Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2002-01-15
2003-06-24
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S159000, C521S170000, C521S174000
Reexamination Certificate
active
06583192
ABSTRACT:
The preparation of polyurethane foams by reacting organic and/or modified organic polyisocyanates and prepolymers with compounds which have a higher functionality and at least two reactive hydrogen atoms, for example polyoxyalkylenepolyamines and/or preferably organic polyhydroxy compounds, in particular polyetherols, having molecular weights of from 300 to 6000, and, if required, chain extenders and/or crosslinking agents having molecular weights of up to about 400, in the presence of catalysts, blowing agents, flameproofing agents, assistants and/or additives is known and has been widely described. A comprehensive overview of the preparation of polyurethane foams is given, for example, in Kunststoff-Handbuch, Volume VII, Polyurethane, 1st Edition 1966, edited by Dr. R. Vieweg and Dr. A. Höbchtlen, and 2nd Edition, 1983, and 3rd Edition, 1993, each edited by Dr. G. Oertel (Carl Hanser Verlag, Munich).
For various fields of use, in particular the production of upholstered furniture and reclining furniture, for insulation purposes, in vehicle construction and in applications in the medical and hygiene sector, it is frequently desirable to use foams which are extremely soft and at the same time have a high level of mechanical properties.
EP-A-433889 claims flexible foams which have low compressive strength and are based on block polyoxypropylenepolyoxyethylenepolyol mixtures, the content of primary OH groups being from 3 to 8% by weight. U.S. Pat. No. 4,950,695 describes a soft foam, a correspondingly flexible foam being obtained by the use of monofunctional polyetherols. Up to 25% of monools can be used there. EP-A-422080 likewise mentions the use of monofunctional polyols (up to 80%) for obtaining flexible polyurethane foams. EP-A-703254 claims soft foams which are obtained by a polyol combination with the use of chain extenders and primary amines (up to 1% by weight). These hot foams were prepared with an index of about 70 but must be subjected to a heat treatment at relatively high temperatures after production. EP-A-339369 mentions polyetherols having a higher functionality as cell-opening agents and compositions for improving the foam flexibility. The preferred amount for use is up to 5% by weight. In comparison, EP-A-913414 describes very flexible foams which were prepared using nonylphenol-initiated polyol species. An insufficient level of mechanical property is achieved there. EP-A-547764 claims resilient MDI foams, with the concomitant use of ethylene oxide-rich polyols in amounts of up to 30% by weight. EP-A-547765 describes flexible polyurethane foams based on ethylene oxide-rich polyols (>50% of ethylene oxide), a random distribution of the ethylene oxide being present within the polyether chain. The isocyanate used comprises >85% of 4,4′-MDI.
U.S. Pat. No. 4,929,646 describes an ethylene oxide-rich polyol having a high functionality as a cell-opening agent. According to U.S. Pat. No. 3,857,800, up to 15% of ethylene oxide-rich polyols are used in the polyol mixture in order to obtain better cell opening. In WO-A-97/23545, ethylene oxide-rich polyols are used in order to obtain hydrophilic flexible foams. Said polyols have a propylene oxide terminal block, resulting in high proportions of secondary OH groups. U.S. Pat. No. 5,011,908 claims flexible foams which may comprise up to 10% of ethylene oxide-rich polyetherols. Relatively resilient foams are obtained there.
EP-A-731120, EP-A-884338 and DE-A-19508079 describe sorbitol-based polyetherols having a relatively high functionality for the preparation of resilient flexible foams. By using such polyols which carry a terminal ethylene oxide block, the required process safety in the preparation of such resilient flexible foams is achieved. However, the foams thus prepared are relatively rigid. DE-A-19725020 claims resilient flexible foams in which in particular combinations of polyols having a high functionality and an ethylene oxide endcap and polymeric polyols are used. However, substantial rigidity is also obtained in the case of these foams. EP-A-733078 describes resilient foams. Once again, polyetherols having a high functionality are used for the slabstock foams thus produced. The processing latitude is within an index range of from 75 to 120. Ethylene oxide-rich polyols are present as cell-opening agents.
According to EP-A-549120, ethylene oxide-rich polyols and amino-containing chain extenders are used in order to obtain resilient flexible foams. In selected cases—as a rule ethylene oxide-rich polyetherols are also contained in the foam formulation—an attempt is made to establish an insulating character of the foams by special processing, in particular with pronounced undercrosslinking. As a rule, foaming is effected with an index of about 60-80. Thus, DE-A-3710731 describes a flexible foam of this type having sound-insulating and antidrumming properties. It is based on the fact that the elastic properties generally decrease with a decrease in the index.
DE-A-4129666 uses polyols which are incompatible with one another and which slowly separate, in order to establish the acoustic properties. The foams are processed with indices of <80, which can affect the mechanical properties. It is shown that the resilience of the foams decreases with a reduction in the index. Furthermore, the elongation properties deteriorate.
The inventions mentioned in the prior art all permit the preparation of flexible foams having medium hardness, there still being a notable potential for improvement with respect to the properties and the processability in the case of this class of substance.
It is an object of the present invention to provide flexible polyurethane foams which are easy to process, with the use of both tolylene diisocyanate and in particular diphenylmethane diisocyanate isomers, and which are extremely flexible and at the same time have a high level of mechanical properties.
We have found that this object is achieved, surprisingly, by using a polyetherol mixture (b) which consists of at least one polyetherol which is at least difunctional, has an OH number of from 20 to 100 mg KOH/g and is based on propylene oxide and/or butylene oxide and ethylene oxide, having an ethylene oxide content of more than 40% by weight, based on the total amount of alkylene oxide used, and, if required, further at least difunctional polyetherols based on propylene oxide and/or butylene oxide and ethylene oxide and having an OH number of from 20 to 160 mg KOH/g (b1) and at least one difunctional to hexafunctional polyetherol based on propylene oxide and/or butylene oxide and having an OH number of less than 800 mg KOH/g (b2) for the preparation of the flexible polyurethane foams, and preparing the foams with indices of less than 110, the amount by weight of (b1) being greater than that of (b2).
The present invention therefore relates to a process for the preparation of flexible polyurethane foams by reacting organic and/or modified organic polyisocyanates (a) with a polyetherol mixture (b) and, if required, further compounds (c) having hydrogen atoms reactive toward isocyanates, in the presence of water and/or other blowing agents (d), catalysts (e) and, if required, further assistants and additives (f), wherein the polyetherol mixture (b) consists of
b1) at least one polyetherol which is at least difunctional, has an OH number of from 20 to 100 mg KOH/g and is based on propylene oxide and/or butylene oxide and ethylene oxide, having an ethylene oxide content of more than 40% by weight, based on the total amount of alkylene oxide used, and, if required, further polyetherols which are at least difunctional, are based on propylene oxide and/or butylene oxide and ethylene oxide and have an OH number of from 20 to 160 mg KOH/g, and
b2) at least one difunctional to hexafunctional polyetherol based on propylene oxide and/or butylene oxide and having an OH number of less than 800 mg KOH/g
and the foams are prepared with indices of less than 110, the amount by weight of (b1) being greater than that of (b2).
The present invention furth
Baum Lothar
Falke Peter
Schröder Heinz-Jürgen
BASF - Aktiengesellschaft
Borrego Fernando A.
Cooney Jr. John M.
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