MXPA97009552A - Use of foam materials derived from internal high-phase emulsions for aislamie - Google Patents

Abstract

The invention relates to the use of polymeric foam materials for insulation. These polymeric foams are prepared by the polymerization of certain water-in-oil emulsions having a ratio of the water phase to the relatively high oil phase, commonly known in the art as "HIPE". The HIPE-derived foam materials used in the present invention comprise a polymeric foam structure of interconnected open cells, generally hydrophobic, flexible, semi-flexible or rigid, non-ionic. These foam structures have: A) a specific surface area per volume of foam of at least about 0.01 m / cm 2, B) a density of less than about 0.05 g / cm 2, and C) a glass transition temperature (T g) between about -20øy and 90øC. The foams can be used as thermal, acoustic and / or mechanical insulation materials. In a preferred embodiment, the foams used can be prepared, packaged and shipped in a compressed, high density state, and will return upon activation (e.g., by heat) to the original density of the foam.

Description

USE OF FOAM MATERIALS DERIVED FROM EMULSIONS OF HIGH INTERNAL PHASE FOR INSULATION FIELD OF THE INVENTION This application relates to the use of polymeric, open cell, microporous foam materials. This application particularly relates to the use of foam materials made of high internal phase emulsions.

BACKGROUND OF THE INVENTION The development of efficient and effective insulating materials has been the subject of substantial commercial interest. This is particularly true for materials that are thermal insulators, for example, that reduce the rate of heat lost (or gained) from any device, construction or container. Foams are widely used as insulators. References describing such uses and properties of the foams include Oertel, G. "Polyurethane Handbook" Hanser Publishers, Munich, 1985, and Gibson, L.J .; Ashby, M. F. "Structures and Solid Cellular Properties" Pergamon Press, Oxford, 1988. The term "insulator" refers to any material that reduces the transfer of energy from one location to another. Such energy may be included that of the heat, acoustic and / or mechanical types. Thermal insulation is of particular importance and is related to the thermal conductivity of the insulating medium. The "perfect" insulator is a vacuum. However, the development and maintenance of an evacuated space around the area to be isolated can be impractical, particularly for large volumes. The structural integrity required to withstand the atmospheric pressure acting on a vacuum vessel can be a principle. A common insulating medium is a foam or cellular material that has porous regions surrounded by a solid that provides integrity. The function of the foam as an insulator is to trap the air and reduce the thermal conductivity of the types described above. The foams are generally characterized by the size of the pores or cells within the structure, as well as by their density, which approximates the ratio of open to solid structure within the foam. The thermal conductivity of any foam depends on four characteristics: 1. Convection through the pores; 2. Driving through gas; 3. Driving through the polymer; and 4. Thermal radiation through cell walls and through cell voids. Convection via the movement of a gas through the pores of an insulating medium decreases with the cell size downward to approximately 4 mm, below which it becomes insignificant. The convention is suppressed through the pores in cells smaller than 10 mm. Most foams have much smaller cells than the scale in mm. Gas conduction can typically account for as much as two thirds of the thermal conduction of the system. For this reason, foams filled with low conductivity gases may be preferred, although the gas will typically exchange with the atmosphere over time. Driving through solid polymer with low density foams is negligible.

Thermal radiation can account for a quarter to a third of the thermal conductivity in a foam. (See Glicksman, LR, Marge, AJ Cell Plastics 1992, 28, 571, and DeVos, R., Rosbotham, D., Deschaght, J. Ibid 1994, 30, 302.) Radiant heat transfer is highly dependent on size of foam cell, and decreases with cell size (which would preferably be = 100 μm). Kodama et al. { ibid, 1995, 31, 24) reported improvements in the k-factor (a measure of the thermal insulation capacity) of a series of polyurethane foams ("PUF") while decreasing the average cell size from 350 μm to 200 μm. μm at a density of 0.052 g / cm3. Doerge reports that foams with densities of less than 0.037 g / cm3, approximately, showed increases in thermal conductivity attributable to the increase in cell size that typically occurs at these lower densities (Doerge, HP ibid, 1992, 28, 115), due in part to the increased transparency of cell walls and rupture of the cell wall (allowing rapid diffusion of the low conductivity gaseous filler). The best rigid insulating foams are low density foams (eg 0.03 to 0.07 g / cm3 for closed cell PUF) that have the smallest cells possibly filled with a gas that has a low coefficient of thermal conductivity (or not at all gas). In this way, it would be desirable to produce foams having both low density and very small cells, for example 100 μm. These foams apparently can not be produced by foam blowing procedures of the state of the art. The historical approach in the manufacture of insulating foams for the apparatus industry (for example, refrigerators, water heaters, etc.) has been the use of chlorofluorocarbons (CFCs) as physical agents for inflation, especially for foams based on starting materials of polyurethane and polyisocyanate. The association reported between the CFC and the depletion of the ozone layer has severely reduced its production and increased the need for materials and / or alternative methods for the production of foams. However, alternate insufflation agents such as carbon dioxide or pentane develop insulating foams of lower efficiency relative to those made with CFC. This results from the difficulty in achieving the same perfection of microstructure and possible densities with foams insufflated with CFC.

See for example Moore, S.E. J. Cell. Plastics 1994, 30, 494 and U.S. Patent No. 5,034,424 (Wenning et al.) July 23, 1991. See also Oertel, page 273; Gibson and Ashby, Chapter 7, page 201. Polyurethane foams are perhaps the most widely used type in such applications. The chemistry used in the processing has certain disadvantages including poor photostability (see Valentine, C; Craig, TA; Hager, SLJ Cell, Plastics 1993, 29, 569), the unavoidable existence of undesirable chemical residues in the foams (see Patent of United States 4,211, 847 to Kehr et al., issued July 8, 1980, and United States Patent 4,439,553 to Guthrie et al., issued March 27, 1984, which describe efforts to minimize this waste), and the production of noxious fumes developed during combustion, due to the presence of nitrogen atoms within the composition (see Hartzell, GEJ Cell Plastics, 1992, 28, 330). This can be particularly problematic in accidents involving public transportation such as boats, cars, trains or airplanes, which can catch fire. Injuries and deaths can result only from the inhalation of these harmful gases. See Gibson and Ashby Chapter 8, page 212. This can also be a principle when the foams are discarded in a stream of waste that is going to be incinerated. The construction insulation industry has extensively used rigid foamed polystyrene panels (in addition to insulating with pieces of glass and blown cellulose). Polystyrene foam panels are useful in that they are rigid and can be nailed during construction, are hydrophobic to provide moisture resistance (which would otherwise decrease the insulation value), and are relatively inexpensive. See Oertel page 277. This material is also widely used in glasses for beverages and food containers. The cell size of these materials are typically in the range of 300 to 500 μm. The smaller cell polystyrene foams have been prepared using the Thermally Induced Phase Separation Process (TIPS) described in Chemtech 1991, 290, and in U.S. Patent 5,128,382 (Ellíott et al.) Issued July 7, 1992 , incorporated here by reference. An important principle in the production of commercially attractive polymeric insulation foams for use as insulators is the economical one. The economy of the foams depends on the amount and cost of the monomers used, as well as the cost of conversion of the monomers to a usable polymer foam. The effort to reduce the cost of such insulating foams, especially in terms of reducing the total amount of monomer used, can make it very difficult to achieve the desired insulation and mechanical properties. Accordingly, it would be desirable to be able to make a polymeric, open-cell, insulating foam material that: (1) has adequate stiffness or flexibility in accordance with the requirements of use; (2) can be made with relatively small cell sizes to limit the thermal conductivity contributed by radiation; (3) can be made without chlorofluorocarbons or other gases that may induce undesired environmental problems; (4) does not contain chemically nitrogen bonds in the structure that, when combustion occurs, can release toxic gases; and (5) can be manufactured economically without sacrificing the desired insulating and mechanical properties to an unacceptable degree.

BRIEF DESCRIPTION OF THE INVENTION The present invention relates to the use of polymeric foam materials for insulation. These polymeric foams are prepared by the polymerization of certain water-in-oil emulsions having a ratio of the water phase to the relatively high oil phase., commonly known in the art as "HIPE". As used herein, the polymeric foam materials resulting from the polymerization of such emulsions are referred to herein as "HIPE foams." The HIPE foam materials used in the present invention comprise a polymeric foam structure of interconnected open cells, generally hydrophobic, flexible, semi-flexible or rigid, non-ionic. These foam structures have: A) a specific surface area per volume of foam of at least about 0.01 m2 / cm3; B) a density of less than 0.05 g / cm3, approximately; and C) a glass transition temperature (Tg) of between about -20 ° and 90 ° C. The present invention provides the use of low density insulating foams prepared by the polymerization of a HIPE comprising a discontinuous water phase and a continuous oil phase, wherein the water to oil ratio is at least about 12: 1 . The water phase usually contains an electrolyte and an initiator solub in water. The oil phase generally consists of substantially water insoluble monomers polymerizable by free radicals, an emulsifier, and other optional ingredients defined below. The monomers are selected to impart the desired properties in the resulting polymeric foam, for example, glass transition (Tg) between about -20 ° and 90 ° C, mechanical integrity sufficient for the end use, and economical. In a preferred embodiment, the foams used can be pre-plowed, packed and shipped in a compressed, high density state, and will return upon activation (eg, by heat) to the original density of the foam. These foams are referred to herein as "compressible foams". These foams are described and claimed in the co-pending application of the United States Serial Number, filed on June 7, 1995, by T. DesMarais and J. Dyer. These compressible foams are particularly useful in the construction of insulation where fiber bundles are shipped rolled to widely dispersed locations and the total volume of the transport vehicle can be well filled before the vehicle's limit weight.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 of the drawings is a photomicrograph (250 X amplification) of a section cut from a representative polymeric foam useful in the present invention, made of HIPE having a water to oil weight ratio of 48: 1 and emptying to 57 ° C, and where the monomer component consists of a weight ratio of 12: 14: 62: 12 styrene: technical grade divinylbenzene (approximately 55% DVB, 45% ethyl styrene): 2-ethylhexyl acrylate : 1,4-butanediol dimethacrylate, and where emulsifiers were used in 5% (by weight of the oil phase) of diglycerol monoleate (DGMO) and 1% of commercial Span 85. Figure 2 of the drawings is a photomicrograph (1000 X amplification) of the foam of Figure 1. Figure 3 of the drawings is a photomicrograph (250 X amplification) of a section cut from a representative polymer foam useful in the present invention , made of HIPE which has a weight ratio of water to oil of 140: 1 and is emptied at 37 ° C, and wherein the monomer component consists of a 20:20:60 weight ratio of styrene: divinylbenzene technical grade (approximately 55% DVB, 45% ethyl styrene): 2-ethylhexyl acrylate, and where an emulsifier was used in 6% (by weight of the oil phase) of diglycerol monoleate (DGMO). Figure 4 of the drawings is a photomicrograph (1000 X amplification) of the foam of Figure 3.

DETAILED DESCRIPTION OF THE INVENTION I. Use of Polymeric Foams ^ In general Polymeric foams for the uses of the present invention are widely useful as thermal insulation materials. In thermal insulation applications, these polymeric foams can be provided as relatively rigid foam sheets or slabs, for use where some stiffness is desired, such as vacuum insulation panels or with insulation panels for building construction, which are nailed to a support structure. For these uses, the foams would generally be provided in a fully expanded state and would comprise those formulations that produce a relatively high Tg, from about 50 ° to about 80 ° C. The formulation would also contain relatively higher levels of hardening monomers, as described below. As rigid sheets, the foams of the present invention can be laminated or bonded to another support means to provide inflexibility, strength or better insulation properties.

For example, a thin sheet of reflective sheet may be laminated on one or both sides of the foam sheet to further reduce the heat transfer radiated through the structure. Also, these polymeric foams can be provided in any virtually desired form. Preferably, said forms will allow compression dewatering of the polymerized emulsion to limit the expense and effort associated with the removal of water.

B. Insulating Articles HIPE-derived polymeric foams are particularly useful in a variety of thermal applications, including appliances (refrigerators, ovens, blenders, toasters, freezers), transportation equipment (cars, trains, aircraft, ships), construction (insulation of wall, insulation of attics) and for many other uses. A preferred embodiment comprises the use of a continuous rabbing of said foam compressed to at least about one-third of its thinnest dimension, stored, shipped, and applied as an article of raw material in roll, and expanding after application by, either, time or heat to restore its original dimensions and insulating properties. Also, the foams for the uses of the present invention can be used within vacuum insulation panels to provide strength and inflexibility to the panel, without adding much mass that would provide a convective path of heat through the polymer structure. For these uses, it would be generally desirable to use versions of high Tg foams of the present invention, for example, between about 50 ° and 80 ° C. These foams can still be drained efficiently, by squeezing them if the water near the Tg is heated during the squeezing process. The ability to remove water from the foams of the present invention by squeezing is highly preferred to limit the cost and complexity of the process. Since the foams of the present invention can be manufactured with very low densities (eg, <; 0.020 g / cm3), these are particularly useful as structural fillers for vacuum insulation. The small cell sizes that are viable with these foams reduce the radiated heat transfer through the vacuum panel. The low density provides a relatively insignificant solid polymer through which thermal energy can be conducted. These two attributes are of particular significance in the present where the conduction through the gas of a foam is negligible.

C. Other Uses Also these foams can be used as insulators against acoustic or mechanical forces. When it is intended to be used as insulators against the transmission of acoustic and / or mechanical vibrations, these foams are particularly useful in that both the Tg of the material and the amplitude of transition can be optimized for the specific application. It is generally desirable that the Tg of the foam be closely aligned with the temperature and frequency of the midpoint of the acoustic energy or vibration to be damped. The foams of the present invention are easily "tuned" for this purpose, as described below. For example, if a continuous noise of 1000 Hz is to be damped at 25 ° C, the Tg of the foam measured at 1000 Hz should be 25 ° C. If the noise or vibration is a combination of frequencies (as is usually the case), or if damping is desired over a wider temperature scale, then the glass-to-plastic transition region should be as wide as possible. Alternatively, the foam can be subsequently treated with a second polymeric material to make a macroscopic internal penetration network, wherein both polymers will contribute to the sound / vibration damping in different regions of temperature and frequency. Additional descriptions of generic uses of foams as acoustic or mechanical shock insulators are given in Brandup, J .; Immergut, E.H. "Polymer Handbook", Second Edition, Wiley-Interscience, New York, NY, 1975, pages 240-242 and pages 210-216 and pages 286-325.

II. Polymeric Foams Insulators A. General Characteristics of the Foam The polymeric foams used in accordance with the present invention are of relatively open cell. This means that the individual cells of the foam are in complete communication, not obstructed with the adjacent cells. The cells, in said substantially open cell foam structures, have intercell openings or "windows" that connect one cell to another, within the foam structure. These foam structures of substantially open cell will generally have a cross-linked character, the individual cells being defined by a plurality of mutually connected, three-dimensionally branched frames. The strands of the polymeric material forming these branched webs can be referred to as "poles". Open cell foams having a typical post-type structure are shown by way of example in the photomicrographs of Figures 1 and 2. As used herein, a foam material is an "open cell" if at least 80% of the cells in the foam structure that are at least 1 μm in size are in fluid communication with at least one adjacent cell. In addition to having open cells, these polymeric foams are generally hydrophobic to inhibit the passage of aqueous fluids through the foam. The internal surfaces of the foam structures are made hydrophobic by removing surfactants and hydrophilizing salts left in the foam structure after polymerization, or through selected post-polymerization foam treatment processes, as described further ahead. The foams used according to the present invention are easily optimized to give them the desired properties in each specific application. The ease of control over a wide range of properties of these foams is never seen. As examples, these foams can be hydrophilic or hydrophobic (preferably hydrophobic); microcellular (<10μm) ascending through moderate cell diameters (ca. 100 μm); low density (0.05 g / cm3) to very low density (0.005 g / cm3); from rigid to flexible (corresponding, Tg raised to low Tg (subambient)); and from strong to weak. The foams can be provided as continuous sheets, rigid rigid boards, particles of various sizes, specific shapes, etc., as required for their final use. However, optimized, these foams avoid some deficiencies associated with the foaming methods described below. That is, they do not contain nitrogen in a way that incineration does not produce harmful gases, does not require CFC or volatile organic compound (VOC) materials during manufacture, they are easily produced in large quantities with reasonable economy as sheet material , roll material, foam particles and the like. In addition, the foams used in the present invention are inherently photostable. In a preferred embodiment, the polymeric foams can be prepared in the form of compressed polymeric foams which, upon heating or over time, expand and reach their total insulating capacity (here referred to as "compressible foams"). These crushed polymeric foams are usually obtained by removing the water phase from the polymerized HIPE foam through compression forces, and / or thermal drying and / or vacuum dewatering. After compression, and / or thermal drying and / or vacuum dewatering, followed by rapid freezing, the polymeric foam is in a compressed or unexpanded state. A key parameter of these compressible foams is their glass transition temperature (Tg). The Tg represents the midpoint of the transition between the vitreous and plastic states of the polymer. Foams that have a Tg greater than the temperature of use can be very resistant, but they will also be very rigid and potentially prone to rupture. Also, these foams typically take a long time to recover to the expanded state after they have been stored in a compressed state for extended periods. Although the final use of a particular foam is an important factor when determining the desired Tg of the foam, foams having a Tg of from about 0 to about 50 ° C are preferred. More preferred are foams having a Tg of from about 10 to about 40 ° C.

B. Foam Density Another important property of the insulating foams used in the present invention is their density. The "foam density" (ie in grams of foam per cubic centimeter of foam volume in the air) is specified here on a dry basis, unless otherwise indicated. Any suitable gravimetric procedure that will provide a mass determination of the solid foam material per unit volume of foam structure can be used to measure the density of the foam. For example, an ASTM gravimetric process described more fully in the Test Methods section of U.S. Patent 5,387,207 (Dyer et al.), Issued February 7, 1995 (incorporated herein by reference) is a method that can be used for density determination. Although foams can be made with virtually any density varying from below that of the air to solé less than the volume density of the polymer from which it is made, the foams of the present invention are most useful when they have a dry density in the expanded state less than about 0.05 g / cm 3, preferably between about 0.08 and about 0.004 g / cm 3, more preferably between about 0.038 and 0.013 g / cm 3, and most preferably about 0.03 g / cm 3.

C. Other Properties of Polymer Foam Foam cells, and especially cells that are formed by polymerizing an oil phase containing monomer surrounding water phase droplets relatively free of monomer, will often have a substantially spherical shape. The size or "diameter" of said spherical cells is a parameter commonly used to characterize foams in general. Since the cells in a given sample of polymeric foam will not necessarily be of approximately the same size; the average cell sizes, ie the average cell diameters, will usually be specified. A number of techniques are available to determine the average cell sizes of the foams. However, the most useful technique for determining cell size in foams involves a simple measurement based on the scanning electron photomicrograph of a foam sample. Figure 1, for example, shows a typical HIPE foam structure, according to the present invention in its expanded state. Superimposed on the photomicrograph is a scale representing a dimension of 20 μm. This scale can be used to determine the average cell sizes through an image analysis procedure. The measurements of the cell size given herein are based on the average cell size number of the foam in its expanded state, for example, as shown in Figure 1. The foams useful as insulating materials according to the present invention, they will preferably have a number average cell size less than about 100 μm, more preferably about 10 to 50 μm, and most preferably about 15 to about 35 μm.

D. Specific Surface Area Another key parameter of the foam is its specific surface area, which is determined both by the dimensions of the cell units in the foam and by the density of the polymer, and in this way is a way to quantify the total amount of solid surface provided by the foam. The specific surface area of capillary suction is determined by measuring the amount of capillary consumption of a liquid of a low surface tension (e.g. ethanol), which occurs within a foam sample of a known mass and dimensions. A detailed description of said method for determining the specific surface area of the foam through the capillary suction method is set forth in the Test Methods section of United States of America 5,387,207 (Dyer et al.), Issued on February 7, 1995, which is incorporated herein by reference. Other similar tests can be used with the insulation foams of the present invention to determine the specific surface area. The foams of the present invention have a capillary suction specific surface area of at least about 0.01 m2 / cm3, preferably at least about 0.025 m2 / cm3.

E. Compressible Foams With respect to foams that can be maintained in a compressed state, this state is maintained by keeping the polymeric foam substantially below the Tg of the polymer. In this state, the flow of the individual chains of the polymer is relatively slow. However, the thermosetting characteristic of these foams (deriving from a relatively high level of crosslinker incorporated therein) provides the memory of a preexisting expanded state. In this way, when heated or allowed to last without restriction, the foams will regain their original dimensions. These dimensions maintain the inherent low density by providing a useful insulating material. This attribute is particularly useful where the roll foam is to be shipped, stored and applied to cover a comparatively large area such as an attic of a residence. During these stages, it occupies considerably less volume than is characteristic of fiberglass blocks, for example. During or after the application, either the heat or the passage of time will restore their original dimensions and their insulating capacity. The Tg of the polymeric foam is obviously important for maintaining stability in the compressed state and still provides for re-expansion within a reasonable period or at achievable temperatures. Upon exposure to heat or the passage of time, the compressed foams used in a preferred embodiment recover their original dimensions and shape. This is attributable to the heat hardening nature of the polymer used to make the foam. Generally, the foams are compressed in a dimension, called the "Z direction", which is the thinnest dimension of a foam sheet, sliced. By recovering the original expanded dimensions of the foam, an "expansion factor" can be defined, which refers to the ratio of the thinnest dimension in the expansion against the compressed state. For these compressible foams, the expansion factor is at least about 3X, that is, the thickness of the foam in its expanded state is at least 3 times the thickness of the foam in its compressed state. Compressible foams typically have an expansion factor in the range of about 3X to about 10X. For comparison, compressed foams of fiberglass blocks typically have a recoverable expansion factor of only about 2x. As an example, a foam made by polymerizing a HIPE comprising 35% styrene, 20% divinyl benzene, and 45% 2-ethylhexyl acrylate, with a density of 0.020 and a Tg of 40 ° C, can be compressed when it is filled with water at 40 ° C and cooled immediately after the release of compression. The degree of compression is dictated by the geometry of the jaw rollers through which passes, the density of the foam, and, to a lesser extent, the temperature coefficient at which it is compressed. In this example, the foam can be compressed approximately 5X to approximately 20% of its original thickness. The compressed foam will retain this series almost indefinitely when stored at a temperature of about 8 ° C or more below the Tg of the foam (in this case, less than about 32 ° C). That is, the compressed foam will recover no more than about 10% of its original thickness over a period of at least about a week without restriction at room temperature (22 ° C). In other words, it will expand to no more than about 30% of its original thickness. In practice, the foams will grow much less for even longer periods of time, particularly if restricted by properly packing them in, for example, shrink wrap form. When the foam is heated to at least approximately its Tg (in this case, 40 ° C), it will recover virtually all of its original thickness, or at least about 80% of its original thickness, in a period of about one hour, preferably less. In practice, this foam would recover more than 90% of its original thickness when heated to at least about 40 ° C, in less than an hour. These conditions approximate what could be found, for example, in an attic in summer after the compressed foam has been released from the shrink wrap and applied as desired. lll. Preparation of Polymeric Foams from HIPE having Relatively High Water to Oil Ratios A. In General The polymeric foams useful in the present invention are prepared by the polymerization of HIPEs. The relative amounts of the water and oil phases used to form the HIPEs are, among many other parameters, important for determining the structural, mechanical and performance properties of the resulting polymeric foams. In particular, the water to oil ratio in the emulsion can influence the density, the cell size and the specific surface area of the foam and the dimensions of the poles that form the foam. The emulsions used to prepare the HIPE foams will generally have a volume to weight ratio of water to oil phase at a scale of from about 12: 1 to about 125: 1, more preferably from about 25: 1 to about 125: 1, most preferably about 30: 1. The process for obtaining these foams comprises the steps of: A) forming a water-in-oil emulsion at a temperature of about 30 ° C or higher, and under low shear mixing of: 1) an oil phase comprising: a ) from about 80 to about 98% by weight of a monomer component capable of forming a copolymer having a Tg value of from about -20 ° to about 90 ° C, the monomer component comprising: i) from about 10 to about 70 % by weight of a monofunctional monomer substantially insoluble in water, capable of forming an atactic amorphous polymer having a Tg of about 35 ° C or less; ii) from about 10% to about 40% by weight of at least one monofunctional comonomer substantially insoluble in water, capable of forming a homopolymer having a Tg of about 35 ° C or less; iii) from about 2% to about 50% by weight of a first polyfunctional crosslinking agent, substantially water insoluble, selected from the group consisting of divinylbenzenes and their analogues; and iv) from about 0% to about 15% by weight of a second polyfunctional crosslinking agent, substantially insoluble in water, selected from the group consisting of diacrylates of diols and their analogues; and b) from about 2% to about 20% by weight of an emulsifying component, which is soluble in the oil phase, and which is suitable to form a stable water-in-oil emulsion; 2) a water phase comprising from about 0.1% to about 20% by weight of a water-soluble electrolyte; And 3) a volume to weight ratio of water phase to oil phase in the range of about 12: 1 to about 250: 1; and B) polymerizing the monomer component in the oil phase of the oil in water emulsion to form a polymeric foam material. The polymeric foam material can be subsequently washed and dehydrated in an iterative manner to provide a dry, hydrophobic foam, which can be formed as desired. Typically, this training will comprise slicing or cutting into relatively thin sheets. These sheets can optionally be compressed, for example, continuously through pressure jaws, in a thin state and rolled into rolls. Preferred compressible sheets will retain their relatively thin compressed state until they are unwound, applied as desired, and any heating above their activation temperature (usually above the Tg of the polymer) or allowed to remain for a period of time. relatively long time, for example, for several weeks or months, depending on the ambient temperature. 1. Components of the Oil Phase The continuous oil phase of the HIPE comprises monomers that are polymerized to form the solid foam structure. This monomer component is formulated to be capable of forming a copolymer having a Tg of from about -20 ° to about 90 ° C., and preferably from about 15 ° to about SO C, more preferably from about 20 to about 40 ° C. (The method for determining Tg by Dynamic Mechanical Analysis (DMA) is described later in the Test Methods section). This monomer component includes: (a) at least one functional monomer whose atactic amorphous polymer has a Tg of about 25 ° C or less (see Brandup, J., Immergut, EH, "Polymer Handbook", 2nd edition, Wiley -lnterscience, New York, NY, 1975, 111-139); (b) at least one monofunctional comonomer to improve the stiffness or breaking strength of the foam; (c) a first polyfunctional interlacing agent; and (d) optionally a second polyfunctional crosslinking agent. The selection of particular types and amounts of monofunctional monomers and comonomers and polyfunctional crosslinking agents may be important for the performance of HIPE absorbent foams, which have the desired combination of structure, mechanical, and fluid handling properties, which make that these materials are suitable for use in the present invention. The monomer component comprises one or more monomers that tend to impart rubber-like properties to the resulting polymeric foam structure. These monomers can produce high molecular weight atactic amorphous polymers (greater than 10,000), having a Tg of about 25 ° C or less. Monomers of this type include, for example, (C4-C14) alkyl acrylates such as butyl acrylate, hexyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, (lauryl) acrylate, dodecyl, isodecyl acrylate, tetradecyl acrylate; aryl acrylates and alkaryl acrylates such as benzyl acrylate, nonylphenyl acrylate, alkyl (C6-C16) alkyl methacrylates such as hexyl methacrylate, octyl methacrylate, nonyl methacrylate, decyl methacrylate, isodecyl methacrylate, (lauryl) methacrylate of dodecyl, tetradecyl methacrylate, acrylamides such as N-octadecyl acrylamide; alkyl styrenes (C4-C12) such as p-n-octylstyrene and combinations of such monomers. Of these monomers, the most preferred are isodecyl acrylate, dodecyl acrylate, and 2-ethylhexyl acrylate. The monofunctional monomers will generally comprise from 10 to about 70%, most preferably from about 20 to 50%, by weight of the monomer component. The monomer component used in the oil phase of the HIPEs also comprises one or more monofunctional comonomers capable of imparting rigidity approximately equivalent to that provided by styrene to the resulting polymeric foam structure. The stiffer foams exhibit the ability to deform substantially without failure. These types of monofunctional comonomer may include styrene-based comonomers (eg, styrene and ethyl styrene), or other types of monomers such as methyl methacrylate, wherein related homopolymer is known for its illustrative rigidity. The preferred monofunctional comonomer of this type is a styrene-based monomer, the most preferred monomers of this type being styrene and ethyl styrene. The monofunctional "stiffness" comonomer will typically comprise about 10 to 70%, preferably about 20% to about 50%, most preferably about 30% to about 50%, by weight of the monomer component. In certain cases, the "stiffness" comonomer may also impart the desired rubber type properties to the resulting polymer. C4-C12 alkyl styrenes, and in particular p-n-octyl styrene, are examples of such comonomers. For said comonomers, the amount of these that can be included in the monomer component will be that of the typical monomer and comonomer combination. The monomer component also contains a first polyfunctional crosslinking agent (and optionally a second agent.) As with the monofunctional monomers and comonomers, the selection of the particular type and amount of the crosslinking agent is very important for the final realization of the preferred polymeric foams having the desired combination of structural, mechanical, and fluid handling properties.The first polyfunctional crosslinking agent can be selected from a wide variety of comonomers containing 2 or more activated vinyl groups, such as divinylbenzenes and their analogs.The useful divinylbenzene analogs herein includes, but is not limited to trivinylbenzenes, divinyl toluenes, divinylxylenes, divinylnaphthalenes, divinyl-alkylbenzenes, divinylphenanthrenes, divinylbiphenyls, divinyl-diphenylmethanes, divinylbenzyl, divinylphenyl ethers, divinyl diphenyl sulfides, divinylfurans, divinyl sulfide, divinyl lone, and mixtures thereof. Divinylbenzene is typically available as a mixture with ethyl styrene in proportions of about 55:45. These proportions can be modified in order to enrich the oil phase with one or the other component. In general, it is advantageous to enrich the mixture with the ethyl styrene component, while simultaneously reducing the amount of styrene in the monomer mixture. The preferred ratio of divinylbenzene to ethyl styrene is from about 30:70 and 55:45, most preferably from 35:65 to 45:55, approximately. The inclusion of higher levels of ethyl styrene imparts the required rigidity without increasing the Tg of the resulting copolymer to the extent that the styrene does. This first interlacing agent in general can be included in the oil phase of the HIPE in an amount of from about 2% to about 50%, preferably from about 10% to 35%, and most preferably from 15% to 25%, approximately, by weight of the monomer component. The second optional crosslinking agent can be selected from polyfunctional acrylates selected from the group consisting of di-acrylate diacrylates and analogs thereof. These crosslinking agents include methacrylates, acrylamides, methacrylamides and mixtures thereof. These include di-, tri-, and tetra-acrylates, as well as di-, tri-, and tetra-methacrylates, di-, tri-, and tetra-acrylamides, as well as di-, tri-, and tetra-methacrylamides; and mixtures of these crosslinking agents. Suitable acrylate and methacrylate crosslinkers can be derived from diols, triols and tetraols including 1,1-decanediol, 1,8-octanediol, 1,6-hexanediol, 1,4-butanediol, 1,3-butanediol, 1, 4-but-2-eneodiol, ethylene glycol, diethylene glycol, trimethylolpropane, pentaerythritol, hydroquinone, catechol, resorcinol, triethylene glycol, polyethylene glycol, sorbitol, and the like. (The acrylamide and methacrylamide crosslinking agents can be derived from the equivalent diamines, triamines, and tetramines). Preferred diols have at least 2, preferably at least 4, and most preferably 6 carbon atoms. This second crosslinking agent can generally be included in the oil phase of the HIPE in an amount of from 0 to about 15%, by weight of the monomer component. The main portion of the oil base of the HIPEs will comprise the aforementioned monomers, comonomers and crosslinking agents. It is essential that these monomers, comonomers and crosslinking agents are substantially insoluble in water, so that they are mainly soluble in the oil phase and not in the water phase. The use of said substantially insoluble monomers in water ensures that HIPEs of appropriate characteristics and stability will be obtained. Of course, it is highly preferred that the monomers, comonomers and crosslinking agents used herein are of the type such that the resulting polymeric foam is suitably non-toxic and appropriate and chemically stable. These monomers, comonomers and crosslinking agents should preferably have little or no toxicity if present at very low residual concentrations, during the processing and / or use of the post-polymerization foam. Another essential component of the oil phase is an emulsifying component comprising at least one primary emulsifier. Suitable primary emulsifiers are well known to those skilled in the art. Particularly preferred emulsifiers include Span 20®, Span 40®, Span 60® and Span 80®. These are nominally sorbitan esters derived from lauric, myristic, stearic and oleic acids, respectively. Other preferred emulsifiers include the diglecerol esters derived from monooleate, monopalmitate and monoisostearate acids. A preferred emulsifier is dimethyl ammonium ditallow methyl sulfate. Also, mixtures of these emulsifiers are particularly useful, as are purified versions of each, specifically sorbitan esters containing minimum levels of isosorbide and polyol impurities. In addition to these primary emulsifiers, secondary emulsifiers can optionally be included in the emulsification component. Again, those skilled in the art will recognize that any variety of known emulsifiers can be used. These emulsifiers are at least co-soluble with the primary emulsifier in the oil phase. Secondary emulsifiers can be obtained or prepared commercially using methods known in the art. Preferred secondary emulsifiers are dimethyl dimethyl ammonium methylsulfate and dimethyl ammonium dichloride methylchloride. When these optional secondary emulsifiers are included in the emulsifying component, are in a weight ratio of primary to secondary emulsifier from about 50: 1 to about 1: 4, preferably from about 30: 1 to 2: 1. As indicated, those skilled in the art will recognize that any emulsifier may be used in the processes for making the foams of the present invention. For example, see U.S. Patent 5,387,207 and copending U.S. Patent Application 08 / 370,695, filed January 10, 1995 by Stone et al. The oil phase used to form the HIPEs comprises from about 85 to about 98% by weight of the monomer component and from about 2 to about 15% by weight of the emulsifier component. Preferably, the oil phase will comprise from about 90 to about 97% by weight of a monomer component and from about 3 to about 10% by weight of the emulsifier component. The oil phase can also contain other optional components. One such optional component is an oil-soluble polymerization initiator of the general type well known to those skilled in the art, such as described in the US Pat.

United States of America 5,290,820 (Bass et al.), Issued on the 1st. March 1994, which is incorporated herein by reference. A preferred optional component is an antioxidant such as a Disabled Amine Light Stabilizer (HALS), such as bis- (1, 2,2,5,5-pentamethylpiperidinyl) sebacate (Tinuvin-765®) or an Impaired Phenolic Stabilizer. (HPS) such as lrganox-1076® and t-butylhydroxyquinone. Another optional component is a plasticizer such as dioctyl azelate, dioctyl sebacate or dioctyl adipate. Yet another optional ingredient is filler particles that can harden the polymer and / or increase its thermal insulation properties. Examples of filler particles include aluminum, titanium dioxide, carbon black, graphite, calcium carbonate, talc and the like. Generally, particles that help make the polymer opaque in the infrared region, such as carbon black and graphite, are preferred. Other optional components include dyes (colorant or pigments), fluorescent agents, opacifying agents, chain transfer agents and the like. 2. Components of the Water Phase The discontinuous water internal phase of the HIPE is generally an aqueous solution containing one or more dissolved components. A dissolved essential component of the water phase is a water soluble electrolyte. The dissolved electrolyte minimizes the tendency of monomers, comonomers and crosslinkers that are mainly soluble in oil to also dissolve in the water phase. This, in turn, is believed to minimize the degree to which the polymeric material fills the cell windows in the adjoining oil / water surfaces formed by the droplets of the water phase during polymerization. Thus, the presence of the electrolyte and the ionic strength resulting from the water phase is believed to determine if and to what degree the resulting preferred polymeric foams can be open cell. Any electrolyte capable of imparting ionic resistance to the water phase can be used. Preferred electrolytes are mono-, di- or trivalent organic salts, such as water-soluble halides, for example, chlorides, nitrates and sulfates of alkali metals or alkaline earth metals. Examples include sodium chloride, calcium chloride, sodium sulfate and magnesium sulfate. Calcium chloride is most preferred for use in the preparation of HIPEs. Generally, the electrolyte will be used in the water phase of the HIPEs at a concentration in the range of about 0.2 to about 20% by weight of the water phase. Most preferably, the electrolyte will comprise from about 1 to about 20% by weight of the water phase. The HIPEs will also typically contain an effective amount of a polymerization initiator. Said initiator component is generally added to the water phase of the HIPEs and can be any free radical, water soluble, conventional initiator. These include peroxygen compounds such as sodium, potassium and ammonium persulfates, hydrogen peroxide, sodium peracetate, sodium percarbonate and the like. Conventional redox initiator systems can also be used. Such systems are formed by combining the above peroxygen compounds with reducing agents such as sodium bisulfite, L-ascorbic acid or ferrous salts. The initiator may be present in an amount of up to 20 mol% based on the total moles of polymerizable monomers present in the oil phase. Most preferably, the initiator is present in an amount of about 0.001 to about 10 mol% based on the total moles of the polymerizable monomers in the oil phase. 3. Hydrophilizing Surfactants and Hydratable Salts The polymer that forms the HIPE foam structure will preferably be substantially free of polar functional groups. This means that the polymeric foam will have a relatively hydrophobic character. When these foams are going to be used as insulating materials, water resistance is a desired characteristic.

The removal of the residual emulsifier and / or salt following the polymerization is generally desired, in the manner described below.

B. Processing Conditions for Obtaining HIPE Foams The preparation of foams typically involves the steps of: 1) forming a highly stable internal phase emulsion (HIPE); 2) polymerizing / curing this suitable emulsion to form a solid polymeric foam structure; 3) optionally washing the solid polymer foam structure to remove the original water residual phase, emulsifier and salts from the polymeric foam structure and, if necessary, treating the polymeric foam structure; and 4) then dehydrating this polymeric foam structure. 1. HIPE Formation HIPE is formed by combining the oil and water phase components in the weight ratios previously specified. The oil phase will typically contain the requisite monomers, comonomers, crosslinkers and emulsifiers, as well as optional components such as plasticizers, antioxidants, flame retardants, and chain transfer agents. The water phase will typically contain electrolytes and polymerization initiators. The HIPE can be formed from the combined oil and water phases by subjecting them to shear agitation. The shear agitation is also applied to such a degree and for a time necessary to form a stable emulsion. Said process can be conducted in either intermittent or continuous form, and is generally carried out under suitable conditions to form an emulsion, wherein the droplets of the water phase are dispersed to such an extent that the resulting polymeric foam will have the requisite characteristics. of cell size and other structural characteristics. Emulsification of the oil and water phase combination will often involve the use of a mixing or stirring device, such as a pin propellant. A preferred method for forming said HIPEs involves a continuous process that combines and emulsifies the oil and water phases of requirement. In said process, a liquid stream comprising the oil phase is formed. Consequently, a separate liquid stream comprising the water phase is also formed. Then, the two streams are combined in a suitable mixing chamber or zone, so that the pre-specified water-to-oil phase weight ratios are obtained. In the mixing zone or chamber, the combined streams are generally subjected to low shear agitation provided, for example, through a pin driver of suitable configurations and dimensions. The shear stress will typically be applied to the combined water / oil phase stream at an appropriate rate. Once formed, the stable liquid HIPE can then be removed from the mixing zone or chamber. This preferred method for forming HIPEs through a continuous process is described in more detail in U.S. Patent 5,149,720 (DesMarais et al.), Issued September 22, 1992, which is incorporated herein by reference. Also see request from the United States of Copendent America series No. 08/370694 (Thomas A. DesMarais), filed January 10, 1995 (incorporated herein by reference), which describes an improved continuous process having a closed loop recirculation circuit for the HIPE. 2. Polymerization / Healing of HIPE The formed HIPE will generally be collected or emptied into a suitable container, container or reaction region, which will be polymerized or cured. In one embodiment, the reaction vessel comprises a tray constructed of polyethylene, from which finally the polymerized / cured solid foam material can be easily removed for further processing after the polymerization / cure has been carried out to the desired degree. Preferably, the temperature at which the HIPE is emptied into the container is approximately equal to the polymerization / cure temperature. Suitable polymerization / curing conditions will vary depending on the monomer and other development of the oil and water phases of the emulsion (especially the emulsifier systems used), and the type and amounts of polymerization initiators used. Frequently, however, suitable polymerization / cure conditions will involve maintaining the HIPE at elevated temperatures approximately above 30 ° C, preferably above 35 ° C, for a period ranging from about 2 to 64 hours , most preferably from 2 to 48 hours, approximately. HIPE can also be cured in stages as described in U.S. Patent 5,189,070 (Brownscombe et al.), Issued February 23, 1993, which is incorporated herein by reference. A particular advantage of the more robust emulsifier systems used in these HIPEs is that the polymerization / cure conditions can be carried out at higher temperatures of about 50 ° C or higher, more preferably 60 ° C or higher. Typically, the HIPE can be polymerized / cured at a temperature of from about 60 ° C to about 99 ° C, more typically from about 65 ° C to about 95 ° C. An open-cell, porous, water-filled HIPE foam it is typically obtained after polymerization / curing in a reaction vessel, such as a tray. This polymerized HIPE foam is typically cut or sliced into a sheet-like shape. Polymerized HIPE foam sheets are easier to process during the subsequent steps of treatment / washing and dehydration, as well as to prepare the HIPE foam for use in materials for insulation. The polymerized HIPE foam is typically cut / sliced to provide a cut thickness in the range from about 0.2032 to about 8.89 cm. The subsequent dehydration by compression of the foam in the Z direction typically leads to HIPE foams having a thickness in the range of about 10 to about 17% of their cut thickness. 3. Treatment / Washing of HIPE Foam The polymerized HIPE foam formed will usually be filled with the wastewater phase material to prepare the HIPE. The residual water phase material (generally an aqueous electrolyte solution, residual emulsifier, and polymerization initiator) must be removed prior to the processing and use of the foam. The removal of this original water phase material will usually be done by compressing the foam structure to compress the residual liquid, and / or by washing the foam structure with water or other aqueous washing solutions. Frequently, several compression and washing steps will be used, v. gr., from 2 to 4 cycles. It is preferable that the water used in these washes be heated to at least about the Tg of the polymer to maintain its flexibility and docility during compression dewatering and to reduce and avoid damage to the foam structure. 4. Dehydration of the Foam After the HIPE foam has been treated / washed, it will generally be dehydrated. Dehydration can be achieved by compressing the foam to squeeze the residual water, subjecting the foam and water at the same temperature from about 60 ° to about 200 ° C, or by microwave treatment, by thermal vacuum dehydration or by a combination of compression and drying / microwave / vacuum dewatering techniques. These HIPE foams are typically dehydrated by compression to a thickness of about 1/3 (33%) or less of their fully expanded thickness. The dehydration step will generally be performed until the HIPE foam is ready to use and is as dry as practicable. Frequently, such compression dehydrated foams will have a water content (moisture) as low as possible, from about 1% to about 15%, more preferably from about 5% to about 10% by weight, based on a weight basis. dry.

IV. Test Methods A. Dynamic Mechanical Analysis (DMA) The DMA was used to determine the Tgs of the polymers including the polymeric foams, the samples of the foams were sliced into blocks with a thickness of 3-5 mm, and they were washed 3- 4 times in distilled water, expressing the fluid through press rolls between each wash.The resulting foam blocks were allowed to air dry.The dry foam slices were applied a core to produce cylinders with a diameter of 25 mm. Cylinders were analyzed using a Rheometrics RSA-II dynamic mechanical analyzer equipment, in a compression mode using parallel plates with a diameter of 25 mm.The instrument parameters used were the following: Temperature step from approximately 85 ° C to -40 ° C in steps of 2.5 ° C Soaking intervals between temperature changes of 125-160 seconds Dynamic voltage setting from 0.1% to 1.0% (usually 0.7%) Frequency setting at 1.0 radians / second Setting of self-tension in dynamic force mode of static force tracking with an initial static force setting at 5 g. The glass transition temperature was taken as the maximum point of the tangent curve of loss versus temperature.

B. Expansion Factor The expansion factor can be quantified by measuring the thickness of a foam sample in the crushed (compressed) state and in the expanded state. The ratio of the expanded thickness to the initial crushed thickness is the expansion factor. The foam sample in its compressed state is placed on a flat granite base under a suitable calibrator to measure the thickness of the sample. The calibrator is set until a pressure of 0.08 psi is exerted on the sample. Any calibrator fitted with a foot having a circular surface area of at least 6.5 cm2 and capable of measuring the thickness at 0.025 mm can be used. Examples of these calibrators are an Ames 482 Model (Ames Co.; Waltham, MA) or an Ono-Sokki model EG-225. (Ono-Sokki Co., Ltd., Japan). The initial thickness (Xo) is recorded. The assembly including the foam is then placed inside an oven set at T = Tg + 20 ° C. After 60 minutes, the expanded thickness (X1) is recorded. The expansion factor (EF) is calculated as EF = X1 Xo. The expansion factor can be recorded after storage at T = Tg + 20 ° C for 1 day or longer to ensure that full recovery is obtained to the dimensions of an unexpanded sample. Generally, the sample is left at the higher temperature until no further re-expansion is recorded.

C. Specific Surface Area As discussed above, a detailed description of a method for determining the specific surface area through the capillary suction method is set forth in the TEST METHODS section of U.S. Patent No. 5,387,207.

V. Specific Examples These examples illustrate the specific preparation of HIPE foams according to the present invention.

EXAMPLE 1 Preparation of Foam from HIPE A) Preparation of HIPE The 378 liters of anhydrous calcium chloride water (36.32 kg) and potassium persulfate (189 g) were dissolved. This provides the water phase stream that will be used in a continuous process to form a HIPE emulsion. To a monomer combination comprising styrene (1400 g), 55% technical grade divinylbenzene (1200 g), and 2-ethylhexyl acrylate (2400 g), Span 40® (480 g) was added. After mixing, this solution is allowed to stand overnight. The supernatant is removed from the entire mixture and used in the oil phase as the emulsifier to form a HIPE emulsion. (Any resulting sticky residue is discarded) Separate streams from the oil phase (25 ° C) and the water phase (42 ° -44 ° C) were fed to a dynamic mixing apparatus. The complete mixing of the combined streams in the dynamic mixing apparatus was achieved through a pin impeller. At this scale of operation, a suitable pin propeller comprises a cylindrical arrow with a length of approximately 21.6 cm with a diameter of approximately 1.9 cm. The arrow holds 4 rows of pins, two rows having 17 pins and two rows having 16 pins, each having a diameter of 0.5 cm extending out from the central axis of the arrow to a length of 1.5 cm. The pin propeller is mounted on a cylindrical sleeve which forms the dynamic mixing apparatus, and the pins have a clearance of 0.8 mm from the walls of the cylindrical sleeve. A spiral static mixer is mounted downstream of the dynamic mixing apparatus to provide back pressure in the dynamic mixer and to provide improved incorporation of the components in the emulsion that is ultimately formed. The static mixer is 35.6 cm long with an external diameter of 1.3 cm. The static mixer is a TAH Industries Model 070-821, modified, by 6.1 cm cuts. The fixing of the combined recirculation and mixing apparatus is filled with oil phase and water phase at a ratio of 3 parts of water to one part of oil. The dynamic mixing apparatus is vented so that air can escape while the apparatus is fully filled. The flow rates during filling are 1.89 gr / sec of oil phase and 5.68 cm3 / sec of water phase. Once the apparatus is full, agitation begins in the dynamic mixer, with the propeller spinning at 1800 rpm. The flow rate of the water phase was then increased steadily at a rate of 45.4 cm3 / sec and the flow rate of the oil phase was reduced to 0.82 g / sec over a period of about 2 minutes. The back pressure created by the dynamic and static mixers at this point is 92 kPa. The speed of the propellant was then stably reduced at a speed of 1200 rpm for a period of time of 120 seconds. The back pressure fell to 37 kPa. At this point, the speed of the propeller increased instantaneously up to 1800 rpm. The back pressure of the system was increased to 44 kPa and remained constant later. The resulting HIPE has a water to oil ratio of about 55: 1.

B) Polymerization / Healing of HIPE The HIPE from the static mixer was collected in a round polypropylene tube, with a diameter of 43 cm and a height of 10 cm, with a concentric insert made of Celcon plastic. The insert has a diameter of 12.7 cm at its base and a diameter of 12 cm in its upper part, and a height of 17.1 cm. Tubes containing HIPE are kept in a room at 65 ° C for 18 hours for cure and provide a polymeric HIPE foam.

C. Foam Washing and Dehydration The cured HIPE foam was removed from the tubes. The foam at this point has a residual water phase (containing dissolved emulsifiers, electrolyte, initiator residues, and initiator) of about 50-60 times (50-60 X) the weight of the polymerized monomers. The foam was sliced with a saw blade with a sharp reciprocal movement, in sheets with a thickness of 0.5 cm. These sheets were then subjected to compression in a series of two porous press rolls equipped with a vacuum, which gradually reduces the residual water phase content of the foam to approximately 6 times (6X) the weight of the polymerized monomers. At this point, the sheets are then resaturated with water at 60 ° C, they are squeezed in a series of three porous press rolls equipped with vacuum at a water phase content of about 4X. Optionally, the water used to restore the foam contains approximately 1% sodium bicarbonate. This helps to react with any residual calcium chloride that would tend to make the hydrophilic washed foams and form non-hygroscopic calcium carbonate, insolube. The CaCl2 content of the foam is less than about 1%. The HIPE foam remains compressed after the final pressing to a thickness of approximately 0.048 cm. The foam is then air dried for approximately 16 hours. This drying reduces the moisture content to about 1 to 8% by weight of the polymerized material. In the compressed state, the density of the foam is about 0.14 g / cm3. When expanded, the foam has a dry density of about 0.018 g / cm3 and has a vitreous transition temperature of 50 ° C.

EXAMPLE 2 Preparation of the Foam from a HIPE A) Preparation of HIPE Anhydrous calcium chloride (36.32 kg) and potassium persulfate (189 g) were dissolved in 378 liters of water. This provides the water phase current that will be used in a continuous procedure to form the HIPE. To a combination of monomer comprising distilled divinylbenzene (40% divinylbenzene and 60% ethyl styrene) (2100 g), 2-ethylhexyl acrylate (3300 g) and hexanediol diacrylate (600 g) were added a diglycerol monooleate of very high purity (360 g) and Tinuvin 765 (30 gr). The diglycerol monooleate emulsifier (Grindsted Products; Braband, Denmark) comprises approximately 81% diglycerol monooleate, 1% other diglycerol monoesters, 3% polyols, and 15% other polyglycerol esters, imparts a stress value interfacial oil / water minimum of approximately 2.5 dynes / cm and has a critical oil / water aggregation concentration of approximately 2.9% by weight. After mixing, this combination of emulsifiers is allowed to stand overnight. No visible residues were formed and the entire mixture was removed and used as the oil phase as the emulsifier in the formation of the HIPE. The separated streams of the oil phase (25 ° C) and the water phase (53 ° -55 ° C) were fed to a dynamic mixing apparatus as in Example 1. A part of the material exiting the dynamic mixing apparatus is removed and introduced into a recirculation zone, as shown in Figure 1 of the United States patent application, co-pending, serial number 08 / 370,694, filed on January 10, 1995, by T. DesMarais, which is incorporated herein by reference, to the point of entry of the oil phase and water phase flow streams to the dynamic mixing zone. The recirculation and mixing apparatus combined with oil phase and water phase is filled at a ratio of 3 parts of water to one part of oil. The dynamic mixing apparatus is vented so that air can escape while the apparatus is fully filled. The flow rates during filling are 3.78 g / sec of oil phase and 11.35 cm3 / sec of water phase with approximately 15 crrl / sec in the recirculation circuit. Once the device is full, the flow rate of the water phase is cut in half to reduce the pressure formed while the ventilation is closed. Agitation then starts in the dynamic mixer, with the propeller spinning at 1800 rpm. The flow rate of the water phase was then increased steadily at a rate of 45.4 cm3 / sec over a period of about 1 minute, and the flow rate of the oil phase was reduced to 0.757 g / sec over a period of approximately 2 minutes. The recirculation rate was stably increased to approximately 45 cm3 / sec during the last period of time. The back pressure created by the static and dynamic mixers at this point is approximately 69 kPa. The speed of the Waukesha pump is then stably reduced to a yield of a recirculation rate of approximately 11 cm3 / sec.

B) Polymerization / Healing of HIPE The formed emulsion resulting from the static mixer at this point was collected in a round polypropylene tube, with a diameter of 43 cm and a height of cm, with a concentric insert made of Celcon plastic. The insert has a diameter of 12.7 cm at its base and a diameter of 12 cm in its upper part, and a height of 17.1 cm. The tubes containing the emulsion are kept in a room at 65 ° C for 18 hours for the polymerization of the emulsion in the containers to form the polymeric foam.

C. Foam Washing and Dehydration The cured HIPE foam was removed from the tubes. The foam at this point has a residual water phase (containing dissolved emulsifiers, electrolyte, initiator residues, and initiator) of about 50-60 times (50-60 X) the weight of the polymerized monomers. The foam was sliced with a saw blade with a sharp reciprocal movement, in sheets with a thickness of 0.406 cm. These sheets were then subjected to compression in a series of two porous press rolls equipped with a vacuum, which gradually reduces the residual water phase content of the foam to approximately 6 times (6X) the weight of the polymerized monomers. At this point, the sheets are then resaturated with water at 60 ° C, they are squeezed in a series of three porous press rolls equipped with vacuum at a water phase content of about 4X. The CaCl2 content of the foam is less than 1%. The HIPE foam remains compressed after the final pressing to a thickness of approximately 0.053 cm. The foam is then air dried for approximately 16 hours. This drying reduces the moisture content to about 9 to 17% by weight of the polymerized material. At this point, the foam sheets are very drapable. The foam also contains about 5% by weight of residual emulsifier of diglycerol mooleate. In the crushed state, the density of the foam is about 0.14 g / cm3. When expanded, the foam has a dry density of approximately 0.018 g / cm3 and has a glass transition temperature of 23 ° C.

EXAMPLES 3 TO 11 Preparation of HIPE Foams from Different Monomers Absorbent foams are prepared from HIPEs having variable monomer components, using procedures similar to those described in Example 1 and 2 above. The formulations of the monomer, the water to oil (W: O) ratios, and the resulting Tg are shown in Table 1. Table 1. Composition and Tq of the Foam STY: Styrene, available from Aldrich Chemical Corp. DVB: Divinylbenzene, based on 55% purity with 45% ethylstyrene as impurity; available from Dow Chemical Corp. EHA: 2-ethylhexyl acrylate available from Aldrich Chemical Corp. * Determined through Mechanical Dynamic Analysis at 1.0 radians / second.

EXAMPLES 12 TO 16 Preparation of HIPE Foams from Different Monomers Additional foams of the present invention are prepared essentially as described in Example 1. The insulating properties of these foams were measured by ASTM C177-85. The results are shown in Table 2. Table 2. Insulation values for the foams (** Calculated using DMA) (** Units are mW (mK), calculated using ASTM C177-85) a: DVB 55% pure b was used: DVB 50% pure c was used: 12% of 1 was used, 6-hexanedioldiacrylate The data shows excellent thermal insulation properties for the foams of the present invention.

EXAMPLE 17 A continuous sheet of foam 12 inches wide and 3 inches thick was prepared from a HIPE comprising 40% styrene, 20% DVB and 40% EHA in a water to oil ratio of 50: 1 by the procedure described in Example 1. This foam is dehydrated while being heated (ca 40oC) by passing it through the compression dewatering press rolls with successive 2"spaces, 1", 0.5" and 0.3". The foam slice retains a thickness at that stage of approximately 0.5". The continuous foam slice is then laminated to a 0.01"thick aluminum sheet and rolled into a ring approximately 2.5" in diameter. This is then packed in shrink wrap wrap. The foam remains stable in this configuration through the warehouse, shipping and retail deployment and application. The application takes the form of unrolling the product and inserting it between the roof beams in a residential attic at the desired cutting lengths. The product at this point is still approximately 0.5"thick.The high temperature in the attic causes a favorable rapid reexpansion to the original thickness and density, 3" and 0.020 g / cm3, respectively, of the foam. This serves as an excellent insulating material, handled conveniently from the manufacturer to the end use.

Claims (12)

1. - The use of a polymer foam material as an insulator, wherein the foam material has A) a specific surface area per foam volume of at least 0.01 m2 / cm 3; B) a dry density of less than 0.05 g / cm3; and C) a glass transition temperature (Tg) between -20 ° and 90 ° C.

2 - The use of a polymeric foam material as an insulator, wherein the foam material has A) a specific surface area per volume of foam of at least 0.01 m2 / cm 3; B) a dry density of less than 0.05 g / cm3; and C) a glass transition temperature (Tg) between -20 ° and 90 ° C; and wherein the polymeric foam material is prepared by the process comprising the steps of: A) forming a water-in-oil emulsion at a temperature of 30 ° C or higher, and under low shear mixing of: 1) a oil phase comprising: a) from 80 to 98% by weight of a monomer component capable of forming a copolymer having a Tg value of -20 ° to 90 ° C, the monomer component comprising: i) of 10 70% by weight of a monofunctional monomer substantially insoluble in water, capable of forming an atactic amorphous polymer having a Tg of 35 ° C or less; ii) from 10% to 70% by weight of at least one monofunctional comonomer substantially insoluble in water, capable of imparting hardening equivalent to that provided by styrene; iii) from 2% to 50% by weight of a first polyfunctional crosslinking agent, substantially insoluble in water, selected from the group consisting of divinylbenzenes and their analogues; and iv) from 0% to 15% by weight of a second polyfunctional crosslinking agent, substantially insoluble in water, selected from the group consisting of diacrylates of diols and their analogues; and b) from 2% to 20% by weight of an emulsifying component, which is soluble in the oil phase, and which is suitable to form a stable water-in-oil emulsion; 2) a water phase comprising from 0.1% to 20% by weight of a water-soluble electrolyte; and 3) a volume to weight ratio of water phase to oil phase in the range of about 12: 1 to about 250: 1; and B) polymerizing the monomer component in the oil phase of the oil in water emulsion to form a polymeric foam material.

3. The use according to claim 1, wherein the foam material has a glass transition temperature (Tg) of 0 ° to 50 ° C.

4. The use according to claim 1, wherein the foam material has a number average cell size less than 100 μm.

5. - The use according to claim 4, wherein the foam material has a number-average cell size from 10 μm to 50 μm, preferably from 15 μm to 35 μm.

6. The use according to claim 5, wherein the foam material has a glass transition temperature of 10 ° to 40 ° C.

7 '.- The use of a polymeric, hydrophobic foam material, such as an insulator, wherein the foam material has: A) a specific surface area per foam volume of at least 0.025 m2 / cm3; B) a dry density of 0.08 g / cm3 at 0.004 g / cm3; and C) a vitreous transition temperature (Tg) between 0 ° and 50 ° C; and D) a number average cell size of 10 μm to 50 μm.

8. The use according to claim 2, wherein the monomer component used in step (a) comprises from 10% to 70% functional comonomer (ii), preferably from 20% to 50% functional comonomer ( ii).

9. The use according to claim 8, wherein the comonomer component used in step (A) comprises from 20% to 50% functional comonomer (i).

10. The use according to claim 9, wherein the comonomer component used in step (A) comprises from 10% to 30% of crosslinking agent (iii). 1.

The use according to claim 2, wherein the monofunctional monomer (i) of the monomer component is selected from the group consisting of 2-ethylhexyl acrylate, isodecyl acrylate, lauryl acrylate, and lauryl methacrylate.; the monofunctional comonomer (ii) of the monomer component is selected from the group consisting of styrene, ethyl styrene and p-n-octylstyrene; and the first interlacing agent (iii) of the monomer component is selected from the group consisting of divinylbenzene, trivinylbenzene, divinyl toluene and divinylxylene.

12. The use according to claim 2, wherein the volume to weight ratio of the water phase to the oil phase is in the range of 25: 1 to 125: 1.