US 11,945,141 B2
Method for producing foamed flat moldings and mold for carrying out said method
Stefan Hopf, Monheim (DE); Stephan Moers, Brüggen (DE); Achim Wick, Cologne (DE); and Christian Windeck, Viersen (DE)
Assigned to Covestro Deutschland AG, Leverkusen (DE)
Appl. No. 17/608,233
Filed by Covestro Deutschland AG, Leverkusen (DE)
PCT Filed Jan. 11, 2021, PCT No. PCT/EP2021/050371
§ 371(c)(1), (2) Date Nov. 2, 2021,
PCT Pub. No. WO2021/144218, PCT Pub. Date Jul. 22, 2021.
Claims priority of application No. 20152534 (EP), filed on Jan. 17, 2020.
Prior Publication US 2022/0347897 A1, Nov. 3, 2022
Int. Cl. B29C 44/42 (2006.01); B29C 44/04 (2006.01); B29C 44/58 (2006.01); B29K 75/00 (2006.01)
CPC B29C 44/428 (2013.01) [B29C 44/04 (2013.01); B29C 44/588 (2013.01); B29K 2075/00 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A method for producing a production of foamed areal polyurethane/polyisocyanurate molding with a thickness (LF2) in a mold (10), comprising an inlet region, a cavity (100) and a depressurization unit (300), the method comprising:
i) injecting a polyurethane/polyisocyanurate reaction mixture through at least one inlet aperture (110, 210) in the inlet region and into the cavity (100) of the mold (10), said cavity being under an initial pressure of 5 bar to 40 bar,
ii) after the injection of the polyurethane/polyisocyanurate reaction mixture, carrying out a depressurization in the cavity (100) for 0.1 to 10 seconds by means of at least one valve (310) in the depressurization unit (300), to atmospheric pressure or to a pressure which is lower than the initial pressure and which is 1 bar to 5 bar, wherein the polyurethane/polyisocyanurate reaction mixture foams along a main flow direction from the inlet region through the cavity (100) to the depressurization unit (300), and
iii) hardening, cooling and demolding the foamed areal polyurethane/polyisocyanurate molding, wherein
the cavity has two long dimensions (LF1 and LF3) and one dimension (LF2) that is short in comparison therewith, and one of the long dimensions (LF3) represents the main flow direction of the foam,
the cavity (100) has at least one wall (A3) in the plane which contains the dimensions (LF1) and (LF2), or has at least one portion (K2) of a wall (A2) in a plane which contains the dimensions (LF1) and (LF3), where the at least one portion (K2) of the wall (A2) corresponds to the area which extends in the dimension (LF3) across that one-tenth part of the wall (A2) that is opposite to the inlet region, and where the at least one wall (A3) or at least one portion (K2) of a wall (A2) has at least one aperture (340) which connects the cavity (100) and the depressurization unit (300),
the ratio of the sum of the areas of the at least one aperture (340) to the area of the wall (A3) comprising said aperture or of the at least one portion (K2) of the wall (A2), where said at least one portion (K2) comprises said aperture, is 1:20 to 1:100,
the at least one aperture (340) has a length (LS1) in the direction of the long dimension (LF1) of the cavity (100), and
the ratio of the length (LS1) or, respectively, of the sum of the length (LS1) of the at least one aperture (340) to the long dimension (LF1) of the cavity (100) is greater than 1:4.