Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2000-05-24
2001-03-13
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S137000, C521S914000, C521S161000, C521S112000
Reexamination Certificate
active
06201035
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to a method for producing slabstock polyurethane foams and, more particularly, to the use of a polyol blend including a conventional unsaturated polyol, a graft polyol, and a very low unsaturated polyether polyol for the production of slabstock polyurethane foams.
Polyols are generally defined as compounds that include a plurality of hydroxyl groups. Polyols having at least two isocyanate-reactive hydrogen atoms, particularly polyether polyols, are useful when combined with polyisocyanates to form polyurethanes. Polyols can be combined with polyisocyanates in the presence of catalysts and blowing agents to form either rigid or flexible foams. Flexible polyurethane foams are distinct from rigid foams. Flexible foams typically have a limited resistance to an applied load, are open-celled, permeable to air and are reversibly deformable. Flexible foams can either be formed in a discontinuous molding process or through a continuous slabstock process. In the continuous slabstock process, typically, the components are rapidly mixed together and extruded onto a moving bed reactor where the foam is permitted to freely rise to its final height. After the foam has fully risen it is processed to the desired final dimensions. Flexible foams are particularly useful in seating applications, carpet padding and other applications requiring reversible deformation of the foam.
Two important properties of flexible slabstock foam are its indentation force deflection and resilience. Many current flexible slabstock foam formulations suffer from less than ideal indentation force deflection and resilience properties. It would be advantageous to provide a flexible slabstock formulation having improved indentation force deflection and resilience properties
SUMMARY OF THE INVENTION
In general terms, this invention provides a method for making a flexible slabstock polyurethane foam using a polyol blend including a conventional unsaturated polyether polyol, a graft polyether polyol, and a very low unsaturated polyether polyol. The foam produced by the method has substantially improved indentation force deflection and resilience properties while maintaining the other physical properties of the foam when compared to foam made without the very low unsaturated polyether polyol. These improved properties greatly enhance the foam's loadbuilding characteristics.
In one embodiment, the present invention is a method for the formation of a slabstock polyurethane foam comprising the steps of forming a polyol blend having a nominal functionality of at least 2.3 by combining the following: at least one polyether polyol having a plurality of terminal ethylene oxide caps of from 5 to 25% by weight based on the total weight of the polyether polyol, a molecular weight of greater than or equal to 4000 Daltons, and an unsaturation of greater than 0.04 meq/g KOH; at least one graft polyether polyol having an equivalent weight of greater than 1000 Daltons, a solids content of at least 28%, and a plurality of terminal ethylene oxide caps of from 5 to 25% by weight based on the total weight of the graft polyether polyol; and at least one very low unsaturated polyether polyol having an unsaturation of less than or equal to 0.018 meq/g KOH and a plurality of terminal ethylene oxide caps of from 5 to 25% by weight based on the total weight of the polyether polyol. Additional steps comprise providing at least one polyisocyanate component; providing a catalyst; providing water as a blowing agent at a level of between 3 to 7% by weight; and combining the polyol blend with the polyisocyanate component, the catalyst and the water to form a slabstock polyurethane foam.
In another embodiment, the invention is a slabstock polyurethane foam comprising the reaction product of: a polyether polyol blend having a nominal functionality of at least 2.3 and comprising at least one polyether polyol having a plurality of terminal ethylene oxide caps of from 5 to 25% by weight based on the total weight of said at least one polyether polyol, a molecular weight of greater than or equal to 4000 Daltons, and an unsaturation of greater than 0.04 meq/g KOH; at least one graft polyether polyol having an equivalent weight of greater than 1000 Daltons, a solids content of at least 28%, and a plurality of terminal ethylene oxide caps of from 5 to 25% by weight based on the total weight of said at least one graft polyether polyol; and at least one very low unsaturated polyether polyol having an unsaturation of less than or equal to 0.018 meq/g KOH and a plurality of terminal ethylene oxide caps of from 5 to 25% by weight based on the total weight of said at least one polyether polyol; and a polyisocyanate component in the presence of a catalyst, water at a level of between 3 to 7% by weight as a blowing agent, and optionally, one or more surfactants.
Polyurethane foams produced using the method of the present invention have substantially improved indentation force deflection and resilience characteristics compared to a foam made with a similar polyol blend without the very low unsaturated polyether polyol. The improved properties do not come at the expense of other physical characteristics of the foam, these are maintained.
These and other features and advantages of this invention will become more apparent to those skilled in the art from the following detailed description of the presently preferred embodiment.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
The flexible slabstock polyurethane foams of the present invention are prepared by combining a polyol blend comprising a conventional polyether polyol, a graft polyether polyol and a very low unsaturated polyether polyol with an isocyanate component in the presence of a catalyst and water as a blowing agent. The foams optionally include other additives such as, for example, surfactants, chain extenders/crosslinkers, surface-active substances, flame retardants, and fillers.
Methods of forming conventional and very low unsaturated polyether polyols are well known, for example, by the base catalyzed addition of alkylene oxides to an initiator molecule or nucleus containing reactive hydrogens such as a polyhydric alcohol. In one embodiment of the present invention the initiator nucleus is a triol. Examples of such initiators include: glycerol; 1,1,1-trimethylolpropane; 1,1,1-trimethylolethane; 1,2,6-hexanetriol; pentaerythritol; and sorbitol. Other suitable initiators include both aliphatics and aromatics, such as ethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol. Also included within the term “polyhydric alcohol” are compounds derived from phenol such as 2,2-bis(4-hydroxyphenyl)propane, commonly known as Bisphenol A. The polyether polyols may be prepared by any known process such as, for example, the process disclosed by Wurtz in 1859,
Encyclopedia of Chemical Technology,
Vol. 7, pp. 257-262, Published by Interscience Publishers, Inc. (1951) or in U.S. Pat. No. 1,922,459.
Examples of useful alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, amylene oxide, mixtures thereof, tetrahydrofuran, alkylene oxide-tetrahydrofuran mixtures, epihalohydrins, and arylalkylene styrene. The alkylene oxides are added onto the initiator molecule and chain propagation is carried out in the presence of catalysts by either anionic polymerization or by cationic polymerization.
The preferred catalysts are potassium hydroxide, sodium hydroxide, alcoholates of potassium hydroxide, alcoholates of sodium hydroxide, cesium catalysts, amines, Lewis acid catalysts, or double metal complex catalysts, all of which are known in the art.
Polyols useful in the present invention generally comprise polyether polyols that may have the structure of a plurality of internal blocks formed from oxyalkylenes attached to an initiator molecule. The internal blocks may include any of the above referenced oxyalkyle
Fishback Thomas L.
Lee Thomas B.
Reichel Curtis J.
Tuinman Roeland
Bagwell Melanie D.
BASF Corporation
Borrego Fernando A.
Seidleck James J.
LandOfFree
Use of low unsaturated polyether polyols in high resilience... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Use of low unsaturated polyether polyols in high resilience..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Use of low unsaturated polyether polyols in high resilience... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2456420