Process for making a pellet
The invention comprises a shaping process for making pellets of a thermoplastic extrudable resin composition. The resin composition comprises a thermoplastic polymer, plasticizer and optionally further additives. The plasticizer comprises a component which is solid at room temperature. The process is run at a temperature above the melting point of the plasticizer and below the melting/plastification temperature of the thermoplastic polymer.
1. An extrusion process of making pellets of a thermoplastic extrudable resin composition consisting essentially of a thermoplastic polymer, plasticiser and optionally up to 4 wt % of one or more processing aids, the plasticiser consisting of a component which is solid at room temperature and a further auxiliary component selected from the group consisting of glycerine, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, and methyldiethyl amine, wherein:
the thermoplastic polymer is a water-soluble or water dispersible PVOH or a derivative thereof;
the temperature of the composition within the extruder does not at any time exceed a temperature which is 45° C. below the melting or plastification temperature of the thermoplastic polymer;
the extrusion process comprises extruding the composition into one or more strands, permitting the strands to cool under ambient conditions or with assisted cooling, and separating or partially separating the one or more strands into pellets by a method comprising cutting, twisting, partial cutting, pressing, nipping or perforating; and
the maximum temperature of the extrusion process, including the extrusion of the composition into the one or more strands, is above the melting point of the solid component of the plasticiser and below the melting or plastification temperature of the thermoplastic polymer.
2. A process according to claim 1 , wherein the plasticiser comprises at least 5 wt % of the mass of the thermoplastic extrudable resin composition.
3. A process according to claim 2 , wherein the plasticiser comprises at least 10 wt % of the mass of the thermoplastic extrudable resin composition.
4. A process according to claim 3 , wherein the plasticiser comprises at least 15 wt % of the mass of the thermoplastic extrudable resin composition.
5. A process according to claim 1 , wherein the particle size of raw materials used is below 2000 lam.
6. A process of manufacturing an injection molded water soluble pouch containing a detergent formulation, the method comprising the steps of: injection molding a water soluble pouch from pellets of a thermoplastic extrudable resin composition formed by the extrusion process of claim 1 .
7. A process according to claim 1 , wherein the one or more processing aids are selected from: mono-, di-, tri-carboxylic acids/salts thereof, fatty acids, mono-, di-, and tri glycerides/salts thereof, aerosol, inorganic pigments and organic pigments.
8. A process according to claim 1 , wherein the temperature of the extrudable resin composition within the extruder is at least 40° C.
9. A process according to claim 1 , wherein the temperature of the extrudable resin composition within the extruder is at least 50° C.
10. A process according to claim 6 , wherein the detergent formulation is an automatic washing machine detergent composition or an automatic dishwasher detergent composition.
11. A process according to claim 1 , wherein the at least one further auxiliary component comprises propylene glycol.
12. A process according to claim 1 wherein the strand or strands are separated by cutting or twisting the strand.
13. A process according to claim 1 wherein the strand or strands are partially separated by partial cutting, pressing, nipping or perforating.
14. A process according to claim 12 comprising twisting the strand at intervals when the strand is still plastic in order to form “sausages”.
15. A process according to claim 14 wherein the “sausages” are separated by breaking the connections between the “sausages” once they have become more brittle.