JP2006248087A - Sublimation transferred image accepting sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sublimation transferred image accepting sheet which brings about an excellent image quality of a highlight portion of a transferred image and does not cause a flaw, printing nonuniformity, printing creases or the like on the occasion of printing. <P>SOLUTION: The sublimation transferred image accepting sheet is constituted by providing an accepting layer on a base. The sheet contains at least a thermoplastic resin (A), at least one kind (B) out of a polyalkylene oxide and its isocyanate modified matter and an isocyanate compound (C). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sublimation transfer image receiving sheet that is used in superposition with a sublimation transfer sheet. Specifically, the image quality of a highlight portion of a transferred image is uniform and good, and scratches are formed during image formation (printing). The present invention relates to a sublimation transfer image receiving sheet in which wrinkles such as printing unevenness and printing wrinkles do not occur.

  In recent years, a so-called sublimation type thermal recording system has attracted attention as a kind of full-color printing system because of its characteristics such as fidelity of color tone reproduction and high image quality. This method uses a sublimation transfer sheet (hereinafter referred to as a transfer sheet) obtained by applying a heat sublimable dye on a substrate, and a thermal head having a heating element that selectively applies a voltage according to a recording signal. And a sublimation transfer image receiving sheet (hereinafter referred to as an image receiving sheet) in which a layer having dyeability (hereinafter referred to as a receiving layer) provided on another substrate is provided, the thermal head is interposed via the transfer sheet. By applying a voltage to the heating element based on the recording information, the dye is transferred and fixed (transferred) to the receiving layer of the image receiving sheet by adhesion, adsorption, dyeing, etc., and a desired recorded image is obtained. It is a recording method to obtain.

  The receiving layer of the image receiving sheet used in this sublimation type thermal recording system is generally composed mainly of a resin having high affinity for the dye because it needs to receive and dye the dye sublimated from the transfer sheet. ing.

  As a prior art relating to the resin constituting the main component of the receiving layer, Patent Document 1 discloses that a polyester resin, a polycarbonate resin, a polyvinyl butyral resin, an acrylic resin, a cellulose resin, a polystyrene resin, or the like is used. However, when the receptor layer is mainly composed of a resin having a good dye dyeing property, there is a problem in that the dye tends to bleed out on the surface of the receptor layer because the storability of the transferred image and the fixing property of the dye are poor. there were.

  In order to solve the bleed-out problem, it has been studied to use, as a constituent component of the receiving layer, a resin that has low dye transferability in the receiving layer. However, the use of such a resin can solve the bleed-out problem, but conversely causes a further decrease in dyeing property. There is also a problem that the fastness of the dye such as light resistance and fingerprint resistance is insufficient.

  In order to solve these problems, a method has been proposed in which isocyanate is added to a polyester resin or the like, and the receiving layer-constituting resin is three-dimensionally cross-linked by a reaction between them (Patent Documents 2 and 3). However, according to these methods, although light fastness, fastness and the like are improved, since sufficient dyeing property cannot be obtained, the highlight portion of the image transferred to the receiving layer becomes rough and uniform. There was a problem that good image quality could not be obtained.

  Therefore, attempts have been made to add various materials to the constituent resin of the receiving layer in order to improve dyeability. For example, Patent Document 4 describes that polyethylene glycol (polyethylene oxide) having a low molecular weight of 200 to 20000 is added.

JP 60-25793 A JP-A-2-34392 JP-A-2-86494 JP 7-214919 A

  However, when polyethylene oxide is added as described above, the dyeing property itself is improved, and the image quality of the highlighted portion of the transferred image is also improved. On the other hand, the addition layer softens the surface of the receiving layer. There has been a problem that wrinkles such as surface scratches, printing unevenness, and printing wrinkles are easily formed during printing. In the sublimation type thermal recording system, since the recording speed is generally slow, these problems are serious obstacles in achieving high speed recording of the system.

  The present invention is intended to solve the problems of such a conventional configuration, and in particular, the image quality of the highlight portion is uniform and a good recorded image is generated with scratches, uneven printing, wrinkles, etc. Therefore, an object of the present invention is to provide a thermal transfer image receiving sheet that can be formed even in high-speed recording.

  The present invention that achieves the above object is a sublimation transfer image-receiving sheet provided with a receiving layer on a substrate, wherein the receiving layer is at least of a thermoplastic resin (A), a polyalkylene oxide, and an isocyanate-modified product thereof. It consists of a sublimation transfer image-receiving sheet characterized by containing one type (B) and an isocyanate compound (C).

  The present inventor has intensively studied to solve the above-described problems of the prior art. As described above, in the prior art, by adding isocyanate, light resistance and fastness are improved, and by adding a low molecular weight polyethylene oxide of 200 to 20000, dyeing property is improved. It was. However, the present inventor does not have a molecular weight of 20000 or less of the prior art with respect to the resin as the main component, but a polyalkylene oxide represented by polyethylene oxide having a higher molecular weight of 20000 to 2000000 and / or its isocyanate-modified product. Are added together with an isocyanate compound at a predetermined ratio to form a receiving layer, so that the image quality is uniformed and improved particularly in the highlight portion by improving the dyeing property, and scratches are imparted by imparting an appropriate surface hardness. The inventors have found that it is possible to effectively prevent the occurrence of uneven printing and wrinkles at the same time, and have completed the present invention.

  Hereinafter, embodiments of the present invention will be described in detail.

  The receiving layer of the sublimation transfer image-receiving sheet according to the present invention contains a thermoplastic resin (A) functioning as a binder resin as the first component. Preferred examples of such thermoplastic resins include polyester resins, polyacrylate resins, polyvinyl acetate resins, styrene acrylate resins, polyurethane resins, polyolefin resins, polystyrene resins, and polyvinyl chloride resins. Resin, polyether resin, polyamide resin, polycarbonate resin, polyethylene resin, polypropylene resin, polyacrylate resin, polyacrylamide resin, polyvinyl chloride resin, polyvinyl butyral resin, polyvinyl acetal resin such as polyvinyl acetoacetal resin, PVC / vinegar Bi-vinyl alcohol copolymer resin, cellulose ester resin, polyol resin, epoxy resin, phenol resin, melamine resin, etc. It can be hand.

  The receiving layer of the sublimation transfer image-receiving sheet according to the present invention contains, as the second component, at least one of polyalkylene oxides such as polyethylene oxide and polypropylene oxide and isocyanate-modified products thereof (B).

  These polyalkylene oxides (B) are resins obtained by polymerizing alkylene oxide using a catalyst such as diethyl zinc-hydrogen. As the alkylene oxide, one kind or two or more kinds such as ethylene oxide, propylene oxide, and butylene oxide are used. In the present invention, as the polyalkylene oxide, a resin having a substituent such as an alkyl group in the main chain or side chain may be used.

  The average molecular weight of the polyalkylene oxide (B) is preferably 20,000 or more and 2,000,000 or less. Here, if the average molecular weight is less than 20000, the receiving layer is softened, and wrinkles such as surface scratches, uneven printing, and wrinkles are likely to be formed. As the peeling sound of the transfer sheet increases, printing unevenness occurs and the uniformity of the highlight portion of the image cannot be obtained.

  Moreover, it is more preferable that the average molecular weight of the polyalkylene oxide (B) is 50,000 or more, since the uniformity of the highlight portion of the transferred image is improved.

  As specific examples of the polyalkylene oxide (B) having the average molecular weight as described above, PEG2000 to PEG2000000 (trade name of polyethylene oxide; the number represents the average molecular weight) manufactured by Sanyo Chemical Industries, Ltd. is preferably used. be able to.

  Furthermore, in the present invention, the same effect can be obtained by using a resin having the same average molecular weight as the isocyanate-modified product (B) instead of or in addition to the polyalkylene oxide. Such a modified (or modified) resin is preferably obtained by adding an isocyanate compound in a proportion of, for example, 0.01 to 5% by weight with respect to the polyalkylene oxide.

  The isocyanate compound for modifying the polyalkylene oxide is a compound having one or more isocyanate groups, such as propyl isocyanate, butyl isocyanate, hexyl isocyanate, dodecyl isocyanate, octadecyl isocyanate, benzyl isocyanate, cyclohexyl isocyanate, Mention may be made of phenyl isocyanate, p-chlorophenyl isocyanate, p-nitrophenyl isocyanate, 2-chloroethyl isocyanate, stearoyl isocyanate, propane diisocyanate, hexane diisocyanate, decane diisocyanate, hexane fluoropropane diisocyanate, 1,4-phenylene diisocyanate, etc. it can. One or more of these isocyanate compounds can be subjected to a reaction with a polyalkylene oxide, and the reaction is generally carried out in a solution state using an appropriate solvent, but the reaction is carried out in a powder or solid state. Is also possible.

  As a specific example of the polyisocyanate-modified isocyanate (B) having an average molecular weight as described above, Melpol F-22 (trade name; average molecular weight 100000) manufactured by Sanyo Chemical Industries, Ltd. is preferably used. Can do.

  The receiving layer of the sublimation transfer image-receiving sheet according to the present invention contains an isocyanate compound (C) as the third component. The isocyanate compound (C) used in the present invention is a polyfunctional isocyanate compound having a structure in which 2 to 5, preferably 2 to 3, isocyanate groups (—NCO) are bonded to a skeleton hydrocarbon group. The skeleton hydrocarbon group in this case includes both an aliphatic group and an aromatic group. Aliphatic groups include chain and cyclic groups, and the carbon number thereof is 1 to 30, preferably 6 to 20. The aromatic group includes those having a benzene ring or a naphthalene ring, and the carbon number thereof is 6 to 12, preferably 6 to 10.

  In the present invention, the isocyanate compound (C) may be an aromatic isocyanate compound. However, when the aromatic isocyanate compound is exposed to light for a long time, the structural change of the dye is promoted to reduce the light resistance. Therefore, aliphatic isocyanate compounds are particularly preferable. Examples of the aliphatic isocyanate compound include, for example, hexamethylene diisocyanate, 1,3,6-undecane triisocyanate, 1,8-diisocyanate-4-isocyanate methyloctane, 1,3,6-hexamethylene triisocyanate, 1, Mention may be made of 6,11-undecane triisocyanate, bicycloheptane triisocyanate, isophorone diisocyanate, bisisocyanate methylcyclohexane, trimethylhexamethylene diisocyanate, and their modified products or derivatives.

  Specific examples of the isocyanate compound (C) as described above include Takenate (trade name) series manufactured by Takeda Pharmaceutical Co., Ltd., Crossnate (trade name) series manufactured by Dainichi Seika Kogyo Co., Ltd., and Nippon Polyurethane Industry. Each product such as Coronate (trade name) series manufactured by Co., Ltd. can be suitably used.

  In the present invention, the compounding ratio of the components (A), (B) and (C) is at least one of polyalkylene oxide and its isocyanate-modified product (B) with respect to 100 parts by weight of the thermoplastic resin (A). Are preferably 1 to 15 parts by weight and the isocyanate compound (C) is preferably 5 to 20 parts by weight.

  When at least one of the polyalkylene oxide and its isocyanate-modified product (B) is less than 1 part by weight relative to 100 parts by weight of the thermoplastic resin (A), it cannot contribute to improving the image quality of the image highlight part. On the other hand, if it exceeds 15 parts by weight, not only the image quality can be improved any more, but also the amount of the binder resin component is relatively reduced, resulting in a decrease in fastness.

  In addition, if the isocyanate compound (C) is less than 5 parts by weight relative to 100 parts by weight of the thermoplastic resin (A), the required crosslink density cannot be obtained, so that the fastness and light resistance are sufficiently improved. However, when the amount exceeds 20 parts by weight, the amount of the binder resin component is relatively reduced, and as a result, characteristics such as image density required for the binder resin are deteriorated.

  As a substrate for providing the receiving layer of the sublimation transfer image-receiving sheet according to the present invention thereon, a film having relatively good heat resistance, for example, polyester, polypropylene, PEEK, PEN, PET, polystyrene, polysulfone, aromatic Various films such as polyamide, polyimide, polycarbonate, and triacetyl cellulose, fine paper, art paper, coated paper, cast coated paper, and the like can be mentioned, among which polyester, PEEK, PEN, aromatic polyamide, and polyimide film are preferable. Moreover, the composite base material which provided these as a core material and provided the foamed film, the non-foamed film, etc. in the single side | surface or both surfaces may be sufficient. Furthermore, if necessary, a layer imparted with plasticity and conductivity may be provided on the back surface of these base materials, and an intermediate layer or the like may be provided on the receiving layer side.

  The sublimation transfer image-receiving sheet according to the present invention includes, on the at least one surface of the substrate, each of the above-described components, and, if necessary, additives known in the art, such as a mold release agent and an ultraviolet absorber. , Antioxidants, light stabilizers, inorganic fillers, etc. added, dissolved in an appropriate organic solvent or dispersed in an organic solvent or water, for example, bar coater, roll coater, air knife coater, gravure It can be obtained by coating by means of a coater, screen printing method, reverse roll coating method, etc. and then drying to form a receiving layer.

  The thickness of the receiving layer formed as described above is arbitrary, but is generally 1 to 20 μm.

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

(Production of image receiving sheet)
An unstretched polypropylene film (Toyobo Co., Ltd. pyrene film-CTP1128; thickness: 30 μm) is bonded to urethane on an A-2 coat (thickness 165 μm) manufactured by Mitsubishi Paper Industries, Ltd. as a base sheet. The agent was dry laminated using a coating amount of 5 g / m ² and laminated.
Further, on the unstretched polypropylene film, a coating solution for forming a receiving layer having each composition shown in Table 1 was applied using a Mayer bar so as to have a coating amount of 5.0 g / m ² and then dried. Thus, a receiving layer was formed to prepare an image receiving sheet.
In Table 1, each name shown in the leftmost column means the following material or compound.
Byron 200: Saturated polyester resin manufactured by Toyobo Co., Ltd .;
Takenate D-110N: an isocyanate compound manufactured by Takeda Pharmaceutical Co., Ltd .;
PEG: polyethylene oxide manufactured by Sanyo Chemical Industries, Ltd. (numbers following PEG indicate molecular weight);
Melpol F-220: An isocyanate-modified product of polyethylene oxide manufactured by Sanyo Chemical Industries, Ltd., having a molecular weight of 100,000.
In Table 1, the compounding ratios of the polyester resin, polyethylene oxide, and isocyanate compound are adjusted so that the total of these three components is 100% in terms of the solid content ratio.
(Evaluation of image quality)
Each image-receiving sheet obtained in each example and each comparative example was cut into a size of 100 × 140 mm. A sublimation thermal transfer ribbon for the printer was set on a Sony sublimation thermal transfer printer CVP-G7, and 32 gradation gradation printing was performed on each of the image receiving sheets, and image quality unevenness was visually evaluated. The evaluation criteria were as follows. The results are shown in Table 2. In the evaluation, it is assumed that the region from the lighter density to the darker region is shifted from the first gradation to the 32nd gradation.
<Evaluation criteria>
A: There was no unevenness in all gradations.
○: There was some unevenness in the 1st to 2nd gradations, but there was no other gradation.
X: Unevenness was observed after 3 gradations.
(Silentness during printing)
Using the printer and the transfer ribbon, N = 10 people confirmed and evaluated the peeling sound when printing a black solid with yellow, magenta and cyan superimposed at the maximum energy. The evaluation criteria were as follows. The results are shown in Table 2.
<Evaluation criteria>
A: I felt that everyone was not interested.
○: I felt that 80% of the people were not worried.
X: I felt that more than 80% of people were interested.
(Print wrinkles, surface scratches)
The solid black portion printed in the above-described quietness test during printing was visually observed to evaluate printing wrinkles. The evaluation criteria were as follows. The results are shown in Table 3.
<Evaluation criteria>
○: A portion that could be judged as a print wrinkle was not observed.
X: Print wrinkles and portions that could be judged as surface scratches were observed.

Claims (3)

  A sublimation transfer image-receiving sheet provided with a receiving layer on a substrate, the receiving layer comprising at least one of a thermoplastic resin (A), a polyalkylene oxide and an isocyanate-modified product thereof (B), and an isocyanate compound ( A sublimation transfer image receiving sheet comprising C).   The sublimation transfer image-receiving sheet according to claim 1, wherein the polyalkylene oxide and the isocyanate-modified product (B) each have an average molecular weight of 20,000 to 2,000,000. The blending ratio of the components (A), (B) and (C) is such that at least one of polyalkylene oxide and its isocyanate-modified product (B) is 1 to 15 with respect to 100 parts by weight of the thermoplastic resin (A). The sublimation transfer image receiving sheet according to claim 1, wherein the weight part and the isocyanate compound (C) are 5 to 20 parts by weight.