JPH07166490A - Heating-type supporting roll apparatus and its preparation - Google Patents

Abstract

PURPOSE: To prevent fibers of a passing web from adhering to a cylindrical heating rotator and exfoliating by covering the outer periphery of the rotator with a coating containing a mixture of chrome and polytetrafluoroethylene. CONSTITUTION: The coating 22 to cover the outside surface of the cylindrical rotator main body 18 made of steel or cast iron comprises a mixture of chrome and polytetrafluoroethylene of by weight (15-55):(45-85), preferably (55-45):(45:55), (15-25):(75-85) or (25-35):(65-75), and is formed by grinding so that small lumps of chrome are exposed on the surface containing the mixture. A web 16 such as paper and a liner board is guided to the recessed surface 30 of a stretching press part 14 formed by the coating 22 of the rotator main body 10 heated to 180-650 deg.F through an induction heater 26, a stretching shoe 12 and an endless blanket 28 to subject to the heating, stretching and pressing treatment and then pulled out smoothly without preventing fibers from being torn off from the web 16.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a heated support roll apparatus which cooperates with an extension shoe to form an extension press section therethrough for passing the web therethrough, and more particularly, the invention relates to a web wherein the web is the surface of the support roll. Of a heated extension nip press such that it is placed in physical contact with a portion of the.

[0002]

2. Description of the Related Art Currently, about 80 stretching nip presses are in operation worldwide.

Stretch nip presses basically have a support roll that cooperates with a stretch shoe to form a stretch press section between which the web passes. Also extending through the press section is a loop-type support blanket that slidably contacts a concave surface formed by the shoe such that the web extends with the blanket through the press section.

Stretching nip press equipment has a great advantage over conventional roll-coupled presses, ie, roll-coupled presses having at least two oppositely rotating press rolls forming a press nip therebetween. Have.

The primary effect of stretch nip presses is to increase the dwell time of the web as it passes through the press section.

Recently, investigations have been conducted in an effort to further improve the dewatering capacity of stretch nip presses. In particular, by heating the support roll to an elevated temperature, the water vapor generated in the stretch press section serves to remove the water remaining on the web in liquid form from the web. Typically,
The support roll is heated by an induction heater or the like.
However, the above-mentioned so-called heat type nip press or high temperature press (HTP) has a problem in that the pressed web tends to stick to the outer surface of the support roll downstream of the stretching press portion.

Moreover, the individual fibers within the pressed web tend to stick to the heated surface of the support roll downstream of the stretch press section, thus causing "fiber pickin".
A phenomenon known as "g)" will occur.

All of the above problems lead to poor quality for efficient production of pressed paper webs and liner boards.

[0009] In more severe situations, as the web exits the press section, the web undergoes delamination, one layer of the pressed web is fed from the press section to a dryer section downstream thereof, and the other layers of the pressed web are supported rolls. May adhere to the roll and remain in contact with the roll.

Various attempts have hitherto been made to overcome the above-mentioned problems.

One way to overcome the aforementioned problems is to spray a release agent spray layer onto the upstream surface of the heated support rolls. However, such release agents are not only relatively expensive, but can sometimes adversely affect the pressed web. Further, the operation of evenly mounting the release agent on the heating type support roll is relatively complicated.

Various experiments have been carried out with steel support rolls having a chrome-plated surface. However, such chrome surfaces have not been successful in evenly releasing the pressed web.

[0013]

SUMMARY OF THE INVENTION The present invention therefore provides a coating comprising a matrix of chromium and polytetrafluoroethylene (trade name Teflon) which readily releases the pressed web from the surface of a heated support roll. It is very effective in terms of doing. Teflon is E. Eye. Dupont De Nemours & Company (EI Du Pont De Nemours
& Company) is a registered trademark of the United States.

Accordingly, a first object of the present invention is to provide a heated support roll and a method of making such a support roll which significantly contributes to the technique of pressing a web of paper or linerboard.

Another object of the present invention is to provide a heated support roll apparatus containing a coating of chromium and polytetrafluoroethylene.

Another object of the present invention is to provide a support roll apparatus having an outer surface having a matrix coating of chromium and polytetrafluoroethylene, the coating being abraded to provide chromium agglomerates within the matrix. To be exposed.

Other objects and advantages of the present invention will be readily apparent to those skilled in the art upon consideration of the detailed description set forth below in connection with the accompanying drawings.

[0018]

SUMMARY OF THE INVENTION The present invention is directed to a heated support roll apparatus and a method of making the apparatus. The support roll apparatus cooperates with the extension shoe to form an extension press section therethrough for passing the paper web or linerboard web. The roll device has a cylindrical rotating body forming an outer peripheral surface. A coating is applied to the outer surface of the body and is placed in press contact with the web while the web passes through the press section. The coating has the property of preventing the web from sticking to the coating after the web has passed through the press section. This coating consists of a mixture of chromium and polytetrafluoroethylene.

In particular, in one embodiment of the invention, the cylindrical body is made of steel, and in another embodiment of the invention, the cylindrical body is made of cast iron.

The coating is mounted as a matrix on the outer surface of the body, and the coating is designed to prevent snagging of fibers disposed within the web.

The coating comprises 15-55% by weight chromium and 45-85% by weight polytetrafluoroethylene.

In one embodiment of the invention, the coating comprises 55-45% by weight chromium and 45-5% by weight.
Contains 5% polytetrafluoroethylene.

In another embodiment of the invention, the coating comprises 15-25% by weight chromium and 75-85% by weight polytetrafluoroethylene.

In a preferred embodiment of the invention, the coating comprises 25-35% by weight chromium and 6% by weight.
5 to 75% polytetrafluoroethylene.

In each of the foregoing embodiments of the present invention, the cylindrical body and coating were heated to a temperature of 180 ° to 650 ° F and the support roll was rotated at a peripheral speed of up to 6,000 feet per minute.

In another embodiment of the invention, the coating comprises a mixture of chromium and ceramic material.

In another embodiment of the present invention, the coating comprises a mixture of chromium and zirconia.

In yet another embodiment of the present invention, the heated roll cooperates with the press roll and the support roll apparatus comprises a coating having a mixture of chromium and polytetrafluoroethylene.

The present invention also provides a method of making a heated support roll that cooperates with an extension shoe to form an extension press section between which the web is passed. The method includes applying a coating to the outer surface of a cylindrical rotating body. When using a support roll machine, the coating is placed in press contact with the web while the web passes through the press section. The coating has the property of preventing the web from sticking to the coating after the web has passed through the press section. This coating contains a mixture of chromium and polytetrafluoroethylene.

In addition, the method exposes a certain percentage of the chromium nodules in the mixture of chromium and polytetrafluoroethylene, with the remaining portion of the mixture between the chromium nodules being polytetrafluoroethylene. And polishing the coating prior to using the support roll apparatus.

The polishing step also further includes polishing the coating with a doctor blade that is pressed to doctor the coating.

Many variations and modifications of this invention will become readily apparent to those of ordinary skill in the art upon consideration of the detailed description set forth in connection with the accompanying drawings. However, such variations and modifications are included within the spirit and scope of the invention as limited by the claims.

Included among such variations and modifications are amorphous coatings on the support roll, which amorphous coatings include iron-based alloys. In particular, the iron-based alloy contains iron, chromium and boron.

The amorphous coating consists of a plasma sprayed onto a cylindrical body. The amorphous nature of this alloy is caused by a special hardening phenomenon. Such hardening phenomena include a change from a dual phase crystal alloy to a complex and stable amorphous hardened surface alloy with corrosion resistance and wear resistance.

Various tests have shown that such amorphous coatings do not stick.

In another variant of the invention, the coating is a matrix of ceramic and polytetrafluoroethylene, in which case the voids, ie the pores of the ceramic material, are filled with polytetrafluoroethylene.

In particular, this ceramic is aluminum oxide and titanium oxide, the rest being polytetrafluoroethylene. In this example, the exposed portion of polytetrafluoroethylene is 67% of the total surface area, and in another example, 37% of the surface is polytetrafluoroethylene.

The basic feature of such coatings is that the pressed web does not stick to the surface of the support roll.

[0039]

DETAILED DESCRIPTION OF THE INVENTION Throughout the various embodiments of the present invention, like numerals refer to like parts.

FIG. 1 is a side view of a heating and supporting roll apparatus, generally designated by the numeral 10, which comprises an extension shoe 12
Co-act with to form an elongated pressure portion 14 therebetween, through which the web 16 passes. The roll device 10 has a rotatable cylindrical rotating body 18, which has an outer peripheral surface 2
Form 0.

The outer surface 20 of the cylindrical body 18 is provided with a coating 22, which is arranged in press contact with the web 16 during its passage through the press section 14. Its coating 22
Has properties such that the web 16 does not stick to the coating 22 as it passes through the press portion 14. The coating 22 comprises a mixture of chromium and polytetrafluoroethylene.

In one embodiment of the invention, the cylindrical body 1
8 is made of steel, but in another embodiment of the invention the cylindrical body is made of cast iron.

The coating 22 is applied as a matrix to the outer surface 20 of the body 18. The coating 22 is structured so that it does not trap fibers in the web 16.

In one embodiment of the invention, coating 22 comprises 15-55% chromium by weight and 45% by weight.
˜85% polytetrafluoroethylene.

In another embodiment of the invention, coating 22 comprises 55-45% by weight chromium and 45-55% by weight polytetrafluoroethylene.

In another embodiment of the invention, the coating 22 comprises 15-25% by weight chromium and 75-85% by weight polytetrafluoroethylene.

In the preferred embodiment of the present invention, coating 22 comprises 25-35% by weight chromium and 65-75% by weight polytetrafluoroethylene.

A coating containing 30% chromium and 70% polytetrafluoroethylene was very effective in preventing delamination. The support roll was heated to 600 ° F, at which time the solids content was 34% as it flowed into the pressed portion of the formed web. The pressed web had a solids content of 50-70% at the time of outflow and no linerboard delamination occurred.

The support roll system 10 having the cylindrical body 18 and coating 22 is heated to a temperature of 180 ° to 650 ° F and the support roll system 10 rotates at peripheral speeds of up to 6,000 feet per minute.

In another embodiment of the present invention, coating 22 comprises a mixture of chromium and ceramic material.

In particular, in another embodiment of the present invention, coating 22 comprises a mixture of chromium and zirconia.

Further, as shown in FIG. 1, the coating 22 and the cylindrical body 18 are heated by the induction heater 26.

A looped support blanket 28 also extends through the press portion 14 and the blanket slidably cooperates with the concave surface 30 formed by the extension shoe 12.

A press felt 32 is arranged between the blanket 28 and the web 16, which is the web 16
Absorbs water exiting the web 16 as they pass through the stretch press section 14.

In another embodiment of the invention, shown in FIG. 2, the shoe 12 is replaced by conventional press rolls 12A with a press portion 14A formed therebetween for passing a web 16A. Coating 22A comprises a mixture of chromium and polytetrafluoroethylene.

FIG. 3 is an enlarged sectional view showing how the heating and supporting roll device 10 is manufactured. The roll device 10 cooperates with the extension shoes 12 to form therebetween an extension press portion 14 through which the web 16 passes. In this method, when the support roll device 10 is used, the web 1
Applying a coating, generally indicated at 22, to the outer surface 20 of the cylindrical rotating body 18 such that the coating 22 is placed in press contact with the web 16 as the 6 passes through the press section 14. . The coating 22 has the property of preventing the web 16 from sticking to the coating 22 after the web 16 has been fed through the press section 14. Coating 22 comprises a mixture of chromium and polytetrafluoroethylene.

As shown in FIG. 3, the coating 22 is a support roll apparatus 10 such that a percentage of the chromium nodules 34, exaggerated for clarity, are exposed in the mixture of chromium and polytetrafluoroethylene. Is polished before using. Such nodules 34 are exposed by the polishing and the remainder of the mixture between the chromium nodules is polytetrafluoroethylene 36.

In particular, the polishing step is performed by coating 22
Polishing the coating 22 with a doctor blade 24 that is pressed in a doctoring relationship against.

[0059]

As described above in detail, in the heating type support roll according to the present invention, effective characteristics for preventing the web after passing through the press from sticking to the outer surface which is in contact with the web by the press. Since the coating having the above is applied, the web after leaving the press is prevented from sticking to the roll, and the object of fiber catching on the supporting roll and delamination, which have been conventionally problems, are prevented.

Further, according to the present invention, the coating formed on the surface of the supporting roll is made relatively inexpensive by using a mixture of chromium and polytetrafluoroethylene, a mixture of chromium and ceramics material, a mixture of chromium and zirconia, and the like. Can be formed.

[Brief description of drawings]

FIG. 1 is a side view of the heated support roll apparatus of the present invention showing an extension shoe that forms an extension press section through which the web passes, with the support roll.

FIG. 2 is a side view of another embodiment of the present invention in which a heated support roll apparatus cooperates with press rolls to form a press section there between for web passage.

FIG. 3 is an enlarged cross-sectional view of the heated support roll shown in FIG. 1, showing a method of polishing a coating prior to its use with a doctor blade that is pressed in a doctoring relationship against the coating.

[Explanation of symbols]

 10 Heat-supporting roll device 12 Elongation shoe 14 Press part 16 Web 18 Cylindrical rotating body 22 Coating 24 Doctor blade 26 Induction heater 28 Blanket 30 Concave surface 34 Chromium blob 36 Polytetrafluoroethylene

Claims (17)

[Claims] 1. A cylindrical rotating body forming an outer peripheral surface, and a coating mounted on the outer surface of the body,
The same coating is applied while the web passes through the press section.
A web that is placed in press contact with the web and that has the property of preventing the web from sticking to the coating after the web has passed through the press section, the coating comprising a mixture of chromium and polytetrafluoroethylene. A heated support roll device that cooperates with the shoe to form an elongate press section between the shoe and the web. 2. The heated support roll apparatus according to claim 1, wherein the cylindrical body is made of steel. 3. The heating type support roll device according to claim 1, wherein the cylindrical body is made of cast iron. 4. The coating according to claim 1, wherein the coating is mounted as a matrix on the outer surface of the body, and the coating is structured so as not to catch fibers arranged in the web. Heating type support roll device. 5. The coating has a weight ratio of 15-5.
The heating type support roll device according to claim 1, comprising 5% of chromium and 45 to 85% by weight of polytetrafluoroethylene. 6. The coating has a weight ratio of 55-4.
The heated support roll apparatus according to claim 1, comprising 5% chromium and 45 to 55% by weight of polytetrafluoroethylene. 7. The coating has a weight ratio of 15-2.
The heating type support roll device according to claim 1, comprising 5% of chromium and 75-85% by weight of polytetrafluoroethylene. 8. The coating has a weight ratio of 25-3.
The heating type support roll device according to claim 1, comprising 5% chromium and 65 to 75% by weight of polytetrafluoroethylene. 9. The cylindrical body and coating are 180
The heating type support roll device according to claim 1, wherein the heating type support roll device is heated to a temperature of ° to 650 ° F. 10. A cylindrical rotating body forming an outer peripheral surface, and a coating mounted on the outer surface of the body,
The coating is placed in press contact with the web during passage of the web through the press portion to prevent the web from sticking to the coating after the web passes through the press portion, and the coating comprises , A heated support roll apparatus comprising a mixture of chromium and a ceramic material that cooperates with an extension shoe to form an extension press portion therebetween for passing a web. 11. A cylindrical rotating body forming an outer peripheral surface, and a coating mounted on the outer surface of the body,
The coating is placed in press contact with the web while the web passes through the press portion and has the property of preventing the web from sticking to the coating after the web has passed through the press portion, and A heated support roll apparatus wherein the coating comprises a mixture of chromium and zirconia to cooperate with an extension shoe to form an extension press portion therethrough for passing the web. 12. A cylindrical rotating body forming an outer peripheral surface, and a coating mounted on the outer surface of the body,
The coating is arranged to be in press contact with the web while the web passes through the press portion, and has the property of preventing the web from sticking to the coating after the web has passed through the press portion, and The coating comprises a mixture of chromium and polytetrafluoroethylene, a heated support roll apparatus that cooperates with a press roll to form a press portion therethrough of the web. 13. A cylindrical rotating body forming an outer peripheral surface, and a coating mounted on the outer surface of the body,
The coating is placed in press contact with the web during passage of the web through the press portion to prevent the web from sticking to the coating after the web passes through the press portion, and the coating is An amorphous alloy, said amorphous alloy comprising a mixture of iron, chromium and boron, in combination with an elongation shoe, so as to form a press portion there between for passing the web. Support roll device. 14. A cylindrical rotating body forming an outer peripheral surface, and a coating mounted on the outer surface of the body,
The coating has a property of being placed in press contact with the web during passage of the web through the press portion and preventing the web from sticking to the coating after the web passes through the press portion. Is a heated support roll apparatus comprising a mixture of ceramic and polytetrafluoroethylene adapted to cooperate with an extension shoe to form an extension press portion therethrough for passage of the web. 15. Use of a coating on the outer surface of a cylindrical rotating body such that, when the support roll apparatus is in use, the coating is placed in press contact with the web while the web passes through the press section. , The coating having the property of preventing the web from sticking to the coating after the web has passed through the press section, comprising a mixture of chromium and polytetrafluoroethylene, in cooperation with an extension shoe, , A method of making a heated support roll apparatus so as to form a stretch press portion for passing a web. 16. A high percentage of chromium nodules in a mixture of chromium and polytetrafluoroethylene are exposed, such that the balance between the chromium nodules is composed of polytetrafluoroethylene. The method of claim 15, further comprising the step of polishing the coating prior to use of the support roll apparatus. 17. The method of claim 16, wherein the polishing step comprises polishing the coating with a doctor blade that is pressed in a doctoring relationship against the coating.