Methods of Manufacturing Formaldehyde-Free Molded Products and Related Parts

Abstract

The present invention provides a moldable mixture containing large portion of agricultural fibers and small portion of a binding agent and a flow-promoting filler material. The moldable mixture is substantially free of formaldehyde, with low moisture content and high draw ratio. The present invention also provides methods of manufacturing molded products and related parts, based on the claimed moldable mixture. Molded products ( 830 ) and related parts such as runner ( 810 ) and plank ( 820 ) with light weight, high density and more complex profile are manufactured by the claimed methods including steps of providing required materials for a moldable mixture, mixing the provided materials to form a moldable mixture, shaking the moldable mixture in preparing for compression molding and compression molding the moldable mixture to form molded products and related parts.

We claim: 
     
         1 . A moldable mixture comprising a binding agent, a flow-promoting filler material and an agricultural fiber, wherein said moldable mixture is in the absence of hardener, impact modifier, co-solvent and de-molding agent. 
     
     
         2 . The moldable mixture of  claim 1 , wherein said binding agent is Diisocyanate-diphenylmethane with an amount not more than 5% by weight to said moldable mixture. 
     
     
         3 . The moldable mixture of  claim 2 , wherein the said binding agent is substantially free of formaldehyde. 
     
     
         4 . The moldable mixture of  claim 1 , wherein said agricultural fiber is at least one agricultural fiber selected from a group consisting of rape straw and rice stalk. 
     
     
         5 . The moldable mixture of  claim 4 , wherein said agricultural fiber is between 85% to 95% by weight to said moldable mixture. 
     
     
         6 . The moldable mixture of  claim 1 , wherein said flow-promoting filler material is wheat flour which is less than 10% by weight to said moldable mixture. 
     
     
         7 . The moldable mixture of  claim 1 , wherein said binding agent is a soy-based binding agent with an amount not more than 5% by weight to said moldable mixture. 
     
     
         8 . A method of manufacturing a molded product comprising the steps of:
 a. Providing an agricultural fiber, a binding agent and a flow-promoting filler material;   b. Mixing said agricultural fiber with said flow-promoting filler material and said binding agent to form a moldable mixture;   c. Shaking said moldable mixture in preparation for compression molding;   d. Compression molding said moldable mixture to form molded product.   
     
     
         9 . The method of  claim 8 , wherein said mixing further comprises spraying said binding agent at pressure between 5 to 8 bar into said agricultural fiber with said flow-promoting filler material, wherein said binding agent is Diisocyanate-diphenylmethane with an amount not more than 5% by weight to said moldable mixture. 
     
     
         10 . The method of  claim 8 , wherein said binding agent is a soy-based binding agent with an amount not more than 5% by weight to said moldable mixture. 
     
     
         11 . The method of  claim 8 , wherein said agricultural fiber is at least one agricultural fiber selected from a group consisting of rape straw and rice stalk. 
     
     
         12 . The method of  claim 8 , wherein said agricultural fiber is between 85% to 95% by weight to said moldable mixture. 
     
     
         13 . The method of  claim 8 , wherein said flow-promoting filler material is wheat flour which is less than 10% by weight to said construction molding mixture. 
     
     
         14 . The method of  claim 8 , wherein said mixing takes place in the absence of hardener, impact modifier, co-solvent and de-molding agent. 
     
     
         15 . The method of  claim 8 , wherein said shaking further comprises discharging said moldable mixture from a material loading station into a material feeding tray with a shaking motion. 
     
     
         16 . The method of  claim 15 , wherein said discharging is followed by transferring said moldable mixture from said material feeding tray to a mold with a shaking motion in preparation for compression molding. 
     
     
         17 . The method of  claim 8 , wherein said compression molding is performed as a single compression stroke. 
     
     
         18 . The method of  claim 17 , wherein said single compression stroke is performed with a draw ratio from 1 to 10. 
     
     
         19 . The method of claim of  8 , wherein said compression molding is performed at a temperature from 200 to 230 degree Celsius. 
     
     
         20 . The method of claim of  8 , wherein said compression molding is performed at a pressure from 0.30 to 0.40 kg/mm 2 .