Press jacket and use thereof, and press roll and shoe press

Abstract

A press cover or jacket includes at least a first and a second polymer layer. The first polymer layer is a radially outermost polymer layer as seen relative to the longitudinal axis of the press cover and has a thickness that is at most 60% of the overall thickness of the press cover as seen in the radial direction of the press cover. The first polymer layer includes grooves or holes which are incorporated in the radially outermost lateral surface thereof and the depth of the grooves or holes, as seen in the radial direction of the press cover, have a depth that corresponds at most to 95% of the thickness of the first polymer layer. A press roll, a shoe press and a method of using a press cover are also provided.

1 - 14 . (canceled) 
     
     
         15 . A press cover ( 20 ), band, hose or jacket to be guided together with a fibrous material web through a press nip of a shoe press, the press cover comprising:
 a first polymer layer ( 20 . 1 ) being a radially outermost polymer layer of the press cover ( 20 ) relative to a longitudinal axis ( 20 ′) of the press cover ( 20 ), said first polymer layer ( 20 . 1 ) having a thickness of not more than 60% of a total thickness of the press cover ( 20 ) in a radial direction of the press cover ( 20 ), said first polymer layer ( 20 . 1 ) having a radially outermost shell surface and grooves or holes introduced into said radially outermost shell surface, said grooves or holes having a depth in the radial direction of the press cover ( 20 ) of at most 95% of a thickness of said first polymer layer ( 20 . 1 );   a second polymer layer ( 20 . 2 ) being a radially innermost polymer layer relative to the longitudinal axis ( 20 ′) of the press cover ( 20 );   said first and second polymer layers ( 20 . 1 ,  20 . 2 ) each including or being formed from a polyurethane, and said polyurethane being formed from a prepolymer and a crosslinker;   said prepolymer of said first polymer layer ( 20 . 1 ) being a reaction product of:
 phenylene 1,4-diisocyanate (PPDI), naphthalene 1,5-diisocyanate (NDI) or 3,3′-dimethyl-4,4′-biphenylene diisocyanate (TODI) and at least one polyol selected from a polyether polyol, a polycarbonate polyol, a polyether polycarbonate polyol, or 
 diphenylmethane 4,4′-diisocyanate (MDI) and at least one polyol selected from a polycarbonate polyol, a polyether polycarbonate polyol, or 
 mixtures thereof; 
   said prepolymer of said second polymer layer ( 20 . 2 ) being a reaction product of:
 diphenylmethane 4,4′-diisocyanate (MDI), toluene 2,4-diisocyanate (TDI) or naphthalene 1,5-diisocyanate (NDI) and at least one polyol selected from a polyether polyol, or 
 mixtures thereof; and 
   said crosslinker including butane-1,4-diol (BDO), hydroquinone 1,4-bis(2-hydroxyethyl) ether (HQEE), 4,4′-methylenebis(3-chloro-2,6-diethylaniline) (MCDEA), diethyltoluenediamine (DETDA), dimethylthiotoluenediamine (DMTDA) or mixtures thereof.   
     
     
         16 . The press cover ( 20 ) according to  claim 15 , wherein said thickness of said first polymer layer ( 20 . 1 ) corresponds to at least 5% of the total thickness of the press cover ( 20 ). 
     
     
         17 . The press cover ( 20 ) according to  claim 15 , wherein said thickness of said first polymer layer ( 20 . 1 ) corresponds to at most 55% of the total thickness of the press cover ( 20 ). 
     
     
         18 . The press cover ( 20 ) according to  claim 15 , wherein said depth of said grooves or holes corresponds to at least 35% of said thickness of said first polymer layer ( 20 . 1 ). 
     
     
         19 . The press cover ( 20 ) according to  claim 15 , wherein said depth of said grooves or holes corresponds to at least 50% of said thickness of said first polymer layer ( 20 . 1 ). 
     
     
         20 . The press cover ( 20 ) according to  claim 15 , wherein said first and second polymer layers ( 20 . 1 ,  20 . 2 ) adjoin one another in the radial direction of the press cover ( 20 ). 
     
     
         21 . The press cover ( 20 ) according to  claim 15 , wherein said first polymer layer ( 20 . 1 ) has a Shore A hardness of between 90 and 98. 
     
     
         22 . The press cover ( 20 ) according to  claim 15 , wherein said second polymer layer ( 20 . 2 ) has a Shore A hardness of between 90 and 96. 
     
     
         23 . The press cover ( 20 ) according to  claim 15 , wherein said first and second polymer layers ( 20 . 1 ,  20 . 2 ) have a Shore A hardness differing by between 1 and 6, and said second polymer layer ( 20 . 2 ) is less hard than said first polymer layer ( 20 . 1 ). 
     
     
         24 . A press roll or shoe press roll ( 12 ) for a shoe press ( 10 ) for treatment of a fibrous material web ( 24 ), the press roll or shoe press roll ( 12 ) comprising at least one press cover ( 20 ) according to  claim 15 . 
     
     
         25 . A shoe press ( 10 ) for treatment of a fibrous material web ( 24 ), a paper web, a cardboard web, a tissue web or a pulp web, the shoe press ( 10 ) comprising:
 a press roll or shoe press roll ( 12 ) and an opposing roll ( 14 ) together forming or bounding a nip ( 22 );   said press roll or shoe press roll ( 12 ) including a circumferential press cover according to  claim 15 .   
     
     
         26 . A method of using a press cover ( 20 ) for a press or shoe press ( 10 ), the method comprising the following steps:
 treating a fibrous material web ( 24 ), a paper web, a cardboard web, a tissue web or a pulp web by using the press cover ( 20 ) according to  claim 15 .