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
1999-06-14
2001-12-18
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...
C525S210000, C525S211000, C525S240000
Reexamination Certificate
active
06331593
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a resin composition pellet, a method for producing a resin composition pellet, a modifier for a polyolefin-based resin and a method for producing a polyolefin-based resin composition. More particularly, the present invention relates to a technology which can be used to provide a polyolefin based resin composition that has excellent flexibility and transparency characteristics, exhibits a suppressed (reduced) tendency for pellets to agglomerate (adhere to one another), and thus has excellent handling properties and excellent workability. The present invention relates to a resin composition pellet having the above-described features, a method for producing the resin composition pellet, a modifier for a polyolefin-based resin and a method for producing a polyolefin-based resin composition. When resin composition pellets show a high tendency to adhere to one another, the adhered pellets form lumps during storage. Lump formation is extremely disadvantageous in the subsequent measurement, input operation into a kneader, and the like.
2. Description of the Related Art
Polyolefin-based resins, typically including polypropylene, suffer from defects such as poor flexibility and transparency while having excellent strength and heat resistance. There is known a technology using a flexibility imparting agent for giving flexibility and transparency to polyolefin-based resins. However, according to conventional technologies, a flexibility imparting agent presents significant adhesion problems. It tends to adhere under slight loads and consequently can not in the form of a small shape such as a pellet and the like for a long period of time. Therefore, flexibility imparting agents have problems of extremely poor handling and workability such as in transportation, measurement and the like in compounding into polyolefin-based resins.
SUMMARY OF THE INVENTION
An object of the present invention is to overcome the above-described problems with a production technology so that a polyolefin-based resin composition can be effectively obtained which exhibits excellent flexibility and transparency. More particularly, the present invention provides a resin composition pellet that has excellent non-mutual adhesion (non-agglomerating characters), storability and handling, a method for producing such a resin composition pellet, a modifier for a polyolefin-based resin in the form of a pellet composed of the composition and a method for producing a polyolefin-based resin composition.
The present invention relates to a resin composition pellet comprising:
(i) 15 to 65% by weight of a polyolefin-based resin, and
(ii) 85 to 35% by weight of an olefin-based copolymer obtained by copolymerizing two or more olefins selected from ethylene, propylene and &agr;-olefins having 4 to 20 carbon atoms in the presence of a catalyst for olefin polymerization, the total number of carbon atoms in the selected olefins being 7 or more.
The present invention also relates a method for producing a resin composition pellet, wherein the above-described resin (i) and copolymer (ii) are kneaded at a temperature, which is not less than the maximum peak temperature (Tm), as measured by differential scanning calorimetry (DSC)and not higher than 280° C.
The present invention also relates a polyolefin-based resin modifier comprising the above-described polyolefin-based resin composition pellet.
The present invention also relates to a method for producing a polyolefin-based resin composition comprising compounding the above-described polyolefin-based resin modifier into a polyolefin-based resin.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The component (i) in the present invention is a polyolefin-based resin. Examples thereof include high density polyethylene, medium density polyethylene, low density polyethylene, LLDPE (linear low density polyethylene), polypropylene-based resins, poly-4-methylpentene-1 and the like. Polypropylene-based resins are preferred.
A polypropylene-based resin that can be used in the composition of the present invention is a crystalline polypropylene-based resin, and is a homopolymer of propylene, or a random or block copolymer of propylene with a small amount of &agr;-olefin and/or ethylene. If the above-described polypropylene-based resin is a random copolymer, the copolymerization proportion of other &agr;-olefin and/or ethylene in the copolymer is generally 10% by weight or less, preferably from 0.5 to 7% by weight in total. If it is a block copolymer, the copolymerization proportion of other &agr;-olefin and/or ethylene in the copolymer is generally from 1 to 40% by weight, preferably from 1 to 25% by weight, further from 2 to 20% by weight, and particularly preferably from 3 to 15% by weight. These polypropylene-based polymers may be composed of two or more polymers together. As indices of the crystalline property of the polypropylene, melting point, crystal melting calorie and the like are used. For example, it is preferred that the melting point be in the range from 120° C. to 176° C. and the crystal melting calorie be in the range from 60 J/g to 120 J/g. When the melting point of a crystal is too low or the melting calorie thereof is too low, heat resistance of the raw material may consequently decrease.
There are methods that may, in general, be identified for the production of a polyolefin-based resin. There may be generally listed methods in which a propylene homopolymer is obtained by homopolymerizing propylene in a one-step or multi-step process according to slurry polymerization, gas-phase polymerization, bulk polymerization, solution polymerization or a combination thereof There may also be listed methods in which a propylene &agr;-olefin copolymer is obtained by copolymerizing propylene with an &agr;-olefin having 2 or 4 to 12 carbon atoms, preferably ethylene, in a one-step or multi-step process. A polymerization can be catzed using a Ziegler Natta type catalyst, which comprises a titanium-containing solid state transition metal component and an organometallic component, or catalyzed using a metallocene catalyst, which comprises a transition metal compound of from Groups 4A to 6A in the periodic table, which compound has at least one cyclopentadienyl skeleton, in combination with an auxiliary catalyst component. Further, corresponding commercially available products can be used as the component (i).
The component (ii) in the present invention is an olefin-based copolymer obtained by copolymerizing two or more olefins selected from ethylene, propylene and &agr;-olefins having 4 to 20 carbon atoms in the presence of a catalyst for olefin polymerization, wherein the total number of carbon atoms in the selected olefins is at least 7. It is necessary that the total number of carbon atoms in the selected olefins is 7 or more. If the total number of carbon atoms in the selected olefins is less than 7, a molded article obtained by using the resulting polyolefin-based resin composition exhibits poor flexibility and transparency.
The &agr;-olefins having 4 to 20 carbon atoms include linear and branched &agr;-olefins. Specific examples of linear &agr;-olefins include 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, 1-eicosene and the like. Specific examples of branched &agr;-olefins include 3-methyl-1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, 2-ethyl-1-hexene, 2,2,4-trimethyl-1-pentene and the like.
Specific examples of combinations of two or more selected olefins include ethylene/1-pentene, ethylene/1-hexene, ethylene/1-octene, ethylene/1-decene, ethylene/1-octadecene, ethylene/4-methyl/1-pentene, propylene/1-butene, propylene/1-pentene, propylene/1-hexene, propylene/i-octene, propylene/1-decene, propylene/i-octadecene, propylene/4-methyl-1-pentene, 1-butene/1-pentene, 1-butene/1-hexene, 1-butene/1-octene, 1-butene/1-decene, 1-butene/1-octadecene, 1-butene/4-methyl-1
Johoji Hirofumi
Kuwabara Toshiyuki
Fitch Even Tabin & Flannery
Nutter Nathan M.
Sumitomo Chemical Limited., Co.
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