" manufactured by Daicel Chemical Industries) 15.5 parts Silicon-modified acrylic resin ("Cymac US-350" manufactured by Toagosei Chemical Co., Ltd.) 0.5 part Yellow pigment ("Rionol Yellow 1308" manufactured by Toyo Ink Mfg. Co., Ltd.) 4 parts Toluene 40 parts Methyl ethyl ketone 40 parts

Comparative Example 1 An image receiving sheet 4 was obtained by coating one side of a soft vinyl chloride sheet having a thickness of 100 μm with a coating solution having the following composition in the same manner as in Example 1. Epoxy resin ("Epicoat 1002" manufactured by Yuka Shell Epoxy) 20 parts Toluene 40 parts Methylethylketone 40 parts [Comparative Example 2] A coating solution having the following composition was applied to one surface of a soft vinyl chloride sheet having a thickness of 100 µm as in Example 1. To obtain an image receiving sheet 5. Polyester resin ("Byron 200" manufactured by Toyobo) 20 parts Toluene 40 parts Methyl ethyl ketone 40 parts

A heat-resistant layer was provided on the surface of the image-receiving layer of each of the image-receiving sheets obtained in Examples and Comparative Examples and one side of a 6 μm polyethylene terephthalate film, and the acrylic resin and the pigment were provided on the opposite side through a release layer. The transfer ink surface of the heat-sensitive transfer material provided with the heat-transferable ink as the main component was overlaid and heat-transferred from the heat-resistant layer surface of the heat-sensitive transfer material with a thermal head to obtain a transfer recording material. The transferability of the obtained transfer recording material was visually evaluated for resolution, and the transfer adhesion was evaluated by a method in which cellophane tape was attached to the recording portion and peeled off at once. In addition, the scratch resistance is measured by a pencil hardness test (JIS
K-5401). The rub resistance was evaluated by the Gakushin-type dyeing fastness rub test (JIS L-0823) on the recorded part. For outdoor weather resistance, the recorded matter was mounted on an outdoor exposure test stand and exposed for 6 months, and the degree of stain was compared. The results are shown in Table 1.

[0029]

[Table 1]

As shown in Table 1, in Examples 1 to 4, good results were obtained in all evaluation items. On the other hand, in Comparative Example 1, since the thermoplastic resin used for the image receiving layer has a sharp melting point (80 ° C.), good transferability can be obtained, but since the film forming strength is low, transfer adhesion and scratch resistance are low. Since the scratch resistance and the abrasion resistance are very poor and the molecular weight is low, the weather resistance is inferior, so that it weathered due to deterioration in the outdoor exposure test. In Comparative Example 2, since the thermoplastic resin used for the image receiving layer has a strong film-forming strength, the scratch resistance and the abrasion resistance are good, but the softening point (160 ° C.) is high, and therefore the outdoor weather resistance is high. Although good, the thermal sensitivity is low and the transferability and transfer adhesion are poor.

[0031]

EFFECTS OF THE INVENTION By using the image-receiving sheet for heat-sensitive transfer of the present invention, transferability, transfer adhesion, scratch resistance, abrasion resistance,
A recorded matter having excellent weather resistance can be obtained, and even if the recorded matter is used for outdoor use, it does not stain due to dust adhesion or adsorption of soot and the like.

[Brief description of drawings]

FIG. 1 is a sectional view of an image-receiving sheet for thermal transfer of the present invention.

FIG. 2 is a sectional view of an image-receiving sheet for thermal transfer of the present invention.

[Explanation of symbols]

(1) Base material (2) Image receiving layer (3) Adhesive layer
(4) Release paper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Motohiko Kashiwaoka 2-33 Kyobashi, Chuo-ku, Tokyo Toyo Inki Manufacturing Co., Ltd.

Claims (2)

[Claims] 1. An image-receiving sheet for heat-sensitive transfer, comprising an image-receiving layer having a main chain of polycaprolactone having a structure of the following general formula (1) as a main component, provided on a substrate. [Chemical 1] 2. The image-receiving sheet for thermal transfer according to claim 1, wherein the image-receiving layer further contains a fluorine-containing compound having a polyfluoro group or a silicon-modified resin having a polyorganosiloxane unit.