Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2000-07-27
2002-06-11
Nutter, Nathan M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S240000
Reexamination Certificate
active
06403719
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a flexible resin composition which can provide molded products well-balanced among flexibility, heat resistance and compression set and having improved scratch resistance and transparency and which exhibits such high flowability as to cause excellent moldability. The present invention also relates to uses of the flexible resin composition.
BACKGROUND OF THE INVENTION
Because of its excellent scratch resistance, transparency and heat resistance, a polypropylene resin is widely employed for films, sheets, tubes and packing. The polypropylene resin now employed are excellent in scratch resistance, transparency and heat resistance but are not satisfactory in flexibility and compression set (CS), so that various methods to improve these properties have been studied.
For example, blending of the polypropylene resin with various elastomers (e.g., an ethylene/propylene copolymer rubber and an ethylene/1-butene copolymer rubber) to impart flexibility to the resin has been proposed.
Blending of the polypropylene resin with the conventional ethylene elastomers, however, has a problem in that the heat resistance and compression set are markedly lowered though the flexibility is improved.
Accordingly, there has been heretofore desired development of a polypropylene resin composition which can provide molded products well-balanced among flexibility, heat resistance and compression set and having improved scratch resistance and transparency and which exhibits high flowability favorable for various molding.
OBJECT OF THE INVENTION
The present invention is intended to solve such a problem associated with prior art as described above, and it is an object of the invention to provide a polypropylene resin-containing flexible resin composition which can provide molded products well-balanced among flexibility, heat resistance and compression set (CS) and having improved scratch resistance and transparency and which exhibits such high flowability as to cause excellent moldability.
SUMMARY OF THE INVENTION
The flexible resin composition according to the invention is a composition comprising:
(A) 100 parts by weight of a long-chain branched ethylene/&agr;-olefin random copolymer comprising ethylene and an &agr;-olefin of 3 to 20 carbon atoms, and
(B) 2 to 200 parts by weight of a polypropylene resin; the ethylene/&agr;-olefin random copolymer (A) having:
(i) a density of not more than 0.900 g/cm
3
,
(ii) an intrinsic viscosity (&eegr;) as measured in decalin at 135° C. of in the range of 0.3 to 3.0 dl/g,
(iii) a glass transition temperature (Tg) of not higher than −50° C.,
(iv) a crystallinity as measured by X-ray diffractometry of less than 40%,
(v) a molecular weight distribution (Mw/Mn) as determined by GPC of not more than 3.0,
(vi) a B value as determined by the
13
C-NMR spectrum and the following formula of in the range of 0.9 to 1.4,
B=P
OE
/(2P
O
.P
E
)
wherein P
E
and P
O
are a molar fraction of an ethylene component and a molar fraction of an &agr;-olefin component, respectively, contained in the ethylene/&agr;-olefin random copolymer (A) and P
OE
is a proportion of the number of ethylene/&agr;-olefin alternating sequences to the number of all dyad sequences, and
(vii) a ratio (g&eegr;* value, (&eegr;)/(&eegr;)blank) of the intrinsic viscosity (&eegr;) that is measured as the property (ii) to the intrinsic viscosity (&eegr;)blank of a linear ethylene/propylene copolymer having a weight average molecular weight (measured by a light scattering method) identical with that of the copolymer (A) and having an ethylene content of 70% by mol of in the range of 0.2 to 0.95; and
the polypropylene resin (B) having:
(i) an MFR (ASTM D 1238, 230° C., load: 2.16 kg) of in the range of 1 to 150 g/10 min, and
(ii) an initial flexural modulus (ASTM D 790) of not more than 1500 MPa.
It is most preferable that the polypropylene resin (B) is contained in an amount of 2 to 65 parts by weight based on 100 parts by weight of the ethylene/&agr;-olefin random copolymer (A).
The ethylene/&agr;-olefin random copolymer (A) preferably is an ethylene/&agr;-olefin random copolymer obtained by random copolymerizing ethylene and an &agr;-olefin of 3 to 20 carbon atoms in the presence of a metallocene catalyst containing a metallocene compound represented by the following formula (I):
wherein M is a transition metal of Group IVB of the periodic table,
R
1
is a hydrocarbon group of 1 to 6 carbon atoms,
R
2
, R
4
, R
5
and R
6
are the same or different and are each a hydrogen atom, a halogen atom or a hydrocarbon group of 1 to 6 carbon atoms,
R
3
is an aryl group of 6 to 16 carbon atoms, which may be substituted with a halogen atom, a hydrocarbon group of 1 to 20 carbon atoms or an organosilyl group,
X
1
and X
2
are each a hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 20 carbon atoms, a halogenated hydrocarbon group of 1 to 20 carbon atoms, an oxygen-containing group or a sulfur-containing group, and
Y is a divalent hydrocarbon group of 1 to 20 carbon atoms, a divalent halogenated hydrocarbon group of 1 to 20 carbon atoms, a divalent silicon-containing group, a divalent germanium-containing group, —O—, —CO—, —S—, —SO—, —SO
2
—, —NR
7
—, —P(R
7
)—, —P(O)(R
7
)—, —BR
7
— or —AlR
7
— (where R
7
is a hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 20 carbon atoms or a halogenated hydrocarbon group of 1 to 20 carbon atoms).
The injection molding resin composition, the extrusion molding resin composition and the compression molding resin composition according to the invention comprise the above-described flexible resin composition of the invention.
The flexible resin molded product according to the invention comprises the above-described flexible resin composition of the invention. This molded product may be a flexible resin sheet.
DETAILED DESCRIPTION OF THE INVENTION
The flexible resin composition according to the invention and uses thereof are described in detail hereinafter.
The flexible resin composition of the invention comprises a long-chain branched ethylene/&agr;-olefin random copolymer (A) and a polypropylene resin (B) in a specific ratio.
Ethylene/&agr;-olefin Random Copolymer (A)
The ethylene/&agr;-olefin random copolymer (A) for use in the invention is a long-chain branched ethylene/&agr;-olefin random copolymer comprising ethylene and an &agr;-olefin of 3 to 20 carbon atoms.
Examples of the &agr;-olefins of 3 to 20 carbon atoms include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene, 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-octadecene, 1-nonadecene, 1-eicosene, 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl-1-hexene, 9-methyl-1-decene, 11-methyl-1-dodecene, 12-ethyl-1-tetradecene and mixtures thereof.
The ethylene/&agr;-olefin random copolymer (A). for use in the invention has a density of not more than 0.900 g/cm
3
, preferably not more than 0.895 g/cm
3
, more preferably 0.840 to 0.890 g/cm
3
.
The ethylene/&agr;-olefin random copolymer (A) has an intrinsic viscosity (&eegr;), as measured in decalin at 135° C., of 0.3 to 3.0 dl/g, preferably 0.5 to 2.0 dl/g. The ethylene/&agr;-olefin random copolymer (A) having an intrinsic viscosity in the above range has good blendability with the polypropylene resin (B) . When this ethylene/&agr;-olefin random copolymer (A) is used, a polypropylene resin-containing flexible resin composition having high flowability and excellent moldability can be obtained.
The ethylene/&agr;-olefin random copolymer (A) has a glass transition temperature (Tg), as determined by DSC (differential scanning calorimeter), of not higher than −50° C., preferably not higher than −55° C., more preferably not higher than −57° C., particularly preferably −59° C. to −80° C.
The ethylene/&agr;-olefin random copolymer (A) has a crystallinity, as measured by X-ray diff
Tanaka Yasuo
Yasaka Naoto
Birch & Stewart Kolasch & Birch, LLP
Mitsui Chemicals Inc.
Nutter Nathan M.
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