Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
2002-01-30
2004-04-06
Keys, Rosalynd (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S623000, C568S624000, C252S182110, C252S008810, C106S287230, C427S384000, C510S421000, C510S506000
Reexamination Certificate
active
06717019
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to the use of glycidyl ether-capped acetylenic diol ethoxylates, their manufacture, and their use to reduce surface tension in water-based systems.
BACKGROUND OF THE INVENTION
The ability to reduce the surface tension of water is of great importance in the application of waterborne formulations because decreased surface tension translates to enhanced substrate wetting. Examples of such waterborne compositions include coatings, inks, adhesives, fountain solutions, cleaning compositions and agricultural formulations. Surface tension reduction in water-based systems is generally achieved through the addition of surfactants, resulting in enhanced surface coverage, fewer defects, and more uniform distribution. Equilibrium surface tension performance is important when the system is at rest. Dynamic surface tension provides a measure of the ability of a surfactant to reduce surface tension and provide wetting under high speed application conditions, i.e., high surface creation rates.
Surfactants based on acetylenic glycols such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol (1) and its ethoxylates (2) are known for their good balance of equilibrium and dynamic surface-tension-reducing capabilities with few of the negative features of traditional nonionic and anionic surfactants.
Relative to other families of nonionic surfactants, however, these materials have high critical micelle concentrations, making them less efficient in emulsification and solubilization processes. Acetylenic diols and their ethoxylates are relatively inefficient with respect to surface tension reduction, requiring higher use levels to obtain an equivalent reduction in surface tension. They also have limitations with respect to their effectiveness, that is their ability to reduce the surface tension of a formulation to a low value, regardless of the amount of surfactant used. Finally, acetylenic diol ethoxylates are relatively low foam surfactants, and in many applications, for example cleaning formulations, the formation of foam is desirable from both a performance and aesthetic standpoint.
The importance of a surfactant achieving efficient emulsification and solubilization, and low surface tensions at low use levels, and the ability to control the foam characteristics of a surfactant are of considerable industrial importance and are well appreciated in the art. Extensive discussions of the fundamental properties and practical application of surfactants can be found in Rosen,
Surfactants and Interfacial Phenomena, Second Edition
and in
Kirk Othmer Encyclopedia of Chemical Technology
, Fourth Edition, Volume 23, pp 477-541, which are incorporated by reference.
Many surfactants have the ability to emulsify or solubilize otherwise insoluble organic materials in aqueous media. This emulsification or solubilization generally occurs only at concentrations higher than the critical micelle concentration. It is therefore desirable that surfactants have low critical micelle concentrations, because this will lead to more efficient surfactant utilization [Rosen, p 171ff]. Low critical micelle concentrations are also desirable because they lead to diminished skin and eye irritation.
The ability of a surfactant to reduce the surface tension of an aqueous formulation is important in promoting substrate wetting. Two parameters which are important when evaluating the relative ability of a surfactant to provide surface tension reduction are the efficiency and effectiveness of the surfactant. The efficiency of a surfactant can be defined by its pC
20
value:
pC
20
=−log C
20
where C
20
is the concentration in moles/liter of surfactant required to reduce the surface tension of water by 20 dynes/cm. pC
20
provides a means for comparison of the relative amount of surfactant required to obtain a given surface tension reduction. Since the scale is logarithmic, an increase in pC
20
value of 1 corresponds to a decrease by a factor of 10 in the amount of surfactant required to provide a given surface tension reduction.
The effectiveness of a surfactant can be defined by its limiting surface tension (limiting &ggr;) which is the minimum surface tension observed for an aqueous solution of the surfactant, regardless of surfactant concentration. Effective surfactants can provide wetting under challenging conditions such as those presented by low energy or contaminated substrates.
The foaming characteristics of a surfactant are important because they can help define applications for which the surfactant might be suitable. For example, foam can be desirable for applications such as ore flotation and cleaning. On the other hand, in coatings, graphic arts and adhesive applications, foam is undesirable because it can complicate application and lead to defect formation.
There are numerous references that disclose alkoxylated acetylenic diols and their uses including: U.S. Pat. Nos. 3,268,593; 4,117,249; 5,650,543; 6,313,182; JP 2636954 B2; JP 2621662 B2; JP 04071894 A; JP 2569377 B2; JP 09150577 A; JP 04091168 A; JP 06279081 A; JP 03063187 A; JP 2000144026 A and Leeds, M. W.; Tedeschi, R. J.; Dumovich, S. J. Casey, A. W.
I
&
EC Product Research and Development
1965, 4, 237.
SUMMARY OF THE INVENTION
This invention provides glycidyl ether-capped acetylenic diol ethoxylates which act as surfactants for water-based compositions. The glycidyl ether-capped acetylenic diol ethoxylates have the structure:
wherein:
R
1
is hydrogen or a linear, branched, or cyclic alkyl group having from 1 to about 6 carbon atoms;
R
2
is a linear, branched, or cyclic alkyl group having from 1 to about 12 carbon atoms;
R
3
=—CH
2
OR
4
;
R
4
is a linear, branched, or cyclic alkyl, alkenyl, aryl, or aralkyl group having from 2 to about 30 carbon atoms;
(n+m) is an average value from about 1 to about 100; and
(p+q) is an average value from about 0.5 to about 5.
This invention also relates to processes for the manufacture of glycidyl ether-capped acetylenic diol ethoxylates.
Another embodiment of the invention affords water-based compositions containing an organic or inorganic compound, particularly aqueous organic coating, ink, and agricultural compositions, having reduced equilibrium and dynamic surface tension by incorporation of an effective amount of a glycidyl ether-capped acetylenic diol ethoxylates of the above structure.
It is desirable that an aqueous solution of the glycidyl ether-capped acetylenic diol ethoxylates demonstrates a dynamic surface tension of less than 35 dynes/cm at a concentration of ≦0.5 wt % in water at 23° C. and 1 bubble/second according to the maximum bubble pressure method. The maximum bubble pressure method of measuring surface tension is described in Langmuir 1986, 2, 428-432, which is incorporated by reference.
Also provided is a method for lowering the equilibrium and dynamic surface tension of aqueous compositions by the incorporation of these glycidyl ether-capped acetylenic diol ethoxylate compounds.
Also provided is a method for applying a water-based inorganic or organic compound containing composition to a surface to partially or fully coat the surface with the water-based composition, the composition containing an effective amount of a glycidyl ether-capped acetylenic diol ethoxylate compound of the above structure for reducing the dynamic surface tension of the water-based composition.
There are significant advantages associated with the use of these glycidyl ether-capped acetylenic diol ethoxylates in water-based organic coatings, inks, fountain solutions for gravure printing processes, and agricultural compositions and these advantages include: an ability to formulate water-borne compositions which may be applied to a variety of substrates with excellent wetting of substrate surfaces including contaminated and low energy surfaces; an ability to provide a reduction in coating or printing defects such as orange peel and flow/leveling deficiencies; an ability to produce water-borne coatings, fountain solutions and inks which have low volatil
Air Products and Chemicals Inc.
Keys Rosalynd
Leach Michael
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