Sumitomo Chemical Company, Limited

Eisuke Shiratani

Kazuki Wakamatsu

Seiichiro Ima

Hajime Sadatoshi

Takanori Kume

Haruo Hayashida

Shigeki Kishiro

Jiro Mori

Akihiro Ichige

Kouichi Yanase

Ikuo Yamamoto

Low temperature heat-sealable polypropylene-based film

Polypropylene random copolymer and film thereof

A polypropylene block copolymer obtained by producing an ethylene-propylene copolymer moiety as a component A having an ethylene content of 1.5 to 6.0% by weight in an amount of 40 to 85% by weight based on the total weight of components A and B in the absence of an inert solvent, substantially, in a first step, with a Ziegler-Natta catalyst, and then producing an ethylene-propylene copolymer moiety as a component B having an ethylene content of 7 to 17% by weight in an amount of 15 to 60% by weight based on an amount of the whole polymer in a gas phase in a second step, wherein an intrinsic viscosity (&lsqb;&eegr;&rsqb;B) of the component B is from 2.0 to 5.0 dl/g and the ratio of the intrinsic viscosity (&lsqb;&eegr;&rsqb;B) of the component B to an intrinsic viscosity (&lsqb;&eegr;&rsqb;A) of the component A is within the range of 0.5 to 1.8.

Propylene block copolymer

There is provided a self-tack wrapping film comprising a non-oriented multi-layer film of a chlorine-free resin, which is regulated in (a) tensile breaking elongation at a longitudinal direction, (b) ratio of a tensile breaking elongation at a transverse direction to the tensile breaking elongation at a longitudinal direction, (c) tensile breaking load at a longitudinal direction (LLD), (d) ratio of the tensile breaking load at a longitudinal direction to a tensile breaking load at a transverse direction, (e) tensile modulus at a longitudinal direction and that at a transverse direction, (f) tackiness, (g) heat resistant temperature and (h) respective thermal shrinkage percents at longitudinal and transverse directions, to a predetermined range, which wrapping film has improved tackiness, heat resistance, microwave oven suitability and 'saw blade' cutting characteristics, and appropriate flexibility.

Multi-layer self-tack wrapping film

A propylene block copolymer having a specified composition and consisting of a xylene soluble portion at 20.degree. C. in an amount of 5 wt % or more and a portion excluding the CXS portion, the melting temperature of the CXIS portion measured by a differential scanning caloriemeter being 130 to 155.degree. C., wherein the difference in transparency in terms of haze between prior to and posterior to the 1-hour treatment at 110.degree. C of a 150 .mu.m thick film obtained by forming said copolymer into a film by extrusion is 8% or less. According to the present invention, a block copolymer having a good transparency and improved impact resistance at a low temperature, and further exhibiting less bleeding at high-temperature heat treatment, can be provided.

A film containing a first layer containing a propylene-based block copolymer (a) obtainable by forming 40 to 85% by weight of a propylene-ethylene copolymer portion (A) having a content of repeating unit derived from ethylene of 1.5 to 6.0% by weight in a first step, and then forming 15 to 60% by weight of a propylene-ethylene copolymer portion (B) having a content of repeating unit derived from ethylene of 7 to 17% by weight in a second step, the intrinsic viscosity of portion (B) being 2 to 5 dl/g, and the ratio of the intrinsic viscosity of portion (B) to the intrinsic viscosity of portion (A) being 0.5 to 1.8, and a second layer containing a polyethylene type resin (b) laminated on at least one surface of the first layer, has a good balance between heat resistance, flexibility, mechanical strength, transparency, cuttability, original-shape resuming property and other desirable properties, and is suitably used for wrapping materials such as foods.

Multi-layer stretch wrapping film

A film having a low dependency of film transparency on film-forming conditions and film thickness, and having superior transparency and rigidity without compromising the original properties of polypropylene film. The film is produced from a polypropylene prepared from a propylene polymer having (1) a stereoirregularity index mmrr/mmmm of a part insoluble in xylene at 20.degree. C. within the range of 0.0095 to 0.0200; (2) a melting temperature within the range of 145.degree. to 160.degree. C.; (3) a part soluble in xylene at 20.degree. C. of 3.5% by weight or less, the polypropylene having: (4) a melt flow rate at 230.degree. C. within the range of 5 to 15 g/10 min.; and (5) a swelling ratio within the range of 1.20 to 1.35.

Polypropylene film

A polypropylene composition comprising a melt-kneaded polyprolylene composition obtained, using Zieglar-Natta catalyst, by polymerizing a monomer comprising propylene to form a polymer comprising polypropylene (component A) in amount of from 60 to 80% by weight to the total polymer amount in substantially the absence of an inert solvent in a 1st step and then polymerizing a mixture of ethylene content of from 20 to 50% by weight (component B) in a vapor phase to form an ethylene-propylene copolymer (component B) in amount of from 20 to 40% by weight to the total polymer amount in a 2nd step, said polypropylene composition being such that the intrinsic viscosity of component B ([.eta.]B) is at least 2.0 dl/g and the ratio ([.eta.]B/[.eta.]A) of the intrinsic viscosity of the component B to the intrinsic viscosity of the component A ([.eta.]A) is 1.8 or less and the melt flow rate of the polypropylene composition after melt-kneaded being 0.5 to 10 g/10 minutes.

Polypropylene composition and the film thereof

A polypropylene composition comprising 100 parts by weight of a crystalline propylene polymer having a melt flow rate of at least 3.0 g/10 minutes and a molecular weight distribution of less than 5.0 and from 0.01 to less than 4.0 parts by weight of a crystalline ethylene polymer having a melt flow rate of from 0.5 to 300 g/10 minutes, a density of at least 0.910 g/cm.sup.3, and a crystallization temperature of at least 85.degree. C. and which is at least 1.degree. C. higher than the crystallization temperature of the crystalline propylene polymer.

Growing community of inventors

Ichihara, Japan

Eisuke Shiratani