Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2002-01-10
2003-01-14
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...
C252S182250, C252S182260, C252S182270, C521S130000, C521S167000
Reexamination Certificate
active
06506813
ABSTRACT:
The instant invention relates to a process for making cold-setting flexible foams. It also relates to a specific polyol composition and to a reaction system that are useful in the said process, as well as to the foams thus-obtained.
Cold-setting flexible polyurethane foams, that are useful e.g. for sound damping, i.e. visco-elastic foams, are known. However, the current processes and foams suffer from drawbacks. Firstly, there is a growing concern regarding the safety, health and environment. The current foams that are used nowadays are manufactured using amine-based catalysts. While these catalysts have proven their usefulness, they exhibit drawbacks such as volatility, resulting in smelling, fogging (fouling of inner glass surfaces, e.g. in automotive vehicles, because of condensation of volatile residues from polymers, etc.), and residual basicity. Secondly, there is a growing concern regarding the handling of the raw materials during the manufacture of the foam. In case of visco-elastic foams, notably those used for sound insulation in automotives, it is customary to use polyols blends. However, the polyols of the blends are often not miscible with each other, thus producing polyols blends that are not homogeneous. Thirdly, current visco-elastic foams, while they exhibit good damping properties, often show a high compression set, which is detrimental to the foam.
Thus, there is still a need for a composition that would produce foams that would meet the requirements of safety, health and environment, i.e. that would require a lower amount of amine catalyst, and that could be produced from more stable, homogeneous, polyol blends and that would show good damping properties together with a low compression set.
U.S. Pat. No. 5,063,253 discloses a process for preparing visco-elastic cold-setting flexible foams that are useful for damping sound comprising reacting a polyisocyanate in the presence of water with a) at least one polyether having an OH value of 20-60, based on propylene oxide (PO) and ethylene oxide (EO), the EO content being 5-25% by weight, b) a polyether or polyester having an OH value of 150-400, and c) a polyether different from a) and b), having an OH value of 20-200, based on PO and EO, the EO content being greater than 50%, where the amount of b) is from 10 to 20% and the amount of c) is 30 to 70%, by weight based on the combined weights of a), b) and c). The catalyst that is used is amine-based, and is used, according to the examples, in amounts from 1.20 to 1.33 parts by weight per 100 parts by weight of the above 3 polyols. EP-A-0 433 878 discloses a process for preparing visco-elastic cold-setting flexible foams that are useful for damping sound, comprising reacting a polyisocyanate in the presence of water with ai) a polyoxyethylene-polyoxypropylene having an OH value of 14-65, a functionality of 2.3-2.8, based on propylene oxide (PO) and tipped ethylene oxide (EO), the EO content being 2-9% by weight, aii) a polyoxyethylene-polyoxypropylene having an OH value of 20-80, based on propylene oxide (PO) and ethylene oxide (EO), the EO content being 60-85% by weight, b) a chain extender having a molecular weight of 18-400, which can be an amine-initiated polyol. The catalyst that is used is amine-based, and is used, according to the examples, in amounts that are at least 1%, by weight, based on the total weight of the reacting composition. The loss factor is said to be between 0.7 and 1.5.
None of the above documents teaches or suggests the instant invention.
The invention thus provides a polyol composition comprising:
b1) a polyoxyethylene-polyoxypropylene polyol, having an average nominal hydroxyl 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 hydroxyl functionality of 2-6 and having a primary hydroxyl content of at least 50%, the EO content being from 10 to 25% by weight;
b3) an amine-initiated polyoxypropylene polyol, having an average nominal hydroxyl functionality of 2-6, and having an OH value greater than 400 mg KOH/g,
these polyols b1, b2 and b3 being present according to the following proportions, based on the combined weights of b1, b2 and b3, b1: 20-70 wt %, b2: 5-50 wt %, b3: 5-50 wt %.
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, if used) 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.
6) The term “average” is used to indicate an average by number.
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 hydroxyl functionality will determine how many of such tails will be present.
The polyisocyanates may be selected from aliphatic, cycloaliphatic and araliphatic polyisocyanates, especially diisocyanates, like h
Parfondry Alain
Yu Jianming
Cooney Jr. John M.
Huntsman International LLC
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