Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Reexamination Certificate
1999-12-03
2002-03-12
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S198000, C524S199000, C524S589000, C528S044000, C528S069000
Reexamination Certificate
active
06355721
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to high molecular weight liquid, non-functional polyether polyurethane plasticizers. It is also directed to a process for the production of these plasticizers, a process for the production of a polyurethane comprising the reaction between an isocyanate component and an isocyanate-reactive component in the presence of these plasticizers, and to the polyurethanes produced by that process.
Plasticizers are generally used in plastics (i.e., PVC) to adjust hardness, flexibility and processing characteristics. Plasticizers are also used in commercial polyurethane elastomer formulations to provide products exhibiting higher flexibility, lower hardness, and lower rebound resulting in increased energy absorption. However, these products can potentially embrittle over time due to migration of the plasticizer. Plasticizers that have a minimal effect on hardness and physical properties, and which are non-migrating are desirable for polyurethane elastomers prepared by a one-shot cast elastomer process.
Diurethanes are known and described as suitable stabilizing additives for sealing compounds in, for example, U.S. Pat. No. 4,824,888 and as plasticizers for polyurethane based sealing and adhesive compositions in U.S. Pat. No. 5,525,654.
U.S. Pat. No. 4,824,888 discloses diurethanes which correspond to one of two general formulas, which are useful as stabilizing additives in sealing compounds based on isocyanate-terminated prepolymers of difunctional and trifunctional polyether or polyester polyols and/or polyvinylchloride swellable copolymers of vinyl chloride with monomers from the group vinyl acetate, vinyl propionate, alkyl acrylates. These diurethanes are reaction products of monofunctional alcohols and diisocyanates. In particular, the monoalcohols are monofunctional polypropylene glycol monoalkyl ethers having a molecular weight of about 500 to 2000. These diurethanes are also suitable stabilizing agents for isocyanate-terminated polyurethane prepolymers, and for polyvinyl chloride homopolymer or copolymer plastisols.
Moisture curing sealing and/or adhesive compositions based on alkoxysilane-terminated polyurethanes which contain diurethanes as plasticizers are described by U.S. Pat. No. 5,525,654. These diurethanes are prepared from either diol mixtures and monofunctional isocyanates wherein substantially all the free hydroxyl groups are reacted, or from diisocyanates and monofunctional alcohols wherein substantially all the free isocyanate groups are reacted.
Other urethane plasticizers are disclosed in, for example, U.S. Pat. Nos. 4,123,413 and 4,482,408. The urethane plasticizers of U.S. Pat. No. 4,123,413 correspond to one of three general formulas, and are prepared by reaction of an alcohol or a phenol with an isocyanate, from amines and chloroformates, or from chloroformamides and alcohols or phenols in the presence of acid binding agents.
The urethane plasticizer of U.S. Pat. No. 4,482,408 is octyldecyl-butyl urethane and is prepared by reacting an equimolar mixture of octyldecyl isocyanate and n-butyl alcohol. This urethane plasticizer is a mono-urethane described as a straight-chain, saturated, carbamic acid ester and is suitable as a plasticizer for propellant compositions with problems of plasticizer migration which typically occur during propellant storage.
Useful polyurethane plasticizers according to the present invention are based on high molecular weight polyether diisocyanate prepolymers reacted with monoalcohols or mixtures of monoalcohols. They are prepared by either adding the alcohols to the prepolymer or by addition of the prepolymer to the monofunctional alcohol(s). The polyurethane plasticizers are liquid at 25° C. and usually exhibit low viscosity. The resulting polyurethanes do not contain any free hydroxyl- or isocyanate-groups, and thus they are non-reactive and can be added to either isocyanates or polyols to form stable mixtures.
The use of these polyurethane plasticizers in one-shot polyurethane elastomers has several important benefits:
1) Addition to either the polyol or the isocyanate composition allows one to adjust the mix ratio very favorably, i.e., to adjust a 1:1.5 ratio to an easier to process ratio of 1:1.
2) Addition to either the polyol or the isocyanate compositions allows one to adjust the viscosities of the two components very favorably, i.e., to obtain viscosities which are similar which facilitates the mixing process.
3) Unmodified polyisocyanates that contain no urethane, allophanate, urea, or biuret groups are usually very incompatible with polyol compositions due to major differences in surface energy (i.e., polarity). Addition of the diurethane containing plasticizers according to the invention to either the polyisocyanate or both the polyisocyanate and polyol side of one-shot elastomer formulations helps to overcome these incompatibility problems and thus facilitates mixing.
Although it is possible in one-shot elastomer formulations to meter the single components separately and mix them, i.e., in a reactor or mixhead, it is preferred to combine the polyurethane containing plasticizer with the polyisocyanate and/or the polyol/chain extender blend prior to mixing the isocyanate containing the isocyanate reactive polyol components.
Besides the processing advantages polyurethane plasticizers provided in one-shot polyurethane elastomer formulations, they do not show any substantial migration or lower the physical properties of the final polyurethane elastomer upon aging to the extent observed in state of the art non-urethane group containing plasticizers. As a result, the high performance properties of one-shot polyurethane elastomers upon aging are effected minorly when polyurethane containing plasticizers are used in the formulation.
SUMMARY OF THE INVENTION
This invention relates to high molecular weight liquid, non-migrating, non-functional, polyurethane plasticizers having a viscosity of less than about 50,000 mPa·s at 25° C. These plasticizers comprise the reaction product of (1) an isocyanate-terminated polyether prepolymer having an NCO group content of less than 13%, and (2) a monofunctional alcohol having a molecular weight of about 32 to about 1,000, preferably of about 128 to about 720, and an OH number of about 56 to about 1750, preferably of about 78 to about 438.
As used herein, the phrase high molecular weight liquid, non-migrating, non-functional polyether polyurethane plasticizers having a viscosity of less than about 50,000 mPa·s at 25° C. refers to adducts having molecular weights in the range of from about 3,000 to about 6,500. It is preferred that these plasticizers have a ratio of carbon atoms to oxygen atoms of less than 5:1.
Suitable (1) isocyanate-terminated polyether prepolymers comprise the reaction product of (a) a diisocyanate component having an NCO group content of about 32.0 to about 60.0%, preferably of about 33.6%, and a functionality of about 2.0; with (b) at least one polyether polyol having a molecular weight of about 1,000 to less than about 5,000, preferably of about 2,000 to about 4,000, an OH number of about 23 to about 168 and a functionality of from about 2 to about 3. The amounts of (1)(a) diisocyanate and (1)(b) polyether polyol are such that the NCO:OH equivalent ratio in the prepolymer is from about 2:1 to about 7:1, and preferably from about 3:1 to about 5:1.
This invention also relates to a process for the production of these high molecular weight liquid, non-migrating, non-functional polyether polyurethane plasticizers that are characterized by a viscosity of less than about 50,000 mPa·s at 25° C., and preferably a carbon to oxygen ratio of less than 5:1. This process comprises:
(1) reacting
(a) a diisocyanate component having an NCO group content of about 32.0 to about 60.0%, and a functionality of about 2.0, with
(b) at least one polyether polyol having a molecular weight of about 1,000 to less than about 5,000, an OH number of about 23 to about 168, and a functionality of from about 2 to about 3,
at an NCO:OH equivalent ratio of fro
Markusch Peter H.
Pantone Richard S.
Bayer Coporation
Brown N. Denise
Gil Joseph C.
Niland Patrick D.
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