Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reissue Patent
2002-03-22
2003-07-22
Cooney, 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...
C521S155000, C521S163000, C521S167000, C521S170000, C521S902000, C528S053000, C528S065000
Reissue Patent
active
RE038201
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not applicable.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not applicable.
BACKGROUND OF THE INVENTION
Polyurethanes are useful in a variety of applications. For example, polyurethane elastomers are used in automative parts, shoe soles, and other products in which toughness, flexibility, strength, abrasion resistance, and shock-absorbing properties are required. Polyurethanes are also used in coatings and in flexible and rigid foams.
Polyurethanes, in general, are produced by the reaction of a polyisocyanate and a polyol in the presence of a catalyst. The catalyst is typically a low molecular weight tertiary amine such as triethylenediamine.
Polyurethane foams are produced through the reaction of a polyisocyanate with a polyol in the presence of various additives. One class of additives which is particularly effective as blowing agents is the chlorofluorocarbons (CFCs). CFCs vaporize as a result of the reaction exotherm during polymerization and cause the polymerizing mass to form a foam. However, the discovery that CFCs deplete ozone in the stratosphere has resulted in mandates for restricting CFC use. Therefore, more efforts have gone into the development of alternatives to CFCs for forming urethane foams and water blowing has emerged as an important alternative. In this method, blowing occurs from carbon dioxide generated by the reaction of water with the polyisocyanate. Foams can be formed by a one-shot method or by formation of a prepolymer and subsequent reaction of the prepolymer with water in the presence of a catalyst to form the foam. Regardless of the method, a balance is needed between reaction of the isocyanate and the polyol (gelling) and the reaction of the isocyanate with water (blowing) in order to produce a polyurethane foam in which the cells are relatively uniform and the foam has specific properties depending on the anticipated application; for example, rigid foams, semi-rigid foams, and flexible forms.
The ability of the catalyst to selectively promote either blowing or gelling is an important consideration in selecting a catalyst for the production of a polyurethane foam with specific properties. If a catalyst promotes the blowing reaction to too high a degree, carbon dioxide will be evolved before sufficient reaction of isocyanate with polyol has occurred. The carbon dioxide will bubble out of the formulation, resulting in collapse of the foam and production of a poor quality foam. At the opposite extreme, if a catalyst promotes the gelling reaction too strongly, a substantial portion of the carbon dioxide will be evolved after a significant degree of polymerization has occurred. Again, a poor quality foam is produced; characterized by high density, broken or poorly defined cells, or other undesirable features. Frequently, a gelling catalyst and a blowing catalyst are used together to achieve the desired balance of gelling and blowing in the foam.
Tertiary amine catalyst have been used to in the production of polyurethanes. The tertiary amine catalysts accelerate both blowing (reaction of water with isocyanate to generate carbon dioxide) and gelling (reaction of polyol with isocyanate) and have been shown to be effective in balancing the blowing and gelling reactions to produce a desirable product. However, typical tertiary amines used as catalysts for polyurethane production generally have offensive odors and many are highly volatile due to low molecular weight. Release of tertiary amines during polyurethane production may present significant safety and toxicity problems, and release of residual amines from consumer products is generally undesirable.
Amine catalyst which contain amide functionality have an increase in molecular weight and hydrogen bonding and reduced volatility and odor when compared to related compounds lacking amide functionality. An advantage of the use of compounds having amide functionality in the preparation of polyurethanes is that the amide chemically bonds with the urethane during the polymerization reaction and thus is not released from the finished product. However catalyst structures which contain both amine and amide functionality typically have low to moderate activity and promote both the blowing and gelling reaction to varying extents.
Examples of patents directed to compounds having both tertiary amine and amide functionallity are described below:
U.S. Pat. No. 3,073,787 (Krakler, 1963) discloses an improved process for preparing isocyanate foams in which catalysts made from 3-dialkylaminopropionamide and 2-dialkylaminoacetamide are used.
U.S. Pat. No. 4,049,591 (McEntire et al., 1997) discloses a group of 1,3-substituted bis-(N,N,-dimethylaminopropyl) amines as catalysts in reaction polyisocyanate with polyols. The substituted group can be cyano, amide, ester, or ketone.
U.S. Pat. No. 4,248,930 (Haas et al., 1981) discloses several tertiary amines catalysts for the production of polyurethane resins. In the example, a mixture of bis (dimethylamino-n-propyl)amine and N-methyl-N′-(3-formylaminopropyl)piperazine is used to form a PVC/polyurethane-foam laminate.
U.S. Pat. No. 4,508,902 (Hasler et al., 1985) discloses combining a polybasic amino compound, such as 3,3′-{[3-(dimethylamino)propyl]imino}bis-propanamide, with a direct or reactive dyestuff for uses in cellulose dyeing applications.
WO 94/01406 (Beller, et al., 1994) discloses a group of chelating agents, such as 3-[3-(N′,N′-dimethylaminopropyl)-N-methyl]propionamide, and 3-[3-(dimethylamino)-propyl]propionamide, suitable for producing paramagnetic complexes which can be used as contrast agents in magnetic resonance diagnosis applications.
EP 799,821 (Gerkin, et al., 1997) discloses amine/amide catalysts, such as the following two compounds,
for formation of polyurethanes. The catalysts are reported to have low fugitivity due to their reactivity with isocyanates.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to the use of the following two compounds as catalysts in the production of polyurethanes: 3-[3-(dimethylamino)propyl]-propionamide (formula I below) and 3,3′-{[3-(dimethylamino)propyl]imino}bis-propanamide (Formula II below).
The present invention is directed to the use of the following two compounds as catalysts in the production of polyurethanes:
3
-{[
3
-(
dimethylamino
)
propyl]amino}
-
propionamide
(
Formula I below
)
and
3
,
3
′
-{[
3
-(
dimethylamino
)
propyl]imino}bis
-
propanamide
(
Formula II below
)
The compound represented by I and II are effective catalysts in the production of polyurethanes in which an organic polyisocyanate reacts with a compound containing a reactive hydrogen, such as, an alcohol, a polyol, an amine or water. They are particularly useful for the gelling reaction in which an organic polyisocyanate reacts with a polyol. Among the advantages provided by the compounds in the production of polyurethanes are:
they are very active catalysts;
they are selective to the gelling reaction, i.e., the reaction between an organic polyisocyanate and a polyol; and
they bind to the urethane, resulting in little or none of the compound being released from the finished product.
DETAILED DESCRIPTION OF THE INVENTION
The compounds of this invention are readily prepared by the Michael addition of an amino functional amine to an acrylamide. The amino functional amine and acrylamide are present in the reaction mixture in molar ratio of from about 1:10 to about 20:1, and preferably at a ratio of 1 to 2 moles amino amine per equivalent of acrylamide. Air is used to saturate the reaction mixture in order to inhibit the free radical polymerization of acrylamide.
The reaction is preferably carried out at atmospheric pressure; however other pressures can be used.
The reaction can be carried out at a temperature ranging from 0 to 130° C.; preferably from 30 to 100° C., and is allowed to run for 0.1 to 100 hours, preferably, 2 t
Carr Richard Van Court
Chen Ning
Listemann Mark Leo
Underwood Richard Paul
Air Products and Chemicals Inc.
Bongiorno Mary E.
Cooney John M.
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