SYSTEM

Field of the Invention [0001] The invention relates to the field of soil or aggregate stabilization, and more particularly to the use of a fast penetrating single component polyurethane prepolymer system for consolidating loose soil and aggregates ( e.g . , rock, coal, mineral), especially in subterranean applications such as tunnels and/or mining. Background of the Invention

[0002] It is known to inject preformed polyurethane prepolymer compounds — or more commonly, simultaneous but separate injections of polyol and polyisocyanate compounds (two-component system) — into soil or other loose aggregates to improve stability. For example, in U.S. Patent No. 3,719,050, Asao et al. disclosed a method for soil stabilization which entailed the injection of polyurethane prepolymer having terminal isocyanate groups, alone or in admixture with water, obtained by the reaction of compounds having at least two terminal hydroxy groups and a polyoxyalkylene chain with polyisocyanate compounds, in a molar amount at least equal to the number of hydroxyl groups and reacting the polyurethane prepolymer with water in the soil to solidify/stabilize/consolidate the soil. However, the polyurethane prepolymer within the cavity has a limited distance of travel upon injection, thus decreasing time efficiency of the project.

[0003] As another example, in U.S. Patent No. 4,113,014, Kubens et al. (Bayer Aktiengesellshaft) disclosed a process for the reinforcement of geological formations and loose rock and earth masses by introducing, into the cavities of the geological formations or rock or earth masses that were required to be reinforced, organic polyhydroxyl compounds and organic poly isocyanates through separate chambers. The constituent compounds reacted in the cavities to form polyurethanes. The reaction process is said to be characterized in that the polyisocyanate component used is a polyisocyanate mixture containing from about 10 to 80%, by weight, of 2,4’- diisocyanato-diphenylmethane. However, as noted, Kubens required the use of a cartridge having two chambers separated from each other, the first chamber containing the polyisocyanate component and the second chamber containing the polyol component. The quantitative proportions of the two components were calculated so that when the cartridge was destroyed, a reaction mixture which reacted to yield a polyurethane was obtained. This two-component type system is disadvantageous due to increased complexity in equipment needed, along with storage and transportation difficulties. Furthermore, very precise quantities of the polyol and polyisocyanate must be used to conduct the appropriate reaction. These precise quantities must be dispensed at the jobsite, thus further relying on the skill of the user/operator.

[0004] In U.S. Patent No. 4,114,382, Kubens et al. (Bayer Aktiengesellshaft) disclosed a further process for consolidating geological formations, heaped rock and earth masses which involved applying a polyurethane reaction system. The reaction system comprised a polyisocyanate component and a polyol component containing 5 to 50 wt.% of a special poly ether with an OH number under about 100. This poly ether was said to be produced by the reaction of a compound having more than one reactive hydrogen atom per molecule and a molecular excess of a 1,2-alkylene oxide. The reaction system could also contain conventional polyurethane additives such as foaming agents, fillers, foam stabilizers and catalysts. In a preferred embodiment, the special poly ether was produced from ethylene diamine or triethanol amine. Kubens also described that in forming the polyurethane, polyols were typically used having an average molecular weight of 400-600 and an OH number of 350-400. These polyols may be replaced up to about 15% or even completely by a plasticizer, such as castor oil. However, castor oils have the disadvantage of relatively high viscosity, which could impede penetration into the smallest cracks and crevices and wetting of the surfaces within the rocks and soil. Furthermore, Kubens also explicitly teaches a two-component type of system where the polyisocyanate and polyol component are injected separately into the geological formations, heaped rock and earth masses.

[0005] In U.S. Patent No. 4,139,676, Janssen et al. (Minnesota Mining and Manufacturing Company) described consolidation of aggregate material whereby superficial aggregate material (e.g., soil and sand) was consolidated by means of a water-insoluble, moisture-curable NCO-terminated prepolymer having defined physical properties. Janssen et al. further indicated that prepolymers are generally very viscous liquids and though they can be used by themselves in its application, it is preferred to employ the same in the form of a solution in a suitable vehicle or solvent which is nonreactive with the isocyanate moiety. Thus, organic solvents, or any other organic compounds, which contain active hydrogen atoms are to be avoided in preparing the fluid agent used herein. Generally speaking, the solvent or vehicle should contain less than 0.05% by weight of water. Generally, these solvents can be either water-miscible or water-immiscible and are preferably volatile at ambient conditions. Representative solvents which can be used include acetone, 2-butanone and other ketones, toluene and other aromatic hydrocarbons, aliphatic hydrocarbons, esters, chlorinated aromatic hydrocarbons and chlorinated aliphatic hydrocarbons, tetrahydrofuran and other known ethers and glycol ethers, dimethyl formamide and other such solvents. See e.g., Col. 2, 11. 20-44.

[0006] In U.S. Patent No. 4,920,192, Wiser-Halladay (ARC) disclosed a method employing what was termed a polyurethane quasi prepolymer for proppant consolidation. This method involved preparing a polyurethane prepolymer for consolidating a proppant in a subterranean formation about a well, employing the improvement characterized by the quasi prepolymer being formed by reacting a diol with a stoichiometric excess of isomeric methylene diphenylene diisocyanate and a diluent; and allowing the reactants to stand for a period in excess of two hours at 25 °C, forming oligomers of polyurethane chains. The method enables consolidating a proppant in fractures by a slow polymerization process, whereby the curing agent can be added at the same time the proppant is placed. Also disclosed are specific examples of diluents and curing agents. Of the diluents, Wiser-Halladay specifically taught use of methyl formamide, propylene carbonate, and dimethyl sulfoxide, all of which are hydrophilic in nature. Their hydrophilicities result in dissolution in water, causing the mixture to potentially flow away from the target region in the proppant.

[0007] As a final example, GCP Applied Technologies Inc. (current applicant hereof) had developed polyurethane foam-based compositions and methodologies used for stabilizing soils in tunnels, excavations, and other subterranean applications. However, improvements can be made and are disclosed herein.

[0008] Accordingly, what are needed are compositions and methodologies for stabilizing loose earthen mass using low-viscosity, water-reactive polyurethane prepolymers. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome.

[0009] All referenced publications are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[0010] While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.

[0011] The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.

[0012] In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.

Summary of the Invention [0013] The long-standing but heretofore unfulfilled need for improved compositions and methodologies for stabilization of loose earthen mass (e.g., soil, rocks, coal, mineral, other aggregates) is now met by a new, useful, and nonobvious invention. [0014] Exemplary embodiments of the current invention are compositions and method for stabilizing loose earthen mass. A single component liquid resin system, including a mixture of polyurethane prepolymers and a hydrophobic plasticizer, is prepared and transported to the jobsite. Additives may optionally be included in the mixture of polyurethane prepolymers and plasticizer. The mixture is injected into the loose earthen mass and comes into contact with water, which causes polymerization and expansion of the resin into a polyurethane foam that stabilizes the loose earthen mass. The resulting foam includes unique properties that facilitate the stabilization.

[0015] An exemplary method of the current invention for stabilizing or reinforcing soil or aggregates in a subterranean formation, comprises: infiltrating into interstices between loose particles of the soil or aggregates, a single component liquid resin system comprising a fluid mixture of polyurethane prepolymers and a hydrophobic, water-insoluble plasticizer; and allowing the infiltrated mixture to remain within the interstices to contact water or moisture, causing polymerization and expansion into a polyurethane foam that stabilizes the loose particles of the soil or aggregates, wherein the polyurethane foam has the following properties: a foam penetration of about 10 mm or less at a force of about 28 N or less, a density of about 30 kg/m ³ or more, a compressive strength of about 30 kPa or more, and a heat production of about 150°C or less upon completion of polymerization. [0016] Another exemplary method of the current invention for stabilizing or reinforcing soil or aggregates in a subterranean formation, comprises: injecting into interstices between loose particles of the soil or aggregates, a single component liquid resin system comprising the following components mixed uniformly together into a pumpable liquid suspension: a polyisocyanate component comprising a methylene diphenylene diisocyanate (“MDI”) compound, a polyol component comprising a polyether polyol compound, wherein the MDI compound is present in an amount of about 40- 70 parts to about 1-20 parts of the poly ether polyol compound, and a hydrophobic, water-insoluble plasticizer component comprising a plasticizer comprising a monoester of benzoic acid and isodecyl alcohol, present in the amount of about 5% to about 80% by weight of the single component liquid resin system; and allowing the infiltrated mixture to remain within the interstices to contact water or moisture, causing polymerization and expansion into a polyurethane foam that stabilizes the loose particles of the soil or aggregates. [0017] An exemplary subterranean soil- or aggregate-stabilizing precursor composition of the current invention, comprises: a single component liquid resin system that includes polyurethane prepolymers and a hydrophobic, water-insoluble plasticizer, wherein the polyurethane prepolymers are formed by reacting polyol polyether with a stoichiometric excess of methylene diphenyl diisocyanate (MDI) to form both urethane linkage therebetween and residual MDI, the MDI compound is present in an amount of about 40-70 parts to about 1-20 parts of the poly ether polyol compound, and the hydrophobic, water-insoluble plasticizer is a plasticizer comprising a monoester of benzoic acid and isodecyl alcohol, present in the amount of about 5% to about 80% by weight of the single component liquid resin system.

[0018] These and other important obj ects, advantages, and features of the invention will become clear as this disclosure proceeds. [0019] The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the disclosure set forth hereinafter and the scope of the invention will be indicated in the claims. Brief Description of the Drawings

[0020] For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawing, in which:

[0021] The Figure is a flowchart depicting a general process utilizing a single component resin system, according to an embodiment of the current invention.

Detailed Description of Exemplary Embodiments

[0022] In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part thereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized, and structural changes may be made without departing from the scope of the invention. [0023] As used in this specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the context clearly dictates otherwise.

[0024] As used herein, “about” means approximately or nearly and in the context of a numerical value or range set forth means ±15% of the numerical. In an embodiment, the term “about” can include traditional rounding according to significant figures of the numerical value. In addition, the phrase “about ‘x’ to ‘y ’” includes “about ‘x’ to about ‘y’”.

[0025] Further, any range of numbers recited in the specification or claims, such as that representing a particular set of properties, units of measure, conditions, physical states or percentages, is intended to literally incorporate expressly herein by reference or otherwise, any number falling within such range, including any subset of numbers within any range so recited. For example, whenever a numerical range with a lower limit, RL, and an upper limit RU, is disclosed, any number R falling within the range is specifically disclosed. In particular, the following numbers R within the range are specifically disclosed: R = RL ± k*(RU-RL), where k is a variable ranging from 1% to 100% with a 1% increment, e.g., kis 1%, 2%, 3%, 4%, 5%. ... 50%, 51%, 52% ... 95%, 96%, 97%, 98%, 99%, or 100%. Moreover, any numerical range represented by any two values of R, as calculated above, is also specifically disclosed.

[0026] In certain embodiments, the present invention teaches a single component water-reactive injection resin for stabilizing or consolidating soil particles, rocks, earth masses, or other loose aggregates in below-grade or subterranean applications, such as tunnels and excavations. In other embodiments, the present invention teaches a process of stabilizing or consolidating soil particles, rocks, earth masses, or other loose aggregates in subterranean applications, comprising sealing, strengthening, and consolidating subterranean structures — including but not limited to tunnels, galleries in mines, and loose strata — by injecting a 1 -component, low viscosity water-reactive polyurethane-based injection resin (see the Figure). Within the context of the present disclosure, the term “aggregates” refers to particles, rocks, earth masses, strata, stones, slag, gravel, or other material that are in need to be stabilized, consolidated, or otherwise reinforced to form a more homogenous structure between the aggregates.

[0027] It should be noted that although the current composition and method are typically most beneficial in below-grade or subterranean applications (e.g., tunnel waterproofing, mining and excavation, etc.), above-grade applications (e.g., cracks or joints in upstanding structures, etc.) are contemplated herein as well.

[0028] Single component systems are desirable as compared to two component systems because less complicated equipment is required, and less heat is evolved as compared to the reaction products of two component systems. Importantly, single component systems offer the possibility of achieving lower viscosity injection resins, which in turn facilitates easier and faster application and permit pumping through hoses over longer distances as compared to two component systems. An exemplary single component injectable resin of the present invention comprises polymeric methylene diphenyl diisocyanate (MDI), reaction products of polymeric MDI and polyols and a plasticizer, and combinations thereof.

[0029] In certain embodiments, the present invention is a water-reactive composition comprising polymeric MDI, polyurethane prepolymers, and a plasticizer, which are injected to seal, consolidate, and strengthen subterranean structures, for example including but not limited to tunnels, mines, soils and loose strata. Certain embodiments of the current invention include single component resins that were surprisingly found to have low viscosity, permitting better permeation and penetration of the injected area or structures. Compared to two component polyurethane injection resins, the current single component resins develop less heat when reacting and curing. As will become more evident as this specification continues, the compositions and methods discussed herein resulted in unique foam properties upon reaction with water and showed low migration values of substances into the environment when in contact with groundwater or any aquifer in the subterranean structure where it was injected.

[0030] Certain embodiments of the invention contemplate the on-site formation of a urethane- or urea-based foam via a single component system comprising urethane or urea prepolymers formed from the reaction of polyols or polyamines in an excess of isocyanates, preferably with a viscosity-decreasing amount of hydrophobic plasticizer. Within the context of the present disclosure, the term “urethane- or urea-based” refers to a composition containing urethane and/or urea linkages. The resulting prepolymer product is cured on site (i.e., at the site of injection or application), where the residual isocyanate reacts with water on site (i.e.. naturally present, pre-injected, or concurrently injected with the prepolymer) to form urea and/or urethane linkages and release carbon dioxide, resulting in the urethane/urea-based foam.

[0031] Within the context of the present disclosure, the term “prepolymers” refers to monomers, oligomers, or polymers that are capable of further polymerization. Accordingly, prepolymers are present in an intermediate molecular mass state prior to being fully cured. Upon addition of a curing agent, reactive agents within the prepolymers continue to polymerize. As such, “polyurethane prepolymers” for example include polyol hydroxyl end groups that have been reacted with isocyanate groups, in turn leaving isocyanate functionality at the termini instead of hydroxyls. To form these polyurethane prepolymers, a reaction of isocyanate and polyols takes place (e.g., within a chemical reactor), where the reaction includes an amount of polyol that is lower than an amount that is stoichiometrically needed to form the full polyurethane polymer. In other words, an excess of isocyanate is reacted with polyols. Upon exposure to water or moisture, polymerization continues, and an expanding polyurethane foam is formed.

[0032] Within the context of the present disclosure, the term “viscosity” refers to a measure of a fluid’s resistance to deformation at a given rate. A liquid with a lower viscosity flows more freely /readily than a liquid with a higher viscosity. Viscosity is typically recorded as centipoise (cps) or mPa-s. The viscosity of a liquid, such as the resin containing prepolymers disclosed herein, may be determined by methods known in the art. Within the context of the present disclosure, viscosity measurements are acquired according to ISO 3219:1993 standards, unless otherwise stated. Furthermore, spindle 2 is used for viscosity measurements, at a speed 60 rpm. Preferably, the resin taught by the present disclosure has a viscosity (at 25°C) of about 200 mPa-s or less, about 180 mPa-s or less, about 160 mPa-s or less, about 140 mPa-s or less, about 120 mPa-s or less, about 100 mPa-s or less, about 80 mPa-s or less, about 60 mPa-s or less, or in a range between any two of these values. Preferably, the viscosity is between about 60 mPa-s and about 200 mPa-s, more preferably between about 125 mPa-s and about 175 mPa-s at 25°C, or even more preferably between about 135 mPa-s and about 160 mPa-s at 25°C.

[0033] Within the context of the present disclosure, the term “plasticizer” refers to materials that can be added before, during, or after the formation of a liquid resin, in order to decrease the viscosity of the resulting resin. Hydrophobic plasticizers, in particular, can be added to alter or improve desirable properties of the resin, for example so that the resin is less likely to wash out or become less diluted when contacting flowing water.

[0034] In exemplary embodiments, the polyurethane prepolymers include isocyanates comprising polymeric MDI, p-phenylenediisocynate (PPDI), isophorone diisocyanate (IPDI), and hydrogenated MDI, among others. Preferably, the isocyanates comprise polymeric MDI, which is also known to one of ordinary skill in the art as crude MDI. Polymeric MDI may include a blend of 0%-80% of 4,4 methylenediphenyl diisocyanate with 20%-100% of isocyanic acid polymethylenepolyphenylene ester, for example including but not limited to diphenylmethane, isomers thereof, homologues thereof, or combinations thereof. As contemplated herein, polyurethane prepolymers can be formed from a reaction of an excess of polymeric MDI with polyamines or more preferably polymeric MDI with polyols.

[0035] Within the context of the present disclosure, the term “excess” refers to an amount of reactant that is beyond what is needed to complete a reaction with a given amount of a limiting reactant. For example, an excess of polymeric MDI may be combined with a given amount of polyether polyol, such that there is residual polymeric MDI remaining after the reaction with the polyol has been completed. This residual isocyanate may then react with water/moisture to form polyurethane/polyurea foam. The excess of polymeric MDI reacted with polyol can be performed at a concentration of about 40-70 parts polymeric MDI reacted with about 1-20 parts of polyol, and preferably about 55-65 parts polymeric MDI reacted with about 5-10 parts of the polyol.

[0036] In exemplary embodiments, the polyurethane prepolymers include polyols comprising, for example, castor oil, polyether polyols, or polyester polyols, among others. Preferably, the polyols comprise polyether polyols, due to better hydrolytic stability of polymers made with poly ether polyols, though other polyols may be utilized as well. Examples of polyether polyols include, but are not limited to, polypropylene oxide homopolymers (PPG polyols), glycerin-based polyethertriols, sucrose-based polyols, sorbitol-based polyols, aminopolyols, Mannich base polyols, or combinations thereof. Of these, the polyether polyol preferably comprises glycerin-based polyethertriols.

[0037] In certain embodiments, the hydroxyl value of the polyols can be in the range of about 100 -700 mg KOH/g, more preferably in the range of about 300-600 mg KOH/g, and even more preferably in the range of about 360-450 mg KOH/g. In certain embodiments, the viscosity of the polyols can be in the range of about 60-40000 mPa- s at 25°C, preferably in the range of about 200-2000 mPa-s at 25°C, and even more preferably in the range of about 300-500 mPa-s at 25°C. In certain embodiments the molecular weight of the polyols can be in the range of about 100-7000 g/mol, more preferably in the range of about 250-2000 g/mol, and even more preferably in the range of about 350-450 g/mol. [0038] As noted previously, use of polyols can be substituted with polyamines, for example being represented by the following chemical structure: where R = C ₂ H ₅ ; n can be in the range of about 1-10, more preferably in the range of about 1-5, and even more preferably equal to 1; and x + y + z can be in the range of about 1-100, more preferably in the range of about 2-85, and even more preferably in the range of about 5-6. The molecular weight of the polyols or polyamines can be in the range of about 100-1000 g/mol, more preferably in the range of about 200-500 g/mol, and even more preferably in the range of about 350-450 g/mol. An example of an amine functional catalyst is diamine, for instance 4,4’-methylenebis(2- chloroanibne) (MBOCA). [0039] Optionally, prior to the addition of the polyol/polyamine to the isocyanate, a stabilizer can be added to avoid gelation of the reaction mixture and improve stability of the resulting prepolymer. The amount of stabilizer depends on the alkalinity of the used polyol. Examples of stabilizers include phosphoric acid (in a concentration of about 80%-100%) and benzoylchloride, among other suitable stabilizers. With the stabilizer added, the reaction components (isocyanate + polyol/polyamine) can be mixed at a given temperature. A catalyst can also be added subsequently, for example including but not limited to organometal compounds, tin catalysts and tertiaire amines for about (2) hours with the temperature maintained at about 75°C-85°C.

[0040] As indicated previously, the urethane- or urea-based prepolymers further include a hydrophobic plasticizer to improve (1) ease of injection, (2) penetration and permeation through the target region by reducing the viscosity (i.e., greater distance traveled by lower viscous liquid), and (3) the hydrophobic character of the liquid during application and upon curing. The enhanced hydrophobic character of the injected/applied liquid composition helps avoid wash out or dilution when the resin is injected into areas with flowing or gushing water, and it will avoid shrinkage of the cured polymer by migration of water soluble ingredients into the environment. The choice of the right plasticizer contributes to the desired foam properties after curing.

[0041] Examples of hydrophobic plasticizers that are contemplated to be used herein include, but are not limited to, phthalates such as diisononylphthalate (DINP) and diisodecylphthalate (DIDP); 1,2 cy cl ohexanedi carboxylic acid, dinonylester, branched or linear (DINCH); citrates such as acetyltributylcitrate; maleates such as diethylmelate, dipropylmaleate, dibutylmaleate, and dipentylmaleate; adipates such as dioctyladipate and dimethyladipate; succinates such as dimethylsuccinate, diisobutylsuccinate, and dioctylsuccinate; butyrates such as 2,2,4 trimethyl-1,3 pentanediol diisobutyrate; propylene carbonate; dibasic ester; sebacates such as dibutylsebacate; benzoates; alkylesters of benzoic acid, such as benzoic acid, C9-C11, branched alkyl esters; dimethylsulfoxide; terephthalates such as dibutyltherephthalate and dioctylterephthalate; or analogs, homologues, and/or combinations thereof. Preferably, the plasticizer comprises phthaltes, terephthalates, citrates, adipates, benzoates, maleates. Even more preferably, the plasticizer comprises benzoic acid, C9- Cll, branched alkyl esters (e.g, a monoester of benzoic acid and isodecyl alcohol (JAYFLEX MB 10)). It is contemplated herein that each of the foregoing plasticizers sufficiently decreases viscosity of the liquid composition that is applied on-site and also is sufficiently hydrophobic for the purposes stated herein. The amount of plasticizer utilized can be about 5-80% by weight, preferably about 15-55% by weight, and even more preferably about 35-45% by weight of the liquid resin system.

[0042] Within the context of the present disclosure, the term “sufficiently hydrophobic” refers to a measurement of the ability of a material or composition to repel water, to the extent that the material helps avoid wash out or dilution when the composition (including the hydrophobic element) is injected into areas with flowing or gushing water, and avoid shrinkage of the cured polymer by migration of water soluble ingredients into the environment.

[0043] Upon preparation of the urethane- or urea-based prepolymer composition, the composition is transported to the jobsite for injection or application to a target region in need of that is in need of solidification, stabilization, consolidation, or reinforcement. To control reaction times and uniform distribution of the foaming resin, when applied in jobsite conditions, an accelerator for reactivity control and surfactants (e.g., silicone surfactant) for uniform foam production, can be added to the present invention. These components are known to the skilled persons in polyurethane technology and comprise catalysts, such as but not limited to tertiary amines, organometal compounds, dibutyltindilaurate, dibutyltinoctoate and polyethersilicones as foam stabilizers. Preferred accelerators are available from GCP APPLIED TECHNOLOGIES under the trade names HA CUT CAT AF and HA CUT CAT SXF AF.

[0044] On application of the prepolymer composition, water reacts with the composition and functions as a curing agent, stimulating expansion of the composition and forming a foam resin. This foam resin has a high compressive strength and stabilizes/reinforces the target region by consolidating soil and/or loose strata and rocks within the target region. It can be understood that the source of water is dependent on need and characteristics of the target region. If the target region has flowing or exposed water, then an external source of water may not be necessary, as the prepolymer composition can react with the water naturally present within the target region. On the other hand, if the target region does not contain available water or moisture, then an external source of water may be used for curing the prepolymer composition.

[0045] Within the context of the present disclosure, the terms “modulus” and “compressive strength” refer to the capacity of a material to withstand loads or forces intended to compress the material. Compressive strength is typically recorded as kPa and may be determined by methods known in the art. Within the context of the present disclosure, compressive strength measurements are acquired according to ISO 844:2014 standards, unless otherwise stated. Preferably, the polyurethane foam taught by the present disclosure has a compressive strength of about 30 kPa or more, 40 kPa or more, 50 kPa or more, 60 kPa or more, 70 kPa or more, 80 kPa or more, 90 kPa or more, 100 kPa or more, 110 kPa or more, or in a range between any two of these values.

[0046] Within the context of the present disclosure, the term “density” refers to a measurement of the mass per unit volume of a material (e.g., foam) or composition (e.g., prepolymer). Herein, the term “density” generally refers to the true density of a polyurethane foam material. Density is typically recorded as kg/m ³ or g/cc. The density of a foam may be determined by methods known in the art. Within the context of the present disclosure, density measurements are acquired according to ISO 845:2006 standards, unless otherwise stated. Preferably, the foam taught by the present disclosure has a density of about 20 kg/m ³ or more, about 30 kg/m ³ or more, about 40 kg/m ³ or more, about 50 kg/m ³ or more, about 60 kg/m ³ or more, about 70 kg/m ³ or more, about 80 kg/m ³ or more, about 90 kg/m ³ or more, or in a range between any two of these values.

[0047] Within the context of the present disclosure, the term “foam penetration” refers to a measurement of the distance that an object can pierce or enter into a foam without damaging or tearing the skin of the foam. Foam penetration is recorded herein in millimeters (mm) and the force at which the skin breaks is recorded in Newtons (N). Unless otherwise stated, the foam penetration is measured herein through indentation of a foam with a test probe. The test probe used herein is a cylindrical stainless steel probe that is about 60 mm long, with a flat contact surface and a diameter of about 15 mm. The probe is fixed to a load cell of about 5000-N capacity, and the penetration rate is 5 mm/min. The test temperature of material and equipment is 23°C + 2°C. Preferably, the foam taught by the present disclosure has a foam penetration of about 10.0 mm or less, about 9.5 mm or less, about 9.0 mm or less, about 8.5 mm or less, about 8.0 mm or less, about 7.5 mm or less, about 7.0 mm or less, about 6.5 mm or less, about 6.0 mm or less, about 5.5 mm or less, about 5.0 mm or less, about 4.5 mm or less, about 4.0 mm or less, about 3.5 mm or less, about 3.0 mm or less, about 2.5 mm or less, or in a range between any two of these values. In preferred embodiments, foam penetration is between about 2.5 mm and about 8.5 mm at a force of about 28 N or less.

[0048] Within the context of the present disclosure, the term “susceptibility to migration into water” refers to the likelihood of a foam’s soluble components migrating into or with water that contacts the foam. Susceptibility to migration into water is recorded herein as mgC/dm ² .day and typically decreases upon subsequent test cycles due to a majority of the soluble components migrating into water during the first test cycle. Within the context of the present disclosure, measurements of susceptibility to migration into water are acquired according to EN 12873-2, unless otherwise stated. Preferably, the foam taught by the present disclosure has a susceptibility to migration into water of about 10 mgC/dm ² .day or less after the first test cycle, 8 mgC/dm ² .day or less, 6 mgC/dm ² .day or less, 4 mgC/dm ² .day or less, 2 mgC/dm ² .day or less, 1 mgC/dm ² .day or less, 0.8 mgC/dm ² .day or less, 0.6 mgC/dm ² .day or less, 0.4 mgC/dm ² .day or less, 0.2 mgC/dm ² .day or less, 0.1 mgC/dm ² .day or less, or in a range between any two of these values.

[0049] Within the context of the present disclosure, the term “heat production” refers to the internal core temperature of a foam upon completion of polymerization (i.e., expansion of foam has ceased). Heat production is typically recorded as °C and is measured by inserting a temperature probe/sensor into the substantial center of the foam. Preferably, the foam taught by the present disclosure has a heat production of about 150°C or less, about 140°C or less, about 130°C or less, about 120°C or less, about 110°C or less, about 100°C or less, about 90°C or less, about 80°C or less, about 70°C or less, about 60°C or less, about 50°C or less, or in a range between any two of these values. In preferred embodiments, heat production is between about 50°C and about 100°C. It should be noted that in many countries, regulations permit up to about 140°C for mining applications, where certain embodiments of the current invention can be effectively utilized. [0050] As indicated previously, additives may be added at certain points during the foregoing process. Within the context of the present disclosure, the term “additive” refers to materials that can be added to a composition before, during, or after production of the prepolymer composition or formation of the foam. Additives can be added to alter or improve desirable properties in the prepolymer composition or in the foam, or to counteract undesirable properties therein. Examples of additives includes, but are not limited to, fillers, UV stabilizers, degassers, antistatic agents, plasticizers, accelerants, catalysts, stabilizers, fire retardants, pH adjusters, reinforcing agents, thickening or thinning agents, elastic compounds, radiation absorbing or reflecting compounds, and other additives known in the art.

[0051] Examples

[0052] While the invention is described herein using a limited number of embodiments, these specific embodiments are not intended to limit the scope of the invention as otherwise described and claimed herein. Modification and variations from the described embodiments exist. More specifically, the following examples are given as a specific illustration of embodiments of the claimed invention. It should be understood that the invention is not limited to the specific details set forth in the examples. All parts and percentages in the examples, as well as in the remainder of the specification, are by percentage weight unless otherwise specified.

[0053] Preparation of Resin Containing Polyurethane Prepolymers

[0054] Example 1. To obtain polyurethane prepolymers according to an embodiment of the current invention, an excess of polymeric MDI (e.g., SUPRASEC 5025, VORANATE M220, or similar) was reacted with a stochiometrically limiting amount of polyether polyol (e.g, DESMOPHEN 1400BT, CARADOL ET380, or similar), at a concentration of about 59.5 parts polymeric MDI reacted with about 4.5 parts of polyether polyol. The polyether polyol was characterized by a hydroxyl value of about 400 mg KOH/g, a viscosity of about 400 mPa-s at 25°C, and a molecular weight of about 420 g/mol.

[0055] The polymeric MDI was mixed with the polyether polyol for about two (2) hours at a temperature of about 75°C-85°C. The head space in the reaction recipient was filled with nitrogen gas to avoid unwanted side reactions of air moisture with the polymeric MDI. After the two (2) hours of mixing at 75°C-85°C, a viscosity -reducing hydrophobic plasticizer comprising a monoester of benzoic acid and isodecyl alcohol (JAYFLEX MB 10) was added at an amount of about 36% by weight.

[0056] Example 2 To obtain polyurethane prepolymers according to an embodiment of the current invention, an excess of polymeric MDI (e.g., SUPRASEC 5025, VORANATE M220, or similar) was reacted with a stochiometrically limiting amount of polyether polyol (e.g., PETOL PZ 4004G or similar), at a concentration of about 59.5 parts polymeric MDI reacted with about 4.4 parts of polyether polyol. The polyether polyol was characterized by a hydroxyl value of about 400-450 mg KOH/g, a viscosity of about 5175 mPa-s at 25°C, and a molecular weight of about 630 g/mol.

[0057] The polymeric MDI was mixed with the polyether polyol for about two (2) hours at a temperature of about 75°C-85°C. The head space in the reaction recipient was filled with nitrogen gas to avoid unwanted side reactions of air moisture with the polymeric MDI. After the two (2) hours of mixing at 75°C-85°C, a viscosity-reducing hydrophobic plasticizer comprising 2,2,4-trimethyl-l,3-pentanediol diisobutyrate was added at an amount of about 36% by weight.

[0058] Example 3 To obtain polyurethane prepolymers according to an embodiment of the current invention, an excess of polymeric MDI (e.g., SUPRASEC 5025, VORANATE M220, or similar) was reacted with a stochiometrically limiting amount of polyether polyol (e.g., PETOL PS 400 4G or similar), at a concentration of about 59.5 parts polymeric MDI reacted with about 4.4 parts of polyether polyol. The polyether polyol was characterized by a hydroxyl value of about 400-450 mg KOH/g, a viscosity of about 4000 mPa-s at 25°C, and a molecular weight of about 630 g/mol.

[0059] The polymeric MDI was mixed with the polyether polyol for about two (2) hours at a temperature of about 75°C-85°C. The head space in the reaction recipient was filled with nitrogen gas to avoid unwanted side reactions of air moisture with the polymeric MDI. After the two (2) hours of mixing at 75°C-85°C, a viscosity-reducing hydrophobic plasticizer comprising 2,2,4-trimethyl-l,3-pentanediol diisobutyrate was added at an amount of about 36% by weight.

[0060] Example 4 To obtain polyurethane prepolymers according to an embodiment of the current invention, an excess of polymeric MDI (e.g., SUPRASEC 5025, VORANATE M220, or similar) was reacted with a stochiometrically limiting amount of poly ether polyol (e.g., PETOL PM 410N or similar), at a concentration of about 59.5 parts polymeric MDI reacted with about 4.4 parts of polyether polyol. The polyether polyol was characterized by a hydroxyl value of about 400-440 mg KOH/g, a viscosity of about 10400 mPa-s at 25°C, and a molecular weight of about 530 g/mol.

[0061] The polymeric MDI was mixed with the polyether polyol for about two (2) hours at a temperature of about 75°C-85°C. The head space in the reaction recipient was filled with nitrogen gas to avoid unwanted side reactions of air moisture with the polymeric MDI. After the two (2) hours of mixing at 75°C-85°C, a viscosity-reducing hydrophobic plasticizer comprising 2,2,4-trimethyl-l,3-pentanediol diisobutyrate was added at an amount of about 36% by weight.

[0062] Example 5 To obtain polyurethane prepolymers according to an embodiment of the current invention, an excess of polymeric MDI (e.g., SUPRASEC 5025, VORANATE M220, or similar) was reacted with a stochiometrically limiting amount of polyether polyol (e.g., PETOL PA450-3T or similar), at a concentration of about 59.5 parts polymeric MDI reacted with about 4.4 parts of polyether polyol. The polyether polyol was characterized by a hydroxyl value of about 400-500 mg KOH/g, a viscosity of about 380 mPa-s at 25°C, and a molecular weight of about 375 g/mol.

[0063] The polymeric MDI was mixed with the polyether polyol for about two (2) hours at a temperature of about 75°C-85°C. The head space in the reaction recipient was filled with nitrogen gas to avoid unwanted side reactions of air moisture with the polymeric MDI. After the two (2) hours of mixing at 75°C-85°C, a viscosity-reducing hydrophobic plasticizer comprising 2,2,4-trimethyl-l,3-pentanediol diisobutyrate was added at an amount of about 36% by weight.

[0064] Example 6 (comparative). As a reference, polymeric MDI (e.g., SUPRASEC 5025, VORANATE M220, or similar) was not reacted with a stochiometrically limiting amount of poly ether polyol. The polymeric MDI was stored for about two (2) hours at a temperature of about 75°C-85°C. The head space in the reaction recipient was filled with nitrogen gas to avoid unwanted side reactions of air moisture with the polymeric MDI. After the two (2) hours of mixing at 75°C-85°C, a viscosity-reducing hydrophobic plasticizer comprising 2,2,4-trimethyl-l,3-pentanediol diisobutyrate was added at an amount of about 36% by weight vs about 64% of polymeric MDI.

[0065] Example 7 (comparative]. As a negative reference, an excess of polymeric MDI (e.g., SUPRASEC 5025, VORANATE M220, or similar) was reacted with a stochiometrically limiting amount of polyether polyol (e.g, DESMOPHEN 1400 BT, PETOL 400-3 or similar), at a concentration of about 59.5 parts polymeric MDI reacted with about 4.5 parts of polyether polyol. The polyether polyol was characterized by a hydroxyl value of about 400 mg KOH/g, a viscosity of about 400 mPa-s at 25°C, and a molecular weight of about 420 g/mol.

[0066] The polymeric MDI was mixed with the polyether polyol for about two (2) hours at a temperature of about 75°C-85°C. The head space in the reaction recipient was filled with nitrogen gas to avoid unwanted side reactions of air moisture with the polymeric MDI. After the two (2) hours of mixing at 75°C-85°C, a viscosity-reducing hydrophilic plasticizer comprising propylene carbonate was added at an amount of about 36% by weight.

[0067] Characterization of Polyurethane Prepolymers

[0068] % weight. The polyurethane prepolymers — containing a reaction mixture of isocyanates, polyols, and plasticizers — is characterized by about 59.5% isocyanate by weight, about 4.5% polyol by weight, and about 36.0% plasticizer by weight.

[0069] Viscosity. Brookfield viscosity was measured according ISO 3219: 1993 and was found to be about 135-160 mPa-s at 25°C for the polyurethane prepolymers, inclusive of the isocyanates, polyols, and plasticizers.

[0070] Start of the reaction. For each of the examples described above, about 50 grams of the polyurethane prepolymers were mixed with about 5 grams of an accelerator, such as HA CUT CAT AF made by GCP APPLIED TECHNOLOGIES. Subsequently, about 2 grams of water was added, and the mixture was stirred until foaming started; the time between the addition of water and the start of the reaction is reported in Table 1. The progress of the foaming was visually monitored until the expansion stopped; Table 1 further indicates the time between the addition of water and the end of the foaming, which is reported as the end of the reaction. [0071] On-Site Application

[0072] The prepared resin comprising the polyurethane prepolymers are subsequently transported to the jobsite and injected into the target region. As indicated previously, the source of the curing agent, water/moisture, is dependent on the nature of the target region (i.e.. whether water/moisture is naturally present in the target region).

[0073] Characterization of Cured Foam and Foam Quality

[0074] Foam Penetration. Foam penetration was measured through indentation with a test probe. A foam of the prepared resin was made by mixing about 50 grams resin with about 5 grams accelerator (HA CUT CAT AF) in an open cup. Subsequently, about 2 grams water was added, and the liquid was stirred with a wooden spoon until the foaming (i.e.. expansion) started. The foam was allowed to rise/expand, and after curing, the foam was stored in lab conditions at about 20°C-22°C at approximately 50% relative humidity (RH) for 24 hours. For example, the cured foam of Example 1 was found to have an indentation of about 1.5-3.5 mm at a maximum force of about 20-25 N.

[0075] In another test for foam penetration using a different accelerator, a foam of the prepared resin was made by mixing 50g resin with 5g of HA CUT CAT SXF AF. Subsequently, about 2g water was added, and the liquid was stirred with a wooden spoon until the foaming (i.e. , expansion) started. The foam was allowed to cure at about 20°C-22°C at approximately 50% RH for 24 hours. For example, the cured foam of Example 1 was found to have an indentation of about 7-10 mm at a maximum force of 25-30 N.

[0076] Foam Density and Compressive Strength. Foam density was measured according ISO 845:2006, and compressive strength was measured according ISO 844:2014. The foam was prepared as follows: about 125 grams of the prepared resin was mixed in an open cup with about 12.5 grams accelerator, preferably HA CUT CAT AF or HA CUT CAT SXF AF. Subsequently, about 6.25 grams water was added to the mixture, followed by 15 seconds of mixing with an overhead stirrer at 1000 rpm. A cylindrical tube with a diameter of about 10 cm and a height of about 40 cm was placed over the recipient, allowing the foam to rise within the cylinder. The foam was allowed to cure at about 20°C-22°C at approximately 50% RH for 24 hours. Subsequently, the foam cylinder is cut to form test foam cylinders each having a height of about 10 cm. The compressive strength was measured at 10% deformation.

[0077] Using Example 1 as an example, the foam that was prepared with HA CUT CAT AF as accelerator has a foam density of about 35-45 kg/m ³ measured according ISO 845:2006 and a compressive strength of about 30-35 kPa measured according to ISO 844:2014. The foam of Example 1 that was prepared with HA CUT CAT SXF as accelerator has a foam density of about 30-40 kg/m ³ measured according ISO 845:2006 and a compressive strength of about 40-50 kPa measured according to ISO 844:2014.

[0078] Susceptibility to Migration into Water. Foams according to certain embodiments of the current invention were characterized for the susceptibility to migration of soluble components into water. Migration was measured in accordance with EN 12873-2. A foam of the prepared resin was made by mixing about 50 grams resin with about 5 grams accelerator (HA CUT CAT AF) in an open cup. Subsequently, about 2 grams water was added, and the liquid was stirred with a wooden spoon until the foaming (i.e.. expansion) started. The foam was allowed to rise/expand, and after curing, the foam was stored in lab conditions at about 20°C-22°C at approximately 50% RH for 24 hours. For example, the migration of the foam of Example 1 measured according to EN12873-2 was found to be less than about 20 mgC/dm ² .day after the first test cycle, less than about 2 mgC/dm ² .day after the second test cycle, and less than about 1 mgC/dm ² .day after the third test cycle.

[0079] Heat Production. Transition of the prepared resin to a foam was characterized for heat production during the curing and foaming of the resin, by measuring the internal core temperature during foaming (expansion). A foam of the prepared resin was made by mixing about 50 grams resin with about 5 grams accelerator (HA CUT CAT SXF or HA CUT CAT AF) in an open cup. Subsequently, about 2 grams water was added, and the liquid was stirred with a wooden spoon until the foaming (i.e.. expansion) started. The foaming was visually observed, and at the moment when the foam stops rising, a 20-cm probe was inserted into the center of the foam, measuring the internal core temperature. For example, the internal core temperature of the foam of Example 1 was measured to be about 65-75°C. [0080] Table 1 provides an overview of the prepolymer properties and foam properties of the listed examples:

Table 1.

[0081] The foregoing examples and embodiments were present for illustrative purposes only and not intended to limit the scope of the invention.

[0082] The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

[0083] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.