Process for producing a rigid polyurethane-isocyanurate foam
AssigneeBayer Intellectual Property GmbH
InventorsHartmut Nefzger, Jörg Hofmann, Klaus Lorenz, Stephanie Vogel, Reinhard Albers, Patrick Klasen
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Abstract
The invention provides a process for producing rigid polyurethane-polyisocyanurate foams using polyols having a high proportion of secondary hydroxyl end groups. The invention further relates to the rigid polyurethane-polyisocyanurate foams thus obtainable and to the use thereof in the production of composite elements from rigid polyurethane-polyisocyanurate foams and suitable outer layers. The invention further provides the composite elements thus obtainable.
Claims15
A process for producing a rigid polyurethane-polyisocyanurate foam C comprising the steps of
- (I) reacting a polyester comprising carboxyl end groups with an epoxide of general formula (1),
- where R1 represents alkyl or aryl,
- by obeying a molar ratio of epoxy groups to carboxyl end groups at between 0.8:1 and 50:1, to obtain a polyester polyol having secondary hydroxyl end groups A1a which has a functionality of 1.8 to 6.5, and a hydroxyl number of 15 mg KOH/g to 500 mg KOH/g;
- (II) foaming at isocyanate indexes of 180 to 400,
- (i) a polyol component A1 comprising A1a
- with
- (ii) an isocyanate component B comprising
- a) at least one isocyanate B1 selected from the group consisting of:
- tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylene polymethylene polyisocyanate, xylylene diisocyanate, naphthylene diisocyanate, hexamethylene diisocyanate,
- diisocyanatodicyclohexylmethane and isophorone diisocyanate,
- or
- b) an isocyanate-terminated prepolymer B2 prepared from at least a polyisocyanate B1 and an isocyanate-reactive compound,
- or
- c) mixtures of B1 and B2,
- in the presence of
- (iii) at least one blowing agent A2, and
- (iv) at least one catalyst A3, except that carbanionic catalysts shall be excluded.
Dependencies are inferred from the claim text.