Spray-applied polyurethaneurea composites based on polyisocyanate prepolymers containing soft-segments

1. A composite article comprising:

(I) at least one layer comprising a sprayable polyurethaneurea composition which comprising:

(A) an isocyanate prepolymer having an NCO group content of about 15 to about 30% by weight, and which comprises the reaction product of

(1) one or more diphenylmethane diisocyanate which is optionally modified with allophanate groups and/or carbodiimide groups,

with

(2) a polyether polyol having a functionality of about 1.8 to about 3.5 and a molecular weight of about 1500 to about 8000;

and

(B) an isocyanate-reactive component comprising:

(1) no more than 5% by weight of one or more high molecular weight polyether polyols having a functionality of about 1.8 to about 3.5 and a molecular weight of about 1500 to about 8000;

(2) from about 90 to about 98% by weight of one or more crosslinking agents having a molecular weight of 200 to less than 1500 and a functionality of about 2.5 to about 8;

and

(3) from about 0.5 to 10% by weight of at least one chain extender having a functionality of about 2 and a molecular weight of about 60 to about 250;

with the sum of the %'s by weight of (B)(1), (B)(2) and (B)(3) totaling 100% by weight of component (B);

wherein components (A) and (B) are present in amounts such that the isocyanate index is about 95 to about 120

and

(II) at least one polyurethaneurea foam layer which is sprayable and comprises the reaction product of a polyisocyanate component, an isocyanate-reactive component and water.

2. The composite article of claim 1 , comprising alternating layers of (I) said sprayable polyurethaneurea, and (II) said polyurethaneurea foam.

3. The composite article of claim 1 , comprising

(I) two layers of sprayable polyurethaneurea,

and

(II) one polyurethaneurea foam layer,

with the foam layer positioned between the two layers of sprayable polyurethaneureas.

4. The composite article of claim 1 , wherein (I) the sprayable polyurethaneurea compositions additionally comprise one or more fillers.

5. The composite article of claim 1 , wherein (A)(1) said diphenylmethane diisocyanate comprises from 0 to 60% by weight of the 2,4′-isomer, from 0 to 6% by weight of the 2,2′-isomer and from 36 to 100% by weight of the 4,4′-isomer, with the sum of the %'s by weight of the isomers totaling 100% by weight.

6. The composite article of claim 1 , wherein the isocyanate component comprises a mixture of polyphenylmethylene polyisocyanate with (A) said isocyanate prepolymer.

7. A process for the production of a polyurethaneurea composite comprising:

(A) spraying (I) a polyurethaneurea composition onto a suitable substrate; wherein said polyurethaneurea comprises:

(a) an isocyanate prepolymer having an NCO group content of about 15 to about 30% by weight, and which comprises the reaction product of

(1) one or more diphenylmethane diisocyanate which is optionally modified with allophanate groups and/or carbodiimide groups,

with

(2) a polyether polyol having a functionality of about 1.8 to about 3.5 and a molecular weight of about 1500 to about 8000;

and

(b) an isocyanate-reactive component comprising:

(1) no more than 5% by weight of one or more high molecular weight polyether polyols having a functionality of about 1.8 to about 3.5 and a molecular weight of about 1500 to about 8000;

(2) from about 90 to about 98% by weight of one or more crosslinking agents having a molecular weight of 200 to less than 1500 and a functionality of about 2.5 to about 8;

and

(3) from about 0.5 to 10% by weight of at least one chain extender having a functionality of about 2 and a molecular weight of about 60 to about 250;

with the sum of the %'s by weight of (b)(1), (b)(2) and (b)(3) totaling, 100% by weight of component (b);

wherein components (a) and (b) are present in amounts such that the isocvanate index is about 95 to about 120;

and

(B) spraying (II) a polyurethaneurea foam forming composition onto the polyurethaneurea coated substrate in (A), in which the polyurethaneurea foam forming composition comprises the reaction product of a polyisocyanate, an isocyanate-reactive component and water.

8. The process of claim 7 , additionally comprising

(C) spraying a second layer of (I) the polyurethaneurea composition onto the polyurethaneurea foam layer formed in (B).

9. The process of claim 7 , wherein alternate layers of (I) the polyurethaneurea composition and (II) the polyurethaneurea foam are applied.