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
2000-11-13
2002-07-30
Mullis, Jeffrey (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...
C525S322000, C525S324000
Reexamination Certificate
active
06426388
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a novel chlorine-free modified polyolefin composition with excellent adherence to nonpolar sheets, films and moldings of polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, etc., with excellent solvent resistance, oil resistance and weather resistance, with no tack, and also with excellent cohesion.
Because of low price, and many excellent properties such as moldability, chemical resistance, water resistance and electrical characteristics, polyolefins such as polypropylene and polyethylene are used widely in recent years as sheets, films, moldings, etc. Different from polar substrates such as polyurethane resin, polyamide resin, acrylic resin and polyester resin, however, polyolefin substrates are nonpolar and crystalline, leading to drawbacks of difficult paintability and adhesion.
So far, modified polyolefins obtainable by modifying polyolefins with unsaturated carboxylic acid and/or acid anhydride, and further acid-modified chlorinated polyolefins obtainable by chlorinating them have been used as paint additives, primers and adhesives, because of excellent adherence to said nonpolar substrates.
However, conventional acid-modified polyolefins represented by maleic anhydride-modified polyolefins have drawbacks of poorer adherence to non-polar substrates, more liability to cause cohesive failure, stronger tackiness, etc. compared with chlorination type modified polyolefins. Moreover, even chlorinated polyolefins with excellent adherence also have drawbacks of poor weather resistance etc. and, in addition, from recent upsurge of environmental problems, their uses have also become to be restricted. Based on such background, the development of novel chlorine-free resin with adherence to nonpolar substrates equal to or more than that of chlorinated polyolefin, and also with excellent physical properties such as tackiness and cohesion has been expected.
As one of the reasons why maleic anhydride-modified polyolefin is in short of physical properties, low activity of maleic anhydride on radical polymerization can be mentioned. In order to use maleic anhydride-modified polyolefin for the uses of adhesives, primers, paint additives, etc. for nonpolar substrates, at which the invention aims, it is required to graft a considerable quantity of maleic anhydrides onto polyolefin. However, because of low grafting rate by usual modification method, necessary physical properties cannot be obtained. If employing severe conditions in attempt to raise the grafting rate, then remarkable decrease in molecular weight results, leading to decreased physical properties. In the uses of compatibilizers, moldings, adhesives, etc., such techniques for obtaining modified polyolefin with high molecular weight and high grafting rate that use of maleic anhydride and styrenic monomer in combination are known, and, for example, U.S. Pat. No. 3,708,555, Japanese Unexamined Patent Publication Nos. Hei 1-221475, Hei 8-3415, 48873, 208907, Hei 10-36456, 306269, etc. are exemplified, including the literatures described in G. Moad: Prog. Polym. Sci., 24, 81 (1999). With these techniques, styrenic monomer equal to or more quantity than maleic anhydride is used. Moreover, in U.S. Pat. No. 5,021,510, Japanese Unexamined Patent Publication Nos. Hei 3-227341, Hei 4-46946, Hei 6-122738, Hei 9-40724, etc., the ratio of maleic anhydride to styrenic monomer is not particularly described, or the techniques cover very broad range.
However, in the uses, at which the invention aims, these conventional techniques could not be utilized from the facts that the solvent resistance, oil resistance and weather resistance decreased remarkably because of a large quantity of styrenic components contained. Moreover, in the case of low content of propylene in raw material polyolefin or in the case of high content of styrenic component in modified polyolefin, the adherence to nonpolar substrates decreased, which made it impossible similarly to utilize for those uses.
The purpose of the invention lies in providing a novel chlorine-free modified polyolefin with excellent adherence to polyolefinic resin moldings, with excellent solvent resistance, oil resistance and weather resistance, with no tack, and also with excellent cohesion.
As a result of diligent investigations for solving this subject, the inventors have found that, by using particular polyolefin for raw material and further using particular quantities of maleic anhydride and styrenic monomer for graft polymerization, thus by controlling the structure and molecular weight of modified product, the adherence to nonpolar substrates, solvent resistance, oil resistance, weather resistance, elimination of tack and enhancement of cohesion, etc. can be achieved at the same time, leading to the invention based on this knowledge.
SUMMARY OF THE INVENTION
As described, according to the invention, following (1) through (9) are provided.
(1) A modified polyolefin composition having the weight average molecular weight of not less than 30,000 to not more than 150,000, obtainable by graft polymerizing 0.5 to 15.0% (by weight) of (B) maleic anhydride and 0.1 to 7.5% (by weight)of (C) styrenic monomer to (A) polypropylene, ethylene-propylene copolymer or ethylene-propylene-butene copolymer, so as the grafting weight ratio (B/C) of (B) to (C) to become not less than 2 to not more than 5.
(2) The modified polyolefin composition described in (1), wherein the composition ratio of propylene in (A) polypropylene, ethylenepropylene copolymer or ethylene-propylene-butenecopolymer described is not less than 50%.
(3) A modified polyolefin composition obtainable by graft polymerizing (B) maleic anhydride and (C) styrenic monomer onto polyolefin, characterized by said polyolefin being (A) polypropylene, ethylene-propylene copolymer or ethylene-propylene-butene copolymer, the grafting rates of (B) to (A) being 0.5 to 15.0% (by weight) and of (C) to (A) being 0.1 to 7.5% (by weight), the weight ratio (B/C) of grafting rate of (B) to the grafting rate of (C) being not less than 2 to not more than 5, and the weight average molecular weight of the graft polymer grafted (B) and (C) onto (A) being not less than 30,000 to not more than 150,000.
(4) The modified polyolefin composition described in (3), wherein the composition ratio of propylene (by weight) in (A) polypropylene, ethylene-propylene copolymer or ethylene-propylene-butene copolymer is not less than 50%.
(5) The modified polyolefin composition described in (3) or (4), wherein it is a chlorine-free modified polyolefin composition.
(6) An adhesive using the modified polyolefin composition of (1) through (5).
(7) A primer using the modified polyolefin composition of (1) through (5).
(8) A paint binder using the modified polyolefin composition of (1) through (5).
(9) An ink binder using the modified polyolefin composition of (1) through (5).
DETAILED DESCRIPTION OF THE INVENTION
The nonpolar substrates referred to so in the invention point to nonpolar sheets, films or moldings of polypropylene, polyethylene, ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, etc. Also, they include surface-treated ones of these substrates with plasma, corona or the like.
The polyolefins that become the raw material of modified polyolefin to be used in the invention are polypropylene, ethylene-propylene copolymer and ethylene-propylene-butene copolymer.
The composition ratio of propylene in the polyolefins that become the raw material of modified polyolefin is preferable to be not less than 50%, more preferably not less than 60% to not more than 98%. If under 50%, then the adherence to propylene and polyolefin substrates is poor.
The usable molecular weight of polyolefin can be selected freely so as the weight average molecular weight of modified polyolefin to become 30,000 to 150,000, but, even a polyolefin with weight average molecular weight of over 150,000 becomes usable by the publicly known m
Fujino Ken-ichi
Fujitaka Terumasa
Masumoto Kouji
Usui Kazuhiro
Yoshioka Hidetoshi
Mullis Jeffrey
Nippon Paper Industries Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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