To provide a method for producing a fluororesin film, whereby defects due to deterioration (such as fish-eyes due to gelation) of a melt-processable fluororesin are less likely to occur during the production. A method for producing a fluororesin film, which comprises extruding a fluororesin material containing a melt-processable fluororesin through an extruder die, wherein the temperature of the extruder die is from 305 to 355 C., and the average flow velocity v.sub.0.95 of the fluororesin material as obtained by v.sub.0.95=Q.sub.0.95/A.sub.0.95, is at least 110.sup.4 m/sec. Here, when the distance from the flow inlet 22 of the extruder die to the end of the manifold 24 of the extruder die is set to be x=1, Q.sub.0.95 is the flow rate (m.sup.3/sec) of the fluororesin material flowing in the manifold 24 at a position of x=0.95 from the flow inlet 22, and A.sub.0.95 is the cross-sectional area (m.sup.2) of the manifold 24 at a position of x=0.95 from the flow inlet 22.

A dimension in a Y-direction of a slit section (26) decreases gradually as a distance from an inflow port (23) in an X-direction increases. A cross-section of a manifold section (25) that is orthogonal to the X-direction decreases gradually as a distance from the inflow port (23) in the X-direction increases.

The invention relates to a melt conductor (1), in particular a melt distributor or melt mixer, for an extruding die (2) of an extrusion facility (3), comprising a melt conductor block (4) with a multi-channel system (5), the multi-channel system (5) being arranged inside the melt conductor block (4) with three-dimensional extension and having at least one input (6) and at least one output (7) for polymer melt, between one input (6) and one output (7) fluidically connected to the input (6) several branchings (8) arranged in series and several levels (9a) of sub-branches (10) being formed over several levels (12a, 12b) of divided melt channels (11a, 11b); with m melt channels (11a) of the a.sup.th level (12a) with X.sup.th local cross-sections and n melt channels (11b) of the b.sup.th level (12b) with y.sup.th local cross-sections being present, wherein n>m if b>a, the y.sup.th local cross-sections of the melt channels (11b) of the b.sup.th level (12b) being smaller than the X.sup.th local cross-sections of the melt channels (11a) of the a.sup.th level (12a). The invention further relates to an extruding die, an extrusion facility and to a method of operating the extrusion facility.

A method of forming a blown polymeric foam film is described herein. As described further below, equipment design (e.g., die design) and processing conditions may be controlled to form blown films having desired characteristics.

The invention relates to a melt conductor (1), in particular a melt distributor or melt mixer, for an extruding die (2) of an extrusion facility (3), comprising a melt conductor block (4) with a multi-channel system (5), the multi-channel system (5) being arranged inside the melt conductor block (4) with three-dimensional extension and having at least one input (6) and at least one output (7) for polymer melt, between one input (6) and one output (7) fluidically connected to the input (6) several branchings (8) arranged in series and several levels (9a) of sub-branches (10) being formed over several levels (12a, 12b) of divided melt channels (11a, 11b); with m melt channels (11a) of the a.sup.th level (12a) with X.sup.th local cross-sections and n melt channels (11b) of the b.sup.th level (12b) with y.sup.th local cross-sections being present, wherein n>m if b>a, the y.sup.th local cross-sections of the melt channels (11b) of the b.sup.th level (12b) being smaller than the X.sup.th local cross-sections of the melt channels (11a) of the a.sup.th level (12a). The invention further relates to an extruding die, an extrusion facility and to a method of operating the extrusion facility.

An apparatus for producing polymeric nanofibers utilizes a meltblown spinneret die having spin holes formed by grooves in plate(s) surface(s) of plate(s) where polymer exits at the plate(s) edge(s). The grooves are smaller than 0.005 wide0.004 deep and have an L/D at least as large as 20:1. Flow rates of polymer through the apparatus are very low, on the order of 0.01 ghm or less. A meltblown fabric having fibers mostly less than 0.5 microns in diameter is produced.

To provide a method for producing a fluororesin film, whereby defects due to deterioration (such as fish-eyes due to gelation) of a melt-processable fluororesin are less likely to occur during the production. A method for producing a fluororesin film, which comprises extruding a fluororesin material containing a melt-processable fluororesin through an extruder die, wherein the temperature of the extruder die is from 305 to 355 C., and the average flow velocity v.sub.0.95 of the fluororesin material as obtained by v.sub.0.95=Q.sub.0.95/A.sub.0.95, is at least 110.sup.4 m/sec. Here, when the distance from the flow inlet 22 of the extruder die to the end of the manifold 24 of the extruder die is set to be x=1, Q.sub.0.95 is the flow rate (m.sup.3/sec) of the fluororesin material flowing in the manifold 24 at a position of x=0.95 from the flow inlet 22, and A.sub.0.95 is the cross-sectional area (m.sup.2) of the manifold 24 at a position of x=0.95 from the flow inlet 22.

A dimension in a Y-direction of a slit section (26) decreases gradually as a distance from an inflow port (23) in an X-direction increases. A cross-section of a manifold section (25) that is orthogonal to the X-direction decreases gradually as a distance from the inflow port (23) in the X-direction increases.

A die for forming a honeycomb structure, including: a second plate-shaped portion that is formed of iron and the like and has back holes; and a first plate-shaped portion that is formed of tungsten carbide based cemented carbide and has cavities communicating with the back holes and slits communicating with the cavities, with the first plate-shaped portion having a first layer arranged in the second plate-shaped portion side and a second layer arranged on the first layer, the cavities are opened on both sides of the first layer, and the slits are opened on both sides of the second layer.