Mixtures leading to hard polyurethane foamed materials

Details Mixtures leading to hard polyurethane foamed materials Mixtures leading to hard polyurethane foamed materials

1996-09-20

1999-02-09

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...

521130, 521131, C08G 1800

Patent

active

058695460

DESCRIPTION:

BRIEF SUMMARY
This application is 35 USC 371 filing of PCT/EP95/01207 filed Mar. 31, 1995, published as WO95/28430 Oct. 26, 1995.
It is known that single-component and two-component polyurethane foamed materials can be produced by reacting mixtures of polyols, foam stabilizers, plasticizers, flame-retardants, accelerators and other process additives, in excess, with di- and/or polyisocyanates in the presence of liquefied foaming gases to form prepolymers containing free isocyanate groups. This reaction is usually conducted in pressure vessels, e.g. in aerosol cans, or (for two-component foamed materials) in unpressurized two-compartment vessels.
When a mixture leading to a single-component foam is discharged, the reaction mass swells due to the volatilization of the foaming agent (frothing). The final foam is obtained by reaction with moisture (e.g. ambient moisture). This can be used in various ways, e.g. for filling and fixing purposes (e.g. for the installation of door frames). When two-component foam systems are used, the mixture is generally cured by reaction with compounds containing at least two active hydrogen atoms as crosslinking agents. Examples of crosslinking agents which are suitable for this purpose include water and/or organic hydroxyl and/or amino compounds.
Surprisingly, it has now been ascertained that by conjointly using special polyisocyanate prepolymers, it is possible firstly to keep the content of monomeric polyisocyanate low (as is also required by legislation), and secondly to obtain hard polyurethane foamed materials having excellent properties for practical application.
The present invention relates to mixtures leading to hard polyurethane foamed materials which mixtures are preferably present in a pressure vessel, and which contain polyisocyanates containing isocyanurate groups and optionally urethane groups with compounds having at least two hydrogen atoms which are reactive to isocyanates and having a molecular weight of 62 to 10,000, wherein the content of monomeric polyisocyanate in the prepolymer is less than 2 weight %,
According to the invention, it is preferred that %, polyisocyanate containing isocyanurate groups and optionally urethane groups, isocyanurate groups and optionally urethane groups, isocyanurate groups and optionally urethane groups, polyisocyanate containing isocyanurate groups and optionally urethane groups, 3 weight %, is used as the polyisocyanate containing isocyanurate groups and optionally urethane groups, dioxide or nitrous oxide, optionally in combination, are used as the foaming agent.
The present invention also relates to hard polyurethane foamed materials obtainable by the curing of the mixtures according to the invention by the action of moisture after their emergence from a pressure vessel ("single-component foamed materials"), or obtainable by the curing of the mixtures by reaction with compounds containing reactive hydrogen atoms and having a molecular weight from 18 to 6000 as crosslinking agents ("two-component foamed materials"). These crosslinking agents are known in the art and may comprise water or organic compounds of ethylene glycol, butanediol or trimethylolpropane, for example.
The starting components for the prepolymers a) to be used according to the invention are: polyisocyanates containing isocyanurate groups and optionally urethane groups. The isocyanate starting materials which are to be modified by isocyanurate groups and optionally by urethane groups are described, for example, by W. Siefken in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, and comprise those of formula preferably 6-10 C atoms, a cycloaliphatic radical containing 4-15 C atoms, preferably 5-10 C atoms, an aromatic hydrocarbon radical containing 6-15 C atoms, preferably 6-13 C atoms, or an araliphatic hydrocarbon radical containing 8-15 C atoms, preferably 8-13 C atoms, e.g. polyisocyanates such as those described in DE-OS 28 32 253, pages 10-11. Aliphatic and/or cycloaliphatic polyisocyanates are particularly preferred, preferably isophorone diisocyanate and hex

REFERENCES:
patent: 4061662 (1977-12-01), Marans et al.
patent: 4645630 (1987-02-01), Rasshofer et al.
patent: 5502147 (1996-03-01), Nodelman et al.
patent: 5502150 (1996-03-01), Steppan et al.

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