JPH0462189A - Dye thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To provide the title sheet forming a dye image having high sensitivity and density, prevented from the heat fusion with an ink sheet, excellent in the preservability to heat and light and improved in the re-transfer preventing property of a printed image by using a specific copolymer and a crosslinking agent reacting therewith. CONSTITUTION:A dye thermal transfer image receiving sheet has a sheet-like support and the image receiving layer formed on one surface thereof and containing an isocyanate compound having two or more isocyanate groups and a vinyl chloride/vinyl acetate copolymer modified with a monomer having a functional group capable of reacting with the isocyanate groups of the isocyanate compound as main components. As the functional group reacting with isocyanate, one having active hydrogen is pref. The MW of the monomer modifying the vinyl chloride/vinyl acetate copolymer is pref. 2000 or more and the glass transition point thereof is pref. 40-80 deg.C. The use amount of the isocyanate compound ms pref. 20wt.% or less because the modified copolymer is hardened and the receptivity of a dye and sensitivity lower when said use amount is 20% or more by wt. of the image receiving layer.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a dye thermal transfer image-receiving sheet.

More specifically, the present invention dyes and receives a sublimable disperse dye image, and the received image has no heat fusion with the ink sheet, has high density, is clear, and has excellent needle origin and heat resistant storage stability. Moreover, the present invention relates to a dye thermal transfer image-receiving unit which prevents the printed image from being transferred to paper or the like even when it is stored in contact with paper or the like.

[Conventional technology]

Nowadays, the development of high-quality color hard copies using a thermal transfer recording method, especially printers using a dye thermal transfer method, is progressing rapidly. In the dye thermal transfer method, an ink sheet with sublimable dye layers of three colors (yellow, magenta, and cyan) is transferred by continuously controlling the heating energy of a thermal head to continuously transfer the amount of dye of each color. By changing the density, a full-color density gradation image can be printed on the image-receiving sheet.

In order to obtain a high-quality recorded image on the image-receiving sheet, it is necessary to use a dye that does not have thermal fusion properties with the ink sheet, has a high dye transfer speed and transfer dye amount, and has good storage stability against light and heat. A dyed layer is required.

In particular, the dye thermal transfer image-receiving sheet used in the dye thermal transfer recording method must have an image-receiving layer mainly composed of a thermoplastic resin that is easily dyed by the dye sublimated from the ink sheet. No. 3 discloses that an image-receiving sheet having an image-receiving layer containing a vinyl chloride resin, and in particular coexisting with a plasticizer, can have a high print density and less fading due to light. However, the image printed on the actual image receiving sheet is
In addition to print density, it is necessary to have excellent storage stability without discoloration, fading, or image bleeding due to heat or light. Furthermore, in order to produce an image-receiving sheet that is dyed with a dye, the image-receiving layer is formed from a resin solution dissolved in an appropriate organic solvent by a coating method such as a Mayer bar. , excellent solubility, or excellent dispersibility.

However, the vinyl chloride resin has problems such as insufficient solubility in solvents and bleeding in dye images when heated, and improvements have been desired.

For example, JP-A-63-51181 reports that an image-receiving layer containing a copolymer resin whose main monomer components are vinyl chloride and vinyl acetate has improved light resistance. has been done. However, even in this case, due to the shape of the thermal head, when the applied voltage and environmental temperature are high, further improvement in performance is desired to prevent thermal adhesion that occurs between the ink sheet and the image-receiving sheet. Ta. Furthermore, when stored in contact with paper, etc., the ability to prevent the transfer of printed images to paper, etc. is not fully satisfactory [a problem that Hakko is trying to solve]. The dye image thermally transferred from the ink sheet has high sensitivity and density, has no heat fusion with the ink sheet, has excellent storage stability against heat and light, and has the property of preventing retransfer of the printed image. An object of the present invention is to provide an improved dye thermal transfer image-receiving sheet.

[Means to solve the problem]

As a result of intensive research aimed at solving the above-mentioned problems, the present inventors discovered that the above-mentioned problems could be solved by using a special copolymer and a crosslinking agent that reacts with the copolymer. completed. The dye thermal transfer image-receiving sheet of the present invention comprises a sheet-like support, an isocyanate compound formed on at least one surface thereof and having two or more isocyanate groups, and a functional group capable of reacting with the isocyanate group of the isocyanate compound. an image-receiving layer containing as a main component a vinyl chloride-vinyl acetate copolymer (hereinafter referred to as vinyl chloride-vinyl acetate-modifying monomer copolymer) modified with a monomer having It is characterized by this.

The dye thermal transfer image-receiving sheet of the present invention has high printing sensitivity and dye density of the dye image thermally transferred from the ink sheet, does not have thermal fusion with the ink sheet, has excellent storage stability against heat and light, and has excellent printability. This is an improved method to prevent images from being transferred to paper, etc.

The sheet-like support used in the present invention includes high-quality paper, coated paper, polyester film, polyolefin and inorganic pigment as main components, and is uniaxial or biaxial, depending on the purpose.
Various plastic films such as synthetic paper made of an axially stretched film, or laminated sheets made of composites thereof can be used. The thickness of the sheet-like support used in the present invention is preferably 20 to 250 mm, and the basis weight is preferably 20 to 250 g/m'.

The vinyl chloride-vinyl acetate-modifying monomer copolymer used as the main component in the image-receiving layer of the present invention is produced by converting vinyl chloride, vinyl acetate, and the modifying monomer into radicals by heat, ultraviolet rays, or electron beams. It is produced by copolymerizing with a generated radical initiator, such as penzoinobenzophenone peroxide, by a suspension polymerization method, a bulk polymerization method, an emulsion polymerization method, or a homogeneous solution polymerization method.

In the polymerization, vinyl chloride, vinyl acetate, and a modifying monomer having a functional group that reacts with an isocyanate group are used as monomers. There are various functional groups that react with isocyanate, but among them, functional groups having active hydrogen are preferred. Such functional groups include hydroxyl group,
Carboxyl groups, amine groups, active methylene groups, etc. are preferred. Examples of the functional group-containing modifying monomer include hydroxyl group-containing acrylic acid esters, hydroxyl group-containing methacrylic esters, such as 2-hydroxyethyl acrylate, 2-(2-hydroxyethoxy)ethyl acrylate, and 2-hydroxycycloethyl acrylate. xyl acrylate, 2-
Hydroxy-2-phenylethyl acrylate, 2-hydroxybutyl acrylate, 4-hydroxybutyl acrylate, 2-hydroxypropyl acrylate, 3
-Hydroxypropyl acrylate, 2-hydroxy-
2-methylpropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate
Examples include root, 3-hydroxybutyl acrylate, and the like. Examples of amino group-containing monomers include vinylamines such as aminocarbonylmethyl acrylate, hinylethylamine, and vinylbenzylamine. Preferred examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, and maleic acid. Also,
After the polymerization reaction is completed, some of the ester groups of the polymer may be modified into hydroxyl groups.

Furthermore, along with the above modifying polymer, for example, a small amount of ester of acrylic acid or methacrylic acid, maleic acid and its estenobevinyl ether derivative, vinylidene chloride, acrylonitrile, methacrylonitrile, styrene, etc. may be added as necessary. It may be polymerized.

The ratio of each monomer used to synthesize the modified copolymer is 40 to 85% by weight of vinyl chloride, 5 to 40% by weight of vinyl acetate, and a monomer having a functional group that reacts with an isocyanate group. The amount of the modifying monomer is preferably 1 to 35% by weight, and the amount of monomers other than vinyl chloride, vinyl acetate, and the modifying monomer is preferably 5% by weight or less based on the total amount.

The vinyl chloride-vinyl acetate modifying monomer copolymer preferably has a molecular weight of 2,000 or more, and a glass transition point of 40 to 80°C.

When the vinyl chloride-vinyl acetate modifying monomer copolymer synthesized according to the present invention is used as an image-receiving layer component,
The vinyl chloride-vinyl acetate-modifying monomer copolymer may be used alone, or it may be mixed with other resins such as polyester resin, acrylic resin, polycarbonate resin, etc. good.

The isocyanate compound used together with the vinyl chloride-vinyl acetate-modifying monomer copolymer in the image-receiving layer of the present invention and which improves the heat resistance of the image-receiving layer by crosslinking with the copolymer is composed of two or more Polyfunctional isocyanate compounds having an isocyanate group, such as tolylene diisocyanate, triphenylmethane p,p'p"-)lisocyanate, and polymethylene polyisocyanate, are used.Amount of such isocyanate compound used If it exceeds 20% of the weight of the image-receiving layer, the resulting modified copolymer will be excessively hardened and the dye receptivity will decrease.
Since sensitivity decreases, the amount used is preferably 20% by weight or less, more preferably 10% by weight or less. However, if the amount used is less than 1% by weight, the modification effect will generally be insufficient.

Furthermore, in order to further improve the heat-resistant fusion properties between the ink ribbon and the image-receiving layer, the image-receiving layer contains paraffin, waxes such as polyethylene wax, metal soap, and silicone oinobeamino-modified silicone as release agents. , epoxy-modified silicone, alcohol-modified silicone, phosphate ester, etc. may be added, and the amount of these added is preferably 10% by weight or less.

When using vinyl chloride-vinyl acetate-modifying monomer copolymer as a component of the image-receiving layer, low-molecular organic compounds such as terpenes and substituted phenols are added for antioxidant, ultraviolet absorption, sensitization, etc. May be blended. A white pigment that is generally used to improve the whiteness and opacity of a paint, a fluorescent dye that adjusts the color tone of the receiving layer, and dyes such as blue and violet may be added.

It is convenient to apply additives such as the above-mentioned white pigment, ultraviolet absorber, and crosslinking agent by mixing them with the above-mentioned copolymer, which is the main component of the image-receiving layer. A separate coating layer may be applied above or below the image-receiving layer.

Generally, the thickness of the image-receiving layer is between 2 and 20 g/rn', preferably between 4 and 10 g/m'. If the thickness of the image-receiving layer is too small, the density and sensitivity of the image will be reduced and the uniformity of the image will be poor due to limitations in coating accuracy. Moreover, when the thickness is too large, the effect is saturated and not only is it uneconomical, but also the strength of the image-receiving layer is reduced.

In order to prevent the generation of static electricity when the image-receiving sheet runs in a printer, an antistatic agent must be applied to at least one surface of the sheet, added to the image-receiving layer, or contained by a method such as back coating. I can do it. Such a technique is not limited to thermal transfer, but is a well-known technique for printer paper. It is preferable to use a cationic polymer compound as the antistatic agent.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 Preparation of an ink sheet The following composition was coated on the back side of a No. 6 polyester film having a heat-resistant layer on one side using a Mayer bar so that the coating thickness after drying was 1 sl.

Disperse dye (Nippon Kayaku, 4 trademarks:
Kayaset Blue-136) Polyvinyl butyral resin, 6 (Made by Miki Kagaku, trademark: BM-3) Toluene 45 Methyl ethyl ketone 45 Formation of image-receiving layer Laminate 30-g polyethylene on both sides of high-quality paper with a basis weight of 64 g. Using this as a base material, on one side thereof, as an image-receiving layer of a sublimable dye, the following coating material-1 was applied at a coating amount of 5 g/m' in terms of solid content, and dried to form an image-receiving layer. An image receiving sheet for a dye thermal transfer printer was obtained.

Paint-1 Toluene 200
Methyl ethyl ketone 20
0 Dyeing property test The above ink sheet and image receiving sheet were brought into close contact, and the dye was thermally transferred from the ink sheet side to the receiving sheet using a dot density thermal head of 8 dots/dot under the conditions of applied power IW/dot and pulse width of 15 mm. did. Image density at this time,
The color tone was observed and evaluated with the naked eye.

Preservability test The preservability of thermal transfer images in the samples was tested under the following conditions.

Light resistance test: 50℃, 63%R using a xenon fade meter.
The samples were exposed for 48 hours under H conditions.

Heat resistance test The sample was stored in a blow dryer at 60°C for 100 hours. Changes in the image after the storage test under the above conditions were observed and evaluated with the naked eye.

Retransferability test The retransferability of the thermally transferred image was tested by bonding an electrophotographic copying paper with a printed receiving sheet and applying a load of 1 kg/cm.
It was stored at 30° C. for 48 hours at I[l], and its image transfer prevention properties were observed and evaluated.

Each evaluation was displayed on a 5-level scale.

5: excellent 4; good 3; general quality 2: poor 1; serious defects Example 2 The same operations as in Example 1 were carried out. However, the image-receiving layer of the image-receiving sheet was formed using the following paint-2.

Paint-2 toluene Methyl ethyl ketone The test results are shown in Table 1.

Example 3 The same operation as in Example 1 was performed. However, the following composition 2 was used as the ink composition for the ink sheet.

Margin Ink Composition-2: Polyvinyl butyral resin (manufactured by Miki Kagaku Co., Ltd., trademark: BM-3) Toluene 45 Methyl ethyl ketone 45 Also, the following paint-3 was used as a paint for the image-receiving layer of the image-receiving sheet.

Paint-3 toluene Methyl ethyl ketone The test results are shown in Table 1.

Comparative Example 1 The same operation as in Example 1 was performed. However, the following paint-4 was used as the paint for the image-receiving layer of the image-receiving sheet.

Paint-4 Completed toluene Methyl ethyl ketone The test results are shown in Table 1.

Comparative Example 2 The same operation as in Example 1 was performed. However, the following paint-4 was used as the paint for the image-receiving layer.

Paint-5 Ingredient parts by weight Comparative example 3 The same operation as in Example 1 was performed. However, the following paint 6 was used as the paint for the customer group.

Paint-6 Completed toluene Methyl ethyl ketone The test results are shown in Table 1.

Image reception Weight part Margin below toluene Methyl ethyl ketone The test results are shown in Table 1.

Table [Effects of the Invention] The dye thermal transfer image-receiving sheet of the present invention has a structure in which the image-receiving layer contains a modified vinyl chloride-vinyl acetate copolymer as a main component, thereby improving the sensitivity and dyeing of the transferred dye image. It has high density, is bright, does not discolor due to light or heat, and has high retransfer prevention properties, making it extremely practical.

Claims (1)

[Claims] 1. A sheet-like support, an isocyanate compound formed on at least one surface thereof and having two or more isocyanate groups, and modified with a monomer having a functional group capable of reacting with the isocyanate group of the isocyanate compound. 1. A dye thermal transfer image-receiving sheet comprising an image-receiving layer containing as a main component a vinyl chloride-vinyl acetate copolymer.