Gel reduction device and gel reduction method

Abstract

A gel reduction device 1 of the present invention includes a gel reduction mechanism 8 provided in a polymer flow duct 5 in which a polymer kneaded compound flows and adapted to reduce gel present in the polymer kneaded compound. The gel reduction mechanism 8 includes at least one or more squeezing flow paths 10 having a flow path cross-sectional area smaller than the polymer flow duct 5 , and a squeeze ratio S 1 /S 2 of the squeezing flow paths 10 is set to be 25 to 180 so as to be able to generate an extensional flow in the kneaded compound flowing in the squeezing flow paths 10.

1 . A gel reduction device, comprising:
 a gel reduction mechanism provided in a polymer flow duct in which a polymer kneaded compound flows and adapted to reduce gel present in the polymer kneaded compound,   the gel reduction mechanism includes at least one or more squeezing flow paths having a flow path cross-sectional area smaller than the polymer flow duct, and   a squeeze ratio S 1 /S 2  of the squeezing flow path is set to satisfy the following relationship to generate an extensional flow in the kneaded compound flowing in the squeezing flow path:
   squeeze ratio  S 1 /S 2 of the squeezing flow path=25 to 180 
   
       where S 1 : flow path cross-sectional area of the polymer flow duct and S 2 : sum total of flow path cross-sectional area of the squeezing flow path. 
     
     
         2 . A gel reduction device according to  claim 1 , wherein:
 the gel reduction mechanism includes a plate-like member provided to cross the polymer flow duct; and   the squeezing flow path is a circular through hole provided in the plate-like member.   
     
     
         3 . A gel reduction device according to  claim 1 , wherein the gel reduction mechanism includes a plurality of gel reduction members arranged while being spaced apart from each other in a laying direction of the polymer flow duct. 
     
     
         4 . A gel reduction device according to  claim 3 , wherein:
 a squeezing flow path of the gel reduction member provided at an upstream side of the polymer flow duct and that of the gel reduction member provided at a downstream side do not overlap when viewed in the laying direction of the polymer flow duct.   
     
     
         5 . A gel reduction device according to  claim 1 , wherein:
 the gel reduction mechanism includes a filter-like member provided to cross the polymer flow duct; and   the squeezing flow path is a circular through hole provided in the filter-like member.   
     
     
         6 . A gel reduction device according to  claim 5 , wherein a mesh size of the filter-like member is set to 180 μm or finer. 
     
     
         7 . A gel reduction device according to  claim 5 , wherein the gel reduction mechanism has a multilayer structure including the filter-like member and supporting mesh members sandwiching the filter-like member from upstream and downstream sides and having a mesh size coarser than the filter-like member. 
     
     
         8 . A gel reduction device according to  claim 7 , wherein the supporting mesh members are formed with openings having the same flow path cross-sectional area as the squeezing flow path of the filter-like member and communicating with the squeezing flow path. 
     
     
         9 . A gel reduction device according to any one of  claims 5  to  8 , wherein a supporting member for supporting the filter-like member from the downstream side is provided at the downstream side of the gel reduction mechanism; and
 said supporting member is formed with a flow hole which allows the polymer kneaded compound having passed through the gel reduction mechanism to be further fed toward the downstream side. 
 
     
     
         10 . A gel reduction device according to  claim 9 , wherein:
 the flow hole formed in the supporting member communicates with the squeezing flow path formed in the gel reduction mechanism when viewed in the laying direction of the polymer flow duct; and   the sum total of the flow path cross-sectional area of the flow hole formed in the supporting member is equal to or larger than the sum total of the flow path cross-sectional area of the squeezing flow path formed in the gel reduction mechanism.   
     
     
         11 . A method for reducing gel present in a polymer kneaded compound flowing in a polymer flow duct, comprising:
 a step of providing a gel reduction mechanism including at least one or more squeezing flow paths having a flow path cross-sectional area smaller than the polymer flow duct in the polymer flow duct,   wherein a squeeze ratio S 1 /S 2  of the squeezing flow path is set to satisfy the following relationship to generate an extensional flow in the kneaded compound flowing in the squeezing flow path:
   squeeze ratio  S 1 /S 2 of the squeezing flow path=25 to 180 
   where   S 1  is a flow path cross-sectional area of the polymer flow duct and   S 2  is a sum total of flow path cross-sectional area of the squeezing flow path; and   a step of introducing the polymer kneaded compound to the squeezing flow path.   
     
     
         12 . A method for reducing gel present in a polymer kneaded compound flowing in a polymer flow duct, comprising:
 a step of constantly applying a pressure drop of 8.8 MPaG or higher to a kneaded polymer containing gel at an intermediate position of the polymer flow duct in which the resin flows, thereby reducing the gel in the resin.   
     
     
         13 . A method for reducing gel present in a polymer kneaded compound flowing in a polymer flow duct, comprising:
 a step of providing a pressure drop adding device for producing a predetermined pressure drop in a kneaded polymer containing gel at an intermediate position of the polymer flow duct in which the resin flows,   wherein a pressure drop of 8.8 MPaG or higher is constantly applied to the polymer by the pressure drop adding device to reduce the gel in the polymer   
     
     
         14 . A method according to  claim 12  or  13 , wherein the pressure drop to be applied to the polymer is 25.0 MPaG or lower. 
     
     
         15 . A method according to  claim 12  or  13 , wherein the resin is an HDPE having a melt index of 0.01 to 10 g/10 min when being heated to 190° C. with 2.16 Kg load. 
     
     
         16 . A gel reduction device for reducing gel present in a polymer kneaded compound flowing in a polymer flow duct, comprising:
 a pressure drop adding device for producing a predetermined pressure drop to a kneaded resin containing gel at an intermediate position of the polymer flow duct in which the resin is flowing,   wherein a pressure drop of 8.8 MPaG or higher is constantly applied to the resin by the pressure drop adding device to reduce the gel in the resin.   
     
     
         17 . A gel reduction device according to  claim 16 , wherein the pressure drop applied to the resin is 25.0 MPaG or lower.