US3346480A - Apparatus for corona treatment of polymer film including a flexible metal foil electrode - Google Patents

Apparatus for corona treatment of polymer film including a flexible metal foil electrode Download PDF

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US3346480A
US3346480A US392147A US39214764A US3346480A US 3346480 A US3346480 A US 3346480A US 392147 A US392147 A US 392147A US 39214764 A US39214764 A US 39214764A US 3346480 A US3346480 A US 3346480A
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electrode
electrodes
film
corona
metal foil
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US392147A
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Henry G Schirmer
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WR Grace and Co
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WR Grace and Co
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Priority to US392147A priority Critical patent/US3346480A/en
Priority to GB33858/65A priority patent/GB1112196A/en
Priority to DE19651504332 priority patent/DE1504332A1/en
Priority to FR29483A priority patent/FR1445321A/en
Priority to US688629A priority patent/US3405052A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B26—HAND CUTTING TOOLS; CUTTING; SEVERING
    • B26F—PERFORATING; PUNCHING; CUTTING-OUT; STAMPING-OUT; SEVERING BY MEANS OTHER THAN CUTTING
    • B26F1/00—Perforating; Punching; Cutting-out; Stamping-out; Apparatus therefor
    • B26F1/26—Perforating by non-mechanical means, e.g. by fluid jet
    • B26F1/28—Perforating by non-mechanical means, e.g. by fluid jet by electrical discharges

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  • the film is passed between a pair of electrodes having an extended surface area to which is ap plied a high value alternating potential sufficient to produce a diffuse corona between the electrodes.
  • the corona is apparently caused by partial breakdown or ionization of the atmosphere around an electrode.
  • the electrodes must be so spaced that the film surface is exposed to the corona.
  • the electrodes may comprise a pair of fiat plates positioned parallel to one another.
  • the electrodes may also comprise a drum having a stator spaced apart and concentric therewith.
  • dielectric covering may also prevent an arc-over and damage to the film being treated in the event that said film has pin holes or other weak spots therein.
  • the dielectric covering also prevents pitting of the electrode and helps to spread the corona over the entire width of the electrode and causes the film to be a minor portion of the total dielectric in the gap.
  • Suitable dielectrics for ground roll coverings are glass, Mylar, epoxy resins and elastomers, such as chlorosulfonated polyethylene, silicone rubber and the like, and anodized coatings. The elastomers are generally preferred since the only maintenance required is that it be kept free of any surface irregularities to prevent treat-through.
  • Still another object of the invention is to provide apparatus for the formation of a corona.
  • a thin, flexible, electrically conductive, area electrode for example, aluminum foil
  • a discharging electrode in conjunction with a discharging electrode will produce a uniform electrical discharge and corona if a high-value alternating potential is applied across said electrodes. Further, if the flexible electrode is minimumly supported so that the remainder of the electrode is unsupported, said electrode will adjust itself to a coronaproducing distance from the discharging electrode.
  • the charging electrode may comprise an arcuate plate electrode composed of a sintered metal.
  • FIGURE 1 is a perspective view of a suitable embodiment employing an aluminum foil electrode for the corona treatment of thermoplastic film such as polyethylene or polypropylene.
  • FIGURE 2 is a cross section of a sintered arcuate 3,345,48fi Patented Oct. 10, 1967 plate electrode employed in lieu of the aluminum foil electrode shown in FIGURE 1.
  • a grounded steel cylindrical electrode 4 mounted on a shaft 6 driven by any suitable driving means such as motor 8.
  • the opposite end may be mounted onto the framework by any suitable means such as a journal box 10.
  • the exterior surface of the grounded electrode 4 is preferably, but not necessarily, covered with an insulating substance 12, such as rubber.
  • the grounded electrode is shown as rotating in the clockwise position looking from the motor end of the shaft.
  • the film 14 enters the frame 2 through a slot 3, passes under guide roller 5, over electrode 4 and under guide roller 7.
  • a thin, flexible, electrically conductive smooth sheet-like material such as aluminum foil, which may be attached to any suitably supporting means 9 or to a blade electrode (not shown).
  • the aluminum foil may be attached at any suitable location on the foil such as at the middle portion or at any edge, for example, the posterior edge relative to the movement of the film. However, the foil can be supported at only one point or in any plane transverse the moving web.
  • the aluminum foil Upon the application of a potential across the electrodes, the aluminum foil is attracted to the grounded electrode but does not contact the same and is self supported at a distance which is conductive to the formation of a corona between the aluminum foil and the grounded electrode.
  • the mechanism for this phenomena is not understood but may be related to electrostatic forces.
  • the foil electrode has a thickness of from 0.1 to 1.0 mil.
  • the foil thickness is not necessarily limitative so long as the sheet is flexible enough to permit the formation of a substantially uniform corona. The mechanism for this phenomenon is not known but apparently is related to the vibration of the sheet.
  • the width of the electrode should be suflicient to cover the film and the length is preferably at least 1 inch, more preferably 1 inch to /2 the electrode circumference.
  • the distance between the aluminum foil and the grounded electrode during treatment is generally less than inch, preferably in the range of from to 3 inch. Prior to treatment the foil should be positioned about to 1 inch from the grounded electrode.
  • the aluminum foil electrode 13 is connected to a power source (not shown) through electrical conduit 15.
  • the grounded electrode is grounded through conduit 17.
  • the sintered electrode 20 is shown in cross section in FIGURE 2 in lieu of aluminum .foil electrode 13 shown in FIGURE 1.
  • the sintered electrode may be supported by any suitable means. However, in contrast to the aluminum foil electrode, the sintered electrode is relatively thick, does not vibrate and does not seek the corona-producing distance. Since the sintered electrode is a porous metallic material, gases may be introduced through the electrode into the space between the electrodes. Apparent ly the sintered electrode provides for a large number of peaks or points which uniformly distribute the corona 22 throughout the space.
  • the invention is not limited to the particular type of product being treated by the corona, however, the invention is particularly applicable to the treatment of filmlike materials including all organic thermoplastic and thermosetting resins such as, but not limited to, polyolefins, including polyethylene, polypropylene, polybutene-l and the like, polyvinyls, vinyl-chloride copolymers, polyamides, including nylon, and the like.
  • polymer as employed herein includes homopolymers, copolymers, te-rpolymers, block copolymers, laminates and the like.
  • the film may be irradiated and/ or molecularly oriented.
  • the film thickness is not critical but is preferably between 0.1 and 20 mils.
  • the frequency is in the range of 10 to 1000 -kc., more preferably 100 to 300 -kc.
  • the voltage and current are variable over a wide range and are sufiicient to provide a corona discharge for the gap employed between the film and the charging electrode.
  • Suitable voltages are in excess of 100, preferably 500 to 10,000 kc.
  • Suitable currents are in excess of 0.7 amps, preferably 1 to 1.5 amps.
  • the lower electrode may be covered by any suitable buffer dielectric material as hereinbefore described.
  • Example I Using a high frequency high voltage generator Model HFSG-Z as the power source, an aluminum foil electrode measuring 18%" Wide x 5" long X 0.5 mil thick was separated from a inch thick rubber covered ground roll by a & fiberglass screen. A .75 mil polypropylene (Profax 6420) film and a .75 mil polyethylene (Alathon 1412) film passed between the rubber covered ground roll and the fiberglass screen.
  • Example 11 Using a high frequency high voltage generator, Model HFGS-2, a sintered stainless steel electrode, measuring 18% wide x 5" long x /s thick, was spaced approximately from the A rubber covered ground roll while the film (see Example I) was passed between the electrodes.
  • Example 111 Using a high frequency high voltage generator, Model HFSG-Z, a polished aluminum electrode measuring 18% wide x long x A" thick was spaced approximately from the A1" rubber covered ground roll while the film (see Example I) was passed between the electrodes.
  • Example IV Using a high frequency high voltage generator, Model JFSG-Z, a steel blade electrode measuring 18%" wide x thick was spaced from a A" rubber covered ground roll while the film (see Example I) was passed between the electrodes.
  • Apparatus for corona treating film comprising, in combination:
  • Apparatus for corona treating film comprising, in
  • At least one of said electrodes comprising a flexible metal foil electrode minimumly supported, the remainder of the flexible electrode being unsupported and free to adjust itself to a corona producing distance upon the application of a potential across said electrodes, and
  • Apparatus for corona treating film comprising, in combination:
  • the charging electrode comprising a thin, flexible sheet of aluminum foil fixedly secured above said film the remainder of the foil being unsupported and free to adapt itself to a corona producing distance upon the application of a potential across said electrodes.

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  • Life Sciences & Earth Sciences (AREA)
  • Forests & Forestry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Treatments Of Macromolecular Shaped Articles (AREA)

Description

H. G. SCHIRMER CORONA TREATMENT OF INCLUDING A FLEXIBL Filed Au 3,346,480 POLYMER FILM E METAL FOIL ELECTRODE g. 26, 1964 Oct. 10, 1967 APPARATUS FOR Fig.1
22 CORONA DISCHARGE Fig.2
United States Patent Office assignor to W. R. New York, N.Y., a corporation of This invention relates to apparatus for the corona treatment of film.
It has previously been proposed to improve the printability of polyolefins, such as polyethylene, by subjecting said films to high voltage electrical discharge. In proposed prior processes the film is passed between a pair of electrodes having an extended surface area to which is ap plied a high value alternating potential sufficient to produce a diffuse corona between the electrodes. The corona is apparently caused by partial breakdown or ionization of the atmosphere around an electrode. The electrodes must be so spaced that the film surface is exposed to the corona. The electrodes may comprise a pair of fiat plates positioned parallel to one another. The electrodes may also comprise a drum having a stator spaced apart and concentric therewith. There may also be positioned between the electrodes a sheet of dielectric material to prevent an arc-over and damage to the film being treated in the event that said film has pin holes or other weak spots therein. The dielectric covering also prevents pitting of the electrode and helps to spread the corona over the entire width of the electrode and causes the film to be a minor portion of the total dielectric in the gap. Suitable dielectrics for ground roll coverings are glass, Mylar, epoxy resins and elastomers, such as chlorosulfonated polyethylene, silicone rubber and the like, and anodized coatings. The elastomers are generally preferred since the only maintenance required is that it be kept free of any surface irregularities to prevent treat-through.
One of the difliculties with a blade or area type electrode has been achieving a uniform corona over the entire film surface. Generally, it is believed that the electrical discharge is effected at sharp edges. If the electrode has points and peaks which are closer to the discharged electrodes, the discharge will preferentially take place at these points resulting in spotty corona treatment.
It is an object of the invention to provide apparatus for the corona treatment of film.
It is another object of the invention to provide apparatus for the production of an electrical discharge.
Still another object of the invention is to provide apparatus for the formation of a corona.
These and other objects of the invention will be readily apparent to those skilled in the art from the accompanying disclosure, drawings and appended claims.
It has now been surprisingly found that a thin, flexible, electrically conductive, area electrode, for example, aluminum foil, in conjunction with a discharging electrode will produce a uniform electrical discharge and corona if a high-value alternating potential is applied across said electrodes. Further, if the flexible electrode is minimumly supported so that the remainder of the electrode is unsupported, said electrode will adjust itself to a coronaproducing distance from the discharging electrode.
In another embodiment of the invention the charging electrode may comprise an arcuate plate electrode composed of a sintered metal.
FIGURE 1 is a perspective view of a suitable embodiment employing an aluminum foil electrode for the corona treatment of thermoplastic film such as polyethylene or polypropylene.
FIGURE 2 is a cross section of a sintered arcuate 3,345,48fi Patented Oct. 10, 1967 plate electrode employed in lieu of the aluminum foil electrode shown in FIGURE 1.
The invention is best described with reference to the drawings. In this type of apparatus, which is shown as enclosed within a framework 2 but which may employ any suitable frame structure, is a grounded steel cylindrical electrode 4 mounted on a shaft 6 driven by any suitable driving means such as motor 8. The opposite end may be mounted onto the framework by any suitable means such as a journal box 10. The exterior surface of the grounded electrode 4 is preferably, but not necessarily, covered with an insulating substance 12, such as rubber. Although the direction of rotation is not important, the grounded electrode is shown as rotating in the clockwise position looking from the motor end of the shaft. The film 14 enters the frame 2 through a slot 3, passes under guide roller 5, over electrode 4 and under guide roller 7.
Mounted directly above the ground electrode is a thin, flexible, electrically conductive smooth sheet-like material, such as aluminum foil, which may be attached to any suitably supporting means 9 or to a blade electrode (not shown). The aluminum foil may be attached at any suitable location on the foil such as at the middle portion or at any edge, for example, the posterior edge relative to the movement of the film. However, the foil can be supported at only one point or in any plane transverse the moving web. Upon the application of a potential across the electrodes, the aluminum foil is attracted to the grounded electrode but does not contact the same and is self supported at a distance which is conductive to the formation of a corona between the aluminum foil and the grounded electrode. The mechanism for this phenomena is not understood but may be related to electrostatic forces.
Although the invention is discussed herein primarily with reference to the employment of a thin sheet of aluminum foil, it is to be understood that any electrically conductive material may be employed, for example thin flexible sheets of copper, iron, steel, brass, and the like. However, it is also within the scope of the invention to employ a wrinkled sheet of foil. Preferably, the foil electrode has a thickness of from 0.1 to 1.0 mil. However, the foil thickness is not necessarily limitative so long as the sheet is flexible enough to permit the formation of a substantially uniform corona. The mechanism for this phenomenon is not known but apparently is related to the vibration of the sheet. The width of the electrode should be suflicient to cover the film and the length is preferably at least 1 inch, more preferably 1 inch to /2 the electrode circumference. The distance between the aluminum foil and the grounded electrode during treatment is generally less than inch, preferably in the range of from to 3 inch. Prior to treatment the foil should be positioned about to 1 inch from the grounded electrode. The aluminum foil electrode 13 is connected to a power source (not shown) through electrical conduit 15. The grounded electrode is grounded through conduit 17.
The sintered electrode 20 is shown in cross section in FIGURE 2 in lieu of aluminum .foil electrode 13 shown in FIGURE 1. The sintered electrode may be supported by any suitable means. However, in contrast to the aluminum foil electrode, the sintered electrode is relatively thick, does not vibrate and does not seek the corona-producing distance. Since the sintered electrode is a porous metallic material, gases may be introduced through the electrode into the space between the electrodes. Apparent ly the sintered electrode provides for a large number of peaks or points which uniformly distribute the corona 22 throughout the space.
Although the invention has been described with reference to the employment of the aluminum foil and the sintered metal electrodes as the charging electrodes, it is within the scope of the invention to employ these electrodes as the discharging electrodes or to employ them as both electrodes or in any combination thereof.
The invention is not limited to the particular type of product being treated by the corona, however, the invention is particularly applicable to the treatment of filmlike materials including all organic thermoplastic and thermosetting resins such as, but not limited to, polyolefins, including polyethylene, polypropylene, polybutene-l and the like, polyvinyls, vinyl-chloride copolymers, polyamides, including nylon, and the like. The term polymer as employed herein includes homopolymers, copolymers, te-rpolymers, block copolymers, laminates and the like. The film may be irradiated and/ or molecularly oriented. The film thickness is not critical but is preferably between 0.1 and 20 mils.
referably the frequency is in the range of 10 to 1000 -kc., more preferably 100 to 300 -kc. The voltage and current are variable over a wide range and are sufiicient to provide a corona discharge for the gap employed between the film and the charging electrode. Suitable voltages are in excess of 100, preferably 500 to 10,000 kc. Suitable currents are in excess of 0.7 amps, preferably 1 to 1.5 amps.
The lower electrode may be covered by any suitable buffer dielectric material as hereinbefore described.
The invention is best described with reference to the following examples:
Example I Using a high frequency high voltage generator Model HFSG-Z as the power source, an aluminum foil electrode measuring 18%" Wide x 5" long X 0.5 mil thick was separated from a inch thick rubber covered ground roll by a & fiberglass screen. A .75 mil polypropylene (Profax 6420) film and a .75 mil polyethylene (Alathon 1412) film passed between the rubber covered ground roll and the fiberglass screen.
Current amps Watts 1100 Film speed -f.p.m 151 Resalt.--There was no breakdown of film and a uniform oxidation pattern was produced over the surface of electrode indicating a uniform corona (oxidation pattern as left by corona).
Example 11 Using a high frequency high voltage generator, Model HFGS-2, a sintered stainless steel electrode, measuring 18% wide x 5" long x /s thick, was spaced approximately from the A rubber covered ground roll while the film (see Example I) was passed between the electrodes.
Current amps 1.3 Watts 1100 Film speed f.p.m 150 Results.N breakdown of film and a uniform oxidation pattern over surf-ace of electrode.
Example 111 Using a high frequency high voltage generator, Model HFSG-Z, a polished aluminum electrode measuring 18% wide x long x A" thick was spaced approximately from the A1" rubber covered ground roll while the film (see Example I) was passed between the electrodes.
Current amps 1.4 Watts 1100 Film speed f.p.m 150 Resalts.-Some scorching of the film and a non-uniform oxidation pattern over the surface of electrode thus indicating that a non-uniform corona was produced.
4 Example IV Using a high frequency high voltage generator, Model JFSG-Z, a steel blade electrode measuring 18%" wide x thick was spaced from a A" rubber covered ground roll while the film (see Example I) was passed between the electrodes.
Current amps .9 Watts 300 Film speed f.p.m
Resalts.-There was much scorching of film.
While certain examples, structures, composition and process steps have been described for purposes of illustration, the invention is not limited to these. Variation and modification within the scope of the disclosure and the claims can readily be effected by those skilled in the art.
I claim:
1. Apparatus for corona treating film comprising, in combination:
(a) at least two spaced apart electrodes chargeable to opposite polarities,
(b) means for applying a high value alternating potential across said electrodes sufiicient to form a corona therebetween, and
(c) .at least one of said electrodes comprising a flexible metal foil electrode free to adjust itself to a substantially constant corona producing distance from the opposite electrode, and
(d) means for passing said film between said electrodes.
2. Apparatus for corona treating film comprising, in
combination:
(a) at least two spaced apart electrodes chargeable to opposite polarities,
(b) means for applying a high value alternating potential across said electrodes suflicient to form a corona between said electrodes,
(c) at least one of said electrodes comprising a flexible metal foil electrode minimumly supported, the remainder of the flexible electrode being unsupported and free to adjust itself to a corona producing distance upon the application of a potential across said electrodes, and
((1) means for passing said film between said electrodes.
3. The apparatus of claim 2 wherein said flexible electrode is aluminum foil.
4. The apparatus of claim 2 wherein said flexible electrode is supported by attaching an edge of said flexible electrode to a blade electrode.
5. Apparatus for corona treating film comprising, in combination:
(a) a pair of spaced apart electrodes chargeable to opposite polarities,
(b) means for continuously passing a film between said electrodes,
(c) means for applying a high value alternating potential across said electrodes,
(d) the discharging elect-rode comprising a grounded metal roller,
(e) the charging electrode comprising a thin, flexible sheet of aluminum foil fixedly secured above said film the remainder of the foil being unsupported and free to adapt itself to a corona producing distance upon the application of a potential across said electrodes.
References Cited UNITED STATES PATENTS 2,969,463 1/1961 McDonald 204-1 6 5 3,068,510 12/1962 Coleman 20f1:-165
JOHN H. MACK, Primary Examiner.
ROBERT K. MIHALEK, Examiner.

Claims (1)

1. APPARATUS FOR CORONA TREATING FILM COMPRISING, IN COMBINATION: (A) AT LEAST TWO SPACED APART ELECTRODES CHARGEABLE TO OPPOSITE POLARITIES, (B) MEANS FOR APPLYING A HIGH VALUE ALTERNATING POTENTIAL ACROSS SAID ELECTRODES SUFFICIENT TO FORM A CORONA THEREBETWEEN, AND (C) AT LEAST ONE OF SAID ELECTRODES COMPRISING A FLEXIBLE METAL FOIL ELECTRODE FREE TO ADJUST ITSELF TO A SUBSTANTIALLY CONSTANT CORONA PRODUCING DISTANCE FROM THE OPPOSITE ELECTRODE, AND (D) MEANS FOR PASSING SAID FILM BETWEEN SAID ELECTRODES.
US392147A 1964-08-26 1964-08-26 Apparatus for corona treatment of polymer film including a flexible metal foil electrode Expired - Lifetime US3346480A (en)

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US392147A US3346480A (en) 1964-08-26 1964-08-26 Apparatus for corona treatment of polymer film including a flexible metal foil electrode
GB33858/65A GB1112196A (en) 1964-08-26 1965-08-06 Apparatus for corona treatment of film
DE19651504332 DE1504332A1 (en) 1964-08-26 1965-08-19 Device for treating foils with a corona discharge
FR29483A FR1445321A (en) 1964-08-26 1965-08-26 Apparatus for processing films by electric discharge
US688629A US3405052A (en) 1964-08-26 1967-07-12 Apparatus for corona treatment of film including a porous sintered metal electrode

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108819192A (en) * 2018-03-29 2018-11-16 何佳遥 Device for PVC film processing
CN114103484A (en) * 2021-12-30 2022-03-01 安徽金日包装有限公司 Corona device for label ink jet printer

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2969463A (en) * 1957-05-03 1961-01-24 Plastics-treating apparatus
US3068510A (en) * 1959-12-14 1962-12-18 Radiation Res Corp Polymerizing method and apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2969463A (en) * 1957-05-03 1961-01-24 Plastics-treating apparatus
US3068510A (en) * 1959-12-14 1962-12-18 Radiation Res Corp Polymerizing method and apparatus

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108819192A (en) * 2018-03-29 2018-11-16 何佳遥 Device for PVC film processing
CN108819192B (en) * 2018-03-29 2021-01-05 杭州新天地彩印包装有限公司 Device for processing PVC (polyvinyl chloride) film
CN114103484A (en) * 2021-12-30 2022-03-01 安徽金日包装有限公司 Corona device for label ink jet printer
CN114103484B (en) * 2021-12-30 2023-01-03 安徽金日包装有限公司 Corona device for label ink jet printer

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