IL35967A - Amide-aldehyde polymers containing zirconium or hafnium and process for their preparation - Google Patents

Description

35967/2 οη33π T"?nm ου.εη IN -maip-nj New amide-aldehyde polymers containing zirconium or hafnium and proeess for their preparation POLY-GHSM IHDUSTRIES, INC a preference for a higher coordination number of 6 to 8.

The increase in atomic size as well as the low number of d-electrons explain the pronounced tendency of zirconium and hafnium to react as electron acceptors whereby to form covalently bonded groupings with electron donors.

Both zirconium and hafnium react with halides to form compounds wherein the metal atom has a valence of four, e.g., ZrCl4, HfBr4. Such compounds represent the acid halides of the hypothetical amphoteric compounds, orthozirconic acid and orthohafnic acid. Anhydrides of the latter materials, referred to as zirconia, Zr02 and hafnia, HfO^, respectively, are typically three-dimensional polymeric structures, evidencing again the pronounced tendency of such materials to form covalent bonds with electron donors; correspondingly, such materials display a strong resistance to the formation of ions such as Zr+^ or Hf+4. Electron donor groups capable of covalent bond formation in the manner described can be unshared electron pairs such as characterizing elements of columns V and VI of the periodic table of elements. Thus, such materials will react with the orthoacids previously mentioned to form amides, alkoxides and thio-derivatives.

The products of the invention are prepared from polymerizable organic compounds containing more than one labile hydrogen atom in the presence of a zirconium or hafni halide, the preferred halides being zirconium tetrachloride and zirconium oxychloride. Hafnium tetrachloride, and hafnium oxychloride may also be used, but the noted zirconium chlorides are more readily available and less expensive. Th corresponding zirconium and hafnium bromides and iodides are also suitable for use in embodiments of the invention. The oxychlorides of zirconium and hafnium are conveniently prepared by hydrolysis of the tetrachloride.

The products of the invention are polymeric compositions having novel properties. It is believed that these properties , as well as the ease with which the products can be formed, are at least partly due to the incorporation of zirconium or hafnium into the polymeric structure. The products may be considered as being formed from zirconium or hafnium, and a polymerizable organic material containing at least two labile hydrogens, said material being capable of complexing, i.e., bonding with the zirconium or hafnium halide. Since the initial reaction results in the release of a hydrogen halide such as hydrogen chloride, for example, the result suggests that the reaction mechanism involves the replacement of the labile hydrogen witl. the metal of the metal halide to form a reactive metal complejf The metal complex then reacts further with the polymerizable compound or an added monomer to form the polymerized product. Typical labile hydrogen-containing groups include, without necessary limitation, -HNR, -OH, -SH, -H-XH or $-XH wherein X is 0 or S, etc., wherein R is alkyl, aryl or hydro tluLail irereiTP-rft«X i The labile hydrogen atoms are hydrogen atoms which are cleavable in connection with the formation of zirconium or hafnium complexes. The polymerizable organic compound is initially provided in low molecular weight form, e.g. monomeric form. which are recognized in the art can be categorized as follows I Condensation polymerization characterized by the elimination of a small, usually volatile molecule; II Addition polymerization of homonuclear Tf" -electron systems ; and III Addition polymerization of heteronuclear fj†-' -electron systems with donor molecules.

The aforementioned polymerization methods are, capable of providing polymers of various types, e.g., linear (thermoplastic), two-dimensional sheets or three-dimensional, thermosetting compositions including graft and block polymers and copolymers, depending, for example, upon the functionality of the reactants, i.e., the number and type of function al or "reactive" groups. Such techniques can be implemented in a variety of ways, e.g., simultaneously or sequentially, whereby to produce diverse types of highly useful compositions. Each of the aforedescribed polymer-forming systems, as well as hybrids thereof, can be employed to advantage in the practice of the present invention. This will be made clear by the following discussion, wherein each of such systems will be discussed separately.

I Condensation Polymerization Condensation polymerization is an illustrative aspect of the present invention and will be discussed first in some detail. Other polymerization techniques falling within the scope of the invention will be more readily understood by those skilled in the art in light of this discussion.

There are basically two types of condensation polymerization reactions. The first type, or complex condensation, involves the reaction of two dissimilar poly- propionaldehyde and furfural, with formaldehyde being most preferred.

In addition to the amide and aldehyde, there may be present one or more polyhydroxy compounds. The most suitable polyhydroxy compounds are (i) organic polymers bearing pendant hydroxy1 groups such as polyvinyl, alcohol; cellulose and derivatives thereof, including carboxymethyl-cellulose, hydroxyethyl cellulose; starches and modified derivatives thereof; etc., and (ii) polyhydroxy-benzenes , such as catechol, resorcinol, hydroquinone and pyrogallol . Polyhydroxy compounds are beneficial in improving the physical properties of the products and in minimizing shrinkage. The polyhydroxybenzenes can be used in amounts of about 0.01 to 1 moles per mole of amide, the preferred level being of the order of at least about 0.05 moles per mole of amide.

The amide/aldehyde reaction products, with or without added polyhydroxy compound, can be prepared by a number of different techniques, it being desirable that a substantially homogeneous reaction mixture is formed containing all of the desired reactants. Since the reaction is often rapid and exothermic, it is advisable to reserve one of the reactants, typically the aldehyde, and to prepare a blend of the remaining com onents. The reaction is then completed by rapidly mixing in the reserved component. The complete reaction mixture then rapidly polymerizes to a high molecular weight product.

The reaction is most conveniently carried out in the presence of water, although polymerization can also be conducted under essentially anhydrous conditions. The In practice, considerable quantities of water will generally be used, since the water facilitates blending of the reactants and also helps control the exotherm of the final reaction. The amount of water will typically be of the order of about 3 moles per mole of amide, and may be as high as 10 moles or as low as 0.3 moles. Any excess water will eventually be lost from the product by evaporation. The amount of water added will also affect the porosity of the final product and its specific gravity, greater amounts giving a more porous structure with larger, more numerous voids and lesser amounts giving a denser, less porous product .

The aldehyde will preferably be employed in amount sufficient to react with substantially all of the amide present as well as at least a portion of the polyhydroxy compound/ if used. However, considerably lesser or greater proportions can be used, if desired. The best physical properties are obtained when the aldehyde is present in the proportion of at least about one mole per mole of amide, with an additional one mole of aldehyde per mole of polyhydroxy compound, if any. An excess of the order of 10% of aldehyde is preferably provided to compensate for loss through volatilization. Larger excesses, even of the order of several hundred percent, can be used, since any unreacted aldehyde is lost by evaporation. The preferred aldehyde, is most conveniently added in the form of the commercially available 37% aqueous solution.

The zirconium or hafnium halide is generally employed in a proportion of between about 0.01 mole and 0.5 mole per mole of amide, and preferably between about 0.03 of the metal halide improve the gloss, luster and general appearance of the product, reduce cracking and reduce the rate of reaction. At very low metal levels, the products have a dull, opaque and somewhat chalky appearance. At higher levels, they become more glossy and smooth. At still higher levels, they are quite glossy and become translucent to transparent.

It has also been found advantageous to physical characteristics of the product to incorporate an organic, water-miscible solvent as part of the reaction mixture. Such solvents include N,N -dimethyl formamide, dioxane, lower alcohols, dimethyl sulfoxide, acetone, tetrahydrofuran , ethyl ene glycol, lower alkyl ethers of ethylene glycol or diethyl-ene glycol, etc. The solvent may contain reactive groups which are incorporated into the polymer product. Particularly advantageous solvents are aprotic solvents such as N,N -dimethyl formamide. The use of such solvents is especially desirable when water is not present or is present only in small quantities.

Where the amide employed has relatively low melting point, say below about 150°C, the following procedure has been found particularly useful. The zirconium or hafnium halide, in the form of the anhydrous tetrachloride, for example, is admixed with the amide and the resulting dry mixture is gently warmed until a uniform molten mass is obtained. The mixture will generally exhibit a somewhat depressed melting point. ' A portion of the water is then slowly added with stirring, and the resulting mixture is stirred at about 85°C to 100°C until substantially complete solution occurs. In order to obtain better heat transfer as glass beads can be added to the powder prior to melting. The addition of the inert solid particles results in better mixing of the reactants and a more homogeneous reaction mixture. In addition, the inert particles act as heat reservoirs which help prevent undesired fluctuations in temperature or local overheating. In some cases, the inert particles may be retained in the mixture when it is polymerized to serve as a filler or the like. Alternatively, the particles may be removed if desired by straining or decanting the fluid mixture. The resulting composition which is generally pale yellow and somewhat viscous, can be used immediately if desired. Where the amide used does not form a molten mixture with the metal chloride at a sufficiently low temperature, the metal chloride and amide can be initially mixed together in the presence of the water. In this instance, the metal chloride can be added in the form of the oxychloride, or the oxychloride can be generated in situ by the reaction of the tetrachloride and water.

It is known from the earlier work done by E. A.

Werner ("The Chemistry of Urea", Emile A. Werner, Longmans, Green & Co., of New York, 1923) that urea decomposes upon heating to cyanic acid and ammonia. Where the decomposition takes place in the presence of acid, the ammonium salt of the mineral acid is obtained. When urea is heated at or above its melting point subsequent reaction products are formed as a result of the instability and reactivity of cyanic acid. For example, cyanuric acid is produced by poly merization of cyanic acid while biuret arises from the inter action of cyanic acid and unchanged urea at temperatures ranging from about 135°C to about 190°C. Biuret however aqueous solutions even at low temperatures. Werner found that when urea is heated at a moderate rate to a temperature of about 180° for about 7 - 8 minutes the resulting mixture has the following compositions: H40C (in sublimate) 0.21% Biuret 24.50 Cyanuric Acid 5.93 Ammelide 3.9 Loss (NH3 + HCNO) 12.20 46.78% Unchanged urea (by difference) 53.22 A considerable amount of biuret, therefore is present in pyrolyzed urea. Continued pyrolysis of urea for longer periods results in a decrease in the concentration of biuret accompanied by the loss of ammonia due to the conversion of biuret to cyanuric acid and the stable compound ammelide. It is known from the work of F. L. Scott and H. 0. Smith (The Reaction of Urea with some amino - 1,3,5-triazines, Technical Report No. 17, Office Naval Research, 1960) that copyrolysis of urea or biuret with melamine and ammeline leads to the formation of 2-amino-4,6-diureido-l,3,5-triazine and 2-hydroxy-4 , 6-diureido-l, 3 , 5- triazine respectively. All of these nitrogen containing compounds, therefore, that is urea, cyanic acid, cyanuric acid, biuret and ammelide, can be essentially in a state of equilibrium in hot molten urea, the concentration of each compound in the mixture depending upon the temperature to which the urea is heated. In the practice of this invention, urea can be made to undergo similar reactions to provide a mixture of nitrogen containing compounds, the composition of which depends upon the temperature to which the mixture is heated. For convenience, such it will be understood that other components of the equili- j brium mixture, e.g. biuret, can also be employed as the initial compound. This mixture can further react or complex with the metal halide to give a metal complex composition which approximates the urea equilibrium mixture for the particular temperature range employed.

These pyrolyzed urea mixtures can, if desired, be preformed prior to the addition of the metal halide. Alternatively, they may be conveniently formed in the presence of the metal halide by simply melting together the urea and the metal halide, heating the molten mass to the desired temperature and holding it at that temperature for a sufficient time to achieve equilibrium. As a third alternative, the urea pyrolysis mixture may be formed and added to the polymerization mixture at some subsequent point, e.g. together with the aldehyde. Finally, any combination of the above techniques can be practised, as exemplified hereinafter.

In any of these techniques involving pyrolyzed urea, the properties of the final polymer can be varied in a predetermined manner by changing the temperature to which the initial urea mixture is heated in order to obtain the desired equilibrium mixture. For example, it has been found that a high proportion of biuret contributes to higher physical strength and hardness, better gloss, lower shrinkage and improved clarity in the final polymer. A similar desired balance of properties can be achieved either by pre-mixing urea and biuret in the proper proportions, or by starting with urea alone or biuret alone and heating it to the temperature at which the corresponding equilibrium mixture exists . products of the invention is to form a mixture of the water, amide, zirconium or hafnium halide, and to add the aldehyde thereto. Any solvent and polyhydroxy compound present can be admixed with either the aldehyde or the amide. Any polyhydroxybenzene or water-miscible solvent employed can be added to the amide-metal halide melt prior to, simultaneously with, or subsequent to the water. Other variations in the mixing steps are also possible, so long as a reasonable homogeneous mixture is obtained prior to the final reaction.

It has been found advantageous in the practice of a certain embodiment of the invention to reserve a portion of the amide and to add it subsequent to the formation of the amide-metal halide melt. Most conveniently, this reserved portion of the amide will be added simultaneously with the aldehyde. The amide can be any of the previously discussed materials, including the mixtures prepared by pyrolysis of urea, biuret, etc.

When an amide, typically urea, or a urea pyrolysis mixture is mixed with an aqueous solution of aldehyde, typically formaldehyde, the mixture may undergo undesirable changes with the passage of time. Low or high molecular weight condensation products may form and a heavy precipitate may deposit. It has been found that these amide-aldehyde compositions can be stabilized by the addition of small quantities of cyanuric acid, of the order of about 3% to about 25% based on the molar concentration of formaldehyde present. Analogs of cyanuric acid, such as ammeline and ammelide, can similarly be employed. Where relatively low amounts of cyanuric acid are used, the resulting solutions are generally cleai higher levels may result in some haziness or opacity, but any solids which deposit are readily redispersed. The addition of cyanuric acid to the polymer mixture also confers an additional improvement in the hardness and casting properties of the final product, and this occurs whether or not a portion of the amide is reserved and added with the formaldehyde. In any case, the cyanuric acid may be separately added as such or may be formed by pyrolysis of the amide used.

It has been found that a smoother, more controllable polymerization and improved physical properties are realized if the acidity of the polymerization mixture is substantially reduced prior to completing the polymerization. Although it is not intended to be bound by any particular theory, it appears that polymerization can occur by two distinct routes - the novel zirconium or hafnium-induced mechanism and the known acid-catalyzed condensation mechanism.

Removal of hydrogen ion would be expected to suppress the latter, and observations indicate that this is the case, since the exotherm is reduced dramatically and the product obtained has a harder, more glassy appearance, with improved hardness, gloss and clarity.

The acidity of the polymerization mixture can be appreciably reduced in a number of ways. For convenience, each of these techniques is generally practised upon the solution formed by the addition of water or other solvent to the molten amide-metal halide mixture. This solution is hereinafter referred to as the "hydrolyzed amide-metal halide reaction product". For example, some of the hydrogen halide may be removed by allowing the hydrolyzed amide-metal halide reaction product to stand or age at room l ed eratures f om several hours to several - 14 - 359 7 2 days. Hydrogen ion concentration can also be reduced by the additio of a base such as calcium hydroxide, calcium oxide, magnesium oxide, magnesium hydroxide, ethanolamine, sodium acetate or sodium tetraborate, for example. The hydrogen ion concentration can also be reduced through the use of any o the known ion exchange methods.

The preferred method of reducing the hydrogen ion concen^ tration, however, consists of introducing an oxidizing agent into the hydrolyzed amide-metal halide reaction product.

Any oxidizing agent which is capable of oxidizing the halide ion to the free halogen in the presence, of ¾he zirconium or hafnium halide may be employed* Oxidizing agents such as hydrogen peroxide, oxygen* ozone, air, sodium perborate and potassium peroxide are among the oxidizing agents which ca be employed. The oxid ation reaction may be represented as follows, wherein the hydrogen halide is hydrogen chloride and the oxidizing agent is hydrogen peroxide; 2H+ + 201*" + H2Q2 Δ C 2 f , + 2H20 The oxidation reaction is preferabl carried out at elevated temperatures. For example, where water is the solvent, the oxidation is preferably carried out at a temperature at or near the boiling point of the mixture. The use of agents such as sodium perborate in the oxidation step has the additional advantage of neutralizing some of the hydrogen halide to its corresponding metal salt. Hydrogen peroxide, oxygen, ozone and air are the preferred oxidizing agents since the use of such agents does not introduce oreign matter into the polymerization mixture which may discolor . or affect the h sical ro erties of the ol merizin roduct, ion can be carried put by allowing the hydrolyzed amide-metal halide reaction mixture to stand or age in contact with air. Although some of the halide ion escapes as hydrogen chloride during the aging process, aging also results in some air oxidation of the halide ion to the free halogen. The overall reaction may be represented as follows: 4H+ + 4C1" +02 →■ 2C12 f + 2H20 The rate of air oxidation or aging can be accelerated by bubbling air through the reaction mixture, preferably at elevated temperatures.

The rate of the oxidation reaction is dependent on the concentration of the metal complex and the oxidation does not proceed at a reasonable rate in the absence of the metal complex. Generally sufficient oxidizing agent is added to reduce considerably the concentration of hydrogen ion, as determined by standard acid-base titration techniques.

It has been found most convenient to express the acid concentration of the mixtures as a function of the amount of zirconium or hafnium* present , since various adjuvants and diluents which can be present would alter the absolute concentration. The standard unit of measurement which has been adopted for this purpose is the ratio of equivalents of titratable acid to moles of metal present in the sample.

The number of equivalents of titratable acid is determined by titrating an aliquot of the mixture with standard base, such as sodium hydroxide, to pH8. Since the number of moles ! of zirconium or hafnium present in the sample is known from the amounts of materials initially employed, the acid/ metal ratio is determined by simple calculation.

Any significant reduction in this acid ratio will r du eas l im rovem nt in the stren th inte rit and resistance to degradation on aging of the final product. However, the greatest improvements have been found when the acid ratio is reduced to a value of less than 1, preferably between about 0.5 and 0.75. The course of the oxidation can be followed simply by removing samples at various intervals, titrating them, and stopping the reaction at the desired point. Carrying the oxidation past the desired range may lead to solubility problems and difficulties in casting due to variations in viscosity. Since the preferred oxidizing agents, such as hydrogen peroxi' can be lost from a boiling reaction mixture without oxidizing the halide ion, it is best to follow the reaction by titratio: rather than merely adding a predetermined amount of oxidizing agent.

The oxidation reaction can be carried out over a range of temperatures, but it is preferred to carry it out at the highest convenient temperature, e. g. the boiling point of the mixture at atmospheric pressure, in order to achieve a rapid reaction rate and liberation of the free halogen which is formed.

It has also been found that the addition of concentrated sulfuric acid to the reaction mixture containing the metal complex will result in displacement of some of the dissolved hydrogen halide. In addition to reducing the halide ion concentration, however, the addition of sulfuric acid to the reaction mixture results in a polymer which is harder and glossier than the non-sulfated polymers. The sulfate ion appears to be bound within the polymer structure. Since it is known that zirconium has a strong affinity for sulfate ions and since no free sulfate ions were found in the polymerized product, the mechanism of the reaction probably involves the complexing of the sulfate ions with the polymerized product, resulting in a polymer having novel properties .

The final polymerized product is obtained by mixing together all of the desired reactants, including the solution containing the amide-metal complex, cooled to a temperature between room temperature and about 60°C, the aldehyde, preferably as a solution in water or a water-miscible solvent and any additional water desired, as well as any fillers, dyes, pigments or hydroxy1-containing polymers which are to be included. After a brief induction period polymerization generally takes place rapidly after the solutions are mixed.

Typically, polymerization will occur rapidly after the complete mixture has been formed. The mixture will remain fluid for several seconds, during which time it can be poured into a mold, extruded onto a moving surface or otherwise handled as desired. Within a very short period of time, typically a few minutes or less, the mixture will solidify and exhibit an exotherm. At this point, it can be handled and removed from the mold, although the development of physical properties will continue until the cure is complete and excess water has evaporated, typically, within a few hours. In preferred embodiments of the invention, particularly where polyhydroxybenzene compounds are included shrinkage is very low and the final product conforms closely to the contour and dimensions of the mold in which it was made.

Products of the invention show markedly different properties such as strength, shock resistance and heat - previously available. They typically possess high heat resistance and low flammability. In addition, they evolve little or no toxic gases when heated to high temperatures. Moreover, the polymerization can be extremely rapid and can be conducted in an aqueous system, if desired. Accordingly, the products of the invention can be employed in areas where previously known materials have been found unsatisfactory.

Aldehyde/polyhydroxybenzene systems are similarly prepared analogously to the amide/aldehyde systems. In this case, the polyhydroxybenzene compound is preferably admixed with water and the zirconium or hafnium chloride prior to the addition of the aldehyde. The useful polyhydroxybenzenes and aldehydes are as described above. Resorcinol and catecho form a molten mixture with zirconium tetrachloride at a sufficiently low temperature to permit them to be mixed together in the absence of water. Hydroquinone is more conveniently handled by dissolving it in water to facilitate mixing it with the metal chloride.

When the polyhydroxybenzene is resorcinol and the aldehyde is formaldehyde, polymerization occurs immediately upon the addition of the aldehyde with vigorous exotherm. When catechol or hydroquinone is used, there is a longer induction period, and mild heating may be desirable to initiate the reaction. The products obtained are typically hard, shock-resistant, solid materials.

Simple condensation polymerizations are those wherein a single polyfunctional compound is condensed with the zirconium or hafnium halide. Compounds of the formula , as previously defined, are included among the compounds ca able of under oin sim le condensation. T ical of such compounds are di- and trihydroxy compounds, dicarboxylic acids, diamides, lactams, etc.

Thus, polymer formation can result from the reaction of, for example, 2 moles of hexamethylene glycol with one mole of ZrCl4 by the splitting off of HC1 to produce a polymeric structure, such as: [-Zr - 0(CH2)6 0-]n The reaction of resorcinol with H^Br^ to form the following type of polymeric structure would likewise be typical : Further typical of the simple condensation polymerization mechanism is the product obtained by the interaction of zirconium halide with urea, such product conforming to structures such as : 0 I II -Zr-HN-C-NH- I These simple condensation products are, in addition to being useful per se as polymeric materials, also useful as pre-polymers or "building blocks" in complex condensation polymerizations.

II Addition Polymerization of Homonuclear Systems This particular system is analogous to those previously described and can be illustrated with reference to the reaction product of acrylamide with zirconium tetra-halide. This material, when subjected for example to peroxid initiated polymerization in the presence of one or more additional olefinic monomers copolymerizable therewith will yield three-dimensional polymeric products containing covalently-bonded zirconium. Λ similar result obtains with the reaction product of a zirconium halide with an ethyleni-cally unsaturated carboxylic acid, such as acrylic acid.

The addition polymerization systems are handled in a manner analogous to that described for the amide/aldehyde condensation systems. Thus an ethylenically unsaturated amide such as acrylamide, methacrylamide, 1-butene amide, etc. can be admixed with the zirconium or hafnium chloride, following the procedure previously described. The substantially 1 homogeneous solution formed from the unsaturated amide, the metal chloride and water is treated with a small amount - say 0.05 to 0.5 percent by weight, based on the weight of the amide - of a free radical initiator and the mixture is maintained at a temperature at which the initiator is active. Suitable free radical initiators include any of those employed in addition polymerizations, such as the alkali metal persulfates, t-butyl peroxide, benzoyl peroxide, t-butyl procrotonate and azo bis (isobutryronitrile) . If desired, the initiation temperature mayf be reduced by adding a suitable reducing agent such as sodium metabisulfite.

The polymers obtained are typically very high molecular weight, transparent, water-insoluble yellow solids. The polymer properties can be modified by the addition of an aldehyde, polyhydroxy compounds and fillers, as described above. Additionally, ethylenically unsaturated amide monomer can be admixed with other polymerizable monomers prior to the addition of the free radical initiator to produce novel copolymers. The properties obtained by polymerizing these monomers are quite different from those resulting from after-treatment of a pre-formed polymer.

Addition polymerization of ethylenically unsaturated carboxylic acid systems is handled in the same manner as the ethylenically unsaturated amide systems already described Suitable acids include acrylic acid, methacrylic acid, ethacrylic acid, 1-butenoic acid, etc. The polymers obtained are typically hard, yellow, transparent solids which exhibit some swelling when immersed in water, but do not dissolve.

A specific and unique form of carboxylic acid systems is the embodiment wherein a salt of a multivalent metal is incorporated for the purpose of occupying at least some of and preferably substantially all of the carboxylic acid groups which are not occupied by zirconium or hafnium. The term "multivalent metal" refers to a metal having a valence greater than 1. Suitable metals include calcium, magnesium, nickel, cobalt, zinc, aluminum, iron, copper, etc. These can be used in the form of any salt which renders the metal ion available to the carboxylic acid, such as oxides, hydroxides, carbonates, bicarbonates , nitrates, sulfates, chlorides, etc. The resulting polymers are exceptionally hard and strong and are suitable for use in structural devices . Where both carbonate or bicarbonate anion and a multivalent metal ion are provided, either from separate salts or as the multivalent metal carbonate or bicarbonate, the polymerization is accompanied by foaming to provide a low density, porous, hard material with high structural strength and shock resistance. Commercially available grouting and mortar cements which contain calcium sulfate and carbonates are suitable for use in this embodiment. The materials.

Ill Addition Polymerization of Heteronuclear Systems These systems can be illustrated with reference to the reaction product of ethylene glycol with zirconium tetrachloride. Reaction of the latter compound with a diisocyanate can result in formation of a three-dimensional zirconium-containing polyurethane. By way of contrast, a linear polyamide can result from the reaction of tetrakis (p-aminocatecholyl) zirconate derived from zirconium tetrachloride and p-aminocatechol with, for example, a diketene.

In addition to the foregoing, the invention includes hybrid systems wherein two or more of the above types of polymerization are carried out. For example, it is possible to react an amide, zirconium tetrachloride, an ethylenically unsaturated acid and a free radical initiator, with or without the addition of aldehyde, thereby obtaining a product wherein both addition and condensation polymerization has occurred.

The following representative examples illustrate practice of specific embodiments of the invention.

Example 1 In each of the following preparations, the same procedure is followed. A quantity of 9.0 gm. of urea is mixed with the noted amount of the noted metal chloride and the dry mixture is gently heated until melting occurs the temperature being maintained below 100°C. Then 3.0 ml. of distilled water is added with stirring and the mixture is heated below the boiling point and stirred for several minutes until a relatively uniform solution is obtained.

This solution is cooled to room temperature, 16 ml. of 37% formaldeh de solution (0.2 moles CI O) is added. The resulting solution is thoroughly blended and quickly poured into the bottom half of a petri dish having a diameter of about 3 inches and a depth of about 0.5 inch.

The reactant compositions are as follows.

Example Metal Chloride - Amount 1A ZrCl4 - 0.6 gm. (0.0026 mole) IB ZrCl4 - 1.2 gm. (0.0052 mole) 1C ZrC14 - 2· 4 gn (0.01 mole) ID A1C13.6H20 - 2.41 gm. (0.01 mole) IE A1(N03)3.9H2) - 3.75 gm. (0.01 mole) Examples 1A, IB and 1C, representing practice of the present invention, polymerize rapidly with a marked exotherm to give strong, solid, polymerized products within a period of a few minutes. Luster and hardness increase with increasing zirconium content, with Example 1C giving a glossy, lustrous plate with exceptional resistance to fracture .

Examples ID and IE, which represent typical Lewis acid-catalyzed polymerizations, polymerize more slowly than any of Examples 1A, IB and 1C. The products formed have a dry, chalky surface and are relatively brittle and fragile.

Example 1A is repeated, using molar equivalent amounts of magnesium chloride hexahydrate and zinc chloride in place of the zirconium tetrachloride. The magnesium chloride system is still liquid after 20 hours. The zinc chloride system does not solidify until after one hour and the product formed is dull, chalky, brittle and fragile.

Example 1C is repeated, substituting hafnium tetrachloride for zirconium tetrachloride. The results obtained are quite similar to those of Example 1C except that the product is somewhat less lustrous than that of Example 1C and has a few surface wrinkles.

Example 2 Following the procedure described in Example 1, the following systems are prepared: Examples Components 2A 25 gm. melamine, 2.5 gm. zirconium tetrachloride, 7.5 ml. water, 24 ml. formaldehyde (37%) 2B 17 gm. acetamide, 4 gm. zirconium tetrachloride, 4 ml. water, 30 ml. formaldehyde (37%) Example 2A produces a hard, milk white opaque polymer. Example 2B produces a yellow, transparent polymer.

Example 3 A quantity of 6.0 gm. of urea is admixed with 2.0 gm. zirconium tetrachloride and the resulting dry mixture is gently warmed until molten, after which 4.0 ml. of water is added and the mixture is stirred and warmed until dissolved. In a separate vessel, 5.0 gm. of high molecular weight, fully hydrolyzed polyvinyl alcohol is slurried in 20 ml. of 37% formaldehyde and the slurry is poured into the urea-containing solution. The mixture is quickly stirred and poured into a petri dish base. After a very brief induction period, a strong exotherm is observed and the mixture polymerizes rapidly to a white, translucent solid plate. The fully-cured product is hard and highly resistant to breakage. Example 4 Following the procedure of Example 3, the following are prepared: Example Components 4A 11.4 gm. thiourea, 0.6 gm. zirconium tetrachloride, 3.0 ml. water, 16.0 ml. formaldehyde, 2 gm. polyvinyl alcohol Example Components 4B AS in 4A except that a molar equivalent amount of quanidine hydrochloride replaces the thiourea.

Example 4A initially produces a gel which passes through a rubbery state and finally to a hard, brittle, translucent solid. Example 4B passes from a gel to a slightly yellow rubbery material with high tensile strength. Example 5 A mixture of 18.0 gm. of urea, 2.5 gm. of resorcinol, 3.0 gm. of zirconium tetrachloride and 8 ml. of water is stirred with heating until a uniform dispersion is obtained. The mixture is then cooled to room temperature and the noted amount of each of the following aldehydes is added: mple Aldehyde - Amount 5A formaldehyde - 35 ml. (0.43 mole) 5B acetaldehyde - 19 ml. (0.43 mole) 5C propionaldehyde - 25 ml. (0.43 mole) 5D furfural - 41 gm. (0.43 mole) Each of the resulting mixtures is thoroughly stirred and poured quickly into a petri dish mold. Example 5A quickly polymerizes with a strong exotherm to give a hard, strong polymer which exhibited little shrinkage.

Examples 5B and 5C produce tacky, yellow polymers exhibiting marked adhesive properties. Example 5D produces a very strong exotherm and yields a hard, black polymer with high shock resistance.

Example 6 A mixture of 90.0 gm. of urea, 16.5 gm. of resorcinol and 23.0 gm. of zirconium tetrachloride is gently warmed until a uniform molten mass is obtained. A mixture of 10 ml. of water and 25 ml. of Ν,Ν-dimethyl formamide is added and stirred until a uniform dispersion is obtained. The mixture is cooled to room temperature and 175 ml. of 37% formaldehyde is added and rapidly mixed in. When poured into a mold, the mixture polymerizes smoothly and quickly to give a hard, strong polymer with little shrinkage.

Example 7 A mixture of 16.5 gm. of resorcinol and 1.5 gm. of zirconium tetrachloride is gently warmed until molten, after which 4.0 ml. of water is added and stirred in until a uniform dispersion is formed. The dispersion is cooled and 16.0 ml. of 37% formaldehyde is added. A very strong exother occurs and a pink-to-red hard polymer is quickly formed.

Example 8 A mixture of 7.1 gm. of acrylamide and 3.0 gm. of zirconium tetrachloride is gently warmed until molten.

A quantity of 3.0 ml. of water is added. The resulting solution is cooled and 3 drops of t-butyl procrotonate are added. The solution gels almost immediately and rapidly polymerizes with a strong exotherm to a tenacious, yellow polymer.

Example 9 * A mixture of 7 gm. of acrylic acid and 1 gm. of zirconium tetrachloride is warmed gently until molten and 3 ml. of water is added. The resulting solution is cooled and 3 drops of t-butyl procrotonate are added.

The mixture polymerizes rapidly to give a hard, brittle, amber resin which swells but does not dissolve in water.

Example 10 To 14 ml. of a 50% aqueous solution of acrylic acid, - of 7 gm. of mortar cement containing calcium sulfate and calcium carbonate, and 0.3 gm. of t-butyl procrotonate .

The mixture rapidly foams and forms a hard, strong porous structure suitable for use as a structural material.

Example 11 A mixture of 6.0 gm. of urea and 2.3 gm. of zirconium tetrachloride is gently heated until molten, and 5 ml. of water is added. The resulting slightly viscous syrup is cooled to room temperature, 7 ml. of acrylic acid is dissolved therein and a mixture of about 0.2 gm. of ammonium persulfate and 0.1 gm. sodium thiosulfate is added as a free radical initiator. The mixture rapidly polymerizes with foaming to produce a white, porous, flexible material.

Example 12 The procedure of Example 11 is! repeated with 12 ml. of 37% formaldehyde replacing the 5 ml. of water. A hard, rigid, white, opaque polymeric composition is formed.

Example 13 A mixture is prepared from 40 ml. of bis (2-meth-oxyethyl) ether, 4.6 gm. of zirconium tetrachloride, 15.2 gm. urea and 24 ml. of furfural. The mixture polymerizes to a porous, black, resinous material.

Example 14 A mixture is prepared from 24 gm. of urea, 23.3 gm. of zirconium tetrachloride, 22 gm. of resorcinol and 30 ml. of bis (2-methoxyethyl) ether. The mixture polymerizes to a rigid, tacky, yellow-brown material which is insoluble in water and acetone. I Example 15 A mixture of 36gm. of urea and 9.6gm. of zirconium tetrachloride is added to a solution of 18ml. of 37% formaldehyde, 18ml. of phenol and 10ml. of water. The resulting mixture is heated at 90 °C for at least 30 minutes then cooled to room temperature to give a tan, opaque fluid. A suspension of 12gm. of polyvinyl alcohol (90-98% hydrolyzed polyvinyl acetate) in 78ml. of 37% formaldehyde is added and the resulting mixture polymerizes readily and smoothly to give a hard, lustrous, glossy polymer. By admixing the phenol and a portion of the formaldehyde in the manner indicated, the exotherm normally associated with the use of hydroxybenzenes is controlled.

Example 16 .0gm. of urea is mixed with 14.45gm. of zirconium tetrachloride and the dry mixture is gently heated to about 150°C. Water (25ml.) is added to the molten solution with stirring and the mixture is heated to boiling. A 3% aqueous solution of hydrogen peroxide is added dropwise to the hot solution with stirring. One milliliter aliquots are removed at intervals and titrated with IN aqueous sodium hydroxide to pH8 in order to determine the hydrogen ion concentration. The addition of peroxide is continued until the titratable acid ratio is 0.75. 48gm. of urea is heated for 20 minutes at 170 - 175 °C, after which the melt is removed from the heat and placed in a water bath; the melt solidifies. 112ml. of 37% formaldehyde solution (1.4 moles) and cyanuric acid (25.8gm.) are mixed together and the mixture is heated at 50-60 °C with stirring until a clear solution is obtained. The formaldehydehyde and the mixture is heated at about 50 °C with stirring until solution occurs. The resulting solution is then poured into the urea-zirconium solution; the mixture is blended and quickly poured into the bottom half of a petri dish.

The mixture polymerizes to a white, solid plate. The above reaction can be carried out in the absence of hydrogen peroxide; the polymer thus obtained tends to discolor and is more brittle.

Example 17 a) 30.25gm. of biuret is added to 14.45gm. of zirconium tetrachloride. The powders are mixed together and the mixture is heated to about 150 °C. The resulting melt is removed from the heat and 30ml. of water is added. The mixture is heated to boiling and 3% hydrogen peroxide solution is added dropwise to the boiling solution with stirring. One milliliter aliquots are removed at intervals and titrated with IN aqueous sodium hydroxide in order to determine the hydrogen ion concentration. The addition of peroxide is continued until the titratable acid ratio is 0.75. 6gm. of urea is added to the oxidized solution and the mixture is warmed to 40 °C. b) 48gm. of urea is heated to 170 °C and the melt is heated at this temperature for 20 minutes. The melt is allowed to cool to a hard solid. A mixture of 112ml. of 37% formaldehyde solution and 16.77gm. of cyanuric acid is heated with stirring until a clear solution is obtained. The formaldehyde solution and the urea residue are mixed together and the mixture is heated at about 50 °C until complete solution occurs. The resulting mixture and the urea mixture formed in a) above are heated to 60 °C and then blended to 155mm. x 15mm. A white, solid polymer is obtained.

Example 18 a) 15.0gm. of urea and 14.4gm. of zirconium tetrachloride are mixed together and the mixture is heated to 150°C. The resulting melt is removed from the heat and 30ml. of water is added. The mixture is then heated to boiling and 3% hydrogen peroxide solution is added dropwise to the boiling solution with stirring. One milliliter aliquots are removed at intervals and titrated with IN aqueous sodium hydroxide to a pH of 8. The addition of peroxide is continued until the titratable acid ratio is 0.75. 21gm. of urea is added and the mixture heated at 40 °C until a clear solution is obtained. The solution is then cooled to room temperature. b) Biuret (41gm.) is added to 112ml. of 37% formaldehyde solution with stirring and the mixture is heated to 75-80°C, after which it is cooled to room temperature. The biuret-formaldehyde mixture is added to the urea mixture formed in a) above; the resulting mixture is blended quickly and then poured into a 9 oz. plastic cup mold. A very white, solid forms on standing which exhibits little shrinkage. , Example 19 24gm. of urea and 22gm. of resorcinol are mixed with 14.4gm. of zirconium tetrachloride. 10ml. of water is added to the mixture. After the evolution of gas subsides, 7ml. of concentrated sulfuric acid are added dropwise to the solution at room temperature. The addition of sulfuric acid results in an exothermic reaction with the evolution of hydrogen chloride. After the addition of acid is complete, the solution is heated to 180°F, after which the temperature is allowed to return to room temperature. 72ml. of 37% formaldehyde is added to the urea complex and the resulting mixture is blended and poured into a mold. Polymerization occurs rapidly resulting in a pink polymer which exhibits little shrinkage and shows no decomposition after standing for 10 months. No decomposition or cracking is observed upon immersing the polymer in water for 48 hours.

Example 20 A mixture of 15.0gm. of urea and 14.4gm. of zirconium tetrachloride is heated to 150 °C. The resulting melt is removed from the heat and 25ml. of water is added. The mixture is then heated to boiling and 3% hydrogen peroxide is added dropwise to the boiling solution with stirring. One milliliter aliquots are removed at intervals and titrated with IN aqueous sodium hydroxide to a pH of 8. The addition of peroxide is continued until the titratabl acid ratio is 1.0. 15gm. of urea is added and the mixture is heated at 40 °C until the urea is dissolved. b) A mixture of 112ml. of 37% formaldehyde solution, 25.2gm. of melamine and 18gm. of urea is heated to 60 °C until solution occurs, and the; 'solution is then cooled to room temperature. The cool solution is added to the solution prepared in a) above with stirring and the mixture is poured into a 5 oz. plastic cup. The mixture solidifies as a hard, glossy translucent material, which becomes transparent after standing at room temperature for several days .

As will be understood by those skilled in the art, many variations and modifications can be made in the scope of the invention.

Claims (22)

35967/3 I "CLAIMS ■ ·· -- - .j

1. An amide-aldehyde polymer wherein said polymer ; is derived from an amide (as herein defined) containing at least two labile hydrogens; said polymer containing therein zirconium j or hafnium in a concentijation of at least about 0.01 mole to one mole of amide.

2. A polymer of claim 1 which comprises the reaction product of at least one amide (as herein defined) having at least two labile hydrogens; a zirconium or hafnium halide at a concen- tration at least about 0.01 mole of said halide to one mole of ! said amide;w ter; and at least one aldehyde. !

3. A polymer of claim 2 wherein the proportioh ■"··■ of water to amide is between about 0.3 moles to about 10 moles. :[

4. A polymer of claim 3 which comprises the reaction jj product of: ■ ,j , i (a) a product formed by the admixture of said amide ,j i ' with said halide, wherein water is added before >j or subsequent to the formation of the me al- amide product; with , ι

• 5. The polymer of claim 4 wherein in step (a) said amide-and said halide are heated together before ; ! ' addition of water. *

6. The polymer of claims 4 or 5 wherein the acidity of the product from step (a) is reduced. | 1 , ■l ■

7. The polymer of claims 4-6 wherein the amide ■ j . is selected from the group consisting of urea biuret,' > \ Ί ' ari'd mixtures thereof. j

8. The polymer of claims 4-7 wherei said halide ■j'* is zirconium tetrachloride or zirconium oxychloride.

9. The polymer of claims 4-8 wherein said aldehyde is selected from the group consisting of aliphatic, alicyclic or heterocyclic aldehydes.

10. The polymer of claim 9 wherein said aldehyde is formaldehyde, acetaldehyde, propionaldehyde or furfural.

11. The polymer of claim 10 wherein said aldehyde is formaldehyde.

12. The polymer of claim 6 wherein said amide is urea, said aldehyde is formaldehyde, said halide is zirconium tetrachloride; the mole ratio of halide to amide is. between 0.03 and 0.3, £ d the mole ratio of water to · amide is about 3.0 moles to 1.0. ,

13.. The polymer of claim 12 wherein there is present at least 0.05 moles of a polyhydroxy compound per mole of amide.

14. The polymer of claim 13 wherein said polyhydroxy compound ia poly ydroxy-bonzone .

15. The polymer of claim 14 wherein said polyhydroxy benzene is selected from the group consisting of hydroquinone , catechol, resorcinol, pyrogallol and mixtures thereof.

16. A process for preparing an amide-aldehyde . polymer which comprises the steps of: ; (a) admixing a metal halide selected from , the group consisting of zirconium halide or hafnium halide with at least one amide (ao herein definod) haying at least two labile hydrogens to form an amide-metal product, water being added before or subsequent to the formation of the amide-metal product; and (b) contacting said product with at least one alfehyde . 35967/2 Ψ

17· The process of Claim 16 wherein the acidity of the product from step {a) is reduced.

18. The process of claim 16 wherein said aldehyde is selected from the group consisting of aliphatic, alicyclic, heterocyclic aldehydes or mixtures thereof said amide is selected from the group consisting of urea, biuret, and mixtures thereof; said metal halide is a zirconium halide; the mole ratio of said water to said amide is about 0.3 to about 10; and the mole ratio of said metal halide to said amide is about 0.01 to about 0.5·

19. ^ e process of claim 18 wherein said aldehyde is formaldehyde; said amide is urea or a mixture of urea and melamine; and a polyhydroxy compound is added to step (a).

20. The process of claim 19 wherei the acidity of the product from step (a) is reduced.

21. The process of claims 16-20 wherein the admixed metal halide and amide of step (a) is heated before addition of water.

22. The process of claims 16-21 wherein there is admixed wit the product of ste (a) solid, inert, insoluble particles.