JPH02179792A - Dye thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To form a high quality image having high gloss and high dyeing concn. by forming an electron beam curable resin coating layer from electron beam curable silicone methacrylate and silicon acrylate compounds. CONSTITUTION:A coating layer composed of an electron beam curable resin being an org. compound material capable of being cured by the irradiation with electron beam is formed on the surface of a sheet like substrate. The org. compound material of this coating layer is composed of at least a compound selected from electron beam curable silicone methacrylate and silicon acrylate compounds. For example, as the silicon methacrylate compound, a compound represented by formula is used and a coating solution containing this compound is applied to the surface of synthetic paper by a bar coater. Subsequently, the coating layer is irradiated with electron beam to be cured and the resin coating layer dyed with a sublimable dye is formed to obtain a receiving sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field] The present invention relates to dye thermal transfer image receiving sheets. More specifically, the present invention provides an image-receiving sheet for a dye thermal transfer printer, which is capable of transferring and dyeing a sublimable dye by heat and receiving an image with excellent density and gloss with high sensitivity [Prior art] Among high-quality color hard copy printers that use a thermal transfer recording method, research on dye transfer printers has recently progressed rapidly. In the dye transfer method,
Using an ink sheet with sublimable dye layers of three colors (Y, M, and C), by continuously controlling the heat amount and heating time of the thermal head, the transfer amount of each color dye can be continuously controlled. , it is now possible to form full-color density gradation images.

Currently, image-receiving sheets for dye thermal transfer printers (hereinafter referred to as "receptor sheets") include
Those provided with a resin coating layer (image receiving N) mainly made of a polymer such as saturated copolymerized polyester that has high affinity with sublimable dyes are used. As a coloring mechanism in the dye transfer method, there is one coloring material,'' Vol. 59 (10), p. 607 (19
86), when a polyester resin coating layer with a relatively low glass transition temperature undergoes intense molecular movement in the polymer chains of the amorphous region in that area by local heating, it melts and softens, becoming viscous. It becomes a liquid with a certain amount.

Next, the dye particles sublimated by the transfer operation fly in, become embedded in the amorphous region by cooling, dye the polyester resin coating layer, and form a colored image. This dye transfer method requires a large amount of energy to sublimate the dye, and therefore has the disadvantage of slow transfer speed. In order to improve this transfer speed, attempts have been made to lower the glass transition temperature of the resin used for the resin coating layer of the receiving sheet. However, in this case, the surface of the resin coating layer becomes rough due to heating during printing, resulting in a problem in that the gloss of the transferred image decreases. In even more severe cases, the resin coating layer on the receiving sheet may completely melt during printing, causing problems such as the receiving sheet adhering to the ink sheet and blocking occurring when the two are peeled off.

In order to solve the above problems, Japanese Patent Application Laid-Open No. 173295/1986
proposes applying a coating liquid consisting of a radically polymerizable oligomer and/or monomer that is cured by radiation onto the surface of a sheet-like substrate, and then curing it with an electron beam. This method yields a resin coating layer with high crosslinking density;
Although adhesion between the receiving sheet and the ink sheet can be prevented, due to the high crosslinking density of the resin coating layer, the resin coating layer does not melt and soften into a viscous liquid during printing, and therefore the dye image on the resin coating layer does not melt and soften. This poses a problem in that the receptivity decreases and it is difficult to obtain high-density images.

- Polyester acrylates, urethane acrylates, epoxy acrylates, and the like having at least one acryloyl group in one molecule are used as electron beam-curable organic compounds. When these compounds are irradiated with electron beams, active species are generated in the compounds and a network polymer is instantly formed. These network polymers have excellent heat resistance, abrasion resistance, and high gloss, and when applied to form a resin coating layer on a receiving sheet, blocking occurs between the resin coating layer and the ink sheet during printing. There are no words to say. However, since the molecular chains of this electron beam-cured network polymer are highly crosslinked, their movement is suppressed even at high temperatures, and therefore they do not melt and soften to form a viscous liquid. Therefore, there is a problem in that the dye sublimated from the ink sheet is difficult to permeate into the network polymer layer, and therefore only images with low dye density can be obtained. In addition, when improving the dyeability of thermally transferred dye images on network polymers with a reduced amount of crosslinking, the heat resistance of the resin coating layer deteriorates, resulting in various problems such as a decrease in gloss and the formation of blocking with the ink sheet. It was arousing.

[Problem to be solved by the invention]

The present invention solves the above-mentioned drawbacks of conventional dye thermal transfer image-receiving sheets, such as decreased dye image receptivity when highly cross-linked and low heat resistance when low-cross-linked, and improves sensitivity. It is an object of the present invention to provide a dye thermal transfer image-receiving sheet capable of receiving images with high color density, high density, and gloss.

[Means to solve the problem]

The dye thermal transfer image-receiving sheet of the present invention includes a sheet-like substrate and an electron beam-curable resin coating layer formed on at least one surface of the sheet-like substrate and made of an organic compound material that can be cured by electron beam irradiation. The organic compound material is composed of at least one member selected from electron beam curable silicon methacrylate and silicon acrylate compounds.As a result of examining the dyeability and heat resistance of the acrylic compound, it was found that the organic compound material is electron beam curable by electron beam irradiation. The main chain of the curable organic compound is -(Si-0).

(R is hydrogen or a methyl group, n is an integer of 2 or more)
By using a silicon-based electron beam curable compound consisting of repeating units represented by the formula and having an acryloyl group or a methacryloyl group at at least one end of the main chain for forming the resin coating layer, it is possible to form a thermal transfer dye image. The present invention was completed based on the discovery that a receiving sheet with high receiving sensitivity and capable of forming dye images with high density and gloss can be obtained.

The reasons why the above-mentioned silicone-based electron beam curable resin exhibits excellent performance as a resin coating layer for receiving sheets are as follows: (1) The siloxane polymer main chain of the skeleton has a fairly low glass transition temperature; The dye sublimated from the surface easily bleeds through.

(2) The double bond group in the acryloyl group and/or methacryloyl group undergoes ring-opening crosslinking by electron beam irradiation to cause a curing reaction, but the surface energy of the silicone polymer main chain
Since it is lower than other polymers, even if the crosslinking density is low, adhesion between the resin coating layer and the ink sheet will not occur.

(3) It is an ester compound like the polyester resin commonly used in the resin coating layer of the receptor sheet, and has good affinity for dyes.

As the silicon-based electron beam curable organic compound in the present invention, the following compounds can be exemplified.

(1) A reaction product of dimethylpolysiloxane, T-methacryloprobyltrimethoxysilane and hexyl alcohol. Its specific structure is shown in formula (1).

(2) Dimethylpolysiloxane, 2,4-toluene diisocyanate and 2-hydroxyethyl methacrylate or a reaction product of 2-hydroxyethyl acrylate. Its specific structure is shown in formula (2).

It is shown in equation (3).

C.I.

[However, in the above formula (3), A3 is the following formula: [However, in the above formula (2), A1 is the following formula: -CHzCHzOOCC=
(3) dimethylpolysiloxane, 4,4-methylene diphenyl diisocyanate and 2-hydroxyethyl methacrylate, n represents an integer of 8 or more, R represents a methyl group or a hydrogen atom) - reaction product of hydroxyethyl acrylate. Its specific structure is -CHzCHz00CC
=CHz represents an unsaturated group, n represents an integer of 8 or more, and R represents a methyl group or a hydrogen atom).

Examples of the sheet-like substrate in the receiving sheet of the present invention include wood-free paper, coated paper, and synthetic paper made from biaxially stretched film containing polyolefin and inorganic pigment as main components.
Various plastic films or a laminated sheet made of a combination thereof can be used. There are no particular limitations on the thickness or basis weight of this sheet-like substrate, but the thickness is generally 20
-250 g/rT'r, and the basis weight is preferably 20-250 g/rT'r.

In the receptor sheet of the present invention, the resin coating layer is formed by applying a coating containing the above-mentioned electron beam-curable silicone compound to the surface of the sheet-like substrate, and curing the coating by irradiating it with an electron beam. be done. Examples of methods for applying an electron beam curable paint to a sheet-like substrate include methods using bar codes, air doctor coatings, blade coatings, squeeze coatings, air knife coatings, reverse roll coatings, transfer coatings, and the like. It is preferable to set the thickness of this much-anticipated paint coating layer so that the resin coating layer obtained by electron beam curing has a thickness of 2 to 20 μm. If the thickness is less than 2p, the density and reception sensitivity of the resulting image will be reduced, and the uniformity of the image may be reduced due to limitations in coating accuracy. Also, this thickness is 2
Even if it is thicker than 0-, the density and sensitivity of the image will be saturated and it will be uneconomical.

Generally, it is preferable that the weight of the resin coating layer is -~''g/a.

As the electron beam accelerator used for electron beam curing, a curtain beam type accelerator that is relatively inexpensive and can provide a large output can be used. In electron beam irradiation using this curtain beam method, there are no particular restrictions on accelerating voltage or absorbed dose, but generally the accelerating voltage is 100 to 300 Kv,
Preferably, the absorbed dose is between 0.5 and 10 Flrad. Further, the oxygen concentration in the irradiation atmosphere is preferably 500 ppm or less; if it is higher than 500 ppm, oxygen may act as a polymerization retardant, resulting in insufficient curing.

〔Example〕

The present invention will be described in detail below with reference to Examples, but the scope of the present invention is not limited thereby.

Actual grade 1t1 A silicon methacrylate compound having the chemical structure of the following formula: H3 A coating liquid consisting of H3 A2-CHzCHz00CC=CHz was placed on one side of synthetic paper (manufactured by Tamago Oil Chemical Synthetic Paper) having a thickness of 1501 M using a bar. With the coater, the amount of coating after curing is L.
Then, the coating layer was cured by irradiating the coating layer with an electron beam at an absorbed dose of 5 Mrad, and a resin coating layer dyed with a sublimable dye was formed. Formed.

The obtained receiving sheet was subjected to the following printing process.

That is, dye thermal transfer printer (trademark: VY-20,
Using a color par signal generator (Trademark:
A step pattern supplied by C13A2 (manufactured by Shibazoku Co., Ltd.) was printed on the resin coating layer of the receiving sheet (YELLOW, MAGENTA).

CYANN superimposed black print). Table 1 shows the 60 degree glossiness of the blank area of the obtained receiving sheet, the 60 degree glossiness of the printed area, and the 10th gradation density of the step pattern.

Glossiness is measured using a gloss meter (trademark: Gloss Meter)
GJl-260,.

Nurakami Research Laboratory
The print density was measured using a Macbeth densitometer (trademark: RD-914, Kollmorgen C).
The measurement was performed using a microcomputer (manufactured by ARP).

(Method for producing the silicon methacrylate) Toluene diisocyanate was added to polydimethylsiloxane so that the NCO:OH molar ratio was 2:1, and under a nitrogen atmosphere,
Both were mixed by stirring at 25°C. After 2 hours, the temperature was raised to 60''C, and toluene diisocyanate and equimolar amounts of hydroxyethyl methacrylate were added to the mixture, followed by further stirring and mixing for 5 hours. The above-mentioned silicon methacrylate was produced.

``Example 1'' The same operations as in Example 1 were performed. However, a resin coating layer dyed with a sublimable dye was prepared using a crude solution f consisting of the following silicon acrylate compound.

The mixture was further stirred and mixed for 5 hours to obtain the above silicon acrylate.

The same operation as in Example 1 was carried out. However, a resin coating layer dyed with a sublimable dye was prepared using the following silicon methacrylate compound.

A”=-CH2C)!!0OCC=CHz 0OCC=
60 degree gloss of the blank part of the CHZ sheet, 6 of the printed part
It shows the 0 degree gloss level and the 10th level cleaning density of Ste Knob pattern.

(Method for producing the above silicone acrylate compound) 1,6-hexane diisocyanate is added to polydimethylsiloxane so that the NCO:OH molar ratio is 2=1,
The mixture was stirred and mixed at 25°C under a nitrogen atmosphere. After 2 hours, the temperature of the mixture was brought to 60°C, and to this was added hydroxyethyl acrylate in an equimolar amount of 16-hexane diisocyanate and CH.

AI±-C-CH2 (Production method of the above silicone methacrylate compound) Dimethylpolysiloxane, T-methacryloxypropyltrimethoxysilane, and hexyl alcohol (molar ratio is 1
:2.1:0.1) were reacted at 150°C for 6 hours to obtain the above silicon methacrylate compound.

Table 1 shows the 60 degree gloss of the blank area of the receiving sheet, the 60 degree gloss of the print area, and the density of the 10th floor and the 8th turn of the step pattern.

Art] The same operations as in Example 1 were performed. However, the resin coating layer dyed with a sublimable dye was prepared using a mixture of 50 parts by weight of the silicone methacrylate compound used in Example 1 and 50 parts by weight of the silicone acrylate compound used in Example 2. 6 of the blank section of the receiving sheet obtained in Table 1
It shows the 0 degree glossiness, the 60 degree glossiness of the printed part, and the 10th gradation density of the step pattern.

The same operation as in Example I was carried out on one school spot. However, the resin coating layer dyed with a sublimable dye was prepared using the following mixture of electron beam curable acrylic compounds.

Epoxy acrylate 50 parts by weight (trademark;
Visco-1-540, Osaka Organic Chemical Group, the following structural formula (a
) A'=-COCH=CHz Formula (a) (Trademark: Kayarad R-551, manufactured by Nippon Kayaku, compound of the following structural formula (b)) A4-COCR=CHz Formula (b) (
In formula (b), both m+n are integers of 1 or more, and m
+n=4) Table 1 shows the 60 degree gloss of the blank area of the obtained receiving sheet, the 60 degree gloss of the printed area, and the density of the 10th gradation of the step pattern.

Stop comparison fl The same operation as in Example 1 was performed. However, as the layer dyed with the sublimation dye, a dye thermal transfer printer (manufactured by Toru-Nakayoeki 1γ) was used. Table 1 shows the 60 degree gloss of the blank area of the obtained receiving sheet, the 60 degree gloss of the print area, and the density of the 10th floor and the 8th step pattern.

Table-1 hand Continued Supplementary Positive book (spontaneous) February 1999 77 days

Claims (1)

[Scope of Claims] 1. A sheet-like substrate, and a coating layer formed on at least one surface of the sheet-like substrate and made of an electron beam-curable resin of an organic compound material that can be cured by electron beam irradiation. A dye thermal transfer image-receiving sheet comprising: the organic compound material comprising at least one member selected from an electron beam curable silicone methacrylate compound and a silicone acrylate compound.