CA2011191A1 - Wetting agent for agricultural and plant growth media - Google Patents

Abstract

ABSTRACT

The invention relates to novel compounds characterized by improved ability to wet plant growth media, both soilless and soil-containing, and by less toxicity to the plants which are grown in the mixtures treated with these wetting agents and to methods for their use.

Description

2011~91 WETTING AGENT FOR AGRICULTURAL AND PLANT GROWTH MEDIA

The present invention relates generally to compounds useful as wettinq agents for s~illess mixtures to improve the water penetration, absorption and retention properties thereof for use in agricultural and horticultural industries. More specifically, the invention relates to novel compounds characterized by improved ability to wet soilless mixtures, improved stability and by less toxicity to the plants which are grown in the mixtures treated with these wetting agents.

Backaround of the Invention Wetting agents, or surfactants have been used to treat a variety of organic or synthetic plant growth media, particularly growth media composed primarily of aoilless materials, such as peat or bark. These surfactants are employed to increase the ability of the plant growth media to be uniformly penetrated by water and absorb and retain moisture. See, e~g., U.S. Patent 2,867,944. Surfactants or wetting agents also enhance the ability of plant growth media to drain excess water ~rom the media. Such wetting agents have recently been employed in the maintenance of sports fields, turf and golf courses, as well as for the traditional uses in horticultural and agriculture.

20111~1 A variety of compounds selected from the class of mono-, di- and trialkyl phenol ethylene oxide condensates, have been used as wetting agents. For example, Rainbow, U. S. Patent 4,404,013 describes a plant growth medium comprising peat and a wetting agent which is an alkylene oxide condensate of a tri (alkyl)substituted phenol or a salt or an ester thereof.
Each alkyl substitution may be the ~ame or different and is a straight or branched alkyl group of from 1 to 12 carbon atoms. The preferred alkyl group contains less than 8 carbon atoms, especially 2-6 carbon atoms. There are preferably 6-10 ethyoxylate groups. A tri (butyl) substituted phenol condensate with ethylene oxide is shown in the examples.
Wahlberg, U. S. Patent 3,231,365 refers to a plant growth composition comprising a fertilizer and an organic nonionic wetting agent and which may also include peat or kieselguhr. The wetting agent may be a compound of the formula: R-O-(CH2CH2O)820CH2CH2OH, where R is an aralkyl group having a straight or branched chain hydrocarbon group of 8 to 18 carbon atoms attached to the aryl nucleus and attached to -O- through the aryl nucleus.

201119~

British Patent 1,420,522 di6closes a soilless plant growth medium containlng, as a wetting agent, an alkyl phenol condensate with 8.5 mols of ethylene oxide, the alkyl group containing 8-9 carbon atoms.
British Patent 1,375,829 discloses a soilless plant growth medium containing a non-ionic wetting agent, such as a condensate of nonyl phenol with 9 mols of ethylene oxide.
Nunn et al, U. S. Patent 3,317,612 discloses biodegradable surface active agents, including wetting agents, obtained by the ethoxylation of the product resulting from the reaction of phenol and an excess of butene-2, which reaction product includes di-secondary butylphenol, among other substituted phenols ethoxylated with 9 mols of ethylene oxide.
Kistner, U. S. Patent 3,805,532 pertains to the stabilization or consolidation of aggregate materials for soilless planting media purposes and discloses the use of a surfactant to insure the complete wetting of the aggregate particles. Polyoxyethylene derivatives of arylhydroxy compounds are among the surfactants shown.
Sterrett U. S. Patent 4,067,716 and Webb et al.
U. S. Patent 4,174,957 relate to manufactured soilless growing media which may include wetting agents.

~11191 There remains a need in the art for additional compositions and methods for improving the moisture penetration, retention, and absorption of soilless mixtures used to support the growth of plants and crops, which provide less of a health hazard to the plant itself.

Summary of the InventiQn The present invention involves the unexpected discovery that a class of compounds exist which demonstrate surprising advantages as wetting agents for ~oil~ess mixtures of plant growth media in comparison to known compounds for that use. The invention provides condensates of dialkyl phenol with from 5 to 16 mols of ethylene oxide, with each alkyl group on the phenol containing from 5 to 7 carbon atoms. This group of compounds, as a whole, provides significant advantages over the compounds disclosed in the art, such as the condensates of 9 mols of ethylene oxide with di-secondary butylphenol; with nonyl phenol and with tributyl phenol described in the references above.

2011~91 In one aspect, therefore, the present invention provides a clas~ of compounds compri6ing ethoxylated diC5 7alkyl phenols, according to the following rormula:
~H3 ~ (ocHzcH2)noH
CH3 -~HCH2CH2 ~ CHzCH2CH-CH3 wherein the ethoxylate chain has between 5 and 16 mols ethoxylate units. A desirable class of such agents contains between 7 and 11 mols ethoxylate units. The presently preferred material is a compound derived from 2,4-ditert-amyl phenol having an average of nine mols ethoxylate units.
As another aspect, the invention provides a wetting agent or surfactant composition comprising an ethoxylated diCs7alkyl phenol, having 5 to 16 mols ethoxylate units in association with a suitable carrier.
As 6till another aspect, the invention provides a wetting agent or surfactant composition comprising a mixture of two or more ethoxylated diC57alkyl phenols, having an average of 5 to 16 mols ethoxylate units in a suitable carrier.
A further aspect o~ the present invention provides a method for treating soilless materials to enhance the wettability thereof and provide substantially improved safety to the growth of plants therein. The method involves applying to a soilless mixture an effective amount of a wetting composition described above. An effective amount, for purposes of this process comprises about one to about five ounces per cubic yard of the soilless materials.
As a wetting agent or surfactant composition for soilless plant growth media, the compounds of the present invention are characterized by improved ability to wet the growth media, providing to it enhanced moisture distribution, penetration, and absorption. The compositions of this invention are further characterized by improved stability upon storage, in comparison with known wetting agents. Additionally, the compounds of the present invention demonstrate improved safety to growing plant materials when used to wet plant growth media.
These compounds are less ~amaging and less toxic to the plants grown in media treated with these compounds than in media treated with other known wetting agents.
Other aspects and advantages of the present invention are described further in the following detailed description of preferred embodiments of the present invention.

Brief ~escription of the Drawinqs Figs. 1 through 6, described more specifically below, are graphs which plot the wetting curves of an illustrative compound of this invention, ACA0160, which contains a 2,4-ditert-amyl phenol having an average of nine ethoxylate substituents, compared to those of known wetting agents, when tested in a compacted peat medium.
The ordinates of the graphs in Figs. 2-6 plot the Percent of Control. As defined herein, the Percent of Control is a value expressed as a percentage of the average time in seconds re~uired to fully hydrate a measured volume of compacted peat with a specific concentration of a wetting agent as compared with the time required with water containing no wetting agent. The abscissa of the graph plots the concentration of the compound applied per cubic yard. These graphs and figures are described further in Example 2 below.
Fig. 1 illustrates a wetting curve of ACA0160 and AquaGro-L, plotting time in seconds vs.
concentration.
Fig. 2 illustrates three separate trials ~marked by a square, a cross, and a diamond) of ACA0160 and an average curve (marked by a triangle) generated by tho~e trials.

Fig. 3 ~llustr~tes comparative wetting curves of three compounds: ACA0160 (square), diamyl phenol with 8iX mols ethoxylate units (cross), and diamyl phenol with 12 mols ethoxylate units (diamond~.
Fig. 4 illu~trates comparative wetting curves of four compound~: ACA0160 ~square), 2,4-ditert-butyl phenol with 9 mols ethoxylate units (cross), disec-butyl phenol with 9 mols ethoxylate units (diamond), and 2,6-ditert-butyl phenol with 9 mols ethoxylate units (triangle).
Fig. 5 illuctrates comparative wetting curves of three compounds: ACA0160 (square), butyl phenol with 9 mols ethoxylate units (cross) and nonylphenol with 9 mols ethoxylate units (diamond).
Fig. 6 illustrates ~ wetting curve of a second ~ource of nonylphenol with 9 mols ethoxylate units (~quares).

~Detailed Description o~ the Invention The compound~ of thi6 invention may be de~cribed by reference to the formula appearing below:
~ ( OCH2CH2 ) nOH
R1~--R2 P 20111gl in which n is an integer of between 5 to 16, R1 is the same as R2 or a lower alkyl containing from 5 to 7 carbon atoms, and R2 is a lower alkyl containing from 5 to 7 carbon atoms. For example, such compounds as 2,4-ditert-amyl phenol, dihexyl phenol, diheptyl phenol, 2,4-diamyl phenol, 2,4-disec-amyl phenol and 2,4-ditert-hexyl phenol having ethoxylate groups of between 5 and 16 mols are provided by this invention.
Preferred compounds according to this invention are characterized by the presence of 7 to 11 mols ethoxylate units. A presently most preferred compound is characterized by 9 mols ethoxylate units. Preferred compounds are also characterized by R1 and R2 being identical amyl alkyl groups.
These compounds are prepared by the conventional base-catalyzed epoxide reaction, as described below in Example 1. The method of calculating the mols of ethoxylate units on the desired compound is the conventional method referred to as AOCS Method CD 13-60. Thi6 method is known to one of skill in the chemical arts and is described in detail in Example 1 below.
For use in a wetting agent or surfactant composition, the compounds of the present invention may be used singly or as a mixture of compounds, having average ethoxylate units in the ranges described above.

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Whether used as a single compound or a mixture of compounds as described above, the presently preferred number of average mols ethoxylate units is between 7 and 11, and most preferably 9.
The wetting agent compositions of the present invention can be prepared in either liquid or dry formulations. For use in a liquid formulation, the pure compound can be diluted to an acceptable concentration with water. However, granular formulations of these wetting agents may also be prepared by adsorbing the compounds to a carrier, such as vermiculite or other conventional dry agricultural carrier. The preparation of a dry composition involves conventional techniques, such as blending the compound with the carrier in a blender so that the compound absorbs to the dry carrier.
This type of technique and other techniques for preparing dry formulations of the wetting agent are known to those of skill in the art.
For use in the liquid wetting agent compositions, a preferred concentration of compound to water i6 between approximately 300 to 3000 ppm. For example, that range is acceptable for a preferred compos$tion, ACA0160, a mixture of 2,4-ditert-amyl phenol having an average of 9 mols ethoxylate units. This wetting agent performs well when present in water at 10 ~ 2~11191 to 3000 ppm. For a dry composition, the compounds or mixtures thereof are desirably present in the dry carrier at concentrations of between approximately 15 to 40%, and more preferably at 40%. However, the concentrations of the compounds in the selected liquid or dry carrier may be easily determined by one of skill in the art for the particular application. This invention is not limited to any precise concentrations defined herein, but encompasses all concentrations, which may vary based on the type of soil or soilless material being wetted.
The wetting agent compositions according to the present invention may be applied to the plant growth media as liguids or solid granular form by conventional means, ~uch as spraying, depending on the amount of media to be wet. Generally, the concentration of wetting agent according to this invention per size of media is approximately 1 to 5 ounces per cubic yard, or approximately 100 to 1500 ppm per cubic yard. This application may also change based on the composition of the growth media, e.g., peat, bark, turf, sandy soil, and the like.
The compounds of the present invention are characterized as surprisingly advantageous wetting agents for use on soilless plant growth materials or in soils substantially contaminated with sand or other non-soil ~ 2~11191 suhstances. In contrast to known wetting agents for similar uses, the compounds of this invention demonstrate a more efficient wetting time on such mixtures, such as peat, peat-lite and bark mixes used for the production of greenhouse crops and synthetic soil replacement materials. They may alsQ be used in natural soils, particularly turf soils as well as æoils used to grow woody ornamental trees and shrubs. The Examples below illustrate the improved "wettability" of illustrative compositions of the present invention in comparison to known wetting agent compounds.
An additional advantage of the present invention lies in its improved safety upon exposure to plants. The compounds of the present invention are shown to cause very little damage to plants, as is illustrated by root growth studies, and studies of the compound's effect, or lack thereof, on other observable morphological characteristics of plants grown in soilless media treated with compounds of this invention, as compared with other known wetting agent compounds.
Still a further advantage of the compounds described herein is an enhanced stability of these compounds in storage. This advantage relates primarily to the ability to transport and store the compounds under a variety of conditions without danger of the compounds 2~

becoming unstable and losing their advantageous properties.
The compounds and wetting~surfactant compositions containing these compounds may also find application in other industries, such as asbestos remo~al.
The examples below illustrate the preparation of the compositions of this invention, and their advantages.

E~mple 1 - Pre~aration of a Compound of this Invention The presently preferred compound of the present invention is 2,4-ditert amyl phenol having an average of 9 mols ethoxylate units on the phenol. This compound is prepared by the conventional reaction of base catalyzed lS cleavage of epoxides. Essentially, to prepare 10,000 pounds of the 2,4-ditert amyl phenol having an average of 9 mols ethoxylate units, 3,698 pounds of 2,4-ditert-amyl phenol is introduced into a charging vessel. Into this charging vessel is introduced approximately 6,258 pounds o~ ethylene oxide. Potassium hydroxide is used as a catalyst at a concentration of 0.1%. The reaction is allowed to continue for approximately 4 to 8 hours at approximately 140 to lS0C. One of s~ill in the art may prepare larger or smaller amounts of the compounds of ?J01~191 this invention by reducing the amounts of reactants proportionally.
After the reaction ceases, the resulting average ethoxylation of the resulting compound is established according to the American Official Chemical Society (AOCS) Official Method Cd 13-60. This method is a well known method to chemists and others of skill in the art.
To produce similar compounds of the present invention, having average ethoxylations of between 5 to about 16 mols ethoxylate units, the above reaction is carried out by varying the amounts of the reactants. One of skill in the art following the above teachings could produce such similar compounds.
ACA0160 is employed as the pure compound in all of the remaining examples to illustrate the advantages of compounds of this invention over known wetting agents.
Also employed in these comparative tests is the industry standard wetting agent, called AquaGro-L, commercially available from Aquatrols, Inc., Pennsauken, New Jersey.
This compound is not a dialkyl phenol, and is therefore les6 similar to the compounds of this invention than the other known wettlng agents. However, it is included in the tests because it is a wetting agent of choice in the industry for plant growth media. The following tests 2011~91 demonstrate the superior advantages attaching to the compounds of this invention, even in contrast to the industry ~tandard.

~xample 2 - Wettina Speed Test To evaluate the Qpeed of wetting of various wetting agents including an illustrative compound of the present invention, each compound is prepared in the following concentrations in water. For convenience in charting the efficacy of these compounds in the wetting test system described herein, the numbers along the abscissa of the graphs in Fig. 2-6 were arbitrarily asaigned to represent the following concentrations per cubic yard. These numbers are charted in Table 1 below:
Table 1 NumberConcentration (~m) O O

2~11191 Fifty milliliters o~ each solution is placed in a standard petri dish containing a compressed peat disk, commercially available as a Jiffy 7 ~Jiffy Products (NB), Ltd, Canada3.
In this test the time in seconds required to fully hydrate a measured volume sf compacted peat is determined at various concentrations of wetting agent.
Results are shown in Fig. 1 which shows wetting curves for ACA0160 and AquaGro-L [Aquatrol, Inc.] in a compacted peat medium. The value for the control (no wetting agent, not shown) is >900 seconds.
ACA0160 outperformed AquaGro-L at all rates tested. Of particular note is the fact that the inflection point (point at which the slope changes) of - 15 the wetting curve for ACA0160 was lower than 1 ounce/yd3, while that for AquaGro L was between 667 and 88~ ppm ~4.5)ounces/yd3. These results show that ACA0160 is not only a much faster wetter than AquaGro-L, the industry ~tandard, but also that it is effective at much lower concentrations.
Figs. 2-6 are results of identical tests with other commercially available wetting agents, or with compounds described in thé prior art. These figures demonstrate that ACA0160 is a superior wetting agent.

Based on these teæts, Table 2 below rates the ability of known surfactants to wet peat.

Table 2. Ability of Various Surfactants to Wet Peat 0 = best; 9 = worst; EO - ethoxylate unit Fig./Curve Identi~y _ atina -- Ditert Butyl Phenol (14 EO) 6 1 AquaGro-L 6 3 (cross) Diamyl Phenol (6 E0) 3 (diamond) Diamyl Phenol (12 E0) 2-3 4 (cross) 2,4-Ditert-Butyl Phenol (9 EO) 4-5 4 (diamond) Disec 8utyl Phenol (9 E0) 4-5 4 (triangle) 2,6-Ditert-Butyl Phenol (9 E0) 5 Example 3 - Plant/~rop Safety Evaluation ACA0160 has been evaluated both foliarly and in a wide variety of peat and bark mixes for its effects on plant growth.
A. In the following test where ACA0160 was compared with AquaGro-L for plug production. The rates selected for AquaGro-L exceed the manufacturer's recommendations.

~ 2011191 In this test plug mixes of commercial bark and peat were treated with the level of AquaGro-L or ACA0160 indicated in Table 3 below and given to a commercial grower for evaluation. Except for the differences in the wetting agent, no other cultural practices were changed.
All mixes wet easily except for the control which was heavily misted to insure a moisture content equivalent to the treated mixes.
Of the five species evaluated in this test only Impatiens and Begonia, which are known sen~itive plant species, responded and then only at the 1500 ppm rate of AquaGro-L [recommended rate is between 667-833 ppm (approximately 4.5 ounces)/yd3 for plug production]. No adverse effect on germination or seedling morphology (including roots) was observed for ACA0160 at any concentration tested. Thus, depending upon the rate used, ACA0160 can be expected to have a 3 to 9 fold safety factor for wetting agent sensitive species, such as Impatiens or Begonias. Results are shown in Table 3.

~ 201~191 Table 3. Comparative Ef fect on Plant Growth of Two Growth Media Wetting Agents used in Plug Production 0 = no effect; 9 2 severely inhibited or dead Treatments (ounces/Yd3) SpeciesControl ~Ç~m ÇQ ~quaGro-L
(no wetting agent~ ~ 9 3 9 Percent_Germination Impatiens85 85 85 85 45 Marigold 95 90 95 90 90 Begonia 80 85 85 80 40 Tomato 95 95 95 95 95 Pepper 90 95 90 95 90 Phyto~oxicity Impatiens 0 0 0 0 6 Marigold 0 0 0 0 0 Begonia 0 0 1 0 7 Tomato 0 0 0 0 0 Pepper 1 0 0 0 0 B. In a second phytotoxicity test, the inherent phytotoxicity of ACA0160 was determined in comparison with AquaGro-L. In this test, sheets of filter paper are placed in petri dishes. Seven ml of solution of the concentrations indicated in Table 4 are added and ten seeds of Impatiens are sown on the moietened ~ilter paper. The dishes are then covered. In this test, the wetting agent remains in solution so that the seed and seedling are in intimate contact with the ~ 201119~

free surfactant. The results of the test are described in Table 4 which illustrates that Impatiens were less sensitive to free ACA0160 than to free AquaGro-L.

Table 4. Effect of Free Wettinq Agent on Root Growth of Impatiens Grown on Moistened Filter Paper Concentration (pp~ Root Lenath (cm~
AquaGro-L ACA0160 0 (Control, no wetting agent) 22 C. ACA0160 was also eva~uated as a foliar application in comparison with AquaGro-L. In this test plants were sprayed at the rate indicated in Table 5 and observed at 24 and 96 hours for signs of foliar damage.
ACA0196 tTricol 6972, Emery Chemical Co.] is a good wetting agent which demonstrates phytotoxicity to plants, like many surfactants. ACA0196 which had similar wetting characteristics as ACA0160, was included in this test for comparative purposes.

Neither AquaGro-L or ACA0160 had a significant adverse effect on foliage. ACA0196 as the positive control gave results typical of phytotoxic surfactants.

Table 5. Comparative Foliar Toxicity of Three Surfactants 0 = no effect; 9 = dead Rate (ounces/1000 ft) Impatiens Pepper RyeGrass 10AquaGro-L

4 o 0 0 8 o 0 0 16 9 9 g 25Control 0 0 0 Example 4 - Evaluation Qf Storaae Stability in Soilless Media ACA0160 was evaluated for storage stability in comparison with AquaGro-L. Peat moss treated with either (3 ounces)/yd3 of ACA0160 or (9 ounces)/yd3 of AquaGro-L
were prepared and placed in Zip-Lock bags. Half of the baga were left open to simulate an opened bale, or media placed in growing containers but not in use. The closed bags represented a sealed 201~19~

container as it might come from the manufacturer. At weekly intervals an open and closed bag were selected for each treatment and were evaluated for wettability by percolation tests.
In the percolation test, 200 cc of peat or media are placed in an inverted tube with a screen on the bottom, and 200 ml of water are added. The milliliters of water absorbed and the percent of peat or media wet are then determined. Moisture loss was monitored throughout the course of the experiment in both open and closed bags. The open bags lost moisture quickly but did not stabilize until week ll, after which little or no more drying occurred. The closed bags also lost moisture, but at a much slower rate. However, by week 29 - 15 both open and cloeed bags had the same moisture content (12%). These results are illustrated in Table 6.

* 2011191 Table 6. ACA0160 and AquaGro-L Storage Stability Study for Ease of Wetting in Open and Closed Bags Storage Time %_Wet ~200/200 Percolation Test~

5~Weeks~
ACA0160 AquaGro-L3 (3 ounces/yd3~ Is ounçes~yd ) Open Closed Open Closed 2 100 lOO 9o 100 4 90 100 9~ 90 29* 50 50 10 10 * At 29 weeks, moisture content of open or closed bags was approximately equal.

This gradual decrease in moisture content affected performance of both products. Generally, rewettability is inversely proportional to wetting agent rate and moisture content, which accounts for the gradual decline in effectiveness of the two wetting agents with time. ACA0160 did, however, demonstrate superior rewetting characteristics even after severe dehydration of the peat.
Numerous modifications and variations of the pre~ent invention are included in the above-identified specification and are expected to be obvious to one of skill in the art. For example, the use of the compounds 2 o ~

of this invention for their advantageous properties as wetting agents or surfactants in other than soilless media may be expected. Additionally, these compounds may prove useful for asbestos removal. Thus, other uses for these compounds may become obvious upon a review of their advantageous properties. Modifications and alterations to the compositions and processes of the present invention to suit such other uses are believed to be encompassed in the scope of the claims appended hereto.

Claims (26)

1. A compound useful as a plant growth media wetting agent characterized by the formula wherein n is an integer of between 5 to 16, R1 is the same as R2 or a lower alkyl containing from 5 to 7 carbon atoms, and R2 is a lower alkyl containing from 5 to 7 carbon atoms.

2. The compound according to claim 1 wherein n is an integer of between 7 to 11.

3. The compound according to claim 2 wherein n is 9.

4. The compound according to claim 1 wherein R1 is the same as R2 and is a C5 amyl alkyl group.

5. The compound according to claim 4 wherein n is 9.

6. The compound according to claim 4 wherein n is 6.

7. The compound according to claim 4 wherein n is 12.

8. A wetting agent for application to plant growth media comprising at least one compound according to claim 1 in admixture with a suitable carrier.

9. The wetting agent according to claim 8 wherein said suitable carrier is water.

10. The wetting agent according to claim 8 wherein said suitable carrier is a dry carrier.

11. The wetting agent according to claim 10 wherein said carrier is vermiculite.

12. The wetting agent according to claim 9 wherein said compound is present in water in a concentration of between 10 and 3000 ppm.

13. The wetting agent according to claim 10 wherein said compound is present with a dry carrier in a concentration of between 15 and 40%.

14. A wetting agent for application to plant growth media comprising a mixture of compounds according to claim 1 in admixture with a suitable carrier.

15. The agent according to claim 14 comprising a mixture of compounds of claim 1, each said compound characterized in that n is between 5 and 16.

16. The agent according to claim 15 comprising a mixture of compounds of claim 1, each said compound characterized in that n is between 7 and 11.

17. The agent according to claim 16 comprising a mixture of compounds of claim 1, wherein the average of n is 9.

18. The agent according to claim 8 wherein said compound is

19. The agent according to claim 14 wherein one of said compounds is

20. The agent according to claim 14 wherein said carrier is water.

21. The agent according to claim 14 wherein said carrier is a dry carrier.

22. The agent according to claim 21 wherein said carrier is vermiculite.

23. The agent according to claim 20 wherein said compound is present in water in a concentration of between 10 to 3000ppm.

24. The agent according to claim 21 wherein said compound is present in the dry carrier in a concentration of between 15 to 40%.

25. A process for improving the moisture penetration, absorption and retention of plant growth media comprising applying to said media a wetting agent of claim 8 in an effective concentration.

26. The process according to claim 25 wherein said concentration is between 1 to 5 ounces per cubic yard.