Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2003-06-11
2004-08-31
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...
C521S133000, C521S137000, C521S159000, C521S160000, C521S174000, C521S904000
Reexamination Certificate
active
06784217
ABSTRACT:
The instant invention relates to a process for making high resilience foams, and to reaction systems that are useful in the said process.
EP-A-0547765 to Bleys et al. discloses a process for making high resilience foams comprising reacting high 4,4′ MDI with an EO-rich polyol. While the foams thus obtained exhibit good properties, the process suffers from two main drawbacks. The first drawback is that this process, if to be used on large scale, necessarily makes use of a full prepolymer having a very high viscosity, rendering it difficult to process. Lowering the level of prepolymerization lead to foams that tend to close. The second drawback is that this process is very sensitive to the presence of a polyol that has an EO content (generally as tipped) from 10 to 20% by weight. This polyol happens to be used in almost all kinds of foams and thus the equipment will always contain some of this polyol. Carrying out the process of this patent thus requires to clean the equipment very thoroughly before use.
U.S. Pat. No. 5,594,097 to Chaffanjon discloses specific polyols, having the structure PO-PO/EO-EO. One example makes use of a mixture of this polyol with an EO-rich polyol; the resulting foam is said to be of poor quality.
WO 94/24183 discloses the preparation of flexible polyurethane foams using a polyisocyanate containing at least 85% by weight of 4,4′-MDI and a polyol composition comprising 25 to less than 50% by weight of oxyethylene groups; prepolymers may be used as well. Only up to 50% by weight of other polyols may be used.
U.S. Pat. No. 5,677,361 to Treboux et al. discloses a process for making high resilience foams comprising reacting an isocyanate with a specific polyol composition, which comprises an EO-rich polyol, a classical polyol comprising tipped EO, and a polymer polyol. This process however uses the EO-rich polyol in minor amounts.
The instant invention aims at solving these problems and at providing a process which is not sensitive to PO-rich polyols (EO contents below 20%) and which is easy to carry out, and at providing reaction systems which are easily processable. The instant invention also aims at providing foams with high resilience and low compression set values, low hysteresis loss (lower than 20%), and with latex-like feel.
The invention thus provides a prepolymer process for preparing a high resilience flexible polyurethane foam at an NCO index of 70-120, preferably 70-110, by reacting:
a) a polyisocyanate composition comprising at least 80% by weight of 4,4′-MDI;
b1) a polyoxyethylene-polyoxypropylene polyol, having an average nominal hydroxy functionality of 2-6, where the EO is present as tipped EO and/or random EO, the total EO content being at least 50% by weight;
b2) a polyoxyethylene-polyoxypropylene polyol, having an average nominal hydroxy functionality of 2-6, where the EO is present as tipped EO and/or random EO, the total EO content being between 20-50% by weight, having a primary hydroxy content of at least 50%;
b3) a polyoxyethylene-polyoxypropylene polyol, having an average nominal hydroxyl functionality of 2-6, having a primary hydroxy content-of at least 50% and having an-EO content of from 10 to 20% by weight;
these polyols b1, b2 and b3 being reacted according to the following proportions, based on the combined weights of b1, b2 and b3, b1: 40-90 wt %, b2: 5-60 wt %, b3: 0-20 wt %;
c) water; and
d) additives and auxiliaries known per se;
and where the polyisocyanate prepolymer has an NCO value below 20% by weight.
The invention also relates to a reaction system comprising A) a polyisocyanate prepolymer obtained by reacting the polyisocyanate with part of the polyol composition of the invention, and B) an isocyanate-reactive component comprising the remainder of the polyol composition of the invention and water.
In the context of the present invention the following terms, if and whenever they are used, have the following meaning:
1) isocyanate index or NCO index:
the ratio of NCO-groups over isocyanate-reactive hydrogen atoms present in a formulation, given as a percentage
[
NCO
]
×
100
[
active
hydrogen
]
(
%
)
In other words the NCO-index expresses the percentage of isocyanate actually used in a formulation with respect to the amount of isocyanate theoretically required for reacting with the amount of isocyanate-reactive hydrogen used in a formulation.
It should be observed that the isocyanate index as used herein is considered from the point of view of the actual foaming process involving the isocyanate ingredient and the isocyanate-reactive ingredients. Any isocyanate groups consumed in a preliminary step to produce modified polyisocyanates (including such isocyanate-derivatives referred to in the art as quasi or semi-prepolymers and prepolymers) or any active hydrogens reacted with isocyanate to produce modified polyols or polyamines, are not taken into account in the calculation of the isocyanate index. Only the-free-isocyanate groups and-the free isocyanate-reactive hydrogens (including those of the water) present at the actual foaming stage are taken into account.
2) The expression “isocyanate-reactive hydrogen atoms” as used herein for the purpose of calculating the isocyanate index refers to the total of hydroxyl and amine hydrogen atoms present in the reactive compositions in the form of polyols, polyamines and/or water; this means that for the purpose of calculating the isocyanate index at the actual foaming process one hydroxyl group is considered to comprise one reactive hydrogen, one primary or secondary amine group is considered to comprise one reactive hydrogen and one water molecule is considered to comprise two active hydrogens.
3) Reaction system: a combination of components wherein the polyisocyanate component is kept in a container separate from the isocyanate-reactive components.
4) The expression “polyurethane foam” as used herein generally refers to cellular products as obtained by reacting polyisocyanates with isocyanate-reactive hydrogen containing compounds, using foaming agents, and in particular includes cellular products obtained with water as reactive foaming agent (involving a reaction of water with isocyanate groups yielding urea linkages and carbon dioxide and producing polyurea-urethane foams).
5) The term “average nominal hydroxyl functionality” is used herein to indicate the average functionality (number of hydroxyl groups per molecule) of the polyol composition on the assumption that this is the average functionality (number of active hydrogen atoms per molecule) of the initiator(s) used in their preparation although in practice it will often be somewhat less because of some terminal unsaturation. The average equivalent weight of a polyol is the average molecular weight divided by this average nominal hydroxyl functionality.
6) The term “average” is used to indicate an average by number.
7) The term “high resilience foams” are intended to designate those foams having a resilience of at least 40%, as measured according to ISO 8307.
The following way of describing polyols is used in the present application: A PO-EO polyol is a polyol having first a PO block attached to the initiator followed by an EO block. A PO-PO/EO polyol is a polyol having first a PO block and then a block of randomly distributed PO and EO. A PO-PO/EO-EO polyol is a polyol having first a PO block then a block of randomly distributed PO and EO and then a block of EO. A PO-EO polyol is a polyol having first a PO block and then an EO block. In the above descriptions only one tail of a polyol is described (seen from the initiator); the nominal hydroxy functionality will determine how many of such tails will be present.
The polyisocyanate used in the prepolymer comprises at least 80% by weight of 4,4′-MDI (methylene diphenyl isocyanate).
The remaining part may comprise isomers thereof, higher functionalities oligomers thereof, variants thereof, or any other isocyanate (such as TDI). The isomers can be 2,4′-MDI and/or 2,2′-MDI. The oligomers are known,
Parfondry Alain
Yu Jianming
Cooney Jr. John M.
Graham Nicole
Huntsman International LLC
LandOfFree
Process for making high resilience foams does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for making high resilience foams, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for making high resilience foams will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3316548