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
1997-02-18
2002-04-02
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C525S131000, C528S028000, C528S044000, C528S076000, C528S084000, C528S085000
Reexamination Certificate
active
06365674
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to polyurethanes and more particularly to a thermoplastic molding composition containing a resinous blend of polyurethane and a polyolefin.
SUMMARY OF THE INVENTION
A thermoplastic polyurethane resin which is prepared by reacting an isocyanate, a polyol and a reactive polyolefin, and a chain extender, is disclosed. It was surprisingly and unexpectedly found that the inventive resin forms compatible blends with polyolefins.
BACKGROUND OF THE INVENTION
Conventional thermoplastic polyurethane resins are the reaction product of a diisocyanate, a chain extender (a short chain diol) and a polyol. It has long been recognized that such polyurethane resins are incompatible with, and hence not easily blended with, polyolefins such as polyethylene and polypropylene. This incompatibility results in inhomo-geneous blends which tend to delaminate and often feature poor mechanical properties.
U.S. Pat. No. 4,883,837 and the document mentioned there as prior art reflect the many attempts to make compatible blends of polyolefins with thermoplastic polyurethane. Note may also be made of U.S. Pat. No. 4,752,626 which disclosed a polyisocyanate prepared from a polyol blend containing polyolefinic polyol. A polyolefin diol was referred to in U.S. Pat. No. 5,332,786 as a reactant with diisocyanate in the preparation of an adhesive.
DETAILED DESCRIPTION OF THE INVENTION
The reactants necessary in the preparation of the thermoplastic polyurethane resin of the present invention comprise
(i) at least one member selected from among aliphatic and aromatic isocyanates, and
(ii) at least one polymeric polyol, most preferably a member selected from between polyester polyol and polyether polyol, and
(iii) a reactive polyolefin which contains at least one member selected from hydroxyl, amine and carboxylic acid functional groups, and
(iv) a chain extender.
Importantly, the amount of said (iii) is at least 1.0 equivalent %, preferably at least 8 equivalent %, relative to the amount of said (ii) and the ratio of said isocyanate equivalents to equivalents of active hydrogen-containing materials is within the range of 0.90:1 to 1.10:1, and preferably, 0.95:1 to 1.05:1.
The chain extender suitable in the present context is a C
2-10
hydrocarbon compound having an isocyanate-reactive chain termination. In a preferred embodiment of the invention, the chain extender is hydroxy and/or an amine terminated. In a further embodiment of the invention, additional polyols may be included as reactants.
An additional embodiment of the invention relates to a thermo-plastic composition containing a blend of the polyurethane of the invention and polyolefin resin. The polyurethane of the invention was found to be more compatible with polyolefin than other prior art polyurethanes.
The isocyanate suitable in the present invention is any of the organic isocyanates previously disclosed as suitable in the preparation of TPU resins, preferably diisocyanates, and include aliphatic, aromatic and cycloaliphatic diisocyanates, and mixtures thereof.
Illustrative isocyanates but non-limiting thereof are methylenebis(phenyl isocyanate) including the 4,4′-isomer, the 2,4′-isomer and mixtures thereof, m- and p-phenylene diisocyanates, chlorophenylene diisocyanates, a,a′-xylylene diisocyanate, 2,4- and 2,6-toluene diisocyanate and the mixtures of these latter two isomers which are available commercially, tolidine diisocyanate, hexamethylene diisocyanate, 1,5-naphthalene diisocyanate, isophorone diisocyanate and the like; cycloaliphatic diisocyanates such as methylenebis(cyclohexyl isocyanate) including the 4,4′-isomer, the 2,4′-isomer and mixtures thereof, and all the geometric isomers thereof including trans/trans, cis/trans, cis/cis and mixtures thereof, cyclohexylene diisocyanates (1,2-; 1,3-; or 1,4-, 1-methyl-2,5-cyclohexylene diisocyanate, 1-methyl-2,4-cyclohexylene diisocyanate, 1-methyl-2,6-cyclohexylene diisocyanate, 4,4′-isopropylidenebis(cyclohexyl isocyanate), 4,4′-diisocyanatodicyclohexyl, and all geometric isomers and mixtures thereof and the like. Also included are the modified forms of methylenebis(phenyl isocyanate). By the latter are meant those forms of methylenebis(phenyl isocyanate) which have been treated to render them stable liquids at ambient temperature (circa 20° C.). Such products include those which have been reacted with a minor amount (up to about 0.2 equivalents per equivalent of polyisocyanate) of an aliphatic glycol or a mixture of aliphatic glycols such as the modified methylenebis(phenyl isocyanates) described in U.S. Pat. Nos. 3,394,164; 3,644,457; 3,883,571; 4,031,026; 4,118,411; and 4,299,347. The modified methylenebis(phenyl isocyanates) also include those which have been treated so as to convert a minor proportion of the diisocyanate to the corresponding carbodiimide which then interacts with further diisocyanate to form uretone-imine groups, the resulting product being a stable liquid at ambient temperatures as described, for example, in U.S. Pat. No. 3,384,653. Mixtures of any of the above-named isocyanates can be employed if desired.
Preferred classes of organic diisocyanates include the aromatic and cycloaliphatic diisocyanates. Preferred species within these classes are methylenebis(phenyl isocyanate) including the 4,4′-isomer, the 2,4′-isomer, and mixtures thereof, and methylenebis(cyclohexyl isocyanate) inclusive of the isomers described above.
The preferred isocyanates are methylene bis(phenyl isocyanate) and methylene bis(cyclohexyl isocyanate).
The polymeric diols suitable in the context of the invention are those conventionally employed in the art for the preparation of TPU resins. The formation of soft segments in the resulting polymer is attributed to the polymeric diols. Preferably, the polymeric diols have molecular weights (number average) within the range of 500 to 10,000, preferably 1000 to 4,000. Naturally, and often times advantageously, mixtures of such diols are also possible. Examples of the suitable diols include polyether diols, polyester diols, hydroxy-terminated polycarbonates, hydroxy-terminated copolymers of dialkyl siloxane and alkylene oxides such as ethylene oxide, propylene oxide and the like, and mixtures thereof.
Examples of suitable polyether polyols include polyoxyethylene glycols, polyoxypropylene glycols which, optionally, have been capped with ethylene oxide residues, random and block copolymers of ethylene oxide and propylene oxide; polytetramethylene glycol, random and block copolymers of tetrahydrofuran and ethylene oxide and/or propylene oxide. The preferred polyether polyols are random and block copolymers of ethylene and propylene oxide of functionality approximately 2.0 and polytetramethylene glycol polymers of functionality about 2.0.
The suitable polyester polyols include the ones which are prepared by polymerizing &egr;-caprolactone using an initiator such as ethylene glycol, ethanolamine and the like, and those prepared by esterification of polycarboxylic acids such as phthalic, terephthalic, succinic, glutaric, adipic, azelaic and the like acids with polyhydric alcohols such as ethylene glycol, butanediol, cyclohexane-dimethanol and the like. An example of a suitable polyester polyol is butanediol adipate.
Among the suitable amine-terminated polyethers, mention may be made of the aliphatic primary diamines structurally derived from polyoxypropylene glycols. Polyether diamines of this type are available under the trademark JEFFAMINE from Jefferson Chemical Company.
Examples of polycarbonates containing hydroxyl groups include those prepared by reaction of diols such as propane-1,3-diol, butane-1,4-diol, hexane-1,6-diol, 1,9-nonanediol, 2-methyloctane-1,8-diol, diethylene glycol, triethylene glycol, dipropylene glycol and the like with diaryl-carbonates such as diphenylcarbonate or with phosgene.
Examples of suitable silicon-containing polyethers include copolymers of alkylene oxides with dialkylsiloxanes such as dimethyl-siloxane and the like; other suitable
Kaufhold Wolfgang
Rosthauser James W.
Wiggins Jeffrey S.
Bayer Corporation
Niland Patrick D.
Preis Aron
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