GB2136824A - Liquid fireproofing adhesive composition and process for manufacture - Google Patents

Abstract

A fireproof adhesive material is provided which accomplishes fiber encapsulation and permits the development of spray-on type fireproof insulation. The fireproof adhesive material incorporates a predetermined quantity of sodium silicate in liquid form with which is mixed a quantity of surfactant/water solution sufficient to render the cured fireproof adhesive flexible and to provide for emulsification in the liquid state thereof. The adhesive also includes a sufficient quantity of silicone water repellent to render the cured adhesive durable, chemical resistant and water repellent. Further, the adhesive material may include a liquid stabilizer plasticizer compound to enhance the flexibility of the cured adhesive. For odour control, a quantity of a malodour control agent may also be incorporated.

Description

SPECIFICATION Liquid fireproofing adhesive composition and process for manufacture This invention relates generally to fireproofing adhesive materials.

Due to the extensive loss of life and property typically caused by fires, a large number of materials have been developed as fireproof coating which have been somewhat successful in retarding the spread of flame. Virtually all the known fireproof insulation materials are combustible to some degree or have a relatively limited heat retarding thermal capability.

Moreover, many of the materials developed liberate hazardous toxic fumes when subjected to fire and are thus disadvantageous from the standpoint of pulmonary hazard.

It has also been considered desirable to provide a thermal insulation material which may also function as a fireproof adhesive and which is applicable as an integral constituent of interior coatings for metal buildings and other relatively smooth flexible surfaces. In many cases, it is virtually impossible to provide a material having efficient flexibility and adhesive character for attachment to the smooth surfaces of a sheet metal building and which are also of fireproof nature. Generally, fireproof materials are of rigid character due to their typical silaceous content, thereby rendering them relatively unsuitable as a fireproof adhesive for use on flexible objects and surfaces.

Another area of significant concern is the recent discovery that asbestos fibres and fibrils have a carcinogenic character and are perhaps responsible for a large number of human deaths due to lung cancer resulting from an occupation where prolonged contact with asbestos materials occurred. It is well known that many private and public buildings contain wall and ceiling structures which include asbestos materials. It has been determined that these materials continuously liberate asbestos fibres and fibrils which could represent a hazard to persons occupying the premises especially for prolonged periods of time. It is desirable therefore to provide a material or a combination of materials that may be utilized to accomplish efficient fireproofing, thermal insulation and protection against asbestos contamination.Heretofore, it has been believed impractical to provide a single material having efficient protective capabilities in all three of these areas. The present invention therefore relates to a material having efficient qualities in each of these three areas of public concern.

Fireproofing As mentioned above, various materials have been utilized to provide substantially fireproof coatings on wall and ceiling structures df buildings and on metal structural support members in an attempt to provide a fire retarding capability that, in effect, retards the spread of flame.

These materials are intended to limit the development of heat to such extent that fire spreading and development will be retarded thus to provide firemen with ample time to reach the scene and extinguish the fire before substantial damage has been done. In most cases, a material having fire retarding capability is required to pass successfully tests to determine the capability of the material to retard the development and spreading of fire. One such test is the American Society for Testing and Materials E119-80 Standard Methods of Fire Test of Building Constructions and Materials. This test is intended to provide data to enable regulatory agencies to determine the suitability of assemblies for use in locations where fire resistance of a specified duration is required.This standard is not used to measure and describe the properties or assemblies in response to heat and flame under controlled laboratory conditions. It is also not used to describe or appraise the fire hazard of materials or assemblies under actual conditions.

The results of this test are typically used as elements of fire risk assessment which takes into account all the factors which are pertinent to an assessment of the fire hazard of a particular end use. Exposure may not be representative of all fire conditions, which may vary with changes in the amount, nature and distribution of fire loading ventilation, compartment size and configuration, and heat sink characteristics of the compartment. It does, however, provide a relative measure of fire performance of assemblies under the specified fire exposure conditions. Any variations for the conditions that are tested may substantially alter the performance characteristics of the assembly.In this test, a fire, typically developed by natural gas, is directed on an insulated surface and thermocouples opposite the insulated surface are used to measure temperature increase as the fire is continued. A material is said to fail this test if the thermocouples show a temperature rise to 121"C (250by) within a predetermined minimum period of time. Various other tests are also conducted to determine the heat insulation and fire retarding capability of materials. For the most part, it is extremely difficult for any known fireproofing coating material to achieve a fire rating approaching one hour.

Heat insulation Another area of concern is the capability of a fire proofing material also to function for the purpose of heat insulation and to remain in place even on flexible surfaces such as the interior walls of a sheet metal building. It is well known that the metal of sheet metal buildings tends to radiate heat when heated during ambient conditions such as hot summer days. tt has been found practical to provide the interior surfaces of metal buildings with coatings of thermal insulation material to retard heat radiation. Most thermal materials capable of adhering to the flexible interior metal wall structures of sheet metal buildings are capable of providing only minimal protection from the standpoint of fireproofing.In some cases, thermal insulation material is composed of urethane foam, a highly inflammable material which yields toxic gases when aflame. It is desirable therefore to provide a fireproof coating material which also functions as a heat insulating material and which has the capability of efficient adherence to flexible wall structures as well as the capability of adhering to various metal and non-metal structures such as typically are used in the construction industry for commercial and residential structures.

Asbestos ericapsulation Asbestos has long been utilized as a construction material because of its heat and fire retarding characteristics. It has also been utilized as an efficient structure for sound absorption and for formation of ceiling surfaces of building structures because of its fairly lightweight character. It has been recently discovered, however, that asbestos fibres are carcinogenic and when deposited in the lungs of animals and humans, are difficult to expel. Moreover, asbestos has been determined to constitute a health hazard when utilized in building structures in such a manner that asbestos fibres and fibrils are liberated which can become entrained in the air and breathed by persons occupying the premises. Until recently, exposure to asbestos was generally considered an occupational health hazard for asbestos workers.However,- now it has been learned that an equally serious exposure problem exists that can occur in all types of buildings in which certain asbestos-containing materials have been used for fireproofing, insulation and decoration. Asbestos fibres can be released from these materials and tontaminate the building environment. Individuals who are then exposed to the asbestos could develop lung cancer or cancers of other parts of the body due to the carcinogenic character of the fibres. Unfortunately, detection of asbestos-related diseases is difficult because the latency period between exposure and appearance of the disease is sometimes as great as from twenty to forty years.

During the year 1 982 a requirement was published in the Federal Register of United States of America calling attention to a recently adopted Environmental Protection Agency regulation which required that public and private school facilities be visually inspected for friable materials.

According to this regulation, if friable material is located, it must be analysed for asbestos content and the results of the analysis must be posted in district administration offices and in faculty and custodial workrooms and lounges in the affected buildings. Schools in which friable asbestos containing material exists must post warnings about the health hazards of -asbestos and instructions about methods to be used by school employees to avoid or reduce exposure to asbestos. For purposes of this regulation, friable material is defined as any material applied onto ceilings, walls, structural members, piping, duct work and any other part of the building structure which, when dry, may be crumbled, pulverised or reduced to powder by hand pressure.Where large quantities of asbestos fibres are present in friable materials, it is virtually assured that a requirement will be made to reduce or eliminate such materials by constructure operations. It is desirable therefore to provide means for simply and efficiently rendering building structures safe when asbestos containing friable materials are determined to be present in building structures which are continuously occupied by humans. Such materials are widely utilized in school buildings and office buildings.

Sound absorption In school buildings and office structures as well as in many other commercial buildings and homes, many different materials are used for the purpose of sound absorption. For the most part, these materials take the form of flammable materials unless otherwise treated to provide a fireproof or fire retarding capability. In many cases, friable asbestos containing materials have been utilized for the purpose of sound absorption. These materials therefore are subject to the concern from the standpoint of asbestos contamination discussed above. It is desirable therefore to provide materials having the capability of efficient sound absorption and which also are capable of providing efficient fireproofing and asbestos encapsulation thereby to render most sound absorption materials both fireproof and environmentally safe from the standpoint of health.

The present invention seeks to provide a fireproofing adhesive material having efficient fibre penetration and encapsulation as well as being capable of rendering the fibre fireproof. More specifically, this invention concerns a fireproofing- adhesive material which may be efficiently combined with fibrous and pulverant materials toform a spray-on type insulation having efficient thermal insulating quality, as well as being of fireproof nature.

Briefly stated, the present invention is a liquid fireproofing adhesive composition comprising an aqueous suspension or emulsion-containing a major amount of an alkali metal silicate and minor amounts of a water repellent agent and a surfactant. Preferably the composition also contains a minor amount of a liquid stabilizer plasticizer compound and further preferably contains a minor amount of a malodour control agent. The akali metal referred to herein may be Ni, K, Li, Rb, or Sc; however, Na and K are preferred. The present emulsions are substantially stable and do not tend to separate or phase.

It is therefore a primary feature of the present invention to provide a fireproof adhesive material having the capability of utilisation with other fibrous or particulate materials to form a spray-on insulation having efficient fireproofing capability.

It is another feature of this invention to provide a novel fireproof adhesive material having sufficient flexibility for adhesion to the interior walls of most metal and nonmetal buildings thereby to provide efficient heat insulation characteristics as well as efficient fireproofing capability.

It is an extra further feature of the present invention to provide a novel fireproof adhesive material which has the capability of fibre encapsulation and which is capable of efficiently penetrating fibrous materials and developing fibre encapsulation, thus rendering the fibres thereof safe from the standpoint of potentially carcinogenic character.

Among the several features of this invention is contemplated the provision of a novel fireproof adhesive material which may be incorporated with other pulverant materials and sprayed onto building surfaces to provide efficient sound absorption as well as accomplish fire-proofing of the building surfaces.

It is also a feature of this invention to provide a novel fireproof adhesive material which will retard any flame spread when cooperatively assembled with other pulverant materials in the form of a spray-on coating.

It is also a feature of this invention to provide a novel fireproof adhesive material incorporating basically incompatible constituents which are assembled in such a manner as to yield a substantially inseparable liquid fireproof adhesive that may be simply and efficiently applied to provide for the fireproofing of the surfaces of buildings and other structures.

It is also an important feature of this invention to provide a novel method of manufacturing a fireproof adhesive material wherin basically incompatible constituents of the adhesive material are assembled in particular quantity in a particular order thereby to accomplish efficient development of a colloidal suspension that will remain substantially inseparable for extended periods of time.

It is also a feature of this invention to provide a novel fireproof adhesive material which may be efficiently assembled, is low in cost and reliable in use.

Briefly, the fireproof adhesive material of this invention incorporates a predetermined quantity of liquid alkali metal silicate, preferably sodium silicate, within which is mixed a quantity of surfactant/water solution sufficiently to render the fireproof adhesive material flexible, when cured, and to provide for emulsification in the liquid state thereof. The adhesive mixture also preferably includes a sufficient quantity of silicone water repellent to render the adhesive material durable, chemically resistant and water repellent, when cured. Further, the adhesive mixture, when applied, is in the form of a substantially inseparable liquid suspension in the uncured state and becomes cured to a hardened or solid form upon exposure to atmosphere thereby transforming from the liquid state to a solid flexible mass having efficient adhesion to most metal and nonmetal surfaces.The fireproof adhesive material may also incorporate a sufficient quantity of a liquid stabilizer plasticizer compound to enhance the flexibility of the adhesive, when cured.

The particular constituents of the fireproof adhesive material are mixed in accordance with a process wherein basically incompatible constituents are forced in assembly thereby to yield a substantially inseparable suspension which will remain in liquid form for substantial periods of time and which, upon being exposed to the atmosphere, will become cured within a relatively short period of time to form a resilient mass having efficient adhesion to most surfaces. The constituents are mixed in a powered mechanical mixer wherein the range of mixing speed is sufficiently high to prevent crystallization of the materials during assembly and is sufficiently low to prevent heat induced crystallization that would otherwise result in the destruction of the material for the purposes of an adhesive.The blades of the mixer turn sufficiently slowly that the mixture is assembled by means of a cutting or shearing activity rather than beating. The adhesive material may also incorporate a malodour control agent to ensure against the presence of undesirable odours.

The scope of the invention is defined by the appended claims; and how it can be carried into effect is hereinafter particularly described.

Although the present invention is not limited to the manufacture of the adhesive material hereof by means of a "batch" process where a particular quantity of fireproof adhesive material is manufactured, for purposes of simplicity, the present invention is discussed herein particularly as it relates to a batch manufacturing process. Further, the size of the particular batch set forth in the examples following is representative only of the particular dimension of a pilot manufacturing plant having the capability of manufacturing small batches of fireproofing adhesive material for test purposes. The respective percentages of the various constituents incorporated in the adhesive material will not vary significantly therefor even though a much larger batch process may be involved or a continuous manufacturing process may be involved.

The various constituents of the fireproof adhesive material are discussed by volume rather than by percentage as they relate to the particular batch volume being processed by the pilot plant.

As mentioned above, the various constituents of the fireproof adhesive material are basically incompatible. If assembled without any form of agitation or if agitated improperly, these materials will result in various composite forms including a complete or partial crystalline form or a form where certan constituents either float on top of other liquid constituents or settle to the bottom thereby resulting in stratification due to improper mixing. In order to assemble these constituents to form an inseparable liquid or a colloidal suspension, the materials must be forced into assembly in accordance with a process to be discussed hereinbelow.

After a number of preliminary tests were conducted it was determined that the character of agitation is critically important to proper manufacture of fireproof adhesive material. For this reason, a mixing machine was selected having a mixing vessel of sufficient dimension to contain approximately 2081.75 litres (457.93 gallons, 550 U.S. gallons) of liquid material, and an electric motor, belt driven liquid mixing mechanism having a rotary impeller type high shear blade assembly. It was determined through experimentation that a liquid cutting or shearing blade yields better constituent assembly capability as compared to a conventional mixing blade.

The incompatible materials of the fireproof adhesive material are more properly assembled by a cutting or shearing activity rather than by being beaten by the mechanical activity of a more conventional mixing blade. It was determined that a cutting type mixer blade would accomplish efficient suspension of the particles of the liquid materials without generating sufficient frictional heat on the materials to result in premature crystallization. It was also determined that mixing speeds must be conducted within a speed range of from about 500 to 3000 rpm, preferably about 800 rpm to about 2500 rpm. It was further determined that a range of from about 1 800 to 1 900 rpm is an optimum speed range for efficient cutting activity that yields desirable assembly of the various constituents involved in the fireproof adhesive material.

The principal constituent of the fireproof adhesive material is an alkali metal silicate, preferably sodium silicate, or water glass, which is incorporated in the mixture in a volumetric range in the batch sample produced of from about 1135.5 to about 1703.25 litres (about 249.78 to about 374.67 gallons, about 300 U.S. gallons to about 450 U.S. gallons).

The alkali metal silicates, known as the soluble silicates, are generally produced by fusing a high purity source of the appropriate alkali metal, e.g., soda ash and silica sand at high temperatures, e.g., 1 300' to 1500"C. Products in which the silica-to-alkali weight ratio is around 2:1 are water soluble, whereas those in which the ratio is above 2.5:1 must be dissolved by steam under pressure. Sodium silicate is by far the most common alkali metal silicate and is preferred, because it is readily obtainable and relatively inexpensive. The term alkali metal silicate is a generic term given to a family of chemicals composed of alkali metal oxide (AlkO2) and silica (six2) and usually, but not always, water.A broad range of alkali metal oxide to silica oxide may be used in the present composition, preferably from 1:1 to 1:6; however, alkali metal oxide to silica ratios of 1:2.5 to 1:4 are preferred. Silicates in which the alkali metal is less than about 1:2.5 are sticky and tacky, changing slowly fro liquid to solid with loss of water; whereas, those with a ratio above 1:4 are handleable materials in relative low solids content solutions. The alkali metal silicates are normally employed in water solutions with the solids content as concentrated as can be conveniently handled.Generally the alkali metal silicates will be employed in solution viscosities up to 400 centipoise at 20"C, preferably about 1 50 to 350 centipoise at 20"C. Thus, one of ordinary skill in the art can select the alkali metal silicate solution having the desired ratio of alkali to silica, solids content and viscosity for processing and end product properties (e.g., hardening rate, solids content and the like) within these ranges with a minimum of experimentation.

An optimum volume of sodium silicate for a particular batch volume of about 1517.785 litres (about 333.87 gallons, about 401 U.S. gallons) of the adhesive material was found to be in the order of 1400.45 litres, (308.06 gallons, 370 U.S. gallons). Further, the temperature range for the sodium silicate in preparation of the adhesive material was determined to be in the range of from about 10"C (50"F) to about 65.6"C (150"F). An optimum temperature was determined to be in the order of 37.8"C (100"F). At a temperature of 10"C (50"F) the sodium silicate liquid is of fairly viscous nature and is relatively reluctant to accept the other imcompatible constituents of the adhesive mixture. At temperatures above 37.8"C (150"F) the sodium silicate has a significant tendency to crystallization and either will not efficiently accept the other incompatible constituents in such manner as to form a colloidal suspension or will become crystallized to such sxtent that development of a liquid colloidal suspension become relatively impossible.

The liquid stabilizer plasticizer compound is preferably a diol, which is liquid at 0 C, has 2 to 4 carbon atoms and is soluble in water. Suitable diols include ethylene glycol (1,2-ethanediol), 1 ,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 2,3-butanediol.

The surfactant is preferably an anionic, nonionic or emphoteric surfactant, as those are generally known in the Anionic surface-active emulsifying agents, such as alkali soaps having the general formula, RCOOM, wherein RCOO represents a fatty acid containing from 3 to 25 carbon atoms (represented by R) and M is an alkali metal, such as sodium, potassium, lithium, and the like, can be used. For example, mixed fatty acids derived from tallow, cocoanut oil, palm oil, etc., are especially useful. Examples of suitable alkali soaps include the sodium and potassium salt of oleic acid, palmitic acid, stearic acid, linoleic acid, and the like.

Other anionic surfactants include an acid derived from other sources such as resin, for example, the sodium salts of abietic acid or isomers thereof.

Other anionic type surface-active agents which can be used include the aliphatic and alkyl aromatic sulphonates having the general formula:

wherein R is an aliphatic radical, aromatic radical (including alkaryl), or hydrogen atom and M is an alkali metal. Examples of suitable sulphonate type surfactants include the petroleum sulphonates, such as isopropyl-naphthalene sulphonate, sodium heptybiphenyl sulphonate, sodium salts of polymerized alkyl aryl sulphonic acids, and the like.

Typical of surface active agents containing sulphate of sulphonate groups are the salts of sulphated fatty alcohols, containing 8-18 carbon atoms, alkylbenzene-sulphonic acid containing 8-18 carbons atoms in the alkyl chains, or sulphated condensates of phenol, C8,8 alkyl-phenol, or C8,8 fatty alcohols with ethylene oxide. The cations of the salts are usually sodium, potassium, or ammonium ions.

The nonionic surfactants are compositions such as ethylene oxide or propylene oxide condensation products of compounds containing reactive hydrogen atoms. Suitable nonionic surfactants include compounds such as ethers havin the general formula R-(OCH2CH2)n-OH wherein R is an aromatic radical or an aliphatic radical containing up to 20 carbon atoms and n is an integer between 1 and 8.

An example of amphoteric surfactants is C-cetyl petaine.

A more complete list of useful anionic, nonionic and emphoteric surfactants can be found in the 1 964 publication, "Detergents and Emulsifiers", John W. McCutcheon, Inc., Morristown, New Jersey, and in Schwartz and Perry, "Surface Active Agents", New York Interscience, Inc., 1949.

Suitable silicone water repellents include the alkali metal salts of hydrocarbon substituted silantriol (sometimes called silonlates) of the general formula:

Alkali Metal I wherein R is a hydrocarbyl radical having 1 to 1 6 carbon atoms of alkyl, aryl, aralkyl, alkaryl, including non reactive substituents such as chlorine, bromine, fluorine, or iodine. The hydrocarbyl radicals which may be used include, for example, methyl, ethyl, docyl, phenyl, napthyl, biphenyl, benzyl, xylyl and the like. Formula I is believed to be the hydrous form which can be dried to (R SiO2) alkali metal.

Because the final composition of the present invention is an aqueous solution, the various components may all be admixed as aqueous solution.

The water serves both as the carrier for the components and the continuous phase for the emulsion which results from the present combination of components, and will generally comprise from about 40 to 70% by weight of the final (total) composition, more preferably about 55 to 65% by weight of the composition.Exclusive of water the components of the fireproofing composition are preferably present by weight in the following amounts: Alkali metal silicate 80 to 98% more preferably 90 to 95% Surfactnat 0.01 to 0.5% more preferably 0.03 to 1% Silicon water repellent 1 to 6% more preferably 2 to 3% Diol 1 to 10% more preferably 3 to 7% Maladour Control Agent 0.05 to 1 % more preferably 0.13 to 0.4% With the mixing vessel of the mixing apparatus containing approximately 1400.45 litres (308,06 gallons, 370 U.S. gallons) of sodium silicate, a sufficient quantity of a liquid stabilizer plasticizer compound is introduced while continuously agitating the sodium silicate with the mixing machine cutting blade operating at a rotational speed in the range of from 1800 to 1900 rpm.In one suitable form of the invention the liquid stabilizer plasticizer compound takes the form of ethylene glycol of which an amount in the range of from about 18.925 to about 75.7 litres (about 4.163 gallons to about 16.652 gallons, 5 U.S. gallons to about 10 U.S.

gallons) is mixed with the sodium silicate contained in the mixing vessel. Preferably an optimum quantity of ethylene glycol is about 37.85 litres (8.326 gallons), 10 U.S. gallons) which is quite slowly introduced into the sodium silicate liquid during continuous agitation. For example, the ethylene glycol is introduced at a rate not substantially exceeding 18.925 litres (4.163 gallons, 5 U.S. gallons) per minute. Introduction of the ethylene glycol, if too fast, will shock the sodium silicate liquid thereby resulting in immediate crystallization. It is necessary therefore to introduce the ethylene glycol into the agitating sodium silicate with such slowness that the sodium silicate remains liquid during total introduction of the ethylene glycol.The ethylene glycol provides the fireproof adhesive material with an antifreeze quality rendering it compatible for shipping, handling and storage in relatively low temperaure environments such as might occur during winter. Further, the ethylene glycol provides liquid stabilization and also functions as a plasticizer compound to enhance the flexibility of the cured adhesive after it has been applied.

A quantity of surfactant material is then dissolved in water, and this water/surfactant mixture is introduced into the agitating mixture within the mixer vessel. In order to prevent shocking of the sodium silicate which would result in immediate crystallization, the water/surfactant mixture is introduced at approximately the same or slower speed of introduction as described above in connection with the ethylene glycol.

After the ethylene glycol and surfactant/water solution have been completely introduced and dispersed within the mixture in the mixing vessel, a quantity of liquid silicone water repellent is introduced into the mixing vessel, its introduction also being slow as described above in connection with the ethylene glycol and surfactant/water constituents of the mixture. Ag , the viscosity of the mixture within the mixing vessel will determine the rate of silicone water repellent introduction. If the material is of fairly viscous nature the silicone water repellent must be introduced quite slowly.If the mixture is of normal viscosity which occurs at a temperature of about 37.8"C (100"F), the silicone water repellent may be introduced mote rapidly without shocking the mixture and causing immediate crystallization. To a batch of the volume set forth above, the volume of liquid silicone repellent will be in the order of from 37it5 to 75.7 litres (8.326 to 16.652 gallons, 10 to 20 U.S. gallons), the optimum volume thereof being in order of 56.775 litres (12.489 gallons, 15 U.S. gallons). After slow introduction of the silicone water repellent material is completed, agitation is continued for a sufficient period of time for the cutting blade of the mixing mechanism to establish a colloidal or inseparable mixture.After this has occurred, the mixing apparatus may be deenergized and the adhesive mixture within the mixing vessel may be transferred to drums, tanks and other storage vessels for storage and handling. When properly mixed the adhesive material will not become stratified due to settling and floating but rather will remain a homogeneous liquid consistency capable of being picked up by the pumps for handling or the venturis of adhesive spraying appartus for spray application to surfaces.

The silicone water repellent liquid may taken the form of sodium methyl silanolate solution which provides the adhesive mixture with excellent thermal and oxidative stability, water repellency, durability, chemical and corrosive resistance and good durability.

A waterproof fire resistant adhesive mixture manufactured in accordance with the above will typically be of malodourous character. To eliminate or minimize this malodourous character and to enhance further the flexibility of the resulting cured fireproof adhesive material, a quantity of a suitable deodorant material may be introduced during the mixing phase. An example of a suitable malodour control agent which also provides additional flexibility control is a water activated malodour control concentrate which is manufactured and sold under the trademark OXFORD AIR-O-SYN by Oxford Chemicals of Atlanta, Georgia, United States of America. To a batch of adhesive material such as set forth above water activitated malodour control concentrate in the order of from 1.8925 litres (2 U.S. quarts) to 5.204375 litres (5.5 U.S.

quarts) is typically introduced into the mixture, the optimum quanitity being in the order of 3.311875 litres (3;5 U.S. quarts). This malodour control concentrate will effectively render the resulting fireproof adhesive material substantially free of any objectionable odours. In addition to providing malodour control, the OXFORD AIR-O-SYN malodour control concentrate also enhances the flexibility of the resulting, cured fireproof adhesive material.

Following is a graphical representation of the low range, optimum and high range values for the various volumes of constituents, temperatures and mixing speeds which may be employed in the manufacture of fireproof adhesive material according to the present invention. Although specific materials are identified, it is not intended that the present invention be restricted to utilization of the specific materials and volumes set forth. Other suitable materials may be substituted for those set forth within the scope of the present invention.

Adhesive Constituent Low Range Optimum High Range 1. Liquid Sodium 1211.2 litres 1400.45 litres 1589.7 litres Silicate 320.0 I.S.gal 370.0 U.S.gal 420.0 U.S.gal 2 Mixing Temp. 10 C 37.8 65.6 C 50 F 100 F 150 F 3 Ethylene Glycol 18.925 litres 37.85 litres 75.7 litres (Regular) 5.0 U.S.gal 10.0 U.S.gal 20.0 U.S.gal 4. Surfactant-Ultra 226.796g 453.6g 907.2 Wet D.S. (Flake) 0.5 lb. 1.0 lb. 2.0 lb 5. Water 7.57 litres 18.925 litres 30.28 litres 2.0 U.S.gal 5.0 U.S.gal 8.0 U.S.gal 6. Malodour Control 1.8925 litres 3.311875 litres 5.204375 litres Agent 2.0 U.S.qt 3.5 U.S.qt 5.5 U.S.qt 7. Silicone Water 37.85 litres 56.775 litres 75.7 litres Repellent 10.0 U.S.gal 15.0 U.S.gal 20.0 U.S.gal 8.Mixing Speed 500 RPM 1800 to 3000 RPM 1900 RPM Because many of the particular constituents of the fireproof adhesive material may be variously obtained in various grades, more specific identification of the various constituents are as follows.

The sodium silicate most widely utilized is silicate of soda, grade 40, which is obtained from the Diamond Shamrock Corporation, 351 Phelps Court, P.O. Box 2300, Irving, Texas 75061, United States of America. This silicate of soda is soluble in water and is a colourless, turbid liquid with an odour of none to slightly soapy. This sodium silicate has a specific gravity of 1.30-1.71 at 20'C in comparison to water at a specific gravity of 1 at the same temperature.

The liquid sodium silicate material has a boiling point of from 101.11 C to 102.22"C (214'F-216?F). In the fireproof adhesive material, the sodium silicate functions as a fireproof bonding material and enhances the rapidly of setting after the material has been applied.

Additionally, it functions as a rust inhibitor, and provides resistance to vermin. It is also inorganic and nontoxic.

The sodium methyl silanolate solution may be of the type manufactured by Union Carbide Corporation, Silicones and Urethanes Intermediates, Old Ridgebury Road, Danbury, Connecticut 06817, United States of America, under the identifying symbol R-20. The physical form of this material is solution in water having a clear appearance and a water white colour. The apparent specific gravity of the material at 25/25on is 1.209. The active ingredient by weight is 30%. It has a viscosity at 25"C of 10 centipoises. The sodium methyl silanolate solution has excellent thermal and oxidative stability, is water repellent and provides the cured adhesive material with excellent durability. It is also chemical resistant and noncorrosive and may be efficiently sprayed from the standpoint of application.

The ethylene glycol constituent may be obtained from Dow Chemical Corporation, U.S.A., Midland, Michigan 48640, United States of America. This particular product may be identified as ethylene glycol (regular) and is a low density material in the form of a colourless, practically odourless liquid. The ethylene glycol has a boiling point of 197.271"C (387.1"F) and a vapour pressure of 0.1 2 MMHG at 25"C. It is soluble in water, completely miscible and has a specific gravity of 1.1155 ay 20/20"C. The ethylene glycol functions to lower the freezing point of the fireproof adhesive material and also functions as a stabilizer and plasticizer for the adhesive material to enhance the flexibility and adhesion thereof.

The surfactant constituent of the fireproof adhesive material may conveniently take the form of Ultra-Wet DS (flake) sodium alkylate sulphonate which is manufactured by Arco Chemical Company, Division of Atlantic Richfield Company, 1 500 Market Street, Philadelphia, Pennsylvania 19101, United States of America. The Ultra-Wet DS surfactant is a unique sodium alkylate sulphonate free flowing flake. It is used in aqueous media to provide or enhance surface activity, such as detergency, wetting, sudsing, dispersing and emulsifying. It is especially effective in hard water areas. This surfactant is completely soluble in water and is biodegradable.

The malodour control agent may conveniently take the form of water activated malodour control concentrate manufactured by Oxford Chemicals, P.O. Box 80202, Atlanta, Georgia 30366, United States of America, and sold under the trade name OXFORD AIR-O-SYN. This consituent is used in diluted mixture with water and is effective to render the odour characteristics of the resulting adhesive material from none to slightly soapy. The fireproof adhesive material will therefore have a reatively pleasant odour that will not disturb persons who are involved in spray application of the same.

From the standpoint of percentages by volume the sodium silicate constituent of the mixture is in the range of from about 90% to about 97%. The surfactant/water solution is in the range of from about 0.01% to about 0.1%. The silicone water repellent is in the range of from about 0.02% to about 0.2%. The liquid stabilizer plasticizer compound is in the range of from about 1.0% to about 5.0%. The silicon water repellent is in the range of from about 1.0% to about 4.0%.

The resulting fireproof adhesive material is of liquid form and has excellent adhesion to most metal and nonmetal surfaces. The element ingredients are largely inorganic and form upon solidification a permanent, flexible matrix which is nontoxic and highly stable. In addition, the temperature, light intensity and humidity likely to be encountered in occupied space should not contribute significantly to the deterioration or destabilization of the cured fireproof adhesive matrix. The fireproof adhesive material is highly resistant to acute thermal shock including open flame. The slight alteration in physical form of materials including encapsulated particles from insulation, plaster or wallboard due to physical or mechanical abuse or removal or thermal shock should not result in the significant release of small particles or fibres. The adsorption and absorption of the bonding matrix into asbestos fibres and fibrils results in entombment and encapsulation. Disruption of the encapsulation by mechanical abrasion, including sanding, should not result in disruption of large fibres into fibrils. Ingestion of encapsulated materials should not result in the bio-availability of fibrils because the solid matrix is not destroyed by digestive acids or enzymes. The bonding matrix will significantly reduce dust released by abrasion. Particles released by abrasion will be large for the most part and not appreciably absorbed by the pulmonary or gastrointestinal system of humans and animals. The fireproof adhesive material may be mixed during spray application with inert insulation particulate to form a protective, fireproof coating also having thermal insulation quality.A fireproof coating of this nature effectively provides fire protection, thermal insulation, sound absorption and, where required, asbestos fibre encapsulation.

In view of the foregoing, it is clear that the present invention is one well adapted to attain all of the objects, features and advantages hereinabove set forth, together with other advantages which will become obvious and inherent from a description of the invention itself. It will be understood that certain combinations and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the present invention.

As many possible embodiments may be made of this invention without departing from the scope thereof, it is to be understood that all matters hereinabove set forth are to be interpreted as illustrative and not in any limiting sense.

Claims (36)

1. A liquid fireproofing adhesive composition comprising an aqueous emulsion containing a major amount of an alkali metal silicate, a minor amount of a water repellent agent and a minor amount of a surfactant.

2. A composition accoridng to claim 1, wherein the alkali metal is Na.

3. A composition accordng to claim 1 or 2, wherein the water repellent agent is a silicone water repellent.

4. A fireproofing adhesive composition in liquid form, comprising a predetermined quantity of liquid sodium silicate; a quantity of surfactant/water solution sufficient to render the fireproof adhesive flexible, when cured, and to provide for emulsification in the liquid state thereof, and a sufficient quantity of silicone water repellent to render the adhesive durable, chemical resistant and water repellent, when cured, the adhesive composition being in the form of a substantially inseparable liquid suspension in the uncured state and being curable upon exposure to the atmosphere to a solid flexible mass.

5. A composition according to any preceding claim, wherein a minor amount of a liquid stabilizer plasticizer composition is present.

6. A composition according to claim 5 as appendant to claim 4, in which the liquid stabilizer plasticizer compound is present in a sufficient quantity to enhance the flexibility of the adhesive, when cured.

7. A composition according to claim 5 or 6, wherein liquid stabilizer plasticizer composition is a diol having 2 to 4 carbon atoms.

8. A composition according to claim 7, wherein the diol is ethylene glycol.

9. A composition according to claim 3 or 4, or any claim appendant to claim 3 or 4, wherein the silicone water repellent is an alkali metal salt of hydrocarbon substituted silantriol.

10. A composition according to claim 9, wherein the silicone water repellent comprises sodium methyl silanolate.

11. A composition according to any preceding claim, wherein the surfactant is nonionic or amphoteric.

1 2 A composition according to any of claims 1 to 10, wherein the surfactant is anionic.

1 3. A composition according to claim 12 wherein the surfactant is an aromatic sulphonate.

14. A composition according to claim 13, wherein the surfactant is an alkaryl sulphonate.

1 5. A composition according to any of claims 1 to 10, wherein the surfactant comprises sodium alkylate sulphonate dissolved in water.

16. A composition according to any preceding claim, wherein a minor amount of a malodour control agent is present.

1 7. A composition accordng to any preceding claim, wherein water comprises from 40 to 70% by weight of the total composition.

18. A composition according to claim 1, or any claim appendant to claim 1, containing, exclusive of water, from 80 to 98% by weight of alkali metal silicate, from 0.01 to 0.5% by weight of surfactant, from 1 to 6% by weight of water repellent and from 1 to 10% by weight of liquid stabilizer plasticizer which is a diol.

19. A composition according to claim 18 containing, exclusive of water, from 90 to 95% by weight of sodium silicate, from 0.03 to 1 % by weight of alkaryl sulphonate, from 2 to 3% by weight of silicone water repellent and from 3 to 7% by weight of diol having 2 to 4 carbon atoms.

20. A composition according to claim 4, or any claim appendant to claim 4, wherein the sodium silicate is present in the range of 90 to 97% by volume, the surfactant/water solution is present in the range of 0.01 to 0.1% by volume, and the silicone water repellent is present in the range of 0.02 to 0.2% by volume.

21. A composition accordin to claim 20 as appendent to claim 6, wherein the liquid stabilizer plasticizer compound is present in the range of 1.0 to 5.0% by volume.

22. A liquid fireproofing adhesive material capable of hardening upon exposure to air at ambient temperature to form a solid, resilient mass having good adhesion to metal and nonmetal surfaces, comprising the following constituents in the following proportions by volume or weight to form a batch volume of adhesive liquid based upon a volume of about 1517.785 litres (401 U.S. gallons), comprising: (a) 1400.45 litres (370.0 U.S. gallons) sodium silicate; (b) 37.85 litres (10.0 U.S. gallons) ethylene glycol; (c) 453.69 (1 pound) sodium alkylate sulphonate (flake) Surfactant; (d) 18.925 litres (5.0 U.S. gallons) water; (e) 3.311875 litres (3.5 U.S. quarts) malodour control agent; and (f) 56.775 litres (15.0 U.S. gallons) silicone water repellent.

23. A composition or material according to any preceding claim wherein the constituents are mixed in a temperature range of from 10"C (50"F) to 65.6"C (150"F).

24. A composition or material according to claim 23, wherein the mixing temperature is about 37.8"C (100"F).

25. A composition or material according to any preceding claim wherein the constituents are mixed with a shear type impeller blade drive at a rotational speed of from 500 to 3000 rpm.

26. A composition or material according to claim 25, wherein the rotational speed is in the range of 1800 to 1900 rpm.

27. A liquid fireproofing adhesive composition substantially as hereinbefore particularly described.

28. A process for the manufacture of fireproofing adhesive material of liquid form, comprising: (a) loading a mixing system having a mixing vessel and a motorized liquid agitating mechanism with a predetermined quantity of liquid sodium silicate; (b) initiating agitation of the liquid sodium silicate with the motorized liquid agitating mechanism; (c) slowly introducing a quantity of liquid stabilizer plasticizer into the mixing vessel while continuously agitating the liquid mixture; (d) slowly introducing a mixture of a quantity of surfactant and a quantity of water into the mixing vessel while continuously agitating the mixture; (e) slowly introducing a quantity of silicone water repellent into the mixing vessel; and (g) continuing mixing of the mixture in the mixing vessel for a sufficient period of time to develop a substantially inseparable liquid mixture.

29. A process according to claim 28 wherein the mixture is assembled in a temperature range of from 10 C (50 F) to 65.6"C (150"F).

30. A process according to claim 29, wherein the mixing temperature is about 37.8"C (100'F).

31. A process according to claim 28, 29 or 30, wherein the mixture is assembled with a shear type impeller blade rotatably driven at a rotational speed in the range of from 500 to 3000 rpm.

32. A process according to claim 31, wherein the rotational speed is in the range of 1800 to 1 900 rpm.

33. A process according to claim 28, 29, 30, 31 or 32, wherein the liquid stabilizer plasticizer is ethylene glycol.

34. A process according to any of claims 28 to 33, wherein the surfactant comprises sodium alkylate sulphonate (flake) surfactant.

35. A process according to any of claims 28 to 34, including introducing a quantity of malodour control agent into the mixture before the step of continuing mixing.

36. A process for the manufacture of fireproofing adhesive material of liquid form, substantially as hereinbefore particularly described.