Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
2001-09-26
2003-07-08
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S499000
Reexamination Certificate
active
06590021
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyolefin resin composition and a film comprising the same, which film is superior in transparency, a see through property, anti-blocking property, sliding property, anti-scratching property, fabrication and visual appearance (flickering of films), and which film is well-balanced in these properties.
BACKGROUND OF THE INVENTION
With respect to materials used for producing a film for wrapping use, it is required that (1) film formation property is good, and (2) a film-forming machine is hardly stained.
Further, with respect to the film, it is required that (1) an article wrapped is clearly visible (namely, the film is superior in its transparency), (2) its appearance is superior, (3) when a bag is formed from the film, the film is easily handled (namely, the film is superior in its fabrication), (4) when an article is packed in the bag (particularly when it is automatically packed), a mouth of the bag is easy to open (namely, the film is superior in its anti-blocking property and in its sliding property), and (5) when the film or the bag in which an article is packed is transported, any scratch is hardly produced by friction between the films or the bags (namely, the film is superior in its anti-scratching property).
Polyolefin resins such as ethylene-&agr;-olefin copolymers, which are suitably used as materials for producing a film for wrapping use, are used in combination with an additive such as an anti-blocking agent and a lublicant, thereby obtaining a film superior in its anti-blocking and sliding properties.
For example, JP-A 7-258478 discloses a polyolefin resin composition comprising (1) a polyolefin resin, (2) an anti-blocking agent of a substantially sphere form having an average particle diameter of from 1 to 10 &mgr;m, and (3) an additional anti-blocking agent, (a) which additional anti-blocking agent is obtained by pulverizing and calcining a natural mineral, (b) which has an average particle diameter of from 1 to 5 &mgr;m, and (c) which comprises from 10 to 40% by weight of particles having a particle diameter of not less than 1.5 times said average particle diameter.
Further, JP-A 8-92428 discloses a polyolefin resin composition comprising (1) 100 parts by weight of a polyolefin resin, and (2) 0.01 to 2.0 parts by weight of an anti-blocking agent, which anti-blocking agent has a particle diameter distribution showing not less than two maximum values, among which maximum values a difference between a maximum particle diameter and a minimum particle diameter is not less than 3.0 &mgr;m.
However, a film comprising the resin composition disclosed in JP-A 7-258478 has a problem that a see through property and flickering of films are remarkable because said resin composition has a bulky anti-blocking agent of not less than 1.0% by weight, which bulky anti-blocking agent has a particle diameter of not less than 22 &mgr;m in a volume particle diameter distribution.
Also, a film comprising the resin composition disclosed in JP-A8-92428 similarly has a problem that a see through property and flickering of films are not satisfactory because said resin composition has a bulky anti-blocking agent of not less than 1.0% by weight, which bulky anti-blocking agent has a particle diameter of not less than 22 &mgr;m in a volume particle diameter distribution.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a film, which film is superior in transparency, see through property, anti-blocking property, sliding property, anti-scratching property and fabrication, which film hardly has visually dazzling sense (namely, superior in appearance), and which film is well-balanced in these properties.
Another object of the present invention is to provide a polyolefin resin composition suitable for producing said film.
The present invention provides a polyolefin resin composition comprising:
(i) a polyolefin resin, and
(ii) an anti-blocking agent in an amount of from 500 to 15,000 ppm by weight based on the weight of the polyolefin resin, which anti-blocking agent is made of a natural mineral and has:
(a) a volume average particle diameter of from 1 to 5 &mgr;m.
(b) particles having a particle diameter of not less than 1.5 times the above-defined volume average particle diameter in an amount of from 30 to 40% by weight, and
(c) particles having a particle diameter exceeding 22 &mgr;m in an amount of less than 1.0% by weight,
provided that the above-defined % by weight is based on that the total weight of the anti-blocking agent made of a natural mineral is regarded as 100% by weight.
The present invention also provides a film comprising the above-defined polyolefin resin composition.
DETAILED DESCRIPTION OF THE INVENTION
The “polyolefin resin” used in the present invention means a thermoplastic resin comprising at least one kind of a C
2
to C
10
olefin polymerization unit (said “olefin polymerization unit” is hereinafter referred to simply as “olefin unit”), in an amount of from 50 to 100% by weight (a weight of the polyolefin resin is assigned to be 100% by weight).
Examples of the polyolefin resin are ethylene homopolymers; &agr;-olefin homopolymers; ethylene-&agr;-olefin copolymers; propylene-&agr;-olefin copolymers; ethylene-propylene-&agr;-olefin copolymers; copolymers of ethylene and poly-unsaturated compounds; and copolymers of ethylene, &agr;-olefins and poly-unsaturated compounds.
Examples of the above-mentioned &agr;-olefin are propylene, butene-1, pentene-1, 4-methyl-1-pentene, hexene-1, octene-1 and decene-1. Of these, preferred are propylene, butene-1, hexene-1 and octene-1, and more preferred are butene-1 and hexene-1.
Examples of the poly-unsaturated compounds are divinylbenzene, norbornadiene, dicyclopentadiene, 1, 5-hexadiene, 1, 7-octadiene, 1, 9-decadiene, vinylnorbornene, vinylcyclohexene and ethylidenenorbornene. Of these, preferred are divinylbenzene, norbornadiene and dicyclopentadiene.
Besides ethylene homopolymers, the above-mentioned &agr;-olefin homopolymers contains, for example, propylene homopolymers, butene-1 homopolymers and 4-methyl-pentene-1 homopolymers. Of these, preferred are ethylene homopolymers and propylene homopolymers.
Examples of the above-mentioned ethylene-&agr;-olefin copolymers are ethylene-propylene copolymers, ethylene-butene-1 copolymers, ethylene-4-methylpentene-1 copolymers, ethylene-hexene-1 copolymers, ethylene-octene-1 copolymers and ethylene-decene-1 copolymers. Of these, preferred are ethylene-butene-1 copolymers, ethylene-4-methylpentene-1 copolymers, ethylene-hexene-1 copolymers, ethylene-octene-1 copolymers and ethylene-butene-1 copolymers.
Examples of the above-mentioned propylene-&agr;-olefin copolymers are propylene-4-methylpentene-1 copolymers and propylene-butene-1 copolymers. Of these, preferred is a propylene-butene-1 copolymer.
Examples of the above-mentioned ethylene-propylene-&agr;-olefin copolymers are ethylene-propylene-butene-1 copolymers and ethylene-propylene-hexene-1 copolymers. Of these, preferred is an ethylene-propylene-butene-1 copolymer.
Examples of the above-mentioned ethylene-&agr;-olefin-poly-unsaturated compound copolymers are ethylene-propylene-divinylbenzene copolymers, ethylene-propylene-norbornadiene copolymers and ethylene-propylene-dicyclopentadiene copolymers. Of these, preferred is an ethylene-propylene-divinylbenzene copolymers.
A preferred polyolefin resin is the ethylene-&agr;-olefin copolymer. A content of an &agr;-olefin unit in the copolymer is preferably from 0.5 to 30% by weight, and more preferably from 1.0 to 20% by weight, based on 100% by weight of the sum of an ethylene unit content and an a-olefin unit content. A density (d) of the copolymer is preferably from 880 to 970 kg/m
3
, more preferably from 890 to 940 kg/m
3
, and much more preferably from 910 to 930 kg/M
3
. A melt flow rate (MFR) of the copolymer is preferably from 0.1 to 50 g/10 min., more preferably from 0.2 to 20 g/10 min., and much more preferably from 0.3 to 5.0 g/10 min. A cold xylene-soluble portion (CXS) of the copolymer is preferabl
Mitsuno Tadahiro
Shiraishi Hiroyuki
Niland Patrick D.
Sughrue & Mion, PLLC
Sumitomo Chemical Company Limited
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