JPH0699668A - Binderless porous donor film for forming dye diffusion type thermal transfer picture - Google Patents

Abstract

PURPOSE: To provide a thermal transfer donor film low in energy necessary for diffusing a dye into an image receiving layer (that is, high in heat sensitivity) and good in gradation properties. CONSTITUTION: In a film for forming a dye diffusion type thermal transfer image wherein a diffusible dye is physically caught in the pores of a porous film with a pore size of 20-400 Gurlex without being accompanied by a binder and a thermally diffusible transfer method for a dye image, a thermally diffusible dye donor sheet and a receiving sheet are allowed to be directly related to each other and the donor sheet is heated under temp. and/or pressure sufficient to transfer a dye from the donor sheet to the receiving sheet in a desired pattern. The donor sheet comprises a porous material having a thermally diffusible dye arranged in the pores of a porous material without being accompanied by a binder. By this constitution, the dye can be diffused by low energy and, therefore, the life of a thermal head is extended. Further, the donor sheet is high in heat sensitivity and image gradation properties.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a binderless porous donor film for producing a dye diffusion type thermal transfer image.

[0002]

2. Description of the Related Art A dye-diffusion type thermal transfer system is widely used because it can produce digitized image information by a non-impact system by a complete dry process and has a high continuous gradation. In this system,
Conventionally, a donor layer consisting of a dye and a polymeric binder fixed on a donor support film is brought into contact with an image receiving layer to be imaged, and a thermal treatment is performed on the surface of the donor support film opposite to the donor layer. Contact the head,
An image is formed by diffusing and fixing the dye in the donor layer onto the image receiving layer perpendicularly to the image receiving layer surface by the thermal energy supplied from the thermal head. FIG. 1 shows a schematic diagram thereof.

Such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 3-13.
386, 3-65394, 3-65395, and 3-8
6589. In a film using a conventional binder, a high affinity between the dye and the binder is necessary to sufficiently disperse the dye in the donor layer, but if the affinity is high, the dye diffuses to the image receiving layer. Requires high energy to drive the dye, and also the energy threshold for the thermal diffusion of the dye.
1d), there is a drawback that it is difficult to form an image having both high continuous gradation and high optical density with low energy.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention is capable of diffusing dyes with low thermal energy and is free of energy thresholds for thermal diffusion of dyes and has broad optical properties. An object of the present invention is to provide a donor film capable of forming an image having high continuous gradation even in the density range.

[0005]

As a result of various studies to solve the above problems, the present inventor has found that the pores of a porous film having a pore size of 20 to 400 Gurlex are used instead of the donor layer composed of a dye and a binder. By constructing the donor layer by physically encapsulating the diffusible dye without a binder therein, it is possible to diffuse the dye into the image receiving layer with low thermal energy and without an energy threshold. The inventors have found out what can be done and have completed the present invention.

Therefore, the present invention provides 20-400 Gurle
Provided is a dye diffusion type thermal transfer image forming film in which a diffusible dye is physically entrapped in the pores of a porous film having a pore size of x without a binder. A method of thermal diffusion transfer of a dye image for directly associating a thermal diffusion dye-donor sheet with a receiver sheet and transferring the dye in a desired pattern from the donor sheet to the receiver sheet. Heating at a sufficient temperature and / or pressure, and wherein the donor sheet comprises a porous polymeric material having a heat diffusible dye disposed in the pores of the porous material without a binder. Provide a way to do.

[0007]

Specific Description As the porous film used in the present invention, a polyethylene film, a polypropylene film, a polyester film, a polycarbonate film, a thin paper or the like can be used. The thickness of the film is 10 μm to 25 μm, preferably 1
It is 4 μm to 20 μm. The size of the hole is Gurlex
The value is 10 to 400, preferably 10 to 19. Specific examples of the porous film include polyethylene film # 0.
6106-5, polypropylene film # 770-2
8, polypropylene film # 770-2S, polypropylene film # 770-3S, polypropylene film # 770-4S, polypropylene film # 770-
6S, polypropylene film # 739-2B (all manufactured by US 3M Company), and the like can be used.

The pore size of the porous film is 20 to 400.
With a Gurlex pore size, a value greater than 400 makes it difficult to introduce dye into the pores, and a value less than 20 reduces the resolution of the image.
In the present invention, cyan dyes, magenta dyes, yellow dyes, and various other commonly used dyes can be optionally used. In order to accommodate these dyes in the pores of the porous film, these dyes are dissolved in a suitable solvent, for example, a general organic solvent such as tetrahydrofuran, methyl ethyl ketone, ethyl alcohol, etc., and this is applied to one side or both sides of the film, It may be applied by a conventional means such as a Mayer bar or a knife coater. Further, instead of coating, the porous film may be dipped in a coating solution. Next, this is dried and the solvent is removed to complete the formation of the donor layer. Since the coating solution does not include a binder, the dye does not accompany the binder, and the concentration of the dye in the dye solvent captured in the pores in the binder-free state varies depending on the type of the dye and the like. %, Preferably 2-7% by weight.

In a preferred embodiment of the present invention, a protective layer is provided on the surface of the porous film opposite to the surface provided with the donor layer in order to enhance the mechanical strength of the porous film. This protective layer of the present invention may be very thin, eg 1
It has a thickness of μm to 10 μm, preferably 1 μm to 3 μm. The protective layer is to prevent thermal influence from the thermal head, that is, fusion of the porous film, and the like. After applying on the opposite side,
It can be formed by drying. As a polymer for this purpose, polyvinyl alcohol, polyvinylpyrrolidone or the like can be used. As the solvent for this purpose, any solvent can be used as long as it dissolves the polymer used, and water, a mixture of water and a general hydrophilic organic solvent, or the like can be used. The concentration of the polymer in the solvent is 1 to 10% by weight,
Preferably 3-5 by weight%. In order to form the protective layer by the above method, one side of the porous film is coated with a dye solution and dried, and then the other side of the porous film is coated with a polymer solution for forming a protective layer and dried. do it.

The protective layer can also be provided by laminating thin films. As this film, a polyethylene terephthalate (PET) film, a polyethylene naphthalate (PEN) film, a polyimide film, a polyamide film, a polycarbonate film or the like is used. The image-receiving film to which the donor film of the present invention can be applied comprises a substrate film and an image-receiving layer formed on the surface thereof. The image-receiving layer is, for example, polyvinyl chloride, a copolymer of vinyl chloride and vinyl acetate,
Consists of layers of polyester, polycarbonate, etc. These are dissolved in an appropriate solvent, applied on the surface of the base film, and dried to form an image receiving layer. As the base film, a conventional one can be used.

[0011]

In the porous donor film of the present invention, the dye can be diffused with low heat energy, so that an image having high continuous gradation can be formed even when the optical density is low. . Also, the life of the thermal head is extended.

[0012]

EXAMPLES Next, the present invention will be described more specifically by way of Examples and Comparative Examples. (1) Preparation of Dye Mixture Each of the following dyes was dissolved in tetrahydrofuran (THF) and mixed to prepare. Concentration is 5% by weight
Was prepared.

1. Cyan dye mixture # 1 dye solution (trade name Foron, manufactured by sandos, USA)
Brilliant Blue solution) (Chemical formula 1) 4 g
+ # 2 dye solution (manufactured by 3M Company, USA) (Chemical formula 2) 5 g Magenta Dye Mixture # 3 Dye Solution (Mitsubishi Kasei, trade name HSR-31 Solution)
(Chemical formula 3) 3 g + # 4 dye solution (manufactured by 3M Company, USA) (Chemical formula 4) 4 g Yellow dye mixture # 4 dye solution (Nippon Kayaku, trade name MQ-452 solution)
(Chemical formula 5) 2g + # 6 dye solution (manufactured by 3M Company in the United States) (Chemical formula 6) 1g + # 7 dye solution (manufactured by 3M Company in the United States) (Chemical formula 7) 1g Chemical formulas 1 to 6 have the following structures.

[0014]

[Chemical 1]

[0015]

[Chemical 2]

(2) Preparation of donor The properties of the film used are as shown in Table 1. Table 1 ────────────────────────────────── Material Tm (℃) Thickness Gurlex (μm) sec / 50cc Air) ────────────────────────────────── polyethylene film # 06101-5 124-131 14 19 polypropylene film # 770-28 163-167 20 10 Polypropylene film # 770-2S 159-163 25 400 Polypropylene film # 770-3S 158-163 17 240 Polypropylene film # 770-4S 158-162 15 400 Polypropylene film # 770-6S 155- 160 10-Polypropylene film # 739-2B 158-162 20 34 Paper −22− ───────────────────────────────── A 7 type porous donor film was prepared.

Type 1 porous polyethylene film # 06101-5 (US 3
(Made by M Co.) on paper, and add THF solution of dye mixture to # 1.
The film was coated with 0 Meyer bar. 65
After drying at ℃ for 20 minutes, using a # 10 Meyer bar on the side of the film not coated with the dye, the degree of polymerization is 2000.
Was coated with a 5% by weight aqueous solution of polyvinyl alcohol and further dried under the same conditions.

A type 2 porous donor film # 06101-5 (manufactured by 3M Company, USA) was prepared by the same method as shown in type 1, and instead of being coated with polyvinyl alcohol, the thickness was 3.5 μm.
PET film was laminated. This lamination is 110 ° C using Gunma Ushio laminator.
It was performed at a speed of 9.5 mm / sec. FIG. 2 shows a film laminating process.

Type 3 porous film # 06101-5 (manufactured by 3M Company in the United States)
It was set on a PET film with a thickness of 3.5 μm and the dye mixture THF solution was coated on it with a # 10 Meyer bar. Then, it dried at 65 degreeC for 20 minutes. Type 4 porous film # 06101-5 (manufactured by US 3M Company)
The magenta dye mixture was immersed in a THF solution. 2 at 65 ° C
After drying for 0 minutes, it was laminated on a PET film having a thickness of 3.5 μm in the same manner as in Type 2.

Type 5 porous polypropylene donor film (# 770-2
8, # 770-2S, # 770-3S, # 770-4
S, # 770-6S, and # 739-2B) (US 3M)
Manufactured by the same company) was manufactured by the same method as Type 1. Type 6 porous polypropylene donor film (# 770-2
S) (manufactured by 3M Company, USA) was prepared in the same manner as in Type 1. However, it does not have a polyvinyl alcohol layer or a PET film layer. Further, when printing, no adhesive such as silicone grease against the thermal head or lubricant was used.

A donor film was prepared and evaluated in the same manner as in type 6 using type 7 thin paper. All samples, except the donor films used in Type 6 and Type 7, were coated with 2 wt% silicone grease in toluene on the non-dye coated side to prevent thermal head sticking, and then I wiped it lightly. (3) Preparation of Image Receptor Polyvinyl chloride (PVC) resin manufactured by Mitsubishi Kasei Vinyl was dissolved in tetrahydrofuran (THF) to prepare 5 wt% PV.
A C film solution was prepared. Further, anti-blocking agent solution (THF solution of 5 wt% FC430 (manufactured by 3M Co., USA))
Was prepared. Then, a mixed solution of them (10 g of PVC film solution + 0.5 g of FC430 solution) was coated on a (polyethylene terephthalate) (PET) film having a thickness of 4 mil with a # 20 Meyer bar, and then at 2 ° C at 65 ° C.
After drying for 0 minutes, it was used as an image-receiving film. (4) Thermal printer and printing conditions A thermal printer (manufactured by 3M Company, USA) having a thermal head of 200 dpi and a width of 13.4 cm was used for printing evaluation. Alternatively, a 1.95 kg weight was placed on the thermal head for pressurization. The scheme of the printed state is shown in FIGS. Printing was carried out in eight steps, and the voltage applied to the thermal head was also changed. Table 2 below shows the burn time and thermal energy.

Table 2 ────────────────────────────────── Steps 1 2 3 4 5 6 7 8 ─ ───────────────────────────────── Burn type / msec 0.56 1.12 1.68 2.24 2.80 3.36 3.92 4.48 Thermal energy 0.49 0.99 1.49 1.99 2.49 2.99 3.49 3.98 / Joule / cm ² (11.5V) Thermal energy 0.73 1.47 2.21 2.95 3.69 4.43 5.17 5.91 / Joule / cm ² (14.0V) Thermal energy 1.08 2.17 3.26 4.35 5.44 6.53 7.62 8.71 / Joule / cm ² (17.0V) ────────────────────────────────── (5) Image density evaluation of the printed image For optical transmission density measurement, a decintometer Macbeth TR924 (Macbeth Pr
ocess Measurment) was used. A type A filter was used.

Example 1 A type 1 porous donor film was tested at an applied voltage of 11.5 volts. Then, the image gradation which changed linearly was shown. The result is shown in FIG. When the applied voltage was 11.5 V or higher, heat partially melted the donor film. These donor films did not cause sticking to the image receiving layer or transfer of dye to the image receiving layer by pressure alone.

Comparative Example 1 Three types of ink ribbons (cyan, magenta, and yellow) having different dyes were prepared as shown in FIG. First, a dye solution consisting of a dye, cellulose acetate, an anti-blocking agent and MEK was coated on a 6 μm PET film using a # 10 micker bar, and then dried in an oven at 60 ° C. for 10 minutes. Evaluated in the same way as in Example 1 using the ink ribbons thus obtained with a donor layer 7 with a thickness of 5 μm, they are lower than the type 1 porous donor film with respect to the applied thermal energy. It showed sensitivity. The result is shown in FIG. That is, they required higher energy for dye diffusion than Type 1 films.
Furthermore, the magenta ink ribbon transferred the dye to the image receiving layer only by pressure.

Comparative Example 2 To make cyan, magenta, and yellow ink ribbons, a # 10 Meyer bar was used to apply three dye mixture solutions of PE with a thickness of 6 μm.
After being coated on a T film, dried, and evaluated in the same manner as in Example 1. The result is shown in FIG. 7. They showed almost no gradation. Only the magenta ink ribbon appears to have gradation, but the image shows the transfer of solid dye. Most images were made by mass transfer.

Example 2 A type 2 donor film was chosen to improve the thermal properties. The printing conditions are the same as in Example 1 except for the applied voltage. The applied voltage was increased from 11.5 volts to 14.0 volts. For the optical density of the printed image and the thermal energy from the thermal head,
Similar to the first embodiment, a clear linear relationship is established. The result is shown in FIG.

Further, the thermal sensitivity for dye diffusion was kept high. No transfer of the dye to the image-receiving layer due to pressure alone was observed. Comparative example 3 . Using the same dye, type 3 shown in FIG.
Various types of ink ribbons were produced and evaluated in the same manner as in Example 2. The result is shown in FIG. Only the magenta ink ribbon showed good thermal sensitivity compared to the other two, but showed transfer to the image receiving layer due to pressure. Therefore, Dmin is high. The cyan ink ribbon adhered to the image receiving layer at the 7th level or higher. Overall, these thermal sensitivities were lower than type 2 donor films.

Comparative Example 4 Three types of commercially available ink ribbons manufactured by Company A were evaluated in the same manner as in Example 2. The result is shown in FIG. Their thermal sensitivity was low except for the yellow ink ribbon. Comparative example 5 . Three types of commercially available ink ribbons manufactured by Company B were evaluated in the same manner as in Example 2. The result is shown in FIG. All ink ribbons have low thermal sensitivity and range of printed image density, Dmax to Dmin.
Until was too narrow.

Comparative Example 6 Three types of commercially available ink ribbons manufactured by Company C were evaluated in the same manner as in Example 2. The result is shown in FIG. They also showed low thermal sensitivity and had a narrow coverage. Example 3 . A type 3 porous donor film was prepared to extend the Dmax and Dmin range of the printed image. The printing conditions are the same as in the second embodiment. These optical densities are in a linear relationship with the applied heat energy, and for producing a cyan image showing an optical density of 2.0,
It required 5.1 Joule / cm ² , and for magenta and yellow images it required 5.9 Joule / cm ² . The results are shown in Fig. 13. These energy values are extremely low as compared with those of commercially available donor films.

Example 4 When the type 4 porous donor film was evaluated by the same method as in Example 2, the gradation of the image was recognized. The results are shown in Fig. 14. In this example, it is considered that no special coater is required for making the donor film. However, a process of immersing the porous film in the dye solution is necessary.

Example 5 The applied voltage was set to 17.0 V and the type 5 porous polypropylene donor film (# 770-28) (manufactured by 3M Company, USA) was evaluated by the same method as in Example 1 except for the applied voltage. A linear relationship was found between the optical density of the printed image and the thermal energy applied during printing. This result is shown in Figure 1.
5 shows. Example 6 . Example 5 A type 5 porous polypropylene donor film (# 770-2S) (manufactured by 3M Company, USA)
As a result of evaluation in the same manner as in 1., gradation was found in the printed image. Moreover, it changed linearly with the applied heat energy. The result is shown in FIG.

Example 7 The type 6 porous polypropylene donor film (# 770-2S) was evaluated by the same method as in Example 5, and almost the same result as in Example 6 was obtained. The result is shown in FIG. From these results, the heat transfer of the dye in the pores from the basic donor layer to the image receiving layer does not require polyvinyl alcohol or PET film as shown in FIG. 3 and should be performed by the donor as shown in FIG. Can be done.

Example 8 The type 5 porous polypropylene donor film (# 739-2B) (manufactured by 3M Company, USA) was evaluated by the same method as in Example 5, and as a result, the image printed on the image receiving layer had gradation, and the image was obtained. The optical density of was linearly related to the applied heat energy. The results are shown in FIG.

Example 9 The type 5 porous polypropylene donor film (# 770-3S) (manufactured by 3M Company, USA) was evaluated by the same method as in Example 5, and as a result, the image printed on the image receiving layer had gradation. The optical density of the image was linear with the applied heat energy. The result is shown in FIG.

Example 10 The type 5 porous polypropylene donor film (# 770-4S) manufactured by 3M USA) was evaluated by the same method as in Example 5, and as a result, the image printed on the image receiving layer had gradation. The optical density of the image was linear with the applied heat energy. The result is shown in FIG.

Example 11 A type 5 porous polypropylene donor film (# 770-6S) (manufactured by 3M, USA) was evaluated in the same manner as in Example 5, and as a result, gradation was obtained in the image printed on the image receiving layer. . The optical density of the image was linear with the applied heat energy.
The result is shown in FIG.

Example 12 The thin paper coated with the type 7 red dye was evaluated in the same manner as in Example 5. The image printed on the image-receiving layer showed a density change in a slight range. The result is shown in FIG. As a result, even a film that does not undergo pore deformation, shrinkage, or melting due to heating may be used as a binder-free donor.

As described above, in all the donor films of the present invention, the burn time and the image density were in good proportion and showed extremely good gradation.

[Brief description of drawings]

FIG. 1 shows (with a general donor film configuration).
3 shows an image forming system of a comparative example.

FIG. 2 shows a laminated state during the production of the type 1 laminated film of the present invention.

FIG. 3 shows an example of an image forming system to which the donor film of the present invention is applied.

FIG. 4 shows an example of an image forming system to which the donor film of the present invention is applied.

FIG. 5 shows the relationship between burn time and image density obtained in Example 1.

FIG. 6 shows the relationship between burn time and image density obtained in Comparative Example 1.

FIG. 7 shows the relationship between burn time and image density obtained in Comparative Example 2.

FIG. 8 shows the relationship between burn time and image density obtained in Example 2.

FIG. 9 shows the relationship between burn time and image density obtained in Comparative Example 3.

FIG. 10 shows the relationship between burn time and image density obtained in Comparative Example 4.

11 is a graph showing the relationship between burn time and image density obtained in Comparative Example 5. FIG.

FIG. 12 shows the relationship between burn time and image density obtained in Comparative Example 6.

FIG. 13 shows the relationship between burn time and image density obtained in Example 3.

FIG. 14 shows the relationship between burn time and image density obtained in Example 4.

FIG. 15 shows the relationship between burn time and image density obtained in Example 5.

FIG. 16 shows the relationship between burn time and image density obtained in Example 6.

FIG. 17 shows the relationship between burn time and image density obtained in Example 7.

FIG. 18 shows the relationship between burn time and image density obtained in Example 8.

FIG. 19 shows the relationship between burn time and image density obtained in Example 9.

FIG. 20 shows the relationship between burn time and image density obtained in Example 10.

FIG. 21 shows the relationship between burn time and image density obtained in Example 11.

FIG. 22 shows the relationship between burn time and image density obtained in Example 12.

Claims (6)

[Claims] 1. A dye diffusion type thermal transfer image forming film in which a diffusible dye is physically entrapped in a pore of a porous film having a pore size of 20 to 400 Gurlex without a binder. 2. The film according to claim 1, wherein the porous film is a porous polyethylene film or a porous polypropylene film. 3. The film according to claim 1, wherein a protective layer is applied or laminated on one surface of the porous film. 4. A method of thermal diffusion transfer of a dye image, wherein a thermal diffusion dye-donor sheet is directly associated with a receiver sheet, and the donor sheet is provided with the dye in the desired pattern from the donor sheet to the receiver sheet. Heating at a temperature and / or pressure sufficient to cause the transition to a porous polymeric material having a heat diffusible dye disposed in the pores of the porous material without a binder. A method of having. 5. The method according to claim 4, wherein the porous material is a porous polyethylene film or a porous polypropylene film. 6. The method according to claim 4, wherein a protective layer is applied or laminated on one surface of the porous material.