NZ208902A

NZ208902A - Hydrophobic composite; granular material coated with polyurethane and hydrophobic colloidal oxide

Info

Publication number: NZ208902A
Application number: NZ208902A
Authority: NZ
Inventors: C E Craig
Original assignee: Craig Research Ltd
Priority date: 1983-07-14
Filing date: 1984-07-13
Publication date: 1987-07-31
Also published as: AR241228A1; IT1176391B; KR910000985B1; IT8421907A0; KR850001352A; GR81442B; IT8421907A1; ZA845481B

Description

<div class="application article clearfix" id="description"> New Zealand Paient Spedficaiion for Paient Number £08902 20890 No.: Date: Priority Date!a;: . AW- ~ Complete Specification Piled: 1_aH Class: ccqn5./.i 8,.^a.; aC&B.«k . 0046.15/04. Publication Date: ....?. J. .4WL J9j8Z> ... P.O. Journal. No: ... HQ E^r NEw ZEALAND PATENTS ACT, i953 HYrmrtn "^ErESPECIFICATION hydrophobic composite m£thnn • I£IH0D a,VO composition Xk '■ CRAIG MSHMCH m a ">e laws of Canada, of "P""10" organlzed under »««,» Columbia, Ca„ada QUee"SV°°d ^ Victor,., hereby declare the inventi , 6 lnventl°n for whichXTC/ ■'■'frBO -:--vr;:Er::r=~ iowmg statement:- - 1 - followed by i; m -la- 20890 2 Vj HYDROPHOBIC COMPOSITE, METHOD AND COMPOSITION BACKGROUND OF THE INVENTION The present invention relates to a method for making hydrophobic composites, the resulting composites, and a 5 coating composition containing same. More particularly, the present invention is directed to improved hydrophobic composite aggregates prepared by physically bonding a hydrophobic colloidal oxide to the individual aggregate particles, such as sand, gravel or slag, to provide a 10 product which is useful in various waterproofing applications and in cleaning up oil spills. A number of water-repellent composite materials composed of various absorbent substrates coated with organ-silicon compositions have been proposed for use in removing 15 oil or oil film from water contaminated therewith. One such material is disclosed in Tully et al., U.S. Patent No. 3,562,153, entitled "Oil Absorbent Compositions". The oil absorbent compositions of the Tully et al. patent are obtained by treating a liquid absorbent material, which may 20 be particulate, granular or fibrous in nature, with a colloidal metal or metalloid oxide which is chemically bonded to an organo-si1 icon compound to render the metal or metalloid oxide hydrophobic. The hydrophobic oxide-treated absorbent composition is contacted with the oil-contaminated 25 water and selectively removes the oil therefrom. The oil absorbent composition of Tully et al. is purported to have excellent water repellency, thus enabling it to maintain its oil absorbent efficiency for long periods of immersion in wa ter. '' % */, <■? »• v a o V I • . 20890 -2- SUMMARY OF THE INVENTION It has now been discovered, in accordance with the present invention, thaL hydrophobic composites having superior water repellency are obtainable by depositing on a V 5 core material an adherent first coat which comprises a film- forming polyurethane and asphalt, as an optional additive, and applying to the thus coated core material a second coat comprising a hydrophobic colloidal oxide of an element selected from the group consisting of silicon, titanium, 10 aluminum, zirconium, vanadium, chromium, iron or mixtures thereof. Hydrophobic composites prepared in this manner not only prevent water from adhering to the surfaces of the individual composite particles, but also from entering Lhe interstitial spaces of the aggregates of the composites. 15 It is believed that Lhe hydrophobic composites prepared in accordance with Lhis invention provide more durable waLer repellency than is obtainable from materials of Lhis kind heretofore available. Like the oil absorbent compositions described in Lhe 20 aforementioned Tully et al. patent, Lhe hydrophobic composites of Lhe present invenLion have uLiliLy in cleaning up oil spills, and may be applied Lo oil spills on waLer, on land, e.g., beaches, or on paved surfaces, 'w Moreover, the hydrophobic composites described herein 25 are especially useful in numerous waterproofing applications. They may be used alone as a waterproofing agent in building and pavement construction, for example, as a fill or bed maLerial under concreLe slabs or as a wall coating, both below and above ground, or as a gravel fill or ballast for 30 road beds or sidewalks. The composiLes may also be used as a substitute for common aggregate in asphalt roofing or -3- 208902 shingles, or in built-up roofing. In such applications, the hydrophobic composites are effective in preventing water penetration and resulting damage caused by freeze/thaw cycles as well as dimensional changes due to wetting and 5 drying. The hydrophobic composites of the present invention also have utility as a Lop coat on paved surfaces, such as asphalL or concreLe road surfaces or bridge decking, providing an exLremely water-tight finish which substantially reduces freeze/thaw damage, and which is unaffected by salt 10 compositions normally used for ice removal. In addiLion, Lhese hydrophobic composites may be applied Lo painted surfaces to provide a durable, waterproof finish over wood, •wr'1' metal, concrete, stone, brick, and certain synthetic substrates. 15 The hydrophobic composites of the present invention may also be blended with suiLable binding agents to provide a coating composition having excellent water repellency. DETAILED DESCRIPTION OF THE INVENTION A wide variety of inorganic or organic substances may 20 be used as the core material of the hydrophobic composite. The core material may be either solid or porous and includes sand, gravel, mine tailings, coal ash, natural rock, smelter slag, diatomaceous earth, crushed charcoal, sawdust, mica, wood chips, nut shells, and Lhe like. Inorganic materials 25 are favored from the standpoint of cost and availability. Particularly satisfactory composites have been obtained using inorganic siliceous subsLances such as sand, gravel or slag. Sources of these materials are conveniently available ^ ^ world wide. 30 The physical form of the core maLerial may vary, wiLh particulate or granular materials having a particle size between 25.0 millimeters (1 inch) and 125 microns (1/200 20890 -4- inch) being preferred. Particle sizes above 25.0 millimeters Lend to be difficulL Lo coat uniformly wiLh Lhe coaLings applied in pracLicing Lhis invenLion. ParLicle sizes smaller than 125 microns Lend Lo require excessive 5 amounLs of Lhe coaLings, making Lhe preparaLion uneconomical. Core materials in the preferred particle size range are easily obtained using standard sizing techniques. The core material should contain no more than 17» by weight of moisture. This degree of dryness may be achieved 10 by air drying or convenLional heating meLhods. Higher levels of moisture inLerfere wiLh sizing of Lhe core mate-^ rials and prevenL uniform coaLing of the core material surfaces. As mentioned above, the adherent firsL coaL which is 15 deposited on the core material serves to anchor Lhe subsequenLly applied hydrophobic ouLer coaL. The firsL coat comprises a film-forming polyurethane, alone, or in combination with asphalL, Lhe laLLer providing an increase in Lhe anchoring quality of Lhe first coat over a longer period of 20 time and an increased aLLracLion for oil and oil relaLed producLs. Any of Lhe film-forming polyurethanes commonly employed in Lhe field of coaLings may be used in Lhe pracLice of the present invention. Included in this category are the well-known Lwo-componenL and one-component 25 polyureLhane coating sysLems. The Lwo-componenL sysLems are formed by Lhe reaction of an aliphaLic or aromaLic isocya-naLe with a hydroxy1-bearing compound, such as polyfunc-tional polyesters based on adipic acid, phLhalic anhydride, ethylene glycol and Lrimethylolpropane, for example. 30 RepresenLaLive of Lhe one-componenL polyureLhane coaLing sysLems Lhat may be employed as Lhe firsL coaL are Lhose derived from sLable isocyanaLe-LerminaLed prepolymers formed from an aliphaLic or aromaLic isocyanaLe and polyfuncLional polyether or polyesLer. These one component systems are 35 commonly referred to as "moisture cured" polyurethane \ ■ ■ ••■••.VH 20830 -5- coatings because drying results from the reaction of the free-isocyanate groups of Lhe prepolymer with water or atmospheric moisture. AnoLher one-component polymer coaLing which may be used in the preparation of Lhe hydrophobic 5 composites is the "urethane oil" or "uralkyd", which is Lhe reacLion product of a diisocyanate with a hydroxyl-conLaining drying oil derivative, e.g., LhaL produced by alcoholysis of an unsaLuraLed glyceride wiLh a polyol, such as LrimeLhylolpropane. 10 A commercial polyureLhane composiLion sold under Lhe name "UreLhane Clear 66 High Gloss" by C.I.L. Paints, Inc., Montreal, Canada, has been found to produce a strong bond between the core material and the hydrophobic second coaL. When asphalt is included in Lhe adhesive firsL coaL, iL 15 may be presenL in an amounL up Lo Lhree hundred percenL (300%) by weighL of the film-forming polyureLhane, which is an amount up to about 7570 by weighL of Lhe firsL coaL. The Lerm "asphalt" as used herein refers Lo a dark brown Lo black cemenLiLious maLerial in which the predominate 20 consLituenLs are bitumens LhaL occur in naLure or are obLained in peLroleum processing, Lhe laLLer being preferred, primarily because of iLs greaLer availabiliLy. The asphalL componenL of Lhe adherenL firsL coaL may be eiLher solid, semi-solid or liquid, so long as iL forms a 25 homogeneous composiLion wiLh Lhe volaLile solvenL used Lo deposiL Lhe firsL coaL on Lhe core maLerial. The classes of liquid asphalLs known as rapid-seLLing emulsions and cuL-backs are especially suiLed Lo the process of Lhe presenL invenLion due Lo Lheir ease of handling. Such asphalLs are 30 commonly used as seal coaLs on paved surfaces. ParLiculary saLisfacLory firsL coaLs have been obLained using a t ^ commercially available asphalt sealer sold under Lhe name "Black Topper Driveway Resurfacer" by Tone CrafL LLd., ToronLo, Canada. 35 In general, Lhe adherenL firsL coaL consLiLuLes from abouL 0.025% to about 1.00% by weight of the finished -6- 208902 composite, depending upon the particle size and surface nature of the core material which determine the total surface area required to be coated. The adherent first coat is easily applied to the core materials by dissolving the film-forming polyureLhane and asphalt, if desired, in a volatile solvent to form a homogeneous coaLing composiLion, conLacting the core materials with the coating composition, and removing the volatile solvent from Lhe coating composition, thereby to deposit the adherenL firsL coat uniformily over the surfaces of the core materials. The volatile solvenL is conveniently removed by evaporaLive heating. Since the volatile solvent merely functions as a vehicle for depositing the first coat on the core materials, virtually any volatile solvenL in which the components of the first coat are soluble may be used. Good resulLs have been obtained using petroleum distillates, such as mineral spirits or paint thinner. Such solvenLs have a boiling poinL between about 200° and 400°F. (93.3 - 204.4°C) and are readily evaporated from the mixture of core materials and coaLing composiLion by convenLional heating means. The hydrophobic second coat used in Lhe pracLice of this invention is a hydrophobic colloidal oxide of an element selected from Lhe group of silicon, LiLanium, aluminum, zirconium, vanadium, chromium, iron or mixLures thereof. In general, colloidal oxides having an average particle size of less than 1 micron are preferred, and 0.5 micron or less are especially preferred. Oxides of higher average particle size should be avoided because their reduced organic surface area would in turn reduce Lhe number of hydrophobic siloxane groups aLLached Lo Lheir surfaces; lower particle size oxides are undesirable because of increased cost of production. The oxide is rendered hydrophobic via a chemisorpLion reacLion wiLh cerLain well- -7- 20890 known organo-si1icons, which have long been used for this purpose. The oxide surface must have sufficient reactive hydroxyl-groups Lo undergo reaction with the organo-silicon compound. In general, at least about 0.25 milliequivalents 5 per gram of hydroxy1-groups is required. Various organo-silicon compounds bearing reactive functional moieLies will O undergo reaction with the surface hydroxy1-groups on the oxides to chemically bond Lhe organo-silicon compound to the oxide. Specific examples of such compounds include organo-10 halosilanes such as (CH3)3SiCl, (CH3)2SiBr2» (CH3>2SiCl2> (C4H9) 3SiCl or organosilylamines such as (CH3)3Si(CH2)3NH Q (CH2)2NH2, and (CH3O)2(CH3)SiCH2CH(CH3)CH2NHCH2CH2NH2, among others. The details of the processes available for the chemi-15 sorption reaction between colloidal oxides and organo-silicons are wel1-documented in both Lhe paLenL and scienLific literature and are familiar to those skilled in the art. Colloidal silicas are the colloidal oxides of choice 20 because of availability and reasonable prices. A hydrophobic fumed silica made by Tulco Inc., Talbot Mills Industrial Park, North Billerica, Mass., and sold under Lhe name "Tullanox 500" has been found to provide an excellenL hydrophobic second coaL. This product is derived from fumed 25 silica (99.87« Si02), Lhe individual parLicles of which have c chemically bonded Lo Lheir surfaces hydrophobic LrimeLhyl- siloxyl groups of Lhe formula (CH3)SiO--. "Tullanox 500" (generally having parLicle diameLers of 0.5 microns or less) has an exLremely large surface area, enabling iL Lo 30 imparL superior water-repellency when applied in relatively 1 j low concentrations Lo Lhe core materials having Lhe adherenL first coaL Lbereon. As used herein, Lhe Lerm "fumed silica" refers Lo a colloidal form of silica made by combustion of silicon tetrachloride in hydrogen-oxygen furnaces. 20890 2 -8- In general, Lhe hydrophobic second coaL consLiLuLes from abouL 0.025% to abouL 1.00% by weighL of Lhe finished composiLe, depending upon Lhe parLicle size and surface nature of Lhe core maLerial which deLermine Lhe LoLal 5 surface area required Lo be coaLed. In coaLing applications in which Lhe hydrophobic composites are exposed to the elements or to conLinuous wear over long periods of Lime, iL is avantageous Lo incorporaLe a powdered abrasive in an amounL up Lo abouL 0.25% by weighL 10 of Lhe finished composiLe. A suitable abrasive for this purpose is powdered corundum (AI2O3) of a parLicle size of less Lhan 50 microns (1/500 inch). The general procedure for preparing Lhe hydrophobic composiLes of Lhe presenL invenLion will now be described. 15 The core maLerial, which, as indicaLed above, is preferably a parLiculaLe or granular material such as sand, gravel or slag, is dried to a moisture content of less Lhan 1% by weighL and sized as required for the intended end use of the composite. Next, Lhe core material is mixed wiLh a 20 coaLing composiLion comprising, by weighL, from abouL 5"L Lo about 20%, preferably from abouL 10% Lo abouL 20%, of a film-forming polyureLhane, from 0% to about 20%, preferably from about 5% to abouL 10%, of asphalL, and from abouL 60% to about 90%, preferably from about 70% to abouL 90%, of a 25volaLile solvent, e.g., a peLroleutn distillate, in which Lhe film-forming polyureLhane and asphalL are soluble. The amounL of coating composition used to deposiL Lhe adherenL first coat may be up to about 1.0% by weighL of the dry core maLerial. The required amounL of Lhe coaLing composiLion 30 will vary depending on Lhe parLicle size and naLure of Lhe core material. For example, considerably less Lhan 1.07o of Lhe coaLing composiLion is needed for relatively coarse core maLerial, i.e., maLerial having a parLicle size larger than 750 microns (1/32 inch). The use of coaLing composiLion in 20890 -9- an excess of 1.0% by weight of the dried core material is unnecessary unless the core material is open-celled, requiring an increase in coating composiLion to insure coverage of Lhe entire surface area. Mixing is conveniently 5 carried out by tumbling Lhe core maLerial and coating composiLion LogeLher in a convenLional Lumbling apparaLus such as a drum mixer. The mixture is then heated to a temperature of between 200°F and 400°F (93.3° - 204.4°C) to effect substantially complete vaporization of the 10 solvenL, leaving Lhe core maLerial uniformly covered wiLh the adherent first coat. The core material with Lhe adhesive first coat thereon is contacted with the hydrophobic colloidal oxide and powdered abrasive (depending on Lhe inLended end use) which become bonded to Lhe core maLerial 15 by the adherent first coat. Here again, Lumbling is Lhe meLhod of choice for applying Lhe hydrophobic second coat. The resulting hydrophobic composites are cooled to ambient temperature and packaged, if desired. It is esLimaLed LhaL the processing time for production of the hydrophobic 20 composite by Lhe above procedure on a commercial scale, from drying through packaging, would take from about 30 to about 90 minutes. The hydrophobic composite produced by the above procedure is non-toxic, non-dusting and as free-flowing as Lhe 25 uncoated sLarting core material. When immersed in water, an aggregate of the hydrophobic composites Lakes on a puLLy-like consistency, but upon removal from Lhe water is dry and becomes free-f2owing once again. The process of Lhe present invention produces no 30 chemical change in Lhe sLarLing core material. The changes that resulL are sLricLly physical. Thus, Lhe coaLing composiLion weLs ouL Lhe surfaces of Lhe core maLerials and, on heaLing, Lhe volaLile solvenL component of the coating composition evaporates, deposiLing a uniform adherenL firsL 35 coat on the core materials. Upon mixing of Lhe hydrophobic colloidal oxide and abrasive (if used) wiLh Lhe core \ I 20890 -10- material having Lhe firsL coaL Lhereon, Lhe former becomes firmly bonded Lo Lhe laLLer. The hydrophobic composiLes of Lhe presenL invenLion may be applied Lo a subsLraLe Lo be coaLed LherewiLh in any 5 desired manner, such as by spraying, Lrowelling or flowing. The raLe of applicaLion of hydropobic composiLe will vary in Lhickness according to use and function. When the hydrophobic composites are employed as a Lop coat on paved surfaces, such as asphalt or concrete, a flood 10 coat of asphalt sealer should first be applied over the surface, inunediaLely after which a heavy coat of the hydrophobic composites is sprayed over and rolled inLo the asphalt sealer, providing an extremely watertight top coat. The same top coating technique may be used in pot hole 15 repairs in roadways. Lining of Lhe poL hole wiLh Lhe hydrophobic composites also prevents water peneLraLion from underneath the roadbase. A Lop coaL of the hydrophobic composites may be applied in similar fashion following conventional spray coaLing of traffic markings on road 20 surfaces, to provide a water-repellenL, durable finish with improved visibility in the rain and at night. The hydrophobic composiLes may also be applied over a coaL of adherent material, such as asphalL or paint, to various metal substrates Lo prevenL oxidaLion of Lhe meLal and are 25 especially useful in rust prevention. Also within Lhe scope of Lhe presenL invention are water-repellent coaLing composiLions comprising an aggregaLe of Lhe hydrophobic composiLes described herein and a liquid binding agenL. SuiLable liquid binding agenLs are Lhe same 30 asphalLs as used in Lhe adhesive firsL coat of Lhe hydrophobic composiLes, or any asphalts or coal tars used in conventional paving or roofing operations, or any liquid binding agent, such as paint, varnish, lacquer, liquid plastic or adhesive, which will accept and retain the 35 hydrophobic composiLes. The amount of liquid binding agent 20890 2 -11- o used in preparing the composiLion will generally range from 5% Lo 10% by weighL, depending on Lhe average parLicle size of Lhe aggregaLe. The smaller Lhe average particle size of the aggregaLe, the lower the amount of binding agent 5 required. The coating composiLion is applied by spraying, brushing or flooding the liquid binder over the maLerial to be coated (metal, wood, concrete, asphalL, etc.). followed by application of the hydrophobic composite in an even layer onto the binder by spraying or flooding, followed by 10 conventional rolling or oLher pressure applicaLion as required Lo insure peneLraLion of Lhe composiLe inLo Lhe binder. The following examples further describe the manner and process of making and using the invention and set forth Lhe 15 besL mode conLemplated for carrying out the invention, buL are noL to be construed as limiLing Lhe invenLion. EXAMPLE 1 Ordinary sand obtained from a commercial sand and gravel pit in Victoria, B.C., Canada, was dried by heating 20 in an electric furnace to a moisLure conLent of less than 170 by weight. The sand was sized using a Tyler screen to remove particles in excess of 1.5 millimeLers (1/16 inch) and the remaining sand was collected. One thousand (1,000) grams of Lhe collected sand was placed in a closed meLal Q 25 cylinder wiLh five (5) grams of coaLing composiLion conLaining 1/2 gram of film-forming polyureLhane (Urethane Clear 66 High Gloss), 1/2 gram of asphalt (Black Topper Driveway Resurfacer) and four (4) grams of a volatile petroleum distilllaLe ("Shell Sol", available from Shell 30 Canada LimiLed, Don Mills, OnLario, Canada). The amount of the coaLing composiLion was 0.57o by weighL of the dry sand. The sand and coating composition were tumbled together in 208902 -12- ; Lhe closed metal conLainer for five (5) minuLes. Thereafter, the mixture of sand and coaLing composiLion was heated in the tumbling apparatus to a LemperaLure of about 200°F. to evaporaLe Lhe solvent, thereby depositing a uniform 5 adherenL coaLing of Lhe polyureLhane and asphalt on the individual sand particles. Evaporation of the solvent required about 30 minutes. A mixture of one (1) gram of hydrophobic fumed silica (Tullanox 500) and one (1) gram of powdered corundum was then added to the metal cylinder and 10 mixed with Lhe coaLed sand parLicles Lo apply Lhereto a hydrophobic outer coat. The resulting hydrophobic sand was then cooled to room temperature. The following example sets forth the resulLs of a Lest carried out Lo evaluate the durability of Lhe hydrophobic 15 composites of the present invention. EXAMPLE 2 The testing of any given water-repellent granular maLerial by immersing in waLer and deLermining the Lime required for Lhe material to absorb a measurable amounL of 20 waLer can be quiLe Lime consuming. This is parLicularly Lrue of highly waLer-repellenL maLerials which are able Lo resist water absorption for many months, or even years. The test described in Lhis example was designed for evaluaLing the water-repellency of materials in Lhe laLter category by 25 accelerating Lhe raLe of water absorpLion so LhaL absorpLion occurs within a reasonable time frame. In carrying ouL Lhis LesL, advanLage is Laken of the known tendency of detergenLs to destroy Lhe waLer-repellency of hydrophobic subsLances and rapidly increase the rate of water absorption of such 30 subsLances. \ . X I ....... -■ ■ 20890 * -13- A mild detergent solution was prepared comprising, by weight, 7.5% of a common household detergent ("Sunlight Detergent", available from Lever Detergents, Limited, Toronto, Canada) and 92.5% distilled water. The solution 5 was well shaken and allowed to stand for at least 24 hours. Three separate test samples were made up using ordinary sand dried to a moisture content of less Lhan 1% and having a particle size between 1500 microns (1/16 inch) and 125 microns (1/200 inch). Each sample weighed one hundred (100) 10 grams. Sample A comprised untreaLed sand and was used as a control. Sample B was treated by mixing it in Lhe dry state with 0.10% by weighL of hydrophobic fumed silica (Tullanox 500) in Lhe manner described in Lhe aforemenLined Tully et al. patent. Sample C, by processing in accordance with this 15 invention, was provided (after solvenL evaporaLion) with 0.10% by weight of an adherent first coat made up of a 50:50 blend of Urethane Clear 66 High Gloss and Black Topper Driveway Resurfacer and a 0.10% by weight outer coat of hydrophobic fumed silica (also Tullanox 500). Twenty (20) 20 grams of each sample was placed in a clear plastic vial approximately 1-1/4 inches (3.2 cm) in diameter and 2-1/2 inches (6.4 cm) in height and leveled by shaking. A concave indentation approximately 3/4 of an inch (2 cm) in diameter was made in Lhe upper surface of the material in each vial. 25 One (1) ml. of the detergenL soluLion was drawn inLo an eye dropper and, wiLh Lhe eye dropper held wiLhin 1/8 inch (0.3 cm) of Lhe upper surface of the sample, the detergent soluLion was carefully dispensed inLo Lhe indenLaLion. The time required for the deLergenL soluLion to be 30 completely absorbed in Lhe indenLation of each sample was then accuraLely measured. AbsorpLion was deemed Lo be compleLe when reflected light from Lhe soluLion in Lhe indentation was no longer visible. It is considered safe to V I n, ZV890 -14. assume LhaL each minuLe of Lime required for complete absorpLion of Lhe detergent solution roughly corresponds to a minimum of 100 days for the complete absorpLion of ordinary waLer, i.e., conLaining no detergent. This rough 5 Lime equivalency is based on long-term LesLing of 100 grams of Sample B material, Lreated wiLh only 0.01/!, (rather Lhan 0.10%) by weighL of Tullanox 500, which sample was kept submerged in four (4) inches (10 cm) of ordinary water and showed no indication of waLer absorpLion after 150 days (a 10 portion removed from under the water being dry and free flowing), but which had absorbed 27* of its own weight of water after 200 days of submersion. A reLained sample of the same material, noL submerged in water, was LesLed as above wiLh Lhe deLergenL soluLion and had an average 15 absorpLion time of 1.2 minuLes on five (5) samples LesLed. The following Lable seLs forth the average resulLs of five (5) tesLs conducted, as described on page 13, on each of Samples A, B, and C. Sample AbsorpLion Time (in min.) AbsorpLion Time 20 for DeLergenL SoluLion (in days) For Ordinary WaLer A less than 1/60 minute* less Lhan 1/60 minuLe* B approximaLely 15 minuLes aL leasL 1500 days C approximaLely 75 minuLes aL least 7500 days 25 * Absorption occurred immediately These LesL resulLs indicaLe LhaL Lhe hydrophobic composiLe prepared in accordance with the presenL invenLion, </div>

Claims

<div class="application article clearfix printTableText" id="claims"> T © r* 2,08902 -15- i.e., wherein the hydrophobic outer coat is bonded to the core material by an adherent intermediate coat, provides more durable water repellency than a similar hydrophobic material without an adherent intermediate coat. 5 The core material employed in the foregoing examples may be replaced, if desired, by gravel, mine tailings, coal ash, natural rock, smelter slag, diatomaceous earth, crushed charcoal, sawdust, mica, wood chips, or nut shells. Similarly, the components of the coating composition used to 10 apply the adherent first coat may be replaced by equivalent materials. For instance, most fast-drying liquid plastics may be used as a substitute for the Urethane Clear 66 High Gloss, most cut-back and emulsified liquid asphalts or coal tars may be used as a substitute for the Black Topper Driveway Resurfacer, and most paint thinners or mineral spirits may be used as a substitute for the Shell Sol solvent. In addiLion, hydrophobic colloidal titania, alumina, zirconia, vanadia, chromia, or iron oxide may be used instead of hydrophobic fumed silica. 20 it is not intended to limit the present invention to particular embodiments described and exemplified in the foregoing specification, but various modifications may be made therein and thereto without departing from the scope and spirit of the invention as set forth in the following 25 claims. Q -16- WKAT^V.*" I *3:

1. A hydrophobic composiLe comprising a core maLerial selecLed from Lhe group consisLing of parLiculaLe and granular material having Lhereon an adherent first coat 5 comprising a film-forming polyureLhane, and a second coaL which is bonded Lo said core maLerial by said adherenL firsL coat, said second coaL comprising a hydrophobic colloidal oxide of an element selecLed from the group consisting of silicon, titanium, aluminum, zirconium, vanadium, chromium, 10 iron and mixtures thereof.

2. The hydrophobic composite of claim 1, wherein said first coat includes asphalt in an amounL up Lo 50% by weighL of said first coat.

3. The hydrophobic composiLe of claim 2, wherein said 15 adherenL firsL coat and said second coat each consLiLuLe from 0.025% to 1.00% by weighL of said hydro phobic composiLe. A.

The hydrophobic composiLe of claim 3, wherein said second coaL consisLs essenLially of hydrophobic fumed silica 20 and an amounL of corundum up to 100% by weighL of said fumed silica.

5. The hydrophobic composiLe of claim 4, wherein said core maLerial is a siliceous substance.

6. The hydrophobic composiLe of claim 5, wherein said 25 siliceous subsLance is selecLed from Lhe group consisLing of sand, gravel and slag. i V - 9 JUJVJ987 J -17-

7. An aggregate consisting essentially of Lhe hydrophobic composite of claim 6.

8. The hydrophobic composite of claim 1, wherein said core material is selecLed from Lhe group consisting 5 of sand, gravel, mine tailings, coal ash, naLural rock, smelter slag, diaLomaceous earth, crushed charcoal, sawdust, mica, wood chips and nut shells.

9. The hydrophobic composite of claim 1, wherein said material has a particle size in the range of 25 milli- 10 meters to 125 microns.

10. The hydrophobic composite of claim 1, wherein said second coat includes a powdered abrasive material.

11. The hydrophobic composite of claim 10, wherein said powdered abrasive material comprises powdered corundum. 15

12. The hydrophobic composite of claim 10, wherein the particle size of said powdered abrasive material is less than 50 microns.

13. A method for producing hydrophobic composiLes which comprises Lhe steps of: 20 a) providing core materials selected from the group consisting of particulate and granular material in a predetermined size range; b) admixing said core materials with a coating composition comprising, by weighL, from 10% Lo 25 20% of a film-forming polyureLhane, from 0% to 10% of asphalt and from 70% to 90% of a volaLile solvent in which said film-forming polyurethane and asphalt 208902 -18- are soluble, and removing substantially all of said solvent from the mixture of core materials and coating composition, thereby to deposit on said core materials an adherent first coat; and 5 c) applying to the core materials having said adherent first coat thereon, a second coat which is bonded to said core material by said adherent first coat, said second coat comprising a hydrophobic colloidal oxide of an element selected form the group consisting of silicon, titanium, 10 aluminum, zirconium, vanadium, chromium, iron and mixtures thereof thereby to provide a hydrophobic composite.

14. The method of claim 13, wherein the coating composition of step (b) comprises an amount, excluding the volatile solvent, of up to 0.5% by weight of the core materials.

15. The method of claim 14, wherein the solvent component of said coating composition used in applying said adherent first coat is removed by evaporative heating. 20

16. The method of claim 15, wherein said core material is sand and said second coat is hydrophobic fumed silica.

17. The method of claim 15, wherein said second coat is applied to the core materials having said adherent first coat thereon at an elevated temperature and the resultant 25 hydrophobic composite is thereafter cooled to ambient tempera ture.

18. The method of claim 13, wherein said core material is selected from the group consisting of sand, gravel, mine tailings, coal ash, natural rock, smelter slag, 30 diatomaceous earth, crushed^<^fa^SE)sJl, sawdust, mica, wood chips and nut shells. 1 /••V T2 9 MAY 1937 208902 -19-

19. The method of claim 13, wherein said core material has a particle size in the range of 25 millimeters to 125 microns.

20. The method of claim 13, wherein said core material 5 is a siliceous substance. substance is selected from the group consisting of sand, gravel and slag.

22. The method of claim 13, wherein said second coat 10 includes a powdered abrasive material.

23. The method of claim 22, wherein said powdered abrasive material comprises powdered corundum.

24. The method of claim 22, wherein the particle size of said powdered abrasive material is less than 50 15 microns.

25. A water-repellent coating composition comprising an aggregate of Lhe hydrophobic composite of claim 3 and a binding agenL.

26. The composition of claim 25, wherein Lhe binding 20 agent is a liquid binding agent selected from the group consisting of asphalL, coal tar, paint, varnish, lacquer, liquid plastic and adhesive maLerial.

21. The method of claim 20, wherein said siliceous

27. The composition of claim 25, wherein said binding agent comprises less than 10% by weight of said composiLion. By 'neir - ■ A.J. PARK & SON _ 2 9 my 1987 </div>