Thermosetting molding compositions containing polyurethane and a fibrous material, and a process for the production of moldings

Claim 2

Substantially solvent-free molding compositions comprising: (A) from 25 to 91% by weight, based on the weight of the molding composition, of a polyhydroxyl prepolymer having a viscosity of at least 20 Pa.s/25° C. andcontaining from 0.5 to 7% by weight, based on the prepolymer, of free hydroxyl groups, from 5 to 20% by weight, based on the prepolymer, of urethane groups, and from 0 to 2.5% by weight, based on the prepolymer, of urea groups, (B) from 4 to 15% by weight, based on the weight of the molding composition, of a polyisocyanate having a melting point above 100° C. and (C) from 5 to 60% by weight of an organic or inorganic fibrous material having an average fiber length of from 10 to 100 mm, the NCO/OH equivalent ratio (taking into account any masked NC0-groups) of components A and B amounting to between 1:1 and 1:1.75.

Claim 3

The composition of claim 1 further containing from 1 to 5% by weight, based on the prepolymer, of a molecular sieve of the sodium aluminum silicate type and from 0.1 to 5% by weight, based on the prepolymer, of one or more activators.

Claim 4

The composition of claim 1, characterized in that component (A) contains from 1.5 to 4% by weight of hydroxyl groups and from 10 to 15% by weight of urethane groups.

Claim 5

The composition of claim 1, characterized in that component (B) is a diisocyanate containing uretdione groups.

Claim 6

The composition of claim 4, characterized in that component (B) is dimeric tolylene diisocyanate.

Claim 7

The composition of claim 1, characterized in that component (C) is a glass fiber material having an average length of from 20 to 60 mm.

Claim 8

A process for the production of fiber-reinforced polyurethane-based moldings comprising: (A) reacting at a temperature of from 10° to 50° C., (i) a polyisocyanate liquid at the reaction temperature, (ii) from 80 to 97% by weight, based on the sum of components (ii) to (iv), of one or more compounds containing from 2 to 8 hydroxyl groups and having a molecular weight of from 300 to 10,000, (iii) from 3 to 15% by weight, based on the sum of components (ii) to (iv) of a chain-extending agent containing from 2 to 4 hydroxyl groups and having a molecular weight of from 62 to 250 and, optionally, (iv) from 0 to 5% by weight, based on the sum of components (ii) to (iv) of a compound containing from 2 to 4 amino groups having isocyanate-reactive hydrogen atoms or an equivalent quantity of water, to form a polyhydroxyl prepolymer, wherein said components (ii) to (iv) are liquid at the reaction temperature selected and have a mean functionality of isocyanate-reactive groups of from 2.0 to 2.6, and wherein the equivalent ratio between NCO-groups of component (i) and NCO-reactive hydrogen atoms of components (ii) to (iv) is from 0.4:1 to 0.85:1, with the proviso that if the said equivalent ratio is below 0.5:1 the said mean functionality of components (ii) to (iv) is at least 2.1 and if the said equivalent ratio is above 0.65:1, the said mean functionality is no more than 2.4; (B) adding to said prepolymer during and/or after step (A), (v) a polyisocyanate having a melting point above 100° C. and (vi) a fibrous material having an average length of from 10 to 100 mm; and (c) hardening the product thus obtained at a temperature above 90° C. and under a pressure of from 20 to 400 bars.

Claim 9

A process for the production of fiber-reinforced polyurethane-based moldings comprising: (A) reacting at a temperature of from 10° to 50° C., (i) a polyisocyanate liquid at the reaction temperature, (ii) from 80 to 97% by weight, based on the sum of components (ii) to (iv), of one or more compounds containing from 2 to 8 hydroxyl groups and having a molecular weight of from 300 to 10,000, (iii) from 3 to 15% by weight, based on the sum of components (ii) to (iv) of a chain-extending agent containing from 2 to 4 hydroxyl groups and having a molecular weight of from 62 to 250 and, optionally, (iv) from 0 to 5% by weight, based on the sum of components (ii) to (iv) of a compound containing from 2 to 4 amino groups having isocyanate-reactive hydrogen atoms or an equivalent quantity of water, to form a polyhydroxyl prepolymer, wherein said components (ii) to (iv) are liquid at the reaction temperature selected and have a mean functionality of isocyanate-reactive groups of from 2.0 to 2.6, and wherein the equivalent ratio between NCO-groups of component (i) and NCO-reactive hydrogen atoms of components (ii) to (iv) is from 0.4:1 to 0.85:1, with the proviso that if the said equivalent ratio is below 0.5:1 the said mean functionality of components (ii) to (iv) is at least 2.1 and if the said equivalent ratio is above 0.65:1, the said mean functionality is no more than 2.4; (B) adding to said prepolymer during and/or after step (A), (v) a polyisocyanate having a melting point above 100° C. and (vi) a fibrous material having an average length of from 10 to 100 mm; and (c) hardening the product thus obtained at a temperature above 90° C. and under a pressure of from 20 to 400 bars.

Claim 10

The process of claim 7 wherein from 1 to 5% by weight, based on the prepolymer, of a molecular sieve of the sodium aluminum silicate type and or from 0.1 to 5% by weight, based on the prepolymer, of one or more activators are added at step (B).

Claim 11

The process of claim 7, characterized in component (II) comprises a mixture of (a) from 45 to 90% by weight, based on the sum of components (ii) to (iv), of one or more polyols having a molecular weight of from 1000 to 10,000 and (b) from 1 to 45% by weight, based on the sum of components (ii) to (iv), of one or more polyols having a molecular weight of from 300 to 950.

Claim 12

The process of claim 9, characterized in said mixture comprises (a) from 50 to 80% by weight, based on the sum of components (ii) to (iv), of one or more polyols having a molecular weight of from 2000 to 8000 and (b) from 5 to 35% by weight of one or more polyols having a molecular weight of from 350 to 800.

Claim 13

The process of claim 7, characterized in that a diamine having a molecular weight below 200 is used as component (iv).

Claim 14

The process of claim 7, characterized in that a powder-form diisocyanate containing uretdione groups and having a particle size of less than 40μ is used as component (v).