JPH04316890A - Thermally transferred dye image receiving sheet - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

FIELD OF THE INVENTION This invention relates to dye thermal transfer image-receiving sheets. More specifically, the present invention relates to a dye thermal transfer image-receiving sheet that is capable of transferring and dyeing a sublimable dye by heat and receiving a colored image with excellent density and gloss with high sensitivity.

0002

2. Description of the Related Art Among high-quality color hard copies using a thermal transfer recording method, research is progressing on printers using a dye transfer method. In the dye transfer method, the amount of dye transferred for each color is continuously controlled by the amount of heat and heating time of a thermal head that continuously controls the ink sheet of three colors (yellow, magenta, cyan) that has a sublimable dye layer. death,
It is now possible to form full-color density gradation images.

Currently, receiving sheets for dye thermal transfer printers (hereinafter referred to as image receiving sheets) have resin coating layers mainly made of polymers such as saturated copolymer polyesters and salt-vinyl acetate resins that have high affinity with sublimable dyes. (hereinafter referred to as an image-receiving layer) is used. The color development mechanism of the dye transfer method is described in “Color Materials, 59 (10), 1986 p607.
”, a polyester image-receiving layer with a relatively low glass transition temperature can be heated by localized heating.
Vigorous molecular motion occurs in the polymer chains in the amorphous region of that part, which melts and softens it into a viscous liquid. Next, the dye sublimated by the transfer operation flies in, and upon cooling, the dye molecules become embedded in the amorphous region, dyeing the image-receiving layer and forming a colored image. Images printed using this dye transfer method have the disadvantage that there is a lot of density unevenness and the image has poor storage stability. In order to solve this problem, attempts have been made to make the surface of the image-receiving layer highly smooth to improve its adhesion to the ink sheet and improve printing speed and image quality. For example, JP-A-62
No. 211195 proposes applying a water-based paint to a base material by a casting method to provide a highly smooth image-receiving layer. Although this method yields a highly glossy image-receiving layer, When drying the image-receiving layer, water is evaporated on the cast drum, creating pores on the surface and inner surface of the image-receiving layer due to water evaporation, making it impossible to obtain a truly smooth and uniform receptive layer. Therefore, there is a problem in that the printed image has many density irregularities.

[0004] Also, in Japanese Patent Application Laid-open No. 173295/1986,
It has been proposed that a coating liquid consisting of a radically polymerizable oligomer or monomer that is cured by radiation is applied to a sheet-like substrate and then cured by an electron beam. Although an image-receiving layer with high gloss can be obtained by this method, due to the high crosslinking density of the image-receiving layer obtained, the image-receiving layer does not melt and soften into a viscous liquid during the thermal transfer process. This poses a problem in that the dyeability of the layer is poor and it is difficult to obtain high-density images.

[0005]

[Problems to be Solved by the Invention] The present invention solves the above-mentioned drawbacks of the conventional technology, and provides an image-receiving layer with a smooth surface, no bubbles or voids inside, and an image-receiving layer that is cured with active energy rays. The present invention aims to improve the drawbacks of image-receiving layers obtained from radically polymerizable oligomers or monomers, namely low image density, and to provide a dye thermal transfer image-receiving sheet having an image-receiving layer that is free from density unevenness and has excellent image storage stability. It is something to do.

[0006]

[Means for Solving the Problems] When forming a dye-receptive resin by an active energy ray irradiation curing reaction, the present inventors used (a) acrylic acid or methacrylic acid as a resin precursor material. The present invention has been completed by discovering that the above problems can be solved by using a reaction product with an aromatic glycidyl compound having a chemical structure and a reaction product with (b) a polyvalent isocyanate compound.

The dye thermal transfer image-receiving sheet of the present invention comprises a sheet-like support and an active energy ray irradiation cured product of a resin precursor material formed on at least one surface thereof and curable by active energy ray irradiation. an image-receiving layer containing a dye-receiving resin as a main component;
The active energy ray irradiation curable resin precursor material for forming a dye-receptive resin comprises (a) the following reaction components (i) and (ii); (i) at least one selected from acrylic acid and methacrylic acid;
a reaction component consisting of a species, and (ii) the following general formula (I)
;

A reaction product of a reaction component consisting of at least one aromatic glycidyl compound represented by: (b) at least one polyvalent isocyanate compound;
It is characterized by containing a reaction product of.

[0008]

[Operation] In the present invention, the reaction component (i) consisting of the above acrylic acid and/or methacrylic acid and the general formula (
Reaction component (ii) consisting of an aromatic glycidyl compound of I)
) and a reaction product of a polyvalent isocyanate compound (b). This method solves the problems mentioned above in the prior art, and has excellent transfer sensitivity to dyes, high color density of the resulting colored image, and excellent storage durability against heat and light.

Common active energy ray-curable resin precursor compounds include polyester acrylates, urethane acrylates, and epoxy acrylates having at least one acryloyl group in one molecule. When these compounds are irradiated with electron beams, active species are generated in the compounds, which are instantly polymerized and cured to form network polymers with excellent heat resistance, body abrasion resistance, and high gloss. When these network polymers are applied to image-receiving layers,
Because the molecular chains of network polymers are highly cross-linked, their motion is controlled even at high temperatures, so they do not melt and soften to form a viscous liquid. Therefore, the dye sublimated from the ink sheet is difficult to penetrate into the network polymer layer, resulting in a disadvantage that the color density of the obtained dye image is low. In addition, if the crosslinking of the cured resin is controlled to improve the dye adhesion into the network polymer layer, the heat resistance of the resulting image-receiving layer will deteriorate, resulting in lower image gloss and blocking with the ink sheet. It was causing problems.

The reason why the active energy ray-curable resin of the present invention exhibits high dye receptivity is not fully clear, but it is presumed as follows. That is, conventional polyester resins and aromatic active energy ray-curable resins have aromatic rings incorporated into the polymer main chain, but the resin of the present invention has an acrylic group as the main chain and is derived from an aromatic glycidyl compound. It is thought that the aromatic cyclic structure is branched. It is presumed that the polymer structure having such characteristics increases the diffusivity of the dye, thereby increasing the dyeing property and further contributing to the improvement of weather resistance. Furthermore, the active energy ray-curable resin precursor compound of the present invention can be used as a solvent-free coating material in the same way as ordinary active energy ray-curable resin precursor compounds, and there is no evaporation of the solvent in the curing process. The resulting cured resin layer does not contain pores or voids, and therefore an image-receiving layer having an extremely homogeneous structure can be obtained.

The active energy ray-curable resin precursor compound of the present invention comprises (meth)acrylic acid (i) and general formula (I).
A reaction product (hereinafter referred to as component (a)) with aromatic glycidyl compound (ii) and a polyvalent isocyanate compound (
(hereinafter referred to as component (b)).

The component (a) has the general formula (III):

[
It contains at least one compound represented by the following formula.

Specific examples of the aromatic glycidyl compound of general formula (I) include phenyl glycidyl ether, p-t
ert-butylphenyl glycidyl ether, p-α-
Examples include cumylphenyl glycidyl ether, p-tert-butylphenyl glycidyl ester, glycidyl phthalimide, α-naphthyl glycidyl ether, β-naphthyl glycidyl ether, and triphenylmethyl glycidyl ether.

The component (b) consists of at least one polyvalent isocyanate compound, and any conventionally known compound can be used as is. Specific examples of such polyvalent isocyanate compounds include diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, phenylene diisocyanate, and tolylene diisocyanate.

Next, the method for producing the resin precursor compound of the present invention will be explained. (a) component compound is a reaction component (i) consisting of acrylic acid and/or methacrylic acid;
It is obtained by carrying out an esterification reaction with the reaction component (ii) consisting of an aromatic glycidyl compound. For example, phenoxyglycidyl ether (5.81 mol) and acrylic acid (
5.81 mol), benzyltrimethylammonium bromide (1000 ppm) as an esterification catalyst,
A mixture of 4-methoxyphenol and phenithiazine as a polymerization inhibitor was charged into a reaction vessel and reacted at 105 to 110°C for 6 hours under a nitrogen stream to obtain (a)
ingredients can be obtained.

The component (a) thus obtained is converted into (b)
A resin precursor compound can be obtained by compounding and reacting the components in the following manner. That is, component (a) and component (b) consisting of a polyvalent isocyanate compound are charged into a reaction vessel, and both components are reacted. Component (a) and component (b)
The charging molar ratio of component (a) to the isocyanate group is
: Isocyanate group of component (b) = 1.0 to 4.0:1
．． 0, and preferably the ratio of component (a) to isocyanate group of component (b) is 1.6 to 3.0:1.0.

It is preferable to add a trace amount of stannous octylate as a catalyst for the reaction between the isocyanate group of the compound of component (b) and the hydroxyl group of the compound of component (a), and also to add a trace amount of stannous octylate. In order to suppress the reaction of acrylic polymerization, it is preferable to add a polymerization inhibitor such as 4-methoxyphenol or phenithiazine. If the viscosity of the reaction system becomes excessively high during the reaction, add a diluent consisting of a compound without active hydrogen, such as toluene, or a reactive diluent such as hexamethylene diacrylate, to reduce the viscosity of the reaction system. It is also possible to reduce the viscosity of Generally, the reaction between component (a) and component (b) is 40 to 1
It is completed in 2 to 10 hours at 20°C.

[0018] In preparing the resin precursor coating material used in the present invention, in order to adjust the viscosity, a viscosity adjusting agent comprising at least one selected from alkyl acrylamide and monofunctional acrylate and methacrylate compounds is used. Additives may be added to the resin precursor material.

As the (meth)acrylate compound used in such a viscosity modifier, isopropyl (meth)
acrylate, isobutyl (meth)acrylate, t-
Butyl (meth)acrylate, cyclohexyl (meth)
Acrylate, β-hydroxyethyl acrylate, polyethylene glycol (meth)acrylate, β-hydroxypropyl (meth)acrylate, 2-cyanoethyl (meth)acrylate, benzoyloxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, ) acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and the like. Furthermore, since using only a (meth)acrylate monomer may lower the Tg of the resulting image-receiving layer, it is preferable to add an amide monomer such as dimethylacrylamide. The amount of such a viscosity modifier is preferably 10 to 50% based on the weight of the resin precursor material.

The resin precursor material in the present invention contains 2% to 15% by weight of a silicon compound that can be cured by active energy rays.
It may be blended in weight%. If the amount is less than 2% by weight, blocking with the ink sheet may occur during printing, and if it exceeds 15% by weight, the effect of improving peeling and blocking will be saturated, so even if more than 2% is added. It becomes disadvantageous in terms of cost.

[0021] Low-molecular organic compounds such as substituted phenols and terpenes can be blended into the image-receiving layer of the present invention for the purpose of antioxidant, ultraviolet absorption, sensitization, etc.
In addition, white pigments are generally used to improve the whiteness and opacity of paints, fluorescent dyes are used to adjust the color tone of image-receiving layers,
Dyes such as blue and violet can also be added as necessary. It is convenient to apply the above additives such as white pigments and ultraviolet absorbers by mixing them with the resin precursor material of the present invention. It may be coated underneath.

[0022] In order to prevent static electricity from being generated when the image-receiving sheet runs in a printer and causing running troubles, an antistatic agent is added to the image-receiving layer formed on at least one surface of the image-receiving sheet. or it may be applied as a subbing layer, backcoat, etc. below the image-receiving layer or on the back side of the sheet support.

The resin precursor material of the present invention is mixed with the above-mentioned additives and applied as a coating onto a sheet-like support, and this coating layer is cured by active energy rays such as electron beams and ultraviolet rays. When using an electron beam as an active energy beam, a curtain beam type electron beam accelerator can be used, which is relatively inexpensive and can provide a large output. In this curtain beam method, the acceleration voltage is 100 to 3
00 Kv and the absorbed dose is preferably 0.5 to 10 Mrad. Further, the oxygen concentration in the irradiation atmosphere is preferably 500 ppm or less. Oxygen concentration in the irradiation atmosphere is 500 ppm
If it is larger, oxygen may act as a polymerization retarder, resulting in insufficient curing.

When ultraviolet rays are used as active energy rays, a photoinitiator is added in an amount of 0.1 to 10% by weight based on the total amount of the image-receiving layer coating solution. Specific examples of the photoinitiator include benzoin ether compounds, mixtures of benzophenone compounds and amine compounds, mixtures of thioxanthone compounds and amine compounds, acetophenone compounds, ketal compounds, and the like.

[0025] Examples of the sheet-like substrate used in the present invention include wood-free paper, coated paper, various plastic films such as synthetic paper such as biaxially stretched film containing polyolefin and inorganic pigment as main components, and laminated sheets made of a combination thereof. can be used. The thickness of the support used in the present invention is 20 to 250 μm, and the basis weight is 20 to 250 g/m.
It is preferable that it is 2.

[0026] Examples of methods for applying the coating composition to the sheet-like substrate include methods using bar coating, air doctor coating, blade coating, squeeze coating, air knife coating, reverse roll coating, transfer coating, etc. . Alternatively, after applying the coating material to the base material by the above-mentioned coating method, the coating liquid layer may be pressed onto a cast drum, and radiation may be irradiated thereon through the sheet-like support. The thickness of the coating layer obtained at this time is preferably 2 to 20 μm after electron beam curing. If the thickness is less than 2 μm, the density and sensitivity of the image will decrease, and there will be a limit to coating accuracy, resulting in poor uniformity of the image obtained. Moreover, if the thickness exceeds 20 μm, the color density and sensitivity of the image will become saturated, which is uneconomical.

[0027]

EXAMPLES The present invention will be explained in detail with reference to Examples below, but the present invention is not limited thereto.

Synthesis Example 1 Synthesis of Resin A Component (a) and component (b) listed below were reacted at 75 to 80° C. for 7 hours to obtain resin precursor material A. Component (a): Acrylic acid ester compound of phenyl glycidyl ether Component (b): Isophorone diisocyanate

[0029]
Synthesis Example 2 Synthesis of Resin B Component (a) and component (b) listed below were reacted at 75 to 80° C. for 7 hours to obtain resin precursor material B. Component (a): Acrylic acid ester compound of p-tert-butylphenyl glycidyl ether Component (b): Isophorone diisocyanate

[0030]
Synthesis Example 3 Synthesis of Resin C Component (a) and component (b) listed below were reacted at 75 to 80° C. for 7 hours to obtain resin precursor material C. Component (a): Acrylic acid ester compound of o-phenylphenoxyglycidyl ether Component (b): Isophorone diisocyanate

[0031]
Synthesis Example 4 Synthesis of Resin D Component (a) and component (b) listed below were reacted at 75 to 80° C. for 7 hours to obtain resin precursor material D. Component (a): A mixture of an acrylic ester compound of phenyl glycidyl ether and an acrylic ester compound of p-tert-butylphenyl glycidyl ether (molar ratio 1/1) Component (b): Isophorone diisocyanate

[0032]
Synthesis Example 5 Synthesis of Resin E Component (a) and component (b) listed below were reacted at 75 to 80° C. for 7 hours to obtain resin precursor material E. Component (a): Acrylic acid ester compound of phenyl glycidyl ether Component (b): Trifunctional isocyanate compound (trademark: Coronate HX, manufactured by Nippon Polyurethane Co., Ltd.)

Synthesis Example 6 Synthesis of Resin F Component (a) and component (b) listed below were reacted at 75 to 80° C. for 7 hours to obtain resin precursor E. Component (a): Acrylic acid ester compound of p-cumylphenyl glycidyl ether Component (b): Isophorone diisocyanate

[0034]
Synthesis Example 7 Synthesis of Resin G Component (a) and component (b) listed below were reacted at 75 to 80° C. for 7 hours to obtain resin precursor F. Component (a): Acrylic ester compound of aliphatic glycidyl ether (2-ethylhexyl glycidyl ether) Component (b): Isophorone diisocyanate

[0035]
Example 1 An image receiving sheet was prepared by the following steps. Formation of image-receiving layer A 150 g/m2 high-quality paper laminated with 30 μm polyethylene on both sides was used as a base material, and a paint having the following composition was applied on one side of the base material, with a dry solid content of 10 g/m2.
It was coated so that it became 2. Next, a polyethylene terephthalate (PET) film (trademark: Lumirror, manufactured by Toray) with a thickness of 50 μm is pressure-bonded onto this coating liquid layer.
A 4Mr electron beam is passed through the back side of the ET film.
The coating liquid layer was cured by irradiation to obtain an absorbed dose of ad. After curing, the PET film was peeled off from the resulting image-receiving layer to obtain a dye thermal transfer image-receiving sheet.

Resin precursor material A of composition synthesis example 1 of paint for image-receiving layer
80 parts by weight silicone (trademark: EBECRYL 350
, 5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
5 parts by weight

Performance test The dye thermal transfer image receiving sheet obtained as described above was coated with a sublimation thermal transfer color printer (Hitachi VY-P1).
) was used to print a test pattern. The resulting prints were evaluated for the sensitivity of the image-receiving layer during printing, the maximum density of the image, the light resistance of the image, and the image quality. The evaluation results were evaluated in five stages as shown below. Excellent...5 Good...4 Average...3 Slightly poor...2 Poor...1 In addition, in the sensitivity test, we compared the image transfer density at low energy. The color density was measured using a Macbeth densitometer. The light resistance of the image was determined by observing changes in image density and color tone after 50-hour irradiation treatment at 50° C. and 63% RH using a fade meter using a xenon light source. The evaluation results are shown in Table-1.

Example 2 The same operation as in Example 1 was carried out. However, the paint for the image-receiving layer used had the following composition. Resin precursor material B of composition synthesis example 2 of paint for image-receiving layer
80 parts by weight silicone (trademark: EBECRYL 350
, 5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
Table 1 shows the evaluation results for 5 parts by weight.

Example 3 The same operation as in Example 1 was carried out. However, the paint for the image-receiving layer used had the following composition. Resin precursor material C of composition synthesis example 3 of paint for image-receiving layer
80 parts by weight silicone (trademark: EBECRYL 350
, 5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
Table 1 shows the evaluation results for 5 parts by weight.

Example 4 The same operation as in Example 1 was carried out. However, the paint for the image-receiving layer used had the following composition. Resin precursor material D of composition synthesis example 4 of paint for image-receiving layer
80 parts by weight silicone (trademark: EBECRYL 350
, 5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
Table 1 shows the evaluation results for 5 parts by weight.

Example 5 The same operation as in Example 1 was carried out. However, the paint for the image-receiving layer used had the following composition. Resin precursor material E of composition synthesis example 5 of paint for image-receiving layer
80 parts by weight silicone (trademark: EBECRYL 350
, 5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
Table 1 shows the evaluation results for 5 parts by weight.

Example 6 The same operation as in Example 1 was carried out. However, the paint for the image-receiving layer used had the following composition. Resin precursor material F of composition synthesis example 6 of paint for image-receiving layer
80 parts by weight silicone (trademark: EBECRYL 350
, 5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
Table 1 shows the evaluation results for 5 parts by weight.

Comparative Example 1 The same operation as in Example 1 was carried out. However, the paint for the image-receiving layer used had the following composition. Resin precursor material G of composition synthesis example 7 of paint for image-receiving layer
80 parts by weight silicone (trademark: EBECRYL 350
, 5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
Table 1 shows the evaluation results for 5 parts by weight.

Comparative Example 2 The same operation as in Example 1 was carried out. However, the paint for the image-receiving layer used had the following composition. Composition of paint for image-receiving layer: Unsaturated acrylic compound
80 parts by weight (Trademark: Viscoat 540, manufactured by Osaka Organic Chemical Industry) Silicone (Trademark: EBECRYL 350,
5 parts by weight (Manufactured by Daicel UCB) Dimethylacrylamide
15 parts by weight hexadiol diacrylate
Table 1 shows the evaluation results for 5 parts by weight.

Comparative Example 3 A 150 g/m2 high-quality paper screen laminated with polyethylene of 30 μm each was used as a base material, and a paint having the following composition was applied on one side to a solid content of 10 g/m2. The dye thermal transfer image receiving sheet was obtained by processing and drying. Hereinafter, the same operations as in Example 1 were performed. Composition of paint for image-receiving layer Commercially available polyester resin
100 parts by weight (trademark: Byron 290, manufactured by Toyobo) Silicone (trademark: SH3476,
Toluene
200 parts by weight Methyl ethyl ketone 200 parts by weight The evaluation results are shown in Table-1.

[Table 1]

[0046]

[Effects of the Invention] The dye thermal transfer image receiving sheet of the present invention has
By using a reaction product of (meth)acrylic acid, an aromatic glycidyl compound, and a polyvalent isocyanate in the image-receiving layer, the thermally transferred image has high color density, high durability against light, and excellent image quality. It is a material that is practically useful as an image-receiving sheet for dye thermal transfer printers.

Claims (1)

[Claims] Claim 1: A sheet-like support, and at least one thereof.
an image-receiving layer formed on the surface and containing as a main component a dye-receptive resin made of an active-energy-ray irradiation-cured product of a resin precursor material that can be cured by active-energy ray irradiation; The active energy ray irradiation curable resin precursor material for forming a synthetic resin comprises (a) the following reaction components (i) and (ii); (i) at least one selected from acrylic acid and methacrylic acid;
a reaction component consisting of a species, and (ii) the following general formula (I)
; with a reaction product of a reaction component consisting of at least one aromatic glycidyl compound represented by the following formula; (b) with at least one polyvalent isocyanate compound;
1. A dye thermal transfer image-receiving sheet comprising a reaction product of: