Provided is a process for producing a nonwoven fabric. The process includes extruding a plurality of filaments from a spinneret, the filaments being at least bicomponent filaments; depositing the filaments to form a nonwoven fabric on an element collecting the filaments; performing a bonding of the nonwoven fabric; increasing the thickness of the nonwoven fabric by crimping at least part of the filaments by heating the nonwoven fabric; and, preferably performing a setting of the nonwoven fabric, wherein the bonding and the increasing the thickness steps are performed substantially simultaneously by means of a heated calendar. Also provided is the nonwoven fabric formed using the process and an apparatus for carrying out the process.

Provided is a process for producing a nonwoven fabric. The process includes extruding a plurality of filaments from a spinneret, the filaments being at least bicomponent filaments; depositing the filaments to form a nonwoven fabric on an element collecting the filaments; performing a bonding of the nonwoven fabric; increasing the thickness of the nonwoven fabric by crimping at least part of the filaments by heating the nonwoven fabric; and, preferably performing a setting of the nonwoven fabric, wherein the bonding and the increasing the thickness steps are performed substantially simultaneously by means of a heated calendar. Also provided is the nonwoven fabric formed using the process and an apparatus for carrying out the process.

The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral-wound filter elements having cassette-like performance.

The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral-wound filter elements having cassette-like performance.

The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral-wound filter elements having cassette-like performance.

The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral-wound filter elements having cassette-like performance.

The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral-wound filter elements having cassette-like performance.

The present invention provides compact spiral-wound filter elements having cassette-like performance. The invention further provides filtration systems (e.g., TFF systems) and processes (e.g., SPTFF processes) employing compact spiral-wound filter elements having cassette-like performance.

Calender for treating web materials, comprising a structure for supporting two heated rollers forming a nip, wherein each roller has surface reliefs (RR) and in an operational setting of the calender the reliefs of one roller are radially opposed to those of the other roller, each roller rotates with a predetermined angular speed around its axis, the rollers are heated by heating means, and each roller undergoes an axial elongation as a consequence of its heating. The calender comprises detection means (E1, E2; IS) adapted to detect the axial elongation of each roller and a programmable control unit (UCP) connected to the detection means and to the heating means. The control unit is programmed to determine the difference between the axial elongations of the rollers and emitting an alarm signal if the absolute value of this difference is greater than a limit value.

Calender for treating web materials, comprising a structure for supporting two heated rollers forming a nip, wherein each roller has surface reliefs (RR) and in an operational setting of the calender the reliefs of one roller are radially opposed to those of the other roller, each roller rotates with a predetermined angular speed around its axis, the rollers are heated by heating means, and each roller undergoes an axial elongation as a consequence of its heating. The calender comprises detection means (E1, E2; IS) adapted to detect the axial elongation of each roller and a programmable control unit (UCP) connected to the detection means and to the heating means. The control unit is programmed to determine the difference between the axial elongations of the rollers and emitting an alarm signal if the absolute value of this difference is greater than a limit value.