JPH02198894A - Thermal transfer image receiving material - Google Patents

Abstract

PURPOSE:To improve the close adhesiveness of a dyeable resin layer and a laminate layer and to reduce curling before and after printing by forming the first laminate layer from a modified polyolefin resin and applying surface oxidation treatment thereto and forming the second laminate layer from a resin whose thermal deformation properties are lower than those of the resin of the first laminate layer. CONSTITUTION:Image receiving paper consists of an image receiving paper base material 10 and a dyeable resin layer 3. The image receiving paper base material 10 has a three-layered structure consisting of a core material 1, the first laminate layer 2 and the second laminate layer 2' and surface oxidation treatment is applied to the first laminate layer. A highly adhesive modified polyolefin resin is used in the first laminate layer on the side of the dyeable resin layer and, concretely, an ethylene/vinyl acetate copolymer and an ethylene/ethyl acrylate copolymer are designated. A resin having thermal deformation properties lower than those of the resin used in the first laminate layer is employed in the second laminate layer and, when the first laminate layer is composed of the ethylene/vinyl acetate copolymer and the ethylene/ethyl acrylate copolymer, a high density polyethylene resin and a polypropylene resin are used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal transfer image receptor used for thermal transfer. More specifically, the present invention relates to a thermal transfer paper that is layered with a thermal transfer paper having an ink layer containing a sublimable dye and heated with a thermal head or the like to sublimate and transfer the sublimation dye to a dyeing resin layer to perform color recording. Concerning image receptors.

In recent years, with the spread of information terminals such as personal computers, word processors, televisions, and VTRs, the use of color displays has rapidly progressed, and the demand for printers that output these still images as color images has increased year by year. It has increased. Recording methods for such full-color printers include an electrophotographic method, an inkjet method, a thermal transfer method, and the like. Among these, the thermal transfer method is widely used because it is noiseless and the apparatus is easy to maintain.

This thermal transfer method consists of a combination of a fixed color ink sheet and an image receiving paper. Image formation is carried out by heat-melting transfer or sublimation transfer of ink from a thermal transfer paper (ink sheet) to a thermal transfer receiver paper using thermal energy controlled by electrical signals from a laser or thermal head, etc. Depending on the transfer method, it can be divided into thermal melt transfer type and sublimation transfer type.

In the case of the heat-melt transfer type, a heat-transfer recording sheet in which dyes or pigments are bound with a heat-fusible substance (generally wax) is used to transfer the color material layer melted by thermal energy from a thermal head etc. to a heat-transfer image receptor. do. This method generally has drawbacks such as difficulty in obtaining halftones, difficulty in obtaining a good hue due to the transferred heat-melting material, and vulnerability to surface abrasion.

On the other hand, a sublimation transfer type thermal transfer method using a sublimable or vaporizable dye is an application of conventional sublimation printing technology. This method generally uses a thermal transfer paper on which a disperse dye that easily sublimes is bound by a binder, and the dye is sublimated and transferred to a thermal transfer image receptor by the thermal energy of a thermal head to form an image. At this time, the amount of sublimable dye that corresponds to the amount of thermal energy in the thermal head sublimates, making it easy to obtain intermediate tones and having the advantage of being able to control the gradation arbitrarily, making it most suitable for full-color printers. It is considered to be a method.

As an image receptor for thermal transfer using this sublimation transfer type thermal transfer method, for example, Japanese Patent Laid-Open No. 57-107885 discloses that it can be effectively dyed with sublimable dyes such as saturated polyester resin, polyamide resin, and epoxy resin. It has been proposed that a dyeing resin layer made of a thermoplastic resin is provided on printing base paper.

When plain paper is used as the base material for such thermal transfer image receiving paper, the color density is generally lower than that of synthetic paper, the voltage of the thermal head must be increased, and the surface of the plain paper has large irregularities. Therefore, there are drawbacks such as uneven color density. On the other hand, when synthetic paper, ie, one made of polyolefin or polystyrene, is used as the base material, sufficient color density can be obtained and a fairly good image quality can be obtained. However, synthetic paper is generally stretched to increase its strength and ensure microscopic pores, so if it is heated only from the side with the dyeing resin layer using a thermal head during printing, shrinkage will occur. Distortion occurs between the front and back sides of the base material, resulting in significant curling.

In order to avoid this problem, we have developed a base material with a two-layer structure using synthetic paper with plain paper as the backing material, or a base material with a three-layer structure using plain paper as the core material and synthetic paper pasted on both sides. Materials have also been proposed. In particular, the three-layer base material not only reduces curl after printing, but also reduces curl during storage before printing, which is a drawback of two-layer base materials.
Furthermore, the unique feel of paper based on plain paper as a core material is maintained, and it has excellent properties.

Problems to be Solved by the Invention This three-layer structure base material is made by attaching synthetic paper, which usually has a multilayer structure of three or more layers, to both sides of plain paper as a core material with an adhesive (for example,
Adhesive with solvent-based adhesives such as acrylic, polyurethane, epoxy, and polybutyral; emulsion types such as polyvinyl acetate and ethylene-vinyl acetate copolymers; and aqueous adhesives such as polyvinyl alcohol. Created. For example, in a method for manufacturing synthetic paper using an internal paper forming method that applies biaxially stretched film forming, the central raw fabric layer is extruded into a film using an extruder, stretched in the longitudinal direction, and then extruded onto both sides of the raw fabric layer. Form a laminate layer using a machine. The laminate layer is then stretched in the transverse direction to generate microvoids in the laminate layer to produce synthetic paper. The synthetic paper thus prepared is further attached to both sides of the plain paper (core material). Therefore, many steps are required from the production of the synthetic paper to its attachment to the core material, and if the adhesive layer is included, the structure can be as many as 8 to LO layers. These numerous processes inevitably cause problems such as partial expansion (bulge) of the substrate during printing due to poor adhesion, or variations in the curl characteristics of the receiving paper substrate due to residual distortion during the adhesion or lamination process. is more likely to occur.

From this point of view, the structure of the base material has been simplified, the process has been simplified, and the base material has been manufactured by using plain paper as a core material and laminating general-purpose polyolefin resin such as polyethylene or polypropylene on both sides. There is.

FIG. 4 is a schematic cross-sectional view showing such a conventional thermal transfer image-receiving paper. Plain paper is used as a core material (1), and a general-purpose polyolefin resin such as polyethylene or polypropylene is laminated on both sides of the core material to provide laminate layers (12) and (12-). However, with such conventional image-receiving paper, sufficient adhesiveness cannot be obtained between the dyeing resin layer (3) and the laminate layer (12), and the dyeing resin layer (13) is easily bonded to the dyeing resin layer (13) before or after printing. ) peeling occurs. In addition, curling before and after printing can be done using the conventional internal paper method, PP.
Although it is smaller than a base material made of synthetic paper alone, it is larger than a base material with a three-layer structure in which synthetic paper is pasted on both sides of a core material. In other words, the curl under storage conditions before printing should be small since the image receiving paper base itself has a symmetrical three-layer structure, but when paper is laminated with an olefin resin with a low heat distortion temperature such as low-density polyethylene, In this case, it will become slightly larger due to the effects of heat and moisture. In addition, since the core material and the other laminate layer have a small restraint effect against thermal deformation of the dyeing resin layer and the laminate layer in contact therewith during printing, there is a drawback that curling becomes large after printing.

The purpose of the present invention is to eliminate such drawbacks of thermal transfer image-receiving paper, and to improve the adhesion between the dyeing resin layer and the laminate layer, and to provide a thermal transfer image-receiving paper with less curl before and after printing. The goal is to provide paper.

Means for Solving the Problems As a result of extensive research in order to solve the above problems, the present invention was developed by laminating a modified polyolefin resin with functional groups on one side of plain paper as a core material, and coating the surface layer with corona. The treatment improves the adhesion between the dyed resin layer and another laminate layer provided thereon, and also provides a laminate layer on the other side of the core material that has a lower thermal deformability than the material of the laminate layer. The present inventors have discovered that curling before and after printing can be reduced by using the method, and have completed the present invention.

That is, the present invention provides an image receptor base material having a core material, a first laminate layer provided on one surface of the core material, and a second laminate layer provided on the other surface of the core material, and A thermal transfer image receptor comprising a dyed resin layer provided directly or via an intermediate layer further outside the first laminate layer,
The first laminate layer is made of a modified polyolefin resin for the purpose of improving adhesion, and is subjected to surface oxidation treatment, and the second laminate layer is made of a resin having lower heat deformability than the resin of the first laminate layer. The present invention provides a thermal transfer image receptor characterized by:

The present invention will now be described in more detail with reference to the accompanying drawings. FIG. 1 is a schematic sectional view showing the basic structure of the image receptor of the present invention. As shown in FIG. 1, the image-receiving paper of the present invention consists of an image-receiving paper base material (10) and a dyed resin layer (3) provided on one surface thereof. The image receiving paper base material (10) is
It has a three-layer structure consisting of a core material (1), and a first laminate layer (2) and a second laminate layer (2') provided on both sides of the core material. The dyeing resin layer (3) is provided on the first laminate layer (2), and the surface of the second laminate layer is subjected to a surface oxidation treatment.

As the core material used in the image receptor of the present invention, commonly used plain paper is used, and the plain paper includes wood-free paper, medium-quality paper, art paper, coated paper, wallpaper, backing paper, synthetic resin or its emulsion. Alternatively, paper impregnated with synthetic rubber latex or the like, paper attached within a synthetic resin, etc. may be mentioned. The thickness of these core materials is preferably 30 to 300 μm.

In the image receptor of the present invention, the color density can be brought close to the level of synthetic paper by selecting the cushioning properties of the plain paper that is the core material or the thickness of the laminate layer. In addition, color unevenness can be reduced by using plain paper such as art paper or coated paper with small waviness as the core material.

A highly adhesive modified polyolefin resin is used for the first laminate layer on the dyeing layer side. Examples of such modified polyolefin resins include ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, and ionomer resins (for example, ionic copolymers of α-olefins such as ethylene and monomers having carboxyl groups). )
, ethylene-acrylonitrile copolymer, ethylene-styrene copolymer, ethylene-vinyl ether copolymer,
Examples include ethylene-maleic anhydride copolymer. Furthermore, inorganic fillers such as titanium oxide, inorganic pigments, and organic dyes may be added to these resins in order to improve the whiteness of the base material.

Such a laminate layer is subjected to surface oxidation treatment. The treatment is a chemical or physical treatment for improving the bonding properties of the surface of the laminate layer. For example, known treatment methods such as chromic acid treatment, ozone exposure treatment, corona discharge treatment, ionizing radiation treatment, flame exposure treatment, etc. used.

In this way, the image receptor of the present invention uses modified polyolefin, which has higher adhesiveness than general-purpose polyolefin, for the first laminate layer (2) adjacent to the dyeing resin layer (3), and has its surface treated with oxidation. Therefore, sufficient adhesion to the dyeing resin layer can be obtained. For this reason, adhesion is ensured even with polyester resin dyeing layers, which are widely used as dyeing resins and generally difficult to ensure adhesion, and peeling does not occur before or after printing. .

Further, for the other second laminate layer, a resin having lower thermal deformability than the resin used for the first laminate layer is used. As for the range of low thermal deformability, the amount of thermal deformation of the second laminate layer under a certain temperature increase condition is 8% of that of the first laminate layer.
It is preferably 0% or less.

Therefore, for the second laminate layer, for example, when the first laminate layer is made of ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, etc., high-density polyethylene resin, polypropylene resin, etc. are used. Moreover, when the first laminate layer is an ionomer resin made of ethylene and acrylic acid, polypropylene resin or the like is used.

In this way, since the second laminate layer (12-) is made of a plastic material with lower thermal deformability than the laminate layer (12) in contact with the dyeing layer, it has a structure that is close to symmetrical with respect to the core material and has a thermal deformability. It has a restraining effect against deformation and can reduce curling before and after printing. Here, thermal deformability means that the thermal deformation temperature is high, the thermal expansion coefficient is small, and the Young's modulus is large in the temperature range reached when heat is applied during printing.

In order to form the first and second laminate layers on the core material, lamination may normally be carried out by an extrusion method using a T-die or the like. The thickness of the first and second laminate layers is usually preferably 20 to 60 μm.

Further, as the dyeing resin layer, any known material having sufficient dyeability for sublimation dyes may be used. Examples of such materials include thermoplastic resins such as polyester resins, epoxy resins, polyurethane resins, polyamide resins, acrylic resins, cellulose acetate resins, butyral resins, vinyl acetate resins, and vinyl chloride resins, and mixtures or copolymers thereof. Can be used. These dyed resin layers may be partially crosslinked if necessary. In addition, fillers such as silica, talc, calcium carbonate, titanium oxide, zinc oxide, etc. may be added as necessary. To form these dyed resin layers, dissolve the resin in an appropriate solvent and apply gravure coating. The first laminate layer of the image receptor substrate is coated by a known method such as roll coating, reverse coating, wire bar coating, fountain coating, etc., and then dried. The thickness of the dyeing resin layer is preferably 5 to 15 μm.

The dyeing resin layer may be provided directly on the first laminate layer, or may be provided via an elastic intermediate layer (4°) as shown in FIG. The presence of the intermediate layer (4) improves the adhesion between the dyed layer of the image receptor and the ink layer of the thermal transfer paper, preventing a decrease in the color density of the image and occurrence of uneven color density due to poor adhesion. do. As such an intermediate layer, generally used are covalently crosslinked elastomers such as natural rubber, butyl rubber, and nitrile rubber, and synthetic resins such as polyurethane resins, acrylic resins, polyester resins, and polyolefin resins.

In addition, this intermediate layer (4) may contain conventionally known inorganic vulcanizing agents, organic vulcanizing agents, vulcanization accelerators, activators, anti-aging agents, mastication accelerators, softeners, and reinforcing agents, as required. , fillers, weather resistance improvers, etc. may be added.

The thickness of the intermediate layer is 1 to 50μ, preferably 3 to 15μ.
That's about it.

To form the intermediate layer, the material is dissolved in an appropriate organic solvent or prepared as an emulzidine solution to an appropriate viscosity, and then coated using any coating method such as a roll coater, kiss coater, gravure coater, or air knife coater. Apply and dry. Furthermore, when a thermoplastic material is used, extrusion coating using an accumator or the like may be performed.

Next, a method of printing using the image receptor of the present invention will be explained. FIG. 3 is a schematic cross-sectional view showing printing using the thermal transfer image-receiving paper and thermal transfer paper of the present invention.

The ink layer side of the thermal transfer paper (9) formed by laminating the ink layer (5) and the base film (6) faces the dyeing resin layer (3) of the image receiving paper, and the thermal head (7) and the platen roll (8) The ink is transferred by heating with a thermal head while bringing the ink into close contact with the ink.

Silver The thermal transfer image receptor of the present invention is produced by laminating a modified polyolefin resin having a functional group on one side of a core material and subjecting the surface layer to a corona discharge treatment, thereby forming a dyeing resin layer and a laminate layer provided thereon. The adhesion is improved. Also, since there is a laminate layer on the other side of the core material that has a lower thermal deformability than the material of the laminate layer on one side, the heat on both sides of the core material will increase. There is little difference in shrinkage rate due to this.

The image receptor for thermal transfer of the present invention has high adhesion between the image receptor base material and the dyeing resin layer, so there is no layer peeling, and the difference in heat shrinkage rate on both sides of the core material is small, so it can be used even before printing. Curling under storage conditions or after printing is reduced.

EXAMPLES Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples. In addition, in the following, "part" means "heavy!" means part. Curl before printing, curl after storage, and curl after printing were measured using the following methods.

[Curling due to storage conditions before printing] Image receiving paper of 100u + width x 12Bmm length at 40℃, 95%
It was left in a constant temperature and humidity chamber at RH and a constant temperature chamber at 60° C. for 24 hours. After taking out the image receiving paper and leaving it for 6 hours under normal conditions, place the image receiving paper (22) with the dyed resin layer facing down on a horizontal plate (21) as shown in Figures 5 and 6 to prevent curling. The highest value of the height h indicating the degree was measured.

[After printing, printing was carried out using the inventive image receiving paper of the present invention with a length of 100 Il + m x 128 mm and the following thermal transfer paper, and under the thermal head recording conditions of 6 dots/dot and an applied voltage of 0.4 w/dot to obtain the maximum image density. Ta. As shown in FIG. 7, the image receiving paper (23) was placed on a horizontal plate (21) with the printing surface facing up, and the maximum value of the height h, which indicates the degree of curl, was measured.

Thermal transfer paper: Sublimable disperse dye (Kayaset Red 12
6. Nippon Kayaku Co., Ltd.) 10 parts, polyamide resin (Hersalon 1140. Henkel Hakusuisha Co., Ltd.) 10 parts, toluene 40
An ink liquid consisting of 1 part and 40 parts of isopropyl alcohol was dispersed using ultrasonic waves for 6 hours. The ink liquid was coated on a 6μ polyester film with a gravure coater to a dry coating amount of 2.
g/+++" and dried to prepare thermal transfer paper.

[Adhesion] Using an image receiving paper of 100II+m width x 12Bmm length, make 1++-un goblets from the dyeing resin layer side with a cutter, apply cellophane tape over it, perform a peel test, and determine the adhesion by the number of remaining goblets. was evaluated.

Q: 80/100 or more remaining △ Near 9/100 to 30/100 Remaining Containing plastic composition (heat distortion temperature 50
℃, thermal expansion coefficient 2.8 x 10-'/''C).

The composition was extruded onto a coated paper with a weight of about 105 g per square meter using a T-die (180 to 200°C) and extruded to a thickness of 38 μm.
It was laminated to m. The laminate layer was subjected to corona discharge treatment (air gear length 1110.5n++a, voltage 600
0V, treatment time 100 m-5ec). Next, apply the density 0 to the other side of the coated paper in the same manner as above.
．． 95 g/cm3 of high-density polyethylene resin (heat deformation temperature 85°C, thermal expansion coefficient 2,7 x 10-'/'C) was laminated to a thickness of 25 μm using a T-die and an extruder at a temperature of 230 to 250°C. Then, an image receiving paper base material was formed.

On the other hand, as a dyeing resin liquid, 20 parts of a saturated linear thermoplastic polyester resin (Vylon #200, manufactured by Toyobo Co., Ltd.), 3 parts of a polyisocyanate compound (Coronate; manufactured by Nippon Urethane Co., Ltd.), amino-modified silicone (KF-393, (Manufactured by Shin-Etsu Chemical Co., Ltd.) 1 part, epoxy modified silicone (X-22-
343 (manufactured by Shin-Etsu Chemical Co., Ltd.), 40 parts of methyl ethyl ketone, and 40 parts of toluene.

The obtained dyeing resin liquid was applied to the corona discharge treated surface of the image receiving paper base using a wire cover, and the dry coating amount was 10%.
g/+''. This was dried at 90° C. for 2 minutes and further aged at 50° C. for 24 hours to prepare a thermoplastic transfer image-receiving paper as shown in FIG.

Table 1 shows the results of measuring the curl after storage conditions before printing, the curl after printing, and the adhesion of the thus obtained thermoplastic transfer image-receiving paper using the above method.

Example 2 Plastic composition containing 100 parts of ethylene-vinyl acetate copolymer (vinyl acetate content: 5 mol %) and 18 parts of titanium oxide (heat distortion temperature 52°C, thermal expansion coefficient 2.8 x 10-'/' C) was prepared. The composition was coated with a T-die (1
80~200℃) and an extruder to a thickness of approximately 38μm.
Laminated at.

The laminate layer was subjected to corona discharge treatment under the same conditions as in Example 1. Next, apply 230~ to the other side of the art paper.
A high-density polyethylene resin having a density of 0 and 96 g/cm 3 was similarly laminated at 250° C. using a T-die and an extruder to a thickness of 25 μm to form a receiver paper base material.

Next, a dyed resin layer was provided on the image-receiving paper base material in the same manner as in Example 1 to obtain a thermal transfer image-receiving paper. The resulting image-receiving paper was evaluated for curl after storage conditions before printing, curl after printing, and adhesion as described above. The results are shown in Table 1.

Comparative Example 1 Low density polyethylene resin 10 with a density of 0.92 g/cm3
Plastic composition containing 0 parts and 18 parts of titanium oxide (heat distortion temperature 55°C, thermal expansion coefficient 2.9X10-'
/'C) was prepared. The composition was weighed approximately 105g7m
A T-die (190 to 210°C) was used on an extruder to laminate the coated paper to a thickness of about 38 μm. The laminate layer was subjected to corona discharge treatment under the same conditions as in Example 1. Using the same method, apply 1 layer of low-density polyethylene resin with a density of 0°92g/c+a' to the surface of
25μ by an extruder using a T-die at 90-210℃
This was laminated to a thickness of m to form an image-receiving paper base.

A dyed resin layer was provided on the image-receiving paper base material in the same manner as in Example 1 to obtain an image-receiving paper for transfer. The obtained image-receiving paper was evaluated in the same manner, and the results are shown in Table 1.

Comparative PJ2 An image receiving paper was formed in the same manner as in Example 1 except that the laminate layer was not subjected to corona discharge treatment. The evaluation results of the obtained thermal transfer image receiving paper are shown in Table 1.

Example 3 A mixture of 20 parts of a thermoplastic elastomer (Califlex TRl007, manufactured by Shell Kagaku Co., Ltd.) and 80 parts of toluene was applied on the surface of the laminate layer (first laminate layer) which had been subjected to the corona discharge treatment of the receiver paper base material in Example 1. The solution was applied using a roll coater so that the dry coating amount was 10 g/dry, and dried to form an intermediate layer. Then, a dyeing layer resin was provided on the intermediate layer in the same manner as in Example 1. The resulting image-receiving paper was evaluated for curl after storage conditions before printing, curl after printing, and adhesion in the same manner as described above. The results are shown in Table 1.

Example 4 The first laminate layer and corona discharge treatment were performed in the same manner as in Example I. The second laminate layer is m degree 0,91
g/cm” polypropylene resin (heat distortion temperature 11
A receiver paper base material was formed by laminating to a thickness of 25 μm using an extruder using a T-die at a temperature of 240 to 270°C using a thermal expansion coefficient of 2.4 x 10-'/'C) at 5°C. . Next, a dyeing layer resin was provided by the same method as in Example 1. The resulting image receptor was evaluated for curl after storage conditions before printing, curl after printing, and adhesion in the same manner as described above. The results are shown in Table 1.

[Brief explanation of the drawing]

1 and 2 are simulated cross-sectional views of the thermal transfer image-receiving paper of the present invention, FIG. 3 is a schematic cross-sectional view showing printing using the thermal transfer paper and the image-receiving paper of the present invention, and FIG. 4 1 is a schematic cross-sectional view showing a conventional image receptor for thermal transfer, and FIGS. 5 to 7 are explanatory diagrams showing a method for measuring curl of the image receptor for thermal transfer. The main symbols in the figure are as follows.

Claims (2)

[Claims] (1) An image receptor base material having a core material, a first laminate layer provided on one surface of the core material, and a second laminate layer provided on the other surface of the core material, and a first laminate layer provided on the other surface of the core material; A thermal transfer image receptor comprising a dyed resin layer provided directly or via an intermediate layer on the outer side of a laminate layer, wherein the first laminate layer is made of a modified polyolefin resin for the purpose of improving adhesiveness. A thermal transfer image receptor, wherein the second laminate layer is made of a resin having lower heat deformability than the resin of the first laminate layer. (2) The thermal transfer image receptor according to claim 1, wherein the core material is plain paper.