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United States Patent [i9]
Glocker et al.
US005558843A Patent Number: Date of Patent:
5,558,843 Sep. 24, 1996
 NEAR ATMOSPHERIC PRESSURE TREATMENT OF POLYMERS USING HELIUM DISCHARGES
 Inventors: David A. Glocker, West Henrietta;
Mark M. Romach, Rochester, both of
 Assignee: Eastman Kodak Company, Rochester, N.Y.
 Appl. No.: 299,776
 Filed: Sep. 1, 1994
 Int. CI.6 B01J 19/08
 U.S. CI 422/186.05; 422/907
 Field of Search 422/186.05, 907
 References Cited
U.S. PATENT DOCUMENTS
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"Proc. Jpn. Symp. Plasma Chem. 2", 1989, pp. 109-112, by A. Nagata, S. Takehiro, H. Sumi, M. Kogama, S. Okazaki, and Y. Horikie.
J. Phys. D: Appl. Phys 23 (1990) pp. 1125-1128, "The Mechanism of the Stabilization of Glow Plasma at Atmospheric Pressure" by T. Yokoyama, M. Kogoma, T. Moriwaki, and S. Okazaki.
"Rapid Communication: Appearance of Stable Glow Discharge in Air, Argon, Oxygen, and Nitrogen at Atmospheric Pressure Using a 50Hz Source", pp. 889-892 by S. Okazaki, M. Kogoma, M. Uehara, and Y. Kimura.
(List continued on next page.)
Primary Examiner—Harvey E. Behrend
Assistant Examiner—Daniel Jenkins
Attorney, Agent, or Firm—Arthur H. Rosenstein
The present invention is a method and apparatus for treating a polyester support such as polyethylene napthalate or polyethylene terephthalate. The treatment is carried out at near atmospheric pressure in a gas of helium and nitrogen or oxygen. The treatment uses anodized aluminum electrodes and an atmospheric glow discharge results when the electrodes are connected to an RF generator and spaced about 2 mm apart. The process and apparatus improve adhesion of subsequently coated emulsions on the polyester support.
2 Claims, 1 Drawing Sheet
J. Phys. D: Appln. Phys. 23 (1990) pp. 374-377, "The Improvement of the Atmospheric Pressure Glow Plasma Method and the Deposition of Organic Films", by T. Yokoyama, M. Kogoma, S. Kanazawa, T. Moriwaki, and S. Okazaki.
Nuclear Instruments and Methods in Physics Research B37/ 38 (1989) pp. 842-845, "Glow Plasma Treatment at Atomspheric Pressure for Surface Modification and Film Deposition" by S. Kanazawa, M. Kogoma, S. Okazaki, and T. Moriwaki.
J. Phys. D: Appln. Phys. 21 (1988) pp. 838-840, "Stable Glow Plasma at Atmospheric Pressure" by S. Kanazawa, M. Kogoma, T. Moriwaki, and S. Okazaki.
NEAR ATMOSPHERIC PRESSURE
TREATMENT OF POLYMERS USING
FIELD OF THE INVENTION 5
The present invention is a novel process for treating photographic support with electrical discharges at atmospheric pressure to promote adhesion of subsequent coated layers. 10
BACKGROUND OF THE INVENTION
Corona discharges are used widely to promote adhesion between various materials. In manufacturing photographic products there is a large body of literature describing various applications of coronas to make aqueous and non-aqueous coatings adhere to various substrate materials. Almost all of these coronas are produced by applying a high voltage (approximately 5-10 kV), relatively high frequency (10 2Q kHz) signal to electrodes in an ambient atmosphere at atmospheric pressure. See for example, U.S. Pat. Nos. 4,241,169; 4,701,403; 4,087,575; 4,429,032; 4,363,872; 4,229,523; 4,394,442; 3,411,908; 3,531,314; 3,582,339; 3,607,345; 3,630,742; 3,860,427; 3,874,877; 3,888,753; 4,055,685; 4,518,681; 5,004,669; French Patent 7613034 and European Patent Application No. 92303556.2. However, there are limitations to the usefulness of corona treatments. Corona treatments produce locally energetic discharges, commonly known as streamers, and these streamers may 3Q cause a non-uniform level of treatment. They may also be related to an inhomogeneous loss of red speed in photographic emulsions which produces a mottle defect. Furthermore, corona treatments appear to be effective at promoting adhesions of various coatings to polyethylene but are rela- 35 tively ineffective at promoting the adhesion of layers to various polyester supports such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN).
A more controllable and effective way of preparing polymers for coating is with a low pressure glow discharge 40 treatment. Glow discharges are, by nature, very diffuse and homogeneous, producing a more uniform treatment. Moreover, by controlling the gas it is possible to improve the adhesion of photographic layers to materials such as polyesters as well as polyethylene. See for example, U.S. Pat. 45 Nos. 4,993,267; 3,837,886 and 4,451,497. A major disadvantage in glow discharge treatments done at reduced pressures is the problem of maintaining a low pressure at the treatment station. It is necessary to use either a batch process, in which the support is loaded into a treatment 50 chamber and the air is removed, or an in-line process which requires that the support pass through a differential pressure region. In the first case, the support must go through an additional off-line step before coatings are applied. This is unattractive from a product flow perspective and requires 55 additional capital. The second choice is difficult and expensive to implement because of the very tight tolerances needed to maintain the pressure differentials in the transport path. This requires expensive and complicated hardware and pumps. The closer to atmospheric pressure that the treat- go ments can be done, the simpler and less costly the process becomes.
It is known that under certain conditions, stable diffuse glow discharges can be produced at atmospheric pressures. Articles that discuss stable glow discharges are as follows: 65 S. Kanazwa, M. Kogoma, T. Moriwaki and S. Okazaki, J. Phys. D: Appl. Phys 21 (1988), pp. 838-840; S. Kanazwa,
M. Kogoma, S. Okazaki and T. Moriwaki, Nuclear Instruments and Methods in Physics Research, B37/38 (1989) pp. 842-845; T. Yokoyama, M. Kogoma, S. Kanazawa, T. Moriwaki and S. Okazaki, J. Phys. D: Appl. Phys. 23 (1990) pp. 374-377; T. Yokoyama, M. Kogoma, T. Moriwaki and So. Okazaki, J. Phys. D: Appl. Phys. 23 (1990) pp. 1125-1128 and A. Nagata, S. Takehiro, H. Sumi, M. Kogoma, S. Okazaki, and Y. Horikie, Proc. Jpn. Symp. Plasma Chem 2 (1989) pp. 109-112. Work in this area has been limited and directed primarily at etching of photoresist and deposition of materials. These articles indicate that a reliable method of producing diffuse glow discharges at atmospheric pressure is to use helium as the discharge gas. The work reported in the literature has been reproduced and found to be reliable. It has also been found that very small amounts of reactive gases, such as a few percent nitrogen or oxygen, will extinguish an atmospheric helium discharge. However, we have also found that by using trace amounts of reactive gases, stable discharges can be produced at very close to atmospheric pressure which are also able to dramatically improve the adhesion of photographic emulsions to difficult to coat materials such as polyethylene, PET and PEN.
The present invention allows one to treat polymeric surfaces with a stable atmospheric glow discharge so that adhesion of photographic emulsions is improved between the photographic emulsions and the polymeric materials.
SUMMARY OF THE INVENTION
The present invention is a method of treating a polymeric support. The method includes providing a first electrode having a first surface, the first electrode having a plurality of spaced apart holes adjoining the first surface, the first surface being insulated. A second electrode having a second surface is positioned in a spaced apart relationship from the first surface of the first electrode. Gas is pumped through the plurality of holes at a pressure greater than or equal to atmospheric pressure. The gas comprises helium, oxygen and nitrogen. A power supply is coupled to the first electrode, the power supply has a frequency of between 10 kH to about 50 MHz. A web is positioned between the first surface of the first electrode and the second surface of the second electrode wherein the polymeric web is subjected to atmospheric glow discharge to improve the adhesive properties.
The present invention also includes a device adapted for use in an atmospheric glow discharge chamber which includes an electrode having a first surface, the first surface including a plurality of holes terminating at the first surface, the first surface of the electrode being insulated. A gas is provided to the plurality of holes and a power supply is coupled to the electrode.
The present invention provides the advantage of improving the adhesive properties of a polyester substrate using glow discharge device that operates at atmospheric pressures.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic of a prior art device used to obtain an atmospheric glow discharge.
FIG. 2 shows an electrode configuration of the present invention for the continuous treatment of a moving web.
For a better understanding of the present invention together with objects, advantages and capabilities thereof,