Hard, optically clear polyurethane articles
First Claim
1. A polyurethane composition substantially free of ether linkages characterized by being heat curable to yield hard, impact-resistant articles having a Shore D hardness at room temperature of at least 75, said articles having a heat distortion temperature as determined according to ASTM D-648 of at least 190°
- F. (88°
C.) and showing no visual change when exposed to ultraviolet light in accordance with ASTM G-25-70, Method A, comprising the reaction product of;
(A) a cycloaliphatic polyisocyanate,(B) a low molecular weight active hydrogen-containing material containing only two active hydrogens per molecule,(C) a low molecular weight active hydrogen-containing material having at least three active hydrogens per molecule, and optionally,(D) a polymeric polycarbonate diol;
the equivalent ratio of (B)/(C) being within the range of 0.5 to 10/1, said reaction product having a calculated weight percentage of urethane linkages of at least 20 percent, a calculated molecular weight between branch points of 600-4,000 and the percentage by weight of cycloaliphatic structural units being within the range of 45 to 50.
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Abstract
Polyurethane compositions characterized by being heat curable to yield hard, impact-resistant articles having a high heat distortion temperature are disclosed. The cured polyurethane articles are transparent and also hydrolytic and UV light stable as well as being abrasion resistant. The polyurethane is prepared from a cycloaliphatic polyisocyanate, low molecular weight active hydrogen-containing material and optionally a polycarbonate diol. The weight percentage of the urethane moieties and the crosslinked density are carefully controlled so as to provide the proper balance of physical properties, particularly between hardness, flexibility and heat distortion temperature. The polyurethane articles are particularly useful in glazing applications such as aircraft glazing.
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Citations
21 Claims
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1. A polyurethane composition substantially free of ether linkages characterized by being heat curable to yield hard, impact-resistant articles having a Shore D hardness at room temperature of at least 75, said articles having a heat distortion temperature as determined according to ASTM D-648 of at least 190°
- F. (88°
C.) and showing no visual change when exposed to ultraviolet light in accordance with ASTM G-25-70, Method A, comprising the reaction product of;(A) a cycloaliphatic polyisocyanate, (B) a low molecular weight active hydrogen-containing material containing only two active hydrogens per molecule, (C) a low molecular weight active hydrogen-containing material having at least three active hydrogens per molecule, and optionally, (D) a polymeric polycarbonate diol;
the equivalent ratio of (B)/(C) being within the range of 0.5 to 10/1, said reaction product having a calculated weight percentage of urethane linkages of at least 20 percent, a calculated molecular weight between branch points of 600-4,000 and the percentage by weight of cycloaliphatic structural units being within the range of 45 to 50. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
- F. (88°
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21. A polyurethane composition substantially free of ether linkages characterized by being heat curable to yield hard, impact-resistant articles having a Shore D hardness at room temperature of at least 75, said articles having a heat distortion temperature according to ASTM D-648 of at least 190°
- F. (88°
C.) and showing no visual change when exposed to ultraviolet light in accordance with ASTM G-25-70, comprising the reaction product of;(A) 4,4'"'"'-methylene-bis(cyclohexyl isocyanate), (B) a low molecular weight active hydrogen-containing material selected from the class consisting of ethylene glycol, 1,4-butanediol and 1,6-hexanediol and mixtures thereof, (C) trimethylolpropane;
the equivalent ratio of (A) to (B) and (C) being about 1 to 1, the equivalent ratio of (B) to (C) being within the range of 0.5 to 10/1;
said reaction product having a calculated weight percentage of urethane linkages of at least 20 percent, a calculated molecular weight between branch points of 600-4000 and the percentage by weight of the cycloaliphatic structural units being within the range of 45 to 50.
- F. (88°
Specification