Solidification- and extrusion-molded article of polyglycolic acid and method for manufacturing same

Abstract

A solidification- and extrusion-molded article of polyglycolic acid, which is formed of a resin material containing polyglycolic acid, the polyglycolic acid having a melt viscosity of 200 to 2,000 Pa·s, and has a thickness or diameter of greater than 100 mm but not greater than 500 mm. A downhole tool or a component thereof and a ball sealer for petroleum excavation are formed by cutting the solidification- and extrusion-molded article. A method for manufacturing the solidification- and extrusion-molded article of polyglycolic acid and a method for manufacturing a ball sealer for petroleum excavation.

1 . A solidification- and extrusion-molded article of polyglycolic acid; the solidification- and extrusion-molded article being formed of a resin material containing polyglycolic acid, the polyglycolic acid having a melt viscosity of 200 to 2,000 Pa·s upon being measured at a temperature of 270° C. under a shearing speed of 120 sec−1; and having a thickness or diameter of greater than 100 mm but not greater than 500 mm. 
     
     
         2 . The solidification- and extrusion-molded article of polyglycolic acid according to  claim 1 , wherein the solidification- and extrusion-molded article has a round bar or plate shape. 
     
     
         3 . The solidification- and extrusion-molded article of polyglycolic acid according to  claim 1 , wherein the resin material is a polyglycolic acid composition containing from 0.001 to 5 mass % of colorant in terms of a total mass. 
     
     
         4 . The solidification- and extrusion-molded article of polyglycolic acid according to  claim 1 , wherein the resin material is a polyglycolic acid composition containing from 5 to 70 mass % of filler in terms of the total mass. 
     
     
         5 . The solidification- and extrusion-molded article of polyglycolic acid according to  claim 1 , wherein the solidification- and extrusion-molded article is a stock shape for machining. 
     
     
         6 . A downhole tool or component thereof formed by cutting the solidification- and extrusion-molded article of polyglycolic acid described in  claim 5 . 
     
     
         7 . A plug for petroleum excavation formed by cutting the solidification- and extrusion-molded article of polyglycolic acid described in  claim 5 . 
     
     
         8 . A mandrel of plug for petroleum excavation formed by cutting the solidification- and extrusion-molded article of polyglycolic acid described in  claim 5 . 
     
     
         9 . A ball sealer for petroleum excavation having a diameter of 20 to 200 mm formed by cutting the solidification- and extrusion-molded article of polyglycolic acid described in  claim 5 . 
     
     
         10 . A method for manufacturing a solidification- and extrusion-molded article of polyglycolic acid, the method comprising steps 1 to 4 below:
 a) step 1 of supplying a resin material containing polyglycolic acid, the polyglycolic acid having a melt viscosity of 200 to 2,000 Pa·s upon being measured at a temperature of 270° C. under a shearing speed of 120 sec −1 , into an extruder, and melt-kneading the resin material at a cylinder temperature of the extruder of 240 to 285° C.;   b) step 2 of extruding the resin material, melted by the melt-kneading, from an extrusion die at a tip of the extruder into a flow path of a forming die comprising cooling means and the flow path that communicates with a path of melted resin of the extrusion die and that has a cross-sectional shape of an extrusion molded article;   c) step 3 of solidifying the melted and extruded matter formed from the resin material by cooling in the flow path of the forming die, and then extruding the solidified and extruded matter from the tip of the forming die to outside; and   d) step 4 of pressurizing the solidified and extruded matter, and drawing the same while applying back pressure thereto in a direction of the forming die to suppress expansion of the solidified and extruded matter in a thickness direction or radial direction to obtain a solidification- and extrusion-molded article of polyglycolic acid having a thickness or diameter of greater than 100 mm but not greater than 500 mm.   
     
     
         11 . The manufacturing method according to  claim 10 , wherein, in the step 3, a forming die having heating means in addition to the cooling means is used; and the step 3 comprises: first, heating the melted and extruded matter in the flow path around an extrusion die outlet to a temperature of 230 to 290° C. by the heating means, and then cooling the melted and extruded matter in the flow path to a temperature lower than a crystallization temperature of the polyglycolic acid to solidify the melted and extruded matter by the cooling means. 
     
     
         12 . The manufacturing method according to  claim 10 , further comprising step 5, in which the solidification- and extrusion-molded article of polyglycolic acid obtained in the step 4 is heat-treated at a temperature of 150 to 230° C. for 3 to 24 hours. 
     
     
         13 . The manufacturing method according to  claim 10 , wherein the resin material is a polyglycolic acid composition containing from 0.001 to 5 mass % of colorant in terms of a total mass. 
     
     
         14 . The manufacturing method according to  claim 10 , wherein the resin material is a polyglycolic acid composition containing from 5 to 70 mass % of filler in terms of the total mass. 
     
     
         15 . The manufacturing method according to  claim 10 , wherein, in the step 4, a solidification- and extrusion-molded article of polyglycolic acid having a round bar or plate shape is obtained. 
     
     
         16 . A method for manufacturing a downhole tool or component thereof, the method comprising step  6  of cutting the solidification- and extrusion-molded article of polyglycolic acid manufactured by the manufacturing method described in  claim 10 . 
     
     
         17 . A method for manufacturing a ball sealer for petroleum excavation having a diameter of 20 to 200 mm, the method comprising step 6 of cutting the solidification- and extrusion-molded article of polyglycolic acid manufactured by the manufacturing method described in  claim 10 .