Polyurethane foams having an integral skin using a mixture of polyols as the chain extender
AssigneeBayer Aktiengesellschaft
InventorsHermann Schafer, Christian Weber
Life of this patent
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Abstract
This invention relates to a process for making polyurethane elastomer moldings from A. organic polyisocyanates B. polyhydroxyl compounds having molecular weights in the range from about 1800 to about 10,000, C. a chain extender, D. a blowing agent and E. optionally the auxiliaries and additives commonly used in making polyurethanes, The improvement wherein said chain extender (c) is a polyol mixture comprising I. ethylene glycol and Ii. at least one other polyol having a molecular weight below 1800 and wherein said polyol mixture has an average molecular weight below about 600.
Claims10
In a process for the production of polyurethane elastomer moldings having a compact peripheral zone and a cellular core by the in-mold foaming of a foamable reaction mixture which comprises
- a. organic polyisocyanate,
- b. polyhyroxyl compounds having molecular weights in the range from about 1800 to about 10,000,
- c. a chain extender,
- d. a blowing agent, and
- e. optionally the auxiliaries and additives commonly used in making polyurethanes, the improvement wherein said chain extender (c) is a polyol mixture comprising
- i. ethylene glycol,
- ii. at least one other polyol having a molecular weight of below 1800,
- and wherein said polyol mixture has an average molecular weight below about 600, wherein said component (ii) is used in quantities of from 5 to 30% by weight, based on the sum total of (i) plus (ii), wherein said chain extender (c) is used in quantities of from 10 to 30% by weight, based on component (b), and wherein polyisocyanate (a) is used in such a quantity that the foamable mixture has an isocyanate value of 90 to 120.
A polyol mixture useful in the preparation of polyurethanes which comprises
- 1. 70-90% by weight of a mixture of
- A. a linear polyether obtained by the addition of propylene oxide and then ethylene oxide with propylene glycol and
- B. a polyether obtained by the addition of propylene oxide and then ethylene oxide with trimethylol propane
- wherein the mixture has a molecular weight of from about 1800 to about 10,000,
- 2. 10-30% of a chain extender which comprises:
- C. 70-95% ethylene glycol and
- D. 5-30% of at least one other polyol having a molecular weight below 1800
- wherein said chain extender has a molecular weight below about 600.
Dependencies are inferred from the claim text.