Method of preparing a mixture for making extruded resin articles
AssigneeJohns Manville
InventorsJoseph John Chelland, Fred Everett Love
Life of this patent
Estimating the term…
Abstract
A mixture to be used making an extruded resin article, specifically extruded polyvinyl chloride pipe, and a method of preparing this mixture are disclosed herein. The mixture includes a resin, specifically polyvinyl chloride (PVC), in particulate form and a nonresinous filler material, for example, calcium carbonate, also in particulate form dispersed throughout the PVC. The particles of filler material are adhered to adjacent PVC particles to reduce segregation of the two types of particles. The method by which these particles are adhered to each other includes the use of a second resin which is also in particulate form and which has a lower melting point than that of the PVC resin.
Claims10
In a method of making an extruded resin article, which method includes preparing a mixture including a first resin in particulate form with a non-resinous filler material in finer particulate form dispersed throughout said resin, air-conveying said mixture to the point at which the article is to be made from a remote location and making said article from said mixture by means of extrusion, the improvement comprising:
- a. providing a second resin in particulate form, said second resin being such that
- i. it has a melting point below that of said first-mentioned resin,
- ii. when initially heated to its melting point, said second resin will adhere to adjacent particles of said first-mentioned resin and filler material but will not be immediately absorbed by said adjacent particles, and
- iii. said second resin promotes fusion of said first resin during said extrusion;
- b. substantially uniformly mixing said particles of second resin throughout said particles of first resin prior to combining said filler material with said first resin to provide a substantially homogeneous mixture of the two;
- c. during said mixing step, heating said resins to the point at which said second resin initially melts such that the particles of second resin adhere to particles of the first resin;
- d. after said second resin has reached said melting point and before it has a chance to be completely absorbed by said first resin, dispersing said filler material substantially throughout said first and second resins such that the particles of filler material adhere to said second resin particles;
- and
- e. preventing said melted particles of second resin from being completely absorbed by said first resin particles or particles of filler material.
Dependencies are inferred from the claim text.