KR19990087703A - Inkjet recording media - Google Patents

Abstract

The present invention relates to an inkjet recording medium comprising a hydrophilic microporous polymer film and a hygroscopic layer present on its main surface. The hygroscopic layer receives the inkjet image and the hydrophilic microporous polymer membrane diffuses water and other solvents from the ink to provide a rapid dry and accurate inkjet image. The present invention also discloses a method of forming an accurate ink jet image using a conventional ink jet printer using the disclosed ink jet recording medium. Applications for inkjet recording media range from overhead projector slides to graphic appliques such as outdoor billboards. A second embodiment is to provide a pressure sensitive adhesive region on at least a portion of the hydrophilic microporous polymer membrane face opposite the hygroscopic layer containing an accurate permanent image.

Description

Inkjet recording media

Inkjet recording media are desirable for generating images from computer printers and the like for applications ranging from paper or desktop prints using overhead transparency stock to commercial graphic displays such as billboards and other outdoor advertising media.

Three approaches have been generally taken to produce inkjet media in an attempt to rapidly produce accurate images using both pigment and dye-based inks. All three of these approaches still have open flaws and problems.

The most basic approach has been to use paper as a receptor for inkjet images. In this case, the blank paper without ruled lines does not have high image density or shows accurate dot reproducibility because the dye or pigment contained in the solvent used in the ink jet ink diffuses into the pores of the paper. The result is an unprinted image of low resolution.

An improvement to this approach is the application of a coating on top of the paper, which acts to capture dyes and pigments on the surface. The hydrophilic coating or the hydrophilic coating layer easily accommodates inkjet images, and the solvent pushing the dye and pigment diffuses into the underlying paper. This improves the appearance of the image by improving color density and resolution. This layer mainly comprises a water soluble or water swellable layer and may comprise a hydrophilic filler such as silica. A recent reference to this is U.S. Patent 5,213,873.

However, although such media provide an acceptable degree of image quality, this presents all the inherent disadvantages of paper that lacks dimensional stability and sensitivity. The underlying paper is not durable and is particularly susceptible to curling or other deformation, especially due to the presence of large amounts of water in the ink or surrounding environment. The bending or shrinkage of hygroscopic expansion and contraction alone limits the use of paper for large multipanel graphics. Therefore, there is a limit in particular for outdoor use.

A second approach is to use inkjets, in which images are formed on transparent polymers or durable substrates to obtain slides. Many patent documents illustrate the use of an ink soluble layer in a transparent polymer material. Examples are US Pat. No. 4,935,307 and US Pat. No. 4,956,230. This layer mainly consists of a water soluble layer or a water swellable layer. One of the main problems when using such a material is that all ink carrier solvents remain in the hydrophilic coating since the base film does not absorb the water or liquid present in the inkjet ink. Therefore, the drying time increased to within 4 minutes. The result is a smooth or tacky surface prior to final drying. Improvements in clear coatings for images have been presented by Ikubal allies, including US Pat. No. 5,134,198 and US Pat. No. 5,219,928, in interpenetrating networks. When such materials are coated on a standard polymer film, the drying time is longer than desired even though faster than standard water soluble materials that provide a durable image.

Other recent studies have attempted to exclude bleeding and tackiness of hygroscopic coatings on polymer films. Examples thereof include various methods of preventing the adhesion by allowing the liquid to separate from the surface. This recent study relates to multilayers such as in US Pat. No. 4,379,804, US Pat. No. 5,192,617, and US Pat. No. 5,352,736, whereby the top layer delivers the solvent to the hydrophilic bottom layer. These systems work well, but require multiple coating treatments. In addition, all solvent entering the system must be discharged and evaporated on the same side of the incoming.

Primarily crosslinking agents can be used in hygroscopic coatings to prevent excessive sensitivity. This exchange method causes any decrease in moisture absorption resulting in loss of capacity of the coating to accommodate all the ink deposited on the surface without spreading the dots. Various processes that balance this property are disclosed in US Pat. No. 5,241,006, US Pat. No. 5,208,092, US Pat. No. 5,376,727 and US Pat. No. 4,904,519.

A third approach has been to use a hydrophilic porous polymeric support or polymer / paper fiber hybrid (without any other ink receptive coating or layer on the surface) to receive inkjet images directly. Such materials have dimensional stability but poor image density and resolution. Image drying time is very fast.

The hydrophilic porous polymer support readily accepts inkjet images, and the solvent comprising dyes and pigments diffuses into the support. However, this approach also leads to the diffusion of these solvents and to the diffusion of dyes and pigments, thus preventing the formation of accurate and clear images. Thus, a solution is provided in US Pat. No. 5,443,727 to prevent the diffusion of accurate images and to increase the apparent image density, which heats the support to decompose the porosity of the support and seals the image to the intended location. It costs. However, heating operations are particularly difficult for large graphics that must avoid shrinkage and crease formation.

The present invention relates to an ink jet recording medium for rapidly generating an accurate image.

1 is a cross-sectional view of a first embodiment of the present invention.

2 is a cross-sectional view of a second embodiment of the present invention.

3 is a micrograph of a cross section of a conventional hydrophilic microporous polymer membrane.

4 is a micrograph of an embodiment cross section of the present invention having a hydrophilic microporous polymer membrane having opposing sides and a hygroscopic layer present on at least one side of the membrane.

5 is a micrograph of a conventional hydrophilic microporous polymer membrane.

Figure 6 is a micrograph of an embodiment of the present invention having a hydrophilic microporous polymer membrane having opposing faces and a hygroscopic layer present on at least one side of the membrane.

Embodiments of the Invention

1 illustrates one embodiment of the present invention. The inkjet recording medium 10 is composed of a hydrophilic porous polymer membrane 12 and a hygroscopic layer 14 on its surface. Layer 14 may be coated on or laminated to film 12 using techniques known to those skilled in the art of lamination or coating of multilayer structures. Non-limiting examples of cladding or lamination techniques include notch bar cladding, curtain cladding, roll cladding, extrusion cladding, gravier cladding, calendering and the like.

Hydrophilic microporous polymer membrane 12 is hydrophilic and usually contains a water soluble solvent used in inkjet formulations. Microporous membranes can be used of various pore sizes, compositions, thicknesses and pore volumes. The microporous membrane suitable for the present invention has a proper pore volume to completely absorb the inkjet ink released in the hydrophilic layer of the inkjet recording medium. This void volume must be accessible to the inkjet ink. In other words, microporous membranes that do not include passages that connect the void sites to the hygroscopic surface coating or to each other (ie, independent bubble films) function similarly to films that have no voids without providing the benefit of the present invention.

The void volume is in accordance with ASTM D792 (1-volume density / polymer density) × 100 It is defined as If the density of the polymer is unknown, the pore volume can be determined by saturating the membrane with a liquid having a known density and comparing the weight of the saturated membrane with the weight of the membrane before saturation. Usually the pore volume of the hydrophilic microporous polymer membrane 12 will be 10 to 99%, often 20 to 90%.

The volume capacity of the membrane is determined by the void volume along with the membrane thickness. In addition, the film thickness affects the flexibility, durability and dimensional stability of the film. The membrane 12 may have a thickness of about 0.01 to about 0.6 mm (0.5 to about 30 mils) or more for normal use. The thickness is preferably about 0.04 to about 0.25 mm (about 2 to about 10 mils).

The liquid volume of a typical ink jet printer is about 40 to 140 picols per drop. Normal resolution is 118-283 droplets per cm. High resolution printers have a smaller dot volume. Substantial results show a deposition volume of 1.95-2.23 μl per cm 2, depending on the color. The solids application amount in the multicolor system provides a coating amount on the order of 300% (using undercolor removal) to provide a volume weld of 5.85-6.69 μl per cm 2.

The hydrophilic microporous polymer film 12 has a pore size smaller than the nominal droplet size of an ink jet printer in which an ink jet recording medium is used. The pore size may be from 0.01 to 10 μm, preferably from 0.5 to 5 μm, in one or more plane pores of the sheet.

The porosity or pore properties of the membrane 12 correspond not only to the overall thickness of the membrane, but also to a depth sufficient to produce the required pore volume. Therefore, the membrane can be asymmetric in nature, so that one side of the above-described properties can be obtained, and the other side can be somewhat less porous or nonporous. In this case, the porous side has an appropriate pore volume to absorb the liquid in the ink passing through the hygroscopic layer 14.

Non-limiting examples of hydrophilic microporous polymer membranes include polyolefins, polyesters, polyvinyl halides, acrylics, and the like, having microporous structures. Preferred are "deslin" microporous membranes commercially available from Fiji Industries, as defined in US Pat. No. 4,833,172, as described in US Pat. Nos. 4,867,881, 4,613,441, 5,238,618 and 5,443,727. There are hydrophilic microporous membranes used for filtration, printing or liquid barrier films. The Teslin microporous membrane had a total thickness of about 0.18 mm and a pore volume of 65.9% experimentally. The ink volume capacity of the film is 11.7 μl per cm 2. Thus, such a film will have sufficient pore volume with a thickness that completely absorbs the ink deposited by most inkjet printers, even considering the amount retained in the hygroscopic layer even in the application range of 300%.

Membrane 12 may optionally include various additives known to those skilled in the art. Non-limiting examples thereof include fillers such as silica, talc, calcium carbonate, titanium dioxide or other polymer inclusions. It may further include modifiers to improve coating properties, surface tension, surface finish, and hardness.

The hygroscopic layer 14 may be a coated layer or a stacked layer on a portion of the film 12, wherein an inkjet image is formed. Thus, layer 14 does not need to completely apply film 12. The layer 14 does not even have to apply both sides of the film 12. Layer 14 is substantially present on the surface of membrane 12 and preferably does not contact the inner void surface of the membrane. Depending on the end purpose for the medium 10, one or more faces of film 12 may be at least partially applied by layer 14, the other face being an antistatic coating, an adhesive, a blocking layer, a light blocking layer, It may be sealed or covered with other materials such as strength enhancing layers and the like.

Layer 14 may be constructed from a variety of natural or synthetic structured materials known to those skilled in the art for providing an ink receptive surface. Non-limiting examples of such materials used to form layer 14 include polyvinyl alcohol, polyvinyl pyrrolidone, cellulose derivatives such as carboxymethyl cellulose, polyethylene oxide, water soluble starch and gums and the like. In addition, inorganic fillers such as silica, talc, calcium carbonate, titanium dioxide can be useful for handling, improving opacity, strength, hydration or controlling viscosity. Mordant and color stabilizers, such as in US Pat. Nos. 5,354,813 and 5,403,955, may also be included.

Among these materials, hygroscopic polymer coatings are preferred because of their ease of manufacture and the ability to provide an ink receptive surface for permanent retention, contact, and receipt of dyes and pigments within accurate inkjet images. Of these coatings, poly (N-vinyl lactam), polyethylene oxide, methyl cellulose derivatives, propyl cellulose derivatives and poly (vinyl alcohol) are particularly preferred.

The hygroscopic layer 14 can be formed on the membrane 12 using a variety of techniques including coating, lamination or coextrusion. When the hydrophilic coating composition is applied to the film, the viscosity and concentration of the solution affects the performance of the resulting ink jet recording medium. For example, low viscosity coating solutions coated on membranes with very high porosity and / or large pore sizes tend to fill the pores so that the resulting coating membranes are saturated with hygroscopic polymers and contain little or no coating on the surface. Will not. Films coated in this way do not meet the requirements of the present invention, since the imaged media usually has low image density and contrast, and can dry much more slowly. Techniques for attaching the hygroscopic layer 14 on the membrane 12 are illustrated in this embodiment.

The solution viscosity of the coating solution is controlled by various factors including coating solvent, polymer solubility, polymer molecular weight, temperature and the like. For the present invention, a solution having an intrinsic viscosity of less than 100,000 as a low viscosity solution is measured using a device such as a Brookfield viscometer.

Layer 14 may be about 2 to 35 μm thick. It is preferable that the thickness is about 3-15 micrometers. Larger thicknesses cause the surface to become tacky and have the problem of drying out.

The combination of the membrane 12 and the layer 14 allows the generation of accurate images with fast drying time of about 15-30 seconds after printing.

Both the film 12 and the layer 14 may include various adhesives that will further improve the ink jet recording medium of the present invention.

The layer 14 itself is an anti-scratch composition such as silica filled acrylic polymer, moisture resistant or anti-fingerprint composition such as particulate filler, ultraviolet light absorbing composition such as benzophenone and handling aids such as Multi-layers having an outermost layer comprising a silicone or wax block and a surface wear aid. Therefore, the hygroscopic layer 14 may include mordant, ultraviolet light absorber, antioxidant, filler, surface abrasion aid, blocking aid or other material that improves image stability and handling.

Optionally, the medium 10 can include a backing layer covering the opposite major surface of the film 12 to reduce or minimize curling of the medium 10 after image formation. Non-limiting examples of back layer materials include materials having a similar hygroscopic expansion rate to layer 14. Such materials include starch, gum, and other water swellable polymers.

The medium 10 may comprise opposing major faces of the sealed film 12 due to saturated coating or other manufacturing method. Non-limiting examples of such processes include pressure sensitive adhesive coating, calendering, hot roll forming, coextrusion, lamination, and the like.

Optionally, the medium 10 after image formation can have the pore structure of the degraded film 12 to provide transparency by post-treatment such as heating or calendering as described in US Pat. No. 5,443,272.

2 illustrates a second embodiment of the present invention. The inkjet recording medium 20 is composed of a hydrophilic microporous polymer film 22 and a hygroscopic layer 24 on its surface. Film 22 and layer 24 correspond to film 12 and layer 14 of the embodiment described in FIG. 1, respectively. The medium 20 further includes a pressure sensitive adhesive layer 26 that applies at least a portion of the film 22 face opposite to the layer 24. During storage, release liner 28 will apply layer 26 until the medium is used.

The pressure sensitive adhesive useful for layer 26 may be any conventional pressure sensitive adhesive that adheres to both the surface and the film 22 of the item on which the inkjet recording medium is intended to place the correct permanent image. Pressure-sensitive adhesives are usually described in the reference (Satas Edit, Handbook of Pressure Sensitive Adhesives, 2nd Edition, Van Northland Reinhold 1989). Pressure sensitive adhesives are available from a variety of sources. Particularly preferred are acrylate pressure sensitive adhesives sold by the Minnesota Mining and Manufacturing Company, St. Paul, Minn., And disclosed in US Pat. Nos. 5,141,790, 4,605,592, 5,045,386, and 5,229,207.

Also, release liners are known for liner 28 and are commercially available from various sources. Non-limiting examples of release liners include silicone coated kraft paper, silicone coated polyethylene coated paper, polymeric materials coated or uncoated, such as polyethylene or polypropylene, as well as silicone urea, urethane and long chain alkyl acrylics. The aforementioned base materials coated with a polymer release agent such as late, such as those disclosed in US Pat. Nos. 3,957,724, 4,567,073, 4,313,988, 3,997,702, 4,614,667, 5,202,190 and 5,290,615 have.

Utility of the present invention

The ink jet recording medium of the present invention can be used in any environment where the ink jet image is desired to be accurate, stable, and fast in drying time. Commercially available graphics applications include opaque signs and banners.

The ink jet recording medium of the present invention has dimensional stability as measured by hygroscopic expansion having a size change of less than 1.5% in all directions at 10 to 90% relative humidity. Likewise, the media of the present invention are preferably used on coated paper because the paper is likely to change shape or size during processing or use.

The inkjet recording medium of the present invention can accommodate various inkjet ink formulations to form a fast drying time and accurate inkjet image. The thickness and composition of each layer of the inkjet recording medium are optimal depending on several factors such as the ink droplet volume, the ink liquid carrier composition, the ink type (dye, pigment or mixture), and the manufacturing technique (machine speed, resolution, roller structure). Can be changed for results. Inkjet ink formulations typically comprise a combination of colored dyes and / or pigments in water mixed with other solvents. Both water and other solvents transport the dyes and pigments to layer 14 or 24 and then continuously transport to membrane 12 or 22 for rapid drying of the image within layer 14 or 24 to form an accurate image. Done.

Drying can be measured by the time it takes for the image to become non-sticky or to bleed when lightly rubbed.

Formation of accurate inkjet images is provided by various commercial printing techniques. Non-limiting examples include thermal inkjet printers such as the trademark DeskJet, PrintJet, DeskWriter, DesignJet, and other printers available from Hewlett Packard Corporation, Palo Alco, CA. Also, there are piezo-type ink jet printers such as printers, spray jet printers, and continuous ink jet printers available from Seiko-Epson. Any of these commercially available printing techniques inject ink into the jet spray of a particular image in the media of the present invention. The present invention dries much faster than when the hygroscopic top coat (s) is applied to similar nonporous media.

3 and 4 illustrate a comparison of the media 10 of the present invention including membrane 12 and layer 14 and the inclusion of microporous membrane 12 alone. 3 is a cross-sectional micrograph of the microporous membrane 12 at about 5,000 times magnification. FIG. 4 is a cross-sectional micrograph at a magnification of the medium 10 having the membrane 12 including the major surface on which the hygroscopic layer 14 is present. As can be seen in FIG. 4, none of the hygroscopic layer 14 is present in the porous surface of the membrane 12.

The advantages of the structure of the medium 10 are readily apparent by comparison of FIGS. 5 and 6. FIG. 5 is an enlarged photograph of the film 12 of FIG. 3 having a distinct pattern at about 40 times magnification. The image is placed on the membrane with a printer of Trademark DeskWriter C using the brand name Hewlett Packard Inkjet Ink. FIG. 6 is an enlarged photograph of the medium of FIG. 4 having the same image having a distinct pattern. The image is placed on the membrane with a printer of Trademark DeskWriter C using the brand name Hewlett Packard Inkjet Ink. 6 shows the formation of the medium 10 in a more accurate image than produced by the combination of the film 12 and the layer 14.

5 and 6 show how the inkjet media of the present invention provide accurate images with excellent dot clarity.

As further shown in Figures 5 and 6, the media of the present invention have a good reflection color density which can be measured by the reflection optical density.

The media of the present invention may have the same pore volume and pore size as observed when forming such media using commercially available membranes. As shown in FIG. 4, the hygroscopic layer 14 may provide almost no modification to the effective pore volume or pore size of the membrane 12 (although some pores may be impregnated with the hygroscopic layer 14). It exists on the main plane of.

Uses of the image-formed media of the present invention include graphic appliques, for example, indoor decorations or outdoor billboards, trailer trucks, signboards, murals, and the like.

In the field of producing inkjet recording media, there has been no suitable combination of the best materials to provide accurate inkjet images suitable for applications that are rapidly drying and particularly require dimensional stability. The present invention recognizes a problem in providing a suitable layer for an ink jet recording medium to separate the solvent in the ink from the dye and pigment in the ink without causing excessive diffusion of the image.

The present invention seeks to solve the problems found in the art by providing a combination of layers in an inkjet recording medium that provides fast and accurate image drying.

As a first embodiment, the present invention seeks to provide an inkjet recording medium comprising a hydrophilic microporous polymer membrane having an opposite major side and a nonporous hygroscopic layer present on at least one major side of the membrane.

The combination of the two layers of the inkjet recording medium provides a feature in which neither layer has successfully solved the problem recognized in the art.

The hygroscopic layer provides a means for receiving inkjet images and retaining dyes and pigments contained in the ink.

The hydrophilic microporous polymer membrane provides a means for durablely supporting the hygroscopic layer comprising the inkjet image and a means for diffusing the solvent contained in the ink from the dyes and pigments retained in the hygroscopic layer.

The combination of the hygroscopic layer and the hydrophilic microporous polymer membrane provides a means for rapidly generating accurate inkjet images in durable media.

The term "hydrophilic" as used herein means that the contact angle of the liquid at the surface is less than 90 °.

As used herein, the term "hygroscopic" means that the layer can be hydrated by an aqueous mixture of the surfactant and solvent used in the inkjet ink, and the aqueous mixture is absorbed by the layer.

As used herein, the term "microporous polymer membrane" means a polymer film comprising interconnected void structures.

As used herein, the term "nonporous layer" means a layer that does not include interconnected pore structures.

As used herein, the term "hydrophilic microporous polymer membrane" means a polymer film that allows the surface tension and capillary action of an aqueous liquid, such as a mixture of solvent and surfactant, to absorb the liquid, ie, enter the pores of the membrane. do. The membrane preferably absorbs water at a pressure of less than 1 atmosphere.

The term "accurate" as used in the present invention means that the degree of dot spread caused by applying ink jet droplets to the sheet is less than that of the image inappropriately affecting the resolution. An example of an inaccurate image may be the appearance of image bleeding, uneven edges or mottled color.

As a second embodiment, the present invention provides the ink jet recording medium described above, and includes a pressure-sensitive adhesive layer applied to at least a portion of the second surface of the film.

As a third embodiment, the present invention provides an ink jet recording medium as described above, wherein the ink jet image is permanently disposed in a hygroscopic layer.

As a fourth embodiment, the present invention provides an inkjet recording medium comprising a hydrophilic microporous polymer membrane having opposite sides and a hygroscopic nonporous layer on at least one side of the membrane, the inkjet ink being in a predetermined image pattern. It provides a method for forming an accurate inkjet image that is rapidly dried, comprising the step of adding to the medium.

A first feature of the present invention is that the inkjet recording medium quickly provides an accurate inkjet image on the durable polymer support.

It is a second aspect of the present invention to provide an inkjet recording medium quickly providing an accurate and dense inkjet image without requiring special post-processing of the inkjet recording medium.

The first advantage of the present invention is that the inkjet recording medium is produced from a combination of two known layers and commercially available materials without complicated manufacturing and storage requirements.

A second advantage of the present invention is that the medium does not require the presence of particles such as starch, silica or clay in the layer of the medium, thereby making the image formation or handling excellent. However, such materials may provide additional handling benefits.

It is a third advantage of the present invention that the ink jet recording medium provides better reflection color density, better dot sharpness, dimensional stability and faster drying time than conventional ink jet recording media.

Embodiments of the present invention are described with reference to the accompanying drawings.

The following examples further illustrate embodiments of the present invention.

Test method

Drying time test

1) Form an image on the material using a suitable inkjet printer.

2) Measure the time it takes for the ink not to bleed when the finger is touched, the image is not damaged, or the adhesiveness of the image is not excessive.

Density measurement

All density measurements represent reflective optical densities and are measured with a density meter using a color filter that provides the maximum difference between the image and white.

Example

The characteristics of the ink jet recording medium on which the image is formed consist of the reflection optical density, the drying time, the resolution or the dot bleeding. Reflective optical density is measured using techniques known in the printing industry. In the Example of this invention, it evaluates using the Gretag SPM50 density meter which is commercially available from Gretag Limited in Rosendorf, Cheha-8105, Switzerland. Other instruments provide similar comparisons but not the same measurements. Drying time forms an image on the solid area and measures the length of time it takes for the image to blur or bleed when the image is slightly rubbed. Dot spread is determined by measuring a single dot line. The lower the value, the lower the dot spread. While zero dot spread provides the most accurate reproduction, some dot spread occurs as spherical droplets collide with the plane to hydrate the surface. Dot bleeding can be observed when the liquid diffuses into the coating in a coating that does not dry quickly.

Example 1

A coating solution of 25.0 g PVP-K90 polyvinyl pyrrolidone (ISP (International Specialty Products), 07470 Wayne Alps Road 1361, NJ) and 250.0 g deionized water was prepared.

These components were mixed until a clear solution was formed.

Experimentally measured Teslin microporous membrane pieces (Fiji Industry, 15272 Pittsburgh, Pa., Phi. It coat | covered and dried at 70 degreeC, and obtained the hygroscopic layer whose dry film weight is 4.2 g / m <2>. Images were formed using a trade name Hewlett Packard Deskwriter inkjet printer. The printer delivers about 140 picols of ink per drop. Scanning electron micrographs of the film cross section showed that the polymer was mainly present on the surface of the sheet.

Example 1b

For comparison, a piece of microporous membrane of the unmodified trade name Teslin was printed in the same manner, which was designated as Example 1b. Table 1 shows the density and drying time for this sample.

Example 2

The sample using the solution of Example 1 was coated as in Example 1 to obtain a dry coat weight of 6.6 g / m 2. Samples were imaged as in Example 1 to measure the effect of high film weight. Likewise, density data is presented in Table 1 below. Scanning electron micrographs of the coated cross sections showed that the polymer was mainly present on the sheet surface.

Example 3

The solution of Example 1 was coated on a microporous membrane disclosed in Example 5 of US Pat. No. 5,443,727 and having a thickness of 0.089 mm, Gurley porosity of 6 seconds / 50 cm 3 and pore volume of about 80%. The coating appeared to saturate through the membrane. Images were formed on the membrane as described above. A cross-sectional scanning electron microscope of the coating showed that the polymer was present on the sheet.

Example 3b

Images were formed on the film samples from Example 3 prior to coating for reference.

Example 4

Samples were printed for comparison, which is a commercially available material. The 3M color transparency material for the ink jet printer was imaged in the same pattern as in the above embodiment. The density attainable on this material is at its maximum since all materials are present on the surface and nothing is lost inside the medium. The drying time is excessively long because all liquid has to evaporate from the surface of the material.

Example Drying time (seconds) ROD black ROD Cyan ROD yellow ROD magenta Black line width ¹ Cyan Line Width One 15 1.74 1.47 1.02 0.95 0.41 / 0.41 0.35 / 0.33 1b 15 0.96 0.86 0.54 0.74 0.44 / 0.43 0.37 / 0.35 2 60 2.08 1.52 1.10 1.00 0.45 / 0.45 0.38 / 0.38 3 15 1.10 0.73 0.61 0.62 0.41 / 0.40 0.37 / 0.35 3b 15 0.73 0.66 0.46 0.48 0.51 / 0.50 0.41 / 0.40 4 > 300 1.85 1.27 0.77 0.70 0.45 / 0.45 0.41 / 0.40 ¹ horizontal / vertical mm width

Example 5

A coating solution of 50.0 g of trade name Polyox N-3000 polyethylene oxide [Union Carbide, Danbury Old Ridgebury Road 39, Connecticut, USA] and 950.0 g of deionized water was prepared.

These components were mixed until a clear solution was formed. A molded polypropylene film piece was coated and dried at 70 ° C. to obtain 4.2 g / m 2 of anhydrous film weight. The film was thermally laminated to the microporous membrane used in Example 3b with a heat roll laminator operating at 95 ° C. After cooling the composite, the polypropylene was stripped to leave a polyethylene oxide film on the microporous membrane. Examination revealed that the coating was present on top of the membrane. Images were formed on the coated film as described above. Although the imaging properties of the polymer were not as good as those of polyvinyl pyrrolidone, the composite material had a better image density than the uncovered material, so that the laminate covered the material and was hygroscopic on top of the microporous film where the film was fully saturated. We concluded that this is the method used to attach the top coat.

Example 5b

Example 5b prints the uncovered material for control.

Example 6

A 25.0 g tradename Polyox N-3000 polyethylene oxide (commercial carbide commercial), 25.0 g PVP-K90 polyvinyl pyrrolidone, 950.0 g deionized water, 1000.0 g isopropanol solution were prepared.

These components were mixed until a clear solution was formed.

This solution was coated onto a molded polypropylene film and dried in an oven operated at 77 ° C. (170 ° F.) to obtain an anhydrous film thickness of 50 μm, corresponding to a film weight of 5 g / m 2.

A heating with one steel roll and one unheated rubber roll, each heated at 96 ° C. (205 ° F.) for 3.8 seconds at a pressure of about 2.8 kg / cm 2 (40 lb / in ² ) on a brand name Teslin microporous membrane. Lamination was carried out in a roll laminator. Images were formed on this material as described above.

Example Drying time (seconds) ROD black ROD Cyan ROD yellow ROD magenta Black line width Cyan Line Width 5 120 0.97 1.33 0.86 0.90 0.48 / 0.42 0.43 / 0.38 5b 15 0.75 0.76 0.51 0.48 0.54 / na 0.44 / na 6 15 1.27 1.13 0.78 0.64 0.41 / 0.43 0.38 / 0.41 6b 15 0.89 0.83 0.48 0.58 0.53 / 0.47 0.43 / 0.46

In the examples below, the trade name Teslin microporous membrane was coated on one side with a pressure sensitive adhesive (75 μm thick) with a release liner (75 μm thick).

Test patterns were printed on the branded Hewlett Packard DesignJet 650C with HPS1640 cartridges available for the Hewlett-Packard DeskJet 1200C in 100% cyan, magenta, yellow, black (monochrome black), red, green and blue.

Reflection density was measured using Gretag SPM-50 (adjusted to 2 ', D65, ANSIT, Abs, No.).

Example 7

The following illustrates the rapid drying properties of the trade name Teslin, but also illustrates the disadvantages of low density imaging.

Uncoated tradename Teslin membrane pieces were charged to the equipped Trademark DesignJet 650C as described above and the test pattern was printed. Touching with a finger pad immediately after printing all the colors to detect any residual sticking or color off removal on the finger, the feel felt dry.

The density was measured. The density is shown in Table 3 below, all lower than the coated samples.

Example 8

A 10 wt% solution (weight / solution weight) of polyvinylpyrrolidone PVP K15, available from ISP (International Specialty Products, 07470 Wayne Alps Road 1361, NJ), was prepared in ethanol.

A sample of the brand name Teslin was coated with a notch bar (knife coater) using a gap adjusted to 3 mils with the above solution to produce an inkjet recording medium.

The PVP K15-coated Trademark Teslin flake was charged to the Trademark DesignJet 650C fitted as described above and the test pattern was printed. Touching with a finger pad immediately after printing all the colors to detect any residual sticking or color off removal on the finger, the feel felt dry. Visually, the image appears darker than the brand name Teslin membrane of Example 7.

Color density was measured. The densities are shown in Table 3 below and were all higher than uncovered samples.

Example 9

This example is intended to illustrate that the density obtained depends not only on the coating solution concentration but also on the coating formulation.

A 30 wt% solution (weight / solution weight) of polyvinylpyrrolidone PVP K15, commercially available from ISP (International Specialty Products, 07470 Wayne Alps Road 1361, NJ), was prepared in ethanol.

A sample of the brand name Teslin was coated with a notch bar (knife coater) using a gap adjusted to 3 mils with the above solution to produce an inkjet recording medium.

The resulting inkjet recording medium pieces were loaded into a brand name designjet 650C mounted as described above, and a test pattern was printed. Touching with a finger pad immediately after printing all the colors to detect any residual sticking or color off removal on the finger, the feel felt dry. Visually, the image appears darker than the trade name Teslin membrane of Example 7 and the inkjet recording medium of Example 8.

Example 10

This example is a solution of another type that can be used to coat the trade name Teslin (or other microporous film) to improve density in plain film images while maintaining good drying properties required for rapid handling and rapid drying after printing. To illustrate, use a printer having a wide format array or other rapid ink jet print means that will be born in the future.

The solution / dispersion was prepared as follows.

10 g of PVP K15 polyvinyl pyrrolidone available from ISP (International Specialty Products, 07470 Wayne Alps Road 1361, NJ) was prepared in ethanol. The solution was stirred vigorously and 10 g of Aerosil 380 silica (Degussa Corporation, Silica Division, 43017 Dublin Suite 450 Metro Place North 425, Ohio, USA) was added. The mixture was homogenized using a homogenizer equipped with a grinding screen (Silverson Machines, Inc., 01028 East Long Meadow Pio Box 589, Massachusetts, USA) at a rate of 1/3 for 5 minutes.

Samples of the brand name Teslin were coated with a notch bar (knife coater) using a gap adjusted to 3 mils with the mixture to create an inkjet recording medium.

The piece of media was loaded into the Trademark DesignJet 650C mounted as described above and the test pattern was printed. Touching with a finger pad immediately after printing all the colors to detect any residual sticking or color off removal on the finger, the feel felt dry. Visually, the image appears darker than any of the samples of Examples 7-9. Color density was measured. Density is shown in Table 3 below and all higher than the other samples.

Example 11

A 30% solution of PVP K15 described in Example 9 was coated on a plain 4 mil polyester (polyethylene terephthalate) film using a notched bar adjusted to a 3 mil gap.

PVP K15-coated polyester pieces were loaded into the Trademark DesignJet 650C fitted as described above and the test pattern was printed. All the colors were touched with a finger pad, and the touch felt wet right after printing. Color smeared easily by finger. The image was easily smeared, tacky after 10 minutes of printing, and tacky even after 20 minutes of printing.

All of the coatings described in the examples were dried at 110 ° C. (230 ° F.) for 3 minutes.

material ROD Cyan ROD magenta ROD yellow ROD black Drying time Example 7 (plain teslin) 0.89 0.667 0.5 0.703 Immediately Example 8 (Teslin + 10% PVP K15) 0.896 0.705 0.612 0.646 Immediately Example 9 (Teslin + 30% PVP K15) 0.79 0.613 0.66 0.62 Immediately Example 10 (Teslin + PVP K15 / Aerosil 380) 1.484 1.194 0.913 1.005 Immediately Example 11 (PET substrate) > 20 minutes

The present invention is not limited by the above embodiments. Claims are as follows.

Claims (14)

An inkjet recording medium comprising a hydrophilic microporous polymer membrane having opposing major faces and a hygroscopic layer present on at least one membrane surface. The inkjet recording medium of claim 1, wherein the film is a polymer film that absorbs an aqueous liquid. The inkjet recording medium of claim 1, wherein the film absorbs water at a pressure of less than 1 atmosphere. The inkjet recording medium according to claim 1, wherein the main surface of the film opposite to the hydrophilic layer is sealed by a film or by another manufacturing process. An inkjet recording medium according to claim 1, wherein the void structure of claim 1 is decomposed to provide transparency by post-processing after image formation such as heating or calendering. An ink jet recording medium according to claim 1, wherein the hygroscopic layer is a water-soluble or water-swellable coating. The inkjet recording medium of claim 1, wherein the film has a micro-voided structure, and is selected from the group consisting of polyolefins, polyesters, halogenated polyvinyls, and acrylics. The inkjet recording medium of claim 1, wherein the hygroscopic layer comprises a mordant, an ultraviolet light absorbent, an antioxidant, a filler, a surface wear aid, a blocking aid, or other materials to improve image stability and handleability. The inkjet recording medium according to claim 1, wherein the main surface of the film opposite to the hygroscopic layer is coated with an adhesive and subsequently bonded to another surface. An inkjet image comprising an inkjet recording medium comprising a hydrophilic, microporous polymer membrane having opposite major surfaces, a hygroscopic layer present on at least one surface of the membrane and an inkjet image in permanent contact with the hygroscopic layer. The inkjet image of claim 10, wherein the image is an overhead transparency image. The inkjet image of claim 10, wherein the image is a graphic applique. The inkjet image of claim 10 wherein the major surface of the film opposite the hygroscopic layer is coated with an adhesive and subsequently bonded to another layer. (a) providing an inkjet recording medium comprising a hygroscopic microporous polymer membrane having opposing major faces and a hydrophilic layer present on at least one membrane surface; And (b) injecting inkjet ink into contact with the inkjet recording medium in a predetermined image pattern, thereby forming an accurate permanent inkjet image.