Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-11-12
2001-06-19
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...
C521S129000, C521S155000, C521S163000, C521S164000
Reexamination Certificate
active
06248801
ABSTRACT:
BACKGROUND OF THE INVENTION
Flexible molded polyurethane foam requires mechanical crushing to open the foam cells and prevent shrinkage. Prevention of shrinkage results in improved dimensional stability. Current mechanical methods for cell opening consist mainly of crushing, vacuum rupture or time pressure release. However, these methods usually result in incomplete or inconsistent cell opening and require the foam producer to invest in additional labor and machinery. A chemical method for cell opening which can be incorporated into the foam production process is therefore preferred.
Current chemical methods for cell opening have drawbacks such as requiring high amounts of additive (often as high as 1-5 parts per hundred parts polyol) or adversely affecting the physical properties of the foam. Some examples of current chemical methods for cell opening of polyurethane foam are described below:
U.S. Pat. No. 4,211,849 (Kollmeier et al., 1980) discloses a process for producing an open-celled polyurethane foam by mixing a polyol with a polyisocyanate, a catalyst, a blowing agent, and a crystalline polyhydroxy crosslinker, such as sorbite, mannite, trimethylolmelamine, and glucose, having at least 3 hydroxy groups.
U.S. Pat. No. 4,751,253 (Tylenda, 1988) discloses the use of an additive comprising an ester reaction product of a long chain acid with polyethylene or polypropylene glycols and/or containing free acid to produce an open celled, dimensionally stable, flexible urethane foam product.
U.S. Pat. No. 4,929,646 (Nichols et al., 1990) discloses high molecular weight, high functionality poly(oxyethylene) compounds as cell openers and softeners. The compounds are reported to be highly effective in opening the cells of foam based on PIPA polyols and in softening foams made from MDI-based polyisocyanates.
U.S. Pat. No. 5,039,713 (Petrella, 1991) and U.S. Pat. No. 5,057,480 (Petrella, 1991) disclose blowing reaction catalysts for the production of polyurethane foams. The tertiary amine catalysts consisting essentially of 25 to 80 wt % pentamethyldiethylenetriamine and 20 to 75 wt % bis(dimethylaminopropyl)methylamine are reported to provide cell opening of the foam resulting in improved breathability.
EP 471,260 (1992) discloses a process for the production of open-cell, flexible polyurethane foam in which organic acids, such as benzoic, salicylic, or adipic, or an alkali metal salt of the acid is used as an additive.
U.S. Pat. No. 5,192,812 (Farris et al., 1993) discloses the use of siloxane-oxyalkylene copolymers as cell openers in the production of urethane foams, when employed in combination with silicone surfactants.
U.S. Pat. No. 5,489,618 (Gerkin, 1996) discloses the use of an amine salt, formed by the reaction between a tertiary amine and a carboxylic acid having hydroxyl functional groups, for producing polyurethane foams. The amine salt reportedly produces foams which either are more open or more easily opened, or both, and have a reduced tendency to shrink.
U.S. Pat. No. 5,807,958 (Diblitz et al., 1998) discloses alkaline metal and alkaline earth metal salts of alkyl and alkenyl succinic acids as catalyst for making polyurethane foam. The catalysts are reported to have a favorable influence on the cell structure of the foam.
BRIEF SUMMARY OF THE INVENTION
This invention is directed to a method for making polyurethane foam in which an active methylene or methine compound containing a tertiary amine is used as a cell opening additive. The following advantages are achieved using the cell opening additives of this invention:
the additive is highly effective for polyurethane foam systems based on toluene diisocyanate;
the force to crush values of the foams are dramatically reduced;
the dimensional stability of the foam is improved, thus reducing shrinkage;
the physical properties of the foam are not adversely effected by the additive;
relatively low levels of the additive (0.001 to 2.5 pphp) are needed to create cell opening; and
the additive can also act as a catalyst, due to the presence of a tertiary amine moiety.
For purposes of this invention and as is understood by many in the art, flexible molded foams can include microcellular foams such as those used in shoe soles and steering wheels, as well as the flexible molded foams used in a variety of applications such as furniture, bedding and automotive seating.
REFERENCES:
patent: 4022720 (1977-05-01), Blahak et al.
patent: 4211849 (1980-07-01), Kollmeier et al.
patent: 4751253 (1988-06-01), Tylenda
patent: 4929646 (1990-05-01), Nichols et al.
patent: 5039713 (1991-08-01), Petrella
patent: 5192812 (1993-03-01), Farris et al.
patent: 5489618 (1996-02-01), Gerkin
patent: 5807958 (1998-09-01), Diblitz et al.
patent: 5824711 (1998-10-01), Kimock et al.
patent: 3134592 (1981-09-01), None
patent: 0471260 (1991-08-01), None
Air Products and Chemicals Inc.
Bongiorno Mary E.
Cooney Jr. John M.
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