Method of using a vented mold

Abstract

A novel method of molding an article includes providing a mold with a vent of a pre-determined size such that, due to the difference in viscosities, gases to be vented from the mold may easily pass through the vent while the material to be molded cannot quickly pass through the vent. In fact, the vent is designed such that the material to be molded which enters the vent, does not exit the end of the vent. In the most preferred embodiment, the vent is in the form of a thin ribbon-like groove so that the material to be molded which does enter the vent forms a thin ribbon of extruded material which need not be removed prior to a finish cover being applied to the molded article.

What is claimed is: 
     
       1. A method of producing an article in a mold comprising an upper mold and a lower mold defining a mold cavity, the process comprising the steps of: dispensing a liquid foamable polymeric composition into the mold cavity;   allowing the liquid foamable polymeric composition to expand to substantially fill the mold cavity;   venting gases in the mold cavity through at least one vent in the mold to allow the gases to exit from the mold, the vent comprising a passageway between an interior of the mold and an exterior of the mold;   selecting the size of each vent such that movement of the liquid foamable polymeric composition in the vent is restricted;   at least partially curing the liquid foamable polymeric composition in the vent, slowing the movement of the composition therein;   preventing the liquid foamable polymeric composition from exiting from the vent; and   wherein the size of each vent is also selected such that the at least partially cured polymeric composition, which is extruded into said vent passageway; (i) does not exit the vent passageway to the exterior of the mold, and (ii) is a ribbon of foam material which, when folded back against said article, may be covered with a cover material to produce a covered article of acceptable appearance and texture without the need to remove said ribbon from said article.   
     
     
       2. The method of claim 1 wherein said at least one vent is located at the part-line between said upper mold and said lower mold. 
     
     
       3. The method of claim 2 wherein the size of each vent comprises a thickness of from about 0.002 inches to about 0.030 inches. 
     
     
       4. The method of claim 2 wherein the size of each vent comprises a thickness of from about 0.005 inches to about 0.020 inches. 
     
     
       5. The method of claim 1, further comprising the step of venting gases from the mold cavity through a differential vent having a thickness of less than about 0.002 of an inch to inhibit substantially entry of said liquid foamable polymeric composition into said vent. 
     
     
       6. The method of claim 2 wherein each vent is substantially rectangular in cross-section and said liquid foamable polymeric composition entering said vent results in a ribbon of polymeric material attached to said article. 
     
     
       7. The method of claim 6 further comprising the steps of folding back said ribbon of polymeric material against said article and applying a finish cover to said article so that said ribbon is folded flat between said article and said finish cover. 
     
     
       8. The method of claim 3 wherein each vent is substantially rectangular in cross-section and said liquid foamable polymeric composition entering said vent results in a ribbon of polymeric material attached to said article. 
     
     
       9. The method of claim 8 further comprising the steps of folding back said ribbon of polymeric material against said article and applying a finish cover to said article so that said ribbon is folded flat between said article and said finish cover. 
     
     
       10. A method according to claim 1, wherein said selecting step includes the step of selecting a plurality of substantially rectangular cross-shaped vents, and wherein said liquid foamable polymeric composition forms a plurality of ribbons of polymeric material attached to said article. 
     
     
       11. A method of producing an article in a mold comprising an upper mold and a lower mold defining a mold cavity, the process comprising the steps of: dispensing a liquid foamable polymeric composition into the mold cavity;   allowing the liquid foamable polymeric composition to expand to substantially fill the mold cavity;   venting gases in the mold cavity through at least one vent in the mold to allow the gases to .[.exist.]. .Iadd.exit .Iaddend.from the mold, the size of each vent being selected such that movement of the liquid foamable polymeric composition into the vent is restricted to substantially prevent .[.exist.]. .Iadd.exit .Iaddend.thereof from the vent, said liquid foamable polymeric material entering into said vent forming a ribbon of polymeric material attached to said article; and   folding back said ribbon of polymeric material against said article and applying a finish cover to said article so that said ribbon is folded flat between said article and said finish cover.   
     
     
       12. A method of producing an article in a mold comprising an upper mold and a lower mold defining a mold cavity, the process comprising the steps of: dispensing a liquid foamable polymeric composition into the mold cavity;   allowing the liquid foamable polymeric composition to expand to substantially fill the mold cavity;   venting gases in the mold cavity through at least one vent in the mold to allow gases to exit from the mold; and   selecting the size of said at least one vent such that movement of the liquid foamable polymeric composition in the vent is restricted, and such that said vent extends between an interior of the mold an exterior of the mold;   at least partially curing the liquid foamable polymeric composition in the vent, slowing the movement of the composition therein;   causing the liquid foamable polymeric composition to enter the vent and preventing the liquid foamable polymeric composition from exiting from the vent to the exterior of the mold,   wherein the size of each vent is also selected (i) such that the at least partially cured polymeric composition, which is extruded into said vent, does not exit from the vent to the exterior of the mold, and (ii) such that the polymeric composition which cures within said vent forms a flexible extrusion capable of being folded back against said article when a finished cover is applied over both said article and said folded-back flexible extrusion, such that a covered article may be produced without the necessity of removing said flexible extrusion from said article.   
     
     
       13. The method of claim 12, wherein said at least one vent is located at the part-line between said upper mold and said lower mold. 
     
     
       14. The method of claim 13, wherein the size of each vent comprises a thickness of from about 0.002 inches to about 0.030 inches. 
     
     
       15. The method of claim 13, wherein the size of each vent comprises a thickness of from about 0.005 inches to about 0.020 inches. 
     
     
       16. The method of claim 12, further comprising the step of venting gases from the mold cavity through a differential vent having a thickness of less than about 0.002 of an inch to inhibit substantially entry of said liquid foamable polymeric composition into said vent. 
     
     
       17. The method of claim 13, wherein each vent is substantially rectangular in cross-section and said liquid foamable polymeric composition entering said vent results in a ribbon of polymeric material attached to said article. 
     
     
       18. The method of claim 17, further comprising the steps of folding back said ribbon of polymeric material against said article and applying a finish cover to said article so that said ribbon is folded flat between said article and said finish cover. 
     
     
       19. The method of claim 14, wherein each vent is substantially rectangular in cross-section and said liquid foamable polymeric composition entering said vent results in a ribbon of polymeric material attached to said article. 
     
     
       20. The method of claim 19, further comprising the steps of folding back said ribbon of polymeric material against said article and applying a finished cover to said article so that said ribbon is folded flat between said article and said finish cover. 
     
     
       21. .[.A.]. .Iadd.The .Iaddend.method of .[.producing an article in a mold comprising an upper mold and a lower mold defining a mold cavity, the process.]. .Iadd.claim 12, further .Iaddend.comprising the steps of: .[.dispensing a liquid foamable polymeric composition into the mold cavity;   allowing the liquid foamable polymeric composition to expand to substantially fill the mold cavity;   venting gases in the mold cavity through at least one vent in the mold to allow gases to exit from the mold;.].   .[.selecting.]. .Iadd.providing .Iaddend.a .Iadd.further .Iaddend.vent .Iadd.in said mold cavity, said further vent .Iaddend.having a passageway and an obstruction in said passageway, said obstruction and said passageway combining to form an opening having a shape which causes movement of the liquid foamable polymeric composition in the .Iadd.further .Iaddend.vent to be restricted, said vent passageway extending between an interior of the mold and an exterior of the mold;   at least partially curing the liquid foamable polymeric composition in the .Iadd.further .Iaddend.vent, slowing the movement of the composition therein;   preventing the liquid foamable polymeric composition from exiting from the .Iadd.further .Iaddend.vent,   wherein the size of .[.each.]. .Iadd.said further vent .Iaddend.is .[.also.]. selected such that the at least partially cured polymeric composition, which is extruded into said vent passageway .Iadd.of said further vent.Iaddend., does not exit from the vent passageway to the exterior of the mold; and   moving said obstruction axially inside said .Iadd.vent .Iaddend.passageway .Iadd.of said further vent .Iaddend.to expel the at least partially cured liquid foamable polymeric composition from the vent passageway.   
     
     
       22. The method of claim 21 wherein said .[.at least one.]. .Iadd.further .Iaddend.vent is located in said upper mold. 
     
     
       23. The method of claim 22 wherein .[.each.]. .Iadd.said further .Iaddend.vent is segmental in cross section. 
     
     
       24. The method of claim 22 wherein the size of .[.each.]. .Iadd.said further .Iaddend.vent comprises a thickness of from about 0.002 inches to about 0.015 inches. 
     
     
       25. The method of claim 22 wherein the size of .[.each.]. .Iadd.said further .Iaddend.vent comprises a thickness of from about 0.003 inches to about 0.010 inches. 
     
     
       26. A method according to claim 21, wherein said .[.selecting.]. .Iadd.providing .Iaddend.step comprises the step of selecting a .Iadd.further .Iaddend.vent .[.having a passageway and an obstruction in said passageway,.]. .Iadd.wherein .Iaddend.said obstruction and said passageway .[.combining.]. .Iadd.combine .Iaddend.to form an opening having a shape which causes the movement of the liquid foamable polymeric composition in the vent to be restricted. 
     
     
       27. A method according to claim 21, wherein said .[.selecting.]. .Iadd.providing .Iaddend.step includes the step of .[.selecting.]. .Iadd.providing .Iaddend.a passageway and an obstruction combining to form a plurality of openings between the obstruction and a wall of said passageway to cause the liquid foamable polymeric composition to move through said openings. 
     
     
       28. A method according to claim 27, wherein said venting step includes the step of venting the gases through a port which is in communication with said plurality of openings.