Pipes comprising β-nucleated propylene copolymers

1. A propylene copolymer, wherein the propylene copolymer comprises from 94 to 99 wt. % of propylene and from 2.5 to 4.5 wt. % of a 1-butene comonomer, and wherein the propylene copolymer is at least partially crystallized in a beta-modification.

2. The propylene copolymer of claim 1 , wherein the propylene copolymer is a random copolymer.

3. The propylene copolymer of any one of claims 1 or 2 , wherein the amount of the propylene copolymer crystallized in the beta-modification is at least 50%, as determined by DSC using second heat.

4. The propylene copolymer of claim 1 , wherein the propylene copolymer has a flexural modulus of from about 1100 to about 1400 MPa.

5. The propylene copolymer of claim 1 , wherein the 1-butene comonomer is the only comonomer present in the propylene copolymer.

6. The propylene copolymer of claim 1 , further comprising a beta-nucleating agent.

7. The propylene copolymer of claim 6 , wherein the beta-nucleating agent is selected from the group consisting of N,N′-dicyclohexyl-2,6-naphthalene dicarboxamide, 5,12-dihydro-quino(2,3-b)acridine-7,14-dione, quino(2,3-b)acridine-6,7,13,14(5H,12H)-tetrone, salts of dicarboxylic acids with at least 7 carbon atoms with metals of group II of the periodic table, and mixtures thereof.

8. The propylene copolymer of claim 1 , wherein the propylene copolymer has a crack growth of from about 800 to about 1400 hours, as measured by FNCTNM5.

9. A molded article comprising the propylene copolymer of claim 1 .

10. The molded article of claim 9 , wherein the molded article is selected from pipes, couplers and articles required for pipe connections.

11. A method for preparing molded articles, the method comprising providing the propylene copolymer of claim 1 and molding the propylene copolymer into a molded article.

12. The method of claim 11 , wherein the molded article is selected from pipes, couplers and articles required for pipe connections.