VARIABLE DEVICE AND METHOD FOR APPLYING A FOAMABLE REACTION MIXTURE TO A MOVING COVER LAYER

Abstract

The invention relates to a device for applying a foamable reaction mixture to a moving cover layer, comprising a mixing head (100) having at least two inlets (200, 300) and at least one outlet (400) for mixing components that produce the foamable reaction mixture, and a conduit (410, 420, 430, 440) connected to the outlet of the mixing head, through which conduit the foamable reaction mixture can flow, and which has a discharge element (500), from which the foamable reaction mixture can be applied to the cover layer. The conduit (410, 420, 430, 440) is designed to include at least two configurations, which differ in the path length, which the reaction mixture flowing through the conduit covers. The invention further relates to a method for applying a foamable reaction mixture to a moving cover layer using a device according to the invention.

Claims

1. An apparatus for applying a foamable reaction mixture to a moving outerlayer, comprising: a mixing head having at least two inlets and at least one outlet for mixing components forming the foamable reaction mixture; and a conduit connected to an outlet of the mixing head through which the foamable reaction mixture can flow and which has a discharging element from which the foamable reaction mixture may be applied to the outerlayer, wherein the conduit is adapted to encompass at least two configurations which differ in the path length traversed by the reaction mixture flowing through the conduit.

2. The apparatus as claimed in claim 1, wherein the conduit is adapted to encompass continuously variable path lengths.

3. The apparatus as claimed in claim 2, wherein the conduit has an inner part and a coaxial outer part arranged over the inner part, and the inner part and the outer part are movable with respect to one another along their common axis.

4. The apparatus as claimed in claim 1, wherein the conduit is adapted to encompass a plurality of discrete configurations each having different path lengths.

5. The apparatus as claimed in claim 4, wherein the conduit at least partially passes through a multiport valve.

6. A process for applying a foamable reaction mixture that exhibits a change in its viscosity over time to a moving outerlayer, comprising: determining a desired viscosity of the reaction mixture at the time of application to the outerlayer; configuring the application apparatus of claim 1 such that the path length of the conduit correlates with the desired viscosity of the reaction mixture at the time of application to the outerlayer; providing the reaction mixture in the mixing head of the application apparatus; and moving the reaction mixture from the mixing head through the conduit and out of the discharging element of the application apparatus onto the outerlayer.

7. The process as claimed in claim 6, wherein the reaction mixture comprises 20% by weight of a component having a viscosity measured at 25 C. by rotational viscometry according to DIN 53019 of 2500 mPas.

8. The process as claimed in claim 6, wherein the reaction mixture comprises a polyol, a polyisocyanate and a blowing agent.

9. The process as claimed in claim 8, wherein the reaction mixture contains an amine catalyst and for a predetermined value of the viscosity of the reaction mixture upon exiting the discharging element, the content of the amine catalyst in the reaction mixture for the configuration of the conduit having the longest path length is 90% of the content in the reaction mixture for the configuration of the conduit having the shortest path length.

10. The process as claimed in claim 6, wherein the path length of the conduit is altered during application of the reaction mixture.

Description

[0051] The present invention is more particularly elucidated with reference to the figures which follow without, however, being limited thereto.

[0052] FIG. 1 shows a first apparatus according to the invention in a first configuration

[0053] FIG. 2 shows the first apparatus according to the invention in a second configuration

[0054] FIG. 3 shows a second apparatus according to the invention in a first configuration

[0055] FIG. 4 shows the first apparatus according to the invention in a second configuration

[0056] FIG. 5 shows a detail view of a third apparatus according to the invention in a first configuration

[0057] FIG. 6 shows a detail view of the third apparatus according to the invention in a second configuration

[0058] In one embodiment of the apparatus according to the invention the conduit is adapted to encompass continuously variable path lengths. This may be achieved for example when the conduit has an inner part and a coaxial outer part arranged over the inner part and the inner part and the outer part are movable with respect to one another along their common axis. Such a variant is shown in FIGS. 1 and 2.

[0059] FIG. 1 shows a first apparatus according to the invention having a mixing head 100 comprising two inlets 200, 300 and an outlet 400. The mixing head is presently in the form of a static mixer and may be used for example to mix a polyol stream and an isocyanate stream to obtain a reaction mixture reacting to afford a PUR/PIR foam. The conduit connected to the outlet 400 of the mixing head 100 has an inner part 410 which initially receives the reaction mixture flowing from the outlet 400. An outer part 420 fits coaxially around the inner part 410. Parts 410 and 420 are movable along their common axis.

[0060] Optional seals (not shown) can prevent discharge of reaction mixture through any gap present between parts 410 and 420. The end 500 of the outer part 420 opposite the outlet 400 forms the discharging element of the apparatus. A discharging element such as a rate applicator or a slot die may alternatively be attached to the end 500.

[0061] The apparatus in FIG. 1 is configured for a relatively short delay time path. Pulling apart the outer part 420, as shown in FIG. 2, allows a longer delay time path to be realized. It is readily apparent that the delay time path is continuously variable.

[0062] FIG. 3 shows a second first apparatus according to the invention having a mixing head 100 comprising two inlets 200, 300 and an outlet 400. The mixing head is presently in the form of a static mixer and may be used for example to mix a polyol stream and an isocyanate stream to obtain a reaction mixture reacting to afford a PUR/PIR foam. The conduit connected to the outlet 400 of the mixing head 100 has an inner part 410 which initially receives the reaction mixture flowing from the outlet 400. A straight section of an outer part 440 fits coaxially around the inner part 410. Parts 410 and 440 are movable along their common axis. The outer part comprises a U-bend and further fits coaxially around the second inner part 430 of the conduit. This arrangement is comparable to a slide trombone.

[0063] Optional seals (not shown) can prevent discharge of reaction mixture through any gap present between parts 410, 430 and 440. The end 500 of the second inner part 430 forms the discharging element of the apparatus. A discharging element such as a rate applicator or a slot die may alternatively be attached to the end 500.

[0064] FIG. 4 shows the apparatus from FIG. 3 in which the delay time path has been enlarged by moving the outer part 440.

[0065] In a further embodiment of the apparatus according to the invention the conduit is adapted to encompass a plurality (for example 2, 3, 4, 5, 6 or 7) of discrete configurations each having a different path length. This may be effected for example when the apparatus at least partially passes through a multiport valve. Such a variant is shown in FIGS. 5 and 6.

[0066] FIG. 5 shows a 6-way valve or 6-way cock as a detail view of an apparatus according to the invention. The valve comprises three pairs of openings fluidically connected to one another by channels: openings 610/620, openings 630/640 and openings 650/660.

[0067] In the configuration shown in FIG. 5 of a long delay time path, material stream 700 which comes directly or indirectly from the mixing head enters inlet 610, exits through inlet 620, passes through the external conduit up to inlet 650 and exits the valve via inlet 660 to be applied to the outerlayer in the process via a discharging element. The material stream 710 may be for example a solvent for rinsing the valve and enters the valve via inlet 630 and exits the valve again via inlet 640.

[0068] To shorten the delay time path the valve shown in FIG. 5 may be rotated by 60, thus leaving unchanged the position of the external conduit previously traversed by material stream 700. This new configuration is shown in FIG. 6.

[0069] In FIG. 6 the material stream 700 comprising the reaction mixture takes the short path in through inlet 610 and out of the valve through inlet 660. Material stream 710, once more in the form of a solvent for rinsing for example, enters the valve via inlet 630, exits said valve via inlett 620, traverses the external conduit, reenters the valve via inlet 650 and finally exits said valve via inlet 640.

[0070] It will be appreciated that two or more multiport cocks may also be connected in series, thus avoiding a return to a configuration lacking a delay time element.

[0071] It will further be appreciated that embodiments such as are described in connection with FIGS. 1 to 4 may also be combined with the multiport cock.