JPH02160588A - Particulate polypropylene wax - Google Patents

Abstract

PURPOSE: To remove and alleviate a liquid-like defect on a print and to create a sufficient gloss by incorporating one or more types of particulate polypropylene was having a specific mean particle size and a melting point in a dye layer. CONSTITUTION: A dye layer containing a dye dispersed in a polymer binder contains one or more types of particulate polypropylene was having a mean particle size of less than 30 μm and a melting point of 125 deg.C or higher. The wax is normally used at 0.005 to 0.2 g/m<2> . This wax is sold at the ambient temperature, and when the temperature is gradually raised, it is melted, and a viscosity in a liquid state is less than 8000 cPs. Preferably, as a dye binder, a cellulose acetate butyrate or cellulose acetate propionate is used. And, in the case of a dye for transferring to a dye acceptive layer by a thermal action, any dye can be used for the dye layer of the dye donor element.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dye-donor element for use in thermal transfer of dyes. More particularly, it relates to the use of granular polypropylene wax in the dye layer to reduce various defects that occur during printing operations without compromising gloss.

PRIOR ART In recent years, thermal transfer systems have been developed for the purpose of printing images electrically produced by color video cameras. According to one method developed, the colors of an electrical image are first separated using color filters, and each color image is converted into electrical signals. Cyan, magenta, and yellow electrical signals are then generated from these electrical signals and sent to the thermal transfer device. In a thermal transfer device, cyan, magenta and yellow dye-donor elements are placed in close proximity to a dye-receiver element for printing.

These two elements are inserted between the thermal transfer head and a hot platen roller such that the linear thermal transfer head applies heat from the back side of the dye donor sheet.

The linear thermal transfer head has a number of heating elements, each of which is continuously heated in response to cyan, magenta and yellow electrical signals. In this way, a color hard copy corresponding to the image on the screen is obtained. This process and the equipment for carrying out this process were developed by Braunstein (B.
U.S. Pat.
No. 71 (dated November 4, 1986) provides more details.

Column 6 of U.S. Patent No. 4,720,480, Japanese Patent No. 62/2g3,176 and European Patent No. 210,8
No. 38 describes the use of various materials in the dye layer of the dye-donor element, such as silicone oils, polyalkylene glycols, paraffin waxes, fluorocarbon resins, solid particulate lubricants, and polyethylene waxes.

(Problems to be Solved by the Invention) When thermal dye transfer is performed, defects on prints are often observed. For example, small untransferred areas called "mottles" may be observed on the dye-receiving layer, or "wavy defects" resembling ripples that can be seen through ports against flow. .

“The wavy defect J is caused by the uneven speed at which the dye-donor element passes through the nip (+ip) created by the dye-receiving element and the thermal print head. The image becomes difficult to distinguish in low-density areas, and the maximum density becomes low.

As is clear from the comparative tests described below, the above-mentioned prior art materials are unable to eliminate or reduce the various printing defects mentioned above, and are not capable of eliminating or mitigating the various printing defects mentioned above, and are not sufficient to meet the particular requirements of reflective printing. Many of them do not have a glossy luster.

The present invention therefore aims at the use of particles in the dye layer of a dye-donor element in order to be able to eliminate and reduce the above-mentioned print defects and to produce sufficient gloss.

(Means for Solving the Problems) The above objects and other objects have been achieved by the present invention. The present invention relates to a dye-donor element for thermal transfer of dyes having a dye layer containing a dye dispersed in a polymeric binder; A dye-donor element characterized in that it also contains one or more particulate polypropylene waxes.

Particulate polyethylene wax may be used in the present invention in any amount that effectively accomplishes the intended purpose. Normally, good results can be obtained by using o,oos~0.2 (7 m).

As used herein, "wax" refers to a plastic that is solid at ambient temperature, melts with gradual increase in temperature, and has a viscosity in the liquid state of less than 8000 cps.

Examples of granular polypropylene waxes that can be used in the present invention include the following:

Compound l) Ultra-finely pulverized polypropylene particles such as M 1cropro-400'' manufactured by Micro Powder Co., Ltd. having a melting point of 140-143°C. Finely ground polypropylene particle compound 3) Jamrock Technology's Net-5kid 53 g 98 with a melting point of 140-155°C
4) Polypropylene particles such as Eastman Chemical Products' EpoIene N-15' having a melting point of 163° C. The dye used in the dye-donor element of the present invention can be disperse inside. As the polymer binder, for example, cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate,
Use of cellulose derivatives such as cellulose acetate butyrate, cellulose triacetate and the materials described in U.S. Pat. Can be done.

A preferred embodiment of the invention uses cellulose acetate butyrate or cellulose acetate propionate as dye binder. The amount of acetyl is 1.5~
31%, propionyl 38-48% and butyryl 1
It is 5-56%.

If the dye can be transferred to the dye-receiving layer by the action of heat,
Any dye can be used in the dye layer of the dye-donor element of the present invention. Particularly good results are obtained using sublimable dyes such as the compound represented by the following structural formula: or any of the dyes disclosed in U.S. Pat. No. 4,541,830. These dyes may be used alone or in combination to form monochromatic images. The dye is preferably hydrophobic and the coverage is between 0.05 and 1! /l
! You can also use it as

The dye layer of the dye-donor element may be coated or printed onto the support by printing techniques such as gravure printing.

The support for the dye-donor element of the present invention may be any material that is dimensionally stable and capable of withstanding the heat of the thermal print head. As such a substance,
For example, poly(ethylene terephthalate), polyamide,
Mention may be made of polyesters such as polycarbonate, glassine paper, condenser paper, cellulose esters, fluoropolymers, polyethers, polyacetals, polyolefins and polyimides. The thickness of this support is usually 2~
30μ garden, and U.S. Patent No. 4゜695.2 as necessary.
88 and 4,737,486.

The back side of the dye donor element may be coated with a slip layer to prevent the dye donor element from sticking to the printhead. The slip layer is described in U.S. Pat. No. 4,717,711;
17,712 and 4,738.950. Polymer binders used for the slipping layer include poly(vinyl alcohol-cobutyral) and poly(vinyl alcohol-coacetal).
, poly(styrene), poly(vinyl acetate), cellulose acetate butyrate, cellulose acetate gropionate, cellulose acetate and ethyl cellulose, and the like are suitable.

The amount of lubricant used in the slip layer varies greatly depending on the type of lubricant, but is usually between 0.001 and 2! /Otori 3. When using a polymeric binder, the lubricating substance is 0.1 to 50% by weight of the polymeric binder, preferably 0.5 to 4% by weight of the polymeric binder.
Use 0% by weight.

The dye-receiving element used with the dye-donor element of the present invention consists of a support having a dye image-receiving layer on its surface. The support may be a transparent film such as poly(ether sulfone), polyimide, cellulose ester such as cellulose acetate, poly(vinyl alcohol-coacetal) or poly(ethylene terephthalate).

The support for the dye-receiving element may also be reflective, such as baryta-coated paper, polyethylene-coated paper, white polyester (polyester mixed with white pigments), i-poly paper, condenser paper, or synthetic paper such as duPomt Tyvek. It may be something that you have.

The dye image-receiving layer may contain, for example, polycarbonate, polyurethane, polyester, polyvinyl chloride, poly(styrene-co-acrylonitrile), poly(caprolactone) or mixtures thereof. The dye image-receiving layer may be present in an amount that effectively accomplishes the objectives of the invention. Usually, a concentration of 1 to 5 (7 m) will give good results.

As mentioned above, dye donor elements are used to form dye transfer images. Transfer of the dye image is accomplished by imagewise heating the dye-donor element as described above and transferring the dye image onto the dye-receiving element to form a dye transfer image.

The dye-donor element of the present invention may be used in the form of a sheet, continuous roll or ribbon.

In continuous rolls or ribbons, dyes may be used in one color or alternatively with dyes other than those mentioned above, such as sublimable cyan and/or magenta and/or yellow and/or black. . Such dyes are described in U.S. Pat.
No. 698,651, No. 4,695,287, No. 4.7
No. 01.439, No. 4,757,046, No. 4,74
No. 3,582, No. 4,769,360 and No. 4,7
No. 53,922. Such monochromatic, dichromatic, trichromatic, or tetrachromatic (or more colored) elements are included within the scope of the present invention.

In a preferred embodiment of the invention, the dye-donor element has a poly(ethylene terephthalate) support repeatedly coated with yellow, cyan, and magenta, and each of these three colors is subjected to the operations described above to obtain the three colors. A dye transfer image is obtained.

It goes without saying that this step may be performed in a single color to transfer a single color dye image.

The thermal dye transfer body using the present invention consists of (a) the above-mentioned dye-donor element and (b) the above-mentioned dye-receiving element, and since the dye-receiving element is superimposed with the dye-donor element, the dye of the dye-donor element is The layer is in contact with the dye image-receiving layer of the dye-receiving element.

Example The present invention will be explained below by giving examples.

Example 1 - Print Defect Testing A cyan dye-donor element was prepared by coating the following layers on a 6 μm poly(ethylene terephthalate) support.

1) Titanium alkoxide coated from a mixed solvent with n-propyl acetate and n-butanol (duP+mt
T7zor TIIT”Xo, 12 t/m subbing layer 2) Cellulose acetate propionate (2,5% acetyl, 45% propionyl) binder (0,44 g) coated from a mixed solvent of toluene, methanol and cyclopentanone /m'') of the above-mentioned cyan dye (0,
28g/Otori”), and particulate matter shown in Table 1 (0,
Dye layer containing 08t/cm.

Titanium alkoxide (du
Pol Tysor TBT”) (0,12(/m
”) and coated with a subbing layer of Hänsel (Hsnx
el) et al., U.S. Application No. 062,797 (June 1987)
It was coated with a slip layer similar to that disclosed in US Pat.

The dye-receiving element is poly(acrylonitrile-vinylidene chloride-co-acrylic acid) (weight ratio 14 to 9 nia)
Mskro coated from methylene chloride was prepared by coating the following layers on a support of poly(ethylene terephthalate) pigmented with titanium dioxide and primed with: Mskro coated from methylene chloride.
lu+ 5705” (BBer AG) Polycarbonate resin (2.9 g/m, 1.4-didecoxy 2.
6-Simethoxyphenol (o, 3st/Otori'), FC
-431” surfactant (3M) (o, 016 g/
DC-510” surfactant (0,011g/
m”).

The combined dye transfer was such that the dye side of the strip of dye-donor element having an area of about 10 cv x 13 c was in contact with the dye image-receiving layer of the dye-receiving element in the same area. This dye transfer body was placed on a take-up device driven by a rubber roller with a diameter of 60 mm.

A TDK thermal head L-231 (thermostat 26° C.) was pressed from the side of the dye donor element towards the rubber roller with a force of 8.0 bond (3.6 k*).

The imaging electronics were activated to draw the dye transfer between the printhead and the rollers at 6.9 mm/sec. At the same time, the resistor of the thermal print head was heated in pulses of 29 microseconds every 128 microseconds for a print time of 33 milliseconds per dot. Images with varying densities were drawn by increasing the number of pulses per dot from 0 to 255. The power supplied to the thermal print head was approximately 23.5V, resulting in an instantaneous peak power of 1.3 Watts/dot and a maximum total energy supply of 9
．． The price became 6 millisir/dot.

The dye-receiving element was separated from the dye-donor element and the unprinted areas were examined. Evaluation was performed in the following four stages.

0-No unprinted area 1-Print be 2-pudding be 3-pudding stomach The results were as shown below.

Control compound 1 Control compound 2 Control compound 3 Control compound 4 Control compound 5 Control compound 6 Control compound 7 (PTFE) (Silica) (Silica) (Silica) (Silica) (PE) (PE) i) There were so many wavy defects that it was difficult to separate the dye-donor layer from the dye-receiver layer.

Control compound 1 DI, X-6000" polytetrafluoroethylene micropow'/-(dmPo*L) with particle size <11 m Control compound 2 Z to 49" (J, M,
Precipitated amorphous silica control compound 3 Z eorree 153” (J
Precipitated amorphous silica control compound 4 Z eosyl file with an average particle size of 5 mm (J
Precipitated amorphous silica control compound 5 Z eothix 177” with an average particle size of 1.5 JIm
(J, M, 11++ber) Precipitated amorphous silica control compound 6 M 1crof iae M with melting point 104-110°C
8-F (Astor Wax) Polyethylene Wax This material is disclosed in Japanese Patent No. 62/238,176.

Control Compound 7 MPP620XF1 polyethylene wax with a melting point of 114-116°C (Micro PovdCrs) Addition of granular polyethylene wax or polypropylene wax to the dye layer results in less unprinted area than when using conventional granular materials. is clear from the above results.

However, as shown in Example 3, polyethylene wax has other problems.

Example 2 - Print Defects Example 1 except that particulate matter is included in the amounts shown in Table 2.
A dye-donor element was manufactured by the same method as described above. Also,
Coat the subbing layer with 0.16 t/m" and use the above yellow dye instead of cyan dye (0.16 K/ln) and binder at 0.29 t/m" according to Table 2. A control yellow dye-donor element was also prepared by the same method as Example 1, with each particulate material present in the amounts indicated.

Poly(acrylonitrile-vinylidene chloride-coacrylic acid) coated from 2-butanone (14nia 9nia wt% The dye-receiving element was prepared by coating the layers in sequence.

1) Mskrolon 57 coated from methylene chloride
05” (Bayet AG) polycarbonate resin (
2.9t/a, T++ae PCL-300” Polycaprolactone (Union Carbide X0.38g/
ToIle PCL-3 coated from methylene chloride and 1,4-didecoxy 2,6-simethoxyphenol (0,38 t/dye-receiving layer 2) methylene chloride
00' Polycaprolactone (Union Carbide) (
Preparation of topcoat layer consisting of FC-431" surfactant (3M) (0,01 g/m') and DC-510" surfactant (DovCareing) (0,01 (7 m")) Printing was performed as in Example 1 using dye-donor and dye-receiver elements.
It was investigated whether "wavy defects" were observed. The results were as shown below.

Table 2-1 Control Compound 6 (PE) Control Compound 7 (PE) Compound 3 (Invention) Control Compound 1 (PTFE) Control Compound 8 (Castor Oil) Control Compound 9 (PEG) Control compound 6 (PE) Control compound 7 (PE) Compound 3 (invention) Control compound 1 Control compound 8 (without control) Control compound 6 (PE) Control compound 7 (PE) Compound 3 (invention) Castor oil) Y Non-control compound 9 (PEG) Y Control compound 10
(Paraffin) y-bl Note) C indicates cyan and Y indicates yellow.

a) Results were mixed due to difficulty in preventing particle agglomeration before coating.

b) When kept at 60'O for 70 hours, this material crystallized the dye in the dye-donor layer, making it difficult to print uniformly. In areas of the dye-donor element where the dye crystallized, the maximum density of the print was reduced due to loss of discrimination in areas of low density.

Control Compound 8 Castor Oil Control Compound 9 Polyethylene Glycol Control Compound 10 Molecular Weight 1300-1600°C Paraffin Wax Compared to conventional granular materials that produce wavy defects, the use of granular polyethylene wax or polypropylene wax generally produces less wavy defects. It is clear from the above results that it is possible to form an image that is However, as shown in Example 4, polyethylene wax has other problems.

Example 3 - Separation Failure Test Cyan and yellow dye-donor elements were prepared according to Example 2.

Poly(acrylonitrile-vinylidene chloride-coacrylic acid) coated from 2-butanone (14 nia 9 nia wt%) (0,08 g/fat 2) on polyethylene coated paper stock colored with titanium dioxide, primed with a layer of Dye-receiving elements were prepared by coating the following layers: Makrolo coated from methylene chloride.
5705" (Bayer AG) Polycarbonate resin (211/+m") and 1,4-didecoxy 2,6-simethoxyphenol (0,38 g/L2) Dye-receiving layer line-shaped dye-donor element and dye Printing was performed as described in Example 1 using the receiving element. The ease of separation of the dye-receiving element from the dye-donor element was compared after multiple transfers from the dye-donor element to the same area of the dye-receiver element. The evaluation was performed according to the following steps.

E- Even after multiple printing of less than 6 degrees, the dye-donor element and dye-receiving element can be separated cleanly and easily. Because they stick to each other, it takes moderate effort to separate them.

P-The dye layer sticks to the dye-receiving layer after only one print, requiring more effort to separate the two.

The results were as shown below.

(without control) 0M Control Compound 6 (PE) CM Control Compound 7
(PE) -P Compound 3 (invention) Control compound 1 (PTFE) Control compound 8 (Castor oil) Control compound 9 (PEG) Control compound 6 (None control) CM control compound 6 (
PE) CM-E Control Compound 7 (PE) CM-E Compound 3 (
Invention) Control without CE)
YM control compound 1 (PTFE) Y
E'') Control Compound 8 (Castor Oil) Yp Control Compound 9 (PEG) Y p Control Compound 10 (Paraffin) Y E'') Note) C indicates cyan and Y indicates yellow.

a) Results were mixed due to difficulty in preventing particle agglomeration before coating.

b) When kept at 60°C for 70 hours, this substance crystallized the dye in the dye-donor layer, making it difficult to print uniformly. In areas of the dye-donor element where the dye crystallized, the maximum density of the print was reduced due to loss of discrimination in areas of low density.

It is clear from the above results that the dye-donating element can be easily separated from the dye-receiving element when the granular polypropylene wax is used, whereas the conventional particulate material makes it difficult to separate the dye-donating element from the dye-receiving element. Although some conventional particulate materials can be separated cleanly, they have other undesirable properties as shown in Examples 2 and 4.

Example 4 - Comparative gloss test A dye receiving element was manufactured in the same manner as in Example 2.

Cyan dye-donor elements were prepared in the same manner as in Example 1 except that the amounts of particulate material shown in Table 4 were included. Printing was performed using the dye-donor and dye-receiver elements as described in Example 1, except that the supply power was 24.5 V and 255 pulses/dot to produce a uniform, full-density image.

The dye-receiving element is separated from the dye-donor element to perform biological research.
The gloss (regular reflectance at a predetermined angle of incidence) was evaluated using a multi-angle digital gloss meter (Tory Inc.). A high reflectance is desirable because it means a high gloss. The results were as shown below.

(without control) 25 73 Control compound 6 (PE) 18 59 Control compound 7 (
PE) 29 68 Compound 3 (invention)
35 74 (control) 2
5 73 Control compound 6 (PE) 14
50 Comparative Compound 7 (PE) 11 43 Compound 3 (Invention) 21 66 The dye-donor element of the invention containing polybrobylene wax has a higher reflectance than the conventional dye-donor element containing polyethylene wax. It is clear from the above results that this is large.

(Effects of the Present Invention) If particles are used in the dye layer of a dye-donor element according to the present invention, defects on prints can be removed and reduced, and sufficient gloss can be obtained on the surface.

(Contrast without) Control compound 6 (PE) Control compound 7 (PE)

Claims (1)

Claims: A dye-donor element for use in thermal transfer of dyes having a dye layer containing a dye dispersed in a polymeric binder; said dye layer having an average particle size of less than 30 μm and a melting point of 1.
A dye-donor element characterized in that it also contains one or more granular polypropylene waxes with a temperature higher than 25°C.