Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
2002-01-24
2004-08-10
Tarazano, D. Lawrence (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S515000, C428S516000, C428S523000, C525S240000, C526S248000, C526S943000
Reexamination Certificate
active
06773808
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an adhesive film. The adhesive film in accordance with the present invention can be used particularly preferably (i) as a surface protecting film applied to a surface of articles such as synthetic resin boards, decorated plywood, metal plates and coated steel boards in order to protect the surface thereof from undesired effects such as deposition of dusts and any scratch, or (ii) as a surface protecting film usable at the time of bake-coating of cars, or dip-soldering of printed-circuit boards. In the present invention, the term “adhesive film” also means an adhesive sheet and an adhesive tape.
BACKGROUND OF THE INVENTION
In recent years, there have been used (1) an adhesive film, which comprises (a) a substrate layer containing a polyolefin resin and (b) an adhesive layer containing a low crystalline or non-crystal polymer such as EVA and low density polyethylene, and (2) an adhesive film, which comprises (a) the same substrate layer as mentioned above and (b) an adhesive layer containing an elastomer such as SIS and SEBS.
However, the above-mentioned adhesive films have problems that (1) stickiness of these adhesive films increases with an elapse of time under a high temperature circumstance, and as a result, it becomes difficult to peel the adhesive film from a surface of an article, or (2) when peeled, the adhesive film leaves an adhesive on a surface of an article.
As an adhesive film free from such an elapsing variation under a high temperature circumstance, JP-A 4-55488 discloses an adhesive film, which comprises (a) a substrate layer containing a thermoplastic resin, and (b) an adhesive layer containing a polyethylene or ethylene/&agr;-olefin copolymer having a density of not higher than 0.92 g/cm
2
and a melt index of from 1 to 20 g/10 min.
Further, JP-A 8-157791 discloses an adhesive film, which comprises (a) an adhesive layer containing an ethylene-&agr;-olefin copolymer having a weight average molecular weight (Mw) of not less than 5×10
4
a ratio (Mw/Mn) between said average molecular weight (Mw) and a number average molecular weight (Mn) of not more than 3, a melting peak temperature and a melting calorie of not lower than 110° C. and not more than 100 j/g according to a DSC analysis, respectively, and (b) a substrate layer containing another polyolefin resin.
However, these adhesive films have problems that (i) their stickiness is extremely low particularly at a low temperature, and (ii) it is difficult to control their stickiness.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an adhesive film, whose stickiness does not vary extremely with an elapse of time even under a low or high temperature circumstance; whose stickiness can be controlled; whose adhesive property, peeling property, re-adhesive property and re-peeling property are satisfactory; which leaves no adhesive on a surface of an article; and which has a superior valance among its flexibility, heat resistance, low temperature resistance and weatherability.
The present inventors have undertaken extensive studies to develop an adhesive film capable of accomplishing the above-mentioned objects. As a result, it has been found that said objects can be accomplished by using an adhesive layer comprising an olefin polymer having specific physical properties, and thereby the present invention has been obtained.
The present invention provides an adhesive film comprising:
(i) a substrate layer, which comprises a thermoplastic resin, and
(ii) an adhesive layer, which comprises an olefin copolymer,
wherein the olefin copolymer comprises polymerization units of at least two olefins selected from the group consisting of ethylene and &agr;-olefins having 3 to 20 carbon atoms, and the olefin copolymer satisfies the requirements:
(a) the olefin copolymer has neither a peak of crystal melting enthalpy of not less than 1 J/g, nor a peak of crystallization enthalpy of not less than 1 J/g in a differential scanning calorimetry according to JIS K 7122, and
(b) a molecular weight distribution of the olefin copolymer, Mw/Mn, is not more than 3.
DETAILED DESCRIPTION OF THE INVENTION
An olefin copolymer used in the present invention means a copolymer comprising polymerization units of at least two olefins selected from the group consisting of ethylene and &agr;-olefins having 3 to 20 carbon atoms. The olefin polymerization unit is hereinafter called like “olefin unit”. The olefin copolymer may contain, if necessary, at least one polymerization unit selected from the group consisting of polyene compound units, cyclic olefin units and vinyl aromatic compound units in addition to the olefin unit.
Examples of the above-mentioned &agr;-olefins having 3 to 20 carbon atoms, polyene compounds, cyclic olefins and vinyl aromatic compounds are as follows.
1. &agr;-Olefin having 3 to 20 Carbon Atoms
As such an &agr;-olefin, linear and branched &agr;-olefins are exemplified. Specific examples of the linear &agr;-olefin are 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-nanodecene and 1-eicocene. Specific examples of the branched &agr;-olefin are 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene and 2,2,4-trimethyl-1-pentene. Of these, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 3-methyl-1-pentene, 3-methyl-1-butene and 4-methyl-1-pentene are preferred.
2. Polyene Compound
As the polyene compound, both a conjugated polyene compound and a non-conjugated polyene compound are preferred. The conjugated polyene compound includes, for example, an aliphatic conjugated polyene compound and an alicyclic conjugated polyene compound. As the aliphatic conjugated polyene compound, a linear aliphatic conjugated polyene compound and a branched aliphatic conjugated polyene compound are exemplified. The aliphatic conjugated polyene compound and the alicyclic conjugated polyene compound may contain a group such as an alkoxy group, an aryl group, an aryloxy group, an aralkyl group and an aralkyloxy group.
Specific examples of the aliphatic conjugated polyene compound are 1,3-butadiene, isoprene, 2-ethyl-1,3-butadiene, 2-propyl-1,3-butadiene, 2-isopropyl-1,3-butadiene, 2-hexyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2,3-diethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 2,3-dichloro-1,3-butadiene, 1-fluoro-1,3-butadiene, 2-chloro-1,3-pentadiene, 2-methyl-1,3-pentadiene, 2-methyl-1,3-hexadiene, 2-methyl-1,3-octadiene, 2-methyl-1,3-decadiene, 2,3-dimethyl-1,3-pentadiene, 2,3-dimethyl-1,3-hexadiene, 2,3-dimethyl-1,3-octadiene and 2,3-dimethyl-1,3-decadiene.
Specific examples of the alicyclic conjugated polyene compound are 2-methyl-1,3-cyclopentadiene, 2-mehtyl-1,3-cyclohexadiene, 2,3-dimethyl-1,3-cyclopentadiene, 2,3-dimethyl-1,3-cyclohexadiene, 2-chloro-1,3-cyclopentadiene and 2-chloro-1,3-cyclohexadiene.
The non-conjugated polyene compound includes, for example, an aliphatic non-conjugated polyene compound, an alicyclic non-conjugated polyene compound and an aromatic non-conjugated polyene compound. As the aliphatic non-conjugated polyene compound, a linear aliphatic non-conjugated polyene compound and a branched aliphatic non-conjugated polyene compound are exemplified. The aliphatic non-conjugated polyene compound, the alicyclic non-conjugated polyene compound and the aromatic non-conjugated polyene compound may contain a group such as an alkoxy group, an aryl group, an aryloxy group, an aralkyl group and an aralkyloxy group.
Specific examples of the aliphatic non-conjugated polyene compound are 1,4-hexadiene, 1,5-hexadiene, 1,6-heptadiene, 1,6-octadiene, 1,7-octadiene, 1,8-nonadiene, 1,9-decadine, 1,13-tetradecadiene, 1,5,9-decatriene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4-ethyl-1,4-hexadiene, 3-methyl-1,5-hexadiene, 3,3-dimethyl-1,4-hexadiene, 3,4-dimethyl-1,5-hexadiene, 5-methyl-1,4-heptadiene, 5-ethyl-1,4-heptadiene, 5-methyl-1,5-heptadiene, 6
Hozumi Hidetake
Ichige Akihiro
Ogawa Atsuko
Sumitomo Chemical Company Ltd.
Tarazano D. Lawrence
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