Transparant polyolefin compositions

Abstract

A polyolefin composition having good transparency and mechanical properties comprising, all percent amounts being by weight: A) from 70 to 98% of a propylene homopolymer or copolymer having haze of 25% or less and melting temperature of 130 C. or higher; and B) from 2 to 30% of a butene-1 copolymer containing from 0.5 to 30% of one or more comonomer(s).

Claims

1. A polyolefin composition comprising: A) 75-85% by weight of a propylene homopolymer or copolymer having a haze value of 25% or less, a polydispersity index from 6 to 7.3, a flexural modulus value higher than 600 MPa, and melting temperature of 140 C. or higher; and B) 15-25% by weight of a butene-1 copolymer containing from 1.5 to 5.5% by weight of ethylene, the composition having: (i) a haze value of equal to or lower than 25%, measured on 1 mm thick specimens, (ii) a melt flow rate from 1 to 100 g/10 min, measured at 230 C. with a load of 2.16 kg, and (iii) a flexural modulus value in a range of between 830 and 1210 MPa.

2. The polyolefin composition of claim 1, wherein A) contains a clarifying agent selected from the group consisting of acetals of sorbitols, acetals of xylitols, and phosphate ester salts.

3. The polyolefin composition of claim 1, wherein A) is a propylene homopolymer.

4. The polyolefin composition of claim 1, wherein A) is a propylene copolymer containing from 0.5 to 15% by weight of comonomer(s).

5. The polyolefin composition of claim 1, wherein A) is a propylene copolymer containing one or more comonomers selected from ethylene and CH.sub.2=CHR -olefins and R is a C.sub.2C.sub.8 alkyl radical.

6. The polyolefin composition of claim 1, wherein A) comprises a xylene insoluble fraction equal to or greater than 85% by weight.

7. An injection molded article comprising the polyolefin composition of claim 1.

Description

EXAMPLE 1 AND COMPARISON EXAMPLE 1

(1) Preparation of the Polyolefin Compositions and Films

(2) The polyolefin compositions used in the examples are blends made of the above described PP-1 and PP-2 polymers as component (A), and of the above described PB-1 copolymer and EPR as component (B) and comparison component (B) respectively. The blends are made using a Werner extruder, with a melt temperature of 215 C. The composition of the blends is reported in Table 1 below.

(3) TABLE-US-00001 TABLE 1 Example No. 1 Comp. 1 PP-1 (weight %) 85 PP-2 (weight %) 75 PB-1 (weight %) 15 EPR (weight %) 25 Note: Comp. = Comparison.

(4) The properties are listed in Table 2 below.

(5) TABLE-US-00002 TABLE 2 Example No. 1 Comp. 1 MFR g/10 min. 9.5 11.2 PI 6.8 5.7 HAZE on plaque 1 mm % 23.6 33.6 Izod 0 C. kJ/m.sup.2 2.2 8.6 Izod 23 C. kJ/m.sup.2 3.8 33.9 MEF MPa 1210 830 MET MPa 1380 920 Tensile Strength at yield MPa 31.4 22.6 Elongation at yield % 11.5 16.5 Tensile Strength at break MPa 19.8 19.9 Elongation at break % 800 780 HDT C. 89.8 76.4