CA1205335A - Method of manufacturing an endless resin impregnated belt - Google Patents
Method of manufacturing an endless resin impregnated beltInfo
- Publication number
- CA1205335A CA1205335A CA000470970A CA470970A CA1205335A CA 1205335 A CA1205335 A CA 1205335A CA 000470970 A CA000470970 A CA 000470970A CA 470970 A CA470970 A CA 470970A CA 1205335 A CA1205335 A CA 1205335A
- Authority
- CA
- Canada
- Prior art keywords
- belt
- fabric
- resin
- endless
- manufacturing
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A method for manufacturing an endless belt for use in an extended paper press nip is described which comprises providing the endless base fabric, coating and impregnating of polymeric resin by doctoring into the fabric and curing said resin to form a smooth surface.
A method for manufacturing an endless belt for use in an extended paper press nip is described which comprises providing the endless base fabric, coating and impregnating of polymeric resin by doctoring into the fabric and curing said resin to form a smooth surface.
Description
~Z~S3~
The field of the invention relates to a method of manufacturing an endless belt particularly for use in an extended press nip.
During the papermaking process, a web is formed by depositing a fibrous slurry on a forming wire. A large amount of water is drained from the slurry during this process, after which the newly-formed web proceeds to a press section.
~he press section includes a series of press nips. The web finally proceeds to a drying section including heated dryer drums where the water content is reduced to a desirable level.
In view of the high cost of energy, it is desirable to remove as much water as possible from the web prior to its entering the drying section. m e dryer drums in this section are often heated by steam and costs can be substantial if a large amount of water needs to be removed.
The use of extended press nips has been found to be advantageous over the use of nips formed by pairs of adjacent rollers. By extending the time the web is subjected to pressure in the nip, a greater amount of water can be removed. Ihis fact has been recognized by those skilled in the art, and several patents have been granted in the area.
~hese patents include Re. 30,268, 4,201,624, 4,229,253 and 4,229,254.
In using extended press nips to dewater a fibrous web, the web has typically been sandwiched between two moisture-absorbing felts and a belt. The felts are trained around a cylindrical press roll with the web between them while the belt is arranged for applying pressure to the felts and roll. A pressure shoe exerts pressure on the belt in the press area.
l~k5~
A problem has been encountered during the dewatering of webs in extended nips. It has been found that a bulge developps in the belt ahead of the nip. This problem is recognized in U.S. Patent Nos. 4,229,253 and 4,229,254, and certain belt constructions are suggested for overcoming the problem.
m e belt comprises a base fabric which is impregnated with a thermoplastic or thermosetting polymeric material. me base fabric which can be single layer or multilayer, is sufficiently open to allow total irnpregnation of the material to eliminate any voids in the final fabric.
A significant advantage of this belt construction is that it can be made in any length since it does not require a mandrel during the manufacture thereof. ~ base fabric is provided endless using conventional fabric technology and then coated and impregnated with the polymeric material.
A method for manufacturing the endless belt comprises-coating and impregnating of polymeric resin by doctoring into the fabric and curing said resin to form a smooth surface.
m e resulting structure is both light in weight and sufficiently stable to operate under paper machine conditions. It has sufficient abrasion resistance to resist any wear that might take place in the extended nip apparatus.
Unlike materials which are built up in the manner of a rubber tire and can flow and/or delaminate, the invention provides a belt which will maintain its integrity. It also solves the problem of bulging near the press nips. ~le belt has a uniform smooth polymeric surface which is engaged by a pressure shoe applying pressure in the direction of -the roll.
S~ 5 Having thus generally described the nature of the invention, reference will now be made to the accompanyin~
drawings, showing by way of illustration, a preferred embodiment thereof, and in which:
Figure 1 is a side elevational view of an extended press nip according to the invention' Figure 2 is a partially sectional front view of the press nip shown in Figure 1, and Figure 3 is a sectional side elevational view of the belt employed in the invention.
An extended press nip is provided by the invention for dewatering a travelling web of material. m e nip 10 i9 defined by a cylindrical press roll 12, a pressure shoe 14 having an arcuate surface facing the press roll, and a belt 16 arranged such that it bears against the surface of the press roll. The arcuate surface of the pressure shoe has about the same radius of curvature as the press roll. m e distance between the press roll and the pressure shoe may ~e adjusted by means of conventional hydraulic or mechanical apparatus (not shown) connected to a rod 18 pivotally secured to the shoe 14. The rod may also be actuated to apply the desired pressure to the shoe.
It will be appreciated that the pressure shoe and press roll described above and shown in Figures 1 2 are conventional and that other arrangements may be utilized in accordance with the invention.
m e belt 16 employed in accordance with the invention is shown in detail in Figure 3. It has proven to be superior to belts currently known to the art both from an operational standpoint and for manufacturing considerations. The belt 16 comprises a base fabric 20 ~3;b53~S
which is impregnated with a polymeric material 22. Thermo-setting resins such as polyurethanes have been found to be suitable impregnating materials. Thermoplastic polymers such as polypropylene are also acceptable.
The base fabric 20 is sufficiently open to allow total impregnation. This eliminates the possibility of any voids forming in the final fabric which would allow the lubrication used between the belt and shoe to pass through the belt and contaminate the felt and fibrous web. It is endless in final construction and uniform in thickness.
m e fabric must also be made to have sufficient stability under paper machine conditions~ In other words, it must have length stability, width stability, and guideability. --me thermoplastic resin or thermosetting resin used, should be a substantially one hundred percent solid composition to avoid the formation of bubbles during the curing process of the resin in the belt structure.
Ihe belt has at least one smooth side 16' which contacts the pressure shoe 14.
Belts manufactured in accordance with the invention have been found to have many desirable characteristics. They move easily over the pressure shoe and are capable of trans-mitting pressure ~rom the shoe to the web and press roll.
Sufficient flexibility is obtained, and the belts have proven to be unaffected by lubricant applied prior to entering the press nip.
In comparison with belts currently known to the art, the invention provides a belt which is relatively thin and light in weight. Thick belts have the disadvantage of tending to flow while within the nip. For example a 24'6" x 170" belt impre-gnated with a thermosetting resin in accordance with the invention weighs about two hundred pounds. A similar size belt having bulge-resistant characteristics and having a structure defined in the above mentioned patents weighs about twelve hundred pounds. Unlike the heavier belts, the in-vention does not require a reinforcing structure.
m e manufacture of the belt according to the invention may be accomplished economically and without the need for mandrels or autoclaves which limit the size of other belts. A ~elt of any length can accordingly be produced. m e base structure is first woven. A web may be needled into the woven base if desired. If the base structure has not been woven endless it is then joined endless using conventional joining techniques applicable to forming fabrics in the paper industry. A polymeric material is then applied to the base fabric and forms a mechanical interlock therewith. The resin is allowed to cure for a sufficient period of time. After curing, the resin surface may be sanded or ground to provide a belt of uniform caliper having at least one smooth surface~
A belt made in accordance with this invention may be utilized with the apparatus shown in Figure 1. me belt 16 is positioned between the pressure shoe and the pressure roller. The smooth coated side 16' of the belt is engaged by the shoe. A fibrous web 24 carried between first and second felts 26 and 27 respectively is introduced into the press nip 10~ The side of the belt 16 engaging the shoe 14 is lubricated by lubricating means 28 positioned ahead of the nip.
The belt 16 is easily repaired should a hole or other surface irregularity develop therein. me damaged portion is cleaned with a solvent and a suitable amount o~
coating is applied with a blade. ~ heat gun is employed to cure the surface which can then be sanded.
~L2~:1b~3;~
Because of the excellent flexibility characteristics of the base structure and the fact that the coating can be kept to a minimu~, the surface of the belt will have less tendency to fail due to bending fatigue. mis is due to the fact that, because of the low caliper, the surface plane of the coated surface is at a minimum distance from the neutral axis of bending. mis reduces the percentage of elongation and compression at the surface plane during bending.
Example 1 A two-layered monofilament base fabric was flat woven, heat stabilized, and joined endless using normal joining techniques~ me fabric was then coated with a 100%
solid polyurethane resin Dupont Adiprene L 100 and cured.
The coating step may be accomplished through the use of a doctor blade or the like to obtain a smooth surface. If the outside surface of the base fabric is coated, it may be turned inside out for use in the application.
Example 2 A monofilament fabric is woven into a two layer 2G weave having sufficient openness. It is heatset and joined endless. The endless fabric is placed on a finishing machine including a pair of rollers. One of the rollers is an oil heated cylinder. A polyurethane sheet of proper uniform caliper is placed on the inside surface of the fabric and allowed to pass between the heated cylinder and the fabric structure. m e temperature of the oil cylinder is maintained at a substantially constant level to obtain uniform melting and fusing of the plastic film. The sheet is trimmed so that there is no overlap in the material to be pressed into the fabric structure. As the fabric and sheet pass around the heated cylinder, sufficient heat is maintained to cause ~Z~S3~5 the polyurethane to flow into the fabric~ A pressure roll may be used against the outside of the fabric to insure complete impreqnation. The polyurethane is plasticised and forced into the voids of the fabric.
A smooth surface is obtained which does not require any further finishing steps. The use of a 100% polymeric sheet also eliminates any problems which could develop in the finished fabric resulting from the use of an impregnation compound containing solvents or water. After the fabric has undergone the pressing operation, the edges are trimmed and sealed for operation in a paper-making machine.
Example 3 A monofilament polyester base fabric having sufficient openness for impregnation is provided. m e fabric is a two layer weave having both width and length stability. A polypropylene film having a thickness of about 0.020 inches or more is fused to the base fabric in the manner described in Example 2. m e temperature of the oil cylinder is maintained at a substantially constant level to obtain uniform melting and fusing of the plastic film. l~e base fabric has a higher melting temperature than the polypropylene film and is not dis-turbed by the heating process. After th~ fabric has undergone the pressing operation, the edges are trimmed and sealed for operation in a paper-making machine.
It will be appreciated that the belt utilized in the invention may include a base fabric made from various polymeric materials having the necessary properties for application in paper-making machines. Materials other than polyurethane and polypropylene may also be employed as the coating material.
~ 7 ---~C~ 3~
This application is a division of application Serial No. 411,393, filed September 14, 1982.
The field of the invention relates to a method of manufacturing an endless belt particularly for use in an extended press nip.
During the papermaking process, a web is formed by depositing a fibrous slurry on a forming wire. A large amount of water is drained from the slurry during this process, after which the newly-formed web proceeds to a press section.
~he press section includes a series of press nips. The web finally proceeds to a drying section including heated dryer drums where the water content is reduced to a desirable level.
In view of the high cost of energy, it is desirable to remove as much water as possible from the web prior to its entering the drying section. m e dryer drums in this section are often heated by steam and costs can be substantial if a large amount of water needs to be removed.
The use of extended press nips has been found to be advantageous over the use of nips formed by pairs of adjacent rollers. By extending the time the web is subjected to pressure in the nip, a greater amount of water can be removed. Ihis fact has been recognized by those skilled in the art, and several patents have been granted in the area.
~hese patents include Re. 30,268, 4,201,624, 4,229,253 and 4,229,254.
In using extended press nips to dewater a fibrous web, the web has typically been sandwiched between two moisture-absorbing felts and a belt. The felts are trained around a cylindrical press roll with the web between them while the belt is arranged for applying pressure to the felts and roll. A pressure shoe exerts pressure on the belt in the press area.
l~k5~
A problem has been encountered during the dewatering of webs in extended nips. It has been found that a bulge developps in the belt ahead of the nip. This problem is recognized in U.S. Patent Nos. 4,229,253 and 4,229,254, and certain belt constructions are suggested for overcoming the problem.
m e belt comprises a base fabric which is impregnated with a thermoplastic or thermosetting polymeric material. me base fabric which can be single layer or multilayer, is sufficiently open to allow total irnpregnation of the material to eliminate any voids in the final fabric.
A significant advantage of this belt construction is that it can be made in any length since it does not require a mandrel during the manufacture thereof. ~ base fabric is provided endless using conventional fabric technology and then coated and impregnated with the polymeric material.
A method for manufacturing the endless belt comprises-coating and impregnating of polymeric resin by doctoring into the fabric and curing said resin to form a smooth surface.
m e resulting structure is both light in weight and sufficiently stable to operate under paper machine conditions. It has sufficient abrasion resistance to resist any wear that might take place in the extended nip apparatus.
Unlike materials which are built up in the manner of a rubber tire and can flow and/or delaminate, the invention provides a belt which will maintain its integrity. It also solves the problem of bulging near the press nips. ~le belt has a uniform smooth polymeric surface which is engaged by a pressure shoe applying pressure in the direction of -the roll.
S~ 5 Having thus generally described the nature of the invention, reference will now be made to the accompanyin~
drawings, showing by way of illustration, a preferred embodiment thereof, and in which:
Figure 1 is a side elevational view of an extended press nip according to the invention' Figure 2 is a partially sectional front view of the press nip shown in Figure 1, and Figure 3 is a sectional side elevational view of the belt employed in the invention.
An extended press nip is provided by the invention for dewatering a travelling web of material. m e nip 10 i9 defined by a cylindrical press roll 12, a pressure shoe 14 having an arcuate surface facing the press roll, and a belt 16 arranged such that it bears against the surface of the press roll. The arcuate surface of the pressure shoe has about the same radius of curvature as the press roll. m e distance between the press roll and the pressure shoe may ~e adjusted by means of conventional hydraulic or mechanical apparatus (not shown) connected to a rod 18 pivotally secured to the shoe 14. The rod may also be actuated to apply the desired pressure to the shoe.
It will be appreciated that the pressure shoe and press roll described above and shown in Figures 1 2 are conventional and that other arrangements may be utilized in accordance with the invention.
m e belt 16 employed in accordance with the invention is shown in detail in Figure 3. It has proven to be superior to belts currently known to the art both from an operational standpoint and for manufacturing considerations. The belt 16 comprises a base fabric 20 ~3;b53~S
which is impregnated with a polymeric material 22. Thermo-setting resins such as polyurethanes have been found to be suitable impregnating materials. Thermoplastic polymers such as polypropylene are also acceptable.
The base fabric 20 is sufficiently open to allow total impregnation. This eliminates the possibility of any voids forming in the final fabric which would allow the lubrication used between the belt and shoe to pass through the belt and contaminate the felt and fibrous web. It is endless in final construction and uniform in thickness.
m e fabric must also be made to have sufficient stability under paper machine conditions~ In other words, it must have length stability, width stability, and guideability. --me thermoplastic resin or thermosetting resin used, should be a substantially one hundred percent solid composition to avoid the formation of bubbles during the curing process of the resin in the belt structure.
Ihe belt has at least one smooth side 16' which contacts the pressure shoe 14.
Belts manufactured in accordance with the invention have been found to have many desirable characteristics. They move easily over the pressure shoe and are capable of trans-mitting pressure ~rom the shoe to the web and press roll.
Sufficient flexibility is obtained, and the belts have proven to be unaffected by lubricant applied prior to entering the press nip.
In comparison with belts currently known to the art, the invention provides a belt which is relatively thin and light in weight. Thick belts have the disadvantage of tending to flow while within the nip. For example a 24'6" x 170" belt impre-gnated with a thermosetting resin in accordance with the invention weighs about two hundred pounds. A similar size belt having bulge-resistant characteristics and having a structure defined in the above mentioned patents weighs about twelve hundred pounds. Unlike the heavier belts, the in-vention does not require a reinforcing structure.
m e manufacture of the belt according to the invention may be accomplished economically and without the need for mandrels or autoclaves which limit the size of other belts. A ~elt of any length can accordingly be produced. m e base structure is first woven. A web may be needled into the woven base if desired. If the base structure has not been woven endless it is then joined endless using conventional joining techniques applicable to forming fabrics in the paper industry. A polymeric material is then applied to the base fabric and forms a mechanical interlock therewith. The resin is allowed to cure for a sufficient period of time. After curing, the resin surface may be sanded or ground to provide a belt of uniform caliper having at least one smooth surface~
A belt made in accordance with this invention may be utilized with the apparatus shown in Figure 1. me belt 16 is positioned between the pressure shoe and the pressure roller. The smooth coated side 16' of the belt is engaged by the shoe. A fibrous web 24 carried between first and second felts 26 and 27 respectively is introduced into the press nip 10~ The side of the belt 16 engaging the shoe 14 is lubricated by lubricating means 28 positioned ahead of the nip.
The belt 16 is easily repaired should a hole or other surface irregularity develop therein. me damaged portion is cleaned with a solvent and a suitable amount o~
coating is applied with a blade. ~ heat gun is employed to cure the surface which can then be sanded.
~L2~:1b~3;~
Because of the excellent flexibility characteristics of the base structure and the fact that the coating can be kept to a minimu~, the surface of the belt will have less tendency to fail due to bending fatigue. mis is due to the fact that, because of the low caliper, the surface plane of the coated surface is at a minimum distance from the neutral axis of bending. mis reduces the percentage of elongation and compression at the surface plane during bending.
Example 1 A two-layered monofilament base fabric was flat woven, heat stabilized, and joined endless using normal joining techniques~ me fabric was then coated with a 100%
solid polyurethane resin Dupont Adiprene L 100 and cured.
The coating step may be accomplished through the use of a doctor blade or the like to obtain a smooth surface. If the outside surface of the base fabric is coated, it may be turned inside out for use in the application.
Example 2 A monofilament fabric is woven into a two layer 2G weave having sufficient openness. It is heatset and joined endless. The endless fabric is placed on a finishing machine including a pair of rollers. One of the rollers is an oil heated cylinder. A polyurethane sheet of proper uniform caliper is placed on the inside surface of the fabric and allowed to pass between the heated cylinder and the fabric structure. m e temperature of the oil cylinder is maintained at a substantially constant level to obtain uniform melting and fusing of the plastic film. The sheet is trimmed so that there is no overlap in the material to be pressed into the fabric structure. As the fabric and sheet pass around the heated cylinder, sufficient heat is maintained to cause ~Z~S3~5 the polyurethane to flow into the fabric~ A pressure roll may be used against the outside of the fabric to insure complete impreqnation. The polyurethane is plasticised and forced into the voids of the fabric.
A smooth surface is obtained which does not require any further finishing steps. The use of a 100% polymeric sheet also eliminates any problems which could develop in the finished fabric resulting from the use of an impregnation compound containing solvents or water. After the fabric has undergone the pressing operation, the edges are trimmed and sealed for operation in a paper-making machine.
Example 3 A monofilament polyester base fabric having sufficient openness for impregnation is provided. m e fabric is a two layer weave having both width and length stability. A polypropylene film having a thickness of about 0.020 inches or more is fused to the base fabric in the manner described in Example 2. m e temperature of the oil cylinder is maintained at a substantially constant level to obtain uniform melting and fusing of the plastic film. l~e base fabric has a higher melting temperature than the polypropylene film and is not dis-turbed by the heating process. After th~ fabric has undergone the pressing operation, the edges are trimmed and sealed for operation in a paper-making machine.
It will be appreciated that the belt utilized in the invention may include a base fabric made from various polymeric materials having the necessary properties for application in paper-making machines. Materials other than polyurethane and polypropylene may also be employed as the coating material.
~ 7 ---~C~ 3~
This application is a division of application Serial No. 411,393, filed September 14, 1982.
Claims (3)
1. A method for manufacturing an endless belt for use in an extended press nip, comprising:
providing the endless base fabric;
coating and impregnating of polymeric resin by doctoring into the fabric and curing said resin to form a smooth surface.
providing the endless base fabric;
coating and impregnating of polymeric resin by doctoring into the fabric and curing said resin to form a smooth surface.
2. A method as defined in claim 1, including the step of trimming the edges of said base fabric after impregnating it with the polymeric material.
3. A method as defined in claim 1, wherein the so-formed resin surface is ground after the resin has been cured.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000470970A CA1205335A (en) | 1981-09-15 | 1984-12-21 | Method of manufacturing an endless resin impregnated belt |
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US30234581A | 1981-09-15 | 1981-09-15 | |
| US302,345 | 1981-09-15 | ||
| CA000411393A CA1188556A (en) | 1981-09-15 | 1982-09-14 | Dewatering press |
| CA000470970A CA1205335A (en) | 1981-09-15 | 1984-12-21 | Method of manufacturing an endless resin impregnated belt |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000411393A Division CA1188556A (en) | 1981-09-15 | 1982-09-14 | Dewatering press |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1205335A true CA1205335A (en) | 1986-06-03 |
Family
ID=25669810
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000470970A Expired CA1205335A (en) | 1981-09-15 | 1984-12-21 | Method of manufacturing an endless resin impregnated belt |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1205335A (en) |
-
1984
- 1984-12-21 CA CA000470970A patent/CA1205335A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5238537A (en) | Extended nip press belt having an interwoven base fabric and an impervious impregnant | |
| CA1188556A (en) | Dewatering press | |
| CA1190779A (en) | Dewatering press | |
| CA2061804C (en) | Reinforcement of coated surfaces of lnp belts | |
| EP0761873B1 (en) | Spiral base structures for long nip paper machine press belts | |
| EP0541498B1 (en) | Spiral construction of grooved, void-volume LNP belts | |
| CA2395748C (en) | Grooved long nip shoe press belt | |
| US6419795B1 (en) | Resin-impregnated belt having a texturized outer surface for application on papermaking machines | |
| US5234551A (en) | Extended nip press belt having an interwoven base fabric and an impervious impregnant | |
| US7384516B2 (en) | Belt with variable grooves | |
| EP0194602B1 (en) | A method for producing an endless belt with a smooth inner surface for use in a papermaking extended nip press | |
| US7011730B2 (en) | Structure for process belt | |
| CA1205335A (en) | Method of manufacturing an endless resin impregnated belt | |
| EP1005589B1 (en) | Resin-impregnated belt having a texturized outer surface for application on papermaking machines | |
| CA1201883A (en) | Manufacture of endless belts for use in extended nip press |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |