WO2020094925A1

WO2020094925A1 - A high efficiency defoamer composition

Info

Publication number: WO2020094925A1
Application number: PCT/FI2019/050792
Authority: WO
Inventors: Yong Zou; Luciana Bava
Original assignee: Kemira Oyj
Priority date: 2018-11-08
Filing date: 2019-11-07
Publication date: 2020-05-14

Abstract

The present invention relates to an environmentally friendly hydrophobic defoamer composition, comprising a deep eutectic solvent comprising a quaternary ammonium salt as a hydrogen bond acceptor (HBA) and an alkoxylated fatty alcohol as a hydrogen bond donor (HBD). The invention relates also to a use of the defoamer composition and to a method of making it.

Description

A HIGH EFFICIENCY DEFOAMER COMPOSITION

This invention relates to a defoamer composition, its use as well as a method for preparing a defoamer composition. The defoamer composition is especially suitable for pulp and paper industry, as well as in any other processing industry where foaming is a significant issue, problem or a hurdle.

Defoamers are widely used in many industries including but not limited to pulp, paper, petroleum, textile and mining industries, water treatment, paints and coatings, food and beverage processing, and agriculture.

Defoamers are generally composed of a defoaming agent, such as, but not limited to ethylene bis(stearamides) (EBS) and/or hydrophobic silica, a carrier fluid, and other miscellaneous additives.

Defoamers have primarily two functions, these functions being defoaming and anti- foaming. Knockdown and longevity of defoamers provide important information about the performance of defoamers. Upon formation of foam in a solution the density of the solution decreases. Addition of a defoamer breaks the foam and the density of the solution increases again. The rate of the increase of the density due to the addition of a defoamer indicates how fast the defoamer acts, which is called the knockdown phase. The quicker the knockdown, the more efficient the defoamer is. However, the defoaming effect is temporary and with time the defoamer begins to lose its efficacy and the density starts dropping again as the foam starts to regenerate. The longevity of or persistence of a defoamer indicates how long the defoamer works. The longer the longevity or persistence of a defoamer, the more efficient the defoamer is. An ideal defoamer would have fast knockdown and long longevity or will persist over long time i.e. foam would disappear quickly upon addition of the defoamer and it would take longer time for the foam to regenerate.

Although commercially available defoamers generally have relatively fast knockdown, they have poor longevity or persistence. Currently available defoamers quickly lose their efficacy and density starts dropping rapidly, which is seen as reappearance of the foam. As it currently stands, in the pulp and paper industry specifically, silicone based defoamers are preferred over other defoamers due to lower dosage requirement and cost-effective performance.

However, having said that, silicone based defoamers present themselves with inherent challenges and issues. These challenges are, in part, characterized by environmental and regulatory, carry over/deposit and cost efficiency issues and are further related to complex manufacturing processes. However, in order to increase the longevity of silicone based defoamers one would need to use larger amounts of these defoamers in the process. This would in turn result in additional inherent problems due to presence of higher amounts of hydrophobic components, such as silicone compounds in the process. Hydrophobic components exhibit a tendency to stick on the fiber, and excess amounts of hydrophobic components would necessitate additional washing steps later in the process. Therefore, the amounts of hydrophobic components in the end fiber need to be limited and an excess amount of silicone based defoamers cannot be a reliable solution to limited longevity of the defoamers.

Various industries have long sought for a substitution for silicone based defoamers, in part, as a potential goal to overcome the challenges experienced thus far with silicone based defoamers. Various ester based defoamers have been developed for alternatives to silicone based defoamers. However, there is still a need for further defoamers.

Therefore, clearly there is a need to develop novel and efficient defoamers that are first and foremost environmentally friendly, cost effective, simple to make and stable but at the same time would display longer longevity along with a fast knockdown phase.

EP 0404317 discloses a use of ethoxylated propoxylated alcohols to prevent or reduce foam in fermentation broths. US 6,462,014 discloses hydrotropic alkoxylated quaternary ammonium with non- ionic surfactant based on branched alcohols.

Florindo et al., ACS Sustainable Chem. Eng. (2018), Vol. 6(3), pp. 3888 - 3894, have prepared hydrophobic, low viscous deep eutectic solvents based on fatty acids in order to extract bisphenol A from water.

Cao et al., ACS Sustainable Chem. Eng. (2017) Vol. 5(4), pp. 3270 - 3278, have disclosed hydrophobic deep eutectic solvents for extracting Artemisinin from Artemisia annua leaves.

Florindo et al., Fluid Phase Equilibria (2017) Vol. 448, pp. 135 - 142, have disclosed the use of hydrophobic deep eutectic solvents for the extraction of pesticides from aqueous environments. van Osch et al., Green Chemistry (2015), Vol. 17, pp. 4518 - 4521 , have disclosed preparing hydrophobic deep eutectic solvents by using decanoic acid and various quaternary ammonium salts for recovering volatile fatty acids from aqueous solutions.

Finally, Ribeiro et al.,ACS Sustainable Chem. Eng. (2015), Vol. 3(10), pp. 2469 - 2477, have used hydrophobic eutectic mixtures based on DL-menthol and naturally occurring acids, e.g. pyruvic acid, L-lactic acid, and lauric acid for extracting caffeine, tryptophan, isophthalic acid and vanillin compounds.

Summary of the Invention

One objective of the present invention is to provide solutions to the problems encountered in the prior art.

Another objective of the present invention is to provide an effective and environmentally friendly defoamer, which displays long longevity and fast knockdown phase. These objects are attained with the invention having the characteristics presented below in the characterizing parts of the independent claims. Some preferable embodiments are disclosed in the dependent claims.

The embodiments mentioned in this text relate, where applicable, to all aspects of the invention, namely the defoamer composition, its use as well as to the method of preparing it, even if this is not always separately mentioned.

A typical environmentally friendly hydrophobic defoamer composition according to the present invention comprises a deep eutectic solvent comprising a quaternary ammonium salt as a hydrogen bond acceptor (HBA) and an alkoxylated fatty alcohol as a hydrogen bond donor (HBD).

A typical method according to the present invention for preparing an environmentally friendly hydrophobic defoamer composition according to the invention comprises reacting a quaternary ammonium salt as a hydrogen bond acceptor (HBA) with an alkoxylated fatty alcohol as a hydrogen bond donor (HBD) at an elevated temperature, preferably under continuous stirring.

Typical use according to the present invention of a defoamer composition according to the invention is for decreasing foam formation in manufacture of pulp, paper, board, tissue or the like. Insofar, as is apparent to Applicant’s knowledge, this is the first time that hydrophobic deep eutectic solvents are used for defoaming purposes, especially in manufacture of pulp, paper, board, tissue or the like.

Surprisingly, the current embodiments of the instant invention now propose and set forth a hydrophobic deep eutectic solvent defoamer using a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD) with better defoaming properties as compared to ester based defoamers.

Other objects, features and advantages of the present invention will become apparent from the following detailed description. It should be understood, however, that the detailed description and the specific examples, while indicating specific embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief Description of the Drawings

The following drawings form part of the present specification and are included to further demonstrate certain aspects of the present invention. The invention may be better understood by reference to one or more of these drawings in combination with the detailed description of the specification embodiments presented herein.

FIG. 1A shows a Foam and Entrained Air Test (FEAT) graph, density versus time profile at 60°C for the compositions D-FI3-1 -2hrs, D-FI3-2, DES-FI2, D-FI3-1 -4hrs and the commercial defoamer reference FT 2543 in accordance with some embodiments of the current invention and FIG. 1 B shows the performance of the compositions D-FI3-1-2hrs, D-FI3-2, D-FI3-1 -4hrs, Des-FI2, and FT 2543 as measured by Area Under Curve (AUC) at 30 seconds and 3 minutes.

FIG. 2A shows a Foam and Entrained Air Test (FEAT) graph, density versus time profile at 60°C for the compositions AD-6, AD-7, AD-8 and the commercial defoamer reference FT 2543 in accordance with some embodiments of the current invention and FIG. 2B shows the performance of the compositions AD-6, AD-7, AD-8, and FT 2543 as measured by Area Under Curve (AUC) at 30 seconds and 3 minutes.

Detailed Description of the Invention

Foaming is a common problem in many industrial processes, especially in pulp washing processes and papermaking operations, where foam can prevent the proper formation of the finished paper and disrupt manufacturing operations. Commercially available defoamers, although generally having fast knockdown, however, have limited longevity or persistence. Once the defoamer loses its efficacy, the density of the medium decreases and foam starts to regenerate. Adding more defoamer is not a solution to increase the defoaming effect because excess amounts of hydrophobic particles would lead to carryover on the final fiber and require additional washing steps. It is surprisingly found for the first time in accordance with the various embodiments of the current invention a defoamer composition comprising hydrophobic deep eutectic solvent composed of a quaternary ammonium salt, preferably an alkyl dimethyl benzyl ammonium chloride, used as a hydrogen bond acceptor (HBA) and an alkoxylated fatty alcohol, used as a hydrogen bond donor (HBD). The defoamer composition according to the invention performs well as a defoamer and shows improved performance when compared to commonly used ester based defoamers. It is surprisingly found that the chemical defoaming efficacy of the defoamer composition is superior compared to conventionally used ester based defoamers. Further, the novel hydrophobic defoamer compositions comprising deep eutectic solvents present themselves by being devoid of the significant undeniable challenges equally faced with silicone based defoamers. Advantageously, in certain embodiments, a better defoaming performance of the composition compared to an ester based defoamer reference is verified at a temperature of 60° C, by determining the density of a mixture medium as a function of time, the mixture medium including a foaming medium, for example paper mill white water.

According to some advantageous embodiments, an improved defoaming performance of the composition compared to a silicone based defoamer reference is tested at a temperature of 60° C, by determining the density of a mixture medium as a function of time, the mixture medium including a foaming medium, for example paper mill white water.

The hydrogen bond acceptor (HBA) may be selected from various quaternary ammonium salts acting as the hydrogen bond acceptor. According to one embodiment the quaternary ammonium salt may be selected from alkyl dialkyl benzyl ammonium halide salts, tetraalkyl ammonium halide salts and alkoxylated quaternary ammonium compounds. The quaternary ammonium salt may be an C8-C18 alkyl dialkyl benzyl ammonium halide salt, more preferably C12-C18 alkyl dialkyl benzyl ammonium halide salt. According to one preferable embodiment the quaternary ammonium salt may be an alkyl dimethyl benzyl ammonium halide salt, preferably C8-C18 alkyl dimethyl benzyl ammonium halide salt, more preferably C12-C18 alkyl dimethyl benzyl ammonium halide salt.

According to one embodiment the quaternary ammonium salt may be a tetraalkyl ammonium halide salt, where at least three of the alkyl groups have a chain length of 4 - 8 carbon atoms. The halide salt may be, for example, chlorine, bromide, fluoride or iodine. In some advantageous embodiments, the quaternary ammonium salt (HBA) may be selected from the group consisting of, but not limited to, tetrabutylammoniumchloride, tetraheptylammonium chloride, tetraoctylammonium chloride, tetraoctylammonium bromide, methyltrioctylammonium chloride, alkyl dimethyl benzyl ammonium chloride, and methyltrioctylammonium bromide.

According to one preferable embodiment the quaternary ammonium salt is selected from alkoxylated quaternary ammonium compounds, such as monoethoxylated ammonium compounds, ethoxylated ammonium compounds or bis(ethoxylated) ammonium compounds, for example ethyl bis(polyethoxyethanol) tallow ammonium ethosulfate. According to an advantageous embodiment, the quaternary ammonium salt may be ethyl bis(polyethoxyethanol) tallow ammonium ethosulfate.

The hydrogen bond donor (HBD) may be chosen from various alkoxylated fatty alcohols capable of acting as a hydrogen bond donor. According to one preferable embodiment the alkoxylated fatty alcohol may be selected from alkoxylated C10- C18 fatty alcohols or mixtures of alkoxylated C10-C18 fatty alcohols. In one embodiment the alkoxylated fatty alcohol is a mixture of alkoxylated C16-C18 fatty alcohols or the alkoxylated fatty alcohol is a mixture of alkoxylated C12-C14 fatty alcohols. According to some advantageous embodiments the defoamer composition may have an HBD/HBA ratio (weight ratio) ranging from 3:1 to 20:1 , preferably from 5:1 to 9:1 .

In some advantageous embodiments, the defoamer composition comprises C12- C18 alkyl dimethyl benzyl ammonium chloride as hydrogen bond acceptor and a mixture of alkoxylated C16-C18 fatty alcohols as hydrogen bond donor. A mixture of these components, the HBD/HBA weight ratio being 9.0:1 , is heated under reaction conditions of an elevated temperature for 2 hours or 4 hours.

In still other advantageous embodiments, the defoamer composition comprises C12-C18 alkyl dimethyl benzyl ammonium chloride as hydrogen bond acceptor and a mixture of alkoxylated C16-C18 fatty alcohols as hydrogen bond donor. The HBD/HBA weight ratio may be 18.0:1 or 5.0:1 , and the mixture is heated at an elevated temperature for 2 hours.

In still other advantageous embodiments, the defoamer composition comprises C12-C18 alkyl dimethyl benzyl ammonium chloride as hydrogen bond acceptor and a mixture of alkoxylated C12-C14 fatty alcohols as hydrogen bond donor. The HBD/HBA weight ratio may be from 3.0:1 to 10.0, for example 10.0:1 or 5.0:1 or 3.0:1 , and the mixture is heated at 80 °C for 2 hours.

The defoamer composition preferably comprises less than 10 weight-%, more preferably less than 5 weight-%, even more preferably less than 2.5 weight-%, sometimes even less than 1 weight-%, of water. According to one preferable embodiment the defoamer composition is substantially water-free.

To prepare the defoamer, in accordance with some embodiments of the invention, an HBA may be added to an HBD in order to form a mixture either continuously and/or at certain intervals in order to form a eutectic mixture. The reverse equally holds true, in which case, the HBD may be added to the HBA either continuously and/or at certain intervals. The amount of HBA/HBD added, the time interval, and the time duration of addition depend on factors including but not limited to the components being used.

The HBA can be added in multiple batches to the HBD. In some embodiments the HBA is added before the HBD. In certain embodiments the HBA is added after the HBD. In other embodiments the HBA and the HBD are added at the same time simultaneously and separately. In yet other embodiments the HBA is added both before and after the HBD. In yet other embodiments the HBA is added before and at the same time as of the HBD. In some embodiments the HBA is added at the same time and after the HBD. According to some embodiments the HBA is added before, after and at the same time as of the HBD.

According to some embodiments of the invention, the defoamer composition is prepared by reacting the hydrogen bond acceptor (HBA) with the hydrogen bond donor (HBD) at elevated temperature, which may be in a range of 50 - 90 °C, preferably 70 - 90 °C, more preferably 80 - 90 °C.

According to some embodiments of the invention, the reaction temperature of the of HBA and HBD added separately but simultaneously to form a mixture is at least 80°C.

The reaction between the hydrogen bond donor and the hydrogen bond acceptor may be conducted at the elevated temperature, preferably by mixing under continuous stirring, with a reaction time of at least 30 minutes, preferably of at least 1 .5 hours. According to some embodiments of the invention, the reaction is conducted with a reaction time of HBA and HBD of at least 2 hours. According to still other embodiments, the reaction is carried out with a reaction time of HBA and HBD of at least 2.5 hours. According to yet other embodiments, the reaction is carried out with a reaction time of HBA and HBD of at least 3.0 hours. According to further other embodiments, the reaction is carried out with a reaction time of HBA and HBD of at least 3.5 hours. According to still other embodiments, the reaction is carried out with a reaction time of HBA and HBD of at least 4.0 hours. According one embodiment the reaction time may be 30 - 300 min, preferably 60 - 240 min, more preferably 120 - 240 min.

According to one preferable embodiment of the present invention the environmentally friendly hydrophobic defoamer composition may be prepared by a method including mixing a C12-C18 alkyl dimethyl benzyl ammonium chloride, used as a hydrogen bond acceptor (HBA), with a C16-C18 alkoxylated fatty alcohol, used as a hydrogen bond donor (HBD), under continuous stirring. The mixing may be conducted at a temperature ranging from 80°C - 90°C for 100 - 120 minutes.

According to another preferable embodiment of the present invention the environmentally friendly hydrophobic defoamer composition may be prepared by a method including mixing a C12-C18 alkyl dimethyl benzyl ammonium chloride, used as a hydrogen bond acceptor (HBA), with a C12-C14 alkoxylated alcohol, used as a hydrogen bond donor (HBD), under continuous stirring. The mixing may be conducted at a temperature ranging from 50 °C - 90 °C for 30 - 180 minutes, preferably at a temperature ranging from 70 °C - 80 °C for 60 - 120 minutes.

According to advantageous embodiments, the main target to treat and thereby defoam, is an industrial process liquid medium including various liquids, slurries and suspensions, preferably a liquid, slurry or suspension derived from the pulp and paper industry.

According to one aspect of the present invention the method for controlling foam in papermaking process comprises the steps of adding to a pulp slurry and/or suspension a defoamer composition disclosed herein. The defoamer can be added to the liquid, slurry or suspension continuously and/or at certain intervals. Amounts of the defoamer added, time interval, and time duration of addition depend on, factors including but not limited to, amount of the liquid, slurry or suspension to be treated, properties and components of the liquid, slurry or suspension, amount of foam, foaming susceptibility of the liquid, slurry or suspension and on the process itself. According to one embodiment of the invention the defoamer composition may be added to a liquid medium in amount of 10 - 50 ppm, preferably 15 - 45 ppm, more preferably 20 - 30 ppm, especially in processes related to manufacture of pulp or paper.

The composition and methods of the present invention can in reality be practiced in any industrial process, in which foaming is a concern, including but not limited to process streams commonly encountered when processing or manufacturing wood pulp, paper, textiles, cement or paint, in addition to processes for treating industrial wastewater, food processing, and oil drilling. The composition and methods can be used practically with any industrial water system or liquid medium where foaming is a problem, but are particularly well-adapted to recirculating water systems as found in the following but not limited to papermaking systems, cooling water systems (including cooling towers, open and closed loop cooling units), industrial raw water systems, drinking water distribution systems, sanitizing drinking water system, oil production or recovery systems (oil field water system, drilling fluids), fuel storage system, metal working systems, heat exchangers, reactors, equipment used for storing and handling liquids, boilers and related steam generating units, radiators, flash evaporating units, refrigeration units, reverse osmosis equipment, gas scrubbing units, blast furnaces, sugar evaporating units, steam power plants, geothermal units, nuclear cooling units, water treatment units, pool recirculating units, mining circuits, closed loop heating units, machining fluids used in operations such as for example drilling, boring, milling, reaming, drawing, broaching, turning, cutting, sewing, grinding, thread cutting, shaping, spinning and rolling, hydraulic fluids, cooling fluids, and the like. In some embodiments, the industrial process stream is an industrial process stream in a cement-making process or a paint- making process.

Definitions

As used herein, the term“solvent”, refers to a substance that dissolves a solute, e.g. chemically distinct liquid, solid or gas, thereby resulting in a solution. A solvent is usually a liquid but can equally also be a solid, a gas, or a supercritical fluid. The quantity of solute that can dissolve in a specific volume of solvent varies with temperature.

As used herein, the term“deep eutectic solvent” denotes a liquid, which is a mixture of two or more individual components, which has a melting point below the melting points of the individual pure components. A deep eutectic solvent is usually prepared by mixing the individual components under elevated temperature, which leads to self-association of the components probably through hydrogen bond interactions. Usually deep eutectic solvents have melting point <100 °C, and preferably they are in liquid form at temperature 20 - 40 °C.

All ratios herein in this disclosure are meant to reflect weight-ratios, unless explicitly stated otherwise.

For the purpose of the current application, defoamers are chemicals that break foam after it has been formed and/or prevent foam formation, also otherwise known as anti-foam agents and/or remove air bubbles from a liquid and helps them to rise to the surface, also otherwise known as air release agents.

Defoaming composition of the present invention prevents, controls and/or reduces foaming. Prevention of foaming means not letting the foam being formed, control of foaming means limiting amount of foam to certain extent or amount depending on the process, reduction of foaming means a decrease in the amount of foam. Defoaming composition of components of the current invention are to be used to treat aqueous liquids susceptible to foaming and/or foam containing aqueous liquids. Treating the liquids with the defoamers is achieved by adding the defoamer to the liquids or vice versa.

Components of the defoaming compositions of the current invention shows synergistic behavior, thus the defoaming efficiency of the composition is much higher than that of the individual components. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. All technical and scientific terms used herein have the same meaning. Although any materials similar or equivalent to those described herein can also be used in the practice of the present invention, exemplary materials are described for illustrative purposes.

As used herein and in the appended claims, the singular form “a,”“and,”“the” include plural referents unless the context clearly dictates otherwise. All technical and scientific terms used herein have the same meaning.

It should be understood that operations, and in particular, the method steps may be shown and described as being in a sequence or temporal order, but they are not necessarily limited to being carried out exactly as claimed and can therefore be carried out in any particular sequence or order.

The terms “comprises,” “comprising,” “includes,” “including,” “having” and their conjugates mean“including but not limited to.” Terms and phrases used in this application, and variations thereof, unless otherwise expressly stated, should be construed as open ended as opposed to limiting. As examples of the foregoing, the term“including” should be read as meaning“including, without limitation” or the like. The term“example” is used to provide exemplary instances of the item in discussion, not an exhaustive or limiting list thereof. Adjectives such as e.g.,“conventional,” “traditional,”“known” and terms of similar meaning should not be construed as limiting the item described to a given time period, or to an item available as of a given time. But instead these terms should be read to encompass conventional, traditional, normal, or standard technologies that may be available, known now, or at any time in the future.

Likewise, a group of items linked with the conjunction“and” should not be read as requiring that each and every one of those items be present in the grouping, but rather should be read as“and/or” unless expressly stated otherwise. Similarly, a group of items linked with the conjunction“or” should not be read as requiring mutual exclusivity among that group, but rather should also be read as“and/or” unless expressly stated otherwise. The presence of broadening words and phrases such as“one or more,”“at least,”“but not limited to,” or other like phrases in some instances shall not be read to mean that the narrower case is intended or required in instances, wherein such broadening phrases may be absent.

It will be readily understood by one of ordinary skill in the relevant art that the present invention has broad utility and application. Although the present invention has been described and illustrated herein with referred to certain embodiments, it will be apparent to those of ordinary skill in the art that other embodiments may perform similar functions and/or achieve like results, and that the described embodiments are for illustrative purposes only. Thus, it should be understood that various features and aspects of the disclosed of the disclosed embodiments can be combined with or substituted for one another in order to form varying modes of the disclosed invention. Many different embodiments such as variations, adaptations, modifications, and equivalent arrangements are will be implicitly and explicitly disclosed by the embodiments described herein, and thus fall within the scope and spirit of the present invention.

Further, the discussed prior art is not an admission by Applicant and should not be construed that the current invention does not antecede and is not patentable over the discussed prior art, but has merely been presented to better define the knowledge in the field to a skilled artisan and to the reader in general.

Thus, the scope of the embodiments of the present invention should be determined by the appended claims and their legal equivalents. Examples and figures are exemplary.

Examples

The following examples as well as the Figures are included to demonstrate the various embodiments of the invention. It should be appreciated by those of skill in the art that the techniques disclosed in the Examples and Figures represent techniques discovered by the inventors to function well in the practice of the invention, and thus can be considered to constitute preferred modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or similar result without departing from the spirit and scope of the invention.

Foam and Entrained Air Tests (FEAT) were performed to test the defoaming efficiency of compositions in accordance with embodiments of the present invention. FEAT test employs a testing apparatus, which used to determine the efficacy of defoamer compositions in a laboratory setting. The apparatus measures the change in the density as a function of time of the filtrate as the defoamer composition is introduced. The measure of the change in density of a filtrate is a direct measurement of the change in entrained air. In pulp and paper mills, for example, presence of entrained air can disturb sheet formation and drainage.

The experimental set up contains a water bath, temperature control, a foam column, a micropump, a density meter, a computer, and acquisition software. Testing of the samples utilizes a recirculatory foam column attached to a pump. The hose leading from the pump is connected to a density meter, which is connected back to the top of the foam column. The foaming medium is added to the test unit and pumped through the unit to fill the lines. Once the pump is turned on and the density drops due to air entrainment, a defoamer composition is added. The test is run for a predetermined time and adequate number of data points are collected by the data acquisition software. A line graph is generated to show the change in density of the liquor of the time period. The area under the curve for each test is then calculated. Those samples having the highest area under the curve measurements are those samples that performed the best.

For each of the Examples, white water was used as the foaming medium. 400 ml_ of the foaming medium was heated to 60° C and circulated. As the medium was circulated, the density of the medium dropped due to formation of foams. The defoaming property was tested at 60° C. Following abbreviations for tested defoamer compositions have been used in the Examples:

D-H3-1-2hrs C12-C18 alkyl dimethyl benzyl ammonium sulphate (HBA), C16-C18 alkoxylated alcohol (HBD); HBD:HBA weight ratio 9:1 , heated at 80 °C for 2 hours; D-H3-1-4hrs\ C12-C18 alkyl dimethyl benzyl ammonium sulphate (HBA), C16-C18 alkoxylated alcohol (HBD); HBD:HBA weight ratio 9:1 , heated at 80 °C for 4 hours; D-H3-2\ C12-C18 alkyl dimethyl benzyl ammonium sulphate (HBA), C16-C18 alkoxylated alcohol (HBD); HBD:HBA weight ratio 18:1 , heated at 80 °C for 2 hours; Des-H2\ C12-C18 alkyl dimethyl benzyl ammonium sulphate (HBA), C16-C18 alkoxylated alcohol (HBD); HBD:HBA weight ratio 5:1 , heated at 80 °C for 2 hours; AD-8\ C12-C18 alkyl dimethyl benzyl ammonium sulphate (HBA), C12-C14 alkoxylated alcohol (HBD); HBD:HBA weight ratio 10:1 , heated at 80 °C for 2 hours; AD-7\ C12-C18 alkyl dimethyl benzyl ammonium sulphate (HBA), C12-C14 alkoxylated alcohol (HBD); HBD:HBA weight ratio 5:1 , heated at 80 °C for 2 hours; AD-6\ C12-C18 alkyl dimethyl benzyl ammonium sulphate (HBA), C12-C14 alkoxylated alcohol (HBD); HBD:HBA weight ratio 3:1 , heated at 80 °C for 2 hours.

Example 1 Efficacy of D-H3-1 -2hrs, D-H3-2, D-H3-1 -4hrs, and Des-H2 defoamer compositions increased compared to the commercial defoamer standard reference product FT 2543

10 pl_ D-H3-1 -2hrs, D-H3-2, D-H3-1 -4hrs, and Des-H2 defoamer was added to the medium when the medium density reached a desired minimum point. As seen in FIG. 1 A the density, i.e. knockdown phase, increased rapidly to a maximum density of approximately 0.970 g/cm³ for D-H3-1 -2hrs, D-H3-1 -4hrs and Des-H2 and to a maximum density of approximately 0.958 g/cm³ both for D-H3-2 and for FT 2543. Thereafter, as can be seen in FIG. 1A, the density then only dropped to approximately 0.945 g/cm³ for D-H3-2 but not for D-H3-1-2hrs, D-H3-1 -4hrs and Des-H2. In other words, these compositions not only displayed an increased efficacy in defoaming the medium compared to the commercial defoamer standard reference product FT 2543, but they also sustained the longevity of defoaming the medium, as a drop in the density was not observed in the tested time-frame of the medium. The performance as measured by Area Under Curve (AUC) confirmed these findings, where D-H3-1 -2hrs, D-H3-1 -4hrs and Des-H2 exhibited an increased defoaming property compared to FT 2543, as the bars were higher except for D-H3- 2 as displayed in FIG. 1 B after 30 seconds and 3 minutes.

Example 2 Efficacy of AD-6 and AD-7 defoamer compositions increased compared to the commercial defoamer standard reference product FT 2543

10 pl_ AD-6, AD-7 and AD-8 defoamer was added to the medium when the medium density reached a desired minimum point. As seen in FIG. 2A the density, i.e. knockdown phase, increased rapidly to a maximum density of approximately 0.970 g/cm³ for AD-6 and AD-7 and to a maximum density of approximately 0.948 g/cm³ for AD-8 and approximately 0.958 g/cm³ for FT 2543. Thereafter, as can be seen in FIG. 2A, the density did not drop for any of the compositions, thereby sustaining the longevity of the defoaming property. AD-6 and AD-7 were better at defoaming the medium compared to the commercial defoamer standard reference product FT 2543, as the graphs were consistently higher than for FT 2543. The performance as measured by Area Under Curve (AUC) confirmed these findings, where AD-6 and AD-7 exhibited an increased defoaming property compared to FT 2543, as the bars were higher except for AD-8 as displayed in FIG. 2B after 30 seconds and 3 minutes.

Claims

1. An environmentally friendly hydrophobic defoamer composition, comprising a deep eutectic solvent comprising a quaternary ammonium salt as a hydrogen bond acceptor (HBA) and an alkoxylated fatty alcohol as a hydrogen bond donor (HBD).

2. The composition of claim 1 , wherein the quaternary ammonium salt is selected from alkyl dialkyl benzyl ammonium halide salts, tetraalkyl ammonium halide salts and alkoxylated quaternary ammonium compounds.

3. The composition of claim 1 or 2, wherein the quaternary ammonium salt is alkyl dimethyl benzyl ammonium halide salt, preferably C8-C18 alkyl dimethyl benzyl ammonium halide salt, more preferably C12-C18 alkyl dimethyl benzyl ammonium halide salt.

4. The composition of claim 1 or 2, wherein the quaternary ammonium salt is tetraalkyl ammonium halide salt, where at least three of the alkyl groups have a chain length of 4 - 8 carbon atoms.

5. The composition of claim 4, wherein the quaternary ammonium salt is selected from the group consisting of tetrabutylammoniumchloride, tetraheptylammonium chloride, tetraoctylammonium chloride, tetraoctylammonium bromide, methyltrioctylammonium chloride and methyltrioctylammonium bromide.

6. The composition of claim 2, wherein the alkoxylated quaternary ammonium compound is ethyl bis(polyethoxyethanol) tallow ammonium ethosulfate.

7. The composition of any of the preceding claims 1 - 6, wherein the alkoxylated fatty alcohol is selected from alkoxylated C10-C18 fatty alcohols or mixtures of alkoxylated C10-C18 fatty alcohols.

8. The composition of claim 7, wherein the alkoxylated fatty alcohol is a mixture of alkoxylated C16-C18 fatty alcohols or a mixture of alkoxylated C12-C14 fatty alcohols.

9. The composition of any of the preceding claims 1 - 8, wherein the composition has an HBD/HBA weight ratio ranging from 3:1 to 20:1 , preferably from 5:1 to 9:1 .

10. The composition according to any of claims 1 - 9, wherein the composition comprises less than 10 weight-%, preferably less than 5 weight-%, more preferably less than 2.5 weight-%, of water.

1 1 . Use of a defoamer composition according to any of claims 1 - 10 for decreasing foam formation in manufacture of pulp, paper, board, tissue or the like.

12. Use according to claim 1 1 , wherein the defoamer composition is added to a liquid medium in amount of 10 - 50 ppm, preferably 20 - 30 ppm.

13. A method of preparing an environmentally friendly hydrophobic defoamer composition according to any of claims 1 - 10, said method comprising reacting quaternary ammonium salt as a hydrogen bond acceptor (HBA) with an alkoxylated fatty alcohol as a hydrogen bond donor (HBD) at an elevated temperature, preferably under continuous stirring.

14. The method of claim 13, wherein the elevated temperature is in a range of 50 - 90 °C, preferably 70 - 90 °C.

15. The method of claim 13 or 14, wherein the reacting of the hydrogen bond acceptor (HBA) with the hydrogen bond donor (HBD) at elevated temperature is conducted with a reaction time of at least 30 minutes, preferably of at least 1 .5 hours.