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
2000-10-09
2002-12-17
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...
C252S182200, C252S182210, C252S182220, C521S159000, C521S174000, C521S175000, C528S067000, C528S077000, C528S085000, C560S025000, C560S026000, C560S330000, C560S359000
Reexamination Certificate
active
06495652
ABSTRACT:
The present invention relates to novel prepolymers containing isocyanate groups, a process for their preparation by reacting an isocyanate mixture consisting predominantly of diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates with polyols or a mixture of polyols and the use of these prepolymers for producing polyurethanes, in particular polyurethane foams.
The production of polyurethanes, including polyurethane foams, by reacting organic polyisocyanates and/or modified organic polyisocyanates or prepolymers with higher-functionality compounds containing at least two reactive hydrogen atoms, for example polyoxyalkylenepolyamines and/or preferably organic polyhydroxyl compounds, in particular polyetherols having molecular weights of, for example, from 200 to 6000, and, if desired, chain extenders and/or crosslinkers having molecular weights of up to about 400 in the presence of catalysts, blowing agents, auxiliaries and/or additives is known and has been described many times. A summary overview of this is given, for example, in the Kunststoff-Handbuch, Volume VII, “Polyurethane”, 1st Edition 1966, edited by Dr. R. Vieweg and Dr. A. Höchtlen, and 2nd Edition 1983 and 3rd Edition 1993, edited by Dr. G. Oertel (Carl Hanser Verlag, Munich, Vienna).
The chemical structures which are formed from the polyisocyanates and are present here can be polyurethanes, polyureas, polyisocyanurates and also further isocyanate adducts such as allophanates, biurets, carbodiimides and the isocyanate adducts, oxazolidones, polyimides, polyamides, etc. The type of these structures is controlled by means of the compounds which are reacted with the isocyanates, the catalysis and the reaction conditions. These isocyanate adducts are generally summarized under the term polyurethanes since the polyurethanes are the most important and most frequent of the polyisocyanate adducts.
The preparation of NCO prepolymers has also been described in numerous documents, for example in the abovementioned Kunststoff-Handbuch.
For foam production, it is useful if the foam bodies can be quickly removed from the mold immediately after their production. This applies both to removal from a mold in batchwise foam production and to the continuous production of foams, for example using the double conveyor belt method. It is important that the demolding itself takes place without crack formation and/or the foam can, as a result of correspondingly good curing, be subjected as quickly as possible after the synthesis to mechanical treatment, e.g. a sawing step, without crack formation or other destructive occurrences. The foams should have a fine-celled structure. In addition, the flow behavior of the reacting mixture of isocyanate and hydrogen-active materials is of particular importance for foam formation. This flow behavior is, as is known, influenced by the viscosity of the components and thus also of the isocyanate components. A low viscosity of the isocyanate component is necessary for good flow. The required better curing with low crack formation can be achieved in a known manner by, for example, use of a relatively high-viscosity isocyanate having a low proportion of diphenylmethane diisocyanates and a relatively high proportion of polyphenylpolymethylene polyisocyanates. This does not meet the requirement of reducing crack formation at a given constant viscosity of the isocyanate component, i.e. improving the curing immediately after foam formation.
EP-A-0 543 536 describes the production of foams in the presence of a liquid which is largely insoluble in the reaction mixture and is present as an emulsion or microemulsion. This emulsion is said to lead to a more fine-celled structure of the foam. Isocyanate components described for this specific purpose are, apart from customary mixtures of diphenylmethane diisocyanates with polyphenylpolymethylene polyisocyanates, also prepolymers derived from these mixtures and a bifunctional, isocyanate-reactive component in a range from 1 to 150 millimol of urethane/100 g.
WO 93/08224 describes a polyisocyanate composition as a mixture of from 30 to 85% by weight of NCO prepolymer, up to 50% by weight of polyphenylpolymethylene polyisocyanates and up to 40% by weight of diphenylmethane diisocyanates. The advantage indicated is an improved miscibility with rigid foam polyols. For this purpose, considerable parts of the NCO groups are reacted with polyols having a molecular weight from 11,000 g/mol upward, so that NCO contents of the prepolymer far below 30% by weight, in preferred examples from 18.1 to 19.8% by weight, are always obtained. These prepolymers give cells which are still too large in the rigid foam and lead to unsatisfactory curing.
DE-A-4118362 describes the production of pipe insulation via rigid foam having an external compact polyurethane covering layer. Among other things, NCO prepolymers derived from diphenylmethane diisocyanates containing up to 30% by weight of polyphenylpolymethylene polyisocyanates and having an NCO content of the prepolymers of from 5 to 20% by weight are also used.
U.S. Pat. No. 5,164,422 describes the production of polyisocyanurate foams using prepolymers derived from polymeric diphenylmethane diisocyanates and polyester alcohols having a functionality of significantly below 4.
EP-A-0 392 788 discloses a prepolymer derived from diphenylmethane diisocyanates for the production of purely water-blown foams; this prepolymer has an NCO content of from 2 to 12% by weight of NCO. The viscosity is too high for normal foam processing, namely 38,000 mPas in a preferred example.
EP-A-0 320 134 describes prepolymers derived from diphenylmethane diisocyanates and polyols having a functionality of significantly below 4 as constituents of a mixture with diphenylmethane diisocyanates and polyphenylpolymethylene polyisocyanates for producing rigid foam.
AU 8767-425 describes the use of prepolymers derived from a mixture of from 45 to 95% by weight of diphenylmethane diisocyanates and from 5 to 55% by weight of polyphenylpolymethylene polyisocyanates and polyester polyols having a mean functionality of significantly less than 4, the prepolymers having an NCO content of significantly less than 30% by weight for producing flexible foam having excellent adhesion to PVC.
SU 876 657 describes the use of a prepolymer derived from a mixture of from 75 to 65 parts of diphenylmethane diisocyanates with from 25 to 35 parts of polyphenylpolymethylene polyisocyanates and triols for integral rigid foam.
NL 7605 286 describes the use of a prepolymer derived from diphenylmethane diisocyanates in admixture with their uretoneimines and diols.
DT 2513 793 and DT 2513 796 describe the use of a prepolymer derived from a mixture of from 55 to 85 parts of diphenylmethane diisocyanates with polyphenylpolymethylene polyisocyanates and diols.
In EP-A-0 550 901, isocyanates of the diphenylmethane series having a proportion of from 75 to 95% by weight of two-ring isomers with a proportion of 2,4′-isomers of from 15 to 40% by weight and of 2,2′-isomers of from 2 to 10% by weight and also a proportion of from 5 to 25% by weight of polymeric isocyanates of the diphenylmethane series are reacted with polyether polyols having a functionality of from 3 to 8, and an OH number of from 350 to 1000 mg KOH/g and a molecular weight of from 150 to 1000 g/mol. The main object of this invention is the preparation of light-colored isocyanate components from which particularly light-colored rigid polyurethane foams can then be produced.
In WO 94/29361 prepolymers having NCO contents of from 5 to 10% by weight are produced by reacting isocyanates with polyols at from 40 to 80° C., with the reaction being carried out conventionally, i.e. in a reaction vessel suitable for this purpose.
U.S. Pat. No. 5,114,989 discloses, for example, MDI prepolymers which are reacted with polyols rich in ethylene oxide. It is stated here that the metered addition of polyol to the initial charge of isocyanate in the reactor has to be carried out so that a temperature in the range from 45 to 90
Falke Peter
Hempel Renate
Reichelt Michael
Rotermund Udo
Seifert Holger
BASF - Aktiengesellschaft
Borrego Fernando A.
Sergent Rabon
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