Stock material or miscellaneous articles – Composite – Of addition polymer from unsaturated monomers
Reexamination Certificate
2001-03-21
2002-09-24
Mullis, Jeffrey (Department: 1711)
Stock material or miscellaneous articles
Composite
Of addition polymer from unsaturated monomers
C525S193000, C525S240000, C525S241000
Reexamination Certificate
active
06455170
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a modified polypropylene composition and a laminate using the composition. More particularly, the invention relates to a modified polypropylene composition for forming a laminate, which is capable of preventing lowering of interlaminar strength of a laminate using the composition even if the laminate such as a multi-layer film or a multi-layer bottle is subjected to a heat treatment at a high temperature such as a temperature of 80 to 125° C., and also relates to a laminate using, the composition and having excellent interlaminar strength.
BACKGROUND OF THE INVENTION
A polypropylene resin is excellent in mechanical strength, rigidity, heat resistance, chemical resistance, oil resistance, transparency and impact resistance at low temperatures. By taking advantage of these properties, the polypropylene resin is widely used for packaging/covering materials, such as films, sheets and bottles, or decorative materials such as wall paper.
The polypropylene resin, however, has high permeability of gas such as oxygen, so that this resin cannot be used for packaging materials requiring high gas barrier properties, such as packaging materials for foods, chemicals and cosmetics. To enhance the gas barrier properties of the polypropylene resin, it has been proposed to laminate the polypropylene resin onto a resin having higher gas barrier properties than the polypropylene resin, e.g., an ethylene vinyl acetate copolymer saponification product. In this case, the adhesion between the polypropylene and the olefin/vinyl acetate copolymer saponification product (referred to as “EVOH” hereinafter) is extremely low, so that an adhesive resin, such as an ionomer, an ethylene/vinyl acetate copolymer or a carboxylic acid-graft modification product, is co-extruded to obtain a multi-layer structure.
However, if a bag of this multi-layer structure is filled with contents at a high temperature or subjected to a heat treatment after filling, it is expanded or shrunk, and consequently the EVOH layer is separated from the adhesive resin layer when it is subjected to fabricating, falling or bending. As a result, the manufactured product sometimes has disadvantages in quality (e.g., strength) and appearance. In addition, because of separation between the EVOH layer and the adhesive resin layer, the EVOH layer is liable to be cracked, and as a result the gas barrier properties may be lowered. Also in case of the decorative materials such as wall paper, separation between the substrate and the adhesive resin layer may take place under circumstances where heating and cooling are repeated, resulting in bad appearance.
Accordingly, there has been desired development of modified polypropylene composition for forming a laminate, which is capable of preventing lowering of interlaminar strength of a laminate using the composition even if the laminate is subjected to a heat treatment at a high temperature such as a temperature of 80 to 125° C., and a laminate using the composition and having excellent interlaminar strength.
OBJECT OF THE INVENTION
The present invention is intended to solve such problems associated with the prior art as described above, and it is an object of the invention to provide a modified polypropylene composition for forming a laminate, which is capable of preventing lowering of interlaminar strength of a laminate using the composition even if the laminate is subjected to a heat treatment at a high temperature such as a temperature of 80 to 125° C. It is another object of the invention to provide a laminate using the composition and having excellent interlaminar strength.
SUMMARY OF THE INVENTION
The modified polypropylene composition according to the invention is a composition comprising:
(A) modified polypropylene having been partially or wholly graft modified with an unsaturated carboxylic acid or its derivative, in an amount of 40 to 92% by weight,
(B) an amorphous or low-crystalline ethylene/&agr;-olefin copolymer having a melt flow rate (MFR, ASTM D 1238, 230° C., load of 2.16 kg) of 0.01 to 10 g/10 min and a density (ASTM D 1505) of not more than 0.900 g/cm
3
, in an amount of 5 to 30% by weight, and
(C) a styrene elastomer in an amount of 3 to 30% by weight,
wherein the modified polypropylene (A) is a graft modification product (A1) of a propylene homopolymer and/or a graft modification product (A2) of a propylene/&agr;-olefin random copolymer containing constituent units derived from an &agr;-olefin other than propylene in amounts of not more than 10% by mol based on 100% by mol of the total of constituent units derived from propylene and constituent units derived from an &agr;-olefin other than propylene.
In the modified polypropylene (A), the degree of graft modification with the unsaturated carboxylic acid or its derivative is desired to be in the range of 0.001 to 5% by weight based on 100% by weight of polypropylene before the graft modification.
The laminate according to the invention has a two-layer or three-layer structure comprising a composition layer formed from the modified polypropylene composition of the invention and a resin layer provided on one or both surfaces of the composition layer, or has a structure of three or more layers including said two-layer or three-layer structure.
The resin for forming the resin layer is preferably a homopolymer of a monomer having a polar group or a copolymer of a non-polar monomer and a polar monomer.
DETAILED DESCRIPTION OF THE INVENTION
The modified polypropylene composition according to the invention and the laminate using the composition are described in detail hereinafter.
The modified polypropylene composition of the invention comprises modified polypropylene (A), an ethylene/&agr;-olefin copolymer (B) and a styrene elastomer (C).
Modified Polypropylene (A)
The modified polypropylene (A) for use in the invention is a graft modification product (A1) of a propylene homopolymer and/or a graft modification product (A2) of a propylene/&agr;-olefin random copolymer.
The graft modification product (A1) and the propylene homopolymer before the graft modification desirably have a melt flow rate (MFR, ASTM D 1238, 230° C., load of 2.16 kg) of 0.1 to 800 g/10 min, preferably 0.5 to 100 g/10 min, more preferably 1.0 to 20 g/10 min.
The propylene/&agr;-olefin random copolymer to be graft modified to prepare the graft modification product (A2) is a propylene/&agr;-olefin random copolymer obtained by copolymerizing propylene and an (&agr;olefin other than propylene, preferably an &agr;-olefin of 2 or 4 to 20 carbon atoms.
Examples of the &agr;-olefins of 2 or 4 to 20 carbon atoms to be copolymerized with propylene include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-nonadecene, 1-eicosene and 4-methyl-1-pentene. These &agr;-olefins are used singly or in combination of two or more kinds.
In the propylene/&agr;-olefin random copolymer, constituent units derived from propylene are contained in amounts of not less than 90% by mol, usually 90 to 99% by mol, preferably not less than 95% by mol, and constituent units derived from an &agr;-olefin of 2 or 4 to 20 carbon atoms are contained in amounts of not more than 10% by mol, usually 1 to 10% by mol. preferably not more than 5% by mol.
Composition of the propylene/&agr;-olefin random copolymer is determined by measuring a
13
C-NMR spectrum of a sample solution obtained by homogeneously dissolving about 200 mg of the propylene/&agr;-olefin random copolymer in 1 ml of hexachlorobutadiene in a sample tube of usually 10 mm diameter, under the measuring conditions of a measuring temperature of 120° C., a measuring frequency of 25.05 MHz, a spectral width of 1500 Hz, a pulse repetition time of 4.2 sec and a pulse width of 6 &mgr;sec.
The graft modification product (A2) and the propylene/&agr;-olefin random copolymer before the graft modification desirably have a melt flow rate (MFR, ASTM D 1238, 230° C., load of 2.16 kg) of 0.1 to 100 g/10 min, p
Kawachi Hideshi
Sawada Yuji
Yasui Shigeyuki
Birch & Stewart Kolasch & Birch, LLP
Mitsui Chemicals Inc.
Mullis Jeffrey
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