Process and apparatus for compounding and injection-moulding desiccant-filled polymers

• US 7,744,788 B2
• Filed: 03/12/2008
• Issued: 06/29/2010
• Est. Priority Date: 03/12/2007
• Status: Active Grant

• Current Assignee: Airnov, Inc. (Colorcon Incorporated)
• Original Assignee: Airsec Sas (Clariant AG)
• Inventors: Portier, Benoit, Logel, Valere
• Primary Examiner(s): HEITBRINK, JILL LYNNE
• Application Number:
  US12/046,499
• Publication Number:
  US 20080224341A1
• Time in Patent Office: 839 Days
• Field of Search: 264/40.1, 264/328.17, 264/328.18, 425/145, 425/146, 425/169
• US Class Current: 264/40.1
• CPC Class Codes: B29C 2045/466 supplying the injection unit directly by a compounder
• CPC Class Codes: B29C 2945/7605 Viscosity
• CPC Class Codes: B29C 2945/76063 MFI, MFR
• CPC Class Codes: B29C 2945/7618 Injection unit
• CPC Class Codes: B29C 2945/76809 raw material feeding devices
• CPC Class Codes: B29C 2945/76832 raw materials
• CPC Class Codes: B29C 45/0013 using fillers dispersed in the moulding material, e.g. metal particles
• CPC Class Codes: B29C 45/1816 Feeding auxiliary material, e.g. colouring material
• CPC Class Codes: B29C 45/54 and plasticising screw B29C45/532 takes precedence
• CPC Class Codes: B29C 45/7646 viscosity

Abstract

Disclosed is an injection moulding machine, comprising an extruder for continuously producing a melt of a desiccant-filled polymer; at least one injection device fluidly connected with the extruder by a first conduit to receive melt and including an injection ram movable to a forward position for injection of melt into an injection mould and a rear position for introduction of melt into the injection device; characterized in that the injection moulding machine further comprises a sensor which allows determination of the viscosity or melt flow index of the desiccant-filled polymer. Further disclosed is a method of operating such a compounder-type injection moulding machine.

Claims

1. A method of operating an injection moulding machine having an extruder for continuously producing a melt of a desiccant-filled polymer and with at least one injection device fluidly connected with the extruder and including an injection ram, comprising the steps of;

Ascertaining a viscosity or melt flow index downstream of an outlet of the extruder by a sensor which allows determination of viscosity or melt flow index;

Comparing the viscosity or melt flow index with a given desired viscosity or melt flow index;

Generating a control signal in response to a deviation between the ascertained viscosity or melt flow index and the desired viscosity or melt flow index; and

adjusting in response to the control signal the desiccant load in the polymer to adjust the viscosity or melt flow index to a level corresponding with the desired viscosity or melt flow index value.

2. Method according to claim 1, wherein the percentage of desiccant load in the overall polymer composition is above 15 wt.-%, based on the total weight of the desiccant-filled polymer composition.

3. Method according to claim 1, wherein the percentage of desiccant load in the overall polymer composition is above 25 wt.-%, based on the total weight of the desiccant-filled polymer composition.

4. Method according to claim 1, wherein the percentage of desiccant load in the overall polymer composition is above 35 wt.-%, based on the total weight of the desiccant-filled polymer composition.

5. Method according to claim 1, wherein the percentage of desiccant load in the overall polymer composition is above 45 wt.-%, based on the total weight of the desiccant-filled polymer composition.

6. Method according to claim 1, wherein the percentage of desiccant load in the overall polymer composition is above 50 wt.-%, based on the total weight of the desiccant-filled polymer composition.

8. The injection moulding machine of claim 1, wherein the sensor is arranged downstream of the extruder.

9. The injection moulding machine of claim 1, wherein the sensor is included in an instrumented injection nozzle.

10. The injection moulding machine of claim 1, wherein the control or drive mechanism is positioned at a compounding unit or dosing unit in order to influence the mixing ratio of polymer and desiccant.

11. The injection moulding machine of claim 1, further comprising

a control unit receiving the signal from the pressure sensor;

and

a drive mechanism operated by the control unit for actively moving the injection ram backwards in response to the signal according to a predetermined algorithm.

7. An injection moulding machine, comprising:

an extruder for continuously producing a melt of a desiccant-filled polymer;

at least one injection device fluidly connected with the extruder by a first conduit to receive melt and including an injection ram movable to a forward position for injection of melt into an injection mould and a rear position for introduction of melt into the injection device,

mechanism for providing and mixing at least one desiccant and at least one polymer,

mechanism to regulate or adjust the pressure of the melt to a desired value, and mechanism to regulate or adjust the temperature of the melt to a desired value,

characterized in that the injection moulding machine further comprises a sensor which allows determination of the viscosity or melt flow index of the desiccant-filled polymer melt, the sensor being a pressure sensor, disposed in a location selected from the group consisting of inside the extruder, downstream of the extruder, and an area between the extruder and the injection device, for ascertaining a melt pressure state downstream of an outlet of the extruder and outputting a signal commensurate with the melt pressure state,

a control unit receiving a signal from the sensor, and

a control or drive mechanism operated by the control unit for changing the desiccant load in the polymer according to a predetermined algorithm.