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Title: Product and process
Description: Description:
The present invention relates to compositions which are particularly useful in coatings that can provide galvanic protection when cured on ferrous substrates. These coatings contain as essential ingredients solvent-soluble, aliphatic-polyol-derived silicate (hereinafter sometimes referred to as "polyol silicate") and metallic zinc filler in finely divided form. The invention is also directed to liquid solutions containing the polyol silicate and an organic solvent for the silicate which solvent is compatible therewith and does not cause the composition to rapidly gel or change greatly to produce an undesireable composition. Although these polyol silicates and their solutions may be used in various types of compositions, the invention especially combines metallic zinc-containing fillers with these materials to provide slurries or dispersions which are relatively stable as single component or single package coating compositions and which can be applied and cured as coatings on ferrous surfaces and thereby protect the substrates by galvanic action against the deteriorating effects of corrosive environments. Aside from the zinc filler, the compositions may preferably also contain other finely divided filler materials, and, in this regard, alumina in its various forms may be used to decrease the amount of zinc that might otherwise be required to provide satisfactory coatings. The addition to the compositions of this invention of weakly-basic, heterocyclic, unsaturated nitrogen compounds may serve to prevent agglomeration of the zinc dust particles during storage and to prevent gassing of the compositions. The polyol silicates and their solutions of this invention can also be used as ceramic molding compositions containing the various fillers disclosed herein, with or without metallic zinc. Many of the polyol silicates of the present invention, when composited with finely divided metallic zinc-containing fillers, give relatively stable products which remain essentially ungelled and in usable condition over exceptionally long periods of time. These preferred products when kept in a moisture-tight and air-tight container, are stable for relatively long periods of time against substantial changes in properties, and are ready for easy use without further additions being necessary. Thus, these preferred compositions offer the great advantage of being single-component coating compositions which are more stable for longer periods of time than heretofore known alkyl silicate binder-containing coating compositions, and which can be readily applied to ferrous substrates and very rapidly self-cured under various atmospheric conditions -- dry, rainy, cold or hot -- to form rapidly upon curing strongly adherent, relatively hard, stable, galvanically-protective coatings. The present invention is also directed to a variety of multiple package coating compositions of exceptional properties. In one of these, one package of the two-package system contains the polyol silicate, while the finelly divided zinc is in another package. Either or both of these packages may contain additional ingredients, e.g., the polyol silicate may be dissolved in a solvent and contain a dispersed filler, and the zinc package may contain a variety of fillers, e.g. alumina. In another preferred form of the invention, one package designed to be added to a polyol silicate package, is comprised of finely divided zinc dispersed in an organic solvent, e.g. methyl ethyl ketone, and an acidic zinc salt such as zinc chloride, and this package may also contain one or more other fillers such as silica, zircon, clay, alumina, talc and the like. These ingredients, with or without the elemental zinc, may also serve as curing catalyst formulations when combined with silicate-type coating compositions, which may or may not contain elemental zinc. The zinc metal-containing filler package may be added to the polyol silicate package shortly before use. The compositions of this invention may also contain minor amounts of other ingredients such as organic polymers, e.g. polyvinyl materials, particularly those having reactive OH groups, for instance, polyvinyl butyral, preferably reacted with the polyol silicate to form stable, one package binders for zinc paint. All of the compositions of this invention may contain inorganic fillers, anti-sag agents, thickening agents, suspending agents and the like to stabilize, actuate or dilute the compositions and provide easy to use, preferably single package, zinc paints. The present invention is further directed to certain of the polyol silicates which are novel products, and which in the most preferred form, can be employed in single-package, zinc-containing, galvanic coating compositions. By the present invention, I have also devised advantageous ways of making the polyol alkyl silicates which are essentially ester-exchange reaction products of ortho silicates and polyhydric alcohols, particularly the ester exchange products of ethylene glycol and lower alkyl and C.sub.3 to C.sub.7 alkoxyalkyl silicates, including their siloxane forms, preferably having up to about 8 SiO groups per average molecule. The products are useful in the single package, zinc-containing compositions of this invention, which can be stored in a container in ready-to-use condition. I am aware that serious difficulties exist in making and using presently available galvanic coating compositions containing metallic zinc and inorganic silicate binders, and effort expended towards devising products containing an organic silicate binder and metallic zinc is in order to obtain improved coating and protective characteristics. Commerically-available products have not been sucessful in eliminating the problems inherent to these materials. Such products are disclosed in U.S. Pat. No. 3,056,684, and contain a partially hydrolyzed, tetraethyl orthosilicate as the organic silicate binder. Other galvanic coating compositions have been based on the use of hydrolyzed tetraethoxyethyl silicate as the binder, but the variety of available organic silicate-based galvanic coating compositions is limited. Moreover, these conventional hydrolyzed silicates, if they are highly enough hydrolyzed to cure rapidly with zinc as a paint, have a poor shelf life of only a few months and a pot life, when mixed with zinc dust, of only a few hours. As a consequence, these components are maintained as separate packages until shortly before use, whereas certain of the products of the present invention may be made into single package, stable compositions containing both the silicate binder and zinc dust. Further, the conventional hydrolyzed silicates, if they have good shelf life in the presence of zinc dust, may not cure rapidly at lower temperatures and humidities, if at all, and their application as coatings is often prohibited under a variety of weather conditions that do not hinder the use of the compositions of the present invention. Thus, my compositions can have improved pot life and shelf life and cure under all weather condtions. One purpose of the present invention is, therefore, to provide new fat-curing, stable, easier-to-use galvanic coating compositions containing meetallic zinc and polyol silicate reaction products having superior coating and curing characteristics under a variety of application conditions such as adverse weather, and which provide highly advantageous galvanically-protective coatings when cured on ferrous substrates. Prior organic silicate coating products have a number of disadvantages, and, in particular, they may not be formulated into rapidly-curing, single-package, galvanic coating compositions without severe limitations. Thus, the pot life of some of these silicate products, when mixed with finely divided metallic zinc, is so short, e.g. about four hours, that the compositions cannot be marketed or used on a practical basis as a single package. Instead, the user of the product must mix the silicate binder with the metallic zinc more or less at the time the composition is to be applied to the ferrous substrate. In many situtations, this is a severe disadvantage to the coatings applicator and he must carefully control the operation to insure that the zinc-containing product is applied quickly as a coating, otherwise it may gel prematurely and cause waste and perhaps even the loss of equipment in which the premature curing action occurs. The products of U.S. Pat. No. 3,056,684 currently marketed are of this type and thus do not permit the formulation of satisfactory rapidly-curing, zinc-containing, galvanic coating compositions having a pot life of over a few hours. There is possibly one other single package, zinc-containing composition on the present commercial market, but its properties are quite inferior in making rapidly-curing, hard, adhesive coatings. In any event, the art is in great need of improved organic silicate-metallic zinc products of the single package variety in order that the coatings applicators may have faster curing, harder and more adhesive coatings under a variety of adverse application conditions than afforded by the products available, and so that a more appropriate selection can be made to satisfy the ultimate requirements for the coatings in a greater number of given situations. Heretofore, the most widely used zinc and silicate-containing coating compositions employed for the protection of metallic substrate surfaces, have been, to my knowledge, characterized by a hydrolyzed silicate binder having nearlly completely a -Si-O-Si- polymeric and cross-linked structure. Such previous paint compositions containing substantial amounts of the -Si-O-Si- structure, if they are sufficiently hydrolyzed to cure rapidly with zinc dust, are not reliable if requiring long storage, since they tend to form lumps when combined with zinc dust, develope gaseous pressure or even form solid gels upon long-aging, even without zinc dust being present. Consequently, such prior zinc-silicate coatings had to be blended or mixed at the point of use, due to the necessity of keeping various constituents of the ultimate coating composition in separate container prior to its application, and even as a two package system, the silicate portion was subject to being unusable after six months to a year or more of aging. Where such blending or mixing had to be carried out manually by the operator, it was difficult and sometimes not possible to provide smooth blends free from lumps that would cause clogging of spray equipment if the paint compositions were applied by spraying. Also, the "pot life" of the zinc-silicate materials was often limited to from 2 to 12 hours, and clogging of conduit lines with solid zinc silicate particles presented a real problem, particularly where such lines were exposed to high temperatures, as on the hot decks of ships. In addition to the necessity of making available separate coating containers in the previous use of silicate coatings, the container for the highly hydrolyzed alkyl silicate or organosol, if made of steel had to be lined with a special, relatively expensive, corrosion-resistant lining, since otherwise the coating composition would ge or become unusable upon extended contact with the iron-containing surface, because of the instability of the composition. In my novel "one-package" system, a simple unlined paint can suffices and is highly satisfactory, without any special coating or lining, for storing my liquid suspension coating compositions. Some of these coating compositions of my invention when properly compounded have a pot life of several days to many years. The longer stable products offer an inorganic zinc composition ready for use right out of the can sold from the shelf of a paint store for use in the home, in preconstruction primers, on ships, in industrial plants or in aerosol cans or drums for spraying. Others of my compositions that may be especially prepared for certain fast-curing applications, may have a pot life of about 1 to 40 weeks or longer and can be made and used before gelling or changing enough to materially reduce their advantageous coating characteristics. To suspend the zinc dust, it is often advantageous to highly shear suspending, antisaging, and antisetting fillers in the polyol silicate binder, prior to slowly stirring in the zinc dust. Zinc and othe filler particulates, whether in the form of fillers containing finely divide elemental metal, even metal dust, or metal silicate, or in the form of zinc silicate, are so difficult to mix and suspend into a liquid without lumping that controlled mixing or blending, such as can be practiced in a paint factory, or the like, is far superior to leaving it up to the operator to mix the constituents manually (and usually ineffectively) at the locus of use in the field. Some of the advantages of my new compositions are that they can be preblended in large batches and made up into single package compositions, ready for instant use for a coating application or they can be activated by adding an accelerator just before using. Additional advantages are that they may be made self-curing, do not freeze, are not subject to bacterial attack, can be used in the form of an aerosol, can be attractively pigmented for high temperature color coatings, and have rapid curing characteristics, making possible painting in winter and painting using automated programmed dipping, spraying and curing cycles, such as the application of a preconstruction primer which may later be welded together and recoated with the zinc silicate paint and for coating rolled steel which is subsequently recoated, formed or coiled. In addition, the zinc dust-containing coatings provide exceptional rapidly self-curing, galvanic, porous coatings for ferrous surfaces, and can be incorporated into single package or separate package compositions as desired. The single package characteristic makes the coating material ready for instant application by the user who otherwise may be required to stir for days to assure breakup of lumps, if, indeed, this can be even be practically accomplished. In addition, the single package permits attaining homogeneous and quality-controlled thixotropic slurries of the suspending agents in a larger plant, rather than mixing in small uncontrollable batches at the locus of use. Because of the exceptional adhesion of these coatings, they often can be applied even to surfaces having poor preparation and even over scale and give good protection. My novel long pot life or single component, stable systems which are one preferred form of the present invention, make it possible to apply the coating composition by dipping in large tanks, whereas the relatively short pot life of prior zinc silicate coatings precluded any possibility of successfully dipping large objects in the zinc dust-silicate paint because gelling or degradation would occur within a few hours and a new batch of zinc dust-silicate paint had to be provided for continuing the operation. The resulting loss was sufficiently great to prevent the adoption of large scale dip-coating of ferrous objects and surfaces. As indicative of their ease of application, my novel one-package, zinc-silicate paint compositions can be applied by conventional means, including spraying, brushing, rolling or dipping, or by the so-called "airless" spraying technique. Another important benefit of some of my compositions is that they can be formulated with a high boiling solvent to give a product having a flash point of over 100.degree.F. One of the important benefits of some of my compositions is that they can be packaged in a container, such as an ordinary paint can, and kept therein indefinitely, ready for use at any time as self-sufficient coating compositions requiring no mixing with other compositions or additives. When placed in a moisture and air-tight container, these compositions remain smooth, free from lumps and without any tendency to gel or become objectionably viscous when tightly sealed. Some of my preferred composition have such properties even when the finely divided zinc component is included to give a composition ready for application to a supporting substrate. When applied and dried, the compositions cure in the presence of air and moisture in a minimum amount of time under evaporative conditions to give relatively hard, strongly adhesive coatings having exceptionally good protective properties toward corrosion and having self-healing properties toward scratches that may be formed on the surface of the coating. This self-healing property is particularly advantageous where the coating is exposed to salt or other corrosive atmospheres. The strong adhesion of the coating to the substrate surface, even when applied to non-sandblasted, but otherwise clean ferrous metal surfaces, is especially advantageous where subsequent coatings to be applied do not adhere well to the surface of the substrate itself, such as where certain plastics are to be applied to a surface of a steel, aluminum, glass or ceramic substrate to which such plastics ordinarily do not bond. Thus, the metallic zinc-containing coating compositions of my invention can suitably be used as a primer for application to a substrate to condition the surface thereof for another of the same or other coatings, even when a coating containing a plastic or polymeric material or an inorganic, ceramic or porous topcoat. Another advantage of some of my coating materials is that they have exceptional protective properties at high temperatures, such that a finished, dry coating of my composition on a 20-gauge, cold-rolled steel test plate can be heated to red heat and then quenched in cold water without the slightest indication of cracking or decomposition of the coating material. The thermal cycle of high temperature heating and low temperature quenching can be repeated many times without any apparent degradation of the coating. The exceptional heat resistance of my composition is believed to be due to the driving-off by evaporation on exposure to air and moisture of all organic groups to leave the inorganic grouping --SiO.sub.2, ZnO, SiO.sub.2 --, zinc silicate and possibly zinc oxychloride, which is stable up to red heat temperatures, such as 1100.degree. to 1200.degree.F. Coatings formulated from my polyol silicates made from ethylene glycol, particularly when methyl ethyl ketone, zinc dust-containing fillers and optionally an acidic zinc salt such as a zinc salt of a mineral acid, e.g. zinc chloride, or mineral acid catalyst, are used in the products, exhibit a very strong, tenacious adhesion to metal substrates. The protective surface not only provides a decorative gray color, but also enhances the resistance of the metal substrate to oxidation, rusting or other forms of corrosion. The adhesion of the coating to the substrate is so extremely strong as to indicate the possibility of a chemical reaction between the silicate, acidic zinc salt, and ferrous metal-containing substrate. A chemical bond between the coating and the substrate seems most likely in view of the fact that the coating on the substrate successfully withstands bending, impact and thermodegradation. The organic silicate binders of the products of the present invention are ester-exchange reaction products made from polyol and organic silicate. The silicate reacted with polyol is essentially composed of ortho silicate whose major portion of organic substituents is essentially of aliphatic, including cycloaliphatic, configuration, although a minor amount of non-aliphatic radicals, e.g. aromatic groups may be present. The organic radicals of the essential ortho silicate are generally saturated and each may have up to about 6 or 7 carbon atoms, preferably up to 4 carbon atoms. These aliphatic radicals which are attached to a silicon atom through an oxygen atom, consist essentially of carbon and hydrogen, and often contain oxygen, particularly in the case of ether, ether-alcohol, alcohol, or even ester groups. For example, the silicate reactant may contain ortho silicates in which the organic radicals are in the form of alkyl, hydroxyalkyl, alkoxyalkyl, hydroxyalkoxyalkyl or carboxyalkyl groups attached to a silicon atom through an oxygen atom, and preferably these groups have straight chain or primary structures. At least two of the organic groups per molecule of at least a substantial portion of the essential silicate reactant are ester-exchangeable with the polyol reactant. Also, these aliphatic or alkyl-type silicate reactants may contain one or more siloxane groups, that is, --Si--O--Si--, in aliphatic or cyclic and cross-linked configuration. Thus, the silicon atoms may be bonded through oxygen to 1, 2, 3 or 4 other silicon atoms with its other valences being satisfied with an organic radical of the types described herein. The silicate reactant, when in siloxane form, will often have up to about 5 or 10 silicon atoms per average molecule, and preferably not more than an average of about 6 silicon atoms. If the silicate reactant is hydrolyzed to a greater extent, its structure may contain a larger number of the siloxane groupings, and they may be in cyclic, crosslinked configuration. When the silicate reactant is hydrolyzed, I prefer it to be up to about 75% hydrolyzed, preferably up to about 45% hydrolyzed for single package paints. For two package paints, the preferred extent of hydrolysis is up to about 75%. Mixed or blended silicates differing in extent of hydrolysis may also be useful reactants. With hydrolyzed silicates, the reaction with polyol decreases cure time and this is a particularly important property with silicates that are hydrolyzed below about 75% since these products also have longer shelf-life than higher hydrolyzed products. The siloxane-type structures are considered herein to be ortho silicates, i.e. the four valences of the essential silicon atoms are bonded through oxygen atoms to either carbon or another silicon atom in cyclic, cross-linked, or aliphatic chain configuration. The ortho silicate reactants employed in making some the binder components of the present invention include, among others, those having the formula: ##EQU2## in which the R groups may be similar or dissimilar alkyl-type radicals having up to about 4 or 6 carbon atoms, e.g. alkyl, hydroxyalkyl, alkoxyalkyl, hydroxyalkoxyalkyl, carboxyalkyl and the like, and y is 0 or a number up to about 5, 6 or 10 or more, e.g. about 3 to 9, to provide a siloxane structure. Preferably, y does not exceed about 7 for the average molecule. The siloxane structures may be disposed in a simple single ring or may be in multiple, rings formed by cross-linking, e.g., as represented by the following examples: ##SPC1## The R groups may be the same or different in a given reactant. Also, most of the R groups are not stearically-hindered to the extent that the reaction will not take place. Included among these useful R groups are alkyl of up to, for instance, 4 carbon atoms, e.g., methyl ethyl, propyl and butyl groups. Tetraethyl ortho silicate, polymeric ortho silicates of about 4 to 10 silicon atoms per molecule, ethoxyethyl or methoxyethyl silicates, mixed esters of alkyl and alkoxyalkyl silicates, and the like, are highly preferred reactants. The mixed ester silicates may especially have ester-exchangeable groups which are predominantly alkoxy alkyl. The R groups may also be alkoxyalkyl or carboxyalkyl radicals of 2 to 6 carbon atoms, such as ethoxyethyl, methoxyethyl, carboxymethyl and the like. Another type of alkyl ortho silicate which may be employed in making my binders are those in which one or more R groups are hydroxyalkyl such as hydroxyethyl, hydroxypropyl, and the like, or R groups in which are contained both ether and alcohol oxygen atoms such as hydroxyethyloxyethyl, and in the case of the latter, only minor amounts may be desirable due to the low volatility of this substituent. The ortho silicates which can be employed in preparing the binders of the present invention may contain minor amounts of other ingredients, some or all of which may be of silicate configuration and monomeric or polymeric in form. A preferred essentially monomeric reactant is a tetraethyl ortho silicate containing, for instance, about 75 to 95% or more monomer, and a small amount, for instance, about 4 to 10 or 20% of dimer having the formula: ##EQU3## as well as a minor amount of higher polymers. One product of this type which is commercially available is designated "ethyl silicate condensed," and contains about 90 to 95% of tetraethyl ortho silicate, 4 to 9% of the above dimer in which R is ethyl, and a small amount, say about 1%, of higher polymers. A highly preferred reactant is commercially available under the name of "Ethyl Polysilicate 40" , which may not only be transesterified by reaction with polyol, but also with monohydric compounds such as 2-ethoxyethanol, 2-methoxyethanol, and the like to give mixed ester products. The ortho silicate reactant may thus include various monomers and polymers and mixed monomers and polymers of the ortho silicate type, having minor amounts of silanes, having a minor amount of carbon-to-silicon bonds, and having carbon--oxygen-silicon linkages, with or without silicon-oxygen-silicon linkages. Materials of these types may include minor amounts of tri- or di-alkoxy silanes containing other radicals attached by a carbon-silicon linkage, as well as polymers of these various materials. Thus, the alkyl ortho silicate may have a co-mixture of an alkyl silicate, such as tetraethyl ortho silicate and polymers thereof, and a mono- or di-alkyl or aryl, alkoxy silane, such as propyl trimethoxysilane, to form a product containing the reacted form of such materials. The silicon-carbon bond may in some instances increase the water repellancy of the protective coating and offers the possibility of the organic portion of the product having functional groups which may bond to a functional group on a plastic top coat or an antifoulant coating material to improve the adhesion to a substrate. The polyol silicate binders of this invention are essentially reaction products of the above-described ortho silicates with aliphatic, including cycloaliphatic, polyols which are preferably diols or triols, but may have many hydroxyl groupings per molecule. The essential polyol reactant may be partially etherified or otherwise modified providing it has at least 2 free hydroxyl groups per average molecule to participate in the ester-exchange reaction. Other hydroxy-bearing materials may be present and may or may not ester-exchange with another reactant, e.g. the ortho silicate reactant. Thus, the polyol-silicate reaction mixture may contain a monohydroxy reactant such as an alkanol, ether alkanol or the like, and such monohydroxy material may be mixed or ester-exchanged with the polyol silicate while or after the latter is formed. Although the polyol or monohydroxy material may have a molecular weight of up to about 200 or 400 or more, especially if they are polyoxyalkylene polyols, such as the polyoxyalkylene glycols, e.g. polyethylene glycols, or alkyl-capped, polyoxyalkylene polyols, the polyols and monohydroxy materials often have molecular weights up to about 100. Higher molecular weight polyols are usually a minor molar amount of the total polyol employed with the lower molecular weight polyol being the major amount. Preferred polyols are ethylene glycol, propylene glycol and glycerol, and ethylene glycol is the most highly preferred polyol reactant from both the product quality and cost standpoints. Although the polyol silicate binders of this invention consist essentially of carbon, hydrogen and oxygen, they may contain other elements such as nitrogen, as is the case when diethanol amine or triethanol amine is employed as a polyol reactant, although these polyols may not be preferred. The polyol silicates derived from nitrogen-containing polyols may be employed along with polyol silicates derived from other polyols, and such mixtures may be prepared by physical admixing or sequential ester-exchange. Such mixtures preferably contain a major weight portion of polyol silicates derived from non-nitrogenous polyols, and a minor amount of the nitrogen-containing polyol-derived polyol silicate sufficient to improve the stability of the compositions. The use of nitrogen-containing, polyol-derived polyol silicates may serve to reduce lumping of the zinc dust and gassing of the composition. Other polyols which may be employed in making the binders of the invention include diethylene glycol, trimethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycols, trimethylol propane, 1,6- or 2,6-hexanediol, neopentyl glycol, 1,3-butylene glycol, pentaerythritol, sorbitol, hexylene glycol, partially-esterified polyols, cyclopentanediol and the like. Mixtures of these polyols may also be reacted, especially those which contain a major portion of ethylene glycol, propylene glycol or glycerol. The choice of polyol may affect the gelling characteristics of the product, for instance, if higher molecular weight polyols having several hydroxyl groups are used, proper adjustment to lower ratios of polyol with respect to the silicate reactant on the basis of the number of hydroxyl groups per ester-exchangeable group in the silicate is advisable, and the extent of alcohol removal or addition from the ester-exchange reaction mixture may be varied to obtain a hard, adhesive coating, yet having a mixture that will not gel as a single package, zinc-containing paint due to excessive cross-linking. The use of polyols having more than 3 carbon atoms may lead to slower curing products, especially as the ratio of polyol to silicate increases and thus the use of polyols having up to 3 carbon atoms is preferred for materials having no residual organic materials in the coating. Similarly, the gelling characteristics of the reaction mixture and properties of the coating compositions may be affected, depending upon the choice of the silicate reactant and the extent of ##EQU4## and silicon-carbon bonds that may be present. The use in high ratios to silicate of higher molecular weight glycols or other polyols having other groupings thereon and less volatile, may lead to products which are slow-curing and give soft coatings due to their low volatility. This may indicate the use of only minor molar amounts of these polyols based on the total polyol reacted. The ester-exchangeable, monohydroxy components which may be ester-exchanged into the polyol silicate reaction products of this invention are monofunctional materials, and they generally have a higher boiling point than the alcohol formed as the result of this ester-exchange. These monohydroxy materials may have a molecular weight up to about 300 to 400 or more, usually a molecular weight below about 100, and they often consist essentially of carbon, hydrogen and oxygen. Among these monohydroxy reactants are the alkanols, ether alkanols, keto alkanols and the like having, for instance, up to about 24 carbon atoms, but preferably up to about 4 or 8 carbon atoms. Thus, materials such as branched alcohols may be used to impart stability to the coatings ultimately formed, and, in this respect, even t-butyl alcohol and 2-ethylhexyl alcohol may be employed, although not preferred. Among the useful alkoxy alkanols are methoxyethanol, ethyoxyethanol, and the like. Alkyl-terminated ether glycols may also be reacted, e.g. methyl-terminated diethylene glycol, CH.sub.3 OCH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 OH. When used, the low volatility, monofunctional, polyethers are preferably present in minor amounts compared with the highly desirable alkyl-terminated monoether alcohols such as 2-ethoxy ethanol and methoxyethanol. The amount of monohydroxy material reacted during the formation of the polyol silicate or subsequently, any range from very small proportions up to preferred amounts sufficient to ester-exchange with essentially all of the ester-exchangeable groups of the polyol silicate, and even amounts in substantial excess being present as a solvent. Preferably the amount of monohydroxy material is sufficient to stabilize the polyol silicate against gelling and may vary according to the ratio of polyol to silicate reacted, the extent of hydrolysis of the silicate, and the presence of zinc or other fillers or polymeric materials such as polyvinyl butyral in the composition. The ester-exchange reaction can be conducted under the conditions disclosed herein for forming the polyol silicates of this invention. In the case of polyol silicates made from siloxane reactants having a plurality of ##EQU5## bonds, the presence of substantial amounts of monohydroxy materials in the product or the reaction mixture in which the polyol silicate is formed, can serve to reduce the gelling tendencies of the polyol silicates when metallic zinc is or is not present. This stabilizing effect is particularly apparent when the monohydroxy material is alkoxy alkanol. Preferably, this amount is a substantial molar excess of monohydroxy material based on the ester-exchangeable groups of the polyol silicate. Apparently, even at low temperatures in the presence of an acid catalyst, the monohydroxy material ester-exchanges into the polyol silicate structure, and this reaction takes place much more rapidly at elevated temperatures. The ratio of silicate and polyol reactants reacted in making the binders of the present invention may affect the structure and properties of the resultant products, as well as the manner in which they may be used in coating compositions. Generally, the binder reaction products are made by reacting polyol and silicate in amounts such that the ratio of hydroxyl groups supplied by the reacted polyol is about 0.15 to 1.8 moles per mole of ester-exchangeable group provided by the reacted silicate, preferably this amount is about 0.35 to 1.5:1 or even about 0.5 to 1.3:1, or, in the case of monomeric silicates, even about 0.5 to 0.9:1. These preferred amounts are especially advantageous in making single-package, zinc-containing, galvanic coating compositions. In the case of tetraalkyl silicate and glycol reactants, these amounts may correspond to about 0.7 to 3.5 moles of glycol per mole of tetraalkyl ortho silicate, preferably about 0.7 to 3:1 or even about 1 to 1.9:1. In the case of silicate esters having siloxane polymers therein and having an average of about 5 to 7 silicon atoms per molecule, ratios of about 0.3 to 3.5, preferably about 0.7 to 3.5, moles of hydroxy group supplied by the reacted polyol per mole of silicon atom in the siloxane, are preferred. Minor amounts of unreacted polyol may also be present in the products and serve as a solvent or suspending agent for the zinc dust, although the amount of unreacted polyol should not be so great as to cause gelling. Generally, with the presence of many siloxane groupings in the molecule of the silicate reactant, smaller amounts of polyol per unit of siloxane may be used to produce coating compositions of desirable curing characteristics. As the number of siloxane groupings increases in the silicate reactant, the use of smaller amounts of polyol per silicate unit ##EQU6## in the polysilicate molecule may be necessary to prevent gelling because of the large number of sites per molecule available for cross-linking, and thus, especially with highly hydrolyzed silicates, the tendency to gel is great if the polyol silicate products are not highly diluted with a solvent, preferably with a stabilizing monohydric alcohol or alcohol ether compound such as 2-ethoxy ethanol, and in the highly hydrolyzed binders, the silica content of the ester-exchange product may be about 14% or less in order to be stable to gelling tendencies. The preferred reacted ratio of glycol to silica in the binder changes with the extent of hydrolysis of the silicate, and may also be described in the terms of the pounds of glycol per 100 pounds of silica present in the binder for preferred curing characteristics and stability against gelling. For instance, the monomer, tetraalkoxy or tetraalkoxyalkyl silicate, when essentially 0% of hydrolyzed (unhydrolyzed) may have an optimum ratio range of around 105 to 200 lbs. of glycol for each 100 lbs. silica (calc. SiO.sub.2 of mol. wt. 60) present in the binder; for the dimer of this silicate having about 25% hydrolysis, the optimum ratio may be around 80 to 105 lbs. of glycol for each 100 lbs. silica present in the binder. When using a silicate which is about 40% hydrolyzed, e.g. ethyl silicate 40 having an average of about 5 silicon atoms per molecule, an optimum ratio of about 55 to 140 lbs. of glycol per 100 lbs. of silica may be present in the binder. For a silicate that is hydrolyzed to about 70%, it may be necessary and advisable to react only about 10 to 50 lbs. of glycol for each 100 lbs. silica in the binder to achieve adequate shelf life and adequate curing of the coating. The latter binder is useful in two package systems having limited shelf life and should be highly diluted with monofunctional hydroxy compounds to achieve non-rapid gelling characteristics. It must be noted, however, that as the hydrolysis increases, the stability of both the polyol silicate and the slurry containing the polyol silicate and zinc decreases, and dilution with adequate monofunctional compound and adjustment of pH (buffering) to prevent rapid gelling become increasingly more necessary. The binder stability is far longer than the zinc slurry, since the zinc tends to react with the higher hydrolyzed binders. For instance, a polyol silicate made from a 95% hydrolyzed silicate may have a can life in the presence of zinc dust of only 1 day or even 5 hours before gelling, while the can life of a polyol silicate made from a 40% hydrolyzed binder may be many years, even in the presence of zinc dust, particuularly when buffering agents (fillers) are present. The can life of a polyol silicate made from a 95% hydrolyzed silicate and having no zinc dust may be no longer than a few weeks when highly diluted with monofunctional solvent and having a less acidic pH, while the can life of a 75% hydrolyzed silicate derived binder is much longer, particularly when diluted with a monofunctional-OH solvent. For a binder made from a 40% or less hydrolyzed silicate diluted with some monofunctional-OH solvent may have a shelf-life of many years under sealed ambient conditions. It should be noted that the presence of the glycol or polyol ester-exchanged into the silicate can give faster curing coatings with zinc dust than would ever have been possible without the polyol (at the same silicate hydrolysis); and hence, the addition and ester exchange of the polyol into the silicate helps achieve a coating having a rapid cure at low hydrolysis (0 to 60% hydrolyzed), where ordinary hydrolyzed silicates would never normally cure, without added accelerators, as coatings with zinc dust, and this coating would be very soft. The low hydrolysis of the silicate employed is advantageous because of highly extended can life of slurries with zinc, and hence, rapid curing single package compositions of polyol silicate binders and zinc dust, which are stable for long periods of time, and yet when applied as a film, cure out very rapidly to hard superior adhesive coatings. In any event, enough of the polyol is ester-exchanged with the silicate to give a product having improved rapid curing characteristics compared with those of the silicate reactant itself, regardless of its extent of hydrolysis, but being more noticeable in rapid curing at the lower hydrolysis extents up to about 60% hydrolyzed as compared to binders not having the polyol reacted therein at these lower hydrolysis extents. I have found that silicon-to-carbon bond containing reactants or silicone polymers can sometimes be usefully incorporated in minor amounts in the novel backbone of my silicate and polysilicate products, although, for inorganic zinc coatings, these may not be preferred. Examples of such reactants which may be so incorporated are methyl triethoxy silane, propyl trimethoxy silane, vinyl trimethoxy silane and hydroxy functional silicone polymers. Cross-linking of the silicate product can be effected by attaching a functional organic grouping to the silicon of the silicate product which may then be made to chemically bond to a plastic topcoat containing a reactive grouping. The following table gives considerable data with regard to the physical form and properties observed, analytical results obtained and postulated chemical structures of products prepared by reacting the simplest of the aliphatic ortho silicate, specifically tetraethyl ortho silicate, with the simplest glycol reactant, specifically ethylene glycol, under conditions effecting an ester-alcohol exchange with accompanying near total removal by distillation of alcohol released from the reaction mass to show how the compositions change with various ratios of silicate/polyol, and the chemistry involved. This study was conducted to establish the structure of the tetraalkyl silicate-glycol ester exchange products, and the chemistry could be extrapolated to polysilicate/polyol reactants, but because of the number of available reaction sites and cross-linking possibilities, only characterization of the products from monomer reactants was attempted. These products were made by removing essentially all alcohol to the point of gelling of the product to show how the structures change upon curing. Certain information has been omitted from the table in the interest of conserving space. Such information includes the following: As to the boiling points of the glycol alkyl silicate reaction products of my invention, the mole ratio of glycol to silicate is important. When the ester-exchanged and reacted mole ratio of glycol to tetraalkyl ortho silicate ranges from about 0.5 to below 1 glycol per mole of tetra ortho silicate, the resultant products are extremely thermally stable and contain structures having predominately the following grouping when ester-exchanged released alcohol is removed, causing the bridged structure to predominate: ##EQU7## where n is greater than 1 and the R' groupings are alkoxy. As the ratio of glycol to tetraalkyl ortho silicate is progressively increased from 1 to less than 2, the structure of the silicate progressively changes from bridged to pendant glycol which, with excessive heating and removal of monofunctional compounds, gels the resultant polymer, possibly through cross-linking-ester exchange condensation of pendant polyol groupings with monofunctional alcohol groupings on the silicate, and possibly resulting in rearrangements with release of alcohol from the predominant structure present in this ratio range which must be carefully made so as to not exceed the temperature and degree of alcohol removal where gelling and rearrangement occur. As the ratio of glycol to silicate increases from 2 to 3.5:1, the ratio of pendant to bridged glycol structures increases even more when alcohol is removed. These products may be characterized by the above structure wherein n is usually only 1 or 2 and the R' groupings are both alkoxy and pendant glycol (hydroxyakyloxy). At ratios of over 4 moles of glycol/1 mole tetraalkyl silicate, the structure is ##EQU8## and this material is well-known and distillable under vacuum. As to the physical forms of my reaction products, they are all colorless and range from non-viscous through viscous, syrupy, semi-solid, but flowable, to semi-solid and non-flowable substances. As to the solubilities of my products as identified in the following table, product No. 1 is soluble in all hydrocarbon solvents and oxygenated organic solvents, but insoluble in water; No. 2 is soluble in aromatic hydrocarbon solvents; insoluble in paraffinic hydrocarbons, soluble in oxygenated solvents; and insoluble in water; Nos. 3 through 6 have the same solubilities as No. 2; No. 7 is insoluble in aromatic hydrocarbon solvents, soluble in ketones and insoluble in water; No. 8 is insoluble in most organic solvents except hot alcohol and compounds having an active hydrogen. It should be noted that any of the above will be water-soluble if water is very slowly added to acidic solutions to increase hydrolysis and solubility, and could be classified as miscible if added extremely slowly to allow hydrolysis reactions to occur before adding the remaining water. The following table gives further data as to the same reaction products identified above and in the table as Nos. 1 through 8. As to products Nos. 1 through 8, the mole ratio of ethylene glycol to tetraethyl ortho silicate is increasing from 0.5 mole glycol/1 mole tetraethyl ortho silicate in No. 1, to 3 moles of glycol/1 mole tetraethyl ortho silicate in No. 8. As the glycol ratio is increased, the structure changes drastically from products having the glycol-alkyl silicate backbone structure, ##EQU9## in which both hydroxyls of essentially all of a given glycol molecule are bonded to different silicon atoms in the ratio of 0.5 to 1 mole glycol per mole silicate, to predominately tye pendant-type structure in which only one hydroxyl group of the glycol is bonded to a silicon atom. Glycol alkyl silicate molecules with perhaps only one or two of the ##EQU10## backbone groupings per molecule were formed when there was a mole ratio of 1 mole of tetraethyl ortho silicate to less than 2 moles of glycol, and perhaps less than 1 as the ratio increases from 2 to 3.5 and the products had none of these backbone groups when the mole ratio was over 4 glycols/1 silicate and substantially all alcohol was distilled therefrom. In each instance in making these products, I withdrew only enough alcohol to polymerize the reaction mixture to a very viscous, but not a solid, insoluble, consistency. It is noted that in the data table, the analysis and structure postulated are based on average composition. It is assumed that a distribution of products occurs having masses higher and lower in molecular weight, but averaging to the given composition, and they are not just a single compound. While these data are applicable to the monomer, it can readily be seen that siloxane polymers having a greater number of available sites for cross-linking by ester exchange with a polyol, behave similarly to the monomer and have the same ratios, based on hydrolyzable grouping on the silicate reactant, and similar structures, but, because of their complexity, are more dependent on dilution with monohydric compounds to prevent the cross-linking reaction of the pendant type glycol with alkoxy groupings on other silicate molecules because of the numerous available sites present for ester exchange increases as the siloxane polymer gets larger from increasing hydrolysis. The chemical mass action law probably applies wherein the affinity of the polyol grouping to undergo cross-linking is counteracted (or stabilized against gelling) by the monohydric compounds whose affinity for the silicon atom and amount present on equilibration with the polyol prevent such cross-linking and gelling reactions from occuring, as happens with the polyol until, as the coating dries and the reaction solvent evaporates, the cross-linking reaction occurs. The control of molecular weight (viscosity) of the polyol silicate by addition or removal of monohydric compound is shown in its simplest form, for the monomer in equation Y below.
TABLE I
__________________________________________________________________________
Moles
Analysis of Product alcohol
Mole Refrac- collected
Pro-
Ratio tive Molec-
per mole
duct
Silicate/
Index,
Density,
% % % % ular
of glycol
No.
Glycol
30.degree.C.
25.degree.C.
SiO.sub.2
C O H wt. charged
__________________________________________________________________________
1 1/0.5 1.4004
1.004 31.1
43.2
32.2
8.3 386 2/1
2 1/0.9 1.4106
1.062 -- -- -- -- -- 2/1
at 29.degree.C.
3 1/1 1.4115
1.075 29.9
-- -- -- -- 1.82/1
4 1/1.2 -- 1.075 28.5
-- -- -- -- --
at 29.degree.C
5 1/1.3 1.4200
1.08 28 -- -- -- -- 1.45/1
at 29.degree.C
6 1/1.5 1.4190
1.09 28 -- -- -- -- 1.35/1
7 1/2 1.4204
1.10 25.4
-- -- -- -- 1.1/1
8 1/3 1.4306
1.13 20.2
-- -- -- -- 0.82/1
Pro-
Postulated Structure
duct
("EtO") stands for
No.
ethoxy Proof of Structure
__________________________________________________________________________
HH The lack of absor-
.vertline..vertline.
bency peaks (or
1 (EtO).sub.3 --Si--OCCO--Si--(OEt).sub.3
troughs) in the IR
.vertline..vertline.
spectrograph in the
HH 2.7 micron region
Et indicates no (OH)
.vertline. group, hence sub-
HHO stantially all of
.vertline..vertline..vertline.
the glycol present
2 (EtO).sub.3 --Si--OCCO--Si--OEt
must be in the
.vertline..vertline..vertline.
backbone in the
HHO first two example
.vertline.
Et
3 82% backbone glycol 18%
herein. Silica
pendant glycol in poly-
content and hydro-
mer gen, oxygen and
carbon content all
support the postu-
4 Contains both backbone
lated structure
and pendant glycol
shown, as does al-
groupings in polymer
so the weight bal-
ance; and the IR
5 35% backbone glycol
NMR data indicate
65% pendant glycol
the ratios of back-
bone to pendant
6 35% backbone glycol
type glycol in my
65% pendant glycol
polymer that are
shown in the ad-
7 Some backbone glycol
joining column.
but predominantly
pendant glycol
8 Small amount of back-
*For explanation of
bone glycol but pre-
NMR date, see fol-
dominantly pendant
lowing.
glycol, some free gly-
col in the product
__________________________________________________________________________
*The area underneath the Nuclear Magnetic Resonance (NMR) signal peaks is directly proportional to the type of hydrogens contributing. When the peaks are integrated, one gets the number (or summation) of hydrogen types contributing to the peaks relative to others present. When integrated, one obtains a ratio of methylene to methyl to methine type hydrogens. The structure given and the ratio of backbone to pendant glycol in the table of various compositions correlate with the NMR results for the predicted composition based on relative charges, assumed reaction, amount of alcohol recovered during ester-exchange occurring and also were obtained, elemental analysis. The NMR of the -OH group in the pendant glycols, ##EQU11## fall in the range of frequencies 3.25 to 3.45 ppm (delta). The -OH peak is absent in the case of backbone glycol type structure. ##EQU12## The methylene in both the pendant and backbone glycol resonate in the same frequency region, and therefore cannot be used for differentiation. This is why the -OH is used to identify the pendant from the backbone glycol type. The -OH groups in Reagent Grade Glycol molecule (which is not bonded to the silicon atom) does not fall in this region. Solutions were in 15% deuterated chloroform and NEAT. While the structures of the reaction products of the polyol and monomeric silicate (e.g., tetraalkyl ortho silicate) are relatively simple, the polyol and polymeric alkyl and alkoxy alkyl silicate reaction products and mixed esters of these types are of relatively complex structure with larger molecules and many more reactive ester exchange sites. Therefore, bridging for the larger polymers as the extent of hydrolysis increases is thought to occur more easily because of the many sites available, and hence, to avoid excessive bridging with ultimate gelling of the products, more monomeric hydroxy compounds such as 2-ethoxy ethanol or alcohol may be necessary to compete for the sites on the silicon atom with the polyol, which, because the polyol is polyfunctional, tends to bridge, cross-link and polymerized, while the monomer hydroxy compounds inhibit and stop this reaction. It is, therefore, believed that as the polymeric silicate reactant is more highly hydrolyzed and more ester exchangeable sites are available for ester exchange reaction, in the presence of a large excess of monomeric hydroxy compounds, most of the polyol groupings are of the pendant type (not cross-linked) until the coating cures, due to alcohol or OH-compound removal upon which the hydroxyl groups of the polyol are cross-linked between silicon atoms present in the large molecules. This seems to be also true, for example, with the usual silicate reactants found in Ethyl Silicate 40, which is 40% hydrolyzed and has an average of about 5 silicon atoms per molecule and may have a broad distribution of monomeric, dimeric, trimeric, tetrameric, cyclic tetramer, cyclic pentamer, cross-linked hexamer, cross-linked heptamer-octamer-decamer, and so forth, to molecules having up to a maximum of about 16 silicon atoms per molecule. With highly hydrolyzed silicates, the cross-linked type structures occur have more of the silicon atoms being oxygen-bonded to a higher proportion of other silicon atoms as compared to oxygen bonded to organic radicals. The polyol silicate binders of the present invention can be made by a liquid phase, ester-exchange reaction between the polyol and the silicate, and during the reaction alcohol corresponding to the alcohol of the R groups, as defined above, i.e. ROH, is formed. Although the reaction may proceed to an acceptable extent without the removal of the alcohol from the reaction mixture, it is preferred, especially with the lower boiling products, to remove at least some or even a major portion, if not substantially all, of the low boiling alcohol formed and replace it with a higher boiling material to raise the flash point of the reaction mixture. If a single package product is desired, it is preferable to remove only enough of the alcohol to provide a stable product having a sufficiently high flash point. This may be a major portion of the alcohol formed. The alcohol can be removed by distillation after the reaction or during the reaction where the polyol reactant and alkoxy alkanol reactant have higher boiling points than the alcohol formed. It is most advantageous to remove a portion of the alcohol from the reaction mixture and replace it with an alkoxy alkanol, especially where the polyol-ortho silicate product is employed to form high flash point, single package metallic zinc-containing compositions. The extent of the alcohol removal from the reaction mixture may affect the molecular weight and gelling tendencies of the product since this removal can permit the cross-linking reaction to proceed. Generally, the ester-exchange is not allowed to be conducted to the extent that a solvent-insoluble product is obtained or gelling occurs when zinc dust is added to the product to form a paint, since this would make the polyol ortho silicate product virtually useless in coating compositions. It is preferred that the reaction be stopped well before the product is substantially gelled or will gel in contact with zinc dust, to the point of insolubility, although if gellation has not proceeded too far, the molecular weight, viscosity and tendencies of the product to gel may be reduced by the addition and reaction, e.g. by chain-termination, of alcohol back into the product. An example of this type of reaction for a monomeric silicate is as given below, and the general stabilizing or anti-gelling effect is observed to occur for higher siloxane polymers as well, and hence, this controls the tendency to gel or become objectionably viscous: ##EQU13## If excessive alcohol is present, the entire highly polymeric structure may be broken down. The reaction occurs more slowly at lower temperatures. The binder resulting from excess alcohol addition has a lower flash point and poorer properties in zinc-silicate coatings. Alkoxy alkanols as solvents are highly preferably to alcohols and it is highly advisable to have a minimum of low molecular weight alcohol in the binder as solvent both from a standpoint of flash point and cure rate of the zinc film. The presence of the alkoxy alkanol may counteract any undesirable result due to any alkanol in the product. The ester-exchange reaction employed to make the polyol silicate binders of this invention generally takes place at elevated temperatures, for instance, about 50.degree. or 80.degree. to 150.degree. or 160.degree.C., preferably about 90.degree. to 130.degree.C. The use of an ester-exchange catalyst may be necessary to obtain the desired reaction, and a small amount, e.g. a trace, or a relatively strongly acidic catalyst, for instance, having a dissociation constant at 25.degree.C. of at least about 0.001, such as sulfuric acid or hydrochloric acid, is highly preferred for the silicate-polyol reaction, especially when the latter does not contain nitrogen. After the exchange reaction, the acidic catalyst can be removed as by distillation, neutralization, reaction, adsorption on a filler, or ion exchange. In some instances, a separate catalyst may not be necessary, for example, when the polyol reactant contains a nitrogen atom, e.g. as with diethanol amine or triethanol amine, or when an alkoxy alkanol or another material present in the reaction mixture exerts a catalytic effect. For instance, if the reaction mixture contains a material having a carbonsilicon bond, e.g., alkyl trialkoxy silane, the reaction may proceed adequately in the absence of a separate catalyst, although the product is superior as a coating when acid is present. Other materials that may provide a catalytic effect are compounds which may participate in the ester-exchange reaction such as the alkyl titanates, e.g. butyl titanate or alkyl borates, aluminum alcoholates, but their use is not necessary and may not be advisable. The ester-exchange reaction system and the product may be essentially anhydrous, at least to the extent that insufficient water is present to cause the product to gel or cure to an essentially solvent-insoluble material. The presence of small amounts of water may not be unduly deleterious and may lead to partial hydrolysis of the product in situ. The polyol ortho silicate binder reaction products of this invention, exhibit substantial, and preferably essentially complete solubilty in, solvents for instance, methyl ethyl ketone, 2-ethoxy ethanol, and the like, and in some areas the products may react with this solvent on standing. The polyol ortho silicate binder reaction products of the present invention may be by other procedures, and these include an ester-exchange system involving the reaction of the ortho silicate, e.g. tetraalkyl ortho silicate, tetraalkoxyalkyl silicate mixtures thereof of tetra ortho silicates having both alkyl and alkoxy alkyl groups attached to the same silicon atom, with a larger amount of the polyol, for instance, by using a ratio of greater than 1.8, especially greater than 2 moles of hydroxyl group supplied by the polyol per mole of ester-exchangeable group in the ortho silicate reactant. Polymeric forms of these silicates may also be used as reactants in this procedure. This reaction produces a material which can be designated a silicon tetraglycollate in the case of reacting a monomeric silicate, i.e. Si(OMOH).sub.4 wherein M is the residue of the glycol. This intermediate can then be reacted with additional tetraalkyl or tetraalkoxyalkyl silicate or their polymeric forms to provide the polyol silicate reaction product of this invention. These reactions can be illustrated in simplified form as follows: ##EQU14## wherein R is ester-exchangeable alkyl, hydroxy alkyl of alkoxyalkyl of, say, up to about 4 or 7 carbon atoms, M is the glycol minus its 2 hydroxy groups, and x is 1 or more. The removal of the ROH drives the polymerization reaction more to completion, and when not removed, the glycol groups may be pendant. The overall ratio of polyol or ortho silicate reactants supplied to this system can be controlled by the amount of the reactants in the second reaction and to supply the desired ratio of polyol to ortho silicate as herein designated for making the reaction products of this invention. There can also be incorporated in the second reaction a variety of other reactants, e.g. polysilicates or silicone monomers and polymers, to make products useful in coatings. Also, various other reactants such as monohydroxy materials and polyols having at least 2 functional hydroxy groups per molecule of the types mentioned herein, can be present in the second reaction providing the overall ratio of polyol, monohydroxy reactant and ortho silicates are in the ratios set forth herein for my desired binder products. Generally, in the second reaction, the amount of the ortho silicate, e.g. (RO).sub.4 Si, present provides about 0.2 to 11 moles of ester-exchangeable group, per mole of functional hydroxy group in the intermediate silicate, e.g. Si(OMOH).sub.4, and preferably this amount is about 0.3 to 5:1 or even about 0.3 or 1.1 to 3:1. The initial reaction of ortho silicate may be conducted with excess polyol while optionally removing by distillation alcohol formed in the reaction, and optionally continuing this separation until the reaction mixture is in an essentially semisolid condition. Then, the additional ortho silicate can be added and reacted, optionally with further removal of alcohol by distillation, to prepare binder products of the present invention. These ester-exchange reactions can be conducted under the conditions disclosed herein for this type of reaction. The ester-exchange reaction by which my polyol silicate binder products are made, can be conducted in the absence of the addition of separate or extraneous solvent, although I prefer that at least some solvent be present before the reaction is completed in order to lower the viscosity of the product during the latter stages of the reaction, and to facilitate its handling and prevent its gelling in the presence of zinc. The polyol silicate binder is usually the bottoms or residual material in the reaction vessel at the conclusion of the ester-exchange, and all or a portion of any organic solvent added to the system may also be in the bottoms. When a solvent is employed during a reaction, it may often be present in amounts from about 5 to 400, preferably about 25 to 300, weight percent, based on the polyol silicate reaction product formed. The solvent may also be added to dilute the reaction product after the ester-exchange is complete, and this addition may be used alternatively or in conjunction with the addition of solvent before or during the reaction. Regardless of the time and manner of adding the solvent, it is advantageous to prepare a solvent solution of the polyol silicate binder for further handling or usage. Frequently, these solutions contain at least about 0.1 weight part of solvent per part of polyol silicate, and preferably about 0.5 to 10 weight parts of solvent per part of polyol silicate, including as solvent any alcohol present in the composition. While in some instances it may be preferable to remove some of any lower flash point alcohol formed in the ester-exchange reaction, removal of alcohol ether, e.g. alkoxy alkanol, formed in the ester-exchange is not as significant and its presence may be advantageous because of its higher flash Other info: Inventors: McLeod, Gordon D. (Adrian, MI, US) Application Number: 409067 Filing Date: 1973-10-24 Publication_date: 1976-01-13 Assignee: G. D. McLeod & Sons, Incorporated (Adrian, MI) Primary Class(es): 524/783 106/14.44, 524/780, 524/784, 524/785, 524/786, 524/791, 524/859, 524/863, 528/29, 528/425 Other Classes: US Patent Ref:
Other Refs: Primary Examiner: Jacobs, Lewis T. Assistant Examiner: Attorney: Morton, Bernard, Brown, Roberts & Sutherland |
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