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
2001-08-10
2004-03-02
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...
C525S206000, C525S207000, C525S208000, C525S220000, C525S221000, C525S222000, C525S223000, C525S225000, C525S226000, C525S227000, C525S228000, C525S229000, C525S231000
Reexamination Certificate
active
06699934
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a resin composition and a film thereof, which is low in glossiness, low in transparency, superior in tear strength, of pliable silk cloth-like feel, and low in loudness when crumpled by hands.
BACKGROUND OF THE INVENTION
Many of polyethylene films used as materials for packaging have high glossiness to obtain a superior appearance, high transparency to make packaged goods visible, as well as physical properties such as superior tear strength.
However, depending upon application purposes, the glossiness and high-transparency are not required. When used for the packaging of sanitary goods such as tissue paper, diaper paper and other goods, such as disposable rain wears and medical sheets, and polyethylene gloves used in places such as kitchens, factories, food stores, hotels' and hospitals, a polyethylene film is desired to be superior in tear strength, and in addition to, low glossiness, low transparency, a pliable silk cloth-like feel, and low loudness when crumpled by hand.
With respect to resin compositions and films with which the present invention is concerned, JP-A 61-106645 discloses a film of a mixture of ethylene-vinyl acetate copolymer and polyethylene; JP-A 2-4846 discloses a film of a mixture of ethylene-(meth)acrylate copolymer and polyethylene; JP-A 7-292174 discloses a resin composition comprising ethylene-1-hexene copolymer obtained by using a metallocene catalyst and ethylene-vinyl acetate copolymer, and a film of said resin composition; and JP-A 8-283480 discloses a resin composition comprising ethylene copolymer obtained using a metallocene catalyst, ethylene-vinyl ester copolymer and an anti-blocking agent.
However, the films disclosed in JP-A 61-106645 and JP-A 2-4846 are not satisfactory with respect to the low-glossiness, low-transparency and tear strength, and the films of the resin compositions disclosed in JP-A 7-292174 and JP-A 8-283480 are too transparent.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a film, which is low in glossiness, low in transparency, superior in tear strength, pliable with a silk cloth-like feel, and low in loudness when crumpled by hands.
Another object of the present invention is to provide a resin composition capable of providing such a film.
The present invention provides a resin composition comprising;
(A) from 1 to 99% by weight of a copolymer, which comprises an ethylene unit and an a-olefin unit of 3 to 12 carbon atoms and,
(B) from 99 to 1% by weight of a copolymer, which comprises an ethylene unit and a unit of a compound having a carbon-carbon double bond and an oxygen atom, provided that the sum of the copolymer (A) and the copolymer
(C) is 100% by weight, wherein the copolymer (A) satisfies the following requirements (A-1) to (A-4), and the copolymer (B) satisfies the following requirements (B-1) and (B-2),
(A-1): a melt flow rate (MFR) is from 0.1 to 50 g/10 min,
(A-2): a density (d) is from 880 to 935 Kg/m
3
,
(A-3): a composition distribution variation coefficient (Cx) represented by the following equation (1) is not more than 0.5,
Cx=&sgr;/SCBave
(1)
wherein &sgr; is a standard deviation of composition distribution, and SCBave is an average branching degree,
(A-4): a content (a) of cold xylene-soluble portion in terms of % by weight based on the weight of the copolymer (A) and the density (d) satisfy the following inequality (2),
a
<4.8×10
−5
×(950
−d
)
3
+10
−6
×(950
−d
)
4
+1 (2).
(B-1): a melt flow rate (MFR) is from 0.01 to 50 g/10 min, and
(B-2): a content (b) of a unit of a compound having a carbon-carbon double bond and an oxygen atom in terms of % by weight based on the weight of the sum of the ethylene unit and the unit of a compound having a carbon-carbon double bond and an oxygen atom, and a content (WB) of the copolymer (B) in the resin composition in terms of % by weight based on the weight of the sum of the copolymer (A) and the copolymer (B) satisfy the following inequality (3),
50
>b
>0.2
×WB
+10 (3).
The present invention also provides a film comprising the above-mentioned resin composition.
DETAILED DESCRIPTION OF THE INVENTION
The copolymer (A) used in the present invention, which is, according to circumstances, referred to as “component (A)”, can be obtained by copolymerizing ethylene and at least one &agr;-olefin of 3 to 12 carbon atoms. The above mentioned “ethylene unit” means a structure unit derived from ethylene. Similarly, the above-mentioned “&agr;-olefin unit of 3 to 12 carbon atoms” means a structure unit derived from said a-olefin.
Examples of the above-mentioned &agr;-olefin are propylene, butene-1, pentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, dodecene-1, 4-methyl-pentene-1, 4-methyl-hexene-1 and vinylcyclohexane. Of these, preferred are butene-1, hexene-1 and octene-1, and more preferred is hexene-1.
Examples of the copolymer (A) are ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-hexene-1 copolymer and ethylene-octene-1 copolymer. Of these, ethylene-hexene-1 copolymer is preferred.
A melt flow rate (MFR) of the copolymer (A) is from 0.1 to 50 g/10 min, preferably from 0.5 to 20 g/10 min, more preferably from 0.5 to 10 g/10 min, much more preferably from 2 to 5 g/10 min. When the melt flow rate is less than 0.1 g/10 min, the film from the obtained resin composition may be too heavy. When it exceeds 50 g/10 min, tear strength of the film obtained may decrease.
A density (d) of the copolymer (A) is from 880 to 935 Kg/m
3
, preferably from 890 to 930 Kg/m
3
, more preferably from 910 to 930 Kg/m
3
. When the density is less than 880 Kg/m
3
, rigidity of the film obtained may decrease, and as a result, the film may become unsuitable for packaging film from a viewpoint of a handling facility. When it exceeds 935 Kg/m
3
, impact strength of the film obtained may decrease.
A composition distribution variation coefficient (Cx) represented by the above-mentioned equation (1) is not more than 0.5, preferably from 0.2 to 0.4. When the composition distribution variation coefficient exceeds 0.5, glossiness of the film in accordance with the present invention may increase, or tear strength and anti-blocking property thereof may deteriorate.
The composition distribution variation coefficient is a measure showing a distribution degree of the monomer unit in the copolymer (A). The smaller the Cx value, the narrower the composition distribution, in other words, the ethylene unit and the &agr;-olefin unit are more uniformly distributed in the copolymer (A). A measurement method of the Cx value is mentioned hereinafter.
A content (a) (% by weight) of cold xylene-soluble portion and a density (d) of the copolymer (A) satisfy the above-mentioned inequality (2). A copolymer (A) satisfying the following inequality (4) is preferred, and a copolymer (A) satisfying the following inequality (5) is more preferred.
a
<4.8×10
−5
×(950
−d
)
3
+10
−6
×(950
−d
)
4
(4)
a
<4.8×10
−5
×(950
−d
)
3
(5)
When the copolymer (A) does not satisfy the above inequality (2), tear strength of the film in accordance with the present invention may decrease, glossiness thereof may increase or anti-blocking property thereof may deteriorate.
A process for producing the copolymer (A) is not limited. The copolymer (A) can be produced according to a conventional process using a conventional catalyst. As the conventional catalyst, those containing a transition metal compound be used. A preferred conventional catalyst is that which contains a transitional metal compound having a cyclopentadiene type anion skeleton-carrying group, namely, a so-called metallocene compound. A more preferred metallocene compound is represented by the following formula,
ML
c
X
n−o
wherein M is a transition metal atom belonging to the group 4 or-the lanthanide series of the periodic table, L is a cyclopentadie
Chikanari Kenzo
Koyama Satoru
Nakanishi Daigo
Nutter Nathan M.
Sumitomo Chemical Company Limited
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