Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2002-06-06
2004-07-20
Sergent, Rabon (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C264S328100, C264S328600, C528S061000, C528S064000, C528S067000, C528S076000, C528S077000
Reexamination Certificate
active
06765080
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to high performance RIM elastomers, and to a process for the production of these. These elastomers comprise the reaction product of an allophanate-modified diphenylmethane diisocyanate prepolymers having an NCO group content of about 5 to about 30% by weight, with an isocyanate-reactive component comprising a high molecular weight amine-terminated polyether polyol, an aromatic diamine chain extender, and, optionally, a chain extender or crosslinker selected from the group consisting of aliphatic amine-terminated polyether polyols and aliphatic hydroxyl-terminated polyether polyols, optionally in the presence of an internal mold release agent, a surfactant, a filler and/or water.
The production of polyurethane moldings via the reaction injection molding (i.e. RIM) technique is well known and described in, for example, U.S. Pat. No. 4,218,543. The RIM process involves a technique of filling the mold by which highly reactive, liquid starting components are injected into the mold within a very short time by means of a high output, high pressure dosing apparatus after they have been mixed in so-called “positively controlled mixing heads”.
In the production of polyurethane moldings via the RIM process, the reaction mixture generally comprises an A-side based on polyisocyanates and a B-side based on organic compounds containing isocyanate-reactive hydrogen atoms, in addition to suitable chain extenders, catalysts, blowing agents, and other additives. The polyisocyanates which are typically used in a commercial RIM process are the aromatic isocyanates such as, for example, diphenyl methane-4,4′-diisocyanate (i.e.MDI).
U.S. Pat. No. 4,642,320 discloses a process for the preparation of a molded polymer comprising reacting inside a closed mold a reaction mixture comprising (a) an active hydrogen containing material comprising a primary or secondary amine terminated polyether having an average equivalent weight of at least 500 and having at least 25% of active H atoms as amine atoms, (b) at least one chain extender, and (c) a (cyclo)aliphatic polyisocyanate, polyisothiocyanate, or mixture thereof, wherein the NCX index is from about 0.6 to 1.5. All of the examples disclose a system based on a HDI prepolymer with amine terminated polyethers and diethyltoluenediamine at high mold temperatures and long demold times.
U.S. Pat. No. 4,764,543 discloses aliphatic RIM systems that use very fast reacting aliphatic polyamines. This patent is restricted to total polyurea systems based on chain extenders which are cycloaliphatic diamines and polyethers which are amine-terminated polyethers, with an aliphatically bound polyisocyanate.
U.S. Pat. No. 5,260,346 also discloses reaction systems for preparing elastomers via the RIM process. These systems require an allophanate modified polyisocyanate, a hydroxyl group containing polyol, and an aromatic polyamine having at least one of the positions ortho to the amine substituted with a lower alkyl substituent.
U.S. Pat. Nos. 5,502,147 and 5,502,150, which are commonly assigned, describes (cyclo)aliphatic isocyanate based RIM systems. These (cyclo)aliphatic isocyanates have a viscosity of less than 20,000 mPa·s at 25° C., an NCO functionality of 2.3 to 4.0, and are modified by isocyanurate groups, biuret groups, urethane groups, allophanate groups, carbodiimide groups, oxadiazine-trione groups, uretdione groups, and blends thereof, or prepolymers thereof. All of the working examples of these patents are based on hexamethylene diisocyanate which is modified by one of the above groups.
U.S. Pat. No. 4,546,114 discloses high flexural modulus elastomers containing polyurea linkages which are prepared by reaction injection molding, at temperatures of about 90 to about 220° C. (preferably 110 to 190° C.), reaction mixtures comprising an organic polyisocyanate, an organic compound having at least two active hydrogen atoms and a MW of about 1,500 to about 12,000, and an aromatic diamine chain extender wherein at least one of the ortho positions to an amine group is substituted by a lower alkyl group. Suitable polyisocyanates include those aromatic polyisocyanates such as isocyanate-terminated prepolymers of MDI, liquefied MDI, and mixtures thereof. Amine-terminated polyethers having a MW of 1,500 to 12,000 and amine functionalities of 2 to 4 are disclosed, and the diamine chain extenders including DETDA.
RIM molded elastomers made by reacting (a) a di- or polyisocyanate having aromatically bound NCO groups; (b) a polyether having at least 2 NCO-reactive groups and a MW of 1,800 to 12,000 in which at least 50% of the NCO-reactive groups are aromatically bound primary and/or secondary amino groups, and (c) a diamine having a MW of 108 to 400 and containing primary and/or secondary amino groups are also disclosed by U.S. Pat. No. 4,774,264. Allophanate-modified MDI prepolymers are not expressly disclosed as suitable isocyanates.
Polyurethanes formed by a RIM process are disclosed in U.S. Pat. No. 4,631,298. These polyurethanes comprise (a) an organic active hydrogen group containing compound, (b) an organic polyisocyanate, and (c) a chain extender mixture comprising two aromatic diamines having specified gel times. The resultant polyurethanes are described as having a non-brittle, rigid green strength after reaction and a flexural modulus of at least about 50,000 psi at 75° C. Suitable polyisocyanates disclosed therein include allophanate-modified isocyanates and prepolymers thereof. The high molecular weight polyether polyol of the '298 patent is not necessarily an amine-terminated polyether.
U.S. Pat. No. 5,382,646 describes compositions suitable for the preparation of RIM molded polyurethane(urea) parts. These comprise a) an isocyanate component (i.e. a prepolymer), b) a polyether polyol, c) a urethane-promoting catalyst, and d) a hindered diamine chain extender (i.e. DETDA). Isocyanate-terminated prepolymers and some modified isocyanates are disclosed as suitable isocyanate components. Allophanate-modified isocyanates and prepolymers thereof are not expressly disclosed.
Polyurea polymers prepared by reacting a polyisocyanate, a polyepoxide and a polyamine, and heating at a temperature of >150° C. are disclosed by U.S. Pat. No. 5,525,681. Suitable polyamines have a wide range of molecular weights and include, for example, alkylene polyamines, aromatic polyamines (including DETDA), amines derived from polyoxypropylene diols or triols, and mixtures thereof. Suitable polyisocyanates include prepolymers, and allophanate-modified isocyanates, but not allophanate-modified MDI prepolymers.
CA 2,095,677 discloses a process for preparing resilient elastomers containing bonded urethane or urea groups. This process comprises reacting a) a polyisocyanate component, b) a relatively high MW compound containing at least two isocyanate-reactive hydrogen atoms, c) a oxyalkylated polyoxyalkylene polyamine, and d) low MW chain extenders and/or crosslinkers (includes alkyl-substituted aromatic diamines), in the presence or absence of catalysts and additives. These oxyalkylene polyalkylene polyamines N-perethoxylated. Suitable polyisocyanates may contain allophanate groups and/or be a prepolymer.
A process for the production of a RIM molded polyurea elastomer is described in U.S. Pat. No. 5,135,962. Suitable isocyanates include prepolymers, but allophanate-modified isocyanates and prepolymers thereof are not expressly disclosed. The NCO-reactive components consist essentially of (II) a polyether having at least 2 NCO-reactive groups, a MW of 1,800 to 12,000 in which at least 50% of the NCO-reactive groups are primary and/or secondary amino groups, (III) a sterically hindered aromatic diamine chain extender, (IV) a zinc carboxylate containing 10 to 14 carbon atoms per carboxylate group.
U.S. Pat. No. 5,504,179 discloses a RIM process for the manufacture of molded parts. The reaction mixture comprises an isocyanate-terminated prepolymer, an aromatic diamine, an aliphatic reactive component having OH or NH functionality and
Hurley Michael F.
Potts Bruce H.
Slack William E.
Steppan David D.
Super Michael S.
Bayer Corporation
Brown N. Denise
Gil Joseph C.
Sergent Rabon
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