JP3097903B2 - Laser recording element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to laser recording elements and, more particularly, to a single sheet laser recording element wherein the support is a composite film having micropores.

[0002]

2. Description of the Related Art Thermal transfer systems have recently been developed to obtain prints from images that are generated electronically from a color video camera. According to one method of obtaining such prints, an electronic image is first subjected to color separation by color filters. Then, each color separation image is converted into an electric signal. These signals are manipulated to generate cyan, magenta, and yellow electrical signals and transmit these signals to a thermal printer. To obtain a print, a cyan, magenta or yellow dye-donor element is placed face-to-face with a dye-receiving element. Then, these two are inserted between the thermal print head and the platen roller. Heat is applied from the back of the dye-donor sheet using a line-type thermal printhead. The thermal print head has many heating elements and heats continuously according to cyan, magenta or yellow signals. This process is then repeated for the other two colors. In this way, a color hard copy corresponding to the original video seen on the screen is obtained.

US Pat. No. 5,244,861 relates to a dye-receiving element useful in the thermal dye transfer process described above, comprising a composite film having microvoids as a support. This patent does not state that the support is useful in other thermal systems. Another method of applying heat to obtain a print using the electrical signals described above is to use a laser instead of a thermal printhead. In such a laser transfer system, the donor sheet contains a material that strongly absorbs at the wavelength of the laser. Upon irradiation of the dye-donor, the absorbing substance converts light energy into heat energy and conducts the heat to the nearby dye, thereby
The dye is heated to its evaporation temperature and transferred to a receptor.
The absorbing material may be present in the layer immediately below the dye and / or may be mixed with the dye. The area where its presence is required on the receptor, which modulates the laser beam by an electrical signal corresponding to the shape and color of the original image, thus heating the respective dye and reconstructing the color of the original object Only cause evaporation. Details of this process are described in GB 2,083,726A.

[0004] Another mode of imaging using a laser beam involves image dyes, infrared absorbing materials,
A laser recording element having a dye layer composition comprising a dye and a binder is imaged from the dye side. The energy provided by the laser repels the image dye and other components of the dye layer where the laser beam hits the element.
In "laser removal" imaging, laser irradiation is used to cause a rapid local change in the imaging layer, thereby removing the material from the layer. The usefulness of such a laser recording element is largely determined by the efficiency of the imaging dye removed during laser exposure.
The transmission Dmin value is a quantitative measure of dye cleanout (the lower its value at the recording spot, the more complete the achievement of dye removal).

[0005] US Patent 5,330,876 relates to a dye ablative recording element as described above. The element comprises a support having thereon an image dye, an IR absorbing dye and a binder. The element is imagewise exposed with a laser to ablate portions of the dye layer to produce a dye image. The support for this element is a conventional support used in the art.

[0006]

A problem with the above dye ablative recording elements is that the minimum density and sensitivity are not as good as desired. It is an object of the present invention to provide a dye ablative recording element with improved minimum density and sensitivity over the prior art. It is a further object of the present invention to provide an image generation method using this recording element.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a laser recording element comprising a base having a dye layer containing an image dye dispersed in a polymer binder, wherein the dye layer is incorporated in the dye layer. Having an infrared absorbing material in one or an adjacent layer, wherein the base comprises a composite film laminated on at least one side of the support, wherein the dye layer is on the composite film side of the base, And the composite film is a composite film comprising at least one substantially non-porous thermoplastic surface layer on a micro-porous thermoplastic core layer adjacent to the dye layer. This is achieved by the present invention in terms of elements.

[0008]

DETAILED DESCRIPTION OF THE INVENTION Any visible image dye can be used in the laser recording element of the present invention, provided that it can be removed by the action of a laser.
For example, the following dyes:

[0009]

Embedded image

[0010]

Embedded image

Alternatively, US Pat. No. 4,541,830
Nos. 4,698,651, 4,695,287
Nos. 4,701,439 and 4,757,046
Particularly good results have been obtained using the dyes described in JP-A Nos. 4,743,582, 4,769,360 and 4,753,922. These dyes can be used alone or in combination. These dyes can have a coverage of about 0.05 to about 1 g / m ² and are preferably hydrophobic.

Another aspect of the invention is to provide a laser exposure through the dye side of the element, imagewise heating of the recording element by means of a laser, and imagewise dyeing to obtain a dye image on the recording element. A method of forming a dye image comprising removing. In yet another aspect of the invention, the dye is removed imagewise by means of an air flow, reduced pressure and filter system.

[0013] The laser recording element of the present invention can be used for medical imaging,
It can be used for a reprographic mask, a print mask, and the like. The resulting image can be a positive or negative image. The dye removal process can be either a continuous image (photographic) or a halftone image. As a binder of the recording element used in the present invention,
Any polymeric material can be used. For example, cellulose derivatives (eg, cellulose nitrate, cellulose acetate hydrogen phthalate, cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose triacetate, hydroxypropyl cellulose ether, ethyl cellulose ether, etc.); polycarbonates; polyurethanes; polyester Classes; polyvinyl acetate; polystyrene; poly (styrene-co-acrylonitrile); polysulfone; polyphenylene oxide; polyethylene oxide; poly (vinyl alcohol-co-acetal).
[For example, polyvinyl acetal, poly (vinyl alcohol-co-butyral) or polyvinyl benzal]; or a mixture or copolymer thereof can be used. About 0.1 to about 5 g of the binder
/ M ² .

In a preferred embodiment, the polymeric binder used in the recording element used in the process of the present invention is at least as determined by size exclusion chromatography, as described in US Pat. No. 5,330,876. It has a polystyrene equivalent molecular weight of 100,000. If desired, a barrier layer can be used in the laser recording element of the present invention, as described in US Pat. No. 5,459,017.

To obtain a laser-guided image according to the present invention, it requires a small size, low cost, stability, reliability,
It is preferable to use a diode laser, such as an infrared diode laser, because it offers substantial advantages in terms of durability and ease of adjustment. In practice, prior to heating the recording element with an infrared laser, the element is treated with a cyanine infrared absorbing dye as described in U.S. Pat. No. 5,401,618, or the following U.S. Pat. : 4th, 94th
No. 8,777, No. 4,950,640, No. 4,95
No. 6,639, No. 4,948,776, No. 4,94
No. 8,778, No. 4,942,141, No. 4,95
No. 2,552, No. 5,036,040, and No. 4,9
It must contain an infrared absorbing material such as the other materials described in US Pat. No. 12,083.

The laser radiation is then absorbed by the dye layer and converted to heat by a molecular process known as internal conversion. Thus, the useful dye layer structure depends not only on the hue, transferability and strength of the image dye, but also on the ability of the dye layer to absorb the radiation and convert it to heat. The infrared absorbing dye may be included in the dye layer itself, and may be combined with another layer (ie, a layer above or below the dye layer).
May be included. Laser irradiation in the process of the present invention is preferably performed through the dye side of this recording element,
This allows the process to be a single sheet process (ie, without the need for a separate receiving element).

The dye layer of the laser recording element used in the present invention may be coated on a support or printed thereon by a printing technique such as a gravure process or a hopper coater. Composite films are commonly used because of their relatively low cost and good appearance, and are referred to in the industry as "packaging films." The support can include cellulose paper, polymer film or synthetic paper.

A packaging film having micropores, different from synthetic paper material, can be laminated on one side of many supports and still exhibit excellent curl properties. The curl properties can be controlled by the beam strength of the support. As the thickness of the support decreases, the girder strength also decreases. These films can be laminated to one side of a support of much lower thickness / lower girder strength and show little curl.

A composite package having micropores by simultaneously extruding a core layer and a surface layer and then performing biaxial stretching to form pores around a pore-inducing substance contained in the core layer. Film is conveniently manufactured. Such composite films are described, for example, in US Pat. No. 5,244,861.
In the specification. The core of the composite film is 15 to 95% of the total film thickness, preferably 30 to 85% of the total film thickness. Therefore, the skin (or a plurality of skins) having no pores has a total film thickness of 5 to 8
5%, preferably 15-70%. The density (specific gravity) of this composite film is between 0.2 and 1.0 g / cm3.
Preferably it is between 0.3 and 0.7 g / cm3. Core thickness is less than 30% or specific gravity 0.7g / c
Above m3, the composite film begins to lose useful compressive and thermal insulation. When the core thickness is greater than 85% or the specific gravity is less than 0.3 g / cm @ 3, the composite film becomes difficult to manufacture due to a decrease in tensile strength and becomes more susceptible to physical damage. The total thickness of the composite film can range from 20 to 150 μm, preferably 30 to 70 μm. Below 30 μm, the microporous film cannot be thick enough to minimize the inherent non-planarity of the support and will be more difficult to manufacture. At thicknesses above 70 μm, little improvement in either print homogeneity or thermal efficiency is seen, and there is little reason to add material to further increase costs.

Classes suitable for the thermoplastic polymer for the core matrix polymer of the composite film include polyolefins, polyesters, polyamides, polycarbonates, cellulose esters, polystyrene, polyvinyl resins, polysulfonamides, polyethers,
Polyimides, polyvinylidene fluoride, polyurethanes, polyphenylene sulfides, polytetrafluoroethylene, polyacetals, polysulfonates, polyester ionomers, and polyolefin ionomers are included. Copolymers of these polymers and / or mixtures of these polymers can also be used.

Suitable polyolefins include polypropylene, polyethylene, polymethylpentene, and mixtures thereof. Polyolefin copolymers, including copolymers of ethylene and propylene, are also useful. The composite film can be made using the skin (s) of the same polymeric material as the core matrix, or can be made using the skin (s) of a polymer composition different from the core matrix.
For compatibility, an auxiliary layer can be used to promote the adhesion of this skin layer to the core.

[0022] Additives may be added to the core matrix to improve the whiteness of these films. This includes processes known in the art, including adding a white pigment such as titanium dioxide, barium sulfate, clay or calcium carbonate. It also includes a fluorescent brightener or fluorescent agent that absorbs energy in the UV region and emits light sufficiently in the blue region, or other additives that improve the properties of the composite film or the productivity of the composite film. It is included.

Coextrusion, quenching,
Stretching and heat setting can be accomplished by any method known in the art for producing stretched films, such as by a flat film process or a foaming or tubular process. In the flat film process, the formulation is extruded from a slit die and the extruded web is quenched on a cooled casting drum to reduce the film core matrix polymer component and skin portion (s) to their glass transition temperature (Tg). )
It is necessary to quench below. The quenched film is biaxially stretched by stretching in a direction perpendicular to each other at a temperature above the glass transition temperature of the matrix polymer and the skin polymer. After stretching this film in one direction, it may be stretched in a second direction,
Or you may stretch simultaneously in two directions. After stretching the film, it is heat set in both stretching directions by heating to a temperature sufficient to crystallize the polymer, while suppressing some shrinkage of the film.

Having at least one non-porous skin on the micro-porous core increases the tensile strength of the film and improves manufacturability. It allows the film to be wider and the draw ratio greater than if the film were made entirely of layers with holes. Co-extrusion of multiple layers can further simplify the manufacturing process.

In the case of the base of the recording element of the present invention, the support on which the composite film having micropores is laminated may be a polymer support, a synthetic paper support, or a cellulose fiber paper support or a laminate thereof. Can be. Preferred cellulosic fibrous paper supports include U.S. Patent No. 5,250,4.
No. 96 is included. When a cellulose fiber paper support is used, it is preferable to extrude and laminate a composite film having micropores using a polyolefin resin. In order to minimize the curl of the resulting laminated support, it is desirable to keep the microporous packaging film tension at a minimum during the lamination process. Also, the back side of the paper support (i.e., opposite the composite film having microvoids) can be extrusion coated (e.g., about 10-75 g / m < ² >) using a polyolefin resin layer. 5,011,814 and 5,
It may also include a backing layer as described in US Pat. No. 096,875. High humidity applications (relative humidity 50%
For more than) about 30 to 75 g / m ^2, more preferably giving backside resin coverage of 35~50g / m ^2, it is desirable to keep curl to a minimum.

In one preferred embodiment, a relatively thick paper support (eg, at least 120 μm thick, preferably 120-250 μm thick) and a relatively thin microstructure are used to produce a recording element having the desired photographic appearance and feel. Composite package film having pores (for example, 50 μm
m, preferably 20 to 50 μm, more preferably 30 to 50 μm).

In another aspect of the present invention, a relatively thin paper or polymer support (eg, for inclusion in a printed multi-page document) to create a recording element resembling plain paper is provided. , Less than 80 μm, preferably 25-80 μm), to a relatively thin microporous composite packaging film (eg, less than 50 μm, preferably 20-50 μm, more preferably 30 μm).
厚 50 μm thick).

The following examples further illustrate the invention.

[0029]

EXAMPLES Preparation of a Base A with Micro Voids , Base A A commercially available packaging film (OPPalyte® 350,
Mobil Chemical Co.) was laminated to a paper support. OPPalyte
The 350 TW comprises a microporous stretched polypropylene core (approximately 73% of the total film thickness) with a microporous stretched polypropylene layer colored on both sides with titanium dioxide. Composite film (38 μm
Thickness) (d = 0.62), and the porogen is polybutylene terephthalate.

[0030] These packaging films can be laminated to the paper support in various ways (extrusion, compression, or other means). At present they were extrusion laminated with a colored polyolefin onto a paper support, as described below. This colored polyolefin is
Polyethylene (12 g / m ² ) containing anatase (titanium dioxide) (12.5% by weight) and benzoxazole optical brightener (0.05% by weight).

The paper support has a thickness of 137 μm and is made of Pontiac Maple 51 (a bleached maple hardwood kraft having a load average fiber length of 0.5 μm: Consolidated Pontia).
c, Inc.) and Alpha Hardwood Sulfite (bleached red hank wood hardwood sulfite with an average fiber length of 0.69 μm: from Weyerhauser Paper Co.). The back side of the paper support was coated with high density polyethylene (30 g / m ² ).

Base without microvoids, base B
Preparation of (Control) A support without microvoids was prepared by extrusion coating a colored polyolefin onto a paper support. The colored polyolefin is anatase (titanium dioxide) (1
Polyethylene (12 g / 2.5% by weight) and a benzoxazole optical brightener (0.05% by weight).
m ² ). The paper support was the same as described above. The back side of the paper support was coated with high density polyethylene (30 g / m ² ).

Laser dye ablative layer The following mixture was prepared and stirred until dissolved: cellulose nitrate (Hercules) 12 g IR-1 0.24 g Cyan-2 0.24 g as shown above Acetone 70 g

[0034]

Embedded image

Element 1 The above solution was applied to the above paper base A at 34 g / m ² (wet coverage). Control 1 Same as Element 1 except Base B was used instead of Base A. After laser exposure and drying, the element is subjected to a Spectra Diode with a maximum output of 600 mW / beam at 830 nm, 1000 rev / min
Exposure was performed using a Labs Lasers Model SDL-2432 and a spot size of about 12 μm × 25 μm using a lethe type printer with a drum circumference of 53 cm. A diode laser beam was scanned across the surface of the element to achieve 945 lines / cm (2400 lines / inch). A stream of air with a vacuum and filter system was blown over the donor surface to remove the ablated material.

Step tablet images were printed in successive patches with linearly decreasing laser intensity from maximum to zero. X-Rite Model 3
Measured using a 10 reflection densitometer. Each reading was based on an uncoated paper support. The results are shown in Table I below. As shown in step 21, a closely matching Dmax value indicates that the coating thickness is the same within experimental error.

[0037]

[Table 1]

The above results show that the base with microvoids (element 1) is more efficient than control 1 using a base without micropores (substantially lower Dmin (steps 1-5)).
Is shown). In addition, 0.03 on Dmin (element 1
By defining the speed point as the exposure required to print to step 10 in the case of control 1 and to step 7) in the case of control 1, as can be seen from the data in the table, the base having micropores can improve the speed. Gave. The speed point for element 1 is 498 mJ / cm ² , while the speed point for control 1 is 546 mJ / cm ^2.
/ Cm ² . Thus, the exposure to achieve this speed point is 9% less for Element 1.

[0039]

According to the laser recording element of the present invention,
The minimum density and sensitivity are improved.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-149063 (JP, A) JP-A-7-149065 (JP, A) JP-A-7-149066 (JP, A) JP-A-7-149 257056 (JP, A) JP-A-5-246453 (JP, A) JP-A-5-246164 (JP, A) JP-A-2-252580 (JP, A) JP-A-2-253988 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B41M 5/26

Claims (1)

(57) [Claims] 1. A laser recording element comprising a base having a dye layer containing an image dye dispersed in a polymer binder, wherein the dye layer is in or adjacent to the dye layer.
Has Sonia Ru infrared-absorbing material, wherein the base comprises a composite film laminated on at least one side of the support, said dye layer is in the composite film side of said base, and said composite film but the dye layer adjacent to, at least one layer of substantially laser recording element is a composite film comprising no thermoplastic surface layer micropores on the thermoplastic core layer having a microporous.