Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2001-11-28
2002-08-13
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...
C252S182260, C252S182270, C252S182240, C521S134000, C521S155000, C521S170000, C521S174000
Reexamination Certificate
active
06433031
ABSTRACT:
This application is the National Phase of International Application PCT/EP00/03932 filed May 2, 2000, which designated the U.S. and that International Application was published under PCT Article 21(2) in English. The PCT application is hereby incorporated in its entirety by reference.
The present invention relates to the field of polymer-modified polyols useful in the manufacture of polyurethane products.
Stable dispersions of particulate material in a high molecular weight polyol are known. These products are referred to as polymer-modified polyols or polymer polyols. One class of such polymer polyols is known as polyisocyanate polyaddition polyols (or PIPA polyols). They are the dispersion, in a high molecular weight polyol, of the reaction product of a polyisocyanate and a low molecular weight polyol.
GB-A-2 102 822 discloses such PIPA products, where the low molecular weight polyol is an alkanolamine, especially triethanolamine (TELA). While these products are adapted for the production of flexible foams, they suffer from drawbacks. The first drawback is the costs associated with TELA, which is an expensive product. The second drawback is the fact that the final product may not show sufficient load-bearing properties, since not all hydroxy groups of TELA may react with the isocyanate.
Similar problems occur with other alkanolamines, such as diethanolamine (DELA).
Diethyleneglycol (and other ethyleneglycol derivatives) is also known as a low molecular weight polyol used in preparing PIPA polyols, as is disclosed in EP-A-0 072 096. However, it suffers from drawbacks. The drawback is that DEG is to a higher extent soluble in high molecular weight polyol, providing solutions rather than dispersions. As a result, this often leads to solid PIPA products which remain solid despite heating.
It has been surprisingly found that flexible foams, having improved load-bearing properties, can be obtained from a polymer-modified polyol which is liquid (at room temperature) and where the low molecular weight polyol is a mixture of e.g. TELA or DELA with DEG.
Thus, the invention provides a polymer-modified polyol which is a high molecular weight polyol comprising dispersed therein the reaction product of a polyisocyanate and a low molecular weight polyol where said low molecular weight polyol is a mixture of an alkanolamine with a polyethylene glycol having a molecular weight of less than 600.
The invention also provides a process for making a flexible foam using the polymer-modified polyol of the invention, the thus-obtained foams, and a reaction system comprising the polymer-modified polyol.
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.
By the term “polymer-modified polyol” is meant a polyol containing additional polymeric material dispersed in it. This term is understood by those skilled in the art and is used, for example, in EP-A-0 072 096.
The high molecular weight polyol used in the invention may be any of the polyols, or mixtures thereof, used in the manufacture of polyurethanes, having an average hydroxyl equivalent weight of at least 500. These polyols can be polyether polyols, polyester polyols, polyesteramide polyols, polythioether polyols, polycarbonate polyols, polyacetal polyols, polyolefin polyols, and the like.
Polyether polyols, which may be used, include products obtained by the polymerization of a cyclic oxide, for example ethylene oxide, propylene oxide, butylene oxide or tetrahydrofuran in the presence of polyfunctional initiators. Suitable initiator compounds contain a plurality of active hydrogen atoms and include water, butanediol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, dipropylene glycol, ethanolamine, diethanolamine, triethanolamine, toluene diamine, diethyl toluene diamine, phenyl diamine, toluene diamine, phenyl diamine, diphenylmethane diamine, ethylene diamine, cyclohexane diamine, cyclohexane dimethanol, resorcinol, bisphenol A, glycerol, trimethylolpropane, 1,2,6-hexanetriol, pentaerythritol, sorbitol and sucrose. Mixtures of initiators and/or cyclic oxides may be used.
Especially useful polyether polyols include polyoxypropylene diols and triols and poly(oxyethylene-oxypropylene) diols and triols obtained by the simultaneous or sequential addition of ethylene and propylene oxides to di- or trifunctional initiators as fully described in the prior art. Random copolymers having oxyethylene contents of 10-90%, block copolymers having oxyethylene contents of up to 50% and random/block copolymers having oxyethylene contents of up to 90%, based on the total weight of oxyalkylene units may be mentioned in particular those having at least part of the oxyethylene groups at the end of the polymer chain. Mixtures of the said diols and triols can be particularly useful. Other particularly useful polyether polyols include polytetramethylene glycols obtained by the polymerization of tetrahydrofuran.
A preferred polyol is a poly(oxyethylene-oxypropylene) polyol having EO as tipped EO with an EO content from 5 to 30%, preferably 10 to 25%, on a weight basis of total oxyalkylene groups. One other preferred polyol is a poly(oxyethylene-oxypropylene) p
Cooney Jr. John M.
Huntsman International LLC
Pillsbury & Winthrop LLP
LandOfFree
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