Clear terpolymers

April 1, 1958 r. j. slocombe etal 2,829,128

CLEAR TERPOLYMERS

Filed Dec. 7, 1953 ⁸ Sheets-Sheet 1

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FIG. T st vrene/acrylomitrile /diethyl. funiarate TERPOlYiaers \\|T. °lo

ROBERT J. SLOCOMBE GEORG&gt;E L. WESP,

INVENTORS

BY

R. J. SLOCOMBE ET AL 2,829,128

CLEAR TERPOLYMERS

Sheets-Sheet 2

April 1, 1958

Filed Dec. 7. 1953

<img file="US2829128A_D0002.tif" />

FIG.ir

STYRENE /ACRYLONITRILE/METUYL \vt. %

METHACRYLATE TERPOLYMERS

ROBERT J. SLOCOMBE

GEORGE L. VESR

INVENTORS»

BY

R. J. SLOCOMBE ET AL 2,829,128

CLEAR TERPOLYMERS

Sheets-Sheet 3

April 1, 1958

Filed Dec. 7, 1953

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i FVG.TSI.

STYRENE/acRYLON|T(?ILe/meTHYL VINYL KETONE TERPOLYMERS

WT.^o

ROBERT J. SLOCOMBE GEORGE L. WESP .

INVENTORS

BY

R. J. SLOCOMBE ETAL 2,829,128

CLEAR TERPOLYMERS

Sheets-Sheet 4

April 1, 1958

Filed Dec. 7, 1953

<img file="US2829128A_D0004.tif" />

FIG.TSZ7

STYRENE / ACRYLONITRILE / METHACRYLONITRILE TERPOLYMERS

WT. */o ' ROBERT J. SLOCOMBE

GEORGE L.WESP,

INVENTORS

BY

R. J. SLOCOMBE ET AL

CLEAR TERPOLYMERS

2,829,128

April 1, 1958

Filed Dec. 7, 1953

Sheets-Sheet 5

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BY

April 1, 1958 r. j. slocqmbe etal 2,829,128

CLEAR TERPOLYMERS

Filed Dec. 7, 1953 8 Sheets-Sheet 6

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April 1, 1958 r. j. slocombe et al 2,829,128

CLEAR TERPOLYMERS

Filed Dec. 7, 1953 8 Sheets-Sheet 7

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April 1, 1958 r. j. slocombe etal 2,829,128

CLEAR TERPOLYMERS

Filed Dec. 7, 1953 8 Sheets-Sheet 8

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BY

United States Patent Office _Patented

2,829,128

CLEAR TERPOLYMERS 5

Robert J. Slocombe, Dayton, and George L. Wesp, Englewood, Ohio, assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware

Application December 7,1953, Serial No. 396,506 10

Claims. (CI. 260—78.5)

This invention relates to three-component interpoly- 15 mers, commonly called terpolymers, i, e., interpolymere prepared by polymerizing a monomeric mixture consisting of three different monomers. In specific aspects the invention pertains to terpolymers of (a) a monomer selected from the group consisting of styrene, vinyltoluene, ²⁰and vinylxylene, (6) acrylonitrile, and (c) a monomer selected from the group consisting of dialkyl fumarate, methacrylic acid, methacrylonitrile, alkyl methacrylate, methyl vinyl ketone, monoalkyl fumarate, and monoalkyl maleate. Other aspects of the invention relate to ²⁵improved methods of preparing clear terpolymers.

It is by now well known that ethylenically unsaturated monomers differ greatly in their polymerization reactivity toward each other. There are in fact some monomers that will not undergo homopolymerization at all, i. e., ³⁰polymerization of two or more molecules of the same monomer to form a polymer of that monomer, yet will readily undergo interpolymerization with certain other monomers. In terpolymerization affords a method of imparting varying characteristics to a polymer, and in ³⁰many instances such characteristics cannot be obtained by mere physical admixture of two or more homopolymers. However, because of the above-mentioned differences in reactivity among monomers toward each other, marked heterogeneity is the rule in interpolymere and ⁴⁰only under special circumstances can an interpolymer be obtained that is of sufficient homogeneity to give a transparent or clear interpolymer. While some objectionable properties such as color, encountered in interpolymers, _4gcan often be avoided by means such as the use of stabilizers or lower polymerization temperatures, incompatibility manifested by haze, turbidity, or opacity in plastics is not overcome by such treatment.

If a monomeric mixture is subjected to polymerization _eoand the initial increment of polymer is segregated before the polymerization is allowed to go forward to an appreciable extent, it is frequently possible to obtain a clear interpolymer, but the commercial impracticability of such a procedure is apparent. On the other hand, if 55 polymerization is permitted to proceed to a considerable and especially to a high degree of conversion, the more reactive monomer enters into the polymer to a greater extent than a less reactive monomer or monomers with the consequence that residual unreacted monomer be- go comes more and more depleted in the more reactive monomer, while the polymer being formed in the latter stages of polymerization is deficient in the more reactive monomer. There results a polymeric material which is made up of a variety of polymer molecules running g5 a gamut of compositions such that the total polymer is heterogeneous with resultant opacity and often greatly impaired physical properties. This phenomenon, resulting in an undesirable product, can be overcome to an appreciable but limited extent by gradully adding during 70 the course of the polymerization the more reactive monomer at a rate aimed at keeping the composition of un2 reacted monomeric mixture essentially constant. As a practical matter it is extremely difficult to approach uniformity in such an operation, and it is impossible to use this technique at all in the case of mass (bulk) polymerization in which the polymerization reaction mixture sets up into semi-solid or solid polymer after the reaction is only partly completed so that further access of added monomer to the total mixture cannot be obtained.

It is only in recent years that systematic laboratory and theoretical studies of interpolymerization have gone forward sufficiently to permit a certain amount of predictability in this field. It has been theorized that in a simple binary system involving the free-radical-initiated polymerization of only two monomers, the composition of polymer will be dependent only upon the rate of four propagation steps, i. e., steps in the propagation of polymer molecules. Thus, taking a system involving two monomers, Mj and M₂, a growing polymer chain can have only two kinds of active terminal groups, i. e., a group derived from Μχ or a group derived from M₂Either of these groups has the possibility of reacting with either Mj or with M₂. Using mp and m₂- to indicate these active terminal groups, the four possible reactions are as follows:

<td> Growing chain</td><td> Adding monomer</td><td> Rate of progress</td><td> Reaction product</td>

<td> ——mv —7771· —*—m2· '—m2·</td><td> Mi M2 M₂ Mi</td><td> Aii[wp] [Mi ftl2[Wl·] [M2 &amp;22[m2 ·] [M2 foiiw] [Afi]</td><td> —77717771· —77117712· —77727772· —77727771·</td>

Theoretical considerations lead to the now generally accepted copolymer composition equation which describes the ratio

[MJ

[MJ of the molar concentrations of two monomers in the initial copolymer formed from a given mixture of the monomers as follows:

d[MJ [MJ rJMJ+[M₂] d[M₂} [MJ r₂[MJ+[MJ

In this equation equals kn/ki₂ and r₂ equals k₂₂/k_2i. The terms iq and r₂ are called “reactivity ratios.” A very considerable body of experimental work has in general confirmed the copolymer composition equation.

A large proportion of possible pairs of monomers are incapable, because of their respective reactivity ratios, of forming under any conditions an instantaneous polymer having the same composition as the monomeric mixture from which it is formed. However there are certain monomer pairs which, in a proportion characteristic of that pair, give a copolymer having the same composition as the particular monomeric mixture. In such instances, a batch polymerization can be carried out with a monomeric mixture of the particular composition with a resultant homogeneous copolymer containing the same relative proportions of the monomers as in the initial monomeric reaction mixture. This composition is known as the polymerization azeotrope composition, and is represented by the equation:

[MJ _n-i

[MJ r₂—1

Such an azeotrope composition can exist only for those monomer pairs wherein both and r₂ are less than one, or theoretically wherein both and r₂ are greater than one although no examples of the latter combination are known.

While an understanding of interpolymerization involving only two monomers is now possible to a considerable

3,820,128 extent, because of the development of the above-discussed theories, an increase in the number of monomers to three or more obviously tremendously increases the possibilities and complications. Thus, for example if interpolymers of 100 monomers are to he considered, there are about 5000 possible monomer pairs, but aboutl60,000 different combinations of three monomers are possible, and for each of these 160,000 combinations the variations in relative proportions of three monomers are infinite. If the assumptions made in the development of the copolymer composition equation still hold true where three monomers are to be interpolymerized, it is apparent that the composition of the terpolymers formed at any given instance will now be dependent upon the rate of nine propagation steps which are dependent upon the relative concentrations of the monomers in the monomeric mixture and the reactivity ratio between each of the pairs of the monomers in the mixture. It has been pointed out that the study of terpolymers can be simplified somewhat by application of the copolymer composition equation, suitably modified for three-component systems, so as to eliminate from consideration monomers whose ability to interpolymerize is so slight that further investigation of such combinations is obviously not warranted. However, the discovery of terpolymers having particularly desired physical properties has to the present time been limited to the “needle in the haystack” type of investigation. There is an obvious need for some procedure in the terpolymer field whereby terpolymers of particular properties can be made with a reasonable degree of predictability.

In accordance with the present invention, we have found a group of terpolymers that can be made by freeradical-initiated batch polymerization and that have the very desirable property of clarity. These terpolymers are made by polymerizing a monomeric mixture of certain proportions of three monomers. The proportions giving clear terpolymers will vary from one monomeric mixture to another depending upon the particular monomers present in that mixture. The invention is particularly applied to monomeric mixtures consisting essentially of (a) a monomer selected from the group consisting of styrene, vinyltoluene, and vinylxylene, (Z&gt;) acrylonitrile, and (c) a monomer selected from the group consisting of dialkyl fumarate, methacrylic acid, methacrylonitrile, alkyl methacrylate, methyl vinyl ketone, monoalkyl fumarate, and monoalkyl maleate. For example, a monomeric mixture consisting of styrene, acrylonitrile and methyl methacrylate will, when subjected to free-radical-initiated batch polymerization, give a clear terpolymer only if the relative proportions of styrene, acrylonitrile and methyl methacrylate are properly chosen in a manner to be hereinafter described. In contrast, a monomeric mixture consisting of styrene, acrylonitrile and methacrylonitrile will give a clear terpolymer on being subjected to freeradical-initiated batch polymerization only if the relative proportions of the three mentioned monomers in the monomeric mixture are within certain limits which in general are different from those of the aforementioned mixtures of styrene, acrylonitrile and methyl methacrylate, and yet which are chosen in accordance with the same principle now to be discussed.

We have found that clear terpolymers of the nature described are made provided the proportions of three monomers in the monomeric mixture are chosen from the area lying along the line joining the binary polymerization azeotrope composition of the particular (a) and acrylonitrile on one hand, and the binary polymerization azeotrope composition of the particular (a) and the particular (c) on the other hand, as plotted on a triangular' coordinate graph. By way of example, taking the case where (a) is styrene and (c) is methyl methacrylate, the point of the binary azeotrope composition of styrene and acrylonitrile is placed along one side of a triangular coordinate graph at the proper location between the apex designating 100 percent styrene and the apex designating 100 percent acrylonitrile. This point is 76 to 77 weight percent styrene and 24 to 23 weight percent acrylonitrile. On the opposite side of the equilateral triangle, constituting the triangular coordinate graph, is placed the point representing the binary azeotrope composition of styrene and methyl methacrylate, this of course being located at the proper position on the side of the triangle between the apex representing 100 percent styrene and the apex representing 100 percent methyl methacrylate. This point is 54 weight percent styrene and 46 weight percent methyl methacrylate. Now a straight line is drawn between these two points. This line cuts across the triangular coordinate graph, without touching the side of the triangle opposite the styrene apex which side represents varying proportions of acrylonitrile and methyl methacrylate in binary mixtures of same. Acrylonitrile and methyl methacrylate do not form a binary azeotrope. The said straight line joining the two points of binary azeotrope compositions describes three-component monomeric mixtures which, when subjected to free-radical-initiated batch polymerization, give clear terpolymers. Further, there is an appreciable area lying on each side of said line in which the terpolymers are essentially clear. However, one cannot go too far from this line without producing terpolymers which are not clear but range from hazy to opaque materials. The invention particularly applies to the area lying within 5 percent on each side of said line; said 5 percent is measured on the graph in a direction normal to the line, and is equal to five onehundredths of the shortest distance between an apex and the side of the triangle opposite that apex. (Another way of saying the same thing is that the invention particularly applies to the area of the graph bounded by two lines on opposite sides of and parallel to and 5 graphical units distant from said line.) Terpolymers made by polymerizing a monomeric mixture having a composition lying in the area within 5 percent on each side of the line joining the two binary polymerization azeotrope compositions, are generally clearer than polymers made from similar monomeric mixtures lying farther away from and on the same side of the line. In most systems all terpolymers made from monomeric mixtures having compositions in the area lying within 5 percent on each side of the line are clear. In some systems the area of clarity may not extend as far as 5 percent from the line. Those skilled in the art, having had the benefit of the present disclosure, can easily determine by simple tests of the nature described herein which monomeric mixtures give clear terpolymers in a gixen polymerization system. In all events, the compositions of monomeric mixtures giving clear terpolymers will be found to constitute an area lying along and encompassing the line joining the two binary polymerization azeotrope compositions.

The reasons for the clarity of terpolymers made as described are not known. The line joining the two binary azeotrope compositions does not represent what might be called a series of three-component azeotropes. From much detailed data which we have obtained, the relative proportions of the three monomers in terpolymers made from monomeric mixtures lying along said line are not identical to the monomeric mixture from which rhe terpolymer is being prepared. In other words, during the course of a batch polymerization of a monomeric mixture whose composition is taken from the line, the composition of residual monomeric material drifts and the terpolymers so formed are not homogeneous mixtures of polymer molecules all of which contain monomer units in the same ratio, but rather arc mixtures of polymer molecules having varying proportions of the three monomer units therein. No heretofore known scientific facts or theories of interpolymerization explain our discovery. However, regardless of the various reasons for believing that terpolymers made from compositions lying along the line as aforesaid would be heterogeneous, and regardless

2,829,128 system styrene/acrylonisystem styrene/acrylonisystem styrene/acrylonisystem vinylxylene/acrysystem styrene/acrylonistyrene/acrylonistyrene/acryloni- .

of the actual reasons for the clarity of such terpolymers, it is apparent that the present invention makes possible the production of clear terpolymers with obvious attendant advantages, especially in films and molded articles made from the terpolymers.

The accompanying drawings are triangular coordinate graphs showing compositions of some three-component monomeric mixtures that give clear terpolymers on being subjected to free-radical-initiated batch polymerization.

Figure I represents the system styrene/acrylonitrile/diethyl fumarate.

Figure II represents the trile/methyl methacrylate.

Figure III represents the trile/methyl vinyl ketone.

Figure IV represents the trile/methacrylonitrile.

Figure V represents the lonitrile/methyl methacrylate.

Figure VI represents the trile/monoethyl maleate.

Figure VII represents the system trile/normal-butyl methacrylate.

Figure VIII represents the system trile/isopropyl methacrylate.

By the present invention we can subject a given mono meric mixture consisting of three monomers, selected as described herein, to a batch polymerization and carry the polymerization reaction to complete or essentially complete, say 90 to .100 percent, conversion of all of the monomers and yet obtain a clear solid resinous terpolymer. If desired, the polymerization can be stopped at any point short of completion so long as polymerization conditions are such as to produce solid terpolymer, but this is not necessary in order to obtain a clear terpolymer and would seldom be advantageous. The'higher the degree of conversion of monomeric mixtures, the greater the advantages of our invention. This is because the greatest extent of heterogeneity is found with complete conversion to polymers. A high conversion, i. e., at least 50 weight percent conversion and preferably at least 80 weight percent conversion, is preferred in practicing the invention. However, some of the benefits of the invention may be realized even where the percentage conversion is as low as 20 percent. With very low conversions, the polymer formed tends to approach the perfect homogeneity existing in the first infinitely small increment of polymer formed. As pointed out above, commercial practicality requires that conversion be carried to a value more than a few percent, hence introducing the lack of homogeneity which up to now, the art has not known how to avoid other than by techniques such as gradual monomer addition. It is to be recognized that the extent of the area of clear terpolymers, lying along the line joining the two binary polymerization azeotrope compositions, is dependent not only on the particular polymerization system but also on the percentage conversion, said area being the greater the lower the percentage conversion, and the smaller the higher the percentage conversion. It is observed that the terpolymers become clearer as the composition of the monomeric mixture approaches the line joining the two binary azeotrope compositions, the general rule being that the clearest terpolymers are those derived from monomeric compositions lying on the line.

It is usually desirable that the three-component monomeric mixture contain at least 2 weight percent, and preferably at least 5 weight percent, of the monomer present in the smallest amount.

The invention is broadly applicable to any free-radical-initiated interpolymerization of three-component monomeric mixtures containing the monomer combinations and in the proportions set forth herein, provided the polymerization is carried out by a batch procedure. By this it is meant that all of the monomeric materials to be '

... ......... .... . 6........ . . ' employed are introduced simultaneously in the desited proportions into the polymerization reaction system. Ordinarily a single charge of monomeric materials will be placed in a reaction vessel and the single charge subjected to polymerization conditions until the polymerization is substantially complete. However, it is not outside the scope of our invention to introduce continuously a monomeric mixture containing the three monomers in fixed proportions into a flow-type polymerization system, whereby the initial polymerizable mixture passes away from its point of introduction and ultimately is recovered as polymer. This can be accomplished by continuous flowing of the monomeric mixture into the first of a series of polymerization reaction vessels with continuous flow of reaction mixture from one vessel to another along a series of two or more such vessels with ultimate recovery of polymer from the last in the series. Those skilled in the art will understand that this operation is essentially a batch operation in the sense that additional monomeric material of composition different from the original mixture is not introduced into a partially polymerized material. Thus, the term “batch polymerization,” as used herein, means a polymerization which does not involve the gradual or incremental or subsequent addition of a monomer or monomers having a composition different from the initial monomeric mixture.

This invention is perhaps most advantageously effected by the mass or bulk polymerization procedure. In such procedure the reaction mixture is free from added solvent or other reaction medium and consists solely of monomers, resultant polymers, and catalyst and regulator, if any. An important advantage of the invention is that such a mass polymerization can be effected to produce a clear terpolymer in a situation in which it is impossible to use the gradual monomer addition technique discussed above.

If desired, the interpolymers of the present invention can be made by the suspension or the emulsion polymerization techniques. For suspension polymerization a reaction medium such as water is used together with a small amount of suspending agent, for example tricalcium phosphate, carboxymethylcellulose, etc., to give a suspension of particles of initial monomeric mixture, which particles are not of such small size as to result in a permanently stable latex. Where the particles are of quite large size, this type of polymerization is often called pearl polymerization. To effect emulsion polymerization, sufficient amount of emulsifying agent, for example a water-soluble salt of a sulfonated long chain alkyl aromatic compound, a surface active condensation product of ethylene oxide with long chain aliphatic alcohols or mercaptans, etc., is employed along with vigorous agitation whereby an emulsion of the reactants in water is formed and the product is obtained in the form of a latex. The latex can then be coagulated if desired by known methods and the polymer separated from the water. For some applications the latex can be employed directly as for example for forming a film, and the resulting film after evaporation of the water will be clear when the polymers are made in accordance with the present invention. The emulsion technique has certain advantages particularly in that a very high degree conversion of the monomers is obtained with considerable rapidity, since the heat of reaction is easily carried off by indirect heat exchange with the reaction mixture which contains a considerable proportion of water. Such polymerizations are often effected with redox-type catalyst systems at moderate temperatures of say 60° C on down to 0 ° C. and below.

The polymers of the present invention can also be made in the presence of an added organic solvent. It should be recognized however that the presence of such a solvent ordinarily results in a polymer of lower molecular weight than that obtained in the absence of the solvent.

2,85

Conventional recipes and procedures for effecting mass, solvent, suspension and emulsion polymerizations are : so well-known to those skilled in the art, that they need not be further detailed here.

From the foregoing, it will be apparent that the term, “monomeric mixture,” as used in the claims refers only to the polymerizable monomeric materials used in the process, and that additionally solvents, aqueous reaction media, catalysts, etc., can be present or not in the reaction mixture as may be desired in any particular case. In other words, in the claims “monomeric mixture” is not necessarily synonymous with “reaction mixture.”

Polymerization can be effected by any of the wellknown free radical mechanisms. The polymerization is initiated and carried on by virtue of free radicals, which can be derived from the monomers themselves on simple heating of the monomeric mixture to a suitable temperature, or can be derived from added free-radical-supplying catalysts, especially the “per” compounds and the “azo” compounds, or can be derived by ultra-violet or other irradiation of the reaction mixture with or without the presence of photosensitizers, e. g., organic disulfides. The examples set forth hereinafter describe “thermal” polymerizations in which the polymerization reaction was initiated and maintained merely by heating ²⁵the monomeric mixture in the absence of any added catalyst. In many instances it will be desired to add a suitable polymerization catalyst, in which case sufficient catalyst is employed to give a desired reaction rate. Suitable catalysts are of the free-radical-promoting type, principal among which are peroxide-type polymerization catalysts, and azo-type polymerization catalysts. Those skilled in the art are now fully familiar with a large number of peroxide-type polymerization catalysts and a suitable one can readily be chosen by simple trial. Such catalysts can be inorganic or organic, the latter having the general formula: R'OOR, wherein R' is an organic radical and R is an organic radical or hydrogen. These compounds are broadly termed peroxides, and in a more specific sense are hydroperoxides when R is hydrogen. R' and R can be hydrocarbon radicals or organic radicals substituted with a great variety of substituents. By way of example, suitable peroxide-type catalysts include benzoyl peroxide, ditertiary butyl peroxide, tertiary butyl _ hydroperoxide, diacetyl peroxide, diethyl peroxycarbonate, 2-phenyl propane-2-hydroperoxide (known also as cumene hydroperoxide) among the organic peroxides; hydrogen peroxide, potassium persulfate, perborates and other “per” compounds among the inorganic peroxides. The azo-type polymerization catalysts are also well-known '' to those skilled in the art. These are characterized by the presence in the molecule of the group —N=N— bonded to one or two organic radicals, preferably at least one of the bonds being to a tertiary carbon atom. By way of example of suitable azo-type catalysts can be mentioned α,α'-azodiisobutyronitrile, p-bromobenzenediazonium fluoborate, N-nitroso-p-bromoacetanilide, azomethane, phenyldiazonium halides, diazoaminobenzene, p-bromobenzenediazonium hydroxide, p-tolyldiazoamino- θθ benzene. The peroxy-type or azo-type polymerization catalyst is used in small but catalytic amounts, which are generally not in excess of one percent by weight based upon the monomeric material. A suitable quantity is often in the range of 0.05 to 0.5 percent by weight. ₀Photopolymerization is another suitable procedure for carrying out the present invention. This is ordinarily accomplished by irradiating the reaction mixture with ultraviolet light. Any suitable source of light is employed having effective amounts of light with wave lengths -q of 2,000 to 4,000 Angstrom units. The vessel in which the polymerization is conducted should be transparent to light of the desired wave length so that the light can pass through the sides of the container. Suitable glasses are available commercially and include borosilicate 75

9,12s (“Pyrex”), “Vycor,” and soft glass. Alternatively, the source of light can be placed directly over the surface of the monomer in a container or can be placed within the reaction mixture itself. In some instances it is helpfl ful to add a material that can be termed a photosensitizer, i. e., a material which increases the rate of photopolymerization, for example organic disulfides as described in U. S. Patent No. 2,460,105.

Choice of a suitable temperature for a given poly10 merization will readily be made by those skilled in the art having been given the benefit of the present disclosure. In general, suitable temperatures will be found within the range of 0° C. to 200° C., although temperatures outside this range are not beyond the scope of 15 the invention in its broadest aspects. The time required for complete polymerization will depend not only upon the temperature but also upon the catalyst if any is employed, the ability of the system to remove heat of polymerization, and the particular monomers employed. 20 The examples set forth hereinafter give some illustrative information as to reaction times for particular polymerizations.

The term “triangular coordinate graph” as used herein is well understood. The accompanying figures are examples of such graphs and the use of same. However, for the sake of completeness the following statement can be made concerning the character of such triangular graphs. The graph is an equilateral triangle, divided off by three series of parallel lines each series being 30. parallel to one side of the triangle. The distance between an apex of the triangle and the side opposite that apex represents variations in percentages of the component designated by that apex varying from 100 percent to 0 percent in equal increments running from the apex 35 to the opposite side of the triangle. For example, if the distande between the apex and the side of the triangle opposite the apex is divided into 100 equal parts by lines passing across the triangle and parallel to said side, each line represents 1 percent of the component for which that apex is designated. Thus, any point within the triangle represents a single three-component composition, the indicated percentages of the three components totaling 100 percent.

As an aid in the choice of suitable proportions of monomers for polymerization in accordance with the invention the following data on reactivity ratios of certain monomer pairs are presented by way of example. The values given are considered the best ones represented in the literature or otherwise known (see “Copolymers,” by Alfrey, Bohrer and Mark, Interscience Publishers, Inc., 1952, pp. 32-43). In many instances an attempt is made to set forth an approximate order of accuracy. These latter figures, expressed as plus or minus certain values, should not however be given too much credence since such attempts to evaluate possible errors are dependent to a considerable extent on subjective evaluation of the data. Most of the values for reactivity ratios given are for moderate temperatures, say between about room temperature (20° C.) and 100° C. Of course, the value of the reactivity ratios for a monomer pair is a function of temperature but the variation in reactivity ratios with temperature is quite small and is of little importance unless the polymerization is to be carried out at temperatures considerably removed from those mentioned. Likewise, the reactivity ratios given are for atmospheric or autogenous pressure. Only if the polymerization pressure is to be quite considerably increased will there be an important change in the value of the reactivity ratios. It may also be pointed out that in the case of highly watersoluble monomers the reactivity ratio values may be shifted somewhat from those given, when polymerization is effected in an aqueous system. Those skilled in the art, having been given the benefit of the present disclosure, will be able to evaluate the effect, if any, of

2,829,138 reaction conditions on the values given herein and determine the extent of such effect. Similarly, those skilled in the art can determine by well-known procedures the correct reactivity ratios for monomer pairs not specifically set forth in the following tabulation, which tabulation is given by way of example of some but not all of the monomers that are the subject matter of the present invention.

In the following tabulation styrene is considered as

Mj and the other monomers in each instance are con- 10 sidered as M₂. Substitution of the values for i\ and r₂in the equation given above for the binary polymerization azeotrope composition permits an immediate determination of the proper location for the two points to be placed on the triangular coordinate graph, between 15 tions can be which points is drawn the line of clear terpolymers.

TABLE

<td> Mi</td><td> Mi</td><td> ri</td><td> ri</td>

<td> Styrene_____</td><td> Acrylonitrile._______________</td><td> 0.41 ±0.08</td><td> 0.03 ±0.03</td>

<td> Do_____</td><td> Diethyl fumarate___________</td><td> 0.30 ±0.02</td><td> 0.07 ±0.007</td>

<td> Do_____</td><td> Dimethyl fumarate_________</td><td> 0.21 ±0.02</td><td> 0.025±0.015</td>

<td> Do_____</td><td> Methacrylic acid____________</td><td> 0.16 ±0.01</td><td> 0.7 ±0.05</td>

<td> Do_____</td><td> Methacrylonitrile___________</td><td> 0.30 ±0.10</td><td> 0.16 ±0.06</td>

<td> Do_____</td><td> Methyl methacrylate_______</td><td> 0.520±0.026</td><td> 0.460±0.026</td>

<td> Do_____</td><td> Methyl vinyl ketone_____...</td><td> 0.29 ±0.04</td><td> 0.35 ±0.02</td>

<td> Do_____</td><td> Mono'ethyl fumarate________</td><td> 0.18 ±0.10</td><td> 0.25 ±0.10</td>

<td> Do_____</td><td> Monoethyl maleate.________</td><td> 0.13 ±0.01</td><td> 0.035±0.01</td>

Where M_t is to be vinyltoluene or vinylxylene, the same reactivity ratios are used, on the assumption that the reactivity ratios for such systems do not differ essentially for the purposes of this invention from the reactivity ratios of the corresponding systems wherein styrene is Mi. This assumes that the introduction of one or two methyl groups into the aromatic nucleus of styrene does not greatly alter the polarity and steric properties of the vinyl double bond. Likewise, when an alkyl methacrylate other than methyl methacrylate is to Ire used, the reactivity ratios are assumed not to differ essentially for the purposes of this invention from the above reactivity ratios involving methyl methacrylate. This assumes that a moderate increase in the chain length of the alkyl group in the alkyl methacrylates over the single carbon atom in the methyl group of methyl methacrylate, or a branching of the chain if such is present, does not greatly alter the polarity and steric properties of the vinyl double bond. Similar assumptions are made with respect to the various dialkyl fumarates as a group, with respect to the various monoalkyl fumarates as a group, and with respect to the various monoalkyl maleates as a group. Thus, although the reactivity ratios for styrene/dimethyl fumarate and for styrene/diethyl fumarate appear to differ considerably from each other, the values of the binary azeotrope compositions for these two systems calculated from said different reactivity ratios, given in the table above, differ from each other by only two percentage points. Anyone skilled in the art, desiring greater precision, can use well-known standard procedures to determine the reactivity ratios for a given binary system not previously reported in the art. With monomers having fairly long chain alkyl groups, the reactivity ratios tend to differ considerably from those for the corresponding methyl monomer and hence should be individually determined. Whenever weight percent rather than mole percent is desired as a matter of convenience, mole percentages of the binary azeotrope compositions are easily converted to weight percent by use of the molecular weights of the particular Mi and M₃. In the case of dialkyl fumarates, alky! methacrylates, monoalkyl fumarates, and monoalkyl maleates, any of which can be copolymerized with acrylonitrile and any one of the monomers styrene, vinyltoluene, and vinylxylene in the practice of this invention, special preference is given to the lower alkyl groups. Alkyl groups containing from 1 to 4 carbon io atoms are particularly valuable, viz., methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl, tertbutyl. However, the invention is also applicable to the alkyl compounds mentioned, that contain alkyl groups 5 of up to 8 carbon atoms per alkyl group and even higher. In the case of dialkyl fumarates, there are included those dialkyl fumarates wherein both alkyl groups are the same and those dialkyl fumarates wherein two different alkyl groups are present in the molecule.

The following examples illustrate some methods for practicing the present invention with respect to certain ternary mixtures of monomers. The general applicability of the invention, and advantages thereof, are shown in these examples. It will be appreciated that variamade in the particular choice of monomers, proportions, and methods of polymerization in accordance with the general teachings of the present specification, and the examples are not to be taken as coextensive with the invention in its broadest aspects.

Example 1

This example concerns the ternary system styrene/acrylonitrile/diethyl fumarate. The data obtained in this example are set forth graphically in Figure I of the drawings.

The composition of the styrene/diethyl fumarate binary azeotrope was calculated in the following manner according to the article by Mayo and Walling, Chemical Reviews, 46, 199 (1950). The value of 0.08 used for r₂ is the average of two values given in that article.

Styrene (Mi)

Diethyl fumarate (M₂) n=0.30 ³⁵ r₂=0.08

[Mi] 0.08—1 -0.92

[M₂] 0.30-1 -0.70^-1’⁰

[MJ-|-[M₂]=100 ⁴⁰ 1.3[M₂]+[M₂] = 100=2.3[M₂]

[M₂]=43.4 mole percent diethyl fumarate

[Mi]=56.6 mole percent styrene

Molecular weight of diethyl fumarate =172.2 ⁴⁵ Molecular weight of styrene —104.1

0.434X172.2 = 74.8 grams diethyl fumarate 0.566X104.1= 58.8 grams styrene

133.6 grams mixture ⁵⁰ (74.8X 100)/133.6=56 weight percent diethyl fumarate (58.8X100)/133.6=44 weight percent styrene

The foregoing calculations give the compositions of the styrene/diethyl fumarate binary polymerization, azeo⁵⁵ trope as 44 weight percent styrene, 56 weight percent diethyl fumarate.

By the same procedure, the binary polymerization azeotrope for styrene/acrylonitrile was calculated to be 77 weight percent styrene, 23 weight percent acrylo66 nitrile, using slightly different reactivity ratio values than in the examples following.

A series of monomeric mixtures was made up, each mixture being prepared by admixture of the individual pure monomers in a “Pyrex” test tube 150 mm. long 65 and having an internal diameter within the approximate range of 14 to 18 mm., usually about 16 mm. Each test tube containing the particular monomeric mixture was flushed with nitrogen in order to remove any air present in the gas space above the liquid, and the test 70 tube was then sealed off at the top by heating the tube under nitrogen and pulling it out in the flame to seal the tube completely. Each particular monomer mixture was prepared and polymerized in duplicate.

After the various tubes containing the monomeric mix75 tures had been prepared, they were placed in a 90’ C.

2.829,128 .constant temperature bath, and held there for -24 hours. At the end of that period they were moved to a 120° C. constant temperature bath and held there for 24 hours. At the end of this second 24-hour period the tubes were removed and placed in an oven maintained at 180° C., and held therein for 8 hours.

The various monomeric compositions are set forth in detail in Table I. Table I designates each different mixture by sample number. Sample No. 1 is the binary styrene/acrylonitrile azeotrope composition. Sample No. 6 is the binary styrene/diethyl fumarate azeotrope composition. Samples 2, 3, 4, and 5 have compositions which fall on a straight line connecting the two binary azeotrope compositions, designated samples Nos. 1 and 6, when ploted on triangular coordinates. See Figure I.

Samples 7 to 20, inclusive, were prepared with compositions which varied so that several series of two or three different compositions running along constant diethyl fumarate composition lines and cutting across the line joining the two binary azeotropes could be examined.

At the end of the polymerization cycle described above, all the polymers formed in the sealed tubes were carefully examined visually by the same observer, looking through the diameter of the cylindrical body of polymer obtained by breaking and removing the glass tube; this cylinder of polymer conformed to the internal shape and showed a sparkling appearance as found in high quality crystal glassware.

Several of the polymer products were analyzed for nitrogen and the acrylonitrile content of the polymer 5 calculated. In each instance it was close to the acrylonitrile content of the monomeric mixture, but consistently ran slightly low, which the literature states is the uniform experience in nitrogen determinations on polymers.

The alcohol solubles content of many of the polymers 10 was determined, using the following standard procedure:

A 0.3 gram-sample of polymer is dissolved in 20 mJ. acetone (or other suitable solvent), then the polymer is precipitated by adding 250 ml. absolute ethanol to the solution; the precipitate is coagulated, filtered off, dried 15 and weighed. The average of two determinations is given. The alcohol solubles content (ASC) gives an approximate measure of the extent of conversion. The material soluble in alcohol is principally monomer; only very low molecular weight polymers, e. g., dimers and trimers, are 20 soluble in alcohol. Thus, 100—ASC approximates the percentage conversion.

The specific viscosity was determined on the total polymer, and on the undissolved residue from the alcohol solubles test. The specific viscosity determinations were 25 made on a 0.1 weight percent solution of polymer in dimethylformamide.

TABLE I

STYRENE/AGRYLONITRILE/DIETHYL FUMARATE TERPOLYMERS

Composition,

Sample weight

No. percent,

DEF/AN/S

Clarity

Appearance

Color

Percent AN* in polymer

Alcohol solubles content, weight percent

Specific viscosity

Total Inso]polym. uble alcohol residue

2...., 3_____

4_____

5_____

6_____

8.-? 0_____

10.... 11.... 12....

13— 14.... 15.... 16..-. 17....

18....

19..., 20.—

0/23/77 5/21/74 15/17/68 25/13/62 35/ 9/56 56/ 0/44

5/39/65 5/25/70 5/17/78 15/25/60 15/20/65 15/14/71 25/15/60 25/10/G5 35/11/54 35/ 7/58 35/ 5/60 45/ 7/48 45/ 5/50 45/ 3/52

C—Clear..................

_____do...................

.....do.___________________ —do_____________________ _____do____________________ —.do____________________

H—Hazy—......

C—Clear.—......

O—Opaque.......-.......

H—-Hazy.________________

C—Clear (si. hazy)________ _____do____________________ C—Clear-----------------_____do__________________ ...-.do.-..-—........——

...._do____________________ _____do____________________ _____do-.............-...... ...—do....... ______do....................

Colorless..............

do._..............

_____do... ____________ _____do________________ V. si. yellow._________

Colorless..-____________

Yellow______—........

V. si. yellow........—.

White_________________

Yellow_______________

SI. yellow.._______....

Colorless..—..........

V. si. yellow__________

Colorless.—...........

Light yellow————— Colorless______________ _____do________________ Light yellow...-......

V. si. yellow__________

Colorless—.___________

11.7 14.1

9.2 8.9

C.138 0.158

0.116 0.128

DEF=diethyl fumaiate; AN=acrylonitrile; S=styrene; SI.-slightly; V. slavery slightly.

*=calculated from nitrogen analysis.

size of the glass tube. These visual observations were checked by other observers. It was determined that the clarity noted for polymer samples is not significantly affected by variation in polymer cylinder diameter within the range of about 14 to 18 millimeters. It is to be understood that where clarity of polymers is discussed herein, reference is made to the appearance on looking through a cylindrical body of the polymer having a diameter within the approximate range of 14 to 18 millimeters. The following words were adopted for describing the clarity of polymers.

C—Clear: essentially crystal clear

H—Hazy: some cloudiness but slight

T—Turbid: moderately cloudy

O—Opaque: dense cloudiness, similar to milk glass in appearance “Clear” means relatively free from gross amounts of haze but allows the presence of slight haze to be detected with close examination in strong light. Specific notation that a sample was “crystal” clear means not only that no haze was apparent to the observer, but also that the sample

Referring now to Fig. I of the drawings, the clarity data given in Table I have been designated alongside each of the corresponding ternary monomeric mixture composition indicated by a point on a triangular coordinate plot.. The various numerals on Fig. I located adjacent 60 the respective points refer to the sample number in Table

I. All of the points marked “C” were rated as clear, and of these all were crystal clear with the exception of points 11 and 12, each of which had a slight haze but not sufficient to consider them other than essentially clear or 65 to bring them from the clear rating into the hazy rating.

Examination of Fig. I immediately shows that terpolymers prepared from monomeric mixtures having compositions lying on the line joining the two binary azeotrope compositions were clear, as were terpolymers within the 70 area lying along said line. However, going appreciably beyond 5 percent on each side of the line the terpolymers become non-clear. Thus, points 7 and 10 were hazy and point 9 was opaque. It is interesting to note that points 7 and 10 below the line are about 10 percent away from 75 the line and yet only hazy, whereas point 9 above the line is about 7 percent away from the line and yet is

2,8 opaque. Such behavior is consistent with most physical phenomena which seldom exhibit perfect regularity. The data in the present example demonstrate that terpolymers made from ternary monomeric mixtures whose composition is taken from along the line and from a significant area lying on each side of the line are clear, and also that polymers falling within the area within 5 percent of each side of the line constitute a new group of terpolymers having the extremely important property of clarity.

Another interesting thing to note is that by the practice of the present invention terpolymers of minimum color ordinarily result. Thus, polymers 7 and 10 of those tested, farthest away from the line were yellow, While the color decreased as the line was approached. All those polymers lying below the line had at least a trace of yellow color but the color intensity decreased as the line was approached. Those above the line had no color, other than point 9 which was white and opaque.

In Fig. I the dashed lines drawn parallel to the line joining the two binary azeotrope compositions are 5 percent on each side of the line, i. e., each is a distance from the line equal to 5 percentage points of composition as determined by dividing the distance between an apex and the center of the opposite side of the triangle into 100 equal equidistance parts; in other words, the two dashed lines arc on opposite sides of and 5 graphical units distant from said line.

Example 2

This example presents data oh the ternary system styrene/acrylonitrile/methyl methacrylate.

Considering styrene as Mj and methyl methacrylate as M₂, the reactivity ratios are ^=0.52 and r₂=0.46. From these data, in the manner set forth in Example 1, the binary polymerization azeotrope composition of styrene/methyl methacrylate was calculated to be 54 weight percent styrene and 46 weight percent methyl methacrylate. The composition for the styrene/acrylonitrile binary polymerization azeotrope composition ^: was calculated to be 24 weight percent acrylonitrile, 76 weight percent, styrene.

Samples containing varying proportions of the monomers were prepared and polymerized and observations made on the polymers in the manner described in Example 1. The data are listed in Table II and plotted in Fig. II of the drawings. Samples 1—14 were run first. Samples 15, 16 and 17 and a repeat on sample 13 were run later and with a different batch of monomers, Which explains the fact that somewhat lighter yellow colors were obtained than would be expected from the colors of samples 12 and 13.

TABLE II

STYRENE/ACRYLONITRILE/METHYL METHACRYLATE TERPOLYMERS

<td rowspan="2"> Sample No.</td><td rowspan="2"> Compo- sltion, weight percent, MMA/S/AN</td><td colspan="2"> Appearance</td><td rowspan="2"> Weight percent alcohol solubles content</td><td rowspan="2"> Specific viscosity, total polymer 60</td>

<td> Clarity</td><td> Color</td>

<td> 1.......</td><td rowspan="19"> 0/76/24 5/74/21 15/69/16 25/64/11 35/59/ 6 46/54/ 0 ’ 5/78/17 10/80/10 20/75/ 5 35/63/ 2 5/70/25 10/65/25 25/55/20 35/55/10 25/55/20 17/59/24 41/42/17 35/37/28</td><td rowspan="19"> C—Clear.___ _____do___;____ .....do___.... .....do....... _____do....... .'—.do___.... O—Opaque. _____do....... .....do....... C—Clear.... _____do_______ .....do....... —..do....·... _____do_______ .....do_______ _____do....... _____do....... O—Opaque.</td><td rowspan="7"> Colorless.... _____do....... ____.do....... .....do_______ .....do_______ —do....... White_______</td><td rowspan="15"> 3.41 3.71. 4.12 4.93 5.06 2.86 3.92. 3.66 2.70 2.94 2.56 4.80 6.03 5.18</td><td rowspan="15"> 0.199 0.178 0.153 0.137 0.136 °·¹⁰³0.158 65 0.122 • 0.101 0.102 0.202 0.202 0.177 ₇n 0.141 ‘^υ</td>

<td> 2—.....</td>

<td> 3.______</td>

<td> 4—</td>

<td> 5-..___</td>

<td> 6.______</td>

<td> 7-______</td>

<td> 8—.</td><td rowspan="6"> .....do_______ ____.do.______ Colorless.— V. 1. yellow (si. yellow). L. yellow... Yellow:______</td>

<td> 9_______</td>

<td> 10______</td>

<td> 11______</td>

<td> 12______</td>

<td> 13-. —</td>

<td> 14.___—</td><td rowspan="2"> Colorless— SI. yellow___</td>

<td> 13.....</td>

<td> 15_____.</td><td rowspan="2"> —’do....... L. yellow___</td><td rowspan="2"> —</td><td rowspan="2"> —</td>

<td> 16</td>

<td> 17</td><td> ____Zdo -</td><td></td><td></td>

<td></td><td></td><td></td><td></td>

MMA=methyl methacrylate; S=styrene; AN=acrylonitrile. 75 »,128

The data of. Table II, particularly, as plotted on Fig. II, again show the clarity of terpolymers preparedfrom monomeric mixtures, whose, composition is taken from the line joining the two binary poymerization azeotrope 5 compositions. Further, polymers made from compositions taken at a considerable distance on each side of the line are likewise clear. As in Example 1 with the styren/acrylonitrile/diethyl fumarate terpolymers, Opacity increases more quickly above the line as higher concen10 trations of styrene are approached than it does below the line. Thus, in the present system styrene/acrylonitrile/methyl methacrylate, point 7, which is essentially on the 5 percent line, is opaque, so that the area of perfectly clear terpolymers along the line does not extend 15 quite to the 5 percent line at this point of the graph; However, point 10, which is about 4 percent away from the line in the same direction as point 7, is clear. Below the line, points 11, 12, 13, 14, 15 and 16 are clear, and of these points 12, 13, 15 and 16 are well beyond the 5 20 percent distance from the line. However, with those points it will be noted that the color was yellow and hence polymers not farther than 5 percent away from the line are preferred. Point 17 is in the opaque area.

The viscosity data in Table II show the effect of com25 position on viscosity. Thus, increase in concentration of either styrene or methyl methacrylate decreases the molecular weight. By virtue of the present invention, one can choose a terpolymer composition within a considerable range of molecular weights and yet having clarity. ³θ Example 3

This example presents data on the ternary system styrene/acrylonitrile/methyl vinyl ketone.

By the procedures used in Example 1, the composition 35 of the binary polymerization azeotrope styrene/methyl vinyl ketone was calculated, taking styrene as Mj and methyl vinyl ketone as M₂. The reactivity ratios used were ri=0.29 and r₂=0.35. The binary polymerization azeotrope composition was determined to be 42 weight 40 percent methyl vinyl ketone, 58 weight percent styrene.

The binary polymerization azeotrope composition for styrene/acrylonitrile was taken as 76 weight percent styrene, 24 weight percent acrylonitrile.

Samples containing varying proportions Of the mono45 mers were prepared and polymerized and observations made on the polymers in the manner described in Example 1. However, the polymerization cycle was 29 hours at 90° C., 20 hours at 120° C., and finally 8 hours at 180° C. The data are listed in Table III and plotted ⁵⁰ in Fig. Ill of the drawings.

TABLE III

STYRENE/ACRYLONITRILE/METHYL VINYL KETONE TERPOLYMERS

<td rowspan="2"> Sample No.</td><td rowspan="2"> Composition, weight percent, S/AN/MVK</td><td colspan="2"> Appearance</td><td rowspan="2"> Alcohol solubles content, weight percent</td><td rowspan="2"> Specific viscosity, total polymer</td>

<td> Clarity</td><td> Color</td>

<td> 1_______</td><td> 72/18/10</td><td> C—Clear_____</td><td> Colorless..</td><td> 5.42</td><td> 0.177</td>

<td> 2_______</td><td> 68/13/19</td><td> _____do........</td><td> —.do_______</td><td> 5.81</td><td> 0.158</td>

<td> 3_______</td><td> 63/ 7/30</td><td> _____do________</td><td> ...do.......</td><td> ---------</td><td> ----------</td>

<td> 4_______</td><td> 58/ 0/42</td><td> _____do........</td><td> ...do_______</td><td></td><td> —</td>

<td> δ_______</td><td> 80/15/ 5</td><td> T—v. turbid.</td><td> White.....</td><td></td><td></td>

<td> 6-._____</td><td> 75/ 5/20</td><td> O—Opaque..</td><td rowspan="2"> —do....... Yellow....</td><td></td><td> ___</td>

<td> 7_______</td><td> 65/25/1U</td><td> H—Hazy.....</td><td> —</td><td></td>

<td> 8_______</td><td> 60/20/20</td><td> .....do________</td><td> ...do.......</td><td> ----------</td><td> —</td>

<td> 9_______</td><td> 55/15/30</td><td> T—Turbid...</td><td> —do......_</td><td></td><td></td>

<td> 10......</td><td> 76/24/ 0</td><td> C—Clear.....</td><td> Colorless..</td><td></td><td></td>

S=styrene; AN=acrylonitriIe; MVK=methyl vinyl ketone.

As in the other examples, the terpolymers prepared from monomeric mixtures whose compositions are on the line joining the two binary azeotrope compositions, are clear and colorless. Points 5 and 6, which are more than 5 percent away from the line in the direction of increasing styrene content, are respectively turbid and white,

2,820,128 and opaque and white. Points 7, 8 and 9, which are on the opposite side of the line and more than 5 percent away from the line, were all yellow, points 7 and 8 being hazy and point 9 turbid.

Example 4

This example presents data on the ternary system styrene/acrylonitrile/methacrylonitrile.

Considering styrene as Mi and methacrylonitrile as M₂, the reactivity ratios are zr=O.3O and r₂=0.16. From ¹⁰these data, in the manner set forth in Example 1, the binary polymerization azeotrope composition of styrene/ methacrylonitrile was calculated to be 65 weight percent styrene, 35 weight percent methacrylonitrile. The composition for the styrene/acrylonitrile binary polymerization azeotrope composition was taken at 24 weight percent acrylonitrile, 76 weight percent styrene.

Samples were prepared and tested in the manner set forth in Example 1. For samples Nos. 1 to 10, inclusive, ₂θ the polymerization cycle was 24 hours at 90° C., 24 hours at 120° C., and 8 hours at 180° C. For samples Nos. 11 to 20, inclusive, the polymerization cycle was 24 hours at 90° C., 30 hours at 120° C., and 8 hours at 180° C. This difference was a matter of convenience and did not _2gsignificantly affect the observed polymer properties.

The first eight compositions selected for test fall on the line joining the two binary polymerization azeotrope compositions. Samples 9-12, inclusive, intercept that line at 10 percent methacrylonitrile concentration. Samples ₃₀13-17, inclusive, intercept the line at 5 percent acrylonitrile composition. Samples 18, 19 and 20 intercept the line at about equal weight percentages of acrylonitrile and methacrylonitrile with decreasing percentages of styrene. The data on compositions and polymer properties 35 are set forth in Table IV.

TABLE IV

STYRENE/ACRYLONITRILE/METHACRYLONITRILE 40 TERPOLYMERS

Sample No.

Composition, weight percent, S/AN/MN

Appearance

Clarity

Color

Alcohol solubles content, weight percent

Specific viscosity, total polymer

2..

3..

4..

5..

6..

7..

8..

9..

10.

11.

12.

13.

14.

15.

16.

17.

18.

19.

20.

74/21/ 5 73/17/10 71/14/15 70/10/20 68/ 7/25 66/ 4/30 65/ 0/35 65/25/10 70/20/10 75/15/10 80/10/10 80/ 5/15 75/ 5/20 70/ 5/25 65/ 5/30 60/ 5/35 75/10/15 65/15/20 60/20/20

C—Crystal clear. _____do......... _____do_________ _____do_________

C—Clear______ _____do.________ _____do_________ .....do...._____

H—Hazy.—

C—Clear._____ _____do_________

O—Opaque... _____do_________

T—Turbid.... C—Clear______ _____do_________ _____do.._______

H—Hazy______

C—Clear______

T—Turbid....

Colorless.. 3.24 0.206

...do_______ —do_______ —do_______

SI. yellow. ...do_______

...do_______

...do_______

...do.—... ...do_______

Colorless.. White_____

...do_________ —do_______

Colorless-.

L. yellow.

...do________

White_____

Lt.yellow.

Yellow....

3.42

4.46

4.14

3.99

2.54

3.69 2.06

0.173 0.156

0.140 0.135 0.121 0.114 0.105

8-styrene; AN=acrylonltrile; MN -methacrylonitrile.

The data of Table IV on composition of monomeric ⁶⁵mixtures and appearance of polymers are set forth graphically in Fig. IV of the drawings. It will be noted that all of the polymers made from terpolymer compositions lying within 5 percent of each side of the line joining the two binary polymerization azeotrope compositions were clear with the exception of point 18. This point, lying 4 percent away from the line in the direction of increasing styrene concentration, contained a white haze and therefore is not considered to be within the area of clear terpolymers lying along the line. However, even here it is ⁷⁵ interesting to note that the haziness appears only at a considerable distance from the line; note clear points 11 and 15. Polymers within 3 percent of the line on this side of the line are clear.¹ As in the other examples, opacity appears more quickly as one moves away from the line in the direction of increasing styrene concentration than it appears moving away from the line in the opposite direction. However, point 9 below the line and outside the 5 percent distance was hazy and point 20 similarly located but having a greater quantity of methacrylonitrile and being somewhat farther from the line was turbid.

With respect to color, the observation made earlier that the practice of the present invention permits the production of polymers having minimum color is also borne out in this example. Color in general increases as one moves away from the line. However, with this system it appears that increasing color is somewhat related to increasing methacrylonitrile content and decreasing acrylonitrile content with a given styrene content, and the color also increases in the direction of decreasing styrene content.

Example 5

This example presents data on the ternary system vinylxylene/acrylonitrile/methyl methacrylate.

The reactivity ratios for the system vinylxylene/acrylonitrile, and for the system vinylxylene/methyl methacrylate, were assumed not to differ essentially for the purposes of this invention from the reactivity ratios of the corresponding systems styrene/acrylonitrile and styrene/ methyl methacrylate, respectively. This assumes that the introduction of two methyl groups into the aromatic nucleus of styrene does not greatly alter the polarity and steric properties of the vinyl double bond. Mole ratios for the two binary polymerization azeotropes were calculated in the manner described in the preceding examples, and these were then converted to weight ratios, employing the molecular weight of vinylxylene in each instance instead of the molecular weight of styrene.

In this manner the binary polymerization azetrope composition of vinylxylene/acrylonitrile was calculated to be 80.3 weight percent vinylxylene, 19.7 weight percent acrylonitrile. Similarly, the binary polymerization azeotrope composition of vinylxylene/methyl methacrylate was calculated to be 59.7 weight percent vinylxylene, 40.3 weight percent methyl methacrylate.

Samples were prepared and tested in the manner set forth in Example 1. The vinylxylene employed was a mixture of isomers, and was believed to contain a small amount of close-boiling saturated alkylbenzenes. This impurity, of course, could be expected to affect the polymerization results to some extent.

Samples 1 to 6, inclusive, fall on or approximately on the line joining the two binary polymerization azetrope compositions. Samples 7 and 8 were selected to lie fairly close to the line and on opposite sides of the line. Samples 9 and 10 lie the greatest distance from the line in the direction of increasing vinylxylene content, whereas samples 15-18 are on the opposite side of the line and cover a variety of compositions. Samples 11 and 12 are binary mixtures of vinylxylene with methyl methacrylate, and samples 13 and 14 are binary mixtures of vinylxylene with acrylonitrile. The data on compositions and polymer properties are set forth in Table V, and shown graphically in Fig. V of the drawings.

¹ If the value of the binary styrene/methacrylonitrile azeotrope composition is calculated from ri=0.25 and rz=0 25 which reactivity ratios for this binary system have been reported in the literature, the azeotrope is 61 percent styrene, 39 percent methacrylonitrile. Using this (rather than 65 percent styrene, 35 percent methacrylonitrile used in drawing Fig. IV), hazy point 18 falls just outside the 5 percent line, i. e. is slightly more than 5 percent away from the line joining the two binary azeotropes. It is possible these reactivity ratios are more accurate. However, the ratios n=0.30 and rz=0.16 are considered probably better and have therefore been used in the calculations made for this example.

2,820,128

TABLEV

VINYLXYLENE/ACRYLONITRILE/METHYL METHACRYLATE TERPOLYMERS

TABLE VI

Sample No.

Composition, weight percent, AN/MMA/VX

Appearance

Clarity

Color

STYRENE/AORYLONITRILE/MONOETHYL MALEATE TER POLYMERS

<td> 5 „ , . Sample</td><td> Composition, weight,</td><td colspan="2"> Appearance</td>

<td> No.</td><td> percent, S/AN/MEM</td><td> Clarity</td><td> Color</td>

1.......

2-....3_._....

4_______

5......:

6_______

7.......

8.......

9_______

10--.—

11______

12______

13......

14—__ _

15......

16______ ιβΣΖΣΖΖΞ

0/40/60 3/34/63 . 6/28/66

11/18/71 16/ 7/77 20/ 0/80 10/23/67 12/12/76

5/15/80 7/ 7/87 0/45/55 0/35/65

25/ 0/75 15/ 0/85 30/10/60 25/30/45 55/20/25 . 20/60/20

C—Clear (sparkling)______

-----do___________________

C—Clear (si. haze)________ _____do_____________________

C-—Clear (v. si. haze).— C—Clear.......___________

C—Clear (sparkling)______

H—Hazy__________________

T—Turbid..............

..—do_________________....

C—Clear (sparkling)______

-----do____________________.

C—Clear..—.......... ... T—Turbid________________

H—Hazy__________________

O—Opaque_______________ _____do____________......... .....do.....................

Colorless.

Do. Bluish white.

Do. Colorless. SI. yellow. Colorless. Bluish white. White.

Do. Colorless.

Do.

SI. yellow. White. Bluish white. L. yellow. Yellow.

SI. yellow.

1_______

2_______

3..-—.

4_______

5.._____

6____...

7.......

8_______

9_______

10——

11______

76/24/ 0 73/21/ 6 65/15/20 57/ 9/34 45/ 0/55 68/12/20' 71/23/ 6 62/18/20 58/22/20 50/30/20 20/60/20

C—Clear_________:

_____do___________________ .....do______.....________

C—Clear (v. si. haze)—

C—Clear———.______

O—Opaque_____________

C—Clear_____...........

____.do.__________________

--—do.—_______________

T—Turbid—____________

O—Opaque.________....

75/ 5/20 — do80/10/10 .....do..

Colorless.

Lt. yellow.

Do.

Do.

Colorless.

White.

Lt. yellow.

Do.

Do.

Yellow.

Lt. yellow (soft and sticky).

White. ’ ?

Do.

AN=acrylonitrile; MMA=methyl methacrylate; VX=vinylxylene

It will be noted in examining the drawing and data that all of the ploymers made from monomer mixtures whose compositions lie on the line joining the two binary polymerization azeotropes were clear. Some slight variations in appearance are noted, but none of these samples departs at all from the “clear” category. Similar to the effect noted in the preceding examples, clarity decreases much more rapidly in the direction of increasing vinylxylene concentration than in the opposite direction when moving away from the line. Thus, point 7 was of sparkling clarity, while point 8 on the opposite side of the line and containing a larger quantity of vinylxylene was classified as hazy.. Thus, the limit of area of clear terpolymers approaches the line rather closely (i. e., to within 1 %) in this region. This is also noted from the fact that point 14 was turbid. Note, however, that hazy point 8 within the 5% line is clearer than turbid points 9 and 10 outside the 5% line, illustrating that on either side of the principal line those compositions lying within 5 % of the principal line are preferred.

Example 6

This example presents data on the ternary system styrene/acrylonitrile/monoethyl maleate.

Considering styrene as Mi and monoethyl maleate as M₂, the reactivity ratios are ri=0.13 and r₂=0.035. From these data, in the manner set forth in Example 1, the binary polymerization azeotrope composition of styrene/ monoethyl maleate was calculated to be 44.7 weight percent styrene, 55.3 weight percent monoethyl maleate. The composition for the styrene/acrylonitrile binary polymerization azeotrope composition was similarly calculated

S=styrene; AN=acrylonitrile; MEM=monoethyl maleate.

As in the other examples, it will be observed that the polymers made from monomeric mixtures whose compositions fall on the line joining the two binary polymeriza, tion azeotropes are clear. Further, the area of clarity25 lying along the line is appreciable, and is greater below the line, i, e., in the direction of decreasing styrene content, than above the line in the direction of increasing ? styrene content. Thus, point 6 lying between 3 and 4 : percent away from the line in the direction of increasing 30 styrene content, was opaque, so that the area of clear terpolymers does not extend this far in this part of the graph. In comparison point 8, directly opposite point 6 on the other side of the line, is clear; see also point 7. Continuing along the.20 percent monoethyl maleate line, 35 point 9, which is about 8 percent away from the line, is clear. However, by the time point 10 is reached, the polymer made from the monomeric having that composition is turbid, and still further away from the line . point 11 whose polymer was opaque. On the opposite 40 side of the line, points 12 and 13 are opaque.

These data show that, as in other examples, opacity appears more quickly as one moves away from the line in the direction of increasing styrene concentration that it appears in moving away from the line in the opposite direction.

⁴⁵ The dished lines drawn on each side of the principal line and 5 percent away from that line includes compositions which are preferred. Even in those regions of the composition diagram in' which non-clear polymers are formed, e. g. point 6, such polymers are more transparent, ⁵⁰ i. e. less opaque, than those drawn from compositions in the same region but lying outside the 5 percent line, e. g. point 12.

Example 7 as 76.3 weight percent styrene, 23.7 weight percent aery- 55 lonitrile.

Samples were prepared and tested in the manner set forth in Example 1. For most of the samples the polymerization cycle was 24 hours at 90° C., 25 hours at 120° C., and 7½ hours at 180° C. For samples 5 and 9 the 60 cycle was 24 hours at 90° C., 46½ hours at 120° C. For sample 11, the cycle was 24 hours at 90° C., 25 hours at 120° C.

The first five compositions selected for test fall on the line joining the two binary polymerization azeotrope com- 65 positions. Samples 6, 8, 9, 10, 11 and 12, as well as sample 3, cut across that line on a line of constant 20 weight percent monoethyl maleate, thus covering a wide variety of compositions. Samples 7 and 13 are on opposite sides of the line from each other, are disposed at a considerable distance from the other points, and contain 10 percent and less monoethyl maleate. ^:

The data on compositions and polymer properties are set forth in Table VI, and are given graphically in Fig, VI of the drawings. 75

This example presents data on the ternary system styrene/acrylonitrile/normal butyl methacrylate.

The reactivity ratios for the binary system styrene/nbutyl .methacrylate were assumed not to differ essentially for the purposes of this invention from the reactivity ratios of the corresponding system styrene/methyl methacrylate. This assumes that a moderate increase in the chain length of the alkyl group in the alkyl methacrylates over the single carbon atom in the methyl groups of methyl methacrylate does not greatly alter the polarity and steric properties of the vinyl double bond. Mole ratios for the binary polymerization azeotrope were calculated in the manner described in Example 1, and these were then converted to weight ratios, employing the molecular weight of n-butyl methacrylate instead of the molecular weight of methyl methacrylate.

In this manner the binary polymerization azeotrope composition of styrene/n-butyl methacrylate was calculated to be 47.2 weight percent styrene, 52.8 weight percent n-butyl methacrylate. Similarly, the binary polymerization azeotrope composition of styrene/acrylonitrile

2,829,128 was calculated to be 76.3 weight percent styrene, 23.7 weight percent acrylonitrile.

Samples were prepared and tested in the manner set forth in Example 1. The polymerization cycle was 24 hours at 90’ C., 24 hours at 120’ C., 8 hours at 180° C. 5 A variety of ternary compositions was chosen to cover points on or approximately on the line joining the two binary azeotrope compositions and a considerable number of points on either side of that line. The data on compositions and polymer properties are set forth in Table 10 VII, and shown graphically in Fig. VII of the drawings.

TABLE VII nitrile was calculated to be 76 weight percent styrene, 24 weight percent acrylonitrile.

Samples were prepared and tested, and observations made, as set forth in Example 1. The polymerization cycle was 24 hours at 90° C., 24 hours at 120° C., 8 hours at 180° C. A variety of ternary compositions was chosen to cover points on the line joining the two binary azeotrope compositions and a considerable number of points on either side of that line. The data on compositions and polymer properties are set forth in Table VIII, and shown graphically in Fig. VIII of the drawings.

TABLE VIII

STYRENE/ACRYLONITRILE/n-BETYL METHACRYLATE TERPOLYMERS

STYRENE/ACRYLONITRILE/ISOPROPYL METHACRYLATE TERPOLYMERS

Sample No.

Composition, weight, percent, S/AN/BMA

Appearance

Clarity

Color

Sample No.

S/AN/i-PMA

Appearance

Clarity

Color

76/24/ 0 71/19/10 66/15/19 61/11/28 55/ 6/39 47/ 0/53 70/15/15 65/ 5/30 60/ 5/35 50/ 7/43 45/ 8/47 , 30/45/25

20/40/40 25/20/55 , 80/15/ 5 85/ 5/10

C—Crystal dear________ ——do___________________ _____do___________________

-_--.do____-__________— _____do___________________ _____do_______________

H—Hazy,_________

T—Turbid-------------H—SI. hazy_____________ —do—...............

C—Crystal clear________

O—Opaque.—.___________ —do___________________

C—Clear—._________

O—Opaque______—_____

—...do___________________

Colorless. Do. Do. Do.

Do.

Do.

White.

Do. Do. Do. Colorless. Yellow.

Do.

Lt. yellow. White.

Do.

“Styrene; AN=acrylonltrl)e; n-BMA“normal butyl methacrylate

These data again show that terpolymers prepared from monomeric; mixtures whose compositions are taken from _ggalong the line joining the two binary polymerization azeotropes are clear and that the area of clarity is not restricted to the line but covers a significant area along the line. Points 11 and 14 further demonstrate that the area of clarity in this portion of the graph extends a very considerable distance away from the line. However, points 7, 9, and 10 lying in the neighborhood of 3 percent away from the line point out regions wherein the area of perfect clarity does not extend very far from the line. Even in these regions, however, polymers within 5 percent of the line on either side are preferred as they are clearer -15 and less opaque than similar polymers farther away from the line. Thus, for example, compare points 9 and 8 and points 7 and 15. .

Example 8 .θ

This example presents data on the ternary system styrene/acrylomtrile/isopropyl methacrylate.

The reactivity ratios for the binary system styrene/isopropyl methacrylate were assumed not to differ essentially for the purposes of this invention from the reac- 55 tivity ratios for the corresponding systems styrene/ methyl methacrylate (Example 2) and styrene/n-butyl methacrylate (Example 7). The results obtained proved this assumption to be correct, and that a change in chain length of the alkyl group from one. pr four to three 60 carbon atoms, or a branching of the chain in the alkyl group as compared with the straight chain alkyl group in n-butyl methacrylate, does not greatly alter the polarity and steric properties of the vinyl double bond. Mole ratios for the binary polymerization azeotrope were cal- (&gt;5 culated in the manner described in Example 1, using the reactivity ratios employed in Example 2, and the resulting mple ratios were then converted to weight ratios, employing the molecular weight of isopropyl methacrylate instead of the molecular weight of methyl methacrylate. 70

In this manner the binary polymerization azeotrope composition of styrene/isopropyl methacrylate was calculated to be 47.7 weight percent styrene, 52.3 weight percent isopropyl methacrylate. Similarly, the binary polymerization azeotrope composition of styretie/acrylo- 75

76/24/ 0

72/20/ 8 66/15/19 60/10/30

54/ 5/41

48/ 0/52 74/16/10 66/ 9/25

62/18/20 55/35/10 40/25/35 80/10/10

C—Clear____________ _____do_______________ _____do_______________ _____do________________ ______do.______________

C—Sparkling clear..

H—Hazy—______ .—do.______________

O—Clear____________

T—Turbid—________

C—Clear____________

T—Turbid..---.....

Yellow.

Lt. yellow.

Do.

Do.

Colorless.

Do.

Lt. yellow. .

White to Lt. yellow.

Yellow.

Do.

Do.

White (very It. yellow).

S=styrene; AN^aerylonitrile; ί-ΡΜΑ-isopropyl methacrylate.

These data again show that clear terpolymers prepared from monomeric mixtures whose compositions are taken from along the line joining the two binary polymerization azeotropes are clear, and that the area of clarity is not restricted to the line but covers a significant area along the line. As noted in previous examples, the clarity decreases more rapidly as compositions are chosen moving away from the line in the direction of increasing styrene content, than in compositions moving away from the line on the opposite side of the line. Compare, for example, points 7 and 8, each about 4 percent away from the line on the side of increasing styrene content and each of which is hazy, with point 9 about 4 percent away from the line on the opposite side of the line and which is clear. In the case of points 7 and 8 and adjacent compositions, polymers within 5 percent of the line are preferred as they are clearer and less opaque than similar polymers farther away from the line; compare, for example, points 7 and 12, the former being only hazy and the latter turbid. It is also noted that point 11 demonstrates that the area of clear terpolymers extends for a much greater distance away from the line in that region than on the opposite side of the line. It is interesting to note even here, however, that though point 4 was light yellow and points 5 and 6 were colorless, point 11 is yellow and thus not as preferred as the points nearer the line or on the line.

As in the other examples, the dashed lines drawn on each side of the principal line and 5 percent away from that line includes compositions which are preferred.

While the invention has been described herein with particular reference to various preferred embodiments thereof, and examples have been given of suitable proportions and conditions, it will be appreciated that variations from the details given herein can be effected without departing from the invention. When desired, the terpolymers of the present invention can be blended with other polymers, plasticizers, solvents, fillers, pigments, dyes, stabilizers, and the like, in accordance with the particular use intended.