Low foam N,N′-dialkylmalamide wetting agents

Details Low foam N,N′-dialkylmalamide wetting agents Low foam N,N′-dialkylmalamide wetting agents

2001-03-29

2002-07-02

Clardy, S. Mark (Department: 1616)

Plant protecting and regulating compositions

Plant growth regulating compositions

Designated nonactive ingredient containing

C514S975000, C514S788000, C106S031130, C106S124100, C438S906000, C516S203000, C510S128000

Reexamination Certificate

active

06413914

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to the use of dialkylmalamides to reduce the surface tension in water-based systems.
BACKGROUND OF THE INVENTION
The ability to reduce the surface tension of water is of great importance in waterborne coatings, inks, adhesives, fountain solutions and agricultural formulations because decreased surface tension translates to enhanced substrate wetting in actual formulations. Surface tension reduction in water-based systems is generally achieved through the addition of surfactants. Performance attributes resulting from the addition of surfactants include enhanced surface coverage, fewer defects, and more uniform distribution. Equilibrium surface tension performance is important measure of the ability of a surfactant to reduce surface tension in aqueous systems when the system is at rest.
Traditional nonionic surfactants, such as alkylphenol or alcohol ethoxylates and ethylene oxide (EO)/propylene oxide (PO) copolymers, and anionic surfactants, such as sodium dialkyl sulfosuccinates, have good equilibrium surface tension performance. However, many of these surfactants are foamy and this can lead to problems in applications such as coatings, inks, adhesives, fountain solutions, agricultural formulations, electronic chemicals and cleaning formulations, and other applications where foam can lead to surface defects, poor adhesion, and processing difficulties. Additionally, anionic surfactants can impart water sensitivity to the finished coating.
In addition to the development of high-performance surfactants, there is considerable interest in the industry in surfactants with improved environmental characteristics. Environmental concerns have led to an increased use of environmentally compatible surfactants as alternatives have become available. In addition, the use of less favorable products, such as alkylphenol ethoxylate (APE) surfactants, has declined. This is, in part, due to the poor environmental characteristics of APE surfactants, such as incomplete biodegradation and a suspicion that they may function as endocrine mimics. The demand for high-performance, eco-friendly surfactants has stimulated efforts in new surfactant development. From this work a new family of surfactants, referred to as alkyl polyglycoside (APG) surfactants, has emerged as a readily biodegradable, environmentally-friendly alternative to conventional surfactants. These materials can be foamy and thus are not suitable for many coating, ink, adhesive, fountain solution, agricultural, and electronic chemical and cleaning applications where the generation of foam is undesirable.
Thus, not only is it desirable to obtain surfactants which exhibit excellent surface tension reducing capabilities and low foam, but it is also highly desirable that such new surfactants are environmentally-friendly. Moreover, since there is substantial interest in the development of environmentally-friendly surfactants, an essential attribute would be that these new surfactants not only possess the aforementioned desired performance properties but also are derived from naturally occurring compounds or their synthetic equivalents.
The importance of reducing surface tension in applications such as coatings, inks, adhesives, agricultural formulations, and electronic chemical and cleaning is well-appreciated in the art. The ability to lower the surface tension of aqueous media without producing foam is critical when one wants to wet low energy or contaminated substrates. In J. C. Padget's article entitled “Additives for Water-based Coatings—A Polymer Chemist's View” in
Additives for Water
-
based Coatings,
D. R. Karsa, ed., Cambridge, UK: Royal Society of Chemistry, 1990, pp. 1-29, the importance of surfactants in lowering the surface tension of aqueous systems in order to achieve wetting on low energy materials such as plastics and oily steel is highlighted.
In the graphic arts, it is well-known that surfactants lower the surface tension of aqueous media and thus aid in printing on lower energy substrates such as plastics, coated papers, coated cardboards, and foils and in wetting pigments to produce dispersions. In
Dispersions: Characterization, Testing, and Measurement,
Marcel Dekker, Inc., 1990, there is an entire chapter devoted to the topic of wettability and the necessity of lowering surface tension in order to achieve displacement of air from around small pigment particles and allow wetting and spreading on the pigment surface. Surfactants are known to act as wetting agents to moisten hydrophobic areas of the printing plate in offset printing (R. Kubler, “Printing Inks,” in
Ullmann's Encyclopedia of Industrial Chemistry,
Vol. A22, 1993, pp. 143-156), and certain surfactants have been beneficial in reducing foam generation in the ink fountain in flexographic and rotogravure printing inks (R. W. Bassemir, et al., “Inks,” in
Kirk
-
Othmer Encyclopedia of Chemical Technology,
4
th
Edition, Vol. 14, pp. 482-503).
In addition, the demands of the semiconductor fabrication industry have led to the requirement for high performance surfactants and wetting agents for photoresist developer formulations. As line features shrink to smaller sizes and photoresist substrate materials become more aliphatic in nature (i. e., lower surface energy), aqueous developer solutions increasingly are being formulated with surface tension reducing agents. An additional requirement for these developers, accentuated by the move toward larger wafer sizes, is that they exhibit low foam. This is particularly important when the so-called spray puddle techniques are used in applying the developer solution, wherein the developer is sprayed over increasingly larger areas. Even in cases where puddle or immersion techniques are used, microbubble entrainment during spreading of the solution over the photoresist surface can lead to defects. Other applications in the electronics industry using aqueous processing media would also benefit from good wetting and low foam.
Tetramethylammonium hydroxide (TMAH) is the chemical of choice in aqueous alkaline solutions for developing photoresists according to
Microlithography, Science and Technology,
J. R. Sheats and B. W. Smith, editors, Marcel Dekker, Inc., 1998, pp. 551-553. Surfactants are added to the aqueous TMAH solutions to reduce development time and scumming and to improve surface wetting.
A few examples of amides of malic acid (2-hydroxybutanedioic acid), also called malamides, are known. L-Malic acid occurs naturally as the predominant acid in many fruits, including apples, persimmons, quince and watermelons. It is classified as GRAS (Generally Recognized As Safe) by the U.S. Food and Drug Administration and is commonly used as a food acidulant. L-Malic acid is produced commercially from aqueous fumaric acid using immobilized
Brevibacterium flavum
cells in carrageenan. The racemic form, DL-malic acid, is also known. It is produced by hydration of maleic acid at elevated temperature and pressure.
In the literature, malic acid amides have been reported. However, the ability of malamides to lower surface tension in aqueous media has never been studied or realized.
Dermer and George,
Proceedings of the Oklahoma Academy of Science,
1972, 52, pp. 66-69, describe the preparation of several malamides via reaction of the malate esters with primary amines. Malamides based on ethyl, isopropyl, cyclohexyl, hydroxyethyl and benzyl amines were isolated and characterized.
DE 4424533 A1 broadly discloses oligohydroxy dicarboxylic acid derivatives, including certain malamides derived from fatty alkyl amines, as synthetic barrier lipids in skin care products.
U.S. Pat. No. 5,359,129, discloses many malic acid derivatives, specifically including the acetate of lauryl malamide, and methods for treatment of psoriasis using such compositions.
U.S. Pat. No. 5,776,494 discloses the use of alkyl amides of di- and tri-carboxylic acids as gelling agents in non-aqueous pharmaceutical compositions.
SUMMARY OF THE INVENTION
This invention provides water-based compositions contai

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