Stiff blown film

Patent metadata

Field	Value
Publication number	US-12534553-B2
Application number	US-202117797183-A
Country	US
Kind code	B2
Filing date	Mar 17, 2021
Priority date	Mar 24, 2020
Publication date	Jan 27, 2026
Grant date	Jan 27, 2026

Abstract

Blown films, especially monolayer blown films, of high stiffness, the blown films comprising at least 95.0 wt % of a specific propylene-1-butene random copolymer.

First claim

The invention claimed is:

1 . Blown film comprising at least 95.0 wt % of a propylene-1-butene random copolymer, the propylene-1-butene random copolymer having
a) a melt flow rate (MFR2; 230° C./2.16 kg; measured according to ISO 1133) in the range of from 0.5 to below 4.0 g/10 min, b) a 1-butene content in the range of from 2.0 to 15.0 wt % based on the total weight of the propylene-1-butene random copolymer and c) a xylene cold soluble (XCS) fraction measured according to ISO 16152 at 25° C. in the range of from 0.10 to 2.80 wt %, d) a molecular weight distribution (Mw/Mn) of 2.0 to less than 4.5, e) a double melting peak (Tm 1 and Tm 2 ) in differential scanning calorimetry, wherein Tm 1 of the propylene-1-butene copolymer is in the range of from 125 to 145° C., and wherein Tm 2 of the propylene-1-butene copolymer is in the range of from 100 to 140° C., and f) wherein said copolymer is prepared by using a single site catalyst, said blown film having i) a Tensile modulus, in machine and transverse direction according to ISO 527-3 at 23° C. measured on 50 μm blown films, in the range of from 700 to 1800 MPa.

2 . Blown film according to claim 1 , wherein the propylene-1-butene random copolymer contains an alpha-nucleating agent in an amount of from 100 to 2,000 ppm based on the total weight of the copolymer.

3 . Blown film according to claim 1 , wherein said propylene-1-butene random copolymer comprises:
30.0 to 70.0 wt % based on the total weight of the propylene-1-butene random copolymer of a propylene-1-butene copolymer (A) having an MFR2 of 0.5 to 20.0 g/10 min and a 1-butene content of 2.0 to 10.0 wt % based on the total weight of the propylene-1-butene random copolymer (A); and 70.0 to 30.0 wt % based on the total weight of the propylene-1-butene random copolymer of a propylene butene copolymer (B) having an MFR2 of 0.5 to 20.0 g/10 min and a 1-butene content of 3.5 to 20.0 wt % based on the total weight of the propylene-1-butene copolymer (B); wherein copolymers (A) and (B) are different and the amount of (A) and (B) sums up to 100.0%.

4 . Blown film according to claim 1 , wherein the propylene-1-butene random copolymer has a crystallization temperature T c as determined by DSC (differential scanning calorimetry) according to ISO 11357 in the range of from 85° C. to 115° C., and wherein the difference between melting temperature Tm 1 and crystallization temperature Tc, (Tm 1 -T c ), is in the range of from 25° C. to 42° C.

5 . Blown film according to claim 1 , wherein the propylene-1-butene random copolymer has a flexural modulus, determined according to ISO 178, in the range of from 700 to 1800 MPa.

6 . Blown film according to claim 1 , wherein the propylene-1-butene random copolymer has a Charpy notched impact strength at 23° C., determined according to ISO 179 1eA, in the range of from 2.0 kJ/m 2 to 10.0 kJ/m 2 and/or
a haze measured according to ASTM D1033 on a 1.0 mm thick plaque in the range of from 5.0 to below 70.0%.

7 . Blown film according to claim 1 , wherein the propylene-1-butene random copolymer has an amount of hexane hot solubles (C6 FDA) measured on a 100 μm thick blown film according to FDA 177.1520 in the range of from 0.1 to less than 2.0 wt %.

8 . Blown film according to claim 6 , wherein the film has a haze measured according to ASTM D1033 on a 50 μm blown film in the range of from 0.1 to below 12.0%.

9 . Blown film according to claim 1 , wherein the film has an optomechanical ability (OMA) determined on a 50 μm blown film according the formula given below:

OMA
=

Tensile
⁢

Modulus
⁢

(
MD
)

[
MPa
]

*

DDI
⁡
(
g
)

Haze
⁢

(

50
⁢

µm

)

[
%
]

of at least 5000 [MPa*g/%] up to 45000 [MPa*g/%], wherein the Tensile Modulus in machine direction is measured according to ISO 527-3 at 23° C. on 50 μm blown films, DDI is the dart-drop impact strength determined according to ASTM D1709, method A on a 50 μm blown film and haze is measured according to ASTM D1033 on a 50 μm blown film.

10 . Blown film according to claim 1 , wherein the film has a sealing initiation temperature (SIT), measured on a 50 μm blown film, in the range of 105 to 135° C.

11 . Blown film according to claim 2 , wherein the film has a hot-tack force determined on 50 μm blown film in the range of from 2.0 to 6.0 N.

12 . Blown film according to claim 6 , wherein the film has a haze after sterilization (steam sterilization at 121° C. for 30 min) determined according to ASTM D 1003-00 measured on a 50 μm blown film in the range of from 0.5 to below 12.0%.

13 . Blown film according to claim 10 , wherein the film has a clarity (determined according to ASTM D1003-00 on blow films with a thickness of 50 μm) of at least 90.0%, and a clarity (determined according to ASTM D1003-00 on blown films with a thickness of 50 μm) after sterilization (steam sterilization at 121° C. for 30 min) of at least 90.0%.

14 . Blown film according to claim 1 , wherein the film is a monolayer film.

15 . The blown film of claim 1 , wherein the propylene-1-butene random copolymer exhibits a double melting peak (Tm 1 and Tm 2 ) in differential scanning calorimetry, wherein Tm 1 of the propylene-1-butene copolymer is in the range of from 130 to 145° C., and wherein Tm 2 of the propylene-1-butene copolymer is in the range of from 105 to 138° C.

16 . The blown film of claim 1 , wherein the propylene-1-butene random copolymer exhibits a double melting peak (Tm 1 and Tm 2 ) in differential scanning calorimetry, wherein Tm 1 of the propylene-1-butene copolymer is in the range of from 135 to 145° C., and wherein Tm 2 of the propylene-1-butene copolymer is in the range of from 107 to 135° C.

17 . Blown film according to claim 1 , wherein the propylene-1-butene random copolymer has a crystallization temperature T c as determined by DSC (differential scanning calorimetry) according to ISO 11357 in the range of from 90° C. to 112° C., and wherein the difference between melting temperature Tm 1 and crystallization temperature T c , (Tm 1 -T c ), is in the range of from 28° C. to 40° C.

18 . Blown film according to claim 1 , wherein the propylene-1-butene random copolymer has a flexural modulus, determined according to ISO 178, in the range of from 800 to 1400 MPa.

19 . Blown film according to claim 1 , wherein the pr

Assignees

• Borealis Ag

Inventors

• Wang Jingbo
• Gahleitner Markus
• Bernreitner Klaus
• Leskinen Pauli
• Hoff Matthias

Classifications

• C08L2314/06

  Metallocene or single site catalysts · CPC title

• C08L2205/24

  Crystallisation aids · CPC title

• C08L2205/025

  containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure · CPC title

• C08L2203/162

  sealable films · CPC title

• C08J2323/14

  Copolymers of propene (C08J2323/16 takes precedence) · CPC title