Die for extrusion and method of designing die for extrusion

Patent metadata

Field	Value
Publication number	US-11660796-B2
Application number	US-202016918442-A
Country	US
Kind code	B2
Filing date	Jul 1, 2020
Priority date	Aug 9, 2019
Publication date	May 30, 2023
Grant date	May 30, 2023

Abstract

There is provided a die for extrusion in which an undesired reaction is suppressed in an inside thereof and with which variation in thickness of a resin sheet to be obtained can be reduced. A die for extrusion of the present invention includes: a cylindrical inflow port into which a molten resin flows; a manifold connected to the inflow port; a first slit connected to the manifold; a second slit connected to the first slit; and a lip land connected to the second slit. In the die for extrusion, the shape of a flow path is optimized based on a relationship among a position in the die, an operation time, and a vulcanization degree.

First claim

What is claimed is:

1. A die for extrusion, comprising:
a cylindrical inflow port into which a molten resin flows;
a manifold connected to the inflow port;
a first slit connected to the manifold;
a second slit connected to the first slit; and
a lip land connected to the second slit,
wherein: when seen in plan view on each of an upper part and a lower part of the first slit, the manifold has a substantially inverted V-shape in which an apex is flattened at a connected portion to the inflow port, and which extends in a width direction toward a downstream direction with a center portion of the inflow port at the connected portion as an apex angle portion; portions forming the V-shape are each reduced in thickness and width from the connected portion to the inflow port toward the downstream direction; and the apex angle portion of the V-shape is configured so that the inflow port extends in a tapered shape to the first slit while being reduced in thickness toward the downstream direction,
wherein, when seen in plan view, the first slit is defined, by the manifold, as a pentagon shape in which an isosceles triangle and a rectangle are combined with each other,
wherein the second slit includes: a flat portion defined as a center portion in a flow direction; a first tapered portion connected to the first slit and reduced in thickness from a thickness of the first slit to a thickness of the flat portion; and a second tapered portion connected to the lip land and increased in thickness from the thickness of the flat portion to a thickness of the lip land,
wherein, with respect to a diameter of the inflow port, a ratio of an extended length of the apex angle portion of the V-shape is 1.45 or less, a ratio of a thickness of the second slit is 0.04 or less, and a ratio of a length of the lip land is 0.92 or more, and
wherein a taper angle α of the apex angle portion of the V-shape is 38° or more, and an apex angle of the isosceles triangle of the first slit is 110° or less.

2. The die for extrusion according to claim 1 ,
wherein the molten resin comprises a vulcanizing agent, and
wherein the molten resin has a maximum vulcanization degree of 76.8% or less in the die at a time of continuous operation for 144 hours.

3. The die for extrusion according to claim 1 , wherein a difference between a maximum value and a minimum value of a thickness of a resin sheet to be obtained in the width direction is 20% or less of a preset thickness.

Assignees

• Nitto Denko Corp

Inventors

• Kono Yoshinori
• Kido Akifumi
• AZUKIZAWA Makoto

Classifications

• B29C48/08

  flexible, e.g. films · CPC title

• B29K2023/16

  EPM, i.e. ethylene-propylene copolymers; EPDM, i.e. ethylene-propylene-diene copolymers; EPT, i.e. ethylene-propylene terpolymers · CPC title

• B29C48/3001

  characterised by the material or their manufacturing process · CPC title

• B29C48/305 Primary

  having a wide opening, e.g. for forming sheets · CPC title

• B29K2105/24

  crosslinked or vulcanised · CPC title