CA2809376A1 - Non-aqueous colloidal dispersion spray foams - Google Patents

Abstract

Spray foams formed from a non-aqueous foamable composition are provided. The foams are formed by destabilizing a colloidal dispersion of dry polymer or resin to allow the coagulatable polymer to form a film aided by a crosslinked structure formed by a crosslinking reactant system having first and second reactants with multiple functional groups that crosslink quickly at or about room temperature. An A-side contains includes a solid, colloid-forming polymer, a multifunctional acid, and a liquid blowing agent as the non aqueous serum phase; and a B-side contains a polyfunctional aziridine crosslinking agent a plasticizer having no acidic protons. The polyfunctional aziridine crosslinking agent may be diluted by a plasticizer, which reduces the viscosity of the B-side. A lack of water or small amount of water in the inventive foam composition permits the foam to be sprayed at temperatures below freezing and to a greater thickness compared to watercontaining compositions.

Description

TITLE OF THE INVENTION

NON-AQUEOUS COLLOIDAL DISPERSION SPRAY FOAMS

BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to spray foams that are used to fill cavities and/or cracks, crevices and gaps to enhance the sealing and insulating properties of buildings and, more particularly, to non-aqueous-based colloidal dispersion foams useful at low temperatures without freezing.

[0002] Spray foams have found widespread utility in the fields of insulation and structural reinforcement. For example, spray foams are commonly used to insulate or impart structural strength to items such as automobiles, hot tubs, refrigerators, boats, and building structures. In addition, spray foams are used in applications such as cushioning for furniture and bedding, padding for underlying carpets, acoustic materials, textile laminates, and energy absorbing materials. Spray foams are also used as insulators or sealants for home walls.

[0003] Two main classes of spray foams are well characterized: polyurethane (non-aqueous) and latex (aqueous). Typically, polyurethane spray foams are formed from two separate components, commonly referred to as an "A" side and a "B" side, that react when they come into contact with each other. The first component, or the "A" side, contains an isocyanate such as a di- or poly- isocyanate that has a high percent of reactive isocyanate ( ¨ N=C=O or "NCO") functional groups on the molecule. The second component, or "B" side, contains nucleophilic reagents, silicone-based surfactants, blowing agents, catalysts, and/or other auxiliary agents. The nucleophilic reagents are generally polyols that include two or more hydroxyl groups, primary and secondary polyamines, and/or water. Preferably, mixtures of diols and triols are used to achieve the desired foaming properties. The overall polyol hydroxyl number is designed to achieve a 1:1 ratio of first component to second component (A:B).

[0004] U.S. Patent No. 5,444,099 to Abe et al., U.S. Patent No. 4,945,120 to Kopp et al.
and U.S. Patent No. 3,984,360 to Galbreath et al. disclose polyurethane spray foams which may be capable of being applied at low temperatures. The polyurethane foams in each these patents require a polyisocyanate component.

[0005] Known polyurethane spray foams exhibit a number of problems. First, they contain high levels of reactive isocyanates, such as methylene-diphenyl-di-isocyanate (MDI) monomers. When the foam reactants are sprayed, the MDI monomers form droplets that may be inhaled by workers installing the foam if stringent safety precautions are not followed. Even a brief exposure to isocyanate monomers may cause difficulty in breathing, skin irritation, blistering and/or irritation to the nose, throat, and lungs; and extended exposure can lead to serious sequelae, including asthmatic-like reactions and possibly death.
Secondly, residual polymeric methylene-diphenyl-di-isocyanate (PMDI) that is not used has an NCO
of about 20%
and is considered to be a hazardous waste that can remain in a liquid state in the environment for years. Therefore, specific procedures must be followed to ensure that the PMDI
waste product is properly and safely disposed of in a licensed land fill. Such precautions are both costly and time consuming.

[0006] In this regard, attempts have been made to reduce or eliminate the presence of isocyanate in spray foams and/or reduce or eliminate isocyanate emissions by spray foams into the atmosphere via the use of latex-based spray foams. Some examples of such attempts are set forth below.

[0007] U.S. Patent Publication Nos. 2008/0161430; 2008/0161431; 2008/0161433;

2008/0161432; 2009/0111902; and 2010/0175810 to Korwin-Edson et al. disclose a room temperature crosslinked latex foam, such as for filling cavities and crevices.
The foam contains a first component that includes a functionalized latex (typically the A side) and a second component that contains a crosslinking agent (typically the B-side), and optionally, a non-reactive resin (e.g., a non-functionalized latex). Either or both the A-side or the B-side may contain a blowing agent package. Alternatively, the A-side and the B-side may each contain a component such as an acid and a base that together form a blowing agent package. A plasticizer, a surfactant, a thickener, and/or a co-solvent may optionally be included in either the A- and/or B-side.

[0008] U.S. Patent Publication No. 2007/0290074 to Dansizen et al. teaches a method for the rapid insulation of expanses. The method utilizes a two-part spray foam system that may be applied at low temperatures; however, the chemicals must reach 70-85 F for proper performance, and the system utilizes heated spraying hoses to heat the material for application at low temperatures.

[0009] U.S. Patent Publication No. 2006/0047010 to O'Leary teaches a spray polyurethane foam that is formed by reacting an isocyanate prepolymer composition with an isocyanate reactive composition that is encapsulated in a long-chain, inert polymer composition.
The isocyanate prepolymer composition contains less than about 1 wt% free isocyanate monomers, a blowing agent, and a surfactant. The isocyanate reactive composition contains a polyol or a mixture of polyols that will react with the isocyanate groups and a catalyst. During application, the spray gun heats the polymer matrix, which releases the polyols and catalyst from the encapsulating material. The polyols subsequently react with the isocyanate prepolymer to form a polyurethane foam.

[0010] U.S. Patent No. 7,053,131 to Ko, et al. discloses absorbent articles that include super critical fluid treated foams. In particular, super critical carbon dioxide is used to generate foams that assertedly have improved physical and interfacial properties.

[0011] There are problems associated with latex spray foams as well. For instance, the processing of spray foams on site may be affected by inclement weather, which results in significant economic losses. One serious disadvantage of known spray foam systems (both latex and polyurethane) is that they can only be used at ambient temperature above about 10 C (50 F). If the surface to be insulated is too cold, it rapidly draws the heat of reaction away from the first layer of the foamable reaction mixture sprayed to the surface. This results not only in an increased density, but also embrittlement of the foam through incomplete reaction. The brittleness of the foam at its initial contact layer is the main reason for loss of favorable adhesion properties to the substrate, which the foam system shows when processed on substrate materials which are at too low a temperature.

[0012] Another disadvantage with latex spray foams is that the foams contain water. The presence of water in the foams results in several problems. First, at low temperatures, the water in the spray foams can freeze, thereby disrupting the quality of the foam itself. Second, the water often causes the latex to be an open-celled foam of high density. Third, because the water takes time to drain or evaporate away, the foam cannot be sprayed to any great thickness. The foam cannot support its own weight (due to the water) and it therefore slides down a wall under its own weight before it becomes set. Finally, for typical acid-base blowing agents, which contain sodium bicarbonate, sodium is present in the final form and promotes hydrophilicity, which compounds these water-related problems.

[0013] A third spray foam option is a plastisol. A typical plastisol is an emulsion that uses plasticizer in the serum phase. Plastisols, however, require considerable heat to coagulate and form a film, since the plasticizer must be absorbed into the lattice to create a continuous plastic phase. Temperatures in excess of 200 F are typically required for plastisols to coagulate.

[0014] Despite these attempts, there remains a need in the art for a spray foam that is non-toxic and environmentally friendly and that may be applied at low temperatures.

SUMMARY OF THE INVENTION

[0015] It is an object of the present invention to provide a non-toxic and environmentally friendly, spray foam composition that is capable of being applied at low temperatures to form a foamed product, which is also an aspect of the invention. It may be applied as a two part (A-side and B-side) composition or as a single composition with reactants segregated from one another until application of the foamable composition.

[0016] Accordingly, in one aspect the invention provides a non-aqueous foamable composition comprising:
a solid, coagulatable polymer colloidally dispersed in a non-aqueous, vaporizable serum phase, optionally with a surfactant; and a crosslinking reactant system comprising at least first and second members of a reactant pair, each member having multiple reactive groups characterized such that, upon combination at or about room temperature, the reactive groups of one member crosslink with the reactive groups of at least the other member to form a polymeric crosslinked structure upon which the polymer forms a film as it coagulates. Generally the first and second members of the crosslinking reactant pair are isolated from one another until combination.

[0017] In another aspect, the invention includes a foamed product comprising:
a crosslinked structure formed by the reaction of at least first and second reactants of a crosslinking reactant system, each having multiple reactive groups characterized such that, upon combination at or about room temperature, the reactive groups of one member crosslink with the reactive groups of at least the other member to form a polymeric crosslinked structure;
a polymeric film coagulated on the polymeric crosslinked structure formed; and a gas generated by vaporization of the non-aqueous serum phase and entrained by the polymeric film.

[0018] For both the foamable composition and the foamed product, the crosslinking system generally comprises first and second reactant pair members that may be selected from the following pairs:
(a) a polyfunctional aziridine and a poly(carboxylic) acid;
(b) a poly(isocyanate) oligomer and a poly(hydroxyl) alcohol; and (c) a poly(amine) and a poly(epoxy) oligomer.

[0019] In certain embodiments using a poly(carboxyl) acid, the acid may be a dry acid powder without chemically bound water. In certain embodiments, one reactant of said crosslinking reactant system may be in the form of a secondary emulsion added separately to the non-aqueous serum phase. In certain embodiments, the composition is substantially free of water.

[0020] In certain embodiments, the non-aqueous foamable composition further comprises a plasticizer. In embodiments with a plasticizer, the plasticizer may be selected from a benzoate ester, triethyl citrate, a tributyl citrate, polyethylene glycol, an octylphenoxypolyethoxyethanol, butyl benzoate and combinations thereof.

[0021] The non-aqueous foamable composition may be prepared such that the first and second reactant members of the crosslinking reactant system are provided in separate dispersions, one member being dispersed in the non-aqueous, vaporizable serum phase along with the coagulatable polymer (A-side), and the other reactant member being dispersed in the plasticizer (B-side). The foamed product is prepared by mixing the separate dispersions.

[0022] This one aspect of the invention includes a two-part non-aqueous foamable composition for forming a foam comprising:
a first component including a lattice phase formed of at least one dry, coagulatable polymer in a liquid blowing agent; a multifunctional acid; and a surfactant;
and a second component including a polyfunctional aziridine crosslinking agent that crosslinks at or about room temperature; and a plasticizer, wherein said plasticizer has no acidic protons to react with said polyfunctional aziridine crosslinking agent.

[0023] In many embodiments, both the foamable composition and the foamed product further comprise a film surfactant. This is generally in addition to colloid surfactant that typically comes as part of colloidally dispersed resins useful in the invention.

[0024] In yet another aspect, the invention provides a method of forming a foam comprising:

combining (a) a solid, coagulatable polymer colloidally dispersed in a non-aqueous, vaporizable serum phase, optionally with a surfactant, with (b) at least first and second members of a reactant pair of a crosslinking reactant system, each member having multiple reactive groups characterized such that, upon combination at or about room temperature, the reactive groups of one member crosslink with the reactive groups of at least the other member to form a polymeric crosslinked structure, to form (c) a reaction mixture;
applying said reaction mixture to a desired location; and destabilizing the lattice of the colloidal dispersion, whereby the coagulatable polymer begins to coagulate and form a film on the crosslinked structure while said non-aqueous serum phase vaporizes to form a gas that is entrained by the polymeric film.

[0025] In certain embodiments, the lattice of the colloidal dispersion is destabilized by vaporizing the non-aqueous serum phase to concentrate the colloid and begin coagulation of the polymer. The non-aqueous serum phase may be selected to have a boiling point such that it vaporizes at ambient application temperature and atmospheric pressure; and the method then further comprises pressurizing said colloidal dispersion prior to application to avoid premature vaporization. The method may also comprise heating the reaction mixture to a temperature above the boiling point of said non-aqueous serum phase to vaporize said non-aqueous serum phase.

[0026] As with the foamable compositions described above, crosslinking structure reactants may be kept in separate dispersions: as in A-side and B-side dispersions. Thus, the method step of combining (a) a solid, colloid-forming polymer dispersed in a non-aqueous serum phase, optionally with a surfactant, with (b) first and second reactants of a crosslinking reactant system may further comprise mixing an A-side dispersion with a B-side dispersion, wherein said A-side dispersion contains the colloid-forming polymer and a one reactant of the crosslinking reactant system dispersed in a non-aqueous serum phase, and the B-side dispersion contains the other reactant of the crosslinking reactant system dispersed in a plasticizer.

[0027] An advantageous feature of these methods is that the reaction mixture may be applied at a temperature near or below freezing since there is no water to freeze and prevent useful foam formation.

[0028] The foams of the present invention may be used to insulate buildings such as homes from temperature fluctuations outside of the building's envelope. The foams may serve both as a conductive and a convective thermal barrier. The foams of the present invention may also serve as a sealant or barrier to air infiltration by filling cracks and/or crevices in a building's roof or walls. Additionally, the foams may be used to form a barrier to seal cracks or crevices around doors, windows, electric boxes, and the like.

[0029] The inventive foams do not release any harmful vapors into the air when applied or sprayed. As a result, the inventive foams reduce the threat of harm to individuals working with or located near the foam. In addition, the application of the foams is more amenable to the installer as he/she will not need to wear a special breathing apparatus during installation.

[0030] It is an advantage of the present invention that the inventive foams do not contain the harmful chemicals found in known polyurethane spray foams, such as, for example, isocyantes like MDI monomers. Therefore, the foams of the present invention do not contain harmful vapors that may cause skin or lung sensitization or generate toxic waste.

[0031] It is also an advantage that the inventive foams do not emit harmful vapors into the air when the foam is sprayed, such as when filling cavities to seal and/or insulate a building.
The inventive foams are safe for workers to install and, therefore, can be used both in the house renovation market and in occupied houses. Additionally, because there are no harmful chemicals in the inventive foams, the foams can be safely disposed without having to follow any stringent hazardous waste disposal precautions.

[0032] It is a further advantage of the present invention that the foam could be dispensed in a pressurized aerosol form from a can or canister depending on the choice of blowing agent/propellant.

[0033] It is also an advantage of the present invention that the blowing agent can vaporize quickly and leave no liquid residue, unlike water, which has to diffuse slowly.

[0034] The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows.

DETAILED DESCRIPTION OF THE INVENTION

[0035] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. All references cited herein, including published or corresponding U.S. or foreign patent applications, issued U.S. or foreign patents, and any other references, are each incorporated by reference in their entireties, including all data, tables, figures, and text presented in the cited references.

[0036] The term "R-value" is the commercial unit used to measure the effectiveness of thermal insulation and is the reciprocal of its thermal conductance which, for "slab" materials having substantially parallel faces, is defined as the rate of flow of thermal energy (BTU/hr or Watt) per unit area (square foot = ft2 or square meter =m2) per degree of temperature difference (Fahrenheit or Kelvin) across the thickness of the slab material (inches or meters).
Inconsistencies in the literature sometimes confuse the intrinsic thermal properties resistivity, r, (and conductivity, k), with the total material properties resistance, R, (and conductance, C), the difference being that the intrinsic properties are defined as being per unit thickness, whereas resistance and conductance (often modified by "total") are dependent on the thickness of the material, which may or may not be 1 unit. This confusion, compounded by multiple measurement systems, produces an array of complex and confusing units the most common of which are:

English Metric/SI units (inch-pound) Intrinsic resistivity, r hr*ft2* F K*m (conductivity, k, is reciprocal) BTU*in W
Total material resistance, R hr*ft2*0F K*m2 (conductance, C, is reciprocal) BTU W

[0037] For ease of comparisons of materials of differing thicknesses, the building industry sometimes reports thermal resistance (or conductance) per unit thickness (e.g. per inch) effectively converting it to thermal resistivity (conductivity), but retains the traditional symbol, R
or R-value.

[0038] With regard to dispersions of one phase (the "dispersed" phase) in another medium or vehicle (the "continuous" phase or "serum"), the following terms and definitions may be used. Dispersions may be categorized on the basis of the physical state of the continuous phase or serum, the physical state of the dispersed phase, and the size of the dispersed phase.
For example, a liquid-in-liquid dispersion of immiscible liquids is an "emulsion", a gas dispersed in a solid or a liquid is a "foam", and a solid particle dispersed in a liquid would be a "suspension" or a "colloid", depending on the size of the dispersed particle.
Certain dispersions according to the present invention are colloids, i.e. solids dispersed in liquids, in which the solid particle remains dispersed (except upon centrifugation) as a result of Brownian motion. In colloids, the dispersed phase is generally of a particle size between about 10-4 and 10-8 cm, more typically between about 10-5 and 10-7 cm. Particles larger than this tend to form suspensions which will settle under gravity alone; while particles smaller than this tend to form solutions which remain dispersed even with centrifugation.

[0039] A "latex" refers to a dispersion of a solid polymer in an aqueous medium.
Generally the polymer has a Tg less than about 20 C, usually lower than about 10 C, and typically the particles of polymer are of a size that makes a latex a colloidal dispersion. Latices or latexes are plural forms of latex. Paint is an example of a colloidal latex. "Lattice", on the other hand, refers to a 3-dimensional structure that dispersed particles may exhibit in the continuous phase based on forces such as electrical charges, hydrogen bonding or van der Waal's forces. In many cases the nature and stability of this lattice is dependent on concentration of dispersed phase (i.e. how densely packed it is), and on the pH and viscosity of the continuous phase, exposure (or not) of functional groups such as by the presence or absence of a surfactant or emulsifier.

[0040] The present invention relates to a non-aqueous colloidal dispersion spray foam that is suitable for use at low temperatures (e.g. , temperatures below freezing). The inventive foams may be used like other foams to seal cracks and crevices of buildings, such as those around windows and doors, to improve sealing and insulation properties.

[0041] In one exemplary embodiment, the inventive foam is formed from two components, namely, a first component or A-side, and a second component or B-side. In particular, the A-side of the foam composition includes a colloid-forming resin or polymer dispersed a non-aqueous serum phase, typically a volatile blowing agent. Other components that may also be included in the A-side include a surfactant, a multifunctional acid, a crosslinker catalyst, and/or a nucleating agent. The B-side contains a polyfunctional aziridine crosslinking agent and a plasticizer, and optionally a surfactant, a filler, a nucleating agent, and a non-reactive resin.

[0042] In the inventive spray foam, a colloidal dispersion is created with a liquid blowing agent as the serum phase. When the dispersion reaches the boiling point of the blowing agent, the blowing agent vaporizes, thereby concentrating and destabilizing the lattice structure of the colloidal polymer, causing the dispersion to coagulate and form a film. At the same time, the vaporized serum phase (as a gas) becomes entrained as bubbles in the polymer matrix to form a foam. Additionally, the foamable composition contains a crosslinking reactant system that creates a crosslinked structure. Without intending to be bound by any particular theory, it is believed that the crosslinking reactants form a "skeleton" or "scaffold" to enhance and maintain the structure of the foam as the resin is coagulating to form the film. For best results, it is thought to be important that the process of scaffold / crosslinked structure formation coincide with the process of film formation. In general, the crosslinking reactant system comprises at least first and second reactant members that each have multiple reactive or functional groups disposed on backbones. The reactive groups react quickly at or about room temperature to form the three dimensional structure on which the film forms. More detail is provided below.

[0043] In exemplary embodiments, the foams of the present invention, as well as the components thereof, meet certain performance properties, or Fitness for Use ("FFU") criteria, both chemical and physical. In particular, desired criteria or FFUs that the inventive foam should meet are set forth in the table below:

Chemical Criteria Physical Criteria = The foam should adhere to various = The foam weight should be between about materials such as wood, metal, 0.5 and about 30.0 pounds per cubic foot concrete and plastic = The foam should be fluid enough to be = The chemical constituents should be as sprayed either at room temperature or by safe as possible. If a hazardous heating (viscosity of <10,000 cP at a high chemical is used, it should not be shear rate) introduced or atomized into the air = The foam should not sag or fall in the cavity where it can be inhaled = The foam should fill in cracks and crevices = The foam may be chemically foamed or be used to coat the cavity with an air through the use of a blowing agent or barrier it may be mechanically foamed with a = Ideally, the cell structure of the foam (closed gas vs. open) should be a mixture of both a = The installer of the foam should be closed and open cell structure to provide able to work with the material without appropriate material properties to achieve any specialized personal protective the other FFUs equipment ("PPE"), such as a = The foam should have a thermal resistance breathing apparatus, although (R-value) of at least 3.0 Fft2h/BTU
per inch chemical goggles, dust mask, and = The foam should be non-sagging and non-gloves are acceptable dripping (i.e., fire retardant) during a fire = The foam should not lend itself to = The foam should not corrode metal objects molding or fungus growth (ASTM such as screws, nails, electrical boxes, and C1338) the like = The foam should not contain a food source for insects or rodents = Air infiltration should be negligible (ASTM
= There should be a minimum shelf life E283-04) (spec 0.4 cfm/ sq ft) of the un-reacted constituents of 9 = Water vapor infiltration should be greater months. then 1 perm or 5.72x10-8 g/Pa-s-m2 = The foam should have low or no odor.

Colloid-forming, coagulatable polymer [0044] As discussed above, the foamable composition according to the present invention includes a coagulatable polymer or resin that forms a colloid when dispersed in a non-aqueous serum phase. As implied by the name, this polymer is in solid, particulate form and of sufficiently fine particle size to be colloidally dispersed in the serum. Such polymers are routinely prepared by suppliers for aqueous dispersions or latexes, and may even be called latex resins even when in a particulate or powder form. Suitable polymers may be prepared by any of the well known processes, including but not limited to suspension polymerization and emulsion polymerization as described in the literature, for example, Rodriguez, F., PRINCIPLES OF
POLYMER Sys ILMS, 2d Ed. McGraw Hill, 1982, pages 105-125, incorporated herein by reference. The polymers may and usually do include a "colloid surfactant" as part of their formulation, which enhances their formation of stable lattices in dispersions.
Suitable polymers are available from a wide variety of suppliers, including Dow Chemical, BASF, and others.

[0045] Non-limiting examples of suitable polymers for use in the inventive compositions include acetic acid ethenyl ester polymers; polyvinyl chloride (PVC);
polyvinylidene chloride;
acrylics; neoprene; styrene-butadiene rubber (SBR); nitrile rubbers (e.g., acrylonitrile-butadiene); polyisoprene rubbers; polychloroprene rubbers; polybutadiene rubbers; butyl rubbers; ethylene-propylene-diene monomer rubbers (EPDM); polypropylene-EPDM
elastomers;
ethylene-propylene rubbers; styrene-butadiene copolymers; styrene-isoprene copolymers;
styrene-butadiene-styrene rubbers; styrene-isoprene-styrene rubbers; styrene-ethylene-butylene-styrene rubbers; styrene-ethylene-propylene-styrene rubbers; polyisobutylene rubbers; ethylene vinyl acetate rubbers; silicone rubbers including, for example, polysiloxanes;
methacrylate rubbers; polyacrylate rubbers including, for example, copolymers of isooctyl acrylate and acrylic acid; polyesters; polyether esters; polyvinylidene chloride; polyvinyl ethers;
polyurethanes; and combinations thereof. These polymers and polymers like these undergo a process of "drying" or "coagulating" to form a polymeric film as is well known in the art.

[0046] The colloid-forming polymer(s) may be present in an amount from about 20 to about 65 percent by weight of the foamable composition, and in exemplary embodiments, in an amount from about 25 to about 50 percent by weight, or from about 25 to about 40 percent be weight. In two part dispersions, the colloid-forming polymer(s) may be present in an amount from about 40 to about 75 percent, or from about 50 to about 70 percent by weight of the dispersion in which it is contained.

[0047] The polymer is capable of coagulating upon itself to form a film. In some embodiments, the polymer may be a functionalized polymer, i.e. resins having reactive functional groups that additionally crosslink to enhance coagulation. Such functional groups may include, for example, carboxyl, hydroxyl, amino, epoxy and other moieties known to be reactive. Importantly, the functional groups may often interact with the crosslinking reactant system described below, and the degree to which the resin is functionalized may be important in defining the properties of the resultant foams. Too little crosslinking or too much crosslinking and the foams lose some of their elastomeric properties.
Non-aqueous serum phase [0048] The polymer, described above, is dispersed in a non-aqueous serum phase, a liquid and preferably a vaporizable or volatile liquid. By "volatile" is meant that the serum has a boiling point that ranges from about 0 F to about 80 F, more likely from about 15 F to about 60 F, so that it can be vaporized to a gas phase upon atmospheric application in a wide range of climates, possibly without applying further heat to cause the vaporization.
Boiling point is known to be dependent on both temperature and pressure, so that lower boiling serums can be kept from premature boiling by pressurization, if desired. Alternatively, somewhat higher boiling points may be used without pressurization if the serum is heated upon application. Both pressurization and heat may be employed. The gas phase generated in this manner becomes an integral part of the foam as it becomes entrained in pockets or cells bounded by the film of the coagulating polymer.

[0049] Ideally, the serum phase may be a typical blowing agent, provided they meet the "volatile" criteria. Suitable, non-limiting examples of blowing agents that may be used as the serum phase include C1 to C9 aliphatic hydrocarbons (e.g., methane, ethane, propane, n-butane, cyclopentane, isobutane, n-pentane, isopentane, and neopentane), C1 to C3 aliphatic alcohols (e.g., methanol, ethanol, n-propanol, and isopropanol), HFC blowing agents (e.g., 1,1,1,3,3-pentafluoropropane (HFC-245fa), 1,1,1,4,4,4 -hexafluorobutane (HFC-356mff), 1,1,1,3,3-pentafluorobutane (HFC-365mfc), 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1-difluoroethane (HFC-152a), 1,1,1,3,3,3-hexafluoropropane (HFC-236fa), 1,1,1,3,3-pentafluorobutane (HFC-365mfc)); and nitrogen. It is to be appreciated that any of the blowing agents for use in the foamable composition can be used singly or in any combination thereof.
Eliminating an acid/base blowing agent system utilizing sodium bicarbonate also eliminates sodium from the final foam. Sodium can be detrimental to the foam as it is hydrophilic in nature. The blowing agent may be present in an amount from about 10 to about 40 percent by weight of the composition, and in exemplary embodiments, in an amount from about 15 to about 30 percent by weight. In two part dispersions, the blowing agent may be present in an amount from about 25 to about 50 percent, or from about 30 to about 40 percent by weight of the dispersion in which it is contained.
Crosslinking reactant system [0050] The next component of the inventive foam composition is a crosslinking reactant system. This system may involve more than two reactants, but binary systems are simple and sufficient, so the embodiments described will include two reactants as members of a reactant pair. The reactant members contain backbones that may be solely hydrocarbon or hydrocarbon with heteroatoms; and the backbones generally contain at least 3 atoms, but may contain many more, and may be formed as monomers or as oligomers of repeating units. Spaced along these backbones, the first and second reactant members have at least two and preferably three or more reactive or functional groups that are capable of crosslinking at or about room temperature. The exact nature and composition of the backbone is not critical; it merely needs to provide covalent attachment points for the reactive functional groups, preferably with some spacing so as to provide rotational degrees of freedom about the bonds and avoid steric hindrance of adjacent reactive groups.

[0051] The reactive or functional crosslinking groups are provided in pairs, the first reactant generally containing the one member of the pair and the second reactant containing the other member of the pair. The members of the pair react to crosslink at or about room temperature and without the need for addition of significant heat or activation energy. For this purpose, heat added by an application device to vaporize a serum phase blowing agent is not considered significant heat. Consequently, the first and second reactants are isolated prior to use in an application of the foamable composition. The first and second reactants are isolated from one another in some embodiments by providing them in two separate and distinct dispersions, as is typical in the case of polyurethane and latex spray foams: an A-side and a B-side.
Alternatively, they may be isolated by encapsulation or protection of the reactive groups, which encapsulation or protection is removed during the application process. These mechanisms are described in more detail below.

[0052] Pairs of reactant members and their reactive functional groups suitable for the crosslinking reactant system include but are not limited to:
(a) a polyfunctional aziridine and a polyfunctional (carboxylic) acid;
(b) a polyfunctional (isocyanate) oligomer and a polyfunctional (hydroxyl) alcohol; and (c) a polyfunctional (amine) and a polyfunctional (epoxy) oligomer.

Polyfunctional in this context refers to at least two (difunctional), three (trifunctional) or higher level of reactive groups per backbone molecule. Three or more reactive groups per backbone molecule are considered polyfunctional or multifunctional. Each pair member of the crosslinking reactant system will have an "effective equivalent" number of functional groups that may be estimated theoretically and determined empirically. The "effective equivalent" number of functional groups is often less than the actual number due to the inevitable steric hindrance of some functional groups in larger molecules. In general, it is desirable to provide the first reactant and second reactant in equal "effective equivalents" i.e. in a 1:1 molar ratio considering moles of available or "effective" functional groups. However, this ratio is variable and may encompass a wider range, such as, for example, from 0.5:1 to 2:1 to provide the optimum crosslinking in the final foam products. When functionalized polymers are employed, the ratio may ideally be adjusted to add more equivalents of whichever reactant tends to react with functional groups of the polymer.

[0053] Polyfunctional aziridines are most commonly found in di- and tri-functional compounds. Suitable examples include XAMA('-7 and XAMA('-2, tri-functional aziridines available from Bayer Corporation; PZ-33, an ethylene imine-based tri-functional polyaziridine available from PolyAziridine, LLC; Crosslinker CX-100, a polyfunctional aziridine available from DSM NeoResins; and XC-103, a trifunctional aziridine available from Zealchem. Because these aziridines are highly reactive with acidic protons, it is desirable to ensure that no water or other ionizable species that produce free protons are available in dispersions with the aziridines.
These polyfunctional aziridines may be used singly or in combination, and may be present in an amount from about 2 to about 25 percent by weight of the dry foam composition, preferably in an amount from about 3 to about 10 percent by weight. In two part dispersions, the polyfunctional aziridines may be present in an amount from about 10 to about 25 percent, or from about 15 to about 18 percent by weight of the dispersion in which it is contained.

[0054] In exemplary embodiments, the polyfunctional acid is a dry acid powder without chemically bound water. Non-exclusive examples of polyfunctional acids include, but are not limited to, polyacrylic acid, citric acid, oxalic acid, tartaric acid, succinic acid, fumaric acid, adipic acid, maleic acid, malonic acid, glutaric acid, phthalic acid, metaphosphoric acid, or salts that are convertible into an acid that is an alkali metal salt of citric acid, tartaric acid, succinic acid, fumaric acid, adipic acid, maleic acid, oxalic acid, malonic acid, glutaric acid, phthalic acid, metaphosphoric acid, or a mixture thereof. Examples of salts which are convertible into acids include, but are not limited to, aluminum sulfate, calcium phosphate, alum, a double salt of an alum, potassium aluminum sulfate, sodium dihydrogen phosphate, potassium citrate, sodium maleate, potassium tartrate, sodium fumarate, sulfonates, and phosphates. The polyfunctional acid may be monomeric (as are many described above) or polymeric in nature.
Urethane oligomers have been prepared having pendant functional carboxyl groups. In exemplary embodiments, the acid is a polyacrylic acid. These polyfunctional acids may be used singly or in combination, and may be present in an amount from about 1.0 to about 10 percent by weight of the dry foam composition, and in exemplary embodiments, in an amount from about 3.0 to about 7.0 percent by weight. In two part dispersions, the multifunctional acid may be present in an amount from about 2 to about 10 percent, or from about 4 to about 6 percent by weight of the dispersion in which it is contained.

[0055] In some embodiments, the multifunctional acid may be a secondary emulsion that is added to the composition separately. For example, if the multifunctional acid is not miscible in the non-aqueous serum phase, then the acid may be introduced into the foamable composition as a stable emulsion (e.g. water in oil) within the serum phase. The multifunctional acid may be placed into an emulsion with the assistance of a surfactant, such as the surfactants described herein.

[0056] Another pair of reactants that can form scaffolding is: polyfunctional (isocyanate) oligomer and a polyfunctional (hydroxyl) alcohol or polyols. These reactants are similar to those found in typical polyurethane foams and are well known in the art to crosslink at or about room temperature. See, e.g. Szycher's Handbook of Polyurethanes, CRC Press, Boca Raton, FL 1999, pp. 3-1 to 3-39 in particular, which are incorporated herein by reference.

[0057] However, there are two key distinctions in the present invention.
First, a reduced amount of isocyanate is required since the purpose is merely to create a crosslinked scaffold structure, not form the complete resin film. Second, the isocyanates are pre-polymerized to form oligomers to minimize the toxicity of isocyanate groups. Prepolymers combine multiple isocyanate molecules (e.g. from 2 to about 5 or more) and in this way the NCO
content can be reduced from about 16 -30% by weight (as in monomers) to about 1 to 14% by partial polymerization. This NCO content range still affords suitable reactivity with the hydroxyl groups of polyols to generate a three dimensional scaffold and has suitable viscosity required for flowability. Useful isocyanate prepolymers include, e.g. Dow EchelonTM pre polymers, Bayer BaytecTM and/or Huntsman pre-polymers.

[0058] Polyols useful as the second reactant member of the isocyanate-polyol pair are discussed in Ionescu, M., Chemistry and Technology of Polyols for Polyurethane, Smithers Rapra Press, 2008, incorporated herein by reference. Polyols used to produce polyurethanes are typically in the molecular weight range of 400 to 5000 Daltons and may include the classes of polyethers and polyesters. In general, low molecular weight polyols create hard plastics while high molecular weight polyols create flexible elastomers. Some important illustrative polyols include glycerine, poly(propylene oxide) glycol, castor oil, poly(ethylene adipate), polycaprolactone, polytetra methylene ether glycol (PTMEG), polycarbonate and VoranolTM (a polyether triol available from Dow Chemical).

[0059] Some examples of isocyanate prepolymers available in the market and corresponding polyols are given in the table below:

Supplier Product Polyol base Iso type % NCO
Bayer Baytec ME-050 PTMEG MDI* 5.9 Bayer Baytec ME-120 PTMEG MDI 12 Bayer Baytec MP-080 Polyether MDI 8.0 Bayer Baytec MP-090 Polyether MDI 9.0 Bayer Baytec MS-041 Polyester MDI 4.1 Bayer Baytec MP-090 Polyester MDI 9.0 Dow Echelon MP-100 MDI 10.2 Dow Echelon MP-104 MDI 16 Dow Echelon MC-400 MDI 10.2 *MDI = methylene-diphenyl-di-isocyanate [0060] Another pair of reactants that can form a crosslinked, "scaffold-like" structure is:
polyfunctional (amine) and a polyfunctional (epoxy) oligomer. See, eg.
Rozenberg, B.A., Kinetics, thermodynamics and mechanism of reactions of epoxy oligomers with amines, in ADVANCES IN POLYMER SCIENCE, 1986, Volume 75/1986; pp 113-165, incorporated herein by reference. The most common epoxy used in industry is diglycidyl ether of bisphenol A
(DGEBA). This epoxy is sold by Dow Chemical under the trade name DER 331. Some common amine reactants for epoxy would be as follows:
Supplier Chemical Dow Diethyl triamine (DETA) Dow Triethylene triamine (TETA) Dow Amino ethyl piperazine (AEP) Dow Polyethylene polyamine Plasticizer [0061] According to some embodiments of the invention, the foamable composition may include a plasticizer. Plasticizers are known to lower the glass transition temperature (Tg) of polymers and may be used to facilitate softening of the polymer colloid particles, leading to coagulation to the film. Useful plasticizers have been found in the di/tri-carboxylic ester class and the benzoate ester class, although other classes may be suitable. Examples of suitable plasticizers include butyl benzoate, Benzoflex 2088 (a benzoate ester plasticizer available from Genovique Specialties), Benzoflex LA-705 (a benzoate ester plasticizer available from Genovique Specialties), Citroflex 2 (a triethyl citrate available from Vertellus Specialties), and Citroflex 4 (a tributyl citrate available from Vertellus Specialties). In exemplary embodiments, the plasticizer is a benzoate ester or a citric acid ester.

[0062] In embodiments employing separate A-side and B-side dispersions, the plasticizer may be additionally useful as a vehicle or medium for B-side dispersions, thus diluting one of the crosslinking reactants. For example, diluting a polyfunctional aziridine provides several advantages. First, the concentration of polyfunctional aziridine is lowered, reducing health risks to those in contact with it. Polyfunctional aziridine contains about 0.001% of ethyleneimine, which is a very reactive moiety, and in theory, will react with the very small level of acid impurities or water content that may be present in other components of the composition. Second, the viscosity of the B-side is reduced when the polyfunctional crosslinking reactant is diluted with the plasticizer. As a result, the components of the B-side can be better mixed with the A-side to form a more homogeneous mixture. Finally, the plasticizer adds volume to the B-side, allowing the two parts of the foam composition to be delivered in ratios that more closely approach 1:1, and thus they can be delivered with known spray equipment, thereby negating the need for any specialized equipment.

[0063] The plasticizer, when used, is generally present in an amount from about 2 to about 20 percent by weight of the dry foam composition, and in exemplary embodiments, in an amount from about 2 to about 15 percent by weight. In two part dispersions, the plasticizer may be present in an amount from about 10 to about 80 percent, or from about 20 to about 60 percent by weight of the dispersion in which it is contained.

[0064] Additionally, the presence of the plasticizer permits for the inclusion of other solid materials that may add functionality and/or cost savings to the final foamed product. For instance, coagulation agents, fillers (e.g., calcium carbonate and wollastonite fibers), nucleating agents (e.g., talc), and/or foaming agents (e.g., sodium bicarbonate) can be included in the B-side of the foamable composition. The inclusion of fillers such as wollastonite fibers helps with the stability of the cell structure after the cells have been formed. It is to be appreciated that when the plasticizer and other components in the B-side do not contain any acidic protons, the B-side is stable for extended periods of time, such as up to at least six months or more.
Surfactants, colloid and film [0065] As noted above, the solid colloid-forming polymer may optionally contain a "colloid surfactant" that interfaces between polymer and serum to help stabilize the polymer lattice in dispersions. In some cases, it may be desirable to add additional surfactant and/or a secondary "film surfactant" to the foamable composition. The film surfactant, when used, may be the same or different since it serves a different purpose. Instead of stabilizing the polymer lattice, the film surfactant interfaces between polymer and the entrained gas phase and is used to stabilize the film formation during the foaming process and to provide a high surface activity for the nucleation and stabilization of the foam cells. Useful surfactants for lattice and/or film formation include cationic, anionic, amphoteric and nonionic surfactants such as, for example, carboxylate soaps such as oleates, ricinoleates, castor oil soaps and rosinates, quaternary ammonium soaps and betaines, amines and proteins, as well as alkyl sulphates, polyether sulphonate (e.g., Triton X200K available from Cognis), octylphenol ethoxylate (e.g., Triton X705 available from Cognis), disodium N-octadecyl sulfosuccinamate (e.g., Aerosol 18P
available from Cytec), octylphenol polyethoxylates (e.g., Triton X110 available from Cognis), alpha olefin sulfonate, sodium lauryl sulfates (e.g., Stanfax 234 and Stanfax 234LCP from Para-Chemicals), ammonium laureth sulfates (e.g., Stanfax 1012 and Stanfax 969(3) from Para-Chemicals), ammonium lauryl ether sulfates (e.g., Stanfax 1045(2) from Para-Chemicals), sodium laureth sulfates (e.g., Stanfax 1022(2) and Stanfax (1023(3) from Para-Chemicals), sodium sulfosuccinimate (e.g., Stanfax 318 from Para-Chemicals), and aliphatic ethoxylate nonionic surfactants (e.g., ABEX available from Rhodia). The choice of a particular surfactant may be guided by ionic preference, HLB and the specific properties of the adjoining medium (serum or gas phase), but remains largely an empirical choice. The surfactant may be present in the foamable composition in an amount from about 0.05 to about 2.0 percent by weight of the A-side composition, and in exemplary embodiments, in an amount from about 0.4 to about 1.0 percent by weight.
Other Optional Ingredients [0066] As noted, the foamable composition may contain other optional ingredients, in either or both of an A-side and B-side when separate dispersions are used.
Such optional ingredients may include a nucleating agent, coagulation agents, foam promoters, opacifiers, accelerators, foam stabilizers, dyes (e.g., diazo or benzimidazolone family of organic dyes), color indicators, gelling agents, flame retardants, biocides, fungicides, algaecides, fillers (aluminum tri-hydroxide (ATH)), and/or blowing agents. It is to be appreciated that a material will often serve more than one of the aforementioned functions, as may be evident to one skilled in the art, even though the material may be primarily discussed only under one functional heading herein.
The additives are desirably chosen and used in a way such that the additives do not interfere with the mixing of the ingredients, the cure of the reactive mixture, the foaming of the composition, or the final properties of the foam. Other optional additives can be between 0 and 10% of the final formulation.

[0067] Suitable, non-limiting examples of nucleating agents that may be used in the spray foam of the present invention are talc, precipitated calcium carbonate, and silica. The nucleating agent may be present in an amount from about 1.0 to about 10.0 percent by weight of the dry foam composition, and in exemplary embodiments, in an amount from about 1.0 to about 5.0 percent by weight.

[0068] Coagulation agents facilitate the coagulation process to help establish the film, generally from 0 to 3% by weight. Suitable, non-limiting examples of coagulation agents that may be used in the spray foam of the present invention are diethylene glycol butyl ether, dipropylene glycol n-butyl ether, isopropyl alcohol, and ethyl alcohol.

[0069] It is to be appreciated that the inventive foam and composition are desirably free of water. However, small amounts (e.g., 2-3%) of water may be brought into the system, such as though added components, as is discussed in detail below. However, the water is in such a small amount that it does not disrupt the foam process or create other problems heretofore associated with the inclusion or presence of water in foamable compositions. The water-free or substantially water-free foam composition as recited herein enables the foam to be sprayed to a greater thickness than water-containing foams. For instance, in known latex foams, the weight of the water prevents the foam from being able to support itself. Thus, the foam, after being sprayed, will slide down a vertical surface under its own weight. Also, the lack of water in the inventive foams permits the foam to be closed celled with a relatively low density. In some exemplary embodiments, the density of the foam may be between about 0.5 and about 20 pounds per cubic foot, or from about 15 to about 18 pounds per cubic foot. In addition, the water present in known latex foams can freeze, thereby destroying the structural integrity of the foam. Further, the lack of water in the inventive foam composition permits the foam to be sprayed at low temperatures, including below-freezing temperatures.

[0070] Much has already been described relating to the use of two-part foamable compositions as a means to isolate the first and second reactants of the crosslinking reactant system. But exemplary isolated dispersions with multiple and optional ingredients are set forth in the examples and in the table below.

A-side B-side suggested Coagulatable, colloid-forming polymer Polyfunctional aziridine Poly(carboxylic) acid Plasticizer serum Non-aqueous blowing agent serum Film surfactant optional Wollastonite Additional resin Talc or calcium carbonate Coagulation agent In use, the A side is mixed with the B side in a A:B ratio ranging from about 1:1 to about 5:1 to form a foam product. The relative weight ratio depends in part on the nature of the polyfunctional crosslinking reactants, (i.e. how much function per weight) and the desired end-use application.

[0071] Alternatively, a one-part foamable composition may be prepared using encapsulation as a means to isolate the first and second reactants of the crosslinking reactant system, as well as any additional components that would prematurely react, such as acidic protons in the case of aziridines or functional groups if present on a polymer resin. In general, the reactive components are separated or isolated by means of encapsulation in a protective shell or coating as described in more detail in US Patent Publication 2008/0161430, incorporated herein by reference. The protective shell may be a wax or gelatin that can be melted at the time of the application of the foam. Alternatively, the encapsulating shell may be formed of a brittle polymer (such as a melamine formaldehyde polymer) or an acrylic that can be broken or sheared at the time of the application of the foam. Optionally, the encapsulating material may be a low melting, semi-crystalline, super-cooled polymer. Only one member of any reactant pair need be encapsulate and, with judicious choices, a minimum number of reagents may need encapsulation.
The reactants are released at time of application by means of heat, shear, sonication, photoactivation or other technique to disrupt the encapsulating shell.

Methods and Process [0072] To form a two-part spray foam of the present invention, the components of the A-side and the components of the B-side may be delivered through separate lines into a spray device, such as an impingement-type spray gun. Depending on choice of the serum phase, the gun may be heated to a temperature above the boiling point of the blowing agent. It is to be appreciated that the heat being supplied to the mixture may be derived from external sources such as built-in heaters, a heated hose, or a heated gun; or from internal sources, such as heat of exothermic reactions. The two components are pumped through small orifices at high pressure to form streams of the individual components of the A-side and the B-side. The streams of the first and second components intersect and mix with each other and heat up within the gun.

[0073] Upon contact, the first and second reactants of the crosslinking reactant system quickly begin to crosslink, forming a three dimensional, covalently crosslinked structure believed to resemble a scaffold or skeleton. If a functionalized polymer is used, reactions may occur between it and the first and /or second reactants as well. This scaffold-like structure supports the foam while the polymer is coagulating and hardening. The previously fluid/viscous foam material is substantially immobilized by the internal scaffold-structure, which prevents the foam from collapsing before it coagulates. It is hypothesized that the use of a multifunctional acid advantageously provides for a more flexible backbone in the polymeric structure.

[0074] Because the components are under pressure inside the gun, the blowing agent does not vaporize. However, as the mixture exits the gun and enters into atmospheric pressure, the blowing agent begins to vaporize just as the scaffold is forming. As the continuous serum phase vaporizes, the lattice particles necessarily become more concentrated until a point at which they destabilize, coagulate and form a film on the growing crosslinked structure. The very action of the serum phase turning to vapor forces the lattice particles together, while at the same time, it supplies the gas phase for entrainment in the polymer to from the foam.

[0075] It is to be appreciated that the crosslinking is important for capturing the gas bubbles in their original, fine structure before they can coalesce and escape the foam. A fine foam structure is more desirable and more beneficial than a coarse foam structure in order to achieve a high structural, thermal, and air sealing performance. Additionally, if present, the functional groups on the colloid-forming polymer quickly crosslink and build strength in the foam, and permit the foam to withstand the force of gravity when it is placed, for example, in a vertical wall cavity during application. As noted earlier, the degree of crosslinking between a functionalized resin and members of the crosslinking reactant system may also have an impact on the elastomeric and other properties of the foam.

[0076] The final foamed product becomes cured to the touch within about 1-3 minutes after application, typically within about 2 minutes; and hardens within about 1 to 6 minutes. In foams intended for use as insulating materials, the resulting resistance to heat transfer, or R-value, is desirably from about 3.5 to about 8 per inch. In certain uses, the foamed product has an integral skin that restricts the passage of air but permits the passage of water vapor.

[0077] In use, the inventive foams may be sprayed into a closed cavity where it expands to seal any open spaces. In another embodiment, the foams of the present invention may be used to seal the insulative cavities of a building such as a house and minimize or eliminate air flow into the insulative cavities and effectively seal the building. The foams of the present invention may also be used to insulate buildings such as homes from temperature fluctuations outside of the building's envelope. Additionally, the foams of the present invention may serve as a sealant to air infiltration by filling cracks and/or crevices in a building's roof or walls, around doors, windows, electric boxes, and the like. The foam may also be applied to seal holes in walls and floors. The foams may serve both as a conductive and a convective thermal barrier. In exemplary embodiments, the application of the foam is a continuous spray process.

[0078] The inventive foam can also be used in applications where extruded polystyrene foam forms the envelope of a building. Although polystyrene foams are good insulators, they have a tendency to buckle and create gaps and/or crevices. Similarly, when a fibrous board is used as the sheathing, gaps and crevices naturally occur, such as at the interfaces between the sheathing and framing due to the natural warping and curvature of fibrous products. The inventive foams may be sprayed into these crevices and gaps as a sealant to reduce or eliminate air infiltration into the insulative cavity.

[0079] Additionally, the inventive foams may be applied to the faces of the studs (or the face of the framing of the building) to obtain a superior seal against air infiltration. In particular, the inventive foam is sprayed or otherwise applied to the face of the studs as described above and drywall is attached to the surface of the studs in any known manner.
Desirably, the foam is sprayed onto the stud faces prior to the insertion of the insulation into the building cavities. It is to be understood that the foam may be sprayed to the faces of the studs with or without applying the foam around the interior boundary of the insulative cavities. The elastomeric foam acts as a gasket seal between the stud face and the drywall. In addition, the foam assists in leveling and smoothing the stud surface to which the drywall will be attached.

[0080] The spray foam composition of the present invention has several benefits. One important benefit of the inventive foam composition is that the foam may be applied in cold conditions, including temperatures approaching about 20 F, without adversely affecting the nature of the foam. Moreover, the spray foam of the present invention contains no water or, if water is present (such as, for example, in an additive), the water is present in only a small amount. The lack of water (or small amount of water) in the spray foam means that water not is present in the foam in an amount such that it would freeze at low temperature and disrupt the quality of the foam. A further benefit resulting from the lack of water in the spray foam of the present invention is that the blowing agent can vaporize quickly and leave no residue, like water, which diffuses very slowly over time.

[0081] Another advantage of the foams of the present invention is the safe installation of the foam into cavities. Because the foams do not release any harmful vapors into the air when applied or sprayed, the inventive foams reduce the threat of harm to individuals working with or located near the foam. In addition, the application of the foams is more amenable to the installer as he/she will not need to wear a special breathing apparatus during installation.

[0082] Another advantage of the inventive foams is that it can be used in the renovation market, as well as in houses that are occupied by persons and/or animals (e.g.
renovation market). Existing spray polyurethane foams cannot be used in these applications because of the generation of high amounts of free isocyanate monomers that could adversely affect the occupants of the dwelling. As discussed above, exposure of isocyanate monomers may cause irritation to the nose, throat, and lungs, difficulty in breathing, skin irritation and/or blistering, and a sensitization of the airways.

[0083] It is also an advantage of the spray foam that, unlike known spray polyurethane foams, the foams of the present invention do not contain isocyanate.
Therefore, no MDI
monomers are present in the inventive foams. Because the inventive foam does not contain isocyanate, no harmful chemicals are emitted during installation of the foams.

[0084] Having generally described this invention, a further understanding can be obtained by reference to certain specific examples illustrated below which are provided for purposes of illustration only and are not intended to be all inclusive or limiting unless otherwise specified.
EXAMPLES

[0085] Example 1. The following example illustrates how to make some exemplary two-part embodiments of the inventive foam. Table 1 sets forth a list of components, given as weight percent present in the A-side and B-side respectively of five (A-E) two-part foam compositions.
Table 1- Components A B C D E
SIDE A Pct. Pct. Pct. Pct. Pct.
Solid Polymer DLP - 2141 Dow Chemical 65 65 DLP - 2001 Dow Chemical 65 65 DLP - 211 Dow Chemical 65 Surfactant A B C D E
Triton GR5M Cognis 1 1 1 Stanfax 234 Para-Chemicals 1 Serum Phase/ Blowing Agent HFC-245(fa) Honeywell 19 19 19 13 Water --- 5 5 5 5 Polyfunctional First Reactant Aquaset 1676 (poly acid) Dow Chemical 5 5 5 Glycerine (poly hydroxyl) --- 5 5 5 Voranol 230-238 Polyether Dow Chemical 14 triol (238 OH number) Catalyst PMDETA (N,N,N',N',N"-PENTAMETHYLDIETHYLENETRIAMINE)* 1 DMCHA (N,N-Dimethylcyclohexylamine)** 1 A-side total (%) 100 100 100 100 SIDE B A B C D
E
Serum/ Plasticizer Pct. Pct. Pct.
Pct. Pct.
Benzoflex 2088 Genovique 61 10 Specialties Citroflex 4 VertellusC) 61 Specialties Citroflex 2 VertellusC) 61 Specialties Polyfunctional Second Reactant PZ-33 (poly Aziridine) PolyAziridine, 17 17 17 PLLC
Echelon MP-100 Dow Chemical 90 Polyurethane Prepolymer (10.2% NCO) Baytec MP-90 isocyanate Bayer Chemical terminated polyether prepolymer (9 % NCO) Filler Calcium Carbonate 10.7 10.7 10.7 Thickening Agent A
Thixatrol Max Elementis 1.3 1.3 1.3 Specialties Vansil HR 1500 RT Vanderbilt 10 10 10 Co, Inc.
B-side total (%) 100 100 100 100 100 Ratio A:B 4:1 4:1 4:1 1:1 1:1 * Blowing catalyst ** Gelling catalyst [0086] The A-side and the B-side of each formulation (A-E) are mixed together in a weight ratio (A:B) as indicated in the table (either 4:1 or 1:1) to form a foam product.

[0087] Example 2. The following example illustrates how varying the degree of crosslinking between a functionalized resin and the crosslinking reactant system impacts the elastomeric properties of the foam.

[0088] [insert new data]

[0089] The invention of this application has been described above both generically and with regard to specific embodiments, although a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure. The invention is not otherwise limited, except for the recitation of the claims set forth below.

Claims (24)

1. A non-aqueous foamable composition comprising:
a solid, coagulatable polymer colloidally dispersed in a non-aqueous, vaporizable serum phase, optionally with a surfactant; and a crosslinking reactant system comprising at least first and second members of a reactant pair, each member having multiple reactive groups characterized such that, upon combination at or about room temperature, the reactive groups of one member crosslink with the reactive groups of at least the other member to form a polymeric crosslinked structure upon which the polymer forms a film as it coagulates, wherein the first and second members of the reactant pair are isolated from one another until combination.

2. The non-aqueous foamable composition of claim 1, wherein the first and second members of the reactant pair are selected from the pairs:
(a) a polyfunctional aziridine and a poly(carboxylic) acid;
(b) a poly(isocyanate) oligomer and a poly(hydroxyl) alcohol; and (c) a poly(amine) and a poly(epoxy) oligomer.

3. The non-aqueous foamable composition of claim 2, wherein the first and second members of the reactant pair are a polyfunctional aziridine and a poly(carboxylic) acid.

4. The non-aqueous foamable composition of claim 3, wherein said poly(carboxylic) acid is a dry acid powder without chemically bound water.

5. The non-aqueous foamable composition of claim 2, wherein one member of the crosslinking reactant system is in the form of a secondary emulsion added separately to said non-aqueous serum phase.

6. The non-aqueous foamable composition of claim 1, further comprising a plasticizer. 32

7. The non-aqueous foamable composition of claim 6, wherein said plasticizer is selected from a benzoate ester, triethyl citrate, a tributyl citrate, polyethylene glycol, an octylphenoxypolyethoxyethanol, butyl benzoate and combinations thereof.

8. The non-aqueous foamable composition of claim 6, wherein the members of the reactant pair are isolated in separate dispersions, one member being dispersed in the non-aqueous, vaporizable serum phase along with the coagulatable polymer (A-side), and the other reactant member being dispersed in the plasticizer (B-side).

9. The non-aqueous foamable composition of claim 1, wherein the vaporizable non-aqueous serum phase consists essentially of a volatile blowing agent

10. The non-aqueous foamable composition of claim 8, wherein at least one of the dispersions further comprises at least one member selected from a surfactant, a filler, a nucleating agent, a coagulation agent, and a non-reactive resin.

11. A foamed product comprising:
a polymeric film coagulated on the polymeric crosslinked structure formed by the reaction of at least first and second reactant members of the foamable composition of claim 1, the film entraining a gas generated by vaporization of the non-aqueous serum phase.

12. The foamed product of claim 11, wherein the first and second members of the reactant pair are selected from the pairs:
(a) a polyfunctional aziridine and a poly(carboxylic) acid;
(b) a poly(isocyanate) oligomer and a poly(hydroxyl) alcohol; and (c) a poly(amine) and a poly(epoxy) oligomer.

13. The foamed product of claim 12, wherein the first and second members of the reactant pair are a polyfunctional aziridine and a poly(carboxylic) acid.

14. A foamed product comprising:
a polymeric film coagulated on the polymeric crosslinked structure formed by the reaction of at least first and second reactant members of the foamable composition of claim 8, the film entraining a gas generated by vaporization of the non-aqueous serum phase.

15. The foamed product of claim 14, wherein said plasticizer is selected from a benzoate ester, triethyl citrate, a tributyl citrate, polyethylene glycol, an octylphenoxypolyethoxyethanol, butyl benzoate and combinations thereof.

16. A method of forming a foam comprising:
combining (a) a solid, coagulatable polymer colloidally dispersed in a non-aqueous, vaporizable serum phase, optionally with a surfactant, with (b) at least first and second members of a reactant pair of a crosslinking reactant system, each member having multiple reactive groups characterized such that, upon combination at or about room temperature, the reactive groups of one member crosslink with the reactive groups of at least the other member to form a polymeric crosslinked structure, to form (c) a reaction mixture;
applying said reaction mixture to a desired location; and destabilizing the lattice of the colloidal dispersion, whereby the coagulatable polymer begins to coagulate and form a film on the crosslinked structure while said non-aqueous serum phase vaporizes to form a gas that is entrained by the polymeric film.

17. The method of claim 16, wherein said non-aqueous serum phase vaporizes to concentrate the colloid and destabilize the lattice of the colloidal dispersion.

18. The method of claim 17, wherein said non-aqueous serum phase is selected to have a boiling point such that it vaporizes at ambient application temperature and atmospheric pressure; and further comprising pressurizing said colloidal dispersion prior to application to avoid premature vaporization.

19. The method of claim 17, further comprising heating said reaction mixture to a temperature above the boiling point of said non-aqueous serum phase to vaporize said non-aqueous serum phase. 34

20. The method of claim 16, wherein the step of combining the solid, coagulatable polymer with the members of a crosslinking reactant system, comprises mixing an A-side dispersion with a B-side dispersion, wherein said A-side dispersion contains the colloidally dispersed coagulatable polymer and one member of the reactant pair dispersed in a non-aqueous serum phase, and the B-side dispersion contains the other member of the reactant pair dispersed in a plasticizer.

21. The method of claim 16, wherein said reaction mixture is applied at a temperature near or below freezing.

22. A two-part non-aqueous foamable composition for forming a foam comprising:

a first component including:
a lattice phase formed of at least one dry, coagulatable polymer in a liquid blowing agent; a multifunctional acid; and a surfactant; and a second component including:
a polyfunctional aziridine crosslinking agent that crosslinks at or about room temperature; and a plasticizer, wherein said plasticizer has no acidic protons to react with said polyfunctional aziridine crosslinking agent.

23. The two-part non-aqueous foamable composition of claim 22, wherein said multifunctional acid is a dry acid powder without chemically bound water.

24. A foamed product comprising the reaction product of the first and second components of claim 22.