WO2001092004A1

WO2001092004A1 - Waterfast backprint ink jet receiver medium

Info

Publication number: WO2001092004A1
Application number: PCT/US2001/015903
Authority: WO
Inventors: Brian L. Anderson; Brenda M. Warren; David Hews
Original assignee: Rexam Graphics
Priority date: 2000-05-31
Filing date: 2001-05-17
Publication date: 2001-12-06
Also published as: AU2001263214A1

Abstract

Provided is an ink jet receiving medium comprising a transparent substrate and a dual layer ink receiving system thereon. The top layer, which first contacts the ink, comprises a mixture of non-porous and porous silica, as well as a blend of a vinylacetate copolymer and a fully hydrolyzed polyvinyl alcohol. The second layer, or lower layer, comprises a water soluble polymer and a quaternized ammonium resin. The resulting ink jet receiving sheet permits the ink to quickly pass through the top layer and be absorbed in the lower or second layer, and become locked, thereby creating a waterfast ink jet print.

Description

ATERFAST BACKPRINT INK JET RECEIVER MEDIUM

RAC OROTT Ό OF THF, INVENTION Field of the Invention

The present invention relates to an ink jet receiving medium for viewing of an image through a transparent substrate . In particular, the present invention relates to such an ink jet receiving medium which yields a waterfast ink jet print and a process for providing such a waterfast ink jet print, thereby allowing the medium to be successfully used both indoors and outdoors .

Description of Related Art Printers using sprayable inks, such as ink jet printers, have become popular due to a number of desirable features. Specifically, these systems operate quietly at high speed ^* , without the need for external developing or fixation procedures. Moreover, through the use of multiple ink jet heads, various colors may be obtained which are suitable for a variety of applications. These printers typically employ ink jet heads having small orifices that propel ink droplets and are used in various electronic printing applications. Various methods for ejecting droplets of ink have been developed. These methods include the use of an electrostatic attraction system, the use of a piezoelectric element to impart mechanical vibration or displacement to the ink, and pressurizing the ink by heating. Thus, it is no wonder that such a recording method which generates less noise and is capable of performing high-speed printing and multi-color printing is in great demand. Ink jet systems are typically comprised of three components: the printer, the ink and the receptor. The printer controls the size, number and placement of the ink droplets and contains the transport system. The ink provides the colorants which form the image, and the receptor provides the medium which accepts and holds the ink. The quality and stability of the resultant ink jet print is a function of the system as a whole. However, the composition and interaction of the ink and the receptor material most affect the quality and stability of the imaged product .

More specifically, it is desired that the ink be absorbed as rapidly as possible, and that the spread of ink droplets be adequate. The resultant image should be excellent in storability, durability and water resistance or waterfastness . Ink compositions which are useful in ink jet recording systems are well known and generally contain water, organic solvents and dyes.

Typically, ink jet systems fall broadly into two categories; those that employ high organic solvent-water based inks, and those that are essentially aqueous. The resultant ink jet print using either of these types of ink has generally been found to exhibit a waterfastness for which improvement is desired (i.e., the dye image leaches out or the image layer containing the dye dissolves when contacted with water) . Additionally, the dye image is prone to smudging.

Ink jet film compositions are normally sensitive to water and the print can dissolve and leach out. Also, under humid conditions, the print can bleed thereby losing definition. This deterioration is generally accentuated when the inks employ high boiling solvents, such as glycols.

Polymeric films for use as recording media represent a special problem in ink jet recording because their surfaces are hydrophobic or quasi-hydrophobic . Even when their surfaces are treated with special coatings to accept and absorb the inks, it is difficult to obtain the requisite qualities of image density and resolution without incurring tack, smear, image bleed, water solubilization of the ink receptive matrix, or other undesirable properties . The use of water/glycol ink systems presents a special problem. At high humidities, a phenomenon described as image bleed, occurs. The ink jet printer applies small ink droplets in a selective pattern to form the images. These droplets are absorbed into the coating on the film surface to form dots.

After initial absorption, the dye continues to spread laterally. Some post imaging spread is desirable to fill in the white areas between the dots and obtain good image density. At high humidities, however, this spreading continues and causes the image to spread excessively, that is, to bleed thereby losing image sharpness or resolution.

Various attempts have been made to solve these problems in an effort to provide the optimal receptor. Approaches to the problem of hydrophobic surfaces include the use of polymers alone or in admixture as ink receptive coatings; see for example, U.S. Patent Nos . 4,503,111; 3,889,270; 4,564,560; 4,555,437 and 4,578,285. Multiple coatings have also been employed in trying to overcome the various problems associated with the hydrophobic nature of recording media; illustrative of these coatings are those described in U.S. Patent No. 4,379,804, Japanese Patent Number 01041589 and Japanese Disclosure Numbers 86-132377; 86-074879 and 86-41549. Additionally, the use of mordants to help fix the dye and minimize bleed has been the subject of a number of patents, including U.S. Patent Nos. 4,554,181; 4,578,295 and 4,547,405. A waterfast ink jet medium is described in U.S. Patent No. 5,853,899, where the ink receptive coating is comprised of a blend of an ethylene vinylacetate copolymer and a fully hydrolyzed polyvinyl alcohol . Improvements or alternatives, however,^' are always welcome. Moreover, there is a strong demand for a recording medium having light transmissivity and a recording medium having gloss on the surface. In these cases it is essential that the surface of the recording medium be non-porous. In this regard, in order to enhance ink affinity and ink receptivity, it has been the practice in the prior art to use a recording medium comprising a non-porous, ink-receiving layer formed by use of a water-soluble polymer.

For example, U.S. Patent No. 4,503,111 assigned to Tektronics discloses a recording medium having a non-porous ink- receiving layer formed by using primarily a polyvinylpyrrolidone . However, such a recording medium has various problems. These problems include a recorded image low in light fastness, or that due to the stickiness of the surface of the inked receiving layer, blocking is liable to occur, when the printed media are placed upon one another, or when paper is superposed on the recorded surface .

U.S. Patent No. 5,206,071 to Atherton et al . relates to film mediums useful in ink jet printing which films comprise a transparent, translucent or opaque substrate, having on at least one side thereof a water-insoluble, water-absorptive and ink- receptive matrix comprised of a hydrogel complex and a polymeric high molecular weight quaternary ammonium salt .

U.S. Patent No. 4,877,680 to Sakaki et al . relates to a recording medium comprising a substrate and a non-porous ink receiving layer. The ink receiving layer contains a water- insoluble polymer containing a cationic resin. The recording medium may be employed for recording by attaching droplets of a recording liquid thereon. U.S. Patent No. 4,576,867 to Miyamoto relates to an ink jet recording paper wherein by attaching a cationic resin to at least the surface of an ink jet recording paper, the water- resistance and the sunlight fastness of the image formed on the ink jet recording paper can be improved. European patent publication 0,500,021 Al relates to a recording method and recording film comprising a transparent substrate, a porous alumina hydrate layer formed on the substrate and an opaque porous layer laminated on the alumina hydrate layer. Backprint media have transparent substrates, but have always had a problem with waterfastness; limiting . their outdoor use. There is a definite need for a waterfast backprint medium, particularly for use with light boxes where the light shines through the image layer and the image is viewed through the substrate. Besides being waterfast, the medium must also provide a printed image which is vivid and bright, particularly if the medium is to be used outdoors.

Accordingly, an object of the present invention is to provide a novel backprint recording medium for ink jet recording which is particularly excellent in ink receptivity, sharpness and most importantly waterfastness .

Another object of the present invention is to provide such a backprint recording medium for ink jet recording which is excellent in waterfastness, even under highly humid conditions, so that the medium can be used indoors or outdoors .

Still another object of the present invention is to provide a waterfast backprint ink jet print and a method for preparing some. These and other objects of the present invention will become apparent upon a review of the specification and the claims appended thereto.

SUMMARY OF THE INVENTION According to one aspect of the present invention, there is provided an ink jet receiving medium comprising a substrate and a dual layer ink receiving system thereon. The top layer, which first contacts the ink, comprises a mixture of non-porous and porous silica, as well as a blend of a vinylacetate copolymer and a fully hydrolyzed polyvinyl alcohol. The second layer, or precoat or lower layer, comprises a water soluble polymer and a quatemized ammonium resin. Preferably, the water soluble polymer is in mixture with a hydrophobic polymer, which is generally present as an aqueous emulsion. It is also preferred that the hydrophobic polymer is carboxylated. The presence of the quatemized ammonium resin in the second layer is important as it greatly improves the waterfastness of the system.

The resulting ink jet receiving sheet permits the ink to quickly pass through the top layer and be absorbed in the lower or second layer, and become locked, thereby creating a waterfast ink jet print. When used with a transparent substrate, i.e., a clear film substrate, the resulting image is readily viewed through the substrate. The image print intensity is vibrant when light is shone through the image layer and the image is viewed through the substrate. The print intensity remains bright and vibrant even when no light is used.

BRIEF DESCRIPTION OF THE DRAWING The Figure of the Drawing depicts the product construction of Example 1.

DETATT.ED DESCRIP IO OF THE PREFERRED EMBODIMENTS The present invention involves an ink jet receiving medium comprised of a dual layer ink receiving system. The use of the dual layers of the present invention has been found to allow quick dry times, avoid any bleeding, and most importantly, create an extremely waterfast ink jet print. For it has been found that the nature of the top layer or first layer which contacts the ink first, allows the ink to quickly pass through the bottom layer, where the ink becomes locked.

The top layer comprises a mixture of non-porous and porous silica, which silica is well known in the art. By non-porous silica is intended low pore volume silica, which is silica having a pore volume of 0.8 cc/gm or less, more preferably a pore volume of 0.5 cc/gm or less, and most preferably a pore volume of 0.4 cc/gm or less. The porous silica is a high pore volume silica, which is silica having a pore volume of at least 1.5 cc/gm, more preferably a pore volume of at least 1.6 cc/gm, and most preferably about 1.6 cc/gm or in the range of from 1.6 to 2.0 cc/gm. The differentiation in pore volume between the porous and non-porous silica should be at least about 1.0 cc/gm. In a preferred embodiment, the non-porous silica has a pore volume of about 0.4 cc/gm, and the porous silica has a pore volume of about 1.6 gm/cc.

The top layer further comprises a blend of vinylacetate copolymer and a fully hydrolyzed polyvinyl alcohol . These resins render the top or first layer extremely waterfast. The second or bottom layer comprises a water soluble polymer, preferably a polyvinylpyrrolidone, and a quate ized ammonium resin. The water soluble polymer can also be in mixture with a hydrophobic polymer, which is preferably carboxylated. Conventional additives such as surfactants or anti-blocking agents can be present in either or both of the layers of the system. The two layers can be coated using conventional techniques .

The substrate onto which the dual layer ink receptive system is coated is preferably a clear film. Any suitable transparent, clear film can be used as the substrate. Conventional clear films are known, for example, polyester, clear vinyls and clear polycarbonate films are all available commercially. In a preferred embodiment, a polyester substrate (such as the polyester film MELINEX 535 available from DuPont) or a clear polycarbonate film is used as the substrate.

The dual layer system of the present invention, when coupled with the transparent substrate, provides one with a waterfast backprint film for ink jet printing. The ink passes through the top layer, and becomes locked into the second or bottom layer. The dry time is short, and the image is resistant to outside water. The image as viewed through the substrate is bright and vibrant, with or without artificial light shining through from the image layer. The result is a backprint ink jet medium which can provide a printed image useful for light boxes, and for both indoor and outdoor use .

The invention will be illustrated in greater detail by the following examples. It is understood that these examples are given by way of illustration and are not meant to limit the disclosure or the claims that follow. All percentages in the examples, or elsewhere in the specification, are by weight unless otherwise specified.

Example 1

Precoat : (100 part formula)

Deionized Water 69.07 Tinopal SFP 0.01

PVP K90 7.60

Lucidene 243 23.27

Zonyl FSN 0.05

The above mix was prepared by dissolving the PVP K90 in water with a Lightn'in mixer on moderate to high speed for 30 minutes. The Lucidene 243 and Zonyl FSN were then added and mixed for an additional 10 minutes.

The precoat was coated onto Melinex 535 clear polyester film with a 42 Mayer rod and dried in a Blue M convection oven at 220F for 2 minutes to give a dry coating weight of about 2.0 lbs.

Topcoat: (100 part formula)

Deionized Water 65.20

Tinopal SFP 0.04

Syloid AL-1 3.44

Syloid W-300 11.47 Airvol 325 10% 7.90

Airflex 110 5.80

Gafquat 755N 5.45 Agefloc A50HV 0.60 Zonyl FSN 0.10

The above mix was prepared by dispersing the Tinopal SFP, Syloid AL-1, and Syloid W-300 into the water on a Silverson mixer at high speed for 10 minutes. Add the remaining ingredients, mixing for 5 minutes in between each one at moderate speed.

The topcoat was then coated onto the precoated sample with a 44 Mayer Rod and dried in a Blue M convection oven to achieve a dry coating weight of 3.25 lbs/MSF. See the Figure of the Drawing for a product construction diagram. Note also that any images would be viewed through the clear substrate, and that artificial light can be shone through the image layer if desired.

The sample was then printed on an Encad Novajet Pro with the GS ink set using a full color test pattern. Reflective image densities were taken on cyan, magenta, yellow, black, red, green and blue using an XRITE 938 densitometer . Transmitted densities were taken using a MacBeth . The samples were then sprayed with water while hanging vertically and rated subjectively for water astness . The results can be seen in the Table below.

Comparative Example 1

Deionized Water 48.59 parts by weight

Syloid W-300 16.98

Syloid 620 2.77 Tinopal SFP 0.04

Airvol 325 10% soln. 16.30

Airflex 110 11.49

Gafquat 755N 1.00

Agefloc A50HV 2.72 Zonyl FSN 0.11

The above mix was prepared by dispersing the Tinopal SFP, Syloid W-300, and Syloid 620 into the water on a Silverson mixer at high speed for 10 minutes. Add the remaining ingredients, mixing for 5 minutes in between each one at moderate speed.

The mix was then coated onto Melinex 535 clear polyester film with a gapped 110 Mayer rod and dried at 220F for 6 minutes to achieve a dry coating weight of about 6.5 lbs/MSF. The sample was then printed and evaluated in the same manner as Example 1. The results can be seen in the Table below.

Comparative Example 2

Deionized Water 41, .20 parts by weight

Ethanol 20, .00

Tinopal SFP 0, .02

PVP K90 3. .58

Tiosorb I 2, .07

12.5% Gohsenal T- 28, .67

330H

Silcron G-100 4, .29

Zonyl FSJ 0, .17

The above mix was prepared by dissolved the Tinopal SFP and

PVP K90 into the water and ethanol blend on a waring blender for four minutes. The remaining four ingredients were added to the Waring and mixed for an additional four minutes. The mix was then coated as in Example 1 and dried. The sample was then printed and evaluated in the same manner as Example 1. The results are reported in the Table below.

lABL-E

The foregoing results demonstrate the superior combination of waterfastness and image intensity achieved by using the dual layer system of the present invention. Use of the dual layer system permits one to prepare a waterfast backprint ink jet medium, which can be used in light boxes indoors and/or outdoors, and which yields intense and vibrant images whether the light is or is not on.

In the foregoing examples, the following components were used:

Syloid W-300 -- Hydrated amorphous silica from W.R. Grace, Baltimore, Md.

Airflex 110 -- Vinyl acetate/ethylene copolymer latex from Air products and Chemicals, Inc. of Allentown, Pa.

Airvol 325 -- Fully hydrolyzed polyvinyl alcohol from Air products and Chemicals, Inc. of Allentown, Pa.

Silcron G-100 -- amorphous silica from SCM chemicals of Baltimore, Md. PVP K90 — polyvinyl pyrrolidone molecular weight ~ 1,000,000 from International Specialty Polymers of Wayne, NJ.

Syloid AL-1 -- amorphous silica from W.R. Grace, Baltimore, Md.

Syloid 620 -- amorphous silica from W.R. Grace, Baltimore, Md.

Agefloc A-50HV — poly (Hydroxyalkene Ammonium Chloride) from C.P.S. Chemicals of Old Bridge, NJ.

Zonyl FSN — Nonionic fluorosurfactant from DuPont of Wilmington, De.

Gafquat 755N - Quatemized copolymer of vinyl- pyrrolidone and dimethylaminoethyl methacrylate from International Specialty Products of Wayne, NJ

Tinopal SFP -

Lucidene 243 - Styrenated acrylic emulsion from Morton International of Chicago, IL.

While the invention has been described with preferred embodiments, it is to be understood that variations and modifications may be resorted to as will be apparent to those skilled in the art upon reviewing the specification. Therefore, it is to be understood that the invention disclosed is intended to cover such modifications that fall within the scope of the appended claims.

Claims

WHAT TS CLAIMED IS:

1. An ink jet receiving medium comprised of a transparent substrate and a dual layer ink receiving system coated thereon, with the top layer of the ink receiving system comprising a mixture of porous and non-porous silica, and a blend of a vinylacetate copolymer and a fully hydrolyzed polyvinyl alcohol, and with the bottom layer of the system comprising a water soluble polymer and a quate ized ammonium resin.

2. The ink jet receiving medium of claim 1, wherein the water soluble polymer of the bottom layer comprises polyvinylpyrrolidone .

3. The ink jet receiving medium of claim 1, wherein the bottom layer further comprises a hydrophobic polymer.

4. The ink jet receiving medium of claim 3, wherein the hydrophobic polymer is carboxylated.

5. The ink jet receiving medium of claim 1, wherein the substrate is a polyester, clear vinyl or polycarbonate film.

6. The ink jet receiving medium of claim 5, wherein the substrate is a polyester or polycarbonate film.

7. The ink jet receiving medium of claim 1, wherein the porous silica has a pore volume of at least 1.6 cc/gm.

8. The ink jet receiving medium of claim 7, wherein the porous silica has a pore volume of from 1.6 to 2.0 cc/gm.

9. The ink jet receiving medium of claim 1, wherein the non-porous silica has a pore volume of 0.5 cc/gm or less.

10. The ink jet receiving medium of claim 9, wherein the non-porous silica has a pore volume of about 0.4 cc/gm.

11. The ink jet receiving medium of claim 1, wherein the differentiation in pore volume between the porous and non-porous silica is at least 1.0 cc/gm.

12. A method for preparing a waterfast ink jet medium which comprises the steps of a) providing a substrate; b) coating the substrate with a layer comprised of a water soluble polymer and a quatemized ammonium resin; and c) coating a top layer over the bottom layer comprised of a mixture of porous and non-porous silica, and a blend of a vinylacetate copolymer and a fully hydrolyzed polyvinyl alcohol.

13. The method of claim 12, wherein the substrate is a transparent polyester film.

14. The method of claim 12, wherein the substrate is a transparent polycarbonate film.

15. The method of claim 12, wherein the layer of b) further comprises a hydrophobic polymer.

16. The method of claim 15, wherein the hydrophobic polymer is carboxylated.

17. The method of claim 12, wherein the porous silica has a pore volume of from 1.6 to 2.0 cc/gm and the non-porous silica has a pore volume of 0.5 cc/gm or less.

18. The method of claim 12, wherein the differentiation in pore volume between the porous and non-porous silica is at least 1.0 cc/gm.

19. An ink jet print created by printing an image with an ink jet printer on an ink jet receiving medium comprised of a transparent substrate and a dual layer ink receiving system coated thereon, with the top layer of the ink receiving system comprising a mixture of porous and non-porous silica, and a blend of a vinylacetate copolymer and a fully hydrolyzed polyvinyl alcohol, and with the bottom layer of the system comprising a water soluble polymer and a quatemized ammonium resin.

20. The ink jet print of claim 19, wherein the water soluble polymer in the bottom layer of the ink jet medium is polyvinylpyrrolidone .