Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1998-12-17
2000-01-11
Cooney, Jr., John M.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
521159, 521163, 521170, C08G 1804
Patent
active
060136928
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to cellular polyurethane elastomers, in particular those which can be subjected to high dynamic stresses.
2. Background Art
High requirements are placed upon the materials of cellular polyurethane elastomers applied, for example, in passenger or freight vehicle springing systems or in buffer and bumper systems subject to high dynamic stresses. Cellular polyurethane elastomers based on methylenebis-(phenyl isocyanate) (MDI) or tolylene diisocyanate (TDI) have hitherto not been able to fulfil these high requirements and have therefore so far been used for applications subject to lower dynamic stresses. The chain extending agents used in these systems are usually glycols, in particular butanediols. The resultant hard polyurethane segments have a melting range from about 180.degree. to 200.degree. C., and for cases of high dynamic or thermal stress this markedly impairs the mechanical properties of the products produced therefrom. The standard for applications involving high dynamic stresses has hitherto been cellular polyurethane elastomers based on naphthylene diisocyanate (NDI) and known as "Vulkollan". These cellular polyurethane elastomers show good behavior under dynamic stress, but they have the disadvantage that the prepolymers are not stable when stored (cf. Kunststoff Taschenbuch [Plastics Handbook], 24th edition, Carl Hanser Verlag, Munich, 1989, pp. 436ff.). The consequence for the final producer is therefore that only in-line production is possible, the prepolymer being converted immediately into the finished part. NDI-containing products also differ from industrially produced MDI products in having a significantly higher price level.
BROAD DESCRIPTION OF THE INVENTION
It was therefore the object of the invention to develop cellular polyurethane elastomers which utilize the advantageous properties of methylenebis(phenyl isocyanate) (MDI) and tolylene diisocyanate (TDI) with respect to storage capability of the prepolymers and to availability and advantageous price, and which in their material properties achieve the requirements for applications involving high dynamic stresses.
The object was achieved with cellular polyurethane elastomers according to of the invention.
According to the invention, the cellular polyurethane elastomer may be produced by reacting (MDI) and/or tolylene diisocyanate (TDI), in monomeric form or as liquefied prepolymer with 4,4'-methylenebis(3-chloro-2,6-dialkylaniline) with one or more aromatic, aliphatic or cycloaliphatic diamines as chain extending agent, if desired with further polyol, and and other additives.
The isocyanate component MDI is generally monomeric 4,4'-methylenebis(phenyl isocyanate) or pre-polymers thereof liquefied with small proportions of polyol. However, this term also includes an MDI which expediently contains proportions of up to 30% by weight of the isomeric 2,4'-methylenebis(phenyl isocyanate). Mixtures of MDI with other polyisocyanates, for example with tolylene diisocyanate (TDI) or with other industrially obtainable diisocyanates, for example hexamethylene diisocyanate or isophorone diisocyanate, are likewise included in this term. It is, however, also possible to obtain commercially, and use, the MDI in the form of a prepolymer with a particular NCO content, for example under the name Vibrathane.RTM..
The tolylene diisocyanate is generally either the isomerically pure 2,4- or 2,6-isomer or any desired mixture of these isomers with one another. An isomer mixture of the 2,4- and 2,6-isomers in a ratio of 80:20 or 65:35 is, for example, known and obtainable in industrial quantities. It is, however, also possible to obtain commercially, and use, the TDI in the form of a prepolymer with a particular NCO content, for example under the name Vibrathane.RTM..
Examples of suitable compounds with at least two polyisocyanate-reactive hydrogen atoms are in particular polyols, for example polyether polyols, polyester polyols or other polyols (e.g. polycaprolactones) with a mole
REFERENCES:
patent: 3523918 (1970-08-01), Gonzalez
patent: 3752790 (1973-08-01), McShane, Jr. et al.
patent: 4950792 (1990-08-01), Althaus et al.
patent: 5026815 (1991-06-01), Volker et al.
PCT Request in PCT/EP96/05542 (1996).
Notice Informing The Applicant Of Communication Of The International Application To The Designated Offices (1996).
Daum Ulrich
Feeken Arno
Jarre Wolfgang
Schmidt Andreas
Sklenarz Reinhard
Cooney Jr. John M.
Lonza AG
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