Device and method for preparing a liquid polymer blend

Abstract

A device for preparing a liquid polymer blend is proposed having a storage container for the liquid polymer blend; a degassing device, which is arranged downstream of the storage container, for the liquid polymer; a gassing device, which is arranged downstream of the degassing device, for adding an additive gas to the liquid polymer blend; a homogenization unit, which is arranged downstream of the gassing device, for the polymer blend to which the additive gas was added; and an output line, which is connected to the homogenization unit, for the homogenized polymer blend.

Claims

1. A method for preparing a liquid polymer blend, comprising the steps of: degassing the liquid polymer blend; subsequently aerating the degassed liquid polymer blend with an additive gas; homogenizing the liquid polymer blend provided with the additive gas; supplying the homogenized liquid polymer blend to a container having a stirring unit; storing temporarily the homogenized liquid polymer blend in the container, stirring the homogenized liquid polymer blend while in the container; providing the homogenized liquid polymer blend to a processing station via a pipe connected to the container, further comprising the steps of: measuring a mass flow of the liquid polymer blend after the degassing step, determining an amount of the additive gas as a function of the measured mass flow of the liquid polymer blend, and adding the amount of determined additive gas to the degassed liquid polymer blend.

2. The method according to claim 1, wherein the homogenizing takes place in a colloid mill.

3. The method according to claim 1, wherein the degassing takes place in a vacuum ventilator.

4. The method according to claim 1, wherein the liquid polymer blend comprises a polyol suitable for use in the production of a polyurethane system.

5. The method according to claim 1, wherein the additive gas comprises carbon dioxide and/or air.

6. The method according to claim 1, further comprising the step of maintaining the fill level of the container between two predetermined levels.

7. The method according to claim 6, wherein the maintaining of the fill level is achieved by sensing the fill level at the two predetermined levels and signaling to start or stop the supplying.

Description

BRIEF DESCRIPTIONS OF THE DRAWING

(1) An exemplary embodiment of a device according to the invention is illustrated in the drawing in a schematically simplified manner and is further described in the following description.

DETAILED DESCRIPTION

(2) The only FIGURE of the drawing illustrates a device according to the invention for carrying out a method for preparing a liquid polyol compound.

(3) In the drawing, a device 10 for preparing a polyol compound is illustrated, which represents a reaction polymer for a polyurethane system which serves for producing a plastic foam edge of a sliding roof lid of a roof opening system for a motor vehicle.

(4) The device 10 comprises a storage container 12, in which the polyol compound can be stored and which is provided with a stirrer 14 in order to cancel out any layering of the polyol compound caused by storage. The storage container 12 is connected to a degassing device 20, which is formed by a vacuum ventilator, via a pipe 16, in which a supply pump 18 is arranged. An output pipe 22, in which another supply pump 24 and a mass flow meter 26 are arranged and which leads to a homogenization unit 28 formed by a toothed colloid mill, is connected to the vacuum ventilator. A dosing valve 52, via which an additive gas can be added to the polyol compound and which is part of a gassing device, is arranged at the pipe 16 upstream of the homogenization unit 28.

(5) The homogenization unit 28 comprises an output pipe 30, which leads into a container 32 in which the prepared polymer blend is stored temporarily and which is provided with a stirrer unit 34. A positive pressure between 1 and 6 bars is realized in the container 32. The output pipe 30 leads such into the container 32 that the prepared polymer blend is supplied to the polymer blend already in the container 32 below the level of the latter polymer blend. The level or rather the filling level of the polymer blend in the container 32 is always kept between two marks, of which a lower one is provided with a first sensor 36 and an upper one is provided with a second sensor 38. The sensor 36 allocated to the lower mark gives a signal when the nominal filling level in the container 32 is fallen below and further liquid has to be prepared. The second sensor 38 allocated to the upper mark gives a signal when the nominal filling level is exceeded and the preparation of the liquid polymer blend has to be stopped by means of the device 10.

(6) The container 32 is connected to processing stations for the polyol compound via a flow pipe 40, said processing stations each being allocated to a foaming tool for producing a plastic frame of a sliding roof lid, and an isocyanate being added to the polyol compound in the processing stations in order to form a polyurethane system. Moreover, a return pipe 42, which forms a ring pipe in conjunction with the flow pipe 40 for supplying the processing stations, leads into the container 32.

(7) In order to control the preparation of the polyol compound, the device 10 comprises a control device 44, which is connected to the mass flow meter 26 via a pipe 46 and is connected to a gas mass flow meter 50 also allocated to the gassing device and to the dosing valve 52 via a pipe 48; carbon dioxide can be added to the liquid polyol compound as an additive gas by means of the dosing valve 52, and this upstream of the homogenization unit 28 and downstream of the mass flow meter 26.

(8) The method for preparing the polyol compound, which can be carried out by means of the device 10, can be realized in the subsequently described manner.

(9) The polyol compound, which is stirred in the storage container 12, is supplied in the degassing device 20 by means of the supply pump 18 and is freed of undefined gas charges there. Subsequently, the degassed polymer blend consisting of the polyol compound is supplied through the output pipe 22 by means of the supply pump 24. For this purpose, the amount of the polyol compound is first detected by means of the mass flow meter 26 and carbon dioxide is subsequently added via the gas mass flow meter 50 and the dosing valve 52 by means of the control device 44 as a function of the measurement. Downstream of the dosing valve 52, the polyol compound, to which carbon dioxide has been added, is guided through the homogenization unit 28 in order to disperse gas bubbles, which are formed from the carbon dioxide, in the polyol compound. The thus prepared polyol compound is then guided into the container 32 via the output pipe 30 so that it can be further processed, in particular being able to be further processed by adding an isocyanate to a polyurethane system, which can be used for producing a hard-foam edge of a sliding roof lid or similar.

LIST OF REFERENCES

(10) 10 device 12 storage container 14 stirrer 16 pipe 18 delivery pump 20 degassing device 22 output pipe 24 supply pump 26 mass flow meter 28 homogenization unit 30 output pipe 32 container 34 stirring device 36 sensor 38 sensor 40 flow pipe 42 return pipe 44 control device 46 pipe 48 pipe 50 gas mass flow meter 52 dosing valve