KR102175754B1 - Transparent doner film for laser-induced thermal imazing - Google Patents

Abstract

In the present invention, in the donor film for laser transfer in which a base film, a light-to-heat conversion layer and an intermediate layer are stacked, the light-to-heat conversion layer includes a light absorber as a single coating layer, and the maximum absorption wavelength of the light absorber is 780-1500 nm, It provides a transparent donor film, characterized in that the visible light transmittance of the entire film is 50% or more.

Description

Transparent donor film for laser thermal transfer {TRANSPARENT DONER FILM FOR LASER-INDUCED THERMAL IMAZING}

The present invention relates to a transparent donor film for laser thermal transfer, and more particularly, by using a diimmonium salt-based dye as a light absorber for photothermal conversion, the optical density for the near-infrared wavelength is high, and the light transmittance in the visible region is high. It relates to a high transparency donor film for laser thermal transfer.

Carbon black, dyes, pigments, and metal materials are used as light-heat absorbers used in donor films for laser-induced thermal imaging (LITI). Among them, the dye has a maximum optical density in the near-infrared range of 700-1500 nm, which is a typical laser wavelength range used for laser thermal transfer, while relatively low optical density in the visible range of 700 nm or less. It has the advantage of being able to choose a wide range of visible materials.

For example, in Patent Document 1, Prussian Blue (Prussian Blue, or Pigment Blue 27), copper phthalocyanine (Pigment Blue 15), metal dithiolene, as an image forming radiation absorber material suitable for use in an 808 nm laser, And polymethine dyes, cyanine dyes, and the like.

Meanwhile, in Patent Document 2, a dye that can be applied to a photothermal conversion layer having a maximum optical density of the photothermal conversion layer at a wavelength of 650-1200nm is 3 times larger than the maximum optical density of the photothermal conversion layer at a wavelength of 400-650nm. As an example, indolium salts or benzoindolium salts (benz[e]indolium salts) series of dyes are disclosed.

<Patent Document 2, Examples of benzoindolium salt>

Patent Document 3 discloses a metal complex compound of a phthalocyanine-based compound as a light absorber for laser thermal transfer.

<Patent Document 3, Phthalocyanine-Metal Complex>

However, when the dyes are used, the transmittance in the visible light region is insufficient, and thus, difficulties in quality inspection of the manufactured donor film or alignment with the receiver element continue.

Republic of Korea Patent Publication No. 2009-0034364 Republic of Korea Patent Publication No. 2007-0067725 U.S. Patent No. 6,066,729

It is an object of the present invention to provide a transparent donor film for laser thermal transfer, which has a high optical density for near-infrared wavelengths and a light transmittance in the visible region that is significantly higher than those manufactured using conventional dyes.

In the present invention, in the donor film for laser transfer in which a base film, a light-to-heat conversion layer and an intermediate layer are stacked, the light-to-heat conversion layer includes a light absorber as a single coating layer, and the maximum absorption wavelength of the light absorber is 780-1500 nm, It provides a transparent donor film, characterized in that the visible light transmittance of the entire film is 60% or more.

The light absorber may be a diimmonium salt-based compound represented by the following formula:

[Formula 1].

The content of the organic dye in the light-to-heat conversion layer is preferably 5-15% by weight based on the solid content.

It is preferable that the standard deviation of the optical density for each portion of the donor film is 10% or less.

By using an organic dye that absorbs light of the same wavelength as the infrared laser wavelength used for phosphor transfer as the light-to-heat conversion layer material of the donor film, the transmittance of the donor film in the visible region could be increased, and the inner film by using a high-transmission donor film. There is an advantage in that it is possible to more easily identify the cause of defects in phosphor patterning by facilitating foreign matter inspection. In addition, due to the dispersion problem in the resin generated when the inorganic light-to-heat conversion material is used, a difference in the amount of heat transferred to the phosphor may occur due to the variation in heat generated according to the dispersion density, and this may cause a problem that the surface of the transferred phosphor becomes rough. The organic dye used in is characterized in that there is no problem of dispersion because it is completely dissolved in the resin.

1 is a schematic cross-sectional view of a donor film 10 for laser thermal transfer of the present invention.

Hereinafter, a donor film for laser thermal transfer of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view of a donor film 10 for laser thermal transfer of the present invention. The donor film 10 for laser thermal transfer of the present invention is a base film 11, a photothermal conversion layer 12, and an intermediate layer 13 are sequentially stacked, and the photothermal conversion layer 12 is a single coating layer and a light absorbing agent. Including, but the maximum absorption wavelength of the light absorber is 780-1500 nm, characterized in that the visible light transmittance of the entire film is 50% or more.

Base film (11)

The base film 11 includes other layers having functionality in a series of processes of removing the donor film from the receiver after manufacturing of the donor film, assembly with the receiver, and transfer, for example, other layers of the donor film of the present invention. It functions as a substrate supporting the light-to-heat conversion layer 12, the intermediate layer 13, and a transfer layer (not shown) stacked on the intermediate layer.

The base film 110 may be typically a polymer film. One suitable type of polymeric film is a polyester film having both light transmission and heat stability, for example polyethylene terephthalate or polyethylene naphthalate film. However, it is possible to use other films with sufficient mechanical and thermal stability for certain applications, and, optionally, sufficient optical properties, including high transmittance of light of a particular wavelength.

The polymer polymer suitable for the base film 100 includes, for example, polycarbonate, polyolefin, polyvinyl resin, or polyester. In one embodiment according to the invention, synthetic straight-chain polyester is used for the support layer.

Typical thickness of the support layer may be in the range of 0.005 to 0.5 mm.

The polymeric polymer film used for the base film is a different composition, specifically, primer treatment, roughness (roughness) treatment for the purpose of improving adhesion with the light-to-heat conversion layer, or stretching or heat treatment, water repellent treatment for thermal stability, or In order to control the transmittance of light, it may contain a small amount of fine particles or fillers, or may be water-repellent treatment. In addition, substrates disclosed in Korean Patent Publication Nos. 2007-0067725, 2007-0049003, 2004-0101053, etc. may be referred to for the base film applied to the donor film of the present invention.

Photothermal conversion layer (120)

The light-to-heat conversion layer 120 absorbs light (laser) by one or more light absorbers included therein while transferring the transfer material to the receiver using the donor film 110 and converts it into heat, so that the transfer layer 140 Some or all of the components that form the supply power to be transferred to the receiver. The power may be heat itself, or may be a physical force due to thermal expansion of some layers.

Typically, the light absorber of the LTHC layer absorbs light in the infrared, visible, and/or ultraviolet regions of the electromagnetic spectrum and converts the absorbed light into heat. The light absorber may be one that absorbs light of a specific wavelength or wavelength region used for transfer highly, but absorbs much less light (transmitted or reflected) for other wavelength regions or specific wavelengths.

The light-to-heat conversion layer is usually manufactured as thin as possible in terms of local absorption of heat being advantageous for high-resolution transfer, and a thickness of 10 to 500 nm is usually used.

On the other hand, the light absorber used in the light-to-heat conversion layer of the donor film for laser thermal transfer of the present invention is advantageous for high-resolution transfer when a material having a high absorbency for light used for transfer is used. However, photothermal conversion by a light absorber means light absorption for a specific wavelength, and accordingly, a donor film including a photothermal conversion layer to which a light absorber is applied becomes an obstacle to inspection during manufacture. For example, the inspection of the donor film can be performed using a defect detector. In the case of inspection in the reflection and transmission mode, foreign matter and coating defects on the film surface are detected in the reflection mode, and in the case of transmission mode, the film Internal foreign matter is detected. When the existing carbon black is used as a light-to-heat conversion material, the transmittance is remarkably low, making it difficult to identify foreign substances in film inspection using the transmission mode.

An organic dye having a maximum absorption wavelength of 780-1500 nm may be used as the light absorbing agent applied to the light-to-heat conversion layer 12 of the transparent donor film 10 of the present invention. As an organic dye having a maximum absorption wavelength in the above wavelength range, preferably, a dye of diimmonium salts represented by the following formula (1) is used:

[Formula 1]

In the above formula, R1-R8 are each independently selected from the group consisting of an alkyl group, an alkylene group, a cyanoalkyl group, a hydroxyl group, an alkyl sulfonic acid group, an alkylnitro group, an allyl group, and a phenylaryl group, wherein at least one of R1-R8 is At least one hydrogen atom is substituted with a halogen atom; A ^- can be a carboxylic acid anion or a monovalent or divalent inorganic acid anion.

As the substrate used for the transparent donor film, a PET film having a thickness of 0.005 to 0.5 mm is used, and in the case of 100 μm, the visible light transmittance of the biaxially stretched PET film is about 90%. Even when this is used as a base film, it was confirmed that when the light absorber of Formula 1 is used, a transparent donor film having a visible light transmittance of 50% or more can be prepared while maintaining the transfer performance.

In theory, the visible light transmittance of the donor film is inversely proportional to the concentration of the light absorbing agent used in the light-to-heat conversion layer. As a non-limiting intention, the diimmonium salt-based organic dye used as the light absorbing material in the present invention is superior to other organic dyes in the near-infrared, specifically 780-1500 nm wavelength range, whereas the optical density in the visible range Due to its low density, it is interpreted that the efficiency of photothermal conversion by near infrared rays is high, while the transparency in the visible region can be maintained at a high level.

2A is an absorption spectrum for visible-near-infrared rays of the diimmonium salt used as a light absorber in the present invention, and FIG. 2B is an absorption spectrum for visible-near infrared rays of carbon black widely used as a light absorber. 2A and 2B, it can be seen that the diimmonium salt as a light absorbing agent exhibits a low optical density, that is, a high transmittance, in the visible region, and a high optical density in the near-infrared region. On the other hand, the donor film of Comparative Example 1 using a carbon black pigment showed a high optical density in the visible light region, and the transmittance measurement result showed a value of 5% or less.

The above-described diimmonium salt-based dye has excellent solubility in organic solvents. Such solubility in a solvent is essential for effective dispersion of the light absorber, and it can act as an advantage in that it is possible to reduce the difference in the amount of heat transferred to the phosphor due to the variation in heat generated according to the dispersion density due to dispersion problems in the resin. The dispersibility acts as an additional advantage of reducing the thickness deviation of the photothermal conversion layer having a thin thickness of 10 μm or less.

The light absorbing agent may be used together with a binder to control adhesion to another layer, for example, the base substrate 110 and/or the interlayer 130. Preferred binders are those that exhibit good compatibility with the light absorber and allow more radiation absorbers to be included in the transfer auxiliary coating layer without significantly losing the adhesion of the transfer auxiliary coating to the substrate layer. The binder is usually a high molecular polymer or copolymer. For example, acrylic resins (polyacrylate, polymethacrylate, polyacrylic acid, or copolymers of these and polyolefins, which may or may not have hydrophilic functional groups such as -OH or -COOH), sulfonated Or non-sulfonated polyester resins, polyurethanes, polyvinyl alcohol-based resins (eg, PVA, EVA, etc.), polyolefins, and fluorine-based resins (PTFE, PCTFE, etc.).

The above-described light absorber and the binder are made of an aqueous or oil-based coating agent, and are laminated by coating the base substrate 110. At this time, the content of the light absorber is typically in the range of 5 to 85% by weight, preferably 5 to 60% by weight of the solid fraction of the coating composition.

In addition to the coating composition, a crosslinking agent, a moisturizing agent, a surfactant, a pH adjusting agent, a viscosity adjusting agent, and a co-solvent may be added.

It is preferable that the thickness of the photothermal conversion layer is 1-5 μm. If the thickness of the light-to-heat conversion layer to which the immonium salt dye is applied does not reach 1 μm, it may be difficult to adjust the appropriate optical density, and when it exceeds 5 μm, it is difficult to cure the dye-containing resin.

Middle layer(13)

The intermediate layer 13 prevents contaminants generated by high heat generated in the process of converting light (laser) incident from the outside into heat by the light absorber from moving to the transfer layer, thereby transferring from the transfer layer to the receiver. It is a layer provided for the purpose of minimizing damage, contamination, and deformation of the resulting image. In general, the intermediate layer is preferably a polymer film capable of blocking the decomposition material of the light-to-heat conversion layer and transfer to the transfer layer while minimizing the loss of heat generated in the light-to-heat conversion layer. On the one hand, the intermediate layer must have thermal stability that is not melted or pyrolyzed by heat generated in the photothermal conversion layer, on the other hand, and on the other hand, it must be formed through a process such as a phase change of the film when it reaches a specific temperature. This is required at the same time.

A typical material constituting the intermediate layer is a polymer film. The material of the polymer film may be thermoplastic or thermosetting. Organic materials suitable as intermediate layer materials include both thermosetting (crosslinkable) and thermoplastic materials. In all cases, the material selected for the interlayer must be forming a film and must remain substantially intact during the transfer process. This can be achieved by selection of suitable materials based on their thermal and/or mechanical properties. As a guideline, the Tg of thermoplastics should be greater than 150°C, preferably greater than 180°C.

Specific examples of the thermosetting resin include poly(meth)acrylate, polyester, epoxy, and polyurethane. These are usually laminated in such a way that they are coated with a photothermal conversion layer in the form of a precursor and then crosslinked to form a predetermined crosslinked intermediate layer.

On the other hand, examples of the thermoplastic resin include polysulfone, polyester, polyamide, and the like. Such a thermoplastic organic material may be laminated on the light-to-heat conversion layer through a known method such as a conventional solvent coating.

In the case of an intermediate layer composed of a polymer film, in the case of an intermediate layer including an organic material, a photoinitiator, a surfactant, a pigment, a plasticizer, a coating aid, and the like may be included.

The optimum thickness of the polymer film applied to the intermediate layer may vary depending on each material, and is usually in the range of 0.05-10 μm.

Another type of material that makes up the intermediate layer is a film made of a typical material of a metallic material. Suitable metallic materials include metals, metal oxides, metal sulfides, inorganic carbon coatings and the like, which materials have high transmittance or reflectivity at the wavelength of the image laser. Such a material may be formed on the photothermal conversion layer through conventional techniques (eg, vacuum sputtering, vacuum evaporation, plasma jet, etc.). In the case of an intermediate layer made of a metallic material, the thickness is typically 0.01 μm-10 μm.

In addition, for the material and structure applied as an intermediate layer of the donor film of the present invention, Korean Patent Laid-Open Publication Nos. 2000-0005446, 2006-0020029, 2007-0096082, 2007-0107527, 2005-0063534 , 2008-0085553, 2007-0059725, 2007-0024285, 1998-0037999, and the like may be referred.

On the intermediate layer, at least one material (transfer material) transferred to the receiver is formed by laminating with or without a binder. When the transfer material is exposed to image generation light, all or part of the transfer material may be selectively transferred. Components of a single portion of the transfer layer can be selectively transferred while other components remain. The transfer layer, along with other elements that may or may not be patterned in a similar manner, is a color filter, black matrix, spacer, barrier, partition, polarizer, retardation layer, wave plate, organic conductor or semiconductor, inorganic conductor or Semiconductors, organic electroluminescent layers, phosphor layers, organic electroluminescent devices, organic transistors, and other elements that may be used in displays, devices, or those suitable for forming portions thereof.

Materials suitable for use as a transfer layer to be imagewise deposited on a receiver are well known in the art. The transfer layer may include an organic, inorganic, organometallic or polymeric material. Examples of materials that can be selectively patterned from a donor element as a transfer layer and/or as a material incorporated into the transfer layer include colorants (including pigments and/or dyes dispersed in a binder), polarizers, liquid crystal materials, particles (Including spacers for liquid crystal displays, magnetic particles, insulating particles, and conductive particles), light-emitting materials (including phosphors and/or organic electroluminescent materials), light-emitting devices (for example, electroluminescent devices) Light-receiving materials, hydrophobic materials (including partition banks for ink jet receptors), hydrophilic materials, multilayer stacks (e.g., multilayer device structures such as organic electroluminescent devices), microstructured or nanostructured layers, photos Resists, metals, polymers, tackifiers, binders and biomaterials, and other suitable materials or combinations of materials. In one embodiment, the transfer layer comprises one or more materials useful for display applications, particularly color filter manufacturing.

Typically, the transfer layer contains a suitable binder and may also contain trace amounts of radiation absorbing agents, surfactants or other additives. Other optical additives include dispersants, UV-stabilizers, plasticizers, crosslinkers, coating aids and tackifiers.

Regarding the structure of the transfer layer applicable to the present invention and the transfer material, additionally, Korean Patent Publication Nos. 2006-0030405, 2009-00779287, 2005-0050492, 2003-0077646, 2005-0082952, 2007-0111702, 2010-0024672, 2004-0054474, 2005-0052272, 2006-0019451, 2006-0025018, 2010-0091430, 2002-0064302, etc. You can refer to it.

The donor film of the present invention, that is, the total visible light transmittance (% transmittance) of the donor film including the base film, the photothermal conversion layer and the intermediate layer is 50% or more, preferably 60% or more. When the visible light transmittance is 50% or less, the transmittance is low, and there is a problem in detecting foreign matter inside the film.

Hereinafter, the configuration of the present invention and effects thereof will be described in more detail through examples and comparative examples. The present examples are for explaining the present invention more specifically, and the scope of the present invention is not limited to these examples.

Example One

Substrate layer: Toray Advanced Materials' XG Series PET film was used as the substrate film (thickness 100㎛; light transmittance of 550nm wavelength (%-transmittance) 9+0%).

Photothermal conversion layer crude liquid: Diimmonium salt dye A (Kyungin Corporation, NIR1000A) A photothermal conversion layer crude liquid containing 30% by weight of a solid content including a photoinitiator, a dispersant, an acrylic UV curing resin, and an epoxy binder was prepared. The content of the diimmonium salt dye A was 15% by weight based on the total solid content.

Photoinitiator-(2% by weight compared to UV curing resin, made by BASF / IRGACURE OXE02)

Dispersant-(0.001% by weight based on total solids, BYK-CHEMIE/ BYK-333)

Acrylic UV curing resin-(10% by weight of total solids, SARTOMER/CN996)

Epoxy binder-(5% by weight based on total solids SARTOMER/CN120C80)

Solvent-MEK,PGMEA (50:50)

Intermediate layer crude liquid: To protect the light-to-heat conversion layer, an acrylic resin containing TMPTA (trimethylolpropane triacylate), a photoinitiator, and a protective layer crude solution of 25% by weight based on solids including a binder was prepared.

Preparation of donor film: A photothermal conversion layer crude solution was applied on a base film using a Mayer bar, and then cured by a UV curing method using a mercury lamp to form a photothermal conversion layer coating film having an average thickness of 2.5 μm. Thereafter, the intermediate layer crude solution was applied in the same manner and UV cured to form an intermediate layer having the same thickness as the photothermal conversion layer.

Example 2

A donor film was prepared in the same manner as in Example 1, except that the crude solution of the photothermal conversion layer was prepared so that the content of the diimmonium salt dye A was 11% by weight based on the total solid content.

Example 3

A donor film was prepared in the same manner as in Example 1, except that the crude solution of the light-to-heat conversion layer was prepared so that the content of the diimmonium salt dye A was 7% by weight based on the total solid content.

Example 4

A donor film was prepared in the same manner as in Example 1, except that a light-to-heat conversion layer crude solution containing 15% by weight of the total solid content was prepared using dye B (Kyungin Corporation, NIR1000B) as a diimmonium salt dye. .

Example 5

A donor film was prepared in the same manner as in Example 4, except that a light-to-heat conversion layer crude solution containing 11% by weight of a dye was prepared using dye B as a diimmonium salt dye.

Example 6

A donor film was prepared in the same manner as in Example 4, except that a light-to-heat conversion layer crude solution containing 7% by weight of a dye was prepared using dye B as a diimmonium salt dye.

Comparative example One

The same as in Example 1, except that the photothermal conversion layer crude liquid was prepared so that the carbon black content was 15% by weight based on the solid content by using carbon black (manufacturer, product number; simple feature) instead of the diimmonium salt dye as the light absorbing agent. A donor film was prepared.

evaluation

1. Optical density

Optical density (OD) was calculated by measuring the transmittance (%) at 980 nm using UV3600 (manufactured by Shimadzu Corporation), and substituting the value into the following equation.

Optical density (OD) = -log ₁₀ (1/T _o )

T _o = transmittance (%)

The deviation of the optical writing degree was calculated by measuring the optical degree and degree by the above method at an arbitrary minimum of 10 points, and then calculating the difference between the minimum value and the maximum value from the average value.

2, surface roughness

It was measured using a three-dimensional contact roughness meter (Kosaka, SE3300). Each measurement was performed three times, and the average value was calculated.

The measurement results of the donor films prepared in the above Examples and Comparative Examples are summarized in the table below.

Transmittance (%)
(@550nm) Optical density
(@980nm) Optical density deviation Surface roughness
Ra(nm) Example 1 60 0.6 ±0.02 0.3 Example 2 75 0.4 ±0.02 0.3 Example 3 81 0.2 ±0.01 0.2 Example 4 76 1.3 ±0.02 0.3 Example 5 80 1.1 ±0.01 0.2 Example 6 83 0.9 ±0.01 0.2 Comparative Example 1 5 1.2 ±0.1 0.9

As the amount of organic dye was increased, it was found that the optical density at the laser transfer wavelength (980 nm) increased, but the transmittance in the visible light region was also decreased.

When the organic dye A was used, the molar absorption coefficient in the infrared region was low, and when 15% of the dye was used, the optical density was relatively low of 0.6, and the transmittance was about 60%.

When using organic dye B, the optical density is higher than that of A, and when 15% of the solid content is used, the optical density is 1.3 and transmittance is 76%. When the amount of dye is reduced to 11%, the transmittance of the visible light region of the film It was confirmed that it can be made more than 80%.

In Comparative Example 1, it can be seen that when the structure of a general donor film to which carbon black, which is an inorganic material, is applied as a material for the light-to-heat conversion layer, and the optical density is 1.2, the transmittance in the visible light region is significantly reduced to about 5%.

On the other hand, it can be seen that if the amount of dye is more than 15% of the solid content, the surface of the prepared donor film becomes rough due to the solubility of organic dyes, making it difficult to serve as a donor film.

10.. donor film 11.. base layer
12..Photothermal conversion layer 12.. Intermediate layer

Claims (5)

In the donor film for laser transfer in which a base film, a photothermal conversion layer and an intermediate layer are laminated,
The light-to-heat conversion layer includes a light absorber as a single coating layer, wherein the light absorber is an organic dye, the content of the organic dye is 11 to 15% by weight based on the solid content, and the maximum absorption wavelength is 780-1500 nm,
The intermediate layer is formed by including an acrylic resin containing TMPTA (trimethylolpropane triacylate), a photoinitiator, and a binder,
Transparency donor film, characterized in that the visible light transmittance of the entire film is 50% or more. delete The transparent donor film according to claim 1, wherein the organic dye is a diimmonium salts-based dye represented by Formula 1 below:

In the above formula, R ₁ -R ₈ are each independently selected from the group consisting of an alkyl group, an alkylene group, a cyanoalkyl group, a hydroxyl group, an alkyl sulfonic acid group, an alkylnitro group, an allyl group, and a phenylaryl group, wherein R ₁ -R ₈ At least one of which is one in which one or more hydrogen atoms are substituted with a halogen atom; A ^- is X is a carboxylic acid anion or a monovalent or divalent inorganic acid anion. delete The transparent donor film according to claim 1, wherein a standard deviation of an optical density (OD) of each portion of the donor film is 10% or less.

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