Olefinic succinic anhydride emulsifiers

Abstract

An emulsifier for forming a stable molten wax or oil in water emulsion comprises a dispersion of olefinic succinic anhydride in a continuous aqueous phase.

Description

OLEFINIC SUCCINIC ANHYDRIDE EMULSIFIERSCROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present application claims priority to US Application No. 63 / 639,515, filed April 26, 2024, the entire contents of which are incorporated herein by reference.FIELD

[0002] The present description relates to emulsifiers for use in producing wax and / or oil-in-water emulsions. More particularly, the description relates to emulsifiers comprising a dispersion of olefinic succinic anhydride in an aqueous medium.BACKGROUND

[0003] Composite wood panels, such as particleboard, medium density fibreboard (MDF), oriented strand board (OSB), and other similar products, are generally manufactured by combining wood flakes, chips, particles, and / or fibers with a resin followed by curing of the resin in a continuous or multi-opening hot press. It is known in the art to include a wax component into the panel manufacturing process, wherein the hydrophobic wax component imparts water repellency characteristics to the wood-based panels, or boards. As such, moisture is impeded from being absorbed into such panels, thereby preventing deterioration. Additionally, the presence of the wax improves the manufacturing process of composite wood panels.

[0004] Waxes used in composite panel production are typically paraffin waxes which, depending on the oil content and wax hardness, can be further classified as slack wax, scale wax, or refined wax. Traditionally, these waxes are applied onto the wood flakes, chips, particles or fibers as a molten wax (“slack application”) or dispersed as small solid wax particles suspended in water (“dispersion application”). It is believed that, when compared to slack application, wax dispersions result in improved wax distribution during application and therefore improved water repellency performance of the formed panel.

[0005] A method for the use of a wax composition for improving water repelling characteristics of composite wood panels is disclosed in US 6,908,677. The wax composition in this reference comprises an emulsion of liquid particles in a fluid where the particles are suspended by buoyancy, wherein the composition is created by forming adispersed phase of molten wax droplets in hot water. This reference does not disclose the use of an emulsifier, dispersant or stabilizer in forming the wax composition.

[0006] Yet another application of wax in the production of wood composite panels involves the use of hydrodynamic cavitation. US 9,920,204 discloses a method for making a composite product by applying resin and an emulsified hydrophobizing composition consisting of one or more waxes, water, and lignosulfonic acids or salts onto a plurality of lignocellulosic substrates. The wax emulsion is manufactured using hydrodynamic cavitation and maintained at a temperature above 25°C for at least 20 minutes.

[0007] The emulsion application of wax for providing water repellent properties to wood composite panels is advantageous as the manufacture of these relatively unstable emulsions can be integrated into the manufacture of the wood composite panel. Emulsion application thus combines an environmental benefit as compared to dispersion application (i.e. elimination of the shipment of water) and a performance benefit as compared to slack application (i.e. improved wax distribution on the wood flakes, chips, particles, or fibers).

[0008] Coalescence describes a phenomenon in emulsions where two emulsion droplets collide and coalesce into a single emulsion droplet. All emulsions are susceptible to this phenomenon, and the rate of coalescence is an important driver of emulsion stability. The theory describes coalescence in terms of the product of the droplet collision rate and an energy barrier. If the energy barrier is low or non-existent, coalescence occurs upon collision. If the energy barrier is high, coalescence is unlikely to occur. In practical terms, the energy barrier is related to the packing of the emulsifier on the droplet interphase. US 6,908,677 describes the formation of an aqueous wax emulsion in the absence of an emulsifier. Although such an emulsion can be formed, there is no energy barrier preventing coalescence and the emulsion quickly coalesces resulting in the separation of the respective phases owing to the difference in densities of the two phases. This effect prohibits practical use of this known emulsion application strategy for wax. In practise, addition of an emulsifier is thus required to achieve sufficient stability to allow for manufacture, short-term storage, and application of the molten wax emulsion, as demonstrated by US 9,920,204.

[0009] Emulsifiers used in the commercial manufacture of wax emulsions are typically sodium or ammonium salts of lignosulfonic acids. These emulsifiers have been used in the manufacture of wax dispersions, see e.g. US 4,666,522. However, these require significantly higher amounts as compared to the more efficient emulsifiers based on fattyacids soaps, as is, for example, described in US 2,349,326. US Patent 9,920,204 teaches that 9 to 15 wt% based on the weight of the wax(es) of sodium or ammonium salts of lignosulfonic acids is required. For comparison, fatty acids soaps are typically used at 2 - 4 wt%. Use of large amounts of emulsifiers is detrimental to water repellency performance of the wax. Furthermore, wax emulsions produced with sodium or ammonium salts of lignosulfonic acids are known to be susceptible to biological decay. Emulsifiers for use in manufacturing wood-based products are also disclosed by Grauman-Neander (Grauman- Neander, Nels E., Wax-Based Emulsifiers for Wax Emulsions for Use in Engineered Wood Products, MSc. Thesis, McMaster University, 2012.)

[0010] There is therefore a need for emulsifiers for use in manufacturing wax emulsions that address at least one of the known deficiencies.SUMMARY

[0011] In one embodiment, the present description provides an emulsifier for forming a wax or oil in water emulsion, the emulsifier comprising a stable aqueous dispersion comprising a continuous aqueous phase, a base, and a dispersed phase comprising an olefinic succinic anhydride. In a preferred embodiment, the base is present in an amount sufficient to saponify the olefinic succinic anhydride in an aqueous phase.

[0012] In another embodiment, the description provides a stable wax or oil in water emulsion comprising a wax and an emulsifier as described herein. In one embodiment, the wax is a paraffin wax.

[0013] In another embodiment, the present description provides a method of preparing a stable wax or oil in water emulsion comprising mixing an emulsifier comprising olefinic succinic anhydride as described herein with a molten wax or with an oil. In one embodiment, the emulsifier is heated to a temperature above the melt temperature of the olefinic succinic anhydride.

[0014] In another embodiment there is provided a method of preparing a wood composite panel comprising: combining wood furnish with resin and adding an emulsion comprising a wax, water and an emulsifier comprising olefinic succinic anhydride as described herein and hot pressing the mixture to form wood composite panels.DETAILED DESCRIPTION

[0015] The following description is provided to exemplify one or more embodiments of the present subject matter. Although the embodiments illustrated herein may be described with reference to one or more specific features, it will be understood that, unless otherwise specified, all features described herein may be used interchangeably or in any combination with one or more other embodiments. Thus, any description of features relating one embodiment is not intended to limit the incorporation of such features to only that embodiment.

[0016] Certain terms are used herein and will be understood to have the following meanings.

[0017] “Composite wood panel”, or “panel”, as used herein, will be understood to mean any form of wood or cellulosic material-based panel. “Composite wood panel” will be understood to include particleboard, fibreboard, such as medium density fibreboard (MDF) and high density fibreboard (HDF), flakeboard, chipboard, oriented strand board (OSB), waferboard and other similar products, wherein wood or cellulosic material is mixed with adhesive and formed into a flat panel.

[0018] The terms “wood particles”, “wood substrate” or “wood furnish” will be understood to mean wood or lignocellulosic material commonly used in manufacturing composite wood panels. This term will, therefore, be understood to include wood particles, wood chips, wood shavings, wood wafers, wood strands, sawdust or other similar materials.

[0019] “Dispersion”, as used with respect to the present description, will be understood to mean a composition comprising a continuous liquid phase and a solid dispersed phase. See a / so “IUPAC. Compendium of Chemical Terminology”, 2nd ed. (the "Gold Book") compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).

[0020] “Emulsion”, as used with respect to the present description, will be understood to mean a composition comprising two immiscible liquids. For the present description, an emulsion will be understood to comprise a continuous aqueous phase and dispersed nonaqueous phase. See a / so “IUPAC. Compendium of Chemical Terminology”, 2nd ed. (the "Gold Book") compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). Such an emulsion is referred to herein as an oil-in-water (O / W) emulsion. As known in the art, the term “emulsion” may also be used in the reverse, namely,to identify a liquid aqueous phase dispersed within a continuous non-aqueous phase. Unless otherwise stated, the present description will generally be described in terms of the former meaning, i.e. an oil-in-water (O / W) emulsion.

[0021] “Suspension” as used with respect to the present description, will be understood to mean a dispersion comprising a continuous liquid phase and a dispersed phase of solid particles, the particles being suspended by buoyancy. See a / so “IUPAC. Compendium of Chemical Terminology”, 2nd ed. (the "Gold Book") compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997).

[0022] The term “emulsifier” as used herein will be understood to mean a surfaceactive agent (also called a “surfactant”) which lowers the surface tension of the medium in which it is dissolved, and / or lowers the interfacial tension with other phases. As known in the art, an emulsifier facilitates the formation of an emulsion and increases the colloidal stability of the resulting emulsion or dispersion (IUPAC, Compendium of Chemical Terminology, 2nd ed. (the "Gold Book") Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997)). For the present description, it will be understood that that the emulsifiers described herein are useful in the incorporation one or more waxes into the manufacturing process of wood-based panels.

[0023] The term “wax” as used herein will be understood to have its regular meaning in the art. In one aspect, the wax may comprise a wax component as known in the art that is used in the manufacture of wood-based panel to impart hydrophobic characteristics to such panels. In such case, the wax may typically comprise one or more paraffin waxes.Additionally, the term “wax” will also be used herein to refer to the alphaolefin succinic acid (OSA) component that is used to formulate the emulsifiers described herein.

[0024] “Solids” or “solids content” as used herein will be understood to refer to the amount (expressed as a weight percentage) of non-volatile material in a dispersion. As known in the art, these terms refer to the total amount of non-volatile material that remains after evaporation or drying to a constant weight.

[0025] “Acid value” or “AV” as used herein will be understood to mean a measure of the content of carboxylic acid functionality of the olefinic succinic anhydride wax. It is measured by titration with KOH and is expressed as the number of milligrams of KOHrequired to neutralize the carboxylic acids in 1 gram of olefinic succinic anhydride wax (mg KOH / g).

[0026] “Degree of functionalization” as used herein will be understood to mean the measure of the average number of succinic anhydride moieties per olefinic hydrocarbon and is expressed as moles of succinic anhydride per mole of olefinic hydrocarbon.

[0027] “Emulsifier to wax ratio” or “EWR” as used herein will be understood to mean weight-based percentage of the subject olefinic succinic anhydride as compared to the emulsified wax or waxes. The EWR is determined by dividing the amount of olefinic succinic anhydride by the amount of wax or waxes and expressed as a percentage. As would be known to persons skilled in the art, and particularly in the context of manufacturing woodbased panels and the like, a lower EWR is desirable as it results in a higher wax content by weight and thus improves the water resistance performance of the wax.

[0028] As used herein, the term “stable molten wax emulsion” is defined as a molten wax emulsion displaying minimal coalescence and / or creaming as determined visually from an emulsion stability test. The stability of the emulsion is assessed after 15 min at 80°C, using a qualitative classification scale (0 - 4) for the degree of creaming (“w”) and / or the degree of coalescence (“o”). A classification of “0”, i.e. no coalescence and / or creaming, and “1”, i.e. minimal coalescence and / or creaming after 15 min at 80°C, is considered a stable molten wax emulsion.

[0029] As used herein, the term “stable wax dispersion” is defined as an aqueous olefinic succinic anhydride wax dispersion displaying no visible creaming and / or wax fall-out (i.e., no appearance of a water layer), or a change in viscosity, for a period of at least two weeks at room temperature. In one embodiment the wax dispersions described herein are stable for several months.

[0030] The term “polyolefins” as used herein will be understood to have the meaning as normally used in the art. In particular, this term may be defined as a polymer produced through an addition reaction of olefins. Examples of polyolefins include polyethylene (PE), polypropylene (PP), and poly alphaolefins (PAO). For convenience PAO may be referred herein simply as “alphaolefin”. For the purposes of the present description, a polyolefin may comprise any known carbon chain length.

[0031] As used herein the term “grafting” is defined as a reaction in which one or more species of blocks (such as maleic anhydride subunits) are connected to a main chain of a macromolecule as side chains having constitutional or configurational features that differ from those in the main chain.

[0032] The term “base” as used herein will be understood as comprising any base known in the art for formulating emulsifiers as described herein. Examples of bases that can be used in the present description include potassium hydroxide (KOH), sodium hydroxide (NaOH), monoethanolamine (MEA) and triethanolamine (TEA). Other suitable bases will be known to persons skilled in the art.

[0033] The terms “comprise”, “comprises”, “comprised” or “comprising” may be used in the present description. As used herein (including the specification and / or the claims), and unless stated otherwise, these terms are to be interpreted as open-ended terms and as specifying the presence of the stated features, integers, steps or components, but not as precluding the presence of one or more other feature, integer, step, component or a group thereof as would be apparent to persons having ordinary skill in the relevant art. Thus, the term "comprising" as used in this specification means "consisting at least in part of’. When interpreting statements in this specification that include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as "comprise" and "comprised" are to be interpreted in the same manner.

[0034] The phrase “consisting essentially of’ or “consists essentially of’ will be understood as generally closed terms, with the exception of allowing inclusion of additional items, materials, components, steps, or elements, that do not materially affect the basic and novel characteristics or function of the item(s) used in connection therewith. For example, trace elements present in a composition, but not affecting the composition's nature or characteristics would be permissible if present under the “consisting essentially of’ language, even though not expressly recited in a list of items following such terminology. When using an open-ended term, such as “comprising” or “including”, it will be understood that direct support should be afforded also to “consisting essentially of’ language as well as “consisting of’ language as if stated explicitly and vice versa. In essence, use of one of these terms in the specification provides support for all of the others.

[0035] For the purposes of the present description and / or claims, and unless otherwise indicated, all numbers expressing quantities, percentages or proportions, and other numerical values used in the specification and claims, are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth herein are approximations that may vary depending upon the desired properties sought to be obtained by the present description, inclusive of the stated value and has the meaning including the degree of error associated with measurement of the particular quantity. The term “about” generally refers to a range of numbers that one of ordinary skill in the art would consider as a reasonable amount of deviation to the recited numeric values (i.e., having the equivalent function or result). For example, this term “about” can be construed as including a deviation of ±10 percent of the given numeric value provided such a deviation does not alter the end function or result of the value. Therefore, a value of about 1% can be construed to be a range from 0.9% to 1.1%.

[0036] The term "and / or" can mean "and" or "or".

[0037] Unless stated otherwise herein, the articles “a” and “the”, when used to identify an element, are not intended to constitute a limitation of just one and will, instead, be understood to mean “at least one” or “one or more”.

[0038] In accordance with the present description, there is provided, in one embodiment, an emulsifier comprising olefinic succinic anhydride (“OSA”) wax, methods of making said emulsifiers, and methods of using said emulsifiers, particularly for the manufacturing of wax emulsions, such as for use in manufacturing wood-based panels.

[0039] It has been found by the present inventors that certain olefinic succinic anhydride (“OSA”) waxes are efficient emulsifiers for use in forming wax emulsions, in particular molten wax emulsions, and more particularly for use in manufacturing wood-based panels. In one embodiment, the inventors have found that OSA wax dispersions are very efficient emulsifiers for molten wax emulsions. The molten wax emulsions stabilized with olefinic succinic anhydride waxes are stable over a period of 15 min at a temperature above the congealing point of the wax and show minimal coalescence and / or creaming. Furthermore, the olefinic succinic anhydride waxes described herein, particularly when used in the concentrations described herein, were found to not affect the water repellency characteristics of the wax while exhibiting no or a minimal degree of foaming when the molten wax emulsion is produced under high shear. As would be understood by personsskilled in art, this characteristic of reduced foaming is desirable in the context of emulsions used for manufacturing wood-based panels.

[0040] As will be appreciated, the waxes that can be used in the manufacturing of wood-based panels may comprise any known waxes that are suitable for such use. For example, such waxes may comprise any natural wax, such as petroleum, vegetable derived waxes, or an animal derived wax, or any synthetic wax, or any combination thereof.

[0041] The presently described olefinic succinic anhydride wax comprises a reaction product of an alphaolefin wax and maleic anhydride. At elevated temperature, the alphaolefin wax (an “ene”) can undergo an ene-reaction with maleic anhydride (the “enophile”). The resulting olefinic succinic anhydride wax is an “ene-product”, with a degree of functionalization that can be adjusted for the intended application. The degree of functionalization is less than or equal to 1 . Preferably, the degree of functionalization ranges from 0.7 - 0.9. The succinic anhydride functionality is predominantly located at the alpha carbon.

[0042] Various commercially available alphaolefin waxes have been found effective for the preparation of olefinic succinic anhydride waxes, resulting in “ene-products” that differ in average molecular weight and degree of functionality. The average molecular weight is determined by the alphaolefin wax used. Suitable alphaolefin waxes include but are not limited to: AlphaPlus™, C30+HA (Chevron Philips); AlphaPlus™ C26-28 (Chevron Philips); Neodene™ C26+ (Shell); Alpha Olefin C20-24 (INEOS); Alpha Olefin C16-18 (INEOS). The average molecular weights of these alphaolefin waxes, as calculated from their carbon chain length distribution measured by gas chromatography, ranges from approximately 230 to 500 g / mol. As discussed above, the functionality of the alphaolefin wax, as expressed by the acid value or AV, is determined by the molar ratio of maleic anhydride to alphaolefin wax used in the ene-reaction. Assuming 1 mole equivalence of maleic anhydride, the AV of the ene- products ranges from about 90 to 170 mg KOH / g. In the presence of moisture, or once added to an aqueous system, the anhydride functionality is lost and a dicarboxylic acid or “diacid-product” is formed. The AV of the diacid-product is approximately double that of the ene-product.

[0043] Olefinic succinic anhydride waxes can be used as emulsifiers to form stable molten wax emulsions. These molecules are sufficiently amphiphilic to be able to form stable emulsions, however, only when the emulsion formulation is amenable towards formation ofan 0 / W emulsion. As known in the art, the phase ratio and addition order should be carefully selected to avoid phase inversion to a water-in-oil (W / O) inverse emulsion. The present inventors have found, for example, that for an olefinic succinic anhydride wax based on AlphaPlus™ C30+ HA, an emulsifier to wax ratio (EWR) of at least 1.0% is required to form a stable molten wax emulsion. The EWR will vary depending on the type of wax and olefinic succinic anhydride wax used.

[0044] An olefinic succinic anhydride wax may be added to a molten wax immediately prior to emulsification to prepare a stable molten wax emulsion. Alternatively, the olefinic succinic anhydride wax can be added to the molten wax and then left to congeal for a period, before re-melting and emulsification. In this manner, a stable molten wax emulsion can be prepared.

[0045] In a preferred embodiment, the olefinic succinic anhydride waxes described herein are used in combination with a water-soluble base. The presence of the base results in saponification of the olefinic succinic anhydride wax, whereby the ene-product or diacidproduct is converted into the corresponding dicarboxylate salt (as further discussed below). The dicarboxylate anion is a more effective emulsifier for molten wax emulsions as the presence of the anionic charge significantly increases the amphiphilicity of the olefinic succinic anhydride wax. This allows for the preparation of molten wax emulsions using a solids content ranging from 20 to 60 w / w%. We have found, for example, that for an olefinic succinic anhydride wax based on AlphaPlus™ C30+ HA, an emulsifier to wax ratio (EWR) of at least 0.15% is required to form a stable molten wax emulsion. This EWR varies depending on the type of wax and olefinic succinic anhydride wax used and typically increases with decreasing molecular weight of the olefinic succinic anhydride wax.

[0046] The olefinic succinic anhydride wax and a base may be added to the molten wax immediately prior to emulsification to prepare a stable molten wax emulsion.Alternatively, the olefinic succinic anhydride wax and base can be added to the molten wax and then left to congeal for a period before re-melting and emulsification.

[0047] In an alternative method, olefinic succinic anhydride wax may be melted in an aqueous phase heated to above the melting temperature of the olefinic succinic anhydride in the presence of a base. The heated aqueous phase is then combined with molten wax to form a stable molten wax emulsion. The hot wax emulsion may then be cooled to form a stable dispersion.

[0048] Additionally, a waxy soap can be prepared by a reaction of the molten olefinic succinic anhydride wax and a base. For example, a molten olefinic succinic anhydride wax can be reacted with monoethanolamine at a temperature above the congealing point of the olefinic succinic anhydride wax and then cooled to obtain a waxy solid. This waxy solid can be melted and dissolved into a molten wax phase or melted and dissolved or dispersed into an aqueous phase and, subsequently, used to emulsify wax to form a stable molten wax emulsion. Furthermore, the molten wax emulsion can be cooled to a stable dispersion..

[0049] In another alternative method, a heated aqueous phase, molten wax phase and olefinic succinic anhydride emulsifier can be combined to form a molten wax emulsion. The components of the molten wax emulsion may be combined in any order or simultaneously. The olefinic succinic anhydride emulsifier can be added in the form of molten olefinic succinic anhydride with or without a base or in the form of a dispersion of olefinic succinic anhydride with a base, as discussed further below.

[0050] Preferred alphaolefin waxes for the preparation of olefinic succinic anhydride waxes for molten wax emulsions are those that are linear and have a carbon chain length distribution ranging from about 20 to about 60 carbons, with a weight average carbon chain length ranging from about 24 to about 36 carbons, and may contain isomers. Preferred alphaolefin waxes thus include AlphaPlus™ C30+ HA, AlphaPlus™ C30+, and AlphaPlus™ C26-28 from Chevron Philips, as well as Neodene™ C26+ from Shell. Other alphaolefin waxes may be used for the preparation of olefinic succinic anhydride waxes for aqueous wax emulsions, however, those are less efficient emulsifiers and require substantially higher EWR to achieve a stable molten wax emulsion.

[0051] Preferred olefinic succinic anhydride waxes for the present description are generally solid at room temperature. The exceptions are those olefinic succinic anhydride waxes derived from alphaolefin waxes that have a carbon chain length distribution positioned largely below the preferred carbon chain length distribution range from about 20 to about 60 carbons or from isomerized alphaolefin waxes. The solid olefinic succinic anhydride waxes described herein have not been used commercially, as they cannot be easily handled or blended at scale to produce an emulsion without heating and melting. We have found, however, that olefinic succinic anhydride waxes can be formulated into a stable aqueous dispersion that can be handled at room temperature and easily introduced to produce a molten wax emulsion at scale.

[0052] Olefinic succinic anhydride waxes can be melted in hot water to form an O / W emulsion under continuous agitation. Upon addition of a water-soluble base and cooling, a stable olefinic succinic anhydride wax dispersion is formed. This dispersion is stable and can be formulated up to about 30 w / w% solids content. The functionality of the olefinic succinic anhydride wax dispersion is comparable to that of the olefinic succinic anhydride wax itself, in that it can be used to formulate a stable molten wax emulsion. For an olefinic succinic anhydride wax dispersion based on AlphaPlus™ C30+ HA, an emulsifier to wax ratio (EWR) of at least 0.38% is required to form a stable molten wax emulsion.

[0053] Additionally, there are known commercial sources of olefinic succinic anhydride. These are generally referred to as alkenyl succinic anhydride (ASA), produced by e.g. Kemira, Akzo Nobel, INEOS, Chevron Philips Chemical, and others. Common examples include octenyl succinic anhydride; C8, NSA (nonenyl succinic anhydride; C9), DDSA (dodecyl succinic anhydride; C12), and ODSA (octadecenyl succinic anhydride; C18). These ASA are manufactured using similar chemistry as described above, from an ene-reaction comprising an olefin and maleic anhydride at high temperature (> 200°C). An example is disclosed in US 4,431 ,826 (the entire contents of which are incorporated herein by reference) which teaches the production of an ASA from straight chain alpha olefins (C13 to C22). Commercial ASAs are generally liquids at room temperature, whereas the olefinic succinic anhydride wax of this invention are waxy solids at room temperature.

[0054] Commercial ASAs can be used in the manufacture of the wax emulsions described herein; however, due to the lower average molecular weight and / or the positioning of the succinic anhydride functionality towards the middle of the carbon chain, stable wax emulsions can only be formulated in the presence of a base and when used at relatively high EWR. Additionally, wax emulsions made with these commercial ASAs are prone to foaming which makes them generally unsuited for the presently described application. For these reasons, ASAs that align with the preferred carbon chain length distribution range from about 20 to about 60 carbons and have the succinic anhydride functionality on the alpha carbon are preferred. An example of such a commercial ASA is GP-104™.

[0055] A structurally related material to ASA is polyolefin-maleic anhydride graft polymer. The graft polymer is produced by grafting at least one maleic anhydride moiety onto a polyethylene or polypropylene backbone such that the maleic anhydride attaches to the polyolefin at any one of the carbon atoms along the length of the polymer. A commercialexample of polyolefin maleic anhydride polymers is Ceramer™ 67. These polymers typically comprise polyethylene or polypropylene and the maleic anhydride is grafted onto the polyethylene or polypropylene through a radical addition which leaves a fully saturated structure and an intact anhydride functionality.

[0056] The olefinic succinic anhydride waxes disclosed herein were found to differ substantially from what has been previously defined for the polyolefin maleic anhydride graft polymer. The chemistry to prepare the olefinic anhydride waxes is different, i.e. an “ene- addition” versus “free radical grafting”. This leads to differences in the structure and properties of the resulting molecules. As compared to the polyolefin maleic anhydride graft polymer, the olefinic succinic anhydride waxes disclosed herein have a lower degree of functionalization, lower average molecular weight, and contain an unsaturation in the molecular structure.

[0057] Additionally, the “ene-product” of the olefinic succinic anhydride waxes ringopens to the “diacid-product” in the presence of moisture, which has an implication for the AV (AV is effectively doubled as a result). The ring-opening process is accelerated by the addition of base. These attributes make these compounds particularly suitable for use as emulsifiers for waxes used as hydrophobing agents in the production of materials such as composite wood panels.

[0058] While the olefinic succinic anhydride emulsifiers and dispersions of same in aqueous alkali have been described in detail for use with molten wax emulsions used in the production of composite wood panels, the emulsifiers describe herein are also contemplated for use with other hydrophobic additives in other applications. For example, olefinic succinic anhydride wax dispersions can be used to produce O / W emulsions of various oils such as naphthenic oils, paraffinic oils, bright stock oil and vegetable oil. These O / W emulsions canbe made without heating the oil as the olefinic succinic anhydride wax is soluble in the oil and will preferentially partition towards the oil-water interphase upon high shear emulsification. As such, stable O / W emulsions can be produced using the olefinic succinic anhydride wax dispersions described herein.EXAMPLES

[0059] Synthesis of olefinic succinic anhydride waxes

[0060] Olefinic succinic anhydride waxes were produced at a total scale of 500 g in a temperature controlled agitated glass reactor. The alphaolefin wax was heated to 80°C until fully melted. Subsequently, 2.0 - 2.8 mole equivalents of maleic anhydride and 0.0011 mole equivalents of Anox™ 20 were added and the reaction mixture heated to 200°C. The amount of maleic anhydride added was dependent up on the C-chain length of the alphaolefin wax. More specifically: 2 eq. for Alpha Olefin C16-18, Alpha Olefin C20-24, AlphaPlus™ C26-28;2.5 eq. for Neodene™ C26+; and 2.8 eq for AlphaPlus™ C30+ HA. The reaction was continued until the conversion (as measured through the washed acid value of the olefinic succinic anhydride wax) plateaued. Various olefinic succinic anhydride waxes were produced, as summarized in Table 1.

[0061] Table 1

[0062] In Table 1 : yield was determined based on a mass balance; AV was measured through titration after washing of the product with acetone; and melting points were measured using DSC.

[0063] Methods

[0064] The acid value (or AV) of the olefinic succinic anhydride waxes was determined by suspending 5 g of polymer into 150 - 200 mL acetone. After continuousagitation for 10 min, the suspension was filtered and the residue washed with acetone and dried to constant weight. A small aliquot (1 g) of the dried material was dissolved in 40 mL hot toluene and titrated with 0.1 N methanolic potassium hydroxide using a phenolphthalein pH indicator.

[0065] Emulsion stability was determined visually by assessing the degree of creaming and coalescence of the hot wax emulsion. 30 mL of hot wax emulsion was measured into a preheated graduated cylinder, which was subsequently submerged into a 80 - 90°C transparent silicone oil bath. A few drops of food colouring were added to the hot wax emulsion to enhance visibility of creaming. The stability of the emulsion was assessed after 15 min, using a qualitative classification for the degree of creaming (“w”) and / or the degree of coalescence (“o”). The classification scale ranges from 0 (no creaming and / or coalescence) to 4 (> 3 mL or > 10% of creaming and / or coalescence).

[0066] 0 = no creaming and / or coalescence

[0067] 1 = < 0.3 mL or < 1% of creaming and / or coalescence

[0068] 2 = 0.3 - 1 mL or 1 - 3% of creaming and / or coalescence

[0069] 3 = 1 mL - 3 mL or 3 - 10% of creaming and / or coalescence

[0070] 4 = (> 3 mL or > 10% of creaming and / or coalescence

[0071] For the present description, a stable wax emulsion is defined as having an emulsion stability classification of 0, 1w, 1o, or 1w 1o.

[0072] Olefinic succinic anhydride wax dispersions

[0073] Olefinic succinic anhydride wax dispersions were prepared by adding a predetermined amount of an olefinic succinic anhydride wax to an aqueous phase (80 - 90°C) containing a base and agitated until fully melted. The resulting emulsion was then agitated under high shear using a Silverson L5M-A mixer and quickly cooled to room temperature.

[0074] Olefinic succinic anhydride wax dispersions were prepared using the different materials listed in T able 1 , targeting a solids content of 20 or 30 w / w% and a base mole equivalency of 1.2. Bases, including sodium hydroxide, potassium hydroxide,monoethanolamine and triethanolamine, were successfully used. These results are summarized in Table 2.

[0075] Table 2

[0076] The results of this experiment demonstrate that olefinic succinic anhydride waxes can be formulated into a stable OSA dispersion.

[0077] Wax emulsion preparation

[0078] Wax emulsions were prepared according to a specified EWR. The olefinic succinic anhydride wax was dissolved into the wax phase, whereas the base was dissolved into the aqueous phase prior to emulsification. The molten wax phase (80 - 100°C) was then emulsified with the aqueous phase (80 - 90°C) under high shear in a Silverson L5M-A at 10,000 rpm for 60 seconds to form a hot wax emulsion. The resulting hot wax emulsion was evaluated for emulsion stability and assigned a qualitative measure of creaming and / or coalescence.

[0079] If an olefinic succinic anhydride wax dispersion is used, the process differs in that the dispersion is added directly to the aqueous phase prior to emulsification with the molten wax. In this scenario, no base is dissolved into the aqueous phase.

[0080] Additionally, the olefinic succinic anhydride wax can be used as the stabilizer without the addition of a base.

[0081] Experiment 1 - Effect of base

[0082] The emulsification power of an olefinic succinic anhydride wax based on AlphaPlus™ C30+ HA (Chevron Philips) and Neodene™ C26+ (Shell) was determined with and without the addition of a monoethanolamine base. All formulations contained 40 w / w% Purewax™ (PetroCanada). These results are summarized in Table 3.

[0083] Table 3

[0084] indicates experiment not done.

[0085] The results of this experiment demonstrate that stable wax emulsions stabilized by olefinic succinic anhydride wax can be prepared both in the presence and absence of a base. The minimum required EWR is dependent on the type of olefinic succinic anhydride wax and the presence of a base. An olefinic succinic anhydride wax based on Neodene™ C26+ was found to be more effective as compared to an olefinic succinic anhydride wax based on Alpha Plus C30+ HA. Furthermore, the EWR can be significantly reduced through the addition of a base. The reaction product of the olefinic succinic anhydride wax and a base is thus a more efficient stabilizer for wax emulsions.

[0086] Experiment 2 - Effect of solids content of the emulsion

[0087] The emulsification power of an olefinic succinic anhydride wax based on AlphaPlus™ C30+ HA (Chevron Philips) was determined with and without the addition of a monoethanolamine base. In the first instance olefinic succinic anhydride was added directed to the molten wax phase without base (w / o base). In the second instance olefinic succinic anhydride was added to the molten wax phase in the presence of MEA (w / MEA) added to the aqueous phase. In the third instance the emulsifier was a dispersion of olefinic succinic anhydride (w / dispersion) prepared as described above. These results are presented in Table 4.

[0088] Table 4

[0089] indicates experiment not done.

[0090] The results of this experiment demonstrate that stable wax emulsions can be formulated up to 60 w / w% solids content in the presence of a base. In the absence of a base, the wax emulsion inverts into an undesired water-in-wax emulsion.

[0091] Experiment 3 - Effect of different olefinic succinic anhydride waxes

[0092] The emulsification power of the various olefinic succinic anhydride waxes was determined with and without the addition of a monoethanolamine base. In the first instance olefinic succinic anhydride was added directly to the molten wax phase without base (w / o base). In the second instance olefinic succinic anhydride was added to the molten wax phase in the presence of MEA (w / MEA) which was added to the aqueous phase. All formulations contained 40 w / w% Purewax™ (PetroCanada). These results are presented in Table 5.

[0093] Table 5

[0094] indicates experiment not done.

[0095] The results of this experiment demonstrate that the formulation of stable wax emulsions is dependent on the average molecular weight of the olefinic succinic anhydridewax used. In particular, the results demonstrate that olefinic succinic anhydride waxes derived from AlphaPlus™ C30+ HA, Neodene™ C26+, AlphaPlus™ C26-28, and GP104™ can be used to formulate stable wax emulsions at an EWR of 0.15 w / w% in the presence of a base. Olefinic succinic anhydride waxes derived from the lower average molecular weight Alpha Olefin C20-24 and C16-18 (INEOS) were found to not form stable wax emulsions at an EWR of 0.15 w / w% .

[0096] Similarly, lower average molecular weight commercial ASAs such as OSA, DDSA, and ODSA can only form stable wax emulsions when used in combination with a base and at substantially high EWR of at least 2.5 w / w%. However, these wax emulsions have a high foaming tendency and are therefore not considered useful in this application. Of the higher average molecular weight ASAs (i.e. ASA 2024™ and GP 104™) GP 104™ was found to perform equivalently to the OSAs described herein. This can be attributed to the similarity in molecular structure between the OSAs and GP 104™, in particular, the relatively high molecular weight and the linear alkyl chain. By contrast, ASA 2024™ is isomerized and was not found to have the same performance characteristics.

[0097] Experiment 4 - Effect of the degree of functionalization

[0098] The emulsification power of olefinic succinic anhydride waxes produced from NC26+ with varying degrees of functionalization was evaluated. These samples were prepared according to the synthesis method described above and by varying the mole equivalent of maleic anhydride. The degree of functionalization is determined by1H-NMR for the sample containing the highest mole equivalent of maleic anhydride (AV = 108 mg KOH / g). The degrees of functionalization of the other samples were calculated from this reference by measuring the corresponding AV. Wax emulsions were prepared using these olefinic succinic anhydride waxes at an EWR of 0.2% using monoethanolamine as the base. The wax emulsions contained 40 w / w% Purewax™ (PetroCanada). The results are summarized in Table 6.

[0099] Table 6| 0.33 | 42 | 4Q |

[0100] The results of this experiment demonstrate that molten wax emulsion stability is dependant on the degree of functionalization as well as the average molecular weight of the olefinic succinic anhydride wax. A low degree of functionalization, despite a suitably high average molecular weight, results in an unstable wax emulsion that coalesces quickly. A high degree of functionalization is beneficial as this allows for the formation of stable hot wax emulsions at the lower EWR. In particular, the results from our testing demonstrated that a degree of functionalization of 0.4 to 1.0, and preferably 0.7 to 0.9 is most beneficial.

[0101] Experiment 5 - Effect of olefinic succinic anhydride wax dispersions

[0102] The emulsification power of the olefinic succinic anhydride wax dispersion based on AlphaPlus™ C30+ HA (Chevron Philips) was determined. All formulations contained 40 w / w% Purewax™ (PetroCanada). While EWR is the ratio of olefinic succinic anhydride to wax, the liquid dosage is the fraction of olefinic succinic anhydride dispersion as part of the hot wax emulsion. The results are presented in Table 7.

[0103] Table 7

[0104] The results of this experiment demonstrate that olefinic succinic anhydride wax dispersions can be used to formulate stable wax emulsions.

[0105] Experiment 6 - Pilot scale testing

[0106] Two olefinic succinic anhydride wax dispersions were evaluated in a pilot scale emulsification setup, and the performance compared against a sodium lignosulfonate. The olefinic succinic anhydride wax dispersions were formulated using olefinic succinic anhydride waxes produced from AlphaPlus™ C30+ HA (Chevron Philips) or Neodene™ C26+ (Shell) and monoethanolamine to a solids content of 25 w / w%. These olefinic succinicanhydride dispersions were then evaluated in the emulsification of a high melt paraffin slack wax at 40 w / w%. The results are presented in Table 8.

[0107] Table 8

[0108] The results of this experiment demonstrate that olefinic succinic anhydride wax dispersions are more effective for formulating stable hot wax emulsions than the industrial standard (sodium lignosulfonate).

[0109] Experiment 7 - Use of a polyolefin-maleic anhydride polymers

[0110] The emulsification power of a polyolefin-maleic anhydride graft polymer (Ceramer™ 67; Nucera Solutions) and a polyolefin-maleic anhydride copolymer (Diacarna™ 30M; Mitsubishi Chemical) was determined. This polyolefin-maleic anhydride graft polymer has an AV of 44 mg KOH / g and a saponification number of 73 mg KOH / g. All formulations contained 40 w / w% Purewax™ (PetroCanada). The results are presented in Table 9.

[0111] Table 9

[0112] The results of this experiment demonstrate that although a polyolefin-maleic anhydride graft polymer such as Ceramer™ 67 or a polyolefin-maleic anhydride copolymer may be used to formulate stable wax emulsions, the performance of these emulsifiers is insufficient as compared to the OSA emulsifiers described herein. For example, for Ceramer™ 67 in all of the samples regardless of the amount of emulsifier added there remains approximately 1% of creaming, even at 5% emulsifier. This factor combined with the expense of these emulsifiers makes these emulsifiers less desirable.

[0113] Experiment 8 - Emulsification of other hydrocarbons

[0114] The emulsification power of the olefinic succinic anhydride wax dispersion based on AlphaPlus™ C30+ HA (Chevron Philips) was determined for various oils. All formulations contained 95 g oil, 5 g of olefinic succinic anhydride wax dispersion, and 200 g water. The olefinic succinic anhydride wax dispersion had a solids content of 25 w / w%. Water and olefinic succinic anhydride wax dispersion were combined. The oil was added under continuous agitation using a Silverson L5M-A at sufficient rpm to emulsify the oil. Stable O / W emulsions (i.e. no creaming or coalescence for a period of 30 min at room temperature) were produced using HYNAP™ N100HTS (San Joaquin Refining Co. Inc.), ARGold™ Legacy (American Refining Group), and RBD soy oil (IMCD).

[0115] This experiment illustrates that the emulsifiers described herein, in particular emulsifiers comprising olefinic succinic anhydride wax dispersions, can be used to form stable emulsions of both waxes and oils (i.e., oil in water emulsions).

[0116] Although the above description includes reference to certain specific embodiments, various modifications thereof will be apparent to those skilled in the art. Any examples provided herein are included solely for the purpose of illustration and are not intended to be limiting in any way. The scope of the claims appended hereto should not be limited by the preferred embodiments set forth in the above description but should be given the broadest interpretation consistent with the present specification as a whole. The disclosures of all prior art recited herein are incorporated herein by reference in their entirety.

Claims

WE CLAIM:1 . An emulsifier for forming a wax or oil in water emulsion, the emulsifier comprising a stable dispersion of olefinic succinic anhydride in water and comprising a base.

2. The emulsifier of claim 1 , wherein the base is present in an amount sufficient to saponify the olefinic succinic anhydride in the aqueous phase.

3. The emulsifier of claim 1 or 2, wherein the base is KOH, NaOH, monoethanolamine (MEA) and / or triethanolamine (TEA).

4. The emulsifier of any one of claims 1 to 3, wherein the olefinic succinic anhydride is in a molten state.

5. The emulsifier of any one of claims 1 to 4, wherein the olefinic succinic anhydride comprises succinic anhydride functionality at the alpha or beta carbon.

6. The emulsifier of any one of claims 1 to 5, wherein the olefinic succinic anhydride comprises a linear alkyl chain.

7. The emulsifier of any one of claims 1 to 6, wherein the olefinic succinic anhydride has a carbon chain length from about 20 to about 60 carbons.

8. The emulsifier of any one of claims 1 to 7, wherein olefinic succinic anhydride has a degree of functionality from about 0.4 to about 1 .0, or from about 0.7 to about 0.9.

9. A stable wax or oil in water emulsion comprising the emulsifier according to any one of claims 1 to 10.

10. The emulsion of claim 9, wherein the emulsion exhibits no or minimal coalescence and / or creaming after 15 minutes at 80 °C.11 . The emulsion of claim 9 or 10, wherein the wax comprises a paraffin wax.

12. The emulsion of any one of claims 9 to 11 , wherein the emulsifier to wax ratio is from about 2.5% to about 0.10%, or from about 1% to about 0.25%.

13. A method of preparing a stable wax or oil in water emulsion comprising: a) providing an emulsifier according to any one of claims 1 to 8; and, b) mixing the emulsifier with a molten wax or with an oil.

14. The method of claim 13, wherein the emulsifier to wax ratio is from about 2.5% to about 0.10%, or from about 1% to about 0.25%.

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