Dryer fabric for a condensation drying apparatus

Abstract

A dryer fabric for a condensation drying apparatus in a machine which produces and/or processes a web material, such as paper, cardboard or tissue, includes a base structure which essentially provides the dimensional stability of the fabric and which consists of polyester and/or PCTA and/or PCT and/or PEEK and/or PPS and/or thread material which includes PA with high temperature stability; a fibrous nonwoven layer located on the basic structure, which essentially provides the water absorption capacity of the fabric and which provides the dryer fabric with a web material contact side on its outside, facing away from the basic structure, whereby the fibrous nonwovens layer comprises a first polymer material located at least in the area of the outside and whereby the fibrous nonwovens layer is compressed and smoothed in the area of the outside which provides the web material contact side through means of hot-calendering above the melting temperature of the first polymer material.

1 . A dryer fabric for a condensation drying apparatus in a machine for at least one of producing and processing a fibrous web material, comprising:
 a base structure which essentially provides the dimensional stability of the fabric and which consists essentially of at least one of polyester and PCTA and PCT and PEEK and PPS and thread material which includes PA with high temperature stability; and   a fibrous nonwoven layer located on the base structure, which essentially provides the water absorption capacity of the fabric and which provides the dryer fabric with a web material contact side on its outside, facing away from the base structure, whereby the fibrous nonwovens layer includes a first polymer material located at least in the area of the outside and whereby the fibrous nonwovens layer is compressed and smoothed in the area of the outside which provides the web material contact side by way of hot-calendering above the melting temperature of the first polymer material.   
   
   
       2 . The dryer fabric according to  claim 1 , wherein the fibrous nonwoven layer is formed by the first polymer material. 
   
   
       3 . The dryer fabric according to  claim 1 , wherein the fibrous nonwoven layer is formed by the first polymer material and at least a second polymer material with a higher melting temperature than the first polymer material and that in the area of the outside which represents the web material contact side, the nonwoven fibrous layer is compressed and smoothed through hot-calendering above the melting temperature of the first polymer material and below the melting temperature of the at least one second polymer material. 
   
   
       4 . The dryer fabric according to  claim 3 , wherein the second polymer material is present in the form of fibers in the fibrous nonwovens layer, and the first polymer material prior to its being melted is located between the fibrous material in the form of particles. 
   
   
       5 . The dryer fabric according to  claim 3 , wherein the fibrous nonwoven layer includes Bi-component fibers or consists of these, whereby prior to hot-calendering the first polymer material exists as one component and the second polymer material as second component of the BI-component fibers. 
   
   
       6 . The dryer fabric according to  claim 1 , wherein the first polymer is a thermoplast. 
   
   
       7 . The dryer fabric according to  claim 6 , wherein the first polymer is a co-polyamide. 
   
   
       8 . The dryer fabric according to  claim 3 , wherein the second polymer is a thermoplast. 
   
   
       9 . The dryer fabric according to  claim 8 , wherein the second polymer is a polyamide. 
   
   
       10 . The dryer fabric according to  claim 1 , wherein the outside is passed over a heated smooth surface during the hot-calendering. 
   
   
       11 . The dryer fabric according to  claim 1 , wherein during cooling from a temperature above the melting temperature to a temperature below the melting temperature of the first polymer material, the outside is carried under pressure over a smooth surface. 
   
   
       12 . The dryer fabric according to  claim 1 , wherein the first polymer material has a melting temperature of at least 110° C. 
   
   
       13 . The dryer fabric according to  claim 1 , wherein the porosity of the material layer increases from the outside which provides the web material contact side in the direction of the base structure. 
   
   
       14 . The dryer fabric according to  claim 1 , wherein the base structure includes one of a woven structure, a laid thread structure, and a knitted fabric structure. 
   
   
       15 . The dryer fabric according to  claim 1 , wherein the dryer fabric has a water absorption capacity of 100-150 kg per hour per m 2 . 
   
   
       16 . The dryer fabric according to  claim 1 , wherein the dryer fabric is water permeable and water vapor permeable and has a permeability of between approximately 1 to 200 cfm. 
   
   
       17 . The dryer fabric according to  claim 16 , wherein the dryer fabric has a permeability of between approximately 10 to 95 cfm. 
   
   
       18 . The dryer fabric according to  claim 1 , wherein the outside of the dryer fabric which provides the web material contact side has a coarseness RZ of between approximately 0.6 μm to 6 μm according to DIN EN ISO 4287, DIN EN ISO 4288. 
   
   
       19 . The dryer fabric according to  claim 1 , wherein between the fibrous nonwoven layer which provides the web material contact side and the base structure, at least one fibrous nonwoven layer is arranged whose fibers are of a polymer material which has a higher melting temperature than the first polymer material. 
   
   
       20 . The dryer fabric according to  claim 1 , wherein on the side of the base structure facing away from the web material contact side at least one fibrous nonwoven layer is arranged whose fiber forming polymer material has a higher melting temperature than the first polymer material and whose other outside which faces away from the base structure provides a machine contact side of the dryer fabric. 
   
   
       21 . A machine for at least one of producing and processing a fibrous web material, comprising:
 a condensation drying apparatus with at least one heatable drying cylinder whose surface area in an area of contact is wrapped by the web material, at least one dryer fabric, and a water and steam impermeable sealing belt, and   a cooling medium whose temperature is lower than the temperature of the surface area of the drying cylinder, whereby in the area of contact one side of the fibrous web material is in contact with the surface area of the drying cylinder and the other side of the web material is in contact with the web material contact side of the dryer fabric, while the machine contact side of the dryer fabric is in contact with one side of the sealing belt whose other side is treated with the cooling medium.   
   
   
       22 . The machine according to  claim 21 , wherein said at least one dryer fabric includes:
 a base structure which essentially provides the dimensional stability of the fabric and which consists essentially of at least one of polyester and PCTA and PCT and PEEK and PPS and thread material which includes PA with high temperature stability; and   a fibrous nonwoven layer located on the base structure, which essentially provides the water absorption capacity of the fabric and which provides the dryer fabric with a web material contact side on its outside, facing away from the base structure, whereby the fibrous nonwovens layer includes a first polymer material located at least in the area of the outside and whereby the fibrous nonwovens layer is compressed and smoothed in the area of the outside which provides the web material contact side by way of hot-calendering above the melting temperature of the first polymer material.   
   
   
       23 . The machine according to  claim 21 , wherein a pressure hood which is open toward the sealing belt is located over the sealing belt which, in interaction with the sealing belt provides an enclosed chamber in which the especially pressurized cooling medium is located. 
   
   
       24 . The machine according to  claim 21 , wherein the pressurized cooling medium exerts pressure upon the web material. 
   
   
       25 . The machine according to  claim 21 , wherein the cooling medium is one of a liquid and a gas. 
   
   
       26 . The machine according to  claim 21 , wherein the web material runs into the condensation drying apparatus at a dry content in the range of 50-80%. 
   
   
       27 . The machine according to  claim 21 , wherein the condensation drying apparatus viewed in direction of web travel is located after the press section, whereby the web material is fed into the condensation drying apparatus at a dry content of approx. 50-60%. 
   
   
       28 . The machine according to  claim 27 , wherein the condensation drying apparatus viewed in a direction of web travel is located after a first conventional dryer group of a drying section, whereby the web material is fed into the condensation drying apparatus at a dry content of approx. 70-80%. 
   
   
       29 . The machine according to  claim 21 , wherein the condensation drying apparatus viewed in a direction of web travel includes:
 a second heatable drying cylinder located after the first heatable drying cylinder whose surface in a contact area is wrapped by the web material, a second dryer fabric and a second water and steam impermeable sealing belt; and   a cooling medium whose temperature is less than the temperature of the surface area of the second drying cylinder, whereby in the contact area the other side of the web material is in contact with the surface area of the second drying cylinder and the one side of the web material is in contact with one of the web material contact side of the second dryer fabric and one side of the drying wire, while the machine contact side of the second dryer fabric is in contact with one side of the second sealing belt whose other side is treated with the cooling medium.   
   
   
       30 . The machine according to  claim 29 , wherein said second dryer fabric includes:
 a base structure which essentially provides the dimensional stability of the fabric and which consists essentially of at least one of polyester and PCTA and PCT and PEEK and PPS and thread material which includes PA with high temperature stability; and   a fibrous nonwoven layer located on the base structure, which essentially provides the water absorption capacity of the fabric and which provides the dryer fabric with a web material contact side on its outside, facing away from the base structure, whereby the fibrous nonwovens layer includes a first polymer material located at least in the area of the outside and whereby the fibrous nonwovens layer is compressed and smoothed in the area of the outside which provides the web material contact side by way of hot-calendering above the melting temperature of the first polymer material.   
   
   
       31 . The machine according to  claim 21 , wherein the sealing belt is a metal belt. 
   
   
       32 . The machine according to  claim 21 , wherein the web material is a graphic paper. 
   
   
       33 . The machine according to  claim 21 , wherein the web material is one of a copy paper and newsprint. 
   
   
       34 . The machine according to  claim 21 , wherein the web material is dried and glazed in the condensation drying apparatus.